Forecast Discussions mentioning any of "HRRR" "RR" "RUC13" "RUC" received at GSD on 01/21/12


AREA FORECAST DISCUSSION
NWS DENVER/BOULDER CO
1225 PM MST THU JAN 19 2012 .UPDATE... && .SHORT TERM...ALL HILITES HAVE EITHER BEEN CANCELLED OR EXPIRED. WILL STILL BE LOOKING AT POSSIBLE HIGH WINDS AGAIN IN THE FOOTHILLS TONIGHT BUT MAY END UP BEING MORE LOCALIZED. MOISTURE DEPTH IN THE MOUNTAINS OVER NEXT 24 HOURS LOOKS RATHER SHALLOW SO WILL LEAN TOWARDS NO HILITES WITH JUST LIGHTER SNOW AMOUNTS. GIVEN THE INCREASING WINDS OVER THE PASSES MAY STILL NEED AN ADVISORY. STAY TUNED FOR AFTERNOON UPDATES. .AVIATION...NO CHANGES PER 18Z TAF WITH AN EASTERLY COMPONENT OF THE WINDS AT ALL LOCAL TERMINALS. BJC COULD SHOW MORE WESTERLY TONIGHT AS NEXT MOUNTAIN WAVE DECENDS THE HILL. && .PREV DISCUSSION... /ISSUED 1006 AM MST THU JAN 19 2012/ UPDATE... SHORT TERM...HAVE ALREADY CANCELLED THE BLIZZARD WARNING FOR THE MOUNTAINS PER OBSERVATIONS AND WEB CAMS. STILL SOME LIGHT SNOW AND GUSTY WINDS BUT CERTAINLY NOTHING WIDESPREAD. ALSO CANCELLED THE HIGH WIND WARNING FOR ZONES 38 AND 39 AS MOUNTAIN WAVE HAS MOVED BACK UP THE HILL AND SURFACE GRADIENT HAS RELAXED. WIND GUSTS GENERALLY UNDER 50 MPH. THERE IS SOME MORE POTENTIAL FOR HIGH WINDS AGAIN TONIGHT IN THE FOOTHILLS AND WILL LOOK AT SOME MORE DATA BEFORE MAKING A DECISION. WILL MOVE LIKELY LET THE REMAINDER OF THE HIGH WIND WARNING EXPIRE AT NOON. THE ZONE 31 WINTER STORM WARNING DOESN`T LOOK GOOD AT THE MOMENT WITH VERY LITTLE SNOW ONGOING BUT THIS SHOULD CHANGE LATER TODAY AND TONIGHT. HAVE WORDED THE WSW ACCORDINGLY WITHOUT ACTUALLY CANCELLING IT. AVIATION...SURFACE WINDS AT LOCAL TERMINALS GENERALLY SOUTHEAST AND WILL PLAY THE PERSISTENCE FOR MUCH OF THE DAY. BJC MAY SEE SOME WESTERLIES TONIGHT BUT A LITTLE SURPRISED THEY DIDN`T BLOW MUCH LAST NIGHT. PREV DISCUSSION... /ISSUED 352 AM MST THU JAN 19 2012/ SHORT TERM...A STRONG NORTHWESTERLY FLOW ALOFT WILL CONTINUE OVER THE CWFA TODAY AND TONIGHT. STRONG WINDS HAVE NOT BEEN AS WIDESPREAD THIS MORNING AS THE MDLS HAD SUGGESTED. THE STRONGEST WINDS APPEARED TO HAVE OCCUR PRIOR TO MIDNIGHT. ALTHOUGH THE JET MAX HAS SHIFTED TO THE NORTH AND EAST...THE SHEAR APPEARS TO HAVE LESSENED THE IMPACT OF THE MOUNTAIN WAVE SO FAR THIS MORNING. IF WE GET ANY MORE STRONG WINDS IT WILL LIKELY OCCUR PRIOR TO 15Z THIS MORNING. IF IT DOES NOT MATERIALIZE BY THAT TIME...THEN THE DAY SHIFT CAN CANCEL THE HIGH WIND WARNING. THE SAME CAN BE SAID FOR THE BLIZZARD WARNING. LGT SNOW HAS DEVELOPED IN THE MOUNTAINS OVERNIGHT AND STRONG WINDS APPEAR TO BE IMPACTING TRAVEL NEAR THE EISENHOWER TUNNEL. THE BLIZZARD CONDITIONS WILL BE MORE WIDESPREAD ABOVE TIMBERLINE. THOSE WINDS ARE STILL EXPECTED TO DECREASE IN MAGNITUDE BY THIS AFTERNOON. ADDITIONAL HIGHLIGHTS MAY BE NECESSARY FOR ZONE 33 AND 34 THIS AFTN AND TNGT. WILL LET THE CURRENT HIGHLIGHT RUN ITS COURSE. NOT SURE THE SNOW WILL BE ENUF TO WARRANT A WINTER STORM WARNING VS A WINTER WEATHER ADVISORY FOR SNOW AND BLOWING SNOW. THE MDLS APPEAR TO HIT THE MOUNTAINS NORTH OF INTERSTATE 70 THE HARDEST. THE WINTER STORM WARNING FOR ZONE 31 STILL LOOKS ON TRACK AND ZONE 33 WILL GET SOME DECENT SNOWFALL AS WELL. THE BEST POTENTIAL FOR SNOW WILL BE TONIGHT AS THE MOISTURE WEST OF THE CONTINENTAL DIVIDE DEEPENS AND THE MID LEVEL LAPSE RATES IMPROVE. NAM12 SPATIAL CROSS-SECTIONS KEEP AN 80 KTS CROSS- MOUNTAIN COMPONENT OF 80 KTS AROUND 600 MB LATE THIS AFTN AND TONIGHT. THE WAVE AMPLICATION OVERNIGHT APPEARS FAIRLY LIMITED SO DO NOT ANTICIPATE HIGH WINDS IN THE FOOTHILLS AS MUCH TONIGHT. AS FOR THE NORTHEAST PLAINS...IT WILL BE DRY WITH TEMPERATURES IN THE MID 50S TO LOWER 60S... MILDEST NEAR THE FOOTHILLS. OVERALL ONLY MINOR ADJUSTMENTS IN THE SHORT TERM. LONG TERM...STRONG WESTERLY FLOW ALOFT WILL CONTINUE TO TRANSPORT PACIFIC MOISTURE ACROSS THE WESTERN U.S. THROUGH THE WEEKEND. THE NEXT WRINKLE IN THE FLOW ALOFT WILL MOVE ACROSS THE STATE TONIGHT AND FRIDAY. THE MOISTURE EMBEDDED IN THE STRONG WESTERLY FLOW ALOFT WILL PRODUCE A ROUND OF OROGRAPHIC SNOW. LAPSE RATES WILL BE AROUND 5-6 C/KM...NOT THAT GREAT BUT NOT BAD EITHER. BEST SNOW ON FRIDAY WILL OCCUR OVER WESTERN JACKSON COUNTY WHERE LOCALLY A FOOT OF NEW SNOW IS POSSIBLE. LESSER AMOUNTS ARE EXPECTED TO THE SOUTH OVER THE MOUNTAINS OF GRAND AND JACKSON COUNTIES. THIS SYSTEM IS PRIMARILY AN OROGRAPHIC SNOW PRODUCER. THE MOUNTAIN VALLEYS WILL SEE A FEW STRAY SNOW SHOWERS OFF THE MOUNTAINS. FOR THE FRONT RANGE AND EASTERN PLAINS...DRY AND MILD CONDITIONS WILL PREVAIL. WILL SEE A BREAK IN THE SNOW FRIDAY NIGHT AND SATURDAY. SLIGHT RIDGING WILL OCCUR DUE TO THE NEXT SHORT WAVE TROUGH NEARING THE ROCKIES. THIS NEXT SYSTEM WILL MOVE ACROSS THE STATE SATURDAY NIGHT...WITH SNOW STARTING OVER NORTH CENTRAL COLORADO LATE SATURDAY AFTERNOON. THIS WAVE IS STRONGER THAN THURSDAY NIGHT/FRIDAY`S SYSTEM. IN ADDITION...LAPSE RATES WILL BE 7-8 C/KM SATURDAY NIGHT. ALL OF THIS WILL PRODUCE A PERIOD OF MODERATE TO HEAVY OROGRAPHIC SATURDAY NIGHT. WILL LIKELY NEED WINTER WEATHER HIGHLIGHTS AS THIS SYSTEM NEARS. WOULD EXPECT THE FAVORED OROGRAPHIC SLOPES TO PICK UP 1-2 FEET OF SNOW. MOST OF THE SNOW WILL AGAIN BE OROGRAPHICALLY DRIVEN. THERE WILL BE A BETTER CHANCE FOR SNOW IN THE MOUNTAINS VALLEYS DUE TO BETTER INSTABILITY. WILL NOT RULE OUT THE CHANCE OF A FEW LIGHT SNOW SHOWERS OVER THE PLAINS EITHER. ANY PRECIPITATION HERE WILL BE LIGHT. AFTER A MILD SATURDAY OVER NORTHEAST COLORADO WHERE HIGHS WILL BE IN THE 50S...COOLER AIR WILL MOVE IN BEHIND THE SYSTEM FOR SUNDAY WITH HIGHS IN THE 40S. PROGRESSIVE WEATHER PATTER WILL CONTINUE THROUGH THE EARLY PART OF NEXT WEEK. RIDGING ON MONDAY WILL BE FOLLOWED BY A TROUGH ON TUESDAY. THEN ANOTHER RIDGE TO AFFECT THE AREA LATE WEDNESDAY AND INTO THURSDAY. WILL KEEP POPS IN THE MOUNTAINS EACH DAY DUE TO THE SOMEWHAT MOIST WESTERLY FLOW AND ALSO DUE TO TIMING UNCERTAINTIES WITH THESE SYSTEMS. THE ENERGY WITH THE SYSTEM ON TUESDAY LOOKS LIKE IT WILL SPLIT AND MOVE AROUND COLORADO. THIS WILL KEEP MOUNTAIN SNOWFALL AMOUNTS ON THE LIGHTER SIDE. FOR THE PLAINS...OTHER THAN LOW POPS FOR THE SYSTEM MONDAY NIGHT TUESDAY WILL KEEP THE FORECAST DRY. HIGHS WILL BE NEAR NORMAL AFTER THE TROUGH PASSAGE TUESDAY...OTHERWISE ABOVE NORMAL TEMPERATURES ARE EXPECTED FOR NORTHEAST COLORADO. AVIATION...WIND WILL CONTINUE TO BE AN ISSUE...ESPECIALLY AT KBJC AND KDEN THIS MORNING. AT KDEN WILL CONTINUE WITH A WESTERLY WIND THIS MORNING UNTIL AROUND 15Z THEN IT APPEAR TO WEAKEN AND BECOME MORE SWLY. NONE OF THE MDLS HAVE HANDLED THE WIND PATTERN VERY WELL THIS MORNING. I WILL BE FOLLOWING THE RUC BOUNDARY LAYER WINDS THIS MORNING. IF THE SFC TROUGH SITS ALONG THE FRONT RANGE THIS AFTN...THEN SOME SORT OF ELY WIND COMPONENT IS STILL POSSIBLE. AS FOR KBJC...WINDS HAVE BEEN SLOW TO MATERIALIZE THIS MORNING. WILL KEEP THE STRONGER GUSTS IN THE TAF UNTIL 15Z THEN DECREASE IT THEREAFTER. && .BOU WATCHES/WARNINGS/ADVISORIES...NONE && $$ SHORT TERM...ENTREKIN LONG TERM....KRIEDERMAN AVIATION...ENTREKIN
AREA FORECAST DISCUSSION
NWS DENVER/BOULDER CO
1006 AM MST THU JAN 19 2012 .UPDATE... && .SHORT TERM...HAVE ALREADY CANCELLED THE BLIZZARD WARNING FOR THE MOUNTAINS PER OBSERVATIONS AND WEB CAMS. STILL SOME LIGHT SNOW AND GUSTY WINDS BUT CERTAINLY NOTHING WIDESPREAD. ALSO CANCELLED THE HIGH WIND WARNING FOR ZONES 38 AND 39 AS MOUNTAIN WAVE HAS MOVED BACK UP THE HILL AND SURFACE GRADIENT HAS RELAXED. WIND GUSTS GENERALLY UNDER 50 MPH. THERE IS SOME MORE POTENTIAL FOR HIGH WINDS AGAIN TONIGHT IN THE FOOTHILLS AND WILL LOOK AT SOME MORE DATA BEFORE MAKING A DECISION. WILL MOVE LIKELY LET THE REMAINDER OF THE HIGH WIND WARNING EXPIRE AT NOON. THE ZONE 31 WINTER STORM WARNING DOESN`T LOOK GOOD AT THE MOMENT WITH VERY LITTLE SNOW ONGOING BUT THIS SHOULD CHANGE LATER TODAY AND TONIGHT. HAVE WORDED THE WSW ACCORDINGLY WITHOUT ACTUALLY CANCELLING IT. .AVIATION...SURFACE WINDS AT LOCAL TERMINALS GENERALLY SOUTHEAST AND WILL PLAY THE PERSISTENCE FOR MUCH OF THE DAY. BJC MAY SEE SOME WESTERLIES TONIGHT BUT A LITTLE SURPRISED THEY DIDN`T BLOW MUCH LAST NIGHT. && .PREV DISCUSSION... /ISSUED 352 AM MST THU JAN 19 2012/ SHORT TERM...A STRONG NORTHWESTERLY FLOW ALOFT WILL CONTINUE OVER THE CWFA TODAY AND TONIGHT. STRONG WINDS HAVE NOT BEEN AS WIDESPREAD THIS MORNING AS THE MDLS HAD SUGGESTED. THE STRONGEST WINDS APPEARED TO HAVE OCCUR PRIOR TO MIDNIGHT. ALTHOUGH THE JET MAX HAS SHIFTED TO THE NORTH AND EAST...THE SHEAR APPEARS TO HAVE LESSENED THE IMPACT OF THE MOUNTAIN WAVE SO FAR THIS MORNING. IF WE GET ANY MORE STRONG WINDS IT WILL LIKELY OCCUR PRIOR TO 15Z THIS MORNING. IF IT DOES NOT MATERIALIZE BY THAT TIME...THEN THE DAY SHIFT CAN CANCEL THE HIGH WIND WARNING. THE SAME CAN BE SAID FOR THE BLIZZARD WARNING. LGT SNOW HAS DEVELOPED IN THE MOUNTAINS OVERNIGHT AND STRONG WINDS APPEAR TO BE IMPACTING TRAVEL NEAR THE EISENHOWER TUNNEL. THE BLIZZARD CONDITIONS WILL BE MORE WIDESPREAD ABOVE TIMBERLINE. THOSE WINDS ARE STILL EXPECTED TO DECREASE IN MAGNITUDE BY THIS AFTERNOON. ADDITIONAL HIGHLIGHTS MAY BE NECESSARY FOR ZONE 33 AND 34 THIS AFTN AND TNGT. WILL LET THE CURRENT HIGHLIGHT RUN ITS COURSE. NOT SURE THE SNOW WILL BE ENUF TO WARRANT A WINTER STORM WARNING VS A WINTER WEATHER ADVISORY FOR SNOW AND BLOWING SNOW. THE MDLS APPEAR TO HIT THE MOUNTAINS NORTH OF INTERSTATE 70 THE HARDEST. THE WINTER STORM WARNING FOR ZONE 31 STILL LOOKS ON TRACK AND ZONE 33 WILL GET SOME DECENT SNOWFALL AS WELL. THE BEST POTENTIAL FOR SNOW WILL BE TONIGHT AS THE MOISTURE WEST OF THE CONTINENTAL DIVIDE DEEPENS AND THE MID LEVEL LAPSE RATES IMPROVE. NAM12 SPATIAL CROSS-SECTIONS KEEP AN 80 KTS CROSS- MOUNTAIN COMPONENT OF 80 KTS AROUND 600 MB LATE THIS AFTN AND TONIGHT. THE WAVE AMPLICATION OVERNIGHT APPEARS FAIRLY LIMITED SO DO NOT ANTICIPATE HIGH WINDS IN THE FOOTHILLS AS MUCH TONIGHT. AS FOR THE NORTHEAST PLAINS...IT WILL BE DRY WITH TEMPERATURES IN THE MID 50S TO LOWER 60S... MILDEST NEAR THE FOOTHILLS. OVERALL ONLY MINOR ADJUSTMENTS IN THE SHORT TERM. LONG TERM...STRONG WESTERLY FLOW ALOFT WILL CONTINUE TO TRANSPORT PACIFIC MOISTURE ACROSS THE WESTERN U.S. THROUGH THE WEEKEND. THE NEXT WRINKLE IN THE FLOW ALOFT WILL MOVE ACROSS THE STATE TONIGHT AND FRIDAY. THE MOISTURE EMBEDDED IN THE STRONG WESTERLY FLOW ALOFT WILL PRODUCE A ROUND OF OROGRAPHIC SNOW. LAPSE RATES WILL BE AROUND 5-6 C/KM...NOT THAT GREAT BUT NOT BAD EITHER. BEST SNOW ON FRIDAY WILL OCCUR OVER WESTERN JACKSON COUNTY WHERE LOCALLY A FOOT OF NEW SNOW IS POSSIBLE. LESSER AMOUNTS ARE EXPECTED TO THE SOUTH OVER THE MOUNTAINS OF GRAND AND JACKSON COUNTIES. THIS SYSTEM IS PRIMARILY AN OROGRAPHIC SNOW PRODUCER. THE MOUNTAIN VALLEYS WILL SEE A FEW STRAY SNOW SHOWERS OFF THE MOUNTAINS. FOR THE FRONT RANGE AND EASTERN PLAINS...DRY AND MILD CONDITIONS WILL PREVAIL. WILL SEE A BREAK IN THE SNOW FRIDAY NIGHT AND SATURDAY. SLIGHT RIDGING WILL OCCUR DUE TO THE NEXT SHORT WAVE TROUGH NEARING THE ROCKIES. THIS NEXT SYSTEM WILL MOVE ACROSS THE STATE SATURDAY NIGHT...WITH SNOW STARTING OVER NORTH CENTRAL COLORADO LATE SATURDAY AFTERNOON. THIS WAVE IS STRONGER THAN THURSDAY NIGHT/FRIDAY`S SYSTEM. IN ADDITION...LAPSE RATES WILL BE 7-8 C/KM SATURDAY NIGHT. ALL OF THIS WILL PRODUCE A PERIOD OF MODERATE TO HEAVY OROGRAPHIC SATURDAY NIGHT. WILL LIKELY NEED WINTER WEATHER HIGHLIGHTS AS THIS SYSTEM NEARS. WOULD EXPECT THE FAVORED OROGRAPHIC SLOPES TO PICK UP 1-2 FEET OF SNOW. MOST OF THE SNOW WILL AGAIN BE OROGRAPHICALLY DRIVEN. THERE WILL BE A BETTER CHANCE FOR SNOW IN THE MOUNTAINS VALLEYS DUE TO BETTER INSTABILITY. WILL NOT RULE OUT THE CHANCE OF A FEW LIGHT SNOW SHOWERS OVER THE PLAINS EITHER. ANY PRECIPITATION HERE WILL BE LIGHT. AFTER A MILD SATURDAY OVER NORTHEAST COLORADO WHERE HIGHS WILL BE IN THE 50S...COOLER AIR WILL MOVE IN BEHIND THE SYSTEM FOR SUNDAY WITH HIGHS IN THE 40S. PROGRESSIVE WEATHER PATTER WILL CONTINUE THROUGH THE EARLY PART OF NEXT WEEK. RIDGING ON MONDAY WILL BE FOLLOWED BY A TROUGH ON TUESDAY. THEN ANOTHER RIDGE TO AFFECT THE AREA LATE WEDNESDAY AND INTO THURSDAY. WILL KEEP POPS IN THE MOUNTAINS EACH DAY DUE TO THE SOMEWHAT MOIST WESTERLY FLOW AND ALSO DUE TO TIMING UNCERTAINTIES WITH THESE SYSTEMS. THE ENERGY WITH THE SYSTEM ON TUESDAY LOOKS LIKE IT WILL SPLIT AND MOVE AROUND COLORADO. THIS WILL KEEP MOUNTAIN SNOWFALL AMOUNTS ON THE LIGHTER SIDE. FOR THE PLAINS...OTHER THAN LOW POPS FOR THE SYSTEM MONDAY NIGHT TUESDAY WILL KEEP THE FORECAST DRY. HIGHS WILL BE NEAR NORMAL AFTER THE TROUGH PASSAGE TUESDAY...OTHERWISE ABOVE NORMAL TEMPERATURES ARE EXPECTED FOR NORTHEAST COLORADO. AVIATION...WIND WILL CONTINUE TO BE AN ISSUE...ESPECIALLY AT KBJC AND KDEN THIS MORNING. AT KDEN WILL CONTINUE WITH A WESTERLY WIND THIS MORNING UNTIL AROUND 15Z THEN IT APPEAR TO WEAKEN AND BECOME MORE SWLY. NONE OF THE MDLS HAVE HANDLED THE WIND PATTERN VERY WELL THIS MORNING. I WILL BE FOLLOWING THE RUC BOUNDARY LAYER WINDS THIS MORNING. IF THE SFC TROUGH SITS ALONG THE FRONT RANGE THIS AFTN...THEN SOME SORT OF ELY WIND COMPONENT IS STILL POSSIBLE. AS FOR KBJC...WINDS HAVE BEEN SLOW TO MATERIALIZE THIS MORNING. WILL KEEP THE STRONGER GUSTS IN THE TAF UNTIL 15Z THEN DECREASE IT THEREAFTER. && .BOU WATCHES/WARNINGS/ADVISORIES... HIGH WIND WARNING UNTIL NOON MST TODAY FOR COZ035-036. WINTER STORM WARNING UNTIL 5 PM MST FRIDAY FOR COZ031. && $$ SHORT TERM...ENTREKIN LONG TERM....KRIEDERMAN AVIATION...ENTREKIN
AREA FORECAST DISCUSSION
NWS DENVER CO
352 AM MST THU JAN 19 2012 .SHORT TERM...A STRONG NORTHWESTERLY FLOW ALOFT WILL CONTINUE OVER THE CWFA TODAY AND TONIGHT. STRONG WINDS HAVE NOT BEEN AS WIDESPREAD THIS MORNING AS THE MDLS HAD SUGGESTED. THE STRONGEST WINDS APPEARED TO HAVE OCCUR PRIOR TO MIDNIGHT. ALTHOUGH THE JET MAX HAS SHIFTED TO THE NORTH AND EAST...THE SHEAR APPEARS TO HAVE LESSENED THE IMPACT OF THE MOUNTAIN WAVE SO FAR THIS MORNING. IF WE GET ANY MORE STRONG WINDS IT WILL LIKELY OCCUR PRIOR TO 15Z THIS MORNING. IF IT DOES NOT MATERIALIZE BY THAT TIME...THEN THE DAY SHIFT CAN CANCEL THE HIGH WIND WARNING. THE SAME CAN BE SAID FOR THE BLIZZARD WARNING. LGT SNOW HAS DEVELOPED IN THE MOUNTAINS OVERNIGHT AND STRONG WINDS APPEAR TO BE IMPACTING TRAVEL NEAR THE EISENHOWER TUNNEL. THE BLIZZARD CONDITIONS WILL BE MORE WIDESPREAD ABOVE TIMBERLINE. THOSE WINDS ARE STILL EXPECTED TO DECREASE IN MAGNITUDE BY THIS AFTERNOON. ADDITIONAL HIGHLIGHTS MAY BE NECESSARY FOR ZONE 33 AND 34 THIS AFTN AND TNGT. WILL LET THE CURRENT HIGHLIGHT RUN ITS COURSE. NOT SURE THE SNOW WILL BE ENUF TO WARRANT A WINTER STORM WARNING VS A WINTER WEATHER ADVISORY FOR SNOW AND BLOWING SNOW. THE MDLS APPEAR TO HIT THE MOUNTAINS NORTH OF INTERSTATE 70 THE HARDEST. THE WINTER STORM WARNING FOR ZONE 31 STILL LOOKS ON TRACK AND ZONE 33 WILL GET SOME DECENT SNOWFALL AS WELL. THE BEST POTENTIAL FOR SNOW WILL BE TONIGHT AS THE MOISTURE WEST OF THE CONTINENTAL DIVIDE DEEPENS AND THE MID LEVEL LAPSE RATES IMPROVE. NAM12 SPATIAL CROSS-SECTIONS KEEP AN 80 KTS CROSS- MOUNTAIN COMPONENT OF 80 KTS AROUND 600 MB LATE THIS AFTN AND TONIGHT. THE WAVE AMPLICATION OVERNIGHT APPEARS FAIRLY LIMITED SO DO NOT ANTICIPATE HIGH WINDS IN THE FOOTHILLS AS MUCH TONIGHT. AS FOR THE NORTHEAST PLAINS...IT WILL BE DRY WITH TEMPERATURES IN THE MID 50S TO LOWER 60S... MILDEST NEAR THE FOOTHILLS. OVERALL ONLY MINOR ADJUSTMENTS IN THE SHORT TERM. .LONG TERM...STRONG WESTERLY FLOW ALOFT WILL CONTINUE TO TRANSPORT PACIFIC MOISTURE ACROSS THE WESTERN U.S. THROUGH THE WEEKEND. THE NEXT WRINKLE IN THE FLOW ALOFT WILL MOVE ACROSS THE STATE TONIGHT AND FRIDAY. THE MOISTURE EMBEDDED IN THE STRONG WESTERLY FLOW ALOFT WILL PRODUCE A ROUND OF OROGRAPHIC SNOW. LAPSE RATES WILL BE AROUND 5-6 C/KM...NOT THAT GREAT BUT NOT BAD EITHER. BEST SNOW ON FRIDAY WILL OCCUR OVER WESTERN JACKSON COUNTY WHERE LOCALLY A FOOT OF NEW SNOW IS POSSIBLE. LESSER AMOUNTS ARE EXPECTED TO THE SOUTH OVER THE MOUNTAINS OF GRAND AND JACKSON COUNTIES. THIS SYSTEM IS PRIMARILY AN OROGRAPHIC SNOW PRODUCER. THE MOUNTAIN VALLEYS WILL SEE A FEW STRAY SNOW SHOWERS OFF THE MOUNTAINS. FOR THE FRONT RANGE AND EASTERN PLAINS...DRY AND MILD CONDITIONS WILL PREVAIL. WILL SEE A BREAK IN THE SNOW FRIDAY NIGHT AND SATURDAY. SLIGHT RIDGING WILL OCCUR DUE TO THE NEXT SHORT WAVE TROUGH NEARING THE ROCKIES. THIS NEXT SYSTEM WILL MOVE ACROSS THE STATE SATURDAY NIGHT...WITH SNOW STARTING OVER NORTH CENTRAL COLORADO LATE SATURDAY AFTERNOON. THIS WAVE IS STRONGER THAN THURSDAY NIGHT/FRIDAY`S SYSTEM. IN ADDITION...LAPSE RATES WILL BE 7-8 C/KM SATURDAY NIGHT. ALL OF THIS WILL PRODUCE A PERIOD OF MODERATE TO HEAVY OROGRAPHIC SATURDAY NIGHT. WILL LIKELY NEED WINTER WEATHER HIGHLIGHTS AS THIS SYSTEM NEARS. WOULD EXPECT THE FAVORED OROGRAPHIC SLOPES TO PICK UP 1-2 FEET OF SNOW. MOST OF THE SNOW WILL AGAIN BE OROGRAPHICALLY DRIVEN. THERE WILL BE A BETTER CHANCE FOR SNOW IN THE MOUNTAINS VALLEYS DUE TO BETTER INSTABILITY. WILL NOT RULE OUT THE CHANCE OF A FEW LIGHT SNOW SHOWERS OVER THE PLAINS EITHER. ANY PRECIPITATION HERE WILL BE LIGHT. AFTER A MILD SATURDAY OVER NORTHEAST COLORADO WHERE HIGHS WILL BE IN THE 50S...COOLER AIR WILL MOVE IN BEHIND THE SYSTEM FOR SUNDAY WITH HIGHS IN THE 40S. PROGRESSIVE WEATHER PATTER WILL CONTINUE THROUGH THE EARLY PART OF NEXT WEEK. RIDGING ON MONDAY WILL BE FOLLOWED BY A TROUGH ON TUESDAY. THEN ANOTHER RIDGE TO AFFECT THE AREA LATE WEDNESDAY AND INTO THURSDAY. WILL KEEP POPS IN THE MOUNTAINS EACH DAY DUE TO THE SOMEWHAT MOIST WESTERLY FLOW AND ALSO DUE TO TIMING UNCERTAINTIES WITH THESE SYSTEMS. THE ENERGY WITH THE SYSTEM ON TUESDAY LOOKS LIKE IT WILL SPLIT AND MOVE AROUND COLORADO. THIS WILL KEEP MOUNTAIN SNOWFALL AMOUNTS ON THE LIGHTER SIDE. FOR THE PLAINS...OTHER THAN LOW POPS FOR THE SYSTEM MONDAY NIGHT TUESDAY WILL KEEP THE FORECAST DRY. HIGHS WILL BE NEAR NORMAL AFTER THE TROUGH PASSAGE TUESDAY...OTHERWISE ABOVE NORMAL TEMPERATURES ARE EXPECTED FOR NORTHEAST COLORADO. && .AVIATION...WIND WILL CONTINUE TO BE AN ISSUE...ESPECIALLY AT KBJC AND KDEN THIS MORNING. AT KDEN WILL CONTINUE WITH A WESTERLY WIND THIS MORNING UNTIL AROUND 15Z THEN IT APPEAR TO WEAKEN AND BECOME MORE SWLY. NONE OF THE MDLS HAVE HANDLED THE WIND PATTERN VERY WELL THIS MORNING. I WILL BE FOLLOWING THE RUC BOUNDARY LAYER WINDS THIS MORNING. IF THE SFC TROUGH SITS ALONG THE FRONT RANGE THIS AFTN...THEN SOME SORT OF ELY WIND COMPONENT IS STILL POSSIBLE. AS FOR KBJC...WINDS HAVE BEEN SLOW TO MATERIALIZE THIS MORNING. WILL KEEP THE STRONGER GUSTS IN THE TAF UNTIL 15Z THEN DECREASE IT THEREAFTER. && .BOU WATCHES/WARNINGS/ADVISORIES... HIGH WIND WARNING UNTIL NOON MST TODAY FOR COZ035-036-038-039. BLIZZARD WARNING UNTIL NOON MST TODAY FOR COZ033-034. WINTER STORM WARNING UNTIL 5 PM MST FRIDAY FOR COZ031. && $$ SHORT TERM...COOPER LONG TERM....MEIER AVIATION...COOPER
AREA FORECAST DISCUSSION
NWS GRAND JUNCTION CO
1003 PM MST WED JAN 18 2012 .AVIATION /FOR 06Z TAF ISSUANCE/... MODERATE TO SEVERE MECHANICAL TURBULENCE IS EXPECTED ACROSS THE REGION FOR THE NEXT 24 HOURS...ESPECIALLY NEAR THE DIVIDE. EXPECT IFR CONDITIONS TO DEVELOP ALONG THE NRN DIVIDE AS SNOW INCREASES ALONG THE PARK AND GORE RANGES OVERNIGHT AND CONTINUES INTO THURSDAY. VFR CONDITIONS WILL PERSIST AT ALL TAF SITES. HOWEVER AREAS OF LIGHT SNOW WILL BE IN THE VICINITY OF KASE AND KEGE. THERE IS A SLIGHT CHANCE THAT 5SM -SN BRN025 CONDITIONS WILL OCCUR AT THESE AIRPORTS. && .PREV DISCUSSION /ISSUED 711 PM MST WED JAN 18 2012/... UPDATE... THE DEEPER MOISTURE PLUME REMAINS NORTH OF COLORADO BUT EXPECTED TO SAG SOUTHWARD LATER THIS EVENING. SNOW HAS NOT STARTED OVER THE WEST SIDE OF THE DIVIDE JUST YET...BUT MODELS INDICATE SNOW WILL BE EXPANDING SOUTHWARD OVER THE NRN DIVIDE AND NEAR VAIL PASS BETWEEN 8 PM AND 11 PM THIS EVENING. A LITTLE CONCERNED THAT WEST SOUTHWEST FLOW AT MOUNTAIN TOP MAY SHELTER VAIL PASS AND SNOW MAY BE HARD PRESS TO DEVELOP THERE. THE LATEST HRRR MODEL KEPT THE SNOW EAST OF VAIL PASS. WILL SEE WHAT EVOLVES DURING THE NEXT 3 TO 6 HOURS. PREV DISCUSSION /ISSUED 323 PM MST WED JAN 18 2012/... SHORT TERM /TONIGHT THROUGH FRIDAY/... THE PACIFIC MOISTURE TAP HAS OPENED UP...EXTENDING FROM THE PACIFIC NORTHWEST BACK TO HAWAII AND BEYOND ON WATER VAPOR SATELLITE IMAGES. A SERIES OF SHORTWAVE TROUGHS ACROSS THE NORTHERN PACIFIC OCEAN WILL TAP THIS MOISTURE AS THEY MOVE INLAND ACROSS THE NORTHERN AND CENTRAL ROCKIES IN THE DAYS AHEAD. THE FIRST SHORTWAVE WAS MOVING ACROSS OREGON/WASHINGTON BUT WILL GET STRETCHED AND WEAKEN BY THE TIME IT ZIPS ACROSS THE NORTH TONIGHT. REGIONAL RADAR SHOWING PRECIP ACROSS SRN ID/NRN NV/NW UT...AND THIS DEEPER MOISTURE IS EXPECTED TO STEADILY ADVANCE INTO NE UT/WRN CO TONIGHT CAUSING SNOW TO INCREASE ACROSS THE NORTHERN AND CENTRAL MTNS. THIS COUPLED WITH STRONG WINDS WILL PRODUCE HAZARDOUS WINTER CONDITIONS IN THE ELKHEAD/PARK/GORE/FLATTOP/ELK MTNS TONIGHT INTO THU MORNING. MAIN FORCING LOOKS TO BE WARM ADVECTION AND PERSISTENT AND MOIST WESTERLY OROGRAPHIC FLOW SLAMMING INTO THE MTNS. MODELS INDICATE 700 MB /ROUGHLY 10K FEET ELEVATION/ WESTERLY WINDS IN THE 40-55 KT RANGE NORTH OF I-70. LOOKS LIKE A DOWNTURN IN SNOW ACTIVITY LATER BY THU AFTERNOON IN BETWEEN SHORTWAVES...WITH THE NEXT AND STRONGER WAVE AFFECTING THE FORECAST AREA THU NIGHT INTO FRI. IF CURRENT MODELS ARE CORRECT...SNOW COULD LAST LONGER INTO FRI THAN CURRENT WINTER HIGHLIGHT SUGGEST. BUT...WITH TIMING OFTEN PROBLEMATIC IN THESE FAST ZONAL FLOW REGIMES...WILL NOT DO ANY ADJUSTING AT THIS TIME. THE EASTERN UINTA MTNS ARE EXPECTED TO GENERALLY BE SHADOWED BY THE HIGHER MTNS TO THEIR WEST WITH ONLY SOME LIGHT ACCUMULATIONS. ADDED A BLIZZARD WARNING FOR CO ZONE 10 /GORE AND ELK MTNS/ TO THE MIX OF WINTER HIGHLIGHTS FOR THE NORTHERN CO MTNS TONIGHT AND THU MORNING. MOST CONCERNED ABOUT VAIL PASS AND SURROUNDING AREAS WHERE BLOWING SNOW AND STRONG WINDS SHOULD POSE A SIGNIFICANT DANGER TO TRAVEL OVER I-70 TONIGHT. LOWER AND MORE WESTERN VALLEY AREAS OF ZONE 10 NOT LIKELY TO BE AS AFFECTED. THANKS FOR THE COORDINATION WFO BOU AND PUB. THERE IS OVERLAP OF PRODUCTS AT THIS TIME BUT EXPECT THE WIND HIGHLIGHTS TO BE CANCELLED AS THE SNOW/BLIZZARD HIGHLIGHTS GO INTO EFFECT THIS EVENING. AN AREA THAT BEARS WATCHING IS THE STEAMBOAT VALLEY. NAM FORECAST SOUNDINGS HAVE THE LOWER ATMOSPHERE BECOMING NEARLY SATURATED AND ISOTHERMAL IN THE LOWER END OF THE FAVORABLE SNOW GROWTH REGIME FOR A TIME TONIGHT...OFTEN FAVORABLE FOR ENHANCED SNOW PRODUCTION. RAISED POPS TO LIKELY TONIGHT AND ADDED A COUPLE INCHES OF ACCUMULATION FOR THE VALLEY FROM ABOUT HAYDEN EAST TO STEAMBOAT. STEAMBOAT VALLEY COULD SEE ACCUMULATING SNOW AGAIN THU NIGHT/FRI MORNING. LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/... ACTIVE PATTERN WILL CONTINUE AS THE MOIST AND ENERGETIC FLOW OVER THE REGION PERSISTS THROUGH THE LONG TERM PERIOD. A COUPLE OF SHORTWAVE TROUGHS WILL MOVE ACROSS THE WESTERN CONUS BEGINNING ON SATURDAY. EACH WAVE WILL BRING A ROUND OF SNOW...ESPECIALLY FOR THE MOUNTAINS...AS IT SWEEPS OVER EASTERN UTAH AND WESTERN COLORADO. THE NORTH WILL GENERALLY BE FAVORED. DUE TO THE FAST PACIFIC FLOW FEEL THAT MODEL TIMING WILL CONTINUE TO EVOLVE SOMEWHAT...BUT IN GENERAL MODELS SHOW EXCELLENT AGREEMENT. THE PERIOD BEGINS IN A LULL AS A FLAT SHORTWAVE RIDGE PASSES FRIDAY NIGHT. THEN PRECIPITATION WILL SPREAD IN ON SATURDAY AS THIS PERIOD/S FIRST TROUGH APPROACHES AND MOVES OVERHEAD SAT NIGHT. THE PATTERN BECOMES MORE AMPLIFIED BUT STILL PROGRESSIVE AS THIS TROUGH DIGS INTO THE CENTRAL CONUS...AND A RIDGE FOLLOWS ACROSS THE WEST. SNOW WILL GRADUALLY WIND DOWN ON SUN/SUN NIGHT AS THE RIDGE AXIS PASSES OVERHEAD. THE NEXT WAVE APPROACHES ON MONDAY WITH THE TROUGH AXIS REACHING WESTERN COLORADO MONDAY EVENING. AGAIN MODEL CONSISTENCY QUITE HIGH. AFTER THIS WAVE MODELS INDICATE A LESS PROGRESSIVE FLOW AS HIGH PRESSURE BUILDS OFF THE SOUTHERN CALIFORNIA COAST...AND LOW PRESSURE OVER THE GREAT LAKES TO THE SOUTHERN PLAINS. NORTHWEST FLOW WILL DEVELOP OVER OUR AREA AND PERSIST THROUGH THE END OF THE PERIOD. EXPECT THAT THE NORTHERN DIVIDE AREA WILL CONTINUE TO SEE SNOW SHOWERS AT TIMES IN THIS FAVORABLE NORTHWEST FLOW. && .GJT WATCHES/WARNINGS/ADVISORIES... CO...HIGH WIND WARNING UNTIL NOON MST THURSDAY FOR ZONE 012. WIND ADVISORY UNTIL NOON MST THURSDAY FOR ZONES 018-019. WINTER STORM WARNING UNTIL 9 AM MST FRIDAY FOR ZONE 004. BLIZZARD WARNING UNTIL NOON MST THURSDAY FOR ZONE 010. WINTER WEATHER ADVISORY UNTIL 9 AM MST FRIDAY FOR ZONE 013. UT...NONE. && $$ SHORT TERM...JAD LONG TERM....EH AVIATION.....PF
AREA FORECAST DISCUSSION
NWS ALBANY NY
442 PM EST THU JAN 19 2012 .SYNOPSIS... HIGH PRESSURE WILL CONTINUE TO LINGER OVER THE REGION INTO THE AFTERNOON...THEN A FAST MOVING CLIPPER TYPE SYSTEM WILL IMPACT OUR REGION LATE BY THIS EVENING...BRINGING SOME LIGHT SNOW AND SNOW SHOWERS. A MORE SIGNIFICANT STORM MAY IMPACT OUR REGION LATE FRIDAY NIGHT THROUGH SATURDAY AS IT MOVES FROM THE TENNESSEE VALLEY ACROSS THE MIDDLE ATLANTIC REGION. && .NEAR TERM /UNTIL 6 AM FRIDAY MORNING/... AS OF 1230 PM...HAD TO BACK OFF THE ARRIVAL OF CLOUDS AND ANY SNOW PER SURFACE OBS. RADARS INDICATED THE SNOW SHOWERS WERE JUST ENTERING BUFFALO. THE HRRR EXPERIMENTAL MODEL DOES INDICATE RETURNS OF NEAR 20 DBZ NOT REACHING ALBANY UNTIL 00Z. PREVIOUS PACKAGE HAD IT ARRIVING A FEW HOURS. THE AIR IS VERY DRY(AS WAS OUR 12Z RAOB) AND WILL LIKELY CAUSE THE INITIAL SURGE OF MOISTURE TO EVAPORATE. NO CHANGE ON HIGH TEMPERATURES BASED ON THIS 12Z RAOB WHICH WHEN FULLY MIXING THE LOW LEVEL INVERSION GAVE ALBANY A HIGH OF 26. WE ARE ALREADY 23...SO UPPER 20S LOOKS HERE...LOWER 30S SOUTH AND 20-25 MOST OTHER PLACES...EXCEPT TEENS FAR NORTH AND HIGHEST ELEVATION. ALL PRECIPITATION SHOULD BE SNOW WITH THIS SYSTEM...BUT FINAL SNOWFALL AMOUNTS STILL NOT ETCHED IN STONE. FOR NOW...LEFT CURRENT THINKING FROM TONIGHT ALONE AS WE CONTINUE TO ACCESS ON THE NEW INCOMING DATA. FOR THE NEXT SEVERAL HOURS...LOOK FOR SUNSHINE TO BE FOLLOWED BY RAPID INCREASING CLOUDS FROM THE WEST AND ANY SNOW LIKELY TO HOLD OFF CERTAINLY FROM THE HUDSON VALLEY EAST...POSSIBLY REACHING OUR SOUTHERN ADIRONDACKS BY 400 PM. ********PREVIOUS NEAR TERM FORECAST************** AS OF 950 AM EST...A CLIPPER LOW CONTINUES TO QUICKLY APPROACH FROM SOUTHEASTERN ONTARIO THIS AFTERNOON. THE HIGH CLOUDS IN ADVANCE OF A WEAK WARM FRONT CONTINUES TO OVERSPREAD THE REGION. THE DENSER CANOPY OF CLOUDS IS OVER WRN NY. WE RETOOLED THE CLOUD TRENDS AND THE POP/WX TRENDS BASED ON THE LATEST NAM/HRRR. THE WARM ADVECTION LIGHT SNOW/SNOW SHOWERS DOESN/T LOOK LIKE IT WILL MOVE INTO MOST OF THE REGION UNTIL AFTER 23Z /6 PM/. THE BEST CHANCE OF SOME SNOW IN THE LATE AFTERNOON IS OVER THE WRN DACKS. WE INCREASED THE POPS TO LIKELY THERE. THE 12Z KALB SOUNDING IS VERY DRY...AND IT WILL TAKE A LITTLE TIME TO SATURATE. THINKING REMAINS FOR THE HIGHEST TOTALS ACROSS THE SRN DACKS...SRN GREENS...NRN BERKS...AND PARTS OF THE MOHAWK VALLEY WITH 2-4 INCHES. AN INCH OR TWO IS POSSIBLE FROM THE CAPITAL REGION NORTHWARD INTO THE LAKE GEORGE REGION AND WEST INTO THE ERN CATSKILLS. AN INCH OR LESS IS POSSIBLE IN THE MID HUDSON VALLEY...SRN TACONICS SOUTHWARD. && .SHORT TERM /6 AM FRIDAY MORNING THROUGH SATURDAY NIGHT/... A BRIEF VISIT BY HIGH PRESSURE ON FRIDAY...THEN ANOTHER FAST MOVING SYSTEM WILL AFFECT THE REGION LATE FRIDAY NIGHT AND SATURDAY. THIS LOW PRESSURE SYSTEM IS TRACKING FROM THE TENNESSEE VALLEY AND WILL HAVE MORE MOISTURE TO WORK WITH. IT IS NEVERTHELESS AN OPEN WAVE WITH NOT A LOT OF DYNAMICS. FOR ONCE...THIS SYSTEM LOOKS TO BE PRETTY MUCH ALL SNOW ACROSS OUR REGION. THERE MIGHT BE A LITTLE SPOTTY FREEZING DRIZZLE AT THE TAIL END OF THE STORM AS THE MODELS INDICATE THE CLOUDS WILL LOOSE THEIR ICE AT THAT POINT. THEREFORE WE CONTINUE OUR THINKING THAT THIS WILL NOT BE A MAJOR STORM BUT LOOKS TO BRING ADVISORY LEVEL SNOW SOUTH OF CAPITAL DISTRICT. THE SNOW LOOKS TO SPREAD INTO THE REGION FROM SOUTHWEST TO NORTHEAST PRIOR TO OR AROUND DAYBREAK ON SATURDAY AS THE SURFACE LOW TRACKS WELL SOUTH OF THE MASON DIXON LINE. FAIRLY GOOD ISENTROPIC LIFT AND A DECENT (BUT NOT IMPRESSIVE) FRONTOGENTIC BAND WILL PASS ACROSS OUR SOUTHERN AREAS. THERE MIGHT BE A PRETTY SHARP CUTOFF IN THE SNOW WELL NORTH OF THE CAPITAL DISTRICT. FOR NOW...WE HAVE CATEGORICAL POPS SOUTH OF THE CAPITAL DISTRICT...LIKELY CAPITAL DISTRICT AND CHANCES NORTH. SNOW WILL LIKELY BECOME MODERATE FOR A AWHILE FROM JUST SOUTH OF ALBANY...BUT THIS WILL BE ANOTHER FAST MOVING SYSTEM WHICH WILL HELP PREVENT HEAVIER AMOUNTS. LIQUID TO SNOW RATIOS LOOK A LITTLE HIGHER THAN THE CLIMATOLOGICAL 13:1...ESPECIALLY FROM ALBANY NORTHWARD. THAT SAID...THE 18Z NAM CAME IN WITH SLIGHTLY HIGHER AMOUNTS OF QPF AGAIN AND WOULD IMPLY ADVISORY LEVELS RIGHT UP TO THE CAPITAL DISTRICT. FOR NOW THOUGH...WE WILL CONTINUE WITH THE PREVIOUS THINKING OF A 2-4 INCH SNOWFALL GREATER CAPITAL REGION...MOHAWK VALLEY...NORTHERN BERKSHIRES AND SOUTHERN VERMONT. FURTHER SOUTH...4-6 INCHES CAN BE EXPECTED ACROSS THE CATSKILLS...MUCH OF THE MID HUDSON VALLEY...SOUTHERN BERKSHIRES...AND LITCHFIELD COUNTY. THE SNOW LOOKS TO WIND DOWN...AGAIN POSSIBLY ENDING AS LITTLE FREEZING DRIZZLE DURING THE AFTERNOON ON SATURDAY. (WE DID NOT MENTION ANY FREEZING DRIZZLE IN THE GRIDS SINCE THE CONFIDENCE OF THIS HAPPENING WAS STILL RATHER LOW). HIGH TEMPERATURES LOOK TO BE 25-30 MOST PLACES ON SATURDAY...20 TO 25 WELL NORTH OF ALBANY. HIGH PRESSURE LOOKS TO BUILD BACK FROM EASTERN CANADA SATURDAY NIGHT INTO SUNDAY. IF WE CLEAR OUT SATURDAY NIGHT AND GET A DECENT SNOWPACK...TEMPERATURES COULD GET QUITE COLD BY SUNDAY MORNING. WE FEEL PRETTY CONFIDENT THE SKY WILL CLEAR...AT LEAST NORTH OF ALBANY. HOWEVER THE SNOW PACK WILL BE LESS IN THAT VICINITY. FOR NOW...FOLLOWED A BLEND OF THE MET/MAV GUIDANCE WHICH GAVE US COLD TEMPS UP NORTH WITH LOTS OF SINGLE NUMBERS...TEENS SOUTH. && .LONG TERM /SUNDAY THROUGH THURSDAY/... AN AREA OF HIGH PRESSURE WILL MOVE FROM JUST NORTH OF THE REGION ON SUNDAY MORNING TO JUST EAST OF NORTHERN MAINE BY SUNDAY EVENING. ENOUGH SUBSIDENCE WILL BE IN PLACE OVER OUR REGION TO ALLOW FOR A DRY DAY ON SUNDAY WITH PARTLY TO MOSTLY SUNNY SKIES AND TEMPS CLOSE TO SEASONAL AVERAGES /GENERALLY UPPER 20S TO MIDDLE 30S/. CLOUDS WILL BEGIN TO INCREASE ON SUNDAY EVENING AS A STRONG STORM SYSTEM DEEPENS OVER THE NORTHERN GREAT LAKES. A SOUTHERLY LOW LEVEL JET OF 40-50 KTS AROUND 850 HPA WITH BEGIN TO TRANSPORT WARMER AIR ALOFT INTO THE REGION. SFC TEMPS WON/T DROP OFF MUCH AT ALL. FOR NOW...WE HAVE TEMPS BASICALLY STEADY OVERNIGHT...ALTHOUGH THE LOW MAY WIND UP ACTUALLY BEING IN THE LATE EVENING WITH TEMPS RISING OVERNIGHT. THE SOUTHERLY FLOW WILL ALLOW FOR SOME WEAK ISENTROPIC LIFT AND MAY ALLOW FOR A PERIOD OF LIGHT PRECIPITATION OVERNIGHT. WITH SFC TEMPS BELOW FREEZING IN MANY PLACES...THE PRECIP WILL BEGIN AS A WINTRY MIX. THE LATEST 12 UTC GFS BUFR SOUNDINGS SHOW THAT A SNOW/SLEET MIX MAY QUICKLY CHANGE TO RAIN OR FREEZING RAIN DEPENDING ON THE BOUNDARY LAYER TEMPS. THIS FZRA MAY HANG ON FOR A FEW HOURS EVEN INTO MONDAY MORNING /MAINLY ACROSS THE SOUTHERN GREENS OR DACKS/ BEFORE TEMPS WARM UP ENOUGH EVERYWHERE FOR JUST PLAIN RAIN SHOWERS. TEMPS SHOULD WARM UP WELL INTO THE 40S IN MOST PLACES AS THE STRONG LOW LIFTS INTO SOUTHERN CANADA. THE STORM/S COLD FRONT SHOULD PASS THROUGH THE REGION DURING THE EVENING HOURS ON MONDAY. THIS WILL ALLOW TEMPS TO FALL DOWN SOMEWHAT AND END THE THREAT FOR WIDESPREAD PRECIP. TEMPS WILL BE COOLER FOR TUESDAY...BUT STILL A LITTLE ABOVE NORMAL...WITH MAX TEMPS NEAR 40 FOR THE CAPITAL REGION. IT WILL GENERALLY BE DRY FOR TUESDAY INTO WEDNESDAY AS WEAK HIGH PRESSURE PASSES OVER THE AREA. TEMPS ON WED WILL CONTINUE TO BE A LITTLE ABOVE NORMAL FOR MOST AREAS...WITH UPPER 30S IN THE CAPITAL REGION. THE MODELS DISAGREE SOMEWHAT FOR THURSDAY. THE LATEST 12 UTC ECMWF SHOWS A WEAK NORTHERN STREAM CLIPPER STORM MOVING ACROSS THE AREA...WHILE THE 12 UTC GFS SHOWS A LITTLE DEEPER LOW MOVING TO THE SOUTH OF THE REGION. IN EITHER SCENARIO...WE WOULD HAVE A CHANCE OF SOME LIGHT SNOWFALL...SO WILL GO WITH CHC POPS FOR LIGHT SNOW...ALTHOUGH QPF WILL DEPEND ON JUST HOW THE STORM TRACKS. WITH THIS BEING VERY FAR OUT...IT/S BOUND TO CHANGE SEVERAL TIMES WITH SUBSEQUENT MODEL RUNS...SO IT/S A LOW CONFIDENCE FORECAST AT THIS TIME. FOR NOW...WITH THE EXPECTED CLOUDS/PRECIP...WILL FORECAST TEMPS A LITTLE CLOSER TO SEASONAL NORMALS...WITH LOWER TO MIDDLE 30S FOR MANY AREAS. && .AVIATION /21Z THURSDAY THROUGH TUESDAY/... VFR CONDITIONS WILL PERSIST INTO THE EVENING HOURS AT ALL OUR TAFS. LOW PRESSURE NORTH OF THE GREAT LAKES REGION...WILL DRAG A COLD FRONT THROUGH LATER TONIGHT. THERE MIGHT BE A BURST OF SNOW WITH THIS FEATURE...BUT IT SHOULD NOT LAST LONG AND IFR CONDITIONS LOOK TO BE BRIEF IF AT ALL. KGFL HAS THE BEST CHANCE OF EXPERIENCING IFR BUT EVEN HERE FOR NOW...WE KEPT THEM (AS ALL OF THE OTHER TAFS) MVFR AS CONFIDENCE REMAINS TOO LOW TO INCLUDE. (UNDER 50 PERCENT). THIS LOW PRESSURE SYSTEM WILL BE QUICK MOVING...WITH ONLY VCSH EXPECTED BY 08Z/KALB...09Z/KGFL AND 10Z/KPOU. ANY REMAIN SNOW SHOWERS WILL BE SHORT LIVED AS SUBSIDENCE BEHIND THE COLD FRONT ACCOMPANYING THE SYSTEM WILL MOVE OVER THE AREA MID TO LATE FRIDAY MORNING. THIS SUBSIDENCE WILL ALSO HELP DECREASE CLOUD COVER. WINDS WILL BE OUT OF THE SOUTH AT 3-8 KTS...WITH KALB EXPERIENCING SOME GUSTS TO 18 KTS. OVERNIGHT...WINDS WILL SHIFT BEHIND THE COLD FRONT FROM SOUTH TO W SOMETIME BETWEEN 08Z AND 10Z THEN INCREASE IN THE MID TO LATE MORNING AND THROUGH THE DAY. OUTLOOK... FRI...VFR...NO SIG WX. SAT...SUB-VFR...CIG. SNOW..ESPECIALLY FROM ALBANY SOUTH. SUN...VFR...NO SIG WX. MON-TUE...SUB-VFR...CIG. CHC -RA/-SN. && .HYDROLOGY... NO MAJOR PROBLEMS ARE EXPECTED ON THE MAIN STEM RIVERS THROUGH THE WEEKEND AS ANY PRECIPITATION WHICH FALLS WILL BE IN THE FORM OF SNOW. A CLIPPER TYPE SYSTEM WHICH IS EXPECTED TO BRIEF BURST OF SNOW TO MANY LOCATIONS TONIGHT. QPF AMOUNTS WILL BE LESS THAN A QUARTER OF AN INCH AND SINCE IT WILL BE ALL SNOW NO IMPACT ON ANY WATERSHEDS. A MORE SIGNIFICANT STORM IS EXPECTED TO TRACK FROM THE TENNESSEE VALLEY TOWARD THE MIDDLE ATLANTIC COAST BRINGING A GENERALLY LIGHT TO MODERATE SNOWFALL TO THE REGION LATE FRIDAY NIGHT INTO SATURDAY WITH THE POTENTIAL FOR HEAVIER SNOW ACROSS THE HIGHER TERRAIN SOUTH AND EAST OF CAPITAL DISTRICT. SINCE AGAIN IT LOOKS TO BE ALL SNOW...NO IMPACT ON ANY OUR WATERSHEDS. ICE FORMATION ON BODIES OF WATER IS EXPECTED TO INCREASE AGAIN THROUGH THE END OF THE WEEK AS COLD AIR WILL BE IN PLACE ACROSS THE REGION. FOR DETAILS ON SPECIFIC AREA RIVERS AND LAKES...INCLUDING OBSERVED AND FORECAST RIVER STAGES AND LAKE ELEVATIONS...PLEASE VISIT THE ADVANCED HYDROLOGIC PREDICTION SERVICE /AHPS/ GRAPHS ON OUR WEBSITE. && .ALY WATCHES/WARNINGS/ADVISORIES... CT...NONE. NY...NONE. MA...NONE. VT...NONE. && $$ SYNOPSIS...HWJIV NEAR TERM...HWJIV SHORT TERM...HWJIV LONG TERM...FRUGIS AVIATION...KGM HYDROLOGY...HWJIV/GJM
AREA FORECAST DISCUSSION
NWS ALBANY NY
1243 PM EST THU JAN 19 2012 .SYNOPSIS... HIGH PRESSURE WILL CONTINUE TO LINGER OVER THE REGION INTO THE AFTERNOON...THEN A FAST MOVING CLIPPER TYPE SYSTEM WILL IMPACT OUR REGION LATE BY THIS EVENING...BRINGING SOME LIGHT SNOW AND SNOW SHOWERS. A MORE SIGNIFICANT STORM MAY IMPACT OUR REGION LATE FRIDAY NIGHT THROUGH SATURDAY AS IT MOVES FROM THE TENNESSEE VALLEY ACROSS THE MIDDLE ATLANTIC REGION. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... AS OF 1230 PM...HAD TO BACK OFF THE ARRIVAL OF CLOUDS AND ANY SNOW PER SURFACE OBS. RADARS INDICATED THE SNOW SHOWERS WERE JUST ENTERING BUFFALO. THE HRRR EXPERIMENTAL MODEL DOES INDICATE RETURNS OF NEAR 20 DBZ NOT REACHING ALBANY UNTIL 00Z. PREVIOUS PACKAGE HAD IT ARRIVING A FEW HOURS. THE AIR IS VERY DRY(AS WAS OUR 12Z RAOB) AND WILL LIKELY CAUSE THE INITIAL SURGE OF MOISTURE TO EVAPORATE. NO CHANGE ON HIGH TEMPERATURES BASED ON THIS 12Z RAOB WHICH WHEN FULLY MIXING THE LOW LEVEL INVERSION GAVE ALBANY A HIGH OF 26. WE ARE ALREADY 23...SO UPPER 20S LOOKS HERE...LOWER 30S SOUTH AND 20-25 MOST OTHER PLACES...EXCEPT TEENS FAR NORTH AND HIGHEST ELEVATION. ALL PRECIPITATION SHOULD BE SNOW WITH THIS SYSTEM...BUT FINAL SNOWFALL AMOUNTS STILL NOT ETCHED IN STONE. FOR NOW...LEFT CURRENT THINKING FROM TONIGHT ALONE AS WE CONTINUE TO ACCESS ON THE NEW INCOMING DATA. FOR THE NEXT SEVERAL HOURS...LOOK FOR SUNSHINE TO BE FOLLOWED BY RAPID INCREASING CLOUDS FROM THE WEST AND ANY SNOW LIKELY TO HOLD OFF CERTAINLY FROM THE HUDSON VALLEY EAST...POSSIBLY REACHING OUR SOUTHERN ADIRONDACKS BY 400 PM. ********PREVIOUS NEAR TERM FORECAST************** AS OF 950 AM EST...A CLIPPER LOW CONTINUES TO QUICKLY APPROACH FROM SOUTHEASTERN ONTARIO THIS AFTERNOON. THE HIGH CLOUDS IN ADVANCE OF A WEAK WARM FRONT CONTINUES TO OVERSPREAD THE REGION. THE DENSER CANOPY OF CLOUDS IS OVER WRN NY. WE RETOOLED THE CLOUD TRENDS AND THE POP/WX TRENDS BASED ON THE LATEST NAM/HRRR. THE WARM ADVECTION LIGHT SNOW/SNOW SHOWERS DOESN/T LOOK LIKE IT WILL MOVE INTO MOST OF THE REGION UNTIL AFTER 23Z /6 PM/. THE BEST CHANCE OF SOME SNOW IN THE LATE AFTERNOON IS OVER THE WRN DACKS. WE INCREASED THE POPS TO LIKELY THERE. THE 12Z KALB SOUNDING IS VERY DRY...AND IT WILL TAKE A LITTLE TIME TO SATURATE. THINKING REMAINS FOR THE HIGHEST TOTALS ACROSS THE SRN DACKS...SRN GREENS...NRN BERKS...AND PARTS OF THE MOHAWK VALLEY WITH 2-4 INCHES. AN INCH OR TWO IS POSSIBLE FROM THE CAPITAL REGION NORTHWARD INTO THE LAKE GEORGE REGION AND WEST INTO THE ERN CATSKILLS. AN INCH OR LESS IS POSSIBLE IN THE MID HUDSON VALLEY...SRN TACONICS SOUTHWARD. && .SHORT TERM /6 PM THIS EVENING THROUGH SATURDAY/... A BRIEF VISIT BY HIGH PRESSURE ON FRIDAY...THEN ANOTHER FAST MOVING SYSTEM WILL AFFECT THE REGION LATE FRIDAY NIGHT AND SATURDAY. THIS LOW PRESSURE SYSTEM WILL BE BETTER ORGANIZED AND ALSO TRACK TO THE SOUTH OF THE REGION...MOVING OFF THE MID ATLANTIC COAST ON SATURDAY. HEAVIER SNOW POSSIBLE WITH THIS SYSTEM...BUT NO MAJOR STORM IS EXPECTED. PRELIMINARY FORECAST SNOWFALL AMOUNTS INDICATE ONE TO FOUR INCHES OF SNOW POSSIBLE ACROSS THE NORTHERN HALF OF THE FORECAST AREA...AND 3 TO 7 INCHES OVER THE SOUTH. HOWEVER...WOULD NOT TAKE MUCH OF A SOUTHWARD SHIFT IN THE TRACK OF THIS LOW PRESSURE SYSTEM TO REDUCE THESE SNOWFALL AMOUNTS SIGNIFICANTLY. SOME MODEL DIFFERENCES EXIST IN TERMS OF TIMING OF THIS EVENT. GFS/ECMWF HAVE SIMILAR TIMING WITH THE SNOW STARTING AROUND OR SHORTLY AFTER MIDNIGHT FRIDAY NIGHT...AND ENDING BY EARLY AFTERNOON SATURDAY. THEN NAM STARTS THE SNOW AROUND SUNRISE ON SATURDAY...AND LINGERS IT INTO EARLY SATURDAY EVENING. FOR NOW HAVE FORECAST CLOSER TO THE FASTER GFS/ECMWF SOLUTIONS. DESPITE THE TIMING DIFFERENCES... MODEL FORECASTS OF SNOWFALL AMOUNTS ARE SIMILAR. STILL COLD THIS PERIOD...HIGHS FRIDAY WILL BE IN THE UPPER TEENS TO LOWER 30S...LOWS FRIDAY NIGHT IN THE SINGLE NUMBERS AND TEENS... HIGHS SATURDAY IN THE 20S. && .LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/... FAST BROAD CYCLONIC FLOW WITH EMBEDDED UPPER IMPULSES WILL CONTINUE TO AFFECT OUR REGION THROUGH THE PERIOD...WITH A RELATIVELY STRONG SYSTEM TO AFFECT THE REGION BETWEEN SUNDAY NIGHT AND MONDAY EVENING. FIRST...SATURDAY NIGHT AND SUNDAY...HIGH PRESSURE WILL CONTROL THE WEATHER WITH LOWS IN THE TEENS...SINGLE NUMBERS IN THE SOUTHERN ADIRONDACKS. HIGHS SUNDAY WITH INCREASING CLOUDS IN THE LOW TO MID 30S...WITH UPPER 20S IN HIGHER ELEVATIONS. STRONG UPPER ENERGY APPROACHES SUNDAY NIGHT...WITH INCREASING WARM ADVECTION AND ISENTROPIC LIFT...AND AREAS OF PRECIPITATION WILL SPREAD ACROSS THE REGION. LOTS OF UNCERTAINTY ON THE TIMING OF WARM AIR ALOFT BUT THE GENERAL CONSENSUS FOR SNOW CHANGING TO MIXED PRECIPITATION VERY LATE SUNDAY NIGHT AND THROUGH MONDAY MORNING. MIXED PRECIPITATION WOULD INCLUDE SOME POSSIBILITIES FOR FREEZING RAIN. BY MONDAY AFTERNOON...MOST AREAS OUTSIDE OF THE SOUTHERN ADIRONDACKS SHOULD SEE A COLD RAIN...WITH SOME MIXED PRECIPITATION POSSIBLY ALL DAY IN THE SOUTHERN ADIRONDACKS. LOWS SUNDAY NIGHT IN THE MID 20S TO NEAR 30...SOME TEENS IN THE SOUTHERN ADIRONDACKS. HIGHS MONDAY IN THE UPPER 30S TO MID 40S...FEW COOLER AREAS IN THE SOUTHERN ADIRONDACKS. CONSIDERABLE SPREAD IN GUIDANCE/ENSEMBLES BEYOND MONDAY NIGHT. SYSTEM MOVES OUT SOME TIME WITHIN THE TIME WINDOW BETWEEN MONDAY AFTERNOON AND TUESDAY MORNING...WITH COLD ADVECTION BEGINNING. PRECIPITATION TRANSITIONS TO SNOW SHOWER ACTIVITY. LOWS MONDAY NIGHT IN THE 20S TO LOWER 30S. DRYING AND CLEARING EITHER LATE MONDAY NIGHT OR TUESDAY...AND REMAINING DRY THROUGH WEDNESDAY. HIGHS TUESDAY IN THE 30S TO LOWER 40S. SOME STRONGER COLD ADVECTION WEDNESDAY WITH HIGHS IN THE MID 30S TO NEAR 40...SOME 20S IN HIGHER ELEVATIONS. && .AVIATION /18Z THURSDAY THROUGH TUESDAY/... VFR CONDITIONS WILL PERSIST THROUGH AT LEAST THE NEXT 6 HOURS AS HIGH PRESSURE SLIDES EASTWARD TOWARD THE CANADIAN MARITIMES. LOW PRESSURE NORTH OF THE GREAT LAKES REGION...WITH A COLD FRONT DRAPING JUST WEST OF THE OHIO RIVER VALLEY...HAS ALREADY STARTED TO SPREAD MID AND HIGH LEVEL CLOUDS INTO EASTERN NY. CLOUDS WILL CONTINUE TO INCREASE AND LOWER THROUGHOUT THE DAY...WITH MVFR CIGS ARRIVING AFTER 00Z/FRIDAY...WHICH WILL BE ACCOMPANIED BY SNOW. KGFL AND KALB COULD SEE A BRIEF PERIOD OF IFR DURING SNOWFALL BETWEEN 00Z AND 06Z...BUT CONFIDENCE IS LOW ON TIMING OF BRIEF IFR CONDITIONS. KGFL AND KALB CAN EXPECT 1 TO 2 INCHES OF SNOWFALL BY EARLY FRIDAY MORNING. KPOU WILL LIKELY SEE LESS THAN ONE INCH. THIS LOW PRESSURE SYSTEM WILL BE QUICK MOVING...WITH ONLY VCSH EXPECTED BY 08Z/KALB...09Z/KGFL AND 10Z/KPOU. ANY REMAIN SNOW SHOWERS WILL BE SHORT LIVED AS SUBSIDENCE BEHIND THE COLD FRONT ACCOMPANYING THE SYSTEM WILL MOVE OVER THE AREA MID TO LATE FRIDAY MORNING. THIS SUBSIDENCE WILL ALSO HELP DECREASE CLOUD COVER. WINDS WILL BE OUT OF THE SOUTH AT 3-8 KTS...WITH KALB EXPERIENCING SOME GUSTS TO 18 KTS. OVERNIGHT...WINDS WILL SHIFT BEHIND THE COLD FRONT FROM SOUTH TO SW-W SOMETIME BETWEEN 08Z AND 10Z THEN INCREASE IN THE MID TO LATE MORNING AND THROUGH THE DAY. OUTLOOK... FRI...VFR...NO SIG WX. SAT...MVFR/IFR...SNOW LIKELY. SUN...VFR...NO SIG WX. MON-TUE...VFR/MVFR/IFR...CHC -RA/-SN. && .HYDROLOGY... NO MAJOR PROBLEMS ARE EXPECTED ON THE MAIN STEM RIVERS THROUGH THE WEEKEND AS ANY PRECIPITATION WHICH FALLS WILL BE IN THE FORM OF SNOW. COLD AND DRY WEATHER WILL PREVAIL THROUGH MOST OF TODAY...FOLLOWED BY A CLIPPER TYPE SYSTEM WHICH IS EXPECTED TO BRING LIGHT SNOW TO THE REGION LATE TODAY AND TONIGHT. A MORE SIGNIFICANT STORM IS EXPECTED TO TRACK FROM THE TENNESSEE VALLEY TOWARD THE MIDDLE ATLANTIC COAST BRINGING A GENERALLY LIGHT TO MODERATE SNOWFALL TO THE REGION LATE FRIDAY NIGHT INTO SATURDAY WITH THE POTENTIAL FOR HEAVIER SNOW ACROSS THE HIGHER TERRAIN SOUTH AND EAST OF CAPITAL DISTRICT. ICE FORMATION ON BODIES OF WATER IS EXPECTED TO INCREASE AGAIN THROUGH THE END OF THE WEEK AS COLD AIR WILL BE IN PLACE ACROSS THE REGION. FOR DETAILS ON SPECIFIC AREA RIVERS AND LAKES...INCLUDING OBSERVED AND FORECAST RIVER STAGES AND LAKE ELEVATIONS...PLEASE VISIT THE ADVANCED HYDROLOGIC PREDICTION SERVICE /AHPS/ GRAPHS ON OUR WEBSITE. && .ALY WATCHES/WARNINGS/ADVISORIES... CT...NONE. NY...NONE. MA...NONE. VT...NONE. && $$ SYNOPSIS...HWJIV/WASULA NEAR TERM...HWJIV/WASULA SHORT TERM...GJM LONG TERM...NAS AVIATION...KGM HYDROLOGY...GJM
AREA FORECAST DISCUSSION
NWS MOUNT HOLLY NJ
347 PM EST THU JAN 19 2012 .SYNOPSIS... HIGH PRESSURE MOVES OFFSHORE TONIGHT AS A LOW PRESSURE SYSTEM TRACKS ACROSS SOUTHEASTERN CANADA. ITS ASSOCIATED COLD FRONT WILL SWING THROUGH OUR AREA LATE TONIGHT. MORE HIGH PRESSURE WILL BUILD INTO THE MID ATLANTIC FOR FRIDAY. OVER THE WEEKEND, LOW PRESSURE WILL DELIVER UNSETTLED WEATHER TO THE REGION SATURDAY, FOLLOWED BY HIGH PRESSURE SETTLING IN FOR SUNDAY. MORE LOW PRESSURE MAY AFFECT OUR AREA EARLY NEXT WEEK. && .NEAR TERM /UNTIL 6 AM FRIDAY MORNING/... THE GFS AND WRF-NMM INITIALIZATION LOOKED PRETTY GOOD OFF OF THE 12Z SOUNDINGS WITH NEITHER MODEL FAVORED. THE ECMWF AND HRRR VERIFIED THE BEST WITH THE QPF GEOGRAPHICAL EXTENT TO OUR WEST AT 18Z AND THE FORMER WAS USED TO FINE TUNE THE WX GRIDS FOR TONIGHT. THE MODELS TRENDED COLDER AND THUS LESS OF A GEOGRAPHICAL MENTION OF RAIN FOR TONIGHT. THERE HAS NOT BEEN MUCH OF A MODEL CHANGE WITH RESPECT TO FORCING AND THE LACK OF MOISTURE WITH WHAT UNDER OTHER CIRCUMSTANCES COULD HAVE BEEN A MORE DYNAMICAL SYSTEM. THE ACTIVE SNOW AREA TO OUR NW IS IN THE EXIT REGION OF A 160KT JET WHICH IS FORECAST TO WEAKEN TONIGHT, BUT STILL WILL PASS ACROSS THE NORTHERN PART OF OUR CWA. THE ISENTROPIC LIFT (AT 280K) AND THETA E ADVT PART OF THIS EVENT IS FORECAST TO PASS OFFSHORE BY 00Z. MOST OF THEIR WORK IS TO TRY TO BRING SOME MSTR INTO OUR CWA, BUT THE SOURCE REGION TO OUR SW IS QUITE DRY. SO WHEN THE EXIT RGN OF THE JET AND THE FCST DEEP LEVEL QVEC CONVERGENCE ARRIVE, THE WAA PART OF THE PROGRAM IS OVER. FOR BETTER OR WORSE THIS DISCONTINUITY GOES A LONG WAY TOWARD GENERATING THE LOW QPF ALL OF THE MODELS ARE FORECASTING. NEVERTHELESS GIVEN THE LAST COUPLE OF FEATURES, WE INCREASED POPS FAR NORTH FOR WATER EQUIVALENTS WHICH WILL PROBABLY BE ONLY SEVERAL HUNDREDTHS. A QUARTER OF AN INCH OR GREATER SNOW FOLLOWED THE .01 QPF OFF THE ECMWF. THE NEXT SLICE DOWN THROUGH THE I95 CORRIDOR WE SUGGEST A DUSTING POSSIBLE BY MORNING. FARTHER SE, WARMER ANTECEDENT SURFACE TEMPS AND LIGHTER INTENSITY MIGHT MIX IN SOME RAIN, BUT REGARDLESS SHOULD RESULT IN NO EXPECTED DUSTINGS. THE MODELS TRY TO SHOW A POSSIBLE SECOND QPF MAX ALONG THE NJ COAST (A COUPLE OF HUNDREDTHS MAYBE) LATE. THIS IS RELATED TO ANOTHER QVEC CONVERGENCE AREA TRYING TO CATCH UP TO THE PRE FRONTAL ENVIRONMENT. REASON FOR A POP IN THE POPS TOWARD MORNING THERE. BECAUSE OF THE SW FLOW AND CLOUDS PRECEDING THE COLD FRONT WE PREFERRED THE SLIGHTLY HIGHER DATASETS FOR MINS. THE OVERALL STRENGTH OF THE FCST LLJ IS ABOUT 5-10 KTS LOWER THAN THE 00Z SOUNDING RUN, SO WE LOWERED LAND BASED GUSTS EAST ABOUT THE SAME AMT. && .SHORT TERM /6 AM FRIDAY MORNING THROUGH 6 PM FRIDAY/... A QUIET AND SEASONABLY COLD DAY IS FORECAST FOR FRIDAY. THE SOUNDING INVERSION NORTHWEST SINKS RATHER QUICKLY SO WE LIMITED THE MENTION OF FLURRIES IN THE POCONOS TO EARLY. THE FORECAST CONVECTIVE TEMPERATURES GET PRETTY HIGH, SO WE ARE NOT EXPECTING MUCH HOME GROWN CUMULUS CLOUDS. BY THE AFTERNOON WE SHOULD START SEEING THE CIRRUS CLOUDS ASSOCIATED WITH THE NEXT SYSTEM. BASED ON THE FORECAST FULL SUN MACROS, THE SLIGHTLY WARMER GFS MOS WAS PREFERRED FOR TEMPERATURES. THERE MAY BE SOME WIND GUSTS IN THE MORNING, BUT OVERALL THE WINDS WILL BE CLOSER TO SEASONAL AVERAGE AND NOT AS ROBUST AS THE PREVIOUS COLD FRONTAL PASSAGE. && .LONG TERM /FRIDAY NIGHT THROUGH THURSDAY/... ACTIVE WEATHER WILL START OFF THE LONG TERM PERIOD AS ORGANIZING LOW PRESSURE TO OUR SOUTHWEST APPROACHES FRIDAY NIGHT AND MOVES OVER THE REGION DURING SATURDAY. MODEL ANALYSIS AND LOOKING AT FCST SOUNDINGS CONTINUE TO DEPICT THIS AS A MIXED PRECIPITATION EVENT WITH AMPLE MOISTURE MOVING OVER THE AREA AND SUFFICIENT COLD AIR IN PLACE AT THE SURFACE TO START THE EVENT. MOST OF THE FORECAST AREA WILL LIKELY SEE LIGHT SNOW AT THE ONSET OF PRECIPITATION DURING THE EARLY MORNING HOURS OF SATURDAY. BUT WITH WARM ADVECTION TAKING PLACE DURING THE COURSE OF SATURDAY, A TRANSITION TO SLEET OR EVEN FREEZING RAIN AND THEN TO RAIN APPEARS PROBABLE FROM LATE MORNING TO AFTERNOON FOR OUR SOUTHERN AND CENTRAL COUNTIES. THE TRANSITION TO WINTRY MIX MAY REACH THE LEHIGH VALLEY, BUT AREAS IN THE POCONOS AND NORTHWEST NJ LOOK TO RECEIVE PRIMARILY SNOW FROM THIS EVENT, WITH SEVERAL INCHES OF ACCUMULATION PROBABLE AT THIS TIME. A WINTER STORM WATCH HAS BEEN ISSUED WITH THIS FORECAST PACKAGE FOR CARBON AND MONROE COUNTIES IN PA AND SUSSEX COUNTY IN NJ AS ACCUMULATIONS RANGING FROM 4 TO 7 INCHES ARE ANTICIPATED AT THIS TIME. THE EURO IS A BIT SLOWER THAN THE GFS WITH THE PASSAGE OF THIS SYSTEM OVER THE REGION, WITH PRECIPITATION PROGGED TO LAST LONGER INTO SATURDAY NIGHT. THE GFS WAS FAVORED A BIT WITH THE FASTER ONSET OF PRECIPITATION WITH THE EVENT, AND ITS ALSO NOTED THAT THE GFS HAS TRENDED COLDER. DURING SUNDAY, STRONG HIGH PRESSURE SPREADS SOUTHWEST FROM EASTERN CANADA AS THE LOW PRESSURE SYSTEM PUSHES EAST AND OUT TO SEA. QUIETER CONDITIONS GENERALLY ARE EXPECTED TO RETURN SUNDAY, ALTHOUGH THE MODELS HINT AT THE POSSIBILITY OF A COLD AIR DAMMING SITUATION DEVELOPING. THE ODDS ON THIS HAPPENING AS EARLY AS SUNDAY ARE NOT GREAT, AND THE SUNDAY POPS WITH THIS FORECAST ARE LOW. ANOTHER LOW PRESSURE SYSTEM IS EXPECTED TO AFFECT OUR FORECAST AREA AS EARLY AS SUNDAY NIGHT IN THE ACTIVE PATTERN. THIS LOW PRESSURE ORGANIZES OVER THE CENTRAL PLAINS STATES DURING SUNDAY AND TRACKS NORTHEASTWARD TO THE GREAT LAKES REGION SUNDAY NIGHT THROUGH MONDAY. ITS ASSOCIATED FRONTS WILL MOVE THROUGH OUR REGION MONDAY AND MONDAY NIGHT. TEMPERATURES AND THERMAL FIELDS GENERALLY ARE MILD ENOUGH TO SUPPORT RAIN WITH THE PASSAGE OF THIS SYSTEM, ALTHOUGH COLD AIR THANKS TO THE RECEDING HIGH TO THE NORTHEAST MAY GENERATE A PERIOD OF SNOW CHANGING TO FREEZING RAIN FOR A WHILE NORTH. THE EURO AGAIN IS SLOWER THAN THE GFS WITH THE PROGRESSION OF THIS SYSTEM THROUGH THE EASTERN STATES. HOWEVER, AT THIS TIME, IT APPEARS THAT THIS SYSTEM PUSHES EAST OF OUR AREA OVERNIGHT MONDAY. AFTER THAT, THE MODELS ARE QUITE DIVERGENT (EVEN WITHIN THEMSELVES FROM RUN TO RUN). && .AVIATION /21Z THURSDAY THROUGH TUESDAY/... THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY AND SURROUNDING AREAS. THE LATEST 18Z TAFS KEEP A VFR FORECAST GOING, BUT CONFIDENCE IS LOWEST AT KABE. A RAPID INCREASE IN MID AND HIGH LEVEL CLOUDINESS WILL CONTINUE THE REST OF THE AFTERNOON. AS THE HIGH MOVES OFFSHORE, THERE WILL BE A WINDOW FOR SOME BREEZINESS AND GUSTS FOR AROUND 15 KT WERE MAINTAINED. FOR TONIGHT, SNOW SHOWERS AND FLURRIES ASSOCIATED WITH AN APPROACHING COLD FRONT WILL WORK THEIR WAY INTO THE TERMINALS. GREATEST CHANCE FOR MVFR AND MAYBE EVEN BRIEFLY VSBY RELATED IFR RESTRICTIONS IS EXPECTED AT LOCAL AIRPORTS NORTH OF A KRDG-KABE- KTTN LINE WHERE FCST MOISTURE IS DEEPEST. SO IF WE ARE TOO OPTIMISTIC ABOUT OUR TERMINALS, KABE IS MOST VULNERABLE. CIGS ARE FORECAST TO LOWER, BUT REMAIN VFR. THE COLD FRONT SHOULD CLEAR THE TERMINALS FROM AROUND 09Z TO 11Z FROM WEST TO EAST AND END ANY SNOW CHANCES. THE GRADIENT BEHIND THE FRONT IS NOT THAT STRONG AND GUSTS WERE ONLY INCLUDED AT OUR TWO WINDIEST AIRPORTS, KPHL AND KACY. VFR CONDITIONS WITH NO CIGS ARE THEN FORECAST TO RETURN DURING THE DAYLIGHT MORNING. OUTLOOK... LOW PRESSURE APPROACHES AND MOVES OVER THE REGION FROM FRIDAY NIGHT THROUGH SATURDAY, BRINGING THE POTENTIAL FOR MIXED WINTRY PRECIPITATION TO THE FORECAST AREA. LOWER CEILINGS AND VISIBILITIES ARE EXPECTED DURING THIS TIMEFRAME. DEPENDING ON HOW QUICKLY THE SYSTEM EXITS THE REGION, LOWER CONDITIONS MAY EXTEND INTO EARLY SUNDAY. THE NEXT LOW PRESSURE SYSTEM THAT MAY AFFECT THE AREA, BRINGING RAIN ALONG WITH LOWERED CEILING AND VISIBILITY VALUES, IS EXPECTED SUNDAY NIGHT TO MONDAY NIGHT. && .MARINE... THE SMALL CRAFT ADVISORY WAS EXTENDED INTO FRIDAY MORNING FOR ALL MARINE AREAS. THE INCREASING SW FLOW SHOULD BRING SMALL CRAFT CONDITIONS TONIGHT. EVEN THOUGH THE WINDS ARE SOUTHWEST, IN THIS INSTANCE IT STILL WILL BE COLDER AIR PASSING OVER WARMER WATER. THERE WILL BE A LULL LATE AS THE COLD FRONT NEARS, BUT THEN COULD BE A COUPLE OF HOUR WINDOW OF OPPORTUNITY FOR MORE SCA CONDITIONS IN THE FRESH COLD AIR ADVECTION BEHIND THE COLD FRONT ON FRIDAY MORNING. AS THE NEXT HIGH PRESSURE SYSTEM THEN NEARS, BOTH WINDS AND SEAS SHOULD DROP BELOW SMALL CRAFT ADVISORY CRITERIA BY THE AFTERNOON. WITH LOW PRESSURE MOVING OVER THE AREA SATURDAY THROUGH SATURDAY NIGHT, REACHING SMALL CRAFT ADVISORY CRITERIA FOR SEAS IS EXPECTED, THANKS TO A PERSISTENT EAST TO NORTHEAST FLOW. THE ELEVATED SEAS IN THE 5 TO 6 FOOT RANGE ON OUR WATERS ARE ANTICIPATED SATURDAY NIGHT THROUGH SUNDAY, AND THE ELEVATED SEAS MAY EXTEND INTO MONDAY WITH THE PASSAGE OF ANOTHER WEATHER SYSTEM. WINDS AND GUSTS MAY OCCASIONALLY REACH ADVISORY LEVELS DURING THIS TIME FRAME. && .PHI WATCHES/WARNINGS/ADVISORIES... PA...WINTER STORM WATCH FROM LATE FRIDAY NIGHT THROUGH SATURDAY EVENING FOR PAZ054-055. NJ...WINTER STORM WATCH FROM LATE FRIDAY NIGHT THROUGH SATURDAY EVENING FOR NJZ001. DE...NONE. MD...NONE. MARINE...SMALL CRAFT ADVISORY FROM 7 PM THIS EVENING TO 11 AM EST FRIDAY FOR ANZ430-431-450>455. && $$ SYNOPSIS...KLINE NEAR TERM...GIGI SHORT TERM...GIGI LONG TERM...DELISI/KLINE AVIATION...DELISI/GIGI/KLINE MARINE...DELISI/GIGI/KLINE
AREA FORECAST DISCUSSION
NWS MOUNT HOLLY NJ
921 AM EST THU JAN 19 2012 .SYNOPSIS... AN AREA OF HIGH PRESSURE OVER THE LOWER HUDSON VALLEY IN NEW YORK STATE WILL MOVE OFF TO THE EAST THROUGH TONIGHT. LOW PRESSURE WILL MOVE ACROSS ONTARIO AND QUEBEC TODAY AND TONIGHT. IT WILL CAUSE A COLD FRONT TO MOVE ACROSS OUR REGION. MORE HIGH PRESSURE WILL SETTLE ACROSS THE AREA FRIDAY AND THEN WITHDRAW EASTWARD FRIDAY NIGHT. ANOTHER LOW PRESSURE SYSTEM WILL BRING MORE UNSETTLED WEATHER TO THE AREA SATURDAY. MORE HIGH PRESSURE WILL FOLLOW FOR SUNDAY. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... THE ESTF UPDATE WAS BASICALLY SOME SMALL POP TWEAKING. TEMPS, DEWS AND WINDS ARE LOOKING GOOD. THE HRRR WAS VERIFYING THE BEST OF THE MODELS (RGEM SECOND) AS TO WHERE THE SNOW WAS REACHING THE GROUND IN THE GREAT LAKES. BASED ON THOSE MODELS AND A QUICK GLANCE AT THE NEW SREF, WE SLOWED THE ARRIVAL OF THE SNOW SLIGHTLY FAR NORTHWEST. AHEAD OF THE SHORT WAVE...SURFACE HIGH PRESSURE WILL CREST OVER THE REGION THIS MORNING...THEN MOVE OFFSHORE THIS AFTERNOON. 0000 UTC SOUNDINGS ACROSS THE AREA WHERE BONE DRY (WITH PRECIPITABLE WATER VALUES NEAR 0.10 INCHES). THE ENTIRE COLUMN IS DRY...AND THE WARM AIR ADVECTION AHEAD OF THE IMPRESSIVE SHORT WAVE WILL GO INTO MOISTENING THE COLUMN. THIS WILL MANIFEST ITSELF AS INCREASING HIGH AND THEN MID LEVEL CLOUDINESS. THE COLUMN COULD MOISTEN IN THE BETTER WARM AIR ADVECTION ENOUGH ACROSS THE LEHIGH VALLEY AND THE SOUTHERN POCONOS FOR SOME FLURRIES LATE...BUT BASED ON HOW DRY THE AIRMASS IS NOW...EVEN THESE LOCATIONS SHOULD STAY DRY THROUGH DUSK. MODEL SOUNDINGS SUGGEST THAT MOS VALUES ARE CLOSE FOR HIGHS...AND A BLEND WAS USED FOR TODAY. AS THE SURFACE HIGH GETS FARTHER EAST THIS MORNING...THE RETURN FLOW INCREASES THIS AFTERNOON. MODEL SOUNDINGS SHOW THE DEPTH OF THE MIXED LAYER WILL BE ENOUGH FOR SOUTHERLY WINDS TO GUST TO 20 MPH THIS AFTERNOON...MAINLY NEAR THE COAST AND IN THE HIGHER TERRAIN. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 AM FRIDAY/... THE MAIN FORECAST PROBLEM FOR TONIGHT INCLUDE PRECIPITATION COVERAGE...SNOW AMOUNTS...AND WHETHER THE LOW LEVEL JET WILL PRODUCE WIND GUSTS NEAR THE COAST AFTER MIDNIGHT. THE APPROACHING SHORT WAVE WILL TRY TO INDUCE A LAYER OF MID LEVEL FRONTOGENETIC FORCING ACROSS CENTRAL AREAS THIS EVENING. THE AIRMASS WILL STILL BE FAIRLY DRY...AS THE WAA INDUCED LIFT NOW AHEAD OF THE SHORT WAVE IS MOSTLY DRY. THE FRONTOGENETIC FORCING APPEARS TO BE MAXIMIZE DURING THE EVENING HOURS ACROSS CENTRAL AND NORTHERN AREAS. IT WOULD APPEAR AS THOUGH THE SOUTH TO SOUTHWEST CROSS BARRIER FLOW ACROSS THE HIGHER TERRAIN WILL HELP SQUEEZE OUT THE AVAILABLE MOISTURE. THE COMBINATION OF LIFT AND SQUEEZING DUE TO OROGRAPHIC EFFECTS SHOULD ALLOW NORTHERN AREAS SEE LIGHT SNOW DEVELOP THIS EVENING. QPF AMOUNTS FOR THIS EVENT ARE RATHER MEAGER...BASED ON WHAT IS OCCURRING UPSTREAM AND THE GENERAL DRYNESS OF THE AIRMASS IN PLACE. RIGHT NOW...IT LOOKS LIKE THE HIGHER TERRAIN OF THE SOUTHERN POCONOS AND NORTHWEST NEW JERSEY. THE BEST DYNAMIC LIFT ASSOCIATED WITH THE SHORT WAVE SHOULD PASS NORTH OF THE AREA...AND BASED ON THE QPF WE COULD SEE AN INCH OR TWO IN THE HIGHER TERRAIN. FURTHER SOUTH...THE SOUTHERN EXTENT OF THE PRECIPITATION BECOMES A BIT MORE NEBULOUS. THE WARM AIR ADVECTION WILL MOISTEN THE COLUMN...BUT ONLY TO A POINT. IT WOULD APPEAR THAT AREAS SOUTH OF AN KMQS-KPHL-KACY LINE MAY BE JUST TOO DRY FOR THE WARM AIR ADVECTION TO BE OF MUCH HELP. IN BETWEEN THE HIGHER TERRAIN AND THE ABOVEMENTIONED LINE...PRECIPITATION CHANCES WERE GRADUATED FROM NORTH TO SOUTH. THE WARM AIR ADVECTION MAY ALSO PLAY HAVOC WITH LIGHT PRECIPITATION TYPE. IN PLACES WHERE PRECIPITATION IS STEADY...THE EVAPORATIVE COOLING SHOULD ALLOW A NEAR ISOTHERMAL PROFILE...AND THE SNOW SHOULD BE THE MAIN PRECIPITATION TYPE. FOR THE LOWER LEHIGH VALLEY THROUGH THE DELAWARE VALLEY INTO CENTRAL NEW JERSEY...THE PRECIPITATION TYPE COULD BE DOMINATED BY PRECIPITATION RATES...AND THE FURTHER SOUTH ONE GOES INTO THE AIRMASS IN PLACES...A MIX OF RAIN COULD BE MORE THE DOMINANT TYPE DUE TO CONTINUED WARM AIR ADVECTION. SINCE TEMPERATURES HAVE BEEN COLD THE PAST DAY OR SO...COLDER SURFACES MAY BE ABLE TO SUPPORT LIGHT SNOW ACCUMULATIONS OUTSIDE OF THE TERRAIN. FOR NOW...HOWEVER...SNOWFALL AMOUNTS APPEAR TO BE LESS THAN AN INCH. THE MAIN THRUST OF WARM AIR ADVECTION INDUCED PRECIPITATION SHOULD EXIT THE AREA AHEAD OF THE COLD FRONT ASSOCIATED WITH THE STRONG SHORT WAVE. AHEAD OF THE FRONT IN THE WARM AIR ADVECTION...MODEL SOUNDINGS ARE SUGGESTING THAT DELAWARE AND COASTAL NEW JERSEY COULD SEE MIXING LAYERS DEEP ENOUGH TO SUPPORT WIND GUSTS TO 35 MPH AS A LOW LEVEL JET CROSSES AREAS LATE THIS EVENING AND OVERNIGHT. AS IS USUALLY THE CASE WITH WARM AIR ADVECTION AND LOWERING INVERSIONS... THE GUSTINESS OF THE WINDS APPEAR TO BE PROBLEMATIC. FOR NOW WIND GUSTS WILL BE KEPT BELOW 35 MPH ALONG THE COAST...AND IN ANY EVENT DO NOT APPEAR TO SUPPORT WIND ADVISORY CRITERIA. TEMPERATURES PROBABLY DROP A BIT THIS EVENING...THEN REMAIN MORE OR LESS STEADY THROUGH THE COLD FRONTAL PASSAGE. SINCE MOS SEEMS TO BE PICKING UP ON THIS...A BLEND OF MOS NUMBERS WAS USED FOR LOWS. && .LONG TERM /FRIDAY THROUGH WEDNESDAY/... FAIR WEATHER IS EXPECTED FRI AS HIGH PRESSURE BUILDS BACK ACROSS THE AREA. A FEW LINGERING NOW SHOWERS MAY CONTINUE EARLY IN THE DAY ACROSS THE SOUTHERN POCONOS. THE NEXT SYSTEM WILL BRING MORE CLOUDS AND PRECIPITATION TO THE AREA SATURDAY INTO SATURDAY NIGHT. IT APPEARS THAT THE NORTHERN AREAS WILL BE COLD ENOUGH FOR (MOSTLY) SNOW AND MAYBE SOME SLEET WITH THE LOW. SOME ACCUMULATIONS WILL OCCUR...MAYBE SEVERAL INCHES...AND WWA FLAGS MAY BE NEEDED IN UPCOMING FCSTS. THE LOW WILL BRING SOME SNOW TO CENTRAL AREAS OF NJ AND METRO PHILADELPHIA TOO...BUT TEMPERATURES MAY WARM ENOUGH TO CAUSE A CHANGE OVER TO RAIN DURING THE DAY...REDUCING THE ACCUMULATIONS. MOSTLY RAIN IS EXPECTED ACROSS THE DELMARVA. THE SYSTEM MOVES TO THE EAST SAT NIGHT AND PRECIPITATION SHOULD END BY SUN MORNING. FAIR WEATHER IS EXPECTED SUN AS HIGH PRESSURE WEDGES DOWN FROM CANADA. ANOTHER LOW WILL DEEPEN ACROSS THE PLAINS AND SEND MORE WARM AIR AND RAIN TO THE AREA MON-TUE. THE LATEST EC IS SLOWER WITH THIS SYSTEM AS COMPARED TO THE GFS...SO WITH THE MODEL DIFFERENCES...FEW CHANGES WERE MADE IN THE TUE OR WED PERIODS OF THE FCST. && .AVIATION /14Z THURSDAY THROUGH MONDAY/... SURFACE HIGH PRESSURE IS ABOUT TO CREST OVER THE REGION... WHICH IS KEEPING A BIT OF A NORTH TO NORTHEAST GRADIENT AHEAD OF THE HIGH...AND THIS IS IN TURN KEEPING WINDS FROM BECOMING LIGHT AND VARIABLE. THIS WILL LIKELY HAPPEN BEFORE SUNRISE. VFR CONDITIONS ARE EXPECTED TODAY...AS HIGH AND MID LEVEL CLOUDINESS INCREASE AND THICKEN. THE LIGHT NORTH TO NORTHEAST GRADIENT EARLY THIS MORNING WILL DIMINISH...AND AS THE SURFACE HIGH GETS OFFSHORE...THE RETURN FLOW INCREASES THIS AFTERNOON. MODEL SOUNDINGS SUGGEST THAT WIND GUSTS TO ABOUT 18 KNOTS ARE POSSIBLE THIS AFTERNOON...AND THE WIND DIRECTION LOOKS TO BE 180-190 DEGREES. THIS MAY HAVE SOME OPERATIONAL IMPACT AT KPHL THIS AFTERNOON...BUT THE GUSTS ARE EXPECTED TO DIMINISH BY 2300 UTC. A COLD FRONT APPROACHING THE REGION THIS AFTERNOON AND EVENING WILL ALLOW LOWER CLOUDS TO DEVELOP AHEAD OF IT. THE COLD FRONT HAS A BAND OF SNOW WITH AND JUST AHEAD OF IT ACROSS THE WESTERN GREAT LAKES EARLY THIS MORNING. IT APPEARS AS THOUGH THE FORCING FOR THE SNOW WILL PASS MAINLY NORTH OF THE AREA TONIGHT...BUT COULD CLIP KABE AND PERHAPS KRDG WITH LIGHT SNOW. THE 0600 UTC INCLUDES MVFR CONDITIONS FOR LIGHT SNOW AT KABE AND HINTS AT THE POTENTIAL FOR KRDG. FURTHER SOUTH...IT IS NOT CLEAR JUST HOW MUCH OF AN IMPACT PRECIPITATION WILL HAVE. THE AIRMASS WILL WARMER AT THE KPHL METRO AIRPORTS...SO THE PRECIPITATION COULD FALL AS RAIN OR SNOW. VFR CONDITIONS WITH THE POSSIBILITY OF LIGHT RAIN AND SNOW IS INDICATED AT KTTN AND KPNE...BUT NO FURTHER SOUTH AND EAST. THE FINAL FORECAST ISSUE FOR TONIGHT IS THE POTENTIAL FOR LOW LEVEL WIND SHEAR. SHORT TERM MODELS SHOW A 40 TO 45 KNOT LOW LEVEL JET IMPACT THE REGION BETWEEN 0300 AND 0900 UTC FRIDAY. THE INVERSION WILL LOWER TONIGHT AHEAD OF THE LOW LEVEL JET...AND FOR NOW THE LLWS REMARK WAS OMITTED FROM THE TERMINAL FORECASTS. THIS WILL BE REVISITED FOR THE 1200 UTC FORECASTS/ IMPROVED CONDITIONS WILL ARRIVE BEHIND THE DEPARTING SYSTEM ON FRIDAY WITH VFR EXPECTED FRI MORNING. THIS WILL CARRY INTO THE EVENING BEFORE THE NEXT SYSTEM APPROACHES FOR SAT MORNING. MORE WIDESPREAD POOR FLYING WEATHER IS ANTICIPATED FOR SAT AND SAT NIGHT. && .MARINE... A SMALL CRAFT ADVISORY WILL BE RAISED WITH THE NEW FORECAST FOR ALL MARINE ZONES FOR TONIGHT. THE SURFACE GRADIENT AHEAD OF THE HIGH APPROACHING FROM THE WEST HAS KEPT THE WINDS BETWEEN 15 AND 20 KNOTS THROUGH THE EARLY MORNING HOURS. SURFACE STREAMLINES TO THE WEST SUGGEST THIS WILL CHANGE SOON...AS WINDS DROP OFF...AND VEER TO THE NORTHEAST. AS THE HIGH GETS OFFSHORE LATER THIS MORNING...THE FLOW WILL VEER TO THE SOUTH SOUTHWEST. THE GRADIENT LOOKS AS THOUGH IT CAN SUPPORT GUSTS TO NEAR 20 KNOTS LATE THIS AFTERNOON OVER THE SOUTHERN OCEAN WATERS AND ACROSS DELAWARE BAY. HOWEVER...MODEL SOUNDINGS MAY BE A BIT TOO GENEROUS WITH MIXING IN AN INCREASING WARM AIR ADVECTION PATTERN... AND WINDS AND SEAS WILL BE KEPT BELOW SMALL CRAFT LEVELS THROUGH DUSK. AS A COLD FRONT APPROACHES THIS EVENING...THE SURFACE GRADIENT LOOKS TO BE ABLE TO SUPPORT SMALL CRAFT WINDS ACROSS ALL WATERS...PROBABLY STARTING IN THE NEIGHBORHOOD OF 0000 UTC. MODELS HAVE BEEN CONSISTENT SHOWING A LOW LEVEL JET CROSSING THE REGION LATE THIS EVENING AND DURING THE OVERNIGHT. MODEL SOUNDINGS SHOW A 3 HOUR WINDOW (CENTERED AROUND 0600 UTC FRIDAY) WHERE 30 TO 35 KNOTS OF WIND DROP BELOW THE INVERSION. TYPICALLY...IT IS DIFFICULT TO GET A SOUTHWEST FLOW IN STRONG WARM AIR ADVECTION TO WORK ITS WAY BELOW A LOWERING INVERSION...AND THIS LOOKS LIKE A TYPICAL WARM AIR ADVECTION PATTERN. WHILE THE SIGNATURE IS PRESENT IN BOTH THE NAM AND GFS AT 44009...WILL HOLD OFF ON ISSUING A GALE WARNING. HOWEVER...30 KNOT GUSTS WILL BE INCLUDED IN THE FORECAST FOR THE SOUTHERN OCEAN WATERS AND THE LOWER DELAWARE BAY...WHERE THE LOW LEVEL JET WILL MAKE ITS CLOSEST PASS. IF ANY PLACES END UP NEEDING A SHORT FUSED GALE WARNING TONIGHT...IT WOULD BE THE ABOVEMENTIONED LOCATIONS. THE COLD FRONT IS EXPECTED TO CROSS THE COASTAL WATERS BETWEEN 0800 AND 1200 UTC FRIDAY. THE COLD AIR ADVECTION BEHIND THE COLD FRONT DOES NOT APPEAR TO BE SUFFICIENT TO KEEP WINDS AT SMALL CRAFT LEVELS. THEREFORE...THE SMALL CRAFT ADVISORY WILL COVER JUST THE TONIGHT PERIOD. MORE SMALL CRAFT ADVISORY CONDITIONS WILL DEVELOP ON THE WATERS WITH THE SYSTEM THAT WILL AFFECT THE WATERS SATURDAY NIGHT AND SUNDAY. THE ENHANCED SEAS MAY PERSIST INTO MONDAY. && .PHI WATCHES/WARNINGS/ADVISORIES... PA...NONE. NJ...NONE. DE...NONE. MD...NONE. MARINE...SMALL CRAFT ADVISORY FROM 7 PM THIS EVENING TO 6 AM EST FRIDAY FOR ANZ430-431-450>455. && $$ SYNOPSIS...O`HARA NEAR TERM...GIGI/HAYES SHORT TERM...HAYES LONG TERM...O`HARA AVIATION...HAYES/O`HARA MARINE...HAYES/O`HARA
AREA FORECAST DISCUSSION
NWS MIAMI FL
