AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE PUEBLO CO 737 AM MST THU NOV 20 2008 .UPDATE... WEB CAMS SHOWING DENSE FOG AND PROBABLY SOME LIGHT FREEZING DRIZZLE AT CRIPPLE CREEK...CANON CITY AND RYE. THE SAME COULD LIKELY BE SAID ACROSS PORTIONS OF THE SANGRE DE CRISTO MOUNTAINS...WET MOUNTAIN VALLEY...SOUTHERN FOOTHILLS/RATON PASS...AND TELLER COUNTY. EXPANDED THE WINTER WEATHER ADVISORY FOR THESE AREAS DURING PARTS OF TODAY. THE STRATUS/FOG/DRIZZLE WILL LIKELY BURN OFF ACROSS THE SANGRE DE CRISTO MOUNTAINS...WET MOUNTAIN VALLEY...AND WESTERN FREMONT COUNTY LATER THIS MORNING OR EARLY AFTERNOON. METZE && .PREV DISCUSSION... /ISSUED 641 AM MST THU NOV 20 2008/ UPDATE... A QUICK UPDATE ON THE FOG AND FREEZING DRIZZLE POTENTIAL. 11U-3.9(FOG) SATELLITE IMAGERY DATA SHOWED STRATUS NOW COVERS A GOOD "CHUNK" OF SOUTHEAST CO TO THE SANGRE DE CRISTO MOUNTAINS AND THROUGH CHAFFEE COUNTY. WEB CAMS AROUND SUNRISE SHOWED FOG...DENSE AT TIMES...AT RYE...CANON CITY...CRIPPLE CREEK...WIDEFIELD...AND MONUMENT TOWARDS THE COUNTY LINE. ALSO...NOTED RADAR VERY LIGHT ECHO RETURNS PICKING UP SOME OF THE FOG/DRIZZLE AROUND FORT CARSON TO CANON CITY TO RYE AND TRYING TO EXPAND TOWARDS COLORADO SPRINGS. CLOUD CEILING HAVING A TOUGH TIME REACHING THE GROUND IN COLORADO SPRINGS THANKS TO SLIGHTLY LOWER DEW POINTS AND A NORTHEAST WIND AT 10-15 MPH CREATING DOWNSLOPE DRYING OFF THE PALMER DIVIDE. THERE ARE SOME RELATIVELY HIGHER DEW POINTS...MIDDLE TO UPPER 20S...AROUND DENVER INTO NORTHEASTERN CO. THIS COULD STILL MOVE INTO EL PASO COUNTY JUST AS THE SURFACE WIND VEERS TO THE SOUTHEAST-SOUTH BY LATER THIS MORNING AND THROUGH THE AFTERNOON. THIS FACT MAKES ME A LITTLE HESITANT IN DROPPING THE WINTER WEATHER ADVISORY FOR AREAS OF DENSE FOG AND FREEZING DRIZZLE ACROSS EL PASO COUNTY. THE 13KM RUC MODEL STILL WANTS TO VEER THE SURFACE WINDS TO THE EAST- SOUTHEAST NOW BETWEEN 15Z-18Z/20 AND SOUTHERLY AROUND 12Z/20. VERY TOUGH CALL AND TERRAIN DICTATES EVERYTHING AROUND COLORADO SPRINGS. METZE PREV DISCUSSION... /ISSUED 347 AM MST THU NOV 20 2008/ SHORT TERM... (TODAY AND TONIGHT) .AREAS OF FREEZING DRIZZLE/DENSE FOG ACROSS EL PASO COUNTY TODAY... .MUCH COLDER ACROSS SOUTHEASTERN CO TODAY... CURRENTLY...HAND SURFACE ANALYSIS AT 07Z/20 SHOWED THE FRONTAL BOUNDARY WELL PAST SOUTHEASTERN CO AND UP AGAINST THE EASTERN CO MOUNTAINS. THE WELL ADVERTISED 1040-1045MB SURFACE HIGH WAS ABOUT TO ENTER MT/ND EARLY THIS MORNING. STRATUS HAS EXPANDED ACROSS MUCH OF THE EASTERN 1/2 OF CO. SATELLITE 11U-3.9U(FOG) IMAGERY REVEALED THE LOW CLOUDS MAKING IT INTO FREMONT COUNTY...EASTERN SLOPES OF THE SANGRE DE CRISTO MOUNTAINS...LOWER ELEVATIONS OF TELLER COUNTY WITH PIKES PEAK STILL CLEAR PER LIVE WEB CAM...AND OF COURSE ALL OF SOUTHEASTERN CO. AS OF 09Z/20...THE FOG LEVEL WAS AROUND THE 6.5K-9K FT MSL LAYER. CEILINGS ARE STILL MVFR-LOW VFR FOR ELEVATIONS BELOW 6K FT MSL ACROSS THE SOUTHEASTERN CO PLAINS. LIVE WEB CAMS ACROSS MONUMENT SHOW DENSE FOG. A CALL TO THE EL PASO COUNTY SHERIFF INDICATED ONLY DENSE FOG IN MONUMENT AND NO FREEZING DRIZZLE YET. RYE DOESN`T LOOK TOO FOGGY YET PER LIVE WEB CAM. THE KMNH AWOS SENSOR JUST NORTH OF EL PASO COUNTY HAS 1/4SM FZFG AND 25F. TEMPERATURES ACROSS NORTHERN EL PASO COUNTY ARE IN THE MIDDLE/UPPER 20S WITH LOWER/MIDDLE 30S ACROSS SOUTHERN EL PASO COUNTY. THE NORTHEAST WIND(DOWNSLOPE OFF THE SOUTHERN PALMER DIVIDE) AT COS IS KEEPING THE CEILING STILL LOW VFR...BUT THAT COULD CHANGE CONSIDERING BULLSEYE AWOS IS 300 FOOT AND 3 MILES MIST AT 09Z/20. TODAY...WELL ADVERTISED 20-35 DEGREE COLDER TEMPERATURES ACROSS SOUTHEAST CO STILL LOOK ON TRACK. DIURNAL TEMPERATURE RANGES ACROSS OUR SOUTHEASTERN CO MOUNTAINS AND ADJACENT PLAINS MAY ONLY BE 5-10 DEGREES FROM EARLY MORNING TEMPERATURES. GREATEST IMPACT WEATHER WILL BE THE FOG AND POSSIBLE DRIZZLE/FREEZING DRIZZLE ACROSS PORTIONS OF THE I-25 CORRIDOR AND WESTWARD TOWARDS THE MOUNTAINS. IT APPEARS THE HIGHEST PROBABILITY FOR AREAS OF DENSE FOG/FREEZING DRIZZLE WILL BE ACROSS EL PASO COUNTY THROUGH TODAY AND PROBABLY AROUND THE RATON AND LA VETA PASSES. LCL HEIGHTS ARE ALREADY NEAR THE SURFACE. FOG/STRATUS WILL CONTINUE TO FILL IN ACROSS MUCH OF SOUTHEASTERN CO. SURFACE WINDS SHOULD VEER FROM THE NORTHEAST(DOWNSLOPE OFF THE SOUTHERN PALMER DIVIDE) TO THE SOUTHEAST-SOUTH ACROSS EL PASO COUNTY TODAY. THE 08Z/20 13KM RUC MODEL HAS THE EAST-SOUTHEAST WINDS ACROSS EL PASO COUNTY BETWEEN 13Z-16Z/20 THIS MORNING. THE COMBINATION OF WEAK UPSLOPE FLOW...TRAPPED COLD LOW-LEVEL MOISTURE...AN INVERSION ALOFT...AND RELATIVELY DRIER ALOFT ALOFT...SHOULD KEEP THE LIFR-IFR CIGS/VIS ACROSS MUCH OF EL PASO COUNTY AND A NARROW RIBBON BETWEEN 6K-9K FT MSL ALONG THE EASTERN SLOPES OF THE WET MOUNTAINS...WET MOUNTAIN VALLEY...AND SOUTHERN SANGRE DE CRISTO MOUNTAINS. CONSIDERING ITS THE FIRST EVENT OF THE SEASON AND MORNING/AFTERNOON RUSH HOURS...WILL GO WITH A WINTER WEATHER ADVISORY FOR AREAS OF DENSE FOG AND FREEZING DRIZZLE ACROSS EL PASO COUNTY. STILL THINK THERE COULD BE SOME VERY LIGHT SNOW OR FLURRIES CONSIDERING THE -3C TO -10C LAYER 2D FRONTOGENETICAL FORCING COMES INTO THE I-25 CORRIDOR WITH A SECOND SURGE OF COLD MOIST LOW LEVEL AIR. MEANWHILE...AROUND THE CONTINENTAL DIVIDE AND THE SAN LUIS VALLEY...IT SHOULD BE MOSTLY SUNNY AND RELATIVELY WARMER. THIS COULD BE ONE OF THOSE EVENTS WHERE LEADVILLE IS SLIGHTLY WARMER THAN COLORADO SPRINGS. TONIGHT...LOW LEVEL CP AIR MASS BEGINS TO RECEDE EASTERN CO WITH WEST-NORTHWESTERLY FLOW ALOFT. MID-LEVEL WARM AIR ADVECTION KICKS-IN TONIGHT WITH 700MB TEMPERATURES INCREASING TO +2C TO +3C ACROSS THE I-25 CORRIDOR. LOW LEVEL FLOW BECOMES MORE SOUTHERLY AND SHOULD HELP TO START DIMINISHING THE LOW CLOUDS ACROSS SOUTHEASTERN CO...EXCEPT THE SOUTHERN PALMER DIVIDE/COS WHERE IT`S STILL UPSLOPE FLOW. AS TYPICAL WITH THESE SCENARIOS....THE STRATUS/FOG MAY HANG ON ACROSS EL PASO COUNTY UNTIL THE SOUTHWEST-WESTERLY FLOW CAN DEVELOP LATE TONIGHT OR FRIDAY MORNING. MAY NEED TO EXTEND THE WINTER WEATHER ADVISORY IN TIME ACROSS EL PASO COUNTY THROUGH NIGHT...BUT WILL LET THE DAY SHIFT HANDLE THIS IF NEEDED. 17 LONG TERM... (FRIDAY THROUGH WEDNESDAY) .DRY WEATHER PATTERN TO CONTINUE ACROSS SOUTHEAST COLORADO... QUIET AND STABLE WEATHER PATTERN IS EXPECTED TO CONTINUE THROUGH AT LEAST EARLY NEXT WEEK AS THE ROCKIES REMAIN ON THE EAST SIDE OF A LONGWAVE RIDGE WITH AXIS OVR THE INTERMTN REGION AND WESTERN CANADA. TEMPERATURES WILL CONTINUE TO RUN ABOUT 5-10 DEGREES ABOVE AVERAGE...WITH NO MEASURABLE PRECIP EXPECTED FOR THE NEXT SIX DAYS. RESIDUAL CLOUDS SHOULD CLEAR BY FRI MORNING...AS A LEE TROUGH RE-ESTABLISHES...AND SRLY FLOW STRENGTHENS IN ADVANCE OF ANOTHER SHORTWAVE MOVING THROUGH SD AND ERN NE. NO REAL WX CHANGE IS EXPECTED WITH THIS SYSTEM...AS THE COLDER AIR AND ANY REAL MOISTURE REMAIN WELL TO THE NE OF OUR CWA. A SHORTWAVE RIDGE WILL FOLLOW ON SATURDAY...THEN ANOTHER WEAK TROUGH WILL FOLLOW A SIMILAR TRACK THRU THE DAKOTAS ON SUN. ONCE AGAIN...THIS SYSTEM WILL NOT BRING MUCH MOISTURE TO THE AREA...MAYBE JUST AN INCREASE OF CLOUDS TO THE NRN ZONES. THE UPPER RIDGE WILL BUILD MON THRU WED...AND DRY CONDITIONS WILL LIKELY CONTINUE WITH GENERALLY SUNNY SKIES AND TEMPS OVR THE PLAINS STAYING IN THE 60S. THE PATTERN FINALLY BREAKS DOWN IN TIME FOR THANKSGIVING...AS A VERY COMPLEX SCENARIO SETS UP INVOLVING TWO BRANCHES OF THE POLAR JET. FAR TO EARLY TO SAY HOW THIS PATTERN CHANGE WILL AFFECT THE AREA...BUT THERE IS AT LEAST THE CHANCE FOR SOME MUCH NEEDED MTN SNOWS BY THE LATTER PART OF NEXT WEEK. 44 AVIATION... ER SHORT TERM DISCUSSION...LIFR-IFR CEILINGS AND VISIBILITIES IN FREEZING FOG/DRIZZLE DRIZZLE SHOULD AFFECT THE KCOS TERMINAL MUCH OF THE DAY AND THROUGH THE NIGHT WHERE TEMPERATURES WILL REMAIN IN THE UPPER 20S TO LOWER 30S. IFR-MVFR CEILINGS WILL CONTINUE AT THE KPUB TERMINAL WITH AREAS OF FOG FOR TODAY...AND THEN CEILINGS AND VISIBILITIES SHOULD IMPROVE TONIGHT. VFR CLEAR BELOW 12K FT MSL CONDITIONS WILL PREVAIL AT THE KALS TERMINAL THROUGH TONIGHT. MOUNTAINS WILL BE OBSCURED IN CLOUDS AND FOG JUST WEST OF THE I-25 CORRIDOR. METZE && .PUB WATCHES/WARNINGS/ADVISORIES... WINTER WEATHER ADVISORY UNTIL 5 PM MST THIS AFTERNOON FOR COZ079- 081-083>085-087-088. WINTER WEATHER ADVISORY UNTIL NOON MST TODAY FOR COZ072-074- 076>078. && $$ 17/17 co AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE PUEBLO CO 641 AM MST THU NOV 20 2008 .UPDATE... A QUICK UPDATE ON THE FOG AND FREEZING DRIZZLE POTENTIAL. 11U-3.9(FOG) SATELLITE IMAGERY DATA SHOWED STRATUS NOW COVERS A GOOD "CHUNK" OF SOUTHEAST CO TO THE SANGRE DE CRISTO MOUNTAINS AND THROUGH CHAFFEE COUNTY. WEB CAMS AROUND SUNRISE SHOWED FOG...DENSE AT TIMES...AT RYE...CANON CITY...CRIPPLE CREEK...WIDEFIELD...AND MONUMENT TOWARDS THE COUNTY LINE. ALSO...NOTED RADAR VERY LIGHT ECHO RETURNS PICKING UP SOME OF THE FOG/DRIZZLE AROUND FORT CARSON TO CANON CITY TO RYE AND TRYING TO EXPAND TOWARDS COLORADO SPRINGS. CLOUD CEILING HAVING A TOUGH TIME REACHING THE GROUND IN COLORADO SPRINGS THANKS TO SLIGHTLY LOWER DEW POINTS AND A NORTHEAST WIND AT 10-15 MPH CREATING DOWNSLOPE DRYING OFF THE PALMER DIVIDE. THERE ARE SOME RELATIVELY HIGHER DEW POINTS...MIDDLE TO UPPER 20S...AROUND DENVER INTO NORTHEASTERN CO. THIS COULD STILL MOVE INTO EL PASO COUNTY JUST AS THE SURFACE WIND VEERS TO THE SOUTHEAST-SOUTH BY LATER THIS MORNING AND THROUGH THE AFTERNOON. THIS FACT MAKES ME A LITTLE HESITANT IN DROPPING THE WINTER WEATHER ADVISORY FOR AREAS OF DENSE FOG AND FREEZING DRIZZLE ACROSS EL PASO COUNTY. THE 13KM RUC MODEL STILL WANTS TO VEER THE SURFACE WINDS TO THE EAST- SOUTHEAST NOW BETWEEN 15Z-18Z/20 AND SOUTHERLY AROUND 12Z/20. VERY TOUGH CALL AND TERRAIN DICTATES EVERYTHING AROUND COLORADO SPRINGS. METZE && .PREV DISCUSSION... /ISSUED 347 AM MST THU NOV 20 2008/ SHORT TERM... (TODAY AND TONIGHT) ..AREAS OF FREEZING DRIZZLE/DENSE FOG ACROSS EL PASO COUNTY TODAY... ..MUCH COLDER ACROSS SOUTHEASTERN CO TODAY... CURRENTLY...HAND SURFACE ANALYSIS AT 07Z/20 SHOWED THE FRONTAL BOUNDARY WELL PAST SOUTHEASTERN CO AND UP AGAINST THE EASTERN CO MOUNTAINS. THE WELL ADVERTISED 1040-1045MB SURFACE HIGH WAS ABOUT TO ENTER MT/ND EARLY THIS MORNING. STRATUS HAS EXPANDED ACROSS MUCH OF THE EASTERN 1/2 OF CO. SATELLITE 11U-3.9U(FOG) IMAGERY REVEALED THE LOW CLOUDS MAKING IT INTO FREMONT COUNTY...EASTERN SLOPES OF THE SANGRE DE CRISTO MOUNTAINS...LOWER ELEVATIONS OF TELLER COUNTY WITH PIKES PEAK STILL CLEAR PER LIVE WEB CAM...AND OF COURSE ALL OF SOUTHEASTERN CO. AS OF 09Z/20...THE FOG LEVEL WAS AROUND THE 6.5K-9K FT MSL LAYER. CEILINGS ARE STILL MVFR-LOW VFR FOR ELEVATIONS BELOW 6K FT MSL ACROSS THE SOUTHEASTERN CO PLAINS. LIVE WEB CAMS ACROSS MONUMENT SHOW DENSE FOG. A CALL TO THE EL PASO COUNTY SHERIFF INDICATED ONLY DENSE FOG IN MONUMENT AND NO FREEZING DRIZZLE YET. RYE DOESN`T LOOK TOO FOGGY YET PER LIVE WEB CAM. THE KMNH AWOS SENSOR JUST NORTH OF EL PASO COUNTY HAS 1/4SM FZFG AND 25F. TEMPERATURES ACROSS NORTHERN EL PASO COUNTY ARE IN THE MIDDLE/UPPER 20S WITH LOWER/MIDDLE 30S ACROSS SOUTHERN EL PASO COUNTY. THE NORTHEAST WIND(DOWNSLOPE OFF THE SOUTHERN PALMER DIVIDE) AT COS IS KEEPING THE CEILING STILL LOW VFR...BUT THAT COULD CHANGE CONSIDERING BULLSEYE AWOS IS 300 FOOT AND 3 MILES MIST AT 09Z/20. TODAY...WELL ADVERTISED 20-35 DEGREE COLDER TEMPERATURES ACROSS SOUTHEAST CO STILL LOOK ON TRACK. DIURNAL TEMPERATURE RANGES ACROSS OUR SOUTHEASTERN CO MOUNTAINS AND ADJACENT PLAINS MAY ONLY BE 5-10 DEGREES FROM EARLY MORNING TEMPERATURES. GREATEST IMPACT WEATHER WILL BE THE FOG AND POSSIBLE DRIZZLE/FREEZING DRIZZLE ACROSS PORTIONS OF THE I-25 CORRIDOR AND WESTWARD TOWARDS THE MOUNTAINS. IT APPEARS THE HIGHEST PROBABILITY FOR AREAS OF DENSE FOG/FREEZING DRIZZLE WILL BE ACROSS EL PASO COUNTY THROUGH TODAY AND PROBABLY AROUND THE RATON AND LA VETA PASSES. LCL HEIGHTS ARE ALREADY NEAR THE SURFACE. FOG/STRATUS WILL CONTINUE TO FILL IN ACROSS MUCH OF SOUTHEASTERN CO. SURFACE WINDS SHOULD VEER FROM THE NORTHEAST(DOWNSLOPE OFF THE SOUTHERN PALMER DIVIDE) TO THE SOUTHEAST-SOUTH ACROSS EL PASO COUNTY TODAY. THE 08Z/20 13KM RUC MODEL HAS THE EAST-SOUTHEAST WINDS ACROSS EL PASO COUNTY BETWEEN 13Z-16Z/20 THIS MORNING. THE COMBINATION OF WEAK UPSLOPE FLOW...TRAPPED COLD LOW-LEVEL MOISTURE...AN INVERSION ALOFT...AND RELATIVELY DRIER ALOFT ALOFT...SHOULD KEEP THE LIFR-IFR CIGS/VIS ACROSS MUCH OF EL PASO COUNTY AND A NARROW RIBBON BETWEEN 6K-9K FT MSL ALONG THE EASTERN SLOPES OF THE WET MOUNTAINS...WET MOUNTAIN VALLEY...AND SOUTHERN SANGRE DE CRISTO MOUNTAINS. CONSIDERING ITS THE FIRST EVENT OF THE SEASON AND MORNING/AFTERNOON RUSH HOURS...WILL GO WITH A WINTER WEATHER ADVISORY FOR AREAS OF DENSE FOG AND FREEZING DRIZZLE ACROSS EL PASO COUNTY. STILL THINK THERE COULD BE SOME VERY LIGHT SNOW OR FLURRIES CONSIDERING THE -3C TO -10C LAYER 2D FRONTOGENETICAL FORCING COMES INTO THE I-25 CORRIDOR WITH A SECOND SURGE OF COLD MOIST LOW LEVEL AIR. MEANWHILE...AROUND THE CONTINENTAL DIVIDE AND THE SAN LUIS VALLEY...IT SHOULD BE MOSTLY SUNNY AND RELATIVELY WARMER. THIS COULD BE ONE OF THOSE EVENTS WHERE LEADVILLE IS SLIGHTLY WARMER THAN COLORADO SPRINGS. TONIGHT...LOW LEVEL CP AIR MASS BEGINS TO RECEDE EASTERN CO WITH WEST-NORTHWESTERLY FLOW ALOFT. MID-LEVEL WARM AIR ADVECTION KICKS-IN TONIGHT WITH 700MB TEMPERATURES INCREASING TO +2C TO +3C ACROSS THE I-25 CORRIDOR. LOW LEVEL FLOW BECOMES MORE SOUTHERLY AND SHOULD HELP TO START DIMINISHING THE LOW CLOUDS ACROSS SOUTHEASTERN CO...EXCEPT THE SOUTHERN PALMER DIVIDE/COS WHERE IT`S STILL UPSLOPE FLOW. AS TYPICAL WITH THESE SCENARIOS....THE STRATUS/FOG MAY HANG ON ACROSS EL PASO COUNTY UNTIL THE SOUTHWEST-WESTERLY FLOW CAN DEVELOP LATE TONIGHT OR FRIDAY MORNING. MAY NEED TO EXTEND THE WINTER WEATHER ADVISORY IN TIME ACROSS EL PASO COUNTY THROUGH NIGHT...BUT WILL LET THE DAY SHIFT HANDLE THIS IF NEEDED. 17 LONG TERM... (FRIDAY THROUGH WEDNESDAY) ..DRY WEATHER PATTERN TO CONTINUE ACROSS SOUTHEAST COLORADO... QUIET AND STABLE WEATHER PATTERN IS EXPECTED TO CONTINUE THROUGH AT LEAST EARLY NEXT WEEK AS THE ROCKIES REMAIN ON THE EAST SIDE OF A LONGWAVE RIDGE WITH AXIS OVR THE INTERMTN REGION AND WESTERN CANADA. TEMPERATURES WILL CONTINUE TO RUN ABOUT 5-10 DEGREES ABOVE AVERAGE...WITH NO MEASURABLE PRECIP EXPECTED FOR THE NEXT SIX DAYS. RESIDUAL CLOUDS SHOULD CLEAR BY FRI MORNING...AS A LEE TROUGH RE-ESTABLISHES...AND SRLY FLOW STRENGTHENS IN ADVANCE OF ANOTHER SHORTWAVE MOVING THROUGH SD AND ERN NE. NO REAL WX CHANGE IS EXPECTED WITH THIS SYSTEM...AS THE COLDER AIR AND ANY REAL MOISTURE REMAIN WELL TO THE NE OF OUR CWA. A SHORTWAVE RIDGE WILL FOLLOW ON SATURDAY...THEN ANOTHER WEAK TROUGH WILL FOLLOW A SIMILAR TRACK THRU THE DAKOTAS ON SUN. ONCE AGAIN...THIS SYSTEM WILL NOT BRING MUCH MOISTURE TO THE AREA...MAYBE JUST AN INCREASE OF CLOUDS TO THE NRN ZONES. THE UPPER RIDGE WILL BUILD MON THRU WED...AND DRY CONDITIONS WILL LIKELY CONTINUE WITH GENERALLY SUNNY SKIES AND TEMPS OVR THE PLAINS STAYING IN THE 60S. THE PATTERN FINALLY BREAKS DOWN IN TIME FOR THANKSGIVING...AS A VERY COMPLEX SCENARIO SETS UP INVOLVING TWO BRANCHES OF THE POLAR JET. FAR TO EARLY TO SAY HOW THIS PATTERN CHANGE WILL AFFECT THE AREA...BUT THERE IS AT LEAST THE CHANCE FOR SOME MUCH NEEDED MTN SNOWS BY THE LATTER PART OF NEXT WEEK. 44 AVIATION... ER SHORT TERM DISCUSSION...LIFR-IFR CEILINGS AND VISIBILITIES IN FREEZING FOG/DRIZZLE DRIZZLE SHOULD AFFECT THE KCOS TERMINAL MUCH OF THE DAY AND THROUGH THE NIGHT WHERE TEMPERATURES WILL REMAIN IN THE UPPER 20S TO LOWER 30S. IFR-MVFR CEILINGS WILL CONTINUE AT THE KPUB TERMINAL WITH AREAS OF FOG FOR TODAY...AND THEN CEILINGS AND VISIBILITIES SHOULD IMPROVE TONIGHT. VFR CLEAR BELOW 12K FT MSL CONDITIONS WILL PREVAIL AT THE KALS TERMINAL THROUGH TONIGHT. MOUNTAINS WILL BE OBSCURED IN CLOUDS AND FOG JUST WEST OF THE I-25 CORRIDOR. 17 && .PUB WATCHES/WARNINGS/ADVISORIES... WINTER WEATHER ADVISORY UNTIL 5 PM MST THIS AFTERNOON FOR COZ084- 085. && $$ 17/17 co AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE PUEBLO CO 347 AM MST THU NOV 20 2008 .SHORT TERM... (TODAY AND TONIGHT) ...AREAS OF FREEZING DRIZZLE/DENSE FOG ACROSS EL PASO COUNTY TODAY... ...MUCH COLDER ACROSS SOUTHEASTERN CO TODAY... CURRENTLY...HAND SURFACE ANALYSIS AT 07Z/20 SHOWED THE FRONTAL BOUNDARY WELL PAST SOUTHEASTERN CO AND UP AGAINST THE EASTERN CO MOUNTAINS. THE WELL ADVERTISED 1040-1045MB SURFACE HIGH WAS ABOUT TO ENTER MT/ND EARLY THIS MORNING. STRATUS HAS EXPANDED ACROSS MUCH OF THE EASTERN 1/2 OF CO. SATELLITE 11U-3.9U(FOG) IMAGERY REVEALED THE LOW CLOUDS MAKING IT INTO FREMONT COUNTY...EASTERN SLOPES OF THE SANGRE DE CRISTO MOUNTAINS...LOWER ELEVATIONS OF TELLER COUNTY WITH PIKES PEAK STILL CLEAR PER LIVE WEB CAM...AND OF COURSE ALL OF SOUTHEASTERN CO. AS OF 09Z/20...THE FOG LEVEL WAS AROUND THE 6.5K-9K FT MSL LAYER. CEILINGS ARE STILL MVFR-LOW VFR FOR ELEVATIONS BELOW 6K FT MSL ACROSS THE SOUTHEASTERN CO PLAINS. LIVE WEB CAMS ACROSS MONUMENT SHOW DENSE FOG. A CALL TO THE EL PASO COUNTY SHERIFF INDICATED ONLY DENSE FOG IN MONUMENT AND NO FREEZING DRIZZLE YET. RYE DOESN`T LOOK TOO FOGGY YET PER LIVE WEB CAM. THE KMNH AWOS SENSOR JUST NORTH OF EL PASO COUNTY HAS 1/4SM FZFG AND 25F. TEMPERATURES ACROSS NORTHERN EL PASO COUNTY ARE IN THE MIDDLE/UPPER 20S WITH LOWER/MIDDLE 30S ACROSS SOUTHERN EL PASO COUNTY. THE NORTHEAST WIND(DOWNSLOPE OFF THE SOUTHERN PALMER DIVIDE) AT COS IS KEEPING THE CEILING STILL LOW VFR...BUT THAT COULD CHANGE CONSIDERING BULLSEYE AWOS IS 300 FOOT AND 3 MILES MIST AT 09Z/20. TODAY...WELL ADVERTISED 20-35 DEGREE COLDER TEMPERATURES ACROSS SOUTHEAST CO STILL LOOK ON TRACK. DIURNAL TEMPERATURE RANGES ACROSS OUR SOUTHEASTERN CO MOUNTAINS AND ADJACENT PLAINS MAY ONLY BE 5-10 DEGREES FROM EARLY MORNING TEMPERATURES. GREATEST IMPACT WEATHER WILL BE THE FOG AND POSSIBLE DRIZZLE/FREEZING DRIZZLE ACROSS PORTIONS OF THE I-25 CORRIDOR AND WESTWARD TOWARDS THE MOUNTAINS. IT APPEARS THE HIGHEST PROBABILITY FOR AREAS OF DENSE FOG/FREEZING DRIZZLE WILL BE ACROSS EL PASO COUNTY THROUGH TODAY AND PROBABLY AROUND THE RATON AND LA VETA PASSES. LCL HEIGHTS ARE ALREADY NEAR THE SURFACE. FOG/STRATUS WILL CONTINUE TO FILL IN ACROSS MUCH OF SOUTHEASTERN CO. SURFACE WINDS SHOULD VEER FROM THE NORTHEAST(DOWNSLOPE OFF THE SOUTHERN PALMER DIVIDE) TO THE SOUTHEAST-SOUTH ACROSS EL PASO COUNTY TODAY. THE 08Z/20 13KM RUC MODEL HAS THE EAST-SOUTHEAST WINDS ACROSS EL PASO COUNTY BETWEEN 13Z-16Z/20 THIS MORNING. THE COMBINATION OF WEAK UPSLOPE FLOW...TRAPPED COLD LOW-LEVEL MOISTURE...AN INVERSION ALOFT...AND RELATIVELY DRIER ALOFT ALOFT...SHOULD KEEP THE LIFR-IFR CIGS/VIS ACROSS MUCH OF EL PASO COUNTY AND A NARROW RIBBON BETWEEN 6K-9K FT MSL ALONG THE EASTERN SLOPES OF THE WET MOUNTAINS...WET MOUNTAIN VALLEY...AND SOUTHERN SANGRE DE CRISTO MOUNTAINS. CONSIDERING ITS THE FIRST EVENT OF THE SEASON AND MORNING/AFTERNOON RUSH HOURS...WILL GO WITH A WINTER WEATHER ADVISORY FOR AREAS OF DENSE FOG AND FREEZING DRIZZLE ACROSS EL PASO COUNTY. STILL THINK THERE COULD BE SOME VERY LIGHT SNOW OR FLURRIES CONSIDERING THE -3C TO -10C LAYER 2D FRONTOGENETICAL FORCING COMES INTO THE I-25 CORRIDOR WITH A SECOND SURGE OF COLD MOIST LOW LEVEL AIR. MEANWHILE...AROUND THE CONTINENTAL DIVIDE AND THE SAN LUIS VALLEY...IT SHOULD BE MOSTLY SUNNY AND RELATIVELY WARMER. THIS COULD BE ONE OF THOSE EVENTS WHERE LEADVILLE IS SLIGHTLY WARMER THAN COLORADO SPRINGS. TONIGHT...LOW LEVEL CP AIR MASS BEGINS TO RECEDE EASTERN CO WITH WEST-NORTHWESTERLY FLOW ALOFT. MID-LEVEL WARM AIR ADVECTION KICKS-IN TONIGHT WITH 700MB TEMPERATURES INCREASING TO +2C TO +3C ACROSS THE I-25 CORRIDOR. LOW LEVEL FLOW BECOMES MORE SOUTHERLY AND SHOULD HELP TO START DIMINISHING THE LOW CLOUDS ACROSS SOUTHEASTERN CO...EXCEPT THE SOUTHERN PALMER DIVIDE/COS WHERE IT`S STILL UPSLOPE FLOW. AS TYPICAL WITH THESE SCENARIOS....THE STRATUS/FOG MAY HANG ON ACROSS EL PASO COUNTY UNTIL THE SOUTHWEST-WESTERLY FLOW CAN DEVELOP LATE TONIGHT OR FRIDAY MORNING. MAY NEED TO EXTEND THE WINTER WEATHER ADVISORY IN TIME ACROSS EL PASO COUNTY THROUGH NIGHT...BUT WILL LET THE DAY SHIFT HANDLE THIS IF NEEDED. METZE .LONG TERM... (FRIDAY THROUGH WEDNESDAY) ...DRY WEATHER PATTERN TO CONTINUE ACROSS SOUTHEAST COLORADO... QUIET AND STABLE WEATHER PATTERN IS EXPECTED TO CONTINUE THROUGH AT LEAST EARLY NEXT WEEK AS THE ROCKIES REMAIN ON THE EAST SIDE OF A LONGWAVE RIDGE WITH AXIS OVR THE INTERMTN REGION AND WESTERN CANADA. TEMPERATURES WILL CONTINUE TO RUN ABOUT 5-10 DEGREES ABOVE AVERAGE...WITH NO MEASURABLE PRECIP EXPECTED FOR THE NEXT SIX DAYS. RESIDUAL CLOUDS SHOULD CLEAR BY FRI MORNING...AS A LEE TROUGH RE-ESTABLISHES...AND SRLY FLOW STRENGTHENS IN ADVANCE OF ANOTHER SHORTWAVE MOVING THROUGH SD AND ERN NE. NO REAL WX CHANGE IS EXPECTED WITH THIS SYSTEM...AS THE COLDER AIR AND ANY REAL MOISTURE REMAIN WELL TO THE NE OF OUR CWA. A SHORTWAVE RIDGE WILL FOLLOW ON SATURDAY...THEN ANOTHER WEAK TROUGH WILL FOLLOW A SIMILAR TRACK THRU THE DAKOTAS ON SUN. ONCE AGAIN...THIS SYSTEM WILL NOT BRING MUCH MOISTURE TO THE AREA...MAYBE JUST AN INCREASE OF CLOUDS TO THE NRN ZONES. THE UPPER RIDGE WILL BUILD MON THRU WED...AND DRY CONDITIONS WILL LIKELY CONTINUE WITH GENERALLY SUNNY SKIES AND TEMPS OVR THE PLAINS STAYING IN THE 60S. THE PATTERN FINALLY BREAKS DOWN IN TIME FOR THANKSGIVING...AS A VERY COMPLEX SCENARIO SETS UP INVOLVING TWO BRANCHES OF THE POLAR JET. FAR TO EARLY TO SAY HOW THIS PATTERN CHANGE WILL AFFECT THE AREA...BUT THERE IS AT LEAST THE CHANCE FOR SOME MUCH NEEDED MTN SNOWS BY THE LATTER PART OF NEXT WEEK. ROSE && .AVIATION... ER SHORT TERM DISCUSSION...LIFR-IFR CEILINGS AND VISIBILITIES IN FREEZING FOG/DRIZZLE DRIZZLE SHOULD AFFECT THE KCOS TERMINAL MUCH OF THE DAY AND THROUGH THE NIGHT WHERE TEMPERATURES WILL REMAIN IN THE UPPER 20S TO LOWER 30S. IFR-MVFR CEILINGS WILL CONTINUE AT THE KPUB TERMINAL WITH AREAS OF FOG FOR TODAY...AND THEN CEILINGS AND VISIBILITIES SHOULD IMPROVE TONIGHT. VFR CLEAR BELOW 12K FT MSL CONDITIONS WILL PREVAIL AT THE KALS TERMINAL THROUGH TONIGHT. MOUNTAINS WILL BE OBSCURED IN CLOUDS AND FOG JUST WEST OF THE I-25 CORRIDOR. METZE && .PUB WATCHES/WARNINGS/ADVISORIES... WINTER WEATHER ADVISORY UNTIL 5 PM MST THIS AFTERNOON FOR COZ084- 085. && $$ 17/44 co AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL 837 PM CST THU NOV 20 2008 .DISCUSSION... 836 PM CST RADAR TRENDS OVER PAST SEVERAL HOURS HAVE CONTINUED TO DEPICT SOMEWHAT DISORGANIZED LAKE EFFECT CONVECTION ACROSS SOUTHERN LAKE MICHIGAN. SOME HIGHER REFLECTIVITY CELLS BEGINNING TO DEVELOP ACROSS FAR SOUTH LAKE MICHIGAN LAST 30 MINUTES OR SO...THOUGH STILL APPEARS MAIN LES AXIS AT THIS TIME IS ALONG EASTERN SHORE AND INTO NORTH CENTRAL INDIANA. NEW 00Z NAM IN THROUGH 48+ HOURS...AND TENDS TO KEEP MAIN CONVERGENT/QPF AXIS OFF TO THE EAST OF PORTER COUNTY...WHICH MAKES ME SUSPECT THAT OUR SNOW AMOUNTS MAY BE A BIT OVERDONE. WHILE HAVE NOWHERE NEAR ENOUGH CONFIDENCE TO DROP ONGOING WARNING FOR PORTER COUNTY...HAVE SHAVED TOTAL SNOW AMOUNTS A BIT MORE TOWARD 5 TO 7 INCHES MAX ACROSS FAR NORTHEAST PORTER COUNTY. OTHERWISE...GOING FORECAST LOOKS GOOD WITH RESPECT TO TEMPS...FLURRIES AND DECREASING CLOUDS FARTHER TO THE WEST OVERNIGHT AND HAVE MADE NO OTHER SIGNIFICANT CHANGES OTHER THAN TO BUMP WIND GUSTS ESPECIALLY THROUGH THIS EVENING. GRIDS OUT AND PUBLISHED. ZFP/WSW UPDATES OUT SHORTLY. RATZER && .PREV DISCUSSION... 340 PM CST PRIMARY FORECAST CONCERNS SURROUND LAKE EFFECT SNOW IN NORTHWEST INDIANA AS REINFORCING SHOT OF ARCTIC AIR PLUNGES SOUTH ACROSS THE WESTERN GREAT LAKES TONIGHT. MODELS SHOWING GOOD CONSISTENCY DRIVING SECONDARY UPPER LEVEL SHORTWAVE TROUGH SOUTH INTO THE OHIO VALLEY BY FRI MORNING AND CARVING OUT AN EVEN DEEPER LONG WAVE TROUGH OVER THE EASTERN U.S. THIS OPENS THE DOOR TO ANOTHER BITTERLY COLD AIRMASS FOR NOVEMBER TO SURGE SOUTH INTO THE AREA. H85 TEMPS DROP TO -14 DEG C ACROSS SRN LK MICHIGAN RESULTING IN VERY STRONG THERMAL INSTABILITY WITH LAKE WATER SURFACE TO H850 TEMP DIFFERENCES OF GREATER THAN 20 DEG C. PRIMARY CONCERN IS WHERE LES BANDS WILL SET UP WITH NW FLOW VEERING MORE NORTH AND RISING INVERSION HEIGHTS. LOCAL WRF HINTING AT SIMILAR SCENARIO AS MONDAY NIGHT/EARLY TUES WITH INTENSE MID LAKE BAND WAFFLING SOUTH ENHANCED BY MID LAKE CONVERGENCE AND THEN BLASTS ON SHORE AROUND 03Z WITH 1-3 INCH PER HOUR SNOWFALL RATES FOR A COUPLE OF HOURS. RUC SOMEWHAT SUPPORTIVE OF THIS IDEA AS WELL WITH SOMEWHAT OF AN NORTHEASTERLY BOUNDARY LAYER WIND COMPONENT ALONG THE MI SHORELINE EVIDENT AROUND 03Z. INVERSION HEIGHTS LIFT TO 12 K FEET BY 00Z THIS EVENING PER NAM FORECAST SOUNDING TIME SERIES AND STAYS THERE UNTIL ALMOST 12Z FRI. AT THIS POINT INVERSION THEN COMES CRASHING DOWN AND LOW LEVEL FLOW BECOMES ANTICYCLONIC AS SURFACE RIDGING BUILDS QUICKLY EAST INTO THE MID MISSISSIPPI AND OHIO VALLEYS DURING THE DAY FRIDAY. BEFORE THEN... LOW MOVING OFF THE MID ATLANTIC COAST AND HIGH BUILDING SOUTH ACROSS THE PLAINS ALLOWS GRADIENT WIND TO TURN FROM 320 TO MORE 340-350 MAXIMIZING FETCH DOWN THE LENGTH OF THE LAKE DURING THE NIGHT. WITH THESE FACTORS AT PLAY... WILL UPGRADE GOING LES ADVISORY TO WARNING FOR PORTER COUNTY AS EXPECT SNOWFALL TO VARY FROM 5 TO 9 INCHES ACROSS MUCH OF THE COUNTY. SNOW AMOUNTS WILL TAPER OFF SHARPLY TO THE WEST AND SOUTH AS WOULD EXPECT AN INCH OR LESS AS FAR WEST AS ALONG I-65 BUT UP TO 4 INCHES ALONG THE LAKE-PORTER COUNTY LINE IN INDIANA. INVERSION HEIGHTS LOWER TO ABOUT 3 K FEET BY 13-14Z FRI... AND CORE OF THE COLDEST AIR/LOW LEVEL THERMAL TROUGH MOVING OVERHEAD AND EAST OF NW INDIANA. WINDS ALSO BACK TO MORE NW QUICKLY FRI MORNING... WHICH WILL SHIFT ANY REMAINING MORE SIGNIFICANT LAKE EFFECT SNOW BANDS EAST OF PORTER COUNTY BY MID MORNING LEAVING A FEW FLURRIES BEHIND. ELSEWHERE RELATIVELY QUIET BUT UNSEASONABLY COLD WEATHER FOR THE NEXT 36 HOURS AS LONG WAVE TROUGH BECOMES REINFORCED ACROSS THE EASTERN U.S. UPPER PATTERN REMAINS PROGRESSIVE HOWEVER AND HEIGHTS BUILD OVER THE LOCAL AREA AS THIS TROUGH BEGINS TO LIFT TO THE EAST SAT. THIS WILL ALLOW FOR RETURN WARM AIR ADVECTION IN THE LOW LEVELS. MEANWHILE FAIRLY VIGOROUS UPPER LEVEL VORT MAX STREAKS SE IN NW FLOW ALOFT ACROSS NRN IL AND NW IND LATER ON SAT. WHILE UPPER DYNAMICS FAIRLY IMPRESSIVE WITH THIS FEATURE... LOW LEVEL MOISTURE REMAINS VERY LIMITED AND AT THIS POINT WILL FORECAST CLOUDS BUT NO PCPN. ED F SUNDAY THROUGH THURSDAY SOME MODERATION IN TEMPERATURES BACK TOWARD SEASONABLE NORMS IS EXPECTED BY SUNDAY AS LOW LEVEL SOUTHWEST FLOW STRENGTHENS IN ADVANCE OF DIGGING NORTHERN PLAINS UPPER TROUGH. DESPITE FAIRLY STRONG WARM ADVECTION FORCING...DRY CONDITIONS ARE EXPECTED TO PERSIST DURING THE DAY ON SUNDAY WITH COLUMN INITIALLY QUITE DRY. DESPITE INCREASING HIGH/MID CLOUDINESS ON SUNDAY...TEMPERATURES SHOULD REACH INTO THE MID 40S MOST LOCATIONS. HAVE MAINTAINED MENTION OF CHANCE RAIN/SNOW SHOWERS SUNDAY NIGHT AS UPPER TROUGH AXIS APPROACHES WITH FORECAST SOUNDINGS STILL MARGINAL IN TERMS OF PRECIP TYPE WITH LOW LEVEL WET BULB TEMPERATURES RIGHT AROUND FREEZING. FAIRLY GOOD AGREEMENT IN REGARDS TO UPPER TROUGH EVOLUTION BETWEEN GFS/ECMWF INTO MONDAY...WITH DRYING CONDITIONS EXPECTED MONDAY AFTERNOON AS THE UPPER LOW MOVES OFF TO THE EAST. QUIET CONDITIONS EXPECTED TUESDAY/WEDNESDAY...AND NEXT CONCERN WILL BE POTENTIAL OF NEXT SYSTEM TO AFFECT THE AREA TOWARD THE END OF THE WEEK. WITH INCREASING SPREAD IN NCEP ENSEMBLES TOWARD THE END OF THE WEEK...LARGE RUN TO RUN DEVIATIONS...AND TIMING UNCERTAINTIES AMONG MEDIUM RANGE MODELS...WILL KEEP THANKSGIVING DRY AT THIS POINT. NDM && .AVIATION... 00Z TAFS...VFR CIGS 4-6KFT WILL CONTINUE THIS EVENING BUT MODELS DIFFER ON HOW SOON THEY WILL BEGIN TO SCATTER OUT. ALREADY SEEING BACK EDGE OF CLOUD COVER ACROSS NW IL BUT STILL A THICK DECK ACROSS WI MOVING SOUTH. HAVE CONTINUED SIMILAR TIMING OF PREVIOUS FORECAST WITH CIGS SCATTERING OUT AROUND/SHORTLY AFTER MIDNIGHT. LAKE EFFECT SNOW SHOWERS TO AFFECT AREAS EAST OF GYY...BUT A FEW FLURRIES POSSIBLE THERE ALONG WITH CIGS LASTING INTO FRIDAY MORNING. NORTHWEST WINDS APPEAR TO BE TRICKY AGAIN TONIGHT THIS EVENING WITH GUSTS INTO THE MID 20KTS AT TIMES THEN NO GUSTS. HAVE KEPT GUSTS IN THE LOW 20KTS THRU EARLY MORNING THEN AS CLOUDS SCATTER SHOULD SEE GUSTS DIMINISH WITH A PREVAILING 10-15KT WIND. WINDS SLOWLY TURN WESTERLY THROUGH THE DAY FRIDAY...PERHAPS A FEW HIGHER GUSTS MIDDAY...THEN WIND DIMINISH UNDER 10KTS WITH SUNSET. CMS && .MARINE... 141 PM CST LARGE SPRAWLING HIGH PRESSURE CENTERED NEAR LAKE WINNEPEG THIS AFTERNOON...COMBINED WITH DEEP LOW PRESSURE OVER THE CANADIAN MARITIMES...WAS PRODUCING GALE FORCE NORTHWEST WINDS OVER LAKE MICHIGAN. THE NORTHWEST GALES WILL CONTINUE THROUGH MOST OF THE NIGHT. THE HIGH WILL MOVE SOUTHEAST TO THE LOWER MISSISSIPPI AND LOWER OHIO RIVER VALLEYS BY FRIDAY EVENING...ALLOWING WINDS TO SLOWLY SUBSIDE. THE HIGH WILL CONTINUE MOVING SOUTHEAST...REACHING THE CAROLINAS BY SUNDAY. MEANWHILE A WEAK TROF OF LOW PRESSURE WILL DEVELOP OVER THE PLAINS FRIDAY...THEN DRIFT SLOWLY EAST TOWARD THE MID AND UPPER MISSISSIPPI VALLEY BY SUNDAY. LOW PRESSURE WILL DEVELOP OVER THE WESTERN GREAT LAKES SUNDAY NIGHT. THE LOW WILL DEEPEN AS IT MOVES TO THE EASTERN GREAT LAKES MONDAY. THIS WILL BRING A RETURN OF STRONG...POSSIBLY GALE FORCE... NORTHWEST WINDS TO LAKE MICHIGAN MONDAY. ALLSOPP && .LOT WATCHES/WARNINGS/ADVISORIES... IL...NONE. IN...LAKE EFFECT SNOW WARNING...INZ002 UNTIL 9 AM FRIDAY. LM...GALE WARNING...LMZ080-LMZ261-LMZ362-LMZ364-LMZ366-LMZ563-LMZ565- LMZ567-LMZ669-LMZ671-LMZ673-LMZ675-LMZ744-LMZ745-LMZ777- LMZ779-LMZ868-LMZ870-LMZ872-LMZ874-LMZ876-LMZ878 UNTIL 3 AM FRIDAY. SMALL CRAFT ADVISORY...NEARSHORE WINTHROP HARBOR TO GARY IN UNTIL 6 PM FRIDAY. SMALL CRAFT ADVISORY...LMZ744-LMZ745...3 AM FRIDAY TO 6 PM FRIDAY. && $$ il AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL 542 PM CST THU NOV 20 2008 .DISCUSSION... 340 PM CST PRIMARY FORECAST CONCERNS SURROUND LAKE EFFECT SNOW IN NORTHWEST INDIANA AS REINFORCING SHOT OF ARCTIC AIR PLUNGES SOUTH ACROSS THE WESTERN GREAT LAKES TONIGHT. MODELS SHOWING GOOD CONSISTENCY DRIVING SECONDARY UPPER LEVEL SHORTWAVE TROUGH SOUTH INTO THE OHIO VALLEY BY FRI MORNING AND CARVING OUT AN EVEN DEEPER LONG WAVE TROUGH OVER THE EASTERN U.S. THIS OPENS THE DOOR TO ANOTHER BITTERLY COLD AIRMASS FOR NOVEMBER TO SURGE SOUTH INTO THE AREA. H85 TEMPS DROP TO -14 DEG C ACROSS SRN LK MICHIGAN RESULTING IN VERY STRONG THERMAL INSTABILITY WITH LAKE WATER SURFACE TO H850 TEMP DIFFERENCES OF GREATER THAN 20 DEG C. PRIMARY CONCERN IS WHERE LES BANDS WILL SET UP WITH NW FLOW VEERING MORE NORTH AND RISING INVERSION HEIGHTS. LOCAL WRF HINTING AT SIMILAR SCENARIO AS MONDAY NIGHT/EARLY TUES WITH INTENSE MID LAKE BAND WAFFLING SOUTH ENHANCED BY MID LAKE CONVERGENCE AND THEN BLASTS ON SHORE AROUND 03Z WITH 1-3 INCH PER HOUR SNOWFALL RATES FOR A COUPLE OF HOURS. RUC SOMEWHAT SUPPORTIVE OF THIS IDEA AS WELL WITH SOMEWHAT OF AN NORTHEASTERLY BOUNDARY LAYER WIND COMPONENT ALONG THE MI SHORELINE EVIDENT AROUND 03Z. INVERSION HEIGHTS LIFT TO 12 K FEET BY 00Z THIS EVENING PER NAM FORECAST SOUNDING TIME SERIES AND STAYS THERE UNTIL ALMOST 12Z FRI. AT THIS POINT INVERSION THEN COMES CRASHING DOWN AND LOW LEVEL FLOW BECOMES ANTICYCLONIC AS SURFACE RIDGING BUILDS QUICKLY EAST INTO THE MID MISSISSIPPI AND OHIO VALLEYS DURING THE DAY FRIDAY. BEFORE THEN... LOW MOVING OFF THE MID ATLANTIC COAST AND HIGH BUILDING SOUTH ACROSS THE PLAINS ALLOWS GRADIENT WIND TO TURN FROM 320 TO MORE 340-350 MAXIMIZING FETCH DOWN THE LENGTH OF THE LAKE DURING THE NIGHT. WITH THESE FACTORS AT PLAY... WILL UPGRADE GOING LES ADVISORY TO WARNING FOR PORTER COUNTY AS EXPECT SNOWFALL TO VARY FROM 5 TO 9 INCHES ACROSS MUCH OF THE COUNTY. SNOW AMOUNTS WILL TAPER OFF SHARPLY TO THE WEST AND SOUTH AS WOULD EXPECT AN INCH OR LESS AS FAR WEST AS ALONG I-65 BUT UP TO 4 INCHES ALONG THE LAKE-PORTER COUNTY LINE IN INDIANA. INVERSION HEIGHTS LOWER TO ABOUT 3 K FEET BY 13-14Z FRI... AND CORE OF THE COLDEST AIR/LOW LEVEL THERMAL TROUGH MOVING OVERHEAD AND EAST OF NW INDIANA. WINDS ALSO BACK TO MORE NW QUICKLY FRI MORNING... WHICH WILL SHIFT ANY REMAINING MORE SIGNIFICANT LAKE EFFECT SNOW BANDS EAST OF PORTER COUNTY BY MID MORNING LEAVING A FEW FLURRIES BEHIND. ELSEWHERE RELATIVELY QUIET BUT UNSEASONABLY COLD WEATHER FOR THE NEXT 36 HOURS AS LONG WAVE TROUGH BECOMES REINFORCED ACROSS THE EASTERN U.S. UPPER PATTERN REMAINS PROGRESSIVE HOWEVER AND HEIGHTS BUILD OVER THE LOCAL AREA AS THIS TROUGH BEGINS TO LIFT TO THE EAST SAT. THIS WILL ALLOW FOR RETURN WARM AIR ADVECTION IN THE LOW LEVELS. MEANWHILE FAIRLY VIGOROUS UPPER LEVEL VORT MAX STREAKS SE IN NW FLOW ALOFT ACROSS NRN IL AND NW IND LATER ON SAT. WHILE UPPER DYNAMICS FAIRLY IMPRESSIVE WITH THIS FEATURE... LOW LEVEL MOISTURE REMAINS VERY LIMITED AND AT THIS POINT WILL FORECAST CLOUDS BUT NO PCPN. ED F SUNDAY THROUGH THURSDAY SOME MODERATION IN TEMPERATURES BACK TOWARD SEASONABLE NORMS IS EXPECTED BY SUNDAY AS LOW LEVEL SOUTHWEST FLOW STRENGTHENS IN ADVANCE OF DIGGING NORTHERN PLAINS UPPER TROUGH. DESPITE FAIRLY STRONG WARM ADVECTION FORCING...DRY CONDITIONS ARE EXPECTED TO PERSIST DURING THE DAY ON SUNDAY WITH COLUMN INITIALLY QUITE DRY. DESPITE INCREASING HIGH/MID CLOUDINESS ON SUNDAY...TEMPERATURES SHOULD REACH INTO THE MID 40S MOST LOCATIONS. HAVE MAINTAINED MENTION OF CHANCE RAIN/SNOW SHOWERS SUNDAY NIGHT AS UPPER TROUGH AXIS APPROACHES WITH FORECAST SOUNDINGS STILL MARGINAL IN TERMS OF PRECIP TYPE WITH LOW LEVEL WET BULB TEMPERATURES RIGHT AROUND FREEZING. FAIRLY GOOD AGREEMENT IN REGARDS TO UPPER TROUGH EVOLUTION BETWEEN GFS/ECMWF INTO MONDAY...WITH DRYING CONDITIONS EXPECTED MONDAY AFTERNOON AS THE UPPER LOW MOVES OFF TO THE EAST. QUIET CONDITIONS EXPECTED TUESDAY/WEDNESDAY...AND NEXT CONCERN WILL BE POTENTIAL OF NEXT SYSTEM TO AFFECT THE AREA TOWARD THE END OF THE WEEK. WITH INCREASING SPREAD IN NCEP ENSEMBLES TOWARD THE END OF THE WEEK...LARGE RUN TO RUN DEVIATIONS...AND TIMING UNCERTAINTIES AMONG MEDIUM RANGE MODELS...WILL KEEP THANKSGIVING DRY AT THIS POINT. NDM && .AVIATION... 00Z TAFS...VFR CIGS 4-6KFT WILL CONTINUE THIS EVENING BUT MODELS DIFFER ON HOW SOON THEY WILL BEGIN TO SCATTER OUT. ALREADY SEEING BACK EDGE OF CLOUD COVER ACROSS NW IL BUT STILL A THICK DECK ACROSS WI MOVING SOUTH. HAVE CONTINUED SIMILAR TIMING OF PREVIOUS FORECAST WITH CIGS SCATTERING OUT AROUND/SHORTLY AFTER MIDNIGHT. LAKE EFFECT SNOW SHOWERS TO AFFECT AREAS EAST OF GYY...BUT A FEW FLURRIES POSSIBLE THERE ALONG WITH CIGS LASTING INTO FRIDAY MORNING. NORTHWEST WINDS APPEAR TO BE TRICKY AGAIN TONIGHT THIS EVENING WITH GUSTS INTO THE MID 20KTS AT TIMES THEN NO GUSTS. HAVE KEPT GUSTS IN THE LOW 20KTS THRU EARLY MORNING THEN AS CLOUDS SCATTER SHOULD SEE GUSTS DIMINISH WITH A PREVAILING 10-15KT WIND. WINDS SLOWLY TURN WESTERLY THROUGH THE DAY FRIDAY...PERHAPS A FEW HIGHER GUSTS MIDDAY...THEN WIND DIMINISH UNDER 10KTS WITH SUNSET. CMS && .MARINE... 141 PM CST LARGE SPRAWLING HIGH PRESSURE CENTERED NEAR LAKE WINNEPEG THIS AFTERNOON...COMBINED WITH DEEP LOW PRESSURE OVER THE CANADIAN MARITIMES...WAS PRODUCING GALE FORCE NORTHWEST WINDS OVER LAKE MICHIGAN. THE NORTHWEST GALES WILL CONTINUE THROUGH MOST OF THE NIGHT. THE HIGH WILL MOVE SOUTHEAST TO THE LOWER MISSISSIPPI AND LOWER OHIO RIVER VALLEYS BY FRIDAY EVENING...ALLOWING WINDS TO SLOWLY SUBSIDE. THE HIGH WILL CONTINUE MOVING SOUTHEAST...REACHING THE CAROLINAS BY SUNDAY. MEANWHILE A WEAK TROF OF LOW PRESSURE WILL DEVELOP OVER THE PLAINS FRIDAY...THEN DRIFT SLOWLY EAST TOWARD THE MID AND UPPER MISSISSIPPI VALLEY BY SUNDAY. LOW PRESSURE WILL DEVELOP OVER THE WESTERN GREAT LAKES SUNDAY NIGHT. THE LOW WILL DEEPEN AS IT MOVES TO THE EASTERN GREAT LAKES MONDAY. THIS WILL BRING A RETURN OF STRONG...POSSIBLY GALE FORCE... NORTHWEST WINDS TO LAKE MICHIGAN MONDAY. ALLSOPP && .LOT WATCHES/WARNINGS/ADVISORIES... IL...NONE. IN...LAKE EFFECT SNOW WARNING...INZ002 UNTIL 9 AM FRIDAY. LM...GALE WARNING...LMZ080-LMZ261-LMZ362-LMZ364-LMZ366-LMZ563-LMZ565- LMZ567-LMZ669-LMZ671-LMZ673-LMZ675-LMZ744-LMZ745-LMZ777- LMZ779-LMZ868-LMZ870-LMZ872-LMZ874-LMZ876-LMZ878 UNTIL 3 AM FRIDAY. SMALL CRAFT ADVISORY...NEARSHORE WINTHROP HARBOR TO GARY IN UNTIL 6 PM FRIDAY. SMALL CRAFT ADVISORY...LMZ744-LMZ745...3 AM FRIDAY TO 6 PM FRIDAY. && $$ il AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LINCOLN IL 112 PM CST THU NOV 20 2008 .DISCUSSION... ISSUED 111 PM CST THU NOV 20 2008 UPDATED THE FORECAST THIS AFTERNOON TO ADD A CHANCE OF LIGHT SNOW SHOWERS AND FLURRIES ACROSS SE ILLINOIS TOO. ALREADY HAVE A CHANCE IN FOR CENTRAL IL THIS AFTERNOON. A FEW LIGHT SNOW SHOWERS AND FLURRIES COULD LINGER INTO EARLY EVENING ESPECIALLY OVER EASTERN IL AS A SHORT WAVE/TROF OVER CENTRAL IL AT MID AFTERNOON PASSES THRU SE IL DURING EARLY EVENING. CLOUDY TO MOSTLY CLOUDY SKIES AND BLUSTERY NW WINDS OF 10 TO 20 MPH AND GUSTS OF 20 TO 30 MPH. TEMPERATURES NEARLY STEADY IN THE LOWER TO MIDDLE 30S THIS AFTERNOON WITH WIND CHILL VALUES IN THE LOW TO MID 20S. HUETTL && .AVIATION... ISSUED 1145 AM CST THU NOV 20 2008 VFR CONDITIONS SHOULD CONTINUE ACROSS THE CENTRAL ILLINOIS TERMINALS THROUGH FRIDAY. VFR CEILINGS OF 3 TO 4K FT OVER CENTRAL IL THIS AFTERNOON WILL SCATTERED FLURRIES POSSIBLE BUT VSBYS STILL ABOVE 5 MILES. LOW CLOUDS EXPECTED TO SCATTER OUT FROM WEST TO EAST DURING MID AND LATE EVENING AND EVENTUALLY CLEAR OUT DURING OVERNIGHT. LOW CLOUDS AND SCATTERED FLURRIES DUE TO ELONGATED SHORT WAVE OVER IA AND NORTHERN IL THAT MOVES INTO SE IL BY EARLY EVENING. 1049 MB CANADIAN HIGH PRESSURE ALONG THE MANITOBA AND SASKETCHEWAN PROVINCE LINE AND RIDGING SOUTHWARD ACROSS THE HIGH PLAINS WILL MOVE OVER THE MS RIVER VALLEY BY 18Z/FRI. THIS WILL ENSURE CLEAR SKIES ACROSS CENTRAL IL FRIDAY. BRISK NW WINDS OF 10 TO 20 KTS WITH GUSTS IN THE 20S WILL SUBSIDE TO AROUND 10 KTS BY OVERNIGHT AND CONTINUE FRIDAY. HUETTL && .PREV DISCUSSION... ISSUED 1000 AM CST THU NOV 20 2008 FORECAST AGAIN LOOKS ON TRACK TODAY AND ONLY DID MINOR TWEAKS TO THE HOURLY TEMPERATURE...DEWPOINT AND SKY GRIDS. MOSTLY CLOUDY TO OVERCAST SKIES TODAY WITH BRISK NORTHWEST WINDS 10 TO 20 MPH AND GUSTS IN THE 20S. MUCH COOLER HIGHS IN THE MID TO UPPER 30S. LATE MORNING SURFACE MAP SHOWS STRONG 1049 MB CANADIAN HIGH PRESSURE ALONG THE SASKETCHEWAN AND MANITOBA LINE AND RIDGING SOUTHWARD ACROSS THE HIGH PLAINS. THIS STRONG HIGH PRESSURE HAS PUSHED THE COLD FRONT WELL SOUTH OF IL TO ALONG THE SOUTHERN TN BORDER. NEARLY OVERCAST STRATOCUMULUS CLOUD DECK COVERS IL WITH CEILINGS AROUND 4K FT. TEMPERATURES WERE MOSTLY IN THE MID 30S BUT RANGED FROM 32F IN BLOOMINGTON TO 38F IN LAWRENCEVILLE. NNW WINDS 10 TO 15 MPH WITH GUSTS OF 18 TO 25 MPH WERE PRODUCING WIND CHILLS IN THE 20S. ALOFT A LARGE UPPER LEVEL LOW/TROF WAS OVER EASTERN CANADA AND COVERING THE NE HALF OF THE U.S. WHILE UPPER LEVEL RIDGE WAS OVER THE ROCKIES. IL REMAINS IN A NW UPPER LEVEL FLOW. SHORT WAVE WAS PUSHING SOUTHWARD ACROSS MN/WI TOWARD THE NORTHERN IA/IL BORDER. 12Z RUC...NAM AND SREF MODELS ARE SIMILAR IN TRACKING A SHORT WAVE SOUTHWARD ACROSS CENTRAL IL DURING THIS AFTERNOON AND SE IL EARLY THIS EVENING. LIMITED MOISTURE WITH THIS FEATURE SO JUST EXPECTING SCATTERED FLURRIES THIS AFTERNOON AND EARLY EVENING. LOW CLOUDS WILL DECREASE FROM THE WEST DURING TONIGHT AS STRONG CANADIAN HIGH PRESSURE DRIFTS EAST TOWARD THE MS VALLEY BY FRI MORNING. WILL BE A COLD NIGHT TONIGHT WITH LOWS IN THE MID TO UPPER TEENS. BRISK NW WINDS COMBINED WITH LOW CLOUDS WILL LIMIT HEATING TODAY WITH TEMPERATURES NOT CLIMBING MUCH MORE THAN A DEGREE OR TWO. HIGHS IN THE MID 30S OVER CENTRAL IL AND UPPER 30S IN SE IL WITH LAWRENCEVILLE NEAR 40F. HUETTL && .ILX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ il AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LINCOLN IL 1146 AM CST THU NOV 20 2008 .DISCUSSION... ISSUED 1000 AM CST THU NOV 20 2008 FORECAST AGAIN LOOKS ON TRACK TODAY AND ONLY DID MINOR TWEAKS TO THE HOURLY TEMPERATURE...DEWPOINT AND SKY GRIDS. MOSTLY CLOUDY TO OVERCAST SKIES TODAY WITH BRISK NORTHWEST WINDS 10 TO 20 MPH AND GUSTS IN THE 20S. MUCH COOLER HIGHS IN THE MID TO UPPER 30S. LATE MORNING SURFACE MAP SHOWS STRONG 1049 MB CANADIAN HIGH PRESSURE ALONG THE SASKETCHEWAN AND MANITOBA LINE AND RIDGING SOUTHWARD ACROSS THE HIGH PLAINS. THIS STRONG HIGH PRESSURE HAS PUSHED THE COLD FRONT WELL SOUTH OF IL TO ALONG THE SOUTHERN TN BORDER. NEARLY OVERCAST STRATOCUMULUS CLOUD DECK COVERS IL WITH CEILINGS AROUND 4K FT. TEMPERATURES WERE MOSTLY IN THE MID 30S BUT RANGED FROM 32F IN BLOOMINGTON TO 38F IN LAWRENCEVILLE. NNW WINDS 10 TO 15 MPH WITH GUSTS OF 18 TO 25 MPH WERE PRODUCING WIND CHILLS IN THE 20S. ALOFT A LARGE UPPER LEVEL LOW/TROF WAS OVER EASTERN CANADA AND COVERING THE NE HALF OF THE U.S. WHILE UPPER LEVEL RIDGE WAS OVER THE ROCKIES. IL REMAINS IN A NW UPPER LEVEL FLOW. SHORT WAVE WAS PUSHING SOUTHWARD ACROSS MN/WI TOWARD THE NORTHERN IA/IL BORDER. 12Z RUC...NAM AND SREF MODELS ARE SIMILAR IN TRACKING A SHORT WAVE SOUTHWARD ACROSS CENTRAL IL DURING THIS AFTERNOON AND SE IL EARLY THIS EVENING. LIMITED MOISTURE WITH THIS FEATURE SO JUST EXPECTING SCATTERED FLURRIES THIS AFTERNOON AND EARLY EVENING. LOW CLOUDS WILL DECREASE FROM THE WEST DURING TONIGHT AS STRONG CANADIAN HIGH PRESSURE DRIFTS EAST TOWARD THE MS VALLEY BY FRI MORNING. WILL BE A COLD NIGHT TONIGHT WITH LOWS IN THE MID TO UPPER TEENS. BRISK NW WINDS COMBINED WITH LOW CLOUDS WILL LIMIT HEATING TODAY WITH TEMPERATURES NOT CLIMBING MUCH MORE THAN A DEGREE OR TWO. HIGHS IN THE MID 30S OVER CENTRAL IL AND UPPER 30S IN SE IL WITH LAWRENCEVILLE NEAR 40F. HUETTL && .AVIATION... ISSUED 1145 AM CST THU NOV 20 2008 VFR CONDITIONS SHOULD CONTINUE ACROSS THE CENTRAL ILLINOIS TERMINALS THROUGH FRIDAY. VFR CEILINGS OF 3 TO 4K FT OVER CENTRAL IL THIS AFTERNOON WILL SCATTERED FLURRIES POSSIBLE BUT VSBYS STILL ABOVE 5 MILES. LOW CLOUDS EXPECTED TO SCATTER OUT FROM WEST TO EAST DURING MID AND LATE EVENING AND EVENTUALLY CLEAR OUT DURING OVERNIGHT. LOW CLOUDS AND SCATTERED FLURRIES DUE TO ELONGATED SHORT WAVE OVER IA AND NORTHERN IL THAT MOVES INTO SE IL BY EARLY EVENING. 1049 MB CANADIAN HIGH PRESSURE ALONG THE MANITOBA AND SASKETCHEWAN PROVINCE LINE AND RIDGING SOUTHWARD ACROSS THE HIGH PLAINS WILL MOVE OVER THE MS RIVER VALLEY BY 18Z/FRI. THIS WILL ENSURE CLEAR SKIES ACROSS CENTRAL IL FRIDAY. BRISK NW WINDS OF 10 TO 20 KTS WITH GUSTS IN THE 20S WILL SUBSIDE TO AROUND 10 KTS BY OVERNIGHT AND CONTINUE FRIDAY. HUETTL && .PREV DISCUSSION... ISSUED 307 AM CST THU NOV 20 2008 COLD FRONT PUSHED THROUGH THE SOUTHEAST CWA EARLY LAST EVENING AND WAS NOW CENTERED CLOSE TO THE OHIO RIVER. STRATOCUMULUS DECK WAS LAGGING BEHIND A BIT...BUT NOW COVERED THE NORTHWEST 2/3 OF THE CWA. WATER VAPOR IMAGERY SHOWED THE NEXT IN THE SHORTWAVE SERIES APPROACHING NORTHWEST NORTH DAKOTA. ISSUES OF THE DAY INCLUDE SKY COVER FOR TODAY...AND THE EFFECTS OF THE SUNDAY/MONDAY STORM SYSTEM OVER THE FORECAST AREA. SHORT TERM...TODAY THROUGH SATURDAY... SHORTWAVE TO QUICKLY MOVE SOUTHEAST ACROSS THE CWA THIS AFTERNOON AND EVENING. WITH DRIER LOW LEVELS...DO NOT EXPECT MUCH MORE THAN FLURRIES FROM THIS FEATURE. CLOUDS WILL BE SLOWER TO ERODE THOUGH...AS INVERSION TIGHTENS AROUND 850 MB. MUCH OF THE DAY EXPECTED TO BE CLOUDY...WITH SOME SLOW IMPROVEMENT TOWARD LATE AFTERNOON. MORE RAPID CLEARING EXPECTED DURING THE EVENING HOURS. CANADIAN HIGH PRESSURE TO BUILD SOUTH THE NEXT 24 HOURS...AND SHOULD BE CENTERED IN MISSOURI BY MIDDAY FRIDAY AND ACROSS THE TENNESSEE VALLEY FRIDAY NIGHT. THIS WILL PROVIDE A CHALLENGE TO A SHORTWAVE WHICH WILL DIVE SOUTHEAST OUT THE NORTHERN ROCKIES. THIS FEATURE IS EXPECTED TO WEAKEN AS IT MOVES OVER THE CWA...AND ANY MEASURABLE PRECIPITATION SHOULD REMAIN TO OUR NORTHWEST. DID ADD A FEW FLURRIES FOR AREAS WEST OF I-55 DURING THE MORNING. LONG TERM...SUNDAY THROUGH WEDNESDAY... LONGER RANGE MODELS IN REASONABLE AGREEMENT WITH CUTOFF UPPER LOW WHICH WILL MOVE INTO THE GREAT LAKES REGION EARLY NEXT WEEK. ASSOCIATED SURFACE COLD FRONT EXPECTED TO MOVE ACROSS ILLINOIS SUNDAY NIGHT. REMOVED RAIN CHANCES SUNDAY MORNING AND CONVERTED THE AFTERNOON TO SILENT 20 POPS...AS THE AIR WILL BE QUITE DRY INITIALLY AND IT WILL TAKE MUCH OF THE DAY TO GET SUFFICIENTLY MOIST. SHOULD BE A FAIR AMOUNT OF SUNSHINE EVEN...ESPECIALLY IN THE MORNING BEFORE HIGH CLOUDS ARRIVE AND THICKEN. ONCE PRECIPITATION FORMS DURING THE EVENING...IT SHOULD BE RATHER LIGHT AND MAINLY ACROSS THE EASTERN CWA. MODEL SOUNDINGS SHOW MUCH OF THIS TO BE RAIN. MAY SEE SOME WRAPAROUND FLURRIES LATER MONDAY THOUGH. CUTOFF LOW TO BE SLOW TO PUSH EAST ACROSS THE REGION THROUGH MIDWEEK. DID NOT MAKE ANY CHANGES IN THE FORECAST AT THAT TIME RANGE THOUGH. GEELHART && .ILX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ il AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LINCOLN IL 1155 AM CST WED NOV 19 2008 .DISCUSSION... ISSUED 955 AM CST WED NOV 19 2008 FORECAST IS IN GOOD SHAPE TODAY AND JUST INCREASED AMOUNT OF SUNSHINE AND WINDS A BIT TODAY. MOSTLY SUNNY AND BREEZY SSW WINDS WITH SEASONABLE HIGHS IN THE UPPER 40S AND LOWER 50S. 15Z/9 AM SURFACE MAP SHOWS 1009 MB LOW PRESSURE OVER LAKE SUPERIOR WITH A COLD FRONT EXTENDING SW ACROSS CENTRAL WI...SE IA AND CENTRAL KS. 1032 MB HIGH PRESSURE WAS ACROSS THE SE STATES. FAIRLY TIGHT PRESSURE GRADIENT GENERATE BREEZY SSW WINDS OF 10 TO 20 MPH WITH GUSTS OF 20 TO 30 MPH ACROSS CENTRAL/SE IL. AMPLE SUNSHINE ACROSS IL WITH LOW CLOUDS EAST OVER INDIANA FROM I-65 EAST AND NORTH OVER MN AND CENTRAL/NORTHERN WI. BAND OF CIRRUS CLOUDS OVER SOUTHERN IA INTO CENTRAL IL. TEMPS OVER CENTRAL/SE IL WERE IN THE MID TO UPPER 30S. DEWPOINT ONLY IN THE LOW TO MID 20S SO LOW LEVELS ARE PRETTY DRY. IL REMAINED IN A QUIET NW UPPER LEVEL FLOW WITH UPPER LEVEL RIDGE OVER MEXICO AND SW STATES WHILE UPPER LEVEL LOW/TROF OVER HUDSON BAY...EASTERN CANADA AND NEW ENGLAND. 12Z RUC...NAM AND SREF MODELS BRING THE COLD FRONT OVER SE IOWA SE THROUGH CENTRAL IL DURING THIS AFTERNOON AND SE IL EARLY THIS EVENING. BREEZY SSW WINDS SHIFT WEST AND DECREASE DURING THE AFTERNOON WITH RELAXING PRESSURE GRADIENT. FRONT TO PASS THROUGH DRY WITH VERY LITTLE MOISTURE TO WORK WITH AND UPPER LEVEL DYNAMICS STAYING OVER THE GREAT LAKES. MOSTLY SUNNY SKIES TO PREVAIL THROUGH THE AFTERNOON WITH BANDS OF CIRRUS CLOUDS AND FEW CU/ALTCU CLOUDS. BROKEN TO OVERCAST LOW CLOUDS STAYING EAST OF IL OVER INDIANA. LOW CLOUDS OVER MN AND CENTRAL WI TO DROP SOUTHWARD TOWARD PEORIA BY MIDNIGHT. 850 MB TEMPS ELEVATE TO 4 TO 8C THIS AFTERNOON. HIGHS BACK TO NORMAL TODAY FROM 45 TO 50F (COOLEST NE OF I-74) WITH LOWER 50S SW OF LINCOLN. HUETTL && .AVIATION... ISSUED 1155 AM CST WED NOV 19 2008 VFR CONDITIONS WILL CONTINUE THROUGH THIS EVENING ACROSS CENTRAL IL TERMINALS. BREEZY SW WINDS 10 TO 15 KTS AND GUSTS OF 20 TO 25 KTS TURN WNW AFTER THE PASSAGE OF A COLD FRONT AND WEAKEN A BIT DURING MID AFTERNOON WITH TEMPORARY RELAXING PRESSURE GRADIENT. COLD FRONT IN FAR NW IL NEAR GALESBURG WILL MOVE SE TO THE IL RIVER/PIA BY 20Z AND CMI/DEC 22-23Z. COLD FRONT WILL PASS THROUGH CENTRAL IL DRY WITH MOSTLY CLEAR SKIES INTO THIS EVENING WITH FEW TO SCATTERED 5 TO 9K FT CLOUDS AND BANDS OF CIRRUS. CANOPY OF LOW CLOUDS OF 1.5 TO 2K FT DROPPING SOUTHWARD INTO NORTHERN IA AND SOUTHERN WI. 12Z NAM MODEL TIME HEIGHT/RH CROSS SECTIONS SHOW THESE BROKEN TO OVERCAST LOW CLOUDS WITH MVFR CEILINGS DROPPING SOUTH TO PIA BY 05Z AND SPI/DEC BY 08Z AND LINGER THROUGH THU. NW WINDS 12 TO 15 KTS TONIGHT AND NNW WINDS 14 TO 18 KTS AND GUSTS NEAR 25 KTS THU. COULD BE A FEW FLURRIES THU ESPECIALLY THU AFTERNOON. HUETTL && .PREV DISCUSSION... ISSUED 248 AM CST WED NOV 19 2008 HIGH PRESSURE RIDGE SLIDING OFF TO OUR EAST EARLY THIS MORNING... WITH SOUTHERLY WINDS PICKING UP ACROSS THE WESTERN HALF OF THE CWA. THIS HAS RESULTED IN TEMPERATURES CREEPING UPWARD AS THE NIGHT AS PROGRESSED. NEXT FEATURE OF INTEREST IS A COLD FRONT TO OUR NORTHWEST...CURRENTLY EXTENDING FROM CENTRAL MINNESOTA INTO NEBRASKA. FORECAST ISSUES OF THE DAY ARE WITH THE CLOUDINESS ASSOCIATED WITH THIS FRONT...AS WELL AS THE CONTINUED DILEMMA OF THE STORM SYSTEM EXPECTED TO AFFECT THE MIDWEST SUNDAY INTO MONDAY. SHORT TERM...TODAY THROUGH SATURDAY... WARM ADVECTION TO RAMP UP TODAY AHEAD OF THE COLD FRONT...AS TEMPERATURES REACH INTO THE UPPER 40S AND LOWER 50S. MODELS IN AGREEMENT ABOUT BRINGING THIS FRONT THROUGH MOST OF THE CWA BY EARLY EVENING...AND AS HAS BEEN THE RECENT TREND...IT IS EXPECTED TO BE A DRY PASSAGE. TIME-HEIGHT CROSS SECTIONS INDICATING LOWER LEVEL CLOUDS EXPECTED TO BE FAIRLY WIDESPREAD BEHIND THE FRONT...A TREND NOTED EARLY THIS MORNING ACROSS NORTHERN PORTIONS OF MINNESOTA AND NORTH DAKOTA. INCREASED CLOUD COVER IN THE FORECAST FOR TONIGHT AND THURSDAY AS A RESULT. CANADIAN HIGH PRESSURE TO BUILD SOUTH INTO THE MID-MISSISSIPPI VALLEY LATE THURSDAY INTO FRIDAY...WITH DRIER AIR ALOFT RESULTING IN MOSTLY CLEAR SKIES BY FRIDAY MORNING. NAM MODEL BECOMES THE OUTLIER AT THIS POINT WITH THE CENTER OF THE HIGH STILL IN SOUTHERN MINNESOTA BY FRIDAY EVENING...WHILE THE OTHER MODELS HAVE IT JUST SOUTH OF ILLINOIS. THIS IMPACTS THE EXPECTED POSITIONING OF THE NEXT SHORTWAVE...WHICH WILL BE MOVING OUT OF THE PACIFIC NORTHWEST ON FRIDAY TOWARD THE MIDWEST. GFS IS MOST PROGRESSIVE BY BRINGING THIS FEATURE OVER CENTRAL ILLINOIS BY SATURDAY MORNING... WHILE ECMWF LAGS A BIT BEHIND IN IOWA AND THE NAM HAS IT STILL BACK IN NEBRASKA. IN ANY EVENT...IT WILL HAVE A TOUGH TIME AS IT ENCOUNTERS THE RATHER DRY AIR OVER THE REGION...AND IS ONLY EXPECTED TO PRODUCE A FEW SPRINKLES OR FLURRIES AT BEST. LONG TERM...SUNDAY THROUGH TUESDAY... LONGER RANGE MODELS STARTING TO COME INTO BETTER AGREEMENT WITH THE ORGANIZATION OF THE STORM SYSTEM LATE IN THE WEEKEND. ECMWF IS A BIT FURTHER SOUTH WITH THE CENTER OF THE SURFACE AND UPPER LEVEL LOW...BUT BOTH HAVE THE ASSOCIATED COLD FRONT MOVING ACROSS THE CWA SUNDAY EVENING. ECMWF IS ALSO THE DRIER OF THE TWO MODELS...KEEPING MUCH OF THE PRECIPITATION WITH THE FRONT JUST TO OUR SOUTH. STILL A FAIR AMOUNT OF DRY AIR THAT WILL NEED TO BE OVERCOME ON SUNDAY FOR ANY DECENT PRECIPITATION CHANCES. HOWEVER... THIS PART OF THE FORECAST WAS UPDATED TO INCREASE THE CLOUD COVERAGE. GEELHART && .ILX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ il AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NORTHERN INDIANA 844 PM EST THU NOV 20 2008 .UPDATE... HAVE UPDATED FORECAST TO INCLUDE CASS COUNTY MICHIGAN IN WARNING. LATEST RADAR TRENDS SHOWED THIS AREA UNDER A STRONG BAND SINCE LATE AFTERNOON AND PHONE CALLS INDICATED 3 INCHES HAD FALLEN IN JUST A COUPLE HOURS. UPSTREAM REPORTS TO THE NORTH ALSO INDICATED CLOSE TO 6 INCHES. REMAINDER OF HEADLINES REMAIN UNCHANGED AT THIS TIME BUT SOME GROWING CONCERN FOR NORTHERN ELKHART COUNTY LATER TONIGHT. LATEST RUC13 PAINTS AND INTERESTING PICTURE FOR LAKE BAND EVOLUTION TONIGHT. SHORE PARALLEL SINGLE BAND BEGINNING TO GET MORE ORGANIZED PER REGIONAL RADAR MOSAIC AND IS CURRENTLY ALIGNING ITSELF RIGHT ALONG EASTERN LAKESHORE NORTH OF BENTON HARBOR. WATER VAPOR SHOWING SHORT WAVE PASSING THROUGH THE REGION AND THIS IS DISRUPTING BANDS SLIGHTLY OVER OUR AREA BUT VEERING WINDS BEHIND IT IS HELPING SET UP THE SINGLE BAND. WE ARE ALSO BEGINNING TO SEE A STRONG STREAMER CONNECTION TO LAKE SUPERIOR WHICH SHOULD HELP FUEL THIS BAND OVERNIGHT. RUC13 925MB OMEGA HAS THIS HANDLED WELL WITH ITS DEPICTION OF A WAVE OF STRONG LIFT MOVING SOUTH OVERNIGHT FROM SUPERIOR AND PHASING WITH CURRENT DEVELOPING BAND. THUS GOING FORECAST ON TRACK FOR NOW AND MORE INTENSE BANDS EXPECTED AFTER MIDNIGHT AND INTO FRIDAY MORNING. OF SOME CONCERN IS WHERE THE HEAVIEST SNOW WILL FALL. MODEL OMEGA FIELDS HAVE BEEN DISPLACED A BIT TOO FAR WEST...WHICH WE HAVE NOTED AS A BIAS AT TIMES IN THE MODELS. HOWEVER THIS WAS NOT THE CASE EARLIER THIS WEEK. RADAR TRENDS SUGGEST THAT AT LEAST THROUGH THE NEXT SEVERAL HOURS...EASTERN BERRIEN AND WESTERN CASS COUNTIES IN MICHIGAN ALONG WITH ST. JOSEPH AND WESTERN ELKHART COUNTIES IN INDIANA WILL BE IN THE BULLSEYE OF THIS DEVELOPING BAND. THEREFORE CASS WAS UPGRADED TO THE WARNING AND WE ARE MONITORING TRENDS FOR POSSIBLY UPGRADING ELKHART. SECONDARY BAND COMING ONSHORE INTO SOUTHERN BERRIEN AND LAPORTE COUNTIES HAS BEEN RATHER EFFICIENT WITH ESTIMATED REPORTS OF 3 TO 4 INCHES. OUTSIDE OF HEADLINE AREAS...BANDS HAVE BEEN VERY EFFICIENT AND PRODUCING NARROW AND BRIEF BANDS OF INTENSE SNOWFALL. KFWA REPORTED HEAVY SNOW FOR A FEW MINUTES AND THIS BAND HAS INTENSIFIED LAST HALF HOUR. ADDED SCATTERED SNOW SHOWERS TO EASTERN AREAS WITH UP TO AN INCH POSSIBLE GIVEN THE HEAVY BUT BRIEF NATURE. FURTHER UPDATES MAY BE NEEDED AS THIS BAND BECOMES MORE NORTH SOUTH ORIENTED. && .AVIATION... LAKE EFFECT SNOW SHOWERS EXPECTED TO BE PROBLEMATIC AT KSBN OVERNIGHT WITH LESS IMPACT AT KFWA. NORTHWEST FLOW AT ISSUANCE TIME EXPECTED TO VEER MORE NORTHERLY. THIS WILL ALLOW CURRENT BANDS NORTH OF KSBN TO SLIDE SOUTHWARD AND IMPACT KSBN THROUGH THE NIGHT. KFWA WILL BE ON FAR EASTERN FRINGE OF THIS BAND WITH SOME RESTRICTION POSSIBLE FOR A FEW HOURS THIS EVENING BEFORE MORE NORTHERLY FLOW PUSHES BAND WEST OF KFWA AND LEAVES BEHIND VFR CIGS. OF A LITTLE CONCERN IS 23Z SURFACE OBS SHOWING A MORE NORTHWEST WIND THAN MODEL INDICATIONS. TRANSITION TO NORTHERLY FLOW MAY BE DELAYED BUT WILL BE MONITORED. OTHER CONCERN IS EXACT LOCATION OF BAND THROUGH THE NIGHT. CURRENT INDICATIONS ARE THAT IT COULD BE PROLONGED OVER KSBN SO CONTINUED WITH 1SM RESTRICTION AT KSBN AND WILL AMEND LOWER AS NEEDED BASED ON OBSERVATIONS. IMPROVEMENT EXPECTED ON FRIDAY AS FLOW BECOMES WESTERLY AND WARMER AIR BEGINS TO LOWER INVERSION AND BEGIN TO BREAK DOWN LAKE EFFECT. && .SHORT TERM...