AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GRAND JUNCTION CO 837 PM MDT SUN APR 20 2008 .UPDATE...COLD FRONT MAKING ITS WAY ACROSS THE NORTHERN HALF OF THE FORECAST AREA THIS EVENING. PLENTY OF BLOWING DUST MOVING IN BEHIND THE FRONT REMAINS SUSPENDED IN THE LOWER LEVELS...AND HAS BROUGHT SOME RESTRICTION TO VISIBILITIES ALONG THE INTERSTATE 70 CORRIDOR. AS THE WINDS CONTINUE TO DECREASE...THE DUST WILL SETTLE OUT AND VISIBILITIES WILL START TO IMPROVE. WITH THE DIMINISHING WINDS...WILL GO AHEAD AND LET THE RED FLAG WARNING AND THE WIND ADVISORY FOR THIS EVENING EXPIRE AT 9 PM MDT. WILL BE ISSUING TWO STATEMENTS...ONE CLEARING THIS EVENINGS HIGHLIGHTS AND A SECOND TO REMOVE THE EXPIRATION MESSAGES ABOUT 30 MINUTES LATER. MONDAY HIGHLIGHTS STILL ON TARGET...DETAILS BELOW. && .SHORT TERM...TONIGHT THROUGH TUESDAY... SURFACE OBSERVATIONS EARLY THIS AFTERNOON AND RUC DATA SHOW THE COLD FRONT THROUGH VERNAL AND PRICE...BUT JUST WEST OF CANYONLANDS AND HANKSVILLE. THE NORTHERN PORTION OF THE FRONT WILL CONTINUE EAST AND MOVE THROUGH NORTHWEST COLORADO THIS EVENING. IT SHOULD REACH ROUTT COUNTY BY ABOUT 8 PM MDT. THE SOUTHERN PORTION...SOUTH OF ABOUT INTERSTATE 70...WILL CONTINUE LAGGING BACK TO THE SOUTHWEST AND SLOW ITS EASTERLY PROGRESS. EXPECT THE FRONT TO HANGUP LATE TONIGHT SOMEWHERE BETWEEN GRAND JUNCTION AND MONTROSE...AND STAY NORTH OF MONTICELLO. THE STRONG SOUTHWEST WINDS AND HEIGHTENED FIRE WEATHER CONCERNS WILL CONTINUE UNTIL THE WINDS DIMINISH ABOUT 9 PM. THERE IS NOT MUCH IN THE WAY OF CLOUD COVER WITH THIS SYSTEM...SO HAVE DECREASED CLOUDS AND POPS SIGNIFICANTLY FOR TONIGHT AND MONDAY. MONDAY THROUGH TUESDAY...WINDS ALOFT WILL SLOWLY DECREASE SO ANOTHER WIDESPREAD WIND ADVISORY WAS NOT ISSUED. INSTEAD...BELIEVE WINDS WILL BE STRONG ENOUGH FOR AN ADVISORY ONLY IN THE I-70 CORRIDOR EAST OF GRAND JUNCTION TO EDWARDS...CO ZONES 7 AND 8...MONDAY AFTERNOON AND EARLY EVENING. THE COLD FRONT WILL BE ABOUT PARALLEL TO THE WESTERLY FLOW AND WILL SLOUGH A BIT FURTHER SOUTH. MONDAY SHOULD BE A BIT COOLER AS A RESULT IN ALL BUT THE MOST SOUTHERN ZONES. ON TUESDAY THE FRONT SHOULD WAVE BACK TO THE NORTH AND AN POORLY DEFINED WARM FRONT. THIS SHOULD CONTINUE THE DECREASING WIND TREND...WHILE TEMPS INCREASE AGAIN WITH HUMIDITY STAYING LOW. .LONG TERM...TUESDAY NIGHT THROUGH SUNDAY... CONSISTENCY REMAINS GOOD AS LONG AS ONE THROWS OUT THE 06Z GFS BEYOND MIDWEEK. THERE STILL ARE A FEW MINOR TIMING DIFFERENCES...WITH THE MIDWEEK TROUGH PASSAGE AND COLD FRONT WAITING FOR THU AFTERNOON. THE 12Z CAME BACK IN LINE WITH THE 00Z ECMWF AND GFS RUNS IN BRINGING A FLAT RIDGE OVER THE WEST FOR THE LATTER HALF OF THE PERIOD. SOUTHWEST WINDS WILL AGAIN PICK UP WED AFTERNOON AS THE TROUGH STRENGTHENS TO OUR WEST. HOWEVER MODELS HAVE TRENDED MORE NORTHERLY WITH ITS TRACK ON THUR...AND WEAKER WITH ITS ASSOCIATED COLD FRONT. SO TWEAKED THE ALREADY LOW POPS DOWNWARDS...AND THURSDAYS TEMPERATURES UPWARDS. BEYOND THURSDAY...A WARMING TREND IS EXPECTED AS A RIDGE BUILDS OVER THE WEST COAST THEN SHIFTS EASTWARD THROUGH THE REMAINDER OF THE PERIOD. && .AVIATION... VFR WILL CONTINUE THROUGH MONDAY. HOWEVER...WINDY CONDITIONS WITH AFTERNOON GUSTS REACHING 40 KNOTS OVER THE RIDGES WILL BE COMMON AND CAUSE WIDESPREAD TURBULENCE AND MOUNTAIN WAVES OVER AND IN THE LEE OF RIDGES. && .FIRE WEATHER (FROM SATURDAY AFTERNOON DISCUSSION)... A COLD FRONT SWEEPS ACROSS THE NORTH THIS EVENING AND BECOMES STATIONARY NEAR THE I-70 CORRIDOR. THIS WILL USHER IN A COOLER AIRMASS NORTH OF THE ROAN/TAVAPUTS FOR INCREASED RH MONDAY AFTERNOON. SOUTH OF THE FRONT...SURFACE-BASED INVERSIONS WILL SET UP QUICKLY AFTER SUNSET. BUT MIXING WILL BRING RED FLAG WARNING CONDITIONS AGAIN LATE MONDAY MORNING. AFTERNOON HUMIDITIES OF 8-15 PCT WITH WIND GUSTS 35-45 MPH IN THESE AREAS WILL AGAIN CREATE DANGEROUS FIRE CONDITIONS. COORDINATION WITH LAND MGMT AGENCIES INDICATE THE MAIN CONCERN IS THE BURNING OF DITCHES OF AGRICULTURAL FIELDS...WHERE DEAD/DRY VEGETATION WILL FUEL RAPID FIRE GROWTH. WINDY CONDITIONS ARE EXPECTED TO CONTINUE THROUGH THURSDAY...BUT COOLER TEMPS FORECAST SHOULD RESULT IN SOMEWHAT HIGHER HUMIDITIES. && .GJT WATCHES/WARNINGS/ADVISORIES... .CO...RED FLAG WARNING IN EFFECT FROM 11 AM UNTIL 7 PM MDT MONDAY FOR FIRE WEATHER ZONES 203/205/207 BELOW 6500 FEET. WIND ADVISORY IN EFFECT MONDAY FROM 11 AM 7 PM MDT...FOR THE INTERSTATE 70 CORRIDOR FROM CAMEO TO EDWARDS...ZONES 7 AND 8. .UT...NONE. $$ UPDATE.........JDC SHORT TERM.....CJC LONG TERM......ELH AVIATION.......CJC FIRE WEATHER...JOE/JDC co AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DENVER CO 300 PM MDT SUN APR 20 2008 .SHORT TERM...FAIRLY STRONG SOUTHWEST GRADIENT ACROSS COLORADO AT PRESENT DUE TO UPPER TROUGH OVER PACIFIC NORTHWEST. GUSTY SOUTHWEST WINDS OCCURRING OVER CWA DUE TO GOOD MIXING. HUMIDITY READINGS HAVE BOTTOMED OUT AROUND 10 PERCENT. FIRE WEATHER CONCERNS REMAIN CRITICAL OVER THE PLAINS. RUC CONTINUES THE GUSTY WINDS THROUGH AT LEAST 02Z...SO RED FLAG WARNING WILL CONTINUE. CONDITIONS SHOULD IMPROVE AT THAT TIME AS HUMIDITY LEVELS BEGIN TO INCREASE. MODELS CONTINUE TO SHOW COLD FRONT MOVING ACROSS MOUNTAINS THIS EVENING...THEN ONTO THE PLAINS AROUND 06Z. SHOULD SEE WINDS BECOME WESTERLY ACROSS THE MOUNTAINS AFTER FRONT PASSES THROUGH. MODEL CROSS SECTIONS INDICATING LITTLE IF ANY MOISTURE THROUGH ABOUT 12Z. WILL DROP THE LOW POPS FOR THE MOUNTAINS TONIGHT. AS FOR THE PLAINS...WINDS BECOME NORTHERLY. NO POPS AS AIRMASS DRY. ON MONDAY...MODELS CONTINUE TO SHOW WEAK WAVE MOVING ACROSS AREA AS NOTED BY AREA OF QG ASCENT. SOME MID LEVEL ASSOCIATED WITH THIS WAVE. COULD SEE SOME PRECIP DEVELOP ACROSS MOUNTAINS...CURRENT LOW POPS SEEM REASONABLE AT THIS POINT. FOR THE PLAINS...SURFACE FLOW EXPECTED TO BECOME SOUTHEAST BY AFTERNOON...WHICH COULD LEAD TO SOME WEAK CONVERGENCE ALONG FOOTHILLS. WITH WEAK ASCENT AND LAPSE RATES AROUND 8 C/KM...CAN`T RULE OUT THE POSSIBILITY OF A FEW STORMS DEVELOPING...THOUGH FORECAST CAPES ARE MINIMAL. CURRENT FORECAST ALREADY HAS A SLIGHT CHANCE OF STORMS FOR FOOTHILLS AND ADJACENT PLAINS FOR THE AFTERNOON...WILL CONTINUE. NOT MUCH IN THE WAY OF LOW LEVEL MOISTURE...SO ANY PRECIPITATION WILL BE LIGHT. COULD BE SOME GUSTY DOWNDRAFTS WITH THE STORMS. TEMPERATURE AND THICKNESS PROGS SHOW TEMPERATURES ABOUT 10 DEGREES COOLER THAN TODAY`S READINGS. CURRENT TEMPERATURE GRIDS SEEM ON TRACK. NOT EXPECTING ANY FIRE WEATHER CONCERNS AS WINDS AND HUMIDITY SHOULD BE BELOW CRITICAL LEVELS. .LONG TERM...MODELS HAVE STRONG WEST-NORTHWESTERLY FLOW ALOFT OVER THE FORECAST AREA MONDAY NIGHT...WITH A JET MAX TO OUR IMMEDIATE NORTH. ON TUESDAY THE UPPER LEVEL FLOW DECREASES QUITE A BIT AND BECOMES MORE SOUTHWESTERLY. THIS CONTINUES INTO EARLY WEDNESDAY. LATER WEDNESDAY...THE FLOW INCREASES A BIT AND BECOMES MORE WESTERLY. DOWNWARD SYNOPTIC SCALE ENERGY IS PROGGED FOR THE FORECAST AREA MONDAY NIGHT AND TUESDAY. FROM TUESDAY NIGHT THROUGH WEDNESDAY EVENING...WEAK UPWARD MOTION IS PROGGED FOR THE FORECAST AREA. THE BOUNDARY LAYER FLOW IS FAIRLY BENIGN MONDAY NIGHT THROUGH TUESDAY NIGHT. BY WEDNESDAY...LOWER PRESSURE EAST OF THE MOUNTAINS INDICATES SOME SOUTHWESTERLY DOWNSLOPING FLOW FOR THE FOOTHILLS AND PLAINS. FOR MOISTURE...THERE IS A BIT IN THE MID AND UPPER LEVELS MONDAY NIGHT THROUGH WEDNESDAY. THERE IS A BIT OF LOW LEVEL MOISTURE OVER THE PLAINS WEDNESDAY. THERE IS A THETA-E AXIS ACROSS THE EASTERN PLAINS WEDNESDAY AFTERNOON. THE STEEPEST LAPSE RATES ARE PROGGED ON WEDNESDAY. FORECAST SOUNDINGS SHOW A TINY BIT OF CAPE MONDAY EVENING OVER THE CENTRAL FORECAST AREA. THERE IS ALSO SOME LIMITED CAPE OVER THE MOUNTAINS AND FOOTHILLS LATE DAY WEDNESDAY...WITH FAIRLY DECENT CAPE VALUES OVER THE FAR EASTERN BORDER WEDNESDAY AFTERNOON. NO POPS MONDAY NIGHT THROUGH WEDNESDAY MORNING JUST NOT ENOUGH MOISTURE. WILL GO 10-20% WEDNESDAY AFTERNOON INTO THE EVENING WITH THUNDER MENTIONED AS WELL. FOR TEMPERATURES... TUESDAY`S HIGHS ARE 3-4 C WARMER THAN MONDAY`S. WEDNESDAY`S HIGHS ARE 2-4 C WARMER THAN TUESDAY`S. FOR THE LATER DAYS...THURSDAY THROUGH SUNDAY...MODELS SHOW AN UPPER TROUGH PUSH ACROSS THURSDAY INTO EARLY FRIDAY. THERE IS NORTHWESTERLY FLOW ALOFT FRIDAY. THEN AN UPPER RIDGE FOR THE WEEKEND. WILL DRY THURSDAY OUT A BIT ON THE GRIDS AND LEAVE THE REST OF THE POPS WITH THE TROUGH AS IS. FRIDAY IS THE ONLY COOL DAY. WILL WARM THURSDAY UP AND KEEP READINGS A BIT A ABOVE NORMALS FOR THE LAST DAY...SUNDAY. && .AVIATION...WEST SOUTHWEST WINDS OF 15-25 KTS WITH SOME GUSTS TO 30 KTS TO CONTINUE THROUGH ABOUT 03Z BEFORE DECREASING. A COLD FRONT WILL MOVE ACROSS THE AREA AROUND 06Z WITH WINDS BECOMING NORTHERLY. FRONT WILL BE DRY...SO VFR CONDITIONS EXPECTED WITH NO PRECIP. A FEW HIGH BASED STORMS COULD DEVELOP AFTER 18Z ALONG FOOTHILLS... SLOWLY DRIFTING ACROSS ADJACENT PLAINS BETWEEN 21Z AND 00Z. GUSTY OUTFLOW WINDS TO AROUND 30KTS POSSIBLE FROM THE STORMS...WHICH COULD AFFECT AREA AIRPORTS. ANY AREA PRECIPITATION WILL BE LIGHT. && .BOU WATCHES/WARNINGS/ADVISORIES...RED FLAG WARNING UNTIL 8 PM FOR NORTHEAST PLAINS...COZ238>251 FOR GUSTY WIND AND LOW HUMIDITY. && $$ D-L/RJK co AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GRAND JUNCTION CO 242 PM MDT SUN APR 20 2008 .SHORT TERM...TONIGHT THROUGH TUESDAY... SURFACE OBSERVATIONS AND RUC SHOW THE COLD FRONT THROUGH VERNAL AND PRICE...BUT JUST WEST OF CANYONLANDS AND HANKSVILLE. THE NORTHERN PORTION OF THE FRONT WILL CONTINUE EAST AND MOVE THROUGH NORTHWEST COLORADO THIS EVENING. IT SHOULD REACH ROUTT COUNTY BY ABOUT 8 PM MDT. THE SOUTHERN PORTION...SOUTH OF ABOUT INTERSTATE 70...WILL CONTINUE LAGGING BACK TO THE SOUTHWEST AND SLOW ITS EASTERLY PROGRESS. EXPECT THE FRONT TO HANGUP LATE TONIGHT SOMEWHERE BETWEEN GRAND JUNCTION AND MONTROSE...AND STAY NORTH OF MONTICELLO. THE STRONG SOUTHWEST WINDS AND HEIGHTENED FIRE WEATHER CONCERNS WILL CONTINUE UNTIL THE WINDS DIMINISH ABOUT 9 PM. THERE IS NOT MUCH IN THE WAY OF CLOUD COVER WITH THIS SYSTEM...SO HAVE DECREASED CLOUDS AND POPS SIGNIFICANTLY FOR TONIGHT AND MONDAY. MONDAY THROUGH TUESDAY...WINDS ALOFT WILL SLOWLY DECREASE SO ANOTHER WIDESPREAD WIND ADVISORY WAS NOT ISSUED. INSTEAD...BELIEVE WINDS WILL BE STRONG ENOUGH FOR AN ADVISORY ONLY IN THE I-70 CORRIDOR EAST OF GRAND JUNCTION TO EDWARDS...CO ZONES 7 AND 8...MONDAY AFTERNOON AND EARLY EVENING. THE COLD FRONT WILL BE ABOUT PARALLEL TO THE WESTERLY FLOW AND WILL SLOUGH A BIT FURTHER SOUTH. MONDAY SHOULD BE A BIT COOLER AS A RESULT IN ALL BUT THE MOST SOUTHERN ZONES. ON TUESDAY THE FRONT SHOULD WAVE BACK TO THE NORTH AND AN POORLY DEFINED WARM FRONT. THIS SHOULD CONTINUE THE DECREASING WIND TREND...WHILE TEMPS INCREASE AGAIN WITH HUMIDITY STAYING LOW. .LONG TERM...TUESDAY NIGHT THROUGH SUNDAY... CONSISTENCY REMAINS GOOD AS LONG AS ONE THROWS OUT THE 06Z GFS BEYOND MIDWEEK. THERE STILL ARE A FEW MINOR TIMING DIFFERENCES...WITH THE MIDWEEK TROUGH PASSAGE AND COLD FRONT WAITING FOR THU AFTERNOON. THE 12Z CAME BACK IN LINE WITH THE 00Z ECMWF AND GFS RUNS IN BRINGING A FLAT RIDGE OVER THE WEST FOR THE LATTER HALF OF THE PERIOD. SOUTHWEST WINDS WILL AGAIN PICK UP WED AFTERNOON AS THE TROUGH STRENGTHENS TO OUR WEST. HOWEVER MODELS HAVE TRENDED MORE NORTHERLY WITH ITS TRACK ON THUR...AND WEAKER WITH ITS ASSOCIATED COLD FRONT. SO TWEAKED THE ALREADY LOW POPS DOWNWARDS...AND THURSDAYS TEMPERATURES UPWARDS. BEYOND THURSDAY...A WARMING TREND IS EXPECTED AS A RIDGE BUILDS OVER THE WEST COAST THEN SHIFTS EASTWARD THROUGH THE REMAINDER OF THE PERIOD. && .AVIATION... VFR WILL CONTINUE THROUGH MONDAY. HOWEVER...WINDY CONDITIONS WITH AFTERNOON GUSTS REACHING 40 KNOTS OVER THE RIDGES WILL BE COMMON AND CAUSE WIDESPREAD TURBULENCE AND MOUNTAIN WAVES OVER AND IN THE LEE OF RIDGES. && .FIRE WEATHER (FROM SATURDAY AFTERNOON DISCUSSION)... WIDESPREAD GUSTY SW GRADIENT WINDS AND LOW RH CONTINUE THIS AFTERNOON. THE COLD FRONT SWEEPS ACROSS THE NORTH THIS EVENING AND BECOMES STATIONARY NEAR THE I-70 CORRIDOR. THIS WILL USHER IN A COOLER AIRMASS NORTH OF THE ROAN/TAVAPUTS FOR INCREASED RH MONDAY AFTERNOON. SOUTH OF THE FRONT...SURFACE-BASED INVERSIONS WILL SET UP QUICKLY AFTER SUNSET. BUT MIXING WILL BRING RED FLAG WARNING CONDITIONS AGAIN LATE MONDAY MORNING. AFTERNOON HUMIDITIES OF 8-15 PCT WITH WIND GUSTS 35-45 MPH IN THESE AREAS WILL AGAIN CREATE DANGEROUS FIRE CONDITIONS. COORDINATION WITH LAND MGMT AGENCIES INDICATE THE MAIN CONCERN IS THE BURNING OF DITCHES OF AGRICULTURAL FIELDS...WHERE DEAD/DRY VEGETATION WILL FUEL RAPID FIRE GROWTH. WINDY CONDITIONS ARE EXPECTED TO CONTINUE THROUGH THURSDAY...BUT COOLER TEMPS FORECAST SHOULD RESULT IN SOMEWHAT HIGHER HUMIDITIES. && .GJT WATCHES/WARNINGS/ADVISORIES... .CO...RED FLAG WARNING IN EFFECT UNTIL 9 PM MDT TODAY FOR FIRE WEATHER ZONES 201/203/205/207 BELOW 6500 FEET. RED FLAG WARNING IN EFFECT FROM 11 AM UNTIL 7 PM MDT MONDAY FOR FIRE WEATHER ZONES 203/205/207 BELOW 6500 FEET. WIND ADVISORY IN EFFECT FOR ALL LOWER ELEVATIONS ZONES TODAY FROM NOON UNTIL 9 PM MDT...ZONES 1/2/6/7/8/11/14/20/ 21/22/23. WIND ADVISORY IN EFFECT MONDAY FROM 11 AM 7 PM MDT...FOR THE INTERSTATE 70 CORRIDOR FROM CAMEO TO EDWARDS...ZONES 7 AND 8. .UT...RED FLAG WARNING IN EFFECT UNTIL 9 PM MDT TODAY FOR FIRE WEATHER ZONE 443 BELOW 5500 FEET. WIND ADVISORY IN EFFECT FOR ALL LOWER ELEVATIONS ZONES TODAY FROM NOON UNTIL 9 PM MDT...ZONES 24/27/29/22. $$ SHORT TERM.....CJC LONG TERM......ELH AVIATION.......CJC FIRE WEATHER...JOE co AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DENVER CO 240 PM MDT SAT APR 19 2008 .SHORT TERM...UPPER TROUGH MOVING INTO GREAT BASIN IS INCREASING THE SOUTHWEST FLOW ALOFT OVER AREA. ACROSS PLAINS...SOUTHERLY WINDS HAVE DEVELOPED IN RESPONSE TO SURFACE HIGH OVER KANSAS...AND HAVE BECOME A BIT GUSTY AS THE STRONGER WINDS MIXED TO THE SURFACE. DEWPOINTS HAVE DROPPED INTO THE TEENS MOST AREAS OF THE PLAINS WITH HUMIDITY READINGS AROUND 15% OR LESS. LATEST RUC INDICATES LITTLE CHANGE IN CURRENT CONDITIONS THROUGH 00Z...WILL KEEP RED FLAG WARNING GOING TILL 02Z FOR PLAINS. AFTER THAT...SURFACE WINDS DECREASE A BIT WITH INCREASING DEWPOINTS AS LOW LEVEL MOISTURE GETS ADVECTED INTO AREA. AS FOR MOUNTAINS...GUSTY WINDS TO CONTINUE...ESPECIALLY OVER THE RIDGES. SOME HIGH LEVEL MOISTURE MOVES ACROSS AREA...NOT ENOUGH TO MAKE ANY IMPACT. ON SUNDAY...SOUTHWEST FLOW ALOFT WILL CONTINUE TO INCREASE AS TROUGH MOVES CLOSER TO COLORADO. MODEL CROSS SECTIONS CONTINUE TO SHOW A BATCH OF MID LEVEL MOISTURE MOVING INTO MOUNTAINS DURING THE AFTERNOON...APPEARS TO BE ASSOCIATED WITH A WEAK SHORTWAVE. MODELS SHOW SOME QG ASCENT OVER MOUNTAINS AT THAT TIME. WITH LAPSE RATES AROUND 8 C/KM...COULD SEE SOME AFTERNOON BUILDUPS. NOT EXPECTING ANY PRECIP AT THIS TIME...SO WILL KEEP POPS ZERO. MAIN CONCERN AGAIN WILL BE FIRE WEATHER ISSUES ACROSS PLAINS DURING AFTERNOON...AS GUSTY SOUTHWEST WINDS EXPECTED TO DEVELOP WITH RELATIVE HUMIDITY READINGS IN THE TEENS. TO AVOID ANY CONFUSION WITH CURRENT RED FLAG WARNING...WILL LET THE EVENING CREW HOIST THE HILIGHT FOR TOMORROW AFTER TODAY`S WARNING ENDS. GUIDANCE TEMPERATURES LOOK A BIT TOO COOL GIVEN THE INCREASE IN SOUTHWEST WINDS. CURRENT TEMPERATURE GRIDS SEEM MORE REASONABLE...WILL MAKE MINIMAL CHANGES. .LONG TERM...LARGE SCALE TROUGH OVER THE PACIFIC NORTHWEST WILL SPIT SOME ENERGY OUR WAY FROM TIME TO TIME EARLY IN THE PERIOD WITH MOST OF IT HEADING ACROSS WYOMING. EXACT TIMING OF THESE FEATURES IS LESS THAN EXACT BUT IT WOULD APPEAR THAT THE IMPACT ON OUR AREA WON/T BE TERRIBLY SIGNIFICANT...SLIGHT CHANCE OF SOME PRECIPITATION ...COOLER TEMPERATURES AND SOME INCREASE IN THE WINDS APPEARS TO BE ABOUT IT. THE COOLER TEMPERATURES AND ASSOCIATED HIGHER RELATIVE HUMIDITIES WILL ALLEVIATE THE FIRE WEATHER PROBLEMS THAT WE ARE PRESENTLY EXPERIENCING. TOWARDS MIDWEEK THE MODELS SUGGEST THAT A RIDGE MAY BUILD INTO THE PACIFIC NORTHWEST FORCING A STRONGER TROUGH ACROSS THE CENTRAL ROCKIES. HAVE MADE RELATIVELY MINOR CHANGES TO THE GRIDS IN THE LONGER TERM TO REFLECT THESE THOUGHTS. && .AVIATION...VFR CONDITIONS EXPECTED THROUGH SUNDAY. SOUTHERLY SURFACE GRADIENT ACROSS PLAINS TO WEAKEN AFTER 00Z WITH SURFACE WINDS DECREASING AND DRAINAGE PATTERN DEVELOPING. SOUTHWEST WINDS TO INCREASE AFTER 18Z...WITH SOME GUSTS TO 30 KTS EXPECTED AT THE LOCAL AIRPORTS. && .BOU WATCHES/WARNINGS/ADVISORIES...RED FLAG WARNING UNTIL 02Z FOR NORTHEAST PLAINS...COZ238>251. && $$ D-L/ET co AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE ALBANY NY 345 PM EDT SUN APR 20 2008 .SYNOPSIS... THE RIDGE OF HIGH PRESSURE WILL REMAIN IN CONTROL HEADING INTO THE NEW WEEK. HOWEVER...WITH COOLER AIR COMING OFF THE ATLANTIC...LOWER CLOUD COVER WILL IMPACT THE MIDDLE HUDSON VALLEY AND PORTIONS OF NORTHWEST CONNECTICUT. THE NEXT CHANCE FOR RAINFALL ARRIVES LATE WEDNESDAY WITH AN APPROACH OF A COLD FRONT. && .NEAR TERM /THROUGH TONIGHT/... SATELLITE PICTURES SHOW THE MARINE STRATUS SLOWING BUT SURELY ERODING AWAY FROM THE EAST IN OUR SOUTHERN AREAS. LATEST OBS STILL HAD KPOU CLOUDY BUT EVEN THERE...SOME SUNSHINE SHOULD BREAK OUT SOON. EVEN WITH LIMITED SUNSHINE...TEMPERATURES WILL REMAIN QUITE A BIT LOWER THAN THOSE OF YESTERDAY...MAINLY IN THE 60S. THE CUTOFF LOW...CENTERED OVER SW VA...CONTINUES TO SLOWLY "WOBBLE" TO THE ESE AND THE HEAVY SWATH OF RAIN ASSOCIATED WITH IT...SHOULD REMAIN TO OUR SOUTH. OVER THE REMAINDER OF THE COUNTY WARNING AREA (CWA)...NOTHING MORE THAN HIGH CLOUDS AND SOME HAZE WITH A GOOD DEAL OF SUNSHINE. TEMPERATURES ARE A BIT COOLER THAN YESTERDAY BUT NOT AS MUCH...TOPPING OUT IN THE 70S. TONIGHT...ONCE THE SUN GOES DOWN...THE STRATUS WILL LIKELY REFORM TO OUR SOUTH UNDERNEATH AN INCREASING AND LOWER INVERSION...AS THE MARINE AIR GETS TRAPPED UNDERNEATH IT. THE STRATUS MIGHT SNEAK A LITTLE FURTHER UP THE HUDSON VALLEY...BUT FOR NOW...BELIEVE IT WILL ONCE AGAIN STAY JUST SOUTH OF THE TRI-CITY AREA. THE MODEL SOUNDINGS DO INDICATE WHAT STRATUS CLOUDS THAT DO FORM... SHOULD BE VERY SHALLOW AND NOT THICK ENOUGH TO SUPPORT EVEN ANY DRIZZLE...SO LEFT IT OUT. WENT CLOSE TO MAV LOWS OVERNIGHT...EXCEPT A LITTLE HIGHER IN THE CAPITAL DISTRICT WHERE WE THINK A BREEZE MIGHT PERSIST A BIT LONGER MITIGATING A RADIATIONAL LOSS OF HEAT FLUX. && .SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/... TOMORROW...THE CUTOFF LOW IS FORECAST TO CONTINUE TO SLOWLY SINK SOUTHWARD BY BOTH THE 12Z NAM AND GFS MODELS. AT THE SAME TIME...HIGH PRESSURE ALOFT IS ACTUALLY FORECAST BY BOTH MODELS TO REBUILD OVER OUR CWA. THIS WILL INCREASE SUBSIDENCE ONCE AGAIN. THIS SUBSIDENCE IN CONJUNCTION WITH THE STRONG LATE APRIL SUNSHINE (HAVING THE SAME EQUIVALENT AS SUNSHINE IN LATE AUGUST)...SHOULD BE ENOUGH TO BURN OFF ANY LOW STRATUS CLOUDS...LEAVING ONLY SOME RESIDUAL HIGH AND MID LEVEL ONES...WHICH HAVE BLOWN OFF THE UPPER AIR LOW. H850 TEMPERATURES LOOK TO HOLD AROUND +8C. WITH GOOD MIXING...TEMPERATURES WILL TOP OUT WITHIN A FEW DEGREES OF 70 IN VALLEY LOCATIONS...AND 60S OVER THE HIGHER TERRAIN. WENT CLOSE TO MAV VALUES. VERY LITTLE LOOKS TO CHANGE IN TERMS OF THE SYNOPTIC SETUP AND SENSIBLE WEATHER THROUGH TUESDAY NIGHT. THE CUTOFF LO9W WILL CONTINUE TO VERY SLOW DRIFT SOUTH AND EAST...BY THIS POINT...OFF THE SOUTH CAROLINA COASTLINE. HIGH PRESSURE WILL REMAIN OVER OUR REGION BOTH AT THE SURFACE AND ALOFT WITH VERY LITTLE CHANGE IN TEMPERATURES THROUGH THE COLUMN. TEMPERATURES WILL REMAIN ABOVE NORMAL WITH NO RAIN. WENT VERY CLOSE TO MAV GUIDANCE DURING THESE TIME FRAMES. && .LONG TERM /WEDNESDAY THROUGH SUNDAY/... THE EXTENDED PERIOD BEGINS WITH RIDGING OVER THE EASTERN SEABOARD WHILE A SHORTWAVE MOVES EASTWARD FROM JUST NORTH OF THE GREAT LAKES TOWARDS EASTERN CANADA. 850 MB TEMPS WILL CONTINUE TO RUN 1-2 STD ABOVE NORMAL...WITH VALUES AROUND 8 DEGREES C. THIS SHOULD ALLOW FOR HIGHS TO RANGE FROM THE MIDDLE 60S IN THE DACKS TO THE MIDDLE 70S IN THE MID HUDSON VALLEY. THE AFOREMENTIONED DISTURBANCE WILL RUN INTO THE RIDGE...FLATTENING THE 500MB FLOW BY WEDNESDAY NIGHT. AT THE SURFACE...THIS FEATURE WILL DRAG A WEAK COLD FRONT THROUGH THE REGION FOR THE SAME TIME PERIOD. WITH THE BEST UPPER LEVEL DYNAMICS LIFTING NORTH ACROSS QUEBEC AND LITTLE MOISTURE TO WORK WITH...THIS SYSTEM SHOULD ONLY PRODUCE SCT SHOWERS AT BEST. 12Z GFS ENSEMBLES SHOW THE OPERATIONAL RUN TO BE THE MOST PESSIMISTIC WITH PRECIP...SO AM CONTINUING ONLY LOW CHC POPS OVER THE NORTHERN 3/4 OF THE CWA...WITH SLT CHC POPS ACROSS THE FAR SOUTH. THE GFS SHOWS LIS DROPPING TO JUST NEAR ZERO AND WITH ABOUT 100-200 J/KG OF CAPE PROJECTED. SOME T-STORM ACTIVITY COULD BE POSSIBLE...BUT WITH CONFIDENCE BEING LOW...WILL CONTINUE TO LEAVE IT OUT OF THE FORECAST FOR NOW. BEHIND THIS SYSTEM...CAA WILL DROP 850 TEMPS...ALLOWING LOWER MAX TEMPS ON THURS...YET STILL VERY COMFORTABLE AND STILL SEVERAL DEGREES ABOVE NORMAL. PLENTY OF SUNSHINE SHOULD RETURN FOR THURSDAY AS WELL AS A 1026 MB HIGH RAPIDLY MOVES IN BEHIND THE SYSTEM. THE NEXT FEATURE TO WATCH WILL BE A SYSTEM MOVING ACROSS THE PLAINS FOR THE WEEKEND. YESTERDAYS MODELS RUNS SEEMED TO CUT THIS FEATURE OFF QUICKER...SLOWING ITS EASTWARD PROGRESS. TODAY/S 12Z EURO SHOWS THIS NEXT FEATURE BEING A LOT MORE PROGRESSIVE...MOVING IT ACROSS THE REGION ON SAT NIGHT INTO SUNDAY...WHILE THE 12Z GFS CONTINUES TO SHOWS THIS FEATURE CLOSING OFF OVER THE GREAT LAKES...AND AFFECTING OUR WEATHER STARTING LATE ON SATURDAY AND CONTINUING INTO EARLY NEXT WEEK. WITH UNCERTAINTIES REGARDING THIS SYSTEM...WILL CONTINUE TO SHOW JUST CHC POPS FOR -SHRA ACROSS THE CWA STARTING ON SATURDAY AND CONTINUING THROUGH SUNDAY. IN GENERAL...THE LONG TERM PERIOD LOOKS TO HAVE PRECIP AVERAGING BELOW NORMAL AND TEMPERATURES AVERAGING ABOVE NORMAL. && .AVIATION /19Z SUNDAY THROUGH FRIDAY/... FOR KGFL TO KALB...VFR CONDITIONS EXPECTED WITH LIGHT WINDS AND NEAR IDEAL FAVORABLE AVIATION CONDITIONS. THIS DOES CHANGE FOR KPOU. WITH SOUTHEAST WIND TRAJECTORIES ORIGINATING FROM THE MARINE INFLUENCE OFF THE COOLER WATERS OF LONG ISLAND SOUND AND THE ATLANTIC...A LAYER OF LOW STRATUS WILL REMAIN PROBLEMATIC. LATEST FORECAST SOUNDINGS FROM THE NAM/WRF AND RUC13 SUGGEST THIS IFR CEILING WILL BECOME PREVALENT OVERNIGHT AND WILL REINTRODUCE THOSE 1000 FOOT CIGS. CONDITIONS WILL IMPROVE THROUGH THE DAYLIGHT HOURS MONDAY MORNING. OUTLOOK... MON PM-WED...VFR...NO SIGNIFICANT WEATHER. WED NIGHT...VFR/MVFR WITH A CHANCE FOR RAIN SHOWERS. THU...VFR...NO SIGNIFICANT WEATHER. && .FIRE WEATHER... DRY WEATHER IS FORECAST AT THROUGH TUESDAY NIGHT. THE NEXT CHANCE OF ANY SIGNIFICANT RAIN WILL HAVE TO WAIT UNTIL A COLD FRONT CROSSES THE REGION BY WEDNESDAY. A MARINE AIRMASS DID BRING HIGHER RH HUMIDITY VALUES TO MOST OF THE REGION SOUTH TODAY...AS WELL AS STRATUS WELL TO THE SOUTH OF ALBANY. OVERALL...RH VALUES WERE ABOUT 20 PERCENT HIGHER THAN SATURDAY. RH VALUES WILL RECOVER TO BETWEEN 90 AND 100 PERCENT TONIGHT. WITH LESS OF A MARINE INFLUENCE...AFTERNOON RH VALUES WILL DROP BACK INTO THE 30S MOST PLACES ON MONDAY....THEN RECOVER TO BETWEEN 80 AND 90 PERCENT ON MONDAY NIGHT...THEN DROP BACK AROUND 30 PERCENT BY TUESDAY AFTERNOON. A SSE SURFACE WIND WILL DIMINISH TO LIGHT MOST PLACES OVERNIGHT...THEN RESUME FROM THE SE 5 TO 15 MPH ON MONDAY AND AGAIN TUESDAY AFTER BECOMING LIGHT OR CALM MONDAY NIGHT. && .HYDROLOGY... FLOOD WARNINGS REMAIN POSTED ALONG THE NORTHERN BRANCH OF THE HUDSON RIVER AT SCHUYLERVILLE AND FORT EDWARD...THE SCHROON RIVER AT RIVERBANK AND SACANDAGA RIVER AT THE RESERVOIR. WARM TEMPERATURES AND THE SNOWMELT ARE THE CULPRIT WITH STILL SEVERAL INCHES OF WATER EQUIVALENT REMAINING IN HERKIMER COUNTY /ADIRONDACKS/ INCLUDING THE SOUTHERN GREEN MOUNTAINS OF VERMONT. SO EXPECT RIVER LEVELS IN OUR NY CWA AT THESE LOCATIONS TO REMAIN HIGH INCLUDING INDIAN LAKE...NORTH CREEK AND PERHAPS THE WEST CANADA CREEK WITH THE RUNOFF FROM THE MOUNTAINS. WE WILL STILL REMAIN RATHER MILD SO UNTIL THE SNOWPACK COMPLETELY ERODES...RIVER LEVELS WILL REMAIN HIGH. THE NEXT CHANCE FOR RAINFALL ARRIVES LATE WEDNESDAY AND WEDNESDAY NIGHT. && .ALY WATCHES/WARNINGS/ADVISORIES... CT...NONE. NY...NONE. MA...NONE. VT...NONE. && $$ SYNOPSIS...BGM NEAR TERM...HWJIV SHORT TERM...HWJIV LONG TERM...FRUGIS AVIATION...BGM FIRE WEATHER...HWJIV HYDROLOGY...BGM ct AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE ALBANY NY 122 PM EDT SUN APR 20 2008 .SYNOPSIS... HIGH PRESSURE NEAR NOVA SCOTIA WILL KEEP THE FAIR AND DRY WEATHER PATTERN IN PLACE ACROSS EASTERN NEW YORK AND WESTERN NEW ENGLAND TODAY THROUGH EARLY NEXT WEEK. HIGH TEMPERATURES THIS AFTERNOON WILL BE A LITTLE COOLER THAN YESTERDAY...DUE TO AN EAST TO SOUTHEASTERLY FLOW OF SLIGHTLY COOLER AIR...AND SOME HIGH CLOUDS ASSOCIATED WITH A LOW PRESSURE SYSTEM OVER THE MID ATLANTIC REGION. HIGH TEMPERATURES TODAY THROUGH TUESDAY WILL BE 10 TO 15 DEGREES ABOVE NORMAL FOR LATE APRIL. && .NEAR TERM /UNTIL 6 PM THIS AFTERNOON/... MARINE INFLUENCE CONTINUES TO PLAQUE THE MID HUDSON VALLEY WITH AN EXTENSIVE STRATUS DECK. THIS WILL CUT BACK ON HIGH TEMPERATURES AND CURRENT TRENDS FROM THE 1KM VISIBLE SUGGEST THIS CLOUD DECK IS ADVANCING NORTHWARD. WILL ADJUST CLOUD COVER UPWARD FOR THE ENTIRE CWA AND DROP TEMPERATURES ACCORDINGLY BY A FEW DEGREES. HOWEVER...WITH BREAKS AND THIN NATURE OF THE CLOUD COVER...TEMPERATURES INTO THE MOHAWK VALLEY AND NORTH OF THE MID HUDSON VALLEY SHOULD TAP OUT INTO THE LOWER 70S. OTHERWISE...NO OTHER CHANGES NEEDED AT THIS TIME. && .SHORT TERM /6 PM THIS AFTERNOON THROUGH TUESDAY NIGHT/... THE REX BLOCK WITH A RIDGE OVER THE NORTHEAST NORTH OR JUST POLEWARD OF THE CUTOFF LOW OVER THE MID ATLANTIC REGION CONTINUES TO HOLD THROUGH THE SHORT TERM. THE CUTOFF GETS STEERED AND DIRECTED FURTHER SOUTHEAST MONDAY INTO TUESDAY...THAT IT WILL BE PUSHED BACK TOWARD SC AND FL. MEANWHILE...THE CLOSED ANTICYCLONE AT H500 CONTINUES TO BE ANCHORED OVER NY AND NEW ENGLAND. MIN TEMPS SUNDAY EVENING WILL DEPEND ON HOW MUCH RADIATIONAL COOLING OCCURS. SOME CIRRUS WILL BE LINGERING AND THE BOUNDARY LAYER WINDS WILL BE CALM. WITH PARTLY CLOUDY CONDITIONS...WE LEANED TOWARDS THE GFSMOS MINS WITH 30S OVER THE HILLS...MTNS...SRN VT...AND THE LAKE GEORGE REGION....WITH LOWER TO MID 40S ELSEWHERE. MONDAY THROUGH TUESDAY...MORE PLEASANT WEATHER WITH MAX TEMPS STILL ABOUT 10-15 DEGREES ABOVE NORMAL ON MON WITH HIGH PRESSURE EAST OF THE GULF OF MAINE IN CONTROL. TUESDAY MORNING MINS WILL BE A BIT CHILLY WITH SOME DECENT RADIATIONAL COOLING WITH CALM AIR...MOSTLY CLEAR SKIES...AND DRY/PARCHED SOIL IN SOME LOCATIONS. WE WENT 1-3 DEGREES COOLER THAN THE GFSMOS TEMPS. TUESDAY TEMPS COULD SKIP UP A LITTLE WARMER IN THE MID 70S IN THE VALLEYS /60S OVER THE HILLS AND MTNS/ WITH GOOD DRY ADIABATIC MIXING FROM 850 MB /TEMPS AROUND +8C/ AND MOSTLY SUNNY CONDITIONS. TUESDAY NIGHT...A COLD FRONT APPROACHING FROM ERN ONTARIO...THE GREAT LAKES REGION AND THE MIDWEST ASSOCIATED WITH A BROAD UPPER LEVEL TROUGH...MAKES A RUN AT THE NORTHEAST. HOWEVER...THE FRONT LOOKS LIKE IT WILL GO THROUGH SOME FRONTALYSIS RUNNING INTO THE HIGH AMPLITUDE RIDGE OVER THE EAST COAST OF NORTH AMERICA. IT DOESN/T APPEAR ANY PCPN WITH THIS WEAKENING FRONT WILL OCCUR UNTIL LATE WED PM INTO THE EVENING /IF THAT/ BASED ON THE GFS/ECMWF. WE JUST INCREASED SOME CLOUDS AHEAD OF THIS BOUNDARY WED MORNING. && .LONG TERM /WEDNESDAY THROUGH SATURDAY/... ABOVE NORMAL TEMPERATURES WILL CONTINUE FOR THE EXTENDED PERIOD. THERE WILL BE A CHANCE FOR SOME SHOWERS WEDNESDAY AND WEDNESDAY NIGHT AS AN UPPER TROUGH/SHORT WAVE MOVES ACROSS THE GREAT LAKES AND NORTHERN NEW YORK STATE PUSHING INTO RIDGE. AT THE SURFACE A WEAKENING COLD FRONT WILL PUSH THROUGH AREA BRINGING A CHANCE FOR SHOWERS. THE RIDGE AMPLIFIES THURSDAY INTO FRIDAY. IN THE MEANTIME A STRONG PACIFIC SHORT WAVE WILL MOVE INTO THE WESTERN UNITED STATES. THE GFS AND ECMWF ARE IN BETTER AGREEMENT HANDLING THIS FEATURE BUT THERE STILL ARE FAIRLY LARGE DIFFERENCES. THE ECMWF HAS A MORE AMPLIFIED RIDGE WHILE THE GFS IS STRONGER WITH PACIFIC ENERGY ACTUALLY CLOSING OFF A LOW OVER THE UPPER MID WEST BY FRIDAY. BOTH MODELS BREAK RIDGE DOWN AS WE HEAD INTO THE WEEKEND BRINGING OUR NEXT CHANCE FOR RAIN AS THE LOW PRESSURE SYSTEM MOVES INTO THE REGION. && .AVIATION /18Z SUNDAY THROUGH THURSDAY/... FOR KGFL TO KALB...VFR CONDITIONS EXPECTED WITH LIGHT WINDS AND NEAR IDEAL FAVORABLE AVIATION CONDITIONS. THIS DOES CHANGE FOR KPOU. WITH SOUTHEAST WIND TRAJECTORIES ORIGINATING FROM THE MARINE INFLUENCE OFF THE COOLER WATERS OF LONG ISLAND SOUND AND THE ATLANTIC...A LAYER OF LOW STRATUS WILL REMAIN PROBLEMATIC. LATEST FORECAST SOUNDINGS FROM THE NAM/WRF AND RUC13 SUGGEST THIS IFR CEILING WILL BECOME PREVALENT OVERNIGHT AND WILL REINTRODUCE THOSE 1000 FOOT CIGS. CONDITIONS WILL IMPROVE THROUGH THE DAYLIGHT HOURS MONDAY MORNING. OUTLOOK... MON PM-WED...VFR...NO SIGNIFICANT WEATHER. WED NIGHT...VFR/MVFR WITH A CHANCE FOR RAIN SHOWERS. THU...VFR...NO SIGNIFICANT WEATHER. && .FIRE WEATHER... ...SOUTHEASTERLY WIND GUSTS TODAY UP TO 20 MPH IN PERSISTENT DRY PATTERN... HIGH PRESSURE NEAR NOVA SCOTIA WILL KEEP DRY WEATHER OVER THE REGION OVER THE NEXT SEVERAL DAYS. MOST OF EASTERN NEW YORK AND WESTERN NEW ENGLAND HAS NOT RECEIVED MEASURABLE RAINFALL IN ABOUT A WEEK. HIGH TEMPERATURES WILL BE COOLER TODAY COMPARED TO THE PREVIOUS TWO DAYS...BUT MINIMUM RH VALUES IN THE AFTERNOON WILL BE MAINLY IN THE 30 TO 40 PERCENT RANGE WITH SOME UPPER 20S ACROSS THE LAKE GEORGE REGION...SOUTHERN VERMONT AND THE BERKSHIRES. EAST OR SOUTHEAST WINDS OF 10 TO 15 MPH WILL BE COMMON WITH GUSTS TO ABOUT 20 MPH. RELATIVE HUMIDITY LEVELS WILL RECOVER TO BETWEEN 80 AND 100 PERCENT MONDAY MORNING...THEN LOWER TO 25 TO 40 PERCENT IN THE AFTERNOON. EXPECT THE WINDS TO GO LIGHT TO CALM SUNDAY NIGHT...AND BE LIGHT FROM THE SOUTHEAST AT 5 TO 10 MPH ON MONDAY. THERE HAVE BEEN MANY BRUSH FIRES ACROSS THE REGION THE PAST FEW DAYS WITH THE MOST NOTABLE ONE TAKING PLACE DOWN IN CENTRAL ULSTER COUNTY IN MINNEWASKA PARK. && .HYDROLOGY... DRY WEATHER AND ABOVE NORMAL TEMPERATURES ARE FORECAST OVER THE NEXT SEVERAL DAYS. THIS WILL RESULT IN CONTINUED SNOWMELT FROM AREAS IN THE ADIRONDACKS WHERE SIGNIFICANT SNOW PACK STILL REMAINS WITH SNOW LIQUID EQUIVALENTS OF THREE TO ISOLATED TEN INCH AMOUNTS. WATER STORED IN SCHROON...BRANT...AND THE GREAT SACANDAGA LAKES HAS RESULTED IN CONTINUED FLOODING ALONG THE SCHROON RIVER FROM SCHROON LAKE TO THE HUDSON RIVER...AND ALONG THE HUDSON RIVER FROM GLENS FALLS TO STILLWATER...INCLUDING THE STILLWATER FLATS. THE HUDSON WILL ALSO BE VERY CLOSE TO FLOOD AT MECHANICVILLE. EAST CANADA CREEK WILL BE NEAR BANKFULL AND WEST CANADA CREEK WILL GET VERY CLOSE TO BANKFULL FROM HINCKLEY DOWNSTREAM TO THE MOHAWK RIVER. SNOW MELT IN THE SOUTHERN GREEN MOUNTAINS HAS BOOSTED RIVER FLOWS ON THE BATTENKILL...WALLOOMSAC...WILLIAMS...SAXTONS...WEST...AND DEERFIELD RIVERS BUT THOSE RIVERS WILL REMAIN BELOW FLOOD. LITTLE RAINFALL IS EXPECTED OVER THE NEXT 5 DAYS WITH A DRY AIR MASS HOLDING OVER THE EAST COAST. PLEASE REFER TO THE LATEST FLOOD STATEMENTS AND THE AHPS GRAPHICS ON THE WEBSITE FOR CURRENT DETAILS ON SPECIFIC RIVERS AND WARNINGS. && .ALY WATCHES/WARNINGS/ADVISORIES... CT...NONE. NY...NONE. MA...NONE. VT...NONE. && $$ SYNOPSIS...WASULA NEAR TERM...BGM SHORT TERM...WASULA LONG TERM...IAA AVIATION...BGM FIRE WEATHER...WASULA HYDROLOGY...WASULA/RCK WWW.WEATHER.GOV/ALBANY ct AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LINCOLN IL 1200 AM CDT SUN APR 20 2008 .DISCUSSION... ISSUED 830 PM CDT SAT APR 19 2008 LOW PRESSURE NOW CENTERED NEAR CHICAGO AND SLOPES UP TO SOUTHERN INDIANA IN THE MID/UPPER LEVELS. SURFACE TROUGH PREVIOUSLY ANALYZED FROM THE LOW SOUTHWARD THROUGH CENTRAL ILLINOIS HAS BECOME LESS DISTINCT AS WINDS DECREASE. DRIER AIRMASS OVER THE EASTERN HALF OF THE AREA WITH AFTERNOON DEWPOINTS IN THE LOW/MID 40S IS NOW MOISTENING UP WITH DEWPOINTS NOW RISING TOWARD 50. MANY AREAS EAST OF INTERSTATE 55 HAVE CLEARED OUT...WHICH WILL PROMOTE RADIATIONAL COOLING THIS EVENING. ALL OF THESE FACTORS WILL FAVOR THE FORMATION OF FOG OVERNIGHT...WHICH WILL LIKELY BE DENSE OVER MANY AREAS. FORECAST SOUNDINGS FROM THE SHORT-RANGE RUC MODEL SUPPORT THIS SCENERIO AS WELL. WOULD NOT BE SURPRISED IF A DENSE FOG ADVISORY BECOMES REQUIRED LATER TONIGHT...BUT WILL HOLD OFF ON ANY ISSUANCE UNTIL THE AERIAL EXTENT BECOMES BETTER DEFINED. AREAS OF THE WEST THAT DID NOT REALLY CLEAR OUT MAY NOT MEET ADVISORY CRITERIA. FORECASTS ALREADY MENTION FOG FOR TONIGHT...SO WILL LET THAT RIDE FOR THE MOMENT. RADAR DATA SHOWS ONLY A FEW WEAKENING SPITS OF DRIZZLE HERE AND THERE SO NO NEED TO MAKE CHANGES IN THE POPS...WHICH HAVE SLIGHT CHANCE ENDING AT MIDNIGHT. WILL SEND OUT A ZONE FORECAST UPDATE LATER THIS EVENING TO FRESHEN UP THE TEMPORAL WORDING...AND WILL ALSO MONITOR FOG TRENDS FOR ANY NEEDED ADVISORIES. 04 && .AVIATION... ISSUED 1200 AM CDT SUN APR 20 2008 LIGHT PRECIPITATION EARLIER IN THE EVENING HAS PRETTY MUCH DIED OUT...AND AREA SHOULD REMAIN PRECIPITATION-FREE THE REMAINDER OF THE TAF PERIOD. EXPECT INCREASING FOG WITH TIME OVERNIGHT...ESPECIALLY OVER AREAS THAT HOLD ON TO CLEAR SKIES THE LONGEST. SCT-BKN MULTI-LAYERED CLOUDS WILL GRADUALLY FILL IN WITH 500-1500 FT CIGS BECOMING COMMON. ALSO EXPECT VSBYS AT OR BELOW 1SM IN FOG. FOG AND STRATUS WILL GRADUALLY LIFT INTO SCT-BKN 1500-2500 FT STRATOCU DECK 14Z-18Z SUN...THEN FILL IN AGAIN SOMEWHAT WITH SURFACE HEATING. THE BEST CHANCES FOR LOWER CLOUDS AFTER 00Z MON WILL BE OVER THE EAST...CLOSER TO THE SLOWLY DEPARTING UPPER LOW. AREAS OF FOG WILL BE POSSIBLE AGAIN MAINLY AFTER 06Z MON...HOWEVER DO NOT EXPECT VSBYS AS LOW AS THIS MORNING. 04 && .PREV DISCUSSION... ISSUED 305 PM CDT SAT APR 19 2008 SHORT TERM...TONIGHT THROUGH MONDAY. UPPER LOW WAS LOCATED JUST EAST OF MATTOON THIS AFTERNOON...WITH THE CIRCULATION SHOWING UP RATHER NICELY ON VISIBLE SATELLITE IMAGERY. MSAS INDICATED SFC LOW OVER NORTHERN ILLINOIS HAD WEAKENED TO AN OPEN TROUGH AT 2 PM...AND SFC WIND FIELDS SUGGEST WEAK CIRCULATION AT THE SFC ROUGHLY CO-LOCATED WITH THE UPPER LOW NEAR MATTOON. PLENTY OF BREAKS HAVE DEVELOPED IN THE CLOUD COVER ACROSS THE REGION... ESPECIALLY NORTH AND WEST OF THE I-72 CORRIDOR. IN AREAS WHERE THE SUN HAS PEEKED THROUGH...TEMPERATURES HAVE QUICKLY REBOUNDED INTO THE LOWER AND MIDDLE 60S. A FEW HEAVIER CONVECTIVE SHOWERS HAVE DEVELOPED NORTHWEST OF THE ILLINOIS RIVER WHERE TEMPS HAVE REBOUNDED THE MOST. IL STATE POLICE EARLIER REPORTED FUNNEL CLOUDS ASSOCIATED WITH A CONVECTIVE CELL OVER LA SALLE COUNTY IN THE LOT CWA. LAPS ANALYSIS INDICATES NON-SUPERCELL TORNADO PARAMETER OF 1.0+ OVER THAT AREA ... NOT SURPRISING GIVEN SFC TEMP OF 64F AT KVYS LEADING TO GREATER INSTABILITY WITHIN AN ARC OF ENHANCED STRETCHING POTENTIAL THAT EXISTS ACROSS THE ILLINOIS VALLEY PER LAPS. ALL THIS MAKES SENSE CONSIDERING ENHANCED VORTICITY WITH UPPER LOW OVER THE AREA. GIVEN OBSERVATIONS...WOULD NOT BE ENTIRELY SURPRISED TO SEE A FUNNEL CLOUD REPORT SHOULD WE MANAGE TO GET SOME HEAVIER CONVECTIVE CELLS TO DEVELOP. HIGHEST RISK WOULD BE NORTHWEST OF THE I-55 CORRIDOR... ESPECIALLY NEAR THE ILLINOIS RIVER. THIS RISK SHOULD DIMINISH AFTER SUNDOWN... AND ANY REMAINING SHOWERS SHOULD DISSIPATE SHORTLY AFTER SUNDOWN AS WELL. DRIER WX AND WARMING TEMPS ON TAP FOR SUNDAY AND MONDAY AS SHORTWAVE RIDGING DEVELOPS ACROSS THE MISSISSIPPI VALLEY IN THE WAKE OF OUR DEPARTING UPPER LOW. CU RULE AND MODEL SOUNDINGS SUGGEST A FEW BANDS OF ENHANCED CU DEVELOPMENT TOMORROW AFTERNOON...BUT OVERALL EXPECT PARTLY CLOUDY SKIES AND TEMPS WITHIN A COUPLE DEGREES EITHER SIDE OF 70 F. LONG TERM...TUESDAY THROUGH SATURDAY. LONGER RANGE MODELS STILL DEPICTING STRONG RIDGING ACROSS THE NORTHWEST PACIFIC INTO MAINLAND ALASKA THROUGH THE END OF NEXT WEEK. THIS WILL SUPPORT CONTINUED TROUGHING ACROSS THE WESTERN HALF OF THE CONUS...BUT PERSISTENT RIDGE EAST OF THE APPALACHIANS WILL PREVENT ANY REALLY STRONG DISTURBANCES FROM COMING THROUGH. WEAK UPPER LEVEL DISTURBANCE WILL RIDE OFF TO OUR NORTHWEST PUSHING A SLOW MOVING COLD FRONT THROUGH THE AREA TUESDAY. LONGER RANGE MODELS SHOW SOME DIFFERENCES WITH TIMING...BUT SUGGEST A PACIFIC DISTURBANCE UNDERCUTTING THE BLOCKING RIDGE OFF THE WEST COAST...WILL APPROACH THE AREA FRIDAY...POSSIBLY FOLLOWED BY A STRONGER REINFORCING WAVE TOWARDS THE WEEKEND. CONSIDERABLE UNCERTAINTY EXISTS BEYOND THURSDAY GIVEN THE RATHER COMPLICATED UPSTREAM PATTERN. EITHER WAY...THE UPCOMING WORK WEEK DOES LOOK TO BE RATHER QUIET CONSIDERING THE TIME OF YEAR. HARDIMAN && .ILX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ il AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DODGE CITY KS 242 PM CDT SUN APR 20 2008 .DISCUSSION... DAYS 1-2... WINDS AND TEMPERATURES WILL CONTINUE TO BE THE MAIN FORECAST CONCERNS. 12Z MAPS CONTINUE TO DIG THE NEXT UPPER TROUGH DIGGING INTO THE WESTERN CONUS, WITH A 110 KT JET ON THE BACKSIDE OF IT AND 140 M HEIGHT FALLS ACROSS NV. AT 700 AND 850MB, WARM TEMPS OF 9 C AND 21 C RESPECTIVELY HAVE MOVED UP INTO WESTERN KS. AT THE SFC, THERE WAS A DECENT PRESSURE GRADIENT WITH THE LOW OVER EASTERN WY, AND SOUTHERLY WINDS WERE BRINGING UP DEWPOINTS OF 50 PLUS CLOSE TO THE RED RIVER. THE TRULY RICH MOISTURE WAS STILL DOWN OVER CENTRAL KS. EVEN WITH THE TIGHT GRADIENT, WINDS ARE NOT QUITE AS HIGH AS EXPECTED THUS FAR. THE NAM AND RUC ARE ADVERTISING A SURGE OF 25 PLUS KTS AROUND 21Z, BUT AM ON THE FENCE ABOUT KEEPING THE ADVISORY. TONIGHT, A SHORTWAVE WILL EJECT OFF THE MAIN TROUGH IN THE WEST AND MOVE INTO THE NORTHERN PLAINS. THIS SHOULD SHIFT THE SFC TROUGH EASTWARD AND PUSH A COLD FRONT DOWN INTO THE CWA BY EARLY MORNING. WITH NOT MUCH MOISTURE TONIGHT, DON`T THINK THAT WE`LL SEE ANY PRECIP ALONG THE FRONT. WINDS WILL SHIFT AROUND TO THE NORTH AND WE SHOULD GET SOME COOLER AIR FILTERING IN TOWARDS MORNING. KEPT LOWS IN THE 40S IN THE NORTHWEST TO THE 50S IN THE SOUTHEAST. SOUTHWESTERLY FLOW ALOFT WILL CONTINUE INTO MONDAY, WITH THE SFC LOW RE-DEVELOPING JUST SOUTH OF EHA. THE FRONT SHOULD BE SOMEWHERE NEAR THE KS/OK BORDER, AND NORTHEASTERLY WINDS WILL BRING UPSLOPE. 850MB TEMPS ARE ONLY SLIGHTLY COOLER, AND WITH SUNSHINE, WE SHOULD GET BACK UP INTO THE LOW 70S IN THE NORTH, WITH UPPER 70S NEAR THE OK BORDER CLOSE TO THE FRONT. WINDS COULD PICK UP AGAIN BY MONDAY AFTERNOON, WITH THE NAM AND RUC BOTH GETTING CLOSE TO 25 KTS FOR BRIEF PERIODS. HOWEVER, IT LOOKS LIKE ANOTHER BORDERLINE CASE SO WILL HOLD OFF ON A WIND ADVISORY FOR NOW. ANOTHER SHORTWAVE TROUGH WILL MOVE OUT INTO THE PLAINS MONDAY EVENING, AND UPSLOPE FLOW SHOULD BRING SOME STRATUS NEAR OR INTO OUR SOUTHEASTERN COUNTIES. DO NOT AT THIS POINT THINK THAT WE WILL GET ANY PRECIP FROM IT, BUT CONTINUED WITH THE SILENT POPS WE HAD GOING. FLOW WILL BECOME NEAR ZONAL BY TUESDAY, WITH THE SFC HIGH BUILDING IN BEHIND THE FRONT. 850MB TEMP WILL CONTINUE TO BE IN THE TEENS, AND ANY CLOUDS SHOULD DISSIPATE BY AFTERNOON. HIGHS WILL BE IN THE 70S. DAYS 3-7... THE MAIN FORECAST DECISION CENTERS AROUND TEMPERATURES DAYS 3 AND 4...FOLLOWED BY PRECIP CHANCES THE SAME TIME FRAME. THERE APPEARS TO BE AN UPPER LEVEL TROUGH COMING THROUGH THE PLAINS ON LATE WEDNESDAY AND THROUGH THURSDAY NIGHT. OUR CWA IS ON THE BASE PORTION OF THE TROUGH SO MOST CONVECTIVE ACTION WILL BE NORTH OF US INITIALLY AND THEN TO THE EAST OF DDC`S CWA THURSDAY NIGHT. SO THE 20 POPS WEDNESDAY AFTERNOON SEEM APPROPRIATE AND INCREASING TO 30 POPS IN OUR EASTERN 2/3RDS CWA BY 12Z THURSDAY. AS THURSDAY HEAT UP INTO THE 80S...MORE CONVECTION COULD POP MAINLY IN THE EASTERN HALF OF OUR CWA DUE TO MORE MOISTURE BEING AVAILABLE. WILL ESSENTIALLY DROP ALL MENTION OF POPS BY 18Z FRIDAY AS ANY FRONT SHOULD BE SOUTHEAST OF US AND THE UPPER WAVE EAST OF WESTERN KANSAS. AFTER DAY 5...WE WILL BE BACK INTO A WESTERLY ZONAL FLOW ALOFT WITH HIGH PRESSURE AT THE SURFACE CENTERED TO OUR NORTH. SOMEWHERE ON LATE DAY 6 INTO DAY 7 (SAT-SUN)...A TROUGH LOOKS TO COME OFF THE ROCKIES AND INTO SOUTHWEST KANSAS. THIS COULD TRIGGER A FEW THUNDERSTORMS AND HAVE INTRODUCED 10 POPS FOR LATE SUNDAY INTO DAY 8 (MON). WITH THIS SYSTEM...BOUNDARIES WILL BE THE KEY FOCUS AREAS FOR CONVECTION AND WE WILL HAVE TO WAIT TO SEE IF THIS TROUGH MATERIALIZES. .AVIATION... VFR CIGS AND VSBYS THRU THE PERIOD...BUT WITH STRONG SOUTH WINDS IN THE 20 TO 30 MPH AND GUSTY RANGE THRU 01Z OR SO. WINDS WILL BECOME SOUTHEAST SHORTLY AFTER SUNSET AND SETTLE TO AROUND 15KTS FOR THE OVERNIGHT PERIOD. && .PRELIMINARY POINT TEMPS/POPS... DDC 47 71 45 72 / 0 0 10 0 GCK 44 70 44 70 / 0 0 10 0 EHA 42 75 44 73 / 0 0 10 0 LBL 44 75 45 73 / 0 0 10 0 HYS 45 70 44 71 / 0 0 10 0 P28 53 77 52 76 / 0 0 10 0 && .DDC WATCHES/WARNINGS/ADVISORIES... WIND ADVISORY UNTIL 8 PM CDT THIS EVENING FOR KSZ030-031-045-046- 064>066-078>081-087>090. RED FLAG WARNING UNTIL 8 PM CDT /7 PM MDT/ THIS EVENING FOR KSZ043-044-061>063-074>077-084>086. && $$ FN26/12/12 ks AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GOODLAND KS 1130 AM MDT SUN APR 20 2008 .DISCUSSION... HAVE TWEAKED FIRST PERIOD TEMP/DP/WIND GRIDS BASED ON CURRENT OBSERVATIONS AND SHORT TERM MODEL GUIDANCE. ALTHOUGH THERE IS GOOD AGREEMENT ON TEMPERATURE FORECAST DISCREPANCY STILL SHOWING UP WITH REGARD TO DEWPOINTS AND WINDS. RUC WANTS TO KEEP THE HIGHER DEWPOINTS UP AGAINST THE COLORADO/KS BORDER WHERE ITS ALSO FORECASTING LOWER WIND SPEEDS. NAM/RUC13 WANT TO PUSH THEM FURTHER EAST AND BRING THE EXPECTED HIGHER AND DRIER WINDS WITH THEM. NAM MIXING DEPTH TO 600MB OR SO VERIFIES OK WITH CURRENT SINGLE DIGIT DEWPOINTS ACROSS FAR EASTERN COLORADO. HAVE BLENDED IT WITH OTHER GUIDANCE FOR THE REST OF THE DAY. AT 17Z THE SURFACE TROUGH HAD MOVED THROUGH ALL OF FAR EASTERN COLORADO AND COUNTIES IMMEDIATELY EAST OF THE BORDER WHERE LOWER DEWPOINTS AND HIGHER/GUSTIER SOUTHWEST WINDS QUICKLY DEVELOPED. WILL CONTINUE PREVIOUS IDEA OF SLOWLY PUSHING THIS BOUNDARY EAST THROUGH THE DAY. WIND ADVISORY OVER GRAHAM AND NORTON COUNTIES MAY BE BORDERLINE BUT WILL ALLOW IT TO CONTINUE. AFTERNOON TEMPS GENERALLY 80-85. DDT && .AVIATION... FOR KGLD SKC WITH WINDS FROM THE SOUTHWEST AT 20G30KTS. AT KMCK SKC WITH WINDS FROM THE SOUTH AT 15G25KTS. BETWEEN 01-02Z BOTH SITES WILL LOSE THE GUSTS. BETWEEN 06Z-08Z A FRONT WILL MOVE INTO THE AREA SHIFTING WINDS TO THE NORTH/NORTHWEST AT 15G25KTS WITH THE INITIAL PUSH. SHORTLY THEREAFTER MAY LOSE SOME OF THE GUSTINESS. BY 17Z WINDS SHOULD VEER AROUND TO THE NORTHEAST AT 15-20KTS WITH ONLY SOME CIRRUS OVERHEAD. DDT && .FIRE WEATHER... AT 17Z RH VALUES ALREADY BELOW 15 PERCENT WEST OF A WRAY COLORADO TO GOODLAND AND LEOTI KANSAS LINE. WINDS FROM THE SOUTHWEST AT 20 TO 30 MPH. FOR THE REMAINDER OF THE DAY GUSTY SOUTHWEST WINDS AND DRIER AIR WITH RH VALUES OF 5 TO 15 PERCENT (LOWEST ACROSS COLORADO AND ADJACENT COUNTIES IN KS) WILL CONTINUE TO SPREAD EAST TOWARD GRAHAM AND NORTON COUNTIES. CURRENT FORECAST IN GOOD SHAPE AND WILL UPDATE FWFGLD PRODUCT SHORTLY. DDT && .GLD WATCHES/WARNINGS/ADVISORIES... KS...RED FLAG WARNING UNTIL 8 PM MDT /9 PM CDT/ THIS EVENING FOR KSZ001>003-013>015-027>029-041-042. WIND ADVISORY UNTIL 8 PM CDT THIS EVENING FOR KSZ004-016. NE...RED FLAG WARNING UNTIL 8 PM MDT /9 PM CDT/ THIS EVENING FOR NEZ079>081. CO...RED FLAG WARNING UNTIL 8 PM MDT THIS EVENING FOR COZ252>254. && $$ WFO GOODLAND ks AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TOPEKA KS 415 AM CDT SAT APR 19 2008 .DISCUSSION... THE DEPARTURE OF THE STRATUS DECK OUT OF THE EASTERN TIER OF COUNTIES AND THEN CONVECTIVE POTENTIAL ON MONDAY AND MONDAY NIGHT ARE THE FOCUS OF THE FORECAST PACKAGE. WATER VAPOR IMAGERY INDICATES COLD CORE LOW CONTINUING SLOWLY OFF TO THE EAST. LAST REMNANTS OF MOISTURE WERE PUSHING SOUTH THROUGH THE EXTREME EASTERN PORTION OF THE CWA...GENERALLY OVER AREAS EAST OF HIGHWAY 75 AT 07Z. AT THE SURFACE...LOW PRESSURE WILL PUSH SLOWLY EAST WITH UPPER LEVEL SYSTEM THIS MORNING ALLOWING WEAK RIDGING TO BUILD IN ACROSS THE CWA TODAY. EXPECT STRATUS TO LINGER JUST WEST OF THE KS/MO BORDER AROUND SUNRISE...SO HAVE KEPT SOME CLOUD COVER IN AROUND 12Z FOR LAWRENCE AND OTTAWA TO START OFF THE DAY. 06Z RUC INDICATES THAT STRATUS WILL PUSH EAST OF THE CWA BY 15Z...SO FROM 15Z ON HAVE SKC CONDITIONS OVER THE FORECAST AREA. ASSUMING STRATUS HAS EXITED OFF TO THE EAST AS EXPECTED BY MID MORNING HIGHS WILL CLIMB INTO THE LOWER 70S ACROSS THE CWA...WITH SOME UPPER 60S POSSIBLE WHERE STRATUS LINGERS THIS MORNING. WINDS WILL BE GENERALLY LIGHT AND VARIABLE WITHIN THE RIDGE AXIS TODAY...AND WILL EVENTUALLY COME AROUND TO THE SOUTH AS LEE TROUGHING BEGINS TO DEVELOP OVER THE HIGH PLAINS SENDING SURFACE RIDGE EAST OF THE CWA THIS EVENING. SHORTWAVE RIDGING WILL PUSH EAST OVER THE PLAINS TONIGHT AS AN UPPER LEVEL TROUGH CURRENTLY OVER THE NORTHWESTERN CONUS BUILDS SOUTHEAST INTO THE INTERMOUNTAIN WEST. A SHORTWAVE EMBEDDED IN THIS LARGER TROUGH WILL AID IN THE STRENGTHENING OF THE LEE TROUGH ON SUNDAY BRINGING STRONGER SOUTHERLY WINDS AND WARMER WEATHER THROUGH THE CWA. HIGHS ON SUNDAY ARE EXPECTED TO CLIMB INTO THE UPPER 70S TO LOWER 80S. BY SUNDAY NIGHT MODELS INDICATE THAT PERSISTENT SOUTHERLY FLOW FINALLY TAPS INTO DEEPER GULF MOISTURE...AND RAPID LOW LEVEL MOISTURE TRANSPORT IS CONSISTENTLY FORECAST IN ALL GUIDANCE. ECMWF AND NAM WERE ABOUT 3-6 HOURS SLOWER WITH THE STRONGEST MOISTURE RETURN WHEN COMPARED TO THE GFS. GENERAL CONSENSUS WAS TO ADOPT THE SLIGHTLY SLOWER MOISTURE TRANSPORT AND ASSOCIATED STRATACUMULUS DECK...SO BACKED OFF ON CLOUD COVER AROUND 06Z MONDAY...AND THEN BROUGHT STRATUS RAPIDLY NORTH BY 12Z OVER THE ENTIRE FORECAST AREA. THE SHORTWAVE TROUGH WILL CONTINUE ROTATING THROUGH THE LARGER TROUGH AXIS OVER THE WESTERN CONUS...SENDING THE LEE TROUGH/COLD FRONT SOUTHEAST THROUGH THE NORTHERN PLAINS AND TOWARDS CENTRAL KS BY MONDAY MORNING. THE SHORTWAVE TROUGH EJECTS RAPIDLY NORTH INTO SOUTHERN CANADA BY MONDAY MORNING...SO WOULD EXPECT THE FRONT TO STALL OUT AT SOME POINT DURING THE DAY ON MONDAY...HOWEVER THE SPEED OF THE FRONT AND HOW FAR SOUTHEAST IT PROGRESSES BEFORE STALLING OUT REMAIN UNCERTAIN WITH PROGRESSIVE RUNS OF THE ECMWF ADVERTISING FASTER SOLUTIONS WHILE THE GFS OFFERS A SLOWER FRONTAL MOVEMENT SOLUTION. A SECONDARY SHORTWAVE TROUGH ROTATING THROUGH THE BASE OF THE LARGER TROUGH WILL BRING RENEWED PRESSURE FALLS OVER SOUTHEASTERN CO DURING THE DAY ON MONDAY WHICH WILL DEFINITELY STALL ANY POTENTIAL PROGRESS THE FRONT WAS MAKING...AND POTENTIALLY CAUSE IT TO RETROGRADE SOMEWHAT AS SURFACE LOW DEEPENS AND BEGINS TO MOVE NORTHEAST MONDAY AFTERNOON. SOUTH OF THE FRONT GULF MOISTURE AND BREAKS IN THE STRATUS DECK WILL DESTABILIZE THE ATMOSPHERE...SO THE EXACT POSITION OF THE FRONT IS VERY IMPORTANT FOR CONVECTIVE POTENTIAL MONDAY AFTERNOON. WITH 24 HOURS OF SOUTHWESTERLY MID LEVEL FLOW A STRONG EML WILL BE IN PLACE OVER THE FORECAST AREA...SO CONVECTION WILL LIKELY BE LOCATED NEAR THE CONVERGENCE AXIS ALONG THE FRONTAL BOUNDARY...AND WILL DEPEND ON THE PATH THE SHORTWAVE TROUGH TAKES AS IT EJECTS NORTHEAST INTO THE CENTRAL PLAINS MONDAY AFTERNOON. LARGELY DUE TO THE STRENGTH OF THE EML...HAVE KEPT POPS IN THE SLIGHT CHANCE CATEGORY MONDAY AFTERNOON WITH SEVERAL FACTORS NEEDING TO COME TOGETHER TO ENHANCE CONVECTIVE POTENTIAL. IF THUNDERSTORMS DO MANAGE TO DEVELOP MONDAY AFTERNOON OR EVENING...THERE IS A PRETTY GOOD CHANCE THE STORMS WOULD BE SEVERE WITH MLCAPE VALUES IN THE 1200-1800 J/KG RANGE...AND FAVORABLE HODOGRAPH/SHEAR PROFILES FOR SUPERCELLS IN THE WARM SECTOR RIGHT ALONG AND SOUTHEAST OF THE FRONTAL BOUNDARY. WITH