1221 PM EST THU JAN 19 2012 .AVIATION...VFR CONDITIONS EXPECTED NEXT 24 HRS. SURFACE WINDS FROM NE AROUND 10 KNOTS SHOULD DECREASE TO AROUND 4-5 KNOTS OVERNIGHT. SFC HIGH PRESSURE MOVING TO WESTERN ATLANTIC SHOULD RESULT IN SFC WINDS BECOMING MORE EAST AND INCREASING TO AROUND 10 KTS BY MID MORNING FRIDAY. && .PREV DISCUSSION... /ISSUED 924 AM EST THU JAN 19 2012/ UPDATE... A WEAK BOUNDARY WAS MOVING THROUGH SOUTH FLORIDA THIS MORNING. THE ONLY NOTABLE FEATURE IS THE CLOUD COVER ACROSS DEEP SOUTH FLORIDA. THIS BOUNDARY WILL BECOME EVEN MORE DIFFUSE LATER TODAY...BUT DRIER AIR WILL CONTINUE TO FILTER INTO THE REGION. SLIGHTLY COOLER TEMPERATURES ARE EXPECTED THIS AFTERNOON. NO MAJOR UPDATES NEEDED THIS MORNING. PREV DISCUSSION... /ISSUED 546 AM EST THU JAN 19 2012/ AVIATION...WEAKENING COLD FRNT APRCHG LK OKEE AREA AND WL MOV INTO S FLA AND MOV OFF OF THE SE COAST ARND 15Z. MVFR CIGS WITH LCL IFR OCCURRING AHD OF FRNT. MVFR CIGS PSBL E COAST TERMINALS 11Z-14Z THEN VFR ALL TERMINALS THRU THE END OF THE PD. SFC WNDS NNW-N < 10 KTS BCMG NNE ALL TERMINALS AFT 18Z AND INCRG 10 TO 15 KTS THEN DCRG < 10 KTS AFT 00Z. POTENTIAL EXISTS THAT AN OFSHR WND FLOW MAY DVLP LATE TONIGHT BUT NOT IN TAFS ATTM. PREV DISCUSSION... /ISSUED 324 AM EST THU JAN 19 2012/ DISCUSSION... LATEST DEW POINT SURFACE ANALYSIS REVEALS LEADING EDGE OF WEAK FRONTAL BOUNDARY CURRENTLY ACROSS SOUTH CENTRAL FLORIDA BETWEEN ORLANDO AND LAKE OKEECHOBEE. ANALYSIS OF MODEL GUIDANCE TRACKING THIS FEATURE INDICATES THE BOUNDARY WILL BE ACROSS SOUTH FLORIDA BY LATE MORNING AND/OR EARLY AFTERNOON. GLOBAL MODELS IN FACT BRING IT THROUGH THE AREA BUT THE HIRES MODELS INCLUDING NCEP HIRES NMM AND ARW AS WELL AS THE LOCAL WRF AND THE RUC INDICATE THE BOUNDARY WILL SIMPLY DISSIPATE ACROSS THE AREA AS IT MOVES INTO SOUTH FLORIDA TODAY. EITHER WAY DRIER AIR WILL BE MOVING INTO THE AREA WITH IT. AHEAD OF IT, RADAR AND SATELLITE INDICATED SOME CONVECTION EARLIER THIS MORNING MOVING INTO THE GULF WATERS BUT IT HAS DISSIPATED SINCE THEN AS LOW LEVEL FORCING WITH THE FRONT WEAKENS AND AS IT MOVES FARTHER AWAY FROM UPPER LEVEL DYNAMICS WELL REMOVED TO THE NORTH. SO FAR LOOKS LIKE CLOUDS ASSOCIATED WITH THE APPROACHING BOUNDARY ARE PREVENTING PATCHY FOG FROM DEVELOPING THIS MORNING ACROSS INTERIOR AREAS OF SOUTH FLORIDA AND THAT IS LIKELY TO REMAIN LIKE THAT BUT WILL CONTINUE TO MONITOR JUST IN CASE. FOR THE MOMENT GIVEN TRENDS LEFT THAT OUT OF THE FORECAST FOR THIS MORNING. AHEAD OF THE BOUNDARY TODAY THERE WILL BE ONLY A SLIGHT CHANCE OF A SHOWER, BEST OVER THE COASTAL WATERS, WITH DRIER AIR MASS GRADUALLY MOVING IN PARTICULARLY BEGINNING AROUND MID TO LATE MORNING AND INTO THE EARLY AFTERNOON. YET RAIN CHANCES NOT ENOUGH TO MENTION IN THE FORECAST. AS ALLUDED TO ABOVE, THE BOUNDARY IS EXPECTED TO STALL AND DISSIPATE BETWEEN MAINLAND SOUTH FLORIDA AND THE STRAITS THROUGH TONIGHT. TEMPERATURES WILL CONTINUE TO BE WARM WITH HIGHS IN THE 70S TODAY...AND THEN INTO THE UPPER 70S TO THE LOWER 80S BY FRIDAY AND INTO THE WEEKEND. WITH THE DRIER AIR AND EXCELLENT RADIATIONAL COOLING...OVERNIGHT LOWS TONIGHT MAY GET INTO THE MID 40S ACROSS THE NORTHWEST INTERIOR. ALSO WITH LIGHT WINDS AND LOW LEVEL FLOW TURNING FROM THE NORTHEAST, IT IS POSSIBLE THAT PATCHY FOG DEVELOPS INLAND AROUND LAKE OKEECHOBEE TONIGHT AND AGAIN FRIDAY NIGHT. HOWEVER, CHANCES OF THAT ARE BEST FRIDAY NIGHT AS BY THEN RETURN FLOW FROM THE ATLANTIC WOULD HAVE HAD MORE TIME TO MOISTEN UP THE LOW LEVELS A BIT. BUT GIVEN ALL MOS GUIDANCE DEVELOP IT TONIGHT ALSO, I PUT IT IN THE GRIDS. OVERALL TONIGHT WILL BE THE COOLEST NIGHT OF THE COMING WEEK. A CAVEAT HERE IS THAT THE MET GUIDANCE IS SIGNIFICANTLY WARMER THAN THE MAV FOR NORTHEAST PORTIONS OF THE AREA (PALM BEACH COUNTY). NAM IS BANKING ON LOT OF CLOUDS RETURNING QUICKLY WITH LOW LEVEL FLOW SHIFTING FROM THE NE. BUT AT THIS TIME DECIDED TO STICK WITH MAV. FLOW WILL NOT BE THAT STRONG AND A LAND BREEZE COULD PREVENT THIS SCENARIO FROM HAPPENING TOO. EKDMOS ENSEMBLE GUIDANCE ALSO SHOWS A MEAN IN THE MID TO UPPER 50S. SO WITH THAT SAID, TEMPS TONIGHT WILL STILL BE A COUPLE OF DEGREES ABOVE NORMAL ACROSS SOUTH FLORIDA WITH A WARMING TREND IN STORE FOR THE UPCOMING WEEKEND AND INTO THE FIRST PART OF NEXT WEEK WHEN MODELS GENERALLY AGREE ON HIGH PRESSURE ALOFT BUILDING FROM THE SOUTHERN GULF OF MEXICO ACROSS CUBA AND INTO THE BAHAMAS, KEEPING JET STREAM AND STORM TRACKS WELL TO OUR NORTH. GFS IS THE MOST AGGRESSIVE OF THE MODELS BUILDING THE AFOREMENTIONED HIGH ALOFT BUT THE MEAN OF THE ENSEMBLE IS STILL CONSISTENT WITH THE SCENARIO AND SO IS THE ECMWF. BOTTOM LINE, THE ENSUING WARMING TREND WILL RESULT IN OVERNIGHT LOWS RUNNING CLOSE TO 10 DEGREES ABOVE NORMAL BY LATE IN THE WEEKEND AND INTO THE EARLY PART OF NEXT WEEK ALONG WITH DAYTIME HIGHS RUNNING AROUND 5 DEGREES ABOVE NORMAL. IT WILL REMAIN DRY FOR THE MOST PART THROUGH THE WEEKEND WITH A SLIGHT CHANCE OF SHOWERS MAY BE COMING BACK INTO THE PICTURE BY THE EARLY TO MIDDLE PART OF NEXT WEEK AS LOW LEVEL MOISTURE SLOWLY RETURNS FROM THE SOUTH BUT NOT LOOKING TOO PROMISING AT THIS TIME. MARINE... A BRIEF SURGE IN WIND OF UP TO 15 TO 20 KNOTS TODAY OFF THE COAST OF PALM BEACH FROM THE NORTH NORTHEAST WILL RESULT IN A SHORT LIVED SURGE IN SEAS OF UP TO 6 FEET IN THE GULF STREAM. SO WILL PUT UP A SMALL CRAFT SHOULD EXERCISE CAUTION FOR THOSE WATERS TODAY. OTHERWISE WINDS AND SEAS WILL REMAIN BELOW 10 TO 15 KNOTS AND BELOW 4 FEET INTO THE EARLY PART OF NEXT WEEK. FIRE WEATHER... MINIMUM RELATIVE HUMIDITY VALUES TODAY WILL BE BELOW 35 PERCENT IN AREAS NORTH OF ALLIGATOR ALLEY ACROSS NORTHERN COLLIER, HENDRY, AND GLADES COUNTIES TODAY FOR CLOSE TO 4 HOURS. HOWEVER ERC VALUES ACROSS THE AREA REMAIN TOO LOW FOR ANY RED FLAG CONCERNS. AFTER TODAY, LOW LEVEL MOISTURE WILL BE ON THE INCREASE AND SO NO OTHER FIRE CONCERNS AT THIS TIME INTO EARLY NEXT WEEK AT THE VERY LEAST. && .PRELIMINARY POINT TEMPS/POPS... WEST PALM BEACH 55 76 61 77 / - - - - FORT LAUDERDALE 61 77 66 78 / - - - - MIAMI 60 77 65 78 / - - - - NAPLES 52 78 57 78 / - - - - && .MFL WATCHES/WARNINGS/ADVISORIES... FL...NONE. AM...NONE. GM...NONE. && $$ DISCUSSION/MARINE/FIRE...84/AK AVIATION/RADAR...47/RGH
AREA FORECAST DISCUSSION
NWS MIAMI FL
924 AM EST THU JAN 19 2012 .UPDATE... A WEAK BOUNDARY WAS MOVING THROUGH SOUTH FLORIDA THIS MORNING. THE ONLY NOTABLE FEATURE IS THE CLOUD COVER ACROSS DEEP SOUTH FLORIDA. THIS BOUNDARY WILL BECOME EVEN MORE DIFFUSE LATER TODAY...BUT DRIER AIR WILL CONTINUE TO FILTER INTO THE REGION. SLIGHTLY COOLER TEMPERATURES ARE EXPECTED THIS AFTERNOON. NO MAJOR UPDATES NEEDED THIS MORNING. && .PREV DISCUSSION... /ISSUED 546 AM EST THU JAN 19 2012/ AVIATION...WEAKENING COLD FRNT APRCHG LK OKEE AREA AND WL MOV INTO S FLA AND MOV OFF OF THE SE COAST ARND 15Z. MVFR CIGS WITH LCL IFR OCCURRING AHD OF FRNT. MVFR CIGS PSBL E COAST TERMINALS 11Z-14Z THEN VFR ALL TERMINALS THRU THE END OF THE PD. SFC WNDS NNW-N < 10 KTS BCMG NNE ALL TERMINALS AFT 18Z AND INCRG 10 TO 15 KTS THEN DCRG < 10 KTS AFT 00Z. POTENTIAL EXISTS THAT AN OFSHR WND FLOW MAY DVLP LATE TONIGHT BUT NOT IN TAFS ATTM. PREV DISCUSSION... /ISSUED 324 AM EST THU JAN 19 2012/ DISCUSSION... LATEST DEW POINT SURFACE ANALYSIS REVEALS LEADING EDGE OF WEAK FRONTAL BOUNDARY CURRENTLY ACROSS SOUTH CENTRAL FLORIDA BETWEEN ORLANDO AND LAKE OKEECHOBEE. ANALYSIS OF MODEL GUIDANCE TRACKING THIS FEATURE INDICATES THE BOUNDARY WILL BE ACROSS SOUTH FLORIDA BY LATE MORNING AND/OR EARLY AFTERNOON. GLOBAL MODELS IN FACT BRING IT THROUGH THE AREA BUT THE HIRES MODELS INCLUDING NCEP HIRES NMM AND ARW AS WELL AS THE LOCAL WRF AND THE RUC INDICATE THE BOUNDARY WILL SIMPLY DISSIPATE ACROSS THE AREA AS IT MOVES INTO SOUTH FLORIDA TODAY. EITHER WAY DRIER AIR WILL BE MOVING INTO THE AREA WITH IT. AHEAD OF IT, RADAR AND SATELLITE INDICATED SOME CONVECTION EARLIER THIS MORNING MOVING INTO THE GULF WATERS BUT IT HAS DISSIPATED SINCE THEN AS LOW LEVEL FORCING WITH THE FRONT WEAKENS AND AS IT MOVES FARTHER AWAY FROM UPPER LEVEL DYNAMICS WELL REMOVED TO THE NORTH. SO FAR LOOKS LIKE CLOUDS ASSOCIATED WITH THE APPROACHING BOUNDARY ARE PREVENTING PATCHY FOG FROM DEVELOPING THIS MORNING ACROSS INTERIOR AREAS OF SOUTH FLORIDA AND THAT IS LIKELY TO REMAIN LIKE THAT BUT WILL CONTINUE TO MONITOR JUST IN CASE. FOR THE MOMENT GIVEN TRENDS LEFT THAT OUT OF THE FORECAST FOR THIS MORNING. AHEAD OF THE BOUNDARY TODAY THERE WILL BE ONLY A SLIGHT CHANCE OF A SHOWER, BEST OVER THE COASTAL WATERS, WITH DRIER AIR MASS GRADUALLY MOVING IN PARTICULARLY BEGINNING AROUND MID TO LATE MORNING AND INTO THE EARLY AFTERNOON. YET RAIN CHANCES NOT ENOUGH TO MENTION IN THE FORECAST. AS ALLUDED TO ABOVE, THE BOUNDARY IS EXPECTED TO STALL AND DISSIPATE BETWEEN MAINLAND SOUTH FLORIDA AND THE STRAITS THROUGH TONIGHT. TEMPERATURES WILL CONTINUE TO BE WARM WITH HIGHS IN THE 70S TODAY...AND THEN INTO THE UPPER 70S TO THE LOWER 80S BY FRIDAY AND INTO THE WEEKEND. WITH THE DRIER AIR AND EXCELLENT RADIATIONAL COOLING...OVERNIGHT LOWS TONIGHT MAY GET INTO THE MID 40S ACROSS THE NORTHWEST INTERIOR. ALSO WITH LIGHT WINDS AND LOW LEVEL FLOW TURNING FROM THE NORTHEAST, IT IS POSSIBLE THAT PATCHY FOG DEVELOPS INLAND AROUND LAKE OKEECHOBEE TONIGHT AND AGAIN FRIDAY NIGHT. HOWEVER, CHANCES OF THAT ARE BEST FRIDAY NIGHT AS BY THEN RETURN FLOW FROM THE ATLANTIC WOULD HAVE HAD MORE TIME TO MOISTEN UP THE LOW LEVELS A BIT. BUT GIVEN ALL MOS GUIDANCE DEVELOP IT TONIGHT ALSO, I PUT IT IN THE GRIDS. OVERALL TONIGHT WILL BE THE COOLEST NIGHT OF THE COMING WEEK. A CAVEAT HERE IS THAT THE MET GUIDANCE IS SIGNIFICANTLY WARMER THAN THE MAV FOR NORTHEAST PORTIONS OF THE AREA (PALM BEACH COUNTY). NAM IS BANKING ON LOT OF CLOUDS RETURNING QUICKLY WITH LOW LEVEL FLOW SHIFTING FROM THE NE. BUT AT THIS TIME DECIDED TO STICK WITH MAV. FLOW WILL NOT BE THAT STRONG AND A LAND BREEZE COULD PREVENT THIS SCENARIO FROM HAPPENING TOO. EKDMOS ENSEMBLE GUIDANCE ALSO SHOWS A MEAN IN THE MID TO UPPER 50S. SO WITH THAT SAID, TEMPS TONIGHT WILL STILL BE A COUPLE OF DEGREES ABOVE NORMAL ACROSS SOUTH FLORIDA WITH A WARMING TREND IN STORE FOR THE UPCOMING WEEKEND AND INTO THE FIRST PART OF NEXT WEEK WHEN MODELS GENERALLY AGREE ON HIGH PRESSURE ALOFT BUILDING FROM THE SOUTHERN GULF OF MEXICO ACROSS CUBA AND INTO THE BAHAMAS, KEEPING JET STREAM AND STORM TRACKS WELL TO OUR NORTH. GFS IS THE MOST AGGRESSIVE OF THE MODELS BUILDING THE AFOREMENTIONED HIGH ALOFT BUT THE MEAN OF THE ENSEMBLE IS STILL CONSISTENT WITH THE SCENARIO AND SO IS THE ECMWF. BOTTOM LINE, THE ENSUING WARMING TREND WILL RESULT IN OVERNIGHT LOWS RUNNING CLOSE TO 10 DEGREES ABOVE NORMAL BY LATE IN THE WEEKEND AND INTO THE EARLY PART OF NEXT WEEK ALONG WITH DAYTIME HIGHS RUNNING AROUND 5 DEGREES ABOVE NORMAL. IT WILL REMAIN DRY FOR THE MOST PART THROUGH THE WEEKEND WITH A SLIGHT CHANCE OF SHOWERS MAY BE COMING BACK INTO THE PICTURE BY THE EARLY TO MIDDLE PART OF NEXT WEEK AS LOW LEVEL MOISTURE SLOWLY RETURNS FROM THE SOUTH BUT NOT LOOKING TOO PROMISING AT THIS TIME. MARINE... A BRIEF SURGE IN WIND OF UP TO 15 TO 20 KNOTS TODAY OFF THE COAST OF PALM BEACH FROM THE NORTH NORTHEAST WILL RESULT IN A SHORT LIVED SURGE IN SEAS OF UP TO 6 FEET IN THE GULF STREAM. SO WILL PUT UP A SMALL CRAFT SHOULD EXERCISE CAUTION FOR THOSE WATERS TODAY. OTHERWISE WINDS AND SEAS WILL REMAIN BELOW 10 TO 15 KNOTS AND BELOW 4 FEET INTO THE EARLY PART OF NEXT WEEK. FIRE WEATHER... MINIMUM RELATIVE HUMIDITY VALUES TODAY WILL BE BELOW 35 PERCENT IN AREAS NORTH OF ALLIGATOR ALLEY ACROSS NORTHERN COLLIER, HENDRY, AND GLADES COUNTIES TODAY FOR CLOSE TO 4 HOURS. HOWEVER ERC VALUES ACROSS THE AREA REMAIN TOO LOW FOR ANY RED FLAG CONCERNS. AFTER TODAY, LOW LEVEL MOISTURE WILL BE ON THE INCREASE AND SO NO OTHER FIRE CONCERNS AT THIS TIME INTO EARLY NEXT WEEK AT THE VERY LEAST. && .PRELIMINARY POINT TEMPS/POPS... WEST PALM BEACH 74 55 76 61 / - - - - FORT LAUDERDALE 75 61 77 66 / - - - - MIAMI 76 60 77 65 / - - - - NAPLES 73 52 78 57 / - - - - && .MFL WATCHES/WARNINGS/ADVISORIES... FL...NONE. AM...NONE. GM...NONE. && $$ DISCUSSION/MARINE/FIRE...84/AK AVIATION/RADAR...47/RGH
AREA FORECAST DISCUSSION
NWS MIAMI FL
546 AM EST THU JAN 19 2012 .AVIATION...WEAKENING COLD FRNT APRCHG LK OKEE AREA AND WL MOV INTO S FLA AND MOV OFF OF THE SE COAST ARND 15Z. MVFR CIGS WITH LCL IFR OCCURRING AHD OF FRNT. MVFR CIGS PSBL E COAST TERMINALS 11Z-14Z THEN VFR ALL TERMINALS THRU THE END OF THE PD. SFC WNDS NNW-N < 10 KTS BCMG NNE ALL TERMINALS AFT 18Z AND INCRG 10 TO 15 KTS THEN DCRG < 10 KTS AFT 00Z. POTENTIAL EXISTS THAT AN OFSHR WND FLOW MAY DVLP LATE TONIGHT BUT NOT IN TAFS ATTM. && .PREV DISCUSSION... /ISSUED 324 AM EST THU JAN 19 2012/ DISCUSSION... LATEST DEW POINT SURFACE ANALYSIS REVEALS LEADING EDGE OF WEAK FRONTAL BOUNDARY CURRENTLY ACROSS SOUTH CENTRAL FLORIDA BETWEEN ORLANDO AND LAKE OKEECHOBEE. ANALYSIS OF MODEL GUIDANCE TRACKING THIS FEATURE INDICATES THE BOUNDARY WILL BE ACROSS SOUTH FLORIDA BY LATE MORNING AND/OR EARLY AFTERNOON. GLOBAL MODELS IN FACT BRING IT THROUGH THE AREA BUT THE HIRES MODELS INCLUDING NCEP HIRES NMM AND ARW AS WELL AS THE LOCAL WRF AND THE RUC INDICATE THE BOUNDARY WILL SIMPLY DISSIPATE ACROSS THE AREA AS IT MOVES INTO SOUTH FLORIDA TODAY. EITHER WAY DRIER AIR WILL BE MOVING INTO THE AREA WITH IT. AHEAD OF IT, RADAR AND SATELLITE INDICATED SOME CONVECTION EARLIER THIS MORNING MOVING INTO THE GULF WATERS BUT IT HAS DISSIPATED SINCE THEN AS LOW LEVEL FORCING WITH THE FRONT WEAKENS AND AS IT MOVES FARTHER AWAY FROM UPPER LEVEL DYNAMICS WELL REMOVED TO THE NORTH. SO FAR LOOKS LIKE CLOUDS ASSOCIATED WITH THE APPROACHING BOUNDARY ARE PREVENTING PATCHY FOG FROM DEVELOPING THIS MORNING ACROSS INTERIOR AREAS OF SOUTH FLORIDA AND THAT IS LIKELY TO REMAIN LIKE THAT BUT WILL CONTINUE TO MONITOR JUST IN CASE. FOR THE MOMENT GIVEN TRENDS LEFT THAT OUT OF THE FORECAST FOR THIS MORNING. AHEAD OF THE BOUNDARY TODAY THERE WILL BE ONLY A SLIGHT CHANCE OF A SHOWER, BEST OVER THE COASTAL WATERS, WITH DRIER AIR MASS GRADUALLY MOVING IN PARTICULARLY BEGINNING AROUND MID TO LATE MORNING AND INTO THE EARLY AFTERNOON. YET RAIN CHANCES NOT ENOUGH TO MENTION IN THE FORECAST. AS ALLUDED TO ABOVE, THE BOUNDARY IS EXPECTED TO STALL AND DISSIPATE BETWEEN MAINLAND SOUTH FLORIDA AND THE STRAITS THROUGH TONIGHT. TEMPERATURES WILL CONTINUE TO BE WARM WITH HIGHS IN THE 70S TODAY...AND THEN INTO THE UPPER 70S TO THE LOWER 80S BY FRIDAY AND INTO THE WEEKEND. WITH THE DRIER AIR AND EXCELLENT RADIATIONAL COOLING...OVERNIGHT LOWS TONIGHT MAY GET INTO THE MID 40S ACROSS THE NORTHWEST INTERIOR. ALSO WITH LIGHT WINDS AND LOW LEVEL FLOW TURNING FROM THE NORTHEAST, IT IS POSSIBLE THAT PATCHY FOG DEVELOPS INLAND AROUND LAKE OKEECHOBEE TONIGHT AND AGAIN FRIDAY NIGHT. HOWEVER, CHANCES OF THAT ARE BEST FRIDAY NIGHT AS BY THEN RETURN FLOW FROM THE ATLANTIC WOULD HAVE HAD MORE TIME TO MOISTEN UP THE LOW LEVELS A BIT. BUT GIVEN ALL MOS GUIDANCE DEVELOP IT TONIGHT ALSO, I PUT IT IN THE GRIDS. OVERALL TONIGHT WILL BE THE COOLEST NIGHT OF THE COMING WEEK. A CAVEAT HERE IS THAT THE MET GUIDANCE IS SIGNIFICANTLY WARMER THAN THE MAV FOR NORTHEAST PORTIONS OF THE AREA (PALM BEACH COUNTY). NAM IS BANKING ON LOT OF CLOUDS RETURNING QUICKLY WITH LOW LEVEL FLOW SHIFTING FROM THE NE. BUT AT THIS TIME DECIDED TO STICK WITH MAV. FLOW WILL NOT BE THAT STRONG AND A LAND BREEZE COULD PREVENT THIS SCENARIO FROM HAPPENING TOO. EKDMOS ENSEMBLE GUIDANCE ALSO SHOWS A MEAN IN THE MID TO UPPER 50S. SO WITH THAT SAID, TEMPS TONIGHT WILL STILL BE A COUPLE OF DEGREES ABOVE NORMAL ACROSS SOUTH FLORIDA WITH A WARMING TREND IN STORE FOR THE UPCOMING WEEKEND AND INTO THE FIRST PART OF NEXT WEEK WHEN MODELS GENERALLY AGREE ON HIGH PRESSURE ALOFT BUILDING FROM THE SOUTHERN GULF OF MEXICO ACROSS CUBA AND INTO THE BAHAMAS, KEEPING JET STREAM AND STORM TRACKS WELL TO OUR NORTH. GFS IS THE MOST AGGRESSIVE OF THE MODELS BUILDING THE AFOREMENTIONED HIGH ALOFT BUT THE MEAN OF THE ENSEMBLE IS STILL CONSISTENT WITH THE SCENARIO AND SO IS THE ECMWF. BOTTOM LINE, THE ENSUING WARMING TREND WILL RESULT IN OVERNIGHT LOWS RUNNING CLOSE TO 10 DEGREES ABOVE NORMAL BY LATE IN THE WEEKEND AND INTO THE EARLY PART OF NEXT WEEK ALONG WITH DAYTIME HIGHS RUNNING AROUND 5 DEGREES ABOVE NORMAL. IT WILL REMAIN DRY FOR THE MOST PART THROUGH THE WEEKEND WITH A SLIGHT CHANCE OF SHOWERS MAY BE COMING BACK INTO THE PICTURE BY THE EARLY TO MIDDLE PART OF NEXT WEEK AS LOW LEVEL MOISTURE SLOWLY RETURNS FROM THE SOUTH BUT NOT LOOKING TOO PROMISING AT THIS TIME. MARINE... A BRIEF SURGE IN WIND OF UP TO 15 TO 20 KNOTS TODAY OFF THE COAST OF PALM BEACH FROM THE NORTH NORTHEAST WILL RESULT IN A SHORT LIVED SURGE IN SEAS OF UP TO 6 FEET IN THE GULF STREAM. SO WILL PUT UP A SMALL CRAFT SHOULD EXERCISE CAUTION FOR THOSE WATERS TODAY. OTHERWISE WINDS AND SEAS WILL REMAIN BELOW 10 TO 15 KNOTS AND BELOW 4 FEET INTO THE EARLY PART OF NEXT WEEK. FIRE WEATHER... MINIMUM RELATIVE HUMIDITY VALUES TODAY WILL BE BELOW 35 PERCENT IN AREAS NORTH OF ALLIGATOR ALLEY ACROSS NORTHERN COLLIER, HENDRY, AND GLADES COUNTIES TODAY FOR CLOSE TO 4 HOURS. HOWEVER ERC VALUES ACROSS THE AREA REMAIN TOO LOW FOR ANY RED FLAG CONCERNS. AFTER TODAY, LOW LEVEL MOISTURE WILL BE ON THE INCREASE AND SO NO OTHER FIRE CONCERNS AT THIS TIME INTO EARLY NEXT WEEK AT THE VERY LEAST. && .PRELIMINARY POINT TEMPS/POPS... WEST PALM BEACH 74 55 76 61 / - - - - FORT LAUDERDALE 75 61 77 66 / - - - - MIAMI 76 60 77 65 / - - - - NAPLES 73 52 78 57 / - - - - && .MFL WATCHES/WARNINGS/ADVISORIES... FL...NONE. AM...NONE. GM...NONE. && $$ DISCUSSION/MARINE/FIRE...52/PS AVIATION/RADAR...15/JR
AREA FORECAST DISCUSSION..CORRECTED
NWS MIAMI FL
324 AM EST THU JAN 19 2012 CORRECTION TO THIRD PARAGRAPH. .DISCUSSION... LATEST DEW POINT SURFACE ANALYSIS REVEALS LEADING EDGE OF WEAK FRONTAL BOUNDARY CURRENTLY ACROSS SOUTH CENTRAL FLORIDA BETWEEN ORLANDO AND LAKE OKEECHOBEE. ANALYSIS OF MODEL GUIDANCE TRACKING THIS FEATURE INDICATES THE BOUNDARY WILL BE ACROSS SOUTH FLORIDA BY LATE MORNING AND/OR EARLY AFTERNOON. GLOBAL MODELS IN FACT BRING IT THROUGH THE AREA BUT THE HIRES MODELS INCLUDING NCEP HIRES NMM AND ARW AS WELL AS THE LOCAL WRF AND THE RUC INDICATE THE BOUNDARY WILL SIMPLY DISSIPATE ACROSS THE AREA AS IT MOVES INTO SOUTH FLORIDA TODAY. EITHER WAY DRIER AIR WILL BE MOVING INTO THE AREA WITH IT. AHEAD OF IT, RADAR AND SATELLITE INDICATED SOME CONVECTION EARLIER THIS MORNING MOVING INTO THE GULF WATERS BUT IT HAS DISSIPATED SINCE THEN AS LOW LEVEL FORCING WITH THE FRONT WEAKENS AND AS IT MOVES FARTHER AWAY FROM UPPER LEVEL DYNAMICS WELL REMOVED TO THE NORTH. SO FAR LOOKS LIKE CLOUDS ASSOCIATED WITH THE APPROACHING BOUNDARY ARE PREVENTING PATCHY FOG FROM DEVELOPING THIS MORNING ACROSS INTERIOR AREAS OF SOUTH FLORIDA AND THAT IS LIKELY TO REMAIN LIKE THAT BUT WILL CONTINUE TO MONITOR JUST IN CASE. FOR THE MOMENT GIVEN TRENDS LEFT THAT OUT OF THE FORECAST FOR THIS MORNING. AHEAD OF THE BOUNDARY TODAY THERE WILL BE ONLY A SLIGHT CHANCE OF A SHOWER, BEST OVER THE COASTAL WATERS, WITH DRIER AIR MASS GRADUALLY MOVING IN PARTICULARLY BEGINNING AROUND MID TO LATE MORNING AND INTO THE EARLY AFTERNOON. YET RAIN CHANCES NOT ENOUGH TO MENTION IN THE FORECAST. AS ALLUDED TO ABOVE, THE BOUNDARY IS EXPECTED TO STALL AND DISSIPATE BETWEEN MAINLAND SOUTH FLORIDA AND THE STRAITS THROUGH TONIGHT. TEMPERATURES WILL CONTINUE TO BE WARM WITH HIGHS IN THE 70S TODAY...AND THEN INTO THE UPPER 70S TO THE LOWER 80S BY FRIDAY AND INTO THE WEEKEND. WITH THE DRIER AIR AND EXCELLENT RADIATIONAL COOLING...OVERNIGHT LOWS TONIGHT MAY GET INTO THE MID 40S ACROSS THE NORTHWEST INTERIOR. ALSO WITH LIGHT WINDS AND LOW LEVEL FLOW TURNING FROM THE NORTHEAST, IT IS POSSIBLE THAT PATCHY FOG DEVELOPS INLAND AROUND LAKE OKEECHOBEE TONIGHT AND AGAIN FRIDAY NIGHT. HOWEVER, CHANCES OF THAT ARE BEST FRIDAY NIGHT AS BY THEN RETURN FLOW FROM THE ATLANTIC WOULD HAVE HAD MORE TIME TO MOISTEN UP THE LOW LEVELS A BIT. BUT GIVEN ALL MOS GUIDANCE DEVELOP IT TONIGHT ALSO, I PUT IT IN THE GRIDS. OVERALL TONIGHT WILL BE THE COOLEST NIGHT OF THE COMING WEEK. A CAVEAT HERE IS THAT THE MET GUIDANCE IS SIGNIFICANTLY WARMER THAN THE MAV FOR NORTHEAST PORTIONS OF THE AREA (PALM BEACH COUNTY). NAM IS BANKING ON LOT OF CLOUDS RETURNING QUICKLY WITH LOW LEVEL FLOW SHIFTING FROM THE NE. BUT AT THIS TIME DECIDED TO STICK WITH MAV. FLOW WILL NOT BE THAT STRONG AND A LAND BREEZE COULD PREVENT THIS SCENARIO FROM HAPPENING TOO. EKDMOS ENSEMBLE GUIDANCE ALSO SHOWS A MEAN IN THE MID TO UPPER 50S. SO WITH THAT SAID, TEMPS TONIGHT WILL STILL BE A COUPLE OF DEGREES ABOVE NORMAL ACROSS SOUTH FLORIDA WITH A WARMING TREND IN STORE FOR THE UPCOMING WEEKEND AND INTO THE FIRST PART OF NEXT WEEK WHEN MODELS GENERALLY AGREE ON HIGH PRESSURE ALOFT BUILDING FROM THE SOUTHERN GULF OF MEXICO ACROSS CUBA AND INTO THE BAHAMAS, KEEPING JET STREAM AND STORM TRACKS WELL TO OUR NORTH. GFS IS THE MOST AGGRESSIVE OF THE MODELS BUILDING THE AFOREMENTIONED HIGH ALOFT BUT THE MEAN OF THE ENSEMBLE IS STILL CONSISTENT WITH THE SCENARIO AND SO IS THE ECMWF. BOTTOM LINE, THE ENSUING WARMING TREND WILL RESULT IN OVERNIGHT LOWS RUNNING CLOSE TO 10 DEGREES ABOVE NORMAL BY LATE IN THE WEEKEND AND INTO THE EARLY PART OF NEXT WEEK ALONG WITH DAYTIME HIGHS RUNNING AROUND 5 DEGREES ABOVE NORMAL. IT WILL REMAIN DRY FOR THE MOST PART THROUGH THE WEEKEND WITH A SLIGHT CHANCE OF SHOWERS MAY BE COMING BACK INTO THE PICTURE BY THE EARLY TO MIDDLE PART OF NEXT WEEK AS LOW LEVEL MOISTURE SLOWLY RETURNS FROM THE SOUTH BUT NOT LOOKING TOO PROMISING AT THIS TIME. && .MARINE... A BRIEF SURGE IN WIND OF UP TO 15 TO 20 KNOTS TODAY OFF THE COAST OF PALM BEACH FROM THE NORTH NORTHEAST WILL RESULT IN A SHORT LIVED SURGE IN SEAS OF UP TO 6 FEET IN THE GULF STREAM. SO WILL PUT UP A SMALL CRAFT SHOULD EXERCISE CAUTION FOR THOSE WATERS TODAY. OTHERWISE WINDS AND SEAS WILL REMAIN BELOW 10 TO 15 KNOTS AND BELOW 4 FEET INTO THE EARLY PART OF NEXT WEEK. && .FIRE WEATHER... MINIMUM RELATIVE HUMIDITY VALUES TODAY WILL BE BELOW 35 PERCENT IN AREAS NORTH OF ALLIGATOR ALLEY ACROSS NORTHERN COLLIER, HENDRY, AND GLADES COUNTIES TODAY FOR CLOSE TO 4 HOURS. HOWEVER ERC VALUES ACROSS THE AREA REMAIN TOO LOW FOR ANY RED FLAG CONCERNS. AFTER TODAY, LOW LEVEL MOISTURE WILL BE ON THE INCREASE AND SO NO OTHER FIRE CONCERNS AT THIS TIME INTO EARLY NEXT WEEK AT THE VERY LEAST. && .PRELIMINARY POINT TEMPS/POPS... WEST PALM BEACH 74 55 76 61 / - - - - FORT LAUDERDALE 75 61 77 66 / - - - - MIAMI 76 60 77 65 / - - - - NAPLES 73 52 78 57 / - - - - && .MFL WATCHES/WARNINGS/ADVISORIES... FL...NONE. AM...NONE. GM...NONE. && $$ DISCUSSION/MARINE/FIRE...52/PS AVIATION/RADAR...15/JR
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
938 PM CST FRI JAN 20 2012 .DISCUSSION... 910 PM CST ALL ILLINOIS COUNTIES ARE CLEARED FROM ANY WINTER HEADLINES...WITH INDIANA TO BE FOLLOWING SUIT SHORTLY. STILL SOME LIGHT SNOW SHOWERS TO FLURRIES PERSIST FROM ROUGHLY THE I-57 CORRIDOR AND EAST... BUT OVERALL TRENDS CONTINUE TO DECREASE...AND QUICKLY. FOCUS ON THE OVERNIGHT WILL THEN TURN TO THE POTENTIAL FOR LAKE EFFECT SNOWS WITH A CONVERGENT BOUNDARY THAT IS NOTED ON TMKE FROM EAST OF MILWAUKEE...SOUTHWEST TO ROUGHLY KRAC. HIGH RESOLUTION GUIDANCE HAS BEEN CONSISTENT IN TAKING THE BOUNDARY AND SWINGING IT SOUTH...IMPACTING THE COASTAL CITIES. 850 TO LAKE SURFACE DELTA T/S LOOK SUPPORTIVE FOR A SHORT TIME...AND ALL GUIDANCE KEEPS THE PRESENT CONVERGENT BOUNDARY AND SUBSEQUENT LES PRESENT INTO THE AFTERNOON. NO REAL CHANGE TO THE THINKING FROM DAY SHIFT AND WILL ONLY MAINTAIN THE SLIGHT CHANCE POPS FOR COASTAL LOCATIONS. NOT EXPECTING MUCH ADDITIONAL SNOWFALL WITH THESE SHOWERS...AND AMOUNTS LESS THAN AN INCH. SHEA //PREV DISCUSSION... 655 PM CST THE HEAVIEST OF SNOWFALL IS BEGINNING TO SHIFT EAST OF THE AREA WITH MOST LOCATIONS AT OR ABOVE 1/2 TO 1 MILE VIS. THE EARLIER HEAVY BANDING LINED UP NICELY WITH AN AREA OF RUC ANALYZED FGEN WITHIN THE H85 TO H7 LAYER. THAT AREA WILL CONTINUE TO WEAKEN AND SHIFT EAST - AND NOT EXPECTING ANY FURTHER SIGNIFICANT REDUCTIONS TO VIS OR INCH PER HOUR SNOWFALL THOUGH THE EVENING. THE BACK EDGE OF THE PRECIP IS NOTED BASICALLY NOTED FROM WHITEWATER WISCONSIN...SOUTHWEST THROUGH FREEPORT ILLINOIS. PRESENT WSW GOES THROUGH 03Z FOR THE NORTHWESTERN TIER OF COUNTIES...AND MAY BEGIN TO PULL COUNTIES EARLIER AS THE BACK EDGE MOVES THROUGH. FOR COUNTIES EAST...STILL EXPECT THE SNOWFALL TO DECREASE THROUGH THE EVENING WITH ONLY MINOR ACCUMULATIONS FOR AREAS WEST OTHE 355/57 CORRIDOR...AND ANOTHER INCH OR SO FOR LOCATIONS ALONG THE ILLINOIS/INDIANA BORDER AND EAST. SHEA .PREVIOUS DISCUSSION... 344 PM CST NO MAJOR SURPRISES SO FAR...DID EXPAND THE WINTER STORM WARNING INTO LEE COUNTY THIS AFTERNOON WHICH HAS SEEN PROLONGED PERIOD OF HEAVIER SNOWFALL WITH DECENT RETURNS STILL UPSTREAM. KENDALL AND WILL COUNTIES WILL BE CLOSE TO WARNING CRITERIA OF 6" AS AXIS OF MAXIMUM SNOW SETS UP PRETTY MUCH AS EXPECTED BETWEEN THE I-90 AND I-80 CORRIDORS WITH RATES OF AN INCH AN HOUR...OCCASIONALLY 1.5 INCHES PER HOUR. EXPECT INTENSITIES TO PEAK ACROSS THE CHICAGO METRO AREA THROUGH THE EARLY EVENING. DID GET OFF TO A SLOWER START THAN EXPECTED AND SNOW:LIQUID RATIOS HAVE BEEN A BIT LOWER THAN ORIGINALLY ANTICIPATED...SO FOR NOW BELIEVE DESPITE THE AXIS SETTING UP FARTHER SOUTH THAN THE ORIGINAL WARNING AREA...THAT ADVISORY FOR 4 TO 6 INCHES ACROSS KENDALL/WILL COUNTIES AND LAKE COUNTY INDIANA WILL STAND //THOUGH MAY SEE SOME LOCALIZED AREAS AT OR JUST ABOVE 6 INCHES PARTICULARLY ACROSS FAR NORTHERN WILL COUNTY//. WIDESPREAD VSBY OF 1/4 MILE OR LESS HAS BEEN REPORTED AND INTERMITTENT PERIODS OF HEAVY SNOW CONTINUE SO ROADWAYS WILL BE A MESS THROUGH THE EVENING HOURS. SATURDAY THROUGH FRIDAY... SHORT TERM...SATURDAY THROUGH MONDAY...FOLLOWING THE PASSAGE OF THE MID LEVEL SYSTEM RESPONSIBLE FOR THE SYNOPTIC SNOW...THE INITIAL FORECAST CONCERN WILL FOCUS ON THE POTENTIAL FOR A LAKE EFFECT BAND OF SNOW MOVING INTO NERN IL. ALL OF THE GUIDANCE IS INDICATING LAKE SFC-850MB DELTA-T AROUND 15C OVER SOUTHERN LAKE MICHIGAN...WHICH WOULD BE CONDUCIVE TO LAKE EFFECT SNOW DEVELOPMENT. THE HIGH RES WRF-ARW/NMM WITH SUPPORT OF THE OPERATIONAL NAM12...ALL INDICATE A CONVERGENCE BAND FORMING OVER SOUTHERN LAKE MICHIGAN...WITH THE POSSIBILITY OF MESOVORTEX DEVELOPMENT WITHIN THE CONVERGENCE ZONE AND INVERTED TROUGH. WITH TIME...THE BAND SHOULD GRADUALLY MOVE INLAND AND TO THE NORTHWEST...POSSIBLE AFFECTING PORTIONS OF NERN AND NCNTRL IL. CONCURRENTLY...LAKE SFC-850MB DELTA T VALUES WILL BE ON THE DECREASE. SO...EXPECT MORE OF AN ADVECTING BAND OF LAKE EFFECT SNOW THAN CONTINUOUS PRODUCTION OF LAKE EFFECT SNOW OVER THE IMMEDIATE LAKE FRONT LOCATIONS. AT THIS TIME...HAVE OPTED TO DEPICT THIS LAKE EFFECT BAND IN THE GRIDDED FORECAST GRAPHICS WITH AN AREA OF CHANCE TO SLIGHT CHANCE POPS WITH -SHSN. THERE IS CERTAINLY THE POTENTIAL FOR ADDITIONAL ACCUMULATING SNOW WITH THE MAIN CONVERGENCE AREA...BUT DUE TO THE MESOSCALE NATURE OF ANY POSSIBLE MESOVORTEX DEVELOPMENT...IT IS NOT POSSIBLE TO PINPOINT ANY POSSIBLE HEAVIER LAKE EFFECT SNOW WITH THIS FEATURE...WHICH WOULD NEED TO BE HANDLED WITH A NEAR TERM FORECAST UPDATE TOMORROW. ON A LARGER SCALE...HIGH PRESSURE SHOULD BUILD OVER THE AREA BRINGING DECREASING CLOUD COVER. TO START OUT SATURDAY MORNING...TEMPERATURES SHOULD RANGE FROM THE LOWER SINGLE DIGITS OVER THE NWRN PORTIONS OF THE CWA...WHERE SKIES SHOULD CLEAR THE EARLIEST AND THE GREATEST AMOUNT OF RADIATING SHOULD OCCUR...TO THE UPPER TEENS ALONG THE LAKE FRONT...WHERE THERE SHOULD BE THE GREATEST AMOUNT OF RESIDUAL CLOUD COVER. WITH AT LEAST PARTIAL SUNSHINE AND AN END TO SUSTAINED COLD ADVECTION OVER THE AREA ON SATURDAY...TEMPERATURES SHOULD SHOULD REBOUND INTO THE LOWER TO MIDDLE 20S. BY SUNDAY...THE HIGH WILL MOVE OFF TO THE EAST. A MORE COMPLICATED SITUATION WILL BE SETTING UP TO THE WEST OF THE LOCAL AREA BY SUNDAY. STRONG NORTHERN AND SOUTHERN STREAM SHORTWAVES ARE EXPECTED TO EJECT OUT OF THE ROCKIES BY SUNDAY MORNING...WITH A LARGE AREA OF LOW PRESSURE DEVELOPING OVER THE CENTRAL PLAINS. THIS WILL INITIATE STRONG WARM/MOIST ADVECTION INTO THE MIDWEST. THE MODELS ARE INDICATING PHASING OF THE NORTHERN AND SOUTHERN STREAMS...WITH A CONSOLIDATED SFC LOW FORMING OVER LOWER MICHIGAN BY MONDAY MORNING. THE MAIN CHANGE TO THE GOING FORECAST WITH RESPECT TO THIS SYSTEM IS TO SPEED UP THE PROGRESSION WITH A COLD FRONTAL PASSAGE LATE SUNDAY NIGHT OR EARLY MONDAY MORNING. WITH THE STRONG WARM ADVECTION...ASSOCIATED PCPN WILL START OUT IN LIQUID FORM AS TEMPERATURES CLIMB INTO THE UPPER 30S TO LOWER 40S THROUGH THE DAY...WITH TEMPERATURES REMAINING NEARLY STEADY INTO THE NIGHT. TEMPERATURES WILL NOT DROP OFF UNTIL AFTER THE FROPA...WHEN TEMPERATURES WILL DROP INTO THE LOWER 20S OVER THE ROCKFORD AREA. FARTHER SOUTHEAST...SOUTH OF THE KANKAKEE VALLEY...TEMPS WILL ONLY DROP INTO THE MIDDLE 30S SO A CHANGEOVER FROM RAIN TO SNOW MAY NOT OCCUR UNTIL LATE IN THE DAY. IT IS EVEN POSSIBLE THAT TEMPS OVER BENTON/JASPER/NEWTON COUNTY AREA MAY NOT COOL OFF ENOUGH BEFORE THE SYSTEM LIFTS OUT LATE MONDAY TO EVER SEE ANY ADDITIONAL SNOW. EXTENDED FORECAST...TUESDAY THROUGH FRIDAY...CONDITIONS SHOULD QUIET DOWN CONSIDERABLY THROUGH THE EXTENDED FORECAST PERIOD. BY TUESDAY...HIGH PRESSURE WILL ONCE AGAIN DOMINATE THE REGION. A SPLIT FLOW PATTERN IS EXPECTED TO DEVELOP WITH AN ACTIVE NORTHERN STREAM FOCUSED ALONG THE CANADIAN BORDER WHILE AN ACTIVE SOUTH STREAM WILL BE FOCUSED ALONG THE RED RIVER VALLEY AND OHIO VALLEY. IN BETWEEN THESE TWO STREAMS...THE MIDDLE MISSISSIPPI VALLEY AND MIDWEST WILL REMAIN UNDER A WEAK RIDGE OF HIGH PRESSURE. THE BEST CHANCE FOR ANY PCPN BETWEEN EARLY TUESDAY AND EARLY FRIDAY WILL BE ON WEDNESDAY WHEN THE NRN STREAM SYSTEM WILL BE PASSING THROUGH THE UPPER GREAT LAKES AND STRONG WARM ADVECTION DEVELOPS OVER THE LOWER AND MIDDLE MISSISSIPPI VALLEY AND SPREADING INTO SOUTHERN IL/IN. BETWEEN THESE TWO SYSTEM...THERE IS A CHANCE FOR SOME LIGHT RAIN OVER THE SOUTHERN PORTIONS OF THE CWA...WITH SOME LIGHT SNOW POSSIBLE OVER THE NRN LOCATIONS. THERE MAY BE A BRIEF TRANSITION OVER TO ALL LIGHT SNOW WEDNESDAY NIGHT...BEFORE THE NRN STREAM SYSTEM SCOOTS OFF TO THE EAST. THE NEXT SIGNIFICANT CHANCE FOR PCPN WILL NOT BE UNTIL LATE IN THE EXTENDED PERIOD...AND WILL BE ASSOCIATED WITH THE SRN STREAM SYSTEM. THE GFS AND ECMWF ARE IN DECENT ENOUGH AGREEMENT ON THIS SYSTEM...THOUGH THE ECMWF IS A BIT FASTER AND HAS A GREATER DEGREE OF PHASING WITH THE NRN STREAM THAN THE GFS...WHICH INDICATES MORE OF A CUT OFF LOW AND...CONSEQUENTLY... IS MORE SLOWLY PROGRESSIVE. DEPENDING ON WHETHER THE FASTER OR THE SLOW SOLUTION VERIFIES...WE COULD SEE PCPN MOVING BACK INTO THE AREA AS EARLY AS THURSDAY PER THE ECMWF OR FRIDAY PER THE GFS. AT THIS POINT...HAVE GONE WITH A MORE MIDDLE OF THE ROAD APPROACH FOR THE LATE EXTENDED PERIOD POPS...WITH SLIGHT CHANCE POPS FOR THURSDAY NIGHT AND CHANCE POPS FOR FRIDAY. KREIN && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 03Z... * SNOW NEARLY OVER AT 03Z...WITH VFR VSBY AND MVFR CIGS CONTINUING. * POTENTIAL FOR LAKE-INDUCED SNOW SHOWERS AT TIMES THROUGH SATURDAY MORNING. RATZER //DISCUSSION...UPDATED 00Z... SNOW BEGINNING TO WIND DOWN FROM THE WEST/NORTHWEST CURRENTLY... WITH RADAR INDICATING HIGHER REFLECTIVITY IN HEAVIER SNOW NOW SOUTH OF KORD. VISIBILITY INCREASING BETTER THAN A MILE GENERALLY NORTHWEST OF A VYS-DPA-ORD LINE AND THIS SHOULD WORK INTO THE CHICAGO AREA TERMINALS IN THE NEXT 2-3 HOURS. KMDW AND KGYY STILL EXPECTED TO SEE SOME 1/2SM TO 1/4SM VIS EARLY...THOUGH MODELS DEPICT RELATIVELY RAPID LOSS OF STRONGER LIFT BEYOND 00-02Z. OUTSIDE OF THE HEAVIER SNOW...CEILINGS GENERALLY MVFR...SO SHOULD SEE FAIRLY RAPID IMPROVEMENT FROM LIFR/IFR CONDITIONS THROUGH EARLY THIS EVENING. OTHER CONCERN IS LAKE-INDUCED SNOW SHOWERS WHICH CURRENTLY CAN BE SEEN ON RADAR IN A LITTLE CONVERGENT BAND OFF KUGN. HIGH RES MODELS INCLUDING RECENT RUC/HRRR RUNS INDICATE THIS CONVERGENT BAND WILL EVENTUALLY SPREAD SOUTHEAST INTO THE PWK/ORD/DPA AREAS DURING THE LATER OVERNIGHT HOURS...AND MAY IMPACT SOME OF THE CHICAGO TAF SITES WITH SOME LIGHT SNOW THROUGH SATURDAY MORNING BEFORE WINDS SHIFT MORE EAST/SOUTHEAST IN THE AFTERNOON. FORECAST SOUNDINGS DEPICT POTENTIAL FOR RELATIVELY SHALLOW LAKE CONVECTION SO NOT EXPECTING SIGNIFICANT ACCUMULATIONS OR VIS REDUCTIONS... BUT WILL HAVE TO MONITOR. AND OF COURSE...EXACT PLACEMENT OF NARROW BAND DIFFICULT AT THIS TIME. WINDS...GENERALLY NORTHEAST THROUGH MIDDAY SATURDAY THOUGH THERE MAY BE A LITTLE VARIABILITY BETWEEN ENE AND NNE THIS EVENING WITH WEAK INVERTED TROUGH ALONG THE WEST SHORE OF LAKE MICHIGAN. SURFACE HIGH BUILDS ACROSS THE AREA BY EARLY SATURDAY AFTERNOON RESULTING IN WINDS EVENTUALLY VEERING BACK TO ESE. RATZER //ORD AND MDW CONFIDENCE...UPDATED 03Z... * HIGH CONFIDENCE IN ENDING OF SNOW SHORTLY...AND MVFR/PATCHY VFR CIGS REMAINDER OF EVENING. * MEDIUM CONFIDENCE IN WIND TRENDS THIS EVENING. * HIGH CONFIDENCE IN CONTINUED LAKE INDUCED SNOW SHOWERS OVER NORTHEAST IL LATER TONIGHT/SATURDAY MORNING...BUT LOW CONFIDENCE ON SPECIFIC TIMING AND PLACEMENT. RATZER //OUTLOOK FOR ORD/MDW FOR 12Z SUNDAY-12Z FRIDAY...UPDATED 00Z... SUNDAY...CHANCE OF RAIN OR DRIZZLE. MVFR PROBABLE WITH IFR CEILINGS/VIS. MONDAY...CHANCE OF RAIN OR SNOW. MVFR POSSIBLE. TUESDAY...VFR. WEDNESDAY...CHANCE OF RAIN OR SNOW...OTHERWISE VFR. THURSDAY...SLGT CHANCE OF LGT SNOW...OTHERWISE VFR. RATZER && .MARINE... 316 PM CST TWO LOW PRESSURE SYSTEMS...ONE OVER ONTARIO AND ONE IN THE OHIO VALLEY...WILL FIGHT FOR INFLUENCE OVER THE LAKE THIS EVENING. THIS WILL RESULT IN VARIABLE WINDS FOR A WHILE...WHICH EVENTUALLY TURN NORTHWEST OVER THE NORTH HALF AND NORTHEAST OVER THE SOUTH AHEAD OF AN APPROACHING CENTER OF HIGH PRESSURE. WINDS GO LIGHT AND VARIABLE AS THE HIGH PRESSURE MOVES ACROSS THE LAKE TOMORROW. BY SUNDAY A NEW LOW PRESSURE SYSTEM AND TRAILING COLD FRONT APPROACH FROM THE WEST. DECISION TO POST A GALE WATCH FOR SUNDAY WAS BASED ON EXPECTATION OF STRONG SOUTH WINDS AHEAD OF THE FRONT...GUSTING INTO THE 35 KT RANGE. ACTUALLY FEEL STRONGER WINDS WILL ARRIVE MONDAY AFTER THE FRONT PASSES AND WINDS TURN WEST. THESE ALSO WILL HAVE THE ADVANTAGE OF BEING COLDER AND IN A MORE WELL MIXED AIRMASS...THUS SUPPORTING BETTER MIXING OF GUSTS TO THE LAKE SURFACE. AT THIS POINT THE REST OF NEXT WEEK LOOKS RELATIVELY QUIET...FOR NOW. LENNING && .LOT WATCHES/WARNINGS/ADVISORIES... IL...WINTER STORM WARNING...ILZ005-ILZ006-ILZ012-ILZ013-ILZ014 UNTIL MIDNIGHT SATURDAY. WINTER WEATHER ADVISORY...ILZ020-ILZ021-ILZ022-ILZ023 UNTIL MIDNIGHT SATURDAY. IN...WINTER WEATHER ADVISORY...INZ001-INZ002-INZ010-INZ011-INZ019 UNTIL MIDNIGHT SATURDAY. LM...GALE WATCH...LMZ080-LMZ261-LMZ362-LMZ364-LMZ366-LMZ563-LMZ565- LMZ567-LMZ669-LMZ671-LMZ673-LMZ675-LMZ777-LMZ779-LMZ868- LMZ870-LMZ872-LMZ874-LMZ876-LMZ878...3 AM SUNDAY TO 9 PM SUNDAY. && $$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
924 PM CST FRI JAN 20 2012 .DISCUSSION... 910 PM CST ALL ILLINOIS COUNTIES ARE CLEARED FROM ANY WINTER HEADLINES...WITH INDIANA TO BE FOLLOWING SUIT SHORTLY. STILL SOME LIGHT SNOW SHOWERS TO FLURRIES PERSIST FROM ROUGHLY THE I-57 CORRIDOR AND EAST... BUT OVERALL TRENDS CONTINUE TO DECREASE...AND QUICKLY. FOCUS ON THE OVERNIGHT WILL THEN TURN TO THE POTENTIAL FOR LAKE EFFECT SNOWS WITH A CONVERGENT BOUNDARY THAT IS NOTED ON TMKE FROM EAST OF MILWAUKEE...SOUTHWEST TO ROUGHLY KRAC. HIGH RESOLUTION GUIDANCE HAS BEEN CONSISTENT IN TAKING THE BOUNDARY AND SWINGING IT SOUTH...IMPACTING THE COASTAL CITIES. 850 TO LAKE SURFACE DELTA T/S LOOK SUPPORTIVE FOR A SHORT TIME...AND ALL GUIDANCE KEEPS THE PRESENT CONVERGENT BOUNDARY AND SUBSEQUENT LES PRESENT INTO THE AFTERNOON. NO REAL CHANGE TO THE THINKING FROM DAY SHIFT AND WILL ONLY MAINTAIN THE SLIGHT CHANCE POPS FOR COASTAL LOCATIONS. NOT EXPECTING MUCH ADDITIONAL SNOWFALL WITH THESE SHOWERS...AND AMOUNTS LESS THAN AN INCH. SHEA && .PREV DISCUSSION... 655 PM CST THE HEAVIEST OF SNOWFALL IS BEGINNING TO SHIFT EAST OF THE AREA WITH MOST LOCATIONS AT OR ABOVE 1/2 TO 1 MILE VIS. THE EARLIER HEAVY BANDING LINED UP NICELY WITH AN AREA OF RUC ANALYZED FGEN WITHIN THE H85 TO H7 LAYER. THAT AREA WILL CONTINUE TO WEAKEN AND SHIFT EAST - AND NOT EXPECTING ANY FURTHER SIGNIFICANT REDUCTIONS TO VIS OR INCH PER HOUR SNOWFALL THOUGH THE EVENING. THE BACK EDGE OF THE PRECIP IS NOTED BASICALLY NOTED FROM WHITEWATER WISCONSIN...SOUTHWEST THROUGH FREEPORT ILLINOIS. PRESENT WSW GOES THROUGH 03Z FOR THE NORTHWESTERN TIER OF COUNTIES...AND MAY BEGIN TO PULL COUNTIES EARLIER AS THE BACK EDGE MOVES THROUGH. FOR COUNTIES EAST...STILL EXPECT THE SNOWFALL TO DECREASE THROUGH THE EVENING WITH ONLY MINOR ACCUMULATIONS FOR AREAS WEST OTHE 355/57 CORRIDOR...AND ANOTHER INCH OR SO FOR LOCATIONS ALONG THE ILLINOIS/INDIANA BORDER AND EAST. SHEA .PREVIOUS DISCUSSION... 344 PM CST NO MAJOR SURPRISES SO FAR...DID EXPAND THE WINTER STORM WARNING INTO LEE COUNTY THIS AFTERNOON WHICH HAS SEEN PROLONGED PERIOD OF HEAVIER SNOWFALL WITH DECENT RETURNS STILL UPSTREAM. KENDALL AND WILL COUNTIES WILL BE CLOSE TO WARNING CRITERIA OF 6" AS AXIS OF MAXIMUM SNOW SETS UP PRETTY MUCH AS EXPECTED BETWEEN THE I-90 AND I-80 CORRIDORS WITH RATES OF AN INCH AN HOUR...OCCASIONALLY 1.5 INCHES PER HOUR. EXPECT INTENSITIES TO PEAK ACROSS THE CHICAGO METRO AREA THROUGH THE EARLY EVENING. DID GET OFF TO A SLOWER START THAN EXPECTED AND SNOW:LIQUID RATIOS HAVE BEEN A BIT LOWER THAN ORIGINALLY ANTICIPATED...SO FOR NOW BELIEVE DESPITE THE AXIS SETTING UP FARTHER SOUTH THAN THE ORIGINAL WARNING AREA...THAT ADVISORY FOR 4 TO 6 INCHES ACROSS KENDALL/WILL COUNTIES AND LAKE COUNTY INDIANA WILL STAND //THOUGH MAY SEE SOME LOCALIZED AREAS AT OR JUST ABOVE 6 INCHES PARTICULARLY ACROSS FAR NORTHERN WILL COUNTY//. WIDESPREAD VSBY OF 1/4 MILE OR LESS HAS BEEN REPORTED AND INTERMITTENT PERIODS OF HEAVY SNOW CONTINUE SO ROADWAYS WILL BE A MESS THROUGH THE EVENING HOURS. SATURDAY THROUGH FRIDAY... SHORT TERM...SATURDAY THROUGH MONDAY...FOLLOWING THE PASSAGE OF THE MID LEVEL SYSTEM RESPONSIBLE FOR THE SYNOPTIC SNOW...THE INITIAL FORECAST CONCERN WILL FOCUS ON THE POTENTIAL FOR A LAKE EFFECT BAND OF SNOW MOVING INTO NERN IL. ALL OF THE GUIDANCE IS INDICATING LAKE SFC-850MB DELTA-T AROUND 15C OVER SOUTHERN LAKE MICHIGAN...WHICH WOULD BE CONDUCIVE TO LAKE EFFECT SNOW DEVELOPMENT. THE HIGH RES WRF-ARW/NMM WITH SUPPORT OF THE OPERATIONAL NAM12...ALL INDICATE A CONVERGENCE BAND FORMING OVER SOUTHERN LAKE MICHIGAN...WITH THE POSSIBILITY OF MESOVORTEX DEVELOPMENT WITHIN THE CONVERGENCE ZONE AND INVERTED TROUGH. WITH TIME...THE BAND SHOULD GRADUALLY MOVE INLAND AND TO THE NORTHWEST...POSSIBLE AFFECTING PORTIONS OF NERN AND NCNTRL IL. CONCURRENTLY...LAKE SFC-850MB DELTA T VALUES WILL BE ON THE DECREASE. SO...EXPECT MORE OF AN ADVECTING BAND OF LAKE EFFECT SNOW THAN CONTINUOUS PRODUCTION OF LAKE EFFECT SNOW OVER THE IMMEDIATE LAKE FRONT LOCATIONS. AT THIS TIME...HAVE OPTED TO DEPICT THIS LAKE EFFECT BAND IN THE GRIDDED FORECAST GRAPHICS WITH AN AREA OF CHANCE TO SLIGHT CHANCE POPS WITH -SHSN. THERE IS CERTAINLY THE POTENTIAL FOR ADDITIONAL ACCUMULATING SNOW WITH THE MAIN CONVERGENCE AREA...BUT DUE TO THE MESOSCALE NATURE OF ANY POSSIBLE MESOVORTEX DEVELOPMENT...IT IS NOT POSSIBLE TO PINPOINT ANY POSSIBLE HEAVIER LAKE EFFECT SNOW WITH THIS FEATURE...WHICH WOULD NEED TO BE HANDLED WITH A NEAR TERM FORECAST UPDATE TOMORROW. ON A LARGER SCALE...HIGH PRESSURE SHOULD BUILD OVER THE AREA BRINGING DECREASING CLOUD COVER. TO START OUT SATURDAY MORNING...TEMPERATURES SHOULD RANGE FROM THE LOWER SINGLE DIGITS OVER THE NWRN PORTIONS OF THE CWA...WHERE SKIES SHOULD CLEAR THE EARLIEST AND THE GREATEST AMOUNT OF RADIATING SHOULD OCCUR...TO THE UPPER TEENS ALONG THE LAKE FRONT...WHERE THERE SHOULD BE THE GREATEST AMOUNT OF RESIDUAL CLOUD COVER. WITH AT LEAST PARTIAL SUNSHINE AND AN END TO SUSTAINED COLD ADVECTION OVER THE AREA ON SATURDAY...TEMPERATURES SHOULD SHOULD REBOUND INTO THE LOWER TO MIDDLE 20S. BY SUNDAY...THE HIGH WILL MOVE OFF TO THE EAST. A MORE COMPLICATED SITUATION WILL BE SETTING UP TO THE WEST OF THE LOCAL AREA BY SUNDAY. STRONG NORTHERN AND SOUTHERN STREAM SHORTWAVES ARE EXPECTED TO EJECT OUT OF THE ROCKIES BY SUNDAY MORNING...WITH A LARGE AREA OF LOW PRESSURE DEVELOPING OVER THE CENTRAL PLAINS. THIS WILL INITIATE STRONG WARM/MOIST ADVECTION INTO THE MIDWEST. THE MODELS ARE INDICATING PHASING OF THE NORTHERN AND SOUTHERN STREAMS...WITH A CONSOLIDATED SFC LOW FORMING OVER LOWER MICHIGAN BY MONDAY MORNING. THE MAIN CHANGE TO THE GOING FORECAST WITH RESPECT TO THIS SYSTEM IS TO SPEED UP THE PROGRESSION WITH A COLD FRONTAL PASSAGE LATE SUNDAY NIGHT OR EARLY MONDAY MORNING. WITH THE STRONG WARM ADVECTION...ASSOCIATED PCPN WILL START OUT IN LIQUID FORM AS TEMPERATURES CLIMB INTO THE UPPER 30S TO LOWER 40S THROUGH THE DAY...WITH TEMPERATURES REMAINING NEARLY STEADY INTO THE NIGHT. TEMPERATURES WILL NOT DROP OFF UNTIL AFTER THE FROPA...WHEN TEMPERATURES WILL DROP INTO THE LOWER 20S OVER THE ROCKFORD AREA. FARTHER SOUTHEAST...SOUTH OF THE KANKAKEE VALLEY...TEMPS WILL ONLY DROP INTO THE MIDDLE 30S SO A CHANGEOVER FROM RAIN TO SNOW MAY NOT OCCUR UNTIL LATE IN THE DAY. IT IS EVEN POSSIBLE THAT TEMPS OVER BENTON/JASPER/NEWTON COUNTY AREA MAY NOT COOL OFF ENOUGH BEFORE THE SYSTEM LIFTS OUT LATE MONDAY TO EVER SEE ANY ADDITIONAL SNOW. EXTENDED FORECAST...TUESDAY THROUGH FRIDAY...CONDITIONS SHOULD QUIET DOWN CONSIDERABLY THROUGH THE EXTENDED FORECAST PERIOD. BY TUESDAY...HIGH PRESSURE WILL ONCE AGAIN DOMINATE THE REGION. A SPLIT FLOW PATTERN IS EXPECTED TO DEVELOP WITH AN ACTIVE NORTHERN STREAM FOCUSED ALONG THE CANADIAN BORDER WHILE AN ACTIVE SOUTH STREAM WILL BE FOCUSED ALONG THE RED RIVER VALLEY AND OHIO VALLEY. IN BETWEEN THESE TWO STREAMS...THE MIDDLE MISSISSIPPI VALLEY AND MIDWEST WILL REMAIN UNDER A WEAK RIDGE OF HIGH PRESSURE. THE BEST CHANCE FOR ANY PCPN BETWEEN EARLY TUESDAY AND EARLY FRIDAY WILL BE ON WEDNESDAY WHEN THE NRN STREAM SYSTEM WILL BE PASSING THROUGH THE UPPER GREAT LAKES AND STRONG WARM ADVECTION DEVELOPS OVER THE LOWER AND MIDDLE MISSISSIPPI VALLEY AND SPREADING INTO SOUTHERN IL/IN. BETWEEN THESE TWO SYSTEM...THERE IS A CHANCE FOR SOME LIGHT RAIN OVER THE SOUTHERN PORTIONS OF THE CWA...WITH SOME LIGHT SNOW POSSIBLE OVER THE NRN LOCATIONS. THERE MAY BE A BRIEF TRANSITION OVER TO ALL LIGHT SNOW WEDNESDAY NIGHT...BEFORE THE NRN STREAM SYSTEM SCOOTS OFF TO THE EAST. THE NEXT SIGNIFICANT CHANCE FOR PCPN WILL NOT BE UNTIL LATE IN THE EXTENDED PERIOD...AND WILL BE ASSOCIATED WITH THE SRN STREAM SYSTEM. THE GFS AND ECMWF ARE IN DECENT ENOUGH AGREEMENT ON THIS SYSTEM...THOUGH THE ECMWF IS A BIT FASTER AND HAS A GREATER DEGREE OF PHASING WITH THE NRN STREAM THAN THE GFS...WHICH INDICATES MORE OF A CUT OFF LOW AND...CONSEQUENTLY... IS MORE SLOWLY PROGRESSIVE. DEPENDING ON WHETHER THE FASTER OR THE SLOW SOLUTION VERIFIES...WE COULD SEE PCPN MOVING BACK INTO THE AREA AS EARLY AS THURSDAY PER THE ECMWF OR FRIDAY PER THE GFS. AT THIS POINT...HAVE GONE WITH A MORE MIDDLE OF THE ROAD APPROACH FOR THE LATE EXTENDED PERIOD POPS...WITH SLIGHT CHANCE POPS FOR THURSDAY NIGHT AND CHANCE POPS FOR FRIDAY. KREIN && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 00Z... * MODERATE/HEAVY SNOW DIMINISHING EARLY THIS EVENING. * MVFR VIS/CIG CONDITIONS IN LINGERING LIGHTER SNOW REMAINDER OF EVENING HOURS. * POTENTIAL FOR LAKE-INDUCED SNOW SHOWERS AT TIMES THROUGH SATURDAY MORNING. RATZER //DISCUSSION...UPDATED 00Z... SNOW BEGINNING TO WIND DOWN FROM THE WEST/NORTHWEST CURRENTLY... WITH RADAR INDICATING HIGHER REFLECTIVITY IN HEAVIER SNOW NOW SOUTH OF KORD. VISIBILITY INCREASING BETTER THAN A MILE GENERALLY NORTHWEST OF A VYS-DPA-ORD LINE AND THIS SHOULD WORK INTO THE CHICAGO AREA TERMINALS IN THE NEXT 2-3 HOURS. KMDW AND KGYY STILL EXPECTED TO SEE SOME 1/2SM TO 1/4SM VIS EARLY...THOUGH MODELS DEPICT RELATIVELY RAPID LOSS OF STRONGER LIFT BEYOND 00-02Z. OUTSIDE OF THE HEAVIER SNOW...CEILINGS GENERALLY MVFR...SO SHOULD SEE FAIRLY RAPID IMPROVEMENT FROM LIFR/IFR CONDITIONS THROUGH EARLY THIS EVENING. OTHER CONCERN IS LAKE-INDUCED SNOW SHOWERS WHICH CURRENTLY CAN BE SEEN ON RADAR IN A LITTLE CONVERGENT BAND OFF KUGN. HIGH RES MODELS INCLUDING RECENT RUC/HRRR RUNS INDICATE THIS CONVERGENT BAND WILL EVENTUALLY SPREAD SOUTHEAST INTO THE PWK/ORD/DPA AREAS DURING THE LATER OVERNIGHT HOURS...AND MAY IMPACT SOME OF THE CHICAGO TAF SITES WITH SOME LIGHT SNOW THROUGH SATURDAY MORNING BEFORE WINDS SHIFT MORE EAST/SOUTHEAST IN THE AFTERNOON. FORECAST SOUNDINGS DEPICT POTENTIAL FOR RELATIVELY SHALLOW LAKE CONVECTION SO NOT EXPECTING SIGNIFICANT ACCUMULATIONS OR VIS REDUCTIONS... BUT WILL HAVE TO MONITOR. AND OF COURSE...EXACT PLACEMENT OF NARROW BAND DIFFICULT AT THIS TIME. WINDS...GENERALLY NORTHEAST THROUGH MIDDAY SATURDAY THOUGH THERE MAY BE A LITTLE VARIABILITY BETWEEN ENE AND NNE THIS EVENING WITH WEAK INVERTED TROUGH ALONG THE WEST SHORE OF LAKE MICHIGAN. SURFACE HIGH BUILDS ACROSS THE AREA BY EARLY SATURDAY AFTERNOON RESULTING IN WINDS EVENTUALLY VEERING BACK TO ESE. RATZER //ORD AND MDW CONFIDENCE...UPDATED 00Z... * HIGH CONFIDENCE IN LOSS OF LIFR/IFR AND IMPROVING TRENDS IN VIS/CIG THIS EVENING. * MEDIUM CONFIDENCE IN WIND TRENDS THIS EVENING. * HIGH CONFIDENCE IN CONTINUED LAKE INDUCED SNOW SHOWERS OVER NORTHEAST IL LATER TONIGHT/SATURDAY MORNING...BUT LOW CONFIDENCE ON SPECIFIC TIMING AND PLACEMENT. RATZER //OUTLOOK FOR ORD/MDW FOR 12Z SUNDAY-12Z FRIDAY...UPDATED 00Z... SUNDAY...CHANCE OF RAIN OR DRIZZLE. MVFR PROBABLE WITH IFR CEILINGS/VIS. MONDAY...CHANCE OF RAIN OR SNOW. MVFR POSSIBLE. TUESDAY...VFR. WEDNESDAY...CHANCE OF RAIN OR SNOW...OTHERWISE VFR. THURSDAY...SLGT CHANCE OF LGT SNOW...OTHERWISE VFR. RATZER && .MARINE... 316 PM CST TWO LOW PRESSURE SYSTEMS...ONE OVER ONTARIO AND ONE IN THE OHIO VALLEY...WILL FIGHT FOR INFLUENCE OVER THE LAKE THIS EVENING. THIS WILL RESULT IN VARIABLE WINDS FOR A WHILE...WHICH EVENTUALLY TURN NORTHWEST OVER THE NORTH HALF AND NORTHEAST OVER THE SOUTH AHEAD OF AN APPROACHING CENTER OF HIGH PRESSURE. WINDS GO LIGHT AND VARIABLE AS THE HIGH PRESSURE MOVES ACROSS THE LAKE TOMORROW. BY SUNDAY A NEW LOW PRESSURE SYSTEM AND TRAILING COLD FRONT APPROACH FROM THE WEST. DECISION TO POST A GALE WATCH FOR SUNDAY WAS BASED ON EXPECTATION OF STRONG SOUTH WINDS AHEAD OF THE FRONT...GUSTING INTO THE 35 KT RANGE. ACTUALLY FEEL STRONGER WINDS WILL ARRIVE MONDAY AFTER THE FRONT PASSES AND WINDS TURN WEST. THESE ALSO WILL HAVE THE ADVANTAGE OF BEING COLDER AND IN A MORE WELL MIXED AIRMASS...THUS SUPPORTING BETTER MIXING OF GUSTS TO THE LAKE SURFACE. AT THIS POINT THE REST OF NEXT WEEK LOOKS RELATIVELY QUIET...FOR NOW. LENNING && .LOT WATCHES/WARNINGS/ADVISORIES... IL...NONE. IN...WINTER WEATHER ADVISORY...INZ001-INZ002-INZ010-INZ011-INZ019 UNTIL MIDNIGHT SATURDAY. LM...GALE WATCH...LMZ080-LMZ261-LMZ362-LMZ364-LMZ366-LMZ563-LMZ565- LMZ567-LMZ669-LMZ671-LMZ673-LMZ675-LMZ777-LMZ779-LMZ868- LMZ870-LMZ872-LMZ874-LMZ876-LMZ878...3 AM SUNDAY TO 9 PM SUNDAY. && $$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
658 PM CST FRI JAN 20 2012 .DISCUSSION...UPDATED 655 PM CST THE HEAVIEST OF SNOWFALL IS BEGINNING TO SHIFT EAST OF THE AREA WITH MOST LOCATIONS AT OR ABOVE 1/2 TO 1 MILE VIS. THE EARLIER HEAVY BANDING LINED UP NICELY WITH AN AREA OF RUC ANALYZED FGEN WITHIN THE H85 TO H7 LAYER. THAT AREA WILL CONTINUE TO WEAKEN AND SHIFT EAST - AND NOT EXPECTING ANY FURTHER SIGNIFICANT REDUCTIONS TO VIS OR INCH PER HOUR SNOWFALL THOUGH THE EVENING. THE BACK EDGE OF THE PRECIP IS NOTED BASICALLY NOTED FROM WHITEWATER WISCONSIN...SOUTHWEST THROUGH FREEPORT ILLINOIS. PRESENT WSW GOES THROUGH 03Z FOR THE NORTHWESTERN TIER OF COUNTIES...AND MAY BEGIN TO PULL COUNTIES EARLIER AS THE BACK EDGE MOVES THROUGH. FOR COUNTIES EAST...STILL EXPECT THE SNOWFALL TO DECREASE THROUGH THE EVENING WITH ONLY MINOR ACCUMULATIONS FOR AREAS WEST OTHE 355/57 CORRIDOR...AND ANOTHER INCH OR SO FOR LOCATIONS ALONG THE ILLINOIS/INDIANA BORDER AND EAST. SHEA .PREVIOUS DISCUSSION... 344 PM CST NO MAJOR SURPRISES SO FAR...DID EXPAND THE WINTER STORM WARNING INTO LEE COUNTY THIS AFTERNOON WHICH HAS SEEN PROLONGED PERIOD OF HEAVIER SNOWFALL WITH DECENT RETURNS STILL UPSTREAM. KENDALL AND WILL COUNTIES WILL BE CLOSE TO WARNING CRITERIA OF 6" AS AXIS OF MAXIMUM SNOW SETS UP PRETTY MUCH AS EXPECTED BETWEEN THE I-90 AND I-80 CORRIDORS WITH RATES OF AN INCH AN HOUR...OCCASIONALLY 1.5 INCHES PER HOUR. EXPECT INTENSITIES TO PEAK ACROSS THE CHICAGO METRO AREA THROUGH THE EARLY EVENING. DID GET OFF TO A SLOWER START THAN EXPECTED AND SNOW:LIQUID RATIOS HAVE BEEN A BIT LOWER THAN ORIGINALLY ANTICIPATED...SO FOR NOW BELIEVE DESPITE THE AXIS SETTING UP FARTHER SOUTH THAN THE ORIGINAL WARNING AREA...THAT ADVISORY FOR 4 TO 6 INCHES ACROSS KENDALL/WILL COUNTIES AND LAKE COUNTY INDIANA WILL STAND //THOUGH MAY SEE SOME LOCALIZED AREAS AT OR JUST ABOVE 6 INCHES PARTICULARLY ACROSS FAR NORTHERN WILL COUNTY//. WIDESPREAD VSBY OF 1/4 MILE OR LESS HAS BEEN REPORTED AND INTERMITTENT PERIODS OF HEAVY SNOW CONTINUE SO ROADWAYS WILL BE A MESS THROUGH THE EVENING HOURS. SATURDAY THROUGH FRIDAY... SHORT TERM...SATURDAY THROUGH MONDAY...FOLLOWING THE PASSAGE OF THE MID LEVEL SYSTEM RESPONSIBLE FOR THE SYNOPTIC SNOW...THE INITIAL FORECAST CONCERN WILL FOCUS ON THE POTENTIAL FOR A LAKE EFFECT BAND OF SNOW MOVING INTO NERN IL. ALL OF THE GUIDANCE IS INDICATING LAKE SFC-850MB DELTA-T AROUND 15C OVER SOUTHERN LAKE MICHIGAN...WHICH WOULD BE CONDUCIVE TO LAKE EFFECT SNOW DEVELOPMENT. THE HIGH RES WRF-ARW/NMM WITH SUPPORT OF THE OPERATIONAL NAM12...ALL INDICATE A CONVERGENCE BAND FORMING OVER SOUTHERN LAKE MICHIGAN...WITH THE POSSIBILITY OF MESOVORTEX DEVELOPMENT WITHIN THE CONVERGENCE ZONE AND INVERTED TROUGH. WITH TIME...THE BAND SHOULD GRADUALLY MOVE INLAND AND TO THE NORTHWEST...POSSIBLE AFFECTING PORTIONS OF NERN AND NCNTRL IL. CONCURRENTLY...LAKE SFC-850MB DELTA T VALUES WILL BE ON THE DECREASE. SO...EXPECT MORE OF AN ADVECTING BAND OF LAKE EFFECT SNOW THAN CONTINUOUS PRODUCTION OF LAKE EFFECT SNOW OVER THE IMMEDIATE LAKE FRONT LOCATIONS. AT THIS TIME...HAVE OPTED TO DEPICT THIS LAKE EFFECT BAND IN THE GRIDDED FORECAST GRAPHICS WITH AN AREA OF CHANCE TO SLIGHT CHANCE POPS WITH -SHSN. THERE IS CERTAINLY THE POTENTIAL FOR ADDITIONAL ACCUMULATING SNOW WITH THE MAIN CONVERGENCE AREA...BUT DUE TO THE MESOSCALE NATURE OF ANY POSSIBLE MESOVORTEX DEVELOPMENT...IT IS NOT POSSIBLE TO PINPOINT ANY POSSIBLE HEAVIER LAKE EFFECT SNOW WITH THIS FEATURE...WHICH WOULD NEED TO BE HANDLED WITH A NEAR TERM FORECAST UPDATE TOMORROW. ON A LARGER SCALE...HIGH PRESSURE SHOULD BUILD OVER THE AREA BRINGING DECREASING CLOUD COVER. TO START OUT SATURDAY MORNING...TEMPERATURES SHOULD RANGE FROM THE LOWER SINGLE DIGITS OVER THE NWRN PORTIONS OF THE CWA...WHERE SKIES SHOULD CLEAR THE EARLIEST AND THE GREATEST AMOUNT OF RADIATING SHOULD OCCUR...TO THE UPPER TEENS ALONG THE LAKE FRONT...WHERE THERE SHOULD BE THE GREATEST AMOUNT OF RESIDUAL CLOUD COVER. WITH AT LEAST PARTIAL SUNSHINE AND AN END TO SUSTAINED COLD ADVECTION OVER THE AREA ON SATURDAY...TEMPERATURES SHOULD SHOULD REBOUND INTO THE LOWER TO MIDDLE 20S. BY SUNDAY...THE HIGH WILL MOVE OFF TO THE EAST. A MORE COMPLICATED SITUATION WILL BE SETTING UP TO THE WEST OF THE LOCAL AREA BY SUNDAY. STRONG NORTHERN AND SOUTHERN STREAM SHORTWAVES ARE EXPECTED TO EJECT OUT OF THE ROCKIES BY SUNDAY MORNING...WITH A LARGE AREA OF LOW PRESSURE DEVELOPING OVER THE CENTRAL PLAINS. THIS WILL INITIATE STRONG WARM/MOIST ADVECTION INTO THE MIDWEST. THE MODELS ARE INDICATING PHASING OF THE NORTHERN AND SOUTHERN STREAMS...WITH A CONSOLIDATED SFC LOW FORMING OVER LOWER MICHIGAN BY MONDAY MORNING. THE MAIN CHANGE TO THE GOING FORECAST WITH RESPECT TO THIS SYSTEM IS TO SPEED UP THE PROGRESSION WITH A COLD FRONTAL PASSAGE LATE SUNDAY NIGHT OR EARLY MONDAY MORNING. WITH THE STRONG WARM ADVECTION...ASSOCIATED PCPN WILL START OUT IN LIQUID FORM AS TEMPERATURES CLIMB INTO THE UPPER 30S TO LOWER 40S THROUGH THE DAY...WITH TEMPERATURES REMAINING NEARLY STEADY INTO THE NIGHT. TEMPERATURES WILL NOT DROP OFF UNTIL AFTER THE FROPA...WHEN TEMPERATURES WILL DROP INTO THE LOWER 20S OVER THE ROCKFORD AREA. FARTHER SOUTHEAST...SOUTH OF THE KANKAKEE VALLEY...TEMPS WILL ONLY DROP INTO THE MIDDLE 30S SO A CHANGEOVER FROM RAIN TO SNOW MAY NOT OCCUR UNTIL LATE IN THE DAY. IT IS EVEN POSSIBLE THAT TEMPS OVER BENTON/JASPER/NEWTON COUNTY AREA MAY NOT COOL OFF ENOUGH BEFORE THE SYSTEM LIFTS OUT LATE MONDAY TO EVER SEE ANY ADDITIONAL SNOW. EXTENDED FORECAST...TUESDAY THROUGH FRIDAY...CONDITIONS SHOULD QUIET DOWN CONSIDERABLY THROUGH THE EXTENDED FORECAST PERIOD. BY TUESDAY...HIGH PRESSURE WILL ONCE AGAIN DOMINATE THE REGION. A SPLIT FLOW PATTERN IS EXPECTED TO DEVELOP WITH AN ACTIVE NORTHERN STREAM FOCUSED ALONG THE CANADIAN BORDER WHILE AN ACTIVE SOUTH STREAM WILL BE FOCUSED ALONG THE RED RIVER VALLEY AND OHIO VALLEY. IN BETWEEN THESE TWO STREAMS...THE MIDDLE MISSISSIPPI VALLEY AND MIDWEST WILL REMAIN UNDER A WEAK RIDGE OF HIGH PRESSURE. THE BEST CHANCE FOR ANY PCPN BETWEEN EARLY TUESDAY AND EARLY FRIDAY WILL BE ON WEDNESDAY WHEN THE NRN STREAM SYSTEM WILL BE PASSING THROUGH THE UPPER GREAT LAKES AND STRONG WARM ADVECTION DEVELOPS OVER THE LOWER AND MIDDLE MISSISSIPPI VALLEY AND SPREADING INTO SOUTHERN IL/IN. BETWEEN THESE TWO SYSTEM...THERE IS A CHANCE FOR SOME LIGHT RAIN OVER THE SOUTHERN PORTIONS OF THE CWA...WITH SOME LIGHT SNOW POSSIBLE OVER THE NRN LOCATIONS. THERE MAY BE A BRIEF TRANSITION OVER TO ALL LIGHT SNOW WEDNESDAY NIGHT...BEFORE THE NRN STREAM SYSTEM SCOOTS OFF TO THE EAST. THE NEXT SIGNIFICANT CHANCE FOR PCPN WILL NOT BE UNTIL LATE IN THE EXTENDED PERIOD...AND WILL BE ASSOCIATED WITH THE SRN STREAM SYSTEM. THE GFS AND ECMWF ARE IN DECENT ENOUGH AGREEMENT ON THIS SYSTEM...THOUGH THE ECMWF IS A BIT FASTER AND HAS A GREATER DEGREE OF PHASING WITH THE NRN STREAM THAN THE GFS...WHICH INDICATES MORE OF A CUT OFF LOW AND...CONSEQUENTLY... IS MORE SLOWLY PROGRESSIVE. DEPENDING ON WHETHER THE FASTER OR THE SLOW SOLUTION VERIFIES...WE COULD SEE PCPN MOVING BACK INTO THE AREA AS EARLY AS THURSDAY PER THE ECMWF OR FRIDAY PER THE GFS. AT THIS POINT...HAVE GONE WITH A MORE MIDDLE OF THE ROAD APPROACH FOR THE LATE EXTENDED PERIOD POPS...WITH SLIGHT CHANCE POPS FOR THURSDAY NIGHT AND CHANCE POPS FOR FRIDAY. KREIN && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 00Z... * MODERATE/HEAVY SNOW DIMINISHING EARLY THIS EVENING. * MVFR VIS/CIG CONDITIONS IN LINGERING LIGHTER SNOW REMAINDER OF EVENING HOURS. * POTENTIAL FOR LAKE-INDUCED SNOW SHOWERS AT TIMES THROUGH SATURDAY MORNING. RATZER //DISCUSSION...UPDATED 00Z... SNOW BEGINNING TO WIND DOWN FROM THE WEST/NORTHWEST CURRENTLY... WITH RADAR INDICATING HIGHER REFLECTIVITY IN HEAVIER SNOW NOW SOUTH OF KORD. VISIBILITY INCREASING BETTER THAN A MILE GENERALLY NORTHWEST OF A VYS-DPA-ORD LINE AND THIS SHOULD WORK INTO THE CHICAGO AREA TERMINALS IN THE NEXT 2-3 HOURS. KMDW AND KGYY STILL EXPECTED TO SEE SOME 1/2SM TO 1/4SM VIS EARLY...THOUGH MODELS DEPICT RELATIVELY RAPID LOSS OF STRONGER LIFT BEYOND 00-02Z. OUTSIDE OF THE HEAVIER SNOW...CEILINGS GENERALLY MVFR...SO SHOULD SEE FAIRLY RAPID IMPROVEMENT FROM LIFR/IFR CONDITIONS THROUGH EARLY THIS EVENING. OTHER CONCERN IS LAKE-INDUCED SNOW SHOWERS WHICH CURRENTLY CAN BE SEEN ON RADAR IN A LITTLE CONVERGENT BAND OFF KUGN. HIGH RES MODELS INCLUDING RECENT RUC/HRRR RUNS INDICATE THIS CONVERGENT BAND WILL EVENTUALLY SPREAD SOUTHEAST INTO THE PWK/ORD/DPA AREAS DURING THE LATER OVERNIGHT HOURS...AND MAY IMPACT SOME OF THE CHICAGO TAF SITES WITH SOME LIGHT SNOW THROUGH SATURDAY MORNING BEFORE WINDS SHIFT MORE EAST/SOUTHEAST IN THE AFTERNOON. FORECAST SOUNDINGS DEPICT POTENTIAL FOR RELATIVELY SHALLOW LAKE CONVECTION SO NOT EXPECTING SIGNIFICANT ACCUMULATIONS OR VIS REDUCTIONS... BUT WILL HAVE TO MONITOR. AND OF COURSE...EXACT PLACEMENT OF NARROW BAND DIFFICULT AT THIS TIME. WINDS...GENERALLY NORTHEAST THROUGH MIDDAY SATURDAY THOUGH THERE MAY BE A LITTLE VARIABILITY BETWEEN ENE AND NNE THIS EVENING WITH WEAK INVERTED TROUGH ALONG THE WEST SHORE OF LAKE MICHIGAN. SURFACE HIGH BUILDS ACROSS THE AREA BY EARLY SATURDAY AFTERNOON RESULTING IN WINDS EVENTUALLY VEERING BACK TO ESE. RATZER //ORD AND MDW CONFIDENCE...UPDATED 00Z... * HIGH CONFIDENCE IN LOSS OF LIFR/IFR AND IMPROVING TRENDS IN VIS/CIG THIS EVENING. * MEDIUM CONFIDENCE IN WIND TRENDS THIS EVENING. * HIGH CONFIDENCE IN CONTINUED LAKE INDUCED SNOW SHOWERS OVER NORTHEAST IL LATER TONIGHT/SATURDAY MORNING...BUT LOW CONFIDENCE ON SPECIFIC TIMING AND PLACEMENT. RATZER //OUTLOOK FOR ORD/MDW FOR 12Z SUNDAY-12Z FRIDAY...UPDATED 00Z... SUNDAY...CHANCE OF RAIN OR DRIZZLE. MVFR PROBABLE WITH IFR CEILINGS/VIS. MONDAY...CHANCE OF RAIN OR SNOW. MVFR POSSIBLE. TUESDAY...VFR. WEDNESDAY...CHANCE OF RAIN OR SNOW...OTHERWISE VFR. THURSDAY...SLGT CHANCE OF LGT SNOW...OTHERWISE VFR. RATZER && .MARINE... 316 PM CST TWO LOW PRESSURE SYSTEMS...ONE OVER ONTARIO AND ONE IN THE OHIO VALLEY...WILL FIGHT FOR INFLUENCE OVER THE LAKE THIS EVENING. THIS WILL RESULT IN VARIABLE WINDS FOR A WHILE...WHICH EVENTUALLY TURN NORTHWEST OVER THE NORTH HALF AND NORTHEAST OVER THE SOUTH AHEAD OF AN APPROACHING CENTER OF HIGH PRESSURE. WINDS GO LIGHT AND VARIABLE AS THE HIGH PRESSURE MOVES ACROSS THE LAKE TOMORROW. BY SUNDAY A NEW LOW PRESSURE SYSTEM AND TRAILING COLD FRONT APPROACH FROM THE WEST. DECISION TO POST A GALE WATCH FOR SUNDAY WAS BASED ON EXPECTATION OF STRONG SOUTH WINDS AHEAD OF THE FRONT...GUSTING INTO THE 35 KT RANGE. ACTUALLY FEEL STRONGER WINDS WILL ARRIVE MONDAY AFTER THE FRONT PASSES AND WINDS TURN WEST. THESE ALSO WILL HAVE THE ADVANTAGE OF BEING COLDER AND IN A MORE WELL MIXED AIRMASS...THUS SUPPORTING BETTER MIXING OF GUSTS TO THE LAKE SURFACE. AT THIS POINT THE REST OF NEXT WEEK LOOKS RELATIVELY QUIET...FOR NOW. LENNING && .LOT WATCHES/WARNINGS/ADVISORIES... IL...WINTER STORM WARNING...ILZ003-ILZ004-ILZ008-ILZ010-ILZ011 UNTIL 9 PM FRIDAY. WINTER STORM WARNING...ILZ005-ILZ006-ILZ012-ILZ013-ILZ014 UNTIL MIDNIGHT SATURDAY. WINTER WEATHER ADVISORY...ILZ019-ILZ020-ILZ021-ILZ022-ILZ023 UNTIL MIDNIGHT SATURDAY. IN...WINTER WEATHER ADVISORY...INZ001-INZ002-INZ010-INZ011-INZ019 UNTIL MIDNIGHT SATURDAY. LM...GALE WATCH...LMZ080-LMZ261-LMZ362-LMZ364-LMZ366-LMZ563-LMZ565- LMZ567-LMZ669-LMZ671-LMZ673-LMZ675-LMZ777-LMZ779-LMZ868- LMZ870-LMZ872-LMZ874-LMZ876-LMZ878...3 AM SUNDAY TO 9 PM SUNDAY. && $$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
655 PM CST FRI JAN 20 2012 .DISCUSSION... 655 PM CST THE HEAVIEST OF SNOWFALL IS BEGINNING TO SHIFT EAST OF THE AREA WITH MOST LOCATIONS AT OR ABOVE 1/2 TO 1 MILE VIS. THE EARLIER HEAVY BANDING LINED UP NICELY WITH AN AREA OF RUC ANALYZED FGEN WITHIN THE H85 TO H7 LAYER. THAT AREA WILL CONTINUE TO WEAKEN AND SHIFT EAST - AND NOT EXPECTING ANY FURTHER SIGNIFICANT REDUCTIONS TO VIS OR INCH PER HOUR SNOWFALL THOUGH THE EVENING. THE BACK EDGE OF THE PRECIP IS NOTED BASICALLY NOTED FROM WHITEWATER WISCONSIN...SOUTHWEST THROUGH FREEPORT ILLINOIS. PRESENT WSW GOES THROUGH 03Z FOR THE NORTHWESTERN TIER OF COUNTIES...AND MAY BEGIN TO PULL COUNTIES EARLIER AS THE BACK EDGE MOVES THROUGH. FOR COUNTIES EAST...STILL EXPECT THE SNOWFALL TO DECREASE THROUGH THE EVENING WITH ONLY MINOR ACCUMULATIONS FOR AREAS WEST OTHE 355/57 CORRIDOR...AND ANOTHER INCH OR SO FOR LOCATIONS ALONG THE ILLINOIS/INDIANA BORDER AND EAST..DISCUSSION... SHEA .DISCUSSION... 344 PM CST NO MAJOR SURPRISES SO FAR...DID EXPAND THE WINTER STORM WARNING INTO LEE COUNTY THIS AFTERNOON WHICH HAS SEEN PROLONGED PERIOD OF HEAVIER SNOWFALL WITH DECENT RETURNS STILL UPSTREAM. KENDALL AND WILL COUNTIES WILL BE CLOSE TO WARNING CRITERIA OF 6" AS AXIS OF MAXIMUM SNOW SETS UP PRETTY MUCH AS EXPECTED BETWEEN THE I-90 AND I-80 CORRIDORS WITH RATES OF AN INCH AN HOUR...OCCASIONALLY 1.5 INCHES PER HOUR. EXPECT INTENSITIES TO PEAK ACROSS THE CHICAGO METRO AREA THROUGH THE EARLY EVENING. DID GET OFF TO A SLOWER START THAN EXPECTED AND SNOW:LIQUID RATIOS HAVE BEEN A BIT LOWER THAN ORIGINALLY ANTICIPATED...SO FOR NOW BELIEVE DESPITE THE AXIS SETTING UP FARTHER SOUTH THAN THE ORIGINAL WARNING AREA...THAT ADVISORY FOR 4 TO 6 INCHES ACROSS KENDALL/WILL COUNTIES AND LAKE COUNTY INDIANA WILL STAND //THOUGH MAY SEE SOME LOCALIZED AREAS AT OR JUST ABOVE 6 INCHES PARTICULARLY ACROSS FAR NORTHERN WILL COUNTY//. WIDESPREAD VSBY OF 1/4 MILE OR LESS HAS BEEN REPORTED AND INTERMITTENT PERIODS OF HEAVY SNOW CONTINUE SO ROADWAYS WILL BE A MESS THROUGH THE EVENING HOURS. .DISCUSSION FOR SATURDAY THROUGH FRIDAY... 335 PM CST... SHORT TERM...SATURDAY THROUGH MONDAY...FOLLOWING THE PASSAGE OF THE MID LEVEL SYSTEM RESPONSIBLE FOR THE SYNOPTIC SNOW...THE INITIAL FORECAST CONCERN WILL FOCUS ON THE POTENTIAL FOR A LAKE EFFECT BAND OF SNOW MOVING INTO NERN IL. ALL OF THE GUIDANCE IS INDICATING LAKE SFC-850MB DELTA-T AROUND 15C OVER SOUTHERN LAKE MICHIGAN...WHICH WOULD BE CONDUCIVE TO LAKE EFFECT SNOW DEVELOPMENT. THE HIGH RES WRF-ARW/NMM WITH SUPPORT OF THE OPERATIONAL NAM12...ALL INDICATE A CONVERGENCE BAND FORMING OVER SOUTHERN LAKE MICHIGAN...WITH THE POSSIBILITY OF MESOVORTEX DEVELOPMENT WITHIN THE CONVERGENCE ZONE AND INVERTED TROUGH. WITH TIME...THE BAND SHOULD GRADUALLY MOVE INLAND AND TO THE NORTHWEST...POSSIBLE AFFECTING PORTIONS OF NERN AND NCNTRL IL. CONCURRENTLY...LAKE SFC-850MB DELTA T VALUES WILL BE ON THE DECREASE. SO...EXPECT MORE OF AN ADVECTING BAND OF LAKE EFFECT SNOW THAN CONTINUOUS PRODUCTION OF LAKE EFFECT SNOW OVER THE IMMEDIATE LAKE FRONT LOCATIONS. AT THIS TIME...HAVE OPTED TO DEPICT THIS LAKE EFFECT BAND IN THE GRIDDED FORECAST GRAPHICS WITH AN AREA OF CHANCE TO SLIGHT CHANCE POPS WITH -SHSN. THERE IS CERTAINLY THE POTENTIAL FOR ADDITIONAL ACCUMULATING SNOW WITH THE MAIN CONVERGENCE AREA...BUT DUE TO THE MESOSCALE NATURE OF ANY POSSIBLE MESOVORTEX DEVELOPMENT...IT IS NOT POSSIBLE TO PINPOINT ANY POSSIBLE HEAVIER LAKE EFFECT SNOW WITH THIS FEATURE...WHICH WOULD NEED TO BE HANDLED WITH A NEAR TERM FORECAST UPDATE TOMORROW. ON A LARGER SCALE...HIGH PRESSURE SHOULD BUILD OVER THE AREA BRINGING DECREASING CLOUD COVER. TO START OUT SATURDAY MORNING...TEMPERATURES SHOULD RANGE FROM THE LOWER SINGLE DIGITS OVER THE NWRN PORTIONS OF THE CWA...WHERE SKIES SHOULD CLEAR THE EARLIEST AND THE GREATEST AMOUNT OF RADIATING SHOULD OCCUR...TO THE UPPER TEENS ALONG THE LAKE FRONT...WHERE THERE SHOULD BE THE GREATEST AMOUNT OF RESIDUAL CLOUD COVER. WITH AT LEAST PARTIAL SUNSHINE AND AN END TO SUSTAINED COLD ADVECTION OVER THE AREA ON SATURDAY...TEMPERATURES SHOULD SHOULD REBOUND INTO THE LOWER TO MIDDLE 20S. BY SUNDAY...THE HIGH WILL MOVE OFF TO THE EAST. A MORE COMPLICATED SITUATION WILL BE SETTING UP TO THE WEST OF THE LOCAL AREA BY SUNDAY. STRONG NORTHERN AND SOUTHERN STREAM SHORTWAVES ARE EXPECTED TO EJECT OUT OF THE ROCKIES BY SUNDAY MORNING...WITH A LARGE AREA OF LOW PRESSURE DEVELOPING OVER THE CENTRAL PLAINS. THIS WILL INITIATE STRONG WARM/MOIST ADVECTION INTO THE MIDWEST. THE MODELS ARE INDICATING PHASING OF THE NORTHERN AND SOUTHERN STREAMS...WITH A CONSOLIDATED SFC LOW FORMING OVER LOWER MICHIGAN BY MONDAY MORNING. THE MAIN CHANGE TO THE GOING FORECAST WITH RESPECT TO THIS SYSTEM IS TO SPEED UP THE PROGRESSION WITH A COLD FRONTAL PASSAGE LATE SUNDAY NIGHT OR EARLY MONDAY MORNING. WITH THE STRONG WARM ADVECTION...ASSOCIATED PCPN WILL START OUT IN LIQUID FORM AS TEMPERATURES CLIMB INTO THE UPPER 30S TO LOWER 40S THROUGH THE DAY...WITH TEMPERATURES REMAINING NEARLY STEADY INTO THE NIGHT. TEMPERATURES WILL NOT DROP OFF UNTIL AFTER THE FROPA...WHEN TEMPERATURES WILL DROP INTO THE LOWER 20S OVER THE ROCKFORD AREA. FARTHER SOUTHEAST...SOUTH OF THE KANKAKEE VALLEY...TEMPS WILL ONLY DROP INTO THE MIDDLE 30S SO A CHANGEOVER FROM RAIN TO SNOW MAY NOT OCCUR UNTIL LATE IN THE DAY. IT IS EVEN POSSIBLE THAT TEMPS OVER BENTON/JASPER/NEWTON COUNTY AREA MAY NOT COOL OFF ENOUGH BEFORE THE SYSTEM LIFTS OUT LATE MONDAY TO EVER SEE ANY ADDITIONAL SNOW. EXTENDED FORECAST...TUESDAY THROUGH FRIDAY...CONDITIONS SHOULD QUIET DOWN CONSIDERABLY THROUGH THE EXTENDED FORECAST PERIOD. BY TUESDAY...HIGH PRESSURE WILL ONCE AGAIN DOMINATE THE REGION. A SPLIT FLOW PATTERN IS EXPECTED TO DEVELOP WITH AN ACTIVE NORTHERN STREAM FOCUSED ALONG THE CANADIAN BORDER WHILE AN ACTIVE SOUTH STREAM WILL BE FOCUSED ALONG THE RED RIVER VALLEY AND OHIO VALLEY. IN BETWEEN THESE TWO STREAMS...THE MIDDLE MISSISSIPPI VALLEY AND MIDWEST WILL REMAIN UNDER A WEAK RIDGE OF HIGH PRESSURE. THE BEST CHANCE FOR ANY PCPN BETWEEN EARLY TUESDAY AND EARLY FRIDAY WILL BE ON WEDNESDAY WHEN THE NRN STREAM SYSTEM WILL BE PASSING THROUGH THE UPPER GREAT LAKES AND STRONG WARM ADVECTION DEVELOPS OVER THE LOWER AND MIDDLE MISSISSIPPI VALLEY AND SPREADING INTO SOUTHERN IL/IN. BETWEEN THESE TWO SYSTEM...THERE IS A CHANCE FOR SOME LIGHT RAIN OVER THE SOUTHERN PORTIONS OF THE CWA...WITH SOME LIGHT SNOW POSSIBLE OVER THE NRN LOCATIONS. THERE MAY BE A BRIEF TRANSITION OVER TO ALL LIGHT SNOW WEDNESDAY NIGHT...BEFORE THE NRN STREAM SYSTEM SCOOTS OFF TO THE EAST. THE NEXT SIGNIFICANT CHANCE FOR PCPN WILL NOT BE UNTIL LATE IN THE EXTENDED PERIOD...AND WILL BE ASSOCIATED WITH THE SRN STREAM SYSTEM. THE GFS AND ECMWF ARE IN DECENT ENOUGH AGREEMENT ON THIS SYSTEM...THOUGH THE ECMWF IS A BIT FASTER AND HAS A GREATER DEGREE OF PHASING WITH THE NRN STREAM THAN THE GFS...WHICH INDICATES MORE OF A CUT OFF LOW AND...CONSEQUENTLY... IS MORE SLOWLY PROGRESSIVE. DEPENDING ON WHETHER THE FASTER OR THE SLOW SOLUTION VERIFIES...WE COULD SEE PCPN MOVING BACK INTO THE AREA AS EARLY AS THURSDAY PER THE ECMWF OR FRIDAY PER THE GFS. AT THIS POINT...HAVE GONE WITH A MORE MIDDLE OF THE ROAD APPROACH FOR THE LATE EXTENDED PERIOD POPS...WITH SLIGHT CHANCE POPS FOR THURSDAY NIGHT AND CHANCE POPS FOR FRIDAY. KREIN //PREV DISCUSSION... 1059 AM CST LEVEL FGEN FORCING FARTHER TO THE NORTHEAST...BUT STILL DEALING WITH SATURATING THE DRIER LOW LEVEL AIR. MAIN CONCERNS WITH THE FORECAST FOR THIS AFTERNOON WILL BE DEALING WITH A SOUTHWARD TREND IN THE MODELS FOR AXIS OF HEAVIEST QPF AND COMPLEX PHASING/INTERACTIONS WITH SOUTHERN LOW PRESSURE SYSTEM. MOST GUIDANCE HAS TRENDED THE AXIS OF HEAVIEST QPF SLIGHTLY FARTHER SOUTH...INTO PORTIONS OF NORTHERN WILL COUNTY AND KENDALL COUNTY. GUIDANCE ALSO IN GOOD AGREEMENT WITH OMEGAS PEAKING MID AFTERNOON INTO EARLY EVENING WITH RATES OF AN INCH PER HOUR POSSIBLE DURING THIS PERIOD...PARTICULARLY BETWEEN THE I-90 AND I-80 CORRIDORS. FOR TOTAL SNOWFALL TODAY...DID MODERATE FORECAST SNOW RATIOS A BIT...LOOKING AT AN AVERAGE OF 14-15:1 OVER SIX HOUR PERIOD THIS AFTERNOON...BUT AT LEAST TEMPORARILY WE COULD BE LOOKING AT HIGHER RATIOS FOR A SHORT WHILE. THIS WILL RESULT IN SNOW TOTALS OF 4 TO 7 INCHES PRETTY MUCH CENTERED DOWN THE I-88 CORRIDOR. WITH NO MAJOR CHANGES TO GOING FORECAST...WILL NOT MAKE ANY ADJUSTMENTS TO THE GOING WINTER WEATHER HEADLINES AT THIS TIME BUT DID SLIGHTLY BUMP UP SNOW TOTALS SOUTH OF THE CURRENT WARNED AREA...EXPECTING HIGHER END ADVISORY SNOWS ACROSS PORTIONS OF NORTHERN WILL COUNTY AND KENDALL COUNTY...AS WELL AS LAKE AND PORTER COUNTIES IN INDIANA. SECONDARY ISSUE WILL BE INTERACTIONS WITH A LOW PRESSURE SYSTEM MOVING ACROSS THE MID MISSISSIPPI VALLEY LATER THIS EVENING. GUIDANCE SUGGESTS THAT SOME OF THE STRONGER SYNOPTIC FORCING AS NOTED BY Q-VECTOR CONVERGENCE WILL SHIFT FARTHER SOUTH...WITH SOME GUIDANCE EVEN HINTING THAT HEAVIER SNOWS WILL SHIFT ACROSS THE SOUTHERN PORTION OF THE CWA. BASED ON MODELS POOR ABILITY TO HANDLE SUCH SITUATIONS...CONFIDENCE IS SOMEWHAT LOW ON HOW THINGS MAY PLAY OUT THIS EVENING...AND WILL HAVE TO MONITOR SHORT TERM TRENDS CLOSELY. BMD && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 00Z... * MODERATE/HEAVY SNOW DIMINISHING EARLY THIS EVENING. * MVFR VIS/CIG CONDITIONS IN LINGERING LIGHTER SNOW REMAINDER OF EVENING HOURS. * POTENTIAL FOR LAKE-INDUCED SNOW SHOWERS AT TIMES THROUGH SATURDAY MORNING. RATZER //DISCUSSION...UPDATED 00Z... SNOW BEGINNING TO WIND DOWN FROM THE WEST/NORTHWEST CURRENTLY... WITH RADAR INDICATING HIGHER REFLECTIVITY IN HEAVIER SNOW NOW SOUTH OF KORD. VISIBILITY INCREASING BETTER THAN A MILE GENERALLY NORTHWEST OF A VYS-DPA-ORD LINE AND THIS SHOULD WORK INTO THE CHICAGO AREA TERMINALS IN THE NEXT 2-3 HOURS. KMDW AND KGYY STILL EXPECTED TO SEE SOME 1/2SM TO 1/4SM VIS EARLY...THOUGH MODELS DEPICT RELATIVELY RAPID LOSS OF STRONGER LIFT BEYOND 00-02Z. OUTSIDE OF THE HEAVIER SNOW...CEILINGS GENERALLY MVFR...SO SHOULD SEE FAIRLY RAPID IMPROVEMENT FROM LIFR/IFR CONDITIONS THROUGH EARLY THIS EVENING. OTHER CONCERN IS LAKE-INDUCED SNOW SHOWERS WHICH CURRENTLY CAN BE SEEN ON RADAR IN A LITTLE CONVERGENT BAND OFF KUGN. HIGH RES MODELS INCLUDING RECENT RUC/HRRR RUNS INDICATE THIS CONVERGENT BAND WILL EVENTUALLY SPREAD SOUTHEAST INTO THE PWK/ORD/DPA AREAS DURING THE LATER OVERNIGHT HOURS...AND MAY IMPACT SOME OF THE CHICAGO TAF SITES WITH SOME LIGHT SNOW THROUGH SATURDAY MORNING BEFORE WINDS SHIFT MORE EAST/SOUTHEAST IN THE AFTERNOON. FORECAST SOUNDINGS DEPICT POTENTIAL FOR RELATIVELY SHALLOW LAKE CONVECTION SO NOT EXPECTING SIGNIFICANT ACCUMULATIONS OR VIS REDUCTIONS... BUT WILL HAVE TO MONITOR. AND OF COURSE...EXACT PLACEMENT OF NARROW BAND DIFFICULT AT THIS TIME. WINDS...GENERALLY NORTHEAST THROUGH MIDDAY SATURDAY THOUGH THERE MAY BE A LITTLE VARIABILITY BETWEEN ENE AND NNE THIS EVENING WITH WEAK INVERTED TROUGH ALONG THE WEST SHORE OF LAKE MICHIGAN. SURFACE HIGH BUILDS ACROSS THE AREA BY EARLY SATURDAY AFTERNOON RESULTING IN WINDS EVENTUALLY VEERING BACK TO ESE. RATZER //ORD AND MDW CONFIDENCE...UPDATED 00Z... * HIGH CONFIDENCE IN LOSS OF LIFR/IFR AND IMPROVING TRENDS IN VIS/CIG THIS EVENING. * MEDIUM CONFIDENCE IN WIND TRENDS THIS EVENING. * HIGH CONFIDENCE IN CONTINUED LAKE INDUCED SNOW SHOWERS OVER NORTHEAST IL LATER TONIGHT/SATURDAY MORNING...BUT LOW CONFIDENCE ON SPECIFIC TIMING AND PLACEMENT. RATZER //OUTLOOK FOR ORD/MDW FOR 12Z SUNDAY-12Z FRIDAY...UPDATED 00Z... SUNDAY...CHANCE OF RAIN OR DRIZZLE. MVFR PROBABLE WITH IFR CEILINGS/VIS. MONDAY...CHANCE OF RAIN OR SNOW. MVFR POSSIBLE. TUESDAY...VFR. WEDNESDAY...CHANCE OF RAIN OR SNOW...OTHERWISE VFR. THURSDAY...SLGT CHANCE OF LGT SNOW...OTHERWISE VFR. RATZER && .MARINE... 316 PM CST TWO LOW PRESSURE SYSTEMS...ONE OVER ONTARIO AND ONE IN THE OHIO VALLEY...WILL FIGHT FOR INFLUENCE OVER THE LAKE THIS EVENING. THIS WILL RESULT IN VARIABLE WINDS FOR A WHILE...WHICH EVENTUALLY TURN NORTHWEST OVER THE NORTH HALF AND NORTHEAST OVER THE SOUTH AHEAD OF AN APPROACHING CENTER OF HIGH PRESSURE. WINDS GO LIGHT AND VARIABLE AS THE HIGH PRESSURE MOVES ACROSS THE LAKE TOMORROW. BY SUNDAY A NEW LOW PRESSURE SYSTEM AND TRAILING COLD FRONT APPROACH FROM THE WEST. DECISION TO POST A GALE WATCH FOR SUNDAY WAS BASED ON EXPECTATION OF STRONG SOUTH WINDS AHEAD OF THE FRONT...GUSTING INTO THE 35 KT RANGE. ACTUALLY FEEL STRONGER WINDS WILL ARRIVE MONDAY AFTER THE FRONT PASSES AND WINDS TURN WEST. THESE ALSO WILL HAVE THE ADVANTAGE OF BEING COLDER AND IN A MORE WELL MIXED AIRMASS...THUS SUPPORTING BETTER MIXING OF GUSTS TO THE LAKE SURFACE. AT THIS POINT THE REST OF NEXT WEEK LOOKS RELATIVELY QUIET...FOR NOW. LENNING && .LOT WATCHES/WARNINGS/ADVISORIES... IL...WINTER STORM WARNING...ILZ003-ILZ004-ILZ008-ILZ010-ILZ011 UNTIL 9 PM FRIDAY. WINTER STORM WARNING...ILZ005-ILZ006-ILZ012-ILZ013-ILZ014 UNTIL MIDNIGHT SATURDAY. WINTER WEATHER ADVISORY...ILZ019-ILZ020-ILZ021-ILZ022-ILZ023 UNTIL MIDNIGHT SATURDAY. IN...WINTER WEATHER ADVISORY...INZ001-INZ002-INZ010-INZ011-INZ019 UNTIL MIDNIGHT SATURDAY. LM...GALE WATCH...LMZ080-LMZ261-LMZ362-LMZ364-LMZ366-LMZ563-LMZ565- LMZ567-LMZ669-LMZ671-LMZ673-LMZ675-LMZ777-LMZ779-LMZ868- LMZ870-LMZ872-LMZ874-LMZ876-LMZ878...3 AM SUNDAY TO 9 PM SUNDAY. && $$