(TONIGHT THROUGH FRIDAY NIGHT)... LAKE EFFECT SNOW EVENT IN ITS INFANCY ONGOING ACROSS NW INDIANA AND SW MICHIGAN THIS AFTERNOON. MAINLY DISORGANIZED MULTIPLE BANDS WITH LOW QPF AND LITE SNOW AMOUNTS THUS FAR. NEVERTHELESS...SETUP IS UNDERWAY AND COMPARISON OF NAM BUFR SOUNDING WITH ASCENT SOUNDING FROM 16Z OUT OF KSBN MATCHES UP WELL. H85 TEMPS AROUND -10C PRODUCING LOW END DELTA-T OF 16 DEG WITH BASICALLY UNIDIRECTIONAL WINDS BETWEEN 310-330 DEG AT AROUND 20KT. SOUNDING ALSO CONFIRMS SIGNIFICANT COOLING FURTHER ALOFT AT H7 UNDERWAY WITH TEMPS AHEAD OF 12Z MODEL PROGS HAVING FALLEN TO -20C BY 16Z. FOLLOWED NAM12 WITH FORECAST DETAILS WITH ITS GOOD HANDLE ON VERTICAL PROFILE AND CONSISTENCY WITH 12Z RUN. WINDS VEER A LITTLE MORE NORTHERLY AS INSTABILITY INCREASES THIS EVENING AND PEAKS OVERNIGHT WITH MORE COOLING ALOFT INCREASING DELTA T VALUES TO 20C WITH HIGH EQL PEAKING NEAR 15KFT AND EXCELLENT LAKE INDUCED CAPE THROUGHOUT THE GROWTH ZONE. NAM12/RUC DEPICTION OF LAKE EFFECT PLUME CONSISTENT WITH PVS RUNS AND WITH INHERITED FORECAST WITH ALL SIGNS CONTINUING TO POINT TO THE FORMATION OF A DOMINANT BAND OVERNIGHT WITH HEAVIEST IMPACT ALONG NE LAPORTE...BERRIEN...AND ST JOSEPH COUNTIES WITH ADVISORY FURTHER SOUTH ALONG FCST BEST UVM INTO FULTON COUNTY. LAKE INDUCED CAPE BEGINS TO COLLAPSE AFTER 12Z AS WARMER AIR STARTS TO MOVE IN ALOFT HWVR EQL LEVELS REMAIN AOB LOW END OF GROWTH ZONE WITH SOME LAKE INDUCED CAPE THROUGH 21Z PER NAM BFR SOUNDINGS. HOWEVER FETCH IS SHARPLY CUT BEYOND 18Z AS LL WINDS BACK TO WNW. ACCUMULATING SNOW SLACKENS AS IT SHIFTS NORTH WITH BACKING WINDS AND COMES TO AND END ABRUPTLY BEYOND 18Z AS SETUP FALLS APART. WITH CONTINUED CLOUD COVER HIGHS FRIDAY PEAK ONLY NEAR 30. LOWS SATURDAY MORNING COULD BE PROBLEMATIC AS AREAS WITH FRESH SNOW COVER THAT CLEAR OUT BEFORE MORNING COULD COOL MORE THAN GUIDANCE WOULD INDICATE. SFC RIDGE TO THE SOUTH NOW LOOKS TO BE A BIT FURTHER AWAY AND WITH LIGHT GRADIENT WINDS A POSSIBILITY WILL RIDE GUIDANCE FOR LOW TEMPS PRIMARILY IN THE UPPER TEENS. && .LONG TERM...(SATURDAY THROUGH THURSDAY)... SURFACE HIGH PRESSURE CENTERED OVER THE TN VALLEY WILL BRING A QUIET START TO THE EXTENDED PERIOD. NW FLOW ALOFT WILL BRING WEAK UPPER LEVEL DISTURBANCE INTO THE REGION SATURDAY AFTERNOON. WITH SURFACE HIGH UNDERNEATH...LITTLE MOISTURE AND FORCING TO WORK WITH SO NOTHING MORE THAN AN INCREASE IN CLOUDS FOR NOW. SURFACE HIGH MOVES TO CAROLINA COAST SUNDAY AND NEXT SYSTEM TAKES SHAPE IN THE PLAINS SETTING UP BRISK SW FLOW FOR OUR AREA. FRONT APPROACHES SUNDAY NIGHT BRINGING NEXT CHANCE FOR PRECIP. DECENT AMOUNT OF WAA AHEAD OF THE FRONT WILL BRING PRECIP TYPE INTO QUESTION. DPROG/DT INDICATING GFS FAIRLY CONSISTENT PAST FEW RUNS WITH OUR AREA BEING CLOSE TO RAIN/SNOW THRESHOLD. BUFKIT SOUNDING ALSO SHOWING SHALLOW 1200FT SFC BASED WARM LAYER SO WILL CONTINUE WITH MIX OF RA/SN SUNDAY NIGHT...THEN ALL SNOW MONDAY AFTER FROPA. CYCLONIC NW FLOW IN THE WAKE OF THIS SYSTEM WILL BRING ANOTHER ROUND OF LES MONDAY AND TUESDAY. HIGH PRESSURE AGAIN SETTLES INTO TN VALLEY BY WEDNESDAY BRINGING DRY FCST THROUGH THANKSGIVING DAY. EXPECT TEMPS TO GENERALLY REMAIN AOB NORMAL THROUGH THE PERIOD. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...LAKE EFFECT SNOW WARNING UNTIL 1 PM EST /12 PM CST/ FRIDAY FOR INZ003-004. LAKE EFFECT SNOW ADVISORY UNTIL 1 PM EST /12 PM CST/ FRIDAY FOR INZ005-012-014>016. MI...LAKE EFFECT SNOW WARNING UNTIL 1 PM EST FRIDAY FOR MIZ077 AND MIZ078. OH...NONE. LM...GALE WARNING UNTIL 4 AM EST FRIDAY FOR LMZ043-046. && $$ UPDATE...LASHLEY SHORT TERM...LUDINGTON LONG TERM...LOGSDON AVIATION...LASHLEY in AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NORTHERN INDIANA 635 PM EST THU NOV 20 2008 .AVIATION... LAKE EFFECT SNOW SHOWERS EXPECTED TO BE PROBLEMATIC AT KSBN OVERNIGHT WITH LESS IMPACT AT KFWA. NORTHWEST FLOW AT ISSUANCE TIME EXPECTED TO VEER MORE NORTHERLY. THIS WILL ALLOW CURRENT BANDS NORTH OF KSBN TO SLIDE SOUTHWARD AND IMPACT KSBN THROUGH THE NIGHT. KFWA WILL BE ON FAR EASTERN FRINGE OF THIS BAND WITH SOME RESTRICTION POSSIBLE FOR A FEW HOURS THIS EVENING BEFORE MORE NORTHERLY FLOW PUSHES BAND WEST OF KFWA AND LEAVES BEHIND VFR CIGS. OF A LITTLE CONCERN IS 23Z SURFACE OBS SHOWING A MORE NORTHWEST WIND THAN MODEL INDICATIONS. TRANSITION TO NORTHERLY FLOW MAY BE DELAYED BUT WILL BE MONITORED. OTHER CONCERN IS EXACT LOCATION OF BAND THROUGH THE NIGHT. CURRENT INDICATIONS ARE THAT IT COULD BE PROLONGED OVER KSBN SO CONTINUED WITH 1SM RESTRICTION AT KSBN AND WILL AMEND LOWER AS NEEDED BASED ON OBSERVATIONS. IMPROVEMENT EXPECTED ON FRIDAY AS FLOW BECOMES WESTERLY AND WARMER AIR BEGINS TO LOWER INVERSION AND BEGIN TO BREAK DOWN LAKE EFFECT. && .SHORT TERM...(TONIGHT THROUGH FRIDAY NIGHT)... LAKE EFFECT SNOW EVENT IN ITS INFANCY ONGOING ACROSS NW INDIANA AND SW MICHIGAN THIS AFTERNOON. MAINLY DISORGANIZED MULTIPLE BANDS WITH LOW QPF AND LITE SNOW AMOUNTS THUS FAR. NEVERTHELESS...SETUP IS UNDERWAY AND COMPARISON OF NAM BUFR SOUNDING WITH ASCENT SOUNDING FROM 16Z OUT OF KSBN MATCHES UP WELL. H85 TEMPS AROUND -10C PRODUCING LOW END DELTA-T OF 16 DEG WITH BASICALLY UNIDIRECTIONAL WINDS BETWEEN 310-330 DEG AT AROUND 20KT. SOUNDING ALSO CONFIRMS SIGNIFICANT COOLING FURTHER ALOFT AT H7 UNDERWAY WITH TEMPS AHEAD OF 12Z MODEL PROGS HAVING FALLEN TO -20C BY 16Z. FOLLOWED NAM12 WITH FORECAST DETAILS WITH ITS GOOD HANDLE ON VERTICAL PROFILE AND CONSISTENCY WITH 12Z RUN. WINDS VEER A LITTLE MORE NORTHERLY AS INSTABILITY INCREASES THIS EVENING AND PEAKS OVERNIGHT WITH MORE COOLING ALOFT INCREASING DELTA T VALUES TO 20C WITH HIGH EQL PEAKING NEAR 15KFT AND EXCELLENT LAKE INDUCED CAPE THROUGHOUT THE GROWTH ZONE. NAM12/RUC DEPICTION OF LAKE EFFECT PLUME CONSISTENT WITH PVS RUNS AND WITH INHERITED FORECAST WITH ALL SIGNS CONTINUING TO POINT TO THE FORMATION OF A DOMINANT BAND OVERNIGHT WITH HEAVIEST IMPACT ALONG NE LAPORTE...BERRIEN...AND ST JOSEPH COUNTIES WITH ADVISORY FURTHER SOUTH ALONG FCST BEST UVM INTO FULTON COUNTY. LAKE INDUCED CAPE BEGINS TO COLLAPSE AFTER 12Z AS WARMER AIR STARTS TO MOVE IN ALOFT HWVR EQL LEVELS REMAIN AOB LOW END OF GROWTH ZONE WITH SOME LAKE INDUCED CAPE THROUGH 21Z PER NAM BFR SOUNDINGS. HOWEVER FETCH IS SHARPLY CUT BEYOND 18Z AS LL WINDS BACK TO WNW. ACCUMULATING SNOW SLACKENS AS IT SHIFTS NORTH WITH BACKING WINDS AND COMES TO AND END ABRUPTLY BEYOND 18Z AS SETUP FALLS APART. WITH CONTINUED CLOUD COVER HIGHS FRIDAY PEAK ONLY NEAR 30. LOWS SATURDAY MORNING COULD BE PROBLEMATIC AS AREAS WITH FRESH SNOW COVER THAT CLEAR OUT BEFORE MORNING COULD COOL MORE THAN GUIDANCE WOULD INDICATE. SFC RIDGE TO THE SOUTH NOW LOOKS TO BE A BIT FURTHER AWAY AND WITH LIGHT GRADIENT WINDS A POSSIBILITY WILL RIDE GUIDANCE FOR LOW TEMPS PRIMARILY IN THE UPPER TEENS. && .LONG TERM...(SATURDAY THROUGH THURSDAY)... SURFACE HIGH PRESSURE CENTERED OVER THE TN VALLEY WILL BRING A QUIET START TO THE EXTENDED PERIOD. NW FLOW ALOFT WILL BRING WEAK UPPER LEVEL DISTURBANCE INTO THE REGION SATURDAY AFTERNOON. WITH SURFACE HIGH UNDERNEATH...LITTLE MOISTURE AND FORCING TO WORK WITH SO NOTHING MORE THAN AN INCREASE IN CLOUDS FOR NOW. SURFACE HIGH MOVES TO CAROLINA COAST SUNDAY AND NEXT SYSTEM TAKES SHAPE IN THE PLAINS SETTING UP BRISK SW FLOW FOR OUR AREA. FRONT APPROACHES SUNDAY NIGHT BRINGING NEXT CHANCE FOR PRECIP. DECENT AMOUNT OF WAA AHEAD OF THE FRONT WILL BRING PRECIP TYPE INTO QUESTION. DPROG/DT INDICATING GFS FAIRLY CONSISTENT PAST FEW RUNS WITH OUR AREA BEING CLOSE TO RAIN/SNOW THRESHOLD. BUFKIT SOUNDING ALSO SHOWING SHALLOW 1200FT SFC BASED WARM LAYER SO WILL CONTINUE WITH MIX OF RA/SN SUNDAY NIGHT...THEN ALL SNOW MONDAY AFTER FROPA. CYCLONIC NW FLOW IN THE WAKE OF THIS SYSTEM WILL BRING ANOTHER ROUND OF LES MONDAY AND TUESDAY. HIGH PRESSURE AGAIN SETTLES INTO TN VALLEY BY WEDNESDAY BRINGING DRY FCST THROUGH THANKSGIVING DAY. EXPECT TEMPS TO GENERALLY REMAIN AOB NORMAL THROUGH THE PERIOD. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...LAKE EFFECT SNOW WARNING UNTIL 1 PM EST /12 PM CST/ FRIDAY FOR INZ003-004. LAKE EFFECT SNOW ADVISORY UNTIL 1 PM EST /12 PM CST/ FRIDAY FOR INZ005-012-014>016. MI...LAKE EFFECT SNOW WARNING UNTIL 1 PM EST FRIDAY FOR MIZ077. LAKE EFFECT SNOW ADVISORY UNTIL 1 PM EST FRIDAY FOR MIZ078. OH...NONE. LM...GALE WARNING UNTIL 4 AM EST FRIDAY FOR LMZ043-046. && $$ SHORT TERM...LUDINGTON LONG TERM...LOGSDON AVIATION...LASHLEY in AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NORTHERN INDIANA 358 PM EST THU NOV 20 2008 .SHORT TERM...(TONIGHT THROUGH FRIDAY NIGHT)... LAKE EFFECT SNOW EVENT IN ITS INFANCY ONGOING ACROSS NW INDIANA AND SW MICHIGAN THIS AFTERNOON. MAINLY DISORGANIZED MULTIPLE BANDS WITH LOW QPF AND LITE SNOW AMOUNTS THUS FAR. NEVERTHELESS...SETUP IS UNDERWAY AND COMPARISON OF NAM BUFR SOUNDING WITH ASCENT SOUNDING FROM 16Z OUT OF KSBN MATCHES UP WELL. H85 TEMPS AROUND -10C PRODUCING LOW END DELTA-T OF 16 DEG WITH BASICALLY UNIDIRECTIONAL WINDS BETWEEN 310-330 DEG AT AROUND 20KT. SOUNDING ALSO CONFIRMS SIGNIFICANT COOLING FURTHER ALOFT AT H7 UNDERWAY WITH TEMPS AHEAD OF 12Z MODEL PROGS HAVING FALLEN TO -20C BY 16Z. FOLLOWED NAM12 WITH FORECAST DETAILS WITH ITS GOOD HANDLE ON VERTICAL PROFILE AND CONSISTENCY WITH 12Z RUN. WINDS VEER A LITTLE MORE NORTHERLY AS INSTABILITY INCREASES THIS EVENING AND PEAKS OVERNIGHT WITH MORE COOLING ALOFT INCREASING DELTA T VALUES TO 20C WITH HIGH EQL PEAKING NEAR 15KFT AND EXCELLENT LAKE INDUCED CAPE THROUGHOUT THE GROWTH ZONE. NAM12/RUC DEPICTION OF LAKE EFFECT PLUME CONSISTENT WITH PVS RUNS AND WITH INHERITED FORECAST WITH ALL SIGNS CONTINUING TO POINT TO THE FORMATION OF A DOMINANT BAND OVERNIGHT WITH HEAVIEST IMPACT ALONG NE LAPORTE...BERRIEN...AND ST JOSEPH COUNTIES WITH ADVISORY FURTHER SOUTH ALONG FCST BEST UVM INTO FULTON COUNTY. LAKE INDUCED CAPE BEGINS TO COLLAPSE AFTER 12Z AS WARMER AIR STARTS TO MOVE IN ALOFT HWVR EQL LEVELS REMAIN AOB LOW END OF GROWTH ZONE WITH SOME LAKE INDUCED CAPE THROUGH 21Z PER NAM BFR SOUNDINGS. HOWEVER FETCH IS SHARPLY CUT BEYOND 18Z AS LL WINDS BACK TO WNW. ACCUMULATING SNOW SLACKENS AS IT SHIFTS NORTH WITH BACKING WINDS AND COMES TO AND END ABRUPTLY BEYOND 18Z AS SETUP FALLS APART. WITH CONTINUED CLOUD COVER HIGHS FRIDAY PEAK ONLY NEAR 30. LOWS SATURDAY MORNING COULD BE PROBLEMATIC AS AREAS WITH FRESH SNOW COVER THAT CLEAR OUT BEFORE MORNING COULD COOL MORE THAN GUIDANCE WOULD INDICATE. SFC RIDGE TO THE SOUTH NOW LOOKS TO BE A BIT FURTHER AWAY AND WITH LIGHT GRADIENT WINDS A POSSIBILITY WILL RIDE GUIDANCE FOR LOW TEMPS PRIMARILY IN THE UPPER TEENS. && .LONG TERM...(SATURDAY THROUGH THURSDAY)... SURFACE HIGH PRESSURE CENTERED OVER THE TN VALLEY WILL BRING A QUIET START TO THE EXTENDED PERIOD. NW FLOW ALOFT WILL BRING WEAK UPPER LEVEL DISTURBANCE INTO THE REGION SATURDAY AFTERNOON. WITH SURFACE HIGH UNDERNEATH...LITTLE MOISTURE AND FORCING TO WORK WITH SO NOTHING MORE THAN AN INCREASE IN CLOUDS FOR NOW. SURFACE HIGH MOVES TO CAROLINA COAST SUNDAY AND NEXT SYSTEM TAKES SHAPE IN THE PLAINS SETTING UP BRISK SW FLOW FOR OUR AREA. FRONT APPROACHES SUNDAY NIGHT BRINGING NEXT CHANCE FOR PRECIP. DECENT AMOUNT OF WAA AHEAD OF THE FRONT WILL BRING PRECIP TYPE INTO QUESTION. DPROG/DT INDICATING GFS FAIRLY CONSISENT PAST FEW RUNS WITH OUR AREA BEING CLOSE TO RAIN/SNOW THRESHOLD. BUFKIT SOUNDING ALSO SHOWING SHALLOW 1200FT SFC BASED WARM LAYER SO WILL CONTINUE WITH MIX OF RA/SN SUNDAY NIGHT...THEN ALL SNOW MONDAY AFTER FROPA. CYCLONIC NW FLOW IN THE WAKE OF THIS SYSTEM WILL BRING ANOTHER ROUND OF LES MONDAY AND TUESDAY. HIGH PRESSURE AGAIN SETTLES INTO TN VALLEY BY WEDNESDAY BRINGING DRY FCST THROUGH THANKSGIVING DAY. EXPECT TEMPS TO GENERALLY REMAIN AOB NORMAL THROUGH THE PERIOD. && .AVIATION... DIFFICULT TAF FORECAST WITH MULTIPLE LAKE EFFECT SNOW BANDS THIS AFTN...TRANSITIONING INTO A SHORE PARALLEL SINGLE BAND TONIGHT. AT FWA...EXPECT MVFR/LOW END VFR CONDITIONS WITH NUMEROUS SHSN THROUGH 03/04Z THIS EVENING. PARTIAL CLEARING/VFR CONDITIONS CAN BE EXPECTED BY MIDNIGHT AS DRY LL AIR SETTLES IN BEHIND A DEPARTING SECONDARY TROUGH...ALONG WITH SUBSIDENCE ON EAST SIDE OF A SINGLE BAND THAT SHOULD SET UP WELL WEST OF THE TERMINAL. AT SBN...SIGNIFICANT VIS/CIG RESTRICTIONS ARE EXPECTED AS LAKE EFFECT SHSN ACTIVITY INCREASES IN COVERAGE/INTENSITY THIS AFTN...AS APPROACHING SECONDARY WAVE ALLOWS FOR INCRG SYNOPTIC MOISTURE AND INVERSION HEIGHTS FOR DEEPER CONVECTIVE CELLS. INTENSE SINGLE BAND LIKELY TO SET UP TONIGHT OVER/NEAR SBN BTW 00Z AND 03Z. EXACT LOCATION OF NARROW BAND OF HVY SN/LIFR CONDITIONS STILL SOMEWHAT UNCERTAIN...ALTHOUGH PROGGED 925-850MB FLOW IS FAVORABLE FOR SBN TO END UP WITHIN THIS BAND FOR SEVERAL HOURS. WILL CONTINUE WITH LOW IFR FCST AT SBN TONIGHT AND WILL AMEND AS NEEDED. A GRADUAL IMPROVEMENT IS EXPECTED AT SBN FRIDAY MORNING PER SUBSIDENCE BEHIND SHRTWV TROUGH AND BACKING LL FLOW. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...LAKE EFFECT SNOW WARNING UNTIL 1 PM EST /12 PM CST/ FRIDAY FOR INZ003-004. LAKE EFFECT SNOW ADVISORY UNTIL 1 PM EST /12 PM CST/ FRIDAY FOR INZ005-012-014>016. MI...LAKE EFFECT SNOW WARNING UNTIL 1 PM EST FRIDAY FOR MIZ077. LAKE EFFECT SNOW ADVISORY UNTIL 1 PM EST FRIDAY FOR MIZ078. OH...NONE. LM...GALE WARNING UNTIL 4 AM EST FRIDAY FOR LMZ043-046. && $$ SHORT TERM...LUDINGTON LONG TERM...LOGSDON AVIATION...STEINWEDEL in AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NORTHERN INDIANA 635 AM EST WED NOV 19 2008 .AVIATION... ALTO/STRATO CU DECK OVER MI/WI/IN/IL HAS BEEN EXPANDING THIS MORNING IN AREA OF STRONG LOW LEVEL WAA/ISENT LIFT. NAM/GFS RH FIELDS NOT HANDLING THESE CLOUDS WELL. BASED ON RUC FCST SOUNDINGS AND EWD EXTRAPOLATION OF BACK EDGE...EXPECT THIS DECK WILL REMAIN OVER NRN INDIANA MUCH OF THE DAY WITH CIGS GRDLY LOWERING AS LOW LEVEL CYCLONIC FLOW OVER THE GRTLKS STRENGTHENS AS A LOW PRESSURE SYSTEM MOVES ESE ACROSS THE REGION TODAY. LOW LEVEL CAA SHOULD RESULT IN CIGS LOWERING TO MVFR BEHIND CDFNT TNGT WITH SOME LAKE EFFECT SNOW SHOWERS BEGINNING AT SBN. LOW INVERSION HEIGHTS SHOULD LIMIT INTENSITY OF THIS PRECIP OVERNIGHT SO KEPT VSBYS VFR. && .PREV DISCUSSION... /ISSUED 429 AM EST WED NOV 19 2008/ SHORT TERM... LOW PRESSURE SYSTEM OVER NRN PLAINS WILL MOVE SE ACROSS THE GRTLKS TODAY/TNGT. SYNOPTIC SCALE MOISTURE MEAGER ALONG/AHEAD OF THIS SYSTEM... SO WAA PRECIP AHEAD OF THE LOW WILL STAY NORTH OF THE CWA...HWVR... SUFFICIENT MOISTURE IS AVAILABLE FOR CONSIDERABLE MID/HIGH CLOUDS UPSTREAM WHICH SHOULD CONT TO OVERSPREAD THE AREA TODAY. BASED ON LIMITED SUNSHINE AND RATHER COOL START ESPECIALLY OVER ERN PORTIONS OF CWA...CONTD WITH PREVIOUS FCST FOR HIGHS WHICH ARE GENERALLY AT OR SLIGHTLY BLO COOLEST MOS FOR TODAY. AS FRONT MOVES THROUGH THE AREA TONIGHT SOME ADDITIONAL MOISTURE OFF LAKE MICHIGAN MAY ALLOW FOR SCT SNOW SHOWERS TO DVLP... SO LEFT GOING POPS IN TACT. STRONG CAA BEHIND THE FRONT WILL ALLOW LAKE EFFECT SNOW SHOWERS TO DEVELOP THU MORNING. AS USUAL IN THESE SITUATIONS NAM IS CONSIDERABLY MORE MOIST IN LOW LEVELS THAN GFS. GIVEN THE BETTER RESOLUTION OF THE NAM... EXPECT IT TO OUTPERFORM THE GFS FOR THIS EVENT AND IT DOES APPEAR TO BE HANDLING THE LAKE AGGREGATE TROUGHING BETTER DURING THIS PERIOD. THUS HAVE LEANED TOWARD IT`S SOLUTION WHICH CONTS TO SUGGEST POTENTIAL FOR HEAVY LAKE EFFECT SNOW SHOWERS AS LAKE INDUCED INSTABILITY INCREASES TO >1000J/KG WITH WITH EQUILIBRIUM LEVELS >15KFT. MEAN LOW LEVEL WINDS ARE EXPECTED TO BE 320-340DEG THU-THU NGT AND WITH SUPPORT OF 925MB UVM FIELDS AND NAM QPF SUGGESTS POTENTIAL FOR HEAVY SNOW OVER BERRIEN/CASS IN SW MICHIGAN AND ST. JOE...NW ELKHART...AND NE LAPORTE COUNTIES IN NRN INDIANA...THUS ISSUED A LAKE EFFECT SNOW WATCH FOR THIS AREA BEGINNING THU MORNING AND CONTG INTO THE LONG TERM PD. LONG TERM... FRIDAY THROUGH TUESDAY...ANOTHER LAKE EVENT SNOW EVENT SHOULD BE ONGOING AT THE START OF THE PERIOD. THE GFS AND NAM/WRF INDICATE TEMPS WILL BE A LITTLE COLDER THAN THE LAST EVENT WITH DELTA T VALUES REACHING 20 TO 25. IT LOOKS LIKE THE KEY FACTOR IN LAKE EFFECT SNOW POTENTIAL FRIDAY WILL BE THE FETCH OVER THE LAKE. EXPECT 300 TO 310 DEGREES SO FETCH WILL BE SUFFICIENT FOR LAKE EFFECT SNOW BUT NOT OPTIMAL. VERY DRY AIR WILL BE SPREADING OVER THE LAKE FROM WISCONSIN WITH LITTLE IF ANY PRECONDITIONING...SO THESE SHOULD LIMIT HIGH END SNOW AMOUNTS. ALSO...WINDS WILL START BACKING DURING THE DAY IN THE LOWER LEVELS WITH THE APPROACH OF THE NEXT SYSTEM...SO ACTIVITY SHOULD BE WEAKENING ESPECIALLY DURING THE AFTERNOON. GIVEN THE ABOVE...WENT WITH BASICALLY 3 TO 5 INCHES OF SNOW FROM BERRIEN COUNTY SOUTHEAST INTO CASS AND ELKHART FRIDAY. OTHER THAN FLURRIES FRIDAY EVENING...KEPT THE FORECAST DRY THROUGH NOON SUNDAY. PRECIPITATION CHANCES THROUGH SUNDAY NIGHT DO NOT LOOK IMPRESSIVE GIVEN MORE OF A DRY SLOT TRACK OVER THE FORECAST AREA AND LIMITED MOISTURE RETURN. THE GFS AND ECMWF HAVE FINALLY COME INTO BETTER AGREEMENT WITH EACH OTHER IN THE HANDLING OF THIS SYSTEM. HOWEVER FAVOR THE COLDER GFS GIVEN RECENT TRENDS AND THE LATEST ANALOG SIGNALS SHOWING A VERY LARGE NEGATIVE HEIGHT ANOMALY OVER THE GREAT LAKES REGION. AS A RESULT...KEPT A CHANCE FOR MAINLY LAKE EFFECT SNOW MONDAY INTO TUESDAY. PREV DISCUSSION... /ISSUED 1235 AM EST WED NOV 19 2008/ AVIATION... LOW PRESSURE OVER ERN ND WILL MOVE ESE ACROSS NRN MICHIGAN THIS EVENING WITH TRAILING CDFNT CROSSING NRN INDIANA WITH FROPA AT SBN AROUND 02Z AND FWA 05Z. AS FRONT APPROACHES TODAY...WARM/MOIST ADVECTION SHOULD RESULT IN CIRRUS GRADUALLY LOWERING TO VFR CIGS WITH MVFR MOVG IN BEHIND THE FRONT. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...LAKE EFFECT SNOW WATCH FROM THURSDAY MORNING THROUGH FRIDAY EVENING FOR INZ003>005. MI...LAKE EFFECT SNOW WATCH FROM THURSDAY MORNING THROUGH FRIDAY EVENING FOR MIZ077-078. OH...NONE. LM...GALE WARNING FROM 7 PM THIS EVENING TO 7 PM EST THURSDAY FOR LMZ043-046. && $$ SHORT TERM/AVIATION...TAYLOR LONG TERM...SKIPPER in AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE QUAD CITIES IA IL 225 PM CDT THU NOV 20 2008 .SYNOPSIS... MID LEVEL SHORTWAVE DROPPING SOUTH ACROSS REGION ATTIM ACCOMPANIED BY CONSIDERABLE CLOUDINESS AND FEW FLURRIES. CLOUDS MORE CELLULAR ON BACK EDGE OF MAIN STRATUS SHIELD DUE TO DESTABILIZATION WITH SOLAR INSOLATION/HEATING AND COLD AIR WITH SEVERAL ROLLS OF STRATOCU ORIENTED FROM NW TO SE PRODUCING FEW LIGHT SHSN WITH KDVN WSR-88D EVERY ONCE IN A WHILE PICKING UP 20-25 DBZ RETURNS WITHIN THESE BANDS. MEANWHILE... SUBSIDENCE IN THE WAKE OF MID LEVEL SHORTWAVE WAS PROVIDING FOR CLEARING SKIES IMMEDIATELY UPSTREAM ACROSS CENTRAL MN...NORTHERN AND WESTERN IA INTO PORTIONS OF SOUTHERN WI. WATER VAPOR SHOWS ANOTHER MID LEVEL SHORTWAVE DIVING S/SE TOWARD ARROWHEAD OF MN AT 18Z. THIS WAS ASSISTING CONSIDERABLE STRATOCU DEVELOPMENT NORTHERN MN INTO NORTHERN WI AND U.P. OF MI. LARGE... COLD 1048+ MB CANADIAN HIGH CENTERED OVER SOUTHERN MANITOBA AT 18Z PROVIDING A WINTER CHILL AS TEMPS RUNNING WELL BELOW NORMAL ACROSS PLAINS AND MIDWEST. SOME AREAS STILL IN SINGLE DIGITS AND TEENS EARLY THIS AFTN FROM ND INTO MN WITH SNOW COVER AND/OR CLOUDS. BRISK/BLUSTERY NORTHWEST WINDS GUSTING TO AROUND 30 MPH AT TIMES ADDING TO WINTER CHILL... WITH WIND CHILLS IN THE TEENS TO NEAR 20 DEGREES AT TIMES OVER CWA. ..M^2.. && .SHORT TERM...TONIGHT AND FRIDAY... TEMPS TO REMAIN WELL BELOW NORMAL DURING PERIOD AS LARGE CANADIAN HIGH SETTLES OVER REGION AND EVENTUALLY BEGINS TO PUSH EAST BY FRI AFTN. MAIN CHALLENGE IS WITH HOW COLD TO GO ON LOWS TONIGHT. MIN TEMP FCST ACTUALLY BECOMING A BIT MORE CHALLENGING THAN INITIALLY THOUGHT... MAINLY DUE TO CLOUD TRENDS AND WINDS. INITIAL CLEARING TO SWEEP ACROSS AREA BY EARLY EVE... BUT WATCHING CLOUDS UPSTREAM OVER PORTIONS OF MN/WI AHEAD OF MID LEVEL IMPULSE DROPPING SOUTH THROUGH ARROWHEAD OF MN ATTIM. EARLY THINKING WAS INCOMING SUBSIDENCE AND LARGELY CELLULAR NATURE OF CLOUDS WOULD RESULT IN THINNING AS THEY ADVANCE S/SE TNGT...BUT RECENT VISIBLE SATL SHOWS CLOUDS SPREADING MORE INTO STRATUS WHICH HAS BETTER CHC OF HOLDING TOGETHER AND PROPAGATING ACROSS PORTIONS OF THE AREA TNGT. THIS IS DEPICTED WITH LATEST RUC AND 18Z NAM LOW LEVEL RH PROGS. WILL TAKE LATE LAST MINUTE LOOK TO DECIDE ON HOW TO HANDLE CLOUDS. ANY CLOUDS CERTAINLY WOULD BE WELCOMED ... ACTING AS BLANKET TO HOLD IN WHAT LITTLE HEATING TODAY. ALSO... WINDS LOOK TO BE SLOW TO DROP-OFF WITH GRADIENT KEEPING SOME GUSTS AROUND THIS EVE. THE COMBINATION OF ANY CLOUDS AND WINDS WOULD SERVE TO HELP AND PREVENT TEMPS FROM REALLY PLUMMETING. ACTUALLY SETUP LOOKS VERY FAVORABLE FOR BIG TEMP DROP TOWARD DAYBREAK AS SUGGESTIONS OF CLEARING BY 12Z AT THE SAME TIME WINDS DECOUPLING WITH RIDGE NEARING. BANKING ON THIS TO KEEP MINS FAIRLY CLOSE TO PREVIOUS FCST AND NEAR COLD SIDE OF GUIDANCE. FAIRLY SIMILAR SETUP TO TUE MORNING WITH STRENGTH/LOCATION OF HIGH WHICH YIELDED LOWS MAINLY IN RANGE OF 11-18 DEGS... WITH FEW URBAN AREAS AROUND 20 DEGS WITH HEAT ISLAND. SFC HIGH PROGGED TO BE A BIT STRONGER... WHICH WOULD SUPPORT TEMPS A LITTLE COLDER WITH POTENTIAL FOR SINGLE DIGITS NORTH/WEST. SFC RIDGE AXIS TO PASS ACROSS AREA DURING DAY ON FRI WITH WINDS BACKING TO S/SW IN THE AFTN... AND SOME WARMING ALOFT... BUT LIMITED MIXING TO KEEP US FROM REALIZING MUCH OF THIS WARMING AND STAYED NEAR COLDER SIDE OF GUIDANCE FOR MAXES... ESPECIALLY GIVEN VERY COLD START. ..M^2.. .LONG TERM...FRIDAY NIGHT THROUGH NEXT THURSDAY... FRIDAY NIGHT AND SATURDAY MORNING STAND TO SEE A CHANCE FOR ACCUMULATING LIGHT SNOW...DUE TO RESPECTABLE FORCING AT MID AND UPPER LEVELS AS A SHORT WAVE TROF MOVES SOUTHEAST THROUGH IOWA AND DAMPENS WITHIN THE OVER ALL FLOW PATTERN. THIS WOULD NORMALLY BE ENOUGH TO CREATE WIDESPREAD LIGHT SNOW IN THIS COLD AIRMASS...HOWEVER...MOISTURE IS VERY LIMITED...ESPECIALLY BELOW THE FORCING. THUS...SIGNIFICANT EVAPORATION IS EXPECTED...WHICH MAY CAUSE THE SNOW BE LIGHT ENOUGH TO NOT ACCUMULATE. STILL WITH THE FORCING IN PLACE...OUR CHANCE POPS SEEM ON TARGET...WITH THE BEST THREAT OF LIGHT ACCUMULATION NORTHEAST OF WASHINGTON...TO THE MUSCATINE. AMOUNTS SHOULD BE A DUSTING TO A HALF INCH. TEMPERATURES FRIDAY NIGHT WILL LIKELY BOTTOM OUT AROUND MIDNIGHT...WITH STEADY TEMPS OR SLIGHT RISES AFTERWORDS AS CLOUDS BECOME OPAQUE FROM WEST TO EAST. THESE SAME CLOUDS SHOULD HOLD DOWN SATURDAYS HIGHS FROM THERE POTENTIAL RANGE IN THE MID TO UPPER 40S...WITH ONLY HIGHS OF MID 30S NORTHEAST TO MID 40S SOUTHWEST EXPECTED. SATURDAY NIGHT THROUGH SUNDAY A FAST MOVING SYSTEM SHOULD PROVIDE CONTINUED WARM ADVECTION...RESULTING IN ONE MILD DAY NEAR NORMAL SUNDAY. HOWEVER...WITH CLOUDS AROUND AND BREEZY CONDITIONS...IT SHOULD NOT FEEL OVERLY NICE THIS WEEKEND. SUNDAY AFTERNOON THROUGH MONDAY NIGHT... LIMITED MOISTURE MAY BE WRUNG OUT OVER THE AREA THROUGH LIGHT SNOW SHOWERS OR FLURRIES. COLD TEMPS ARE AGAIN FORECAST FOR MONDAY AND TUESDAY AS THE NEXT CANADIAN COLD DUMP OCCURS IN THE WAKE OF THE SUNDAY LOW PASSAGE. IN THE EXTENDED...THE ECMWF SOLUTION HAS BEEN PREFERRED BY HPC THE PAST WEEK...AND IT WILL BE FAVORED AGAIN TODAY. HOWEVER...THERE IS GREAT UNCERTAINTY BEYOND TUESDAY...WITH THE OVER ALL SYNOPTIC FLOW FORECAST CONTINUITY POOR...EVEN WITHIN THE ECMWF RUNS. IN GENERAL...MODERATION TO NEAR NORMAL IS FORECAST. ..ERVIN.. && .AVIATION... SUBSIDENCE BEHIND DEPARTING MID LEVEL SHORTWAVE WILL BRING ABOUT CLEARING LATE AFTN INTO EARLY THIS EVE. HOWEVER...ANOTHER SHORTWAVE DIVING SOUTH THROUGH THE ARROWHEAD OF MN MAY BRING SOME ADDITIONAL LOW CLOUDS TO TERMINALS THIS EVE INTO OVERNIGHT FROM NORTH TO SOUTH... WITH CIGS MAINLY VFR THOUGH CANT RULE OUT PERIOD OF MVFR WITH SCT FLURRIES. GUSTY NORTHWEST WINDS TO SLOWLY SUBSIDE TONIGHT AS SFC RIDGE BUILDS INTO THE AREA. WINDS TO BACK TO WEST THEN SOUTHWEST AT OR JUST BEYOND 18Z FRI WITH MAINLY VFR CONDITIONS PREVAILING AS THE SFC HIGH SHIFTS ACROSS THE AREA. ..M^2.. && .DVN WATCHES/WARNINGS/ADVISORIES... IA...NONE. IL...NONE. MO...NONE. && $$ M^2/ERVIN ia AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE DES MOINES IA 1130 AM CST WED NOV 19 2008 ...UPDATED FOR FORECAST AND AVIATION DISCUSSION... .UPDATE... LOW LEVEL STRATUS DECK HOLDING TOGETHER...AND SEEPING SOUTHWARD INTO THE NORTHERN CWA OVER THE PAST FEW HOURS. NAM/RUC LOW LEVEL RH FIELDS SEEM TO HAVE A GOOD HANDLE ON PLACEMENT/TIMING AND THUS HAVE STRATUS DECK MAKING IT TO CENTRAL CWA BY LATE THIS AFTERNOON/EARLY EVENING. MODELS INDICATE STRATUS DECK EXPANDING OVERNIGHT...SO WILL HAVE TO MAKE SOME ADJUSTMENTS FOR THIS TIME PERIOD AS WELL. WITH THE LOW CLOUDS MOVING SOUTHWARD AND STRONG CAA EXPECT STEADY TO FALLING TEMPERATURES BEHIND COLD FRONTAL BOUNDARY ACROSS THE NORTHERN THIRD OF THE CWA...SO MADE APPROPRIATE ADJUSTMENTS TO THE TEMP FIELD AS WELL. .PREVIOUS DISCUSSION... .SHORT TERM.../TODAY THROUGH FRI NIGHT/ SURFACE LOW SWINGING ACROSS NORTHERN MN AND OVER LAKE SUPERIOR WILL BRING A COLD FRONT FROM NW TO SE ACROSS IOWA TODAY. THE FRONT WILL CROSS MOST OF OUR CWA BY NOON AND THE FAR SOUTHEAST IN EARLY AFTERNOON. WITH NNW WIND SURGE AND SOME LOW CLOUDS BEHIND FROPA...AS WELL AS SLIGHTLY DELAYED CAA...BIGGEST FORECAST DIFFICULTY IS PROGGING MAX TEMPS. OBVIOUSLY WILL BE COLDEST IN THE NORTH WHERE TEMPS ARE CURRENTLY LOWEST AND LEAST HEATING WILL TAKE PLACE DUE TO EARLIER FROPA. NO PRECIP EXPECTED WITH THE FRONT AS DRY AIR IS FIRMLY IN PLACE. OUTSIDE OF POTENTIAL FOR SOME FLURRIES/LIGHT SNOW SHOWERS IN RELATIVELY STEEP LOW LEVEL LAPSE RATES AND HIGHER LOW LEVEL RH THU...MAIN CONCERN WILL BE TEMP TRENDS TONIGHT THROUGH FRI. VORT LOBE SWINGS THROUGH LATE THU AS STRONG HIGH PRESSURE BECOMES ENTRENCHED IN THE MO RIVER VALLEY. AIRMASS REMAINS MIXED INTO THURSDAY AFTER CFP TONIGHT RESULTING IN RELATIVELY HIGH CONFIDENCE MINS AND MAXES. NAM/GFS SOUNDINGS IN GOOD AGREEMENT. THIS RESULTS IN GOING ABOVE GUIDANCE TONIGHT AND NEAR COMPROMISE THU. MIXING DOES NOT REALLY SUBSIDE UNTIL FRI SO HAVE GONE ABOVE GUIDANCE THU NIGHT WITH MIXING SEEMING TO KEEP TEMPS UP AND RADIATIONAL COOLING DOWN. LITTLE DECOUPLING NOTED THU NIGHT EITHER SO LOWS REMAIN ABOVE EVEN THE WARMEST GUIDANCE OUTSIDE OF KEST AND NISHNABOTNA VALLEY AREAS CLOSER TO RIDGE. MUCH LIKE PROGGED YESTERDAY...SHORT WAVE EJECTS OUT OF GULF AK LOW LATER TODAY REACHING MO VALLEY LATE FRI. 00Z GFS/ECMWF SOLUTIONS HAVE APPARENTLY CONVERGED ON A SOLUTION WITH THE GFS LESS AGGRESSIVE THAN PREVIOUS RUNS AND THE ECMWF MORE SO. NAM IS AN OUTLIER TO THE SOUTH AND WEST AND WILL NOT BE FOLLOWED. BUCKING GFS/ECMWF AGREEMENT IN FAVOR OF THE NAM IN LATER PERIODS IS RARELY THE WAY TO GO. THIS FAVORED SCENARIO RESULTS IN FAIRLY DEEP LAYER OF COINCIDENT KINEMATIC AND THERMODYNAMIC FORCING WITH NOTED FN RESPONSE. GFS COBB DATA DEPICTS TYPICAL 13:1 RATIOS WITH THE EVENT AND COULD RESULT IN 1-2 INCHES OVER NRN AND POSSIBLY INTO CENTRAL IA SO HAVE BOOSTED POPS WELL INTO CHANCE CATEGORY...ESPECIALLY NWRN SECTIONS BEFORE FORCING BEGINS TO WEAKEN AS SYSTEM HEADS SE. ALTHOUGH TEMPING...DID NOT WANT TO GO WITH LIKELY WORDING QUITE YET. THAT WOULD BE A BIG CHANGE FROM OUR CURRENT FORECAST...AND GFS MOS AS WELL AS SREF/GEFS PRECIP PROBS HAVE YET TO RESPOND TOO MUCH AND ONLY SUGGEST LOW END CHANCES FOR NOW. ALTHOUGH TRANSIENT NATURE OF THE SYSTEM SHOULD KEEP THINGS FROM GETTING OUT OF HAND...DECENT MOISTURE TRANSPORT AND LOW STATIC STABILITIES ABOVE H7 ON THE SRN FRINGE COULD PRODUCE SHORT LIVED BUT MODERATE/HEAVY SNOWS AND LOW VSBYS. DENDRITIC LAYER UVM ALSO SUGGESTS HIGHER POPS MAY HAVE TO BE PULLED SWD IF TRENDS CONTINUE...BUT SOUNDINGS ALSO SHOW DRIER LOW LEVELS WHICH COULD REDUCE ITS EFFECTIVENESS. .LONG TERM.../SAT THROUGH TUE/ NOT MANY CHANGES IN THIS PERIOD WITH GFS NOW TRENDING TOWARD DEEPER ECMWF SOLUTION. SYSTEM EARLY IN THE WEEK THE PRIMARY CONCERN...BUT WITH CLOSED LOW APPEARING TO BE PASSING TO OUR NORTH IA SHOULD NOT SEE TOO MUCH IN THE WAY OF PRECIP. BACKED OFF TO SLIGHT WORDING SUN AND SWITCHED PRECIP MORE TOWARD SNOW OUTSIDE OF CENTRAL SECTIONS MONDAY DURING PEAK HEATING. && .AVIATION...19/12Z WINDS HAVE SHIFTED TO THE NORTHWEST AT ALL TAF SITES...WITH GUSTY WINDS EXPECTED THROUGH THE AFTERNOON AT MOST NORTHERN TAF SITES SITUATED BEHIND THE COLD FRONT DROPPING SOUTHWARD THROUGH THE CWA TODAY. EXPECT GUSTINESS AT BOTH KDSM AND KOTM BY MID/LATE AFTERNOON...WITH ALL SITES REMAINING ABOVE THE 12KT THRESHOLD THROUGH THURSDAY MORNING. CONCERNS STILL ON PROGRESSION OF LOW STRATUS DECK...BUT HAVE TRIED TO TIME TO LATEST MODEL SUITE SUGGESTING THAT THE STATUS DECK WILL CONTINUE TO EXPAND SOUTHWARD THROUGH THE AFTERNOON INTO THE EVENING. EXPECT MVFR/POSSIBLY IFR CIGS FOR ALL TAF SITES THROUGH TONIGHT...LIFTING TO MVFR/VFR CIGS BY THURSDAY MORNING. && .DMX WATCHES/WARNINGS/ADVISORIES...NONE. && $$ JWL/BSS/MJA ia AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GOODLAND KS 927 PM MST THU NOV 20 2008 .DISCUSSION...UPDATED GRIDS AND ZONES TO LOWER MIN TEMPERATURES TONIGHT. DEWPOINTS ARE CURRENTLY IN THE TEENS ACROSS THE FORECAST AREA. CLOUDS SHOULD CONTINUE TO DECREASE ALLOWING TEMPERATURES TO FALL INTO THE UPPER TEENS BEFORE WINDS SHIFT TO THE SOUTH. OTHERWISE NO OTHER CHANGES. FS && .PREV DISCUSSION... /ISSUED 335 PM MST THU NOV 20 2008/ FORECAST CONCERNS ARE THE TEMPERATURES IN THE SHORT TERM WITH AN EYE OF CONCERN LOOKING FOREWARD TO NEXT THURSDAY...THANKSGIVING DAY...FOLLOWING A COLD FRONT AND UPPER LOW THAT MOVE ACROSS THE TRI-STATE REGION. THE UPPER FLOW PATTERN IS IN A PROGRESSIVE MODE WITH FOUR DISCRETE SHORT WAVE TROUGHS MOVING EAST OF THE ROCKIES AND ACROSS THE MID SECTION OF THE COUNTRY DURING THE NEXT SEVEN DAYS. THAT WILL KEEP THE UPPER RIDGE GENERALLY IN PLACE OVER THE WESTERN U.S. WITH A LEE SURFACE TROUGH GENERALLY IN PLACE NEAR THE EASTERN COLORADO BORDER. THE LEE TROUGH WILL VACILLATE BACK AND FORTH ACROSS THE REGION AS A COUPLE OF WEAK COLD FRONTS WILL ALSO MOVE ACROSS THE REGION IN RESPONSE TO THE UPPER SHORT WAVES ON SUNDAY MORNING AND TUESDAY MORNING. SENSIBLE WEATHER ACROSS THE TRI-STATE REGION THROUGH THAT TIME...AS A RESULT...WILL REMAIN BENIGN WITH DRY CONDITIONS AND TEMPERATURES SLIGHTLY WARMER THAN AVERAGE FOR THIS TIME OF YEAR. ON WEDNESDAY EVENING/EARLY THURSDAY MORNING...A STRONGER UPPER TROUGH WILL DEEPEN IN THE LEE OF THE ROCKIES WITH A LOW CENTER OVER THE NORTHERN PLAINS MOVING THROUGH THE GREAT LAKES REGION ON FRIDAY. A COLD FRONT WILL MOVE THROUGH THE REGION WEDNESDAY NIGHT WITH TEMPERATURES A FEW DEGREES COOLER EXPECTED ON THANKSGIVING DAY. WITH THE PROGRESSIVE NATURE OF THE PATTERN...THERE WILL NOT BE ENOUGH TIME BETWEEN WAVES TO SET UP A GOOD NEAR SURFACE MOISTURE RETURN PATTERN ACROSS THE SOUTHERN AND CENTRAL HIGH PLAINS...SO THE TRI-STATE REGION IS EXPECTED TO REMAIN DRY ON THURSDAY WITH SOME GUSTY WINDS DURING THE DAY BEHIND THE FRONT. && .AVIATION...FOR THE 06Z TAFS...BAND OF STRATUS HAS FORMED ACROSS EASTERN COLORADO THIS EVENING. MVFR CONDITIONS WERE BRIEFLY REPORTED AT KITR. RUC INDICATES THAT MVFR CEILINGS WILL REMAIN WEST OF KGLD...BUT WILL INDICATE A FEW HOURS OF SCT-BKN CLOUDS AROUND 2500 FEET BASED ON SATELLITE TRENDS. OTHERWISE...CONDITIONS WILL BE VFR THROUGH THE PERIOD AT BOTH KGLD AND KMCK. SURFACE WINDS WILL BECOME SOUTH AT 15-25 KNOTS AFTER 14Z. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...NONE. NE...NONE. CO...NONE. && $$ ks AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TOPEKA KS 526 PM CST WED NOV 19 2008 .UPDATE... UPDATED THE AVIATION DISCUSSION FOR THE 00Z TAFS. && .DISCUSSION... SEE PREV DISCUSSION. && .AVIATION... DRY AIR WILL PRECLUDE ANY PRECIP IN THE TERMINALS THROUGH 06Z FRI. MAIN CONCERN THIS EVENING IS STRATUS UPSTREAM. RUC AND NAM FORECAST SOUNDINGS PROG CIGS BETWEEN 1000 AND 1500 FEET. NOTED THE SOUTHERN EDGE OF THE STRATUS WAS MAKING SLOWER PROGRESS SOUTH ON LATEST SATELLITE. THOUGH DO NOT SEE WHY IT WOULD NOT HOLD TOGETHER AND MOVE INTO THE TERMINALS. INCLUDED A TEMPO FOR MVFR CIGS CLOSER TO THE TIMING OF THE NAM SOUNDINGS BASED ON LATEST SATELLITE TRENDS. WOLTERS && .PREV DISCUSSION.../354 PM CST WED NOV 19 2008/ THE 19Z WATER VAPOR SATELLITE IMAGERY ALONG WITH THE 12Z UPPER AIR MAPS SHOWED A DEEP TROUGH OVER THE EAST CENTRAL PACIFIC WITH DOWN STREAM UPPER RIDGE ACROSS THE WESTERN US. A DEEP TROUGH WAS MOVING OFF THE NEW ENGLAND COAST. AN UPPER TROUGH OVER SOUTH CENTRAL CANADA WAS DIGGING SOUTHEAST INTO THE NORTHERN PLAINS...WHILE A SECOND UPPER TROUGH WAS DIGGING SOUTHEAST ACROSS THE GREAT LAKES STATES. THE 19Z SURFACE MAPS SHOWED THE SFC COLD FRONT EXTENDING FROM NORTHWEST OK...NORTHEAST ACROSS THE CWA...GENERALLY ALONG THE KS TURNPIKE...NORTHEAST ACROSS NORTHERN MO. TEMPERATURES DIRECTLY BEHIND TO FRONT WERE ACTUALLY IN THE MID TO UPPER 60S. THE COLD AIR WAS LAGGING FAR BEHIND THE FRONT ACROSS NORTHERN NE. TONIGHT AND THURSDAY...THE 5H TROUGH OVER SOUTH CENTRAL CANADA WILL DIG SOUTHEAST ACROSS THE NORTHERN PLAINS AND AMPLIFY ACROSS THE MIDWEST AND GREAT LAKES STATES ON THU. LOW-LEVEL CAA WILL BUILD A 1044MB SFC RIDGE SOUTHWARD ACROSS THE PLAINS STATES. WINDS ABOVE THE SURFACE WILL INCREASE TONIGHT AND THURSDAY WITH 45KT NORTH WINDS AT 850MB. WINDS TONIGHT WILL INCREASE AS THE SFC RIDGE BUILDS SOUTH...THOUGH WINDS WILL SHARPLY INCREASE AFTER 14Z ONCE TH MIXED BL INCREASES. NORTH WINDS WILL INCREASE TO 15 TO 25 MPH WITH GUSTS OF 30 TO 35 MPH WILL BE POSSIBLE THROUGH THE LATE MORNING AND EARLY AFTERNOON HOURS ACROSS THE CWA. THERE IS AN AREA OF STRATUS OVC ACROSS THE NORTHERN PLAINS FROM NORTHERN NE NORTHWARD TO THE CANADIAN BORDER. NAM FCST SOUNDINGS SHOW THAT MOST OF BKN STRATUS SHOULD REMAIN ACROSS THE EXTREME NORTHEAST COUNTIES OF THE CWA LATE TONIGHT AND EARLY THU...THOUGH WE WILL PROBABLY SEE AT LEAST SOME SCT STRATUS MOVING SOUTH ACROSS THE ENTIRE CWA AFTER SUNRISE...THOUGH I CANNOT RULE OUT SOME BKN AREAS OF STRATUS THROUGH THE LATE MORNING HOURS. THE LOW-LEVEL CAA WILL KEEP HIGH TEMPERATURES FROM THE UPPER 30S TO LOWER 40S ACROSS THE CWA. THE GUSTY NORTH WINDS ON THU WILL MAKE IT FEEL LIKE ITS ONLY THE 20S AND 30S. SOME HIGH CLOUDS MAY LINGER ACROSS THE CWA IN THE EVENING...ALTHOUGH THE OVERNIGHT HOURS WILL GENERALLY BE CLEAR AS WINDS DIMINISH AS THE CENTER OF THE CANADIAN HIGH MOVES INTO THE CWA BY 12Z FRIDAY. WITH THE WINDS DROPPING OFF...CLEAR SKIES AND VERY DRY AIR OVERSPREADING THE CWA...TEMPERATURES WILL STEADILY FALL THROUGH THE NIGHT INTO THE MIDDLE TO UPPER TEENS. THEREFORE LOWERED PREVIOUS LOWS BY SEVERAL DEGREES. ALTHOUGH FRIDAY WILL BE MOSTLY SUNNY...TEMPS WILL BE A CHALLENGE AS THE DAYS STARTS OFF COLD AND DEGREE OF MIXING ON THE BACKSIDE OF THE RETREATING HIGH PRESSURE CENTER IS IN QUESTION. THE WESTERN AREAS OF THE CWA WILL HAVE THE BEST OPPORTUNITY TO EXPERIENCE WAA AND STRONGER MIXING BY AFTERNOON. THE GFS IS MUCH MORE AGGRESSIVE WITH THE VEERED LLVL FLOW AND RESULTANT WAA THAN THE NAM. WILL GO WITH A COMPROMISE WITH HIGHS FROM THE MID 30S FAR NORTHEAST CORNER TO THE LOWER 40S NORTH CENTRAL AND EAST CENTRAL AREAS. STRONGER WAA WILL TAKE PLACE OVERNIGHT AHEAD OF ANOTHER SHORTWAVE ADVANCING EASTWARD ACROSS THE NORTHERN PLAINS. THERE IS THE POSSIBILITY OF LOWS OCCURING IN THE EVENING ACROSS THE NORTHEASTERN CWA WITH STRONG WAA OVERNIGHT. WILL LIMIT DIURNAL DROP TO ONLY AROUND 10 DEGREES MOST AREAS. WITH THE DRY AIR IN THE LOW AND MID LEVEL HOLDING FIRM AND THE STRONGEST FORCING NORTH OF THE CWA...WILL KEEP FCST DRY FOR NOW AND ONLY INCREASE CLOUDS SOME ACROSS THE NORTH. THIS WILL SET THE STAGE FOR A WARMER DAY ON SATURDAY WITH HIGHS IN THE UPPER 40S TO LOWER 50S BEFORE ANOTHER SHORTWAVE IN NORTHWEST FLOW PUSHES ANOTHER FRONT INTO THE CWA ON SUNDAY. WHAT LIMITED MOISTURE RETURN THERE IS...WILL PRIMARILY GET PUSHED MORE TO THE EAST OF THE CWA SO ONLY A SLIGHT CHANCE FOR SHOWERS ACROSS THE EASTERN CWA...AND IF TRENDS CONTINUE...MAY NEED TO BE REMOVE IN LATER FCSTS. WITH THE FRONT ARRIVING LATER IN THE DAY...WILL KEEP HIGHS IN THE LOWER 50S MOST AREAS...THEN MAINLY 45 TO 50 FOR MONDAY BEHIND THE FRONT. LEANED MORE WITH THE ECMWF SOLN BY MID WEEK WITH LARGER SCALE TROUGH ON THE EAST AND WEST COASTS WITH MODERATING TEMPS BENEATH UPPER RIDGING ACROSS THE PLAINS. HAVE PUSHED HIGHS BY WEDNESDAY BACK INTO THE LOW TO MID 50S MOST AREAS AND KEPT THE FCST DRY. && .TOP WATCHES/WARNINGS/ADVISORIES...NONE. && $$ ks AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DODGE CITY KS 249 PM CST WED NOV 19 2008 .DISCUSSION... DAYS 1-2... THE MAIN FORECAST CHALLENGE WILL BE TEMPERATURES. 12Z UA ANALYSIS SHOWED STRONG MID/UPPER LEVEL FLOW EXTENDING FROM ALONG THE U.S./CANADIAN BORDER NEAR WASHINGTON STATE THROUGH THE GREAT LAKES INTO THE MID ATLANTIC STATES. A FAST MOVING SHORTWAVE TROUGH WAS MOVING INTO THE GREAT LAKES REGION. A WEAK SHORTWAVE TROUGH WAS MOVING THROUGH THE CENTRAL HIGH PLAINS THIS TODAY. THIS SYSTEM HAD PUSHED A WIND SHIFT THROUGH SOUTHWEST KANSAS THIS MORNING. A STRONGER COLD FRONT...ASSOCIATED WITH THE GREAT LAKES SHORTWAVE...WAS MOVING SOUTH THROUGH CENTRAL NEBRASKA THIS AFTERNOON. VISIBLE SATELLITE IMAGERY SHOWED A STRATUS DECK MOVING INTO NORTHERN NEBRASKA THIS AFTERNOON BEHIND THE FRONT. THE COLDER AIR WILL BE MOVING SOUTH INTO WESTERN KANSAS TONIGHT WITH THE STRATUS DEVELOPING SOUTHWARD INTO THE CWA OVERNIGHT. NOT SURE WHAT THE AREAL EXTENT WILL BE AS IT CURRENTLY IS NOT REAL EXTENSIVE ACROSS SOUTH DAKOTA. THINK THAT THE COLD AIR ADVECTION COMBINED WITH SOME MECHANICAL COOLING IN THE UPSLOPE AREAS WILL RESULT IN IT COVERING AT LEAST THE NORTHWEST HALF OF THE CWA BY 12Z THURSDAY IF NOT FARTHER SOUTHEAST. THE LOW CLOUDINESS MAY DIMINISH SOMEWHAT DURING THE DAY THURSDAY BUT MODEL SOUNDINGS SHOW A SATURATED LAYER AROUND 6-8 KFT DURING THE DAY. UVV WILL BE INCREASING AS THE UPPER JET SAGS SOUTH AND THE CWA COMES UNDER THE RIGHT ENTRANCE REGION SO FEEL THAT BROKEN LAYERS OF CLOUDS WILL BE AROUND. THE MODELS SPIT OUT SOME LIGHT QPF AMOUNTS BUT KEEP IT BACKED UP AGAINST THE EASTERN SLOPES OF THE ROCKIES WILL SEEMS REASONABLE FOR NOW. ON THURSDAY NIGHT AND FRIDAY ANOTHER SHORTWAVE TROUGH WILL BE MOVING OUT OF THE NORTHERN ROCKIES INTO THE NORTHERN PLAINS. A SURFACE TROUGH WILL DEEPEN OVER THE CENTRAL HIGH PLAINS IN RESPONSE. TEMPERATURES SHOULD BE CLIMBING INTO THE MID 50S OR ABOVE IN THE WESTERN CWA BUT WILL PROBABLY STRUGGLE TO GET OUT OF THE 40S IN THE EAST. SOUTHERLY WINDS WILL PICK UP DURING THE DAY AND... WITH THE FAIRLY TIGHT SURFACE PRESSURE GRADIENT FORECAST...MAY BE APPROACHING ADVISORY SPEEDS. DAYS 3-7... THE PERIOD STARTS WITH ALL MEDIUM RANGE MODELS CALLING FOR WEST TO NORTHWESTERLY FLOW OVER THE PLAINS. THE LEE TROUGH SHOULD RE-DEVELOP BY SATURDAY, AND SOUTHERLY WINDS WILL BRING A FAIRLY WARM DAY WITH HIGHS IN THE MID 50S. ANOTHER SHORTWAVE TROUGH WILL MOVE INTO THE NORTHERN PLAINS ON SUNDAY, WITH SOME DIFFERENCES BETWEEN THE MODELS ON STRENGTH AND EXACT TIMING. THIS SYSTEM SHOULD HELP PUSH ANOTHER COLD FRONT DOWN INTO THE CENTRAL PLAINS ON SUNDAY, WITH THE ECMWF ABOUT 6 HRS FASTER THAN THE GFS. HIGHS WILL DEPEND ON WHEN THE FRONT COMES THROUGH, BUT WILL CONTINUE TO KEEP OUR NORTHERN CWA COOLER IN THE LOWER 50S WITH SOMEWHAT WARMER READINGS IN THE SOUTH. DETERMINISTIC MODELS AND ENSEMBLES ARE IN AGREEMENT WITH THE TRUE COLD AIR ARRIVING MONDAY AS THE UPPER SHORTWAVE DIGS INTO THE GREAT LAKES AND SFC HIGH PRESSURE BUILDS DOWN. AGAIN, THERE ARE DIFFERENCES IN HOW MUCH COLD AIR GETS INTO THE CWA, WITH THE ECMWF DROPPING 850MB TEMPS BELOW ZERO WHILE THE GFS HAS US IN THE LOWER SINGLE DIGITS C. IT DEPENDS ON HOW FAR WEST THE UPPER TROUGH DIGS, BUT ESRL RE-FORECAST AND NAEFS ENSEMBLES LEAN TOWARDS THE WARMER SOLUTION. WILL KEEP HIGHS MONDAY IN THE UPPER 40S TO LOW 50S, BUT FULLY EXPECT TO ADJUST AS THE TIME GETS CLOSER. TEMPS SHOULD WARM A BIT ON TUESDAY AS THE UPPER TROUGH CONTINUES EAST AND THE RIDGE STARTS INTO THE WESTERN PLAINS. MODEL CONSENSUS STARTS DOWNHILL AFTER DAY 6, WITH THE NEXT SIGNIFICANT WAVE COMING ONTO THE WEST COAST AND OUT TOWARDS THE PLAINS. THE ECMWF CONTINUES TO BE FASTER THAN THE GFS AND EVEN THE ENSEMBLE MEANS, BRINGING THE TROUGH THROUGH THE DESERT SOUTHWEST BY NEXT THURSDAY. DPROG/DT HAS NOT BEEN VERY CONSISTENT, BUT IT DOES LOOK LIKE THERE WILL BE SOME SORT OF SYSTEM DIGGING INTO THE SOUTHWESTERN CONUS AROUND DAYS 8-10. EVEN WITH THE VARIATIONS ON TIMING, ENSEMBLE PROBABILITIES SHOW US PRETTY DRY THROUGH THE MIDDLE OF NEXT WEEK, THEN BECOMING MORE WET INTO THE HOLIDAY WEEKEND. WILL KEEP THE GRIDS DRY FOR NOW, BUT PUT ABOVE NORMAL PRECIP IN FOR THE WEEK TWO FORECAST. && .AVIATION... NORTH TO NORTHEASTERLY WINDS WILL CONTINUE THROUGH TONIGHT AND TOMORROW AS HIGH PRESSURE DIGS INTO THE PLAINS. VFR CONDITIONS WILL CONTINUE FOR THE NEXT 12 TO 14 HOURS OR SO. RUC HAS LOW CEILINGS TOWARDS MORNING, ALTHOUGH THE NAM IS NOT SHOWING AS MUCH SATURATION AT LOWER LEVELS. STRATUS IS EVIDENT IN NORTHERN NEB, WHICH COULD START COMING DOWN INTO THE CWA TOWARDS MORNING. WITH UPSLOPE, THINK THAT THE LOWEST CEILINGS WILL BE MAINLY TO THE WEST OF THE TAF SITES, BUT KGCK COULD GET DOWN TO MVFR CONDITIONS. WILL HAVE TO KEEP AN EYE ON TAF SITES AS ALL LOCATIONS GOING DOWN TO MVFR OR IFR ARE NOT OUT OF THE QUESTION. && .PRELIMINARY POINT TEMPS/POPS... DDC 29 41 23 50 / 0 0 0 0 GCK 28 40 23 52 / 0 0 0 0 EHA 31 40 25 55 / 0 0 0 0 LBL 30 41 25 54 / 0 0 0 0 HYS 28 39 21 48 / 0 0 0 0 P28 33 45 25 49 / 0 0 0 0 && .DDC WATCHES/WARNINGS/ADVISORIES... NONE. && $$ FN02/26 ks AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE JACKSON KY 1229 AM EST THU NOV 20 2008 .SHORT TERM.../THE REST OF TONIGHT/ AN AREA OF LOW PRESSURE IS MOVING THROUGH THE GREAT LAKES...WITH A COLD FRONT TRAILING DOWN INTO THE LOWER OH VALLEY...JUST TO THE NW OF THE OH RIVER ATTM. MOISTURE IN THE LOWER LEVELS IS INCREASING SLOWLY AHEAD OF THE BOUNDARY. IN ADDITION...A SFC TROUGH LIES NEAR THE KY/WV BORDER...WITH SFC DEWPOINTS GRADUALLY INCREASING TO THE SW OF THIS BOUNDARY. THE LOWER DEWPOINTS IN THE LOWER TEENS ARE GENERALLY CONFINED TO THE RIDGETOPS...WHILE VALLEY LOCATIONS APPEAR TO HAVE DEWPOINTS NEAR 20 BASED ON SFC OBS/MESONET. UPSTREAM...LOW CLOUDS WERE OVER OH AND ARE NEARING THE OH RIVER...WHILE AN EXTENSIVE AREA OF CLEAR SKIES WAS OVER MUCH OF KY AND PARTS OF SOUTHERN MO...IL AND IN...THOUGH ADDITIONAL POST FRONTAL LOW CLOUDS WERE OVER IA...NORTHERN IL AND NORTHERN MO. BASED ON MODEL FORECASTS OF RH BETWEEN 925 AND 850 MB AS WELL AS EXTRAPOLATION OF THE UPSTREAM CLOUDS...OPTED TO INCREASE CLOUDS FOR THE REMAINDER OF THE NIGHT...ESPECIALLY AFTER 6Z. THE NAM AND RUC ARE MORE OPTIMISTIC THAN THE GFS...SO CONFIDENCE IS NOT ALL THAT HIGH...ESPECIALLY WITH SKY COVER ON THU. HOWEVER...IT APPEARS THAT FOR AN HOUR OR TWO EITHER SIDE OF FROPA...SKIES WILL BE AT LEAST BROKEN...ESPECIALLY OVER THE NE TWO THIRDS OF THE CWA. OTHERWISE...THE VALLEYS...ESPECIALLY IN THE EASTERN COUNTIES HAVE EXPERIENCED TEMPS FALLING OFF QUICKER THAN FORECAST...SO MADE SOME SLIGHT ADJUSTMENTS TO THE HOURLY TEMP CURVE...WITH TEMP FALL IN THOSE AREAS STOPPING AROUND 9Z OR ABOUT THE TIME CLOUDS INCREASE...BUT DID NOT CHANGE THE OVERNIGHT LOWS AS THEY STILL APPEARED REASONABLE. OTHERWISE...NO ADDITIONAL CHANGES. THE PREVIOUS SHORT TERM FORECAST DISCUSSION FOLLOWS... /TONIGHT THROUGH FRIDAY NIGHT/ A COLD FRONT OVER THE MIDWEST WILL ENTER KY TONIGHT AND PASS THROUGH THE FORECAST AREA ON THURSDAY MORNING. MODELS ADVECT A MEAGER AMOUNT OF LOW LEVEL MOISTURE INTO THE AREA JUST AHEAD OF THE FRONT. THE GFS GENERATES LOW CLOUDS FROM IT OVERNIGHT...WHILE THE WRF IS NOT QUITE AS MOIST. HAVE OPTED TO LEAN TOWARD THE WRF...THINKING THAT IF CLOUDS DO DEVELOP...IT WILL NOT BE UNTIL NEAR DAWN...LEAVING TONIGHT MAINLY CLEAR. BEHIND THE FRONT...THE WRF ALLOWS MORE WARMING ON THURSDAY THAN THE GFS. AM INCLINED TO BELIEVE IT DUE TO ITS ABILITY TO BETTER HANDLE THE EFFECTS OF TERRAIN ON THE FRONT CROSSING THE MOUNTAINS. WITH COLD AIR ADVECTION...LAPSE RATES WILL STEEPEN AND THE MIXING LAYER WILL DEEPEN...PROMOTING CU DEVELOPMENT. IT WILL BE COLD ENOUGH WITH DEEP ENOUGH MOISTURE ON THURSDAY NIGHT FOR FLURRIES AND SNOW SHOWERS TO DEVELOP IN THE UPSLOPE LOW LEVEL FLOW OFF OF LAKE MICHIGAN. THE MOST FAVORABLE LOCATION FOR THIS WILL BE IN OUR EASTERN COUNTIES. HOWEVER...LITTLE OR NO ACCUMULATION IS EXPECTED. ANY REMAINING SNOW WILL END ON FRIDAY AS SURFACE HIGH PRESSURE BUILDS IN FROM THE WEST...AND THE COLD AIR ADVECTION AND TRAJECTORY OFF OF LAKE MICHIGAN END. SKIES SHOULD CLEAR OUT BY FRIDAY NIGHT. THERE COULD BE SOME MID AND HIGH CLOUDS SHOWING UP LATE FRIDAY NIGHT FROM A SHORTWAVE IN THE NW FLOW ALOFT. THE WRF AND GFS DIFFER ON TIMING OF THIS. THE 00Z GFS ENSEMBLE MEAN LOOKS SLOWER THAN THE OPERATIONAL RUN...SO WILL GO WITH MOSTLY CLEAR SKIES. WILL LOOK FOR NOTABLE RIDGE/VALLEY TEMPERATURE DIFFERENCE TONIGHT...AND TO A SLIGHTLY LESSER EXTENT ON FRIDAY NIGHT. COLD AIR ADVECTION WILL SHOULD KEEP THE AIR MIXED WELL ENOUGH TO PREVENT MUCH SEPARATION ON THURSDAY NIGHT. .LONG TERM.../SATURDAY THROUGH WEDNESDAY/ THE 12Z RUNS OF THE GFS AND ECMWF WERE BOTH IN GOOD AGREEMENT WITH REGARD TO AN AREA OF LOW PRESSURE THAT WILL MOVE ACROSS THE GREAT LAKES AND INTO NEW ENGLAND MONDAY THROUGH TUESDAY NIGHT. THE GENERAL TIMING OF THIS SYSTEMS TRAILING COLD IS TO MOVE THE BOUNDARY ACROSS CENTRAL AND EASTERN KENTUCKY ON MONDAY. PRECIPITATION WILL START OUT ALL RAIN AHEAD OF THE FRONT ON MONDAY AFTERNOON AND EVENING. A MIX OF RAIN AND SNOW WILL BEGIN TO FALL AROUND 8 OR 9Z MONDAY NIGHT...WITH A BRIEF CHANGE OVER TO ALL SNOW BETWEEN 10 AND 13Z ON TUESDAY MORNING. THE HIGHER TERRAIN ALONG THE VIRGINIA AND WEST VIRGINIA BORDERS WILL LIKELY SEE MOSTLY SNOW THROUGHOUT THE DAY ON TUESDAY AND TUESDAY NIGHT. LITTLE IF ANY SNOW ACCUMULATION IS EXPECTED OVERALL...BUT A LIGHT DUSTING COULD OCCUR ALONG THE HIGHEST RIDGE TOPS NEAR THE VIRGINIA AND WEST VIRGINIA BORDERS. ALSO DECIDED TO INCREASE PRECIP CHANCES A BIT FOR MONDAY AND MONDAY AFTERNOON...AS THE MODELS ARE SHOWING GOOD MID AND UPPER LEVEL JET INTERACTION ACROSS THE OHIO VALLEY DURING THE DAY ON MONDAY. THE 12Z GFS MODEL SOUNDINGS DID SHOW SOME INDICATIONS OF POTENTIAL FREEZING RAIN FOR EARLY MONDAY MORNING...BUT THIS WAS QUITE A CHANGE FROM THE 6Z RUNS AND WITH THE AMOUNT OF UNCERTAINTY REGARDING THIS...WILL HOLD OFF ON MENTION OF ANY FROZEN PRECIP FOR NOW...INSTEAD GOING WITH SNOW OR A RAIN SNOW MIX. MOIST NORTHWEST FLOW BEHIND THE DEPARTING UPPER LOW WILL BE THE IMPETUS FOR CONTINUED SCATTERED LIGHT RAIN AND SHOW SHOWERS TUESDAY NIGHT THROUGH WEDNESDAY AFTERNOON...WITH A TYPICAL UPSLOPE PATTERN SETTING UP. WITH STRONG HIGH PRESSURE BUILDING ACROSS THE AREA OVER THE WEEKEND...DECIDED TO DECREASE CLOUD COVER A BIT AS WELL. MODEL SOUNDINGS AND TIME HEIGHT CROSS SECTIONS ALSO SUPPORTED THIS. SKY COVER FORECAST FOR MONDAY THROUGH WEDNESDAY WAS LEFT ESSENTIALLY THE SAME AS BEFORE...WITH THE PRIMARY LONG RANGE MODELS IN GOOD AGREEMENT WITH THE TIMING OF THE NEXT WEATHER MAKER FOR ALL THREE DAYS. THE MODEL DATA SUPPORT SLIGHTLY COOLER TEMPERATURES FOR SATURDAY AND SUNDAY THAN THE MOS DATA REFLECTS...SO WENT A BIT COOLER FOR HIGHS ON SATURDAY AND SUNDAY. TEMPERATURES ON MONDAY...TUESDAY...AND WEDNESDAY WILL BE COOLER THAN THE LATEST MOS NUMBERS DUE TO THE EXPECTED CLOUD COVER AND PRECIPITATION...THEREFORE...ADJUSTMENTS WERE MADE TO ACCOUNT FOR THESE FACTORS. OVERNIGHT LOW TEMPERATURES WILL STAY FAIRLY STEADY ON EACH NIGHT THAT HAS LOTS OF CLOUD COVER. THE HPC GUIDANCE WAS FAVORED HERE...SO WENT SLIGHTLY WARMER THAN HPC MOS ACROSS THE BOARD FOR OVERNIGHT LOWS THROUGH TUESDAY NIGHT. DEWPOINTS AND WINDS WERE ALSO TWEAKED SLIGHTLY. THE DEWPOINTS APPEARED TO BE A BIT TOO HIGH COMPARED TO THE LATEST SURFACE OBS AND THE LAST TWO RUNS OF MEXMOS...AS A RESULT...DEW POINTS WERE DECREASED A BIT FOR THE MAJORITY OF THE EXTENDED FORECAST PERIOD. WINDS WERE ALSO ADJUSTED SLIGHTLY TO ACCOUNT FOR THE MINOR CHANGES MADE TO THE TIMING OF THE FRONTAL PASSAGE ON MONDAY AND MONDAY NIGHT. && .AVIATION.../06Z TO 06Z/...UPDATED A COLD FRONT EXTENDING FROM WESTERN LAKE ERIE TO WESTERN KENTUCKY INTO OKLAHOMA. THIS FRONT SHOULD REACH THE TAFS SITES AROUND 10-11Z. TAMDAR AND MODEL DATA INDICATE LLWS WITH WINDS 270 AT 35KT AT 1500 FT. THE LLWS WILL END AFTER AROUND FROPA. EXPECTING STRATOCU AROUND AT 4-5 KFT IN THE AREA OVERNIGHT...WITH CIGS DEVELOPING AT JKL AND LOZ. EXPECTING GUSTY WNW WINDS DURING THE DAY THURSDAY...WITH CONTINUED BKN STRATOCU. CIGS SHOULD BEGIN TO LOWER LATE IN THE PERIOD AS UPSLOPE FLOW AND A MOISTURE CONNECTION OFF THE GREAT LAKES BRING A FEW SNOW SHOWERS TO THE AREA. && .JKL WATCHES/WARNINGS/ADVISORIES...NONE. && $$ SHORT TERM...HAL/JP LONG TERM....AR AVIATION...WJM ky AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE JACKSON KY 1019 PM EST WED NOV 19 2008 .SHORT TERM.../THE REST OF TONIGHT/...UPDATED AN AREA OF LOW PRESSURE IS MOVING THROUGH THE GREAT LAKES...WITH A COLD FRONT TRAILING DOWN INTO THE LOWER OH VALLEY...JUST TO THE NW OF THE OH RIVER ATTM. MOISTURE IN THE LOWER LEVELS IS INCREASING SLOWLY AHEAD OF THE BOUNDARY. IN ADDITION...A SFC TROUGH LIES NEAR THE KY/WV BORDER...WITH SFC DEWPOINTS GRADUALLY INCREASING TO THE SW OF THIS BOUNDARY. THE LOWER DEWPOINTS IN THE LOWER TEENS ARE GENERALLY CONFINED TO THE RIDGETOPS...WHILE VALLEY LOCATIONS APPEAR TO HAVE DEWPOINTS NEAR 20 BASED ON SFC OBS/MESONET. UPSTREAM...LOW CLOUDS WERE OVER OH AND ARE NEARING THE OH RIVER...WHILE AN EXTENSIVE AREA OF CLEAR SKIES WAS OVER MUCH OF KY AND PARTS OF SOUTHERN MO...IL AND IN...THOUGH ADDITIONAL POST FRONTAL LOW CLOUDS WERE OVER IA...NORTHERN IL AND NORTHERN MO. BASED ON MODEL FORECASTS OF RH BETWEEN 925 AND 850 MB AS WELL AS EXTRAPOLATION OF THE UPSTREAM CLOUDS...OPTED TO INCREASE CLOUDS FOR THE REMAINDER OF THE NIGHT...ESPECIALLY AFTER 6Z. THE NAM AND RUC ARE MORE OPTIMISTIC THAN THE GFS...SO CONFIDENCE IS NOT ALL THAT HIGH...ESPECIALLY WITH SKY COVER ON THU. HOWEVER...IT APPEARS THAT FOR AN HOUR OR TWO EITHER SIDE OF FROPA...SKIES WILL BE AT LEAST BROKEN...ESPECIALLY OVER THE NE TWO THIRDS OF THE CWA. OTHERWISE...THE VALLEYS...ESPECIALLY IN THE EASTERN COUNTIES HAVE EXPERIENCED TEMPS FALLING OFF QUICKER THAN FORECAST...SO MADE SOME SLIGHT ADJUSTMENTS TO THE HOURLY TEMP CURVE...WITH TEMP FALL IN THOSE AREAS STOPPING AROUND 9Z OR ABOUT THE TIME CLOUDS INCREASE...BUT DID NOT CHANGE THE OVERNIGHT LOWS AS THEY STILL APPEARED REASONABLE. OTHERWISE...NO ADDITIONAL CHANGES. THE PREVIOUS SHORT TERM FORECAST DISCUSSION FOLLOWS... /TONIGHT THROUGH FRIDAY NIGHT/ A COLD FRONT OVER THE MIDWEST WILL ENTER KY TONIGHT AND PASS THROUGH THE FORECAST AREA ON THURSDAY MORNING. MODELS ADVECT