SOMEWHAT LOW CONFIDENCE IN THE EML CAP BEING ERODED OR OVERCOME WILL HOLD OFF MENTIONING SVR WX IN THE HWO FOR NOW. MONDAY NIGHT...SLIGHTLY HIGHER CONFIDENCE IN PRECIPITATION AS SURFACE LOW PUSHES NORTHEAST THROUGH THE CWA AND FRONTAL BOUNDARY ONCE AGAIN SURGES SOUTHEAST. CONVERGENCE ALONG THE FRONT WILL BE GREATER MONDAY NIGHT...SO HAVE AT LEAST CHANCE WORDING IN THE FORECAST AT THIS TIME. BEHIND THE COLD FRONT AND SHORTWAVE TROUGH ON TUESDAY FEEL PRECIPITATION CHANCES WILL END QUICKLY AND HAVE BACKED OFF ON POPS...JUST MENTIONING RAIN SHOWERS FOR MOISTURE WRAPPED UP BEHIND THE LOW PRESSURE SYSTEM EXITING OFF TO THE NORTHEAST. REMOVED POPS TUESDAY NIGHT AND WEDNESDAY AS COLD FRONT LOOKS TO PUSH SOUTH AT LEAST INTO AR AND OK BEFORE STALLING OUT. NO CHANGES WERE MADE TO THE FORECAST BEYOND WEDNESDAY. CAVANAUGH && .AVIATION... STRATUS ON THE BACK SIDE OF SFC LOW OVER THE MID MS RIVER VALLEY IS SLOW TO EXIT TO THE EAST. HOWEVER STEADY PROPAGATION OF THE UPPER CLOSED LOW TO THE EAST WILL ALLOW SKIES TO EVENTUALLY CLEAR. THERE MAY BE SOME TEMPO CIGS AROUND 2 KFT THROUGH MID MORNING. OTHERWISE INCREASING SUBSIDENCE ON THE BACK SIDE OF THE UPPER SYSTEM WITH SHORTWAVE RIDGING MOVING OVERHEAD WILL PROVIDE P6SM SKC AND LIGHT WINDS FOR MOST OF THE DAY. WOLTERS && .TOP WATCHES/WARNINGS/ADVISORIES...NONE. && $$ ks AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE PADUCAH KY 950 PM CDT SAT APR 19 2008 .UPDATE... SATELLITE TRENDS INDICATE CLEARING WILL BE SLOW TO OCCUR OVERNIGHT...ESPECIALLY IN SOUTHERN ILLINOIS AND MUCH OF WESTERN KY. RAISED LOW TEMPS SLIGHTLY IN THOSE AREAS. OVER SW INDIANA...POCKETS OF CLEARING OCCURRED SURPRISINGLY CLOSE TO THE UPPER LOW. EXPECT CLOUDS TO REDEVELOP FROM THE WEST OR NORTHWEST ACROSS SW INDIANA. ADDED MENTION OF PATCHY FOG OVER PARTS OF SE MISSOURI...WHERE SKIES WILL REMAIN CLEAR OVERNIGHT. WINDS ALREADY WENT CALM IN MOST AREAS. REPLACED ISOLATED SHOWER WORDING WITH CHANCE OF SPRINKLES BASED ON RADAR TRENDS. && .PREVIOUS DISCUSSION /ISSUED 130 PM CDT SAT APR 19 2008/... SHORT TERM... /TONIGHT THROUGH TUESDAY NIGHT/ LATEST SURFACE ANALYSIS SHOWS LOW OVER CENTRAL IL WITH THE 12Z 500 MB LOW NEARLY VERTICALLY STACKED. A COLD FRONT EXTENDED FROM THE LOW TO THE SOUTHEAST OVER EASTERN KY...WITH AN ASSOCIATED TROF APPROACHING THE MISSISSIPPI RIVER. REG RADAR LOOP SHOWS SCATTERED LIGHT SHOWERS ROTATING AROUND THE LOW...ACROSS THE MOST OF THE FA. VIS SAT LOOP INDICATES SOME EASTWARD PROGRESS OF THE LOWS WITH THE TRAILING EDGE OF THE CLOUDS ALONG A LINE FROM THE BOOTHEEL THROUGH SGF TO KC. LDS CHART SHOWS NO CLOUD TO GROUND STRIKES OVER THE ENTIRE REGIONAL VIEW. BOTH THE 00Z AND 12Z SAT RUN OF THE NAM SHOW PRECIP OUT OF FA BY 00Z SUN. THE 14Z RUN OF THE RUC ALSO SUGGESTS A SIMILAR SCENARIO. THE 12Z SAT RUN OF THE GFS...INDICATES A FEW HUNDREDTHS IN THE EVV TO HOP CORRIDOR AS DOES THE 12Z SAT ECMWF...WITH THIS IN MIND WILL KEEP AT LEAST A SMALL CHANCE IN EXTREME EAST AFTER 00Z SUN AND MONITOR LATEST RADAR LOOP FOR EXACT CUTOFF LOCATION OF POPS...CLOSER TO PRESS TIME OF COURSE. WILL KEEP THINGS DRY SUNDAY AND MONDAY AS MODEL CONSENSUS IS ADVERTISING FOR THE MOST PART. THE LATEST 12Z MODEL RUNS ALSO SUGGEST THAT ANY PRECIP MONDAY NIGHT WOULD LIKELY BE LATE AND CONFINED TO THE WESTERN HALF SO HAVE ADJUSTED GRIDS TO REFLECT THE AFOREMENTIONED. ALTHOUGH THE MODELS ARE IN PRETTY GOOD AGREEMENT OF BRINGING NEG SFC LI`S TO THE REGION MONDAY NIGHT THE BEST MOISTURE DOES NOT ARRIVE TIL LATE AND MAINLY OVER THE WEST. SO HAVE LEFT POPS IN ALL NIGHT BUT TWEAKED THE COVERAGE TO THE WEST HALF. ATMOSPHERE REMAINS UNSTABLE THROUGH TUESDAY NIGHT SO WILL MAINTAIN THUNDER. CAPE VALUES SOAR INTO THE 2000 J/KG DURING THE DAY TUESDAY SO THAT WILL BE THE BEST CHANCE OF THUNDER COVERAGE. ALTHOUGH CAPE DROPS OFF A GREAT DEAL TUESDAY NIGHT BUT STILL REMAINS IN THE 200 J/KG WITH NEG LI`S. THIS COMBINED WITH FRONT BISECTING THE ARE...WILL ALSO CONTINUE THUNDER. IN ADDITION IF THE 12Z GFS CAPES ARE CORRECT MIGHT BE A CHANCE OF ACTIVE WEATHER TUESDAY...WILL MONITOR FOR SUCCESSIVE MODEL RUNS FOR POSSIBLE STRONG THUNDERSTORMS TUESDAY INTO TUESDAY EVENING. AS FOR SKY COVER BEGAN CLEARING LATE TODAY OVER SEMO AND SLOWLY SPREAD CLEARING EASTWARD TO THE EVV AREA AROUND SUNRISE SUNDAY. AS FOR TEMPS ONLY MINOR TWEAKS TO REFLECT LATEST GUIDANCE TRENDS. LONG TERM... /WEDNESDAY THROUGH SATURDAY/ IN THE MEDIUM RANGE PERIOD...THE 00Z ECMWF AND ITS ENSEMBLE MEAN ARE FAVORED BY HPC AND WILL BE FOLLOWED CLOSELY FOR THIS FORECAST. THIS RESULTS IN SOME SIGNIFICANT DEVIATIONS FROM THE 06Z AND 12Z GFS. THE GFS SOLUTION IS MUCH MORE PROGRESSIVE IN GENERAL...ADVERTISING COLD FRONT PASSAGES EARLY WEDNESDAY AND EARLY FRIDAY. A PATTERN SHIFT TO MORE OF A WESTERN TROUGH/EASTERN RIDGE REGIME IS FAVORED...WHICH LEADS TO A LESS ROBUST FRONTAL PASSAGE WEDNESDAY...AND A SLOWER ARRIVAL TO THE NEXT FRONT NOW FORECAST FOR LATE SATURDAY. FOLLOWING THE ECMWF SOLUTION RESULTS IN 20-30 POPS THROUGHOUT THE PERIOD WEDNESDAY THROUGH SATURDAY. IN GENERAL...HAVE 30S WITH THE WARM FRONT THURSDAY AND THE COLD FRONT SATURDAY...AND 20S WHEN WE ARE IN THE WARM SECTOR THURSDAY NIGHT THROUGH EARLY SATURDAY. WITH THE MID/UPPER LEVEL RIDGING THROUGH THE REGION...TEMPERATURES WILL REMAIN MILD THROUGH THE PERIOD. HIGHS WILL GENERALLY BE IN THE 70S WITH LOWS IN THE 50S EACH DAY. && .AVIATION... MVFR CONDITIONS IN SCATTERED SHOWERS WILL PERSIST FOR MUCH OF THE AFTERNOON...MAINLY ACROSS SOUTHERN ILLINOIS AND THE EVANSVILLE TRI STATE AREA. SKIES SHOULD CLEAR OUT OVER THE SOUTHWEST HALF OF THE AREA EARLY THIS EVENING...AND AS WINDS GO CALM...FOG DEVELOPMENT WILL BE LIKELY...WITH SOME AREAS LIKE KCGI POSSIBLY BECOMING LOCALLY DENSE. IN THE KEVV AND KOWB AREAS...MVFR TO LOW VFR CEILINGS ARE EXPECTED TO CONTINUE THROUGHOUT THE 18Z TAF PERIOD. THERE WILL BE A BREAK IN THE SHOWERY PRECIPITATION FROM LATE AFTERNOON TO LATE EVENING...BUT ANOTHER ROUND OF SHOWERS WITH MVFR CONDITIONS WILL BE POSSIBLE FROM 06Z-15Z. IN THE NORTHEAST...WINDS WILL WAFFLE 20-30 DEGREES OR SO EITHER SIDE OF DUE WEST THROUGHOUT THE PERIOD. && .PAH WATCHES/WARNINGS/ADVISORIES... KY...NONE. MO...NONE. IL...NONE. IN...NONE. && $$ UPDATE...MY PREVIOUS...KH/DS ky AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE PADUCAH KY 130 PM CDT SAT APR 19 2008 .SHORT TERM... /TONIGHT THROUGH TUESDAY NIGHT/ LATEST SURFACE ANALYSIS SHOWS LOW OVER CENTRAL IL WITH THE 12Z 500 MB LOW NEARLY VERTICALLY STACKED. A COLD FRONT EXTENDED FROM THE LOW TO THE SOUTHEAST OVER EASTERN KY...WITH AN ASSOCIATED TROF APPROACHING THE MISSISSIPPI RIVER. REG RADAR LOOP SHOWS SCATTERED LIGHT SHOWERS ROTATING AROUND THE LOW...ACROSS THE MOST OF THE FA. VIS SAT LOOP INDICATES SOME EASTWARD PROGRESS OF THE LOWS WITH THE TRAILING EDGE OF THE CLOUDS ALONG A LINE FROM THE BOOTHEEL THROUGH SGF TO KC. LDS CHART SHOWS NO CLOUD TO GROUND STRIKES OVER THE ENTIRE REGIONAL VIEW. BOTH THE 00Z AND 12Z SAT RUN OF THE NAM SHOW PRECIP OUT OF FA BY 00Z SUN. THE 14Z RUN OF THE RUC ALSO SUGGESTS A SIMILAR SCENARIO. THE 12Z SAT RUN OF THE GFS...INDICATES A FEW HUNDREDTHS IN THE EVV TO HOP CORRIDOR AS DOES THE 12Z SAT ECMWF...WITH THIS IN MIND WILL KEEP AT LEAST A SMALL CHANCE IN EXTREME EAST AFTER 00Z SUN AND MONITOR LATEST RADAR LOOP FOR EXACT CUTOFF LOCATION OF POPS...CLOSER TO PRESS TIME OF COURSE. WILL KEEP THINGS DRY SUNDAY AND MONDAY AS MODEL CONSENSUS IS ADVERTISING FOR THE MOST PART. THE LATEST 12Z MODEL RUNS ALSO SUGGEST THAT ANY PRECIP MONDAY NIGHT WOULD LIKELY BE LATE AND CONFINED TO THE WESTERN HALF SO HAVE ADJUSTED GRIDS TO REFLECT THE AFOREMENTIONED. ALTHOUGH THE MODELS ARE IN PRETTY GOOD AGREEMENT OF BRINGING NEG SFC LI`S TO THE REGION MONDAY NIGHT THE BEST MOISTURE DOES NOT ARRIVE TIL LATE AND MAINLY OVER THE WEST. SO HAVE LEFT POPS IN ALL NIGHT BUT TWEAKED THE COVERAGE TO THE WEST HALF. ATMOSPHERE REMAINS UNSTABLE THROUGH TUESDAY NIGHT SO WILL MAINTAIN THUNDER. CAPE VALUES SOAR INTO THE 2000 J/KG DURING THE DAY TUESDAY SO THAT WILL BE THE BEST CHANCE OF THUNDER COVERAGE. ALTHOUGH CAPE DROPS OFF A GREAT DEAL TUESDAY NIGHT BUT STILL REMAINS IN THE 200 J/KG WITH NEG LI`S. THIS COMBINED WITH FRONT BISECTING THE ARE...WILL ALSO CONTINUE THUNDER. IN ADDITION IF THE 12Z GFS CAPES ARE CORRECT MIGHT BE A CHANCE OF ACTIVE WEATHER TUESDAY...WILL MONITOR FOR SUCCESSIVE MODEL RUNS FOR POSSIBLE STRONG THUNDERSTORMS TUESDAY INTO TUESDAY EVENING. AS FOR SKY COVER BEGAN CLEARING LATE TODAY OVER SEMO AND SLOWLY SPREAD CLEARING EASTWARD TO THE EVV AREA AROUND SUNRISE SUNDAY. AS FOR TEMPS ONLY MINOR TWEAKS TO REFLECT LATEST GUIDANCE TRENDS. .LONG TERM... /WEDNESDAY THROUGH SATURDAY/ IN THE MEDIUM RANGE PERIOD...THE 00Z ECMWF AND ITS ENSEMBLE MEAN ARE FAVORED BY HPC AND WILL BE FOLLOWED CLOSELY FOR THIS FORECAST. THIS RESULTS IN SOME SIGNIFICANT DEVIATIONS FROM THE 06Z AND 12Z GFS. THE GFS SOLUTION IS MUCH MORE PROGRESSIVE IN GENERAL...ADVERTISING COLD FRONT PASSAGES EARLY WEDNESDAY AND EARLY FRIDAY. A PATTERN SHIFT TO MORE OF A WESTERN TROUGH/EASTERN RIDGE REGIME IS FAVORED...WHICH LEADS TO A LESS ROBUST FRONTAL PASSAGE WEDNESDAY...AND A SLOWER ARRIVAL TO THE NEXT FRONT NOW FORECAST FOR LATE SATURDAY. FOLLOWING THE ECMWF SOLUTION RESULTS IN 20-30 POPS THROUGHOUT THE PERIOD WEDNESDAY THROUGH SATURDAY. IN GENERAL...HAVE 30S WITH THE WARM FRONT THURSDAY AND THE COLD FRONT SATURDAY...AND 20S WHEN WE ARE IN THE WARM SECTOR THURSDAY NIGHT THROUGH EARLY SATURDAY. WITH THE MID/UPPER LEVEL RIDGING THROUGH THE REGION...TEMPERATURES WILL REMAIN MILD THROUGH THE PERIOD. HIGHS WILL GENERALLY BE IN THE 70S WITH LOWS IN THE 50S EACH DAY. && .AVIATION... MVFR CONDITIONS IN SCATTERED SHOWERS WILL PERSIST FOR MUCH OF THE AFTERNOON...MAINLY ACROSS SOUTHERN ILLINOIS AND THE EVANSVILLE TRI STATE AREA. SKIES SHOULD CLEAR OUT OVER THE SOUTHWEST HALF OF THE AREA EARLY THIS EVENING...AND AS WINDS GO CALM...FOG DEVELOPMENT WILL BE LIKELY...WITH SOME AREAS LIKE KCGI POSSIBLY BECOMING LOCALLY DENSE. IN THE KEVV AND KOWB AREAS...MVFR TO LOW VFR CEILINGS ARE EXPECTED TO CONTINUE THROUGHOUT THE 18Z TAF PERIOD. THERE WILL BE A BREAK IN THE SHOWERY PRECIPITATION FROM LATE AFTERNOON TO LATE EVENING...BUT ANOTHER ROUND OF SHOWERS WITH MVFR CONDITIONS WILL BE POSSIBLE FROM 06Z-15Z. IN THE NORTHEAST...WINDS WILL WAFFLE 20-30 DEGREES OR SO EITHER SIDE OF DUE WEST THROUGHOUT THE PERIOD. && .PAH WATCHES/WARNINGS/ADVISORIES... KY...NONE. MO...NONE. IL...NONE. IN...NONE. && $$ KH/DS ky AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WAKEFIELD VA 805 PM EDT SUN APR 20 2008 .SYNOPSIS... A BROAD AREA OF LOW PRESSURE TRACKS SLOWLY ACROSS THE REGION TONIGHT AND MONDAY...AND PUSHES OFF THE NORTH CAROLINA COAST BY TUESDAY. HIGH PRESSURE BUILDS SOUTHWARD ACROSS THE MID ATLANTIC REGION WEDNESDAY INTO FRIDAY. && .NEAR TERM /UNTIL 6 AM MONDAY MORNING/... ENSEMBLE OF SHORT TERMS MODELS (RUC/NAM/GFS) HAVE HANDLED THE HEAVY PCPN BANDS ACROSS OUR FCST FAIRLY WELL UP TO THIS POINT. A MORE WIDESPREAD AXIS OF HEAVIER RAIN EARLIER THIS AM... COINCIDING WITH THE HIGHER CLOUD TOPS/DEEPER CONVECTION ORIGINATING FROM THE LOWER PTN OF THE GULF STREAM E OF THE FL PENINSULA. CLOUD TOPS HAVE WARMED (LOWERED) DURING THE AFTN HOURS AS THIS WARM CONVEYOR BELT CURVED AND SHIFTED FARTHER OFFSHORE... LIKELY DUE TO SOME DEGREE THE LOSS OF THE NOCTURNAL LLJ AND ONSET OF DIFFERENTIAL DAYTIME HEATING. RADAR TRENDS INDICATE LESS NUMEROUS CLUSTERS OF CONVECTION...HOWEVER MAIN CONCENTRATION REMAINS ALONG THE I-95 CORRIDOR. ISOLATED SVR WX WILL REMAIN POSSIBLE... AS FAVORABLE LLVL THERMODYNAMICS (THETA-E ADVECTION) COINCIDES WITH RELATIVELY STRONG MID LEVEL LAPSE RATES (7 TO 7.5 C/KM BTWN 700-500 MB)...AS THE COLD CORE/DRIER AIR ALOFT ADVECTS E-NE-N FROM THE BASE OF THE UPPER LOW AND INTO THE FCST AREA. EXPECT THE MAIN BAND(S) OF DEEPER CONVECTION TO SHIFT FROM N-S TO A MORE NW-SE ORIENTATION OVERNIGHT...WITH THE HEAVIEST RAINFALL POTENTIAL BASICALLY ALON AND S OF THE I-64 CORRIDOR. LOSS OF DIURNAL EFFECTS (DIFFERENTIAL SFC HEATING) WOULD SUGGEST A DIMINISHING TREND...HOWEVER PER RUC/NAM/GFS PROGS...DEVELOPMENT OF SUBTLE LLJ (25-30+ KTS BTWN 950-850 MB) WOULD SUPPORT FURTHER DEVELOPMENT AND PERSISTENCE OF CONVECTION. FOR NOW...HAVE OPTED NOT TO EXTEND THE CURRENT FLASH FLOOD WATCH AS BELIEVE THE REGION(S) OF HEAVIEST RAIN WILL BE SHIFTING OVERNIGHT (ALBEIT SLOWLY). && .SHORT TERM /6 AM MONDAY MORNING THROUGH TUESDAY NIGHT/... EXTENSIVE CLOUDS AND RAIN CHANCES CONTINUE MONDAY AS THE LOW SLOWLY PIVOTS TO THE CAROLINA COAST. KEPT HIGH (>50%) POPS IN ALL AREAS...WITH THE HEAVIEST RAIN EXPECTED OVER SC/SERN VA AND NERN NC...WHERE BEST QG FORCING AND LLVL THERMODYNAMICS ARE EXPECTED TO BE). THE PATTERN IS EXPECTED TO TRANSITION VERY SLOWLY MON NIGHT AND TUE... AS THE LOW MOVES SLOWLY SE AND EVENTUALLY OFF THE SE COAST. WHILE EXPECT RAIN CHANCES TO DIMINISH PER WEAKENING DYNAMICS...CONTINUED DEEP E TO EVENTUALLY NE FLOW WILL MAINTAIN EXTENSIVE MOISTURE ACROSS THE FCST AREA...PARTICULARLY AT LOW LEVELS. CONTINUED WITH FCST TEMPS COOLER THAN MOS GUIDANCE ON TUE IN LIGHT OF THE ANTICIPATED MAINLY CLOUDY CONDITIONS WITH SCATTERED SHOWERS. && .LONG TERM /WEDNESDAY THROUGH SUNDAY/... LATEST 12Z RUNS OF THE GFS AND ECMWF REMAIN IN FAIRLY GOOD AGREEMENT WITH THE OVERALL PATTERN...UPR LOW DRIFTS WELL OFF TO THE ESE TUE NGT/ERLY WED. HOWEVER...MODEL SNDGS SHOW PLENTY OF LOW LVL MSTR REMAINING IN PLACE AS OF 12Z WED...AND GNLY THESE AMPLIFIED FEATURES TAKE LONGER THAN MODELS THINK TO LEAVE THE REGION. HAVE UNDERCUT MOS FOR HIGHS BY ABOUT 2-3 DEGREES ON WED (MORE ON THE COAST)...AND HAVE RETAINED A 20% CHC FOR -RA IN THE SOUTHEAST. GRADUAL IMPROVEMENT THROUGH THE WEEK AS UPR RIDGE AXIS MOVES FROM THE TN/OH VALLEY THU...AND ALONG THE SPINE OF THE APPALACHIANS BY FRI. TRENDS STILL DO NOT SHOW THE RIDGE AXIS MOVING TOO FAR NEWD INTO NEW ENGLND/ERN CANADA...SO WE SHOULD HAVE DRY CONDITIONS LATER WED AFTN INTO FRI AS SFC HIGH NOSES DOWN ALONG THE EAST COAST. TEMPS RISE WELL INTO THE 70S THU/FRI EXCEPT FOR COOLER CONDITIONS ALONG THE IMMEDIATE COASTAL ZONES WITH CONTINUED EASTERLY LOW LVL FLOW. RIDGING BREAKS DOWN FRI NGT/SAT IN RESPONSE TO ANOTHER DEEP TROUGH/CUTOFF LOW MVG INTO THE GRT LAKES. HAVE BROADBRUSHED ENTIRE AREA W/ 30% POPS FOR SHWRS/TSTMS SAT. KEEPING SUNDAY DRY AT THIS PT AS FRONT MOVES SE AND OFF THE COAST. && .AVIATION /00Z MONDAY THROUGH FRIDAY/... IFR CONDS WITH HEAVY THUNDERSTORMS CURRENTLY STRETCHING ALONG AND EAST OF I-95...INCLUDING RIC...TO PERSIST FOR THIS AREA AT LEAST ON A PERIODIC BASIS THRU 02Z...MOSTLY MVFR AFTER THRU 06Z. OTHER SITES...SCT SHRA WITH ISOL EMBEDDED TSRA WITH MVFR CONDS THROUGH 06Z. AFTER 06Z...XPCT CIGS TO DESCEND TO IFR AND VSBYS REDUCED TO IFR LATE TONIGHT WITH SHRA AND BR CONTINUING INTO MONDAY. FOR MONDAY...LATEST GUIDANCE SUGGESTING IFR/MVFR CIGS / MVFR VSBYS ACROSS AREA AS WINDS SHIFT TO EAST/ONSHORE FLOW. ONSHORE FLOW (E/NE) CONT THRU AT LEAST TUES NIGHT...THEREFORE IMPRVMNT TO AVN CONDS SLO TOWARDS MIDWEEK AS UPR LVL LO PRES SLIDES AWAY FM RGN. && .MARINE... TORNADO WATCH FOR CHES BAY THROUGH 05Z. XPCT DVLPMENT OF STORMS IN THE AREA OVER THE NEXT FEW HOURS. SCA FLAGS WILL BE IN EFFECT FOR ALL ZONES BEGINNING THIS EVENG. ON COASTAL WATERS...SEAS HAVE SLOWLY COME UP WITH BUOY 44009 REACHING 5 FT AT 23Z...XPCT TO 4-5 FT LATER THIS EVENG (CURRENTLY SEAS ARE RUNNING ARND 3 FT). THEREAFTER...PERSISTENT EASTERLY FLOW MON/TUE WILL ALLOW SEAS TO BUILD SIGNIFICANTLY...ESPECIALLY ACRS NRN COASTAL WTRS. POSITION OF SFC HIGH ACRS NEW ENGLAND STILL SUGGESTS GOING WITH A BIT MORE WIND THAN MODELS ARE CURRENTLY SHOWING...MAINLY 20-25 KTS W/ GUSTS TO 30 KT AND SEAS COMING UP TO 9 FT NRN CSTL WTRS...6-8 FT ACRS SOUTH WHERE TRACK OF THE LOW MAY KEEP WINDS A BIT LOWER. EXPECT SEAS TO REMAIN ABOVE 5 FT THROUGH AT LEAST WED NGT...AND FOR NOW HAVE EXTENDED THE SCA HEADLINES THRU 22Z TUE. TIDES... TOO EARLY AT THIS POINT FOR ANY TIDAL FLOODING PRODUCTS...AT THIS PT LOOKING TO BE 1 FOOT ANOMALIES MON NGT/TUE...ESP ACRS SRN BAY/AND CSTL WTRS. && .AKQ WATCHES/WARNINGS/ADVISORIES... MD...NONE. NC...FLASH FLOOD WATCH UNTIL MIDNIGHT EDT TONIGHT FOR NCZ012-013- 030. VA...FLASH FLOOD WATCH UNTIL MIDNIGHT EDT TONIGHT FOR VAZ048-049- 061>064-067>076-079>083-087>090-092. MARINE...SMALL CRAFT ADVISORY UNTIL 6 PM EDT TUESDAY FOR ANZ630>633-650- 652-654-656-658. && $$ SYNOPSIS...BKH NEAR TERM...BKH SHORT TERM...BKH LONG TERM...LKB AVIATION...BAJ MARINE...LKB/BAJ md AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GAYLORD MI 929 PM EDT SUN APR 20 2008 .UPDATE...AN UNEVENTFUL EVENING. WE FINALLY MANAGED TO SQUEEZE OUT SOME LATE AFTERNOON CU FROM GRAYLING/HTL WESTWARD...BUT NO SHOWERS. SKIES HAVE GONE MOSTLY CLEAR OVER NW/N CENTRAL LOWER MI...AND PARTS OF EASTERN UPPER. THERE IS ANOTHER BATCH OF MID AND HIGH CLOUDS ROTATING BACK ACROSS LAKE HURON...AND WILL ADJUST CLOUD GRIDS TO ACCOUNT FOR THIS. HOWEVER...THE UPPER LOW TO OUR SE IS ABOUT TO LOSE ITS INFLUENCE. UPPER RIDGING OVER THE NORTHERN/WESTERN LAKES WILL SLIDE SE...AS A REX BLOCK FORMS OVER THE EAST COAST. CIRRUS WILL STOP ITS INROADS AS THE UPPER RIDGE AXIS GRADUALLY SLIDES TO OUR SE...LATE TONIGHT AND ESPECIALLY DURING THE DAY ON MONDAY. LOW LEVELS AREN/T QUITE AS DRY AS THE LAST TWO DAYS...AND WE/LL SEE AN INCREASING CLOUD TREND FOR AT LEAST THE EARLY PART OF THE NIGHT. MIN TEMPS SHOULD BE NEAR OR SOMEWHAT WARMER THAN READINGS THE LAST FEW NIGHTS. ZOLTOWSKI && .AVIATION...WILL SEE SCT MID CLOUDS ROTATE BACK INTO THE REGION TONIGHT...AROUND NW FLANK OF UPPER DISTURBANCE NOW IN THE MID ATLANTIC STATES. LOW LEVEL WINDS WILL TURN MORE SOUTHERLY MONDAY AS THAT SYSTEM DEPARTS...ALLOWING LOWER LEVEL MOISTURE TO RETURN NORTHWARD IN NW AND N CENTRAL LOWER MI MONDAY. THIS SHOULD RESULT IN A 5-6K FOOT CLOUD DECK AT TIMES FOR PLN/TVC...ESPECIALLY MONDAY AFTERNOON. CONDITIONS STILL VFR THRU THE FORECAST. JZ && .PREV DISCUSSION...ISSUED 316 PM SUN APR 20... LATEST RUC ANALYSIS AND VIS/IR/WV/RADAR IMAGERY SHOW THE UPPER LEVEL FLOW CONTINUING TO BE DOMINATED BY THE CLOSED LOW OVER THE APPALACHIANS WHICH IS UNDERCUTTING A BROAD RIDGE OVER THE CENTRAL NOAM. MID-UPPER LEVEL CLOUDS WITHIN A DEFORMATION ZONE ACROSS THE UPPER PENINSULA HAVE BEEN SLOWING LIFTING NORTH LEAVING ALL OF NORTHERN MICHIGAN UNDER SUNNY OR MOSTLY SUNNY SKIES. AMPLE SUNSHINE COMBINED WITH THE LATE APRIL SUN HAVE HELPED TEMPERATURES RISE INTO THE MID TO UPPER 70S AWAY FROM THE GREAT LAKES WITH EVEN SOME REPORTS OF LOW 80S AROUND WELLSTON/PRUDENVILLE/BELLAIRE. RH LEVELS OVER THE HIGHER TERRAIN HAVENT DROPPED QUITE AS LOW AS EXPECTED YET...AND REMAIN BETWEEN 27-32F. MEANWHILE...ON THE NORTHEAST FLANK OF THE UPPER LOW...DEEP MOISTURE PLUME IS ROTATING NE TOWARDS LAKE ERIE BUT IS HAVING TROUBLE PENETRATING A VERY DRY AIRMASS ACROSS LOWER MICHIGAN. CLOUDS AND TEMPS REMAIN THE PRIMARY FORECAST CONCERNS THROUGH TOMORROW. TONIGHT...UNDERCUTTING UPPER LOW WILL SPIN TOWARDS THE MID-ATLANTIC COAST WHILE A SLIGHT INCREASE IN MID-LEVEL HEIGHTS OCCURS OVER THE GREAT LAKES. LOW-MID LEVEL MOISTURE PLUME ROTATING AROUND THE UPPER LOW WILL PIVOT NORTHWEST TOWARDS LAKE HURON AND NE LOWER/EASTERN UPPER TONIGHT. MODELS INDICATE TO VARIOUS DEGREES THAT THE MOISTURE PLUME FALLS APART AS IT REACHES NORTHERN MICHIGAN. THE GFS IS LESS AGGRESSIVE THAN THE NAM IN THIS REGARD...AND THINK THAT THE NAM IS THE BETTER WAY TO GO GIVEN THE VERY DRY AIRMASS IN PLACE. WILL INCREASE CLOUD COVER OVER EASTERN AND NORTHERN SECTIONS OF THE CWA TONIGHT...BUT WILL KEEP ONLY PARTLY CLOUDY SKIES IN THE FORECAST. LOWS GENERALLY IN THE 40S. TOMORROW...ANOTHER PLEASANT SPRING DAY IN STORE FOR NORTHERN MICHIGAN. A SMATTERING OF LOW-MID CLOUDS TO START THE MORNING WILL EVOLVE INTO A DIURNAL CU FIELD OVER INLAND AREAS FOR THE AFTERNOON. ANY CU THAT DOES DEVELOP LOOKS TO BE LIMITED BY A MID-LEVEL CAP BETWEEN 600-700MB. THIS CAP LOOKS POTENT ENOUGH TO KEEP A DRY FORECAST IN PLACE DESPITE A MORE MOIST PROFILE THAN TODAY AND LOCALIZED CONVERGENCE ALONG LAKE BREEZES ACROSS NW LOWER WITH THE PREVALENT NE FLOW. HOWEVER...IF HIGHER DEWPOINTS INTO THE UPPER 40S MATERIALIZE...THEN CHANCES FOR A SHOWER WILL INCREASE ALONG THE LAKE BREEZE. HIGHS SLIGHTLY COOLER IN THE UPPER 60S/LOW 70S AWAY FROM THE LAKES. MPC MON NIGHT THRU WED...PRIMARY FCST CONCERN REMAINS PRECIP CHANCES TUE AFTN/NIGHT ALONG WITH TEMPS. GUIDANCE REMAINS IN GOOD AGREEMENT WITH LARGE GYRE ACRS THE PACIFIC NORTHWEST OPENING UP THRU MON AFTN AS ADDITIONAL PACIFIC ENERGY BRIEFLY UNDERCUTS BLOCKING RIDGE INTO ALASKA...WITH REMNANT ENERGY SHEARING OUT THRU THE UPPER MIDWEST TUE AFTN/EVENING. ASSOCIATED SFC COLD FRONT STILL ON TRACK TO PUSH THRU THE REGION BETWEEN 00Z AND 12Z WED...WITH OBVIOUS INCREASING THREAT FOR PRECIP DURING THIS TIME. STILL APPEARS QG SUPPORT WILL SLIP NORTH OF THE REGION...THOUGH WITH DECENT MOISTURE TAP PER WIDE OPEN WESTERN GULF AND MODEST SFC-700MB CONVERGENCE ALONG INCOMING BOUNDARY...LIKELY POPS WARRANTED AT THIS TIME...IN LINE WITH PERSISTENT TREND OF OPERATIONAL AND ENSEMBLE GUIDANCE. BIGGEST QUESTION REMAINS WHAT WILL HAPPEN AHEAD OF THE FRONT...AS APPEARS DECENT HEATING LIKELY TO TAKE SHAPE IN THE THERMAL RIDGE (HIGHS UPR 60S TO MID 70S) TUE AFTN...WHILE SFC-850MB THETA-E RIDGE BUILDS INTO THE AREA. COUPLED WITH WEAKLY UPSLOPE REGIME PER BACKING OF LOW LEVEL FLOW AHEAD OF INCOMING FRONT...AS WELL AS MODEL HINTS OF ENHANCED CONVERGENCE ALONG DEVELOPING PRE-FRONTAL TROUGH...DIFFICULT TO RULE OUT SCATTERED CONVECTION FIRING ACRS THE WESTERN CWA. FCST RAOBS WITH A 72/48 PARCEL (WHICH SHOULD BE ACHIEVABLE) YIELD 200-300 J/KG MLCAPE...THOUGH ARGUABLY GUIDANCE MAY BE OVERDOING MOISTURE JUST A TAD. IN EITHER CASE...CHANCY POPS CERTAINLY WARRANTED... ESPECIALLY WITH LATEST TREND FOR GUIDANCE TO SPEED UP TIMING OF ENTIRE SYSTEM. SHOULD SEE A QUICK END TO PRECIP BY SUNRISE WED AS LOW/MID LEVEL RIDGING QUICKLY TAKE HOLD...WITH RAPID CLEARING IN THE WAKE OF FROPA WITH 1000-500MB RH FALLING OFF THE TABLE TO AROUND 25% VIA STRONG SUBSIDENCE. COOLER READINGS IN THE MID 50S TO MID 60S WARRANTED FOR WED AFTN WITH QUICK SHOT OF COLD ADVECTION (H85 TEMPS DIP TO AROUND 3-5C PER GEFS MEAN - OPERATIONAL GFS WAY TOO COOL)...THOUGH LIKELY OFFSET BY INSOLATION OUTSIDE OF PERHAPS AFTN CU GIVEN THERMAL TROUGH OVERHEAD. LATER PERIODS (WED NIGHT THRU SUN)...RATHER BLOCKY PATTERN TO PERSIST THRU THE PERIOD...WITH HIGHLY AMPLIFIED/CLOSED MID LEVEL RIDGING ACRS ALASKA FAVORING DOWNSTREAM TROUGHING OVR CENTRAL CANADA...WITH AN EXTENSION INTO THE NORTHERN CONUS. MEDIUM RANGE GUIDANCE REMAINS IN GOOD AGREEMENT WITH THIS OVERALL SETUP...THOUGH SOME DIFFERENCES REMAIN WITH DEGREE OF AMPLIFICATION OF THE WESTERN CONUS TROUGH. STILL APPEARS A NICE DAY ON TAP FOR THU AS LOW/MID LEVEL RIDGE AND ASSOCIATED SUBSIDENCE/DRYING BUILDS OVERHEAD IN THE WAKE OF FRONTAL PASSAGE. SHOULD END UP BEING A RATHER SUNNY DAY...OUTSIDE OF SOME POTENTIAL INCREASE IN JET-DRIVEN CIRRUS BY AFTN...WITH GUIDANCE NUMBERS STILL APPEARING TO BE JUST A TOUCH TOO COOL GIVEN EXPECTED INSOLATION. THEREAFTER...INCREASING PRECIP CHANCES IN ORDER FRI/SAT TIMEFRAME AS ENERGY UNDERCUTTING PACIFIC BLOCKING RIDGE AIDS IN KICKING WESTERN TROUGH EASTWARD...WITH ASSOCIATED LEE CYCLONE DEVELOPMENT/SFC FRONTOGENESIS TAKING PLACE ACRS THE PLAINS BEFORE MAKING A RUN TOWARD THE NORTHERN LAKES. POTENTIAL FOR ANOTHER QUITE WARM DAY ON FRI WITH REGION FALLING IN THE THERMAL RIDGE AHEAD OF APPROACHING FRONT...AND HAVE THUS GONE ABOVE GUIDANCE ONCE AGAIN. ALSO SOME POTENTIAL FOR THUNDER WITH INCOMING FRONT...THOUGH WILL HOLD OFF ON MENTION AT THIS TIME WITH SOME REMAINING TIMING ISSUES. LAWRENCE && .APX WATCHES/WARNINGS/ADVISORIES... MI...NONE. LM...NONE. LH...NONE. LS...NONE. && $$ mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GAYLORD MI 733 PM EDT SUN APR 20 2008 .AVIATION...WILL SEE SCT MID CLOUDS ROTATE BACK INTO THE REGION TONIGHT...AROUND NW FLANK OF UPPER DISTURBANCE NOW IN THE MID ATLANTIC STATES. LOW LEVEL WINDS WILL TURN MORE SOUTHERLY MONDAY AS THAT SYSTEM DEPARTS...ALLOWING LOWER LEVEL MOISTURE TO RETURN NORTHWARD IN NW AND N CENTRAL LOWER MI MONDAY. THIS SHOULD RESULT IN A 5-6K FOOT CLOUD DECK AT TIMES FOR PLN/TVC...ESPECIALLY MONDAY AFTERNOON. CONDITIONS STILL VFR THRU THE FORECAST. JZ && .DISCUSSION...ISSUED 316 PM SUN APR 20... LATEST RUC ANALYSIS AND VIS/IR/WV/RADAR IMAGERY SHOW THE UPPER LEVEL FLOW CONTINUING TO BE DOMINATED BY THE CLOSED LOW OVER THE APPALACHIANS WHICH IS UNDERCUTTING A BROAD RIDGE OVER THE CENTRAL NOAM. MID-UPPER LEVEL CLOUDS WITHIN A DEFORMATION ZONE ACROSS THE UPPER PENINSULA HAVE BEEN SLOWING LIFTING NORTH LEAVING ALL OF NORTHERN MICHIGAN UNDER SUNNY OR MOSTLY SUNNY SKIES. AMPLE SUNSHINE COMBINED WITH THE LATE APRIL SUN HAVE HELPED TEMPERATURES RISE INTO THE MID TO UPPER 70S AWAY FROM THE GREAT LAKES WITH EVEN SOME REPORTS OF LOW 80S AROUND WELLSTON/PRUDENVILLE/BELLAIRE. RH LEVELS OVER THE HIGHER TERRAIN HAVENT DROPPED QUITE AS LOW AS EXPECTED YET...AND REMAIN BETWEEN 27-32F. MEANWHILE...ON THE NORTHEAST FLANK OF THE UPPER LOW...DEEP MOISTURE PLUME IS ROTATING NE TOWARDS LAKE ERIE BUT IS HAVING TROUBLE PENETRATING A VERY DRY AIRMASS ACROSS LOWER MICHIGAN. CLOUDS AND TEMPS REMAIN THE PRIMARY FORECAST CONCERNS THROUGH TOMORROW. TONIGHT...UNDERCUTTING UPPER LOW WILL SPIN TOWARDS THE MID-ATLANTIC COAST WHILE A SLIGHT INCREASE IN MID-LEVEL HEIGHTS OCCURS OVER THE GREAT LAKES. LOW-MID LEVEL MOISTURE PLUME ROTATING AROUND THE UPPER LOW WILL PIVOT NORTHWEST TOWARDS LAKE HURON AND NE LOWER/EASTERN UPPER TONIGHT. MODELS INDICATE TO VARIOUS DEGREES THAT THE MOISTURE PLUME FALLS APART AS IT REACHES NORTHERN MICHIGAN. THE GFS IS LESS AGGRESSIVE THAN THE NAM IN THIS REGARD...AND THINK THAT THE NAM IS THE BETTER WAY TO GO GIVEN THE VERY DRY AIRMASS IN PLACE. WILL INCREASE CLOUD COVER OVER EASTERN AND NORTHERN SECTIONS OF THE CWA TONIGHT...BUT WILL KEEP ONLY PARTLY CLOUDY SKIES IN THE FORECAST. LOWS GENERALLY IN THE 40S. TOMORROW...ANOTHER PLEASANT SPRING DAY IN STORE FOR NORTHERN MICHIGAN. A SMATTERING OF LOW-MID CLOUDS TO START THE MORNING WILL EVOLVE INTO A DIURNAL CU FIELD OVER INLAND AREAS FOR THE AFTERNOON. ANY CU THAT DOES DEVELOP LOOKS TO BE LIMITED BY A MID-LEVEL CAP BETWEEN 600-700MB. THIS CAP LOOKS POTENT ENOUGH TO KEEP A DRY FORECAST IN PLACE DESPITE A MORE MOIST PROFILE THAN TODAY AND LOCALIZED CONVERGENCE ALONG LAKE BREEZES ACROSS NW LOWER WITH THE PREVALENT NE FLOW. HOWEVER...IF HIGHER DEWPOINTS INTO THE UPPER 40S MATERIALIZE...THEN CHANCES FOR A SHOWER WILL INCREASE ALONG THE LAKE BREEZE. HIGHS SLIGHTLY COOLER IN THE UPPER 60S/LOW 70S AWAY FROM THE LAKES. MPC MON NIGHT THRU WED...PRIMARY FCST CONCERN REMAINS PRECIP CHANCES TUE AFTN/NIGHT ALONG WITH TEMPS. GUIDANCE REMAINS IN GOOD AGREEMENT WITH LARGE GYRE ACRS THE PACIFIC NORTHWEST OPENING UP THRU MON AFTN AS ADDITIONAL PACIFIC ENERGY BRIEFLY UNDERCUTS BLOCKING RIDGE INTO ALASKA...WITH REMNANT ENERGY SHEARING OUT THRU THE UPPER MIDWEST TUE AFTN/EVENING. ASSOCIATED SFC COLD FRONT STILL ON TRACK TO PUSH THRU THE REGION BETWEEN 00Z AND 12Z WED...WITH OBVIOUS INCREASING THREAT FOR PRECIP DURING THIS TIME. STILL APPEARS QG SUPPORT WILL SLIP NORTH OF THE REGION...THOUGH WITH DECENT MOISTURE TAP PER WIDE OPEN WESTERN GULF AND MODEST SFC-700MB CONVERGENCE ALONG INCOMING BOUNDARY...LIKELY POPS WARRANTED AT THIS TIME...IN LINE WITH PERSISTENT TREND OF OPERATIONAL AND ENSEMBLE GUIDANCE. BIGGEST QUESTION REMAINS WHAT WILL HAPPEN AHEAD OF THE FRONT...AS APPEARS DECENT HEATING LIKELY TO TAKE SHAPE IN THE THERMAL RIDGE (HIGHS UPR 60S TO MID 70S) TUE AFTN...WHILE SFC-850MB THETA-E RIDGE BUILDS INTO THE AREA. COUPLED WITH WEAKLY UPSLOPE REGIME PER BACKING OF LOW LEVEL FLOW AHEAD OF INCOMING FRONT...AS WELL AS MODEL HINTS OF ENHANCED CONVERGENCE ALONG DEVELOPING PRE-FRONTAL TROUGH...DIFFICULT TO RULE OUT SCATTERED CONVECTION FIRING ACRS THE WESTERN CWA. FCST RAOBS WITH A 72/48 PARCEL (WHICH SHOULD BE ACHIEVABLE) YIELD 200-300 J/KG MLCAPE...THOUGH ARGUABLY GUIDANCE MAY BE OVERDOING MOISTURE JUST A TAD. IN EITHER CASE...CHANCY POPS CERTAINLY WARRANTED... ESPECIALLY WITH LATEST TREND FOR GUIDANCE TO SPEED UP TIMING OF ENTIRE SYSTEM. SHOULD SEE A QUICK END TO PRECIP BY SUNRISE WED AS LOW/MID LEVEL RIDGING QUICKLY TAKE HOLD...WITH RAPID CLEARING IN THE WAKE OF FROPA WITH 1000-500MB RH FALLING OFF THE TABLE TO AROUND 25% VIA STRONG SUBSIDENCE. COOLER READINGS IN THE MID 50S TO MID 60S WARRANTED FOR WED AFTN WITH QUICK SHOT OF COLD ADVECTION (H85 TEMPS DIP TO AROUND 3-5C PER GEFS MEAN - OPERATIONAL GFS WAY TOO COOL)...THOUGH LIKELY OFFSET BY INSOLATION OUTSIDE OF PERHAPS AFTN CU GIVEN THERMAL TROUGH OVERHEAD. LATER PERIODS (WED NIGHT THRU SUN)...RATHER BLOCKY PATTERN TO PERSIST THRU THE PERIOD...WITH HIGHLY AMPLIFIED/CLOSED MID LEVEL RIDGING ACRS ALASKA FAVORING DOWNSTREAM TROUGHING OVR CENTRAL CANADA...WITH AN EXTENSION INTO THE NORTHERN CONUS. MEDIUM RANGE GUIDANCE REMAINS IN GOOD AGREEMENT WITH THIS OVERALL SETUP...THOUGH SOME DIFFERENCES REMAIN WITH DEGREE OF AMPLIFICATION OF THE WESTERN CONUS TROUGH. STILL APPEARS A NICE DAY ON TAP FOR THU AS LOW/MID LEVEL RIDGE AND ASSOCIATED SUBSIDENCE/DRYING BUILDS OVERHEAD IN THE WAKE OF FRONTAL PASSAGE. SHOULD END UP BEING A RATHER SUNNY DAY...OUTSIDE OF SOME POTENTIAL INCREASE IN JET-DRIVEN CIRRUS BY AFTN...WITH GUIDANCE NUMBERS STILL APPEARING TO BE JUST A TOUCH TOO COOL GIVEN EXPECTED INSOLATION. THEREAFTER...INCREASING PRECIP CHANCES IN ORDER FRI/SAT TIMEFRAME AS ENERGY UNDERCUTTING PACIFIC BLOCKING RIDGE AIDS IN KICKING WESTERN TROUGH EASTWARD...WITH ASSOCIATED LEE CYCLONE DEVELOPMENT/SFC FRONTOGENESIS TAKING PLACE ACRS THE PLAINS BEFORE MAKING A RUN TOWARD THE NORTHERN LAKES. POTENTIAL FOR ANOTHER QUITE WARM DAY ON FRI WITH REGION FALLING IN THE THERMAL RIDGE AHEAD OF APPROACHING FRONT...AND HAVE THUS GONE ABOVE GUIDANCE ONCE AGAIN. ALSO SOME POTENTIAL FOR THUNDER WITH INCOMING FRONT...THOUGH WILL HOLD OFF ON MENTION AT THIS TIME WITH SOME REMAINING TIMING ISSUES. LAWRENCE && .APX WATCHES/WARNINGS/ADVISORIES... MI...NONE. LM...NONE. LH...NONE. LS...NONE. && $$ mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GAYLORD MI 316 PM EDT SUN APR 20 2008 .DISCUSSION...LATEST RUC ANALYSIS AND VIS/IR/WV/RADAR IMAGERY SHOW THE UPPER LEVEL FLOW CONTINUING TO BE DOMINATED BY THE CLOSED LOW OVER THE APPALACHIANS WHICH IS UNDERCUTTING A BROAD RIDGE OVER THE CENTRAL NOAM. MID-UPPER LEVEL CLOUDS WITHIN A DEFORMATION ZONE ACROSS THE UPPER PENINSULA HAVE BEEN SLOWING LIFTING NORTH LEAVING ALL OF NORTHERN MICHIGAN UNDER SUNNY OR MOSTLY SUNNY SKIES. AMPLE SUNSHINE COMBINED WITH THE LATE APRIL SUN HAVE HELPED TEMPERATURES RISE INTO THE MID TO UPPER 70S AWAY FROM THE GREAT LAKES WITH EVEN SOME REPORTS OF LOW 80S AROUND WELLSTON/PRUDENVILLE/BELLAIRE. RH LEVELS OVER THE HIGHER TERRAIN HAVENT DROPPED QUITE AS LOW AS EXPECTED YET...AND REMAIN BETWEEN 27-32F. MEANWHILE...ON THE NORTHEAST FLANK OF THE UPPER LOW...DEEP MOISTURE PLUME IS ROTATING NE TOWARDS LAKE ERIE BUT IS HAVING TROUBLE PENETRATING A VERY DRY AIRMASS ACROSS LOWER MICHIGAN. CLOUDS AND TEMPS REMAIN THE PRIMARY FORECAST CONCERNS THROUGH TOMORROW. TONIGHT...UNDERCUTTING UPPER LOW WILL SPIN TOWARDS THE MID-ATLANTIC COAST WHILE A SLIGHT INCREASE IN MID-LEVEL HEIGHTS OCCURS OVER THE GREAT LAKES. LOW-MID LEVEL MOISTURE PLUME ROTATING AROUND THE UPPER LOW WILL PIVOT NORTHWEST TOWARDS LAKE HURON AND NE LOWER/EASTERN UPPER TONIGHT. MODELS INDICATE TO VARIOUS DEGREES THAT THE MOISTURE PLUME FALLS APART AS IT REACHES NORTHERN MICHIGAN. THE GFS IS LESS AGGRESSIVE THAN THE NAM IN THIS REGARD...AND THINK THAT THE NAM IS THE BETTER WAY TO GO GIVEN THE VERY DRY AIRMASS IN PLACE. WILL INCREASE CLOUD COVER OVER EASTERN AND NORTHERN SECTIONS OF THE CWA TONIGHT...BUT WILL KEEP ONLY PARTLY CLOUDY SKIES IN THE FORECAST. LOWS GENERALLY IN THE 40S. TOMORROW...ANOTHER PLEASANT SPRING DAY IN STORE FOR NORTHERN MICHIGAN. A SMATTERING OF LOW-MID CLOUDS TO START THE MORNING WILL EVOLVE INTO A DIURNAL CU FIELD OVER INLAND AREAS FOR THE AFTERNOON. ANY CU THAT DOES DEVELOP LOOKS TO BE LIMITED BY A MID-LEVEL CAP BETWEEN 600-700MB. THIS CAP LOOKS POTENT ENOUGH TO KEEP A DRY FORECAST IN PLACE DESPITE A MORE MOIST PROFILE THAN TODAY AND LOCALIZED CONVERGENCE ALONG LAKE BREEZES ACROSS NW LOWER WITH THE PREVALENT NE FLOW. HOWEVER...IF HIGHER DEWPOINTS INTO THE UPPER 40S MATERIALIZE...THEN CHANCES FOR A SHOWER WILL INCREASE ALONG THE LAKE BREEZE. HIGHS SLIGHTLY COOLER IN THE UPPER 60S/LOW 70S AWAY FROM THE LAKES. MPC MON NIGHT THRU WED...PRIMARY FCST CONCERN REMAINS PRECIP CHANCES TUE AFTN/NIGHT ALONG WITH TEMPS. GUIDANCE REMAINS IN GOOD AGREEMENT WITH LARGE GYRE ACRS THE PACIFIC NORTHWEST OPENING UP THRU MON AFTN AS ADDITIONAL PACIFIC ENERGY BRIEFLY UNDERCUTS BLOCKING RIDGE INTO ALASKA...WITH REMNANT ENERGY SHEARING OUT THRU THE UPPER MIDWEST TUE AFTN/EVENING. ASSOCIATED SFC COLD FRONT STILL ON TRACK TO PUSH THRU THE REGION BETWEEN 00Z AND 12Z WED...WITH OBVIOUS INCREASING THREAT FOR PRECIP DURING THIS TIME. STILL APPEARS QG SUPPORT WILL SLIP NORTH OF THE REGION...THOUGH WITH DECENT MOISTURE TAP PER WIDE OPEN WESTERN GULF AND MODEST SFC-700MB CONVERGENCE ALONG INCOMING BOUNDARY...LIKELY POPS WARRANTED AT THIS TIME...IN LINE WITH PERSISTENT TREND OF OPERATIONAL AND ENSEMBLE GUIDANCE. BIGGEST QUESTION REMAINS WHAT WILL HAPPEN AHEAD OF THE FRONT...AS APPEARS DECENT HEATING LIKELY TO TAKE SHAPE IN THE THERMAL RIDGE (HIGHS UPR 60S TO MID 70S) TUE AFTN...WHILE SFC-850MB THETA-E RIDGE BUILDS INTO THE AREA. COUPLED WITH WEAKLY UPSLOPE REGIME PER BACKING OF LOW LEVEL FLOW AHEAD OF INCOMING FRONT...AS WELL AS MODEL HINTS OF ENHANCED CONVERGENCE ALONG DEVELOPING PRE-FRONTAL TROUGH...DIFFICULT TO RULE OUT SCATTERED CONVECTION FIRING ACRS THE WESTERN CWA. FCST RAOBS WITH A 72/48 PARCEL (WHICH SHOULD BE ACHIEVABLE) YIELD 200-300 J/KG MLCAPE...THOUGH ARGUABLY GUIDANCE MAY BE OVERDOING MOISTURE JUST A TAD. IN EITHER CASE...CHANCY POPS CERTAINLY WARRANTED... ESPECIALLY WITH LATEST TREND FOR GUIDANCE TO SPEED UP TIMING OF ENTIRE SYSTEM. SHOULD SEE A QUICK END TO PRECIP BY SUNRISE WED AS LOW/MID LEVEL RIDGING QUICKLY TAKE HOLD...WITH RAPID CLEARING IN THE WAKE OF FROPA WITH 1000-500MB RH FALLING OFF THE TABLE TO AROUND 25% VIA STRONG SUBSIDENCE. COOLER READINGS IN THE MID 50S TO MID 60S WARRANTED FOR WED AFTN WITH QUICK SHOT OF COLD ADVECTION (H85 TEMPS DIP TO AROUND 3-5C PER GEFS MEAN - OPERATIONAL GFS WAY TOO COOL)...THOUGH LIKELY OFFSET BY INSOLATION OUTSIDE OF PERHAPS AFTN CU GIVEN THERMAL TROUGH OVERHEAD. LATER PERIODS (WED NIGHT THRU SUN)...RATHER BLOCKY PATTERN TO PERSIST THRU THE PERIOD...WITH HIGHLY AMPLIFIED/CLOSED MID LEVEL RIDGING ACRS ALASKA FAVORING DOWNSTREAM TROUGHING OVR CENTRAL CANADA...WITH AN EXTENSION INTO THE NORTHERN CONUS. MEDIUM RANGE GUIDANCE REMAINS IN GOOD AGREEMENT WITH THIS OVERALL SETUP...THOUGH SOME DIFFERENCES REMAIN WITH DEGREE OF AMPLIFICATION OF THE WESTERN CONUS TROUGH. STILL APPEARS A NICE DAY ON TAP FOR THU AS LOW/MID LEVEL RIDGE AND ASSOCIATED SUBSIDENCE/DRYING BUILDS OVERHEAD IN THE WAKE OF FRONTAL PASSAGE. SHOULD END UP BEING A RATHER SUNNY DAY...OUTSIDE OF SOME POTENTIAL INCREASE IN JET-DRIVEN CIRRUS BY AFTN...WITH GUIDANCE NUMBERS STILL APPEARING TO BE JUST A TOUCH TOO COOL GIVEN EXPECTED INSOLATION. THEREAFTER...INCREASING PRECIP CHANCES IN ORDER FRI/SAT TIMEFRAME AS ENERGY UNDERCUTTING PACIFIC BLOCKING RIDGE AIDS IN KICKING WESTERN TROUGH EASTWARD...WITH ASSOCIATED LEE CYCLONE DEVELOPMENT/SFC FRONTOGENESIS TAKING PLACE ACRS THE PLAINS BEFORE MAKING A RUN TOWARD THE NORTHERN LAKES. POTENTIAL FOR ANOTHER QUITE WARM DAY ON FRI WITH REGION FALLING IN THE THERMAL RIDGE AHEAD OF APPROACHING FRONT...AND HAVE THUS GONE ABOVE GUIDANCE ONCE AGAIN. ALSO SOME POTENTIAL FOR THUNDER WITH INCOMING FRONT...THOUGH WILL HOLD OFF ON MENTION AT THIS TIME WITH SOME REMAINING TIMING ISSUES. LAWRENCE && .AVIATION... /ISSUED 112 PM EDT SUN APR 20 2008/ HIGH CLOUDS WILL OCCASIONALLY DRIFT ACROSS THE TAF SITES THIS AFTERNOON. DEEPER MOISTURE WRAPPING AROUND LOW PRESSURE OVER THE APPALACHIANS WILL PINWHEEL NORTHWEST TOWARDS LAKE HURON TONIGHT. SOME 6-10KFT CLOUDS MAY REACH APN TONIGHT...BUT STILL SOME UNCERTAINTY ABOUT HOW FAR WEST THESE CLOUDS WILL MAKE IT. ANY CLOUDS WILL TRY TO EXIT TOMORROW MORNING. WILL KEEP VFR CONDITIONS PREVAILING THROUGH THE TAF PERIOD. MPC && .APX WATCHES/WARNINGS/ADVISORIES... MI...NONE. LM...NONE. LH...NONE. LS...NONE. && $$ mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI 329 AM EDT SUN APR 20 2008 .SHORT TERM...TODAY THE CENTER OF THE UPPER LEVEL CIRCULATION/LARGE CUTOFF LOW OVER EASTERN KENTUCKY EARLY THIS MORNING WILL CONTINUE TO SLOWLY TRACK OFF TO THE SOUTHEAST TODAY...AWAY FROM SOUTHERN LOWER MICHIGAN. THIS WILL RESULT IN SOME MID LEVEL WARMING/500 MB HEIGHT RISES...AS 500 MB TEMP IS FORECASTED TO RISE TO -15 C THIS AFTERNOON...UP FROM THE -19 C WHICH THE 00Z DTX RAOB INDICATED. MEANWHILE...DEEP EASTERLY FLOW IN THE LOW LEVELS WILL LEAD TO MODEST COLD AIR ADVECTION DURING THE DAY...AS 850 MB TEMPS FORECASTED TO DROP TO 8 TO 10 C BY 00Z MONDAY. WITH THE MID LEVEL WARMING AND LIMITED MOISTURE...THINKING SHOWERS ARE GOING TO BE HARD TO COME BY...AND CERTAINLY DON`T EXPECT ANY THUNDERSTORMS WITH LESS INSTABILITY TODAY. BASED ON THE BEST LOW LEVEL CONVERGENCE/MOISTURE POOLING...THINKING THE BEST CHANCE FOR SHOWERS WILL BE ACROSS LENAWEE/WASHTENAW COUNTIES. BUT EVEN THERE...DON`T SEE MUCH MORE THAN LOW CHANCE POPS. WITH RELATIVELY STABLE MARINE LAYER PUSH...PLANNING TO GO DRY/SLIGHT CHANCE POPS FOR THUMB REGION/NORTH HALF OF THE CWA. AS FAR AS TEMPERATURES GO...AFTER SUCCESSFULLY CHOOSING THE WARMER NAM TEMPS YESTERDAY...WILL CONTINUE TO TO LEAN TOWARD WARMER MAXES AS THERE SHOULD BE CONSIDERABLE INSOLATION...OFFSET BY THE PREVIOUSLY MENTIONED LOW LEVEL COLD ADVECTION AND MARINE LAYER. WITH THOSE CONSIDERATIONS...FORESEE MAXES PREDOMINATELY AROUND 70/LOWER 70S...EXCEPT MID 70S IN AND AROUND THE FLINT VICINITY. INTERESTING TO NOTE...TODAY WILL MARK THE 4TH CONSECUTIVE DAY FLINT`S MAX WILL EXCEED 70 DEGREES. THE AVERAGE NUMBER OF OCCURRENCES (MAX GREATER THAN 70 DEGREES) FOR THE MONTH OF APRIL IS 4...WITH THE RECORD BEING 11 DAYS (1977/1985). A LOOK AT THE FORECAST OVER THE NEXT COUPLE OF DAYS SHOWS SHOWS MAXES CONTINUING TO RISE ABOVE 70. SO...ALTHOUGH SOME MAY HAVE COMPLAINED SPRING ARRIVED A BIT LATE...WE CERTAINLY HAVE TURNED THINGS AROUND. && .LONG TERM...TONIGHT THROUGH SATURDAY AS UPPER LOW DRIFTS INTO THE MID ATLANTIC REGION... PRECIPITATION THREAT FOR SOUTHEAST MICHIGAN WILL DIMINISH TONIGHT AND CONTINUE THROUGH TUESDAY. GFS STILL HAS A LITTLE BIT OF CAPE EVIDENT OVER SOUTHWEST LOWER MONDAY AFTERNOON AND PARAMETERIZATIONS IMMEDIATELY KICK OFF A LARGE AREA OF QPF. OBVIOUSLY THINK THIS IS OVERDONE AND WILL KEEP MONDAY AFTERNOON DRY ACROSS THE AREA. MODELS ARE PRETTY CONSISTENT WITH TIMING OF NEXT FRONT INTO THE WESTERN GREAT LAKES ON TUESDAY ALTHOUGH GFS IS SLIGHTLY FASTER THAN THE NAM... BUT PRETTY CONSISTENT WITH PREVIOUS CYCLES. IN EITHER CASE... WILL KEEP CHANCE-TYPE POPS GOING TUESDAY NIGHT AND EARLY WEDNESDAY AS THE FRONT MOVES THROUGH. A LOT OF UNCERTAINLY REMAINS IN THE LATTER STAGES OF THE FORECAST. THE LAST THREE GFS CYCLES ARE ALL STICKING WITH A SIGNIFICANT SYSTEM MOVING INTO THE UPPER MIDWEST AND ONTARIO... BUT HAVE JUMPED THE MAIN SURFACE VALID 18UTC FRIDAY FROM UPPER MICHIGAN TO NEAR JAMES BAY AND NOW TO NORTHERN MINNESOTA. APPROACH OF SURFACE FRONT DURING THIS TIMEFRAME CERTAINLY SUPPRTIVE OF POPS FOR FRIDAY INTO SATURDAY... ALTHOUGH EXTENT OF PRECIPITATION IS STILL A LITTLE UP IN THE AIR. IF LATEST GFS CYCLE VERIFIES... EXPECT SIGNIFICANT NEGATIVE TILT TO UPPER TROUGH IN THE PLAINS BY FRIDAY WITH A CHANCE OF SEVERE WEATHER - DESPITE MINIMAL PRE-FRONTAL INSTABILITY INDICATED ALONG AND AHEAD OF THE FRONT. && .MARINE... MAIN STORY FROM A MARINE STANDPOINT IS STABLE CONDITIONS OVER WATER PERSISTING THROUGH THE WEEK. EVEN WITH A FRONTAL PASSAGE ON TUESDAY NIGHT TO EARLY WEDNESDAY TIMEFRAME... NOT ENOUGH COLD ADVECTION EXPECTED TO REALLY MIX HIGHER MOMENTUM TO THE SURFACE. ADDITIONALLY... DON`T EXPECT SURFACE PRESSURE GRADIENT TO REALLY TIGHTEN UP ENOUGH TO OVERCOME STABILITY CONCERNS... AHEAD OF OR BEHIND THR FRONT. BOTTOM LINE... EXPECTING A HARD TIME ACHIEVING EVEN SMALL CRAFT WIND CONDITIONS THIS WEEK ANYWHERE OVER LAKE HURON AND LAKE ST. CLAIR. && .PREV DISCUSSION...ISSUED 100 AM EDT SUN APR 20 2008 / AVIATION... LOWER LEVELS CONTINUE TO REMAIN RATHER DRY. THE 00Z NAM AND RUC SEEM TO HAVE A REASONABLE HANDLE ON THIS LOW LEVEL DRY AIR BASED OFF THE 00Z DTX SOUNDING. BOTH NAM AND RUC SUGGEST CEILINGS WILL REMAIN VFR THROUGH THE DAY...WHICH LOOKS REASONABLE GIVEN UPSTREAM CEILING HEIGHTS ON THE NORTHERN FRINGE OF THE DEEPER MOISTURE ASSOCIATED WITH THE UPPER LOW NOW OVER KENTUCKY. A WEAK AREA OF SURFACE LOW PRESSURE EXTENDING ACROSS SOUTHERN MICHIGAN AND SOUTHERN ONTARIO IS FORECAST TO SLOWLY BUILD TO THE WEST DURING THE COURSE OF THE DAY. DESPITE THE DRY LOWER LEVELS...SOME SHALLOW FOG POTENTIAL STILL LOOKS POSSIBLE DURING THE 08Z AND 14Z TIME FRAME GIVEN THE WEAK SURFACE CONVERGENCE AND UPPER 40 TO LOWER 50 SURFACE DEWPOINTS IN THE AREA. WITH SIGNIFICANT BREAKS IN THE MID CLOUDS AROUND FNT AND MBS...HAVE LOWERED VISIBILITIES TO AROUND 1 MILE BY DAYBREAK. MEANWHILE...WILL RAISE FORECAST VISIBILITIES AROUND DTW SLIGHTLY GIVEN THE MORE EXTENSIVE MID CLOUD DECK. && .DTX WATCHES/WARNINGS/ADVISORIES... MI...NONE. LAKE HURON...NONE. LAKE ST CLAIR...NONE. MI WATERS OF LAKE ERIE...NONE. && $$ SHORT TERM...SF LONG TERM....05 MARINE.......05 AVIATION.....SC 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 130 AM EDT SUN APR 20 2008 UPDATED AVIATION DISCUSSION FOR 06Z TAFS .SYNOPSIS (ISSUED AT 350 PM EDT)... 12Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW DEEPENING UPR TROF ALG THE W COAST AND BLDG RDG OVER THE E HALF OF NAMERICA. CUTOFF LO UNDER THE BLDG RDG IS MOVING E THRU THE OH VALLEY WHILE ANOTHER SHRTWV IS LIFTING INTO WRN LK SUP. INTERACTION OF THIS SHRTWV/ ASSOCIATED UPR DVGC/DPVA/H85-5 QVECTOR CNVGC WITH DEEPER MSTR SHOWN ON THE 12Z MPX RAOB IS CAUSING SCT -SHRA/QUITE A BIT OF LO CLD OVER THE NW HALF OF THE FA EARLY THIS AFTN. BUT 12Z GRB/APX RAOBS SHOW MUCH DRIER AIR IS PRESENT TO THE SE ABV LINGERING SHALLOW MSTR. WITH SE H85 WINDS BTWN CUTOFF LO IN THE OH VALLEY AND HUDSON BAY HI PRES...THIS DRY IS OVERSPRDG THE FA...HAS ENDED THE PCPN OVER THE SCNTRL AND E...AND IS TENDING TO DIMINISH THE SHRA COVG OVER THE NW. && .SHORT TERM (TONIGHT AND SUNDAY ISSUED AT 350 PM EDT)... FOR TNGT...GENERAL MSLP/UPR HGT RISES FCST OVER THE UPR LKS DOWNSTREAM OF DEEPENING TROF IN THE W. WITH PERSISTENT ELY FLOW BTWN HUDSON BAY HI AND DEPARTING CLOSED LO IN THE OH VALLEY...EXPECT DRIER AIR IN THAT DIRECTION TO CONTINUE MAKING INROADS ESE-WNW THRU THE FA. WL RESTRICT MENTION OF POPS THIS EVNG TO THE W BEFORE DROPPING MENTION OF PCPN EXCEPT OVER WRN LK SUP UNDER LINGERING DEEPER MSTR CLOSER TO INCRSGLY SHEARED SHRTWV IMPACTING THAT AREA. EVEN THOUGH THE MID LVLS WL BE DRYING OUT...SUSPECT THE LLVL MSTR WL BE HARDER TO DISLODGE. THIS LLVL MSTR WL BE MOST RESILIENT OVER THE NW IN AREAS WHERE LO CLDS HAVE LINGERED THRU THE DAY AND LIMITED INSOLATION/MIXING. SO WL FCST AREAS OF FOG TO DVLP DESPITE SOME LINGERING HI CLD. HOWEVER...CONDITIONS DON`T APPEAR IDEAL FOR DENSE FOG FORMATION WITH FCST RELATIVELY SHARP PRES GRADIENT BTWN HI TO THE N AND LO IN THE OH VALLEY. EXPECT ONLY PTCHY FOG OVER THE E CONSIDERING THE DEEPER MIXING EVIDENT THERE THIS AFTN. WL TEND TO UNDERCUT MOS FCST LO TEMPS OVER THE INTERIOR E CLOSER TO THE CORE OF THE DRIEST AIR. ON SUN...ACYC ENE FLOW WL DOMINATE THE UPR GRT LKS. WITH DRY AIR ABV THE SFC IN THE MRNG...INSOLATION SHOULD MIX OUT RADIATION FOG. BUT NE FLOW OFF LK SUP MIGHT TEND TO KEEP THE FOG/LO CLD MORE RESILIENT NEAR THE SHORE. DEEP MIXING TO H75 ON GFS FCST SDNGS (NAM/GFS BOTH SHOW H85 TEMPS ARND 10C) WOULD SUPPORT HI TEMPS APRCHG 70 AWAY FM LK MODERATION AS OBSVD IN NRN LWR MI THIS AFTN. BUT TEMPS NEAR LK SUP/ THE GREEN BAY SHOULD BE QUITE A BIT COOLER. SINCE GFS/NAM GENERATE SOME LGT QPF OVER NRN WI BTWN 18Z-24Z...CHECKED FOR THE POTENTIAL FOR SOME INSTABILITY SHRA. BUT EVEN FOR HI TEMPS REACHING AOA 70... UNABLE TO GET ANY SUBSTANTIVE CAPE WITH LLVLS DRIED BY MIXING AND WRMG MID LVLS UNDER UPR RDG. .LONG TERM (SUNDAY NIGHT THROUGH SATURDAY)... THE 500MB RIDGE LOOKS TO REMAIN IN PLACE OVER THE CWA UNTIL SUNDAY NIGHT. AT THAT TIME...SOUTHWESTERLY FLOW WILL BEGIN AS THE TROUGH OVER THE PACIFIC NORTHWEST SLOWLY EDGES EASTWARD TOWARDS THE GREAT LAKES REGION. CAN UNDERSTAND WHY THE TREND HAS CONTINUED...SLOWING THE ONSET OF PRECIPITATION DOWN MONDAY NIGHT AND TUESDAY. IN FACT...IT LOOKS MORE LIKE TUESDAY AFTERNOON BEFORE ANY SIGNIFICANT PRECIPITATION HITS THE WESTERN CWA. HPC GUIDANCE BACKS THIS SCENARIO UP. HOWEVER...THE 12Z RUNS OF THE NAM AND GFS HAVE QUICKENED THINGS UP ROUGHLY 6 HOURS FROM THEIR PREVIOUS RUNS. COMPARED TO THE OTHER OPTIONS...THE GFS WAS QUICKER. CAN NOT IGNORE THIS TREND...AND HAVE MADE SMALL ADJUSTMENTS WHILE ATTEMPTING TO NOT JUMP AROUND TOO MUCH DURING THIS PERIOD. THE PACIFIC TROUGH LOOKS TO SHIFT NE INSTEAD OF STRAIGHT EAST...RESULTING IN A MORE NORTHERLY BROAD SCALE TROUGH FOR US TUESDAY EVENING THROUGH WEDNESDAY AFTERNOON. STILL...CONTINUE TO LOOK FOR THE POTENTIAL FOR HEAVY RAIN AND THUNDERSTORMS AHEAD AND ALONG THE COLD FRONT AS IT SLIDES ACROSS. A HIGH PRESSURE RIDGE IS THEN FIGURED WEDNESDAY NIGHT THROUGH THE DAYTIME HOURS THURSDAY. THEN AGAIN...ANOTHER PACIFIC TROUGH SHOULD EDGE OVER THE WESTERN STATES TO NE MN/SOUTHERN ONTARIO BY 12Z SATURDAY. THE GFS IS THEN MUCH MORE PROGRESSIVE...TRYING TO DIVE THE TROUGH OVER THE SOUTHERN LAKES WHILE OTHER MODELS SEEM TO CONTINUE WITH A GENERAL E TO NE TRACK. FROM FRIDAY ON THE FORECAST BECOMES A BUGABOO. WITH MODEL VARIABILITY PRETTY HIGH...AND FORECAST CONFIDENCE RUNNING LOW AT THIS TIME FRAME...WILL OPT TO UTILIZED HPC GUIDANCE HEAVILY. THIS GENERALLY MEANT FOLLOWING A 00Z ECMWF FORECAST...WITH A BLEND OF ITS ENSEMBLE MEAN. && .HYDROLOGY... LOCATIONS THAT RECEIVED THE LEAST RAINFALL OVER THE LAST 36 HOURS...IN SOUTHERN AND EASTERN UPPER MICHIGAN...WERE ALSO THE LOCATIONS WITH THE SMALLEST SNOWMELT CONCERNS. LOCATIONS TO THE NORTH AND WEST RECEIVED BETWEEN A QUARTER TO A HALF INCH OF RAINFALL...ADDING TO SNOWMELT GOING INTO ALREADY HIGH RIVERS. HIGHS IN THE 40S SATURDAY...AND NEAR 60 ON SUNDAY AND MONDAY WILL RESULT IN RIVER LEVELS CONTINUING TO RISE. EVENING OBS ARE INLINE WITH FORECASTS FROM THE RIVER FORECAST CENTER...SO NO NOTABLE CHANGES HAVE BEEN MADE TO ONGOING STATEMENTS. LOCATIONS WITH THE HIGHEST CONCERN REMAIN THE CHOCOLAY RIVER NEAR HARVEY...AND THE STURGEON RIVER NEAR CHASSELL. FOR CONTINUED UPDATES ON THE RIVERS... PLEASE SEE THE LATEST HYDROLOGIC STATEMENTS AND ANY FLOOD WATCHES OR WARNINGS THAT MAY BE ISSUED. IN ADDITION...FOR THE LATEST FORECAST PLEASE VISIT THE AHPS PAGE AND CLICK ON A RIVER SITE...THIS CAN BE FOUND UNDER THE RIVERS AND LAKES LINK AT WWW.WEATHER.GOV/UP && .AVIATION (FOR THE 06Z TAF ISSUANCE)... FCST REMAINS CHALLENGING AT KSAW AND KCMX. SOMEWHAT DRIER AIR MANAGED TO SLIP INTO KSAW EARLY IN THE EVENING...RESULTING IN CIGS RISING TO VFR. CHECK OF KMQT VAD WIND PROFILE SHOWS LOW-LEVEL WINDS JUST OFF THE SFC HAVE VEERED MORE ERLY THAN EXPECTED...ALLOWING FOR MORE SUBSTANTIAL LOW-LEVEL DRYING. HOWEVER...NOT CONVINCED CIGS WILL REMAIN VFR THRU THE NIGHT. SINCE UPSTREAM SFC DWPTS ARE STILL SIMILAR TO CURRENT TEMP AT KSAW...UPSLOPING WINDS MAY STILL RESULT IN LOW CIGS (LIFR) DEVELOPING. LOOKS LIKE THERE WILL BE SUFFICIENT WIND TO KEEP VIS FROM FALLING ANY LOWER THAN MVFR IF FOG DEVELOPS. EXPECT CONDITIONS TO IMPROVE TO VFR EARLY IN THE AFTN. AT KCMX...A LITTLE MORE CONFIDENT THAT LIFR/IFR CIGS WILL PERSIST THRU THE NIGHT. THERE STILL APPEARS TO BE POTENTIAL FOR VIS TO DROP TO LIFR IN FOG GIVEN LIGHTER WINDS AND RECENT RAINFALL EARLIER IN THE NIGHT. EXPECT CONDITIONS TO IMPROVE TO VFR EARLY IN THE AFTN. && .MARINE (FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)... EXPECT HIGH PRESSURE FROM JAMES BAY INTO QUEBEC TO REMAIN NEARLY STATIONARY THROUGH SUNDAY. MEANWHILE...LOW PRESSURE OVER SOUTHERN LAKE MICHIGAN IS EXPECTED TO DISSIPATE OVER THE SOUTHERN GREAT LAKES BY LATE SUNDAY. ALSO ON SUNDAY...LOW PRESSURE WILL DEVELOP OVER THE NORTHERN ROCKIES...THEN LIFT NORTHEAST TO HUDSON BAY BY TUESDAY EVENING AND DRAG A TROUGH OF LOW PRESSURE ACROSS THE WESTERN GREAT LAKES BY TUESDAY NIGHT. BEHIND THIS TROUGH...HIGH PRESSURE WILL SLIDE SOUTHEAST ACROSS THE GREAT LAKES REGION ON WEDNESDAY. A LOW PRESSURE SYSTEM DEVELOPING OVER THE CENTRAL PLAINS WILL THEN APPROACH THE WESTERN GREAT LAKES REGION ON THURSDAY. FOR THE MOST PART...WINDS SHOULD REMAIN UNDER 20 KTS INTO TUESDAY. EXPECT STRONGER SOUTH WINDS OVER THE EAST IN THE ADVANCE OF THE APPROACHING TROUGH ON TUESDAY/TUESDAY NIGHT. STRONGER WEST TO NORTHWEST WINDS WILL ARRIVE FOLLOWING THE PASSAGE OF THE TROUGH. && .MQT WATCHES/WARNINGS/ADVISORIES...NONE. && $$ SYNOPSIS/SHORT TERM...KC LONG TERM...KF HYDROLOGY...TG/KC/ROLFSON AVIATION...ROLFSON MARINE...KC mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GAYLORD MI 120 AM EDT SUN APR 20 2008 .AVIATION...VFR CONDITIONS THRU THE FORECAST. AN UPPER LEVEL LOW PROGRESSING THRU THE OHIO VALLEY WILL CONTINUE TO SEND MID AND HIGH CLOUDS OUR WAY THRU THE PRE-DAWN HOURS...BUT THESE WILL DIMINISH DURING THE UPCOMING DAY. LIGHT NORTHEAST WINDS WILL PREVAIL...WITH LAKE BREEZES DURING WINDS ONSHORE BY MIDDAY. JZ && .UPDATE...ISSUED 920 PM SAT APR 19... UPPER LOW SPINNING AWAY IN THE OHIO VALLEY...WITH A LESS WELL-DEFINED SURFACE LOW IN THE SOUTHERN LAKES. WE REMAIN TOO FAR NORTH TO HAVE MUCH OF A PRECIP THREAT. EARLIER (ABOUT 530PM)...THE LAKE MI LAKE BREEZE COLLIDED WITH A WELL-DEFINED HORIZONTAL ROLL... SPITTING OUT A SINGLE SHOWER THAT BROUGHT SOME RAINDROPS TO ACME AND MAPLETON. A MORE SUBSTANTIAL AREA OF SHOWERS BLOSSOMED IN W CENTRAL LOWER JUST AFTER THAT...WHERE SURFACE DEW POINTS WERE IN THE 40S (VS THE 30S UP HERE). THESE SHOWERS GRAZED THE MBL AREA. OTHERWISE...MID AND HIGH CLOUDS AND HAZY SKIES ARE THE RULE. GRIDS WERE UPDATED FOR AN ISOLATED SHOWER OR TWO IN THE SW ZONES THRU 02Z/10PM. WITH LOSS OF HEATING...THE REST OF THE NIGHT WILL BE DRY. WILL LOWER MIN TEMPS AT SOME COASTAL LOCATIONS...WHERE LAKE BREEZES HAVE GIVEN THEM A HEAD START IN COOLING OFF. ZOLTOWSKI && .PREV DISCUSSION...ISSUED 303 PM SAT APR 19... LATEST RUC ANALYSIS AND VIS/IR/WV/RADAR IMAGERY SHOW AN UPPER LEVEL LOW SPINNING OVER THE SOUTHERN IL-IN BORDER AND A BROAD AREA OF SURFACE LOW PRESSURE OVER THE SOUTHERN GREAT LAKES. BANDS OF MID AND UPPER LEVEL CLOUD COVER CONTINUE TO ROTATE ACROSS NORTHERN MICHIGAN WITH HOLES IN THE CIRRUS SHIELD APPEARING EVERY NOW AND THEN. THESE CLOUDS HAVE NOT PREVENTED TEMPERATURES FROM RAPIDLY WARMING INTO THE LOW TO MID 70S INLAND. WITH PRECIP WELL TO THE SOUTH OVER FAR SOUTHERN LOWER MICHIGAN...MAIN FORECAST CONCERNS INCLUDE TEMPS AND SKY COVER TONIGHT...THEN SMALL CHANCES OF PRECIP ALONG LAKE BREEZE BOUNDARIES TOMORROW. TONIGHT...UPPER LOW WILL DRIFT SLIGHTLY SOUTH OF EAST AS IT CUTS ACROSS THE OHIO RIVER VALLEY TO THE CENTRAL APPALACHIANS. SPOKE OF UPPER LEVEL MOISTURE WILL PINWHEEL ACROSS NORTHERN MICHIGAN TONIGHT...BUT FORCING AND DEEP MOISTURE WILL REMAIN WELL SOUTH OF THE REGION. THAT LEAVES TEMPERATURES AND SKY COVER TO THINK ABOUT. LOWS LAST NIGHT DIPPED INTO THE MIDDLE AND UPPER 30S ACROSS NE LOWER WHERE CLEAR SKIES HUNG ON THE LONGEST. DO NOT THINK THAT WILL HAPPEN TONIGHT DUE TO THE CIRRUS SHIELD...EVEN THOUGH THIS CIRRUS WILL THIN OVERNIGHT ACROSS NORTHERN LOWER. SO HAVE KEPT LOWS SIMILAR TO LAST NIGHT EXCEPT RAISED THEM A FEW DEGREES OVER NE LOWER. LOWS IN THE 40S. TOMORROW...UPPER LOW WILL MEANDER ACROSS THE CENTRAL APPALACHIANS WHILE MID-LEVEL HEIGHTS SLOWLY BUILD ACROSS THE NORTHERN GREAT LAKES. NO LARGE-SCALE FORCING TO SPEAK UP WITH THE BUILDING RIDGE...BUT STILL HINTS THAT LOCALIZED CONVERGENCE WILL SETUP ACROSS THE SW CWA WITH PREVAILING EAST FLOW BUTTING HEADS AGAINST LAKE BREEZES OFF OF LAKE MICHIGAN AND GRAND TRAVERSE BAY. BOTH NAM/GFS SPIT OUT QPF CENTERED AROUND WEXFORD COUNTY...BUT THINK THIS IS MORE OF A BY-PRODUCT OF OVER-GENEROUS SURFACE DEWPOINTS...WHICH BOTH MODELS SHOW IN THE LOWER TO MID 50S. DEEP MIXING UP TO 775MB SUGGESTS DEWPOINTS WILL MIX OUT TO AROUND 48F. USING A TEMP OF 72F...THIS WOULD YIELD SKINNY ML CAPES AROUND 200 J/KG IN THE MORE MOIST NAM SOLUTION...WHILE THE DRIER GFS SUGGESTS TOO MUCH CIN WILL EXIST TO TRIGGER A SHOWER. GIVEN THE INCREASING SUBSIDENCE THROUGH THE DAY...LEAN MORE TOWARD THE DRIER SOLUTION AND WILL LEAVE POPS OUT OF THE FORECAST. ANOTHER WARM DAY ON TAP WITH HIGHS RANGING FROM THE MID 60S NORTH/NEAR LAKESHORES...TO THE LOWER 70S INLAND. MPC SUN NIGHT THRU MON NIGHT...RATHER QUIET PERIOD OF WX EXPECTED TO CONTINUE...THOUGH A FEW FCST CONCERNS REMAIN...NAMELY TEMPS MON AFTN ALONG WITH ANY SMALL PRECIP CHANCES THRU THE PERIOD. POTENT CLOSED LOW SPINNING OVR SOUTHERN IN THIS AFTN PROGGED TO SLIP INTO VIRGINIA BY EARLY MON...WITH BROAD SHORTWAVE RIDGING BUILDING ACRS THE LAKES IN ADVANCE OF NEXT UPSTREAM TROUGH OVR THE NORTHWEST. HOWEVER... CONCERN REGARDING POTENTIAL PRECIP STEMS FROM BROAD PLUME OF WRAP AROUND MOISTURE PROGGED TO ADVECT BACK INTO THE REGION SUN NIGHT TIMEFRAME...AS UPR GYRE ABLE TO TAP ADDITIONAL MOISTURE FROM THE ATLANTIC. INTERESTING TO NOTE BOTH NAM AND GFS SPIT OUT A HINT OF MEASURABLE PRECIP SUN NIGHT/EARLY MON THOUGH DIFFICULT TO FORESEE THIS GIVEN OVERALL LACK OF MID/UPR LEVEL MOISTURE AND FORCING...WITH ONLY SOME WEAK HINT OF CHANNELED VORT (REMNANTS OF CLOSED LOW TO THE SOUTH TODAY) HEADING NORTH THRU THE NIGHT. THUS WILL MAINTAIN DRY FCST AT THIS TIME. HEADING INTO MON AFTN...APPEARS ANOTHER WARM DAY ON TAP WITH DEVELOPING SOUTHERLY FLOW AHEAD OF APPROACHING UPR TROUGH...THOUGH OVERALL LACK OF MIXING PER LOW LEVEL RIDGE AXIS DRAPED OVERHEAD SHOULD KNOCK A FEW DEGREE OFF POTENTIAL HIGHS (READINGS MAINLY MID/UPR 60S LOOK GOOD). DESPITE GOOD HEATING AND LIKELY LAKE BREEZE CONVERGENCE ALONG THE LAKE MICHIGAN SIDE... DIFFICULT TO SEE CONVECTION (OTHER THAN A FAIRLY HEALTHY CU FIELD) FIRING DESPITE AN INCREASE IN BOUNDARY LAYER MOISTURE...AS MID LEVEL SUBSIDENCE INVERSION BUILDS THRU THE DAY. LATER PERIODS (TUE THRU SAT)...PATTERN TO REMAIN QUITE BLOCKY THRU THE EXTENDED PORTION OF THE FCST...OWING TO HIGHLY AMPLIFIED/ CLOSED MID LEVEL RIDGE ACRS CENTRAL/EASTERN ALASKA...IMPLYING SIGNIFICANT DOWNSTREAM TROUGHING INTO THE WESTERN CONUS. INDEED... THIS TYPE OF PATTERN IS WHAT THE MEDIUM RANGE GUIDANCE CONTINUES TO SUGGEST...WITH INITIAL CLOSED LOW (EVIDENT THIS AFTN NEAR THE BRITISH COLUMBIA/WASHINGTON STATE BORDER) AND ASSOCIATED ENERGY SHEARING OUT INTO THE NORTHERN PLAINS/UPR MIDWEST ON TUE...OWING TO BRIEF DISRUPTION OF BLOCKING FLOW ACRS THE EASTERN PACIFIC AS ENERGY UNDERCUTS THE RIDGE. END RESULT FOR NORTHERN MI WILL BE INCREASING CHANCES FOR PRECIP TUE NIGHT AS ASSOCIATED SFC FRONT AND WEAKENING FORCING SLIDES THRU THE REGION. WILL CONTINUE THUNDER MENTION AS WELL WITH EXPECTED DECENT MOISTURE TAP INTO THE AREA VIA OPEN GULF...AND MODEL PROGS OF SHOWALTER INDICES DIPPING WELL BELOW 0C ALONG WITH STEEPER MID LEVEL LAPSE RATE PLUME OVERHEAD. PONDERED BRINGING SMALL POPS BACK INTO THE PICTURE FOR TUE AFTN AS MOISTURE INCREASES AHEAD OF THE FRONT...WITH POTENTIAL FOR BRIEF CONVECTION TO POP AHEAD OF THE BOUNDARY GIVEN EXPECTED HEATING AND LIKELY LOW LEVEL WEAK UPSLOPE REGIME INTO THE HIGHER TERRAIN PER BACKING OF FLOW AHEAD OF THE FRONT...THOUGH ANYTHING ISOLATED AT BEST SO DRY FCST WILL CONTINUE. TEMPS TUE IFFY PENDING DEGREE OF SUN...THOUGH POTENTIAL IS THERE FOR A VERY WARM DAY WITH REGION IN THE THERMAL RIDGE AHEAD OF THE FRONT. WILL RUN WITH MID 60S TO LOWER 70S AREAWIDE. STILL LOOKS LIKE A DRY AND MORE SEASONABLE DAY ON TAP FOR THU AS LOW/MID LEVEL RIDGING AND ASSOCIATED SUBSIDENCE/DRYING TAKE HOLD. 00Z GUIDANCE NUMBERS APPEAR A BIT TOO COOL GIVEN EXPECTED SUN...SO WILL RUN WITH TEMPS UPR 50S TO MID 60S. THEREAFTER...GUIDANCE BEGINS TO DIVERGE ON AMPLITUDE OF ADDITIONAL WESTERN TROUGHING THU/FRI...THOUGH PATTERN RECOGNITION WITH DEEP LAYER/MERIDIONAL RIDGE BECOMING RE-ESTABLISHED ACRS ALASKA CERTAINLY ARGUES FOR THE ECMWF/GEFS MEAN SOLUTIONS OF A DEEPER WESTERN TROUGH. REGARDLESS OF EVENTUAL SOLUTION...IMPLICATION FOR THE CWA IS ADDITIONAL PRECIP CHANCES FRI/SAT TIMEFRAME AS LEE CYCLOGENESIS GETS GOING ON THE PLAINS...WITH ASSOCIATED COLD FRONT HEADING EAST BY THE WEEKEND. LAWRENCE && .APX WATCHES/WARNINGS/ADVISORIES... MI...NONE. LM...NONE. LH...NONE. LS...NONE. && $$ mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE DETROIT/PONTIAC MI 100 AM EDT SUN APR 20 2008 .AVIATION... LOWER LEVELS CONTINUE TO REMAIN RATHER DRY. THE 00Z NAM AND RUC SEEM TO HAVE A REASONABLE HANDLE ON THIS LOW LEVEL DRY AIR BASED OFF THE 00Z DTX SOUNDING. BOTH NAM AND RUC SUGGEST CEILINGS WILL REMAIN VFR THROUGH THE DAY...WHICH LOOKS REASONABLE GIVEN UPSTREAM CEILING HEIGHTS ON THE NORTHERN FRINGE OF THE DEEPER MOISTURE ASSOCIATED WITH THE UPPER LOW NOW OVER KENTUCKY. A WEAK AREA OF SURFACE LOW PRESSURE EXTENDING ACROSS SOUTHERN MICHIGAN AND SOUTHERN ONTARIO IS FORECAST TO SLOWLY BUILD TO THE WEST DURING THE COURSE OF THE DAY. DESPITE THE DRY LOWER LEVELS...SOME SHALLOW FOG POTENTIAL STILL LOOKS POSSIBLE DURING THE 08Z AND 14Z TIME FRAME GIVEN THE WEAK SURFACE CONVERGENCE AND UPPER 40 TO LOWER 50 SURFACE DEWPOINTS IN THE AREA. WITH SIGNIFICANT BREAKS IN THE MID CLOUDS AROUND FNT AND MBS...HAVE LOWERED VISIBILITIES TO AROUND 1 MILE BY DAYBREAK. MEANWHILE...WILL RAISE FORECAST VISIBILITIES AROUND DTW SLIGHTLY GIVEN THE MORE EXTENSIVE MID CLOUD DECK. && .PREV DISCUSSION...ISSUED 1000 PM EDT SAT APR 19 2008 UPDATE... UPSTREAM RADAR IMAGERY SUGGESTS BULK OF RAIN SHOWERS WILL REMAIN JUST SOUTH OF THE STATE LINE...WITH SCATTERED ACTIVITY IMPACTING ROUGHLY THE M 59 CORRIDOR SOUTHWARD. WILL UPDATE THE GRIDS/ZONES TO ACCOUNT FOR THESE LATEST TRENDS AND TO LOWER POPS ALONG AND NORTH OF THE I 69 CORRIDOR. THE BETTER CHANCES FOR PRECIP FARTHER NORTH SHOULD HOLD OFF UNTIL LATE TONIGHT WHEN SOME MID LEVEL DEFORMATION ASSOCIATED WITH THE OHIO VALLEY UPPER LOW BEGINS TO MOVE IN FROM THE EAST. DEWPOINTS HOLDING IN THE MID 40S TO LOWER 50S ALONG WITH A LINGERING SURFACE TROUGH OVER SOUTHERN MICHIGAN WILL CONTINUE TO SUPPORT AREAS OF FOG LATE TONIGHT. SOME CLEAR SKIES TO THE NORTH WILL ALSO HELP IN RADIATIONAL COOLING. THE ONLY OTHER UPDATE TO THE FORECAST WILL BE TO LOWER TEMPS A COUPLE DEGREES AROUND THE TRI CITIES WHERE TEMPS ARE ALREADY IN THE LOWER 50S THANKS TO THE MARINE LAYER THAT HAD ADVECTED INLAND OFF SAGINAW BAY. PREV DISCUSSION...ISSUED 330 PM EDT SAT APR 19 2008 SHORT TERM...TONIGHT THE BEST CHANCE OF RAIN TONIGHT WILL BE NEAR THE OHIO BORDER BUT CLOUDS AND MILD TEMPERATURES WILL AFFECT ALL OF SE MICHIGAN TONIGHT. RADAR COMPOSITES INDICATE PRECIPITATION HAS TAKEN ON MORE IMPRESSIVE AREAL COVERAGE OVER SOUTHERN/WESTERN OHIO THIS AFTERNOON. THIS IS WHERE A RESPECTABLE COMBINATION OF FORCING IS COMING TOGETHER ON THE EAST FLANK OF THE UPPER LOW. SATELLITE AND MODEL FIELDS INDICATE THE UPPER LOW IS DOING A GOOD JOB OF BENDING THE LOW TO MID LEVEL THETA-E RIDGE AND APPLYING SOME MODEST DYNAMIC FORCING TO THE MOISTURE TRANSPORT. THIS IS COMBINED WITH SOME COOLER TEMPERATURES ALOFT AND SOME POCKETS OF DAYTIME HEATING GENERATING ENOUGH INSTABILITY FOR ADDED SHOWER COVERAGE ALONG WITH A FEW THUNDERSTORMS. NOW THAT IT IS UNDERWAY, THE PERSISTENCE OF INSTABILITY INTO THIS EVENING WILL KEEP THE SHOWERS/STORMS GOING AS THEY ROTATE TOWARD THE OHIO BORDER REGION OF SE MICHIGAN. THIS WILL OCCUR AS THE ENTIRE LOW PRESSURE SYSTEM SLIDES EASTWARD AND SOUTH OF THE OHIO RIVER. THE SLIGHTLY SE TRACK OF THE SYSTEM WILL KEEP RAIN FROM MOVING VERY FAR NORTHWARD INTO OUR AREA BUT IS STILL WORTHY OF NUMEROUS COVERAGE FOR LENAWEE AND MONROE COUNTIES. LATER ON TONIGHT, EXPECT JUST A GENERAL CHANCE OF LIGHT RAIN SHOWERS IN THE NW PORTION OF THE SYSTEM. THIS WOULD BE DUE TO WEAK MID LEVEL DEFORMATION OVER THE TOP OF THE FILLING SURFACE TROUGH/LOW. MORE IMPORTANT MIGHT BE THE PATCHY FOG EXPECTED TO DEVELOP TOWARD SUNRISE. AS THE SURFACE TROUGH SETTLES INTO LOWER MICHIGAN AND GRADUALLY FILLS/DRIFTS NORTHWEST IT WILL PULL HIGHER DEWPOINT AIR INTO THE REGION WITH SOME POCKETS OF 1 MILE FOG POSSIBLE LATE IN THE NIGHT THROUGH A COUPLE HOURS AFTER SUNRISE SUNDAY MORNING. LONG TERM...SUNDAY THROUGH SATURDAY RESIDUAL TROUGHING WILL PERSIST ON SUNDAY AS THE UPPER LOW DRIFTING ACROSS THE OHIO VALLEY WEAKENS AND TRACKS EAST/SOUTHEAST. WITH MINOR INSTABILITY FROM DAYTIME HEATING...THE CHANCE OF SHOWERS STILL SEEMS REASONABLE AND WILL MAINTAIN THE CURRENT WORDING IN THE FORECAST. DRY WEATHER IS THEN EXPECTED FROM SUNDAY NIGHT INTO TUESDAY AS THIS FEATURE CONTINUE TO DRIFT TO THE EAST COAST...AND UPPER RIDGING AND SURFACE HIGH PRESSURE REMAIN IN PLACE FROM THE GREAT LAKES EAST INTO NEW ENGLAND. DURING THIS TIMEFRAME...A BROAD WESTERN TROUGH WILL BE TAKING SHAPE OVER WESTERN/CENTRAL CANADA INTO THE CONUS. THIS WILL ESTABLISH A MUCH MORE PROGRESSIVE PATTERN OVER THE AREA BY THE MIDDLE OF NEXT WEEK ON INTO NEXT WEEKEND. TIMING INDIVIDUAL DISTURBANCE INTO AND THROUGH THE AREA WILL CONTINUE TO BE AN ISSUE...BUT CONSISTENCY IS SOMEWHAT REASONABLE FOR THE FIRST COLD FRONT...WHICH MOVES THROUGH THE AREA ON TUESDAY NIGHT INTO WEDNESDAY MORNING...AND THE FORECAST IS IN GOOD SHAPE WITH THIS SCENARIO. BY LATE IN THE WEEK...A MORE SUBSTANTIAL STORM SYSTEM APPEARS TO BE DEVELOPING AS A SHORTWAVE IS FORECAST TO DIG SOUTHEAST INTO THE CENTRAL PLAINS WITH A LITTLE MORE AUTHORITY. SUCH A FEATURE SHOULD BE ABLE TAP ADDITIONAL MOISTURE FROM THE SOUTHERN CONUS AND GULF OF MEXICO...LEADING TO SEVERAL DAY PERIOD WITH SHOWERS/THUNDERSTORMS. FIRST...WITH THIS WARM/MOIST SURGE IN ADVANCE OF THE STORM...AND THEN WITH THE STORM CENTER ITSELF. PRECIPITATION WILL BE CARRIED FROM THURSDAY NIGHT INTO THE WEEKEND. TEMPERATURES WILL REMAIN MILD WITH HIGHS IN THE 60S TO AROUND 70 AND LOWS IN THE 40S TO AROUND 50...WHICH IS SLIGHTLY ABOVE NORMAL FOR THIS PART OF APRIL. MARINE... A BROAD AREA OF LOW PRESSURE LOCATED OVER THE SOUTHERN GREAT LAKES TODAY WILL GRADUALLY FILL LATE TONIGHT AND SUNDAY. THIS PROCESS WILL CONFINE THE BEST CHANCE OF RAIN TO LAKE ST CLAIR AND LAKE ERIE TONIGHT, BUT WILL KEEP FAVORABLE WIND AND WAVE CONDITIONS OVER THE ENTIRE REGION THROUGH THE REST OF THE WEEKEND. MODEST SE WINDS WILL THEN PERSIST THROUGH MONDAY AS THE NEXT LOW PRESSURE SYSTEM DEVELOPS IN THE PLAINS. THIS SYSTEM WILL TRACK FROM THE PLAINS ON MONDAY TO THE NORTH OF LAKE SUPERIOR ON TUESDAY AND WILL DRAG A COLD FRONT THROUGH THE REGION DURING THE MID WEEK PERIOD. 30 KNOT WIND SPEEDS WILL BE POSSIBLE OVER THE OPEN WATERS OF LAKE HURON TUESDAY NIGHT. && .DTX WATCHES/WARNINGS/ADVISORIES... MI...NONE. LAKE HURON...NONE. LAKE ST CLAIR...NONE. MI WATERS OF LAKE ERIE...NONE. && $$ AVIATION.....SC UPDATE.......SC SHORT TERM...BT LONG TERM....DG MARINE.......BT 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 GAYLORD MI 920 PM EDT SAT APR 19 2008 .UPDATE...UPPER LOW SPINNING AWAY IN THE OHIO VALLEY...WITH A LESS WELL-DEFINED SURFACE LOW IN THE SOUTHERN LAKES. WE REMAIN TOO FAR NORTH TO HAVE MUCH OF A PRECIP THREAT. EARLIER (ABOUT 530PM)...THE LAKE MI LAKE BREEZE COLLIDED WITH A WELL-DEFINED HORIZONTAL ROLL... SPITTING OUT A SINGLE SHOWER THAT BROUGHT SOME RAINDROPS TO ACME AND MAPLETON. A MORE SUBSTANTIAL AREA OF SHOWERS BLOSSOMED IN W CENTRAL LOWER JUST AFTER THAT...WHERE SURFACE DEW POINTS WERE IN THE 40S (VS THE 30S UP HERE). THESE SHOWERS GRAZED THE MBL AREA. OTHERWISE...MID AND HIGH CLOUDS AND HAZY SKIES ARE THE RULE. GRIDS WERE UPDATED FOR AN ISOLATED SHOWER OR TWO IN THE SW ZONES THRU 02Z/10PM. WITH LOSS OF HEATING...THE REST OF THE NIGHT WILL BE DRY. WILL LOWER MIN TEMPS AT SOME COASTAL LOCATIONS...WHERE LAKE BREEZES HAVE GIVEN THEM A HEAD START IN COOLING OFF. ZOLTOWSKI && .AVIATION...ISSUED 710 PM SAT APR 19... LOW PRESSURE WILL STEADILY MOVE EAST ACROSS THE OHIO VALLEY. FAIR AMOUNT OF MID/HIGH CLOUDS AND HAZE ALOFT...BUT SHOWERS WILL STAY SOUTH OF ALL TAF SITES. WEATHER WILL REMAIN WARM...WITH LAKE BREEZES DEVELOPING AGAIN SUNDAY AFTERNOON AGAINST A BACKDROP OF OTHERWISE LIGHT EASTERLY WINDS. VFR THRU THE FORECAST. JZ && .PREV DISCUSSION...ISSUED 303 PM SAT APR 19... LATEST RUC ANALYSIS AND VIS/IR/WV/RADAR IMAGERY SHOW AN UPPER LEVEL LOW SPINNING OVER THE SOUTHERN IL-IN BORDER AND A BROAD AREA OF SURFACE LOW PRESSURE OVER THE SOUTHERN GREAT LAKES. BANDS OF MID AND UPPER LEVEL CLOUD COVER CONTINUE TO ROTATE ACROSS NORTHERN MICHIGAN WITH HOLES IN THE CIRRUS SHIELD APPEARING EVERY NOW AND THEN. THESE CLOUDS HAVE NOT PREVENTED TEMPERATURES FROM RAPIDLY WARMING INTO THE LOW TO MID 70S INLAND. WITH PRECIP WELL TO THE SOUTH OVER FAR SOUTHERN LOWER MICHIGAN...MAIN FORECAST CONCERNS INCLUDE TEMPS AND SKY COVER TONIGHT...THEN SMALL CHANCES OF PRECIP ALONG LAKE BREEZE BOUNDARIES TOMORROW. TONIGHT...UPPER LOW WILL DRIFT SLIGHTLY SOUTH OF EAST AS IT CUTS ACROSS THE OHIO RIVER VALLEY TO THE CENTRAL APPALACHIANS. SPOKE OF UPPER LEVEL MOISTURE WILL PINWHEEL ACROSS NORTHERN MICHIGAN TONIGHT...BUT FORCING AND DEEP MOISTURE WILL REMAIN WELL SOUTH OF THE REGION. THAT LEAVES TEMPERATURES AND SKY COVER TO THINK ABOUT. LOWS LAST NIGHT DIPPED INTO THE MIDDLE AND UPPER 30S ACROSS NE LOWER WHERE CLEAR SKIES HUNG ON THE LONGEST. DO NOT THINK THAT WILL HAPPEN TONIGHT DUE TO THE CIRRUS SHIELD...EVEN THOUGH THIS CIRRUS WILL THIN OVERNIGHT ACROSS NORTHERN LOWER. SO HAVE KEPT LOWS SIMILAR TO LAST NIGHT EXCEPT RAISED THEM A FEW DEGREES OVER NE LOWER. LOWS IN THE 40S. TOMORROW...UPPER LOW WILL MEANDER ACROSS THE CENTRAL APPALACHIANS WHILE MID-LEVEL HEIGHTS SLOWLY BUILD ACROSS THE NORTHERN GREAT LAKES. NO LARGE-SCALE FORCING TO SPEAK UP WITH THE BUILDING RIDGE...BUT STILL HINTS THAT LOCALIZED CONVERGENCE WILL SETUP ACROSS THE SW CWA WITH PREVAILING EAST FLOW BUTTING HEADS AGAINST LAKE BREEZES OFF OF LAKE MICHIGAN AND GRAND TRAVERSE BAY. BOTH NAM/GFS SPIT OUT QPF CENTERED AROUND WEXFORD COUNTY...BUT THINK THIS IS MORE OF A BY-PRODUCT OF OVER-GENEROUS SURFACE DEWPOINTS...WHICH BOTH MODELS SHOW IN THE LOWER TO MID 50S. DEEP MIXING UP TO 775MB SUGGESTS DEWPOINTS WILL MIX OUT TO AROUND 48F. USING A TEMP OF 72F...THIS WOULD YIELD SKINNY ML CAPES AROUND 200 J/KG IN THE MORE MOIST NAM SOLUTION...WHILE THE DRIER GFS SUGGESTS TOO MUCH CIN WILL EXIST TO TRIGGER A SHOWER. GIVEN THE INCREASING SUBSIDENCE THROUGH THE DAY...LEAN MORE TOWARD THE DRIER SOLUTION AND WILL LEAVE POPS OUT OF THE FORECAST. ANOTHER WARM DAY ON TAP WITH HIGHS RANGING FROM THE MID 60S NORTH/NEAR LAKESHORES...TO THE LOWER 70S INLAND. MPC SUN NIGHT THRU MON NIGHT...RATHER QUIET PERIOD OF WX EXPECTED TO CONTINUE...THOUGH A FEW FCST CONCERNS REMAIN...NAMELY TEMPS MON AFTN ALONG WITH ANY SMALL PRECIP CHANCES THRU THE PERIOD. POTENT CLOSED LOW SPINNING OVR SOUTHERN IN THIS AFTN PROGGED TO SLIP INTO VIRGINIA BY EARLY MON...WITH BROAD SHORTWAVE RIDGING BUILDING ACRS THE LAKES IN ADVANCE OF NEXT UPSTREAM TROUGH OVR THE NORTHWEST. HOWEVER... CONCERN REGARDING POTENTIAL PRECIP STEMS FROM BROAD PLUME OF WRAP AROUND MOISTURE PROGGED TO ADVECT BACK INTO THE REGION SUN NIGHT TIMEFRAME...AS UPR GYRE ABLE TO TAP ADDITIONAL MOISTURE FROM THE ATLANTIC. INTERESTING TO NOTE BOTH NAM AND GFS SPIT OUT A HINT OF MEASURABLE PRECIP SUN NIGHT/EARLY MON THOUGH DIFFICULT TO FORESEE THIS GIVEN OVERALL LACK OF MID/UPR LEVEL MOISTURE AND FORCING...WITH ONLY SOME WEAK HINT OF CHANNELED VORT (REMNANTS OF CLOSED LOW TO THE SOUTH TODAY) HEADING NORTH THRU THE NIGHT. THUS WILL MAINTAIN DRY FCST AT THIS TIME. HEADING INTO MON AFTN...APPEARS ANOTHER WARM DAY ON TAP WITH DEVELOPING SOUTHERLY FLOW AHEAD OF APPROACHING UPR TROUGH...THOUGH OVERALL LACK OF MIXING PER LOW LEVEL RIDGE AXIS DRAPED OVERHEAD SHOULD KNOCK A FEW DEGREE OFF POTENTIAL HIGHS (READINGS MAINLY MID/UPR 60S LOOK GOOD). DESPITE GOOD HEATING AND LIKELY LAKE BREEZE CONVERGENCE ALONG THE LAKE MICHIGAN SIDE... DIFFICULT TO SEE CONVECTION (OTHER THAN A FAIRLY HEALTHY CU FIELD) FIRING DESPITE AN INCREASE IN BOUNDARY LAYER MOISTURE...AS MID LEVEL SUBSIDENCE INVERSION BUILDS THRU THE DAY. LATER PERIODS (TUE THRU SAT)...PATTERN TO REMAIN QUITE BLOCKY THRU THE EXTENDED PORTION OF THE FCST...OWING TO HIGHLY AMPLIFIED/ CLOSED MID LEVEL RIDGE ACRS CENTRAL/EASTERN ALASKA...IMPLYING SIGNIFICANT DOWNSTREAM TROUGHING INTO THE WESTERN CONUS. INDEED... THIS TYPE OF PATTERN IS WHAT THE MEDIUM RANGE GUIDANCE CONTINUES TO SUGGEST...WITH INITIAL CLOSED LOW (EVIDENT THIS AFTN NEAR THE BRITISH COLUMBIA/WASHINGTON STATE BORDER) AND ASSOCIATED ENERGY SHEARING OUT INTO THE NORTHERN PLAINS/UPR MIDWEST ON TUE...OWING TO BRIEF DISRUPTION OF BLOCKING FLOW ACRS THE EASTERN PACIFIC AS ENERGY UNDERCUTS THE RIDGE. END RESULT FOR NORTHERN MI WILL BE INCREASING CHANCES FOR PRECIP TUE NIGHT AS ASSOCIATED SFC FRONT AND WEAKENING FORCING SLIDES THRU THE REGION. WILL CONTINUE THUNDER MENTION AS WELL WITH EXPECTED DECENT MOISTURE TAP INTO THE AREA VIA OPEN GULF...AND MODEL PROGS OF SHOWALTER INDICES DIPPING WELL BELOW 0C ALONG WITH STEEPER MID LEVEL LAPSE RATE PLUME OVERHEAD. PONDERED BRINGING SMALL POPS BACK INTO THE PICTURE FOR TUE AFTN AS MOISTURE INCREASES AHEAD OF THE FRONT...WITH POTENTIAL FOR BRIEF CONVECTION TO POP AHEAD OF THE BOUNDARY GIVEN EXPECTED HEATING AND LIKELY LOW LEVEL WEAK UPSLOPE REGIME INTO THE HIGHER TERRAIN PER BACKING OF FLOW AHEAD OF THE FRONT...THOUGH ANYTHING ISOLATED AT BEST SO DRY FCST WILL CONTINUE. TEMPS TUE IFFY PENDING DEGREE OF SUN...THOUGH POTENTIAL IS THERE FOR A VERY WARM DAY WITH REGION IN THE THERMAL RIDGE AHEAD OF THE FRONT. WILL RUN WITH MID 60S TO LOWER 70S AREAWIDE. STILL LOOKS LIKE A DRY AND MORE SEASONABLE DAY ON TAP FOR THU AS LOW/MID LEVEL RIDGING AND ASSOCIATED SUBSIDENCE/DRYING TAKE HOLD. 00Z GUIDANCE NUMBERS APPEAR A BIT TOO COOL GIVEN EXPECTED SUN...SO WILL RUN WITH TEMPS UPR 50S TO MID 60S. THEREAFTER...GUIDANCE BEGINS TO DIVERGE ON AMPLITUDE OF ADDITIONAL WESTERN TROUGHING THU/FRI...THOUGH PATTERN RECOGNITION WITH DEEP LAYER/MERIDIONAL RIDGE BECOMING RE-ESTABLISHED ACRS ALASKA CERTAINLY ARGUES FOR THE ECMWF/GEFS MEAN SOLUTIONS OF A DEEPER WESTERN TROUGH. REGARDLESS OF EVENTUAL SOLUTION...IMPLICATION FOR THE CWA IS ADDITIONAL PRECIP CHANCES FRI/SAT TIMEFRAME AS LEE CYCLOGENESIS GETS GOING ON THE PLAINS...WITH ASSOCIATED COLD FRONT HEADING EAST BY THE WEEKEND. LAWRENCE && .APX WATCHES/WARNINGS/ADVISORIES... MI...NONE. LM...NONE. LH...NONE. LS...NONE. && $$ mi AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE MARQUETTE MI 738 PM EDT SAT APR 19 2008 UPDATED AVIATION DISCUSSION FOR 00Z TAFS .SYNOPSIS (ISSUED AT 350 PM EDT)... 12Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW DEEPENING UPR TROF ALG THE W COAST AND BLDG RDG OVER THE E HALF OF NAMERICA. CUTOFF LO UNDER THE BLDG RDG IS MOVING E THRU THE OH VALLEY WHILE ANOTHER SHRTWV IS LIFTING INTO WRN LK SUP. INTERACTION OF THIS SHRTWV/ ASSOCIATED UPR DVGC/DPVA/H85-5 QVECTOR CNVGC WITH DEEPER MSTR SHOWN ON THE 12Z MPX RAOB IS CAUSING SCT -SHRA/QUITE A BIT OF LO CLD OVER THE NW HALF OF THE FA EARLY THIS AFTN. BUT 12Z GRB/APX RAOBS SHOW MUCH DRIER AIR IS PRESENT TO THE SE ABV LINGERING SHALLOW MSTR. WITH SE H85 WINDS BTWN CUTOFF LO IN THE OH VALLEY AND HUDSON BAY HI PRES...THIS DRY IS OVERSPRDG THE FA...HAS ENDED THE PCPN OVER THE SCNTRL AND E...AND IS TENDING TO DIMINISH THE SHRA COVG OVER THE NW. .SHORT TERM (TONIGHT AND SUNDAY ISSUED AT 350 PM EDT)... FOR TNGT...GENERAL MSLP/UPR HGT RISES FCST OVER THE UPR LKS DOWNSTREAM OF DEEPENING TROF IN THE W. WITH PERSISTENT ELY FLOW BTWN HUDSON BAY HI AND DEPARTING CLOSED LO IN THE OH VALLEY...EXPECT DRIER AIR IN THAT DIRECTION TO CONTINUE MAKING INROADS ESE-WNW THRU THE FA. WL RESTRICT MENTION OF POPS THIS EVNG TO THE W BEFORE DROPPING MENTION OF PCPN EXCEPT OVER WRN LK SUP UNDER LINGERING DEEPER MSTR CLOSER TO INCRSGLY SHEARED SHRTWV IMPACTING THAT AREA. EVEN THOUGH THE MID LVLS WL BE DRYING OUT...SUSPECT THE LLVL MSTR WL BE HARDER TO DISLODGE. THIS LLVL MSTR WL BE MOST RESILIENT OVER THE NW IN AREAS WHERE LO CLDS HAVE LINGERED THRU THE DAY AND LIMITED INSOLATION/MIXING. SO WL FCST AREAS OF FOG TO DVLP DESPITE SOME LINGERING HI CLD. HOWEVER...CONDITIONS DON`T APPEAR IDEAL FOR DENSE FOG FORMATION WITH FCST RELATIVELY SHARP PRES GRADIENT BTWN HI TO THE N AND LO IN THE OH VALLEY. EXPECT ONLY PTCHY FOG OVER THE E CONSIDERING THE DEEPER MIXING EVIDENT THERE THIS AFTN. WL TEND TO UNDERCUT MOS FCST LO TEMPS OVER THE INTERIOR E CLOSER TO THE CORE OF THE DRIEST AIR. ON SUN...ACYC ENE FLOW WL DOMINATE THE UPR GRT LKS. WITH DRY AIR ABV THE SFC IN THE MRNG...INSOLATION SHOULD MIX OUT RADIATION FOG. BUT NE FLOW OFF LK SUP MIGHT TEND TO KEEP THE FOG/LO CLD MORE RESILIENT NEAR THE SHORE. DEEP MIXING TO H75 ON GFS FCST SDNGS (NAM/GFS BOTH SHOW H85 TEMPS ARND 10C) WOULD SUPPORT HI TEMPS APRCHG 70 AWAY FM LK MODERATION AS OBSVD IN NRN LWR MI THIS AFTN. BUT TEMPS NEAR LK SUP/ THE GREEN BAY SHOULD BE QUITE A BIT COOLER. SINCE GFS/NAM GENERATE SOME LGT QPF OVER NRN WI BTWN 18Z-24Z...CHECKED FOR THE POTENTIAL FOR SOME INSTABILITY SHRA. BUT EVEN FOR HI TEMPS REACHING AOA 70... UNABLE TO GET ANY SUBSTANTIVE CAPE WITH LLVLS DRIED BY MIXING AND WRMG MID LVLS UNDER UPR RDG. .LONG TERM (SUNDAY NIGHT THROUGH SATURDAY)... THE 500MB RIDGE LOOKS TO REMAIN IN PLACE OVER THE CWA UNTIL SUNDAY NIGHT. AT THAT TIME...SOUTHWESTERLY FLOW WILL BEGIN AS THE TROUGH OVER THE PACIFIC NORTHWEST SLOWLY EDGES EASTWARD TOWARDS THE GREAT LAKES REGION. CAN UNDERSTAND WHY THE TREND HAS CONTINUED...SLOWING THE ONSET OF PRECIPITATION DOWN MONDAY NIGHT AND TUESDAY. IN FACT...IT LOOKS MORE LIKE TUESDAY AFTERNOON BEFORE ANY SIGNIFICANT PRECIPITATION HITS THE WESTERN CWA. HPC GUIDANCE BACKS THIS SCENARIO UP. HOWEVER...THE 12Z RUNS OF THE NAM AND GFS HAVE QUICKENED THINGS UP ROUGHLY 6 HOURS FROM THEIR PREVIOUS RUNS. COMPARED TO THE OTHER OPTIONS...THE GFS WAS QUICKER. CAN NOT IGNORE THIS TREND...AND HAVE MADE SMALL ADJUSTMENTS WHILE ATTEMPTING TO NOT JUMP AROUND TOO MUCH DURING THIS PERIOD. THE PACIFIC TROUGH LOOKS TO SHIFT NE INSTEAD OF STRAIGHT EAST...RESULTING IN A MORE NORTHERLY BROAD SCALE TROUGH FOR US TUESDAY EVENING THROUGH WEDNESDAY AFTERNOON. STILL...CONTINUE TO LOOK FOR THE POTENTIAL FOR HEAVY RAIN AND THUNDERSTORMS AHEAD AND ALONG THE COLD FRONT AS IT SLIDES ACROSS. A HIGH PRESSURE RIDGE IS THEN FIGURED WEDNESDAY NIGHT THROUGH THE DAYTIME HOURS THURSDAY. THEN AGAIN...ANOTHER PACIFIC TROUGH SHOULD EDGE OVER THE WESTERN STATES TO NE MN/SOUTHERN ONTARIO BY 12Z SATURDAY. THE GFS IS THEN MUCH MORE PROGRESSIVE...TRYING TO DIVE THE TROUGH OVER THE SOUTHERN LAKES WHILE OTHER MODELS SEEM TO CONTINUE WITH A GENERAL E TO NE TRACK. FROM FRIDAY ON THE FORECAST BECOMES A BUGABOO. WITH MODEL VARIABILITY PRETTY HIGH...AND FORECAST CONFIDENCE RUNNING LOW AT THIS TIME FRAME...WILL OPT TO UTILIZED HPC GUIDANCE HEAVILY. THIS GENERALLY MEANT FOLLOWING A 00Z ECMWF FORECAST...WITH A BLEND OF ITS ENSEMBLE MEAN. && .HYDROLOGY (ISSUED AT 1050 AM EDT SATURDAY)... LOCATIONS THAT RECEIVED THE LEAST RAINFALL OVER THE LAST 24 HOURS...IN SOUTHERN AND EASTERN UPPER MICHIGAN...WERE ALSO THE LOCATIONS WITH THE SMALLEST SNOWMELT CONCERNS. LOCATIONS TO THE NORTH AND WEST RECEIVED BETWEEN A QUARTER TO A HALF INCH OF RAINFALL...ADDING TO SNOWMELT GOING INTO ALREADY HIGH RIVERS. HIGHS IN THE 40S SATURDAY...AND NEAR 60 ON SUNDAY AND MONDAY WILL RESULT IN RIVER LEVELS CONTINUING TO RISE. LATEST FORECASTS FROM THE RIVER FORECAST CENTER SHOW HIGHER CREST VALUES THAN PREVIOUSLY ISSUED FORECASTS. LOCATIONS WITH THE HIGHEST CONCERN INCLUDE THE CHOCOLAY RIVER NEAR HARVEY...AND THE STURGEON RIVER NEAR CHASSELL. AFTER DISCUSSION WITH THE CMX COUNTY EMERGENCY MANAGER AROUND NOON...OPTED TO ISSUE FLOOD WARNING FOR THE STURGEON RIVER AT CHASSELL WITH IMPENDING SLOW RISE TOWARD FLOOD STAGE. FOR CONTINUED UPDATES ON THE RIVERS... PLEASE SEE THE LATEST HYDROLOGIC STATEMENTS AND ANY FLOOD WATCHES OR WARNINGS THAT MAY BE ISSUED. IN ADDITION...FOR THE LATEST FORECAST PLEASE VISIT THE AHPS PAGE AND CLICK ON A RIVER SITE...THIS CAN BE FOUND UNDER THE RIVERS AND LAKES LINK AT WWW.WEATHER.GOV/UP && .AVIATION (FOR THE 00Z TAF ISSUANCE)... IT`S A VERY DIFFICULT FCST THIS EVENING. DRY AIR IS MAKING SOME INROADS FROM THE E ACROSS PORTIONS OF CNTRL UPPER MI PER SFC OBS WHICH HAVE SHOWN LOW CIGS BREAKING...BUT HIGH CLOUDS HAVE MADE IT IMPOSSIBLE TO SEE ON VIS SATELLITE IMAGERY EXACTLY WHERE AND HOW FAST THE LOW CLOUDS ARE CLEARING. IN ANYCASE...IT APPEARED LOW CLOUDS WOULD SCATTER OUT AT KCMX/KSAW THIS EVENING AS SOME DRYING OCCURS FROM THE E. HOWEVER...HAVE NOW OPTED FOR A MUCH MORE PESSIMISTIC FCST TONIGHT. SINCE SFC DWPTS ACROSS UPPER MI/LAKE SUPERIOR AND SURROUNDING REGION HAVE VERY SIMILAR VALUES TO CURRENT TEMPS AT KSAW/KCMX AND LOW-LEVEL WIND FLOW WILL RETAIN AN UPSLOPE COMPONENT THRU THE NIGHT AT BOTH SITES...IT SEEMS UNLIKELY THAT STRATUS (LIFR/IFR CIGS) WILL BREAK. ALSO...EXPECT VIS TO DROP SLOWLY TO IFR AS FOG DEVELOPS. POTENTIAL EXISTS FOR LIFR VIS IN FOG LATER IN THE NIGHT. SHOULD SEE CONDITIONS AT BOTH SITES IMPROVE TO VFR EARLY SUN AFTN. && .MARINE (FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)... EXPECT HIGH PRESSURE FROM JAMES BAY INTO QUEBEC TO REMAIN NEARLY STATIONARY THROUGH SUNDAY. MEANWHILE...LOW PRESSURE OVER SOUTHERN LAKE MICHIGAN IS EXPECTED TO DISSIPATE OVER THE SOUTHERN GREAT LAKES BY LATE SUNDAY. ALSO ON SUNDAY...LOW PRESSURE WILL DEVELOP OVER THE NORTHERN ROCKIES...THEN LIFT NORTHEAST TO HUDSON BAY BY TUESDAY EVENING AND DRAG A TROUGH OF LOW PRESSURE ACROSS THE WESTERN GREAT LAKES BY TUESDAY NIGHT. BEHIND THIS TROUGH...HIGH PRESSURE WILL SLIDE SOUTHEAST ACROSS THE GREAT LAKES REGION ON WEDNESDAY. A LOW PRESSURE SYSTEM DEVELOPING OVER THE CENTRAL PLAINS WILL THEN APPROACH THE WESTERN GREAT LAKES REGION ON THURSDAY. FOR THE MOST PART...WINDS SHOULD REMAIN UNDER 20 KTS INTO TUESDAY. EXPECT STRONGER SOUTH WINDS OVER THE EAST IN THE ADVANCE OF THE APPROACHING TROUGH ON TUESDAY/TUESDAY NIGHT. STRONGER WEST TO NORTHWEST WINDS WILL ARRIVE FOLLOWING THE PASSAGE OF THE TROUGH. && .MQT WATCHES/WARNINGS/ADVISORIES...NONE. && $$ SHORT TERM...KC LONG TERM...KF HYDROLOGY...TG/KC AVIATION...ROLFSON MARINE...KC mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GAYLORD MI 710 PM EDT SAT APR 19 2008 .AVIATION...LOW PRESSURE WILL STEADILY MOVE EAST ACROSS THE OHIO VALLEY. FAIR AMOUNT OF MID/HIGH CLOUDS AND HAZE ALOFT...BUT SHOWERS WILL STAY SOUTH OF ALL TAF SITES. WEATHER WILL REMAIN WARM...WITH LAKE BREEZES DEVELOPING AGAIN SUNDAY AFTERNOON AGAINST A BACKDROP OF OTHERWISE LIGHT EASTERLY WINDS. VFR THRU THE FORECAST. JZ && .DISCUSSION...ISSUED 303 PM SAT APR 19... LATEST RUC ANALYSIS AND VIS/IR/WV/RADAR IMAGERY SHOW AN UPPER LEVEL LOW SPINNING OVER THE SOUTHERN IL-IN BORDER AND A BROAD AREA OF SURFACE LOW PRESSURE OVER THE SOUTHERN GREAT LAKES. BANDS OF MID AND UPPER LEVEL CLOUD COVER CONTINUE TO ROTATE ACROSS NORTHERN MICHIGAN WITH HOLES IN THE CIRRUS SHIELD APPEARING EVERY NOW AND THEN. THESE CLOUDS HAVE NOT PREVENTED TEMPERATURES FROM RAPIDLY WARMING INTO THE LOW TO MID 70S INLAND. WITH PRECIP WELL TO THE SOUTH OVER FAR SOUTHERN LOWER MICHIGAN...MAIN FORECAST CONCERNS INCLUDE TEMPS AND SKY COVER TONIGHT...THEN SMALL CHANCES OF PRECIP ALONG LAKE BREEZE BOUNDARIES TOMORROW. TONIGHT...UPPER LOW WILL DRIFT SLIGHTLY SOUTH OF EAST AS IT CUTS ACROSS THE OHIO RIVER VALLEY TO THE CENTRAL APPALACHIANS. SPOKE OF UPPER LEVEL MOISTURE WILL PINWHEEL ACROSS NORTHERN MICHIGAN TONIGHT...BUT FORCING AND DEEP MOISTURE WILL REMAIN WELL SOUTH OF THE REGION. THAT LEAVES TEMPERATURES AND SKY COVER TO THINK ABOUT. LOWS LAST NIGHT DIPPED INTO THE MIDDLE AND UPPER 30S ACROSS NE LOWER WHERE CLEAR SKIES HUNG ON THE LONGEST. DO NOT THINK THAT WILL HAPPEN TONIGHT DUE TO THE CIRRUS SHIELD...EVEN THOUGH THIS CIRRUS WILL THIN OVERNIGHT ACROSS NORTHERN LOWER. SO HAVE KEPT LOWS SIMILAR TO LAST NIGHT EXCEPT RAISED THEM A FEW DEGREES OVER NE LOWER. LOWS IN THE 40S. TOMORROW...UPPER LOW WILL MEANDER ACROSS THE CENTRAL APPALACHIANS WHILE MID-LEVEL HEIGHTS SLOWLY BUILD ACROSS THE NORTHERN GREAT LAKES. NO LARGE-SCALE FORCING TO SPEAK UP WITH THE BUILDING RIDGE...BUT STILL HINTS THAT LOCALIZED CONVERGENCE WILL SETUP ACROSS THE SW CWA WITH PREVAILING EAST FLOW BUTTING HEADS AGAINST LAKE BREEZES OFF OF LAKE MICHIGAN AND GRAND TRAVERSE BAY. BOTH NAM/GFS SPIT OUT QPF CENTERED AROUND WEXFORD COUNTY...BUT THINK THIS IS MORE OF A BY-PRODUCT OF OVER-GENEROUS SURFACE DEWPOINTS...WHICH BOTH MODELS SHOW IN THE LOWER TO MID 50S. DEEP MIXING UP TO 775MB SUGGESTS DEWPOINTS WILL MIX OUT TO AROUND 48F. USING A TEMP OF 72F...THIS WOULD YIELD SKINNY ML CAPES AROUND 200 J/KG IN THE MORE MOIST NAM SOLUTION...WHILE THE DRIER GFS SUGGESTS TOO MUCH CIN WILL EXIST TO TRIGGER A SHOWER. GIVEN THE INCREASING SUBSIDENCE THROUGH THE DAY...LEAN MORE TOWARD THE DRIER SOLUTION AND WILL LEAVE POPS OUT OF THE FORECAST. ANOTHER WARM DAY ON TAP WITH HIGHS RANGING FROM THE MID 60S NORTH/NEAR LAKESHORES...TO THE LOWER 70S INLAND. MPC SUN NIGHT THRU MON NIGHT...RATHER QUIET PERIOD OF WX EXPECTED TO CONTINUE...THOUGH A FEW FCST CONCERNS REMAIN...NAMELY TEMPS MON AFTN ALONG WITH ANY SMALL PRECIP CHANCES THRU THE PERIOD. POTENT CLOSED LOW SPINNING OVR SOUTHERN IN THIS AFTN PROGGED TO SLIP INTO VIRGINIA BY EARLY MON...WITH BROAD SHORTWAVE RIDGING BUILDING ACRS THE LAKES IN ADVANCE OF NEXT UPSTREAM TROUGH OVR THE NORTHWEST. HOWEVER... CONCERN REGARDING POTENTIAL PRECIP STEMS FROM BROAD PLUME OF WRAP AROUND MOISTURE PROGGED TO ADVECT BACK INTO THE REGION SUN NIGHT TIMEFRAME...AS UPR GYRE ABLE TO TAP ADDITIONAL MOISTURE FROM THE ATLANTIC. INTERESTING TO NOTE BOTH NAM AND GFS SPIT OUT A HINT OF MEASURABLE PRECIP SUN NIGHT/EARLY MON THOUGH DIFFICULT TO FORESEE THIS GIVEN OVERALL LACK OF MID/UPR LEVEL MOISTURE AND FORCING...WITH ONLY SOME WEAK HINT OF CHANNELED VORT (REMNANTS OF CLOSED LOW TO THE SOUTH TODAY) HEADING NORTH THRU THE NIGHT. THUS WILL MAINTAIN DRY FCST AT THIS TIME. HEADING INTO MON AFTN...APPEARS ANOTHER WARM DAY ON TAP WITH DEVELOPING SOUTHERLY FLOW AHEAD OF APPROACHING UPR TROUGH...THOUGH OVERALL LACK OF MIXING PER LOW LEVEL RIDGE AXIS DRAPED OVERHEAD SHOULD KNOCK A FEW DEGREE OFF POTENTIAL HIGHS (READINGS MAINLY MID/UPR 60S LOOK GOOD). DESPITE GOOD HEATING AND LIKELY LAKE BREEZE CONVERGENCE ALONG THE LAKE MICHIGAN SIDE... DIFFICULT TO SEE CONVECTION (OTHER THAN A FAIRLY HEALTHY CU FIELD) FIRING DESPITE AN INCREASE IN BOUNDARY LAYER MOISTURE...AS MID LEVEL SUBSIDENCE INVERSION BUILDS THRU THE DAY. LATER PERIODS (TUE THRU SAT)...PATTERN TO REMAIN QUITE BLOCKY THRU THE EXTENDED PORTION OF THE FCST...OWING TO HIGHLY AMPLIFIED/ CLOSED MID LEVEL RIDGE ACRS CENTRAL/EASTERN ALASKA...IMPLYING SIGNIFICANT DOWNSTREAM TROUGHING INTO THE WESTERN CONUS. INDEED... THIS TYPE OF PATTERN IS WHAT THE MEDIUM RANGE GUIDANCE CONTINUES TO SUGGEST...WITH INITIAL CLOSED LOW (EVIDENT THIS AFTN NEAR THE BRITISH COLUMBIA/WASHINGTON STATE BORDER) AND ASSOCIATED ENERGY SHEARING OUT INTO THE NORTHERN PLAINS/UPR MIDWEST ON TUE...OWING TO BRIEF DISRUPTION OF BLOCKING FLOW ACRS THE EASTERN PACIFIC AS ENERGY UNDERCUTS THE RIDGE. END RESULT FOR NORTHERN MI WILL BE INCREASING CHANCES FOR PRECIP TUE NIGHT AS ASSOCIATED SFC FRONT AND WEAKENING FORCING SLIDES THRU THE REGION. WILL CONTINUE THUNDER MENTION AS WELL WITH EXPECTED DECENT MOISTURE TAP INTO THE AREA VIA OPEN GULF...AND MODEL PROGS OF SHOWALTER INDICES DIPPING WELL BELOW 0C ALONG WITH STEEPER MID LEVEL LAPSE RATE PLUME OVERHEAD. PONDERED BRINGING SMALL POPS BACK INTO THE PICTURE FOR TUE AFTN AS MOISTURE INCREASES AHEAD OF THE FRONT...WITH POTENTIAL FOR BRIEF CONVECTION TO POP AHEAD OF THE BOUNDARY GIVEN EXPECTED HEATING AND LIKELY LOW LEVEL WEAK UPSLOPE REGIME INTO THE HIGHER TERRAIN PER BACKING OF FLOW AHEAD OF THE FRONT...THOUGH ANYTHING ISOLATED AT BEST SO DRY FCST WILL CONTINUE. TEMPS TUE IFFY PENDING DEGREE OF SUN...THOUGH POTENTIAL IS THERE FOR A VERY WARM DAY WITH REGION IN THE THERMAL RIDGE AHEAD OF THE FRONT. WILL RUN WITH MID 60S TO LOWER 70S AREAWIDE. STILL LOOKS LIKE A DRY AND MORE SEASONABLE DAY ON TAP FOR THU AS LOW/MID LEVEL RIDGING AND ASSOCIATED SUBSIDENCE/DRYING TAKE HOLD. 00Z GUIDANCE NUMBERS APPEAR A BIT TOO COOL GIVEN EXPECTED SUN...SO WILL RUN WITH TEMPS UPR 50S TO MID 60S. THEREAFTER...GUIDANCE BEGINS TO DIVERGE ON AMPLITUDE OF ADDITIONAL WESTERN TROUGHING THU/FRI...THOUGH PATTERN RECOGNITION WITH DEEP LAYER/MERIDIONAL RIDGE BECOMING RE-ESTABLISHED ACRS ALASKA CERTAINLY ARGUES FOR THE ECMWF/GEFS MEAN SOLUTIONS OF A DEEPER WESTERN TROUGH. REGARDLESS OF EVENTUAL SOLUTION...IMPLICATION FOR THE CWA IS ADDITIONAL PRECIP CHANCES FRI/SAT TIMEFRAME AS LEE CYCLOGENESIS GETS GOING ON THE PLAINS...WITH ASSOCIATED COLD FRONT HEADING EAST BY THE WEEKEND. LAWRENCE && .APX WATCHES/WARNINGS/ADVISORIES... MI...NONE. LM...NONE. LH...NONE. LS...NONE. && $$ mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 350 PM EDT SAT APR 19 2008 .SYNOPSIS... 12Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW DEEPENING UPR TROF ALG THE W COAST AND BLDG RDG OVER THE E HALF OF NAMERICA. CUTOFF LO UNDER THE BLDG RDG IS MOVING E THRU THE OH VALLEY WHILE ANOTHER SHRTWV IS LIFTING INTO WRN LK SUP. INTERACTION OF THIS SHRTWV/ ASSOCIATED UPR DVGC/DPVA/H85-5 QVECTOR CNVGC WITH DEEPER MSTR SHOWN ON THE 12Z MPX RAOB IS CAUSING SCT -SHRA/QUITE A BIT OF LO CLD OVER THE NW HALF OF THE FA EARLY THIS AFTN. BUT 12Z GRB/APX RAOBS SHOW MUCH DRIER AIR IS PRESENT TO THE SE ABV LINGERING SHALLOW MSTR. WITH SE H85 WINDS BTWN CUTOFF LO IN THE OH VALLEY AND HUDSON BAY HI PRES...THIS DRY IS OVERSPRDG THE FA...HAS ENDED THE PCPN OVER THE SCNTRL AND E...AND IS TENDING TO DIMINISH THE SHRA COVG OVER THE NW. .SHORT TERM (TONIGHT AND SUNDAY)... FOR TNGT...GENERAL MSLP/UPR HGT RISES FCST OVER THE UPR LKS DOWNSTREAM OF DEEPENING TROF IN THE W. WITH PERSISTENT ELY FLOW BTWN HUDSON BAY HI AND DEPARTING CLOSED LO IN THE OH VALLEY...EXPECT DRIER AIR IN THAT DIRECTION TO CONTINUE MAKING INROADS ESE-WNW THRU THE FA. WL RESTRICT MENTION OF POPS THIS EVNG TO THE W BEFORE DROPPING MENTION OF PCPN EXCEPT OVER WRN LK SUP UNDER LINGERING DEEPER MSTR CLOSER TO INCRSGLY SHEARED SHRTWV IMPACTING THAT AREA. EVEN THOUGH THE MID LVLS WL BE DRYING OUT...SUSPECT THE LLVL MSTR WL BE HARDER TO DISLODGE. THIS LLVL MSTR WL BE MOST RESILIENT OVER THE NW IN AREAS WHERE LO CLDS HAVE LINGERED THRU THE DAY AND LIMITED INSOLATION/MIXING. SO WL FCST AREAS OF FOG TO DVLP DESPITE SOME LINGERING HI CLD. HOWEVER...CONDITIONS DON`T APPEAR IDEAL FOR DENSE FOG FORMATION WITH FCST RELATIVELY SHARP PRES GRADIENT BTWN HI TO THE N AND LO IN THE OH VALLEY. EXPECT ONLY PTCHY FOG OVER THE E CONSIDERING THE DEEPER MIXING EVIDENT THERE THIS AFTN. WL TEND TO UNDERCUT MOS FCST LO TEMPS OVER THE INTERIOR E CLOSER TO THE CORE OF THE DRIEST AIR. ON SUN...ACYC ENE FLOW WL DOMINATE THE UPR GRT LKS. WITH DRY AIR ABV THE SFC IN THE MRNG...INSOLATION SHOULD MIX OUT RADIATION FOG. BUT NE FLOW OFF LK SUP MIGHT TEND TO KEEP THE FOG/LO CLD MORE RESILIENT NEAR THE SHORE. DEEP MIXING TO H75 ON GFS FCST SDNGS (NAM/GFS BOTH SHOW H85 TEMPS ARND 10C) WOULD SUPPORT HI TEMPS APRCHG 70 AWAY FM LK MODERATION AS OBSVD IN NRN LWR MI THIS AFTN. BUT TEMPS NEAR LK SUP/ THE GREEN BAY SHOULD BE QUITE A BIT COOLER. SINCE GFS/NAM GENERATE SOME LGT QPF OVER NRN WI BTWN 18Z-24Z...CHECKED FOR THE POTENTIAL FOR SOME INSTABILITY SHRA. BUT EVEN FOR HI TEMPS REACHING AOA 70... UNABLE TO GET ANY SUBSTANTIVE CAPE WITH LLVLS DRIED BY MIXING AND WRMG MID LVLS UNDER UPR RDG. && .LONG TERM (SUNDAY NIGHT THROUGH SATURDAY)... THE 500MB RIDGE LOOKS TO REMAIN IN PLACE OVER THE CWA UNTIL SUNDAY NIGHT. AT THAT TIME...SOUTHWESTERLY FLOW WILL BEGIN AS THE TROUGH OVER THE PACIFIC NORTHWEST SLOWLY EDGES EASTWARD TOWARDS THE GREAT LAKES REGION. CAN UNDERSTAND WHY THE TREND HAS CONTINUED...SLOWING THE ONSET OF PRECIPITATION DOWN MONDAY NIGHT AND TUESDAY. IN FACT...IT LOOKS MORE LIKE TUESDAY AFTERNOON BEFORE ANY SIGNIFICANT PRECIPITATION HITS THE WESTERN CWA. HPC GUIDANCE BACKS THIS SCENARIO UP. HOWEVER...THE 12Z RUNS OF THE NAM AND GFS HAVE QUICKENED THINGS UP ROUGHLY 6 HOURS FROM THEIR PREVIOUS RUNS. COMPARED TO THE OTHER OPTIONS...THE GFS WAS QUICKER. CAN NOT IGNORE THIS TREND...AND HAVE MADE SMALL ADJUSTMENTS WHILE ATTEMPTING TO NOT JUMP AROUND TOO MUCH DURING THIS PERIOD. THE PACIFIC TROUGH LOOKS TO SHIFT NE INSTEAD OF STRAIGHT EAST...RESULTING IN A MORE NORTHERLY BROAD SCALE TROUGH FOR US TUESDAY EVENING THROUGH WEDNESDAY AFTERNOON. STILL...CONTINUE TO LOOK FOR THE POTENTIAL FOR HEAVY RAIN AND THUNDERSTORMS AHEAD AND ALONG THE COLD FRONT AS IT SLIDES ACROSS. A HIGH PRESSURE RIDGE IS THEN FIGURED WEDNESDAY NIGHT THROUGH THE DAYTIME HOURS THURSDAY. THEN AGAIN...ANOTHER PACIFIC TROUGH SHOULD EDGE OVER THE WESTERN STATES TO NE MN/SOUTHERN ONTARIO BY 12Z SATURDAY. THE GFS IS THEN MUCH MORE PROGRESSIVE...TRYING TO DIVE THE TROUGH OVER THE SOUTHERN LAKES WHILE OTHER MODELS SEEM TO CONTINUE WITH A GENERAL E TO NE TRACK. FROM FRIDAY ON THE FORECAST BECOMES A BUGABOO. WITH MODEL VARIABILITY PRETTY HIGH...AND FORECAST CONFIDENCE RUNNING LOW AT THIS TIME FRAME...WILL OPT TO UTILIZED HPC GUIDANCE HEAVILY. THIS GENERALLY MEANT FOLLOWING A 00Z ECMWF FORECAST...WITH A BLEND OF ITS ENSEMBLE MEAN. && .AVIATION (FOR THE 18Z TAF ISSUANCE)... EXPECT SLOW IMPROVEMENT IN CIG/VSBY TDAY WITH DIURNAL HTG AND ADVECTION OF DRY AIR JUST ABV SHALLOW MOIST LYR AS SHOWN ON THE 12Z APX RAOB/RECENT TAMDAR SDNG FM CIU. CONDITIONS WL BE SLOWEST TO IMPROVE AT CMX FARTHER FM THIS DRY AIR THAT IS ARRIVING FM THE ESE... AND LO CLDS ARE NOT LIKELY TO BREAK UP THERE UNTIL THIS EVNG. WITH CONTINUED DRYING ALF AND SNOW MELT TNGT...EXPECT MORE RADIATION FOG TO DVLP OVERNGT WITH LIFR VSBYS LIKELY. BEST CHC FOR LO IFR CIG WL BE AT SAW WITH FVRBL UPSLOPE NNE WIND COMPONENT. && .MARINE (FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)... EXPECT HIGH PRESSURE FROM JAMES BAY INTO QUEBEC TO REMAIN NEARLY STATIONARY THROUGH SUNDAY. MEANWHILE...LOW PRESSURE OVER SOUTHERN LAKE MICHIGAN IS EXPECTED TO DISSIPATE OVER THE SOUTHERN GREAT LAKES BY LATE SUNDAY. ALSO ON SUNDAY...LOW PRESSURE WILL DEVELOP OVER THE NORTHERN ROCKIES...THEN LIFT NORTHEAST TO HUDSON BAY BY TUESDAY EVENING AND DRAG A TROUGH OF LOW PRESSURE ACROSS THE WESTERN GREAT LAKES BY TUESDAY NIGHT. BEHIND THIS TROUGH...HIGH PRESSURE WILL SLIDE SOUTHEAST ACROSS THE GREAT LAKES REGION ON WEDNESDAY. A LOW PRESSURE SYSTEM DEVELOPING OVER THE CENTRAL PLAINS WILL THEN APPROACH THE WESTERN GREAT LAKES REGION ON THURSDAY. FOR THE MOST PART...WINDS SHOULD REMAIN UNDER 20 KTS INTO TUESDAY. EXPECT STRONGER SOUTH WINDS OVER THE EAST IN THE ADVANCE OF THE APPROACHING TROUGH ON TUESDAY/TUESDAY NIGHT. STRONGER WEST TO NORTHWEST WINDS WILL ARRIVE FOLLOWING THE PASSAGE OF THE TROUGH. && .HYDROLOGY (ISSUED AT 1050 AM EDT SATURDAY)... LOCATIONS THAT RECEIVED THE LEAST RAINFALL OVER THE LAST 24 HOURS...IN SOUTHERN AND EASTERN UPPER MICHIGAN...WERE ALSO THE LOCATIONS WITH THE SMALLEST SNOWMELT CONCERNS. LOCATIONS TO THE NORTH AND WEST RECEIVED BETWEEN A QUARTER TO A HALF INCH OF RAINFALL...ADDING TO SNOWMELT GOING INTO ALREADY HIGH RIVERS. HIGHS IN THE 40S SATURDAY...AND NEAR 60 ON SUNDAY AND MONDAY WILL RESULT IN RIVER LEVELS CONTINUING TO RISE. LATEST FORECASTS FROM THE RIVER FORECAST CENTER SHOW HIGHER CREST VALUES THAN PREVIOUSLY ISSUED FORECASTS. LOCATIONS WITH THE HIGHEST CONCERN INCLUDE THE CHOCOLAY RIVER NEAR HARVEY...AND THE STURGEON RIVER NEAR CHASSELL. AFTER DISCUSSION WITH THE CMX COUNTY EMERGENCY MANAGER AROUND NOON...OPTED TO ISSUE FLOOD WARNING FOR THE STURGEON RIVER AT CHASSELL WITH IMPENDING SLOW RISE TOWARD FLOOD STAGE. FOR CONTINUED UPDATES ON THE RIVERS... PLEASE SEE THE LATEST HYDROLOGIC STATEMENTS AND ANY FLOOD WATCHES OR WARNINGS THAT MAY BE ISSUED. IN ADDITION...FOR THE LATEST FORECAST PLEASE VISIT THE AHPS PAGE AND CLICK ON A RIVER SITE...THIS CAN BE FOUND UNDER THE RIVERS AND LAKES LINK AT WWW.WEATHER.GOV/UP && .MQT WATCHES/WARNINGS/ADVISORIES...NONE. && $$ SHORT TERM...KC LONG TERM...KF AVIATION...KC MARINE...KC HYDROLOGY...TG/KC mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GAYLORD MI 303 PM EDT SAT APR 19 2008 .DISCUSSION...LATEST RUC ANALYSIS AND VIS/IR/WV/RADAR IMAGERY SHOW AN UPPER LEVEL LOW SPINNING OVER THE SOUTHERN IL-IN BORDER AND A BROAD AREA OF SURFACE LOW PRESSURE OVER THE SOUTHERN GREAT LAKES. BANDS OF MID AND UPPER LEVEL CLOUD COVER CONTINUE TO ROTATE ACROSS NORTHERN MICHIGAN WITH HOLES IN THE CIRRUS SHIELD APPEARING EVERY NOW AND THEN. THESE CLOUDS HAVE NOT PREVENTED TEMPERATURES FROM RAPIDLY WARMING INTO THE LOW TO MID 70S INLAND. WITH PRECIP WELL TO THE SOUTH OVER FAR SOUTHERN LOWER MICHIGAN...MAIN FORECAST CONCERNS INCLUDE TEMPS AND SKY COVER TONIGHT...THEN SMALL CHANCES OF PRECIP ALONG LAKE BREEZE BOUNDARIES TOMORROW. TONIGHT...UPPER LOW WILL DRIFT SLIGHTLY SOUTH OF EAST AS IT CUTS ACROSS THE OHIO RIVER VALLEY TO THE CENTRAL APPALACHIANS. SPOKE OF UPPER LEVEL MOISTURE WILL PINWHEEL ACROSS NORTHERN MICHIGAN TONIGHT...BUT FORCING AND DEEP MOISTURE WILL REMAIN WELL SOUTH OF THE REGION. THAT LEAVES TEMPERATURES AND SKY COVER TO THINK ABOUT. LOWS LAST NIGHT DIPPED INTO THE MIDDLE AND UPPER 30S ACROSS NE LOWER WHERE CLEAR SKIES HUNG ON THE LONGEST. DO NOT THINK THAT WILL HAPPEN TONIGHT DUE TO THE CIRRUS SHIELD...EVEN THOUGH THIS CIRRUS WILL THIN OVERNIGHT ACROSS NORTHERN LOWER. SO HAVE KEPT LOWS SIMILAR TO LAST NIGHT EXCEPT RAISED THEM A FEW DEGREES OVER NE LOWER. LOWS IN THE 40S. TOMORROW...UPPER LOW WILL MEANDER ACROSS THE CENTRAL APPALACHIANS WHILE MID-LEVEL HEIGHTS SLOWLY BUILD ACROSS THE NORTHERN GREAT LAKES. NO LARGE-SCALE FORCING TO SPEAK UP WITH THE BUILDING RIDGE...BUT STILL HINTS THAT LOCALIZED CONVERGENCE WILL SETUP ACROSS THE SW CWA WITH PREVAILING EAST FLOW BUTTING HEADS AGAINST LAKE BREEZES OFF OF LAKE MICHIGAN AND GRAND TRAVERSE BAY. BOTH NAM/GFS SPIT OUT QPF CENTERED AROUND WEXFORD COUNTY...BUT THINK THIS IS MORE OF A BY-PRODUCT OF OVER-GENEROUS SURFACE DEWPOINTS...WHICH BOTH MODELS SHOW IN THE LOWER TO MID 50S. DEEP MIXING UP TO 775MB SUGGESTS DEWPOINTS WILL MIX OUT TO AROUND 48F. USING A TEMP OF 72F...THIS WOULD YIELD SKINNY ML CAPES AROUND 200 J/KG IN THE MORE MOIST NAM SOLUTION...WHILE THE DRIER GFS SUGGESTS TOO MUCH CIN WILL EXIST TO TRIGGER A SHOWER. GIVEN THE INCREASING SUBSIDENCE THROUGH THE DAY...LEAN MORE TOWARD THE DRIER SOLUTION AND WILL LEAVE POPS OUT OF THE FORECAST. ANOTHER WARM DAY ON TAP WITH HIGHS RANGING FROM THE MID 60S NORTH/NEAR LAKESHORES...TO THE LOWER 70S INLAND. MPC SUN NIGHT THRU MON NIGHT...RATHER QUIET PERIOD OF WX EXPECTED TO