AREA FORECAST DISCUSSION...CORRECTED NATIONAL WEATHER SERVICE HANFORD CA 826 PM PST SUN JAN 21 2007 ADDED AVIATION SECTION .UPDATE...FOR THE CENTRAL CALIFORNIA INTERIOR...SATELLITE LOOPS SHOW A BAND OF HIGH CLOUDS MOVING ACROSS THE HANFORD WARNING/FORECAST AREA THIS EVENING...AS AN UPPER-LEVEL LOW DROPPING INTO ARIZONA PULLS THE ASSOCIATED TROUGH OVER THE SOUTHERN HALF OF CALIFORNIA SOUTHWARD. THIS IN TURN IS ALLOWING THE EAST-PACIFIC UPPER-LEVEL RIDGE TO BUILD INTO NORTHERN CALIFORNIA. HIGH TEMPERATURES ACROSS THE CENTRAL AND SOUTHERN SAN JOAQUIN VALLEY THIS AFTERNOON WERE IN THE MID 50S...AND RANGED FROM PERSISTENCE TO DOWN 3 DEGREES FROM SATURDAY/S HIGHS. THE 24-HOUR TEMPERATURE CHANGE ACROSS THE CENTRAL AND SOUTH VALLEY AT 03Z RANGED FROM DOWN 2 TO UP 3 DEGREES OVER 03Z SUNDAY...WITH A CHANGE IN DEWPOINT OF DOWN 3 TO UP 1 DEGREE. AS A RESULT...LOW TEMPERATURES MONDAY MORNING LIKELY WILL BE SIMILAR TO THIS MORNING...WHICH SAW LOWS RANGING FROM 25 AT HANFORD MUNICIPAL AIRPORT /KHJO/ TO 32 AT BAKERSFIELD AND LEMON COVE...AND 36 AT TAFT. VISALIA WAS UNDER 28 DEGREES FOR LESS THAN 40 MINUTES THIS MORNING...AND NAS LEMOORE WAS UNDER 28 DEGREES FOR LESS THAN AN HOUR. OF THE NORMALLY COLD SPOTS...MADERA MUNICIPAL AIRPORT WAS UNDER 28 DEGREES FOR LESS THAN 2 HOURS...WHILE HANFORD MUNICIPAL AIRPORT HAD 3 HOURS BELOW 28 DEGREES. /THE LOW AT WFO SAN JOAQUIN VALLEY-HANFORD WAS 27 DEGREES...2 DEGREES WARMER THAN THE AIRPORT./ BECAUSE OF RELATIVELY SHORT DURATIONS UNDER 28 DEGREES...EXCEPT FOR HANFORD AIRPORT...A WIDESPREAD FREEZE IS NOT EXPECTED AND THEREFORE WILL KEEP THE FROST ADVISORY IN PLACE. GUSTY NORTHEAST WINDS ALOFT CONTINUE OVER THE KERN COUNTY DESERTS... WITH GUSTS TO 45 MPH OVER THE CREST OF THE EL PASO MOUNTAINS AND LOCALLY INTO EAST-FACING CANYONS OF THE SOUTHERN SIERRA NEVADA. HOWEVER...THESE WINDS ARE NOT WORKING DOWN TO THE DESERT FLOOR EXCEPT LOCALLY NEAR INYOKERN...AND EVEN THESE GUSTS HAVE DIMINISHED SINCE THIS AFTERNOON. HOWEVER...COULD STILL SEE A FEW STRONG GUSTS THIS EVENING...AND BOTH THE 00Z NAM AND GFS CONTINUE TO FORECAST A STRONG OFFSHORE LOS ANGELES-TONOPAH SURFACE PRESSURE GRADIENT THROUGH 12Z...SO WILL NOT REMOVE GUSTS FROM THE DESERT FORECAST AT THIS TIME. THE 00Z MODELS ARE IN GOOD AGREEMENT WITH THE UPPER-LEVEL LOW CONTINUING TO DROP SOUTH INTO SONORA /IN NORTHERN MEXICO/ BY 00Z TUESDAY...WITH THE UPPER-LEVEL RIDGE BUILDING INTO CENTRAL CALIFORNIA. WITH THE RIDGE OVER THE REGION...EXPECT CONTINUED CLEAR SKIES AND LIGHT WINDS MONDAY NIGHT/TUESDAY MORNING IN THE CENTRAL AND SOUTHERN SAN JOAQUIN VALLEY. ALL THREE MOS GUIDANCES... FWC/MAV/MET...FORECAST LOWS TUESDAY MORNING IN FRESNO TO BE A DEGREE OR TWO ABOVE FREEZING. HOWEVER...MOS GUIDANCE HAS BEEN A FEW DEGREES TOO WARM AT NIGHT THE LAST FEW RUNS...SO EXPECT THE STRING OF SUB-32 LOWS COULD CONTINUE AT LEAST ONE MORE NIGHT. .AIR QUALITY ISSUES... THE VALLEY AIR DISTRICT HAS ISSUED THE FOLLOWING FIREPLACE/WOOD STOVE BURNING DECLARATION FOR MONDAY, JANUARY 22, 2007. WOOD BURNING IS PROHIBITED IN FRESNO COUNTY. WOOD BURNING IS DISCOURAGED IN KERN, KINGS, MADERA, MERCED AND TULARE COUNTIES. && .PREV DISCUSSION... /ISSUED 242 PM PST SUN JAN 21 2007/ SHORT TERM...TONIGHT THROUGH WEDNESDAY...WATER VAPOR SATELLITE IMAGERY ALONG WITH RUC80 UPPER AIR ANALYSIS NOW SHOWING THE CLOSED UPPER LOW OVER NORTHERN ARIZONA AND STILL TRACKING SOUTH TO SOUTHEAST. AS THIS UPPER LOW TRACK SOUTHWARD...WILL CONTINUE TO SEE THE CORE OF A +90KTS JET MAX PUSH INTO THE EASTERN SECTIONS OF THE DISTRICT. WHILE THE EAST SIDE OF THE SAN JOAQUIN VALLEY MAY BE SHELTERED...THE WEST SIDE ALONG THE DESERTS AND MOUNTAINS WILL SEE INCREASED WINDS THIS AFTERNOON AND EVENING. OTHER THEN THE WINDS...WILL MAINTAIN A DRY AND COLD FORECAST FOR TONIGHT AND EXPECT WINDS TO DIMINISH FOR ANOTHER NIGHT OF POSSIBLE FROST. THEREFORE...HAVE ISSUED A FROST ADVISORY FOR TONIGHT THROUGH MONDAY MORNING AS VALLEY TEMPERATURES FALL BE 32 DEG-F ONCE AGAIN. BY MONDAY...SHORT RANGE MODELS PLACE THE UPPER LOW OVER NORTHERN MEXICO WITH GOOD 500MB HEIGHT RISES OVER THE DISTRICT. WITH THIS...WILL EXPECT SLIGHT WARMING IN THE SHORT TERM AS 850MB TEMP/S RISE BY A DEG-C OR TWO. MODELS SHOW THE TILTED RIDGE AXIS SHIFTING MORE OVER THE WEST COAST WITH ADDITIONAL WARMING EXPECTED ON TUESDAY. AT THIS POINT...RIDGE BECOMES MORE OF A OMEGA BLOCKING PATTERN WITH DRY CONDITIONS EXPECTED INTO MID-WEEK AND THROUGH THE SHORT TERM. AS TEMPERATURES SLOW RISE...FROST WILL BECOME MORE PATCHY. LONG TERM...WEDNESDAY NIGHT THROUGH SUNDAY...MEDIUM RANGE MODELS REMAIN IN GOOD AGREEMENT THROUGH WEDNESDAY AND KEEP HIGH AMPLITUDE RIDGE PARKED OVER CA AND THE INTERMOUNTAIN WEST. THEREAFTER MODELS HAVING A DIFFICULT TIME SEPARATING NORTHERN AND SOUTHER STREAM JET ENERGY IN THE EAST PACIFIC. BETTER CONSISTENCY SHOWN BY THE ECMWF WITH THE 00Z RUN PREFERRED. THIS SOLUTION BRINGS AN UPPER TROUGH WELL OFF THE NORTH CALIFORNIA THURSDAY. THEN SLOWLY MOVING THE SYSTEM EAST OVER NORTH CALIFORNIA BY SATURDAY. WILL MAINTAIN A DRY FORECAST AND INCREASE CLOUD COVER AS PROG INDICATED LIMITED MOISTURE. ONSHORE FLOW SHOULD BRING A MARITIME AIR INTO CENTRAL CALIFORNIA. THIS WILL MODERATE TEMPERATURES RESULTING IN COOLER HIGHS AND WARMER LOWS. && .AVIATION...AREAS OF MVFR DUE TO HAZE CAN BE EXPECTED IN THE SAN JOAQUIN VALLEY. STRONG GUSTY WINDS ARE EXPECTED OVER THE TEHACHAPI MOUNTAIN PASSES AND MOJAVE DESERT. OTHERWISE...VFR CONDITIONS WILL PREVAIL ACROSS THE CENTRAL CA INTERIOR THROUGH 00Z TUESDAY. FOR SPECIFIC DETAILS...PLEASE REFER TO THE TAFS FOR KMCE...KFAT AND KBFL...AND TWEB ROUTES 421 AND 423. && AIR QUALITY ISSUES... THE VALLEY AIR DISTRICT HAS ISSUED THE FOLLOWING FIREPLACE/WOOD STOVE BURNING DECLARATION FOR MONDAY, JANUARY 22, 2007. WOOD BURNING IS PROHIBITED IN FRESNO COUNTY. WOOD BURNING IS DISCOURAGED IN KERN, KINGS, MADERA, MERCED AND TULARE COUNTIES. && .HNX WATCHES/WARNINGS/ADVISORIES... FROST ADVISORY FROM MIDNIGHT TONIGHT TO 9 AM PST MONDAY FOR THE CENTRAL AND SOUTHERN SAN JOAQUIN VALLEY /CAZ089>092/. && $$ SANGER/MOLINA/MV WEATHER.GOV/HANFORD ca AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE HANFORD CA 826 PM PST SUN JAN 21 2007 .UPDATE...FOR THE CENTRAL CALIFORNIA INTERIOR...SATELLITE LOOPS SHOW A BAND OF HIGH CLOUDS MOVING ACROSS THE HANFORD WARNING/FORECAST AREA THIS EVENING...AS AN UPPER-LEVEL LOW DROPPING INTO ARIZONA PULLS THE ASSOCIATED TROUGH OVER THE SOUTHERN HALF OF CALIFORNIA SOUTHWARD. THIS IN TURN IS ALLOWING THE EAST-PACIFIC UPPER-LEVEL RIDGE TO BUILD INTO NORTHERN CALIFORNIA. HIGH TEMPERATURES ACROSS THE CENTRAL AND SOUTHERN SAN JOAQUIN VALLEY THIS AFTERNOON WERE IN THE MID 50S...AND RANGED FROM PERSISTENCE TO DOWN 3 DEGREES FROM SATURDAY/S HIGHS. THE 24-HOUR TEMPERATURE CHANGE ACROSS THE CENTRAL AND SOUTH VALLEY AT 03Z RANGED FROM DOWN 2 TO UP 3 DEGREES OVER 03Z SUNDAY...WITH A CHANGE IN DEWPOINT OF DOWN 3 TO UP 1 DEGREE. AS A RESULT...LOW TEMPERATURES MONDAY MORNING LIKELY WILL BE SIMILAR TO THIS MORNING...WHICH SAW LOWS RANGING FROM 25 AT HANFORD MUNICIPAL AIRPORT /KHJO/ TO 32 AT BAKERSFIELD AND LEMON COVE...AND 36 AT TAFT. VISALIA WAS UNDER 28 DEGREES FOR LESS THAN 40 MINUTES THIS MORNING...AND NAS LEMOORE WAS UNDER 28 DEGREES FOR LESS THAN AN HOUR. OF THE NORMALLY COLD SPOTS...MADERA MUNICIPAL AIRPORT WAS UNDER 28 DEGREES FOR LESS THAN 2 HOURS...WHILE HANFORD MUNICIPAL AIRPORT HAD 3 HOURS BELOW 28 DEGREES. /THE LOW AT WFO SAN JOAQUIN VALLEY-HANFORD WAS 27 DEGREES...2 DEGREES WARMER THAN THE AIRPORT./ BECAUSE OF RELATIVELY SHORT DURATIONS UNDER 28 DEGREES...EXCEPT FOR HANFORD AIRPORT...A WIDESPREAD FREEZE IS NOT EXPECTED AND THEREFORE WILL KEEP THE FROST ADVISORY IN PLACE. GUSTY NORTHEAST WINDS ALOFT CONTINUE OVER THE KERN COUNTY DESERTS... WITH GUSTS TO 45 MPH OVER THE CREST OF THE EL PASO MOUNTAINS AND LOCALLY INTO EAST-FACING CANYONS OF THE SOUTHERN SIERRA NEVADA. HOWEVER...THESE WINDS ARE NOT WORKING DOWN TO THE DESERT FLOOR EXCEPT LOCALLY NEAR INYOKERN...AND EVEN THESE GUSTS HAVE DIMINISHED SINCE THIS AFTERNOON. HOWEVER...COULD STILL SEE A FEW STRONG GUSTS THIS EVENING...AND BOTH THE 00Z NAM AND GFS CONTINUE TO FORECAST A STRONG OFFSHORE LOS ANGELES-TONOPAH SURFACE PRESSURE GRADIENT THROUGH 12Z...SO WILL NOT REMOVE GUSTS FROM THE DESERT FORECAST AT THIS TIME. THE 00Z MODELS ARE IN GOOD AGREEMENT WITH THE UPPER-LEVEL LOW CONTINUING TO DROP SOUTH INTO SONORA /IN NORTHERN MEXICO/ BY 00Z TUESDAY...WITH THE UPPER-LEVEL RIDGE BUILDING INTO CENTRAL CALIFORNIA. WITH THE RIDGE OVER THE REGION...EXPECT CONTINUED CLEAR SKIES AND LIGHT WINDS MONDAY NIGHT/TUESDAY MORNING IN THE CENTRAL AND SOUTHERN SAN JOAQUIN VALLEY. ALL THREE MOS GUIDANCES... FWC/MAV/MET...FORECAST LOWS TUESDAY MORNING IN FRESNO TO BE A DEGREE OR TWO ABOVE FREEZING. HOWEVER...MOS GUIDANCE HAS BEEN A FEW DEGREES TOO WARM AT NIGHT THE LAST FEW RUNS...SO EXPECT THE STRING OF SUB-32 LOWS COULD CONTINUE AT LEAST ONE MORE NIGHT. .AIR QUALITY ISSUES... THE VALLEY AIR DISTRICT HAS ISSUED THE FOLLOWING FIREPLACE/WOOD STOVE BURNING DECLARATION FOR MONDAY, JANUARY 22, 2007. WOOD BURNING IS PROHIBITED IN FRESNO COUNTY. WOOD BURNING IS DISCOURAGED IN KERN, KINGS, MADERA, MERCED AND TULARE COUNTIES. && .PREV DISCUSSION... /ISSUED 242 PM PST SUN JAN 21 2007/ SHORT TERM...TONIGHT THROUGH WEDNESDAY...WATER VAPOR SATELLITE IMAGERY ALONG WITH RUC80 UPPER AIR ANALYSIS NOW SHOWING THE CLOSED UPPER LOW OVER NORTHERN ARIZONA AND STILL TRACKING SOUTH TO SOUTHEAST. AS THIS UPPER LOW TRACK SOUTHWARD...WILL CONTINUE TO SEE THE CORE OF A +90KTS JET MAX PUSH INTO THE EASTERN SECTIONS OF THE DISTRICT. WHILE THE EAST SIDE OF THE SAN JOAQUIN VALLEY MAY BE SHELTERED...THE WEST SIDE ALONG THE DESERTS AND MOUNTAINS WILL SEE INCREASED WINDS THIS AFTERNOON AND EVENING. OTHER THEN THE WINDS...WILL MAINTAIN A DRY AND COLD FORECAST FOR TONIGHT AND EXPECT WINDS TO DIMINISH FOR ANOTHER NIGHT OF POSSIBLE FROST. THEREFORE...HAVE ISSUED A FROST ADVISORY FOR TONIGHT THROUGH MONDAY MORNING AS VALLEY TEMPERATURES FALL BE 32 DEG-F ONCE AGAIN. BY MONDAY...SHORT RANGE MODELS PLACE THE UPPER LOW OVER NORTHERN MEXICO WITH GOOD 500MB HEIGHT RISES OVER THE DISTRICT. WITH THIS...WILL EXPECT SLIGHT WARMING IN THE SHORT TERM AS 850MB TEMP/S RISE BY A DEG-C OR TWO. MODELS SHOW THE TILTED RIDGE AXIS SHIFTING MORE OVER THE WEST COAST WITH ADDITIONAL WARMING EXPECTED ON TUESDAY. AT THIS POINT...RIDGE BECOMES MORE OF A OMEGA BLOCKING PATTERN WITH DRY CONDITIONS EXPECTED INTO MID-WEEK AND THROUGH THE SHORT TERM. AS TEMPERATURES SLOW RISE...FROST WILL BECOME MORE PATCHY. LONG TERM...WEDNESDAY NIGHT THROUGH SUNDAY...MEDIUM RANGE MODELS REMAIN IN GOOD AGREEMENT THROUGH WEDNESDAY AND KEEP HIGH AMPLITUDE RIDGE PARKED OVER CA AND THE INTERMOUNTAIN WEST. THEREAFTER MODELS HAVING A DIFFICULT TIME SEPARATING NORTHERN AND SOUTHER STREAM JET ENERGY IN THE EAST PACIFIC. BETTER CONSISTENCY SHOWN BY THE ECMWF WITH THE 00Z RUN PREFERRED. THIS SOLUTION BRINGS AN UPPER TROUGH WELL OFF THE NORTH CALIFORNIA THURSDAY. THEN SLOWLY MOVING THE SYSTEM EAST OVER NORTH CALIFORNIA BY SATURDAY. WILL MAINTAIN A DRY FORECAST AND INCREASE CLOUD COVER AS PROG INDICATED LIMITED MOISTURE. ONSHORE FLOW SHOULD BRING A MARITIME AIR INTO CENTRAL CALIFORNIA. THIS WILL MODERATE TEMPERATURES RESULTING IN COOLER HIGHS AND WARMER LOWS. AIR QUALITY ISSUES... THE VALLEY AIR DISTRICT HAS ISSUED THE FOLLOWING FIREPLACE/WOOD STOVE BURNING DECLARATION FOR MONDAY, JANUARY 22, 2007. WOOD BURNING IS PROHIBITED IN FRESNO COUNTY. WOOD BURNING IS DISCOURAGED IN KERN, KINGS, MADERA, MERCED AND TULARE COUNTIES. && .HNX WATCHES/WARNINGS/ADVISORIES... FROST ADVISORY FROM MIDNIGHT TONIGHT TO 9 AM PST MONDAY FOR THE CENTRAL AND SOUTHERN SAN JOAQUIN VALLEY /CAZ089>092/. && $$ SANGER/MOLINA/MV WEATHER.GOV/HANFORD ca AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE HANFORD CA 242 PM PST SUN JAN 21 2007 .SHORT TERM...TONIGHT THROUGH WEDNESDAY...WATER VAPOR SATELLITE IMAGERY ALONG WITH RUC80 UPPER AIR ANALYSIS NOW SHOWING THE CLOSED UPPER LOW OVER NORTHERN ARIZONA AND STILL TRACKING SOUTH TO SOUTHEAST. AS THIS UPPER LOW TRACK SOUTHWARD...WILL CONTINUE TO SEE THE CORE OF A +90KTS JET MAX PUSH INTO THE EASTERN SECTIONS OF THE DISTRICT. WHILE THE EAST SIDE OF THE SAN JOAQUIN VALLEY MAY BE SHELTERED...THE WEST SIDE ALONG THE DESERTS AND MOUNTAINS WILL SEE INCREASED WINDS THIS AFTERNOON AND EVENING. OTHER THEN THE WINDS...WILL MAINTAIN A DRY AND COLD FORECAST FOR TONIGHT AND EXPECT WINDS TO DIMINISH FOR ANOTHER NIGHT OF POSSIBLE FROST. THEREFORE...HAVE ISSUED A FROST ADVISORY FOR TONIGHT THROUGH MONDAY MORNING AS VALLEY TEMPERATURES FALL BE 32 DEG-F ONCE AGAIN. BY MONDAY...SHORT RANGE MODELS PLACE THE UPPER LOW OVER NORTHERN MEXICO WITH GOOD 500MB HEIGHT RISES OVER THE DISTRICT. WITH THIS...WILL EXPECT SLIGHT WARMING IN THE SHORT TERM AS 850MB TEMP/S RISE BY A DEG-C OR TWO. MODELS SHOW THE TILTED RIDGE AXIS SHIFTING MORE OVER THE WEST COAST WITH ADDITIONAL WARMING EXPECTED ON TUESDAY. AT THIS POINT...RIDGE BECOMES MORE OF A OMEGA BLOCKING PATTERN WITH DRY CONDITIONS EXPECTED INTO MID-WEEK AND THROUGH THE SHORT TERM. AS TEMPERATURES SLOW RISE...FROST WILL BECOME MORE PATCHY. .LONG TERM...WEDNESDAY NIGHT THROUGH SUNDAY...MEDIUM RANGE MODELS REMAIN IN GOOD AGREEMENT THROUGH WEDNESDAY AND KEEP HIGH AMPLITUDE RIDGE PARKED OVER CA AND THE INTERMOUNTAIN WEST. THEREAFTER MODELS HAVING A DIFFICULT TIME SEPARATING NORTHERN AND SOUTHER STREAM JET ENERGY IN THE EAST PACIFIC. BETTER CONSISTENCY SHOWN BY THE ECMWF WITH THE 00Z RUN PREFERRED. THIS SOLUTION BRINGS AN UPPER TROUGH WELL OFF THE NORTH CALIFORNIA THURSDAY. THEN SLOWLY MOVING THE SYSTEM EAST OVER NORTH CALIFORNIA BY SATURDAY. WILL MAINTAIN A DRY FORECAST AND INCREASE CLOUD COVER AS PROG INDICATED LIMITED MOISTURE. ONSHORE FLOW SHOULD BRING A MARITIME AIR INTO CENTRAL CALIFORNIA. THIS WILL MODERATE TEMPERATURES RESULTING IN COOLER HIGHS AND WARMER LOWS. && .AIR QUALITY ISSUES... THE VALLEY AIR DISTRICT HAS ISSUED THE FOLLOWING FIREPLACE/WOOD STOVE BURNING DECLARATION FOR MONDAY, JANUARY 22, 2007. WOOD BURNING IS PROHIBITED IN FRESNO COUNTY. WOOD BURNING IS DISCOURAGED IN KERN, KINGS, MADERA, MERCED AND TULARE COUNTIES. && .HNX WATCHES/WARNINGS/ADVISORIES... FROST ADVISORY FROM MIDNIGHT TONIGHT TO 9 AM PST MONDAY FOR THE CENTRAL AND SOUTHERN SAN JOAQIUN VALLEY /CAZ089>092/. && $$ MOLINA/MV WEATHER.GOV/HANFORD ca AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE PUEBLO CO 334 AM MST MON JAN 22 2007 .SHORT TERM... (TODAY AND TONIGHT) MAIN SHORT TERM CONCERN IS TEMPERATURES ACROSS THE REGION. CURRENT WATER VAPOR IMAGERY AND RUC UPPER AIR ANALYSIS INDICATING INCREASING NORTHERLY FLOW ALOFT ACROSS THE STATE WITH AN UPPER TROUGH ACROSS THE NORTHERN HIGH PLAINS MOVING EAST INTO THE UPPER MIDWEST AS UPPER LEVEL RIDGING BUILDS ACROSS THE WEST COAST AND INTO THE GREAT BASIN REGION. WATER VAPOR IMAGERY ALSO INDICATING SOME MID AND UPPER LEVEL MOISTURE AND JET CORE MOVING DOWN THE BACK SIDE OF RIDGE ACROSS THE EASTERN GREAT BASIN...WHICH IS CONTINUING TO PUSH AN UPPER LOW ACROSS SOUTH CENTRAL ARIZONA FURTHER SOUTH INTO OLD MEXICO ATTM. AT THE SFC...COOL HIGH PRESSURE ACROSS THE CENTRAL HIGH PLAINS CONTINUES TO BUILD SOUTH AND EAST INTO THE SOUTHERN HIGH PLAINS...WITH SATELLITE AND FOG PRODUCT INDICATING MAINLY CLEAR AND COLD CONDITIONS ACROSS THE REGION WITH A FEW PATCHES OF STRATUS MAINLY ACROSS THE EASTERN PLAINS ATTM. TODAY...NORTHERLY FLOW CONTINUES TO INCREASE ALOFT AS UPPER RIDGE CONTINUES TO BUILD EAST. H7 TEMPS INCREASE AROUND 2C TODAY AS HEIGHTS BUILD FROM WEST TO EAST...WITH SOUNDINGS INDICATING WEAK TO MODERATE SFC-H7 INVERSIONS IN PLACE ACROSS THE PLAINS. WITH A WEAK SFC GRADIENT AND LOW SUN ANGLE...BELIEVE THERE WILL NOT BE ENOUGH MIXING TO BREAK INVERSIONS...AND HAVE CONTINUED TREND OF GOING AOB GUIDANCE TEMPS TODAY...ESPECIALLY ACROSS THE LOWER ARKANSAS AND SAN LUIS VALLEYS. WITH DRIER AIR IN THE NORTHERLY FLOW CONTINUING TO MOVE INTO THE REGION...PATCHY STRATUS TO CONTINUE TO DISSIPATE THIS MORNING WITH MOSTLY SUNNY CONDITIONS PREVAILING THROUGHOUT THE DAY...WHICH SHOULD HELP MAKE IT FEEL WARMER THAN IT ACTUALLY IS TODAY. TONIGHT...BRISK NORTHERLY FLOW ALOFT TO CONTINUE WITH HEIGHTS AND TEMPERATURES INCREASING ALOFT AS RIDGING BUILDS EAST. WITH THE WARMER AIR ALOFT...TEMPS TO BE A CHALLENGE AS NOCTURNAL INVERSIONS SET UP. WITH WEAK SFC WINDS AND MAINLY CLEAR SKIES...HAVE GONE AOB COOLEST GUIDANCE FOR LOWS ACROSS THE LOWER ELEVATIONS...THOUGH HAVE RAISED TEMPS ACROSS THE HIGHER TERRAIN AND ADJACENT FOOTHILLS. -MW .LONG TERM... (TUESDAY THROUGH SUNDAY) MAINLY JUST TEMPERATURE CONCERNS THROUGH FRIDAY...AS UPPER RIDGE BUILDS OVER THE WESTERN U.S. MAIN QUESTION IS HOW MUCH OF THE RATHER SUBSTANTIAL WARMING ALOFT REACHES GROUND LEVEL...ESPECIALLY OVER THE SNOW COVERED EASTERN PLAINS. FOR TUESDAY...FLOW ALOFT REMAINS MOSTLY NLY...WITH VERY WEAK LEE TROUGH AND WLY WINDS AT THE SURFACE. SHOULD SEE TEMPS WELL INTO THE 40S ALONG THE EAST MOUNTAIN SLOPES AND I-25 CORRIDOR...WHILE AREAS FARTHER EAST STRUGGLE INTO THE 30S. S/W TROUGH DIVING SOUTH INTO THE MIDWEST ON WED SHOULD HAVE LITTLE IMPACT ON LOCAL WEATHER AS LEE TROUGH AND DOWNSLOPE FLOW REDEVELOPS BY AFTERNOON. 10-15F DIFFERENCE BETWEEN MAV AND MET FOR TUESDAY HIGHS...SO SPLIT THE DIFFERENCE OVER THE MOUNTAINS AND ALONG I-25...STILL UNDERCUTTING GUIDANCE OVER THE SNOW COVERED EAST. 700 MB TEMPS PEAK ON WEDNESDAY...WITH MOST OF THE AREA CLIMBING ABOVE 0C FOR A BRIEF TIME. SHOULD SEE SOME 50F READINGS APPEAR ALONG THE I-25 CORRIDOR...BUT WITH FAIRLY LIGHT SURFACE WINDS...AREAS FARTHER EAST WILL REMAIN COOL. DISREGARDED THE GFS SOLUTION OF BRINGING THE OLD UPPER LOW BACK NORTH ACROSS SOUTHEAST COLORADO ON FRIDAY...BUT WILL HAVE TO KEEP AN EYE ON THIS POSSIBILITY THE NEXT FEW DAYS. LEFT SAT/SUN GRIDS UNTOUCHED...THOUGH WITH LATEST GFS AND ECMWF COMING INTO BETTER AGREEMENT BRINGING A NEW CHUNK OF ARCTIC AIR INTO THE PLAINS FRIDAY NIGHT/SATURDAY...SUSPECT WE`LL BE MAKING SOME DOWNWARD ADJUSTMENTS TO TEMPS LATER THIS WEEK. --PETERSEN && .PUB WATCHES/WARNINGS/ADVISORIES... NONE. && $$ 23/10 co AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE PUEBLO CO 647 PM MST SUN JAN 21 2007 .UPDATE... THE SNOW AND WIND HAVE BEEN WINDING DOWN ACROSS MUCH OF CENTRAL... SOUTH CENTRAL...CENTRAL...AND SOUTHEAST COLORADO EARLY THIS EVENING. THERE ARE A FEW SNOW SHOWERS ACROSS THE LOWER AR RIVER VALLEY. IT APPEARS THE POTENTIAL HAZARDOUS WINTER WEATHER THREAT HAS DIMINISHED...SO WILL CANCEL ALL HEADLINES. LATEST WATER VAPOR IMAGERY AND RUC MODEL UPPER AIR ANALYSES SHOWED CLOSED LOW DRIFTING SOUTHWESTWARD INTO AZ WITH A WEAK TROUGH ACROSS NORTHEAST CO AND SOUTHERN CO IN-BETWEEN THE TWO SYSTEMS. SHORT- RANGE MODELS ARE INDICATING THE SYNOPTIC SCALE ASCENT WILL WEAKEN CONSIDERABLY LATER TONIGHT AND LEAD TO A POTENTIAL CLEARING SKY. A LITTLE CONCERNED ABOUT SHALLOW DENSE GROUND FOG DEVELOPING IN LOW LYING AREAS LIKE THE SAN LUIS VALLEY AND LOWER AR RIVER VALLEY GIVEN RELATIVELY HIGH SFC-PBL HUMIDITY LEVELS AND DEW POINTS INCREASING JUST OFF THE GROUND PER LAPS AND 12KM WRF SOUNDINGS. CLOUD COVER AND ANY WIND ALOFT COULD KEEP THE FOG FROM FORMING. PLAN TO LEAVE FOG OUT FOR NOW...BUT WILL CONTINUE TO MONITOR. METZE && .PUB WATCHES/WARNINGS/ADVISORIES... NONE. && $$ co AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE ALBANY NY 418 PM EST TUE JAN 23 2007 .SYNOPSIS... A COLD FRONT WILL APPROACH FROM THE UPPER GREAT LAKES REGION AND SOUTHEASTERN CANADA OVERNIGHT. A STRONG UPPER LEVEL DISTURBANCE AHEAD THE FRONT WILL GENERATE SIGNIFICANT LAKE ENHANCED SNOWFALL FOR THE WESTERN ADIRONDACKS. THE COLD FRONT WILL PASS THROUGH THE REGION EARLY WEDNESDAY WITH SOME SCATTERED SNOW SHOWERS AND FLURRIES MAINLY FROM THE CAPITAL REGION NORTH AND WEST. A WEAK AREA OF LOW PRESSURE AND AN ARCTIC COLD FRONT WILL APPROACH FROM THE CENTRAL GREAT LAKES REGION AND MIDWEST WEDNESDAY. THIS ARCTIC FRONT WILL PASS THROUGH THE REGION THURSDAY WITH THE COLDEST AIR OF THE SEASON. A FRIGID AIR MASS WILL BE OVER THE REGION THURSDAY NIGHT THROUGH FRIDAY WITH WIND CHILL VALUES BELOW ZERO. BIG PICTURE...A BROAD 500 MB LONG WAVE TROUGH IS ANCHORED IN PLACE OVER THE CNTRL-ERN PORTIONS OF CANADA...THE NORTHEAST...GREAT LAKES REGION AND MIDWEST. A 500 MB RIDGE REMAINS OVER THE WEST COAST AND WRN CANADA. A +PNA/-NAO REGIME WILL CONTINUE (MEAN 500 MB LONG WAVE TROUGH IN THE EAST AND MEAN 500 MB LONG WAVE RIDGE IN THE WEST) FOR THE NEXT SEVERAL DAYS. IN THE WATER VAPOR LOOP...A CUTOFF CONTINUES TO MEANDER SLOWLY EAST NEAR THE WRN PAN HANDLE OF TX. GULF AND PACIFIC MOISTURE IS BEING SHUNTED EASTWARD OVER THE SUNBELT DUE TO THE