A MEAGER AMOUNT OF LOW LEVEL MOISTURE INTO THE AREA JUST AHEAD OF THE FRONT. THE GFS GENERATES LOW CLOUDS FROM IT OVERNIGHT...WHILE THE WRF IS NOT QUITE AS MOIST. HAVE OPTED TO LEAN TOWARD THE WRF...THINKING THAT IF CLOUDS DO DEVELOP...IT WILL NOT BE UNTIL NEAR DAWN...LEAVING TONIGHT MAINLY CLEAR. BEHIND THE FRONT...THE WRF ALLOWS MORE WARMING ON THURSDAY THAN THE GFS. AM INCLINED TO BELIEVE IT DUE TO ITS ABILITY TO BETTER HANDLE THE EFFECTS OF TERRAIN ON THE FRONT CROSSING THE MOUNTAINS. WITH COLD AIR ADVECTION...LAPSE RATES WILL STEEPEN AND THE MIXING LAYER WILL DEEPEN...PROMOTING CU DEVELOPMENT. IT WILL BE COLD ENOUGH WITH DEEP ENOUGH MOISTURE ON THURSDAY NIGHT FOR FLURRIES AND SNOW SHOWERS TO DEVELOP IN THE UPSLOPE LOW LEVEL FLOW OFF OF LAKE MICHIGAN. THE MOST FAVORABLE LOCATION FOR THIS WILL BE IN OUR EASTERN COUNTIES. HOWEVER...LITTLE OR NO ACCUMULATION IS EXPECTED. ANY REMAINING SNOW WILL END ON FRIDAY AS SURFACE HIGH PRESSURE BUILDS IN FROM THE WEST...AND THE COLD AIR ADVECTION AND TRAJECTORY OFF OF LAKE MICHIGAN END. SKIES SHOULD CLEAR OUT BY FRIDAY NIGHT. THERE COULD BE SOME MID AND HIGH CLOUDS SHOWING UP LATE FRIDAY NIGHT FROM A SHORTWAVE IN THE NW FLOW ALOFT. THE WRF AND GFS DIFFER ON TIMING OF THIS. THE 00Z GFS ENSEMBLE MEAN LOOKS SLOWER THAN THE OPERATIONAL RUN...SO WILL GO WITH MOSTLY CLEAR SKIES. WILL LOOK FOR NOTABLE RIDGE/VALLEY TEMPERATURE DIFFERENCE TONIGHT...AND TO A SLIGHTLY LESSER EXTENT ON FRIDAY NIGHT. COLD AIR ADVECTION WILL SHOULD KEEP THE AIR MIXED WELL ENOUGH TO PREVENT MUCH SEPARATION ON THURSDAY NIGHT. .LONG TERM.../SATURDAY THROUGH WEDNESDAY/ THE 12Z RUNS OF THE GFS AND ECMWF WERE BOTH IN GOOD AGREEMENT WITH REGARD TO AN AREA OF LOW PRESSURE THAT WILL MOVE ACROSS THE GREAT LAKES AND INTO NEW ENGLAND MONDAY THROUGH TUESDAY NIGHT. THE GENERAL TIMING OF THIS SYSTEMS TRAILING COLD IS TO MOVE THE BOUNDARY ACROSS CENTRAL AND EASTERN KENTUCKY ON MONDAY. PRECIPITATION WILL START OUT ALL RAIN AHEAD OF THE FRONT ON MONDAY AFTERNOON AND EVENING. A MIX OF RAIN AND SNOW WILL BEGIN TO FALL AROUND 8 OR 9Z MONDAY NIGHT...WITH A BRIEF CHANGE OVER TO ALL SNOW BETWEEN 10 AND 13Z ON TUESDAY MORNING. THE HIGHER TERRAIN ALONG THE VIRGINIA AND WEST VIRGINIA BORDERS WILL LIKELY SEE MOSTLY SNOW THROUGHOUT THE DAY ON TUESDAY AND TUESDAY NIGHT. LITTLE IF ANY SNOW ACCUMULATION IS EXPECTED OVERALL...BUT A LIGHT DUSTING COULD OCCUR ALONG THE HIGHEST RIDGE TOPS NEAR THE VIRGINIA AND WEST VIRGINIA BORDERS. ALSO DECIDED TO INCREASE PRECIP CHANCES A BIT FOR MONDAY AND MONDAY AFTERNOON...AS THE MODELS ARE SHOWING GOOD MID AND UPPER LEVEL JET INTERACTION ACROSS THE OHIO VALLEY DURING THE DAY ON MONDAY. THE 12Z GFS MODEL SOUNDINGS DID SHOW SOME INDICATIONS OF POTENTIAL FREEZING RAIN FOR EARLY MONDAY MORNING...BUT THIS WAS QUITE A CHANGE FROM THE 6Z RUNS AND WITH THE AMOUNT OF UNCERTAINTY REGARDING THIS...WILL HOLD OFF ON MENTION OF ANY FROZEN PRECIP FOR NOW...INSTEAD GOING WITH SNOW OR A RAIN SNOW MIX. MOIST NORTHWEST FLOW BEHIND THE DEPARTING UPPER LOW WILL BE THE IMPETUS FOR CONTINUED SCATTERED LIGHT RAIN AND SHOW SHOWERS TUESDAY NIGHT THROUGH WEDNESDAY AFTERNOON...WITH A TYPICAL UPSLOPE PATTERN SETTING UP. WITH STRONG HIGH PRESSURE BUILDING ACROSS THE AREA OVER THE WEEKEND...DECIDED TO DECREASE CLOUD COVER A BIT AS WELL. MODEL SOUNDINGS AND TIME HEIGHT CROSS SECTIONS ALSO SUPPORTED THIS. SKY COVER FORECAST FOR MONDAY THROUGH WEDNESDAY WAS LEFT ESSENTIALLY THE SAME AS BEFORE...WITH THE PRIMARY LONG RANGE MODELS IN GOOD AGREEMENT WITH THE TIMING OF THE NEXT WEATHER MAKER FOR ALL THREE DAYS. THE MODEL DATA SUPPORT SLIGHTLY COOLER TEMPERATURES FOR SATURDAY AND SUNDAY THAN THE MOS DATA REFLECTS...SO WENT A BIT COOLER FOR HIGHS ON SATURDAY AND SUNDAY. TEMPERATURES ON MONDAY...TUESDAY...AND WEDNESDAY WILL BE COOLER THAN THE LATEST MOS NUMBERS DUE TO THE EXPECTED CLOUD COVER AND PRECIPITATION...THEREFORE...ADJUSTMENTS WERE MADE TO ACCOUNT FOR THESE FACTORS. OVERNIGHT LOW TEMPERATURES WILL STAY FAIRLY STEADY ON EACH NIGHT THAT HAS LOTS OF CLOUD COVER. THE HPC GUIDANCE WAS FAVORED HERE...SO WENT SLIGHTLY WARMER THAN HPC MOS ACROSS THE BOARD FOR OVERNIGHT LOWS THROUGH TUESDAY NIGHT. DEWPOINTS AND WINDS WERE ALSO TWEAKED SLIGHTLY. THE DEWPOINTS APPEARED TO BE A BIT TOO HIGH COMPARED TO THE LATEST SURFACE OBS AND THE LAST TWO RUNS OF MEXMOS...AS A RESULT...DEW POINTS WERE DECREASED A BIT FOR THE MAJORITY OF THE EXTENDED FORECAST PERIOD. WINDS WERE ALSO ADJUSTED SLIGHTLY TO ACCOUNT FOR THE MINOR CHANGES MADE TO THE TIMING OF THE FRONTAL PASSAGE ON MONDAY AND MONDAY NIGHT. && .AVIATION.../00Z TO 24Z/ A COLD FRONT EXTENDING SOUTH FROM AN AREA OF LOW PRESSURE OVER THE NORTHERN GREAT LAKES WILL MOVE SOUTHEAST INTO THE OH VALLEY EARLY IN THE PERIOD AND THEN INTO THE APPALACHIANS AROUND 12Z. ALTHOUGH THERE ARE NOT MANY LOW CLOUDS AHEAD OF THE BOUNDARY...MODELS INDICATE SOME MOISTURE ADVECTION OVERNIGHT. NAM AND GFS DATA BOTH INDICATE SOME SATURATION IN THE MVFR RANGE CLOSE TO THE BOUNDARY FOR A COUPLE OF HOURS AROUND 9Z AS WELL AS IN THE MID CLOUD RANGE. STAYED CLOSE TO THE PREVIOUS FORECAST...WITH THIS...THOUGH SHORTENED THE LENGTH OF MVFR TO ABOUT 3 TO 4 HOURS CENTERED AROUND 9Z...MORE IN LINE WITH THE DRIER NAM AND RUC. LOW LEVEL DRYING SHOULD THEN OCCUR AS THE SFC HIGH BUILDS IN...THOUGH SOME STRATOCU AND CU SHOULD OCCUR THROUGH THE END OF THE PERIOD JUST BELOW THE SUBSIDENCE INVERSION. WINDS WILL ALSO SHIFT TO NW TO NWW BY 16Z BEHIND THE FRONT. && .JKL WATCHES/WARNINGS/ADVISORIES...NONE. && $$ SHORT TERM...HAL/JP LONG TERM....AR AVIATION...JP ky AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE JACKSON KY 732 PM EST WED NOV 19 2008 .SHORT TERM.../TONIGHT THROUGH FRIDAY NIGHT/ A COLD FRONT OVER THE MIDWEST WILL ENTER KY TONIGHT AND PASS THROUGH THE FORECAST AREA ON THURSDAY MORNING. MODELS ADVECT A MEAGER AMOUNT OF LOW LEVEL MOISTURE INTO THE AREA JUST AHEAD OF THE FRONT. THE GFS GENERATES LOW CLOUDS FROM IT OVERNIGHT...WHILE THE WRF IS NOT QUITE AS MOIST. HAVE OPTED TO LEAN TOWARD THE WRF...THINKING THAT IF CLOUDS DO DEVELOP...IT WILL NOT BE UNTIL NEAR DAWN...LEAVING TONIGHT MAINLY CLEAR. BEHIND THE FRONT...THE WRF ALLOWS MORE WARMING ON THURSDAY THAN THE GFS. AM INCLINED TO BELIEVE IT DUE TO ITS ABILITY TO BETTER HANDLE THE EFFECTS OF TERRAIN ON THE FRONT CROSSING THE MOUNTAINS. WITH COLD AIR ADVECTION...LAPSE RATES WILL STEEPEN AND THE MIXING LAYER WILL DEEPEN...PROMOTING CU DEVELOPMENT. IT WILL BE COLD ENOUGH WITH DEEP ENOUGH MOISTURE ON THURSDAY NIGHT FOR FLURRIES AND SNOW SHOWERS TO DEVELOP IN THE UPSLOPE LOW LEVEL FLOW OFF OF LAKE MICHIGAN. THE MOST FAVORABLE LOCATION FOR THIS WILL BE IN OUR EASTERN COUNTIES. HOWEVER...LITTLE OR NO ACCUMULATION IS EXPECTED. ANY REMAINING SNOW WILL END ON FRIDAY AS SURFACE HIGH PRESSURE BUILDS IN FROM THE WEST...AND THE COLD AIR ADVECTION AND TRAJECTORY OFF OF LAKE MICHIGAN END. SKIES SHOULD CLEAR OUT BY FRIDAY NIGHT. THERE COULD BE SOME MID AND HIGH CLOUDS SHOWING UP LATE FRIDAY NIGHT FROM A SHORTWAVE IN THE NW FLOW ALOFT. THE WRF AND GFS DIFFER ON TIMING OF THIS. THE 00Z GFS ENSEMBLE MEAN LOOKS SLOWER THAN THE OPERATIONAL RUN...SO WILL GO WITH MOSTLY CLEAR SKIES. WILL LOOK FOR NOTABLE RIDGE/VALLEY TEMPERATURE DIFFERENCE TONIGHT...AND TO A SLIGHTLY LESSER EXTENT ON FRIDAY NIGHT. COLD AIR ADVECTION WILL SHOULD KEEP THE AIR MIXED WELL ENOUGH TO PREVENT MUCH SEPARATION ON THURSDAY NIGHT. .LONG TERM.../SATURDAY THROUGH WEDNESDAY/ THE 12Z RUNS OF THE GFS AND ECMWF WERE BOTH IN GOOD AGREEMENT WITH REGARD TO AN AREA OF LOW PRESSURE THAT WILL MOVE ACROSS THE GREAT LAKES AND INTO NEW ENGLAND MONDAY THROUGH TUESDAY NIGHT. THE GENERAL TIMING OF THIS SYSTEMS TRAILING COLD IS TO MOVE THE BOUNDARY ACROSS CENTRAL AND EASTERN KENTUCKY ON MONDAY. PRECIPITATION WILL START OUT ALL RAIN AHEAD OF THE FRONT ON MONDAY AFTERNOON AND EVENING. A MIX OF RAIN AND SNOW WILL BEGIN TO FALL AROUND 8 OR 9Z MONDAY NIGHT...WITH A BRIEF CHANGE OVER TO ALL SNOW BETWEEN 10 AND 13Z ON TUESDAY MORNING. THE HIGHER TERRAIN ALONG THE VIRGINIA AND WEST VIRGINIA BORDERS WILL LIKELY SEE MOSTLY SNOW THROUGHOUT THE DAY ON TUESDAY AND TUESDAY NIGHT. LITTLE IF ANY SNOW ACCUMULATION IS EXPECTED OVERALL...BUT A LIGHT DUSTING COULD OCCUR ALONG THE HIGHEST RIDGE TOPS NEAR THE VIRGINIA AND WEST VIRGINIA BORDERS. ALSO DECIDED TO INCREASE PRECIP CHANCES A BIT FOR MONDAY AND MONDAY AFTERNOON...AS THE MODELS ARE SHOWING GOOD MID AND UPPER LEVEL JET INTERACTION ACROSS THE OHIO VALLEY DURING THE DAY ON MONDAY. THE 12Z GFS MODEL SOUNDINGS DID SHOW SOME INDICATIONS OF POTENTIAL FREEZING RAIN FOR EARLY MONDAY MORNING...BUT THIS WAS QUITE A CHANGE FROM THE 6Z RUNS AND WITH THE AMOUNT OF UNCERTAINTY REGARDING THIS...WILL HOLD OFF ON MENTION OF ANY FROZEN PRECIP FOR NOW...INSTEAD GOING WITH SNOW OR A RAIN SNOW MIX. MOIST NORTHWEST FLOW BEHIND THE DEPARTING UPPER LOW WILL BE THE IMPETUS FOR CONTINUED SCATTERED LIGHT RAIN AND SHOW SHOWERS TUESDAY NIGHT THROUGH WEDNESDAY AFTERNOON...WITH A TYPICAL UPSLOPE PATTERN SETTING UP. WITH STRONG HIGH PRESSURE BUILDING ACROSS THE AREA OVER THE WEEKEND...DECIDED TO DECREASE CLOUD COVER A BIT AS WELL. MODEL SOUNDINGS AND TIME HEIGHT CROSS SECTIONS ALSO SUPPORTED THIS. SKY COVER FORECAST FOR MONDAY THROUGH WEDNESDAY WAS LEFT ESSENTIALLY THE SAME AS BEFORE...WITH THE PRIMARY LONG RANGE MODELS IN GOOD AGREEMENT WITH THE TIMING OF THE NEXT WEATHER MAKER FOR ALL THREE DAYS. THE MODEL DATA SUPPORT SLIGHTLY COOLER TEMPERATURES FOR SATURDAY AND SUNDAY THAN THE MOS DATA REFLECTS...SO WENT A BIT COOLER FOR HIGHS ON SATURDAY AND SUNDAY. TEMPERATURES ON MONDAY...TUESDAY...AND WEDNESDAY WILL BE COOLER THAN THE LATEST MOS NUMBERS DUE TO THE EXPECTED CLOUD COVER AND PRECIPITATION...THEREFORE...ADJUSTMENTS WERE MADE TO ACCOUNT FOR THESE FACTORS. OVERNIGHT LOW TEMPERATURES WILL STAY FAIRLY STEADY ON EACH NIGHT THAT HAS LOTS OF CLOUD COVER. THE HPC GUIDANCE WAS FAVORED HERE...SO WENT SLIGHTLY WARMER THAN HPC MOS ACROSS THE BOARD FOR OVERNIGHT LOWS THROUGH TUESDAY NIGHT. DEWPOINTS AND WINDS WERE ALSO TWEAKED SLIGHTLY. THE DEWPOINTS APPEARED TO BE A BIT TOO HIGH COMPARED TO THE LATEST SURFACE OBS AND THE LAST TWO RUNS OF MEXMOS...AS A RESULT...DEW POINTS WERE DECREASED A BIT FOR THE MAJORITY OF THE EXTENDED FORECAST PERIOD. WINDS WERE ALSO ADJUSTED SLIGHTLY TO ACCOUNT FOR THE MINOR CHANGES MADE TO THE TIMING OF THE FRONTAL PASSAGE ON MONDAY AND MONDAY NIGHT. && .AVIATION.../00Z TO 24Z/...UPDATED A COLD FRONT EXTENDING SOUTH FROM AN AREA OF LOW PRESSURE OVER THE NORTHERN GREAT LAKES WILL MOVE SOUTHEAST INTO THE OH VALLEY EARLY IN THE PERIOD AND THEN INTO THE APPALACHIANS AROUND 12Z. ALTHOUGH THERE ARE NOT MANY LOW CLOUDS AHEAD OF THE BOUNDARY...MODELS INDICATE SOME MOISTURE ADVECTION OVERNIGHT. NAM AND GFS DATA BOTH INDICATE SOME SATURATION IN THE MVFR RANGE CLOSE TO THE BOUNDARY FOR A COUPLE OF HOURS AROUND 9Z AS WELL AS IN THE MID CLOUD RANGE. STAYED CLOSE TO THE PREVIOUS FORECAST...WITH THIS...THOUGH SHORTENED THE LENGTH OF MVFR TO ABOUT 3 TO 4 HOURS CENTERED AROUND 9Z...MORE IN LINE WITH THE DRIER NAM AND RUC. LOW LEVEL DRYING SHOULD THEN OCCUR AS THE SFC HIGH BUILDS IN...THOUGH SOME STRATOCU AND CU SHOULD OCCUR THROUGH THE END OF THE PERIOD JUST BELOW THE SUBSIDENCE INVERSION. WINDS WILL ALSO SHIFT TO NW TO NWW BY 16Z BEHIND THE FRONT. && .JKL WATCHES/WARNINGS/ADVISORIES...NONE. && $$ SHORT TERM...HAL LONG TERM....AR AVIATION...JP ky AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LAKE CHARLES LA 812 PM CST THU NOV 20 2008 .UPDATE...THE STRONG CANADIAN COLD FRONT IS TRACKING RAPIDLY SOUTHWARD THROUGH THE LAKES AREA OF SOUTHEST TEXAS AND CENTRAL LOUISIANA. MOVEMENT IS SOUTH AT 20 MPH. BOTH THE FORT POLK AND LAKE CHARLES RADARS SHOW THIS BOUNDARY WELL. AT THE CURRENT SPEED, THE COLD FRONT SHOULD REACH THE COAST BY 11 PM. WILL HOLD OFF ON ANY LAKE WIND ADVISORIES PER LATEST MAV GUIDANCE AND FORT POLK VAD WINDS BUT HAVE LOWERED EXPECTED MORNING TEMPERATURES TO AROUND 40 DEGREES FOR THE I-10 CORRIDOR AND THE MID 30S ACROSS THE NORTHERN TIER. THIS IS IN RESPONSE TO UPSTREAM DEW POINTS BEHIND THE FRONT THIS AFTERNOON RANGING FROM 26 TO 34 DEGREES. GUIDANCE WILL TYPICALLY OVERSHOOT TEMPERATURES ON AIRMASSES SUCH AS THIS ONE WITH ARCTIC ORIGINS. FORTUNATELY, THE ARCTIC AIR WILL REMAIN POISED NORTH OF THE OHIO VALLEY AND THE COLD DOME OF HIGH PRESSURE WILL DOMINATE THE TENNESSEE VALLEY THIS WEEKEND. && .MARINE...THE LATEST RUC AND NAM GUIDANCE GIVES SUSTAINED 30 KNOTS UNDER STRONG COLD ADVECTION TO THE WATERS. FELT IT PRUDENT TO GO WITH A GALE WARNING FOR FREQUENT GUSTS TO 35 KNOTS DURING THE PEAK HOURS FOR WINDS BETWEEN 3 AM AND 8 AM. THE REMAINING SMALL CRAFT ADVISORIES LOOK GOOD. && .PREV DISCUSSION... /ISSUED 541 PM CST THU NOV 20 2008/ AVIATION... COLD FRONT CONTINUES TO PUSH SOUTHEAST TOWARD THE AREA...LOCATED JUST NORTH OF THE LAKES AREA OF EAST TEXAS TO CENTRAL LA. FRONT TO PASS ACROSS KAEX BY 01Z...REACHING THE SOUTHERN TAF SITES BY 03Z. WINDS WILL SHIFT NORTH AND INCREASE WITH THE FROPA. WINDS EXPECTED TO INCREASE TO BETWEEN 15 AND 20 KNOTS WITH GUSTS TO AROUND 25 KNOTS BY MIDNIGHT...ESPECIALLY ACROSS SOUTHERN AREAS. COULD ALSO SEE SOME CLOUDS ALONG AND BEHIND THE FRONT...WITH A BRIEF PERIOD OF BKN CIGS AROUND 4000 FT. SKIES WILL CLEAR BY SUNRISE BUT WINDS WILL BE SLOW TO SUBSIDE THROUGH TOMORROW AFTERNOON. 24 PREV DISCUSSION... /ISSUED 423 PM CST THU NOV 20 2008/ (FCSTR 13) DISCUSSION... COLD FRONT CURRENTLY NEAR A SHREVEPORT TO COLLEGE STATION LINE AND MAKING GOOD SOUTHEAST PROGRESS. BOUNDARY EXPECTED TO HAVE CLEARED THE CWA BY MIDNIGHT...CONTINUING TO PROGRESS THROUGH THE COASTAL WATERS THEREAFTER. MUCH COOLER AND DRIER AIR WILL FILTER IN BEHIND THE FRONT...WITH GUSTY NORTH WINDS EXPECTED TO DEVELOP AS THE FRONT PASSES. WINDS WILL BE NEAR LAKE WIND ADVISORY CRITERIA...BUT THE SETUP IS NOT AS FAVORABLE HERE WITH THE H925 AND SFC WINDS NOT QUITE AS WELL ALIGNED AS THEY ARE FARTHER TO THE NORTH. FRONTAL PASSAGE CONTINUES TO LOOK LARGELY DRY...AND HAVE HELD ONTO JUST THE SLIGHT CHANCE OF -RW OVER THE COASTAL WATERS TONIGHT. OTHERWISE...MAINLY JUST CLOUD COVER TO CONTEND WITH. AMID STRONG CAA REGIME...UNDERCUT GUIDANCE ACROSS THE BOARD AS TEMPERATURES TOMORROW WILL STRUGGLE TO REACH THE MID 50S. TOMORROW NIGHT WILL BE THE COLDEST OF THIS SEVEN DAY FORECAST...AND GIVEN THE BONE DRY AIR SHOWN BY THE MODELS...AGAIN WILL CUT UNDER GUIDANCE NUMBERS. THIS RESULTS IN FREEZING TEMPERATURES FOR MOST OF THE AREA ALONG AND NORTH OF I-10...AND A HARD FREEZE OVER PARTS OF CENTRAL LOUISIANA. CONSIDERED A FREEZE WATCH PRODUCT TO ADVERTISE THIS...BUT WOULD PREFER TO BE DONE WITH THE HAZARDS ASSOCIATED WITH THE IMMEDIATE FRONTAL. WILL HIGHLIGHT IN THE HWO INSTEAD. THIS AIRMASS WILL BE SHORT LIVED AS THE GFS AND ECMWF CONTINUE TO DEPICT A WARM/MOIST AIR REGIME SETTING UP BY SATURDAY NIGHT...AND CONTINUING INTO MONDAY AHEAD OF YET ANOTHER FRONT. CURRENT FORECAST OF SLIGHT CHANCE TO LOW END CHANCE POPS CONTINUES TO LOOK SUFFICIENT AT THIS TIME. FORECAST FOR MID TO LATE PART OF THE WEEK WAS A BLEND OF THE 06Z GFS AND TWO LATEST ECMWF RUNS...WHICH HAVE TEMPERED THE COOLDOWN BEHIND THE FRONT MONDAY...AND THEREAFTER SHOW A WARNING TREND UNDER WEAK RIDGING ALOFT. MARINE... A STRONG COLD FRONT WILL PUSH THROUGH THE COASTAL WATERS OVERNIGHT TONIGHT...WITH GUSTY OFFSHORE WINDS AND ROUGH SEAS EXPECTED THROUGH FRIDAY AFTERNOON. SMALL CRAFT ADVISORIES REMAIN IN PLACE. WINDS AND SEAS WILL REMAIN MODERATE AS ONSHORE FLOW RETURNS BY THE END OF THE WEEKEND...WITH AN INCREASING CHANCE OF RAIN EARLY NEXT WEEK. && .PRELIMINARY POINT TEMPS/POPS... KLCH 40 54 32 61 49 / 5 0 0 0 10 KBPT 40 54 35 61 51 / 5 0 0 0 10 KAEX 34 51 27 58 41 / 5 0 0 0 10 KLFT 40 53 30 61 46 / 5 0 0 0 10 && .LCH WATCHES/WARNINGS/ADVISORIES... LA...NONE. TX...NONE. GM...GALE WARNING FROM 3 AM TO 8 AM FOR THE COASTAL WATERS OUT TO 60 NM. SMALL CRAFT ADVISORY FROM MIDNIGHT TONIGHT TO 6 PM CST FRIDAY FOR THE FOLLOWING ZONES: WATERS FROM CAMERON, LA TO HIGH ISLAND, TX EXTENDING FROM 20 NM TO 60 NM ...WATERS FROM INTRACOASTAL CITY, LA TO CAMERON, LA EXTENDING FROM 20 NM TO 60 NM...WATERS FROM LOWER ATCHAFALAYA RIVER TO INTRACOASTAL CITY, LA EXTENDING FROM 20 NM TO 60 NM. SMALL CRAFT ADVISORY FROM MIDNIGHT TONIGHT TO 12 PM CST FRIDAY FOR THE FOLLOWING ZONES: CALCASIEU LAKE...SABINE LAKE... VERMILION BAY. SMALL CRAFT ADVISORY FROM MIDNIGHT TONIGHT TO 3 PM CST FRIDAY FOR THE FOLLOWING ZONES: COASTAL WATERS FROM CAMERON, LA TO HIGH ISLAND, TX OUT 20 NM...COASTAL WATERS FROM INTRACOASTAL CITY TO CAMERON, LA OUT 20 NM...COASTAL WATERS FROM LOWER ATCHAFALAYA RIVER TO INTRACOASTAL CITY, LA OUT 20 NM. && $$ SWEENEY la AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WAKEFIELD VA 956 PM EST THU NOV 20 2008 .SYNOPSIS... WEAK LOW PRESSURE WILL MOVE ACROSS THE REGION TONIGHT THROUGH FRIDAY. CANADIAN HIGH PRESSURE BUILDS INTO THE AREA FROM THE WEST SATURDAY THROUGH SUNDAY. && .NEAR TERM /UNTIL 6 AM FRIDAY MORNING/... MID LVL CLOUD DECK (BTWN 7K-11K FT) QUICKLY OVRSPRDG FA THIS EVE IN RESPONSE TO UPR LVL TROF APPRCHG RGN. ONLY LIMITED MSTR PROGGED WITH THIS FTR AFTR 08Z TONITE AS LWR LVLS REMAIN DRY. DESPITE THIS DRY AIR...LTST RUC/SREF AND TO SOME DEGREE THE NAM PRODUCES AN AREA OF LGT MSTR ACROSS SRN HALF OF FA. THUS...HAVE EXPANDED THE AREA OF FLURRIES GNRLY S OF I64...ALTHOUGH VIRGA IS MORE LIKELY TO OCCUR. GIVEN THE CLOUD COVER...BUMPED UP TMPS A FEW DEGREES ACROSS WRN CNTYS. && .SHORT TERM /6 AM FRIDAY MORNING THROUGH SUNDAY/... TROF AXIS MOVES TO THE E EARLY FRI WITH CHANCE OF PRECIP DIMINISHING OVER SRN COUNTIES. NW FETCH STRENGTHENS OVER THE CHES BAY DURING THE DAY FRI AND MODELS CONTINUE TO DEVELOP BAY EFFECT PRECIP PLUMES OVER THE LWR MD/VA ERN SHORE...AND HAVE INCLUDED A SLIGHT CHANCE OF -RA OR -SN FOR THOSE AREAS. HIGH TEMPS COOLER AND WELL BELOW NORMAL ON FRI WITH H5 TROF SETTLING IN...ONLY 40 TO 45. SAT/SUN LOOK QUIET AS SFC HIGH PRES BUILDS OVR THE REGION FROM THE W. HIGHS IN THE 40S SAT THEN SLIGHTLY WARMER UPR 40S TO LWR 50S SUN...WITH LOWS NEAR 20 TO 34 SAT NIGHT...AND UPR 20S TO UPR 30S SUN NIGHT. && .LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/... THE HIGH SHIFTS OFFSHORE SUNDAY NIGHT SO EXPECTING AN INCREASE IN OVERNIGHT LOWS THAT NIGHT/MONDAY MORNING. FREEZING TEMPS WILL CONTINUE INLAND BUT SHOULD BE JUST ABOVE FREEZING CLOSER TO THE COAST. ON MONDAY AN UPR LOW DIVES DOWN INTO THE GREAT LAKES REGION FROM THE NORTH AND A FRONT SHIFTS OUR DIRECTION DURING THE MID TO LATE AFTN HRS. MODELS NOW IN SOMEWHAT BETTER AGREEMENT ON TIMING...SO HAVE BUMPED UP POPS SLIGHTLY DURING THE AFTN HRS AND CONTINUE THEM INTO THE OVERNIGHT HRS AS THE FRONT SHOULD PUSH OFFSHORE IN THE EARLY MORNING HRS ON TUESDAY. SOME QUESTION AS TO WHETHER WE SEE ANY SNOW EARLY TUES MORNING WITH THE REMAINING MOISTURE RIGHT BEHIND THE FRONT. FOR NOW...THINK THAT TEMPS WILL BE JUST ABOVE FREEZING INLAND (MODELS ARE COMING IN SLIGHTLY WARMER THAN PREVIOUS RUNS)...BUT CAN`T RULE OUT A FEW FLAKES WHERE IT MANAGES TO GET COLDER QUICKLY. THE LOW PULLS UP TO THE NORTH ON TUESDAY AS A HIGH PUSHES IN FROM THE CNTRL PLAINS...SO ALTHOUGH COLDER TEMPS EXPECTED ON WED...NOT TOO MUCH BLO FREEZING FOR MINS ON WED AND THURS MORNINGS. THE HIGH REMAINS OVER THE SOUTHEAST U.S. THROUGH THURS MORNING THEN PUSHES OFFSHORE DURING THE DAYTIME HRS. && .AVIATION /03Z FRIDAY THROUGH TUESDAY/... VFR CONDITIONS COVER THE TAF SITES THIS EVENING AND THIS WILL CONTINUE OVERNIGHT. SATELLITE AND BUFR SOUNDINGS INDICATE SCT CLOUDS AT AROUND 7 THOUSAND FEET. SKIES WILL VARY FROM CLEAR TO BROKEN CLOUD COVER BUT SAW NO REASON TO TIME SUCH CHANGES IN THE TAF. NW WINDS WILL INCREASE ON FRI AS WELL AS STRONG COLD AIR ADVECTION. MODEL SOUNDINGS INDICATE CEILINGS OF AROUND 5 TO 6 THOUSAND FEET DURING THE DAY EXCEPT AS LOW AS 4 THOUSAND AT SBY WHERE THERE WILL BE A CHANCE OF SNOW SHOWERS. INCLUDED VCSH THERE AFT 15Z. HIGH PRESSURE WILL SLOWLY BUILD INTO THE AREA THROUGH THE WEEKEND. VFR WILL CONTINUE THROUGH MONDAY. THE NEXT COLD FRONT IS EXPECTED TO MOVE THROUGH LATE MON OR EARLY TUE WHEN THERE MAY BE A FEW RAIN SHOWERS. && .MARINE... WINDS OVER THE LOWER BAY AND OFF THE SE VA AND NC COAST HAVE BEEN NORTHERLY THIS EVENING...PERHAPS IN RESPONSE TO A SURFACE LOW PRESSURE AREA THAT IS OVER SC. THE RUC IS THE ONLY MODEL THAT IS HANDLING THIS WIND AND USED IT FOR THE SURFACE WIND DIRECTION IN THE GRIDS OVERNIGHT. WINDS OVER THE BAY ARE CURRENTLY IN SCA RANGE...AND THIS SHOULD CONTINUE THROUGH MOST OF THE OVERNIGHT. WITH THE EXPECTED COLD SURGE FRIDAY...EXPECTING WINDS OVER ALL THE WATERS TO INCREASE AROUND EARLY TO MID MORNING. SCA CONDS OFFSHORE WILL QUICKLY INCREASE TO GALE (OR AT LEAST FREQUENT GUSTS) BY LATE MORNING. HIGH PRESSURE SHIFTS TOWARDS THE MID ATLANTIC REGION SAT MORNING WHICH WILL HELP TO SUBSIDE WINDS...BUT SCA CONDS CONTINUE THROUGH MUCH OF THE DAY WITH CONTINUED COLD AIR OVER THE AREA. THE HIGH MVS OFFSHORE ON SUNDAY SO WINDS SHIFT BACK AROUND TO THE SOUTH...AND BEGIN TO INCREASE AGAIN ON MON AFTN AS A FRONT APPROACHES. && .AKQ WATCHES/WARNINGS/ADVISORIES... MD...NONE. NC...NONE. VA...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 6 PM EST SATURDAY FOR ANZ630>632. SMALL CRAFT ADVISORY FROM 10 AM FRIDAY TO 6 PM EST SATURDAY FOR ANZ633. SMALL CRAFT ADVISORY FROM 10 AM TO 4 PM EST FRIDAY FOR ANZ650- 652-654-656-658. GALE WARNING FROM 4 PM FRIDAY TO 1 AM EST SATURDAY FOR ANZ650- 652-654-656-658. && $$ SYNOPSIS...JRL NEAR TERM...JRL/MPR SHORT TERM...JRL LONG TERM...JYM AVIATION...LSA MARINE...JYM/LSA md AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WAKEFIELD VA 1029 AM EST WED NOV 19 2008 .SYNOPSIS... HIGH PRESSURE WILL BUILD FROM THE MID MISSISSIPPI RIVER VALLEY TO THE MID ATLANTIC REGION THROUGH WEDNESDAY. A COLD FRONT WILL PUSH THROUGH THE AREA LATE THURSDAY...FOLLOWED BY ANOTHER PERIOD OF UNSEASONABLY COLD WEATHER FRIDAY INTO THE WEEKEND. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... LOOKING AT UPPER AIR SOUNDINGS AND CURRENT RUC WILL LOWER MAX TEMPS SEVERAL DEGREES. UPR TROF MVS OFFSHORE THIS MORNING...AND MORE TRANQUIL (BUT STILL VERY COLD) WX FOLLOWS AS SFC HIGH PRES BUILDS OVR THE SE STATES. HIGHS TODAY NOT UNLIKE TUE...BUT IT MAY FEEL A TAD WARMER AS WINDS WILL NOT BE NEARLY AS GUSTY AS TUE. HIGHS 40-45. && .SHORT TERM /6 PM THIS EVENING THROUGH FRIDAY/... YET ANOTHER COLD NIGHT TONIGHT...THOUGH WITH MUCH LIGHTER WINDS. EVEN COASTAL LOCATIONS SUCH AS VA BEACH/ORF WILL GET DOWN TO BLW FREEZING TEMPS...AND MAY REQUIRE A FREEZE WARNINGS TO OFFICALLY END THE GROWING SEASON. LOW TEMPS WIDESPREAD 20-30 ACROSS THE CWA. TEMPS MODERATE (SOMEWHAT) ON THU UNDER WESTERLY FLOW...AND AGREE WITH PREV FORECAST ASSESEMENT THAT COOLING FROM CD FROPA THU AFTN WON`T COME TILL THE EVENING. HIGHS GENERALLY 50-55. NEXT BLAST OF COLD AIR ARRIVES OVERNIGHT THU INTO FRI..AS UPF TROF AMPLIFIES AND TEMPS RETURN TO HIGHS IN THE 40S...SIMILAR TO TUE/WED. INTENSIFICATION OF THIS TROF MAY LEAD TO A FEW FLURRIES OR SPRIKLES ACROSS THE ERN SHORE EARLY FRI...BEFORE POSSIBLY DEVLOPING INTO A BAY EFFECT PLUME LATE FRI AFTN THRU THE EVENING. CURRENTLY INCLUDED CHC OF FLURRIES OR SPRINKLES ACROSS THE ERN SHORE FRI AFTN...THEN A CHC OF FLURRIES FOR THE BAY EFFECT PLUME BY FRI EVENING. HI TEMPS LOW TO MID 40S. && .LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/... MDLS IN GEN AGREEMENT WITH LOW PRES STRENGTHENING OFF THE MID-ATLANTIC COAST AS STRONG HIGH PRESSURE BEGINS TO BUILD IN FROM THE WEST FRIDAY INTO SATURDAY. PRES GRAD WILL AGAIN BRING BREEZY CONDS AT LEAST FOR THE FIRST PART OF THE WEEKEND BEFORE TAPERING LATE SATURDAY INTO SUN MORNING. HIGH PRESSURE IS PROGGED TO BE ANCHORED IN FOR THE REMAINDER OF THE WEEKEND INTO TUESDAY FOR NOW. LOOKS TO BE A MOSTLY DRY PERIOD WITH HIGH TEMPS GENERALLY IN THE 40S BEFORE MODERATING SOMEWHAT INTO THE 50S BY SUNDAY. LOW TEMPS WILL LIKELY BE IN THE M/U 30S...40S ON SUNDAY. && .AVIATION /16Z WEDNESDAY THROUGH SUNDAY/... BANDS OF SNOW SHOWERS CONTINUE DUE TO BAY EFFECT ACROSS THE LOWER EASTERN SHORE OF VIRGINIA AND SSE INTO THE ATLANTIC...JUST GLANCING KNTU AT TIMES. THE BANDS ARE EXPECTED TO BECOME MORE N-S ORIENTED AS THE HIGH BUILDS CLOSER TO THE REGION (MEAN LLVL FLOW TO BECOME MORE ANTI-CYCLONIC OR NORTHERLY VS. NW). THIS SHOULD BRING THE MORE EXTENSIVE BAY-EFFECT CLOUD COVER INTO KORF AND KNTU (VFR BASES AOA 4KFT). AT THE SAME TIME...THE TRADEOFF WILL BE WITH THE LOWERING INVERSION HEIGHTS/CBL AS THE SUBSIDENCE STRENGTHENS...THUS EXPECT MORE FLURRIES THAN SNOW SHOWERS (I.E. VSBYS MAINLY VFR OR 6+ SM) TOWARD DAYBREAK AS THESE BANDS DRIFT FARTHER INLAND ACROSS THE TIDEWATER REGION. THIS AFTN...THE CORE OF THE COLD AIR ALOFT WILL BE EAST OF OUR AREA SO THERE WILL NOT BE A REPEAT OF THE CONVECTIVE SNOW SHOWERS. HIGH PRESSURE CONTINUES TO BUILD INTO THE MID ATLC REGION FROM THE W... HOWEVER WITH THE OFFSHORE LOW CONTINUING TO INTENSIFY/DEEPEN... EXPECT 15-20+ NW FLOW TO CONTINUE ACROSS ERN VA/NC AND ESPECIALLY OVER THE LWR MD/VA ERN SHORE. VFR AND DRY CONDITIONS WILL GENERALLY CONTINUE THE REST OF THE WEEK. ANOTHER COLD FRONT WILL AFFECT THE AREA LATE THU AND FRI...HOWEVER LITTLE IN THE WAY OF PRECIPITATION IS EXPECTED WITH THE DEEP NW (DOWNSLOPE) FLOW THROUGH THE LOW LEVELS. && .MARINE... WINDS/WAVES WILL CONTINUE TO SUBSIDE LATE THIS AM AND THROUGH THE AFTN. DROPPED GALE WRNGS FOR THE CSTL WTRS AND PUT UP SCA UNTIL 12Z THU. SCA CONT FOR THE CHES BAY AND CURRITUCK SND UNTIL 6 PM THIS EVENING. MODELS INDICATE ANOTHER SURGE OF COLD AIR AND SUBSEQUENT GALE OR STRONG SCA POSSIBLE FRI INTO SATURDAY. && .CLIMATE... LAST TIME MEASURABLE SNOWFALL OCCURRED IN NOVEMBER: RICHMOND....1991/8TH (0.1") NORFOLK.....1987/11TH (0.3") SALISBURY...1989/22-23RD (2.5") RCRD LO TEMPS: NOV 19 RIC 18 1936 ORF 25 1959 SBY 17 1936 ECG 21 1959 NOV 20 RIC 21 1951 ORF 27 1980 SBY 22 1924 ECG 25 1997 && .AKQ WATCHES/WARNINGS/ADVISORIES... MD...NONE. NC...NONE. VA...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 6 PM EST THIS AFTERNOON FOR ANZ630>633. SMALL CRAFT ADVISORY UNTIL 7 AM EST THURSDAY FOR ANZ650-652- 654-656-658. && $$ SYNOPSIS...SMF NEAR TERM...JAB/SMF SHORT TERM...SMF LONG TERM...KLL AVIATION...BKH MARINE...JEF CLIMATE... md AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE MARQUETTE MI 1010 PM EST THU NOV 20 2008 .UPDATE... WEAK SHORTWAVE PUSHING ACROSS THE AREA THIS EVENING LED TO AN INCREASE IN THE LK EFFECT OVER WRN CWA...ESPECIALLY FM HIGHER TERRAIN OF ONTONAGON COUNTY INTO BARAGA COUNTY. IR SATELLITE INDICATES ENHANCEMENT IS BEGINNING TO DIMINISH THOUGH. HEAVY LK EFFECT OVR CNTRL COUNTIES PRETTY MUCH STAYED STEADY STATE WHILE THIS SHORTWAVE MOVED THROUGH. POUNDING CONTINUES OVR NW QUARTER OF DELTA COUNTY...WITH STORM TOTALS FM ROCK TO CORNELL TO NEAR GLADSTONE WELL OVR A FOOT. WINDS HAVE GRADUALLY BACKED THIS EVENING AS SHORTWAVE PASSED THROUGH AND THIS RESULTED IN HEAVIEST SNOW SHIFTING TO THE EAST OF MARQUETTE COUNTY WITH ALGER INTO SCHOOLCRAFT AND WRN LUCE NOW IN THE HEAVIER SNOW SHOWERS AND SQUALLS. AM GOING TO LEAVE CURRENT HEADLINES ALONE. THOUGHT ABOUT DROPPING MARQUETTE AS OVERALL SCOPE OF SNOW SHOWERS HAS DIMINISHED CONSIDERABLY. HOWEVER...CONSIDERING ISOLATED HEAVIER SNOW SHOWERS STILL EXIST OVR THE WRN SECTIONS OF MARQUETTE INTO BARAGA WILL STILL HAVE TO PUSH ACROSS THROUGH THE NIGHT...ALONG WITH GUSTY NW WINDS AND BLSN...KEPT THE WARNING GOING. ADDITIONAL SNOW AMOUNTS SHOULD NOT GET TOO OUT OF HAND THOUGH FOR MARQUETTE COUNTY AS BANDS WILL REMAIN ON THE MOVE. WARNINGS IN THE EAST SHOULD WORK OUT FINE. DID TWEAK SNOW AMOUNTS DOWN IN LUCE COUNTY TIL AFTER MIDNIGHT ONCE LOW LEVEL WINDS BACK MORE TO THE NW. OTHERWISE...PARTIAL LK NIPEGON CONNECTION TO THE SNOW SHOWERS AND STRONG WINDS WILL CONTINUE TO PROPEL STRONGER SNOW SHOWERS ALL THE WAY TOWARD THE LK MICHIGAN SHORELINE. WINDS BACKING NW WILL FINALLY END THE HIGHLY UNUSUAL HEAVY LK SUPERIOR LK EFFECT EVENT OVR WRN DELTA COUNTY. && .SYNOPSIS... 12Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW COLD NNW FLOW (12Z H85 TEMPS RANGE FM -18C AT YPL TO -14C AT GRB) OVER THE RELATIVELY WARM WATERS OF LK SUP (WATER TEMPS RANGE FM 5C OVER THE W TO 8C IN THE E) BTWN ARCTIC HI PRES OVER SCNTRL CAN AND LO PRES IN SE CAN. NMRS LES BANDS ARE EVIDENT OVER MAINLY THE E HALF OF THE LK. A LOOK AT 12Z RAOBS SEEMS TO INDICATE WHY THE LES IS HEAVIEST OVER THIS PORTION OF THE LK. SHALLOW CLDS OVER WRN LK SUP IS WHERE STABILITY IS HIER/AIRMASS DRIER PER 12Z INL RAOB...WHICH SHOWS INVRN BASE AT H9 UNDER BONE DRY MID LVLS. ALTHOUGH 12Z YPL RAOB INDICATES INVRN BASE NEAR H9 AS WELL...THAT SDNG SHOWS MSTR THRU H7. SO LES BANDS OVER THE E HALF OF THE LK ARE MUCH MORE WELL DVLPD...ESPECIALLY THE BAND FED BY APRNT MOISTENING OFF LK NIPIGON. 16Z TAMDAR SDNG FM SAW SHOWS INVRN BASE ARND H85...BUT TEMPS WITHIN THE MIXED LYR ARE IN THE -10C TO -17C RANGE AND QUITE FVRBL FOR DENDRITIC SN GROWTH. SO SN IS OF A VERY FLUFFY NATURE WITH HIER SN/WATER RATIOS. THE BANDS HAVE WEAKENED SOMEWHAT DURING THE DAY WITH DAYTIME HTG DIMINISHING THE SHARPER LAND BREEZE CNVGC THAT ACCOMPANIES A WSHFT TO MORE NW OVER LAND DURING NOCTURNAL COOLING. OTRW...A SHRTWV APPEARS TO BE DIGGING SWD THRU ONTARIO ARND CLOSED LO NEAR JAMES BAY. && .SHORT TERM DISCUSSION (TONIGHT AND FRI)... MAIN FCST CONCERNS ARE LES TRENDS/AMTS/GOING HEADLINES. FOR TNGT...SHRTWV OVER ONTARIO PROGGED TO SWING SEWD ACRS THE ERN ZNS AND TO NE LK HURON BY 12Z FRI. LLVL WINDS ARE PROGGED TO BACK MORE NW THRU THE NGT IN RESPONSE TO THIS TRACK. THIS SHRTWV MOTION WL SUPPORT HIER INVRN BASE/DEEPER MOIST LYR OVER THE ERN CWA (DOWNWIND OF YPL)...WITH LOWER INVRN HGT LIKELY OVER THE W UNDER HIER HGTS (DOWNWIND OF INL). H85 TEMPS PROGGED TO FALL A DEGREE OR TWO DURING THE NGT...SO THERMAL PROFILE WITHIN MIXED LYR WL REMAIN FVRBL FOR HIER SN/WATER RATIOS. SO...LARGER SCALE FACTORS FAVOR A CONTINUATION OF HEAVY LES OVER THE E WITH LESSER INTENSITY OVER THE W. MOST LIKELY FOCUS FOR REALLY HEFTY AMTS WL BE INITIALLY OVER THE CNTRL FM MQT-ESC...WHERE HIER RES LOCAL WRF-ARW/RUC13 MODELS HINT AT SHARPEST H925 CNVGC THRU 03Z. AS THE LARGER SCALE WINDS BACK MORE NW...THE MORE FVRBL LLVL CNVGC WL DRIFT TO THE E. DVLPMNT OF LAND BREEZE OFF THE WCNTRL HIER TERRAIN...WHERE TEMPS WL BE LOWEST TNGT...WL TEND TO REINFORCE THE INTENSITY OF THE WRN-MOST BAND. MOISTENING OFF LK NIPIGON WL CONT TO ENHANCE THIS BAND AS WELL. HINT OF LAND BREEZE OFF ONTARIO... MORE VEERED WIND OVER THE ERN U.P... MIGHT HAVE THE SAME IMPACT IN LUCE COUNTY. ON FRI...ANOTHER SHEARED OUT SHRTWV WL APRCH FM THE NW AND PASS OVER THE ERN COUNTIES DURING THE DAY. AS WL BE THE CASE TNGT...INVRN HGT/ DEPTH OF MOIST LYR WL REMAIN HI OVER THE E ON THE CYC TRACK OF THIS SHRTWV TRACK BUT QUITE A BIT LOWER OVER THE W. EXPECT THE HEAVIEST LES OVER THE E UNDER THIS HIER INVRN WITH LLVL FLOW ALSO SLOWLY BACKING MORE NW. 12Z NAM/RUC13/WRF-ARW HINT AT SHARP LLVL CNVGC OVER LUCE/ERN ALGER/SCHOOLCRAFT COUNTIES...SO GOING WRNGS THERE LOOK ON TRACK EVEN IF LAND BREEZE CNVGC FADES A BIT THRU THE DAY. OVERALL... GOING ADVYS/ HEADLINES SEEM APPROPRIATE. ONLY PSBL UPDATE TO HEADLINES MAY BE NECESSITY OF WRNG FOR SRN SCHOOLCRAFT COUNTY AND ABILITY TO CANX ADVY EARLY OVER THE W. COORDINATED WITH APX. .LONG TERM DISCUSSION (FRI NGT THRU THU)... DEPARTING MID LEVEL SHORTWAVE EXITS EASTERN CWA OVERNIGHT FRIDAY. EXPECT SOME LES TO LINGER ACROSS EASTERN ALGER AND LUCE COUNTIES THROUGH SUNRISE AS PROGGED NAM/GFS 925-850 DEWPOINT DP REMAIN LESS THAN 7 THROUGH THE AFTERNOON. WINDS LOOK TO TURN OFFSHORE BY 15Z...CUTTING OF LAKE EFFECT PROCESSES. HIGH PRESSURE WILL WORK ACROSS THE FA EARLY SATURDAY...AS THE HIGH SHIFT EAST OF LAKE SUPERIOR ON SATURDAY AFTN DRY SOUTHERLY FLOW KICKS IN. DID ADD IN SLIGHT CHANCE FOR FREEZING DRIZZLE BETWEEN 6Z AND 12Z SUNDAY AS LATEST BUFKIT PROFILES INDICATE SHALLOW MOISTURE BELOW 5KFT REMAINS WARMER THAN -10C ISOTHERM. .SUNDAY THROUGH TUESDAY MORNING...NEXT SYSTEM OF INTEREST WILL IMPACT THE FA SUNDAY NIGHT THROUGH LATE MONDAY. LOW PRESSURE IS PROGGED TO MOVE ACROSS THE NORTHERN CANADIAN PRAIRIES ON SUNDAY THEN DROP SOUTHEAST AND DEEPEN AS IT MOVES ACROSS THE UPPER GREAT LAKES ON MONDAY. LONG RANGE MODELS...ECMWF/GFS/GLBL-GEM...DISAGREE WITH OVERALL MOISTURE FIELDS...WHICH APPEARS MAINLY TO BE A FUNCTION OF THE UPSTREAM RIDGING. FLATTER 500MB RIDGE SUNDAY NIGHT IN ECMWF SOLUTION ALLOWS SYSTEM TO DROP FURTHER SOUTH. WHILE BOTH THE GFS AND GLBL-GEM HAVE MUCH BETTER DEFINED 500MB RIDGE EXTENDING BACK INTO HUDSON BAY. THE RESULT OF THIS MASS FIELD DIFFERENCE ALLOWS THE ECMWF LOW TO TRACK FURTHER SOUTH AND BE MORE PROGRESSIVE AND WEAKER...WHILE THE GFS/GLBL-GEM SOLUTIONS TRACK DIRECTLY OVER THE FCST AREA WITH A STRONGER/SLOWER PROGRESSION. AS FAR AS DETAILS GO...THIS TRANSLATES TO A HIGH IMPACT SYNOPTIC SNOW EVENT IN GFS WORLD AND A LOW IMPACT LES EVENT IN THE ECMWF SOLUTION. A QUICK LOOK AT SOME OF THE MASS FIELDS SHOWS MORE DIFFERENCES. LATEST ECMWF(12Z)...SHOWS GOOD MID LEVEL CONVERGENCE (PER 700-500MB DIVQ) THOUGH DEEP MOISTURE REMAINS EAST AND SOUTH OF THE FA. THE MORE BULLISH GFS SHOWS DEEP MOISTURE IS BETTER CO-LOCATED WITH BEST MID LEVEL CONVERGENCE FROM LATE SUNDAY NIGHT THROUGH MONDAY NIGHT AS THE LOW TRACKS DIRECTLY OVER THE U.P. FROM THEIR INITIALIZATION ITS HARD TO COME UP WITH ANY DIFFERENCE THAT WOULD LEAD TO THE VARYING SOLUTIONS. THUS HAVE MAINTAINED LOWER POPS THROUGHOUT. .TUESDAY MORNING THROUGH THURSDAY...TEMPORARY RIDGING WILL WORK ACROSS THE FA ON TUESDAY AND WEDNESDAY...ALLOWING TEMPERATURES TO TEMPORARILY WARM UP...THOUGH DON/T EXPECT TEMPERATURES TO QUITE REACH 40. TEMPERATURES ON THURSDAY ARE A VERY UNCERTAIN AT THIS POINT. 850MB TEMPS ARE AROUND -6 TO -8C IN THE GFS AND 0 TO +2C IN THE 12Z ECMWF SOLUTION...THIS DISCREPANCY IS DUE IN PART TO THE MODEL DIFFERENCES WITHIN THE PREVIOUS SYSTEM. THE NEXT SYSTEM BEGINS DIGGING INTO THE UPPER MISSISSIPPI VALLEY THURSDAY EVENING. BOTH THE GFS AND GLB-GEM AGREE WITH TIMING...THOUGH THERE ARE SIGNIFICANT STRENGTH DIFFERENCES. ECMWF SOLUTION KEEPS THIS SYSTEM OVER NORTHERN ONTARIO AND NORTH OF THE LAKES ALTOGETHER. && .AVIATION (FOR THE 00Z TAF ISSUANCE)... AT CMX...LK EFFECT SNOW BANDS WITH MVFR CIGS/VSBY THROUGH FRIDAY. HOWEVER...CONDITIONS MAY FALL TO IFR THIS EVENING AS MID LEVEL DISTURBANCE SHIFTS THROUGH AND ENHANCES THE SNOW. AT SAW...HEAVY LK EFFECT SNOW BAND HAS SHIFTED EAST OF SAW AS WINDS HAVE BACKED MORE NW. RESULT IS IMPROVING CONDITIONS OVR THOSE SEEN THE LAST 12 HRS. ALTHOUGH LK EFFECT WILL CONTINUE THROUGH LATE TONIGHT...CIGS AND VSBY WILL BE MORE IN THE MVFR RANGE. WINDS BECOMING WRLY SHOULD SHUT DOWN THE LK EFFECT AT SAW ON FRIDAY MORNING. && .MARINE (FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)... LOOK FOR LAKE SUPERIOR TO REMAIN SANDWICHED BETWEEN LOW PRESSURE OVER NEW ENGLAND AND HIGH PRESSURE BUILDING INTO THE NORTHERN PLAINS THROUGH FRIDAY AFTERNOON. AS A RESULT OF THIS STRONG PRESSURE GRADIENT...NORTH-NORTHWEST GALE FORCE WINDS TO 35 KNOTS ARE EXPECTED ACROSS NORTH CENTRAL AND EASTERN LAKES SUPERIOR THROUGH TONIGHT...WINDS WILL DIMINISH TO 30 KNOTS FRIDAY MORNING THROUGH FRIDAY AFTERNOON. NORTH-NORTHWEST WINDS WILL REACH NEAR GALE FORCE SUNDAY NIGHT INTO MONDAY ACROSS THE EAST HALF OF THE LAKE. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... LAKE EFFECT SNOW ADVISORY UNTIL 7 AM EST /6 AM CST/ FRIDAY FOR MIZ001>004-009-084. LAKE EFFECT SNOW WARNING UNTIL 10 PM EST FRIDAY FOR MIZ006-007- 085. LAKE EFFECT SNOW WARNING UNTIL 10 AM EST FRIDAY FOR MIZ005. LAKE EFFECT SNOW WARNING UNTIL 1 PM EST FRIDAY FOR MIZ013-014. LAKE SUPERIOR... GALE WARNING UNTIL 5 AM EST FRIDAY FOR LSZ266-267. GALE WARNING UNTIL 4 AM EST FRIDAY FOR LSZ265. GALE WARNING UNTIL 1 AM EST FRIDAY FOR LSZ243>245-264. GALE WARNING UNTIL 3 AM EST FRIDAY FOR LSZ249-250. LAKE MICHIGAN... NONE. && $$ UPDATE...JLA SYNOPSIS/SHORT TERM...KC LONG TERM...PEARSON AVIATION...JLA MARINE...PEARSON mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI 938 PM EST THU NOV 20 2008 .UPDATE... AS COVERAGE OF INLAND SNOW SHOWERS CONTINUES TO DIMINISH THIS EVENING, CONCERN FOR LAKE EFFECT SNOW REMAINS IN THE THUMB. SURFACE ANALYSES OVER THE LAST FEW HOURS SHOW THE WINDS STRONGLY BACKED TO THE NORTHWEST OVER WESTERN PORTIONS OF THE LAKE ALL THE WAY UP TO PRESQUE ISLE, AND THIS HAS KEPT ACTIVITY OFFSHORE FOR MUCH OF THE EVENING. HOWEVER, THE LATEST MODEL DATA IS NOT CONVINCING THAT THIS WILL LAST ALL NIGHT AND TEND TO AGREE AS THERE IS STILL AN OPPORTUNITY FOR THE LOW LEVEL WIND FIELD TO VEER AS A SHORT WAVE ROTATES THE REST OF THE WAY THROUGH LOWER MICHIGAN OVERNIGHT. AT THE SAME TIME, IT WILL TAKE A FEW MORE HOURS FOR THIS TO OCCUR, SO ANY ENCOUNTER WITH EASTERN SECTIONS OF HURON COUNTY WILL BE SHORTER IN DURATION BEFORE THE WINDS BACK MORE STRONGLY TO THE WEST TOWARD SUNRISE. FOR NOW, WE WILL DOWNGRADE TO AN ADVISORY TO ACCOUNT FOR THE ONGOING LENGTHY BREAK IN THE ACTION AND CALL FOR MORE OF A 3 TO 5 INCH ADDITIONAL ACCUMULATION DURING THE EARLY MORNING HOURS. && .PREV DISCUSSION...ISSUED 703 PM EST THU NOV 20 2008 AVIATION... SCATTERED SNOW SHOWERS ONGOING OVER SE MICHIGAN WILL DISSIPATE THIS EVENING AFTER DIMINISHING SUPPORT FROM THE LOW PRESSURE SYSTEM AND WITH THE LOSS OF DAYTIME HEATING. THIS WILL BE FOLLOWED BY A GRADUAL CLEARING TREND AS NW LOW LEVEL WIND FLOW PERSISTS. THIS IS A DRY FLOW FOR OUR AREA, ESPECIALLY AT NIGHT. VFR CONDITIONS WILL THEN CONTINUE THROUGH FRIDAY MORNING UNTIL CLOUDS INCREASE AGAIN BY AFTERNOON. ANOTHER ROUND OF SCATTERED SNOW SHOWERS IS EXPECTED DURING FRIDAY AFTERNOON THAT WILL RESULT IN PASSING MVFR CEILING AND VISIBILITY, BUT MAINLY CONFINED TO THE AREA NORTH OF DETROIT. NORTHWEST WINDS WILL GUST ONCE AGAIN UP TO 25 KNOTS AT ALL LOCATIONS. PREV DISCUSSION...ISSUED 352 PM EST THU NOV 20 2008 SHORT TERM...TONIGHT MAIN LAKE BAND OVER SOUTHERN LAKE HURON PROVIDED JUST A GLANCING BLOW TO THE EASTERN THUMB COASTLINE LATE THIS MORNING...WITH JUST A COUPLE INCHES REPORTED ALONG THE SOUTHEAST COAST OF HURON COUNTY BEFORE THE BAND PUSHED OFFSHORE. NOT READY TO GIVE UP ON THE REMAINING NORTHERLY BAND(S) NOTED OVER WESTERN LAKE HURON...AS CLOUD TOPS ARE STILL 8-10 KFT BASED OFF THE APX RADAR. LOW LEVEL WINDS OVER THE NORTH HALF OF LAKE HURON AND OVER EASTERN NORTHERN LOWER MICHIGAN HAVE BECOME A BIT MORE NORTHWEST...WHICH WILL ALLOW THE BAND(S) TO PUSH FARTHER OFFSHORE...BUT STILL BELIEVE FAR EASTERN HURON COUNTY WILL GET CLIPPED THROUGH TONIGHT...WITH ANOTHER 3 TO 6 INCHES EXPECTED ALONG THE SHORELINE....WHICH HAS SOME SUPPORT FROM THE 18Z RUC13...AS 925 MB OMEGA REALLY RAMPS UP LATE THIS EVENING OVER EASTERN HURON COUNTY. AS WAS THE CASE TODAY...THE EVENING SHIFT WILL HAVE TO KEEP CLOSE TABS ON EASTERN SANILAC COUNTY. LITTLE IF ANY SNOW ACCUMULATION EXPECTED WEST OF M-53. OUTSIDE OF THE EASTERN THUMB REGION...DIURNALLY ENHANCED FLURRIES/LIGHT SNOW SHOWERS SHOULD DISSIPATE AND RECEDE CLOSER TO LAKE MICHIGAN WITH THE UNFAVORABLE NNW FLOW...WITH SKIES AT LEAST BECOMING PARTLY CLOUDY...ALLOWING MINS TO DIP DOWN INTO THE UPPER TEENS TO LOWER 20S...DESPITE SURFACE WINDS FAILING TO DECOUPLE. LONG TERM...FRIDAY THROUGH THURSDAY COLD WEATHER PATTERN WILL PERSIST...BY AND LARGE...THROUGHOUT THIS FORECAST PERIOD. TO START THE DAY FRIDAY...A BULK OF THE LAKE EFFECT ACTIVITY WILL OFFSHORE OVER THE MIDDLE OF LAKE HURON. HOWEVER...THE TIP OF THE THUMB MAY RECEIVE ADDITIONAL LIGHT SNOW AMOUNTS DURING THE MORNING. A WEAK SHORTWAVE WILL BE WORKING THROUGH THE AREA AT THE SAME TIME...BRINGING SCATTERED SNOW SHOWERS TO THE CWA...MAINLY NORTH OF THE METRO DETROIT AREA. ONCE THIS WAVE PASSES...GENERALLY DRY CONDITIONS ARE EXPECTED FRIDAY NIGHT INTO SATURDAY NIGHT. AS A LARGE HIGH PRESSURE SETTLES FROM THE MID MISSISSIPPI VALLEY TO THE TENNESSEE VALLEY. ACTUALLY...DRY WEATHER WILL MOST LIKELY HOLD INTO SUNDAY AS WELL A AREA OF LIGHT SNOW WITHING ISENTROPIC LIFT REGIME WILL MAINLY STAY TO THE NORTH OF THE AREA AS IT SHIFTS NORTHEAST THROUGH THE NORTHERN GREAT LAKES. THIS WILL LEAVE SOUTHEAST MICHIGAN IN A RELATIVELY MILD POSITION AS SOUTH FLOW INCREASES IN WARM AIR ADVECTION PATTERN. HIGH TEMPERATURES WILL PUSH 40...PARTICULARLY WHERE LITTLE/NO SNOW COVER EXISTS...AS OPPOSED TO THE UPPER 20S/LOWER 30S ON FRIDAY/SATURDAY. UNSETTLED WEATHER RETURNS SUNDAY NIGHT INTO MONDAY AS A STRONG WAVE ROTATES THROUGH THE NORTHERN LAKES REGION. THE ASSOCIATED UPPER TROUGH LOOKS TO BE AMPLIFIED ENOUGH TO TAP AT LEAST SOME GULF OF MEXICO MOISTURE...WHICH SHOULD ENHANCE AN AREA OF LIGHT SNOW OR MIX OF SNOW/RAIN IN ADVANCE OF THE TROUGH AXIS. AS THIS SYSTEM DIGS INTO THE GREAT LAKES...AND FORMS THEN FORMS INTO A RATHER LARGE UPPER LOW OVER THE NORTHEAST CONUS...SCATTERED SNOW SHOWERS WILL AGAIN BE PREVALENT OVER THE REGION...AS COLD CYCLONIC FLOW BECOMES ESTABLISHED THROUGH TUESDAY. THE WEATHER PATTERN MAY VERY WELL QUIET DOWN AGAIN LATE IN THE FORECAST AS A SHORTWAVE RIDGE SHIFTS OVER THE AREA IN RESPONSE TO THE NEXT LARGE NORTHERN STREAM SHORTWAVE...WHICH LOOKS TO DIG INTO THE NORTHERN PLAINS INITIALLY. THIS WILL BRING MILD SOUTHERLY WINDS BACK INTO THE AREA WITH HIGHS BACK TO AROUND 40 BY WEDNESDAY/THURSDAY NEXT WEEK. WOULD HAVE TO SAY CONFIDENCE IS...AT BEST...MARGINAL GIVEN THE VIGOR OF THE UPCOMING SHORTWAVES AND THE INFLUENCE THEY WILL LIKELY HAVE ON THE OVERALL EVOLUTION WITHIN THE UPPER LEVEL PATTERN. MARINE... THE PRESSURE GRADIENT OVER THE LAKES WILL TIGHTEN UP JUST A BIT TONIGHT AS THE TEMPERATURES OF THE LAND FALL THROUGH THE 20S...RESULTING IN A MODEST INCREASE IN WIND SPEEDS OVER LAKE HURON OVERNIGHT. THE INCREASE IN WINDS AND WAVES WILL BE SHORT LIVED...AS SURFACE RIDGE BUILDING INTO THE CENTRAL GREAT LAKES THROUGH SATURDAY MORNING ALLOWS FOR THE WINDS AND WAVES TO SUBSIDE AND BRING AN END TO THE SNOW SHOWERS. && .DTX WATCHES/WARNINGS/ADVISORIES... MI...LAKE EFFECT SNOW ADVISORY...MIZ049...UNTIL 7 AM FRIDAY. LAKE HURON... SMALL CRAFT ADVISORY...OUTER SAGINAW BAY...UNTIL 4 AM SATURDAY. SMALL CRAFT ADVISORY...INNER SAGINAW BAY...UNTIL 7 AM FRIDAY. SMALL CRAFT ADVISORY...NEARSHORE WATERS FROM PORT AUSTIN TO PORT HURON...UNTIL 10 AM SATURDAY. LAKE ST CLAIR... SMALL CRAFT ADVISORY...UNTIL 7 AM FRIDAY. MI WATERS OF LAKE ERIE... SMALL CRAFT ADVISORY...UNTIL 7 AM FRIDAY. && $$ UPDATE.......BT AVIATION.....BT SHORT TERM...SF LONG TERM....DG MARINE.......SF YOU CAN OBTAIN YOUR LATEST NATIONAL WEATHER SERVICE FORECASTS ONLINE AT WWW.WEATHER.GOV/DETROIT (ALL LOWER CASE). mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI 703 PM EST THU NOV 20 2008 .AVIATION... SCATTERED SNOW SHOWERS ONGOING OVER SE MICHIGAN WILL DISSIPATE THIS EVENING AFTER DIMINISHING SUPPORT FROM THE LOW PRESSURE SYSTEM AND WITH THE LOSS OF DAYTIME HEATING. THIS WILL BE FOLLOWED BY A GRADUAL CLEARING TREND AS NW LOW LEVEL WIND FLOW PERSISTS. THIS IS A DRY FLOW FOR OUR AREA, ESPECIALLY AT NIGHT. VFR CONDITIONS WILL THEN CONTINUE THROUGH FRIDAY MORNING UNTIL CLOUDS INCREASE AGAIN BY AFTERNOON. ANOTHER ROUND OF SCATTERED SNOW SHOWERS IS EXPECTED DURING FRIDAY AFTERNOON THAT WILL RESULT IN PASSING MVFR CEILING AND VISIBILITY, BUT MAINLY CONFINED TO THE AREA NORTH OF DETROIT. NORTHWEST WINDS WILL GUST ONCE AGAIN UP TO 25 KNOTS AT ALL LOCATIONS. && .PREV DISCUSSION...ISSUED 352 PM EST THU NOV 20 2008 SHORT TERM...TONIGHT MAIN LAKE BAND OVER SOUTHERN LAKE HURON PROVIDED JUST A GLANCING BLOW TO THE EASTERN THUMB COASTLINE LATE THIS MORNING...WITH JUST A COUPLE INCHES REPORTED ALONG THE SOUTHEAST COAST OF HURON COUNTY BEFORE THE BAND PUSHED OFFSHORE. NOT READY TO GIVE UP ON THE REMAINING NORTHERLY BAND(S) NOTED OVER WESTERN LAKE HURON...AS CLOUD TOPS ARE STILL 8-10 KFT BASED OFF THE APX RADAR. LOW LEVEL WINDS OVER THE NORTH HALF OF LAKE HURON AND OVER EASTERN NORTHERN LOWER MICHIGAN HAVE BECOME A BIT MORE NORTHWEST...WHICH WILL ALLOW THE BAND(S) TO PUSH FARTHER OFFSHORE...BUT STILL BELIEVE FAR EASTERN HURON COUNTY WILL GET CLIPPED THROUGH TONIGHT...WITH ANOTHER 3 TO 6 INCHES EXPECTED ALONG THE SHORELINE....WHICH HAS SOME SUPPORT FROM THE 18Z RUC13...AS 925 MB OMEGA REALLY RAMPS UP LATE THIS EVENING OVER EASTERN HURON COUNTY. AS WAS THE CASE TODAY...THE EVENING SHIFT WILL HAVE TO KEEP CLOSE TABS ON EASTERN SANILAC COUNTY. LITTLE IF ANY SNOW ACCUMULATION EXPECTED WEST OF M-53. OUTSIDE OF THE EASTERN THUMB REGION...DIURNALLY ENHANCED FLURRIES/LIGHT SNOW SHOWERS SHOULD DISSIPATE AND RECEDE CLOSER TO LAKE MICHIGAN WITH THE UNFAVORABLE NNW FLOW...WITH SKIES AT LEAST BECOMING PARTLY CLOUDY...ALLOWING MINS TO DIP DOWN INTO THE UPPER TEENS TO LOWER 20S...DESPITE SURFACE WINDS FAILING TO DECOUPLE. LONG TERM...FRIDAY THROUGH THURSDAY COLD WEATHER PATTERN WILL PERSIST...BY AND LARGE...THROUGHOUT THIS FORECAST PERIOD. TO START THE DAY FRIDAY...A BULK OF THE LAKE EFFECT ACTIVITY WILL OFFSHORE OVER THE MIDDLE OF LAKE HURON. HOWEVER...THE TIP OF THE THUMB MAY RECEIVE ADDITIONAL LIGHT SNOW AMOUNTS DURING THE MORNING. A WEAK SHORTWAVE WILL BE WORKING THROUGH THE AREA AT THE SAME TIME...BRINGING SCATTERED SNOW SHOWERS TO THE CWA...MAINLY NORTH OF THE METRO DETROIT AREA. ONCE THIS WAVE PASSES...GENERALLY DRY CONDITIONS ARE EXPECTED FRIDAY NIGHT INTO SATURDAY NIGHT. AS A LARGE HIGH PRESSURE SETTLES FROM THE MID MISSISSIPPI VALLEY TO THE TENNESSEE VALLEY. ACTUALLY...DRY WEATHER WILL MOST LIKELY HOLD INTO SUNDAY AS WELL A AREA OF LIGHT SNOW WITHING ISENTROPIC LIFT REGIME WILL MAINLY STAY TO THE NORTH OF THE AREA AS IT SHIFTS NORTHEAST THROUGH THE NORTHERN GREAT LAKES. THIS WILL LEAVE SOUTHEAST MICHIGAN IN A RELATIVELY MILD POSITION AS SOUTH FLOW INCREASES IN WARM AIR ADVECTION PATTERN. HIGH TEMPERATURES WILL PUSH 40...PARTICULARLY WHERE LITTLE/NO SNOW COVER EXISTS...AS OPPOSED TO THE UPPER 20S/LOWER 30S ON FRIDAY/SATURDAY. UNSETTLED WEATHER RETURNS SUNDAY NIGHT INTO MONDAY AS A STRONG WAVE ROTATES THROUGH THE NORTHERN LAKES REGION. THE ASSOCIATED UPPER TROUGH LOOKS TO BE AMPLIFIED ENOUGH TO TAP AT LEAST SOME GULF OF MEXICO MOISTURE...WHICH SHOULD ENHANCE AN AREA OF LIGHT SNOW OR MIX OF SNOW/RAIN IN ADVANCE OF THE TROUGH AXIS. AS THIS SYSTEM DIGS INTO THE GREAT LAKES...AND FORMS THEN FORMS INTO A RATHER LARGE UPPER LOW OVER THE NORTHEAST CONUS...SCATTERED SNOW SHOWERS WILL AGAIN BE PREVALENT OVER THE REGION...AS COLD CYCLONIC FLOW BECOMES ESTABLISHED THROUGH TUESDAY. THE WEATHER PATTERN MAY VERY WELL QUIET DOWN AGAIN LATE IN THE FORECAST AS A SHORTWAVE RIDGE SHIFTS OVER THE AREA IN RESPONSE TO THE NEXT LARGE NORTHERN STREAM SHORTWAVE...WHICH LOOKS TO DIG INTO THE NORTHERN PLAINS INITIALLY. THIS WILL BRING MILD SOUTHERLY WINDS BACK INTO THE AREA WITH HIGHS BACK TO AROUND 40 BY WEDNESDAY/THURSDAY NEXT WEEK. WOULD HAVE TO SAY CONFIDENCE IS...AT BEST...MARGINAL GIVEN THE VIGOR OF THE UPCOMING SHORTWAVES AND THE INFLUENCE THEY WILL LIKELY HAVE ON THE OVERALL EVOLUTION WITHIN THE UPPER LEVEL PATTERN. MARINE... THE PRESSURE GRADIENT OVER THE LAKES WILL TIGHTEN UP JUST A BIT TONIGHT AS THE TEMPERATURES OF THE LAND FALL THROUGH THE 20S...RESULTING IN A MODEST INCREASE IN WIND SPEEDS OVER LAKE HURON OVERNIGHT. THE INCREASE IN WINDS AND WAVES WILL BE SHORT LIVED...AS SURFACE RIDGE BUILDING INTO THE CENTRAL GREAT LAKES THROUGH SATURDAY MORNING ALLOWS FOR THE WINDS AND WAVES TO SUBSIDE AND BRING AN END TO THE SNOW SHOWERS. && .DTX WATCHES/WARNINGS/ADVISORIES... MI...LAKE EFFECT SNOW WARNING...MIZ049...UNTIL 7 AM FRIDAY. LAKE HURON... SMALL CRAFT ADVISORY...OUTER SAGINAW BAY...UNTIL 4 AM SATURDAY. SMALL CRAFT ADVISORY...INNER SAGINAW BAY...UNTIL 7 AM FRIDAY. SMALL CRAFT ADVISORY...NEARSHORE WATERS FROM PORT AUSTIN TO PORT HURON...UNTIL 10 AM SATURDAY. LAKE ST CLAIR... SMALL CRAFT ADVISORY...UNTIL 7 AM FRIDAY. MI WATERS OF LAKE ERIE... SMALL CRAFT ADVISORY...UNTIL 7 AM FRIDAY. && $$ AVIATION.....BT SHORT TERM...SF LONG TERM....DG MARINE.......SF YOU CAN OBTAIN YOUR LATEST NATIONAL WEATHER SERVICE FORECASTS ONLINE AT WWW.WEATHER.GOV/DETROIT (ALL LOWER CASE). mi AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE MARQUETTE MI 648 PM EST THU NOV 20 2008 UPDATED AVIATION SECTION FOR 00Z TAFS .SYNOPSIS... 12Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW COLD NNW FLOW (12Z H85 TEMPS RANGE FM -18C AT YPL TO -14C AT GRB) OVER THE RELATIVELY WARM WATERS OF LK SUP (WATER TEMPS RANGE FM 5C OVER THE W TO 8C IN THE E) BTWN ARCTIC HI PRES OVER SCNTRL CAN AND LO PRES IN SE CAN. NMRS LES BANDS ARE EVIDENT OVER MAINLY THE E HALF OF THE LK. A LOOK AT 12Z RAOBS SEEMS TO INDICATE WHY THE LES IS HEAVIEST OVER THIS PORTION OF THE LK. SHALLOW CLDS OVER WRN LK SUP IS WHERE STABILITY IS HIER/AIRMASS DRIER PER 12Z INL RAOB...WHICH SHOWS INVRN BASE AT H9 UNDER BONE DRY MID LVLS. ALTHOUGH 12Z YPL RAOB INDICATES INVRN BASE NEAR H9 AS WELL...THAT SDNG SHOWS MSTR THRU H7. SO LES BANDS OVER THE E HALF OF THE LK ARE MUCH MORE WELL DVLPD...ESPECIALLY THE BAND FED BY APRNT MOISTENING OFF LK NIPIGON. 16Z TAMDAR SDNG FM SAW SHOWS INVRN BASE ARND H85...BUT TEMPS WITHIN THE MIXED LYR ARE IN THE -10C TO -17C RANGE AND QUITE FVRBL FOR DENDRITIC SN GROWTH. SO SN IS OF A VERY FLUFFY NATURE WITH HIER SN/WATER RATIOS. THE BANDS HAVE WEAKENED SOMEWHAT DURING THE DAY WITH DAYTIME HTG DIMINISHING THE SHARPER LAND BREEZE CNVGC THAT ACCOMPANIES A WSHFT TO MORE NW OVER LAND DURING NOCTURNAL COOLING. OTRW...A SHRTWV APPEARS TO BE DIGGING SWD THRU ONTARIO ARND CLOSED LO NEAR JAMES BAY. && .SHORT TERM DISCUSSION (TONIGHT AND FRI)... MAIN FCST CONCERNS ARE LES TRENDS/AMTS/GOING HEADLINES. FOR TNGT...SHRTWV OVER ONTARIO PROGGED TO SWING SEWD ACRS THE ERN ZNS AND TO NE LK HURON BY 12Z FRI. LLVL WINDS ARE PROGGED TO BACK MORE NW THRU THE NGT IN RESPONSE TO THIS TRACK. THIS SHRTWV MOTION WL SUPPORT HIER INVRN BASE/DEEPER MOIST LYR OVER THE ERN CWA (DOWNWIND OF YPL)...WITH LOWER INVRN HGT LIKELY OVER THE W UNDER HIER HGTS (DOWNWIND OF INL). H85 TEMPS PROGGED TO FALL A DEGREE OR TWO DURING THE NGT...SO THERMAL PROFILE WITHIN MIXED LYR WL REMAIN FVRBL FOR HIER SN/WATER RATIOS. SO...LARGER SCALE FACTORS FAVOR A CONTINUATION OF HEAVY LES OVER THE E WITH LESSER INTENSITY OVER THE W. MOST LIKELY FOCUS FOR REALLY HEFTY AMTS WL BE INITIALLY OVER THE CNTRL FM MQT-ESC...WHERE HIER RES LOCAL WRF-ARW/RUC13 MODELS HINT AT SHARPEST H925 CNVGC THRU 03Z. AS THE LARGER SCALE WINDS BACK MORE NW...THE MORE FVRBL LLVL CNVGC WL DRIFT TO THE E. DVLPMNT OF LAND BREEZE OFF THE WCNTRL HIER TERRAIN...WHERE TEMPS WL BE LOWEST TNGT...WL TEND TO REINFORCE THE INTENSITY OF THE WRN-MOST BAND. MOISTENING OFF LK NIPIGON WL CONT TO ENHANCE THIS BAND AS WELL. HINT OF LAND BREEZE OFF ONTARIO... MORE VEERED WIND OVER THE ERN U.P... MIGHT HAVE THE SAME IMPACT IN LUCE COUNTY. ON FRI...ANOTHER SHEARED OUT SHRTWV WL APRCH FM THE NW AND PASS OVER THE ERN COUNTIES DURING THE DAY. AS WL BE THE CASE TNGT...INVRN HGT/ DEPTH OF MOIST LYR WL REMAIN HI OVER THE E ON THE CYC TRACK OF THIS SHRTWV TRACK BUT QUITE A BIT LOWER OVER THE W. EXPECT THE HEAVIEST LES OVER THE E UNDER THIS HIER INVRN WITH LLVL FLOW ALSO SLOWLY BACKING MORE NW. 12Z NAM/RUC13/WRF-ARW HINT AT SHARP LLVL CNVGC OVER LUCE/ERN ALGER/SCHOOLCRAFT COUNTIES...SO GOING WRNGS THERE LOOK ON TRACK EVEN IF LAND BREEZE CNVGC FADES A BIT THRU THE DAY. OVERALL... GOING ADVYS/ HEADLINES SEEM APPROPRIATE. ONLY PSBL UPDATE TO HEADLINES MAY BE NECESSITY OF WRNG FOR SRN SCHOOLCRAFT COUNTY AND ABILITY TO CANX ADVY EARLY OVER THE W. COORDINATED WITH APX. .LONG TERM DISCUSSION (FRI NGT THRU THU)... DEPARTING MID LEVEL SHORTWAVE EXITS EASTERN CWA OVERNIGHT FRIDAY. EXPECT SOME LES TO LINGER ACROSS EASTERN ALGER AND LUCE COUNTIES THROUGH SUNRISE AS PROGGED NAM/GFS 925-850 DEWPOINT DP REMAIN LESS THAN 7 THROUGH THE AFTERNOON. WINDS LOOK TO TURN OFFSHORE BY 15Z...CUTTING OF LAKE EFFECT PROCESSES. HIGH PRESSURE WILL WORK ACROSS THE FA EARLY SATURDAY...AS THE HIGH SHIFT EAST OF LAKE SUPERIOR ON SATURDAY AFTN DRY SOUTHERLY FLOW KICKS IN. DID ADD IN SLIGHT CHANCE FOR FREEZING DRIZZLE BETWEEN 6Z AND 12Z SUNDAY AS LATEST BUFKIT PROFILES INDICATE SHALLOW MOISTURE BELOW 5KFT REMAINS WARMER THAN -10C ISOTHERM. .SUNDAY THROUGH TUESDAY MORNING...NEXT SYSTEM OF INTEREST WILL IMPACT THE FA SUNDAY NIGHT THROUGH LATE MONDAY. LOW PRESSURE IS PROGGED TO MOVE ACROSS THE NORTHERN CANADIAN PRAIRIES ON SUNDAY THEN DROP SOUTHEAST AND DEEPEN AS IT MOVES ACROSS THE UPPER GREAT LAKES ON MONDAY. LONG RANGE MODELS...ECMWF/GFS/GLBL-GEM...DISAGREE WITH OVERALL MOISTURE FIELDS...WHICH APPEARS MAINLY TO BE A FUNCTION OF THE UPSTREAM RIDGING. FLATTER 500MB RIDGE SUNDAY NIGHT IN ECMWF SOLUTION ALLOWS SYSTEM TO DROP FURTHER SOUTH. WHILE BOTH THE GFS AND GLBL-GEM HAVE MUCH BETTER DEFINED 500MB RIDGE EXTENDING BACK INTO HUDSON BAY. THE RESULT OF THIS MASS FIELD DIFFERENCE ALLOWS THE ECMWF LOW TO TRACK FURTHER SOUTH AND BE MORE PROGRESSIVE AND WEAKER...WHILE THE GFS/GLBL-GEM SOLUTIONS TRACK DIRECTLY OVER THE FCST AREA WITH A STRONGER/SLOWER PROGRESSION. AS FAR AS DETAILS GO...THIS TRANSLATES TO A HIGH IMPACT SYNOPTIC SNOW EVENT IN GFS WORLD AND A LOW IMPACT LES EVENT IN THE ECMWF SOLUTION. A QUICK LOOK AT SOME OF THE MASS FIELDS SHOWS MORE DIFFERENCES. LATEST ECMWF(12Z)...SHOWS GOOD MID LEVEL CONVERGENCE (PER 700-500MB DIVQ) THOUGH DEEP MOISTURE REMAINS EAST AND SOUTH OF THE FA. THE MORE BULLISH GFS SHOWS DEEP MOISTURE IS BETTER CO-LOCATED WITH BEST MID LEVEL CONVERGENCE FROM LATE SUNDAY NIGHT THROUGH MONDAY NIGHT AS THE LOW TRACKS DIRECTLY OVER THE U.P. FROM THEIR INITIALIZATION ITS HARD TO COME UP WITH ANY DIFFERENCE THAT WOULD LEAD TO THE VARYING SOLUTIONS. THUS HAVE MAINTAINED LOWER POPS THROUGHOUT. .TUESDAY MORNING THROUGH THURSDAY...TEMPORARY RIDGING WILL WORK ACROSS THE FA ON TUESDAY AND WEDNESDAY...ALLOWING TEMPERATURES TO TEMPORARILY WARM UP...THOUGH DON/T EXPECT TEMPERATURES TO QUITE REACH 40. TEMPERATURES ON THURSDAY ARE A VERY UNCERTAIN AT THIS POINT. 