CONTINUE...THOUGH A FEW FCST CONCERNS REMAIN...NAMELY TEMPS MON AFTN ALONG WITH ANY SMALL PRECIP CHANCES THRU THE PERIOD. POTENT CLOSED LOW SPINNING OVR SOUTHERN IN THIS AFTN PROGGED TO SLIP INTO VIRGINIA BY EARLY MON...WITH BROAD SHORTWAVE RIDGING BUILDING ACRS THE LAKES IN ADVANCE OF NEXT UPSTREAM TROUGH OVR THE NORTHWEST. HOWEVER... CONCERN REGARDING POTENTIAL PRECIP STEMS FROM BROAD PLUME OF WRAP AROUND MOISTURE PROGGED TO ADVECT BACK INTO THE REGION SUN NIGHT TIMEFRAME...AS UPR GYRE ABLE TO TAP ADDITIONAL MOISTURE FROM THE ATLANTIC. INTERESTING TO NOTE BOTH NAM AND GFS SPIT OUT A HINT OF MEASURABLE PRECIP SUN NIGHT/EARLY MON THOUGH DIFFICULT TO FORESEE THIS GIVEN OVERALL LACK OF MID/UPR LEVEL MOISTURE AND FORCING...WITH ONLY SOME WEAK HINT OF CHANNELED VORT (REMNANTS OF CLOSED LOW TO THE SOUTH TODAY) HEADING NORTH THRU THE NIGHT. THUS WILL MAINTAIN DRY FCST AT THIS TIME. HEADING INTO MON AFTN...APPEARS ANOTHER WARM DAY ON TAP WITH DEVELOPING SOUTHERLY FLOW AHEAD OF APPROACHING UPR TROUGH...THOUGH OVERALL LACK OF MIXING PER LOW LEVEL RIDGE AXIS DRAPED OVERHEAD SHOULD KNOCK A FEW DEGREE OFF POTENTIAL HIGHS (READINGS MAINLY MID/UPR 60S LOOK GOOD). DESPITE GOOD HEATING AND LIKELY LAKE BREEZE CONVERGENCE ALONG THE LAKE MICHIGAN SIDE... DIFFICULT TO SEE CONVECTION (OTHER THAN A FAIRLY HEALTHY CU FIELD) FIRING DESPITE AN INCREASE IN BOUNDARY LAYER MOISTURE...AS MID LEVEL SUBSIDENCE INVERSION BUILDS THRU THE DAY. LATER PERIODS (TUE THRU SAT)...PATTERN TO REMAIN QUITE BLOCKY THRU THE EXTENDED PORTION OF THE FCST...OWING TO HIGHLY AMPLIFIED/ CLOSED MID LEVEL RIDGE ACRS CENTRAL/EASTERN ALASKA...IMPLYING SIGNIFICANT DOWNSTREAM TROUGHING INTO THE WESTERN CONUS. INDEED... THIS TYPE OF PATTERN IS WHAT THE MEDIUM RANGE GUIDANCE CONTINUES TO SUGGEST...WITH INITIAL CLOSED LOW (EVIDENT THIS AFTN NEAR THE BRITISH COLUMBIA/WASHINGTON STATE BORDER) AND ASSOCIATED ENERGY SHEARING OUT INTO THE NORTHERN PLAINS/UPR MIDWEST ON TUE...OWING TO BRIEF DISRUPTION OF BLOCKING FLOW ACRS THE EASTERN PACIFIC AS ENERGY UNDERCUTS THE RIDGE. END RESULT FOR NORTHERN MI WILL BE INCREASING CHANCES FOR PRECIP TUE NIGHT AS ASSOCIATED SFC FRONT AND WEAKENING FORCING SLIDES THRU THE REGION. WILL CONTINUE THUNDER MENTION AS WELL WITH EXPECTED DECENT MOISTURE TAP INTO THE AREA VIA OPEN GULF...AND MODEL PROGS OF SHOWALTER INDICES DIPPING WELL BELOW 0C ALONG WITH STEEPER MID LEVEL LAPSE RATE PLUME OVERHEAD. PONDERED BRINGING SMALL POPS BACK INTO THE PICTURE FOR TUE AFTN AS MOISTURE INCREASES AHEAD OF THE FRONT...WITH POTENTIAL FOR BRIEF CONVECTION TO POP AHEAD OF THE BOUNDARY GIVEN EXPECTED HEATING AND LIKELY LOW LEVEL WEAK UPSLOPE REGIME INTO THE HIGHER TERRAIN PER BACKING OF FLOW AHEAD OF THE FRONT...THOUGH ANYTHING ISOLATED AT BEST SO DRY FCST WILL CONTINUE. TEMPS TUE IFFY PENDING DEGREE OF SUN...THOUGH POTENTIAL IS THERE FOR A VERY WARM DAY WITH REGION IN THE THERMAL RIDGE AHEAD OF THE FRONT. WILL RUN WITH MID 60S TO LOWER 70S AREAWIDE. STILL LOOKS LIKE A DRY AND MORE SEASONABLE DAY ON TAP FOR THU AS LOW/MID LEVEL RIDGING AND ASSOCIATED SUBSIDENCE/DRYING TAKE HOLD. 00Z GUIDANCE NUMBERS APPEAR A BIT TOO COOL GIVEN EXPECTED SUN...SO WILL RUN WITH TEMPS UPR 50S TO MID 60S. THEREAFTER...GUIDANCE BEGINS TO DIVERGE ON AMPLITUDE OF ADDITIONAL WESTERN TROUGHING THU/FRI...THOUGH PATTERN RECOGNITION WITH DEEP LAYER/MERIDIONAL RIDGE BECOMING RE-ESTABLISHED ACRS ALASKA CERTAINLY ARGUES FOR THE ECMWF/GEFS MEAN SOLUTIONS OF A DEEPER WESTERN TROUGH. REGARDLESS OF EVENTUAL SOLUTION...IMPLICATION FOR THE CWA IS ADDITIONAL PRECIP CHANCES FRI/SAT TIMEFRAME AS LEE CYCLOGENESIS GETS GOING ON THE PLAINS...WITH ASSOCIATED COLD FRONT HEADING EAST BY THE WEEKEND. LAWRENCE && .AVIATION... /ISSUED 100 PM EDT SAT APR 19 2008/ CIRRUS SHIELD WITH A FEW MID-LEVEL CLOUDS MIXED IN WILL PERSIST OVER THE AREA THROUGH THE TAF PERIOD AS LOW PRESSURE PASSES TO THE SOUTH. THIS CIRRUS WILL THIN TOMORROW MORNING. OVERALL...VFR CONDITIONS WILL REMAIN PRESENT. MPC && .APX WATCHES/WARNINGS/ADVISORIES... MI...NONE. LM...NONE. LH...NONE. LS...NONE. && $$ mi AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE MARQUETTE MI 140 AM EDT SAT APR 19 2008 UPDATED AVIATION DISCUSSION FOR 06Z TAFS .UPDATE (ISSUED AT 1051 PM EDT)... WATER VAPOR IMAGERY AND RUC ANALYSIS SHOW MID/UPPER LEVEL LOW DRIFTING E THRU MISSOURI. LIKE LAST NIGHT...UPPER JET STREAK EXTENDS ROUGHLY FROM NE MN/LAKE SUPERIOR ENE ACROSS ONTARIO. UPPER DIVERGENCE IN THE RIGHT ENTRANCE OF JET AND CORRESPONDING BAND OF MIDLEVEL FRONTOGENESIS IS SUPPORTING PCPN ACROSS CNTRL/NRN WI INTO CNTRL UPPER MI IN DEEP MOISTURE BROUGHT N BY MIDLEVEL LOW. AS MIDLEVEL LOW CONTINUES EWD TONIGHT/SAT...LOW-LEVEL WINDS WILL BECOME MORE ERLY...ADVECTING DRIER AIR WWD INTO UPPER MI. AT THE SAME TIME...UPPER JET WILL BE WEAKENING. SO...LAST SURGE OF -RA WILL OCCUR DURING THE NIGHT...AND MAINLY OVER THE W HALF OF UPPER MI. GOING FCST HAS THIS COVERED WELL WITH HIGHEST POPS OVER WRN UPPER MI. LATER IN THE NIGHT...OPTED TO LWR POPS ACROSS PORTIONS OF CNTRL UPPER MI AS DRIER AIR IS ALREADY BEGINNING TO AFFECT HOW FAR E PCPN IS DEVELOPING ACROSS ERN WI. ALSO...EXPANDED AREA OF NO PCPN OVER THE FAR ERN FCST AREA. CARRIED THIS DRIER TREND INTO SAT BY REMOVING MENTION OF PCPN ROUGHLY E OF A KMQT TO KMNN LINE. FINAL NOTE...HIT FOG MENTION HARDER OVER NCNTRL UPPER MI UNDER MOIST UPSLOPING NE FLOW WHICH IS RESULTING IN MORE WIDESPREAD FOG WITH SOME PATCHY DENSE FOG. && .SYNOPSIS (ISSUED AT 515 PM EDT)... THE WEATHER OVER THE CNTRL CONUS WAS DOMINATED BY A MID/UPPER LEVEL LOW OVER NW MO. UPSTREAM ANOTHER H5 LOW WAS LOCATED OVER SRN BC WILL HAVE WEATHER IMPACTS INTO THE CNTRL CONUS NEXT WEEK AS IT SLIDES EAST. AT THE SFC...WEAK NE FLOW PREVAILED OVER THE REGION BTWN LOW PRES OVER SRN IA AND A RIDGE FROM NE CANADA INTO NW MN. RADARS INDICATED A LARGE AREA OF MAINLY LIGHT RAIN FROM NE IA THROUGH CNTRL WI...CNTRL UPPER MI AND ERN LAKE SUPERIOR. THE PCPN WAS SUPPORTED BY A 850-700 MB FGEN/DEFORMATION AND 300K ISENTROPIC ASCENT ALONG AND NORTH OF THE 850 MB FRONT. MOISTURE FUNNELING INTO THE PCPN ZONE WAS ABUNDANT WITH THE 12Z KGRB SOUNDING SHOWING PWAT TO NEAR AN INCH. && .SHORT TERM (TONIGHT AND SATURDAY ISSUED AT 515 PM EDT)... ALTHOUGH THE MID LEVEL LOW IS FCST TO SLIDE TO THE ESE INTO THE OHIO VALLEY THE DEFORMATION ZONE PCPN INTO CNTRL UPPER MI IS EXPECTED TO PERSIST WITH ONLY A SLOW SHIFT INTO THE MAINLY THE W HALF OF THE CWA. OVER THE E HALF...MAINLY DRY WEATHER IS EXPECTED. THE FCST GENERALLY FOLLOWED A BLEND OF THE 12Z NAM/GFS AND LCL HIGH RES WRF WITH THE PCPN PATTERN/POPS AND QPF. WITH 850 MB TEMPS TO AROUND 10C...AND POTENTIAL FOR BETTER INSOLATION...TEMPS ARE EXPECTED TO CLIMB INTO THE LOWER 60S. OTHERWISE...THICKER CLOUDS AND PCPN WEST SHOULD LIMIT MAX READINGS CLOSER TO 50. MDLS SUGGEST THAT THE FORCING WILL WEAKEN SAT...SO THAT THE MODEST PCPN SHOULD TAPER OFF. OVERALL QPF VALUES SHOULD REMAIN IN THE 0.25 TO .50 INCH RANGE TONIGHT AND REMAIN BLO A 0.25 INCH SATURDAY. .LONG TERM (SATURDAY NIGHT THROUGH FRIDAY)... THE CWA WILL BE IN A COL...WITH GENERAL HIGH PRESSURE BOTH SATURDAY AND SUNDAY...AS TWO 500MB LOWS AFFECT OTHER PORTIONS OF THE NATION. THE FIRST WILL SLIDE FROM THE MID MISSISSIPPI VALLEY TO THE MID OHIO VALLEY. THE SECOND LOW...CURRENTLY OVER THE COAST MOUNTAINS OF WESTERN BRITISH COLUMBIA WILL CONTINUE TO ROTATE ALONG THE PACIFIC NORTHWEST. SW FLOW WILL BEGIN AND STRENGTHEN SUNDAY NIGHT AS THE PACIFIC NORTHWEST TROUGH SLIDES TO CENTRAL SASKATCHEWAN TUESDAY AFTERNOON...AND THEN TO HUDSON BAY BY WEDNESDAY AFTERNOON. CONTINUE TO GO SLOWER THAN A DAY AGO...WITH NO SIGNIFICANT PRECIPITATION FIGURED SUNDAY AND MONDAY. THIS SW FLOW ALOFT WILL BRING ABOUT COOLER THAN NORMAL TEMPERATURES ALONG WITH AN INCREASED CHANCE FOR WET WEATHER THROUGH MID WEEK. ALONG AND JUST AHEAD OF THE COLD FRONT...THE POTENTIAL EXISTS FOR MODERATE TO HEAVY RAINFALL PARTICULARLY WITH ANY THUNDERSTORMS THAT DEVELOP...MAINLY TUESDAY MORNING THROUGH TUESDAY AFTERNOON...AS THE SURFACE LOW OVER THE SOUTHERN PLAINS TUESDAY MORNING SLIDES NORTHEASTWARD TO WESTERN LAKE SUPERIOR BY LATE TUESDAY AFTERNOON. THE COLD FRONT IS EXPECTED TO SLIDE EAST OF THE CWA SHORTLY AFTER MIDNIGHT TUESDAY NIGHT. WE WILL NEED TO CONTINUE TO MONITOR HIGH RUNNING RIVERS THROUGH THIS PERIOD...AS ADDITIONAL RAINFALL COULD POSE A THREAT TO ALREADY SWOLLEN RIVERS AND STREAMS. HIGH PRESSURE WILL SLIDE IN AT THE SFC ON WEDNESDAYS...STILL WITH A BROAD-SCALE TROUGH AT 500MB. INCREASED AFTERNOON HIGH TEMPS ABOUT 5 DEGREES FOR WEDNESDAY...AS COLDER AIR KEEPS NORTH OF THE AREA WITH 850MB TEMPERATURES NOT DIPPING BELOW 0C UNTIL THURSDAY EVENING. FOR TUESDAY THROUGH FRIDAY...HPC GUIDANCE WAS A BLEND OF THE 00Z ECMWF ENSEMBLE MEAN AND 00Z NCEP GLOBAL ENSEMBLE MEAN...WITH LESS WEIGHTING TO THE OPERATIONAL 06Z-12Z GFS/00Z ECMWF/00Z UKMET. && .HYDROLOGY... PCPN COMBINED WITH CONTINUED MILD TEMPS FOR SNOWMELT...READINGS AROUND 40F TONIGHT AND AROUND 50F SAT...WILL LEAD TO STEADY CLIMB IN RIVER LEVELS ESPECIALLY OVER THE WEST HALF. FOR CONTINUED UPDATES ON THE RIVERS...PLEASE SEE THE LATEST HYDROLOGIC STATEMENTS AND ANY FLOOD WATCHES OR WARNINGS THAT MAY BE ISSUED. IN ADDITION...FOR THE LATEST FORECAST PLEASE VISIT THE AHPS PAGE AND CLICK ON A RIVER SITE...THIS CAN BE FOUND UNDER THE RIVERS AND LAKES LINK AT WWW.WEATHER.GOV/UP && .AVIATION (FOR THE 06Z TAF ISSUANCE)... CIGS AND/OR VIS AT KCMX AND KSAW HAVE CRASHED TO LIFR/VLIFR DURING THE EVENING. SEE LITTLE REASON FOR CONDITIONS TO IMPROVE DURING THE NIGHT WITH ABUNDANT LOW-LEVEL MOISTURE OVER THE AREA. CONDITIONS WILL BE WORST AT KSAW WITH PERSISTENT VLIFR VIS IN FOG UNDER UPSLOPING NE WINDS. IMPROVEMENT SHOULD BEGIN AT KSAW MID TO LATE MORNING WITH CONDITIONS TRENDING TO VFR IN THE AFTN AS DRIER AIR ARRIVES FROM THE E. AT KCMX...EXPECT OCCASIONAL -RA AND FOG TO KEEP VIS MOSTLY IN THE IFR RANGE THRU THE NIGHT. LIFR CIGS SHOULD BE THE RULE THRU MID MORNING WITH IMPROVEMENT TO MVFR BY MID AFTN AS -RA DIMINISHES/ENDS. VFR CONDITIONS EXPECTED AT KCMX IN THE EVENING. && .MARINE (FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)... HIGH PRESSURE GRADUALLY SHIFTS NORTHEAST OF LAKE SUPERIOR THROUGH SUNDAY...WITH WINDS AT OR LESS THAN 20KT. STRONGER SE WINDS UP TO 30 KT COULD OCCUR ON TUESDAY AHEAD OF A COLD FRONT APPROACHING FROM THE PLAINS. && .MQT WATCHES/WARNINGS/ADVISORIES...NONE. && $$ UPDATE...ROLFSON SYNOPSIS/SHORT TERM...JLB LONG TERM...KF HYDROLOGY...JLB AVIATION...ROLFSON MARINE...JLB mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN 1155 PM CDT SAT APR 19 2008 .PREV DISCUSSION.../ISSUED 350 PM CDT SAT APR 19 2008/ LOW PRESSURE CONTINUES TO DRIFT SLOWLY EASTWARD ACROSS THE LOWER GREAT LAKES. A FEW SHOWERS HAVE DEVELOPED THIS AFTERNOON ACROSS THE WI CWA ALONG A TROF AXIS. HELPING MATTERS IS STRONG HEATING THAT HAS DEVELOPED TO THE EAST AND SOUTH OF KEAU WITH SOME CLEARING. THERMAL GRADIENT ACROSS THE WESTERN HALF OF WI ABOUT 20 DEGREES ATTM. RUC BEST LI INTO THE EVENING AROUND ZERO SO WILL MENTION A FEW SHOWERS AND ISOLATED THUNDER THROUGH THE EVENING. NEXT CONCERN IS FOG POTENTIAL OVERNIGHT. BELIEF IS THAT THE LOW LEVEL FLOW WILL BECOME MORE EASTERLY OVERNIGHT DRAGGING SOME OF THE LOW CLOUDS INTO THE WESTERN CWA WHILE MAINTAINING A GOOD DEAL OF CLOUDINESS ELSEWHERE. DUE TO THE RAINS OVER WI AND SOUTH CENTRAL AREAS OF MN...AREAS OF FOG SHOULD OCCUR AGAIN TONIGHT. HOWEVER..IT COULD BECOME DENSE IF THE LOW CLOUDS WOULD DIMINISH DURING THE NIGHT. THIS LEADS INTO SUNDAY ON HOW HIGH AFTERNOON TEMPERATURES WILL GET IF PARTLY TO MOSTLY CLOUDY SKIES PREVAIL. NAM CU RULE IS QUITE NEGATIVE OVER EASTERN MN AND WEST CENTRAL WI...SO CUT BACK A LITTLE ON THE HIGH TEMPERATURES OVER THE EASTERN HALF OF THE CWA. THINGS REMAIN PRETTY MUCH ON TRACK WITH LOW PRESSURE AND A COLD FRONT APPROACHING WESTERN MN SUNDAY NIGHT AND THEN MOVING TO NEAR THE MN/WI BORDER BY MONDAY NIGHT. MAIN CHANGES TODAY WERE TO TIGHTEN UP ON THE POPS AND KEEP THEM CONFINED TO THE FAR WEST SUNDAY NIGHT WHERE SOME ELEVATED INSTABILITY DEVELOPS AND THEN NOT ALLOW THINGS TO GET TO FAR TO THE EAST TOO FAST ON MONDAY. STILL LOOKS GOOD FOR SHOWERS AND THUNDERSTORMS ALONG THE FRONT...ESPECIALLY EASTERN MN LATE MONDAY AFTERNOON AND EVENING AND THEN SPREADING INTO WI DURING THE NIGHT. THE FRONT BECOMES NEARLY STATIONARY ACROSS WEST CENTRAL WI BY TUESDAY MORNING AS LOW PRESSURE BEGINS TO RIDE NORTHEAST ALONG THE FRONT. PRECIPITATION CHANCES REMAIN HIGH OVER THE EASTERN CWA UNTIL TUESDAY EVENING. CAPE VALUES MODEST ON MONDAY AND LOW LEVEL SHEAR IS DIMINISHING MONDAY AFTERNOON. WHAT IS REALLY INTERESTING IS THE COUPLED JET THAT DEVELOPS ACROSS OUR AREA MONDAY NIGHT AND TUESDAY...GIVING THE EASTERN CWA QUITE A BIT OF DIFFERENTIAL LAYER DIVERGENCE. THIS WILL BE A PERIOD THAT WILL NEED TO BE MONITORED NOT ONLY FOR SEVERE WEATHER BUT HEAVY RAINFALL. A BREAK IN THE RAIN ON WEDNESDAY AS HIGH PRESSURE MOVES BY THEN A MORE VIGOROUS LOW WILL BE MOVING IN FROM THE CENTRAL PLAINS THURSDAY AND FRIDAY WITH SOME PRETTY GOOD APRIL SHOWERS AND THUNDERSTORMS. && .AVIATION.../06Z TAF ISSUANCE/ MAINLY MVFR CIGS IN PLACE UNDER SURFACE RIDGE OVER ALL BUT KAXN. DRIER AIR WAS ADVECTING INTO PARTS OF EAST CENTRAL MN...BUT LO LEVEL FLOW WILL GRADUALLY TURN MORE ESE TOWARD MORNING. EXPECT CEILINGS TO SPREAD NWRD OVER REST OF CWA OVERNIGHT AND SOME LOWERING INTO IFR CATEGORY IS EXPECTED OVER SOUTH CENTRAL MN. AS SE FLOW INCREASES DURING SUNDAY...LOWER CEILINGS WILL CONTINUE TO LIFT INTO CENTRAL AND NW MN WITH CLEARING OVER WEST CENTRAL WISCONSIN AND SOUTH CENTRAL MN. EXPECT VFR CONDITIONS UNDER MAINLY HIGH MAINLY HIGH CLOUDS AFTER 00Z. && .MP WATCHES/WARNINGS/ADVISORIES... MN...NONE. WI...NONE. && $$ RAH/JPR mn AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN 536 PM CDT SAT APR 19 2008 .DISCUSSION... LOW PRESSURE CONTINUES TO DRIFT SLOWLY EASTWARD ACROSS THE LOWER GREAT LAKES. A FEW SHOWERS HAVE DEVELOPED THIS AFTERNOON ACROSS THE WI CWA ALONG A TROF AXIS. HELPING MATTERS IS STRONG HEATING THAT HAS DEVELOPED TO THE EAST AND SOUTH OF KEAU WITH SOME CLEARING. THERMAL GRADIENT ACROSS THE WESTERN HALF OF WI ABOUT 20 DEGREES ATTM. RUC BEST LI INTO THE EVENING AROUND ZERO SO WILL MENTION A FEW SHOWERS AND ISOLATED THUNDER THROUGH THE EVENING. NEXT CONCERN IS FOG POTENTIAL OVERNIGHT. BELIEF IS THAT THE LOW LEVEL FLOW WILL BECOME MORE EASTERLY OVERNIGHT DRAGGING SOME OF THE LOW CLOUDS INTO THE WESTERN CWA WHILE MAINTAINING A GOOD DEAL OF CLOUDINESS ELSEWHERE. DUE TO THE RAINS OVER WI AND SOUTH CENTRAL AREAS OF MN...AREAS OF FOG SHOULD OCCUR AGAIN TONIGHT. HOWEVER..IT COULD BECOME DENSE IF THE LOW CLOUDS WOULD DIMINISH DURING THE NIGHT. THIS LEADS INTO SUNDAY ON HOW HIGH AFTERNOON TEMPERATURES WILL GET IF PARTLY TO MOSTLY CLOUDY SKIES PREVAIL. NAM CU RULE IS QUITE NEGATIVE OVER EASTERN MN AND WEST CENTRAL WI...SO CUT BACK A LITTLE ON THE HIGH TEMPERATURES OVER THE EASTERN HALF OF THE CWA. THINGS REMAIN PRETTY MUCH ON TRACK WITH LOW PRESSURE AND A COLD FRONT APPROACHING WESTERN MN SUNDAY NIGHT AND THEN MOVING TO NEAR THE MN/WI BORDER BY MONDAY NIGHT. MAIN CHANGES TODAY WERE TO TIGHTEN UP ON THE POPS AND KEEP THEM CONFINED TO THE FAR WEST SUNDAY NIGHT WHERE SOME ELEVATED INSTABILITY DEVELOPS AND THEN NOT ALLOW THINGS TO GET TO FAR TO THE EAST TOO FAST ON MONDAY. STILL LOOKS GOOD FOR SHOWERS AND THUNDERSTORMS ALONG THE FRONT...ESPECIALLY EASTERN MN LATE MONDAY AFTERNOON AND EVENING AND THEN SPREADING INTO WI DURING THE NIGHT. THE FRONT BECOMES NEARLY STATIONARY ACROSS WEST CENTRAL WI BY TUESDAY MORNING AS LOW PRESSURE BEGINS TO RIDE NORTHEAST ALONG THE FRONT. PRECIPITATION CHANCES REMAIN HIGH OVER THE EASTERN CWA UNTIL TUESDAY EVENING. CAPE VALUES MODEST ON MONDAY AND LOW LEVEL SHEAR IS DIMINISHING MONDAY AFTERNOON. WHAT IS REALLY INTERESTING IS THE COUPLED JET THAT DEVELOPS ACROSS OUR AREA MONDAY NIGHT AND TUESDAY...GIVING THE EASTERN CWA QUITE A BIT OF DIFFERENTIAL LAYER DIVERGENCE. THIS WILL BE A PERIOD THAT WILL NEED TO BE MONITORED NOT ONLY FOR SEVERE WEATHER BUT HEAVY RAINFALL. A BREAK IN THE RAIN ON WEDNESDAY AS HIGH PRESSURE MOVES BY THEN A MORE VIGOROUS LOW WILL BE MOVING IN FROM THE CENTRAL PLAINS THURSDAY AND FRIDAY WITH SOME PRETTY GOOD APRIL SHOWERS AND THUNDERSTORMS. && .AVIATION.../00Z TAF ISSUANCE/ TAMDAR SOUNDINGS FROM AIRCRAFT IN AND OUT OF MSP STILL REVEALING A SEVERAL THOUSAND FEET THICK LOW LEVEL MOISTURE LAYER. SOUNDINGS OUT OF EAU AIRPORT SHOW LESS DEPTH TO THE MOISTURE AND VISIBLE SATELLITE CHANNEL IS INDEED PORTRAYING WHOLES IN THE CLOUD COVER NEAR EAU. CONDITIONS WILL LIKELY GO SCT THERE AT TIMES THIS EVE. THIS WILL SET THE STAGE FOR FOG NEAR EAU THAT MAY LAST INTO THE POST DAYBREAK HOURS ON SUN. MSP...RNH...AND STC MORE LIKELY TO STAY UNDER MVFR/IFR STRATUS. LOW T/TDS SPREADS WILL LIKELY PRESENT AT LEAST SOME MVFR VISBYS OVERNIGHT. OUT WEST...AXN AND RWF WILL FEEL THE EFFECT OF THE LOW CLOUDS TONIGHT AS THEY BEGIN TO BE CAUGHT IN THE RETURN FLOW AND RETROGRADE WESTWARD. CONDITIONS MORE LIKELY TO STAY MVFR AT THESE SITES. DURING SUNDAY THE CLOUDS SHOULD BE SLOW TO BREAK IN THE MORNING AS LOW LEVEL WIND GRADIENT IS SOMEWHAT LAX. BUT IN THE AFTN A MORE RAPID SCATTERING IS LIKELY. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...NONE. WI...NONE. && $$ RAH/MTF mn AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN 1244 PM CDT SAT APR 19 2008 .UPDATE...FOR 18Z AVIATION DISCUSSION BELOW && .DISCUSSION.../ISSUED 355 AM CDT SAT APR 19 2008/ EARLY MORNING WATER VAPOR IMAGERY SHOWS CUTOFF UPPER LOW CONTINUING TO SPIN OVER THE MID MISSISSIPPI RIVER VALLEY AND DRIFTING EAST. THE TROUGH HAS TAKEN ON A NEGATIVE TILT THROUGH THE EVENING WITH 295 K SFC SHOWING UPGLIDE INTO WEST CENT WI AND EAST CENT MN EARLY THIS MORNING. RADAR CONTINUES TO SHOW BANDS OF LIGHT RAIN ROTATING NORTHWESTWARD. THE BACK EDGE OF THE BAND HAS BEGUN TO DRIFT BACK EASTWARD AFTER A WESTWARD MARCH LATE LAST NIGHT WITH RUC 295 K DATA INDICATING THAT THIS TREND WILL CONTINUE. HAVE KEPT LOW POPS ACROSS EAST CENT MN THROUGH THE MORNING WITH THE LOW CONTINUING TO HAVE INFLUENCE WITH HIGHER CHANCE POPS IN WISCONSIN AS RAIN SHIELD PULLS BACK EAST. DECIDED TO KEEP SLIGHT POPS IN FAR EAST CENT MN...INCLUDING MUCH OF THE TWIN CITIES METRO THIS AFTERNOON WITH MID LEVEL LAPSE RATES STEEPENING AND POTENTIAL FOR SOME BREAKS IN THE CLOUD COVER SUPPORTING SMALL CHANCE FOR SHOWER DEVELOPMENT. KEPT PARTLY TO MOSTLY CLOUD SKIES ACROSS THE MN COUNTIES TODAY WITH LOW LEVEL FLOW CONTINUING TO PUSH CLOUD COVER WESTWARD BUT DRIER AIR WILL BEGIN TO WIN OUT HELPING TO DECREASE THE CLOUD OVERAGE FROM WEST TO EAST ACROSS WEST CENT MN. TEMPERATURES WILL BE VERY DEPENDENT ON BREAKING UP OF CLOUDS. THE WEST AND NORTHWEST SHOULD REACH THE LOWER 60S WITH THE EAST CENT MN COUNTIES IN THE UPPER 50S TO NEAR 60 WITH MORE ABUNDANT CLOUD COVER...AND WEST CENT WI REACHING THE LOW TO MID 50S WITH CONTINUED CLOUDS AND SHOWERS. HIGH PRESSURE BUILDS IN TONIGHT WITH WEAK SFC FLOW TAKING HOLD. ADDED FOG FOR MUCH OF THE EASTERN CWA GIVEN THE RAINFALL AND DECREASING WINDS. INTERESTING WEATHER CONTINUES INTO EARLY NEXT WEEK AS CUTOFF UPPER LOW SPINS EASTWARD ACROSS THE APPALACHIANS AND BROAD CLOSED OFF UPPER LOW CURRENTLY OVER THE WASHINGTON STATE/BRITISH COLUMBIA BORDER TAKES RESIDENCE OVER MUCH OF THE NORTHWEST U.S. AS OMEGA BLOCK SETS UP OVER THE EASTERN PACIFIC. LOCALLY...THIS SETS UP SOUTHERLY UPPER LEVEL FLOW WITH SFC LOW PRESSURE BECOMING ESTABLISHED TO THE WEST OVER THE HIGH PLAINS UNDER UPPER HEIGHT FALLS. THIS WILL ALLOW SOUTHERLY SFC FLOW TO TAKE OVER INTO SUNDAY AND CONTINUE THROUGH MONDAY WITH MID LEVEL WARMTH BUILDING OVERHEAD AS EVIDENCED BY +10 TO +12 H85 TEMPS. THIS WILL ALLOW A NICE WARM UP INTO THE UPPER 60S TO AROUND 70 SUNDAY AND MONDAY. A FRONTAL BOUNDARY WILL APPROACH MONDAY WITH ADDITIONAL WARMING THROUGH COMPRESSIONAL HEATING POSSIBLE SO WILL NEED TO WATCH TEMPS MONDAY. WITH THE UPPER LOW STILL HANGING BACK WELL TO THE WEST MONDAY THE FRONT WILL TAKE ITS TIME CROSSING THE AREA. THE UPPER LOW THEN BEGINS TO KICK NORTHEAST INTO CENTRAL CANADA AS A LOW UNDERCUTS THE PACIFIC OMEGA RIDGE ALLOWING EVOLUTION INTO A REX PATTERN TO TAKE PLACE. THE LOCAL RESULT IS SFC CYCLOGENESIS OVER THE UPPER MISSISSIPPI RIVER VALLEY BY EARLY TUESDAY SENDING STRENGTHENING SFC LOW NORTHWARD ACROSS EASTERN MN TUESDAY MORNING. SHOWERS AND THUNDERSTORMS ARE EXPECT TO DEVELOP AS EARLY AS MONDAY MORNING ACROSS WEST-CENTRAL MINNESOTA AS FRONT APPROACHES WITH BETTER CHANCES ARRIVING MONDAY EVENING AS SFC LOW INTENSIFIES. NAM-WRF IS SHOWING STRONGER INSTABILITY AT THIS POINT WITH CAPE VALUES EXCEEDING 1000 J/KG AND BEST COLUMN LI/S OF -4 WITH STRONGER MOISTURE ADVECTION THAN THE GFS. PWAT INCREASES OF MORE THAN A QUARTER INCH IN 6 HOURS ALSO APPEAR MONDAY EVENING. THE EASTWARD PROGRESS OF THE FRONT SLOWS TUESDAY MORNING AS THE SFC LOW MOVES NORTHWARD ALONG IT ALLOWING A LONGER PERIOD OF SHOWERS AND THUNDERSTORMS ACROSS EAST CENT MN AND WEST CENT WI. SFC HIGH PRESSURE SETTLES TO THE WEST INTO WEDNESDAY BUT SEVERAL SHORTWAVES TRAVERSE THE AREA KEEPING A LOW CHANCE FOR ADDITIONAL SHOWERS BUT DRY CONDITIONS LOOK TO FILL IN DURING THE DAY WEDNESDAY WITH HIGH PRESSURE TO THE SOUTH. COOLER AIR WILL ALSO ARRIVE WITH H85 TEMPS BACK BELOW ZERO. BRIEF ZONAL FLOW OF AIR IN THE MID LEVELS KEEPS THINGS QUIET INTO WEDNESDAY NIGHT BUT THERE ARE INDICATIONS OF UPPER FLOW TRYING TO BUCKLE WITH ANOTHER SFC LOW APPROACHING FROM THE WEST. WARM AIR ADVECTION COMMENCES THURSDAY MORNING WITH ENOUGH MOISTURE IN PLACE BY THAT TIME TO SUPPORT PRECIP CHANCES ONCE AGAIN. ..MDB.. && .AVIATION.../18Z TAF ISSUANCE/ LOW CLOUDS CONTINUE TO PLAGUE ALL TAF SITES BUT KAXN THIS AFTERNOON. ALTHOUGH EXPECT KSTC/KRWF TO SEE A FEW BREAKS IN THE CLOUDS THIS AFTERNOON...MVFR CEILINGS WILL REMAIN ENTRENCHED AT KMSP/KRNH/KEAU...WHICH IS SUPPORTED BY THE NAM 925 MB RH PROGS. CEILINGS WILL DEGRADE FURTHER THIS EVENING/TONIGHT...WITH IFR CONDITIONS EXPECTED TO DEVELOP AT ALL SITES AFTER MIDNIGHT. AREAS OF FOG ARE ALSO LIKELY...WITH WIDESPREAD VISIBILITIES BETWEEN 1 AND 3 MPH EXPECTED. CONDITIONS WILL LIKELY NOT BEGIN IMPROVING INTO THE VFR CATEGORY UNTIL AROUND/AFTER 15Z SUNDAY...AS THE WINDS PICK UP ABOVE 10 KNOTS. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...NONE. WI...NONE. && $$ LS/MDB mn AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN 715 AM CDT SAT APR 19 2008 .DISCUSSION... EARLY MORNING WATER VAPOR IMAGERY SHOWS CUTOFF UPPER LOW CONTINUING TO SPIN OVER THE MID MISSISSIPPI RIVER VALLEY AND DRIFTING EAST. THE TROUGH HAS TAKEN ON A NEGATIVE TILT THROUGH THE EVENING WITH 295 K SFC SHOWING UPGLIDE INTO WEST CENT WI AND EAST CENT MN EARLY THIS MORNING. RADAR CONTINUES TO SHOW BANDS OF LIGHT RAIN ROTATING NORTHWESTWARD. THE BACK EDGE OF THE BAND HAS BEGUN TO DRIFT BACK EASTWARD AFTER A WESTWARD MARCH LATE LAST NIGHT WITH RUC 295 K DATA INDICATING THAT THIS TREND WILL CONTINUE. HAVE KEPT LOW POPS ACROSS EAST CENT MN THROUGH THE MORNING WITH THE LOW CONTINUING TO HAVE INFLUENCE WITH HIGHER CHANCE POPS IN WISCONSIN AS RAIN SHIELD PULLS BACK EAST. DECIDED TO KEEP SLIGHT POPS IN FAR EAST CENT MN...INCLUDING MUCH OF THE TWIN CITIES METRO THIS AFTERNOON WITH MID LEVEL LAPSE RATES STEEPENING AND POTENTIAL FOR SOME BREAKS IN THE CLOUD COVER SUPPORTING SMALL CHANCE FOR SHOWER DEVELOPMENT. KEPT PARTLY TO MOSTLY CLOUD SKIES ACROSS THE MN COUNTIES TODAY WITH LOW LEVEL FLOW CONTINUING TO PUSH CLOUD COVER WESTWARD BUT DRIER AIR WILL BEGIN TO WIN OUT HELPING TO DECREASE THE CLOUD OVERAGE FROM WEST TO EAST ACROSS WEST CENT MN. TEMPERATURES WILL BE VERY DEPENDENT ON BREAKING UP OF CLOUDS. THE WEST AND NORTHWEST SHOULD REACH THE LOWER 60S WITH THE EAST CENT MN COUNTIES IN THE UPPER 50S TO NEAR 60 WITH MORE ABUNDANT CLOUD COVER...AND WEST CENT WI REACHING THE LOW TO MID 50S WITH CONTINUED CLOUDS AND SHOWERS. HIGH PRESSURE BUILDS IN TONIGHT WITH WEAK SFC FLOW TAKING HOLD. ADDED FOG FOR MUCH OF THE EASTERN CWA GIVEN THE RAINFALL AND DECREASING WINDS. INTERESTING WEATHER CONTINUES INTO EARLY NEXT WEEK AS CUTOFF UPPER LOW SPINS EASTWARD ACROSS THE APPALACHIANS AND BROAD CLOSED OFF UPPER LOW CURRENTLY OVER THE WASHINGTON STATE/BRITISH COLUMBIA BORDER TAKES RESIDENCE OVER MUCH OF THE NORTHWEST U.S. AS OMEGA BLOCK SETS UP OVER THE EASTERN PACIFIC. LOCALLY...THIS SETS UP SOUTHERLY UPPER LEVEL FLOW WITH SFC LOW PRESSURE BECOMING ESTABLISHED TO THE WEST OVER THE HIGH PLAINS UNDER UPPER HEIGHT FALLS. THIS WILL ALLOW SOUTHERLY SFC FLOW TO TAKE OVER INTO SUNDAY AND CONTINUE THROUGH MONDAY WITH MID LEVEL WARMTH BUILDING OVERHEAD AS EVIDENCED BY +10 TO +12 H85 TEMPS. THIS WILL ALLOW A NICE WARM UP INTO THE UPPER 60S TO AROUND 70 SUNDAY AND MONDAY. A FRONTAL BOUNDARY WILL APPROACH MONDAY WITH ADDITIONAL WARMING THROUGH COMPRESSIONAL HEATING POSSIBLE SO WILL NEED TO WATCH TEMPS MONDAY. WITH THE UPPER LOW STILL HANGING BACK WELL TO THE WEST MONDAY THE FRONT WILL TAKE ITS TIME CROSSING THE AREA. THE UPPER LOW THEN BEGINS TO KICK NORTHEAST INTO CENTRAL CANADA AS A LOW UNDERCUTS THE PACIFIC OMEGA RIDGE ALLOWING EVOLUTION INTO A REX PATTERN TO TAKE PLACE. THE LOCAL RESULT IS SFC CYCLOGENESIS OVER THE UPPER MISSISSIPPI RIVER VALLEY BY EARLY TUESDAY SENDING STRENGTHENING SFC LOW NORTHWARD ACROSS EASTERN MN TUESDAY MORNING. SHOWERS AND THUNDERSTORMS ARE EXPECT TO DEVELOP AS EARLY AS MONDAY MORNING ACROSS WEST-CENTRAL MINNESOTA AS FRONT APPROACHES WITH BETTER CHANCES ARRIVING MONDAY EVENING AS SFC LOW INTENSIFIES. NAM-WRF IS SHOWING STRONGER INSTABILITY AT THIS POINT WITH CAPE VALUES EXCEEDING 1000 J/KG AND BEST COLUMN LI/S OF -4 WITH STRONGER MOISTURE ADVECTION THAN THE GFS. PWAT INCREASES OF MORE THAN A QUARTER INCH IN 6 HOURS ALSO APPEAR MONDAY EVENING. THE EASTWARD PROGRESS OF THE FRONT SLOWS TUESDAY MORNING AS THE SFC LOW MOVES NORTHWARD ALONG IT ALLOWING A LONGER PERIOD OF SHOWERS AND THUNDERSTORMS ACROSS EAST CENT MN AND WEST CENT WI. SFC HIGH PRESSURE SETTLES TO THE WEST INTO WEDNESDAY BUT SEVERAL SHORTWAVES TRAVERSE THE AREA KEEPING A LOW CHANCE FOR ADDITIONAL SHOWERS BUT DRY CONDITIONS LOOK TO FILL IN DURING THE DAY WEDNESDAY WITH HIGH PRESSURE TO THE SOUTH. COOLER AIR WILL ALSO ARRIVE WITH H85 TEMPS BACK BELOW ZERO. BRIEF ZONAL FLOW OF AIR IN THE MID LEVELS KEEPS THINGS QUIET INTO WEDNESDAY NIGHT BUT THERE ARE INDICATIONS OF UPPER FLOW TRYING TO BUCKLE WITH ANOTHER SFC LOW APPROACHING FROM THE WEST. WARM AIR ADVECTION COMMENCES THURSDAY MORNING WITH ENOUGH MOISTURE IN PLACE BY THAT TIME TO SUPPORT PRECIP CHANCES ONCE AGAIN. ..MDB.. && .AVIATION.../12Z TAF ISSUANCE/ THE TAF ISSUANCE FOR THIS PERIOD REFLECTS A 50H CUTOFF LOW CROSSING THE CENTRAL MISSISSIPPI VALLEY WITH DEFORMATION RELATED PRECIPITATION ACROSS SOUTHERN MN INTO WESTERN WISCONSIN. ACCORDINGLY...KMSP...KEAU AND KRNH START OUT WITH IFR CONDITIONS IN LOW CEILINGS. THE THREAT FOR PRECIPITATION DROPS OFF AT KMSP AROUND 14Z BUT LINGERS THROUGH MORNING AT KEAU. WITH A NARROW RIDGE OF HIGH PRESSURE FORECAST ACROSS MN TNGT...A GOOD PART OF THE AREA APPEARS VULNERABLE FOR SOME FOG. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...NONE. WI...NONE. && $$ mn AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE KANSAS CITY/PLEASANT HILL MO 418 AM CDT SUN APR 20 2008 .DISCUSSION... SURFACE HIGH PRESSURE CONTINUES TO SLIDE SLOWLY EAST ACROSS CENTRAL PORTIONS OF MISSOURI EARLY THIS MORNING. PESKY STRATUS CLOUDS PERSIST ACROSS NORTH CENTRAL AND NORTHEAST MISSOURI STILL THIS MORNING...BUT SHOULD BE EXITING BY AFTERNOON ALONG WITH THE H8 RIDGE AXIS. THERE HAVE BEEN SOME VARIABLE LOWER VISIBILITIES WITH FOG THIS MORNING...MAINLY IN PROXIMITY TO THE SURFACE RIDGE AXIS WHERE WINDS ARE CALM AND WHERE THE LOW CLOUDS HAVE CLEARED. CONTINUED TO MENTION SOME PATCHY FOG IN THE FORECAST FOR EARLY MORNING...WITH IMPROVEMENT EXPECTED SHORTLY AFTER SUNRISE. TEMPERATURES TODAY WILL WARM RATHER SIGNIFICANTLY...EVEN WITH SOME HIGHER LEVEL CLOUDS SPREADING OVER THE REGION. MIDDLE TO UPPER 70S ARE EXPECTED FOR DAYTIME HIGH TEMPERATURES TODAY...WITH INCREASING SOUTHERLY WINDS DEVELOPING AHEAD OF THE NEXT LOW PRESSURE SYSTEM. THE SOUTHERLY WINDS WILL ALSO START THE RETURN OF INCREASING MOISTURE TO THE REGION THROUGH TOMORROW. THE MOISTURE RETURN WILL SET THE STAGE FOR INCREASED CLOUDS MONDAY...AND EVENTUAL PRECIPITATION CHANCES. KEPT SLIGHT CHANCES FOR SOME POSSIBLE SCATTERED SHOWER AND THUNDERSTORM DEVELOPMENT DURING THE AFTERNOON MONDAY. INSTABILITY WILL BE IN PLACE ALONG WITH WARM ADVECTION/ISENTROPIC LIFT...BUT THE LIMITING FACTOR COULD BE THE FORECAST STRONG CAP. AS A SECONDARY SHORTWAVE TROUGH ROTATES ACROSS THE PLAINS ON THE SOUTHEAST SIDE OF THE SOUTH CENTRAL CANADA UPPER LOW...A SURFACE COLD FRONT WILL BE PUSHED INTO THE FORECAST AREA. THE TIMING OF THE FRONT DIFFERS AMONGST THE MODEL SOLUTIONS. AM EXPECTING THE NORTHERN PORTION OF THE COLD FRONT TO BE PUSHED EAST FASTER ACROSS THE NORTHERN PLAINS WITH THE INITIAL SHORTWAVE...WITH THE SOUTHERN PORTION OF THE FRONT STALLING UNTIL THE SECONDARY SHORTWAVE PUSHES IT EAST. THIS WOULD DELAY THE ARRIVAL OF THE COLD FRONT TO NORTHWEST MISSOURI UNTIL LATE MONDAY NIGHT...WHICH IS WHAT THE GFS SOLUTION HAS BEEN SHOWING. THE CONVERGENCE ALONG THE FRONT MAY BE WHAT IS NEEDED FOR CONVECTION TO BREAK THROUGH THE CAP MONDAY NIGHT INTO EARLY TUESDAY...WHERE THE GRIDDED FORECAST DISPLAYS INCREASED PRECIPITATION CHANCES. STILL CANNOT RULE OUT SOME STRONGER STORMS OVERNIGHT MONDAY INTO EARLY TUESDAY. THE COLD FRONT WILL CONTINUE TO PUSH SOUTHEAST ACROSS THE FORECAST AREA DURING THE DAY TUESDAY....EVENTUALLY PUSHING INTO ARKANSAS. THE FRONT WILL THEN RETURN NORTH AS A WARM FRONT TOWARD THURSDAY...ALONG WITH ANOTHER CHANCE FOR SHOWERS AND STORMS. STOFLET && .AVIATION... FOR THE 06Z TAFS...NAM AND RUC SOUNDINGS DEPICTING THE POTENTIAL FOR FOG DEVELOPMENT BEGINNING IN THE 08-09 UTC TIMEFRAME AT STJ AND PERSISTING THROUGH 13 UTC. BASED ON CLIMATOLOGY...THE DENSEST FOG LIKELY WILL NOT OCCUR UNTIL AROUND SUNRISE...THUS CONTINUED PREVIOUS TAF FORECAST TREND OF INTRODUCING TEMPO GROUP IN THE 10-13 TIMEFRAME. ANY FOG THAT DEVELOPS AT STJ WILL DISSIPATE BY 14-15 UTC DUE TO MIXING. BY LATE MORNING...PRESSURE GRADIENT TIGHTENS SUFFICIENTLY THUS WIND SPEEDS AT ALL THREE TAF SITES WILL INCREASE AT OR ABOVE 12 KNOTS BY 16 UTC. OTHERWISE...VFR CONDITIONS WILL PREVAIL. 24 && .EAX WATCHES/WARNINGS/ADVISORIES... MO...NONE. KS...NONE. $$ mo AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE KANSAS CITY/PLEASANT HILL MO 1100 PM CDT SAT APR 19 2008 ...UPDATED FOR AVIATION... .UPDATE... STRATUS DECK HAS BEEN SLOW TO MOVE EAST TONIGHT...WITH H8 RIDGE AXIS A GOOD DELINEATOR TO THE WESTERN EDGE OF STRATUS. QUICK PEEK AT LATEST RUC INDICATES H8 RIDGE AXIS WILL EDGE SLOWLY EAST OVERNIGHT AND WILL CLEAR EASTERN EDGE OF CWA BY 12 UTC. GIVEN THIS SCENARIO...INCREASED MINIMUM TEMPETURES A COUPLE DEGREES ACROSS EASTERN CWA DUE TO PERSISTENT CLOUD COVER. ALSO TRIMMED FOG POTENTIAL A LITTLE WHERE SKIES HAVE CLEARED. CIRRUS SHIELD IS ADVECTING RAPIDLY EASTWARD ACROSS KANSAS AND COUPLED WITH SLIGHTLY GREATER LOW LEVEL WINDS WILL DETRACT FROM RADIATIONAL FOG FORMATION. GIVEN TEMPERATURES WILL DROP WITH 2-3 DEGREES OF DEWPOINTS...KEPT MENTION OF PATCHY FOG IN FORECAST...ESPECIALLY ALONG RIVER VALLEYS OF NORTH WEST AND NORTH CENTRAL MISSOURI. .DISCUSSION... UPR LOW HAS FINALLY EXITED STAGE RIGHT THIS AFTN...TAKING WITH IT A RATHER PESKY LOW-LVL CLOUD DECK. THIS CLEARING HAS ALLOWED MANY LOCATIONS TO EXPERIENCE SUNSHINE TODAY...HOWEVER CLEARING MAY BE TOO LATE FOR THOSE LIVING ACROSS THE EASTERN HALF OF THE CWA. OTHERWISE FAIRLY BENIGN WEATHER CAN BE EXPECTED FOR THE NEXT 36-48 HOURS...AS MID-LVL RIDGING MOVES IN FROM THE WEST. FOR TONIGHT...GIVEN THE EXTENSIVE CLOUD COVER OVER THE NE HALF OF THE CWA DEW POINTS HAVE NOT BEEN ABLE TO SCOUR OUT AS IN LOCATIONS FURTHER WEST. THUS WITH SFC RIDGE AXIS SLIDING OVERHEAD OVERNIGHT AND CLEARING SKIES FROM WEST TO EAST...FEEL AREAS OF FOG WILL BE POSSIBLE BY DAYBREAK. PERHAPS THE NICEST DAY OF THE YEAR SO FAR WILL BE ON TAP FOR SUNDAY AS H850 RIDGE AXIS SLIDES EAST AND SFC WINDS QUICKLY VEER TO THE SW. EVEN THOUGH WE MAY NOT BE ABLE TO TAP THE FULL POTENTIAL OF THE +13C TO +15C H850 AIR OVERHEAD...HIGHS WILL BE SOME 10+ DEGREES ABOVE NORMAL OVERALL. GUIDANCE DOES INDICATE A BIT OF MID-UPR LVL CLOUD COVER LIFTING NE BY MID-DAY...AT THIS POINT NOT FEELING THIS WILL HURT TEMPS MUCH. MODELS CONTINUE TO BOUNCE AROUND A BIT ON UPCOMING COOL FRONT ON MON. PREFER THE SLIGHTLY SLOWER GFS/UKMET/CMC SOLN...KEEPING EFFECTIVE FRONT WEST OF THE CWA BY MON AFTN...AND MUCH OF THE AREA CAPPED. THEREFORE HAVE TRIMMED BACK MON AM POPS. BEST SYNOPTIC FORCING DOESN`T ARRIVE UNTIL MON EVE/OVERNIGHT AS DISTURBANCE SWINGS AROUND UPR TROUGH AND SHOULD ERODE EML. QUESTION MARK FOR MONDAY WILL BE SPEED AND VOLUME OF MOISTURE WHICH CAN BE LIFTED NORTHWARD. DECENT MOISTURE TRANSPORT SUNDAY NIGHT WILL QUICKLY BE SHUNTED EAST AS LLJ VEERS RATHER RAPIDLY. DEEPENING ON VOLUME OF MOISTURE SURGE AND ASSOCIATED STRATUS DECK...INSTABILITY/HEATING MAY BE AFFECTED OVER THE CWA. AS FAR AS SVR CHANCES ARE CONCERNED...SHEAR AND INSTABILITY REMAIN THE BIGGEST QUESTIONS...CANNOT RULE OUT SCT STRONG CONVECTION OVERNIGHT MONDAY ESPECIALLY OVER THE NORTHERN CWA. HOWEVER...MADE FEW CHANCES TO CURRENT POPS AND TEMPS AS BOTH SEEM REASONABLE ATTM. DUX MEDIUM RANGE (TUE-SAT) WHILE MODELS SHOW SOME DIFFERENCES IN TIMING THE FRONT THROUGH THE REGION ON TUESDAY...THEY ARE IN AGREEMENT WITH IT GETTING EAST OF THE FORECAST AREA BY TUESDAY EVENING. SO HAVE TAPERED POPS DURING THE DAY TUESDAY WITH FORECAST AREA DRY BY TUESDAY NIGHT. EXPECT HIGH TEMPERATURES TUESDAY TO BE WELL INTO THE 70S AHEAD OF THE FRONT...WITH READINGS REACHING THE MID 60S BEHIND IT. RELATIVELY COOL HIGH PRESSURE MOVING IN BEHIND THE FRONT SHOULD KEEP THE REGION DRY THROUGH WEDNESDAY...WITH TEMPS CLOSER TO NORMAL...MAINLY IN THE MID 60S TO AROUND 70 DEGREES. HOWEVER THE FORECAST FOR THE END OF THE WEEK CONTINUES TO BE SOMEWHAT PROBLEMATIC. MODELS ARE NOT IN GOOD AGREEMENT ON THE EVOLUTION OF THE NEXT SYSTEM. OPERATIONAL GFS IS THE OUTLIER...DEVELOPING A STRONG SURFACE LOW AND ASSOCIATED COLD FRONT OVER THE CENTRAL PLAINS...THEN TAKING THE COLD FRONT QUICKLY EAST THROUGH THE REGION BY THURSDAY NIGHT. THE UPPER LOW IS QUICK ON ITS HEELS...MOVING ACROSS THE REGION ON FRIDAY. HAVE TRENDED MORE TOWARD THE ECMWF SOLUTION...WHICH IS A LITTLE SLOWER AND A LITTLE FARTHER NORTH WITH THE SURFACE AND UPPER LOWS. HAVE TRIMMED BACK POPS A LITTLE WEDNESDAY NIGHT...THINKING DRY EASTERLY WINDS WILL HOLD OFF PRECIP IN EASTERN SECTIONS. IF MOISTURE RETURN IS SHARP ENOUGH AND FAR ENOUGH EAST...THEN MAY GET STORMS ON THE LEADING EDGE ACROSS EASTERN KANSAS AND WESTERN MISSOURI. HOWEVER BASED ON THE LOCATION OF THE EXPECTED DEVELOPING LOW...THINK BEST CHANCE WILL BE WEST OF THE FORECAST AREA WEDNESDAY NIGHT. MOISTURE CONTINUES TO OVERSPREAD THE REGION ON THURSDAY...POSSIBLY BRINGING SCATTERED THUNDERSTORMS. HAVE PRECIP CHANCES CONTINUING THROUGH FRIDAY...WHEN THE ECMWF BRINGS THE COLD FRONT ACROSS THE FORECAST AREA. PROGS SUGGEST THE FRONT MAY HANG UP ACROSS OR JUST SOUTH OF THE FORECAST AREA. POPS AND QPF ARE CURRENTLY NOT VERY HIGH DUE TO THE EXPECTED TIMING CHANGES IN UPCOMING FORECASTS...BUT BOTH WILL INCREASE AS THE FORECAST BECOMES MORE CLEAR. NRR && .AVIATION... FOR THE 06Z TAFS...NAM AND RUC SOUNDINGS DEPICTING THE POTENTIAL FOR DEVELOPMENT BEGINNING IN THE 08-09 UTC TIMEFRAME AT STJ AND PERSISTING THROUGH 13 UTC. BASED ON CLIMATOLOGY...THE DENSEST FOG LIKELY WILL NOT OCCUR UNTIL AROUND SUNRISE...THUS CONTINUED PREVIOUS TAF FORECAST TREND OF INTRODUCING TEMPO GROUP IN THE 10-13 TIMEFRAME. ANY FOG THAT DEVELOPS AT STJ WILL DISSIPATE BY 14-15 UTC DUE TO MIXING. BY LATE MORNING...PRESSURE GRADIENT TIGHTENS SUFFICIENTLY THUS WIND SPEEDS AT ALL THREE TAF SITES WILL INCREASE AT OR ABOVE 12 KNOTS BY 16 UTC. OTHERWISE...VFR CONDITIONS WILL PREVAIL. 24 && .EAX WATCHES/WARNINGS/ADVISORIES... MO...NONE. KS...NONE. $$ mo AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE KANSAS CITY/PLEASANT HILL MO 1035 PM CDT SAT APR 19 2008 .UPDATE... STRATUS DECK HAS BEEN SLOW TO MOVE EAST TONIGHT...WITH H8 RIDGE AXIS A GOOD DELINEATOR TO THE WESTERN EDGE OF STRATUS. QUICK PEEK AT LATEST RUC INDICATES H8 RIDGE AXIS WILL EDGE SLOWLY EAST OVERNIGHT AND WILL CLEAR EASTERN EDGE OF CWA BY 12 UTC. GIVEN THIS SCENARIO...INCREASED MINIMUM TEMPETURES A COUPLE DEGREES ACROSS EASTERN CWA DUE TO PERSISTENT CLOUD COVER. ALSO TRIMMED FOG POTENTIAL A LITTLE WHERE SKIES HAVE CLEARED. CIRRUS SHIELD IS ADVECTING RAPIDLY EASTWARD ACROSS KANSAS AND COUPLED WITH SLIGHTLY GREATER LOW LEVEL WINDS WILL DETRACT FROM RADIATIONAL FOG FORMATION. GIVEN TEMPERATURES WILL DROP WITH 2-3 DEGREES OF DEWPOINTS...KEPT MENTION OF PATCHY FOG IN FORECAST...ESPECIALLY ALONG RIVER VALLEYS OF NORTH WEST AND NORTH CENTRAL MISSOURI. .DISCUSSION... UPR LOW HAS FINALLY EXITED STAGE RIGHT THIS AFTN...TAKING WITH IT A RATHER PESKY LOW-LVL CLOUD DECK. THIS CLEARING HAS ALLOWED MANY LOCATIONS TO EXPERIENCE SUNSHINE TODAY...HOWEVER CLEARING MAY BE TOO LATE FOR THOSE LIVING ACROSS THE EASTERN HALF OF THE CWA. OTHERWISE FAIRLY BENIGN WEATHER CAN BE EXPECTED FOR THE NEXT 36-48 HOURS...AS MID-LVL RIDGING MOVES IN FROM THE WEST. FOR TONIGHT...GIVEN THE EXTENSIVE CLOUD COVER OVER THE NE HALF OF THE CWA DEW POINTS HAVE NOT BEEN ABLE TO SCOUR OUT AS IN LOCATIONS FURTHER WEST. THUS WITH SFC RIDGE AXIS SLIDING OVERHEAD OVERNIGHT AND CLEARING SKIES FROM WEST TO EAST...FEEL AREAS OF FOG WILL BE POSSIBLE BY DAYBREAK. PERHAPS THE NICEST DAY OF THE YEAR SO FAR WILL BE ON TAP FOR SUNDAY AS H850 RIDGE AXIS SLIDES EAST AND SFC WINDS QUICKLY VEER TO THE SW. EVEN THOUGH WE MAY NOT BE ABLE TO TAP THE FULL POTENTIAL OF THE +13C TO +15C H850 AIR OVERHEAD...HIGHS WILL BE SOME 10+ DEGREES ABOVE NORMAL OVERALL. GUIDANCE DOES INDICATE A BIT OF MID-UPR LVL CLOUD COVER LIFTING NE BY MID-DAY...AT THIS POINT NOT FEELING THIS WILL HURT TEMPS MUCH. MODELS CONTINUE TO BOUNCE AROUND A BIT ON UPCOMING COOL FRONT ON MON. PREFER THE SLIGHTLY SLOWER GFS/UKMET/CMC SOLN...KEEPING EFFECTIVE FRONT WEST OF THE CWA BY MON AFTN...AND MUCH OF THE AREA CAPPED. THEREFORE HAVE TRIMMED BACK MON AM POPS. BEST SYNOPTIC FORCING DOESN`T ARRIVE UNTIL MON EVE/OVERNIGHT AS DISTURBANCE SWINGS AROUND UPR TROUGH AND SHOULD ERODE EML. QUESTION MARK FOR MONDAY WILL BE SPEED AND VOLUME OF MOISTURE WHICH CAN BE LIFTED NORTHWARD. DECENT MOISTURE TRANSPORT SUNDAY NIGHT WILL QUICKLY BE SHUNTED EAST AS LLJ VEERS RATHER RAPIDLY. DEEPENING ON VOLUME OF MOISTURE SURGE AND ASSOCIATED STRATUS DECK...INSTABILITY/HEATING MAY BE AFFECTED OVER THE CWA. AS FAR AS SVR CHANCES ARE CONCERNED...SHEAR AND INSTABILITY REMAIN THE BIGGEST QUESTIONS...CANNOT RULE OUT SCT STRONG CONVECTION OVERNIGHT MONDAY ESPECIALLY OVER THE NORTHERN CWA. HOWEVER...MADE FEW CHANCES TO CURRENT POPS AND TEMPS AS BOTH SEEM REASONABLE ATTM. DUX MEDIUM RANGE (TUE-SAT) WHILE MODELS SHOW SOME DIFFERENCES IN TIMING THE FRONT THROUGH THE REGION ON TUESDAY...THEY ARE IN AGREEMENT WITH IT GETTING EAST OF THE FORECAST AREA BY TUESDAY EVENING. SO HAVE TAPERED POPS DURING THE DAY TUESDAY WITH FORECAST AREA DRY BY TUESDAY NIGHT. EXPECT HIGH TEMPERATURES TUESDAY TO BE WELL INTO THE 70S AHEAD OF THE FRONT...WITH READINGS REACHING THE MID 60S BEHIND IT. RELATIVELY COOL HIGH PRESSURE MOVING IN BEHIND THE FRONT SHOULD KEEP THE REGION DRY THROUGH WEDNESDAY...WITH TEMPS CLOSER TO NORMAL...MAINLY IN THE MID 60S TO AROUND 70 DEGREES. HOWEVER THE FORECAST FOR THE END OF THE WEEK CONTINUES TO BE SOMEWHAT PROBLEMATIC. MODELS ARE NOT IN GOOD AGREEMENT ON THE EVOLUTION OF THE NEXT SYSTEM. OPERATIONAL GFS IS THE OUTLIER...DEVELOPING A STRONG SURFACE LOW AND ASSOCIATED COLD FRONT OVER THE CENTRAL PLAINS...THEN TAKING THE COLD FRONT QUICKLY EAST THROUGH THE REGION BY THURSDAY NIGHT. THE UPPER LOW IS QUICK ON ITS HEELS...MOVING ACROSS THE REGION ON FRIDAY. HAVE TRENDED MORE TOWARD THE ECMWF SOLUTION...WHICH IS A LITTLE SLOWER AND A LITTLE FARTHER NORTH WITH THE SURFACE AND UPPER LOWS. HAVE TRIMMED BACK POPS A LITTLE WEDNESDAY NIGHT...THINKING DRY EASTERLY WINDS WILL HOLD OFF PRECIP IN EASTERN SECTIONS. IF MOISTURE RETURN IS SHARP ENOUGH AND FAR ENOUGH EAST...THEN MAY GET STORMS ON THE LEADING EDGE ACROSS EASTERN KANSAS AND WESTERN MISSOURI. HOWEVER BASED ON THE LOCATION OF THE EXPECTED DEVELOPING LOW...THINK BEST CHANCE WILL BE WEST OF THE FORECAST AREA WEDNESDAY NIGHT. MOISTURE CONTINUES TO OVERSPREAD THE REGION ON THURSDAY...POSSIBLY BRINGING SCATTERED THUNDERSTORMS. HAVE PRECIP CHANCES CONTINUING THROUGH FRIDAY...WHEN THE ECMWF BRINGS THE COLD FRONT ACROSS THE FORECAST AREA. PROGS SUGGEST THE FRONT MAY HANG UP ACROSS OR JUST SOUTH OF THE FORECAST AREA. POPS AND QPF ARE CURRENTLY NOT VERY HIGH DUE TO THE EXPECTED TIMING CHANGES IN UPCOMING FORECASTS...BUT BOTH WILL INCREASE AS THE FORECAST BECOMES MORE CLEAR. NRR && .AVIATION... FOR THE 18Z TAFS...MVFR DECK NOW RAPIDLY DISSIPATING ACROSS THE TERMINAL LOCATIONS EARLY THIS AFTN. CLOUD DECK WILL CONTINUE TO LIFT INTO VFR CATEGORY WITHIN THE NEXT HOUR. SFC RIDGE WILL SLIDE ACROSS THE TERMINAL SITES THIS EVENING...WITH VARIABLE WINDS EXPECTED. WINDS SHOULD QUICKLY PICK UP SUN MORNING AS LOW-LVL FLOW VEERS TO THE SW. SOUNDINGS INDICATE THE POTENTIAL FOR A BIT OF LIGHT BRIEF FOG DEVELOPMENT IN STJ...AS A RESULT HAVE INTRODUCED A TEMPO GROUP FROM 10-13Z DUX && .EAX WATCHES/WARNINGS/ADVISORIES... MO...NONE. KS...NONE. $$ mo AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE OMAHA/VALLEY NE 943 PM CDT SAT APR 19 2008 .DISCUSSION... HAVE UPDATED FOR A COUPLE OF CHANGES THIS EVENING. SFC RIDGE AXIS AT 02Z WAS ALREADY LOCATED IN CTLR IA...WITH SELY WINDS BECOME ESTABLISHED ACROSS THE CWA. THINK THE WINDS WILL BE ENOUGH TO KEEP MENTIONABLE FOG FROM FORMING...ESPECIALLY IF DRIER DEWPOINTS CONTINUE TO PUSH SEWD OUT OF SD/CTRL NEB. AS A RESULT...HAVE PULLED FOG MENTION FOR THE LATE OVERNIGHT/EARLY MORNING HOURS. HAVE ALSO UPDATED SKY GRIDS FOR CURRENT TRENDS...AS CWA HAS BEEN CLEAR FOR SEVERAL HRS. WILL SEE CI WORK SLOWLY NWD OUT OF KS INTO THE SWRN CWA THROUGH THE OVERNIGHT HOURS...WITH ERN CWA LIKELY TO STAY CLEAR THROUGH THE NIGHT. KEPT GOING MIN TEMPS WITH BALANCE BETWEEN DRIER AIR/CLEAR SKIES AND INCREASING WINDS PREVENTING A FULL DROP-OFF OF TEMPS. && .PREV DISCUSSION... /ISSUED 215 PM CDT SAT APR 19 2008/ DISCUSSION... SHORT TERM CONCERNS WILL BE TEMPS AND FOG POTENTIAL...WINDS SUNDAY...THEN FRONTAL PASSAGE MONDAY/ PRECIP POTENTIAL WITH THE FRONT AND BEHIND THE FRONT MONDAY THROUGH TUESDAY MORNING. STORM SYSTEM HEADING INTO THE OHIO RIVER VALLEY FINALLY PULLING THE CLD SHIELD EAST OF THE FCST AREA. SFC HIGH PRES OVER THE MO VALLEY WILL YIELD LIGHT WINDS AND CLEAR SKIES TONIGHT. FOG...CONTINUED TO MENTION FOG ALONG THE MO RIVER AND EAST INTO WRN IA WITH 1-3 DEG SFC DEWPOINT DEPRESSIONS. HOW FAR TO BRING FOG WEST IS THE QUESTION WITH LOW LEVEL WINDS BEGINNING TO STRENGTHEN BY MORNING. NEXT TO THE AREAS OF FOG ALONG THE MO RIVER...INCLUDED A STRIPE OF PATCHY FOG TO NR THE THE H85 RIDGE LINE...WITH LNK BEING ON THE WRN EXTENT OF THE FOG. LOWS IN THE 40S STILL LOOK REASONABLE TONIGHT. WINDS...THE NAM AND TO A LESSER EXTENT...THE GFS HAS THE 40-50KT LOW LEVEL JET OVER CNTRL NEBRASKA SHIFTING INTO EASTERN NEBRASKA DURING THE MORNING AND WRN IA DURING THE AFTERNOON. THE OVERNIGHT SHIFT WILL NEED TO CONSIDER WIND ADVISORY. PER BUFKIT FCST SOUNDINGS NAM FCSTS WIND ADVISORY POTENTIAL AT OFK/FBY AROUND NOON...AT LNK EARLY IN THE AFTERNOOON...AND AT OMA MID AFTERNOON AND INTO SW IA BY EVE. CURRENT FCST IS CLOSE OR AT WIND ADVISORY FOR SUNDAY...DECREASING AFTER EARLY EVENING...BUT STILL WINDY/BREEZY OVERNIGHT. PRECIP POTENTIAL MONDAY THROUGH EARLY TUESDAY...THE SFC FNT WILL BE MOVING THROUGH THE FCST AREA MONDAY. WITH DYNAMICS NOT REAL IMPRESSIVE...HAVE A SLIGHT CHANCE FOR -TSRA LATE SUNDAY NIGHT...THEN A SLIGHT CHC DURING THE MORNING. WITH A SHORTWAVE TROF APPROACHING IN THE FLOW POST-FRONTAL MONDAY AFTERNOON...KEPT A SLIGHT CHC/CHC FOR SHOWERS/-TSRA. CURRENTLY HAVE HIGHEST POPS MONDAY NIGHT. WITH LINGERING ELEVATED INSTABILITY...LEFT THUNDER MENTION IN. SHORTWAVE IS MOVING EAST OF THE AREA TUESDAY...THUS LOWERED POPS IN THE MORNING AND DROPPED THEM IN THE AFTERNOON. HIGHS IN THE UPR 70S SUNDAY...THEN 60S/70S MONDAY AND TUESDAY. THE EXTENDED TUESDAY NIGHT STARTS OUT WITH THE SFC FRONT S OF THE FCST AREA AND HIGH PRES BUILDING IN. THE NEXT MID TROPOSPHERIC TROF IS OVR THE NW U.S. AND THE ECMWF/GFS SHOW A WEAK WAVE LIFTING ACRS THE WRN PLAINS...MEANWHILE A SFC WRMFT IS DEVELOPING OUT WEST. AM COUNTING OF THIS FEATURE TO BE FAR ENOUGH WEST...TO NOT INCLUDE PRECIP WED. WEDNESDAY NIGHT...HOWEVER...THE SFC LOW FM CO TO WY MOVES INTO WRN NEB AND WRN KS AND THE LOW LEVEL JET INCREASES AND VEERS WITH PRECIP EXPANDING INTO THE PLAINS. AS WE GET INTO THU...THERE ARE A VARIETY OF SOLUTIONS AND TIMING. THE CANADIAN LIFTS THE SFC LOW NORTH TOWARD THE SD/ND BORDER...THE ECMWF TAKES IT TO ERN SD...AND THE GFS TAKES IT TO NW IA. HPC IS USING A ECWMF/ENSEMBLE MEAN APPROACH TO THE EXTENDED. LOOKS LIKE A CHC FOR TSRA THU AND THU NIGHT. HELD ON TO SOME POPS FRIDAY DEPENDING ON THE SPEED/AMPLITUDE OF THE SYSTEM. HIGHS IN THE 60S AND 70S IN THE EXTENDED...EXCEPT SOME 50S FOR FRIDAY. AVIATION... TAF SITES KOMA...KLNK AND KOFK...THRU 20/18Z. MAIN FORECAST ISSUES TONIGHT REVOLVE AROUND POTENTIAL FOG DEVELOPMENT ACROSS EXTREME EASTERN NEBRASKA AND WESTERN IOWA. SURFACE DEWPOINT DEPRESSIONS ARE PROGGED TO FALL TO 1 TO 2 DEGREES WITH LIGHT SOUTHEAST WINDS. RUC WAS MOST AGGRESSIVE WITH FOG DEVELOPMENT...WHICH WAS GENERALLY USED FOR THE FORECAST. ADDED SOME FOG AT KLNK/KOMA BY 09Z/10Z...WITH POTENTIAL TO GET DOWN TO 1/2SM AT KOMA AND 1SM AT KLNK FROM 11Z-13Z...BUT THEN QUICKLY BACK TO P6SM BY 14Z. INCREASING SOUTHEASTERLY SURFACE WINDS SUNDAY MORNING WERE ALSO CONSIDERED...WITH SPEEDS APPROACHING 20KTS SUSTAINED BY 16Z...AND LIKELY HIGHER BY 18Z AND BEYOND ESPECIALLY AT KOFK. && .OAX WATCHES/WARNINGS/ADVISORIES... NE...NONE. IA...NONE. && $$ MAYES ne AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE OMAHA/VALLEY NE 215 PM CDT SAT APR 19 2008 .DISCUSSION... SHORT TERM CONCERNS WILL BE TEMPS AND FOG POTENTIAL...WINDS SUNDAY...THEN FRONTAL PASSAGE MONDAY/ PRECIP POTENTIAL WITH THE FRONT AND BEHIND THE FRONT MONDAY THROUGH TUESDAY MORNING. STORM SYSTEM HEADING INTO THE OHIO RIVER VALLEY FINALLY PULLING THE CLD SHIELD EAST OF THE FCST AREA. SFC HIGH PRES OVER THE MO VALLEY WILL YIELD LIGHT WINDS AND CLEAR SKIES TONIGHT. FOG...CONTINUED TO MENTION FOG ALONG THE MO RIVER AND EAST INTO WRN IA WITH 1-3 DEG SFC DEWPOINT DEPRESSIONS. HOW FAR TO BRING FOG WEST IS THE QUESTION WITH LOW LEVEL WINDS BEGINNING TO STRENGTHEN BY MORNING. NEXT TO THE AREAS OF FOG ALONG THE MO RIVER...INCLUDED A STRIPE OF PATCHY FOG TO NR THE THE H85 RIDGE LINE...WITH LNK BEING ON THE WRN EXTENT OF THE FOG. LOWS IN THE 40S STILL LOOK REASONABLE TONIGHT. WINDS...THE NAM AND TO A LESSER EXTENT...THE GFS HAS THE 40-50KT LOW LEVEL JET OVER CNTRL NEBRASKA SHIFTING INTO EASTERN NEBRASKA DURING THE MORNING AND WRN IA DURING THE AFTERNOON. THE OVERNIGHT SHIFT WILL NEED TO CONSIDER WIND ADVISORY. PER BUFKIT FCST SOUNDINGS NAM FCSTS WIND ADVISORY POTENTIAL AT OFK/FBY AROUND NOON...AT LNK EARLY IN THE AFTERNOOON...AND AT OMA MID AFTERNOON AND INTO SW IA BY EVE. CURRENT FCST IS CLOSE OR