STRONG UPPER LEVEL TROUGH SITUATED NORTH. THE SOURCE OF AIR MASSES WILL CONTINUE TO BE FROM NRN-CNTRL CANADA AND THE ARCTIC REGION FOR THE NORTHEAST THROUGH THE WEEKEND. THE BROAD POLAR VORTEX WILL DRIFT SOUTH OVER EXTREME SOUTHEAST CANADA AND THE NORTHEAST THU INTO FRIDAY WITH BITTERLY COLD AIR. && .SHORT TERM /TONIGHT THROUGH FRIDAY/... TONIGHT...CURRENTLY AT 21Z...LAKE ENHANCED SNOWFALL ACTIVITY IS ONGOING OVER WRN-CNTRL NY PUSHING EASTWARD. THE LATEST 40KM RUC SHOWS A POTENT H500 SHORT WAVE MOVING EAST OF LAKE HURON AND GEORGIAN BAY. THIS SHORT WAVE COUPLED WITH SOME ISENTROPIC LIFT IS HELPING GENERATE SOME STRONG UPWARD MOTION TO PRODUCE THE SNOWFALL. WE CAREFULLY VIEWED THE 12Z NAM/WRF SOUNDINGS IN BUFKIT UPSTREAM AT KSYR...KUCA...AND KSPC /SPECULATOR/ FOR THE OVERNIGHT PERIOD. BASED ON A LAKE ONTARIO TEMPERATURE OF 38F...WE ARE MAINLY WORKING WITH CONDITIONAL INSTABILITY. THE 850 MB FLOW/TRAJECTORY STARTS OUT 260-270 DEGREES EARLY ON...THEN TOWARDS MIDNIGHT THE WINDS VEER TO ABOUT 280-290 DEGREES. ANY WEAK INVERSION APPEARS TO BE AROUND 8-10 KFT. HOWEVER...AS WE APPROACH DAYBREAK TOMORROW /12Z/...A SIGNIFICANT FRONTAL INVERSION DEVELOPS AROUND 5 KFT. WE BELIEVE THIS CAP WILL BE ENOUGH TO FURTHER INHIBIT THE LAKE ACTIVITY. QPF FROM THE NAM/WRF12 IS ABOUT ONE TO TWO TENTHS OF AN INCH OVER THE WRN ADIRONDACKS. WE ARE EXPECTING SNOW RATIOS OF 20-25:1. SO OVERNIGHT...WE HAVE 4-8 INCHES FORECASTED FOR NRN HERKIMER COUNTY AND 3-6 INCHES FOR HAMILTON COUNTY. THE LAKE BAND APPEARS IT WILL SHIFT FAR ENOUGH SOUTH TO IMPACT THE WRN-CNTRL MOHAWK VALLEY...SO WE WILL HAVE 2-4" THERE. FURTHER EAST...WE HAVE SLIGHT CHANCE AND LOW CHANCE VALUES WITH ANY LIGHT SNOW SHOWERS THAT MAKE THEIR WAY INTO THE CAPITAL REGION AND POINTS NORTH. TOMORROW...AS ALLUDED TO IN THE PREVIOUS SECTION. LAKE ENHANCED SNOW SHOWER ACTIVITY SHOULD DIMINISH IN THE WESTERN EXTREME OF THE FCST AREA BY NOON. A COLD FRONT WILL PASS THROUGH THE REGION IN THE LATE MORNING AND EARLY PM. COLD AIR ADVECTION WILL FOLLOW WITH 850 TEMPS FALLING BELOW -15C NORTH OF ALY. WE MAY DOWNSLOPE HERE WITH THE W/NW WINDS TO ALLOW TEMPS REACH 30-35F FROM THE CAPITAL DISTRICT SOUTH. WE TAILORED THE POPS DOWN WED PM...AND PLACED SCATTERED FLURRIES OVER THE WRN EXTREME OF THE FORECAST AREA. WED NIGHT...COLD AIR ADVECTION CONTINUES ACROSS THE FCST AREA WITH TEMPS FALLING BELOW ZERO NORTH OF THE CAPITAL REGION AND SINGLE DIGITS AND LOWER TEENS TO THE SOUTH. THE SHORT RANGE GUIDANCE SHOWS A VORT MAX WITH VERY WEAK ISENTROPIC LIFT APPROACHING BTWN 06Z-12Z THU. THE LOW LEVEL FLOW STARTS TO BACK AND SOME SCT SNOW SHOWERS MAY SNEAK INTO THE LOWER CATSKILLS...CNTRL MOHAWK VALLEY AND WRN ADIRONDACKS. WE PLACED SOME LOW CHANCE AND SLIGHT CHANCE POPS IN. WIND CHILL VALUES WILL BE VERY CLOSE TO ADVISORY LEVELS OVER THE SRN ADIRONDACKS...AND THE LAKE GEORGE REGION. THU....AN ARCTIC COLD FRONT MOVES THROUGH THE REGION IN THE LATE MORNING AND EARLY PM. A CHUNK OF -20C TO -25C AIR AT 850 MB MOVES INTO THE FCST AREA FROM THE CAPITAL REGION...MOHAWK VALLEY...AND BERKSHIRES NORTH. WE TRIED TO HAVE HAVE TEMPS PEAK AROUND NOONTIME AND FALL THROUGHOUT THE DAY. FROM THE CAPITAL REGION NORTH HIGHS WILL BE 10-20F...PTS SOUTH WILL BE IN THE LOWER 20S. THIS BOUNDARY WILL PRODUCE SCATTERED SNOW SHOWERS AND FLURRIES ACROSS THE FORECAST AREA...WITH THE BETTER FORCING WEST OF THE HUDSON RIVER VALLEY. THU NIGHT AND FRI...WELL...ALY MAY REACH ZERO FOR THE FIRST TIME...SINCE FEB 2 2005. MOST LOCATIONS WILL BE WELL BELOW ZERO FROM THE CAPITAL REGION NORTH AND WEST. 850 MB WILL BE -25C TO -30C OVER THE REGION. WIND CHILLS OF 15 TO 35 DEGREES BELOW ZERO MAY BE POSSIBLE. WINDS WILL BE 10-20 MPH FROM THE NW. WE WILL HIGHLIGHT THIS POSSIBILITY IN THE HAZARDOUS WEATHER OUTLOOK. WIND CHILL ADVISORIES AND WARNINGS MAY BE POSSIBLE THU NIGHT/FRI MORNING. FRIDAY...THE REGION WILL BE IN THE ICEBOX WITH 1000-500 MB THICKNESSES OF 490-500 DECAMETERS OVER THE REGION STARTING THE DAY. WE WENT WITH HIGHS CLOSE TO THE 12Z MEXMOS GUIDANCE HERE. THE FRIGID UPPER LEVEL TROUGH DRIFTS EAST OF THE REGION DURING THE DAY. TEMPS WILL BE IN SINGLE DIGITS OVER THE MTNS AND POINTS NORTH. LOWER TO MID TEENS WILL BE COMMON IN THE VALLEY LOCATIONS. THERE MAYBE A FEW FLURRIES AROUND...BUT AT THIS POINT WE KEPT IT DRY. && .LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/... THE LONG TERM PORTION OF THE FORECAST FEATURES MORE BELOW NORMAL TEMPERATURES AND POSSIBLE LIGHT SNOW EVENTS. THE LONG WAVE TROUGH REMAINS FIRMLY LOCKED IN PLACE WITH CLIPPER LOWS ROTATING AROUND THE POLAR VORTEX. IT IS DIFFICULT/CHALLENGING TO PINPOINT THE BEST CHANCES FOR THE LIGHT SNOW EVENTS BASED ON THE SPEED OF THE IMPULSES. WE PERUSED THE LAST FEW RUNS OF THE GFS...CAN GGEM...ECMWF...THE 06Z MREFS...AND THE LATEST HPC GRAPHICS. THE HPC SOLUTION WAS WELL ACCEPTED WITH SOME MINOR CHANGES ON TEMPS FOR HIGHS ON SAT...AND THE TRENDING IN OF POPS FOR THE FIRST LIGHT SNOWFALL SAT PM-SAT NIGHT. FRIDAY NIGHT...A WEAK RIDGE OF HIGH PRESSURE BUILDS IN FROM THE LOWER MID ATLANTIC WITH WARM AIR ADVECTION OCCURRING AT H850. SOME SCT -SHSN ARE POSSIBLE SAT. WE WENT WITH SLIGHT CHANCE VALUES FROM THE HUDSON RIVER VALLEY EAST AND LOW CHANCE VALUES WEST. SAT NIGHT INTO SUNDAY...WE FOLLOWED HPC AND THE MEDIUM RANGE GUIDANCE WITH THE BEST CHANCES OF LIGHT SNOW AHEAD OF THE CLIPPER LOW PRESSURE SYSTEM AND THE COLD FRONT. IF THE SYSTEM CLEARS ERN NY AND WRN NEW ENGLAND EARLY IN THE DAY ON SUNDAY...THEN TEMPS MIGHT FALL IN THE AFTERNOON WITH THE STRONG COLD AIR ADVECTION IN THE WAKE OF THE SYSTEM. SUN NIGHT INTO MONDAY...H500 POLAR VORTEX REMAINS OVER THE ERN ONTARIO/WRN QUEBEC BORDER WITH A NW FLOW FLOW OF ARCTIC AIR FUNNELING ACROSS THE REGION. SOME LAKE EFFECT SNOW SHOWERS WILL BE POSSIBLE MAINLY FOR LOCATIONS WEST/NORTHWEST OF THE CAPITAL REGION. MONDAY NIGHT INTO TUESDAY...ANOTHER CLIPPER APPROACHES FROM THE UPPER GREAT LAKES REGION AND SRN ONTARIO WITH ANOTHER BOUT OF LIGHT SNOW POSSIBLE. THE BEST CHANCE OF WIDESPREAD LIGHT SNOW ACROSS THE FCST AREA LOOKS TO BE DURING THE DAY ON TUESDAY AT THIS POINT. && .AVIATION /20Z-18Z/...MAINLY VFR CONDITIONS ARE EXPECTED IN THE HUDSON VALLEY THROUGH 18Z WEDNESDAY. THE EXCEPTION WILL BE AT KGFL AND KALB WHERE OCCASIONAL MVFR CONDITIONS WILL PERSIST THROUGH 21Z AND AGAIN AFTER 14Z. VISIBILITIES OF P6SM ARE EXPECTED THROUGH THE PERIOD WITH SCT-BKN025-035 BKN-OVC120 THROUGH THIS EVENING THEN BKN035 OVC060 THROUGH MUCH OF THE REMAINDER OF THE PERIOD. LIGHT SNOW SHOWERS ARE POSSIBLE FROM EARLY THIS EVENING UNTIL THE END OF THE PERIOD AT KGFL AND KALB IN ADVANCE OF AN ARCTIC FRONT AND ALSO AS A RESULT OF LAKE EFFECT ACTIVITY DOWNWIND OF LAKE ONTARIO. && .HYDROLOGY...AT THIS POINT IN TIME NO LIQUID PRECIPITATION IS EXPECTED DURING THE NEXT WEEK AND SNOWFALL AMOUNTS ARE EXPECTED TO BE MAINLY LIGHT PRIMARILY ASSOCIATED WITH CLIPPER TYPE SYSTEMS...ALTHOUGH THERE WILL BE SOME SIGNIFICANT LAKE EFFECT SNOW TONIGHT DOWNWIND OF LAKE ONTARIO. EACH SYSTEM WILL USHER IN MORE ARCTIC AIR. THE RESULT OF THE VERY COLD AIR FOR MUCH OF THE WEEK WILL BE A SIGNIFICANT INCREASE IN ICE THICKNESS ON MANY AREA BODIES OF WATER. MANY RIVER GAGES ARE ALREADY SHOWING SIGNS OF ICE EFFECTS AND DESPITE THE LATE START TO THE ARRIVAL OF THE COLD AIR THERE IS STILL PLENTY OF TIME LEFT IN THE WINTER SEASON FOR SIGNIFICANT ICE FORMATION ON RIVERS AND STREAMS. && .ALY WATCHES/WARNINGS/ADVISORIES... CT...NONE. MA...NONE. NY...LAKE EFFECT SNOW ADVISORY FROM 6 PM THIS EVENING TO 6 AM EST WEDNESDAY FOR NYZ032-033. VT...NONE. && $$ SYNOPSIS...WASULA SHORT TERM...WASULA LONG TERM...WASULA AVIATION...11 HYDROLOGY...11 ct AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CHARLESTON SC 934 PM EST SUN JAN 21 2007 .SHORT TERM /TONIGHT/...Q-STNRY FNTL BNDRY REMAINS ANCHORED ACROSS THE FAR NRN STRETCHES OF THE FCST AREA THIS EVNG...EXTENDING FROM MILLEN THROUGH WALTERBORO TO JUST N OF KCHS TO A PSN NEAR THE SOUTH SANTEE RIVER ENTRANCE PER MESONET/ASOS OBSERVATIONS. JUST N OF THE FNT TEMPS ARE IN THE LWR-MID 50S /INCLUDING MILLEN... WALTERBORO...HARLEYVILLE...PINEVILLE AND WITHERBEE/ WHILE FARTHER S LWR-MID 60S ARE COMMON ALL THE WAY TO THE COAST. DOUBT THE FNT WL MAKE MUCH INLAND HEADWAY TNGT AS WDSPRD PCPN FALLING INTO THE CAD WEDGE IN PLACE ACROSS SC MIDLANDS SHOULD KEEP THE FNT NEARLY STNRY THROUGH MUCH OF THE NGT. THIS WL CREATE A VERY CHALLENGING AND PROBLEMATIC TEMP FCST WITH LARGE TEMP GRADIENTS LIKELY TO CONTINUE ACROSS THE N AND NW TIER OF COUNTIES FROM JENKINS COUNTY NE TO BERKELEY COUNTY. HAVE MADE SOME MODIFICATIONS TO OUR TEMP GRIDS AND TXT FCSTS TO BETTER DEPICT THE FNTL PSN AND EXPECTED SHORT TERM TRENDS THROUGH SUNRISE. WL GO WITH LOWS RANGING FROM THE UPR 40S ACROSS THE EXTREME W AND NW WITH UPR 50S/LWR 60S ALONG THE COAST. PCPN IS FINALLY BEGINNING TO WORK ITS WAY INTO THE WRN ZONES THIS EVNG. RADAR COMPOSITES SHOWS AN EXPANSIVE BAND OF LGT TO MODERATE RAIN EXTENDING FROM SRN LA INTO THE MID-ATLC. THE AREA OF ENHANCED RNFL NOTED ACROSS E-CNTRL GA INTO THE MIDLANDS IS ASSOC WITH AN AREA OF STRONG ISENTROPIC UPGLIDE AND ALIGNS PERFECTLY WITH THE RUC 290-295K ADIABATIC OMEGA FIELDS. THE RUC SHOWS THIS AREA OF ENHANCED LIFT SHIFTING E ACROSS MUCH OF THE CWFA AFT MIDNGT AS A 45-50 KT LLJ FEEDS IN FROM THE S. WL GO WITH 100 POPS FOR MOST OF THE CWFA TNGT...EXCEPT ALONG THE N GA COAST AND THE I-95 CORRIDOR S OF SAVANNAH WHERE SLGTLY LWR POPS WL BE MAINTAINED AS THE BULK OF THE HEAVIEST PCPN WL LIKELY HOLD OFF UNTIL CLOSER TO SUNRISE IN THOSE AREAS. HPC QPF AMOUNTS 1 TO 1.5 INCHES LOOKS ON TRACK FOR TNGT THROUGH MON. && .MARINE...WNDS ARE BEGINNING TO PICK UP ACROSS THE WTRS THIS EVNG PER BUOY AND PILOT BOAT REPORTS...PARTICULARLY ACROSS THE GA OFFSHORE WTRS. BEST CHANCES FOR SCA CONDITIONS WL BE ACROSS THE GA OFFSHORE WTRS AND THE NEAR SHORE WTRS N OF EDISTO BEACH WHERE FLAGS ARE ALREADY OUT. IT STILL LOOKS LIKE THE NEAR SHORE WTRS FROM EDISTO TO THE ALTAMAHA WL REMAIN BELOW SCA CRITERIA AS THIS AREA WL BE FARTHEST AWAY FROM THE STRONGEST LLJ. ONLY MINOR INITIALIZATION TWEAKS ARE NECESSARY FOR THE EVNG FCST PKG. THE CHARLESTON HARBOR PILOT BOAT REPORTED SE WINDS NEAR 18 KT AND SEAS OF 3 FT ABT 15 NM E OF THE HARBOR ENTRANCE ABT 45 MIN AGO. && .AVIATION /00Z-24Z/...CONDITIONS WL STEADILY DETERIORATE AT BOTH TERMINALS TNGT AS A LARGE BAND OF PCPN SLOWLY SHIFTS E TO THE COAST. IFR CONDITIONS APPEAR LIKELY CLOSER TO SUNRISE AS BOTH VSBYS AND CIGS LWR WITH THE ONSET OF PCPN. CONDITIONS ARE EXPECTED TO SLOWLY DIMINISH BY MON AFTN AS DRIER AIR BEGINS TO FILTER IN FROM THE NW. THE RISK FOR LLWS WL REMAIN VERY HIGH THROUGH MID-MRNG MON AS A STRONG LLJ WL REMAINS ANCHORED ACROSS THE RGN. KCLX VWP ALREADY SHOWS 1500 FT WNDS AROUND 40 KT AND THESE CONDITIONS WL CONTINUE. ALTHOUGH SFC WNDS WL LIKELY INCR AFT MIDNGT...SPEED AND DIRECTIONAL DIFFERENCES FROM THE SFC TO AT LEAST 1500 FT WL BE ENOUGH THAT AT LEAST 34-37 KT OF SHEAR CAN BE EXPECTED. && .CHS WATCHES/WARNINGS/ADVISORIES... GA...NONE. SC...NONE. MARINE...SMALL CRAFT ADVISORY FOR AMZ350-374. && $$ ST ga AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NORTHERN INDIANA 1255 AM EST MON JAN 22 2007 .AVIATION... AREA OF LOW PRESSURE OVER NE INDIANA/NW OH WILL MOVE EAST TO THE LWR GRTLKS BY MORNING. SLIGHT INCREASE IN WINDS BEHIND THE LOW WAS RESULTING IN RISING VSBYS/CIGS. EXPECT THIS TREND TO CONTINUE AT TERMINALS OVERNIGHT BUT ABUNDANT LOW LEVEL MOISTURE SHOULD KEEP CIGS FROM RISING ABOVE MVFR. UPPER LEVEL TROF OVER IA WILL MOVE ACROSS NRN INDIANA DURING THE DAY MONDAY AND AIDED BY LOW LEVEL FETCH OFF LM SHOULD RESULT IN A PERIOD OF LIGHT SNOW SHOWERS. && .SHORT TERM... TONIGHT AND MONDAY. WILL LEAN MORE TOWARD THE 12Z NAM-WRF AND LATEST RUC40 FOR THE SHORT TERM FCST AS THEY SEEM TO BE CAPTURING CURRENT SYNOPTIC FEATURES THE BEST. UPR LVL S/WV OVER FAR ERN IOWA THIS AFTN WILL SHEAR AS IT MOVES EAST ACRS SRN LOWER MICHIGAN/FAR NRN INDIANA THIS EVENING. THIS FEATURE WILL BE ASSOCIATED WITH A WEAK SFC LOW THAT WILL ALSO TRAVERSE ACRS NRN INDIANA BETWEEN 00Z AND 06Z. THE UPR LVL LIFT FROM THE S/WV...ALONG WITH WEAK FORCING FROM THE SFC TO 850 MB...WILL BE ENOUGH TO WARRANT LIKELY POPS ACRS THE NRN THIRD OF THE FCST AREA THROUGH EARLY MORNING. THIS SCENARIO SEEMS PLAUSIBLE GIVEN RADAR RETURNS ACRS NRN ILLINOIS THIS AFTN. FARTHER SOUTH...ONLY A CHC OF PCPN IS EXPECTED. WITH DEEPER MOISTURE MOVING ACRS THE MAJORITY OF THE FCST AREA OVERNIGHT...FREEZING PCPN IN THE FORM OF DRIZZLE SHOULD BECOME LESS LIKELY AS MORE ICE NUCLEATION CAN BE EXPECTED AS THE ATMOSPHERE BECOMES SATURATED AROUND -10 C AND COLDER. THE FAR SOUTH...HOWEVER...WILL BE ON THE BORDER OF THIS DEEPER MOISTURE...SO WILL KEEP A THREAT OF FREEZING DRIZZLE IN THIS LOCATION. OTHERWISE...CHANCE OF LIGHT SNOW/FREEZING DRIZZLE SOUTH TO LIKELY LIGHT SNOW NORTH CAN BE EXPECTED THROUGH EARLY MORNING. ONCE THE S/WV GOES BY AND WEAK SFC LOW MOVES OFF TO THE EAST...CHC/S OF PCPN WILL DIMINISH TO 30 PERCENT. ANY ADDITIONAL SNOWFALL AMOUNTS WILL BE LESS THAN AN INCH. OVERNIGHT LOWS WILL BE TRICKY GIVEN THAT TEMPS WILL CONTINUE TO SLOWLY CLIMB AHEAD OF WEAK SFC LOW THROUGH THIS AFTN BEFORE LEVELING OFF. ONCE THE LOW LVL WIND FLOW SHIFTS TO THE NORTH/NORTHWEST LATER TONIGHT...TEMPS WILL BEGIN TO FALL OFF. WILL GENERALLY FORECAST LOWER AND MID 20S NORTH AND WEST WITH UPPER 20S FAR SOUTHEAST. ON MONDAY...A SHEAR AXIS OF VORTICITY WILL PASS ACRS THE FCST AREA. ALSO...850 MB TEMPS DROP TO -10 C TO -11 C...PRODUCING DELTA T/S IN THE 14 C TO 15 C RANGE...ENOUGH TO DEVELOP SOME LAKE EFFECT SNOW SHOWERS. THE MEAN LOW LVL FLOW WILL START OUT AROUND 340...THEN IT WILL SHIFT TO ABOUT A 290 DIRECTION BY LATE IN THE DAY. WILL PLACE 50 POPS ACRS BERRIEN...LAPORTE AND ST. JOE INDIANA COUNTIES AS THEY WILL HAVE THE HIGHEST THREAT FOR MEASURABLE SNOW. SNOW CHC/S WILL DECREASE TO 40 PERCENT JUST OUTSIDE THIS REGION...THEN TO 30 PERCENT WELL AWAY FROM THE LAKE. HIGHS ON MONDAY WILL RANGE FROM THE UPPER 20S NORTH TO THE LOWER 30S SOUTH...CLOSE TO MAV MOS GUIDANCE...WHICH IS REASONABLE AND ACCEPTED. && .LONG TERM... EXTENDED TO BEGIN WITH SERIES OF DISTURBANCES IN PREDOMINATELY NW FLOW REGIME. ONE MORE SHORT WAVE COMING ACROSS MONDAY NIGHT KEEPING CHANCE FOR LIGHT SNOW OVER THE CWA. A BRIEF BREAK IN BETWEEN DISTURBANCES ON TUESDAY AS WEAK SFC RIDING NUDGES INTO THE AREA. MOISTURE BEGINS SPILLING INTO LWR MICHIGAN TUE NITE BUT FOR NOW BOTH GFS AND NAM CONSISTENT WITH KEEPING BEST FOCUS FOR PRECIP JUST NORTH OF OUR AREA TUE NIGHT SO WILL KEEP WITH GOING FORECAST IN HOLDING OFF ON POPS UNTIL WEDNESDAY. BEHIND THIS DISTURBANCE...PATTERN AMPLIFIES SIGNIFICANTLY MID WEEK AS WEST COAST RIDGE CONTINUES TO BUILD OVER TOP OF CLOSED LOW THAT DROPS DOWN INTO NORTHERN MEXICO. RIDGE AXIS ALSO SHIFTING SLIGHTLY EAST INTO ROCKIES RESULTING IN STRONG N/NW FLOW OVER OUR AREA BRINGING FAVORABLE LAKE EFFECT CONDITIONS BEGINNING WEDNESDAY NIGHT. MEDIUM RANGE MODELS THEN BEGIN TO DIFFER ON TIMING END OF THE WEEK. SFC RIDGING GRADUALLY BUILDS UP FROM THE TN VALLEY AND SHOULD BRING AN END TO ANY LAKE EFFECT SHSN BY FRIDAY. NEXT SYSTEM TO WORK ITS WAY ACROSS SOUTHERN CANADA BY THE WEEKEND AND BRING A COLD FRONT AND ANOTHER CHANCE FOR SNOW INTO THE AREA. ECMWF/GEM/GFS ALL OFFER DIFFERENT TIMING WITH THIS SYSTEM BUT DOES SEEM PRUDENT TO INTRODUCE A CHANCE OF SNOW ON SATURDAY. MODELS STILL SUGGESTING ARCTIC AIR INTRUSION BEHIND THIS SYSTEM AND WITH SFC HIGH SETTLING INTO THE NORTHERN PLAINS SHOULD SEE A CONTINUED CYCLONIC FLOW AND LAKE EFFECT POTENTIAL INTO SUNDAY. TEMPS THROUGH THE PERIOD SHOULD REMAIN SEASONABLY COOL WITH THE POTENTIAL FOR GOING MORE DECIDEDLY BELOW NORMAL BY DAY 7. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...NONE. MI...NONE. OH...NONE. LM...NONE. && $$ AVIATION...TAYLOR SHORT TERM...HICKMAN LONG TERM....LOGSDON in AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE INDIANAPOLIS IN 1220 AM EST MON JAN 22 2007 .AVIATION...DISCUSSION FOR 220600Z TAF ISSUANCE. DISORGANIZED AREA OF WEAK SFC LOW PRESSURE NEAR MIE WL SHIFT E ACRS NRN OH OVERNGT. MODEL TIME SECS KEEP ATMS SATURATED THROUGH THE TAF PD AT AND BLO 850 MB. ALSO...INVERSION SEEN ON MODEL SOUNDINGS SHOULD KEEP IFR CONDS GOING UNTIL POSSIBLY TOMORROW AFT WHEN THE SC DECK COULD COME UP BARELY INTO THE MVFR RANGE. MEANWHILE...COULD STILL SEE SOME DRZL/FRZG DRZL AROUND TNGT...BUT DON/T EXPECT ANYTHING SIGNIFICANT WITH LIFT LACKING. && .UPDATE... TEMPERATURES ARE ABOVE FREEZING ACROSS THE FORECAST AREA /FA/ AT 03Z. UPPER WAVE IS EXITING TO THE E TAKING BULK OF LIFT WITH IT. WEAK SURFACE LOW WAS JUST MOVING E OF THE FA AS WELL. NOT A LOT OF COLD AIR ADVECTION BEHIND THIS LOW...AND LATEST NAM REFLECTS THIS WITH WARMER TEMPERATURES. RUC IS A LITTLE COOLER BUT STILL REFLECTS THE TREND. FORECAST SOUNDINGS SHOW THAT DRIZZLE WILL CONTINUE TO BE THE DOMINANT PRECIP TYPE AS TEMPS ARE NOT FAVORABLE FOR ICE CRYSTAL FORMATION. WITH THE EXPECTED WARMER TEMPERATURES...HAVE DECIDED TO DROP ADVISORY ACROSS THE FAR SOUTHERN TIER. WILL BE BORDERLINE BY MORNING...BUT FEEL THAT PROBLEMS WILL NOT BE WIDESPREAD. ACROSS THE BMG AND BAK AREAS HAVE DELAYED TIMING AS TEMPS WILL NOT FALL TO BELOW FREEZING UNTIL LATER TONIGHT. LEFT THE REMAINDER OF THE ADVRY ALONE. && .PREV DISCUSSION... SHORT TERM FORECAST FOCUS IS ON A VERY LIGHT WINTER WX EVENT OVERNIGHT THAT COULD HAVE SOME IMPACT ON TRAVEL IN THE AREA. CURRENT WEATHER MAP SHOWS SNOW HAS EXITED THE AREA AND LEFT BEHIND FREEZING DRIZZLE. H5 LOW HAS TRACKED WELL TO OUR NORTHWEST AND BROUGHT IN SOME WARMING AND DRYING IN THE MID LEVELS...LEAVING MOISTURE TRAPPED UNDERNEATH AND CAUSING THE DRIZZLE. FOR TONIGHT EXPECTING TEMPERATURES TO REMAIN NEARLY STEADY FOR SEVERAL HOURS IN THE LOWER 30S. WARMER AIR HAS BEEN SNEAKING NORTHWARD ALL DAY LONG. WITH THE LOW REMAINING TO OUR NORTHWEST...NOT EXPECTING A SHARP COOL DOWN EARLY ON. A SFC TROUGH WILL SWING SOUTH LATER TONIGHT AND DROP TEMPS OFF...ESPECIALLY AFTER 06Z WHEN A MORE NORTHERLY WIND DEVELOPS AND SENDS TEMPS INTO THE MIDDLE AND UPPER 20S. AFTER MUCH DELIBERATION HAVE DECIDED TO GO WITH A WINTER WX ADVISORY AFTER 06Z TONIGHT. WHILE THE MODELS DO NOT SHOW MUCH QPF...THE CURRENTLY OCCURRING DRIZZLE IS EXPECTED TO CONTINUE ALL NIGHT. THE OVERALL SOUNDING CHANGES LITTLE WITH THE LOW LEVEL TRAPPED MOISTURE AND THE SUBTLE LIFT GENERATED BY THE H5 LOW AND THE WEAK SFC TROUGH. AS TEMPS FALL BELOW FREEZING AFTER 06Z...THE DRIZZLE IS EXPECTED TO BEGIN TO STICK TO SURFACES ESPECIALLY UNTREATED ONES. WITH THE MONDAY MORNING RUSH...THIS COULD BE A MINOR EVENT WITH POTENTIALLY BIG IMPACTS. AFTER 15Z ON MONDAY...PROFILE CHANGES ENOUGH TO FAVOR SOME FLURRIES RATHER THAN DRIZZLE. WILL ISSUE ADVISORY THRU 15Z MONDAY SPECIFICALLY FOR AN EXTENDED PERIOD OF FREEZING DRIZZLE OVERNIGHT. TEMPS WILL WARM TO MIDDLE 30S ON MONDAY AFTER PRECIP ENDS WITH HIGH PRESSURE BUILDING IN. TEMPS EXPECTED TO REMAIN SEASONABLY COLD THROUGH MID WEEK. H8 TEMPS WILL REMAIN -4 TO -8C. SFC HIGH WILL SLOWLY BUILD IN ACROSS THE SOUTHERN PLAINS. SOME WEAK WAVES FROM TIME TO TIME BUT NOTHING OVERLY IMPRESSIVE SO SNOW FOR THE EARLY PORTION OF THE WEEK SHOULD BE CONFINED TO JUST FLURRIES. A MORE SIGNIFICANT WAVE BY OVERNIGHT TUESDAY AND IT SHOULD REMAIN WELL NORTH THROUGH 12Z WED. LONG TERM.../WEDNESDAY THROUGH SUNDAY/ MAIN WEATHER FACTOR IN THE EXTENDED FORECAST IS THE CHANCE OF SNOW ON WEDNESDAY AND THURSDAY. GFS/NAM IN DECENT AGREEMENT. A COLD FRONT WILL BE MOVING THROUGH INDIANA MID WEEK. THIS WILL GIVE A CHANCE OF SNOW AS IT MOVES THROUGH. HIGH PRESSURE WILL THEN BUILD INTO THE AREA FOR THE REMAINDER OF THE EXTENDED PERIOD. MUCH COLDER AIR WILL MOVE INTO INDIANA OVER THE WEEKEND. LOWS WILL DROP INTO THE TEENS. ON SUNDAY INDIANA RECEIVED 1 TO 2 INCHES OF SNOW SOUTH AND 2 TO 5 INCHES CENTRAL AND NORTH. ONLY A MINOR AMOUNT OF MELTING OF THIS BEFORE THE EXTENDED PERIOD. DUE TO THIS SNOW COVER HAVE LOWERED THE TEMPERATURES ALL PERIODS SOME ESPECIALLY THE LOWS. && .IND WATCHES/WARNINGS/ADVISORIES... WINTER WEATHER ADVISORY UNTIL 11 AM EST MONDAY FOR INZ021-028>031-035>049-051>057. WINTER WEATHER ADVISORY FROM 4 AM TO 11 AM EST MONDAY FOR INZ060>065. && $$ UPDATE...CS SHORT TERM...JOHNSON LONG TERM...SH AVIATION...MK in AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE INDIANAPOLIS IN 1032 PM EST SUN JAN 21 2007 .UPDATE... TEMPERATURES ARE ABOVE FREEZING ACROSS THE FORECAST AREA /FA/ AT 03Z. UPPER WAVE IS EXITING TO THE E TAKING BULK OF LIFT WITH IT. WEAK SURFACE LOW WAS JUST MOVING E OF THE FA AS WELL. NOT A LOT OF COLD AIR ADVECTION BEHIND THIS LOW...AND LATEST NAM REFLECTS THIS WITH WARMER TEMPERATURES. RUC IS A LITTLE