850MB TEMPS ARE AROUND -6 TO -8C IN THE GFS AND 0 TO +2C IN THE 12Z ECMWF SOLUTION...THIS DISCREPANCY IS DUE IN PART TO THE MODEL DIFFERENCES WITHIN THE PREVIOUS SYSTEM. THE NEXT SYSTEM BEGINS DIGGING INTO THE UPPER MISSISSIPPI VALLEY THURSDAY EVENING. BOTH THE GFS AND GLB-GEM AGREE WITH TIMING...THOUGH THERE ARE SIGNIFICANT STRENGTH DIFFERENCES. ECMWF SOLUTION KEEPS THIS SYSTEM OVER NORTHERN ONTARIO AND NORTH OF THE LAKES ALTOGETHER. && .AVIATION (FOR THE 00Z TAF ISSUANCE)... AT CMX...LK EFFECT SNOW BANDS WITH MVFR CIGS/VSBY THROUGH FRIDAY. HOWEVER...CONDITIONS MAY FALL TO IFR THIS EVENING AS MID LEVEL DISTURBANCE SHIFTS THROUGH AND ENHANCES THE SNOW. AT SAW...HEAVY LK EFFECT SNOW BAND HAS SHIFTED EAST OF SAW AS WINDS HAVE BACKED MORE NW. RESULT IS IMPROVING CONDITIONS OVR THOSE SEEN THE LAST 12 HRS. ALTHOUGH LK EFFECT WILL CONTINUE THROUGH LATE TONIGHT...CIGS AND VSBY WILL BE MORE IN THE MVFR RANGE. WINDS BECOMING WRLY SHOULD SHUT DOWN THE LK EFFECT AT SAW ON FRIDAY MORNING. && .MARINE (FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)... LOOK FOR LAKE SUPERIOR TO REMAIN SANDWICHED BETWEEN LOW PRESSURE OVER NEW ENGLAND AND HIGH PRESSURE BUILDING INTO THE NORTHERN PLAINS THROUGH FRIDAY AFTERNOON. AS A RESULT OF THIS STRONG PRESSURE GRADIENT...NORTH-NORTHWEST GALE FORCE WINDS TO 35 KNOTS ARE EXPECTED ACROSS NORTH CENTRAL AND EASTERN LAKES SUPERIOR THROUGH TONIGHT...WINDS WILL DIMINISH TO 30 KNOTS FRIDAY MORNING THROUGH FRIDAY AFTERNOON. NORTH-NORTHWEST WINDS WILL REACH NEAR GALE FORCE SUNDAY NIGHT INTO MONDAY ACROSS THE EAST HALF OF THE LAKE. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... LAKE EFFECT SNOW ADVISORY UNTIL 7 AM EST /6 AM CST/ FRIDAY FOR MIZ001>004-009-084. LAKE EFFECT SNOW WARNING UNTIL 10 PM EST FRIDAY FOR MIZ006-007- 085. LAKE EFFECT SNOW WARNING UNTIL 10 AM EST FRIDAY FOR MIZ005. LAKE EFFECT SNOW WARNING UNTIL 1 PM EST FRIDAY FOR MIZ013-014. LAKE SUPERIOR... GALE WARNING UNTIL 5 AM EST FRIDAY FOR LSZ266-267. GALE WARNING UNTIL 4 AM EST FRIDAY FOR LSZ265. GALE WARNING UNTIL 1 AM EST FRIDAY FOR LSZ243>245-264. GALE WARNING UNTIL 3 AM EST FRIDAY FOR LSZ249-250. GALE WARNING UNTIL 9 PM EST THIS EVENING FOR LSZ248. GALE WARNING UNTIL 8 PM EST THIS EVENING FOR LSZ263. LAKE MICHIGAN... GALE WARNING UNTIL 7 PM EST THIS EVENING FOR LMZ221-248-250. && $$ SYNOPSIS/SHORT TERM...KC LONG TERM...PEARSON AVIATION...JLA MARINE...PEARSON mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 402 PM EST THU NOV 20 2008 .SYNOPSIS... 12Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW COLD NNW FLOW (12Z H85 TEMPS RANGE FM -18C AT YPL TO -14C AT GRB) OVER THE RELATIVELY WARM WATERS OF LK SUP (WATER TEMPS RANGE FM 5C OVER THE W TO 8C IN THE E) BTWN ARCTIC HI PRES OVER SCNTRL CAN AND LO PRES IN SE CAN. NMRS LES BANDS ARE EVIDENT OVER MAINLY THE E HALF OF THE LK. A LOOK AT 12Z RAOBS SEEMS TO INDICATE WHY THE LES IS HEAVIEST OVER THIS PORTION OF THE LK. SHALLOW CLDS OVER WRN LK SUP IS WHERE STABILITY IS HIER/AIRMASS DRIER PER 12Z INL RAOB...WHICH SHOWS INVRN BASE AT H9 UNDER BONE DRY MID LVLS. ALTHOUGH 12Z YPL RAOB INDICATES INVRN BASE NEAR H9 AS WELL...THAT SDNG SHOWS MSTR THRU H7. SO LES BANDS OVER THE E HALF OF THE LK ARE MUCH MORE WELL DVLPD...ESPECIALLY THE BAND FED BY APRNT MOISTENING OFF LK NIPIGON. 16Z TAMDAR SDNG FM SAW SHOWS INVRN BASE ARND H85...BUT TEMPS WITHIN THE MIXED LYR ARE IN THE -10C TO -17C RANGE AND QUITE FVRBL FOR DENDRITIC SN GROWTH. SO SN IS OF A VERY FLUFFY NATURE WITH HIER SN/WATER RATIOS. THE BANDS HAVE WEAKENED SOMEWHAT DURING THE DAY WITH DAYTIME HTG DIMINISHING THE SHARPER LAND BREEZE CNVGC THAT ACCOMPANIES A WSHFT TO MORE NW OVER LAND DURING NOCTURNAL COOLING. OTRW...A SHRTWV APPEARS TO BE DIGGING SWD THRU ONTARIO ARND CLOSED LO NEAR JAMES BAY. && .SHORT TERM DISCUSSION (THU NT AND FRI)... MAIN FCST CONCERNS ARE LES TRENDS/AMTS/GOING HEADLINES. FOR TNGT...SHRTWV OVER ONTARIO PROGGED TO SWING SEWD ACRS THE ERN ZNS AND TO NE LK HURON BY 12Z FRI. LLVL WINDS ARE PROGGED TO BACK MORE NW THRU THE NGT IN RESPONSE TO THIS TRACK. THIS SHRTWV MOTION WL SUPPORT HIER INVRN BASE/DEEPER MOIST LYR OVER THE ERN CWA (DOWNWIND OF YPL)...WITH LOWER INVRN HGT LIKELY OVER THE W UNDER HIER HGTS (DOWNWIND OF INL). H85 TEMPS PROGGED TO FALL A DEGREE OR TWO DURING THE NGT...SO THERMAL PROFILE WITHIN MIXED LYR WL REMAIN FVRBL FOR HIER SN/WATER RATIOS. SO...LARGER SCALE FACTORS FAVOR A CONTINUATION OF HEAVY LES OVER THE E WITH LESSER INTENSITY OVER THE W. MOST LIKELY FOCUS FOR REALLY HEFTY AMTS WL BE INITIALLY OVER THE CNTRL FM MQT-ESC...WHERE HIER RES LOCAL WRF-ARW/RUC13 MODELS HINT AT SHARPEST H925 CNVGC THRU 03Z. AS THE LARGER SCALE WINDS BACK MORE NW...THE MORE FVRBL LLVL CNVGC WL DRIFT TO THE E. DVLPMNT OF LAND BREEZE OFF THE WCNTRL HIER TERRAIN...WHERE TEMPS WL BE LOWEST TNGT...WL TEND TO REINFORCE THE INTENSITY OF THE WRN-MOST BAND. MOISTENING OFF LK NIPIGON WL CONT TO ENHANCE THIS BAND AS WELL. HINT OF LAND BREEZE OFF ONTARIO... MORE VEERED WIND OVER THE ERN U.P... MIGHT HAVE THE SAME IMPACT IN LUCE COUNTY. ON FRI...ANOTHER SHEARED OUT SHRTWV WL APRCH FM THE NW AND PASS OVER THE ERN COUNTIES DURING THE DAY. AS WL BE THE CASE TNGT...INVRN HGT/ DEPTH OF MOIST LYR WL REMAIN HI OVER THE E ON THE CYC TRACK OF THIS SHRTWV TRACK BUT QUITE A BIT LOWER OVER THE W. EXPECT THE HEAVIEST LES OVER THE E UNDER THIS HIER INVRN WITH LLVL FLOW ALSO SLOWLY BACKING MORE NW. 12Z NAM/RUC13/WRF-ARW HINT AT SHARP LLVL CNVGC OVER LUCE/ERN ALGER/SCHOOLCRAFT COUNTIES...SO GOING WRNGS THERE LOOK ON TRACK EVEN IF LAND BREEZE CNVGC FADES A BIT THRU THE DAY. OVERALL... GOING ADVYS/ HEADLINES SEEM APPROPRIATE. ONLY PSBL UPDATE TO HEADLINES MAY BE NECESSITY OF WRNG FOR SRN SCHOOLCRAFT COUNTY AND ABILITY TO CANX ADVY EARLY OVER THE W. COORDINATED WITH APX. .LONG TERM DISCUSSION (FRI NGT THRU THU)... DEPARTING MID LEVEL SHORTWAVE EXITS EASTERN CWA OVERNIGHT FRIDAY. EXPECT SOME LES TO LINGER ACROSS EASTERN ALGER AND LUCE COUNTIES THROUGH SUNRISE AS PROGGED NAM/GFS 925-850 DEWPOINT DP REMAIN LESS THAN 7 THROUGH THE AFTERNOON. WINDS LOOK TO TURN OFFSHORE BY 15Z...CUTTING OF LAKE EFFECT PROCESSES. HIGH PRESSURE WILL WORK ACROSS THE FA EARLY SATURDAY...AS THE HIGH SHIFT EAST OF LAKE SUPERIOR ON SATURDAY AFTN DRY SOUTHERLY FLOW KICKS IN. DID ADD IN SLIGHT CHANCE FOR FREEZING DRIZZLE BETWEEN 6Z AND 12Z SUNDAY AS LATEST BUFKIT PROFILES INDICATE SHALLOW MOISTURE BELOW 5KFT REMAINS WARMER THAN -10C ISOTHERM. .SUNDAY THROUGH TUESDAY MORNING...NEXT SYSTEM OF INTEREST WILL IMPACT THE FA SUNDAY NIGHT THROUGH LATE MONDAY. LOW PRESSURE IS PROGGED TO MOVE ACROSS THE NORTHERN CANADIAN PRAIRIES ON SUNDAY THEN DROP SOUTHEAST AND DEEPEN AS IT MOVES ACROSS THE UPPER GREAT LAKES ON MONDAY. LONG RANGE MODELS...ECMWF/GFS/GLBL-GEM...DISAGREE WITH OVERALL MOISTURE FIELDS...WHICH APPEARS MAINLY TO BE A FUNCTION OF THE UPSTREAM RIDGING. FLATTER 500MB RIDGE SUNDAY NIGHT IN ECMWF SOLUTION ALLOWS SYSTEM TO DROP FURTHER SOUTH. WHILE BOTH THE GFS AND GLBL-GEM HAVE MUCH BETTER DEFINED 500MB RIDGE EXTENDING BACK INTO HUDSON BAY. THE RESULT OF THIS MASS FIELD DIFFERENCE ALLOWS THE ECMWF LOW TO TRACK FURTHER SOUTH AND BE MORE PROGRESSIVE AND WEAKER...WHILE THE GFS/GLBL-GEM SOLUTIONS TRACK DIRECTLY OVER THE FCST AREA WITH A STRONGER/SLOWER PROGRESSION. AS FAR AS DETAILS GO...THIS TRANSLATES TO A HIGH IMPACT SYNOPTIC SNOW EVENT IN GFS WORLD AND A LOW IMPACT LES EVENT IN THE ECMWF SOLUTION. A QUICK LOOK AT SOME OF THE MASS FIELDS SHOWS MORE DIFFERENCES. LATEST ECMWF(12Z)...SHOWS GOOD MID LEVEL CONVERGENCE (PER 700-500MB DIVQ) THOUGH DEEP MOISTURE REMAINS EAST AND SOUTH OF THE FA. THE MORE BULLISH GFS SHOWS DEEP MOISTURE IS BETTER CO-LOCATED WITH BEST MID LEVEL CONVERGENCE FROM LATE SUNDAY NIGHT THROUGH MONDAY NIGHT AS THE LOW TRACKS DIRECTLY OVER THE U.P. FROM THEIR INITIALIZATION ITS HARD TO COME UP WITH ANY DIFFERENCE THAT WOULD LEAD TO THE VARYING SOLUTIONS. THUS HAVE MAINTAINED LOWER POPS THROUGHOUT. .TUESDAY MORNING THROUGH THURSDAY...TEMPORARY RIDGING WILL WORK ACROSS THE FA ON TUESDAY AND WEDNESDAY...ALLOWING TEMPERATURES TO TEMPORARILY WARM UP...THOUGH DON/T EXPECT TEMPERATURES TO QUITE REACH 40. TEMPERATURES ON THURSDAY ARE A VERY UNCERTAIN AT THIS POINT. 850MB TEMPS ARE AROUND -6 TO -8C IN THE GFS AND 0 TO +2C IN THE 12Z ECMWF SOLUTION...THIS DISCREPANCY IS DUE IN PART TO THE MODEL DIFFERENCES WITHIN THE PREVIOUS SYSTEM. THE NEXT SYSTEM BEGINS DIGGING INTO THE UPPER MISSISSIPPI VALLEY THURSDAY EVENING. BOTH THE GFS AND GLB-GEM AGREE WITH TIMING...THOUGH THERE ARE SIGNIFICANT STRENGTH DIFFERENCES. ECMWF SOLUTION KEEPS THIS SYSTEM OVER NORTHERN ONTARIO AND NORTH OF THE LAKES ALTOGETHER. && .AVIATION (FOR THE 18Z TAF ISSUANCE)... AT CMX...KEPT PREVAILING CONDITIONS FOR THE FIRST 6HRS AT MVFR...BUT DID PUT A TEMPO PERIOD FOR IFR CONDITIONS...AS LK EFFECT SNOW BANDS CONTINUE TO MOVE THROUGH. AFTER 00Z...STARTED TO SLOWLY BRING THE VSBYS UP...DUE TO INTENSITY OF LES DIMINISHING AS WINDS TURN NW...BUT STILL KEPT AT MVFR VSBY AND CIGS. AT SAW...HAVE PREVAILING IFR VSBYS FOR FIRST 4HRS...WITH TEMPO LIFR VSBYS...AS STRONG LES AND UPSLOPE BANDS CONTINUE TO MOVE ACROSS SAW. EXPECT THE BANDS TO GRADUALLY SHIFT E DURING THE LATE AFTN AND EVENING...AS WINDS BACK NW...SO HAVE TRANSITIONED TO MVFR AFTER 02Z. KEPT EXISTING MVFR CIGS AFTER 08Z...BUT HIGH VSBYS...DUE TO MAIN LES BANDS MOVING E AND SAW IN UNFAVORABLE NW WIND LES LOCATION. && .MARINE (FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)... LOOK FOR LAKE SUPERIOR TO REMAIN SANDWICHED BETWEEN LOW PRESSURE OVER NEW ENGLAND AND HIGH PRESSURE BUILDING INTO THE NORTHERN PLAINS THROUGH FRIDAY AFTERNOON. AS A RESULT OF THIS STRONG PRESSURE GRADIENT...NORTH-NORTHWEST GALE FORCE WINDS TO 35 KNOTS ARE EXPECTED ACROSS NORTH CENTRAL AND EASTERN LAKES SUPERIOR THROUGH TONIGHT...WINDS WILL DIMINISH TO 30 KNOTS FRIDAY MORNING THROUGH FRIDAY AFTERNOON. NORTH-NORTHWEST WINDS WILL REACH NEAR GALE FORCE SUNDAY NIGHT INTO MONDAY ACROSS THE EAST HALF OF THE LAKE. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... LAKE EFFECT SNOW ADVISORY UNTIL 7 AM EST /6 AM CST/ FRIDAY FOR MIZ001>004-009-084. LAKE EFFECT SNOW WARNING UNTIL 10 PM EST FRIDAY FOR MIZ006-007- 085. LAKE EFFECT SNOW WARNING UNTIL 10 AM EST FRIDAY FOR MIZ005. LAKE EFFECT SNOW WARNING UNTIL 1 PM EST FRIDAY FOR MIZ013-014. LAKE SUPERIOR... GALE WARNING UNTIL 5 AM EST FRIDAY FOR LSZ266-267. GALE WARNING UNTIL 4 AM EST FRIDAY FOR LSZ265. GALE WARNING UNTIL 1 AM EST FRIDAY FOR LSZ243>245-264. GALE WARNING UNTIL 3 AM EST FRIDAY FOR LSZ249-250. GALE WARNING UNTIL 9 PM EST THIS EVENING FOR LSZ248. GALE WARNING UNTIL 8 PM EST THIS EVENING FOR LSZ263. LAKE MICHIGAN... GALE WARNING UNTIL 7 PM EST THIS EVENING FOR LMZ221-248-250. && $$ SYNOPSIS/SHORT TERM...KC LONG TERM...PEARSON AVIATION...SRF MARINE...PEARSON mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI 352 PM EST THU NOV 20 2008 .SHORT TERM...TONIGHT MAIN LAKE BAND OVER SOUTHERN LAKE HURON PROVIDED JUST A GLANCING BLOW TO THE EASTERN THUMB COASTLINE LATE THIS MORNING...WITH JUST A COUPLE INCHES REPORTED ALONG THE SOUTHEAST COAST OF HURON COUNTY BEFORE THE BAND PUSHED OFFSHORE. NOT READY TO GIVE UP ON THE REMAINING NORTHERLY BAND(S) NOTED OVER WESTERN LAKE HURON...AS CLOUD TOPS ARE STILL 8-10 KFT BASED OFF THE APX RADAR. LOW LEVEL WINDS OVER THE NORTH HALF OF LAKE HURON AND OVER EASTERN NORTHERN LOWER MICHIGAN HAVE BECOME A BIT MORE NORTHWEST...WHICH WILL ALLOW THE BAND(S) TO PUSH FARTHER OFFSHORE...BUT STILL BELIEVE FAR EASTERN HURON COUNTY WILL GET CLIPPED THROUGH TONIGHT...WITH ANOTHER 3 TO 6 INCHES EXPECTED ALONG THE SHORELINE....WHICH HAS SOME SUPPORT FROM THE 18Z RUC13...AS 925 MB OMEGA REALLY RAMPS UP LATE THIS EVENING OVER EASTERN HURON COUNTY. AS WAS THE CASE TODAY...THE EVENING SHIFT WILL HAVE TO KEEP CLOSE TABS ON EASTERN SANILAC COUNTY. LITTLE IF ANY SNOW ACCUMULATION EXPECTED WEST OF M-53. OUTSIDE OF THE EASTERN THUMB REGION...DIURNALLY ENHANCED FLURRIES/LIGHT SNOW SHOWERS SHOULD DISSIPATE AND RECEDE CLOSER TO LAKE MICHIGAN WITH THE UNFAVORABLE NNW FLOW...WITH SKIES AT LEAST BECOMING PARTLY CLOUDY...ALLOWING MINS TO DIP DOWN INTO THE UPPER TEENS TO LOWER 20S...DESPITE SURFACE WINDS FAILING TO DECOUPLE. && .LONG TERM...FRIDAY THROUGH THURSDAY COLD WEATHER PATTERN WILL PERSIST...BY AND LARGE...THROUGHOUT THIS FORECAST PERIOD. TO START THE DAY FRIDAY...A BULK OF THE LAKE EFFECT ACTIVITY WILL OFFSHORE OVER THE MIDDLE OF LAKE HURON. HOWEVER...THE TIP OF THE THUMB MAY RECEIVE ADDITIONAL LIGHT SNOW AMOUNTS DURING THE MORNING. A WEAK SHORTWAVE WILL BE WORKING THROUGH THE AREA AT THE SAME TIME...BRINGING SCATTERED SNOW SHOWERS TO THE CWA...MAINLY NORTH OF THE METRO DETROIT AREA. ONCE THIS WAVE PASSES...GENERALLY DRY CONDITIONS ARE EXPECTED FRIDAY NIGHT INTO SATURDAY NIGHT. AS A LARGE HIGH PRESSURE SETTLES FROM THE MID MISSISSIPPI VALLEY TO THE TENNESSEE VALLEY. ACTUALLY...DRY WEATHER WILL MOST LIKELY HOLD INTO SUNDAY AS WELL A AREA OF LIGHT SNOW WITHING ISENTROPIC LIFT REGIME WILL MAINLY STAY TO THE NORTH OF THE AREA AS IT SHIFTS NORTHEAST THROUGH THE NORTHERN GREAT LAKES. THIS WILL LEAVE SOUTHEAST MICHIGAN IN A RELATIVELY MILD POSITION AS SOUTH FLOW INCREASES IN WARM AIR ADVECTION PATTERN. HIGH TEMPERATURES WILL PUSH 40...PARTICULARLY WHERE LITTLE/NO SNOW COVER EXISTS...AS OPPOSED TO THE UPPER 20S/LOWER 30S ON FRIDAY/SATURDAY. UNSETTLED WEATHER RETURNS SUNDAY NIGHT INTO MONDAY AS A STRONG WAVE ROTATES THROUGH THE NORTHERN LAKES REGION. THE ASSOCIATED UPPER TROUGH LOOKS TO BE AMPLIFIED ENOUGH TO TAP AT LEAST SOME GULF OF MEXICO MOISTURE...WHICH SHOULD ENHANCE AN AREA OF LIGHT SNOW OR MIX OF SNOW/RAIN IN ADVANCE OF THE TROUGH AXIS. AS THIS SYSTEM DIGS INTO THE GREAT LAKES...AND FORMS THEN FORMS INTO A RATHER LARGE UPPER LOW OVER THE NORTHEAST CONUS...SCATTERED SNOW SHOWERS WILL AGAIN BE PREVALENT OVER THE REGION...AS COLD CYCLONIC FLOW BECOMES ESTABLISHED THROUGH TUESDAY. THE WEATHER PATTERN MAY VERY WELL QUIET DOWN AGAIN LATE IN THE FORECAST AS A SHORTWAVE RIDGE SHIFTS OVER THE AREA IN RESPONSE TO THE NEXT LARGE NORTHERN STREAM SHORTWAVE...WHICH LOOKS TO DIG INTO THE NORTHERN PLAINS INITIALLY. THIS WILL BRING MILD SOUTHERLY WINDS BACK INTO THE AREA WITH HIGHS BACK TO AROUND 40 BY WEDNESDAY/THURSDAY NEXT WEEK. WOULD HAVE TO SAY CONFIDENCE IS...AT BEST...MARGINAL GIVEN THE VIGOR OF THE UPCOMING SHORTWAVES AND THE INFLUENCE THEY WILL LIKELY HAVE ON THE OVERALL EVOLUTION WITHIN THE UPPER LEVEL PATTERN. && .MARINE... THE PRESSURE GRADIENT OVER THE LAKES WILL TIGHTEN UP JUST A BIT TONIGHT AS THE TEMPERATURES OF THE LAND FALL THROUGH THE 20S...RESULTING IN A MODEST INCREASE IN WIND SPEEDS OVER LAKE HURON OVERNIGHT. THE INCREASE IN WINDS AND WAVES WILL BE SHORT LIVED...AS SURFACE RIDGE BUILDING INTO THE CENTRAL GREAT LAKES THROUGH SATURDAY MORNING ALLOWS FOR THE WINDS AND WAVES TO SUBSIDE AND BRING AN END TO THE SNOW SHOWERS. && .PREV DISCUSSION...ISSUED 1240 PM EST THU NOV 20 2008 AVIATION... PREDOMINATELY VFR CONDITIONS WILL CONTINUE THIS AFTERNOON...BUT DIURNAL INSTABILITY SHOULD ALLOW FOR EMBEDDED MVFR LIGHT SNOW SHOWERS. UNFAVORABLY NNW TRAJECTORY AND LOSS OF DAYTIME INSTABILITY IS EXPECTED TO ALLOW SKIES TO BECOME PARTLY CLOUDY THIS EVENING INTO TONIGHT. LOW LEVEL WINDS BACKING TO A SLIGHTLY MORE WESTERLY DIRECTION TOMORROW MORNING SHOULD ALLOW LOW CLOUDS (NEAR 3000 FEET) AND SNOW SHOWERS TO PUSH EAST INTO OUR CWA DURING THE DAY. WINDS WILL BE WITHIN A COUPLE DEGREES OF A NORTHWEST DIRECTION THROUGH THE PERIOD...GENERALLY IN THE 8 TO 16 KNOT RANGE...WITH SLIGHTLY HIGHER GUSTS. && .DTX WATCHES/WARNINGS/ADVISORIES... MI...LAKE EFFECT SNOW WARNING...MIZ049...UNTIL 7 AM FRIDAY. LAKE HURON... SMALL CRAFT ADVISORY...OUTER SAGINAW BAY...UNTIL 4 AM SATURDAY. SMALL CRAFT ADVISORY...INNER SAGINAW BAY...UNTIL 7 AM FRIDAY. SMALL CRAFT ADVISORY...NEARSHORE WATERS FROM PORT AUSTIN TO PORT HURON...UNTIL 10 AM SATURDAY. LAKE ST CLAIR... SMALL CRAFT ADVISORY...UNTIL 7 AM FRIDAY. MI WATERS OF LAKE ERIE... SMALL CRAFT ADVISORY...UNTIL 7 AM FRIDAY. && $$ SHORT TERM...SF LONG TERM....DG MARINE.......SF AVIATION.....SF YOU CAN OBTAIN YOUR LATEST NATIONAL WEATHER SERVICE FORECASTS ONLINE AT WWW.WEATHER.GOV/DETROIT (ALL LOWER CASE). mi AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE MARQUETTE MI 1224 AM EST THU NOV 20 2008 UPDATED FOR 06Z AVIATION DISCUSSION .UPDATE... BIGGEST CHANGE ON UPDATE WAS TO START THE LES ADVISORY FOR DELTA COUNTY NOW INSTEAD OF THU MORNING AS STRONG NNW FLOW IS DISPLACING DOMINANT BANDS INTO THE NRN HALF OF THE COUNTY PER RADAR LOOP. WENT WITH AMOUNTS UP OF 1 TO LOCALLY 4 INCHES FOR THE REST OF TONIGHT WITH THE GREATEST AMOUNTS NORTH OF US-2. ALSO BUMPED UP AMTS SLIGHTLY OVER THE KEWEENAW AS THE WRF-ARW INDICATES THAT A DOMINANT BAND COULD SET UP THERE OVERNIGHT IN AREA OF ENHANCED LOW-LEVEL CONVERGENCE. WE HAD OCCASIONAL REPORTS OF SLEET THIS EVENING MIXING WITH THE SNOW...AND NOT SURPRISINGLY..THE KSAW TAMDAR SNDG INDICATED NEAR SFC LYR TEMPS TO SUPPORT AGGREGATION PROCESSES FOR SLEET TO TAKE PLACE BENEATH THE DENDRITIC SNOW GROWTH LYR. EXPECT SLEET TO BE BRIEF AS COLDER TEMPS ADVECTING ACROSS THE AREA TONIGHT WILL SHIFT MUCH OF THE NEAR-SFC TEMPERATURE PROFILE INTO THE DENDRITIC GROWTH ZONE. THE REST OF THE WARNING AND ADVISORY HEADLINES STILL LOOK GOOD WITH THE HEAVIEST SNOW EXPECTED OVER THE ERN HALF OF MQT COUNTY AND WRN ALGER COUNTY OVERNIGHT INTO THU MORNING WHERE THE BEST LOCALIZED LOW-LEVEL CONVERGENCE IS INDICATED. && .SYNOPSIS... WV IMAGERY AND RUC ANALYSIS INDICATED NW MID/UPPER LEVEL FLOW THROUGH THE NRN PLAINS AND WESTERN GREAT LAKES BTWN A RDG OVER WRN NOAM AND A TROUGH FROM HUDSON BAY THROUGH NRN NEW ENGLAND. A CLIPPER SHORTWAVE TROUGH WAS LOCATED OVER LAKE SUPERIOR WITH ANOTHER UPSTREAM MOVING INTO SRN SASK. AT THE SFC...LOW PRES WAS LOCATED OVER ERN LAKE SUPERIOR WITH A TROUGH TO THE SSE TO NEAR KERY AND THROUGH LAKE MI. SNOW SHOWERS OVER CNTRL UPPER MI WERE ASSOCIATED WITH LOW LEVEL CONV ALONG THE COLD FRONT MOVING IN WITH WINDS VEERING NNW IN ITS WAKE. .SHORT TERM...(TONIGHT AND THURSDAY) ALTHOUGH THE SASK SHRTWV IS EXPECTED TO SLIDE FAR ENOUGH SE OF UPPER MI IT WILL HELP DEEPEN THE ERN CONUS TROUGH AND DRAW COLD AIR OVER NRN ONTARIO AND NRN MANITOBA SOUTHWARD. CAA BEHIND THE FRONT WILL DROP 850 MB TEMPERATURES FROM -8C TO -11 AT 00Z/THU TO -12C TO -16C 12Z/THU AND TO NEAR-17C BY 00Z/FRI...PER NAM/GFS BLEND. WITH LAKE TEMPS AROUND 5C LAKE-850 MB DELTA/T...INSTABILITY WILL BE STRONG ENOUGH (LAKE INDUCED CAPE CLIMBING FROM AROUND 300 J/KG TO 700 J/KG) TO SUPPORT MODERATE TO HEAVY SNOW SHOWERS INTO NNW FLOW SNOWBELTS OFF OF LAKE SUPERIOR. INVERSION HEIGHTS WILL ALSO BE FAVORABLE...IN THE 7K-10K FT RANGE. GOOD SNOWGROWTH PROFILE WITH BULK OF STRONGER CONVECTION OR UPWARD MOTION IN THE LAKE CLOUDS IN THE -12C TO -17C LAYER SHOULD ALSO BOOST SNOW/RATIO TO AROUND 25/1 BY THU. THE LCLY RUN HIGH RES WRF/ARW AND REGIONAL WRF/ARW IN ADDITION TO THE NAM SUGGEST THAT THE STRONGEST AND MOST PERSISTENT LOW LEVEL CONVERGENCE AND HEAVIER SNOWBAND POTENTIAL IS EXPECTED FROM ERN MARQUETTE COUNTY AND THE FAR WRN PORTION OF ALGER COUNTY. BANDS ORIGINATING OFF OF LAKE NIPIGON MAY ALSO LINE UP FROM NEAR KCMX INTO BARAGA COUNTY BEFORE WEAKENING THU. HOWEVER...GENERALLY OVER THE WEST...THE SLIGHTLY SHORTER FETCH SHOULD LIMIT LES POTENTIAL INTO THE ADVISORY RANGE WITH AMOUNTS MAINLY IN THE 2-5 INCH/PER 12 HOUR RANGE. .SHORT TERM...(THURSDAY NIGHT THROUGH WEDNESDAY) .THURSDAY NIGHT THROUGH FRIDAY NIGHT...BY THIS TIME THE CLIPPER SYSTEM THAT BROUGHT LIGHT SNOW AND ISOLATED REPORTS OF FREEZING DRIZZLE THIS MORNING BECOMES ABSORBED BY A STRONGER LOW MOVING INTO NOVA SCOTIA. BEHIND IT...STRONG LAKE EFFECT PROCESSES WILL DEVELOP AS NOTED ABOVE. EXPECT SIGNIFICANT SNOW ACCUMULATIONS AS 850MB TEMPS FALL TO AROUND -18C AND WINDS TURN NORTHERLY BEHIND PREVIOUSLY MENTIONED CLIPPER. DURING THURSDAY NIGHT THE FOCUS FOR THE HEAVIEST SNOW WILL GRADUALLY SHIFT EASTWARD INTO FAR EASTERN MARQUETTE COUNTY...ALGER COUNTY. CURRENT FORECAST CALLS FOR 8 PLUS INCHES OF SNOW FROM SKANDIA EASTWARD TO WETMORE AND MELSTRAND. BY FRIDAY THE OVERALL WIND FIELD BACKS MORE NORTHWESTERLY...AS A RESULT...LAKE EFFECT BANDS WILL SHIFT EVEN MORE EAST...ANOTHER 5 TO 6 INCHES CAN BE EXPECTED EAST OF A LINE FROM DEERTON TO TRENARY. THERE IS SOME CONCERN THAT SLR COULD BE HIGHER THAN THE 25:1 CURRENTLY ANTICIPATED. A QUICK LOOK AT LATEST NAM BUFKIT SOUNDINGS SHOW AN INCREASING SLR TREND THROUGHOUT THE EVENT AS THE BEST LIFT BECOMES BETTER CO-LOCATED WITH THE SNOW GROWTH LAYER. THE COBB SLR METHOD POINTS TO SLR RANGING FROM 15/20:1 TONIGHT AND THURSDAY AND INCREASING TO 30/35:1 BY FRIDAY. OBVIOUSLY SLIGHT CHANGES IN SLR CAN GREATLY AFFECT THE OVERALL TOTAL. FROM TONIGHT THROUGH FRIDAY NIGHT...A STORM TOTAL ACCUMULATION OF UP TO TWO FEET OF SNOW CAN BE EXPECTED ACROSS PORTIONS OF ALGER COUNTY AND FAR EASTERN MARQUETTE COUNTY (EAST OF SKANDIA)...AND A GENERAL FOOT TO FOOT AND A HALF ACROSS THE REST OF NORTHERN MARQUETTE COUNTY...AS WELL AS PORTIONS OF THE WESTERN U.P. FOR ADDITIONAL STORM TOTAL DETAILS SEE THE LATEST WSWMQT PRODUCT. .FRIDAY NIGHT THROUGH MONDAY...LES WILL GRADUALLY DIMINISH THROUGHOUT FRIDAY NIGHT AS SFC HIGH PRESSURE SHIFT INTO THE UPPER GREAT LAKES...IN FACT LES SHOULD BE OVER BEFORE MIDNIGHT ACROSS FAR WESTERN LES NW WIND SNOW BELTS. THIS TEMPORARY LULL IN LES WON/T LAST LONG AS NEXT SYSTEM IS ON OUR DOORSTEP BY SUNDAY NIGHT. LATEST GFS GUIDANCE PROGS A SFC LOW MOVING FROM LAKE WINNIPEG SUNDAY NIGHT TO GEORGIAN BAY BY MONDAY NIGHT. THEREAFTER THE LOW BASICALLY STALLS THROUGH TUESDAY MORNING. THE RESULTING NORTHERLY FLOW WOULD RESULT IN A ANOTHER SUBSTANTIAL LAKE EFFECT SNOW EVENT ON TUESDAY. HOWEVER...THE 00Z ECMWF SOLUTION DEPICTS A MORE SOUTHERLY AND MORE PROGRESSIVE LOW TRACK. THIS WOULD SUGGEST A MINOR LES EVENT AND A MODERATE SYNOPTIC SNOW EVENT AS THE LOW TRACKS DIRECTLY OVER THE U.P. && .AVIATION (FOR THE 06Z TAF ISSUANCE)... UPSTREAM 00Z SNDGS AT KINL AND CWPL INDICATING FAIRLY DRY LOW-LEVEL AIR BENEATH SUBSIDENCE INVERSION WHICH APPEARS TO BE HAVING AN ADVERSE EFFECT ON LES BANDS OVER WRN LAKE SUPERIOR. THUS AT KCMX...HAVE DECIDED TO GO A BIT MORE OPTIMISTIC AT KCMX FOR OVERNIGHT WITH PREVAILING VFR VSBY AND A TEMPO GRP FOR MVFR VSBYS. KEPT IFR VSBYS FOR THU 15-19Z TIME FRAME AS LOCAL MODELS INDICATE A DOMINANT LES COULD MOVE OVER ACROSS THE AREA. WINDS BACKING TO LESS FAVORABLE NW FLOW BY MID-LATE AFTERNOON SHOULD LEAD TO MVFR CONDITIONS INTO THE THU EVENING. AT KSAW...PERSISTENT GUSTY NRLY FLOW WILL BE MORE FAVORABLE FOR PREVAILING IFR VSBYS IN SHSN/BLSN INTO MID THU AFTERNOON. BACKING FLOW TO NW LATE IN THE DAY WILL BE LESS FAVORABLE FOR DOMINANT LES BANDS SO IMPROVED CONDITIONS TO MVFR FOR LATE AFTERNOON INTO THE EVENING HOURS. && .MARINE (FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)... LOW PRESSURE OVER CNTRL LK SUPERIOR WILL SLIDE SE AND OVER LK HURON BY 06Z THURSDAY. STRONG NORTHERLY WINDS WILL MOVE IN BEHIND THE LOW...WITH GALES TO 35 KNOTS EXPECTED OVER MOST OF LK SUPERIOR. THE STRONGEST WINDS WILL OCCUR OVER THE CENTRAL PORTIONS OF THE LK THIS EVENING...AS PRESSURE RISE COUPLET SLIDES ACROSS THE LAKE. THIS SHOULD PRODUCE GUSTS TO 40 KNOTS BETWEEN ISLE ROYALE AND GRAND MARAIS. WINDS WILL DIMINISH TO 30 KNOTS ON THURS AFTN...AS HIGH PRESSURE MOVES INTO THE NORTHERN PLAINS. WINDS TO 30 KNOTS WILL CONTINUE INTO EARLY FRIDAY MORNING OVER NORTH CENTRAL AND EASTERN LAKE SUPERIOR. WINDS WILL GRADUALLY DIMINISH ON FRIDAY INTO SATURDAY AS THE HIGH MOVES OVER LAKE SUPERIOR. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... LAKE EFFECT SNOW ADVISORY UNTIL 7 AM EST /6 AM CST/ FRIDAY FOR MIZ001>004-009-084. LAKE EFFECT SNOW ADVISORY UNTIL 1 PM EST FRIDAY FOR MIZ085. LAKE EFFECT SNOW WARNING UNTIL 1 PM EST FRIDAY FOR MIZ006. LAKE EFFECT SNOW WARNING UNTIL 10 AM EST FRIDAY FOR MIZ005. LAKE EFFECT SNOW ADVISORY UNTIL 1 PM EST FRIDAY FOR MIZ013. LAKE SUPERIOR... GALE WARNING UNTIL 7 AM EST THURSDAY FOR LSZ267. GALE WARNING UNTIL 4 PM EST THURSDAY FOR LSZ266. GALE WARNING UNTIL 11 AM EST THURSDAY FOR LSZ264-265. GALE WARNING UNTIL 6 AM EST THURSDAY FOR LSZ249-250. GALE WARNING UNTIL 5 AM EST THURSDAY FOR LSZ248. GALE WARNING UNTIL 8 AM EST THURSDAY FOR LSZ243>245. GALE WARNING UNTIL 7 AM EST THURSDAY FOR LSZ263. LAKE MICHIGAN... GALE WARNING UNTIL 10 AM EST THURSDAY FOR LMZ250. && $$ UPDATE...VOSS SYNOPSIS...JLB SHORT TERM...JLB LONG TERM...PEARSON AVIATION...VOSS MARINE...SRF/PEARSON mi AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE MARQUETTE MI 1045 PM EST WED NOV 19 2008 .UPDATE... BIGGEST CHANGE ON UPDATE WAS TO START THE LES ADVISORY FOR DELTA COUNTY NOW INSTEAD OF THU MORNING AS STRONG NNW FLOW IS DISPLACING DOMINANT BANDS INTO THE NRN HALF OF THE COUNTY PER RADAR LOOP. WENT WITH AMOUNTS UP OF 1 TO LOCALLY 4 INCHES FOR THE REST OF TONIGHT WITH THE GREATEST AMOUNTS NORTH OF US-2. ALSO BUMPED UP AMTS SLIGHTLY OVER THE KEWEENAW AS THE WRF-ARW INDICATES THAT A DOMINANT BAND COULD SET UP THERE OVERNIGHT IN AREA OF ENHANCED LOW-LEVEL CONVERGENCE. WE HAD OCCASIONAL REPORTS OF SLEET THIS EVENING MIXING WITH THE SNOW...AND NOT SURPRISINGLY..THE KSAW TAMDAR SNDG INDICATED NEAR SFC LYR TEMPS TO SUPPORT AGGREGATION PROCESSES FOR SLEET TO TAKE PLACE BENEATH THE DENDRITIC SNOW GROWTH LYR. EXPECT SLEET TO BE BRIEF AS COLDER TEMPS ADVECTING ACROSS THE AREA TONIGHT WILL SHIFT MUCH OF THE NEAR-SFC TEMPERATURE PROFILE INTO THE DENDRITIC GROWTH ZONE. THE REST OF THE WARNING AND ADVISORY HEADLINES STILL LOOK GOOD WITH THE HEAVIEST SNOW EXPECTED OVER THE ERN HALF OF MQT COUNTY AND WRN ALGER COUNTY OVERNIGHT INTO THU MORNING WHERE THE BEST LOCALIZED LOW-LEVEL CONVERGENCE IS INDICATED. && .SYNOPSIS... WV IMAGERY AND RUC ANALYSIS INDICATED NW MID/UPPER LEVEL FLOW THROUGH THE NRN PLAINS AND WESTERN GREAT LAKES BTWN A RDG OVER WRN NOAM AND A TROUGH FROM HUDSON BAY THROUGH NRN NEW ENGLAND. A CLIPPER SHORTWAVE TROUGH WAS LOCATED OVER LAKE SUPERIOR WITH ANOTHER UPSTREAM MOVING INTO SRN SASK. AT THE SFC...LOW PRES WAS LOCATED OVER ERN LAKE SUPERIOR WITH A TROUGH TO THE SSE TO NEAR KERY AND THROUGH LAKE MI. SNOW SHOWERS OVER CNTRL UPPER MI WERE ASSOCIATED WITH LOW LEVEL CONV ALONG THE COLD FRONT MOVING IN WITH WINDS VEERING NNW IN ITS WAKE. .SHORT TERM...(TONIGHT AND THURSDAY) ALTHOUGH THE SASK SHRTWV IS EXPECTED TO SLIDE FAR ENOUGH SE OF UPPER MI IT WILL HELP DEEPEN THE ERN CONUS TROUGH AND DRAW COLD AIR OVER NRN ONTARIO AND NRN MANITOBA SOUTHWARD. CAA BEHIND THE FRONT WILL DROP 850 MB TEMPERATURES FROM -8C TO -11 AT 00Z/THU TO -12C TO -16C 12Z/THU AND TO NEAR-17C BY 00Z/FRI...PER NAM/GFS BLEND. WITH LAKE TEMPS AROUND 5C LAKE-850 MB DELTA/T...INSTABILITY WILL BE STRONG ENOUGH (LAKE INDUCED CAPE CLIMBING FROM AROUND 300 J/KG TO 700 J/KG) TO SUPPORT MODERATE TO HEAVY SNOW SHOWERS INTO NNW FLOW SNOWBELTS OFF OF LAKE SUPERIOR. INVERSION HEIGHTS WILL ALSO BE FAVORABLE...IN THE 7K-10K FT RANGE. GOOD SNOWGROWTH PROFILE WITH BULK OF STRONGER CONVECTION OR UPWARD MOTION IN THE LAKE CLOUDS IN THE -12C TO -17C LAYER SHOULD ALSO BOOST SNOW/RATIO TO AROUND 25/1 BY THU. THE LCLY RUN HIGH RES WRF/ARW AND REGIONAL WRF/ARW IN ADDITION TO THE NAM SUGGEST THAT THE STRONGEST AND MOST PERSISTENT LOW LEVEL CONVERGENCE AND HEAVIER SNOWBAND POTENTIAL IS EXPECTED FROM ERN MARQUETTE COUNTY AND THE FAR WRN PORTION OF ALGER COUNTY. BANDS ORIGINATING OFF OF LAKE NIPIGON MAY ALSO LINE UP FROM NEAR KCMX INTO BARAGA COUNTY BEFORE WEAKENING THU. HOWEVER...GENERALLY OVER THE WEST...THE SLIGHTLY SHORTER FETCH SHOULD LIMIT LES POTENTIAL INTO THE ADVISORY RANGE WITH AMOUNTS MAINLY IN THE 2-5 INCH/PER 12 HOUR RANGE. .SHORT TERM...(THURSDAY NIGHT THROUGH WEDNESDAY) .THURSDAY NIGHT THROUGH FRIDAY NIGHT...BY THIS TIME THE CLIPPER SYSTEM THAT BROUGHT LIGHT SNOW AND ISOLATED REPORTS OF FREEZING DRIZZLE THIS MORNING BECOMES ABSORBED BY A STRONGER LOW MOVING INTO NOVA SCOTIA. BEHIND IT...STRONG LAKE EFFECT PROCESSES WILL DEVELOP AS NOTED ABOVE. EXPECT SIGNIFICANT SNOW ACCUMULATIONS AS 850MB TEMPS FALL TO AROUND -18C AND WINDS TURN NORTHERLY BEHIND PREVIOUSLY MENTIONED CLIPPER. DURING THURSDAY NIGHT THE FOCUS FOR THE HEAVIEST SNOW WILL GRADUALLY SHIFT EASTWARD INTO FAR EASTERN MARQUETTE COUNTY...ALGER COUNTY. CURRENT FORECAST CALLS FOR 8 PLUS INCHES OF SNOW FROM SKANDIA EASTWARD TO WETMORE AND MELSTRAND. BY FRIDAY THE OVERALL WIND FIELD BACKS MORE NORTHWESTERLY...AS A RESULT...LAKE EFFECT BANDS WILL SHIFT EVEN MORE EAST...ANOTHER 5 TO 6 INCHES CAN BE EXPECTED EAST OF A LINE FROM DEERTON TO TRENARY. THERE IS SOME CONCERN THAT SLR COULD BE HIGHER THAN THE 25:1 CURRENTLY ANTICIPATED. A QUICK LOOK AT LATEST NAM BUFKIT SOUNDINGS SHOW AN INCREASING SLR TREND THROUGHOUT THE EVENT AS THE BEST LIFT BECOMES BETTER CO-LOCATED WITH THE SNOW GROWTH LAYER. THE COBB SLR METHOD POINTS TO SLR RANGING FROM 15/20:1 TONIGHT AND THURSDAY AND INCREASING TO 30/35:1 BY FRIDAY. OBVIOUSLY SLIGHT CHANGES IN SLR CAN GREATLY AFFECT THE OVERALL TOTAL. FROM TONIGHT THROUGH FRIDAY NIGHT...A STORM TOTAL ACCUMULATION OF UP TO TWO FEET OF SNOW CAN BE EXPECTED ACROSS PORTIONS OF ALGER COUNTY AND FAR EASTERN MARQUETTE COUNTY (EAST OF SKANDIA)...AND A GENERAL FOOT TO FOOT AND A HALF ACROSS THE REST OF NORTHERN MARQUETTE COUNTY...AS WELL AS PORTIONS OF THE WESTERN U.P. FOR ADDITIONAL STORM TOTAL DETAILS SEE THE LATEST WSWMQT PRODUCT. .FRIDAY NIGHT THROUGH MONDAY...LES WILL GRADUALLY DIMINISH THROUGHOUT FRIDAY NIGHT AS SFC HIGH PRESSURE SHIFT INTO THE UPPER GREAT LAKES...IN FACT LES SHOULD BE OVER BEFORE MIDNIGHT ACROSS FAR WESTERN LES NW WIND SNOW BELTS. THIS TEMPORARY LULL IN LES WON/T LAST LONG AS NEXT SYSTEM IS ON OUR DOORSTEP BY SUNDAY NIGHT. LATEST GFS GUIDANCE PROGS A SFC LOW MOVING FROM LAKE WINNIPEG SUNDAY NIGHT TO GEORGIAN BAY BY MONDAY NIGHT. THEREAFTER THE LOW BASICALLY STALLS THROUGH TUESDAY MORNING. THE RESULTING NORTHERLY FLOW WOULD RESULT IN A ANOTHER SUBSTANTIAL LAKE EFFECT SNOW EVENT ON TUESDAY. HOWEVER...THE 00Z ECMWF SOLUTION DEPICTS A MORE SOUTHERLY AND MORE PROGRESSIVE LOW TRACK. THIS WOULD SUGGEST A MINOR LES EVENT AND A MODERATE SYNOPTIC SNOW EVENT AS THE LOW TRACKS DIRECTLY OVER THE U.P. && .AVIATION (FOR THE 00Z TAF ISSUANCE)... LAKE EFFECT SNOW SHOWERS WILL INCREASE THIS EVENING AS COLDER AIR MOVES IN ON NNW WINDS IN THE WAKE OF LOW PRESSURE MOVING SE FROM LAKE SUPERIOR. EXPECT MVFR CONDITIONS AT KCMX TO GIVE WAY TO IFR VSBY THIS EVENING. SIMILARLY...MVFR VSBY AT KSAW EARLY THIS EVENING WILL LOWER TO IFR BY 02-03Z. GUSTY NORTHERLY WINDS WILL ALSO CONTRIBUTE TO BLSN KEEPING VIS IFR OR LOWER INTO THU MORNING. IMPROVEMENT IS EXPECTED THU AFTERNOON AS WINDS BACK SLIGHTLY TO THE NW SHIFTING DOMINANT LES BANDS EAST. && .MARINE (FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)... LOW PRESSURE OVER CNTRL LK SUPERIOR WILL SLIDE SE AND OVER LK HURON BY 06Z THURSDAY. STRONG NORTHERLY WINDS WILL MOVE IN BEHIND THE LOW...WITH GALES TO 35 KNOTS EXPECTED OVER MOST OF LK SUPERIOR. THE STRONGEST WINDS WILL OCCUR OVER THE CENTRAL PORTIONS OF THE LK THIS EVENING...AS PRESSURE RISE COUPLET SLIDES ACROSS THE LAKE. THIS SHOULD PRODUCE GUSTS TO 40 KNOTS BETWEEN ISLE ROYALE AND GRAND MARAIS. WINDS WILL DIMINISH TO 30 KNOTS ON THURS AFTN...AS HIGH PRESSURE MOVES INTO THE NORTHERN PLAINS. WINDS TO 30 KNOTS WILL CONTINUE INTO EARLY FRIDAY MORNING OVER NORTH CENTRAL AND EASTERN LAKE SUPERIOR. WINDS WILL GRADUALLY DIMINISH ON FRIDAY INTO SATURDAY AS THE HIGH MOVES OVER LAKE SUPERIOR. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... LAKE EFFECT SNOW ADVISORY UNTIL 7 AM EST /6 AM CST/ FRIDAY FOR MIZ001>004-009-084. LAKE EFFECT SNOW ADVISORY UNTIL 1 PM EST FRIDAY FOR MIZ085. LAKE EFFECT SNOW WARNING UNTIL 1 PM EST FRIDAY FOR MIZ006. LAKE EFFECT SNOW WARNING UNTIL 10 AM EST FRIDAY FOR MIZ005. LAKE EFFECT SNOW ADVISORY UNTIL 1 PM EST FRIDAY FOR MIZ013. LAKE SUPERIOR... GALE WARNING UNTIL 7 AM EST THURSDAY FOR LSZ267. GALE WARNING UNTIL 4 PM EST THURSDAY FOR LSZ266. GALE WARNING UNTIL 11 AM EST THURSDAY FOR LSZ264-265. GALE WARNING UNTIL 6 AM EST THURSDAY FOR LSZ249-250. GALE WARNING UNTIL 5 AM EST THURSDAY FOR LSZ248. GALE WARNING UNTIL 8 AM EST THURSDAY FOR LSZ243>245. GALE WARNING UNTIL 7 AM EST THURSDAY FOR LSZ263. LAKE MICHIGAN... GALE WARNING UNTIL 10 AM EST THURSDAY FOR LMZ250. && $$ UPDATE...VOSS SYNOPSIS...JLB SHORT TERM...JLB LONG TERM...PEARSON AVIATION...VOSS MARINE...SRF/PEARSON mi AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE MARQUETTE MI 843 PM EST WED NOV 19 2008 .SYNOPSIS... WV IMAGERY AND RUC ANALYSIS INDICATED NW MID/UPPER LEVEL FLOW THROUGH THE NRN PLAINS AND WESTERN GREAT LAKES BTWN A RDG OVER WRN NOAM AND A TROUGH FROM HUDSON BAY THROUGH NRN NEW ENGLAND. A CLIPPER SHORTWAVE TROUGH WAS LOCATED OVER LAKE SUPERIOR WITH ANOTHER UPSTREAM MOVING INTO SRN SASK. AT THE SFC...LOW PRES WAS LOCATED OVER ERN LAKE SUPERIOR WITH A TROUGH TO THE SSE TO NEAR KERY AND THROUGH LAKE MI. SNOW SHOWERS OVER CNTRL UPPER MI WERE ASSOCIATED WITH LOW LEVEL CONV ALONG THE COLD FRONT MOVING IN WITH WINDS VEERING NNW IN ITS WAKE. .SHORT TERM...(TONIGHT AND THURSDAY) ALTHOUGH THE SASK SHRTWV IS EXPECTED TO SLIDE FAR ENOUGH SE OF UPPER MI IT WILL HELP DEEPEN THE ERN CONUS TROUGH AND DRAW COLD AIR OVER NRN ONTARIO AND NRN MANITOBA SOUTHWARD. CAA BEHIND THE FRONT WILL DROP 850 MB TEMPERATURES FROM -8C TO -11 AT 00Z/THU TO -12C TO -16C 12Z/THU AND TO NEAR-17C BY 00Z/FRI...PER NAM/GFS BLEND. WITH LAKE TEMPS AROUND 5C LAKE-850 MB DELTA/T...INSTABILITY WILL BE STRONG ENOUGH (LAKE INDUCED CAPE CLIMBING FROM AROUND 300 J/KG TO 700 J/KG) TO SUPPORT MODERATE TO HEAVY SNOW SHOWERS INTO NNW FLOW SNOWBELTS OFF OF LAKE SUPERIOR. INVERSION HEIGHTS WILL ALSO BE FAVORABLE...IN THE 7K-10K FT RANGE. GOOD SNOWGROWTH PROFILE WITH BULK OF STRONGER CONVECTION OR UPWARD MOTION IN THE LAKE CLOUDS IN THE -12C TO -17C LAYER SHOULD ALSO BOOST SNOW/RATIO TO AROUND 25/1 BY THU. THE LCLY RUN HIGH RES WRF/ARW AND REGIONAL WRF/ARW IN ADDITION TO THE NAM SUGGEST THAT THE STRONGEST AND MOST PERSISTENT LOW LEVEL CONVERGENCE AND HEAVIER SNOWBAND POTENTIAL IS EXPECTED FROM ERN MARQUETTE COUNTY AND THE FAR WRN PORTION OF ALGER COUNTY. BANDS ORIGINATING OFF OF LAKE NIPIGON MAY ALSO LINE UP FROM NEAR KCMX INTO BARAGA COUNTY BEFORE WEAKENING THU. HOWEVER...GENERALLY OVER THE WEST...THE SLIGHTLY SHORTER FETCH SHOULD LIMIT LES POTENTIAL INTO THE ADVISORY RANGE WITH AMOUNTS MAINLY IN THE 2-5 INCH/PER 12 HOUR RANGE. .SHORT TERM...(THURSDAY NIGHT THROUGH WEDNESDAY) .THURSDAY NIGHT THROUGH FRIDAY NIGHT...BY THIS TIME THE CLIPPER SYSTEM THAT BROUGHT LIGHT SNOW AND ISOLATED REPORTS OF FREEZING DRIZZLE THIS MORNING BECOMES ABSORBED BY A STRONGER LOW MOVING INTO NOVA SCOTIA. BEHIND IT...STRONG LAKE EFFECT PROCESSES WILL DEVELOP AS NOTED ABOVE. EXPECT SIGNIFICANT SNOW ACCUMULATIONS AS 850MB TEMPS FALL TO AROUND -18C AND WINDS TURN NORTHERLY BEHIND PREVIOUSLY MENTIONED CLIPPER. DURING THURSDAY NIGHT THE FOCUS FOR THE HEAVIEST SNOW WILL GRADUALLY SHIFT EASTWARD INTO FAR EASTERN MARQUETTE COUNTY...ALGER COUNTY. CURRENT FORECAST CALLS FOR 8 PLUS INCHES OF SNOW FROM SKANDIA EASTWARD TO WETMORE AND MELSTRAND. BY FRIDAY THE OVERALL WIND FIELD BACKS MORE NORTHWESTERLY...AS A RESULT...LAKE EFFECT BANDS WILL SHIFT EVEN MORE EAST...ANOTHER 5 TO 6 INCHES CAN BE EXPECTED EAST OF A LINE FROM DEERTON TO TRENARY. THERE IS SOME CONCERN THAT SLR COULD BE HIGHER THAN THE 25:1 CURRENTLY ANTICIPATED. A QUICK LOOK AT LATEST NAM BUFKIT SOUNDINGS SHOW AN INCREASING SLR TREND THROUGHOUT THE EVENT AS THE BEST LIFT BECOMES BETTER CO-LOCATED WITH THE SNOW GROWTH LAYER. THE COBB SLR METHOD POINTS TO SLR RANGING FROM 15/20:1 TONIGHT AND THURSDAY AND INCREASING TO 30/35:1 BY FRIDAY. OBVIOUSLY SLIGHT CHANGES IN SLR CAN GREATLY AFFECT THE OVERALL TOTAL. FROM TONIGHT THROUGH FRIDAY NIGHT...A STORM TOTAL ACCUMULATION OF UP TO TWO FEET OF SNOW CAN BE EXPECTED ACROSS PORTIONS OF ALGER COUNTY AND FAR EASTERN MARQUETTE COUNTY (EAST OF SKANDIA)...AND A GENERAL FOOT TO FOOT AND A HALF ACROSS THE REST OF NORTHERN MARQUETTE COUNTY...AS WELL AS PORTIONS OF THE WESTERN U.P. FOR ADDITIONAL STORM TOTAL DETAILS SEE THE LATEST WSWMQT PRODUCT. .FRIDAY NIGHT THROUGH MONDAY...LES WILL GRADUALLY DIMINISH THROUGHOUT FRIDAY NIGHT AS SFC HIGH PRESSURE SHIFT INTO THE UPPER GREAT LAKES...IN FACT LES SHOULD BE OVER BEFORE MIDNIGHT ACROSS FAR WESTERN LES NW WIND SNOW BELTS. THIS TEMPORARY LULL IN LES WON/T LAST LONG AS NEXT SYSTEM IS ON OUR DOORSTEP BY SUNDAY NIGHT. LATEST GFS GUIDANCE PROGS A SFC LOW MOVING FROM LAKE WINNIPEG SUNDAY NIGHT TO GEORGIAN BAY BY MONDAY NIGHT. THEREAFTER THE LOW BASICALLY STALLS THROUGH TUESDAY MORNING. THE RESULTING NORTHERLY FLOW WOULD RESULT IN A ANOTHER SUBSTANTIAL LAKE EFFECT SNOW EVENT ON TUESDAY. HOWEVER...THE 00Z ECMWF SOLUTION DEPICTS A MORE SOUTHERLY AND MORE PROGRESSIVE LOW TRACK. THIS WOULD SUGGEST A MINOR LES EVENT AND A MODERATE SYNOPTIC SNOW EVENT AS THE LOW TRACKS DIRECTLY OVER THE U.P. && .AVIATION (FOR THE 00Z TAF ISSUANCE)... LAKE EFFECT SNOW SHOWERS WILL INCREASE THIS EVENING AS COLDER AIR MOVES IN ON NNW WINDS IN THE WAKE OF LOW PRESSURE MOVING SE FROM LAKE SUPERIOR. EXPECT MVFR CONDITIONS AT KCMX TO GIVE WAY TO IFR VSBY THIS EVENING. SIMILARLY...MVFR VSBY AT KSAW EARLY THIS EVENING WILL LOWER TO IFR BY 02-03Z. GUSTY NORTHERLY WINDS WILL ALSO CONTRIBUTE TO BLSN KEEPING VIS IFR OR LOWER INTO THU MORNING. IMPROVEMENT IS EXPECTED THU AFTERNOON AS WINDS BACK SLIGHTLY TO THE NW SHIFTING DOMINANT LES BANDS EAST. && .MARINE (FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)... LOW PRESSURE OVER CNTRL LK SUPERIOR WILL SLIDE SE AND OVER LK HURON BY 06Z THURSDAY. STRONG NORTHERLY WINDS WILL MOVE IN BEHIND THE LOW...WITH GALES TO 35 KNOTS EXPECTED OVER MOST OF LK SUPERIOR. THE STRONGEST WINDS WILL OCCUR OVER THE CENTRAL PORTIONS OF THE LK THIS EVENING...AS PRESSURE RISE COUPLET SLIDES ACROSS THE LAKE. THIS SHOULD PRODUCE GUSTS TO 40 KNOTS BETWEEN ISLE ROYALE AND GRAND MARAIS. WINDS WILL DIMINISH TO 30 KNOTS ON THURS AFTN...AS HIGH PRESSURE MOVES INTO THE NORTHERN PLAINS. WINDS TO 30 KNOTS WILL CONTINUE INTO EARLY FRIDAY MORNING OVER NORTH CENTRAL AND EASTERN LAKE SUPERIOR. WINDS WILL GRADUALLY DIMINISH ON FRIDAY INTO SATURDAY AS THE HIGH MOVES OVER LAKE SUPERIOR. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... LAKE EFFECT SNOW ADVISORY FROM 7 PM EST /6 PM CST/ THIS EVENING TO 7 AM EST /6 AM CST/ FRIDAY FOR MIZ001>004-009-084. LAKE EFFECT SNOW ADVISORY FROM 1 AM THURSDAY TO 1 PM EST FRIDAY FOR MIZ085. LAKE EFFECT SNOW WARNING FROM 7 PM THIS EVENING TO 1 PM EST FRIDAY FOR MIZ006. LAKE EFFECT SNOW WARNING FROM 7 PM THIS EVENING TO 10 AM EST FRIDAY FOR MIZ005. LAKE EFFECT SNOW ADVISORY FROM 7 AM THURSDAY TO 1 PM EST FRIDAY FOR MIZ013. LAKE SUPERIOR... GALE WARNING FROM 1 AM TO 7 AM EST THURSDAY FOR LSZ267. GALE WARNING FROM 8 PM THIS EVENING TO 4 PM EST THURSDAY FOR LSZ266. GALE WARNING FROM 8 PM THIS EVENING TO 11 AM EST THURSDAY FOR LSZ265. GALE WARNING FROM 7 PM THIS EVENING TO 11 AM EST THURSDAY FOR LSZ264. GALE WARNING FROM 9 PM THIS EVENING TO 6 AM EST THURSDAY FOR LSZ249-250. GALE WARNING FROM 9 PM THIS EVENING TO 5 AM EST THURSDAY FOR LSZ248. GALE WARNING FROM 7 PM THIS EVENING TO 8 AM EST THURSDAY FOR LSZ243>245. GALE WARNING FROM 7 PM THIS EVENING TO 7 AM EST THURSDAY FOR LSZ263. LAKE MICHIGAN... GALE WARNING FROM 11 PM THIS EVENING TO 10 AM EST THURSDAY FOR LMZ250. && $$ SYNOPSIS...JLB SHORT TERM...JLB LONG TERM...PEARSON AVIATION...VOSS MARINE...SRF/PEARSON mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN 1103 AM CST THU NOV 20 2008 .AVIATION.../18Z TAF ISSUANCE/ SOME CLOUD COVER CONCERNS OVER THE FIRST SIX HOURS OF THE AVIATION FORECAST... BUT OTHERWISE GENERALLY QUIET THROUGH THE PERIOD. SCATTERED CLOUDS PREDOMINATE AT THE CURRENT TIME IN THE WAKE OF THE SHORTWAVE WHICH MOVED THROUGH EARLIER TODAY... BUT SOME THICKER CLOUDS ASSOCIATED WITH THE LOW LEVEL THERMAL TROUGH ARE EVIDENT TO THE NORTH. THESE WILL ROTATE THROUGH THE AREA THIS AFTERNOON... ALTHOUGH SHOULD THIN TO SOME DEGREE AS THEY DO SO WITH THE LOW LEVEL RIDGE AXIS CONTINUING TO SLIDE EAST INTO THE AREA. HOWEVER... GIVEN THICK NATURE OF THESE CLOUDS AT THE CURRENT TIME... AND THE APPEARANCE OF A CONVERGENCE/VORTICITY AXIS IN THE VISIBLE IMAGERY... THINK THEY WILL HOLD TOGETHER AND IMPACT THE NORTHERN AND EASTERN SITES. SO... WILL KEEP SOME POTENTIAL FOR BKN MVFR CEILINGS DURING THE AFTERNOON HOURS... ALONG WITH A CONTINUATION OF GUSTY NORTHWEST WINDS. ANY CEILINGS SHOULD DISSIPATE TONIGHT AS DRIER AIR WORKS IN ALONG WITH THE SURFACE RIDGE AXIS. WINDS WILL ALSO SUBSIDE... THEN VEER LATE TONIGHT AND ON FRIDAY. THANKS TO CWSU ZMP FOR COLLABORATION... THEIR DISCUSSION IS INCLUDED BELOW. INCLUDED FROM CWSU ZMP... JUST A FEW SC CLOUDS CURRENTLY OVER MSP. EXPECT THAT TO PREVAIL THROUGH THE REST OF THE DAYLIGHT HOURS. SOME LOWER-LEVEL CIGS OVER NORTH MN... BUT EXPECT THOSE CLOUDS TO THIN AS THEY MOVE SOUTHWARD. CAN/T TOTALLY RULE OUT BRIEF BKN CONDS LATER THIS AFTERNOON/EARLY EVENING. AFTER THAT...EXPECT MOSTLY CLEAR THROUGH THE REST OF THE FORECAST PERIOD. HIGH PRESSURE BUILDING IN FROM THE NORTHWEST. RIDGE AXIS MOVING THROUGH FRIDAY MORNING. THE CURRENT GUSTY NW WINDS WILL SUBSIDE TO NEAR CALM TONIGHT. THE GRADUAL WINDSHIFT TO A SOUTHERLY DIRECTION WILL OCCUR DURING THE MORNING HOURS, FRIDAY. WITH THE DRY AIR IN PLACE... NO VSBY RESTRICTIONS EXPECTED. && .PREV DISCUSSION... MAIN ISSUE WITH THE FORECAST UPDATE TODAY IS CLOUD COVER ACROSS THE AREA. THE LATEST VISIBLE IMAGERY SHOWS QUITE A MESS WITH RESPECT TO CLOUD COVER... WITH MOSTLY CLEAR SKIES OVER MUCH OF THE CWFA... AND A BIT MORE CLOUD COVER OVER NORTHERN MINNESOTA. WATER VAPOR IMAGERY AND RUC ANALYSES SHOW A HEALTHY SHORTWAVE JUST SOUTH OF THE AREA... WITH THE CURRENT CLEARING JUST IN THE WAKE OF THAT FEATURE IN A ZONE OF GOOD DNVA. THE CLOUD REDEVELOPMENT TO THE NORTH IS COINCIDENT WITH THE HEART OF THE 925-850MB THERMAL TROUGH... WHICH IS PROGGED TO SLIDE SOUTH AND EAST THROUGH THE DAY. LOW LEVEL RIDGING SHOULD ALSO BE SLIDING EAST THROUGH THE DAY... WORKING TO BRING MORE ANTICYCLONIC FLOW IN AS THE DAY PROGRESSES. ALL IN ALL... WOULD EXPECT TO SEE SOME INCREASE IN CU AS THE DNVA MOVES AWAY AND WE TAKE ADVANTAGE OF A GOOD LOW LEVEL LAPSE RATES CURRENTLY IN PLACE. HOWEVER... GIVEN A GENERAL DECREASE IN LARGE SCALE MOISTURE WHICH IS EXPECTED... OVERCAST CONDITIONS DO NOT SEEM LIKELY TO DEVELOP... WITH MORE OF SCT-BKN CLOUD COVER ANTICIPATED. THE NORTH AND EAST PORTIONS OF THE AREA HAVE THE BEST CHANCE AT SEEING MORE EXTENSIVE CLOUDINESS... SO WILL INCLUDE A BIT MORE THERE... BUT EVERYONE LOOKS TO SEE SOME SUNSHINE THROUGH THE DAY. GIVEN THE GOOD LAPSE RATES DOWN LOW... SOME CHANCE FOR FLURRIES REMAINS... SO WILL RETAIN A MENTION EVERYWHERE BUT THE SOUTHWEST. FORECAST TEMPERATURES STILL LOOK REASONABLE EVEN WITH MORE SUNSHINE EXPECTED GIVEN THE CONTINUED COLD ADVECTION... SO WILL ONLY MAKE MINOR ADJUSTMENTS. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...NONE. WI...NONE. && $$ TRH mn AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN 956 AM CST THU NOV 20 2008 .UPDATE... MAIN ISSUE WITH THE FORECAST UPDATE TODAY IS CLOUD COVER ACROSS THE AREA. THE LATEST VISIBLE IMAGERY SHOWS QUITE A MESS WITH RESPECT TO CLOUD COVER... WITH MOSTLY CLEAR SKIES OVER MUCH OF THE CWFA... AND A BIT MORE CLOUD COVER OVER NORTHERN MINNESOTA. WATER VAPOR IMAGERY AND RUC ANALYSES SHOW A HEALTHY SHORTWAVE JUST SOUTH OF THE AREA... WITH THE CURRENT CLEARING JUST IN THE WAKE OF THAT FEATURE IN A ZONE OF GOOD DNVA. THE CLOUD REDEVELOPMENT TO THE NORTH IS COINCIDENT WITH THE HEART OF THE 925-850MB THERMAL TROUGH... WHICH IS PROGGED TO SLIDE SOUTH AND EAST THROUGH THE DAY. LOW LEVEL RIDGING SHOULD ALSO BE SLIDING EAST THROUGH THE DAY... WORKING TO BRING MORE ANTICYCLONIC FLOW IN AS THE DAY PROGRESSES. ALL IN ALL... WOULD EXPECT TO SEE SOME INCREASE IN CU AS THE DNVA MOVES AWAY AND WE TAKE ADVANTAGE OF A GOOD LOW LEVEL LAPSE RATES CURRENTLY IN PLACE. HOWEVER... GIVEN A GENERAL DECREASE IN LARGE SCALE MOISTURE WHICH IS EXPECTED... OVERCAST CONDITIONS DO NOT SEEM LIKELY TO DEVELOP... WITH MORE OF SCT-BKN CLOUD COVER ANTICIPATED. THE NORTH AND EAST PORTIONS OF THE AREA HAVE THE BEST CHANCE AT SEEING MORE EXTENSIVE CLOUDINESS... SO WILL INCLUDE A BIT MORE THERE... BUT EVERYONE LOOKS TO SEE SOME SUNSHINE THROUGH THE DAY. GIVEN THE GOOD LAPSE RATES DOWN LOW... SOME CHANCE FOR FLURRIES REMAINS... SO WILL RETAIN A MENTION EVERYWHERE BUT THE SOUTHWEST. FORECAST TEMPERATURES STILL LOOK REASONABLE EVEN WITH MORE SUNSHINE EXPECTED GIVEN THE CONTINUED COLD ADVECTION... SO WILL ONLY MAKE MINOR ADJUSTMENTS. && .AVIATION.../12Z TAF ISSUANCE/ BULK OF MVFR CLOUDS AND LOW END VFR CIGS EXTEND ACROSS FAR SW MN INTO EC MN AND WISC... WITH RATHER PATCHY MVFR CLOUDS SCATTERED AROUND NRN MN AND STREAMING SOUTHWARD. RUC SEEMS TO DO THE BEST JOB IN CAPTURING THIS SCENARIO. LOW LEVEL STREAMLINES ARE STILL SOMEWHAT CYCLONIC THROUGH MID AFTERNOON IN EASTERN SITES...MAINLY MSP... EAU AND RNH. THOUGH BEST MOISTURE DROPS INTO SERN MN AFTER 15Z... PROFILES SUGGEST ENOUGH TO MERIT BKN CLOUDS AROUND 3500-4000 WELL INTO THE AFTERNOON. LOW LEVEL LAPSE RATES ARE NOT THAT EXCITING BUT HIGHER LEVELS ARE MORE UNSTABLE. WILL KEEP SOME FLURRIES IN MOST TAFS MIDDAY AND EARLY THIS AFTERNOON WITH REDEVELOPMENT OF BKN SC AFTER A TAD BIT OF HEATING. CLOUDS WILL DISSIPATE AND WINDS DECREASE THIS EVENING AS SFC RIDGE MOVES IN. && .PREV DISCUSSION... /ISSUED 239 AM CST THU NOV 20 2008/ THE CHALLENGES WITH THE FORECAST ARE TEMPS TODAY AND TONIGHT IN THIS COLD PATTERN...THEN MINOR SNOW CHANCES ON FRI NIGHT AND AGAIN DURING THE END OF THE WEEKEND. GOES WV LOOP AND THE LAST EVE 00Z RAOBS DEPICTING SHORT WAVE IN NW FLOW MOVING ACROSS ND AT THE LEADING EDGE OF MUCH COLDER MID-LEVEL TEMPS /-34C H5 TEMP AT CYQD/. ND AND ABR 88DS HAVE INDICATED NUMEROUS ECHOES WITH LIGHT SNOW SHOWERS BEING OBSERVED ALONG FORWARD FLANK OF THIS WAVE. RUC MID-LEVEL LAPSE RATES AND ASSOCIATED TOTAL TOTAL INDICES ALONG WITH MID-LEVEL Q-VECTOR CONVERGENCE LINE UP WELL WITH THIS AREA. THIS WILL TRANSVERSE ACROSS THE SOUTHWEST PORTION OF THE FORECAST AREA THIS MORNING. WITH MOST ND SITES HAVING RECORDED ONLY A TRACE LAST EVE AND THIS MORNING...HAVE CONTINUED WITH ONLY FLURRIES IN THE GRIDS. WITH THE LOWER TO MID TROP TEMPS CONTINUING TO COOL ACROSS THE AREA...BROKEN STRATOCU IS EXPECTED TO FILL IN ANY BREAKS IN CLOUDS ELSEWHERE ACROSS THE AREA. WITH THAT...SCATTERED FLURRIES STILL EXPECTED THIS LATE MORNING AND AFTERNOON ELSEWHERE. WITH SECONDARY SFC COLD FRONT MOVING SOUTH THROUGH THE AREA THIS MORNING...BL COLD AIR ADVECTION IS PREDICTED. SO HAVE TEMPS NEARLY STEADY OR SLIGHTLY FALLING THROUGH THE MORNING...WITH A SLIGHT CLIMB DURING THE EARLY AFTN. WINDS TO STILL BE BREEZY AT TIMES TODAY AS PRESSURE GRADIENT FORCE WILL BE STRONG WITH ARCTIC HIGH BUILDING SOUTHEASTWARD. GOING INTO TONIGHT...TEMPS SHOULD BE IN THE UPPER TEENS TO LOWER 20S NEAR SUNSET...ALLOWING FOR A STARTING POINT NEAR THE AVERAGE MINS FOR THIS TIME OF YEAR. HIGHEST CURRENT SFC PRESSURE UNDER ARCTIC HIGH IN SASKATCHEWAN IS AN IMPRESSIVE 1048 MB. THIS IS EXPECTED TO MODERATE SOMEWHAT BY TONIGHT...BUT BY OVERNIGHT PRESSURES OF OVER 1040 MB EXPECTED INTO WRN CWA. THE WINDS SHOULD COME DOWN QUICKLY IN WRN MN THIS EVE...WHICH WITH CLEARING SKIES SHOULD ALLOW FOR MAXIMUM RADIATIONAL COOLING. H8 TEMPS OVER THE REGION TONIGHT TO BE IN THE -10C TO -16C RANGE. DESPITE NO SNOW ON THE GROUND...GIVEN THOSE TEMP AND MSLP PROJECTIONS...SOME 2F TO 5F MIN TEMPS FRI MORNING ARE VERY POSSIBLE IN WRN MN. CLIPPER SYSTEM FOR FRI NIGHT STILL BEING PROGNOSTICATED TO PASS JUST TO THE SOUTHWEST OF THE FORECAST AREA. BECAUSE THIS IS SO CLOSE TO THE HEELS OF AN EARLY SEASON ARCTIC AIR MASS...THE ASCENT AND MOISTURE IN THE DENDRITIC GROWTH AREA IS GREAT...HOWEVER...THE AREAL COVERAGE AND TIME DURATION OF THIS IS LIMITED AND IS FOCUSED FROM ERN SD INTO NWRN IA. SHOULD BE A FINE CUTOFF TO THE NORTHEAST GIVEN PREDICTED BL TDS AND MODEL SOUNDINGS. SO HAVE TIGHTENED GRADIENT IN POPS OVER MN RIVER VALLEY EVEN MORESO ON FRI NIGHT TO BETTER DEPICT THIS...BUT ANY MINOR SNOW ACCUMULATIONS ARE LOOKING MORE UNLIKELY IN OUR FORECAST AREA. THE NEXT AND POSSIBLY LAST SYSTEM IN NW FLOW TO MOVE DOWN OVER THE UPPER LAKES ON SUNDAY INTO MONDAY. WARM SECTOR OF THIS TO BRING NEAR NORMAL TEMPS FOR SAT AND SUN...WITH HIGHS IN THE 30S TO NEAR 40F. UPPER LEVEL COLD POCKET AND WRAPAROUND MOISTURE STILL APPEAR THE BEST SCENARIO FOR PRECIP ON SUNDAY NIGHT. NOTHING PAINTS TOWARDS ANYTHING GREAT FOR SNOW THOUGH. PRIMARILY NW FLOW STILL EXPECTED TO PREVAIL TOWARDS THE MIDDLE OF THE WEEK BEFORE A POSSIBLE CHANGE TO WRLY OR SWRLY FLOW. STILL SOME INCONSISTENCIES WITH THIS...AND THE 00Z ECMWF KEEPS NORTHWEST FLOW WITH A CLIPPER- LIKE SYSTEM FOR THANKSGIVING. WE SHALL SEE...BUT DOES LOOK LIKE WRN U.S. RIDGE SHOULD EVOLVE GRADUALLY EASTWARD INTO DEC. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...NONE. WI...NONE. && $$ TRH/TDK/MTF mn AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN 542 AM CST THU NOV 20 2008 .UPDATE... UPDATED FOR AVIATION DISCUSSION BELOW. && .DISCUSSION... /ISSUED 239 AM CST THU NOV 20 2008/ THE CHALLENGES WITH THE FORECAST ARE TEMPS TODAY AND TONIGHT IN THIS COLD PATTERN...THEN MINOR SNOW CHANCES ON FRI NIGHT AND AGAIN DURING THE END OF THE WEEKEND. GOES WV LOOP AND THE LAST EVE 00Z RAOBS DEPICTING SHORT WAVE IN NW FLOW MOVING ACROSS ND AT THE LEADING EDGE OF MUCH COLDER MID-LEVEL TEMPS /-34C H5 TEMP AT CYQD/. ND AND ABR 88DS HAVE INDICATED NUMEROUS ECHOES WITH LIGHT SNOW SHOWERS BEING OBSERVED ALONG FORWARD FLANK OF THIS WAVE. RUC MID-LEVEL LAPSE RATES AND ASSOCIATED TOTAL TOTAL INDICES ALONG WITH MID-LEVEL Q-VECTOR CONVERGENCE LINE UP WELL WITH THIS AREA. THIS WILL TRANSVERSE ACROSS THE SOUTHWEST PORTION OF THE FORECAST AREA THIS MORNING. WITH MOST ND SITES HAVING RECORDED ONLY A TRACE LAST EVE AND THIS MORNING...HAVE CONTINUED WITH ONLY FLURRIES IN THE GRIDS. WITH THE LOWER TO MID TROP TEMPS CONTINUING TO COOL ACROSS THE AREA...BROKEN STRATOCU IS EXPECTED TO FILL IN ANY BREAKS IN CLOUDS ELSEWHERE ACROSS THE AREA. WITH THAT...SCATTERED FLURRIES STILL EXPECTED THIS LATE MORNING AND AFTERNOON ELSEWHERE. WITH SECONDARY SFC COLD FRONT MOVING SOUTH THROUGH THE AREA THIS MORNING...BL COLD AIR ADVECTION IS PREDICTED. SO HAVE TEMPS NEARLY STEADY OR SLIGHTLY FALLING THROUGH THE MORNING...WITH A SLIGHT CLIMB DURING THE EARLY AFTN. WINDS TO STILL BE BREEZY AT TIMES TODAY AS PRESSURE GRADIENT FORCE WILL BE STRONG WITH ARCTIC HIGH BUILDING SOUTHEASTWARD. GOING INTO TONIGHT...TEMPS SHOULD BE IN THE UPPER TEENS TO LOWER 20S NEAR SUNSET...ALLOWING FOR A STARTING POINT NEAR THE AVERAGE MINS FOR THIS TIME OF YEAR. HIGHEST CURRENT SFC PRESSURE UNDER ARCTIC HIGH IN SASKATCHEWAN IS AN IMPRESSIVE 1048 MB. THIS IS EXPECTED TO MODERATE SOMEWHAT BY TONIGHT...BUT BY OVERNIGHT PRESSURES OF OVER 1040 MB EXPECTED INTO WRN CWA. THE WINDS SHOULD COME DOWN QUICKLY IN WRN MN THIS EVE...WHICH WITH CLEARING SKIES SHOULD ALLOW FOR MAXIMUM RADIATIONAL COOLING. H8 TEMPS OVER THE REGION TONIGHT TO BE IN THE -10C TO -16C RANGE. DESPITE NO SNOW ON THE GROUND...GIVEN THOSE TEMP AND MSLP PROJECTIONS...SOME 2F TO 5F MIN TEMPS FRI MORNING ARE VERY POSSIBLE IN WRN MN. CLIPPER SYSTEM FOR FRI NIGHT STILL BEING PROGNOSTICATED TO PASS JUST TO THE SOUTHWEST OF THE FORECAST AREA. BECAUSE THIS IS SO CLOSE TO THE HEELS OF AN EARLY SEASON ARCTIC AIR MASS...THE ASCENT AND MOISTURE IN THE DENDRITIC GROWTH AREA IS GREAT...HOWEVER...THE AREAL COVERAGE AND TIME DURATION OF THIS IS LIMITED AND IS FOCUSED FROM ERN SD INTO NWRN IA. SHOULD BE A FINE CUTOFF TO THE NORTHEAST GIVEN PREDICTED BL TDS AND MODEL SOUNDINGS. SO HAVE TIGHTENED GRADIENT IN POPS OVER MN RIVER VALLEY EVEN MORESO ON FRI NIGHT TO BETTER DEPICT THIS...BUT ANY MINOR SNOW ACCUMULATIONS ARE LOOKING MORE UNLIKELY IN OUR FORECAST AREA. THE NEXT AND POSSIBLY LAST SYSTEM IN NW FLOW TO MOVE DOWN OVER THE UPPER LAKES ON SUNDAY INTO MONDAY. WARM SECTOR OF THIS TO BRING NEAR NORMAL TEMPS FOR SAT AND SUN...WITH HIGHS IN THE 30S TO NEAR 40F. UPPER LEVEL COLD POCKET AND WRAPAROUND MOISTURE STILL APPEAR THE BEST SCENARIO FOR PRECIP ON SUNDAY NIGHT. NOTHING PAINTS TOWARDS ANYTHING GREAT FOR SNOW THOUGH. PRIMARILY NW FLOW STILL EXPECTED TO PREVAIL TOWARDS THE MIDDLE OF THE WEEK BEFORE A POSSIBLE CHANGE TO WRLY OR SWRLY FLOW. STILL SOME INCONSISTENCIES WITH THIS...AND THE 00Z ECMWF KEEPS NORTHWEST FLOW WITH A CLIPPER- LIKE SYSTEM FOR THANKSGIVING. WE SHALL SEE...BUT DOES LOOK LIKE WRN U.S. RIDGE SHOULD EVOLVE GRADUALLY EASTWARD INTO DEC. && .AVIATION.../12Z TAF ISSUANCE/ BULK OF MVFR CLOUDS AND LOW END VFR CIGS EXTEND ACROSS FAR SW MN INTO EC MN AND WISC... WITH RATHER PATCHY MVFR CLOUDS SCATTERED AROUND NRN MN AND STREAMING SOUTHWARD. RUC SEEMS TO DO THE BEST JOB IN CAPTURING THIS SCENARIO. LOW LEVEL STREAMLINES ARE STILL SOMEWHAT CYCLONIC THROUGH MID AFTERNOON IN EASTERN SITES...MAINLY MSP... EAU AND RNH. THOUGH BEST MOISTURE DROPS INTO SERN MN AFTER 15Z... PROFILES SUGGEST ENOUGH TO MERIT BKN CLOUDS AROUND 3500-4000 WELL INTO THE AFTERNOON. LOW LEVEL LAPSE RATES ARE NOT THAT EXCITING BUT HIGHER LEVELS ARE MORE UNSTABLE. WILL KEEP SOME FLURRIES IN MOST TAFS MIDDAY AND EARLY THIS AFTERNOON WITH REDEVELOPMENT OF BKN SC AFTER A TAD BIT OF HEATING. CLOUDS WILL DISSIPATE AND WINDS DECREASE THIS EVENING AS SFC RIDGE MOVES IN. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...NONE. WI...NONE. && $$ MTF/TDK mn AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN 239 AM CST THU NOV 20 2008 .DISCUSSION... THE CHALLENGES WITH THE FORECAST ARE TEMPS TODAY AND TONIGHT IN THIS COLD PATTERN...THEN MINOR SNOW CHANCES ON FRI NIGHT AND AGAIN DURING THE END OF THE WEEKEND. GOES WV LOOP AND THE LAST EVE 00Z RAOBS DEPICTING SHORT WAVE IN NW FLOW MOVING ACROSS ND AT THE LEADING EDGE OF MUCH COLDER MID-LEVEL TEMPS /-34C H5 TEMP AT CYQD/. ND AND ABR 88DS HAVE INDICATED NUMEROUS ECHOES WITH LIGHT SNOW SHOWERS BEING OBSERVED ALONG FORWARD FLANK OF THIS WAVE. RUC MID-LEVEL LAPSE RATES AND ASSOCIATED TOTAL TOTAL INDICES ALONG WITH MID-LEVEL Q-VECTOR CONVERGENCE LINE UP WELL WITH THIS AREA. THIS WILL TRANSVERSE ACROSS THE SOUTHWEST PORTION OF THE FORECAST AREA THIS MORNING. WITH MOST ND SITES HAVING RECORDED ONLY A TRACE LAST EVE AND THIS MORNING...HAVE CONTINUED WITH ONLY FLURRIES IN THE GRIDS. WITH THE LOWER TO MID TROP TEMPS CONTINUING TO COOL ACROSS THE AREA...BROKEN STRATOCU IS EXPECTED TO FILL IN ANY BREAKS IN CLOUDS ELSEWHERE ACROSS THE AREA. WITH THAT...SCATTERED FLURRIES STILL EXPECTED THIS LATE MORNING AND AFTERNOON ELSEWHERE. WITH SECONDARY SFC COLD FRONT MOVING SOUTH THROUGH THE AREA THIS MORNING...BL COLD AIR ADVECTION IS PREDICTED. SO HAVE TEMPS NEARLY STEADY OR SLIGHTLY FALLING THROUGH THE MORNING...WITH A SLIGHT CLIMB DURING THE EARLY AFTN. WINDS TO STILL BE BREEZY AT TIMES TODAY AS PRESSURE GRADIENT FORCE WILL BE STRONG WITH ARCTIC HIGH BUILDING SOUTHEASTWARD. GOING INTO TONIGHT...TEMPS SHOULD BE IN THE UPPER TEENS TO LOWER 20S NEAR SUNSET...ALLOWING FOR A STARTING POINT NEAR THE AVERAGE MINS FOR THIS TIME OF YEAR. HIGHEST CURRENT SFC PRESSURE UNDER ARCTIC HIGH IN SASKATCHEWAN IS AN IMPRESSIVE 1048 MB. THIS IS EXPECTED TO MODERATE SOMEWHAT BY TONIGHT...BUT BY OVERNIGHT PRESSURES OF OVER 1040 MB EXPECTED INTO WRN CWA. THE WINDS SHOULD COME DOWN QUICKLY IN WRN MN THIS EVE...WHICH WITH CLEARING SKIES SHOULD ALLOW FOR MAXIMUM RADIATIONAL COOLING. H8 TEMPS OVER THE REGION TONIGHT TO BE IN THE -10C TO -16C RANGE. DESPITE NO SNOW ON THE GROUND...GIVEN THOSE TEMP AND MSLP PROJECTIONS...SOME 2F TO 5F MIN TEMPS FRI MORNING ARE VERY POSSIBLE IN WRN MN. CLIPPER SYSTEM FOR FRI NIGHT STILL BEING PROGNOSTICATED TO PASS JUST TO THE SOUTHWEST OF THE FORECAST AREA. BECAUSE THIS IS SO CLOSE TO THE HEELS OF AN EARLY SEASON ARCTIC AIR MASS...THE ASCENT AND MOISTURE IN THE DENDRITIC GROWTH AREA IS GREAT...HOWEVER...THE AREAL COVERAGE AND TIME DURATION OF THIS IS LIMITED AND IS FOCUSED FROM ERN SD INTO NWRN IA. SHOULD BE A FINE CUTOFF TO THE NORTHEAST GIVEN PREDICTED BL TDS AND MODEL SOUNDINGS. SO HAVE TIGHTENED GRADIENT IN POPS OVER MN RIVER VALLEY EVEN MORESO ON FRI NIGHT TO BETTER DEPICT THIS...BUT ANY MINOR SNOW ACCUMULATIONS ARE LOOKING MORE UNLIKELY IN OUR FORECAST AREA. THE NEXT AND POSSIBLY LAST SYSTEM IN NW FLOW TO MOVE DOWN OVER THE UPPER LAKES ON SUNDAY INTO MONDAY. WARM SECTOR OF THIS TO BRING NEAR NORMAL TEMPS FOR SAT AND SUN...WITH HIGHS IN THE 30S TO NEAR 40F. UPPER LEVEL COLD POCKET AND WRAPAROUND MOISTURE STILL APPEAR THE BEST SCENARIO FOR PRECIP ON SUNDAY NIGHT. NOTHING PAINTS TOWARDS ANYTHING GREAT FOR SNOW THOUGH. PRIMARILY NW FLOW STILL EXPECTED TO PREVAIL TOWARDS THE MIDDLE OF THE WEEK BEFORE A POSSIBLE CHANGE TO WRLY OR SWRLY FLOW. STILL SOME INCONSISTENCIES WITH THIS...AND THE 00Z ECMWF KEEPS NORTHWEST FLOW WITH A CLIPPER- LIKE SYSTEM FOR THANKSGIVING. WE SHALL SEE...BUT DOES LOOK LIKE WRN U.S. RIDGE SHOULD EVOLVE GRADUALLY EASTWARD INTO DEC. && .AVIATION.../06Z TAF ISSUANCE/ NOT MUCH CHANGE OVERNIGHT WITH EXTENSIVE MVFR CEILINGS OVER THE UPPER MIDWEST PERSISTING THROUGH 17Z THURSDAY. SOME IMPROVEMENT OCCURRING OVER MOST OF THE TAF SITES BY NOON AS CEILING AND CLOUD HEIGHTS RISE BETWEEN 3K TO 5K FEET AGL AS THE SFC HIGH PRES RIDGE BUILDS OVER THE UPPER MIDWEST THROUGH THE PERIOD. BECOMING VFR OVER ENTIRE FORECAST AREA BY MID/LATE EVENING THURSDAY. PRESSURE GRADIENT STILL REMAIN MODERATELY STRONG DURING THE DAY ON THURSDAY WITH UNIFORM WIND DIRECTION ALOFT...WIND SPEED TO STAY UP THROUGHOUT THE DAY. THIS SHOULD ALSO HELP ERODE THE LOW CLOUDS AND PRODUCE SIGNIFICANT BREAKS DURING THE AFTERNOON. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...NONE. WI...NONE. && $$ MTF/JVM mn AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE DULUTH MN 1007 PM CST WED NOV 19 2008 .UPDATE... WE INCREASED OVERNIGHT LOW TEMPERATURES IN NORTHWEST WISCONSIN...AS CLOUDS WILL HANG ON MUCH LONGER. THE COLDEST TEMPERATURES WILL OCCUR IN THE BORDERLAND...WHERE SOME CLEARING HAS OCCURRED...THOUGH HOW COLD IT DIPS WILL DEPEND ON HOW QUICKLY THE LOW CLOUDS ERODE...AND HOW FAR SOUTH THE CLEARING LINE GETS. WE ALSO DECREASED POPS DURING THE LATE EVENING IN NORTHWEST WISCONSIN...THOUGH KEPT THEM UP OVERNIGHT...AS HI RES RUC HAS PRECIP MOVING IN FROM THE EAST...INCREASING IN COVERAGE AFTER ABOUT 3 AM. AS OF NOW...LIGHT SNOW IS ONLY OCCURRING/BEEN REPORTED IN IRON COUNTY...AND IT HAS AMOUNTED TO VERY LITTLE...DUE TO QUITE A BIT OF BLOWING AND DRIFTING OF SNOW. AN OBSERVER IN GILE REPORTED MAYBE UP TO A QUARTER OF AN INCH SO FAR. THE BEST CHANCE FOR LAKE EFFECT SNOW CONTINUES TO BE TOMORROW LATE MORNING THROUGH THE DAY...AS INVERSION HEIGHTS RISE...THE BEST LIFT BECOMES CO-LOCATED WITH THE DENDRITE PRODUCTION ZONE...AND 850 TO 700 MB MOISTURE RETURNS. ADDITIONALLY...A QUICK MOVING BAND OF SNOW SHOWERS IS MOVING THROUGH ON THE TRAILING EDGE OF THE LOW CLOUDS THROUGH NORTHEAST MINNESOTA. WHILE NOT LOOKING LIKE MUCH ON RADAR...SOME OF THIS SNOW IS STICKING TO THE GROUND...AS INDICATED BY A SPOTTER IN INTERNATIONAL FALLS. A QUICK TENTH OR TWO IS POSSIBLE TONIGHT. && .PREV DISCUSSION... /ISSUED 255 PM CST WED NOV 19 2008/ DISCUSSION... SHORT TERM FCST FOCUS ON ARRIVAL OF ARCTIC AIR MASS AND LES AMOUNTS ALONG THE SOUTH SHORE OF LAKE SUPERIOR. NO CHANGES TO BE MADE TO CURRENT LES HEADLINES WHICH ARE IN EFFECT THIS EVENING THROUGH THURSDAY NIGHT. THE WRN GRT LAKES REGION WILL REMAIN SITUATED BETWEEN SFC LOW TO THE E AND BUILDING HIGH PRESSURE FROM THE W OVER THE NEXT 36 HRS. THIS WILL SUSTAIN THE GUSTY NW WINDS THROUGH THURSDAY EVENING...WEAKENING BY FRI MORNING AS THE SFC RIDGE REACHES ERN MN/WRN WIS. THE COLD AIR WILL KEEP FLURRIES OR ISOLD -SHSN OVER THE FA...WITH LITTLE OR NO ACCUMULATION. THE EXCEPTION WILL BE ACROSS NRN WIS WHERE A NRLY FETCH AND STEEP LAPSE RATES WILL PRODUCE CONDITIONS FAVORABLE FOR LES...LATE TODAY THROUGH EARLY FRIDAY MORNING. THIS WILL BE A PROLONGED SN EVENT OVER A 36 HR PERIOD. SIGNIFICANT SNOWFALL TOTALS ARE EXPECTED OF GENERALLY AROUND 10 INCHES ALONG THE HIGHER TERRAIN AND GOGEBIC RANGE OF NRN WIS...WITH ISOLATED HIGHER AMOUNTS OF A FOOT OR MORE POSSIBLE. AREAS INLAND OR SHELTERED FORM THE LAKE EFFECT...AS ASHLAND...CAN EXPECT STORM TOTALS ON THE ORDER OF 2 TO 3 INCHES. ALTHOUGH DELTA T VALUES AND FORCING SUPPORT MODERATE TO HEAVY SNOWFALL AMOUNTS...SOME CONCERN IN THE H70-H50 DRY POCKET THAT IS CURRENTLY DEPICTED ON THE VIS SAT AS CLR SKIES OVER SRN MANITOBA/WRN ONTARIO. THE NAM 850-700 RH FIELD SHOWS THIS DRY LAYER SINKS S OVER NRN MN AND WRN LK SUPERIOR OVERNIGHT...JUST AS THE COLDEST AIR SETTLES OVERHEAD. ALTHOUGH SFC-850 MB LAYER REMAINS SATURATED AND INSTABILITY IS IN PLACE...SOME FEAR THAT THIS DRY AIR MAY SINK FAR ENOUGH INTO THE LO LVLS TO RESULT IN A DECREASE IN INTENSITY OR A TOTAL LULL IN SNOWFALL...MAINLY DURING THE 10-18Z THURS TIME FRAME. TO ACCOUNT FOR THIS POSSIBILITY WILL MENTION THE SHSN MAY WEAKEN OR END FOR A SHORT TIME IN THE WSW PRODUCT...BUT ATTM THREAT IS NOT ENOUGH TO MAKE SIG CHANGES TO STORM TOTAL SN AMOUNTS. THE NAM SHOWS THAT THE MID LVL MOISTURE DOES REBOUND BY THURSDAY AFTRN...SO WOULD EXPECT THE LES TO REGENERATE AND PRODUCE A FEW MORE INCHES OF ACCUM LATE THURS/THURS NIGHT...BEFORE THE HIGH PRESSURE SHUTS IT OFF FOR GOOD FRI MORNING. THE NAM SHOWS THAT THE MID LVL MOISTURE DOES REBOUND BY THURSDAY AFTRN...SO WOULD EXPECT THE LES TO REGENERATE AND PRODUCE A FEW MORE INCHES OF ACCUM BEFORE THE HIGH PRESSURE SHUTS IT OFF FOR GOOD FRI MORNING. AVIATION...GUSTY WINDS BEHIND AN ARCTIC COLD FRONT WILL SLOWLY DIMINISH THROUGH THUR AFTERNOON...THOUGH REMAIN GUSTY AT TIMES THROUGH THE TAF PD. BKN TO OVC MVFR CIGS WILL SCATTER OUT FROM NORTH TO SOUTH THIS EVE...AS HIGH PRES BEGINS TO RIDGE INTO THE UPPER MIDWEST FROM CANADA. SCT SNOW SHOWERS AND FLURRIES WILL TAPER OFF BY LATE THIS AFTERNOON. && POINT TEMPS/POPS... DLH 13 21 5 21 / 30 10 10 10 INL 5 13 1 17 / 30 10 10 10 BRD 16 22 5 23 / 10 10 10 10 HYR 19 19 4 20 / 40 30 10 10 ASX 19 20 12 20 / 70 60 70 30 && .DLH WATCHES/WARNINGS/ADVISORIES... MN...NONE. WI...LAKE EFFECT SNOW WARNING UNTIL 6 AM CST FRIDAY FOR ASHLAND-IRON. LAKE EFFECT SNOW ADVISORY UNTIL MIDNIGHT CST THURSDAY NIGHT FOR BAYFIELD. LS...SMALL CRAFT ADVISORY UNTIL 6 AM CST FRIDAY FOR LSZ121-LSZ140- LSZ145-LSZ146-LSZ147-LSZ148. SMALL CRAFT ADVISORY UNTIL 4 PM CST THURSDAY FOR LSZ141-LSZ142- LSZ143-LSZ144. $$ DONOFRIO/GSF mn AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE JACKSON MS 1052 AM CST THU NOV 20 2008 .DISCUSSION...RUC ANALYSIS INDICATES 1025MB HIGH PRESSURE AT THE SURFACE LOCATED ALONG THE MS GULF COAST. THIS WILL CONTINUE TO SLIDE SOUTH AND A COLD FRONT WILL PUSH INTO OUR REGION THIS AFTERNOON. CURRENTLY...THE FRONT IS LOCATED GENERALLY ALONG A LINE FROM MONTICELLO ARKANSAS...TO GREENVILLE MISSISSIPPI TO COLUMBUS. WINDS BEHIND THE FRONT HAVE BEEN ABOUT 15-18KT WITH BRIEF HIGHER GUSTS UP TO 20 KTS. AHEAD OF THE FRONT...LOW CLOUDS FROM THIS MORNING HAVE BEEN A LITTLE SLOW TO BURN OFF ALONG THE MISSISSIPPI RIVER BUT EXPECT SUNNY SKIES TO RETURN TO THIS AREA TODAY. SUNNY SKIES HAVE ALLOWED TEMPERATURES TO WARM UP RATHER QUICKLY OVER CENTRAL AND SOUTHERN MISSISSIPPI. READINGS ALONG AND SOUTH OF THE INTERSTATE 20 CORRIDOR HAVE BEEN RUNNING ROUGHLY 7-9 DEGREES WARMER THAN ANTICIPATED AND DECIDED TO BUMP HIGHS ABOUT 2-4 DEGREES WARMER TODAY. EXPECT FRONTAL PASSAGE THROUGH CENTRAL MISSISSIPPI GENERALLY AROUND 18-20Z AND HAVE ADJUSTED WINDS ACCORDINGLY. OTHERWISE...ADJUSTED HOURLY TEMPS TO ACCOUNT FOR OBSERVATIONAL TRENDS. REST OF THE FORECAST LOOKS ON TRACK AND UPDATED ZONES WILL BE OUT SHORTLY. /28/ && .AVIATION...REMAINING STRATUS/FOG DECK OVER W CENTRAL MS/NERN LA ERODING RATHER QUICKLY AHEAD OF COLD FRONT. VFR CONDITIONS WILL GENERALLY PREVAIL AT ALL TAF SITES THROUGH FRIDAY WITH THE POSSIBLE EXCEPTION OF A 4-5HR PERIOD BEHIND THE FROPA WHEN CAA STRATOCU FIELD COULD DEVELOP BETWEEN 2-3K FEET. THE WIND SHIFT TO THE NORTH ASSOCIATED WITH THE FRONT OF 12-18KTS WITH GUSTS OF 25-30KTS POSSIBLE THROUGH THIS EVENING. THE WINDS SHOULD DIMINISH TO LESS THAN 10KTS AFTER ABOUT 10Z FRIDAY MORNING. /40/ && .PRELIMINARY POINT TEMPS/POPS... JACKSON 68 34 49 24 / 0 0 0 0 MERIDIAN 67 30 49 20 / 0 0 0 0 VICKSBURG 66 35 49 27 / 0 0 0 0 HATTIESBURG 72 35 52 25 / 0 0 0 0 NATCHEZ 71 36 51 27 / 0 0 0 0 GREENVILLE 58 32 48 25 / 0 0 0 0 GREENWOOD 58 31 47 24 / 0 0 0 0 && .JAN WATCHES/WARNINGS/ADVISORIES... MS...NONE. LA...NONE. AR...NONE. && $$ 28/40 ms AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE HASTINGS NE 1046 PM CST WED NOV 19 2008 .AVIATION...06Z KGRI TAF...STRATUS ERODED QUICKLY ACROSS THE AREA THIS EVENING...WITH STRATUS STILL LINGERING ACROSS NORTHERN AND EASTERN NEBRASKA AT THIS TIME. CURRENT SATELLITE TRENDS SUGGEST MOSTLY CLEAR SKIES SHOULD PERSIST AT THE KGRI TERMINAL THROUGH EARLY MORNING THURSDAY...BEFORE CLOUDS BEGIN BUILDING BACK IN TOWARDS SUNRISE THURSDAY. CEILINGS ACROSS NORTHERN AND EASTERN NEBRASKA ARE GENERALLY IN THE 3000-4000 FT AGL RANGE AND FEEL THIS WILL BE THE CEILING LEVEL WHEN CLOUDS REINTRODUCE THEMSELVES TO KGRI ON THURSDAY. AS A RESULT...HAVE OPTED TO GO WITH VFR CONDITIONS THROUGH THE PERIOD. NO VISIBILITY RESTRICTIONS ARE EXPECTED...WITH WINDS REMAINING OUT OF THE NORTH THROUGH LATE THURSDAY. && .PREV DISCUSSION... /ISSUED 1018 PM CST WED NOV 19 2008/ UPDATE...STRATUS HAS DIMINISHED OVER MUCH OF SOUTH CENTRAL NEBRASKA AND NORTH CENTRAL KANSAS THIS EVENING. ALTHOUGH MODEL GUIDANCE REMAINS WAY OFF WITH RESPECT TO CLOUD COVER...RUC SEEMS TO HAVE A HANDLE ON STRATUS ACROSS FAR EASTERN NEBRASKA AND PORTIONS OF IOWA. CURRENT SATELLITE TRENDS INDICATE CLEAR SKIES TO PERSIST THROUGH EARLY MORNING THURSDAY...WITH THE RUC SUGGESTING CLOUDS MAY BUILD BACK IN FROM THE NORTH AND NORTHEAST TOWARDS SUNRISE THURSDAY. WENT AHEAD AND BACKED WAY OFF ON CLOUD COVER THROUGH EARLY MORNING THURSDAY...BEFORE BRINGING BACK CLOUDS HEADING INTO THE DAY THURSDAY. ALSO DROPPED OVERNIGHT LOWS A FEW DEGREES FOR TONIGHT AS LACK OF CLOUD COVER AND RELATIVELY LIGHT WINDS WILL PROMOTE FURTHER RADIATIVE COOLING. PREV DISCUSSION... /ISSUED 642 PM CST WED NOV 19 2008/ UPDATE...SURGE OF COLD AIR PUSHING INTO THE AREA MORE QUICKLY THAN ANTICIPATED AND HAVE UPDATED HOURLY TEMPERATURE GRIDS AS A RESULT. DID NOT ADJUST OVERNIGHT LOWS AS THOSE STILL APPEAR GOOD. PREV DISCUSSION... /ISSUED 250 PM CST WED NOV 19 2008/ SHORT TERM...TONIGHT THROUGH THURSDAY NIGHT. A REINFORCING SHOT OF COLD AIR WILL SWEEP THROUGH THE CWA THIS EVENING FUNNELING COLD CANADIAN AIR DOWN INTO THE CENTRAL PLAINS. THERE WAS A PRETTY GOOD SPREAD IN TEMPERATURES ACROSS THE STATE AT 2 PM...RANGING FROM THE LOWER TO MID 30S AT ONEIL IN NORTH CENTRAL NEBRASKA...TO THE LOWER 60S IN SOUTH CENTRAL NEBRASKA. COLD AIR WILL SLIDE INTO THE CWA ALL NIGHT LONG ALLOWING TEMPERATURES TO DROP INTO THE 20S. THERE SHOULD BE A GOOD DEAL OF CLOUD COVER TOMORROW AND EXPECT TEMPERATURES WILL STRUGGLE TO REACH BACK INTO THE 30S TO MAYBE AROUND 40 FOR AFTERNOON HIGHS. THERE WILL BE SOME MODEST MID LEVEL FRONTOGENETICAL FORCING TOMORROW MORNING THAT COULD RESULT IN A FLURRY OR TWO. HOWEVER...THERE ARE A FEW DRY LAYERS IN THE PROFILE THAT WILL BE DIFFICULT TO SATURATE AND OVERALL MOISTURE WITH THIS AIRMASS IS LIMITED. THEREFORE...EVEN SEEING A FEW FLURRIES MAY BE A BIT OF A STRETCH. COULD SEE SOME CLEARING SKIES THURSDAY NIGHT THAT ALONG WITH DECREASING WINDS SHOULD PROMOTE GOOD RADIATIONAL COOLING. CONSEQUENTLY...OVERNIGHT LOWS THURSDAY NIGHT SHOULD FALL INTO THE UPPER TEENS IN MANY LOCATIONS. LONG TERM...12Z FRIDAY THROUGH WEDNESDAY. MAIN FORECAST CONCERN WILL BE TEMPERATURES. AN UPPER LEVEL LOW WILL MOVE TO THE NORTH OF THE FORECAST AREA FRIDAY AND FRIDAY NIGHT. THE BEST ENERGY AND MOISTURE REMAINS TO THE NORTH OF THE FORECAST AREA SO EXPECT THAT THE PRECIPITATION SHOULD ALSO STAY NORTH. WILL HAVE TO WATCH THIS SYSTEM SINCE LATER MODEL RUNS ARE BRINGING IT A LITTLE FURTHER SOUTH WHICH WOULD BRING SOME PRECIPITATION INTO THE NORTHERN PART OF THE FORECAST AREA. TEMPERATURES SHOULD REMAIN ON THE COOL SIDE UNTIL THE UPPER LOW MOVES TO THE EAST. BY LATE FRIDAY NIGHT AND INTO SATURDAY THERE IS WARM ADVECTION AND TEMPERATURES SHOULD START TO WARM BACK UP SOME. EARLY SUNDAY ANOTHER COLD FRONT MOVES THROUGH THE AREA. THIS ONE HAS LESS COLD AIR BEHIND IT AND THE TEMPERATURES ON SUNDAY CONTINUE TO BE AT OR A LITTLE ABOVE AVERAGE. ANOTHER UPPER WAVE MOVES THROUGH BEHIND THE COLD FRONT AND PRECIPITATION DEVELOPS TO THE SOUTHEAST OF THE FORECAST AREA ALONG THE FRONT SUNDAY NIGHT. ONCE AGAIN WE SHOULD REMAIN DRY. BY LATE MONDAY NIGHT WARM ADVECTION STARTS UP AGAIN AND A SHORT WAVE RIDGE BUILDS INTO THE AREA WITH A SLIGHT WARMING TREND FOR TUESDAY AND WEDNESDAY. && .GID WATCHES/WARNINGS/ADVISORIES... NE...NONE. KS...NONE. && $$ ne AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE HASTINGS NE 1018 PM CST WED NOV 19 2008 .UPDATE...STRATUS HAS DIMINISHED OVER MUCH OF SOUTH CENTRAL NEBRASKA AND NORTH CENTRAL KANSAS THIS EVENING. ALTHOUGH MODEL GUIDANCE REMAINS WAY OFF WITH RESPECT TO CLOUD COVER...RUC SEEMS TO HAVE A HANDLE ON STRATUS ACROSS FAR EASTERN NEBRASKA AND PORTIONS OF IOWA. CURRENT SATELLITE TRENDS INDICATE CLEAR SKIES TO PERSIST THROUGH EARLY MORNING THURSDAY...WITH THE RUC SUGGESTING CLOUDS MAY BUILD BACK IN FROM THE NORTH AND NORTHEAST TOWARDS SUNRISE THURSDAY. WENT AHEAD AND BACKED WAY OFF ON CLOUD COVER THROUGH EARLY MORNING THURSDAY...BEFORE BRINGING BACK CLOUDS HEADING INTO THE DAY THURSDAY. ALSO DROPPED OVERNIGHT LOWS A FEW DEGREES FOR TONIGHT AS LACK OF CLOUD COVER AND RELATIVELY LIGHT WINDS WILL PROMOTE FURTHER RADIATIVE COOLING. && .PREV DISCUSSION... /ISSUED 642 PM CST WED NOV 19 2008/ UPDATE...SURGE OF COLD AIR PUSHING INTO THE AREA MORE QUICKLY THAN ANTICIPATED AND HAVE UPDATED HOURLY TEMPERATURE GRIDS AS A RESULT. DID NOT ADJUST OVERNIGHT LOWS AS THOSE STILL APPEAR GOOD. PREV DISCUSSION... /ISSUED 508 PM CST WED NOV 19 2008/ AVIATION...00Z KGRI TAF...A SURGE OF COLD AIR ACROSS THE NORTHERN AND CENTRAL PLAINS IS PUSHING A STRATUS DECK TOWARDS THE KGRI TERMINAL AT THIS HOUR. VFR CONDITIONS WILL PERSIST AT KGRI UNTIL THIS DECK REACHES THE AREA AROUND 02Z...AT WHICH TIME CONDITIONS WILL DETERIORATE RAPIDLY INTO MVFR CONDITIONS. MVFR CONDITIONS WILL HOLD STRONG THROUGH MUCH OF THE DAY THURSDAY BEFORE VFR CONDITIONS RESUME BY LATE THURSDAY. NO VISIBILITY RESTRICTIONS EXPECTED THROUGH THE FORECAST PERIOD. NORTHERLY SURFACE WINDS WILL GUST TO NEAR 25 KTS EARLY IN THE PERIOD BEFORE DIMINISHING BY 04Z. PREV DISCUSSION... /ISSUED 250 PM CST WED NOV 19 2008/ SHORT TERM...TONIGHT THROUGH THURSDAY NIGHT. A REINFORCING SHOT OF COLD AIR WILL SWEEP THROUGH THE CWA THIS EVENING FUNNELING COLD CANADIAN AIR DOWN INTO THE CENTRAL PLAINS. THERE WAS A PRETTY GOOD SPREAD IN TEMPERATURES ACROSS THE STATE AT 2 PM...RANGING FROM THE LOWER TO MID 30S AT ONEIL IN NORTH CENTRAL NEBRASKA...TO THE LOWER 60S IN SOUTH CENTRAL NEBRASKA. COLD AIR WILL SLIDE INTO THE CWA ALL NIGHT LONG ALLOWING TEMPERATURES TO DROP INTO THE 20S. THERE SHOULD BE A GOOD DEAL OF CLOUD COVER TOMORROW AND EXPECT TEMPERATURES WILL STRUGGLE TO REACH BACK INTO THE 30S TO MAYBE AROUND 40 FOR AFTERNOON HIGHS. THERE WILL BE SOME MODEST MID LEVEL FRONTOGENETICAL FORCING TOMORROW MORNING THAT COULD RESULT IN A FLURRY OR TWO. HOWEVER...THERE ARE A FEW DRY LAYERS IN THE PROFILE THAT WILL BE DIFFICULT TO SATURATE AND OVERALL MOISTURE WITH THIS AIRMASS IS LIMITED. THEREFORE...EVEN SEEING A FEW FLURRIES MAY BE A BIT OF A STRETCH. COULD SEE SOME CLEARING SKIES THURSDAY NIGHT THAT ALONG WITH DECREASING WINDS SHOULD PROMOTE GOOD RADIATIONAL COOLING. CONSEQUENTLY...OVERNIGHT LOWS THURSDAY NIGHT SHOULD FALL INTO THE UPPER TEENS IN MANY LOCATIONS. LONG TERM...12Z FRIDAY THROUGH WEDNESDAY. MAIN FORECAST CONCERN WILL BE TEMPERATURES. AN UPPER LEVEL LOW WILL MOVE TO THE NORTH OF THE FORECAST AREA FRIDAY AND FRIDAY NIGHT. THE BEST ENERGY AND MOISTURE REMAINS TO THE NORTH OF THE FORECAST AREA SO EXPECT THAT THE PRECIPITATION SHOULD ALSO STAY NORTH. WILL HAVE TO WATCH THIS SYSTEM SINCE LATER MODEL RUNS ARE BRINGING IT A LITTLE FURTHER SOUTH WHICH WOULD BRING SOME PRECIPITATION INTO THE NORTHERN PART OF THE FORECAST AREA. TEMPERATURES SHOULD REMAIN ON THE COOL SIDE UNTIL THE UPPER LOW MOVES TO THE EAST. BY LATE FRIDAY NIGHT AND INTO SATURDAY THERE IS WARM ADVECTION AND TEMPERATURES SHOULD START TO WARM BACK UP SOME. EARLY SUNDAY ANOTHER COLD FRONT MOVES THROUGH THE AREA. THIS ONE HAS LESS COLD AIR BEHIND IT AND THE TEMPERATURES ON SUNDAY CONTINUE TO BE AT OR A LITTLE ABOVE AVERAGE. ANOTHER UPPER WAVE MOVES THROUGH BEHIND THE COLD FRONT AND PRECIPITATION DEVELOPS TO THE SOUTHEAST OF THE FORECAST AREA ALONG THE FRONT SUNDAY NIGHT. ONCE AGAIN WE SHOULD REMAIN DRY. BY LATE MONDAY NIGHT WARM ADVECTION STARTS UP AGAIN AND A SHORT WAVE RIDGE BUILDS INTO THE AREA WITH A SLIGHT WARMING TREND FOR TUESDAY AND WEDNESDAY. && .GID WATCHES/WARNINGS/ADVISORIES... NE...NONE. KS...NONE. && $$ ne AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BINGHAMTON NY 125 PM EST WED NOV 19 2008 .SYNOPSIS... LAKE EFFECT SNOW SHOWERS WILL SLOWLY TAPER OFF TODAY. A COLD FRONT WILL SWING THROUGH TONIGHT, BRINGING ANOTHER ROUND OF SNOW TO NY AND PA. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... AS OF 1210PM...HAVE UPDATED TO DROP LES ADVISORY AS OF NOON AS ACCUMULATING SNOWS WILL SOON END...ALTHOUGH LATE MORNING REFLECTIVITY RETURNS SUGGEST SOME CAYUGA/SKANEATELES LAKE ENHANCEMENT WITH PERHAPS ANOTHER FLUFFY INCH IN A FEW DOWNWIND LOCATIONS. THE FLOW WILL GAIN AN INCREASINGLY WESTERLY COMPONENT THIS AFTERNOON...WHICH SHOULD PUSH THE REMNANT SHSN/FLURRIES EAST AND GIVEN GOOD LLEVEL LAPSE RATES...WE SHOULD SEE THE CONVECTION BECOME MORE CELLULAR WITH TIME. HAVE ALSO LOWERED TEMPS A FEW DEGREES BASED ON LATE MORNING TRENDS...AND THE FACT THAT LOCATIONS ALONG THE I81 CORRIDOR HAVE NOT SEEN MUCH SUN THIS MORNING. UPDATED PRODUCTS/GRIDS ARE OUT. AS OF 840AM...ONE PRIMARY BAND OF LAKE EFFECT CONTINUES THIS MORNING...CENTERED BETWEEN CORTLAND AND ITHACA...SOUTH INTO NE PA ALONG THE BRADFORD/SUSQUEHANNA COUNTY LINE. BGM VWP THIS MORNING SHOWS A PRETTY PERSISTENT NNW FLOW...AND THE 12Z RAOB FROM KBUF INDICATES INVERSION HEIGHTS DECREASING...BUT STILL AROUND 825 MB. SHORT TERM NAM/RUC GUIDANCE SUGGESTS THAT THROUGH THE MORNING HOURS...THE FLOW WILL NOT CHANGE APPRECIABLY IN THE BL AND THIS IS SUPPORTED BY CURRENT MSAS ANALYSIS WHICH INDICATE VERY LITTLE IN THE WAY OF SURFACE PRESSURE CHANGES IN THE LAST FEW HOURS. THE FLOW WILL WEAKEN...HOWEVER...AS THE H85 RIDGE CRESTS OVERHEAD...SO THE BAND SHOULD PULL BACK TOWARDS THE LAKE SHORE BY LATE MORNING...WITH WEAKENING/DISSIPATION AS THE FLOW GOES WEAK WESTERLY THIS AFTERNOON. HAVE ADJUSTED POPS SOME TO ACCOUNT FOR THIS AND HAVE ALSO CANCELLED THE ADVISORY FOR THE WESTERN HALF OF THE COUNTIES THAT WERE IN IT OVERNIGHT GIVEN THAT ACCUMULATING SNOWS WILL NOT PUSH BACK TO THE WEST THIS MORNING. EXPIRATION TIME OF THE REMAINING ADV IS NOON...WHICH LOOKS GREAT AND WILL LIKELY UPDATE AGAIN AS WE NEAR THAT POINT. OTHERWISE...ONLY MINOR TWEAKS AS GRIDS LOOK TO BE IN GOOD SHAPE. UPDATED PRODUCTS/GRIDS ARE ON THE STREET. PREVIOUS DISCUSSION FOLLOWS... MULTIBAND LES CONTINUES THIS MORNING IN NNW FLOW OFF OF ONTARIO, WITH ENHANCEMENT SOUTH OF THE FINGER LAKES. WILL KEEP CURRENT ADVISORY AS IS, AND FEEL THE BEST ACCUMS WILL BE FINGER LAKE ENHANCED FROM TOMPKINS COUNTY DOWN THROUGH TIOGA COUNTY NY. WINDS WILL BEGIN TO SHIFT TODAY AHEAD OF NEXT SYSTEM, CUTTING OFF THE LAKE FLOW. && .SHORT TERM /6 PM THIS EVENING THROUGH FRIDAY NIGHT/... IMPRESSIVE COLD SHOT TO FOLLOW WITH CLIPPER SYSTEM TONIGHT AND THURSDAY. WHILE THE LOWER ATMOSPHERE REMAINS DRY, THERE IS A GOOD DEAL OF LIFT WITH THIS SYSTEM. ALSO LAKE MOISTURE SHOULD AID THE PRECIP AMOUNTS AS NORTHWESTERLY WINDS WHIP ACROSS ONTARIO AND ERIE. WILL FORECAST 1 TO 3 INCHES OF SNOW MAINLY WEST OF I-81, WITH LESSER AMOUNTS EAST. ONCE THE CLIPPER MOVES THROUGH, THE POLAR AIR IS RELOADED. THIS WILL KEEP TEMPERATURES MUCH BELOW NORMAL AND WINTER-LIKE. THE COLD AIR FLOWING ACROSS THE WARM LAKE WATERS WILL ACTIVATE LES ONCE MORE, WITH LAKE SNOW SHOWERS FORECAST TO FALL THROUGH AT LEAST FRIDAY NIGHT. AT NO POINT DOES THE INSTABILITY LOOK STRONG ENOUGH TO SUGGEST A MAJOR EVENT. HOWEVER IT SHOULD BE RATHER PERSISTENT FOR THE END OF THE WORK WEEK. && .LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/... AN UNSETTLED PERIOD...WITH BELOW NORMAL TEMPERATURES...IS EXPECTED TO CONTINUE THROUGH AT LEAST MUCH OF NEXT WEEK. GENERAL MODEL AGREEMENT ABOUT AN ANCHORED EASTERN U.S. TROUGH THROUGHOUT THE PERIOD. DETAIL DIFFERENCES IN EXACTLY HOW THIS TROUGH AMPLIFIES/RE-LOADS EARLY NEXT WEEK LEAD TO OBVIOUS MODEL TO MODEL DISCREPANCIES IN HOW MUCH PRECIPITATON OCCURS FROM MONDAY ONWARD. FOR NOW...WE`LL CONTINUE WITH THE IDEA THAT LAKE-EFFECT SNOWS WILL WIND DOWN DURING THE LATTER PART OF THE WEEKEND. AFTER THIS BRIEF LULL...THINGS GET MORE ACTIVE AGAIN FROM LATER MONDAY THROUGH THE MIDDLE OF NEXT WEEK...AS A STORM SYSTEM MAY TRY TO ORGANIZE NEAR THE EAST COAST. DUE TO MUCH UNCERTAINTY THIS FAR OUT...WE`LL RETAIN OUR CHANCES FOR AT LEAST SOME LIGHT SNOWFALL/SNOW SHOWERS WELL INTO NEXT WEEK. && .AVIATION /18Z WEDNESDAY THROUGH MONDAY/... BRIEF MVFR RESTRICTIONS STILL POSSIBLE THROUGH LATE AFTERNOON AT KBGM AND KITH...AS A WEAKENING LAKE SNOW BAND REMAINS IN THE VICINITY. OTHERWISE...LOOK FOR VFR TO PERSIST THROUGH LATE TONIGHT. AFTER MIDNIGHT AND INTO THURSDAY (ROUGHLY 06Z TO 15Z)...A FAST MOVING DISTURBANCE WILL CROSS THE REGION...PERHAPS BRINGING SOME LIGHT SNOW. AT THIS JUNCTURE...IT LOOKS LIKE VFR WILL HOLD FOR MUCH OF THE TIME. HOWEVER...THE BEST CHANCE FOR RESTRICTIONS (MVFR) LOOK TO BE AT KELM AND KITH. NORTHWEST WINDS 5-10 KT THIS AFTERNOON...WILL BECOME LIGHT SOUTHERLY TONIGHT...THEN SOUTHWEST TO WEST AT 5-10 KT THURSDAY. OUTLOOK... LATE THURSDAY NIGHT THROUGH SATURDAY...LOCALIZED MVFR/IFR POSSIBLE...AS LAKE-EFFECT SNOW BANDS DEVELOP OVER THE REGION. SUNDAY INTO MONDAY...IMPROVEMENT BACK TO VFR FORESEEN. && .BGM WATCHES/WARNINGS/ADVISORIES... PA...NONE. NY...NONE. && $$ SYNOPSIS...DJP NEAR TERM...DJP/JMA SHORT TERM...DJP LONG TERM...MLJ AVIATION...MLJ ny AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RALEIGH NC 645 AM EST THU NOV 20 2008 .SYNOPSIS... HIGH PRESSURE WILL CONTINUE PUSHING TO OUR SOUTH THROUGH TODAY... AS A POLAR FRONT DROPS SOUTHWARD THROUGH THE REGION. THIS WILL BRING TEMPERATURES WELL BACK BELOW NORMAL FOR FRIDAY INTO THE WEEKEND. && .NEAR TERM /THROUGH TONIGHT/... AS OF 145 AM THURSDAY... THROUGH TODAY: UP FIRST IS THE BANK OF WARM ADVECTION CLOUDS UP AROUND 700 MB OVER THE NORTHEAST CWA. THESE CLOUDS WERE ACTUALLY PICKED UP ON BY YESTERDAY`S MODELS BETTER THAN THE LATEST RUNS... AND THE SHALLOW NATURE OF THIS CLOUD DECK LIKELY HAS MUCH TO DO WITH THE MODELS` POOR DETECTION OF IT. THE LATEST MODELS KICK THE 700 MB WARM FRONT TO THE ENE AND TAKE THESE CLOUDS WITH IT IN THE COUPLE OF HOURS... ALTHOUGH THE LATEST RUC IS SEVERAL HOURS SLOWER AND AGREES BETTER WITH OBSERVED TRENDS. WILL HANG ONTO MOSTLY CLOUDY SKIES EARLY THIS MORNING IN THE FAR NE CWA WITH A QUICK IMPROVING TREND SOON AFTER SUNRISE. ELSEWHERE SHOULD SEE A GOOD BIT OF SUNSHINE THIS MORNING. THEN... OUR EYES DRIFT TO THE COLD FRONT DUE TO DROP THROUGH NC THIS AFTERNOON. FRONTAL PASSAGE SHOULD BE RATHER UNEVENTFUL... AND WE SHOULD ACTUALLY SEE A PREFRONTAL TROUGH PASSAGE WITH SURFACE WINDS SHIFTING TO WNW BEFORE THE MAIN SLUG OF COLD AIR ARRIVES WITH PASSAGE OF THE POLAR FRONT... NOW STRETCHING ACROSS WI AND IA... LATE IN THE DAY FORECAST SOUNDINGS AND CONDITIONS IMMEDIATELY UPSTREAM INDICATE LITTLE CLOUDINESS IN OUR AREA UNTIL AFTER DARK. LOW LEVEL THICKNESSES HEAD UP OVER 1330 M ACROSS THE SOUTHERN CWA THIS AFTERNOON... AND HAVE BUMPED UP HIGHS HERE TO THE UPPER 50S TO NEAR 60. READINGS SHOULD MAX OUT IN THE MID 50S ACROSS THE NORTH AS IS CURRENTLY FORECASTED... AND THIS MATCHES WELL WITH LOCAL HIGH TEMPERATURE TOOLS BUT IS A COUPLE DEGREES ABOVE STATISTICAL GUIDANCE. FOR TONIGHT: THIS IS LOOKING TO BE A MUCH CLOUDIER PERIOD THAN EARLIER THOUGHT... AND THE RISK OF A FLURRY OR TWO APPEARS TO BE ON THE RISE... IF WE CAN GET ENOUGH LIFT. FORECAST SOUNDINGS... PARTICULARLY THE GFS... SHOW NEAR SATURATION IN A DEEP LAYER FROM AROUND 800 MB UP THROUGH 550 MB DROPPING THROUGH THE CWA FROM 04Z TO 12Z. LOOKING AT SATELLITE IMAGERY AND 00Z SOUNDINGS OVER SD... THIS VERTICAL AND AREAL EXTENT OF MOISTURE CERTAINLY LOOKS PLAUSIBLE. THE GFS IN PARTICULAR RAMPS UP THE LIFT NICELY TOO... AS IT BRINGS THE MID LEVEL VORTICITY MAXIMUM (NOW PUSHING INTO ND) A BIT FARTHER SOUTH INTO NRN NC AND FASTER (BEFORE 12Z) AS COMPARED TO THE NAM. UPPER JET FORCING ALSO LOOKS TO INCREASE AS THE RIGHT ENTRANCE REGION OF THE 120+ KT JET IS EVIDENT OVER NC ON BOTH THE NAM AND GFS. CONSIDERING THAT THE MOISTURE WILL SPAN THE DEPTH OF THE PRIME CRYSTAL GROWTH ZONE... AND GIVEN THAT THE VERTICAL WET BULB PROFILE WILL BE ALL BELOW FREEZING... A FEW FLURRIES ARE POSSIBLE TONIGHT... MAINLY AFTER MIDNIGHT. THE DRYNESS OF THE SUBCLOUD LAYER SHOULD HOLD IT TO NOTHING MORE THAN FLURRIES... AND TONIGHT WE`LL BE LACKING THE LOW LEVEL INSTABILITY THAT WE SAW ON TUESDAY THAT HELPED PRODUCE CONVECTIVE SNOW SHOWERS THEN. ANY FLURRIES SHOULD BE GONE BY AROUND SUNRISE AS THE MID LEVELS DRY OUT QUICKLY. HAVE INCHED LOWS UP A BIT ESPECIALLY IN THE SOUTHEAST... AND WE NOW HAVE LOWS OF 29-34. -GIH && .SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/... AS OF 225 AM THURSDAY... FOR FRIDAY/FRIDAY NIGHT: FORECAST IN ONE WORD... COLD. THE MID LEVEL TROUGH AXIS EXITS THE COAST EARLY IN THE DAY... AND A POLAR SOURCE SURFACE HIGH BUILDS IN FROM THE WNW. 850 MB TEMPERATURES HEAD DOWN BELOW -10C AGAIN... AND LOW LEVEL THICKNESSES BOTTOM OUT BELOW 1270 METERS LATE FRIDAY/FRIDAY NIGHT. WE SHOULD SEE PLENTY OF SUNSHINE FRIDAY WITH ONLY A FEW FLAT STRATOCU EXPECTED WITH HEATING... BUT THIS SHOULD DO LITTLE TO TEMPER THE STRONG COLD AIR ADVECTION. EXPECT HIGHS OF 40-46. BRISK WINDS AROUND 15 MPH ARE LIKELY AND MAY GUST UP TO 25-30 MPH IF WE CAN FULLY TAP UP THROUGH THE MIXED LAYER. WINDS WILL SUBSIDE TOWARD SUNSET... AND WHILE THEY WILL BE LIGHT THROUGH THE NIGHT... THEY SHOULD NOT GO COMPLETELY CALM. BUT EVEN SO... WITH THESE ANOMALOUSLY LOW THICKNESSES AND WITH SURFACE DEW POINTS WELL DOWN INTO THE TEENS TO NEAR 10F... LOWS AROUND 20 TO THE LOWER 20S ARE LIKELY SATURDAY MORNING. RDU`S RECORD LOW COULD BE THREATENED BUT GSO`S IS SAFER (SEE CLIMATE SECTION BELOW). A FEW UPPER TEENS IN SHELTERED AREAS ARE ALMOST A CERTAINTY. FOR SATURDAY/SATURDAY NIGHT: THE SURFACE HIGH SETTLES OVERHEAD AND THE 850 MB ANTICYCLONE DRIFTS OVERHEAD DURING THIS PERIOD. BUT FARTHER ALOFT... WHAT IS NOW A STRONG LOW PUSHING INTO THE PACIFIC NORTHWEST DIVES QUICKLY TO THE ESE... DAMPENING INTO AN OPEN WAVE AS IT APPROACHES NC. BUT NEVERTHELESS THIS SHOULD STILL BRING IN APPRECIABLE MID AND HIGH CLOUDINESS SPREADING INTO NC SATURDAY AFTERNOON FROM THE NW... AND NAM/GFS FORECAST SOUNDINGS ARE IN GOOD AGREEMENT ON THIS. HAVE RAISED SKY COVER THROUGH SATURDAY INTO THE EVENING. THICKNESSES START TO REBOUND AS THE 850 MB WARM FRONT HEADS TO OUR NE AND HIGHS SHOULD BE A DEGREE OR TWO WARMER... HARDLY NOTICEABLE THOUGH GIVEN THE FRIGID START TO THE DAY. CLOUD COVER SHOULD DECREASE SATURDAY NIGHT AS THE CLIPPER SHORTWAVE TROUGH EXITS. FORECAST LOWS IN THE LOW-MID 20S STILL LOOK GOOD. -GIH && .LONG TERM /SUNDAY THROUGH WEDNESDAY/... AS OF 255 AM THURSDAY... FOR SUNDAY/SUNDAY NIGHT: QUIET WEATHER FOR SUNDAY WITH SURFACE HIGH PRESSURE OVER THE EASTERN CAROLINAS AND BROAD (BUT WEAK) RIDGING IN THE MID LEVELS. THICKNESSES REBOUND INTO THE 1290-1300 METER RANGE... STILL WELL BELOW NORMAL HOWEVER... AND WE SHOULD SEE HIGHS STILL ABOUT 2 CATEGORIES BELOW NORMAL... 51-56. OUR NEXT WEATHER SYSTEM OF INTEREST... A POLAR VORTEX... DROPS INTO THE UPPER MIDWEST SUNDAY NIGHT... AND MID LEVEL FLOW INTO THE APPALACHIANS STARTS TO BECOME CYCLONIC AND STRENGTHENS... AS THE SURFACE HIGHS SHIFTS OFFSHORE. WE SHOULD SEE INCREASING HIGH CLOUDS THROUGH THE NIGHT BUT THIS SHOULD HAVE LITTLE IMPACT ON RADIATIONAL COOLING. EXPECT LOWS 26-32. FOR MONDAY THROUGH WEDNESDAY: THE LATEST GFS AND ECMWF RUNS HAVE COME INTO SLIGHTLY BETTER AGREEMENT ON THE TIMING OF THE COLD FRONT THROUGH THE CWA MONDAY NIGHT AND ITS ASSOCIATED PRECIP. WILL SHOW INCREASING CLOUDS MONDAY AFTERNOON AND HIGHS OF 54-61 AS THICKNESSES ACTUALLY APPROACH NORMAL. WILL RAISE POPS A BIT MONDAY NIGHT TO GOOD CHANCE. LOWS 35-40. THE 00Z/20 ECMWF THEN BECOMES A LITTLE STRONGER AND FARTHER SOUTH WITH THE VORTEX... TRACKING IT ACROSS WV TO DELMARVA BY LATE TUESDAY... WHILE THE 00Z/20 GFS TAKES A PA/NJ TRACK... ALTHOUGH BOTH SHOW A NEGATIVE TILT. WILL MAKE NO SIGNIFICANT CHANGES BEYOND MONDAY NIGHT... HOLDING ONTO THE EXIT OF POPS TUESDAY MORNING AND A DROP BACK DOWN TO BELOW NORMAL TEMPERATURES. -GIH && .AVIATION /12Z THURSDAY THROUGH MONDAY/... AS OF 645 AM THURSDAY... VFR CONDITIONS THROUGH THE TAF PERIOD. CLEAR SKIES SHOULD PREVAIL THROUGH MOST OF THE DAY. A FRONTAL SYSTEM APPROACHING FROM THE WEST WILL USHER SOME MID LEVEL CLOUDS INTO THE REGION TONIGHT THROUGH EARLY FRIDAY (09-10Z)... MAINLY ACROSS THE NORTHWEST AND NORTH CENTRAL REGION...INT/GSO/RDU... LINGERING OVER THE EAST AND SOUTH ...FAY AND RWI THROUGH ABOUT 12Z. AS A SURFACE TROUGH MOVES THROUGH THE AREA... LIGHT SOUTHWEST WINDS WILL SHIFT TO THE WEST AND INCREASE TO 5 TO 10 MPH. AFTER A FRONTAL PASSAGE TONIGHT THROUGH EARLY FRIDAY... WINDS WILL SHIFT TO THE NORTHWEST. VFR CONDITIONS ARE EXPECTED FRIDAY THROUGH MONDAY AS HIGH PRESSURE TAKES FIRM CONTROL OF CENTRAL NORTH CAROLINAS WEATHER. GUSTY WINDS AT 25 TO 30 MPH WILL BE POSSIBLE FRIDAY AFTERNOON... TAPERING OFF BY EARLY SATURDAY. && .CLIMATE... RECORD LOWS FOR NOVEMBER 22: RDU....23 (1987) GSO....17 (2000) && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...HARTFIELD NEAR TERM...HARTFIELD SHORT TERM...HARTFIELD LONG TERM...HARTFIELD AVIATION...RHJ CLIMATE...GIH nc AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BISMARCK ND 901 PM CST THU NOV 20 2008 .UPDATE... CURRENTLY...SURFACE HIGH IS SITUATED OVER EASTERN NORTH DAKOTA. WITH CLEAR SKIES OVER ALL BUT THE FAR SOUTHWEST...TEMPERATURES HAVE DROPPED OFF QUICKLY. DAY SHIFT INDICATED THIS MAY BE A PROBLEM AND HAD ALREADY LOWERED MINIMUM TEMPERATURES OVER THE EASTERN CWA. IT APPEARS WE WILL HAVE TO DROP THEM A BIT MORE...WITH CURRENT TEMPERATURES ONLY A FEW DEGREES FROM OVERNIGHT FORECAST LOWS. WENT AROUND 5 BELOW FROM EASTERN BOTTINEAU AND NORTHERN PIERCE...NORTH AND EAST THROUGH ROLETTE COUNTY. WE WILL NEED TO CUT TEMPERATURES FARTHER WEST (CENTRAL ND) ALSO...AS THERE IS LITTLE CLOUD COVER THIS EVENING. SOUTHERLY RETURN FLOW IS PICKING UP IN THE FAR WEST...SO DO NOT EXPECT TEMPERATURES TO FALL OFF TOO MUCH THERE. LOOKING AT THE LATEST RUC...AND 18Z GFS/NAM/ECMWF...IT LOOKS LIKE MODELS ARE HAVING A HARD TIME BRINGING PRECIPITATION INTO THE FAR WEST BEFORE 12Z. LATEST SATELLITE AND RADAR LOOPS ARE INDICATING MOSTLY CLEAR SKIES OVER MUCH OF EASTERN MONTANA WITH LITTLE IN THE WAY OF CLOUD COVER UNTIL YOU GET WEST OF HAVRE AND BILLINGS. 18Z NAM BUFR SOUNDINGS ARE SHOWING VERY DRY LOWER ATMOSPHERE OVER THE WEST THROUGH 12Z. THEREFORE...THINK WE CAN GET RID OF THE SLIGHT CHANCE POPS IN THE FAR WEST OVERNIGHT. && .PREV DISCUSSION... /ISSUED 255 PM CST THU NOV 20 2008/ SHORT TERM...TONIGHT THROUGH SUNDAY NIGHT SHORT TERM MODELS IN DECENT AGREEMENT AND NOT A LOT OF CHANGES TO ONGOING GRID PACKAGE. BUMPED SOME POPS DOWN ON SUNDAY AS MOISTURE AND LIFT ARE SOMEWHAT LIMITED AND DOWNGRADED TO FLURRIES IN MY EAST. STAYED SLIGHT CHANCE POPS IN COORDINATION WITH WESTERN NEIGHBORS. ENERGY FROM BAY OF ALASKA LOW NOW OVER WESTERN WASHINGTON AND OREGON FORECAST TO REACH THE WESTERN PLAINS BY FRIDAY MORNING. ALL MODELS IN AGREEMENT WITH BAND OF HEAVIEST SNOW OVER SOUTHWEST AND SOUTH CENTRAL NORTH DAKOTA BUT HPC QPF AND WINTER WEATHER DESKS HAVE BACKED OFF A BIT WITH ACCUMULATIONS WITH ONLY 1 PLUS OVER THAT REGION. HAVE PULLED BACK A BIT IN AGREEMENT BUT SNOWFALL TOTALS WILL STILL ROUND TO 2 INCHES IN PLACES AND THAT SEEMS POSSIBLE. WEAK PRESSURE FALLS AHEAD OF NEXT SYSTEM WILL SWING WINDS TO THE SOUTHEAST...HOWEVER MAIN ENERGY AND LIFT REMAIN NORTH OF BORDER ESPECIALLY ON NAM MODEL SOLUTION. DROPPED SLIGHT CHANCE PORTIONS NORTHEAST TO FLURRIES BUT TO REMAIN IN COORDINATION WITH WESTERN NEIGHBORS LEFT SLIGHT CHANCE THERE...THIS MAY BE REVISITED WITH NEXT MODEL RUN. LONG TERM...MONDAY THROUGH THURSDAY NIGHT GFS AND EUROPEAN AGAIN LOOKING SIMILAR IN THE BEGINNING OF THE EXTENDED PERIOD. MONDAY WILL SEE THE BUILDING OF AN UPPER LEVEL RIDGE OVER NORTH DAKOTA AS A LOW EXITS THE REGION TO THE GREAT LAKES AND EASTERN NORTH AMERICA. A MORE ZONAL WEST-TO-EAST FLOW OVER NORTH DAKOTA ON TUESDAY AS A SHORTWAVE MOVES ACROSS CENTRAL CANADA. THE MODELS BEGIN TO DIVERGE ON WEDNESDAY/THURSDAY. THIS MORNING`S EUROPEAN MODEL DEVELOPS A WEAK SHORTWAVE IN THE FLOW OF THE WESTERLIES THAT MOVES EAST QUICKLY ACROSS SOUTHERN/CENTRAL CANADA. THE GFS HOWEVER DIGS A STRONGER SHORTWAVE AND DEVELOPS IT FARTHER SOUTH - ACROSS SOUTHERN SASKATCHEWAN AND THE DAKOTAS/MINNESOTA. THE HYDROMET PREDICTION CENTER FAVORS A BLEND OF THE GFS AND EUROPEAN...AND MENTIONED A MORE NORTHERLY TRACK OF THIS SYSTEM IS PREFERRED. WILL KEEP THE FORECAST DRY FOR NOW...WITH SUCH UNCERTAINTY IN PLACEMENT OF A STORM SYSTEM FOR DAYS 6/7. IF FUTURE MODEL RUNS ARE CONSISTENT WITH THE FEATURE AND DEVELOP IT FARTHER SOUTH...THEN LATER FORECASTS WILL LIKELY SHOW A CHANCE OF SNOW FOR WEDNESDAY NIGHT/THURSDAY. OTHERWISE...HIGHS IN THE 30S AND 40S. LOWS IN THE TEENS AND 20S. AVIATION... COOL SURFACE HIGH FROM SOUTH CENTRAL CANADA WILL CONTINUE TO MOVE SOUTH/SOUTHEAST INTO THE DAKOTAS AND MINNESOTA. MVFR BROKEN CLOUDS OVER CENTRAL/EASTERN NORTH DAKOTA ASSOCIATED WITH AN EXITING UPPER LEVEL SHORTWAVE ARE EXPECTED TO DECREASE GRADUALLY FROM WEST TO EAST. SOME SNOW SHOWERS WITH 3-5 MILES VSBYS WILL BE SCATTERED ACROSS CENTRAL NORTH DAKOTA THROUGH LATE AFTERNOON AND ACROSS EASTERN NORTH DAKOTA THROUGH EARLY EVENING. THEN CLEARING SKIES ALL AREAS UNTIL AFTER 09-12Z WHEN THE NEXT LOW PRESSURE SYSTEM DEVELOPS OVER WYOMING TONIGHT AND BRINGS MVFR AND IFR CIGS AND VSBYS WITH SNOW TO SOUTHWESTERN NORTH DAKOTA FRIDAY MORNING SPREADING TO CENTRAL ND FRIDAY AFTERNOON. && .BIS WATCHES/WARNINGS/ADVISORIES... NONE. && $$ TWH nd AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GRAND FORKS ND 944 AM CST WED NOV 19 2008 .DISCUSSION... CURRENT VISIBLE SATELLITE SHOWING SOME BREAKS IN CLOUD COVER ACROSS WESTERN ONTARIO...EXTENDING DOWN INTO LOW COUNTY. WITH STRONG CAA...DO NOT EXPECT MUCH IMPACT ON TEMPS AS THEY WILL STILL REMAIN MOSTLY CLOUDY ALL DAY. SEEING SOME SNOW REPORTS AS FAR WEST AS HALLOCK...SO CURRENT WX/POP GRIDS STILL LOOK GOOD. MAX TEMPS HAVE PRETTY MUCH OCCURRED ACROSS THE FA...AND CURRENT TEMP TRENDS USING RUC GUIDANCE IS WORKING OUT WELL. MOST SIGNIFICANT CHANGE TO GRIDS THIS MORNING WILL BE BUMPING UP 15Z SKY COVER TO 100 PER CENT AND TRENDING DOWN TO MOSTLY CLOUDY THROUGHOUT THE DAY. WILL SEND UPDATED GRIDS/ZONES BY 10 AM. && .AVIATION... EXPECT MVFR OVC DECK TO SLOWLY SEE SOME BREAKS THROUGH OOZ. NORTHEAST FA SHOULD BEGIN TO BREAK UP EARLIEST...AS EVIDENT ON CURRENT VIS IMAGERY. WILL SEE A GRADUAL RISE TO VFR CIGS AROUND 3500 TO 4000 FEET THIS EVENING...WITH THE EXCEPTION OF BJI WHICH MAY REMAIN MVFR THROUGHOUT CURRENT TAF PD. && .FGF WATCHES/WARNINGS/ADVISORIES... ND...NONE. MN...NONE. && $$ SPEICHER nd AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WILMINGTON OH 620 AM EST WED NOV 19 2008 .SYNOPSIS... CLOUDS WILL SPILL BACK INTO THE REGION TODAY AS HIGH PRESSURE MOVES EAST INTO THE CAROLINAS. AN ALBERTA CLIPPER WILL DROP ACROSS THE GREAT LAKES TONIGHT...USHERING IN COLDER AIR AND THE CHANCE FOR SNOW SHOWERS THURSDAY INTO FRIDAY. MUCH BELOW NORMAL TEMPERATURES WILL PERSIST INTO THE WEEKEND. && .NEAR TERM /THROUGH TONIGHT/... SFC HI PRES RIDGE ALREADY SHIFTING TO EAST OF OH VLY THIS MRNG WITH LIGHT SRLY FLO DVLPG ACRS THE REGION. MID/HI LVL CLOUDS IN ADVANCE OF SFC LO OVER NRN MINNESOTA WILL CONTINUE TO OVERSPREAD THE FCST AREA THRU DAYBREAK. COLDEST MRNG SO FAR THIS FALL IN PROGRESS WITH TEMPS IN THE UPPER TEENS AND L20S. INCREASING CLOUDS SHOULD KEEP TEMPS FROM FALLING MUCH FURTHER FROM CURRENT (08Z) READINGS. INCREASING S/SW FLO ACRS THE OH VLY TODAY AS REGION BECOMES SITUATED BTWN DEPARTING SFC HI AND AFOREMENTIONED AND APPCHG SFC LO TO NORTHWEST. PRESENCE OF TIGHTENING SFC GRADIENT SHOULD ENSURE WIND GUSTS TO AROUND 20KTS THRU THE DAY. OF GREATER SCRUTINY WILL BE HOW CLOUD COVER SHAKES OUT ACRS REGION TODAY WITH LO LVL WAA DVLPG AHEAD OF SFC LO AND ASSOCD COLD FRONT. OF PARTICULAR INTEREST THIS MRNG IS AREA OF SC/AC ACRS ERN IOWA/NRN ILLINOIS IN REGION OF LO LVL CONV AND 285-290K ISENT LIFT. THIS AREA OF LOWER CIGS SHOULD SPREAD E/SE TO ENCOMPASS NRN 1/2 FCST AREA BY LATE MRNG HOURS. MODELS ALL HANDLE ISENT LIFT A BIT DIFFERENTLY... GFS/ECMWF ARE BOTH MORE EXPANSIVE AND DEEPER WITH ISENT LIFT BTWN 285-300K. RUC/NAM MEANWHILE INDCG LESS COVERAGE AND PUSHING GREATER CLOUD COVERAGE THRU FCST AREA MORE QUICKLY WITH POSSIBILITY AT INCREASING AMTS OF SUNSHINE DURING THE LATE AFTN. HAVE TAKEN A BLEND OF AVAIL MODEL DATA AND FOCUSED MSTLY CLDY SKIES ACRS NRN 1/2 FCST AREA FOR BETTER PART OF DAY WHERE DEEPEST MOISTURE SHOULD BE PRESENT. FURTHER SOUTH...HAVE INDICATED PTLY CLDY SKIES WITH AC DECK LKLY TO BE MAIN CIG LVL. SHOULD GFS SOLN BE REALIZED...ENTIRELY PLAUSIBLE THAT THIS PORTION OF THE FCST AREA WILL SEE A PERIOD WITH A GOOD DEAL OF CLOUDS DURING THE LATE MRNG/ERLY AFTN. DO EXPECT SOME DECREASE IN CLOUD COVERAGE PRIOR TO SUNSET THIS EVNG. MODEL CONSENSUS FAVORING SFC LO TRACK THRU CNTRL GRT LKS TO A POSN NEAR KERI IN NW PENNSYLVANIA BY 12Z THURS. ASSOCD COLD FRONT WILL PASS THRU FCST AREA THIS EVNG DRY WITH LACK OF ANY APPRECIABLE BNDRY LYR MOISTURE. SC DECK WILL EXPAND SOUTHEAST LATE TONIGHT IN WAKE OF FROPA AS INITIAL CAA SETS IN. GFS IN PARTICULAR TRYING TO SET UP LK MICHIGAN -SHSN DVLPMNT AS EARLY AS 06-12Z TIMEFRAME ACRS WEST CNTRL OH AS LO LVL WIND DIR VEERS TO 290-300 DEG. FEEL DVLPMNT OF FAVORABLE LO LVL FLO IS A TOUCH TOO FAST AND WITH 850 TEMPS AT -10 TO -8C BY THURS MRNG...BNDRY LYR LKLY TO NOT BE SUFFICIENT FOR -SHSN TO MAKE IT INTO NRN FCST AREA. HAVE INTRODUCED CHC FLURRIES LATE NORTH OF I-70. TEMPS...DESPITE S/SW WINDS AND WAA ACRS OH VLY TODAY...CLOUDS WILL BE THE DECIDING FACTOR WRT AFTN HIGHS. ONCE AGAIN APPEARS MODEL GUID STILL DOES NOT HAVE A GOOD HANDLE ON LO LVL THERMAL PROFILES AND CONSEQUENTLY IS TOO WARM WITH FCST HIGHS. HAVE UNDERCUT MOS BY 3-5 DEG ACRS THE BOARD...WITH TEMPS RANGING FROM THE U30S NORTH TO THE L40S SOUTH. CONSIDERING COLD START THIS MRNG IF CLOUDS ARE MORE EXPANSIVE AND HANG FOR MUCH OF THE DAY...FCST TEMPS WOULD NEED TO BE SHAVED EVEN FURTHER WITH MUCH OF THE FCST AREA STAYING BELOW 40 DEG. CLOSE TO MOS GUID FOR LOWS TONIGHT MAINLY IN THE U20S. && .SHORT TERM /THURSDAY THROUGH FRIDAY NIGHT/... COLDER AIR BECOMES FIRMLY ESTABLISHED ACRS REGION THURS AS UPR TROF RELOADS ACRS GRT LKS. LO LVL CAA WILL CYCLE THRU THE DAY THURS WITH PROGRESSIVELY COLDER AIR BEING DRIVEN SOUTHEAST INTO THE FCST AREA. ALL SIGNS POINT TO SCT -SHSN ACTIVITY BECOMING WELL DVLPD BY THE AFTN HOURS AS SVRL MID LVL S/WVS DROP THRU THE MEAN TROF ACRS THE LWR GRT LKS. MODEL SOUNDINGS LOOK AWFULLY FAMILIAR TO MON WITH INCREASING CAA PRODUCING STEEP LO LVL LAPSE RATES AND SHALLOW INSTABILITY. LO LVL WIND FIELDS SUPPORT LK MICHIGAN SNOW BANDS TO DROP SOUTHEAST INTO NRN 1/2 FCST AREA DURING THE AFTN HOURS. WILL CARRY SCT -SHSN FOR MOST LOCATIONS NORTH OF THE OHIO RIVER WITH FLURRIES AND/OR SCHC -SHSN OVER FAR SW FCST AREA. TRAILING SFC TROF AND STRONGER MID LVL S/WV WILL DROP ACRS REGION THURS NIGHT WHICH WILL KEEP -SHSN GOING THRU THE NIGHT. INTERESTING TO NOTE THAT AS NIGHT PROGRESSES...MODEL CONSENSUS INDCG A VEERING OF THE LO LVL WINDS THRU 850MB TO A MORE N/NW DIR. SHOULD THIS COME TO FRUITION...ENHANCED LK MICHIGAN BANDING WOULD FOCUS ACRS WESTERN FCST AREA AND THE CVG METRO IN PARTICULAR. WHILE THE DETAILS WILL COME INTO BETTER FOCUS OVER THE NEXT 24 HOURS...THIS SUGGESTS THAT SCT -SHSN WILL AFFECT ENTIRE FCST AREA ALL NIGHT. HAVE RAISED POPS EVERYWHERE AS A RESULT. SCT -SHSN/FLURRIES WILL PERSIST INTO FRI AS WELL AS UPR TROF IS SLOW TO SHIFT NORTH AND EAST AWAY FROM THE REGION. MODEL SOUNDINGS INDCG A SLOW BACKING OF LO LVL WIND FIELDS AS BROAD SFC HI TO WEST ATTEMPTS TO BUILD INTO OH VLY. THIS SHOULD SHIFT MUCH OF THE -SHSN ACTIVITY BACK TO THE NORTHEAST ACRS FCST AREA THRU THE DAY AND FOCUS GREATEST COVERAGE ACRS WEST CNTRL/CNTRL OH. WITH 850 TEMPS AT -14C...COMBINATION OF SHALLOW INSTABILITY AND STEEP LO LVL LAPSE RATES SHOULD ENHANCE COVERAGE IN THESE AREAS THRU MID AFTN. FURTHER SOUTH AND WEST ACRS FCST AREA...SHOULD SEE FLURRIES/ISOLD -SHSN GRADUALLY DIMINISH WITH INCREASING BREAKS IN CLOUDS DURING THE AFTN HOURS. ANY LK MICHIGAN INFLUENCE WILL BE CUT OFF BY LATE FRI AFTN AS LO LVL WINDS BACK TO WRLY. SFC HI PRES WILL THEN BUILD ACRS THE OH VLY FRI NIGHT WITH SKIES CLEARING. TEMPS...UNDERCUT MOS GUID THRU THE PERIOD. WITH CLOUDS AND SCT -SHSN THURS...EXPECT HIGHS MAINLY IN THE M30S. TEMPS WILL BE EVEN COLDER ON FRI WITH POSSIBILITY THAT NRN 1/2 FCST AREA DOES NOT GET ABV FREEZING LVL. AREAS NORTH OF I-70 POTENTIALLY MAY NOT EVEN GET OUT OF THE 20S. COLDEST NIGHT OF THE SEASON SO FAR LOOK POISED TO TAKE PLACE FRI NIGHT WITH ENTIRE FCST AREA LKLY TO DROP INTO THE TEENS. && .LONG TERM /SATURDAY THROUGH TUESDAY/... DRY WEATHER WILL CONTINUE SATURDAY THROUGH EARLY SUNDAY AS HIGH PRESSURE TRAVELS ACROSS THE SOUTHEAST CONUS. MODELS HAVING A DIFFICULT TIME WITH MID LEVEL S/WV MOVING ACRS REGION SATURDAY IN FAST NORTHWEST FLOW PATTERN. THIS FEATURE LIKELY TO ONLY BRING AN INCREASE IN MID/HIGH LEVEL CLOUDS FOR A BRIEF PERIOD SATURDAY. A POTENT CLIPPER IS PROGGED TO DROP INTO THE GREAT LAKES AND DRAG A COLD FRONT WITH ASSOCIATED MOISTURE THROUGH THE OHIO VALLEY SUNDAY NIGHT AND MONDAY. SNOW SHOWERS WILL LINGER ON TUESDAY BEHIND THE LOW. TEMPERATURES WILL REMAIN BELOW NORMAL THROUGH THE PERIOD. HIGHS WILL REMAIN IN THE 30S ON SATURDAY. 40S ARE EXPECTED AT ALL LOCATIONS ON SUNDAY...BEFORE ANOTHER SHOT OF COLDER AIR ARRIVES FOR MONDAY AND TUESDAY. && .AVIATION /11Z WEDNESDAY THROUGH SUNDAY/... SURFACE HIGH PRESSURE CENTERED OVER THE UPPER OHIO VALLEY REGION THIS MORNING WILL MOVE EAST OF THE REGION BY 18Z. WAA AHEAD OF AN APPROACHING CLIPPER SYSTEM WILL SPILL VARYING AMOUNTS OF LOW TO MID LVL MOISTURE ACRS THE REGION THROUGH 06Z. CIGS WILL REMAIN IN THE VFR CATEGORY THROUGH AT LEAST 05Z. THEREAFTER...AS THE COLD FRONT SWEEPS SOUTHEAST ACROSS THE REGION...MVFR CIGS WILL SPREAD ACROSS THE TAF SITES. WINDS WILL INCREASE FROM THE SOUTH ON THE BACK SIDE OF THE HIGH TODAY...BECOMING LOCALLY GUSTY TO AROUND 20 KNOTS DURING THE AFTN HOURS. WINDS WILL AGAIN BECOME LOCALLY GUSTY AROUND 20 KNOTS BEHIND COLD FRONTAL PASSAGE. OUTLOOK...MVFR CEILINGS EXPECTED THURSDAY THROUGH THURSDAY NIGHT. MVFR/IFR VSBYS POSSIBLE DUE TO SNOW SHOWERS THURSDAY NIGHT. && .ILN WATCHES/WARNINGS/ADVISORIES... OH...NONE. KY...NONE. IN...NONE. && $$ SYNOPSIS...RYAN NEAR TERM...RYAN SHORT TERM...RYAN LONG TERM...CONIGLIO/RYAN AVIATION...HICKMAN oh AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TULSA OK 911 PM CST THU NOV 20 2008 .UPDATE... && .DISCUSSION... ABOUT THE ONLY FORECAST QUESTION TO BE ANSWERED TONIGHT IS HOW LOW THE TEMPERATURES WILL GO. WITH A COLD AND VERY DRY AIRMASS ADVECTING INTO THE REGION... THE PREVIOUS FORECAST HAS UNDERCUT MAV GUIDANCE BY SEVERAL DEGREES AREAWIDE. CURRENTLY... TEMPERATURES HAVE BEEN SLOW TO FALL AS WINDS PERSIST ACROSS THE REGION. THE LATEST RUC AND NAM MODELS BOTH SHOW WINDS VERY SLOW TO DIE OUT. HOWEVER... ALL IT WILL TAKE IS A SHORT PERIOD OF CALM CONDITIONS BEFORE SUNRISE FOR TEMPERATURES TO CRATER. THEREFOR THE FORECAST IS EXTREMELY WIND-DEPENDENT TONIGHT. SHOULD WINDS REMAIN UP... TEMPERATURES WILL REMAIN ABOVE THE FORECAST MINIMUMS. THAT SAID... WILL HOLD FAST WITH PRIOR FORECAST... THEREFORE NO UPDATE IS PLANNED THIS EVENING. && .PRELIMINARY POINT TEMPS/POPS... TUL 23 46 31 55 / 0 0 0 0 FSM 24 48 25 54 / 0 0 0 0 MLC 23 48 29 56 / 0 0 0 0 BVO 18 46 23 53 / 0 0 0 0 FYV 18 43 23 50 / 0 0 0 0 BYV 18 42 21 50 / 0 0 0 0 MKO 22 47 26 51 / 0 0 0 0 MIO 19 45 27 52 / 0 0 0 0 F10 23 47 27 53 / 0 0 0 0 HHW 27 51 29 55 / 0 0 0 0 && .TSA WATCHES/WARNINGS/ADVISORIES... OK...FREEZE WARNING UNTIL 10 AM FRIDAY FOR OKZ049-OKZ053-OKZ054- OKZ055-OKZ056-OKZ057-OKZ058-OKZ059-OKZ060-OKZ061-OKZ062- OKZ063-OKZ064-OKZ065-OKZ066-OKZ067-OKZ068-OKZ069-OKZ070- OKZ071-OKZ072-OKZ073-OKZ074-OKZ075-OKZ076. AR...FREEZE WARNING UNTIL 10 AM FRIDAY FOR ARZ001-ARZ002-ARZ010- ARZ011-ARZ019-ARZ020-ARZ029. && $$ SHORT TERM...06 ok AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NORMAN OK 1116 PM CST TUE NOV 18 2008 .AVIATION...DRY WITH ONLY A FEW HIGH CLOUDS THROUGH THE PERIOD. WINDS ARE THE STORY...WITH MODERATE SOUTHWESTERLY LOW LEVEL JET TONIGHT THROUGH MIDDAY. JET MAKES SHARP ANGLE WITH TYPICALLY LIGHT SURFACE WINDS AT PNC...BUT SPEEDS - AND HEIGHT OF THE JET PER RUC AND 0430 UTC TAMDAR ASCENT SOUNDING FROM OKC - SUGGEST LLWS IS NOT NEEDED. WILL WATCH CLOSELY. OTHERWISE...LITTLE CHANGE FROM PREVIOUS TAFS EXCEPT TO BRING NORTH WINDS THROUGH A FEW MORE SITES WED EVENING. && BURKE && .PREV DISCUSSION... /ISSUED 958 PM CST TUE NOV 18 2008/ UPDATE... WINDS WILL REMAIN RATHER BRISK TONIGHT AHEAD OF TROUGH AND COLD FRONT. HAVE LOWERED TEMPS A FEW DEGREES SOUTHEAST WHERE LIGHTER WINDS DURING FIRST PART OF TONIGHT WILL ALLOW TEMPS TO COOL UNDER CLEAR SKIES. WINDS MAY ALSO DECREASE SLIGHTLY ACROSS NW OK BEFORE SUNRISE OTHERWISE TEMPS MAY NOT FALL TO FORECAST LOWS. WILL NOT MAKE CHANGES TO THE EXTENDED BUT MAY NEED TO LOWER HIGHS FOR FRIDAY AND SATURDAY IF NEW NAM IS CORRECT WITH STRENGTH AND POSITION OF COLD CANADIAN HIGH. && .PRELIMINARY POINT TEMPS/POPS... OKLAHOMA CITY OK 39 72 41 53 / 0 0 0 0 HOBART OK 39 72 38 52 / 0 0 0 0 WICHITA FALLS TX 40 79 43 54 / 0 0 0 0 GAGE OK 37 70 32 47 / 0 0 0 0 PONCA CITY OK 40 69 35 51 / 0 0 0 0 DURANT OK 38 72 44 61 / 0 0 0 0 && .OUN WATCHES/WARNINGS/ADVISORIES... OK...NONE. TX...NONE. && $$ 06/22/22 ok AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY NATIONAL WEATHER SERVICE RAPID CITY SD 908 AM MST WED NOV 19 2008 .UPDATE...SATELLITE IMAGERY SHOWS LOW STRATUS DECK CONTINUING TO PUSH S/SW ACROSS THE CWA FROM THE WHITE RIVER TO KPHP TO JUST NORTH AND EAST OF THE BLACK HILLS. LATEST RUC SHOWS THIS DECK MOVING INTO THE SOUTHERN BLACK HILLS AND STRETCHING INTO PARTS OF NORTHEAST WYOMING. WILL UPDATE THE FORECAST TO LOWER MAX TEMPS THIS AFTERNOON AND TWEAK THE STRATUS DECK TIMING. NO OTHER CHANGES NEEDED AT THIS TIME. && .PREVIOUS DISCUSSION [235 AM MST]...WATER VAPOR SHOWS SHORT WAVE ENERGY MOVING ALONG THE CNTRL U.S./CNDN BORDER. THIS IS PUSHING A COLD FRONT THRU THE NRN PLAINS...AND BASED ON SFC ANALYSIS IT IS ALREADY NEAR THE ND/SD BORDER. LOW CLOUDS SURGING SOUTH WITH THE COLD PUSH AND WILL PLAY HAVOC WITH HIGH TEMPS TODAY. TODAY...COLD FRONT WILL QUICKLY CROSS THE CWFA THIS MRNG WITH HIGH TEMPS BEING REALIZED RATHER EARLY...WITH TEMPS LIKELY FALLING TO NEAR OR JUST BELOW FREEZING BY LATE AFTN. NO PCPN IS CURRENTLY BEING OBSERVED WITH THE ASSOCD LOW CLOUDS SPREADING SWD ACRS ND SO BELIEVE A DRY FCST IS BEST. TONIGHT...A BAND OF OVERUNNING SNOW WILL LIKELY DEVELOP ACRS MT AND SLIDE SEWD INTO OUR FAR WRN ZONES AS RIGHT ENTRANCE REGION OF JET STREAK PASSES OVERHEAD. COULD SEE AN INCH OR SO OF ACCUMULATION FROM THE BLKHLS WWD...BUT EXPECT SNOW TO BE LIGHT AND TOO SHORT IN DURATION TO AMOUNT TO MUCH MORE THAN THAT. THURSDAY...PCPN SHOULD COME TO AN END IN THE MRNG WITH CLEARING SKIES FROM THE NORTH AS SFC RIDGE NUDGES INTO THE CNTRL DAKOTAS. HAVE LOWERED HIGHS EVEN MORE WITH MOST AREAS REMAINING AT OR BELOW FREEZING ALL DAY. FRIDAY...BOTH THE GFS/ECMWF SHOW A RATHER POTENT SHORT WAVE RACING EWD ACRS THE NRN PLAINS...WHICH WILL AID IN SOME TEMP RECOVERY ESPECIALLY ACRS THE WRN ZONES WITH SOME DOWNSLOPE FLOW DEVELOPING. EXPECT A BAND OF PCPN TO DEVELOP AND SPREAD EAST ACRS OUR CWFA AS WLY FLOW OVERRUNS THE COOLER AIR AT THE SFC. EXTENDED...MEDIUM RANGE SOLUTIONS ARE NOW AGREEING A BIT BETTER WITH QUICK MOVING SHORTWAVE RIDGE ON SATURDAY...FOLLOWED BY A STRONG UPPER TROF SLIDING ACROSS THE NORTHERN PLAINS FOR SUNDAY INTO MONDAY. UPPER LEVEL RIDGE BEGINS TO BUILD BACK INTO THE AREA FOR THE MIDDLE OF NEXT WEEK. BEST CHANCES FOR PRECIP WILL BE ACROSS FAR WESTERN SOUTH DAKOTA AND NORTHEAST WYOMING SATURDAY NIGHT INTO SUNDAY...AS A COLD FRONT MOVES THROUGH THE AREA. TEMPERATURES WILL REMAIN NEAR SEASONAL AVERAGES. && .AVIATION...VFR CONDITIONS WILL DROP TO MVFR ACROSS MOST LOCATIONS AS A CLOUD DECK CROSSES THE AREA THIS MORNING BEHIND A DEPARTING COLD FRONT. BREEZY NORTH WINDS ARE ALSO EXPECTED THROUGH THE DAY. MVFR CIGS WILL CONTINUE INTO THE EVENING HOURS. && .UNR WATCHES/WARNINGS/ADVISORIES... SD...NONE. WY...NONE. && $$ CALDERON sd AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE FORT WORTH TX 1139 AM CST THU NOV 20 2008 .AVIATION... /18Z TAFS/ COLD FRONT IS MOVING MUCH FASTER THAN ORIGINALLY EXPECTED...AND HAS ALREADY MOVED THRU METRO. WINDS WERE VIRTUALLY CALM AHEAD OF THE FRONT...BUT INCREASED QUICKLY OUT OF THE NORTH AFTER FROPA. SUSTAINED WIND SPEEDS HAVE BEEN RANGING BETWEEN 10 AND 20 MPH WITH GUSTS UP TO 28 MPH. KACT WINDS ARE ALSO ALREADY SHIFTING TO THE NORTHWEST...BUT HAVE NOT INCREASED YET. ANTICIPATE WINDS TO INCREASE EVEN MORE AROUND 19Z AT ALL TAF SITES...AND CONTINUE THRU THE EVENING HOURS. TRANSITIONED WINDS TO THE NORTHEAST AND DROPPED SPEEDS TO AROUND 10-20 KTS AROUND 3Z AT ALL TAF SITES AS HIGH PRESSURE MOVES INTO REGION. EXPECT THOSE VALUES TO HOLD THRU REMAINDER OF TAF PERIOD ALONG WITH VFR CONDITIONS. 