AT WIND ADVISORY FOR SUNDAY...DECREASING AFTER EARLY EVENING...BUT STILL WINDY/BREEZY OVERNIGHT. PRECIP POTENTIAL MONDAY THROUGH EARLY TUESDAY...THE SFC FNT WILL BE MOVING THROUGH THE FCST AREA MONDAY. WITH DYNAMICS NOT REAL IMPRESSIVE...HAVE A SLIGHT CHANCE FOR -TSRA LATE SUNDAY NIGHT...THEN A SLIGHT CHC DURING THE MORNING. WITH A SHORTWAVE TROF APPROACHING IN THE FLOW POST-FRONTAL MONDAY AFTERNOON...KEPT A SLIGHT CHC/CHC FOR SHOWERS/-TSRA. CURRENTLY HAVE HIGHEST POPS MONDAY NIGHT. WITH LINGERING ELEVATED INSTABILITY...LEFT THUNDER MENTION IN. SHORTWAVE IS MOVING EAST OF THE AREA TUESDAY...THUS LOWERED POPS IN THE MORNING AND DROPPED THEM IN THE AFTERNOON. HIGHS IN THE UPR 70S SUNDAY...THEN 60S/70S MONDAY AND TUESDAY. THE EXTENDED TUESDAY NIGHT STARTS OUT WITH THE SFC FRONT S OF THE FCST AREA AND HIGH PRES BUILDING IN. THE NEXT MID TROPOSPHERIC TROF IS OVR THE NW U.S. AND THE ECMWF/GFS SHOW A WEAK WAVE LIFTING ACRS THE WRN PLAINS...MEANWHILE A SFC WRMFT IS DEVELOPING OUT WEST. AM COUNTING OF THIS FEATURE TO BE FAR ENOUGH WEST...TO NOT INCLUDE PRECIP WED. WEDNESDAY NIGHT...HOWEVER...THE SFC LOW FM CO TO WY MOVES INTO WRN NEB AND WRN KS AND THE LOW LEVEL JET INCREASES AND VEERS WITH PRECIP EXPANDING INTO THE PLAINS. AS WE GET INTO THU...THERE ARE A VARIETY OF SOLUTIONS AND TIMING. THE CANADIAN LIFTS THE SFC LOW NORTH TOWARD THE SD/ND BORDER...THE ECMWF TAKES IT TO ERN SD...AND THE GFS TAKES IT TO NW IA. HPC IS USING A ECWMF/ENSEMBLE MEAN APPROACH TO THE EXTENDED. LOOKS LIKE A CHC FOR TSRA THU AND THU NIGHT. HELD ON TO SOME POPS FRIDAY DEPENDING ON THE SPEED/AMPLITUDE OF THE SYSTEM. HIGHS IN THE 60S AND 70S IN THE EXTENDED...EXCEPT SOME 50S FOR FRIDAY. && .AVIATION... TAF SITES KOMA...KLNK AND KOFK...THRU 20/18Z. MAIN FORECAST ISSUES TONIGHT REVOLVE AROUND POTENTIAL FOG DEVELOPMENT ACROSS EXTREME EASTERN NEBRASKA AND WESTERN IOWA. SURFACE DEWPOINT DEPRESSIONS ARE PROGGED TO FALL TO 1 TO 2 DEGREES WITH LIGHT SOUTHEAST WINDS. RUC WAS MOST AGGRESSIVE WITH FOG DEVELOPMENT...WHICH WAS GENERALLY USED FOR THE FORECAST. ADDED SOME FOG AT KLNK/KOMA BY 09Z/10Z...WITH POTENTIAL TO GET DOWN TO 1/2SM AT KOMA AND 1SM AT KLNK FROM 11Z-13Z...BUT THEN QUICKLY BACK TO P6SM BY 14Z. INCREASING SOUTHEASTERLY SURFACE WINDS SUNDAY MORNING WERE ALSO CONSIDERED...WITH SPEEDS APPROACHING 20KTS SUSTAINED BY 16Z...AND LIKELY HIGHER BY 18Z AND BEYOND ESPECIALLY AT KOFK. && .OAX WATCHES/WARNINGS/ADVISORIES... NE...NONE. IA...NONE. && $$ ZAPOTOCNY/DEWALD ne AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BISMARCK ND 1043 AM CDT SUN APR 20 2008 .UPDATE... INHERITED GRIDS LOOK TO BE IN LINE WITH CURRENT OBSERVATIONS AND NUMERICAL GUIDANCE. THE MAIN UPDATE WAS TO LOWER HIGH TEMPERATURES SLIGHTLY FOR SUNDAY...SINCE LOW STRATUS HAS SPREAD ACROSS THE WESTERN PART OF THE STATE AND SCATTERED SHOWERS SHOULD SLOW DAYTIME HEATING A BIT. && .PREV DISCUSSION... /ISSUED 418 AM CDT SUN APR 20 2008/ SHORT TERM...TODAY THROUGH TUESDAY NIGHT... MAIN FOCUS TODAY INCLUDES STRONG WINDS THIS MORNING WITH WIND ADVISORY AND RED FLAG WARNING WARRANTED. SEE FIRE WEATHER DISCUSSION FOR RED FLAG DETAILS. THEN FOCUS SHIFTS TO PRECIPITATION CHANCES WITH SURFACE TROUGH/FRONT AND VIGOROUS UPPER LEVEL LOW/TROUGH WITH THUNDERSHOWERS AND RAIN AND SNOW SHOWERS. CURRENTLY...INVERTED TROUGH/COLD FRONT EXTENDED FROM A LOW IN WYOMING NORTHEASTWARD THROUGH EASTERN MONTANA TO SOUTH CENTRAL SASKATCHEWAN. BY NOON THE FRONT SHOULD BE OVER FAR WESTERN COUNTIES OF NORTH DAKOTA...AND BY EVENING NEAR DICKINSON TO EAST OF WILLISTON. BY MONDAY MORNING THE FRONT SHOULD BE APPROACHING THE RED RIVER VALLEY. CURRENTLY SOUTHEAST WINDS OF 15 TO 20 MPH WITH SOME HIGHER GUSTS...EXCEPT DICKINSON WHICH REPORTED 35 MPH GUSTING TO OVER 45 MPH. THINKING WINDS THERE SHOULD DECREASE DURING THE MORNING. WILL ISSUE WIND ADVISORY MY CENTRAL AND EASTERN COUNTIES...ONE BEGINNING 15Z AND THE JAMESTOWN AREA BEGINNING 18Z. EXPECTING ENOUGH INSTABILITY FOR THUNDERSTORMS THIS AFTERNOON OVER THE WESTERN HALF OF THE STATE...THEN RAIN AND SNOW SHOWERS SPREADING WEST TO EAST TONIGHT AS COLD AIR MOVES IN BEHIND THE COLD FRONT. MODELS HAVE CONSISTENTLY PUT GOOD PRECIP AMOUNTS OF 1/4 TO 1/2 INCH OVER NORTHWEST AND NORTH CENTRAL...WITH LESS THAN A TENTH OF AN INCH SOUTHERN COUNTIES. WEST WINDS MONDAY WITH A CHANCE OF SHOWERS AS UPPER LEVEL VORT ENERGY MOVES ACROSS THE STATE AND THE UPPER LOW LIFTS NORTH INTO CANADA. LONG TERM...WEDNESDAY THROUGH SATURDAY UNSETTLED PATTERN IN THE EXTENDED PERIOD. MODELS BEGIN THE EXTENDED PERIOD IN PRETTY GOOD AGREEMENT WITH HIGH PRESSURE SITUATED OVER THE REGION AND A CLOSED UPPER LOW SITUATED JUST OFFSHORE OF THE WA/OR COAST. WEDNESDAY LOOKS TO BE DRY AND A LITTLE WARMER ACROSS THE SOUTH THAN THE PREVIOUS FORECAST AS SOUTHERLY RETURN FLOW DEVELOPS DURING THE DAY AHEAD OF SURFACE LOW PRESSURE THAT DEVELOPS OVER THE NORTHERN AND CENTRAL HIGH PLAINS IN A BROAD SOUTHWEST UPPER FLOW PATTERN. THIS SURFACE LOW MOVES INTO THE NORTHERN PLAINS WEDNESDAY NIGHT BRINGING A CHANCE OF SHOWERS TO THE AREA. APPEARS TO BE ENOUGH STABILITY FOR SOME THUNDER ACROSS THE SOUTH...AS WELL AS ENOUGH COLD AIR FOR A RAIN/SNOW MIX IN THE WEST LATE WEDNESDAY NIGHT. THE ECMWF IS A BIT QUICKER THAN THE GFS AT THIS POINT BUT STILL ENOUGH AGREEMENT ON QPF PATTERN TO RAISE POPS INTO THE CHANCE CATEGORY ON WEDNESDAY NIGHT. THE GLOBAL GEM ALSO SUPPORTS THIS SCENARIO. MODELS BEGIN TO DIVERGE BEYOND THIS POINT WITH THE ECMWF AND GLOBAL GEM BRINGING AND END TO THE PRECIPITATION FROM WEST TO EAST ON THURSDAY AS THE SYSTEM HEADS EAST. THE GFS ON THE OTHER HAND SLOWS THE SURFACE SYSTEM AS THE UPPER TROUGH CLOSES OFF OVER NORTH DAKOTA BRINGING SIGNIFICANT RAIN AND SNOW TO THE AREA THURSDAY AND THURSDAY NIGHT. THE GFS HAS BEEN THE LEAST CONSISTENT OF THE MODELS AND HAVE LEANED TOWARD AN ECMWF GLOBAL GEM SOLUTION HERE. THUS WE DID KEEP A CHANCE OF RAIN AND SNOW OVER THE CWA ON THURSDAY BUT WENT DRIER THURSDAY NIGHT WITH MAINLY SLIGHT CHANCE POPS. BEYOND THE DAY 4-5 PERIOD...THE GFS KEEPS A COOL AIRMASS OVER THE REGION IN A NORTHWEST FLOW. ECMWF IS MORE ZONAL AND BRINGS A BRIEF WARM UP ON SATURDAY BEFORE COOLING TEMPERATURES DOWN AGAIN ON SUNDAY. AVIATION... SEVERAL PROBLEMS TO DEAL WITH IN THE AVIATION FORECAST TODAY. FIRST WILL BE WINDS AS A LOW PRESSURE SYSTEM CURRENTLY OVER SOUTHEAST MONTANA MAKES IT WAY EAST ACROSS THE CWA BY THE END OF THE 24 HOUR PERIOD. STRONG SOUTHEAST FLOW AHEAD OF THE SYSTEM WILL TURN WEST BEHIND THE SYSTEM. WILL USE LATEST RUC AND NAM WIND GUIDANCE FOR A START ON WIND FORECAST. SECOND PROBLEM WILL BE SHOWER AND POSSIBLE THUNDERSTORM DEVELOPMENT ALONG AND BEHIND THE COLD FRONT THIS AFTERNOON AND EVENING. WILL LIKELY CARRY A PROB30 GROUP FOR THUNDERSTORM ACTIVITY THIS AFTERNOON AND EVENING. AND FINALLY LOW CEILINGS AND VSBYS IN FROZEN PRECIPITATION LATE IN THE PERIOD. WILL HIT NORTHERN ZONES THE HARDEST WITH LOWER CIGS/VSBYS LATE TONIGHT. FIRE WEATHER... STRONG WINDS AND LOW RELATIVE HUMIDITIES ON SATURDAY GAVE RISE TO RED FLAG CONDITIONS. SEVERAL FIRES IGNITED AND WERE DIFFICULT TO CONTROL. WINDS WERE 15 TO 25 MPH AND GUSTY WITH MINIMUM RELATIVE HUMIDITIES OF 15 TO 22 PERCENT. FOR TODAY...EXPECTING WINDS OF 25 TO 35 MPH WITH GUSTS TO 45 MPH TODAY OVER ALL BUT THE FAR WESTERN COUNTIES. THE TROUGH/FRONT IS EXPECTED TO MOVE INTO WESTERN NORTH DAKOTA AROUND NOON AND THE SOUTHEAST WINDS WILL DECREASE DURING THE MORNING...THEN BECOME WESTERLY 15 TO 20 MPH THIS AFTERNOON. FROM ROUGHLY BURKE COUNTY TO GRANT/SIOUX COUNTIES EXPECTING SOUTHEAST WINDS TO INCREASE DURING THE MORNING AND REMAIN IN WIND ADVISORY CRITERIA THROUGH 10 PM CDT. THE MAIN FLY IN THE OINTMENT IS RELATIVE HUMIDITIES...WHICH ARE EXPECTED TO DROP TO 35 TO 40 PERCENT THIS AFTERNOON. THIS RELATIVE HUMIDITY WOULD NORMALLY BE TOO HIGH FOR RED FLAG CRITERIA...HOWEVER BECAUSE OF DORMANT/DRY VEGETATION WITH LITTLE OR NO GREENUP REPORTED...AND SUCH STRONG WINDS EXPECTED...WILL ISSUE THE RED FLAG BEGINNING AROUND 10 AM CDT THIS MORNING AND CONTINUING UNTIL 10 PM CDT TONIGHT. AS THE COLD FRONT PUSHES EASTWARD INTO THE STATE THIS AFTERNOON AND EVENING...THUNDERSTORMS SHOULD BECOME MORE WIDESPREAD...AND THE LOWER LEVELS SHOULD BECOME MORE CONDUCIVE TO PRECIPITATION REACHING THE GROUND. LIGHTNING STRIKES ARE POSSIBLE AND WILL BE A HAZARD WITH DRY FUEL CONDITIONS. PRECIPITATION SHOULD CHANGE OVER INTO A RAIN AND SNOW MIX BEHIND THE COLD FRONT TONIGHT. && .BIS WATCHES/WARNINGS/ADVISORIES... RED FLAG WARNING UNTIL 10 PM CDT /9 PM MDT/ THIS EVENING FOR NDZ002>005-010>013-019>023-025-034>037-042-045>048-050-051. WIND ADVISORY UNTIL 10 PM CDT /9 PM MDT/ THIS EVENING FOR NDZ002>005-010>013-019>023-034>036-042-045>047-050. WIND ADVISORY UNTIL 10 PM CDT THIS EVENING FOR NDZ025-037-048- 051. WIND ADVISORY UNTIL 7 PM CDT /6 PM MDT/ THIS EVENING FOR NDZ018- 033-041-044. && $$ JWS nd AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE GRAND FORKS ND 826 PM CDT SAT APR 19 2008 .UPDATE... THE MAIN ISSUE OVERNIGHT IS WILL LOWER CLOUDS ADVANCE FROM CNTRL AND NE MN INTO NW MN AND SE ND. SATELLITE LAST FEW HOURS HAS SHOWN THE WRN EDGE OF CLOUDS NR AN KAXN-KADC-KINL LINE WITH THICKEST CLOUDS EAST OF THIS LINE WITH CEILINGS IN THE 4500-5500 FT RANGE EVENTUALLY DROPPING TO IFR RANGE OVER FAR ERN MN INTO WI WHERE MOISTURE IS DEEPER ON NORTH SIDE OF VERY SLOW MOVING UPR LOW IN THE SRN GREAT LAKES/OHIO VALLEY. SFC HIGH PRESSURE RIDGE HAS REMAINED INTACT AGAIN TODAY NR AN INL-AXN LINE KEEPING WITH A SHARP CUTOFF AT 925-800 MB LAYER FROM MOISTURE TO THE EAST AND VERY DRY AIR TO THE WEST. 18Z NAM/RUC AND GFS ALL SHOW IDEA THAT THE 850 MB MOISTURE CURRENT AXN-INL EASTWARD WILL START TO MOVE BACK WEST AS 850 MB WINDS TURN MORE SOUTHEAST AND INCREASE OVERNIGHT AS SFC RIDGE WEAKENS AND MOVES EAST AS MONTANA SFC LOW MOVES NORTHEAST INTO CANADA. 21Z RUC SHOW 850 MB MOISTURE NR AXN AREA MOVING NORTHWEST AFTER 06Z INTO WCNTRL MN AND SE ND AT THIS MAY BE CORRECT. SEEING TRENDS THIS EVENING THAT POINT TO THIS IN THAT 40+ DEW PTS HAVE MOVED INTO WHEATON AND WAHPETON PAST FEW HOURS WITH DEW PTS INCREASING INTO THE UPR 30S INTO SE ND AND NE SD. THUS COORD WITH MPX/DLH AND ADDED MORE CLOUD COVER OVERNIGHT TO SOUTHEAST HALF OF THE FCST AREA. DID NOT GO AS WILD AS RUC WOULD SUGGEST UNTIL CLOUD TRENDS ARE MORE SET. DID ALSO INCREASE DEW PTS A BIT IN WCNTRL MN. && .AVIATION...DID BRING IN SOME MVFR CIGS INTO BEMIDJI OVERNIGHT AS 850 MB FLOW TURNS SOUTHEAST 06Z AND AFTER AND KEPT IN SOME MVFR CIGS TIL LATE MORNING SUNDAY. OTHERWISE FOR NOW KEPT IDEA OF JUST SOME INCREASING CIRRUS AT FARGO-GRAND FORKS. SOUTHEAST WINDS BY 15Z SUNDAY INCREASING TO 15-20 KTS IN THE VALLEY WITH 20-30 KTS BY 20Z. && .PREV DISCUSSION... /ISSUED 300 PM CDT SAT APR 19 2008/ SHORT TERM... /TONIGHT THROUGH TUE/ CURRENT H500 PATTERN SHOWING A LOW OVER THE PAC NW AND SECOND LOW OVER THE CENTRAL MISSISSIPPI VALLEY...WITH RIDGING OVER THE CENTRAL AND NORTHERN PLAINS. AT H850...SEEING 40 DM HEIGHT FALLS OVER WA STATE AND WEAK SFC CIRCULATION OVER MT. MAIN FORECAST CHALLENGE WILL BE PRECIP AND CHANCES FOR THUNDER AS ASSOCIATED FRONT PUSHES ACROSS THE FA. IN GENERAL...NAM AND GFS IN FAIR AGREEMENT WITH TIMING HOWEVER...AS USUAL...NAM IS A BIT DRIER. THUS GOING PRIMARILY WITH GFS. GFS SHOWS H700 LOW DEEPEN OVER NRN ROCKIES EARLY SUN...AND DEVELOPMENT OF DECENT BAND OF FRONTOGENESIS BY MID DAY SUNDAY. TIGHTENING SFC GRADIENT WILL RESULT IN SOUTHERLY FLOW PUMPING UP DEW POINTS DRG THE DAY SUN. SFC FRONT THEN PROGGED TO ENTER INTO THE WESTERN FA BY 12Z MON...WITH SHOWALTER INDICES AHEAD OF FRONT RANGING FROM NEG TWO TO NEG 4. BEST INSTABILITY LOOKS TO BE ALONG AND JUST EAST OF VALLEY AT 12Z MON...WITH RAPID RISE IN SHOWALTERS ACROSS THE EAST BY MON AFTERNOON. MAIN CHANGES TO PREV FCST ARE MINOR TWEAKS TO POPS AND TIMING OF FRONT. ELECTED TO NOT BUMP POPS INTO THE CHANCE CAT FOR 00Z TO 06Z MON AS MODELS FAIRLY CONSISTENT WITH KEEPING FRONT WELL TO WEST. BEYOND THAT...MADE MINOR ADJUSTMENTS FOR ORIENTATION OF FRONT HOWEVER DID ADJUST POPS BEHIND FRONT TO MOVE SYSTEM OUT IN LINE WITH 12Z GFS. ALSO CHANGED PRECIP TYPE BEHIND THE TIGHT SHOWALTER GRADIENT TO RAIN WITH ISOLATED THUNDER...VICE PREDOMINANTLY THUNDERSTORMS. LAST ISSUE WAS QPF...APPEARS BOTH HPC AND GFS LIKELY OVERDOING QPF AMOUNTS SO CUT AMOUNTS IN HALF. GFS AND ECMWF BOTH SHOW WEAK SFC LOW DEVELOP IN WRN DAKOTAS BEHIND THIS FRONT...WITH A CHANCE FOR MORE PRECIP IN CNTRL DAKOTA FOR TUE. DID INTRODUCE A SLIGHT CHANCE FOR RAIN SHOWERS IN MY SW. FOR TEMPS...NEWEST MAV GUIDANCE VERY MUCH IN LINE WITH PREV FCST AND MINOR ADJUSTMENTS WERE MADE. LONG TERM... /WED THROUGH SAT/ A BROAD 500 MB TROUGH ACROSS CANADA WILL RESULT IN BELOW NORMAL TEMPERATURES THROUGH THE EXTENDED PERIOD. A CHANCE OF PRECIPITATION RETURNS DURING THE THURSDAY INTO FRIDAY TIME PERIOD AS THE NEXT IN A SERIES OF COLORADO SURFACE CYCLONES TRACKS INTO THE NORTHERN PLAINS. 850 MB TEMPERATURES COOL BELOW 0C THURSDAY NIGHT INTO FRIDAY MORNING. THUS...A MIXTURE OF RAIN AND SNOW SHOWERS HAS BEEN INTRODUCED INTO THIS TIME PERIOD. FIRE WEATHER... CONDITIONS WILL REMAIN NEAR CRITICAL FIRE WEATHER CRITERIA OVER THE DEVILS LAKE BASIN THROUGH THE REST OF THIS AFTERNOON. TOWARDS EVENING...TEMPERATURES WILL COOL SUFFICIENTLY TO BRING RELATIVE HUMIDITIES UP. WINDS WILL GENERALLY REMAIN IN THE 5 TO 10 MPH RANGE WITH AN OCCASIONAL GUST TO 15. OTHERWISE...SOUTHERLY FLOW DEVELOPING THIS AFTERNOON AND EVENING WILL HELP TRANSPORT LOW LEVEL MOISTURE INTO THE CWA...AND WILL INCREASE AHEAD OF LOW PRESSURE DEVELOPING IN THE HIGHT PLAINS. THUS...MINIMUM HUMIDITIES SHOULD RISE INTO THE 32 TO 37 PERCENT RANGE FOR SUNDAY. AS THE GRADIENT TIGHTENS INTO SUNDAY...WINDS ARE EXPECTED TO INCREASE INTO THE 15 TO 20 MPH RANGE...WITH GUSTS OF 25 TO 30 MPH POSSIBLE. && .FGF WATCHES/WARNINGS/ADVISORIES... ND...NONE. MN...NONE. && $$ RIDDLE/SPEICHER/HOPKINS nd AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WILMINGTON OH 157 PM EDT SUN APR 20 2008 .SYNOPSIS... AN UPPER LEVEL LOW ACROSS THE MIDDLE OHIO VALLEY WILL DRIFT SLOWLY SOUTHEAST TOWARD THE CAROLINA COAST THROUGH TONIGHT. UPPER LEVEL RIDGING WILL BUILD INTO THE REGION BEHIND THIS SYSTEM FOR MONDAY AND TUESDAY. && .NEAR TERM /THROUGH TONIGHT/... WILL USE A BLEND OF THE LATEST RUC MODEL AND OPERATIONAL MODELS FOR THE NEAR TERM FORECAST. AN UPPER LEVEL CLOSED LOW WAS LOCATED OVER ERN KY THIS MORNING. THIS LOW IS FCST TO DRIFT SLOWLY SOUTHEAST TODAY...BEING LOCATED OVER NW NORTH CAROLINA BY THIS EVENING. EMBEDDED VORTICITY LOBES ROTATING AROUND THE LOW...ALONG WITH DAYTIME HEATING/WEAK SFC TO 850 MB CONVERGENCE...WILL RESULT IN A CHANCE FOR SHOWERS ACROSS THE REGION. THE BEST CHANCE IS EXPECTED ACROSS THE SE CWFA. THERE WILL BE ENOUGH INSTABILITY IN THIS AREA TO ALSO WARRANT A MENTION OF THUNDER. TEMPERATURES WILL RANGE FROM THE LOWER TO MID 60S. FOR TONIGHT...ANY SHOWER/THUNDERSTORM ACTIVITY WILL END QUICKLY AFTER SUNSET. SKIES WILL BECOME PARTLY CLOUDY. OVERNIGHT LOWS WILL RANGE FROM THE MID TO UPPER 40S. WITH SCATTERED SHOWERS STILL EXPECTED TO INCREASE THIS AFTERNOON...AND WITH TEMPERATURES HEADING TOWARD THE 60S AS FORECAST...NO UPDATE IS NEEDED LATE THIS MORNING. && .SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/... MID LEVEL RIDGING WILL BUILD ACROSS THE OHIO VALLEY AND ERN GREAT LAKES MONDAY THROUGH TUESDAY IN THE WAKE OF THE UPPER LEVEL LOW. THIS PATTERN WILL PROVIDE FOR PARTLY TO MOSTLY SUNNY SKIES DURING THE DAY AND MOSTLY CLEAR CONDITIONS AT NIGHT. HIGHS WILL WARM FROM THE LOWER 70S ON MONDAY TO THE MID AND UPPER 70S ON TUESDAY. FOR TUESDAY NIGHT...A COLD FRONT WILL APPROACH THE REGION FROM THE WEST. HAVE SLOWED THE ONSET OF SHOWERS AND THUNDERSTORMS INTO THE REGION...KEEPING A LOW CHC THREAT LATE TUESDAY NIGHT ACRS THE FAR NW CWFA. && .LONG TERM /WEDNESDAY THROUGH SATURDAY/... WEAK COLD FRONT WILL TRAVERSE OH VLY ON WED. PCPN SHOULD REMAIN SCATTERED AT BEST AS MAIN FORCING REMAINS WELL NORTH OF THE REGION ACRS NRN GRT LKS IN CLOSER PROXIMITY TO SFC LO. WEAK LO LVL CONV AND INSTABILITY WILL LIKELY BE MAIN CONTRIBUTORS TO CONVECTIVE DVLPMNT ON WED. CONSIDERED LOWERING POPS A BIT FOR WED BUT HAVE DECIDED TO CONTINUE TO ROLL WITH 40 POPS. SHOULD MODELS CONTINUE TRENDING TOWARDS WEAKER AND MOISTURE-STARVED FRONT FOR WED...LATER SHIFTS WOULD NEED TO CONSIDER LOWERING POPS BACK INTO THE 20-30% RANGE. FRONT WILL DROP SOUTH AND EAST OF THE REGION WED NIGHT AS SFC HI BUILDS IN ACRS THE GRT LKS. MID LVL RIDGE WILL ONCE AGAIN REESTABLISH ACRS EASTERN CONUS ON THURS...BRINGING DRY PLEASANT WX TO THE REGION. WARM FRONT WILL LIFT NORTH THRU THE OH VLY LATE THURS NIGHT AND INTO FRI IN RESPONSE TO SFC LO MOVING INTO THE UPR MISSISSIPPI VLY. 00Z GFS/ECMWF/UKMET AND MAJORITY OF THE GFS ENSEMBLE MEMBERS HAVE ALL COME INTO REASONABLE AGREEMENT IN TRACKING ASSOCD COLD FRONT THRU THE REGION FRI NIGHT INTO SAT AS SFC LO OCCLUDES NORTH OF THE GRT LKS. WILL CARRY CHANCE POPS THRU THIS PERIOD WITH SCT TSTMS POSSIBLE. SFC HI PRES WILL THEN BUILD IN FOR THE SECOND HALF OF THE WEEKEND. WITH MID LVL RIDGE IN PLACE FOR MUCH OF THE SECOND HALF OF THE WORK WEEK...EXPECT ABV NORM TEMPS TO PERSIST WITH AFTN HIGHS IN THE 70S AND LOWS IN THE U40S AND 50S. WITH ZONAL FLO ALOFT IN WAKE OF FROPA ON SAT...EXPECT COOLER AND MORE SEASONABLE TEMPS WITH HIGHS IN THE 60S AND LOWS IN THE 40S. && .AVIATION /18Z SUNDAY THROUGH FRIDAY/... VFR CONDITIONS WILL PERSIST EARLY IN THE FORECAST. ISOLATED SHOWERS WILL AFFECT TAF SITES BUT ARE NOT LIKELY TO REDUCE CEILINGS OR VISIBILITIES TO MVFR. EXPECT MVFR MIST TO FORM AT ALL SITES STARTING AROUND 05Z CONTINUING TO 13Z. MVFR CEILINGS MAY OCCUR AFTER 13Z AT CMH AND LCK WHERE MODEL SOUNDINGS INDICATE A RETURN OF LOW LEVEL MOISTURE ON THE BACK SIDE OF THE UPPER LOW. OUTLOOK...MVFR CEILINGS WILL BE POSSIBLE IN SCATTERED SHOWERS AND THUNDERSTORMS LATE TUESDAY NIGHT AND WEDNESDAY MORNING. && .ILN WATCHES/WARNINGS/ADVISORIES... OH...NONE. KY...NONE. IN...NONE. && $$ SYNOPSIS...HICKMAN NEAR TERM...CONIGLIO/HICKMAN SHORT TERM...HICKMAN LONG TERM...RYAN AVIATION...CONIGLIO oh AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CLEVELAND OH 550 PM EDT SAT APR 19 2008 .SYNOPSIS... WEAKENING LOW PRESSURE OVER LOWER MICHIGAN WILL REMAIN NEARLY STATIONARY INTO SUNDAY AS A SECONDARY LOW PRESSURE AREA FORMS OVER VIRGINIA AND DRIFTS SLOWLY SOUTHEAST INTO NORTH CAROLINA ON MONDAY. HIGH PRESSURE OFF THE NEW ENGLAND COAST WILL REMAIN NEARLY STATIONARY AND SPREAD BACK SOUTHWESTWARD EARLY NEXT WEEK. && .NEAR TERM /UNTIL 6 AM SUNDAY/... THE REGION IS IN THE DEFORMATION ZONE ON THE EAST SIDE OF THE LOW TONIGHT AND AS THE LOW BECOMES NEGATIVELY TILTED A STRONG SE FLOW AT 850 MB TRIES TO TAP MOISTURE FROM THE MID ATLANTIC COAST AND SEND IT NW TOWARD NW PA BY SUNDAY. THE NAM IS MORE PRONOUNCED WITH THIS SE FLOW THAN THE GFS. BOTH THE GFS AND NAM PRODUCED A MOD TO LARGE AMOUNT UVM TONIGHT SO EXPECT NUMEROUS SHOWERS WITH ISOLATED THUNDER. HAVE ADJUSTED POPS FOR THIS EVENING TO SHOW HIGHER INITIAL POP FOR MORE LAKESHORE COUNTIES AND HAVE ADDED THUNDER FOR ALL BUT NW PA WHERE PRECIP PROB WL NOT OCCUR UNTIL AIRMASS HAS STABILIZED MORE LATER THIS EVENING. && .SHORT TERM /6 AM SUNDAY THROUGH MONDAY NIGHT/... THE CUT OFF LOW MAKES GRADUAL PROGRESS TO THE EAST JUST SOUTH OF THE REGION SUNDAY INTO MONDAY. SOME SUBSIDENCE IS INDICATED FROM SUNDAY OVER THE WESTERN COUNTIES SO I DON`T EXPECT MUCH MORE THAN A SCATTERED MORNING SHOWER. LIKELY POPS ARE IN STORE FOR THE EAST HALF WITH THE MOIST SE FLOW A LOW LEVELS PERSISTING. THE SE LOW LEVEL FLOW WILL WEAKEN MONDAY AND ALLOW SOME DRYING TO TAKE PLACE. GFS GUIDANCE SEEMS REASONABLE. && .LONG TERM /TUESDAY THROUGH SATURDAY/... SIDED WITH THE MORE CONSISTENT AND MUTUALLY AGREED UPON ECWMF FOR THE EXTENDED WHICH BRINGS A FRONT IN A WEAKENED STATE ACROSS WEDNESDAY AND THEN A MORE SIGNIFICANT FRONT FOR SATURDAY. WITH NO REAL CHILLY AIR BEHIND THE NEAR/SHORT TERM SYSTEM...HAVE HIGHS IN THE 70S FOR TUESDAY AND ONLY BACKING OFF A FEW FOR WED/THU. TEMPS CLIMB AGAIN FRI AS WED/THU FRONT WILL PROBABLY LIFT NORTHWARD AS A WARM FRONT. COLD FRONT SATURDAY. && .AVIATION /19Z SATURDAY THROUGH THURSDAY/... SURFACE AND UPPER LEVEL LOW CONTINUE TO SPIN AND MAKE SLOW ESE PROGRESS INTO THE OHIO VALLEY TODAY. SURFACE TROUGH/WIND SHIFT MOVED ACROSS FROM SW TO NE TURNING WINDS SOUTHWEST THIS MORNING. SE FLOW CONTINUES FOR NW PA. DRY AIR IN PLACE HAS MADE PRECIP IMPOSSIBLE THUS FAR ACROSS THE AREA. FOR THE REST OF THE AFTERNOON...FIRST CONCERN IS LAKE BREEZE. ATYPICAL TODAY WITH SOME SYNOPTIC INFLUENCE BUT LAKE BREEZE ALREADY AT DKK AND AND BKL. FOR ERI TROUGH/WIND SHIFT EMANATING FROM SFC LOW TO DISRUPT LAKE BREEZE SOMEWHAT AND HAVE WINDS COMING AROUND TO THE EAST-NE AT MOST. THEY MAY SWING EITHER WAY. FOR CLE WE MAY TEND MORE WEST THIS AFTERNOON WITH A POSSIBILITY THAT THE LAKE BREEZE WILL PULL US TO THE WNW. WIND FORECAST ON CURRENT CONDITIONS AND RUC FORECAST. ALL OF THIS RELAXES THIS EVENING AND WINDS AREA WIDE WILL PRETTY MUCH GO LIGHT/VARIABLE WITH THE BROAD AND WEAK LOW OVER OHIO. PREVAILING VFR CONDITIONS EVEN IF WE DO GET A FEW SHOWERS IN TO THE AREA THIS AFTERNOON. POSSIBILITY FOR A RUMBLE OF THUNDER BUT CHANCES SLIM AND THEREFORE NOT IN TAFS/EXCEPT FDY/. DELAYED THE START OF ANY SHRA. BEST CHANCES LOOK TO BE CENTRAL AND WESTERN PORTIONS AS MOISTURE/SHOWERS FROM CENTRAL OHIO AND ADDITIONAL DEVELOPMENT ACROSS WV IS EXPECTED. THIS AREA HAS NICE CONNECTION TO ATLANTIC FEED. ALSO ACROSS THE EAST CAPE VALUES WILL BE ABLE TO MOUNT SOME. VFR CIGS/VSBY TO GIVE WAY TO MVFR AS LOW GETS CLOSER...AFTER MIDNIGHT. HAVE CONTINUED WITH PREVIOUS FORECAST...TRENDED THE FORECAST TO SHOW POSSIBLE IFR CONDITIONS AFTER 06Z BUT CONFIDENCE IN THIS OCCURRING IS LOW. MAV GUIDANCE SHOWS LIFR CONDITIONS AT MOST SITES AT 12Z SUNDAY BUT THIS SEEMS TOO PESSIMISTIC GIVEN SOUTHWESTERLY FLOW AND CLIMATOLOGY TO THE CONTRARY. OUTLOOK...MVFR CIGS WILL BE POSSIBLE DURING THE DAY ON SUNDAY BUT SHOULD GIVE WAY TO VFR CONDITIONS ON MONDAY. COLD FRONT AND EXPECTED TO SWEEP THROUGH THE TERMINALS WEDNESDAY MORNING...COULD SEE BRIEF RESTRICTIONS TO MVFR/IFR ALONG THE FRONT BUT THIS SHOULD BE SHORT LIVED WITH VFR CONDITIONS RETURNING WEDNESDAY NIGHT. && .MARINE... LIGHT AND VARIABLE FLOW ON THE LAKE THIS AFTERNOON...WITH ONSHORE FLOW ALONG THE NEARSHORE REGION. SLOW MOVING WEAK SYSTEM MOVING THROUGH THE OHIO VALLEY WILL KEEP LGT/VARIABLE FLOW ACROSS THE LAKE THROUGH SUNDAY AND A CHANCE FOR SHOWERS. MORE UNIFORM ESE FLOW TO DEVELOP MONDAY AS A RIDGE BUILDS IN. COLD FRONT WEDNESDAY WILL BRIEFLY BRING WINDS AROUND THE DIAL TO THE NW AND NORTH AND TO ENE WITH HIGH PRESSURE FOR THURSDAY. && .CLE WATCHES/WARNINGS/ADVISORIES... OH...NONE. PA...NONE. MARINE...NONE. && $$ SYNOPSIS...REL NEAR TERM...ADAMS SHORT TERM...REL/ADAMS LONG TERM...OUDEMAN AVIATION...OUDEMAN MARINE...OUDEMAN oh AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CLEVELAND OH 154 PM EDT SAT APR 19 2008 .SYNOPSIS... WEAKENING LOW PRESSURE OVER ILLINOIS WILL MOVE EASTWARD TO LOWER MICHIGAN BY TONIGHT. THE LOW WILL DRIFT SOUTHEAST ACROSS OHIO TONIGHT TO THE CENTRAL APPALACHIANS ON SUNDAY AND CAROLINA COAST ON MONDAY. HIGH PRESSURE WILL REMAIN NEARLY STATIONARY ACROSS EASTERN CANADA AND SPREAD BACK SOUTHWESTWARD EARLY NEXT WEEK. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... CURRENT FORECAST LOOKS GOOD SO ONLY MINOR CHANGES PLANNED. MOSTLY SUNNY SKIES OVER NE OH AND NW PA WITH DOWNSLOPE SE FLOW HAS ALLOWED TEMPS TO RISE INTO THE 70S ALREADY. WILL RAISE TEMPS TO NEAR 80 THERE. PCPN ROTATING AROUND THE IL UPPER LOW IS HAVING TROUBLE FILLING IN AS BOUNDARY LAYER IS STILL RATHER DRY. A LARGER AREA OF SHOWERS OVER WV IS MOVING NORTH AND MAY REACH THE REGION BY MID AFTERNOON. HAVE DROPPED THE MENTION OF THUNDERSTORMS FOR THE AFTERNOON WITH LIMITED INSTABILITY. && .SHORT TERM /6 PM THIS EVENING THROUGH TUESDAY NIGHT/... AS SYSTEM GETS TOTALLY CUT OFF THERE WILL ESSENTIALLY BE NO GULF INFLOW BY TONIGHT. PCPN WILL BECOME DEPENDENT STRICTLY ON UPWARD MOTION WHICH WILL BE ENHANCED AT NIGHT BY THE LOW LEVEL JET AND DURING THE DAY BY CONVECTIVE PROCESS. THE MAIN AREA OF SHOWERS SHOULD SHIFT OFF TO THE ESE LATER TONIGHT AND THROUGH THE DAY SUNDAY AS LARGE DRY SURFACE HIGH REMAINS BLOCKED OVER E CANADA AND UPPER LOW GETS KNUCKLED UNDER THE RIDGE TOWARD THE CAROLINAS. SHOULD SEE A FAIR AMOUNT OF CLOUDS LINGER ON SUNDAY WITH A GRADUAL THINNING INTO MONDAY. SHOWERS SHOULD DECREASE ACROSS NW OHIO TONIGHT. WILL NOT GO AS HIGH AS GFS GUIDANCE POPS ON SUNDAY FOR NE OH/NW PA. THE SHOWERS WILL REACH THE DEFORMATION ZONE ALOFT AND COULD LINGER IN THAT AREA BUT WITH DOWNSLOPE SSE FLOW CONTINUING AND THE VARIABILITY IN THE MODELS DO NOT HAVE ENOUGH CONFIDENCE TO PIN DOWN THAT PARTICULAR AREA AND WILL GENERALLY HAVE "CHANCE" POPS ON SUNDAY. AIRMASS WILL BE EXCHANGED IN MOST AREAS ON SUNDAY WITH THE POSSIBLE EXCEPTION OF NW PA AND SHOULD SEE COOLER TEMPS FILTER BACK TO ALL AREAS. AREAS THAT GET THE MOST SHOWERS WILL SEE TEMPS DEPRESSED THE MOST WHILE AREAS THAT HAVE LITTLE RAIN WILL SEE TEMPS SNEAK UP TOWARD THE UPPER 60S OR 70. MONDAY TRICKY IN THE FACT THAT THE AXIS OF HIGHER THETA E AND SURFACE TROUGH MAY LINGER. MY FIRST THOUGHT WAS THAT IT MIGHT GET CONVECTIVE AND NEW SHOWERS AND THUNDERSTORMS MIGHT POP UP. MODELS DO NOT SHOW MUCH INSTABILITY THOUGH. CANNOT RULE OUT A LINGERING SHOWER...MAINLY N CENTRAL AND NE OH. WILL CONTINUE WITH A 20 POP (SLIGHT CHANCE) ON MONDAY. ENOUGH SUBSIDENCE AND RIDGING BY TUESDAY THAT IT SHOULD BE DRY. TEMPS WILL REBOUND A CATEGORY OR TWO ON TUESDAY AS SOUTH FLOW GET REESTABLISHED. && .LONG TERM /WEDNESDAY THROUGH SATURDAY/... EXTENDED PORTION OF THE FORECAST STARTS WITH A COLD FRONTAL PASSAGE WEDNESDAY MORNING. THE ECMWF GFS AND GFS ENSEMBLE MEAN ALL MOVE THIS FRONT THROUGH THE FORECAST AREA BY WEDNESDAY AFTERNOON WITH HIGH PRESSURE RAPIDLY BUILDING BEHIND THE FRONT WEDNESDAY EVENING. MADE SOME ADJUSTMENTS TO THE FORECAST AND WENT WITH A MORE OPTIMISTIC APPROACH WEDNESDAY NIGHT THROUGH THURSDAY NIGHT. WITH STRONG HIGH PRESSURE EXPECTED TO BUILD SOUTHWARD FROM ONTARIO...WILL GO WITH A DRY FORECAST THROUGH THURSDAY EVENING. ALSO EXPECTING TO SEE A FAIR AMOUNT OF SUN DURING THE DAY ON THURSDAY AND DECREASED FORECAST CLOUD COVER. MODEL DISCREPANCIES MAKE THEMSELVES APPARENT THURSDAY NIGHT THROUGH THE END OF THE WEEK AS THE GFS MAINTAINS DRY CONDITIONS WHILE THE EURO BRINGS A WAVE UP THE OHIO VALLEY BY FRIDAY MORNING. THE ECMWF SOLUTION TENDS TO AGREE MORE WITH THE 18Z GFS...THUS MAKING THE 00Z GFS SOLUTION THE OUTLIER AND HAVE DISCARDED IT ACCORDINGLY. WILL MAINTAIN CHANCE POPS DURING THE DAY ON FRIDAY. WHILE THE 00Z GFS SHOWS A DECAYING COLD FRONT SWEEPING THROUGH OHIO/PENNSYLVANIA FRIDAY...AM HESITANT TO BITE OFF ON THIS SOLUTION ENTIRELY GIVEN THE VARIETY OF MODEL SOLUTIONS. && .AVIATION /17Z SATURDAY THROUGH WEDNESDAY/... SURFACE AND UPPER LEVEL LOW CONTINUE TO SPIN AND MAKE SLOW ESE PROGRESS INTO THE OHIO VALLEY TODAY. SURFACE TROUGH/WIND SHIFT MOVED ACROSS FROM SW TO NE TURNING WINDS SOUTHWEST THIS MORNING. SE FLOW CONTINUES FOR NW PA. DRY AIR IN PLACE HAS MADE PRECIP IMPOSSIBLE THUS FAR ACROSS THE AREA. FOR THE REST OF THE AFTERNOON...FIRST CONCERN IS LAKE BREEZE. ATYPICAL TODAY WITH SOME SYNOPTIC INFLUENCE BUT LAKE BREEZE ALREADY AT DKK AND AND BKL. FOR ERI TROUGH/WIND SHIFT EMANATING FROM SFC LOW TO DISRUPT LAKE BREEZE SOMEWHAT AND HAVE WINDS COMING AROUND TO THE EAST-NE AT MOST. THEY MAY SWING EITHER WAY. FOR CLE WE MAY TEND MORE WEST THIS AFTERNOON WITH A POSSIBILITY THAT THE LAKE BREEZE WILL PULL US TO THE WNW. WIND FORECAST ON CURRENT CONDITIONS AND RUC FORECAST. ALL OF THIS RELAXES THIS EVENING AND WINDS AREA WIDE WILL PRETTY MUCH GO LIGHT/VARIABLE WITH THE BROAD AND WEAK LOW OVER OHIO. PREVAILING VFR CONDITIONS EVEN IF WE DO GET A FEW SHOWERS IN TO THE AREA THIS AFTERNOON. POSSIBILITY FOR A RUMBLE OF THUNDER BUT CHANCES SLIM AND THEREFORE NOT IN TAFS/EXCEPT FDY/. DELAYED THE START OF ANY SHRA. BEST CHANCES LOOK TO BE CENTRAL AND WESTERN PORTIONS AS MOISTURE/SHOWERS FROM CENTRAL OHIO AND ADDITIONAL DEVELOPMENT ACROSS WV IS EXPECTED. THIS AREA HAS NICE CONNECTION TO ATLANTIC FEED. ALSO ACROSS THE EAST CAPE VALUES WILL BE ABLE TO MOUNT SOME. VFR CIGS/VSBY TO GIVE WAY TO MVFR AS LOW GETS CLOSER...AFTER MIDNIGHT. HAVE CONTINUED WITH PREVIOUS FORECAST...TRENDED THE FORECAST TO SHOW POSSIBLE IFR CONDITIONS AFTER 06Z BUT CONFIDENCE IN THIS OCCURRING IS LOW. MAV GUIDANCE SHOWS LIFR CONDITIONS AT MOST SITES AT 12Z SUNDAY BUT THIS SEEMS TOO PESSIMISTIC GIVEN SOUTHWESTERLY FLOW AND CLIMATOLOGY TO THE CONTRARY. OUTLOOK...MVFR CIGS WILL BE POSSIBLE DURING THE DAY ON SUNDAY BUT SHOULD GIVE WAY TO VFR CONDITIONS ON MONDAY. COLD FRONT AND EXPECTED TO SWEEP THROUGH THE TERMINALS WEDNESDAY MORNING...COULD SEE BRIEF RESTRICTIONS TO MVFR/IFR ALONG THE FRONT BUT THIS SHOULD BE SHORT LIVED WITH VFR CONDITIONS RETURNING WEDNESDAY NIGHT. && .MARINE... LIGHT FLOW ON THE LAKE TODAY WITH NORTHEASTERLY WINDS EVENTUALLY BECOMING SOUTHEASTERLY LATE TONIGHT. SURFACE AND UPPER LEVEL LOW PRESSURE EXPECTED TO MOVE OVERHEAD AND DISSIPATE SUNDAY AFTERNOON WHILE HIGH PRESSURE BUILDS ACROSS THE LAKE FROM THE NORTH. WINDS WILL RETURN TO NORTHEASTERLY LATE SUNDAY NIGHT AND MAINTAIN AN EASTERLY COMPONENT THROUGH TUESDAY. LOW PRESSURE AND A COLD FRONT WILL APPROACH LAKE ERIE FROM THE WEST WEDNESDAY MORNING WITH WINDS VEERING TO SOUTHERLY TUESDAY NIGHT...THEN COMING AROUND OUT OF THE WEST WEDNESDAY AFTERNOON. AT THIS POINT GIVEN THE TIMING OF THE FRONT AND ITS WEAK NATURE...NOT EXPECTING WINDS TO REACH SMALL CRAFT ADV CRITERIA. && .CLE WATCHES/WARNINGS/ADVISORIES... OH...NONE. PA...NONE. MARINE...NONE. && $$ SYNOPSIS...KOSARIK NEAR TERM...REL SHORT TERM...KOSARIK LONG TERM...LEINS AVIATION...OUDEMAN MARINE...LEINS oh AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NORMAN OK 1020 AM CDT SUN APR 20 2008 .UPDATE... AGAIN TODAY MADE SOME MINOR CHANGES TO TODAYS GRIDS BASED ON MORNING TRENDS AND LATEST RUC. MORE CLOUD COVER WILL MAKE AFTN HIGH TEMP FORECAST A LITTLE MORE TRICKY TODAY... BUT THICKER BATCH OF CLOUDS WILL SHIFT EAST LATER TODAY AND MANY LOCATIONS SHOULD GET NEAR YESTERDAYS READINGS. WINDS WILL ALSO BECOME QUITE STRONG THIS AFTN... BUT THESE SHOULD AID IN INCREASING LOW LEVEL MOISTURE WHICH WILL KEEP AFTN HUMIDITIES FROM DROPPING TOO MUCH. STILL APPEARS THAT WE CAN GO WITHOUT ANY FIRE WX HEADLINES TODAY. UPDATES OUT SHORTLY. 30 --------------------------------------------------- 350 AM CDT SUN APR 20 2008 .DISCUSSION... THE UPPER RIDGE OVER THE SOUTHERN PLAINS WILL BE SHIFTING EAST OF THE AREA TODAY AS A LARGE UPPER LOW DOMINATES NEARLY THE WESTERN HALF OF THE COUNTRY. A DEEPENING SURFACE LOW PRESSURE TROUGH ALONG THE LEE OF THE ROCKIES WILL RESULT IN INCREASING SOUTH WINDS OVER THE AREA TODAY. THE STRONG WINDS WILL BEGIN PULLING GULF MOISTURE NORTH TOWARDS THE AREA... ALTHOUGH WITH 60 DEGREE DEWPOINTS JUST NOW REACHING THE LOWER TEXAS COAST... THE NAM MAY BE A LITTLE FAST IN PULLING 60 DEWPOINTS INTO WEST CENTRAL OKLAHOMA BY LATE AFTERNOON. MEANWHILE... A LEAD SHORT WAVE MOVING AROUND THE WESTERN LOW WILL TRACK MAINLY TO THE NORTH OF OUR AREA AS IT LIFTS NE THROUGH THE CENTRAL AND NORTHERN PLAINS. TO OUR SOUTH... A SECOND UPPER WAVE THAT WILL BE MOVING EAST OUT OF NORTHERN MEXICO BUT IT WILL LIKELY STAY TO OUR SOUTH IN TEXAS. IT STILL APPEARS THAT THE DRYLINE WILL BECOME ESTABLISHED JUST WEST OF THE CWA THIS AFTERNOON WHICH IN TURN SHOULD KEEP HUMIDITIES ABOVE 20 PCT IN FAR WESTERN PARTS OF OK AND N-TX. WHILE WILDFIRE CONCERNS WILL BE HEIGHTENED BECAUSE OF THE STRONGER WINDS... THE INCREASING LOW LEVEL MOISTURE WILL LIKELY HELP TO KEEP CONDITIONS BELOW CRITICAL LEVELS. OVER THE NEXT FEW DAYS... WE WILL SEE MUCH OF THE ENERGY ASSOCIATED WITH THE LARGE WESTERN LOW CONTINUE TO TRACK MAINLY TO THE NORTH OF THE AREA... BUT CLOSE ENOUGH TO PUSH AN OCCASIONAL FRONT INTO THE SOUTHERN PLAINS. THE FIRST WEAK COLD FRONT WILL MOVE THROUGH ABOUT THE WESTERN HALF OF THE CWA EARLY MONDAY BEFORE BECOMING STATIONARY BY LATE AFTERNOON. WE WILL MAINTAIN LOW POPS FOR PARTS OF NORTH CENTRAL OKLAHOMA FOR MONDAY NIGHT WHERE LIFTING OVER THE FRONT MIGHT GENERATE A STORM OR TWO. HOWEVER... MODEL SOUNDINGS CONTINUE TO SHOW A DECENT CAP OVER MOST OF THE AREA THAT WOULD SUPPRESS MORE WIDESPREAD CONVECTION. ANOTHER WAVE MOVING THROUGH THE CENTRAL PLAINS ON TUESDAY SHOULD HELP PUSH THE FRONT BACK SOUTH ACROSS AREA MONDAY NIGHT AND TUESDAY. WE WILL MAINTAIN A MENTION OF T-STORMS OVER AT LEAST PART OF THE AREA FOR MUCH OF THE UPCOMING WORK WEEK AS UPPER WAVES MOVING OUT OF THE LARGE WESTERN TROUGH CONTINUE TO BRUSH THE AREA... WHILE VARIOUS FRONTS TRAVERSE BACK AND FORTH THROUGH THE AREA. THE MAIN ADJUSTMENTS MADE TO THE GFS MAV/MEX GUIDANCE INCLUDED... MONDAY NIGHT - PULLING THE MAV 20 PCT POPS A LITTLE FARTHER WEST TO INCLUDE SOME OF OUR SE ZONES WHERE CONVERGENCE ON A FRONT AND DEEPER MOISTURE MAY BE SUFFICIENT TO OVERCOME THE CAP IN A FEW PLACES. TUESDAY - COOLED THE MAV HIGH TEMPS IN THE NORTH TO ACCOUNT FOR THE COLD FRONT MOVING THROUGH THE AREA AND TO IMPROVE CONSISTENCY WITH GFE GRIDDED TEMPS AND SURROUNDING OFFICES. THURSDAY - SMOOTHED OUT AN APPARENT LOCAL TEMPERATURE ANOMALY DEPICTED IN NW WOODWARD COUNTY WHERE THE MEX MAX TEMPERATURE GUIDANCE WAS 8 TO 10 DEGREES COOLER THAN NEARBY SURROUNDING AREAS. && .PRELIMINARY POINT TEMPS/POPS... OKLAHOMA CITY OK 82 59 81 61 / 0 10 0 10 HOBART OK 83 58 86 58 / 0 10 10 10 WICHITA FALLS TX 84 65 88 62 / 0 10 0 10 GAGE OK 87 48 83 51 / 0 10 10 10 PONCA CITY OK 81 60 79 62 / 0 10 0 20 DURANT OK 79 63 82 67 / 0 10 0 10 && .OUN WATCHES/WARNINGS/ADVISORIES... OK...NONE. TX...NONE. && $$ 26/32 ok AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NORMAN OK 925 AM CDT SAT APR 19 2008 .UPDATE... WILL GO AHEAD AND SEND AN UPDATE TO ADDRESS SOME CHANGES MADE TO THE GRIDS WRT TO TEMPS AND WINDS TODAY ALONG WITH SOME CHANGES TO MIXING HEIGHTS/TRANSPORT WINDS FOR FIRE WX. MUCH OF THE CHANGES BASED ON MORNING TRENDS AND LATEST RUC FORECAST. UPDATES OUT SHORTLY. 30 ----------------------------------------------------------- 502 AM CDT SAT APR 19 2008 .DISCUSSION... WARMER TEMPERATURES AND DRY WEATHER ARE EXPECTED TODAY AS SOUTH WINDS RETURN TO THE REGION WHILE AN UPPER LEVEL RIDGE TRANSLATES ACROSS SOUTHERN PLAINS. SKIES WILL START OUT CLEAR THIS MORNING ALTHOUGH SOME CIRRUS MAY SPREAD INTO THE SOUTHWEST PART OF THE AREA THIS AFTERNOON. SOUTH WINDS WILL INCREASE QUITE A BIT ON SUNDAY OVER MUCH OF THE AREA AS THE LEE TROUGH DEEPENS TO OUR WEST. THE WINDS WILL BEGIN TO PULL MORE MOISTURE... AND SOME LOWER CLOUDS... NORTH INTO THE AREA BY LATE IN THE DAY. THE DRYLINE IS ALSO FORECAST TO BECOME BETTER DEFINED NEAR THE WESTERN OK-TX PANHANDLE BORDER IN RESPONSE TO VEERING WINDS OVER WEST TEXAS AND THE MOISTURE RETURN TO THE EAST. ALTHOUGH THE WINDS WILL BE INCREASING THROUGH THE WEEKEND... UNCERTAINTY REMAINS REGARDING HOW SIGNIFICANT THE FIRE WEATHER CONCERNS WILL BE FOR OUR FAR WESTERN TIER OF COUNTIES. FOR THIS AFTERNOON... THE MINIMUM HUMIDITIES WILL LIKELY BE NEAR OR BELOW 20 PERCENT IN THE FAR WEST BUT THOSE AREAS MAY NOT REACH WIND SPEED CRITERIA UNTIL RATHER LATE IN THE AFTERNOON. FOR SUNDAY... THERE IS STILL UNCERTAINTY CONCERNING THE EXACT LOCATION OF WHERE THE DRYLINE WILL SET UP. THE ECMWF LIKELY IS MIXING THE MOISTURE OUT TOO FAR TO THE EAST...WHILE THE GFS AND NAM MIGHT BE JUST A BIT TOO MOIST IN THE FAR WEST. THE NAM WAS ALSO LOWERING THE WIND SPEEDS NEAR AND BEHIND THE DRYLINE IN THE AFTERNOON. FOR NOW... WE DO NOT PLAN TO ISSUE A WATCH. FARTHER WEST... A LARGE UPPER TROUGH WILL BE SETTLING INTO THE WESTERN U.S. THROUGH THE WEEKEND AND WILL BEGIN SPREADING ITS INFLUENCE INTO THE SOUTHERN PLAINS BY LATE SUNDAY. CONCERNING THE T-STORM CHANCES FOR THE UPCOMING WEEK... THE EARLIEST POSSIBILITY FOR STORMS WOULD BE LATE SUNDAY NEAR THE DRY LINE. HOWEVER... MODEL SOUNDINGS SUGGEST THAT MOISTURE WILL STILL BE RATHER SHALLOW... WHILE A MID LEVEL CAP STRENGTHENS OVER THE AREA. A LEAD SHORT WAVE MOVING OUT OF THE WESTERN TROUGH WILL LIKELY BE TOO FAR NORTH TO CONTRIBUTE MUCH UPPER SUPPORT. GIVEN THESE FACTORS... WE WILL NOT MENTION STORMS FOR SUNDAY. ANOTHER UPPER WAVE MAY BRUSH NORTH CENTRAL OKLAHOMA MONDAY NIGHT WHICH COULD RESULT IN A FEW STORMS IN THAT AREA. T-STORM CHANCES INCREASE A BIT MORE WEDNESDAY AND THURSDAY AS A FRONT MOVES INTO THE REGION. SINCE CONFIDENCE IN THE MODELS STARTS TO FALL OFF ABOUT THIS TIME... SO WILL NOT GET TOO CARRIED AWAY WITH POPS AT THIS POINT. REGARDING THE DECREASING CONFIDENCE IN THE MODELS BY MIDWEEK... THE GFS AND ECMWF 500 MB PATTERNS START TO MOVE OUT OF PHASE FROM EACH OTHER BY THAT TIME. THE ECMWF HOLDS ONTO A BROAD TROUGH OVER THE WESTERN U.S. WHILE THE OPERATIONAL GFS IS PROGRESSIVE WITH MOVING AN UPPER RIDGE INTO THE WESTERN US. THE OPERATIONAL GFS ALSO HAS MUCH MORE AMPLITUDE IN A WAVE THAT MOVES INTO THE UPPER MIDWEST TUESDAY NIGHT WHILE THE ECMWF DAMPENS THE WAVE QUITE A BIT. THE NET RESULT OF THESE DIFFERENCES IS THAT THE GFS PUSHES A STRONGER COLD FRONT SOUTH INTO THE SOUTHERN PLAINS. THE MEX GUIDANCE REFLECTS THIS SOLUTION IN COOLING TEMPERATURES SEVERAL DEGREES IN MANY LOCATIONS FOR THE PERIOD TUES NIGHT THROUGH EARLY FRI AS COMPARED TO THE PAST MODEL RUNS. THE CONFIDENCE IN THIS SOLUTION IS NOT HELPED BY THE FACT THAT THE GFS ENSEMBLE MEMBERS EXHIBIT SIGNIFICANT VARIABILITY IN THIS TIME PERIOD WHILE THE ENSEMBLE MEAN HEIGHTS DO INDICATE A LOW AMPLITUDE TROUGH TO OUR WEST... A SOLUTION THAT MORE CLOSELY MIRRORS THE ECMWF RATHER THAN THE OPERATIONAL GFS. GIVEN THE UNCERTAINTIES SURROUNDING THE NEW TREND OF THE GFS TO DEPICT GREATER COOLING NEXT WEEK AND THAT MOST OF OUR SURROUNDING OFFICES ARE HANGING ON TO WARMER TEMPERATURES FOR NOW... WE WILL DISCARD THIS PART OF THE MEX TEMPERATURE GUIDANCE AND KEEP THE CURRENT TEMPERATURE FORECAST FOR MID WEEK. WE WILL ALSO ADJUST WIND DIRECTIONS MORE CLOSELY MATCH TO THE ECMWF GUIDANCE. && .PRELIMINARY POINT TEMPS/POPS... OKLAHOMA CITY OK 79 53 78 58 / 0 10 10 10 HOBART OK 81 54 82 57 / 0 10 10 10 WICHITA FALLS TX 83 55 83 62 / 0 10 10 10 GAGE OK 84 48 84 48 / 0 10 10 10 PONCA CITY OK 76 51 79 60 / 0 10 10 10 DURANT OK 80 54 80 64 / 0 0 0 10 && .OUN WATCHES/WARNINGS/ADVISORIES... OK...NONE. TX...NONE. && $$ 26/32 ok AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE STATE COLLEGE PA 202 AM EDT SUN APR 20 2008 .SYNOPSIS... AN AREA OF HIGH PRESSURE OVER NOVA SCOTIA WILL HELP TO PROVIDE A PERSISTENT SOUTHEASTERLY FLOW OF AIR OVER THE NEXT FEW DAYS AND INCREASE THE CHANCE FOR SHOWERS AS UPPER LOW PRESSURE SLOWLY DRIFTS ACROSS THE CENTRAL APPALACHIANS. SOME PORTIONS OF SOUTH CENTRAL PENNSYLVANIA AND THE LAUREL HIGHLANDS COULD SEE AN INCH OR TWO OF RAINFALL OVER THE NEXT 48 HOURS. COOLER AND UNSETTLED WEATHER WILL ACCOMPANY THIS LOW PRESSURE SYSTEM FOR THE LATTER HALF OF THE WEEKEND INTO EARLY NEXT WEEK. && .NEAR TERM /THROUGH TODAY/... BANDS OF SHOWERS (SOME BRIEFLY HEAVY) WERE TRAINING NNWD AND ACROSS THE LAUREL HIGHLANDS ATTM. 12 KM NAM AND 13 KM RUC APPEAR TO BEE AT LEAST SEVERAL HOURS TOO SLOW AND LIKELY TOO LIGHT WITH THE QPF FROM THESE RAIN BANDS. INCREASED POPS ACROSS THE WRN MTNS AND SCENT ZONES AFTER MIDNIGHT TO LIKELY OR CATEGORICAL WITH AROUND ONE QUARTER OF AN INCH EXPECTED BY 12Z ACROSS THE LAUREL HIGHLANDS. MINOR DOWNWARD ADJUSTMENTS MADE TO TEMPS...AS RAIN STARTS TO COOL THE VERY DRY LOW TO MID LEVELS ACROSS THE SOUTH AND WEST LATE TONIGHT. && .SHORT TERM /TONIGHT THROUGH 6 PM MONDAY/... CONTINUED SLOW EASTWARD PROGRESSION OF UPPER LVL LOW. LATEST SOLUTIONS BEGINNING TO SLIDE SHORTWAVE TO THE SE SUN MORNING...WITH A CENTER OVER EXTREME SE KY BY SUNRISE. THIS WILL AID IN SLIDING THE BEST PRECIP CHANCES FURTHER SOUTH...MAINLY ALONG AND SOUTH OF I-80. FEEL THAT WITH THE WEAK RIDGE SLIDING OVERTOP FROM QUEBEC...THIS WILL AID IN STEERING VORT FURTHER SE AND MAY EVEN FILTER IN SOME DRY LOW/MID-LVL MOISTURE. HAVE MAINTAINED CATEGORICAL POPS GIVEN CONSISTENCY AND PROXIMITY OF LLJ...DESPITE LATEST BUMP IN TRACK TO THE SOUTH. MIXED LYR SHOULD TAP PORTION OF LLJ...SO COULD SEE GUSTS UP TO 30MPH IN NUMEROUS LOCATIONS. SREF PLUMES PROGGED A FOCUS OF 1.00 INCH FOR STATE COLLEGE THRU SUN NIGHT...WITH 1-1.5 TOWARDS MASON-DIXON LINE...HOWEVER THIS APPEARS TO BE A CONVERGENCE DRIVEN EVENT VS. A CONVECTIVE DRIVEN EVENT. ATTM DUE TO THE LONG DURATION OF THE EVENT...QPF TOTALS SHUD NOT POSE ANY HYDROLOGIC CONCERNS. WILL STILL CLOSELY MONITOR THE THREAT FOR LOCALIZED...TRAINING HEAVY RAIN BANDS/MINOR SMALL STREAM AND POOR DRAINAGE FLOODING... ESPECIALLY ACROSS SCENT PENN DURING THE MIDDAY AND AFTERNOON HOURS SUNDAY. THE PAST FEW RUNS OF THE NAM HAVE PAINTED THE POTENTIAL FOR 1.5 TO 2 INCHES OF RAIN IN A 12 HOUR PERIOD FROM NEAR KAOO...SSE TO KMRB AND KHGR. && .LONG TERM /MONDAY NIGHT THROUGH SATURDAY/... BEST CHC OF RAIN WL SHIFT TO S PA MONDAY. AFTER TUESDAY AFTERNOON...THINK ANY RAIN FROM CUTOFF WOULD BE SOUTH OF C PA. SOME SHOWERS LATE WED INTO THU WITH NEXT FRONT...BUT NOT LOOKING LIKE A STRONG FRONT...BEST CHC FOR SHOWERS WILL BE WESTERN SECTIONS. CHC OF SHOWERS FOR NEXT FRIDAY...BUT A WAYS OUT...SOME TIMING CONCERNS WITH THAT FRONT. FOR NOW...JUST WENT WITH A CHC... MAINLY THE GMOS WITH SOME MINOR ADJUSTMENTS. TEMPS WILL BE ABOVE NORMAL FOR THE MOST PART INTO LATE NEXT WEEK...BUT CLDS ON SUNDAY INTO MONDAY WILL HOLD DOWN TEMPS CLOSER TO NORMAL. && .AVIATION /06Z SUNDAY THROUGH THURSDAY/... GRADUAL INCREASE IN MOISTURE AND RAIN SHOWERS WILL MEAN A GRADUAL DECREASE IN FLIGHT CONDITIONS OVER THE NEXT 6-12 HOURS. EXPECTED ALL STATIONS TO BE IFR/MVFR BY MORNING...WITH PROBABLY A SLOW LIFT BACK UP TO MVFR BY AFTERNOON. BUT THE SLOW MOVING UPPER LOW WILL KEEP LESS THAN VFR WEATHER IN THE AREA INTO MONDAY AT LEAST. DRIER AIR SHUD BUILD IN LATER MON-TUES...BUT THE CEILINGS MAY BE STUBBORN TO GO AWAY AS WE WILL SEE A DEEP EASTERLY FLOW DEVELOP THRU MID WEEK. IT ALL POINTS TO ONLY SLOW CHANGES FOR THE NEXT SEVERAL DAYS...BUT UNFORTUNATELY...ONCE THINGS DETERIORATE...THEY COULD STAY THAT WAY FOR A WHILE. && .CTP WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...LAMBERT/BEACHLER NEAR TERM...LAMBERT/BEACHLER SHORT TERM...LAMBERT/BEACHLER LONG TERM...BEACHLER/MARTIN AVIATION...LACORTE/GARTNER pa AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY NATIONAL WEATHER SERVICE RAPID CITY SD 849 PM MDT SUN APR 20 2008 .DISCUSSION...COLD FRONT THROUGH JUST ABOUT THROUGH FORECAST AREA...CURRENTLY LOCATED JUST WEST OF A KMBG-KPIR-KICR LINE. GUSTY NORTHWEST WINDS AND RAPIDLY FALLING TEMPERATURES BEHIND THE FRONT. WINDS HAVE BRIEFLY REACHED LOW END ADVISORY AS STRONGEST PRESSURE RISES MOVE THROUGH...BUT ARE STARTING TO DECREASE. A FEW POST FRONTAL SHOWERS HAVE DEVELOPED ACROSS NORTHWEST SOUTH DAKOTA...OTHERWISE DRY CONDITIONS. LATEST WRF/RUC MOVE SHOWERS EASTWARD REST OF THE EVENING...WITH DRY CONDITIONS EXPECTED AFTER MIDNIGHT. FORECAST UPDATED TO ADJUST WINDS/TEMPS BASED ON LOCATION OF COLD FRONT...AND TO LOWER POPS ACROSS SOUTHERN PORTIONS OF FORECAST AREA. && .AVIATION...MVFR/LCL IFR CIGS EXPECTED TO PERSIST ACROSS NORTHEAST WYOMING OVERNIGHT...WITH LOWER CIGS PUSHING INTO NW SD OVERNIGHT. GUSTY NW WINDS AT KRAP WILL DIMINISH THROUGH 05Z. && .PREV DISCUSSION... /ISSUED 220 PM MDT SUN APR 20 2008/ DISCUSSION...UPPER LEVEL LOW CENTERED OVER THE PACIFIC NORTHWEST WITH A SURFACE LOW CENTERED OVER WYOMING. WAVE MOVING THROUGH CENTRAL WYOMING SPARKING SOME CONVECTION AHEAD OF IT. COLD FRONT HAS PUSHED THROUGH NORTHWESTERN SOUTH DAKOTA WHICH HAS SHIFTED THE WINDS TO THE NORTHWEST. TEMPS BEHIND THE FRONT ARE IN THE 40S AND 50S. WITH THE COOLER AIR MOVING IN TODAY...TEMPS SHOULD BE BELOW AVERAGE THROUGH THE MIDDLE OF THE WEEK. HAVE LEFT POPS ALONE FOR THIS EVENING WITH THE WAVE MOVING THROUGH WYOMING. WILL SHIFT THE MENTION OF THUNDERSTORMS FARTHER EAST AHEAD OF THE FRONT WHERE THE BEST INSTABILITY AND SHEAR SHOULD DEVELOP AND LEAVE SHOWERS BEHIND THE FRONT. SHOWERS SHOULD MIX OR CHANGE TO SNOW ACROSS WYOMING AND INTO WESTERN SOUTH DAKOTA LATER THIS AFTERNOON INTO THIS EVENING. DRIER AIR WILL FILTER IN TONIGHT ALLOWING PRECIP TO DISSIPATE IN THE EARLY MORNING HOURS MONDAY. WINDS ARE DECREASING IN SPEED AT KICR AND KVTN BUT STILL EXCEEDING ADVISORY CRITERIA AT K9V9 SO IT WOULD APPEAR THAT THE STRONGER WINDS ARE SHIFTING EASTWARD WITH THE BETTER PRESSURE GRADIENT...SO WILL CANCEL THE WIND ADVISORY EARLY FOR SOUTH CENTRAL. UPPER LEVEL LOW SHIFTS NORTH INTO CANADA MONDAY AS THE NEXT SHORTWAVE MOVES THROUGH LATE MONDAY NIGHT EARLY TUESDAY BRINGING THE NEXT CHANCE FOR PRECIP. MODELS SHIFTING THIS SYSTEM A LITTLE FARTHER NORTH SO TRENDED THAT WAY WITH THE POPS. EXTENDED...UPPER RIDGE AXIS WILL SHIFT QUICKLY EAST ON WEDNESDAY WITH LEE TROF ADVANCING INTO THE HIGH PLAINS. THIS WILL LEAD TO A CHANCE OF AFTN TSTMS ACRS NE WY...SW SD AND THE BLACK HILLS...SO WILL CONTINUE WITH LOW POPS. THERMAL RIDGE OVERHEAD SHOULD LEAD TO A WARM DAY...AND HAVE AGAIN TRENDED TEMPS UPWARD. STRONG UPR TROF WILL THEN MOVE SLOWLY EWD ACROSS THE NRN PLAINS THROUGH THU NIGHT...LEADING TO A CONTINUED CHC FOR PCPN ALONG WITH COOLING TEMPS. A COUPLE OF SHORTWAVES PASSING BY TO THE NORTH WILL BRING A SLIGHT CHANCE OF RAIN ACROSS PORTIONS OF NORTHEASTERN WYOMING AND NORTHWESTERN SOUTH DAKOTA...FROM FRIDAY THROUGH SATURDAY...WITH TEMPS WARMING TO NEAR NORMAL FOR THE BEGINNING OF THE WEEKEND. && .UNR WATCHES/WARNINGS/ADVISORIES... SD...NONE. WY...NONE. && $$ sd AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE ABERDEEN SD 915 PM CDT SUN APR 20 2008 .UPDATE... NO MAJOR UPDATES MADE TO THE FORECAST AT THIS TIME. NEW AVIATION DISCUSSION BELOW. && .PREV DISCUSSION... .SHORT TERM...TONIGHT THROUGH TUESDAY NIGHT DECIDED TO CANCEL THE RED FLAG WARNING AS RH VALUES ARE JUST TOO HIGH TO LET IT REMAIN IN PLACE. DEWPOINTS HAVE STAYED UP AROUND 40 DEGREES WHICH GIVES RH VALUES FROM 35 TO 45 PERCENT ACROSS CENTRAL SOUTH DAKOTA. THE STRONG WINDS AND DRY FUELS THOUGH WILL ALLOW FOR VERY HIGH TO EXTREME FIRE DANGER TO REMAIN INTO THE EVENING HOURS. AS FOR THE WIND ADVISORY...CENTRAL SOUTH DAKOTA HAS BEEN IN CRITERIA OFF AND ON ALL DAY SO WILL LET THE HEADLINE GO THROUGH 00Z THIS EVENING. FOR THE AREAS IN THE JAMES VALLEY AND POINTS EAST WITHIN THE WIND ADVISORY...HAVE ALREADY CUT BACK STOP TIME TO 00Z AND WILL MAKE A LAST MINUTE DECISION WHETHER OR NOT TO CANCEL IT ENTIRELY AS THE EAST HAS NOT REALLY MADE IT TO CRITERIA TODAY. ALTHOUGH 850 MB WINDS DO INCREASE SLIGHTLY OVER THE NEXT FEW HOURS ACCORDING TO RUC. WILL MAKE A LAST MINUTE ANALYSIS BEFORE ZONE ISSUANCE. LOW CLOUDS STILL HANGING IN TOUGH ACROSS THE FAR NORTHEASTERN CWA...EAST OF THE SISSETON HILLS WILL EASTERLY FLOW HAS ALLOWED FOR MOISTURE POOLING. ALTHOUGH AS THE LATE AFTERNOON PROGRESSES INTO EVENING...STILL EXPECTING THESE CLOUDS TO SCATTER OUT. COLD FRONT HAS NOT MOVED MUCH TODAY AND REMAINS IN PLACE ACROSS THE EXTREME WESTERN DAKOTAS. MODELS HAVE SLOWED DOWN THE FRONT AND WILL APPROACH CORSON/DEWEY COUNTIES AROUND 03Z OR SO. HI RES MODELS/REFLECTIVITY SIMULATIONS/SREF DATA STILL SHOWING ISO CONVECTION DEVELOPING LATER THIS EVENING CROSS WESTERN SOUTH DAKOTA...MOVING EAST INTO THE CENTRAL PART OF THE STATE. HAVE ALTERED POPS SLIGHTLY TO REFLECT SLOWER FRONTAL PASSAGE. CAPE VALUES AROUND 500 J/KG DEVELOP ACROSS WESTERN SOUTH DAKOTA THIS EVENING AS LIS DROP JUST BELOW ZERO. AS LAPSE RATES STEEPEN SHOULD BE ENOUGH MINIMAL