COOLER BUT STILL REFLECTS THE TREND. FORECAST SOUNDINGS SHOW THAT DRIZZLE WILL CONTINUE TO BE THE DOMINANT PRECIP TYPE AS TEMPS ARE NOT FAVORABLE FOR ICE CRYSTAL FORMATION. WITH THE EXPECTED WARMER TEMPERATURES...HAVE DECIDED TO DROP ADVISORY ACROSS THE FAR SOUTHERN TIER. WILL BE BORDERLINE BY MORNING...BUT FEEL THAT PROBLEMS WILL NOT BE WIDESPREAD. ACROSS THE BMG AND BAK AREAS HAVE DELAYED TIMING AS TEMPS WILL NOT FALL TO BELOW FREEZING UNTIL LATER TONIGHT. LEFT THE REMAINDER OF THE ADVRY ALONE. && .AVIATION...DISCUSSION FOR 220000Z TAF ISSUANCE. MODEL TIME SECS/LOW LVL RH PROGS/MOS AND SFC OBS FAVOR KEEPING LIFR CONDS IN THROUGH MUCH OF THE NGT. CIGS SHOULD IMPV AFTER DAYBREAK PER MOS AND UPSTREAM CIGS ACRS MO. MEANWHILE...THE SIG PRECIP IS LONG GONE AS DRY SLOT CONTS TO MOVE IN ACRS THE TAF SITES. COULD STILL BE SOME LGT SN OR DRZL/FRZG DRZL BEFORE 02Z PER RADAR TRENDS/SFC OBS. SFC LOW ACRS NRN IL SEEMS A BIT BEHIND THE 6 HOUR MODEL PROGS...SO DELAYED THE WIND SHIFT A FEW HOURS UNTIL LATE THIS EVE. && .PREV DISCUSSION... SHORT TERM FORECAST FOCUS IS ON A VERY LIGHT WINTER WX EVENT OVERNIGHT THAT COULD HAVE SOME IMPACT ON TRAVEL IN THE AREA. CURRENT WEATHER MAP SHOWS SNOW HAS EXITED THE AREA AND LEFT BEHIND FREEZING DRIZZLE. H5 LOW HAS TRACKED WELL TO OUR NORTHWEST AND BROUGHT IN SOME WARMING AND DRYING IN THE MID LEVELS...LEAVING MOISTURE TRAPPED UNDERNEATH AND CAUSING THE DRIZZLE. FOR TONIGHT EXPECTING TEMPERATURES TO REMAIN NEARLY STEADY FOR SEVERAL HOURS IN THE LOWER 30S. WARMER AIR HAS BEEN SNEAKING NORTHWARD ALL DAY LONG. WITH THE LOW REMAINING TO OUR NORTHWEST...NOT EXPECTING A SHARP COOL DOWN EARLY ON. A SFC TROUGH WILL SWING SOUTH LATER TONIGHT AND DROP TEMPS OFF...ESPECIALLY AFTER 06Z WHEN A MORE NORTHERLY WIND DEVELOPS AND SENDS TEMPS INTO THE MIDDLE AND UPPER 20S. AFTER MUCH DELIBERATION HAVE DECIDED TO GO WITH A WINTER WX ADVISORY AFTER 06Z TONIGHT. WHILE THE MODELS DO NOT SHOW MUCH QPF...THE CURRENTLY OCCURRING DRIZZLE IS EXPECTED TO CONTINUE ALL NIGHT. THE OVERALL SOUNDING CHANGES LITTLE WITH THE LOW LEVEL TRAPPED MOISTURE AND THE SUBTLE LIFT GENERATED BY THE H5 LOW AND THE WEAK SFC TROUGH. AS TEMPS FALL BELOW FREEZING AFTER 06Z...THE DRIZZLE IS EXPECTED TO BEGIN TO STICK TO SURFACES ESPECIALLY UNTREATED ONES. WITH THE MONDAY MORNING RUSH...THIS COULD BE A MINOR EVENT WITH POTENTIALLY BIG IMPACTS. AFTER 15Z ON MONDAY...PROFILE CHANGES ENOUGH TO FAVOR SOME FLURRIES RATHER THAN DRIZZLE. WILL ISSUE ADVISORY THRU 15Z MONDAY SPECIFICALLY FOR AN EXTENDED PERIOD OF FREEZING DRIZZLE OVERNIGHT. TEMPS WILL WARM TO MIDDLE 30S ON MONDAY AFTER PRECIP ENDS WITH HIGH PRESSURE BUILDING IN. TEMPS EXPECTED TO REMAIN SEASONABLY COLD THROUGH MID WEEK. H8 TEMPS WILL REMAIN -4 TO -8C. SFC HIGH WILL SLOWLY BUILD IN ACROSS THE SOUTHERN PLAINS. SOME WEAK WAVES FROM TIME TO TIME BUT NOTHING OVERLY IMPRESSIVE SO SNOW FOR THE EARLY PORTION OF THE WEEK SHOULD BE CONFINED TO JUST FLURRIES. A MORE SIGNIFICANT WAVE BY OVERNIGHT TUESDAY AND IT SHOULD REMAIN WELL NORTH THROUGH 12Z WED. LONG TERM.../WEDNESDAY THROUGH SUNDAY/ MAIN WEATHER FACTOR IN THE EXTENDED FORECAST IS THE CHANCE OF SNOW ON WEDNESDAY AND THURSDAY. GFS/NAM IN DECENT AGREEMENT. A COLD FRONT WILL BE MOVING THROUGH INDIANA MID WEEK. THIS WILL GIVE A CHANCE OF SNOW AS IT MOVES THROUGH. HIGH PRESSURE WILL THEN BUILD INTO THE AREA FOR THE REMAINDER OF THE EXTENDED PERIOD. MUCH COLDER AIR WILL MOVE INTO INDIANA OVER THE WEEKEND. LOWS WILL DROP INTO THE TEENS. ON SUNDAY INDIANA RECEIVED 1 TO 2 INCHES OF SNOW SOUTH AND 2 TO 5 INCHES CENTRAL AND NORTH. ONLY A MINOR AMOUNT OF MELTING OF THIS BEFORE THE EXTENDED PERIOD. DUE TO THIS SNOW COVER HAVE LOWERED THE TEMPERATURES ALL PERIODS SOME ESPECIALLY THE LOWS. && .IND WATCHES/WARNINGS/ADVISORIES... WINTER WEATHER ADVISORY UNTIL 11 AM EST MONDAY FOR INZ021-028>031-035>049-051>057. WINTER WEATHER ADVISORY FROM 4 AM TO 11 AM EST MONDAY FOR INZ060>065. && $$ UPDATE...CS SHORT TERM...JOHNSON LONG TERM...SH AVIATION...MK in AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NORTHERN INDIANA 641 PM EST SUN JAN 21 2007 .AVIATION... SHORT WAVE AND WEAK SURFACE LOW MOVING THROUGH THE AREA HELPING GENERATE AN AREA OF LIGHT SNOW. THIS SHOULD SPREAD ACROSS INDIANA INTO KFWA NEXT HOUR. VISIBILITIES DOWN TO NEAR 1SM WITH -SN AND BR. JUST SOUTH OF THIS SNOW AREA...LIGHT WINDS HAVE LED TO DENSE FOG. WILL HAVE TO WATCH HOW VIS REACTS ONCE LIGHT SNOW ENDS LATER THIS EVENING. LOW LEVEL MOISTURE REMAINS DEEP AND OVER THE AREA THROUGH TOMORROW ALONG WITH SOME TRAJECTORIES OFF THE LAKE. HAVE KEPT THE LOW CIGS IN PLACE THROUGH TOMORROW. ANOTHER SHORT WAVE IS ALSO EXPECTED TOMORROW WHICH MAY HELP GENERATE ANOTHER ROUND OF SNOW SHOWERS COUPLED WITH FLOW OFF THE LAKE. TRAJECTORIES WOULD FAVOR THIS INTO KFWA AS WELL. && .SHORT TERM... TONIGHT AND MONDAY. WILL LEAN MORE TOWARD THE 12Z NAM-WRF AND LATEST RUC40 FOR THE SHORT TERM FCST AS THEY SEEM TO BE CAPTURING CURRENT SYNOPTIC FEATURES THE BEST. UPR LVL S/WV OVER FAR ERN IOWA THIS AFTN WILL SHEAR AS IT MOVES EAST ACRS SRN LOWER MICHIGAN/FAR NRN INDIANA THIS EVENING. THIS FEATURE WILL BE ASSOCIATED WITH A WEAK SFC LOW THAT WILL ALSO TRAVERSE ACRS NRN INDIANA BETWEEN 00Z AND 06Z. THE UPR LVL LIFT FROM THE S/WV...ALONG WITH WEAK FORCING FROM THE SFC TO 850 MB...WILL BE ENOUGH TO WARRANT LIKELY POPS ACRS THE NRN THIRD OF THE FCST AREA THROUGH EARLY MORNING. THIS SCENARIO SEEMS PLAUSIBLE GIVEN RADAR RETURNS ACRS NRN ILLINOIS THIS AFTN. FARTHER SOUTH...ONLY A CHC OF PCPN IS EXPECTED. WITH DEEPER MOISTURE MOVING ACRS THE MAJORITY OF THE FCST AREA OVERNIGHT...FREEZING PCPN IN THE FORM OF DRIZZLE SHOULD BECOME LESS LIKELY AS MORE ICE NUCLEATION CAN BE EXPECTED AS THE ATMOSPHERE BECOMES SATURATED AROUND -10 C AND COLDER. THE FAR SOUTH...HOWEVER...WILL BE ON THE BORDER OF THIS DEEPER MOISTURE...SO WILL KEEP A THREAT OF FREEZING DRIZZLE IN THIS LOCATION. OTHERWISE...CHANCE OF LIGHT SNOW/FREEZING DRIZZLE SOUTH TO LIKELY LIGHT SNOW NORTH CAN BE EXPECTED THROUGH EARLY MORNING. ONCE THE S/WV GOES BY AND WEAK SFC LOW MOVES OFF TO THE EAST...CHC/S OF PCPN WILL DIMINISH TO 30 PERCENT. ANY ADDITIONAL SNOWFALL AMOUNTS WILL BE LESS THAN AN INCH. OVERNIGHT LOWS WILL BE TRICKY GIVEN THAT TEMPS WILL CONTINUE TO SLOWLY CLIMB AHEAD OF WEAK SFC LOW THROUGH THIS AFTN BEFORE LEVELING OFF. ONCE THE LOW LVL WIND FLOW SHIFTS TO THE NORTH/NORTHWEST LATER TONIGHT...TEMPS WILL BEGIN TO FALL OFF. WILL GENERALLY FORECAST LOWER AND MID 20S NORTH AND WEST WITH UPPER 20S FAR SOUTHEAST. ON MONDAY...A SHEAR AXIS OF VORTICITY WILL PASS ACRS THE FCST AREA. ALSO...850 MB TEMPS DROP TO -10 C TO -11 C...PRODUCING DELTA T/S IN THE 14 C TO 15 C RANGE...ENOUGH TO DEVELOP SOME LAKE EFFECT SNOW SHOWERS. THE MEAN LOW LVL FLOW WILL START OUT AROUND 340...THEN IT WILL SHIFT TO ABOUT A 290 DIRECTION BY LATE IN THE DAY. WILL PLACE 50 POPS ACRS BERRIEN...LAPORTE AND ST. JOE INDIANA COUNTIES AS THEY WILL HAVE THE HIGHEST THREAT FOR MEASURABLE SNOW. SNOW CHC/S WILL DECREASE TO 40 PERCENT JUST OUTSIDE THIS REGION...THEN TO 30 PERCENT WELL AWAY FROM THE LAKE. HIGHS ON MONDAY WILL RANGE FROM THE UPPER 20S NORTH TO THE LOWER 30S SOUTH...CLOSE TO MAV MOS GUIDANCE...WHICH IS REASONABLE AND ACCEPTED. && .LONG TERM... EXTENDED TO BEGIN WITH SERIES OF DISTURBANCES IN PREDOMINATELY NW FLOW REGIME. ONE MORE SHORT WAVE COMING ACROSS MONDAY NIGHT KEEPING CHANCE FOR LIGHT SNOW OVER THE CWA. A BRIEF BREAK IN BETWEEN DISTURBANCES ON TUESDAY AS WEAK SFC RIDING NUDGES INTO THE AREA. MOISTURE BEGINS SPILLING INTO LWR MICHIGAN TUE NITE BUT FOR NOW BOTH GFS AND NAM CONSISTENT WITH KEEPING BEST FOCUS FOR PRECIP JUST NORTH OF OUR AREA TUE NIGHT SO WILL KEEP WITH GOING FORECAST IN HOLDING OFF ON POPS UNTIL WEDNESDAY. BEHIND THIS DISTURBANCE...PATTERN AMPLIFIES SIGNIFICANTLY MID WEEK AS WEST COAST RIDGE CONTINUES TO BUILD OVER TOP OF CLOSED LOW THAT DROPS DOWN INTO NORTHERN MEXICO. RIDGE AXIS ALSO SHIFTING SLIGHTLY EAST INTO ROCKIES RESULTING IN STRONG N/NW FLOW OVER OUR AREA BRINGING FAVORABLE LAKE EFFECT CONDITIONS BEGINNING WEDNESDAY NIGHT. MEDIUM RANGE MODELS THEN BEGIN TO DIFFER ON TIMING END OF THE WEEK. SFC RIDGING GRADUALLY BUILDS UP FROM THE TN VALLEY AND SHOULD BRING AN END TO ANY LAKE EFFECT SHSN BY FRIDAY. NEXT SYSTEM TO WORK ITS WAY ACROSS SOUTHERN CANADA BY THE WEEKEND AND BRING A COLD FRONT AND ANOTHER CHANCE FOR SNOW INTO THE AREA. ECMWF/GEM/GFS ALL OFFER DIFFERENT TIMING WITH THIS SYSTEM BUT DOES SEEM PRUDENT TO INTRODUCE A CHANCE OF SNOW ON SATURDAY. MODELS STILL SUGGESTING ARCTIC AIR INTRUSION BEHIND THIS SYSTEM AND WITH SFC HIGH SETTLING INTO THE NORTHERN PLAINS SHOULD SEE A CONTINUED CYCLONIC FLOW AND LAKE EFFECT POTENTIAL INTO SUNDAY. TEMPS THROUGH THE PERIOD SHOULD REMAIN SEASONABLY COOL WITH THE POTENTIAL FOR GOING MORE DECIDEDLY BELOW NORMAL BY DAY 7. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...NONE. MI...NONE. OH...NONE. LM...NONE. && $$ AVIATION...LASHLEY SHORT TERM...HICKMAN LONG TERM....LOGSDON in AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GOODLAND KS 230 AM MST TUE JAN 23 2007 .DISCUSSION...FORECAST PROBLEM WILL BE TEMPERATURES. SATELLITE SHOWING AMPLIFIED AND COMPLICATED FLOW FROM THE PACIFIC INTO NORTH AMERICA. BROAD TROUGH OVER THE EASTERN PACIFIC HAS NUMEROUS CIRCULATIONS WITHIN IT. VERY HARD TO PICK OUT DETAILS THERE. RIDGE HAS BUILT ALONG THE WEST COAST. FAIRLY STRONG SYSTEM IS MOVING THROUGH THE NORTH CENTRAL PORTION OF THE COUNTRY. AIR MASS HAS WARMED CONSIDERABLY OVER THE LAST 24 HOURS. HOWEVER...SUBSTANTIAL SNOWPACK STILL COVERS THE AREA AND WILL FOR A WHILE. AT JET LEVEL...WITH JET SEGMENT OVER THE TOP OF THE WESTERN RIDGE... THE NAM WAS DOING BETTER THAN THE GFS. WITH POWERFUL SOUTHERN STREAM JET...MODELS WERE UNDERDOING THE STRENGTH. AT MID LEVELS...BASED ON SATELLITE...THE GFS AND UKMET LOOK TO BE CAPTURING THE COMPLICATED NATURE OF THE EASTERN PACIFIC TROUGH THE BEST WITH EACH DOING BETTER IN DIFFERENT PLACES. HOWEVER...THE NAM AND RUC LOOK TO BE CAPTURING NORTH CENTRAL SHORTWAVE TROUGH THE BEST. MODELS WERE STILL TOO FAR SOUTH AND EAST WITH THE HEIGHT FIELD BUT NOT AS BAD AS YESTERDAY. AT LOW LEVELS...FOR TEMPERATURES...MODELS WERE A LITTLE WARM FROM THE PANHANDLE AREA INTO CENTRAL NEBRASKA. MODELS WERE TOO COOL OVER WESTERN SOUTH DAKOTA...AND A LITTLE TOO WARM OVER EASTERN MONTANA. OVERALL THE GFS WAS THE CLOSEST OF THE BUNCH. MODELS WERE NOT TOO FAR APART ON THE WINDS/PRESSURES WITH THE NAM A LITTLE BETTER. THIS WAS ESPECIALLY TRUE WITH THE BOUNDARY/WINDS THAT ARE COMING IN AT THIS TIME. ALSO THE GFS LOOKS TO OVERDEVELOPED WITH TIME WITH THE LEE TROUGH BY THURSDAY. BASE THIS ON LIGHT WIND FIELD ALOFT WITH NO SIGNIFICANT CROSS MOUNTAIN COMPONENT. AS YESTERDAY...A BLENDED MODEL APPROACH LOOKS TO BE IN ORDER. BELIEVE BECAUSE IT IS DOING A LITTLE BETTER OVER THE PACIFIC...LIKE THE UKMET BETTER AT MID/UPPER LEVELS. THE ECMWF AND NAM ARE MORE SIMILAR TO THE UKMET. ALSO THE ECMWF HAS BEEN MORE CONSISTENT WITH THE PATTERN...ESPECIALLY WHAT IS GOING TO HAPPEN WITH MEXICO LOW ONCE IT STARTS MOVING. HOWEVER...DUE TO THE COMPLEXITY OF THE FLOW OVER THE PACIFIC AND DIFFERENCES BETWEEN THE MODELS THERE... CONFIDENCE IS LOW IN ANY ONE SOLUTION RIGHT NOW. OTHERWISE...WILL GO WITH THE NAM/UKMET AT LOW LEVELS...ESPECIALLY ON THE TEMPERATURES. NAM 2 METER AND SOUNDINGS WORKED VERY WELL IN PREDICTING THE MAXES. TODAY/TONIGHT...CLOUD COVER WILL BE A FACTOR IN THE HIGH TEMPERATURES. THE NAM HAS A LITTLE LESS CLOUD COVER. HOWEVER...BASED ON STRONG SHORTWAVE AND CLOUD COVER SEEN ON SATELLITE...LOOKS LIKE WILL BE A DECENT AMOUNT OF CLOUD COVER IN THE MORNING WHICH WILL SLOW TEMPERATURE RISE. PER DISCUSSION WILL BE FOLLOWING 2 METER OR SOUNDINGS OF NAM...WHICHEVER IS COOLEST. IT WILL BE CLOSE...BUT KGLD MAY REACH 32 DEGREES FOR A MAX FOR THE FIRST TIME SINCE THE 10TH. WILL HAVE SOME CLOUD COVER...DUE TO ANOTHER SHORTWAVE TONIGHT...BUT WILL HAVE LIGHT WINDS. WILL GO NEAR TO SLIGHTLY BELOW GUIDANCE. WEDNESDAY/WEDNESDAY NIGHT...ABOVE MENTIONED SHORTWAVE TROUGH WILL BE FURTHER EAST THAN TODAYS...BUT WILL KEEP FLOW ALOFT STILL OUT OF THE NORTH. LOOKS TO BE MUCH LESS CLOUD COVER. AGAIN WILL GO WITH PERSISTANCE WITH THE TEMPERATURES...AND TWEEKED MAXES DOWN A TOUCH BASED ON THAT. LIGHT WINDS AND LESS CLOUD COVER WILL MAKE FOR COOLER MINS THIS NIGHT. THURSDAY/THURSDAY NIGHT...LIKE THE FURTHER WEST AND WEAKER RIDGE OF THE UKMET. ALSO WIND FIELD WILL BE LIGHT SO NOT A LOT OF ADVECTION GOING ON. BECAUSE OF THIS AND NAM SOUNDINGS STILL SHOWING A DECENT INVERSION...TWEEKED MAXES DOWN A FEW DEGREES FROM PREVIOUS FORECAST. STILL A LOT OF VARIABILITY IN THE MODEL SOLUTIONS IN EVOLUTION OF COMPLEX UPPER PATTERN. STILL LOOKS DRY AT THIS TIME WITH ANOTHER SHOT OF COLD AIR COMING. THEREFORE NO CHANGES PLANNED FOR DAY 4 AND AND BEYOND. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...NONE. NE...NONE. CO...NONE. && $$ BULLER ks AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GOODLAND KS 233 AM MST MON JAN 22 2007 .DISCUSSION...FORECAST PROBLEM WILL BE TEMPERATURES. SATELLITE SHOWING AN AMPLIFIED PATTERN FROM THE CENTRAL PACIFIC INTO NORTH AMERICA. VERY BROAD TROUGH OVER THEP PACIFIC WITH NUMEROUS SHORTWAVE TROUGHS AND STRONG JET ALONG THE SOUTHERN EDGE. AMPLIFYING RIDGE AND STRONG JET WINDS CAUSING ARIZONA TO DIG SOUTH. POSITIVELY TILTED TROUGH EXTENDS NORTHEAST OF THIS LOW. ANOTHER SHORTWAVE TROUGH IS MOVING IN FROM THE NORTHWEST TOWARD THE AREA. SUBSTANTIAL SNOWPACK OVER THE ENTIRE AREA. AT JET LEVEL...OVER THE CENTRAL PORTION OF THE COUNTRY...THEY DO NOT HAVE THE JET AXIS ON THE FRONT SIDE OF THE TROUGH FAR ENOUGH WITH THE GFS A LITTLE BETTER. HOWEVER...THE NAM HAS THE BETTER STRENGTH OF THE WINDS ON THE WEST SIDE OF THE UPPER TROUGH. AT MID LEVELS... ACCORDING TO SATELLITE IT INITIALLY LOOKED LIKE THE UKMET WAS CATCHING STRONG SYSTEM NEAR 150 WEST THE BEST. BUT BY 06Z THE GFS HAS LOCATION AND STRENGTH NEARLY ON THE MONEY. ALSO THE GFS HAS UPPER LOW NEAR THE ALUETIANS A LITTLE BETTER AS WELL. GFS ALONG WITH THE UKMET/RUC HAVE GOOD HANDLE ON SOUTHWEST UPPER LOW. BY THE HEIGHT ANALYSIS...MODELS HAVE THE RIDGE/HIGHER HEIGHTS FROM THE PACIFIC NORTHWEST INTO THE NORTH CENTRAL PORTION OF THE COUNTRY TOO HIGH. THE ECMWF DID SLIGHTLY BETTER THAN THE GFS/UKMET WITH THE WESTERN RIDGE. HOWEVER...OVER THE CENTRAL PORTION OF THE COUNTRY...THE UKMET/GFS WERE DOING BETTER WITH A SLIGHT EDGE TO THE UKMET. AT LOW LEVELS...MODELS INTIALIZED SUPRISINGLY WELL. HOWEVER...ONE SUSPECT AREA WAS NOTED. THE MODELS DID NOT HAVE THE COLD POOL FROM THE EASTERN HALF OF NEBRASKA INTO EASTERN SOUTH DAKOTA BROAD ENOUGH. THIS MAY HAVE HAD SOMETHING TO DO WITH THE KUNR OBSERVATION NOT BEING AVAILABLE. MODELS NOT TOO DIFFERENT ON SURFACE FIELD ALTHOUGH WOULD SAY NAM IS DOING SLIGHTLY BETTER. WILL PREFER THE UKMET/GFS ON MID/UPPER LEVELS WITH A SLIGHT EDGE TO THE UKMET...ESPECIALLY BECAUSE OF THE RIDGE AND DECENT SHORTWAVE TROUGH THAT COMES THROUGH THE CENTRAL PORTION OF THE COUNTRY ON TUESDAY. MODELS HAVE NOT CAUGHT ONTO SIGNIFICANCE OF SNOWFIELD... AND WILL USE MODEL/METHOD THAT KEEPS IT COOLEST OVER THE AREA. TODAY/TONIGHT...MAY HAVE A FEW CLOUDS AROUND BUT SHOULD BE A BIG DEAL. OF COURSE HAVE SUBSTANTIAL/THICK SNOWFIELD OVER THE AREA. WILL KEEP DOWNSLOPE WINDS ACROSS THE AREA DURING THE DAY. SO HOW MUCH WARMING WILL OCCUR. CURRENT OVERNIGHT TEMPERATURES ARE RUNNING COOLER THAN GUIDANCE SAYS WHAT IT IS. BASED ON COOLER NAM 2 METER AND SOUNDINGS WILL KEEP TEMPERATURES SIGNIFICANTLY UNDERNEATH GUIDANCE. DEPENDING ON HOW STRONG DOWNSLOPE WINDS STAY WILL DETERMINE MINS. SINCE MAXES LOOK TO BE WARM...WILL GO BELOW GUIDANCE HERE TOO. TUESDAY/TUESDAY NIGHT...SOUNDINGS INDICATE LITTLE TO NO CLOUD COVER. WINDS ARE MORE NORTHWEST AS STRONG SYSTEM DIGS INTO THE NORTHERN PLAINS. MODELS HAVE A LOT OF WARM AIR ADVECTION WHICH IS WAY OUT OF LINE WITH SNOW FIELD. NAM 2 METER AND SOUNDINGS...WHICH INDICATE LITTLE MIXING...HAVE TEMPERATURES IN THE MID TO UPPER 30S. THINK THIS MAY BE A LITTLE WARM SO LOWERED MAXES SLIGHTLY. IF 32 DEGREES OR HIGHER IS REACHED AT KGLD...IT WILL END A STREAK OF 11 STRAIGHT DAYS OF THE MAX BEING BELOW 32 DEGREES. NUMERICAL GUIDANCE OBSCENELY TOO WARM. WEDNESDAY/WEDNESDAT NIGHT...ABOVE MENTIONED SYSTEM LOOKS STRONG... AND BELIEVE MODELS ARE UNDERING DOING IT AND COOLING BEHIND IT. TWEEKED MAXES DOWN AND KEPT THEM WAY BELOW GUIDANCE BASED ON PERSISTANCE AND ABOVE MENTIONED 2 METER AND SOUNDINGS. THERE IS A LOT OF UNCERTAINTY WITH HOW TEMPERATURES WILL REACT WITH DOWNSLOPE WINDS AND SUNSHINE. ALSO MODELS ALL OVER THE PLACE WITH THE END OF THE WEEK SCENARIO. GFS BRINGS IN SOUTHERN LOW WHICH LOOKS OUT OF LINE. SO BASED ON THIS...NO CHANGES PLANNED FOR THROUGH DAY 5. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...NONE. NE...NONE. CO...NONE. && $$ BULLER ks AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LOUISVILLE KY 610 PM EST MON JAN 22 2007 .AVIATION... EXTENSIVE LOW STRATUS WILL CONTINUE OVERNIGHT THROUGH THE MORNING HOURS TUESDAY. PATCHY DRIZZLE OR FLURRIES MAY BRIEFLY REDUCE VISIBILITIES TO BELOW 5SM THIS EVENING. CEILINGS WILL REMAIN MVFR AND VARY BETWEEN 1 AND 1.5 THOUSAND FEET OVERNIGHT...BUT PERHAPS LOWER CLOSER TO ONE THOUSAND FEET AT LEX...DUE TO NORTHWEST FLOW AND HIGHER ELEVATION. SURFACE WINDS WILL REMAIN WEST NORTHWEST AT 5 TO 10 MPH OVERNIGHT..WITH 15-20 MPH WEST NORTHWEST WINDS AT 2000 FEET. DUE TO STRONG INVERSION AT 5000 FEET...LOW CLOUDS WILL BE SLOW TO ERODE...BUT MAY BECOME SCATTERED TUESDAY AFTERNOON. JSD .SHORT TERM (TONIGHT-TUESDAY)... EXTENSIVE LOW CLOUDS OVER THE ENTIRE OHIO VALLEY REGION TODAY. THIS COUPLED WITH WEAK COLD ADVECTION HAS LED TO STEADY OR SLOWLY FALLING TEMPS TODAY...IN THE MID-UPPER 30S MOST PLACES AS OF 19Z. SCT PRECIP ON RADAR...AND BASED ON SPOTTER REPORTS COUPLED WITH ACARS DATA... PTYPE IS A MIX OF -RA/-SN/-PL...BUT INTENSITIES ARE VERY LIGHT. EXPECT THIS TO CONTINUE FOR THE REMAINDER OF THE AFTN HOURS. FCST SOUNDINGS SHOW LOW LEVEL LAPSE RATES STEEPENING INTO THE EVENING HOURS. THIS ALONG WITH LIFT FROM PASSING UPPER TROF WILL HELP CONTINUE POTENTIAL FOR PRECIP THIS EVENING...WILL WORD AS SLIGHT CHANCE OF -SHRA/-SHSN...HOWEVER AIRMASS ABOVE 800MB (ICE CRYSTAL LEVELS) IS FCST TO REMAIN ON THE DRY SIDE...SO PRECIP AMTS SHOULD BE LIGHT AND WE MAY END UP SEEING MORE OF A PATCHY LIGHT DRIZZLE/FLURRY TYPE DEAL. WILL MENTION ISLTD SLICK SPOTS POSSIBLE IN THE HWO FOR TONIGHT AND EARLY TUESDAY MORNING. CHANCES FOR PRECIP SHOULD DIMINISH AFTER 6Z AS UPPER WAVE PASSES OFF TO THE EAST...BUT SKIES WILL REMAIN CLOUDY PER NAM/GFS FCST SOUNDINGS. BOTH SHOW CLOUD COVER DIMINISHING TUESDAY AS DRIER AIR ADVECTS IN FROM THE W/SW...WHICH IS OBSERVED IN VISIBLE SATELLITE OVER AR/OK ATTM. HOWEVER THAT MAY BE DELAYED DUE TO VERY STRONG INVERSION SEEN AROUND 850MB. OVERALL WILL TREND TOWARD PARTLY CLOUDY WORDING IN THE AFTN TUESDAY. REGARDING TEMPS...USED A 50/50 BLEND OF NAM/GFS TEMPS WHICH YIELDED MIDDLE 20S MOST LOCATIONS FOR LOWS TONIGHT...AND UPPER 30S/LOWER 40S FOR HIGHS TUESDAY. CS .LONG TERM (TUESDAY NIGHT-MONDAY)... TUES NIGHT-WED NIGHT... THIS PERIOD BEGINS WITH THE UPPER FLOW PATTERN MAINLY ZONAL/SLIGHTLY NW. AT THE SFC...LOW PRESSURE AND ASSOCIATED FRONT EXTEND FROM HUDSON BAY SW TO SRN GREAT LAKES. A SHORTWAVE EMBEDDED IN WNW FLOW ALOFT IS LOCATED ACROSS THE NRN PLAINS. AT THIS TIME...THINK THE SFC FRONT FROM THE GREAT LAKES MAY STAY TO OUR NE FOR THE MOST PART...AND ONLY BRING A SLIGHT WIND SHIFT TO THE AREA WED MORNING. HOWEVER TIME-HEIGHT CROSS SECTIONS ACROSS OUR NE FROM THE NAM AND GFS INDICATE DEEPER MOISTURE FROM 06-12Z...EXTENDING INTO THE -5 TO -15 DEGREE C RANGE. THINK THAT ONLY TRACE AMOUNTS OF PRECIP WOULD OCCUR (IN THE FORM OF FLURRIES) SO MAY INSERT THIS INTO THE GRIDS. THINK A BETTER CHANCE RESIDES WITH THE UPPER PLAINS` SHORTWAVE DIVING SEWD ACROSS THE CWA WED NIGHT. THIS MAY HELP SPARK A FEW LIGHT SHOWERS ACROSS THE AREA...WITH THE BEST CHANCE ACROSS THE NERN CWA. THINK SLT CHC SNOW SHOWERS SHOULD DO THE TRICK. ANY PRECIP WOULD BE LIGHT IN NATURE. THU-FRI... THIS PERIOD WILL BE MAINLY DRY AS UPPER TROUGH MOVES OFF TO THE NE AND SFC HIGH PRESSURE TRIES TO NOSE IN FROM THE WEST. STILL A NW FLOW ALOFT WILL BE PRESENT ACROSS THE REGION...AND MAY HAVE SOME LINGERING FLURRIES ACROSS OUR NE THU MORN. WOULD BE A MINIMAL SHOT SO WILL NOT INSERT INTO GRIDS AT THIS TIME. MODELS HAVE BEEN TRENDING CLOSER TO THE ECMWF...WHICH HAS BEEN THE MOST CONSISTENT MODEL DOWNPLAYING THE SOUTHWARD ADVANCEMENT OF ARCTIC AIR. STILL...THINK TEMPS WILL HAVE A HARD TIME GETTING OUT OF THE 30S FOR THU UNDER THE NW FLOW (ESPECIALLY