77/TDUD && .UPDATE... AS WITH MANY FROPA DAYS...TEMPS AND WINDS HAVE A WAY OF STRAYING FROM HOURLY GRID VALUES. A SECOND UPDATE THIS MORNING PRIMARILY RAISES MIDDAY AND AFTERNOON TEMPS. AGREE WITH RUC VALUES WHICH SHOW SOME MODERATING OF THE COLD AIR WITH SUNSHINE AND LOW HUMIDITY...POSTFRONTAL TEMPS WILL LIKELY REBOUND A BIT BEFORE LOSING STEAM LATER THIS AFTERNOON. REGARDLESS...BLUSTERY WINDS WILL ASSURE A CHILLY AFTERNOON...PARTICULARLY ACROSS NORTHERN HALF OF CWA...WHERE WINDS WILL BE STRONGEST AND GRASS FIRE DANGER WILL BE HIGH. THIN PATCH OF CLOUDS AT THE BASE OF THE FRONTAL INVERSION WILL CONTINUE SKIRTING WESTERN ZONES...BUT DUE TO BRIEF NATURE... WILL NOT AFFECT SKY WORDING. FULL UPDATE OF ZFP AND ALL OTHER PRODUCTS GOING OUT NOW. 25 && .PREV DISCUSSION... /ISSUED 455 AM CST THU NOV 20 2008/ 257 AM WIND SHIFT LINE IS NEAR A ROSWELL-LUBBOCK-FORT SMITH LINE AT 08Z WITH THE TRUE COLD AIR JUST PUSHING SOUTH OUT OF KANSAS. THIS LAG WILL PROVIDE A CHANCE TO WARM UP SOME 3 TO 4 HOURS BEHIND THE WIND SHIFT BEFORE THE MAIN COLD AIR ARRIVES. NO PRECIPITATION IS EXPECTED AS MOISTURE IS SHALLOW AND DEEP LIFT IS ABSENT. WINDS WILL INCREASE OVER THE NORTHERN HALF TODAY WITH GUSTS OF 30 TO 35 MPH POSSIBLE. ADD THIS TO OUR DRY FUELS AND THE GRASS FIRE DANGER WILL BE HIGH DURING THE AFTERNOON. A GRASS FIRE DANGER STATEMENT WILL BE ISSUED FOR AREAS GENERALLY NORTH OF AN EASTLAND TO EMORY LINE. THIS AIRMASS IS COLD ENOUGH FOR ANOTHER FREEZE OVER THE NORTHWEST HALF FRIDAY MORNING. SEASONAL CONDITIONS WILL PREVAIL THROUGH THE WEEKEND UNDER MOSTLY CLOUDY SKIES. ISENTROPIC RETURN FLOW WILL EXIST SATURDAY THROUGH SUNDAY EVENING AND WE SHOULD SEE SOME LIGHT RAIN SPREADING ACROSS THE CWA DURING THE PERIOD...ESPECIALLY ON SUNDAY. AS THE NEXT COLD FRONT NEARS SUNDAY NIGHT...INSTABILITY AND CAPE WILL INCREASE AND THUNDERSTORMS WILL BE POSSIBLE OVER THE EAST HALF BEFORE DAYBREAK MONDAY AND SPREADING SOUTHEAST DURING THE DAY. CURRENTLY...SEVERE STORMS ARE NOT ANTICIPATED. FAIR AND SEASONAL TUESDAY AND WEDNESDAY. CURRENTLY MODEL SOLUTIONS ARE FAVORING A PROGRESSIVE UPPER LOW OFF OF CALIFORNIA EARLY NEXT WEEK AND A SOUTHERN ROCKIES LEE-SIDE SYSTEM THAT COULD RESULT IN PRECIPITATION AROUND THANKSGIVING DAY AND ANOTHER SHOT OF COLD AIR AFTERWARD. 75 && .PRELIMINARY POINT TEMPS/POPS... DALLAS-FT. WORTH, TX 59 35 52 37 58 / 0 0 0 5 5 WACO, TX 66 36 53 39 59 / 0 0 0 5 5 PARIS, TX 57 29 48 31 53 / 0 0 0 5 5 DENTON, TX 57 30 50 35 58 / 0 0 0 5 5 MCKINNEY, TX 58 30 51 33 56 / 0 0 0 5 5 DALLAS, TX 60 35 52 38 58 / 0 0 0 5 5 TERRELL, TX 63 34 52 38 55 / 0 0 0 5 5 CORSICANA, TX 68 33 52 37 56 / 0 0 0 5 5 TEMPLE, TX 70 37 53 40 57 / 0 0 0 5 5 && .FWD WATCHES/WARNINGS/ADVISORIES... NONE. && $$ 77/25 tx AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE LUBBOCK TX 1126 AM CST THU NOV 20 2008 .AVIATION... NORTHERLY WINDS OF AROUND 25 KTS WITH GUSTS TO 35 KTS WILL GRADUALLY DIMINISH DURING THE AFTERNOON HOURS...BECOMING ROUGHLY IN THE 15G25 KT RANGE BY 21-22Z. THE SKIES WILL CONTINUE TO CLEAR OUT ON THE CAPROCK HOWEVER ANOTHER BAND OF LOW STRATUS/MVFR CEILINGS ACROSS KANSAS AND THE OKLA PANHANDLE WILL WORK SOUTH INTO THE AREA LATER THIS AFTERNOON/EVENING. THIS CLOUD DECK SHOULD SLOWLY BREAK UP AS IT MOVES SOUTH SO THERE IS UNCERTAINTY REGARDING EXTENT OF CLOUD COVER. WILL KEEP SKY SCATTERED IN TAFS FOR NOW BUT POSSIBILITY REMAINS FOR PERIOD OF MVFR CEILINGS AT/NEAR EITHER TERMINAL FOR A PERIOD FROM ABOUT 21Z TO 03Z. THE WIND WILL BECOME LIGHT AND VARIABLE EARLY FRIDAY MORNING AND BEGIN TO COME AROUND TO THE SOUTH-SOUTHWEST DURING THE DAY FRIDAY. && .PREV DISCUSSION... /ISSUED 557 AM CST THU NOV 20 2008/ AVIATION... COLD FRONT SOUTH OF KLBB AND KCDS...WITH MVFR CEILINGS SPREADING SOUTH TOWARDS KLBB. TIMING CLOUDS USING SATELLITE BRINGS OVERCAST 1400 FEET AGL DECK TO KLBB JUST AFTER 13Z...SIMILAR TO LATEST RUC MODEL RUN. LOW CLOUDS NEAR KCDS MAY BRIEFLY CIG AROUND 1500-2000 FEET AGL NEAR 13Z...BUT ARE MUCH MORE SHREDDED. LOW CLOUDS SHOULD ERODE AT KLBB BY ABOUT 17Z USING MODEL INTERPOLATION...BUT TIMING IS UNCERTAIN PLUS OR MINUS AN HOUR OR SO. WINDS ALREADY INCREASING TO OVER 20 KTS AND WITH TIGHT INITIAL PRESSURE GRADIENT COULD REACH SUSTAINED 23-25KTS GUSTS 32-34 KTS AT BOTH TERMINALS THROUGH MID MORNING. WIND GUSTS SHOULD SLOWLY TAPER AFTER THAT. MCQUEEN PREV DISCUSSION... /ISSUED 356 AM CST THU NOV 20 2008/ SHORT TERM... SURFACE COLD FRONT NOW SURGING INTO SOUTHERN SOUTH PLAINS AND SOUTHERN ROLLING PLAINS...AND WILL CLEAR ENTIRE AREA BY DAYBREAK. A LOW CLOUD DECK IS FILLING IN BEHIND THE FRONT OVER THE NORTHERN PANHANDLE...THOUGH A BIT MORE BROKEN OVER THE NORTHEASTERN PANHANDLE. THE RUC13 AND NAM12 SEEM WELL INITIALIZED AND ARE SIMILAR DEPICTING A CLOUD LAYER AT THE H850MB LAYER DEVELOPING SOUTHWARD MAINLY ON THE CAPROCK THIS MORNING. SATURATION LAYER OVER THE ROLLING PLAINS APPEARS LESS PRONOUNCED. MOST OF THESE LOW CLOUDS ARE EXPECTED TO BURN OFF BY LATE MORNING...BUT WRF/NAM SUGGESTS LAYER MAY PERSIST A BIT LONGER WESTERN OR NORTHWESTERN ZONES. NEWEST GUIDANCE TEMPERATURES TODAY WERE A NOTCH COOLER ANYWAY...AND CHOSE TO LOWER ANOTHER NOTCH OVER NORTHWESTERN ZONES GIVEN LOW CLOUD OPPORTUNITY. WINDS WILL INCREASE QUICKLY AFTER DAYBREAK INTO WINDY CATEGORY...BUT ALL GUIDANCE MAINTAINS SPEEDS JUST SHORT OF WIND ADVISORY CRITERIA. WINDS WILL GRADUALLY TAPER OFF DURING THE AFTERNOON WITH A WEAKER PRESSURE GRADIENT. SURFACE RIDGE WILL NOSE FURTHER SOUTH INTO SOUTHERN PLAINS TONIGHT WITH A FLAT PRESSURE GRADIENT DOMINATING THE AREA MOST OF THE NIGHT. THIS SHOULD ASSIST IN DE-COUPLING THE LOWER ATMOSPHERIC TEMPERATURE PROFILE AND ALLOW A CHILLY NIGHT TO OCCUR OVER THE ENTIRE AREA. LOW CLOUDS MAY THREATEN REFORMING NEAR WESTERN OR NORTHWESTERN ZONES AGAIN EARLY...BUT SHOULD TREND TOWARDS MORE ISENTROPIC LOWER ATMOSPHERIC DOWNGLIDE AS THE NIGHT GOES ON. A BIT OF MOSTLY THIN HIGH CLOUDS PASSING OVERHEAD SHOULD NOT SIGNIFICANTLY ALTER SURFACE TEMPERATURE EXPECTATIONS. MCQUEEN LONG TERM... THE SURFACE RIDGE AXIS ACROSS THE AREA EARLY FRIDAY WILL QUICKLY BE REPLACED BY A SURFACE TROUGH DURG THE DAY...AS A SFC LOW DEEPENS OVER EASTERN COLORADO IN RESPONSE TO A FAST MOVG H50 SHORTWAVE SKIRTING EAST FM THE NORTHERN ROCKIES INTO THE PLAINS. AS THE SFC PRESSURE GRADIENT TIGHTENS...SOUTH WINDS WILL INCREASE TO 15 TO 20 MPH ON FRI AFTN ESPECIALLY ON THE CAPROCK. THIS WILL FAVOR AREAS ACROSS THE WESTERN CWFA TO WARM SEVERAL DEGS FM THURSDAY...WITH THE REMAINDER OF THE CWFA ONLY EXPERIENCING A SLIGHT RISE. FOR THE WEEKEND...NEAR ZONAL UPPER FLOW WILL SUSTAIN A SFC LEE TROUGH ACRS THE REGION PROMOTING ABOVE NORMAL TEMPS. WARMEST READINGS WILL BE REALIZED SUNDAY AS A H85 THERMAL RIDGE STRENGTHENS OVER WEST TEXAS AHEAD OF THE NEXT UPPER TROUGH/COLD FRONT DROPPING SOUTH FROM THE CENTRAL PLAINS. THIS FRONT IS ON SCHEDULE TO ARRIVE SUNDAY NIGHT WITH TEMPS RETURNING TO NORMAL FOR MONDAY. A WARMING TREND WILL THEN ENSUE TUES AND WED AS AN UPPER RIDGE TRANSLATES THROUGH THE SRN PLAINS. STILL APPEARS THAT THANKSGIVING DAY WILL BE NICE AND MILD...BUT WILL BE WATCHING FOR THE POSSIBLY OF A STRONG STORM SYSTEM DEVELOPING OVER SOUTHERN CALIFORNIA... WHICH COULD BRING SOME WEATHER CHANGES FOR THE REMAINDER OF THE HOLIDAY WEEKEND. && .PRELIMINARY POINT TEMPS/POPS... FRIONA 41 19 53 27 63 / 0 0 0 0 0 TULIA 44 21 50 27 61 / 0 0 0 0 0 PLAINVIEW 46 22 50 27 62 / 0 0 0 0 0 LEVELLAND 49 20 52 26 64 / 0 0 0 0 0 LUBBOCK 49 23 51 29 63 / 0 0 0 0 0 DENVER CITY 49 22 53 27 63 / 0 0 0 0 0 BROWNFIELD 50 21 52 27 64 / 0 0 0 0 0 CHILDRESS 49 26 50 28 62 / 0 0 0 0 0 SPUR 50 22 51 29 63 / 0 0 0 0 0 ASPERMONT 52 22 52 30 64 / 0 0 0 0 0 && .LUB WATCHES/WARNINGS/ADVISORIES... NONE. && $$ 33/99/99 tx AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE FORT WORTH TX 1106 AM CST THU NOV 20 2008 .UPDATE... AS WITH MANY FROPA DAYS...TEMPS AND WINDS HAVE A WAY OF STRAYING FROM HOURLY GRID VALUES. A SECOND UPDATE THIS MORNING PRIMARILY RAISES MIDDAY AND AFTERNOON TEMPS. AGREE WITH RUC VALUES WHICH SHOW SOME MODERATING OF THE COLD AIR WITH SUNSHINE AND LOW HUMIDITY...POSTFRONTAL TEMPS WILL LIKELY REBOUND A BIT BEFORE LOSING STEAM LATER THIS AFTERNOON. REGARDLESS...BLUSTERY WINDS WILL ASSURE A CHILLY AFTERNOON...PARTICULARLY ACROSS NORTHERN HALF OF CWA...WHERE WINDS WILL BE STRONGEST AND GRASS FIRE DANGER WILL BE HIGH. THIN PATCH OF CLOUDS AT THE BASE OF THE FRONTAL INVERSION WILL CONTINUE SKIRTING WESTERN ZONES...BUT DUE TO BRIEF NATURE... WILL NOT AFFECT SKY WORDING. FULL UPDATE OF ZFP AND ALL OTHER PRODUCTS GOING OUT NOW. 25 && .AVIATION... THE COLD FRONT WAS LOCATED NEAR A CARLSBAD...WICHITA FALLS...TO MCALESTER LINE AT 430 AM. THE STRONGER WINDS LAGGED THE WIND SHIFT LINE BY ABOUT 30 MILES. LINEAR EXTRAPOLATION BRINGS THE COLD FRONT TO THE METROPLEX TAF SITES BETWEEN 15 AND 16Z AND WACO A COUPLE HOURS LATER. A LIGHT SOUTH/SOUTHWEST WIND EARLY WILL TURN TO THE NORTH AND INCREASE WITH THE FRONT. THE STRONGEST WINDS SHOULD LAG THE WIND SHIFT BY AN HOUR OR TWO. WILL CARRY A PREVAILING NORTH WIND AROUND 18 KNOTS WITH SOME GUSTS NEAR 30 KNOTS BEHIND THE FRONT. WIND SPEEDS WILL DECREASE AFTER SUNSET BUT REMAIN NORTH BETWEEN 12 AND 14 KNOTS THROUGH EARLY FRIDAY MORNING. OTHERWISE VFR WITH ONLY SOME POST FRONTAL FEW/SCATTERED CU. .79... && .PREV DISCUSSION... /ISSUED 455 AM CST THU NOV 20 2008/ 257 AM WIND SHIFT LINE IS NEAR A ROSWELL-LUBBOCK-FORT SMITH LINE AT 08Z WITH THE TRUE COLD AIR JUST PUSHING SOUTH OUT OF KANSAS. THIS LAG WILL PROVIDE A CHANCE TO WARM UP SOME 3 TO 4 HOURS BEHIND THE WIND SHIFT BEFORE THE MAIN COLD AIR ARRIVES. NO PRECIPITATION IS EXPECTED AS MOISTURE IS SHALLOW AND DEEP LIFT IS ABSENT. WINDS WILL INCREASE OVER THE NORTHERN HALF TODAY WITH GUSTS OF 30 TO 35 MPH POSSIBLE. ADD THIS TO OUR DRY FUELS AND THE GRASS FIRE DANGER WILL BE HIGH DURING THE AFTERNOON. A GRASS FIRE DANGER STATEMENT WILL BE ISSUED FOR AREAS GENERALLY NORTH OF AN EASTLAND TO EMORY LINE. THIS AIRMASS IS COLD ENOUGH FOR ANOTHER FREEZE OVER THE NORTHWEST HALF FRIDAY MORNING. SEASONAL CONDITIONS WILL PREVAIL THROUGH THE WEEKEND UNDER MOSTLY CLOUDY SKIES. ISENTROPIC RETURN FLOW WILL EXIST SATURDAY THROUGH SUNDAY EVENING AND WE SHOULD SEE SOME LIGHT RAIN SPREADING ACROSS THE CWA DURING THE PERIOD...ESPECIALLY ON SUNDAY. AS THE NEXT COLD FRONT NEARS SUNDAY NIGHT...INSTABILITY AND CAPE WILL INCREASE AND THUNDERSTORMS WILL BE POSSIBLE OVER THE EAST HALF BEFORE DAYBREAK MONDAY AND SPREADING SOUTHEAST DURING THE DAY. CURRENTLY...SEVERE STORMS ARE NOT ANTICIPATED. FAIR AND SEASONAL TUESDAY AND WEDNESDAY. CURRENTLY MODEL SOLUTIONS ARE FAVORING A PROGRESSIVE UPPER LOW OFF OF CALIFORNIA EARLY NEXT WEEK AND A SOUTHERN ROCKIES LEE-SIDE SYSTEM THAT COULD RESULT IN PRECIPITATION AROUND THANKSGIVING DAY AND ANOTHER SHOT OF COLD AIR AFTERWARD. 75 && .PRELIMINARY POINT TEMPS/POPS... DALLAS-FT. WORTH, TX 59 35 52 37 58 / 0 0 0 5 5 WACO, TX 66 36 53 39 59 / 0 0 0 5 5 PARIS, TX 57 29 48 31 53 / 0 0 0 5 5 DENTON, TX 57 30 50 35 58 / 0 0 0 5 5 MCKINNEY, TX 58 30 51 33 56 / 0 0 0 5 5 DALLAS, TX 60 35 52 38 58 / 0 0 0 5 5 TERRELL, TX 63 34 52 38 55 / 0 0 0 5 5 CORSICANA, TX 68 33 52 37 56 / 0 0 0 5 5 TEMPLE, TX 70 37 53 40 57 / 0 0 0 5 5 && .FWD WATCHES/WARNINGS/ADVISORIES... NONE. && $$ 77/25 tx AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE MIDLAND/ODESSA TX 842 AM CST THU NOV 20 2008 .UPDATE... UPDATED MAXIMUM TEMPERATURES AND WINDS. && .DISCUSSION... A STRONG COLD FRONT WILL MAKE ITS WAY THROUGH WEST TEXAS AND SOUTHEASTERN NEW MEXICO TODAY. STRONGER WINDS WILL ACCOMPANY THE PASSAGE OF THE COLD FRONT. IN THE PLAINS AREAS THE WIND SHOULD REMAIN JUST BELOW ADVISORY CRITERIA. WIND SPEEDS THROUGH THE GAP AREAS OF THE GUADALUPE MOUNTAINOUS SHOULD REMAIN JUST BELOW WARNING CRITERIA. COLDER THAN NORMAL TEMPERATURES ARE EXPECTED AFTER THE PASSAGE OF THE FRONT. && .PREV DISCUSSION... /ISSUED 605 AM CST THU NOV 20 2008/ DISCUSSION... SEE AVIATION DISCUSSION BELOW. AVIATION... THE LATEST SURFACE OBSERVATIONS SHOW THE COLD FRONT ACROSS THE SOUTH PLAINS ALONG A DENVER CITY LINE TO JAYTON LINE. THE COLD FRONT WILL CONTINUE TO PUSH SOUTH TODAY...WITH THE LATEST RUC13 MODEL HAVING A GOOD HANDLE ON THE POSITION OF THE FRONT. OVERALL...THE INHERITED SET OF TAFS HANDLES THE SITUATION WELL. WE STILL EXPECT A DECK OF STRATOCU TO MOVE SOUTH/DEVELOP THIS MORNING...WITH ALL BUT KFST EXPECTED TO SEE A TEMPORARY ROUND OF MVFR CIGS THIS MORNING. AVAILABLE MODEL DATA SUGGESTS THE MOISTURE MAY MIX/DECREASE AS IT MOVES SOUTH INTO THE TRANS PECOS REGION...INCLUDING KFST. FOR NOW...WILL CONTINUE A SCT DECK AT KFST...BUT HAVE OPTED TO REMOVE THE BKN LAYER. WE HAVE ALSO INCREASED WINDS SLIGHTLY AT AREA TERMINALS BASED ON THE LATEST RUC13 DATA. WINDS WILL DECREASE LATE THIS AFTERNOON AND EVENING FROM NORTH TO SOUTH AND WILL REMOVE MENTION OF GUSTS AT ALL SITES IN THE 23Z-02Z TIME FRAME AS THE SURFACE BASED INVERSION DEVELOPS. PREV DISCUSSION... /ISSUED 348 AM CST THU NOV 20 2008/ DISCUSSION... A STRONG POLAR COLD FRONT WILL ENTER THE PERMIAN BASIN AROUND SUNRISE THIS MORNING AND CONTINUE RAPIDLY SOUTHWARD TO SOUTH OF THE BIG BEND BY SUNSET. WINDY AND MARKEDLY COOLER CONDITIONS EXPECTED WITH THIS FRONTAL PASSAGE TODAY...WITH TEMPERATURES STEADILY DROPPING INTO THE 20S MOST AREAS OVERNIGHT DESPITE SOME LINGERING LOW CLOUD COVER. NORTHEAST WINDS WILL INCREASE IN THE MOUNTAIN PASSES LATE TODAY INTO TONIGHT BEHIND THIS COLD FRONT...HOWEVER WIND SPEEDS SHOULD REMAIN JUST BELOW HIGH WIND CRITERIA. COOL AND DRY NORTHWEST FLOW ALOFT AND A STRONG EXPANSIVE AREA OF SURFACE HIGH PRESSURE WILL AID IN KEEPING THE COLD AIR MASS IN PLACE FRIDAY WITH AFTERNOON HIGHS STRUGGLING TO REACH THE 50S AND FRIDAY NIGHT LOWS ACROSS THE PERMIAN BASIN NEAR THE FREEZING MARK. TEMPERATURES WILL GRADUALLY WARM/MODERATE BACK TO SEASONAL NORMS OVER THE WEEKEND AS SURFACE HIGH PRESSURE SLIDES TO OUR EAST AND LEE-SIDE SURFACE TROUGHING REDEVELOPS ON SUNDAY. THE NEXT VIGOROUS NORTHERN STREAM UPPER TROUGH WILL DIVE DOWN FROM THE NORTHERN PLAINS INTO THE GREAT LAKES AREA ON SUNDAY... DRIVING ANOTHER DRY SURFACE COLD FRONT SOUTHWARD INTO THE PERMIAN BASIN SUNDAY NIGHT. TEMPERATURES ARE NOT EXPECTED TO BE QUITE AS COOL NOR CONDITIONS NOT AS WINDY WITH THIS FRONTAL PASSAGE AS THE MAIN COLD SURGE WILL BE ACROSS THE MISSISSIPPI VALLEY WELL TO OUR EAST. && .PRELIMINARY POINT TEMPS/POPS... BIG SPRING TX 50 26 51 34 / 0 0 0 0 CARLSBAD NM 52 26 54 31 / 0 0 0 0 DRYDEN TX 63 33 52 37 / 0 0 0 10 FORT STOCKTON TX 56 28 55 39 / 0 0 0 0 GUADALUPE PASS TX 53 24 47 36 / 0 0 0 0 HOBBS NM 52 24 50 30 / 0 0 0 0 MARFA TX 59 25 54 26 / 0 0 0 0 MIDLAND INTL AIRPORT TX 50 25 49 32 / 0 0 0 0 ODESSA TX 50 26 48 35 / 0 0 0 0 WINK TX 55 28 53 32 / 0 0 0 0 && .MAF WATCHES/WARNINGS/ADVISORIES... NM...NONE. TX...NONE. && $$ 76/99 tx AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE MIDLAND/ODESSA TX 605 AM CST THU NOV 20 2008 .DISCUSSION... SEE AVIATION DISCUSSION BELOW. && .AVIATION... THE LATEST SURFACE OBSERVATIONS SHOW THE COLD FRONT ACROSS THE SOUTH PLAINS ALONG A DENVER CITY LINE TO JAYTON LINE. THE COLD FRONT WILL CONTINUE TO PUSH SOUTH TODAY...WITH THE LATEST RUC13 MODEL HAVING A GOOD HANDLE ON THE POSITION OF THE FRONT. OVERALL...THE INHERITED SET OF TAFS HANDLES THE SITUATION WELL. WE STILL EXPECT A DECK OF STRATOCU TO MOVE SOUTH/DEVELOP THIS MORNING...WITH ALL BUT KFST EXPECTED TO SEE A TEMPORARY ROUND OF MVFR CIGS THIS MORNING. AVAILABLE MODEL DATA SUGGESTS THE MOISTURE MAY MIX/DECREASE AS IT MOVES SOUTH INTO THE TRANS PECOS REGION...INCLUDING KFST. FOR NOW...WILL CONTINUE A SCT DECK AT KFST...BUT HAVE OPTED TO REMOVE THE BKN LAYER. WE HAVE ALSO INCREASED WINDS SLIGHTLY AT AREA TERMINALS BASED ON THE LATEST RUC13 DATA. WINDS WILL DECREASE LATE THIS AFTERNOON AND EVENING FROM NORTH TO SOUTH AND WILL REMOVE MENTION OF GUSTS AT ALL SITES IN THE 23Z-02Z TIME FRAME AS THE SURFACE BASED INVERSION DEVELOPS. && .PREV DISCUSSION... /ISSUED 348 AM CST THU NOV 20 2008/ DISCUSSION... A STRONG POLAR COLD FRONT WILL ENTER THE PERMIAN BASIN AROUND SUNRISE THIS MORNING AND CONTINUE RAPIDLY SOUTHWARD TO SOUTH OF THE BIG BEND BY SUNSET. WINDY AND MARKEDLY COOLER CONDITIONS EXPECTED WITH THIS FRONTAL PASSAGE TODAY...WITH TEMPERATURES STEADILY DROPPING INTO THE 20S MOST AREAS OVERNIGHT DESPITE SOME LINGERING LOW CLOUD COVER. NORTHEAST WINDS WILL INCREASE IN THE MOUNTAIN PASSES LATE TODAY INTO TONIGHT BEHIND THIS COLD FRONT...HOWEVER WIND SPEEDS SHOULD REMAIN JUST BELOW HIGH WIND CRITERIA. COOL AND DRY NORTHWEST FLOW ALOFT AND A STRONG EXPANSIVE AREA OF SURFACE HIGH PRESSURE WILL AID IN KEEPING THE COLD AIR MASS IN PLACE FRIDAY WITH AFTERNOON HIGHS STRUGGLING TO REACH THE 50S AND FRIDAY NIGHT LOWS ACROSS THE PERMIAN BASIN NEAR THE FREEZING MARK. TEMPERATURES WILL GRADUALLY WARM/MODERATE BACK TO SEASONAL NORMS OVER THE WEEKEND AS SURFACE HIGH PRESSURE SLIDES TO OUR EAST AND LEE-SIDE SURFACE TROUGHING REDEVELOPS ON SUNDAY. THE NEXT VIGOROUS NORTHERN STREAM UPPER TROUGH WILL DIVE DOWN FROM THE NORTHERN PLAINS INTO THE GREAT LAKES AREA ON SUNDAY... DRIVING ANOTHER DRY SURFACE COLD FRONT SOUTHWARD INTO THE PERMIAN BASIN SUNDAY NIGHT. TEMPERATURES ARE NOT EXPECTED TO BE QUITE AS COOL NOR CONDITIONS NOT AS WINDY WITH THIS FRONTAL PASSAGE AS THE MAIN COLD SURGE WILL BE ACROSS THE MISSISSIPPI VALLEY WELL TO OUR EAST. && .MAF WATCHES/WARNINGS/ADVISORIES... NM...NONE. TX...NONE. && $$ 06 tx AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LUBBOCK TX 557 AM CST THU NOV 20 2008 .AVIATION... COLD FRONT SOUTH OF KLBB AND KCDS...WITH MVFR CEILINGS SPREADING SOUTH TOWARDS KLBB. TIMING CLOUDS USING SATELLITE BRINGS OVERCAST 1400 FEET AGL DECK TO KLBB JUST AFTER 13Z...SIMILAR TO LATEST RUC MODEL RUN. LOW CLOUDS NEAR KCDS MAY BRIEFLY CIG AROUND 1500-2000 FEET AGL NEAR 13Z...BUT ARE MUCH MORE SHREDDED. LOW CLOUDS SHOULD ERODE AT KLBB BY ABOUT 17Z USING MODEL INTERPOLATION...BUT TIMING IS UNCERTAIN PLUS OR MINUS AN HOUR OR SO. WINDS ALREADY INCREASING TO OVER 20 KTS AND WITH TIGHT INITIAL PRESSURE GRADIENT COULD REACH SUSTAINED 23-25KTS GUSTS 32-34 KTS AT BOTH TERMINALS THROUGH MID MORNING. WIND GUSTS SHOULD SLOWLY TAPER AFTER THAT. MCQUEEN && .PREV DISCUSSION... /ISSUED 356 AM CST THU NOV 20 2008/ SHORT TERM... SURFACE COLD FRONT NOW SURGING INTO SOUTHERN SOUTH PLAINS AND SOUTHERN ROLLING PLAINS...AND WILL CLEAR ENTIRE AREA BY DAYBREAK. A LOW CLOUD DECK IS FILLING IN BEHIND THE FRONT OVER THE NORTHERN PANHANDLE...THOUGH A BIT MORE BROKEN OVER THE NORTHEASTERN PANHANDLE. THE RUC13 AND NAM12 SEEM WELL INITIALIZED AND ARE SIMILAR DEPICTING A CLOUD LAYER AT THE H850MB LAYER DEVELOPING SOUTHWARD MAINLY ON THE CAPROCK THIS MORNING. SATURATION LAYER OVER THE ROLLING PLAINS APPEARS LESS PRONOUNCED. MOST OF THESE LOW CLOUDS ARE EXPECTED TO BURN OFF BY LATE MORNING...BUT WRF/NAM SUGGESTS LAYER MAY PERSIST A BIT LONGER WESTERN OR NORTHWESTERN ZONES. NEWEST GUIDANCE TEMPERATURES TODAY WERE A NOTCH COOLER ANYWAY...AND CHOSE TO LOWER ANOTHER NOTCH OVER NORTHWESTERN ZONES GIVEN LOW CLOUD OPPORTUNITY. WINDS WILL INCREASE QUICKLY AFTER DAYBREAK INTO WINDY CATEGORY...BUT ALL GUIDANCE MAINTAINS SPEEDS JUST SHORT OF WIND ADVISORY CRITERIA. WINDS WILL GRADUALLY TAPER OFF DURING THE AFTERNOON WITH A WEAKER PRESSURE GRADIENT. SURFACE RIDGE WILL NOSE FURTHER SOUTH INTO SOUTHERN PLAINS TONIGHT WITH A FLAT PRESSURE GRADIENT DOMINATING THE AREA MOST OF THE NIGHT. THIS SHOULD ASSIST IN DE-COUPLING THE LOWER ATMOSPHERIC TEMPERATURE PROFILE AND ALLOW A CHILLY NIGHT TO OCCUR OVER THE ENTIRE AREA. LOW CLOUDS MAY THREATEN REFORMING NEAR WESTERN OR NORTHWESTERN ZONES AGAIN EARLY...BUT SHOULD TREND TOWARDS MORE ISENTROPIC LOWER ATMOSPHERIC DOWNGLIDE AS THE NIGHT GOES ON. A BIT OF MOSTLY THIN HIGH CLOUDS PASSING OVERHEAD SHOULD NOT SIGNIFICANTLY ALTER SURFACE TEMPERATURE EXPECTATIONS. MCQUEEN LONG TERM... THE SURFACE RIDGE AXIS ACROSS THE AREA EARLY FRIDAY WILL QUICKLY BE REPLACED BY A SURFACE TROUGH DURG THE DAY...AS A SFC LOW DEEPENS OVER EASTERN COLORADO IN RESPONSE TO A FAST MOVG H50 SHORTWAVE SKIRTING EAST FM THE NORTHERN ROCKIES INTO THE PLAINS. AS THE SFC PRESSURE GRADIENT TIGHTENS...SOUTH WINDS WILL INCREASE TO 15 TO 20 MPH ON FRI AFTN ESPECIALLY ON THE CAPROCK. THIS WILL FAVOR AREAS ACROSS THE WESTERN CWFA TO WARM SEVERAL DEGS FM THURSDAY...WITH THE REMAINDER OF THE CWFA ONLY EXPERIENCING A SLIGHT RISE. FOR THE WEEKEND...NEAR ZONAL UPPER FLOW WILL SUSTAIN A SFC LEE TROUGH ACRS THE REGION PROMOTING ABOVE NORMAL TEMPS. WARMEST READINGS WILL BE REALIZED SUNDAY AS A H85 THERMAL RIDGE STRENGTHENS OVER WEST TEXAS AHEAD OF THE NEXT UPPER TROUGH/COLD FRONT DROPPING SOUTH FROM THE CENTRAL PLAINS. THIS FRONT IS ON SCHEDULE TO ARRIVE SUNDAY NIGHT WITH TEMPS RETURNING TO NORMAL FOR MONDAY. A WARMING TREND WILL THEN ENSUE TUES AND WED AS AN UPPER RIDGE TRANSLATES THROUGH THE SRN PLAINS. STILL APPEARS THAT THANKSGIVING DAY WILL BE NICE AND MILD...BUT WILL BE WATCHING FOR THE POSSIBLY OF A STRONG STORM SYSTEM DEVELOPING OVER SOUTHERN CALIFORNIA... WHICH COULD BRING SOME WEATHER CHANGES FOR THE REMAINDER OF THE HOLIDAY WEEKEND. && .PRELIMINARY POINT TEMPS/POPS... FRIONA 41 19 53 27 63 / 0 0 0 0 0 TULIA 44 21 50 27 61 / 0 0 0 0 0 PLAINVIEW 46 22 50 27 62 / 0 0 0 0 0 LEVELLAND 49 20 52 26 64 / 0 0 0 0 0 LUBBOCK 49 23 51 29 63 / 0 0 0 0 0 DENVER CITY 49 22 53 27 63 / 0 0 0 0 0 BROWNFIELD 50 21 52 27 64 / 0 0 0 0 0 CHILDRESS 49 26 50 28 62 / 0 0 0 0 0 SPUR 50 22 51 29 63 / 0 0 0 0 0 ASPERMONT 52 22 52 30 64 / 0 0 0 0 0 && .LUB WATCHES/WARNINGS/ADVISORIES... NONE. && $$ 05/21/05 tx AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LUBBOCK TX 356 AM CST THU NOV 20 2008 .SHORT TERM... SURFACE COLD FRONT NOW SURGING INTO SOUTHERN SOUTH PLAINS AND SOUTHERN ROLLING PLAINS...AND WILL CLEAR ENTIRE AREA BY DAYBREAK. A LOW CLOUD DECK IS FILLING IN BEHIND THE FRONT OVER THE NORTHERN PANHANDLE...THOUGH A BIT MORE BROKEN OVER THE NORTHEASTERN PANHANDLE. THE RUC13 AND NAM12 SEEM WELL INITIALIZED AND ARE SIMILAR DEPICTING A CLOUD LAYER AT THE H850MB LAYER DEVELOPING SOUTHWARD MAINLY ON THE CAPROCK THIS MORNING. SATURATION LAYER OVER THE ROLLING PLAINS APPEARS LESS PRONOUNCED. MOST OF THESE LOW CLOUDS ARE EXPECTED TO BURN OFF BY LATE MORNING...BUT WRF/NAM SUGGESTS LAYER MAY PERSIST A BIT LONGER WESTERN OR NORTHWESTERN ZONES. NEWEST GUIDANCE TEMPERATURES TODAY WERE A NOTCH COOLER ANYWAY...AND CHOSE TO LOWER ANOTHER NOTCH OVER NORTHWESTERN ZONES GIVEN LOW CLOUD OPPORTUNITY. WINDS WILL INCREASE QUICKLY AFTER DAYBREAK INTO WINDY CATEGORY...BUT ALL GUIDANCE MAINTAINS SPEEDS JUST SHORT OF WIND ADVISORY CRITERIA. WINDS WILL GRADUALLY TAPER OFF DURING THE AFTERNOON WITH A WEAKER PRESSURE GRADIENT. SURFACE RIDGE WILL NOSE FURTHER SOUTH INTO SOUTHERN PLAINS TONIGHT WITH A FLAT PRESSURE GRADIENT DOMINATING THE AREA MOST OF THE NIGHT. THIS SHOULD ASSIST IN DE-COUPLING THE LOWER ATMOSPHERIC TEMPERATURE PROFILE AND ALLOW A CHILLY NIGHT TO OCCUR OVER THE ENTIRE AREA. LOW CLOUDS MAY THREATEN REFORMING NEAR WESTERN OR NORTHWESTERN ZONES AGAIN EARLY...BUT SHOULD TREND TOWARDS MORE ISENTROPIC LOWER ATMOSPHERIC DOWNGLIDE AS THE NIGHT GOES ON. A BIT OF MOSTLY THIN HIGH CLOUDS PASSING OVERHEAD SHOULD NOT SIGNIFICANTLY ALTER SURFACE TEMPERATURE EXPECTATIONS. MCQUEEN && .LONG TERM... THE SURFACE RIDGE AXIS ACROSS THE AREA EARLY FRIDAY WILL QUICKLY BE REPLACED BY A SURFACE TROUGH DURG THE DAY...AS A SFC LOW DEEPENS OVER EASTERN COLORADO IN RESPONSE TO A FAST MOVG H50 SHORTWAVE SKIRTING EAST FM THE NORTHERN ROCKIES INTO THE PLAINS. AS THE SFC PRESSURE GRADIENT TIGHTENS...SOUTH WINDS WILL INCREASE TO 15 TO 20 MPH ON FRI AFTN ESPECIALLY ON THE CAPROCK. THIS WILL FAVOR AREAS ACROSS THE WESTERN CWFA TO WARM SEVERAL DEGS FM THURSDAY...WITH THE REMAINDER OF THE CWFA ONLY EXPERIENCING A SLIGHT RISE. FOR THE WEEKEND...NEAR ZONAL UPPER FLOW WILL SUSTAIN A SFC LEE TROUGH ACRS THE REGION PROMOTING ABOVE NORMAL TEMPS. WARMEST READINGS WILL BE REALIZED SUNDAY AS A H85 THERMAL RIDGE STRENGTHENS OVER WEST TEXAS AHEAD OF THE NEXT UPPER TROUGH/COLD FRONT DROPPING SOUTH FROM THE CENTRAL PLAINS. THIS FRONT IS ON SCHEDULE TO ARRIVE SUNDAY NIGHT WITH TEMPS RETURNING TO NORMAL FOR MONDAY. A WARMING TREND WILL THEN ENSUE TUES AND WED AS AN UPPER RIDGE TRANSLATES THROUGH THE SRN PLAINS. STILL APPEARS THAT THANKSGIVING DAY WILL BE NICE AND MILD...BUT WILL BE WATCHING FOR THE POSSIBLY OF A STRONG STORM SYSTEM DEVELOPING OVER SOUTHERN CALIFORNIA... WHICH COULD BRING SOME WEATHER CHANGES FOR THE REMAINDER OF THE HOLIDAY WEEKEND. && .PRELIMINARY POINT TEMPS/POPS... FRIONA 41 19 53 27 63 / 0 0 0 0 0 TULIA 44 21 50 27 61 / 0 0 0 0 0 PLAINVIEW 46 22 50 27 62 / 0 0 0 0 0 LEVELLAND 49 20 52 26 64 / 0 0 0 0 0 LUBBOCK 49 23 51 29 63 / 0 0 0 0 0 DENVER CITY 49 22 53 27 63 / 0 0 0 0 0 BROWNFIELD 50 21 52 27 64 / 0 0 0 0 0 CHILDRESS 49 26 50 28 62 / 0 0 0 0 0 SPUR 50 22 51 29 63 / 0 0 0 0 0 ASPERMONT 52 22 52 30 64 / 0 0 0 0 0 && .LUB WATCHES/WARNINGS/ADVISORIES... NONE. && $$ 05/21 tx AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BLACKSBURG VA 103 PM EST THU NOV 20 2008 .SYNOPSIS... A COLD FRONT WILL PASS THROUGH THE REGION TODAY. COLDER AIR ARRIVES TONIGHT AND FRIDAY WITH ADDITIONAL MOUNTAIN SNOW SHOWERS LIKELY. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... MORNING SOUNDINGS AROUND THE AREA HAVE WINDS AT 40-50 KNOTS JUST BELOW THE INVERSION LAYER AT 4-5KFT. RUC BUFKIT SOUNDINGS DON`T SHOW THE WINDS GETTING ANY STRONGER. THE WINDS ARE ALREADY GUSTING 37 KTS AT TNB AND WILL BEGIN MIXING SOWN TO THE SURFACE BY 15-16Z. FOR NOW LOOKS LIKE JUST BELOW ADVISORY CRITERIA GUSTS. KRLX RADAR IS STEADILY FILLING IN WITH PRECIPITATION TO THE WEST. ONLY DELAYED ONSET OF SHOWERS IN SOUTHEAST WEST VIRGINIA BY A COUPLE OF HOURS. AT 14Z COLD FRONT WAS OVER THE WESTERN COUNTY WARNING AREA. INCREASED MAXIMUM TEMPERATURES IN MOST LOCATIONS AHEAD OF THE FRONT A FEW DEGREES. && .SHORT TERM /6 PM THIS EVENING THROUGH SATURDAY NIGHT/... FORECAST SOUNDINGS SUGGEST UPSLOPE RH WILL DEEPEN ENOUGH FOR AREAS OF -SHSN WEST...LEADING TO MORE SUBSTANTIAL BANDING LATE AS VORT PASSES. HOWEVER BEST NW FLOW LAKE TRAJECTORY WONT DEVELOP UNTIL TONIGHT/FRIDAY MORNING WHICH MAY COINCIDE WITH LESSENING LOW LEVEL MOISTURE. ELECTED TO POST A WINTER WEATHER ADVISORY FOR GREENBRIER COUNTY. IT WILL ALSO TURN MUCH COLDER TONIGHT WITH THE ARRIVAL OF -12C 85H TEMPERATURES. PLAYED LOW TEMPERATURES CLOSE TO MAV GUID WITH LOWS FROM AROUND 20 TO THE UPPER 20S. SNOWFALL COVERAGE DURING THE DAY FRIDAY WILL SLOWLY BE ON THE DECREASE AS THE TROUGH AXIS SHIFTS EAST OF THE AREA...TAKING THE BEST DYNAMICS WITH IT. DURING THIS TIME...AN ADDITIONAL TWO TO THREE INCHES OF SNOW WILL BE POSSIBLE ACROSS THE HIGHER TERRAIN OF WESTERN GREENBRIER COUNTY...WITH LIMITED SNOW ELSEWHERE IN THE SE WV MOUNTAINS. EXCEPT FOR A FEW LINGERING FLURRIES...THE SNOW IS EXPECTED TO END BY FRIDAY EVENING AS SURFACE HIGH PRESSURE BUILDS INTO THE AREA. ON SATURDAY...A WEAK DISTURBANCE ALOFT WILL BRING AN INCREASE IN MID TO HIGH LEVEL MOISTURE. HAVE INCREASED SKY COVER TO ACCOUNT FOR THIS...BUT WE ARE NOT EXPECTING ANY PRECIPITATION WITH THIS FEATURE. THE CLOUD COVER WILL BE ON THE DECREASE SATURDAY NIGHT AS THE DISTURBANCE MOVES EAST OF THE REGION. TEMPERATURES THROUGH THE PERIOD WILL AVERAGE 10 DEGREES BELOW NORMAL WITH READINGS LIKELY TO BE BELOW GUIDANCE IN AREAS OF SNOW COVER. && .LONG TERM /SUNDAY THROUGH THURSDAY/... BRIEF SPELL OF S/W RIDGING AND WARMING SUNDAY WILL GIVE WAY TO YET ANOTHER 5H TROF AND ITS ASSOCIATED COLD FRONT LATER MONDAY. LOOKS LIKE ENOUGH WARM ADVECTION UNDER INSOLATION TO PERHAPS PUSH ALL AREAS INTO THE 40S WITH SOME 50S EAST SUNDAY...EXCEPT OVER THE NW SNOW COVER WHERE 30S LIKELY TO LINGER. FRONT SLIDES THRU MONDAY NIGHT PER THE SLOWER ECMWF WITH A ROUND OF RAIN SHOWERS THAT MAY SWITCH TO SNOW SHOWERS MOUNTAINS BEFORE TRENDING TOWARD ANOTHER ROUND OF UPSLOPE -SHSN LATER MONDAY NIGHT/TUESDAY. THUS WILL CARRY CHANCE POPS MONDAY INTO MONDAY NIGHT...THEN MAINLY WESTERN ZONES TUESDAY AS MORE S/W ENERGY ROUNDS THRU THE TROF AND ACROSS THE REGION. SHOULD START TO SEE MORE DRYING WED AS THE 5H TROF STARTS TO LIFT OUT AGAIN SO LOW POPS MAINLY FAR WESTERN ZONES FOR THE MOST PART. HIGH TEMPS REMAIN MILD AS COMPARED TO LATE WITH THE FROPA MONDAY...THEN SLOWLY COOL UNDER THE NEXT SHOT OF COLD ADVECTION THRU WED...BRINGING HIGHS BACK INTO THE 30S/LOW 40S WEST TO MID/UPPER 40S EAST OF THE BLUE RIDGE. && .AVIATION /18Z THURSDAY THROUGH TUESDAY/... DRY AIR AND A WESTERLY WIND AT CLD LEVEL HELPING TO TEAR APART SNW SHWS TRYING TO MOVE INTO VIRGINIA. SNW SHWS NOW MAKING IT TO EKN AND THESE WILL SLIP SOUTH AS THE DAY WEARS ON. MAY BEGIN AS A RAIN/SNOW GRAINS (GS) MIX AS IT BEGINS AT LWB LATER THIS PM. AS SHRTWV DIGS THROUGH VA LATE TONIGHT...SNW SHWS PICK UP IN INTENSITY AT LWB BUT MORESO AT BLF...WITH THE MOST RESTRICTIONS...IFR VIS OR CIG OCCURRING FROM 10Z TO 15Z. WINDS MAY ALSO GUST TO 25 KTS AT BLF AND ALSO POINTS EAST WITH DOWNSLOPING COMPONENT THROUGH THE END OF THE TAF PERIOD. DRIER WEATHER EXPECTED SATURDAY AND SUNDAY. ANOTHER COLD FRONT ARRIVES MONDAY WITH CHANCE OF RAIN AND SNOW SHOWERS. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...NONE. NC...NONE. WV...WINTER WEATHER ADVISORY FROM 9 PM THIS EVENING TO 9 AM EST FRIDAY FOR WVZ045. && $$ SYNOPSIS...JH/KK NEAR TERM...AMS SHORT TERM...DS/JH LONG TERM...JH AVIATION...KK/KM va AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE SPOKANE WA 347 PM PST THU NOV 20 2008 .SYNOPSIS... A FAST MOVING COLD FRONT SWEEP THROUGH THE INLAND NORTHWEST THIS EVENING RESULTING IN WIDESPREAD RAIN AND MOUNTAIN SNOWS. ANOTHER QUICK MOVING COLD FRONT WILL BRING MORE PRECIPITATION FRIDAY NIGHT INTO SATURDAY. STRONG HIGH PRESSURE WILL THEN REBUILD BY THE END OF THE WEEKEND RESULTING IN DRIER WEATHER THROUGH EARLY NEXT WEEK. && .DISCUSSION... UPDATED AVIATION DISCUSSION. TONIGHT...STRONG NEGATIVE TILT TROF CONTINUES TO MAKE STEADY PROGRESS THROUGH THE INLAND NORTHWEST. AS OF 22Z...THE BACK EDGE OF THE PRECIPITATION ASSOCIATED WITH THE COLD FRONT EXTENDED FROM SEATTLE TO PENDLETON AND WAS MAKING A STEADY NORTHEAST PROGRESSION AHEAD OF THE UPPER LEVEL TROUGH. WIDESPREAD PRECIPITATION HAS DEVELOPED AHEAD OF THE FRONT...ALBEIT FAIRLY LIGHT...AND SHOULD GRADUALLY INTENSIFY DURING THE EVENING DUE TO OROGRAPHIC ASCENT OVER THE MOUNTAINS OF NE WA AND NORTH ID. THE LATEST RUC SEEMS TO BE HANDLING THE FRONTAL AND UPPER LEVEL TROUGH POSITIONING QUITE WELL AND WILL BE FOLLOWED CLOSELY INTO THE EVENING AND OVERNIGHT HOURS. THIS SOLUTION SUGGESTS THE PRECIPITATION WILL RAPIDLY WIND DOWN OVER THE SOUTHERN COLUMBIA AND INTO THE PALOUSE THIS EVENING AS MUCH DRIER AIR MOVES IN BEHIND THE FRONT. MEANWHILE THE NEGATIVE ORIENTATION OF THE UPPER LEVEL TROF WILL ALLOW SOME WRAP-AROUND MOISTURE TO PERSIST OVER THE NORTHERN TIER OF ZONES. THE TROF AND COLD FRONT WILL PASS THE ENTIRE CWA BETWEEN 06-09Z TONIGHT...WITH ANY PRECIPITATION LIMITED TO POST-FRONTAL SHOWERS PRIMARILY OVER THE NE CORNER OF THE CWA. SNOW LEVELS WILL BE FAIRLY TRICKY AS MODEL GUIDANCE HAS VALUES FAR TOO HIGH THIS AFTERNOON. 850 MB TEMPS HAVE PLUNGED TOWARD 0C ON THE LEADING EDGE OF THE COLD FRONT AND WE HAVE SEEN REPORTS OF SNOW AROUND 2500 FT AT PULLMAN. THIS SUGGESTS MODEL GUIDANCE HAS FORECASTS NEARLY 2000 FT TOO HIGH. THESE CONDITIONS ARE A RESULT OF STRONG COLD AIR ADVECTION AND WET-BULB COOLING AND WE WILL HAVE TO ADJUST ACCORDINGLY THROUGH THE EVENING. WE DO NOT ANTICIPATE ANY WINTER HIGHLIGHTS AS THIS IS A SWIFT MOVING SYSTEM AND QPF VALUES ARE A LITTLE TOO LOW...NOT TO MENTION ANY SNOW THAT FALLS IN THE HIGHER VALLEYS SHOULD READILY MELT. FX FRIDAY THROUGH SATURDAY NIGHT...EXIT OF TODAYS WEATHER SYSTEM STILL INFLUENCING PART OF THE NORTHERN IDAHO PANHANDLE EARLY FRIDAY MORNING WHILE A SECOND LOW PRESSURE SYSTEM...ALSO MAINTAINING A RESPECTABLE TAP INTO SUBTROPICAL MOISTURE AS IT APPROACHES...STARTS TO AFFECT THE CASCADES. THIS LOW PRESSURE SYSTEM AND ITS ASSOCIATED PLUME PASS THROUGH FRIDAY NIGHT AND WITH IT COME THE HIGHEST POPS OF THIS TIME INTERVAL. MOISTURE TAP AND WEATHER SYSTEM CLEAR THE AREA HOWEVER THE RIDGE LEFT BEHIND IN THE WAKE IS NOT AMPLIFIED ENOUGH TO SHUNT ANY SMALLER NUISANCE SHORTWAVES AWAY FROM THE AREA...THUS HAVE KEPT MINOR POPS ALONG THE PERIPHERY AND PRIMARILY OVER THE MOUNTAINS TO CAPTURE ANY MINOR SHOWERS THAT MAY OCCUR WITH PASSAGE SATURDAY INTO SATURDAY NIGHT. FORECAST TEMPERATURES REMAIN ON THE WARM SIDE OF CLIMO GIVEN THE PERSISTENT RIDGE AND ANY MIXING POTENTIAL WITH FRIDAY NIGHTS WEATHER SYSTEM PASSAGE. /PELATTI SUNDAY THROUGH THURSDAY...A MID LEVEL RIDGE WILL BUILD OVER THE REGION ON SUNDAY AND PREVAIL AT LEAST THROUGH TUESDAY. THIS WILL LEAD TO ANOTHER PERIOD OF LOW-LEVEL INVERSIONS AND POOR MIXING WITH RESULTING AIR STAGNATION CONCERNS. WITH LIGHT WINDS AND CLEARING SKIES EXPECT AREAS OF FOG TO DEVELOP IN SOME OF THE VALLEYS. MODELS AGREE ON BRINGING A COUPLE OF WEAK SYSTEMS THROUGH THE REGION BUT DIVERGE ON THE TIMING AND STRENGTH. ONE FRONT SWINGS THROUGH ON MONDAY AND A SECOND ONE ON TUESDAY OR WEDNESDAY DEPENDING ON MODEL CHOICE. BOTH THE GFS AND ECMWF DEPICT A RATHER WEAK SYSTEM ON MONDAY THAT SERVES TO FLATTEN THE RIDGE. THE FRONT LOSES SOME PUNCH AS IT REACHES THE CASCADES WITH PRECIPITATION LIMITED TO THE NORTHWEST PORTION OF THE FORECAST AREA. THE ECMWF FORMS A STRONGER CLOSED LOW OFF THE CALIFORNIA COAST WHICH CAPTURES MOST OF THE ENERGY AND MOISTURE RESULTING IN LITTLE EFFECT OVER THE INLAND NORTHWEST OTHER THAN TO SPREAD SOME HIGH CLOUDS. THE SECOND SYSTEM APPEARS TO HAVE A STRONGER COLD FRONT AND A BETTER CHANCE OF CLEARING OUT THE STAGNANT CONDITIONS AS 850MB WINDS AND MIXING HEIGHTS WILL BE ON THE RISE. RIDGING REBOUNDS BY MIDWEEK WITH THE POTENTIAL FOR MORE AIR STAGNATION CONCERNS. TEMPERATURES WILL CONTINUE TO TREND SLIGHTLY ABOVE SEASONAL NORMALS. /KELCH && .AVIATION... A VIGOROUS COLD FRONT WILL CONTINUE TO PUSH NORTHEAST THROUGH NORTHEAST WASHINGTON AND THE NORTHERN PANHANDLE OF IDAHO THIS EVENING. A BAND OF PRECIPITATION WILL ACCOMPANY THE COLD FRONT AND WILL BRING THE POTENTIAL FOR BRIEF MVFR CEILINGS AND VISIBILITIES TO KGEG...KSFF...KCOE...AND KPUW UNTIL 03Z. IN ADDITION TO THE CLOUDS AND PRECIPITATION...GUSTY SOUTHWEST WINDS ARE EXPECTED TO DEVELOP BEHIND THE FRONT GUSTS AS HIGH AS 30KTS WILL BE POSSIBLE BETWEEN THROUGH 06Z. EXPECT IFR STRATUS FIELDS TO FORM OVERNIGHT AFTER 12Z IMPACTING KGEG...KSFF...AND KCOE. /EK && .PRELIMINARY POINT TEMPS/POPS... SPOKANE 32 43 32 42 27 43 / 80 10 50 10 10 0 COEUR D`ALENE 32 43 33 43 30 43 / 90 10 50 20 10 0 PULLMAN 33 45 36 45 30 46 / 70 10 30 10 10 0 LEWISTON 38 52 38 50 31 51 / 60 0 20 10 10 0 COLVILLE 29 40 31 41 24 39 / 90 10 40 10 10 0 SANDPOINT 32 42 32 40 26 42 / 100 20 50 40 20 0 KELLOGG 33 41 34 40 30 40 / 90 30 50 40 20 0 MOSES LAKE 30 47 31 47 27 45 / 10 0 20 0 0 0 WENATCHEE 32 45 35 45 29 42 / 10 0 20 0 0 0 OMAK 28 43 32 43 26 42 / 20 10 20 0 0 0 && .OTX WATCHES/WARNINGS/ADVISORIES... ID...NONE. WA...NONE. && $$ wa AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LA CROSSE WI 200 AM CST WED NOV 19 2008 .SHORT TERM...TODAY THROUGH FRIDAY NIGHT FORECAST CONCERNS CONTINUE TO FOCUS ON THE FREEZING DRIZZLE POSSIBILITIES THIS MORNING...THEN ANY LINGER PCPN CHANCES FOLLOWED BY COLD AIR FOR THE NEXT COUPLE DAYS. THE POTENTIAL FOR FREEZING DRIZZLE/DRIZZLE CONTINUES THIS MORNING...AND WHETHER OR NOT IT MANIFESTS DEPENDS ON THE AMOUNT OF LOW LEVEL SATURATION. ISENTROPIC UPGLIDE CONTINUES TO BE HEFTY ALONG THE 280-295 K SFCS THOUGH 18Z TODAY...AS DOES THE 925-850 MB WARM AIR ADVECTION...SO AMPLE LOW LEVEL THERMODYNAMICS TO FUEL PCPN. THIS IS ALL AHEAD OF A COLD FRONT...ASSOCIATED WITH A SFC LOW TO THE NORTH...AND A 500 MB SHORTWAVE TROUGH CURRENTLY DROPPING INTO NORTHERN MN. AGAIN THOUGH...SATURATION IS THE QUESTION. A NORTH-SOUTH RUNNING TIME/HEIGHT X-SECTION SHOWS AN INCREASE IN THE SATURATION FROM NORTH TO SOUTH DURING THE DAY TODAY...FROM 850 MB TO THE SFC. THE SATURATED LAYER IS RATHER SHALLOW HOWEVER...GENERALLY ONLY AROUND 2 K FT THICK. MEANWHILE...BUFKIT SOUNDINGS BETWEEN 12-18Z THIS MORNING...WHEN THE THERMODYNAMICS ARE AT THEIR PEAK...STILL POINT TO A NEAR SFC DRY LAYER. CURRENT SFC DEWPOINT DEPRESSIONS WELL OVER 10 DEGREES FOR MUCH OF THE FORECAST AREA...SO CONSIDERABLE MOISTENING OF THIS DRY LAYER WILL NEED TO BE DONE BEFORE PCPN CAN REACH THE SFC. RUC TD DEPRESSIONS IN THE 1000-950 MB LAYER SHOW A DECREASE THIS MORNING...BUT IT LOOKS TO BE TOO LITTLE...TOO LATE. FEEL THIS NEAR SFC/SFC DRY LAYER WILL NOT BE OVERCOME BY THE TIME THE BROADSCALE THERMODYNAMICS MOVE EAST...NOR IS THE CLOUD DEPTH LIKELY TO BE DEEP ENOUGH ACROSS THE LOCAL AREA TO GET A DRIZZLE PROCESS GOING. FARTHER NORTH WILL HAVE A BETTER CHANCE...BUT FEEL THE PROBABILITIES ARE TOO LOW AT THE MOMENT TO INCLUDE IN THE LOCAL FORECAST. OBVIOUSLY THIS WILL HAVE TO BE MONITORED CLOSELY THROUGH THE MORNING HOURS. FOR THE AFTERNOON...THE COLD FRONT WILL HAVE SLID EAST INTO EASTERN WI...WITH A GOOD AMOUNT OF COLD AIR ADVECTION SUB 850 MB POST THE FRONT...WITH A STRONG INVERSION ABOVE THAT. BETTER SATURATION/COLD AIR SHOULD RESULT IN SOME COLD AIR CU/SC FLAT-TOPPED DEVELOPMENT. COULD SQUEEZE OUT A FEW FLURRIES WHERE THE SATURATION IS DEEPEST...IN THE NORTH...BUT DON/T FEEL THERE WILL BE A SNOW SHOWER THREAT AT THIS TIME. TONIGHT TROUGH THURSDAY...THE UPPER MISSISSIPPI RIVER VALLEY WILL STAY UNDER THE INFLUENCE OF CYCLONIC FLOW ALOFT...AS THE 500 MB TROUGH EXITS ACROSS THE NEW ENGLAND. SHORTWAVE ENERGY WILL SPIN ACROSS THE REGION ON THE BACKSIDE OF THIS TROUGH...WHILE AN ASSOCIATED SFC TROUGH ALSO SINKS ACROSS THE AREA. THE 850 MB TO SFC LAYER REMAINS RELATIVELY MOIST TONIGHT...BUT DRYING IN THE SFC LAYER OCCURS ON THU...PER THE BUFKIT SOUNDINGS. 1000-850MB LAPSE RATES JUMP UP TO 9.5 C/KM FOR THU. SO...EXPECT CLOUDS TO HANG AROUND WED NIGHT/THU...WITH CU/SC DEVELOPMENT IN ANY BREAKS ON THU. SOME FLURRIES WILL ALSO BE POSSIBLE THROUGH THIS PERIOD. A SFC HIGH LOOKS TO BUILD ACROSS THE UPPER MISSISSIPPI RIVER VALLEY ON FRIDAY...WHILE A 500 MB SHORTWAVE TROUGH DRIVES SOUTHEAST ACROSS THE NORTHERN PLAINS...INTO IA. 19.00Z NAM AND GFS MODELS RUNS PAINT SOME QPF WITH THIS SHORTWAVE ACROSS THE PLAINS...BUT DIMINISH IT AS IT WORKS INTO THE HIGH. THE SREF SUPPORTS THIS. SO...SOME CLOUDS TO THE WEST AND SOUTH WITH THIS SHORTWAVE...BUT WILL KEEP THE LOCAL AREA DRY FOR NOW. FOR TEMPERATURES...SEASONABLE READINGS CAN BE EXPECTED TODAY...WITH HIGHS LIKELY IN THE MORNING. WITH THE FRONTAL PASSAGE BY NOON FOR MUCH OF THE FORECAST AREA...COLD AIR WILL FLOW IN BEHIND IT... LEADING TO MORE STEADY...EVEN FALLING TEMPS. THE FLUX OF COLD AIR WILL CONTINUE FOR THU...WITH HIGHS STRUGGLING TO REACH FREEZING. IN ADDITION...WINDS WILL BE ON THE INCREASE TONIGHT AND STAY UP FOR THU. WIND CHILLS IN THE UPPER TEENS TO 20S SHOULD RESULT. SKIES WILL START TO CLEAR FROM WEST TO EAST THU NIGHT...WITH DECREASING WINDS. THIS COULD LEAD TO SOME CHILLY FRI MORNING LOWS...WITH SINGLE DIGITS IN SOME LOCATIONS. .LONG TERM...SATURDAY THROUGH TUESDAY MEDIUM RANGE MODELS SHOWING MUCH BETTER AGREEMENT THIS GO AROUND...CONVERGING ON A MORE JOINT SOLUTION...AS OPPOSED TO VARIANCES THAT WERE ALMOST 180 DEGREES OUT OF PHASE WITH EACH OTHER PREVIOUSLY. CLIPPER TYPE SHORTWAVE TROUGH PROGGED TO MOVE EAST OUT OF CANADA...STRENGTHENING AS IT SPINS INTO THE UPPER MISSISSIPPI RIVER VALLEY BY SUNDAY NIGHT. BETTER PCPN CHANCES CURRENTLY LOOK TO BE NORTH OF THE LOCAL AREA AS THIS SYSTEM MOVES THROUGH. INVERTED SFC TROUGH POST THE ASSOCIATED SFC LOW...ALONG WITH CYCLONIC FLOW AND SOME SHORTWAVE ENERGY ALOFT...WILL CONTINUE PCPN CHANCES ON THE BACKSIDE OF THE SYSTEM FOR MONDAY...ALTHOUGH...BETTER CHANCES LOOK TO BE NORTH AND EAST OF THE LOCAL AREA. HIGH PRESSURE WILL THEN BUILD IN FOR TUES/WED. SEASONABLE TEMPERATURES SHOULD RETURN FOR NEW WORK WEEK. && .AVIATION... A SURFACE LOW WAS MOVING INTO WESTERN MINNESOTA THIS MORNING WITH A TRAILING COLD FRONT BACK INTO NEBRASKA. AHEAD OF THIS SYSTEM...SOUTHERLY WINDS HAVE ADVECTED WARMER AIR INTO THE REGION. BIGGEST QUESTION WILL BE THE ONSET OF MVFR CEILINGS AT THE TAF SITES. MODELS SUGGESTING THAT THIS ONSET WILL BE POST FRONTAL...WITH FRONTAL PASSAGE EXPECTED AT AROUND 15Z AT KRST AND 16Z AT KLSE. THUS HAVE KEPT VFR CEILINGS THROUGH MID MORNING WITH MVFR CEILINGS OF 2K-3K FEET FROM LATE MORNING THROUGH THE AFTERNOON. CEILINGS ARE EXPECTED TO LOWER AFTER 00Z THURSDAY BUT REMAIN IN THE MVFR CATEGORY. RATHER GUSTY NORTHWEST WINDS ARE EXPECTED AFTER FRONTAL PASSAGE WITH GUSTS OF 24 TO 30 KNOTS AT BOTH TAF SITES. RABERDING && .ARX WATCHES/WARNINGS/ADVISORIES... WI...NONE. MN...NONE. IA...NONE. && $$ RIECK wi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CHICAGO/ROMEOVILLE IL 111 AM CST FRI NOV 21 2008 .DISCUSSION... 106 AM CST MAIN PLUME OF SNOW THRU THE DAY HAS BEEN ALONG THE EASTERN EDGE OF LK MICHIGAN. DESPITE WEAK TROF PASSAGE DOWN THE LAKE THIS EVENING AND SLIGHT VEERING OF BANDS TO A MORE NORTHERLY TRACK...THE FETCH FOR PORTER COUNTY ONLY APPEARS TO EXTEND FROM OFFSHORE MILWAUKEE. MAY WIND UP GETTING 2 TO 3 INCHES FOR PORTER COUNTY BUT TO CONTINUE CARRYING THE WARNING OR EVEN AN ADVISORY SEEMS TO BE OVERKILL. MODELS INDICATING AS THEY DID IN PREVIOUS RUNS THAT WIND FIELD IS BACKING TO MORE WESTERLY FLOW TOWARD MORNING... TERMINATING THE PRESENT NORTHERLY FETCH. THEREFORE PRUDENCE WUD DICTATE TO CANCEL WARNING. WILL DO SO BEFORE 4AM ISSUANCE THIS MORNING. RLB && .PREV DISCUSSION... 836 PM CST RADAR TRENDS OVER PAST SEVERAL HOURS HAVE CONTINUED TO DEPICT SOMEWHAT DISORGANIZED LAKE EFFECT CONVECTION ACROSS SOUTHERN LAKE MICHIGAN. SOME HIGHER REFLECTIVITY CELLS BEGINNING TO DEVELOP ACROSS FAR SOUTH LAKE MICHIGAN LAST 30 MINUTES OR SO...THOUGH STILL APPEARS MAIN LES AXIS AT THIS TIME IS ALONG EASTERN SHORE AND INTO NORTH CENTRAL INDIANA. NEW 00Z NAM IN THROUGH 48+ HOURS...AND TENDS TO KEEP MAIN CONVERGENT/QPF AXIS OFF TO THE EAST OF PORTER COUNTY...WHICH MAKES ME SUSPECT THAT OUR SNOW AMOUNTS MAY BE A BIT OVERDONE. WHILE HAVE NOWHERE NEAR ENOUGH CONFIDENCE TO DROP ONGOING WARNING FOR PORTER COUNTY...HAVE SHAVED TOTAL SNOW AMOUNTS A BIT MORE TOWARD 5 TO 7 INCHES MAX ACROSS FAR NORTHEAST PORTER COUNTY. OTHERWISE...GOING FORECAST LOOKS GOOD WITH RESPECT TO TEMPS...FLURRIES AND DECREASING CLOUDS FARTHER TO THE WEST OVERNIGHT AND HAVE MADE NO OTHER SIGNIFICANT CHANGES OTHER THAN TO BUMP WIND GUSTS ESPECIALLY THROUGH THIS EVENING. GRIDS OUT AND PUBLISHED. ZFP/WSW UPDATES OUT SHORTLY. RATZER PREVIOUS DISCUSSION... 340 PM CST PRIMARY FORECAST CONCERNS SURROUND LAKE EFFECT SNOW IN NORTHWEST INDIANA AS REINFORCING SHOT OF ARCTIC AIR PLUNGES SOUTH ACROSS THE WESTERN GREAT LAKES TONIGHT. MODELS SHOWING GOOD CONSISTENCY DRIVING SECONDARY UPPER LEVEL SHORTWAVE TROUGH SOUTH INTO THE OHIO VALLEY BY FRI MORNING AND CARVING OUT AN EVEN DEEPER LONG WAVE TROUGH OVER THE EASTERN U.S. THIS OPENS THE DOOR TO ANOTHER BITTERLY COLD AIRMASS FOR NOVEMBER TO SURGE SOUTH INTO THE AREA. H85 TEMPS DROP TO -14 DEG C ACROSS SRN LK MICHIGAN RESULTING IN VERY STRONG THERMAL INSTABILITY WITH LAKE WATER SURFACE TO H850 TEMP DIFFERENCES OF GREATER THAN 20 DEG C. PRIMARY CONCERN IS WHERE LES BANDS WILL SET UP WITH NW FLOW VEERING MORE NORTH AND RISING INVERSION HEIGHTS. LOCAL WRF HINTING AT SIMILAR SCENARIO AS MONDAY NIGHT/EARLY TUES WITH INTENSE MID LAKE BAND WAFFLING SOUTH ENHANCED BY MID LAKE CONVERGENCE AND THEN BLASTS ON SHORE AROUND 03Z WITH 1-3 INCH PER HOUR SNOWFALL RATES FOR A COUPLE OF HOURS. RUC SOMEWHAT SUPPORTIVE OF THIS IDEA AS WELL WITH SOMEWHAT OF AN NORTHEASTERLY BOUNDARY LAYER WIND COMPONENT ALONG THE MI SHORELINE EVIDENT AROUND 03Z. INVERSION HEIGHTS LIFT TO 12 K FEET BY 00Z THIS EVENING PER NAM FORECAST SOUNDING TIME SERIES AND STAYS THERE UNTIL ALMOST 12Z FRI. AT THIS POINT INVERSION THEN COMES CRASHING DOWN AND LOW LEVEL FLOW BECOMES ANTICYCLONIC AS SURFACE RIDGING BUILDS QUICKLY EAST INTO THE MID MISSISSIPPI AND OHIO VALLEYS DURING THE DAY FRIDAY. BEFORE THEN... LOW MOVING OFF THE MID ATLANTIC COAST AND HIGH BUILDING SOUTH ACROSS THE PLAINS ALLOWS GRADIENT WIND TO TURN FROM 320 TO MORE 340-350 MAXIMIZING FETCH DOWN THE LENGTH OF THE LAKE DURING THE NIGHT. WITH THESE FACTORS AT PLAY... WILL UPGRADE GOING LES ADVISORY TO WARNING FOR PORTER COUNTY AS EXPECT SNOWFALL TO VARY FROM 5 TO 9 INCHES ACROSS MUCH OF THE COUNTY. SNOW AMOUNTS WILL TAPER OFF SHARPLY TO THE WEST AND SOUTH AS WOULD EXPECT AN INCH OR LESS AS FAR WEST AS ALONG I-65 BUT UP TO 4 INCHES ALONG THE LAKE-PORTER COUNTY LINE IN INDIANA. INVERSION HEIGHTS LOWER TO ABOUT 3 K FEET BY 13-14Z FRI... AND CORE OF THE COLDEST AIR/LOW LEVEL THERMAL TROUGH MOVING OVERHEAD AND EAST OF NW INDIANA. WINDS ALSO BACK TO MORE NW QUICKLY FRI MORNING... WHICH WILL SHIFT ANY REMAINING MORE SIGNIFICANT LAKE EFFECT SNOW BANDS EAST OF PORTER COUNTY BY MID MORNING LEAVING A FEW FLURRIES BEHIND. ELSEWHERE RELATIVELY QUIET BUT UNSEASONABLY COLD WEATHER FOR THE NEXT 36 HOURS AS LONG WAVE TROUGH BECOMES REINFORCED ACROSS THE EASTERN U.S. UPPER PATTERN REMAINS PROGRESSIVE HOWEVER AND HEIGHTS BUILD OVER THE LOCAL AREA AS THIS TROUGH BEGINS TO LIFT TO THE EAST SAT. THIS WILL ALLOW FOR RETURN WARM AIR ADVECTION IN THE LOW LEVELS. MEANWHILE FAIRLY VIGOROUS UPPER LEVEL VORT MAX STREAKS SE IN NW FLOW ALOFT ACROSS NRN IL AND NW IND LATER ON SAT. WHILE UPPER DYNAMICS FAIRLY IMPRESSIVE WITH THIS FEATURE... LOW LEVEL MOISTURE REMAINS VERY LIMITED AND AT THIS POINT WILL FORECAST CLOUDS BUT NO PCPN. ED F SUNDAY THROUGH THURSDAY SOME MODERATION IN TEMPERATURES BACK TOWARD SEASONABLE NORMS IS EXPECTED BY SUNDAY AS LOW LEVEL SOUTHWEST FLOW STRENGTHENS IN ADVANCE OF DIGGING NORTHERN PLAINS UPPER TROUGH. DESPITE FAIRLY STRONG WARM ADVECTION FORCING...DRY CONDITIONS ARE EXPECTED TO PERSIST DURING THE DAY ON SUNDAY WITH COLUMN INITIALLY QUITE DRY. DESPITE INCREASING HIGH/MID CLOUDINESS ON SUNDAY...TEMPERATURES SHOULD REACH INTO THE MID 40S MOST LOCATIONS. HAVE MAINTAINED MENTION OF CHANCE RAIN/SNOW SHOWERS SUNDAY NIGHT AS UPPER TROUGH AXIS APPROACHES WITH FORECAST SOUNDINGS STILL MARGINAL IN TERMS OF PRECIP TYPE WITH LOW LEVEL WET BULB TEMPERATURES RIGHT AROUND FREEZING. FAIRLY GOOD AGREEMENT IN REGARDS TO UPPER TROUGH EVOLUTION BETWEEN GFS/ECMWF INTO MONDAY...WITH DRYING CONDITIONS EXPECTED MONDAY AFTERNOON AS THE UPPER LOW MOVES OFF TO THE EAST. QUIET CONDITIONS EXPECTED TUESDAY/WEDNESDAY...AND NEXT CONCERN WILL BE POTENTIAL OF NEXT SYSTEM TO AFFECT THE AREA TOWARD THE END OF THE WEEK. WITH INCREASING SPREAD IN NCEP ENSEMBLES TOWARD THE END OF THE WEEK...LARGE RUN TO RUN DEVIATIONS...AND TIMING UNCERTAINTIES AMONG MEDIUM RANGE MODELS...WILL KEEP THANKSGIVING DRY AT THIS POINT. NDM && .AVIATION... 06Z TAFS...SKIES CONTINUE TO SCATTER OUT AND CLEAR JUST ABOUT EVERYWHERE THIS EVENING...EXCEPT OVER THE TERMINALS. BUT TRENDS SHOULD CONTINUE WITH CIGS SCATTERING OUT IN A FEW HRS WITH SKC FOR MOST OF FRIDAY. MID/HIGH CLOUDS QUICKLY ADVANCE TOWARD THE END OF THIS PERIOD INTO EARLY SATURDAY MORNING. PRESSURE GRADIENT WILL SLOWLY RELAX OVERNIGHT...ALLOWING GUSTS TO DIMINISH BUT EXPECT PREVAILING WINDS 10-15KTS TO CONTINUE THRU MID MORNING. A LARGE AREA OF HIGH PRESSURE WILL SLIDE SOUTHEAST...JUST WEST OF NORTHERN IL FRIDAY. THIS WILL ALLOW WINDS TO GRADUALLY TURN WESTERLY BY LATE AFTERNOON AS SPEEDS DIMINISH UNDER 10KTS. WINDS TURN WSW FRIDAY EVENING WITH SPEEDS DIMINISHING TO 5 KNOTS OR LESS FRIDAY EVENING. CMS && .MARINE... 