AREA FORECAST DISCUSSION
NWS LINCOLN IL
1142 AM CST THU JAN 19 2012 .DISCUSSION... ISSUED 1023 AM CST THU JAN 19 2012 BAND OF LIGHT SNOW THAT IMPACTED NORTH-CENTRAL ILLINOIS EARLY THIS MORNING IS QUICKLY PUSHING OFF TO THE EAST. 16Z RADAR IMAGERY/SURFACE OBS SHOW LIGHT SNOW PERSISTING ACROSS ONLY THE FAR NORTHERN KILX CWA...WITH MOSTLY CLOUDY AND DRY CONDITIONS ELSEWHERE. BASED ON TRENDS...HAVE UPDATED THE FORECAST TO REMOVE MENTION OF SNOW EVERYWHERE EXCEPT ALONG/NORTHEAST OF THE I-74 CORRIDOR WHERE IT WILL CONTINUE FOR THE NEXT COUPLE OF HOURS. NOT EXPECTING MUCH ADDITIONAL ACCUMULATION...WITH STORM TOTAL AMOUNTS OF AROUND 1 INCH NORTH OF A GALESBURG TO LEXINGTON LINE. ONCE THE SNOW ENDS...A MOSTLY CLOUDY AND COLD AFTERNOON WILL TAKE SHAPE ACROSS THE ENTIRE AREA. TEMPERATURES WILL RISE A FEW MORE DEGREES INTO THE MIDDLE TO UPPER 30S ALONG/SOUTH OF I-70 BY MIDDAY...THEN READINGS WILL DROP INTO THE 20S THIS AFTERNOON. ELSEWHERE...TEMPS WILL REMAIN NEARLY STEADY OR SLOWLY FALL INTO THE TEENS. && .AVIATION... ISSUED 1142 AM CST THU JAN 19 2012 LIGHT SNOW AND LOW CEILINGS AROUND 2500FT WILL CONTINUE TO IMPACT BOTH KPIA AND KBMI UNTIL 19/20Z...BEFORE THE PRECIP GRADUALLY SHIFTS OFF TO THE EAST. MEANWHILE...A MID-LEVEL CLOUD DECK WILL PREVAIL AT THE REMAINING TERMINALS. SATELLITE IMAGERY SHOWS CLOUD COVER CLEARING OUT ACROSS CENTRAL IOWA...AND BASED ON TIMING TOOLS AND NAM RH PROFILES...IT APPEARS SKIES WILL CLEAR FROM WEST TO EAST ACROSS CENTRAL ILLINOIS BETWEEN 21Z AND 23Z. MOSTLY CLEAR SKIES WILL THEN PREVAIL THROUGH THE EVENING...BEFORE CLOUDS ONCE AGAIN BEGIN TO INCREASE LATE TONIGHT INTO FRIDAY MORNING. FORECAST SOUNDINGS AND TIME-HEIGHT CROSS-SECTIONS SUGGEST CEILINGS LOWERING TO AROUND 1500FT BETWEEN 15Z AND 17Z. SINCE SOUNDINGS DO NOT FULLY SATURATE AND LIFT REMAINS WEAK...THINK ANY LIGHT PRECIP WILL HOLD OFF UNTIL FRIDAY AFTERNOON. WINDS WILL INITIALLY BE FROM THE N/NW AT 10 TO 15KT TODAY...THEN WILL VEER TO EASTERLY AT AROUND 10KT BY FRIDAY MORNING. BARNES && .PREV DISCUSSION... ISSUED 245 AM CST THU JAN 19 2012 SHARP ARCTIC COLD FRONT IS ABOUT TO MOVE INTO THE NORTHWEST TIP OF THE CWA AT 08Z...OVERALL EXTENDING FROM EAST CENTRAL WISCONSIN TO AROUND KANSAS CITY. TEMPERATURES QUICKLY DROP OFF INTO THE SINGLE DIGITS AS CLOSE AS CENTRAL IOWA. AREA OF LIGHT SNOW SO FAR HAS MAINLY BEEN BEHIND THE FRONT. UPSTAIRS...VERY TIGHT UPPER FLOW CONTINUES...WITH EVENING UPPER AIR ANALYSIS SHOWING A SCREAMING 150+ KNOT JET AT 300 MB FROM AROUND SEATTLE SOUTHEAST INTO MISSOURI. MAIN FORECAST CHALLENGE WITH THIS PACKAGE IS WITH PRECIPITATION TYPES FRIDAY AND FRIDAY NIGHT. THE EFFECTS OF THE CURRENT SYSTEM ARE A SECONDARY CONCERN. SHORT TERM...TODAY THROUGH FRIDAY NIGHT... LATEST HRRR MODEL SWEEPS THE FRONT ACROSS THE CWA THIS MORNING... LINGERING THROUGH MIDDAY ACROSS THE FAR SOUTHEAST. BEST LIFT WITH THIS FRONT IS STILL EXPECTED OVER THE NORTHEAST THIRD OF THE CWA...WITH 1-2 INCHES OF SNOW EXPECTED NORTH OF A BLOOMINGTON TO DANVILLE LINE THROUGH EARLY AFTERNOON. SHARP SOUTHERN CUTOFF TO THE SNOW IS EXPECTED...AND WENT WITH ONLY SLIGHT CHANCES SOUTH OF A JACKSONVILLE TO TERRE HAUTE LINE. ONLY THE SOUTHEAST CWA IS EXPECTED TO SEE TEMPERATURES RISE ABOVE FREEZING...WITH MOST OF THE FORECAST AREA SEEING FALLING DAYTIME TEMPERATURES. THE FRIDAY STORM SYSTEM CONTINUES TO HAVE SEPARATE CONCERNS...ONE WITH THE SNOW ACROSS THE NORTH IN THE STRONGER LIFT AND BAROCLINIC ZONE...AND THE POTENTIAL FOR MIXED PRECIPITATION FURTHER SOUTH CLOSER TO THE SURFACE FEATURES. SNOW-WISE...BEST LIFT STILL EXPECTED JUST TO OUR NORTH ACROSS NORTHERN ILLINOIS...BUT 2-3 INCHES IS LIKELY AS FAR SOUTH AS GALESBURG AND PEORIA FRIDAY INTO FRIDAY EVENING. FURTHER SOUTH...FORECAST SOUNDINGS SHOWING A WEDGE OF WARM AIR AROUND 900 MB MOVING IN LATER FRIDAY AFTERNOON AND ESPECIALLY DURING THE EVENING. THE NAM IS MOST PRONOUNCED WITH THIS AROUND CHAMPAIGN AND MATTOON...WHILE THE GFS IS FURTHER SOUTH TOWARD LAWRENCEVILLE AND THE LOCAL WRF IN BETWEEN. EVAPORATIVE COOLING WOULD FAVOR MORE OF A SLEET/SNOW MIXTURE INITIALLY...THEN SOME FREEZING RAIN AND SLEET IN THE EVENING BEFORE SWITCHING OVER TO SNOW LATE TONIGHT. WILL INCLUDE SOME LOW ICE ACCUMULATIONS IN AREAS MAINLY BETWEEN I-72 AND I-70...WITH LOCATIONS FROM MATTOON TO PARIS WITH THE HIGHEST AMOUNTS OF AROUND 0.05 INCH OR SO. MAY NEED TO CONSIDER WINTER WEATHER ADVISORIES IN SOME PARTS OF THE CWA...BUT ENOUGH MODEL VARIABILITY EXISTS TO PRECLUDE ISSUING ONE AT THIS TIME. LONG TERM...SATURDAY THROUGH WEDNESDAY... PRECIPITATION TO BE OUT OF THE AREA BEFORE SUNRISE SATURDAY...WITH HIGH PRESSURE RESULTING IN DRY WEATHER. FOCUS IN THE LONGER TERM SHIFTS TO A DIGGING SHORTWAVE WHICH WILL CROSS THE MIDDLE OF THE NATION SUNDAY NIGHT AND MONDAY. FOLLOWED THE SLOWER ECMWF/CANADIAN SOLUTIONS...WHICH FAVOR RAIN FOR THE MOST PART AND A CHANGEOVER TO SNOW AS THE PRECIPITATION ENDS SUNDAY NIGHT. MODEL SOLUTIONS ARE CLOSER TO EACH OTHER ON THE NEXT WAVE WHICH CROSSES MIDWEEK...WITH THE NEXT SHOT OF PRECIPITATION. ASIDE FROM THE COLD START TO THE WEEKEND...TEMPERATURES MUCH OF THIS PERIOD WILL BE SEVERAL DEGREES ABOVE NORMAL. GEELHART && .ILX WATCHES/WARNINGS/ADVISORIES... NONE. && $$
AREA FORECAST DISCUSSION
NWS LINCOLN IL
1023 AM CST THU JAN 19 2012 .DISCUSSION... ISSUED 1023 AM CST THU JAN 19 2012 BAND OF LIGHT SNOW THAT IMPACTED NORTH-CENTRAL ILLINOIS EARLY THIS MORNING IS QUICKLY PUSHING OFF TO THE EAST. 16Z RADAR IMAGERY/SURFACE OBS SHOW LIGHT SNOW PERSISTING ACROSS ONLY THE FAR NORTHERN KILX CWA...WITH MOSTLY CLOUDY AND DRY CONDITIONS ELSEWHERE. BASED ON TRENDS...HAVE UPDATED THE FORECAST TO REMOVE MENTION OF SNOW EVERYWHERE EXCEPT ALONG/NORTHEAST OF THE I-74 CORRIDOR WHERE IT WILL CONTINUE FOR THE NEXT COUPLE OF HOURS. NOT EXPECTING MUCH ADDITIONAL ACCUMULATION...WITH STORM TOTAL AMOUNTS OF AROUND 1 INCH NORTH OF A GALESBURG TO LEXINGTON LINE. ONCE THE SNOW ENDS...A MOSTLY CLOUDY AND COLD AFTERNOON WILL TAKE SHAPE ACROSS THE ENTIRE AREA. TEMPERATURES WILL RISE A FEW MORE DEGREES INTO THE MIDDLE TO UPPER 30S ALONG/SOUTH OF I-70 BY MIDDAY...THEN READINGS WILL DROP INTO THE 20S THIS AFTERNOON. ELSEWHERE...TEMPS WILL REMAIN NEARLY STEADY OR SLOWLY FALL INTO THE TEENS. BARNES && .AVIATION... ISSUED 543 AM CST THU JAN 19 2012 CONDITIONS WILL BE PRIMARILY VFR AT ALL TAF SITES THROUGH THE PERIOD. A QUICK MOVING WINTER SYSTEM WILL BRING TEMPO SNOW/MVFR CIGS/VIS TO PIA/BMI/CMI THIS MORNING THROUGH ABOUT NOON...WHILE SPI/DEC JUST WILL HAVE VCSH AND SCATTERED AT 2.5KFT. ONCE SYSTEM PASSES CLOUDS HEIGHTS WILL RISE AGAIN AND WILL BE LEFT WITH JUST CIRRUS CLOUDS FROM THIS AFTERNOON THROUGH TONIGHT. WINDS WILL BE SOUTHWEST AHEAD OF THE FRONT BUT QUICKLY SWITCH TO NORTHWEST BEHIND THE FRONT. EXPECT NORTHERLY WINDS THIS AFTERNOON THROUGH THIS EVENING...BECOMING NORTHEAST OVERNIGHT. TIGHT TEMP GRADIENT BEHIND FRONT WILL BRING SOME STRONGER WINDS...BUT GRADIENT WEAKENS A FEW HOURS BEHIND THE FRONT SO WINDS WILL DECREASE REST OF THE PERIOD. AUTEN && .PREV DISCUSSION... ISSUED 245 AM CST THU JAN 19 2012 SHARP ARCTIC COLD FRONT IS ABOUT TO MOVE INTO THE NORTHWEST TIP OF THE CWA AT 08Z...OVERALL EXTENDING FROM EAST CENTRAL WISCONSIN TO AROUND KANSAS CITY. TEMPERATURES QUICKLY DROP OFF INTO THE SINGLE DIGITS AS CLOSE AS CENTRAL IOWA. AREA OF LIGHT SNOW SO FAR HAS MAINLY BEEN BEHIND THE FRONT. UPSTAIRS...VERY TIGHT UPPER FLOW CONTINUES...WITH EVENING UPPER AIR ANALYSIS SHOWING A SCREAMING 150+ KNOT JET AT 300 MB FROM AROUND SEATTLE SOUTHEAST INTO MISSOURI. MAIN FORECAST CHALLENGE WITH THIS PACKAGE IS WITH PRECIPITATION TYPES FRIDAY AND FRIDAY NIGHT. THE EFFECTS OF THE CURRENT SYSTEM ARE A SECONDARY CONCERN. SHORT TERM...TODAY THROUGH FRIDAY NIGHT... LATEST HRRR MODEL SWEEPS THE FRONT ACROSS THE CWA THIS MORNING... LINGERING THROUGH MIDDAY ACROSS THE FAR SOUTHEAST. BEST LIFT WITH THIS FRONT IS STILL EXPECTED OVER THE NORTHEAST THIRD OF THE CWA...WITH 1-2 INCHES OF SNOW EXPECTED NORTH OF A BLOOMINGTON TO DANVILLE LINE THROUGH EARLY AFTERNOON. SHARP SOUTHERN CUTOFF TO THE SNOW IS EXPECTED...AND WENT WITH ONLY SLIGHT CHANCES SOUTH OF A JACKSONVILLE TO TERRE HAUTE LINE. ONLY THE SOUTHEAST CWA IS EXPECTED TO SEE TEMPERATURES RISE ABOVE FREEZING...WITH MOST OF THE FORECAST AREA SEEING FALLING DAYTIME TEMPERATURES. THE FRIDAY STORM SYSTEM CONTINUES TO HAVE SEPARATE CONCERNS...ONE WITH THE SNOW ACROSS THE NORTH IN THE STRONGER LIFT AND BAROCLINIC ZONE...AND THE POTENTIAL FOR MIXED PRECIPITATION FURTHER SOUTH CLOSER TO THE SURFACE FEATURES. SNOW-WISE...BEST LIFT STILL EXPECTED JUST TO OUR NORTH ACROSS NORTHERN ILLINOIS...BUT 2-3 INCHES IS LIKELY AS FAR SOUTH AS GALESBURG AND PEORIA FRIDAY INTO FRIDAY EVENING. FURTHER SOUTH...FORECAST SOUNDINGS SHOWING A WEDGE OF WARM AIR AROUND 900 MB MOVING IN LATER FRIDAY AFTERNOON AND ESPECIALLY DURING THE EVENING. THE NAM IS MOST PRONOUNCED WITH THIS AROUND CHAMPAIGN AND MATTOON...WHILE THE GFS IS FURTHER SOUTH TOWARD LAWRENCEVILLE AND THE LOCAL WRF IN BETWEEN. EVAPORATIVE COOLING WOULD FAVOR MORE OF A SLEET/SNOW MIXTURE INITIALLY...THEN SOME FREEZING RAIN AND SLEET IN THE EVENING BEFORE SWITCHING OVER TO SNOW LATE TONIGHT. WILL INCLUDE SOME LOW ICE ACCUMULATIONS IN AREAS MAINLY BETWEEN I-72 AND I-70...WITH LOCATIONS FROM MATTOON TO PARIS WITH THE HIGHEST AMOUNTS OF AROUND 0.05 INCH OR SO. MAY NEED TO CONSIDER WINTER WEATHER ADVISORIES IN SOME PARTS OF THE CWA...BUT ENOUGH MODEL VARIABILITY EXISTS TO PRECLUDE ISSUING ONE AT THIS TIME. LONG TERM...SATURDAY THROUGH WEDNESDAY... PRECIPITATION TO BE OUT OF THE AREA BEFORE SUNRISE SATURDAY...WITH HIGH PRESSURE RESULTING IN DRY WEATHER. FOCUS IN THE LONGER TERM SHIFTS TO A DIGGING SHORTWAVE WHICH WILL CROSS THE MIDDLE OF THE NATION SUNDAY NIGHT AND MONDAY. FOLLOWED THE SLOWER ECMWF/CANADIAN SOLUTIONS...WHICH FAVOR RAIN FOR THE MOST PART AND A CHANGEOVER TO SNOW AS THE PRECIPITATION ENDS SUNDAY NIGHT. MODEL SOLUTIONS ARE CLOSER TO EACH OTHER ON THE NEXT WAVE WHICH CROSSES MIDWEEK...WITH THE NEXT SHOT OF PRECIPITATION. ASIDE FROM THE COLD START TO THE WEEKEND...TEMPERATURES MUCH OF THIS PERIOD WILL BE SEVERAL DEGREES ABOVE NORMAL. GEELHART && .ILX WATCHES/WARNINGS/ADVISORIES... NONE. && $$
AREA FORECAST DISCUSSION
NWS LINCOLN IL
543 AM CST THU JAN 19 2012 .DISCUSSION... ISSUED 245 AM CST THU JAN 19 2012 SHARP ARCTIC COLD FRONT IS ABOUT TO MOVE INTO THE NORTHWEST TIP OF THE CWA AT 08Z...OVERALL EXTENDING FROM EAST CENTRAL WISCONSIN TO AROUND KANSAS CITY. TEMPERATURES QUICKLY DROP OFF INTO THE SINGLE DIGITS AS CLOSE AS CENTRAL IOWA. AREA OF LIGHT SNOW SO FAR HAS MAINLY BEEN BEHIND THE FRONT. UPSTAIRS...VERY TIGHT UPPER FLOW CONTINUES...WITH EVENING UPPER AIR ANALYSIS SHOWING A SCREAMING 150+ KNOT JET AT 300 MB FROM AROUND SEATTLE SOUTHEAST INTO MISSOURI. MAIN FORECAST CHALLENGE WITH THIS PACKAGE IS WITH PRECIPITATION TYPES FRIDAY AND FRIDAY NIGHT. THE EFFECTS OF THE CURRENT SYSTEM ARE A SECONDARY CONCERN. SHORT TERM...TODAY THROUGH FRIDAY NIGHT... LATEST HRRR MODEL SWEEPS THE FRONT ACROSS THE CWA THIS MORNING... LINGERING THROUGH MIDDAY ACROSS THE FAR SOUTHEAST. BEST LIFT WITH THIS FRONT IS STILL EXPECTED OVER THE NORTHEAST THIRD OF THE CWA...WITH 1-2 INCHES OF SNOW EXPECTED NORTH OF A BLOOMINGTON TO DANVILLE LINE THROUGH EARLY AFTERNOON. SHARP SOUTHERN CUTOFF TO THE SNOW IS EXPECTED...AND WENT WITH ONLY SLIGHT CHANCES SOUTH OF A JACKSONVILLE TO TERRE HAUTE LINE. ONLY THE SOUTHEAST CWA IS EXPECTED TO SEE TEMPERATURES RISE ABOVE FREEZING...WITH MOST OF THE FORECAST AREA SEEING FALLING DAYTIME TEMPERATURES. THE FRIDAY STORM SYSTEM CONTINUES TO HAVE SEPARATE CONCERNS...ONE WITH THE SNOW ACROSS THE NORTH IN THE STRONGER LIFT AND BAROCLINIC ZONE...AND THE POTENTIAL FOR MIXED PRECIPITATION FURTHER SOUTH CLOSER TO THE SURFACE FEATURES. SNOW-WISE...BEST LIFT STILL EXPECTED JUST TO OUR NORTH ACROSS NORTHERN ILLINOIS...BUT 2-3 INCHES IS LIKELY AS FAR SOUTH AS GALESBURG AND PEORIA FRIDAY INTO FRIDAY EVENING. FURTHER SOUTH...FORECAST SOUNDINGS SHOWING A WEDGE OF WARM AIR AROUND 900 MB MOVING IN LATER FRIDAY AFTERNOON AND ESPECIALLY DURING THE EVENING. THE NAM IS MOST PRONOUNCED WITH THIS AROUND CHAMPAIGN AND MATTOON...WHILE THE GFS IS FURTHER SOUTH TOWARD LAWRENCEVILLE AND THE LOCAL WRF IN BETWEEN. EVAPORATIVE COOLING WOULD FAVOR MORE OF A SLEET/SNOW MIXTURE INITIALLY...THEN SOME FREEZING RAIN AND SLEET IN THE EVENING BEFORE SWITCHING OVER TO SNOW LATE TONIGHT. WILL INCLUDE SOME LOW ICE ACCUMULATIONS IN AREAS MAINLY BETWEEN I-72 AND I-70...WITH LOCATIONS FROM MATTOON TO PARIS WITH THE HIGHEST AMOUNTS OF AROUND 0.05 INCH OR SO. MAY NEED TO CONSIDER WINTER WEATHER ADVISORIES IN SOME PARTS OF THE CWA...BUT ENOUGH MODEL VARIABILITY EXISTS TO PRECLUDE ISSUING ONE AT THIS TIME. LONG TERM...SATURDAY THROUGH WEDNESDAY... PRECIPITATION TO BE OUT OF THE AREA BEFORE SUNRISE SATURDAY...WITH HIGH PRESSURE RESULTING IN DRY WEATHER. FOCUS IN THE LONGER TERM SHIFTS TO A DIGGING SHORTWAVE WHICH WILL CROSS THE MIDDLE OF THE NATION SUNDAY NIGHT AND MONDAY. FOLLOWED THE SLOWER ECMWF/CANADIAN SOLUTIONS...WHICH FAVOR RAIN FOR THE MOST PART AND A CHANGEOVER TO SNOW AS THE PRECIPITATION ENDS SUNDAY NIGHT. MODEL SOLUTIONS ARE CLOSER TO EACH OTHER ON THE NEXT WAVE WHICH CROSSES MIDWEEK...WITH THE NEXT SHOT OF PRECIPITATION. ASIDE FROM THE COLD START TO THE WEEKEND...TEMPERATURES MUCH OF THIS PERIOD WILL BE SEVERAL DEGREES ABOVE NORMAL. GEELHART && .AVIATION... ISSUED 543 AM CST THU JAN 19 2012 CONDITIONS WILL BE PRIMARILY VFR AT ALL TAF SITES THROUGH THE PERIOD. A QUICK MOVING WINTER SYSTEM WILL BRING TEMPO SNOW/MVFR CIGS/VIS TO PIA/BMI/CMI THIS MORNING THROUGH ABOUT NOON...WHILE SPI/DEC JUST WILL HAVE VCSH AND SCATTERED AT 2.5KFT. ONCE SYSTEM PASSES CLOUDS HEIGHTS WILL RISE AGAIN AND WILL BE LEFT WITH JUST CIRRUS CLOUDS FROM THIS AFTERNOON THROUGH TONIGHT. WINDS WILL BE SOUTHWEST AHEAD OF THE FRONT BUT QUICKLY SWITCH TO NORTHWEST BEHIND THE FRONT. EXPECT NORTHERLY WINDS THIS AFTERNOON THROUGH THIS EVENING...BECOMING NORTHEAST OVERNIGHT. TIGHT TEMP GRADIENT BEHIND FRONT WILL BRING SOME STRONGER WINDS...BUT GRADIENT WEAKENS A FEW HOURS BEHIND THE FRONT SO WINDS WILL DECREASE REST OF THE PERIOD. AUTEN && .ILX WATCHES/WARNINGS/ADVISORIES... NONE. && $$
AREA FORECAST DISCUSSION
NWS LINCOLN IL
248 AM CST THU JAN 19 2012 .DISCUSSION... ISSUED 245 AM CST THU JAN 19 2012 SHARP ARCTIC COLD FRONT IS ABOUT TO MOVE INTO THE NORTHWEST TIP OF THE CWA AT 08Z...OVERALL EXTENDING FROM EAST CENTRAL WISCONSIN TO AROUND KANSAS CITY. TEMPERATURES QUICKLY DROP OFF INTO THE SINGLE DIGITS AS CLOSE AS CENTRAL IOWA. AREA OF LIGHT SNOW SO FAR HAS MAINLY BEEN BEHIND THE FRONT. UPSTAIRS...VERY TIGHT UPPER FLOW CONTINUES...WITH EVENING UPPER AIR ANALYSIS SHOWING A SCREAMING 150+ KNOT JET AT 300 MB FROM AROUND SEATTLE SOUTHEAST INTO MISSOURI. MAIN FORECAST CHALLENGE WITH THIS PACKAGE IS WITH PRECIPITATION TYPES FRIDAY AND FRIDAY NIGHT. THE EFFECTS OF THE CURRENT SYSTEM ARE A SECONDARY CONCERN. SHORT TERM...TODAY THROUGH FRIDAY NIGHT... LATEST HRRR MODEL SWEEPS THE FRONT ACROSS THE CWA THIS MORNING... LINGERING THROUGH MIDDAY ACROSS THE FAR SOUTHEAST. BEST LIFT WITH THIS FRONT IS STILL EXPECTED OVER THE NORTHEAST THIRD OF THE CWA...WITH 1-2 INCHES OF SNOW EXPECTED NORTH OF A BLOOMINGTON TO DANVILLE LINE THROUGH EARLY AFTERNOON. SHARP SOUTHERN CUTOFF TO THE SNOW IS EXPECTED...AND WENT WITH ONLY SLIGHT CHANCES SOUTH OF A JACKSONVILLE TO TERRE HAUTE LINE. ONLY THE SOUTHEAST CWA IS EXPECTED TO SEE TEMPERATURES RISE ABOVE FREEZING...WITH MOST OF THE FORECAST AREA SEEING FALLING DAYTIME TEMPERATURES. THE FRIDAY STORM SYSTEM CONTINUES TO HAVE SEPARATE CONCERNS...ONE WITH THE SNOW ACROSS THE NORTH IN THE STRONGER LIFT AND BAROCLINIC ZONE...AND THE POTENTIAL FOR MIXED PRECIPITATION FURTHER SOUTH CLOSER TO THE SURFACE FEATURES. SNOW-WISE...BEST LIFT STILL EXPECTED JUST TO OUR NORTH ACROSS NORTHERN ILLINOIS...BUT 2-3 INCHES IS LIKELY AS FAR SOUTH AS GALESBURG AND PEORIA FRIDAY INTO FRIDAY EVENING. FURTHER SOUTH...FORECAST SOUNDINGS SHOWING A WEDGE OF WARM AIR AROUND 900 MB MOVING IN LATER FRIDAY AFTERNOON AND ESPECIALLY DURING THE EVENING. THE NAM IS MOST PRONOUNCED WITH THIS AROUND CHAMPAIGN AND MATTOON...WHILE THE GFS IS FURTHER SOUTH TOWARD LAWRENCEVILLE AND THE LOCAL WRF IN BETWEEN. EVAPORATIVE COOLING WOULD FAVOR MORE OF A SLEET/SNOW MIXTURE INITIALLY...THEN SOME FREEZING RAIN AND SLEET IN THE EVENING BEFORE SWITCHING OVER TO SNOW LATE TONIGHT. WILL INCLUDE SOME LOW ICE ACCUMULATIONS IN AREAS MAINLY BETWEEN I-72 AND I-70...WITH LOCATIONS FROM MATTOON TO PARIS WITH THE HIGHEST AMOUNTS OF AROUND 0.05 INCH OR SO. MAY NEED TO CONSIDER WINTER WEATHER ADVISORIES IN SOME PARTS OF THE CWA...BUT ENOUGH MODEL VARIABILITY EXISTS TO PRECLUDE ISSUING ONE AT THIS TIME. LONG TERM...SATURDAY THROUGH WEDNESDAY... PRECIPITATION TO BE OUT OF THE AREA BEFORE SUNRISE SATURDAY...WITH HIGH PRESSURE RESULTING IN DRY WEATHER. FOCUS IN THE LONGER TERM SHIFTS TO A DIGGING SHORTWAVE WHICH WILL CROSS THE MIDDLE OF THE NATION SUNDAY NIGHT AND MONDAY. FOLLOWED THE SLOWER ECMWF/CANADIAN SOLUTIONS...WHICH FAVOR RAIN FOR THE MOST PART AND A CHANGEOVER TO SNOW AS THE PRECIPITATION ENDS SUNDAY NIGHT. MODEL SOLUTIONS ARE CLOSER TO EACH OTHER ON THE NEXT WAVE WHICH CROSSES MIDWEEK...WITH THE NEXT SHOT OF PRECIPITATION. ASIDE FROM THE COLD START TO THE WEEKEND...TEMPERATURES MUCH OF THIS PERIOD WILL BE SEVERAL DEGREES ABOVE NORMAL. GEELHART && .AVIATION... ISSUED 1115 PM CST WED JAN 18 2012 TIMING OF COLD FRONT...LIGHT SNOW AND POSSIBLY MVFR CIGS ACROSS THE TAF SITES THE MAIN FORECAST CONCERN THIS PERIOD. COLD FRONT HAS PUSHED INTO EAST CENTRAL IOWA...A BIT QUICKER THAN EARLIER THOUGHT...AND SHOULD NOW APPROACH THE ILLINOIS RIVER VALLEY BETWEEN 09Z AND 11Z. HAVE SEEN AN INCREASE IN LIGHT SNOW OVER THE PAST SEVERAL HOURS OVER PARTS OF NORTHEAST IOWA WITH THE IR SATELLITE LOOP SHOWING AN INCREASE IN COVERAGE OF COLDER CLOUD TOPS ASSOCIATED WITH THE NEXT UPPER LEVEL WAVE AND STRONG JET MAX TO OUR WEST. IT STILL APPEARS MOST OF THE LOWER CIGS AND ANY SNOW WILL BE BEHIND THE COLD FRONT FOR ABOUT A 4-6 HOUR PERIOD STARTING THURS MORNING WITH MOST OF THE LOWER CIGS AND SNOW TO OUR EAST BY 20Z...WITH VFR CONDITIONS PREVAILING INTO THURSDAY NIGHT. ACCUMULATIONS STILL LOOK TO BE AROUND AN INCH NORTH OF A SPI TO CMI LINE TOMORROW MORNING. SFC WINDS WILL CONTINUE FROM THE SOUTH AND SOUTHWEST OVERNIGHT AND SWITCH INTO THE NORTHWEST AFTER FROPA AROUND 10Z AT PIA...BTWN 11Z AND 12Z AT BMI AND SPI...WITH THE FRONT TO THE EAST OF CMI BY 15Z. SMITH && .ILX WATCHES/WARNINGS/ADVISORIES... NONE. && $$
AREA FORECAST DISCUSSION
NWS NORTHERN INDIANA
646 PM EST FRI JAN 20 2012 .AVIATION... RADAR TRENDS...OBSERVATIONS AND HIRES MODEL GUIDANCE USED FOR AVIATION FORECASTS WITH FOCUS ON NEXT SIX HOURS. KSBN WILL REMAIN IN AREA OF MODERATE TO HEAVY SNOW WITH VIS EXPECTED TO REMAIN AT ONE HALF MILE WITH DROPS TO ONE QUARTER MILE FOR NEXT TWO TO FOUR HOURS. HEAVIER SNOW BEGINNING TO DIMINISH NEAR AND JUST WEST OF CHICAGO AREA SO SHOULD SEE SLOW IMPROVEMENT AFTER 03Z THEN RAPID IMPROVEMENT AFTER 06Z WITH DRIER AIR MOVING IN. RADAR SHOWING DRY SLOT PUSHING NORTH TOWARD KFWA AND IT MAY JUST REACH AIRPORT BRIEFLY BEFORE HIGHER RETURNS TO WEST ROTATE BACK IN. FOR NOW HAVE KEPT THE AIRPORT SOCKED IN GIVEN SHORT DURATION OF ANY POSSIBLE BREAK THERE. VIS MAY BRIEFLY DROP BELOW ONE QUARTER MILE BUT FOR NOW HAVE STAYED WITH RESTRICTIONS AROUND ONE HALF AS THAT LOOKS MOSTLY LIKELY WITH LOWER VIS TO THE NORTH OF AIRPORT. WILL MONITOR THOUGH AS SOME HIGHER RETURNS DEVELOPING WEST OF AIRPORT. && .UPDATE... SNOW EVENT EVOLVING AS EXPECTED SO FAR. UPSTREAM REPORTS IN NORTHERN IL INDICATE EXPECTED POTENTIAL FOR SOME AMOUNTS NEAR OR JUST ABOVE 6 INCHES. CURRENT ADVISORY HAS THIS WELL IN HAND WITH WORDING SO CURRENTLY NO PLANS TO UPGRADE HEADLINES UNLESS WE START GETTING WIDESPREAD REPORTS IN EXCESS OF 6 TO 7 INCHES LATER THIS EVENING WITH ADDITIONAL SNOWFALL EXPECTED. MOST REPORTS SO FAR IN THE 1 TO 3 INCH RANGE WITH A FEW EXCEPTIONS. VISIBILITIES BEGINNING TO RISE SLOWLY NEAR AND WEST OF CHICAGO SO EXPECT OUR WESTERN AREAS TO SEE THIS MODERATE TO BRIEFLY HEAVY SNOW FOR A FEW MORE HOURS BEFORE SNOWFALL RATES GRADUALLY DECREASE THERE WITH PROGRESSION EAST THROUGH THE LATE EVENING AND OVERNIGHT HOURS. HIGH RES GUIDANCE ALSO SHOWING THIS WITH HRRR LOOKING VERY GOOD SO FAR. && .SHORT TERM...TONIGHT THROUGH SATURDAY NIGHT MAIN FORECAST FOCUS WILL CONTINUE TO CENTER ON SIGNIFICANT SNOW ACCUMULATIONS TONIGHT. A WINTER WEATHER ADVISORY WILL REMAIN IN EFFECT FOR THE ENTIRE FORECAST AREA THROUGH 12Z SATURDAY. A ZONE OF STRONG ISENTROPIC UPGLIDE PER RUC/GFS 290K SFC WILL CONTINUE TO LIFT NORTHEAST ACROSS NORTHERN PORTIONS OF THE FORECAST AREA. SEVERAL REPORTS NOW OF 1/2 TO 1/4 MILE VSBYS ACROSS NORTHERN ILLINOIS AND STRONGEST ISENTROPIC ASCENT SHOULD SHIFT EASTWARD ACROSS NORTHERN INDIANA/SOUTHERN LOWER MICHIGAN IN THE 22Z-03Z TIMEFRAME. DURING THIS PERIOD OF STRONGER FORCING...STRONGEST UPWARD VERTICAL MOTION SHOULD BE SOLIDLY ENCOMPASSED IN FAVORABLE DENDRITIC GROWTH ZONE. THUS...SHOULD SEE A PERIOD EARLY THIS EVENING WHERE SNOW TO LIQUID RATIOS INCREASE SHARPLY FOR A TIME. ISENTROPIC PROGS HAVE ALSO SUGGESTED PERHAPS A SLIGHT WEAKENING OF THE ISENTROPIC LIFT THIS EVENING AS VORT MAX SKIRTING ACROSS SOUTHERN WISCONSIN THIS AFTERNOON BECOMES MORE SHEARED ACROSS THE SOUTHERN LAKES. NONETHELESS...A 2 TO 4 PERIOD OF SNOWFALL RATES AROUND AN INCH PER HOUR APPEARS TO BE POSSIBLE LATE THIS AFTERNOON/EARLY THIS EVENING FOR AREAS ESPECIALLY ALONG AND NORTH OF THE ROUTE 30 CORRIDOR. ACCUMULATIONS WILL BE IN SOMEWHAT MORE QUESTION ACROSS THE SOUTH AS THIS BAND SHOULD PROVIDE GREAT IMPACTS ACROSS THE NORTHERN HALF. WATER VAPOR IMAGERY CONTINUES TO INDICATE A STRONGER VORT MAX DROPPING INTO THE CENTRAL PLAINS THAT WILL BEGIN TO SHIFT EASTWARD INTO THE MID MS RVR VALLEY LATER THIS EVENING. SHOULD START TO SEE A MORE FRONTALLY FORCED AREA OF SNOW DEVELOP EXTENDING SOUTHWEST FROM THIS INITIALLY WEST TO EAST ORIENTED BAND THAT WILL AFFECT CENTRAL/SOUTHERN AREAS LATE THIS EVENING. STILL EXPECTING STORM TOTAL SNOWFALL AMOUNTS IN THE 4 TO 7 RANGE CENTRAL AND NORTH...WITH AMOUNTS IN THE 2 TO 4 RANGE FAR SOUTH. GFS/RUC VERTICAL CROSS SECTIONS ALSO INDICATE INCREASING INSTABILITY ALOFT (NEGATIVE EPV) LIFTING ACROSS EASTERN SECTIONS OF THE AREA LATE THIS EVENING AS SOUTHWESTERLY FLOW STRENGTHENS IN ADVANCE OF THIS SECONDARY SHORT WAVE. THIS INCREASE IN INSTABILITY ALOFT SHOULD CORRESPOND TO THIS SECONDARY MID LEVEL FORCING MAX WITH THIS SHORT WAVE...SO HAVE KEPT AMOUNTS MORE SOLIDLY IN THE ADVISORY RANGE IN THE FAR SOUTHEAST...WITH SLIGHTLY LESSER TOTALS IN THE SOUTHWEST. CURRENTLY HAVE DRAWN UP TOTAL ACCUMULATIONS JUST BELOW ADVISORY CRITERIA ACROSS THE SOUTHWEST BUT DUE TO COMPLICATING MESOSCALE FORCING MECHANISMS MENTIONED...WILL MAINTAIN ALL HEADLINES AT THIS TIME. CONDITIONS TO IMPROVE FROM WEST TO EAST OVERNIGHT WITH THE PASSAGE OF THIS SECONDARY VORT MAX. ORIENTATION OF RIDGE AXIS TO THE WEST SHOULD SUPPORT ANY LAKE EFFECT SNOW SHOWERS WEST OF THE LOCAL FORECAST AREA INTO NORTHWEST INDIANA/NORTHEAST ILLINOIS. SATURDAY SHOULD FEATURE QUIET WEATHER WITH SFC HIGH BEGINNING TO BUILD IN. WEAK LOW LEVEL EASTERLIES AND NEW SNOW COVER SHOULD PROMOTE WEAK MIXING AND HAVE UNDERCUT MOST AVAILABLE GUIDANCE FOR HIGH TEMPS. && .LONG TERM... SUNDAY THROUGH FRIDAY MID LEVEL FLOW TRANSITION STILL ON TRACK IN THE PERIOD GIVEN THE RETURN OF ALASKA TROUGHING...WITH MUCH MILDER PAC ORIGIN DOWNSLOPE FLOW EXPECTED INTO THE REGION BY EARLY NEXT WEEK. A DEEP LONGWAVE TROUGH IS STILL EXPECTED IN THE SUN NIGHT-MON PERIOD...SUPPORTING ROBUST LL FLOW FIELDS WITH SIG THETA-E ADVECTION INTO THE AREA. SPLIT FLOW REGIME WILL FOLLOW WITH STRONG MODEL/ENSEMBLE SUPPORT CONTINUING. FAST PERTURBED WNW FLOW WILL OFFER LOW CONFIDENCE PER DISTURBANCE TIMING IN THE LATE PERIODS GIVEN TYPICAL POOR MODEL PERFORMANCE PER THESE FEATURES. HENCE...NO SIG CHANGE PER PRECIP CHANCE WED-FRI...WITH PREFERENCE TOWARD 24-36 HOUR FORECAST WINDOWS PER PRECIP CHANCES GIVEN INHERENT VARIABILITY PER IMPULSE TIMING. SUN-MON...SIG MID LEVEL TROUGH IS STILL ON TRACK TO DIG INTO THE SW CONUS AND BEGIN TO EJECT TOWARD THE REGION. ECMWF/GEM/UKMET ARE PREFERRED GIVEN THEIR HANDLING OF THE DIGGING MID LEVEL TROUGH WITH NEGATIVE TILT CHARACTERISTICS. CERTAINLY DONT BUY THE NAM/S OUTLIER NORTH BIAS PER THE SFC CYCLONE AND THE GFS/S WILD VARIABILITY PER TROUGH DEPTH/TIMING/AND TRACK. CONTINUED MODEL SUPPORT FOR A STRONG SOUTHERN PERIPHERY UPPER JET STREAK AND NEGATIVE UPPER TROUGH TILT SUGGESTS A WEST BIAS TO THE SFC LOW TRACK WITH SLOWER SYSTEM ARRIVAL AND HAVE CONTINUED THIS IN THE GRIDS. SYSTEM INFLUENCE TO THE LOCAL AREA WILL BEGIN ON SUNDAY...WITH REFLECTED LL SOUTHERLY FLOW INCREASING THROUGH THE SUNDAY DAY PERIOD. LINGERING BAROCLINIC ZONE IN PLACE OVER THE CENTRAL PLAINS WILL INTERACT WITH THE EJECTING MID LEVEL DISTURBANCE TO SUPPORT ROBUST SFC PRESSURE FALLS...SUPPORTING RAPID SFC CYCLOGENESIS. THIS WILL ALLOW SIG LL THETA-E ADV TO ENSUE LATE SUNDAY IN THE REGION WITH SIG SFC LAYER DEWPOINT RISES BY SUNDAY NIGHT. STAUNCH LL FLOW WITH A 60 TO 70 KNOT LLJ PROGGED IN THE ECMWF...WILL BE MORE THAN ENOUGH TO SUPPORT DEEP LAYER THETA-E RISES. SNOWPACK IN PLACE WILL LIKELY SUPPORT A SATURATED BL WITH DRIZZLE AND FOG EXPECTED TO DEVELOP LATE SUNDAY AFTERNOON /AT THE EARLIEST/ INTO THE EVENING...LIKELY PERSISTING THROUGH SUNDAY NIGHT. ECMWF H7-H3 LAYER ANALYSIS CONTINUES TO INDICATE AN INTACT EML WITH STEEP MID LEVEL LAPSE RATES GIVEN STRONG LOW CENTERED WAA. H85 THETA-E APPROACHES 325K BY LATE SUNDAY NIGHT...WITH SW INDICES NEGATIVE...INDICATING A GOOD ENVIRONMENT FOR ELEVATED THUNDERSTORMS. HAVE MAINTAINED A LOW CHANCE THUNDER AT THIS POINT. ALBEIT SMALL...THERE REMAINS A SMALL CONCERN FOR SEVERE WEATHER GIVEN INDICATED H5 JETLET IN EXCESS OF 85 KNOTS...WHICH WOULD BE CAPABLE OF SUPPORTING A QLCS JET DRIVEN THIN LINE. CONCERNS FOR INCREASED FLOODING CONTINUE GIVEN FULL SNOWPACK MELT WITH THE POTENTIAL FOR HEAVY RAIN. IN ADDITION...A SLOWER TROUGH ARRIVAL PER NEGATIVE TROUGH TENDENCIES WOULD SUPPORT HIGHS INTO THE 50S AKIN TO ECMWF PROGS. CAA WILL DOMINATE MONDAY WITH FALLING TEMPS IN THE DAYTIME PERIOD LIKELY. LINGERING LIGHT SNOW SHOWERS WILL BE POSSIBLE. TUE-FRI...FAST WNW PAC ORIGIN FLOW IS EXPECTED INTO THE REGION WITH ROCKIES ENHANCED IMPULSES EXPECTED. STRONGEST PROGGED IMPULSE REMAINS IN THE WED-THUR PERIOD AND HAVE RETAINED POPS THEN...OPTING TO KEEP THE RAIN/SNOW WORDING GIVEN WARM THERMAL FIELDS. HAVE ALSO EXTENDED THIS MENTION INTO FRIDAY MAINLY PER COLLAB WITH SURROUNDING OFFICES...WHICH ALSO FITS THE ACTIVE PATTERN. OTHERWISE...ADJUSTED TEMPS UP SOME...WITH ABOVE NORMAL TEMPS LIKELY ONCE AGAIN. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...WINTER WEATHER ADVISORY UNTIL 7 AM EST /6 AM CST/ SATURDAY FOR INZ003>009-012>018-020-022>027-032>034. MI...WINTER WEATHER ADVISORY UNTIL 7 AM EST SATURDAY FOR MIZ077>081. OH...WINTER WEATHER ADVISORY UNTIL 7 AM EST SATURDAY FOR OHZ001-002- 004-005-015-016-024-025. LM...NONE. && $$ SHORT TERM...MARSILI LONG TERM...JC AVIATION...LASHLEY UPDATE...LASHLEY
AREA FORECAST DISCUSSION
NWS NORTHERN INDIANA
410 PM EST THU JAN 19 2012 .SHORT TERM...TONIGHT THROUGH FRIDAY NIGHT SIGNIFICANT SNOW ACCUMULATIONS FRIDAY/FRIDAY NIGHT WILL BE THE MAIN CONCERN FOR THE SHORT TERM. A WINTER WEATHER ADVISORY WILL BE ISSUED FOR LATE MORNING FRIDAY THROUGH FRIDAY NIGHT FOR APPROXIMATELY NORTHERN TWO THIRDS OF THE FORECAST AREA. ACCUMULATING LIGHT SNOW THIS AFTERNOON HAS SHIFTED WELL SOUTH OF ROUTE 30 LATE THIS AFTERNOON...AND WILL CONTINUE TO SAG SOUTHWARD THROUGH THE REMAINDER OF THE LATE AFTERNOON HOURS AS AXIS OF LOW LEVEL FRONTOGENESIS PUSHES SOUTH OF THE FORECAST AREA. FURTHER TO THE NORTH...LAKE EFFECT SNOW SHOWERS HAVE BEEN INCREASING IN INTENSITY WITH FAIRLY STRONG 850 HPA/LAKE DELTA TEMPS ON THE ORDER OF 20 TO 23 DEGREES. RUC SOUNDINGS SUGGEST A NEARLY ISOTHERMAL LAYER FROM 850 TO 700 HPA WHICH IS LIMITING DEPTH OF THIS LAKE GENERATED INSTABILITY WITH LAKE INDUCED EQUILIBRIUM HEIGHTS ON THE ORDER OF ABOUT 5K FT. ANOTHER NEGATIVE FACTOR POINTING AGAINST SIGNIFICANT LAKE EFFECT SNOW ACCUMULATIONS IS MUCH DRIER MID LEVEL AIR THAT WAS WORKED INTO THE SOUTHERN GREAT LAKES REGION BEHIND THE SYSTEM WHICH BROUGHT THE ACCUMULATING SNOW TODAY. THIS MARGINAL LAKE EFFECT SETUP WILL CONTINUE FOR MUCH OF THE EVENING AND INTO THE OVERNIGHT...AND A FEW LOCATIONS MAY PICK UP A HALF INCH TO AN INCH OF ADDITIONAL ACCUMULATION BEFORE INVERSION HEIGHTS CRASH MORE SUBSTANTIALLY DURING THE OVERNIGHT HOURS. AREAS AWAY FROM LAKE EFFECT CLOUDS/PRECIP SHOULD CLEAR THIS EVENING. A WEAKENING GRADIENT WITH SFC RIDGE AXIS BUILDING IN COMBINED WITH THIS CLEARING SHOULD ALLOW FOR VERY COLD TEMPS TONIGHT INTO THE SINGLE DIGITS ABOVE ZERO. SOME INCREASE IN HIGH CLOUDS IS EXPECTED LATE TONIGHT THAT MAY LEVEL OUT TEMPERATURES AFTER 09Z. ATTENTION WILL THEN TURN TO WHAT WILL BE A VERY FAST MOVING UPPER LEVEL SYSTEM THAT IS APPROACHING THE PACIFIC NORTHWEST COAST AT THIS TIME. LOW LEVEL WINDS WILL BACK SOUTHWESTERLY ON FRIDAY AHEAD OF THIS TROUGH WHICH WILL SET UP A PERIOD OF INTENSE ISENTROPIC UPGLIDE FRIDAY AFTERNOON/EARLY EVENING OVER THE SHALLOW RETREATING ARCTIC AIR MASS. STRONG FRONTOGENETIC FORCING ALSO TO DEVELOP IN THE 850/700 LAYER AS THIS LOW LEVEL FLOW RAMPS UP. 12Z NAM REMAINS A SLIGHTLY SLOWER AND FURTHER NORTH OUTLIER IN REGARDS TO THIS SYSTEM...WITH 09Z SREF GENERALLY LENDING SUPPORT TO THE MORE RUN TO RUN CONSISTENT GFS/ECMWF. GENERALLY UTILIZED A PREDOMINATELY SREF/GFS/ECMWF BLEND FOR THIS FORECAST WITH A MUCH SMALLER WEIGHTING TOWARD NAM. PERIOD OF MOST INTENSE SNOWFALL APPEARS TO BE SHAPING UP IN THE 21Z-03Z TIMEFRAME WITH BEST COLOCATION OF STRONGER SYNOPTIC LIFT WITH FAVORABLE DENDRITIC GROWTH ZONE. MODEL QPF FROM 12Z SUITE OF MODELS STILL TEND TO SUPPORT MAINLY HIGH END ADVISORY LEVEL SNOW ACCUMULATIONS WHEN CONSIDERING EXPECTED SNOW TO LIQUID RATIOS ON THE ORDER OF 15:1 ACROSS THE NORTH. CONCERN WITH THESE TYPE OF INTENSE LOW/MID LEVEL BAROCLINIC ZONES IS FOR AREAS OF ENHANCED BANDING WHICH COULD PUSH SOME AREAS INTO LOW END WARNING ACCUMULATIONS. 12Z GFS MODEL CROSS SECTIONS STILL INDICATE RELATIVELY HIGH STATIC STABILITY ATOP THIS LOW LEVEL FRONTOGENESIS FORCING WHICH MAY TEND TO DISCOURAGE SMALLER SCALE INTENSE BANDING...AND A BROADER RESPONSE IN UPWARD VERTICAL MOTION FIELDS. SYSTEM ALSO WILL BE VERY PROGRESSIVE WITH SOME INDICATIONS OF ISENTROPIC UPGLIDE WEAKENING SLIGHTLY FROM WEST TO EAST INTO NORTHEAST INDIANA BY EVENING. TAKING THE ABOVE FACTORS INTO CONSIDERATION HAVE OPTED TO GO WITH A HIGH END WINTER WEATHER ADVISORY FOR SNOW ACCUMULATIONS OF 3 TO 7 INCHES NORTHERN TWO THIRDS...WITH THE HIGHER ACCUMULATIONS EXPECTED FAR NORTHERN INDIANA/SOUTHERN LOWER MICHIGAN. WINDS NOT EXPECTED TO BE AN OVERLY HUGE CONCERN WITH THIS SYSTEM...BUT A BRIEF PERIOD IN THE 21Z-03Z TIMEFRAME OF 1 TO 2 INCH PER HOUR SNOWFALL RATES APPEARS TO BE A GOOD POSSIBILITY. IN TRENDING MORE TOWARD GFS...HAVE CONFINED MIXED PRECIP MENTION TO A CHANCE OF SLEET ACROSS THE SOUTH BUT THIS WILL NEED TO BE WATCHED IN FUTURE FORECASTS ONCE CONFIDENCE IN LOW LEVEL THERMAL FIELDS INCREASES. SNOW WILL BEGIN TO WANE LATE FRIDAY NIGHT WITH INDICATIONS OF FAR SOUTHEAST GETTING INTO SOME ENHANCED SNOWFALL AS A PIECE OF EASTERN PACIFIC SHORT WAVE DIGS MORE AGGRESSIVELY INTO THE OHIO RIVER VALLEY. && .LONG TERM... SUNDAY THROUGH THURSDAY SIG PATTERN ADJUSTMENT TO OCCUR IN THE LONG TERM PERIOD AS REX BLOCK RIDGING SHIFTS WEST OVER ALASKA...WITH SUBSTANTIAL UPPER LEVEL TROUGHING EXPECTED THERE BY THIS WEEKEND. THIS WILL RESULT IN A SWITCH BACK TO FAST WESTERLY GENERALLY MILD FLOW...WITH EMBEDDED FAST MOVING IMPULSES PROVIDING PERIODIC CHANCES FOR RAIN/SNOW. THIS WILL OCCUR AFTER THE ADVECTION OF A POTENT MID LATITUDE CYCLONE EARLY NEXT WEEK...A SYSTEM WHICH COULD BRING A SUBSTANTIAL AMOUNT OF RAIN/WIND/AND EVEN THUNDERSTORMS TO THE AREA SUNDAY NIGHT INTO MONDAY MORNING. ECMWF/GFS/AND GEFS SOLUTIONS CONTINUE TO REMAIN NEARLY PHASED PER HEIGHT SOLUTIONS IN THE PERIOD...WITH INCREASED FORECAST CONFIDENCE IN THE PERIOD. SAT-MON...FRIDAY SYSTEM WILL BE IN THE PROCESSES OF EXITING THE REGION WITH A LOW CHANCE FOR LINGERING LIGHT SNOW FAR SE SAT AM. WEAK SUBSIDENT REGIME WITH SFC RIDGING WILL SUPPORT GRADUAL EROSION OF LINGERING LOW CLOUDS...WITH WINDS VEERING SE THROUGH THE SAT PERIOD. MEANWHILE...A SIG MID LEVEL TROUGH IS EXPECTED TO DIG INTO THE SW CONUS AND BEGIN TO EJECT TOWARD THE REGION. SYSTEM INFLUENCE TO THE LOCAL AREA WILL BEGIN ON SUNDAY...WITH REFLECTED LL SOUTHERLY FLOW INCREASING THROUGH THE SUNDAY DAY PERIOD. LINGERING BAROCLINIC ZONE IN PLACE OVER THE CENTRAL PLAINS WILL INTERACT WITH THE EJECTING MID LEVEL DISTURBANCE TO SUPPORT ROBUST SFC PRESSURE FALLS...SUPPORTING RAPID SFC CYCLOGENESIS. THIS WILL ALLOW SIG LL THETA-E ADV TO ENSUE SUNDAY IN THE REGION WITH SIG SFC LAYER DEWPOINT RISES INTO SUNDAY NIGHT. STAUNCH LL FLOW WITH A 60 TO 70 KNOT LLJ PROGGED IN THE ECMWF...WILL BE MORE THAN ENOUGH TO SUPPORT DEEP LAYER THETA-E RISES. SNOWPACK IN PLACE WILL LIKELY SUPPORT A SATURATED BL WITH DRIZZLE AND FOG EXPECTED TO DEVELOP SUNDAY AFTERNOON INTO THE EVENING...LIKELY PERSISTING THROUGH SUNDAY NIGHT. ECMWF H7-H3 LAYER ANALYSIS REVEALS A RATHER IMPRESSIVE EML WITH STEEP MID LEVEL LAPSE RATES GIVEN STRONG LOW CENTERED WAA. H85 THETA-E APPROACHES 325K BY LATE SUNDAY NIGHT...WITH SW INDICES NEGATIVE...INDICATING A GOOD ENVIRONMENT FOR ELEVATED THUNDERSTORMS. HAVE INTRODUCED A LOW CHANCE THUNDER AT THIS POINT. ALBEIT SMALL...THERE IS A CONCERN FOR SEVERE WEATHER GIVEN INDICATED H5 JETLET IN EXCESS OF 90 KNOTS...WHICH WOULD BE CAPABLE QLCS JET DRIVEN CELLS. PERHAPS THE BIGGEST CONCERN ATTM IS FOR INCREASED FLOODING CONCERNS GIVEN FULL SNOWPACK MELT WITH THE POTENTIAL FOR HEAVY RAIN. WILL HIGHLIGHT IN AN ESF. NEGATIVE TROUGH TILT INDICATED IN FORECAST MODELS SUGGEST A NW TRACK ADJUSTMENT PER THE SFC LOW...WITH A SLOWER SYSTEM ARRIVAL POSSIBLE...IN ADDITION TO WARMER THERMAL FIELDS. HENCE DROPPED THE SNOW MENTION SUN NIGHT/TRIMMED MONDAY SNOW MENTION/AND ADJUSTED TEMPS UP. CAA WILL DOMINATE MONDAY WITH FALLING TEMPS IN THE DAYTIME PERIOD LIKELY. LINGERING LIGHT SNOW SHOWERS WILL BE POSSIBLE MAINLY NW. TUE-THUR...FAST WNW PAC ORIGIN FLOW IS EXPECTED INTO THE REGION WITH ROCKIES ENHANCED IMPULSES EXPECTED. STRONGEST PROGGED IMPULSE REMAINS IN THE WED PERIOD AND HAVE RETAINED POPS THEN...OPTING TO KEEP THE RAIN/SNOW WORDING GIVEN WARM THERMAL FIELDS. OTHERWISE...ADJUSTED TEMPS UP SOME...WITH ABOVE NORMAL TEMPS LIKELY ONCE AGAIN. && .AVIATION... 18Z TAFS...MODERATE SNOW WILL CONTINUE TO AFFECT KFWA THROUGH 20Z BEFORE DIMINISHING AS AN UPPER LEVEL DISTURBANCE AND ASSOCIATED LOW LEVEL FRONTAL BOUNDARY SAG SOUTHEAST. PERIODS OF LAKE EFFECT SNOW SHOWERS WILL ALSO AFFECT KSBN THROUGH AT LEAST EARLY EVENING. HAVE CARRIED MVFR CONDITIONS TO COVER THIS LAKE EFFECT POTENTIAL ALTHOUGH SOME SHORT LIVED IFR VSBYS MAY BE ASSOCIATED WITH THE STRONGER BANDS. NORTHWEST WINDS TO CONTINUE TO DROP OFF IN SPEED THROUGH THE REMAINDER OF THE NIGHT...EVENTUALLY BECOMING SOUTHEAST BY FRIDAY MORNING. DID MAINTAIN MVFR CIGS AT TERMINALS THIS EVENING DUE TO TRAJECTORIES UPWIND OF LAKE MICHIGAN AND WEAKENING LOW LEVEL FLOW...ALTHOUGH CONFIDENCE IS LOW IN DURATION OF THESE MVFR CIGS WITH A POSSIBILITY OF VFR CIGS AT KFWA EVEN BY LATER THIS AFTERNOON. CONDITIONS TO DETERIORATE AGAIN ON FRIDAY...ESPECIALLY TOWARD THE END OF THIS FORECAST PERIOD AS NEXT SYSTEM BRINGS A MORE SIGNIFICANT ROUND OF SNOW TO NORTHERN INDIANA. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...WINTER WEATHER ADVISORY FROM 10 AM EST /9 AM CST/ FRIDAY TO 7 AM EST /6 AM CST/ SATURDAY FOR INZ003>009-012-014-016>018. MI...WINTER WEATHER ADVISORY FROM 10 AM FRIDAY TO 7 AM EST SATURDAY FOR MIZ077>081. OH...WINTER WEATHER ADVISORY FROM 10 AM FRIDAY TO 7 AM EST SATURDAY FOR OHZ001-002-004-005-015-016. LM...SMALL CRAFT ADVISORY UNTIL 5 AM EST FRIDAY FOR LMZ043-046. && $$ SHORT TERM...MARSILI LONG TERM...JC AVIATION...MARSILI
AREA FORECAST DISCUSSION
NWS GOODLAND KS
1158 AM MST THU JAN 19 2012 .UPDATE... 1158 AM MST THU JAN 19 2012 LATEST SATELLITE IMAGERY SHOWS THAT THE COLD FRONT IS MOVING EASTWARD AWAY FROM ITS EARLIER POSITION NEAR THE KS/CO BORDER. TEMPERATURES IN EASTERN CO HAVE WARMED INTO THE 50S...WHILE TEMPERATURES IN SOUTHWESTERN NE ARE STRUGGLING TO LEAVE THE MID TEENS. HAVE ADJUSTED HIGH TEMPERATURES TO BE WARMER IN CO AND COOLER WELL BEHIND THE FRONT. CJS && .DISCUSSION... 220 AM MST THU JAN 19 2012 EARLY MORNING WV IMAGERY AND RUC H5 ANALYSIS SHOW BROAD TROUGH EXTENDING FROM GREAT LAKES ACROSS THE EASTERN US...WITH W/NW FLOW EXTENDING ACROSS THE CENTRAL PART OF THE COUNTRY. AT THE SURFACE A STRONG COLD FRONT HAS SETTLED OVER THE CWA...WITH A 20F SPREAD IN TEMPS BETWEEN THE SW PART OF THE CWA AND THE NE. TODAY-SATURDAY...WITH DRY CONDITIONS EXPECTED THE MAIN FORECAST CONCERN WILL CONTINUE TO BE TEMPERATURES AS THE PREVIOUSLY MENTIONED FRONT AND ASSOCIATED BAROCLINIC ZONE LINGERS ACROSS PORTIONS OF NORTHWEST KANSAS AND SOUTHWEST NEBRASKA. 30F SPREAD IN HIGH TEMPS CURRENTLY FORECAST FROM THE EAST TO THE WEST TODAY...WITH AREAS WEST OF THE FRONT APPROACHING THE MID 50S...AND EAST OF THE FRONT IN THE MID/UPPER 20S. BETWEEN THESE EXTREMES IT IS DIFFICULT TO PIN DOWN HIGH TEMPS CONSIDERING THE EXTREME TEMPERATURE GRADIENT THAT WILL BE IN PLACE...SO HAVE USED A GENERAL BLEND OF PREVIOUS FORECAST AND LATEST SHORT-RANGE GUIDANCE. TEMPS WILL BEGIN TO MODERATE SOME ACROSS EASTERN PARTS OF THE AREA FRIDAY...BEFORE A BACKDOOR COLD FRONT REINFORCES SHALLOW COLD AIR MASS FRIDAY AFTERNOON/EVENING. SHALLOW COLD AIR MASS BEGINS TO SCOUR OUT WITH TEMPS MODERATING AHEAD OF SHORTWAVE TROUGH MOVING TOWARDS THE GREAT BASIN...THOUGH THERE WILL STILL BE A 15-20F GRADIENT FROM EAST TO WEST. SATURDAY NIGHT...SHORTWAVE TROUGH MOVES TOWARDS THE CENTRAL ROCKIES SATURDAY NIGHT...WITH INCREASING LARGE SCALE ASCENT OVER THE CWA AFTER 06Z. NAM/GFS BOTH ARE WEAKER/QUICKER WITH THIS SYSTEM...AND KEEP CONDITIONS DRY OVER CWA. ECMWF CONTINUES TO SHOW STRONGER/WETTER SOLUTION. I WAS HESITANT TO JUMP ON THE WET ECMWF SOLUTION YET...WITH TIMING/STRENGTH STILL IN QUESTION. WITH THE AMOUNT OF LIFT PRESENT AND LIMITED MOISTURE ADVECTION I COULDNT RULE OUT SOME FLURRIES IN THE NORTH...BUT WASNT CONFIDENT ENOUGH TO ADD DURING THIS CYCLE. DR FOR THE PERIOD SUNDAY THROUGH WEDNESDAY...RELATIVELY QUIET WEATHER EXPECTED THROUGH THE ENTIRE PERIOD. A COLD FRONT WILL MOVE THROUGH THE REGION MONDAY NIGHT AND TUESDAY...HOWEVER PRECIPITATION CHANCES APPEAR THEY WILL STAY SOUTH AND EAST OF THE LOCAL FORECAST AREA. IT WILL BRING A PERIOD OF GUSTY NORTH WINDS...PROBABLY TUESDAY MORNING....AND COOLER TEMPERATURES TUESDAY AND WEDNESDAY...ALBEIT STILL ABOVE NORMAL. 024 && .AVIATION... 1050 AM MST THU JAN 19 2012 FOR THE 18Z TAFS...ARCTIC COLD CURRENTLY LOCATED NEAR THE KS/CO STATE LINE. THIS FEATURE WILL CREATE SOME UNCERTAINTY AT KGLD WITH RESPECT TO TIMING OF WIND SHIFTS...BUT A GENERAL VEER FROM EAST/SOUTHEAST TO THE SOUTH IS EXPECTED DURING THE AFTERNOON HOURS. ALSO OF NOTE ARE LOW IFR CIGS CURRENTLY LOCATED JUST TO THE NORTH OF KGLD...BUT THESE LOW CIGS ARE EXPECTED TO REMAIN TO THE NORTH OF THE TERMINAL PER WIND DIRECTION. OTHERWISE...A GENERAL WIND SHIFT WILL TAKE PLACE FROM THE EAST TO THE SOUTH/SOUTHWEST AS THE FRONT RETREATS SLOWLY TO THE EAST...WITH A WIND SHIFT TO THE NORTHWEST NEAR THE END OF THE PERIOD FRI MID/LATE MORNING. 050 && .GLD WATCHES/WARNINGS/ADVISORIES... KS...NONE. NE...NONE. CO...NONE. && $$
AREA FORECAST DISCUSSION
NWS GOODLAND KS
1050 AM MST THU JAN 19 2012 .DISCUSSION... 220 AM MST THU JAN 19 2012 EARLY MORNING WV IMAGERY AND RUC H5 ANALYSIS SHOW BROAD TROUGH EXTENDING FROM GREAT LAKES ACROSS THE EASTERN US...WITH W/NW FLOW EXTENDING ACROSS THE CENTRAL PART OF THE COUNTRY. AT THE SURFACE A STRONG COLD FRONT HAS SETTLED OVER THE CWA...WITH A 20F SPREAD IN TEMPS BETWEEN THE SW PART OF THE CWA AND THE NE. TODAY-SATURDAY...WITH DRY CONDITIONS EXPECTED THE MAIN FORECAST CONCERN WILL CONTINUE TO BE TEMPERATURES AS THE PREVIOUSLY MENTIONED FRONT AND ASSOCIATED BAROCLINIC ZONE LINGERS ACROSS PORTIONS OF NORTHWEST KANSAS AND SOUTHWEST NEBRASKA. 30F SPREAD IN HIGH TEMPS CURRENTLY FORECAST FROM THE EAST TO THE WEST TODAY...WITH AREAS WEST OF THE FRONT APPROACHING THE MID 50S...AND EAST OF THE FRONT IN THE MID/UPPER 20S. BETWEEN THESE EXTREMES IT IS DIFFICULT TO PIN DOWN HIGH TEMPS CONSIDERING THE EXTREME TEMPERATURE GRADIENT THAT WILL BE IN PLACE...SO HAVE USED A GENERAL BLEND OF PREVIOUS FORECAST AND LATEST SHORT-RANGE GUIDANCE. TEMPS WILL BEGIN TO MODERATE SOME ACROSS EASTERN PARTS OF THE AREA FRIDAY...BEFORE A BACKDOOR COLD FRONT REINFORCES SHALLOW COLD AIR MASS FRIDAY AFTERNOON/EVENING. SHALLOW COLD AIR MASS BEGINS TO SCOUR OUT WITH TEMPS MODERATING AHEAD OF SHORTWAVE TROUGH MOVING TOWARDS THE GREAT BASIN...THOUGH THERE WILL STILL BE A 15-20F GRADIENT FROM EAST TO WEST. SATURDAY NIGHT...SHORTWAVE TROUGH MOVES TOWARDS THE CENTRAL ROCKIES SATURDAY NIGHT...WITH INCREASING LARGE SCALE ASCENT OVER THE CWA AFTER 06Z. NAM/GFS BOTH ARE WEAKER/QUICKER WITH THIS SYSTEM...AND KEEP CONDITIONS DRY OVER CWA. ECMWF CONTINUES TO SHOW STRONGER/WETTER SOLUTION. I WAS HESITANT TO JUMP ON THE WET ECMWF SOLUTION YET...WITH TIMING/STRENGTH STILL IN QUESTION. WITH THE AMOUNT OF LIFT PRESENT AND LIMITED MOISTURE ADVECTION I COULDNT RULE OUT SOME FLURRIES IN THE NORTH...BUT WASNT CONFIDENT ENOUGH TO ADD DURING THIS CYCLE. DR FOR THE PERIOD SUNDAY THROUGH WEDNESDAY...RELATIVELY QUIET WEATHER EXPECTED THROUGH THE ENTIRE PERIOD. A COLD FRONT WILL MOVE THROUGH THE REGION MONDAY NIGHT AND TUESDAY...HOWEVER PRECIPITATION CHANCES APPEAR THEY WILL STAY SOUTH AND EAST OF THE LOCAL FORECAST AREA. IT WILL BRING A PERIOD OF GUSTY NORTH WINDS...PROBABLY TUESDAY MORNING....AND COOLER TEMPERATURES TUESDAY AND WEDNESDAY...ALBEIT STILL ABOVE NORMAL. 024 && .AVIATION... 1050 AM MST THU JAN 19 2012 FOR THE 18Z TAFS...ARCTIC COLD CURRENTLY LOCATED NEAR THE KS/CO STATE LINE. THIS FEATURE WILL CREATE SOME UNCERTAINTY AT KGLD WITH RESPECT TO TIMING OF WIND SHIFTS...BUT A GENERAL VEER FROM EAST/SOUTHEAST TO THE SOUTH IS EXPECTED DURING THE AFTERNOON HOURS. ALSO OF NOTE ARE LOW IFR CIGS CURRENTLY LOCATED JUST TO THE NORTH OF KGLD...BUT THESE LOW CIGS ARE EXPECTED TO REMAIN TO THE NORTH OF THE TERMINAL PER WIND DIRECTION. OTHERWISE...A GENERAL WIND SHIFT WILL TAKE PLACE FROM THE EAST TO THE SOUTH/SOUTHWEST AS THE FRONT RETREATS SLOWLY TO THE EAST...WITH A WIND SHIFT TO THE NORTHWEST NEAR THE END OF THE PERIOD FRI MID/LATE MORNING. 050 && .GLD WATCHES/WARNINGS/ADVISORIES... KS...NONE. NE...NONE. CO...NONE. && $$
AREA FORECAST DISCUSSION
NWS GOODLAND KS
425 AM MST THU JAN 19 2012 .DISCUSSION... 220 AM MST THU JAN 19 2012 EARLY MORNING WV IMAGERY AND RUC H5 ANALYSIS SHOW BROAD TROUGH EXTENDING FROM GREAT LAKES ACROSS THE EASTERN US...WITH W/NW FLOW EXTENDING ACROSS THE CENTRAL PART OF THE COUNTRY. AT THE SURFACE A STRONG COLD FRONT HAS SETTLED OVER THE CWA...WITH A 20F SPREAD IN TEMPS BETWEEN THE SW PART OF THE CWA AND THE NE. TODAY-SATURDAY...WITH DRY CONDITIONS EXPECTED THE MAIN FORECAST CONCERN WILL CONTINUE TO BE TEMPERATURES AS THE PREVIOUSLY MENTIONED FRONT AND ASSOCIATED BAROCLINIC ZONE LINGERS ACROSS PORTIONS OF NORTHWEST KANSAS AND SOUTHWEST NEBRASKA. 30F SPREAD IN HIGH TEMPS CURRENTLY FORECAST FROM THE EAST TO THE WEST TODAY...WITH AREAS WEST OF THE FRONT APPROACHING THE MID 50S...AND EAST OF THE FRONT IN THE MID/UPPER 20S. BETWEEN THESE EXTREMES IT IS DIFFICULT TO PIN DOWN HIGH TEMPS CONSIDERING THE EXTREME TEMPERATURE GRADIENT THAT WILL BE IN PLACE...SO HAVE USED A GENERAL BLEND OF PREVIOUS FORECAST AND LATEST SHORT-RANGE GUIDANCE. TEMPS WILL BEGIN TO MODERATE SOME ACROSS EASTERN PARTS OF THE AREA FRIDAY...BEFORE A BACKDOOR COLD FRONT REINFORCES SHALLOW COLD AIR MASS FRIDAY AFTERNOON/EVENING. SHALLOW COLD AIR MASS BEGINS TO SCOUR OUT WITH TEMPS MODERATING AHEAD OF SHORTWAVE TROUGH MOVING TOWARDS THE GREAT BASIN...THOUGH THERE WILL STILL BE A 15-20F GRADIENT FROM EAST TO WEST. SATURDAY NIGHT...SHORTWAVE TROUGH MOVES TOWARDS THE CENTRAL ROCKIES SATURDAY NIGHT...WITH INCREASING LARGE SCALE ASCENT OVER THE CWA AFTER 06Z. NAM/GFS BOTH ARE WEAKER/QUICKER WITH THIS SYSTEM...AND KEEP CONDITIONS DRY OVER CWA. ECMWF CONTINUES TO SHOW STRONGER/WETTER SOLUTION. I WAS HESITANT TO JUMP ON THE WET ECMWF SOLUTION YET...WITH TIMING/STRENGTH STILL IN QUESTION. WITH THE AMOUNT OF LIFT PRESENT AND LIMITED MOISTURE ADVECTION I COULDNT RULE OUT SOME FLURRIES IN THE NORTH...BUT WASNT CONFIDENT ENOUGH TO ADD DURING THIS CYCLE. DR FOR THE PERIOD SUNDAY THROUGH WEDNESDAY...RELATIVELY QUIET WEATHER EXPECTED THROUGH THE ENTIRE PERIOD. A COLD FRONT WILL MOVE THROUGH THE REGION MONDAY NIGHT AND TUESDAY...HOWEVER PRECIPITATION CHANCES APPEAR THEY WILL STAY SOUTH AND EAST OF THE LOCAL FORECAST AREA. IT WILL BRING A PERIOD OF GUSTY NORTH WINDS...PROBABLY TUESDAY MORNING....AND COOLER TEMPERATURES TUESDAY AND WEDNESDAY...ALBEIT STILL ABOVE NORMAL. 024 && .AVIATION... 425 AM MST THU JAN 19 2012 FOR THE 12Z TAFS...ARCTIC FRONT CONTINUES TO SETTLE INTO THE AREA FROM THE NORTHEAST. LIGHT WINDS WILL VEER FROM NORTHEAST TO SOUTHEAST AT KMCK...AND NORTHEAST TO SOUTHWEST AT KGLD THROUGH THIS AFTERNOON. SCATTERED TO BROKEN HIGH CLOUDS WILL CONTINUE TO STREAM OVERHEAD. /024 && .GLD WATCHES/WARNINGS/ADVISORIES... KS...NONE. NE...NONE. CO...NONE. && $$
AREA FORECAST DISCUSSION
NWS DODGE CITY KS
509 AM CST THU JAN 19 2012 .AVIATION... FOR THE 12Z TAF ISSUANCE... AT 9Z A COLD FRONT EXTENDED ACROSS SOUTHWEST KANSAS WITH THE NAM AND RUC APPEARING TO BE DOING A DECENT JOB WITH THIS SURFACE FRONT LOCATION. THEY ALSO APPEAR TO BE HANDLING THE TIGHT PRESSURE GRADIENT/GUSTY WINDS THAT HAD APPEARED AT A FEW OBSERVATION SITES IN NORTH CENTRAL KANSAS EARLIER THIS MORNING. WILL THEREFORE CONTINUE TO FOLLOW THE NAM AND RUC SOLUTIONS ON TIMING OF THIS FRONT/WIND SHIFT AS IT CROSSES THE REMAINDER OF SOUTHWEST KANSAS. FOLLOWING THE WIND SHIFT A BRIEF PERIOD OF GUSTY WINDS WILL THEN DEVELOP BUT THESE WINDS WILL START TO SUBSIDE BY MID MORNING AS AN AREA OF HIGH PRESSURE BEGINS TO BUILD INTO THE AREA FROM THE NORTH. SURFACE WINDS AT 10KTS OR LESS ARE THEN EXPECTED THROUGH THE REMAINDER OF THE AFTERNOON. THE NORTH/NORTHEAST WINDS WILL GRADUALLY SHIFT TO THE SOUTHEAST EARLY TONIGHT AS OUR SURFACE HIGH MOVES NORTHEAST OF THE AREA. BY 06Z FRIDAY BUFR SOUNDINGS SUGGESTING 45KT WINDS WILL DEVELOP JUST ABOVE THIS COLD LAYER AND THE 0-0.5KM WIND SHEAR IS FORECAST TO BE AROUND 40KTS. AS A RESULT WILL INTRODUCE A WIND SHEAR GROUP INTO THE TAFS AT 06Z.-RB && .PREV DISCUSSION... /ISSUED 328 AM CST THU JAN 19 2012/ SYNOPSIS... PAST EVENING UPPER AIR DATA ALONG WITH RECENT WATER VAPOR IMAGERY REVEALS A VERY BROAD TROUGH OVER THE EASTERN HALF OF THE COUNTRY WHILE AN EQUALLY EXTENSIVE RIDGE EXTENDS OVER THE WEST. EMBEDDED WITHIN THIS FLOW REGIME IS A 140+ KNOT UPPER JET STREAK THAT EXTENDS FROM THE PACIFIC NORTHWEST REGION INTO THE DEEP SOUTH. CLOSER TO THE SURFACE, A LARGE RESERVOIR OF ARCTIC AIR ACROSS CANADA IS INVADING THE NORTHERN PLAINS WITH 00 UTC 850 HPA PLOTS DISPLAYING A LARGE POCKET OF -30C AIR OVER NORTH DAKOTA INTO EASTERN MONTANA. RECENT SUBJECTIVE SURFACE ANALYSIS DISPLAYS THE ARCTIC FRONT SINKING SOUTHWARD OVER KANSAS WITH TEMPERATURES DROPPING QUICKLY INTO THE SINGLE DIGITS OVER CENTRAL AND NORTHERN NEBRASKA. DETERMINISTIC MODEL GUIDANCE INITIALIZED AT 00 UTC BUT VALID AT 06 UTC IS RUNNING AROUND 5 TO 10 DEGREES TOO WARM BEHIND THE FRONT. THIS STRONGLY INDICATES ANY BOUNDARY LAYER BASED MODEL THERMAL FIELDS ARE TOO WARM FOR THIS MORNING TO AFTERNOON AS WELL. DISCUSSION... DAYS 1-2... THE UPPER PATTERN WILL CHANGE LITTLE TODAY INTO THE FIRST HALF OF TONIGHT AS A TROUGH DOMINATES OVER THE EASTERN HALF OF THE COUNTRY WHILE A RIDGE PREVAILS OVER THE WEST. WITH THE STRONGEST FORCING REMAINING WELL NORTH OF KANSAS, DRY CONDITIONS WILL CONTINUE OVER THE CENTRAL PLAINS. NONETHELESS, AGEOSTROPHIC FLOW ASSOCIATED WITH THE ENTRANCE REGION OF THE AFOREMENTIONED JET STREAK, WILL ALLOW THE ARCTIC FRONT TO SLIDE SOUTHWARD INTO FAR NORTHERN OKLAHOMA AND EXTREME SOUTHWEST KANSAS BY MID MORNING. ALTHOUGH THE AIRMASS WILL REMAIN RELATIVELY SHALLOW WITH 850 HPA TEMPERATURES STAYING GENERALLY ABOVE 3C TO 5C...STRONG COLD AIR ADVECTION IN THE LOWER 500 METERS WILL KEEP SURFACE TEMPERATURES RELATIVELY COLD TODAY OVER MOST OF WESTERN AND CENTRAL KANSAS. HOWEVER, THE MAIN QUESTION IS WHERE THE FRONT WILL EXTEND OVER EXTREME SOUTHWEST KANSAS AS THE TEMPERATURE GRADIENT WILL BE TIGHT. LOCATIONS SOUTHWEST OF THE BOUNDARY WILL EXPERIENCE LIGHT WEST WINDS WITH TEMPERATURES IN THE MID 50S TO LOWER 60S WHILE LOCATIONS A GOOD 60 MILES AWAY FROM THE FRONT BUT ON THE COOL SIDE OF THE BOUNDARY WILL SEE TEMPERATURES IN THE MID 20S TO MID 30S. A NARROW 40 TO 50 MILE CORRIDOR WILL ACT AS A BUFFER ZONE BETWEEN THESE TWO EXTREMES WITH TEMPERATURES IN THE UPPER 30S TO 40S EXPECTED...BUT WHERE THIS ZONES SETS UP IS SIMPLY A GUESS AT THIS POINT. WILL AIM FOR A GARDEN CITY TO COLDWATER LINE WITH HIGHS VARYING FROM THE MID 20S AROUND HAYS, THE UPPER 30S IN DODGE, AND NEAR 60 AROUND ELKHART. LATER TONIGHT INTO FRIDAY NIGHT...A SMALL BUT POTENT UPPER WAVE WILL UNDERCUT THE RIDGE AXIS AND PLOW INTO THE CENTRAL ROCKIES BY LATE FRIDAY AFTERNOON. ALTHOUGH THE ATMOSPHERE WILL BE TOO DRY FOR THIS WAVE TO PRODUCE ANY REAL THREAT FOR PRECIPITATION, IT WILL ALLOW A REINFORCING SHOT OF ARCTIC AIR TO INVADE WESTERN AND CENTRAL KANSAS BY LATE MORNING TO EARLY AFTERNOON. HOWEVER, IN ADVANCE OF THIS FRONT PRESSURE FALLS ALONG THE FRONT RANGE REGION WILL BEGIN TO VEER WINDS AROUND TO A MORE WESTERLY DIRECTION BY SUNRISE ON FRIDAY. THIS MAY ALLOW FOR SOME MODEST WARM AIR ADVECTION DURING THE EARLY TO MID MORNING BEFORE COLDER AIR INVADES WESTERN AND CENTRAL KANSAS YET AGAIN. THE THINKING AS OF NOW IS THAT DOWNSLOPE WESTERLY WINDS WILL SPREAD AS FAR EAST AS A SCOTT CITY TO COLDWATER LINE BEFORE COLD AIR ARRIVES IN THE LATE MORNING TO EARLY AFTERNOON. THIS MAY RESULT IN TEMPERATURES BRIEFLY SPIKING INTO THE MID 40S TO MID 50S WEST OF THE ABOVE LINE BUT THEN FALLING DURING THE AFTERNOON HOURS. LOCATIONS EAST OF THIS LINE SHOULD STAY IN THE 30S. OTHERWISE, A COLD EVENING TO OVERNIGHT WILL PREVAIL AS COLDER AIR SPILLS OVER THE CENTRAL PLAINS. ANTICIPATE TEMPERATURES DROPPING INTO A 10 TO 20 DEGREE RANGE AFTER MIDNIGHT. DAYS 3-7... A TIGHT BAROCLINIC ZONE WILL ESTABLISH ITSELF ACROSS PORTIONS OF WESTERN KANSAS ON SATURDAY BETWEEN THE COLDER AIR THAT WILL INVADE THE STATE FRIDAY NIGHT AND THE DOWNSLOPE WARMING THAT IS ANTICIPATED TO SPREAD INTO THE AREA FROM THE WEST BY SATURDAY AFTERNOON. THE CURRENT FORECAST WITH HIGHS ONLY IN THE MID 30S ACROSS PORTIONS OF NORTH CENTRAL KANSAS STILL APPEARS ON TRACK GIVEN THE LATEST MODELS SOUNDINGS. FURTHER WEST 850MB TEMPERATURES INDICATING HIGHS NEAR 60 STILL WILL BE POSSIBLE AS THE 925-850MB TEMPERATURES BEGIN TO WARM. WILL HOWEVER NEED TO MONITOR THE AMOUNT OF HIGHS CLOUDS DURING THE DAY AS BOTH THE ECMWF AND GFS 300-200MB RELATIVE HUMIDITIES INCREASES ACROSS WESTERN KANSAS DURING THE AFTERNOON. THIS CLOUD COVER WILL PRECEDE AN UPPER LEVEL TROUGH WHICH AT 00Z SUNDAY IS EXPECTED TO BE LOCATED ACROSS UTAH. THIS NEXT SYSTEM WILL QUICKLY MOVE EAST INTO THE WEST CENTRAL HIGH PLAINS ON SUNDAY AS MID-HIGH LEVEL MOISTURE CONTINUES TO INCREASE. THIS INCREASE IN MOISTURE ALONG WITH IMPROVING MID LEVEL INSTABILITY MAY ALSO GIVE RISE TO SOME VIRGA, MAYBE EVEN A FEW SPRINKLES NEAR THE INTERSTATE 70 CORRIDOR. AT THIS TIME CONFIDENCE IS NOT HIGH ENOUGH YET TO INSERT MENTION OF LIGHT PRECIPITATION IN OUR NORTH BUT DID INCREASE CLOUD COVER AND LOWER TEMPERATURES. BY EARLY NEXT WEEK A SHORT WAVE RIDGE WILL QUICKLY CROSS THE ROCKIES AND MOVE OUT INTO THE PLAINS AS OUR NEXT PACIFIC UPPER LEVEL TROUGH STARTS TO WORK ITS WAY EASTWARD ACROSS THE WESTERN UNITED STATES. ONCE AGAIN MID LEVEL MOISTURE IMPROVES AS 700-500MB LAPSE RATES INCREASE. THIS WILL ONCE AGAIN BRING AN INCREASE IN CLOUDS AND POSSIBLY SOME LIGHT PRECIPITATION ON TUESDAY TO PARTS OF SOUTHWEST KANSAS IF THE GFS IS CORRECT. AGAIN CONFIDENCE IS NOT HIGH ON PRECIPITATION CHANCES GIVEN THE HEIGHT OF WHERE THE BETTER MOISTURE RETURN IS ANTICIPATED. HAVE THEREFORE DECIDED TO LEAVE THE SMALL 15-20PERCENT CHANCE OF RAIN GOING FOR OUR SOUTH/SOUTHEAST BUT DID NOT EXPAND THE CHANCES ANY FURTHER NORTH. AVIATION... FOR THE 06Z TAF ISSUANCE... THERE ISN`T A GREAT DEAL OF CHANGE IN THINKING FOR THIS TAF ISSUANCE. THE FRONT IS EXPECTED TO MOVE THROUGH HAYS (HYS) AT 07Z...THEN ROUGHLY 0830Z AT DODGE CITY (DDC) AND FINALLY SHORTLY THEREAFTER AT GARDEN CITY (GCK) AROUND 09Z. THERE WILL BE SEVERAL HOURS OF GUSTS IN THE LOW 20S KTS...BUT THE WINDS WILL GRADUALLY DECREASE DURING THE 15-18Z TIME FRAME...WITH A CONTINUE DECREASE TO LESS THAN 10 KNOTS FOR SOME TIME MIDDAY THROUGH EARLY AFTERNOON. THE WINDS WILL THEN CONTINUE TO VEER AROUND TO THE SOUTHEAST LATE IN THE DAY WITH A GRADUAL INCREASE BACK TO AROUND 12 KNOTS OR SLIGHTLY HIGHER IN RESPONSE TO RENEWED LEESIDE CYCLOGENESIS OVER EASTERN COLORADO. THE PROBABILITY OF STRATUS DEVELOPMENT IS VERY LOW GIVEN HOW SHALLOW THE ARCTIC AIRMASS IS AND HOW DRY THE LOWER ATMOSPHERE IS AS WELL. && .PRELIMINARY POINT TEMPS/POPS... DDC 39 22 48 18 / 0 0 0 0 GCK 41 23 49 17 / 0 0 0 0 EHA 60 35 56 26 / 0 0 0 0 LBL 54 27 57 20 / 0 0 0 0 HYS 26 16 36 11 / 0 0 0 0 P28 39 24 46 19 / 0 0 0 0 && .DDC WATCHES/WARNINGS/ADVISORIES... NONE. && $$ FN99/99/99
AREA FORECAST DISCUSSION
NWS GOODLAND KS
220 AM MST THU JAN 19 2012 .DISCUSSION... 220 AM MST THU JAN 19 2012 EARLY MORNING WV IMAGERY AND RUC H5 ANALYSIS SHOW BROAD TROUGH EXTENDING FROM GREAT LAKES ACROSS THE EASTERN US...WITH W/NW FLOW EXTENDING ACROSS THE CENTRAL PART OF THE COUNTRY. AT THE SURFACE A STRONG COLD FRONT HAS SETTLED OVER THE CWA...WITH A 20F SPREAD IN TEMPS BETWEEN THE SW PART OF THE CWA AND THE NE. TODAY-SATURDAY...WITH DRY CONDITIONS EXPECTED THE MAIN FORECAST CONCERN WILL CONTINUE TO BE TEMPERATURES AS THE PREVIOUSLY MENTIONED FRONT AND ASSOCIATED BAROCLINIC ZONE LINGERS ACROSS PORTIONS OF NORTHWEST KANSAS AND SOUTHWEST NEBRASKA. 30F SPREAD IN HIGH TEMPS CURRENTLY FORECAST FROM THE EAST TO THE WEST TODAY...WITH AREAS WEST OF THE FRONT APPROACHING THE MID 50S...AND EAST OF THE FRONT IN THE MID/UPPER 20S. BETWEEN THESE EXTREMES IT IS DIFFICULT TO PIN DOWN HIGH TEMPS CONSIDERING THE EXTREME TEMPERATURE GRADIENT THAT WILL BE IN PLACE...SO HAVE USED A GENERAL BLEND OF PREVIOUS FORECAST AND LATEST SHORT-RANGE GUIDANCE. TEMPS WILL BEGIN TO MODERATE SOME ACROSS EASTERN PARTS OF THE AREA FRIDAY...BEFORE A BACKDOOR COLD FRONT REINFORCES SHALLOW COLD AIR MASS FRIDAY AFTERNOON/EVENING. SHALLOW COLD AIR MASS BEGINS TO SCOUR OUT WITH TEMPS MODERATING AHEAD OF SHORTWAVE TROUGH MOVING TOWARDS THE GREAT BASIN...THOUGH THERE WILL STILL BE A 15-20F GRADIENT FROM EAST TO WEST. SATURDAY NIGHT...SHORTWAVE TROUGH MOVES TOWARDS THE CENTRAL ROCKIES SATURDAY NIGHT...WITH INCREASING LARGE SCALE ASCENT OVER THE CWA AFTER 06Z. NAM/GFS BOTH ARE WEAKER/QUICKER WITH THIS SYSTEM...AND KEEP CONDITIONS DRY OVER CWA. ECMWF CONTINUES TO SHOW STRONGER/WETTER SOLUTION. I WAS HESITANT TO JUMP ON THE WET ECMWF SOLUTION YET...WITH TIMING/STRENGTH STILL IN QUESTION. WITH THE AMOUNT OF LIFT PRESENT AND LIMITED MOISTURE ADVECTION I COULDNT RULE OUT SOME FLURRIES IN THE NORTH...BUT WASNT CONFIDENT ENOUGH TO ADD DURING THIS CYCLE. DR FOR THE PERIOD SUNDAY THROUGH WEDNESDAY...RELATIVELY QUIET WEATHER EXPECTED THROUGH THE ENTIRE PERIOD. A COLD FRONT WILL MOVE THROUGH THE REGION MONDAY NIGHT AND TUESDAY...HOWEVER PRECIPITATION CHANCES APPEAR THEY WILL STAY SOUTH AND EAST OF THE LOCAL FORECAST AREA. IT WILL BRING A PERIOD OF GUSTY NORTH WINDS...PROBABLY TUESDAY MORNING....AND COOLER TEMPERATURES TUESDAY AND WEDNESDAY...ALBEIT STILL ABOVE NORMAL. 024 && .AVIATION... 957 PM MST WED JAN 18 2012 FOR THE 06Z TAFS...COLD FRONT HAS PUSHED THROUGH KMCK WITH WINDS FROM THE NORTHEAST. FRONT WILL MEANDER BETWEEN KMCK AND KGLD THIS PERIOD WITH WINDS SOUTHWESTERLY TO SOUTHERLY AT KGLD AND EASTERLY TO SOUTHEASTERLY AT KMCK. MODELS HAVE COME INTO BETTER AGREEMENT WITH LACK OF STRATUS BEHIND THE FRONT...SO HAVE REMOVED FROM KMCK FOR THIS MORNING. EVEN THOUGH CLOUDS WILL BE PLENTIFUL THROUGH THE PERIOD...CEILING WILL BE AOA 120-150. BAS && .GLD WATCHES/WARNINGS/ADVISORIES... KS...NONE. NE...NONE. CO...NONE. && $$
AREA FORECAST DISCUSSION
NWS GRAY ME
958 PM EST FRI JAN 20 2012 .SYNOPSIS... HIGH PRESSURE WILL CREST OVER THE REGION TONIGHT AS LOW PRESSURE APPROACHES NEW ENGLAND FROM THE SOUTHWEST. LOW PRESSURE WILL PASS OUT TO SEA WELL SOUTH OF NEW ENGLAND ON SATURDAY. HIGH PRESSURE WILL BUILD IN FROM THE NORTHWEST SATURDAY NIGHT AND WILL GRADUALLY SHIFT INTO THE MARITIMES ON SUNDAY. A WARM FRONT WILL LIFT INTO SOUTHERN NEW ENGLAND ON MONDAY AND WILL BE QUICKLY FOLLOWED BY A COLD FRONT MONDAY NIGHT. A TRAILING TROUGH OF LOW PRESSURE WILL SLOWLY MOVE THROUGH NEW ENGLAND ON TUESDAY. HIGH PRESSURE WILL BUILD IN FROM THE WEST WEDNESDAY THROUGH THURSDAY..CRESTING OVER THE AREA ON FRIDAY. && .NEAR TERM /THROUGH SATURDAY/... UPDATE... VERY LITTLE CHANGE TO THE CURRENT PACKAGE. WITH LOW TDS AND A VERY DRY SOUNDING...TEMPS WILL TAKE A NOSEDIVE LATER THIS EVENING AS THE GRADIENT COLLAPSES. HIGH CLOUDINESS CONTINUES TO RACE EASTWARD HOWEVER...WHICH WILL HELP READINGS LEVEL OFF LATER TONIGHT. THIS MAY REQUIRE MIN TEMPERATURES TO BE NUDGED UPWARDS FOR THE NEXT PACKAGE UPDATE. SURFACE ANALYSIS AT 01Z SHOWING A WEAK AND ELONGATED AREA OF LOW PRESSURE APPROACHING THE WESTERN TENNESSEE BORDER. BEST PRESSURE FALLS HAVE SHIFTED INTO NORTHERN WEST VIRGINA THIS HOUR...WITH THE SYSTEM EXPECTED TO SHIFT UNDERNEATH NEW ENGLAND. LATEST 3 KM HRRR BRINGS SNOW TO THE FAR WESTERN REACHES OF NH BY 08Z...REACHING MAINE BY AROUND 11Z WHICH APPEARS TOO FAST CONSIDERING OUR DRY/ARCTIC AIR IN PLACE. WILL DELAY THE ONSET OF LIKELY POPS 2-3 HOURS LATER THAN THIS. WILL BE INCREASING POPS OVER SOUTH-CENTRAL AREAS INTO THE LOW LIKELY CATEGORY FOR TOMORROW. THIS WILL BETTER MATCH THE ACCUMULATING SNOWS (ALBIET LIGHT) THE WE ARE CURRENTLY FORECASTING...WHICH IS A DUSTING TO AN INCH. OVER SOUTHERNMOST AREAS...NEAR THE MASS BORDER...EXPECT 1-3 INCHES...WITH POSSIBLY LOCALLY HIGHER AMOUNTS. PREV DISC... CLEAR AND VERY COLD FIRST HALF OF THE NIGHT AS HIGH PRESSURE CRESTS OVER THE REGION...BUT CLOUDS WILL QUICKLY PUSH BACK INTO THE REGION AS LOW PRESSURE APPROACHES NEW ENGLAND FROM THE SOUTHWEST. CLOUDS WILL GRADUALLY LOWER AND THICKEN FROM WEST TO EAST AND SOME LIGHT SNOW OR SNOW SHOWERS WILL EDGE INTO THE CONNECTICUT VALLEY AND SOUTHERN NEW HAMPSHIRE TOWARD DAYBREAK. NOT LOOKING FOR MUCH IN THE WAY OF ACCUMULATION THROUGH 12Z WITH JUST A DUSTING LIKELY IN FAR SOUTHWEST ZONES. EXPECTING LOWS 5 TO 15 BELOW IN THE NORTH AND 5 BELOW TO 5 ABOVE IN THE SOUTH. && .SHORT TERM /SATURDAY NIGHT/... LIGHT SNOW WILL PERSIST IN SOUTHERN ZONES MAINLY DURING THE MORNING HOURS BEFORE TAPERING OFF IN THE AFTERNOON. MODELS NOT PUTTING OUT MUCH IN THE WAY OF QPF WITH MOST AREAS SEEING A TENTH OF AN INCH OR LESS BUT A DECENT FLUFF FACTOR MAY PRODUCE UP TO TWO INCHES OF SNOW IN FAR SOUTHERN NEW HAMPSHIRE. LOOKING FOR AROUND AN INCH OR LESS ACROSS THE REMAINDER OF THE FORECAST AREA. EXPECT PARTIAL CLEARING FROM NORTHWEST TO SOUTHEAST LATER IN THE AFTERNOON AS LOW PRESSURE HEADS OUT TO SEA SOUTH OF NEW ENGLAND. HIGH TEMPERATURES WON`T GET PAST THE TEENS IN THE NORTH AND MID TEENS TO LOWER 20S IN THE SOUTH. COLD HIGH PRESSURE WILL BUILD SOUTHEAST FROM CANADA SATURDAY NIGHT CLEARING SKIES AND ALLOWING TEMPERATURES TO PLUMMET ONCE AGAIN. LOOKING FOR LOWS 5 TO 15 BELOW IN THE NORTH AND 5 BELOW TO 10 ABOVE IN THE SOUTH. && .LONG TERM /SUNDAY THROUGH FRIDAY/... HIGH PRES BRINGS FAIR WX SUNDAY. LOW PRES AND A TRAILING CD FRONT APPROACH FROM THE W SUNDAY NGT AS A WRM FNT EXTENDING E FROM THE LOW HAS ANOTHER WEAKER LOW FORM ALONG THE COAST. AS THIS SYSTEM MOVES TOWARD NEW ENGLAND THE COASTAL LOW WILL COMBINE WITH THE HIGH TO THE NE TO HELP KEEP COLDER AIR IN OVER THE FCST AREA ESPECIALLY WHEN THE COASTAL FNT FORMS. GRADUALLY THOUGH THE WRM AIR STREAMING NE IN AN INCREASINGLY STRONGER S SW FLOW ALOFT EVENTUALLY ERODES THE CD AIR FORCING SN TO CHANGE TO MIX THEN TO RA FROM SW TO NE ACROSS THE FCST AREA. SN AMOUNTS MAY BE LIMITED TO MORE NRN AND NE AREAS AND AMOUNTS, IF ANY, WOULD LIKELY BE MINIMAL. ICING FROM SLEET AND FREEZING RA MAY BE MORE OF AN ISSUE DEPENDING ON HOW LONG THE CD AIR HOLDS IN AT LOW LEVELS AND AT THE SFC. MODELS VARY ON QPF AMOUNTS BUT AN INCH OF QPF THRU THE EVENT APPEARS VERY PSBL WITH A MAJORITY OF IT LIKELY FALLING AS RA. THE GFS IS SHOWING EVEN HIGHER QPF WHILE NAM AND ECMWF SHOW CONSIDERABLY LESS..AT LEAST THRU 00Z TUESDAY. THE CD FNT SWEEPS THRU MONDAY NGT WITH PRCP ENDING OR AT LEAST TAPERING OFF FROM SW TO NE. ON TUESDAY COLDER AIR FILTERS IN AND AN UPR LEVEL TROF ALONG WITH UPSLOPE LOW LVL FLOW WILL HELP PRODUCE -SHSN ACTIVITY..ESPECIALLY ACROSS THE N/MT ZONES. HIGH PRES BRINGS FAIR WX WEDNESDAY. A WEAK UPR LVL SHORT WAVE TROF MOVING THRU IN AN UPR LVL NW FLOW MAY BRING THE CHC OF SOME -SHSN ON THURSDAY...MAINLY ACROSS MORE NRN AND NE AREAS. HIGH PRES TRIES TO BUILD IN BRIEFLY FOR FRIDAY. GENERALLY USED GFS40...HPC QPF AND BLEND OF MAV/MET MOS FOR SUNDAY THRU SUNDAY NGT. USED GMOS FOR REST OF THE LONG TERM FCST... EXCEPT USED A BLEND OF GFS40 AND MEX MOS GUIDANCE FOR MAX AND MIN TEMPS. && .AVIATION /03Z SATURDAY THROUGH WEDNESDAY/... SHORT TERM...VFR TONIGHT WITH SOME AREAS OF MVFR CEILINGS/VSBY DEVELOPING OVER SOUTHERN NEW HAMPSHIRE TOWARD MORNING. MVFR/IFR CEILINGS AND VSBY MAINLY IN SOUTHERN AREAS ON SATURDAY...IMPROVING IN THE AFTERNOON. VFR SATURDAY NIGHT. LONG TERM /SUNDAY THROUGH TUESDAY/...IFR OR LIFR IN MIXED PRCP DEVELOPING SUNDAY NGT...CONTINUING THRU MONDAY AND ENDING MONDAY NGT AS IT TRANSITIONS OVER TO RA. && .MARINE... SHORT TERM...SCA IN EFFECT THROUGH EARLY EVENING. SCA`S WILL LIKELY BE NEEDED LATE SATURDAY AFTERNOON THROUGH MIDNIGHT SATURDAY NIGHT. LONG TERM /SUNDAY THROUGH TUESDAY/...WINDS AND SEAS INCREASE ON MONDAY...REACHING SCA LEVELS WITH WINDS POSSIBLY REACHING GALE FORCE...AHEAD OF LOW PRES AND A TRAILING CD FNT. CONDITIONS BRIEFLY LET UP LATE MONDAY NGT AS THE CD FNT MOVES THRU...ONLY TO INCREASE TO SCA OR GALE FORCE TUESDAY. && .GYX WATCHES/WARNINGS/ADVISORIES... ME...NONE. NH...NONE. MARINE...NONE. && $$ SYNOPSIS... NEAR TERM... SHORT TERM... LONG TERM... AVIATION... MARINE...