ACROSS OUR NE). TEMPS SHOULD SLOWLY MODERATE ON FRI...WITH VALUES CLOSER TO NORMAL. SAT-MON... THIS PERIOD POSES THE MOST UNCERTAINTY...HOWEVER FORECASTER CONFIDENCE INCREASING DUE TO THE CONSISTENCY WITH THE ECMWF. AT THE BEGINNING OF THIS PERIOD...UPPER FLOW ALOFT IS STILL A WNW FLOW...WITH A CUT-OFF LOW OVER THE SWRN CONUS FINALLY EJECTING INTO THE SRN PLAINS. MODERATING TEMPS CONTINUE WITH SWRLY SFC WINDS AND SLT RIDGING OVERHEAD. A SFC LOW IS LOCATED OVER THE GREAT LAKES REGION SAT MORN...WITH SWWD EXTENDING FRONT. THIS FRONT WILL LIKELY PASS THROUGH THE REGION SATURDAY...WHILE AT THE SAME TIME UPPER LOW EJECTING INTO PLAINS TRAVELS JUST TO OUR SOUTH. A COMBINATION OF THESE POSES A SLT PRECIP THREAT FOR THE AREA...HOWEVER QPF AMOUNTS LOOK VERY LIGHT AT THIS POINT SINCE OUR CWA RESIDES IN THE MIDDLE OF THE TWO NRN AND SRN STREAMS. WILL JUST CARRY SLT CHC POPS...AND WOULD LIKELY START OFF AS LIQUID. SAT NIGHT...PRECIP SHOULD SWITCH TO -SHSN AS TEMPS AT 850MB DROP TO AROUND -12 DEGREES C. UPPER TROUGH BEHIND NRN STREAM FRONT TRIES TO BRING ARCTIC AIR INTO THE REGION...HOWEVER TREND IS TO LIGHTEN THE PUNCH...WITH THE NE CONUS REALLY EXPERIENCING THE WORST OF THE ARCTIC AIR. COULD HAVE A CHC OF FLURRIES WITH THE UPPER TROUGH PASSAGE...BUT GIVEN VERY DRY ATMS WILL NOT INSERT INTO THE GRIDS FOR SUNDAY AT THIS TIME. DESPITE THE MODELS TRENDING TOWARD KEEPING THE COLDEST TEMPS TO OUR NE...ENSEMBLES STILL SHOW TEMPS 1 STD DEV BELOW NORM SUN-MON...SO WILL TREND TOWARD ROUGHLY 3-5 DEGREES BELOW NORMAL FOR THESE DAYS. AL && .AVIATION (18Z TAFS)... EXTENSIVE LOW STRATUS WILL BE THE DOMINANT FORECAST PROBLEM FOR AVIATION CONCERNS THE NEXT 24 HRS. BASED ON OBSERVATIONAL TRENDS AND LATEST RUC/NAM SOUNDINGS... EXPECT SCT AREAS OF DRIZZLE/-SHRA TO CONTINUE THROUGH THE AFTN HOURS. THESE WILL LOCALLY REDUCE CIGS/VSBYS TO AROUND 700FT/1SM RESPECTIVELY. OTHERWISE CIGS WILL REMAIN IN THE MVFR CATEGORY THROUGH 0Z...WITH VSBYS IN THE VFR RANGE. WILL MAINTAIN 6SM -DZ BR AS PREVAILING AT SDF/LEX/BWG. INTO THIS EVENING LOWER LEVELS COOL SUCH THAT A FEW FLURRIES OR -SHSN MAY BE POSSIBLE HOWEVER COVERAGE IS NOT ENOUGH TO INCLUDE IN THE TAFS AT THIS TIME. LOW LEVEL RH FIELDS SUGGEST THAT CIGS MAY LIFT SLIGHTLY FROM LATE AFTN INTO THE EVENING AS DRIER AIR SLIDES ACROSS THE CWA...BUT ONLY TEMPORARILY. NAM FCST SOUNDINGS THEN INDICATE THAT CIGS MAY BECOME QUITE LOW (LIFR) AFTER 6Z (ESPECIALLY AT LEX) WHILE MOS GUIDANCE IS LESS PESSIMISTIC. WILL GO WITH A BLEND OF SOLUTIONS FOR THE TIME BEING. WITH HIGH PRES MOVING INTO THE REGION FROM THE PLAINS...WINDS WILL GENERALLY BE WESTERLY AND LIGHT...AOB 10KTS THROUGH THE 18Z TAF PERIOD. CS && .LMK WATCHES/WARNINGS/ADVISORIES... KY...NONE. IN...NONE. && $$ ky AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LOUISVILLE KY 245 PM EST MON JAN 22 2007 .SHORT TERM (TONIGHT-TUESDAY)... EXTENSIVE LOW CLOUDS OVER THE ENTIRE OHIO VALLEY REGION TODAY. THIS COUPLED WITH WEAK COLD ADVECTION HAS LED TO STEADY OR SLOWLY FALLING TEMPS TODAY...IN THE MID-UPPER 30S MOST PLACES AS OF 19Z. SCT PRECIP ON RADAR...AND BASED ON SPOTTER REPORTS COUPLED WITH ACARS DATA... PTYPE IS A MIX OF -RA/-SN/-PL...BUT INTENSITIES ARE VERY LIGHT. EXPECT THIS TO CONTINUE FOR THE REMAINDER OF THE AFTN HOURS. FCST SOUNDINGS SHOW LOW LEVEL LAPSE RATES STEEPENING INTO THE EVENING HOURS. THIS ALONG WITH LIFT FROM PASSING UPPER TROF WILL HELP CONTINUE POTENTIAL FOR PRECIP THIS EVENING...WILL WORD AS SLIGHT CHANCE OF -SHRA/-SHSN...HOWEVER AIRMASS ABOVE 800MB (ICE CRYSTAL LEVELS) IS FCST TO REMAIN ON THE DRY SIDE...SO PRECIP AMTS SHOULD BE LIGHT AND WE MAY END UP SEEING MORE OF A PATCHY LIGHT DRIZZLE/FLURRY TYPE DEAL. WILL MENTION ISLTD SLICK SPOTS POSSIBLE IN THE HWO FOR TONIGHT AND EARLY TUESDAY MORNING. CHANCES FOR PRECIP SHOULD DIMINISH AFTER 6Z AS UPPER WAVE PASSES OFF TO THE EAST...BUT SKIES WILL REMAIN CLOUDY PER NAM/GFS FCST SOUNDINGS. BOTH SHOW CLOUD COVER DIMINISHING TUESDAY AS DRIER AIR ADVECTS IN FROM THE W/SW...WHICH IS OBSERVED IN VISIBLE SATELLITE OVER AR/OK ATTM. HOWEVER THAT MAY BE DELAYED DUE TO VERY STRONG INVERSION SEEN AROUND 850MB. OVERALL WILL TREND TOWARD PARTLY CLOUDY WORDING IN THE AFTN TUESDAY. REGARDING TEMPS...USED A 50/50 BLEND OF NAM/GFS TEMPS WHICH YIELDED MIDDLE 20S MOST LOCATIONS FOR LOWS TONIGHT...AND UPPER 30S/LOWER 40S FOR HIGHS TUESDAY. CS .LONG TERM (TUESDAY NIGHT-MONDAY)... TUES NIGHT-WED NIGHT... THIS PERIOD BEGINS WITH THE UPPER FLOW PATTERN MAINLY ZONAL/SLIGHTLY NW. AT THE SFC...LOW PRESSURE AND ASSOCIATED FRONT EXTEND FROM HUDSON BAY SW TO SRN GREAT LAKES. A SHORTWAVE EMBEDDED IN WNW FLOW ALOFT IS LOCATED ACROSS THE NRN PLAINS. AT THIS TIME...THINK THE SFC FRONT FROM THE GREAT LAKES MAY STAY TO OUR NE FOR THE MOST PART...AND ONLY BRING A SLIGHT WIND SHIFT TO THE AREA WED MORNING. HOWEVER TIME-HEIGHT CROSS SECTIONS ACROSS OUR NE FROM THE NAM AND GFS INDICATE DEEPER MOISTURE FROM 06-12Z...EXTENDING INTO THE -5 TO -15 DEGREE C RANGE. THINK THAT ONLY TRACE AMOUNTS OF PRECIP WOULD OCCUR (IN THE FORM OF FLURRIES) SO MAY INSERT THIS INTO THE GRIDS. THINK A BETTER CHANCE RESIDES WITH THE UPPER PLAINS` SHORTWAVE DIVING SEWD ACROSS THE CWA WED NIGHT. THIS MAY HELP SPARK A FEW LIGHT SHOWERS ACROSS THE AREA...WITH THE BEST CHANCE ACROSS THE NERN CWA. THINK SLT CHC SNOW SHOWERS SHOULD DO THE TRICK. ANY PRECIP WOULD BE LIGHT IN NATURE. THU-FRI... THIS PERIOD WILL BE MAINLY DRY AS UPPER TROUGH MOVES OFF TO THE NE AND SFC HIGH PRESSURE TRIES TO NOSE IN FROM THE WEST. STILL A NW FLOW ALOFT WILL BE PRESENT ACROSS THE REGION...AND MAY HAVE SOME LINGERING FLURRIES ACROSS OUR NE THU MORN. WOULD BE A MINIMAL SHOT SO WILL NOT INSERT INTO GRIDS AT THIS TIME. MODELS HAVE BEEN TRENDING CLOSER TO THE ECMWF...WHICH HAS BEEN THE MOST CONSISTENT MODEL DOWNPLAYING THE SOUTHWARD ADVANCEMENT OF ARCTIC AIR. STILL...THINK TEMPS WILL HAVE A HARD TIME GETTING OUT OF THE 30S FOR THU UNDER THE NW FLOW (ESPECIALLY ACROSS OUR NE). TEMPS SHOULD SLOWLY MODERATE ON FRI...WITH VALUES CLOSER TO NORMAL. SAT-MON... THIS PERIOD POSES THE MOST UNCERTAINTY...HOWEVER FORECASTER CONFIDENCE INCREASING DUE TO THE CONSISTENCY WITH THE ECMWF. AT THE BEGINNING OF THIS PERIOD...UPPER FLOW ALOFT IS STILL A WNW FLOW...WITH A CUT-OFF LOW OVER THE SWRN CONUS FINALLY EJECTING INTO THE SRN PLAINS. MODERATING TEMPS CONTINUE WITH SWRLY SFC WINDS AND SLT RIDGING OVERHEAD. A SFC LOW IS LOCATED OVER THE GREAT LAKES REGION SAT MORN...WITH SWWD EXTENDING FRONT. THIS FRONT WILL LIKELY PASS THROUGH THE REGION SATURDAY...WHILE AT THE SAME TIME UPPER LOW EJECTING INTO PLAINS TRAVELS JUST TO OUR SOUTH. A COMBINATION OF THESE POSES A SLT PRECIP THREAT FOR THE AREA...HOWEVER QPF AMOUNTS LOOK VERY LIGHT AT THIS POINT SINCE OUR CWA RESIDES IN THE MIDDLE OF THE TWO NRN AND SRN STREAMS. WILL JUST CARRY SLT CHC POPS...AND WOULD LIKELY START OFF AS LIQUID. SAT NIGHT...PRECIP SHOULD SWITCH TO -SHSN AS TEMPS AT 850MB DROP TO AROUND -12 DEGREES C. UPPER TROUGH BEHIND NRN STREAM FRONT TRIES TO BRING ARCTIC AIR INTO THE REGION...HOWEVER TREND IS TO LIGHTEN THE PUNCH...WITH THE NE CONUS REALLY EXPERIENCING THE WORST OF THE ARCTIC AIR. COULD HAVE A CHC OF FLURRIES WITH THE UPPER TROUGH PASSAGE...BUT GIVEN VERY DRY ATMS WILL NOT INSERT INTO THE GRIDS FOR SUNDAY AT THIS TIME. DESPITE THE MODELS TRENDING TOWARD KEEPING THE COLDEST TEMPS TO OUR NE...ENSEMBLES STILL SHOW TEMPS 1 STD DEV BELOW NORM SUN-MON...SO WILL TREND TOWARD ROUGHLY 3-5 DEGREES BELOW NORMAL FOR THESE DAYS. AL && .AVIATION (18Z TAFS)... EXTENSIVE LOW STRATUS WILL BE THE DOMINANT FORECAST PROBLEM FOR AVIATION CONCERNS THE NEXT 24 HRS. BASED ON OBSERVATIONAL TRENDS AND LATEST RUC/NAM SOUNDINGS... EXPECT SCT AREAS OF DRIZZLE/-SHRA TO CONTINUE THROUGH THE AFTN HOURS. THESE WILL LOCALLY REDUCE CIGS/VSBYS TO AROUND 700FT/1SM RESPECTIVELY. OTHERWISE CIGS WILL REMAIN IN THE MVFR CATEGORY THROUGH 0Z...WITH VSBYS IN THE VFR RANGE. WILL MAINTAIN 6SM -DZ BR AS PREVAILING AT SDF/LEX/BWG. INTO THIS EVENING LOWER LEVELS COOL SUCH THAT A FEW FLURRIES OR -SHSN MAY BE POSSIBLE HOWEVER COVERAGE IS NOT ENOUGH TO INCLUDE IN THE TAFS AT THIS TIME. LOW LEVEL RH FIELDS SUGGEST THAT CIGS MAY LIFT SLIGHTLY FROM LATE AFTN INTO THE EVENING AS DRIER AIR SLIDES ACROSS THE CWA...BUT ONLY TEMPORARILY. NAM FCST SOUNDINGS THEN INDICATE THAT CIGS MAY BECOME QUITE LOW (LIFR) AFTER 6Z (ESPECIALLY AT LEX) WHILE MOS GUIDANCE IS LESS PESSIMISTIC. WILL GO WITH A BLEND OF SOLUTIONS FOR THE TIME BEING. WITH HIGH PRES MOVING INTO THE REGION FROM THE PLAINS...WINDS WILL GENERALLY BE WESTERLY AND LIGHT...AOB 10KTS THROUGH THE 18Z TAF PERIOD. CS && .LMK WATCHES/WARNINGS/ADVISORIES... KY...NONE. IN...NONE. && $$ ky AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LOUISVILLE KY 1217 PM EST MON JAN 22 2007 .AVIATION (18Z TAFS)... EXTENSIVE LOW STRATUS WILL BE THE DOMINANT FORECAST PROBLEM FOR AVIATION CONCERNS THE NEXT 24 HRS. BASED ON OBSERVATIONAL TRENDS AND LATEST RUC/NAM SOUNDINGS... EXPECT SCT AREAS OF DRIZZLE/-SHRA TO CONTINUE THROUGH THE AFTN HOURS. THESE WILL LOCALLY REDUCE CIGS/VSBYS TO AROUND 700FT/1SM RESPECTIVELY. OTHERWISE CIGS WILL REMAIN IN THE MVFR CATEGORY THROUGH 0Z...WITH VSBYS IN THE VFR RANGE. WILL MAINTAIN 6SM -DZ BR AS PREVAILING AT SDF/LEX/BWG. INTO THIS EVENING LOWER LEVELS COOL SUCH THAT A FEW FLURRIES OR -SHSN MAY BE POSSIBLE HOWEVER COVERAGE IS NOT ENOUGH TO INCLUDE IN THE TAFS AT THIS TIME. LOW LEVEL RH FIELDS SUGGEST THAT CIGS MAY LIFT SLIGHTLY FROM LATE AFTN INTO THE EVENING AS DRIER AIR SLIDES ACROSS THE CWA...BUT ONLY TEMPORARILY. NAM FCST SOUNDINGS THEN INDICATE THAT CIGS MAY BECOME QUITE LOW (LIFR) AFTER 6Z (ESPECIALLY AT LEX) WHILE MOS GUIDANCE IS LESS PESSIMISTIC. WILL GO WITH A BLEND OF SOLUTIONS FOR THE TIME BEING. WITH HIGH PRES MOVING INTO THE REGION FROM THE PLAINS...WINDS WILL GENERALLY BE WESTERLY AND LIGHT...AOB 10KTS THROUGH THE 18Z TAF PERIOD. CS && .PREV DISCUSSION... /ISSUED 1036 AM EST MON JAN 22 2007/ UPDATE... AREAS OF DRIZZLE OR -SHRA ARE CONTINUING OVER THE LMK CWA THIS MORNING BASED ON LOCAL RADARS. ACARS SOUNDINGS AND LATEST RUC INDICATE THAT PTYPE SHOULD REMAIN LIQUID TODAY...WITH ATMOS ABOVE 800MB/-7C REMAINING DRY. WILL INCLUDE AREAS OF DRIZZLE WITH A SLIGHT CHANCE OF RAIN SHOWERS GIVEN COVERAGE OF PRECIP ON RADAR CURRENTLY AND VSBYS NEAR 1SM AT FTK. IT`S CONCEIVABLE THAT WITHIN SPOTS OF HIGHER REFLECTIVITY/DEEPER SATURATION...THERE COULD BE A BRIEF RA/SN SHOWER...SOMETHING TO WATCH TODAY. INCOMING 12Z NAM IS SHOWING STEEP LOW LEVEL LAPSE RATES CONTINUING INTO THE EVENING HOURS...SO HAVE EXTENDED DRIZZLE/SHRA INTO THE EVENING ACROSS THE CWA. MAY SEE A TRANSITION TO FLURRIES AS LOW LEVELS COOL. TEMPS TODAY WILL BE A CHALLENGE. EXTENSIVE CLOUD COVER AND WEAK COLD ADVECTION SHOULD KEEP READINGS NEARLY STEADY. UPDATED FCST WILL BE OUT BY 11 AM EST. CS PREV DISCUSSION... /ISSUED 844 AM EST MON JAN 22 2007/ UPDATE... QUICK UPDATE TO ACCOUNT FOR PRECIP DEVELOPING FROM NEAR SDF/FTK OVER INTO SRN INDIANA AND SOUTH TO NEAR BWG. WILL REFER TO THIS AS PATCHY DRIZZLE. PTYPE BASED ON LATEST ACARS/RUC SOUNDINGS SHOULD REMAIN LIQUID (DRIZZLE) AS CRITICAL ICE CRYSTAL LAYER IS DRY. REST OF FCST UNCHANGED AT THIS TIME. CS && PREV DISCUSSION... /ISSUED 316 AM EST MON JAN 22 2007/ SHORT TERM (TODAY AND TONIGHT)... SHORT TERM MODELS SHOW VERY LITTLE DISAGREEMENT THRU THE NEXT 24 HRS...WILL LEAN TOWARDS A BLEND OF THE 21Z SREF AND THE 00Z GFS FOR THE FORECAST PERIOD. ONLY SIGNIFICANT FORECAST PROBLEM IS DEALING WITH TEMPS AND CLOUDS. MODEST POSITIVE TILT TROUGH ACROSS THE WESTERN GREAT LAKES INTO THE PLAINS...WITH CLOSED LOW ACROSS THE GADSDEN PURCHASE REGION OF THE DESERT SOUTHWEST AND WEAK SE CONUS RIDGING. SFC HI PRESSURE SITS JUST TO THE WEST OF THE REGION...PRODUCING WNW WINDS. TROUGH SHIFTS EAST FROM THE PLAINS INTO THE MS VALLEY BY AFTERNOON...BRINGING IN SLIGHTLY COLDER AIR ALOFT AT 850 MB...850 TEMPS DROPPING TO AROUND -8C. TROUGH PUSHES ON THROUGH THE MID OHIO VALLEY DURING THE OVERNIGHT PERIOD...AS SFC RIDGING NUDGES EAST IN THE REGION WITH SLIGHT 850 MB WARMING TOWARDS -4C AS THE TROUGH PUSHES EAST BY 12Z TUES. TIME SERIES OF BWG/LEX/SDF EACH SHOW SIGNIFICANT INVERSION TRAPPING MOISTURE BELOW 850 MB...WITH SFC TO 850 MB RH AVG AROUND 90-95 PERCENT THROUGH 12Z TUES. ABOVE THE 850 MB LAYER THE ATMS IS MUCH DRIER AND WARMER WITH RH AROUND 15-20 PERCENT THROUGHOUT MUCH OF THE COLUMN...AND TEMPS WARMING IN THE WSW FLOW AROUND 750 TO 700 MB TO 0C. BEFORE COOLING AS THE FLOW WEAKENS OVERNIGHT. SO WILL KEEP THE CLOUDY SKIES THROUGH THE ENTIRE PERIOD...WEAK LIFT SEEN JUST ABOVE THE MOISTURE DURING THE AFTERNOON AND WILL HAVE DRIZZLE IN AROUND NOON THRU 5PM. THE NGMMOS HAS BEEN VERY INCONSISTENT AND JUMPY THE LAST 3 RUNS SO WILL DISCOUNT...WILL LEAN TOWARDS A BLEND OF THE MET/MAV MOS THIS AFTERNOON. EACH OF THE TWO HAS SHOWED A TREND OF ABOUT 1 DEGREE COOLER FOR THE AFTERNOON HIGHS...EASILY EXPLAINABLE DUE TO THE CLOUDS CREATING LESS HEATING. WILL GO A DEGREE OR TWO WARMER FOR OVERNIGHT LOWS THAN USING A STRAIGHT BLEND OF THE TWO ALSO DUE TO THE CLOUDS. SCHOTT LONG-TERM (TUESDAY THROUGH SUNDAY)... THE LONG TERM PERIOD IS STILL CHARACTERIZED BY THE PERSISTENT MEAN RIDGE ALONG OR A LITTLE WEST OF THE WEST COAST OF THE US AND WESTERN CANADA. EARLY IN THE PERIOD ANOTHER CUTOFF LOW DEVELOPS OVER THE SOUTHWESTERN U.S. INTO NORTHWEST MEXICO THAT COULD IMPACT OUR REGION OVER THE WEEKEND. AT THE SAME TIME...A STRONG SHORT WAVE MOVING INTO NORTHWEST CANADA TO THE SOUTHEAST OF AK...BRIEFLY FLATTENS THE WESTERN CANADA RIDGE AND THEN DIGS SOUTHEAST INTO THE SOUTHERN HUDSON BAY REGION AND IS FOLLOWED BY A SERIES OF OTHER SHORT WAVES THAT PROMISE TO KEEP THIS NORTHERN STREAM AS THE CONTROLLING WEATHER MAKER FOR OUR REGION BEFORE BREAKING DOWN A BIT OVER NEXT WEEKEND. DURING THE WEDNESDAY-THURSDAY TIME FRAME THIS FIRST CLIPPER LIKE SYSTEM BRINGS ANOTHER SURGE OF ARCTIC AIR SOUTHWARD INTO THE REGION. THIS COULD LEAD TO A PERIOD OF SNOW SHOWERS AND/OR FLURRIES FOR A TIME DURING THE ABOVE MENTIONED COUPLE OF DAYS. THIS IS MORE OR LESS IN LINE WITH OUR CURRENT FCST. OVER THE WEEKEND THE NORTHERN STREAM IS MERGED BY THE REMNANTS OF THE SOUTHWESTERN CUTOFF AND LEADS TO ANOTHER CHC FOR SOME RAIN OR SNOW. THIS COULD BE ANOTHER SIMILAR SCENARIO TO THIS PAST WEEKEND. BOTH THE ECMWF AND GFS SHOW A SIMILAR TREND BUT WITH SOME SIGNIFICANT TIMING DIFFERENCES...THIS WILL HAVE TO BE WATCHED CLOSELY. ONLY REAL CHANGES TO THE CURRENT FCSTS WERE SOME MINOR TWEAKS WITH THE HOURLY AND MAX AND MIN TEMPS FOR BETTER CONSISTENCY WITH THE SURROUNDING FA`S. --21 && .LMK WATCHES/WARNINGS/ADVISORIES... KY...NONE. IN...NONE. && $$ ky AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE LOUISVILLE KY 1036 AM EST MON JAN 22 2007 .UPDATE... AREAS OF DRIZZLE OR -SHRA ARE CONTINUING OVER THE LMK CWA THIS MORNING BASED ON LOCAL RADARS. ACARS SOUNDINGS AND LATEST RUC INDICATE THAT PTYPE SHOULD REMAIN LIQUID TODAY...WITH ATMOS ABOVE 800MB/-7C REMAINING DRY. WILL INCLUDE AREAS OF DRIZZLE WITH A SLIGHT CHANCE OF RAIN SHOWERS GIVEN COVERAGE OF PRECIP ON RADAR CURRENTLY AND VSBYS NEAR 1SM AT FTK. IT`S CONCEIVABLE THAT WITHIN SPOTS OF HIGHER REFLECTIVITY/DEEPER SATURATION...THERE COULD BE A BRIEF RA/SN SHOWER...SOMETHING TO WATCH TODAY. INCOMING 12Z NAM IS SHOWING STEEP LOW LEVEL LAPSE RATES CONTINUING INTO THE EVENING HOURS...SO HAVE EXTENDED DRIZZLE/SHRA INTO THE EVENING ACROSS THE CWA. MAY SEE A TRANSITION TO FLURRIES AS LOW LEVELS COOL. TEMPS TODAY WILL BE A CHALLENGE. EXTENSIVE CLOUD COVER AND WEAK COLD ADVECTION SHOULD KEEP READINGS NEARLY STEADY. UPDATED FCST WILL BE OUT BY 11 AM EST. CS && .PREV DISCUSSION... /ISSUED 844 AM EST MON JAN 22 2007/ UPDATE... QUICK UPDATE TO ACCOUNT FOR PRECIP DEVELOPING FROM NEAR SDF/FTK OVER INTO SRN INDIANA AND SOUTH TO NEAR BWG. WILL REFER TO THIS AS PATCHY DRIZZLE. PTYPE BASED ON LATEST ACARS/RUC SOUNDINGS SHOULD REMAIN LIQUID (DRIZZLE) AS CRITICAL ICE CRYSTAL LAYER IS DRY. REST OF FCST UNCHANGED AT THIS TIME. CS PREV DISCUSSION... /ISSUED 316 AM EST MON JAN 22 2007/ SHORT TERM (TODAY AND TONIGHT)... SHORT TERM MODELS SHOW VERY LITTLE DISAGREEMENT THRU THE NEXT 24 HRS...WILL LEAN TOWARDS A BLEND OF THE 21Z SREF AND THE 00Z GFS FOR THE FORECAST PERIOD. ONLY SIGNIFICANT FORECAST PROBLEM IS DEALING WITH TEMPS AND CLOUDS. MODEST POSITIVE TILT TROUGH ACROSS THE WESTERN GREAT LAKES INTO THE PLAINS...WITH CLOSED LOW ACROSS THE GADSDEN PURCHASE REGION OF THE DESERT SOUTHWEST AND WEAK SE CONUS RIDGING. SFC HI PRESSURE SITS JUST TO THE WEST OF THE REGION...PRODUCING WNW WINDS. TROUGH SHIFTS EAST FROM THE PLAINS INTO THE MS VALLEY BY AFTERNOON...BRINGING IN SLIGHTLY COLDER AIR ALOFT AT 850 MB...850 TEMPS DROPPING TO AROUND -8C. TROUGH PUSHES ON THROUGH THE MID OHIO VALLEY DURING THE OVERNIGHT PERIOD...AS SFC RIDGING NUDGES EAST IN THE REGION WITH SLIGHT 850 MB WARMING TOWARDS -4C AS THE TROUGH PUSHES EAST BY 12Z TUES. TIME SERIES OF BWG/LEX/SDF EACH SHOW SIGNIFICANT INVERSION TRAPPING MOISTURE BELOW 850 MB...WITH SFC TO 850 MB RH AVG AROUND 90-95 PERCENT THROUGH 12Z TUES. ABOVE THE 850 MB LAYER THE ATMS IS MUCH DRIER AND WARMER WITH RH AROUND 15-20 PERCENT THROUGHOUT MUCH OF THE COLUMN...AND TEMPS WARMING IN THE WSW FLOW AROUND 750 TO 700 MB TO 0C. BEFORE COOLING AS THE FLOW WEAKENS OVERNIGHT. SO WILL KEEP THE CLOUDY SKIES THROUGH THE ENTIRE PERIOD...WEAK LIFT SEEN JUST ABOVE THE MOISTURE DURING THE AFTERNOON AND WILL HAVE DRIZZLE IN AROUND NOON THRU 5PM. THE NGMMOS HAS BEEN VERY INCONSISTENT AND JUMPY THE LAST 3 RUNS SO WILL DISCOUNT...WILL LEAN TOWARDS A BLEND OF THE MET/MAV MOS THIS AFTERNOON. EACH OF THE TWO HAS SHOWED A TREND OF ABOUT 1 DEGREE COOLER FOR THE AFTERNOON HIGHS...EASILY EXPLAINABLE DUE TO THE CLOUDS CREATING LESS HEATING. WILL GO A DEGREE OR TWO WARMER FOR OVERNIGHT LOWS THAN USING A STRAIGHT BLEND OF THE TWO ALSO DUE TO THE CLOUDS. SCHOTT LONG-TERM (TUESDAY THROUGH SUNDAY)... THE LONG TERM PERIOD IS STILL CHARACTERIZED BY THE PERSISTENT MEAN RIDGE ALONG OR A LITTLE WEST OF THE WEST COAST OF THE US AND WESTERN CANADA. EARLY IN THE PERIOD ANOTHER CUTOFF LOW DEVELOPS OVER THE SOUTHWESTERN U.S. INTO NORTHWEST MEXICO THAT COULD IMPACT OUR REGION OVER THE WEEKEND. AT THE SAME TIME...A STRONG SHORT WAVE MOVING INTO NORTHWEST CANADA TO THE SOUTHEAST OF AK...BRIEFLY FLATTENS THE WESTERN CANADA RIDGE AND THEN DIGS SOUTHEAST INTO THE SOUTHERN HUDSON BAY REGION AND IS FOLLOWED BY A SERIES OF OTHER SHORT WAVES THAT PROMISE TO KEEP THIS NORTHERN STREAM AS THE CONTROLLING WEATHER MAKER FOR OUR REGION BEFORE BREAKING DOWN A BIT OVER NEXT WEEKEND. DURING THE WEDNESDAY-THURSDAY TIME FRAME THIS FIRST CLIPPER LIKE SYSTEM BRINGS ANOTHER SURGE OF ARCTIC AIR SOUTHWARD INTO THE REGION. THIS COULD LEAD TO A PERIOD OF SNOW SHOWERS AND/OR FLURRIES FOR A TIME DURING THE ABOVE MENTIONED COUPLE OF DAYS. THIS IS MORE OR LESS IN LINE WITH OUR CURRENT FCST. OVER THE WEEKEND THE NORTHERN STREAM IS MERGED BY THE REMNANTS OF THE SOUTHWESTERN CUTOFF AND LEADS TO ANOTHER CHC FOR SOME RAIN OR SNOW. THIS COULD BE ANOTHER SIMILAR SCENARIO TO THIS PAST WEEKEND. BOTH THE ECMWF AND GFS SHOW A SIMILAR TREND BUT WITH SOME SIGNIFICANT TIMING DIFFERENCES...THIS WILL HAVE TO BE WATCHED CLOSELY. ONLY REAL CHANGES TO THE CURRENT FCSTS WERE SOME MINOR TWEAKS WITH THE HOURLY AND MAX AND MIN TEMPS FOR BETTER CONSISTENCY WITH THE SURROUNDING FA`S. --21 && .LMK WATCHES/WARNINGS/ADVISORIES... KY...NONE. IN...NONE. && $$ ky AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE LOUISVILLE KY 844 AM EST MON JAN 22 2007 .UPDATE... QUICK UPDATE TO ACCOUNT FOR PRECIP DEVELOPING FROM NEAR SDF/FTK OVER INTO SRN INDIANA AND SOUTH TO NEAR BWG. WILL REFER TO THIS AS PATCHY DRIZZLE. PTYPE BASED ON LATEST ACARS/RUC SOUNDINGS SHOULD REMAIN LIQUID (DRIZZLE) AS CRITICAL ICE CRYSTAL LAYER IS DRY. REST OF FCST UNCHANGED AT THIS TIME. CS && .PREV DISCUSSION... /ISSUED 316 AM EST MON JAN 22 2007/ SHORT TERM (TODAY AND TONIGHT)... SHORT TERM MODELS SHOW VERY LITTLE DISAGREEMENT THRU THE NEXT 24 HRS...WILL LEAN TOWARDS A BLEND OF THE 21Z SREF AND THE 00Z GFS FOR THE FORECAST PERIOD. ONLY SIGNIFICANT FORECAST PROBLEM IS DEALING WITH TEMPS AND CLOUDS. MODEST POSITIVE TILT TROUGH ACROSS THE WESTERN GREAT LAKES INTO THE PLAINS...WITH CLOSED LOW ACROSS THE GADSDEN PURCHASE REGION OF THE DESERT SOUTHWEST AND WEAK SE CONUS RIDGING. SFC HI PRESSURE SITS JUST TO THE WEST OF THE REGION...PRODUCING WNW WINDS. TROUGH SHIFTS EAST FROM THE PLAINS INTO THE MS VALLEY BY AFTERNOON...BRINGING IN SLIGHTLY COLDER AIR ALOFT AT 850 MB...850 TEMPS DROPPING TO AROUND -8C. TROUGH PUSHES ON THROUGH THE MID OHIO VALLEY DURING THE OVERNIGHT