INSTABILITY TO SPARK ISO/SCT CONVECTION. EXPECTING SOME OF THIS ACTIVITY TO MOVE EASTWARD ACROSS THE CWA OVERNIGHT. FRONT CLEARS THE AREA FOR THE MOST PART BY 18Z TOMORROW SO HAVE TRENDED POPS DOWNWARD A BIT AFTER 18Z. A WEAK WAVE MOVES NORTHEAST ACROSS THE AREA ON TUESDAY BUT NOT LOOKING TO IMPRESSIVE. REDUCED POPS DOWN TO 15 PERCENT AS MOST ISOLATED ACTIVITY LOOKS TO BE ACROSS NORTH CENTRAL SOUTH DAKOTA AND INTO NORTH DAKOTA. .LONG TERM...WEDNESDAY THROUGH SUNDAY MEDIUM RANGE MODELS ARE IN SOME AGREEMENT WITH THE EXTENDED FORECAST PERIOD AT LEAST IN THE NEAR TERM. BY LATE IN THE PERIOD A FAIR AMOUNT OF UNCERTAINTY IS APPARENT IN ENSEMBLE SPREADS. STAYED WITH THE IDEA OF THE WESTERN UNITED STATES UPPER LEVEL H5 LOW WEAKENING AND MOVING EAST. AT THE SURFACE A LOW PRESSURE SYSTEM MOVES OFF OF THE ROCKIES AND MOVES ONTO THE PLAINS THURSDAY. KEPT WITH THE GOING THUNDERSTORM FORECAST AS A GOOD MOISTURE FEED SETS UP AHEAD OF THE LOW. FRIDAY THE REGION WILL BE BETWEEN SYSTEMS AS THE MAIN SURFACE SYSTEM MOVES TOWARD THE EAST COAST. STILL A FAIR AMOUNT OF ENERGY REMAINS IN THE UPPER LEVEL H5 FLOW WITH A TROUGH MOVING EAST OF THIS AREA AND ANOTHER ONE MOVING INTO MONTANA. THIS SYSTEM MOVES THROUGH THE AREA ON THE WEEK END WITH SOME SLIGHT CHANCE OF RAIN SHOWERS. THE BEST CHANCE APPEARS TO BE NORTH OF THIS AREA BUT DID RUN A SLIGHT CHANCE ACROSS MUCH OF THE NORTHERN TIER OF THIS AREA. TEMPERATURES WERE NOT CHANGED MUCH. NEAR SEASONAL NORMALS WILL PREVAIL WHICH WAS WHAT WAS IN THE GOING GRIDS. && .AVIATION... SKIES WILL BE MOSTLY CLEAR TO PARTLY CLOUDY THROUGH THE REMAINDER OF THE EVENING HOURS...WITH JUST SOME HIGH TO MID LEVEL CLOUDS AOA 7K FEET TRACKING ACROSS THE AREA. THERE IS A CHANCE FOR SOME SHOWER ACTIVITY DURING THE OVERNIGHT HOURS...AND AN ISOLATED THUNDERSTORM IS NOT OUT OF THE QUESTION...ESPECIALLY ACROSS THE NORTHWEST AND NORTH CENTRAL PART OF THE CWA. SHOULD ANY PRECIPITATION DEVELOP...CIGS WITH THE PRECIPITATION AREAS WILL NOT FALL BELOW 5K FEET. && .ABR WATCHES/WARNINGS/ADVISORIES... SD...NONE. MN...NONE. && $$ UPDATE...PARKIN SHORT TERM...TMT LONG TERM...KEEFE AVIATION...PARKIN WEATHER.GOV/ABERDEEN sd AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE ABERDEEN SD 723 PM CDT SUN APR 20 2008 .UPDATE... UPDATED DUE TO EXPIRATION OF WIND ADVISORY. && .PREV DISCUSSION... .SHORT TERM...TONIGHT THROUGH TUESDAY NIGHT DECIDED TO CANCEL THE RED FLAG WARNING AS RH VALUES ARE JUST TOO HIGH TO LET IT REMAIN IN PLACE. DEWPOINTS HAVE STAYED UP AROUND 40 DEGREES WHICH GIVES RH VALUES FROM 35 TO 45 PERCENT ACROSS CENTRAL SOUTH DAKOTA. THE STRONG WINDS AND DRY FUELS THOUGH WILL ALLOW FOR VERY HIGH TO EXTREME FIRE DANGER TO REMAIN INTO THE EVENING HOURS. AS FOR THE WIND ADVISORY...CENTRAL SOUTH DAKOTA HAS BEEN IN CRITERIA OFF AND ON ALL DAY SO WILL LET THE HEADLINE GO THROUGH 00Z THIS EVENING. FOR THE AREAS IN THE JAMES VALLEY AND POINTS EAST WITHIN THE WIND ADVISORY...HAVE ALREADY CUT BACK STOP TIME TO 00Z AND WILL MAKE A LAST MINUTE DECISION WHETHER OR NOT TO CANCEL IT ENTIRELY AS THE EAST HAS NOT REALLY MADE IT TO CRITERIA TODAY. ALTHOUGH 850 MB WINDS DO INCREASE SLIGHTLY OVER THE NEXT FEW HOURS ACCORDING TO RUC. WILL MAKE A LAST MINUTE ANALYSIS BEFORE ZONE ISSUANCE. LOW CLOUDS STILL HANGING IN TOUGH ACROSS THE FAR NORTHEASTERN CWA...EAST OF THE SISSETON HILLS WILL EASTERLY FLOW HAS ALLOWED FOR MOISTURE POOLING. ALTHOUGH AS THE LATE AFTERNOON PROGRESSES INTO EVENING...STILL EXPECTING THESE CLOUDS TO SCATTER OUT. COLD FRONT HAS NOT MOVED MUCH TODAY AND REMAINS IN PLACE ACROSS THE EXTREME WESTERN DAKOTAS. MODELS HAVE SLOWED DOWN THE FRONT AND WILL APPROACH CORSON/DEWEY COUNTIES AROUND 03Z OR SO. HI RES MODELS/REFLECTIVITY SIMULATIONS/SREF DATA STILL SHOWING ISO CONVECTION DEVELOPING LATER THIS EVENING CROSS WESTERN SOUTH DAKOTA...MOVING EAST INTO THE CENTRAL PART OF THE STATE. HAVE ALTERED POPS SLIGHTLY TO REFLECT SLOWER FRONTAL PASSAGE. CAPE VALUES AROUND 500 J/KG DEVELOP ACROSS WESTERN SOUTH DAKOTA THIS EVENING AS LIS DROP JUST BELOW ZERO. AS LAPSE RATES STEEPEN SHOULD BE ENOUGH MINIMAL INSTABILITY TO SPARK ISO/SCT CONVECTION. EXPECTING SOME OF THIS ACTIVITY TO MOVE EASTWARD ACROSS THE CWA OVERNIGHT. FRONT CLEARS THE AREA FOR THE MOST PART BY 18Z TOMORROW SO HAVE TRENDED POPS DOWNWARD A BIT AFTER 18Z. A WEAK WAVE MOVES NORTHEAST ACROSS THE AREA ON TUESDAY BUT NOT LOOKING TO IMPRESSIVE. REDUCED POPS DOWN TO 15 PERCENT AS MOST ISOLATED ACTIVITY LOOKS TO BE ACROSS NORTH CENTRAL SOUTH DAKOTA AND INTO NORTH DAKOTA. .LONG TERM...WEDNESDAY THROUGH SUNDAY MEDIUM RANGE MODELS ARE IN SOME AGREEMENT WITH THE EXTENDED FORECAST PERIOD AT LEAST IN THE NEAR TERM. BY LATE IN THE PERIOD A FAIR AMOUNT OF UNCERTAINTY IS APPARENT IN ENSEMBLE SPREADS. STAYED WITH THE IDEA OF THE WESTERN UNITED STATES UPPER LEVEL H5 LOW WEAKENING AND MOVING EAST. AT THE SURFACE A LOW PRESSURE SYSTEM MOVES OFF OF THE ROCKIES AND MOVES ONTO THE PLAINS THURSDAY. KEPT WITH THE GOING THUNDERSTORM FORECAST AS A GOOD MOISTURE FEED SETS UP AHEAD OF THE LOW. FRIDAY THE REGION WILL BE BETWEEN SYSTEMS AS THE MAIN SURFACE SYSTEM MOVES TOWARD THE EAST COAST. STILL A FAIR AMOUNT OF ENERGY REMAINS IN THE UPPER LEVEL H5 FLOW WITH A TROUGH MOVING EAST OF THIS AREA AND ANOTHER ONE MOVING INTO MONTANA. THIS SYSTEM MOVES THROUGH THE AREA ON THE WEEK END WITH SOME SLIGHT CHANCE OF RAIN SHOWERS. THE BEST CHANCE APPEARS TO BE NORTH OF THIS AREA BUT DID RUN A SLIGHT CHANCE ACROSS MUCH OF THE NORTHERN TIER OF THIS AREA. TEMPERATURES WERE NOT CHANGED MUCH. NEAR SEASONAL NORMALS WILL PREVAIL WHICH WAS WHAT WAS IN THE GOING GRIDS. && .AVIATION... LOW STRATUS AND FOG IS IN PLACE ALONG AND EAST OF THE SISSETON HILLS. VISIBLE SATELLITE PICTURE SHOWS IT WILL BE SLOW TO ERODE AS FLOW CONTINUES INTO THE HILLS. SOME CONVECTIVE POTENTIAL EXISTS THIS AFTERNOON AND THIS EVENING ESPECIALLY IN THE CENTRAL PART OF SOUTH DAKOTA. A LOW PRESSURE SYSTEM AND COLD FRONT WILL MOVE ACROSS THE STATE THIS EVENING AND TONIGHT. HAVE A MENTION OF CUMULONIMBUS CLOUDS IN TAFS IN CENTRAL SOUTH DAKOTA. WILL MONITOR DEVELOPMENT OF AFTERNOON CONVECTIVE POTENTIAL. WIND WILL CONTINUE TO BE A CONCERN THIS AFTERNOON INTO EARLY EVENING AS STRONG SOUTH EAST FLOW CONTINUES AHEAD OF FRONTAL SYSTEM. && .ABR WATCHES/WARNINGS/ADVISORIES... SD...NONE. MN...NONE. && $$ UPDATE...PARKIN SHORT TERM...TMT LONG TERM...KEEFE AVIATION...KEEFE WEATHER.GOV/ABERDEEN sd AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE ABERDEEN SD 348 PM CDT SUN APR 20 2008 .SHORT TERM...TONIGHT THROUGH TUESDAY NIGHT DECIDED TO CANCEL THE RED FLAG WARNING AS RH VALUES ARE JUST TOO HIGH TO LET IT REMAIN IN PLACE. DEWPOINTS HAVE STAYED UP AROUND 40 DEGREES WHICH GIVES RH VALUES FROM 35 TO 45 PERCENT ACROSS CENTRAL SOUTH DAKOTA. THE STRONG WINDS AND DRY FUELS THOUGH WILL ALLOW FOR VERY HIGH TO EXTREME FIRE DANGER TO REMAIN INTO THE EVENING HOURS. AS FOR THE WIND ADVISORY...CENTRAL SOUTH DAKOTA HAS BEEN IN CRITERIA OFF AND ON ALL DAY SO WILL LET THE HEADLINE GO THROUGH 00Z THIS EVENING. FOR THE AREAS IN THE JAMES VALLEY AND POINTS EAST WITHIN THE WIND ADVISORY...HAVE ALREADY CUT BACK STOP TIME TO 00Z AND WILL MAKE A LAST MINUTE DECISION WHETHER OR NOT TO CANCEL IT ENTIRELY AS THE EAST HAS NOT REALLY MADE IT TO CRITERIA TODAY. ALTHOUGH 850 MB WINDS DO INCREASE SLIGHTLY OVER THE NEXT FEW HOURS ACCORDING TO RUC. WILL MAKE A LAST MINUTE ANALYSIS BEFORE ZONE ISSUANCE. LOW CLOUDS STILL HANGING IN TOUGH ACROSS THE FAR NORTHEASTERN CWA...EAST OF THE SISSETON HILLS WILL EASTERLY FLOW HAS ALLOWED FOR MOISTURE POOLING. ALTHOUGH AS THE LATE AFTERNOON PROGRESSES INTO EVENING...STILL EXPECTING THESE CLOUDS TO SCATTER OUT. COLD FRONT HAS NOT MOVED MUCH TODAY AND REMAINS IN PLACE ACROSS THE EXTREME WESTERN DAKOTAS. MODELS HAVE SLOWED DOWN THE FRONT AND WILL APPROACH CORSON/DEWEY COUNTIES AROUND 03Z OR SO. HI RES MODELS/REFLECTIVITY SIMULATIONS/SREF DATA STILL SHOWING ISO CONVECTION DEVELOPING LATER THIS EVENING CROSS WESTERN SOUTH DAKOTA...MOVING EAST INTO THE CENTRAL PART OF THE STATE. HAVE ALTERED POPS SLIGHTLY TO REFLECT SLOWER FRONTAL PASSAGE. CAPE VALUES AROUND 500 J/KG DEVELOP ACROSS WESTERN SOUTH DAKOTA THIS EVENING AS LIS DROP JUST BELOW ZERO. AS LAPSE RATES STEEPEN SHOULD BE ENOUGH MINIMAL INSTABILITY TO SPARK ISO/SCT CONVECTION. EXPECTING SOME OF THIS ACTIVITY TO MOVE EASTWARD ACROSS THE CWA OVERNIGHT. FRONT CLEARS THE AREA FOR THE MOST PART BY 18Z TOMORROW SO HAVE TRENDED POPS DOWNWARD A BIT AFTER 18Z. A WEAK WAVE MOVES NORTHEAST ACROSS THE AREA ON TUESDAY BUT NOT LOOKING TO IMPRESSIVE. REDUCED POPS DOWN TO 15 PERCENT AS MOST ISOLATED ACTIVITY LOOKS TO BE ACROSS NORTH CENTRAL SOUTH DAKOTA AND INTO NORTH DAKOTA. .LONG TERM...WEDNESDAY NIGHT THROUGH SUNDAY MEDIUM RANGE MODELS ARE IN SOME AGREEMENT WITH THE EXTENDED FORECAST PERIOD AT LEAST IN THE NEAR TERM. BY LATE IN THE PERIOD A FAIR AMOUNT OF UNCERTAINTY IS APPARENT IN ENSEMBLE SPREADS. STAYED WITH THE IDEA OF THE WESTERN UNITED STATES UPPER LEVEL H5 LOW WEAKENING AND MOVING EAST. AT THE SURFACE A LOW PRESSURE SYSTEM MOVES OFF OF THE ROCKIES AND MOVES ONTO THE PLAINS THURSDAY. KEPT WITH THE GOING THUNDERSTORM FORECAST AS A GOOD MOISTURE FEED SETS UP AHEAD OF THE LOW. FRIDAY THE REGION WILL BE BETWEEN SYSTEMS AS THE MAIN SURFACE SYSTEM MOVES TOWARD THE EAST COAST. STILL A FAIR AMOUNT OF ENERGY REMAINS IN THE UPPER LEVEL H5 FLOW WITH A TROUGH MOVING EAST OF THIS AREA AND ANOTHER ONE MOVING INTO MONTANA. THIS SYSTEM MOVES THROUGH THE AREA ON THE WEEK END WITH SOME SLIGHT CHANCE OF RAIN SHOWERS. THE BEST CHANCE APPEARS TO BE NORTH OF THIS AREA BUT DID RUN A SLIGHT CHANCE ACROSS MUCH OF THE NORTHERN TIER OF THIS AREA. TEMPERATURES WERE NOT CHANGED MUCH. NEAR SEASONAL NORMALS WILL PREVAIL WHICH WAS WHAT WAS IN THE GOING GRIDS. && .AVIATION... LOW STRATUS AND FOG IS IN PLACE ALONG AND EAST OF THE SISSETON HILLS. VISIBLE SATELLITE PICTURE SHOWS IT WILL BE SLOW TO ERODE AS FLOW CONTINUES INTO THE HILLS. SOME CONVECTIVE POTENTIAL EXISTS THIS AFTERNOON AND THIS EVENING ESPECIALLY IN THE CENTRAL PART OF SOUTH DAKOTA. A LOW PRESSURE SYSTEM AND COLD FRONT WILL MOVE ACROSS THE STATE THIS EVENING AND TONIGHT. HAVE A MENTION OF CUMULONIMBUS CLOUDS IN TAFS IN CENTRAL SOUTH DAKOTA. WILL MONITOR DEVELOPMENT OF AFTERNOON CONVECTIVE POTENTIAL. WIND WILL CONTINUE TO BE A CONCERN THIS AFTERNOON INTO EARLY EVENING AS STRONG SOUTH EAST FLOW CONTINUES AHEAD OF FRONTAL SYSTEM. && .ABR WATCHES/WARNINGS/ADVISORIES... SD...WIND ADVISORY UNTIL 7 PM CDT /6 PM MDT/ THIS EVENING FOR BUFFALO- CAMPBELL-CORSON-DEWEY-EDMUNDS-FAULK-HAND-HUGHES-HYDE-JONES- LYMAN-MCPHERSON-POTTER-STANLEY-SULLY-WALWORTH. MN...NONE. && $$ SHORT TERM...TMT LONG TERM...KEEFE AVIATION...KEEFE WEATHER.GOV/ABERDEEN sd AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE ABERDEEN SD 1204 PM CDT SUN APR 20 2008 .UPDATE...REST OF TODAY LOW CLOUDS HAVE ERODED NICELY IN AND AROUND THE JAMES RIVER VALLEY BUT LOW CLOUDS PERSISTING IN THE SISSETON HILLS AND POINTS EAST. LATEST VIS SATELLITE IMAGERY SHOWING A THINNING AND CONTINUED EROSION FROM WEST TO EAST OVER THIS AREA SO EXPECT A GRADUAL CLEARING THROUGH THE AFTERNOON. THESE CLOUDS WILL MAKE FORECAST HIGHS A CHALLENGE ACROSS THE EAST. HAVE SO FAR BROUGHT HIGHS DOWN A COUPLE DEGREES AS ETH/VVV/8D3 STILL IN THE MID/UPPER 40S AT THIS TIME. FEEL THAT ONCE CLOUDS BEGIN TO ERODE THIS AFTERNOON TEMPS WILL RISE NICELY UNDER STRONG APRIL SUN. WILL HAVE TO MONITOR CLOUD TRENDS THROUGHOUT THE EARLY AFTERNOON FOR POSSIBLE ADDITIONAL UPDATES FOR MAX TEMPS OUT EAST. WILL LET WIND ADVISORY REMAIN IN PLACE FOR THE AFTERNOON AS CENTRAL SD CONTINUES TO SEE LOW END ADVISORY CRITERIA. MBG ALONG WITH A FEW SDSU/RAWS SITES HAVE REPORTED SUSTAINED WINDS IN THE LOW 30S MPH WITH GUSTS CLOSE TO 45 MPH. THESE WINDS WILL TRANSLATE INTO THE EASTERN CWA LATER THIS AFTERNOON. MODELS SHOWING STRONGEST 850/925 MB WINDS RIGHT NOW ACROSS CENTRAL SD AND THESE WINDS WEAKEN A BIT AS THEY MOVE EAST BUT SHOULD STILL BE ABLE TO PULL CLOSE TO ADVISORY LEVEL WINDS. AS FOR THE RED FLAG WARNING...WILL OPT TO KEEP IT IN PLACE AT THIS TIME EVEN THOUGH RH VALUES WILL NOT REACH CRITERIA. DEWPOINTS RIGHT NOW EVEN A BIT HIGHER THAN FORECAST WITH PIR/MBG SITTING AT 43 RIGHT NOW. WITH THE VERY WINDY CONDITIONS IN PLACE...ALONG WITH DRY FUELS AND THE POSSIBILITY FOR CLOUD TO GROUND LIGHTNING STRIKES ACROSS CORSON/DEWEY COUNTIES LATE THIS AFTERNOON/EARLY THIS EVENING...WILL KEEP RED FLAG WARNING GOING. WILL MONITOR THROUGHOUT THE AFTERNOON AND MAY DECIDE TO CANCEL IT WITH THE AFTERNOON FORECAST PACKAGE. LATEST MODEL DATA BEGINNING TO HINT AT CONVECTION OCCURRING AFTER DARK OUT WEST SO CLOUD TO GROUND LIGHTNING MAY NOT BE MUCH OF A FACTOR DURING SUNLIGHT HOURS. COLD FRONT POSITION RIGHT NOW ACROSS EXTREME WESTERN DAKOTAS. BUFFALO AND BOWMAN SHOWED SHARP TEMP DROPS AS FRONT MOVED THROUGH. LATEST NAM/RUC SHOWS VIRTUALLY NO MOVEMENT IN COLD FRONT UNTIL LATER THIS EVENING. && .PREV DISCUSSION... .SHORT TERM...THROUGH TUESDAY MORNING. MULTIPLE WEATHER RELATED ISSUES TO DEAL WITH THIS MORNING. FIRST OFF IS MORNING FOG THAT HAS DRIFTED IN FROM MINNESOTA ON EASTERLY FLOW. THIS WILL PERSIST THROUGH MORNING HOURS BUT IS NOT EXPECTED TO HAVE A SIGNIFICANT IMPACT ON TEMPERATURES TODAY. NEXT ISSUE TO ADDRESS WILL BE MEETING WIND ADVISORY CRITERIA. LOW LEVEL JET AHEAD OF APPROACHING SYSTEM SITUATED ACROSS THE WESTERN CWA...WITH H85 WINDS OF +50KTS. THIS LOW LEVEL JET MAXIMUM WILL BEGIN TO MIX IN WESTERN COUNTIES EARLY...GIVEN BUFKIT PROFILES WITH +45KTS AT 2KFT. DURING THE DAY...JET MAXIMUM MOVES EAST...BUT WILL NOT REACH EASTERNMOST COUNTIES UNTIL VERY LATE IN THE AFTERNOON...SO THIS WONT BE A CWA WIDE EVENT. ADDRESSED ALONG WITH THESE STRONG WINDS IS THE FIRE DANGER FOR TODAY. HAVE ISSUED A RED FLAG WARNING BASED ON WINDS DESPITE MIN RH VALUES IN THE 20 TO 30 PERCENT RANGE...TAKING INTO ACCOUNT THE LACK OF GREEN UP ACROSS CENTRAL/NORTH CENTRAL SD. WILL SEE SEVERAL CHANCES FOR PRECIPITATION AS THIS SYSTEM MOVES ACROSS THE CWA. LATE THIS AFTERNOON...WESTERN COUNTIES COULD SEE A ROGUE THUNDERSTORM...WITH CAPE VALUES UP TO 300J/KG. DRY ATMOSPHERIC PROFILES SUGGEST HIGH BASE...DRY LIGHTNING/STRONG WINDS AS THREATS. THUNDERSTORMS/SHOWERS WILL BECOME MORE WIDESPREAD AS COLD FRONT MOVES ACROSS THE STATE EARLY MONDAY. SHOWERS/THUNDERSTORM THREAT CONTINUES TUESDAY AS WEAK MID LEVEL TROUGH ROTATES AROUND UPPER LOW. .LONG TERM...TUESDAY NIGHT THROUGH SATURDAY 00Z MODELS ARE IN BETTER AGREEMENT THIS MORNING. UPPER TROF ALONG THE WEST COAST PROPAGATES EAST INTO THE CENTRAL CONUS ON THURSDAY. THE GFS IS STRONGER WITH THIS SYSTEM AND ACTUALLY FORMS A CLOSED UPPER LOW OVER NORTH DAKOTA...AS OPPOSED TO THE ECMWF/CANADIAN AND THEIR OPEN AND MORE PROGRESSIVE TROFS. NONETHELESS...IT APPEARS THERE IS A FAIR CHANCE OF PCPN WEDNESDAY NIGHT INTO THURSDAY. STRONG LLJ WILL HELP TRANSPORT LLM QUICKLY NORTH. THE GFS ADVECTS SURFACE DEWPOINTS OF UP TO 60F ALL THE WAY UP INTO THE ABR CWA. HAVE A FEELING THIS IS A BIT OVERDONE...BUT 50F DEWPOINTS CERTAINLY A POSSIBILITY. ALSO BELIEVE THE HIGH GFS DEWPOINTS ARE ADVERSELY AFFECTING ITS STABILITY PROGS. HOWEVER...THAT SAID THE DYNAMICS...AVAILABLE MOISTURE AND MID LEVEL LAPSE RATES ALL SUPPORT THUNDER...AND THUS STRATIFORM PCPN WAS CHANGED OVER TO CONVECTIVE FOR WEDNESDAY NIGHT AND THURSDAY. AHEAD OF THE SYSTEM ON WEDNESDAY AND WEDNESDAY NIGHT...BROUGHT UP TEMPS AND DEWPOINTS A NOTCH TO REFLECT THE LATEST TRENDS IN BOTH THE ECMWF AND GFS. && .AVIATION... LOW STRATUS AND FOG IS IN PLACE ALONG AND EAST OF THE SISSETON HILLS. VISIBLE SATELLITE PICTURE SHOWS IT WILL BE SLOW TO ERODE AS FLOW CONTINUES INTO THE HILLS. SOME CONVECTIVE POTENTIAL EXISTS THIS AFTERNOON AND THIS EVENING ESPECIALLY IN THE CENTRAL PART OF SOUTH DAKOTA. A LOW PRESSURE SYSTEM AND COLD FRONT WILL MOVE ACROSS THE STATE THIS EVENING AND TONIGHT. HAVE A MENTION OF CUMULONIMBUS CLOUDS IN TAFS IN CENTRAL SOUTH DAKOTA. WILL MONITOR DEVELOPMENT OF AFTERNOON CONVECTIVE POTENTIAL. WIND WILL CONTINUE TO BE A CONCERN THIS AFTERNOON INTO EARLY EVENING AS STRONG SOUTH EAST FLOW CONTINUES AHEAD OF FRONTAL SYSTEM. && .FIRE WEATHER... STRONG WINDS...WARM TEMPERATURES...AND LOW HUMIDITY ARE EXPECTED ACROSS MUCH OF SOUTH DAKOTA TODAY. THESE CONDITIONS WILL BE EXACERBATED BY A LACK OF GREENUP ACROSS THE REGION SO FAR THIS SPRING. AN EXTREME FIRE DANGER THREAT WILL EXIST THROUGH THE DAY AND INTO THE EVENING HOURS ACROSS MUCH OF THE STATE. RELATIVE HUMIDITIES ARE EXPECTED TO DROP TO BETWEEN 20 TO 30 PERCENT...AND DESPITE VALUES ABOVE THE RED FLAG CRITERIA...WINDS OF 25 TO 35 MPH WITH GUSTS TO 45 MPH WILL SUPPORT EXTREME FIRE BEHAVIOR. IN ADDITION...THERE IS A VERY LOW CHANCE THAT A THUNDERSTORM OR TWO WILL DEVELOP LATE IN THE AFTERNOON. IF ANY STORMS THAT DO DEVELOP ACROSS CENTRAL/NORTH CENTRAL SD...THESE WILL PRODUCE LITTLE ACTUAL PRECIPITATION. && .ABR WATCHES/WARNINGS/ADVISORIES... SD...RED FLAG WARNING UNTIL 10 PM CDT /9 PM MDT/ THIS EVENING FOR LOWER BAD RIVER-MISSOURI COTEAU-UPPER CHEYENNE-UPPER MISSOURI COTEAU. WIND ADVISORY UNTIL 7 PM CDT /6 PM MDT/ THIS EVENING FOR BUFFALO- CAMPBELL-CORSON-DEWEY-EDMUNDS-FAULK-HAND-HUGHES-HYDE-JONES- LYMAN-MCPHERSON-POTTER-STANLEY-SULLY-WALWORTH. WIND ADVISORY UNTIL 10 PM CDT THIS EVENING FOR BROWN-CLARK-DAY- MARSHALL-ROBERTS-SPINK. MN...NONE. && $$ UPDATE...TMT SHORT TERM...CONNELLY LONG TERM...TDK AVIATION...KEEFE WEATHER.GOV/ABERDEEN sd AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE ABERDEEN SD 1039 AM CDT SAT APR 19 2008 .UPDATE... CURRENT FORECAST ON TRACK. TEMPERATURES WARMING TO FORECAST HIGH STILL ON TRACK. A PLEASANT DAY SHAPING UP. WIND WILL NEED TO BE WATCHED THIS AFTERNOON ESPECIALLY IN THE WEST BUT LATEST RUC SHOWS WIND FORECAST STILL LOOKS GOOD. NO CHANGES WILL BE MADE EXCEPT TO ADJUST RATE OF WARMING. && .PREV DISCUSSION... .SHORT TERM...THROUGH MONDAY MORNING SEVERAL ISSUES THIS FORECAST CYCLE...MAINLY PERTAINING TO FIRE WEATHER. DEW POINTS ACROSS THE REGION ARE IN THE LOW 30S/UPPER 20S...ONLY A FEW DEGREES HIGHER THAN THIS TIME YESTERDAY. WITH SURFACE HIGH MOVING EASTWARD...SOUTHEAST WINDS WILL BEGIN TO TAP SLIGHTLY MORE HUMID AIR OVER THE MIDWEST. THE LAG BETWEEN DEVELOPMENT OF GUSTY SURFACE WINDS AND INCREASED MOISTURE ADVECTION JUST HAPPENS TO BE DURING PEAK HEATING IN CENTRAL/NORTH CENTRAL COUNTIES. THE RESULT WILL BE AN INCREASED GRASSLAND FIRE THREAT. CONTINUE TO SUPPORT DEW POINTS IN FORECAST THAT ARE BELOW MODEL GUIDANCE...WHICH HAS BEEN A TREND FOR MOST OF THE WEEK. GIVEN THAT...HUMIDITY VALUES REMAIN TOO MARGINAL FOR RED FLAG WARNING...AND WILL FORGO ISSUANCE. INCREASED MOISTURE SUNDAY WOULD HELP MITIGATE FIRE WEATHER THREAT...HOWEVER SURFACE WINDS OF +40KTS WILL OFFSET THE HIGHER RH VALUES. H85 TEMPERATURES TODAY TO RANGE BETWEEN +15C TO +6C FROM WEST TO EAST...AND INCREASE TO +18C TO +9C FROM WEST TO EAST TOMORROW. THESE WARMER TEMPERATURES EASILY TRANSLATE TO THE SURFACE AS HIGHS IN THE 70S. WITH A LOW LEVEL JET PRESENT ACROSS THE REGION...THE +50KTS OR SO WILL SUPPORT VERY WARM OVERNIGHT TEMPERATURES TONIGHT. WILL CONTINUE TO ADVERTISE CHANCE POPS AS LAPSE RATES STEEPEN ACROSS WESTERN COUNTIES IN THE LATE AFTERNOON SUNDAY...THOUGH OVERALL MOISTURE REMAINS LIMITED. BETTER CHANCE EARLY MONDAY AS COLD FRONT AND UPPER TROUGH MOVE ACROSS REGION...WILL SEE CAPE VALUES UP TO 500 J/KG AND MARGINALLY NEGATIVE LI VALUES. .LONG TERM...MONDAY THROUGH FRIDAY A SURFACE BOUNDARY WILL PUSH INTO WESTERN MINNESOTA ON MONDAY BEFORE STALLING OUT AND WAITING IN ANTICIPATION OF MORE ENERGY ALOFT FOR MONDAY NIGHT AND TUESDAY. WILL MAINTAIN MENTION OF THUNDER FOR MONDAY MORNING DUE TO ELEVATED INSTABILITY IN VICINITY OF ADVANCING FRONT. BUT FOR LATER IN THE DAY MONDAY THROUGH TUESDAY WILL LEAVE PCPN AS SHOWERS WITH NO THUNDER MENTION AS PROGS SHOW FAIRLY STABLE ATMOSPHERE IN PLACE. THE EMPHASIS FOR PCPN MONDAY NIGHT AND TUESDAY WILL COME FROM A WAVE THAT MOVES OUT OF THE ROCKIES AND ACROSS THE REGION. EVEN A NICE LOOKING JET MAX IS PROGGED BY THE GFS TO CROSS THE REGION. AFTER TUESDAY FORECAST CONFIDENCE WANES DRASTICALLY WITH ECMWF AND GFS AT ODDS ON EVOLUTION OF THE MID LEVEL PATTERN. ECMWF MAINTAINS A BROAD WESTERN AND CENTRAL CONUS TROF...WHILE THE GFS/UKMET INDICATE RIDGING. TEMPERATURES WERE AN AMALGAM OF INHERITED GRIDS/00Z MEX GUIDANCE. && .AVIATION... VFR CONDITIONS ARE EXPECTED THROUGH THE NEXT 24 HOURS WITH ANY CLOUDS GENERALLY ABOVE 10K FEET WITH UNRESTRICTED VSBYS. && .ABR WATCHES/WARNINGS/ADVISORIES... SD...NONE. MN...NONE. && $$ UPDATE...KEEFE SHORT TERM...CONNELLY LONG TERM...TDK AVIATION...TMT WEATHER.GOV/ABERDEEN sd AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE FORT WORTH TX 952 PM CDT SUN APR 20 2008 .UPDATE... SOUTH WINDS BETWEEN 5 TO 15 MPH CONTINUE TO TRANSPORT RICH MOISTURE INTO NORTH TEXAS. DEW POINTS IN THE 60S HAVE REACHED AS FAR NORTH AS THE RED RIVER AND AS FAR WEST AS ABILENE. VERY SHARP MOISTURE DISCONTINUITY IS IN PLACE THIS EVENING OVER WEST TEXAS WITH DEW POINTS WEST OF THE DRYLINE IN THE SINGLE DIGITS. INCREASING LLJ OVERNIGHT WILL FACILITATE STRATUS TOMORROW MORNING. STRATUS ALONG WITH WAA AHEAD OF THE NEXT LOW PRESSURE SYSTEM WILL KEEP OVERNIGHT TEMPS IN THE LOWER TO MID 60S. MODELS STILL BREAK OUT PRECIP IN THE WARM SECTOR TOMORROW AS THE SURFACE LOW APPROACHES...EVEN THOUGH THE CAP WILL BE STRONG EARLY ON. SH/13 && .PREV DISCUSSION... /ISSUED 626 PM CDT SUN APR 20 2008/ AVIATION... 0Z TAF ISSUANCE GFS MOS IS MOST PESSIMISTIC WITH SHOWING IFR CIGS IN THE METROPLEX BY EARLY MORNING. RUC MODEL SOUNDINGS AND MET/FWC MOS KEEP THINGS MVFR. WILL THEREFORE NOT GO AS LOW AS MAV MOS THIS ISSUANCE DUE TO LACK OF AGREEMENT...AND WAIT UNTIL 6Z TRENDS TO DECIDE ON IFR. EXPECT MVFR CIGS TO ARRIVE AROUND 6Z IN THE METROPLEX AND LOWER TO NEAR 1000 FT BY 8-9Z. BASED ON SREF PROBABILITIES AND MODEL FORECASTS HAVE HELD THE MVFR CIGS IN THROUGH EARLY-MID AFTERNOON TOMORROW WITH VFR OCCURRING AT AFW/FTW A 2-3 HOURS BEFORE DFW/DAL. FOR WACO...CONFIDENCE IS HIGHER ON IFR CIGS TONIGHT AND EARLY TOMORROW. OTHERWISE...SOUTH WINDS NEAR 10-15KT WILL PREVAIL. TR.92 DISCUSSION... UNSETTLED WEATHER PATTERN WILL BEGIN TOMORROW AS A BROAD UPPER LEVEL TROUGH CURRENTLY CONSUMING THE WESTERN HALF OF THE UNITED STATES CONTINUES TO SHIFT EAST INTO THE CENTRAL AND NORTHERN PLAINS. A WARM NIGHT IS IN STORE AS WEAK RIDGING AND SOUTHWEST WINDS AT 850 MB COMBINE TO KEEP TEMPERATURES AROUND TEN DEGREES ABOVE NORMAL. WEAK RIDGING WILL CONTINUE INTO MONDAY WITH TEMPERATURES EXPECTED TO BE IN THE LOW 80S ACROSS THE EASTERN HALF WHERE CLOUD COVER WILL PERSIST FOR MUCH OF THE DAY...AND IN THE UPPER 80S IN THE WEST WHERE CLOUDS WILL CLEAR IN THE AFTERNOON AS A DRYLINE MOVES IN. SOME DISCREPANCY EXISTS AS TO HOW FAR WEST THE DRYLINE TOMORROW WILL MIX AND HAVE CHOSEN TO FOLLOW THE NAM/GFS WHICH BRINGS THE DRYLINE INTO OUR WESTERN THIRD TOMORROW AFTERNOON. GOOD INSTABILITY WILL EXIST ACROSS NORTH TEXAS TOMORROW...ESPECIALLY IN THE AREA OF THE DRYLINE BUT A STRONG CAP MAY PREVENT ANY STORMS FROM DEVELOPING. ALSO THERE IS NO INDICATION OF UPPER LEVEL FORCING TO HELP BREAK THE CAP AND THE ATMOSPHERE IS PROGGED TO REMAIN FAIRLY DRY. HOWEVER...FORECAST SOUNDINGS AND A FEW MODELS SUGGEST THE CAP MAY WEAKEN DURING THE AFTERNOON HOURS AND WITH ENOUGH HEATING...AN ELEVATED STORM OR TWO MAY BE ABLE TO DEVELOP. IF A STORM DOES DEVELOP IT HAS GOOD POTENTIAL TO BECOME SEVERE PRODUCING LARGE HAIL AND/OR DAMAGING WINDS. THEREFORE...WILL INCLUDE ISOLATED THUNDERSTORMS TOMORROW AFTERNOON ACROSS THE WESTERN THIRD WITH ONLY A 10 PERCENT POP. WEAK FRONT WILL SLIDE INTO NORTH TEXAS TUESDAY AFTERNOON...STALL ACROSS THE NORTHERN HALF OF NORTH TEXAS...AND THEN RETREAT BACK NORTH ON WEDNESDAY. THIS FRONT WILL BE THE FOCUS FOR SHOWERS AND THUNDERSTORMS TUESDAY AFTERNOON THROUGH WEDNESDAY. RAIN CHANCES DURING THIS TIME FRAME STILL REMAIN AT 20-30 PERCENT. INSTABILITY WILL CONTINUE TO BE FAVORABLE FOR SEVERE WEATHER BUT WITH NO LARGE SCALE FORCING TO HELP STORM DEVELOPMENT...THE SEVERE WEATHER POTENTIAL FOR TUESDAY AFTERNOON REMAINS UNCERTAIN BUT CANNOT RULE OUT AN ISOLATED STORM OR TWO APPROACHING OR REACHING SEVERE LIMITS. BEGINNING WEDNESDAY NIGHT...SEVERAL EMBEDDED UPPER LEVEL DISTURBANCES ARE FORECAST TO MOVE ACROSS NORTH TEXAS AND RAIN CHANCES WILL INCREASE TO 40 PERCENT. THE ECMWF KEEPS THE DISTURBANCES NORTH OF TEXAS AND IF THIS HAPPENS THE BEST RAIN CHANCES MAY STAY UP IN OKLAHOMA...THEREFORE DO NOT WANT TO GO HIGHER WITH POPS AT THIS TIME. THE RAIN WILL COME TO AN END THURSDAY MORNING AS THE DISTURBANCES EXIT THE REGION. SEVERE STORMS MAY BE POSSIBLE DURING THIS TIME FRAME AS WELL. COLD FRONT WILL ARRIVE FRIDAY WITH RAIN CHANCES RETURNING AHEAD OF AND ALONG IT. THIS COLD FRONT WILL HELP TO KNOCK TEMPERATURES BACK DOWN TO NEAR NORMAL. THE WEATHER FOR NOW LOOKS DRY AFTER FRIDAY AS NORTHWEST FLOW SETS UP ACROSS THE REGION WITH NO EMBEDDED SHORTWAVES MOVING OUR WAY. 82/JLD && .PRELIMINARY POINT TEMPS/POPS... DALLAS-FT. WORTH, TX 66 83 68 87 / 10 10 10 10 WACO, TX 64 83 65 87 / 10 10 10 10 PARIS, TX 61 78 66 82 / 10 10 10 20 DENTON, TX 65 84 67 85 / 10 10 10 10 MCKINNEY, TX 64 83 67 85 / 10 10 10 10 DALLAS, TX 68 83 68 87 / 10 10 10 10 TERRELL, TX 65 82 68 85 / 10 10 10 20 CORSICANA, TX 65 81 67 86 / 10 10 10 10 TEMPLE, TX 64 83 66 89 / 10 10 10 10 && .FWD WATCHES/WARNINGS/ADVISORIES... NONE. && $$ 92/13 tx AREA FORECAST DISCUSSION...UPDATED FOR AVIATION NATIONAL WEATHER SERVICE FORT WORTH TX 626 PM CDT SUN APR 20 2008 .AVIATION... 0Z TAF ISSUANCE GFS MOS IS MOST PESSIMISTIC WITH SHOWING IFR CIGS IN THE METROPLEX BY EARLY MORNING. RUC MODEL SOUNDINGS AND MET/FWC MOS KEEP THINGS MVFR. WILL THEREFORE NOT GO AS LOW AS MAV MOS THIS ISSUANCE DUE TO LACK OF AGREEMENT...AND WAIT UNTIL 6Z TRENDS TO DECIDE ON IFR. EXPECT MVFR CIGS TO ARRIVE AROUND 6Z IN THE METROPLEX AND LOWER TO NEAR 1000 FT BY 8-9Z. BASED ON SREF PROBABILITIES AND MODEL FORECASTS HAVE HELD THE MVFR CIGS IN THROUGH EARLY-MID AFTERNOON TOMORROW WITH VFR OCCURRING AT AFW/FTW A 2-3 HOURS BEFORE DFW/DAL. FOR WACO...CONFIDENCE IS HIGHER ON IFR CIGS TONIGHT AND EARLY TOMORROW. OTHERWISE...SOUTH WINDS NEAR 10-15KT WILL PREVAIL. TR.92 && .DISCUSSION... UNSETTLED WEATHER PATTERN WILL BEGIN TOMORROW AS A BROAD UPPER LEVEL TROUGH CURRENTLY CONSUMING THE WESTERN HALF OF THE UNITED STATES CONTINUES TO SHIFT EAST INTO THE CENTRAL AND NORTHERN PLAINS. A WARM NIGHT IS IN STORE AS WEAK RIDGING AND SOUTHWEST WINDS AT 850 MB COMBINE TO KEEP TEMPERATURES AROUND TEN DEGREES ABOVE NORMAL. WEAK RIDGING WILL CONTINUE INTO MONDAY WITH TEMPERATURES EXPECTED TO BE IN THE LOW 80S ACROSS THE EASTERN HALF WHERE CLOUD COVER WILL PERSIST FOR MUCH OF THE DAY...AND IN THE UPPER 80S IN THE WEST WHERE CLOUDS WILL CLEAR IN THE AFTERNOON AS A DRYLINE MOVES IN. SOME DISCREPANCY EXISTS AS TO HOW FAR WEST THE DRYLINE TOMORROW WILL MIX AND HAVE CHOSEN TO FOLLOW THE NAM/GFS WHICH BRINGS THE DRYLINE INTO OUR WESTERN THIRD TOMORROW AFTERNOON. GOOD INSTABILITY WILL EXIST ACROSS NORTH TEXAS TOMORROW...ESPECIALLY IN THE AREA OF THE DRYLINE BUT A STRONG CAP MAY PREVENT ANY STORMS FROM DEVELOPING. ALSO THERE IS NO INDICATION OF UPPER LEVEL FORCING TO HELP BREAK THE CAP AND THE ATMOSPHERE IS PROGGED TO REMAIN FAIRLY DRY. HOWEVER...FORECAST SOUNDINGS AND A FEW MODELS SUGGEST THE CAP MAY WEAKEN DURING THE AFTERNOON HOURS AND WITH ENOUGH HEATING...AN ELEVATED STORM OR TWO MAY BE ABLE TO DEVELOP. IF A STORM DOES DEVELOP IT HAS GOOD POTENTIAL TO BECOME SEVERE PRODUCING LARGE HAIL AND/OR DAMAGING WINDS. THEREFORE...WILL INCLUDE ISOLATED THUNDERSTORMS TOMORROW AFTERNOON ACROSS THE WESTERN THIRD WITH ONLY A 10 PERCENT POP. WEAK FRONT WILL SLIDE INTO NORTH TEXAS TUESDAY AFTERNOON...STALL ACROSS THE NORTHERN HALF OF NORTH TEXAS...AND THEN RETREAT BACK NORTH ON WEDNESDAY. THIS FRONT WILL BE THE FOCUS FOR SHOWERS AND THUNDERSTORMS TUESDAY AFTERNOON THROUGH WEDNESDAY. RAIN CHANCES DURING THIS TIME FRAME STILL REMAIN AT 20-30 PERCENT. INSTABILITY WILL CONTINUE TO BE FAVORABLE FOR SEVERE WEATHER BUT WITH NO LARGE SCALE FORCING TO HELP STORM DEVELOPMENT...THE SEVERE WEATHER POTENTIAL FOR TUESDAY AFTERNOON REMAINS UNCERTAIN BUT CANNOT RULE OUT AN ISOLATED STORM OR TWO APPROACHING OR REACHING SEVERE LIMITS. BEGINNING WEDNESDAY NIGHT...SEVERAL EMBEDDED UPPER LEVEL DISTURBANCES ARE FORECAST TO MOVE ACROSS NORTH TEXAS AND RAIN CHANCES WILL INCREASE TO 40 PERCENT. THE ECMWF KEEPS THE DISTURBANCES NORTH OF TEXAS AND IF THIS HAPPENS THE BEST RAIN CHANCES MAY STAY UP IN OKLAHOMA...THEREFORE DO NOT WANT TO GO HIGHER WITH POPS AT THIS TIME. THE RAIN WILL COME TO AN END THURSDAY MORNING AS THE DISTURBANCES EXIT THE REGION. SEVERE STORMS MAY BE POSSIBLE DURING THIS TIME FRAME AS WELL. COLD FRONT WILL ARRIVE FRIDAY WITH RAIN CHANCES RETURNING AHEAD OF AND ALONG IT. THIS COLD FRONT WILL HELP TO KNOCK TEMPERATURES BACK DOWN TO NEAR NORMAL. THE WEATHER FOR NOW LOOKS DRY AFTER FRIDAY AS NORTHWEST FLOW SETS UP ACROSS THE REGION WITH NO EMBEDDED SHORTWAVES MOVING OUR WAY. 82/JLD && .PRELIMINARY POINT TEMPS/POPS... DALLAS-FT. WORTH, TX 66 83 68 87 67 / 10 10 10 10 20 WACO, TX 64 83 65 87 67 / 10 10 10 10 20 PARIS, TX 62 78 66 82 65 / 10 10 10 20 20 DENTON, TX 65 84 67 85 65 / 10 10 10 10 20 MCKINNEY, TX 64 83 67 85 65 / 10 10 10 10 20 DALLAS, TX 68 83 68 87 68 / 10 10 10 10 20 TERRELL, TX 65 82 68 85 67 / 10 10 10 20 20 CORSICANA, TX 65 81 67 86 67 / 10 10 10 10 20 TEMPLE, TX 64 83 66 89 68 / 10 10 10 10 20 && .FWD WATCHES/WARNINGS/ADVISORIES... NONE. && $$ /82 tx AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LA CROSSE WI 255 PM CDT SAT APR 19 2008 .SHORT TERM...THROUGH TUESDAY NIGHT FORECAST CONCERNS WERE PRIMARILY FOCUSED ON FOG POTENTIAL TONIGHT...THEN RAIN CHANCES MONDAY AFTERNOON INTO TUESDAY. LOW PRESSURE AT THE SURFACE AND ALOFT WAS MOVING SLOWLY ACROSS OHIO VALLEY THIS AFTERNOON. EFFECTS OF THIS SYSTEM MANIFESTED BY CLOUD SHIELD WRAPPING OVER THE UPPER MISSISSIPPI VALLEY. EXCEPT FOR A FEW LINGERING PATCHES OF LIGHT RAIN OR DRIZZLE...PRECIPITATION HAD ENDED. ATMOSPHERE STILL MOIST BENEATH CLOUDS COVER...AS EVIDENCED BY RELATIVELY CLOSE TEMPERATURE/DEW POINT SPREADS. FURTHER UPSTREAM... ANOTHER MID LEVEL CIRCULATION WAS LOCATED OVER PACIFIC NORTHWEST. 19.12Z DETERMINISTIC NCEP AND EUROPEAN MODELS WERE IN GOOD AGREEMENT ON OVERALL SYNOPTIC SCALE FEATURES THROUGH EARLY PART OF THE WEEK. THUS...FORECAST CONFIDENCE WAS HIGH THAT THE FORECAST AREA SHOULD RECEIVE ANOTHER RAINFALL EVENT MONDAY AFTERNOON INTO TUESDAY. ONLY MODEL DIFFERENCES THAT MAY HAVE AN IMPACT ON SENSIBLE WEATHER WOULD BE 850MB TEMPERATURES ON MONDAY. NAM/WRF HAD WARMEST VALUES... WHICH WAS REFLECTED IN HIGHEST VALUES OF THE MOS GUIDANCE SUITE. TONIGHT INTO SUNDAY MORNING...ATMOSPHERE PRIMED FOR FOG DEVELOPMENT DUE TO MOIST BOUNDARY LAYER AND LIGHT WINDS. CAVEAT TO THIS WILL BE CURRENT CLOUD COVER AND WHETHER OR NOT THERE WILL BE SUFFICIENT BREAKS IN THE CLOUDS AND/OR CLEARING TO ALLOW FOR RADIATIONAL COOLING. LATEST RUC...NAM/WRF AND GFS SUGGEST RELATIVELY DRIER AIR SHOULD WRAP WESTWARD INTO THE FORECAST AREA...EXCEPT MOST LOCATIONS WEST OF THE MISSISSIPPI RIVER. AS A RESULT...THERE COULD BE AREAS OF DENSE FOG...ALTHOUGH UNCERTAINTY EXISTS ABOUT HOW WIDESPREAD IT COULD BE. AT THIS TIME...OPTED TO MAINTAIN SPIRIT OF CURRENT DATA BASE. MONDAY INTO TUESDAY...LATEST DATA SUITE SUPPORTED PREVIOUS MODEL TRENDS WITH REGARD TO COLD FRONTAL PASSAGE OCCURRING LATE MONDAY NIGHT INTO THE EARLY MORNING HOURS OF TUESDAY. TONGUE OF SURFACE DEW POINTS IN THE 50S ALONG THE FRONT EXPECTED TO INTERACT WITH LOW LEVEL THETA-E CONVERGENCE...ALONG WITH UPPER LEVEL DIVERGENCE...TO PROVIDE SUFFICIENT FORCING TO TRIGGER CONVECTION. TIMING OF FRONT AND ONSET OF FORCING SUGGESTS RAIN CHANCES BEGIN MONDAY AFTERNOON...WITH RAIN CHANCES INCREASING INTO LIKELY CATEGORY MONDAY NIGHT INTO TUESDAY. WITH RESPECT TO SEVERE WEATHER POTENTIAL...HIGHEST 0-6KM WIND SHEAR VALUES RESIDE IN POST-FRONTAL ENVIRONMENT. MEANWHILE...NARROW AXIS OF 0-3KM CAPE OF 1000-1500J/KG BUILDS WEST OF THE MISSISSIPPI RIVER MONDAY AFTERNOON AND EVENING. PER CURRENT SPC DAY 3 OUTLOOK...SLIGHT RISK OF SEVERE STORMS WAS ACROSS PARTS OF SOUTHEAST MN AND NORTHEAST IOWA. THIS APPEARS REASONABLE...ALTHOUGH HIGHEST THREAT MAY EVEN BE FURTHER WEST IN CLOSER PROXIMITY TO FRONT AND HIGHEST WIND SHEAR. BASED ON NAM/WRF 850MB TEMPERATURE FORECAST AROUND 12C AHEAD OF COLD FRONT ON MONDAY...NAM/WRF MOS GUIDANCE HAD WARMEST MAXIMUM TEMPERATURES COMPARED TO NGM AND GFS DATA SUITE. ACCORDING TO TIME/HEIGHT CROSS SECTIONS AND PLAN VIEW OF RELATIVE HUMIDITY...THERE SHOULD BE SUFFICIENT SOLAR INSOLATION TO ALLOW WARM SECTOR HEATING. THUS...OPTED TO NUDGE MAXIMUM TEMPERATURES UPWARD AREAWIDE MONDAY. .LONG TERM...WEDNESDAY THROUGH SATURDAY PRIMARY FOCUS WAS ON RAIN CHANCES FROM THURSDAY INTO FRIDAY. DETERMINISTIC AND PROBABILISTIC DATA CONTINUED TO SUPPORT A CONSISTENT SIGNAL FOR AN UPPER LEVEL AND SURFACE WAVE TO AFFECT THE UPPER MISSISSIPPI VALLEY. AS A RESULT...ANOTHER RAINFALL EVENT APPEARS TO BE IN STORE FOR THE AREA. CURRENT LOW-END RAIN CHANCES IN THIS TIME FRAME WILL PROBABLY WARRANT AN UPGRADE BASED ON POTENTIALLY STRONG DYNAMICS INTERACTING WITH RICH BOUNDARY LAYER MOISTURE. FOR NOW...NO CHANGES WERE MADE TO THIS PORTION OF THE EXTENDED OUTLOOK. && .AVIATION... FOCUS FOR NEXT 24-30 HOURS WILL BE TREND OF LOW CLOUD AND FOG ACROSS THE AREA. LOW STRATUS ALONG WITH DRIZZLE/FOG IN DEFORMATION AREA ON THE NORTHWEST SIDE OF THE DEPARTING SYSTEM. VISIBLE SATELLITE IMAGERY SHOWING SOME BREAKS WHERE DRY AIR ENTRAINED INTO THE OCCLUSION OVER EASTERN HALF OF WI...AND ALSO BREAKS ON THE WESTERN FRINGE OF THE CLOUD SHIELD OVER MN/IA. MODEL SOLUTIONS SUGGEST MOISTURE TO LINGER OVER THE AREA TONIGHT... AND THIS LOOKING ON TARGET...ESPECIALLY GIVEN ALL OF THE RAIN THAT HAS FALLEN RECENTLY. WOULD EXPECT MAINLY BROKEN CONDITIONS OVER THE EAST...IN THE VFR CATEGORY INITIALLY. BUT EXPECT SOME FOG DEVELOPMENT WHICH COULD MORPH INTO LIFR IN FOG/STRATUS AGAIN. OVER THE WEST...EXPECT AREAS THAT CLEAR JUST AHEAD OF THE SLOWLY ADVANCING RIDGE AXIS...TO SOUP IN WITH FOG AND STRATUS. AREAS THAT STAY UNDER THE THICKER CLOUD COVER MAY ACTUALLY SEE THE HIGHEST VISIBILITY. FOR THE TAF FORECASTS AT 18Z...OPTED TO GO ON THE PESSIMISTIC SIDE...WITH LIFR. THIS IN LINE WITH MOS GUIDANCE. WOULD EXPECT SOME IMPROVEMENT PRIOR TO THE NOON HOUR TOMORROW...SO THE LATER PERIODS OF THE TAFS WILL START SHOWING THIS IMPROVEMENT. && .HYDROLOGY... SIGNIFICANT RAIN IS NOW OVER...BUT NOT BEFORE 3 DAY TOTALS OF 2.5 TO 3 INCHES OVER PARTS OF NORTHEAST IA/WESTERN WI. AS EXPECTED...THIS LONG PERIOD OF LIGHT TO MODERATE RAIN RESULTING IN GOOD RISES FOR AREA CREEKS AND RIVERS. A FEW LOCATIONS HAVE REACHED BANKFULL OR MINOR FLOOD STAGE. UPPER HALF OF THE KICKAPOO BASIN HAS PAST CREST...WITH THE FLOOD WATERS NOW MOVING DOWN STREAM. AT THIS POINT LOOKING LIKE CREST WILL BE JUST BELOW FLOOD STAGE. SAME FOR THE UPPER IOWA RIVER...WITH DORCHESTER THE CLOSEST TO REACHING BANKFULL. MOST SIGNIFICANT RISES WERE ALONG THE TURKEY RIVER...ESPECIALLY FROM ELKADER DOWN THROUGH GARBER. MINOR IN THAT AREA...CRESTING NEAR OR JUST ABOVE FLOOD STAGE. THE BLACK RIVER APPEARS TO BE HAVING THE WORST OF IT...HAVING JUST COME DOWN FROM A SIGNIFICANT RISE LAST WEEK. ANTECEDENT CONDITIONS AND NEW RAIN TOTALS SENDING HATFIELD AND BLACK RIVER FALLS TO THE HIGHEST CRESTS IN A WHILE. THIS WILL TRANSLATE DOWNSTREAM TOWARD GALESVILLE. EXPECT HIGHWAY VV TO BE CLOSED AGAIN ALONG THE LA CROSSE/TREMPEALEAU COUNTY LINE FOR THE NEXT SEVERAL DAYS. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...NONE. MN...NONE. IA...NONE. && $$ SHORT/LONG TERM......THOMPSON AVIATION/HYDROLOGY...MW wi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TALLAHASSEE FL 255 AM EDT MON APR 21 2008 .SYNOPSIS... 06Z WATER VAPOR AND H4 RUC ANALYSIS SHOWING A COMPLEX AND VERY STATIC UPPER LEVEL PATTERN OVER NORTH AMERICA THIS MORNING. MAIN FEATURES OF NOTE FOR OUR FORECAST INCLUDE A SLOW MOVING AND CLOSED UPPER LOW SPINNING OVER THE MID-ATLANTIC STATES AND CAROLINAS. ABUNDANT ATLANTIC MOISTURE BEING DRAWN INTO THE CIRCULATION IS RESULTING IN PLENTY OF SHOWERS/THUNDERSTORMS ACROSS EASTERN PORTIONS OF NORTH CAROLINA AND VIRGINIA. FURTHER UPSTREAM WEAK RIDGING IS PUSHING NORTH FROM THE NORTH-CENTRAL GOMEX OVER THE SOUTHERN AND MIDDLE MISSISSIPPI VALLEY. OUR FORECAST AREA RESIDES BETWEEN THESE TWO SYSTEMS RESULTING IN FAST NORTHWESTERLY FLOW OVERHEAD. EVEN FURTHER TO THE WEST WE FIND A LARGE AND SLOW MOVING UPPER LOW. THE LOW IS CENTERED OVER WASHINGTON AND SOUTHERN BRITISH COLUMBIA BUT HAS INFLUENCE OVER MUCH OF THE WESTERN UNITED STATES AND SOUTHWEST CANADA PROVIDING UNSEASONABLE COOL TEMPERATURES. AT THE SURFACE...LOW PRESSURE ASSOCIATED WITH THE UPPER LOW ACROSS THE MID-ATLANTIC RESIDES ALONG THE CAROLINA COASTLINE. LARGE AREA OF SURFACE RIDGING WRAPS AROUND THIS LOW FROM NEW ENGLAND TO THE OHIO AND TENNESSEE VALLEYS AND THEN SOUTHWARD TO THE CENTRAL AND NORTHEAST GULF COASTS. THIS RIDGE IS PROVIDING A DRY AND SEASONABLE EARLY MORNING WITH TEMPERATURES SLOWLY FALLING THROUGH UPPER 50S AND LOWER 60S INLAND AND THE MIDDLE 60S ALONG THE COAST. AREA OF SCT-BKN HIGH CIRRUS HAS BEEN OVERSPREADING OUR SKIES FROM THE WEST THROUGH THE LAST FEW HOURS WITH PARTLY/MOSTLY CLOUDY SKIES EXPECTED INTO THE FIRST FEW DAYLIGHT HOURS. && .SHORT TERM (TODAY THROUGH WEDNESDAY NIGHT)... PLEASANT AND DRY WEATHER TO BE THE RULE THROUGH THE SHORT TERM AS ANY ACTIVE WEATHER REMAINS WELL TO OUR EAST AND WELL TO OUR WEST. MID/UPPER LEVEL RIDING FROM THE NORTH-CENTRAL GOMEX TO THE WESTERN TENNESSEE/OHIO VALLEYS AND THEN EASTWARD TO THE NORTHEASTERN STATES WILL FORCE THE CLOSE UPPER LOW OVER THE MID-ATLANTIC STATES TO BEGIN SLOWLY PUSHING SOUTHEAST. THE MOVEMENT OF THE UPPER LEVEL FEATURE WILL DRAG THE SURFACE LOW SOUTHEAST AS WELL WITH BOTH EXITING OFF THE CAROLINA COASTLINE THIS EVENING INTO TONIGHT. THE RESULT FOR OUR FORECAST AREA WILL BE LITTLE CHANGE IN WEATHER PATTERN WITH SURFACE RIDING HOLDING IN PLACE AND NORTHWEST FLOW ALOFT. DAY WILL START OUT WITH SOME HIGHER LEVEL CIRRUS (DESCRIBED ABOVE). NAM/GFS INITIALIZED THIS HIGH LEVEL MOISTURE FAIRLY WELL AND BOTH SHOW THE BULK OF THE CIRRUS EXITING DURING THE MID/LATE MORNING HOURS. THE RESULT WILL BE A PARTLY TO MOSTLY SUNNY AFTERNOON WITH JUST A SCT CU FIELD. 850MB TEMPS BETWEEN 10 AND 12C RESULTING IN HIGH TEMPERATURES ONCE AGAIN RISING INTO GENERALLY THE LOWER 80S AWAY FROM THE COAST. WITH SURFACE RIDGING IN PLACE...THE DIURNAL HEATING EXPECTED TO FUEL A FAIRLY DECENT SEA-BREEZE CIRCULATION ALONG THE COAST FOR THE AFTERNOON (10-15 MPH). COOLER AIR IMPORTED OFF THE SHELF WATERS SHOULD ONCE AGAIN HOLD LOCATIONS ALONG THE IMMEDIATE COAST TO THE MIDDLE AND UPPER 70S. WITH LITTLE CHANGE IN EXPECTED WEATHER OR SURFACE PATTERN THE NEXT SEVERAL DAYS WOULD EXPECT HEALTHY SEA-BREEZE CIRCULATIONS AGAIN TUESDAY AND POSSIBLY WEDNESDAY AFTERNOONS KEEPING THE COASTAL AREAS A BIT COOLER. LOW TEMPERATURES TONIGHT GENERALLY IN THE LOWER TO MIDDLE 50S INLAND AND UPPER 50S TO NEAR 60 ALONG THE COAST. UPPER LEVEL AND SURFACE RIDGING FROM NEW ENGLAND TO THE CENTRAL GULF COAST CONTINUES TO FORCE THE UPPER LOW SOUTHEAST TO A POSITION NORTHEAST OF THE BAHAMAS THROUGH TUESDAY NIGHT. WITH THE SYSTEM FURTHER OFFSHORE...MID/UPPER LEVEL HEIGHTS WILL BEGIN TO RISE OVERHEAD. WITH THE SURFACE LOW OFF THE SOUTHEAST COAST...WILL HAVE TO WATCH ANY LOWER LEVEL MOISTURE THROWN BACK TOWARD THE COAST BY THE CIRCULATION THAT COULD RESULT IN SOME AREAS OF LOWER CLOUDS. AT THIS POINT...WOULD EXPECT ANY LOWER CLOUDS TO REMAIN TO OUR EAST...BUT CAN NOT RULE OUT A BIT MORE CLOUD-COVER TUESDAY NIGHT INTO WEDNESDAY MORNING FOR SOUTH-CENTRAL GA AND THE EASTERN FL BIG BEND. UPPER LEVEL RIDGE TO OUR WEST AMPLIFIES AND BEGINS TO MOVE EAST FOR WEDNESDAY. HIGH PRESSURE CENTERED OVER THE MID-ATLANTIC STATES BY THIS TIME WILL CONTINUE TO RIDGING SOUTHWARD TO THE NORTHEAST GULF OF MEXICO. HIGH TEMPERATURES BOTH TUESDAY AND WEDNESDAY SHOULD CHANGE LITTLE WITH LOWER 80S COMMON INLAND AND MIDDLE 70S TO NEAR 80 ALONG THE COAST. LOW TEMPERATURES TUESDAY NIGHT ON THE SEASONABLE SIDE WITH MIDDLE AND UPPER 50S INLAND TO THE LOWER AND MIDDLE 60S ALONG THE COAST. && .LONG TERM (THURSDAY THROUGH MONDAY)...RATHER SHARP UPPER RIDGE WILL BUILD OVER THE DEEP SOUTH FOR THE LATTER PART OF THE WEEK. ASSOCIATED SFC HIGH PRESSURE OVER THE MID ATLANTIC WILL GENERATE EASTERLY FLOW FOR THE AREA THURSDAY AND FRIDAY. NOT EXPECTING ENOUGH MOISTURE FOR SHOWERS...BUT COULD SEE AN INCREASE IN CLOUD COVER OVER FAR EASTERN ZONES. BY FRIDAY...APPROACHING SHORTWAVE WILL BEGIN TO BEAT DOWN THE RIDGE...WITH ENOUGH MOISTURE AVAILABLE OVER THE WESTERN ZONES FOR A COUPLE OF AFTERNOON SHOWERS. EVOLUTION OF THIS APPROACHING SYSTEM IS UNCLEAR ATTM...BUT AT LEAST SLIGHT CHANCE POPS APPEAR PRUDENT FOR SATURDAY AFTERNOON ACROSS THE AREA. MODEL DIFFERENCE MORE APPARENT BY SUNDAY...WITH ECMWF PUSHING COLD FRONT SOUTH OF THE CWA...AND GFS HANGING THE FRONT UP NEAR OF JUST NORTH OF THE AREA. FOR NOW...WILL CONTINUE TO ADVERTISE SLIGHT CHANCE POPS UNTIL MORE OF A CONSENSUS DEVELOPS. TEMPERATURE WISE...EXPECT HIGHS REACHING THE MID 80S THURSDAY AND POSSIBLY FRIDAY WITH THE RIDGE ALOFT. BY THE WEEKEND...INCREASING CLOUDS AND MOISTURE SHOULD HOLD TEMPS IN THE LOWER 80S. OVERALL...SHOULD BE PRETTY CLOSE TO CLIMO. && .AVIATION... WEAK PRESSURE GRADIENT AND BUILDING RIDGE ALOFT WILL YIELD VFR CONDITIONS FOR ALL TERMINALS TODAY INTO TONIGHT. && .MARINE... HIGH PRESSURE WITH A FAIRLY LIGHT GRADIENT IS EXPECTED TO CONTINUE THROUGH WEDNESDAY WITH WINDS AND SEAS REMAINING BELOW HEADLINE CRITERIA. WIND DIRECTIONS WILL BE QUITE VARIABLE THROUGH THE PERIOD DEPENDING ON THE EXACTLY WHERE THE RIDGE AXIS SETS UP. SEA BREEZE CIRCULATIONS SHOULD BE EXPECTED TO DEVELOP THIS AFTERNOON AND AGAIN ON TUESDAY AFTERNOON. THESE CIRCULATIONS WILL RESULT IN A BIT STRONGER ONSHORE FLOW NEAR THE COAST...BUT STILL BELOW HEADLINE CRITERIA. THE RIDGE IS EXPECTED TO TAKE A POSITION BY WEDNESDAY NIGHT INTO FRIDAY THAT MAY BECOME MORE FAVORABLE FOR EASTERLY SURGES OF WIND AT NIGHT. THE FORECAST IS EXPECTED TO REMAIN RAIN FREE THROUGH AT LEAST THURSDAY. && .FIRE WEATHER... HIGH TEMPS IN THE LOWER 80S COMBINED WITH AFTERNOON DEWPOINT IN THE UPPER 40S WILL COMBINE TO PRODUCE SEVERAL HOURS OF CRITICAL RH THIS AFTERNOON OVER INLAND AREAS OF FLORIDA. CURRENT WARNING COVERS THIS WELL. NEAR CARBON COPY EXPECTED ON TUESDAY SO WILL HOIST FIRE WX WATCH FOR THAT TIME PERIOD. && .PRELIMINARY POINT TEMPS/POPS... .PRELIMINARY POINT TEMPS/POPS... TALLAHASSEE 83 50 83 57 82 / 0 0 0 0 0 PANAMA CITY 80 59 80 61 80 / 0 0 0 0 0 DOTHAN 83 54 83 58 82 / 0 0 0 0 0 ALBANY 81 53 83 57 82 / 0 0 0 0 0 VALDOSTA 82 50 82 56 81 / 0 0 0 0 0 CROSS CITY 84 52 83 56 82 / 0 0 0 0 0 && .TAE WATCHES/WARNINGS/ADVISORIES... AL...NONE. GA...NONE. FL...RED FLAG WARNING FROM 2 PM EDT /1 PM CDT/ THIS AFTERNOON TO 7 PM EDT /6 PM CDT/ THIS EVENING FOR THE FOLLOWING ZONES: BAY...CALHOUN...DIXIE...FRANKLIN...GADSDEN...GULF...HOLMES... INLAND WALTON...JACKSON...JEFFERSON...LAFAYETTE...LEON... LIBERTY...MADISON...TAYLOR...WAKULLA...WASHINGTON. FIRE WEATHER WATCH FROM TUESDAY AFTERNOON THROUGH TUESDAY EVENING FOR THE FOLLOWING ZONES: BAY...CALHOUN...DIXIE... FRANKLIN...GADSDEN...GULF...HOLMES...INLAND WALTON... JACKSON...JEFFERSON...LAFAYETTE...LEON...LIBERTY... MADISON...TAYLOR...WAKULLA...WASHINGTON. GM...NONE. && $$ AVIATION/LONG TERM/FIRE WEATHER...CAMP PUBLIC/MARINE...MROCZKA fl AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LOUISVILLE KY 300 AM EDT MON APR 21 2008 .SHORT TERM (TODAY AND TONIGHT)... ONLY WEATHER CONCERNS IN THE SHORT TERM WILL BE FOG THIS MORNING. LOW CLOUDS WILL CONTINUE TO ERODE DURING THE PRE-DAWN HOURS. BOUNDARY LEVEL WINDS ARE QUITE LIGHT AND FROM THE SOUTHEAST. SKIES HAVE ALREADY CLEARED ACROSS THE BLUEGRASS. THE RUC SEEMS TO HAVE LATCHED ON TO THE DEVELOPING FOG AND LOWERS VISIBILITIES QUITE A BIT ACROSS SOUTHERN INDIANA AND CENTRAL KENTUCKY...ESPECIALLY THE BLUEGRASS REGION. WILL MAINTAIN MENTION OF PATCHY DENSE FOG. MAY ISSUE A DENSE FOG ADVISORY SHOULD VISIBILITIES LOWER TO 1/2 MILE OVER A BROAD AREA. UPPER AIR PATTERN IS CURRENTLY QUITE BLOCKY. A CUTOFF UPPER LOW NOW ACROSS THE MID-ATLANTIC WILL SAG SOUTHEASTWARD VERY SLOWLY OVER THE NEXT COUPLE OF DAYS. ACROSS THE PACIFIC NORTHWEST A UNSEASONABLY DEEP AND COLD UPPER LOW WILL REMAIN IN PLACE. AS IS TYPICAL OF CUTOFF LOWS...AREAS AROUND THE DISTURBANCE NOT AFFECTED BY CLOUDINESS WILL EXPERIENCE QUITE MILD WEATHER. THIS WILL BE TRUE FOR THE GREAT LAKES AND NEW ENGLAND TODAY AND TOMORROW. THE CUTOFF LOW TO OUR EAST WILL LOSE ITS INFLUENCE ACROSS THE LOWER OHIO VALLEY TODAY. TEMPERATURES SHOULD WARM NICELY THIS AFTERNOON UNDER MOSTLY SUNNY SKIES. WITH A VIRTUALLY NON-EXISTENT PRESSURE GRADIENT...WINDS WILL BE QUITE LIGHT AND VARIABLE. MOSTLY CLEAR SKIES WILL CONTINUE TONIGHT. PATCHY FOG IS QUITE POSSIBLE AGAIN TOMORROW MORNING. .LONG TERM (MONDAY NIGHT THROUGH SUNDAY)... TUESDAY THROUGH WEDNESDAY NIGHT... A SLOW MOVING COLD FRONT AND WEAK UPPER TROUGH WILL STRUGGLE TO MAKE INROADS INTO AN UPPER LEVEL RIDGE THAT WILL BE BUILDING OVER THE SOUTHEAST UNITED STATES AND THE CWA TUESDAY AND WEDNESDAY. CURRENT MODEL SOLUTIONS CONTINUE PREVIOUS TREND OF SLOWING FRONT DOWN AND PUSHING MAIN ENERGY INTO THE NORTHERN GREAT LAKES TUESDAY NIGHT AND WEDNESDAY...INSTEAD OF BRINGING IT INTO SOUTH CENTRAL INDIANA AND CENTRAL KENTUCKY. PER COORDINATION WITH NEIGHBORING OFFICES HAVE DRIED OUT THE FORECAST FOR TUESDAY NIGHT THROUGH WEDNESDAY NIGHT TO ACCOUNT FOR THIS. LATEST GFS AND NAM MODELS BOTH INDICATING UPPER RIDGE AXIS MAY BE DIRECTLY OVER TOP OF THE CWA LATE WEDNESDAY INTO THURSDAY...WHICH COULD MEAN DRY WEATHER FOR THURSDAY AND BEYOND ALSO. FOR NOW WILL NOT MAKE ANY CHANGES TO THE THURSDAY AND AFTER PERIOD AND MONITOR MODELS AND TRENDS AT A LATER TIME. PREVIOUS FORECAST DISCUSSION FOR THURSDAY THROUGH SUNDAY BELOW. THU THRU SUN... THIS FORECAST LEANS TOWARD THE GFS ENSEMBLES AND HPC WITH ASSISTS FROM THE ECMWF AND CANADIAN ENSEMBLES. CONSENSUS FROM THE ENSEMBLES AND HPC IS THAT A WARM FRONT WILL MOVE THRU OUR FA THU WITH A CDFNT APPROACHING AND MOVING THRU FRI NIGHT. UPR LEVEL TROF IN ARREARS OF FRONT TO APPROACH/MOVE THRU SAT. AT THIS POINT...THE GUIDANCE POINTS AT LATE FRI/FRI NIGHT AS THE BEST CHC FOR WIDESPREAD CONVECTIVE RAINFALL ASSOCIATED WITH FRONTAL APPROACH/PASSAGE. IT IS THIS PERIOD...WHERE WE WILL INSERT HIGHEST CHC POPS. FOR THU AFTN THRU FRI AFTN...WILL LEAVE 20 TO 40% POPS AS WMFNT REACHES UPR OH VLY BY EARLY FRI WITH CDFNT ACRS MO AT THAT TIME...AND MOISTURE TRANSPORT INCREASING ON SLY FLO. DEBATED ABOUT LEAVING SAT DRY PER OUR CURRENT FCST FAVORING THE ECMWF...BUT GENERALLY WENT WITH HPC/GFS ENSEMBLES WITH SMALL CHC POPS FOR POST FRONTAL SHOWERS AHEAD OF AFOREMENTIONED UPR LEVEL TROF. WILL END RAIN CHCS SAT NIGHT AND CONTINUE INTO SUN AS HIGH PRESSURE TRACKS FROM THE MID MS VLY INTO THE WESTERN OH VLY. TEMPS WILL BE WARMEST...ABOVE LATE APR SEASONAL NORMS...ON THU AND FRI WITH WMFROPA AND PRECDFNT. COOLEST TEMPS TO OCCUR SAT AND SUN NIGHT (GENERALLY 40 TO 45) OWING TO COLD ADVECTION SAT NIGHT AND RADIATIONAL COOLING SUN NIGHT AS 850 TEMPS DROP TO 1-5C. && .AVIATION (06Z TAFS)... FOG IS EXPECTED TO DEVELOP TO VARIOUS DEGREES AT ALL TAF SITES OVERNIGHT. SCATTERED STRATO-CU IS SLOWLY ERODING AND SHOULD ALLOW VFR CIGS TO ARRIVE AT SDF BY 