AREA FORECAST DISCUSSION
NWS GRAY ME
908 PM EST FRI JAN 20 2012 .SYNOPSIS... HIGH PRESSURE WILL CREST OVER THE REGION TONIGHT AS LOW PRESSURE APPROACHES NEW ENGLAND FROM THE SOUTHWEST. LOW PRESSURE WILL PASS OUT TO SEA WELL SOUTH OF NEW ENGLAND ON SATURDAY. HIGH PRESSURE WILL BUILD IN FROM THE NORTHWEST SATURDAY NIGHT AND WILL GRADUALLY SHIFT INTO THE MARITIMES ON SUNDAY. A WARM FRONT WILL LIFT INTO SOUTHERN NEW ENGLAND ON MONDAY AND WILL BE QUICKLY FOLLOWED BY A COLD FRONT MONDAY NIGHT. A TRAILING TROUGH OF LOW PRESSURE WILL SLOWLY MOVE THROUGH NEW ENGLAND ON TUESDAY. HIGH PRESSURE WILL BUILD IN FROM THE WEST WEDNESDAY THROUGH THURSDAY..CRESTING OVER THE AREA ON FRIDAY. && .NEAR TERM /THROUGH SATURDAY/... UPDATE... VERY LITTLE CHANGE TO THE CURRENT PACKAGE. WITH LOW TDS AND A VERY DRY SOUNDING...TEMPS WILL TAKE A NOSEDIVE LATER THIS EVENING AS THE GRADIENT COLLAPSES. HIGH CLOUDINESS CONTINUES TO RACE EASTWARD HOWEVER...WHICH WILL HELP READINGS LEVEL OFF LATER TONIGHT. THIS MAY REQUIRE MIN TEMPERATURES TO BE NUDGED UPWARDS FOR THE NEXT PACKAGE UPDATE. SURFACE ANALYSIS AT 01Z SHOWING A WEAK AND ELONGATED AREA OF LOW PRESSURE APPROACHING THE WESTERN TENNESSEE BORDER. BEST PRESSURE FALLS HAVE SHIFTED INTO NORTHERN WEST VIRGINA THIS HOUR...WITH THE SYSTEM EXPECTED TO SHIFT UNDERNEATH NEW ENGLAND. LATEST 3 KM HRRR BRINGS SNOW TO THE FAR WESTERN REACHES OF NH BY 08Z...REACHING MAINE BY AROUND 11Z WHICH APPEARS TOO FAST CONSIDERING OUR DRY/ARCTIC AIR IN PLACE. WILL DELAY THE ONSET OF LIKELY POPS 2-3 HOURS LATER THAN THIS. WILL BE INCREASING POPS OVER SOUTH-CENTRAL AREAS INTO THE LOW LIKELY CATEGORY FOR TOMORROW. THIS WILL BETTER MATCH THE ACCUMULATING SNOWS (ALBIET LIGHT) THE WE ARE CURRENTLY FORECASTING...WHICH IS A DUSTING TO AN INCH. OVER SOUTHERNMOST AREAS...NEAR THE MASS BORDER...EXPECT 1-3 INCHES...WITH POSSIBLY LOCALLY HIGHER AMOUNTS. PREV DISC... CLEAR AND VERY COLD FIRST HALF OF THE NIGHT AS HIGH PRESSURE CRESTS OVER THE REGION...BUT CLOUDS WILL QUICKLY PUSH BACK INTO THE REGION AS LOW PRESSURE APPROACHES NEW ENGLAND FROM THE SOUTHWEST. CLOUDS WILL GRADUALLY LOWER AND THICKEN FROM WEST TO EAST AND SOME LIGHT SNOW OR SNOW SHOWERS WILL EDGE INTO THE CONNECTICUT VALLEY AND SOUTHERN NEW HAMPSHIRE TOWARD DAYBREAK. NOT LOOKING FOR MUCH IN THE WAY OF ACCUMULATION THROUGH 12Z WITH JUST A DUSTING LIKELY IN FAR SOUTHWEST ZONES. EXPECTING LOWS 5 TO 15 BELOW IN THE NORTH AND 5 BELOW TO 5 ABOVE IN THE SOUTH. && .SHORT TERM /SATURDAY NIGHT/... LIGHT SNOW WILL PERSIST IN SOUTHERN ZONES MAINLY DURING THE MORNING HOURS BEFORE TAPERING OFF IN THE AFTERNOON. MODELS NOT PUTTING OUT MUCH IN THE WAY OF QPF WITH MOST AREAS SEEING A TENTH OF AN INCH OR LESS BUT A DECENT FLUFF FACTOR MAY PRODUCE UP TO TWO INCHES OF SNOW IN FAR SOUTHERN NEW HAMPSHIRE. LOOKING FOR AROUND AN INCH OR LESS ACROSS THE REMAINDER OF THE FORECAST AREA. EXPECT PARTIAL CLEARING FROM NORTHWEST TO SOUTHEAST LATER IN THE AFTERNOON AS LOW PRESSURE HEADS OUT TO SEA SOUTH OF NEW ENGLAND. HIGH TEMPERATURES WON`T GET PAST THE TEENS IN THE NORTH AND MID TEENS TO LOWER 20S IN THE SOUTH. COLD HIGH PRESSURE WILL BUILD SOUTHEAST FROM CANADA SATURDAY NIGHT CLEARING SKIES AND ALLOWING TEMPERATURES TO PLUMMET ONCE AGAIN. LOOKING FOR LOWS 5 TO 15 BELOW IN THE NORTH AND 5 BELOW TO 10 ABOVE IN THE SOUTH. && .LONG TERM /SUNDAY THROUGH FRIDAY/... HIGH PRES BRINGS FAIR WX SUNDAY. LOW PRES AND A TRAILING CD FRONT APPROACH FROM THE W SUNDAY NGT AS A WRM FNT EXTENDING E FROM THE LOW HAS ANOTHER WEAKER LOW FORM ALONG THE COAST. AS THIS SYSTEM MOVES TOWARD NEW ENGLAND THE COASTAL LOW WILL COMBINE WITH THE HIGH TO THE NE TO HELP KEEP COLDER AIR IN OVER THE FCST AREA ESPECIALLY WHEN THE COASTAL FNT FORMS. GRADUALLY THOUGH THE WRM AIR STREAMING NE IN AN INCREASINGLY STRONGER S SW FLOW ALOFT EVENTUALLY ERODES THE CD AIR FORCING SN TO CHANGE TO MIX THEN TO RA FROM SW TO NE ACROSS THE FCST AREA. SN AMOUNTS MAY BE LIMITED TO MORE NRN AND NE AREAS AND AMOUNTS, IF ANY, WOULD LIKELY BE MINIMAL. ICING FROM SLEET AND FREEZING RA MAY BE MORE OF AN ISSUE DEPENDING ON HOW LONG THE CD AIR HOLDS IN AT LOW LEVELS AND AT THE SFC. MODELS VARY ON QPF AMOUNTS BUT AN INCH OF QPF THRU THE EVENT APPEARS VERY PSBL WITH A MAJORITY OF IT LIKELY FALLING AS RA. THE GFS IS SHOWING EVEN HIGHER QPF WHILE NAM AND ECMWF SHOW CONSIDERABLY LESS..AT LEAST THRU 00Z TUESDAY. THE CD FNT SWEEPS THRU MONDAY NGT WITH PRCP ENDING OR AT LEAST TAPERING OFF FROM SW TO NE. ON TUESDAY COLDER AIR FILTERS IN AND AN UPR LEVEL TROF ALONG WITH UPSLOPE LOW LVL FLOW WILL HELP PRODUCE -SHSN ACTIVITY..ESPECIALLY ACROSS THE N/MT ZONES. HIGH PRES BRINGS FAIR WX WEDNESDAY. A WEAK UPR LVL SHORT WAVE TROF MOVING THRU IN AN UPR LVL NW FLOW MAY BRING THE CHC OF SOME -SHSN ON THURSDAY...MAINLY ACROSS MORE NRN AND NE AREAS. HIGH PRES TRIES TO BUILD IN BRIEFLY FOR FRIDAY. GENERALLY USED GFS40...HPC QPF AND BLEND OF MAV/MET MOS FOR SUNDAY THRU SUNDAY NGT. USED GMOS FOR REST OF THE LONG TERM FCST... EXCEPT USED A BLEND OF GFS40 AND MEX MOS GUIDANCE FOR MAX AND MIN TEMPS. && .AVIATION /02Z SATURDAY THROUGH WEDNESDAY/... SHORT TERM...VFR TONIGHT WITH SOME AREAS OF MVFR CEILINGS/VSBY DEVELOPING OVER SOUTHERN NEW HAMPSHIRE TOWARD MORNING. MVFR/IFR CEILINGS AND VSBY MAINLY IN SOUTHERN AREAS ON SATURDAY...IMPROVING IN THE AFTERNOON. VFR SATURDAY NIGHT. LONG TERM /SUNDAY THROUGH TUESDAY/...IFR OR LIFR IN MIXED PRCP DEVELOPING SUNDAY NGT...CONTINUING THRU MONDAY AND ENDING MONDAY NGT AS IT TRANSITIONS OVER TO RA. && .MARINE... SHORT TERM...SCA IN EFFECT THROUGH EARLY EVENING. SCA`S WILL LIKELY BE NEEDED LATE SATURDAY AFTERNOON THROUGH MIDNIGHT SATURDAY NIGHT. LONG TERM /SUNDAY THROUGH TUESDAY/...WINDS AND SEAS INCREASE ON MONDAY...REACHING SCA LEVELS WITH WINDS POSSIBLY REACHING GALE FORCE...AHEAD OF LOW PRES AND A TRAILING CD FNT. CONDITIONS BRIEFLY LET UP LATE MONDAY NGT AS THE CD FNT MOVES THRU...ONLY TO INCREASE TO SCA OR GALE FORCE TUESDAY. && .GYX WATCHES/WARNINGS/ADVISORIES... ME...NONE. NH...NONE. MARINE...NONE. && $$
AREA FORECAST DISCUSSION
NWS GRAY ME
820 PM EST FRI JAN 20 2012 .SYNOPSIS... HIGH PRESSURE WILL CREST OVER THE REGION TONIGHT AS LOW PRESSURE APPROACHES NEW ENGLAND FROM THE SOUTHWEST. LOW PRESSURE WILL PASS OUT TO SEA WELL SOUTH OF NEW ENGLAND ON SATURDAY. HIGH PRESSURE WILL BUILD IN FROM THE NORTHWEST SATURDAY NIGHT AND WILL GRADUALLY SHIFT INTO THE MARITIMES ON SUNDAY. A WARM FRONT WILL LIFT INTO SOUTHERN NEW ENGLAND ON MONDAY AND WILL BE QUICKLY FOLLOWED BY A COLD FRONT MONDAY NIGHT. A TRAILING TROUGH OF LOW PRESSURE WILL SLOWLY MOVE THROUGH NEW ENGLAND ON TUESDAY. HIGH PRESSURE WILL BUILD IN FROM THE WEST WEDNESDAY THROUGH THURSDAY..CRESTING OVER THE AREA ON FRIDAY. && .NEAR TERM /THROUGH SATURDAY/... UPDATE... VERY LITTLE CHANGE TO THE CURRENT PACKAGE. WITH LOW TDS AND A VERY DRY SOUNDING...TEMPS WILL TAKE A NOSEDIVE LATER THIS EVENING AS THE GRADIENT COLLAPSES. LATEST 3 KM HRRR BRINGS SNOW TO THE FAR WESTERN REACHES OF NH BY 08Z...REACHING MAINE BY AROUND 11Z WHICH APPEARS TOO FAST CONSIDERING OUR DRY/ARCTIC AIR IN PLACE. WILL BE INCREASING POPS OVER SOUTH-CENTRAL AREAS INTO THE LOW LIKELY CATEGORY FOR TOMORROW. THIS WILL BETTER MATCH THE ACCUMULATING SNOWS (ALBIET LIGHT) THE WE ARE CURRENTLY FORECASTING...WHICH IS A DUSTING TO AN INCH. PREV DISC... CLEAR AND VERY COLD FIRST HALF OF THE NIGHT AS HIGH PRESSURE CRESTS OVER THE REGION...BUT CLOUDS WILL QUICKLY PUSH BACK INTO THE REGION AS LOW PRESSURE APPROACHES NEW ENGLAND FROM THE SOUTHWEST. CLOUDS WILL GRADUALLY LOWER AND THICKEN FROM WEST TO EAST AND SOME LIGHT SNOW OR SNOW SHOWERS WILL EDGE INTO THE CONNECTICUT VALLEY AND SOUTHERN NEW HAMPSHIRE TOWARD DAYBREAK. NOT LOOKING FOR MUCH IN THE WAY OF ACCUMULATION THROUGH 12Z WITH JUST A DUSTING LIKELY IN FAR SOUTHWEST ZONES. EXPECTING LOWS 5 TO 15 BELOW IN THE NORTH AND 5 BELOW TO 5 ABOVE IN THE SOUTH. && .SHORT TERM /SATURDAY NIGHT/... LIGHT SNOW WILL PERSIST IN SOUTHERN ZONES MAINLY DURING THE MORNING HOURS BEFORE TAPERING OFF IN THE AFTERNOON. MODELS NOT PUTTING OUT MUCH IN THE WAY OF QPF WITH MOST AREAS SEEING A TENTH OF AN INCH OR LESS BUT A DECENT FLUFF FACTOR MAY PRODUCE UP TO TWO INCHES OF SNOW IN FAR SOUTHERN NEW HAMPSHIRE. LOOKING FOR AROUND AN INCH OR LESS ACROSS THE REMAINDER OF THE FORECAST AREA. EXPECT PARTIAL CLEARING FROM NORTHWEST TO SOUTHEAST LATER IN THE AFTERNOON AS LOW PRESSURE HEADS OUT TO SEA SOUTH OF NEW ENGLAND. HIGH TEMPERATURES WON`T GET PAST THE TEENS IN THE NORTH AND MID TEENS TO LOWER 20S IN THE SOUTH. COLD HIGH PRESSURE WILL BUILD SOUTHEAST FROM CANADA SATURDAY NIGHT CLEARING SKIES AND ALLOWING TEMPERATURES TO PLUMMET ONCE AGAIN. LOOKING FOR LOWS 5 TO 15 BELOW IN THE NORTH AND 5 BELOW TO 10 ABOVE IN THE SOUTH. && .LONG TERM /SUNDAY THROUGH FRIDAY/... HIGH PRES BRINGS FAIR WX SUNDAY. LOW PRES AND A TRAILING CD FRONT APPROACH FROM THE W SUNDAY NGT AS A WRM FNT EXTENDING E FROM THE LOW HAS ANOTHER WEAKER LOW FORM ALONG THE COAST. AS THIS SYSTEM MOVES TOWARD NEW ENGLAND THE COASTAL LOW WILL COMBINE WITH THE HIGH TO THE NE TO HELP KEEP COLDER AIR IN OVER THE FCST AREA ESPECIALLY WHEN THE COASTAL FNT FORMS. GRADUALLY THOUGH THE WRM AIR STREAMING NE IN AN INCREASINGLY STRONGER S SW FLOW ALOFT EVENTUALLY ERODES THE CD AIR FORCING SN TO CHANGE TO MIX THEN TO RA FROM SW TO NE ACROSS THE FCST AREA. SN AMOUNTS MAY BE LIMITED TO MORE NRN AND NE AREAS AND AMOUNTS, IF ANY, WOULD LIKELY BE MINIMAL. ICING FROM SLEET AND FREEZING RA MAY BE MORE OF AN ISSUE DEPENDING ON HOW LONG THE CD AIR HOLDS IN AT LOW LEVELS AND AT THE SFC. MODELS VARY ON QPF AMOUNTS BUT AN INCH OF QPF THRU THE EVENT APPEARS VERY PSBL WITH A MAJORITY OF IT LIKELY FALLING AS RA. THE GFS IS SHOWING EVEN HIGHER QPF WHILE NAM AND ECMWF SHOW CONSIDERABLY LESS..AT LEAST THRU 00Z TUESDAY. THE CD FNT SWEEPS THRU MONDAY NGT WITH PRCP ENDING OR AT LEAST TAPERING OFF FROM SW TO NE. ON TUESDAY COLDER AIR FILTERS IN AND AN UPR LEVEL TROF ALONG WITH UPSLOPE LOW LVL FLOW WILL HELP PRODUCE -SHSN ACTIVITY..ESPECIALLY ACROSS THE N/MT ZONES. HIGH PRES BRINGS FAIR WX WEDNESDAY. A WEAK UPR LVL SHORT WAVE TROF MOVING THRU IN AN UPR LVL NW FLOW MAY BRING THE CHC OF SOME -SHSN ON THURSDAY...MAINLY ACROSS MORE NRN AND NE AREAS. HIGH PRES TRIES TO BUILD IN BRIEFLY FOR FRIDAY. GENERALLY USED GFS40...HPC QPF AND BLEND OF MAV/MET MOS FOR SUNDAY THRU SUNDAY NGT. USED GMOS FOR REST OF THE LONG TERM FCST... EXCEPT USED A BLEND OF GFS40 AND MEX MOS GUIDANCE FOR MAX AND MIN TEMPS. && .AVIATION /01Z SATURDAY THROUGH WEDNESDAY/... SHORT TERM...VFR TONIGHT WITH SOME AREAS OF MVFR CEILINGS/VSBY DEVELOPING OVER SOUTHERN NEW HAMPSHIRE TOWARD MORNING. MVFR/IFR CEILINGS AND VSBY MAINLY IN SOUTHERN AREAS ON SATURDAY...IMPROVING IN THE AFTERNOON. VFR SATURDAY NIGHT. LONG TERM /SUNDAY THROUGH TUESDAY/...IFR OR LIFR IN MIXED PRCP DEVELOPING SUNDAY NGT...CONTINUING THRU MONDAY AND ENDING MONDAY NGT AS IT TRANSITIONS OVER TO RA. && .MARINE... SHORT TERM...SCA IN EFFECT THROUGH EARLY EVENING. SCA`S WILL LIKELY BE NEEDED LATE SATURDAY AFTERNOON THROUGH MIDNIGHT SATURDAY NIGHT. LONG TERM /SUNDAY THROUGH TUESDAY/...WINDS AND SEAS INCREASE ON MONDAY...REACHING SCA LEVELS WITH WINDS POSSIBLY REACHING GALE FORCE...AHEAD OF LOW PRES AND A TRAILING CD FNT. CONDITIONS BRIEFLY LET UP LATE MONDAY NGT AS THE CD FNT MOVES THRU...ONLY TO INCREASE TO SCA OR GALE FORCE TUESDAY. && .GYX WATCHES/WARNINGS/ADVISORIES... ME...NONE. NH...NONE. MARINE...NONE. && $$
AREA FORECAST DISCUSSION
NWS GRAY ME
501 PM EST THU JAN 19 2012 .SYNOPSIS... WEAK LOW PRESSURE WILL MOVE EAST THROUGH NEW ENGLAND AND THE GULF OF MAINE OVERNIGHT. LOW PRESSURE WILL SHIFT INTO THE MARITIMES ON FRIDAY AS HIGH PRESSURE BUILDS IN FROM THE WEST. HIGH PRESSURE WILL SHIFT EAST FRIDAY NIGHT AS WEAK LOW PRESSURE APPROACHES NEW ENGLAND FROM THE SOUTHWEST. LOW PRESSURE WILL PASS OUT TO SEA SOUTH OF NEW ENGLAND ON SATURDAY. HIGH PRESSURE WILL BUILD IN FROM THE NORTHWEST SATURDAY NIGHT AND SUNDAY. LOW PRESSURE LIFTING NORTHEAST OUT OF THE NORTHERN GREAT LAKES WILL DRIVE A COLD FRONT TOWARD NEW ENGLAND ON MONDAY. THE FRONT WILL CROSS THE AREA MONDAY NIGHT WITH A TRAILING TROUGH OF LOW PRESSURE MOVING THROUGH THE REGION ON TUESDAY. HIGH PRESSURE WILL BUILD IN FROM THE NORTHWEST ON WEDNESDAY. LOW PRESSURE WILL PASS SOUTH OF NEW ENGLAND ON THURSDAY. && .NEAR TERM /THROUGH TONIGHT/... UPDATE... ALSO...LATEST HRRR MODEL UPDATE HAS A GOOD HANDLE WITH OCEAN EFFECT SNOW SHOWERS ENTERING ROCKINGHAM AND YORK COUNTIES THIS HOUR. HAVE UPPED POPS QUITE A BIT FOR THIS AREA TO ACCOUNT FOR THIS LOCAL PCPN. -SHSN WILL SPREAD NORTHWARD IN THE NEXT HOUR OR TWO INTO THE PWM AND POSSIBLY THE NHZ AREAS. HAVE UPDATED GRIDS TO INCREASE CLOUD COVER OVERNIGHT TO OVERCAST CONDITIONS WITH ADVISORIES IN EFFECT. REST OF THE GRIDS WILL REMAIN RELATIVELY UNCHANGED WITH ADVISORIES CONTINUING FOR THE ERN HALF OF THE FORECAST AREA. PREV DISC... WEAK LOW PRESSURE APPROACHING FROM THE WEST WILL BRING A BRIEF ROUND OF LIGHT TO MODERATE SNOW TO THE REGION OVERNIGHT. LOW PRESSURE STILL FORECAST TO RE-DEVELOP OVER SOUTHERN NEW ENGLAND AND MOVE INTO THE GULF OF MAINE BUT MODELS NOT AS STRONG WITH THIS SYSTEM TODAY AND QPF FOR THE EVENT HAS DROPPED OFF SOMEWHAT. EXPECT SNOW TO PUSH INTO THE CONNECTICUT VALLEY EARLY THIS EVENING AND QUICKLY OVER-SPREAD THE REMAINDER OF THE FORECAST AREA THROUGH MIDNIGHT. WILL STILL BE GOING WITH THE CURRENT ADVISORIES FOR SOUTHERN AND COASTAL MAINE EXCLUDING YORK COUNTY FOR THE OVERNIGHT HOURS. HAVE NOT CHANGED ACCUMULATIONS MUCH FROM YESTERDAY WITH 2 TO 4 INCHES OF ACCUMULATION EXPECTED ACROSS MUCH OF NEW HAMPSHIRE AND EXTREME SOUTHWEST MAINE. REMAINDER OF SOUTHERN AND COASTAL MAINE WILL SEE 3 TO 6 INCHES OF SNOWFALL THROUGH EARLY FRIDAY MORNING. EXPECT SNOW TO QUICKLY END IN NEW HAMPSHIRE AND SOUTHWEST MAINE BEFORE DAYBREAK ON FRIDAY. SHOULD BE A MUCH WARMER NIGHT WITH TEMPS IN THE LOWER TO MID TEENS IN THE NORTH AND MID TEENS TO LOWER 20S IN THE SOUTH. && .SHORT TERM /FRIDAY THROUGH FRIDAY NIGHT/... HIGH PRESSURE BUILDING IN FROM THE WEST WILL BRINGING CLEARING SKIES AND MOSTLY SUNNY WEATHER TO MOST OF THE AREA ON FRIDAY. SHOULD SEE MORNING CLOUDS CLEARING OUT OF THE MOUNTAINS AND FAR EASTERN ZONES BY NOON. EXPECT TEMPS TO RANGE THROUGH THE TEENS IN THE NORTH AND THROUGH THE 20S AND LOWER 30S IN THE SOUTH. MID HIGH LEVEL CLOUDINESS WILL BE ON THE INCREASE FRIDAY NIGHT AS WEAK OVER-RUNNING PATTERN SHIFTS INTO THE NORTHEAST AHEAD OF LOW PRESSURE MOVING INTO THE MID ATLANTIC STATES. WILL INTRODUCE LOW CHANCE POPS INTO SOUTHERN NEW HAMPSHIRE AFTER MIDNIGHT BUT EXPECT LITTLE IF ANY ACCUMULATION THROUGH SATURDAY MORNING. LOW TEMPS WILL RANGE FROM ZERO TO 10 BELOW IN THE NORTH AND 5 TO 15 ABOVE IN THE SOUTH. && .LONG TERM /SATURDAY THROUGH THURSDAY/... MODELS TRACK WEAK SFC LOW OFF THE MID ATLANTIC COAST E AND OUT TO SEA ON SATURDAY. THIS WILL PRODUCE -SN ACROSS THE FCST AREA WITH LGT ACCUMULATIONS PSBL. HIGHEST CHC OF SN AND HIGHEST ACCUMULATIONS OVER MORE SRN AREAS CLOSER TO THE LOW WITH LOWEST CHC AND ACCUMULATION TO THE N. VERTICAL TEMP PROFILE CD ENOUGH TO SUPPORT ALL SN FOR THIS EVENT. THE LOW MOVES OUT TO SEA FAIRLY QUICKLY WITH -SN ENDING FROM W TO E IN THE AFTERNOON. HIGH PRES FOLLOWS WITH FAIR WX SATURDAY NGT AND SUNDAY. THE HIGH MOVES OUT TO THE E SUNDAY NGT AS THE UPR LVL RIDGE CRESTS ALONG THE E COAST. A STRONG UPR LVL CUTOFF SYSTEM OVER THE UPPER MID WEST CREATES A FAIRLY STRONG SFC LOW OVER THE GREAT LAKES THAT WILL TRACK SLOWLY E WITH A TRAILING CD FNT EXTENDING TO THE S. AHEAD OF THIS SYSTEM INCREASING S SW FLOW FROM SFC TO H5 BRINGS IN MUCH WARMER AIR ALOFT AND EVENTUALLY TO THE SFC AS PRCP EVENTUALLY MOVES IN LATE SUNDAY NGT AND MONDAY. MAY BE SOME -SN OR MIXED SN AND ICE TO BEGIN WITH BUT GRADUALLY PRPC CHANGES OVER TO RA FOR MONDAY AND MONDAY NGT THOUGH SOME -FZRA STILL PSBL ACROSS THE NRN TIER OF ZONES WHERE IT WILL TAKE THE LONGEST TO SCOUR OUT THE CD AIR AT THE SFC. THE CD FNT MOVES THRU BY TUESDAY MORNING WITH COLDER AIR FOLLOWING THE FNT AS TEMPS LIKELY TO FALL DURING THE DAY AFTER MILD PREDAWN READINGS. A SECONDARY UPR LVL TROF MOVES THRU WHICH MAY PRODUCE A FEW -SHSN BUT THE N/MT ZONES HAVE THE BEST CHC OF -SHSN DUE TO DEVELOPING UPSLOPE FLOW IN THE CD AIR ADVECTION BEHIND THE FNT. HIGH PRES BRINGS FAIR WX WEDNESDAY FOLLOWED BY A FAST MOVING SFC LOW THAT WILL TRACK TO OUR S BRINGING THE CHC OF -SN WEDNESDAY NGT AND THURSDAY. GENERALLY USED GFS40...HPC QPF AND BLEND OF MAV/MET MOS FOR SATURDAY THRU SATURDAY NGT. USED GMOS FOR REST OF THE LONG TERM FCST... EXCEPT USED A BLEND OF GFS40 AND MEX MOS GUIDANCE FOR MAX AND MIN TEMPS. && .AVIATION /19Z THURSDAY THROUGH TUESDAY/... SHORT TERM...MVFR/IFR CEILINGS AND VSBY DEVELOPING THIS EVENING...IMPROVING TO VFR ON FRIDAY. VFR FRIDAY NIGHT. LONG TERM /SATURDAY THROUGH MONDAY/...IFR PSBL WITH -SN SATURDAY. IFR OR LIFR PSBL WITH MIXED PRCP DEVELOPING LATE SUNDAY NGT AND CONTINUING THRU MONDAY. && .MARINE... SHORT TERM...SMALL CRAFT ADVISORY IN EFFECT THIS EVENING THROUGH FRIDAY. LONG TERM /SATURDAY THROUGH MONDAY/...CONDITIONS BELOW SCA LEVELS SATURDAY THRU SUNDAY NGT...THEN INCREASE TO SCA LEVELS OR PSBL GALES MONDAY INTO MONDAY NGT IN STRENGTHEN S SW FLOW AHEAD OF THE CD FNT. WINDS SHIFT TO THE W AS THE FNT MOVES OUT TO SEA AND CONT AT SCA OR PSBL GALE LEVELS ON TUESDAY. && .GYX WATCHES/WARNINGS/ADVISORIES... ME...WINTER WEATHER ADVISORY FROM 9 PM THIS EVENING TO 11 AM EST FRIDAY FOR MEZ012>014-019>022-024>028. NH...NONE. MARINE...SMALL CRAFT ADVISORY FROM 10 PM THIS EVENING TO 7 PM EST FRIDAY FOR ANZ150>154. && $$
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
424 PM EST THU JAN 19 2012 .SYNOPSIS... A FAST MOVING COLD FRONT WILL BRING A PERIOD OF ACCUMULATING SNOW EARLY TONIGHT. HIGH PRESSURE WILL THEN ALLOW FOR A BRIEF BREAK FROM WINTRY PRECIPITATION EARLY ON FRIDAY. LOW PRESSURE, MOVING NORTHEAST FROM TEXAS, WILL CROSS JUST SOUTH OF THE AREA, BRINGING A WINTRY MIX FOR FRIDAY NIGHT AND SATURDAY. && .NEAR TERM /UNTIL 6 AM FRIDAY MORNING/... THE LATEST RUC MID-LEVEL ANALYSIS INDICATES THE UPPER OHIO VALLEY IN A ZONAL FLOW AS A TROUGH MOVES ACROSS THE EASTERN GREAT LAKES. AT THE SURFACE, A 998MB LOW IS LOCATED NORTHEAST OF MICHIGAN. A COLD FRONT EXTENDS SOUTH OF THIS FEATURE INTO OHIO. AHEAD OF THE FRONT, AN AREA OF LIGHT SNOW IS PUSHING INTO EASTERN OHIO AND WESTERN PA. THE SNOW INCREASES IN INTENSITY CLOSER TO THE FRONT, WITH MODERATE SNOW REPORTED A FEW OBS UPSTREAM IN NORTHWEST OHIO. THIS EVENING...THE COLD FRONT WILL QUICKLY SLIDE SOUTHEAST TOWARD THE AREA, WITH THE RUC/HRRR WIND SHIFT SUPPORTING THE FRONT REACHING A ZANESVILLE-NEW PHILADELPHIA-FRANKLIN LINE BY 00Z. LIGHT SNOW WILL INCREASE IN INTENSITY AT TIMES, REDUCING VISIBILITIES THIS EVENING. A FACTOR IN THE SNOWFALL ACCUMULATION AT LEAST INITIALLY WILL BE SURFACE TEMPS, WITH AREAS SOUTH OF I-70 IN THE MID TO UPPER 30S. THIS WILL LIMIT SNOWFALL ACCUMULATION THERE INITIALLY. THUS FORECAST INTO THE EARLY EVENING IS FOR AROUND AN INCH NORTH OF I-70 AND FOR A HALF OF AN INCH OR LESS SOUTHWARD. TONIGHT...THE COLD FRONT WILL QUICKLY SLIDE SOUTHEAST ACROSS THE UPPER OHIO VALLEY, PUSHING SOUTHEAST OF THE RIDGES BY 03Z FRI. THE BEST CHANCE FOR SNOW ACCUMULATION AND POTENTIALLY HAZARDOUS TRAVEL WILL BE AROUND SUNSET THROUGH MIDNIGHT AS SNOW PUSHES ACROSS THE AREA. SNOW WILL BEGIN TO TAPER OFF BEHIND THE FRONT WITH JUST A FEW LINGERING SNOW SHOWERS ALONG THE I-80 CORRIDOR AND EASTERN RIDGES BY DAWN. MOSTLY AROUND AN ADDITIONAL INCH OF SNOWFALL WILL BE POSSIBLE TONIGHT, WITH 1 TO 3 POSSIBLE IN LOCALIZED AREAS AND THE EASTERN RIDGES. STRONG COLD AIR ADVECTION IN THE WAKE OF THE FRONT WILL ALLOW FOR LOWS RANGING FROM THE TEENS ACROSS NORTH- CENTRAL WV TO THE LOWER TEENS NORTH OF THE PITTSBURGH METRO. TOTAL SNOWFALL FOR THIS AFTERNOON THROUGH TONIGHT WILL GENERALLY BE 1 TO 2 INCHES ACROSS MUCH OF THE AREA. LOCALIZED AREAS OF UP TO 3 INCHES WILL BE POSSIBLE NORTH OF THE PITTSBURGH METRO AND ACROSS THE EASTERN RIDGES WITH COOLER TEMPS AT THE ONSET OF THE SNOW. IN ADDITION, MOST LOWLAND AREAS SOUTH OF I-70 WILL SEE LESS AN INCH. ALTHOUGH SNOW AMOUNTS FORECAST ARE MOSTLY SUB-ADVISORY AMOUNTS, WILL CONTINUE THE WINTER WEATHER ADVISORY FOR AREAS NORTH OF PITTSBURGH DUE TO TIMING OF THE SNOW IMPACTING THE EVENING COMMUTE. && .SHORT TERM /6 AM FRIDAY MORNING THROUGH SATURDAY/... THERE IS OPERATIONAL MODEL AGREEMENT TO BEGIN THIS PERIOD THAT HIGH PRESSURE WILL KEEP THE EARLY PORTION OF THE DAY DRY ACROSS THE AREA. AFTER 18Z, AN INVERTED TROUGH OF LOW PRESSURE EXTENDING FROM TEXAS INTO THE TENNESSEE VALLEY WILL SERVE TO DRAW MOISTURE FROM THE GULF INTO THE AREA AS ANOTHER WAVE MOVES ACROSS THE MIDWEST. THIS WILL CREATE A COMPLICATED MIXED PRECIPITATION SCENARIO FOR THE UPPER OHIO VALLEY FOR FRIDAY NIGHT INTO EARLY SATURDAY. FORECAST CONSISTS OF A BLEND OF THE NAM/ECMWF/SREF WITH THE GFS CONSIDERED A COLD OUTLIER. SURFACE LOW AND INVERTED TROUGH FROM THE TN VALLEY WILL MERGE WITH NORTHERN STREAM WAVE AS IT SHIFTS INTO THE MID-ATLANTIC FRIDAY NIGHT INTO SATURDAY MORNING. NAM/ECMWF INDICATE THE 1000-850MB 1300M THICKNESS LINE STRADDLING NORTH- CENTRAL WV AT THE ONSET FRIDAY NIGHT AND THEN SHIFTING NORTHWARD TO THE PITTSBURGH METRO BY DAWN ON SATURDAY. THUS, FORECAST IS FOR SNOW ACROSS THE AREA AT THE ONSET OF PRECIPITATION AFTER 00Z SATURDAY, AND CHANGE TO FZRA AND TO RAIN OVERNIGHT SOUTH OF THE MASON-DIXON LINE. NORTH OF THE MASON-DIXON LINE TO THE PITTSBURGH METRO, FORECAST IS FOR AN EXTENDED PERIOD OF A WINTRY MIX WITH ICE ACCUMULATIONS OF A TENTH TO TWO TENTHS OF AN INCH. NORTH OF THE PITTSBURGH METRO, PRECIP WILL BE SNOW FOR THE MAJORITY, WITH 3 TO 6 INCHES POSSIBLE FOR THE I-80 CORRIDOR. WITH COLD AIR HANGING ACROSS THE EASTERN RIDGES, A WINTER STORM WATCH HAS BEEN POSTED FOR GARRETT COUNTY AND THE WESTMO/FAYETTE RIDGES FOR THE POTENTIAL OF OVER A QUARTER INCH OF ICE. OTHERWISE, A TENTH TO TWO TENTHS OF ICE ARE NOT OUT OF THE QUESTION FOR AREAS BETWEEN MASON-DIXON LINE AND SOUTH OF THE I-80 CORRIDOR AND MAY LEAD TO AN ADVISORY. SATURDAY...WINTRY MIX OF PRECIPITATION WILL COME TO AN END DURING THE MORNING HOURS AS HIGH PRESSURE BEGINS TO BUILD IN FROM THE NORTHWEST. FOR TEMPS, WITH COLD AIR BUILT IN BEHIND THE FRONT ON FRIDAY, TEMPS WILL LIKELY REMAIN BELOW FREEZING THROUGHOUT THE DAY, WITH HIGHS RANGING FROM THE LOWER 20S ACROSS THE I-80 CORRIDOR TO THE LOWER 30S ACROSS PORTIONS OF EASTERN OHIO AND NORTH-CENTRAL WV. WARM AIR ADVECTION WILL TAKE PLACE SOUTH OF THE PITTSBURGH METRO FRIDAY NIGHT, WITH TEMPS RISING INTO THE MID 30S BY DAWN. TEMPS WILL REMAIN FAIRLY STEAD NORTH OF THE PITTSBURGH METRO IN THE MID TO UPPER 20S. TEMPS WILL CONTINUE TO MODERATE ON SATURDAY, CONSISTING OF A MAV/MET BLEND, RANGING FROM NEAR 30 ACROSS THE I-80 CORRIDOR TO THE LOWER 40S ACROSS NORTH-CENTRAL WV. && .LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/... PER RECENT SREF MODEL OUTPUT, EXPECT DRY CONDITIONS FOR SATURDAY NIGHT INTO SUNDAY EVENING. THEN BLEND OF RECENT SREF AND ECMWF MODEL OUTPUT SHOW A COLD FRONT, COMING EAST FRONT THE ROCKIES, WILL BRING SHOWERS LATE SUNDAY NIGHT INTO MONDAY NIGHT. THERE CAN BE A SUFFICIENT COLD POOL IN THE WAKE OF THE FRONTAL PASSAGE TO CAUSE A POSSIBLE CHANGE TO SNOW SHOWERS LATE MONDAY NIGHT AND TUESDAY. WITH THE UPPER LEVEL JETSTREAM MAINTAINING A WAVY ZONAL PATTERN, BLEND OF RECENT ECMWF AND GFS MODEL OUTPUT SHOWS A SECOND COLD FRONT, COMING EAST FROM THE ROCKIES, CAN PROVIDE SHOWERS WEDNESDAY NIGHT AND THURSDAY. THE PRECIPITATION TYPE THEN CAN BE RAIN OR SNOW AS SURFACE TEMPERATURES WILL BE MAINLY IN THE 30S. REGARDING OTHER ASPECTS OF THE TEMPERATURE FORECAST THIS PERIOD, ZONAL JETSTREAM PATTERN SHOULD MAINTAIN VALUES GENERALLY WARMER THAN NORMAL, WITH MONDAY AND THURSDAY HAVING VALUES MORE THAN 10 DEGREES ABOVE NORMAL. TUESDAY SHOULD BE THE COLDEST DAY, BUT EVEN THEN VALUES MAY BE NO COLDER THAN NORMAL. && .AVIATION /21Z THURSDAY THROUGH TUESDAY/... PER BLEND OF RECENT SURFACE AND RADAR DATA ALONG WITH NAM AND GFS LAMP MODEL OUTPUT, EXPECT A PREFRONTAL SNOW BAND, WITH IFR CONDITIONS, TO CONTINUE SOUTHEASTWARD THROUGH THE UPPER OHIO VALLEY THROUGH 04Z. PREFRONTAL SURFACE WINDS WILL BE FROM THE SOUTHWEST WITH GUSTS TO 25 KTS. POSTFRONTAL WINDS WILL BE NORTHWEST AND DECREASE TO 10 KTS BY LATE TONIGHT. DURING LATE TONIGHT AND FRIDAY MORNING, EXPECT POST-SYSTEM COLD POOL STRATOCUMULUS CEILINGS TO LIFT THROUGH MVFR LEVELS TO VFR LEVELS BY MIDDAY. OUTLOOK...FRIDAY NIGHT THROUGH TUESDAY... A WINTRY MIX WITH IFR RESTRICTIONS LATE FRIDAY NIGHT AND SATURDAY. VFR SUNDAY. RAIN SHOWERS WITH POSSIBLE RESTRICTIONS MONDAY AND MONDAY NIGHT, WITH A POSSIBLE CHANGE TO SNOW SHOWERS TUESDAY. && .PBZ WATCHES/WARNINGS/ADVISORIES... MD...WINTER STORM WATCH FROM FRIDAY EVENING THROUGH SATURDAY MORNING FOR MDZ001. OH...NONE. PA...WINTER WEATHER ADVISORY UNTIL MIDNIGHT EST TONIGHT FOR PAZ007>009-013>016-022-023. WINTER STORM WATCH FROM FRIDAY EVENING THROUGH SATURDAY MORNING FOR PAZ074-076. WV...NONE. && $$
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
134 PM EST THU JAN 19 2012 .SYNOPSIS... A FAST MOVING COLD FRONT WILL BRING A PERIOD OF ACCUMULATING SNOW THIS AFTERNOON INTO EARLY TONIGHT. LOW PRESSURE, MOVING NORTHEAST FROM TEXAS, WILL CROSS JUST SOUTH OF THE AREA, TO BRING A WINTRY MIX FOR FRIDAY NIGHT AND SATURDAY. && .NEAR TERM /THROUGH TONIGHT/... 18Z ENHANCED SHORT TERM FORECAST UPDATE HAS BEEN ISSUED TO INCREASE POPS EARLY NORTH OF THE I-80 CORRIDOR AS SNOW MOVES IN EARLY THIS AFTERNOON. THE LATEST RUC MID-LEVEL ANALYSIS INDICATES THE UPPER OHIO VALLEY IN A ZONAL FLOW AS A TROUGH MOVES ACROSS THE EASTERN GREAT LAKES. AT THE SURFACE, A 999MB LOW IS LOCATED NORTH OF MICHIGAN. A COLD FRONT EXTENDS SOUTH OF THIS FEATURE ACROSS MICHIGAN AND INTO NORTHWEST OHIO. AHEAD OF THE FRONT, AN AREA OF LIGHT SNOW IS PUSHING INTO EASTERN OHIO AND WESTERN PA. THE SNOW INCREASES IN INTENSITY CLOSER TO THE FRONT, WITH MODERATE SNOW REPORTED A FEW OBS UPSTREAM IN NORTHWEST OHIO. THIS AFTERNOON...THE COLD FRONT WILL QUICKLY SLIDE SOUTHEAST TOWARD THE AREA, WITH THE RUC/HRRR WIND SHIFT SUPPORTING THE FRONT REACHING A ZANESVILLE-NEW PHILADELPHIA-FRANKLIN LINE BY 00Z THIS EVENING. FORECAST CONSISTS OF A BLEND OF THE HRRR/NAM4KM, WITH LIGHT SNOW REACHING AREAS THE PITTSBURGH METRO AFTER 19Z WITH LIKELY POPS REACHING THE EASTERN RIDGES OF MD/WV BY 23Z. SNOW WILL INCREASE IN INTENSITY AT TIMES, REDUCING VISIBILITIES THIS EVENING. A FACTOR IN THE SNOWFALL ACCUMULATION AT LEAST INITIALLY WILL BE SURFACE TEMPS, WITH AREAS SOUTH OF I-70 WARMING INTO THE MID TO UPPER 30S. THIS WILL LIMIT SNOWFALL ACCUMULATION THERE INITIALLY. THUS FORECAST INTO THE EARLY EVENING IS FOR AROUND AN INCH NORTH OF I-70 AND FOR A HALF OF AN INCH OR LESS SOUTHWARD. FOR TEMPS, FORECAST IS A FEW DEGREES WARMER THAN A LAMP/HRRR BLEND, WITH HIGHS RANGING FROM THE UPPER 30S ACROSS NORTH-CENTRAL WV TO NEAR 30 ALONG THE I-80 CORRIDOR. TONIGHT...THE COLD FRONT WILL QUICKLY SLIDE SOUTHEAST ACROSS THE UPPER OHIO VALLEY, PUSHING SOUTHEAST OF THE RIDGES BY 03Z FRI. THE BEST CHANCE FOR SNOW ACCUMULATION AND POTENTIALLY HAZARDOUS TRAVEL WILL BE AROUND SUNSET THROUGH MIDNIGHT AS SNOW PUSHES ACROSS THE AREA. SNOW WILL BEGIN TO TAPER OFF BEHIND THE FRONT WITH JUST A FEW LINGERING SNOW SHOWERS ALONG THE I-80 CORRIDOR AND EASTERN RIDGES BY DAWN. MOSTLY AROUND AN ADDITIONAL INCH OF SNOWFALL WILL BE POSSIBLE TONIGHT, WITH 1 TO 3 POSSIBLE IN LOCALIZED AREAS AND THE EASTERN RIDGES. STRONG COLD AIR ADVECTION IN THE WAKE OF THE FRONT WILL ALLOW FOR LOWS RANGING FROM NEAR 20 ACROSS NORTH- CENTRAL WV TO THE MID TO UPPER TEENS ELSEWHERE. TOTAL SNOWFALL FOR THIS AFTERNOON THROUGH TONIGHT WILL GENERALLY BE 1 TO 2 INCHES ACROSS MUCH OF THE AREA. LOCALIZED AREAS OF UP TO 3 INCHES WILL BE POSSIBLE NORTH OF THE PITTSBURGH METRO AND ACROSS THE EASTERN RIDGES WITH COOLER TEMPS AT THE ONSET OF THE SNOW. IN ADDITION, MOST LOWLAND AREAS SOUTH OF I-70 WILL SEE LESS AN INCH. ALTHOUGH SNOW AMOUNTS FORECAST ARE MOSTLY SUB-ADVISORY AMOUNTS, WILL CONTINUE THE WINTER WEATHER ADVISORY FOR AREAS NORTH OF PITTSBURGH DUE TO TIMING OF THE SNOW IMPACTING THE EVENING COMMUTE. && .SHORT TERM /FRIDAY THROUGH SATURDAY/... MUCH OF FRIDAY LOOKS TO BE DRY...BUT NEXT SHORTWAVE IN PROGRESSIVE FLOW IS TIMED TO GENERATE MORE PRECIP BY LATE DAY. LATEST DETERMINISTIC MODELS DIFFER GREATLY IN TIMING...TEMPERATURE PROFILES...AND THE RESULTING PRECIP TYPES AND AMOUNTS. FORECAST IS THUS BASED ON A COMBO OF PERSISTENCE AND NAM/GFS BLEND AND FEATURES A WINTRY MIX FOR FRIDAY NIGHT AND SATURDAY. BEST CHANCE OF ACCUMULATING SNOW APPEARS FOR NOW TO BE OVER AREAS NORTH OF PITTSBURGH...BUT ICE ACCUMULATION MAY BE A DEVELOPING HAZARD FOR THE REMAINDER OF THE AREA. WILL ISSUE A HAZARDOUS WEATHER OUTLOOK FOR THESE POTENTIALS. && .LONG TERM /SATURDAY NIGHT THROUGH THURSDAY/... SURFACE RIDGE WILL BUILD IN BEHIND A DEPARTING SYSTEM AND PROVIDE DRY WEATHER LATE SATURDAY NIGHT INTO SUNDAY. AN APPROACHING SHORTWAVE TROUGH WILL THEN PUSH A SURFACE LOW ACROSS THE GREAT LAKES. PERIODS OF SHOWERS WILL ACCOMPANY THE ASSOCIATED COLD FRONT MONDAY...WITH SCATTERED SHOWERS EXPECTED TO CONTINUE INTO TUESDAY AS MOISTURE WRAPS BEHIND THE LOW. DRIER CONDITIONS SHOULD RETURN BY WEDNESDAY AS A SURFACE HIGH MOVES EASTWARD INTO THE OHIO VALLEY. STAYED CLOSE TO HPC GUIDANCE WITH TEMPERATURES REMAINING WELL ABOVE NORMAL THROUGH THE EXTENDED PERIOD. && .AVIATION /18Z THURSDAY THROUGH TUESDAY/... PER BLEND OF RECENT SURFACE AND RADAR DATA ALONG WITH NAM AND GFS LAMP MODEL OUTPUT, EXPECT A PREFRONTAL SNOW BAND, WITH IFR CONDITIONS, TO MOVE SOUTHEASTWARD THROUGH THE UPPER OHIO VALLEY THROUGH 04Z. PREFRONTAL SURFACE WINDS WILL BE FROM THE SOUTHWEST WITH GUSTS TO 25 KTS. POSTFRONTAL WINDS WILL BE NORTHWEST AND DECREASE TO 10 KTS BY LATE TONIGHT. DURING LATE TONIGHT AND FRIDAY MORNING, EXPECT POST-SYSTEM COLD POOL STRATOCUMULUS CEILINGS TO LIFT THROUGH MVFR LEVELS TO VFR LEVELS BY MIDDAY. OUTLOOK...FRIDAY NIGHT THROUGH MONDAY... A WINTRY MIX WITH RESTRICTIONS LATE FRIDAY NIGHT AND SATURDAY. VFR SUNDAY. RAIN SHOWERS WITH RESTRICTIONS MONDAY. && .PBZ WATCHES/WARNINGS/ADVISORIES... MD...NONE. OH...NONE. PA...WINTER WEATHER ADVISORY UNTIL MIDNIGHT EST TONIGHT FOR PAZ007>009-013>016-022-023. WV...NONE. && $$
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
1250 PM EST THU JAN 19 2012 .SYNOPSIS... A FAST MOVING COLD FRONT WILL BRING A PERIOD OF ACCUMULATING SNOW THIS AFTERNOON INTO EARLY TONIGHT. LOW PRESSURE, MOVING NORTHEAST FROM TEXAS, WILL CROSS JUST SOUTH OF THE AREA, TO BRING A WINTRY MIX FOR FRIDAY NIGHT AND SATURDAY. && .NEAR TERM /THROUGH TONIGHT/... LATE MORNING ENHANCED SHORT TERM FORECAST UPDATE HAD BEEN ISSUED TO SLOW THE ONSET OF SNOW BY A FEW HOURS THIS AFTERNOON. OTHERWISE, LITTLE CHANGE TO THE GOING FORECAST. THE LATEST RUC MID-LEVEL ANALYSIS INDICATES THE UPPER OHIO VALLEY IN A ZONAL FLOW AS A TROUGH MOVES ACROSS THE GREAT LAKES. AT THE SURFACE, A 1000MB LOW IS LOCATED NORTH OF MICHIGAN. A COLD FRONT EXTENDS SOUTHWEST OF THIS FEATURE ACROSS MICHIGAN AND INTO INDIANA. AHEAD OF THE FRONT, AN AREA OF LIGHT SNOW IS PUSHING INTO THE NORTHWEST HALF OF OHIO. THE SNOW INCREASES IN INTENSITY CLOSER TO THE FRONT, WITH MODERATE SNOW REPORTED WITH SEVERAL OBS UPSTREAM IN INDIANA. THIS AFTERNOON...THE COLD FRONT WILL QUICKLY SLIDE SOUTHEAST TOWARD THE AREA, WITH THE RUC/HRRR WIND SHIFT SUPPORTING THE FRONT REACHING A ZANESVILLE-NEW PHILADELPHIA-FRANKLIN LINE BY 00Z THIS EVENING. FORECAST CONSISTS OF A BLEND OF THE HRRR/NAM4KM, WITH LIGHT SNOW REACHING AREAS NORTH AND WEST OF PITTSBURGH BY 19Z WITH LIKELY POPS REACHING THE EASTERN RIDGES OF MD/WV BY 23Z. SNOW WILL INCREASE IN INTENSITY AT TIMES, REDUCING VISIBILITIES THIS EVENING. A FACTOR IN THE SNOWFALL ACCUMULATION AT LEAST INITIALLY WILL BE SURFACE TEMPS, WITH AREAS SOUTH OF I-70 WARMING INTO THE MID TO UPPER 30S. THIS WILL LIMIT SNOWFALL ACCUMULATION THERE INITIALLY. THUS FORECAST INTO THE EARLY EVENING IS FOR AROUND AN INCH NORTH OF I-70 AND FOR A HALF OF AN INCH OR LESS SOUTHWARD. FOR TEMPS, FORECAST IS A FEW DEGREES WARMER THAN A LAMP/HRRR BLEND, WITH HIGHS RANGING FROM THE UPPER 30S ACROSS NORTH-CENTRAL WV TO NEAR 30 ALONG THE I-80 CORRIDOR. TONIGHT...THE COLD FRONT WILL QUICKLY SLIDE SOUTHEAST ACROSS THE UPPER OHIO VALLEY, PUSHING SOUTHEAST OF THE RIDGES BY 03Z FRI. THE BEST CHANCE FOR SNOW ACCUMULATION AND POTENTIALLY HAZARDOUS TRAVEL WILL BE AFTER SUNSET THROUGH MIDNIGHT AS SNOW PUSHES ACROSS THE AREA. SNOW WILL BEGIN TO TAPER OFF BEHIND THE FRONT WITH JUST A FEW LINGERING SNOW SHOWERS ALONG THE I-80 CORRIDOR AND EASTERN RIDGES BY DAWN. MOSTLY AROUND AN ADDITIONAL INCH OF SNOWFALL WILL BE POSSIBLE TONIGHT, WITH 1 TO 3 POSSIBLE IN LOCALIZED AREAS AND THE EASTERN RIDGES. STRONG COLD AIR ADVECTION IN THE WAKE OF THE FRONT WILL ALLOW FOR LOWS RANGING FROM NEAR 20 ACROSS NORTH-CENTRAL WV TO THE MID TO UPPER TEENS ELSEWHERE. TOTAL SNOWFALL FOR THIS AFTERNOON THROUGH TONIGHT WILL GENERALLY BE 1 TO 2 INCHES ACROSS MUCH OF THE AREA. LOCALIZED AREAS OF UP TO 3 INCHES WILL BE POSSIBLE NORTH OF THE PITTSBURGH METRO AND ACROSS THE EASTERN RIDGES WITH COOLER TEMPS AT THE ONSET OF THE SNOW. IN ADDITION, AREAS SOUTH OF I-70 WILL SEE AROUND AN INCH. ALTHOUGH SNOW AMOUNTS FORECAST ARE MOSTLY SUB-ADVISORY AMOUNTS, WILL CONTINUE THE WINTER WEATHER ADVISORY FOR AREAS NORTH OF PITTSBURGH DUE TO TIMING OF THE SNOW IMPACTING THE EVENING COMMUTE. && .SHORT TERM /FRIDAY THROUGH SATURDAY/... MUCH OF FRIDAY LOOKS TO BE DRY...BUT NEXT SHORTWAVE IN PROGRESSIVE FLOW IS TIMED TO GENERATE MORE PRECIP BY LATE DAY. LATEST DETERMINISTIC MODELS DIFFER GREATLY IN TIMING...TEMPERATURE PROFILES...AND THE RESULTING PRECIP TYPES AND AMOUNTS. FORECAST IS THUS BASED ON A COMBO OF PERSISTENCE AND NAM/GFS BLEND AND FEATURES A WINTRY MIX FOR FRIDAY NIGHT AND SATURDAY. BEST CHANCE OF ACCUMULATING SNOW APPEARS FOR NOW TO BE OVER AREAS NORTH OF PITTSBURGH...BUT ICE ACCUMULATION MAY BE A DEVELOPING HAZARD FOR THE REMAINDER OF THE AREA. WILL ISSUE A HAZARDOUS WEATHER OUTLOOK FOR THESE POTENTIALS. && .LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/... SURFACE RIDGE WILL BUILD IN BEHIND A DEPARTING SYSTEM AND PROVIDE DRY WEATHER LATE SATURDAY NIGHT INTO SUNDAY. AN APPROACHING SHORTWAVE TROUGH WILL THEN PUSH A SURFACE LOW ACROSS THE GREAT LAKES. PERIODS OF SHOWERS WILL ACCOMPANY THE ASSOCIATED COLD FRONT MONDAY...WITH SCATTERED SHOWERS EXPECTED TO CONTINUE INTO TUESDAY AS MOISTURE WRAPS BEHIND THE LOW. DRIER CONDITIONS SHOULD RETURN BY WEDNESDAY AS A SURFACE HIGH MOVES EASTWARD INTO THE OHIO VALLEY. STAYED CLOSE TO HPC GUIDANCE WITH TEMPERATURES REMAINING WELL ABOVE NORMAL THROUGH THE EXTENDED PERIOD. && .AVIATION /18Z THURSDAY THROUGH TUESDAY/... PER BLEND OF RECENT SURFACE AND RADAR DATA ALONG WITH NAM AND GFS LAMP MODEL OUTPUT, EXPECT A PREFRONTAL SNOW BAND, WITH IFR CONDITIONS, TO MOVE SOUTHEASTWARD THROUGH THE UPPER OHIO VALLEY THROUGH 04Z. PREFRONTAL SURFACE WINDS WILL BE FROM THE SOUTHWEST WITH GUSTS TO 25 KTS. POSTFRONTAL WINDS WILL BE NORTHWEST AND DECREASE TO 10 KTS BY LATE TONIGHT. DURING LATE TONIGHT AND FRIDAY MORNING, EXPECT POST-SYSTEM COLD POOL STRATOCUMULUS CEILINGS TO LIFT THROUGH MVFR LEVELS TO VFR LEVELS BY MIDDAY. OUTLOOK...FRIDAY NIGHT THROUGH MONDAY... A WINTRY MIX WITH RESTRICTIONS LATE FRIDAY NIGHT AND SATURDAY. VFR SUNDAY. RAIN SHOWERS WITH RESTRICTIONS MONDAY. && .PBZ WATCHES/WARNINGS/ADVISORIES... MD...NONE. OH...NONE. PA...WINTER WEATHER ADVISORY UNTIL MIDNIGHT EST TONIGHT FOR PAZ007>009-013>016-022-023. WV...NONE. && $$
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
1139 AM EST THU JAN 19 2012 .SYNOPSIS... A FAST MOVING COLD FRONT WILL BRING A PERIOD OF ACCUMULATING SNOW THIS AFTERNOON INTO EARLY TONIGHT. LOW PRESSURE, MOVING NORTHEAST FROM TEXAS, WILL CROSS JUST SOUTH OF THE AREA, TO BRING A WINTRY MIX FOR FRIDAY NIGHT AND SATURDAY. && .NEAR TERM /THROUGH TONIGHT/... LATE MORNING ENHANCED SHORT TERM FORECAST UPDATE HAD BEEN ISSUED TO SLOW THE ONSET OF SNOW BY A FEW HOURS THIS AFTERNOON. OTHERWISE, LITTLE CHANGE TO THE GOING FORECAST. THE LATEST RUC MID-LEVEL ANALYSIS INDICATES THE UPPER OHIO VALLEY IN A ZONAL FLOW AS A TROUGH MOVES ACROSS THE GREAT LAKES. AT THE SURFACE, A 1000MB LOW IS LOCATED NORTH OF MICHIGAN. A COLD FRONT EXTENDS SOUTHWEST OF THIS FEATURE ACROSS MICHIGAN AND INTO INDIANA. AHEAD OF THE FRONT, AN AREA OF LIGHT SNOW IS PUSHING INTO THE NORTHWEST HALF OF OHIO. THE SNOW INCREASES IN INTENSITY CLOSER TO THE FRONT, WITH MODERATE SNOW REPORTED WITH SEVERAL OBS UPSTREAM IN INDIANA. THIS AFTERNOON...THE COLD FRONT WILL QUICKLY SLIDE SOUTHEAST TOWARD THE AREA, WITH THE RUC/HRRR WIND SHIFT SUPPORTING THE FRONT REACHING A ZANESVILLE-NEW PHILADELPHIA-FRANKLIN LINE BY 00Z THIS EVENING. FORECAST CONSISTS OF A BLEND OF THE HRRR/NAM4KM, WITH LIGHT SNOW REACHING AREAS NORTH AND WEST OF PITTSBURGH BY 19Z WITH LIKELY POPS REACHING THE EASTERN RIDGES OF MD/WV BY 23Z. SNOW WILL INCREASE IN INTENSITY AT TIMES, REDUCING VISIBILITIES THIS EVENING. A FACTOR IN THE SNOWFALL ACCUMULATION AT LEAST INITIALLY WILL BE SURFACE TEMPS, WITH AREAS SOUTH OF I-70 WARMING INTO THE MID TO UPPER 30S. THIS WILL LIMIT SNOWFALL ACCUMULATION THERE INITIALLY. THUS FORECAST INTO THE EARLY EVENING IS FOR AROUND AN INCH NORTH OF I-70 AND FOR A HALF OF AN INCH OR LESS SOUTHWARD. FOR TEMPS, FORECAST IS A FEW DEGREES WARMER THAN A LAMP/HRRR BLEND, WITH HIGHS RANGING FROM THE UPPER 30S ACROSS NORTH-CENTRAL WV TO NEAR 30 ALONG THE I-80 CORRIDOR. TONIGHT...THE COLD FRONT WILL QUICKLY SLIDE SOUTHEAST ACROSS THE UPPER OHIO VALLEY, PUSHING SOUTHEAST OF THE RIDGES BY 03Z FRI. THE BEST CHANCE FOR SNOW ACCUMULATION AND POTENTIALLY HAZARDOUS TRAVEL WILL BE AFTER SUNSET THROUGH MIDNIGHT AS SNOW PUSHES ACROSS THE AREA. SNOW WILL BEGIN TO TAPER OFF BEHIND THE FRONT WITH JUST A FEW LINGERING SNOW SHOWERS ALONG THE I-80 CORRIDOR AND EASTERN RIDGES BY DAWN. MOSTLY AROUND AN ADDITIONAL INCH OF SNOWFALL WILL BE POSSIBLE TONIGHT, WITH 1 TO 3 POSSIBLE IN LOCALIZED AREAS AND THE EASTERN RIDGES. STRONG COLD AIR ADVECTION IN THE WAKE OF THE FRONT WILL ALLOW FOR LOWS RANGING FROM NEAR 20 ACROSS NORTH-CENTRAL WV TO THE MID TO UPPER TEENS ELSEWHERE. TOTAL SNOWFALL FOR THIS AFTERNOON THROUGH TONIGHT WILL GENERALLY BE 1 TO 2 INCHES ACROSS MUCH OF THE AREA. LOCALIZED AREAS OF UP TO 3 INCHES WILL BE POSSIBLE NORTH OF THE PITTSBURGH METRO AND ACROSS THE EASTERN RIDGES WITH COOLER TEMPS AT THE ONSET OF THE SNOW. IN ADDITION, AREAS SOUTH OF I-70 WILL SEE AROUND AN INCH. ALTHOUGH SNOW AMOUNTS FORECAST ARE MOSTLY SUB-ADVISORY AMOUNTS, WILL CONTINUE THE WINTER WEATHER ADVISORY FOR AREAS NORTH OF PITTSBURGH DUE TO TIMING OF THE SNOW IMPACTING THE EVENING COMMUTE. && .SHORT TERM /FRIDAY THROUGH SATURDAY/... MUCH OF FRIDAY LOOKS TO BE DRY...BUT NEXT SHORTWAVE IN PROGRESSIVE FLOW IS TIMED TO GENERATE MORE PRECIP BY LATE DAY. LATEST DETERMINISTIC MODELS DIFFER GREATLY IN TIMING...TEMPERATURE PROFILES...AND THE RESULTING PRECIP TYPES AND AMOUNTS. FORECAST IS THUS BASED ON A COMBO OF PERSISTENCE AND NAM/GFS BLEND AND FEATURES A WINTRY MIX FOR FRIDAY NIGHT AND SATURDAY. BEST CHANCE OF ACCUMULATING SNOW APPEARS FOR NOW TO BE OVER AREAS NORTH OF PITTSBURGH...BUT ICE ACCUMULATION MAY BE A DEVELOPING HAZARD FOR THE REMAINDER OF THE AREA. WILL ISSUE A HAZARDOUS WEATHER OUTLOOK FOR THESE POTENTIALS. && .LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/... SURFACE RIDGE WILL BUILD IN BEHIND A DEPARTING SYSTEM AND PROVIDE DRY WEATHER LATE SATURDAY NIGHT INTO SUNDAY. AN APPROACHING SHORTWAVE TROUGH WILL THEN PUSH A SURFACE LOW ACROSS THE GREAT LAKES. PERIODS OF SHOWERS WILL ACCOMPANY THE ASSOCIATED COLD FRONT MONDAY...WITH SCATTERED SHOWERS EXPECTED TO CONTINUE INTO TUESDAY AS MOISTURE WRAPS BEHIND THE LOW. DRIER CONDITIONS SHOULD RETURN BY WEDNESDAY AS A SURFACE HIGH MOVES EASTWARD INTO THE OHIO VALLEY. STAYED CLOSE TO HPC GUIDANCE WITH TEMPERATURES REMAINING WELL ABOVE NORMAL THROUGH THE EXTENDED PERIOD. && .AVIATION /16Z THURSDAY THROUGH MONDAY/... VFR FORECAST INTO THE AFTERNOON. AFTER DAWN, THERE WILL BE IN AN INCREASE IN MID DECK CLOUD COVER AS WELL AS STRENGTHENING SW SFC WINDS, WITH SOME GUSTS TO 20 KTS BY MIDDAY. COLD FRONT WILL REACH THE WESTERN EDGE OF THE AREA AROUND 20Z. MVFR TO IFR RESTRICTIONS WITH SNOW AND LOW CLOUDS EXPECTED AT ALL PORTS DURING THE AFTERNOON AND EVENING HOURS. OUTLOOK...TONIGHT NIGHT THROUGH MONDAY... RESTRICTIONS WITH SNOW AND LOW CLOUDS WILL CONTINUE THROUGH THIS EVENING. VIS SHOULD QUICKLY IMPROVE AFTER 06Z AS AREA OF SNOW SHOWERS MOVES SOUTHEAST. VFR CONDITIONS WILL BRIEFLY RETURN FRIDAY AS A SURFACE HIGH SLIDES ACROSS THE REGION. A SYSTEM TRACKING SOUTH OF THE AREA WILL BRING A WINTRY MIX WITH RESTRICTIONS FRIDAY NIGHT AND SATURDAY. AFTER A PERIOD OF VFR WEATHER SUNDAY, AN APPROACHING FRONT IS PROGGED TO SPREAD SCATTERED RAIN SHOWERS AND RESTRICTIONS ACROSS THE TERMINALS MONDAY. && .PBZ WATCHES/WARNINGS/ADVISORIES... MD...NONE. OH...NONE. PA...WINTER WEATHER ADVISORY UNTIL MIDNIGHT EST TONIGHT FOR PAZ007>009-013>016-022-023. WV...NONE. && $$
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
819 AM EST THU JAN 19 2012 .SYNOPSIS... A FAST MOVING COLD FRONT WILL BRING A PERIOD OF ACCUMULATING SNOW THIS AFTERNOON INTO EARLY TONIGHT. LOW PRESSURE, COMING NORTHEAST FROM TEXAS, WILL CROSS JUST SOUTH OF THE AREA, TO BRING A WINTRY MIX FOR FRIDAY NIGHT AND SATURDAY. && .NEAR TERM /THROUGH TONIGHT/... RECENT HRRR MODEL OUTPUT CONTINUES TO SHOW FRONTAL BAND OF SNOW WILL BEGIN SPREADING SOUTHEASTWARD ACROSS THE UPPER OHIO VALLEY DURING MIDDAY. TEMPERATURES NORTH WILL LIKELY NOT GET WARMER THAN FREEZING BEFOREHAND, WHILE TEMPERATURES SOUTH WILL. ONCE PRECIPITATION BEGINS, ALL TEMPERATURES WILL DROP TO BELOW FREEZING, HENCE THIS SHOULD BE AN ALL SNOW EVENT. CONTINUE TO EXPECT SNOW AMOUNTS FOR MOST PLACES TO BE AROUND 2 INCHES, POSSIBLY MORE NORTH. WILL MAINTAIN CURRENT WINTER WEATHER ADVISORIES NORTH, AND MAY CONSIDER EXPANSION SOUTH, DUE TO POTENTIAL OF HAZARDOUS IMPACTS WITH TEMPERATURES NEAR FREEZING AND SNOWFALL CONTINUING PAST THE EVENING COMMUTER RUSH. HIGH PRESSURE WILL BUILD IN THE WAKE OF THE FRONT TONIGHT AND GRADUALLY END THE SNOW. TEMPERATURES WERE FORECAST A FEW DEGREES UNDER THE SEASONAL AVERAGES USING TWEAKED NAMDNG5 NMBRS. && .SHORT TERM /FRIDAY THROUGH SATURDAY/... MUCH OF FRIDAY LOOKS TO BE DRY...BUT NEXT SHORTWAVE IN PROGRESSIVE FLOW IS TIMED TO GENERATE MORE PRECIP BY LATE DAY. LATEST DETERMINISTIC MODELS DIFFER GREATLY IN TIMING...TEMPERATURE PROFILES...AND THE RESULTING PRECIP TYPES AND AMOUNTS. FORECAST IS THUS BASED ON A COMBO OF PERSISTENCE AND NAM/GFS BLEND AND FEATURES A WINTRY MIX FOR FRIDAY NIGHT AND SATURDAY. BEST CHANCE OF ACCUMULATING SNOW APPEARS FOR NOW TO BE OVER AREAS NORTH OF PITTSBURGH...BUT ICE ACCUMULATION MAY BE A DEVELOPING HAZARD FOR THE REMAINDER OF THE AREA. WILL ISSUE A HAZARDOUS WEATHER OUTLOOK FOR THESE POTENTIALS. && .LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/... SURFACE RIDGE WILL BUILD IN BEHIND A DEPARTING SYSTEM AND PROVIDE DRY WEATHER LATE SATURDAY NIGHT INTO SUNDAY. AN APPROACHING SHORTWAVE TROUGH WILL THEN PUSH A SURFACE LOW ACROSS THE GREAT LAKES. PERIODS OF SHOWERS WILL ACCOMPANY THE ASSOCIATED COLD FRONT MONDAY...WITH SCATTERED SHOWERS EXPECTED TO CONTINUE INTO TUESDAY AS MOISTURE WRAPS BEHIND THE LOW. DRIER CONDITIONS SHOULD RETURN BY WEDNESDAY AS A SURFACE HIGH MOVES EASTWARD INTO THE OHIO VALLEY. STAYED CLOSE TO HPC GUIDANCE WITH TEMPERATURES REMAINING WELL ABOVE NORMAL THROUGH THE EXTENDED PERIOD. && .AVIATION /13Z THURSDAY THROUGH MONDAY/... VFR FORECAST INTO THE AFTERNOON. AFTER DAWN, THERE WILL BE IN AN INCREASE IN MID DECK CLOUD COVER AS WELL AS STRENGTHENING SW SFC WINDS, WITH SOME GUSTS TO 20 KTS BY MIDDAY. COLD FRONT WILL REACH THE WESTERN EDGE OF THE AREA AROUND 20Z. MVFR TO IFR RESTRICTIONS WITH SNOW AND LOW CLOUDS EXPECTED AT ALL PORTS DURING THE AFTERNOON AND EVENING HOURS. OUTLOOK...TONIGHT NIGHT THROUGH MONDAY... RESTRICTIONS WITH SNOW AND LOW CLOUDS WILL CONTINUE THROUGH THIS EVENING. VIS SHOULD QUICKLY IMPROVE AFTER 06Z AS AREA OF SNOW SHOWERS MOVES SOUTHEAST. VFR CONDITIONS WILL BRIEFLY RETURN FRIDAY AS A SURFACE HIGH SLIDES ACROSS THE REGION. A SYSTEM TRACKING SOUTH OF THE AREA WILL BRING A WINTRY MIX WITH RESTRICTIONS FRIDAY NIGHT AND SATURDAY. AFTER A PERIOD OF VFR WEATHER SUNDAY, AN APPROACHING FRONT IS PROGGED TO SPREAD SCATTERED RAIN SHOWERS AND RESTRICTIONS ACROSS THE TERMINALS MONDAY. && .PBZ WATCHES/WARNINGS/ADVISORIES... MD...NONE. OH...NONE. PA...WINTER WEATHER ADVISORY FROM NOON TODAY TO MIDNIGHT EST TONIGHT FOR PAZ007>009-013>016-022-023. WV...NONE. && $$
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
808 AM EST THU JAN 19 2012 .SYNOPSIS... ACCUMULATING SNOW SHOWERS CAN BE EXPECTED TODAY AS A FAST MOVING COLD FRONT CROSSES THE UPPER OHIO VALLEY REGION. LOW PRESSURE, COMING NORTHEAST FROM TEXAS, WILL CROSS JUST SOUTH OF THE AREA, TO BRING A WINTRY MIX FOR FRIDAY NIGHT AND SATURDAY. && .NEAR TERM /THROUGH TONIGHT/... RECENT HRRR MODEL OUTPUT CONTINUES TO SHOW FRONTAL BAND OF SNOW SHOWERS WILL BEGIN SPREADING SOUTHEASTWARD ACROSS THE UPPER OHIO VALLEY DURING MIDDAY. TEMPERATURES NORTH WILL LIKELY NOT GET WARMER THAN FREEZING, WHILE TEMPERATURES SOUTH WILL. ONCE PRECIPITATION BEGINS, ALL TEMPERATURES WILL DROP TO BELOW FREEZING, HENCE THIS SHOULD BE AN ALL SNOW EVENT. CONTINUE TO EXPECT SNOW AMOUNTS FOR MOST PLACES TO BE AROUND 2 INCHES, POSSIBLY MORE NORTH. WILL MAINTAIN CURRENT WINTER WEATHER ADVISORIES NORTH, AND MAY CONSIDER EXPANSION SOUTH, CONTINUING POTENTIAL OF HAZARDOUS IMPACTS WITH TEMPERATURES NEAR FREEZING AND SNOWFALL CONTINUING PAST THE EVENING COMMUTER RUSH. HIGH PRESSURE WILL BUILD IN THE WAKE OF THE FRONT TONIGHT AND GRADUALLY END THE SNOW. TEMPERATURES WERE FORECAST A FEW DEGREES UNDER THE SEASONAL AVERAGES USING TWEAKED NAMDNG5 NMBRS. && .SHORT TERM /FRIDAY THROUGH SATURDAY/... MUCH OF FRIDAY LOOKS TO BE DRY...BUT NEXT SHORTWAVE IN PROGRESSIVE FLOW IS TIMED TO GENERATE MORE PRECIP BY LATE DAY. LATEST DETERMINISTIC MODELS DIFFER GREATLY IN TIMING...TEMPERATURE PROFILES...AND THE RESULTING PRECIP TYPES AND AMOUNTS. FORECAST IS THUS BASED ON A COMBO OF PERSISTENCE AND NAM/GFS BLEND AND FEATURES A WINTRY MIX FOR FRIDAY NIGHT AND SATURDAY. BEST CHANCE OF ACCUMULATING SNOW APPEARS FOR NOW TO BE OVER AREAS NORTH OF PITTSBURGH...BUT ICE ACCUMULATION MAY BE A DEVELOPING HAZARD FOR THE REMAINDER OF THE AREA. WILL ISSUE A HAZARDOUS WEATHER OUTLOOK FOR THESE POTENTIALS. && .LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/... SURFACE RIDGE WILL BUILD IN BEHIND A DEPARTING SYSTEM AND PROVIDE DRY WEATHER LATE SATURDAY NIGHT INTO SUNDAY. AN APPROACHING SHORTWAVE TROUGH WILL THEN PUSH A SURFACE LOW ACROSS THE GREAT LAKES. PERIODS OF SHOWERS WILL ACCOMPANY THE ASSOCIATED COLD FRONT MONDAY...WITH SCATTERED SHOWERS EXPECTED TO CONTINUE INTO TUESDAY AS MOISTURE WRAPS BEHIND THE LOW. DRIER CONDITIONS SHOULD RETURN BY WEDNESDAY AS A SURFACE HIGH MOVES EASTWARD INTO THE OHIO VALLEY. STAYED CLOSE TO HPC GUIDANCE WITH TEMPERATURES REMAINING WELL ABOVE NORMAL THROUGH THE EXTENDED PERIOD. && .AVIATION /13Z THURSDAY THROUGH MONDAY/... VFR FORECAST INTO THE AFTERNOON. AFTER DAWN, THERE WILL BE IN AN INCREASE IN MID DECK CLOUD COVER AS WELL AS STRENGTHENING SW SFC WINDS, WITH SOME GUSTS TO 20 KTS BY MIDDAY. COLD FRONT WILL REACH THE WESTERN EDGE OF THE AREA AROUND 20Z. MVFR TO IFR RESTRICTIONS WITH SNOW SHOWERS AND LOW CLOUDS EXPECTED AT ALL PORTS DURING THE AFTERNOON AND EVENING HOURS. OUTLOOK...TONIGHT NIGHT THROUGH MONDAY... RESTRICTIONS WITH SNOW AND LOW CLOUDS WILL CONTINUE THROUGH THIS EVENING. VIS SHOULD QUICKLY IMPROVE AFTER 06Z AS AREA OF SNOW SHOWERS MOVES SOUTHEAST. VFR CONDITIONS WILL BRIEFLY RETURN FRIDAY AS A SURFACE HIGH SLIDES ACROSS THE REGION. A SYSTEM TRACKING SOUTH OF THE AREA WILL BRING A WINTRY MIX WITH RESTRICTIONS FRIDAY NIGHT AND SATURDAY. AFTER A PERIOD OF VFR WEATHER SUNDAY, AN APPROACHING FRONT IS PROGGED TO SPREAD SCATTERED RAIN SHOWERS AND RESTRICTIONS ACROSS THE TERMINALS MONDAY. && .PBZ WATCHES/WARNINGS/ADVISORIES... MD...NONE. OH...NONE. PA...WINTER WEATHER ADVISORY FROM NOON TODAY TO MIDNIGHT EST TONIGHT FOR PAZ007>009-013>016-022-023. WV...NONE. && $$
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
1226 AM EST THU JAN 19 2012 UPDATED AVIATION DISCUSSION FOR 06Z TAFS .SYNOPSIS... 12Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW WEAK SHRTWV RDGING IMPACTING THE UPR GRT LKS WITHIN LO AMPLITUDE TROFFING OVER CENTRAL NAMERICA TO THE S OF CLOSED LO OVER HUDSON BAY. AS OF EARLY THIS AFTN...THE SUBSIDENCE ASSOCIATED WITH THE SHRTWV RDG HAS ENDED PCPN EVERYWHERE EXCEPT OVER THE N HALF OF THE KEWEENAW PENINSULA...WHERE A LO PRES TROF LINGERS TO THE N OF SFC HI PRES IN THE OH RIVER VALLEY. BUT AS THE FLOW CONTINUES TO BACK TO THE SW BTWN THE DEPARTING HI TO THE SE AND ANOTHER SHRTWV MOVING E THRU THE NRN PLAINS...THESE SHSN ARE TENDING TO DRIFT NEWD INTO LK SUP. THE DISTURBANCE TO THE W IS A POTENT ONE WITH SUPPORTING H5/H3 JET MAX AND WIND SPEEDS OF 100KT/150KT DIGGING ESEWD THRU THE NW PLAINS. HOWEVER...SINCE UPSTREAM AIRMASS IS FAIRLY DRY...THE BULK OF THE PCPN IS FALLING TO THE N OF WARM FNT AND ON THE COLD SIDE OF COLD FNT ATTENDANT TO SFC LO IN WCNTRL MN. GUSTY NW WINDS UP TO 35-40KTS ARE DRIVING VERY COLD AIR SEWD INTO THE NRN PLAINS BEHIND THIS LO AND AHEAD OF VIGOROUS PRES RISE CENTER IN THE DAKOTAS. THE 12Z H85 TEMP AT GREAT FALLS MT WAS -31C. && .SHORT TERM DISCUSSION /TNGT AND THU/... TNGT...SHRTWV TO THE W IS FCST TO SLIDE ESEWD THRU NRN WI AND INTO NRN LWR MI BY 12Z THU WHILE SFC LO CENTER SHIFTS ENEWD ACRS THE KEWEENAW AND INTO ERN LK SUP BY 12Z THU. STRONG SLY FLOW OF H85 TEMPS ARND -12C OFF THE 4C WARM WATERS OF LK MI AHEAD OF THIS FEATURE INDICATE THERE WL BE ENUF INSTABILITY TO GENERATE LES... WITH SOME ENHANCEMENT AS DEEP LYR QVECTOR CNVGC/MSTR ASSOCIATED WITH APRCHG SHRTWV ARRIVE OVHD. 12Z NAM/CNDN MODELS SHOW QPF OF 0.20-0.30 INCH NEAR ERY. CONSIDERING FVRBL OMEGA PROFILE WITHIN DGZ...EXPECT HI SN/WATER RATIO ARND 25:1 AND UP TO 6 INCHES OF SN E OF ERY. THE WINDOW OF OPPORTUNITY WL BE RATHER NARROW AS THE FLOW IS PROGGED TO VEER MORE TO THE WSW OVERNGT...SHIFTING THE HEAVIER SHSN TO THE E. ISSUED LES ADVY EARLIER TDAY FOR THIS EXPECTED SN. FARTHER W...FAIRLY DRY ENVIRONMENT AHEAD OF THE COLD FNT AS OBSVD THIS AFTN SUG THERE WL BE LTL IN THE WAY OF SN UNTIL THE COLD FROPA...ABOUT 03Z OVER THE FAR W AT IWD TO ARND 12Z AT ERY. WITH SHARP THERMAL GRADIENT/FGEN...SUSPECT THERE WL BE A PERIOD OF SN WITH THE FROPA...ESPECIALLY NEAR LK SUP WHERE THERE WL BE EXTRA MOISTENING/UPSLOPE FLOW. OVER THE SCNTRL... EXPECT ONLY SCT -SHSN WITH MORE DOWNSLOPE FLOW. ALTHOUGH THE SYNOPTIC SN WL CUT OFF QUICKLY WITH FAST ARRIVAL OF DEEP LYR QVECTOR DVGC/SUBSIDENCE...LES WL DVLP IN THE STRENGTHENING NW FLOW OF ARCTIC AIR LEFT IN THE WAKE OF DEPARTING LO. H85 TEMPS ARE PROGGED TO PLUMMET TO ARND -25C AT IWD BY 12Z THU. ANOTHER SGNFT FEATURE TNGT WL BE STRENGTHENING NW FLOW ASSOCIATED WITH STRONG CAD/IN ADVANCE OF APRCHG PRES RISE CENTER THAT IS FCST TO REACH THE W TOWARD 12Z. PREFER THE STRONGER H925 WINDS UP TO 40-45KTS SHOWN BY THE 12Z GFS/LOCAL WRF-ARW RUNS GIVEN THE STRENGTH OF THIS DISTURBANCE...AND THESE WINDS WL MIX EFFICIENTLY TO THE SFC WITH VIGOROUS CAD. THE COMBINATION OF THE STRONG WINDS AND FALLING TEMPS WL PUSH WIND CHILLS AS LO AS -20 TO -25F OVER GOGEBIC COUNTY. THU...GUSTY NW WINDS/VIGOROUS CAD WITH H85 TEMPS FALLING TO ARND -25C AND STRONG SUBSIDENCE/DEEP LYR QVECTOR DVGC WL BE IN PLACE BEHIND THE DEPARTING SFC LO/UPR DISTURBANCE AT DAYBREAK. EXPECT THE WINDS TO DIMINISH THU AFTN FOLLOWING PASSAGE OF PRES RISE CENTER TO THE E AFT 18Z. WITH THE SLOW APRCH OF HI PRES FM THE W...MODEL FCST SDNGS SHOW THE INVRN BASE AT IWD SINKING TO AOB 3K FT AGL BY LATE IN THE DAY AS WINDS BACK MORE TO THE W...DIMINISHING THE PCPN IN THAT AREA. THIS FLOW WL REMAIN FAVORABLE FOR AREAS FARTHER TO THE N THRU THE KEWEENAW...MAINTAINING HIER INVRN HGTS. EXPECT LES TO INTENSIFY OVER THE E WITH ENHANCED LLVL CNVGC PERSISTING AT THE END OF LONG NW FETCH OVER THE OPEN WATERS OF LK SUP. WITH INVRN BASE FCST ARND 5K FT AGL OVER THE KEWEENAW AND OVER THE E...LES CHART SUGS UP TO 6 INCHES OF SN PER 12 HR PERIOD. ALTHOUGH THESE AMOUNTS MAY NOT EASILY EXCEED WARNING THRESHOLDS...THE ARRIVAL OF MUCH COLDER AIR THAT DROPS H85 TEMPS TO ARND -25C AND THE DGZ ALMOST TO THE SFC OVER THE W AS WELL AS THE GUSTY WINDS WL HAMPER SN GROWTH...LEADING TO SMALLER SN FLAKES. WITH GUSTY WINDS...EXPECT EFFICIENT REDUCTION IN VSBY THAT JUSTIFIES GOING WITH WRNGS IN MOST COUNTIES EXCEPT FOR GOGEBIC COUNTY...WHICH WL NOT BE AS EXPOSED TO THE STRONG WINDS. WITH THE INFLUX OF COLD AIR...TEMPS WL BE STEADY OR SLOWLY FALLING THRU THE DAY. .LONG TERM /00Z FRI THROUGH NEXT WED/... THURSDAY NIGHT INTO FRI...NW LES WILL BE ONGOING AT THE START OF THE PERIOD...BUT INTENSITY SHOULD BE LIGHTER THAN THU MORNING AS DRY AIR AND SUBSIDENCE ALOFT LOWERS INVERSION HEIGHTS TOWARDS 4-5KFT. A SECONDARY SURGE OF LLVL MOISTURE WILL ARRIVE TOWARDS MIDNIGHT AS MID LVL RIDGING SLIDES TO THE E OF THE AREA. THIS ADDITIONAL MOISTURE BOOSTS THE INVERSION HEIGHTS TO 5-6KFT BY 06Z. AS THE HIGH MOVES FARTHER SE AND A WEAK TROUGH SLIDES OVER NRN LAKE SUPERIOR...LOW LEVEL FLOW WILL BECOME MORE FROM THE WSW. 850MB TEMPS WILL WARM SOME TO AROUND -22C...WHICH PLACES MORE OF THE DGZ IN THE BEST LIFT. THIS IS ALSO NOTED BY THE LAKE EFFECT SNOW PARAMETER INCREASING TO AROUND 0.75 OVER THE KEWEENAW BY 03Z FRI. THE BACKING WINDS WILL TEND TO FAVOR A STRONGER LES BAND FOCUSING SOMEWHERE OVER NWRN UPPER MI FROM NEAR ONTONAGON INTO THE KEWEENAW...AND SHOULD MOVE N THROUGH THE DAY AS WINDS BECOME MORE SWLY. LIKELY POPS FROM THE PREVIOUS FORECAST LOOK GOOD...SO WILL MAKE MINOR TREAKS TO THOSE GRIDS. ONGOING MULTI BANDED LES OVER ERN UPPER MI WILL MOVE OFFSHORE BY 18Z FRI AS WINDS BECOME SWLY...BUT THERE MAY BE A PERIOD OF STRONGER SNOW DUE TO CONVERGENCE AS WINDS BACK...BUT THAT MAY STAY JUST OFFSHORE AS WELL. WENT WITH THE LOW END OF GUIDANCE FOR TEMPS THU NIGHT. COLD...DRY AIR AND DECREASING WINDS WILL BRING LOW TEMPS DOWN TO NEAR -20 OVER THE INTERIOR WEST. WINDS WILL BE LIGHT AT AROUND 5KTS...BUT WIND CHILLS WILL STILL FALL TO AROUND -30. CONTINUED TO HIGHLIGHT THIS THREAT IN THE HWO. HIGHS WILL BE IN THE TEENS FRI. AN UPPER SHORTWAVE MOVES TO OUR S FRI AFTERNOON...LEADING TO SOME PRECIP SKIRTING THE SRN CWA. AT THIS TIME...THE MENOMINEE AREA LOOKS TO GET THE MOST SNOW FROM THIS SYSTEM...BUT WOULD BE AN INCH AT MOST. IF THE SYSTEM ENDS UP MOVING FARTHER N...SNOWFALL TOTALS WOULD BE HIGHER. SATURDAY...MODELS START TO DIVERGE ON SOLUTIONS AT THIS POINT...ALTHOUGH NOT DRASTICALLY...YET. MAIN DIFFERENCES COME FROM THE TIMING OF SFC RIDGING MOVING THROUGH. THE GFS IS ON THE SLOWER END OF GUIDANCE...WITH THE RIDGE AXIS OF THE CWA AT 18Z SAT. THE ECMWF IS FASTER...WITH THE AXIS OVER THE CWA AT 12Z SAT. THE BIG DIFFERENCE FROM THIS IS WITH WIND DIRECTIONS. AHEAD OF THE RIDGE AXIS...WINDS LOOK TO BE MORE NWLY...WHICH WOULD BRING SOME LIGHT LES NEAR LAKE SUPERIOR E OF MUNISING. WILL GO WITH A MORE BLENDED SOLUTION RIGHT NOW...WITH THE GREATEST POPS IN NW FLOW AREAS LATE FRI NIGHT/SAT MORN. HIGHS WILL BE IN THE TEENS TO LOW 20S SAT. SAT NIGHT THROUGH WED...A SERIES OF UPPER LEVEL DISTURBANCES MOVES THROUGH DURING THIS TIME...BUT MODELS ARE HAVING A HARD TIME HANDLING THESE SYSTEMS. NOT ONLY IS MODEL AGREEMENT POOR...RUN TO RUN DISCONTINUITY IS ALSO A PROBLEM DURING THIS TIME. THESE FACTORS LEAD TO WELL BELOW NORMAL CONFIDENCE IN THIS PART OF THE FORECAST. OVERALL...STUCK WITH CONSENSUS MODEL BLENDS FOR THIS PERIOD. THE GENERAL FEEL FROM THE MODELS IS THAT A LOW PRESSURE SYSTEM WILL MOVE INTO THE NRN PLAINS SAT NIGHT INTO SUN. THIS LEADS TO INCREASING TEMPS IN THE SW FLOW WAA REGIME AHEAD OF THE SYSTEM. THE BEST CHANCE FOR PRECIP CURRENLTY LOOKS TO BE SAT NIGHT INTO SUN...BUT AS STATED BEFORE CONFIDENCE IS LIMITED. A PERIOD OF DRIER WEATHER WILL PROBABLY RESULT LATE MON OR TUE AS UPPER LEVEL RIDGING MOVES OVER THE CWA. MODELS THEN SHOW A SHARP UPPER TROUGH MOVING TO THE CENTRAL CONUS WED...WHICH WOULD RESULT IN PRECIP OVER PARTS OF THE REGION. && .AVIATION /FOR THE 06Z TAF ISSUANCE/... BEHIND AN ARCTIC COLD FRONT OVERNIGHT...NORTHWEST WINDS WILL INCREASE AT ALL THREE SITES...FAVORING MDT/HVY LES AT IWD AND CMX. THE COMBINATION OF HEAVY LES AND STRONGER WINDS WILL SIGNIFICANTLY REDUCE VIS AT CMX DURING THE OVERNIGHT HOURS. LES SHOULD BEGIN TO EASE SLIGHTLY AROUND 18Z ON THURSDAY AS WINDS BEGIN TO BACK TO THE WEST AND DRIER AIR MOVES INTO THE AREA. EXPECT CONDITIONS TO IMPROVE TO VFR BY LATE AFTERNOON AT KSAW/KIWD AS A RIDGE BUILDS INTO THE AREA AND WINDS BACK WSW. HOWEVER...A MORE FAVORABLE TRAJECTORY ACROSS LAKE SUPERIOR WILL LIKELY BRING HEAVIER LAKE EFFECT SNOW SHOWERS BACK INTO KCMX DURING THE EVENING. && .MARINE /FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE/... GOING S GALES UP TO 35 KTS OVER ERN LK SUP THIS EVNG STILL APPEAR ON TRACK WITH SHARPENING PRES GRADIENT/AREA OF PRES FALLS PASSING TO THE N. AS THE SFC LO PASSES W-E LATE TNGT INTO THU...EXPECT SHARP WSHFT TO THE NW. INFLUX OF BITTERLY COLD AIR WILL ENHANCE MIXING OF WINDS UP TO 40-45 KTS JUST ABOVE THE SURFACE...GALES WILL DEVELOP IN MOST AREAS. WITH HI WAVES AS WELL...EXPECT HEAVY FREEZING SPRAY OVER THE ENTIRE LAKE. THE STRONGEST WINDS WILL TEND TO DIMINISH ON THU AFTERNOON. HIGH PRESSURE WILL BRIEFLY MOVE THROUGH THURSDAY NIGHT BEFORE A WEAK LOW PRESSURE SYSTEM MOVES OVER LAKE SUPERIOR ON FRIDAY. HIGH PRESSURE WILL RETURN ON SATURDAY...THEN WILL MOVE EAST SATURDAY NIGHT AHEAD OF AN APPROACHING LOW PRESSURE SYSTEM. THIS LOW PRESSURE SYSTEM LOOKS TO MOVE INTO THE AREA SUNDAY NIGHT INTO MONDAY BEFORE MOVING EAST MONDAY NIGHT. THERE IS STILL A LARGE AMOUNT OF UNCERTAINTY WITH THE TRACK OF THIS SYSTEM. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... LAKE EFFECT SNOW ADVISORY UNTIL 7 PM EST THIS EVENING FOR MIZ084. LAKE EFFECT SNOW WARNING FROM 7 AM THIS MORNING TO 1 AM EST FRIDAY FOR MIZ006-007-085. LAKE EFFECT SNOW WARNING UNTIL 7 AM EST FRIDAY FOR MIZ001-003. LAKE EFFECT SNOW ADVISORY UNTIL NOON CST THURSDAY FOR MIZ009. LAKE EFFECT SNOW ADVISORY UNTIL 7 AM EST THIS MORNING FOR MIZ007. LAKE EFFECT SNOW WARNING UNTIL 7 PM EST THIS EVENING FOR MIZ002. LAKE SUPERIOR... HEAVY FREEZING SPRAY WARNING FROM 7 AM THIS MORNING TO 7 AM EST FRIDAY FOR LSZ243>251-264>267. GALE WARNING UNTIL 7 PM EST THIS EVENING FOR LSZ266-267. GALE WARNING UNTIL 7 PM EST THIS EVENING FOR LSZ249>251-264-265. GALE WARNING UNTIL 1 PM EST /NOON CST/ THIS AFTERNOON FOR LSZ162- 263. GALE WARNING FROM 7 AM THIS MORNING TO 1 PM EST THIS AFTERNOON FOR LSZ242>245-248. HEAVY FREEZING SPRAY WARNING UNTIL 7 AM EST /6 AM CST/ FRIDAY FOR LSZ162-240>242-263. GALE WARNING UNTIL 7 AM EST /6 AM CST/ THIS MORNING FOR LSZ240- 241. LAKE MICHIGAN... HEAVY FREEZING SPRAY WARNING UNTIL 4 PM EST THIS AFTERNOON FOR LMZ221-248-250. GALE WARNING UNTIL 1 PM EST THIS AFTERNOON FOR LMZ221-248-250. && $$ SYNOPSIS...KC SHORT TERM...KC LONG TERM...TITUS AVIATION...JLB MARINE...KC
AREA FORECAST DISCUSSION...UPDATED
NWS GLASGOW MT
842 PM MST FRI JAN 20 2012 .SHORT TERM...FOR NORTHEAST MONTANA...TONIGHT THROUGH SUNDAY... NO APPARENT PRECIPITATION UPSTREAM AND THE HRRR MODEL KEEPS OUR AREA DRY TONIGHT...SO REMOVED POPS FROM MOST OF THE AREA...EXCEPT A SLIGHT CHANCE STRIP ALONG THE INTERNATIONAL BORDER. HOWEVER TEMPERATURES UPSTREAM HAVE WARMED CONSIDERABLY. THE NAM12 MODEL WAS USED FOR THE DIURNAL TRENDS FOR TONIGHT AND SATURDAY DUE TO EXPECTED RISING TEMPERATURES FROM THE SW. BLENDED THE HRRR WINDS INTO THE GRIDS TO INCREASE WINDS IN FAVORED AREAS FOR SE DIRECTION. THE 00Z SOUNDING REVEALED 850MB WARMING WITH TEMPERATURES ABOVE 0*C. THIS LOOKS GOOD FOR LIGHT FREEZING PRECIPITATION SATURDAY MORNING. THE GRIDS ALREADY MENTION THIS. SCT PREVIOUS DISCUSSION... WARMER CONDITIONS ARE EXPECTED THIS TERM WITH ABOVE NORMAL READINGS EXPECTED FOR THE FIRST TIME SINCE SUNDAY. A STRONG PACIFIC SYSTEM HAS PUSHED ONSHORE IN THE PACIFIC NW WITH A WARM FRONT NOW MOVING NE THROUGH SW MONTANA. THIS FRONT IS EXPECTED TO CONTINUE NE ALLOWING TEMPS TO RISE TONIGHT. 850 MB TEMPS RISE SIGNIFICANTLY AS THE REMAINING ARCTIC AIR-MASS GETS NUDGED TO OUR NE...WITH READINGS OVER GLASGOW RISING FROM ABOUT -12*C THIS AFTERNOON TO +3*C SATURDAY MORNING. LOW PRESSURE WILL BEGIN TO DEVELOP OVER SOUTHERN ALBERTA SATURDAY AS THE UPPER TROUGH MOVES IN. THE MODELS THEN TAKE THIS LOW EAST NEAR THE INTERNATIONAL BORDER...FAR ENOUGH NORTH FOR THE MILD PACIFIC AIR-MASS TO FLOOD INTO THE AREA SATURDAY. OF COURSE SNOW-COVER WILL TEMPER THIS WITH FURTHER COOLING IN THE NORTHERN ZONES DUE TO LACK OF MIXING. MOISTURE AHEAD OF THIS SYSTEM LOOKS MINIMAL SO SLIGHT CHANCE POPS LOOK GOOD FOR NOW. MODELS SEEM TO PUT A FINGER THOUGH ON SOME DEVELOPMENT SATURDAY AFTERNOON IN THE SOUTHEAST ZONES. THIS AREA QUICKLY MOVES EAST TO CREATE A HEADACHE FOR AREAS THERE. THE UPPER TROUGH LATE SATURDAY INTO SUNDAY WRAPS UP A BIT...ESPECIALLY ON THE GFS. THIS MODEL HAS BEEN CONSISTENT AND KNOCKS TEMPS BACK DOWN ACROSS THE AREA...AND MIXING NW WINDS TO THE SURFACE AS WELL. SOME SNOW-SHOWER ACTIVITY CAN BE EXPECTED TOO...SPREADING FROM NW TO SE DURING THE MORNING. SNOWFALL LOOKS TO BE LESS THAN AN INCH. JAMBA .LONG TERM...SUNDAY NIGHT THROUGH FRIDAY... NOT TOO MANY CHANGES TO THE LONG TERM...WITH THE MAIN FOCUS BEING THE RETURN OF THE POSSIBILITY OF ABOVE AVERAGE TEMPERATURES NEXT WEEK. BRIEF RIDGING STILL LOOKS TO MOVE IN EARLY IN THE WORK WEEK...FOLLOWED BY A SERIES OF SHORTWAVE TROUGHS. DECIDED TO RAISE TEMPS A BIT FOR NEXT WEEK DUE TO THE MAJORITY OF MODEL GUIDANCE HINTING TOWARDS WARMER TEMPERATURES COMPARED TO PREVIOUS RUNS. THE CHALLENGE WILL STILL BE FIGURING OUT JUST HOW WARM WE WILL GET...ESPECIALLY WITH A FEW BRIEF SHOTS OF COLD AIR WITH THE PASSING SHORTWAVES AND CORRESPONDING COLD FRONTS. ALTHOUGH WINDS STILL LOOK TO BE STRONG LATER IN THE PERIOD...THE AMOUNT OF MIXING STILL MAY PREVENT US FROM BRINGING THE WARMER AIR DOWN TO THE SURFACE. FORECASTED HIGHS ARE STILL A BIT BELOW MOST MODEL SOLUTIONS. WEDNESDAY STILL LOOKS TO BE THE WARMEST DAY NEXT WEEK...WITH THE GFS BRINGING 850 TEMPS AROUND 4C TO 8C OVER THE CWA. HOWEVER...THE 12Z ECMWF SUGGESTS THAT WEDNESDAY AND THURSDAY LOOK TO BE WARM...WITH THURSDAY BEING THE WARMER OF THE TWO DAYS. 850 TEMPS ARE JUST A BIT HIGHER ON THURSDAY ACCORDING TO THE ECMWF BY ABOUT 2C TO 4C COMPARED TO WEDNESDAY. EITHER WAY...NEXT WEEK STILL LOOKS TO BE A WELCOMED RETURN TO WARMER TEMPERATURES. BARNWELL PREVIOUS LONG TERM DISCUSSION...PATTERN RETURNS TO WHAT HAS BEEN COMMON THIS WINTER...ZONAL FLOW OFF THE PACIFIC WITH A SERIES OF WEAK RIDGES AND TROF...AND ARCTIC AIRMASS STAYING WELL TO THE NORTH. MODEL TIMING OF THE FEATURES NOT TOO FAR OFF FROM EACH OTHER...ALTHOUGH THIS DOES SLIP TOWARD THE END OF THE FORECAST PERIOD. UPPER TROF EXITING THE REGION SUNDAY NIGHT WITH RIDGE SLIDING ACROSS THE STATE ON MONDAY WITH ANOTHER TROF PUSHING THROUGH THE PACIFIC NORTHWEST. COLD FRONT IS PUSHED INTO THE STATE MONDAY NIGHT AS UPPER TROF TRACKS ALONG THE CANADIAN BORDER. JET PUNCHES INTO WESTERN CANADA BEHIND THE TROF ON TUESDAY NIGHT..DEVELOPING INTO A STRONG CHINOOK ACROSS MONTANA ON WEDNESDAY. AS JET DIVES INTO THE NORTHERN PLAINS...COLD FRONT DROPS THROUGH MONTANA...AND ENOUGH DYNAMICS AND MOISTURE FOR A LITTLE PRECIPITATION ON WEDNESDAY. PATTERN REPEATS FOR THURSDAY INTO THURSDAY NIGHT...ALTHOUGH AIRMASS SLIGHTLY COLDER BEHIND THIS SECOND COLD FRONT. POTENTIAL FOR WINDY CONDITIONS WILL BE INCREASING ALTHOUGH MIXING WILL CONTINUE TO BE A PROBLEM...ESPECIALLY WITH INCREASED SNOW COVER IN CONTRAST TO EARLIER IN THE MONTH. EBERT && .AVIATION... THERE WILL BE A SCATTERED TO BROKEN LAYER AROUND 2K FT AGL OVER PARTS OF THE FORECAST AREA TONIGHT...OTHERWISE MAINLY VFR WITH BROKEN TO OVERCAST LAYERS ABOVE 8K FT AGL. E WINDS 10 TO 15 KT AT GGW. SLIGHT CHANCE OF A LITTLE LIGHT FREEZING RAIN LATE TONIGHT AND SATURDAY MORNING. SIMONSEN && .GLASGOW WATCHES/WARNINGS/ADVISORIES...NONE. && $$ WEATHER.GOV/GLASGOW
AREA FORECAST DISCUSSION
NWS HASTINGS NE
510 PM CST FRI JAN 20 2012 .AVIATION...00Z KGRI TAF. CEILINGS ARE GOING TO BE A TOUGH CALL THIS EVENING. SOME STRATUS ARE HEADING TOWARD THE TERMINAL FROM THE NORTH...BUT ISENTROPIC DOWNGLIDE WILL BE COMPETING AGAINST THE STRATUS HOLDING TOGETHER FOR LONG. LOOKING AT THE LATEST SATELLITE DATA AND SPEED TOOLS...IT APPEARS THAT THE STRATUS SHOULD ARRIVE A BIT OVER AN HOUR AFTER THIS FORECAST IF VALID...BUT WITH ISENTROPIC DOWNGLIDE...WILL LIKELY ONLY HOLD TOGETHER THROUGH THE EVENING AND THEN SCATTER BY THE EARLY OVERNIGHT. WIND WILL SWITCH FROM THE NORTH TO THE SOUTH OVERNIGHT AS A SURFACE HIGH SLIDES EAST. SOUTH WIND CAN GET A BIT GUSTY BY SATURDAY AFTERNOON AS THE SURFACE PRESSURE GRADIENT INCREASES. && .PREV DISCUSSION... /ISSUED 318 PM CST FRI JAN 20 2012/ SHORT TERM...THROUGH 00Z SUNDAY. MORNING UPPER AIR ANALYSIS INDICATES ZONAL TO NORTHWESTERLY UPPER LEVEL FLOW PERSISTING ACROSS MUCH OF THE CONUS. A 90KT MID LEVEL JET AXIS IS ALSO NOTED EXTENDING FROM THE NORTHERN PLAINS TO THE MID-ATLANTIC. WATER VAPOR IMAGERY INDICATES INCREASED MID LEVEL MOISTURE ACROSS THE NORTHERN HALF OF THE CONUS...WITH A TROPICAL MID LEVEL MOISTURE TAP ALSO NOTED APPROACHING NORTHWESTERN MEXICO FROM THE PACIFIC. AT THE SURFACE A RIDGE OF HIGH PRESSURE REMAINS ANCHORED ACROSS MUCH OF THE PLAINS...WITH AFTERNOON TEMPERATURES REMAINING IN THE 20S ACROSS MUCH OF THE CENTRAL PLAINS. WARMER AIR IS NOT FAR AWAY HOWEVER AS A STRONG LOW LEVEL BAROCLINIC ZONE CURRENTLY EXTENDS ALONG MUCH OF THE HIGH PLAINS...WITH A 20-30 DEGREE TEMPERATURE GRADIENT CURRENTLY EXISTING WITHIN ABOUT 50 MILES ACROSS THE LOW LEVEL BAROCLINIC ZONE. MID AFTERNOON SATELLITE IMAGERY INDICATES ALTO-STRATUS OVER SOUTH DAKOTA...MOVING SOUTH/SOUTHEAST INTO NORTHERN NEBRASKA. SATELLITE IMAGERY ALSO INDICATES THE WESTERN EDGE OF THIS CLOUD DECK IS ERODING...THUS MAKING IT APPEAR AS THOUGH WE STAND A BETTER CHANCE OF RECEIVING A GLANCING BLOW ACROSS OUR NORTHEASTERN CWA RATHER THAN BE COMPLETELY OVERTAKEN BY CLOUDS THIS EVENING. THIS ALSO FITS WELL WITH THE LATEST RUC GUIDANCE...WHICH INDICATES ISENTROPIC DOWN GLIDE IS INFILTRATING MUCH OF THE REGION. GIVEN ALL THIS...WILL KEEP MOSTLY CLOUDY SKIES GOING ACROSS OUR NORTHEAST THROUGH LATE EVENING...WITH LOCATIONS FARTHER SOUTHWEST HOPEFULLY REMAINING WEST/SOUTHWEST OF THE CLOUD DECK. THIS WILL BE SOMETHING FOR THE EVENING SHIFT TO MONITOR HOWEVER...JUST IN CASE THE CLOUD DECK DOES MANAGE TO PUSH FARTHER SOUTHWEST THAN CURRENTLY FORECAST. CLEARING SKIES...DECREASING LOW LEVEL WINDS AND WEAK SURFACE RIDGING SHOULD PROMOTE A DECENT DROP OFF IN TEMPERATURES TONIGHT AND CURRENTLY HAVE 20-25 DEGREE DROP OFFS IN THE FORECAST...WHICH YIELDS OVERNIGHT LOWS IN THE SINGLE DIGITS. THE SURFACE RIDGE IS EXPECTED TO PUSH OFF TO THE EAST EARLY SATURDAY MORNING...WITH LOW LEVEL RETURN FLOW REESTABLISHED ACROSS THE CENTRAL PLAINS BY SUNRISE SATURDAY. THIS LOW LEVEL RETURN FLOW WILL PROMOTE WEAK LOW LEVEL WAA WITHIN A SOUTH/SOUTHEASTERLY LOW LEVEL WIND FIELD. ~25 DEGREE RISES ARE EXPECTED FOR THE MOST PART SATURDAY...WHICH YIELDS SATURDAY AFTERNOON HIGHS IN THE UPPER 20S TO UPPER 30S ACROSS THE CWA. LONG TERM...00Z SUNDAY THROUGH FRIDAY. THE START OF THE LONG TERM PERIOD WILL FEATURE AN H5 RIDGE ACROSS THE CENTRAL UNITED STATES WITH A LARGE TROUGH IN THE WEST. THERE IS GENERAL CONSENSUS THAT THE WESTERN U.S. TROUGH WILL MOVE ACROSS THE CENTRAL PLAINS LATE SATURDAY NIGHT INTO SUNDAY...HOWEVER FINDING AGREEMENT IN THE DETAILS REMAINS ELUSIVE. DIFFERENCES REMAIN AMONGST THE VARIOUS MODEL SOLUTIONS IN THE OVERALL STRENGTH/TIMING WHICH OBVIOUSLY HAVE LARGE IMPACTS IN REGARDS TO POPS AND PRECIPITATION TYPE. AT THIS POINT...HAVE CONTINUED TO CARRY A BLENDED MODEL SOLUTION WHICH GIVES POPS GENERALLY IN THE 30 PERCENT RANGE ON SUNDAY. THIS ALSO LINGERS A POP IN THE FAR EAST FOR SUNDAY EVENING WHICH ACCOUNTS FOR SOME OF THE SLOWER MODEL SOLUTIONS...IN PARTICULAR THE ECMWF. TEMPERATURES AND THE OVERALL THERMAL PROFILE REMAINS UNCERTAIN THOUGH THE GENERAL TREND SEEMS TO KEEP WARMER H85 TEMPERATURES IN THE MORNING...FOLLOWED BY COLDER AIR ARRIVING BEHIND A COLD FRONT IN THE AFTERNOON. IF PRECIPITATION STARTS EARLY ENOUGH ON SUNDAY...COULD SEE SOME POTENTIAL FOR LIGHT FREEZING RAIN DUE TO THE EXPECTED BELOW FREEZING SURFACE TEMPERATURES...BUT WITH CONFIDENCE STILL SO LOW IN THE DETAILS...WILL INSTEAD OPT FOR A RAIN/SNOW MIX. IN FACT...COULD SEE SOME JUSTIFICATION FOR A RAIN/SNOW MIX MUCH OF THE DAY DEPENDING ON THE TIMING OF THE COLDER AIR ALOFT. IN REGARDS TO SUNDAY EVENING...WILL GO WITH SNOW SINCE MOST SOLUTIONS HAVE THE COLD AIR IN PLACE BY THAT TIME. ANOTHER CONCERN ON SUNDAY WILL BE STRONG WINDS BEHIND THE COLD FRONT. STRONG PRESSURE RISES ARE SHOWN ACROSS THE FORECAST AREA. MOMENTUM TRANSFER FROM NAM BUFR SOUNDINGS SUGGEST GUSTS COULD APPROACH 40 KTS ACROSS MUCH OF THE FORECAST AREA...WITH EVEN STRONGER WINDS POTENTIALLY TAKING HOLD IN THE SOUTHWEST. CURRENTLY WE ARE HIGHLIGHTING THE STRONGER WINDS IN THE HAZARDOUS WEATHER OUTLOOK...AND WILL LET THAT WORDING CONTINUE. A DRY PERIOD TAKES HOLD AGAIN FOR OVERNIGHT SUNDAY INTO AT LEAST EARLY TUESDAY AS ANOTHER H5 RIDGE DOMINATES THE CENTRAL PORTION OF THE COUNTRY. THE NEXT WAVE MOVES THROUGH THE AREA TUESDAY INTO TUESDAY NIGHT...HOWEVER AGAIN THERE ARE DIFFERENCES IN TIMING AMONGST THE MODELS. WILL MAINTAIN CONTINUITY FOR NOW AND HOLD ONTO THE MAIN PRECIPITATION CHANCES TUESDAY NIGHT. PRECIPITATION TYPE COULD AGAIN BE AN WITH THE GFS COLDER THAN THE ECMWF. HAVE GONE WITH A RAIN/SNOW COMBINATION IN THE SOUTH...BUT WILL GO ALL SNOW IN THE NORTH WHERE EVEN THE WARMER ECMWF DROPS H85 TEMPERATURES BELOW FREEZING TUESDAY EVENING. THE REMAINDER OF THE FORECAST PERIOD APPEARS TO BE GENERALLY SUPPORT ABOVE NORMAL TEMPERATURES WITH HIGHS PRIMARILY IN THE 40S. THE WARMEST DAY COULD TURN OUT TO BE THURSDAY WITH SOME LOCATIONS POTENTIALLY PUSHING THE 50 DEGREE MARK. && .GID WATCHES/WARNINGS/ADVISORIES... NE...NONE. KS...NONE. && $$ AVIATION...HEINLEIN SHORT TERM...BRYANT LONG TERM...KING
AREA FORECAST DISCUSSION
NWS NORTH PLATTE NE
1249 PM CST THU JAN 19 2012 .UPDATE... ARCTIC HIGH PRESSURE CONTINUES TO DOMINATE THE REGION. TEMPS HAVE BEEN SLOW TO RISE THIS MORNING...AND HAVE DROPPED HIGHS AND HOURLY TEMPS FOR TODAY. FOLLOWED CLOSE TO RUC GUIDANCE...WHICH HAS THE BEST CURRENT POSITION BASED ON LATEST OBS. && .AVIATION... VFR CONDITIONS TODAY AS ARCTIC HIGH PRESSURE DOMINATES THE PLAINS. WARM AIR WILL LIFT NORTHEAST AS CENTER OF HIGH SLIDES TO THE SOUTHEAST OVERNIGHT. MODELS INCREASE LL RH VALUES LATE TONIGHT...WITH MOS GUIDANCE SHOWING MVFR/IFR CIGS DEVELOPING OVER NORTHERN AND CENTRAL NEBRASKA. HIGHER CONFIDENCE WILL SEE AN IMPACT AT KVTN...HOWEVER MODELS ARE FASTER THAT ACTUALLY HAPPENING WITH RETREATING THE COLD AIR. THIS MAY RESULT IN STRATUS IMPACTING PARTS OF SW NEBRASKA...AND THE KLBF TERMINAL. WILL MONITOR FOR POSSIBLE ADDITION TO LBF TAF. ANY STRATUS THAT DOES DEVELOP WILL BE SLOW TO LIFT TOMORROW MORNING AND EARLY AFTERNOON. && .PREV DISCUSSION.../ISSUED 341 AM CST THU JAN 19 2012/ SYNOPSIS... HAND ANALYSIS OF THE 19.00Z H25 AND H5 LEVELS REVEALS NORTHWESTERLY FLOW ACROSS THE NORTHERN AND CENTRAL HIGH PLAINS...WITH STRONG UPPER LEVEL JET SUPPORT OF GREATER THAN 150 KTS EDGING FROM THE EASTERN CASCADES TOWARD THE BLACK HILLS REGION OF SOUTH DAKOTA. A SHORTWAVE TROUGH WAS ANALYZED IN THE MID LEVELS NEAR LAKE SUPERIOR...WITH ANOTHER WAVE CLOSING IN ON THE PACIFIC NORTHWEST. AT THE SURFACE...COLD ARCTIC AIR HAS ONCE AGAIN FILTERED ACROSS THE SAND HILLS REGION OF NEBRASKA...WITH SUB ZERO TEMPERATURES ALONG THE NIOBRARA RIVER VALLEY EARLY THIS MORNING. FURTHER SOUTH...SINGLE DIGIT READINGS ARE THE NORM. REGIONAL RADARS ARE INTERROGATING A BAND OF LIGHT SNOW ACROSS WESTERN SOUTH DAKOTA...BUT GENERALLY VOID OF PRECIPITATION ELSEWHERE. DISCUSSION... ANOTHER TRICKY TEMPERATURE FORECAST IS IN STORE FOR THIS AFTERNOON AS THE ARCTIC FRONT RETREATS NORTH AND EAST...AND SOUTHERLY FLOW RETURNS OVER SOUTHERN AND WESTERN NEBRASKA. THE MODELS INDICATE WARMING ALOFT...AS THE CONSENSUS SUGGESTS H85 TEMPERATURES GENERALLY RANGING FROM 8C ACROSS SOUTHWEST NEBRASKA TO -8C OVER NORTH CENTRAL NEBRASKA BY 00Z FRIDAY. HOWEVER CLOSER TO THE SURFACE...H925 TEMPERATURES REMAIN BELOW 0C ACROSS MUCH OF THE CWA THROUGH 00Z FRIDAY...WITH -2 AT LBF AND -12C AT ONL. THE 00Z UNR SOUNDING INDICATES ABOUT 2-3K FT DEPTH OF THE COLDER AIR...SO ITS GONNA TAKE SOME MIXING TO SCOUR OUT THE LAYER...BUT UNFORTUNATELY WITH SOUTH TO SOUTHEASTERLY FLOW...MIXING WILL BE RATHER LIMITED TODAY. SO ONLY THE FAR WESTERN PORTIONS OF THE CWA MAY SEE TEMPERATURES ABOVE 0C THIS AFTERNOON...ELSEWHERE TEMPERATURES WILL RANGE FROM THE LOW TEENS OVER NORTH CENTRAL NEBRASKA TO THE LOW 30S AT LBF. FOR TONIGHT...AGAIN WARMING ALOFT WILL OCCUR...BUT WITH THE SHALLOW ARCTIC AIR MASS IN PLACE...STILL LOOKING FOR BELOW AVERAGE LOWS OVER MUCH OF THE CWA...WITH LOWS RANGING FROM THE SINGLE DIGITS ACROSS NORTH CENTRAL NEBRASKA...TO POSSIBLY LOW TO MID 20S ACROSS SOUTHWEST NEBRASKA. MODELS CONTINUE TO INDICATE A CHANCE OF PRECIPITATION ALONG NORTHERN NEBRASKA OVERNIGHT TONIGHT AS WELL. BEST FORCING AND SUPPORT FOR THE PRECIPITATION HAS TRENDED NORTH INTO SOUTH DAKOTA THE PAST COUPLE MODEL RUNS...WITH FAVORABLE SATURATION PRESSURE DEFICITS NORTH OF THE CWA. BUT FAVORABLE UPPER LEVEL JET SUPPORT WILL BE IN THE REGION...AND MODEL SOUNDINGS INDICATE SUFFICIENT SATURATION OVER NORTHERN NEBRASKA...SO NOT READY TO PULL THE PLUG ON PRECIPITATION CHANCES YET. WILL LEAVE POPS AT CHANCE TO LOW END LIKELY ACROSS NORTH CENTRAL NEBRASKA FOR NOW...BUT QPF AMOUNTS LOOK LIGHT AT BEST. MODEL SOUNDINGS ALSO INDICATE THE POTENTIAL FOR A MIXED BAG OF PRECIPITATION...WITH POSSIBLY SOME IP OR ZR AS WAA PUSHES TEMPERATURES ALOFT ABOVE 0C ACROSS NORTHERN NEBRASKA...THIS WILL NEED TO BE RE-EVALUATED WITH THE NEWEST MODEL GUIDANCE AND FOR NOW WILL LEAVE AS -SN AS TEMPERATURE CONFIDENCE IS LOW. ARCTIC FRONT PLUNGES SOUTH ONCE AGAIN ON FRIDAY...AND AGAIN A DIFFICULT HIGH TEMPERATURE FORECAST IS IN STORE. WHAT IS CERTAIN IS NORTHERN NEBRASKA WILL BE BELOW AVERAGE...WITH HIGHS IN THE TEENS...SOUTH OF INTERSTATE 80...AND OVER THE HIGHER TERRAIN OF THE WEST...40S MAY BE POSSIBLE. THE ARCTIC AIR MASS MODIFIES AND BUILDS EAST AGAIN ON SATURDAY...AS SOUTHERLY FLOW RETURNS TO THE PLAINS. H925 TEMPERATURES BY LATE SATURDAY AFTERNOON SHOULD PUSH WELL ABOVE 0C FOR MUCH OF THE CWA...WITH THE EXCEPTION OF OUR FAR EASTERN ZONES...SO HIGHS SHOULD RANGE FROM THE LOW 30S OVER THE EAST...TO NEAR 50 ACROSS THE FAR WEST. SUNDAY MAY BE INTERESTING...THE MODELS HAVE BEEN ADVERTISING A RAPIDLY ADVANCING MID TO UPPER TROUGH PASSAGE OVER THE LAST FEW RUNS. THE EUROPEAN SOLUTION THIS EVENING IS NOW INDICATING A DEEPER AND POTENTIALLY MORE SIGNIFICANT PASSAGE FOR THE CWA. THIS NEW SOLUTION WOULD GIVE THE CWA WIDESPREAD ACCUMULATING QPF...NOT SIGNIFICANT AMOUNTS...BUT WITH THE DRY WINTER THUS FAR...ANY ACCUMULATIONS WOULD BE APPRECIATED. GFS AND NAM CONTINUE TO TARGET NORTH OF THE CWA. THE EURO PRECIP FIELD MAY BE OVERDONE...BUT WORTHY OF AT LEAST A SLIGHT CHANCE MENTION FOR NOW. AS FOR PTYPE...TEMPERATURES AT THIS POINT IN TIME LOOK TO BE WARM ENOUGH FOR ALL RAIN OVER MUCH OF THE CWA...BUT GIVEN IT/S JANUARY...WILL GO WITH RAIN OR SNOW FOR NOW. FOR THE START IF THE WORK WEEK...SLIGHTLY WARMER AIR SHOULD RETURN EARLY NEXT WEEK WITH HIGHS AT OR SLIGHTLY ABOVE CLIMO. ANOTHER QUICK MOVING TROUGH WILL CROSS THE NORTHERN PLAINS ON TUESDAY...BRINGING ANOTHER SHOT...ALBEIT SLIGHT CHANCE AT THIS POINT IN TIME...OF PRECIPITATION...MADE ON MINOR ADJUSTMENTS TO THE EXTENDED BEYOND SUNDAY AFTERNOON. && .LBF WATCHES/WARNINGS/ADVISORIES...NONE. && $$ UPDATE/AVIATION...MASEK