141 PM CST LARGE SPRAWLING HIGH PRESSURE CENTERED NEAR LAKE WINNEPEG THIS AFTERNOON...COMBINED WITH DEEP LOW PRESSURE OVER THE CANADIAN MARITIMES...WAS PRODUCING GALE FORCE NORTHWEST WINDS OVER LAKE MICHIGAN. THE NORTHWEST GALES WILL CONTINUE THROUGH MOST OF THE NIGHT. THE HIGH WILL MOVE SOUTHEAST TO THE LOWER MISSISSIPPI AND LOWER OHIO RIVER VALLEYS BY FRIDAY EVENING...ALLOWING WINDS TO SLOWLY SUBSIDE. THE HIGH WILL CONTINUE MOVING SOUTHEAST...REACHING THE CAROLINAS BY SUNDAY. MEANWHILE A WEAK TROF OF LOW PRESSURE WILL DEVELOP OVER THE PLAINS FRIDAY...THEN DRIFT SLOWLY EAST TOWARD THE MID AND UPPER MISSISSIPPI VALLEY BY SUNDAY. LOW PRESSURE WILL DEVELOP OVER THE WESTERN GREAT LAKES SUNDAY NIGHT. THE LOW WILL DEEPEN AS IT MOVES TO THE EASTERN GREAT LAKES MONDAY. THIS WILL BRING A RETURN OF STRONG...POSSIBLY GALE FORCE... NORTHWEST WINDS TO LAKE MICHIGAN MONDAY. ALLSOPP && .LOT WATCHES/WARNINGS/ADVISORIES... IL...NONE. IN...LAKE EFFECT SNOW WARNING...INZ002 UNTIL 9 AM FRIDAY. LM...GALE WARNING...LMZ080-LMZ261-LMZ362-LMZ364-LMZ366-LMZ563-LMZ565- LMZ567-LMZ669-LMZ671-LMZ673-LMZ675-LMZ744-LMZ745-LMZ777- LMZ779-LMZ868-LMZ870-LMZ872-LMZ874-LMZ876-LMZ878 UNTIL 3 AM FRIDAY. SMALL CRAFT ADVISORY...NEARSHORE WINTHROP HARBOR TO GARY IN UNTIL 6 PM FRIDAY. SMALL CRAFT ADVISORY...NEARSHORE GARY TO MICHIGAN CITY IN UNTIL 6 PM FRIDAY && $$ il AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NORTHERN INDIANA 1225 AM EST FRI NOV 21 2008 .AVIATION... BAND OF LAKE EFFECT SNOW ALONG ERN SHORE OF LM MOVG DUE SOUTH INTO SBN ATTM IS EXPECTED TO BE PERSISTENT OVERNIGHT AS THERE WILL BE LITTLE CHANGE IN WIND FIELDS. THUS EXPECT MOD-HVY SNOW TO CONT AT SBN UNTIL AROUND DAYBREAK WITH PREDOMINANTLY LIFR VSBYS. THE NLY FLOW SHOULD KEEP LAKE EFFECT SHSN WEST OF FWA THROUGH EARLY FRIDAY MORNING. AFTER DAYBREAK LOW LEVEL DRYING AND BACKING WINDS SHOULD DIMINISH BAND OF SNOW SHOWERS WITH REMNANTS DRIFTING EWD DURING THE DAY PSBLY BRIEFLY IMPACTING FWA... FOR NOW JUST CONTD WITH VCSH BUT MAY NEED TO ADD TEMPO MVFR GROUP WITH 12Z TAFS. AT SBN WITH LAKE EFFECT ENDING CONDITIONS SHOULD IMPROVE TO VFR BY AFTN AND CONT THROUGH FRI NIGHT. && .PREV DISCUSSION... /ISSUED 844 PM EST THU NOV 20 2008/ UPDATE... HAVE UPDATED FORECAST TO INCLUDE CASS COUNTY MICHIGAN IN WARNING. LATEST RADAR TRENDS SHOWED THIS AREA UNDER A STRONG BAND SINCE LATE AFTERNOON AND PHONE CALLS INDICATED 3 INCHES HAD FALLEN IN JUST A COUPLE HOURS. UPSTREAM REPORTS TO THE NORTH ALSO INDICATED CLOSE TO 6 INCHES. REMAINDER OF HEADLINES REMAIN UNCHANGED AT THIS TIME BUT SOME GROWING CONCERN FOR NORTHERN ELKHART COUNTY LATER TONIGHT. LATEST RUC13 PAINTS AND INTERESTING PICTURE FOR LAKE BAND EVOLUTION TONIGHT. SHORE PARALLEL SINGLE BAND BEGINNING TO GET MORE ORGANIZED PER REGIONAL RADAR MOSAIC AND IS CURRENTLY ALIGNING ITSELF RIGHT ALONG EASTERN LAKESHORE NORTH OF BENTON HARBOR. WATER VAPOR SHOWING SHORT WAVE PASSING THROUGH THE REGION AND THIS IS DISRUPTING BANDS SLIGHTLY OVER OUR AREA BUT VEERING WINDS BEHIND IT IS HELPING SET UP THE SINGLE BAND. WE ARE ALSO BEGINNING TO SEE A STRONG STREAMER CONNECTION TO LAKE SUPERIOR WHICH SHOULD HELP FUEL THIS BAND OVERNIGHT. RUC13 925MB OMEGA HAS THIS HANDLED WELL WITH ITS DEPICTION OF A WAVE OF STRONG LIFT MOVING SOUTH OVERNIGHT FROM SUPERIOR AND PHASING WITH CURRENT DEVELOPING BAND. THUS GOING FORECAST ON TRACK FOR NOW AND MORE INTENSE BANDS EXPECTED AFTER MIDNIGHT AND INTO FRIDAY MORNING. OF SOME CONCERN IS WHERE THE HEAVIEST SNOW WILL FALL. MODEL OMEGA FIELDS HAVE BEEN DISPLACED A BIT TOO FAR WEST...WHICH WE HAVE NOTED AS A BIAS AT TIMES IN THE MODELS. HOWEVER THIS WAS NOT THE CASE EARLIER THIS WEEK. RADAR TRENDS SUGGEST THAT AT LEAST THROUGH THE NEXT SEVERAL HOURS...EASTERN BERRIEN AND WESTERN CASS COUNTIES IN MICHIGAN ALONG WITH ST. JOSEPH AND WESTERN ELKHART COUNTIES IN INDIANA WILL BE IN THE BULLSEYE OF THIS DEVELOPING BAND. THEREFORE CASS WAS UPGRADED TO THE WARNING AND WE ARE MONITORING TRENDS FOR POSSIBLY UPGRADING ELKHART. SECONDARY BAND COMING ONSHORE INTO SOUTHERN BERRIEN AND LAPORTE COUNTIES HAS BEEN RATHER EFFICIENT WITH ESTIMATED REPORTS OF 3 TO 4 INCHES. OUTSIDE OF HEADLINE AREAS...BANDS HAVE BEEN VERY EFFICIENT AND PRODUCING NARROW AND BRIEF BANDS OF INTENSE SNOWFALL. KFWA REPORTED HEAVY SNOW FOR A FEW MINUTES AND THIS BAND HAS INTENSIFIED LAST HALF HOUR. ADDED SCATTERED SNOW SHOWERS TO EASTERN AREAS WITH UP TO AN INCH POSSIBLE GIVEN THE HEAVY BUT BRIEF NATURE. FURTHER UPDATES MAY BE NEEDED AS THIS BAND BECOMES MORE NORTH SOUTH ORIENTED. SHORT TERM...(TONIGHT THROUGH FRIDAY NIGHT)... LAKE EFFECT SNOW EVENT IN ITS INFANCY ONGOING ACROSS NW INDIANA AND SW MICHIGAN THIS AFTERNOON. MAINLY DISORGANIZED MULTIPLE BANDS WITH LOW QPF AND LITE SNOW AMOUNTS THUS FAR. NEVERTHELESS...SETUP IS UNDERWAY AND COMPARISON OF NAM BUFR SOUNDING WITH ASCENT SOUNDING FROM 16Z OUT OF KSBN MATCHES UP WELL. H85 TEMPS AROUND -10C PRODUCING LOW END DELTA-T OF 16 DEG WITH BASICALLY UNIDIRECTIONAL WINDS BETWEEN 310-330 DEG AT AROUND 20KT. SOUNDING ALSO CONFIRMS SIGNIFICANT COOLING FURTHER ALOFT AT H7 UNDERWAY WITH TEMPS AHEAD OF 12Z MODEL PROGS HAVING FALLEN TO -20C BY 16Z. FOLLOWED NAM12 WITH FORECAST DETAILS WITH ITS GOOD HANDLE ON VERTICAL PROFILE AND CONSISTENCY WITH 12Z RUN. WINDS VEER A LITTLE MORE NORTHERLY AS INSTABILITY INCREASES THIS EVENING AND PEAKS OVERNIGHT WITH MORE COOLING ALOFT INCREASING DELTA T VALUES TO 20C WITH HIGH EQL PEAKING NEAR 15KFT AND EXCELLENT LAKE INDUCED CAPE THROUGHOUT THE GROWTH ZONE. NAM12/RUC DEPICTION OF LAKE EFFECT PLUME CONSISTENT WITH PVS RUNS AND WITH INHERITED FORECAST WITH ALL SIGNS CONTINUING TO POINT TO THE FORMATION OF A DOMINANT BAND OVERNIGHT WITH HEAVIEST IMPACT ALONG NE LAPORTE...BERRIEN...AND ST JOSEPH COUNTIES WITH ADVISORY FURTHER SOUTH ALONG FCST BEST UVM INTO FULTON COUNTY. LAKE INDUCED CAPE BEGINS TO COLLAPSE AFTER 12Z AS WARMER AIR STARTS TO MOVE IN ALOFT HWVR EQL LEVELS REMAIN AOB LOW END OF GROWTH ZONE WITH SOME LAKE INDUCED CAPE THROUGH 21Z PER NAM BFR SOUNDINGS. HOWEVER FETCH IS SHARPLY CUT BEYOND 18Z AS LL WINDS BACK TO WNW. ACCUMULATING SNOW SLACKENS AS IT SHIFTS NORTH WITH BACKING WINDS AND COMES TO AND END ABRUPTLY BEYOND 18Z AS SETUP FALLS APART. WITH CONTINUED CLOUD COVER HIGHS FRIDAY PEAK ONLY NEAR 30. LOWS SATURDAY MORNING COULD BE PROBLEMATIC AS AREAS WITH FRESH SNOW COVER THAT CLEAR OUT BEFORE MORNING COULD COOL MORE THAN GUIDANCE WOULD INDICATE. SFC RIDGE TO THE SOUTH NOW LOOKS TO BE A BIT FURTHER AWAY AND WITH LIGHT GRADIENT WINDS A POSSIBILITY WILL RIDE GUIDANCE FOR LOW TEMPS PRIMARILY IN THE UPPER TEENS. LONG TERM...(SATURDAY THROUGH THURSDAY)... SURFACE HIGH PRESSURE CENTERED OVER THE TN VALLEY WILL BRING A QUIET START TO THE EXTENDED PERIOD. NW FLOW ALOFT WILL BRING WEAK UPPER LEVEL DISTURBANCE INTO THE REGION SATURDAY AFTERNOON. WITH SURFACE HIGH UNDERNEATH...LITTLE MOISTURE AND FORCING TO WORK WITH SO NOTHING MORE THAN AN INCREASE IN CLOUDS FOR NOW. SURFACE HIGH MOVES TO CAROLINA COAST SUNDAY AND NEXT SYSTEM TAKES SHAPE IN THE PLAINS SETTING UP BRISK SW FLOW FOR OUR AREA. FRONT APPROACHES SUNDAY NIGHT BRINGING NEXT CHANCE FOR PRECIP. DECENT AMOUNT OF WAA AHEAD OF THE FRONT WILL BRING PRECIP TYPE INTO QUESTION. DPROG/DT INDICATING GFS FAIRLY CONSISTENT PAST FEW RUNS WITH OUR AREA BEING CLOSE TO RAIN/SNOW THRESHOLD. BUFKIT SOUNDING ALSO SHOWING SHALLOW 1200FT SFC BASED WARM LAYER SO WILL CONTINUE WITH MIX OF RA/SN SUNDAY NIGHT...THEN ALL SNOW MONDAY AFTER FROPA. CYCLONIC NW FLOW IN THE WAKE OF THIS SYSTEM WILL BRING ANOTHER ROUND OF LES MONDAY AND TUESDAY. HIGH PRESSURE AGAIN SETTLES INTO TN VALLEY BY WEDNESDAY BRINGING DRY FCST THROUGH THANKSGIVING DAY. EXPECT TEMPS TO GENERALLY REMAIN AOB NORMAL THROUGH THE PERIOD. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...LAKE EFFECT SNOW WARNING UNTIL 1 PM EST /12 PM CST/ THIS AFTERNOON FOR INZ003-004. LAKE EFFECT SNOW ADVISORY UNTIL 1 PM EST /12 PM CST/ THIS AFTERNOON FOR INZ005-012-014>016. MI...LAKE EFFECT SNOW WARNING UNTIL 1 PM EST THIS AFTERNOON FOR MIZ077-078. OH...NONE. LM...GALE WARNING UNTIL 4 AM EST EARLY THIS MORNING FOR LMZ043-046. && $$ SHORT TERM...LUDINGTON LONG TERM...LOGSDON AVIATION...TAYLOR UPDATE...LASHLEY in AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GOODLAND KS 200 AM MST FRI NOV 21 2008 .DISCUSSION...FORECAST CONCERNS ARE WINDS TODAY FOLLOWED BY TEMPERATURES THE NEXT FEW DAYS. LARGE AREA OF STRATUS CURRENTLY COVERING MUCH OF EASTERN COLORADO IS EXPECTED (PER RUC/NAM 850-800 RH) TO SPREAD EAST INTO WESTERN KANSAS AND SOUTHWEST NEBRASKA DURING THE EARLY PART OF THE DAY AS A SURFACE TROUGH/WEAK WARM FRONT MOVES EAST. AHEAD OF THIS TROUGH SOUTHERLY WINDS WILL INCREASE INTO THE BREEZY/LOW END WINDY CATEGORY BEFORE DECREASING AROUND SUNSET OR SHORTLY BEFORE. TEMPERATURES WILL BE WARMEST ACROSS THE WEST WITH HIGHS IN THE MID TO UPPER 40S WHILE ACROSS THE EAST ONLY NEAR 40/LOW 40S AS THEY REMAIN CLOSER TO THE COLDER RETREATING SURFACE HIGH. WEAK RIDGING AND SURFACE LEE TROUGH DEVELOP SATURDAY WITH TEMPERATURES RETURNING TO ABOVE NORMAL READINGS WITH HIGHS IN THE MID TO UPPER 50S. ANOTHER FRONT MOVES THROUGH THE AREA SATURDAY NIGHT LOWERING SUNDAYS HIGHS JUST A FEW DEGREES WITH READINGS GENERALLY IN LOW 50S WEST...MID/UPPER 50S CENTRAL AND EAST. MONDAY-TUESDAY...UPPER RIDGE CENTERED ALONG THE CONTINENTAL DIVIDE WILL SEPERATE LOW PRESSURE SYSTEMS OVER THE GREAT LAKES AND OFF THE CALIFORNIA COAST. GFS/ECMWF 850 TEMPS SUPPORT CURRENT FORECAST HIGHS IN THE LOW TO MID 50S MONDAY...CLOSER TO 60S TUESDAY. UPPED TUESDAYS TEMPS A BIT GIVEN GOOD AGREEMENT BETWEEN THE ECMWF/GFS 850 TEMPS AND LATEST MEX GUIDANCE. WEDNESDAY-THURSDAY...NO CHANGES MADE. 07 && .AVIATION... FOR THE 06Z TAFS...BAND OF STRATUS HAS FORMED ACROSS EASTERN COLORADO THIS EVENING. MVFR CONDITIONS WERE BRIEFLY REPORTED AT KITR. RUC INDICATES THAT MVFR CEILINGS WILL REMAIN WEST OF KGLD...BUT WILL INDICATE A FEW HOURS OF SCT-BKN CLOUDS AROUND 2500 FEET BASED ON SATELLITE TRENDS. OTHERWISE...CONDITIONS WILL BE VFR THROUGH THE PERIOD AT BOTH KGLD AND KMCK. SURFACE WINDS WILL BECOME SOUTH AT 15-25 KNOTS AFTER 14Z. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...NONE. NE...NONE. CO...NONE. && $$ ks AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LAKE CHARLES LA 1142 PM CST THU NOV 20 2008 .AVIATION... COLD FRONT HAS JUST PUSHED OFF THE COAST WITH GUSTY NORTH WINDS NOTED AREAWIDE. A BKN-OVC DECK BETWEEN 2000 AND 5000 FT IS SPREADING SOUTHWARD BEHIND THE FRONT. BRIEF MVFR CIGS ARE POSSIBLE AT TAF SITES..BUT SKIES BECOMING SCT BY 08Z AT KAEX AND BETWEEN 09 AND 12Z AT KBPT...KLCH...KLFT AND KARA. NORTH WINDS 15 TO 20 KNOTS WITH GUSTS OF 22 TO 28 KNOTS WILL PERSIST OVERNIGHT...GRADUALLY SUBSIDING DURING THE DAYTIME FRIDAY. VFR CONDITIONS EXPECTED. 24 && .PREV DISCUSSION... /ISSUED 812 PM CST THU NOV 20 2008/ UPDATE...THE STRONG CANADIAN COLD FRONT IS TRACKING RAPIDLY SOUTHWARD THROUGH THE LAKES AREA OF SOUTHEST TEXAS AND CENTRAL LOUISIANA. MOVEMENT IS SOUTH AT 20 MPH. BOTH THE FORT POLK AND LAKE CHARLES RADARS SHOW THIS BOUNDARY WELL. AT THE CURRENT SPEED, THE COLD FRONT SHOULD REACH THE COAST BY 11 PM. WILL HOLD OFF ON ANY LAKE WIND ADVISORIES PER LATEST MAV GUIDANCE AND FORT POLK VAD WINDS BUT HAVE LOWERED EXPECTED MORNING TEMPERATURES TO AROUND 40 DEGREES FOR THE I-10 CORRIDOR AND THE MID 30S ACROSS THE NORTHERN TIER. THIS IS IN RESPONSE TO UPSTREAM DEW POINTS BEHIND THE FRONT THIS AFTERNOON RANGING FROM 26 TO 34 DEGREES. GUIDANCE WILL TYPICALLY OVERSHOOT TEMPERATURES ON AIRMASSES SUCH AS THIS ONE WITH ARCTIC ORIGINS. FORTUNATELY, THE ARCTIC AIR WILL REMAIN POISED NORTH OF THE OHIO VALLEY AND THE COLD DOME OF HIGH PRESSURE WILL DOMINATE THE TENNESSEE VALLEY THIS WEEKEND. MARINE...THE LATEST RUC AND NAM GUIDANCE GIVES SUSTAINED 30 KNOTS UNDER STRONG COLD ADVECTION TO THE WATERS. FELT IT PRUDENT TO GO WITH A GALE WARNING FOR FREQUENT GUSTS TO 35 KNOTS DURING THE PEAK HOURS FOR WINDS BETWEEN 3 AM AND 8 AM. THE REMAINING SMALL CRAFT ADVISORIES LOOK GOOD. PREV DISCUSSION... /ISSUED 541 PM CST THU NOV 20 2008/ AVIATION... COLD FRONT CONTINUES TO PUSH SOUTHEAST TOWARD THE AREA...LOCATED JUST NORTH OF THE LAKES AREA OF EAST TEXAS TO CENTRAL LA. FRONT TO PASS ACROSS KAEX BY 01Z...REACHING THE SOUTHERN TAF SITES BY 03Z. WINDS WILL SHIFT NORTH AND INCREASE WITH THE FROPA. WINDS EXPECTED TO INCREASE TO BETWEEN 15 AND 20 KNOTS WITH GUSTS TO AROUND 25 KNOTS BY MIDNIGHT...ESPECIALLY ACROSS SOUTHERN AREAS. COULD ALSO SEE SOME CLOUDS ALONG AND BEHIND THE FRONT...WITH A BRIEF PERIOD OF BKN CIGS AROUND 4000 FT. SKIES WILL CLEAR BY SUNRISE BUT WINDS WILL BE SLOW TO SUBSIDE THROUGH TOMORROW AFTERNOON. 24 PREV DISCUSSION... /ISSUED 423 PM CST THU NOV 20 2008/ (FCSTR 13) DISCUSSION... COLD FRONT CURRENTLY NEAR A SHREVEPORT TO COLLEGE STATION LINE AND MAKING GOOD SOUTHEAST PROGRESS. BOUNDARY EXPECTED TO HAVE CLEARED THE CWA BY MIDNIGHT...CONTINUING TO PROGRESS THROUGH THE COASTAL WATERS THEREAFTER. MUCH COOLER AND DRIER AIR WILL FILTER IN BEHIND THE FRONT...WITH GUSTY NORTH WINDS EXPECTED TO DEVELOP AS THE FRONT PASSES. WINDS WILL BE NEAR LAKE WIND ADVISORY CRITERIA...BUT THE SETUP IS NOT AS FAVORABLE HERE WITH THE H925 AND SFC WINDS NOT QUITE AS WELL ALIGNED AS THEY ARE FARTHER TO THE NORTH. FRONTAL PASSAGE CONTINUES TO LOOK LARGELY DRY...AND HAVE HELD ONTO JUST THE SLIGHT CHANCE OF -RW OVER THE COASTAL WATERS TONIGHT. OTHERWISE...MAINLY JUST CLOUD COVER TO CONTEND WITH. AMID STRONG CAA REGIME...UNDERCUT GUIDANCE ACROSS THE BOARD AS TEMPERATURES TOMORROW WILL STRUGGLE TO REACH THE MID 50S. TOMORROW NIGHT WILL BE THE COLDEST OF THIS SEVEN DAY FORECAST...AND GIVEN THE BONE DRY AIR SHOWN BY THE MODELS...AGAIN WILL CUT UNDER GUIDANCE NUMBERS. THIS RESULTS IN FREEZING TEMPERATURES FOR MOST OF THE AREA ALONG AND NORTH OF I-10...AND A HARD FREEZE OVER PARTS OF CENTRAL LOUISIANA. CONSIDERED A FREEZE WATCH PRODUCT TO ADVERTISE THIS...BUT WOULD PREFER TO BE DONE WITH THE HAZARDS ASSOCIATED WITH THE IMMEDIATE FRONTAL. WILL HIGHLIGHT IN THE HWO INSTEAD. THIS AIRMASS WILL BE SHORT LIVED AS THE GFS AND ECMWF CONTINUE TO DEPICT A WARM/MOIST AIR REGIME SETTING UP BY SATURDAY NIGHT...AND CONTINUING INTO MONDAY AHEAD OF YET ANOTHER FRONT. CURRENT FORECAST OF SLIGHT CHANCE TO LOW END CHANCE POPS CONTINUES TO LOOK SUFFICIENT AT THIS TIME. FORECAST FOR MID TO LATE PART OF THE WEEK WAS A BLEND OF THE 06Z GFS AND TWO LATEST ECMWF RUNS...WHICH HAVE TEMPERED THE COOLDOWN BEHIND THE FRONT MONDAY...AND THEREAFTER SHOW A WARNING TREND UNDER WEAK RIDGING ALOFT. MARINE... A STRONG COLD FRONT WILL PUSH THROUGH THE COASTAL WATERS OVERNIGHT TONIGHT...WITH GUSTY OFFSHORE WINDS AND ROUGH SEAS EXPECTED THROUGH FRIDAY AFTERNOON. SMALL CRAFT ADVISORIES REMAIN IN PLACE. WINDS AND SEAS WILL REMAIN MODERATE AS ONSHORE FLOW RETURNS BY THE END OF THE WEEKEND...WITH AN INCREASING CHANCE OF RAIN EARLY NEXT WEEK. && .PRELIMINARY POINT TEMPS/POPS... KLCH 40 54 32 61 49 / 10 0 0 0 10 KBPT 40 54 35 61 51 / 10 0 0 0 10 KAEX 34 51 27 58 41 / 10 0 0 0 10 KLFT 40 53 30 61 46 / 10 0 0 0 10 && .LCH WATCHES/WARNINGS/ADVISORIES... LA...NONE. TX...NONE. GM...SMALL CRAFT ADVISORY UNTIL 6 PM CST FRIDAY FOR THE FOLLOWING ZONES: WATERS FROM CAMERON, LA TO HIGH ISLAND, TX EXTENDING FROM 20 NM TO 60 NM...WATERS FROM INTRACOASTAL CITY, LA TO CAMERON, LA EXTENDING FROM 20 NM TO 60 NM...WATERS FROM LOWER ATCHAFALAYA RIVER TO INTRACOASTAL CITY, LA EXTENDING FROM 20 NM TO 60 NM. SMALL CRAFT ADVISORY UNTIL 12 PM CST FRIDAY FOR THE FOLLOWING ZONES: CALCASIEU LAKE...SABINE LAKE...VERMILION BAY. SMALL CRAFT ADVISORY UNTIL 3 PM CST FRIDAY FOR THE FOLLOWING ZONES: COASTAL WATERS FROM CAMERON, LA TO HIGH ISLAND, TX OUT 20 NM...COASTAL WATERS FROM INTRACOASTAL CITY TO CAMERON, LA OUT 20 NM...COASTAL WATERS FROM LOWER ATCHAFALAYA RIVER TO INTRACOASTAL CITY, LA OUT 20 NM. && $$ la AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE MARQUETTE MI 1215 AM EST FRI NOV 21 2008 UPDATED AVIATION SECTION FOR 06Z TAF ISSUANCE .UPDATE... ISSUED AT 1010 PM EST WEAK SHORTWAVE PUSHING ACROSS THE AREA THIS EVENING LED TO AN INCREASE IN THE LK EFFECT OVER WRN CWA...ESPECIALLY FM HIGHER TERRAIN OF ONTONAGON COUNTY INTO BARAGA COUNTY. IR SATELLITE INDICATES ENHANCEMENT IS BEGINNING TO DIMINISH THOUGH. HEAVY LK EFFECT OVR CNTRL COUNTIES PRETTY MUCH STAYED STEADY STATE WHILE THIS SHORTWAVE MOVED THROUGH. POUNDING CONTINUES OVR NW QUARTER OF DELTA COUNTY...WITH STORM TOTALS FM ROCK TO CORNELL TO NEAR GLADSTONE WELL OVR A FOOT. WINDS HAVE GRADUALLY BACKED THIS EVENING AS SHORTWAVE PASSED THROUGH AND THIS RESULTED IN HEAVIEST SNOW SHIFTING TO THE EAST OF MARQUETTE COUNTY WITH ALGER INTO SCHOOLCRAFT AND WRN LUCE NOW IN THE HEAVIER SNOW SHOWERS AND SQUALLS. AM GOING TO LEAVE CURRENT HEADLINES ALONE. THOUGHT ABOUT DROPPING MARQUETTE AS OVERALL SCOPE OF SNOW SHOWERS HAS DIMINISHED CONSIDERABLY. HOWEVER...CONSIDERING ISOLATED HEAVIER SNOW SHOWERS STILL EXIST OVR THE WRN SECTIONS OF MARQUETTE INTO BARAGA WILL STILL HAVE TO PUSH ACROSS THROUGH THE NIGHT...ALONG WITH GUSTY NW WINDS AND BLSN...KEPT THE WARNING GOING. ADDITIONAL SNOW AMOUNTS SHOULD NOT GET TOO OUT OF HAND THOUGH FOR MARQUETTE COUNTY AS BANDS WILL REMAIN ON THE MOVE. WARNINGS IN THE EAST SHOULD WORK OUT FINE. DID TWEAK SNOW AMOUNTS DOWN IN LUCE COUNTY TIL AFTER MIDNIGHT ONCE LOW LEVEL WINDS BACK MORE TO THE NW. OTHERWISE...PARTIAL LK NIPEGON CONNECTION TO THE SNOW SHOWERS AND STRONG WINDS WILL CONTINUE TO PROPEL STRONGER SNOW SHOWERS ALL THE WAY TOWARD THE LK MICHIGAN SHORELINE. WINDS BACKING NW WILL FINALLY END THE HIGHLY UNUSUAL HEAVY LK SUPERIOR LK EFFECT EVENT OVR WRN DELTA COUNTY. && .SYNOPSIS... 12Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW COLD NNW FLOW (12Z H85 TEMPS RANGE FM -18C AT YPL TO -14C AT GRB) OVER THE RELATIVELY WARM WATERS OF LK SUP (WATER TEMPS RANGE FM 5C OVER THE W TO 8C IN THE E) BTWN ARCTIC HI PRES OVER SCNTRL CAN AND LO PRES IN SE CAN. NMRS LES BANDS ARE EVIDENT OVER MAINLY THE E HALF OF THE LK. A LOOK AT 12Z RAOBS SEEMS TO INDICATE WHY THE LES IS HEAVIEST OVER THIS PORTION OF THE LK. SHALLOW CLDS OVER WRN LK SUP IS WHERE STABILITY IS HIER/AIRMASS DRIER PER 12Z INL RAOB...WHICH SHOWS INVRN BASE AT H9 UNDER BONE DRY MID LVLS. ALTHOUGH 12Z YPL RAOB INDICATES INVRN BASE NEAR H9 AS WELL...THAT SDNG SHOWS MSTR THRU H7. SO LES BANDS OVER THE E HALF OF THE LK ARE MUCH MORE WELL DVLPD...ESPECIALLY THE BAND FED BY APRNT MOISTENING OFF LK NIPIGON. 16Z TAMDAR SDNG FM SAW SHOWS INVRN BASE ARND H85...BUT TEMPS WITHIN THE MIXED LYR ARE IN THE -10C TO -17C RANGE AND QUITE FVRBL FOR DENDRITIC SN GROWTH. SO SN IS OF A VERY FLUFFY NATURE WITH HIER SN/WATER RATIOS. THE BANDS HAVE WEAKENED SOMEWHAT DURING THE DAY WITH DAYTIME HTG DIMINISHING THE SHARPER LAND BREEZE CNVGC THAT ACCOMPANIES A WSHFT TO MORE NW OVER LAND DURING NOCTURNAL COOLING. OTRW...A SHRTWV APPEARS TO BE DIGGING SWD THRU ONTARIO ARND CLOSED LO NEAR JAMES BAY. && .SHORT TERM DISCUSSION (TONIGHT AND FRI)... MAIN FCST CONCERNS ARE LES TRENDS/AMTS/GOING HEADLINES. FOR TNGT...SHRTWV OVER ONTARIO PROGGED TO SWING SEWD ACRS THE ERN ZNS AND TO NE LK HURON BY 12Z FRI. LLVL WINDS ARE PROGGED TO BACK MORE NW THRU THE NGT IN RESPONSE TO THIS TRACK. THIS SHRTWV MOTION WL SUPPORT HIER INVRN BASE/DEEPER MOIST LYR OVER THE ERN CWA (DOWNWIND OF YPL)...WITH LOWER INVRN HGT LIKELY OVER THE W UNDER HIER HGTS (DOWNWIND OF INL). H85 TEMPS PROGGED TO FALL A DEGREE OR TWO DURING THE NGT...SO THERMAL PROFILE WITHIN MIXED LYR WL REMAIN FVRBL FOR HIER SN/WATER RATIOS. SO...LARGER SCALE FACTORS FAVOR A CONTINUATION OF HEAVY LES OVER THE E WITH LESSER INTENSITY OVER THE W. MOST LIKELY FOCUS FOR REALLY HEFTY AMTS WL BE INITIALLY OVER THE CNTRL FM MQT-ESC...WHERE HIER RES LOCAL WRF-ARW/RUC13 MODELS HINT AT SHARPEST H925 CNVGC THRU 03Z. AS THE LARGER SCALE WINDS BACK MORE NW...THE MORE FVRBL LLVL CNVGC WL DRIFT TO THE E. DVLPMNT OF LAND BREEZE OFF THE WCNTRL HIER TERRAIN...WHERE TEMPS WL BE LOWEST TNGT...WL TEND TO REINFORCE THE INTENSITY OF THE WRN-MOST BAND. MOISTENING OFF LK NIPIGON WL CONT TO ENHANCE THIS BAND AS WELL. HINT OF LAND BREEZE OFF ONTARIO... MORE VEERED WIND OVER THE ERN U.P... MIGHT HAVE THE SAME IMPACT IN LUCE COUNTY. ON FRI...ANOTHER SHEARED OUT SHRTWV WL APRCH FM THE NW AND PASS OVER THE ERN COUNTIES DURING THE DAY. AS WL BE THE CASE TNGT...INVRN HGT/ DEPTH OF MOIST LYR WL REMAIN HI OVER THE E ON THE CYC TRACK OF THIS SHRTWV TRACK BUT QUITE A BIT LOWER OVER THE W. EXPECT THE HEAVIEST LES OVER THE E UNDER THIS HIER INVRN WITH LLVL FLOW ALSO SLOWLY BACKING MORE NW. 12Z NAM/RUC13/WRF-ARW HINT AT SHARP LLVL CNVGC OVER LUCE/ERN ALGER/SCHOOLCRAFT COUNTIES...SO GOING WRNGS THERE LOOK ON TRACK EVEN IF LAND BREEZE CNVGC FADES A BIT THRU THE DAY. OVERALL... GOING ADVYS/ HEADLINES SEEM APPROPRIATE. ONLY PSBL UPDATE TO HEADLINES MAY BE NECESSITY OF WRNG FOR SRN SCHOOLCRAFT COUNTY AND ABILITY TO CANX ADVY EARLY OVER THE W. COORDINATED WITH APX. .LONG TERM DISCUSSION (FRI NGT THRU THU)... DEPARTING MID LEVEL SHORTWAVE EXITS EASTERN CWA OVERNIGHT FRIDAY. EXPECT SOME LES TO LINGER ACROSS EASTERN ALGER AND LUCE COUNTIES THROUGH SUNRISE AS PROGGED NAM/GFS 925-850 DEWPOINT DP REMAIN LESS THAN 7 THROUGH THE AFTERNOON. WINDS LOOK TO TURN OFFSHORE BY 15Z...CUTTING OF LAKE EFFECT PROCESSES. HIGH PRESSURE WILL WORK ACROSS THE FA EARLY SATURDAY...AS THE HIGH SHIFT EAST OF LAKE SUPERIOR ON SATURDAY AFTN DRY SOUTHERLY FLOW KICKS IN. DID ADD IN SLIGHT CHANCE FOR FREEZING DRIZZLE BETWEEN 6Z AND 12Z SUNDAY AS LATEST BUFKIT PROFILES INDICATE SHALLOW MOISTURE BELOW 5KFT REMAINS WARMER THAN -10C ISOTHERM. .SUNDAY THROUGH TUESDAY MORNING...NEXT SYSTEM OF INTEREST WILL IMPACT THE FA SUNDAY NIGHT THROUGH LATE MONDAY. LOW PRESSURE IS PROGGED TO MOVE ACROSS THE NORTHERN CANADIAN PRAIRIES ON SUNDAY THEN DROP SOUTHEAST AND DEEPEN AS IT MOVES ACROSS THE UPPER GREAT LAKES ON MONDAY. LONG RANGE MODELS...ECMWF/GFS/GLBL-GEM...DISAGREE WITH OVERALL MOISTURE FIELDS...WHICH APPEARS MAINLY TO BE A FUNCTION OF THE UPSTREAM RIDGING. FLATTER 500MB RIDGE SUNDAY NIGHT IN ECMWF SOLUTION ALLOWS SYSTEM TO DROP FURTHER SOUTH. WHILE BOTH THE GFS AND GLBL-GEM HAVE MUCH BETTER DEFINED 500MB RIDGE EXTENDING BACK INTO HUDSON BAY. THE RESULT OF THIS MASS FIELD DIFFERENCE ALLOWS THE ECMWF LOW TO TRACK FURTHER SOUTH AND BE MORE PROGRESSIVE AND WEAKER...WHILE THE GFS/GLBL-GEM SOLUTIONS TRACK DIRECTLY OVER THE FCST AREA WITH A STRONGER/SLOWER PROGRESSION. AS FAR AS DETAILS GO...THIS TRANSLATES TO A HIGH IMPACT SYNOPTIC SNOW EVENT IN GFS WORLD AND A LOW IMPACT LES EVENT IN THE ECMWF SOLUTION. A QUICK LOOK AT SOME OF THE MASS FIELDS SHOWS MORE DIFFERENCES. LATEST ECMWF(12Z)...SHOWS GOOD MID LEVEL CONVERGENCE (PER 700-500MB DIVQ) THOUGH DEEP MOISTURE REMAINS EAST AND SOUTH OF THE FA. THE MORE BULLISH GFS SHOWS DEEP MOISTURE IS BETTER CO-LOCATED WITH BEST MID LEVEL CONVERGENCE FROM LATE SUNDAY NIGHT THROUGH MONDAY NIGHT AS THE LOW TRACKS DIRECTLY OVER THE U.P. FROM THEIR INITIALIZATION ITS HARD TO COME UP WITH ANY DIFFERENCE THAT WOULD LEAD TO THE VARYING SOLUTIONS. THUS HAVE MAINTAINED LOWER POPS THROUGHOUT. .TUESDAY MORNING THROUGH THURSDAY...TEMPORARY RIDGING WILL WORK ACROSS THE FA ON TUESDAY AND WEDNESDAY...ALLOWING TEMPERATURES TO TEMPORARILY WARM UP...THOUGH DON/T EXPECT TEMPERATURES TO QUITE REACH 40. TEMPERATURES ON THURSDAY ARE A VERY UNCERTAIN AT THIS POINT. 850MB TEMPS ARE AROUND -6 TO -8C IN THE GFS AND 0 TO +2C IN THE 12Z ECMWF SOLUTION...THIS DISCREPANCY IS DUE IN PART TO THE MODEL DIFFERENCES WITHIN THE PREVIOUS SYSTEM. THE NEXT SYSTEM BEGINS DIGGING INTO THE UPPER MISSISSIPPI VALLEY THURSDAY EVENING. BOTH THE GFS AND GLB-GEM AGREE WITH TIMING...THOUGH THERE ARE SIGNIFICANT STRENGTH DIFFERENCES. ECMWF SOLUTION KEEPS THIS SYSTEM OVER NORTHERN ONTARIO AND NORTH OF THE LAKES ALTOGETHER. && .AVIATION (FOR THE 06Z TAF ISSUANCE)... WINDS BACKING TO THE NORTHWEST WILL ALLOW LK EFFECT SNOW SHOWERS TO MAINLY IMPACT CMX OVR THE NEXT 24 HRS. IN GENERAL...EXPECT MVFR CIGS AND VSBY IN THE SNOW SHOWERS. ISOLD HEAVIER BANDS OF SNOW SHIFTING ACROSS MARQUETTE COUNTY MAY IMPACT SAW THE REST OF TONIGHT WITH BRIEF IFR VSBY/CIGS...BUT OTHERWISE SNOW SHOWERS SHOULD END AT SAW BY FRIDAY MORNING AS NW WINDS ARE UNFAVORABLE FOR SNOW SHOWERS THERE. HOWEVER AS INVERSION LOWERS ON FRIDAY AND LOW LEVEL MOISTURE PERSISTS...THERE COULD BE STILL BE CIGS IN THE MVFR CATEGORY AT SAW. && .MARINE (FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)... LOOK FOR LAKE SUPERIOR TO REMAIN SANDWICHED BETWEEN LOW PRESSURE OVER NEW ENGLAND AND HIGH PRESSURE BUILDING INTO THE NORTHERN PLAINS THROUGH FRIDAY AFTERNOON. AS A RESULT OF THIS STRONG PRESSURE GRADIENT...NORTH-NORTHWEST GALE FORCE WINDS TO 35 KNOTS ARE EXPECTED ACROSS NORTH CENTRAL AND EASTERN LAKES SUPERIOR THROUGH TONIGHT...WINDS WILL DIMINISH TO 30 KNOTS FRIDAY MORNING THROUGH FRIDAY AFTERNOON. NORTH-NORTHWEST WINDS WILL REACH NEAR GALE FORCE SUNDAY NIGHT INTO MONDAY ACROSS THE EAST HALF OF THE LAKE. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... LAKE EFFECT SNOW ADVISORY UNTIL 7 AM EST /6 AM CST/ FRIDAY FOR MIZ001>004-009-084. LAKE EFFECT SNOW WARNING UNTIL 10 PM EST FRIDAY FOR MIZ006-007- 085. LAKE EFFECT SNOW WARNING UNTIL 10 AM EST FRIDAY FOR MIZ005. LAKE EFFECT SNOW WARNING UNTIL 1 PM EST FRIDAY FOR MIZ013-014. LAKE SUPERIOR... GALE WARNING UNTIL 5 AM EST FRIDAY FOR LSZ266-267. GALE WARNING UNTIL 4 AM EST FRIDAY FOR LSZ265. GALE WARNING UNTIL 1 AM EST FRIDAY FOR LSZ243>245-264. GALE WARNING UNTIL 3 AM EST FRIDAY FOR LSZ249-250. LAKE MICHIGAN... NONE. && $$ UPDATE...JLA SYNOPSIS/SHORT TERM...KC LONG TERM...PEARSON AVIATION...JLA MARINE...PEARSON mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI 1200 AM EST FRI NOV 21 2008 .AVIATION... DRY NORTHWEST WINDS WILL FOSTER A CLEARING TREND EARLY THIS MORNING. VFR CONDITIONS WILL THEN CONTINUE UNTIL CLOUDS INCREASE AGAIN THIS AFTERNOON AS DAYTIME HEATING TRIES TO WARM OUR ABNORMALLY COLD AIR MASS. ANOTHER ROUND OF SCATTERED SNOW SHOWERS IS EXPECTED AS WELL, SIMILAR TO YESTERDAY, WHICH COULD RESULT IN A PERIOD OF MVFR CEILING AND VISIBILITY DURING THE EARLY AND MID AFTERNOON. ALSO LIKE YESTERDAY, EXPECT NORTHWEST WINDS WILL GUST ONCE AGAIN UP TO AROUND 20 KNOTS AT ALL LOCATIONS. THE AFTERNOON WEATHER PATTERN WILL THEN BE FOLLOWED BY A CLEARING TREND THIS EVENING AS HIGH PRESSURE APPROACHES FROM THE WEST. && .PREV DISCUSSION...ISSUED 938 PM EST THU NOV 20 2008 UPDATE... AS COVERAGE OF INLAND SNOW SHOWERS CONTINUES TO DIMINISH THIS EVENING, CONCERN FOR LAKE EFFECT SNOW REMAINS IN THE THUMB. SURFACE ANALYSES OVER THE LAST FEW HOURS SHOW THE WINDS STRONGLY BACKED TO THE NORTHWEST OVER WESTERN PORTIONS OF THE LAKE ALL THE WAY UP TO PRESQUE ISLE, AND THIS HAS KEPT ACTIVITY OFFSHORE FOR MUCH OF THE EVENING. HOWEVER, THE LATEST MODEL DATA IS NOT CONVINCING THAT THIS WILL LAST ALL NIGHT AND TEND TO AGREE AS THERE IS STILL AN OPPORTUNITY FOR THE LOW LEVEL WIND FIELD TO VEER AS A SHORT WAVE ROTATES THE REST OF THE WAY THROUGH LOWER MICHIGAN OVERNIGHT. AT THE SAME TIME, IT WILL TAKE A FEW MORE HOURS FOR THIS TO OCCUR, SO ANY ENCOUNTER WITH EASTERN SECTIONS OF HURON COUNTY WILL BE SHORTER IN DURATION BEFORE THE WINDS BACK MORE STRONGLY TO THE WEST TOWARD SUNRISE. FOR NOW, WE WILL DOWNGRADE TO AN ADVISORY TO ACCOUNT FOR THE ONGOING LENGTHY BREAK IN THE ACTION AND CALL FOR MORE OF A 3 TO 5 INCH ADDITIONAL ACCUMULATION DURING THE EARLY MORNING HOURS. PREV DISCUSSION...ISSUED 352 PM EST THU NOV 20 2008 SHORT TERM...TONIGHT MAIN LAKE BAND OVER SOUTHERN LAKE HURON PROVIDED JUST A GLANCING BLOW TO THE EASTERN THUMB COASTLINE LATE THIS MORNING...WITH JUST A COUPLE INCHES REPORTED ALONG THE SOUTHEAST COAST OF HURON COUNTY BEFORE THE BAND PUSHED OFFSHORE. NOT READY TO GIVE UP ON THE REMAINING NORTHERLY BAND(S) NOTED OVER WESTERN LAKE HURON...AS CLOUD TOPS ARE STILL 8-10 KFT BASED OFF THE APX RADAR. LOW LEVEL WINDS OVER THE NORTH HALF OF LAKE HURON AND OVER EASTERN NORTHERN LOWER MICHIGAN HAVE BECOME A BIT MORE NORTHWEST...WHICH WILL ALLOW THE BAND(S) TO PUSH FARTHER OFFSHORE...BUT STILL BELIEVE FAR EASTERN HURON COUNTY WILL GET CLIPPED THROUGH TONIGHT...WITH ANOTHER 3 TO 6 INCHES EXPECTED ALONG THE SHORELINE....WHICH HAS SOME SUPPORT FROM THE 18Z RUC13...AS 925 MB OMEGA REALLY RAMPS UP LATE THIS EVENING OVER EASTERN HURON COUNTY. AS WAS THE CASE TODAY...THE EVENING SHIFT WILL HAVE TO KEEP CLOSE TABS ON EASTERN SANILAC COUNTY. LITTLE IF ANY SNOW ACCUMULATION EXPECTED WEST OF M-53. OUTSIDE OF THE EASTERN THUMB REGION...DIURNALLY ENHANCED FLURRIES/LIGHT SNOW SHOWERS SHOULD DISSIPATE AND RECEDE CLOSER TO LAKE MICHIGAN WITH THE UNFAVORABLE NNW FLOW...WITH SKIES AT LEAST BECOMING PARTLY CLOUDY...ALLOWING MINS TO DIP DOWN INTO THE UPPER TEENS TO LOWER 20S...DESPITE SURFACE WINDS FAILING TO DECOUPLE. LONG TERM...FRIDAY THROUGH THURSDAY COLD WEATHER PATTERN WILL PERSIST...BY AND LARGE...THROUGHOUT THIS FORECAST PERIOD. TO START THE DAY FRIDAY...A BULK OF THE LAKE EFFECT ACTIVITY WILL OFFSHORE OVER THE MIDDLE OF LAKE HURON. HOWEVER...THE TIP OF THE THUMB MAY RECEIVE ADDITIONAL LIGHT SNOW AMOUNTS DURING THE MORNING. A WEAK SHORTWAVE WILL BE WORKING THROUGH THE AREA AT THE SAME TIME...BRINGING SCATTERED SNOW SHOWERS TO THE CWA...MAINLY NORTH OF THE METRO DETROIT AREA. ONCE THIS WAVE PASSES...GENERALLY DRY CONDITIONS ARE EXPECTED FRIDAY NIGHT INTO SATURDAY NIGHT. AS A LARGE HIGH PRESSURE SETTLES FROM THE MID MISSISSIPPI VALLEY TO THE TENNESSEE VALLEY. ACTUALLY...DRY WEATHER WILL MOST LIKELY HOLD INTO SUNDAY AS WELL A AREA OF LIGHT SNOW WITHING ISENTROPIC LIFT REGIME WILL MAINLY STAY TO THE NORTH OF THE AREA AS IT SHIFTS NORTHEAST THROUGH THE NORTHERN GREAT LAKES. THIS WILL LEAVE SOUTHEAST MICHIGAN IN A RELATIVELY MILD POSITION AS SOUTH FLOW INCREASES IN WARM AIR ADVECTION PATTERN. HIGH TEMPERATURES WILL PUSH 40...PARTICULARLY WHERE LITTLE/NO SNOW COVER EXISTS...AS OPPOSED TO THE UPPER 20S/LOWER 30S ON FRIDAY/SATURDAY. UNSETTLED WEATHER RETURNS SUNDAY NIGHT INTO MONDAY AS A STRONG WAVE ROTATES THROUGH THE NORTHERN LAKES REGION. THE ASSOCIATED UPPER TROUGH LOOKS TO BE AMPLIFIED ENOUGH TO TAP AT LEAST SOME GULF OF MEXICO MOISTURE...WHICH SHOULD ENHANCE AN AREA OF LIGHT SNOW OR MIX OF SNOW/RAIN IN ADVANCE OF THE TROUGH AXIS. AS THIS SYSTEM DIGS INTO THE GREAT LAKES...AND FORMS THEN FORMS INTO A RATHER LARGE UPPER LOW OVER THE NORTHEAST CONUS...SCATTERED SNOW SHOWERS WILL AGAIN BE PREVALENT OVER THE REGION...AS COLD CYCLONIC FLOW BECOMES ESTABLISHED THROUGH TUESDAY. THE WEATHER PATTERN MAY VERY WELL QUIET DOWN AGAIN LATE IN THE FORECAST AS A SHORTWAVE RIDGE SHIFTS OVER THE AREA IN RESPONSE TO THE NEXT LARGE NORTHERN STREAM SHORTWAVE...WHICH LOOKS TO DIG INTO THE NORTHERN PLAINS INITIALLY. THIS WILL BRING MILD SOUTHERLY WINDS BACK INTO THE AREA WITH HIGHS BACK TO AROUND 40 BY WEDNESDAY/THURSDAY NEXT WEEK. WOULD HAVE TO SAY CONFIDENCE IS...AT BEST...MARGINAL GIVEN THE VIGOR OF THE UPCOMING SHORTWAVES AND THE INFLUENCE THEY WILL LIKELY HAVE ON THE OVERALL EVOLUTION WITHIN THE UPPER LEVEL PATTERN. MARINE... THE PRESSURE GRADIENT OVER THE LAKES WILL TIGHTEN UP JUST A BIT TONIGHT AS THE TEMPERATURES OF THE LAND FALL THROUGH THE 20S...RESULTING IN A MODEST INCREASE IN WIND SPEEDS OVER LAKE HURON OVERNIGHT. THE INCREASE IN WINDS AND WAVES WILL BE SHORT LIVED...AS SURFACE RIDGE BUILDING INTO THE CENTRAL GREAT LAKES THROUGH SATURDAY MORNING ALLOWS FOR THE WINDS AND WAVES TO SUBSIDE AND BRING AN END TO THE SNOW SHOWERS. && .DTX WATCHES/WARNINGS/ADVISORIES... MI...LAKE EFFECT SNOW ADVISORY...MIZ049...UNTIL 7 AM FRIDAY. LAKE HURON... SMALL CRAFT ADVISORY...OUTER SAGINAW BAY...UNTIL 4 AM SATURDAY. SMALL CRAFT ADVISORY...INNER SAGINAW BAY...UNTIL 7 AM FRIDAY. SMALL CRAFT ADVISORY...NEARSHORE WATERS FROM PORT AUSTIN TO PORT HURON...UNTIL 10 AM SATURDAY. LAKE ST CLAIR... SMALL CRAFT ADVISORY...UNTIL 7 AM FRIDAY. MI WATERS OF LAKE ERIE... SMALL CRAFT ADVISORY...UNTIL 7 AM FRIDAY. && $$ AVIATION.....BT UPDATE.......BT SHORT TERM...SF LONG TERM....DG MARINE.......SF YOU CAN OBTAIN YOUR LATEST NATIONAL WEATHER SERVICE FORECASTS ONLINE AT WWW.WEATHER.GOV/DETROIT (ALL LOWER CASE). mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LUBBOCK TX 415 AM CST FRI NOV 21 2008 .SHORT TERM... RATHER BENIGN WEATHER FOR THE SHORT TERM. BOTH RUC AND NAM MODELS IN GOOD AGREEMENT THAT LOW CLOUDS NEAR THE NEW MEXICO BORDER WILL REMAIN THERE AND GRADUALLY DISSIPATE THIS MORNING. SHORTWAVE CURRENTLY SEEN ON WATER VAPOR...MOVING INTO WESTERN MONTANA TO CONTINUE MOVING EAST INTO SOUTH DAKOTA BY THIS EVENING THEN INTO IOWA BY SATURDAY MORNING. THIS FEATURE TO AID IN DEVELOPING A LEE SIDE LOW OVER SOUTHEAST COLORADO. THIS WITH SURFACE HIGH ALSO MOVING TO THE EAST WILL HAVE WINDS VEER AROUND TO THE SOUTH LATER THIS MORNING. WIND WILL ALSO PICK UP AND BECOME A BIT GUSTY AS SURFACE GRADIENT TIGHTENS. TEMPERATURES TO REMAIN ON THE COOL SIDE WITH WARMER TEMPERATURES OVER NORTHWEST ZONES WHERE WINDS EXPECTED TO BE MORE SOUTHWEST AND STRONGER. ALTHOUGH SKIES EXPECTED TO BE CLEAR AGAIN TONIGHT...WITH SOUTHERLY AND SLIGHTLY STRONGER WINDS ...LOWS TO BE SLIGHTLY WARMER THEN THIS MORNING. && .LONG TERM... MODERATING TREND WILL CONTINUE THROUGH THE WEEKEND AS FLAT RIDGE ALOFT PROMOTES SURFACE LOW PRESSURE OVER SOUTHERN HIGH PLAINS. DOWNSLOPE WARMING SHOULD INCREASE SUNDAY AS PRESSURE FALLS FURTHER IN RESPONSE TO THE NEXT CLIPPER-TYPE LOW DIVING SOUTHEAST THROUGH ALBERTA. THIS SYSTEM WILL CROSS THE GREAT LAKES MONDAY PULLING THE NEXT SURFACE COLD FRONT SOUTHWARD THR0UGH THE AREA PRIOR TO DAYBREAK MONDAY. CURRENT EXPECTATIONS CALL FOR MODEST SURFACE PRESSURE RISES EARLY MONDAY MORNING RESULTING IN BREEZY POST FRONTAL WINDS. TEMPERATURES MONDAY ALSO ANTICIPATED TO FALL ONLY MODESTLY. CONTINENTAL PATTERN IS THEN EXPECTED TO BEGIN AMPLIFICATION AS A SERIES OF PACIFIC LOWS DIG ONTO THE CALIFORNIA COAST SENDING HEIGHTS BACK UP ACROSS SOUTHERN HIGH PLAINS THROUGH MID-WEEK. PATTERN SHOULD REMAIN PROGRESSIVE INITIALLY WITH FLOW ALOFT BECOMING SOUTHWESTERLY ON WEDNESDAY. MOISTURE LEVELS SHOULD IMPROVE WITH CURRENT LONG RANGE GUIDANCE SUGGESTING ENOUGH MOISTENING FOR PRECIPITATION CONSIDERATION AS EARLY AS WEDNESDAY AS INITIAL DISTURBANCE SHEARS NORTHEAST ACROSS ROCKIES FROM THE CALIFORNIA COAST. TO US THIS WAVE LOOKS TOO OPEN WHILE ATMOSPHERE LIKELY WILL NEED MORE MOISTURE DEEPENING AS WELL. ANOTHER STRONGER THOUGH STILL SOMEWHAT OPEN WAVE IS EXPECTED TO PROGRESS FROM THE WEST COAST OVER SOUTHERN PLAINS THANKSGIVING DAY. THIS WAVE HAS SHOWN GOOD CONTINUITY ON ENSEMBLE RUNS FOR THE PAST WEEK...AND AT THIS POINT HAS CREDIBILITY ENOUGH TO WARRANT INITIAL LOW END SHOWER CHANCES AS MOISTURE EXPECTED TO BE ADEQUATE AS WELL. TEMPERATURE PROFILE CLEARLY FAVORS LIQUID THIS FAR OUT AND ALSO SUGGESTS PRECIPITATION MAY BE CONVECTIVE. THIS WAVE SHOULD LIFT TO THE EAST-NORTHEAST THURSDAY NIGHT OR EARLY FRIDAY... WITH MODEL TIMING ISSUES FACTORING INTO UNCERTAINTY. MCQUEEN && .PRELIMINARY POINT TEMPS/POPS... FRIONA 46 26 62 31 69 / 0 0 0 0 0 TULIA 45 26 61 31 67 / 0 0 0 0 0 PLAINVIEW 45 27 61 32 69 / 0 0 0 0 0 LEVELLAND 45 28 62 32 70 / 0 0 0 0 0 LUBBOCK 46 29 61 35 71 / 0 0 0 0 0 DENVER CITY 46 30 64 35 72 / 0 0 0 0 0 BROWNFIELD 47 30 63 33 72 / 0 0 0 0 0 CHILDRESS 48 29 59 35 69 / 0 0 0 0 0 SPUR 48 31 62 35 70 / 0 0 0 0 0 ASPERMONT 50 31 63 40 71 / 0 0 0 0 0 && .LUB WATCHES/WARNINGS/ADVISORIES... NONE. && $$ 08/05 tx AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE PUEBLO CO 734 AM MST FRI NOV 21 2008 .UPDATE... VISIBILITIES ARE STARTING TO IMPROVE ACROSS NORTHERN EL PASO COUNTY...SO WILL LET THE DENSE FOG ADVISORY EXPIRE. THE STRATUS SHOULD BEGIN TO BURN OFF BY MIDDLE TO LATE MORNING ACROSS EL PASO...PUEBLO...AND THE SAN LUIS VALLEY...HOPEFULLY. METZE && .PREV DISCUSSION... /ISSUED 340 AM MST FRI NOV 21 2008/ SHORT TERM... (TODAY AND TONIGHT) ..SOME EARLY MORNING DENSE FOG NORTHERN EL PASO COUNTY... ..A LITTLE WARMER TEMPERATURES AND SUNSHINE SOUTHEAST CO TODAY... CURRENTLY...WEST-NORTHWESTERLY FLOW INCREASING ALOFT OVER THE CENTRAL ROCKIES. HIGH TERRAIN AWOS MOUNTAIN PASS SENSORS REPORTING 15-29KTS WITH GUSTS 30-35KTS. PIKES PEAK IS SUSTAINED 40 MPH WITH A PEAK WIND OF 57 MPH. IN RESPONSE TO THE MIDLEVEL WARM AIR ADVECTION...LEE SIDE TROUGH BEGINNING TO DEVELOP ACROSS EASTERN CO WITH BRISK SOUTHERLY WINDS ACROSS MUCH OF THE FAR EASTERN CO PLAINS AND THE SOUTHERN PALMER DIVIDE. PUEBLO-LA JUNTA HAS WEAK EASTERLY FLOW IN THE LOWER AR RIVER VALLEY. IFR-MVFR STRATUS BREAKING UP ACROSS PORTIONS OF SOUTHEASTERN CO DUE TO RELATIVELY DRIER AIR ALOFT ENTRAINING INTO THE LOW LEVEL MOISTURE. HOWEVER...AS USUAL...STRATUS AND FOG HOLDING TIGHT ACROSS EL PASO COUNTY WITH THE SOUTHERLY MOIST OROGRAPHIC FLOW. VERY DENSE FREEZING FOG ACROSS NORTHERN EL PASO PER LIVE WEB CAMS SINCE WE CAME INTO THE OFFICE AT MIDNIGHT. FOUR OUT OF THE FIVE NORTHERN EL PASO COUNTY I-25 CORRIDOR WEB CAMS HAD ZERO VISIBILITIES. ALREADY ISSUED THE DENSE FOG ADVISORY AROUND 1245 AM...SO THAT STILL LOOKS ON TARGET. PATCHY DENSE FOG...ALSO...NOTED IN DOWNTOWN COLORADO SPRINGS NOW. TODAY...RATHER VIGOROUS MIDLEVEL SHORTWAVE TROUGH AND ASSOCIATED JET STREAK TO PUSH JUST NORTH OF CO TODAY. A LITTLE STRONGER MIDLEVEL WINDS...ALONG WITH DRIER AIR ALOFT...AS THIS SYSTEM BRUSHES CO. MODEL SOUNDINGS SUGGEST THE DENSE FREEZING FOG/STRATUS SHOULD BREAK UP ACROSS EL PASO COUNTY BETWEEN 500 AM AND 800 AM THIS MORNING...SO WILL MAINTAIN THE DENSE FOG ADVISORY DUE TO MORNING RUSH HOUR TO START BETWEEN 400-500 AM. AFTER THE STRATUS DISSIPATES THIS MORNING...JUST LOOKING FOR MAINLY HIGH CLOUDS AND A POSSIBLE SCT-BKN THIN CI/CS MOUNTAIN WAVE CLOUD ALONG THE FRONT RANGE LATER THIS MORNING AND AFTERNOON. TEMPERATURES WILL BE TRICKY AND MOST LOCATIONS SHOULD BE WARMER THAN YESTERDAY GIVEN NORTHWEST FLOW CHINOOK. THE BIGGEST C51ENGE WILL BE FROM PUEBLO TO LA JUNTA IN THE LOWER AR RIVER VALLEY. THE HIGH RESOLUTION MODEL DATA...RUC AND NAM-WRF...SUGGEST SURFACE WINDS COULD STAY EASTERLY MUCH OF THE DAY. THIS COULD LIMIT THE POTENTIAL WARMING IN THESE AREAS GIVEN THE LIGHTER WINDS...LOWER SUN ANGLE...AND ANY HIGH CLOUDS...HOWEVER... 700MB WINDS ARE PROGGED TO BE 30-40KTS BY THE RUC YET THE NAM-WRF ONLY HAS 15-20KTS. IF THE WINDS DON`T PICK UP THEN HIGHS 45-50F AT PUEBLO...IF THEY PICK UP THEN HIGHS 55-60F. TONIGHT...NORTHWEST FLOW CONTINUES AND WEAKENS. WITH A NEARLY CLEAR SKY...STRONG RADIATIONAL COOLING WILL OCCUR IN VALLEYS WITH THE BANANA-BELT WARMER TEMPERATURES LIKELY GENERALLY ALONG I-25 CORRIDOR AND WESTWARDS TOWARDS THE MOUNTAINS FROM 6K-9K FT MSL...AND NEAR THE MOUNTAINS IN THE UPPER AR RIVER VALLEY AND SAN LUIS VALLEY. 17 LONG TERM... (SATURDAY THROUGH THANKSGIVING) ..DRY PATTERN TO CONTINUE THROUGH EARLY NEXT WEEK... ..UNSETTLED WEATHER TO RETURN BY THANKSGIVING... THIS WEEKEND AND EARLY NEXT WEEK CONTINUE TO LOOK DRY WITH ABOVE AVERAGE TEMPERATURES FOR MOST OF THE CWA. A SHORT WAVE RIDGE WILL MOVE THROUGH ON SATURDAY AND TEMPERATURES SHOULD RISE TO NEAR 60 DEGREES OVR THE PLAINS IN THE AFTERNOON. OVERNIGHT TEMPS WILL BE IN THE 20S AS SKIES REMAIN GENERALLY CLEAR. WILL SEE THE USUAL BELT OF HIGHER TEMPS OVER THE ERN FOOTHILLS AND HIGHER TERRAIN. A SHORTWAVE WILL MOVE THRU THE DAKOTAS AND UPPER MISS VALLEY ON SUN...BUT MODELS ARE QUITE CONSISTENT IN SHOWING LITTLE SENSIBLE IMPACT FROM THIS PARTICULAR SYSTEM. HAVE LEFT SLIGHTLY COOLER WX INTACT FOR THE NERN ZONES. SKIES WILL CONTINUE TO BE MOSTLY CLEAR THRU MON AS THE UPPER RIDGE REBUILDS AND THE ATMOS REMAINS VERY DRY. ALL SIGNS CONTINUE TO POINT TO A CHANGE IN THIS PERSISTENT PATTERN BY WED OF NEXT WEEK. ENSEMBLE SPAGHETTI PLOTS ARE IN REMARKABLY GOOD AGREEMENT THRU ABOUT 200 H. H7 ZERO LINE WILL MOVE THRU SERN CO ON WED...AND THE NEXT 3-4 DAYS PROMISE TO BE COOL AND UNSETTLED. A LEAD SHORTWAVE TROUGH WILL MOVE INTO THE SWRN MTS LATE WED OR THU...AND HOPEFULLY THIS WILL BRING SOME NEEDED MOISTURE TO THE DVD. COULD EVEN SEE SOME PRECIP OVER THE PLAINS BY THE END OF THE WEEK. THE SCENARIO BECOMES MORE COMPLEX BY NEXT WEEKEND AS THE MAIN GLOBAL MODELS HAVE BEEN PERSISTENT IN AMPLIFYING THE W COAST TROUGH AND CUTTING OFF AN UPPER LOW OVR SRN CA OVR THE DESERT SW...POSSIBLY EVEN NRN MEXICO/BAJA. THIS COULD RETURN THE AREA TO A STAGNANT WX PATTERN BY THE LATTER HALF OF THE WEEKEND. WILL HAVE TO WAIT TO SEE HOW THIS DEVELOPS OVR THE NEXT FEW DAYS. 44 AVIATION... PER SHORT TERM DISCUSSION...LIFR CIGS AND IFR-LIFR VIS SHOULD DISSIPATE AROUND THE KCOS TERMINAL BETWEEN 13Z-15Z/21. OTHERWISE...VFR CLEAR BELOW 12K SHOULD BE THE RULE FOR KCOS... KPUB...AND KALS TERMINAL POINTS REST OF TODAY AND TONIGHT. 17 && .PUB WATCHES/WARNINGS/ADVISORIES... NONE. && $$ 17/17 co AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LINCOLN IL 1004 AM CST FRI NOV 21 2008 .DISCUSSION... ISSUED 1000 AM CST FRI NOV 21 2008 FORECAST LOOKS ON TRACK AGAIN TODAY AND ONLY MINOR UPDATES TO THE HOURLY GRIDS. SUNNY SKIES WITH WNW WINDS OF 5 TO 15 MPH. HIGHS IN THE LOWER 30S OVER CENTRAL IL AND MIDDLE 30S IN SOUTHEAST IL. COLDEST MORNING SO FAR THIS FALL ACROSS MUCH OF CENTRAL IL WITH LOWS IN THE MID TO UPPER TEENS. LOWS WERE IN THE LOWER 20S SE OF I-70. ALTONA...PRINCEVILLE AND MINONK WERE THE COLD SPOTS AT 11F AND THATS WITHOUT A SNOW COVER. SUNNY SKIES PREVAILED ACROSS IL THIS MORNING THANKS TO STRONG 1040 MB CANADIAN HIGH PRESSURE OVER MO AND EASTERN OK AND RIDGING NORTHWARD ACROSS MN. CHILLY TEMPERATURES WERE IN THE LOWER 20S OVER CENTRAL IL AND MID 20S IN SE IL WITH BLOOMINGTON STILL AT 19F. LIGHTER NW WINDS OF 6 TO 13 MPH PREVAILED THIS MORNING. ALOFT IL REMAINS DEEPLY ENTRENCHED IN A QUIET NW UPPER LEVEL FLOW WITH STRONG UPER LEVEL TROF OVER EASTERN NORTH AMERICA AND UPPER LEVEL RIDGE OVER THE CANADIAN AND U.S. PLAINS. DECENT UPPER LEVEL TROF WAS OVER MT. 12Z RUC...NAM AND SREF MODELS WEAKEN STRONG CANADIAN HIGH PRESSURE A BIT TO 1036 MB AS IT DRIFTS EAST OVER THE MID MS VALLEY BY 00Z/6 PM TODAY. THIS WILL ENSURE SUNNY SKIES TODAY AS NW WINDS OF 8 TO 15 MPH BECOMING LIGHT WEST BY SUNSET. VERY COLD 850 MB TEMPS OF -11 TO -14C AT DAWN ONLY ELEVATE TO BETWEEN -5 TO -9C BY SUNSET. SO DESPITE THE SUNSHINE...WELL BELOW NORMAL HIGHS AGAIN TODAY IN THE LOWER 30S CENTRAL IL AND MID 30S SE IL. NORMAL HIGHS TODAY ARE IN THE UPPER 40S CENTRAL IL AND LOWER 50S SE IL. STRONG SHORT WAVE TROF OVER MT TO ZIP ESE TOWARD NW IA BY DAWN SAT FIRST SPREADING CIRRUS AND THEN MID LEVEL CLOUDS EAST ACROSS CENTRAL IL DURING TONIGHT. HUETTL && .AVIATION... ISSUED 538 AM CST FRI NOV 21 2008...FOR THE 12Z TAFS CLEAR SKIES AND LIGHT NW WINDS WILL PREVAIL TODAY UNDER HIGH PRESSURE. VFR CONDITIONS WILL CONTINUE THROUGH TOMORROW MORNING. SOME AC CLOUDS ARE EXPECTED LATE TONIGHT...BUT ONLY A 10K FT DECK SHOULD ARRIVE IN PIA BY 12Z...WITH HIGHER CLOUDS FOR THE OTHER TAF SITES. THE SURFACE RIDGE AXIS WILL SHIFT EAST OF ILLINOIS TONIGHT...CAUSING WINDS TO BECOME SOUTHERLY AFTER MIDNIGHT AT ALL TAF SITES. SHIMON && .PREV DISCUSSION... ISSUED 235 AM CST FRI NOV 21 2008 SKIES HAVE CLEARED BEHIND THE LATEST SHORTWAVE TO PASS THROUGH THE AREA. DRIER AIR HAS BEEN SPREADING IN FROM THE NORTHWEST...WITH DEWPOINTS IN THE SINGLE DIGITS NORTHWEST OF I-55. LOOKING FOR A QUIET AND RATHER COLD DAY AHEAD OF WARMER CONDITIONS FOR THE WEEKEND. MAIN FORECAST ISSUES TODAY INCLUDE FLURRIES POTENTIAL ON SATURDAY AND THE EFFECTS OF A STORM SYSTEM SUNDAY NIGHT AND MONDAY. SHORT TERM...TODAY THROUGH SUNDAY... SURFACE HIGH PRESSURE RIDGE TO MOVE EAST ACROSS THE MID- MISSISSIPPI VALLEY. MOSTLY CLEAR SKIES AND COLD CONDITIONS WILL BE THE RESULT. WINDS WILL DECREASE AS THE HIGH MOVES OVER THE AREA...AND WITH THE VERY DRY AIR IN PLACE...TEMPERATURES SHOULD FALL QUICKLY THIS EVENING. EXPECTING NEARLY STEADY TEMPERATURES OVERNIGHT PRIMARILY OVER THE WESTERN HALF OF THE FORECAST AREA...AS CLOUDS MOVE IN FROM THE NORTHWEST AND WINDS TURN SOUTHERLY. THE CLOUDS WILL BE ASSOCIATED WITH A SHORTWAVE...THAT WAS ANALYZED THIS EVENING OVER IDAHO AND WESTERN MONTANA. MODELS ARE IN GOOD AGREEMENT WITH THIS BECOMING A SMALL CLOSED UPPER LOW AS IT ZIPS SOUTHEAST INTO THE NORTHERN PLAINS THIS EVENING...BEFORE WEAKENING AS IT MOVES INTO ILLINOIS ON SATURDAY. NOT MUCH OF A SURFACE REFLECTION INDICATED...AND DRY AIR WILL REMAIN IN PLACE. DESPITE THAT...THERE SHOULD BE ENOUGH UPPER LEVEL ENERGY TO SQUEEZE OUT A FEW FLURRIES ON SATURDAY...PRIMARILY ACROSS THE NORTHWEST HALF OF THE CWA. ONCE THIS SYSTEM PASSES...WARM AIR ADVECTION WILL INCREASE AND ALLOW TEMPERATURES TO REACH THE LOWER 40S ON SATURDAY AND APPROACH 50 DEGREES ON SUNDAY. LONG TERM...SUNDAY NIGHT THROUGH THURSDAY... DEEPENING UPPER LOW WILL MOVE SOUTHEAST INTO THE GREAT LAKES REGION ON MONDAY. ASSOCIATED SURFACE COLD FRONT PROGGED TO MOVE ACROSS ILLINOIS SUNDAY NIGHT. BEST PRECIPITATION CHANCES WILL BE ACROSS THE SOUTHEAST CWA WHERE MORE GULF MOISTURE WILL BE AVAILABLE BEFORE THE FRONT ARRIVES...ALTHOUGH LOW CHANCES ARE IN THE FORECAST AS FAR NORTHWEST AS I-55. MODEL SOUNDINGS SHOW RAIN TO BE THE PRIMARY ISSUE...ALTHOUGH AREAS NORTHWEST OF I-55 MAY SEE THE RAIN CHANGE TO SNOW LATE SUNDAY NIGHT IF PRECIPITATION DOES MANAGE TO FORM THAT FAR NORTHWEST. BRISK WEST/NORTHWEST WINDS BEHIND THE FRONT ON MONDAY WILL MAKE THINGS FEEL COLDER THAN THE 40S CURRENTLY FORECAST FOR HIGHS. LONGER RANGE MODELS ARE STILL DIVERGING BY THE MIDDLE OF THE WEEK WITH RESOLUTION OF THE MOVEMENT OF THE AFOREMENTIONED UPPER LOW...AND ITS AFFECTS ON THE PROGRESSION OF A DIGGING TROUGH ACROSS THE WESTERN U.S. NO CHANGES WERE MADE PAST TUESDAY MORNING AT THIS TIME. GEELHART && .ILX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ il AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE MARQUETTE MI 1050 AM EST FRI NOV 21 2008 UPDATED FOR HEADLINE SECTION .DISCUSSION... ISSUED AT 500 AM EST SEVERAL HEADLINES EXPIRE AT 7 AM EST THIS MORNING. THIS SEEMS REASONABLE FOR THE WESTERN COUNTIES GIVEN THE NORTHWESTERLY FLOW...AND GENERALLY DRY AIR UPSTREAM. CONVERGENCE EAST INCREASES TODAY...AS HIGH PRESSURE ROLLS TOWARDS WESTERN LAKE SUPERIOR. THE MOST DOMINATE BAND ON THE RADAR LOOKS TO STRETCH ALMOST PARALLEL TO MARQUETTE COUNTY...CROSSING INTO WESTERN ALGER COUNTY...AND OVER EBEN JUNCTION AND JUST EAST OF TRENARY. AN EASTERN PUSH TO THESE BANDS WILL CONTINUE TODAY. INCORPORATED BS ON LAND WHERE WIND GUSTS WHERE GREATER THAN 22KT...WHICH ENDED UP BEING MAINLY THIS MORNING NEAR LAKE SUPERIOR. ONE OF THE MAIN QUESTIONS IS WHEN LAKE EFFECT SNOW SHOWERS WILL END OVER THE CWA. OUT WEST...FOR GOGEBIC COUNTY THIS COULD BE AS EARLY AS 12Z THIS MORNING AS WNW WINDS BECOME MORE WESTERLY SIGNIFICANTLY LESSENING THE FETCH OVER LAKE SUPERIOR. THE RUC IS QUICKEST TO ALLOW FOR A WESTERLY WIND OVER GOGEBIC AND SOUTHERN ONTONAGON COUNTIES. HOWEVER...WESTERLY FLOW TAKES A BIT LONGER TO GET TO ONTONAGON COUNTY...WITH MODELS SHOWING 00Z AS THE CUT OFF POINT. ADDING TO THIS WILL BE THE NEXT BROAD SHORTWAVE MOVING MAINLY EST OF THE CWA LATE THIS AFTERNOON/EARLY THIS EVENING...ENHANCING SNOWFALL SLIGHTLY OVER THE EASTERN UPPER PENINSULA. TEMPERATURE WISE...THERE IS VERY LITTLE DIFFERENCE IN GUIDANCE VALUES...SO WILL GO WITH THE CONSENSUS FOR TODAY. A BLEND SEEMS REASONABLE FOR TONIGHT...AS THE NAM/MET DROPS TEMPERATURES TO 0F AND THE GFS/MAV DISPLAYS SINGLE DIGITS. OTHERWISE FOR THE WEEKEND...WILL ADJUST AFTERNOON HIGH TEMPERATURES UP A DEGREE OR TWO. HAVE SECOND GUESSED THIS DUE TO THE INFLUENCE OF THE SNOWPACK...AND IF THIS IS BEING HANDLED BY THE MODELS QUITE YET. HAVE LOW CONFIDENCE IN THE POTENTIAL FOR SNOW OR FREEZING DRIZZLE SATURDAY NIGHT INTO SUNDAY...ALTHOUGH IT IS ONLY 20 PERCENT. IF WE DO GET PRECIPITATION A MIX SEEMS REALISTIC...AS 850MB TEMPERATURES RISE TO THE -5 OR -6C OFF THE NAM AND GFS. THE 12Z/20 ECMWF WARMS TO -2 TO -3C OVER THE WESTERN PORTIONS OF THE CWA BY THE SAME TIME...12Z SUNDAY. INCREASED SKY COVER MONDAY AFTERNOON THOUGH TUESDAY...WITH NORTHERLY FLOW OFF LAKE SUPERIOR AND 850MB TEMPERATURES HOVERING NEAR -7 TO -10C. BY TUESDAY AFTERNOON WARM AIR WILL BE ENCROACHING ALOFT...RISING 850MB TEMPERATURES TO -6C OR WARMER...EFFECTIVELY MINIMIZING LAKE ENHANCED SNOW AND TO A LESSER EXTENT CLOUD COVER. && .AVIATION (FOR THE 12Z TAF ISSUANCE)... AS HIGH PRES RIDGE MOVES E...REACHING UPPER MI TONIGHT...EXPECT A GRADUAL BACKING OF WINDS OVER THE NEXT 24 HRS. WITH CONTINUED COLD FLOW ACROSS LAKE SUPERIOR TO KCMX...-SHSN WILL CONTINUE AT KCMX THRU THIS FCST PERIOD WITH PREVAILING VIS AND CIGS PROBABLY IN THE MVFR RANGE THOUGH THERE WILL CERTAINLY BE PERIODS OF VFR VIS. MAY SEE A PERIOD OF IFR VIS LATE TONIGHT AS LAND BREEZE ENHANCED BACKING OF WINDS OVER WRN LAKE SUPERIOR STRENGTHEN LOW-LEVEL CONVERGENCE... SUPPORTING SOME HEAVIER -SHSN. AT KSAW...BACKING WINDS WILL BRING AN END TO LINGERING -SHSN THIS MORNING. GRADUAL LOWERING OF INVERSION SHOULD RESULT IN PREVAILING MVFR CIGS...BUT CLOUDS SHOULD CLEAR OUT LATE TONIGHT AS HIGH PRES RIDGE AXIS ARRIVES. && .MARINE (FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)... FREQUENT GALE FORCE GUSTS OVER ERN LAKE SUPERIOR WILL END BEFORE SUNRISE AS PRES GRADIENT GRADUALLY RELAXES WITH HIGH PRES RIDGE EDGING TOWARD THE UPPER LAKES. THE RIDGE WILL PASS ACROSS LAKE SUPERIOR TONIGHT AND SAT MORNING...PROVIDING A PERIOD OF LIGHT WINDS GENERALLY UNDER 15 KNOTS. NEXT ROUND OF STRONG WINDS (AROUND 30KT) WILL DEVELOP MON THRU EARLY TUE MORNING IN THE WAKE OF LOW PRES DIVING SE THRU THE UPPER GREAT LAKES. STRONGEST WINDS WILL OCCUR OVER CNTRL AND ERN LAKE SUPERIOR. NOT OUT OF THE QUESTION THAT GALES COULD DEVELOP. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... LAKE EFFECT SNOW WARNING UNTIL 10 PM EST THIS EVENING FOR MIZ006-007-085. LAKE EFFECT SNOW WARNING UNTIL 1 PM EST THIS AFTERNOON FOR MIZ014. && $$ DISCUSSION...KF AVIATION...ROLFSON MARINE...ROLFSON mi AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE MARQUETTE MI 640 AM EST FRI NOV 21 2008 UPDATED AVIATION DISCUSSION FOR 12Z TAF ISSUANCE .DISCUSSION... ISSUED AT 500 AM EST SEVERAL HEADLINES EXPIRE AT 7 AM EST THIS MORNING. THIS SEEMS REASONABLE FOR THE WESTERN COUNTIES GIVEN THE NORTHWESTERLY FLOW...AND GENERALLY DRY AIR UPSTREAM. CONVERGENCE EAST INCREASES TODAY...AS HIGH PRESSURE ROLLS TOWARDS WESTERN LAKE SUPERIOR. THE MOST DOMINATE BAND ON THE RADAR LOOKS TO STRETCH ALMOST PARALLEL TO MARQUETTE COUNTY...CROSSING INTO WESTERN ALGER COUNTY...AND OVER EBEN JUNCTION AND JUST EAST OF TRENARY. AN EASTERN PUSH TO THESE BANDS WILL CONTINUE TODAY. INCORPORATED BS ON LAND WHERE WIND GUSTS WHERE GREATER THAN 22KT...WHICH ENDED UP BEING MAINLY THIS MORNING NEAR LAKE SUPERIOR. ONE OF THE MAIN QUESTIONS IS WHEN LAKE EFFECT SNOW SHOWERS WILL END OVER THE CWA. OUT WEST...FOR GOGEBIC COUNTY THIS COULD BE AS EARLY AS 12Z THIS MORNING AS WNW WINDS BECOME MORE WESTERLY SIGNIFICANTLY LESSENING THE FETCH OVER LAKE SUPERIOR. THE RUC IS QUICKEST TO ALLOW FOR A WESTERLY WIND OVER GOGEBIC AND SOUTHERN ONTONAGON COUNTIES. HOWEVER...WESTERLY FLOW TAKES A BIT LONGER TO GET TO ONTONAGON COUNTY...WITH MODELS SHOWING 00Z AS THE CUT OFF POINT. ADDING TO THIS WILL BE THE NEXT BROAD SHORTWAVE MOVING MAINLY EST OF THE CWA LATE THIS AFTERNOON/EARLY THIS EVENING...ENHANCING SNOWFALL SLIGHTLY OVER THE EASTERN UPPER PENINSULA. TEMPERATURE WISE...THERE IS VERY LITTLE DIFFERENCE IN GUIDANCE VALUES...SO WILL GO WITH THE CONSENSUS FOR TODAY. A BLEND SEEMS REASONABLE FOR TONIGHT...AS THE NAM/MET DROPS TEMPERATURES TO 0F AND THE GFS/MAV DISPLAYS SINGLE DIGITS. OTHERWISE FOR THE WEEKEND...WILL ADJUST AFTERNOON HIGH TEMPERATURES UP A DEGREE OR TWO. HAVE SECOND GUESSED THIS DUE TO THE INFLUENCE OF THE SNOWPACK...AND IF THIS IS BEING HANDLED BY THE MODELS QUITE YET. HAVE LOW CONFIDENCE IN THE POTENTIAL FOR SNOW OR FREEZING DRIZZLE SATURDAY NIGHT INTO SUNDAY...ALTHOUGH IT IS ONLY 20 PERCENT. IF WE DO GET PRECIPITATION A MIX SEEMS REALISTIC...AS 850MB TEMPERATURES RISE TO THE -5 OR -6C OFF THE NAM AND GFS. THE 12Z/20 ECMWF WARMS TO -2 TO -3C OVER THE WESTERN PORTIONS OF THE CWA BY THE SAME TIME...12Z SUNDAY. INCREASED SKY COVER MONDAY AFTERNOON THOUGH TUESDAY...WITH NORTHERLY FLOW OFF LAKE SUPERIOR AND 850MB TEMPERATURES HOVERING NEAR -7 TO -10C. BY TUESDAY AFTERNOON WARM AIR WILL BE ENCROACHING ALOFT...RISING 850MB TEMPERATURES TO -6C OR WARMER...EFFECTIVELY MINIMIZING LAKE ENHANCED SNOW AND TO A LESSER EXTENT CLOUD COVER. && .AVIATION (FOR THE 12Z TAF ISSUANCE)... AS HIGH PRES RIDGE MOVES E...REACHING UPPER MI TONIGHT...EXPECT A GRADUAL BACKING OF WINDS OVER THE NEXT 24 HRS. WITH CONTINUED COLD FLOW ACROSS LAKE SUPERIOR TO KCMX...