PERIOD...AS SFC RIDGING NUDGES EAST IN THE REGION WITH SLIGHT 850 MB WARMING TOWARDS -4C AS THE TROUGH PUSHES EAST BY 12Z TUES. TIME SERIES OF BWG/LEX/SDF EACH SHOW SIGNIFICANT INVERSION TRAPPING MOISTURE BELOW 850 MB...WITH SFC TO 850 MB RH AVG AROUND 90-95 PERCENT THROUGH 12Z TUES. ABOVE THE 850 MB LAYER THE ATMS IS MUCH DRIER AND WARMER WITH RH AROUND 15-20 PERCENT THROUGHOUT MUCH OF THE COLUMN...AND TEMPS WARMING IN THE WSW FLOW AROUND 750 TO 700 MB TO 0C. BEFORE COOLING AS THE FLOW WEAKENS OVERNIGHT. SO WILL KEEP THE CLOUDY SKIES THROUGH THE ENTIRE PERIOD...WEAK LIFT SEEN JUST ABOVE THE MOISTURE DURING THE AFTERNOON AND WILL HAVE DRIZZLE IN AROUND NOON THRU 5PM. THE NGMMOS HAS BEEN VERY INCONSISTENT AND JUMPY THE LAST 3 RUNS SO WILL DISCOUNT...WILL LEAN TOWARDS A BLEND OF THE MET/MAV MOS THIS AFTERNOON. EACH OF THE TWO HAS SHOWED A TREND OF ABOUT 1 DEGREE COOLER FOR THE AFTERNOON HIGHS...EASILY EXPLAINABLE DUE TO THE CLOUDS CREATING LESS HEATING. WILL GO A DEGREE OR TWO WARMER FOR OVERNIGHT LOWS THAN USING A STRAIGHT BLEND OF THE TWO ALSO DUE TO THE CLOUDS. SCHOTT LONG-TERM (TUESDAY THROUGH SUNDAY)... THE LONG TERM PERIOD IS STILL CHARACTERIZED BY THE PERSISTENT MEAN RIDGE ALONG OR A LITTLE WEST OF THE WEST COAST OF THE US AND WESTERN CANADA. EARLY IN THE PERIOD ANOTHER CUTOFF LOW DEVELOPS OVER THE SOUTHWESTERN U.S. INTO NORTHWEST MEXICO THAT COULD IMPACT OUR REGION OVER THE WEEKEND. AT THE SAME TIME...A STRONG SHORT WAVE MOVING INTO NORTHWEST CANADA TO THE SOUTHEAST OF AK...BRIEFLY FLATTENS THE WESTERN CANADA RIDGE AND THEN DIGS SOUTHEAST INTO THE SOUTHERN HUDSON BAY REGION AND IS FOLLOWED BY A SERIES OF OTHER SHORT WAVES THAT PROMISE TO KEEP THIS NORTHERN STREAM AS THE CONTROLLING WEATHER MAKER FOR OUR REGION BEFORE BREAKING DOWN A BIT OVER NEXT WEEKEND. DURING THE WEDNESDAY-THURSDAY TIME FRAME THIS FIRST CLIPPER LIKE SYSTEM BRINGS ANOTHER SURGE OF ARCTIC AIR SOUTHWARD INTO THE REGION. THIS COULD LEAD TO A PERIOD OF SNOW SHOWERS AND/OR FLURRIES FOR A TIME DURING THE ABOVE MENTIONED COUPLE OF DAYS. THIS IS MORE OR LESS IN LINE WITH OUR CURRENT FCST. OVER THE WEEKEND THE NORTHERN STREAM IS MERGED BY THE REMNANTS OF THE SOUTHWESTERN CUTOFF AND LEADS TO ANOTHER CHC FOR SOME RAIN OR SNOW. THIS COULD BE ANOTHER SIMILAR SCENARIO TO THIS PAST WEEKEND. BOTH THE ECMWF AND GFS SHOW A SIMILAR TREND BUT WITH SOME SIGNIFICANT TIMING DIFFERENCES...THIS WILL HAVE TO BE WATCHED CLOSELY. ONLY REAL CHANGES TO THE CURRENT FCSTS WERE SOME MINOR TWEAKS WITH THE HOURLY AND MAX AND MIN TEMPS FOR BETTER CONSISTENCY WITH THE SURROUNDING FA`S. --21 && .LMK WATCHES/WARNINGS/ADVISORIES... KY...NONE. IN...NONE. && $$ ky AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE LOUISVILLE KY 730 PM EST SUN JAN 21 2007 ...UPDATE FOR TONIGHT... BASED ON CURRENT TEMPERATURE TRENDS AND FORECAST TEMPERATURES FROM THE RUC MODEL WE ARE GOING TO CANCEL THE WINTER WEATHER ADVISORY FOR THE OVERNIGHT PERIOD ACROSS SOUTH CENTRAL INDIANA AND THE NORTHERN PORTION OF CENTRAL KENTUCKY. FORECAST UPDATE WILL BE OUT BY 7:45PM. --JA 345PM DISCUSSION BELOW... THE MAIN STORM SYSTEM IS NOW OFF TO OUR EAST...HOWEVER VERY HIGH MOISTURE LEVELS REMAIN IN ITS WAKE AT AND BELOW 850HPA. THIS MOISTURE WILL BE VERY RELUCTANT TO LEAVE THE AREA...AND IN FACT LOOKS TO STICK AROUND THROUGHOUT THE SHORT TERM. INDEED SATELLITE PICTURES AND SURFACE OBSERVATIONS SHOW THIS MOISTURE AND CLOUDINESS STRETCHING ALL THE WAY WEST TO THE GREAT PLAINS AND NORTH TO THE CANADIAN BORDER. AS A RESULT WE EXPECT OVERCAST CONDITIONS TO CONTINUE TONIGHT AND MONDAY. THE BIG CHALLENGE OF THE FORECAST IS WHETHER OR NOT ANYTHING WILL FALL FROM THOSE CLOUDS. PATCHY DRIZZLE HAS BEEN SEEN THROUGHOUT THE REGION TODAY. NOT MUCH REASON TO BELIEVE THIS WON/T CONTINUE TO BE THE CASE TONIGHT INTO TOMORROW. TURNING THEN TO SURFACE TEMPERATURES AND VERTICAL TEMPERATURE PROFILES IT APPEARS THAT SOME FREEZING DRIZZLE WILL BE POSSIBLE EARLY MONDAY. TEMPERATURES SHOULD EDGE TO AROUND OR JUST A DEGREE OR TWO BELOW FREEZING TONIGHT. ANY FREEZING DRIZZLE THAT MIGHT FALL WOULD BE VERY LIGHT AND SPOTTY. NORTH OF INTERSTATE 64 TEMPERATURES WILL BE COOL ENOUGH FOR THE CHANCE OF SOME FREEZING DRIZZLE BETWEEN MIDNIGHT AND MID-MORNING. ALONG THE INTERSTATE 64 CORRIDOR INCLUDING LOUISVILLE AND LEXINGTON...THE WINDOW FOR FREEZING DRIZZLE WILL BE SHORT...PRIMARILY FROM ABOUT 5AM TO 9AM. HOWEVER...THE TIMING OF THIS COULDN/T BE WORSE AS IT WILL OCCUR DURING THE MONDAY MORNING RUSH HOUR. SO...ALTHOUGH THIS WILL BE A VERY MINOR EVENT...SINCE IT/S OCCURRING AT SUCH A SIGNIFICANT TIME OF DAY WE WOULD LIKE TO HIGHLIGHT IT. AFTER COORDINATION WITH SURROUNDING OFFICES WILL GO AHEAD AN ISSUE A WINTER WEATHER ADVISORY FOR EARLY MONDAY MORNING FOR ABOUT THE NORTHERN HALF OF THE LOUISVILLE CWFA. IT WILL ONLY BE VALID FOR A FEW HOURS IN THE LOUISVILLE AND LEXINGTON AREAS. ALSO...WITH TEMPERATURES HOVERING RIGHT AROUND 32 DEGREES...IT MAY BE MORE OF AN ISSUE IN COOLER RURAL LOCALES AND NOT MUCH OF A PROBLEM AT ALL WITHIN THE URBAN CENTERS. THANKS TO IND...ILN...JKL...PAH...AND LOCAL MEDIA FOR COORD. 13 .LONG-TERM (MONDAY NIGHT THROUGH SUNDAY)... MONDAY NIGHT-TUESDAY NIGHT... PESKY LOW STRATUS WILL CONTINUE MONDAY NIGHT INTO TUESDAY MORNING PER NAM/GFS LOW-LEVEL MOISTURE FIELDS. TIME-HEIGHT CROSS-SECTIONS FROM BOTH MODELS INDICATE SATURATED 1000-850MB LAYER THROUGH AT LEAST 09Z TUES MORN. SHORTWAVE CURRENTLY OVER NRN MONTANA IS PROGGED TO DIVE SOUTHEAST...AND THIS TROUGH SHOULD PASS OVER THE REGION BETWEEN 00-12Z TUES. WITH THE LOW-LEVEL MOISTURE...THIS SHOULD BE ENOUGH FORCING TO GENERATE FLURRIES (BL TEMPS APPEAR TOO COLD FOR FRZNG DRZL). HAVE INSERTED FLURRIES CWA-WIDE 00-12Z TUESDAY. TROUGH SHOULD BE TO OUR ESE TUES MORN...SO THE AREA SHOULD HAVE A BETTER CHANCE OF STARTING TO CLEAR OUT. NONETHELESS CLOUDS WILL BE SLOW TO ERODE...SO KEPT MOSTLY CLOUDY SKIES IN FOR MUCH OF TUESDAY BEFORE SHORT-LIVED PARTIAL CLEARING TAKES PLACE TUES NIGHT. TEMPS COULD BE TRICKY DEPENDING ON CLOUD COVER...BUT THINK SOME SUNSHINE MAY PEEK IN LATE IN THE DAY...ENOUGH TO YIELD TEMPS AOB NORMS. WEDNESDAY-SUNDAY... A SFC CLIPPER SYSTEM IN THE ACTIVE NORTHERN STREAM WILL DIVE SEWD ACROSS THE GREAT LAKES MIDDAY WEDNESDAY. AHEAD OF THIS OUR WINDS SHOULD COME AROUND TO THE SOUTHWEST...YIELDING TEMPS A COUPLE OF DEGREES WARMER THAN ON TUESDAY...PERHAPS REACHING THE MID 40S ACROSS SRN KY. THIS CLIPPER SYSTEM WILL ALSO BRING ABOUT A CHANCE FOR SOME LIGHT PRECIP WEDNESDAY...MAINLY AFTER NOON...THROUGH THURSDAY. THE EXACT TRACK OF THE CLIPPER WILL DETERMINE P-TYPE AND AMOUNT. EVEN THOUGH TEMPS WED SHOULD YIELD RAIN DURING THE DAY...TEMPS SHOULD DROP INTO THE UPPER 20S THU MORN WHICH WOULD ALLOW ANY SNOW THAT FORMS TO STICK TO SURFACES. AT THIS TIME...LOOKS LIKE THE NORTHERN BLUEGRASS AND SOUTHEAST INDIANA WOULD HAVE THE BEST CHANCE AT SEEING SOME LIGHT SNOW ACCUMS WED NIGHT-THU MIDDAY. CURRENTLY KEEPING SNOW TOTALS AROUND A HALF INCH OR LESS SINCE GFS ENSEMBLES BARELY SHOW ANY QPF AT ALL. AND SINCE THE TREND OVER THE PAST TWO MODEL RUNS HAS BEEN TO WEAKEN THE COLD PUNCH THU...DO NOT WANT TO GET CARRIED AWAY WITH AMOUNTS JUST YET IF THE CLIPPER ENDS UP TRACKING FURTHER TO THE NE. MAY HAVE TO ALTER ONE WAY OR ANOTHER AS THIS SYSTEM APPROACHES. DEPENDING ON IF ANY SNOW FALLS AND STICKS THURSDAY...THU NIGHT TEMPS COULD BE A CHALLENGE AS SFC HIGH PRESSURE WORKS IN FROM THE SW AND 850MB TEMPS RAMP UP (STILL COOL THOUGH). COULD HAVE UPPER TEENS NE TO MID 20S SW FOR THU NIGHT LOWS. FRIDAY AND FRIDAY NIGHT ALSO APPEARS DRY WITH HIGH PRESSURE OVERHEAD. AFTER THE QUICK COOL DOWN THU-FRI MORN...TEMPS WILL MODERATE THROUGH SAT MORN...WITH VALUES RISING TO AOB NORMALS AGAIN. SATURDAY MORNING...ANOTHER SFC LOW TRACKS ACROSS THE GREAT LAKES...WITH AN ASSOCIATED FRONT EXTENDING INTO THE ERN PLAINS. THOUGH MOISTURE IS NOT THAT IMPRESSIVE...THE ARCTIC FRONT PASSES THROUGH THE CWA SAT NIGHT-SUN MORN. HAVE INSERTED SLT CHC RAIN SAT AFT AND SLT CHC SNOW SAT NIGHT-SUN MORN. BEHIND THE FRONT...ECMWF (THE MOST CONSISTENT MODEL OF LATE) AND GFS BOTH POINT AT COLD ARCTIC AIR PUSHING INTO THE CWA. IF (AND ONLY IF) THIS TREND HOLDS UP...WOULD HAVE THE COLDEST AIR OF THE SEASON SUN-MON. HPC MAX TEMPS IN THE 30S FOR HIGHS LOOKED REASONABLE FOR SAT...SO DID NOT ALTER. AL && .LMK WATCHES/WARNINGS/ADVISORIES... KY...NONE. IN...NONE. && $$ ky AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE CARIBOU ME 924 PM EST MON JAN 22 2007 .SYNOPSIS...WEAK HIGH PRESSURE WILL HOLD MAINLY ACROSS THE NORTHERN PORTION OF THE REGION TONIGHT WITH FAIR...CALM AND COLD CONDITIONS...WHILE LOW PRESSURE TRACKS WELL SOUTH OF THE REGION TONIGHT AND SOUTH OF NOVA SCOTIA TUESDAY...BRINGING MORE CLOUDS AND A CHANCE OF SNOW SHOWERS TO DOWNEAST MAINE. AFTERWARDS...A COLD FRONT WILL APPROACH FROM THE WEST WEDNESDAY AND CROSS THE REGION WEDNESDAY NIGHT...ACCOMPANIED BY SNOW SHOWERS. BEHIND THIS FRONT...BRISK AND VERY COLD CONDITIONS ARE ANTICIPATED FOR THE END OF THE WEEK. && .UPDATE /REST OF TONIGHT/... BUMPED UP POPS OVER INTERIOR DOWNEAST AND COASTAL SITES TO 50%. LOOKS LIKE BEST CHC OF SNOW WILL REMAIN IN GYX/S CWA AND OUT OVER THE WATER. LATEST RUC (21Z) & GFS MATCHING PRETTY WELL PER LATEST RADAR & OBS. DECISION WAS TO BOOST OVERNIGHT MINS UP A FEW DEGREES PER RMTA & HYDROVIEW SITES. CLOUDS (MID/HIGH LVL) MOVING ACROSS MUCH OF THE CWA WILL HALT TEMPS FROM PLUMMETING INITIALLY. COULD SEE SOME PARTIAL CLEARING ACROSS THE N EARLY TUESDAY MORNING TO ALLOW TEMPS TO FALL AGAIN BEFORE SUNRISE. && .PREV DISCUSSION... SHORT TERM /TONIGHT THROUGH WEDNESDAY/... A WEAK S/WV APCHG FROM THE GREAT LKS WILL KEEP CLDS OVR DOWNEAST MAINE TNGT INTO TUE MORN...WITH CHC SN SHWR POPS MSLY FROM ZONES 15 THRU 17 TO THE COAST. ACROSS THE N...SKIES WILL REMAIN CLR TO PTCLDY...WITH IDEAL RADIATIONAL COOLING POTENTIAL IF SKIES STAY CLR ENOUGH. BIG DIFFERENCES BETWEEN MOS GUIDANCES FOR OVRNGT LOWS FOR NRN SITES AS EVIDENT BY NAM GUIDANCE GIVING PQI A LOW OF ZERO AND THE MAV -20. ATTM...WE WILL SPLIT THE DIFFERENCE OVR MOST SITES ACROSS THE N...BUT WILL ASSIGN -20 VALUES TO THE ALLAGASH AND OTHER COLD LOW LYING AREAS OF ZONES 1..3 AND 4 (NORTHWEST ME). THE NEXT S/WV ASSOCIATED WITH A STRONG ERN CAN VORTEX IS XPCTD TO BEGIN AFFECTING NRN PTNS OF THE FA LATE TUESDAY AS THE SYSTEM DIGS SE FROM CNTRL QB...WITH SN SHWRS CONTG INTO WED AS AN ARCTIC FRONT MAKES IT WAY THRU THE FA WED NGT. THE END TIMING OF THE SN SHWRS IS SOMEWHAT UNCERTAIN...BEING DEPENDENT ON THE TIMING OF THE ARCTIC FRONT...SO FOR NOW WE KEPT CHC N SHWRS GOING...SPCLYN... THRU ALL OF WED. MOST FCST GRIDS ARE MSLY BASED ON GFS DATA...WITH SOME COMPONENT OF NAM DATA. LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/... ARCTIC FRONT MOVES ACROSS THE REGION WEDNESDAY NIGHT WITH PERHAPS SCATTERED SNOW SHOWERS MAINLY ACROSS NORTHERN SECTIONS. EVEN THOUGH THE LEADING EDGE OF THE ARCTIC FRONT COMES THROUGH WEDNESDAY NIGHT THE REAL SURGE OF COLD AIR WILL TAKE PLACE DURING THE DAY ON THURSDAY AS POLAR VORTEX DIGS INTO NEW ENGLAND BY THURSDAY NIGHT. INDICATIONS ARE THAT THE CORE OF COLD AIR WILL MOVE THROUGH VERMONT AND NEW HAMPSHIRE EARLY FRIDAY MORNING. EXPECT BRISK CONDITIONS ON THURSDAY AS COLD AIR DRAINS INTO NEW ENGLAND BUT FRIDAY APPEARS TO BE THE WINDIEST AND COLDEST DAY AS UPPER POLAR VORTEX MOVES SOUTH OF NEW ENGLAND. WEAK HIGH PRESSURE WILL THEN BUILD OVER THE REGION FOR THE WEEKEND. AVIATION /19Z-18Z/... MAINLY VFR XPCTD...BUT MORE IN THE WAY OF LOW VFR AND PERHAPS MVFR CIGS AND VSBYS POSSIBLE LATE TNGT INTO TUE FOR KBGR AND KBHB. MARINE... SHORT TERM: NO HEADLINES ANTICIPATED ATTM WITH SEAS AND WINDS LIGHT/LOW FOR THIS TIME OF YEAR. LONG TERM: ARCTIC FRONT WILL CROSS THE WATERS WEDNESDAY NIGHT WITH FRESH SURGE OF COLD AIR WITH SCA CONDITIONS THURSDAY INTO FRIDAY. && .CAR WATCHES/WARNINGS/ADVISORIES... ME...NONE. MARINE...NONE. && $$ .UPDATE...HEWITT me AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 335 PM EST TUE JAN 23 2007 .DISCUSSION... 12Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW COLD NW FLOW ACRS THE UPR GRT LKS BTWN WRN RDG/ERN TROF IN CLASSIC NEGATIVE NAO/ POSITIVE PNA PATTERN. SHRTWV PLUNGING SEWD THRU THIS FLOW NOW MOVING INTO LK HURON DRAGGED A COLD FNT ACRS THE FA EARLIER IN THE DAY THAT TRIGGERED NMRS -SHSN NEAR LK SUP. SINCE ANTECEDENT AIRMASS WAS ON THE DRY SIDE PER 12Z GRB RAOB AND DEEPER MSTR CONFINED WELL TO THE S WITHIN SRN BRANCH FLOW...LTL SN FELL ACRS THE SCNTRL AWAY FM LK MOISTENING. VSBL STLT IMAGERY SHOWS MULTIPLE LES BANDS HAVE DVLPD IN THE NW FLOW OVER LK SUP BTWN LO PRES NEAR JAMES BAY/ARCTIC HI PRES NR LK WINNIPEG AND FOLLOWING THE FROPA AS COLD AIR (12Z H85 TEMP AT YPL -20C) FLOWING ACRS THE RELATIVELY WARM LK WATERS (1-3C PER GLERL ANALYSIS). HOWEVER...DRYNESS OF UPSTREAM AIR AS EVIDENCED BY 12Z PWAT OF 0.09 INCH AT INL AND 0.05 INCH AT YPL/SFC DWPTS ARND -5F UPSTREAM/NEARLY CLR SKIES FM THE MN ARROWHEAD-LK NIPIGON-FARTHER NW ONTARIO AS WELL AS DNVA/SHARP SUBSIDENCE IN THE WAKE OF SHRTWV HAVE CAUSED RELATIVELY WIDE SPACING BTWN THE BANDS AND CAUSED THE BACK EDGE OF THE LK CLD TO PUSH STEADILY SEWD... ESPECIALLY OVER WRN LK SUP. NEXT SHRTWV OF CONCERN NOW MOVING INTO NRN SASKATCHEWAN. MAIN FCST CONCERNS THE NEXT COUPLE OF DAYS IS TIMING OF SHRTWVS DROPPING SEWD IN THE NW FLOW ALF AND RELATED LES AMTS/TRENDS. FOR TNGT...SHRTWV RDGING BTWN DEPARTING SYS AND SHRTWV NOW OVER NRN SASKATCHEWAN THAT IS FCST TO PUSH INTO NW ONTARIO BY 12Z WED WL DOMINATE...RESULTING IN INVRN SINKING TO 3-4K FT. LES WL CONTINUE IN LINGERING LLVL NW FLOW...BUT CONSIDERING THE VERY DRY NATURE OF THE INCOMING AIRMASS AND WEAKENING CYC FLOW/RELATIVELY WEAK LLVL CNVGC THRU THE NGT...EXPECT LES AMTS TO BE LESS THAN SUGGESTED BY LES CHART (UP TO 3-5 INCHES/12 HRS)...ESPECIALLY ACRS THE W WITH SHORTER FETCH LENGTH. SO NO HEADLINES WL BE NECESSARY. WL HEDGE BLO EVEN THE LO END OF MOS GUIDANCE FOR MIN TEMPS ESPECIALLY AWAY FM LK MOISTENING CONSIDERING THE UPSTREAM DRY AIR. GOING FCST TMINS LOOK RSNBL. ON WED...SHRTWV FCST TO DIG SHARPLY TO NEAR THE CWA/WI BORDER BY 00Z THU. FAIRLY STRG DPVA/H85-5 QVECTOR CNVGC FCST TO IMPACT THE FA ON THE CYC SIDE OF THE H5 VORT TRACK...BUT ISENTROPIC LIFT/MSTR (PWAT NO MORE THAN 0.20 INCH) WL BE LIMITED. EXPECT NO MORE THAN SCT -SHSN/FLURRIES ACRS THE SCNTRL...BUT WL ELEVATE POPS TO LIKELY NR LK SUP CONSIDERING THE EXTRA MOISTENING OFF THE WATER/STRG DYNAMICS ON CYC SIDE OF SHRTWV PASSAGE. GIVEN THE LACK OF ISENTROPIC LIFT WITH H85 TEMPS SLOWLY FALLING THRU THE DAY AND EXPECTED CLD COVER... PREFER THE LO END OF MOS GUIDANCE (GFS MOS) FOR MAX TEMPS. LOOK FOR LES IN THE NLY FLOW LEFT IN THE WAKE OF SHRTWV THAT IS FCST TO DIG INTO THE OH VALLEY BY 12Z THU AS ONE OF THE COLDEST AIRMASSES OF THE SEASON DRIVES INTO THE AREA. 12Z UKMET/ECMWF/NAM SHOW H85 TEMPS FALLING TO -24C OVER THE E TO -20C OVER THE W BY 12Z THU. ALTHOUGH NAM FCST SDNGS HINT THAT DEEP MSTR WL LINGER THRU THE NGT... PREFER THE DRIER GFS FCST PROFILES...ESPECIALLY AFT A REINFORCING SHRTWV/ASSOCIATED DPVA AND H85-5 QVECTOR CNVGC PASS BY ARND 06Z. ALTHOUGH THE SETUP FOR LES LOOKS IMPRESSIVE...ESPECIALLY IN THE N WIND FVRD SN BELTS DOWNWIND OF THE LONGER FETCH ACRS ERN LK SUP WHERE INCOMING DRY AIR WL HAVE MORE OPPORTUNITY TO MOISTEN... IMPACT OF THIS DRY AIR/VERY LO TEMPS NOT FVRBL FOR OPTIMUM SN GROWTH/ RELATIVELY WEAK AND TRANSIENT FCST LLVL CNVGC WITH VEERING LLVL WINDS SUG LES WL NOT BE AS SGNFT AS LES CHART WOULD SUG. BUT WITH IMPACT OF DPVA ASSOCIATED WITH REINFORCING SHRTWV...LATER SHIFTS MAY NEED TO CONSIDER NEED FOR LES ADVY IN THE N WIND FVRD SN BELTS E OF THE HURON MTNS WHERE FCST DYNAMICS APPEAR STRONGER AND LLVL CNVGC MORE PERSISTENT IN LONGER FETCH. EXPECT LES TO DIMINISH SLOWLY ON THU AS HGTS RISE SLOWLY W-E IN THE WAKE OF SECONDARY SHRTWV AND LLVL FLOW BECOMES MORE ACYC. LIKELY POPS SEEM JUSTIFIED ALL DAY OVER THE E. PER NCEP PREFERENCE...HAVE FOLLOWED THE SLOWER UKMET/NAM MODELS FOR THU NGT/FRI PD. 12Z GFS WOULD BRING WAD SN CHCS IN SW FLOW AHEAD OF INCOMING SHRTWV INTO THE ENTIRE FA BY LATE THU NGT...BUT SLOWER UKMET/NAM HINT SFC RDG AXIS WL BE SLOWER TO SHIFT TO THE E. HOWEVER... INTRODUCED LO CHC POPS EARLIER THAN PREVIOUS FCST OVER WRN LK SUP AS EARLY AS LATE THU NGT AND THEN ACRS THE ENTIRE FA ON FRI TO ACCOUNT FOR FASTER TREND OF 12Z ECMWF/00Z GFS REFCST ENSEMBLE MEAN. TENDED TOWARD THE LWR NAM MOS AND/OR GOING FCST LO/HI TEMPS THU NGT/FRI TO ACCOUNT FOR MORE PERSISTENT LLVL COLD AIR/SLOWER RDG. IN THE MEDIUM/EXTENDED RANGE...NEGATIVE NAO/POSITIVE PNA PATTERN WL MAINTAIN ITS ICY GRIP ON ERN NAMERICA WITH NW FLOW ALF BTWN HI AMPLITUDE RDG OVER WRN NAMERICA AND DEEP TROF OVER THE E ADVECTING ARCTIC AIR INTO THE AREA. TIMING/IMPACT OF CLIPPER SHRTWVS EMBEDDED WITHIN THIS FLOW WL BE THE MAIN CHALLENGE IN THIS PD. THE FIRST OF THESE SHRTWVS WL BE A SGNFT INFLUENCE ON THE WX OVER UPR MI THIS WEEKEND. OPERATIONAL MODELS SHOW SHRTWV REACHING NRN MANITOBA/FAR NW ONTARIO BY 00Z SAT AND THEN SPLITING WITH ONE PIECE MOVING TO NEAR JAMES BAY AND ANOTHER TO NEAR WRN LK SUP BY 00Z SUN. THE ECMWF HAS BEEN THE MOST CONSISTENT WITH THE DETAILS OF THIS SYS...AND NCEP HAS CLOSELY FOLLOWED THE 00Z ECMWF FCST. 12Z GFS HAS TRENDED FASTER AGAIN AFT 06Z RUN HAD SLOWED DOWN FCST ARRIVAL OF THE SYS. AS MENTIONED ABV...FOLLOWED THE SLOWER 12Z UKMET AND NAM/00Z ECMWF FOR TIMING OF PCPN ASSOCIATED WITH THIS SYS PER NCEP PREFERENCE. THE 00Z ECMWF SHOWS A DRY SFC TROF PASSAGE ON FRI NGT (H7 RH BLO 30 PCT) AS INITIAL SHRTWV/SFC LO MOVES ACRS ONTARIO. DEEPER MSTR EVIDENT ON SAT AS SECOND SHRTWV DIGS INTO THE UPR GRT LKS. GOING FCST SCHC POPS FOR FRI NGT TRANSITIONING TO HIER CHC POPS ON SAT ESPECIALLY NR LK SUP APPEARS ON TRACK. ECMWF AND OTHER OPS MODELS HAVE BACKED OFF ON EXTENT OF COLD AIR FCST TO DROP INTO THE UPR LKS IN THE WAKE OF THIS CLIPPER COMPLEX...BUT INCOMING AIRMASS (H85 TEMPS ARND -18C) ARE STILL LO ENUF TO JUSTIFY LIKELY POPS FOR LES SAT NGT WHEN FA FCST TO FALL ON CYC SIDE OF H5 VORT TRACK. LOOK FOR THE LES TO WIND DOWN ON SUN WITH APRCH OF RISING HGTS/SFC HI PRES RDG AXIS IN ADVANCE OF NEXT CLIPPER SHRTWV THAT WL IMPACT THE FA ON MON. THEN A CHANCE OF LES IN THE WAKE OF THIS SYS ON TUE. COORDINATED WITH DLH. && .MQT WATCHES/WARNINGS/ADVISORIES...NONE && $$ KC mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 345 AM EST TUE JAN 23 2007 .SYNOPSIS... 