AREA FORECAST DISCUSSION
NWS HASTINGS NE
1123 AM CST THU JAN 19 2012 .AVIATION...18Z TAF. ARCTIC HIGH PRESSURE WILL SLIDE TO THE EAST TODAY INTO TONIGHT. THIS WILL ALLOW RETURN FLOW...AND WARMER AIR TO RETURN TO THE AREA. AS THE WARMER AIR RETURNS...THERE ARE SOME SIGNS STRATUS COULD TRY TO DEVELOP OVERNIGHT...BUT THE 12Z NAM IS NOW SLOWER IN BRINGING THE LOW CLOUDS TO KGRI. IN FACT...IT GENERALLY SUGGESTS THAT MID AND HIGH LEVEL CLOUDS WILL DOMINATE UNDER THE H85 WARM AIR ADVECTION...HOWEVER ONCE THE ARCTIC AIR MOVES SOUTH AGAIN ON FRIDAY...STRATUS COULD COME WITH IT. WILL HOLD ONTO A VFR FORECAST THROUGH TONIGHT...BUT WILL CARRY SCATTERED CLOUDS AROUND 2500FT IN ORDER TO SUGGEST THERE IS SOME CHANCE LOWER CLOUDS COULD TRY TO DEVELOP OVERNIGHT. WILL GO WITH AN MVFR CEILING LATE IN THE PERIOD...WHICH IS IN LINE WITH THE NAM...AS THE ARCTIC AIR AGAIN INVADES THE AREA. WINDS WILL START OUT LIGHT AND VARIABLE...BUT SHOULD TURN SOUTHERLY THIS AFTERNOON AS THE HIGH SLIDES EAST. WINDS WILL BECOME NORTHERLY AGAIN LATE IN THE PERIOD AS ANOTHER COLD FRONT DROPS SOUTH ACROSS THE TERMINAL LOCATION. && .PREV DISCUSSION... /ISSUED 1027 AM CST THU JAN 19 2012/ UPDATE...SENT A QUICK UPDATE TO ADJUST THE HOURLY TEMPERATURE CURVE TO BETTER REFLECT REALITY...OTHERWISE THE REMAINDER OF THE FORECAST LOOKS ON TRACK FOR TODAY. PREV DISCUSSION... /ISSUED 639 AM CST THU JAN 19 2012/ UPDATE...JUST RAN A QUICK UPDATE TO TABULAR AFM/PFM PRODUCTS AND WEB-BASED PRODUCTS TO BRING NEXT SEVERAL HOURS OF TEMP/DEWPOINT TRENDS MORE IN LINE WITH CURRENT OBS...AS COLDER AND DRIER AIR HAS PUSHED MORE AGGRESSIVELY SOUTHWARD INTO SOUTHERN PORTIONS OF THE CWA THAN EXPECTED EVEN A FEW HOURS AGO. ONLY MODEL/GUIDANCE REALLY PROVING USEFUL FOR THESE VERY SHORT TERM TRENDS IS GFS LAMP GUIDANCE. WIND CHILLS BETWEEN -10 AND -15 WILL BE WIDESPREAD ACROSS MOST ALL NEB ZONES FOR THE NEXT FEW HOURS...WITH KS ZONES MORE SO -5 TO -10. ALTHOUGH NO CHANGES WERE MADE TO AFTERNOON HIGH TEMPS AT THIS TIME...INTERESTING TO NOTE THAT BOTH THE 09Z RUC AND HRRR SUGGEST THAT THE TRI-CITIES WILL RECOVER ENOUGH TO POSSIBLY REACH 20 THIS AFTERNOON...BUT THIS SEEMS TOO OPTIMISTIC AT THIS TIME AND WILL STICK WITH GOING FORECAST. PREV DISCUSSION... /ISSUED 451 AM CST THU JAN 19 2012/ SHORT TERM...THROUGH SATURDAY NIGHT. PRIMARY CONCERN DURING THE NEXT 72 HOURS CONTINUES TO BE TEMPERATURE TRENDS...WITH THE NEXT REGIONAL SNOW EVENT FROM THURSDAY NIGHT INTO FRIDAY STILL PROGGED TO MISS MOST...IF NOT ALL OF THE CWA TO THE NORTHEAST...FOCUSING ALONG AN AXIS FROM SD THROUGH NORTHEAST NEB/NORTHERN IA. THAT BEING SAID...ALTHOUGH NOT OVERLY CONCERNED AT THIS POINT...WILL NEED TO MONITOR LOW LEVEL MOISTURE TRENDS CLOSELY LATE THURS NIGHT INTO FRIDAY MORNING TO MAKE SURE THAT NO LIGHT FREEZING DRIZZLE TRIES TO SNEAK UP ON US. 09Z OBJECTIVE SURFACE ANALYSIS REVEALS THAT THE WELL ADVERTISED ARCTIC COLD FRONT HAS MADE STEADY PROGRESS SOUTHWARD ACROSS THE CWA THROUGH THE NIGHT...PUSHED ALONG BY A BROAD 1024MB HIGH CENTERED FROM MT TO NORTHERN SD. TEMPERATURES AT 09Z RANGED FROM 2 AT ORD...TO 18 AT BELOIT. ADDING TO THE INVADING BITTERNESS ARE STEADY NORTH-NORTHEAST BREEZES OF 10-20 MPH...YIELDING WIND CHILL VALUES RANGING FROM -10 TO -15 NORTH OF I-80...TO NEAR ZERO IN THE SOUTH. DESPITE PLENTIFUL MID LEVEL RADAR RETURNS EARLIER THE NIGHT ACROSS THE NORTHEAST...IT IS LIKELY THAT FLURRY ACTIVITY DID NOT MATERIALIZE ACROSS THE NORTHEAST. ALOFT...WATER VAPOR IMAGERY AND SHORT TERM MODEL DATA FEATURE VERY FAST NORTHWEST FLOW BISECTING THE CONUS FROM NORTHWEST TO SOUTHEAST...HIGHLIGHTED BY A 140+KT 300MB JET STREAK CUTTING ACROSS EASTERN NEB. ALTHOUGH THE PRIMARY MID LEVEL SHORTWAVE/500MB VORT MAX OF NOTE IS ALREADY WELL NORTHEAST INTO THE GREAT LAKES...LIFT ASSOCIATED WITH THE UPPER JET STREAK HAS GENERATED PLENTIFUL CIRRUS OVER MAINLY NEB ZONES OVERNIGHT...BUT KEEPING PRIMARY ZONE OF MID LEVEL SATURATION/POSSIBLE LIGHT SNOW PRODUCTION OFF TO THE NORTH AND EAST. TODAY...THE AFOREMENTIONED STRONG UPPER JET AXIS DRIFTS NORTHEAST...WITH ITS CENTER ALONG AN AXIS FROM CENTRAL ND TO NORTHERN IL BY 00Z THIS EVENING. AS A RESULT...THE EXTENSIVE HIGH LEVEL CLOUD COVER ACROSS MOST OF THE CWA SHOULD GRADUALLY SCATTER OUT AND/OR LIFT NORTHEAST AS WELL...WITH AT LEAST PARTLY CLOUDY SKIES ANTICIPATED MOST AREAS FOR THIS AFTERNOON. EVEN IF THE SUN IS OUT...IT WON/T DO A WHOLE LOT TO MASK WHAT IS ALMOST CERTAINLY TO BE THE OVERALL COLDEST DAY OF THE WINTER SO FAR FOR MOST OF THE CWA. AS THE DAY WEARS ON...THE CENTER OF THE SURFACE HIGH WILL MIGRATE INTO MN/IA...ALLOWING BREEZES TO GRADUALLY DIMINISH INTO THE 5-10 MPH RANGE FOR THIS AFTERNOON AS THEY GRADUALLY SHIFT FROM MORE NORTHERLY TO MORE EASTERLY/SOUTHEASTERLY BY LATE IN THE DAY. AS FOR TEMPS...YET AGAIN OPTED TO LOWER HIGHS BY 2-5 DEGREES FROM PREVIOUS FORECAST IN MOST AREAS...LEANING TOWARD THE COLDER MAV GUIDANCE. THIS YIELDS HIGHS RANGING FROM ONLY 10-13 DEGREES IN THE NORTHEAST CWA...TO MID 20S FAR SOUTH AND WEST WHERE THE SOUTHEAST FLOW AROUND THE HIGH SHOULD HELP MODERATE THINGS SOMEWHAT. AS FOR WIND CHILLS THIS MORNING...VALUES WILL CONTINUE TO RANGE BETWEEN -10 AND -17 ACROSS MUCH OF THE NORTHEAST 1/2 OF THE CWA THROUGH AT LEAST MID-MORNING...WHICH WILL BE ABOVE ADVISORY CRITERIA OF -20 BUT NOT BY MUCH. ITS CLOSE ENOUGH THAT WILL PUT A MENTION IN THE HAZARDOUS WEATHER OUTLOOK. TONIGHT...THE NEXT BATCH OF BROAD...LOW AMPLITUDE SHORTWAVE ENERGY QUICKLY APPROACHES THE CENTRAL CONUS FROM THE NORTHWEST. WITHIN THE ENTRANCE REGION OF THE PRIMARY UPPER JET AXIS MIGRATING ACROSS THE UPPER MISS VALLEY/GREAT LAKES...AN IMPRESSIVE ZONE OF ISENTROPIC LIFT/MID LEVEL CONVERGENCE WILL SET UP ALONG AND NORTH OF THE PRIMARY LOW-MID LEVEL TEMPERATURE GRADIENT CENTERED FROM SD INTO NORTHEAST NEB/IA. THIS WILL BE THE OBVIOUS FOCUS FOR THE START OF A MEASURABLE SNOW EVENT FOR THOSE AREAS. ALTHOUGH IT IS SEEMING MORE AND MORE LIKELY THAT THE CWA WILL MISS OUT ON THIS ACTION...PREVIOUS FORECAST HAD SOME LOW POPS ACROSS THE NORTHEAST...AND WILL CONTINUE THIS MENTION AFTER MIDNIGHT FOR MAINLY THE NORTHEAST 1/5 OF THE CWA JUST IN CASE THE FAR SOUTHERN EDGE OF THIS ACTIVITY SLIPS IN. ANY ACCUMULATIONS...IF ANY...WOULD NOT AMOUNT TO MORE THAN A FEW TENTHS. INTERESTINGLY...IF ANYTHING DOES HAPPEN TO FALL IN THE FAR NORTH TONIGHT...IT MIGHT ACTUALLY FAVOR THE FORM OF LIGHT SLEET BASED ON FORECAST SOUNDINGS...BUT WILL LEAVE IT AS SNOW MENTION FOR NOW. HAVE ALSO BEEN GROWING A BIT LEARY OF POSSIBLE LIGHT FREEZING DRIZZLE ACROSS NORTHERN PORTIONS OF THE AREA GIVEN THE GOOD LOW LEVEL WARM ADVECTION...BUT THINKING AT THIS POINT IS THAT ANY POTENTIAL STRATUS LAYER WOULD BE TOO SHALLOW TO SUPPORT THIS. SOMETHING TO WATCH. AS FOR LOW TEMPS...CHANGED THEM LITTLE...ALTHOUGH CONFIDENCE IN HOURLY TRENDS IS QUITE LOW AS TEMPS COULD EASILY DISPLAY STEADY/SLOWLY RISING CHARACTERISTICS AS BREEZES TURN SOUTHERLY. KEPT IT SIMPLE FOR NOW THOUGH...INDICATING MOST AREAS BOTTOMING OUT BETWEEN 9 AND 15 DEGREES...ALTHOUGH THIS MIGHT END UP BEING EARLIER IN THE NIGHT VERSUS LATER FOR SOME PLACES. FRIDAY...THE MAIN BATCH OF SHORTWAVE ENERGY PASSES THROUGH THE CENTRAL PLAINS...ALTHOUGH THE UPPER JET FORCING CONTINUES TO DIRECT THE MAIN PRECIP EVENT FROM EASTERN SD INTO NORTHERN IA/SOUTHERN MN AND POINTS EAST. THUS LEFT PRECIP MENTION OUT OF THE FORECAST...ALTHOUGH ONCE AGAIN WILL HAVE TO MONITOR DEPTH OF POSSIBLE STRATUS LAYER CLOSELY FOR OUTSIDE CHANCE OF SNEAKY LIGHT FREEZING DRIZZLE THREAT...BUT JUST SEEMS RATHER UNLIKELY AT THIS JUNCTURE. AS FOR HIGH TEMPS...THE SOUTHERN EDGE OF THE ARCTIC COLD FRONT WILL PLAY A BIG ROLE AS IT IS PROGGED TO DROP RIGHT BACK SOUTH ACROSS THE CWA OVER THE COURSE OF THE DAY...ALTHOUGH THE GFS IS MUCH MORE AGGRESSIVE THAN THE LATEST ECMWF/NAM REGARDING WITH THIS COLD PUSH. CONSENSUS OF SEVERAL MODELS/GUIDANCE WAS TO...YOU GUESSED IT...LOWER TEMPS SEVERAL DEGREES...AND BUMPED DOWN 3-5 DEGREES MOST AREAS...NOW ADVERTISING MID 20S NORTHEAST TO UPPER 30S SOUTHWEST. INTERESTING TO NOTE THAT THIS DAY HAS NOW TRENDED 15+ DEGREES COLDER THAN FORECASTS ISSUED JUST 2-3 DAYS AGO. FRIDAY NIGHT...IT REMAINS DRY AS A SURFACE RIDGE AXIS SLIDES ACROSS THE CENTRAL PLAINS...AND A BRIEF BIT OF SHORTWAVE RIDGING SETS IN ALOFT. ASSUMING LIMITED CLOUD COVER...TEMPS COULD TAKE A DECENT TUMBLE...AND LOWERED LOWS 5 DEGREES MOST AREAS WITH SINGLE DIGITS ABOVE ZERO NOW IN PLACE FOR MUCH OF THE CWA. SATURDAY...THE NEXT...MORE VIGOROUS MID LEVEL WAVE STARTS MAKING ITS WAY ACROSS THE CENTRAL/SOUTHERN ROCKIES...INDUCING SURFACE PRESSURE FALLS AND RAMPING UP SOUTH-SOUTHEAST BREEZES INTO AT LEAST THE 15-20 MPH SUSTAINED RANGE. DESPITE THIS SOUTHERLY WIND...THE DIRECTION IS NOT OVERLY CONDUCIVE FOR SIGNIFICANT WARMING...AND HAVE ONLY INDICATED A MODEST WARM-UP OVER FRIDAY...WITH HIGHS RANGING FROM LOW 30S FAR EAST TO LOW 40S FAR WEST. SATURDAY NIGHT...LEFT THIS PERIOD DRY...AT LEAST FOR NOW...AS THE INCOMING SHORTWAVE CONTINUES TO AMPLIFY/STRENGTHEN AS A 100+KT UPPER JET STARTS TO ROUND THE BASE INTO THE CENTRAL PLAINS. ONLY THING KEEPING POPS FROM BEING INSERTED AT THIS POINT IS SUGGESTION THAT A MID LEVEL DRY SLOT WILL BE IN PLACE ACROSS THE CWA...WITH MAIN FORCING/MID LEVEL DEFORMATION AXIS HOLDING JUST OFF TO THE NORTH/WEST...THUS HOLDING OFF BETTER PRECIP CHANCES UNTIL SUNDAY AS DISCUSSED BELOW. LONG TERM...SUNDAY THROUGH WEDNESDAY. PATTERN REMAINS PROGRESSIVE THROUGH THE EXTENDED PERIODS WITH CHALLENGE OF TRYING TO TIME WAVES. BEGINNING ON SUNDAY...A 100+KT JET NOSES EAST FM THE FOUR CORNERS REGION AND LIFTS NORTHEAST ACROSS THE CENTRAL PLAINS DEEPENING THE MID/UPPER TROUGH ACROSS THE CENTRAL PLAINS. THE 00Z ECMWF IS THE STRONGEST/SLOWEST WITH THE SYSTEM ON SUNDAY AND CLOSES OFF THE H7 LOW...WHEREAS OTHER EXTENDED MODELS SUGGEST A MORE PROGRESSIVE OPEN WAVE. IN GENERAL...THERE IS CONSENSUS AMONG MODELS THAT OUR REGION WILL BE UNDER THE INFLUENCE OF A TROUGH THRU AT LEAST THE FIRST HALF OF THE DAY...OR LONGER IF SLOWER ECWMF VERIFIES. COOL FRONTAL BOUNDARY WILL SWEEP ACROSS OUR REGION IN MORNING WITH AN AREA OF LOW CLOUDS/PCPN ACCOMPANYING SYSTEM AIDED BY ENHANCED UPPER DYNAMICS IN LFQ OF JET. HOW LONG PCPN/LOW CLOUDS LINGERS IS DEPENDENT ON STRENGTH OF SYSTEM AND IF SYSTEM MOVES THRU FASTER...CLEARING SKIES/DOWNSLOPE CONDITIONS MAY AID IN SOME WARMING FOR THE AFTN. IN ADDITION TO THE PCPN POTENTIAL...MODELS ALSO SUGGEST STRONG WIND POTENTIAL SUNDAY WITH NAM INDICATING 3HR PRESSURE RISES OF 6MB BEHIND THE FRONT IN TIGHTENING SFC GRADIENT...WHILE A CORRIDOR OF 50 TO 60KT MID LEVEL WINDS CROSS OUR REGION. WILL NEED TO MONITOR MODEL TRENDS OF THIS AS WELL. FOR PCPN TYPE ON SUNDAY...HAVE WENT WITH R/S IN THE MORNING TRANSITIONING TO RAIN IN AFTN AS TEMPS LOOK TO RISE ABOVE FREEZING. HEADING INTO SUNDAY NIGHT...THE TROUGH AXIS DEPARTS AND CONDITIONS DRY WITH RISING HEIGHTS BEHIND THE EXITING SYSTEM. MODELS ARE STILL LOOKING DRY MONDAY IN BETWEEN SYSTEMS...AND THEN NEXT WAVE IS PROGGED TO EMERGE ONTO THE PLAINS ON TUESDAY. THERE IS STILL SOME UNCERTAINTY ON DEGREE OF MOISTURE WITH THIS NEXT SYSTEM BUT SMALL CHCS FOR PCPN STILL WARRANTED AS CURRENTLY FORECAST. MILD AIRMASS IN PLACE SHLD MAINTAIN LIQUID CHCS INITIALLY WITH POTENTIAL FOR CHANGE TO SNOW IN COOLER AIR WITH FROPA TUESDAY NIGHT. THE AIRMASS IN GENERAL DURING THE EXTENDED IS NOT OVERLY COLD AND TEMPS LOOK TO BE MORE DEPENDENT ON CLOUDS/PCPN. && .GID WATCHES/WARNINGS/ADVISORIES... NE...NONE. KS...NONE. && $$
AREA FORECAST DISCUSSION
NWS HASTINGS NE
1027 AM CST THU JAN 19 2012 .UPDATE...SENT A QUICK UPDATE TO ADJUST THE HOURLY TEMPERATURE CURVE TO BETTER REFLECT REALITY...OTHERWISE THE REMAINDER OF THE FORECAST LOOKS ON TRACK FOR TODAY. && .PREV DISCUSSION... /ISSUED 639 AM CST THU JAN 19 2012/ UPDATE...JUST RAN A QUICK UPDATE TO TABULAR AFM/PFM PRODUCTS AND WEB-BASED PRODUCTS TO BRING NEXT SEVERAL HOURS OF TEMP/DEWPOINT TRENDS MORE IN LINE WITH CURRENT OBS...AS COLDER AND DRIER AIR HAS PUSHED MORE AGGRESSIVELY SOUTHWARD INTO SOUTHERN PORTIONS OF THE CWA THAN EXPECTED EVEN A FEW HOURS AGO. ONLY MODEL/GUIDANCE REALLY PROVING USEFUL FOR THESE VERY SHORT TERM TRENDS IS GFS LAMP GUIDANCE. WIND CHILLS BETWEEN -10 AND -15 WILL BE WIDESPREAD ACROSS MOST ALL NEB ZONES FOR THE NEXT FEW HOURS...WITH KS ZONES MORE SO -5 TO -10. ALTHOUGH NO CHANGES WERE MADE TO AFTERNOON HIGH TEMPS AT THIS TIME...INTERESTING TO NOTE THAT BOTH THE 09Z RUC AND HRRR SUGGEST THAT THE TRI-CITIES WILL RECOVER ENOUGH TO POSSIBLY REACH 20 THIS AFTERNOON...BUT THIS SEEMS TOO OPTIMISTIC AT THIS TIME AND WILL STICK WITH GOING FORECAST. PREV DISCUSSION... /ISSUED 600 AM CST THU JAN 19 2012/ AVIATION...12Z TAF. ARCTIC HIGH PRESSURE WILL SHIFT INTO NORTHERN IOWA TODAY. NORTHEASTERLY WINDS THIS MORNING WILL BECOME VARIABLE FOR A FEW HOURS AROUND MIDDAY BEFORE TRANSITIONING TO THE SOUTHEAST. CLOUD COVER LOOKS TO BE LIMITED TO THE MID AND HIGH LEVELS FOR MUCH OF THE DAY WITH SOME MVFR TO VFR CIGS POSSIBLE LATER TONIGHT OR TOWARD FRIDAY MORNING. PREV DISCUSSION... /ISSUED 451 AM CST THU JAN 19 2012/ SHORT TERM...THROUGH SATURDAY NIGHT. PRIMARY CONCERN DURING THE NEXT 72 HOURS CONTINUES TO BE TEMPERATURE TRENDS...WITH THE NEXT REGIONAL SNOW EVENT FROM THURSDAY NIGHT INTO FRIDAY STILL PROGGED TO MISS MOST...IF NOT ALL OF THE CWA TO THE NORTHEAST...FOCUSING ALONG AN AXIS FROM SD THROUGH NORTHEAST NEB/NORTHERN IA. THAT BEING SAID...ALTHOUGH NOT OVERLY CONCERNED AT THIS POINT...WILL NEED TO MONITOR LOW LEVEL MOISTURE TRENDS CLOSELY LATE THURS NIGHT INTO FRIDAY MORNING TO MAKE SURE THAT NO LIGHT FREEZING DRIZZLE TRIES TO SNEAK UP ON US. 09Z OBJECTIVE SURFACE ANALYSIS REVEALS THAT THE WELL ADVERTISED ARCTIC COLD FRONT HAS MADE STEADY PROGRESS SOUTHWARD ACROSS THE CWA THROUGH THE NIGHT...PUSHED ALONG BY A BROAD 1024MB HIGH CENTERED FROM MT TO NORTHERN SD. TEMPERATURES AT 09Z RANGED FROM 2 AT ORD...TO 18 AT BELOIT. ADDING TO THE INVADING BITTERNESS ARE STEADY NORTH-NORTHEAST BREEZES OF 10-20 MPH...YIELDING WIND CHILL VALUES RANGING FROM -10 TO -15 NORTH OF I-80...TO NEAR ZERO IN THE SOUTH. DESPITE PLENTIFUL MID LEVEL RADAR RETURNS EARLIER THE NIGHT ACROSS THE NORTHEAST...IT IS LIKELY THAT FLURRY ACTIVITY DID NOT MATERIALIZE ACROSS THE NORTHEAST. ALOFT...WATER VAPOR IMAGERY AND SHORT TERM MODEL DATA FEATURE VERY FAST NORTHWEST FLOW BISECTING THE CONUS FROM NORTHWEST TO SOUTHEAST...HIGHLIGHTED BY A 140+KT 300MB JET STREAK CUTTING ACROSS EASTERN NEB. ALTHOUGH THE PRIMARY MID LEVEL SHORTWAVE/500MB VORT MAX OF NOTE IS ALREADY WELL NORTHEAST INTO THE GREAT LAKES...LIFT ASSOCIATED WITH THE UPPER JET STREAK HAS GENERATED PLENTIFUL CIRRUS OVER MAINLY NEB ZONES OVERNIGHT...BUT KEEPING PRIMARY ZONE OF MID LEVEL SATURATION/POSSIBLE LIGHT SNOW PRODUCTION OFF TO THE NORTH AND EAST. TODAY...THE AFOREMENTIONED STRONG UPPER JET AXIS DRIFTS NORTHEAST...WITH ITS CENTER ALONG AN AXIS FROM CENTRAL ND TO NORTHERN IL BY 00Z THIS EVENING. AS A RESULT...THE EXTENSIVE HIGH LEVEL CLOUD COVER ACROSS MOST OF THE CWA SHOULD GRADUALLY SCATTER OUT AND/OR LIFT NORTHEAST AS WELL...WITH AT LEAST PARTLY CLOUDY SKIES ANTICIPATED MOST AREAS FOR THIS AFTERNOON. EVEN IF THE SUN IS OUT...IT WON/T DO A WHOLE LOT TO MASK WHAT IS ALMOST CERTAINLY TO BE THE OVERALL COLDEST DAY OF THE WINTER SO FAR FOR MOST OF THE CWA. AS THE DAY WEARS ON...THE CENTER OF THE SURFACE HIGH WILL MIGRATE INTO MN/IA...ALLOWING BREEZES TO GRADUALLY DIMINISH INTO THE 5-10 MPH RANGE FOR THIS AFTERNOON AS THEY GRADUALLY SHIFT FROM MORE NORTHERLY TO MORE EASTERLY/SOUTHEASTERLY BY LATE IN THE DAY. AS FOR TEMPS...YET AGAIN OPTED TO LOWER HIGHS BY 2-5 DEGREES FROM PREVIOUS FORECAST IN MOST AREAS...LEANING TOWARD THE COLDER MAV GUIDANCE. THIS YIELDS HIGHS RANGING FROM ONLY 10-13 DEGREES IN THE NORTHEAST CWA...TO MID 20S FAR SOUTH AND WEST WHERE THE SOUTHEAST FLOW AROUND THE HIGH SHOULD HELP MODERATE THINGS SOMEWHAT. AS FOR WIND CHILLS THIS MORNING...VALUES WILL CONTINUE TO RANGE BETWEEN -10 AND -17 ACROSS MUCH OF THE NORTHEAST 1/2 OF THE CWA THROUGH AT LEAST MID-MORNING...WHICH WILL BE ABOVE ADVISORY CRITERIA OF -20 BUT NOT BY MUCH. ITS CLOSE ENOUGH THAT WILL PUT A MENTION IN THE HAZARDOUS WEATHER OUTLOOK. TONIGHT...THE NEXT BATCH OF BROAD...LOW AMPLITUDE SHORTWAVE ENERGY QUICKLY APPROACHES THE CENTRAL CONUS FROM THE NORTHWEST. WITHIN THE ENTRANCE REGION OF THE PRIMARY UPPER JET AXIS MIGRATING ACROSS THE UPPER MISS VALLEY/GREAT LAKES...AN IMPRESSIVE ZONE OF ISENTROPIC LIFT/MID LEVEL CONVERGENCE WILL SET UP ALONG AND NORTH OF THE PRIMARY LOW-MID LEVEL TEMPERATURE GRADIENT CENTERED FROM SD INTO NORTHEAST NEB/IA. THIS WILL BE THE OBVIOUS FOCUS FOR THE START OF A MEASURABLE SNOW EVENT FOR THOSE AREAS. ALTHOUGH IT IS SEEMING MORE AND MORE LIKELY THAT THE CWA WILL MISS OUT ON THIS ACTION...PREVIOUS FORECAST HAD SOME LOW POPS ACROSS THE NORTHEAST...AND WILL CONTINUE THIS MENTION AFTER MIDNIGHT FOR MAINLY THE NORTHEAST 1/5 OF THE CWA JUST IN CASE THE FAR SOUTHERN EDGE OF THIS ACTIVITY SLIPS IN. ANY ACCUMULATIONS...IF ANY...WOULD NOT AMOUNT TO MORE THAN A FEW TENTHS. INTERESTINGLY...IF ANYTHING DOES HAPPEN TO FALL IN THE FAR NORTH TONIGHT...IT MIGHT ACTUALLY FAVOR THE FORM OF LIGHT SLEET BASED ON FORECAST SOUNDINGS...BUT WILL LEAVE IT AS SNOW MENTION FOR NOW. HAVE ALSO BEEN GROWING A BIT LEARY OF POSSIBLE LIGHT FREEZING DRIZZLE ACROSS NORTHERN PORTIONS OF THE AREA GIVEN THE GOOD LOW LEVEL WARM ADVECTION...BUT THINKING AT THIS POINT IS THAT ANY POTENTIAL STRATUS LAYER WOULD BE TOO SHALLOW TO SUPPORT THIS. SOMETHING TO WATCH. AS FOR LOW TEMPS...CHANGED THEM LITTLE...ALTHOUGH CONFIDENCE IN HOURLY TRENDS IS QUITE LOW AS TEMPS COULD EASILY DISPLAY STEADY/SLOWLY RISING CHARACTERISTICS AS BREEZES TURN SOUTHERLY. KEPT IT SIMPLE FOR NOW THOUGH...INDICATING MOST AREAS BOTTOMING OUT BETWEEN 9 AND 15 DEGREES...ALTHOUGH THIS MIGHT END UP BEING EARLIER IN THE NIGHT VERSUS LATER FOR SOME PLACES. FRIDAY...THE MAIN BATCH OF SHORTWAVE ENERGY PASSES THROUGH THE CENTRAL PLAINS...ALTHOUGH THE UPPER JET FORCING CONTINUES TO DIRECT THE MAIN PRECIP EVENT FROM EASTERN SD INTO NORTHERN IA/SOUTHERN MN AND POINTS EAST. THUS LEFT PRECIP MENTION OUT OF THE FORECAST...ALTHOUGH ONCE AGAIN WILL HAVE TO MONITOR DEPTH OF POSSIBLE STRATUS LAYER CLOSELY FOR OUTSIDE CHANCE OF SNEAKY LIGHT FREEZING DRIZZLE THREAT...BUT JUST SEEMS RATHER UNLIKELY AT THIS JUNCTURE. AS FOR HIGH TEMPS...THE SOUTHERN EDGE OF THE ARCTIC COLD FRONT WILL PLAY A BIG ROLE AS IT IS PROGGED TO DROP RIGHT BACK SOUTH ACROSS THE CWA OVER THE COURSE OF THE DAY...ALTHOUGH THE GFS IS MUCH MORE AGGRESSIVE THAN THE LATEST ECMWF/NAM REGARDING WITH THIS COLD PUSH. CONSENSUS OF SEVERAL MODELS/GUIDANCE WAS TO...YOU GUESSED IT...LOWER TEMPS SEVERAL DEGREES...AND BUMPED DOWN 3-5 DEGREES MOST AREAS...NOW ADVERTISING MID 20S NORTHEAST TO UPPER 30S SOUTHWEST. INTERESTING TO NOTE THAT THIS DAY HAS NOW TRENDED 15+ DEGREES COLDER THAN FORECASTS ISSUED JUST 2-3 DAYS AGO. FRIDAY NIGHT...IT REMAINS DRY AS A SURFACE RIDGE AXIS SLIDES ACROSS THE CENTRAL PLAINS...AND A BRIEF BIT OF SHORTWAVE RIDGING SETS IN ALOFT. ASSUMING LIMITED CLOUD COVER...TEMPS COULD TAKE A DECENT TUMBLE...AND LOWERED LOWS 5 DEGREES MOST AREAS WITH SINGLE DIGITS ABOVE ZERO NOW IN PLACE FOR MUCH OF THE CWA. SATURDAY...THE NEXT...MORE VIGOROUS MID LEVEL WAVE STARTS MAKING ITS WAY ACROSS THE CENTRAL/SOUTHERN ROCKIES...INDUCING SURFACE PRESSURE FALLS AND RAMPING UP SOUTH-SOUTHEAST BREEZES INTO AT LEAST THE 15-20 MPH SUSTAINED RANGE. DESPITE THIS SOUTHERLY WIND...THE DIRECTION IS NOT OVERLY CONDUCIVE FOR SIGNIFICANT WARMING...AND HAVE ONLY INDICATED A MODEST WARM-UP OVER FRIDAY...WITH HIGHS RANGING FROM LOW 30S FAR EAST TO LOW 40S FAR WEST. SATURDAY NIGHT...LEFT THIS PERIOD DRY...AT LEAST FOR NOW...AS THE INCOMING SHORTWAVE CONTINUES TO AMPLIFY/STRENGTHEN AS A 100+KT UPPER JET STARTS TO ROUND THE BASE INTO THE CENTRAL PLAINS. ONLY THING KEEPING POPS FROM BEING INSERTED AT THIS POINT IS SUGGESTION THAT A MID LEVEL DRY SLOT WILL BE IN PLACE ACROSS THE CWA...WITH MAIN FORCING/MID LEVEL DEFORMATION AXIS HOLDING JUST OFF TO THE NORTH/WEST...THUS HOLDING OFF BETTER PRECIP CHANCES UNTIL SUNDAY AS DISCUSSED BELOW. LONG TERM...SUNDAY THROUGH WEDNESDAY. PATTERN REMAINS PROGRESSIVE THROUGH THE EXTENDED PERIODS WITH CHALLENGE OF TRYING TO TIME WAVES. BEGINNING ON SUNDAY...A 100+KT JET NOSES EAST FM THE FOUR CORNERS REGION AND LIFTS NORTHEAST ACROSS THE CENTRAL PLAINS DEEPENING THE MID/UPPER TROUGH ACROSS THE CENTRAL PLAINS. THE 00Z ECMWF IS THE STRONGEST/SLOWEST WITH THE SYSTEM ON SUNDAY AND CLOSES OFF THE H7 LOW...WHEREAS OTHER EXTENDED MODELS SUGGEST A MORE PROGRESSIVE OPEN WAVE. IN GENERAL...THERE IS CONSENSUS AMONG MODELS THAT OUR REGION WILL BE UNDER THE INFLUENCE OF A TROUGH THRU AT LEAST THE FIRST HALF OF THE DAY...OR LONGER IF SLOWER ECWMF VERIFIES. COOL FRONTAL BOUNDARY WILL SWEEP ACROSS OUR REGION IN MORNING WITH AN AREA OF LOW CLOUDS/PCPN ACCOMPANYING SYSTEM AIDED BY ENHANCED UPPER DYNAMICS IN LFQ OF JET. HOW LONG PCPN/LOW CLOUDS LINGERS IS DEPENDENT ON STRENGTH OF SYSTEM AND IF SYSTEM MOVES THRU FASTER...CLEARING SKIES/DOWNSLOPE CONDITIONS MAY AID IN SOME WARMING FOR THE AFTN. IN ADDITION TO THE PCPN POTENTIAL...MODELS ALSO SUGGEST STRONG WIND POTENTIAL SUNDAY WITH NAM INDICATING 3HR PRESSURE RISES OF 6MB BEHIND THE FRONT IN TIGHTENING SFC GRADIENT...WHILE A CORRIDOR OF 50 TO 60KT MID LEVEL WINDS CROSS OUR REGION. WILL NEED TO MONITOR MODEL TRENDS OF THIS AS WELL. FOR PCPN TYPE ON SUNDAY...HAVE WENT WITH R/S IN THE MORNING TRANSITIONING TO RAIN IN AFTN AS TEMPS LOOK TO RISE ABOVE FREEZING. HEADING INTO SUNDAY NIGHT...THE TROUGH AXIS DEPARTS AND CONDITIONS DRY WITH RISING HEIGHTS BEHIND THE EXITING SYSTEM. MODELS ARE STILL LOOKING DRY MONDAY IN BETWEEN SYSTEMS...AND THEN NEXT WAVE IS PROGGED TO EMERGE ONTO THE PLAINS ON TUESDAY. THERE IS STILL SOME UNCERTAINTY ON DEGREE OF MOISTURE WITH THIS NEXT SYSTEM BUT SMALL CHCS FOR PCPN STILL WARRANTED AS CURRENTLY FORECAST. MILD AIRMASS IN PLACE SHLD MAINTAIN LIQUID CHCS INITIALLY WITH POTENTIAL FOR CHANGE TO SNOW IN COOLER AIR WITH FROPA TUESDAY NIGHT. THE AIRMASS IN GENERAL DURING THE EXTENDED IS NOT OVERLY COLD AND TEMPS LOOK TO BE MORE DEPENDENT ON CLOUDS/PCPN. && .GID WATCHES/WARNINGS/ADVISORIES... NE...NONE. KS...NONE. && $$
AREA FORECAST DISCUSSION
NWS HASTINGS NE
639 AM CST THU JAN 19 2012 .UPDATE...JUST RAN A QUICK UPDATE TO TABULAR AFM/PFM PRODUCTS AND WEB-BASED PRODUCTS TO BRING NEXT SEVERAL HOURS OF TEMP/DEWPOINT TRENDS MORE IN LINE WITH CURRENT OBS...AS COLDER AND DRIER AIR HAS PUSHED MORE AGGRESSIVELY SOUTHWARD INTO SOUTHERN PORTIONS OF THE CWA THAN EXPECTED EVEN A FEW HOURS AGO. ONLY MODEL/GUIDANCE REALLY PROVING USEFUL FOR THESE VERY SHORT TERM TRENDS IS GFS LAMP GUIDANCE. WIND CHILLS BETWEEN -10 AND -15 WILL BE WIDESPREAD ACROSS MOST ALL NEB ZONES FOR THE NEXT FEW HOURS...WITH KS ZONES MORE SO -5 TO -10. ALTHOUGH NO CHANGES WERE MADE TO AFTERNOON HIGH TEMPS AT THIS TIME...INTERESTING TO NOTE THAT BOTH THE 09Z RUC AND HRRR SUGGEST THAT THE TRI-CITIES WILL RECOVER ENOUGH TO POSSIBLY REACH 20 THIS AFTERNOON...BUT THIS SEEMS TOO OPTIMISTIC AT THIS TIME AND WILL STICK WITH GOING FORECAST. && .PREV DISCUSSION... /ISSUED 600 AM CST THU JAN 19 2012/ AVIATION...12Z TAF. ARCTIC HIGH PRESSURE WILL SHIFT INTO NORTHERN IOWA TODAY. NORTHEASTERLY WINDS THIS MORNING WILL BECOME VARIABLE FOR A FEW HOURS AROUND MIDDAY BEFORE TRANSITIONING TO THE SOUTHEAST. CLOUD COVER LOOKS TO BE LIMITED TO THE MID AND HIGH LEVELS FOR MUCH OF THE DAY WITH SOME MVFR TO VFR CIGS POSSIBLE LATER TONIGHT OR TOWARD FRIDAY MORNING. PREV DISCUSSION... /ISSUED 451 AM CST THU JAN 19 2012/ SHORT TERM...THROUGH SATURDAY NIGHT. PRIMARY CONCERN DURING THE NEXT 72 HOURS CONTINUES TO BE TEMPERATURE TRENDS...WITH THE NEXT REGIONAL SNOW EVENT FROM THURSDAY NIGHT INTO FRIDAY STILL PROGGED TO MISS MOST...IF NOT ALL OF THE CWA TO THE NORTHEAST...FOCUSING ALONG AN AXIS FROM SD THROUGH NORTHEAST NEB/NORTHERN IA. THAT BEING SAID...ALTHOUGH NOT OVERLY CONCERNED AT THIS POINT...WILL NEED TO MONITOR LOW LEVEL MOISTURE TRENDS CLOSELY LATE THURS NIGHT INTO FRIDAY MORNING TO MAKE SURE THAT NO LIGHT FREEZING DRIZZLE TRIES TO SNEAK UP ON US. 09Z OBJECTIVE SURFACE ANALYSIS REVEALS THAT THE WELL ADVERTISED ARCTIC COLD FRONT HAS MADE STEADY PROGRESS SOUTHWARD ACROSS THE CWA THROUGH THE NIGHT...PUSHED ALONG BY A BROAD 1024MB HIGH CENTERED FROM MT TO NORTHERN SD. TEMPERATURES AT 09Z RANGED FROM 2 AT ORD...TO 18 AT BELOIT. ADDING TO THE INVADING BITTERNESS ARE STEADY NORTH-NORTHEAST BREEZES OF 10-20 MPH...YIELDING WIND CHILL VALUES RANGING FROM -10 TO -15 NORTH OF I-80...TO NEAR ZERO IN THE SOUTH. DESPITE PLENTIFUL MID LEVEL RADAR RETURNS EARLIER THE NIGHT ACROSS THE NORTHEAST...IT IS LIKELY THAT FLURRY ACTIVITY DID NOT MATERIALIZE ACROSS THE NORTHEAST. ALOFT...WATER VAPOR IMAGERY AND SHORT TERM MODEL DATA FEATURE VERY FAST NORTHWEST FLOW BISECTING THE CONUS FROM NORTHWEST TO SOUTHEAST...HIGHLIGHTED BY A 140+KT 300MB JET STREAK CUTTING ACROSS EASTERN NEB. ALTHOUGH THE PRIMARY MID LEVEL SHORTWAVE/500MB VORT MAX OF NOTE IS ALREADY WELL NORTHEAST INTO THE GREAT LAKES...LIFT ASSOCIATED WITH THE UPPER JET STREAK HAS GENERATED PLENTIFUL CIRRUS OVER MAINLY NEB ZONES OVERNIGHT...BUT KEEPING PRIMARY ZONE OF MID LEVEL SATURATION/POSSIBLE LIGHT SNOW PRODUCTION OFF TO THE NORTH AND EAST. TODAY...THE AFOREMENTIONED STRONG UPPER JET AXIS DRIFTS NORTHEAST...WITH ITS CENTER ALONG AN AXIS FROM CENTRAL ND TO NORTHERN IL BY 00Z THIS EVENING. AS A RESULT...THE EXTENSIVE HIGH LEVEL CLOUD COVER ACROSS MOST OF THE CWA SHOULD GRADUALLY SCATTER OUT AND/OR LIFT NORTHEAST AS WELL...WITH AT LEAST PARTLY CLOUDY SKIES ANTICIPATED MOST AREAS FOR THIS AFTERNOON. EVEN IF THE SUN IS OUT...IT WON/T DO A WHOLE LOT TO MASK WHAT IS ALMOST CERTAINLY TO BE THE OVERALL COLDEST DAY OF THE WINTER SO FAR FOR MOST OF THE CWA. AS THE DAY WEARS ON...THE CENTER OF THE SURFACE HIGH WILL MIGRATE INTO MN/IA...ALLOWING BREEZES TO GRADUALLY DIMINISH INTO THE 5-10 MPH RANGE FOR THIS AFTERNOON AS THEY GRADUALLY SHIFT FROM MORE NORTHERLY TO MORE EASTERLY/SOUTHEASTERLY BY LATE IN THE DAY. AS FOR TEMPS...YET AGAIN OPTED TO LOWER HIGHS BY 2-5 DEGREES FROM PREVIOUS FORECAST IN MOST AREAS...LEANING TOWARD THE COLDER MAV GUIDANCE. THIS YIELDS HIGHS RANGING FROM ONLY 10-13 DEGREES IN THE NORTHEAST CWA...TO MID 20S FAR SOUTH AND WEST WHERE THE SOUTHEAST FLOW AROUND THE HIGH SHOULD HELP MODERATE THINGS SOMEWHAT. AS FOR WIND CHILLS THIS MORNING...VALUES WILL CONTINUE TO RANGE BETWEEN -10 AND -17 ACROSS MUCH OF THE NORTHEAST 1/2 OF THE CWA THROUGH AT LEAST MID-MORNING...WHICH WILL BE ABOVE ADVISORY CRITERIA OF -20 BUT NOT BY MUCH. ITS CLOSE ENOUGH THAT WILL PUT A MENTION IN THE HAZARDOUS WEATHER OUTLOOK. TONIGHT...THE NEXT BATCH OF BROAD...LOW AMPLITUDE SHORTWAVE ENERGY QUICKLY APPROACHES THE CENTRAL CONUS FROM THE NORTHWEST. WITHIN THE ENTRANCE REGION OF THE PRIMARY UPPER JET AXIS MIGRATING ACROSS THE UPPER MISS VALLEY/GREAT LAKES...AN IMPRESSIVE ZONE OF ISENTROPIC LIFT/MID LEVEL CONVERGENCE WILL SET UP ALONG AND NORTH OF THE PRIMARY LOW-MID LEVEL TEMPERATURE GRADIENT CENTERED FROM SD INTO NORTHEAST NEB/IA. THIS WILL BE THE OBVIOUS FOCUS FOR THE START OF A MEASURABLE SNOW EVENT FOR THOSE AREAS. ALTHOUGH IT IS SEEMING MORE AND MORE LIKELY THAT THE CWA WILL MISS OUT ON THIS ACTION...PREVIOUS FORECAST HAD SOME LOW POPS ACROSS THE NORTHEAST...AND WILL CONTINUE THIS MENTION AFTER MIDNIGHT FOR MAINLY THE NORTHEAST 1/5 OF THE CWA JUST IN CASE THE FAR SOUTHERN EDGE OF THIS ACTIVITY SLIPS IN. ANY ACCUMULATIONS...IF ANY...WOULD NOT AMOUNT TO MORE THAN A FEW TENTHS. INTERESTINGLY...IF ANYTHING DOES HAPPEN TO FALL IN THE FAR NORTH TONIGHT...IT MIGHT ACTUALLY FAVOR THE FORM OF LIGHT SLEET BASED ON FORECAST SOUNDINGS...BUT WILL LEAVE IT AS SNOW MENTION FOR NOW. HAVE ALSO BEEN GROWING A BIT LEARY OF POSSIBLE LIGHT FREEZING DRIZZLE ACROSS NORTHERN PORTIONS OF THE AREA GIVEN THE GOOD LOW LEVEL WARM ADVECTION...BUT THINKING AT THIS POINT IS THAT ANY POTENTIAL STRATUS LAYER WOULD BE TOO SHALLOW TO SUPPORT THIS. SOMETHING TO WATCH. AS FOR LOW TEMPS...CHANGED THEM LITTLE...ALTHOUGH CONFIDENCE IN HOURLY TRENDS IS QUITE LOW AS TEMPS COULD EASILY DISPLAY STEADY/SLOWLY RISING CHARACTERISTICS AS BREEZES TURN SOUTHERLY. KEPT IT SIMPLE FOR NOW THOUGH...INDICATING MOST AREAS BOTTOMING OUT BETWEEN 9 AND 15 DEGREES...ALTHOUGH THIS MIGHT END UP BEING EARLIER IN THE NIGHT VERSUS LATER FOR SOME PLACES. FRIDAY...THE MAIN BATCH OF SHORTWAVE ENERGY PASSES THROUGH THE CENTRAL PLAINS...ALTHOUGH THE UPPER JET FORCING CONTINUES TO DIRECT THE MAIN PRECIP EVENT FROM EASTERN SD INTO NORTHERN IA/SOUTHERN MN AND POINTS EAST. THUS LEFT PRECIP MENTION OUT OF THE FORECAST...ALTHOUGH ONCE AGAIN WILL HAVE TO MONITOR DEPTH OF POSSIBLE STRATUS LAYER CLOSELY FOR OUTSIDE CHANCE OF SNEAKY LIGHT FREEZING DRIZZLE THREAT...BUT JUST SEEMS RATHER UNLIKELY AT THIS JUNCTURE. AS FOR HIGH TEMPS...THE SOUTHERN EDGE OF THE ARCTIC COLD FRONT WILL PLAY A BIG ROLE AS IT IS PROGGED TO DROP RIGHT BACK SOUTH ACROSS THE CWA OVER THE COURSE OF THE DAY...ALTHOUGH THE GFS IS MUCH MORE AGGRESSIVE THAN THE LATEST ECMWF/NAM REGARDING WITH THIS COLD PUSH. CONSENSUS OF SEVERAL MODELS/GUIDANCE WAS TO...YOU GUESSED IT...LOWER TEMPS SEVERAL DEGREES...AND BUMPED DOWN 3-5 DEGREES MOST AREAS...NOW ADVERTISING MID 20S NORTHEAST TO UPPER 30S SOUTHWEST. INTERESTING TO NOTE THAT THIS DAY HAS NOW TRENDED 15+ DEGREES COLDER THAN FORECASTS ISSUED JUST 2-3 DAYS AGO. FRIDAY NIGHT...IT REMAINS DRY AS A SURFACE RIDGE AXIS SLIDES ACROSS THE CENTRAL PLAINS...AND A BRIEF BIT OF SHORTWAVE RIDGING SETS IN ALOFT. ASSUMING LIMITED CLOUD COVER...TEMPS COULD TAKE A DECENT TUMBLE...AND LOWERED LOWS 5 DEGREES MOST AREAS WITH SINGLE DIGITS ABOVE ZERO NOW IN PLACE FOR MUCH OF THE CWA. SATURDAY...THE NEXT...MORE VIGOROUS MID LEVEL WAVE STARTS MAKING ITS WAY ACROSS THE CENTRAL/SOUTHERN ROCKIES...INDUCING SURFACE PRESSURE FALLS AND RAMPING UP SOUTH-SOUTHEAST BREEZES INTO AT LEAST THE 15-20 MPH SUSTAINED RANGE. DESPITE THIS SOUTHERLY WIND...THE DIRECTION IS NOT OVERLY CONDUCIVE FOR SIGNIFICANT WARMING...AND HAVE ONLY INDICATED A MODEST WARM-UP OVER FRIDAY...WITH HIGHS RANGING FROM LOW 30S FAR EAST TO LOW 40S FAR WEST. SATURDAY NIGHT...LEFT THIS PERIOD DRY...AT LEAST FOR NOW...AS THE INCOMING SHORTWAVE CONTINUES TO AMPLIFY/STRENGTHEN AS A 100+KT UPPER JET STARTS TO ROUND THE BASE INTO THE CENTRAL PLAINS. ONLY THING KEEPING POPS FROM BEING INSERTED AT THIS POINT IS SUGGESTION THAT A MID LEVEL DRY SLOT WILL BE IN PLACE ACROSS THE CWA...WITH MAIN FORCING/MID LEVEL DEFORMATION AXIS HOLDING JUST OFF TO THE NORTH/WEST...THUS HOLDING OFF BETTER PRECIP CHANCES UNTIL SUNDAY AS DISCUSSED BELOW. LONG TERM...SUNDAY THROUGH WEDNESDAY. PATTERN REMAINS PROGRESSIVE THROUGH THE EXTENDED PERIODS WITH CHALLENGE OF TRYING TO TIME WAVES. BEGINNING ON SUNDAY...A 100+KT JET NOSES EAST FM THE FOUR CORNERS REGION AND LIFTS NORTHEAST ACROSS THE CENTRAL PLAINS DEEPENING THE MID/UPPER TROUGH ACROSS THE CENTRAL PLAINS. THE 00Z ECMWF IS THE STRONGEST/SLOWEST WITH THE SYSTEM ON SUNDAY AND CLOSES OFF THE H7 LOW...WHEREAS OTHER EXTENDED MODELS SUGGEST A MORE PROGRESSIVE OPEN WAVE. IN GENERAL...THERE IS CONSENSUS AMONG MODELS THAT OUR REGION WILL BE UNDER THE INFLUENCE OF A TROUGH THRU AT LEAST THE FIRST HALF OF THE DAY...OR LONGER IF SLOWER ECWMF VERIFIES. COOL FRONTAL BOUNDARY WILL SWEEP ACROSS OUR REGION IN MORNING WITH AN AREA OF LOW CLOUDS/PCPN ACCOMPANYING SYSTEM AIDED BY ENHANCED UPPER DYNAMICS IN LFQ OF JET. HOW LONG PCPN/LOW CLOUDS LINGERS IS DEPENDENT ON STRENGTH OF SYSTEM AND IF SYSTEM MOVES THRU FASTER...CLEARING SKIES/DOWNSLOPE CONDITIONS MAY AID IN SOME WARMING FOR THE AFTN. IN ADDITION TO THE PCPN POTENTIAL...MODELS ALSO SUGGEST STRONG WIND POTENTIAL SUNDAY WITH NAM INDICATING 3HR PRESSURE RISES OF 6MB BEHIND THE FRONT IN TIGHTENING SFC GRADIENT...WHILE A CORRIDOR OF 50 TO 60KT MID LEVEL WINDS CROSS OUR REGION. WILL NEED TO MONITOR MODEL TRENDS OF THIS AS WELL. FOR PCPN TYPE ON SUNDAY...HAVE WENT WITH R/S IN THE MORNING TRANSITIONING TO RAIN IN AFTN AS TEMPS LOOK TO RISE ABOVE FREEZING. HEADING INTO SUNDAY NIGHT...THE TROUGH AXIS DEPARTS AND CONDITIONS DRY WITH RISING HEIGHTS BEHIND THE EXITING SYSTEM. MODELS ARE STILL LOOKING DRY MONDAY IN BETWEEN SYSTEMS...AND THEN NEXT WAVE IS PROGGED TO EMERGE ONTO THE PLAINS ON TUESDAY. THERE IS STILL SOME UNCERTAINTY ON DEGREE OF MOISTURE WITH THIS NEXT SYSTEM BUT SMALL CHCS FOR PCPN STILL WARRANTED AS CURRENTLY FORECAST. MILD AIRMASS IN PLACE SHLD MAINTAIN LIQUID CHCS INITIALLY WITH POTENTIAL FOR CHANGE TO SNOW IN COOLER AIR WITH FROPA TUESDAY NIGHT. THE AIRMASS IN GENERAL DURING THE EXTENDED IS NOT OVERLY COLD AND TEMPS LOOK TO BE MORE DEPENDENT ON CLOUDS/PCPN. && .GID WATCHES/WARNINGS/ADVISORIES... NE...NONE. KS...NONE. && $$ UPDATE/SHORT TERM...PFANNKUCH LONG TERM/AVIATION...CF
AREA FORECAST DISCUSSION
NWS BINGHAMTON NY
310 PM EST THU JAN 19 2012 .SYNOPSIS... A COLD FRONT WILL BRING SNOW SQUALLS TO THE REGION TONIGHT AND EARLY FRIDAY MORNING. FRIDAY NIGHT, A STRONGER STORM WILL MOVE THROUGH THE MID ATLANTIC. THIS STORM WILL BRING MODERATE SNOW TO THE SOUTHERN TIER OF NY, CATSKILLS, AND NORTHEASTERN PA. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... EVENT #1 IS VISIBLE ON RADAR, WITH BUF SHOWING ENHANCED RETURNS OVER THE WESTERN EDGE OF LAKE ONTARIO. THIS SHARP COLD FRONT IS WELL DEPICTED BY THE LATEST RUC13 LOW LEVEL LAPSE RATES, AND WE ARE USING THIS MESOSCALE MODEL TO FORECAST A POTENTIAL SQUALL MOVING THROUGH THE FINGER LAKES AND CENTRAL SOUTHERN TIER BY 2-4Z. BASED ON CURRENT RADAR UPSTREAM AND THE STEEP LAPSE RATES, I CAN SEE A QUICK INCH OR TWO FROM THIS SQUALL ALONE BEING POSSIBLE. WE WILL NEED TO CONTINUE TO MONITOR THIS FOR A POTENTIAL SPS TONIGHT. ONCE THE COLD FRONT MOVES THROUGH, WINDS SHIFT OFF THE LAKE OVERNIGHT AND BRING A SOLID 2 TO 4 INCHES OF ADDITIONAL SNOW TO NORTHERN ONEIDA. NOW BELIEVE THE BAND WILL AFFECT EXTREME NORTHERN ONONDAGA, NORTHWESTERN MADISON, AND SOUTHWESTERN ONEIDA WITH 1 TO 3 INCHES OF SNOW. THIS ON TOP OF THE 1 TO 2 INCHES OF SYNOPTIC SNOWFALL JUSTIFIES AN ADVISORY, THOUGH ONLY A SMALL PORTION OF THE NEW ADVISORY COUNTIES WILL BE AFFECTED. A COMBINATION OF SHEAR AND DECREASING LAPSE RATES IN ASSOCIATION WITH FAST APPROACHING ANTICYCLONE WILL KILL OFF THE LAKE MACHINE BY MID MORNING. A FEW LIGHT SNOW SHOWERS MAY PERSIST INTO EARLY AFTERNOON, BUT THE ADVISORY WILL NO LONGER BE NEEDED. && .SHORT TERM /6 PM THIS EVENING THROUGH SUNDAY/... EVENT #2 HAS A STORM SYSTEM SLIDING THROUGH THE MID ATLANTIC REGION FRIDAY NIGHT INTO SATURDAY. GFS REMAINS THE QUICKEST TO MOVE SNOW IN FRIDAY EVENING, WITH THE EURO AND NAM A FEW HOURS SLOWER. HOWEVER THERE IS GOOD AGREEMENT IN STORM TRACK, STRENGTH, AND QPF. THE MODELS WERE COLDER THIS MORNING, BUT THE TREND ALL WINTER HAS BEEN FOR THE MODELS TO BRING THE STORM CENTERS TO THE NORTH IN THE FINAL RUNS, WITH WARM AIR ENCROACHING FROM THE SOUTH. THERE ARE SOME HINTS THAT SOME SLEET COULD MIX IN WITH THE SNOW OVER OUR FAR SOUTHERN FA, BUT RIGHT NOW THE MODEL SOUNDINGS ARE MOST INDICATIVE OF SNOW. THE MODEL QPF LOOKS A LITTLE ON THE HIGH SIDE. HOWEVER EVEN WITH A REDUCTION IN QPF WE ARE VERY CLOSE TO ADVISORY ACCUMS OVER THE SOUTHERN THIRD OF THE FA. THE STORM PULLS OUT QUICKEST ON THE GFS, WITH THE EURO AND NAM AGAIN A FEW HOURS SLOWER. EITHER WAY THE EVENT SHOULD BE DONE BY LATE AFTERNOON SATURDAY, IF NOT SOONER. WINDS SHIFT AROUND TO A NORTHEASTERLY DIRECTION, SO IT DOES NOT APPEAR AS THOUGH OUR FA WILL BE DEALING WITH POST EVENT LAKE SNOWS. && .LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/... HGTS BLD SUN NGT WITH MID AND LL WAA AHD OF A WRN LAKES LOW. LGT PCPN SEEM PSBL WITH MUCH UNCERTAINTY ABT THE TEMP PROFILE. MIXED PCPN SEEMS LIKELY WITH SFC TEMPS NEAR OR BLO FRZG...SO SOME FRZG RAIN PSBL. LOW MVES SLWLY EAST AS AN OCCLUDED FNT RACES EWRD THRU THE OH VLY AND WRN NY. TIMING PUSHES THE FNT THRU THE AREA MON EVE...BUT WITH MODIFIED COLD AIR PUSHING IN FROM THE SW...DO NOT XPCT A DRAMATIC TEMP DROP LATE MON INTO TUE. UPR LOW LIFTS NORTH TUE AS THE TROF AXIS PASSES. AIR IS JUST NOT THAT COLD WITH H8 TEMPS FCSTD IN THE -6C TO -8C RANGE. XPCT SOME MOISTURE WITH THE UPR TROF AND SOME MRGNL LE SNOW SHWRS INTO WED. LATE WED A SFC HI OVER THE OH VLY BLDS IN BUT WITH ZONAL FLOW OVER THE FCST AREA...TEMPS RATHER NEUTRAL AND WITH A WEAK SFC TROF AND APRCHG WC...JUST SOME LGT PCPN IN THE AREA FOR THE END OF THE PD. && .AVIATION /20Z THURSDAY THROUGH TUESDAY/... COLD FNT WILL PASS THRU THE AREA ARND 00Z BRINGING SNOW SHWRS AND MVFR/IFR CONDS. PCPN SHD BE BRIEF INVOF THE FNT...HWVR...CAA BHD THE FNT WILL TRIGGER LE SNOWS AND PROLONGED LWR CONDS AT RME. AS THE FLOW BECOMES MORE NWLY...LE WILL BREAK AWAY FROM THE ALKE AND BRING SOME OCNL MVFR CONDS TO STATIONS IN CNTRL NY THRU THE END OF THE PD. GUSTY SLY WINDS AHD OF THE FNT WILL BECOME WLY AND GUSTY BHD THE FNT EARLY THIS EVE. .OUTLOOK... FRI AFTN...MVFR BECOMING VFR AS LE SNOW WINDS DOWN. SAT...MVFR/IFR IN SNOW. SUN...MAINLY VFR. MON..MVFR POSSIBLE IN RAIN OR SNOW. TUE...MVFR IN SNOW SHWRS && .BGM WATCHES/WARNINGS/ADVISORIES... PA...NONE. NY...WINTER WEATHER ADVISORY UNTIL 11 AM EST FRIDAY FOR NYZ018-036- 037. WINTER WEATHER ADVISORY UNTIL 9 AM EST FRIDAY FOR NYZ009. && $$ SYNOPSIS...DJP NEAR TERM...DJP SHORT TERM...DJP LONG TERM...DGM AVIATION...DGM
AREA FORECAST DISCUSSION
NWS BINGHAMTON NY
254 PM EST THU JAN 19 2012 .SYNOPSIS... A COLD FRONT WILL BRING SNOW SQUALLS TO THE REGION TONIGHT AND EARLY FRIDAY MORNING. FRIDAY NIGHT, A STRONGER STORM WILL MOVE THROUGH THE MID ATLANTIC. THIS STORM WILL BRING MODERATE SNOW TO THE SOUTHERN TIER OF NY, CATSKILLS, AND NORTHEASTERN PA. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... EVENT #1 IS VISIBLE ON RADAR, WITH BUF SHOWING ENHANCED RETURNS OVER THE WESTERN EDGE OF LAKE ONTARIO. THIS SHARP COLD FRONT IS WELL DEPICTED BY THE LATEST RUC13 LOW LEVEL LAPSE RATES, AND WE ARE USING THIS MESOSCALE MODEL TO FORECAST A POTENTIAL SQUALL MOVING THROUGH THE FINGER LAKES AND CENTRAL SOUTHERN TIER BY 2-4Z. BASED ON CURRENT RADAR UPSTREAM AND THE STEEP LAPSE RATES, I CAN SEE A QUICK INCH OR TWO FROM THIS SQUALL ALONE BEING POSSIBLE. WE WILL NEED TO CONTINUE TO MONITOR THIS FOR A POTENTIAL SPS TONIGHT. ONCE THE COLD FRONT MOVES THROUGH, WINDS SHIFT OFF THE LAKE OVERNIGHT AND BRING A SOLID 2 TO 4 INCHES OF ADDITIONAL SNOW TO NORTHERN ONEIDA. NOW BELIEVE THE BAND WILL AFFECT EXTREME NORTHERN ONONDAGA, NORTHWESTERN MADISON, AND SOUTHWESTERN ONEIDA WITH 1 TO 3 INCHES OF SNOW. THIS ON TOP OF THE 1 TO 2 INCHES OF SYNOPTIC SNOWFALL JUSTIFIES AN ADVISORY, THOUGH ONLY A SMALL PORTION OF THE NEW ADVISORY COUNTIES WILL BE AFFECTED. A COMBINATION OF SHEAR AND DECREASING LAPSE RATES IN ASSOCIATION WITH FAST APPROACHING ANTICYCLONE WILL KILL OFF THE LAKE MACHINE BY MID MORNING. A FEW LIGHT SNOW SHOWERS MAY PERSIST INTO EARLY AFTERNOON, BUT THE ADVISORY WILL NO LONGER BE NEEDED. && .SHORT TERM /6 PM THIS EVENING THROUGH SUNDAY/... EVENT #2 HAS A STORM SYSTEM SLIDING THROUGH THE MID ATLANTIC REGION FRIDAY NIGHT INTO SATURDAY. GFS REMAINS THE QUICKEST TO MOVE SNOW IN FRIDAY EVENING, WITH THE EURO AND NAM A FEW HOURS SLOWER. HOWEVER THERE IS GOOD AGREEMENT IN STORM TRACK, STRENGTH, AND QPF. THE MODELS WERE COLDER THIS MORNING, BUT THE TREND ALL WINTER HAS BEEN FOR THE MODELS TO BRING THE STORM CENTERS TO THE NORTH IN THE FINAL RUNS, WITH WARM AIR ENCROACHING FROM THE SOUTH. THERE ARE SOME HINTS THAT SOME SLEET COULD MIX IN WITH THE SNOW OVER OUR FAR SOUTHERN FA, BUT RIGHT NOW THE MODEL SOUNDINGS ARE MOST INDICATIVE OF SNOW. THE MODEL QPF LOOKS A LITTLE ON THE HIGH SIDE. HOWEVER EVEN WITH A REDUCTION IN QPF WE ARE VERY CLOSE TO ADVISORY ACCUMS OVER THE SOUTHERN THIRD OF THE FA. THE STORM PULLS OUT QUICKEST ON THE GFS, WITH THE EURO AND NAM AGAIN A FEW HOURS SLOWER. EITHER WAY THE EVENT SHOULD BE DONE BY LATE AFTERNOON SATURDAY, IF NOT SOONER. WINDS SHIFT AROUND TO A NORTHEASTERLY DIRECTION, SO IT DOES NOT APPEAR AS THOUGH OUR FA WILL BE DEALING WITH POST EVENT LAKE SNOWS. && .LONG TERM /SUNDAY NIGHT THROUGH WEDNESDAY/... PATTERN OF A GENERAL SOUTHWEST FLOW WITH OCCASIONAL WAVES...WILL ALTERNATE US ON EITHER SIDE OF THE 540 DECAMETER LINE IN REGARDS TO 1000-500MB THICKNESS. REGARDLESS OF PRECIPITATION TYPE DURING THE PERIOD...IT WILL BE A WARMER THAN NORMAL PATTERN FOR LATE JANUARY...A THEME THAT HAS DOMINATED MOST OF THIS WINTER SO FAR. WE BEGIN SATURDAY NIGHT THROUGH SUNDAY MORNING...BETWEEN WAVES WITH SEASONABLY COLD LOWS AND MAINLY DRY WEATHER. AN EXTENSION OF A SOUTHERN STREAM UPPER WAVE MAY SKIM US LATE SUNDAY INTO MONDAY MORNING. IF PRECIPITATION MANAGES TO REACH US...GENERAL SET UP AND GFS MODEL SOUNDINGS SUGGEST THERE IS SOME PROSPECT FOR A LIGHT WINTRY MIX INITIALLY BEFORE PLAIN RAIN. GFS/ECWMF AGREE BETTER THOUGH...ON A NORTHERN STREAM TROUGH THEN SWINGING THROUGH LATE MONDAY OR MONDAY NIGHT. THE COLD AIR BEHIND THAT SYSTEM LOOKS PRETTY MEAGER...SO UNLESS BETTER PENETRATION OF COLDER AIR OCCURS...THE RESULTING LAKE RESPONSE ON TUESDAY ALSO LOOKS MEDIOCRE. WE MAY END UP JUST HAVING SCATTERED SNOW SHOWERS SIMPLY FROM SYNOPTIC WRAP AROUND/COMMA HEAD OF SYSTEM...WITH NOT A WHOLE LOT OF ASSISTANCE FROM THE LAKES. THE DOMINANT SOUTHWEST FLOW QUICKLY BRINGS IN WARMER AIR AND SURFACE HIGH PRESSURE INTO WEDNESDAY...AND TEMPERATURES LOOK TO BE ROUGHLY 10 DEGREES ABOVE NORMAL AT THAT TIME. NORTH ATLANTIC OSCILLATION INDEX IS POSITIVE NOW...AND IS FORECAST TO REMAIN POSITIVE THIS WEEK...SUPPORTING THE WARMER THAN NORMAL PATTERN. && .AVIATION /20Z THURSDAY THROUGH TUESDAY/... COLD FNT WILL PASS THRU THE AREA ARND 00Z BRINGING SNOW SHWRS AND MVFR/IFR CONDS. PCPN SHD BE BRIEF INVOF THE FNT...HWVR...CAA BHD THE FNT WILL TRIGGER LE SNOWS AND PROLONGED LWR CONDS AT RME. AS THE FLOW BECOMES MORE NWLY...LE WILL BREAK AWAY FROM THE ALKE AND BRING SOME OCNL MVFR CONDS TO STATIONS IN CNTRL NY THRU THE END OF THE PD. GUSTY SLY WINDS AHD OF THE FNT WILL BECOME WLY AND GUSTY BHD THE FNT EARLY THIS EVE. .OUTLOOK... FRI AFTN...MVFR BECOMING VFR AS LE SNOW WINDS DOWN. SAT...MVFR/IFR IN SNOW. SUN...MAINLY VFR. MON..MVFR POSSIBLE IN RAIN OR SNOW. TUE...MVFR IN SNOW SHWRS && .BGM WATCHES/WARNINGS/ADVISORIES... PA...NONE. NY...WINTER WEATHER ADVISORY FROM 6 PM THIS EVENING TO 11 AM EST FRIDAY FOR NYZ018-036-037. WINTER WEATHER ADVISORY UNTIL 9 AM EST FRIDAY FOR NYZ009. && $$ SYNOPSIS...DJP NEAR TERM...DJP SHORT TERM...DJP LONG TERM...MDP AVIATION...DGM
AREA FORECAST DISCUSSION
NWS BINGHAMTON NY
1240 PM EST THU JAN 19 2012 .SYNOPSIS... MUCH OF TODAY WILL FEATURE DRY WEATHER...AND SEASONABLY CHILLY TEMPERATURES. A COLD FRONT WILL CROSS THE AREA THIS EVENING...ACCOMPANIED BY SNOW SHOWERS...AND A FEW SQUALLS. BEHIND THE FRONT...A BRIEF PERIOD OF LAKE EFFECT SNOW SHOULD IMPACT UPSTATE NEW YORK LATE TONIGHT AND EARLY FRIDAY...BEFORE DIMINISHING IN THE AFTERNOON. A FAST MOVING STORM SYSTEM SHOULD TRACK INTO THE MID-ATLANTIC STATES BY SATURDAY...PERHAPS BRINGING A PERIOD OF SNOW OR MIXED PRECIPITATION TO START THE WEEKEND. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... 930 AM UPDATE...LATEST HRRR REFLECTIVITY SUGGESTS IF THERE IS A SQUALL, IT WILL ARRIVE WELL AFTER SUNSET. WE WILL CONTINUE TO WATCH THE MESOSCALE MODEL TRENDS AND THE OBS/SAT FOR CLUES AS TO TIMING AND INTENSITY OF SNOW SHOWERS. CURRENT GRIDS HAVE BEEN TWEAKED FOR TEMPS. OTHERWISE THE FORECAST LOOKS TO BE IN GOOD SHAPE. 7 AM UPDATE... JUST MINOR TWEAKS TO TEMP/SKY GRIDS. INITIAL BAND OF HIGH-LVL CLDS IS ERODING ATTM...SO WE ADJUSTED TO GO FOR A SUNNIER AM PD...BEFORE THICKER CLDS COME IN FROM THE W TWDS MIDDAY. OTHWS...NO SIG CHANGES. PREV DISC... 5 AM UPDATE...ALL IS QUIET EARLY THIS MRNG...AND SHOULD REMAIN SO FOR MUCH OF THE DAY...WITH JUST AN INCREASE IN MAINLY MID AND HIGH-LVL CLDS FROM MIDDAY ON. TEMPS SHOULD REBOUND INTO THE UPPER 20S OR LOWER 30S FOR MANY LOCALES THIS AFTN...WITH A FAIRLY ROBUST SRLY FLOW DVLPG (HILLTOP SXNS GUSTING TO NEAR 30 MPH AFTER 18Z). A SHARP COLD FRNT WAS CROSSING CNTRL MI AND THE CHICAGO AREA JUST PRIOR TO SUNRISE. THE FRNT WAS MAKING STEADY EWD PROGRESS...AND ALL NEAR-TERM GUIDANCE IS IN AGREEMENT THAT THIS SYSTEM WILL STRETCH ACRS WRN NY BY 21Z. AS MOIST AND FORCING BEGIN TO INCREASE IN ADVANCE OF THIS SYSTEM...SCTD SHSN AND FLRYS SHOULD DEVELOP IN OUR NRN/WRN ZNS BY LATE IN THE DAY...SPCLY THE SRN TUG HILL RGN...WHERE SRLY UPSLOPE FLOW WILL BE WELL ESTABLISHED. && .SHORT TERM /6 PM THIS EVENING THROUGH SATURDAY NIGHT/... 530 AM UPDATE... THE ABV MENTIONED COLD FRNT WILL CROSS THE FA THIS EVE...GENERALLY IN THE 00-04Z TIME FRAME...LIKELY ACCOMPANIED BY A FEW SQUALLS...SPCLY N AND W OF KBGM. ALTHOUGH LOW-LVL LR`S SEEM TO BE A BIT SHORT OF WHAT WE`D NORMALLY SEE IN A FRNTL SQUALL/WINDEX SITN...THEY ARE STILL IN THE 7-8C/KM RANGE IN THE LOWEST 3 KM AGL. THE SUPPORTING UPPER-LVL TROUGH IS ALSO FAIRLY DYNAMIC IN NATURE...AND GOOD LOW-LVL CAA FOLLOWS BEHIND THE SFC FRNT. THUS...WE FEEL SOME AREAS WILL SEE A QUICK INCH OR SO OF ACCUM THIS EVE...MOSTLY CNY. AFTER A 3-5 HOUR PERIOD OF MOSTLY DRY WX...OR PERHAPS A FEW FLRYS/-SHSN... FOR THE LATE EVE/OVERNIGHT TIME FRAME...THE LES MACHINE SHOULD KICK INTO GEAR E AND SE OF LK ONT IN THE PRE-DAWN HRS (06-09Z). NWP AGREEMENT (NAM12/LOCAL WRF/GFS40) IS PRETTY GOOD THAT A SINGLE BAND WILL FIRST IMPACT OSWEGO/LEWIS CNTYS...BEFORE DROPPING INTO NRN ONEIDA BY 08-09Z. FOR A RELATIVELY SHORT PD EARLY FRI...A MULTI-LK INFLUENCE WITH GEO BAY LOOKS PSBL...WHICH WOULD HELP TO ENHANCE MOIST DEPTHS/DZ FAVORABILITY. DUE TO THE COMBO OF 1-3" EARLIER THU EVE WITH THE FRNT...AND THEN AN ADDITIONAL SEVERAL INCHES OF LAKE EFF ACCUM EARLY FRI...A WINTER WX ADVSY HAS BEEN POSTED FOR NRN ONEIDA. PRESENT INDICATIONS ARE THAT THE MAIN LES BAND WILL GRADUALLY WEAKEN AFTER 12Z FRI...AS IT DROPS SWD THROUGH ONONDAGA/MADISON/SRN ONEIDA CNTYS...AND INTO CORTLAND/CHENANGO/OTSEGO CNTYS. A LOWERING INVERSION...COMPROMISED DENDRITE PRODUCTION...AND INCREASED DIR SHEAR...SHOULD ALL TAKE THEIR TOLL...LIKELY CAUSING ACCUMS TO DROP OFF WITH TIME. OUR SRN ZNS SHOULD ONLY SEE A FEW FLRYS AT WORST...WITH PROBABLE BREAKS OF SUNSHINE BY AFTN. AFTER A BRIEF LULL EARLY FRI EVE...THE NEXT SYNOPTIC SYSTEM IS SLATED TO QUICKLY ARRIVE. MODEL EVOLUTION IS ALL PRETTY SIMILAR AT THIS PT...TAKING A FAST MOVING SFC WAVE FROM THE OH/TN VLYS LATE FRI NGT...TO THE DELMARVA RGN ON SAT. ALTHOUGH A STG WAA PATN BECOMES ESTABLISHED THIS PD ACRS NE PA/CNY...ALG WITH A DEEPENING MOIST SUPPLY...THE MAIN UPPER-LVL WAVE IS RATHER FLAT AND FAST MOVG...AND THIS RAPID SYSTEM MOVEMENT COULD WELL KEEP PCPN AMTS DOWN. MY GUT FEELING IS THAT MODEL QPF`S OF 0.3-0.5" LIQUID ARE A BIT OVERDONE...BUT EVEN IF THEY ARE...SEVERAL INCHES OF SNOW ARE STILL PSBL. WE`LL ALSO HAVE TO WATCH FOR THE PSBLTY THAT AN ELEVATED WARM LYR BECOMES INCORPORATED...WHICH COULD POTENTIALLY CREATE A WINTRY MIX SITN FOR PTNS OF THE FA. WE`LL BE MONITORING THIS SYSTEM CLOSELY OVER THE NEXT COUPLE OF DAYS. && .LONG TERM /SUNDAY THROUGH WEDNESDAY/... PATTERN OF A GENERAL SOUTHWEST FLOW WITH OCCASIONAL WAVES...WILL ALTERNATE US ON EITHER SIDE OF THE 540 DECAMETER LINE IN REGARDS TO 1000-500MB THICKNESS. REGARDLESS OF PRECIPITATION TYPE DURING THE PERIOD...IT WILL BE A WARMER THAN NORMAL PATTERN FOR LATE JANUARY...A THEME THAT HAS DOMINATED MOST OF THIS WINTER SO FAR. WE BEGIN SATURDAY NIGHT THROUGH SUNDAY MORNING...BETWEEN WAVES WITH SEASONABLY COLD LOWS AND MAINLY DRY WEATHER. AN EXTENSION OF A SOUTHERN STREAM UPPER WAVE MAY SKIM US LATE SUNDAY INTO MONDAY MORNING. IF PRECIPITATION MANAGES TO REACH US...GENERAL SET UP AND GFS MODEL SOUNDINGS SUGGEST THERE IS SOME PROSPECT FOR A LIGHT WINTRY MIX INITIALLY BEFORE PLAIN RAIN. GFS/ECWMF AGREE BETTER THOUGH...ON A NORTHERN STREAM TROUGH THEN SWINGING THROUGH LATE MONDAY OR MONDAY NIGHT. THE COLD AIR BEHIND THAT SYSTEM LOOKS PRETTY MEAGER...SO UNLESS BETTER PENETRATION OF COLDER AIR OCCURS...THE RESULTING LAKE RESPONSE ON TUESDAY ALSO LOOKS MEDIOCRE. WE MAY END UP JUST HAVING SCATTERED SNOW SHOWERS SIMPLY FROM SYNOPTIC WRAP AROUND/COMMA HEAD OF SYSTEM...WITH NOT A WHOLE LOT OF ASSISTANCE FROM THE LAKES. THE DOMINANT SOUTHWEST FLOW QUICKLY BRINGS IN WARMER AIR AND SURFACE HIGH PRESSURE INTO WEDNESDAY...AND TEMPERATURES LOOK TO BE ROUGHLY 10 DEGREES ABOVE NORMAL AT THAT TIME. NORTH ATLANTIC OSCILLATION INDEX IS POSITIVE NOW...AND IS FORECAST TO REMAIN POSITIVE THIS WEEK...SUPPORTING THE WARMER THAN NORMAL PATTERN. && .AVIATION /18Z THURSDAY THROUGH TUESDAY/... COLD FNT WILL PASS THRU THE AREA ARND 00Z BRINGING SNOW SHWRS AND MVFR/IFR CONDS. PCPN SHD BE BRIEF INVOF THE FNT...HWVR...CAA BHD THE FNT WILL TRIGGER LE SNOWS AND PROLONGED LWR CONDS AT RME. AS THE FLOW BECOMES MORE NWLY...LE WILL BREAK AWAY FROM THE ALKE AND BRING SOME OCNL MVFR CONDS TO STATIONS IN CNTRL NY THRU THE END OF THE PD. GUSTY SLY WINDS AHD OF THE FNT WILL BECOME WLY AND GUSTY BHD THE FNT EARLY THIS EVE. .OUTLOOK... FRI AFTN...MVFR BECOMING VFR AS LE SNOW WINDS DOWN. SAT...MVFR/IFR IN SNOW. SUN...MAINLY VFR. MON..MVFR POSSIBLE IN RAIN OR SNOW. TUE...MVFR IN SNOW SHWRS && .BGM WATCHES/WARNINGS/ADVISORIES... PA...NONE. NY...WINTER WEATHER ADVISORY FROM 5 PM THIS AFTERNOON TO 9 AM EST FRIDAY FOR NYZ009. && $$ SYNOPSIS...MLJ NEAR TERM...DJP/MLJ SHORT TERM...MLJ LONG TERM...MDP AVIATION...DGM
AREA FORECAST DISCUSSION
NWS BINGHAMTON NY
932 AM EST THU JAN 19 2012 .SYNOPSIS... MUCH OF TODAY WILL FEATURE DRY WEATHER...AND SEASONABLY CHILLY TEMPERATURES. A COLD FRONT WILL CROSS THE AREA THIS EVENING...ACCOMPANIED BY SNOW SHOWERS...AND A FEW SQUALLS. BEHIND THE FRONT...A BRIEF PERIOD OF LAKE EFFECT SNOW SHOULD IMPACT UPSTATE NEW YORK LATE TONIGHT AND EARLY FRIDAY...BEFORE DIMINISHING IN THE AFTERNOON. A FAST MOVING STORM SYSTEM SHOULD TRACK INTO THE MID-ATLANTIC STATES BY SATURDAY...PERHAPS BRINGING A PERIOD OF SNOW OR MIXED PRECIPITATION TO START THE WEEKEND. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... 930 AM UPDATE...LATEST HRRR REFLECTIVITY SUGGESTS IF THERE IS A SQUALL, IT WILL ARRIVE WELL AFTER SUNSET. WE WILL CONTINUE TO WATCH THE MESOSCALE MODEL TRENDS AND THE OBS/SAT FOR CLUES AS TO TIMING AND INTENSITY OF SNOW SHOWERS. CURRENT GRIDS HAVE BEEN TWEAKED FOR TEMPS. OTHERWISE THE FORECAST LOOKS TO BE IN GOOD SHAPE. 7 AM UPDATE... JUST MINOR TWEAKS TO TEMP/SKY GRIDS. INITIAL BAND OF HIGH-LVL CLDS IS ERODING ATTM...SO WE ADJUSTED TO GO FOR A SUNNIER AM PD...BEFORE THICKER CLDS COME IN FROM THE W TWDS MIDDAY. OTHWS...NO SIG CHANGES. PREV DISC... 5 AM UPDATE...ALL IS QUIET EARLY THIS MRNG...AND SHOULD REMAIN SO FOR MUCH OF THE DAY...WITH JUST AN INCREASE IN MAINLY MID AND HIGH-LVL CLDS FROM MIDDAY ON. TEMPS SHOULD REBOUND INTO THE UPPER 20S OR LOWER 30S FOR MANY LOCALES THIS AFTN...WITH A FAIRLY ROBUST SRLY FLOW DVLPG (HILLTOP SXNS GUSTING TO NEAR 30 MPH AFTER 18Z). A SHARP COLD FRNT WAS CROSSING CNTRL MI AND THE CHICAGO AREA JUST PRIOR TO SUNRISE. THE FRNT WAS MAKING STEADY EWD PROGRESS...AND ALL NEAR-TERM GUIDANCE IS IN AGREEMENT THAT THIS SYSTEM WILL STRETCH ACRS WRN NY BY 21Z. AS MOIST AND FORCING BEGIN TO INCREASE IN ADVANCE OF THIS SYSTEM...SCTD SHSN AND FLRYS SHOULD DEVELOP IN OUR NRN/WRN ZNS BY LATE IN THE DAY...SPCLY THE SRN TUG HILL RGN...WHERE SRLY UPSLOPE FLOW WILL BE WELL ESTABLISHED. && .SHORT TERM /6 PM THIS EVENING THROUGH SATURDAY NIGHT/... 530 AM UPDATE... THE ABV MENTIONED COLD FRNT WILL CROSS THE FA THIS EVE...GENERALLY IN THE 00-04Z TIME FRAME...LIKELY ACCOMPANIED BY A FEW SQUALLS...SPCLY N AND W OF KBGM. ALTHOUGH LOW-LVL LR`S SEEM TO BE A BIT SHORT OF WHAT WE`D NORMALLY SEE IN A FRNTL SQUALL/WINDEX SITN...THEY ARE STILL IN THE 7-8C/KM RANGE IN THE LOWEST 3 KM AGL. THE SUPPORTING UPPER-LVL TROUGH IS ALSO FAIRLY DYNAMIC IN NATURE...AND GOOD LOW-LVL CAA FOLLOWS BEHIND THE SFC FRNT. THUS...WE FEEL SOME AREAS WILL SEE A QUICK INCH OR SO OF ACCUM THIS EVE...MOSTLY CNY. AFTER A 3-5 HOUR PERIOD OF MOSTLY DRY WX...OR PERHAPS A FEW FLRYS/-SHSN... FOR THE LATE EVE/OVERNIGHT TIME FRAME...THE LES MACHINE SHOULD KICK INTO GEAR E AND SE OF LK ONT IN THE PRE-DAWN HRS (06-09Z). NWP AGREEMENT (NAM12/LOCAL WRF/GFS40) IS PRETTY GOOD THAT A SINGLE BAND WILL FIRST IMPACT OSWEGO/LEWIS CNTYS...BEFORE DROPPING INTO NRN ONEIDA BY 08-09Z. FOR A RELATIVELY SHORT PD EARLY FRI...A MULTI-LK INFLUENCE WITH GEO BAY LOOKS PSBL...WHICH WOULD HELP TO ENHANCE MOIST DEPTHS/DZ FAVORABILITY. DUE TO THE COMBO OF 1-3" EARLIER THU EVE WITH THE FRNT...AND THEN AN ADDITIONAL SEVERAL INCHES OF LAKE EFF ACCUM EARLY FRI...A WINTER WX ADVSY HAS BEEN POSTED FOR NRN ONEIDA. PRESENT INDICATIONS ARE THAT THE MAIN LES BAND WILL GRADUALLY WEAKEN AFTER 12Z FRI...AS IT DROPS SWD THROUGH ONONDAGA/MADISON/SRN ONEIDA CNTYS...AND INTO CORTLAND/CHENANGO/OTSEGO CNTYS. A LOWERING INVERSION...COMPROMISED DENDRITE PRODUCTION...AND INCREASED DIR SHEAR...SHOULD ALL TAKE THEIR TOLL...LIKELY CAUSING ACCUMS TO DROP OFF WITH TIME. OUR SRN ZNS SHOULD ONLY SEE A FEW FLRYS AT WORST...WITH PROBABLE BREAKS OF SUNSHINE BY AFTN. AFTER A BRIEF LULL EARLY FRI EVE...THE NEXT SYNOPTIC SYSTEM IS SLATED TO QUICKLY ARRIVE. MODEL EVOLUTION IS ALL PRETTY SIMILAR AT THIS PT...TAKING A FAST MOVING SFC WAVE FROM THE OH/TN VLYS LATE FRI NGT...TO THE DELMARVA RGN ON SAT. ALTHOUGH A STG WAA PATN BECOMES ESTABLISHED THIS PD ACRS NE PA/CNY...ALG WITH A DEEPENING MOIST SUPPLY...THE MAIN UPPER-LVL WAVE IS RATHER FLAT AND FAST MOVG...AND THIS RAPID SYSTEM MOVEMENT COULD WELL KEEP PCPN AMTS DOWN. MY GUT FEELING IS THAT MODEL QPF`S OF 0.3-0.5" LIQUID ARE A BIT OVERDONE...BUT EVEN IF THEY ARE...SEVERAL INCHES OF SNOW ARE STILL PSBL. WE`LL ALSO HAVE TO WATCH FOR THE PSBLTY THAT AN ELEVATED WARM LYR BECOMES INCORPORATED...WHICH COULD POTENTIALLY CREATE A WINTRY MIX SITN FOR PTNS OF THE FA. WE`LL BE MONITORING THIS SYSTEM CLOSELY OVER THE NEXT COUPLE OF DAYS. && .LONG TERM /SUNDAY THROUGH WEDNESDAY/... PATTERN OF A GENERAL SOUTHWEST FLOW WITH OCCASIONAL WAVES...WILL ALTERNATE US ON EITHER SIDE OF THE 540 DECAMETER LINE IN REGARDS TO 1000-500MB THICKNESS. REGARDLESS OF PRECIPITATION TYPE DURING THE PERIOD...IT WILL BE A WARMER THAN NORMAL PATTERN FOR LATE JANUARY...A THEME THAT HAS DOMINATED MOST OF THIS WINTER SO FAR. WE BEGIN SATURDAY NIGHT THROUGH SUNDAY MORNING...BETWEEN WAVES WITH SEASONABLY COLD LOWS AND MAINLY DRY WEATHER. AN EXTENSION OF A SOUTHERN STREAM UPPER WAVE MAY SKIM US LATE SUNDAY INTO MONDAY MORNING. IF PRECIPITATION MANAGES TO REACH US...GENERAL SET UP AND GFS MODEL SOUNDINGS SUGGEST THERE IS SOME PROSPECT FOR A LIGHT WINTRY MIX INITIALLY BEFORE PLAIN RAIN. GFS/ECWMF AGREE BETTER THOUGH...ON A NORTHERN STREAM TROUGH THEN SWINGING THROUGH LATE MONDAY OR MONDAY NIGHT. THE COLD AIR BEHIND THAT SYSTEM LOOKS PRETTY MEAGER...SO UNLESS BETTER PENETRATION OF COLDER AIR OCCURS...THE RESULTING LAKE RESPONSE ON TUESDAY ALSO LOOKS MEDIOCRE. WE MAY END UP JUST HAVING SCATTERED SNOW SHOWERS SIMPLY FROM SYNOPTIC WRAP AROUND/COMMA HEAD OF SYSTEM...WITH NOT A WHOLE LOT OF ASSISTANCE FROM THE LAKES. THE DOMINANT SOUTHWEST FLOW QUICKLY BRINGS IN WARMER AIR AND SURFACE HIGH PRESSURE INTO WEDNESDAY...AND TEMPERATURES LOOK TO BE ROUGHLY 10 DEGREES ABOVE NORMAL AT THAT TIME. NORTH ATLANTIC OSCILLATION INDEX IS POSITIVE NOW...AND IS FORECAST TO REMAIN POSITIVE THIS WEEK...SUPPORTING THE WARMER THAN NORMAL PATTERN. && .AVIATION /15Z THURSDAY THROUGH MONDAY/... HIGH PRESSURE WILL WEAKEN TODAY AS A LOW PRESSURE SYSTEM APPROACHES THE REGION FROM THE WEST. HIGH CLOUDS WILL MOVE IN LATER THIS MORNING. VFR CONDITIONS WILL LAST UNDER A HIGH TO MID DECK OF CLOUDS UNTIL THE VERY LATE AFTERNOON OR EARLY EVENING. THEN CIGS WILL DROP TO MVFR AND LIGHT SNOW SHOWERS WILL BEGIN TO MOVE IN. A COLD FRONT WILL THEN CROSS THE AREA TONIGHT, AROUND MIDNIGHT. A AREA OF HEAVIER SNOW IS EXPECTED ALONG WITH THE FRONT, WHICH MAY BRING A PERIOD OF IFR CIGS AND VSBYS TO MOST TAF SITES, ESPECIALLY FURTHER NORTH, SUCH AS SYR AND RME. CONDITIONS SHOULD BEGIN TO IMPROVE IN THE PREDAWN HOURS TOMORROW MORNING BEHIND THE FRONT, WITH THE EXCEPTION OF RME AND SYR, WHERE LAKE EFFECT SNOW IS EXPECTED TO DEVELOP ONCE AGAIN. WINDS WILL PICK UP OUT OF THE SOUTH THIS MORNING BETWEEN 5 AND 10 KTS. AS THE PRESSURE GRADIENT INCREASES, WITH THE LOW APPROACHING, WINDS WILL INCREASE TO AROUND 15KTS WITH GUSTS TO AROUND 25 KTS. THE GUSTS WILL LAST UNTIL THE FRONTAL PASSAGE AND WILL AFFECT VSBYS WITH BLSN. BEHIND THE FRONT, WINDS WILL TURN WNW BETWEEN 5 AND 10 KTS. .OUTLOOK... LATE THURSDAY TO FRIDAY...MVFR. LIGHT SNOW CHANGING TO LAKE EFFECT SNOW IN NY BY FRIDAY. SATURDAY...MVFR IN SNOW SHOWERS. SUNDAY...MAINLY VFR. MONDAY..MVFR POSSIBLE IN RAIN OR SNOW. && .BGM WATCHES/WARNINGS/ADVISORIES... PA...NONE. NY...WINTER WEATHER ADVISORY FROM 5 PM THIS AFTERNOON TO 9 AM EST FRIDAY FOR NYZ009. && $$ SYNOPSIS...MLJ NEAR TERM...DJP/MLJ SHORT TERM...MLJ LONG TERM...MDP AVIATION...SLI
AREA FORECAST DISCUSSION
NWS RALEIGH NC
925 PM EST FRI JAN 20 2012 .SYNOPSIS... AN AREA OF LOW PRESSURE AND ITS ASSOCIATED FRONTAL SYSTEM WILL BRING UNSETTLED WEATHER TO THE CAROLINAS AND SOUTHERN VIRGINIA THROUGH SATURDAY NIGHT. AN AREA OF HIGH PRESSURE WILL BUILD SOUTH INTO OUR REGION SUNDAY...BRINGING DAMP AND CHILLY CONDITIONS. A COLD FRONT WILL CROSS THE AREA ON MONDAY. && .NEAR TERM /THROUGH SATURDAY/... AS OF 925 PM FRIDAY... LIGHT RAIN AND A WEDGE LIKE AIRMASS HAVE DEVELOPED FROM CENTRAL NC TO NORTHERN GA THIS EVENING...WHILE A WARM FRONT IS STARTING TO LIFT THROUGH AL AS A WEAK LOW PRESSURE DEVELOPS OVER AR. THE LIGHT RAIN...SUPPORTED BY ISENTROPIC LIFT ALONG AND NORTH OF THE WEDGE FRONT/WEAK 850MB WARM FRONT AND DIFFLUENT FLOW IN THE EXIT OF A WEAK 300MB JET AXIS STRETCHED ACROSS THE LOWER MS VALLEY...CONTINUES TO BLOSSOM TO OUR SOUTHWEST AND SPREAD ACROSS CENTRAL NC. THE ONGOING RAINFALL IS LIGHT AND RAINFALL TOTALS HAVE BEEN BELOW A TENTH OF AN INCH. RUC ISENTROPIC LIFT FORECASTS SHOW STRONG LIFT CONTINUING IN THE 290-300K LAYER THROUGH 09Z BEFORE SOME DRIER AIR ALOFT..NOTED AT 700MB...ADVECTS IN FROM THE SOUTHWEST AHEAD OF THE TROUGH AXIS TO APPROACH LATER IN THE DAY SATURDAY. THUS..RAIN IS LIKELY TO TURN TO DRIZZLE FROM WEST TO EAST AFTER 09Z..BUT CATEGORICAL POPS SEEM NECESSARY EVERYWHERE FOR THE BALANCE OF THE NIGHT. WITH A 5K FT WEDGE AIRMASS (PER 00Z KGSO RAOB) LOCKING IN...THE CURRENT FORECAST OF TEMPS IN THE LOW TO MID 40S WILL REMAINING NEARLY STEADY OR RISING SLIGHTLY LOOKS GOOD. -SMITH THE WARM ADVECTION DRIVEN PRECIP SHOULD COME TO AN END FROM WEST TO EAST BY EARLY SATURDAY MORNING. HOWEVER...THE LULL IN PRECIP WILL BE SHORT LIVED AS A COLD FRONT ADVANCES TOWARDS THE AREA DURING THE DAY ON SATURDAY. SOUTHWESTERLY FLOW AHEAD OF THE FRONT WILL PUMP WARM AND MOIST AIR INTO THE REGION...WITH MAX TEMPS EXPECTED TO RISE INTO THE 60S AREAWIDE (MAYBE EVEN PUSHING 70 DEGREES ACROSS THE SOUTHEAST). ALTHOUGH SOME DIURNAL DESTABILIZATION IS EXPECTED TO OCCUR ACROSS THE EASTERN HALF OF THE FORECAST AREA...DEWPOINTS ARE ONLY EXPECTED TO REACH INTO THE LOW TO MID 50S...THUS LIMITING THE AMOUNT OF INSTABILITY. NAM FORECAST SOUNDINGS SHOW AT BEST CAPE VALUES OF LESS THAN 500 J/KG...WHILE THE GFS FORECAST SOUNDINGS SHOW NO INSTABILITY AT ALL. NEVERTHELESS...DECENT SHEAR WILL BE IN PLACE OVER THE REGION AND IF WE ARE ABLE TO REALIZE SOME OF THE INSTABILITY THE NAM INDICATES...AN ISOLATED THUNDERSTORM OR TWO CANNOT BE RULED OUT SATURDAY AFTERNOON. HOWEVER...FOR NOW WILL LEAVE ANY MENTION OF THUNDER OUT OF THE FORECAST DUE TO THE UNCERTAINTY. OVERALL...AFTER THE BRIEF LULL IN PRECIP SATURDAY MORNING...AM EXPECTING A LINE OF SHOWERS TO PROGRESS FROM NORTHWEST TO SOUTHEAST SATURDAY AFTERNOON/EVENING. && .SHORT TERM /SATURDAY NIGHT THROUGH SUNDAY NIGHT/... AS OF 250 PM FRIDAY... ON SATURDAY EVENING...SHOWERS WILL BE ONGOING AS THE UPPER TROUGH AND ASSOCIATED COLD FRONT PUSHES ACROSS THE REGION. THE EC AND NAM HAVE TRENDED FASTER WITH DROPPING THE SFC COLD FRONT SOUTH THROUGH THE AREA SHORTLY AFTER MIDNIGHT SATURDAY NIGHT WITH SHOWERS TRANSITIONING TO RAIN AND THEN DRIZZLE FROM NW TO SE ACROSS CENTRAL NC AS WE LOSS MID AND UPPER LEVEL SATURATION AS DRYING AND SUBSIDENCE ALOFT SPREAD INTO THE AREA BEHIND THE EXITING SHORTWAVE TROUGH. A STRENGTHENING +1030MB SURFACE COLD AIR HIGH OVER NEW ENGLAND WILL ADVECT COLDER AND DRIER AIR INTO CENTRAL NC DURING THE PREDAWN HOURS...AND THIS WILL SET THE STAGE FOR A SHORT-LIVED HYBRID DAMMING EVENT ON SUNDAY AS CONTINUED SWLY FLOW ALOFT WILL SUPPORT WEAK OVERRUNNING ACROSS CENTRAL NC AS THE NEXT PACIFIC TROUGH PUSHES EAST INTO THE CENTRAL US. WITH MOIST COLUMN NOT EXTENDING MUCH BEYOND 700MB...LITTLE TO NO ADDITIONAL ACCUMULATIONS ARE EXPECTED WITH PERIODS OF DRIZZLE THROUGHOUT THE DAY...WITH THE POTENTIAL THAT THE NORTHWEST PIEDMONT COULD SEE A BRIEF PERIOD OF FREEZING DRIZZLE EARLY SUNDAY MORNING AS MODEL SOUNDINGS DRIVE SFC TEMPERATURES SUNDAY MORNING INTO THE LOWER TO MID 30S WITH WET BULB-FREEZING LINE DEPICTED IN THE SAME CLIMATOLOGICALLY FAVORED AREA AS WELL. FURTHERMORE A HANDFUL OF SREF MEMBERS ALSO INDICATE A BRIEF CHANGEOVER OF FREEZING DRIZZLE WITH LITTLE TO NO ACCUMULATION( A COUPLE OF HUNDREDTHS OR LESS). SFC WET-BULBS ARE EXPECTED TO REBOUND INTO THE MID 30S THROUGH THE MORNING WITH MINIMAL RECOVERY THROUGHOUT THE DAY. AFTER MORNING LOWS IN THE MID TO UPPER 30S NORTH TO MID 40S SOUTH...EXPECT A NET INCREASE OF ONLY 3 TO 5 DEGREES ACROSS THE AREA. STALLED FRONTAL ZONE SOUTH OF THE AREA BEGINS TO RETREAT NORTHWARD AS A WARM FRONT SUNDAY NIGHT...WITH THE SOUTHERN RETURN FLOW OVERTAKING THE SHALLOW CAD AIRMASS ALONG THE SOUTHERN AND EASTERN FLANKS...WHILE REMAINING LOCKED IN OVER THE NW PIEDMONT REGION. THIS WILL FAVOR NEAR STEADY TEMPERATURES OVERNIGHT ACROSS THE NW WITH TEMPERATES SLIGHTLY RISING ACROSS THE SANDHILLS AND COASTAL COUNTIES. && .LONG TERM /MONDAY THROUGH FRIDAY/... AS OF 250 PM FRIDAY... MONDAY AND MONDAY NIGHT: LINGERING WEDGE REGIME SHOULD UNDERGO A RELATIVELY QUICK DEMISE OWING TO SURFACE DIVERGENCE AS PROGRESSIVE SURFACE HIGH OVER NEW ENGLAND PULLS OUT TO SEA...AND STRONG SHEAR-INDUCED MIXING VIA STRENGTHENING SWLY FLOW OF 35 TO 40KTS AS THE UPPER TROUGH AND ASSOCIATED COLD FRONT APPROACH FROM THE WEST. TEMPERATURES BREAK OUT IN THE LOWER TO UPPER 60S ON MONDAY AFTERNOON WITH BREEZY SWLY WINDS WITH A LULL IN PRECIP MONDAY MORNING...BEFORE RAIN CHANCES RAMP BACK UP BY THE AFTERNOON WITH THE TRAILING SURFACE COLD FRONT MOVING THROUGH THE AREA BETWEEN MONDAY 18Z TO 06Z. INSTABILITY IS EXPECTED TO BE LIMITED BY WIDESPREAD CLOUDS...ESPECIALLY IF THE FASTER GFS VERIFIES...BUT GIVEN STRONG DEEP LAYER SHEAR...SOME STRONG STORMS ARE POSSIBLE. TOO EARLY TO INCLUDE A MENTION OF THUNDER AT THIS TIME...BUT WILL CONTINUE TO MONITOR. TEMPERATURES WILL REMAIN ABOVE NORMAL WITH DRY CONDITIONS TUESDAY THROUGH WEDNESDAY AS AS WE WAIT FOR THE NEXT PACIFIC SHORTWAVE TROUGH TO TAKE A MORE SOUTHERN ROUTE THROUGH THE SOUTHERN US. NWP MODEL GUIDANCE DIVERGE BY THURSDAY...WITH HIGH UNCERTAINTY REGARDING WHETHER TO PHASE THE SOUTHERN STREAM STORM SYSTEM WITH NORTHERN STREAM ENERGY AND EVOLVE IT INTO AN OPEN WAVE OR TO KEEP THE SOUTHERN STORM SYSTEM CUT-OFF FROM THE MAIN BELT OF WESTERLIES...WHILE HOLDING IT BACK ACROSS THE TEXAS/SOUTHERN PLAINS. GIVEN LOW CONFIDENCE...WILL REMAIN CONSERVATIVE WITH POPS...WITH SLIGHT TO SMALL CHANCE POPS FROM WEDNESDAY NIGHT ON. && .AVIATION /00Z SATURDAY THROUGH WEDNESDAY/... AS OF 713 PM FRIDAY... CONDITIONS WILL GRADUALLY DETERIORATE TO MVFR/IFR CONDITIONS THROUGH 2 AM AS AREAS OF LIGHT RAIN SLOWLY SATURATE THE LOWER LAYERS OF THE ATMOSPHERE. WIDESPREAD LIGHT RAIN WILL PERSIST ACROSS CENTRAL NC THROUGH 3 AM...AFTERWHICH THE RAIN WILL GRADUALLY DIMINISH TO SPOTTY DRIZZLE AND SOME FOG. BY 9-11 AM SATURDAY...CEILINGS MAY TEMPORARILY LIFT INTO THE LOW END VFR CATEGORY AS SURFACE WINDS WILL BECOME SLY AND INCREASE TO 10-15KTS WITH GUSTS 20-25 KTS. AN AREA OF SHOWERS SHOULD OVERSPREAD CENTRAL NC LATE SATURDAY AND SATURDAY NIGHT AS A COLD FRONT CROSSES THE REGION. BEHIND THE FRONT...THE SHOWERS WILL END THOUGH CEILINGS WILL BE IN THE 800-2000FT RANGE SUNDAY INTO SUNDAY NIGHT. AREAS OF FOG MAY BE PROBABLE BY SUNDAY NIGHT AS SLY WINDS JUST ABOVE THE SURFACE ADVECT WARMER AIR OVER THE COOLER STABLE AIR NEAR THE SURFACE. MONDAY...CEILINGS EXPECTED TO REMAIN IFR/MVFR AS ANOTHER COLD FRONT CROSSES THE REGION WITH SHOWERS OCCURRING AHEAD OF THE FRONT. THE SHOWERS ARE MOST LIKELY TO OCCUR MONDAY AFTERNOON. THE FRONT WILL EXIT THE REGION MONDAY NIGHT. NW FLOW BEHIND THE FRONT WILL USHER DRIER MORE STABLE AIR INTO THE REGION...ENDING THE SHOWERS AND DISSIPATING CLOUD COVERAGE. VFR CONDITIONS CURRENTLY ANTICIPATED FOR TUESDAY AND WEDNESDAY. && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...WSS NEAR TERM...KRR/SMITH SHORT TERM...CBL LONG TERM...CBL AVIATION...WSS
AREA FORECAST DISCUSSION
NWS CLEVELAND OH
706 PM EST FRI JAN 20 2012 .SYNOPSIS... AN AREA OF LOW PRESSURE WILL MOVE UP THE OHIO VALLEY TONIGHT AND REACH THE CAROLINAS SATURDAY. HIGH PRESSURE WILL RETURN FOR THE SECOND HALF OF THE WEEKEND. A FRONT WILL MOVE ACROSS THE REGION MONDAY. && .NEAR TERM /UNTIL 6 AM SATURDAY MORNING/... ONLY MADE A FEW TWEAKS TO HOURLY TEMPS THE NEXT COUPLE OF HOURS. OTHERWISE ALL REMAINS ON TRACK WITH A SOLID ADVISORY CRITERIA SNOWFALL. THE SNOW WILL CONTINUE TO SPREAD EAST RAPIDLY THIS EVENING. THE RUC MODEL IS A LITTLE SLOW IN SPREADING THE SNOW...THIS MAY BE TOO SLOW. THE LOW LEVELS ARE DRY...SO AS SOON AS IT MOISTENS UP THE VISIBILITY IN SNOW WILL DROP QUICKLY. ON THE EDGE ABOUT WHETHER ANY AREAS NEED TO BE UPGRADED TO A WARNING. AT THIS TIME GOING MORE WITH THE GFS/SREF/ECMWF TRACK OF THE LOW... WHICH WILL KEEP IT MAINLY SNOW AND SHOULD HAVE THE HEAVIEST AMOUNTS SOUTH OF THE FORECAST AREA. WILL ADD A CHANCE OF SLEET AND FREEZING RAIN TO A FEW OF THE SOUTHERN COUNTIES AS THE 850 MB TEMPERATURE WARMS. THE AREAS THAT COULD GET OVER 6 INCHES COULD BE THE LAKESHORE AREAS AS THE FLOW BECOMES NORTHEAST FOR A FEW HOURS LATE TONIGHT AND WE GET SOME ENHANCEMENT. THE OTHER AREAS WOULD BE A WEST TO EAST BAND OF HEAVY SNOW FROM FDY TO MFD TO THE YOUNGSTOWN AREA. THE OMEGA AND SNOW GROWTH IS NOT THAT IMPRESSIVE. THE SNOW COULD BE A LITTLE FLUFFY FOR A WHILE WITH THE COLD TEMPERATURES AT FIRST. AFTER CAREFUL CONSIDERATION WILL NOT UPGRADE. WILL DEFINITELY HAVE SOME GRIDS WITH A THREAT OF HEAVY SNOW IN THEM. TEMPERATURES WILL RISE SOME AND THEN HOLD STEADY. && .SHORT TERM /6 AM SATURDAY MORNING THROUGH MONDAY NIGHT/... SOME LEFT OVER SNOW IN THE AM...MAINLY EARLY. THE AIRMASS DRIES OUT QUICKLY SATURDAY AM. THE BUFKIT NAM IS TRYING TO INDICATE SOME FREEZING DRIZZLE SATURDAY MORNING...AT THIS TIME WILL NOT FORECAST IT AS THE AIRMASS SHOULD DRY OUT RAPIDLY AND THE CLOUDS DECREASE. ON THE EDGE ABOUT THE LOWS SATURDAY NIGHT WITH MOSTLY CLEAR SKIES...SOME CIRRUS...A LITTLE WIND AND WARMING ALOFT. IF HIGH PRESSURE WAS OVER THE AREA IT WOULD BE VERY COLD BECAUSE OF THE SNOW COVER. DID GO ON THE COLDER SIDE OF THE GFS MOS. INCREASING CLOUDS IN THE WARM ADVECTION SUNDAY. A THREAT OF SHOWERS IN THE WEST BY LATE AFTERNOON. OTHERWISE AN INCREASING THREAT OF SHOWERS SUNDAY NIGHT AND THEN AS THE COLDER AIR COMES IN MONDAY THE RAIN SHOWERS WILL CHANGE TO SNOW SHOWERS. NO THUNDER ATTM BUT THIS WILL HAVE TO BE WATCHED. THE ONLY TIMING WAS TO MENTION THAT IT WOULD BE IN THE AFTERNOON...IT COULD BE LATE AFTERNOON OVER THE EASTERN COUNTIES. SOME LAKE ENHANCED SNOW SHOWERS MAY OCCUR MONDAY NIGHT IN THE SNOW BELT...THE LAKE AND 850 MB TEMPERATURE DIFFERENCE WILL BE NEAR 12C. && .LONG TERM /TUESDAY THROUGH FRIDAY/... THERE MAY BE SOME LINGERING SNOW SHOWERS INTO EARLY TUESDAY AFTERNOON. HIGH PRESSURE WILL THEN GAIN CONTROL OF THE REGION TUESDAY NIGHT AND CONTINUE INTO WEDNESDAY. THE NEXT STORM SYSTEM LOOKS LIKE IT WILL APPROACH FROM THE SOUTHERN PLAINS WEDNESDAY NIGHT INTO THURSDAY AS A CLIPPER TYPE SYSTEM MOVES THROUGH THE NORTHERN JET STREAM. THIS WILL BE A SIMILAR EVENT TO WHAT IS OCCURRING TONIGHT BUT THE REGION WILL BE SLIGHTLY WARMER. THIS MAY END UP PRODUCING A WINTRY MIX BEFORE CHANGING OVER TO RAIN. MODELS DIFFER ON THE THE TIMING WITH THIS STORM SYSTEM SO ONLY WENT WITH CHANCE POPS AT THIS TIME. AFTER HIGHS IN THE MIDDLE 30S ON TUESDAY IT APPEARS THAT HIGHS WILL WARM TO AROUND 40 WEDNESDAY INTO THURSDAY. && .AVIATION /00Z SATURDAY THROUGH WEDNESDAY/... THE SNOW AND IFR CONDITIONS WILL MOVE QUICKLY EAST EARLY TONIGHT REACHING NORTHWEST PENNSYLVANIA BY 03Z OR SO. THE SNOW WILL BE MODERATE TO HEAVY FOR 4-5 HOURS WITH LIFR CONDITIONS POSSIBLE DURING THIS TIME. THE SNOW WILL END FROM WEST TO EAST SATURDAY MORNING 08Z-13Z. VISIBILITIES WILL IMPROVE TO VFR WHEN THE SNOW STOPS BUT MVFR CEILINGS WILL LINGER FOR A WHILE. VFR CEILINGS (035BKN) WILL DEVELOP SATURDAY AFTERNOON WITH CLEARING SOON AFTER. VFR AND CLEAR SAILING SATURDAY NIGHT. .OUTLOOK...NON VFR CONDITIONS WILL REDEVELOP MONDAY IN RAIN SHOWERS...RAIN WILL TURN TO SNOW MONDAY NIGHT...SNOW WILL LINGER INTO TUESDAY ACROSS NE OH/NW PA. && .MARINE... NORTHEAST WINDS OF 10-20 KNOTS WILL DEVELOP OVERNIGHT AS LOW PRESSURE TRACKS THROUGH THE LOWER OHIO VALLEY. WAVES IN THE NEARSHORE WATERS WILL BUILD NEAR THE ISLANDS...POSSIBLY APPROACHING 4 FEET FOR A BRIEF WINDOW SATURDAY MORNING. AT THIS TIME IT LOOKS TOO MARGINAL...ESPECIALLY WITH SOME ICE DEVELOPING ALONG THE SHORELINE FOR A SMALL CRAFT ADVISORY. WE WILL TAKE ANOTHER LOOK AT HOW WINDS DO OVERNIGHT BEFORE MAKING THE FINAL CALL. THIS SYSTEM WILL QUICKLY PASS TO THE EAST ON SATURDAY AS HIGH PRESSURE BUILDS OVER THE CENTRAL GREAT LAKES. THE NEXT LOW PRESSURE SYSTEM TO WATCH WILL EVOLVE OUT OF THE PLAINS AND APPROACH THE WESTERN AND UPPER GREAT LAKES ON MONDAY. THIS WILL RESULT IN INCREASING SOUTHERLY WINDS...VEERING TO SOUTHWEST BEHIND A COLD FRONT LATE IN THE DAY. SMALL CRAFT ADVISORIES MAY BE NEEDED EARLY NEXT WEEK. && .CLE WATCHES/WARNINGS/ADVISORIES... OH...WINTER WEATHER ADVISORY UNTIL 9 AM EST SATURDAY FOR OHZ010>014- 020>023-029>033-037-038-047-089. WINTER WEATHER ADVISORY UNTIL 6 AM EST SATURDAY FOR OHZ003- 006>009-017>019-027-028-036. PA...WINTER WEATHER ADVISORY UNTIL 9 AM EST SATURDAY FOR PAZ001>003. MARINE...NONE. && $$ SYNOPSIS...KIELTYKA NEAR TERM...KIELTYKA/OUDEMAN SHORT TERM...KIELTYKA LONG TERM...MULLEN AVIATION...KOSARIK MARINE...KEC
AREA FORECAST DISCUSSION...UPDATED
NWS AMARILLO TX