-SHSN WILL CONTINUE AT KCMX THRU THIS FCST PERIOD WITH PREVAILING VIS AND CIGS PROBABLY IN THE MVFR RANGE THOUGH THERE WILL CERTAINLY BE PERIODS OF VFR VIS. MAY SEE A PERIOD OF IFR VIS LATE TONIGHT AS LAND BREEZE ENHANCED BACKING OF WINDS OVER WRN LAKE SUPERIOR STRENGTHEN LOW-LEVEL CONVERGENCE... SUPPORTING SOME HEAVIER -SHSN. AT KSAW...BACKING WINDS WILL BRING AN END TO LINGERING -SHSN THIS MORNING. GRADUAL LOWERING OF INVERSION SHOULD RESULT IN PREVAILING MVFR CIGS...BUT CLOUDS SHOULD CLEAR OUT LATE TONIGHT AS HIGH PRES RIDGE AXIS ARRIVES. && .MARINE (FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)... FREQUENT GALE FORCE GUSTS OVER ERN LAKE SUPERIOR WILL END BEFORE SUNRISE AS PRES GRADIENT GRADUALLY RELAXES WITH HIGH PRES RIDGE EDGING TOWARD THE UPPER LAKES. THE RIDGE WILL PASS ACROSS LAKE SUPERIOR TONIGHT AND SAT MORNING...PROVIDING A PERIOD OF LIGHT WINDS GENERALLY UNDER 15 KNOTS. NEXT ROUND OF STRONG WINDS (AROUND 30KT) WILL DEVELOP MON THRU EARLY TUE MORNING IN THE WAKE OF LOW PRES DIVING SE THRU THE UPPER GREAT LAKES. STRONGEST WINDS WILL OCCUR OVER CNTRL AND ERN LAKE SUPERIOR. NOT OUT OF THE QUESTION THAT GALES COULD DEVELOP. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... LAKE EFFECT SNOW ADVISORY UNTIL 7 AM EST /6 AM CST/ THIS MORNING FOR MIZ001>004-009-084. LAKE EFFECT SNOW WARNING UNTIL 10 AM EST THIS MORNING FOR MIZ005. LAKE EFFECT SNOW WARNING UNTIL 1 PM EST THIS AFTERNOON FOR MIZ013-014. LAKE EFFECT SNOW WARNING UNTIL 10 PM EST THIS EVENING FOR MIZ006- 007-085. LAKE SUPERIOR... GALE WARNING UNTIL 7 AM EST THIS MORNING FOR LSZ249>251-266-267. LAKE MICHIGAN... GALE WARNING UNTIL 7 AM EST THIS MORNING FOR LMZ221-250. && $$ DISCUSSION...KF AVIATION...ROLFSON MARINE...ROLFSON mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 500 AM EST FRI NOV 21 2008 .DISCUSSION... SEVERAL HEADLINES EXPIRE AT 7 AM EST THIS MORNING. THIS SEEMS REASONABLE FOR THE WESTERN COUNTIES GIVEN THE NORTHWESTERLY FLOW...AND GENERALLY DRY AIR UPSTREAM. CONVERGENCE EAST INCREASES TODAY...AS HIGH PRESSURE ROLLS TOWARDS WESTERN LAKE SUPERIOR. THE MOST DOMINATE BAND ON THE RADAR LOOKS TO STRETCH ALMOST PARALLEL TO MARQUETTE COUNTY...CROSSING INTO WESTERN ALGER COUNTY...AND OVER EBEN JUNCTION AND JUST EAST OF TRENARY. AN EASTERN PUSH TO THESE BANDS WILL CONTINUE TODAY. INCORPORATED BS ON LAND WHERE WIND GUSTS WHERE GREATER THAN 22KT...WHICH ENDED UP BEING MAINLY THIS MORNING NEAR LAKE SUPERIOR. ONE OF THE MAIN QUESTIONS IS WHEN LAKE EFFECT SNOW SHOWERS WILL END OVER THE CWA. OUT WEST...FOR GOGEBIC COUNTY THIS COULD BE AS EARLY AS 12Z THIS MORNING AS WNW WINDS BECOME MORE WESTERLY SIGNIFICANTLY LESSENING THE FETCH OVER LAKE SUPERIOR. THE RUC IS QUICKEST TO ALLOW FOR A WESTERLY WIND OVER GOGEBIC AND SOUTHERN ONTONAGON COUNTIES. HOWEVER...WESTERLY FLOW TAKES A BIT LONGER TO GET TO ONTONAGON COUNTY...WITH MODELS SHOWING 00Z AS THE CUT OFF POINT. ADDING TO THIS WILL BE THE NEXT BROAD SHORTWAVE MOVING MAINLY EST OF THE CWA LATE THIS AFTERNOON/EARLY THIS EVENING...ENHANCING SNOWFALL SLIGHTLY OVER THE EASTERN UPPER PENINSULA. TEMPERATURE WISE...THERE IS VERY LITTLE DIFFERENCE IN GUIDANCE VALUES...SO WILL GO WITH THE CONSENSUS FOR TODAY. A BLEND SEEMS REASONABLE FOR TONIGHT...AS THE NAM/MET DROPS TEMPERATURES TO 0F AND THE GFS/MAV DISPLAYS SINGLE DIGITS. OTHERWISE FOR THE WEEKEND...WILL ADJUST AFTERNOON HIGH TEMPERATURES UP A DEGREE OR TWO. HAVE SECOND GUESSED THIS DUE TO THE INFLUENCE OF THE SNOWPACK...AND IF THIS IS BEING HANDLED BY THE MODELS QUITE YET. HAVE LOW CONFIDENCE IN THE POTENTIAL FOR SNOW OR FREEZING DRIZZLE SATURDAY NIGHT INTO SUNDAY...ALTHOUGH IT IS ONLY 20 PERCENT. IF WE DO GET PRECIPITATION A MIX SEEMS REALISTIC...AS 850MB TEMPERATURES RISE TO THE -5 OR -6C OFF THE NAM AND GFS. THE 12Z/20 ECMWF WARMS TO -2 TO -3C OVER THE WESTERN PORTIONS OF THE CWA BY THE SAME TIME...12Z SUNDAY. INCREASED SKY COVER MONDAY AFTERNOON THOUGH TUESDAY...WITH NORTHERLY FLOW OFF LAKE SUPERIOR AND 850MB TEMPERATURES HOVERING NEAR -7 TO -10C. BY TUESDAY AFTERNOON WARM AIR WILL BE ENCROACHING ALOFT...RISING 850MB TEMPERATURES TO -6C OR WARMER...EFFECTIVELY MINIMIZING LAKE ENHANCED SNOW AND TO A LESSER EXTENT CLOUD COVER. && .AVIATION (FOR THE 06Z TAF ISSUANCE)... WINDS BACKING TO THE NORTHWEST WILL ALLOW LK EFFECT SNOW SHOWERS TO MAINLY IMPACT CMX OVR THE NEXT 24 HRS. IN GENERAL...EXPECT MVFR CIGS AND VSBY IN THE SNOW SHOWERS. ISOLD HEAVIER BANDS OF SNOW SHIFTING ACROSS MARQUETTE COUNTY MAY IMPACT SAW THE REST OF TONIGHT WITH BRIEF IFR VSBY/CIGS...BUT OTHERWISE SNOW SHOWERS SHOULD END AT SAW BY FRIDAY MORNING AS NW WINDS ARE UNFAVORABLE FOR SNOW SHOWERS THERE. HOWEVER AS INVERSION LOWERS ON FRIDAY AND LOW LEVEL MOISTURE PERSISTS...THERE COULD BE STILL BE CIGS IN THE MVFR CATEGORY AT SAW. && .MARINE (FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)... FREQUENT GALE FORCE GUSTS OVER ERN LAKE SUPERIOR WILL END BEFORE SUNRISE AS PRES GRADIENT GRADUALLY RELAXES WITH HIGH PRES RIDGE EDGING TOWARD THE UPPER LAKES. THE RIDGE WILL PASS ACROSS LAKE SUPERIOR TONIGHT AND SAT MORNING...PROVIDING A PERIOD OF LIGHT WINDS GENERALLY UNDER 15 KNOTS. NEXT ROUND OF STRONG WINDS (AROUND 30KT) WILL DEVELOP MON THRU EARLY TUE MORNING IN THE WAKE OF LOW PRES DIVING SE THRU THE UPPER GREAT LAKES. STRONGEST WINDS WILL OCCUR OVER CNTRL AND ERN LAKE SUPERIOR. NOT OUT OF THE QUESTION THAT GALES COULD DEVELOP. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... LAKE EFFECT SNOW ADVISORY UNTIL 7 AM EST /6 AM CST/ THIS MORNING FOR MIZ001>004-009-084. LAKE EFFECT SNOW WARNING UNTIL 10 AM EST THIS MORNING FOR MIZ005. LAKE EFFECT SNOW WARNING UNTIL 1 PM EST THIS AFTERNOON FOR MIZ013-014. LAKE EFFECT SNOW WARNING UNTIL 10 PM EST THIS EVENING FOR MIZ006- 007-085. LAKE SUPERIOR... GALE WARNING UNTIL 7 AM EST THIS MORNING FOR LSZ249>251-266-267. LAKE MICHIGAN... GALE WARNING UNTIL 7 AM EST THIS MORNING FOR LMZ221-250. && $$ DISCUSSION...KF AVIATION...JLA MARINE...ROLFSON mi AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY NATIONAL WEATHER SERVICE RAPID CITY SD 906 AM MST FRI NOV 21 2008 .DISCUSSION...CURRENT SURFACE MAP PLACES LOW PRESSURE ACROSS NORTHWEST SOUTH DAKOTA. SNOW INCREASING IN COVERAGE ACROSS THE AREA...FROM THE BLACK HILLS INTO NORTHWEST SOUTH DAKOTA. MEANWHILE...DRY SLOT WORKING INTO SOUTHWEST SOUTH DAKOTA WITH MOSTLY SUNNY SKIES. 12Z NAM/RUC CONTINUE TO SHOW HEAVIEST SNOW ACROSS FAR NORTHWEST SOUTH DAKOTA THROUGH THIS EVENING AS UPPER LEVEL SPINS ACROSS THE AREA. HIGH FROUDE/MOISTURE FOR UPSLOPE SNOW. WITH A WEST-NORTHWEST WIND...HIGHEST AMOUNTS SHOULD BE IN THE O`NEIL PASS/FOUR CORNERS AREA. RAPID CITY SHOULD REMAIN DOWNSLOPED MUCH OF THE DAY...THOUGH CAN NOT RULE OUT QUICK BURST OF CONVECTIVE SNOW. FORECAST UPDATED TO ADJUST POPS/SNOW AMOUNTS. LEFT HEADLINES ALONG FOR NOW...BUT MAY NEED TO ADJUST SOUTHWARD IF NORTHWARD MOVEMENT OF THE SNOW STALLS. && .AVIATION...IFR/LIFR CIGS/VSBY WILL CONTINUE ACROSS PORTIONS OF NORTHEAST WYOMING/NORTHWEST SOUTH DAKOTA THROUGH THE DAY WITH SNOWFALL. MAINLY VFR ACROSS FAR SOUTHWEST/SOUTH CENTRAL SOUTH DAKOTA WITH A FEW MVFR RAIN/SNOW SHOWERS THIS AFTERNOON. && .PREV DISCUSSION... /ISSUED 314 AM MST FRI NOV 21 2008/ DISCUSSION...09Z SFC ANALYSIS SHOWS TROUGH EXTENDING FROM ALBERTA THROUGH MONTANA AND INTO SOUTHEASTERN WYOMING WITH A TIGHT SFC PRESSURE GRADIENT OVER NORTHEASTERN WYOMING AND WESTERN SOUTH DAKOTA...RESULTING IN BREEZY TO WINDY CONDITIONS. WATER VAPOR SAT IMAGERY SHOWS UPPER TROUGH OVER WESTERN MONTANA. THE UPPER TROUGH WILL DEEPEN AND FORM A CLOSED UPPER LOW WHICH WILL DROP QUICKLY SOUTHEAST ACROSS WESTERN SOUTH DAKOTA TODAY. A 100KT 300MB JET STREAK ROUNDING THE BASE OF THE TROUGH WILL INCREASE SYNOPTIC SCALE LIFT ACROSS THE AREA THIS MORNING INTO THIS AFTERNOON...AS INDICATED BY AREA OF SNOW THAT HAS DEVELOPED OVER CENTRAL AND EASTERN MONTANA. NAM AND GFS STILL INDICATING A SLIGHTLY DIFFERENT TRACK FOR THE UPPER LOW WITH THE NAM SHOWING THE GREATEST SNOWFALL POTENTIAL FOR OUR AREA WITH 2 TO 4 INCHES OVER HARDING AND PERKINS COUNTIES IN NORTHWESTERN SOUTH DAKOTA TODAY INTO THIS EVENING. EVEN IF THE SNOW AMOUNTS END UP A BIT LOWER...NORTHWEST WINDS OF 15 TO 25 MPH MAY CAUSE REDUCED VISIBILITIES DUE TO BLOWING SNOW. THEREFORE...FELT IT PRUDENT TO HIGHLIGHT THE POTENTIAL FOR POOR TRAVEL CONDITIONS OVER NORTHWESTERN SOUTH DAKOTA WITH A WINTER WEATHER ADVISORY FOR TODAY INTO THIS EVENING. IT LOOKS LIKE THE HEAVIEST SNOW WILL FALL IN A NARROW BAND NEAREST THE ND/SD BORDER THIS AFTERNOON...BECOMING LIGHTER THIS EVENING AS THE SYSTEM SHIFTS OFF TO THE EAST. AN UPPER RIDGE CROSSES THE AREA ON SATURDAY...LEADING TO DRY WEATHER. ANOTHER TROUGH WILL BRING COLDER AIR INTO THE REGION ON SUNDAY. POSSIBLY ENOUGH MOISTURE FOR A FEW FLURRIES OR LIGHT SNOW SHOWERS OVER PORTIONS OF NE WY AND NW SD LATE SATURDAY NIGHT AND SUNDAY. EXTENDED...AN UPPER LEVEL RIDGE WILL BUILD OVER THE AREA FOR THE BEGINNING INTO THE MIDDLE OF THE UPCOMING WORK WEEK. THIS WILL BRING DRY CONDITIONS ALONG WITH ABOVE AVERAGE TEMPERATURES. AVIATION...AN AREA OF LOW STRATUS BRINGING MVFR CIGS CAN BE EXPECTED OVER NORTHEAST WYOMING INTO PARTS OF THE BLACK HILLS AND FAR SOUTHWEST SOUTH DAKOTA THIS MORNING. AN APPROACHING DISTURBANCE WILL BRING SNOW TO MANY PARTS OF THE AREA THROUGH THIS EVENING... PARTICULARLY OVER NORTHWEST SOUTH DAKOTA. SOME BLOWING SNOW IS EXPECTED OVER THIS AREA...WITH VISIBILITY DROPPING TO IFR AT TIMES. && .UNR WATCHES/WARNINGS/ADVISORIES... SD...WINTER WEATHER ADVISORY UNTIL 11 PM MST THIS EVENING FOR HARDING- PERKINS. WY...NONE. && $$ sd AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LUBBOCK TX 536 AM CST FRI NOV 21 2008 .AVIATION... VFR CONDITIONS TO CONTINUE NEXT 24 HOURS. LIGHT NORTHEAST WINDS TO VEER TO THE SOUTH AND INCREASE DURING THE DAY AS UPPER LEVEL DISTURBANCE MOVES INTO THE NORTHERN PLAINS TODAY INDUCING A LEE SIDE LOW AT THE SURFACE OVER SOUTHEAST COLORADO. && .PREV DISCUSSION... /ISSUED 415 AM CST FRI NOV 21 2008/ SHORT TERM... RATHER BENIGN WEATHER FOR THE SHORT TERM. BOTH RUC AND NAM MODELS IN GOOD AGREEMENT THAT LOW CLOUDS NEAR THE NEW MEXICO BORDER WILL REMAIN THERE AND GRADUALLY DISSIPATE THIS MORNING. SHORTWAVE CURRENTLY SEEN ON WATER VAPOR...MOVING INTO WESTERN MONTANA TO CONTINUE MOVING EAST INTO SOUTH DAKOTA BY THIS EVENING THEN INTO IOWA BY SATURDAY MORNING. THIS FEATURE TO AID IN DEVELOPING A LEE SIDE LOW OVER SOUTHEAST COLORADO. THIS WITH SURFACE HIGH ALSO MOVING TO THE EAST WILL HAVE WINDS VEER AROUND TO THE SOUTH LATER THIS MORNING. WIND WILL ALSO PICK UP AND BECOME A BIT GUSTY AS SURFACE GRADIENT TIGHTENS. TEMPERATURES TO REMAIN ON THE COOL SIDE WITH WARMER TEMPERATURES OVER NORTHWEST ZONES WHERE WINDS EXPECTED TO BE MORE SOUTHWEST AND STRONGER. ALTHOUGH SKIES EXPECTED TO BE CLEAR AGAIN TONIGHT...WITH SOUTHERLY AND SLIGHTLY STRONGER WINDS ..LOWS TO BE SLIGHTLY WARMER THEN THIS MORNING. LONG TERM... MODERATING TREND WILL CONTINUE THROUGH THE WEEKEND AS FLAT RIDGE ALOFT PROMOTES SURFACE LOW PRESSURE OVER SOUTHERN HIGH PLAINS. DOWNSLOPE WARMING SHOULD INCREASE SUNDAY AS PRESSURE FALLS FURTHER IN RESPONSE TO THE NEXT CLIPPER-TYPE LOW DIVING SOUTHEAST THROUGH ALBERTA. THIS SYSTEM WILL CROSS THE GREAT LAKES MONDAY PULLING THE NEXT SURFACE COLD FRONT SOUTHWARD THR0UGH THE AREA PRIOR TO DAYBREAK MONDAY. CURRENT EXPECTATIONS CALL FOR MODEST SURFACE PRESSURE RISES EARLY MONDAY MORNING RESULTING IN BREEZY POST FRONTAL WINDS. TEMPERATURES MONDAY ALSO ANTICIPATED TO FALL ONLY MODESTLY. CONTINENTAL PATTERN IS THEN EXPECTED TO BEGIN AMPLIFICATION AS A SERIES OF PACIFIC LOWS DIG ONTO THE CALIFORNIA COAST SENDING HEIGHTS BACK UP ACROSS SOUTHERN HIGH PLAINS THROUGH MID-WEEK. PATTERN SHOULD REMAIN PROGRESSIVE INITIALLY WITH FLOW ALOFT BECOMING SOUTHWESTERLY ON WEDNESDAY. MOISTURE LEVELS SHOULD IMPROVE WITH CURRENT LONG RANGE GUIDANCE SUGGESTING ENOUGH MOISTENING FOR PRECIPITATION CONSIDERATION AS EARLY AS WEDNESDAY AS INITIAL DISTURBANCE SHEARS NORTHEAST ACROSS ROCKIES FROM THE CALIFORNIA COAST. TO US THIS WAVE LOOKS TOO OPEN WHILE ATMOSPHERE LIKELY WILL NEED MORE MOISTURE DEEPENING AS WELL. ANOTHER STRONGER THOUGH STILL SOMEWHAT OPEN WAVE IS EXPECTED TO PROGRESS FROM THE WEST COAST OVER SOUTHERN PLAINS THANKSGIVING DAY. THIS WAVE HAS SHOWN GOOD CONTINUITY ON ENSEMBLE RUNS FOR THE PAST WEEK...AND AT THIS POINT HAS CREDIBILITY ENOUGH TO WARRANT INITIAL LOW END SHOWER CHANCES AS MOISTURE EXPECTED TO BE ADEQUATE AS WELL. TEMPERATURE PROFILE CLEARLY FAVORS LIQUID THIS FAR OUT AND ALSO SUGGESTS PRECIPITATION MAY BE CONVECTIVE. THIS WAVE SHOULD LIFT TO THE EAST-NORTHEAST THURSDAY NIGHT OR EARLY FRIDAY... WITH MODEL TIMING ISSUES FACTORING INTO UNCERTAINTY. MCQUEEN && .PRELIMINARY POINT TEMPS/POPS... FRIONA 46 26 62 31 69 / 0 0 0 0 0 TULIA 45 26 61 31 67 / 0 0 0 0 0 PLAINVIEW 45 27 61 32 69 / 0 0 0 0 0 LEVELLAND 45 28 62 32 70 / 0 0 0 0 0 LUBBOCK 46 29 61 35 71 / 0 0 0 0 0 DENVER CITY 46 30 64 35 72 / 0 0 0 0 0 BROWNFIELD 47 30 63 33 72 / 0 0 0 0 0 CHILDRESS 48 29 59 35 69 / 0 0 0 0 0 SPUR 48 31 62 35 70 / 0 0 0 0 0 ASPERMONT 50 31 63 40 71 / 0 0 0 0 0 && .LUB WATCHES/WARNINGS/ADVISORIES... NONE. && $$ 08 tx AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE SPOKANE WA 413 AM PST FRI NOV 21 2008 .SYNOPSIS... ANOTHER COLD FRONT WILL MOVE THROUGH THE INLAND NORTHWEST TONIGHT. PRECIPITATION AMOUNTS WILL GENERALLY BE LIGHT WITH THIS QUICK MOVING FRONTAL SYSTEM. STRONG HIGH PRESSURE WILL BRING DRY AND SEASONABLY COOL WEATHER SUNDAY AND MONDAY...AND THE WEATHER PATTERN WILL CONTINUE TO BE RATHER QUIET THROUGH MOST OF NEXT WEEK. && UPDATED AVIATION DISCUSSION .DISCUSSION... ISSUED 249 AM TODAY AND TONIGHT...EARLY MORNING WATER VAPOR IMAGERY SHOWS THE UPPER TROUGH AXIS (WITH YESTERDAY`S FRONT) HAS FRACTURED AND MOVED INTO CENTRAL MONTANA. POST FRONTAL...OROGRAPHIC SNOW SHOWERS REMAIN OVER THE MOUNTAINS OF THE IDAHO PANHANDLE...BUT THESE SHOWERS WILL DIMINISH QUICKLY. THE NAM FORECASTS THE 500MB COLD POOL (-25C TO -28C) QUICKLY EXITING THE IDAHO PANHANDLE BETWEEN 12Z-15Z...WHICH SHOULD BRING AN END TO THE CONVECTIVE SNOW THIS MORNING. GUSTY WINDS OVER THE PALOUSE AND COLUMBIA BASIN SHOULD ALSO DIMINISH QUICKLY THIS MORNING. SURFACE PRESSURE TENDENCIES SHOW SIGNIFICANT PRESSURE RISES OVER EASTERN WASHINGTON. THE RUC 850MB WIND ANALYSIS ALSO SHOWS THE LOW LEVEL WIND FIELD WEAKENING CONSIDERABLY. GUSTS AS HIGH AS 41KTS WERE MEASURED BY THE PULLMAN ASOS EARLY THIS MORNING. BY 15Z...WINDS SHOULD BE IN THE 10-15KT RANGE AND BEGIN TO BACK TO A MORE SOUTHERLY DIRECTION THIS MORNING...THEN BECOME EAST BY LATE IN THE DAY. THE NEXT STORM SYSTEM SHOWS UP ON THE MORNING WATER VAPOR AS A WELL DEFINED BAROCLINIC LEAF NEAR 140W. THE 00Z RUNS OF THE NAM AND GFS WERE IN REMARKABLY GOOD AGREEMENT WITH THE TIMING OF THE COLD FRONT TONIGHT. THE 06Z GFS HAS TRENDED A COUPLE HOURS SLOWER AND LOOKING AT SATELLITE TRENDS THIS LATER MODEL RUN IS PREFERRED. THIS FRONTAL SYSTEM WILL NOT PRODUCE AS MUCH PRECIPITATION AS YESTERDAY`S STORM. THE VORTICITY CENTER IS EXPECTED TO TRACK FURTHER NORTH...AND THE BEST Q-VECTOR CONVERGENCE IS FORECAST TO BE OVER SOUTHERN BRITISH COLUMBIA. SO EVEN THOUGH SNOW LEVELS OVER THE WATERVILLE PLATEAU INTO THE OKANOGAN HIGHLANDS WILL BE LOW ENOUGH FOR SNOW IN THE LOW ELEVATIONS...PRECIPITATION AMOUNTS WILL NOT LIKELY BE ENOUGH TO PRODUCE MEASURABLE SNOW. WITH HELP FROM OROGRAPHIC LIFT...THE CREST OF THE CASCADES AND THE MOUNTAINS ALONG THE CANADIAN BORDER CAN EXPECT AN INCH OR TWO TONIGHT INTO TOMORROW MORNING...MAINLY ABOVE 3000 FEET. /GKOCH SATURDAY THROUGH MONDAY...YET ANOTHER VERY DEEP IMPINGEMENT OF STRATOSPHERIC AIR INTO THE MID AND EVEN LOWER LEVELS OF THE ATMOSPHERE IS EVIDENT OVER THE PACIFIC THIS MORNING AS WATER VAPOR IMAGERY SHOWS EXTREMELY STRONG DRYING ENCROACHING ON 140W AS OF 10Z. PV FIELDS FROM THE 00Z MODELS` 12 HOUR FORECASTS INDICATE SOME LACK OF RESOLUTION OF THE TROPOPAUSE UNDULATION/FOLD OVER THE PACIFIC WITH THE BIAS OF THE MODELS GENERALLY TOWARD THE WEAK/FAST SIDE WHEN COMPARED WITH WATER VAPOR IMAGERY. THE NET RESULT IS A SLOW DOWN IN THE FORWARD PROGRESS OF THE AFOREMENTIONED WAVE ACROSS THE NORTHWESTERN PORTION OF THE COUNTRY AS IT GRADUALLY SHEARS OUT AND WEAKENS ONCE IT PUSHES ON SHORE. BOTH THE ECMWF AND UKMET SHOWED AT LEAST SOME SEMBLANCE OF A STRUNG OUT TROPOPAUSE FOLD SIGNATURE IN THEIR PV FIELDS WHEREAS THE GFS INDICATED A MORE BIMODAL PV DISTRIBUTION SEPARATING THE FIELD PREMATURELY INTO TWO DISTINCT VORTICES OVER THE PACIFIC...SO THE FORECAST THIS MORNING FAVORS THE ECMWF AND UKMET CONSENSUS. IN PROCEEDING WITH THE ECMWF/UKMET CONSENSUS...THE MAIN VORTEX SHIFTS ACROSS THE AREA BETWEEN 00Z AND 12Z SATURDAY WITH THE BEST SYNOPTIC DYNAMICS ALREADY EMERGING INTO THE FRONT RANGE OF THE CANADIAN ROCKIES BY SATURDAY MORNING. HOWEVER...THE TRAILING LOW AND MID-LEVEL FRONT AROUND THE SOUTHERN PERIPHERY OF THE SYSTEM LAG QUITE A BIT BEHIND THE MAIN SYSTEM. AS A RESULT...FRONTOGENESIS IN THE MID AND LOW LEVELS COUPLED WITH A STRUNG OUT FRONTAL ABSOLUTE VORTICITY FIELD AND NET VERTICAL UPWARD INCREASING PVA ALONG THE FRONTAL ZONE WILL RESULT IN MORE STRATIFORM RAINFALL STILL AFFECTING A PORTION OF THE EASTERN CWA THROUGH SATURDAY MORNING. HOWEVER...AS THE FRONT CLEARS THE AREA SATURDAY AFTERNOON...POPS WILL GRADUALLY COME DOWN AND PRECIPITATION WILL QUICKLY TRANSITION INTO THE POST-FRONTAL SHOWERY UPSLOPE VARIETY INTO THE IDAHO PANHANDLE MOUNTAINS. BEHIND THE FRONT...COLDER AND DRIER AIR GRADUALLY FILTERS IN. THE DRIER AIR LOOKS A BIT MORE DOMINANT ON THE 00Z RUNS THAN IT DID AT THIS TIME YESTERDAY WITH NO MODEL REALLY INDICATING SIGNIFICANT AREAS OF BOUNDARY LAYER SATURATION REPRESENTATIVE OF FOG. HOWEVER...WITH DECOUPLING AND STRONG RADIATIONAL COOLING UNDER THE INCOMING SYNOPTIC SCALE RIDGE AXIS ON ALL MODELS...LOW-LYING AREAS WILL CERTAINLY STAND A CHANCE AT SOME FOG DEVELOPMENT SATURDAY NIGHT INTO SUNDAY MORNING. THE NEXT SYSTEM TO APPROACH THE AREA WILL LIKELY HOLD OFF UNTIL AT LEAST MONDAY NIGHT IF NOT TUESDAY. HOWEVER...WITH THIS SYSTEM THE MODELS ARE HAVING SIGNIFICANT DIFFICULTY WITH STREAM SPLITTING AND THE HANDLING OF THE FOCUSING OF DEVELOPMENT ON THE NORTHERN OR SOUTHERN STREAM. AS A RESULT...THE FORECAST WAS LEFT LARGELY UNCHANGED BEYOND MONDAY. /FRIES && .AVIATION... LOW STRATUS WILL FLIRT WITH KGEG...KSFF...KPUW...AND KCOE BETWEEN 12Z AND 18Z. GUSTY SURFACE WINDS HAVE SUFFICIENTLY MIXED THE BOUNDARY LAYER OVERNIGHT TO KEEP MOST OF THE STRATUS AWAY FROM THESE AIRPORTS...BUT AS THE PRESSURE GRADIENT RELAXES THIS MORNING...STRATUS OVER THE PANHANDLE MOUNTAINS MAY BUILD WESTWARD. SINCE KCOE IS CLOSEST TO THE MOUNTAINS...THIS TERMINAL WILL HAVE THE BEST CHANCE OF EXPERIENCING IFR CEILINGS THIS MORNING. THE OTHER SITES MAY EXPERIENCE SOME RAGGED TEMPORARY STRATUS...BUT IFR WILL NOT LIKELY BE THE PREVAILING CONDITION. THE NEXT COLD FRONT WILL ENTER EASTERN WASHINGTON AFTER 07Z AND BRING THE CHANCE FOR LIGHT PRECIPITATION. /GKOCH && .PRELIMINARY POINT TEMPS/POPS... SPOKANE 42 31 43 25 43 25 / 0 40 10 0 0 0 COEUR D`ALENE 44 33 43 27 43 26 / 10 50 40 10 0 0 PULLMAN 46 36 45 28 46 28 / 0 30 30 10 0 0 LEWISTON 51 38 50 30 51 30 / 0 10 20 10 0 0 COLVILLE 39 31 41 23 39 24 / 10 40 10 0 0 0 SANDPOINT 43 32 41 27 42 24 / 20 50 30 10 0 0 KELLOGG 40 34 39 29 40 27 / 40 40 40 20 0 0 MOSES LAKE 46 31 48 26 45 26 / 0 20 0 0 0 0 WENATCHEE 42 35 46 28 42 27 / 0 20 0 0 0 0 OMAK 41 32 44 24 42 24 / 0 30 0 0 0 0 && .OTX WATCHES/WARNINGS/ADVISORIES... ID...NONE. WA...NONE. && $$ wa AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 430 PM EST FRI NOV 21 2008 .SYNOPSIS... 12Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW DEEP TROF OVER ERN NAMERICA DOWNSTREAM OF RDG OVER THE ROCKIES. COLD NNW FLOW (12Z H85 TEMP -25C AT YPL VS -18C AT GRB) BTWN ARCTIC HI PRES JUST E OF LK WINNIPEG AND LO PRES OVER SE CAN OVER THE RELATIVELY WARM WATERS OF LK SUP (5C OVER THE W TO 8C OVER THE E PER GLERL ANALYSIS) CONTINUES TO GENERATE LK EFFECT SHSN ACRS UPR MI. THE HEAVIER SHSN ARE NOTED OVER THE E HALF WITH LONGER FETCH AVBL OVER THE WATER AS WELL AS SOME MOISTENING OFF LK NIPIGON OF FAIRLY DRY AIRMASS SHOWN ON 12Z YPL RAOB. BUT LES ALSO CONTINUES OVER THE W DESPITE LO INVRN BASE ARND H9-925 AS SHOWN ON 12Z RAOB FM INL AND 12Z TAMDAR SDNG FM YQT. LES BANDS ARE MORE WELL DVLPD TDAY THAN YDAY OVER THE W WITH SOME CONFLUENCE BTWN LAND BREEZE FLOW OFF NW WI AND MORE NNW FLOW OVER WRN LK AS WELL AS SHALLOW MSTR BLO THE INVRN BASE SHOWN ON INL RAOB SUPPORTING AREA OF SC/-SN OVER NE MN MAKING BANDS A BIT MORE WELL DEFINED. CALLS TO SPOTTERS IN ONTONAGON COUNTY SUG THE SN UNDER THE BANDS IS RELATIVELY LGT WITH NO MORE THAN AN INCH EVERY 3-4 HOURS DESPITE RELATIVELY LO VSBYS AT TIMES SHOWN BY CMX/IWD OBS. A SHRTWV IS NOTED OVER THE NRN PLAINS RIDING THRU THE MEAN UPR RDG AXIS. && .SHORT TERM DISCUSSION (TNGT THRU SAT)... MAIN FCST CONCERNS TNGT ARE LES TRENDS/AMTS/NEED TO CHG GOING HEADLINES. FOCUS FOR SAT SHIFTS TO MAINLY TEMPS WITH SFC HI PRES RDG TO THE W FCST FINALLY TO EASE INTO THE GRT LKS. FOR TNGT...LOOK FOR RISING UPR HGTS AS LARGER SCALE MODELS SHOW UPR TROF OVER ERN NAMERICA GRDLY EDGING EWD...ALLOWING SFC RDG AXIS TO THE W TO DRIFT INTO THE UPR GRT LKS. WITH SLOWLY DIMINISHING WINDS/ LOWERING INVRN BASE WITH APRCH OF RDG...EXPECT LES BANDS IN THE NW WINDS SN BELTS THIS EVNG TO GRDLY WEAKEN WITH TIME. ONCE WINDS REALLY DIMINISH AFT 06Z...SOME MESOSCALE WIND IMPACTS MAY BEGIN TO SHOW UP. LOCAL WRF-ARW/12Z NAM/12Z CNDN AND ESPECIALLY THE RUC13 SHOW NE LAND BREEZE OFF ONTARIO ENHANCING THE LLVL CNVGC IN ALGER COUNTY WITH VORTEX DVLPG NEAR P53. THERE ARE ALSO HINTS OVER THE WRN COUNTIES THAT CONFLUENCE BTWN DVLPG LAND BREEZE OFF NW WI/SLY FLOW TO THE W OF SFC RDG AXIS AND LINGERING NNW FLOW OVER CNTRL LK SUP MAY GENERATE BAND OF SHSN IN THAT AREA THAT GRDLY SHIFTS TO THE NE WITH SYNOPTIC WSHFT TO THE SSW. WL CARRY NO MORE THAN CHC POPS FOR THIS EVENT OVER THE W GIVEN RELATIVELY LO INVRN BASE THERE ALREADY. BUT WL MAINTAIN HIER LIKELY POPS IN ALGER COUNTY FOR A LONGER PD. AS FOR HEADLINES...OPTED TO MAINTAIN GOING ENDING TIME OF 03Z FOR LUCE COUNTY BUT EXTENDED GOING/VERIFIED WRNGS FOR ALGER/NRN SCHOOLCRAFT LONGER TO ACCOUNT FOR PSBL SHARPER CNVGC IN PRESENCE OF HIER INVRN (ARND H825 THRU 09Z SAT AT P53 PER NAM FCST) THAN WOULD BE EXPECTED OVER THE W. OTRW...EXPECT THE LOWEST MIN TEMPS NEAR THE WI BORDER WHERE CLRG IS MOST LIKELY AWAY FM LK SUP. WL TEND AOB THE LO END OF MOS GUIDANCE IN THESE AREAS TO INCLUDE SOME SUB ZERO READINGS. MORE NLY H925 FLOW OFF LK SUP MAY MAINTAIN MORE CLD/HIER TEMPS OVER THE NCNTRL. AS THE SFC RDG AXIS SHIFTS TO THE E ON SAT WITH A SLOW DEPARTURE OF THE ERN TROF...THE LLVL FLOW WL TURN TO THE S AND END LINGERING LES. OTRW...FCST SDNGS SHOW DRY LLVLS. SO EXCEPT FOR SOME HI CLD ON THE NRN FRINGES OF SHRTWV NOW OVER THE NRN PLAINS THAT IS PROGGED TO DROP SEWD THRU THE UPR MIDWEST...THE DAY WL BE MOSUNNY. THE DAY WL BE WARMER THAN TDAY WITH DEPARTURE OF H85 THERMAL TROF...BUT HI STABILITY OF FCST SDNGS/TEMPS OBSVD UPSTREAM THIS AFTN IN THE NRN PLAINS SUG THE LO END OF MOS GUIDANCE FOR HI TEMPS WL BE MORE APPROPRIATE. && .LONG TERM...(SATURDAY NIGHT THROUGH FRIDAY) SATURDAY NIGHT INTO SUNDAY...THE NAM AND GFS WERE IN REASONABLE AGREEMENT WITH THE OVERALL WAA PATTERN DEVELOPING ACROSS THE WRN GREAT LAKES. 280K-290K ISENTROPIC LIFT (900-750 MB) MAY PROVIDE ENOUGH LOW LEVEL MOISTENING...PER MDL RH FOR POTENTIAL OF SOME PATCHY -FZDZ OVER THE WEST HALF OF THE CWA BTWN 06Z-18Z/SUN AS THE THE MOISTURE REMAINS BLO THE -8C ISOTHERM. WITH WSW FLOW...DOWNSLOPE AREAS CLOSER TO LAKE SUPERIOR WOULD BE LESS SUSCEPTIBLE TO ANY FRZG PCPN. BY LATE SUNDAY...SOME LIGHT SNOW MAY MOVE INTO WRN UPPER MI...PER LCLY RUN REGIONAL WRF/ARW AND THE GFS SUPPORTED BY WEAK TO MODERATE QVECTOR CONV AHEAD OF A MID LEVEL TROUGH MOVING OUT OF THE NRN PLAINS. SUNDAY NIGHT THROUGH MONDAY NIGHT...PER 12Z GFS AND 00Z ECMWF...A SHRTWV TROUGH IS EXPECTED TO DROP SE FROM MANITOBA THROUGH THE GREAT LAKES. FALLING HEIGHTS AND MODERATE QG FORCING WITH THE MID LEVEL LOW WILL SUPPORT LIGHT SNOW CHANCES ACROSS THE AREA SUN NIGHT INTO EARLY MON. BEHIND THE LOW...SOME LAKE ENHANCED SNOW MAY BE POSSIBLE WITH CYCLONIC NRLY FLOW DEVELOPING AND 850 MB TEMPS DROPPING TO AROUND -8C. WITH ONLY MARGINAL INSTABILITY/LIFT FCST...MAINLY LIGHT ACCUMULATIONS WOULD BE EXPECTED. TUESDAY...AS THE DEEPER MOISTURE DEPARTS AND 850 MB TEMPS ONLY REMAIN NEAR -10C...PER ECMWF/GFS BLEND...ANY LES SHOULD REMAIN ON THE LIGHT SIDE. WEDNESDAY-FRIDAY...MID LEVEL AND SFC RIDGING BUILDS INTO THE WRN LAKES BRINGING MAINLY DRY WEATHER. UNCERTAINTY BY THE END OF THE WEEK INCREASES WITH THE PATH/SPEED OF ANOTHER MID LEVEL LOW DROPPING SSE TOWARD THE GREAT LAKES. FOR NOW...THE GLOBAL MDLS AND GFS ENSEMBLE SUGGESTS THAT ANY PCPN WITH THIS FEATURE WOULD BE AFTER THE FCST PERIOD. && .AVIATION (FOR THE 18Z TAF ISSUANCE)... AT CMX...EXPECT MVFR CIGS TO PREDOMINATE THRU TNGT WITH LLVL MSTR IN NW FLOW UNDER RELATIVELY SHALLOW INVRN. THERE WL BE -SHSN WITH SOME OCNL IFR VSBYS THIS AFTN...BUT GRDL INFUSION OF DRIER LLVL AIR WITH ARPCH OF RDG AXIS FM THE W WL TEND TO MAINTAIN VFR VSBYS. THE ONLY EXCEPTION MAY BE LATE TNGT FOR A TIME WHEN LAND BREEZE CNVGC ALLOWS FOR MORE SGNFT -SHSN FOR A FEW HRS. CONDITIONS WL BE VFR ON SAT WITH DRY SLY FLOW TO THE W OF RDG AXIS PASSING TO THE E. AT SAW...GENERALLY VFR CIGS THIS AFTN WL TEND TOWARD MVFR WITH COMBINATION OF LOWERING SUBSIDENCE INVRN/VEERING FLOW TO MORE NNE JUST ABV THE SFC WITH APRCH OF HI PRES RDG TO CAUSE DVLPMNT OF LOWER CIG. MOIST LYR NEAR INVRN BASE/NEAR SFC LYR WL BE TOO SHALLOW/DRY FOR ANY LES. CONDITIONS WL BE VFR ON SAT WITH DRY SLOW FLOW TO THE W OF RDG AXIS PASSING TO THE E. && .MARINE (FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)... A HIGH PRESSURE RIDGE CENTERED OVER THE MISSISSIPPI RIVER VALLEY WILL PUSH A RIDGE EASTWARD ACROSS THE UPPER GREAT LAKES THROUGH SUNDAY MORNING. NORTH TO NORTHWEST WINDS TO 30 KNOTS WILL DIMINISH THIS EVENING WITH THE APPROACH OF THE RIDGE. AS THE HIGH MOVES TOWARD THE ATLANTIC SEABOARD IN THE SOUTHEAST...A LOW OVER THE CANADIAN PRAIRIES WILL MOVE INTO THE UPPER GREAT LAKES. THIS LOW WILL MOVE SOUTHEAST TOWARD THE MID ATLANTIC STATES ON TUESDAY. NORTH WINDS IN THE WAKE OF THIS LOW WILL INCREASE TO 30 KNOTS LATE MONDAY INTO TUESDAY...WITH GALES POSSIBLE OVER PORTIONS OF THE EAST HALF. LOOK FOR A RIDGE OF HIGH PRESSURE TO FOLLOW INTO THE LOWER GREAT LAKES FROM THE PLAINS. THE APPROACH OF THIS RIDGE WILL WEAKEN THE STRONG NORTH WINDS. && UPPER MICHIGAN... LAKE EFFECT SNOW WARNING UNTIL 7 AM EST SATURDAY FOR MIZ006-085. LAKE EFFECT SNOW WARNING UNTIL 10 PM EST THIS EVENING FOR MIZ007. LAKE SUPERIOR...NONE. LAKE MICHIGAN...NONE. && $$ SYNOPSIS/SHORT TERM...KC LONG TERM...JLB AVIATION...KC MARINE...KC mi AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE MARQUETTE MI 1235 PM EST FRI NOV 21 2008 UPDATED FOR 18Z TAF ISSUANCE .DISCUSSION... ISSUED AT 500 AM EST SEVERAL HEADLINES EXPIRE AT 7 AM EST THIS MORNING. THIS SEEMS REASONABLE FOR THE WESTERN COUNTIES GIVEN THE NORTHWESTERLY FLOW...AND GENERALLY DRY AIR UPSTREAM. CONVERGENCE EAST INCREASES TODAY...AS HIGH PRESSURE ROLLS TOWARDS WESTERN LAKE SUPERIOR. THE MOST DOMINATE BAND ON THE RADAR LOOKS TO STRETCH ALMOST PARALLEL TO MARQUETTE COUNTY...CROSSING INTO WESTERN ALGER COUNTY...AND OVER EBEN JUNCTION AND JUST EAST OF TRENARY. AN EASTERN PUSH TO THESE BANDS WILL CONTINUE TODAY. INCORPORATED BS ON LAND WHERE WIND GUSTS WHERE GREATER THAN 22KT...WHICH ENDED UP BEING MAINLY THIS MORNING NEAR LAKE SUPERIOR. ONE OF THE MAIN QUESTIONS IS WHEN LAKE EFFECT SNOW SHOWERS WILL END OVER THE CWA. OUT WEST...FOR GOGEBIC COUNTY THIS COULD BE AS EARLY AS 12Z THIS MORNING AS WNW WINDS BECOME MORE WESTERLY SIGNIFICANTLY LESSENING THE FETCH OVER LAKE SUPERIOR. THE RUC IS QUICKEST TO ALLOW FOR A WESTERLY WIND OVER GOGEBIC AND SOUTHERN ONTONAGON COUNTIES. HOWEVER...WESTERLY FLOW TAKES A BIT LONGER TO GET TO ONTONAGON COUNTY...WITH MODELS SHOWING 00Z AS THE CUT OFF POINT. ADDING TO THIS WILL BE THE NEXT BROAD SHORTWAVE MOVING MAINLY EST OF THE CWA LATE THIS AFTERNOON/EARLY THIS EVENING...ENHANCING SNOWFALL SLIGHTLY OVER THE EASTERN UPPER PENINSULA. TEMPERATURE WISE...THERE IS VERY LITTLE DIFFERENCE IN GUIDANCE VALUES...SO WILL GO WITH THE CONSENSUS FOR TODAY. A BLEND SEEMS REASONABLE FOR TONIGHT...AS THE NAM/MET DROPS TEMPERATURES TO 0F AND THE GFS/MAV DISPLAYS SINGLE DIGITS. OTHERWISE FOR THE WEEKEND...WILL ADJUST AFTERNOON HIGH TEMPERATURES UP A DEGREE OR TWO. HAVE SECOND GUESSED THIS DUE TO THE INFLUENCE OF THE SNOWPACK...AND IF THIS IS BEING HANDLED BY THE MODELS QUITE YET. HAVE LOW CONFIDENCE IN THE POTENTIAL FOR SNOW OR FREEZING DRIZZLE SATURDAY NIGHT INTO SUNDAY...ALTHOUGH IT IS ONLY 20 PERCENT. IF WE DO GET PRECIPITATION A MIX SEEMS REALISTIC...AS 850MB TEMPERATURES RISE TO THE -5 OR -6C OFF THE NAM AND GFS. THE 12Z/20 ECMWF WARMS TO -2 TO -3C OVER THE WESTERN PORTIONS OF THE CWA BY THE SAME TIME...12Z SUNDAY. INCREASED SKY COVER MONDAY AFTERNOON THOUGH TUESDAY...WITH NORTHERLY FLOW OFF LAKE SUPERIOR AND 850MB TEMPERATURES HOVERING NEAR -7 TO -10C. BY TUESDAY AFTERNOON WARM AIR WILL BE ENCROACHING ALOFT...RISING 850MB TEMPERATURES TO -6C OR WARMER...EFFECTIVELY MINIMIZING LAKE ENHANCED SNOW AND TO A LESSER EXTENT CLOUD COVER. && .AVIATION (FOR THE 18Z TAF ISSUANCE)... AT CMX...EXPECT MVFR CIGS TO PREDOMINATE THRU TNGT WITH LLVL MSTR IN NW FLOW UNDER RELATIVELY SHALLOW INVRN. THERE WL BE -SHSN WITH SOME OCNL IFR VSBYS THIS AFTN...BUT GRDL INFUSION OF DRIER LLVL AIR WITH ARPCH OF RDG AXIS FM THE W WL TEND TO MAINTAIN VFR VSBYS. THE ONLY EXCEPTION MAY BE LATE TNGT FOR A TIME WHEN LAND BREEZE CNVGC ALLOWS FOR MORE SGNFT -SHSN FOR A FEW HRS. CONDITIONS WL BE VFR ON SAT WITH DRY SLY FLOW TO THE W OF RDG AXIS PASSING TO THE E. AT SAW...GENERALLY VFR CIGS THIS AFTN WL TEND TOWARD MVFR WITH COMBINATION OF LOWERING SUBSIDENCE INVRN/VEERING FLOW TO MORE NNE JUST ABV THE SFC WITH APRCH OF HI PRES RDG TO CAUSE DVLPMNT OF LOWER CIG. MOIST LYR NEAR INVRN BASE/NEAR SFC LYR WL BE TOO SHALLOW/DRY FOR ANY LES. CONDITIONS WL BE VFR ON SAT WITH DRY SLOW FLOW TO THE W OF RDG AXIS PASSING TO THE E. && .MARINE (FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)... FREQUENT GALE FORCE GUSTS OVER ERN LAKE SUPERIOR WILL END BEFORE SUNRISE AS PRES GRADIENT GRADUALLY RELAXES WITH HIGH PRES RIDGE EDGING TOWARD THE UPPER LAKES. THE RIDGE WILL PASS ACROSS LAKE SUPERIOR TONIGHT AND SAT MORNING...PROVIDING A PERIOD OF LIGHT WINDS GENERALLY UNDER 15 KNOTS. NEXT ROUND OF STRONG WINDS (AROUND 30KT) WILL DEVELOP MON THRU EARLY TUE MORNING IN THE WAKE OF LOW PRES DIVING SE THRU THE UPPER GREAT LAKES. STRONGEST WINDS WILL OCCUR OVER CNTRL AND ERN LAKE SUPERIOR. NOT OUT OF THE QUESTION THAT GALES COULD DEVELOP. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... LAKE EFFECT SNOW WARNING UNTIL 10 PM EST THIS EVENING FOR MIZ006-007-085. LAKE EFFECT SNOW WARNING UNTIL 1 PM EST THIS AFTERNOON FOR MIZ014. && $$ DISCUSSION...KF AVIATION...KC MARINE...ROLFSON mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN 249 PM CST FRI NOV 21 2008 .DISCUSSION... THE SHORTWAVE TROUGH ENTERING THE WESTERN DAKOTAS PER 20Z WATER VAPOR IMAGERY WILL BE THE FOCUS LOCALLY OVER THE NEXT 18 HOURS...AS IT CLOSES OFF AND SLIDES EAST/SOUTHEAST ACROSS SOUTHERN MN. ASSOCIATED 850-700MB OMEGA AND 2D FRONTOGENESIS BLOSSOM OVER THE SOUTHERN CWA AROUND 03Z...BUT EXPECT THE BULK OF THE SNOWFALL TO OCCUR BETWEEN 06Z AND 12Z WHEN THE LOW LEVEL SATURATION OCCURS. THE DYNAMICS...WHILE BRIEFLY IMPRESSIVE...ARE SOMEWHAT OUT OF SYNC WITH THE ARRIVAL OF THE LOW LEVEL MOISTURE...SO SNOWFALL ACCUMULATIONS OF ONE INCH OR LESS STILL APPEAR REASONABLE ALONG/SOUTH OF THE MN RIVER VALLEY. THIS IS SUPPORTED BY NAM/GFS/RUC PROGGED COBB OUTPUTS FOR KFRM AND KRWF. TEMPERATURES AT WESTERN CWA LOCATIONS WILL LIKELY REMAIN ELEVATED IN THE LOW 20S TONIGHT...ESPECIALLY CONSIDERING THE CLOUD COVER AND WARM AIR ADVECTION. EASTERN AREAS WILL HAVE THE POTENTIAL TO DIP INTO THE SINGLE DIGITS AGAIN...ESPECIALLY ACROSS WEST CENTRAL WI. LOW/MID CLOUDS WILL LINGER ON SATURDAY...BUT TEMPERATURES WILL MODERATE TO AROUND FREEZING. TEMPERATURES WILL WARM EVEN MORE ON SUNDAY AHEAD OF AN APPROACHING TROUGH...WITH HIGHS IN THE UPPER 30S AND LOWER 40S EXPECTED. THE RELATED COLD FRONT PASSES ACROSS THE CWA ON SUNDAY AFTERNOON/NIGHT...AS SHORTWAVE ENERGY ON THE WESTERN PERIPHERY OF AN AMPLIFYING EASTERN CONUS TROUGH STREAMS ACROSS MN AND WI. THE DEEPER MOISTURE WILL BE PRESENT ACROSS THE EASTERN CWA WHERE 30 POPS WERE PRESERVED...WHILE 20 POPS WERE ADEQUATE ELSEWHERE. THE EXTENDED PORTION OF THE FORECAST WILL FEATURE DRY WEATHER WITH NEAR TO ABOVE NORMAL TEMPERATURES THROUGH THE THANKSGIVING HOLIDAY...AS THE UPPER MIDWEST EXPERIENCES MID LEVEL RIDGING WHILE WEDGED BETWEEN CYCLONES OVER BOTH COASTS. && .AVIATION.../18Z TAF ISSUANCE/ VFR CONDITIONS STILL PREVAILING INTO TONIGHT WITH DEPARTING HIGH PRESSURE..AND DRY SSE FLOW ON THE BACK SIDE OF THE HIGH. HOWEVER...A SIGNIFICANT WAVE OVER MT IS FORECAST TO TRACK ESE TOWARD SE SD AND NW IA LATER TONIGHT. THIS WILL CAUSE SOME SNOW OVER SW MN AND FAR SOUTHERN MN AFTER MIDNIGHT. CEILINGS WILL LOWER TO MVFR AT KRWF WITH IFR VSBYS POSSIBLE FOR A FEW HOURS AFTER 09Z. MVFR OR LOW VFR CEILINGS WILL ALSO SPREAD INTO PARTS OF CENTRAL MN...INCLUDING KAXN...KSTC...AND KMSP. THIS WILL OCCUR MAINLY DURING THE LAST PART OF THE FORECAST PERIOD. AT THIS TIME...SNOW IS FORECAST ONLY FOR KRWF...BUT VRY LIGHT SNOW WITH P6SM CONDITIONS COULD AFFECT KMSP AND KSTC SATURDAY MORNING AS WELL. SSE WINDS WILL INCREASE BUT SPEEDS WILL MAINLY BE LESS THAN 15 KNOTS SUSTAINED. BEST CHANCE FOR HIGHER SPEEDS WILL BE AT KRWF AND KAXN. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...NONE. WI...NONE. && $$ LS/JPR mn AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RALEIGH NC 139 PM EST FRI NOV 21 2008 .SYNOPSIS... BLUSTERY NORTHWEST WINDS BEHIND A POLAR COLD FRONT OFF THE NORTH CAROLINA COAST WILL USHER ANOTHER ROUND OF VERY COLD AIR INTO THE REGION. COLDER THAN NORMAL TEMPERATURES WILL CONTINUE THROUGH THE WEEKEND. ANOTHER COLD FRONT WILL MOVE INTO THE AREA LATE MONDAY. && .NEAR TERM /THROUGH TONIGHT/... AS OF 1200 PM FRIDAY... SFC ANALYSIS THIS AFTERNOON SHOWED A 1010 MB LOW ABOUT 100 MILES EAST OF CAPE FEAR NC. STRONG (1040 MB) HIGH PRESSURE WAS CENTERED OVER EASTERN KS/OK AND MO/AR. THE 12Z GSO SOUNDING WAS QUITE COLD...WITH VERY STEEP (DRY ADIABATIC) LAPSE RATES FROM THE SFC THROUGH 750MB AND A 1000-850MB THICKNESS OF 1286M. ALOFT...AS OF 17Z THE LATEST RUC FORECAST DATA AND WV IMAGERY SHOW THE POTENT H5 SHORT WAVE BEGINNING TO ASSUME A NEUTRAL OR SLIGHTLY NEGATIVE TILT AS IT BEGINS TO CROSS CENTRAL NC. REST OF THIS AFTERNOON: FORECAST PRIMARILY ON TRACK WITH A SLIGHT CHANCE OF SNOW SHOWERS THROUGH ROUGHLY 2 TO 3 PM THIS AFTERNOON ALONG/EAST OF THE TRIANGLE. CURRENT RADAR IMAGERY SHOWS SCATTERED PRECIPITATION ECHOES JUST NORTH OF THE TRIANGLE INTO THE NORTHEAST COASTAL PLAIN. THESE CONVECTIVE SNOW SHOWERS HAVE DEVELOPED IN RESPONSE TO LINGERING LOW LEVEL MOISTURE...STEEP LOW LEVEL LAPSE RATES (ALLOWING MARGINAL INSTABILITY) AND UPPER LEVEL FORCING ASSOC/W THE POTENT SHORTWAVE BEGINNING TO GO NEUTRAL OR NEGATIVE TILT AS IT CROSSES CENTRAL NC. THE BEST CHANCE FOR SNOW SHOWER ACTIVITY WILL PROBABLY REMAIN IN FAR EASTERN NC THIS AFTERNOON WHERE UPPER LEVEL LIFT WILL REMAIN FAVORABLE LATER INTO THE AFTERNOON HOURS...ALTHOUGH WITH A BOUNDARY LAYER PROGRESSIVELY DRYING THROUGH THE DAY...WHETHER OR NOT ANYTHING ACTUALLY MAKES IT TO THE GROUND IS A VALID CONCERN. WILL LEAVE A SLIGHT CHANCE FLURRIES OR A BRIEF/LIGHT SNOW SHOWER IN THE FORECAST FROM THE TRIANGLE NORTHEAST TO RZZ SOUTH TO GSB THROUGH 2 OR 3 PM (AT LATEST) THIS AFTERNOON. EXPECTED PRECIPITATION TYPE SHOULD BE ALL SNOW... SINCE ANYTHING THAT IS HEAVY ENOUGH TO REACH THE GROUND SHOULD ALSO ALLOW ENOUGH EVAPORATIVE COOLING / MELTING TO KEEP THERMAL PROFILES IN THE LOWEST 500 TO 1500 FEET NEAR FREEZING. WITH TEMPERATURES HOLDING IN THE MID/UPPER 30S TO LOWER 40S...AND A NORTHWEST WIND OF 15-20 MPH WITH GUSTS UP TO 30 MPH (BASED ON FORECAST SOUNDINGS SHOWING 25 TO 30 KNOTS IN THE MIXED LAYER)... IT WILL BE QUITE CHILLY/BLUSTERY OUTSIDE FOR THE REMAINDER OF THIS AFTERNOON...ESPECIALLY AS WE GET CLOSE TO SUNSET AND TEMPERATURES BEGIN TO PLUMMET. TONIGHT: *VERY* COLD CONDITIONS EXPECTED TONIGHT. GIVEN A RATHER TIGHT PRESSURE GRADIENT THIS EVENING...A NORTHWEST BREEZE WILL LIKELY CONTINUE FOR SEVERAL HOURS AFTER SUNSET AS TEMPERATURES BEGIN TO PLUMMET INTO THE LOWER 30S AND UPPER 20S. THIS WILL ALLOW WIND CHILL VALUES TO DROP INTO THE TEENS TO LOWER 20S LATER THIS EVENING. WINDS SHOULD BEGIN TO SUBSIDE BY OR SHORTLY AFTER MIDNIGHT FROM WEST TO EAST AS THE HIGH PRESSURE CENTER CURRENTLY OVER THE LOWER MIDWEST APPROACHES THE SOUTHERN APPALACHIANS AND THE GRADIENT BEGINS TO RELAX. CLEAR SKIES SHOULD BE THE RULE WITH STRONG SUBSIDENCE ACROSS CENTRAL NC BEHIND THE DEPARTING UPPER LEVEL WAVE. WILL FORECAST LOW TEMPS CLOSE TO MOS GUIDANCE...RANGING FROM 19-24F ACROSS THE AREA. THE RECORD LOW TEMPERATURE FOR RDU (23F SET IN 1987) COULD EASILY BE TIED OR BROKEN TONIGHT. -VINCENT && .SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/... AS OF 325 AM FRIDAY... FOR SATURDAY/SATURDAY NIGHT: THE SURFACE HIGH SETTLES OVERHEAD AND THE 850 MB ANTICYCLONE DRIFTS OVERHEAD DURING THIS PERIOD. BUT FARTHER ALOFT... WHAT IS NOW A STRONG LOW PUSHING THROUGH THE INTERIOR PACIFIC NORTHWEST DIVES QUICKLY TO THE ESE... DAMPENING INTO AN OPEN WAVE AS IT APPROACHES NC. BUT NEVERTHELESS THIS WAVE REMAINS OF RESPECTABLE STRENGTH AND SHOULD STILL BRING IN APPRECIABLE MID AND HIGH CLOUDINESS SPREADING INTO NC SATURDAY AFTERNOON FROM THE NW. NAM/GFS FORECAST SOUNDINGS ARE IN GOOD AGREEMENT ON THIS. HAVE RAISED SKY COVER... STARTING THE INCREASE IN THE LATE MORNING. THICKNESSES START TO REBOUND AS THE 850 MB WARM FRONT HEADS TO OUR NE AND HIGHS SHOULD BE A DEGREE OR TWO WARMER... 42-46... HARDLY NOTICEABLE THOUGH GIVEN THE FRIGID START TO THE DAY. CLOUD COVER SHOULD DECREASE LATE SATURDAY NIGHT AS THE CLIPPER SHORTWAVE TROUGH EXITS. FORECAST LOWS IN THE LOW-MID 20S STILL LOOK GOOD. FOR SUNDAY/SUNDAY NIGHT: QUIET WEATHER FOR SUNDAY WITH SURFACE HIGH PRESSURE OVER THE EASTERN CAROLINAS AND BROAD (BUT WEAK) RIDGING IN THE MID LEVELS. THICKNESSES RISE INTO THE 1290-1300 METER RANGE... STILL WELL BELOW NORMAL HOWEVER... AND WE SHOULD SEE HIGHS STILL ABOUT 1-2 CATEGORIES BELOW NORMAL... 52-57. OUR NEXT WEATHER SYSTEM OF INTEREST... A POLAR VORTEX... DROPS INTO THE UPPER MIDWEST SUNDAY NIGHT... AND MID LEVEL FLOW INTO THE APPALACHIANS STARTS TO BECOME CYCLONIC AND STRENGTHENS... AS THE SURFACE HIGHS SHIFTS OFFSHORE. WE SHOULD SEE INCREASING HIGH CLOUDS THROUGH THE NIGHT BUT THIS SHOULD HAVE LITTLE IMPACT ON RADIATIONAL COOLING. EXPECT LOWS OF 28-32. -GIH && .LONG TERM /MONDAY THROUGH THURSDAY/... AS OF 455 AM FRIDAY... FOR MONDAY THROUGH TUESDAY: A COLD MID LEVEL VORTEX IS EXPECTED TO DROP SOUTHEAST ACROSS THE GREAT LAKES REGION DURING THIS PERIOD. THE LATEST GFS AND ECMWF ARE IN GOOD AGREEMENT ON A FASTER ARRIVAL OF THE NEXT COLD FRONT AS COMPARED TO YESTERDAY`S GUIDANCE... AND HAVE HASTENED THE CLOUD COVER INCREASE AND RAISED POPS MONDAY AFTERNOON TO HIGH CHANCES IN THE NW CWA... TAPERING TO SLIGHT CHANCE IN THE SOUTHEAST. CHANCE POPS WILL BE CONTINUED THROUGH MONDAY NIGHT AS THE COLD FRONT SWEEPS RAPIDLY EAST. THE FRONT SHOULD BE WELL OFF THE COAST BY TUESDAY MORNING... AND ONLY A SLIGHT CHANCE EAST OF I-95 IS EXPECTED EARLY TUESDAY MORNING. EXPECT CLEARING FROM THE WEST BY MIDDAY TUESDAY. HIGHS 55-62 MONDAY WITH THICKNESSES JUST 10-15 M BELOW NORMAL. HIGHS TUESDAY 52-57... A MUCH LESS MODEST COOLING THAN WE`VE SEEN WITH THESE RECENT COLD FRONT PASSAGES... AS THE INCOMING SURFACE AIR MASS HAS ITS SOURCE IN THE PACIFIC AND ROCKIES RATHER THAN CANADA. MORNING LOWS 37-43. FOR WEDNESDAY THROUGH THANKSGIVING DAY: STILL LOOKS QUIET AND COOL IN CENTRAL NC. THE MID LEVEL VORTEX SITS AND SPINS OVER THE INTERIOR NORTHEAST ACCORDING TO THE LATEST GFS AND ECMWF... ALTHOUGH THE ECMWF IS A BIT FARTHER NORTH. OUR BOUNDARY LAYER FLOW WILL CONTINUE FROM THE NW WITH LEE TROUGHING HOLDING ON THROUGH THE CWA. WILL CONTINUE THE DRY FORECAST WITH CONSIDERABLE SUNSHINE AND CONTINUED BELOW NORMAL TEMPERATURES. -GIH && .AVIATION /19Z FRIDAY THROUGH WEDNESDAY/... AS OF 140 PM... SNOW SHOWERS RAPIDLY DECREASING AND WILL END BY MID AFTERNOON. VFR CEILINGS WILL BECOME SCATTERED CLOUDS JUST BEFORE SUNSET. SUSTAINED WINDS 15 TO 20 MPH WITH GUSTS TO 35 MPH WILL END JUST BEFORE SUNSET AS WELL...FALLING TO NORTHWEST AT 10 KNOTS OR LESS. NORTHWEST WINDS AT 10 KNOTS SATURDAY MORNING WITH SCATTERED CUMULUS NEAR 5000 FEET DEVELOPING BY LATE MORNING. AN APPROACHING FRONT WILL BRING RAIN AND MVFR CEILINGS AND VISIBILITIES TO THE WEST SOMETIME MONDAY...SPREADING EAST DURING THE DAY AND INTO MONDAY NIGHT. SOME IFR CEILINGS IN PRECIPITATION. OTHERWISE VFR CONDITIONS ARE FORECAST. && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...VINCENT NEAR TERM...VINCENT SHORT TERM...HARTFIELD LONG TERM...HARTFIELD nc AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE RALEIGH NC 1206 PM EST FRI NOV 21 2008 .SYNOPSIS... BLUSTERY WINDS FROM THE NORTHWEST BEHIND THE RECENT COLD FRONTAL PASSAGE WILL USHER IN ANOTHER ROUND OF VERY COLD AIR. COLDER THAN NORMAL TEMPERATURES WILL CONTINUE THROUGH SUNDAY. && .NEAR TERM /THROUGH TONIGHT/... AS OF 1200 PM FRIDAY... SFC ANALYSIS THIS AFTERNOON SHOWED A 1010 MB LOW ABOUT 100 MILES EAST OF CAPE FEAR NC. STRONG (1040 MB) HIGH PRESSURE WAS CENTERED OVER EASTERN KS/OK AND MO/AR. THE 12Z GSO SOUNDING WAS QUITE COLD...WITH VERY STEEP (DRY ADIABATIC) LAPSE RATES FROM THE SFC THROUGH 750MB AND A 1000-850MB THICKNESS OF 1286M. ALOFT...AS OF 17Z THE LATEST RUC FCST DATA AND WV IMAGERY SHOW THE POTENT H5 SHORTWAVE BEGINNING TO ASSUME A NEUTRAL OR SLIGHTLY NEGATIVE TILT AS IT BEGINS TO CROSS CENTRAL NC. REST OF THIS AFTERNOON: FORECAST PRIMARILY ON TRACK WITH A SLIGHT CHANCE OF SNOW SHOWERS THROUGH ROUGHLY 2-3 PM THIS AFTERNOON ALONG/EAST OF THE TRIANGLE. CURRENT RADAR IMAGERY SHOWS SCATTERED PRECIP ECHOES JUST NORTH OF THE TRIANGLE INTO THE NORTHEAST COASTAL PLAIN. THESE CONVECTIVE SNOW SHOWERS HAVE DEVELOPED IN RESPONSE TO LINGERING LOW LEVEL MOISTURE...STEEP LOW LEVEL LAPSE RATES (ALLOWING MARGINAL INSTABILITY) AND UPPER LEVEL FORCING ASSOC/W THE POTENT SHORTWAVE BEGINNING TO GO NEUTRAL OR NEGATIVE TILT AS IT CROSSES CENTRAL NC. THE BEST CHANCE FOR SNOW SHOWER ACTIVITY WILL PROBABLY REMAIN IN FAR EASTERN NC THIS AFTERNOON WHERE UPPER LEVEL LIFT WILL REMAIN FAVORABLE LATER INTO THE AFTERNOON HOURS...ALTHOUGH WITH A BOUNDARY LAYER PROGRESSIVELY DRYING THROUGH THE DAY...WHETHER OR NOT ANYTHING ACTUALLY MAKES IT TO THE GROUND IS A VALID CONCERN. WILL LEAVE A SLIGHT CHANCE FLURRIES OR A BRIEF/LIGHT SNOW SHOWER IN THE FCST FROM THE TRIANGLE NORTHEAST TO RZZ SOUTH TO GSB THROUGH 2-3 PM (AT LATEST) THIS AFTERNOON. EXPECTED PTYPE SHOULD BE ALL SNOW...SINCE ANYTHING THAT IS HEAVY ENOUGH TO REACH THE GROUND SHOULD ALSO ALLOW ENOUGH EVAP COOLING / MELTING TO KEEP THERMAL PROFILES IN THE LOWEST 500-1500 FT NEAR FREEZING. WITH TEMPERATURES HOLDING IN THE MID/UPPER 30S TO LOWER 40S...AND A NORTHWEST WIND OF 15-20 MPH WITH GUSTS UP TO 30 MPH (BASED ON FCST SOUNDINGS SHOWING 25-30 KTS IN THE MIXED LAYER)... IT WILL BE QUITE CHILLY/BLUSTERY OUTSIDE FOR THE REMAINDER OF THIS AFTERNOON...ESPECIALLY AS WE GET CLOSE TO SUNSET AND TEMPS BEGIN TO PLUMMET. TONIGHT: *VERY* COLD CONDITIONS EXPECTED TONIGHT. GIVEN A RATHER TIGHT PRESSURE GRADIENT THIS EVENING...A NORTHWEST BREEZE WILL LIKELY CONTINUE FOR SEVERAL HOURS AFTER SUNSET AS TEMPERATURES BEGIN TO PLUMMET INTO THE LOWER 30S AND UPPER 20S. THIS WILL ALLOW WIND CHILL VALUES TO DROP INTO THE TEENS TO LOWER 20S LATER THIS EVENING. WINDS SHOULD BEGIN TO SUBSIDE BY OR SHORTLY AFTER MIDNIGHT FROM WEST TO EAST AS THE HIGH PRESSURE CENTER CURRENTLY OVER THE LOWER MIDWEST APPROACHES THE SOUTHERN APPALACHIANS AND THE GRADIENT BEGINS TO RELAX. CLEAR SKIES SHOULD BE THE RULE WITH STRONG SUBSIDENCE ACROSS CENTRAL NC BEHIND THE DEPARTING UPPER LEVEL WAVE. WILL FCST LOW TEMPS CLOSE TO MOS GUIDANCE...RANGING FROM 19-24F ACROSS THE AREA. THE RECORD LOW TEMPERATURE FOR RDU (23F SET IN 1987) COULD EASILY BE TIED OR BROKEN TONIGHT. -VINCENT && .SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/... AS OF 325 AM FRIDAY... FOR SATURDAY/SATURDAY NIGHT: THE SURFACE HIGH SETTLES OVERHEAD AND THE 850 MB ANTICYCLONE DRIFTS OVERHEAD DURING THIS PERIOD. BUT FARTHER ALOFT... WHAT IS NOW A STRONG LOW PUSHING THROUGH THE INTERIOR PACIFIC NORTHWEST DIVES QUICKLY TO THE ESE... DAMPENING INTO AN OPEN WAVE AS IT APPROACHES NC. BUT NEVERTHELESS THIS WAVE REMAINS OF RESPECTABLE STRENGTH AND SHOULD STILL BRING IN APPRECIABLE MID AND HIGH CLOUDINESS SPREADING INTO NC SATURDAY AFTERNOON FROM THE NW. NAM/GFS FORECAST SOUNDINGS ARE IN GOOD AGREEMENT ON THIS. HAVE RAISED SKY COVER... STARTING THE INCREASE IN THE LATE MORNING. THICKNESSES START TO REBOUND AS THE 850 MB WARM FRONT HEADS TO OUR NE AND HIGHS SHOULD BE A DEGREE OR TWO WARMER... 42-46... HARDLY NOTICEABLE THOUGH GIVEN THE FRIGID START TO THE DAY. CLOUD COVER SHOULD DECREASE LATE SATURDAY NIGHT AS THE CLIPPER SHORTWAVE TROUGH EXITS. FORECAST LOWS IN THE LOW-MID 20S STILL LOOK GOOD. FOR SUNDAY/SUNDAY NIGHT: QUIET WEATHER FOR SUNDAY WITH SURFACE HIGH PRESSURE OVER THE EASTERN CAROLINAS AND BROAD (BUT WEAK) RIDGING IN THE MID LEVELS. THICKNESSES RISE INTO THE 1290-1300 METER RANGE... STILL WELL BELOW NORMAL HOWEVER... AND WE SHOULD SEE HIGHS STILL ABOUT 1-2 CATEGORIES BELOW NORMAL... 52-57. OUR NEXT WEATHER SYSTEM OF INTEREST... A POLAR VORTEX... DROPS INTO THE UPPER MIDWEST SUNDAY NIGHT... AND MID LEVEL FLOW INTO THE APPALACHIANS STARTS TO BECOME CYCLONIC AND STRENGTHENS... AS THE SURFACE HIGHS SHIFTS OFFSHORE. WE SHOULD SEE INCREASING HIGH CLOUDS THROUGH THE NIGHT BUT THIS SHOULD HAVE LITTLE IMPACT ON RADIATIONAL COOLING. EXPECT LOWS OF 28-32. -GIH && .LONG TERM /MONDAY THROUGH THURSDAY/... AS OF 455 AM FRIDAY... FOR MONDAY THROUGH TUESDAY: A COLD MID LEVEL VORTEX IS EXPECTED TO DROP SOUTHEAST ACROSS THE GREAT LAKES REGION DURING THIS PERIOD. THE LATEST GFS AND ECMWF ARE IN GOOD AGREEMENT ON A FASTER ARRIVAL OF THE NEXT COLD FRONT AS COMPARED TO YESTERDAY`S GUIDANCE... AND HAVE HASTENED THE CLOUD COVER INCREASE AND RAISED POPS MONDAY AFTERNOON TO HIGH CHANCES IN THE NW CWA... TAPERING TO SLIGHT CHANCE IN THE SOUTHEAST. CHANCE POPS WILL BE CONTINUED THROUGH MONDAY NIGHT AS THE COLD FRONT SWEEPS RAPIDLY EAST. THE FRONT SHOULD BE WELL OFF THE COAST BY TUESDAY MORNING... AND ONLY A SLIGHT CHANCE EAST OF I-95 IS EXPECTED EARLY TUESDAY MORNING. EXPECT CLEARING FROM THE WEST BY MIDDAY TUESDAY. HIGHS 55-62 MONDAY WITH THICKNESSES JUST 10-15 M BELOW NORMAL. HIGHS TUESDAY 52-57... A MUCH LESS MODEST COOLING THAN WE`VE SEEN WITH THESE RECENT COLD FRONT PASSAGES... AS THE INCOMING SURFACE AIR MASS HAS ITS SOURCE IN THE PACIFIC AND ROCKIES RATHER THAN CANADA. MORNING LOWS 37-43. FOR WEDNESDAY THROUGH THANKSGIVING DAY: STILL LOOKS QUIET AND COOL IN CENTRAL NC. THE MID LEVEL VORTEX SITS AND SPINS OVER THE INTERIOR NORTHEAST ACCORDING TO THE LATEST GFS AND ECMWF... ALTHOUGH THE ECMWF IS A BIT FARTHER NORTH. OUR BOUNDARY LAYER FLOW WILL CONTINUE FROM THE NW WITH LEE TROUGHING HOLDING ON THROUGH THE CWA. WILL CONTINUE THE DRY FORECAST WITH CONSIDERABLE SUNSHINE AND CONTINUED BELOW NORMAL TEMPERATURES. -GIH && .AVIATION /12Z FRIDAY THROUGH TUESDAY/... AS OF 740 AM FRIDAY... THE BAND OF LIGHT SNOW AND ASSOCIATED MVFR TO IFR CONDITIONS WILL CONTINUE TO PIVOT EASTWARD THROUGH LATE MORNING... ENDING AT RDU BY 13-14Z AND FAY AND RWI BETWEEN 15 AND 16Z. VFR CONDITIONS FOR THE REMAINDER OF TODAY AND TONIGHT... WITH JUST SOME 4 TO 6 THSD FT SCATTERED CUMULUS OR STRATOCUMULUS... MAINLY THIS AFTERNOON. THE MAIN AVIATION CONCERN FOR TODAY WILL BECOME 15-20 KNOT SUSTAINED NORTHWESTERLY WINDS WITH FREQUENT GUSTS BETWEEN 22 AND 28 KTS. THE WINDS WILL GRADUALLY DIE OFF TO LESS THAN 10 KNOTS AND BACK TO A MORE WEST NORTHWESTERLY COMPONENT AFTER SUNSET. ASIDE FROM A CHANCE OF LIGHT RAIN SHOWERS AND SUB-VFR CONDITIONS ASSOCIATED WITH THE PASSAGE OF THE NEXT STORM SYSTEM MONDAY AND MONDAY NIGHT... VFR CONDITIONS ARE EXPECTED THROUGH TUESDAY. && .CLIMATE... RECORD LOWS FOR SATURDAY (NOVEMBER 22): RDU....23 (1987) GSO....17 (2000) && $$ SYNOPSIS...VINCENT NEAR TERM...VINCENT SHORT TERM...HARTFIELD LONG TERM...HARTFIELD AVIATION...MWS CLIMATE...HARTFIELD nc AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE LUBBOCK TX 1145 AM CST FRI NOV 21 2008 .AVIATION... EXPECT VFR CONDITIONS WITH CLEAR SKIES TO PREVAIL THROUGH THE PERIOD WITH LIGHT SOUTH WINDS INCREASING TO AROUND 15 KTS THIS AFTERNOON. A DEVELOPING LEE SIDE LOW ACROSS SOUTHEAST COLORADO WILL THEN VEER THESE WINDS MORE SOUTHWESTERLY BY SATURDAY. && .PREV DISCUSSION... /ISSUED 536 AM CST FRI NOV 21 2008/ AVIATION... VFR CONDITIONS TO CONTINUE NEXT 24 HOURS. LIGHT NORTHEAST WINDS TO VEER TO THE SOUTH AND INCREASE DURING THE DAY AS UPPER LEVEL DISTURBANCE MOVES INTO THE NORTHERN PLAINS TODAY INDUCING A LEE SIDE LOW AT THE SURFACE OVER SOUTHEAST COLORADO. PREV DISCUSSION... /ISSUED 415 AM CST FRI NOV 21 2008/ SHORT TERM... RATHER BENIGN WEATHER FOR THE SHORT TERM. BOTH RUC AND NAM MODELS IN GOOD AGREEMENT THAT LOW CLOUDS NEAR THE NEW MEXICO BORDER WILL REMAIN THERE AND GRADUALLY DISSIPATE THIS MORNING. SHORTWAVE CURRENTLY SEEN ON WATER VAPOR...MOVING INTO WESTERN MONTANA TO CONTINUE MOVING EAST INTO SOUTH DAKOTA BY THIS EVENING THEN INTO IOWA BY SATURDAY MORNING. THIS FEATURE TO AID IN DEVELOPING A LEE SIDE LOW OVER SOUTHEAST COLORADO. THIS WITH SURFACE HIGH ALSO MOVING TO THE EAST WILL HAVE WINDS VEER AROUND TO THE SOUTH LATER THIS MORNING. WIND WILL ALSO PICK UP AND BECOME A BIT GUSTY AS SURFACE GRADIENT TIGHTENS. TEMPERATURES TO REMAIN ON THE COOL SIDE WITH WARMER TEMPERATURES OVER NORTHWEST ZONES WHERE WINDS EXPECTED TO BE MORE SOUTHWEST AND STRONGER. ALTHOUGH SKIES EXPECTED TO BE CLEAR AGAIN TONIGHT...WITH SOUTHERLY AND SLIGHTLY STRONGER WINDS .LOWS TO BE SLIGHTLY WARMER THEN THIS MORNING. LONG TERM... MODERATING TREND WILL CONTINUE THROUGH THE WEEKEND AS FLAT RIDGE ALOFT PROMOTES SURFACE LOW PRESSURE OVER SOUTHERN HIGH PLAINS. DOWNSLOPE WARMING SHOULD INCREASE SUNDAY AS PRESSURE FALLS FURTHER IN RESPONSE TO THE NEXT CLIPPER-TYPE LOW DIVING SOUTHEAST THROUGH ALBERTA. THIS SYSTEM WILL CROSS THE GREAT LAKES MONDAY PULLING THE NEXT SURFACE COLD FRONT SOUTHWARD THR0UGH THE AREA PRIOR TO DAYBREAK MONDAY. CURRENT EXPECTATIONS CALL FOR MODEST SURFACE PRESSURE RISES EARLY MONDAY MORNING RESULTING IN BREEZY POST FRONTAL WINDS. TEMPERATURES MONDAY ALSO ANTICIPATED TO FALL ONLY MODESTLY. CONTINENTAL PATTERN IS THEN EXPECTED TO BEGIN AMPLIFICATION AS A SERIES OF PACIFIC LOWS DIG ONTO THE CALIFORNIA COAST SENDING HEIGHTS BACK UP ACROSS SOUTHERN HIGH PLAINS THROUGH MID-WEEK. PATTERN SHOULD REMAIN PROGRESSIVE INITIALLY WITH FLOW ALOFT BECOMING SOUTHWESTERLY ON WEDNESDAY. MOISTURE LEVELS SHOULD IMPROVE WITH CURRENT LONG RANGE GUIDANCE SUGGESTING ENOUGH MOISTENING FOR PRECIPITATION CONSIDERATION AS EARLY AS WEDNESDAY AS INITIAL DISTURBANCE SHEARS NORTHEAST ACROSS ROCKIES FROM THE CALIFORNIA COAST. TO US THIS WAVE LOOKS TOO OPEN WHILE ATMOSPHERE LIKELY WILL NEED MORE MOISTURE DEEPENING AS WELL. ANOTHER STRONGER THOUGH STILL SOMEWHAT OPEN WAVE IS EXPECTED TO PROGRESS FROM THE WEST COAST OVER SOUTHERN PLAINS THANKSGIVING DAY. THIS WAVE HAS SHOWN GOOD CONTINUITY ON ENSEMBLE RUNS FOR THE PAST WEEK...AND AT THIS POINT HAS CREDIBILITY ENOUGH TO WARRANT INITIAL LOW END SHOWER CHANCES AS MOISTURE EXPECTED TO BE ADEQUATE AS WELL. TEMPERATURE PROFILE CLEARLY FAVORS LIQUID THIS FAR OUT AND ALSO SUGGESTS PRECIPITATION MAY BE CONVECTIVE. THIS WAVE SHOULD LIFT TO THE EAST-NORTHEAST THURSDAY NIGHT OR EARLY FRIDAY... WITH MODEL TIMING ISSUES FACTORING INTO UNCERTAINTY. MCQUEEN && .PRELIMINARY POINT TEMPS/POPS... FRIONA 46 26 62 31 69 / 0 0 0 0 0 TULIA 45 26 61 31 67 / 0 0 0 0 0 PLAINVIEW 45 27 61 32 69 / 0 0 0 0 0 LEVELLAND 45 28 62 32 70 / 0 0 0 0 0 LUBBOCK 46 29 61 35 71 / 0 0 0 0 0 DENVER CITY 46 30 64 35 72 / 0 0 0 0 0 BROWNFIELD 47 30 63 33 72 / 0 0 0 0 0 CHILDRESS 48 29 59 35 69 / 0 0 0 0 0 SPUR 48 31 62 35 70 / 0 0 0 0 0 ASPERMONT 50 31 63 40 71 / 0 0 0 0 0 && .LUB WATCHES/WARNINGS/ADVISORIES... NONE. && $$ 93/08 tx