08Z WATER VAPOR LOOP AND RUC 500MB HEIGHT ANALYSIS SHOWED UPPER LEVEL TROUGHING COVERING MUCH OF EASTERN CANADA AND THE WESTERN GREAT LAKES WHILE RIDGING COVERED MOST OF WESTERN NORTH AMERICA. THE MOST SIGNIFICANT FEATURE IN THE SHORT TERM WITH THE TROUGH IS A SHRTWV DIVING SE INTO NORTHERN MINNESOTA AND WESTERN LAKE SUPERIOR...ALONG WITH AN 80 KT JET STREAK AROUND 300MB LOCATED IMMEDIATELY ON THE SW SIDE OF THE SHRTWV. UPPER DIVERGENCE IN THE LEFT EXIT REGION OF THE JET STREAK ALONG WITH DPVA AHEAD OF THE SHRTWV HAS HELPED PRODUCE A LITTLE SYNOPTIC SNOW FROM NE MINNESOTA TO THE NORTH HALF OF UPPER MICHIGAN. MUCH OF THIS SNOW IS ALONG AND BEHIND A 1004 MB SURFACE TROUGH...STRETCHING FROM NE MINNESOTA TO JUST N OF THE KEWEENAW PENINSULA...BECAUSE OF DRIER AIR AHEAD OF IT SEEN ON THE 00Z INL AND GRB SOUNDINGS. HOWEVER...THE AIR IS MORE MOIST AND COLDER BEHIND THE TROUGH...NOTED BY THE CWPL SOUNDING SHOWING SATURATED CONDITIONS UP TO 400MB AND 850MB TEMPS AROUND -12C. ALSO TO NOTE IS AN AREA OF 1MB/HR PRESSURE RISES ACROSS NW ONTARIO...WHICH MAY HELP IN INCREASING WINDS TODAY. ALSO TO NOTE IS AN AREA OF BELOW ZERO DEWPOINTS MOVING SE THROUGH NW ONTARIO... SUGGESTING THAT THE CWPL SOUNDING MAY HAVE BEEN ON THE EDGE OF DEEPER MOISTURE. THE 00Z CYQD SOUNDING IN CENTRAL MANITOBA WAS QUITE A BIT DRIER. THIS DRY AIR IS ASSOCIATED WITH A 1020MB HIGH DROPPING SOUTH THROUGH MANITOBA. .DISCUSSION... TODAY...AS THE UPPER LEVEL JET STREAK...SHRTWV AND SURFACE TROUGH CONTINUE MAKING THEIR WAY SE DUE TO THE NW FLOW ALOFT...SYNOPTIC LIGHT SNOW/FLURRIES WILL CONTINUE TO MOVE ACROSS THE CWA THIS MORNING. THE MORE SIGNIFICANT IMPACTS FROM THESE FEATURES IS A CONVERGENT BAND OF LAKE EFFECT SNOW THAT WILL LIKELY BE LOCATED ON THE SURFACE TROUGH (AT THE TIME OF THIS ISSUANCE...IT WOULD BE LOCATED BETWEEN ISLE ROYALE AND THE KEWEENAW PENINSULA). THE PROGGED LOW LEVEL WIND FLOW WOULD SUGGEST MAINLY THE KEWEENAW AND AREAS EAST OF MARQUETTE TO BE MOST IMPACTED. GIVEN THAT INVERSION HEIGHTS ARE AROUND 800MB WHEN THIS BAND MOVES THROUGH AND THE DENDRITIC SNOW GROWTH LAYER IS SATURATED WITH SOME VERTICAL MOTION...A COUPLE OF INCHES SHOULD ACCUMULATE WITH THE BAND OF SNOW. AFTER THE PASSAGE OF THE TROUGH...NW WINDS WILL INCREASE DUE TO A COMBINATION OF THE PRESSURE RISES AND COLD AIR ADVECTION. BY 21Z...THE NAM AND GFS SHOW 850MB TEMPS FALLING TO -14C TO -18C (COLDEST OVER EASTERN LAKE SUPERIOR). THEREFORE MULTI-PARALLEL LES BANDS ARE EXPECTED TO SETUP BEHIND THE TROUGH. HOWEVER...MUCH OF THIS LAKE EFFECT SHOULD BE LIGHT AS SUBSIDENCE AND DRY AIR ADVECTION IN THE WAKE OF THE SHRTWV PUSH INVERSIONS DOWN TO 850MB OR LOWER. IN FACT...THE NAM SHOWS THE AVERAGE 800-700MB RH DROPPING TO NEAR 5 PERCENT BY 00Z. GIVEN THE COLD AIR ADVECTION...HIGH TEMPERATURES ARE EXPECTED IN MOST LOCATIONS THIS MORNING. GUIDANCE READINGS SEEM REASONABLE. TONIGHT...NAM/GFS SHOW SOME WEAK RIDGING DEVELOPING DURING THE NIGHT AS A RESULT OF ANOTHER SHRTWV CURRENTLY OVER THE NW TERRITORIES MOVING S TO FAR WESTERN ONTARIO BY 12Z. THIS RIDGING...COMBINED WITH THE DRY MID LEVEL AIR MENTIONED IN THE TODAY DISCUSSION...WILL PREVENT ANY SYNOPTIC PCPN. AS FOR LAKE EFFECT SNOW CHANCES...850MB TEMPS FALL TO -16C WEST TO -20C EAST BY 12Z...SO LES WILL CONTINUE. HOWEVER...MODELS SUGGEST INCREASING WIND SHEAR AS THE SURFACE WIND FLOW OVER LAKE SUPERIOR TURNS MORE DUE NORTH COMPARED TO NORTHWEST FLOW AT 850MB. WITH DRY AIR CONTINUING TO MOVE ACROSS LAKE SUPERIOR...ALONG WITH LOW INVERSIONS...NOT EXPECTING MUCH LAKE EFFECT ACCUMULATION. TEMPERATURES ARE A LITTLE TRICKY AS MODELS SUGGEST LIGHT NW SURFACE WINDS IN THE INTERIOR. WITH THE DRY AIR ADVECTION AND PERHAPS A FEW LAKE EFFECT CLOUDS PASSING BY...THE INTERIOR MAY GET QUITE CHILLY. HAVE WENT TOWARD THE LOWER END OF GUIDANCE BECAUSE OF THIS. ELSEWHERE...LAKE SUPERIOR AIR SHOULD KEEP THE REST OF THE AREA WARMER. WED...THERE ARE A FEW MODEL DIFFERENCES REGARDING WHAT OCCURS WITH THE SHRTWV EXPECTED OVER FAR WESTERN ONTARIO AT 12Z. THE GFS DIGS THIS SHRTWV TOWARDS THE SOUTHERN END OF LAKE MICHIGAN BY 00Z WHEREAS THE UKMET/NAM TAKE IT INTO UPPER MICHIGAN. THE CANADIAN APPEARS TO BE A COMPROMISE. DESPITE THE DIFFERENCES...ALL MODELS SUGGEST VERY LITTLE IN THE WAY OF MID LEVEL MOISTURE...SO NO SYNOPTIC PCPN IS EXPECTED FROM THE SHRTWV. HOWEVER...THE DIFFERENCES DO IMPACT THE SURFACE WIND FIELD...WITH THE EXTREME CASE OF THE UKMET SHOWING A 1015MB LOW OVER MARQUETTE AT 00Z. PREFER TO STAY TOWARD THE MAJORITY AND PREVIOUS FORECAST CONSENSUS OF A SURFACE TROUGH WHICH EXTENDS FROM CENTRAL LAKE SUPERIOR TO DETROIT THROUGH THE DAY. WITH 850MB TEMPS REMAINING CHILLY (-18 TO -20C)...LAKE EFFECT SHOULD CONTINUE. THERE IS SOME CONCERN OF A CONVERGENT LES BAND LOCATED ALONG THE SURFACE TROUGH (SEE 00Z RUC 13)...HOWEVER THE LACK OF MOISTURE AND LOW INVERSIONS SHOULD KEEP THE INTENSITY OF THE BAND DOWN. GIVEN COOL NIGHT TIME LOWS AND THE COLD AIR ADVECTION...HIGHS WILL END UP BELOW NORMAL. AGAIN STAYED TOWARD THE LOWER END OF GUIDANCE. WED NIGHT AND THU...NO MATTER WHERE THE SHRTWV IS AT 00Z THU...ALL MODELS HAVE IT DIGGING SOUTHWARD INTO THE OHIO VALLEY ON THU. THIS SHRTWV HELPS LOCK IN THE UPPER TROUGH OVER THE EASTERN GREAT LAKES...ALONG WITH MAINTAIN CHILLY 850MB TEMPS OVER THE CWA. THE 00Z ECMWF SHOWS 850MB TEMPS AT 00Z FRI RANGING FROM -18C WEST TO -22C EAST. GIVEN THE COLD AIR...LAKE EFFECT SNOW SHOWERS WILL CONTINUE...THOUGH AS A SURFACE HIGH PRESSURE RIDGE WORKS IN FROM THE WEST ON THU...THE LAKE EFFECT COVERAGE IS EXPECTED TO DIMINISH. HOWEVER...IT STILL DOES NOT LOOK LIKE ANY SIGNIFICANT LAKE EFFECT SNOW DUE TO DRY AIR ADVECTION AND SUBSIDENCE BEHIND WEDNESDAYS SHRTWV. GIVEN THE CHILLY 850MB TEMPS...HAVE CONTINUED TO STAY ON THE LOWER END OF GUIDANCE WHICH WAS SIMILAR TO THE PREVIOUS FORECAST. THU NIGHT AND FRI...MODELS CONTINUE TO PROG A STRONG CLIPPER MOVING FROM THE YUKON AT 12Z THU DOWN TOWARDS THE WESTERN GREAT LAKES REGION. THERE ARE SOME TIMING DIFFERENCES ON WHEN IT REACHES THE AREA...WITH THE UKMET CONSIDERABLY SLOWER THAN ALL THE OTHER MODELS. THIS APPEARS TO BE RELATED WITH THE TIMING OF HOW LONG THE EASTERN TROUGH STAYS IN PLACE. HPC PREFERS A SLOWER TIMING...SIMILAR TO THE 00Z ECMWF...WHICH MAKES SENSE GIVEN THAT RIGHT NOW A VERY STRONG RIDGE EXISTS OVER THE NORTH ATLANTIC. HOWEVER...THE UKMET MIGHT BE TOO SLOW. ONLY ADJUSTMENT THAT WAS NECESSARY TO THE GRIDS FOR THIS SCENARIO IS TO PUT IN SOME SLIGHT CHANCE POPS FOR SNOW OVER THE WEST HALF OF THE CWA FRI AFTERNOON...SINCE THE ECMWF SHOWS A DECENT LOW LEVEL JET ALONG WITH SATURATED CONDITIONS AT 850MB AT 00Z SAT. ALSO...HAVE LOWERED TEMPS SLIGHTLY THU NIGHT IN THE INTERIOR AS THE SURFACE RIDGE AXIS IS PROGGED TO BE OVERHEAD AT 06Z FRI. ACTUAL LOWS MAY EVEN BE COLDER...BUT THERE IS SOME CONCERN ABOUT WHEN HIGH CLOUDS ASSOCIATED WITH THE CLIPPER MOVE IN. EXTENDED...LATEST 00Z ECMWF HAS BACKED OFF...QUITE CONSIDERABLY...ON THE AMOUNT OF COLD AIR COMING IN BEHIND THE FRI CLIPPER...NOW ONLY SHOWING AROUND -18C. EVEN THE GFS...WHICH HAS A COLDER BIAS OUT IN THE EXTENDED TIME PERIOD...ONLY HAS -22C. NOW IT APPEARS THE COLDER AIR MAY WAIT UNTIL ANOTHER CLIPPER MOVES THROUGH MON INTO TUE. && .MQT WATCHES/WARNINGS/ADVISORIES...NONE && $$ AJ mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MARQUETTE MI 335 PM EST MON JAN 22 2007 .DISCUSSION... 12Z ROABS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW NRN BRANCH NW FLOW ALF OVER THE UPR GRT LKS BTWN RDG OVER THE NRN ROCKIES/SW CAN AND GENERAL TROFFING IN SE CAN. DEEPER MSTR CONFINED TO THE SRN CONUS WITHIN THE SRN BRANCH FLOW THERE. FA CURRENTLY UNDER THE INFLUENCE OF WEAK SFC-H7 RDG NOSING INTO THE UPR GRT LKS. ALTHOUGH THERE HAVE BEEN SOME FLURRIES/-SN ARND IN ASSOCIATION WITH DEPARTING WEAK TROF NOW OVER ERN LK SUP AS WELL AS SOME SFC-H8 MSTR SHOWN ON THE 12Z APX/GRB RAOBS AND 16Z TAMDAR SDNG FM SAW...WHAT LTL SN THAT IS FALLING APPEARS TO BE DIMINISHING/ENDING W-E AS DRIER AIR SHOWN ON THE 12Z INL SDNG PUSHES INTO THE UPR GRT LKS. 12Z PWAT AT INL ONLY 0.16 INCH. NEXT SHRTWV OF CONCERN NOW MOVING INTO CNTRL MANITOBA. PCPN IN ADVANCE OF THIS FEATURE IS QUITE LIMITED BY DRY AIR SHOWN ON THE 12Z INL/BIS/YQD SDNGS DESPITE MODEST ISENTROPIC LIFT/PRES FALLS IN THE SW FLOW AHEAD OF SHRTWV. MAIN FCST CONCERNS THE NEXT FEW DAYS REVOLVE ARND TIMING/IMPACT OF UPSTREAM SHRTWV DROPPING INTO THE UPR GRT LKS IN NW FLOW ALF. FOR TNGT...GOOD AGREEMENT AMONG NAM/GFS/CNDN MODELS SHOWING SHRTWV NOW OVER MANITOBA REACHING CNTRL UPR MI BY 12Z TUE. GFS SHOWS AREA OF H85-5 QVECTOR CNVGC/DPVA MOVING INTO THE FA OVERNGT WHILE ISENTROPIC LIFT APPEARS TO WEAKEN. CONSIDERING DRY AIR UPSTREAM AND MINIMAL MOS POPS...PREFER THE DRIER LOOK OF THE NAM FCST SDNGS. HAVE OPTED TO CARRY CHC POPS ONLY ACRS THE NRN TIER ON CYC SIDE OF H5 VORT TRACK WITH JUST FLURRIES ALG THE WI BORDER/SCNTRL. HIEST POP TO LIKELY OVER THE KEWEENAW...BUT AOB 50 ELSEWHERE. GIVEN OBSVD LO MIN TEMPS UPSTREAM THIS MRNG AND RELATIVELY DRY AIR...WL TEND TOWARD THE LOWER ETA/NGM MOS GUIDANCE FOR MIN TEMPS. EXPECT LES TO DVLP ON TUE DOWNWIND OF LK SUP IN FCST NNW FLOW BEHIND SHRTWV AS H85 TEMPS AS LO AS -15C TO -17C ADVECT INTO THE NRN TIER ZNS BY 00Z WED. WL CARRY LIKELY POPS NR LK SUP AND JUST A CHC OF -SHSN/FLURRIES FARTHER INLAND. INCOMING AIRMASS APPEARS TO BE RATHER DRY WITH INVRN LWRG TO ARND H85 DURING THE AFTN UNDER H85-5 QVECTOR DVGC/DNVA/SUBSIDENCE...SO EXPECT SUB ADVY ACCUMULATIONS. EXPECT HI TEMPS RELATIVELY EARLY IN THE DAY BEFORE INFUSION OF COLDER AIR CAUSES TEMPS REMAIN NEARLY STEADY IN THE AFTN. LES MODERATED BY LOW INVRN HGT/DRY AIR/LARGER SCALE ACYC FLOW/LWRG INVRN HGT WL CONTINUE NR LK SUP TUE NGT. OVER THE INTERIOR...EXPECT TEMPS TO FALL BLO MOS GUIDANCE AWAY FM LK MODERATION WITH DIMINISHING WINDS/APRCH OF RDG AXIS/PWAT ARND 0.1 INCH. NEXT CLIPPER SHRTWV PROGGED TO DIG INTO THE UPR LKS ON WED...WITH FAIRLY VIGOROUS DPVA/H85-5 QVECTOR CNVGC CONTIBUTING TO 12Z-24Z H5 HGT FALLS UP TO 60M. BUT DEEPER MSTR FCST TO REMAIN LOCKED UP WITH SRN BRANCH AND QUITE LIMITED THIS FAR N (GFS FCST PWAT AOB 0.2 INCH). SO THINK ANY SYNOPTIC SN WL BE UNDER AN INCH...WITH THE HIER POPS CLOSE TO LK SUP WHERE OPPORTUNITY FOR ADDITIONAL LK MOISTENING WL BE THERE. ARRIVAL OF H85 TEMPS AOB -20C IN THE WAKE OF THIS SYS WL CRANK UP LES MACHINE WED AFTN/WED NGT...BUT TEMPS MAY BE TOO LO FOR OPTIMUM SN GROWTH/SGFNT ACCUMULATIONS DESPITE RELATIVELY HI POPS IN FVRD AREAS NR LK SUP FOR NNW FLOW. CYC NNE FLOW IN WAKE OF CLIPPER SHRTWV WL BEGIN TO WEAKEN ON THU UNDER SLOWLY BLDG UPR HGTS/APRCHG ARCTIC HI PRES CENTER. 12Z GFS HAS TRENDED MUCH FASTER THAN PREVIOUS RUNS/OTHER OPS MODELS/00Z GFS REFCST ENSEMBLE MEAN...SO REJECTED ITS SOLN FOR TIMING OF SHRTWV AFT THU. WL MAINTAIN LIKELY POPS NR LK SUP THRU THE DAY PER 12Z ECMWF... THEN DIMINISH POPS THU NGT WITH APRCH OF SFC RDG AXIS. EXPECT A VERY COLD NGT WITH TEMPS BLO MOS GUIDANCE OVER THE WCNTRL INTERIOR WITH LGT WINDS/PCLDY SKIES. UPR RDGING WL DOMINATE ON FRI...AND ANY LINGERING SHSN WL END EARLY OVER THE E AS LLVL FLOW FCST TO TURN TO THE SW AHEAD OF NEXT SHRTWV DROPPING THRU SCNTRL CAN. THIS SYS FCST TO IMPACT THE FA EARLY THIS COMING WEEKEND WITH ONE OF COLDEST AIRMASSES OF THE SEASON FOLLOWING LATER IN THE WEEKEND (ECMWF FCST H85 TEMPS TO -22C...GFS FCST TO -26C). ALTHOUGH THE AIRMASS APPEARS TO BE TOO DRY TO SUPPORT POPS AHEAD OF THE INITIAL COLD FROPA FRI NGT...EXPECT INCRSG POPS ON SAT WITH ARRIVAL OF UPR TROF/FALLING HGTS. LES WL BE AN ISSUE ON SAT NGT INTO SUN NGT AS THE COLDER AIR POURS ACRS LK SUP WITH BLUSTERY NNW WIND. THEN EXPECT A MORE TRANQUIL DAY ON MON WITH SFC RDG MOVING ACRS THE AREA AS HGTS RECOVER IN ADVANCE OF ANOTHER CLIPPER SHRTWV. BUT TIMING OF THIS SYS AS WELL AS POTENTIAL FOR LINGERING LES WARRANT LO CHC POPS THE ENTIRE DAY. COORDINATED WITH APX/GRB/DLH. && .MQT WATCHES/WARNINGS/ADVISORIES...NONE && $$ KC mi AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE TWIN CITIES/CHANHASSEN MN 243 PM CST TUE JAN 23 2007 .DISCUSSION... FORECAST CHALLENGES ARE SNOW SHOWERS TONIGHT FOLLOWED BY TEMPS THIS WEEKEND AS COLDER AIR IS ON THE WAY. WEAK LOW OVER SOUTHWEST MANITOBA MOVING SOUTHEAST UNDERNEATH UPPER LEVEL JET AND MID LEVEL BAROCLINIC ZONE. WEAK SFC RIDGE ACROSS WRN MN AHEAD OF THE SYSTEM. CURRENT SATELLITE AND OBSERVATIONAL TRENDS FROM NORTH DAKOTA INDICATE SOME VERTICAL ENHANCEMENT AND COOLING IN THE CLOUDS WITH LIGHT SNOW AT THE SURFACE. 40KM RUC AND 12KM NAM MODELS BOTH BRING MOIST UPGLIDE ON THE 285K SURFACE ACROSS WRN MN THIS EVE AND INTO ERN AND SRN MN OVERNIGHT. SO CONTINUE SNOW SHOWER CHANCES. RUC AND NAM PROGGED SOUNDINGS NEAR DAWN FROM THE I-90 CORRIDOR AREA KEEP THE SATURATED PORTION OF THE COLUMN ABOVE -10C...IMPLYING MAINLY SUPERCOOLED WATER DROPLETS. BUT WITH COLD AIR ADVECTION THROUGH THE COLUMN AND SUPPRESSION BEGINNING ALOFT ANY PRECIP UNDER THE LOW CLOUDS LIKELY TO END BEFORE ANY TRANSITION. TEMPS TONIGHT WILL BE COOLEST IN WRN WI WHERE SURFACE RIDGE WILL BE ATOP AND SKIES WILL BEGIN MAINLY CLEAR. COLD AIR ADVECTION UNDER LOW CLOUDS WILL BE THE RULE WEDS MORNING AND CONTINUE INTO THE AFTERNOON IN WRN WI. SO CONTINUE TO UNDERCUT GUIDANCE ON TEMPS. A FEW FLURRIES MAY SHAKE OUT AS WELL. BEYOND THAT TIME WARM AIR ADVECTION ENSUES THURS AND IN EARNEST THURS NIGHT. HAVE GONE WELL ABOVE GUIDANCE ON TEMPS. NAM AND GFS CONTINUE TO LOCK DOWN FRIDAY AFTERNOON AS COLD FRONTAL PASSAGE TIME. AHEAD OF THIS SOME PLACES LIKELY TO HIT OR EVEN TOP FREEZING ON FRI. AFTERWORDS THE COLD AIR FLOODS IN ESPECIALLY ON SATURDAY NIGHT AS ARCTIC FRONT PASSES AND MID TO UPPER LEVEL FLOW TURNS STRAIGHT FROM THE YUKON. 12Z GFS ENSEMBLE AND OPERATIONAL MODELS ARE MORE EAST WITH POLAR VORTEX AND NOT AS DEEP...BUT NCEP MEDIUM RANGE ENSEMBLE H8 TEMPS STILL AT ONE TO TWO NORMALIZED ANOMALIES BELOW NORMAL SO EXPECT BELOW NORMAL SFC TEMPS WITH SUBZERO VALUES IN MANY PLACES AT NIGHTS BEGINNING SAT NIGHT. BELOW NORMAL TEMPS LIKELY TO LAST INTO THE MIDDLE OF NEXT WEEK WITH ONLY FLURRIES OR LIGHT SNOW SHOWER CHANCES IN THE NORTHWEST FLOW WAVE TRAIN. AT THIS TIME...HAVE OPTED NOT TO MENTION ANY LIGHT SNOW IN FCST UNTIL HIGHER CONFIDENCE CAN BE REACHED. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...NONE. WI...NONE. && $$ MTF mn AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BINGHAMTON NY 1224 PM EST MON JAN 22 2007 .AVIATION /18Z-18Z/... WEAK FLOW PTRN THRU THE PD WILL MAKE FOR LTL CHG IN CONDS. WEAK SHRT WV APPRCHG THE AREA ATTM IS STARTING TO GENERATE A LTL SNOW...AND MAY LWR CIGS AND VSBY FOR A TIME BEFORE 00Z. THEN A SHRT BRK WITH THE SNOW BUT WITH LGT WINDS AND LTL MIXING...WLD NOT XPCT A MAJOR IMPRVMT IN CONDS. AFT 06Z ANOTHER WEAK SHRT WV COMES BY AND MAY AGAIN GENERATE SOME LGT SNOW WITH LWRD CIGS AND VSBYS THRU THE NIGHT. LGT WLY WIND AFT 12Z MAY GENERATE SOME LGT LAKE EFFECT AFT 12Z TUE. && .PREV DISCUSSION... /ISSUED 1012 AM EST MON JAN 22 2007/ SHORT TERM /REST OF TODAY/... LOW LEVEL INSTABILITY COMBINED WITH H5 SHORT WAVE THIS AFTERNOON COULD STILL PRODUCE SNOW SHOWERS PRIMARILY THIS AFTERNOON. CURRENT LOW CHC POPS LOOK REASONABLE. AS WEAK SFC LOW OVER NRN PA MOVES EAST THIS AFTERNOON, FLOW WILL BECOME NORTHWEST WITH WEAK CAA. WITH NRN CWA STILL IN TEENS LOWERED TEMPS A CAT HERE, NO OTHER CHANGES. RRM PREV DISCUSSION... /ISSUED 655 AM EST MON JAN 22 2007/ SHORT TERM /REST OF TODAY/... UL S/WV AND AREA OF LIGHT SNOW HAS MOVED EAST ON SCHEDULE. 06Z MODELS STILL SHOW ANOTHER OPEN WAVE TO CROSS THE AREA TODAY AND THERE IS STILL PLENTY OF RESIDUAL MOISTURE AND SOME INSTABILITY AROUND. A FEW SFC OBS IN UPR MIDWEST SHOW SNOW...BUT AM HARD PRESSED TO FIND IT ON RADAR. THE CHC POPS WE HAD COVERING THE REST OF TODAY LOOK FINE...MAY EVEN BE OVERDONE A TAD SINCE IF ANYTHING DEVELOPS THE ACCUMS WOULD BE VERY LIGHT. KICKED OUT AN UPDATED ZFP/TABULAR FCSTS TO CLEAN OUT THE PRIOR TO SUNRISE EVENT. AVIATION /12Z-12Z/... PLENTY OF RESIDUAL LLVL MOISTURE AROUND THE REGION WITH LIGHT AND VARIABLE FLOW EXPECTED. WEAK SFC LOW PASSES THE AREA THIS AFTERNOON AND SFC FLOW BECOMES NW 5-10 KTS. A BRIEF PERIOD OF VFR IS EXPECTED UNTIL 14Z-16Z THIS MORNING AS SUBSIDENCE BEHIND UL WAVE MIXES THINGS UP. THE REAL LOW CIGS UPSTREAM OVER OH/WRN NY/WRN PA SHOULD MIX OUT A BIT...SO WILL KEEP THINGS MVFR PRETTY MUCH THROUGH THE PERIOD. EXCEPTION COULD BE ITH WHERE A LIGHT NWLY FLOW DEVELOPING THIS AFTERNOON OFF THE LAKE MAY DROP THEM TO IFR AS WE HAVE SEEN UNEXPECTEDLY IN THE PAST. WILL TRY TO BEAT THE ODDS AND STAY AHEAD OF THAT ONE. ANOTHER WEAK UL WAVE PASSES THE AREA THIS AFTERNOON. NOT MUCH PRECIP CURRENTLY ASSOCIATED WITH WAVE...SO CONFIDENCE LOW THAT ANY RESTRICTIVE SNOW WILL OCCUR. LITTLE TO NO IMPROVEMENT AFT 00Z...AND MAY EVEN SEE VSBYS DIP 3-5SM. PREV DISCUSSION... /ISSUED 242 AM EST MON JAN 22 2007/ SHORT TERM /TODAY THROUGH WEDNESDAY/... LIGHT SNOW MOVING INTO WRN NY EARLY THIS MORNING AHEAD OF AN OPEN S/WV TROF. TROF AXIS IS FCST BY GFS/NAM/RUC TO BE JUST EAST OF CNY AT 12Z...SO THIS WILL BE A QUICK HITTING...INSIGNIFICANT SNOWFALL OCCURRING BEFORE THE CLASSIC TODAY PERIOD. DTX REPORTED 0.3 INCHES SNOWFALL AT THE 06Z SYNOPTIC OB...AND THAT SHOULD BE TOP END FOR MOST OF THE BGM FCST AREA EARLY TODAY. HAVE HANDLED THE SNOW AS A LIKELY EVENT 08Z-12Z. THE PIT 00Z SOUNDING WAS CLASSIC FOR FZDZ WITH A MOIST LAYER OF SUBFREEZING AIR BETWEEN 0 TO -10C. WV LOOP SHOWS DRY AIR WORKING IN ALOFT ACROSS NRN PA...KEEPING THE SNOW CRYSTAL GROWTH ZONE DRY. BUF SOUNDING SHOWED MORE MOISTURE ALOFT...AND WE HAVE ONLY SEEN -SN REPORTS UPSTREAM IN NY/ONTARIO WITH FZDZ REPORTS COMING FROM SRN OH/PA. STILL FEEL THERE IS A REMOTE CHC FOR PATCHY FZDZ ACROSS NRN PA EARLY THIS MORNING IN THIS ENVIRONMENT...SO WILL LEAVE IT IN...BUT NO ADVISORY AS PCPN VERY LIGHT. MOST AREAS WILL THEN HAVE A BREAK FROM PRECIP FOR MOST OF THE DAY...ALTHOUGH A SECOND UL WAVE MOVES THROUGH THE BROAD CYCLONIC FLOW DURING THE EARLY AFTERNOON...AND WEAK SFC CONVG ZONE MOVES ACROSS PA. RADARS UPSTREAM SHOW LITTLE IF ANYTHING GOING ON WITH THIS FEATURE...BUT QVECTOR CONVG DOES IMPLY JUST BROAD...WEAK UPWARD MOTION WHEN IT MOVES THROUGH...AND THERE SHOULD BE SOME DESTABILIZATION OF THE LOWER ATMOSPHERE IN PART DUE TO CAA BETWEEN 850-700 MB ON TOP OF THE MOIST BLYR BENEATH. WITH SUCH WEAK LIFT ACROSS THE AREA...ANY PRECIP ACTIVITY AFT 12Z TODAY LOOKS MINIMAL SO WILL THROTTLE BACK FROM PREVIOUS FCST TO JUST A CHC OF SHSN OR FLURRIES. ANY SNOW ACCUMS LIKELY ONLY A DUSTING TO QUARTER INCH AT BEST WITH GRAINY NEEDLE SNOW. A VERY SIMILAR PATTERN CONTINUES THROUGH WEDNESDAY WITH A SERIES OF WEAK WAVES PASSING THROUGH THE AREA EMBEDDED IN THE BROAD CYCLONIC FLOW ALOFT. HARD TO PIN DOWN MUCH DETAIL IN THIS PATTERN BUT FEEL THERE IS SOME CHANCE FOR FLAKES TO FLY AT ANY TIME...WITH DUSTING AMOUNTS OF ACCUMULATION. THE BEST CHANCES WILL BE FROM THE FINGER LAKES TO THE SOUTHERN TUG. FCST SOUNDINGS HERE SHOW A PERSISTENT NWLY FLOW IN THE BLYR WITH COLDER AIR GRDLY SEEPING ACROSS THE AREA. UL WAVES SHOULD BE ABLE TO TAP INTO SOME OF THAT LAKE ONTARIO INDUCED DESTABILIZATION. MEANWHILE...NEPA AND SRN NY MAY SEE FLURRIES...BUT WILL BE FREE OF SIGNIFICANT PRECIP. USED A BLEND OF MAV/FWC TEMPS THROUGH 48 HOURS...ALTHOUGH TRIMMED MAXES A LITTLE ON WEDNESDAY...AND ADJUSTED TREND SLIGHTLY AHEAD OF NORMAL DIURNAL CURVE WITH A COLDER SURGE IN 925-850 MB TEMPS NOTED BY EVENING. LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/... WEAK CLIPPER WILL MOVE THRU REGION WEDNESDAY NIGHT WITH RAPID DEEPENING ONCE SFC LOW MOVES OFF THE EAST COAST. AS THIS SYSTEM BOMBS OFF THE CANADIAN MARITIMES AND EASTERN TROF DEEPENS, COLDEST AIRMASS OF THE WINTER WILL SPILL OVER AREA, THURSDAY NIGHT THROUGH FRIDAY NIGHT. NORTHWEST FLOW THROUGH THIS PERIOD WILL ACTIVATE LAKE ONTARIO WITH SCATTERED SNOW SHOWERS ACROSS MUCH OF CENTRAL NEW YORK. BRIEF UPPER LEVEL AND SFC RIDGING MAY BRING A QUIET PERIOD LATE FRIDAY/FRIDAY NIGHT BEFORE NEXT CLIPPER SYSTEM MOVES ACROSS SOUTHERN CANADA. && .BGM WATCHES/WARNINGS/ADVISORIES... NY...NONE. PA...NONE. && $$ AVIATION...DGM ny AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BINGHAMTON NY 1012 AM EST MON JAN 22 2007 .SHORT TERM /REST OF TODAY/... LOW LEVEL INSTABILITY COMBINED WITH H5 SHORT WAVE THIS AFTERNOON COULD STILL PRODUCE SNOW SHOWERS PRIMARILY THIS AFTERNOON. CURRENT LOW CHC POPS LOOK REASONABLE. AS WEAK SFC LOW OVER NRN PA MOVES EAST THIS AFTERNOON, FLOW WILL BECOME NORTHWEST WITH WEAK CAA. WITH NRN CWA STILL IN TEENS LOWERED TEMPS A CAT HERE, NO OTHER CHANGES. RRM && .PREV DISCUSSION... /ISSUED 655 AM EST MON JAN 22 2007/ SHORT TERM /REST OF TODAY/... UL S/WV AND AREA OF LIGHT SNOW HAS MOVED EAST ON SCHEDULE. 