08Z. CLOUDS HAVE ALREADY SCATTERED OUT AT LEX AND EXPECT MOSTLY CLEAR SKIES AT BWG OVERNIGHT. WINDS ARE LIGHT...WITH A DISTINCT SUBSIDENCE INVERSION SETTING UP. FOG WILL DEVELOP IN THE 08 TO 10Z TIME FRAME. FOG WILL BE MOST DENSE AT THE TYPICALLY FAVORED LOCATION OF BWG. HOWEVER...OUTSIDE OF URBAN AREAS...WIDESPREAD FOG IS MOST LIKELY ACROSS SOUTHERN INDIANA AND THE NORTHERN BLUEGRASS. VISIBILITIES WILL LOWER TO MVFR AT SDF AND LEX...AND MOST PROBABLY...TO IFR AT BWG. AFTER MORNING FOG DISSIPATES JUST AFTER DAWN...EXPECT MOSTLY CLEAR SKIES AND LIGHT WINDS DURING THE DAY MONDAY. && .LMK WATCHES/WARNINGS/ADVISORIES... KY...NONE. IN...NONE. && $$ SHORT TERM...JSD LONG TERM....MACZKO/13 AVIATION.....JSD ky AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 408 AM EDT MON APR 21 2008 .DISCUSSION... THE MAIN FORECAST CONCERNS WITH THIS FORECAST PACKAGE ARE THE HIGH TEMPERATURES FOR TODAY AND THE CHANCES OF RAIN SHOWERS AND THUNDERSTORMS TONIGHT. WATER VAPOR IMAGERY AND RUC ARE SHOWING A DEEP LOW OVER SOUTHWEST CANADA AND THE NORTHERN ROCKIES EMBEDDED IN A LONGWAVE TROUGH OVER WESTERN CANADA. ANOTHER CLOSED LOW IS OVER THE CAROLINAS...AND A WEAK RIDGE BLANKETS THE GREAT LAKES AND ONTARIO. SURFACE ANALYSIS DEPICTS DEEP LOWS OVER SASKATCHEWAN AND CENTRAL KANSAS...WITH A FRONTAL SYSTEM CONNECTING THE TWO. ALSO A WEAK WARM FRONT EXTENDS ACROSS THE FORECAST AREA FROM THE LOW OVER SASKATCHEWAN. THE MID LEVEL LOW OVER THE NORTHERN ROCKIES WILL DEEPEN OVER SOUTHEASTERN ALBERTA TODAY...WHILE THE ACCOMPANYING SURFACE LOW DEEPENS OVER NORTHERN MANITOBA. THE SURFACE FRONT WILL MOVE INTO EASTERN MINNESOTA. WEAK SHORTWAVES WILL PASS THROUGH THE AREA. 310K ISENTROPIC ANALYSIS DEPICTS ASCENT OVER MINNESOTA AND NORTHERN WISCONSIN BY LATE AFTERNOON. THE AIR MASS WILL CONTINUE TO BE DRY ENOUGH TO PREVENT ANY PRECIPITATION TODAY. FORECAST SOUNDINGS INDICATE THAT THERE SHOULD BE SOME HIGH CLOUDS WITH THE SHORTWAVES...AND A SOME CUMULUS DEVELOPMENT THIS AFTERNOON AROUND 2.5K FEET. THIS SHOULD HOLD DOWN TEMPERATURES JUST A BIT. THE LATEST TRAJECTORY FORECAST SUGGEST THAT THE AIR MASS OVER LOWER MICHIGAN AND SOUTHERN WISCONSIN WILL WORK INTO THIS AREA TODAY. THIS WOULD SUPPORT TEMPERATURES AROUND 70 TODAY FOR THE FORECAST AREA. THE MID LEVEL LOW WILL TREK INTO CENTRAL SASKATCHEWAN TONIGHT. WEAK SHORTWAVE BEING EJECTED OUT AHEAD OF THE LOW WILL SWEEP INTO THE WESTERN U.P. THE SURFACE LOW WILL LIFT INTO NORTHERN SASKATCHEWAN... WHILE THE COLD FRONT SHIFT INTO WESTERN LAKE SUPERIOR. ISENTROPIC ASCENT WILL SHIFT INTO THE WESTERN U.P. INCREASE CLOUD COVER WILL ALSO HELP HOLD THE TEMPERATURES UP. THUS LOOKING FOR TEMPERATURES AROUND 50. THE MID LEVEL LOW WILL LIFT TO NORTHERN SASKATCHEWAN ON TUESDAY. AS THE COLD FRONT SWEEPS ACROSS THE FORECAST AREA...A NARROW AREA OF MUCAPE VALUES OF 300J/KG WILL MOVE WITH THE FRONT. A NARROW BAND OF DEEP MOISTURE ACCOMPANYING THE FRONT ALONG WITH THE ISENTROPIC ASCENT AREA WITH THE FRONTAL SYSTEM TO BRING RAIN SHOWERS AND A CHANCE OF THUNDERSTORMS TO THE AREA. THE MID LEVEL LOW WILL FILL AS IT SLIDES INTO CENTRAL CANADA TUESDAY NIGHT. A STRONG SHORTWAVE TROUGH ROTATING AROUND THE LOW WILL ROTATE THROUGH THE FORECAST AREA. THE COLD FRONT WILL MARCH INTO THE LOWER GREAT LAKES. A SURFACE RIDGE FOLLOWING THE FRONT WILL OVERSPREAD THE FORECAST AREA. ANOTHER COLD FRONT WILL SLIDE OUT THE CANADIAN PRAIRIE AND INTO NORTHWEST MINNESOTA PUSHED ALONG BY A HIGH SETTLING OUT OF THE CANADIAN PRAIRIE. COLD AIR BEHIND THE FRONT WILL CAUSE THE OVERNIGHT LOWS TO DIP INTO THE MID AND UPPER 30S. THE SHORTWAVE ENERGY WILL SLIDE OFF TO THE EAST ON WEDNESDAY. THE HIGH DOMINATING THE AREA WILL KEEP DRY AND LOW LEVEL STABLE CONDITIONS OVER THE AREA. THE NORTHERN END OF THE COLD FRONT OVER MINNESOTA WILL SHIFT INTO CENTRAL ONTARIO. A LOW CENTRER WILL DEVELOP ALONG THE FRONT AND SLIP INTO THE WESTERN DAKOTAS. THE AIR MASS WILL REMAIN DRY OVER THE AREA. A MID LEVEL AND SURFACE RIDGE WILL TRACK ACROSS THE FORECAST AREA WEDNESDAY NIGHT. THE SURFACE LOW WILL MOVE INTO SOUTHEAST NORTH DAKOTA. ISENTROPIC ASCENT WILL PRODUCE RAINS OVER MINNESOTA. THE MID LEVEL RIDGE WILL SHIFT INTO EASTERN ONTARIO. A WEAK SHORTWAVE WILL SHIFT INTO WISCONSIN. A SURFACE LOW WILL MOVE INTO WEST CENTRAL ONTARIO DRAGGING A COLD FRONT INTO THE UPPER MISSISSIPPI RIVER VALLEY. ISENTROPIC ASCENT WILL SPREAD RAINS INTO THE WEST END OF THE FORECAST AREA ON THURSDAY. THE SHORTWAVE AND FRONTAL SYSTEM WILL SLIDE OVER THE AREA. THIS SHOULD BRING RAIN SHOWERS AND A CHANCE OF THUNDERSTORMS TO THE AREA. && .HYDROLOGY (ISSUED AT 345 PM EDT SUN)... AT THE CHOCOLAY RIVER THE LATEST READINGS SHOW A SLIGHT DECREASE IN STAGE SINCE YESTERDAY EVENING. LATEST RFC FORECAST HAS DELAYED THE CREST...WHICH IS 10 FEET...UNTIL WEDNESDAY MORNING. THIS CHANGE IS A DIFFERENCE OF ABOUT 12 HOURS FROM THE PREVIOUS FORECAST. THE STAFF GAUGE NEAR CHASSELL ON THE STURGEON RIVER IS NOW ABOVE 10.5 FEET PER READINGS FROM THE HOUGHTON COUNTY EM. FLOOD WARNING WILL CONTINUE THERE LIKELY THROUGH THE WEEK. LOOKING AT A COUPLE OTHER SITES...BOTH THE STURGEON RIVER NEAR ALSTON AND THE MICHIGAMME RIVER NEAR WITCH LAKE LOOK AS IF THEY WILL REACH FLOOD STAGE LATER THIS WEEK. THOUGH THE TRAP ROCK RIVER NEAR LAKE LINDEN HAS BEEN FALLING SINCE YESTERDAY EVENING...I AM NOT CONFIDENT THAT WE ARE IN THE CLEAR WITH THIS RIVER YET. WITH SNOW STILL ON THE GROUND...EXPECT THIS RIVER TO RISE THROUGH TOMORROW AS TEMPERATURES CLIMB WELL ABOVE NORMAL AND MELT ANY REMNANT SNOW COVER. WILL ALSO NEED TO KEEP AN EYE ON MIDDLE BRANCH OF ESCANABA NEAR HUMBOLDT FOR THE SAME REASONS AS THE TRAP ROCK. FOR THOSE GAUGES THAT DO END UP RISING ABOVE FLOOD STAGE THIS WEEK ONLY EXPECT MINOR FLOODING TO OCCUR. WILL HAVE TO MONITOR QPF AMOUNTS ON TUESDAY AFTERNOON/EVENING WITH EXPECTED THUNDERSTORM DEVELOPMENT. WITH THE FLASHY NATURE OF THE TRAP ROCK RIVER BASIN EVEN HALF AND INCH OF RAINFALL IN A SHORT TIME COULD CAUSE A RAPID RISE IN RIVER STAGE. FOR CONTINUED UPDATES ON THE RIVERS... PLEASE SEE THE LATEST HYDROLOGIC STATEMENTS AND ANY FLOOD WATCHES OR WARNINGS THAT MAY BE ISSUED. IN ADDITION...FOR THE LATEST FORECAST PLEASE VISIT THE AHPS PAGE AND CLICK ON A RIVER SITE...THIS CAN BE FOUND UNDER THE RIVERS AND LAKES LINK AT WWW.WEATHER.GOV/UP && .AVIATION (FOR THE 06Z TAF ISSUANCE)... UNCERTAINTY STILL EXISTS WITH THE FCST OVERNIGHT. KCMX AND KSAW ARE CURRENTLY VFR. QUESTION IS WHETHER FOG/STRATUS WILL DEVELOP OVER THE NEXT SEVERAL HRS. LOW-LEVEL WINDS APPEAR TO BE STRONG ENOUGH TO LIMIT FOG DEVELOPMENT...BUT WITH E TO SE UPSLOPE FLOW AT BOTH SITES AND UPSTREAM SFC DWPTS AROUND EXPECTED MIN TEMPS...FOG/STRATUS IS STILL A POSSIBILITY. NONETHELESS...GIVEN STRENGTH OF WINDS JUST OFF THE SFC AND THE FAIRLY DRY AIR PER EVENING RAOBS AND TAMDAR SOUNDINGS...WILL TREND A LITTLE MORE OPTIMISTIC FROM THE PREVIOUS FCST. WILL TAKE CONDITIONS AT KSAW DOWN TO MVFR LATER IN THE NIGHT WITH ONLY OCCASIONAL IFR AROUND SUNRISE AND KEEP KCMX VFR AS NO FOG ON THE LAKE CURRENTLY AND TEMP DEW POINT SPREAD IS GREAT ENOUGH NOT TO WORRY ABOUT AT THIS TIME. RAPID IMPROVEMENT AFTER SUNRISE TO VFR BY 14Z AT KSAW. VFR CONDITIONS WILL THEN CONTINUE THRU THE END OF THIS FCST PERIOD. && .MARINE (FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE)... WINDS WILL REMAIN BELOW 25 KNOTS UNTIL LATE THU INTO FRI WHEN WINDS WILL GET UP TO 30 KNOTS BEHIND A COLD FRONT WITH A TIGHTER PRESSURE GRADIENT BETWEEN A HIGH OVER THE PLAINS AND LOW PRESSURE EAST OF HERE. NO GALES SEEN ANYTIME SOON. && .MQT WATCHES/WARNINGS/ADVISORIES...NONE. && $$ DISCUSSION...DLG HYDROLOGY...DJP AVIATION...ROLFSON/GM MARINE...GM mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GAYLORD MI 110 AM EDT MON APR 21 2008 .AVIATION...A SCT TO BROKEN 10K-12K MID CLOUD DECK WILL HANG AROUND DURING THE PRE-DAWN HOURS...THE LAST INFLUENCE OF THE UPPER LEVEL DISTURBANCE IN THE MID ATLANTIC STATES. LOW LEVEL WINDS WILL TURN MORE SOUTHERLY LATER TODAY AS THAT SYSTEM DEPARTS...ALLOWING LOWER LEVEL MOISTURE TO RETURN NORTHWARD IN NW AND N CENTRAL LOWER MI MONDAY. THIS SHOULD RESULT IN A 5-6K FOOT CLOUD DECK AT TIMES FOR PLN/TVC MONDAY AFTERNOON AND EVENING. CONDITIONS STILL VFR THRU THE FORECAST. JZ && .UPDATE...ISSUED 929 PM SUN APR 20... AN UNEVENTFUL EVENING. WE FINALLY MANAGED TO SQUEEZE OUT SOME LATE AFTERNOON CU FROM GRAYLING/HTL WESTWARD...BUT NO SHOWERS. SKIES HAVE GONE MOSTLY CLEAR OVER NW/N CENTRAL LOWER MI...AND PARTS OF EASTERN UPPER. THERE IS ANOTHER BATCH OF MID AND HIGH CLOUDS ROTATING BACK ACROSS LAKE HURON...AND WILL ADJUST CLOUD GRIDS TO ACCOUNT FOR THIS. HOWEVER...THE UPPER LOW TO OUR SE IS ABOUT TO LOSE ITS INFLUENCE. UPPER RIDGING OVER THE NORTHERN/WESTERN LAKES WILL SLIDE SE...AS A REX BLOCK FORMS OVER THE EAST COAST. CIRRUS WILL STOP ITS INROADS AS THE UPPER RIDGE AXIS GRADUALLY SLIDES TO OUR SE...LATE TONIGHT AND ESPECIALLY DURING THE DAY ON MONDAY. LOW LEVELS AREN/T QUITE AS DRY AS THE LAST TWO DAYS...AND WE/LL SEE AN INCREASING CLOUD TREND FOR AT LEAST THE EARLY PART OF THE NIGHT. MIN TEMPS SHOULD BE NEAR OR SOMEWHAT WARMER THAN READINGS THE LAST FEW NIGHTS. ZOLTOWSKI && .PREV DISCUSSION...ISSUED 316 PM SUN APR 20... LATEST RUC ANALYSIS AND VIS/IR/WV/RADAR IMAGERY SHOW THE UPPER LEVEL FLOW CONTINUING TO BE DOMINATED BY THE CLOSED LOW OVER THE APPALACHIANS WHICH IS UNDERCUTTING A BROAD RIDGE OVER THE CENTRAL NOAM. MID-UPPER LEVEL CLOUDS WITHIN A DEFORMATION ZONE ACROSS THE UPPER PENINSULA HAVE BEEN SLOWING LIFTING NORTH LEAVING ALL OF NORTHERN MICHIGAN UNDER SUNNY OR MOSTLY SUNNY SKIES. AMPLE SUNSHINE COMBINED WITH THE LATE APRIL SUN HAVE HELPED TEMPERATURES RISE INTO THE MID TO UPPER 70S AWAY FROM THE GREAT LAKES WITH EVEN SOME REPORTS OF LOW 80S AROUND WELLSTON/PRUDENVILLE/BELLAIRE. RH LEVELS OVER THE HIGHER TERRAIN HAVENT DROPPED QUITE AS LOW AS EXPECTED YET...AND REMAIN BETWEEN 27-32F. MEANWHILE...ON THE NORTHEAST FLANK OF THE UPPER LOW...DEEP MOISTURE PLUME IS ROTATING NE TOWARDS LAKE ERIE BUT IS HAVING TROUBLE PENETRATING A VERY DRY AIRMASS ACROSS LOWER MICHIGAN. CLOUDS AND TEMPS REMAIN THE PRIMARY FORECAST CONCERNS THROUGH TOMORROW. TONIGHT...UNDERCUTTING UPPER LOW WILL SPIN TOWARDS THE MID-ATLANTIC COAST WHILE A SLIGHT INCREASE IN MID-LEVEL HEIGHTS OCCURS OVER THE GREAT LAKES. LOW-MID LEVEL MOISTURE PLUME ROTATING AROUND THE UPPER LOW WILL PIVOT NORTHWEST TOWARDS LAKE HURON AND NE LOWER/EASTERN UPPER TONIGHT. MODELS INDICATE TO VARIOUS DEGREES THAT THE MOISTURE PLUME FALLS APART AS IT REACHES NORTHERN MICHIGAN. THE GFS IS LESS AGGRESSIVE THAN THE NAM IN THIS REGARD...AND THINK THAT THE NAM IS THE BETTER WAY TO GO GIVEN THE VERY DRY AIRMASS IN PLACE. WILL INCREASE CLOUD COVER OVER EASTERN AND NORTHERN SECTIONS OF THE CWA TONIGHT...BUT WILL KEEP ONLY PARTLY CLOUDY SKIES IN THE FORECAST. LOWS GENERALLY IN THE 40S. TOMORROW...ANOTHER PLEASANT SPRING DAY IN STORE FOR NORTHERN MICHIGAN. A SMATTERING OF LOW-MID CLOUDS TO START THE MORNING WILL EVOLVE INTO A DIURNAL CU FIELD OVER INLAND AREAS FOR THE AFTERNOON. ANY CU THAT DOES DEVELOP LOOKS TO BE LIMITED BY A MID-LEVEL CAP BETWEEN 600-700MB. THIS CAP LOOKS POTENT ENOUGH TO KEEP A DRY FORECAST IN PLACE DESPITE A MORE MOIST PROFILE THAN TODAY AND LOCALIZED CONVERGENCE ALONG LAKE BREEZES ACROSS NW LOWER WITH THE PREVALENT NE FLOW. HOWEVER...IF HIGHER DEWPOINTS INTO THE UPPER 40S MATERIALIZE...THEN CHANCES FOR A SHOWER WILL INCREASE ALONG THE LAKE BREEZE. HIGHS SLIGHTLY COOLER IN THE UPPER 60S/LOW 70S AWAY FROM THE LAKES. MPC MON NIGHT THRU WED...PRIMARY FCST CONCERN REMAINS PRECIP CHANCES TUE AFTN/NIGHT ALONG WITH TEMPS. GUIDANCE REMAINS IN GOOD AGREEMENT WITH LARGE GYRE ACRS THE PACIFIC NORTHWEST OPENING UP THRU MON AFTN AS ADDITIONAL PACIFIC ENERGY BRIEFLY UNDERCUTS BLOCKING RIDGE INTO ALASKA...WITH REMNANT ENERGY SHEARING OUT THRU THE UPPER MIDWEST TUE AFTN/EVENING. ASSOCIATED SFC COLD FRONT STILL ON TRACK TO PUSH THRU THE REGION BETWEEN 00Z AND 12Z WED...WITH OBVIOUS INCREASING THREAT FOR PRECIP DURING THIS TIME. STILL APPEARS QG SUPPORT WILL SLIP NORTH OF THE REGION...THOUGH WITH DECENT MOISTURE TAP PER WIDE OPEN WESTERN GULF AND MODEST SFC-700MB CONVERGENCE ALONG INCOMING BOUNDARY...LIKELY POPS WARRANTED AT THIS TIME...IN LINE WITH PERSISTENT TREND OF OPERATIONAL AND ENSEMBLE GUIDANCE. BIGGEST QUESTION REMAINS WHAT WILL HAPPEN AHEAD OF THE FRONT...AS APPEARS DECENT HEATING LIKELY TO TAKE SHAPE IN THE THERMAL RIDGE (HIGHS UPR 60S TO MID 70S) TUE AFTN...WHILE SFC-850MB THETA-E RIDGE BUILDS INTO THE AREA. COUPLED WITH WEAKLY UPSLOPE REGIME PER BACKING OF LOW LEVEL FLOW AHEAD OF INCOMING FRONT...AS WELL AS MODEL HINTS OF ENHANCED CONVERGENCE ALONG DEVELOPING PRE-FRONTAL TROUGH...DIFFICULT TO RULE OUT SCATTERED CONVECTION FIRING ACRS THE WESTERN CWA. FCST RAOBS WITH A 72/48 PARCEL (WHICH SHOULD BE ACHIEVABLE) YIELD 200-300 J/KG MLCAPE...THOUGH ARGUABLY GUIDANCE MAY BE OVERDOING MOISTURE JUST A TAD. IN EITHER CASE...CHANCY POPS CERTAINLY WARRANTED... ESPECIALLY WITH LATEST TREND FOR GUIDANCE TO SPEED UP TIMING OF ENTIRE SYSTEM. SHOULD SEE A QUICK END TO PRECIP BY SUNRISE WED AS LOW/MID LEVEL RIDGING QUICKLY TAKE HOLD...WITH RAPID CLEARING IN THE WAKE OF FROPA WITH 1000-500MB RH FALLING OFF THE TABLE TO AROUND 25% VIA STRONG SUBSIDENCE. COOLER READINGS IN THE MID 50S TO MID 60S WARRANTED FOR WED AFTN WITH QUICK SHOT OF COLD ADVECTION (H85 TEMPS DIP TO AROUND 3-5C PER GEFS MEAN - OPERATIONAL GFS WAY TOO COOL)...THOUGH LIKELY OFFSET BY INSOLATION OUTSIDE OF PERHAPS AFTN CU GIVEN THERMAL TROUGH OVERHEAD. LATER PERIODS (WED NIGHT THRU SUN)...RATHER BLOCKY PATTERN TO PERSIST THRU THE PERIOD...WITH HIGHLY AMPLIFIED/CLOSED MID LEVEL RIDGING ACRS ALASKA FAVORING DOWNSTREAM TROUGHING OVR CENTRAL CANADA...WITH AN EXTENSION INTO THE NORTHERN CONUS. MEDIUM RANGE GUIDANCE REMAINS IN GOOD AGREEMENT WITH THIS OVERALL SETUP...THOUGH SOME DIFFERENCES REMAIN WITH DEGREE OF AMPLIFICATION OF THE WESTERN CONUS TROUGH. STILL APPEARS A NICE DAY ON TAP FOR THU AS LOW/MID LEVEL RIDGE AND ASSOCIATED SUBSIDENCE/DRYING BUILDS OVERHEAD IN THE WAKE OF FRONTAL PASSAGE. SHOULD END UP BEING A RATHER SUNNY DAY...OUTSIDE OF SOME POTENTIAL INCREASE IN JET-DRIVEN CIRRUS BY AFTN...WITH GUIDANCE NUMBERS STILL APPEARING TO BE JUST A TOUCH TOO COOL GIVEN EXPECTED INSOLATION. THEREAFTER...INCREASING PRECIP CHANCES IN ORDER FRI/SAT TIMEFRAME AS ENERGY UNDERCUTTING PACIFIC BLOCKING RIDGE AIDS IN KICKING WESTERN TROUGH EASTWARD...WITH ASSOCIATED LEE CYCLONE DEVELOPMENT/SFC FRONTOGENESIS TAKING PLACE ACRS THE PLAINS BEFORE MAKING A RUN TOWARD THE NORTHERN LAKES. POTENTIAL FOR ANOTHER QUITE WARM DAY ON FRI WITH REGION FALLING IN THE THERMAL RIDGE AHEAD OF APPROACHING FRONT...AND HAVE THUS GONE ABOVE GUIDANCE ONCE AGAIN. ALSO SOME POTENTIAL FOR THUNDER WITH INCOMING FRONT...THOUGH WILL HOLD OFF ON MENTION AT THIS TIME WITH SOME REMAINING TIMING ISSUES. LAWRENCE && .APX WATCHES/WARNINGS/ADVISORIES... MI...NONE. LM...NONE. LH...NONE. LS...NONE. && $$ mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WILMINGTON OH 523 AM EDT MON APR 21 2008 .SYNOPSIS... AN UPPER LEVEL RIDGE OF HIGH PRESSURE WILL BUILD ACROSS THE REGION THROUGH TUESDAY. DRY WEATHER ALONG WITH ABOVE NORMAL TEMPERATURES CAN BE EXPECTED. && .NEAR TERM /UNTIL NOON TODAY/... MAIN FORECAST CONCERN FOR TODAY WILL BE THE FOG ACRS THE WRN HALF OF THE FCST AREA. THE COMBINATION OF YESTERDAY/S RAINFALL...CLEAR SKIES AND LIGHT WINDS HAVE RESULTED IN LOW STRATUS AND FOG. AREAS OF DENSE FOG CAN BE EXPECTED UNTIL 10 AM EDT...AND HAVE THUS ISSUED A DENSE FOG ADVISORY ACCORDINGLY. LOW CLOUDS AND FOG WILL BURN OFF BY AFTERNOON...LEAVING PARTLY SUNNY SKIES. && .SHORT TERM /NOON TODAY THROUGH WEDNESDAY NIGHT/... MID LVL RIDGING WILL DEVELOP ACRS THE REGION THIS AFTN IN THE WAKE OF DEPARTING UPPER LEVEL CLOSED LOW. BELIEVE OPERATIONAL GFS AND NAM-WRF ARE OVERDONE WITH THEIR FCST INSTABILITY FOR THIS AFTN...AND THUS...WILL NOT BUY INTO THEIR LIGHT QPF FOR THE ERN FCST AREA BY LATE THIS AFTN. THUS...AM EXPECTING JUST PARTLY SUNNY SKIES AND WARM TEMPERATURES. HIGHS WILL BE MAINLY IN THE LOWER 70S. FOR TONIGHT AND TUESDAY...MID LVL RIDGING WILL REMAIN IN PLACE ACROSS THE ERN GREAT LAKES AND OHIO VALLEY REGION. SKIES WILL BE MOSTLY CLEAR AT NIGHT AND MOSTLY SUNNY DURING THE DAY. TEMPERATURES WILL WARM INTO THE MID 70S. FOR TUESDAY NIGHT INTO WEDNESDAY....A WEAKENING COLD FRONT WILL APCH THE REGION FROM THE NORTHWEST. OPERATIONAL NAM-WRF BRINGS FRONT INTO NRN INDIANA AND NRN OHIO ON WEDNESDAY...WHILE THE OPERATIONAL GFS TRIES TO PUSH THE FRONT SOUTH TOWARD THE OHIO RIVER BY WEDNESDAY EVENING. LATEST SREF AND GFS ENSEMBLE MEANS SUPPORT THE IDEA OF ONLY PUSHING THE FRONT INTO FAR NRN INDIANA AND FAR NRN OHIO AS MID LVL RIDGING ACTUALLY BUILDS MORE ON WEDNESDAY. THUS...AM HAVING MY DOUBTS ABOUT PCPN FOR WEDNESDAY DUE TO THE MID LVL RIDGING BECOMING STRONGER...THUS KEEPING THE FRONT AT BAY...AND EVENTUALLY WASHING IT OUT. AS A COMPROMISE BETWEEN HPC AND SURROUNDING OFFICES...HAVE KEPT A SLIGHT CHANCE FOR SHOWERS AND THUNDERSTORMS ROUGHLY ALONG AND NORTH OF I-70 FOR WEDNESDAY. LATER FORECASTS WILL HAVE TO DETERMINE IF IT MAY EVENTUALLY BE DRY. TEMPERATURES WILL CONTINUE ABOVE NORMAL WITH HIGHS IN THE MID AND UPPER 70S. FOR WEDNESDAY NIGHT...AFOREMENTIONED FRONTAL BOUNDARY WILL HAVE WASHED OUT. MID LVL RIDGING WILL REMAIN IN PLACE. && .LONG TERM /THURSDAY THROUGH SUNDAY/... MID LVL RIDGE REESTABLISHES THURS WITH DRY WEATHER FOR THE OH VLY. WITH 850 TEMPS CLIMBING TO 13-14C AND AMPLE SUNSHINE EXPECTED THURS AFTN...HAVE NUDGED TEMPS UP INTO THE M/U70S. SVRL LOCATIONS COULD APPCH 80 DEG. WARM FRONT WILL LIFT NORTH ACRS THE REGION LATE THURS NIGHT INTO FRI AS SFC LO MOVES INTO THE WESTERN GRT LKS. PCPN CHANCES WILL BEGINNING TO INCREASE LATE THURS NIGHT BUT EXPECT PCPN TO REMAIN RELATIVELY SCATTERED WITH PRESENCE OF SFC HI RIDGE JUST EAST OF REGION. FCST AREA IN WARM SECTOR FRI AS COLD FRONT APPCHS FROM THE MID MISSISSIPPI VLY. PLENTY OF MOISTURE AND INSTABILITY IN PLACE AHEAD OF THE FRONT FOR SCT TSTMS FRI/FRI NIGHT. TRENDED TOWARDS 00Z GFS/UKMET WHICH HAVE A MORE PROGRESSIVE MOVEMENT TO FRONT...WITH FROPA FRI NIGHT ACRS FCST AREA. HAVE INCREASED TO NEAR 50 POPS FOR FRI AFTN/NIGHT. SFC HI PRES WILL BUILD IN FROM THE NORTHWEST SAT WITH PCPN ENDING AS DRIER AIR ADVECTS INTO THE REGION. NW FLO ALOFT WILL ENSURE COOLER AND MORE SEASONABLE TEMPS OVER THE WEEKEND...WITH AFTN HIGHS IN THE 60S AND LOWS IN THE 40S. && .AVIATION /10Z MONDAY THROUGH FRIDAY/... WEAK SFC HI HAS BUILT INTO THE REGION ERLY THIS MRNG. WEAK FLO THRU THE BNDRY LYR COMBINED WITH A STRONG SHALLOW INVERSION HAS CONTRIBUTED TO IFR ST DECK ACRS WESTERN FCST AREA. ST HAS EXPANDED INTO KCVG/KLUK/KDAY TERMINALS WITH VSBYS CRASHING BELOW 1SM. CURRENT RUC ANALYSIS INDCG ST NOT LKLY TO MOVE MUCH AT ALL OVER NEXT SVRL HOURS AS LO LVL STEERING CURRENTS REMAIN WEAK. EXPECT LIFR/VLIFR CONDITIONS TO PERSIST IN THE CVG/DAY METRO AREAS FOR NEXT FEW HOURS. AS ERLY LO LVL FLO BECOMES ESTABLISHED TOWARDS DAYBREAK...MAY SEE SOME SUBTLE IMPROVEMENTS AT KDAY. SHALLOW MVFR GROUND FOG WILL BE POSSIBLE AT REMAINING TERMINALS THRU DAWN. INVERSION WILL SLOWLY BREAK DOWN DURING THE MRNG WITH BNDRY LYR MIXING REFOCUSING CU DVLPMNT NEAR 4KFT BY ERLY AFTN. HAVE A FEELING MVFR HZ WILL LINGER AT KCVG/KLUK/KDAY FOR GOOD PART OF THE MORNING BEFORE MORE EFFICIENT LO LVL MIXING CAN ESTABLISH. BKN CU FIELD WILL PERSIST ACRS FCST AREA THRU THE AFTN. CU WILL THEN DIMINISH THIS EVNG WITH LOSS OF DAYTIME HEATING. OUTLOOK...NO SIGNIFICANT WEATHER IS EXPECTED. && .ILN WATCHES/WARNINGS/ADVISORIES... OH...DENSE FOG ADVISORY UNTIL 10 AM EDT THIS MORNING FOR OHZ026-034- 035-042>044-051>053-060>062-070>072-077>079. KY...DENSE FOG ADVISORY UNTIL 10 AM EDT THIS MORNING FOR KYZ089>098. IN...DENSE FOG ADVISORY UNTIL 10 AM EDT THIS MORNING FOR INZ050-058- 059-066-073>075-080. && $$ SYNOPSIS...HICKMAN NEAR TERM...HICKMAN SHORT TERM...HICKMAN LONG TERM...RYAN AVIATION...RYAN oh AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WILMINGTON OH 115 AM EDT MON APR 21 2008 .SYNOPSIS... A CLOSED UPPER LOW OVER THE CENTRAL APPALACHIANS WILL SLIDE OFF TO THE EAST TONIGHT...AS UPPER LEVEL RIDGING BUILDS INTO THE OHIO VALLEY. THIS RIDGE WILL REMAIN IN PLACE ACROSS THE REGION UNTIL LATE TUESDAY...WHEN AN UPPER SHORTWAVE SWINGS THROUGH THE GREAT LAKES. && .NEAR TERM /UNTIL 6 AM THIS MORNING/... ELONGATED UPPER LOW OVER VIRGINIA TO CONTINUE TO TRACK ESE AWAY FROM THE REGION. PRECIPITATION HAS COME TO END WITH THE LOSS OF DAYTIME HEATING. WITH PRECIP ENDING HAVE DROPPED ANY MENTION OF RAIN TONIGHT. A GOOD DEAL OF CLEARING HAS OCCURRED THIS EVENING...BUT LATEST IR SATL IMGRY SHOWING STRATUS DEVELOPING WHERE RAIN HAS FALLEN OVER SW OHIO/SE INDIANA AND NRN KY. EXPECT THIS STATUS TO CONT TO EXPAND WITH PATCHY FOG DEVELOPING OVERNIGHT. HAVE REFLECTED THIS IN EVENING ZONE UPDATE. && .SHORT TERM /6 AM THIS MORNING THROUGH TUESDAY NIGHT/... UPPER LOW CONTINUES TO PUSH EAST ON MONDAY AS UPPER RIDGING BUILDS INTO THE OHIO VALLEY. DESPITE SOME WEAK INSTBY...MODELS SEEM TO BE OVERDOING THE PRECIP ON THE BACK EDGE OF THE UPPER LOW...ESPECIALLY GIVEN THE AMOUNT OF SUBSIDENCE EXPECTED WITHIN THE RIDGE. THEREFORE WENT AGAINST THE MODELS AND KEPT THE FORECAST DRY FOR MONDAY. WILL SEE SOME SCATTERED CU REDEVELOP...ESPECIALLY ACROSS THE EAST. FLOW BEHIND THE DEPARTING UPPER LOW WILL BE QUICK TO TURN TO THE SOUTH WHICH BRINGS ABOVE AVG TEMPS BACK TO THE REGION BY MONDAY AFTERNOON. TEMPS WILL CONTINUE TO WARM ON TUESDAY AS SFC FLOW BACKS TO SOUTHWESTERLY AHEAD OF UPPER LOW OVER THE SOUTHERN PLAINS. THIS SYSTEM WILL QUICKLY EJECT INTO THE GREAT LAKES TUESDAY NIGHT...SENDING A WEAK FRONT TO JUST WEST OF THE CWA BY SUNRISE WEDNESDAY. EXPECT TO SEE CONVECTIVE DEVELOPMENT ALONG THE FRONT OVER THE MISSISSIPPI VALLEY TUESDAY AFTERNOON...THEN WEAKEN AS IT ENCOUNTERS AN INCREASINGLY STABLE AIRMASS OVER THIS REGION. STUCK CLOSER TO SLOWER NAM TIMING WITH THIS PRECIP...BRINGING ONLY A SLIGHT CHANCE TO THE WESTERN ZONES LATE TUES NIGHT. IF A MORE ORGANIZED CONVECTIVE LINE DEVELOPS TO THE WEST TUESDAY EVE...POPS WILL LIKELY NEED TO BE SPED UP INTO THIS AREA. && .LONG TERM /WEDNESDAY THROUGH SUNDAY/... MID LEVEL RIDGING ACROSS THE EASTERN UNITED STATES WILL FLATTEN OUT A BIT AS MID LEVEL SHORT WAVE PUSHES ACROSS THE GREAT LAKES ON WEDNESDAY. THIS WILL ALLOW FOR A WEAKENING COLD FRONT TO PUSH DOWN INTO OUR AREA THROUGH THE DAY. WITH BOTH MOISTURE AND FORCING SOMEWHAT LIMITED...WILL STILL ONLY CARRY A 30-40 POP FOR THIS SYSTEM WEDNESDAY INTO WEDNESDAY EVENING. RIDGING WILL THEN BRIEFLY RE-ESTABLISH ITSELF ACROSS THE REGION THURSDAY BEFORE BEGINNING TO BREAK DOWN ON FRIDAY AS TROUGH OVER CENTRAL UNITED STATES WORKS ITS WAY EAST. AS THIS HAPPENS...A DEVELOPING SURFACE LOW WILL LIFT NORTHEAST OUT OF THE SOUTHERN PLAINS AND INTO THE UPPER GREAT LAKES THROUGH SATURDAY. AHEAD OF THE LOW...A WARM FRONT WILL LIFT UP ACROSS OUR AREA ON FRIDAY BEFORE A COLD FRONT SWEEPS THROUGH THE REGION LATE FRIDAY NIGHT INTO SATURDAY. THIS WILL LEAD TO A CHANCE OF SHOWERS AND THUNDERSTORMS FRIDAY AND FRIDAY NIGHT...TAPERING OFF TO A FEW WRAP AROUND SHOWERS DURING THE DAY ON SATURDAY. HAVE GENERALLY GONE AT OR A LITTLE ABOVE GUIDANCE WITH BOTH HIGHS AND LOWS AHEAD OF THE FRONT THROUGH FRIDAY. && .AVIATION /06Z MONDAY THROUGH FRIDAY/... WEAK SFC HI HAS BUILT INTO THE REGION ERLY THIS MRNG. WEAK FLO THRU THE BNDRY LYR COMBINED WITH A STRONG SHALLOW INVERSION HAS CONTRIBUTED TO IFR ST DECK ACRS WESTERN FCST AREA. ST HAS EXPANDED INTO KCVG/KLUK/KDAY TERMINALS WITH VSBYS CRASHING BELOW 1SM. CURRENT RUC ANALYSIS INDCG ST NOT LKLY TO MOVE MUCH AT ALL OVER NEXT SVRL HOURS AS LO LVL STEERING CURRENTS REMAIN WEAK. EXPECT LIFR/VLIFR CONDITIONS TO PERSIST IN THE CVG/DAY METRO AREAS FOR NEXT FEW HOURS. AS ERLY LO LVL FLO BECOMES ESTABLISHED TOWARDS DAYBREAK...MAY SEE SOME SUBTLE IMPROVEMENTS AT KDAY. SHALLOW MVFR GROUND FOG WILL BE POSSIBLE AT REMAINING TERMINALS THRU DAWN. INVERSION WILL SLOWLY BREAK DOWN DURING THE MRNG WITH BNDRY LYR MIXING REFOCUSING CU DVLPMNT NEAR 4KFT BY ERLY AFTN. HAVE A FEELING MVFR HZ WILL LINGER AT KCVG/KLUK/KDAY FOR GOOD PART OF THE MORNING BEFORE MORE EFFICIENT LO LVL MIXING CAN ESTABLISH. BKN CU FIELD WILL PERSIST ACRS FCST AREA THRU THE AFTN. CU WILL THEN DIMINISH THIS EVNG WITH LOSS OF DAYTIME HEATING. OUTLOOK...NO SIGNIFICANT WEATHER IS EXPECTED. && .ILN WATCHES/WARNINGS/ADVISORIES... OH...NONE. KY...NONE. IN...NONE. && $$ SYNOPSIS...AR NEAR TERM...HAWBLITZEL SHORT TERM...HAWBLITZEL LONG TERM...JGL AVIATION...RYAN oh AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LOUISVILLE KY 1112 AM EDT MON APR 21 2008 .MORNING UPDATE #3... UPDATED ZONES TO REMOVE FOG ADVY SINCE DENSE FOG HAS LIFTED. A LINGERING DECK OF STRATUS SHOULD STICK AROUND IN THE FAR NE FORECAST AREA (FA) FOR THE NEXT COUPLE OF HOURS BEFORE DISSIPATING. ONLY MINOR ADJUSTMENTS TO TEMPS UPPING HIGHS A DEGREE OR TWO IN THE SW FA AS CLEAR SKIES THIS MORNING HAVE BROUGHT THEM INTO THE LOWER 60S ALREADY. EXPECT A NE TO SW TEMP GRADIENT TODAY WITH THE COOLER TEMPS IN AREAS THAT RECEIVED THE DENSE FOG THIS MORNING. NEVERTHELESS IT SHOULD BE A BEAUTIFUL MONDAY WITH HIGHS IN THE 70S AND PLENTY OF SUNSHINE. .MORNING UPDATE #2... UPDATED THE ZONES TO INCLUDE THE DENSE FOG ADVY TILL 10 AM EDT. .EARLY MORNING UPDATE... HAVE EXPENDED DENSE FOG ADVISORY TO INCLUDE ADDITIONAL COUNTIES ACROSS SOUTHERN INDIANA AND THE SOUTHERN BLUEGRASS REGION. DENSE FOG MAY WELL PERSIST AN HOUR OR SO AFTER SUNRISE PRIOR TO DISSIPATING. .SHORT TERM (TODAY AND TONIGHT)... ONLY WEATHER CONCERNS IN THE SHORT TERM WILL BE FOG THIS MORNING. LOW CLOUDS WILL CONTINUE TO ERODE DURING THE PRE-DAWN HOURS. BOUNDARY LEVEL WINDS ARE QUITE LIGHT AND FROM THE SOUTHEAST. SKIES HAVE ALREADY CLEARED ACROSS THE BLUEGRASS. THE RUC SEEMS TO HAVE LATCHED ON TO THE DEVELOPING FOG AND LOWERS VISIBILITIES QUITE A BIT ACROSS SOUTHERN INDIANA AND CENTRAL KENTUCKY...ESPECIALLY THE BLUEGRASS REGION. WILL MAINTAIN MENTION OF PATCHY DENSE FOG. MAY ISSUE A DENSE FOG ADVISORY SHOULD VISIBILITIES LOWER TO 1/2 MILE OVER A BROAD AREA. UPPER AIR PATTERN IS CURRENTLY QUITE BLOCKY. A CUTOFF UPPER LOW NOW ACROSS THE MID-ATLANTIC WILL SAG SOUTHEASTWARD VERY SLOWLY OVER THE NEXT COUPLE OF DAYS. ACROSS THE PACIFIC NORTHWEST A UNSEASONABLY DEEP AND COLD UPPER LOW WILL REMAIN IN PLACE. AS IS TYPICAL OF CUTOFF LOWS...AREAS AROUND THE DISTURBANCE NOT AFFECTED BY CLOUDINESS WILL EXPERIENCE QUITE MILD WEATHER. THIS WILL BE TRUE FOR THE GREAT LAKES AND NEW ENGLAND TODAY AND TOMORROW. THE CUTOFF LOW TO OUR EAST WILL LOSE ITS INFLUENCE ACROSS THE LOWER OHIO VALLEY TODAY. TEMPERATURES SHOULD WARM NICELY THIS AFTERNOON UNDER MOSTLY SUNNY SKIES. WITH A VIRTUALLY NON-EXISTENT PRESSURE GRADIENT...WINDS WILL BE QUITE LIGHT AND VARIABLE. MOSTLY CLEAR SKIES WILL CONTINUE TONIGHT. PATCHY FOG IS QUITE POSSIBLE AGAIN TOMORROW MORNING. .LONG TERM (MONDAY NIGHT THROUGH SUNDAY)... TUESDAY THROUGH WEDNESDAY NIGHT... A SLOW MOVING COLD FRONT AND WEAK UPPER TROUGH WILL STRUGGLE TO MAKE INROADS INTO AN UPPER LEVEL RIDGE THAT WILL BE BUILDING OVER THE SOUTHEAST UNITED STATES AND THE CWA TUESDAY AND WEDNESDAY. CURRENT MODEL SOLUTIONS CONTINUE PREVIOUS TREND OF SLOWING FRONT DOWN AND PUSHING MAIN ENERGY INTO THE NORTHERN GREAT LAKES TUESDAY NIGHT AND WEDNESDAY...INSTEAD OF BRINGING IT INTO SOUTH CENTRAL INDIANA AND CENTRAL KENTUCKY. PER COORDINATION WITH NEIGHBORING OFFICES HAVE DRIED OUT THE FORECAST FOR TUESDAY NIGHT THROUGH WEDNESDAY NIGHT TO ACCOUNT FOR THIS. LATEST GFS AND NAM MODELS BOTH INDICATING UPPER RIDGE AXIS MAY BE DIRECTLY OVER TOP OF THE CWA LATE WEDNESDAY INTO THURSDAY...WHICH COULD MEAN DRY WEATHER FOR THURSDAY AND BEYOND ALSO. FOR NOW WILL NOT MAKE ANY CHANGES TO THE THURSDAY AND AFTER PERIOD AND MONITOR MODELS AND TRENDS AT A LATER TIME. PREVIOUS FORECAST DISCUSSION FOR THURSDAY THROUGH SUNDAY BELOW. THU THRU SUN... THIS FORECAST LEANS TOWARD THE GFS ENSEMBLES AND HPC WITH ASSISTS FROM THE ECMWF AND CANADIAN ENSEMBLES. CONSENSUS FROM THE ENSEMBLES AND HPC IS THAT A WARM FRONT WILL MOVE THRU OUR FA THU WITH A CDFNT APPROACHING AND MOVING THRU FRI NIGHT. UPR LEVEL TROF IN ARREARS OF FRONT TO APPROACH/MOVE THRU SAT. AT THIS POINT...THE GUIDANCE POINTS AT LATE FRI/FRI NIGHT AS THE BEST CHC FOR WIDESPREAD CONVECTIVE RAINFALL ASSOCIATED WITH FRONTAL APPROACH/PASSAGE. IT IS THIS PERIOD...WHERE WE WILL INSERT HIGHEST CHC POPS. FOR THU AFTN THRU FRI AFTN...WILL LEAVE 20 TO 40% POPS AS WMFNT REACHES UPR OH VLY BY EARLY FRI WITH CDFNT ACRS MO AT THAT TIME...AND MOISTURE TRANSPORT INCREASING ON SLY FLO. DEBATED ABOUT LEAVING SAT DRY PER OUR CURRENT FCST FAVORING THE ECMWF...BUT GENERALLY WENT WITH HPC/GFS ENSEMBLES WITH SMALL CHC POPS FOR POST FRONTAL SHOWERS AHEAD OF AFOREMENTIONED UPR LEVEL TROF. WILL END RAIN CHCS SAT NIGHT AND CONTINUE INTO SUN AS HIGH PRESSURE TRACKS FROM THE MID MS VLY INTO THE WESTERN OH VLY. TEMPS WILL BE WARMEST...ABOVE LATE APR SEASONAL NORMS...ON THU AND FRI WITH WMFROPA AND PRECDFNT. COOLEST TEMPS TO OCCUR SAT AND SUN NIGHT (GENERALLY 40 TO 45) OWING TO COLD ADVECTION SAT NIGHT AND RADIATIONAL COOLING SUN NIGHT AS 850 TEMPS DROP TO 1-5C. && .AVIATION (12Z TAFS)... DENSE FOG WILL CONTINUE AT LEX THROUGH 12 TO 13Z. FOG AT SDF AND BWG WILL BE LIGHTER...WITH VISIBILITES DROPPING ONLY TO 2 TO 3SM. AFTER FOG ERODES AFTER 13Z...EXPECT MOSTLY CLEAR SKIES AND LIGHT WINDS THIS AFTERNOON. FOG MAY REFORM EARLY TOMORROW...BUT WILL NOT BE NEARLY AS DENSE AS THIS MORNING`S. && .LMK WATCHES/WARNINGS/ADVISORIES... KY...NONE. IN...NONE. && $$ UPDATES......JSD/AML SHORT TERM...JSD LONG TERM....MACZKO/13 AVIATION.....JSD/AML ky AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LOUISVILLE KY 806 AM EDT MON APR 21 2008 .MORNING UPDATE #2... UPDATED THE ZONES TO INCLUDE THE DENSE FOG ADVY TILL 10 AM EDT. .EARLY MORNING UPDATE... HAVE EXPENDED DENSE FOG ADVISORY TO INCLUDE ADDITIONAL COUNTIES ACROSS SOUTHERN INDIANA AND THE SOUTHERN BLUEGRASS REGION. DENSE FOG MAY WELL PERSIST AN HOUR OR SO AFTER SUNRISE PRIOR TO DISSIPATING. .SHORT TERM (TODAY AND TONIGHT)... ONLY WEATHER CONCERNS IN THE SHORT TERM WILL BE FOG THIS MORNING. LOW CLOUDS WILL CONTINUE TO ERODE DURING THE PRE-DAWN HOURS. BOUNDARY LEVEL WINDS ARE QUITE LIGHT AND FROM THE SOUTHEAST. SKIES HAVE ALREADY CLEARED ACROSS THE BLUEGRASS. THE RUC SEEMS TO HAVE LATCHED ON TO THE DEVELOPING FOG AND LOWERS VISIBILITIES QUITE A BIT ACROSS SOUTHERN INDIANA AND CENTRAL KENTUCKY...ESPECIALLY THE BLUEGRASS REGION. WILL MAINTAIN MENTION OF PATCHY DENSE FOG. MAY ISSUE A DENSE FOG ADVISORY SHOULD VISIBILITIES LOWER TO 1/2 MILE OVER A BROAD AREA. UPPER AIR PATTERN IS CURRENTLY QUITE BLOCKY. A CUTOFF UPPER LOW NOW ACROSS THE MID-ATLANTIC WILL SAG SOUTHEASTWARD VERY SLOWLY OVER THE NEXT COUPLE OF DAYS. ACROSS THE PACIFIC NORTHWEST A UNSEASONABLY DEEP AND COLD UPPER LOW WILL REMAIN IN PLACE. AS IS TYPICAL OF CUTOFF LOWS...AREAS AROUND THE DISTURBANCE NOT AFFECTED BY CLOUDINESS WILL EXPERIENCE QUITE MILD WEATHER. THIS WILL BE TRUE FOR THE GREAT LAKES AND NEW ENGLAND TODAY AND TOMORROW. THE CUTOFF LOW TO OUR EAST WILL LOSE ITS INFLUENCE ACROSS THE LOWER OHIO VALLEY TODAY. TEMPERATURES SHOULD WARM NICELY THIS AFTERNOON UNDER MOSTLY SUNNY SKIES. WITH A VIRTUALLY NON-EXISTENT PRESSURE GRADIENT...WINDS WILL BE QUITE LIGHT AND VARIABLE. MOSTLY CLEAR SKIES WILL CONTINUE TONIGHT. PATCHY FOG IS QUITE POSSIBLE AGAIN TOMORROW MORNING. .LONG TERM (MONDAY NIGHT THROUGH SUNDAY)... TUESDAY THROUGH WEDNESDAY NIGHT... A SLOW MOVING COLD FRONT AND WEAK UPPER TROUGH WILL STRUGGLE TO MAKE INROADS INTO AN UPPER LEVEL RIDGE THAT WILL BE BUILDING OVER THE SOUTHEAST UNITED STATES AND THE CWA TUESDAY AND WEDNESDAY. CURRENT MODEL SOLUTIONS CONTINUE PREVIOUS TREND OF SLOWING FRONT DOWN AND PUSHING MAIN ENERGY INTO THE NORTHERN GREAT LAKES TUESDAY NIGHT AND WEDNESDAY...INSTEAD OF BRINGING IT INTO SOUTH CENTRAL INDIANA AND CENTRAL KENTUCKY. PER COORDINATION WITH NEIGHBORING OFFICES HAVE DRIED OUT THE FORECAST FOR TUESDAY NIGHT THROUGH WEDNESDAY NIGHT TO ACCOUNT FOR THIS. LATEST GFS AND NAM MODELS BOTH INDICATING UPPER RIDGE AXIS MAY BE DIRECTLY OVER TOP OF THE CWA LATE WEDNESDAY INTO THURSDAY...WHICH COULD MEAN DRY WEATHER FOR THURSDAY AND BEYOND ALSO. FOR NOW WILL NOT MAKE ANY CHANGES TO THE THURSDAY AND AFTER PERIOD AND MONITOR MODELS AND TRENDS AT A LATER TIME. PREVIOUS FORECAST DISCUSSION FOR THURSDAY THROUGH SUNDAY BELOW. THU THRU SUN... THIS FORECAST LEANS TOWARD THE GFS ENSEMBLES AND HPC WITH ASSISTS FROM THE ECMWF AND CANADIAN ENSEMBLES. CONSENSUS FROM THE ENSEMBLES AND HPC IS THAT A WARM FRONT WILL MOVE THRU OUR FA THU WITH A CDFNT APPROACHING AND MOVING THRU FRI NIGHT. UPR LEVEL TROF IN ARREARS OF FRONT TO APPROACH/MOVE THRU SAT. AT THIS POINT...THE GUIDANCE POINTS AT LATE FRI/FRI NIGHT AS THE BEST CHC FOR WIDESPREAD CONVECTIVE RAINFALL ASSOCIATED WITH FRONTAL APPROACH/PASSAGE. IT IS THIS PERIOD...WHERE WE WILL INSERT HIGHEST CHC POPS. FOR THU AFTN THRU FRI AFTN...WILL LEAVE 20 TO 40% POPS AS WMFNT REACHES UPR OH VLY BY EARLY FRI WITH CDFNT ACRS MO AT THAT TIME...AND MOISTURE TRANSPORT INCREASING ON SLY FLO. DEBATED ABOUT LEAVING SAT DRY PER OUR CURRENT FCST FAVORING THE ECMWF...BUT GENERALLY WENT WITH HPC/GFS ENSEMBLES WITH SMALL CHC POPS FOR POST FRONTAL SHOWERS AHEAD OF AFOREMENTIONED UPR LEVEL TROF. WILL END RAIN CHCS SAT NIGHT AND CONTINUE INTO SUN AS HIGH PRESSURE TRACKS FROM THE MID MS VLY INTO THE WESTERN OH VLY. TEMPS WILL BE WARMEST...ABOVE LATE APR SEASONAL NORMS...ON THU AND FRI WITH WMFROPA AND PRECDFNT. COOLEST TEMPS TO OCCUR SAT AND SUN NIGHT (GENERALLY 40 TO 45) OWING TO COLD ADVECTION SAT NIGHT AND RADIATIONAL COOLING SUN NIGHT AS 850 TEMPS DROP TO 1-5C. && .AVIATION (12Z TAFS)... DENSE FOG WILL CONTINUE AT LEX THROUGH 12 TO 13Z. FOG AT SDF AND BWG WILL BE LIGHTER...WITH VISIBILITES DROPPING ONLY TO 2 TO 3SM. AFTER FOG ERODES AFTER 13Z...EXPECT MOSTLY CLEAR SKIES AND LIGHT WINDS THIS AFTERNOON. FOG MAY REFORM EARLY TOMORROW...BUT WILL NOT BE NEARLY AS DENSE AS THIS MORNING`S. && .LMK WATCHES/WARNINGS/ADVISORIES... KY...NONE. IN...NONE. && $$ SHORT TERM...JSD LONG TERM....MACZKO/13 AVIATION.....JSD ky AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LOUISVILLE KY 630 AM EDT MON APR 21 2008 .EARLY MORNING UPDATE... HAVE EXPENDED DENSE FOG ADVISORY TO INCLUDE ADDITIONAL COUNTIES ACROSS SOUTHERN INDIANA AND THE SOUTHERN BLUEGRASS REGION. DENSE FOG MAY WELL PERSIST AN HOUR OR SO AFTER SUNRISE PRIOR TO DISSIPATING. .SHORT TERM (TODAY AND TONIGHT)... ONLY WEATHER CONCERNS IN THE SHORT TERM WILL BE FOG THIS MORNING. LOW CLOUDS WILL CONTINUE TO ERODE DURING THE PRE-DAWN HOURS. BOUNDARY LEVEL WINDS ARE QUITE LIGHT AND FROM THE SOUTHEAST. SKIES HAVE ALREADY CLEARED ACROSS THE BLUEGRASS. THE RUC SEEMS TO HAVE LATCHED ON TO THE DEVELOPING FOG AND LOWERS VISIBILITIES QUITE A BIT ACROSS SOUTHERN INDIANA AND CENTRAL KENTUCKY...ESPECIALLY THE BLUEGRASS REGION. WILL MAINTAIN MENTION OF PATCHY DENSE FOG. MAY ISSUE A DENSE FOG ADVISORY SHOULD VISIBILITIES LOWER TO 1/2 MILE OVER A BROAD AREA. UPPER AIR PATTERN IS CURRENTLY QUITE BLOCKY. A CUTOFF UPPER LOW NOW ACROSS THE MID-ATLANTIC WILL SAG SOUTHEASTWARD VERY SLOWLY OVER THE NEXT COUPLE OF DAYS. ACROSS THE PACIFIC NORTHWEST A UNSEASONABLY DEEP AND COLD UPPER LOW WILL REMAIN IN PLACE. AS IS TYPICAL OF CUTOFF LOWS...AREAS AROUND THE DISTURBANCE NOT AFFECTED BY CLOUDINESS WILL EXPERIENCE QUITE MILD WEATHER. THIS WILL BE TRUE FOR THE GREAT LAKES AND NEW ENGLAND TODAY AND TOMORROW. THE CUTOFF LOW TO OUR EAST WILL LOSE ITS INFLUENCE ACROSS THE LOWER OHIO VALLEY TODAY. TEMPERATURES SHOULD WARM NICELY THIS AFTERNOON UNDER MOSTLY SUNNY SKIES. WITH A VIRTUALLY NON-EXISTENT PRESSURE GRADIENT...WINDS WILL BE QUITE LIGHT AND VARIABLE. MOSTLY CLEAR SKIES WILL CONTINUE TONIGHT. PATCHY FOG IS QUITE POSSIBLE AGAIN TOMORROW MORNING. .LONG TERM (MONDAY NIGHT THROUGH SUNDAY)... TUESDAY THROUGH WEDNESDAY NIGHT... A SLOW MOVING COLD FRONT AND WEAK UPPER TROUGH WILL STRUGGLE TO MAKE INROADS INTO AN UPPER LEVEL RIDGE THAT WILL BE BUILDING OVER THE SOUTHEAST UNITED STATES AND THE CWA TUESDAY AND WEDNESDAY. CURRENT MODEL SOLUTIONS CONTINUE PREVIOUS TREND OF SLOWING FRONT DOWN AND PUSHING MAIN ENERGY INTO THE NORTHERN GREAT LAKES TUESDAY NIGHT AND WEDNESDAY...INSTEAD OF BRINGING IT INTO SOUTH CENTRAL INDIANA AND CENTRAL KENTUCKY. PER COORDINATION WITH NEIGHBORING OFFICES HAVE DRIED OUT THE FORECAST FOR TUESDAY NIGHT THROUGH WEDNESDAY NIGHT TO ACCOUNT FOR THIS. LATEST GFS AND NAM MODELS BOTH INDICATING UPPER RIDGE AXIS MAY BE DIRECTLY OVER TOP OF THE CWA LATE WEDNESDAY INTO THURSDAY...WHICH COULD MEAN DRY WEATHER FOR THURSDAY AND BEYOND ALSO. FOR NOW WILL NOT MAKE ANY CHANGES TO THE THURSDAY AND AFTER PERIOD AND MONITOR MODELS AND TRENDS AT A LATER TIME. PREVIOUS FORECAST DISCUSSION FOR THURSDAY THROUGH SUNDAY BELOW. THU THRU SUN... THIS FORECAST LEANS TOWARD THE GFS ENSEMBLES AND HPC WITH ASSISTS FROM THE ECMWF AND CANADIAN ENSEMBLES. CONSENSUS FROM THE ENSEMBLES AND HPC IS THAT A WARM FRONT WILL MOVE THRU OUR FA THU WITH A CDFNT APPROACHING AND MOVING THRU FRI NIGHT. UPR LEVEL TROF IN ARREARS OF FRONT TO APPROACH/MOVE THRU SAT. AT THIS POINT...THE GUIDANCE POINTS AT LATE FRI/FRI NIGHT AS THE BEST CHC FOR WIDESPREAD CONVECTIVE RAINFALL ASSOCIATED WITH FRONTAL APPROACH/PASSAGE. IT IS THIS PERIOD...WHERE WE WILL INSERT HIGHEST CHC POPS. FOR THU AFTN THRU FRI AFTN...WILL LEAVE 20 TO 40% POPS AS WMFNT REACHES UPR OH VLY BY EARLY FRI WITH CDFNT ACRS MO AT THAT TIME...AND MOISTURE TRANSPORT INCREASING ON SLY FLO. DEBATED ABOUT LEAVING SAT DRY PER OUR CURRENT FCST FAVORING THE ECMWF...BUT GENERALLY WENT WITH HPC/GFS ENSEMBLES WITH SMALL CHC POPS FOR POST FRONTAL SHOWERS AHEAD OF AFOREMENTIONED UPR LEVEL TROF. WILL END RAIN CHCS SAT NIGHT AND CONTINUE INTO SUN AS HIGH PRESSURE TRACKS FROM THE MID MS VLY INTO THE WESTERN OH VLY. TEMPS WILL BE WARMEST...ABOVE LATE APR SEASONAL NORMS...ON THU AND FRI WITH WMFROPA AND PRECDFNT. COOLEST TEMPS TO OCCUR SAT AND SUN NIGHT (GENERALLY 40 TO 45) OWING TO COLD ADVECTION SAT NIGHT AND RADIATIONAL COOLING SUN NIGHT AS 850 TEMPS DROP TO 1-5C. && .AVIATION (12Z TAFS)... DENSE FOG WILL CONTINUE AT LEX THROUGH 12 TO 13Z. FOG AT SDF AND BWG WILL BE LIGHTER...WITH VISIBILITES DROPPING ONLY TO 2 TO 3SM. AFTER FOG ERODES AFTER 13Z...EXPECT MOSTLY CLEAR SKIES AND LIGHT WINDS THIS AFTERNOON. FOG MAY REFORM EARLY TOMORROW...BUT WILL NOT BE NEARLY AS DENSE AS THIS MORNING`S. && .LMK WATCHES/WARNINGS/ADVISORIES... KY...NONE. IN...NONE. && $$ SHORT TERM...JSD LONG TERM....MACZKO/13 AVIATION.....JSD ky AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE PUEBLO CO 342 PM MDT MON APR 21 2008 .SHORT TERM... (TONIGHT AND TUESDAY) FIRE WEATHER CONDITIONS ARE AGAIN THE MAIN CONCERN. THE FRONT REMAINS BACKED UP ALONG THE SERN MTS AND IT APPEARS THAT THE AREAS OF FIRE ZONE 222 AND 225 WHERE I HAVE OBSERVATIONS ARE NOT CURRENTLY MEETING RED FLAG CRITERIA. HOWEVER ZONE 224...THE SAN LUIS VALLEY IS REACHING CRITERIA. THE 18Z NAM12 IS STILL INDICATING THAT MAYBE AROUND 3 PM THE WINDS BECOME WRLY AND GUSTY AND DRYING THINGS OUT...SO THERE IS STILL A CHANCE THAT ZONES 222 AND 225 WL REACH THE CRITICAL CRITERIA LATER. HOWEVER THE RUC13 KEEPS THE FRONT AND E TO SE WINDS ALONG THE SERN MTS...BUT SOME OF ZONE 222 DOES SEE THE FRONT MOVE A LITTLE EWRD WITH WRLY WINDS. WITH THE UNCERTAINTY WL NOT MAKE ANY CHANGES TO THE CURRENTLY RED FLAG WARNING. THE GRADIENT OVR THE AREA WL DECREASE FOR TUE WITH NO SHRTWV TROFS EXPECTED. AS A RESULT THE WINDS OVR THE AREA WL GENERALLY BE LIGHTER. SERLY LOW LEVEL WINDS OVR THE SERN PLAINS ARE EXPECTED TO DRAW IN A LITTLE MSTR AND THUS RH VALUES SHOULD BE A BIT HIGHER TUE...THUS THE FIRE WEATHER THREAT WL LESSEN. THE ONLY AREA THAT MAY AGAIN SEE CRITICAL FIRE WEATHER CONDITIONS TUE AFTERNOON AND EARLY EVENING...IS THE SAN LUIS VALLEY. IT STILL LOOKS LIKE AFTERNOON HUMIDITIES IN THE SAN LUIS VALLEY WL BE BELOW 15 PERCENT...AND IT SHOULD BE A BIT BREEZY. THE MAIN UNCERTAINTY FOR THE SAN LUIS VALLEY IS WHETHER THE WINDS WL BE STRONG ENOUGH TO WARRANT A RED FLAG WARNING...AT THIS TIME IT LOOKS LIKE WE COULD SEE GUSTS AROUND 25 MPH...SO WL GO WITH A FIRE WEATHER WATCH FOR THAT AREA. .LONG TERM... (TUESDAY NIGHT THROUGH MONDAY) ...POTENTIAL FOR HIGH IMPACT WEATHER ON WEDNESDAY...WITH FIRE WEATHER CONCERNS ACROSS THE WESTERN 2/3RDS OF THE FCST AREA...AND SEVERE THUNDERSTORMS ACROSS THE EAST... ...CONTINUATION OF DRY...BREEZY CONDITIONS FOR THURSDAY WITH ANOTHER RED FLAG DAY POSSIBLE... LOTS OF CONCERNS IN THE SHORTER TERM (ESP WEDNESDAY)...SO FOCUS OF DISCUSSION WILL BE DURING THIS TIME FRAME. DRY LINE WILL BE BACKING INTO THE EASTERN PLAINS TUESDAY NIGHT THANKS TO SERLY LOW LVL JET...WITH SFC DEW POINTS CLIMBING INTO THE LOWER 50S ALONG THE BORDER TOWARDS 12Z. WIDESPREAD STRATUS WILL DEVELOP ACROSS THE EASTERN PLAINS AFTER 06Z. THE INCREASE IN MOISTURE IS GOOD FOR FIRE WEATHER CONCERNS...HOWEVER BY AFTN/EVENING...NEXT SHORTWAVE/ASSOC UPPER LVL JET WILL BE MOVING ACROSS THE AREA IN SW FLOW ALOFT. SFC DRY LINE WILL SET UP SOMEWHERE ACROSS THE SE CO PLAINS DURING THE AFTN...WITH NAM12 RETREATING DRYLINE EASTWARD TO BETWEEN KLHX AND KLAA BY 21Z. 12Z NAM12 SHOWED UP TO 1800 J/KG OF CAPE ALONG/EAST OF THE DRY LINE...WITH DEEP LAYER SHEARS RUNNING AROUND 40-50 KTS. THUS...CONCERN FOR THE EASTERN COUNTIES WILL BE POTENTIAL FOR SEVERE WEATHER WITH INGREDIENTS IN PLACE FOR SUPERCELL THUNDERSTORMS. MOST LIKELY THREATS WILL BE HAIL AND DAMAGING WIND GUSTS. BUT COULDN`T RULE OUT A POSSIBLE TORNADO IF LOW LVL HELICITIES BECOME ENHANCED ALONG THE DRY LINE. MEANWHILE OUT WEST...SOUTHWEST FLOW WILL MIX OUT WHATEVER MEAGER LOW LVL MOISTURE IS IN PLACE DURING THE OVERNIGHT HOURS...WITH GUSTY SOUTHWEST WINDS SPREADING FROM THE HIGHER TERRAIN INTO THE VALLEYS AND LOWER EASTERN SLOPES/I-25 CORRIDOR DURING THE MORNING. RH`S DROP BELOW 15% WEST OF THE DRY LINE...WITH WIND GUSTS UP TO 40-50 MPH POSSIBLE. VERY UNSTABLE AND DRY ALOFT...SO HAINES INDICES END UP AROUND 6. ALL THESE PARAMETERS LEAD TO A HIGH POTENTIAL FOR CRITICAL FIRE WEATHER PARAMETERS FOR WEDNESDAY...WITH ERRATIC FIRE BEHAVIOR AND EXPLOSIVE RATES OF SPREAD POSSIBLE BELOW 8000 FEET WHERE FUELS ARE DRY. DUE TO THE MAGNITUDE OF THIS POTENTIAL EVENT...HAVE ISSUED A FIRE WEATHER WATCH FOR AREAS ALONG/WEST OF THE DRY LINE FOR WED...BASICALLY ALONG AND WEST OF A LINE FROM ROUGHLY KLHX TO KIM. THERE IS MUCH UNCERTAINTY ON THE EXACT POSITION OF THE DRY LINE WHICH WILL IMPACT HOW FAR WEST THE SEVERE THUNDERSTORM POTENTIAL WILL EXIST...AND HOW FAR EAST THE CRITICAL FIRE WEATHER PARAMETERS WILL SET UP. THERE WILL LIKELY BE A TIGHT GRADIENT BETWEEN THESE TWO EXTREMES. MOISTURE INCREASES ACROSS THE CENTRAL MTS DURING WED AFTERNOON...SO COULD SEE SOME ISOLATED SNOW SHOWERS. EASTERN MTS LOOK TOO DRY AND HAVE REMOVED THE LOW GRADE POPS FOR THIS AREA. DRY LINE RETREATS BACK WESTWARD DURING THE EVENING...THEN SHORTWAVE MOVES THROUGH OVERNIGHT WITH DRY LINE ADVANCING EASTWARD INTO KS BY EARLY THURS MORNING. THIS SETS UP THE SCENARIO FOR MORE POTENTIAL REF FLAG CONDITIONS THURS...WITH YET ANOTHER SHORTWAVE/UPPER JET MOVING ACROSS THE AREA AND VERY DRY LOW LAYERS. HIGHEST THREAT AREA WILL BE ACROSS THE WESTERN 2/3RDS OF THE FCST AREA. ASIDE FROM SOME ISOLATED SNOW SHOWERS ACROSS THE CENTRAL MTS THURS AFTN/EVENING...REST OF THE FCST AREA WILL STAY DRY. SHORTWAVE PASSES BY TO THE NORTH THURS NIGHT SENDING A COLD FRONT THROUGH THE SE PLAINS. THIS SHOULD BRING RELIEF TO THE FIRE WEATHER ZONES ALONG/EAST OF THE SE MTS. MEANWHILE...SW FLOW ALOFT MAY KEEP THE SAN LUIS VALLEY NEAR RED FLAG CONDITIONS. ANOTHER SHORTWAVE MOVES THROUGH SAT NIGHT SENDING ANOTHER COLD FRONT AND PERHAPS A BETTER CHANCE FOR PCPN ACROSS THE EAST FRI NIGHT INTO SAT. MODELS HAVE BEEN FLIP FLOPPING WITH THE STRENGTH/TRACK OF THIS SYSTEM...SO NOT QUITE READY TO BUY OFF ON IT YET. THE MORE CONSISTENT ECMWF IS WEAKER AND DRIER WITH THIS SYSTEM THAN THE GFS. THUS HAVE NOT MADE ANY SIGNIFICANT CHANGES TO THE REMAINDER OF THE EXTENDED. -KT && .AVIATION...THE MTS AND HIGH VALLEYS WILL SEE SOME STRONG WIND GUSTS UNTIL AROUND 02Z...AND THEN THE WINDS SHOULD GENERALLY DECREASE. EXPECT VFR CONDITIONS ALL AREAS. && .PUB WATCHES/WARNINGS/ADVISORIES... FIRE WEATHER WATCH FROM WEDNESDAY MORNING THROUGH WEDNESDAY EVENING FOR COZ222-224>233. RED FLAG WARNING UNTIL 9 PM MDT THIS EVENING FOR COZ222-224-225. FIRE WEATHER WATCH FROM TUESDAY AFTERNOON THROUGH TUESDAY EVENING FOR COZ224. && $$ 28/31 co AREA FORECAST DISCUSSION...CORRECTED NATIONAL WEATHER SERVICE TAUNTON MA 419 PM EDT MON APR 21 2008 .SYNOPSIS... A RATHER STAGNANT PATTERN WILL KEEP DRY WEATHER WITH US FOR MOST OF THE NEXT 7 DAYS WITH ABOVE NORMAL TEMPERATURES AND BELOW NORMAL PRECIPITATION. && .NEAR TERM /UNTIL 6 AM TUESDAY MORNING/... HIGH PRESSURE WILL COVER THE FORECAST AREA TONIGHT. DRY CONDITIONS WILL ALLOW FOR GOOD RADIATIONAL COOLING CONDITIONS ACROSS THE INTERIOR. MAIN FORECAST CHALLENGE WILL BE THE RE-DEVELOPMENT...TIMING AND EXPANSION OF STRATUS FROM THE COASTAL WATERS ACROSS THE COASTAL PLAIN. THE 12Z NAM BUFKIT RELATIVE HUMIDITY CROSS SECTIONS HINT AT THIS RE-DEVELOPMENT MAINLY FROM 06Z TO 12Z TONIGHT ALONG AND EAST OF INTERSTATE 95...WHILE NEITHER THE GFS OR THE RUC13 INDICATE THIS TREND. OVERALL GIVEN THE PRESENCE OF THE SURFACE HIGH AND LIGHT EASTERLY FLOW OFF THE OCEAN...WITH A STRENGTHENING LOW LEVEL INVERSION TONIGHT... DECIDED TO FOLLOW THE NAM AT THIS TIME. && .SHORT TERM /6 AM TUESDAY MORNING THROUGH TUESDAY NIGHT/... TUESDAY...MORNING COASTAL LOW CLOUDS OR FOG PATCHES WILL GIVE WAY TO A MOSTLY SUNNY DAY...WITH WARMING TEMPERATURES ESPECIALLY ACROSS THE INTERIOR. SOUTHEAST TO SOUTH BOUNDARY LAYER WIND FLOW WILL FAVOR WARMEST TEMPERATURES ACROSS THE NORTHWEST INTERIOR. 