1113 PM CST WED JAN 18 2012 .AVIATION... LOW CONFIDENCE ON WIND GUSTS REACHING 40 KNOTS OR HIGHER AT THE AMARILLO TAF SITE TONIGHT. IT APPEARS THAT THE STRONGEST WINDS WILL REMAIN WEST OF THE AMARILLO TAF SITE. THEREFORE...WILL CARRY WESTERLY WINDS 15 TO 25 OR 30 KNOTS WITH HIGHER GUSTS BRIEFLY UNTIL AROUND 08Z TO 10Z THURSDAY AT AMARILLO. OTHERWISE...SOUTHWESTERLY TO WESTERLY WINDS 10 TO 20 KNOTS TONIGHT. WEAK BACKDOOR COLD FRONT WILL AFFECT THE GUYMON TAF SITE THURSDAY CAUSING THE WINDS TO BECOME SOUTHEASTERLY TO NORTHEASTERLY 5 TO 15 KNOTS AFTER 15Z THURSDAY. AT THE DALHART AND AMARILLO TAF SITES...WINDS WILL BECOME MORE SOUTHERLY OR SOUTHWESTERLY 5 TO 15 KNOTS AFTER 16Z TO 20Z THURSDAY. CONSIDERABLE HIGH LEVEL CLOUDINESS WILL ALLOW VFR CONDITIONS TO PREVAIL. SCHNEIDER && .PREV DISCUSSION... /ISSUED 1005 PM CST WED JAN 18 2012/ UPDATE... MAIN CHANGE WAS TO LOWER WIND SPEEDS TONIGHT...MAINLY ACROSS THE WESTERN AND SOUTHWESTERN TEXAS PANHANDLE. DISCUSSION... STILL A LOW CONFIDENCE FORECAST WITH RESPECT TO WIND SPEEDS OVERNIGHT. TUCUMCARI WIND PROFILER DATA INDICATES 0-1 KM FLOW HAS INCREASED SUBSTANTIALLY OVER THE LAST FEW HOURS IN RESPONSE TO STRENGTHENING LOW-LEVEL JET. SOME OF THIS HIGHER MOMENTUM AIR IS BEING MIXED TO THE GROUND AS EVIDENCED BY RECENT OBSERVATIONS AT KTCC. IT APPEARS THAT THE LOW-LEVEL JET IS BEGINNING TO EXPAND EASTWARD AS HEREFORD HAS RECENTLY REPORTED GUSTS UP TO 26 MPH. LATEST NAM...HRRR...AND RUC GUIDANCE CONTINUE TO SUGGEST THE STRONGEST WINDS WILL REMAIN SOUTH AND WEST OF A LINE FROM DALHART TO CLARENDON. BOTH THE RUC AND NAM SHOW THE 0-1 KM FLOW WILL BE 30-40 KT ACROSS THESE AREAS THROUGH 3 AM. HOWEVER...THE RUC REMAINS THE MOST AGGRESSIVE WITH THE WIND POTENTIAL OVERNIGHT...MAINLY DUE TO KEEPING THE NEAR-GROUND LAYER MIXED AND ALLOWING THE HIGHER MOMENTUM AIR TO BE TRANSPORTED DOWNWARD. THE NAM LARGELY KEEPS THE BOUNDARY LAYER DECOUPLED AND IS MUCH WEAKER WITH 0-1 KM LAPSE RATES. AM SOMEWHAT CONCERNED THAT SURFACE TEMPERATURES ACROSS EASTERN NEW MEXICO AND PARTS OF OLDHAM AND DEAF SMITH COUNTIES HAVE INCREASED WITHIN THE LAST HOUR. THIS SUGGESTS THAT THE NEAR-GROUND LAYER IS REMAINING MIXED AND THE RUC COULD BE ONTO SOMETHING. IF THE RUC VERIFIES...COULD SEE WINDS 25-35 MPH WITH GUSTS TO 45 MPH ACROSS THE SOUTHWESTERN TEXAS PANHANDLE. HOWEVER...BOTH THE NAM AND HRRR SUGGEST VERY LITTLE MIXING OVERNIGHT...WHICH SHOULD KEEP WINDS 20-25 MPH WITH GUSTS UP TO 35 MPH. ADDITIONALLY...LATEST MET GUIDANCE...WHICH HAD PREVIOUSLY BEEN AGGRESSIVE WITH THE WINDS...HAS BACKED OFF SIGNIFICANTLY. LEANED MORE HEAVILY TOWARDS THE NAM...HRRR...AND LATEST MET GUIDANCE...SO WE LOWERED WIND SPEEDS. STILL NOT EXPECTING WINDS TO BE STRONG ENOUGH TO REACH ADVISORY CRITERIA...BUT IT COULD STILL BE BREEZY TO WINDY AT TIMES THROUGH 3 AM. UPDATED PRODUCTS HAVE BEEN SENT. JACKSON PREV DISCUSSION... /ISSUED 540 PM CST WED JAN 18 2012/ AVIATION... BIGGEST AVIATION CONCERN WILL BE WIND SPEEDS TONIGHT...MAINLY BETWEEN 03Z AND 09Z THURSDAY. WINDS JUST ABOVE THE SURFACE EXPECTED TO INCREASE FROM THE WEST TO AROUND 40 TO 50 KNOTS BETWEEN 03Z AND 09Z THURSDAY...AND THE TUCUMCARI PROFILER SHOWED A 10 KNOT JUMP IN WIND SPEEDS BETWEEN 22Z AND 23Z WEDNESDAY AROUND THE THIRD AND FOURTH GATES. THE MAIN CONCERN WILL BE THE AMARILLO TAF WHERE SOME 40 KNOT OR HIGHER GUST MAY OCCUR JUST PRIOR TO 06Z THURSDAY...AND JUST AFTER 06Z THURSDAY. MAY NEED AN AVIATION WEATHER ADVISORY FOR THE AMARILLO AIRPORT TONIGHT FOR A BRIEF WINDOW...HOWEVER CONFIDENCE JUST A BIT TOO LOW AT THE MOMENT TO ISSUE. WILL CONTINUE TO MONITOR CLOSELY. OTHERWISE...VFR CONDITIONS WITH HIGH LEVEL CLOUDINESS THROUGH 00Z FRIDAY. WESTERLY TO SOUTHWESTERLY AND SOUTHERLY WINDS 10 TO 20 KNOTS WITH SOME HIGHER GUSTS POSSIBLE...THE EXCEPTION BEING BETWEEN 03Z AND 09Z THURSDAY AT THE AMARILLO TAF SITE. SCHNEIDER PREV DISCUSSION... /ISSUED 359 PM CST WED JAN 18 2012/ DISCUSSION... FOCUS OF THIS FORECAST REMAINS ON TEMPERATURES THROUGH THE WEEKEND...THEN SHIFTS TO PRECIPITATION PROSPECTS EARLY NEXT WEEK. A STRONG UPPER JET STRETCHED FROM THE PAC NW SOUTHEAST ACROSS THE NORTHERN ROCKIES INTO THE CENTRAL PLAINS THIS AFTERNOON. LEE ENHANCED CIRRUS ON THE SOUTH SIDE OF THE JET HAS PRODUCED A CIRRUS CANOPY ACROSS THE PANHANDLES TODAY...WHICH HAS BEEN FAIRLY THICK AT TIMES. THIS HAS DELAYED THE WARMUP TO SOME DEGREE TODAY...BUT A STEADY CLIMB THROUGH THE DAY HAS ALLOWED TEMPS TO REACH THE MID 50S TO LOWER 60S LATE THIS AFTERNOON. WEST/SOUTHWEST DOWNSLOPE WINDS TO THE EAST OF A LEE SURFACE TROUGH OVER EASTERN CO/NM HAVE AIDED THE WARMUP. A BREEZY TO WINDY AND RATHER MILD NIGHT FOR JANUARY IS EXPECTED FOR THE PANHANDLES TONIGHT. THE SURFACE TROUGH WILL ADVANCE EAST ACROSS THE AREA TONIGHT...SETTING UP A DECENT PRESSURE GRADIENT ACROSS WESTERN AND CENTRAL PORTIONS OF THE CWA. A WESTERLY 50 KT LLJ IS ALSO PROGGED TONIGHT. THUS...EXPECT BREEZY TO WINDY CONDITIONS THIS EVENING AND OVERNIGHT ACROSS WESTERN AND CENTRAL AREAS...WHICH WILL KEEP TEMPS UP. HAVE THUS GONE SEVERAL DEGREES ABOVE MOS GUIDANCE WITH FORECAST LOWS. CIRRUS MAY ALSO HOLD TEMPS UP A TAD...ALTHOUGH IT IS EXPECTED TO THIN LATER TONIGHT. WINDS WILL BE LIGHTER AND TEMPS COOLER ACROSS EASTERN AREAS MORE WITHIN THE SURFACE TROUGH AXIS. A COLD FRONT WILL BACK ITS WAY INTO THE AREA ON THURSDAY...SETTING UP A FAIRLY STRONG SOUTHWEST TO NORTHEAST TEMPERATURE GRADIENT OF ABOUT 20 DEGREES ACROSS THE CWA. THE PRESSURE GRADIENT WILL ALSO RELAX WITH THIS BOUNDARY PUSHING INTO THE AREA. WINDS MAY BE BREEZY ACROSS THE WEST/SOUTHWEST IN THE MORNING...BUT SHOULD DISSIPATE IN THE AFTERNOON. A ZONAL FLOW ALOFT WILL BE IN PLACE ACROSS THE CONUS ON FRIDAY. A FAST-MOVING MID/UPPER-LEVEL SHORTWAVE WILL MOVE EAST ACROSS THE CENTRAL PLAINS AND CLIP THE PANHANDLES FRIDAY AFTERNOON AND EVENING...SENDING A WEAK COLD FRONT SOUTH DURING THIS TIME AS WELL. STILL SOME SUBTLE TIMING DIFFERENCES WITH THE SHORTWAVE AND FRONT...WHICH ISN/T SURPRISING CONSIDERING THE FAST ZONAL FLOW. WILL SEE BREEZY TO WINDY WEST WINDS SOUTH OF THE FRONT...WITH WINDS DECREASING AND TURNING TO THE NORTH IN ITS WAKE. FRONTAL TIMING MAKES FOR A TRICKY TEMPERATURE FORECAST...BUT WILL AIM FOR LOWER 50S NORTHEAST TO AROUND 70F IN THE FAR SOUTH FOR NOW. LOW-LEVELS APPEAR WAY TOO DRY FOR THE SHORTWAVE TO SQUEEZE OUT ANY PRECIP. LEE TROUGHING WILL QUICKLY RE-DEVELOP ON SATURDAY BENEATH A CONTINUED ZONAL FLOW ALOFT. SOUTH/SOUTHWEST WINDS WILL RETURN IN RESPONSE...AND UNSEASONABLY WARM CONDITIONS WILL CONTINUE. ANOTHER SHORTWAVE WILL MOVE ACROSS SATURDAY NIGHT/SUNDAY...SENDING ANOTHER WEAK COLD FRONT THROUGH. AGAIN...THIS WAVE LOOKS TO BE MOISTURE STARVED AND THE FRONT WILL HAVE LITTLE EFFECT ON TEMPERATURES. WARM...DRY CONDITIONS TO PERSIST THROUGH MONDAY AHEAD OF THE NEXT UPPER TROUGH WORKING ACROSS THE WEST. THERE REMAINS QUITE A BIT OF UNCERTAINTY REGARDING THE POTENTIAL SYSTEM FOR EARLY TO MID NEXT WEEK. MODEL SOLUTIONS CONTINUE TO WAVER BETWEEN A CLOSED LOW AND A PROGRESSIVE OPEN WAVE AFFECTING THE PANHANDLES CENTERED ON THE TUESDAY TIMEFRAME. LATEST 12Z RUNS OF THE GFS AND ECMWF ARE BOTH NOW ADVERTISING AN OPEN WAVE AND ONLY MINIMAL PRECIPITATION CHANCES. WILL MAINTAIN SOME SMALL POPS TUESDAY ATTM...AND SEE HOW LATER RUNS TREND. DID WARM TEMPS SLIGHTLY ON TUESDAY AND TRIMMED THE RAIN/SNOW MIX BACK TO THE NORTHWEST. DRY BUT COOLER CONDITIONS THEN EXPECTED WEDNESDAY BEHIND THE DEPARTING UPPER TROUGH/LOW. KB FIRE WEATHER... A COLD FRONT WILL BACK INTO THE EASTERN OKLAHOMA PANHANDLE AND NORTHEAST TEXAS PANHANDLE ON THURSDAY...SETTING UP A SOUTHWEST TO NORTHEAST TEMPERATURE GRADIENT ACROSS THE AREA. THIS FRONT WILL ALSO KEEP WINDS LIGHTER...WITH SPEEDS EXPECTED TO REMAIN BELOW 15 MPH. THUS...ELEVATED FIRE WEATHER CONDITIONS ARE NOT EXPECTED DESPITE AFTERNOON RELATIVE HUMIDITIES FALLING TO 15 TO 20 PERCENT ACROSS THE SOUTHWEST HALF OF THE PANHANDLES. UNSEASONABLY WARM TEMPERATURES WILL CONTINUE INTO FRIDAY. WESTERLY WINDS WILL INCREASE AHEAD OF THE NEXT COLD FRONT...WHICH IS EXPECTED TO MOVE THROUGH DURING THE AFTERNOON OR EVENING HOURS. ELEVATED FIRE WEATHER CONDITIONS WILL BE POSSIBLE ACROSS THE SOUTHWEST HALF OF THE AREA...WITH CRITICAL CONDITIONS POSSIBLE ACROSS THE SOUTHWEST AND SOUTH CENTRAL TEXAS PANHANDLE WHERE WESTERLY WINDS WILL INCREASE TO 20 TO 30 MPH WITH HIGHER GUSTS AND MINIMUM RELATIVE HUMIDITIES WILL FALL TO 15 TO 20 PERCENT. A FIRE WEATHER WATCH HAS BEEN ISSUED FOR THESE AREAS. THERE IS STILL SOME UNCERTAINTY REGARDING TIMING OF THE COLD FRONT...AND A FASTER ARRIVAL COULD POTENTIALLY EASE FIRE WEATHER CONCERNS WHILE A SLOWER ARRIVAL MAY ALLOW CRITICAL CONDITIONS TO DEVELOP OVER A LARGER AREA. UNSEASONABLY WARM CONDITIONS WILL CONTINUE OVER THE WEEKEND INTO MONDAY. COMBINED WITH BREEZY CONDITIONS...ELEVATED FIRE WEATHER CONDITIONS WILL BE POSSIBLE SATURDAY THROUGH MONDAY ACROSS WESTERN AND CENTRAL PORTIONS OF THE AREA. KB && .AMA WATCHES/WARNINGS/ADVISORIES... TX...FIRE WEATHER WATCH FROM FRIDAY MORNING THROUGH FRIDAY EVENING FOR THE FOLLOWING ZONES: ARMSTRONG...CARSON...DEAF SMITH... OLDHAM...POTTER...RANDALL. OK...NONE. && $$ 11/13
AREA FORECAST DISCUSSION...UPDATED
NWS AMARILLO TX
1005 PM CST WED JAN 18 2012 .UPDATE... MAIN CHANGE WAS TO LOWER WIND SPEEDS TONIGHT...MAINLY ACROSS THE WESTERN AND SOUTHWESTERN TEXAS PANHANDLE. && .DISCUSSION... STILL A LOW CONFIDENCE FORECAST WITH RESPECT TO WIND SPEEDS OVERNIGHT. TUCUMCARI WIND PROFILER DATA INDICATES 0-1 KM FLOW HAS INCREASED SUBSTANTIALLY OVER THE LAST FEW HOURS IN RESPONSE TO STRENGTHENING LOW-LEVEL JET. SOME OF THIS HIGHER MOMENTUM AIR IS BEING MIXED TO THE GROUND AS EVIDENCED BY RECENT OBSERVATIONS AT KTCC. IT APPEARS THAT THE LOW-LEVEL JET IS BEGINNING TO EXPAND EASTWARD AS HEREFORD HAS RECENTLY REPORTED GUSTS UP TO 26 MPH. LATEST NAM...HRRR...AND RUC GUIDANCE CONTINUE TO SUGGEST THE STRONGEST WINDS WILL REMAIN SOUTH AND WEST OF A LINE FROM DALHART TO CLARENDON. BOTH THE RUC AND NAM SHOW THE 0-1 KM FLOW WILL BE 30-40 KT ACROSS THESE AREAS THROUGH 3 AM. HOWEVER...THE RUC REMAINS THE MOST AGGRESSIVE WITH THE WIND POTENTIAL OVERNIGHT...MAINLY DUE TO KEEPING THE NEAR-GROUND LAYER MIXED AND ALLOWING THE HIGHER MOMENTUM AIR TO BE TRANSPORTED DOWNWARD. THE NAM LARGELY KEEPS THE BOUNDARY LAYER DECOUPLED AND IS MUCH WEAKER WITH 0-1 KM LAPSE RATES. AM SOMEWHAT CONCERNED THAT SURFACE TEMPERATURES ACROSS EASTERN NEW MEXICO AND PARTS OF OLDHAM AND DEAF SMITH COUNTIES HAVE INCREASED WITHIN THE LAST HOUR. THIS SUGGESTS THAT THE NEAR-GROUND LAYER IS REMAINING MIXED AND THE RUC COULD BE ONTO SOMETHING. IF THE RUC VERIFIES...COULD SEE WINDS 25-35 MPH WITH GUSTS TO 45 MPH ACROSS THE SOUTHWESTERN TEXAS PANHANDLE. HOWEVER...BOTH THE NAM AND HRRR SUGGEST VERY LITTLE MIXING OVERNIGHT...WHICH SHOULD KEEP WINDS 20-25 MPH WITH GUSTS UP TO 35 MPH. ADDITIONALLY...LATEST MET GUIDANCE...WHICH HAD PREVIOUSLY BEEN AGGRESSIVE WITH THE WINDS...HAS BACKED OFF SIGNIFICANTLY. LEANED MORE HEAVILY TOWARDS THE NAM...HRRR...AND LATEST MET GUIDANCE...SO WE LOWERED WIND SPEEDS. STILL NOT EXPECTING WINDS TO BE STRONG ENOUGH TO REACH ADVISORY CRITERIA...BUT IT COULD STILL BE BREEZY TO WINDY AT TIMES THROUGH 3 AM. UPDATED PRODUCTS HAVE BEEN SENT. JACKSON && .PREV DISCUSSION... /ISSUED 540 PM CST WED JAN 18 2012/ AVIATION... BIGGEST AVIATION CONCERN WILL BE WIND SPEEDS TONIGHT...MAINLY BETWEEN 03Z AND 09Z THURSDAY. WINDS JUST ABOVE THE SURFACE EXPECTED TO INCREASE FROM THE WEST TO AROUND 40 TO 50 KNOTS BETWEEN 03Z AND 09Z THURSDAY...AND THE TUCUMCARI PROFILER SHOWED A 10 KNOT JUMP IN WIND SPEEDS BETWEEN 22Z AND 23Z WEDNESDAY AROUND THE THIRD AND FOURTH GATES. THE MAIN CONCERN WILL BE THE AMARILLO TAF WHERE SOME 40 KNOT OR HIGHER GUST MAY OCCUR JUST PRIOR TO 06Z THURSDAY...AND JUST AFTER 06Z THURSDAY. MAY NEED AN AVIATION WEATHER ADVISORY FOR THE AMARILLO AIRPORT TONIGHT FOR A BRIEF WINDOW...HOWEVER CONFIDENCE JUST A BIT TOO LOW AT THE MOMENT TO ISSUE. WILL CONTINUE TO MONITOR CLOSELY. OTHERWISE...VFR CONDITIONS WITH HIGH LEVEL CLOUDINESS THROUGH 00Z FRIDAY. WESTERLY TO SOUTHWESTERLY AND SOUTHERLY WINDS 10 TO 20 KNOTS WITH SOME HIGHER GUSTS POSSIBLE...THE EXCEPTION BEING BETWEEN 03Z AND 09Z THURSDAY AT THE AMARILLO TAF SITE. SCHNEIDER PREV DISCUSSION... /ISSUED 359 PM CST WED JAN 18 2012/ DISCUSSION... FOCUS OF THIS FORECAST REMAINS ON TEMPERATURES THROUGH THE WEEKEND...THEN SHIFTS TO PRECIPITATION PROSPECTS EARLY NEXT WEEK. A STRONG UPPER JET STRETCHED FROM THE PAC NW SOUTHEAST ACROSS THE NORTHERN ROCKIES INTO THE CENTRAL PLAINS THIS AFTERNOON. LEE ENHANCED CIRRUS ON THE SOUTH SIDE OF THE JET HAS PRODUCED A CIRRUS CANOPY ACROSS THE PANHANDLES TODAY...WHICH HAS BEEN FAIRLY THICK AT TIMES. THIS HAS DELAYED THE WARMUP TO SOME DEGREE TODAY...BUT A STEADY CLIMB THROUGH THE DAY HAS ALLOWED TEMPS TO REACH THE MID 50S TO LOWER 60S LATE THIS AFTERNOON. WEST/SOUTHWEST DOWNSLOPE WINDS TO THE EAST OF A LEE SURFACE TROUGH OVER EASTERN CO/NM HAVE AIDED THE WARMUP. A BREEZY TO WINDY AND RATHER MILD NIGHT FOR JANUARY IS EXPECTED FOR THE PANHANDLES TONIGHT. THE SURFACE TROUGH WILL ADVANCE EAST ACROSS THE AREA TONIGHT...SETTING UP A DECENT PRESSURE GRADIENT ACROSS WESTERN AND CENTRAL PORTIONS OF THE CWA. A WESTERLY 50 KT LLJ IS ALSO PROGGED TONIGHT. THUS...EXPECT BREEZY TO WINDY CONDITIONS THIS EVENING AND OVERNIGHT ACROSS WESTERN AND CENTRAL AREAS...WHICH WILL KEEP TEMPS UP. HAVE THUS GONE SEVERAL DEGREES ABOVE MOS GUIDANCE WITH FORECAST LOWS. CIRRUS MAY ALSO HOLD TEMPS UP A TAD...ALTHOUGH IT IS EXPECTED TO THIN LATER TONIGHT. WINDS WILL BE LIGHTER AND TEMPS COOLER ACROSS EASTERN AREAS MORE WITHIN THE SURFACE TROUGH AXIS. A COLD FRONT WILL BACK ITS WAY INTO THE AREA ON THURSDAY...SETTING UP A FAIRLY STRONG SOUTHWEST TO NORTHEAST TEMPERATURE GRADIENT OF ABOUT 20 DEGREES ACROSS THE CWA. THE PRESSURE GRADIENT WILL ALSO RELAX WITH THIS BOUNDARY PUSHING INTO THE AREA. WINDS MAY BE BREEZY ACROSS THE WEST/SOUTHWEST IN THE MORNING...BUT SHOULD DISSIPATE IN THE AFTERNOON. A ZONAL FLOW ALOFT WILL BE IN PLACE ACROSS THE CONUS ON FRIDAY. A FAST-MOVING MID/UPPER-LEVEL SHORTWAVE WILL MOVE EAST ACROSS THE CENTRAL PLAINS AND CLIP THE PANHANDLES FRIDAY AFTERNOON AND EVENING...SENDING A WEAK COLD FRONT SOUTH DURING THIS TIME AS WELL. STILL SOME SUBTLE TIMING DIFFERENCES WITH THE SHORTWAVE AND FRONT...WHICH ISN/T SURPRISING CONSIDERING THE FAST ZONAL FLOW. WILL SEE BREEZY TO WINDY WEST WINDS SOUTH OF THE FRONT...WITH WINDS DECREASING AND TURNING TO THE NORTH IN ITS WAKE. FRONTAL TIMING MAKES FOR A TRICKY TEMPERATURE FORECAST...BUT WILL AIM FOR LOWER 50S NORTHEAST TO AROUND 70F IN THE FAR SOUTH FOR NOW. LOW-LEVELS APPEAR WAY TOO DRY FOR THE SHORTWAVE TO SQUEEZE OUT ANY PRECIP. LEE TROUGHING WILL QUICKLY RE-DEVELOP ON SATURDAY BENEATH A CONTINUED ZONAL FLOW ALOFT. SOUTH/SOUTHWEST WINDS WILL RETURN IN RESPONSE...AND UNSEASONABLY WARM CONDITIONS WILL CONTINUE. ANOTHER SHORTWAVE WILL MOVE ACROSS SATURDAY NIGHT/SUNDAY...SENDING ANOTHER WEAK COLD FRONT THROUGH. AGAIN...THIS WAVE LOOKS TO BE MOISTURE STARVED AND THE FRONT WILL HAVE LITTLE EFFECT ON TEMPERATURES. WARM...DRY CONDITIONS TO PERSIST THROUGH MONDAY AHEAD OF THE NEXT UPPER TROUGH WORKING ACROSS THE WEST. THERE REMAINS QUITE A BIT OF UNCERTAINTY REGARDING THE POTENTIAL SYSTEM FOR EARLY TO MID NEXT WEEK. MODEL SOLUTIONS CONTINUE TO WAVER BETWEEN A CLOSED LOW AND A PROGRESSIVE OPEN WAVE AFFECTING THE PANHANDLES CENTERED ON THE TUESDAY TIMEFRAME. LATEST 12Z RUNS OF THE GFS AND ECMWF ARE BOTH NOW ADVERTISING AN OPEN WAVE AND ONLY MINIMAL PRECIPITATION CHANCES. WILL MAINTAIN SOME SMALL POPS TUESDAY ATTM...AND SEE HOW LATER RUNS TREND. DID WARM TEMPS SLIGHTLY ON TUESDAY AND TRIMMED THE RAIN/SNOW MIX BACK TO THE NORTHWEST. DRY BUT COOLER CONDITIONS THEN EXPECTED WEDNESDAY BEHIND THE DEPARTING UPPER TROUGH/LOW. KB FIRE WEATHER... A COLD FRONT WILL BACK INTO THE EASTERN OKLAHOMA PANHANDLE AND NORTHEAST TEXAS PANHANDLE ON THURSDAY...SETTING UP A SOUTHWEST TO NORTHEAST TEMPERATURE GRADIENT ACROSS THE AREA. THIS FRONT WILL ALSO KEEP WINDS LIGHTER...WITH SPEEDS EXPECTED TO REMAIN BELOW 15 MPH. THUS...ELEVATED FIRE WEATHER CONDITIONS ARE NOT EXPECTED DESPITE AFTERNOON RELATIVE HUMIDITIES FALLING TO 15 TO 20 PERCENT ACROSS THE SOUTHWEST HALF OF THE PANHANDLES. UNSEASONABLY WARM TEMPERATURES WILL CONTINUE INTO FRIDAY. WESTERLY WINDS WILL INCREASE AHEAD OF THE NEXT COLD FRONT...WHICH IS EXPECTED TO MOVE THROUGH DURING THE AFTERNOON OR EVENING HOURS. ELEVATED FIRE WEATHER CONDITIONS WILL BE POSSIBLE ACROSS THE SOUTHWEST HALF OF THE AREA...WITH CRITICAL CONDITIONS POSSIBLE ACROSS THE SOUTHWEST AND SOUTH CENTRAL TEXAS PANHANDLE WHERE WESTERLY WINDS WILL INCREASE TO 20 TO 30 MPH WITH HIGHER GUSTS AND MINIMUM RELATIVE HUMIDITIES WILL FALL TO 15 TO 20 PERCENT. A FIRE WEATHER WATCH HAS BEEN ISSUED FOR THESE AREAS. THERE IS STILL SOME UNCERTAINTY REGARDING TIMING OF THE COLD FRONT...AND A FASTER ARRIVAL COULD POTENTIALLY EASE FIRE WEATHER CONCERNS WHILE A SLOWER ARRIVAL MAY ALLOW CRITICAL CONDITIONS TO DEVELOP OVER A LARGER AREA. UNSEASONABLY WARM CONDITIONS WILL CONTINUE OVER THE WEEKEND INTO MONDAY. COMBINED WITH BREEZY CONDITIONS...ELEVATED FIRE WEATHER CONDITIONS WILL BE POSSIBLE SATURDAY THROUGH MONDAY ACROSS WESTERN AND CENTRAL PORTIONS OF THE AREA. KB && .AMA WATCHES/WARNINGS/ADVISORIES... TX...FIRE WEATHER WATCH FROM FRIDAY MORNING THROUGH FRIDAY EVENING FOR THE FOLLOWING ZONES: ARMSTRONG...CARSON...DEAF SMITH... OLDHAM...POTTER...RANDALL. OK...NONE. && $$ KS/JJ
AREA FORECAST DISCUSSION...UPDATED
NWS MILWAUKEE/SULLIVAN WI
916 PM CST FRI JAN 20 2012 .UPDATE... LAKE EFFECT SNOW BAND HAS SET UP RIGHT ALONG RACINE/MILWAUKEE COUNTY LINE. DELTA T VALUES ARE ABOUT 16. VAD WIND FROM KMKE TDWR HAS NORTHEAST 925 MB WIND AT 15 KNOTS...BUT MOST GUIDANCE SHOWS 25 KNOTS OVER CENTRAL LAKE MICHIGAN. NICE CONVERGENCE SHOWN IN SURFACE OBSERVATIONS WITH NORTHWEST WIND AND 12F AT KMKE WITH 23F AND EAST WIND AT KRAC. WRF NMM 4KM FROM NCEP SHOWS 0.45" OF LIQUID OVER EASTERN RACINE COUNTY FROM 06Z TO 18Z SATURDAY. DECIDED TO GO WITH AMOUNTS ROUGHLY HALF THAT AND COMPROMISE BETWEEN LOCAL 4KM WRF AND HRRR SO ROUGHLY 2 TO 4 INCHES IN EASTERN RACINE AND KENOSHA COUNTIES AND AN INCH OR TWO IN FAR SOUTHEAST MILWAUKEE COUNTY NEAR OAK CREEK BEFORE THE BAND SHIFTS SLOWLY SOUTH ALONG THE LAKE SHORE. MAY HAVE TO ADD MILWAUKEE COUNTY IF BAND DOES NOT SHIFT BUT FEEL THAT CITY OF MILWAUKEE PROBABLY SAFE FROM ACCUMULATING SNOW. && .AVIATION/06Z TAFS/... LAKE EFFECT SNOW BAND HAS SET UP BETWEEN KMKE AND KENW TAF SITES. SHOULD STAY SOUTH OF KMKE BUT CEILINGS ARE NOW IFR AND MAY PERSIST FOR A WHILE UNTIL BAND SHIFTS FARTHER SOUTH. IFR VISIBILITIES IN SNOW SHOWERS ALSO LIKELY EVENTUALLY AT KENW AS BAND SHIFTS SOUTH. ELSEWHERE MVFR CEILINGS AT KUES SHOULD EVENTUALLY IMPROVE AND VFR CEILINGS AT KMSN. WINDS SHOULD BE LIGHT BUT MAY COME UP LATER SATURDAY NIGHT AND THERE IS POTENTIAL FOR ADVECTION STRATUS BUT A BIT TOO LOW TO MENTION IN TAFS AT THIS POINT. && .MKX WATCHES/WARNINGS/ADVISORIES... WI...LAKE EFFECT SNOW ADVISORY UNTIL 6 AM CST SATURDAY FOR WIZ071-072. LM...NONE. && $$ UPDATE...CRAVEN
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
320 PM CST THU JAN 19 2012 .SHORT TERM...TONIGHT THROUGH SUNDAY 320 PM CST THU JAN 19 2012 MAIN FORECAST CONCERNS ARE ON THE ACCUMULATING SNOW EVENT FOR LATE TONIGHT INTO FRIDAY...AS WELL AS A MIXED PRECIPITATION EVENT FOR SUNDAY. CURRENTLY AS OF 21Z...WATER VAPOR LOOP AND RUC 500MB HEIGHT ANALYSIS SHOWED A WEST-NORTHWEST FLOW FROM THE PACIFIC NORTHWEST INTO THE OHIO VALLEY WITH A TROUGH OVER THE WESTERN GREAT LAKES REGION. ALSO NOTED ON WATER VAPOR IS A SHORTWAVE TROUGH JUST OFF THE COAST OF OREGON. FAST JET STREAM IN THE WEST-NORTHWEST FLOW...WITH THE RUC TROPOPAUSE WIND SPEEDS SHOWING 130-160KT FROM FAR SOUTHERN SASKATCHEWAN INTO FAR WESTERN KENTUCKY. WITH THE FORECAST AREA ON THE NORTHEAST/SUBSIDENT SIDE OF THE UPPER JET AND ON THE BACK SIDE OF THE WESTERN GREAT LAKES TROUGH...HIGH PRESSURE IS FAVORED AT THE SURFACE. THIS HIGH IS CENTERED OVER SOUTHERN MINNESOTA AND IOWA. ARCTIC AIR REMAINS IN PLACE...NOTED BY SURFACE TEMPERATURES ONLY JUST ABOVE ZERO...DESPITE PLENTY OF SUN. 12Z SOUNDING PLOT OF 850MB TEMPERATURES REFLECTIVE OF BOTH THE ARCTIC AIR AND THE FAST UPPER JET...WITH READINGS OF -21 TO -25C AT ABR...MPX AND GRB WHILE ONLY -9C AT OAX AND -12C AT DVN. A SIMILAR DRAMATIC DIFFERENCE CAN BE SEEN IN PRECIPITABLE WATER PLOTS. ABR...MPX AND GRB HAD READINGS OF 0.05 TO 0.1 INCHES OR 20-30 PERCENT OF NORMAL...WHILE DVN AND OAX REPORTED 0.26 INCHES OR ALMOST 100 PERCENT OF NORMAL. LAST ITEM OF NOTE IS A FRONTOGENETIC BAND OF SNOW OVER CENTRAL MONTANA. THIS AREA OF FRONTOGENESIS IS ALONG THE WESTERN EXTENT OF THE AFOREMENTIONED SHARP CONTRAST IN MOISTURE/850MB TEMPS. TONIGHT AND FRIDAY...UPPER LEVEL FLOW IS PROGGED TO TURN MORE WESTERLY/ZONAL DURING THE NEXT 24 HOURS...MOSTLY IN RESPONSE TO THE TROUGH OFF THE OREGON COAST RAPIDLY MOVING INLAND. THIS TROUGH IS VERY IMPORTANT TO THE FORECAST AND SPECIFICALLY HOW AMPLIFIED IT IS AS IT MOVES THROUGH THE CENTRAL PLAINS ON FRIDAY. THE REASON IS THAT AS THE DPVA AND WARM ADVECTION APPROACHES AHEAD OF THE TROUGH...THE SHARP CONTRAST IN TEMPERATURES AND MOISTURE NOTED IN THE CURRENT DISCUSSION WILL LIGHT UP WITH SNOW. ANOTHER FEATURE HELPING TO PRODUCE THE SNOW WILL END UP BEING A RIGHT ENTRANCE REGION OF THE CURRENT STRONG UPPER JET...WHICH LIFTS NORTHEAST TONIGHT AND FRIDAY WITH THE CHANGE IN UPPER FLOW. THEREFORE...WHERE THIS SNOW BAND SETS UP AND HOW STRONG DEPENDS ON THE AMPLITUDE OF THE TROUGH. RUN TO RUN THE NAM HAS BEEN THE MOST POTENT WITH THIS TROUGH...THOUGH IT HAS SPED UP SOME TO COME IN CLOSER WITH THE CONSENSUS WITH THE 19.12Z RUN. THE CANADIAN HAS BEEN CONSISTENTLY SHOWING A LESS POTENT TROUGH...KEEPING THE HEAVIER BAND MOSTLY SOUTH OF THE FORECAST AREA...THOUGH THE LATEST 19.12Z RUN SHOWED A SLIGHT NORTHWARD DRIFT. THE GFS REMAINS A CONSISTENT COMPROMISE APPROACH BETWEEN THE CANADIAN AND NAM. ANOTHER ISSUE TO DEAL WITH REMAINS SNOW RATIOS. A FLATTER SOLUTION ALLOWS FOR A SLOWER EXIT OF THE CURRENT ARCTIC AIR...SETTING THE STAGE FOR A DEEPER DENDRTIC SNOW GROWTH LAYER. THIS IS ESPECIALLY TRUE FOR ABOUT THE NORTHERN TWO THIRDS OF THE FORECAST AREA...WHERE 20 TO 1 SNOW RATIOS ARE LIKELY...NO MATTER WHAT SOLUTION IS FOLLOWED. ON THE OTHER HAND...THE MORE AMPLIFIED SOLUTION LIKE THE NAM ADVECTS WARMER MID LEVEL AIR INTO THE SOUTHERN THIRD OF THE FORECAST AREA...DECREASING THE DENDRITIC GROWTH ZONE. AROUND 15 TO 1 RATIOS WOULD BE MORE REASONABLE IN THIS ZONE. IN TERMS OF TIMING...GOOD CONSENSUS FOR THE SNOW TO MOVE INTO AREAS WEST OF THE MISSISSIPPI RIVER BETWEEN 09-12Z...OVERSPREAD MUCH OF THE AREA FOR 12-18Z WHICH ALSO LOOKS TO BE THE HEAVIEST SNOW TIME...THEN BEGIN TO EXIT WEST TO EAST BETWEEN 18-00Z. TRICKY DETERMINING THE HAZARD SCENARIO WITH QUESTIONS ON THE SNOW TO WATER RATIO AS WELL AS PLACEMENT OF THE HEAVIER BAND. HIGH CERTAINTY THAT LOCATIONS ALONG AND SOUTH OF I-90 WILL SEE ADVISORY CRITERIA. NOT ENOUGH CERTAINTY EXISTS TO PLACE ANY WARNINGS...THOUGH...WITH THE UNCERTAINTY ON MAX QPF PLACEMENT...FORCING AND SNOW TO WATER RATIOS. 19.15Z SREF PLUMES ALSO SHOWS A LARGE AMOUNT OF UNCERTAINTY REGARDING AMOUNTS. FUTURE SHIFTS MAY UPGRADE TO WARNINGS IF THE ZONE OF HEAVIEST QPF CAN BE NARROWED DOWN. QUICKLY REGARDING TEMPERATURES...SHOULD SEE LOWS THIS EVENING THEN READINGS RISE AFTER MIDNIGHT TONIGHT INTO FRIDAY WITH THE CLOUDS/WARM ADVECTION MOVING IN. FRIDAY NIGHT AND SATURDAY...SHORTWAVE TROUGH THAT MOVED INTO THE CENTRAL PLAINS FRIDAY CONTINUES HEADING RAPIDLY OFF TO THE EAST FRIDAY NIGHT...ALLOWING HIGH PRESSURE TO BUILD OVER THE ENTIRE AREA BY SATURDAY MORNING. SKIES LOOK TO CLEAR AS THE HIGH MOVES IN...THEREFORE...WITH THE FRESH SNOW WENT TOWARDS THE LOW END OF GUIDANCE FOR LOWS. FOR SATURDAY...MODELS ARE IN GOOD AGREEMENT BRINGING A DEEP TROUGH INTO THE WESTERN U.S. AS THIS OCCURS... HEIGHTS BUILD DOWNSTREAM OVER THE FORECAST AREA...RESULTING IN FAIRLY STRONG WARM ADVECTION BY THE END OF THE DAY. 850MB TEMPS CLIMB FROM -8 TO -12C AT 12Z SATURDAY TO -2 TO -6C BY 00Z SUNDAY. NOT ANTICIPATING ANY PRECIPITATION ON SATURDAY...DUE TO THE DRY HIGH PRESSURE AREA STILL IN PLACE...THOUGH AN INCREASE OF MID AND HIGH CLOUD COVER IS LIKELY AS THE DAY GOES ON. GENERALLY FOLLOWED A BLEND OF GUIDANCE FOR HIGHS. SATURDAY NIGHT AND SUNDAY...FOCUS OF ATTENTION IS ON THAT NEXT DEEP TROUGH IN THE WESTERN U.S. AT 00Z SUNDAY. DPROG/DT OF ALL MODELS SHOWS THIS TROUGH TRENDING RAPIDLY DEEPER AND SLOWING SOMEWHAT. RIGHT NOW MOST MODELS ARE IN AGREEMENT OF THE TROUGH MOVING INTO THE PLAINS ON SUNDAY. ALSO OF NOTE IS THAT A POTENT SHORTWAVE IS INDICATED AT THE BOTTOM OF THE TROUGH...WHICH MAY TURN NEGATIVE TILT AS IT LIFTS UP THE EAST SIDE OF THE TROUGH TOWARDS THE FORECAST AREA LATE SUNDAY AND INTO SUNDAY NIGHT. THIS MEANS THE WEATHER IS GOING TO BE ACTIVE AGAIN...BUT THIS TIME THE TROUGH HAS A SURGE OF WARM AND MORE MOIST AIR FROM THE GULF OF MEXICO...RESULTING IN ISSUES WITH PRECIPITATION TYPE. FIRST FOR SATURDAY NIGHT...WARM ADVECTION DOWNSTREAM SHOULD ALLOW TEMPERATURES TO CLIMB THROUGH THE NIGHT. ANY PRECIPITATION ASSOCIATED WITH THE WARM ADVECTION LOOKS TO STAY OFF TO OUR NORTHWEST...MAINLY OVER WESTERN AND NORTHERN MINNESOTA. BETTER SHOT FOR PRECIPITATION EXISTS ON SUNDAY...ESPECIALLY IN THE AFTERNOON...AS HEIGHT FALLS FROM THE UPPER TROUGH AND ISENTROPIC LIFT AHEAD OF THE TROUGH MOVES INTO THE AREA. WITH THE PERSISTENT WARM ADVECTION...2 METER TEMPERATURES ARE LIKELY TO CLIMB ABOVE FREEZING FOR MOST OF THE AREA...RESULTING IN POTENTIAL FOR A MIX/CHANGE TO RAIN AND SNOW. WITH GROUND AND SNOW TEMPERATURES PROBABLY STAYING BELOW FREEZING...THIS RAIN COULD TURN TO ICE ON UNTREATED ROADS...THUS THE INTRODUCTION OF FREEZING RAIN TOO INTO THE FORECAST. NOTE...THERE IS A MID LEVEL DRY AIR LAYER NOTED IN SOUNDINGS...THOUGH IT DOES NOT LOOK TO BE DEEP ENOUGH OR DRY ENOUGH AT THIS TIME TO PREVENT ICE FROM ALOFT REACHING DOWN TO THE SURFACE. .LONG TERM...SUNDAY NIGHT THROUGH THURSDAY 320 PM CST THU JAN 19 2012 UPPER TROUGH OVER THE PLAINS LOOKS TO LIFT NORTHEAST THROUGH THE AREA SUNDAY NIGHT AND AWAY FROM THE AREA ON MONDAY. CERTAINLY THIS BEARS WATCHING FOR TIMING GIVEN THE TREND FOR THIS TROUGH TO BE AMPLIFIED AND SLOWER. IN FACT THE NEW 19.12Z ECMWF SLOWED DOWN THE TROUGH A BIT MORE. SHOULD SEE ANY RAIN/FREEZING RAIN CHANGE OVER TO SNOW THROUGH THE NIGHT SUNDAY NIGHT...WITH ALL SNOW MONDAY...THOUGH AGAIN THE PRECIPITATION SHOULD BE WINDING DOWN MONDAY. MAY HAVE TO WATCH FOR POTENTIAL ADVISORY SNOW SUNDAY NIGHT...AND POSSIBLY INTO MONDAY IF THE NEW ECMWF IS CORRECT. REST OF NEXT WEEK CONTINUES TO SHOW A SOMEWHAT ACTIVE PATTERN...WITH MODELS IN VERY GOOD AGREEMENT SHOWING SHORTWAVE TROUGHS MOVING THROUGH TUESDAY NIGHT INTO WEDNESDAY...AS WELL AS ON THURSDAY. HOWEVER...NONE OF THESE TROUGHS LOOK TO HAVE A LOT OF MOISTURE WITH THEM...LIKELY SHUNTED OFF BY THE DEEPER SUNDAY NIGHT/MONDAY TROUGH. FOLLOWED A CONSENSUS APPROACH GIVEN THE GOOD AGREEMENT...RESULTING IN MOSTLY 20-40 PERCENT CHANCES FOR THESE TROUGHS. TEMPERATURES WILL BE WARMER NEXT WEEK THAN THIS WEEK...THANKS TO THE MAIN POLAR WESTERLIES SHIFTING WELL NORTH INTO CANADA. IT DOES NOT APPEAR THAT ENOUGH WARM AIR ENTERS ANY OF THE TROUGHS TO RESULT IN LIQUID PRECIPITATION...THOUGH. && .AVIATION...THROUGH 18Z FRIDAY 1134 AM CST THU JAN 19 2012 SHORT WAVE TROUGH COMING ON TO THE PACIFIC NORTHWEST COAST WILL QUICKLY MOVE ACROSS THE ROCKIES AND INTO THE MIDWEST BY LATE TONIGHT. THE 19.12Z NAM AND GFS ARE BOTH IN AGREEMENT THAT THE WAVE WILL BE MOVING RAPIDLY WITH LITTLE CHANCE FOR AMPLIFICATION AS IT COMES THROUGH WITH A POSITIVE TILT. THIS WILL BRING A NARROW AND QUICK SHOT OF 12 TO 16 PVU/S OF PV ADVECTION IN THE 500-300 MB LAYER FRIDAY MORNING. THERE WILL BE SOME WEAK TO MODERATE FRONTOGENESIS THAT SETS UP IN THE 850-500 MB LAYER FOR FRIDAY MORNING AND COMBINED WITH 2 TO 4 UBAR/S OF UP GLIDE ON THE 280 THROUGH 290K ISENTROPIC SURFACES...THERE WILL BE ENOUGH FORCING TO PRODUCE A PERIOD OF SNOW FOR BOTH TAF SITES. VFR CONDITIONS WILL PREVAIL UNTIL THE SNOW STARTS AND SHOULD THEN SEE AN ABRUPT DROP TO IFR FOR BOTH THE VISIBILITY AND CEILINGS. FORCING COULD BE STRONG ENOUGH TO PRODUCE A 3 TO 4 HOUR PERIOD OF VISIBILITIES DOWN TO ABOUT A MILE WITH SUB 1000 FOOT CEILINGS. EXPECTING THE SNOW TO START IN THE 10 TO 12Z TIME FRAME WITH THE WORST CONDITIONS EXPECTED A COUPLE OF HOURS AFTER THE SNOW INITIALLY BEGINS. APPEARS AS FAST THE SNOW COMES IN...IT WILL ALSO END...BUT THIS IS NOT EXPECTED TO OCCUR UNTIL AFTER 18Z FRIDAY. && .ARX WATCHES/WARNINGS/ADVISORIES... 320 PM CST THU JAN 19 2012 WI...WINTER WEATHER ADVISORY FROM 6 AM TO 6 PM CST FRIDAY FOR WIZ041>044-053>055-061. MN...WINTER WEATHER ADVISORY FROM 3 AM TO 6 PM CST FRIDAY FOR MNZ086>088-094>096. IA...WINTER WEATHER ADVISORY FROM 3 AM TO 6 PM CST FRIDAY FOR IAZ008>011-018-019-029-030. && $$ SHORT TERM...AJ LONG TERM...AJ AVIATION...04
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
303 AM CST SAT JAN 21 2012 .DISCUSSION... 910 PM CST ALL ILLINOIS COUNTIES ARE CLEARED FROM ANY WINTER HEADLINES...WITH INDIANA TO BE FOLLOWING SUIT SHORTLY. STILL SOME LIGHT SNOW SHOWERS TO FLURRIES PERSIST FROM ROUGHLY THE I-57 CORRIDOR AND EAST... BUT OVERALL TRENDS CONTINUE TO DECREASE...AND QUICKLY. FOCUS ON THE OVERNIGHT WILL THEN TURN TO THE POTENTIAL FOR LAKE EFFECT SNOWS WITH A CONVERGENT BOUNDARY THAT IS NOTED ON TMKE FROM EAST OF MILWAUKEE...SOUTHWEST TO ROUGHLY KRAC. HIGH RESOLUTION GUIDANCE HAS BEEN CONSISTENT IN TAKING THE BOUNDARY AND SWINGING IT SOUTH...IMPACTING THE COASTAL CITIES. 850 TO LAKE SURFACE DELTA T/S LOOK SUPPORTIVE FOR A SHORT TIME...AND ALL GUIDANCE KEEPS THE PRESENT CONVERGENT BOUNDARY AND SUBSEQUENT LES PRESENT INTO THE AFTERNOON. NO REAL CHANGE TO THE THINKING FROM DAY SHIFT AND WILL ONLY MAINTAIN THE SLIGHT CHANCE POPS FOR COASTAL LOCATIONS. NOT EXPECTING MUCH ADDITIONAL SNOWFALL WITH THESE SHOWERS...AND AMOUNTS LESS THAN AN INCH. SHEA //PREV DISCUSSION... 655 PM CST THE HEAVIEST OF SNOWFALL IS BEGINNING TO SHIFT EAST OF THE AREA WITH MOST LOCATIONS AT OR ABOVE 1/2 TO 1 MILE VIS. THE EARLIER HEAVY BANDING LINED UP NICELY WITH AN AREA OF RUC ANALYZED FGEN WITHIN THE H85 TO H7 LAYER. THAT AREA WILL CONTINUE TO WEAKEN AND SHIFT EAST - AND NOT EXPECTING ANY FURTHER SIGNIFICANT REDUCTIONS TO VIS OR INCH PER HOUR SNOWFALL THOUGH THE EVENING. THE BACK EDGE OF THE PRECIP IS NOTED BASICALLY NOTED FROM WHITEWATER WISCONSIN...SOUTHWEST THROUGH FREEPORT ILLINOIS. PRESENT WSW GOES THROUGH 03Z FOR THE NORTHWESTERN TIER OF COUNTIES...AND MAY BEGIN TO PULL COUNTIES EARLIER AS THE BACK EDGE MOVES THROUGH. FOR COUNTIES EAST...STILL EXPECT THE SNOWFALL TO DECREASE THROUGH THE EVENING WITH ONLY MINOR ACCUMULATIONS FOR AREAS WEST OTHE 355/57 CORRIDOR...AND ANOTHER INCH OR SO FOR LOCATIONS ALONG THE ILLINOIS/INDIANA BORDER AND EAST. SHEA .PREVIOUS DISCUSSION... 344 PM CST NO MAJOR SURPRISES SO FAR...DID EXPAND THE WINTER STORM WARNING INTO LEE COUNTY THIS AFTERNOON WHICH HAS SEEN PROLONGED PERIOD OF HEAVIER SNOWFALL WITH DECENT RETURNS STILL UPSTREAM. KENDALL AND WILL COUNTIES WILL BE CLOSE TO WARNING CRITERIA OF 6" AS AXIS OF MAXIMUM SNOW SETS UP PRETTY MUCH AS EXPECTED BETWEEN THE I-90 AND I-80 CORRIDORS WITH RATES OF AN INCH AN HOUR...OCCASIONALLY 1.5 INCHES PER HOUR. EXPECT INTENSITIES TO PEAK ACROSS THE CHICAGO METRO AREA THROUGH THE EARLY EVENING. DID GET OFF TO A SLOWER START THAN EXPECTED AND SNOW:LIQUID RATIOS HAVE BEEN A BIT LOWER THAN ORIGINALLY ANTICIPATED...SO FOR NOW BELIEVE DESPITE THE AXIS SETTING UP FARTHER SOUTH THAN THE ORIGINAL WARNING AREA...THAT ADVISORY FOR 4 TO 6 INCHES ACROSS KENDALL/WILL COUNTIES AND LAKE COUNTY INDIANA WILL STAND //THOUGH MAY SEE SOME LOCALIZED AREAS AT OR JUST ABOVE 6 INCHES PARTICULARLY ACROSS FAR NORTHERN WILL COUNTY//. WIDESPREAD VSBY OF 1/4 MILE OR LESS HAS BEEN REPORTED AND INTERMITTENT PERIODS OF HEAVY SNOW CONTINUE SO ROADWAYS WILL BE A MESS THROUGH THE EVENING HOURS. SATURDAY THROUGH FRIDAY... SHORT TERM...SATURDAY THROUGH MONDAY...FOLLOWING THE PASSAGE OF THE MID LEVEL SYSTEM RESPONSIBLE FOR THE SYNOPTIC SNOW...THE INITIAL FORECAST CONCERN WILL FOCUS ON THE POTENTIAL FOR A LAKE EFFECT BAND OF SNOW MOVING INTO NERN IL. ALL OF THE GUIDANCE IS INDICATING LAKE SFC-850MB DELTA-T AROUND 15C OVER SOUTHERN LAKE MICHIGAN...WHICH WOULD BE CONDUCIVE TO LAKE EFFECT SNOW DEVELOPMENT. THE HIGH RES WRF-ARW/NMM WITH SUPPORT OF THE OPERATIONAL NAM12...ALL INDICATE A CONVERGENCE BAND FORMING OVER SOUTHERN LAKE MICHIGAN...WITH THE POSSIBILITY OF MESOVORTEX DEVELOPMENT WITHIN THE CONVERGENCE ZONE AND INVERTED TROUGH. WITH TIME...THE BAND SHOULD GRADUALLY MOVE INLAND AND TO THE NORTHWEST...POSSIBLE AFFECTING PORTIONS OF NERN AND NCNTRL IL. CONCURRENTLY...LAKE SFC-850MB DELTA T VALUES WILL BE ON THE DECREASE. SO...EXPECT MORE OF AN ADVECTING BAND OF LAKE EFFECT SNOW THAN CONTINUOUS PRODUCTION OF LAKE EFFECT SNOW OVER THE IMMEDIATE LAKE FRONT LOCATIONS. AT THIS TIME...HAVE OPTED TO DEPICT THIS LAKE EFFECT BAND IN THE GRIDDED FORECAST GRAPHICS WITH AN AREA OF CHANCE TO SLIGHT CHANCE POPS WITH -SHSN. THERE IS CERTAINLY THE POTENTIAL FOR ADDITIONAL ACCUMULATING SNOW WITH THE MAIN CONVERGENCE AREA...BUT DUE TO THE MESOSCALE NATURE OF ANY POSSIBLE MESOVORTEX DEVELOPMENT...IT IS NOT POSSIBLE TO PINPOINT ANY POSSIBLE HEAVIER LAKE EFFECT SNOW WITH THIS FEATURE...WHICH WOULD NEED TO BE HANDLED WITH A NEAR TERM FORECAST UPDATE TOMORROW. ON A LARGER SCALE...HIGH PRESSURE SHOULD BUILD OVER THE AREA BRINGING DECREASING CLOUD COVER. TO START OUT SATURDAY MORNING...TEMPERATURES SHOULD RANGE FROM THE LOWER SINGLE DIGITS OVER THE NWRN PORTIONS OF THE CWA...WHERE SKIES SHOULD CLEAR THE EARLIEST AND THE GREATEST AMOUNT OF RADIATING SHOULD OCCUR...TO THE UPPER TEENS ALONG THE LAKE FRONT...WHERE THERE SHOULD BE THE GREATEST AMOUNT OF RESIDUAL CLOUD COVER. WITH AT LEAST PARTIAL SUNSHINE AND AN END TO SUSTAINED COLD ADVECTION OVER THE AREA ON SATURDAY...TEMPERATURES SHOULD SHOULD REBOUND INTO THE LOWER TO MIDDLE 20S. BY SUNDAY...THE HIGH WILL MOVE OFF TO THE EAST. A MORE COMPLICATED SITUATION WILL BE SETTING UP TO THE WEST OF THE LOCAL AREA BY SUNDAY. STRONG NORTHERN AND SOUTHERN STREAM SHORTWAVES ARE EXPECTED TO EJECT OUT OF THE ROCKIES BY SUNDAY MORNING...WITH A LARGE AREA OF LOW PRESSURE DEVELOPING OVER THE CENTRAL PLAINS. THIS WILL INITIATE STRONG WARM/MOIST ADVECTION INTO THE MIDWEST. THE MODELS ARE INDICATING PHASING OF THE NORTHERN AND SOUTHERN STREAMS...WITH A CONSOLIDATED SFC LOW FORMING OVER LOWER MICHIGAN BY MONDAY MORNING. THE MAIN CHANGE TO THE GOING FORECAST WITH RESPECT TO THIS SYSTEM IS TO SPEED UP THE PROGRESSION WITH A COLD FRONTAL PASSAGE LATE SUNDAY NIGHT OR EARLY MONDAY MORNING. WITH THE STRONG WARM ADVECTION...ASSOCIATED PCPN WILL START OUT IN LIQUID FORM AS TEMPERATURES CLIMB INTO THE UPPER 30S TO LOWER 40S THROUGH THE DAY...WITH TEMPERATURES REMAINING NEARLY STEADY INTO THE NIGHT. TEMPERATURES WILL NOT DROP OFF UNTIL AFTER THE FROPA...WHEN TEMPERATURES WILL DROP INTO THE LOWER 20S OVER THE ROCKFORD AREA. FARTHER SOUTHEAST...SOUTH OF THE KANKAKEE VALLEY...TEMPS WILL ONLY DROP INTO THE MIDDLE 30S SO A CHANGEOVER FROM RAIN TO SNOW MAY NOT OCCUR UNTIL LATE IN THE DAY. IT IS EVEN POSSIBLE THAT TEMPS OVER BENTON/JASPER/NEWTON COUNTY AREA MAY NOT COOL OFF ENOUGH BEFORE THE SYSTEM LIFTS OUT LATE MONDAY TO EVER SEE ANY ADDITIONAL SNOW. EXTENDED FORECAST...TUESDAY THROUGH FRIDAY...CONDITIONS SHOULD QUIET DOWN CONSIDERABLY THROUGH THE EXTENDED FORECAST PERIOD. BY TUESDAY...HIGH PRESSURE WILL ONCE AGAIN DOMINATE THE REGION. A SPLIT FLOW PATTERN IS EXPECTED TO DEVELOP WITH AN ACTIVE NORTHERN STREAM FOCUSED ALONG THE CANADIAN BORDER WHILE AN ACTIVE SOUTH STREAM WILL BE FOCUSED ALONG THE RED RIVER VALLEY AND OHIO VALLEY. IN BETWEEN THESE TWO STREAMS...THE MIDDLE MISSISSIPPI VALLEY AND MIDWEST WILL REMAIN UNDER A WEAK RIDGE OF HIGH PRESSURE. THE BEST CHANCE FOR ANY PCPN BETWEEN EARLY TUESDAY AND EARLY FRIDAY WILL BE ON WEDNESDAY WHEN THE NRN STREAM SYSTEM WILL BE PASSING THROUGH THE UPPER GREAT LAKES AND STRONG WARM ADVECTION DEVELOPS OVER THE LOWER AND MIDDLE MISSISSIPPI VALLEY AND SPREADING INTO SOUTHERN IL/IN. BETWEEN THESE TWO SYSTEM...THERE IS A CHANCE FOR SOME LIGHT RAIN OVER THE SOUTHERN PORTIONS OF THE CWA...WITH SOME LIGHT SNOW POSSIBLE OVER THE NRN LOCATIONS. THERE MAY BE A BRIEF TRANSITION OVER TO ALL LIGHT SNOW WEDNESDAY NIGHT...BEFORE THE NRN STREAM SYSTEM SCOOTS OFF TO THE EAST. THE NEXT SIGNIFICANT CHANCE FOR PCPN WILL NOT BE UNTIL LATE IN THE EXTENDED PERIOD...AND WILL BE ASSOCIATED WITH THE SRN STREAM SYSTEM. THE GFS AND ECMWF ARE IN DECENT ENOUGH AGREEMENT ON THIS SYSTEM...THOUGH THE ECMWF IS A BIT FASTER AND HAS A GREATER DEGREE OF PHASING WITH THE NRN STREAM THAN THE GFS...WHICH INDICATES MORE OF A CUT OFF LOW AND...CONSEQUENTLY... IS MORE SLOWLY PROGRESSIVE. DEPENDING ON WHETHER THE FASTER OR THE SLOW SOLUTION VERIFIES...WE COULD SEE PCPN MOVING BACK INTO THE AREA AS EARLY AS THURSDAY PER THE ECMWF OR FRIDAY PER THE GFS. AT THIS POINT...HAVE GONE WITH A MORE MIDDLE OF THE ROAD APPROACH FOR THE LATE EXTENDED PERIOD POPS...WITH SLIGHT CHANCE POPS FOR THURSDAY NIGHT AND CHANCE POPS FOR FRIDAY. KREIN && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 09Z... * MVFR CIGS LINGERING THROUGH THE MORNING. * POTENTIAL FOR LIGHT LAKE EFFECT SNOW SHOWERS AFT 10Z FOR A FEW HOURS. * IMPROVEMENT TO VFR EXPECTED THIS AFTERNOON. * NORTH-NORTHEAST WINDS BECOMING EAST-SOUTHEAST THIS AFTERNOON. MDB //DISCUSSION...UPDATED 09Z... CONTINUING TO WATCH BAND OF LIGHT LAKE EFFECT SNOW MOVE SOUTHWARD INTO LAKE COUNTY ILLINOIS. HAVE NOT SEEN MUCH IN THE WAY OF VSBY REDUCTION SO FAR AND EXPECT ANY REDUCTION TO BE SHORT LIVED. CONVERGENCE ALONG THE IL SHORE CONTINUES TO PLAY A BIT OF HAVOC WITH WINDS. SEEING FLUCTUATIONS BETWEEN NORTH AND NORTHEAST WITH SPEEDS UP AROUND 10 KT THOUGH A FEW GUSTS INTO THE 16-20 KT RANGE HAVE OCCURRED. THINK THAT WINDOW FOR GUSTS WILL BE CONFINED TO THE NEXT FEW HOURS BEFORE SPEEDS DIMINISH SLIGHTLY AS HIGH PRESSURE ARRIVES AND CONVERGENCE ALONG THE LAKE WEAKENS. MDB FROM 06Z... MID-LEVEL DISTURBANCE RESPONSIBLE FOR FRIDAYS SNOW IS MOVING ACROSS THE FORECAST AREA AT ISSUANCE TIME...WITH SNOW ALREADY HAVING ENDED RAPIDLY FROM WEST TO EAST ACROSS THE TERMINALS. PATCHY MVFR CEILINGS REMAIN HOWEVER...GENERALLY IN THE 1200-1800 FOOT RANGE ACROSS NORTHERN IL AT 04Z. A PLACES HAVE SCATTERED OUT TO VFR BRIEFLY...BUT LOW LEVEL NORTH/NORTHEAST WINDS OFF THE LAKE AND SOUTHEAST WISCONSIN SHOULD HELP TO MAINTAIN A PREVAILING MVFR CIG THROUGH THE NIGHT. WITH SNOW ASSOCIATED WITH LARGE SCALE SYSTEM MOVING OFF TO THE EAST...RADAR IS NOW ABLE TO BETTER DEPICT WEAK BAND OF LIGHT LAKE EFFECT SNOW WHICH HAS BEEN PERSISTENT ALONG CONVERGENCE ZONE/TROUGH IN LOW LEVEL WINDS. THIS LIGHT SNOW IS CURRENTLY AFFECTING MAINLY FAR SOUTHEAST WI FROM MKE SOUTH TO RAC/ENW...BUT HIGH RES MODELS CONTINUE TO INDICATE THAT THIS WILL SHIFT SOUTH ACROSS LAKE/COOK COUNTIES LATER TONIGHT AND LINGER SATURDAY MORNING BEFORE WINDS SHIFT MORE EAST/SOUTHEAST IN THE AFTERNOON. FORECAST SOUNDINGS DEPICT FAIRLY HEALTHY INVERSION ALOFT WHICH LOOKS TO PREVENT MUCH IN THE WAY OF DEEP LAKE-INDUCED CONVECTION FROM DEVELOPING...BUT A PERIOD OF PESKY LIGHT SNOW/SNOW SHOWERS APPEARS LIKELY DURING THE ROUGHLY 10-15Z PERIOD INTO ORD. ONCE LOW LEVEL FLOW BECOMES MORE EASTERLY/SOUTHEASTERLY SATURDAY AFTERNOON...MVFR CIGS SHOULD CONTINUE TO RISE AND SCATTER...WITH VFR CONDITIONS EXPECTED DURING THE LATE AFTERNOON/EARLY EVENING. MODELS SUGGEST MVFR CIG AROUND 2500 FT MAY DEVELOP LATER SATURDAY EVENING AS WARM ADVECTION DEVELOPS AHEAD OF THE NEXT APPROACHING UPPER TROUGH. RATZER //ORD AND MDW CONFIDENCE...UPDATED 09Z... * MEDIUM-HIGH CONFIDENCE IN MVFR CIG TRENDS THROUGH THE MORNING. * MEDIUM CONFIDENCE IN LAKE EFFECT SNOW SHOWERS...THOUGH LOW CONFIDENCE IN EXACT PLACEMENT OF NARROW BAND AND DETAILS OF RELATED CIG/VIS. * MEDIUM-HIGH CONFIDENCE IN WIND TREND. MDB //OUTLOOK FOR ORD/MDW FOR 12Z SUNDAY-12Z FRIDAY...UPDATED 00Z... SUNDAY...CHANCE OF RAIN OR DRIZZLE. MVFR PROBABLE WITH IFR CEILINGS/VIS. MONDAY...CHANCE OF RAIN OR SNOW. MVFR POSSIBLE. TUESDAY...VFR. WEDNESDAY...CHANCE OF RAIN OR SNOW...OTHERWISE VFR. THURSDAY...SLGT CHANCE OF LGT SNOW...OTHERWISE VFR. RATZER && .MARINE... 252 AM CST HIGH PRESSURE WILL SPREAD ACROSS LAKE MICHIGAN TODAY BUT THE WEAK LARGER SCALE FLOW WILL CONTINUE TO SUPPORT LAKE INFLUENCED WINDS...ESPECIALLY ACROSS THE SOUTHERN PART OF THE LAKE. AN AREA OF CONVERGENCE CONTINUES TO MOVE DOWN THE WESTERN SHORE TOWARD THE IL/WI BORDER WITH NORTHWEST WINDS TO THE WEST AND EAST TO NORTHEAST WINDS TO THE EAST OF THIS BOUNDARY. SPEEDS ARE GENERALLY IN THE 10-20 KT RANGE WITH A FEW GUSTS TO 25 KT POSSIBLE BUT SHOULD FALL OFF AS THE CONVERGENCE WEAKENS THROUGH LATE MORNING/EARLY AFTERNOON. OTHERWISE WINDS WILL BECOME VARIABLE ACROSS MUCH OF THE LAKE THIS AFTERNOON AS THE HIGH ARRIVES. WINDS WILL THEN TURN SOUTHERLY INTO THIS EVENING WITH SPEEDS STEADILY PICKING UP FROM SOUTH TO NORTH. IT APPEARS THAT LOW END GALES WILL BE POSSIBLE LATE TONIGHT AND CONTINUE THROUGH MUCH OF SUNDAY. SURFACE LOW PRESSURE NOW BUILDING INTO THE HIGH PLAINS WILL CONSOLIDATE TO THE WEST OR SOUTHWEST AND THEN MOVE NORTH- NORTHEASTWARD UP LAKE MICHIGAN SUNDAY NIGHT AND MONDAY MORNING. THIS MAY RESULT IN A BRIEF EASING OF THE WINDS SUNDAY EVENING BUT THIS TIMING IS SUBJECT TO CHANGE BASED ON THE SPEED OF THE LOW. WINDS WILL THEN SHIFT TO THE SOUTHWEST AND WEST MONDAY WITH GALES RETURNING...ESPECIALLY SOUTH...THAT IS IF SPEEDS EASE BELOW GALES AS THE LOW MOVES OVER THE LAKE. WILL KEEP THE GALE WATCH GOING THROUGH SUNDAY EVENING BUT IT MAY NEED TO BE EXTENDED RIGHT THROUGH MONDAY AND MONDAY NIGHT. HIGH PRESSURE WILL BUILD BACK ACROSS THE LAKE TUESDAY ALLOWING WINDS TO DIMINISH. THE REST OF THE WEEK LOOKS ACTIVE WITH A SERIES OF LOWS EXPECTED TO PASS NORTH OF THE LAKE RESULTING IN PERIODIC WIND SHIFTS AS EACH ASSOCIATED TROUGH AXIS PASSES WITH AN INCREASE IN WINDS SPEED AS THIS OCCURS AS WELL. TOO EARLY TO TELL IF SHORT PERIODS OF GALES WILL MATERIALIZE BUT IT IS A POSSIBILITY. MDB && .LOT WATCHES/WARNINGS/ADVISORIES... IL...NONE. IN...NONE. LM...GALE WATCH...LMZ080-LMZ261-LMZ362-LMZ364-LMZ366-LMZ563-LMZ565- LMZ567-LMZ669-LMZ671-LMZ673-LMZ675-LMZ777-LMZ779-LMZ868- LMZ870-LMZ872-LMZ874-LMZ876-LMZ878...3 AM SUNDAY TO 9 PM SUNDAY. && $$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
1048 PM CST FRI JAN 20 2012 .DISCUSSION... 910 PM CST ALL ILLINOIS COUNTIES ARE CLEARED FROM ANY WINTER HEADLINES...WITH INDIANA TO BE FOLLOWING SUIT SHORTLY. STILL SOME LIGHT SNOW SHOWERS TO FLURRIES PERSIST FROM ROUGHLY THE I-57 CORRIDOR AND EAST... BUT OVERALL TRENDS CONTINUE TO DECREASE...AND QUICKLY. FOCUS ON THE OVERNIGHT WILL THEN TURN TO THE POTENTIAL FOR LAKE EFFECT SNOWS WITH A CONVERGENT BOUNDARY THAT IS NOTED ON TMKE FROM EAST OF MILWAUKEE...SOUTHWEST TO ROUGHLY KRAC. HIGH RESOLUTION GUIDANCE HAS BEEN CONSISTENT IN TAKING THE BOUNDARY AND SWINGING IT SOUTH...IMPACTING THE COASTAL CITIES. 850 TO LAKE SURFACE DELTA T/S LOOK SUPPORTIVE FOR A SHORT TIME...AND ALL GUIDANCE KEEPS THE PRESENT CONVERGENT BOUNDARY AND SUBSEQUENT LES PRESENT INTO THE AFTERNOON. NO REAL CHANGE TO THE THINKING FROM DAY SHIFT AND WILL ONLY MAINTAIN THE SLIGHT CHANCE POPS FOR COASTAL LOCATIONS. NOT EXPECTING MUCH ADDITIONAL SNOWFALL WITH THESE SHOWERS...AND AMOUNTS LESS THAN AN INCH. SHEA //PREV DISCUSSION... 655 PM CST THE HEAVIEST OF SNOWFALL IS BEGINNING TO SHIFT EAST OF THE AREA WITH MOST LOCATIONS AT OR ABOVE 1/2 TO 1 MILE VIS. THE EARLIER HEAVY BANDING LINED UP NICELY WITH AN AREA OF RUC ANALYZED FGEN WITHIN THE H85 TO H7 LAYER. THAT AREA WILL CONTINUE TO WEAKEN AND SHIFT EAST - AND NOT EXPECTING ANY FURTHER SIGNIFICANT REDUCTIONS TO VIS OR INCH PER HOUR SNOWFALL THOUGH THE EVENING. THE BACK EDGE OF THE PRECIP IS NOTED BASICALLY NOTED FROM WHITEWATER WISCONSIN...SOUTHWEST THROUGH FREEPORT ILLINOIS. PRESENT WSW GOES THROUGH 03Z FOR THE NORTHWESTERN TIER OF COUNTIES...AND MAY BEGIN TO PULL COUNTIES EARLIER AS THE BACK EDGE MOVES THROUGH. FOR COUNTIES EAST...STILL EXPECT THE SNOWFALL TO DECREASE THROUGH THE EVENING WITH ONLY MINOR ACCUMULATIONS FOR AREAS WEST OTHE 355/57 CORRIDOR...AND ANOTHER INCH OR SO FOR LOCATIONS ALONG THE ILLINOIS/INDIANA BORDER AND EAST. SHEA .PREVIOUS DISCUSSION... 344 PM CST NO MAJOR SURPRISES SO FAR...DID EXPAND THE WINTER STORM WARNING INTO LEE COUNTY THIS AFTERNOON WHICH HAS SEEN PROLONGED PERIOD OF HEAVIER SNOWFALL WITH DECENT RETURNS STILL UPSTREAM. KENDALL AND WILL COUNTIES WILL BE CLOSE TO WARNING CRITERIA OF 6" AS AXIS OF MAXIMUM SNOW SETS UP PRETTY MUCH AS EXPECTED BETWEEN THE I-90 AND I-80 CORRIDORS WITH RATES OF AN INCH AN HOUR...OCCASIONALLY 1.5 INCHES PER HOUR. EXPECT INTENSITIES TO PEAK ACROSS THE CHICAGO METRO AREA THROUGH THE EARLY EVENING. DID GET OFF TO A SLOWER START THAN EXPECTED AND SNOW:LIQUID RATIOS HAVE BEEN A BIT LOWER THAN ORIGINALLY ANTICIPATED...SO FOR NOW BELIEVE DESPITE THE AXIS SETTING UP FARTHER SOUTH THAN THE ORIGINAL WARNING AREA...THAT ADVISORY FOR 4 TO 6 INCHES ACROSS KENDALL/WILL COUNTIES AND LAKE COUNTY INDIANA WILL STAND //THOUGH MAY SEE SOME LOCALIZED AREAS AT OR JUST ABOVE 6 INCHES PARTICULARLY ACROSS FAR NORTHERN WILL COUNTY//. WIDESPREAD VSBY OF 1/4 MILE OR LESS HAS BEEN REPORTED AND INTERMITTENT PERIODS OF HEAVY SNOW CONTINUE SO ROADWAYS WILL BE A MESS THROUGH THE EVENING HOURS. SATURDAY THROUGH FRIDAY... SHORT TERM...SATURDAY THROUGH MONDAY...FOLLOWING THE PASSAGE OF THE MID LEVEL SYSTEM RESPONSIBLE FOR THE SYNOPTIC SNOW...THE INITIAL FORECAST CONCERN WILL FOCUS ON THE POTENTIAL FOR A LAKE EFFECT BAND OF SNOW MOVING INTO NERN IL. ALL OF THE GUIDANCE IS INDICATING LAKE SFC-850MB DELTA-T AROUND 15C OVER SOUTHERN LAKE MICHIGAN...WHICH WOULD BE CONDUCIVE TO LAKE EFFECT SNOW DEVELOPMENT. THE HIGH RES WRF-ARW/NMM WITH SUPPORT OF THE OPERATIONAL NAM12...ALL INDICATE A CONVERGENCE BAND FORMING OVER SOUTHERN LAKE MICHIGAN...WITH THE POSSIBILITY OF MESOVORTEX DEVELOPMENT WITHIN THE CONVERGENCE ZONE AND INVERTED TROUGH. WITH TIME...THE BAND SHOULD GRADUALLY MOVE INLAND AND TO THE NORTHWEST...POSSIBLE AFFECTING PORTIONS OF NERN AND NCNTRL IL. CONCURRENTLY...LAKE SFC-850MB DELTA T VALUES WILL BE ON THE DECREASE. SO...EXPECT MORE OF AN ADVECTING BAND OF LAKE EFFECT SNOW THAN CONTINUOUS PRODUCTION OF LAKE EFFECT SNOW OVER THE IMMEDIATE LAKE FRONT LOCATIONS. AT THIS TIME...HAVE OPTED TO DEPICT THIS LAKE EFFECT BAND IN THE GRIDDED FORECAST GRAPHICS WITH AN AREA OF CHANCE TO SLIGHT CHANCE POPS WITH -SHSN. THERE IS CERTAINLY THE POTENTIAL FOR ADDITIONAL ACCUMULATING SNOW WITH THE MAIN CONVERGENCE AREA...BUT DUE TO THE MESOSCALE NATURE OF ANY POSSIBLE MESOVORTEX DEVELOPMENT...IT IS NOT POSSIBLE TO PINPOINT ANY POSSIBLE HEAVIER LAKE EFFECT SNOW WITH THIS FEATURE...WHICH WOULD NEED TO BE HANDLED WITH A NEAR TERM FORECAST UPDATE TOMORROW. ON A LARGER SCALE...HIGH PRESSURE SHOULD BUILD OVER THE AREA BRINGING DECREASING CLOUD COVER. TO START OUT SATURDAY MORNING...TEMPERATURES SHOULD RANGE FROM THE LOWER SINGLE DIGITS OVER THE NWRN PORTIONS OF THE CWA...WHERE SKIES SHOULD CLEAR THE EARLIEST AND THE GREATEST AMOUNT OF RADIATING SHOULD OCCUR...TO THE UPPER TEENS ALONG THE LAKE FRONT...WHERE THERE SHOULD BE THE GREATEST AMOUNT OF RESIDUAL CLOUD COVER. WITH AT LEAST PARTIAL SUNSHINE AND AN END TO SUSTAINED COLD ADVECTION OVER THE AREA ON SATURDAY...TEMPERATURES SHOULD SHOULD REBOUND INTO THE LOWER TO MIDDLE 20S. BY SUNDAY...THE HIGH WILL MOVE OFF TO THE EAST. A MORE COMPLICATED SITUATION WILL BE SETTING UP TO THE WEST OF THE LOCAL AREA BY SUNDAY. STRONG NORTHERN AND SOUTHERN STREAM SHORTWAVES ARE EXPECTED TO EJECT OUT OF THE ROCKIES BY SUNDAY MORNING...WITH A LARGE AREA OF LOW PRESSURE DEVELOPING OVER THE CENTRAL PLAINS. THIS WILL INITIATE STRONG WARM/MOIST ADVECTION INTO THE MIDWEST. THE MODELS ARE INDICATING PHASING OF THE NORTHERN AND SOUTHERN STREAMS...WITH A CONSOLIDATED SFC LOW FORMING OVER LOWER MICHIGAN BY MONDAY MORNING. THE MAIN CHANGE TO THE GOING FORECAST WITH RESPECT TO THIS SYSTEM IS TO SPEED UP THE PROGRESSION WITH A COLD FRONTAL PASSAGE LATE SUNDAY NIGHT OR EARLY MONDAY MORNING. WITH THE STRONG WARM ADVECTION...ASSOCIATED PCPN WILL START OUT IN LIQUID FORM AS TEMPERATURES CLIMB INTO THE UPPER 30S TO LOWER 40S THROUGH THE DAY...WITH TEMPERATURES REMAINING NEARLY STEADY INTO THE NIGHT. TEMPERATURES WILL NOT DROP OFF UNTIL AFTER THE FROPA...WHEN TEMPERATURES WILL DROP INTO THE LOWER 20S OVER THE ROCKFORD AREA. FARTHER SOUTHEAST...SOUTH OF THE KANKAKEE VALLEY...TEMPS WILL ONLY DROP INTO THE MIDDLE 30S SO A CHANGEOVER FROM RAIN TO SNOW MAY NOT OCCUR UNTIL LATE IN THE DAY. IT IS EVEN POSSIBLE THAT TEMPS OVER BENTON/JASPER/NEWTON COUNTY AREA MAY NOT COOL OFF ENOUGH BEFORE THE SYSTEM LIFTS OUT LATE MONDAY TO EVER SEE ANY ADDITIONAL SNOW. EXTENDED FORECAST...TUESDAY THROUGH FRIDAY...CONDITIONS SHOULD QUIET DOWN CONSIDERABLY THROUGH THE EXTENDED FORECAST PERIOD. BY TUESDAY...HIGH PRESSURE WILL ONCE AGAIN DOMINATE THE REGION. A SPLIT FLOW PATTERN IS EXPECTED TO DEVELOP WITH AN ACTIVE NORTHERN STREAM FOCUSED ALONG THE CANADIAN BORDER WHILE AN ACTIVE SOUTH STREAM WILL BE FOCUSED ALONG THE RED RIVER VALLEY AND OHIO VALLEY. IN BETWEEN THESE TWO STREAMS...THE MIDDLE MISSISSIPPI VALLEY AND MIDWEST WILL REMAIN UNDER A WEAK RIDGE OF HIGH PRESSURE. THE BEST CHANCE FOR ANY PCPN BETWEEN EARLY TUESDAY AND EARLY FRIDAY WILL BE ON WEDNESDAY WHEN THE NRN STREAM SYSTEM WILL BE PASSING THROUGH THE UPPER GREAT LAKES AND STRONG WARM ADVECTION DEVELOPS OVER THE LOWER AND MIDDLE MISSISSIPPI VALLEY AND SPREADING INTO SOUTHERN IL/IN. BETWEEN THESE TWO SYSTEM...THERE IS A CHANCE FOR SOME LIGHT RAIN OVER THE SOUTHERN PORTIONS OF THE CWA...WITH SOME LIGHT SNOW POSSIBLE OVER THE NRN LOCATIONS. THERE MAY BE A BRIEF TRANSITION OVER TO ALL LIGHT SNOW WEDNESDAY NIGHT...BEFORE THE NRN STREAM SYSTEM SCOOTS OFF TO THE EAST. THE NEXT SIGNIFICANT CHANCE FOR PCPN WILL NOT BE UNTIL LATE IN THE EXTENDED PERIOD...AND WILL BE ASSOCIATED WITH THE SRN STREAM SYSTEM. THE GFS AND ECMWF ARE IN DECENT ENOUGH AGREEMENT ON THIS SYSTEM...THOUGH THE ECMWF IS A BIT FASTER AND HAS A GREATER DEGREE OF PHASING WITH THE NRN STREAM THAN THE GFS...WHICH INDICATES MORE OF A CUT OFF LOW AND...CONSEQUENTLY... IS MORE SLOWLY PROGRESSIVE. DEPENDING ON WHETHER THE FASTER OR THE SLOW SOLUTION VERIFIES...WE COULD SEE PCPN MOVING BACK INTO THE AREA AS EARLY AS THURSDAY PER THE ECMWF OR FRIDAY PER THE GFS. AT THIS POINT...HAVE GONE WITH A MORE MIDDLE OF THE ROAD APPROACH FOR THE LATE EXTENDED PERIOD POPS...WITH SLIGHT CHANCE POPS FOR THURSDAY NIGHT AND CHANCE POPS FOR FRIDAY. KREIN && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 06Z... * MVFR CIGS LINGERING OVERNIGHT AND SATURDAY MORNING. * POTENTIAL FOR LIGHT LAKE EFFECT SNOW SHOWERS TOWARD MORNING. * IMPROVEMENT TO VFR EXPECTED SATURDAY AFTERNOON. * NORTH-NORTHEAST WINDS BECOMING EAST-SOUTHEAST SATURDAY AFTERNOON. RATZER //DISCUSSION...UPDATED 06Z... MID-LEVEL DISTURBANCE RESPONSIBLE FOR FRIDAYS SNOW IS MOVING ACROSS THE FORECAST AREA AT ISSUANCE TIME...WITH SNOW ALREADY HAVING ENDED RAPIDLY FROM WEST TO EAST ACROSS THE TERMINALS. PATCHY MVFR CEILINGS REMAIN HOWEVER...GENERALLY IN THE 1200-1800 FOOT RANGE ACROSS NORTHERN IL AT 04Z. A PLACES HAVE SCATTERED OUT TO VFR BRIEFLY...BUT LOW LEVEL NORTH/NORTHEAST WINDS OFF THE LAKE AND SOUTHEAST WISCONSIN SHOULD HELP TO MAINTAIN A PREVAILING MVFR CIG THROUGH THE NIGHT. WITH SNOW ASSOCIATED WITH LARGE SCALE SYSTEM MOVING OFF TO THE EAST...RADAR IS NOW ABLE TO BETTER DEPICT WEAK BAND OF LIGHT LAKE EFFECT SNOW WHICH HAS BEEN PERSISTENT ALONG CONVERGENCE ZONE/TROUGH IN LOW LEVEL WINDS. THIS LIGHT SNOW IS CURRENTLY AFFECTING MAINLY FAR SOUTHEAST WI FROM MKE SOUTH TO RAC/ENW...BUT HIGH RES MODELS CONTINUE TO INDICATE THAT THIS WILL SHIFT SOUTH ACROSS LAKE/COOK COUNTIES LATER TONIGHT AND LINGER SATURDAY MORNING BEFORE WINDS SHIFT MORE EAST/SOUTHEAST IN THE AFTERNOON. FORECAST SOUNDINGS DEPICT FAIRLY HEALTHY INVERSION ALOFT WHICH LOOKS TO PREVENT MUCH IN THE WAY OF DEEP LAKE-INDUCED CONVECTION FROM DEVELOPING...BUT A PERIOD OF PESKY LIGHT SNOW/SNOW SHOWERS APPEARS LIKELY DURING THE ROUGHLY 10-15Z PERIOD INTO ORD. ONCE LOW LEVEL FLOW BECOMES MORE EASTERLY/SOUTHEASTERLY SATURDAY AFTERNOON...MVFR CIGS SHOULD CONTINUE TO RISE AND SCATTER...WITH VFR CONDITIONS EXPECTED DURING THE LATE AFTERNOON/EARLY EVENING. MODELS SUGGEST MVFR CIG AROUND 2500 FT MAY DEVELOP LATER SATURDAY EVENING AS WARM ADVECTION DEVELOPS AHEAD OF THE NEXT APPROACHING UPPER TROUGH. RATZER //ORD AND MDW CONFIDENCE...UPDATED 06Z... * MEDIUM-HIGH CONFIDENCE IN MVFR CIG TRENDS THROUGH SATURDAY MORNING. * MEDIUM CONFIDENCE IN LAKE EFFECT SNOW SHOWERS...THOUGH LOW CONFIDENCE IN EXACT PLACEMENT OF NARROW BAND AND DETAILS OF RELATED CIG/VIS. * MEDIUM-HIGH CONFIDENCE IN WIND TREND. RATZER //OUTLOOK FOR ORD/MDW FOR 12Z SUNDAY-12Z FRIDAY...UPDATED 00Z... SUNDAY...CHANCE OF RAIN OR DRIZZLE. MVFR PROBABLE WITH IFR CEILINGS/VIS. MONDAY...CHANCE OF RAIN OR SNOW. MVFR POSSIBLE. TUESDAY...VFR. WEDNESDAY...CHANCE OF RAIN OR SNOW...OTHERWISE VFR. THURSDAY...SLGT CHANCE OF LGT SNOW...OTHERWISE VFR. RATZER && .MARINE... 316 PM CST TWO LOW PRESSURE SYSTEMS...ONE OVER ONTARIO AND ONE IN THE OHIO VALLEY...WILL FIGHT FOR INFLUENCE OVER THE LAKE THIS EVENING. THIS WILL RESULT IN VARIABLE WINDS FOR A WHILE...WHICH EVENTUALLY TURN NORTHWEST OVER THE NORTH HALF AND NORTHEAST OVER THE SOUTH AHEAD OF AN APPROACHING CENTER OF HIGH PRESSURE. WINDS GO LIGHT AND VARIABLE AS THE HIGH PRESSURE MOVES ACROSS THE LAKE TOMORROW. BY SUNDAY A NEW LOW PRESSURE SYSTEM AND TRAILING COLD FRONT APPROACH FROM THE WEST. DECISION TO POST A GALE WATCH FOR SUNDAY WAS BASED ON EXPECTATION OF STRONG SOUTH WINDS AHEAD OF THE FRONT...GUSTING INTO THE 35 KT RANGE. ACTUALLY FEEL STRONGER WINDS WILL ARRIVE MONDAY AFTER THE FRONT PASSES AND WINDS TURN WEST. THESE ALSO WILL HAVE THE ADVANTAGE OF BEING COLDER AND IN A MORE WELL MIXED AIRMASS...THUS SUPPORTING BETTER MIXING OF GUSTS TO THE LAKE SURFACE. AT THIS POINT THE REST OF NEXT WEEK LOOKS RELATIVELY QUIET...FOR NOW. LENNING && .LOT WATCHES/WARNINGS/ADVISORIES... IL...NONE. IN...NONE. LM...GALE WATCH...LMZ080-LMZ261-LMZ362-LMZ364-LMZ366-LMZ563-LMZ565- LMZ567-LMZ669-LMZ671-LMZ673-LMZ675-LMZ777-LMZ779-LMZ868- LMZ870-LMZ872-LMZ874-LMZ876-LMZ878...3 AM SUNDAY TO 9 PM SUNDAY. && $$
AREA FORECAST DISCUSSION
NWS NORTHERN INDIANA
1228 AM EST SAT JAN 21 2012 .AVIATION... BACK EDGE OF AREA OF SNOW MOVG EAST ACROSS NRN INDIANA ATTM AND SHOULD CLEAR FWA IN NEXT COUPLE OF HOURS WITH VFR CONDITIONS UPSTREAM OVER SW MI/NW INDIANA FOLLOWING THE END OF THE SNOW OVERNIGHT. VFR CONDITIONS SHOULD PERSIST DURING THE DAY AND INTO TONIGHT AS HIGH PRESSURE RIDGE MOVES ACROSS THE AREA. && .PREV DISCUSSION... UPDATE... SNOW EVENT EVOLVING AS EXPECTED SO FAR. UPSTREAM REPORTS IN NORTHERN IL INDICATE EXPECTED POTENTIAL FOR SOME AMOUNTS NEAR OR JUST ABOVE 6 INCHES. CURRENT ADVISORY HAS THIS WELL IN HAND WITH WORDING SO CURRENTLY NO PLANS TO UPGRADE HEADLINES UNLESS WE START GETTING WIDESPREAD REPORTS IN EXCESS OF 6 TO 7 INCHES LATER THIS EVENING WITH ADDITIONAL SNOWFALL EXPECTED. MOST REPORTS SO FAR IN THE 1 TO 3 INCH RANGE WITH A FEW EXCEPTIONS. VISIBILITIES BEGINNING TO RISE SLOWLY NEAR AND WEST OF CHICAGO SO EXPECT OUR WESTERN AREAS TO SEE THIS MODERATE TO BRIEFLY HEAVY SNOW FOR A FEW MORE HOURS BEFORE SNOWFALL RATES GRADUALLY DECREASE THERE WITH PROGRESSION EAST THROUGH THE LATE EVENING AND OVERNIGHT HOURS. HIGH RES GUIDANCE ALSO SHOWING THIS WITH HRRR LOOKING VERY GOOD SO FAR. SHORT TERM...TONIGHT THROUGH SATURDAY NIGHT MAIN FORECAST FOCUS WILL CONTINUE TO CENTER ON SIGNIFICANT SNOW ACCUMULATIONS TONIGHT. A WINTER WEATHER ADVISORY WILL REMAIN IN EFFECT FOR THE ENTIRE FORECAST AREA THROUGH 12Z SATURDAY. A ZONE OF STRONG ISENTROPIC UPGLIDE PER RUC/GFS 290K SFC WILL CONTINUE TO LIFT NORTHEAST ACROSS NORTHERN PORTIONS OF THE FORECAST AREA. SEVERAL REPORTS NOW OF 1/2 TO 1/4 MILE VSBYS ACROSS NORTHERN ILLINOIS AND STRONGEST ISENTROPIC ASCENT SHOULD SHIFT EASTWARD ACROSS NORTHERN INDIANA/SOUTHERN LOWER MICHIGAN IN THE 22Z-03Z TIMEFRAME. DURING THIS PERIOD OF STRONGER FORCING...STRONGEST UPWARD VERTICAL MOTION SHOULD BE SOLIDLY ENCOMPASSED IN FAVORABLE DENDRITIC GROWTH ZONE. THUS...SHOULD SEE A PERIOD EARLY THIS EVENING WHERE SNOW TO LIQUID RATIOS INCREASE SHARPLY FOR A TIME. ISENTROPIC PROGS HAVE ALSO SUGGESTED PERHAPS A SLIGHT WEAKENING OF THE ISENTROPIC LIFT THIS EVENING AS VORT MAX SKIRTING ACROSS SOUTHERN WISCONSIN THIS AFTERNOON BECOMES MORE SHEARED ACROSS THE SOUTHERN LAKES. NONETHELESS...A 2 TO 4 PERIOD OF SNOWFALL RATES AROUND AN INCH PER HOUR APPEARS TO BE POSSIBLE LATE THIS AFTERNOON/EARLY THIS EVENING FOR AREAS ESPECIALLY ALONG AND NORTH OF THE ROUTE 30 CORRIDOR. ACCUMULATIONS WILL BE IN SOMEWHAT MORE QUESTION ACROSS THE SOUTH AS THIS BAND SHOULD PROVIDE GREAT IMPACTS ACROSS THE NORTHERN HALF. WATER VAPOR IMAGERY CONTINUES TO INDICATE A STRONGER VORT MAX DROPPING INTO THE CENTRAL PLAINS THAT WILL BEGIN TO SHIFT EASTWARD INTO THE MID MS RVR VALLEY LATER THIS EVENING. SHOULD START TO SEE A MORE FRONTALLY FORCED AREA OF SNOW DEVELOP EXTENDING SOUTHWEST FROM THIS INITIALLY WEST TO EAST ORIENTED BAND THAT WILL AFFECT CENTRAL/SOUTHERN AREAS LATE THIS EVENING. STILL EXPECTING STORM TOTAL SNOWFALL AMOUNTS IN THE 4 TO 7 RANGE CENTRAL AND NORTH...WITH AMOUNTS IN THE 2 TO 4 RANGE FAR SOUTH. GFS/RUC VERTICAL CROSS SECTIONS ALSO INDICATE INCREASING INSTABILITY ALOFT (NEGATIVE EPV) LIFTING ACROSS EASTERN SECTIONS OF THE AREA LATE THIS EVENING AS SOUTHWESTERLY FLOW STRENGTHENS IN ADVANCE OF THIS SECONDARY SHORT WAVE. THIS INCREASE IN INSTABILITY ALOFT SHOULD CORRESPOND TO THIS SECONDARY MID LEVEL FORCING MAX WITH THIS SHORT WAVE...SO HAVE KEPT AMOUNTS MORE SOLIDLY IN THE ADVISORY RANGE IN THE FAR SOUTHEAST...WITH SLIGHTLY LESSER TOTALS IN THE SOUTHWEST. CURRENTLY HAVE DRAWN UP TOTAL ACCUMULATIONS JUST BELOW ADVISORY CRITERIA ACROSS THE SOUTHWEST BUT DUE TO COMPLICATING MESOSCALE FORCING MECHANISMS MENTIONED...WILL MAINTAIN ALL HEADLINES AT THIS TIME. CONDITIONS TO IMPROVE FROM WEST TO EAST OVERNIGHT WITH THE PASSAGE OF THIS SECONDARY VORT MAX. ORIENTATION OF RIDGE AXIS TO THE WEST SHOULD SUPPORT ANY LAKE EFFECT SNOW SHOWERS WEST OF THE LOCAL FORECAST AREA INTO NORTHWEST INDIANA/NORTHEAST ILLINOIS. SATURDAY SHOULD FEATURE QUIET WEATHER WITH SFC HIGH BEGINNING TO BUILD IN. WEAK LOW LEVEL EASTERLIES AND NEW SNOW COVER SHOULD PROMOTE WEAK MIXING AND HAVE UNDERCUT MOST AVAILABLE GUIDANCE FOR HIGH TEMPS. LONG TERM... SUNDAY THROUGH FRIDAY MID LEVEL FLOW TRANSITION STILL ON TRACK IN THE PERIOD GIVEN THE RETURN OF ALASKA TROUGHING...WITH MUCH MILDER PAC ORIGIN DOWNSLOPE FLOW EXPECTED INTO THE REGION BY EARLY NEXT WEEK. A DEEP LONGWAVE TROUGH IS STILL EXPECTED IN THE SUN NIGHT-MON PERIOD...SUPPORTING ROBUST LL FLOW FIELDS WITH SIG THETA-E ADVECTION INTO THE AREA. SPLIT FLOW REGIME WILL FOLLOW WITH STRONG MODEL/ENSEMBLE SUPPORT CONTINUING. FAST PERTURBED WNW FLOW WILL OFFER LOW CONFIDENCE PER DISTURBANCE TIMING IN THE LATE PERIODS GIVEN TYPICAL POOR MODEL PERFORMANCE PER THESE FEATURES. HENCE...NO SIG CHANGE PER PRECIP CHANCE WED-FRI...WITH PREFERENCE TOWARD 24-36 HOUR FORECAST WINDOWS PER PRECIP CHANCES GIVEN INHERENT VARIABILITY PER IMPULSE TIMING. SUN-MON...SIG MID LEVEL TROUGH IS STILL ON TRACK TO DIG INTO THE SW CONUS AND BEGIN TO EJECT TOWARD THE REGION. ECMWF/GEM/UKMET ARE PREFERRED GIVEN THEIR HANDLING OF THE DIGGING MID LEVEL TROUGH WITH NEGATIVE TILT CHARACTERISTICS. CERTAINLY DONT BUY THE NAM/S OUTLIER NORTH BIAS PER THE SFC CYCLONE AND THE GFS/S WILD VARIABILITY PER TROUGH DEPTH/TIMING/AND TRACK. CONTINUED MODEL SUPPORT FOR A STRONG SOUTHERN PERIPHERY UPPER JET STREAK AND NEGATIVE UPPER TROUGH TILT SUGGESTS A WEST BIAS TO THE SFC LOW TRACK WITH SLOWER SYSTEM ARRIVAL AND HAVE CONTINUED THIS IN THE GRIDS. SYSTEM INFLUENCE TO THE LOCAL AREA WILL BEGIN ON SUNDAY...WITH REFLECTED LL SOUTHERLY FLOW INCREASING THROUGH THE SUNDAY DAY PERIOD. LINGERING BAROCLINIC ZONE IN PLACE OVER THE CENTRAL PLAINS WILL INTERACT WITH THE EJECTING MID LEVEL DISTURBANCE TO SUPPORT ROBUST SFC PRESSURE FALLS...SUPPORTING RAPID SFC CYCLOGENESIS. THIS WILL ALLOW SIG LL THETA-E ADV TO ENSUE LATE SUNDAY IN THE REGION WITH SIG SFC LAYER DEWPOINT RISES BY SUNDAY NIGHT. STAUNCH LL FLOW WITH A 60 TO 70 KNOT LLJ PROGGED IN THE ECMWF...WILL BE MORE THAN ENOUGH TO SUPPORT DEEP LAYER THETA-E RISES. SNOWPACK IN PLACE WILL LIKELY SUPPORT A SATURATED BL WITH DRIZZLE AND FOG EXPECTED TO DEVELOP LATE SUNDAY AFTERNOON /AT THE EARLIEST/ INTO THE EVENING...LIKELY PERSISTING THROUGH SUNDAY NIGHT. ECMWF H7-H3 LAYER ANALYSIS CONTINUES TO INDICATE AN INTACT EML WITH STEEP MID LEVEL LAPSE RATES GIVEN STRONG LOW CENTERED WAA. H85 THETA-E APPROACHES 325K BY LATE SUNDAY NIGHT...WITH SW INDICES NEGATIVE...INDICATING A GOOD ENVIRONMENT FOR ELEVATED THUNDERSTORMS. HAVE MAINTAINED A LOW CHANCE THUNDER AT THIS POINT. ALBEIT SMALL...THERE REMAINS A SMALL CONCERN FOR SEVERE WEATHER GIVEN INDICATED H5 JETLET IN EXCESS OF 85 KNOTS...WHICH WOULD BE CAPABLE OF SUPPORTING A QLCS JET DRIVEN THIN LINE. CONCERNS FOR INCREASED FLOODING CONTINUE GIVEN FULL SNOWPACK MELT WITH THE POTENTIAL FOR HEAVY RAIN. IN ADDITION...A SLOWER TROUGH ARRIVAL PER NEGATIVE TROUGH TENDENCIES WOULD SUPPORT HIGHS INTO THE 50S AKIN TO ECMWF PROGS. CAA WILL DOMINATE MONDAY WITH FALLING TEMPS IN THE DAYTIME PERIOD LIKELY. LINGERING LIGHT SNOW SHOWERS WILL BE POSSIBLE. TUE-FRI...FAST WNW PAC ORIGIN FLOW IS EXPECTED INTO THE REGION WITH ROCKIES ENHANCED IMPULSES EXPECTED. STRONGEST PROGGED IMPULSE REMAINS IN THE WED-THUR PERIOD AND HAVE RETAINED POPS THEN...OPTING TO KEEP THE RAIN/SNOW WORDING GIVEN WARM THERMAL FIELDS. HAVE ALSO EXTENDED THIS MENTION INTO FRIDAY MAINLY PER COLLAB WITH SURROUNDING OFFICES...WHICH ALSO FITS THE ACTIVE PATTERN. OTHERWISE...ADJUSTED TEMPS UP SOME...WITH ABOVE NORMAL TEMPS LIKELY ONCE AGAIN. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...WINTER WEATHER ADVISORY UNTIL 7 AM EST /6 AM CST/ THIS MORNING FOR INZ003>009-012>018-020-022>027-032>034. MI...WINTER WEATHER ADVISORY UNTIL 7 AM EST THIS MORNING FOR MIZ077>081. OH...WINTER WEATHER ADVISORY UNTIL 7 AM EST THIS MORNING FOR OHZ001- 002-004-005-015-016-024-025. LM...NONE. && $$ SHORT TERM...MARSILI LONG TERM...JC AVIATION...JT UPDATE...LASHLEY
AREA FORECAST DISCUSSION
NWS TOPEKA KS
321 AM CST SAT JAN 21 2012 .DISCUSSION... WEAK UPPER TROF WAS EXITING EASTERN KANSAS EARLY THIS MORNING WHILE MUCH STRONGER WAVE WAS APPROACHING THE WEST COAST PER WATER VAPOR IMAGERY. SURFACE RIDGE AXIS REMAINS ACROSS CENTRAL KANSAS..WITH WIDESPREAD STRATUS OOZING SOUTHWEST JUST AHEAD OF IT INTO EAST CENTRAL KANSAS...AND MORE SCATTERED LOW CLOUD TO ITS NORTHWEST IN NORTH CENTRAL KANSAS AND EASTERN NEBRASKA. STRONG PRESSURE FALLS WERE OCCURRING IN THE NORTHERN HIGH PLAINS UNDER QUICK ZONAL FLOW ALOFT. LATEST RUC SEEMS TO BE DOING FAIRLY WELL WITH LOW CLOUD TRENDS...AND SEEMS REASONABLE WITH STRATUS CONTINUING SOUTHWEST THROUGH EAST CENTRAL KANSAS...BUT MAKING LITTLE PROGRESS ELSEWHERE. SHOULD SEE MOSTLY CLEAR SKIES TAKE HOLD BY LATE MORNING. SOUTH WINDS WILL DEVELOP THIS AFTERNOON AS THE RIDGE PUSHES EAST WITH TEMPERATURES RISING TO AROUND FREEZING. LITTLE IN THE WAY OF DIURNAL TEMP FALLS EXPECTED TONIGHT WITH TIGHT PRESSURE GRADIENT DEVELOPING IN EASTERN KANSAS UNDER 30-50KT SOUTH 925MB WINDS. MODEST LOW LEVEL MOISTURE SHOULD RESULT IN STRATUS INTRUSION IN AT LEAST EASTERN AREAS. MAIN FOCUS FOR THE EARLY PERIODS IS STILL THE UPPER TROFS SPEED AND STRENGTH AS IT PASSES THROUGH THE PLAINS SUNDAY AND SUNDAY NIGHT. SIMILAR TO RUNS OF THURSDAY NIGHT...THE NAM IS ON THE QUICK SIDE...ECMWF ON THE SLOW SIDE...AND OTHERS IN BETWEEN. HAVE SIDED CLOSEST TO THE LARGER DOMAIN MODELS THINKING THEY SHOULD HAVE THE BEST HANDLE ON THIS OFF-SHORE SYSTEM...SPECIFICALLY CLOSEST TO THE ECMWF AND GEM. THIS DELAYS THE BEST PRECIPITATION CHANCES TO LATE SUNDAY AFTERNOON AND INTO SUNDAY EVENING. 850MB TEMPS RISE INTO THE 10-12C RANGE TONIGHT...AND DESPITE STRONG AND DEEP COLD AIR ADVECTION WITH THIS SYSTEM...CHANGEOVER TO AN ALL SNOW TYPE SHOULD BE DELAYED UNTIL SUNDAY EVENING. PRECIP WILL LIKELY COINCIDE WITH STRONG NORTHWEST WINDS BEHIND THE PACIFIC FRONT...BUT PRECIP RATES/AMOUNTS AND SPEEDS SHOULD BE LOW ENOUGH TO PRECLUDE ANY HEADLINES. DEEPER MIXING BEHIND THE SYSTEM MONDAY SHOULD PUSH HIGHS BACK INTO THE 40S. TREND FOR THE TUESDAY INTO WEDNESDAY PERIODS CONTINUES TO BE FOR BULK OF ENERGY WITH THE NEXT SHORTWAVE TO DIVE SOUTHEAST...WITH LITTLE FORCING FOR PRECIPITATION THIS FAR NORTH. THERE REMAINS SOME SIGNAL FOR LIGHT AND SPOTTY ACCUMS TO OCCUR...AND SOME MENTION WILL REMAIN FOR TUESDAY AFTERNOON IN THE WEST AND AREA-WIDE TUESDAY NIGHT. TEMPERATURE PROFILES SHOULD SUPPORT RAIN-SNOW AGAIN. ZONAL FLOW SHOULD MAINTAIN ITSELF NORTH OF THE UPPER LOW WITH SOMEWHAT ABOVE NORMAL TEMPS RESULTING. 65 && .AVIATION... SATELLITE SHOWS AREA OF STRATUS OVER SOUTHWESTERN IA MAKING STEADY PROGRESS TO THE SOUTH. THE LATEST RUC AND NAM DO NOT HAVE THE GREATEST HANDEL ON THIS IN THEIR RH PROGS. SO THINK BASED ON ADVECTION ONLY THAT THE STRATUS WILL MAKE A RUN AT TOP AND FOE. AM A LITTLE CONCERNED WITH THE 925 WINDS PROGGED TO VEER TO THE EAST THAT THE STRATUS MAY BE STUBBORN TO MIX OUT UNTIL THE SFC RIDGE AXIS PASSES TO THE EAST. INITIALLY THE CIGS MAY COME IN AT 2500 FT BUT BASED ON OBS UPSTREAM THINK THIS WILL BE TEMPORARY WITH CIGS LIFTING TO 3 KFT OR BETTER. DO NOT HAVE ENOUGH CONFIDENCE IN THEM MAKING IT TO MHK TO INCLUDE IT THERE AT THIS TIME. THE SFC RIDGE AXIS SHOULD PASS TO THE EAST AROUND 18Z WITH VFR CONDITIONS EXPECTED TO PERSIST AND A SOUTHEASTERLY WIND FRESHENING. WOLTERS && .TOP WATCHES/WARNINGS/ADVISORIES... NONE. && $$
AREA FORECAST DISCUSSION
NWS TOPEKA KS
1052 PM CST FRI JAN 20 2012 ...AVIATION UPDATE... .DISCUSSION... SEE PREV DISCUSSION. && .AVIATION... SATELLITE SHOWS AREA OF STRATUS OVER SOUTHWESTERN IA MAKING STEADY PROGRESS TO THE SOUTH. THE LATEST RUC AND NAM DO NOT HAVE THE GREATEST HANDEL ON THIS IN THEIR RH PROGS. SO THINK BASED ON ADVECTION ONLY THAT THE STRATUS WILL MAKE A RUN AT TOP AND FOE. AM A LITTLE CONCERNED WITH THE 925 WINDS PROGGED TO VEER TO THE EAST THAT THE STRATUS MAY BE STUBBORN TO MIX OUT UNTIL THE SFC RIDGE AXIS PASSES TO THE EAST. INITIALLY THE CIGS MAY COME IN AT 2500 FT BUT BASED ON OBS UPSTREAM THINK THIS WILL BE TEMPORARY WITH CIGS LIFTING TO 3 KFT OR BETTER. DO NOT HAVE ENOUGH CONFIDENCE IN THEM MAKING IT TO MHK TO INCLUDE IT THERE AT THIS TIME. THE SFC RIDGE AXIS SHOULD PASS TO THE EAST AROUND 18Z WITH VFR CONDITIONS EXPECTED TO PERSIST AND A SOUTHEASTERLY WIND FRESHENING. WOLTERS && .PREV DISCUSSION... /330 PM CST FRI JAN 20 2012/ THROUGH SATURDAY...AN UPPER LEVEL DISTURBANCE WAS CROSSING THE NORTHERN PLAINS INTO THE GREAT LAKES REGION THIS AFTERNOON WITH SNOW WELL NORTH OF THE FORECAST AREA. SURFACE LOW PRESSURE WAS SITUATED IN THE RED RIVER VALLEY WITH BROAD ISENTROPIC UPSLOPE FLOW PRODUCING A LOW STRATUS CLOUD DECK FROM NORTHEAST OKLAHOMA INTO EASTERN KANSAS AND POINTS EAST. THESE LOW CLOUDS COMBINED WITH WIDESPREAD HIGH CLOUDS... SURFACE COLD ADVECTION AND SNOW COVER IN PARTS OF THE AREA TO KEEP HIGH TEMPS IN THE UPPER 20S AND LOWER 30S TODAY. HIGH PRESSURE WILL BUILD IN TO NORTHERN KANSAS BY MORNING WITH WINDS DECREASING FROM NORTHWEST TO SOUTHEAST AFTER MIDNIGHT. SKIES WILL ALSO CLEAR OUT AND TEMPERATURES WILL FALL QUICKLY AS SOON AS THE WINDS DIMINISH. EXPECT THE COLDEST TEMPS TO BE IN AREAS WITH SNOW COVER WHERE LOWS COULD APPROACH 0 DEGREES WHILE EAST CENTRAL KANSAS WILL PROBABLY REMAIN IN THE TEENS AS WINDS ARE EXPECTED TO KEEP THINGS MIXED THROUGH SUNRISE. THE NEXT UPPER LEVEL SYSTEM WILL MOVE OUT INTO THE ROCKIES BY LATE SATURDAY WITH LEE CYCLOGENESIS IN EASTERN COLORADO. SOUTHERLY RETURN FLOW WILL KICK UP ACROSS KANSAS WITH A BIT OF WARM ADVECTION AS WELL. TEMPS WILL WARM TO NEAR FREEZING OR A BIT WARMER IN ANY AREAS FREE OF SNOW COVER BUT IT WILL STILL FEEL CHILLY WITH THE BREEZE. BARJENBRUCH SUNDAY THROUGH FRIDAY...STRONG WARM AIR ADVECTION STARTS UP ON SUNDAY AS SOUTHERLY FLOW IN RESPONSE TO A DEEPENING SURFACE TROUGH MOVES INTO THE AREA. EXPECT A FAIRLY SIGNIFICANT JUMP IN TEMPERATURES FROM SATURDAY TO SUNDAY...AS HIGHS ON SUNDAY COULD REACH INTO THE LOWER 50S...ESPECIALLY SOUTH AND EAST OF THE TURNPIKE. AREAS NORTH AND WEST OF THE TURNPIKE WILL LIKELY REACH INTO THE MID TO UPPER 40S. ALTHOUGH THERE WILL BE SOME ISENTROPIC LIFT ASSOCIATED WITH THE STRONG WARM AIR ADVECTION MARGINAL MOISTURE RETURN AS INDICATED BY CONDENSATION PRESSURE DEFICITS WELL ABOVE 100 MB ON ALL ANALYZED ISENTROPIC SURFACES WILL PRECLUDE WARM AIR ADVECTION SHOWERS ON SUNDAY MORNING. AS THE PARENT UPPER TROUGH DIGS SOUTHWARD ENOUGH FORCING FOR ASCENT WILL BE PRESENT ALONG THE LEADING 500 MB VORTICITY MAXIMUM THAT PRECIPITATION SHOULD COMMENCE ACROSS THE AREA AROUND 18Z ON SUNDAY...MAINLY IN NORTH CENTRAL KANSAS. PRECIP WILL SPREAD EASTWARD THROUGHOUT THE REST OF THE AFTERNOON ON SUNDAY...STARTING MAINLY AS RAIN...THEN SWITCHING OVER TO A RAIN/SNOW MIXTURE. THERMAL PROFILES INDICATE THAT NORTHEAST KANSAS COULD SEE A BRIEF WINDOW WHERE SNOWFALL COULD OCCUR...HOWEVER GIVEN THE MARGINAL SIGNALS FOR SNOW IN THE FORECAST SOUNDINGS WILL CARRY A MIXTURE OF RAIN/SNOW MIX IN THE FORECAST FOR SUNDAY EVENING. COLDER AIR MORE CONDUCIVE TO PURE SNOW FORMATION WILL MOVE INTO FAR NORTHEAST KANSAS BY SUNDAY NIGHT LIKELY BRINGING A PERIOD OF PURE SNOW TO AREAS NORTH OF INTERSTATE 70 ON WEDNESDAY NIGHT. EXPECT THE UPPER TROUGH TO MOVE OUT OF THE AREA BY MONDAY MORNING WHICH WILL CAUSE PRECIP TO COME TO AN END BY EARLY MONDAY MORNING. EXPECT MILD CONDITIONS TO PERSIST AFTER THE RAIN/SNOW ENDS ON SUNDAY...AS SHORTWAVE RIDGING MOVES INTO THE AREA FOR THE BEGINNING TO MIDDLE PART OF THE WORK WEEK. THE NEXT CHANCE FOR PRECIP LOOKS TO TAKE SHAPE TUESDAY NIGHT INTO WEDNESDAY MORNING AS STRONG WARM/MOIST AIR ADVECTION PUSHES INTO THE AREA AHEAD OF THE NEXT UPPER TROUGH. INTRODUCED PRECIP FOR LATE TUESDAY NIGHT INTO WEDNESDAY MORNING LASTING ROUGHLY THROUGH WEDNESDAY AFTERNOON. ONCE AGAIN THERMAL PROFILES INDICATE A MARGINAL PRECIP TYPE EVENT...MEANING A RAIN/SNOW MIXTURE IS EXPECTED FROM THIS EVENT ON TUESDAY/WEDNESDAY. EVEN THOUGH PRECIP IS EXPECTED THROUGH TUESDAY AND WEDNESDAY EXPECT HIGHS ALL WEEK TO REACH THE MID 40S TO POSSIBLY EVEN LOWER 50S. JL && .TOP WATCHES/WARNINGS/ADVISORIES...NONE. && $$
AREA FORECAST DISCUSSION
NWS GLASGOW MT
1049 PM MST FRI JAN 20 2012 .SHORT TERM...FOR NORTHEAST MONTANA...TONIGHT THROUGH SUNDAY... NO APPARENT PRECIPITATION UPSTREAM AND THE HRRR MODEL KEEPS OUR AREA DRY TONIGHT...SO REMOVED POPS FROM MOST OF THE AREA...EXCEPT A SLIGHT CHANCE STRIP ALONG THE INTERNATIONAL BORDER. HOWEVER TEMPERATURES UPSTREAM HAVE WARMED CONSIDERABLY. THE NAM12 MODEL WAS USED FOR THE DIURNAL TRENDS FOR TONIGHT AND SATURDAY DUE TO EXPECTED RISING TEMPERATURES FROM THE SW. BLENDED THE HRRR WINDS INTO THE GRIDS TO INCREASE WINDS IN FAVORED AREAS FOR SE DIRECTION. SCT PREVIOUS DISCUSSION... WARMER CONDITIONS ARE EXPECTED THIS TERM WITH ABOVE NORMAL READINGS EXPECTED FOR THE FIRST TIME SINCE SUNDAY. A STRONG PACIFIC SYSTEM HAS PUSHED ONSHORE IN THE PACIFIC NW WITH A WARM FRONT NOW MOVING NE THROUGH SW MONTANA. THIS FRONT IS EXPECTED TO CONTINUE NE ALLOWING TEMPS TO RISE TONIGHT. 850 MB TEMPS RISE SIGNIFICANTLY AS THE REMAINING ARCTIC AIR-MASS GETS NUDGED TO OUR NE...WITH READINGS OVER GLASGOW RISING FROM ABOUT -12*C THIS AFTERNOON TO +3*C SATURDAY MORNING. LOW PRESSURE WILL BEGIN TO DEVELOP OVER SOUTHERN ALBERTA SATURDAY AS THE UPPER TROUGH MOVES IN. THE MODELS THEN TAKE THIS LOW EAST NEAR THE INTERNATIONAL BORDER...FAR ENOUGH NORTH FOR THE MILD PACIFIC AIR-MASS TO FLOOD INTO THE AREA SATURDAY. OF COURSE SNOW-COVER WILL TEMPER THIS WITH FURTHER COOLING IN THE NORTHERN ZONES DUE TO LACK OF MIXING. MOISTURE AHEAD OF THIS SYSTEM LOOKS MINIMAL SO SLIGHT CHANCE POPS LOOK GOOD FOR NOW. MODELS SEEM TO PUT A FINGER THOUGH ON SOME DEVELOPMENT SATURDAY AFTERNOON IN THE SOUTHEAST ZONES. THIS AREA QUICKLY MOVES EAST TO CREATE A HEADACHE FOR AREAS THERE. THE UPPER TROUGH LATE SATURDAY INTO SUNDAY WRAPS UP A BIT...ESPECIALLY ON THE GFS. THIS MODEL HAS BEEN CONSISTENT AND KNOCKS TEMPS BACK DOWN ACROSS THE AREA...AND MIXING NW WINDS TO THE SURFACE AS WELL. SOME SNOW-SHOWER ACTIVITY CAN BE EXPECTED TOO...SPREADING FROM NW TO SE DURING THE MORNING. SNOWFALL LOOKS TO BE LESS THAN AN INCH. JAMBA .LONG TERM...SUNDAY NIGHT THROUGH FRIDAY... NOT TOO MANY CHANGES TO THE LONG TERM...WITH THE MAIN FOCUS BEING THE RETURN OF THE POSSIBILITY OF ABOVE AVERAGE TEMPERATURES NEXT WEEK. BRIEF RIDGING STILL LOOKS TO MOVE IN EARLY IN THE WORK WEEK...FOLLOWED BY A SERIES OF SHORTWAVE TROUGHS. DECIDED TO RAISE TEMPS A BIT FOR NEXT WEEK DUE TO THE MAJORITY OF MODEL GUIDANCE HINTING TOWARDS WARMER TEMPERATURES COMPARED TO PREVIOUS RUNS. THE CHALLENGE WILL STILL BE FIGURING OUT JUST HOW WARM WE WILL GET...ESPECIALLY WITH A FEW BRIEF SHOTS OF COLD AIR WITH THE PASSING SHORTWAVES AND CORRESPONDING COLD FRONTS. ALTHOUGH WINDS STILL LOOK TO BE STRONG LATER IN THE PERIOD...THE AMOUNT OF MIXING STILL MAY PREVENT US FROM BRINGING THE WARMER AIR DOWN TO THE SURFACE. FORECASTED HIGHS ARE STILL A BIT BELOW MOST MODEL SOLUTIONS. WEDNESDAY STILL LOOKS TO BE THE WARMEST DAY NEXT WEEK...WITH THE GFS BRINGING 850 TEMPS AROUND 4C TO 8C OVER THE CWA. HOWEVER...THE 12Z ECMWF SUGGESTS THAT WEDNESDAY AND THURSDAY LOOK TO BE WARM...WITH THURSDAY BEING THE WARMER OF THE TWO DAYS. 850 TEMPS ARE JUST A BIT HIGHER ON THURSDAY ACCORDING TO THE ECMWF BY ABOUT 2C TO 4C COMPARED TO WEDNESDAY. EITHER WAY...NEXT WEEK STILL LOOKS TO BE A WELCOMED RETURN TO WARMER TEMPERATURES. BARNWELL PREVIOUS LONG TERM DISCUSSION...PATTERN RETURNS TO WHAT HAS BEEN COMMON THIS WINTER...ZONAL FLOW OFF THE PACIFIC WITH A SERIES OF WEAK RIDGES AND TROF...AND ARCTIC AIRMASS STAYING WELL TO THE NORTH. MODEL TIMING OF THE FEATURES NOT TOO FAR OFF FROM EACH OTHER...ALTHOUGH THIS DOES SLIP TOWARD THE END OF THE FORECAST PERIOD. UPPER TROF EXITING THE REGION SUNDAY NIGHT WITH RIDGE SLIDING ACROSS THE STATE ON MONDAY WITH ANOTHER TROF PUSHING THROUGH THE PACIFIC NORTHWEST. COLD FRONT IS PUSHED INTO THE STATE MONDAY NIGHT AS UPPER TROF TRACKS ALONG THE CANADIAN BORDER. JET PUNCHES INTO WESTERN CANADA BEHIND THE TROF ON TUESDAY NIGHT..DEVELOPING INTO A STRONG CHINOOK ACROSS MONTANA ON WEDNESDAY. AS JET DIVES INTO THE NORTHERN PLAINS...COLD FRONT DROPS THROUGH MONTANA...AND ENOUGH DYNAMICS AND MOISTURE FOR A LITTLE PRECIPITATION ON WEDNESDAY. PATTERN REPEATS FOR THURSDAY INTO THURSDAY NIGHT...ALTHOUGH AIRMASS SLIGHTLY COLDER BEHIND THIS SECOND COLD FRONT. POTENTIAL FOR WINDY CONDITIONS WILL BE INCREASING ALTHOUGH MIXING WILL CONTINUE TO BE A PROBLEM...ESPECIALLY WITH INCREASED SNOW COVER IN CONTRAST TO EARLIER IN THE MONTH. EBERT && .AVIATION... THERE WILL BE A SCATTERED TO BROKEN LAYER AROUND 2K FT AGL OVER PARTS OF THE FORECAST AREA TONIGHT...OTHERWISE MAINLY VFR WITH BROKEN TO OVERCAST LAYERS ABOVE 8K FT AGL. E WINDS 10 TO 15 KT AT GGW. SLIGHT CHANCE OF A LITTLE LIGHT FREEZING RAIN LATE TONIGHT AND SATURDAY MORNING. SIMONSEN && .GLASGOW WATCHES/WARNINGS/ADVISORIES...NONE. && $$ WEATHER.GOV/GLASGOW
AREA FORECAST DISCUSSION
NWS HASTINGS NE
1109 PM CST FRI JAN 20 2012 .AVIATION...06Z TAF. DRY CONDITIONS EXPECTED FOR THIS TAF PERIOD...WITH MAIN CONCERNS LYING WITH CLOUD COVER EARLY ON...THEN A SWITCH IN WINDS. CURRENTLY SEEING A SMALL AREA OF LOW LEVEL STRATUS LINGERING OVER THE TERMINAL AREA...RESULTING IN MVFR CIGS. COULD SEE THIS CONTINUE FOR A FEW MORE HOURS...BUT IS EXPECTED TO DIMINISH WITH VFR CONDITIONS RETURNING. THROUGH THE REST OF THE TAF PERIOD ANY CLOUD COVER IS EXPECTED TO REMAIN CONFINED TO THE MID/UPPER LEVELS. AS FAR AS WINDS GO...SPEEDS CONTINUE TO DIMINISH AS SURFACE HIGH PRESSURE DRIFTS EAST THROUGH THE AREA. LATER THIS MORNING WINDS WILL GRADUALLY SWITCH TO THE SOUTH ON THE BACKSIDE OF THE SFC HIGH...AND WILL REMAIN SOUTHERLY THROUGH THE REMAINDER OF THE TAF PERIOD. A TIGHTENING PRESSURE GRADIENT DEVELOPING ACROSS THE AREA WILL BRING INCREASING SPEEDS THROUGH THE DAYTIME HOURS...WITH SPEEDS THIS AFTERNOON REACHING NEAR 20 TO 25 MPH WITH HIGHER GUSTS. && .PREV DISCUSSION... /ISSUED 1023 PM CST FRI JAN 20 2012/ UPDATE...SOME STRATUS IS MAKING ITS WAY FROM THE NORTH BUT SHOULD EVENTUALLY HAVE A HARD TIME HOLDING TOGETHER DURING THE OVERNIGHT...BUT HAVE INCREASED SKY COVER FOR THE NEXT SEVERAL HOURS. ALSO RAISED TEMPERATURES A BIT...ESPECIALLY IN THE SOUTHWESTERN CWA FOR LOWS TONIGHT. PREV DISCUSSION... /ISSUED 318 PM CST FRI JAN 20 2012/ SHORT TERM...THROUGH 00Z SUNDAY. MORNING UPPER AIR ANALYSIS INDICATES ZONAL TO NORTHWESTERLY UPPER LEVEL FLOW PERSISTING ACROSS MUCH OF THE CONUS. A 90KT MID LEVEL JET AXIS IS ALSO NOTED EXTENDING FROM THE NORTHERN PLAINS TO THE MID-ATLANTIC. WATER VAPOR IMAGERY INDICATES INCREASED MID LEVEL MOISTURE ACROSS THE NORTHERN HALF OF THE CONUS...WITH A TROPICAL MID LEVEL MOISTURE TAP ALSO NOTED APPROACHING NORTHWESTERN MEXICO FROM THE PACIFIC. AT THE SURFACE A RIDGE OF HIGH PRESSURE REMAINS ANCHORED ACROSS MUCH OF THE PLAINS...WITH AFTERNOON TEMPERATURES REMAINING IN THE 20S ACROSS MUCH OF THE CENTRAL PLAINS. WARMER AIR IS NOT FAR AWAY HOWEVER AS A STRONG LOW LEVEL BAROCLINIC ZONE CURRENTLY EXTENDS ALONG MUCH OF THE HIGH PLAINS...WITH A 20-30 DEGREE TEMPERATURE GRADIENT CURRENTLY EXISTING WITHIN ABOUT 50 MILES ACROSS THE LOW LEVEL BAROCLINIC ZONE. MID AFTERNOON SATELLITE IMAGERY INDICATES ALTO-STRATUS OVER SOUTH DAKOTA...MOVING SOUTH/SOUTHEAST INTO NORTHERN NEBRASKA. SATELLITE IMAGERY ALSO INDICATES THE WESTERN EDGE OF THIS CLOUD DECK IS ERODING...THUS MAKING IT APPEAR AS THOUGH WE STAND A BETTER CHANCE OF RECEIVING A GLANCING BLOW ACROSS OUR NORTHEASTERN CWA RATHER THAN BE COMPLETELY OVERTAKEN BY CLOUDS THIS EVENING. THIS ALSO FITS WELL WITH THE LATEST RUC GUIDANCE...WHICH INDICATES ISENTROPIC DOWN GLIDE IS INFILTRATING MUCH OF THE REGION. GIVEN ALL THIS...WILL KEEP MOSTLY CLOUDY SKIES GOING ACROSS OUR NORTHEAST THROUGH LATE EVENING...WITH LOCATIONS FARTHER SOUTHWEST HOPEFULLY REMAINING WEST/SOUTHWEST OF THE CLOUD DECK. THIS WILL BE SOMETHING FOR THE EVENING SHIFT TO MONITOR HOWEVER...JUST IN CASE THE CLOUD DECK DOES MANAGE TO PUSH FARTHER SOUTHWEST THAN CURRENTLY FORECAST. CLEARING SKIES...DECREASING LOW LEVEL WINDS AND WEAK SURFACE RIDGING SHOULD PROMOTE A DECENT DROP OFF IN TEMPERATURES TONIGHT AND CURRENTLY HAVE 20-25 DEGREE DROP OFFS IN THE FORECAST...WHICH YIELDS OVERNIGHT LOWS IN THE SINGLE DIGITS. THE SURFACE RIDGE IS EXPECTED TO PUSH OFF TO THE EAST EARLY SATURDAY MORNING...WITH LOW LEVEL RETURN FLOW REESTABLISHED ACROSS THE CENTRAL PLAINS BY SUNRISE SATURDAY. THIS LOW LEVEL RETURN FLOW WILL PROMOTE WEAK LOW LEVEL WAA WITHIN A SOUTH/SOUTHEASTERLY LOW LEVEL WIND FIELD. ~25 DEGREE RISES ARE EXPECTED FOR THE MOST PART SATURDAY...WHICH YIELDS SATURDAY AFTERNOON HIGHS IN THE UPPER 20S TO UPPER 30S ACROSS THE CWA. LONG TERM...00Z SUNDAY THROUGH FRIDAY. THE START OF THE LONG TERM PERIOD WILL FEATURE AN H5 RIDGE ACROSS THE CENTRAL UNITED STATES WITH A LARGE TROUGH IN THE WEST. THERE IS GENERAL CONSENSUS THAT THE WESTERN U.S. TROUGH WILL MOVE ACROSS THE CENTRAL PLAINS LATE SATURDAY NIGHT INTO SUNDAY...HOWEVER FINDING AGREEMENT IN THE DETAILS REMAINS ELUSIVE. DIFFERENCES REMAIN AMONGST THE VARIOUS MODEL SOLUTIONS IN THE OVERALL STRENGTH/TIMING WHICH OBVIOUSLY HAVE LARGE IMPACTS IN REGARDS TO POPS AND PRECIPITATION TYPE. AT THIS POINT...HAVE CONTINUED TO CARRY A BLENDED MODEL SOLUTION WHICH GIVES POPS GENERALLY IN THE 30 PERCENT RANGE ON SUNDAY. THIS ALSO LINGERS A POP IN THE FAR EAST FOR SUNDAY EVENING WHICH ACCOUNTS FOR SOME OF THE SLOWER MODEL SOLUTIONS...IN PARTICULAR THE ECMWF. TEMPERATURES AND THE OVERALL THERMAL PROFILE REMAINS UNCERTAIN THOUGH THE GENERAL TREND SEEMS TO KEEP WARMER H85 TEMPERATURES IN THE MORNING...FOLLOWED BY COLDER AIR ARRIVING BEHIND A COLD FRONT IN THE AFTERNOON. IF PRECIPITATION STARTS EARLY ENOUGH ON SUNDAY...COULD SEE SOME POTENTIAL FOR LIGHT FREEZING RAIN DUE TO THE EXPECTED BELOW FREEZING SURFACE TEMPERATURES...BUT WITH CONFIDENCE STILL SO LOW IN THE DETAILS...WILL INSTEAD OPT FOR A RAIN/SNOW MIX. IN FACT...COULD SEE SOME JUSTIFICATION FOR A RAIN/SNOW MIX MUCH OF THE DAY DEPENDING ON THE TIMING OF THE COLDER AIR ALOFT. IN REGARDS TO SUNDAY EVENING...WILL GO WITH SNOW SINCE MOST SOLUTIONS HAVE THE COLD AIR IN PLACE BY THAT TIME. ANOTHER CONCERN ON SUNDAY WILL BE STRONG WINDS BEHIND THE COLD FRONT. STRONG PRESSURE RISES ARE SHOWN ACROSS THE FORECAST AREA. MOMENTUM TRANSFER FROM NAM BUFR SOUNDINGS SUGGEST GUSTS COULD APPROACH 40 KTS ACROSS MUCH OF THE FORECAST AREA...WITH EVEN STRONGER WINDS POTENTIALLY TAKING HOLD IN THE SOUTHWEST. CURRENTLY WE ARE HIGHLIGHTING THE STRONGER WINDS IN THE HAZARDOUS WEATHER OUTLOOK...AND WILL LET THAT WORDING CONTINUE. A DRY PERIOD TAKES HOLD AGAIN FOR OVERNIGHT SUNDAY INTO AT LEAST EARLY TUESDAY AS ANOTHER H5 RIDGE DOMINATES THE CENTRAL PORTION OF THE COUNTRY. THE NEXT WAVE MOVES THROUGH THE AREA TUESDAY INTO TUESDAY NIGHT...HOWEVER AGAIN THERE ARE DIFFERENCES IN TIMING AMONGST THE MODELS. WILL MAINTAIN CONTINUITY FOR NOW AND HOLD ONTO THE MAIN PRECIPITATION CHANCES TUESDAY NIGHT. PRECIPITATION TYPE COULD AGAIN BE AN WITH THE GFS COLDER THAN THE ECMWF. HAVE GONE WITH A RAIN/SNOW COMBINATION IN THE SOUTH...BUT WILL GO ALL SNOW IN THE NORTH WHERE EVEN THE WARMER ECMWF DROPS H85 TEMPERATURES BELOW FREEZING TUESDAY EVENING. THE REMAINDER OF THE FORECAST PERIOD APPEARS TO BE GENERALLY SUPPORT ABOVE NORMAL TEMPERATURES WITH HIGHS PRIMARILY IN THE 40S. THE WARMEST DAY COULD TURN OUT TO BE THURSDAY WITH SOME LOCATIONS POTENTIALLY PUSHING THE 50 DEGREE MARK. && .GID WATCHES/WARNINGS/ADVISORIES... NE...NONE. KS...NONE. && $$ AVIATION...ADO UPDATE...HEINLEIN SHORT...BRYANT LONG...KING