06Z MODELS STILL SHOW ANOTHER OPEN WAVE TO CROSS THE AREA TODAY AND THERE IS STILL PLENTY OF RESIDUAL MOISTURE AND SOME INSTABILITY AROUND. A FEW SFC OBS IN UPR MIDWEST SHOW SNOW...BUT AM HARD PRESSED TO FIND IT ON RADAR. THE CHC POPS WE HAD COVERING THE REST OF TODAY LOOK FINE...MAY EVEN BE OVERDONE A TAD SINCE IF ANYTHING DEVELOPS THE ACCUMS WOULD BE VERY LIGHT. KICKED OUT AN UPDATED ZFP/TABULAR FCSTS TO CLEAN OUT THE PRIOR TO SUNRISE EVENT. AVIATION /12Z-12Z/... PLENTY OF RESIDUAL LLVL MOISTURE AROUND THE REGION WITH LIGHT AND VARIABLE FLOW EXPECTED. WEAK SFC LOW PASSES THE AREA THIS AFTERNOON AND SFC FLOW BECOMES NW 5-10 KTS. A BRIEF PERIOD OF VFR IS EXPECTED UNTIL 14Z-16Z THIS MORNING AS SUBSIDENCE BEHIND UL WAVE MIXES THINGS UP. THE REAL LOW CIGS UPSTREAM OVER OH/WRN NY/WRN PA SHOULD MIX OUT A BIT...SO WILL KEEP THINGS MVFR PRETTY MUCH THROUGH THE PERIOD. EXCEPTION COULD BE ITH WHERE A LIGHT NWLY FLOW DEVELOPING THIS AFTERNOON OFF THE LAKE MAY DROP THEM TO IFR AS WE HAVE SEEN UNEXPECTEDLY IN THE PAST. WILL TRY TO BEAT THE ODDS AND STAY AHEAD OF THAT ONE. ANOTHER WEAK UL WAVE PASSES THE AREA THIS AFTERNOON. NOT MUCH PRECIP CURRENTLY ASSOCIATED WITH WAVE...SO CONFIDENCE LOW THAT ANY RESTRICTIVE SNOW WILL OCCUR. LITTLE TO NO IMPROVEMENT AFT 00Z...AND MAY EVEN SEE VSBYS DIP 3-5SM. PREV DISCUSSION... /ISSUED 242 AM EST MON JAN 22 2007/ SHORT TERM /TODAY THROUGH WEDNESDAY/... LIGHT SNOW MOVING INTO WRN NY EARLY THIS MORNING AHEAD OF AN OPEN S/WV TROF. TROF AXIS IS FCST BY GFS/NAM/RUC TO BE JUST EAST OF CNY AT 12Z...SO THIS WILL BE A QUICK HITTING...INSIGNIFICANT SNOWFALL OCCURRING BEFORE THE CLASSIC TODAY PERIOD. DTX REPORTED 0.3 INCHES SNOWFALL AT THE 06Z SYNOPTIC OB...AND THAT SHOULD BE TOP END FOR MOST OF THE BGM FCST AREA EARLY TODAY. HAVE HANDLED THE SNOW AS A LIKELY EVENT 08Z-12Z. THE PIT 00Z SOUNDING WAS CLASSIC FOR FZDZ WITH A MOIST LAYER OF SUBFREEZING AIR BETWEEN 0 TO -10C. WV LOOP SHOWS DRY AIR WORKING IN ALOFT ACROSS NRN PA...KEEPING THE SNOW CRYSTAL GROWTH ZONE DRY. BUF SOUNDING SHOWED MORE MOISTURE ALOFT...AND WE HAVE ONLY SEEN -SN REPORTS UPSTREAM IN NY/ONTARIO WITH FZDZ REPORTS COMING FROM SRN OH/PA. STILL FEEL THERE IS A REMOTE CHC FOR PATCHY FZDZ ACROSS NRN PA EARLY THIS MORNING IN THIS ENVIRONMENT...SO WILL LEAVE IT IN...BUT NO ADVISORY AS PCPN VERY LIGHT. MOST AREAS WILL THEN HAVE A BREAK FROM PRECIP FOR MOST OF THE DAY...ALTHOUGH A SECOND UL WAVE MOVES THROUGH THE BROAD CYCLONIC FLOW DURING THE EARLY AFTERNOON...AND WEAK SFC CONVG ZONE MOVES ACROSS PA. RADARS UPSTREAM SHOW LITTLE IF ANYTHING GOING ON WITH THIS FEATURE...BUT QVECTOR CONVG DOES IMPLY JUST BROAD...WEAK UPWARD MOTION WHEN IT MOVES THROUGH...AND THERE SHOULD BE SOME DESTABILIZATION OF THE LOWER ATMOSPHERE IN PART DUE TO CAA BETWEEN 850-700 MB ON TOP OF THE MOIST BLYR BENEATH. WITH SUCH WEAK LIFT ACROSS THE AREA...ANY PRECIP ACTIVITY AFT 12Z TODAY LOOKS MINIMAL SO WILL THROTTLE BACK FROM PREVIOUS FCST TO JUST A CHC OF SHSN OR FLURRIES. ANY SNOW ACCUMS LIKELY ONLY A DUSTING TO QUARTER INCH AT BEST WITH GRAINY NEEDLE SNOW. A VERY SIMILAR PATTERN CONTINUES THROUGH WEDNESDAY WITH A SERIES OF WEAK WAVES PASSING THROUGH THE AREA EMBEDDED IN THE BROAD CYCLONIC FLOW ALOFT. HARD TO PIN DOWN MUCH DETAIL IN THIS PATTERN BUT FEEL THERE IS SOME CHANCE FOR FLAKES TO FLY AT ANY TIME...WITH DUSTING AMOUNTS OF ACCUMULATION. THE BEST CHANCES WILL BE FROM THE FINGER LAKES TO THE SOUTHERN TUG. FCST SOUNDINGS HERE SHOW A PERSISTENT NWLY FLOW IN THE BLYR WITH COLDER AIR GRDLY SEEPING ACROSS THE AREA. UL WAVES SHOULD BE ABLE TO TAP INTO SOME OF THAT LAKE ONTARIO INDUCED DESTABILIZATION. MEANWHILE...NEPA AND SRN NY MAY SEE FLURRIES...BUT WILL BE FREE OF SIGNIFICANT PRECIP. USED A BLEND OF MAV/FWC TEMPS THROUGH 48 HOURS...ALTHOUGH TRIMMED MAXES A LITTLE ON WEDNESDAY...AND ADJUSTED TREND SLIGHTLY AHEAD OF NORMAL DIURNAL CURVE WITH A COLDER SURGE IN 925-850 MB TEMPS NOTED BY EVENING. LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/... WEAK CLIPPER WILL MOVE THRU REGION WEDNESDAY NIGHT WITH RAPID DEEPENING ONCE SFC LOW MOVES OFF THE EAST COAST. AS THIS SYSTEM BOMBS OFF THE CANADIAN MARITIMES AND EASTERN TROF DEEPENS, COLDEST AIRMASS OF THE WINTER WILL SPILL OVER AREA, THURSDAY NIGHT THROUGH FRIDAY NIGHT. NORTHWEST FLOW THROUGH THIS PERIOD WILL ACTIVATE LAKE ONTARIO WITH SCATTERED SNOW SHOWERS ACROSS MUCH OF CENTRAL NEW YORK. BRIEF UPPER LEVEL AND SFC RIDGING MAY BRING A QUIET PERIOD LATE FRIDAY/FRIDAY NIGHT BEFORE NEXT CLIPPER SYSTEM MOVES ACROSS SOUTHERN CANADA. && .BGM WATCHES/WARNINGS/ADVISORIES... NY...NONE. PA...NONE. && $$ ny AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE BINGHAMTON NY 655 AM EST MON JAN 22 2007 .SHORT TERM /REST OF TODAY/... UL S/WV AND AREA OF LIGHT SNOW HAS MOVED EAST ON SCHEDULE. 06Z MODELS STILL SHOW ANOTHER OPEN WAVE TO CROSS THE AREA TODAY AND THERE IS STILL PLENTY OF RESIDUAL MOISTURE AND SOME INSTABILITY AROUND. A FEW SFC OBS IN UPR MIDWEST SHOW SNOW...BUT AM HARD PRESSED TO FIND IT ON RADAR. THE CHC POPS WE HAD COVERING THE REST OF TODAY LOOK FINE...MAY EVEN BE OVERDONE A TAD SINCE IF ANYTHING DEVELOPS THE ACCUMS WOULD BE VERY LIGHT. KICKED OUT AN UPDATED ZFP/TABULAR FCSTS TO CLEAN OUT THE PRIOR TO SUNRISE EVENT. && .AVIATION /12Z-12Z/... PLENTY OF RESIDUAL LLVL MOISTURE AROUND THE REGION WITH LIGHT AND VARIABLE FLOW EXPECTED. WEAK SFC LOW PASSES THE AREA THIS AFTERNOON AND SFC FLOW BECOMES NW 5-10 KTS. A BRIEF PERIOD OF VFR IS EXPECTED UNTIL 14Z-16Z THIS MORNING AS SUBSIDENCE BEHIND UL WAVE MIXES THINGS UP. THE REAL LOW CIGS UPSTREAM OVER OH/WRN NY/WRN PA SHOULD MIX OUT A BIT...SO WILL KEEP THINGS MVFR PRETTY MUCH THROUGH THE PERIOD. EXCEPTION COULD BE ITH WHERE A LIGHT NWLY FLOW DEVELOPING THIS AFTERNOON OFF THE LAKE MAY DROP THEM TO IFR AS WE HAVE SEEN UNEXPECTEDLY IN THE PAST. WILL TRY TO BEAT THE ODDS AND STAY AHEAD OF THAT ONE. ANOTHER WEAK UL WAVE PASSES THE AREA THIS AFTERNOON. NOT MUCH PRECIP CURRENTLY ASSOCIATED WITH WAVE...SO CONFIDENCE LOW THAT ANY RESTRICTIVE SNOW WILL OCCUR. LITTLE TO NO IMPROVEMENT AFT 00Z...AND MAY EVEN SEE VSBYS DIP 3-5SM. && .PREV DISCUSSION... /ISSUED 242 AM EST MON JAN 22 2007/ SHORT TERM /TODAY THROUGH WEDNESDAY/... LIGHT SNOW MOVING INTO WRN NY EARLY THIS MORNING AHEAD OF AN OPEN S/WV TROF. TROF AXIS IS FCST BY GFS/NAM/RUC TO BE JUST EAST OF CNY AT 12Z...SO THIS WILL BE A QUICK HITTING...INSIGNIFICANT SNOWFALL OCCURRING BEFORE THE CLASSIC TODAY PERIOD. DTX REPORTED 0.3 INCHES SNOWFALL AT THE 06Z SYNOPTIC OB...AND THAT SHOULD BE TOP END FOR MOST OF THE BGM FCST AREA EARLY TODAY. HAVE HANDLED THE SNOW AS A LIKELY EVENT 08Z-12Z. THE PIT 00Z SOUNDING WAS CLASSIC FOR FZDZ WITH A MOIST LAYER OF SUBFREEZING AIR BETWEEN 0 TO -10C. WV LOOP SHOWS DRY AIR WORKING IN ALOFT ACROSS NRN PA...KEEPING THE SNOW CRYSTAL GROWTH ZONE DRY. BUF SOUNDING SHOWED MORE MOISTURE ALOFT...AND WE HAVE ONLY SEEN -SN REPORTS UPSTREAM IN NY/ONTARIO WITH FZDZ REPORTS COMING FROM SRN OH/PA. STILL FEEL THERE IS A REMOTE CHC FOR PATCHY FZDZ ACROSS NRN PA EARLY THIS MORNING IN THIS ENVIRONMENT...SO WILL LEAVE IT IN...BUT NO ADVISORY AS PCPN VERY LIGHT. MOST AREAS WILL THEN HAVE A BREAK FROM PRECIP FOR MOST OF THE DAY...ALTHOUGH A SECOND UL WAVE MOVES THROUGH THE BROAD CYCLONIC FLOW DURING THE EARLY AFTERNOON...AND WEAK SFC CONVG ZONE MOVES ACROSS PA. RADARS UPSTREAM SHOW LITTLE IF ANYTHING GOING ON WITH THIS FEATURE...BUT QVECTOR CONVG DOES IMPLY JUST BROAD...WEAK UPWARD MOTION WHEN IT MOVES THROUGH...AND THERE SHOULD BE SOME DESTABILIZATION OF THE LOWER ATMOSPHERE IN PART DUE TO CAA BETWEEN 850-700 MB ON TOP OF THE MOIST BLYR BENEATH. WITH SUCH WEAK LIFT ACROSS THE AREA...ANY PRECIP ACTIVITY AFT 12Z TODAY LOOKS MINIMAL SO WILL THROTTLE BACK FROM PREVIOUS FCST TO JUST A CHC OF SHSN OR FLURRIES. ANY SNOW ACCUMS LIKELY ONLY A DUSTING TO QUARTER INCH AT BEST WITH GRAINY NEEDLE SNOW. A VERY SIMILAR PATTERN CONTINUES THROUGH WEDNESDAY WITH A SERIES OF WEAK WAVES PASSING THROUGH THE AREA EMBEDDED IN THE BROAD CYCLONIC FLOW ALOFT. HARD TO PIN DOWN MUCH DETAIL IN THIS PATTERN BUT FEEL THERE IS SOME CHANCE FOR FLAKES TO FLY AT ANY TIME...WITH DUSTING AMOUNTS OF ACCUMULATION. THE BEST CHANCES WILL BE FROM THE FINGER LAKES TO THE SOUTHERN TUG. FCST SOUNDINGS HERE SHOW A PERSISTENT NWLY FLOW IN THE BLYR WITH COLDER AIR GRDLY SEEPING ACROSS THE AREA. UL WAVES SHOULD BE ABLE TO TAP INTO SOME OF THAT LAKE ONTARIO INDUCED DESTABILIZATION. MEANWHILE...NEPA AND SRN NY MAY SEE FLURRIES...BUT WILL BE FREE OF SIGNIFICANT PRECIP. USED A BLEND OF MAV/FWC TEMPS THROUGH 48 HOURS...ALTHOUGH TRIMMED MAXES A LITTLE ON WEDNESDAY...AND ADJUSTED TREND SLIGHTLY AHEAD OF NORMAL DIURNAL CURVE WITH A COLDER SURGE IN 925-850 MB TEMPS NOTED BY EVENING. LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/... WEAK CLIPPER WILL MOVE THRU REGION WEDNESDAY NIGHT WITH RAPID DEEPENING ONCE SFC LOW MOVES OFF THE EAST COAST. AS THIS SYSTEM BOMBS OFF THE CANADIAN MARITIMES AND EASTERN TROF DEEPENS, COLDEST AIRMASS OF THE WINTER WILL SPILL OVER AREA, THURSDAY NIGHT THROUGH FRIDAY NIGHT. NORTHWEST FLOW THROUGH THIS PERIOD WILL ACTIVATE LAKE ONTARIO WITH SCATTERED SNOW SHOWERS ACROSS MUCH OF CENTRAL NEW YORK. BRIEF UPPER LEVEL AND SFC RIDGING MAY BRING A QUIET PERIOD LATE FRIDAY/FRIDAY NIGHT BEFORE NEXT CLIPPER SYSTEM MOVES ACROSS SOUTHERN CANADA. AVIATION /07Z-06Z/... CIGS/VSBYS AT ALL SITES SHOULD DROP TO MVFR OVER THE NEXT FEW HOURS AS LOWER CLOUDS/FOG MOVE IN FROM THE WEST. MOST SNOW SHOWERS /WHICH WILL PRIMARILY FALL NEAR 12Z/ WILL BE OF LITTLE SIGNIFICANCE WITH VSBYS DROPPING MOSTLY DUE TO FOG. UPSTREAM OBS SHOW EMBEDDED IFR CONDITIONS...WHICH ARE POSSIBLE OVER OUR AREA AS THE SURFACE LOW MOVES BY THIS MORNING. HAVE ONLY INDICATED THIS AS TEMPO GROUPS AT THE MOST LIKELY SITES OF BGM/ITH. AT THIS POINT...CONFIDENCE IS NOT HIGH ENOUGH TO WARRANT INCLUSION AT THE OTHER LOCATIONS BUT HAVE INCLUDED A FEW CLOUDS AT IFR LEVELS FOR A HEADS UP. OTHER POSSIBLE CONCERN IS FZDZ...WHICH REALLY ONLY LOOKS TO BE POSSIBLE AT KAVP. UPSTREAM OBS SHOW MOST OF THE FZDZ SOUTH OF THE LATITUDE OF KAVP WITH FLURRIES TO THE NORTH. THUS...CONFIDENCE NOT HIGH ENOUGH TO INCLUDE IN THIS TAF PACKAGE...BUT WILL WATCH CLOSELY. WINDS WILL BE LIGHT SOUTHEASTERLY THROUGH THE MORNING...BECOMING LGT/VAR AROUND NOON...AND THEN SLOWLY BECOMING NORTHWESTERLY UP TO 10KTS THROUGH THE AFTERNOON AND EVENING. && .BGM WATCHES/WARNINGS/ADVISORIES... NY...NONE. PA...NONE. && $$ SHORT TERM...JAB AVIATION...JAB ny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ny AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE NEWPORT/MOREHEAD CITY NC 754 PM EST SUN JAN 21 2007 .SHORT TERM /REST OF TONIGHT/...RAIN HAS SPREAD OVER THE ENTIRE CWA WITH TENMPS HOVERING JUST ABOVE FREEZING DEEP INLAND. DEW POINTS AND SFC WET BULB TEMPS ARE ALSO ABOVE FREEZING INLAND. ALONG THE COAST TEMPS REMAIN IN THE LOWER 40S WHILE TEMPS OVER THE SRN AND CENTRAL WATERS HAVE RISEN INTO THE 50S IN THE PAST FEW HOURS AS A COASTAL BEGINS TO BACK UP TOWARD THE SHORE. WINDS OVER THE SRN AND CENTRAL COASTAL WATERS HAVE BECOME SE AND SRLY WHILE NEAR COASTAL LAND SITES ARE NOW REPORTING ERLY WINDS. INLAND WINDS REMAIN OUT OF THE NE. LATEST RUC STILL TRIES TO PUSH COASTAL TROF INLAND TONIGHT AND WHILE IT DOES SEEM LIKELY THAT TROF WILL PUSH INTO SOME OF THE CWA IT IS DOUBTFUL IT WILL MAKE THROUGH THE BULK OF THE CWA. STILL WITH WET BULB AND DEW POINT TEMPS AT OR ABOVE FREEZING THROUGH MUCH OF THE NIGHT DO NOT EXPECT ANYTHING MORE THAN BRIEF PERIODS OF SLEET TO MIX WITH RAIN AND NO ACCUMULATION. WILL UPDATE ZONES TO INDICATE CATEGORICAL ALL NIGHT ALL LOCATIONS. WILL ALSO TRY TO ADJUST WORDING FOR NEAR STEADY TEMPS DEEP INLAND WITH RISING TEMPS NEAR THE COAST. && .AVIATION /01Z-24Z/...STILL VFR AT THE 4 AREA TERMINALS. HOWEVER AS RAIN CONTINUES TO MOVE EAST ACROSS THE AREA CLOUD HEIGHTS WILL LOWER TO MVFR LATER THIS EVENING...EVENTUALLY BECOMING IFR AFTER MIDNIGHT. SURFACE WINDS WILL VEER THROUGHOUT THE EVENING AND OVERNIGHT...FROM EAST THIS EVENING TO SOUTH LATE TONIGHT THEN SOUTHWEST BY EARLY MONDAY MORNING. VISIBILITIES WILL COME DOWN AS WELL IN LIGHT RAIN THOUGH FOR NOW NOT EXPECTING ANYTHING LOWER THAN AROUND 3 MILES. && .MARINE...WINDS CONTINUE TO VEER THIS EVENING. GENERALLY EAST WINDS PRESENTLY WILL VEER TO SOUTHEAST LATE THIS EVENING AND INCREASE AS LOW PRESSURE MOVES ALONG THE COAST AND DEEPENS AFTER MIDNIGHT. STILL EXPECTING SMALL CRAFT CONDITIONS TO DEVELOP OVER THE SOUTHERN MARINE AREA THIS EVENING AND THE NORTHERN WATERS LATE THIS EVENING...SO NO CHANGE IN HEADLINES. MARINE ZONES LOOK GOOD SO NO CHANGES NEEDED. && .EQUIPMENT...KMHX (72305) RAOB SYSTEM WILL BE OTS FROM 00Z 1/22/07 TO 00Z 1/29/07 FOR INSTALLATION OF NEW RRS SYSTEM. FIRST FLIGHT WITH NEW SYSTEM IS SCHEDULED FOR 12Z MONDAY 1/29/07. && .MHX WATCHES/WARNINGS/ADVISORIES... NC...NONE. MARINE...SMALL CRAFT ADVISORY FROM 11 PM THIS EVENING TO 7 AM EST MONDAY FOR AMZ130-135. SMALL CRAFT ADVISORY FROM 11 PM THIS EVENING TO 4 PM EST MONDAY FOR AMZ150-152-154. SMALL CRAFT ADVISORY UNTIL 4 PM EST MONDAY FOR AMZ156. SMALL CRAFT ADVISORY UNTIL 1 PM EST MONDAY FOR AMZ158. && $$ MLF/HSA nc AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WILMINGTON NC 640 PM EST SUN JAN 21 2007 .SHORT TERM /TONIGHT/...UPDATED MADE A QUICK UPDATE TO THE GRIDS AND ZFP WITH LARGE AREA OF RAINFALL MOVING INTO THE WESTERN FORECAST AREA. EVAPORATIVE COOLING WILL ALLOW TEMPERATURES TO DROP FASTER THAN PREVIOUSLY ANTICIPATED ACROSS THE WESTERN ZONES...BUT SHOULD BOTTOM OUT IN THE UPPER 30S (EXTREME NW ZONES) TO AROUND 40 FROM NEAR FLORENCE TO ELIZABETHTOWN. MEANWHILE ALONG THE COAST AFTER INITIALLY DROPPING WITH THE ONSET OF RAIN TEMPERATURES ARE EXPECTED TO WARM AS THE COASTAL FRONT NUDGES A LITTLE FARTHER INLAND. MID TERM/MONDAY THROUGH TUESDAY NIGHT/... MAX VERTICAL MOTION WILL BE TRAVERSING THE AREA FROM N TO S EARLY IN THE PD AS FLAT WAVE MOVES OFF TOWARDS HSE AND THE UPGLIDE SHUTS DOWN. MONDAY WILL THUS START WITH CAT POPS S TO LIKELY N AND GRADUALLY TRAIL OFF TO CHANCE...BUT STILL GRADED N/S AS SOME UNDERCUTTING COLD AIR MAY STILL SQUEEZE OUT A LITTLE RAIN UNTIL AROUND 00Z AT WHICH TIME FCST SOUNDINGS BEGIN TO SHOW DEEP DRYING. MONDAY NIGHT THROUGH TUESDAY THE SFC FRONT WILL BE MOVING FARTHER AND FARTHER SOUTH BUT OVERALL BL CAA IS VERY WEAK. TEMPS WITHIN A CATEGORY OF CLIMO SAVE FOR MONDAY NIGHT WHERE CLOUDS WILL ADD A FEW DEGREES. A VEER TO MORE NWRLY IN THE 925-850 LAYER WILL BRING IN THE COOLER AIR TUESDAY NIGHT...PROBABLY ABOUT A CATEGORY BELOW CLIMO AT WORST UNLESS STRONGER DECOUPLING IS REALIZED. && .LONG TERM /WEDNESDAY THROUGH SUNDAY/... THE STORY FOR THE LONG TERM WILL BE THE CONTINUED PROGRESSIVE FLOW AND THE TRANSITION IN THE LONG WAVE UPPER FLOW PATTERN. THIS WILL RESULT IN THE EASTERN 1/2 OF THE U.S BECOMING UNDER THE INFLUENCE OF AN UPPER TROF AS THE HUDSON BAY VORTEX FLEXES ITS MUSCLES...AND THE WESTERN U.S. UNDER THE UPPER RIDGE. THIS WILL RESULT DAILY MAX/MIN TEMPS ACROSS THE ILM CWA TO LIKELY RUN BELOW THE CLIMO NORMS THRU THIS PERIOD. THE MAIN PROBLEM WITHIN THE LONG TERM WILL BE WEDNESDAY INTO THURSDAY. MODELS HAD PREVIOUSLY BEEN TRYING TO PHASE IN THE SOUTHERN S/W WITH THE NORTHERN STREAM S/W...CAUSING THE SFC BAROCLINIC ZONE OFFSHORE TO BACK AS SFC LOW DEVELOPS ACROSS THIS BOUNDARY AND INTENSIFIES AS IT MOVES UP THE EAST COAST. MODELS HAVE NOW BACKED OFF WITH THE SOUTHERN STREAM S/W TROF PHASING IN. HOWEVER MODELS STILL WANT TO AMPLIFY THE UPPER TROF WHEREBY THE SFC LOW TRACKS FARTHER OFFSHORE FROM THE ILM CWA...RESULTING IN A LOWERED CHANCE FOR PCPN LATE WED AND WED NITE. THE LOW IS STILL FCST TO PROGGED TO BOMB BUT FARTHER OFF THE NE U.S. COAST AS THE UPPER TROF BECOMES NEG TILT. THE CYCLONIC FLOW AROUND THIS MONSTER LOW WILL AFFECT THE AREA LATE WED NITE INTO FRI WITH EXCELLENT CAA UNDER GUSTY NW FLOW UNDER MOSTLY CLEAR SKIES. FOR SAT INTO SUN...GFS WANTS TO FINALLY EJECT THE SOUTHWEST U.S. UPPER LOW TO THE NORTHEAST. HOWEVER HAVE HELD BACK IN BUYING THIS SOLUTION DUE TO MODELS OVERALL PERFORMANCE WITH THIS FEATURE AS OF LATE. && .AVIATION /20Z-18Z/... FRONT AND ASSOCIATED RAINFALL SEEM TO BE AN HOUR OR TWO SLOWER THAN MODEL RUNS. WILL DELAY WIND SHIFT TO THE SOUTH TILL AFTER 06Z. CEILINGS WILL QUICKLY LOWER TO MVFR SHORTLY AFTER 01Z...BECOMING IFR A FEW HOURS LATER AS MODERATE RAINFALL BEGINS. THINK WINDS OVER 10 KTS WILL KEEP VISIBILITIES JUST ABOVE IFR AT AROUND 3SM. STRONGEST OMEGA WILL BE FROM 04Z-13Z AS FRONT DRAPES ACROSS THE MIDDLE...THEN SOUTHERN PORTION OF THE CWA. MODELS IN DECENT AGREEMENT IN SHIFTING WINDS TO THE SOUTHWEST...THEN WEST AS FRONT CONTINUES TO SAG SOUTH AFTER 13Z. PRECIP WILL SHUT OFF FROM NORTH TO SOUTH AFTER 14Z...HOWEVER CEILINGS WILL LIKELY LIFT TO ONLY MVFR THROUGH THE END OF THE FORECAST PERIOD. && .MARINE... .SHORT TERM/TONIGHT/...UPDATED AFTER COORDINATION WITH CHS DECIDED TO EXPAND THE SMALL CRAFT ADVISORY SOUTHWARD TO THE SOUTH SANTEE RIVER. LOCAL WRF...RUC AND OTHER MODELS INDICATE THAT THERE COULD BE A PERIOD OF MARGINAL SMALL CRAFT CONDITIONS OFF PORTIONS OF THE SC COAST. BUOY 41004 ALREADY HAS GUSTS TO 25 KTS AND THERE ARE ALSO GUSTS TO AROUND 21 KTS AT BUOY 41036 AND INSHORE AT BUOY 41035. IN ADDITION...SPRING MAID PIER IS MEASURING SPEEDS IN THE 15-20 KT RANGE. MID TERM/MONDAY THROUGH TUESDAY NIGHT/... SCA TO BEGIN THE PD FOR NRN ZONES AS WIND AND SEAS EXPECTED TO BE BORDERLINE OUT ALONG FRYING PAN SHOALS. FCST IS STILL A COMPROMISE BETWEEN THE MORE AGGRESSIVE GFS/WNA AND THE WRF/REEFCAST. BY MIDDAY A VEER TO OFFSHORE AND A TROUGH INDUCED DEC IN SPEEDS WILL ALLOW CONDITIONS TO SETTLE BUT SCA MAY HAVE TO BE LOWERED TO SCEC FOR MONDAY PM FOR SOME OR ALL ZONES. FLOW REMAINS OFFSHORE FOR THE REMAINDER OF THE PD WITH A GRADIENT THAT WILL PRECLUDE ANY ADVISORIES BUT PROBABLY ALSO PRECLUDE THE DESCRIPTOR `TRANQUIL`...AVERAGING IN THE 10 TO 15 KT RANGE. LONG TERM /WEDNESDAY THROUGH FRIDAY/... FOR THIS PERIOD...AMPLIFIED UPPER TROF WILL BECOME THE DOMINATE FEATURE ACROSS THE AREA. THE EVOLUTION TO THIS FINAL FEATURE WILL OCCUR WED INTO THU AT WHICH TIME A NORTHERN STREAM S/W TROF WILL DIVE SOUTHEAST FROM SOUTH CENTRAL CANADA TO THE NE STATES...CARVING OUT THE WELL AMPLIFIED UPPER TROF. EXCELLENT AIR-SEA DYNAMICS WILL CAUSE A SFC BOMB OFF THE NE STATES. AT WHAT POSITION NEAR THE U.S. EAST COAST THIS OCCURS REMAINS A MYSTERY AND IS SUBJECT TO ANY POSSIBLE SOUTHERN STREAM S/W ENERGY INFLUENCES. FOR NOW HAVE INDICATED THE CYCLONIC FLOW FROM THE BOMBING LOW TO AFFECT THE AREA WITH EXCELLENT CAA LATE WED NITE INTO FRI ALONG WITH A WELL TIGHTENED SFC PG. THIS WILL CULMINATE TO ATLEAST A STRONG SCA EVENT ACROSS THE ILM WATERS WITH GUSTS TO GALE FORCE. AT THIS TIME...SUSTAINED GALES HAVE NOT BEEN RULED OUT. MUCH WILL DEPEND ON ANY INFLUENCES FROM THE SOUTHERN WESTERLIES. WW3 NUMBERS SEEM A BIT LOW NEAR THE COAST DURING THIS STRONG SCA EVENT AND HAVE BOOSTED THEM UPWARDS BY 1-2 FEET. DUE TO FETCH LIMITATIONS...A RANGE OF SEAS WILL BE NEEDED. && .ILM WATCHES/WARNINGS/ADVISORIES... NC...NONE. SC...NONE. MARINE...SMALL CRAFT ADVISORY THROUGH 2 PM EST MONDAY FOR AMZ250- 252-254-256. && $$ SHORT TERM...PFAFF AVIATION...DL nc AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GRAND FORKS ND 715 PM CST MON JAN 22 2007 .CURRENT OBSERVATIONAL OVERVIEW... 01Z SURFACE ANALYSIS DEPICTED LOW PRESSURE OVER ONTARIO PROVINCE WITH ASSOCIATED TROUGH BACK INTO CENTRAL SOUTH DAKOTA. STRONG PRESSURE FALLS WERE NOTED AHEAD OF FEATURE ACROSS MINNESOTA. LATEST WATER VAPOR IMAGERY SHOWED POSITIVE PHASE OF PNA WITH AIRMASS TRAJECTORY FOR CWFA COMING OFF PACIFIC/WESTERN CANADA. .FORECAST DETAILS... MAIN FORECAST CHALLENGE CONCERNS DEGREE OF MERCURY DESCENT OVERNIGHT AS UPSTREAM CLOUDINESS ADVANCES SOUTHEAST INTO CWFA AHEAD OF CLIPPER TYPE FEATURE FOR TUESDAY. GOOD TEMP/DP SPREAD CURRENTLY OVER CWFA SHOULD ALLOW BEST COOLING ACROSS NORTHWEST MINNESOTA ESPECIALLY BEFORE 06Z. WITH LATEST GUIDANCE PRETTY MUCH HOLDING ITS OWN WITH CURRENT CONDITIONS APPEARS ONLY MINOR TWEAKS OF TEMPS NEEDED. WILL LEAVE SLIGHT POP CHANCES ACROSS THE WEST FOR AFTER MIDNIGHT HOWEVER HIGH LOW LEVEL CONDENSATION PRESSURE DEFICITS WILL WASTE MUCH OF INITIAL LIFT TO FURTHER SATURATE COLUMN. && .AVIATION... LATEST RUC SUGGESTS INCREASE IN MOISTURE OVERNIGHT IN 925MB LAYER WITH BEST CHANCES FOR DEVELOPING MVFR CONDITIONS ALONG AND NORTH OF HIGHWAY 2. ELSEWHERE EXPECT VFR CONDITIONS TO PERSIST. GFK/BJI TAF SITES WILL BE UPDATED FOR LATER ARRIVAL TIME OF LOWER CIGS TO AFTER MIDNIGHT. && .FGF WATCHES/WARNINGS/ADVISORIES... ND...NONE. MN...NONE. && $$ BERG nd AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE GRAND FORKS ND 1028 AM CST MON JAN 22 2007 .UPDATE... MAIN CHALLENGE FOR THE MORNING UPDATE IS CLOUD TRENDS AND TEMPERATURES. BAND OF LOWER CLOUDS LINGERS IN THE EAST WITH LOWER CLOUD AMOUNTS TO THE WEST. LOWER CLOUDS IN THE EAST TO PUSH OFF TO THE EAST TODAY LEAVING MOST AREAS PARTLY CLOUDY. COLD POCKET THIS MORNING IN SOUTH EAST ND DUE TO MINIMAL CLOUDS OVERNIGHT. CHALLENGE WILL BE HOW MUCH TEMPERATURE RECOVERY WILL OCCUR IN THIS AREA. WARMER SOUTH WEST WINDS WILL HELP TEMPERATURE RECOVERY IN THAT AREA. DID LOWER TEMPERATURES A DEGREE OR TWO ACROSS THE SOUTH...BUT EXPECT GOOD REBOUND IN TEMPERATURES TODAY. NAM12 AND RUC GUIDANCE IN LINE WITH THIS THINKING. && .FGF WATCHES/WARNINGS/ADVISORIES... ND...NONE. MN...NONE. && $$ GODON/TORBORG nd AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WILMINGTON OH 520 AM EST MON JAN 22 2007 .SHORT TERM /THIS MORNING/... SRN FCST AREA WILL NOT DROP BELOW FREEZING THIS MORNING. HAVE REMOVED ANY MENTION OF FREEZING PRECIP BUT KEPT FOG AND PATCHY DZ IN FOR EARLY PART OF THE MORNING OVER SRN 1/2 OF FCST AREA. FRANKS && .PREVIOUS DISCUSSIONS... ISSUED 335 AM EST MON JAN 22 2007 SHORT TERM /TODAY THROUGH WEDNESDAY NIGHT/ CURRENT ADVY OVER THE S WILL BE DROPPED WITH THE 4 AM PACKAGE AS TEMPS REMAIN ABOVE FREEZING FOR MUCH OF THE AREA ALONG AND S OF OHRIVER EARLY THIS MORNING. COOLER READINGS OVER THE N WITH EVEN COOLER AIR WORKING IN MAY HELP CONTINUE SOME VERY PATCHY -FZDZ THROUGH THE EARLY MORNING TODAY...BUT RETURNS FROM RADAR AND SFC OBS ARE SEVERELY LACKING AND RETHINKING IT HAS ME DROP THE ADVY FOR ENTIRE CWA. BELIEVE THAT ANY PRECIP WILL BE SPOTTY AT BEST TODAY. MAIN PROBLEMS THIS MORNING WILL BE DUE TO REDUCED VSBYS IN THE LOW CLOUDS AND PATCHY FOG. SURFACE LOW TO MOVE E AND EXIT THE OHIO VALLEY THIS MORNING. COLD AIR WILL BE PULLED INTO THE REGION AS A WEAK RIDGE OF HIGH PRESSURE BUILDS OVER ERN OHIO VALLEY TONIGHT AND TUESDAY. THIS RIDGE WILL BE SITUATED OVER A SIGNIFICANT AMOUNT OF LOW LEVEL MOISTURE AND HELP ADD SOME FORCING WHEN A MID LEVEL S/W PASSES OVER TUES NIGHT. THE SFC RIDGE BREAKS DOWN AS ANOTHER REINFORCING SHOT OF COLD AIR BRINGS SCT AFTERNOON SNOW SHOWERS ON WED. TUES NIGHT WILL SEE SOME MID LEVEL FORCING WITH AN APPROACHING H5 VORT BEHIND A WEAK H5 TROF THAT IS WORKING THROUGH OHVLY. A STRETCHED OUT VORT WILL SET UP OVER CWA...RUNNING FROM THE UPPER MIDWEST TO THE MID-ATLANTIC. GFS IS STRONGER WITH H5 S/W BUT MUCH FURTHER S WITH AFFOREMENTIONED VORT. THE TROF WILL BRING A REINFORCING SHOT OF COLD AIR TO THE REGION AND POSSIBLY SPARK SOME INSTABILITY SNOW SHOWERS. TRIED TO LOWER THE CHANCE OF SNOW BOTH TUES NIGHT AND EARLY WED...BELIEVE THAT ANY ACTIVITY DURING THIS TIME WOULD BE VERY LIGHT AND/OR WIDELY SCATTERED. FRANKS LONG TERM /THURSDAY THROUGH SUNDAY/... HAVE NOT CHANGED FCST STARTING WITH THURS MORN...PREV DISC FOLLOWS. MID LEVEL TROUGH IN PLACE ACROSS THE GREAT LAKES AT THE START OF THE LONG TERM PERIOD. SHORT WAVE ENERGY IS FORECAST TO DROP DOWN ACROSS OUR AREA WEDNESDAY INTO THURSDAY. THIS SHOULD LEAD TO AT LEAST SOME SCATTERED SNOW SHOWER ACTIVITY. HAVE KEPT POPS RELATIVELY LOW THOUGH AS AMOUNTS LOOK TO BE LIGHT AND THERE ARE STILL SOME TIMING ISSUES. REINFORCING SHOT OF ARCTIC AIR WILL ALSO PUSH DOWN ACROSS THE REGION THROUGH MID TO LATE WEEK AND THIS SHOULD HELP KEEP TEMPS BELOW NORMAL EARLY IN THE LONG TERM PERIOD. MID LEVEL RIDGING WILL DEVELOP ACROSS THE AREA FRIDAY INTO EARLY SATURDAY. AS IT DOES...WE SHOULD SEE SOME IMPROVEMENT IN SKY CONDITIONS AND A LITTLE BIT OF A WARM UP. HOWEVER...THE 12Z GFS IS TRYING TO REESTABLISH THE TROUGH OVER THE GREAT LAKES LATE IN THE PERIOD. WILL THEREFORE BRING IN SOME COLDER TEMPS AND A CHANCE OF PRECIPITATION FOR SUNDAY. && .AVIATION /06Z-06Z/... BROAD AREA OF LO PRES AT SFC ACRS NRN INDIANA ATTM. WIDESPREAD LIFR/VLIFR CONDITIONS PERSIST ACRS OH VLY WITH POCKETS OF -DZ AND FLURRIES. MODEL SOUNDINGS INDCG COMPLETELY SATURATED ATMOSPHERE BLO 5KFT. SOUNDINGS CONTINUE TO SUPPORT -DZ/FZDZ POTENTIAL FOR THE REMAINDER OF THE NIGHT AND THRU MIDDAY TODAY AS INVERSION WILL KEEP LO LVL MOISTURE TRAPPED WITH MUCH DRIER AIRMASS ABV 850MB AND NO APPRECIABLE LIFT FOR MOISTURE TO WORK WITH. QUESTION THEN COMES DOWN TO WHAT THE TEMPS ARE AT THE SFC...AND WHETHER PCPN FALLS AS -DZ OR -FZDZ. WITH SFC LO PASSING TO NORTH OF TAFS OVER NEXT SVRL HOURS...LO LVL CAA WILL DVLP ON BACK SIDE OF SFC LO. 32F ISOTHERM SITTING NEAR I-70 ATTM...AND EXPECT TEMPS TO BEGIN FALLING AT KDAY/ KCMH/KLCK MOMENTARILY. FURTHER SOUTH...00Z RUC/NAM BOTH INDICATE TEMPS WILL DROP BELOW FREEZING BTWN 09-12Z AT KILN...AND AROUND 12Z AT KCVG/KLUK. NOW APPEARS THAT MAY ONLY SEE A BRIEF PERIOD OF -FZDZ FOR KCVG/KLUK IN THE MORNING...AS TEMPS SHOULD RISE BACK ABV 32F BY MID MRNG. FURTHER NORTH...