850 MILLIBAR TEMPERATURES WILL RANGE FROM +8 TO +9 CELSIUS. EXPECT HIGHS IN THE LOWER TO MID 70S INLAND...COOLER ALONG THE COAST TUESDAY NIGHT...COOL AND DRY CONDITIONS WILL PREVAIL. HOWEVER THERE IS A CHANCE SOME STRATUS MAY REFORM UNDERNEATH THE SURFACE HIGH AND LOW LEVEL INVERSION ALONG THE SOUTH COAST. DID NOT STRAY FAR FROM MOS TEMPERATURE GUIDANCE. && .LONG TERM /WEDNESDAY THROUGH MONDAY/... PATTERN REMAINS FAIRLY BLOCKY FOR THE NEXT 7 DAYS. WHEN THE PATTERN IS DOMINATED BY BLOCKING...THIS CAN EITHER MEAN BAD AND GOOD NEWS DEPENDING WHERE YOU ARE. IN THE CASE OF SNE THIS IS GOOD NEWS SINCE WE WILL BE DOMINATED BY RIDGING FOR MUCH OF THE NEXT 7 DAYS. WEDNESDAY COULD CERTAINLY BE THE PICK OF THE NEXT SEVERAL DAYS WITH MOSTLY SUNNY SKIES AND GOOD MIXING. THIS WILL AID IN BRINGING TEMPS UP AROUND 80 FOR MOST OF THE REGION AWAY FROM THE IMMEDIATE COAST. SHORT WAVE MOVES ACROSS NORTHERN NEW ENGLAND WED NIGHT. THIS COULD BRING A COUPLE OF BRIEF SHOWERS ACROSS NORTHERN ZONES...BUT THAT/S ABOUT IT. WILL STICK CLOSE TO THE GFS/GFS ENS FOR THURS THROUGH THE WEEKEND. THIS MEANS A MAINLY DRY FORECAST WITH ANY SIGNIFICANT PRECIP PROBABLY HOLDING OFF TIL AFTER THE WEEKEND IF IT OCCURS AT ALL. ONSHORE FLOW MAY MAKE IT A BIT COOL AT TIMES...ALONG WITH PERIODS OF STRATUS/DRIZZLE BUT THAT REMAINS TO BE SEEN. && .AVIATION /20Z MONDAY THROUGH SATURDAY/... TONIGHT...VFR. HOWEVER IFR CEILINGS EXPECTED AGAIN FROM BOS-PVD-FMH-HYA- ACK. STRATUS EXPANDS FROM NE TO SW FROM 02Z TO 06Z. NOT HIGHLY CONFIDENT ON THE EXACT TIMING OR AREAL COVERAGE. THE 06Z TO 12Z TIMEFRAME SHOULD EXPERIENCE THE MOST WIDESPREAD IFR CEILINGS IN THIS AREA. TUESDAY...VFR. EXCEPT VFR AFT 14Z SOME COASTAL TERMINALS. TUE NIGHT...VFR. POSSIBLE IFR CEILINGS IN STRATUS AFT 06Z SOUTH COAST. OUTLOOK...WEDNESDAY THROUGH SATURDAY... VFR CONDITIONS ARE EXPECTED FOR MUCH OF THE EXTENDED PORTION OF THE FORECAST. HOWEVER...THERE MAY BE PERIODS OF MVFR/IFR CONDITIONS LATE AT NIGHT AND EARLY IN THE MORNING DURING PERIODS OF ONSHORE FLOW. LITTLE IF ANY PRECIPITATION IS FORECAST && .MARINE... TODAY...5 FOOT EASTERLY SWELLS CONTINUE ACROSS THE FAR SOUTHERN OUTER WATERS. WILL CONTINUE THE SCA FOR HAZARDOUS SEAS IN THIS REGION THROUGH 12Z TUE. TUE AND TUE NIGHT...E SWELL SUBSIDES. WINDS AND SEAS EXPECTED TO REMAIN BELOW SCA CRITERIA. OUTLOOK...WEDNESDAY THROUGH SATURDAY... RELATIVELY TRANQUIL CONDITIONS ARE EXPECTED FOR MOST OF THE EXTENDED PERIOD. THERE MAY BE A PERIOD OF SWLY SCA WINDS AND SEAS WED NIGHT AHEAD OF THE COLD FRONT. THERE MAY ALSO BE A PERIOD OF MARGINAL SCA CONDITIONS THURSDAY INTO THURSDAY NIGHT AS LOW PRESSURE DEVELOPS OFFSHORE. && .FIRE WEATHER... DRY PATTERN CONTINUES...AS MOST OF THE REGION HAS NOT SEEN ANY MEASURABLE RAINFALL IN THE PAST 10 DAYS. LOW AFTERNOON RELATIVE HUMIDITY FROM 20 TO 30 PERCENT WILL OCCUR TUESDAY AWAY FROM THE COAST. SURFACE WINDS WILL BE WELL BELOW THE THRESHOLDS FOR ANY FIRE WEATHER HEADLINES. LITTLE IN THE WAY OF WETTING RAINFALL IS EXPECTED THROUGH THE EXTENDED TIMEFRAME. && .HYDROLOGY... THE FLOOD WARNING CONTINUES FOR THE CONNECTICUT RIVER AT MIDDLETOWN WHICH IS IN MINOR FLOOD. THE RIVER WILL RISE ONE HALF FOOT TO ONE FOOT ABOVE FLOOD STAGE AND CREST LATE TUESDAY. THE RIVER IS EXPECTED TO REMAIN IN FLOOD THROUGH WEDNESDAY. A FLOOD WARNING ALSO CONTINUES FOR THE CONNECTICUT RIVER AT HARTFORD. DESPITE THE RECENT STRETCH OF DRY WEATHER...SNOWMELT OVER NORTHERN NEW ENGLAND AND TIDAL FLUCTUATIONS WILL ALLOW THE RIVER TO SUSTAIN MINOR FLOOD TONIGHT THROUGH WEDNESDAY AFTERNOON. PLEASE SEE THE LATEST FLOOD STATEMENTS AND RIVER FORECASTS FOR MORE DETAILS. && .BOX WATCHES/WARNINGS/ADVISORIES... CT...NONE. MA...NONE. NH...NONE. RI...NONE. MARINE...SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS UNTIL 8 AM EDT TUESDAY FOR ANZ254-255. && $$ SYNOPSIS...EKSTER NEAR TERM...STRAUSS SHORT TERM...STRAUSS LONG TERM...EKSTER AVIATION...EKSTER/STRAUSS MARINE...EKSTER/STRAUSS FIRE WEATHER... HYDROLOGY... ct AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WICHITA KS 315 PM CDT MON APR 21 2008 .DISCUSSION... FORECAST CONCERNS...CONVECTIVE CHANCES/TRENDS FOR MUCH OF THE WEEK. LARGE SCALE UPPER LOW/VORTEX ACROSS WESTERN CANADA INTO THE PACIFIC NORTHWEST/NORTHERN ROCKIES WILL CONTINUE TO INFLUENCE THE WEATHER ACROSS THE AREA MUCH OF THIS WEEK...EJECTING PERIODIC SHORTWAVES ACROSS THE CENTRAL PLAINS. FIRST SUCH FEATURE WAS MOVING ACROSS THE FOUR CORNERS AREA AT EARLY AFTERNOON...AND WILL EJECT ACROSS COLORADO AND NEBRASKA TONIGHT. WHILE SIMILAR ON THE SUFFICIENT DEEP LAYER 0-6KM SHEAR OF 35-40KTS THIS EVENING IN THE WARM SECTOR ACROSS THE FLINT HILLS AND SOUTHEAST KANSAS...THE SHORT RANGE MODELS DIFFER ON DEGREE OF INSTABILITY. THE 18Z RUC MAY BE THE CLOSEST TO REALITY IN THE FIRST 6 TO 9 HOURS...SHOWING ABOUT 2000J/KG OF ML CAPE ACROSS THIS AREA TOWARD 00Z. HOWEVER...THE CAP STRENGTH THOUGH WEAKENING TO ABOUT 50-75 J/KG...MAY STILL BE ENOUGH TO SUPPRESS SURFACE BASED CONVECTION. THAT SAID...CHANCES APPEAR TO BE RELATIVELY BETTER CLOSER TO MIDNIGHT...IN CONCERT WITH EJECTING UPPER TROF AND BETTER ELEVATED LOW LEVEL MOISTURE CONVERGENCE JUST NORTH OF SURFACE FRONT. EVEN THE MORE CONSERVATIVE NAM SHOWS ABOUT 1000J/KG OF ELEVATED CAPE WITH WEAKENING CIN ACROSS PORTIONS OF SOUTH CENTRAL/SOUTHEAST KANSAS INTO THE EARLY MORNING PREDAWN HOURS. ONLY SLIGHT TWEAKS IN THIS REGARD TO GOING POP FORECAST...AND WILL KEEP MENTION OF MARGINALLY SEVERE HAIL/WIND IN HAZARDOUS WEATHER OUTLOOK. LOW LEVEL MOISTURE ONLY GETS SHUNTED TO THE OKLAHOMA BORDER ON TUESDAY IN WAKE OF DEPARTING TROF. DESPITE LACK OF SIGNIFICANT FORCING WILL KEEP SLIGHT POPS ALONG THE OKLAHOMA BORDER COUNTIES WHICH WILL RESIDE JUST NORTH OF SURFACE FRONT AND BETTER INSTABILITY TO THE SOUTH. AS NEXT UPPER TROF DEEPENS A BIT ALONG THE PACIFIC NORTHWEST COAST THRU MID-WEEK...TRANSIENT SHORTWAVES OF VARYING STRENGTH WILL LIFT OUT ACROSS THE PLAINS. THE INITIAL LOW LEVEL MOISTURE FLUX AND RESULTANT ELEVATED INSTABILITY WILL LEAD TO AT LEAST SLIGHT CHANCES FOR CONVECTION LATER TUESDAY NIGHT...WITH INCREASING CHANCES INTO WEDNESDAY NIGHT. NOISE IN THE MODELS THIS FAR OUT MAKE IT HARD TO PIN DOWN RELATIVE CHANCES ACROSS ANY GIVEN AREA...SO WILL SHOW UNIFORM MODEST CHANCE POPS ACROSS THE AREA. A MORE VIGOROUS UPPER TROF WILL MOVE ACROSS THE NORTHERN PLAINS ON THURSDAY/THURSDAY NIGHT...DRIVING A MODERATE STRENGTH COLD FRONT ACROSS THE AREA BY FRIDAY MORNING. WILL SHOW HIGHEST POPS ACROSS MUCH OF THE AREA THURSDAY NIGHT...WITH DRYING BEHIND FRONT BY LATER FRIDAY. THE GUIDANCE FROM HPC AND LATEST INTER-OFFICE FORECAST CONSENSUS WAS TO LEAN TOWARD THE ECMWF FOR THE OUTER PERIODS THROUGH THE WEEKEND AND INTO EARLY NEXT WEEK. THIS WILL RESULT IN SHOWING A MORE LIMITED MOISTURE RETURN WITH SURFACE COLD FRONT ON SUNDAY WITH UPPER ENERGY MORE PHASED WITH LONGWAVE ACROSS THE GREAT LAKES...INSTEAD OF THE GFS`S MORE CUTOFF UPPER LOW SCENARIO ACROSS KANSAS BY SUNDAY NIGHT. THEREFORE WILL GO DRY FOR MONDAY PER THE ECMWF. DARMOFAL && .AVIATION... FOR 18Z TAFS...MAIN AVIATION CONCERNS WILL BE LOW CLOUDS AND STORM CHANCES. A SURFACE FRONT IS CURRENTLY STRETCHING FROM NEAR MHK TO KICT. RELATIVELY LOWER CLOUDS ARE SITUATED EAST OF THIS BOUNDARY AFFECTING KCNU. CONFIDENCE IS HIGH THAT THESE CLOUDS WILL CONTINUE TO AFFECT SE KS THROUGH THE EVENING HOURS. WHILE THEY ARE CURRENTLY JUST ABOVE MVFR CIGS...AM EXPECTING THEM TO LOWER THROUGH THE OVERNIGHT HOURS. CONFIDENCE IN CLOUD COVER DECREASES GREATLY FOR THE REMAINDER OF THE FORECAST AREA. THE SURFACE FRONT IS EXPECTED TO STALL OUT LATE THIS AFTERNOON INTO THE EVENING HOURS WITH MOISTURE STREAMING NORTH AND INTERACTING WITH THE FRONT. CURRENT THINKING IS THAT SOME ADDITIONAL LOW CLOUDS MAY DEVELOP BACK TO THE WEST AND ENCOMPASS MOST OF THE AREA AFTER SUNSET. HOWEVER CONFIDENCE IS LOW IN THIS OCCURRING. KCNU WILL HAVE THE BEST STORM CHANCES OVERNIGHT WITH MOISTURE CONTINUING TO WORK NORTH INTO SE KS. ANY STORM THAT DEVELOPS OVERNIGHT OVER SE KS WILL HAVE THE POTENTIAL TO BE SEVERE. LAWSON && .PRELIMINARY POINT TEMPS/POPS... WICHITA-KICT 56 72 57 78 / 20 10 10 30 HUTCHINSON 53 73 56 77 / 20 10 10 30 NEWTON 55 72 56 77 / 20 10 10 30 ELDORADO 57 71 57 77 / 30 10 10 30 WINFIELD-KWLD 59 73 59 78 / 30 20 20 30 RUSSELL 46 72 53 76 / 10 10 10 30 GREAT BEND 48 72 55 76 / 20 10 20 30 SALINA 50 73 54 77 / 20 10 10 30 MCPHERSON 52 73 56 77 / 20 10 10 30 COFFEYVILLE 61 75 59 79 / 40 20 20 30 CHANUTE 59 74 57 78 / 40 20 10 30 IOLA 59 73 56 78 / 40 10 10 30 PARSONS-KPPF 60 75 58 79 / 40 20 20 30 && .ICT WATCHES/WARNINGS/ADVISORIES...NONE. && $$ ks AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WICHITA KS 1244 PM CDT MON APR 21 2008 .AVIATION... FOR 18Z TAFS...MAIN AVIATION CONCERNS WILL BE LOW CLOUDS AND STORM CHANCES. A SURFACE FRONT IS CURRENTLY STRETCHING FROM NEAR MHK TO KICT. RELATIVELY LOWER CLOUDS ARE SITUATED EAST OF THIS BOUNDARY AFFECTING KCNU. CONFIDENCE IS HIGH THAT THESE CLOUDS WILL CONTINUE TO AFFECT SE KS THROUGH THE EVENING HOURS. WHILE THEY ARE CURRENTLY JUST ABOVE MVFR CIGS...AM EXPECTING THEM TO LOWER THROUGH THE OVERNIGHT HOURS. CONFIDENCE IN CLOUD COVER DECREASES GREATLY FOR THE REMAINDER OF THE FORECAST AREA. THE SURFACE FRONT IS EXPECTED TO STALL OUT LATE THIS AFTERNOON INTO THE EVENING HOURS WITH MOISTURE STREAMING NORTH AND INTERACTING WITH THE FRONT. CURRENT THINKING IS THAT SOME ADDITIONAL LOW CLOUDS MAY DEVELOP BACK TO THE WEST AND ENCOMPASS MOST OF THE AREA AFTER SUNSET. HOWEVER CONFIDENCE IS LOW IN THIS OCCURRING. KCNU WILL HAVE THE BEST STORM CHANCES OVERNIGHT WITH MOISTURE CONTINUING TO WORK NORTH INTO SE KS. ANY STORM THAT DEVELOPS OVERNIGHT OVER SE KS WILL HAVE THE POTENTIAL TO BE SEVERE. LAWSON && .PREV DISCUSSION... /ISSUED 1130 AM CDT MON APR 21 2008/ UPDATE... UPDATED TO MAKE CHANGES TO CLOUD COVER AND DEWPOINTS. SURFACE FRONT CURRENTLY EXTENDS FROM KMHK TO NEAR KICT WITH CLEARING AND DRY ADVECTION TAKING PLACE WEST OF THIS FRONT. EAST OF THE BOUNDARY DEWPOINTS CONTINUE TO RISE INTO THE LOW 60S WITH EVEN JUICIER AIR SOUTH OF THE OK BORDER. LAPS AND RUC DATA...ALONG WITH VIS SATELLITE IMAGERY...INDICATES THAT A STRONG CAP IS CURRENTLY IN PLACE EAST OF THE FRONT AND THIS LOOKS TO STAY IN PLACE FOR AT LEAST THE NEXT 4 HOURS. THIS WILL LIMIT ANY CONVECTIVE DEVELOPMENT UNTIL AFTER 4PM AND MORE LIKELY TOWARD SUNSET. CONVECTIVE INITIATION WILL BE HIGHLY DEPENDANT ON CLOUD OVER OVER NORTH CENTRAL OK/SOUTH CENTRAL KS. MAIN REASON FOR UPDATE WAS TO TWEAK CLOUD COVER AND DEWPOINTS TO KEEP UP WITH CURRENT TRENDS. LAWSON PREV DISCUSSION... /ISSUED 634 AM CDT MON APR 21 2008/ AVIATION... COLD FRONT MOVING THROUGH KRSL AT THIS TIME...WITH FRONT EXPECTED TO MAKE GOOD PROGRESS THIS MORNING THROUGH KSLN/KHUT...WITH MIDDAY FRONTAL PASSAGE AT KICT. FRONT NOT EXPECTED AT KCNU UNTIL LATE THIS EVENING. BASED ON IFR OBSERVATIONS AT KPTT AND K9K8...INCLUDED A TEMPORARY IFRU AT KHUT AS RELATIVE COOL MOIST AIR IMPINGES ON THE WARMER/MOIST AIR AT KHUT. APPEARS THAT QUITE WARM TEMPERATURES ALOFT SHOULD INHIBIT THUNDERSTORM DEVELOPMENT THIS AFTERNOON...AND LIMITED AREAL COVERAGE ANTICIPATED IN THE VICINITY OF FRONT TONIGHT. THIS PRECLUDED MENTIONING TS/VCTS AT KICT/KCNU...BUT HAVE INCLUDED CB FOR KCNU. -HOWERTON PREV DISCUSSION... /ISSUED 303 AM CDT MON APR 21 2008/ DISCUSSION... MAIN FORECAST CONCERNS ARE PRECIPITATION CHANCES THROUGH THURSDAY AND TEMPERATURES DURING THE SAME TIME. TODAY-TONIGHT: STRATOCUMULUS HAS BEEN STEADILY INCREASING OVERNIGHT ACROSS OKLAHOMA INTO SOUTH CENTRAL AND SOUTHEAST KANSAS. THE BIG QUESTION IS WHETHER OR NOT THESE CLOUDS ARE GOING TO CLEAR THIS AFTERNOON TO DESTABILIZE THE ATMOSPHERE AND GET SOME THUNDERSTORMS. THE 21/00Z NAM HAS INITIALIZED MUCH BETTER (ALTHOUGH NOT GREAT) WITH MOISTURE...AND IT PROCEEDS TO KEEP THE STRATOCUMULUS AROUND THROUGH THE AFTERNOON AND EVENING. THE NAM ALSO SHOWS A VERY STRONG CAP AT AROUND 750 TO 800MB...WHICH SURFACE TEMPERATURES WOULD HAVE TO CLIMB INTO THE LOWER TO MIDDLE 80S ACROSS SOUTH CENTRAL AND SOUTHEAST KANSAS RESPECTIVELY TO BREAK. THEREFORE WE REMOVED PRECIPITATION CHANCES FOR THE AFTERNOON...BUT KEPT THEM FOR THE EVENING AND OVERNIGHT HOURS FOR THE EASTERN PART OF THE FORECAST AREA. THE STORMS DURING THE EVENING AND OVERNIGHT ARE NOT EXPECTED TO BE SEVERE...HOWEVER THERE COULD BE SOME STRONG STORMS. THE SURFACE FRONT WILL COME THROUGH CENTRAL KANSAS THIS MORNING...AND IS EXPECTED TO STALL FOR AWHILE THIS AFTERNOON SOMEWHERE ACROSS SOUTH CENTRAL KANSAS BEFORE ANOTHER PUSH COMES FROM THE NEXT PIECE OF ENERGY IN THE EVENING. TEMPERATURES AHEAD OF THE FRONT ARE EXPECTED TO BE IN THE LOWER 80S...AND EVEN IN CENTRAL KANSAS COULD CLIMB HIGHER THAN EXPECTED WITH NORTHWEST WINDS PROVIDING DOWNSLOPE FLOW. TUESDAY-WEDNESDAY: PRECIPITATION MOVES OUT ON TUESDAY AS SURFACE HIGH PRESSURE PASSES BY OVER NEBRASKA. THIS WILL BE A BREAK IN STORMY WEATHER BEFORE THE NEXT SYSTEM BRINGS PRECIPITATION CHANCES AGAIN STARTING WEDNESDAY. TEMPERATURES TUESDAY AND WEDNESDAY SHOULD BE A FEW DEGREES ABOVE NORMAL FOR THIS TIME OF YEAR...WITH PLENTY OF SUNSHINE ESPECIALLY ON TUESDAY. THURSDAY-SUNDAY: THUNDERSTORM CHANCES CONTINUE ON THURSDAY INTO FRIDAY AS THE UPPER TROUGH MOVES THROUGH THE CENTRAL PART OF THE COUNTRY. THURSDAY LOOKS TO BE THE WARMEST DAY BEFORE TEMPERATURES RETURN TO NORMAL FOR THE WEEKEND. AT LEAST THAT`S THE WAY IT LOOKS RIGHT NOW. SCHRECK AVIATION...06Z TAFS [RSL/SLN/HUT/ICT/CNU] MAIN CONCERN WILL BE POTENTIAL FOR MVFR CIGS. COLD FRONT WAS ENTERING NORTHWESTERN NEBRASKA LATE THIS EVENING AND WILL APPROACH CENTRAL KS EARLY MON AM. THE FRONT WILL SLOW DOWN CONSIDERABLY OVER S-CNTRL/SERN KS MON/MON EVE. LEADING EDGE OF GULF MOISTURE WAS INTO WESTERN OKLAHOMA LATE THIS EVE...AND PROGGED TO REACH CENTRAL/SOUTH CENTRAL KS OVERNIGHT INTO MON AM. THIS SURGE OF GULF MOISTURE WILL LIKELY BE ACCOMPANIED BY MVFR CIGS WHICH COULD LAST INTO MON PM AS LOW-LEVEL MOISTURE REMAINS TRAPPED BENEATH INVERSION. DEPENDING ON HOW MUCH IF ANY SUN/HEATING WE GET MON PM...THERE IS A CHANCE FOR AN ISOLD TS OR TWO ACROSS S-CNTRL/SERN KS. GIVEN INITIATION AND COVERAGE CONCERNS...WILL LEAVE OUT ANY MENTION OF TS AT THIS JUNCTURE. JMC && .PRELIMINARY POINT TEMPS/POPS... WICHITA-KICT 76 53 74 54 / 10 20 10 0 HUTCHINSON 71 47 71 51 / 10 10 10 0 NEWTON 74 51 71 52 / 10 20 10 0 ELDORADO 77 55 74 52 / 10 30 10 0 WINFIELD-KWLD 80 57 74 55 / 10 30 10 10 RUSSELL 71 40 71 46 / 0 10 10 0 GREAT BEND 72 41 71 48 / 0 10 10 0 SALINA 66 43 72 49 / 10 10 10 0 MCPHERSON 69 47 71 49 / 10 20 10 0 COFFEYVILLE 81 60 76 57 / 10 40 30 10 CHANUTE 80 59 75 53 / 10 40 30 10 IOLA 79 58 75 52 / 10 40 30 0 PARSONS-KPPF 80 60 76 56 / 10 40 30 10 && .ICT WATCHES/WARNINGS/ADVISORIES... NONE. && $$ ks AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WICHITA KS 1130 AM CDT MON APR 21 2008 .UPDATE... UPDATED TO MAKE CHANGES TO CLOUD COVER AND DEWPOINTS. SURFACE FRONT CURRENTLY EXTENDS FROM KMHK TO NEAR KICT WITH CLEARING AND DRY ADVECTION TAKING PLACE WEST OF THIS FRONT. EAST OF THE BOUNDARY DEWPOINTS CONTINUE TO RISE INTO THE LOW 60S WITH EVEN JUICIER AIR SOUTH OF THE OK BORDER. LAPS AND RUC DATA...ALONG WITH VIS SATELLITE IMAGERY...INDICATES THAT A STRONG CAP IS CURRENTLY IN PLACE EAST OF THE FRONT AND THIS LOOKS TO STAY IN PLACE FOR AT LEAST THE NEXT 4 HOURS. THIS WILL LIMIT ANY CONVECTIVE DEVELOPMENT UNTIL AFTER 4PM AND MORE LIKELY TOWARD SUNSET. CONVECTIVE INITIATION WILL BE HIGHLY DEPENDANT ON CLOUD OVER OVER NORTH CENTRAL OK/SOUTH CENTRAL KS. MAIN REASON FOR UPDATE WAS TO TWEAK CLOUD COVER AND DEWPOINTS TO KEEP UP WITH CURRENT TRENDS. LAWSON && .PREV DISCUSSION... /ISSUED 634 AM CDT MON APR 21 2008/ AVIATION... COLD FRONT MOVING THROUGH KRSL AT THIS TIME...WITH FRONT EXPECTED TO MAKE GOOD PROGRESS THIS MORNING THROUGH KSLN/KHUT...WITH MIDDAY FRONTAL PASSAGE AT KICT. FRONT NOT EXPECTED AT KCNU UNTIL LATE THIS EVENING. BASED ON IFR OBSERVATIONS AT KPTT AND K9K8...INCLUDED A TEMPORARY IFRU AT KHUT AS RELATIVE COOL MOIST AIR IMPINGES ON THE WARMER/MOIST AIR AT KHUT. APPEARS THAT QUITE WARM TEMPERATURES ALOFT SHOULD INHIBIT THUNDERSTORM DEVELOPMENT THIS AFTERNOON...AND LIMITED AREAL COVERAGE ANTICIPATED IN THE VICINITY OF FRONT TONIGHT. THIS PRECLUDED MENTIONING TS/VCTS AT KICT/KCNU...BUT HAVE INCLUDED CB FOR KCNU. -HOWERTON PREV DISCUSSION... /ISSUED 303 AM CDT MON APR 21 2008/ DISCUSSION... MAIN FORECAST CONCERNS ARE PRECIPITATION CHANCES THROUGH THURSDAY AND TEMPERATURES DURING THE SAME TIME. TODAY-TONIGHT: STRATOCUMULUS HAS BEEN STEADILY INCREASING OVERNIGHT ACROSS OKLAHOMA INTO SOUTH CENTRAL AND SOUTHEAST KANSAS. THE BIG QUESTION IS WHETHER OR NOT THESE CLOUDS ARE GOING TO CLEAR THIS AFTERNOON TO DESTABILIZE THE ATMOSPHERE AND GET SOME THUNDERSTORMS. THE 21/00Z NAM HAS INITIALIZED MUCH BETTER (ALTHOUGH NOT GREAT) WITH MOISTURE...AND IT PROCEEDS TO KEEP THE STRATOCUMULUS AROUND THROUGH THE AFTERNOON AND EVENING. THE NAM ALSO SHOWS A VERY STRONG CAP AT AROUND 750 TO 800MB...WHICH SURFACE TEMPERATURES WOULD HAVE TO CLIMB INTO THE LOWER TO MIDDLE 80S ACROSS SOUTH CENTRAL AND SOUTHEAST KANSAS RESPECTIVELY TO BREAK. THEREFORE WE REMOVED PRECIPITATION CHANCES FOR THE AFTERNOON...BUT KEPT THEM FOR THE EVENING AND OVERNIGHT HOURS FOR THE EASTERN PART OF THE FORECAST AREA. THE STORMS DURING THE EVENING AND OVERNIGHT ARE NOT EXPECTED TO BE SEVERE...HOWEVER THERE COULD BE SOME STRONG STORMS. THE SURFACE FRONT WILL COME THROUGH CENTRAL KANSAS THIS MORNING...AND IS EXPECTED TO STALL FOR AWHILE THIS AFTERNOON SOMEWHERE ACROSS SOUTH CENTRAL KANSAS BEFORE ANOTHER PUSH COMES FROM THE NEXT PIECE OF ENERGY IN THE EVENING. TEMPERATURES AHEAD OF THE FRONT ARE EXPECTED TO BE IN THE LOWER 80S...AND EVEN IN CENTRAL KANSAS COULD CLIMB HIGHER THAN EXPECTED WITH NORTHWEST WINDS PROVIDING DOWNSLOPE FLOW. TUESDAY-WEDNESDAY: PRECIPITATION MOVES OUT ON TUESDAY AS SURFACE HIGH PRESSURE PASSES BY OVER NEBRASKA. THIS WILL BE A BREAK IN STORMY WEATHER BEFORE THE NEXT SYSTEM BRINGS PRECIPITATION CHANCES AGAIN STARTING WEDNESDAY. TEMPERATURES TUESDAY AND WEDNESDAY SHOULD BE A FEW DEGREES ABOVE NORMAL FOR THIS TIME OF YEAR...WITH PLENTY OF SUNSHINE ESPECIALLY ON TUESDAY. THURSDAY-SUNDAY: THUNDERSTORM CHANCES CONTINUE ON THURSDAY INTO FRIDAY AS THE UPPER TROUGH MOVES THROUGH THE CENTRAL PART OF THE COUNTRY. THURSDAY LOOKS TO BE THE WARMEST DAY BEFORE TEMPERATURES RETURN TO NORMAL FOR THE WEEKEND. AT LEAST THAT`S THE WAY IT LOOKS RIGHT NOW. SCHRECK AVIATION...06Z TAFS [RSL/SLN/HUT/ICT/CNU] MAIN CONCERN WILL BE POTENTIAL FOR MVFR CIGS. COLD FRONT WAS ENTERING NORTHWESTERN NEBRASKA LATE THIS EVENING AND WILL APPROACH CENTRAL KS EARLY MON AM. THE FRONT WILL SLOW DOWN CONSIDERABLY OVER S-CNTRL/SERN KS MON/MON EVE. LEADING EDGE OF GULF MOISTURE WAS INTO WESTERN OKLAHOMA LATE THIS EVE...AND PROGGED TO REACH CENTRAL/SOUTH CENTRAL KS OVERNIGHT INTO MON AM. THIS SURGE OF GULF MOISTURE WILL LIKELY BE ACCOMPANIED BY MVFR CIGS WHICH COULD LAST INTO MON PM AS LOW-LEVEL MOISTURE REMAINS TRAPPED BENEATH INVERSION. DEPENDING ON HOW MUCH IF ANY SUN/HEATING WE GET MON PM...THERE IS A CHANCE FOR AN ISOLD TS OR TWO ACROSS S-CNTRL/SERN KS. GIVEN INITIATION AND COVERAGE CONCERNS...WILL LEAVE OUT ANY MENTION OF TS AT THIS JUNCTURE. JMC && .PRELIMINARY POINT TEMPS/POPS... WICHITA-KICT 76 53 74 54 / 10 20 10 0 HUTCHINSON 71 47 71 51 / 10 10 10 0 NEWTON 74 51 71 52 / 10 20 10 0 ELDORADO 77 55 74 52 / 10 30 10 0 WINFIELD-KWLD 80 57 74 55 / 10 30 10 10 RUSSELL 71 40 71 46 / 10 10 10 0 GREAT BEND 72 41 71 48 / 10 10 10 0 SALINA 66 43 72 49 / 10 10 10 0 MCPHERSON 69 47 71 49 / 10 20 10 0 COFFEYVILLE 81 60 76 57 / 20 40 30 10 CHANUTE 80 59 75 53 / 20 40 30 10 IOLA 79 58 75 52 / 20 40 30 0 PARSONS-KPPF 80 60 76 56 / 20 40 30 10 && .ICT WATCHES/WARNINGS/ADVISORIES... NONE. && $$ ks AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 426 PM EDT MON APR 21 2008 .SYNOPSIS... 19Z WATER VAPOR LOOP AND RUC 500MB HEIGHT ANALYSIS SHOWED AN UPPER TROUGH OVER THE PACIFIC NW INTO SW CANADA CONSISTING OF TWO UPPER LOWS...AND RIDGING OVER THE GREAT LAKES INTO SE CANADA. AHEAD OF THE UPPER TROUGH...THERE IS A SHRTWV MOVING THROUGH THE EASTERN DAKOTAS THAT IS HELPING TO GENERATE SHOWERS AND SOME THUNDERSTORMS OVER WRN MN INTO FAR NW ONTARIO...ALL BEHIND A COLD FRONT WHICH EXTENDS FROM CENTRAL MN DOWN INTO NW MISSOURI. FOR THIS FORECAST...HOWEVER... THERE ARE TWO MAIN UPPER JETS TO NOTE OF...ONE 90-100 KT STREAK FROM SE WYOMING INTO WRN SOUTH DAKOTA AND A MORE IMPRESSIVE 110 KT STREAK PUNCHING THROUGH SRN OREGON INTO NRN NEVADA. CWA REMAINS DRY WITH JUST SOME DIURNAL CUMULUS AROUND...THANKS TO SUBSIDENCE UNDER THE UPPER RIDGING. TEMPERATURES HAVE RISEN NICELY WITH A LOT OF SUN AND 850MB TEMPS BETWEEN 8-10C...AND HIGHS RIGHT NOW ARE IN THE 60S TO LOW 70S AWAY FROM LOCAL COOLING NEAR THE GREAT LAKES. ALSO TO NOTE IS A FOG/STRATUS DECK OVER CENTRAL LAKE MICHIGAN MOVING NORTHWARD ON SSE WINDS. THIS DECK IS BEING SUPPORTED BY MID TO UPPER 40S F DEWPOINTS CROSSING THE COLDER WATER OF LAKE MICHIGAN. TO OUR SW...A STREAM OF MOISTURE IS HEADING NORTHWARD ALONG THE COLD FRONT...NOTED BY PROFILER 850MB WINDS OF 20 TO 25 KT...SURFACE DEWPOINTS IN THE MID TO UPPER 50S...AND MODEL PROGGED PRECIPITABLE WATER AROUND 1 INCH. && .SHORT TERM (TONIGHT AND TUE)... UPPER TROUGH OVER THE PACIFIC NW AND SW CANADA IS PROGGED TO LIFT UP INTO CENTRAL CANADA BY 00Z WED. AHEAD OF THIS TROUGH...ONE SHRTWV CURRENTLY IN NORTHERN UTAH IS INDICATED TO LIFT UP INTO NW WI BY 18Z TUE...HELPING TO PUSH THE CURRENT RIDGE OVER THE AREA EASTWARD. MUCH OF THE CWA WILL BE UNDER THE INFLUENCE OF THE UPPER RIDGE THIS EVENING...THEREFORE DRY CONDITIONS CONTINUE. HOWEVER...AFTER 06Z...IT APPEARS SOME PCPN SHOULD EITHER START MOVING OR DEVELOPING INTO THE FAR WESTERN U.P. DUE TO A COUPLE OF FACTORS. FIRST...THE UPPER JET MAX IN WRN SOUTH DAKOTA IS PROGGED TO LIFT INTO NRN MN AND NW ONTARIO WHILE STRENGTHENING...BRINGING SOME UPPER DIVERGENCE IN FROM THE RIGHT ENTRANCE REGION. SECOND...MID-LEVEL FRONTOGENESIS THAT IS CURRENTLY PRESENT BEHIND THE COLD FRONT IN MN...AIDING IN THE PCPN THERE...IS INDICATED TO START MOVING ALONG THE FRONT. THIS FRONTOGENESIS WILL ACT ON THE INCREASING MOISTURE ALONG THE FRONT TO HELP PRODUCE PCPN. THIRD...500MB PRESSURE FIELDS DO SUGGEST SOME MINOR HEIGHT FALLS MOVING IN. ON TUESDAY...PCPN WILL MAKE ITS WAY EASTWARD ACROSS UPPER MI. THE SAME FACTORS WILL BE PRESENT...THOUGH THE UPPER LEVEL DIVERGENCE FORCING WILL NOW COME FROM THE UPPER JET MOVING INTO NRN NEVADA...PROGGED TO REACH CENTRAL WI BY 21Z TUE. HAVE MAINTAINED 70 POPS...THOUGH DEBATED GOING HIGHER. ALSO MAINTAINED THUNDERSTORM MENTION WITH 850-500MB LAPSE RATES OF 6.5-7 C/KM FEEDING INTO THE FRONTOGENESIS AXIS. AS FAR AS AMOUNTS OF PCPN GO...IT APPEARS A GENERAL 0.30 TO 0.50 INCH IS POSSIBLE. A FEW MODELS SUCH AS THE GFS INDICATE POTENTIALLY MORE...WHICH WOULD NOT BE OUT OF THE QUESTION GIVEN PRECIPITABLE WATER VALUES OF 250 PERCENT OF NORMAL MOVING INTO THE CWA. HOPEFULLY ANY HIGHER AMOUNTS WILL REMAIN ISOLATED GIVEN THE CURRENT ONGOING HYDROLOGY ISSUES. NEXT CONCERN IS FOG DECK ON LAKE MICHIGAN. 975-950MB WINDS STAY MOSTLY SSE THROUGH ABOUT 09Z...WHICH SHOULD BRING THE STRATUS AND FOG NORTHWARD INTO THE COUNTIES BORDERING LAKE MICHIGAN AT SOME POINT THIS EVENING. SOME LIGHT FOG IS ALREADY BEING REPORTED AT MNM AND ESC. THIS FOG AND STRATUS SHOULD MOVE NORTHWARD THROUGH MUCH OF THE EASTERN U.P. OVERNIGHT AWAY FROM DOWNSLOPING SOUTHERLY FLOW AREAS. 975-900MB WINDS SHIFT MORE SW AND EVENTUALLY WEST LATE TOMORROW...WHICH WILL MOVE THE FOG AND STRATUS EASTWARD. WILL NEED TO WATCH FOR ANY DENSE FOG WITH THIS DECK. LOW TEMPERATURES TONIGHT WILL BE MILD THANKS TO HIGH DEWPOINTS... INCREASING CLOUD COVER AND SOME BREEZE. WARMEST TEMPS WILL BE IN THE DOWNSLOPING FLOW AREAS. HIGHS TOMORROW ARE TRICKY WITH THE FOG/STRATUS DECK OVER THE EASTERN U.P.. WENT BELOW GUIDANCE THERE. GUIDANCE TEMPS SEEMED REASONABLE FOR THE REST OF THE CWA. HOURLY TEMPS ARE ALSO TRICKY WITH THE FRONT AND PCPN MOVING THROUGH...AND TRIED TO ACCOUNT FOR THIS IN THE FORECAST. .LONG TERM (TUE NIGHT THROUGH NEXT MON)... AS FLOW ALF BCMS MORE NORMAL TO THE SFC FNT TUE EVNG...EXPECT COLD FNT TO ACCELERATE E. WL MAINTAIN GOING POPS TUE EVNG OVER THE ERN ZNS BUT THEN END ALL PCPN AFT MIDNGT AS HI PRES RDG/VERY DRY AIRMASS (PWAT 0.25 TO 0.33 INCH) INVADES THE WRN LKS IN THE WAKE OF SHRTWV LIFTING NEWD THRU ONTARIO. WITH APRCH OF SFC HI CENTER DURING THE NGT AND DIMINISHING WINDS...TENDED TOWARD THE LO END OF MOS GUIDANCE OVER THE INTERIOR W HALF FOR MIN TEMPS. STEADIER NW FLOW OVER THE E WL LIMIT DIURNAL FALL OF TEMP. WED LOOKS TO BE A DELIGHTFUL SPRING DAY WITH HI PRES/DRY AIRMASS OVHD UNDER BLDG RDG DOWNSTREAM OF TROFFING IN THE ROCKIES. DEEP MIXING TO H75-7 OR SO OF GFS/NAM FCST SDNGS YIELDS HI TEMPS ARND 70 OVER THE INTERIOR W HALF AWAY FM LK MODERATION. OTRW...LGT WINDS WL ALLOW LK BREEZES TO DVLP...WITH COOLER TEMPS NR THE SHORES. WITH DEEP MIXING...EXPECT DWPTS TO MIX OUT INTO THE TEENS/20S IN THE AFTN...WITH RH OVER THE INTERIOR DROPPING AOB 20 PCT. DRY AIR WL AID THE DIURNAL FALL OF TEMP ON WED NGT DESPITE SOME INCRSG HI CLDS. BUT INCRSG SSE DOWNSLOPE FLOW WL MITIGATE DIURNAL FALL OF TEMP OVER THE FAR W FM IWD TO ONT. IN THE MID TERM...UPR RDGING/MID LVL DRY AIR WL REMAIN IN PLACE ON THU...AND 06Z-12Z GFS/00Z ECMWF KEEP NEXT COLD FNT/BULK OF DEEPER MSTR IN WARM CONVEYOR BELT E OF TROFFING IN THE NRN ROCKIES W OF IWD THRU 00Z FRI. SO WL RESTRICT CHC POPS TO THE FAR WRN ZNS/WRN LK SUP IN THE AFTN WITH HI AMPLITUDE PATTERN FAVORING THE SLOWER EWD PROGRESSION AND MAINTENANCE OF MID LVL DRY AIR/CAPPING. LOOKS LIKE SOME SUNSHINE FILTERED BY HI CLD TO THE E. WITH SLY FLOW BTWN DEPARTING HI AND INCOMING COLD FNT AS WELL FCST H85 TEMPS IN THE 10C-12C RANGE... EXPECT HI TEMPS TO APRCH 70 AWAY FROM THE MODERATING INFLUENCE OF LK MI...WHERE GFS FCST SDNGS HINT THAT SOME ST/SC MAY ROLL IN OFF LK MI. ON THU NGT/FRI/FRI NGT...PROGRESSED CHC POPS W-E ACRS THE FA ON THU NGT. THE 00Z ECMWF...FVRD BY NCEP...IS A BIT SLOWER WITH THE EWD PROGRESSION OF THE FNT AS ITS UPR FLOW IS MORE MERIDIONAL THAN SHOWN BY THE GFS. THE 00Z CNDN MODEL HAS ALSO TRENDED TOWARD A HIER AMPLITUDE PATTERN AS WELL. SO SLOWED DOWN DEPARTURE OF HIER POPS ON FRI/FRI NGT. ALTHOUGH THE EXPLICIT ECMWF DOES NOT SHOW HVY PCPN... THE NEARLY PARALLEL ORIENTATION OF THE H5 FLOW WITH THE SFC FNT FCST AT 00Z SAT OVER THE ERN CWA RAISES THE SPECTER OF HVY RA WITH H85 DWPTS UP TO 10C. SUCH A SCENARIO WOULD EXACERBATE HI RIVER LVLS. INTRODUCED A CHC OF SHSN AS WELL OVER THE W HALF LATE AT NGT WITH ECMWF SHOWING H85 TEMPS FALLING TOWARD -10C. WITH A DEEPENING UPR TROF ACRS THE UPR LKS OVER THE WEEKEND...EXPECT TEMPS TO FALL BLO NORMAL AND TOWARD THE LO END OF GFS MOS GUIDANCE. THE DEEPER 00Z CNDN MODEL SHOWS A NEARLY H5 LO CUTOFF OVER THE GRT LKS ON SAT. VARIOUS RECENT MODELS HAVE FCST THIS OCCURRENCE...BUT WL TREND TOWARD THE DRIER 00Z ECMWF RIGHT NOW PER NCEP GUIDANCE. LO CHC POPS FOR MIXED RA/SN SEEM APPROPRIATE AS IN GOING FCST WITH THERMAL TROF OVHD. DAYTIME HTG/DESTABILIZATION WL ACCENTUATE THE PCPN CHCS IN THE MOIST...CHILLY NNW FLOW. AFT A BRIEF TIME OF QUIET WX SAT NGT WITH RDG AXIS IN CONTROL/LOSS OF DIURNAL HTG AND CHILLY MIN TEMPS AT THE LO END OF MOS GUIDANCE...FOCUS TURNS TO NEXT CLIPPER SHRTWV/SFC LO FCST BY NCEP FVRD 00Z ECMWF MODEL. HAVE SPREAD POPS FOR SHRA W-E ACRS THE FA ON SUN WITH THE APRCH OF THIS SYS. FCST THE RA TO MIX WITH SN WITH CYC NNE FLOW AND H85 TEMPS FCST TO FALL AS LO AS -6C BEFORE THE PCPN MOVES TO THE E ON MON AND ENDS THE PCPN. COORDINATED WITH GRB/DLH. && .HYDROLOGY...RIVERS ACROSS THE U.P. CONTINUE TO RISE IN RESPONSE TO RUNOFF FROM SNOWMELT AND GIVEN THE WARM TEMPERATURES TODAY A SIGNIFICANT AMOUNT OF THE REMAINING SNOW COVER SHOULD GO. ONE EXCEPTION MAY BE AT THE CHOCOLAY RIVER WHERE THE MOST RECENT FORECAST SHOWS A RECEDING TREND IN THE RIVER STAGE. LATEST OBSERVATIONS SHOW THE CURRENT STAGE IS AROUND 9 FEET. THERE IS SOME UNCERTAINTY HOW MUCH SNOW IS LEFT TO MELT WITHIN THAT BASIN. A LITTLE CONCERNED THE RIVER MAY RISE A BIT TODAY WITH WHATEVER SNOWMELT CONTRIBUTION THERE IS...SO OPTED TO LEAVE FLOOD ADVISORY UP TILL ITS CLEAR THE RIVER IS RECEDING. OVERNIGHT THE TRAP ROCK RIVER WENT ABOVE FLOOD STAGE. EVEN THOUGH ITS CURRENTLY BELOW FLOOD STAGE...8.5 FEET...OPTED TO CONTINUE THE FLOOD WARNING AS SIGNIFICANT SNOWMELT IN THAT BASIN WILL ALLOW THE RIVER TO RISE TO FLOOD STAGE AGAIN SOMETIME TONIGHT. CHASSELL STAFF GAUGE STILL READING AROUND 10.6...SEE NO REASON THIS WILL CHANGE ANYTIME SOON. LOOKING AHEAD TO THE NEXT COUPLE DAYS...THE MICHIGAMME RIVER NEAR WITCH LAKE AND REPUBLIC...THE STURGEON RIVER NEAR ALSTON...AND THE MIDDLE BRANCH OF THE ESCANABA RIVER NEAR HUMBOLDT ARE THE RIVERS TO WATCH. THINK THE MICHIGAMME AND STURGEON NEAR ALSTON HAVE THE BEST OPPORTUNITY OF THE THREE TO GO ABOVE FLOOD STAGE. AT HUMBOLDT LATEST RFC GUIDANCE INDICATES A CREST BELOW FLOOD STAGE ON THE MORNING OF THE 23RD. FOR CONTINUED UPDATES ON THE RIVERS... PLEASE SEE THE LATEST HYDROLOGIC STATEMENTS AND ANY FLOOD WATCHES OR WARNINGS THAT MAY BE ISSUED. IN ADDITION...FOR THE LATEST FORECAST PLEASE VISIT THE AHPS PAGE AND CLICK ON A RIVER SITE...THIS CAN BE FOUND UNDER THE RIVERS AND LAKES LINK AT WWW.WEATHER.GOV/UP && .AVIATION (FOR THE 18Z TAF ISSUANCE)... OVERALL DRY AIR ACROSS UPPER MICHIGAN WILL MAINTAIN VFR CONDITIONS THROUGH THIS EVENING AT BOTH TAF SITES. AFTER MIDNIGHT...CONCERN EXISTS FOR SAW DEVELOPING BOTH FOG AND STRATUS. THIS IS DUE TO SSE FLOW JUST OFF THE SURFACE BRINGING UP THE CURRENT FOG/STRATUS DECK OVER CENTRAL LAKE MICHIGAN. HOWEVER...THERE IS SOME UNCERTAINTY ON HOW SE THE LOW LEVEL FLOW ACTUALLY IS...WITH SOME MODELS SUGGESTING MORE SOUTH TO SW. THEREFORE HAVE NOT WENT TOO PESSIMISTIC YET. FUTURE SHIFTS WILL NEED TO KEEP AN EYE ON THE LOW LEVEL WIND FLOW. IF THE DECK DOES MOVE IN...WOULD NOT BE SURPRISED TO SEE LIFR CIG AND VIS. KEPT IN SOME LLWS AT SAW AS WELL AS A LOW LEVEL JET PASSES ACROSS (THOUGH THE LLWS IS MARGINAL AT BEST). CMX WILL REMAIN VFR THROUGH THE NIGHT AS THE WIND DIRECTION DOWNSLOPES OFF THE HURON MOUNTAINS. ON TUE...BAND OF SHOWERS AND EMBEDDED THUNDERSTORMS CURRENTLY IN FAR WESTERN MN IS EXPECTED TO MOVE INTO CMX IN THE MORNING...BRINGING VIS AND CIGS DOWN TO MVFR. THEY MIGHT EVEN DROP TO IFR...BUT THINK THE BETTER CHANCE OF THAT HAPPENING IS AT 18Z. PCPN SHOULD HOLD OFF UNTIL JUST AFTER 18Z AT SAW. && .MARINE (FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE)... THROUGH WEDNESDAY NIGHT...WINDS OF 25 KNOTS OR LESS ARE EXPECTED. WINDS WILL INCREASE ON THU ACROSS LAKE SUPERIOR AS A COLD FRONT APPROACHES FROM THE PLAINS...AND ESPECIALLY THU NIGHT WHEN LOW PRESSURE ALONG THE FRONT DEEPENS AS IT LIFTS INTO NW ONTARIO. SE GALE FORCE WINDS TO 35 KNOTS ARE POSSIBLE...PRIMARILY THURSDAY EVENING. AFTER THE FRONT CROSSES LAKE SUPERIOR ON FRIDAY...ANOTHER LOW MOVING UP ALONG THE FRONT IS EXPECTED TO LIFT INTO NE ONTARIO BY SATURDAY MORNING. NW WINDS UP TO 30 KT ARE EXPECTED BEHIND THIS LOW BEFORE WINDS RELAX SOME LATE SATURDAY. && .MQT WATCHES/WARNINGS/ADVISORIES... FLOOD WARNING FOR THE STURGEON RIVER NEAR ALSTON AND CHASSELL FLOOD WARNING FOR THE TRAP ROCK RIVER NEAR LAKE LINDEN FLOOD ADVISORY FOR THE CHOCOLAY RIVER NEAR HARVEY && $$ SYNOPSIS/SHORT TERM...AJ LONG TERM...KC HYDROLOGY...DJP AVIATION...AJ MARINE...AJ/KC mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN 339 PM CDT MON APR 21 2008 .DISCUSSION... MAIN FORECAST CONCERNS TODAY REVOLVE AROUND PCPN CHANCES TONIGHT INTO WEDNESDAY MORNING...THEN ADDITIONAL THREAT OF PCPN WEDNESDAY NIGHT THROUGH THURSDAY. THE LATEST WATER VAPOR IMAGERY AND RUC ANALYSES SHOW A FAIRLY CONVOLUTED UPPER AIR PATTERN ACROSS THE CONUS AT THIS TIME. A CUTOFF LOW COULD BE SEEN SPINNING ALONG THE CAROLINA COAST...WITH A SHARP RIDGE SEPARATING THIS FROM THE BROAD UPPER LOW OVER THE NORTHWEST CONUS AND SOUTHWEST CANADA. A SHORTWAVE TROUGH WAS ROTATING AROUND THE UPPER LOW...THROUGH NORTH DAKOTA AND INTO MANITOBA...HELPING TO SUPPORT THE SHRA AND TSRA TO OUR WEST. SURFACE ANALYSIS PLACES THE COLD FRONT FROM NORTH CENTRAL MINNESOTA INTO NORTHWEST IOWA AT THIS TIME...WITH SHRA/TSRA GENERALLY POST FRONTAL IN NATURE GIVEN LIMITED BOUNDARY LAYER INSTABILITY AHEAD OF IT. HOWEVER...ELEVATED INSTABILITY IS AVAILABLE...PER ELEVATED CAPE VALUES OF 500-1000 J/KG...AND WITH FRONT RELATIVE FLOW PROVIDING UPGLIDE OVER THE COLD FRONTAL SURFACE WE SHOULD CONTINUE TO SEE DEVELOPMENT OF SHRA/TSRA THROUGH THE NIGHT AS THE BOUNDARY TRUDGES EASTWARD. GENERALLY FOLLOWED A BLEND OF THE NAM AND GFS GUIDANCE IN THE HANDLING OF TODAY/S SYSTEM...THEN WENT CLOSER TO A GFS/SREF BLEND FOR THE NEXT SYSTEM WHICH IS EXPECTED TO IMPACT THE REGION WEDNESDAY NIGHT THROUGH THURSDAY. AS MENTIONED...WE SHOULD CONTINUE TO SEE SOME POST-FRONTAL SHRA/TSRA DEVELOPMENT THROUGH THE NIGHT AS FRONT RELATIVE FLOW WILL CONTINUE TO RESULT IN SOME ISENTROPIC UPGLIDE IN THE ZONE WHERE SATURATION WILL CORRESPOND WITH ELEVATED INSTABILITY. FRONTOGENESIS IN THE 700-600MB LAYER WILL PERSIST AS WELL...AND ALTHOUGH IT LOOKS LIKE IT WANES A BIT THIS EVENING...BOTH THE NAM AND GFS SUGGEST IT WILL REINVIGORATE SOME LATER THIS EVENING OVER EASTERN MINNESOTA AND WESTERN WISCONSIN. WITH THE FRONT FAIRLY PARALLEL TO THE MID-LEVEL FLOW...FIGURE IT WILL CONTINUE TO MOVE QUITE SLOWLY...SO KEPT SOME CHANCE OF SHRA AROUND INTO THE MORNING HOURS...WITH A MENTION OF THUNDER FARTHER EAST. SUFFICIENT RIDGING AND SUBSIDENCE SHOULD WORK INTO THE AREA DURING THE AFTERNOON TO BRING THINGS TO AN END ACROSS THE ENTIRE AREA...WITH DRY WEATHER EXPECTED TO PERSIST THROUGH WEDNESDAY. THE NEXT FEATURE OF INTEREST CAN CURRENTLY BE SEEN ROTATING AROUND THE WEST SIDE OF THE NORTHWEST CONUS UPPER LOW...JUST OFF THE PACIFIC NORTHWEST COAST. THIS SHORTWAVE WILL SWING EASTWARD OVER THE NEXT 24 TO 36 HOURS...AND THE MEAN TROUGH IS ANTICIPATED TO PUSH EAST WITH IT AS RIDGING ATTEMPTS TO BUILD OFF THE WEST COAST. RETURN FLOW SHOULD SPREAD MID-HIGH CLOUDS INTO THE AREA WEDNESDAY AFTERNOON...WITH GOOD ISENTROPIC LIFT AND BETTER MOISTURE ARRIVING WEDNESDAY NIGHT. A VIGOROUS LOW LEVEL JET IS EXPECTED TO DEVELOP INTO THE AREA WEDNESDAY NIGHT...COINCIDENT WITH ARRIVAL OF THE 850 MB THETA-E RIDGE. ELEVATED INSTABILITY WILL AND FORCING ALONG THE 925-850MB FRONT SHOULD HELP SHRA/TSRA TO DEVELOP FROM WEST TO EAST WEDNESDAY NIGHT INTO THURSDAY MORNING...AND MOISTURE SHOULD CONTINUE TO SURGE NORTH THROUGH THE DAY ON WEDNESDAY...AHEAD OF THE SURFACE FRONT WHICH CURRENTLY LOOKS LIKE IT WILL SLIDE THROUGH THURSDAY EVENING. AT THIS POINT...IT IS TOUGH TO PIN DOWN WHERE THE MOST SIGNIFICANT RAIN WILL OCCUR...ALTHOUGH MOST OF THE GUIDANCE SUGGESTS IT MAY BE JUST TO OUR NORTH AS WE GET INTO THE WARM SECTOR ON THURSDAY. HOWEVER...IF THIS OCCURS THEN WE MAY HAVE TO DEAL WITH THE POSSIBILITY OF SEVERE WEATHER WITH MLCAPE VALUES PROGGED TO CLIMB ABOVE 1000 J/KG AS SHEAR INCREASES AHEAD OF THE SHORTWAVE AND SURFACE FRONT THURSDAY AFTERNOON. THINGS SHOULD BECOME BETTER DEFINED OVER THE NEXT FEW DAYS...BUT THERE IS ENOUGH AGREEMENT AT THIS POINT TO EXPECT SOME DEGREE OF UNSETTLED WEATHER FROM LATE WEDNESDAY NIGHT INTO THURSDAY NIGHT. WILL CARRY HIGH CHANCE AND LIKELY POPS FROM WEST TO EAST THROUGH THE PERIOD. DURING THE FRIDAY THROUGH MONDAY TIME FRAME THE MEDIUM RANGE GUIDANCE IS NOT IN THE GREATEST OF AGREEMENT...PARTICULARLY WITH REGARD TO THE TIMING AND AMPLITUDE OF SHORTWAVES AND ASSOCIATED FRONTAL BOUNDARIES MOVING THROUGH THE REGION. THE 06Z GFS IS MARKEDLY DIFFERENT FROM ITS 00Z COUNTERPART...LIKELY UNDERSCORING THE UNCERTAINTY IN HOW THINGS WILL LIKELY EVOLVE DURING THE LATTER HALF OF THE WEEK THROUGH THE WEEKEND. THE ECMWF...GFS...AND CANADIAN MODELS ARE SOMEWHAT SIMILAR WITH RESPECT TO LONG WAVE FEATURES...SO WILL TRY TO LEVERAGE THAT INFORMATION...AND TREND MORE TOWARD A BLEND OF THE 00Z GFS ENSEMBLES AND ECMWF FOR THE DETAILS...WHICH MATCH UP REASONABLY WELL WITH THE HPC MANUAL PROGS FOR THE PERIOD. THE UPPER AIR PATTERN IS EXPECTED TO BE FAIRLY CONVOLUTED AND COMPLEX...AS CAN OFTEN BE EXPECTED DURING SPRING...AND GIVEN THE PROPENSITY FOR CUTOFF UPPER LOWS FROM THE EASTPAC ACROSS TO THE NORTH ATLANTIC...BOTH IN THE GUIDANCE AND IN REALITY...THE SOMEWHAT LESS PROGRESSIVE SOLUTION OF THE ECMWF SEEMS REASONABLE. SHORTWAVE TROUGH AND ASSOCIATED FRONTAL BOUNDARY IS EXPECTED TO SLIDE THROUGH THE AREA ON FRIDAY...WITH CHANCES FOR SHRA AND PERHAPS SOME THUNDER WITH SHOWALTER INDICES NEAR ZERO. THIS MATCHES THE GOING FORECAST FAIRLY WELL...SO DO NOT ANTICIPATE MAJOR CHANGES. THE ECMWF MAY BE A BIT TOO COOL WITH ITS POST FRONTAL TEMPERATURES...BUT MAY SHADE TEMPERATURES A SLIGHT BIT IN THAT DIRECTION TO ACCOUNT FOR THINGS. HEIGHTS WILL REMAIN FAIRLY LOW OVER THE REGION ON SATURDAY...BUT IT LOOKS LIKE LOW LEVEL RIDGING SHOULD BE SUFFICIENT TO SQUASH ANY CHANCES FOR PCPN AS THE SHORTWAVE TROUGH CONTINUES TO MOVE EAST. ANOTHER SHORTWAVE IS PROGGED TO ROTATE AROUND THE NORTHERN CANADA UPPER LOW ON SUNDAY...HELPING TO PUSH A WEAK SURFACE LOW AND FRONTAL BOUNDARY THROUGH THE AREA. WILL INCLUDE A CHANCE OF SHRA TO COVER THINGS...AS IT APPEARS THE ELEVATED INSTABILITY WILL REMAIN SUFFICIENTLY FAR TO THE SOUTH TO LEAVE A MENTION OF THUNDER OUT OF THE FORECAST. IN FACT...NORTH OF THE SURFACE LOW THE ECMWF WOULD ACTUALLY BE MARGINALLY COOL ENOUGH FOR SNOW OVER THE NORTHERN CWFA SUNDAY...BUT WILL ALSO LEAVE THAT POSSIBILITY OUT AT THIS POINT. MORE SUBSTANTIAL RIDGING...SURFACE AND ALOFT...IS EXPECTED TO ARRIVE BEHIND THIS SYSTEM AS THE MAIN LONGWAVE TROUGH OVER CENTRAL CANADA SLIDES A BIT TO THE EAST. WILL END CHANCES FOR PCPN SUNDAY EVENING AND GO WITH A DRY FORECAST FOR MONDAY. && .AVIATION... /18Z TAF ISSUANCE/ COLD FRONT NEAR AN KAXN TO KRWF LINE ATTM. FRONT IS PROGRESSING SLOWLY EAST AND EXPECTED TO PASS KSTC BY 21Z AND KMSP BY 01Z. FRONTAL TIMING FOR KRNH AND KEAU A LITTLE QUESTIONABLE AS A WAVE RIDES NORTHEAST ALONG THE FRONT. USED 03Z FOR PASSAGE AT KRNH AND 08Z FOR KEAU. ELEVATED INSTABILITY TO INCREASE BEHIND THE FRONT THIS AFTERNOON AND EVENING WITH RAIN SHOWERS AND SCATTERED THUNDERSTORMS INCREASING. CEILINGS FORECAST TO DROP BELOW 1000 FEET IN THE WAKE OF THE FRONT DUE TO SATURATION AND PRECIPITATION. EXTENSIVE LOW CEILINGS AND VISIBILITIES LATER TONIGHT FOR THE WI TAF SITES IN THE WAKE OF THE FRONT. THIS WILL PERSIST THROUGH MUCH OF TUESDAY MORNING BEFORE IMPROVEMENT SETS IN. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...NONE. WI...NONE. && $$ TRH/RAH mn AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE KANSAS CITY/PLEASANT HILL MO 455 PM CDT MON APR 21 2008 .UPDATE... 21Z SFC ANALYSIS INDICATES SFC FRONT HAS MOVED TO A MARYVILLE TO TOPEKA LINE...WITH SOME INCREASED FORWARD ACCELERATION NOTED...AS FORECAST BY THE 18Z NAM-WRF. MESOANALYSIS ALSO INDICATES MODEST SFC CONVERGENCE ALONG THE FRONTAL BOUNDARY...WITH THE GREATEST MAGNITUDE NEAR THE FRONTAL SEGMENT NEAR EMPORIA...WITH LOWER 60 DEWPOINTS INTERSECTING THE BOUNDARY. HOWEVER...700 MB ANALYSIS STILL SHOWS STOUT CAPPING INVERSION WITH +8C BUBBLE COVERING MUCH OF THE WARM SECTOR ALONG THE KANSAS/MISSOURI BORDER...SIGNIFICANTLY LIMITING THE DEPTH OF CONVECTIVE ELEMENTS. PREFRONTAL MLCAPES ANALYZED BETWEEN 500 AND 1000 J/KG WITH A FAIR AMOUNT OF CIN REMAINING DUE TO THE WARM NOSE. VERY LITTLE CHANGE IN THINKING FROM THE PREVIOUS DISCUSSION REGARDING CONVECTIVE INITIATION AND STORM MODE. PRIMARILY FOCUSING ON TWO MAIN AREAS FOR THE NEXT COUPLE HOURS FOR STORM FORMATION 1) COINCIDING WITH THE STRONGEST LOW LEVEL CONVERGENCE OVER CNTRL KANSAS ALONG THE WRN EDGE OF THE WARM LAYER WHERE SOME WEAK MIDLEVEL CAA SHOULD LEAD TO MORE MARGINAL DESTABILIZATION ALONG AN BEHIND THE SFC FRONT AND IN CONJUNCTION WITH THE 850 MB FRONT...AND 2) OVER FAR NWRN MISSOURI AND ERN NEBRASKA/SWRN IOWA ON THE NRN PERIPHERY OF THE MIDLEVEL CAPPING IN AN AREA OF CONVERGENCE ALONG THE 850 MB FRONT WITH MUCAPES AROUND 500 J/KG. OVERALL DYNAMIC FORCING STILL LOOKS TO BE QUITE WEAK WITH ONLY NOTABLE MIDLEVEL WAVE ONLY NOW MAKING IT INTO SRN COLORADO. FEEL THE LATEST 18Z GFS MAY HAVE THE BEST HANDLE ON THE POST SFC FRONTAL CONVECTION ALONG THE 850 MB FRONT RATHER THAN THE NAM-WRF WHICH MAY BE A BIT TOO ROBUST WITH SFC DEWPOINTS. STILL CANNOT TOTALLY DISCOUNT PREFRONTAL CONVECTION AFTER DARK AS SUGGESTED BY RUC FORECAST...AND EVEN HINTED AT BY GFS BUFR SOUNDINGS CLOSER TO CNTRL MISSOURI. 21 && .DISCUSSION... /332 PM CDT MON APR 21 2008/ CU FIELD HAS DEVELOPED ACROSS EASTERN KANSAS INTO WESTERN MISSOURI THIS AFTERNOON IN THE WAKE OF MORNING STRATUS. BRIEF MESO LOW WAS EVIDENT VIA VIS SATELLITE IMAGERY WITH WEAK REFLECTION IN THE SFC OBSERVATIONS JUST EAST OF SALINA DURING THE EARLY AFTERNOON HOURS. THIS FEATURE HAS SINCE BECOME STRETCHED AND ELONGATED AS SFC FRONTAL BOUNDARY HAS CREPT INTO THE AREA. OTHERWISE...CU FIELD ENHANCING THIS AFTERNOON AS INSTABILITY AXIS SLOWLY EDGES NORTHWARD INTO EASTERN KANSAS. CURRENTLY BECOMING PESSIMISTIC IN REGARDS TO WHETHER SFC BASED CONVECTION WILL DEVELOP AS STOUT CAPPING REMAINS IN PLACE THIS AFTERNOON ALONG WITH A LACK OF SUBSTANTIAL UPPER LEVEL SUPPORT. NEVERTHELESS IF A STORM CAN BREAK THROUGH THE CAP AND DEVELOP WITHIN PREFERENTIAL ENVIRONMENT...MLCAPE VALUES ON THE ORDER OF 1000J/KG SHOULD BE EDGING INTO EASTERN KANSAS BY LATER THIS AFTERNOON AHEAD OF THE SOUTHEASTERLY ADVANCING COLD FRONT CURRENTLY MOVING INTO NORTHWEST MISSOURI. DEEP LAYER SHEAR REMAINS MARGINAL FOR SUPERCELLULAR DEVELOPMENT WITH 0-6KM BULK SHEAR VECTORS STRUGGLING TO REACH 30KTS ACROSS EASTERN KANSAS INTO WESTERN MISSOURI. THEREFORE...WOULD LIKELY SEE A MIX OF PULSE TO MULTICELL DEVELOPMENT WITH PERHAPS A SUPERCELL OR TWO IN THE MIX. MORE LIKELY DEVELOPMENT SEEMS TO BE ALONG AND NORTH OF SFC BOUNDARY THIS EVENING...MORE FOCUSED ALONG H85 BAROCLINIC ZONE WHERE INITIATION CAN FOCUS ABOVE THE INVERSION. THIS DEVELOPMENT HAS THE POTENTIAL TO BECOME STRONG TO SEVERE AS ADVANCING UPPER LEVEL IMPULSE WILL INCREASE OVERALL DEEP LAYER SHEAR BY LATER THIS EVENING HELPING TO SUSTAIN UPDRAFTS. IN ADDITION...MID LEVEL LAPSE RATES CURRENTLY ON THE ORDER OF 8.5 C/KM WOULD SUPPORT VIGOROUS UPDRAFTS WITH THE POTENTIAL TO PRODUCE LARGE HAIL. ALSO...LATEST MESOSCALE ANALYSIS SHOWING DCAPE AOA 1000 J/KG ACROSS THE AREA WHICH WOULD SUPPORT STRONG DOWNDRAFT POTENTIAL WITH MORE VIGOROUS ACTIVITY...WHICH SEEMS PLAUSIBLE GIVEN AMOUNT OF MID LEVEL DRY AIR ABLE TO EVAPORATIVELY COOL ANY PRECIP. SLOW MOVING FRONT MAY STILL LINGER ACROSS THE EASTERN COUNTIES BY TOMORROW MORNING WITH PRECIP CHANCES LIKELY FOCUSED ACROSS THIS AREA BY THEN. PRECIP SHOULD WIND DOWN DURING THE DAY TOMORROW WITH A BRIEF REPRIEVE BY THE AFTERNOON HOURS. FRONT DOESN`T LOOK TO MAKE IT VERY FAR SOUTH BEFORE STALLING BY TOMORROW NIGHT....MOST LIKELY ACROSS SOUTHERN MISSOURI AS PRESSURE FALLS PROMOTE EASTERLY LLVL FLOW TO TAKE SHAPE BY WEDNESDAY MORNING. WARM FRONT LIFTS BACK INTO THE AREA BY WEDNESDAY AHEAD OF THE NEXT UPPER LEVEL SHORT WAVE TROUGH TO AFFECT THE AREA. FINE TUNED POPS A BIT FOR WEDNESDAY FOCUSING MORE TOWARDS THE NIGHT TIME PERIODS...MORE ALIGNED WITH STRONGER UPPER LEVEL SUPPORT. NEVERTHELESS...AMPLE MOISTURE SHOULD BE IN PLACE FOR PRECIPITATION PRODUCTION. DEROCHE MEDIUM RANGE... MOISTURE CONTINUES TO OVERSPREAD THE REGION DURING THE DAY THURSDAY. ECMWF/GFS SEND A SHORTWAVE NORTHEAST ACROSS THE REGION DURING THE DAY THURSDAY...AHEAD OF A COLD FRONT. MODELS ALSO CONTINUE TO SHOW THE COLD FRONT MOVING SOUTH ACROSS THE AREA DURING THE DAY FRIDAY...ALBEIT SOMEWHAT SLOWER. DUE TO PRETTY GOOD RUN TO RUN CONSISTENCY IN THE LAST DAY OR SO...HAVE BUMPED UP POPS A LITTLE MORE FOR THE THURSDAY THROUGH FRIDAY TIMEFRAME. AIRMASS WILL BE FAIRLY JUICY SO LOCALLY HEAVY RAIN WILL BE POSSIBLE. WILL CONTINUE THE DRY FORECAST FOR LATE FRIDAY NIGHT INTO SATURDAY. HAVE GONE AHEAD AND INTRODUCED SLIGHT CHANCE POPS FOR SUNDAY...AS FAVORED MORE CONSISTENT ECMWF BRINGS THE NEXT COLD FRONT ACROSS AT THAT TIME. WITH FRONTS WOBBLING BACK AND FORTH ACROSS THE REGION THROUGHOUT THE THURSDAY THROUGH MONDAY TIMEFRAME...WILL STICK WITH NEAR NORMAL TEMPS. NRR && .AVIATION... FAIRLY WIDESPREAD CU FIELD NOW IN PLACE THIS AFTERNOON ACROSS THE TERMINALS AND THIS SHOULD HANG ON FOR THE NEXT SEVERAL HOURS. SOUTHEASTERLY ADVANCING COLD FRONT NOW MOVING INTO NORTHWEST MISSOURI WILL BE THE FOCUS FOR SHOWER AND THUNDERSTORMS DEVELOPMENT BY LATER THIS EVENING. SOME QUESTION AS HOW LONG PRECIP WILL LAST NEAR THE TERMINAL SITES AND WILL FINE TUNE AS NECESSARY. OTHERWISE...EXPECTING SOUTHERLY LLVL FLOW TO CONTINUE UNTIL FRONTAL BOUNDARY MOVES THROUGH LATER TONIGHT...SWITCHING WINDS AROUND TO A MORE NORTHERLY DIRECTION. DEROCHE && .EAX WATCHES/WARNINGS/ADVISORIES... MO...NONE. KS...NONE. $$ mo AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE SPRINGFIELD MO 225 PM CDT MON APR 21 2008 .DISCUSSION... FORECAST CHALLENGES DEAL WITH SEVERE WEATHER POTENTIAL TONIGHT THROUGH TUESDAY AND PRECIPITATION CHANCES THROUGHOUT THE WEEK. SHORT TERM (TODAY THROUGH WEDNESDAY NIGHT)... CURRENTLY...COLD FRONT EXTENDS FROM EXTREME EASTERN NEBRASKA THROUGH SOUTH CENTRAL KANSAS BACK INTO THE TEXAS PANHANDLE THIS AFTERNOON. DEWPOINTS OVER EASTERN OKLAHOMA...INTO EASTERN KANSAS INTO THE LOW TO MID 60S WITH UPPER 50S ACROSS WESTERN MISSOURI. 12Z SGF SOUNDING THIS MORNING SHOWED A VERY STRONG CAPPING INVERSION FROM AROUND 800MB TO 770MB...SO CONVECTION HAS YET TO BEGIN. SEVERE WEATHER WILL BE HIGHLY CONDITIONAL ON THIS CAPPING INVERSION BREAKING THIS EVENING. COLD FRONT FORECAST TO APPROACH EXTREME SOUTHEAST KANSAS LATE THIS EVENING. LATEST RUC SOUNDINGS FOR EXTREME SOUTHEAST KANSAS KEEPS CAPPING INVERSION IN PLACE THROUGH AT LEAST THROUGH 03Z. DO BELIEVE AS THE FRONT MOVES IN...WE SHOULD SEE THIS CAP WEAKENING OUT WEST. THAT AND THE GFS SHOWS A 25-30KT 925MB JET SETTING UP THAT SHOULD PROVIDE SOME FOCUS FOR LIFT. BY 06Z...CAP ON THE RUC SOUNDING DEFINITELY WASHED OUT AND CONVECTION SHOULD REALLY GET GOING. SB CAPES OUT WEST AT AROUND 2200 J/KG AND SOUNDING SHOWING A VERY FAVORABLE SOUNDING FOR LARGE HAIL. 0-3KM HELICITIES RIGHT AROUND 200M2/S2...SO WENT AHEAD AND KEPT CHANCE OF ISOLATED TORNADOES IN THIS AFTERNOONS HWO. CAP IS A LITTLE STRONGER EAST NEAR SPRINGFIELD AND THREAT FOR THIS AREA SHOULD BE MORE IN LINE OF LARGE HAIL AND DAMAGING WINDS. EVENING SHIFT WILL NEED TO CLOSELY MONITOR EVENTS THROUGH THE EVENING AND HAZARDS MAY NEED TO BE EXTENDED FURTHER EAST. COLD FRONT SLOWLY MOVES EAST TUESDAY MORNING. BY 18Z...SURFACE LOW FORECAST ON GFS PROGGED TO BE OVER NORTHEAST MISSOURI...WITH TRAILING COLD FRONT RIGHT ALONG OSAGE BEACH TO SPRINGFIELD TO JOPLIN LINE AT THAT TIME. OUT AHEAD OF THE FRONT...GFS FORECAST CAPES OVER SOUTHEAST AND EAST CENTRAL MISSOURI RIGHT AROUND 1500 J/KG...SO COMMUNITIES GENERALLY SOUTH OF THE INTERSTATE 44 CORRIDOR WILL BE IN THE BULLSEYE FOR SEVERE WEATHER DURING THE AFTERNOON. AGAIN...SHEAR NOT ALL THAT GREAT FOR A TORNADIC THREAT...AND LARGE HAIL AND DAMAGING WINDS ARE EXPECTED TO BE THE MAIN THREATS. FRONT CLEARS THE CWA TO THE EAST AND SOUTH TUESDAY EVENING...WITH FRONT HANGING UP OVER NORTHERN ARKANSAS EARLY WEDNESDAY MORNING. THIS FRONT WILL BE THE FOCUS FOR ADDITIONAL RAINFALL LATER IN THE WEEK. WITH EASTERLY FLOW WEDNESDAY...DO BELIEVE CWA SHOULD BE MOSTLY DRY. CLAYCOMB LONG TERM (THURSDAY THROUGH MONDAY)... A HIGH AMPLITUDE BUT FAIRLY PROGRESSIVE UPPER FLOW PATTERN IS EXPECTED FOR MUCH OF THIS TIME. QUITE A FEW DISCREPANCIES BETWEEN THE 12Z GFS AND 00Z ECMWF DURING THIS TIME FRAME. GENERALLY FOLLOWED THE ECMWF AND HPC GUIDANCE. MAIN COMMON FEATURES EARLY ARE A TROUGH OVER WESTERN NOAM...BUT MAIN DIFFERENCES CONCERN HOW SHORTWAVES EMBEDDED IN THE FLOW ARE HANDLED. A LEAD SHORTWAVE FEATURED BY THE ECMWF MOVES NORTHEAST THROUGH KS/MO EARLY THU MORNING FOLLOWED BY THE MAIN/STRONGER WESTERN SHORTWAVE AND COLD FRONT APPROACHING THE REGION FRI AND MOVING THROUGH EASTERN KS/MO LATE FRI NIGHT EARLY SAT MORNING. THE THU/FRI TIME PERIOD WOULD SEEM TO BE THE BEST OVERALL CHANCES FOR RAIN/TSTMS. BIG/HUGE DIFFERENCES IN THE MODELS DEVELOP WITH PLACEMENT OF A NORTHWEST FLOW UPPER SYSTEM...WITH THE GFS MUCH FARTHER SOUTH AND WEST WITH PLACEMENT VERSUS THE ECMWF...PROBABLY ON THE ORDER OF 1000 MILES BY MONDAY AFTERNOON. THE GFS PLACES A CLOSED LOW OVER KS/OK BY 00Z TUE WHILE THE ECMWF HAS A STRONGER CLOSED LOW OVER OHIO. THIS IS WHERE I PUNTED AND FOLLOWED FOLLOWED HPC GUIDANCE MORE CLOSELY. CONFIDENCE IS FAIRLY LOW EARLY NEXT WEEK. DSA && .AVIATION... FOR THE 1800 UTC KSGF/KJLN TAFS...VFR CEILINGS WILL SCATTER OUT AT TIMES THIS AFTERNOON. A SLOW MOVING COLD FRONT OVER EASTERN KS WILL LIKELY BECOME MORE ACTIVE LATE THIS AFTERNOON AND THIS EVENING WITH SOME SCATTERED CONVECTION MOVING INTO THE TAF SITES LATE TONIGHT AND TUE MORNING. DID NOT HIT THE LOWER CEILINGS TOO HARD...WITH ONLY MVFR CEILINGS IN LATER PERIODS TONIGHT WITH INCREASED LOW LEVEL MOISTURE AND RAIN POTENTIAL. TRENDS WILL NEED TO BE WATCHED. DSA && .SGF WATCHES/WARNINGS/ADVISORIES... MO...NONE. KS...NONE. && $$ mo