AREA FORECAST DISCUSSION
NWS HASTINGS NE
1023 PM CST FRI JAN 20 2012 .UPDATE...SOME STRATUS IS MAKING ITS WAY FROM THE NORTH BUT SHOULD EVENTUALLY HAVE A HARD TIME HOLDING TOGETHER DURING THE OVERNIGHT...BUT HAVE INCREASED SKY COVER FOR THE NEXT SEVERAL HOURS. ALSO RAISED TEMPERATURES A BIT...ESPECIALLY IN THE SOUTHWESTERN CWA FOR LOWS TONIGHT. && .PREV DISCUSSION... /ISSUED 510 PM CST FRI JAN 20 2012/ AVIATION...00Z KGRI TAF. CEILINGS ARE GOING TO BE A TOUGH CALL THIS EVENING. SOME STRATUS ARE HEADING TOWARD THE TERMINAL FROM THE NORTH...BUT ISENTROPIC DOWNGLIDE WILL BE COMPETING AGAINST THE STRATUS HOLDING TOGETHER FOR LONG. LOOKING AT THE LATEST SATELLITE DATA AND SPEED TOOLS...IT APPEARS THAT THE STRATUS SHOULD ARRIVE A BIT OVER AN HOUR AFTER THIS FORECAST IF VALID...BUT WITH ISENTROPIC DOWNGLIDE...WILL LIKELY ONLY HOLD TOGETHER THROUGH THE EVENING AND THEN SCATTER BY THE EARLY OVERNIGHT. WIND WILL SWITCH FROM THE NORTH TO THE SOUTH OVERNIGHT AS A SURFACE HIGH SLIDES EAST. SOUTH WIND CAN GET A BIT GUSTY BY SATURDAY AFTERNOON AS THE SURFACE PRESSURE GRADIENT INCREASES. PREV DISCUSSION... /ISSUED 318 PM CST FRI JAN 20 2012/ SHORT TERM...THROUGH 00Z SUNDAY. MORNING UPPER AIR ANALYSIS INDICATES ZONAL TO NORTHWESTERLY UPPER LEVEL FLOW PERSISTING ACROSS MUCH OF THE CONUS. A 90KT MID LEVEL JET AXIS IS ALSO NOTED EXTENDING FROM THE NORTHERN PLAINS TO THE MID-ATLANTIC. WATER VAPOR IMAGERY INDICATES INCREASED MID LEVEL MOISTURE ACROSS THE NORTHERN HALF OF THE CONUS...WITH A TROPICAL MID LEVEL MOISTURE TAP ALSO NOTED APPROACHING NORTHWESTERN MEXICO FROM THE PACIFIC. AT THE SURFACE A RIDGE OF HIGH PRESSURE REMAINS ANCHORED ACROSS MUCH OF THE PLAINS...WITH AFTERNOON TEMPERATURES REMAINING IN THE 20S ACROSS MUCH OF THE CENTRAL PLAINS. WARMER AIR IS NOT FAR AWAY HOWEVER AS A STRONG LOW LEVEL BAROCLINIC ZONE CURRENTLY EXTENDS ALONG MUCH OF THE HIGH PLAINS...WITH A 20-30 DEGREE TEMPERATURE GRADIENT CURRENTLY EXISTING WITHIN ABOUT 50 MILES ACROSS THE LOW LEVEL BAROCLINIC ZONE. MID AFTERNOON SATELLITE IMAGERY INDICATES ALTO-STRATUS OVER SOUTH DAKOTA...MOVING SOUTH/SOUTHEAST INTO NORTHERN NEBRASKA. SATELLITE IMAGERY ALSO INDICATES THE WESTERN EDGE OF THIS CLOUD DECK IS ERODING...THUS MAKING IT APPEAR AS THOUGH WE STAND A BETTER CHANCE OF RECEIVING A GLANCING BLOW ACROSS OUR NORTHEASTERN CWA RATHER THAN BE COMPLETELY OVERTAKEN BY CLOUDS THIS EVENING. THIS ALSO FITS WELL WITH THE LATEST RUC GUIDANCE...WHICH INDICATES ISENTROPIC DOWN GLIDE IS INFILTRATING MUCH OF THE REGION. GIVEN ALL THIS...WILL KEEP MOSTLY CLOUDY SKIES GOING ACROSS OUR NORTHEAST THROUGH LATE EVENING...WITH LOCATIONS FARTHER SOUTHWEST HOPEFULLY REMAINING WEST/SOUTHWEST OF THE CLOUD DECK. THIS WILL BE SOMETHING FOR THE EVENING SHIFT TO MONITOR HOWEVER...JUST IN CASE THE CLOUD DECK DOES MANAGE TO PUSH FARTHER SOUTHWEST THAN CURRENTLY FORECAST. CLEARING SKIES...DECREASING LOW LEVEL WINDS AND WEAK SURFACE RIDGING SHOULD PROMOTE A DECENT DROP OFF IN TEMPERATURES TONIGHT AND CURRENTLY HAVE 20-25 DEGREE DROP OFFS IN THE FORECAST...WHICH YIELDS OVERNIGHT LOWS IN THE SINGLE DIGITS. THE SURFACE RIDGE IS EXPECTED TO PUSH OFF TO THE EAST EARLY SATURDAY MORNING...WITH LOW LEVEL RETURN FLOW REESTABLISHED ACROSS THE CENTRAL PLAINS BY SUNRISE SATURDAY. THIS LOW LEVEL RETURN FLOW WILL PROMOTE WEAK LOW LEVEL WAA WITHIN A SOUTH/SOUTHEASTERLY LOW LEVEL WIND FIELD. ~25 DEGREE RISES ARE EXPECTED FOR THE MOST PART SATURDAY...WHICH YIELDS SATURDAY AFTERNOON HIGHS IN THE UPPER 20S TO UPPER 30S ACROSS THE CWA. LONG TERM...00Z SUNDAY THROUGH FRIDAY. THE START OF THE LONG TERM PERIOD WILL FEATURE AN H5 RIDGE ACROSS THE CENTRAL UNITED STATES WITH A LARGE TROUGH IN THE WEST. THERE IS GENERAL CONSENSUS THAT THE WESTERN U.S. TROUGH WILL MOVE ACROSS THE CENTRAL PLAINS LATE SATURDAY NIGHT INTO SUNDAY...HOWEVER FINDING AGREEMENT IN THE DETAILS REMAINS ELUSIVE. DIFFERENCES REMAIN AMONGST THE VARIOUS MODEL SOLUTIONS IN THE OVERALL STRENGTH/TIMING WHICH OBVIOUSLY HAVE LARGE IMPACTS IN REGARDS TO POPS AND PRECIPITATION TYPE. AT THIS POINT...HAVE CONTINUED TO CARRY A BLENDED MODEL SOLUTION WHICH GIVES POPS GENERALLY IN THE 30 PERCENT RANGE ON SUNDAY. THIS ALSO LINGERS A POP IN THE FAR EAST FOR SUNDAY EVENING WHICH ACCOUNTS FOR SOME OF THE SLOWER MODEL SOLUTIONS...IN PARTICULAR THE ECMWF. TEMPERATURES AND THE OVERALL THERMAL PROFILE REMAINS UNCERTAIN THOUGH THE GENERAL TREND SEEMS TO KEEP WARMER H85 TEMPERATURES IN THE MORNING...FOLLOWED BY COLDER AIR ARRIVING BEHIND A COLD FRONT IN THE AFTERNOON. IF PRECIPITATION STARTS EARLY ENOUGH ON SUNDAY...COULD SEE SOME POTENTIAL FOR LIGHT FREEZING RAIN DUE TO THE EXPECTED BELOW FREEZING SURFACE TEMPERATURES...BUT WITH CONFIDENCE STILL SO LOW IN THE DETAILS...WILL INSTEAD OPT FOR A RAIN/SNOW MIX. IN FACT...COULD SEE SOME JUSTIFICATION FOR A RAIN/SNOW MIX MUCH OF THE DAY DEPENDING ON THE TIMING OF THE COLDER AIR ALOFT. IN REGARDS TO SUNDAY EVENING...WILL GO WITH SNOW SINCE MOST SOLUTIONS HAVE THE COLD AIR IN PLACE BY THAT TIME. ANOTHER CONCERN ON SUNDAY WILL BE STRONG WINDS BEHIND THE COLD FRONT. STRONG PRESSURE RISES ARE SHOWN ACROSS THE FORECAST AREA. MOMENTUM TRANSFER FROM NAM BUFR SOUNDINGS SUGGEST GUSTS COULD APPROACH 40 KTS ACROSS MUCH OF THE FORECAST AREA...WITH EVEN STRONGER WINDS POTENTIALLY TAKING HOLD IN THE SOUTHWEST. CURRENTLY WE ARE HIGHLIGHTING THE STRONGER WINDS IN THE HAZARDOUS WEATHER OUTLOOK...AND WILL LET THAT WORDING CONTINUE. A DRY PERIOD TAKES HOLD AGAIN FOR OVERNIGHT SUNDAY INTO AT LEAST EARLY TUESDAY AS ANOTHER H5 RIDGE DOMINATES THE CENTRAL PORTION OF THE COUNTRY. THE NEXT WAVE MOVES THROUGH THE AREA TUESDAY INTO TUESDAY NIGHT...HOWEVER AGAIN THERE ARE DIFFERENCES IN TIMING AMONGST THE MODELS. WILL MAINTAIN CONTINUITY FOR NOW AND HOLD ONTO THE MAIN PRECIPITATION CHANCES TUESDAY NIGHT. PRECIPITATION TYPE COULD AGAIN BE AN WITH THE GFS COLDER THAN THE ECMWF. HAVE GONE WITH A RAIN/SNOW COMBINATION IN THE SOUTH...BUT WILL GO ALL SNOW IN THE NORTH WHERE EVEN THE WARMER ECMWF DROPS H85 TEMPERATURES BELOW FREEZING TUESDAY EVENING. THE REMAINDER OF THE FORECAST PERIOD APPEARS TO BE GENERALLY SUPPORT ABOVE NORMAL TEMPERATURES WITH HIGHS PRIMARILY IN THE 40S. THE WARMEST DAY COULD TURN OUT TO BE THURSDAY WITH SOME LOCATIONS POTENTIALLY PUSHING THE 50 DEGREE MARK. && .GID WATCHES/WARNINGS/ADVISORIES... NE...NONE. KS...NONE. && $$ AVIATION/UPDATE...HEINLEIN SHORT TERM...BRYANT LONG TERM...KING
AREA FORECAST DISCUSSION
NWS RALEIGH NC
315 AM EST SAT JAN 21 2012 .SYNOPSIS... AN AREA OF LOW PRESSURE AND ITS ASSOCIATED FRONTAL SYSTEM WILL BRING UNSETTLED WEATHER TO THE CAROLINAS AND SOUTHERN VIRGINIA THROUGH TONIGHT. AN AREA OF HIGH PRESSURE WILL BUILD SOUTH INTO OUR REGION SUNDAY...BRINGING DAMP AND CHILLY CONDITIONS. A COLD FRONT WILL CROSS THE AREA ON MONDAY. && .NEAR TERM /THROUGH SUNDAY NIGHT/... AS OF 925 PM FRIDAY... THROUGH SATURDAY NIGHT: LIGHT RAIN AND A WEDGE LIKE AIR MASS HAVE DEVELOPED FROM CENTRAL NORTH CAROLINA TO NORTHERN GA THIS EVENING...WHILE A WARM FRONT IS STARTING TO LIFT THROUGH AL AS A WEAK LOW PRESSURE DEVELOPS OVER ARKANSAS. THE LIGHT RAIN...SUPPORTED BY ISENTROPIC LIFT ALONG AND NORTH OF THE WEDGE FRONT/WEAK 850 MILLIBAR WARM FRONT AND DIFFLUENT FLOW IN THE EXIT OF A WEAK 300MB JET AXIS STRETCHED ACROSS THE LOWER MISSISSIPPI VALLEY...CONTINUES TO BLOSSOM TO OUR SOUTHWEST AND SPREAD ACROSS CENTRAL NORTH CAROLINA. THE ONGOING RAINFALL IS LIGHT AND RAINFALL TOTALS HAVE BEEN BELOW A TENTH OF AN INCH. RUC ISENTROPIC LIFT FORECASTS SHOW STRONG LIFT CONTINUING IN THE 290 TO 300 KELVIN LAYER THROUGH 09Z BEFORE SOME DRIER AIR ALOFT..NOTED AT 700MB...ADVECTS IN FROM THE SOUTHWEST AHEAD OF THE TROUGH AXIS TO APPROACH LATER IN THE DAY SATURDAY. THUS..RAIN IS LIKELY TO TURN TO DRIZZLE FROM WEST TO EAST AFTER 09Z..BUT CATEGORICAL POPS SEEM NECESSARY EVERYWHERE FOR THE BALANCE OF THE NIGHT. WITH A 5000 FOOT WEDGE AIR MASS (PER 00Z KGSO RAOB) LOCKING IN...THE CURRENT FORECAST OF TEMPERATURES IN THE LOW TO MID 40S WILL REMAINING NEARLY STEADY OR RISING SLIGHTLY LOOKS GOOD. -SMITH THE WARM ADVECTION DRIVEN PRECIPITATION SHOULD COME TO AN END FROM WEST TO EAST BY EARLY SATURDAY MORNING. HOWEVER...THE LULL IN PRECIPITATION WILL BE SHORT LIVED AS A COLD FRONT ADVANCES TOWARDS THE AREA DURING THE DAY ON SATURDAY. SOUTHWESTERLY FLOW AHEAD OF THE FRONT WILL PUMP WARM AND MOIST AIR INTO THE REGION...WITH MAX TEMPERATURES EXPECTED TO RISE INTO THE 60S AREAWIDE (MAYBE EVEN PUSHING 70 DEGREES ACROSS THE SOUTHEAST). ALTHOUGH SOME DIURNAL DESTABILIZATION IS EXPECTED TO OCCUR ACROSS THE EASTERN HALF OF THE FORECAST AREA...DEWPOINTS ARE ONLY EXPECTED TO REACH INTO THE LOW TO MID 50S...THUS LIMITING THE AMOUNT OF INSTABILITY. NAM FORECAST SOUNDINGS SHOW AT BEST CAPE VALUES OF LESS THAN 500 J/KG...WHILE THE GFS FORECAST SOUNDINGS SHOW NO INSTABILITY AT ALL. NEVERTHELESS...DECENT SHEAR WILL BE IN PLACE OVER THE REGION AND IF WE ARE ABLE TO REALIZE SOME OF THE INSTABILITY THE NAM INDICATES...AN ISOLATED THUNDERSTORM OR TWO CANNOT BE RULED OUT SATURDAY AFTERNOON. HOWEVER...FOR NOW WILL LEAVE ANY MENTION OF THUNDER OUT OF THE FORECAST DUE TO THE UNCERTAINTY. OVERALL...AFTER THE BRIEF LULL IN PRECIPITATION SATURDAY MORNING...AM EXPECTING A LINE OF SHOWERS TO PROGRESS FROM NORTHWEST TO SOUTHEAST SATURDAY AFTERNOON/EVENING. SUN AND SUN NIGHT: A STRENGTHENING 1030 MILLIBAR PLUS SURFACE COLD AIR HIGH OVER NEW ENGLAND WILL ADVECT COLDER AND DRIER AIR INTO CENTRAL NORTH CAROLINA DURING THE PREDAWN HOURS...AND THIS WILL SET THE STAGE FOR A SHORT LIVED HYBRID DAMMING EVENT ON SUNDAY AS CONTINUED SOUTHWEST FLOW ALOFT WILL SUPPORT WEAK OVERRUNNING ACROSS CENTRAL NORTH CAROLINA AS THE NEXT PACIFIC TROUGH PUSHES EAST INTO THE CENTRAL UNITED STATES. WITH MOIST COLUMN NOT EXTENDING MUCH BEYOND 700 MILLIBAR...LITTLE TO NO ADDITIONAL ACCUMULATIONS ARE EXPECTED WITH PERIODS OF DRIZZLE THROUGHOUT THE DAY...WITH THE POTENTIAL THAT THE NORTHWEST PIEDMONT COULD SEE A BRIEF PERIOD OF FREEZING DRIZZLE EARLY SUNDAY MORNING AS MODEL SOUNDINGS DRIVE SURFACE TEMPERATURES SUNDAY MORNING INTO THE LOWER TO MID 30S WITH WET BULB FREEZING LINE DEPICTED IN THE SAME CLIMATOLOGICALLY FAVORED AREA AS WELL. FURTHERMORE A HANDFUL OF SREF MEMBERS ALSO INDICATE A BRIEF CHANGEOVER OF FREEZING DRIZZLE WITH LITTLE TO NO ACCUMULATION( A COUPLE OF HUNDREDTHS OR LESS). SURFACE WET BULBS ARE EXPECTED TO REBOUND INTO THE MID 30S THROUGH THE MORNING WITH MINIMAL RECOVERY THROUGHOUT THE DAY. AFTER MORNING LOWS IN THE MID TO UPPER 30S NORTH TO MID 40S SOUTH...EXPECT A NET INCREASE OF ONLY 3 TO 5 DEGREES ACROSS THE AREA. STALLED FRONTAL ZONE SOUTH OF THE AREA BEGINS TO RETREAT NORTHWARD AS A WARM FRONT SUNDAY NIGHT...WITH THE SOUTHERN RETURN FLOW OVERTAKING THE SHALLOW COLD AIR DAMMING AIR MASS ALONG THE SOUTHERN AND EASTERN FLANKS...WHILE REMAINING LOCKED IN OVER THE NORTHWEST PIEDMONT REGION. THIS WILL FAVOR NEAR STEADY TEMPERATURES OVERNIGHT ACROSS THE NORTHWEST WITH TEMPERATURES SLIGHTLY RISING ACROSS THE SANDHILLS AND COASTAL COUNTIES. && .SHORT TERM /MONDAY AND MONDAY NIGHT/... AS OF 250 AM SATURDAY... MON AND MON NIGHT: A TRANSITION FROM A FORMIDABLE CAD REGIME -- BY THIS TIME AN IN-SITU ONE OWING TO THE QUICK DEPARTURE OF THE PROGRESSIVE PARENT HIGH -- TO BRIEF WARM SECTOR OVER AT LEAST SIZABLE PORTION OF CENTRAL NC...TO A COLD FRONTAL PASSAGE...WILL ALL OCCUR IN LESS THAN 24 HOURS THIS PERIOD. THE WEDGE IS EXPECTED TO QUICKLY ERODE ALONG THE EDGES WHERE THE CHARACTERISTIC STABILITY AND DEPTH ARE LOWER THROUGH MIDDAY...BUT HOLD STUBBORNLY IN THE HEART OF THE WEDGE OVER THE NW PIEDMONT INTO THE EARLY AFTERNOON HOURS...BEST REPRESENTED BY THE 00Z ECMWF AND NAM/WRF (DESPITE THE NAM/WRF DISCOUNTED SOLUTION OF A MUCH FARTHER NORTHWARD-DISPLACED SURFACE LOW IN SOUTHERN CANADA...AS OPPOSED TO THE CONSENSUS OF OTHER GUIDANCE WHICH HAS THE LOW IN THE UPPER MIDWEST). AS SUCH...TEMPERATURES SHOULD WARM INTO THE UPPER 60S-LOWER 70S IN WAA AND A FEW BINOVC OVER EASTERN NC...INCLUDING THE RAH COASTAL PLAIN...WHILE THE NW PIEDMONT IS APT TO STRUGGLE THROUGH THE 40S FOR MUCH OF THE DAY...AND TOP OUT ONLY IN THE MID-UPPER 50S FOR A COUPLE OF HOURS VERY LATE IN THE AFTERNOON. NWP GUIDANCE INDICATES ONLY A BRIEF PERIOD OF DEEP MOISTENING AND MID LEVEL CAP EROSION IMMEDIATELY AHEAD OF THE FRONT...AND EVEN THEN LAPSE RATES ARE PROJECTED TO REMAIN PSEUDO-MOIST ADIABATIC OWING TO THE PASSAGE OF THE PARENT NEGATIVELY-TILTED S/W TROUGH AND ACCOMPANYING CAA ALOFT TO THE NW OF THE WARM SECTOR OVER CENTRAL AND EASTERN NC. AS SUCH...THUNDER POTENTIAL IS QUITE LOW...AND THE PROBABILITY OF SHOWERS WILL BE HELD IN THE 30-60 PERCENT RANGE...HIGHEST NORTH AND NORTHWEST IN CLOSER PROXIMITY TO BOTH THE S/W TROUGH ALOFT AND THE RETREATING/ERODING WEDGE FRONT. TIMING DIFFERENCES REMAIN WRT THE FRONTAL PASSAGE AND FOLLOWING CAA MON NIGHT...SO ONLY MINOR MODIFICATION TO LOWS IN THE UPPER 30S TO MID-UPPER 40S WAS JUSTIFIED. && .LONG TERM /TUESDAY THROUGH FRIDAY/... AS OF 310 AM SATURDAY... TUE THROUGH FRI: MILD POST-FRONTAL HIGH PRESSURE WILL FOLLOW FOR THE MIDDLE OF THE WEEK...WITH TEMPERATURES RANGING FROM THE UPPER 50S TO MIDDLE 60S FOR HIGHS...WARMEST THU. NWP GUIDANCE CONTINUES TO INDICATE THE FRONTAL ZONE FORECAST TO CROSS OUR REGION MON NIGHT WILL STALL OVER THE GULF COAST...BUT SOLUTIONS VARY WILDLY WRT TO HOW QUICKLY AND PHASED WITH THE NORTHERN STREAM (IF AT ALL) A SOUTHERN STREAM UPPER LOW WILL PROGRESS EASTWARD AND ACTIVATE THE STALLED FRONTAL ZONE WITH OUR ENSUING NEXT CHANCE OF RAIN. WILL ACCORDINGLY MAINTAIN FORECAST CONTINUITY FROM PREVIOUS SHIFTS...WHICH DEPICTS SLIGHT TO LOW CHANCE PROBABILITIES WED NIGHT ONWARD AND ACCOUNTS FOR THE INHERENT FORECAST UNCERTAINTY. HOWEVER...REALISTICALLY THERE WILL BE ONLY A COUPLE OF RELATIVELY BRIEF BOUTS...ON THE ORDER OF SIX HOURS AT A TIME...OF RAINFALL DURING THE ENTIRE PERIOD - ONE WITH THE NORTHWARD RETREAT OF THE FRONTAL ZONE AHEAD OF THE INEVITABLE SURFACE LOW ATTENDING THE SOUTHERN STREAM...AND ANOTHER WITH THE TRAILING COLD FRONT. && .AVIATION /06Z SATURDAY THROUGH WEDNESDAY/... AS OF 120 AM... MOSTLY LIFR CEILINGS NORTHWEST PIEDMONT WITH IFR TO MVFR ELSEWHERE. MOSTLY MVFR VISIBILITIES IN AREAS OF RAIN. SOME IMPROVEMENT IN CEILINGS AFTER SUNRISE... ESPECIALLY LATE AFTERNOON INTO EARLY EVENING AS CHARACTER OF PRECIPITATION CHANGES FROM RAIN TO SHOWERS. CONDITIONS DETERIORATE IN THE EARLY EVENING TO IFR TO MVFR CEILINGS WITH MVFR VISIBILITIES IN PRECIPITATION. SUB VFR CONDITIONS DOMINATE INTO MONDAY MORNING. THEN VFR INTO WEDNESDAY EVENING. && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ NEAR TERM...SMITH/KRR SHORT TERM...MWS LONG TERM...MWS
AREA FORECAST DISCUSSION
NWS RALEIGH NC
121 AM EST SAT JAN 21 2012 .SYNOPSIS... AN AREA OF LOW PRESSURE AND ITS ASSOCIATED FRONTAL SYSTEM WILL BRING UNSETTLED WEATHER TO THE CAROLINAS AND SOUTHERN VIRGINIA THROUGH TONIGHT. AN AREA OF HIGH PRESSURE WILL BUILD SOUTH INTO OUR REGION SUNDAY...BRINGING DAMP AND CHILLY CONDITIONS. A COLD FRONT WILL CROSS THE AREA ON MONDAY. && .NEAR TERM /THROUGH SUNDAY NIGHT/... AS OF 925 PM FRIDAY... THROUGH SATURDAY NIGHT: LIGHT RAIN AND A WEDGE LIKE AIR MASS HAVE DEVELOPED FROM CENTRAL NORTH CAROLINA TO NORTHERN GA THIS EVENING...WHILE A WARM FRONT IS STARTING TO LIFT THROUGH AL AS A WEAK LOW PRESSURE DEVELOPS OVER ARKANSAS. THE LIGHT RAIN...SUPPORTED BY ISENTROPIC LIFT ALONG AND NORTH OF THE WEDGE FRONT/WEAK 850 MILLIBAR WARM FRONT AND DIFFLUENT FLOW IN THE EXIT OF A WEAK 300MB JET AXIS STRETCHED ACROSS THE LOWER MISSISSIPPI VALLEY...CONTINUES TO BLOSSOM TO OUR SOUTHWEST AND SPREAD ACROSS CENTRAL NORTH CAROLINA. THE ONGOING RAINFALL IS LIGHT AND RAINFALL TOTALS HAVE BEEN BELOW A TENTH OF AN INCH. RUC ISENTROPIC LIFT FORECASTS SHOW STRONG LIFT CONTINUING IN THE 290 TO 300 KELVIN LAYER THROUGH 09Z BEFORE SOME DRIER AIR ALOFT..NOTED AT 700MB...ADVECTS IN FROM THE SOUTHWEST AHEAD OF THE TROUGH AXIS TO APPROACH LATER IN THE DAY SATURDAY. THUS..RAIN IS LIKELY TO TURN TO DRIZZLE FROM WEST TO EAST AFTER 09Z..BUT CATEGORICAL POPS SEEM NECESSARY EVERYWHERE FOR THE BALANCE OF THE NIGHT. WITH A 5000 FOOT WEDGE AIR MASS (PER 00Z KGSO RAOB) LOCKING IN...THE CURRENT FORECAST OF TEMPERATURES IN THE LOW TO MID 40S WILL REMAINING NEARLY STEADY OR RISING SLIGHTLY LOOKS GOOD. -SMITH THE WARM ADVECTION DRIVEN PRECIPITATION SHOULD COME TO AN END FROM WEST TO EAST BY EARLY SATURDAY MORNING. HOWEVER...THE LULL IN PRECIPITATION WILL BE SHORT LIVED AS A COLD FRONT ADVANCES TOWARDS THE AREA DURING THE DAY ON SATURDAY. SOUTHWESTERLY FLOW AHEAD OF THE FRONT WILL PUMP WARM AND MOIST AIR INTO THE REGION...WITH MAX TEMPERATURES EXPECTED TO RISE INTO THE 60S AREAWIDE (MAYBE EVEN PUSHING 70 DEGREES ACROSS THE SOUTHEAST). ALTHOUGH SOME DIURNAL DESTABILIZATION IS EXPECTED TO OCCUR ACROSS THE EASTERN HALF OF THE FORECAST AREA...DEWPOINTS ARE ONLY EXPECTED TO REACH INTO THE LOW TO MID 50S...THUS LIMITING THE AMOUNT OF INSTABILITY. NAM FORECAST SOUNDINGS SHOW AT BEST CAPE VALUES OF LESS THAN 500 J/KG...WHILE THE GFS FORECAST SOUNDINGS SHOW NO INSTABILITY AT ALL. NEVERTHELESS...DECENT SHEAR WILL BE IN PLACE OVER THE REGION AND IF WE ARE ABLE TO REALIZE SOME OF THE INSTABILITY THE NAM INDICATES...AN ISOLATED THUNDERSTORM OR TWO CANNOT BE RULED OUT SATURDAY AFTERNOON. HOWEVER...FOR NOW WILL LEAVE ANY MENTION OF THUNDER OUT OF THE FORECAST DUE TO THE UNCERTAINTY. OVERALL...AFTER THE BRIEF LULL IN PRECIPITATION SATURDAY MORNING...AM EXPECTING A LINE OF SHOWERS TO PROGRESS FROM NORTHWEST TO SOUTHEAST SATURDAY AFTERNOON/EVENING. SUN AND SUN NIGHT: A STRENGTHENING 1030 MILLIBAR PLUS SURFACE COLD AIR HIGH OVER NEW ENGLAND WILL ADVECT COLDER AND DRIER AIR INTO CENTRAL NORTH CAROLINA DURING THE PREDAWN HOURS...AND THIS WILL SET THE STAGE FOR A SHORT LIVED HYBRID DAMMING EVENT ON SUNDAY AS CONTINUED SOUTHWEST FLOW ALOFT WILL SUPPORT WEAK OVERRUNNING ACROSS CENTRAL NORTH CAROLINA AS THE NEXT PACIFIC TROUGH PUSHES EAST INTO THE CENTRAL UNITED STATES. WITH MOIST COLUMN NOT EXTENDING MUCH BEYOND 700 MILLIBAR...LITTLE TO NO ADDITIONAL ACCUMULATIONS ARE EXPECTED WITH PERIODS OF DRIZZLE THROUGHOUT THE DAY...WITH THE POTENTIAL THAT THE NORTHWEST PIEDMONT COULD SEE A BRIEF PERIOD OF FREEZING DRIZZLE EARLY SUNDAY MORNING AS MODEL SOUNDINGS DRIVE SURFACE TEMPERATURES SUNDAY MORNING INTO THE LOWER TO MID 30S WITH WET BULB FREEZING LINE DEPICTED IN THE SAME CLIMATOLOGICALLY FAVORED AREA AS WELL. FURTHERMORE A HANDFUL OF SREF MEMBERS ALSO INDICATE A BRIEF CHANGEOVER OF FREEZING DRIZZLE WITH LITTLE TO NO ACCUMULATION( A COUPLE OF HUNDREDTHS OR LESS). SURFACE WET BULBS ARE EXPECTED TO REBOUND INTO THE MID 30S THROUGH THE MORNING WITH MINIMAL RECOVERY THROUGHOUT THE DAY. AFTER MORNING LOWS IN THE MID TO UPPER 30S NORTH TO MID 40S SOUTH...EXPECT A NET INCREASE OF ONLY 3 TO 5 DEGREES ACROSS THE AREA. STALLED FRONTAL ZONE SOUTH OF THE AREA BEGINS TO RETREAT NORTHWARD AS A WARM FRONT SUNDAY NIGHT...WITH THE SOUTHERN RETURN FLOW OVERTAKING THE SHALLOW COLD AIR DAMMING AIR MASS ALONG THE SOUTHERN AND EASTERN FLANKS...WHILE REMAINING LOCKED IN OVER THE NORTHWEST PIEDMONT REGION. THIS WILL FAVOR NEAR STEADY TEMPERATURES OVERNIGHT ACROSS THE NORTHWEST WITH TEMPERATURES SLIGHTLY RISING ACROSS THE SANDHILLS AND COASTAL COUNTIES. && .SHORT TERM /MONDAY AND MONDAY NIGHT/... AS OF 250 AM SATURDAY... MON AND MON NIGHT: A TRANSITION FROM A FORMIDABLE CAD REGIME -- BY THIS TIME AN IN-SITU ONE OWING TO THE QUICK DEPARTURE OF THE PROGRESSIVE PARENT HIGH -- TO BRIEF WARM SECTOR OVER AT LEAST SIZABLE PORTION OF CENTRAL NC...TO A COLD FRONTAL PASSAGE...WILL ALL OCCUR IN LESS THAN 24 HOURS THIS PERIOD. THE WEDGE IS EXPECTED TO QUICKLY ERODE ALONG THE EDGES WHERE THE CHARACTERISTIC STABILITY AND DEPTH ARE LOWER THROUGH MIDDAY...BUT HOLD STUBBORNLY IN THE HEART OF THE WEDGE OVER THE NW PIEDMONT INTO THE EARLY AFTERNOON HOURS...BEST REPRESENTED BY THE 00Z ECMWF AND NAM/WRF (DESPITE THE NAM/WRF DISCOUNTED SOLUTION OF A MUCH FARTHER NORTHWARD-DISPLACED SURFACE LOW IN SOUTHERN CANADA...AS OPPOSED TO THE CONSENSUS OF OTHER GUIDANCE WHICH HAS THE LOW IN THE UPPER MIDWEST). AS SUCH...TEMPERATURES SHOULD WARM INTO THE UPPER 60S-LOWER 70S IN WAA AND A FEW BINOVC OVER EASTERN NC...INCLUDING THE RAH COASTAL PLAIN...WHILE THE NW PIEDMONT IS APT TO STRUGGLE THROUGH THE 40S FOR MUCH OF THE DAY...AND TOP OUT ONLY IN THE MID-UPPER 50S FOR A COUPLE OF HOURS VERY LATE IN THE AFTERNOON. NWP GUIDANCE INDICATES ONLY A BRIEF PERIOD OF DEEP MOISTENING AND MID LEVEL CAP EROSION IMMEDIATELY AHEAD OF THE FRONT...AND EVEN THEN LAPSE RATES ARE PROJECTED TO REMAIN PSEUDO-MOIST ADIABATIC OWING TO THE PASSAGE OF THE PARENT NEGATIVELY-TILTED S/W TROUGH AND ACCOMPANYING CAA ALOFT TO THE NW OF THE WARM SECTOR OVER CENTRAL AND EASTERN NC. AS SUCH...THUNDER POTENTIAL IS QUITE LOW...AND THE PROBABILITY OF SHOWERS WILL BE HELD IN THE 30-60 PERCENT RANGE...HIGHEST NORTH AND NORTHWEST IN CLOSER PROXIMITY TO BOTH THE S/W TROUGH ALOFT AND THE RETREATING/ERODING WEDGE FRONT. TIMING DIFFERENCES REMAIN WRT THE FRONTAL PASSAGE AND FOLLOWING CAA MON NIGHT...SO ONLY MINOR MODIFICATION TO LOWS IN THE UPPER 30S TO MID-UPPER 40S WAS JUSTIFIED. && .LONG TERM /TUESDAY THROUGH FRIDAY/... AS OF 310 AM SATURDAY... TUE THROUGH FRI: MILD POST-FRONTAL HIGH PRESSURE WILL FOLLOW FOR THE MIDDLE OF THE WEEK...WITH TEMPERATURES RANGING FROM THE UPPER 50S TO MIDDLE 60S FOR HIGHS...WARMEST THU. WHILE NWP GUIDANCE CONTINUES TO INDICATE THE FRONTAL ZONE FORECAST TO CROSS OUR REGION MON NIGHT WILL STALL OVER THE GULF COAST...BUT SOLUTIONS VARY WILDLY WRT TO HOW QUICKLY AND PHASED WITH THE NORTHERN STREAM (IF AT ALL) A SOUTHERN STREAM UPPER LOW WILL PROGRESS EASTWARD AND ACTIVATE THE STALLED FRONTAL ZONE WITH OUR ENSUING NEXT CHANCE OF RAIN. WILL ACCORDINGLY MAINTAIN FORECAST CONTINUITY FROM PREVIOUS SHIFTS...WHICH DEPICTS SLIGHT TO LOW CHANCE PROBABILITIES WED NIGHT ONWARD AND ACCOUNTS FOR THE INHERENT FORECAST UNCERTAINTY. HOWEVER... REALISTICALLY THERE WILL BE ONLY A COUPLE OF RELATIVELY BRIEF BOUTS...ON THE ORDER OF SIX HOURS AT A TIME...OF RAINFALL DURING THE ENTIRE PERIOD - ONE WITH THE NORTHWARD RETREAT OF THE FRONTAL ZONE AHEAD OF THE INEVITABLE SURFACE LOW ATTENDING THE SOUTHERN STREAM...AND ANOTHER WITH THE TRAILING COLD FRONT. && .AVIATION /06Z SATURDAY THROUGH WEDNESDAY/... AS OF 120 AM... MOSTLY LIFR CEILINGS NORTHWEST PIEDMONT WITH IFR TO MVFR ELSEWHERE. MOSTLY MVFR VISIBILITIES IN AREAS OF RAIN. SOME IMPROVEMENT IN CEILINGS AFTER SUNRISE... ESPECIALLY LATE AFTERNOON INTO EARLY EVENING AS CHARACTER OF PRECIPITATION CHANGES FROM RAIN TO SHOWERS. CONDITIONS DETERIORATE IN THE EARLY EVENING TO IFR TO MVFR CEILINGS WITH MVFR VISIBILITIES IN PRECIPITATION. SUB VFR CONDITIONS DOMINATE INTO MONDAY MORNING. THEN VFR INTO WEDNESDAY EVENING. && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ NEAR TERM...SMITH/KRR SHORT TERM...MWS LONG TERM...MWS
AREA FORECAST DISCUSSION FOR SOUTHEAST SD/SOUTHWEST MN/NORTHWEST IA
NWS SIOUX FALLS SD
310 AM CST SAT JAN 21 2012 .DISCUSSION.../ISSUED AT 300 AM CST/ MAIN CONCERN FOR TODAY WILL BE CLOUD COVER AND BLOWING SNOW. STRATUS IS RETURNING NORTH THIS MORNING BETWEEN JAMES AND BIG SIOUX RIVER WITH RETURN LOW LEVEL SELY FLOW. SO WUD EXPECT THIS STRATUS TO CONTINUE TO ADVECT NORTH UNDER LOW LEVEL INVERSION AND RUC SEEMS TO HANDLE THIS LOW LEVEL MOISTURE FAIRLY WELL SO WILL KEEP FAIRLY HIGH CLOUD COVER THOSE AREA THIS MORNING WITH THE INVERSION RISING A BIT BY AFTERNOON WHICH SHOULD HELP SCOUR IT OUT A BIT. NEXT IS THE INCREASING SOUTHERLY WINDS AHEAD OF NEXT WAVE THAT SHOULD GUST TO 30 TO 35 MPH LATER THIS MORNING AND AFTERNOON WHICH SHOULD CREATE AREAS OF BLOWING SNOW. WILL NOT ISSUE ANY ADVISORY AS HARD TO CREATE WIDESPREAD BLOWING PROBLEMS WHEN LOW LEVEL MOISTURE INCREASES OVER FRESH SNOW COVER. SO FOR NOW WILL JUST MENTION AREAS OF BLOWING SNOW THROUGH THE EVENING HOURS. HIGH TEMPERATURES TODAY WILL AGAIN STRUGGLE ACROSS THE EAST BUT SHOULD WARM CLOSER TO NORMAL ACROSS THE WEST. WITH STOUT SOUTHERLY FLOW TONIGHT...NOT EXPECTING TEMPERATURES TO FALL MUCH AND SHOULD ACTUALLY RISE A BIT...ESPECIALLY EAST. SYSTEM COMING OUT LATE TONIGHT AND SUNDAY A BIT SLOWER. STILL CONTINUES TO SHOW A SPLIT FLOW SYSTEM WITH ONE SYSTEM LIFTING UP ACROSS NORTHWEST CWA AND SOUTHERN WAVE MOVING NORTHEAST ACROSS CENTRAL PLAINS AND THEN PHASING EAST OF I29 SUNDAY NIGHT. WITH SLOWER SPEED THERE MAY NOT BE MUCH IF ANY PRECIPITATION ACROSS WESTERN CWA TONIGHT EXCEPT POSSIBLY FAR WESTERN CWA AFTER 09Z. WARM ENOUGH ALOFT THAT ANY PRECIPITATION WOULD BE FREEZING RAIN AND NOT SNOW SO WILL REMOVE MENTION OF SNOW LATE TONIGHT. AMOUNTS IF ANY WILL BE VERY LIGHT AND WILL NOT ISSUE ANY HEADLINE. ON SUNDAY...SOUTHERN WAVE MAY CLIP NORTHWEST IOWA DURING THE AFTERNOON AND WILL KEEP 40% POPS THERE AND LIKELY POPS ACROSS FAR NORTHWEST CWA WITH NORTHERN WAVE. IN BETWEEN WILL KEEP POPS RELATIVELY LOW IN THE 30% RANGE. DOUBT WE WILL SEE ANY FREEZING RAIN BY LATER SUNDAY MORNING AND AFTERNOON AS AIRMASS COOLS AND ANYTHING THAT DOES FALL WILL BE SNOW. SO WILL REMOVE ANY MENTION OF RAIN WEST AND WILL ALSO LOWER HIGH TEMPERATURES DUE TO THE COOLING OF THE COLUMN WITH THESE FEATURES. COULD SEE AN INCH OR TWO OF SNOW IN THE JAMES VALLEY SUNDAY AFTERNOON. GUSTY NORTHWEST WINDS WILL DEVELOP SUNDAY AFTERNOON ACROSS THE WESTERN CWA AS SURFACE TROF MOVES EAST WITH COLD AIR ADVECTION BRINGING IN STRONGER WINDS. SO COULD SEE SOME MORE BLOWING SNOW ACROSS THE WEST. SUNDAY NIGHT WILL SEE GUSTY NORTHWEST WINDS AND AREAS OF BLOWING SNOW WITH SOME LIGHT SNOW ACROSS THE CWA WITH PHASING UPPER TROF. NOT EXPECTING MUCH IN THE WAY OF ACCUMULATIONS WITH LESS THAN ONE INCH EXPECTED. ANOTHER CHILLY DAY ON MONDAY BEHIND THE WAVE WITH BELOW NORMAL TEMPERATURES EAST WITH HIGHS IN THE TEENS TO LOWER 20S. SHOULD BE A BIT WARMER WEST WITH HIGHS IN THE 20S. SURFACE HIGH WILL SETTLE ACROSS THE CWA MONDAY NIGHT...AND WITH LIGHT WINDS AND FRESH SNOW COVER...WITH GO 5 TO 10 DEGREES COLDER THAN CONSALL AND CONSRAW WHICH ARE NOT HANDLING SNOW COVER WELL AS EVIDENT BY THE VERY COLD TEMPERATURES THIS MORNING ACROSS MUCH OF CWA. WOULD NOT BE SUPRISED IF A FEW LOCATIONS ACROSS THE EAST DROP BELOW ZERO EARLY TUESDAY MORNING. SHOULD BE WARMER ACROSS THE CWA TUESDAY THROUGH FRIDAY WITH A MORE ZONAL FLOW...BUT SNOW COVER WILL HAVE A HUGE IMPACT...ESPECIALLY EAST WHERE SNOW COVER IS DEEPER AND WILL NOT MELT OFF. SO MAY AT BEST SEE HIGHS NEAR 30 ACROSS THE EAST DURING THIS TIME PERIOD...WHILE WESTERN CWA WILL HAVE A BETTER CHANCE TO MELT AWAY SOME OF THE SNOW AND APPROACH 40 FOR DAYTIME HIGHS...ESPECIALLY SOUTHWEST CWA. DOESN`T LOOK LIKE MUCH THREAT FOR ANY PRECIPITATION AFTER SUNDAY AND WILL BASICALLY KEEP CWA DRY EXPECT FOR A VERY SLIGHT CHANCE OF LIGHT SNOW TUESDAY NIGHT EAST OF I29 WITH VERY WEAK WAVE. && .AVIATION.../FOR THE 06Z TAF ISSUANCE/ LAST OF MAINLY OVER FAR SOUTHEAST SOUTH DAKOTA SHOULD EXIT OVER FIRST FEW HOURS OF TAF PERIOD. VISIBILITIES ARE MORE TRICKY...WITH POTENTIAL FOR SPOTTY MVFR CONDITIONS THROUGH THE PERIOD. FIRST WILL BE LATE TONIGHT...AS LIGHT WINDS/CLEAR SKIES/FRESH SNOW COVER ALLOW FOR STRONG RADIATIVE COOLING. COULD SEE AREAS OF ICE CRYSTALS DEVELOP IN THE SURFACE RIDGE AXIS...AND HAVE ADDED A FEW HOURS OF MVFR VISIBILITY TO ALL TAFS DURING PERIOD OF CALM WINDS OVERNIGHT. SECOND...INCREASING SOUTHERLY WINDS AFTER 15Z-16Z SATURDAY WITH FREQUENT GUSTS OF 25-30KTS LIKELY...WHICH MAY PRODUCE BLOWING AND DRIFTING OF THE RELATIVELY FLUFFY FRESH SNOWCOVER. BLOWING SNOW COULD RESULT IN AREAS OF MVFR OR EVEN SPOTTY IFR VISIBILITY IN OPEN AREAS DURING THE LATE MORNING/AFTERNOON SATURDAY...AND HAVE MENTION OF MVFR VISIBILITY IN ALL TAFS DURING PERIOD OF EXPECTED STRONGEST WIND GUSTS...WHICH COULD APPROACH 35KTS 19Z-23Z. /JH && .FSD WATCHES/WARNINGS/ADVISORIES... SD...NONE. MN...NONE. IA...NONE. NE...NONE. && $$
AREA FORECAST DISCUSSION
NWS MILWAUKEE/SULLIVAN WI
317 AM CST SAT JAN 21 2012 .TODAY AND TONIGHT...FORECAST CONFIDENCE...MEDIUM NEAR LAKE MICHIGAN THE MAIN ISSUE WILL BE HANDLING LAKE EFFECT TRENDS. NORTHEAST WINDS IN SHALLOW LAYER FROM 975 MB TO 900 MB. LAPSE RATES ARE NOT TO STEEP WITH AROUND 3 C/KM AT MILWAUKEE BUT NEAR 6C/KM NEAR KENOSHA AT 09Z BUT LAPSE RATES INCREASE TO NEAR 9C/KM AT 18Z WITH INVERSION HEIGHT AROUND 3 THSD FT. LOW LEVEL FLOW WEAKENS AND BECOMES MORE EAST. THEREFORE EXPECT THE SNOW BAND NEAR KENOSHA TO CONTINUE TO WEAKEN AND THEN EVENTUALLY BECOME MORE DIFFUSE WITH GENERAL LIGHT SNOW/FLURRIES NEAR THE LAKE. HRRR SHOWS THE LAKE BAND PUSHING SOUTH THEN WEAKENING BUT INCREASING IN COVERAGE. NAM SHOWS SOMETHING SIMILAR. ELSEWHERE MOISTURE TRAPPED BLOW DEVELOPING INVERSION AROUND 3 THSD FT SHOULD SLOW ANY CLEARING FROM THE WEST. FORECAST SOUNDINGS SHOW SOME CLEARING POTENTIAL OVER THE FRINGES OF THE STRATUS SHIELD BUT THEN WITH THE EAST FLOW...LOW LEVELS MOISTEN SO STRATUS/STRATOCUMULUS COULD EXPAND AGAIN. MID LEVEL SHORTWAVE OVER THE EASTERN GREAT LAKES EXITS TO THE EAST WITH MID LEVEL DRYING. STRONG SHORTWAVE OVER THE PACIFIC NORTHWEST WILL REACH THE ROCKIES TONIGHT. LOW/MID LEVEL WARM AIR ADVECTION BEGINS BUT THE 850 TO 700 MB LAYER IS FAIRLY DRY SO NOT EXPECTING ANY PRECIPITATION. BY MIDNIGHT SOUNDINGS SHOW TEMPERATURES AROUND 800 MB ALREADY WARMING ABOVE 0 CELSIUS OVER MUCH OF THE FORECAST AREA...AND ABOVE 0 C BY SUNRISE. NAM SHOWS SATURATION BELOW 925 MB BUT DOES NOT APPEAR DEEP ENOUGH MOIST LAYER FOR FREEZING DRIZZLE. .SUNDAY AND MONDAY...FORECAST CONFIDENCE...MEDIUM MODELS SLOWLY COMING INTO BETTER AGREEMENT FOR THE SUNDAY/MONDAY LOW PRESSURE SYSTEM. THE GFS HAS TRENDED TOWARD THE SLOWER ECMWF AND CANADIAN SOLUTIONS...WHILE THE NAM REMAINS THE QUICKEST. LEANED FORECAST PRETTY HEAVILY TOWARD CONSISTENT ECMWF. OVERALL...LOOKS LIKE A CHANCE FOR WARM ADVECTION PRECIP ON SUNDAY. MID LEVELS ARE QUITE DRY IN SOUNDINGS...WITH VERY LITTLE ICE EXPECTED. WITH SFC TEMPS BELOW FREEZING TO START THE DAY...KEPT MENTION OF FREEZING RAIN. MENTIONED RAIN A CHANCE FOR RAIN AS WELL IN THE AFTERNOON AS TEMPS WARM ABOVE FREEZING. ONLY REASON SNOW WAS LEFT IN FOR SUNDAY IS THAT SOME MODELS DO SHOW SOME ICE CRYSTAL POTENTIAL ABOVE THE DRY LAYER. DRY LAYER LOOKS LIKE IT WILL GENERALLY DRY UP ANY ICE...BUT POTENTIAL FOR SEEDING IS THERE IF DRY LAYER IS OVERDONE IN MODELS. PRECIP AMOUNTS EXPECTED TO BE LIGHT DURING THE DAY SUNDAY...SO ANY ICING WOULD BE FAIRLY LIMITED. SFC LOW EXPECTED TO MOVE THROUGH SUNDAY NIGHT...ALONG WITH BEST SHOT FOR PRECIP FROM THIS STORM. ENOUGH OVERLAP BETWEEN MODELS TO BUMP POPS UP TO CATEGORICAL. LOOKS LIKE MAINLY RAIN EAST...MIXING WITH SNOW WEST. MAY SEE EVENTUAL CHANGE OVER TO SNOW WEST TO EAST BEGINNING LATE SUNDAY NIGHT OR MONDAY MORNING...WITH SOME LIGHT ACCUMULATIONS POSSIBLE. WITH DEWPOINTS EXPECTED TO GET INTO THE MID 30S OVER THE SNOWPACK...AND THE SFC LOW COMING RIGHT OVERHEAD...MENTIONED PATCHY FOG IN THE EAST SUN NIGHT AND MON MORNING. .TUESDAY THROUGH FRIDAY...FORECAST CONFIDENCE...MEDIUM LOOKS FAIRLY QUIET TUESDAY THROUGH THE REMAINDER OF THE WORK WEEK. MODELS DEPICTING A SERIES OF WEAK SHORTWAVES TO ROLL THROUGH DURING THIS PERIOD...POSSIBLY BRINGING SOME FLURRIES OR LIGHT SNOW AT TIMES. NEAR NORMAL TEMPS TUESDAY EXPECTED TO WARM TO A FEW DEGREES ABOVE NORMAL FOR WEDNESDAY THROUGH FRIDAY. && .AVIATION/12Z TAFS/... MAINLY MVFR CIGS OVER FAR SOUTH CENTRAL AND PORTIONS OF SOUTHEAST WISCONSIN. LAKE BAND PUSHING SOUTH BUT STRONGEST RADAR RETURNS HAVE BEEN STAYING OFF SHORE. AS LOW LEVEL FLOW BECOMES MORE EAST LAKE EFFECT WILL EXPAND IN COVERAGE BUT SHOULD BE FAIRLY LIGHT...ALTHOUGH SOME AREAS COULD SEE SOME VERY LIGHT ACCUMULATIONS. CIGS/VSBYS WILL BE MAINLY MVFR. THE LOW CLOUD SHIELD MAY ERODE SOMEWHAT FROM THE WEST...BUT THEN WOULD TEND TO EXPAND AGAIN AS EAST FLOW INCREASES THE LOW LEVEL MOISTURE. IFR POTENTIAL LATER TONIGHT AS EAST/SOUTHEAST FLOW INCREASES. && .MARINE... A SMALL CRAFT ADVISORY WILL LIKELY BE NEEDED LATE TONIGHT THROUGH MONDAY NIGHT AS LOW PRESSURE MOVES EAST AND EXITS THE NORTHERN PLAINS. BRISK SOUTH WINDS AND HIGH WAVES WILL PREVAIL SATURDAY NIGHT INTO SUNDAY NIGHT. A COLD FRONT WILL THEN SHIFT THE WINDS TO THE WEST FOR LATE SUNDAY NIGHT AND INTO MONDAY NIGHT. THE WINDS WILL CONTINUE TO BE BRISK AND GUSTY AND SMALL CRAFT CONDITIONS WILL LIKELY PERSIST FOR THIS TIME PERIOD. && .MKX WATCHES/WARNINGS/ADVISORIES... WI...NONE. LM...NONE. && $$ TODAY/TONIGHT AND AVIATION/MARINE...HENTZ SUNDAY THROUGH FRIDAY...DDV
AREA FORECAST DISCUSSION...UPDATED
NWS MILWAUKEE/SULLIVAN WI
1042 PM CST FRI JAN 20 2012 .UPDATE... LAKE EFFECT SNOW BAND HAS NOT SHIFTED SOUTH YET AND IN FACT IS DRIFTING NORTH. ADDED MILWAUKEE COUNTY BUT EXPECT BAND TO STAY SOUTH OF THE CITY OF MILWAUKEE. LOOKS LIKE SNOWFALL RATES PER KMKX DOPPLER RADAR ARE ON THE ORDER OF 0.50" PER HOUR. LATEST HRRR HAS BAND STARTING TO SHIFT SOUTH IN ABOUT 5 HOURS SO COULD END UP WITH 3-4 INCHES NEAR SOUTH MILWAUKEE AND OAK CREEK BEFORE IT DOES SO. NATURALLY WITH LAKE EFFECT UNCERTAINTY IS ALWAYS PRETTY HIGH AND THE LATEST GUIDANCE ALL HAS A GENERAL HANDLE ON THE LOCATION AND TIMING BUT EACH IS ABOUT A COUNTY OFF. MOST OF THE CURRENT GUIDANCE SUGGESTS THAT THE BAND SHOULD BE OFFSHORE. 00Z NAM HOLDS THE BAND IN MILWAUKEE COUNTY FOR A WHILE BEFORE SHIFTING SOUTH. SINCE HRRR AND LOCAL 4KM RUN ARE SIMILAR...WILL GO WITH THAT SCENARIO FOR NOW. AT THIS POINT KENOSHA COUNTY ADVISORY MAY BE OVERDONE BUT THE BAND SEEMS LIKELY TO SHIFT SOUTH EVENTUALLY AND KMKE TDWR HAS SHOWN FLOW AT 925 MB GRADUALLY BACK TO MORE NORTHERLY WITH TIME. && .MKX WATCHES/WARNINGS/ADVISORIES... WI...LAKE EFFECT SNOW ADVISORY UNTIL 6 AM CST SATURDAY FOR WIZ066-071- 072. LM...NONE. && $$ UPDATE...CRAVEN
AREA FORECAST DISCUSSION
NWS ALBANY NY
1000 AM EST SAT JAN 21 2012 .SYNOPSIS... WEAK LOW PRESSURE WILL TRACK OFF THE NEW JERSEY COAST TODAY AND BRING SNOW TO THE AREA. A HIGH PRESSURE SYSTEM WILL BUILD INTO THE NORTHEAST TONIGHT AND SUNDAY BRINGING FAIR WEATHER. ON MONDAY...A POWERFUL STORM MOVES FROM THE UPPER GREAT LAKES INTO WESTERN QUEBEC...LIKELY BRINGING MIXED PRECIPITATION CHANGING TO RAIN. && .NEAR TERM /THROUGH TONIGHT/... WEAK MIDLEVEL SYSTEM MOVING FROM WEST TO EAST. SNOW HAS ENDED OR GREATLY DIMINISHED OVER NORTHWEST PART OF AREA. LATEST RUC ANALYSIS SHOWS H850 WARM ADVECTION CONTINUING ACROSS THE AREA AND VAD WIND PROFILE CONFIRMS THIS. SNOW SEEMS TO BE ENDING ONCE MID/HIGH LEVEL CLOUDS MOVE AWAY AND SEEDER FEEDER MECHANISM DIMINISHES. CLOUD TOPS COOLING OVER SOUTHEAST PART OF FORECAST AREA INDICATING ONE MORE BAND OF MODERATE SNOW POSSIBLE THERE LATE THIS MORNING BEFORE HIGHER CLOUDS MOVE OFF AND SNOW DIMINISHES. RECENT UPDATE TO ADJUST POPS WHERE SNOW HAS DIMINISHED OR ENDED. ALSO ADJUSTED MAX TEMPS DOWNWARD 2 DEGREES VALLEYS AND 3-5 DEGREES MOUNTAINS AS OBS SHOW TEMPS NOT MOVING THIS MORNING. PREVIOUS... CURRENTLY -SN HAS OVER SPREAD MOST OF NY FCA EXCPT N ADIRONDACKS AND W NEW ENG...WHERE SNOW WILL BEGIN SHORTLY. OTHER THAN SOME MINOR ADJUSTMENTS TO POPS/WX FCST REMAINS ON TRACK. SURFACE WAVE MOVES FROM TN VLY TO NJ COAST TODAY. ISENTROPIC LIFT IS MAIN MECHANISM PRODUCING UVM FOR SNOW TODAY. ALTHOUGH 500HPA TROF AND ITS VORT MAX PASSING ACROSS US/CAN BORDER RGN SUPPORT SOME UVM IN N PTNS OF FCA. OVERALL SNOW WILL BE GENERALLY LIGHT ON ORDER OF 1-3 INCHES...EXCEPT IN SOUTHERN MOST AREAS WHERE MODERATE AMOUNTS ARE EXPECTED (3-6IN) CLOSEST TO THE BEST ISENTROPIC LIFT AND UVM. MODELS (GEM/NAM/GFS/ECMWF) IN GOOD AGREEMENT FOR THIS PERIOD. QPF A BLEND OF CURRENT FCST...HPC AND ALL 00UTC MODELS. GIVEN CONTRAST ACROSS THERMAL RIBBON USED SNOW/LIQ RATIO OF 13. AS OF 230AM -SN HAS REACHED A RME-BGM LINE. THIS WILL CONTINUE TO ADVANCE REACHING HUD VLY BY 5-6AM. SNOW WILL PERSIST INTO THE EARLY AFTN THEN END RAPIDLY FM NW TO SE AS 500HPA TROF AND SFC LOW MOVES OFFSHORE CUTTING OFF ISENTROPIC LIFT. OVERNIGHT 500HPA RIDGE BUILDS INTO NE USA..AND SFC HIGH BUILDS OVER NEW ENG AND NY IN RESPONSE TO DIF ACVA. SKIES WILL CLEAR DURING THE LATE AFTN AND ERLY EVENING...WITH CLR CONDS AND FRESH SNOW IN MOST AREAS. SHOULD ALLOW FOR GOOD RAD COOLING AND TEMPS TO PLUNGE TO NR NORMAL. WINDS SHOULD BE LIGHT NE DURING THIS PERIOD EXCEPT ARND 10KTS IN S PTNS OF FCA. && .SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/... WE BEGIN THIS SHORT TERM PORTION OF THE FORECAST ON A TRANQUIL NOTE WITH A 1035MB SURFACE HIGH SLIDING ACROSS THE EASTERN GREAT LAKES REGIONS AND NEW ENGLAND THROUGH THE DAY. FAIRLY DRY BELOW 500MB TO KEEP POPS AT ZERO AND SKIES PT-MOSUNNY. TEMPERATURES WILL BE SEASONABLE FOR THIS TIME OF THE YEAR WITH MAINLY 20S FOR THE TERRAIN AND LOWER 30S FOR THE VALLEY FLOOR. MEANWHILE...A POWERFUL SHORT WAVE COINCIDING WITH 150KT UPPER LEVEL JET WAS COMING ASHORE ACROSS CALIFORNIA. THIS SYSTEM IS FORECAST BY THE NCEP MODEL SUITE TO IMPACT THE 4-CORNERS REGION AND EJECT OUT ONTO THE CENTRAL-SOUTHERN PLAINS SUNDAY INTO MONDAY. A POWERFUL SURFACE CYCLONE WILL DEVELOP OVER THE MID-LOWER MISSISSIPPI RIVER VALLEY AND TRACK INTO THE CENTRAL GREAT LAKES REGION THROUGH MONDAY. THE MAIN IMPACT FOR OUR REGION WILL BE AN INCREASE IN CLOUD COVER AND A STRENGTHEN SOUTHERLY WIND. HOWEVER...ISSUES ARISE OVERNIGHT SUNDAY INTO MONDAY MORNING FOR THE REGION. A CLOSER EXAMINATION OF BUFKIT AND HOURLY BUFR PROFILES FROM THE MODEL SUITES THIS MORNING ALL SUGGEST A RAPID INCREASE IN LOWER LEVEL MOISTURE FROM SOUTH TO NORTH. COMBINE THAT WITH THE WIND MAGNITUDE INCREASE AND LOW LEVEL SHEAR FOR DRIZZLE FORMATION SINCE ICE NUCLEI IS NOT EXPECTED IN THE COLUMN WITH THE HEIGHT OF THE MOISTURE PROFILES STAYING BELOW THE -10C THROUGH AT LEAST 15Z MONDAY. DUE TO SEASONABLE TEMPERATURES EXPECTED ON SUNDAY...AND SOME PARTIAL CLEAR SKIES SUNDAY EVENING...OVERNIGHT SURFACE TEMPERATURES ARE EXPECTED TO DROP BACK INTO THE TEENS ACROSS THE DACKS AND LOW-MID 20S ELSEWHERE. THIS SEEMS TO SUGGEST THAT ANY DRIZZLE FORMATION WILL FREEZE ON CONTACT. TEMPERATURES ARE EXPECTED TO CLIMB ABOVE FREEZING ALONG THE HEELS OF THE STRENGTHEN SOUTHERLY FLOW BY NOON MONDAY WHERE WE WILL REMOVE THE MENTION OF FROZEN DRIZZLE/RAIN. MONDAY AFTERNOON...AN INCREASE IN LOW LEVEL WARM ADVECTION ALONG WITH THE APPROACH OF THE FRONTAL BOUNDARY WILL KEEP POPS QUITE HIGH FOR PERIODS OF RAIN/SHOWERS. THERE ARE SOME SUBTLE HINTS THAT THUNDER COULD BE A POSSIBILITY SOUTH OF THE CAPITAL REGION WITH SHOWALTER INDICES DROPPING BACK TO NEAR 1C AND SLIGHTLY FAVORABLE MID LEVEL LAPSE RATES. WE WILL CONTINUE TO MONITOR AND NOT MENTION IN THE FORECAST/GRIDS. HIGH TEMPERATURES COULD EXCEED 40F FOR THE MAJORITY OF THE REGION. THE FRONT AND ASSOCIATED MOISTURE TRACK QUICKLY TO OUR NORTHEAST WITH A DECREASE IN POPS. HOWEVER...WITH A NEAR VERTICALLY STACKED LOW OVER THE GREAT LAKES REGION AND COLD ADVECTION...LAKE ONTARIO CONTRIBUTION IS EXPECTED TO INCREASE. DELTA T/S ARE ONLY EXPECTED TO REMAIN MARGINAL SO WE WILL KEEP POPS FOR PORTIONS OF THE DACKS IN THE 30% THRESHOLDS FOR SNOW SHOWERS. && .LONG TERM /TUESDAY THROUGH FRIDAY/... THE AFOREMENTIONED LAKE EFFECT ACTIVITY COULD STILL BE IMPACTING PORTIONS OF THE DACKS WITH A WEST-SOUTHWEST BOUNDARY LAYER WINDS AROUND THE PERIPHERY OF THE SLOWLY DEPARTING UPPER LOW. OTHERWISE...BUILDING SURFACE PRESSURES ARE EXPECTED TUESDAY THROUGH WEDNESDAY. A WEAK MID LEVEL IMPULSE APPROACHES LATE WEDNESDAY AS THE MAIN IMPACT SHOULD BE FROM AN INCREASE IN HIGH- MID LEVEL MOISTURE. THURSDAY THRU FRIDAY...CONSIDERABLE UNCERTAINTY REMAINS AS THE GFS REMAINS THE MOST PROGRESSIVE AND THE ECMWF A BIT MORE PRONOUNCED WITH RESPECT TO APPALACHIANS STORM SYSTEM THAT COULD IMPACT THE REGION THURSDAY NIGHT INTO FRIDAY. ENSEMBLES FROM THE GFS OFFER A WIDE VARIETY OF SOLUTIONS WITH A FEW CLUSTERS EVEN STRONGER THAN THE ECMWF AND FURTHER WEST. FOR NOW...A LOW CONFIDENCE FORECAST FOR THE END OF THIS WEEK. && .AVIATION /12Z SATURDAY THROUGH WEDNESDAY/... MVFR CIGS/VSBY IN -SN EXIST OVER MOST OF FCA. OVER NEXT FEW HRS MOST AREAS FM ADIRONDACKS SOUTH WILL LOWER TO MVFR/IFR CIGS AND VSBY IN -SN. IFR CONDS WILL BE MORE WIDESPREAD SOUTH. CONDS WILL IMPV DURING THE AFTN BCMG MVFR FM NW TO SE...AND VFR BY EVENING. WINDS WILL BE NORTH-NORTHEAST AROUND 5-10 KT TODAY. OUTLOOK... SAT NIGHT-SUN...VFR. NO SIG WX. SUN NIGHT-MON MRNG...BCMG MVFR/IFR LATE. CHC -RA/-SN/-PL/-FZRA. MON AFTN...MVFR/IFR. RA LIKELY. MON NIGHT-TUE...VFR. SLIGHT CHC -SHRASN AND MVFR. TUE NIGHT-WED...VFR. NO SIG WX. && .HYDROLOGY... NO MAJOR PROBLEMS ARE EXPECTED ON THE MAIN STEM RIVERS THROUGH NEXT FRIDAY. ANY PRECIPITATION WHICH FALLS THROUGH THIS WEEKEND WILL BE SNOW. MONDAY MAY BRING SOME LIGHT MIXED PRECIPITATION EARLY AND 0.25" TO 0.50" OF RAIN DURING THE AFTERNOON. ICE FORMATION ON BODIES OF WATER IS EXPECTED TO INCREASE AGAIN THROUGH THE WEEKEND AS COLD AIR WILL BE IN PLACE ACROSS THE REGION. TEMPS WILL BEGIN RISING LATE SUNDAY AND MONDAY...ONLY COOLING TO NEAR OR SLIGHTLY ABOVE NORMAL NEXT WEEK. FOR DETAILS ON SPECIFIC AREA RIVERS AND LAKES...INCLUDING OBSERVED AND FORECAST RIVER STAGES AND LAKE ELEVATIONS...PLEASE VISIT THE ADVANCED HYDROLOGIC PREDICTION SERVICE /AHPS/ GRAPHS ON OUR WEBSITE. && .ALY WATCHES/WARNINGS/ADVISORIES... CT...WINTER WEATHER ADVISORY UNTIL 3 PM EST THIS AFTERNOON FOR CTZ001-013. NY...WINTER WEATHER ADVISORY UNTIL 3 PM EST THIS AFTERNOON FOR NYZ063>066. MA...NONE. VT...NONE. && $$ SYNOPSIS...SNYDER/SND NEAR TERM...SNYDER/SND SHORT TERM...BGM LONG TERM...BGM AVIATION...SNYDER HYDROLOGY...BGM
AREA FORECAST DISCUSSION
NWS COLUMBIA SC
938 AM EST SAT JAN 21 2012 .SYNOPSIS... A MOIST SOUTH FLOW WILL OCCUR AHEAD OF AN APPROACHING COLD FRONT. THE FRONT WILL MOVE THROUGH THE FORECAST AREA TODAY AND BE STALLED JUST SOUTH OF THE AREA SUNDAY. ANOTHER COLD FRONT WILL MOVE THROUGH THE AREA MONDAY. DRYING BEHIND THIS FRONT WILL DOMINATE TUESDAY. && .NEAR TERM /UNTIL 8 PM THIS EVENING/... MOISTURE WILL BE ON THE INCREASE IN THE SOUTH FLOW AHEAD OF THE COLD FRONT. A MID-LEVEL SHORTWAVE TROUGH WILL ALSO BRING AN INCREASE IN MOISTURE AND INSTABILITY. BELIEVE SHOWER COVERAGE WILL INCREASE. THIS MORNING/S 88D VAD WIND PROFILE INDICATED WINDS OF 50 KNOTS AT 3000 FEET. THE LATEST RUC SHOWS THE SHEAR CONTINUING DURING THE AFTERNOON. ENOUGH INSTABILITY MAY DEVELOP FOR SEVERE THUNDERSTORMS. THE NAM SHOWS SURFACE-BASED LI/S LOWERING TO AROUND -2. THE THREAT TIMING APPEARS TO BE MAINLY BETWEEN 200 PM AND 800 PM BASED ON THE LATEST RUC MOISTURE CONVERGENCE PATTERN AND H85 JET. THE SHEAR APPEARS UNI-DIRECTIONAL SUPPORTING MAINLY A STRAIGHT-LINE WIND THREAT...EXCEPT THERE COULD POSSIBLY BE MORE DIRECTIONAL SHEAR ALONG A LINGERING BOUNDARY IN THE NORTH PART OF THE FORECAST AREA. REPORTS UPSTREAM ALSO SUPPORT A HAIL THREAT. && .SHORT TERM /8 PM THIS EVENING THROUGH SUNDAY NIGHT/... THE COLD FRONT WILL MOVE THROUGH THE FORECAST AREA TONIGHT. MOISTURE WILL BECOME SHALLOW BEHIND THE FRONT ON SUNDAY...BUT ISENTROPIC LIFT MAY LEAD TO AREAS OF RAIN. MODELS CONTINUE TO INDICATE THAT A LOW-LEVEL WEDGE PATTERN WILL SETUP SUNDAY AND SUNDAY NIGHT. WITH SOME ISENTROPIC FLOW OVER THE WEDGE POSSIBLE...CAN EXPECT TO HAVE SOME LIGHT RAIN AND DRIZZLE THROUGHOUT THE DAY SUNDAY. THE TEMPERATURE GUIDANCE REMAINS TOO WARM SUNDAY BECAUSE OF THE EXPECTED WEDGE PATTERN...AND THUS CONTINUE TO UNDERCUT THE NUMBERS. THE GFS SHOWED THE WEDGE FRONT TRYING TO LIFT NORTH OF THE FORECAST AREA SUNDAY NIGHT. WEDGES SEEM TO STICK AROUND A LITTLE LONGER THAN WHAT MODELS TYPICALLY FORECAST...SO WOULD EXPECT THE WEDGE TO REMAIN SUNDAY NIGHT INTO MONDAY MORNING. EXPECTING A CHANCE OF SHOWERS AND SOME POSSIBLE DRIZZLE SUNDAY NIGHT. && .LONG TERM /MONDAY THROUGH FRIDAY/... ONLY MINOR CHANGES MADE TO THE LONG TERM THIS PACKAGE. ON MONDAY THE WEDGE SHOULD ERODE IN ADVANCE OF THE NEXT APPROACHING COLD FRONT. FORECASTED A CHANCE OF SHOWERS ASSOCIATED WITH THIS FRONT. DRYING BEHIND THE FRONT APPEARED TO DOMINATE TUESDAY INTO WEDNESDAY. KEPT A SMALL POP IN THE FORECAST BECAUSE OF TIMING UNCERTAINTY ASSOCIATED WITH THE WARM ADVECTION PATTERN AHEAD OF THE NEXT SYSTEM. THE GFS ENSEMBLES HAVE SHOWN A HIGH SPREAD IN THE FAST FLOW. KEPT CHANCE POPS DURING THE REST OF THE EXTENDED PERIOD. THE GFS SHOWED THE APPROACHING COLD FRONT REACHING THE FORECAST AREA FRIDAY. && .AVIATION /15Z SATURDAY THROUGH WEDNESDAY/... WARM FRONT MOVING NORTHWARD ACROSS THE CENTRAL SC MIDLANDS EARLY THIS MORNING. ISENTROPIC LIFT OVER REGION LEADING TO LIGHT RAIN OR LIGHT SHOWERS ACROSS THE REGION. SOME BRIEF MVFR CONDITIONS POSSIBLE IN HEAVIER SHOWERS BEFORE 14Z THIS MORNING. AS THE WARM FRONT CONTINUES TO MOVE NORTHWARD...LOW LEVEL WINDS INCREASE 1-2 KFT TO 220 AT 40 KNOTS AND LOW LEVEL WIND SHEAR IS POSSIBLE FROM 12Z-14Z EARLY THIS MORNING. COMPOSITE REGIONAL RADAR INDICATING MORE SHOWERS DEVELOPING OVER NORTHERN GA WHICH WILL MOVE INTO SC LATER THIS MORNING. AFTER AROUND 18Z...WARM AIR ADVECTION IS EXPECTED TO ALLOW STRONGER WINDS TO REACH THE SURFACE WITH GUSTY SOUTHWEST WINDS 15-25 KNOTS THUS DECREASING THE EFFECTIVE WIND SHEAR BUT INCREASING THE POSSIBILITY OF LOW LEVEL TURBULENCE. SOME IFR-MVFR CONDITIONS ARE POSSIBLE LATER DURING THE AFTERNOON AS A COLD FRONT APPROACHES AND THE CHANCES FOR TSTMS INCREASE. A LINE OF THUNDERSTORMS OR POSSIBLY A SQUALL LINE MAY DEVELOP BY LATE AFTERNOON/EARLY EVENING. SPC HAS CAE FA OUTLOOKED FOR A SLIGHT RISK OF SEVERE STORMS TODAY WITH THE MAIN THREAT BEING DAMAGING WINDS. CONVECTIVE ACTIVITY SHOULD DIMINISH DURING THE EVENING HOURS. WINDS WILL BECOME MORE VARIABLE AFTER 06Z SUNDAY AS THE COLD FRONT MOVES EAST OF OUR AREA AND HIGH PRESSURE BEGINS TO BUILD IN FROM THE NORTH. MAINLY MVFR CONDITIONS EXPECTED AFTER 06Z AS DRIZZLE ALONG WITH SOME PATCHY FOG DEVELOP AFTER 06Z SUNDAY. CANNOT RULE OUT SOME IFR CONDITIONS AFTER 06Z BUT CONFIDENCE IS LOW TO MENTION AT THIS TIME. EXTENDED AVIATION OUTLOOK...FRONT TO SLOWLY PASS EARLY SUNDAY MORNING...WITH APPEARANCE OF WEAK WEDGE BUILDING DOWN BEHIND IT ON SUNDAY. THIS WILL PROVIDE POTENTIAL FOR LOW CLOUDINESS...POSSIBLY IFR...EARLY SUNDAY MORNING...INTO SUNDAY NIGHT. THE NEXT FRONT WILL MOVE THROUGH MONDAY PROVIDING A CHANCE OF SHOWERS...AND ASSOCIATED RESTRICTIONS. NO SIGNIFICANT IMPACTS TO AVIATION ARE EXPECTED LATE MONDAY INTO WEDNESDAY...AS HIGH PRESSURE BUILDS IN. && .CAE WATCHES/WARNINGS/ADVISORIES... SC...NONE. GA...NONE. && $$
AREA FORECAST DISCUSSION
NWS LINCOLN IL
556 AM CST SAT JAN 21 2012 .DISCUSSION... ISSUED 330 AM CST SAT JAN 21 2012 WILL ALLOW THE WINTER WEATHER ADVISORY EXPIRE BY 4 AM SE OF LINCOLN. MIXED PRECIPITATION HAS PASSED SE OF IL WITH 1008 MB LOW PRESSURE OVER EASTERN KY. FORECAST CONCERN IS IF ANY CLEARING OCCURS THIS AFTERNOON. THEN LOOKING AS A FAIRLY STRONG WX SYSTEM TO IMPACT THE REGION SUNDAY NIGHT WITH SPC HAVE SLIGHT RISK NEAR SOUTHERN PARTS OF RICHLAND AND LAWRENCE COUNTIES. NCEP FAVORED THE 00Z GFS MODEL WITH THIS WEATHER SYSTEM WITH ABOVE AVERAGE CONFIDENCE AND WILL FOLLOW SUITE. LEANED TOWARD THE 00Z ECMWF MODEL WITH MID/LATE WEEK SYSTEM NEXT WEEK WITH SPLIT UPPER LEVEL FLOW PREVAILING THEN. SHORT TERM...TODAY THROUGH TUESDAY NIGHT TRENDED CLOUDIER AND COOLER TODAY WITH FORECAST DUE TO EXTENSIVE LOW CLOUD COVER ACROSS IL...MO INTO SE HALF OF IA AND LOW LEVEL MOISTURE TRAPPED IN AN INVERSION. COULD BE A FEW PATCHES OF LIGHT FREEZING DRIZZLE INTO MID MORNING OVER CENTRAL IL THOUGH HAVE NOT SCENE ANY REPORTED NEARBY PAST FEW HOURS. TEMPS CURRENTLY RANGE FROM THE MID TEENS FROM PEORIA NW TO THE MID 20S SE OF I-70. NORTH WINDS 8 TO 16 MPH. 1027 MB HIGH PRESSURE OVER THE UPPER MS VALLEY NEAR THE WI/IA/MN BORDER TO DRIFT EAST ACROSS LOWER MI THIS AFTERNOON AND RIDGING INTO IL. THIS TO DECREASE LOW CLOUDS OVER NORTHERN AREAS WHERE SKIES BECOME PARTLY SUNNY...WHILE SE IL STAYS IN THE LOW CLOUDS TODAY. HIGHS MOSTLY IN THE 20S TODAY OVER CENTRAL IL AND LOWER 30S IN SE IL. SOUTHERLY FLOW TO SET UP TONIGHT AS HIGH PRESSURE STRENGTHENS TO 1033 MB AS IT MOVES INTO NEW ENGLAND AND MID ATLANTIC STATES BY DAWN SUNDAY. LOWS PROBABLY REACHED THIS EVENING THEN MAY SNEAK UP A FEW DEGREES OVERNIGHT AS LOW CLOUDS SPREAD BACK TO THE NORTH. A FAIRLY STRONG STORM SYSTEM MOVING EAST INTO THE ROCKIES WILL HAVE A DEEPENING STRONG LOW PRESSURE MOVING INTO THE UPPER MIDWEST SUNDAY NIGHT AND SWEEP A COLD FRONT EAST THROUGH IL SUNDAY EVENING. MILDER HIGHS IN THE 40S SUNDAY WITH LOWER 50S IN SE IL. HAVE SLIGHT CHANCE OF SHOWERS SUNDAY AFTERNOON...EXCEPT 30% CHANCE NW OF THE IL RIVER. LIKELY CHANCES OF SHOWERS SUNDAY NIGHT AND EVEN THUNDERSTORMS FROM I-55 EAST SUNDAY EVENING. WILL NEED TO WATCH SE IL WITH SLIGHT RISK INTO SOUTHERN PARTS OF RICHLAND AND LAWRENCE COUNTIES SUNDAY EVENING. VERY STRONG UPPER LEVEL DYNAMICS AND WIND FIELDS AND DEEP MOISTURE WITH STORM. TEMPS COULD RISE A BIT AHEAD OF THE COLD FRONT SUNDAY EVENING THEN FALL OVERNIGHT INTO MON MORNING. MODELS HAVE TRENDED FURTHER NE WITH LIGHT MIXED PRECIPITATION MONDAY WITH 1025 MB HIGH PRESSURE MOVING INTO THE TN VALLEY BY SUNSET MONDAY AND HAVE ADJUST FORECAST ACCORDINGLY. FAIR WEATHER EXPECTED MONDAY NIGHT THROUGH TUE NIGHT WITH NEARBY HIGH PRESSURE. LONG TERM...WEDNESDAY THROUGH FRIDAY NIGHT EXTENDED MODELS SHOW A SPLIT UPPER LEVEL FLOW DURING MID AND LATE WEEK OF NEXT WEEK AND HAVE TRENDED DRIER ON WED. STRONGER SOUTHERN STREAM SYSTEM WITH CUTOFF LOW OVER NORTHERN MEXICO INTO TX WED-THU KEEPS MOST OF ITS HEAVIER PRECIP SOUTH CENTRAL IL WHILE WEAKER NORTHERN STREAM SHORT WAVE MOVES EAST ACROSS THE NORTHERN TIER STATES. BEST CHANCE OF LIGHT PRECIPITATION APPEARS TO BE OVER SE IL WED NIGHT AND SHOULD BE WARM ENOUGH FOR RAIN THERE. BEST CHANCES OF PRECIPITATION APPEARS TO SHIFT EAST OF IL LATE NEXT WEEK AND TRENDED TOWARD A DRIER FORECAST. GFS AND ECMWF MODEL BOTH HAVE TRENDED DRIER DURING THIS TIME. TEMPS TO STAY ABOVE NORMAL DURING THIS TIME FRAME. HUETTL && .AVIATION... ISSUED 556 AM CST SAT JAN 21 2012...FOR THE 12Z TAFS IFR STRATUS WILL CONTINUE THROUGH MID MORNING...WHEN THE CLOUD LAYER SHOULD LIFT TO MVFR. PIREPS ARE SHOWING THE CLOUD LAYER AS ABOUT 2K FT THICK...SO SOME CLEARING MAY DEVELOP AS MIXING DEEPENS INTO THE DRY LAYER ABOVE 3K FT. THE NORTHWEST EDGE OF THE STRATUS IS NOT PROGRESSING TO THE ESE AS YOU MIGHT EXPECT BEHIND A LOW PRESSURE SYSTEM. SO CLEARING IS A TOUGH CALL. RUC AND HRRR MODELS ARE SHOWING SOME DRYING WORKING INTO OUR AREA FROM THE NORTHEAST...AS SURFACE WINDS INCREASE FROM THE NORTHEAST. SO CMI AND DEC MAY BE THE EARLY TERMINAL SITES TO CLEAR OUT TO VFR THIS AFTERNOON. PIA/BMI/SPI MAY BE DELAYED BY A FEW HOURS TO 20-21Z. NOT HIGHLY CONFIDENT ON THE CLEARING SCENARIO...BUT WILL INCLUDE SOME VFR FROM LATE AFTERNOON THROUGH MID EVENING...WHEN MVFR CLOUDS RETURN ON SOUTHEAST WINDS. WILL KEEP WINDS IN THE 9-13KT RANGE FOR MOST OF THE NEXT 24 HOURS. SOUTHEAST WIND SPEEDS WILL INCREASE TONIGHT AS THE PRESSURE GRADIENT TIGHTENS AHEAD OF THE NEXT WEATHER SYSTEM. SHIMON && .ILX WATCHES/WARNINGS/ADVISORIES... NONE. && $$
AREA FORECAST DISCUSSION
NWS TOPEKA KS
559 AM CST SAT JAN 21 2012 ...UPDATE TO AVIATION... .DISCUSSION... WEAK UPPER TROF WAS EXITING EASTERN KANSAS EARLY THIS MORNING WHILE MUCH STRONGER WAVE WAS APPROACHING THE WEST COAST PER WATER VAPOR IMAGERY. SURFACE RIDGE AXIS REMAINS ACROSS CENTRAL KANSAS..WITH WIDESPREAD STRATUS OOZING SOUTHWEST JUST AHEAD OF IT INTO EAST CENTRAL KANSAS...AND MORE SCATTERED LOW CLOUD TO ITS NORTHWEST IN NORTH CENTRAL KANSAS AND EASTERN NEBRASKA. STRONG PRESSURE FALLS WERE OCCURRING IN THE NORTHERN HIGH PLAINS UNDER QUICK ZONAL FLOW ALOFT. LATEST RUC SEEMS TO BE DOING FAIRLY WELL WITH LOW CLOUD TRENDS...AND SEEMS REASONABLE WITH STRATUS CONTINUING SOUTHWEST THROUGH EAST CENTRAL KANSAS...BUT MAKING LITTLE PROGRESS ELSEWHERE. SHOULD SEE MOSTLY CLEAR SKIES TAKE HOLD BY LATE MORNING. SOUTH WINDS WILL DEVELOP THIS AFTERNOON AS THE RIDGE PUSHES EAST WITH TEMPERATURES RISING TO AROUND FREEZING. LITTLE IN THE WAY OF DIURNAL TEMP FALLS EXPECTED TONIGHT WITH TIGHT PRESSURE GRADIENT DEVELOPING IN EASTERN KANSAS UNDER 30-50KT SOUTH 925MB WINDS. MODEST LOW LEVEL MOISTURE SHOULD RESULT IN STRATUS INTRUSION IN AT LEAST EASTERN AREAS. MAIN FOCUS FOR THE EARLY PERIODS IS STILL THE UPPER TROFS SPEED AND STRENGTH AS IT PASSES THROUGH THE PLAINS SUNDAY AND SUNDAY NIGHT. SIMILAR TO RUNS OF THURSDAY NIGHT...THE NAM IS ON THE QUICK SIDE...ECMWF ON THE SLOW SIDE...AND OTHERS IN BETWEEN. HAVE SIDED CLOSEST TO THE LARGER DOMAIN MODELS THINKING THEY SHOULD HAVE THE BEST HANDLE ON THIS OFF-SHORE SYSTEM...SPECIFICALLY CLOSEST TO THE ECMWF AND GEM. THIS DELAYS THE BEST PRECIPITATION CHANCES TO LATE SUNDAY AFTERNOON AND INTO SUNDAY EVENING. 850MB TEMPS RISE INTO THE 10-12C RANGE TONIGHT...AND DESPITE STRONG AND DEEP COLD AIR ADVECTION WITH THIS SYSTEM...CHANGEOVER TO AN ALL SNOW TYPE SHOULD BE DELAYED UNTIL SUNDAY EVENING. PRECIP WILL LIKELY COINCIDE WITH STRONG NORTHWEST WINDS BEHIND THE PACIFIC FRONT...BUT PRECIP RATES/AMOUNTS AND SPEEDS SHOULD BE LOW ENOUGH TO PRECLUDE ANY HEADLINES. DEEPER MIXING BEHIND THE SYSTEM MONDAY SHOULD PUSH HIGHS BACK INTO THE 40S. TREND FOR THE TUESDAY INTO WEDNESDAY PERIODS CONTINUES TO BE FOR BULK OF ENERGY WITH THE NEXT SHORTWAVE TO DIVE SOUTHEAST...WITH LITTLE FORCING FOR PRECIPITATION THIS FAR NORTH. THERE REMAINS SOME SIGNAL FOR LIGHT AND SPOTTY ACCUMS TO OCCUR...AND SOME MENTION WILL REMAIN FOR TUESDAY AFTERNOON IN THE WEST AND AREA-WIDE TUESDAY NIGHT. TEMPERATURE PROFILES SHOULD SUPPORT RAIN-SNOW AGAIN. ZONAL FLOW SHOULD MAINTAIN ITSELF NORTH OF THE UPPER LOW WITH SOMEWHAT ABOVE NORMAL TEMPS RESULTING. 65 && .AVIATION... SCT TO BKN MVFR CEILINGS WITH BASES OF 2200 FT TO 2800 FT WILL CONTINUE ACROSS THE TAF SITE THIS MORNING. WEAK ISENTROPIC LIFT ACROSS EASTERN KS THIS MORNING WILL SLOWLY DIMINISH AFTER 16Z ALLOWING SKIES TO BECOME CLEAR. NORTHEAST WINDS OF 5 TO 10 KTS THIS MORNING SWITCH TO THE SOUTHEAST AND SOUTH THROUGH THE AFTERNOON HOURS. GARGAN && .TOP WATCHES/WARNINGS/ADVISORIES... NONE. && $$
AREA FORECAST DISCUSSION
NWS GOODLAND KS
420 AM MST SAT JAN 21 2012 .DISCUSSION... 420 AM MST SAT JAN 21 2012 MAIN FORECAST PROBLEM WILL BE THE WINDS THROUGH SUNDAY BUT MANY OTHER CONCERNS ARE JUST BELOW THE WINDS. SATELLITE SHOWING AN ACTIVE/PROGRESSIVE WAVE TRAIN FROM THE PACIFIC INTO THE WESTERN ATLANTIC. BROAD UPPER TROUGH REMAINS IN PLACE OVER THE PACIFIC WITH A STRONG SHORTWAVE TROUGH APPROACHING THE WEST COAST. ALSO BIG LOW LEVEL TEMPERATURE GRADIENT SLIDING BACK AND FORTH ACROSS THE AREA. AT JET LEVEL...EXTREMELY STRONG JET OVER THE EASTERN PACIFIC BEHIND INCOMING TROUGH. BASED ON WHAT OBSERVATIONS ARE OUT THERE...THE MODELS ARE UNDERDOING THE STRENGTH OF THE NEAR 200 KNOT JET. BASED ON AVAILABLE DATA...THE GFS AND NAM LOOK TO HAVE THE BEST STRENGTH BUT THE NAM/CANADIAN HAVE BEST ORIENTATION. OVER THE COUNTRY...THE NAM AND CANADIAN HAVE THE BEST HANDLE ON THE JET THAT STARTED NEAR OUR AREA LAST NIGHT. THE OTHER MODELS TENDED TO BE TOO FAR EAST. SATELLITE AND UPPER AIR WOULD SUPPORT THE ECMWF/CANADIAN BEING THE BEST AT MID LEVELS. MODELS TENDED TO BE TOO MOIST AT MID LEVELS WITH THE CANADIAN AND UKMET DOING THE BEST. MODELS CONTINUING TO HAVE TROUBLE WITH THE LOW LEVEL THERMAL FIELD. OVERALL THE UKMET AND CANADIAN WAS DOING A LITTLE BETTER THAN THE GFS...ESPECIALLY WITH THE POSITION OF THE COLD POOL TO OUR NORTH AND EAST. TODAY/TONIGHT...NEWER GUIDANCE HAS COME IN A LITTLE STRONGER WITH THE WINDS. MODELS SHOW LITTLE TO NO MIXING TODAY WITH LOUSY LOW LEVEL LAPSE RATES. WHICH AM NOT ENTIRELY SURE ABOUT. INITIAL QUESTION TO HELP WITH THAT WILL BE HOW MUCH CLOUD COVER WILL MOVE IN TODAY. IMPRESSIVE CLOUD SHIELD OUT TO OUR WEST. THE BETTER MODELS IN REGARDS TO THIS MOISTURE WOULD SAY THAT THE CLOUDS REALLY DO NOT THICKEN UP UNTIL THIS AFTERNOON. HOWEVER...DESPITE THE LACK OF MIXING WHAT MAY BE THE MAIN DRIVING FORCE BEHIND THESE WINDS COULD THE TIGHTENING PRESSURE GRADIENT AND PRETTY HIGH 3 HOUR PRESSURE FALLS THROUGH THE AFTERNOON. GOING BY WHAT LIMITED MIXING BUFKIT SHOWS...WINDS LOOK TO REACH ADVISORY CRITERIA. IT WILL BE CLOSE BUT CHOSE TO ISSUE A WIND ADVISORY FOR ALL BUT THE FAR EASTERN TWO COUNTIES. ADVISORY MAY BE MARGINAL FOR THOSE EASTERN COUNTIES BUT WILL BE PLAYING THIS ON THE SAFE SIDE. MODELS HAVE HAD A HORRIBLE TIME WITH TEMPERATURE GRADIENT ACROSS THE AREA. THICKENING CLOUD COVER WILL MAKE THIS EVEN MORE PROBLEMATIC. LOW LEVEL THERMAL PROFILES CLUSTER AROUND A LITTLE WARMER TEMPERATURES THAN WHAT IS IN THERE. CANADIAN SURFACE TEMPERATURE MATCHES UP WELL WITH WHAT THE HRRR IS SHOWING. SO WARMED UP TEMPERATURES SOME IN LINE WITH THOSE MODELS. STRONG INCOMING SYSTEM BEGINS TO AFFECT THE AREA LATE TONIGHT. DEEPER MOISTURE AND LIFT ALONG WITH DECENT LAPSE RATES COME INTO THE WEST LATE. MORE MODEL QPF SHOWING QPF IN THIS AREA AND SEEMS REASONABLE CONSIDERING THE LIFT AND INSTABILITY. QUESTION THEN BECOMES PHASE. LOW LEVEL THERMAL GUIDANCE AND SOUNDING SHOW VERY MILD OVERNIGHT TEMPERATURES IN ADVANCE OF THE SYSTEM. THE ONLY PLACE THAT LOOKS TO BE NEAR FREEZING IS IN THE EAST WHERE PRECIPITATION IS NOT EXPECTED AT THIS TIME. RAISED MINS ACROSS THE REMAINDER OF THE AREA. CONSIDERING THE POSSIBILITY OF A LITTLE MORE INTENSE PRECIPITATION AND BEING A LITTLE WARM...DID A RAIN AND SNOW MIX IN THE FAR WEST WITH SPRINKLES TO THE EAST OF THERE. SUNDAY/SUNDAY NIGHT...LEFT FRONT QUADRANT OF THE JET STARTS OUT OVER THE EASTERN HALF OF THE AREA AT 12Z AND THEN IT QUICKLY MOVES EAST. STRONG UPPER TROUGH MOVES THROUGH DURING THE DAY. BASED ON SATELLITE...STRONG JET ASSOCIATED WITH THE SYSTEM...AND STRONG PV ANOMALY INDICATED...BELIEVE THE MODELS ARE UNDERDOING THE STRENGTH OF THE SYSTEM. COMBINATION OF STRONG LIFT/PV ANOMALY AND FAVORABLE THETA-E LAPSE RATES...WILL BRING A GOOD CHANCE OF A LIGHT MEASURABLE PRECIPITATION EVENT TO THE AREA. BASED ON THE PREVIOUS REASONING... GEFS PROBABILITIES...AND LOCAL POP PROGRAM...RAISED POPS OVER THE ENTIRE FORECAST AREA...ESPECIALLY IN THE EAST. DAY SHIFT WILL HAVE TO LOOK AT RAISING THESE POPS EVEN MORE. PHASE REMAINS A PROBLEM. MODELS DO NOT SHOW A LOT OF COLD AIR. IT IS POSSIBLE WITH THE MOST INTENSE PRECIPITATION SNOW COULD MIX WITH THE RAIN IN THE MORNING. AT THIS TIME KEPT THE MIXED PHASE IN THE MORNING WITH ALL RAIN IN THE AFTERNOON. HOWEVER...WHAT LOOKS TO BE THE MAIN STORY WILL ONCE AGAIN BE THE WINDS. STRONG SUBSIDENCE BEHIND THE WAVE/EXITING PRECIPITATION COMBINED WITH VERY GOOD LAPSE RATES AND 3 HOUR PRESSURE RISES SHOULD BRING A HIGH END WIND ADVISORY EVENT TO THE ENTIRE AREA. HOWEVER...STRONGEST 3 HOUR PRESSURE RISES ARE OUT AHEAD OF THE MAIN SUBSIDENCE. WHAT IS CONCERNING IS THAT IF PARAMETERS CAN COME TOGETHER A LITTLE BETTER...IT IS POSSIBLE THAT WARNING CRITERIA COULD BE MET. DAY SHIFT WILL HAVE TO LOOK AT THIS AGAIN...AND CHOOSE THE APPROPRIATE HIGHLIGHT. CHOSE TO GO SLIGHTLY BELOW THE GUIDANCE WHICH WAS IN PRETTY CLOSE AGREEMENT. PRECIPITATION SHOULD BE DONE BY THE NIGHT AND WILL PROBABLY COOL BELOW GUIDANCE. MONDAY/MONDAY NIGHT...QUESTION WILL BE HOW MUCH TO WARM TEMPERATURES. WILL HAVE A COLD START PLUS EXITING SURFACE HIGH AND DEVELOPING LEE TROUGH WILL CAUSE THE WINDS TO BE MORE FROM AN UPSLOPE DIRECTION. SO TRENDED SLIGHTLY COOLER THAN THAN GUIDANCE. NEXT FRONT STARTS MOVING THROUGH DURING THE NIGHT AND MADE NO CHANGES TO THE TONIGHT PERIOD. BULLER TUESDAY THROUGH FRIDAY...SHORTWAVE RIDGE BREAKS DOWN AS TROUGH OVER GREAT BASIN SHIFTS EAST ACROSS THE INTERMOUNTAIN WEST. GUIDANCE IN GENERAL AGREEMENT ON H5 CLOSED LOW DEVELOPING OVER NEW MEXICO TUESDAY MORNING...WITH SHORTWAVE TROUGH KICKING EAST ACROSS THE CWA BY 18Z TUESDAY. MOISTURE ISNT VERY IMPRESSIVE WITH THIS SYSTEM... WITH CLOSED LOW KEEPING GULF MOISTURE MUCH FURTHER SOUTH. HOWEVER THERE IS A NARROW WINDOW WHERE LARGE SCALE ASCENT AND LIMITED MOISTURE ADVECT IS PRESENT OVER PARTS OF THE CWA. FOR NOW HAVE KEPT SLIGHT CHANCE POPS ACROSS WESTERN LOCATIONS DURING THE DAY TUESDAY... AND IN THE FAR EASTERN DURING THE EVENING. SHORTWAVE RIDGE DEVELOPS ACROSS THE SW US WEDNESDAY AND THURSDAY AS TROUGH SHIFTS EAST...WITH NW FLOW JUST NORTH OF THIS FEATURE OVER THE CWA. LEE TROUGH DEVELOPS THURSDAY BENEATH THIS PATTERN WITH S/SW FLOW AT THE SURFACE SUPPORTING A BRIEF RETURN TO TEMPS IN THE 50S/NEAR 60 THURSDAY AFTERNOON. NW FLOW PERSISTS THROUGH FRIDAY...WITH SHORTWAVE TROUGH PUSHING EAST TOWARDS THE PLAINS FRIDAY NIGHT. GUIDANCE IS ALL OVER THE PLACE ON THE EXACT TRACK OF THIS FEATURE...SO NOT ENOUGH CONFIDENCE TO ADD PRECIP AT THIS POINT. DR THANKS TO ALL THAT COLLABORATED. && .AVIATION... 420 AM MST SAT JAN 21 2012 FOR THE 12Z TAFS...VFR CONDITIONS ARE EXPECTED THROUGH THE PERIOD AT BOTH KGLD AND KMCK TERMINALS. SOUTHERLY WINDS WILL INCREASE THROUGH THE MORNING AT BOTH TERMINALS AS LEE TROUGH STRENGTHENS THROUGH THE DAY. AFTERNOON GUSTS UP TO 40KT ARE POSSIBLE AT KGLD...WITH GUSTS AROUND 30KT AT KMCK. WHILE WINDS SHOULD DECREASE AT BOTH TERMINALS AFTER 00Z...I STILL EXPECT GUSTY CONDITIONS TO CONTINUE THROUGH MOST OF THE EVENING AT KGLD. WINDS WILL SHIFT TO THE WEST AROUND 09-10Z AT BOTH TERMINALS AS SURFACE TROUGH SHIFTS EAST. DR && .GLD WATCHES/WARNINGS/ADVISORIES... KS...WIND ADVISORY FROM 10 AM MST /11 AM CST/ THIS MORNING TO 6 PM MST /7 PM CST/ THIS EVENING FOR KSZ001>003-013>015-027>029- 041-042. FIRE WEATHER WATCH FROM SUNDAY MORNING THROUGH SUNDAY AFTERNOON FOR KSZ013-027-041. NE...WIND ADVISORY FROM 10 AM MST /11 AM CST/ THIS MORNING TO 6 PM MST /7 PM CST/ THIS EVENING FOR NEZ079>081. CO...WIND ADVISORY FROM 10 AM THIS MORNING TO 6 PM MST THIS EVENING FOR COZ090>092. FIRE WEATHER WATCH FROM SUNDAY MORNING THROUGH SUNDAY AFTERNOON FOR COZ252>254. && $$
AREA FORECAST DISCUSSION
NWS CARIBOU ME
931 AM EST SAT JAN 21 2012 .SYNOPSIS... LOW PRESSURE WILL TRACK SOUTH OF THE GULF OF MAINE TODAY. HIGH PRESSURE WILL THEN BUILD ACROSS THE REGION SUNDAY AND MOVE EAST OF THE AREA EARLY MONDAY. && .NEAR TERM /THROUGH TONIGHT/... UPDATE: HRRR MODEL STILL INDICATING NORTHERN EDGE OF SNOW WILL MOVE ACROSS DOWNEAST THIS AFTERNOON WITH A PERIOD OF LIGHT SNOW SO WILL KEEP POPS GOING FOR DOWNEAST TODAY. ANY SNOW ACCUMULATION WILL BE LESS THAN AN INCH. PREV DISC: LOW PRESSURE WILL TRACK SOUTH OF NEW ENGLAND TODAY. THE PRECIPITATION FROM THIS SYSTEM IS ONLY EXPECTED TO EFFECT THE SOUTH. HAVE USED A BLEND OF THE NAM12...GFS40 AND SREF FOR POPS. WILL ADJUST THIS BLEND MANUALLY TO KEEP LOWER POPS FURTHER SOUTH. HAVE USE A BLEND OF NAM12 AND GFS40 FOR WIND. HIGH PRESSURE WILL BUILD IN FROM THE NORTHWEST SUNDAY. FOR TEMPERATURE AND DEW POINT WILL USE GMOS AND ADJUST LOW TEMPERATURE LOWER SUNDAY MORNING TO ACCOUNT FOR RADIATIONAL COOLING. FOR QPF HAVE BLENDED THE NAM12 AND GFS40. && .SHORT TERM /SUNDAY THROUGH MONDAY/... A THAW LOOKS TO BE IN ORDER COME MONDAY W/LOW PRES MOVING THROUGH THE WESTERN QUEBEC PROVINCE. A NICE DAY IS IN STORE FOR SUNDAY W/A A GOOD DEAL OF SUNSHINE AS HIGH PRES SETTLES RIGHT ACROSS THE STATE. TEMPERATURES WILL BE WARMER THAN THEY WERE SATURDAY HITTING THE MID/UPPER TEENS NORTH AND LOW TO MID 20S ACROSS THE CENTRAL AND DOWNEAST REGION. HIGH PRES WILL SLIDE E SUNDAY NIGHT W/A RETURN FLOW FROM THE ESE BEGINNING TO SETUP. HIGH CLOUDINESS IS SHOWN BY THE GFS AND THE NAM TO MOVE ACROSS THE REGION SUNDAY NIGHT AS WAA BEGINS TO SET UP. TEMPERATURES WILL DROP BACK IN THE EVENING AND THEN ARE SHOWN TO LEVEL OFF BEFORE RISING EARLY MONDAY MORNING. ATTM, STAYED CLOSE TO THE DAYCREW/S ASSESSMENT OF SINGLE NUMBERS ACROSS THE NORTHERN AND WESTERN SECTIONS AND LOW TO MID TEENS FOR THE CENTRAL AND DOWNEAST REGIONS. THIS WILL NEED TO BE LOOKED AT AGAIN AS ANY PROLONGED CLEARING WILL ALLOW FOR TEMPERATURES TO FALL OFF MORE BEFORE LEVELING OFF. INCREASING CLOUDS FOR MONDAY W/A SSE FLOW SETTING UP AND MOISTURE GETTING PULLED NORTHWARD. STRATUS LOOKS LIKE IT COULD ADVECT IN W/THIS SETUP. ECMWF HOLDS ON TO LLVL COLD AIR LONGER W/DAMMING ACROSS THE ENE SECTIONS OF THE CWA. THE NAM AND THE CANADIAN HEMISPHERIC INDICATE THIS TO BE THE CASE AS WELL. THE GFS BREAKS DOWN THE DAMMING QUICKER. THEREFORE, DECIDED TO CUT BACK MAXES ON MONDAY W/THE SETUP PLUS WARMING TENDS TO HOLD BACK A BIT W/A SE FLOW GETTING STARTED(HISTORICALLY SPEAKING). PRECIP CHANCES WERE HELD BACK SOME W/RIDGE HOLDING IN LONGER. LOOKS LIKE SOME MIX OF RAIN/SNOW AND SLEET INITIALLY LATE MONDAY ACROSS THE NORTH AND WEST W/RAIN OVER THE DOWNEAST AND POINTS SOUTH. TEMPERATURES WILL CONTINUE TO SLOWLY RISE MONDAY NIGHT AND THIS WILL BE ADDRESSED BELOW. && .LONG TERM /MONDAY NIGHT THROUGH FRIDAY/... THE MAIN CHALLENGE THIS TERM WILL BE TEMPERATURES AND PRECIP TYPE EARLY IN THE TERM. OCCLUSION IS SHOWN BY THE LONG RANGE GUIDANCE INCLUDING THE CANADIAN HEMISPHERIC TO LIFT NORTHWARD MONDAY NIGHT AND SWING ACROSS THE REGION ON TUESDAY. THE NAM/ECMWF SHOW A WEAK LOW DEVELOPING ON THE OCCLUSION AND MOVING ACROSS EASTERN MAINE. THIS COULD ENHANCE PRECIP AND POSSIBLY CUT OFF SIGNIFICANT WARMING WHILE THE CANADIAN HEMISPHERIC HINTS AT SOMETHING SIMILAR BUT IS FURTHER WEST WHICH WOULD ALLOW FOR MORE WARMER AIR TO BE PULLED NORTHWARD. THE GFS AND ITS ENSEMBLE MEAN KEEP THE OCCLUSION SWEEPING THROUGH THE REGION ON TUESDAY. DAYCREWS POPS LOOKED GOOD AND MODIFICATIONS MADE ONLY FOR PLACEMENT AND BROUGHT THE VALUES UP SOME BUT STILL IN THE LIKELY TO CATEGORICAL RANGE. SOME SLEET AND RAIN POSSIBLE ACROSS THE FAR NORTH EARLY MONDAY EVENING BUT THE COLUMN SHOULD BE WARM ENOUGH TO ALLOW FOR RAIN. AN INTERESTING NOTE IS THAT THE HEMISPHERIC GUIDANCE SHOWS 40S AND 50S TUESDAY AFTERNOON. THIS IS THE ONLY GUIDANCE THAT IS SHOWING THIS TO BE THE CASE. A BLEND OF THE GMOS AND GFS WAS USED FOR THE TEMPERATURES WHICH INDICATE A WARMER SCENARIO FOR TUESDAY W/TEMPERATURES HITTING THE MID AND UPPER 30S NORTH AND WEST AND 40S CENTRAL AND DOWNEAST. THE FRONT CLEARS THE REGION BY TUESDAY EVENING W/THE GRADUAL COOL DOWN AND WHATEVER PRECIP IS LEFTOVER TRANSITIONING TO SNOW SHOWERS MAINLY NORTH & WEST. HELD BACK THE COOLING FOR ABOUT 6 HRS AS PAST EVENTS SIMILAR TO THIS SHOW MODELS TO BE TOO FAST W/BRINGING THE COLDER AIR BACK IN BEHIND THE OCCLUSION. UPPER TROF WILL NEED TO MOVE THROUGH FOR THAT TO HAPPEN. GMOS/GFS TEMPERATURES WERE BLENDED FOR TUESDAY NIGHT AS WELL. THE ASSOCIATED COLD FRONT WILL MAKE ITS WAY ACROSS THE CWA ON WEDNESDAY W/MUCH COLDER TEMPERATURES FOR MID TO LATE WEEK AS ADVERTISED BY THE GFS AND ECMWF. GMOS WAS USED FROM WEDNESDAY ONWARD BUT PULLED BACK POPS TO BELOW 20% THURSDAY INTO FRIDAY W/HIGH PRES BUILDING ACROSS THE REGION. ECMWF BRINGS A LOW ACROSS THE GULF OF MAINE LATE NEXT FRIDAY W/AN INVERTED TROF HANGING BACK ACROSS THE REGION SIMILAR TO THIS PASS EVENT YESTERDAY(FRIDAY1/20). THIS WOULD MEAN POTENTIAL SNOW FOR THE CWA. THE ECMWF IS THE ONLY GUIDANCE SHOWING THIS AS THE GFS AND ITS ENSEMBLES SHOW THE LOW TO DEVELOP WELL SOUTH OF THE CWA. STILL PLENTY OF TIME TO LOOK AT THIS AS THIS IS DAY 7!. && .AVIATION /13Z SATURDAY THROUGH WEDNESDAY/... NEAR TERM: MAINLY VFR CONDITIONS TODAY AND TONIGHT EXCEPT FOR A PERIOD OF MVFR IN LIGHT SNOW ACROSS DOWNEAST TERMINALS LATE MORNING INTO EARLY AFTERNOON. SHORT TERM: VFR FOR SUNDAY AND THEN POTENTIAL FOR MVFR/IFR ON MONDAY W/SSE FLOW SETTING UP W/MOISTURE GETTING PULLED IN FROM THE ATLC OCEAN. MONDAY NIGHT INTO TUESDAY LOOK TO BE IFR AND EVEN LIFR AT LEAST EARLY IN THE DAY. LLWS ALSO A POSSIBILITY EARLY TUESDAY. && .MARINE... NEAR TERM: AS LOW PRESSURE MOVES SOUTHEAST OF THE WATERS, MAY HAVE A PERIOD OF SCA WINDS ON THE BACK SIDE OF THE LOW PRESSURE TONIGHT MAINLY OVER OUR OUTER WATERS. SHORT TERM: SCA CONDITIONS BY MONDAY W/POTENTIAL FOR A BRIEF PERIOD OF GALES EARLY TUESDAY W/THE OCCLUSION. USED THE NAM12 AND GFS THROUGH EARLY TUESDAY WHICH SUPPORTS GUSTS HITTING 35+ KTS FROM 12-18Z TUESDAY AS LLVL JET OF 50 KTS IS SHOWN TO PASS OVER THE WATERS. HELD ONTO THE DAYCREWS WAVE HEIGHTS OF INCREASING SEAS TO 10-13FT BY TUESDAY W/SSE FLOW. FOLLOWED WNAWAVE FROM TUESDAY NIGHT INTO WEDNESDAY SHOWING A DECREASING TREND IN SEAS. && .CAR WATCHES/WARNINGS/ADVISORIES... ME...NONE. MARINE...SMALL CRAFT ADVISORY FROM 9 PM THIS EVENING TO 4 AM EST SUNDAY FOR ANZ050-051. && $$ NEAR TERM...FOSTER/MIGNONE SHORT TERM...HEWITT LONG TERM...HEWITT AVIATION...FOSTER/MIGNONE MARINE...FOSTER/MIGNONE/HEWITT
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
951 AM EST SAT JAN 21 2012 .SYNOPSIS... WHATS LEFT OF THE WINTRY MIX WILL END BY NOONTIME AS LOW PRESSURE EXITS EAST PAST THE WEST VIRGINIA MOUNTAINS. HIGH PRESSURE, COMING EAST FROM WISCONSIN, WILL PROVIDE A DRY BREAK THIS AFTERNOON INTO SUNDAY EVENING. A COLD FRONT, COMING EAST FROM THE ROCKIES, WILL THEN BRING RAIN SHOWERS LATE SUNDAY NIGHT AND MONDAY, FOLLOWED SCATTERED SNOW SHOWERS LATE MONDAY NIGHT INTO TUESDAY. && .NEAR TERM /THROUGH TONIGHT/... PER RECENT SURFACE AND RADAR DATA HAVE FORECASTED A SLIGHTLY FASTER END OF THE WINTRY MIX. HENCE HAVE DROPPED ADDITIONAL COUNTIES FROM WINTER WEATHER HEADLINES, ONLY LEAVING THE MOUNTAINS WITH HEADLINES UNTIL 12 PM. PER RECENT SATELLITE DATA AND HRRR MODEL OUTPUT, HAVE FORECASTED THINNING CLOUDS IN WAKE OF EXITING LOW PRESSURE SYSTEM. HAVE MAINTAINED A SLOW DECREASE IN CLOUD COVERAGE AS NAM MODEL PROFILES SUGGEST STRATOCUMULUS CAN REMAIN IN A THIN SATURATED LAYER BENEATH A STRENGTHENING SUBSIDENCE INVERSION NEAR 4 KFT AGL. HAVE CUT TEMPERATURE INCREASE THIS AFTERNOON, INFLUENCED BY RECENT HRRR AND GFS LAMP MODEL OUTPUT, TO PRETTY MUCH MAINTAIN STEADY TEMPERATURES THIS AFTERNOON. PART OF THIS IS DUE TO COLD ADVECTION AND LINGERING CLOUDS, AND PART DUE TO REFRIGERATING, REFLECTIVE EFFECTS OF FRESH SNOW AND ICE COVER. FOR TONIGHT, EXPECT CLOUDS TO DECREASE. HAVE LOWERED LOW TEMPERATURES DUE TO EXPECTED INCREASE IN RADIATIVE COOLING ABOVE FRESH SNOW AND ICE COVER. && .SHORT TERM /SUNDAY THROUGH MONDAY/... RECENT SREF MODEL OUTPUT CONTINUES TO SHOW HIGH PRESSURE, COMING EAST FROM THE PLAINS, WILL PROVIDE A DRY BREAK INTO SUNDAY EVENING. THEN EXPECT LOW PRESSURE, MOVING EAST ACROSS SOUTHERN CANADA, TO DRIVE A COLD FRONT THROUGH THE UPPER OHIO VALLEY MONDAY AFTERNOON. THE FRONTAL BAND OF SHOWERS SHOULD SPREAD EASTWARD THROUGH THE AREA, STARTING LATE SUNDAY NIGHT. FORECASTED TEMPERATURES, USING BLEND OF NAM AND GFS MOS, TO WARM ABOVE FREEZING SUNDAY AND STAY ABOVE FREEZING INTO LATE MONDAY. HIGHS MONDAY CAN BE 10 DEGREES WARMER THAN NORMAL. PREFRONTAL SOUTHEAST WINDS MAY GUST OVER 30 MPH DOWNWIND FROM THE MOUNTAINS SUNDAY NIGHT. && .LONG TERM /MONDAY NIGHT THROUGH FRIDAY/... A LOW PRESSURE SYSTEM WILL EXIT THE GREAT LAKES REGION AND MOVE INTO SOUTHERN QUEBEC BY TUESDAY. SHOWERS WILL TAPER OFF TUESDAY AND COULD CHANGE OVER TO SCATTERED SNOW SHOWERS BEFORE ENDING IN THE AFTERNOON. A RIDGE OF HIGH PRESSURE SHOULD PROVIDE DRY WEATHER ON WEDNESDAY. MEDIUM RANGE MODELS SHOW A NORTHERN BRANCH SHORT WAVE TROUGH MOVING EAST INTO THE GREAT LAKES REGION BY THURSDAY. MEANWHILE...A SOUTHERN BRANCH CLOSED LOW MEANDERS GENERALLY EASTWARD ACROSS TX AND INTO THE LOWER MS VALLEY LATE IN THE WEEK. MODELS DIFFER ON EVOLUTION AND TRACK OF ASSOCIATED SURFACE LOWS THURSDAY INTO FRIDAY. OUR PLAN IS TO STICK WITH HPC GUIDANCE WITH CHANCE POPS BEGINNING WEDNESDAY NIGHT AND CONTINUING INTO FRIDAY. TEMPERATURES ARE FORECAST TO REMAIN GENERALLY BETWEEN 5 AND 10 DEGREES ABOVE NORMAL DURING THE EXTENDED PERIOD. && .AVIATION /15Z SATURDAY THROUGH WEDNESDAY/... VISIBILITIES HAVE IMPROVED TO MVFR IN LIGHT FOG IN WAKE OF ENDING PRECIPITATION, AND WILL BECOME UNRESTRICTED THIS AFTERNOON. POST SYSTEM COOLING, COMBINED WITH SUBSIDENCE ALOFT, WILL MAINTAIN A STRATOCUMULUS DECK INTO EARLY EVENING. CEILINGS WILL SLOWLY LIFT FROM IFR LEVELS TO MVFR LEVELS THIS AFTERNOON. SURFACE WINDS WILL BE FROM THE NORTH NEAR 10 KTS THIS AFTERNOON, THEN BECOME NORTHEAST NEAR 5 KTS TONIGHT. EXPECT VFR LATE TONIGHT, BUT NAM MODEL PROFILES SHOW STRONG SURFACE INVERSION DUE TO RADIATIVE EFFECTS OVER FRESH SNOW AND ICE COVER. SO HAVE SOME CONCERN OF EARLY MORNING FOG WITH RESTRICTIONS DEVELOPING, BUT NOT CONFIDENT TO INCLUDE IN TAF FORECAST. OUTLOOK...SUNDAY THROUGH WEDNESDAY... VFR INTO EARLY SUNDAY NIGHT. COLD FRONTAL BANDS OF RAIN SHOWERS WITH LIKELY RESTRICTIONS LATE SUNDAY NIGHT INTO MONDAY NIGHT. POST FRONTAL SCATTERED SNOW SHOWERS MAY CAUSE LINGERING RESTRICTIONS INTO TUESDAY. VFR WEDNESDAY. && .PBZ WATCHES/WARNINGS/ADVISORIES... MD...WINTER STORM WARNING UNTIL NOON EST TODAY FOR MDZ001. OH...NONE. PA...WINTER STORM WARNING UNTIL NOON EST TODAY FOR PAZ074-076. WV...WINTER WEATHER ADVISORY UNTIL NOON EST TODAY FOR WVZ023-041. && $$