-FZDZ WILL PERSIST THRU MRNG HOURS. AS MID LVLS COOL ON MON...EXPECT -DZ/FZDZ TO END BY ERLY AFTN. CIGS/VSBYS WILL SLOWLY IMPROVE THRU MRNG HOURS... WITH VFR VSBYS EXPECTED BY LATE AFTN. SC DECK WILL REMAIN SOLIDLY ENTRENCHED ACRS REGION THRU FCST PERIOD...BUT SHOULD SEE GRADUAL LIFTING INTO MVFR CAT BY LATE AFTN/EVNG. RYAN && .ILN WATCHES/WARNINGS/ADVISORIES... OH...NONE. KY...NONE. IN...NONE. && $$ oh AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WILMINGTON OH 335 AM EST MON JAN 22 2007 .SHORT TERM /TODAY THROUGH WEDNESDAY NIGHT/... CURRENT ADVY OVER THE S WILL BE DROPPED WITH THE 4 AM PACKAGE AS TEMPS REMAIN ABOVE FREEZING FOR MUCH OF THE AREA ALONG AND S OF OHRIVER EARLY THIS MORNING. COOLER READINGS OVER THE N WITH EVEN COOLER AIR WORKING IN MAY HELP CONTINUE SOME VERY PATCHY -FZDZ THROUGH THE EARLY MORNING TODAY...BUT RETURNS FROM RADAR AND SFC OBS ARE SEVERELY LACKING AND RETHINKING IT HAS ME DROP THE ADVY FOR ENTIRE CWA. BELIEVE THAT ANY PRECIP WILL BE SPOTTY AT BEST TODAY. MAIN PROBLEMS THIS MORNING WILL BE DUE TO REDUCED VSBYS IN THE LOW CLOUDS AND PATCHY FOG. SURFACE LOW TO MOVE E AND EXIT THE OHIO VALLEY THIS MORNING. COLD AIR WILL BE PULLED INTO THE REGION AS A WEAK RIDGE OF HIGH PRESSURE BUILDS OVER ERN OHIO VALLEY TONIGHT AND TUESDAY. THIS RIDGE WILL BE SITUATED OVER A SIGNIFICANT AMOUNT OF LOW LEVEL MOISTURE AND HELP ADD SOME FORCING WHEN A MID LEVEL S/W PASSES OVER TUES NIGHT. THE SFC RIDGE BREAKS DOWN AS ANOTHER REINFORCING SHOT OF COLD AIR BRINGS SCT AFTERNOON SNOW SHOWERS ON WED. TUES NIGHT WILL SEE SOME MID LEVEL FORCING WITH AN APPROACHING H5 VORT BEHIND A WEAK H5 TROF THAT IS WORKING THROUGH OHVLY. A STRETCHED OUT VORT WILL SET UP OVER CWA...RUNNING FROM THE UPPER MIDWEST TO THE MID-ATLANTIC. GFS IS STRONGER WITH H5 S/W BUT MUCH FURTHER S WITH AFFOREMENTIONED VORT. THE TROF WILL BRING A REINFORCING SHOT OF COLD AIR TO THE REGION AND POSSIBLY SPARK SOME INSTABILITY SNOW SHOWERS. TRIED TO LOWER THE CHANCE OF SNOW BOTH TUES NIGHT AND EARLY WED...BELIEVE THAT ANY ACTIVITY DURING THIS TIME WOULD BE VERY LIGHT AND/OR WIDELY SCATTERED. FRANKS && .LONG TERM /THURSDAY THROUGH SUNDAY/... HAVE NOT CHANGED FCST STARTING WITH THURS MORN...PREV DISC FOLLOWS. MID LEVEL TROUGH IN PLACE ACROSS THE GREAT LAKES AT THE START OF THE LONG TERM PERIOD. SHORT WAVE ENERGY IS FORECAST TO DROP DOWN ACROSS OUR AREA WEDNESDAY INTO THURSDAY. THIS SHOULD LEAD TO AT LEAST SOME SCATTERED SNOW SHOWER ACTIVITY. HAVE KEPT POPS RELATIVELY LOW THOUGH AS AMOUNTS LOOK TO BE LIGHT AND THERE ARE STILL SOME TIMING ISSUES. REINFORCING SHOT OF ARCTIC AIR WILL ALSO PUSH DOWN ACROSS THE REGION THROUGH MID TO LATE WEEK AND THIS SHOULD HELP KEEP TEMPS BELOW NORMAL EARLY IN THE LONG TERM PERIOD. MID LEVEL RIDGING WILL DEVELOP ACROSS THE AREA FRIDAY INTO EARLY SATURDAY. AS IT DOES...WE SHOULD SEE SOME IMPROVEMENT IN SKY CONDITIONS AND A LITTLE BIT OF A WARM UP. HOWEVER...THE 12Z GFS IS TRYING TO REESTABLISH THE TROUGH OVER THE GREAT LAKES LATE IN THE PERIOD. WILL THEREFORE BRING IN SOME COLDER TEMPS AND A CHANCE OF PRECIPITATION FOR SUNDAY. && .AVIATION /06Z-06Z/... BROAD AREA OF LO PRES AT SFC ACRS NRN INDIANA ATTM. WIDESPREAD LIFR/VLIFR CONDITIONS PERSIST ACRS OH VLY WITH POCKETS OF -DZ AND FLURRIES. MODEL SOUNDINGS INDCG COMPLETELY SATURATED ATMOSPHERE BLO 5KFT. SOUNDINGS CONTINUE TO SUPPORT -DZ/FZDZ POTENTIAL FOR THE REMAINDER OF THE NIGHT AND THRU MIDDAY TODAY AS INVERSION WILL KEEP LO LVL MOISTURE TRAPPED WITH MUCH DRIER AIRMASS ABV 850MB AND NO APPRECIABLE LIFT FOR MOISTURE TO WORK WITH. QUESTION THEN COMES DOWN TO WHAT THE TEMPS ARE AT THE SFC...AND WHETHER PCPN FALLS AS -DZ OR -FZDZ. WITH SFC LO PASSING TO NORTH OF TAFS OVER NEXT SVRL HOURS...LO LVL CAA WILL DVLP ON BACK SIDE OF SFC LO. 32F ISOTHERM SITTING NEAR I-70 ATTM...AND EXPECT TEMPS TO BEGIN FALLING AT KDAY/ KCMH/KLCK MOMENTARILY. FURTHER SOUTH...00Z RUC/NAM BOTH INDICATE TEMPS WILL DROP BELOW FREEZING BTWN 09-12Z AT KILN...AND AROUND 12Z AT KCVG/KLUK. NOW APPEARS THAT MAY ONLY SEE A BRIEF PERIOD OF -FZDZ FOR KCVG/KLUK IN THE MORNING...AS TEMPS SHOULD RISE BACK ABV 32F BY MID MRNG. FURTHER NORTH...-FZDZ WILL PERSIST THRU MRNG HOURS. AS MID LVLS COOL ON MON...EXPECT -DZ/FZDZ TO END BY ERLY AFTN. CIGS/VSBYS WILL SLOWLY IMPROVE THRU MRNG HOURS... WITH VFR VSBYS EXPECTED BY LATE AFTN. SC DECK WILL REMAIN SOLIDLY ENTRENCHED ACRS REGION THRU FCST PERIOD...BUT SHOULD SEE GRADUAL LIFTING INTO MVFR CAT BY LATE AFTN/EVNG. RYAN && .ILN WATCHES/WARNINGS/ADVISORIES... OH...NONE. KY...NONE. IN...NONE. && $$ oh AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE WILMINGTON OH 1244 AM EST MON JAN 22 2007 .AVIATION /06Z-06Z/... BROAD AREA OF LO PRES AT SFC ACRS NRN INDIANA ATTM. WIDESPREAD LIFR/VLIFR CONDITIONS PERSIST ACRS OH VLY WITH POCKETS OF -DZ AND FLURRIES. MODEL SOUNDINGS INDCG COMPLETELY SATURATED ATMOSPHERE BLO 5KFT. SOUNDINGS CONTINUE TO SUPPORT -DZ/FZDZ POTENTIAL FOR THE REMAINDER OF THE NIGHT AND THRU MIDDAY TODAY AS INVERSION WILL KEEP LO LVL MOISTURE TRAPPED WITH MUCH DRIER AIRMASS ABV 850MB AND NO APPRECIABLE LIFT FOR MOISTURE TO WORK WITH. QUESTION THEN COMES DOWN TO WHAT THE TEMPS ARE AT THE SFC...AND WHETHER PCPN FALLS AS -DZ OR -FZDZ. WITH SFC LO PASSING TO NORTH OF TAFS OVER NEXT SVRL HOURS...LO LVL CAA WILL DVLP ON BACK SIDE OF SFC LO. 32F ISOTHERM SITTING NEAR I-70 ATTM...AND EXPECT TEMPS TO BEGIN FALLING AT KDAY/ KCMH/KLCK MOMENTARILY. FURTHER SOUTH...00Z RUC/NAM BOTH INDICATE TEMPS WILL DROP BELOW FREEZING BTWN 09-12Z AT KILN...AND AROUND 12Z AT KCVG/KLUK. NOW APPEARS THAT MAY ONLY SEE A BRIEF PERIOD OF -FZDZ FOR KCVG/KLUK IN THE MORNING...AS TEMPS SHOULD RISE BACK ABV 32F BY MID MRNG. FURTHER NORTH...-FZDZ WILL PERSIST THRU MRNG HOURS. AS MID LVLS COOL ON MON...EXPECT -DZ/FZDZ TO END BY ERLY AFTN. CIGS/VSBYS WILL SLOWLY IMPROVE THRU MRNG HOURS... WITH VFR VSBYS EXPECTED BY LATE AFTN. SC DECK WILL REMAIN SOLIDLY ENTRENCHED ACRS REGION THRU FCST PERIOD...BUT SHOULD SEE GRADUAL LIFTING INTO MVFR CAT BY LATE AFTN/EVNG. RYAN && .PREV DISCUSSION... /ISSUED 1021 PM EST SUN JAN 21 2007/ SHORT TERM /REST OF TONIGHT/... UPPER LEVEL S/W TROUGH TO TRACK EAST THRU THE GREAT LAKES TONIGHT. ASSOCIATED WEAK SURFACE WAVE MOVING INTO WRN INDIANA TO TRACK E ACRS NRN OH LATE TNGT. LATEST IR SATL IMGRY SHOWS COLDER CLOUD TOPS MOVG INTO NW OH AHD OF THE UPPER TROF. THEREFORE ICE CRYSTAL CONTENT IN THESE CLDS SHUD LEAD TO SCTD SNOW SHOWERS. AS THESE ENHANCED CLDS MOVE OUT LATE TNGT AND WITH SFC TEMPS DROPPING BEHIND WEAK FRONT SOME FREEZING DRIZZLE WL REMAIN PSBL. HAVE ADJUSTED TEMPS A LTL WARMER IN THE SOUTH AND THEN DROP AT OR JUST BLO FREEZING LATE TNGT. HAVE ALSO ADDED MENT OF SNOW SHOWERS ACRS THE CNTRL AND THE N LATE TNGT/ERLY MON. WL CONT CURRENT HEADLINES. PREV DISCUSSION... /ISSUED 410 PM EST SUN JAN 21 2007/ SHORT TERM /TONIGHT THROUGH TUESDAY NIGHT/... THE PRIMARY EMPHASIS HAS BEEN PLACED ON THE WEATHER SYSTEM CURRENTLY EFFECTING THE OHIO VALLEY. THE LOW PRESSURE SYSTEM WAS LOCATED OVER MO SUN AFTERNOON. THE LOW PRESSURE AREA WILL MOVE EAST NORTHEAST ACROSS INDIANA AND OH THROUGH 06Z MON AND INTO WESTERN PA BY 12Z MON. THE ACCUMULATING SNOWS WITH THE SYSTEM HAVE ENDED FOR THE MOST PART. SOME WARMING IS OCCURRING IN THE SOUTH WHERE AREAS OF DRIZZLE WAS OCCURRING THIS AFTERNOON. AREAS IN THE NORTH HAVE CONTINUED TO SEE FREEZING DRIZZLE AND SOME A MIX WITH LIGHT SNOW. PLENTY OF MOISTURE IN THE LOW LEVELS OF THE ATMOSPHERE WILL CONTINUE TO PRODUCE AREAS OF DRIZZLE/FREEZING DRIZZLE...EVEN AS THE MID LEVELS DRY OUT. THE POTENTIAL FOR FREEZING DRIZZLE WILL CONTINUE INTO MONDAY MORNING IN THE NORTH AND IN SOUTH AS TEMPERATURES DROP BELOW FREEZING AGAIN. FOR THIS REASON...A WINTER WEATHER ADVISORY HAS BEEN EXTENDED IN THE NORTH AND ISSUED FOR THE SOUTH PART OF THE FORECAST AREA. AN UPPER LEVEL SYSTEM WILL BRING A CHANCE OF SNOW SHOWERS TO THE NORTH PART OF THE FORECAST AREA MONDAY AFTERNOON. WILL SEE ANOTHER CHANCE FOR SNOW SHOWERS LATE TUESDAY NIGHT IN THE NORTH AS A SHORT WAVE APPROACHES. REMAINED CLOSER TO GFS MOS FOR TEMPERATURES. LONG TERM /WEDNESDAY THROUGH SUNDAY/... MID LEVEL TROUGH IN PLACE ACROSS THE GREAT LAKES AT THE START OF THE LONG TERM PERIOD. SHORT WAVE ENERGY IS FORECAST TO DROP DOWN ACROSS OUR AREA WEDNESDAY INTO THURSDAY. THIS SHOULD LEAD TO AT LEAST SOME SCATTERED SNOW SHOWER ACTIVITY. HAVE KEPT POPS RELATIVELY LOW THOUGH AS AMOUNTS LOOK TO BE LIGHT AND THERE ARE STILL SOME TIMING ISSUES. REINFORCING SHOT OF ARCTIC AIR WILL ALSO PUSH DOWN ACROSS THE REGION THROUGH MID TO LATE WEEK AND THIS SHOULD HELP KEEP TEMPS BELOW NORMAL EARLY IN THE LONG TERM PERIOD. MID LEVEL RIDGING WILL DEVELOP ACROSS THE AREA FRIDAY INTO EARLY SATURDAY. AS IT DOES...WE SHOULD SEE SOME IMPROVEMENT IN SKY CONDITIONS AND A LITTLE BIT OF A WARM UP. HOWEVER...THE 12Z GFS IS TRYING TO REESTABLISH THE TROUGH OVER THE GREAT LAKES LATE IN THE PERIOD. WILL THEREFORE BRING IN SOME COLDER TEMPS AND A CHANCE OF PRECIPITATION FOR SUNDAY. && .ILN WATCHES/WARNINGS/ADVISORIES... OH...WINTER WEATHER ADVISORY UNTIL 10 AM EST THIS MORNING FOR OHZ026-034- 035-042>046-051>056-060>065-070>074-077>082-088. KY...WINTER WEATHER ADVISORY UNTIL 10 AM EST THIS MORNING FOR KYZ089>100. IN...WINTER WEATHER ADVISORY UNTIL 10 AM EST THIS MORNING FOR INZ050-058- 059-066-073>075-080. && $$ oh AREA FORECAST DISCUSSION FOR SOUTHEAST SD/SOUTHWEST MN/NORTHWEST IA NATIONAL WEATHER SERVICE SIOUX FALLS SD 1210 PM CST TUE JAN 23 2007 .DISCUSSION STEADY LIGHT SNOW MOVING RPDLY SEWD OUT OF AREA AT NOON. UPDATED FCSTS TO KEEP SCT LIGHT SNOW SHWRS IN WITH LTL ACCUM. SHORT TERM GUIDANCE SUGGESTS CONTD CLOUDS WITH BREAKS AND SUPPORT OF A FEW LIGHT SNOW SHWRS. RUC HAS BEEN SUGGESTING A RESURGENCE LATE AFTN INTO VERY ERY EVENING...BUT EVEN IF THIS HAPPENS IT STILL WOULD PRBLY BE LESS ORGANIZED THAN THIS MORNINGS LGT SNOW BATCH SO WENT THE SCT LIGHT SNOW SHWR ROUTE FOR THIS AFTN. TEMPS WILL GO UP JUST A FEW DEGS FROM CURNT LEVELS...A LITTLE MORE IN NWRN IA WHERE SNOW IS NOW ENDING. INFLUX OF COLD AIR OVER NRN ESPLY NERN FCST AREA WILL KEEP THE RELATIVE HEAT WAVE FROM GETTING TOO VIOLENT. && && .AVIATION... ALONG WITH THE MOVING OUT OF THE STEADY SNOW AREA...CIGS AND ESPLY VSBYS WILL BE BETTER THRU 00Z THAN ERYR FCST. STILL SOME MVFR CIGS ARND AND PSBL BRIEF 3 TO 5 MI VSBYS IN LGT SNOW SHWRS...BUT GNRLY NOT TOO BAD ESPLY SINCE CIGS SHUD BE 2 TO 3 THSD FEET AT LOWEST. && .FSD WATCHES/WARNINGS/ADVISORIES... SD...NONE. MN...NONE. IA...NONE. NE...NONE. && $$ WILLIAMS sd AREA FORECAST DISCUSSION FOR SOUTHEAST SD/SOUTHWEST MN/NORTHWEST IA NATIONAL WEATHER SERVICE SIOUX FALLS SD 1003 AM CST TUE JAN 23 2007 .DISCUSSION AREA OF LGT SNOW MOVING THRU CWA THIS MRNG WELL DEPICTED IN THE SHORT TERM ON THE RUC. NAM 06Z SNDGS TOO COLD IN WRN ZONES. HEAVIEST SNOW OF 0.5 TO 1 INCH WILL BE FROM MADISON THRU KFSD TO KCKP BETWEEN 15Z AND 18Z...THEN BETTER DYNAMICS SHIFT INTO FAR ERN ZONES FOR THIS AFTN...BUT THIS AREA WL SEE LIGHTER SNOW AS SECOND SURGE WILL BE WEAKER THAN THIS MRNG. TOTAL SNOW OF 1 TO 2 INCHES LIKELY ALONG AXIS FROM KHON TO KFSD TO KSLB BY THE TIME THINGS END LATE AFTN OR EARLY EVNG. GRIDS AND ZFP ALREADY UPDATED. && .PREVIOUS DISCUSSION... TEMPS HAVE WARMED ACROSS THE WESTERN HALF OF FORECAST AREA MUCH OF THE NIGHT AS WEAK WARM AIR ADVECTION COMBINES WITH INCREASING CLOUD COVER. AM NOT EXPECTING TEMPERATURES TO RISE MUCH MORE TODAY IN SOUTHEASTERN SOUTH DAKOTA...BUT WILL CONTINUE TO RISE THROUGHOUT THE MORNING IN SOUTHWEST MINNESOTA AND NORTHWEST IOWA. WITH THAT SAID...TEMPS WERE SOMEWHAT TRICKY TRYING TO FIGURE OUT HOW WARM LOCATIONS WOULD GET PRIOR TO APPROACHING WAVE. SHORTWAVE MOVING OUT OF EASTERN MONTANA THIS MORNING WILL RESULT IN LIGHT SNOWFALL TODAY ACROSS PORTIONS OF FORECAST AREA. NOT A LOT TO HANG HAT ONTO DYNAMICALLY...WITH VERY WEAK MIDLEVEL FRONTOGENESIS AND NOT A LOT OF UPPER LEVEL SUPPORT OUTSIDE AREA BEING LOCATED IN LEFT FRONT OF JET STREAK WORKING DOWN FROM ALBERTA. NAM INITIALIZATION/ENSEMBLES ARE TOO DRY COMPARED TO UPSTREAM OBSERVATIONS...WHILE THE WRF AND GFS DEPICT SOME LIGHT PRECIP WITH THE WAVE. EXPECT A LOW QPF HIGH POP EVENT...WITH SNOW ACCUMULATIONS REMAINING AROUND AN INCH OR LESS IN A BAND EXTENDING FROM BROOKINGS SOUTH DAKOTA TO STORM LAKE IOWA. SNOW SHOULD GRADUALLY TAPER OFF THIS EVENING...AS WEAK UPPER LEVEL SUPPORT DIES AWAY AND WAVE PULLS TO THE SOUTH AND EAST. A SECOND WEAK WAVE IS EXPECTED TO MOVE ACROSS FORECAST AREA ON WEDNESDAY. DESPITE BETTER TROP UNDULATION...THE LOWER LEVEL REMAIN RELATIVELY DRY AND HAVE CONTINUED WITH DRY FORECAST. TEMPERATURES BEGINS TO REBOUND ON THURSDAY AS MILD AIR MASS MOVES BACK INTO THE REGION. HAVE BEEN SOMEWHAT CONSERVATIVE IN WARMING WITH SOUTHEASTERLY FLOW AND SNOW COVER IN EASTERN CWA. WITH GRADIENT INCREASING THURSDAY NIGHT...LOWER LEVELS WILL LIKELY REMAIN FAIRLY WELL MIXED AND HAVE RAISED FORECAST LOWS AHEAD OF APPROACHING FRONT. A STRONG COLD FRONT WILL MOVE THROUGH ON FRIDAY. FAVORED THE TIMING OF THE SLOWER GFS TO WRF. AHEAD OF THE FRONT...VERY WARM AIR IN PLACE AND WHILE THERE WILL BE A FEW CLOUDS AROUND...THE SW FLOW AT MOST LEVELS IS NOT CONDUCIVE TO WIDESPREAD STRATUS SO THERE SHOULD BE SOME SUN TO HELP OUT. AND WITH FROPA DURING THE DAY...AS WINDS SHIFT TO NORTHWEST...SHOULD BE FAIRLY EFFICIENT MIXING. THEREFORE RAISED TEMPS ACROSS THE AREA ABOVE FREEZING WITH 40S IN SOUTH CENTRAL SD. WITHOUT SNOWCOVER...MOST PLACES WOULD EASILY RISE TO 40 DEGREES BUT BELIEVE THAT SNOWCOVER MAY PREVENT TEMPS FROM WARMING TOO MUCH. AFTER FROPA...A FEW MORE CLOUDS WILL MOVE IN FRIDAY NIGHT BUT LACK OF LARGE SCALE LIFT AND MOISTURE SHOULD ALLOW SKIES TO REMAIN PARTLY CLOUDY. IT SHOULD BE FAIRLY WINDY SO TEMPS WILL REMAIN AROUND 10 DEGREES. ON SATURDAY...WHILE THE OPERATIONAL GFS HINTS MUCH COLDER TEMPS WITH 925 MB TEMPS BELOW -15C IN MOST LOCALES...THE ENSEMBLE MEAN OF THE 00Z GFS IS ABOVE 4C WARMER. WITH THE WAVE MOVING INTO THE GREAT LAKES...NOT CONDUCIVE TO A REALLY STRONG ARCTIC PUSH AND DO FAVOR CLOSER TO ENSEMBLE MEAN. ALSO SNOW WILL LIKELY BE MELTED WEST OF THE JAMES RIVER AND ALONG HWY 14 WHERE LESS THAN 2 INCHES IS CURRENTLY ON THE GROUND. SO RAISED MAX TEMPS A COUPLE OF DEGREES OVER PREVIOUS FORECAST AS CONFIDENCE IN THIS AREA GETTING THE FULL BRUNT OF THE ARCTIC OUTBREAK IS LOWER. && .AVIATION... AS DISCUSSED ABOVE...PV ANOMALY MOVING SOUTH WILL BRING A LIGHT SNOW INTO ERN SD AND WRN MN. THIS WILL HAVE THE BIGGEST IMPACT ON THE KFSD TAF WHERE VSBYS COULD BRIEFLY FALL BELOW 3SM...SIMILAR TO WHAT IS OCCURRING AT THIS TIME IN ND. WOULD ALSO EXPECT CIGS BLO 3000 FT WITH AS LOW AS 1500 FT POSSIBLE FOR A COUPLE OF HOURS DURING THE AFTERNOON. KHON MAY SEE SOME LIGHT SNOW BUT EXPECT CONDITIONS TO STAY MVFR AND MOST BE AN IMPACT ON CIGS AND NOT VSBYS. SIMILARLY KSUX MAY SEE A BRIEF PERIOD OF LIGHT SNOW AND LOWER CIGS LATE THIS AFTERNOON AND INTO THE EVENING BUT GENERALLY SHOULD BE VFR. && .FSD WATCHES/WARNINGS/ADVISORIES... SD...NONE. MN...NONE. IA...NONE. NE...NONE. && $$ MG sd AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MORRISTOWN TN 901 PM EST SUN JAN 21 2007 .DISCUSSION...RADAR SHOWS PRECIP EXITING OUR FORECAST AREA TO THE EAST. RUC MODEL SUGGESTS THIS TREND WILL CONTINUE OVERNIGHT. WILL UPDATE ZONES TO REMOVE EVENING WORDING AND DRAMATICALLY LOWER POPS. INCLINED TO NOT COMPLETELY REMOVE POPS HOWEVER AS SOME UPSTREAM REDEVELOPMENT CANNOT BE RULED OUT. CURRENT TEMPS APPEAR REASONABLE BASED ON LATEST MODEL GUIDANCE. && .PRELIMINARY POINT TEMPS/POPS... CHATTANOOGA AIRPORT, TN 41 52 32 48 29 / 20 20 10 10 0 KNOXVILLE MCGHEE TYSON AIRPORT, TN 38 50 31 46 28 / 20 20 20 10 0 OAK RIDGE, TN 38 50 31 45 28 / 20 20 20 10 0 TRI CITIES AIRPORT, TN 36 48 28 41 24 / 20 20 20 20 0 && .MRX WATCHES/WARNINGS/ADVISORIES... NC...NONE. TN...NONE. VA...NONE. && $$ LCM tn AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE MILWAUKEE/SULLIVAN WI 324 PM CST TUE JAN 23 2007 .DISCUSSION...FORECAST FOCUS REMAINS ON PCPN CHANCES WITH SERIES OF DISTURBANCES IN NW FLOW PATTERN. IN THE SHORT TERM...WATER VAPOR IMAGERY SHOWING DISTINCT SHRT WAVE AT 20Z JUST NORTH OF LAKE ERIE. SFC TROF REFLECTION OF THIS WAVE DROPPING THRU CWA ATTM WITH A FEW BANDS OF FLURRIES WHICH SHOULD EXIT SRN CWA BY 00Z. BACK EDGE OF LO STRATUS DECK...WHICH SHOWS VERY WELL IN MODIS 1KM SNOW/ICE IMAGE AT 1915Z...TIMED TO CLEAR MSN AROUND 06Z AND MKE BY 09Z. RUC APPEARS TO HAVE BEST HANDLE ON THIS TREND...WITH CLOUDS HOLDING TEMPS UP FOR THE EVENING...THEN FALLING OFF RAPIDLY OVERNIGHT WITH CLEARING SKIES AND FRESH SNOW COVER REACHING MOS LOWS BY SUNRISE. NAM AND GFS TIME NEXT WAVE IN THE SERIES THRU STATE WED AFTERNOON/EVENING. LACK OF DEEP MOISTURE WILL AGAIN ONLY BRING ANOTHER ROUND OF FLURRIES WITH THIS WAVE. 850 MB TEMPS DIP TO -14C TO -18C BY THUR MORNING...SO HAVE GONE WITH COLDER GFS MOS NUMBERS FOR WED NGT LOWS. WAA BEGINS THUR NGT AND KICKS IN FULL ON FRIDAY. 290K ISENTROPIC SURFACE FORECASTS ON BOTH NAM AND GFS SHOW DECENT ISENTROPIC ADIABATIC OMEGA CROSSING CWA FRIDAY BETWEEN 12Z AND 18Z. CONDENSATION PRESSURE DEFICITS FALL BELOW 100 MB MAINLY TO OUR NORTH...WITH FCST SOUNDINGS AGAIN DEPICTING LACK OF DEEP MOISTURE FOR MEASURABLE PCPN. SOUNDINGS DO SATURATE BELOW 800 MB FRI AFTERNOON SO SOME LIGHT PCPN POSSIBLE FROM LO STRATUS DECK...WITH FLURRIES LIKELY AS WET BULB TEMPS REMAIN BLO 0C...BUT SUCH A QUICK HIT WILL LEAVE OUT MENTION FOR NOW. IN THE EXTENDED...12Z GFS SHOWING A MUCH MORE VIGOROUS VORTICITY MAXIMA FOR SAT/SAT NGT THAT NEARLY CLOSES OFF AT 500 MB JUST TO OUR EAST. DPROG/DT OF PREVIOUS GFS RUNS FOR 00Z SUN JAN 28TH SHOWS THIS NEWER SOLUTION TO BE AN OUTLIER...AND NOT SUPPORTED BY 12Z ECMWF OR CANADIAN. WILL CONTINUE TREND OF BRINGING FLURRIES ACROSS CWA WITH THESE MOISTURE STARVED TROFS. WITH APEX OF WESTERN 500 MB RIDGING EXTENDING WELL NORTH INTO NRN CANADA...REINFORCING SHOTS OF COLD AIR BEHIND EACH WAVE WILL KEEP TEMPS BELOW NORMAL EARLY NEXT WEEK. WILL TREND TEMPS A NOTCH COLDER THAN 12Z HPC GUIDANCE TOWARDS 12Z MEX NUMBERS. && .MKX WATCHES/WARNINGS/ADVISORIES... NONE. && $$ REM wi