AREA FORECAST DISCUSSION
NWS WAKEFIELD VA
713 AM EST SAT JAN 21 2012 .SYNOPSIS... LOW PRESSURE CENTERED OVER THE TENNESSEE VALLEY WILL TRACK EAST TODAY AND MOVE VERY SLOW THROUGH THE MID ATLANTIC REGION. THE ASSOCIATED COLD FRONT WILL PUSH SOUTHEAST LATE THIS AFTERNOON AND EVENING AS STRONG HIGH PRESSURE BUILDS SOUTH FROM NEW ENGLAND OVERNIGHT INTO SUNDAY. A STRONGER COLD FRONT WILL AFFECT THE AREA ON MONDAY...FOLLOWED BY HIGH PRESSURE BUILDING OVER THE SOUTHEAST STATES TUESDAY INTO WEDNESDAY. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... UPDATED FCST TO ADD WINTER WX ADSY FOR SOME OF THE NW COUNTIES...AS AREA OF MODERATE PRECIPITATION IS OVERSPREADING THIS AREA...AND SHOULD COINCIDE WITH TEMPS 32 F OR COLDER FOR ABOUT 3 HRS. USING LATEST RUC SFC- WET BULB TEMPERATURES SEEMS TO HAVE THE BEST HANDLE ON THE CURRENT OBS...LOW LEVEL COLD AIR IS VERY SHALLOW...SUCH THAT EVEN 1000-850 MB THICKNESSES ARE VERIFYING TOO WARM. OTHERWISE...AREAS FARTHER TO THE SE OF THE ADVSY SHOULD ENCOUNTER JUST RAIN FOR THE REST OF THE DAY...6 AM OBS SHOW DEW PT AT 34 F AT RIC...SO THAT EVAPORATIVE COLUMN COOLING WILL NOT LOWER THE TEMPS AS THEY DID LAST EVENING...SOME SPOTTY -FZRA MAY BE POSSIBLE OVER EXTREME NW PORTIONS OF THE COUNTIES BORDERING THE ADSY BUT ANY ACCUMULATION IS NOT LIKELY...AS SFC TEMPS SHOULD BE ABOVE FREEZING SHORTLY. LATER TODAY...RA/SHRA SHOULD COVER ALL AREAS BY LATE MORNING OR EARLY AFTN. SOUTH OF THE BOUNDARY...ADDED ISO TSTMS FOR THE AFTN IN SE VA/NE NC WHERE TEMPS RISE INTO THE UPR 50S TO MID 60S W/ DEW PTS IN THE 50S. CURRENT AREA OF CONVECTION OVER KY/TN WILL LIKELY BREAK APART WHEN IT INTERACTS W/ THE MTNS BUT MAY RE- GENERATE THIS AFTN. ONLY MINIMAL INSTABILITY BUT THERE IS DECENT SHEAR SO AN ISO STRONGER STORM IS POSSIBLE/MAIN THREAT BEING STRONG WINDS. && .SHORT TERM /6 PM THIS EVENING THROUGH MONDAY/... TONIGHT...MODELS AGREE THAT N/NE FLOW WILL OVERSPREAD THE ENTIRE CWA BY 00Z...AS SFC LOW PUSHES OFF THE NC COAST. STILL LOTS OF LOW LEVEL MOISTURE...BUT MID LEVEL DRYING FROM THE NORTH SHOULD BRING AN END TO MOST OF THE PRECIP BETWEEN 00-03Z EXCEPT IN NE NC WHERE IT LINGERS A FEW HRS LONGER. WV SATELLITE SUGGEST STRONG AREA OF MID-UPPER CONFLUENCE OVER HUDSON BAY WILL SLIDE SE...ALLOWING WITH A 1035 MB SFC HIGH TO BUILDING INTO ERN NY STATE/NEW ENGLAND. COLD AIR FILTERS SOUTH ONCE AGAIN...BUT PRETTY GOOD CONSENSUS THAT THIS WILL HOLD OFF UNTIL AFTER BULK OF PRECIP ENDS...I.E. PRECIP ENDS BEFORE PTYPE CONCERNS BECOME A MAJOR ISSUE. FOR NOW WILL MENTION POTENTIAL FOR FREEZING DRIZZLE ACRS NRN ZONES BEGINNING AFTER ABOUT 03Z. LOWS IN THE UPR 20S NORTH...UPR 30S S. SUN/SUN NIGHT...LOOKS TO BE A COLD DAY ON SUNDAY WITH NE FLOW. ONLY CONCERN WOULD BE FOR FREEZING DRIZZLE IN THE MORNING OVER CENTRAL VA...INCLUDING METRO RICHMOND AND AREAS ON NW AS LOW LEVELS REMAIN BELOW CRITICAL THRESHOLDS FOR FROZEN PRECIP. VERY DRY ALOFT HOWEVER...SO THIS WOULD BE NOTHING MORE THAN FREEZING DRIZZLE...WILL MAKE AN HWO MENTION FOR NOW. SHOULD BE WARM ENOUGH FOR JUST -RADZ BY AFTN (EXCEPT COULD BE CLOSE IN THE COLDER FAR NW ZONES. DOUBT WE`LL SEE ANY BREAKS IN THE CLOUD COVER AS LOW LEVEL INVERSION WILL BE DIFFICULT TO MIX OUT...PERHAPS A FEW PEEKS OF SUN IN THE MORNING OVER THE FAR NORTH CLOSEST TO THE SFC HIGH. BREEZY CONDITIONS ALONG THE COAST. FAVOR THE COLDER MET NUMBERS FOR HIGHS...BASED ON LIMITED MIXING AND A LOW OVC...HIGHS RANGING FROM THE UPPER 40S FAR SE VA/NE NC...MID- UPPER 30S NW ZONES. TEMPS RISE OVERNIGHT SUNDAY NIGHT...AS SFC HIGH OVER NEW ENGLAND RETREATS OFF TO THE NE...FOLLOWED BY SIGNIFICANT WARM-UP ON MON AHEAD OF THE NEXT SYSTEM. FAVOR THE WARMER MAV VALUES ON MON W/ SSW FLOW BY LATE MORNING AFTN...HIGHS GENLY IN THE UPR 50S NW (WHERE PRECIP COMES IN EARLIER) TO THE MID- UPR 60S SE. CHC TO LIKELY POPS FOR SHOWERS ALL AREAS. && .LONG TERM /MONDAY NIGHT THROUGH FRIDAY/... A SERIES OF WAVES WILL PASS NORTH OF THE FA DURING THE LONG TERM PERIOD DRAGGING COLD FRONTS AND PERIODS PRECIP THROUGH THE AREA. RAIN WILL BEGIN TO IMPACT THE AREA MONDAY AS AN UPPER LEVEL WAVE PASSES OVER NORTHERN MICHIGAN. THE ASSOCIATED COLD FRONT CROSSES THE AREA BRINGING A PERIOD OF RAIN AND A WIND SHIFT FROM THE S TO N. THE MODELS VARY A BIT WITH THE STRENGTH OF THE SYSTEM...AND HAVE LEANED TOWARD THE WEAKER ECMWF. BUT...IF THE GFS VERIFIES THERE COULD BE A COUPLE TSTMS THAT DEVELOP IN NE NC AND SE VA. BENIGN WX PREVAILS AS HIGH PRESSURE BUILDS OVER THE AREA TUESDAY NIGHT AND SLIDES OFF THE COAST BY THURSDAY EVENING. THE NEXT SYSTEM LOOKS TO IMPACT THE AREA FRIDAY MORNING AS A WARM FRONT BRINGS RAIN INTO THE AREA...FOLLOWED BY A COLD FRONT THAT WILL BRING ANOTHER ROUND OF RAIN LATE FRI/EARLY SAT. AGAIN THERE IS A BIT OF DISAGREEMENT WITH THE MODEL TIMING OF THIS EVENT. THE ECMWF PROGRESSES THE UPPER LEVEL SYSTEM EAST MUCH MORE QUICKLY THAN THE GFS. BEING THIS FAR OUT IN THE FORECAST...JUST TRIED TO BLEND THE TIMING OF THE SCENARIOS TOGETHER. EXPECT A BIT OF A ROLLER COASTER AS FAR AS TEMPS GO DURING THE PERIOD. WITH THE APPROACH THE SYSTEM MONDAY...EXPECT HIGHS IN THE MID 60S NORTH TO UPPER 60S SOUTH. AS THE FRONT CLEARS THE AREA MILDER TEMPS WILL PREVAIL WITH HIGHS IN THE MID 50S TO 60 FOR TUES AND WED. A WARMER DAY FOLLOWS ON THUR AS WINDS TURN SOUTH AHEAD OF THE NEXT FRONT. LOWS WILL BE IN THE LOW 40S TUES...FALLING TO THE LOW AND MID 30S FOR WED AND THUR...WARMING INTO THE MID 40S FOR FRI AND SAT. && .AVIATION /12Z SATURDAY THROUGH WEDNESDAY/... ONGOING LIGHT TO MOD PCPN THIS MORNING IN ASSOCIATION WITH WEAK ISENTROPIC LIFT. MVFR/TEMPO IFR CONDS ACROSS ALL BUT FAR SE TERMINALS AS OF 7A. CONDITIONS DETERIORATING AS EXPECTED OVER FAR NORTHERN ZONES...WITH IFR CONDS EXPECTED AT NORTHERN TERMINALS THROUGHOUT THE DAY. PCPN REMAINS IN FORM OF VERY LIGHT FZRA N OF KRIC/KSBY...AND WL NEED TO KEEP AN EYE ON TRENDS AS THE MORNING PROGRESSES. HV ACCOUNTED FOR PERIODS OF RA/DZ ACROSS SITES THIS MORNING...WITH DETERIORATING CONDS AS NEXT SLUG OF OVERRUNNING MOISTURE ARRIVES FROM THE WEST. S/SE WINDS VEER TOWARDS THE W/SW LATER THIS MORNING AS A WARM FRONT LIFTS ACROSS THE AREA, BEFORE TURNING BACK TO THE NORTH LATE THIS AFTN AS LOW PRESSURE TRACKS TO OUR WEST/NORTHWEST, PUSHING A COLD FRONT THROUGH THE AREA TONIGHT. OUTLOOK: ALTHOUGH PCPN IS EXPECTED TO END TONIGHT...WIDESPREAD IFR IS FCST TO CONTINUE SUNDAY AND INTO MONDAY. A CHANCE FOR RAIN RETURNS WITH THE NEXT COLD FRONT PASSAGE ON MONDAY WITH IMPROVING CONDITIONS BEHIND THE FRONTAL PASSAGE FOR TUESDAY THROUGH MIDWEEK. && .MARINE... HV UPDATED SCA IN BAY TO BEGIN WITH 7AM ISSUANCE. WINDS TO MARGINAL/LOW END SCA FOR A FEW HOURS THIS MORNING BEFORE DIMINISHING BRIEFLY AS WINDS BECOME W/SW. WINDS RAMP BACK UPWARDS BEHIND FRONTAL PASSAGE THIS AFTN. PREV DISCUSSION... LATEST WX ANALYSIS/OBSERVATIONS SHOWS WARM FRONT DRAPED JUST SOUTH OF THE WATERS THIS MORNING...RESULTING IN E-SE WINDS AS OF 12Z. WINDS WILL CONTINUE TO VEER TOWARDS THE S-SW THIS MORNING AS WARM FRONT PUSHES NORTH (WHILE INCREASING IN SPEED (TO AVG 15-20 KT)) THROUGH MIDDAY. WARM FRONT WILL PUSH NORTH OF THE WATERS THIS MORNING AND MEANDER JUST NORTH OF THE WATERS EARLY THIS AFTN...BEFORE BEING SHUNTED BACK S ACROSS THE WATERS LATE THIS AFTN INTO TONIGHT AS SFC LOW PRES MOVING ACROSS NC PUSHES OFFSHORE. RESULTANT WIND DIRECTION WILL VEER AROUND TO THE N-NE BEHIND THE FRONTAL PASSAGE. PRESSURE GRADIENT WILL TIGHTEN SIGNIFICANTLY AS SFC HIGH PRESSURE CURRENTLY OVER THE UPPER MIDWEST SLIDES ACROSS NORTHEAST US. THIS WILL RESULT IN WINDS RAMPING UPWARDS INTO SCA CRIT RANGE (20 TO 25 KT)...WITH HIGHEST WINDS EXPECTED AFTER 00Z/7PM TONIGHT THROUGH SUN MRNG. WINDS BEGIN TO DIMINISH AS GRADIENT SLACKENS SUN AFTN...THOUGH RMN FM THE NE. ONLY MINOR CHANGE TO SCA WAS TO RUN THROUGH SUN AFTN OVER THE BAY, AND THROUGH LATE SUNDAY NIGHT OVER THE COASTAL WATERS. WINDS BECOME LIGHT SUNDAY NIGHT INTO EARLY MONDAY AS HIGH PRESSURE CONTINUES TO BUILD OVERHEAD, BUT RAMP UPWARDS GRADUALLY MONDAY AFTN AHEAD OF THE NEXT FRONTAL SYSTEM WHICH APPROACHES FROM THE W MONDAY. WINDS WL INITIALLY BE HIGHER OVER LAND MONDAY AFTN, BUT EVENTUALLY EXPECT ANOTHER ROUND OF SCA CONDITIONS BY MONDAY NIGHT. CONDITIONS IMPROVE BACK BELOW SCA CRITERIA ON TUE AS HIGH RPESSURE REBUILDS INTO THE REGION FROM THE WEST. && .AKQ WATCHES/WARNINGS/ADVISORIES... MD...NONE. NC...NONE. VA...WINTER WEATHER ADVISORY UNTIL 10 AM EST THIS MORNING FOR VAZ048-049-062>064. MARINE...SMALL CRAFT ADVISORY UNTIL 3 PM EST SUNDAY FOR ANZ630>632-634. SMALL CRAFT ADVISORY FROM NOON TODAY TO 3 PM EST SUNDAY FOR ANZ633. SMALL CRAFT ADVISORY FROM 3 PM THIS AFTERNOON TO MIDNIGHT EST SUNDAY NIGHT FOR ANZ650-652-654. SMALL CRAFT ADVISORY FROM 6 PM THIS EVENING TO MIDNIGHT EST SUNDAY NIGHT FOR ANZ656-658. && $$ SYNOPSIS...LKB NEAR TERM...LKB SHORT TERM...LKB LONG TERM...DAP AVIATION...MAM MARINE...MAM
AREA FORECAST DISCUSSION
NWS WAKEFIELD VA
602 AM EST SAT JAN 21 2012 .SYNOPSIS... LOW PRESSURE CENTERED OVER THE TENNESSEE VALLEY WILL TRACK EAST TODAY AND MOVE VERY SLOW THROUGH THE MID ATLANTIC REGION. THE ASSOCIATED COLD FRONT WILL PUSH SOUTHEAST LATE THIS AFTERNOON AND EVENING AS STRONG HIGH PRESSURE BUILDS SOUTH FROM NEW ENGLAND OVERNIGHT INTO SUNDAY. A STRONGER COLD FRONT WILL AFFECT THE AREA ON MONDAY...FOLLOWED BY HIGH PRESSURE BUILDING OVER THE SOUTHEAST STATES TUESDAY INTO WEDNESDAY. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... UPDATED FCST TO ADD WINTER WX ADSY FOR SOME OF THE NW COUNTIES...AS AREA OF MODERATE PRECIPITATION IS OVERSPREADING THIS AREA...AND SHOULD COINCIDE WITH TEMPS 32 F OR COLDER FOR ABOUT 3 HRS. USING LATEST RUC SFC- WET BULB TEMPERATURES SEEMS TO HAVE THE BEST HANDLE ON THE CURRENT OBS...LOW LEVEL COLD AIR IS VERY SHALLOW...SUCH THAT EVEN 1000-850 MB THICKNESSES ARE VERIFYING TOO WARM. OTHERWISE...AREAS FARTHER TO THE SE OF THE ADVSY SHOULD ENCOUNTER JUST RAIN FOR THE REST OF THE DAY...6 AM OBS SHOW DEW PT AT 34 F AT RIC...SO THAT EVAPORATIVE COLUMN COOLING WILL NOT LOWER THE TEMPS AS THEY DID LAST EVENING...SOME SPOTTY -FZRA MAY BE POSSIBLE OVER EXTREME NW PORTIONS OF THE COUNTIES BORDERING THE ADSY BUT ANY ACCUMULATION IS NOT LIKELY...AS SFC TEMPS SHOULD BE ABOVE FREEZING SHORTLY. LATER TODAY...RA/SHRA SHOULD COVER ALL AREAS BY LATE MORNING OR EARLY AFTN. SOUTH OF THE BOUNDARY...ADDED ISO TSTMS FOR THE AFTN IN SE VA/NE NC WHERE TEMPS RISE INTO THE UPR 50S TO MID 60S W/ DEW PTS IN THE 50S. CURRENT AREA OF CONVECTION OVER KY/TN WILL LIKELY BREAK APART WHEN IT INTERACTS W/ THE MTNS BUT MAY RE- GENERATE THIS AFTN. ONLY MINIMAL INSTABILITY BUT THERE IS DECENT SHEAR SO AN ISO STRONGER STORM IS POSSIBLE/MAIN THREAT BEING STRONG WINDS. && .SHORT TERM /6 PM THIS EVENING THROUGH MONDAY/... TONIGHT...MODELS AGREE THAT N/NE FLOW WILL OVERSPREAD THE ENTIRE CWA BY 00Z...AS SFC LOW PUSHES OFF THE NC COAST. STILL LOTS OF LOW LEVEL MOISTURE...BUT MID LEVEL DRYING FROM THE NORTH SHOULD BRING AN END TO MOST OF THE PRECIP BETWEEN 00-03Z EXCEPT IN NE NC WHERE IT LINGERS A FEW HRS LONGER. WV SATELLITE SUGGEST STRONG AREA OF MID-UPPER CONFLUENCE OVER HUDSON BAY WILL SLIDE SE...ALLOWING WITH A 1035 MB SFC HIGH TO BUILDING INTO ERN NY STATE/NEW ENGLAND. COLD AIR FILTERS SOUTH ONCE AGAIN...BUT PRETTY GOOD CONSENSUS THAT THIS WILL HOLD OFF UNTIL AFTER BULK OF PRECIP ENDS...I.E. PRECIP ENDS BEFORE PTYPE CONCERNS BECOME A MAJOR ISSUE. FOR NOW WILL MENTION POTENTIAL FOR FREEZING DRIZZLE ACRS NRN ZONES BEGINNING AFTER ABOUT 03Z. LOWS IN THE UPR 20S NORTH...UPR 30S S. SUN/SUN NIGHT...LOOKS TO BE A COLD DAY ON SUNDAY WITH NE FLOW. ONLY CONCERN WOULD BE FOR FREEZING DRIZZLE IN THE MORNING OVER CENTRAL VA...INCLUDING METRO RICHMOND AND AREAS ON NW AS LOW LEVELS REMAIN BELOW CRITICAL THRESHOLDS FOR FROZEN PRECIP. VERY DRY ALOFT HOWEVER...SO THIS WOULD BE NOTHING MORE THAN FREEZING DRIZZLE...WILL MAKE AN HWO MENTION FOR NOW. SHOULD BE WARM ENOUGH FOR JUST -RADZ BY AFTN (EXCEPT COULD BE CLOSE IN THE COLDER FAR NW ZONES. DOUBT WE`LL SEE ANY BREAKS IN THE CLOUD COVER AS LOW LEVEL INVERSION WILL BE DIFFICULT TO MIX OUT...PERHAPS A FEW PEEKS OF SUN IN THE MORNING OVER THE FAR NORTH CLOSEST TO THE SFC HIGH. BREEZY CONDITIONS ALONG THE COAST. FAVOR THE COLDER MET NUMBERS FOR HIGHS...BASED ON LIMITED MIXING AND A LOW OVC...HIGHS RANGING FROM THE UPPER 40S FAR SE VA/NE NC...MID- UPPER 30S NW ZONES. TEMPS RISE OVERNIGHT SUNDAY NIGHT...AS SFC HIGH OVER NEW ENGLAND RETREATS OFF TO THE NE...FOLLOWED BY SIGNIFICANT WARM-UP ON MON AHEAD OF THE NEXT SYSTEM. FAVOR THE WARMER MAV VALUES ON MON W/ SSW FLOW BY LATE MORNING AFTN...HIGHS GENLY IN THE UPR 50S NW (WHERE PRECIP COMES IN EARLIER) TO THE MID- UPR 60S SE. CHC TO LIKELY POPS FOR SHOWERS ALL AREAS. && .LONG TERM /MONDAY NIGHT THROUGH FRIDAY/... A SERIES OF WAVES WILL PASS NORTH OF THE FA DURING THE LONG TERM PERIOD DRAGGING COLD FRONTS AND PERIODS PRECIP THROUGH THE AREA. RAIN WILL BEGIN TO IMPACT THE AREA MONDAY AS AN UPPER LEVEL WAVE PASSES OVER NORTHERN MICHIGAN. THE ASSOCIATED COLD FRONT CROSSES THE AREA BRINGING A PERIOD OF RAIN AND A WIND SHIFT FROM THE S TO N. THE MODELS VARY A BIT WITH THE STRENGTH OF THE SYSTEM...AND HAVE LEANED TOWARD THE WEAKER ECMWF. BUT...IF THE GFS VERIFIES THERE COULD BE A COUPLE TSTMS THAT DEVELOP IN NE NC AND SE VA. BENIGN WX PREVAILS AS HIGH PRESSURE BUILDS OVER THE AREA TUESDAY NIGHT AND SLIDES OFF THE COAST BY THURSDAY EVENING. THE NEXT SYSTEM LOOKS TO IMPACT THE AREA FRIDAY MORNING AS A WARM FRONT BRINGS RAIN INTO THE AREA...FOLLOWED BY A COLD FRONT THAT WILL BRING ANOTHER ROUND OF RAIN LATE FRI/EARLY SAT. AGAIN THERE IS A BIT OF DISAGREEMENT WITH THE MODEL TIMING OF THIS EVENT. THE ECMWF PROGRESSES THE UPPER LEVEL SYSTEM EAST MUCH MORE QUICKLY THAN THE GFS. BEING THIS FAR OUT IN THE FORECAST...JUST TRIED TO BLEND THE TIMING OF THE SCENARIOS TOGETHER. EXPECT A BIT OF A ROLLER COASTER AS FAR AS TEMPS GO DURING THE PERIOD. WITH THE APPROACH THE SYSTEM MONDAY...EXPECT HIGHS IN THE MID 60S NORTH TO UPPER 60S SOUTH. AS THE FRONT CLEARS THE AREA MILDER TEMPS WILL PREVAIL WITH HIGHS IN THE MID 50S TO 60 FOR TUES AND WED. A WARMER DAY FOLLOWS ON THUR AS WINDS TURN SOUTH AHEAD OF THE NEXT FRONT. LOWS WILL BE IN THE LOW 40S TUES...FALLING TO THE LOW AND MID 30S FOR WED AND THUR...WARMING INTO THE MID 40S FOR FRI AND SAT. && .AVIATION /12Z SATURDAY THROUGH WEDNESDAY/... ONGOING LIGHT TO MOD PCPN THIS MORNING IN ASSOCIATION WITH WEAK ISENTROPIC LIFT. MVFR/TEMPO IFR CONDS ACROSS ALL BUT FAR SE TERMINALS AS OF 06Z/1A...WITH CONDITIONS EXPECTED TO DETERIORATE TO IFR BY 12Z/SAT AT NORTHERN TERMINALS AND CONTINUE THROUGHOUT THE DAY. PCPN REMAINS IN FORM OF VERY LIGHT FZRA AT RIC AND HAS BEGUN AS LGT SNOW AT SBY BUT CHANGE TO RAIN AT ALL TERMINALS IS EXPECTED BY 10Z. NE/E WINDS FRIDAY EVENING VEER TO THE S/SW LATER THIS MORNING AS A WARM FRONT LIFTS ACROSS THE AREA, BEFORE TURNING BACK TO THE NORTH LATE SATURDAY AFTN AS LOW PRESSURE TRACKS TO OUR WEST/NORTHWEST, PUSHING A COLD FRONT THROUGH THE AREA SAT AFTN/NIGHT. OUTLOOK: ALTHOUGH PCPN IS EXPECTED TO END SAT NIGHT...WIDESPREAD IFR IS FCST TO CONTINUE THROUGH SUNDAY AND PROBABLY MONDAY. A CHANCE FOR RAIN RETURNS WITH THE NEXT COLD FRONT PASSAGE ON MONDAY WITH IMPROVING CONDITIONS BEHIND THE FRONTAL PASSAGE FOR TUESDAY THROUGH MIDWEEK. && .MARINE... LATEST WX ANALYSIS/OBSERVATIONS SHOWS WARM FRONT DRAPED JUST SOUTH OF THE WATERS THIS MORNING...RESULTING IN E-SE WINDS AS OF 09Z. WINDS WILL CONTINUE TO VEER TOWARDS THE S-SW THIS MORNING AS WARM FRONT PUSHES NORTH (WHILE INCREASING IN SPEED (TO AVG 15-20 KT)) THROUGH MIDDAY. WARM FRONT WILL MEANDER JUST NORTH OF THE WATERS LATE THIS MORNING INTO THE AFTN...BEFORE BEING SHUNTED BACK S ACROSS THE WATERS THIS AFTN INTO TONIGHT AS SFC LO PRES MOVING ACROSS NC PUSHES OFFSHORE. RESULTANT WIND DIRECTION WILL VEER AROUND TO THE N-NE BEHIND THE FRONTAL PASSAGE. PRESSURE GRADIENT WILL TIGHTEN SIGNIFICANTLY AS SFC HIGH PRESSURE CURRENTLY OVER THE UPPER MIDWEST SLIDES ACROSS NORTHEAST US. THIS WILL RESULT IN WINDS RAMPING UPWARDS INTO SCA CRIT RANGE (20 TO 25 KT)...WITH HIGHEST WINDS EXPECTED AFTER 00Z/7PM TONIGHT THROUGH SUN MRNG. WINDS BEGIN TO DIMINISH AS GRADIENT SLACKENS SUN AFTN...THOUGH RMN FM THE NE. ONLY MINOR CHANGE TO SCA WAS TO RUN THROUGH SUN AFTN OVER THE BAY, AND THROUGH LATE SUNDAY NIGHT OVER THE COASTAL WATERS. WINDS BECOME LIGHT SUNDAY NIGHT INTO EARLY MONDAY AS HIGH PRESSURE CONTINUES TO BUILD OVERHEAD, BUT RAMP UPWARDS GRADUALLY MONDAY AFTN AHEAD OF THE NEXT FRONTAL SYSTEM WHICH APPROACHES FROM THE W MONDAY. WINDS WL INITIALLY BE HIGHER OVER LAND MONDAY AFTN, BUT EVENTUALLY EXPECT ANOTHER ROUND OF SCA CONDITIONS BY MONDAY NIGHT. CONDITIONS IMPROVE BACK BELOW SCA CRITERIA ON TUE AS HIGH RPESSURE REBUILDS INTO THE REGION FROM THE WEST. && .AKQ WATCHES/WARNINGS/ADVISORIES... MD...NONE. NC...NONE. VA...WINTER WEATHER ADVISORY UNTIL 10 AM EST THIS MORNING FOR VAZ048-049-062>064. MARINE...SMALL CRAFT ADVISORY FROM 6 PM THIS EVENING TO 3 PM EST SUNDAY FOR ANZ634. SMALL CRAFT ADVISORY FROM NOON TODAY TO 3 PM EST SUNDAY FOR ANZ630>633. SMALL CRAFT ADVISORY FROM 3 PM THIS AFTERNOON TO MIDNIGHT EST SUNDAY NIGHT FOR ANZ650-652-654. SMALL CRAFT ADVISORY FROM 6 PM THIS EVENING TO MIDNIGHT EST SUNDAY NIGHT FOR ANZ656-658. && $$ SYNOPSIS...LKB NEAR TERM...LKB SHORT TERM...LKB LONG TERM...DAP AVIATION...MAM MARINE...MAM
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
1038 AM EST SAT JAN 21 2012 .SYNOPSIS... A COLD FRONT WILL APPROACH FROM THE WEST TODAY AND WILL MOVE ACROSS THE COASTAL CAROLINAS LATE TONIGHT. COOL AND MOIST CONDITIONS WILL PREVAIL ON SUNDAY AS HIGH PRESSURE BUILDS FROM THE NORTH. ANOTHER COLD FRONT IS EXPECTED TO CROSS THE REGION MONDAY NIGHT. HIGH PRESSURE WILL FOLLOW TUESDAY INTO MID WEEK...WITH ANOTHER FRONTAL SYSTEM APPROACHING FROM THE WEST LATE NEXT WEEK. && .NEAR TERM /THROUGH TONIGHT/... AS OF 1000 AM SATURDAY...CONCERN TODAY REVOLVES AROUND CONVECTION POTENTIAL AHEAD OF A COLD FRONT APPROACHING FROM THE WEST. COLD FRONT CURRENTLY ANALYZED TO BE JUST WEST OF THE MTNS AT THIS TIME IS ADVANCING EAST...WITH A BAND OF PREFRONTAL SHOWERS AND TSTMS PRECEDING IT. AHEAD OF THIS BOUNDARY...ILM CWA IS FIRMLY ENTRENCHED IN THE WARM SECTOR WITH DEEP SW FLOW THROUGH THE COLUMN. ALL LOCATIONS AWAY FROM THE BRUNSWICK COUNTY COAST WERE ALREADY IN THE 60S AS OF 10 AM. MAX TEMPS WILL BE TEMPERED BY SIGNIFICANT CLOUD COVER...BUT ENOUGH BREAKS WILL ALLOW MOST LOCATIONS TO RISE TO AROUND 70 TODAY. WITHIN THIS WARM SECTOR...WHERE CLOUDS ARE BREAKING ACROSS THE UPSTATE OF SC...NUMEROUS SHOWERS ARE DEVELOPING AND ADVECTING NORTHEAST INTO THIS AREA. HAVE BUMPED POP ACCORDINGLY TO ACCOUNT FOR THIS. MAIN IMPACTS STILL EXPECTED TO OCCUR LATE THIS AFTN AND THROUGH EARLY TONIGHT. SPC CONTINUED THE SLIGHT RISK IN THE SWODY1 FOR WESTERN PORTIONS...BASICALLY CKI-MAO-MEB AND WEST WITH WIND BEING THE PRIMARY THREAT. A FEW FACTORS WORKING AGAINST A WIDESPREAD SEVERE EVENT TODAY HOWEVER...NAMELY LACK OF PARAMETERS WORKING IN CONCERT. ALTHOUGH SBCAPE WILL JUMP TO 300-500 J/KG OVER INLAND ZONES (CONTAINED WITHIN THE SLIGHT RISK)...OTHER PARAMETERS APPEAR LIMITING. 50 KTS AT 2 KFT ON LTX VWP IS ACTUALLY PROGGED TO WEAKEN SLIGHTLY...SO LLJ WILL ONLY PEAK IN THE 40-50 KT RANGE DURING CONVECTION. ALTHOUGH 0-6 KM SHEAR VECTOR WILL BE AROUND 40 KTS...FAVORING MULTICELLULAR STORM TYPE...AND ML LAPSE RATES IMPROVE ABOVE 7 C/KM...THESE ARE CONFINED MOSTLY TO EASTERN ZONES. 0-3 KM SRH SHOULD REACH 200-300 M2/S2...PRIMARILY CAUSED BY INCREASING UNIDIRECTIONAL FLOW WITH HEIGHT...BUT IS ENHANCED IN AREAS WITH LESSER INSTABILITY. SO...USING THE HRRR ENSEMBLE REFLECTIVITY AS A GUIDE...EXPECT SHOWERS TO PERSIST THROUGH THE EARLY AFTN...WITH PREFRONTAL LINE REACHING MARLBORO COUNTY BETWEEN 3P-4P...AND EXITING OFFSHORE AROUND 9P. HAVE REMOVED MENTION OF GUSTY WINDS FROM WX GRIDS AND EXPECT PRIMARILY A NON SEVERE EVENT. OF COURSE...CANNOT RULE OUT AN ISOLATED DAMAGING WIND GUST...ESPECIALLY WITHIN ANY BOWING SEGMENTS/STRUCTURES WITHIN THE LINE...BUT PRIMARY THREATS WILL BE SUB-SEVERE WIND AND SMALL HAIL. WILL OF COURSE MONITOR...IF MORE SUNSHINE BREAKS OUT THAN ANTICIPATED...THIS COULD ENHANCE THE SEVERE THREAT THIS EVE. COLD FRONT DROPS NORTH TO SOUTH TONIGHT AND SHOULD BE PUSHING THROUGH THE SOUTHERN PORTIONS OF THE CWA BY 7AM SUNDAY. WEDGING HIGH PRESSURE BEHIND THIS FRONT TRAPS RESIDUAL MOISTURE ON DECREASING N/NE WINDS...SO SHOWERS/DRIZZLE WILL PERSIST THROUGH THE NIGHT. MINS TONIGHT WILL DROP INTO THE MID 40S ACROSS THE EXTREME NORTH...TO AROUND 50 IN THE SOUTHEAST. && .SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/... AS OF 3 AM SATURDAY...HIGH PRESSURE WILL RIDGE DOWN INTO THE CAROLINAS ON SUNDAY FROM HIGH PRESSURE CENTERED OVER NORTHERN MAINE. LOOKS LIKE COLD AIR WILL WEDGE ITSELF DOWN THE LEE OF THE APPALACHIANS ON SUNDAY AS LINGERING TROUGH/FRONT WILL REMAIN SOUTH AND EAST OF LOCAL AREA. THIS SHALLOW COOL AIR WILL WORK ITS WAY IN WHILE SW FLOW ALOFT WILL ALLOW DRIER AND WARMER LAYER. OVERALL EXPECT THIS TO PRODUCE LOW CLOUDS AND DRIZZLE/LIGHT RAIN THROUGH SUNDAY. SHOULD BE AN INTERESTING TEMP FORECAST AS GFS KEEPS COLDER AIR WEDGED INLAND BUT SHOWS TEMPS CLOSER TO THE UPPER 50S ALONG THE COAST WHILE NAM SHOWS TEMPS CLOSER TO 50 TO ILM AND COASTAL AREAS FOR SUNDAY. FOR NOW...LOWERED MAX SLIGHTLY BUT WILL NOT JUMP TOTALLY ON NAM BANDWAGON JUST YET. WINDS COME BACK AROUND TO THE SOUTH AT THE SURFACE IN RETURN FLOW AHEAD OF NEXT SYSTEM APPROACHING ON SUNDAY NIGHT INTO MONDAY. A DEEPER SOUTHERLY FLOW WILL SET UP WITH A LLJ UP TO 40 KTS PUSHING MOISTURE BACK INTO AREA. PLENTY OF WAA WILL PRODUCE A RETURN TO WARMER TEMPS WITH HIGHS REACHING CLOSER TO 70 ON MONDAY. SHOULD SEE CLOUDS THROUGH THE PERIOD WITH FOG OVERNIGHT. LIGHT PCP ON SUNDAY WILL TAPER OFF BUT GREATER CHC OF RAIN SHOWERS WILL COME ON MONDAY AHEAD AND ALONG COLD FRONT. THE FRONT SHOULD MOVE THROUGH BY LATE MONDAY INTO EARLY TUESDAY. GFS SHOWS PLENTY OF DRY AIR MOVING IN BY DAYBREAK ON TUESDAY WITH PCP WATER VALUES DROPPING FROM NEAR 1.3 INCHES DOWN TO LESS THAN A HALF INCH BY TUES MORNING. && .LONG TERM /TUESDAY THROUGH FRIDAY/... AS OF 3 AM SATURDAY...SHOULD SEE A FAIRLY NICE START TO THE PERIOD WITH DEEP W-NW FLOW AND HIGH PRESSURE BUILDING IN BEHIND EXITING COLD FRONT. THIS WILL BE RELATIVELY SHORT LIVED AS PROGRESSIVE FLOW KEEPS THINGS MOVING ALONG. HIGH PRESSURE WILL SHIFT OFF SHORE AS NEXT SYSTEM MAKES ITS WAY EAST. SHOULD SEE SOME MID TO HIGH CLOUDS BACK IN THE FORECAST BY WEDNESDAY IN W-SW FLOW OVER THE TOP OF THE RIDGE ALOFT. WILL SEE SFC HIGH SHIFT OFF SHORE WITH RETURN FLOW SETTING UP ONCE AGAIN AS COLD FRONT PUSHES IN FROM THE N-NW. THIS FRONT WILL PRODUCE ANOTHER DAY OF CLOUDS AND PCP FOR THURS INTO FRI WITH POTENTIAL FOR ANOTHER LOW PRESSURE SYSTEM MOVING IN FROM THE GULF COAST BY THE WEEKEND. AS FOR TEMPS...EXPECT TO SEE A GREATER DIURNAL SWING IN A DRIER AIR MASS INITIALLY. TEMPS WILL BE INTO THE 60S DURING THE DAY BUT TUES NIGHT AND WED NIGHT WILL HAVE BETTER RADIATIONAL COOLING WITH LESS IN THE WAY OF CLOUDS AND LOWER DEWPOINTS. THEREFORE OVERNIGHT LOWS SHOULD MAKE IT DOWN TO 40 OR BELOW. AS CLOUDS AND PCP RETURN THURS AND FRI TEMPS OVERNIGHT WILL REMAIN HIGHER WITH DAYTIME HIGHS CONTINUING TO PUSH INTO THE 60S. && .AVIATION /12Z SATURDAY THROUGH WEDNESDAY/... AS OF 12Z...LIGHT RAIN NEAR LBT TO ILM WILL COME TO AN END SHORTLY AFTER 12Z LEAVING ALL TERMINALS UNDER VFR CONDITIONS. BROKEN TO OVERCAST CLOUD VFR CLOUD COVER WILL PERSIST THROUGH MUCH OF THE DAY. SOUTH-SOUTHWEST TO SOUTHWEST WINDS WINDS WITH GUSTS TO 25-28 KNOTS EXPECTED AHEAD OF AN APPROACHING COLD FRONT. FORECAST WIND TRAJECTORIES...DEWPOINTS IN THE MID 50S AND WATER TEMPERATURES IN THE LOW 50S...SUGGEST IF ANY SEA FOG DEVELOPS IT WILL REMAIN EAST OF THE CRE/MYR TERMINALS. A LINE OF CONVECTIVE SHOWERS AND POSSIBLY ISOLATED THUNDERSTORMS WILL PRECEDE THE COLD FRONT AND AFFECT THE FLO/LBT TERMINALS 20-22Z AND THE COASTAL TERMINALS BY 00-02Z. SINCE THUNDERSTORMS WILL BE ISOLATED WILL NOT INCLUDE IN TAFS. TEMPO MVFR LIKELY WITH THE SHOWERS...WITH ANY IFR TOO SHORT LIVED TO MENTION IN TAFS ATTM. SHOWERS/MVFR CONDITIONS BECOME LIKELY AS THE COLD FRONT APPROACHES THIS EVENING. POST FRONTAL IFR CEILINGS AND VISIBILITIES IN LIGHT RAIN AND DRIZZLE LIKELY MID TO LATE EVENING...EXCEPT SHORTLY AFTER MIDNIGHT AT MYR/CRE. EXTENDED OUTLOOK...POTENTIAL MVFR CIGS/ISOLATED IFR CIGS SUNDAY. ANTICIPATE VFR MONDAY THROUGH EXTENDED PERIOD WITH EXCEPTION OF POSSIBLE MVFR EARLY MONDAY MORNING. && .MARINE... NEAR TERM /THROUGH TONIGHT/... AS OF 1000 AM SATURDAY...SMALL CRAFT ADVISORY IN EFFECT FOR ALL WATERS THROUGH TONIGHT. FORECAST REMAINS ON TRACK FOR SEA HEIGHTS...WITH 41013 REPORTING 7 FT AT 10 AM...WITH 4 FT AT 41110. WINDS HAVE BECOME QUITE GUSTY AT FRYING PAN SHOALS...BUT COLD SHELF WATERS ARE KEEPING WIND GUSTS DOWN IN THE INNER 20 NM. EXPECT GUSTS TO SLOWLY INCREASE...ESPECIALLY ACROSS AMZ250 AND AMZ252...HELPING TO FORCE WIND DRIVEN WAVES UP TO 6 FT BEFORE EASING TONIGHT. A FEW WAVES NEAR THE OUTER 20 NM RANGE WILL REACH 8 FT LATE THIS AFTN. SW WINDS OF 15-25 KTS WILL PERSIST THROUGH THE FRONTAL PASSAGE TONIGHT...WHEN THEY WILL TURN TO THE NORTH AND DECREASE TO LESS THAN 15 KTS. SEAS WILL FALL IN TANDEM...BECOMING 3-4 FT WITH A NORTHERLY CHOP BY THE END OF THE PERIOD. SCATTERED SHOWERS AND THUNDERSTORMS ARE EXPECTED TO CROSS THE WATERS LATE TONIGHT CREATING LOCALLY HIGHER WINDS AND SEAS. SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/... AS OF 3 AM SATURDAY...COOL BUT LIGHTER NORTHERLY FLOW WILL SET UP OVER THE COASTAL WATERS ON SUNDAY AS COLD FRONT REMAINS JUST SOUTH AND EAST. THIS WILL ALLOW SEAS TO RELAX DOWN LESS THAN 4 FT WITH WINDS 15 KTS OR LESS. AS FLOW CONTINUES TO REMAIN PROGRESSIVE...AN INCREASING RETURN FLOW WILL SET UP ONCE AGAIN LATE SUN NIGHT INTO MON WITH WINDS INCREASING UP TO 20 KTS. THIS WILL PUSH SEAS UP AGAIN INTO THE 3 TO 5 FT RANGE AND MAY SEE A BRIEF PERIOD OF 4 TO 6 FT SEAS BORDERING SCA THRESHOLDS MON AFTERNOON AS COLD FRONT APPROACHES. EXPECT COLD FRONT TO MOVE THROUGH BY END OF PERIOD WITH DECREASING OFF SHORE FLOW SETTING UP BY TUES MORNING AND SEAS DIMINISHING. LONG TERM /TUESDAY THROUGH WEDNESDAY/... AS OF 3 AM SATURDAY...AS MENTIONED PREVIOUSLY THE MARINE COMMUNITY WILL CONTINUE TO EXPERIENCE CHANGEABLE CONDITIONS IN A PROGRESSIVE PATTERN. A MUCH LIGHTER FLOW DEVELOPS TUES INTO WED AS HIGH PRESSURE MOVES OVER THE WATERS WITH WINDS VEERING AROUND FROM NW TO NE. WITH WINDS REMAINING LESS THAN 10 KTS THROUGH MOST OF THE PERIOD...SEAS WILL DIMINISH DOWN FROM 2 TO 4 FT TUES MORNING DOWN TO LESS THAN 3 FT TUES NIGHT THROUGH WED NIGHT. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...NONE. NC...NONE. MARINE...SMALL CRAFT ADVISORY FROM 10 AM THIS MORNING TO 5 PM EST THIS AFTERNOON FOR AMZ254-256. SMALL CRAFT ADVISORY FROM 7 AM THIS MORNING TO 7 PM EST THIS EVENING FOR AMZ250-252. && $$ NEAR TERM...JDW SHORT TERM...RGZ LONG TERM...RGZ AVIATION...MRR
AREA FORECAST DISCUSSION
NWS GRAND FORKS ND
940 AM CST SAT JAN 21 2012 .DISCUSSION...FORECAST CHALLENGE CONCERNS WIND AND TEMPERATURES. WARM ADVECTION AND STIFF SE WINDS TO CONTINUE TODAY. RUC SOUNDINGS INDICATING 30-40KTS AT 925MB HOWEVER MIXED LAYER VERY SHALLOW SO NOT CONFIDENT STRONGER WINDS WILL MIX DOWN. WILL BE WINDY BUT FEELING NOW IS WINDS WILL STAY BLO ADVISORY CRITERIA. OTHERWISE CANADIAN RADARS INDICATING -SN BREAKING OUT ACROSS SOUTHERN PRAIRIE PROVINCES ON LEADING EDGE OF WARM ADVECTION. MOST LOOKS WELL NORTH OF BORDER BUT WILL NOT HURT TO MAINTAIN SLIVER OF LOW POPS ALONG BORDER. TEMPERATURES CLIMBING A LITTLE AHEAD OF SCHEDULE BUT WITH MORE CLOUDS THAN SUN TODAY FEEL MAXIMUM VALUES IN LINE. WILL MAKE SOME MINOR ADJUSTMENTS BUT OVERALL CURRENT FORECAST LOOKS GOOD. && .AVIATION... VFR CEILINGS WILL PERSIST THROUGH AT LEAST 21 UTC...AND THEN SLOWLY BEGIN TO FALL LATE THIS AFTERNOON AND EVENING AS A LOW PRESSURE SYSTEM MOVES INTO THE REGION. A SNOW/SLEET/FREEZING RAIN MIX IS POSSIBLE FOR AIRFIELDS ALONG AND WEST OF THE VALLEY AFTER 00 UTC...BUT ALL PRECIPITATION SHOULD CHANGE OVER TO SNOW AROUND SUNRISE. EXACT PRECIPITATION TIMING...PHASE AND COVERAGE IS STILL UNCERTAIN...SO MULTIPLE TAF UPDATES ARE POSSIBLE OVER THE NEXT 24 HOURS. STRONG SOUTHERLY WIND WILL DEVELOP THIS MORNING WITH AFTERNOON GUSTS UP TO 30 KTS. PATCH OF MVFR CIGS ACROSS EASTERN SD AND WILL NEED TO MONITOR NORTHWARD MOVEMENT. && .FGF WATCHES/WARNINGS/ADVISORIES... ND...NONE. MN...NONE. && $$ VOELKER
AREA FORECAST DISCUSSION...UPDATED
NWS ABERDEEN SD
725 AM CST SAT JAN 21 2012 .UPDATE... MINOR UPDATE THIS MORNING TO INCREASE CLOUD COVER FOR TODAY. LOW STRATUS DECK ADVECTING NORTHWARD ALONG THE I-29 CORRIDOR QUITE RAPIDLY THIS MORNING. 06Z RUC ALSO EXPANDS THIS AREA OF CLOUDS NORTHWESTWARD DURING THE MORNING HOURS. UPDATED 12Z AVIATION DISCUSSION BELOW. && .PREVIOUS DISCUSSION... .SHORT TERM...THROUGH MONDAY WINTER CONTINUES. WITH WIDESPREAD TEMPERATURES AROUND/BELOW ZERO THIS AM...WARM ADVECTION ALOFT WILL RESULT IN A STRONG INVERSION JUST OFF THE SURFACE. THIS...ALONG WITH A LESS THAN FAVORABLE MIXING DIRECTION WILL TRANSLATE THE 50KT LOW LEVEL JET OVER THE EASTERN CWA INTO MERELY BREEZY CONDITIONS AT THE SURFACE. GIVEN THE LIGHT POWDER...SHOULD SEE SOME BLOWING SNOW THOUGH IT IS UNLIKELY TO RESULT IN WIDESPREAD REDUCTIONS TO VISIBILITY. WARM ADVECTION AHEAD OF A CLIPPER SYSTEM WILL ONLY MAKE CONDITIONS MORE HAZARDOUS AS ANY LIGHT PRECIPITATION WITHIN THE SYSTEMS WARM SECTOR WILL RESULT IN SLEET OR FREEZING RAIN. EVEN WHERE TEMPERATURES WARM ABOVE ZERO TODAY...THE GROUND SHOULD REMAIN VERY COLD AND RESULT IN SOME ICING CONDITIONS. AS THE SYSTEM SLOWLY PROGRESSES EAST...BUFKIT PROFILES INITIALLY SHOWING INTERMITTENT LIFT/SATURATION IN THE DENDRITIC GROWTH ZONE WITH DRY/MILD LOW LEVEL AIR MAKING PTYPE DIFFICULT TO INTERPRET TRANSITIONS TO PROFILES CONDUCIVE FOR ALL SNOW. THE COLD ADVECTION RESPONSIBLE FOR THIS CHANGE OVER WILL ALSO LEAD TO STRONG WINDS WITH H85 WINDS TOPPING 60KTS...RESULT IN IN CONTINUED WINTER WEATHER IMPACTS. GOOD MIXING INITIALLY MEANS HIGHS SUNDAY ABOVE FREEZING...WITH TEMPERATURES FALLING THROUGH THE REST OF THE DAY. .LONG TERM...MONDAY NIGHT THROUGH FRIDAY NIGHT FORECAST PERIOD BEGINS WITH AN ELONGATED NORTH TO SOUTH SURFACE HIGH PRESSURE OVER THE CWA MONDAY NIGHT. THIS SFC HIGH IS PROGGED TO GRADUALLY SLIDE SEWD ON TUESDAY. GLOBAL MODELS THEN DROP A WEAK CLIPPER SHORT- WAVE TROUGH SEWD THROUGH ERN ND WEDNESDAY. ANOTHER CLIPPER WAVE IS THEN FORECAST TO MOVE EWD THROUGH CENTRAL ND THURSDAY. LATEST MODEL RUNS ARE DRY WITH BOTH OF THE UPPER TROUGH AND ASSOCIATED WEAK COLD FRONTAL PASSAGES...KEEPING SNOW CHANCES IN NORTH DAKOTA. ALL IN ALL A DRY WEEK APPEARS IN STORE FOR THE CWA WITH TEMPERATURES ABOUT 10 DEGREES ABOVE SEASONAL AVERAGES FOR LATE JANUARY. && .AVIATION... 12Z TAFS FOR THE KABR...KATY...KPIR AND KMBG TERMINALS AN AREA OF MVFR CIGS WILL CONTINUE TO MOVE NORTH ALONG THE I-29 CORRIDOR THIS MORNING...IMPACTING KATY. THE CIGS WILL ALSO EXPAND NORTHWESTWARD DURING THE MORNING HOURS. SOUTH WINDS WILL BE ON THE INCREASE AROUND MID-MORNING WITH WINDS GUSTING TO ABOUT 30 KTS AT ALL TAF SITES. LOW LEVEL WIND SHEAR IS EXPECTED AT KABR AND KATY FROM APPROXIMATELY MID MORNING THROUGH THE AFTERNOON. THE STRONG SOUTH WINDS WILL SUBSIDE DURING THE EVENING. AS AN UPPER LEVEL TROUGH AND SFC COLD FRONT APPROACH THE REGION TONIGHT...A MIXED BAG OF PRECIPITATION IS EXPECTED OVERNIGHT WITH -FZDZ/-PL/-SN ALONG WITH WDSPRD IFR/LIFR CIGS AND MVFR VSBYS. && .ABR WATCHES/WARNINGS/ADVISORIES... SD...WINTER WEATHER ADVISORY FROM 6 PM CST /5 PM MST/ THIS EVENING TO MIDNIGHT CST /11 PM MST/ SUNDAY NIGHT FOR BROWN-CAMPBELL- CORSON-DEWEY-EDMUNDS-FAULK-MCPHERSON-POTTER-WALWORTH. WINTER WEATHER ADVISORY FROM MIDNIGHT TONIGHT TO MIDNIGHT CST SUNDAY NIGHT FOR CLARK-CODINGTON-DAY-DEUEL-GRANT-HAMLIN- MARSHALL-ROBERTS-SPINK. MN...WINTER WEATHER ADVISORY FROM MIDNIGHT TONIGHT TO MIDNIGHT CST SUNDAY NIGHT FOR BIG STONE-TRAVERSE. && $$ UPDATE...CHURCH SHORT TERM...CONNELLY LONG TERM...CHURCH AVIATION...CHURCH WEATHER.GOV/ABERDEEN
AREA FORECAST DISCUSSION FOR SOUTHEAST SD/SOUTHWEST MN/NORTHWEST IA
NWS SIOUX FALLS SD
521 AM CST SAT JAN 21 2012 .DISCUSSION.../ISSUED AT 300 AM CST/ MAIN CONCERN FOR TODAY WILL BE CLOUD COVER AND BLOWING SNOW. STRATUS IS RETURNING NORTH THIS MORNING BETWEEN JAMES AND BIG SIOUX RIVER WITH RETURN LOW LEVEL SELY FLOW. SO WUD EXPECT THIS STRATUS TO CONTINUE TO ADVECT NORTH UNDER LOW LEVEL INVERSION AND RUC SEEMS TO HANDLE THIS LOW LEVEL MOISTURE FAIRLY WELL SO WILL KEEP FAIRLY HIGH CLOUD COVER THOSE AREA THIS MORNING WITH THE INVERSION RISING A BIT BY AFTERNOON WHICH SHOULD HELP SCOUR IT OUT A BIT. NEXT IS THE INCREASING SOUTHERLY WINDS AHEAD OF NEXT WAVE THAT SHOULD GUST TO 30 TO 35 MPH LATER THIS MORNING AND AFTERNOON WHICH SHOULD CREATE AREAS OF BLOWING SNOW. WILL NOT ISSUE ANY ADVISORY AS HARD TO CREATE WIDESPREAD BLOWING PROBLEMS WHEN LOW LEVEL MOISTURE INCREASES OVER FRESH SNOW COVER. SO FOR NOW WILL JUST MENTION AREAS OF BLOWING SNOW THROUGH THE EVENING HOURS. HIGH TEMPERATURES TODAY WILL AGAIN STRUGGLE ACROSS THE EAST BUT SHOULD WARM CLOSER TO NORMAL ACROSS THE WEST. WITH STOUT SOUTHERLY FLOW TONIGHT...NOT EXPECTING TEMPERATURES TO FALL MUCH AND SHOULD ACTUALLY RISE A BIT...ESPECIALLY EAST. SYSTEM COMING OUT LATE TONIGHT AND SUNDAY A BIT SLOWER. STILL CONTINUES TO SHOW A SPLIT FLOW SYSTEM WITH ONE SYSTEM LIFTING UP ACROSS NORTHWEST CWA AND SOUTHERN WAVE MOVING NORTHEAST ACROSS CENTRAL PLAINS AND THEN PHASING EAST OF I29 SUNDAY NIGHT. WITH SLOWER SPEED THERE MAY NOT BE MUCH IF ANY PRECIPITATION ACROSS WESTERN CWA TONIGHT EXCEPT POSSIBLY FAR WESTERN CWA AFTER 09Z. WARM ENOUGH ALOFT THAT ANY PRECIPITATION WOULD BE FREEZING RAIN AND NOT SNOW SO WILL REMOVE MENTION OF SNOW LATE TONIGHT. AMOUNTS IF ANY WILL BE VERY LIGHT AND WILL NOT ISSUE ANY HEADLINE. ON SUNDAY...SOUTHERN WAVE MAY CLIP NORTHWEST IOWA DURING THE AFTERNOON AND WILL KEEP 40% POPS THERE AND LIKELY POPS ACROSS FAR NORTHWEST CWA WITH NORTHERN WAVE. IN BETWEEN WILL KEEP POPS RELATIVELY LOW IN THE 30% RANGE. DOUBT WE WILL SEE ANY FREEZING RAIN BY LATER SUNDAY MORNING AND AFTERNOON AS AIRMASS COOLS AND ANYTHING THAT DOES FALL WILL BE SNOW. SO WILL REMOVE ANY MENTION OF RAIN WEST AND WILL ALSO LOWER HIGH TEMPERATURES DUE TO THE COOLING OF THE COLUMN WITH THESE FEATURES. COULD SEE AN INCH OR TWO OF SNOW IN THE JAMES VALLEY SUNDAY AFTERNOON. GUSTY NORTHWEST WINDS WILL DEVELOP SUNDAY AFTERNOON ACROSS THE WESTERN CWA AS SURFACE TROF MOVES EAST WITH COLD AIR ADVECTION BRINGING IN STRONGER WINDS. SO COULD SEE SOME MORE BLOWING SNOW ACROSS THE WEST. SUNDAY NIGHT WILL SEE GUSTY NORTHWEST WINDS AND AREAS OF BLOWING SNOW WITH SOME LIGHT SNOW ACROSS THE CWA WITH PHASING UPPER TROF. NOT EXPECTING MUCH IN THE WAY OF ACCUMULATIONS WITH LESS THAN ONE INCH EXPECTED. ANOTHER CHILLY DAY ON MONDAY BEHIND THE WAVE WITH BELOW NORMAL TEMPERATURES EAST WITH HIGHS IN THE TEENS TO LOWER 20S. SHOULD BE A BIT WARMER WEST WITH HIGHS IN THE 20S. SURFACE HIGH WILL SETTLE ACROSS THE CWA MONDAY NIGHT...AND WITH LIGHT WINDS AND FRESH SNOW COVER...WITH GO 5 TO 10 DEGREES COLDER THAN CONSALL AND CONSRAW WHICH ARE NOT HANDLING SNOW COVER WELL AS EVIDENT BY THE VERY COLD TEMPERATURES THIS MORNING ACROSS MUCH OF CWA. WOULD NOT BE SUPRISED IF A FEW LOCATIONS ACROSS THE EAST DROP BELOW ZERO EARLY TUESDAY MORNING. SHOULD BE WARMER ACROSS THE CWA TUESDAY THROUGH FRIDAY WITH A MORE ZONAL FLOW...BUT SNOW COVER WILL HAVE A HUGE IMPACT...ESPECIALLY EAST WHERE SNOW COVER IS DEEPER AND WILL NOT MELT OFF. SO MAY AT BEST SEE HIGHS NEAR 30 ACROSS THE EAST DURING THIS TIME PERIOD...WHILE WESTERN CWA WILL HAVE A BETTER CHANCE TO MELT AWAY SOME OF THE SNOW AND APPROACH 40 FOR DAYTIME HIGHS...ESPECIALLY SOUTHWEST CWA. DOESN`T LOOK LIKE MUCH THREAT FOR ANY PRECIPITATION AFTER SUNDAY AND WILL BASICALLY KEEP CWA DRY EXPECT FOR A VERY SLIGHT CHANCE OF LIGHT SNOW TUESDAY NIGHT EAST OF I29 WITH VERY WEAK WAVE. && .AVIATION.../FOR THE 12Z TAF ISSUANCE/ AREA OF MVFR CIGS ACROSS SOUTHEAST SOUTH DAKOTA WILL MOVE ENE THIS MORNING AS SW WINDS DEVELOP ABOVE THE SURFACE. BASED UPON CURRENT MOVEMENT...LOW CLOUDS SHOULD MOVE EAST OF KHON AND KFSD BY 14Z AND KSUX BY 15Z. OTHERWISE...WINDS EXPECTED TO REALLY INCREASE THIS MORNING WITH WINDS GUSTING OVER 30 KTS EXPECTED IN MOST AREAS BY EARLY THIS AFTERNOON. WITH FRESH SNOW COVER EXPECT SOME BLOWING SNOW BUT THE BOUNDARY LAYER IS RELATIVELY STABLE WITH THE WARM AIR ADVECTION DEVELOPING SO THAT REALLY SHOULD LIMIT THE REDUCED VISIBILITIES TO ONLY A COUPLE OF HOURS THIS AFTERNOON WHEN WINDS ARE MOST LIKELY TO GUST OVER 30 KTS. WINDS WILL DECREASE A LITTLE TONIGHT AND THE MID AND UPPER CLOUDS WILL MOVE OVER. WITH A STRONG PV ANOMALY MOVING OVER THE 850 MB BOUNDARY IN CENTRAL SD LATE TONIGHT...DID BRING MVFR CIGS BACK INTO HURON LATE TONIGHT. THERE IS A LOW CHANCE OF FREEZING RAIN IN HURON AFTER 09Z BUT THE PROBABILITY IS LOW ENOUGH THAT DID NOT INCLUDE IN TAF AT THIS TIME. HOWEVER...SNOW...POSSIBLY MIXED WITH FREEZING RAIN...ARE MORE LIKELY LATE SUNDAY MORNING AND SUNDAY AFTERNOON ACROSS MOST OF SE SD AND WILL LIKELY IMPACT CIGS AND VSBYS./SCHUMACHER && .FSD WATCHES/WARNINGS/ADVISORIES... SD...NONE. MN...NONE. IA...NONE. NE...NONE. && $$
AREA FORECAST DISCUSSION
NWS ALBANY NY
225 PM EST SAT JAN 21 2012 .SYNOPSIS... A HIGH PRESSURE SYSTEM WILL BUILD INTO THE NORTHEAST TONIGHT AND SUNDAY...BRINGING FAIR BUT COLD WEATHER. ON MONDAY...A POWERFUL STORM WILL MOVE FROM THE UPPER GREAT LAKES REGION INTO WESTERN QUEBEC...LIKELY BRINGING MIXED PRECIPITATION CHANGING TO RAIN. && .NEAR TERM /THROUGH TONIGHT/... AS OF 200 PM...SNOW HAS ENDED OR BECOME VERY LIGHT ACROSS THE ADVISORY AREA (ULSTER...DUTCHESS...LITCHFIELD COUNTIES)...SO CANCELLED THE ADVISORY JUST AFTER 200 PM. ONLY DECREASING CHANCE POPS FORECAST FOR THE REST OF THE AFTERNOON. TEMPS HAVE ALSO BEEN ADJUSTED DOWNWARD SINCE IT APPEARS THAT ANY CLEARING THAT OCCURS WILL LIKELY ARRIVE TO LATE FOR THE SUN TO HAVE ANY IMPACT ON TEMPS. ****PREVIOUS DISCUSSION**** SNOW WINDING DOWN ACROSS MOST OF THE FORECAST AREA. BEST LIFT WITH WARM ADVECTION AND SEEDER FEEDER PROCESS OVER SOUTHEAST. THIS WILL GRADUALLY MOVE EAST NEXT FEW HOURS. SOME CLEARING NOTED OVER FINGER LAKES/SOUTHERN ONTARIO AND THIS IS GRADUALLY MOVING IN. LOW CLOUDS HANGING TOUGH OVER MOST OF FORECAST AREA. CLOUD TOP TEMPS COLD ENOUGH FOR SNOW. WEAK WARM ADVECTION WILL CAUSE SOME LIGHT SNOW INTO AFTERNOON BUT LITTLE ACCUMULATION EXPECTED OUTSIDE FAR SOUTHEAST PART OF FORECAST AREA. TEMPS STILL NOT BUDGING MUCH. CURRENT FORECAST MAX AT ALBANY 24F TODAY BUT THIS MAY BE OPTIMISTIC IF CLOUDS DONT BREAK UP TILL LATE IN DAY. LATEST UPDATE TO MODIFY CLOUDS/POPS/WX/WINDS BASED ON OBS/RADAR AND 12Z NAM. PREVIOUS... WEAK MIDLEVEL SYSTEM MOVING FROM WEST TO EAST. SNOW HAS ENDED OR GREATLY DIMINISHED OVER NORTHWEST PART OF AREA. LATEST RUC ANALYSIS SHOWS H850 WARM ADVECTION CONTINUING ACROSS THE AREA AND VAD WIND PROFILE CONFIRMS THIS. SNOW SEEMS TO BE ENDING ONCE MID/HIGH LEVEL CLOUDS MOVE AWAY AND SEEDER FEEDER MECHANISM DIMINISHES. CLOUD TOPS COOLING OVER SOUTHEAST PART OF FORECAST AREA INDICATING ONE MORE BAND OF MODERATE SNOW POSSIBLE THERE LATE THIS MORNING BEFORE HIGHER CLOUDS MOVE OFF AND SNOW DIMINISHES. RECENT UPDATE TO ADJUST POPS WHERE SNOW HAS DIMINISHED OR ENDED. ALSO ADJUSTED MAX TEMPS DOWNWARD 2 DEGREES VALLEYS AND 3-5 DEGREES MOUNTAINS AS OBS SHOW TEMPS NOT MOVING THIS MORNING. && .SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/... WE BEGIN THIS SHORT TERM PORTION OF THE FORECAST ON A TRANQUIL NOTE WITH A 1035MB SURFACE HIGH SLIDING ACROSS THE EASTERN GREAT LAKES REGIONS AND NEW ENGLAND THROUGH THE DAY. FAIRLY DRY BELOW 500MB TO KEEP POPS AT ZERO AND SKIES PT-MOSUNNY. TEMPERATURES WILL BE SEASONABLE FOR THIS TIME OF THE YEAR WITH MAINLY 20S FOR THE TERRAIN AND LOWER 30S FOR THE VALLEY FLOOR. MEANWHILE...A POWERFUL SHORT WAVE COINCIDING WITH 150KT UPPER LEVEL JET WAS COMING ASHORE ACROSS CALIFORNIA. THIS SYSTEM IS FORECAST BY THE NCEP MODEL SUITE TO IMPACT THE 4-CORNERS REGION AND EJECT OUT ONTO THE CENTRAL-SOUTHERN PLAINS SUNDAY INTO MONDAY. A POWERFUL SURFACE CYCLONE WILL DEVELOP OVER THE MID-LOWER MISSISSIPPI RIVER VALLEY AND TRACK INTO THE CENTRAL GREAT LAKES REGION THROUGH MONDAY. THE MAIN IMPACT FOR OUR REGION WILL BE AN INCREASE IN CLOUD COVER AND A STRENGTHEN SOUTHERLY WIND. HOWEVER...ISSUES ARISE OVERNIGHT SUNDAY INTO MONDAY MORNING FOR THE REGION. A CLOSER EXAMINATION OF BUFKIT AND HOURLY BUFR PROFILES FROM THE MODEL SUITES THIS MORNING ALL SUGGEST A RAPID INCREASE IN LOWER LEVEL MOISTURE FROM SOUTH TO NORTH. COMBINE THAT WITH THE WIND MAGNITUDE INCREASE AND LOW LEVEL SHEAR FOR DRIZZLE FORMATION SINCE ICE NUCLEI IS NOT EXPECTED IN THE COLUMN WITH THE HEIGHT OF THE MOISTURE PROFILES STAYING BELOW THE -10C THROUGH AT LEAST 15Z MONDAY. DUE TO SEASONABLE TEMPERATURES EXPECTED ON SUNDAY...AND SOME PARTIAL CLEAR SKIES SUNDAY EVENING...OVERNIGHT SURFACE TEMPERATURES ARE EXPECTED TO DROP BACK INTO THE TEENS ACROSS THE DACKS AND LOW-MID 20S ELSEWHERE. THIS SEEMS TO SUGGEST THAT ANY DRIZZLE FORMATION WILL FREEZE ON CONTACT. TEMPERATURES ARE EXPECTED TO CLIMB ABOVE FREEZING ALONG THE HEELS OF THE STRENGTHEN SOUTHERLY FLOW BY NOON MONDAY WHERE WE WILL REMOVE THE MENTION OF FROZEN DRIZZLE/RAIN. MONDAY AFTERNOON...AN INCREASE IN LOW LEVEL WARM ADVECTION ALONG WITH THE APPROACH OF THE FRONTAL BOUNDARY WILL KEEP POPS QUITE HIGH FOR PERIODS OF RAIN/SHOWERS. THERE ARE SOME SUBTLE HINTS THAT THUNDER COULD BE A POSSIBILITY SOUTH OF THE CAPITAL REGION WITH SHOWALTER INDICES DROPPING BACK TO NEAR 1C AND SLIGHTLY FAVORABLE MID LEVEL LAPSE RATES. WE WILL CONTINUE TO MONITOR AND NOT MENTION IN THE FORECAST/GRIDS. HIGH TEMPERATURES COULD EXCEED 40F FOR THE MAJORITY OF THE REGION. THE FRONT AND ASSOCIATED MOISTURE TRACK QUICKLY TO OUR NORTHEAST WITH A DECREASE IN POPS. HOWEVER...WITH A NEAR VERTICALLY STACKED LOW OVER THE GREAT LAKES REGION AND COLD ADVECTION...LAKE ONTARIO CONTRIBUTION IS EXPECTED TO INCREASE. DELTA T/S ARE ONLY EXPECTED TO REMAIN MARGINAL SO WE WILL KEEP POPS FOR PORTIONS OF THE DACKS IN THE 30% THRESHOLDS FOR SNOW SHOWERS. && .LONG TERM /TUESDAY THROUGH FRIDAY/... THE AFOREMENTIONED LAKE EFFECT ACTIVITY COULD STILL BE IMPACTING PORTIONS OF THE DACKS WITH A WEST-SOUTHWEST BOUNDARY LAYER WINDS AROUND THE PERIPHERY OF THE SLOWLY DEPARTING UPPER LOW. OTHERWISE...BUILDING SURFACE PRESSURES ARE EXPECTED TUESDAY THROUGH WEDNESDAY. A WEAK MID LEVEL IMPULSE APPROACHES LATE WEDNESDAY AS THE MAIN IMPACT SHOULD BE FROM AN INCREASE IN HIGH- MID LEVEL MOISTURE. THURSDAY THRU FRIDAY...CONSIDERABLE UNCERTAINTY REMAINS AS THE GFS REMAINS THE MOST PROGRESSIVE AND THE ECMWF A BIT MORE PRONOUNCED WITH RESPECT TO APPALACHIANS STORM SYSTEM THAT COULD IMPACT THE REGION THURSDAY NIGHT INTO FRIDAY. ENSEMBLES FROM THE GFS OFFER A WIDE VARIETY OF SOLUTIONS WITH A FEW CLUSTERS EVEN STRONGER THAN THE ECMWF AND FURTHER WEST. FOR NOW...A LOW CONFIDENCE FORECAST FOR THE END OF THIS WEEK. && .AVIATION /18Z SATURDAY THROUGH WEDNESDAY/... SNOW WAS PRETTY MUCH ENDED AT KALB. KGFL WAS EXPERIENCING A PLUME OF LIKELY WIND CONVERGENCE -SN/-SHSN EMANATING FROM THE TUG HILL AREA. HAVE GONE WITH JUST A ONE-HOUR TAF ONSET TEMPO GROUP THERE FOR IFR VSBY IN -SN AS THIS FEATURE WILL WEAKEN AS A HIGH PRESSURE RIDGE BUILDS IN THROUGH THIS EVENING. OTRW...BOTH KGFL AND KALB WILL HANG ONTO MVFR CLOUDS FOR AWHILE. AT KPOU...TIMING OF ACTIVITY PULLOUT IS SOMEWHAT UNCERTAIN. HAVE IT ENDING AT 22Z. LIKE KGFL... HAVE GIVEN THEM A ONE-HOUR ONSET TEMPO OF IFR VSBY IN -SN TO REFLECT MOST RECENT SCENARIO...BUT UNLIKE KGFL...A DIFFERENT MECHANISM. SUBSIDENCE HIGH PRESSURE ENHANCES OVER THE AIRPORTS THIS EVENING. DEPARTING LOW IS NOT EXPECTED TO STRENGTHEN AS THIS OCCURS...SO GRADUAL CLEARING OF ALL THE LOW AND MID LEVEL CLOUDS IS EXPECTED THROUGH THE NIGHT WHILE WINDS DIMINISH. HIGH CLOUDINESS IS EXPECTED TO MOVE IN WELL AHEAD OF THE NEXT SYSTEM...BUT SHOULD REMAIN THIN. GIVEN THIS SCENARIO...WINDS WILL NOT BE OF GREAT CONCERN...WITH NEARLY CALM SURFACE CONDITIONS EXPECTED ON SUNDAY. SOME LOW- TO MID-LEVEL WIND ENHANCEMENT WILL OCCUR...BUT THIS WILL FALL WELL SHORT OF PRODUCING ANY WIND SHEAR ISSUES. TEMPERATURES OF GROUND AND DRY AIR REMAINING QUITE COLD OVERNIGHT WILL KEEP FOG CLEAN OUT OF THE PICTURE. OUTLOOK... SUN PM...VFR...NO SIG WX. MON AM...MAINLY VFR...CHC -FZDZ. MON AFTN-EVENING...MVFR/IFR RA LIKELY MON NGT-WED...VFR...NO SIG WX. && .HYDROLOGY... NO MAJOR PROBLEMS ARE EXPECTED ON THE MAIN STEM RIVERS THROUGH NEXT FRIDAY. ANY PRECIPITATION WHICH FALLS THROUGH THIS WEEKEND WILL BE SNOW. MONDAY MAY BRING SOME LIGHT MIXED PRECIPITATION EARLY AND 0.25" TO 0.50" OF RAIN DURING THE AFTERNOON. ICE FORMATION ON BODIES OF WATER IS EXPECTED TO INCREASE AGAIN THROUGH THE WEEKEND AS COLD AIR WILL BE IN PLACE ACROSS THE REGION. TEMPS WILL BEGIN RISING LATE SUNDAY AND MONDAY...ONLY COOLING TO NEAR OR SLIGHTLY ABOVE NORMAL NEXT WEEK. FOR DETAILS ON SPECIFIC AREA RIVERS AND LAKES...INCLUDING OBSERVED AND FORECAST RIVER STAGES AND LAKE ELEVATIONS...PLEASE VISIT THE ADVANCED HYDROLOGIC PREDICTION SERVICE /AHPS/ GRAPHS ON OUR WEBSITE. && .ALY WATCHES/WARNINGS/ADVISORIES... CT...WINTER WEATHER ADVISORY UNTIL 3 PM EST THIS AFTERNOON FOR CTZ001-013. NY...WINTER WEATHER ADVISORY UNTIL 3 PM EST THIS AFTERNOON FOR NYZ063>066. MA...NONE. VT...NONE. && $$ SYNOPSIS...GJM/SNYDER/SND NEAR TERM...GJM/SND SHORT TERM...BGM LONG TERM...BGM AVIATION...ELH HYDROLOGY...BGM
AREA FORECAST DISCUSSION
NWS ALBANY NY
1252 PM EST SAT JAN 21 2012 .SYNOPSIS... WEAK LOW PRESSURE WILL TRACK OFF THE NEW JERSEY COAST TODAY AND BRING SNOW TO THE AREA. A HIGH PRESSURE SYSTEM WILL BUILD INTO THE NORTHEAST TONIGHT AND SUNDAY BRINGING FAIR WEATHER. ON MONDAY...A POWERFUL STORM MOVES FROM THE UPPER GREAT LAKES INTO WESTERN QUEBEC...LIKELY BRINGING MIXED PRECIPITATION CHANGING TO RAIN. && .NEAR TERM /THROUGH TONIGHT/... SNOW WINDING DOWN ACROSS MOST OF THE FORECAST AREA. BEST LIFT WITH WARM ADVECTION AND SEEDER FEEDER PROCESS OVER SOUTHEAST. THIS WILL GRADUALLY MOVE EAST NEXT FEW HOURS. SOME CLEARING NOTED OVER FINGER LAKES/SOUTHERN ONTARIO AND THIS IS GRADUALLY MOVING IN. LOW CLOUDS HANGING TOUGH OVER MOST OF FORECAST AREA. CLOUD TOP TEMPS COLD ENOUGH FOR SNOW. WEAK WARM ADVECTION WILL CAUSE SOME LIGHT SNOW INTO AFTERNOON BUT LITTLE ACCUMULATION EXPECTED OUTSIDE FAR SOUTHEAST PART OF FORECAST AREA. TEMPS STILL NOT BUDGING MUCH. CURRENT FORECAST MAX AT ALBANY 24F TODAY BUT THIS MAY BE OPTIMISTIC IF CLOUDS DONT BREAK UP TILL LATE IN DAY. LATEST UPDATE TO MODIFY CLOUDS/POPS/WX/WINDS BASED ON OBS/RADAR AND 12Z NAM. PREVIOUS... WEAK MIDLEVEL SYSTEM MOVING FROM WEST TO EAST. SNOW HAS ENDED OR GREATLY DIMINISHED OVER NORTHWEST PART OF AREA. LATEST RUC ANALYSIS SHOWS H850 WARM ADVECTION CONTINUING ACROSS THE AREA AND VAD WIND PROFILE CONFIRMS THIS. SNOW SEEMS TO BE ENDING ONCE MID/HIGH LEVEL CLOUDS MOVE AWAY AND SEEDER FEEDER MECHANISM DIMINISHES. CLOUD TOPS COOLING OVER SOUTHEAST PART OF FORECAST AREA INDICATING ONE MORE BAND OF MODERATE SNOW POSSIBLE THERE LATE THIS MORNING BEFORE HIGHER CLOUDS MOVE OFF AND SNOW DIMINISHES. RECENT UPDATE TO ADJUST POPS WHERE SNOW HAS DIMINISHED OR ENDED. ALSO ADJUSTED MAX TEMPS DOWNWARD 2 DEGREES VALLEYS AND 3-5 DEGREES MOUNTAINS AS OBS SHOW TEMPS NOT MOVING THIS MORNING. && .SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/... WE BEGIN THIS SHORT TERM PORTION OF THE FORECAST ON A TRANQUIL NOTE WITH A 1035MB SURFACE HIGH SLIDING ACROSS THE EASTERN GREAT LAKES REGIONS AND NEW ENGLAND THROUGH THE DAY. FAIRLY DRY BELOW 500MB TO KEEP POPS AT ZERO AND SKIES PT-MOSUNNY. TEMPERATURES WILL BE SEASONABLE FOR THIS TIME OF THE YEAR WITH MAINLY 20S FOR THE TERRAIN AND LOWER 30S FOR THE VALLEY FLOOR. MEANWHILE...A POWERFUL SHORT WAVE COINCIDING WITH 150KT UPPER LEVEL JET WAS COMING ASHORE ACROSS CALIFORNIA. THIS SYSTEM IS FORECAST BY THE NCEP MODEL SUITE TO IMPACT THE 4-CORNERS REGION AND EJECT OUT ONTO THE CENTRAL-SOUTHERN PLAINS SUNDAY INTO MONDAY. A POWERFUL SURFACE CYCLONE WILL DEVELOP OVER THE MID-LOWER MISSISSIPPI RIVER VALLEY AND TRACK INTO THE CENTRAL GREAT LAKES REGION THROUGH MONDAY. THE MAIN IMPACT FOR OUR REGION WILL BE AN INCREASE IN CLOUD COVER AND A STRENGTHEN SOUTHERLY WIND. HOWEVER...ISSUES ARISE OVERNIGHT SUNDAY INTO MONDAY MORNING FOR THE REGION. A CLOSER EXAMINATION OF BUFKIT AND HOURLY BUFR PROFILES FROM THE MODEL SUITES THIS MORNING ALL SUGGEST A RAPID INCREASE IN LOWER LEVEL MOISTURE FROM SOUTH TO NORTH. COMBINE THAT WITH THE WIND MAGNITUDE INCREASE AND LOW LEVEL SHEAR FOR DRIZZLE FORMATION SINCE ICE NUCLEI IS NOT EXPECTED IN THE COLUMN WITH THE HEIGHT OF THE MOISTURE PROFILES STAYING BELOW THE -10C THROUGH AT LEAST 15Z MONDAY. DUE TO SEASONABLE TEMPERATURES EXPECTED ON SUNDAY...AND SOME PARTIAL CLEAR SKIES SUNDAY EVENING...OVERNIGHT SURFACE TEMPERATURES ARE EXPECTED TO DROP BACK INTO THE TEENS ACROSS THE DACKS AND LOW-MID 20S ELSEWHERE. THIS SEEMS TO SUGGEST THAT ANY DRIZZLE FORMATION WILL FREEZE ON CONTACT. TEMPERATURES ARE EXPECTED TO CLIMB ABOVE FREEZING ALONG THE HEELS OF THE STRENGTHEN SOUTHERLY FLOW BY NOON MONDAY WHERE WE WILL REMOVE THE MENTION OF FROZEN DRIZZLE/RAIN. MONDAY AFTERNOON...AN INCREASE IN LOW LEVEL WARM ADVECTION ALONG WITH THE APPROACH OF THE FRONTAL BOUNDARY WILL KEEP POPS QUITE HIGH FOR PERIODS OF RAIN/SHOWERS. THERE ARE SOME SUBTLE HINTS THAT THUNDER COULD BE A POSSIBILITY SOUTH OF THE CAPITAL REGION WITH SHOWALTER INDICES DROPPING BACK TO NEAR 1C AND SLIGHTLY FAVORABLE MID LEVEL LAPSE RATES. WE WILL CONTINUE TO MONITOR AND NOT MENTION IN THE FORECAST/GRIDS. HIGH TEMPERATURES COULD EXCEED 40F FOR THE MAJORITY OF THE REGION. THE FRONT AND ASSOCIATED MOISTURE TRACK QUICKLY TO OUR NORTHEAST WITH A DECREASE IN POPS. HOWEVER...WITH A NEAR VERTICALLY STACKED LOW OVER THE GREAT LAKES REGION AND COLD ADVECTION...LAKE ONTARIO CONTRIBUTION IS EXPECTED TO INCREASE. DELTA T/S ARE ONLY EXPECTED TO REMAIN MARGINAL SO WE WILL KEEP POPS FOR PORTIONS OF THE DACKS IN THE 30% THRESHOLDS FOR SNOW SHOWERS. && .LONG TERM /TUESDAY THROUGH FRIDAY/... THE AFOREMENTIONED LAKE EFFECT ACTIVITY COULD STILL BE IMPACTING PORTIONS OF THE DACKS WITH A WEST-SOUTHWEST BOUNDARY LAYER WINDS AROUND THE PERIPHERY OF THE SLOWLY DEPARTING UPPER LOW. OTHERWISE...BUILDING SURFACE PRESSURES ARE EXPECTED TUESDAY THROUGH WEDNESDAY. A WEAK MID LEVEL IMPULSE APPROACHES LATE WEDNESDAY AS THE MAIN IMPACT SHOULD BE FROM AN INCREASE IN HIGH- MID LEVEL MOISTURE. THURSDAY THRU FRIDAY...CONSIDERABLE UNCERTAINTY REMAINS AS THE GFS REMAINS THE MOST PROGRESSIVE AND THE ECMWF A BIT MORE PRONOUNCED WITH RESPECT TO APPALACHIANS STORM SYSTEM THAT COULD IMPACT THE REGION THURSDAY NIGHT INTO FRIDAY. ENSEMBLES FROM THE GFS OFFER A WIDE VARIETY OF SOLUTIONS WITH A FEW CLUSTERS EVEN STRONGER THAN THE ECMWF AND FURTHER WEST. FOR NOW...A LOW CONFIDENCE FORECAST FOR THE END OF THIS WEEK. && .AVIATION /18Z SATURDAY THROUGH WEDNESDAY/... SNOW WAS PRETTY MUCH ENDED AT KALB. KGFL WAS EXPERIENCING A PLUME OF LIKELY WIND CONVERGENCE -SN/-SHSN EMANATING FROM THE TUG HILL AREA. HAVE GONE WITH JUST A ONE-HOUR TAF ONSET TEMPO GROUP THERE FOR IFR VSBY IN -SN AS THIS FEATURE WILL WEAKEN AS A HIGH PRESSURE RIDGE BUILDS IN THROUGH THIS EVENING. OTRW...BOTH KGFL AND KALB WILL HANG ONTO MVFR CLOUDS FOR AWHILE. AT KPOU...TIMING OF ACTIVITY PULLOUT IS SOMEWHAT UNCERTAIN. HAVE IT ENDING AT 22Z. LIKE KGFL... HAVE GIVEN THEM A ONE-HOUR ONSET TEMPO OF IFR VSBY IN -SN TO REFLECT MOST RECENT SCENARIO...BUT UNLIKE KGFL...A DIFFERENT MECHANISM. SUBSIDENCE HIGH PRESSURE ENHANCES OVER THE AIRPORTS THIS EVENING. DEPARTING LOW IS NOT EXPECTED TO STRENGTHEN AS THIS OCCURS...SO GRADUAL CLEARING OF ALL THE LOW AND MID LEVEL CLOUDS IS EXPECTED THROUGH THE NIGHT WHILE WINDS DIMINISH. HIGH CLOUDINESS IS EXPECTED TO MOVE IN WELL AHEAD OF THE NEXT SYSTEM...BUT SHOULD REMAIN THIN. GIVEN THIS SCENARIO...WINDS WILL NOT BE OF GREAT CONCERN...WITH NEARLY CALM SURFACE CONDITIONS EXPECTED ON SUNDAY. SOME LOW- TO MID-LEVEL WIND ENHANCEMENT WILL OCCUR...BUT THIS WILL FALL WELL SHORT OF PRODUCING ANY WIND SHEAR ISSUES. TEMPERATURES OF GROUND AND DRY AIR REMAINING QUITE COLD OVERNIGHT WILL KEEP FOG CLEAN OUT OF THE PICTURE. OUTLOOK... SUN PM...VFR...NO SIG WX. MON AM...MAINLY VFR...CHC -FZDZ. MON AFTN-EVENING...MVFR/IFR RA LIKELY MON NGT-WED...VFR...NO SIG WX. && .HYDROLOGY... NO MAJOR PROBLEMS ARE EXPECTED ON THE MAIN STEM RIVERS THROUGH NEXT FRIDAY. ANY PRECIPITATION WHICH FALLS THROUGH THIS WEEKEND WILL BE SNOW. MONDAY MAY BRING SOME LIGHT MIXED PRECIPITATION EARLY AND 0.25" TO 0.50" OF RAIN DURING THE AFTERNOON. ICE FORMATION ON BODIES OF WATER IS EXPECTED TO INCREASE AGAIN THROUGH THE WEEKEND AS COLD AIR WILL BE IN PLACE ACROSS THE REGION. TEMPS WILL BEGIN RISING LATE SUNDAY AND MONDAY...ONLY COOLING TO NEAR OR SLIGHTLY ABOVE NORMAL NEXT WEEK. FOR DETAILS ON SPECIFIC AREA RIVERS AND LAKES...INCLUDING OBSERVED AND FORECAST RIVER STAGES AND LAKE ELEVATIONS...PLEASE VISIT THE ADVANCED HYDROLOGIC PREDICTION SERVICE /AHPS/ GRAPHS ON OUR WEBSITE. && .ALY WATCHES/WARNINGS/ADVISORIES... CT...WINTER WEATHER ADVISORY UNTIL 3 PM EST THIS AFTERNOON FOR CTZ001-013. NY...WINTER WEATHER ADVISORY UNTIL 3 PM EST THIS AFTERNOON FOR NYZ063>066. MA...NONE. VT...NONE. && $$ SYNOPSIS...SNYDER/SND NEAR TERM...SND SHORT TERM...BGM LONG TERM...BGM AVIATION...ELH HYDROLOGY...BGM
AREA FORECAST DISCUSSION
NWS ALBANY NY
1213 PM EST SAT JAN 21 2012 .SYNOPSIS... WEAK LOW PRESSURE WILL TRACK OFF THE NEW JERSEY COAST TODAY AND BRING SNOW TO THE AREA. A HIGH PRESSURE SYSTEM WILL BUILD INTO THE NORTHEAST TONIGHT AND SUNDAY BRINGING FAIR WEATHER. ON MONDAY...A POWERFUL STORM MOVES FROM THE UPPER GREAT LAKES INTO WESTERN QUEBEC...LIKELY BRINGING MIXED PRECIPITATION CHANGING TO RAIN. && .NEAR TERM /THROUGH TONIGHT/... SNOW WINDING DOWN ACROSS MOST OF THE FORECAST AREA. BEST LIFT WITH WARM ADVECTION AND SEEDER FEEDER PROCESS OVER SOUTHEAST. THIS WILL GRADUALLY MOVE EAST NEXT FEW HOURS. SOME CLEARING NOTED OVER FINGER LAKES/SOUTHERN ONTARIO AND THIS IS GRADUALLY MOVING IN. LOW CLOUDS HANGING TOUGH OVER MOST OF FORECAST AREA. CLOUD TOP TEMPS COLD ENOUGH FOR SNOW. WEAK WARM ADVECTION WILL CAUSE SOME LIGHT SNOW INTO AFTERNOON BUT LITTLE ACCUMULATION EXPECTED OUTSIDE FAR SOUTHEAST PART OF FORECAST AREA. TEMPS STILL NOT BUDGING MUCH. CURRENT FORECAST MAX AT ALBANY 24F TODAY BUT THIS MAY BE OPTIMISTIC IF CLOUDS DONT BREAK UP TILL LATE IN DAY. LATEST UPDATE TO MODIFY CLOUDS/POPS/WX/WINDS BASED ON OBS/RADAR AND 12Z NAM. PREVIOUS... WEAK MIDLEVEL SYSTEM MOVING FROM WEST TO EAST. SNOW HAS ENDED OR GREATLY DIMINISHED OVER NORTHWEST PART OF AREA. LATEST RUC ANALYSIS SHOWS H850 WARM ADVECTION CONTINUING ACROSS THE AREA AND VAD WIND PROFILE CONFIRMS THIS. SNOW SEEMS TO BE ENDING ONCE MID/HIGH LEVEL CLOUDS MOVE AWAY AND SEEDER FEEDER MECHANISM DIMINISHES. CLOUD TOPS COOLING OVER SOUTHEAST PART OF FORECAST AREA INDICATING ONE MORE BAND OF MODERATE SNOW POSSIBLE THERE LATE THIS MORNING BEFORE HIGHER CLOUDS MOVE OFF AND SNOW DIMINISHES. RECENT UPDATE TO ADJUST POPS WHERE SNOW HAS DIMINISHED OR ENDED. ALSO ADJUSTED MAX TEMPS DOWNWARD 2 DEGREES VALLEYS AND 3-5 DEGREES MOUNTAINS AS OBS SHOW TEMPS NOT MOVING THIS MORNING. && .SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/... WE BEGIN THIS SHORT TERM PORTION OF THE FORECAST ON A TRANQUIL NOTE WITH A 1035MB SURFACE HIGH SLIDING ACROSS THE EASTERN GREAT LAKES REGIONS AND NEW ENGLAND THROUGH THE DAY. FAIRLY DRY BELOW 500MB TO KEEP POPS AT ZERO AND SKIES PT-MOSUNNY. TEMPERATURES WILL BE SEASONABLE FOR THIS TIME OF THE YEAR WITH MAINLY 20S FOR THE TERRAIN AND LOWER 30S FOR THE VALLEY FLOOR. MEANWHILE...A POWERFUL SHORT WAVE COINCIDING WITH 150KT UPPER LEVEL JET WAS COMING ASHORE ACROSS CALIFORNIA. THIS SYSTEM IS FORECAST BY THE NCEP MODEL SUITE TO IMPACT THE 4-CORNERS REGION AND EJECT OUT ONTO THE CENTRAL-SOUTHERN PLAINS SUNDAY INTO MONDAY. A POWERFUL SURFACE CYCLONE WILL DEVELOP OVER THE MID-LOWER MISSISSIPPI RIVER VALLEY AND TRACK INTO THE CENTRAL GREAT LAKES REGION THROUGH MONDAY. THE MAIN IMPACT FOR OUR REGION WILL BE AN INCREASE IN CLOUD COVER AND A STRENGTHEN SOUTHERLY WIND. HOWEVER...ISSUES ARISE OVERNIGHT SUNDAY INTO MONDAY MORNING FOR THE REGION. A CLOSER EXAMINATION OF BUFKIT AND HOURLY BUFR PROFILES FROM THE MODEL SUITES THIS MORNING ALL SUGGEST A RAPID INCREASE IN LOWER LEVEL MOISTURE FROM SOUTH TO NORTH. COMBINE THAT WITH THE WIND MAGNITUDE INCREASE AND LOW LEVEL SHEAR FOR DRIZZLE FORMATION SINCE ICE NUCLEI IS NOT EXPECTED IN THE COLUMN WITH THE HEIGHT OF THE MOISTURE PROFILES STAYING BELOW THE -10C THROUGH AT LEAST 15Z MONDAY. DUE TO SEASONABLE TEMPERATURES EXPECTED ON SUNDAY...AND SOME PARTIAL CLEAR SKIES SUNDAY EVENING...OVERNIGHT SURFACE TEMPERATURES ARE EXPECTED TO DROP BACK INTO THE TEENS ACROSS THE DACKS AND LOW-MID 20S ELSEWHERE. THIS SEEMS TO SUGGEST THAT ANY DRIZZLE FORMATION WILL FREEZE ON CONTACT. TEMPERATURES ARE EXPECTED TO CLIMB ABOVE FREEZING ALONG THE HEELS OF THE STRENGTHEN SOUTHERLY FLOW BY NOON MONDAY WHERE WE WILL REMOVE THE MENTION OF FROZEN DRIZZLE/RAIN. MONDAY AFTERNOON...AN INCREASE IN LOW LEVEL WARM ADVECTION ALONG WITH THE APPROACH OF THE FRONTAL BOUNDARY WILL KEEP POPS QUITE HIGH FOR PERIODS OF RAIN/SHOWERS. THERE ARE SOME SUBTLE HINTS THAT THUNDER COULD BE A POSSIBILITY SOUTH OF THE CAPITAL REGION WITH SHOWALTER INDICES DROPPING BACK TO NEAR 1C AND SLIGHTLY FAVORABLE MID LEVEL LAPSE RATES. WE WILL CONTINUE TO MONITOR AND NOT MENTION IN THE FORECAST/GRIDS. HIGH TEMPERATURES COULD EXCEED 40F FOR THE MAJORITY OF THE REGION. THE FRONT AND ASSOCIATED MOISTURE TRACK QUICKLY TO OUR NORTHEAST WITH A DECREASE IN POPS. HOWEVER...WITH A NEAR VERTICALLY STACKED LOW OVER THE GREAT LAKES REGION AND COLD ADVECTION...LAKE ONTARIO CONTRIBUTION IS EXPECTED TO INCREASE. DELTA T/S ARE ONLY EXPECTED TO REMAIN MARGINAL SO WE WILL KEEP POPS FOR PORTIONS OF THE DACKS IN THE 30% THRESHOLDS FOR SNOW SHOWERS. && .LONG TERM /TUESDAY THROUGH FRIDAY/... THE AFOREMENTIONED LAKE EFFECT ACTIVITY COULD STILL BE IMPACTING PORTIONS OF THE DACKS WITH A WEST-SOUTHWEST BOUNDARY LAYER WINDS AROUND THE PERIPHERY OF THE SLOWLY DEPARTING UPPER LOW. OTHERWISE...BUILDING SURFACE PRESSURES ARE EXPECTED TUESDAY THROUGH WEDNESDAY. A WEAK MID LEVEL IMPULSE APPROACHES LATE WEDNESDAY AS THE MAIN IMPACT SHOULD BE FROM AN INCREASE IN HIGH- MID LEVEL MOISTURE. THURSDAY THRU FRIDAY...CONSIDERABLE UNCERTAINTY REMAINS AS THE GFS REMAINS THE MOST PROGRESSIVE AND THE ECMWF A BIT MORE PRONOUNCED WITH RESPECT TO APPALACHIANS STORM SYSTEM THAT COULD IMPACT THE REGION THURSDAY NIGHT INTO FRIDAY. ENSEMBLES FROM THE GFS OFFER A WIDE VARIETY OF SOLUTIONS WITH A FEW CLUSTERS EVEN STRONGER THAN THE ECMWF AND FURTHER WEST. FOR NOW...A LOW CONFIDENCE FORECAST FOR THE END OF THIS WEEK. && .AVIATION /12Z SATURDAY THROUGH WEDNESDAY/... MVFR CIGS/VSBY IN -SN EXIST OVER MOST OF FCA. OVER NEXT FEW HRS MOST AREAS FM ADIRONDACKS SOUTH WILL LOWER TO MVFR/IFR CIGS AND VSBY IN -SN. IFR CONDS WILL BE MORE WIDESPREAD SOUTH. CONDS WILL IMPV DURING THE AFTN BCMG MVFR FM NW TO SE...AND VFR BY EVENING. WINDS WILL BE NORTH-NORTHEAST AROUND 5-10 KT TODAY. OUTLOOK... SAT NIGHT-SUN...VFR. NO SIG WX. SUN NIGHT-MON MRNG...BCMG MVFR/IFR LATE. CHC -RA/-SN/-PL/-FZRA. MON AFTN...MVFR/IFR. RA LIKELY. MON NIGHT-TUE...VFR. SLIGHT CHC -SHRASN AND MVFR. TUE NIGHT-WED...VFR. NO SIG WX. && .HYDROLOGY... NO MAJOR PROBLEMS ARE EXPECTED ON THE MAIN STEM RIVERS THROUGH NEXT FRIDAY. ANY PRECIPITATION WHICH FALLS THROUGH THIS WEEKEND WILL BE SNOW. MONDAY MAY BRING SOME LIGHT MIXED PRECIPITATION EARLY AND 0.25" TO 0.50" OF RAIN DURING THE AFTERNOON. ICE FORMATION ON BODIES OF WATER IS EXPECTED TO INCREASE AGAIN THROUGH THE WEEKEND AS COLD AIR WILL BE IN PLACE ACROSS THE REGION. TEMPS WILL BEGIN RISING LATE SUNDAY AND MONDAY...ONLY COOLING TO NEAR OR SLIGHTLY ABOVE NORMAL NEXT WEEK. FOR DETAILS ON SPECIFIC AREA RIVERS AND LAKES...INCLUDING OBSERVED AND FORECAST RIVER STAGES AND LAKE ELEVATIONS...PLEASE VISIT THE ADVANCED HYDROLOGIC PREDICTION SERVICE /AHPS/ GRAPHS ON OUR WEBSITE. && .ALY WATCHES/WARNINGS/ADVISORIES... CT...WINTER WEATHER ADVISORY UNTIL 3 PM EST THIS AFTERNOON FOR CTZ001-013. NY...WINTER WEATHER ADVISORY UNTIL 3 PM EST THIS AFTERNOON FOR NYZ063>066. MA...NONE. VT...NONE. && $$ SYNOPSIS...SNYDER/SND NEAR TERM...SND SHORT TERM...BGM LONG TERM...BGM AVIATION...SNYDER HYDROLOGY...BGM
AREA FORECAST DISCUSSION
NWS COLUMBIA SC
226 PM EST SAT JAN 21 2012 .SYNOPSIS... A MOIST SOUTH FLOW WILL OCCUR AHEAD OF AN APPROACHING COLD FRONT. THE FRONT WILL MOVE THROUGH THE FORECAST AREA TODAY AND BE STALLED JUST SOUTH OF THE AREA SUNDAY. ANOTHER COLD FRONT WILL MOVE THROUGH THE AREA MONDAY. DRYING BEHIND THIS FRONT WILL DOMINATE TUESDAY. && .NEAR TERM /THROUGH TONIGHT/... THROUGH 800 PM...WIDESPREAD SHOWERS WERE OCCURRING AHEAD OF THE COLD FRONT. THE SOUTH LOW-LEVEL FLOW PLUS A MOISTURE AND INSTABILITY INCREASE ASSOCIATED WITH THE MID-LEVEL SHORTWAVE TROUGH WILL SUPPORT A FEW THUNDERSTORMS. THE EARLY AFTERNOON 88D VAD WIND PROFILE INDICATED WINDS OF 45 KNOTS AT 3000 FEET. THE LATEST RUC SHOWS THE SHEAR CONTINUING THROUGH THE REST OF THE AFTERNOON. ENOUGH INSTABILITY MAY DEVELOP FOR SEVERE THUNDERSTORMS. THE EARLY AFTERNOON ANALYSIS SHOWED LI/S RANGING FROM 4 IN THE NORTH TO AROUND ZERO IN THE SOUTH APART OF THE FORECAST AREA. UPSTREAM INSTABILITY SUPPORT THE NAM/S FORECAST OF LI/S LOWERING TO AROUND -2 OVER THE SOUTH PART. SEVERE THUNDERSTORMS APPEARS POSSIBLE IN THE SOUTH PART BASED ON THIS INSTABILITY AND SHEAR. AFTER 800 PM... THE COLD FRONT WILL SINK SOUTH OF THE FORECAST AREA TONIGHT. THE GFS AND NAM SHOW THE H85 JET LIFTING NORTHEAST OF THE FORECAST AREA EARLY WITH MOISTURE BECOMING SHALLOW BEHIND THE MID-LEVEL SHORTWAVE TROUGH. THE GFS AND NAM MOS INDICATE LOW POPS. FORECASTED CHANCE POPS MAINLY ASSOCIATED WITH LINGERING CONVERGENCE NEAR THE FRONT. USED THE GUIDANCE CONSENSUS FOR THE TEMPERATURE FORECAST. && .SHORT TERM /SUNDAY THROUGH SUNDAY NIGHT/... THE NAM AND GFS KEEP THE FRONT SOUTH OF THE AREA SUNDAY. THE MODELS KEEP MOISTURE SHALLOW BUT SHOULD ISENTROPIC LIFT DEVELOPING. THIS LIFT MAY SUPPORT LIGHT RAIN OR DRIZZLE. THE TEMPERATURE GUIDANCE APPEARS TOO WARM BECAUSE OF THE WEDGE PATTERN. EXPECT THE WEDGE PATTERN WILL REMAIN IN PLACE FOR MUCH OF SUNDAY NIGHT. THE MODELS SHOW ANOTHER COLD FRONT MONDAY WITH INCREASED MOISTURE AND CONVERGENCE. THE DEEPER MOISTURE APPEARS TO OCCUR DURING THE MORNING. THE WARMER TEMPERATURE GUIDANCE APPEARED BETTER SUNDAY NIGHT BECAUSE OF CLOUDINESS AND MIXING ASSOCIATED WITH THE APPROACHING FRONT. THE TEMPERATURE GUIDANCE WAS CLOSE MONDAY. && .LONG TERM /MONDAY THROUGH FRIDAY/... DRY RIDGING BEHIND THE COLD FRONT SHOULD DOMINATE TUESDAY. THE GFS AND ECMWF SUPPORT THIS DRY PATTERN. THE GFS AND ECMWF HAVE BEEN INCONSISTENT WITH THE TIMING AND MOISTURE DURING THE REST OF THE EXTENDED PERIOD. THE ECMWF HAS BEEN GENERALLY FASTER MOVING A WARM ADVECTION AND HIGH MOISTURE BACK INTO THE FORECAST AREA. THE GFS ENSEMBLE MEANS SUPPORT POPS LESS THAN 20 PERCENT WEDNESDAY...AND CHANCE POPS DURING THE REST OF THE EXTENDED PERIOD. && .AVIATION /20Z SATURDAY THROUGH THURSDAY/... WIDESPREAD SHOWERS WILL CONTINUE AHEAD OF THE COLD FRONT. THERE WILL ALSO BE A FEW THUNDERSTORMS...BUT THESE WERE NOT INCLUDED IN THE FORECAST EXPLICITLY BECAUSE OF TIMING UNCERTAINTY. STRONG WINDS ALOFT MAY MIX DOWN TO THE SURFACE WITH SOME OF THE STRONGER SHOWERS. GENERALLY EXPECT MVFR CONDITIONS IN THE WARM SECTOR AHEAD OF THE FRONT WITH LOWER CONDITIONS AT TIMES IN HEAVIER SHOWERS. THE COLD FRONT WILL SINK SOUTH OF THE AREA IN THE 04Z TO 08Z TIME FRAME. IFR CEILINGS WILL OCCUR IN THE MOIST NORTH FLOW BEHIND THE FRONT. EXTENDED AVIATION OUTLOOK...WIDESPREAD IFR CEILINGS WILL LIKELY OCCUR DURING THE REST OF SUNDAY AND SUNDAY NIGHT ASSOCIATED WITH A WARM FRONT. A COLD FRONT BE BE IN THE AREA MONDAY WITH CONTINUED RESTRICTIONS FOR MUCH OF MONDAY. WIDESPREAD IFR CONDITION MAY OCCUR WEDNESDAY NIGHT THROUGH THURSDAY ASSOCIATED WITH ANOTHER FRONTAL SYSTEM. && .CAE WATCHES/WARNINGS/ADVISORIES... SC...NONE. GA...NONE. && $$
AREA FORECAST DISCUSSION
NWS COLUMBIA SC
105 PM EST SAT JAN 21 2012 .SYNOPSIS... A MOIST SOUTH FLOW WILL OCCUR AHEAD OF AN APPROACHING COLD FRONT. THE FRONT WILL MOVE THROUGH THE FORECAST AREA TODAY AND BE STALLED JUST SOUTH OF THE AREA SUNDAY. ANOTHER COLD FRONT WILL MOVE THROUGH THE AREA MONDAY. DRYING BEHIND THIS FRONT WILL DOMINATE TUESDAY. && .NEAR TERM /THROUGH TONIGHT/... THROUGH 800 PM...WIDESPREAD SHOWERS WERE OCCURRING AHEAD OF THE COLD FRONT. THE SOUTH LOW-LEVEL FLOW PLUS A MOISTURE AND INSTABILITY INCREASE ASSOCIATED WITH THE MID-LEVEL SHORTWAVE TROUGH WILL SUPPORT THUNDERSTORMS. THE EARLY AFTERNOON 88D VD WIND PROFILE INDICATED WINDS OF 45 KNOTS AT 3000 FEET. THE LATEST RUC SHOWS THE SHEAR CONTINUING THROUGH THE REST OF THE AFTERNOON. ENOUGH INSTABILITY MAY DEVELOP FOR SEVERE THUNDERSTORMS. THE EARLY AFTERNOON ANALYSIS SHOWED LI/S RANGING FROM 4 IN THE NORTH TO AROUND ZERO IN THE SOUTH APART OF THE FORECAST AREA. UPSTREAM INSTABILITY SUPPORT THE NAM/S FORECAST OF LI/S LOWERING TO AROUND -2 OVER MUCH OF THE AREA DURING THE AFTERNOON. THE THREAT OF SEVERE WEATHER APPEARS TO BE UNTIL AROUND 800 PM BASED ON THE LATEST RUC MOISTURE CONVERGENCE PATTERN AND H85 JET. AFTER 800 PM... THE COLD FRONT WILL SINK SOUTH OF THE FORECAST AREA TONIGHT. THE GFS AND NAM SHOW THE H85 JET LIFTING NORTHEAST OF THE FORECAST AREA EARLY WITH MOISTURE BECOMING SHALLOW BEHIND THE MID-LEVEL SHORTWAVE TROUGH. THE GFS AND NAM MOS INDICATE LOW POPS. FORECASTED CHANCE POPS MAINLY ASSOCIATED WITH LINGERING CONVERGENCE NEAR THE FRONT. USED THE GUIDANCE CONSENSUS FOR THE TEMPERATURE FORECAST. && .SHORT TERM /SUNDAY THROUGH MONDAY/... THE NAM AND GFS KEEP THE FRONT SOUTH OF THE AREA SUNDAY. THE MODELS KEEP MOISTURE SHALLOW BUT SHOULD ISENTROPIC LIFT DEVELOPING. THIS LIFT MAY SUPPORT LIGHT RAIN OR DRIZZLE. THE TEMPERATURE GUIDANCE APPEARS TOO WARM BECAUSE OF THE WEDGE PATTERN. EXPECT THE WEDGE PATTERN WILL REMAIN IN PLACE FOR MUCH OF SUNDAY NIGHT. THE MODELS SHOW ANOTHER COLD FRONT MONDAY WITH INCREASED MOISTURE AND CONVERGENCE. THE DEEPER MOISTURE APPEARS TO OCCUR DURING THE MORNING. THE WARMER TEMPERATURE GUIDANCE APPEARED BETTER SUNDAY NIGHT BECAUSE OF CLOUDINESS AND MIXING ASSOCIATED WITH THE APPROACHING FRONT. THE TEMPERATURE GUIDANCE WAS CLOSE MONDAY. && .LONG TERM /MONDAY NIGHT THROUGH FRIDAY/... DRY RIDGING BEHIND THE COLD FRONT SHOULD DOMINATE TUESDAY. THE GFS AND ECMWF SUPPORT THIS DRY PATTERN. THE GFS AND ECMWF HAVE BEEN INCONSISTENT WITH THE TIMING AND MOISTURE DURING THE REST OF THE EXTENDED PERIOD. THE ECMWF HAS BEEN GENERALLY FASTER MOVING A WARM ADVECTION AND HIGH MOISTURE BACK INTO THE FORECAST AREA. THE GFS ENSEMBLE MEANS SUPPORT POPS LESS THAN 20 PERCENT WEDNESDAY...AND CHANCE POPS DURING THE REST OF THE EXTENDED PERIOD. && .AVIATION /18Z SATURDAY THROUGH THURSDAY/... WIDESPREAD SHOWERS WILL CONTINUE AHEAD OF THE COLD FRONT. THERE WILL ALSO BE A FEW THUNDERSTORMS...BUT THESE WERE NOT INCLUDED IN THE FORECAST EXPLICITLY BECAUSE OF TIMING UNCERTAINTY. STRONG WINDS ALOFT MAY MIX DOWN TO THE SURFACE WITH SOME OF THE STRONGER SHOWERS. GENERALLY EXPECT MVFR CONDITIONS IN THE WARM SECTOR AHEAD OF THE FRONT WITH LOWER CONDITIONS AT TIMES IN HEAVIER SHOWERS. THE COLD FRONT WILL SINK SOUTH OF THE AREA IN THE 04Z TO 08Z TIME FRAME. IFR CEILINGS WILL OCCUR IN THE MOIST NORTH FLOW BEHIND THE FRONT. EXTENDED AVIATION OUTLOOK...WIDESPREAD IFR CEILINGS WILL LIKELY OCCUR DURING THE REST OF SUNDAY AND SUNDAY NIGHT ASSOCIATED WITH A WARM FRONT. A COLD FRONT BE BE IN THE AREA MONDAY WITH CONTINUED RESTRICTIONS FOR MUCH OF MONDAY. WIDESPREAD IFR CONDITION MAY OCCUR WEDNESDAY NIGHT THROUGH THURSDAY ASSOCIATED WITH ANOTHER FRONTAL SYSTEM. && .CAE WATCHES/WARNINGS/ADVISORIES... SC...NONE. GA...NONE. && $$
AREA FORECAST DISCUSSION
NWS LINCOLN IL
1011 AM CST SAT JAN 21 2012 .DISCUSSION... ISSUED 1011 AM CST SAT JAN 21 2012 DESPITE RIDGE OF HIGH PRESSURE EXTENDING FROM THE NORTHERN GREAT LAKES INTO THE PLAINS...LOW CLOUDS CONTINUE TO BLANKET NEARLY ALL OF CENTRAL ILLINOIS THIS MORNING. THE EXCEPTION IS ACROSS THE FAR NORTHEAST KILX CWA AROUND KCMI AND KDNV...WHERE AN INTRUSION OF DRY AIR FROM THE NORTHEAST HAS RESULTED IN A LARGE BREAK IN THE OVERCAST. LOW-LEVEL PROFILERS ARE CURRENTLY SHOWING NORTHEASTERLY WINDS...HOWEVER THESE WILL VEER MORE EASTERLY THIS AFTERNOON AS THE HIGH PRESSURE CENTER SHIFTS INTO MICHIGAN. THIS SHOULD PUSH THE CLEARING SLOWLY WESTWARD AS THE DAY PROGRESSES...WITH MOSTLY SUNNY SKIES EXPECTED IN THE BLOOMINGTON-NORMAL AND SPRINGFIELD AREAS BY EARLY AFTERNOON. MEANWHILE...SKIES WILL REMAIN MOSTLY CLOUDY ALONG AND WEST OF THE ILLINOIS RIVER AND ALONG/SOUTH OF I-70. DUE TO A NORTHEASTERLY FETCH OFF LAKE MICHIGAN...THE NORTHWEST KILX CWA MAY EVEN SEE A FEW SNOW FLURRIES FROM TIME TO TIME. ZONE UPDATE HAS ALREADY BEEN ISSUED. BARNES && .AVIATION... ISSUED 556 AM CST SAT JAN 21 2012...FOR THE 12Z TAFS IFR STRATUS WILL CONTINUE THROUGH MID MORNING...WHEN THE CLOUD LAYER SHOULD LIFT TO MVFR. PIREPS ARE SHOWING THE CLOUD LAYER AS ABOUT 2K FT THICK...SO SOME CLEARING MAY DEVELOP AS MIXING DEEPENS INTO THE DRY LAYER ABOVE 3K FT. THE NORTHWEST EDGE OF THE STRATUS IS NOT PROGRESSING TO THE ESE AS YOU MIGHT EXPECT BEHIND A LOW PRESSURE SYSTEM. SO CLEARING IS A TOUGH CALL. RUC AND HRRR MODELS ARE SHOWING SOME DRYING WORKING INTO OUR AREA FROM THE NORTHEAST...AS SURFACE WINDS INCREASE FROM THE NORTHEAST. SO CMI AND DEC MAY BE THE EARLY TERMINAL SITES TO CLEAR OUT TO VFR THIS AFTERNOON. PIA/BMI/SPI MAY BE DELAYED BY A FEW HOURS TO 20-21Z. NOT HIGHLY CONFIDENT ON THE CLEARING SCENARIO...BUT WILL INCLUDE SOME VFR FROM LATE AFTERNOON THROUGH MID EVENING...WHEN MVFR CLOUDS RETURN ON SOUTHEAST WINDS. WILL KEEP WINDS IN THE 9-13KT RANGE FOR MOST OF THE NEXT 24 HOURS. SOUTHEAST WIND SPEEDS WILL INCREASE TONIGHT AS THE PRESSURE GRADIENT TIGHTENS AHEAD OF THE NEXT WEATHER SYSTEM. SHIMON && .PREV DISCUSSION... ISSUED 330 AM CST SAT JAN 21 2012 WILL ALLOW THE WINTER WEATHER ADVISORY EXPIRE BY 4 AM SE OF LINCOLN. MIXED PRECIPITATION HAS PASSED SE OF IL WITH 1008 MB LOW PRESSURE OVER EASTERN KY. FORECAST CONCERN IS IF ANY CLEARING OCCURS THIS AFTERNOON. THEN LOOKING AS A FAIRLY STRONG WX SYSTEM TO IMPACT THE REGION SUNDAY NIGHT WITH SPC HAVE SLIGHT RISK NEAR SOUTHERN PARTS OF RICHLAND AND LAWRENCE COUNTIES. NCEP FAVORED THE 00Z GFS MODEL WITH THIS WEATHER SYSTEM WITH ABOVE AVERAGE CONFIDENCE AND WILL FOLLOW SUITE. LEANED TOWARD THE 00Z ECMWF MODEL WITH MID/LATE WEEK SYSTEM NEXT WEEK WITH SPLIT UPPER LEVEL FLOW PREVAILING THEN. SHORT TERM...TODAY THROUGH TUESDAY NIGHT TRENDED CLOUDIER AND COOLER TODAY WITH FORECAST DUE TO EXTENSIVE LOW CLOUD COVER ACROSS IL...MO INTO SE HALF OF IA AND LOW LEVEL MOISTURE TRAPPED IN AN INVERSION. COULD BE A FEW PATCHES OF LIGHT FREEZING DRIZZLE INTO MID MORNING OVER CENTRAL IL THOUGH HAVE NOT SCENE ANY REPORTED NEARBY PAST FEW HOURS. TEMPS CURRENTLY RANGE FROM THE MID TEENS FROM PEORIA NW TO THE MID 20S SE OF I-70. NORTH WINDS 8 TO 16 MPH. 1027 MB HIGH PRESSURE OVER THE UPPER MS VALLEY NEAR THE WI/IA/MN BORDER TO DRIFT EAST ACROSS LOWER MI THIS AFTERNOON AND RIDGING INTO IL. THIS TO DECREASE LOW CLOUDS OVER NORTHERN AREAS WHERE SKIES BECOME PARTLY SUNNY...WHILE SE IL STAYS IN THE LOW CLOUDS TODAY. HIGHS MOSTLY IN THE 20S TODAY OVER CENTRAL IL AND LOWER 30S IN SE IL. SOUTHERLY FLOW TO SET UP TONIGHT AS HIGH PRESSURE STRENGTHENS TO 1033 MB AS IT MOVES INTO NEW ENGLAND AND MID ATLANTIC STATES BY DAWN SUNDAY. LOWS PROBABLY REACHED THIS EVENING THEN MAY SNEAK UP A FEW DEGREES OVERNIGHT AS LOW CLOUDS SPREAD BACK TO THE NORTH. A FAIRLY STRONG STORM SYSTEM MOVING EAST INTO THE ROCKIES WILL HAVE A DEEPENING STRONG LOW PRESSURE MOVING INTO THE UPPER MIDWEST SUNDAY NIGHT AND SWEEP A COLD FRONT EAST THROUGH IL SUNDAY EVENING. MILDER HIGHS IN THE 40S SUNDAY WITH LOWER 50S IN SE IL. HAVE SLIGHT CHANCE OF SHOWERS SUNDAY AFTERNOON...EXCEPT 30% CHANCE NW OF THE IL RIVER. LIKELY CHANCES OF SHOWERS SUNDAY NIGHT AND EVEN THUNDERSTORMS FROM I-55 EAST SUNDAY EVENING. WILL NEED TO WATCH SE IL WITH SLIGHT RISK INTO SOUTHERN PARTS OF RICHLAND AND LAWRENCE COUNTIES SUNDAY EVENING. VERY STRONG UPPER LEVEL DYNAMICS AND WIND FIELDS AND DEEP MOISTURE WITH STORM. TEMPS COULD RISE A BIT AHEAD OF THE COLD FRONT SUNDAY EVENING THEN FALL OVERNIGHT INTO MON MORNING. MODELS HAVE TRENDED FURTHER NE WITH LIGHT MIXED PRECIPITATION MONDAY WITH 1025 MB HIGH PRESSURE MOVING INTO THE TN VALLEY BY SUNSET MONDAY AND HAVE ADJUST FORECAST ACCORDINGLY. FAIR WEATHER EXPECTED MONDAY NIGHT THROUGH TUE NIGHT WITH NEARBY HIGH PRESSURE. LONG TERM...WEDNESDAY THROUGH FRIDAY NIGHT EXTENDED MODELS SHOW A SPLIT UPPER LEVEL FLOW DURING MID AND LATE WEEK OF NEXT WEEK AND HAVE TRENDED DRIER ON WED. STRONGER SOUTHERN STREAM SYSTEM WITH CUTOFF LOW OVER NORTHERN MEXICO INTO TX WED-THU KEEPS MOST OF ITS HEAVIER PRECIP SOUTH CENTRAL IL WHILE WEAKER NORTHERN STREAM SHORT WAVE MOVES EAST ACROSS THE NORTHERN TIER STATES. BEST CHANCE OF LIGHT PRECIPITATION APPEARS TO BE OVER SE IL WED NIGHT AND SHOULD BE WARM ENOUGH FOR RAIN THERE. BEST CHANCES OF PRECIPITATION APPEARS TO SHIFT EAST OF IL LATE NEXT WEEK AND TRENDED TOWARD A DRIER FORECAST. GFS AND ECMWF MODEL BOTH HAVE TRENDED DRIER DURING THIS TIME. TEMPS TO STAY ABOVE NORMAL DURING THIS TIME FRAME. HUETTL && .ILX WATCHES/WARNINGS/ADVISORIES... NONE. && $$
AREA FORECAST DISCUSSION
NWS INDIANAPOLIS IN
1131 AM EST SAT JAN 21 2012 .UPDATE... THE AVIATION SECTION HAS BEEN UPDATED BELOW. && .SYNOPSIS...LOW PRESSURE ACROSS EASTERN KENTUCKY AND TENNESSEE WILL MOVE ON TO THE EAST AS HIGH PRESSURE OVER WISCONSIN MOVES EAST ACROSS THE GREAT LAKES LATER TODAY. AN UPPER TROUGH OVER THE WEST COAST WILL MOVE INTO THE MID MISSISSIPPI VALLEY BY SUNDAY NIGHT AND ACROSS THE GREAT LAKES MONDAY AND MONDAY NIGHT. IN THE EXTENDED MODELS INDICATE A ZONAL FLOW OVER THE CENTRAL AND NORTHERN U.S. WHICH KEEPS THE ARCTIC AIR BOTTLED UP WELL TO THE NORTH AND CAUSES OUR TEMPERATURES TO BE QUITE MILD FOR THIS TIME OF THE YEAR. AN UPPER TROUGH IN THE SOUTHERN STREAM WILL BRING A CHANCE OF RAIN NEXT WEDNESDAY THROUGH FRIDAY. && .NEAR TERM /REST OF TODAY/... CURRENT SATELLITE DEPICTS CLEARING MOVING INTO THE NW COUNTIES A LITTLE QUICKER THAN EXPECTED. THE RUC 925-850 MB RELATIVE HUMIDITY FIELD APPEARS TO HAVE A GOOD HANDLE ON THIS WITH A GRADUAL CLEARING/DECREASE IN CLOUDS ACROSS THE ENTIRE CWA THROUGHOUT THE AFTERNOON. MODEL SOUNDINGS CONTINUE TO SHOW A DECENT LOW LEVEL INVERSION ACROSS THE SOUTHEASTERN CWA THROUGH AT LEAST 18Z THEN EXTENSIVE DRYING OF THE COLUMN THIS AFTERNOON. THEREFORE...CUT SKY GRIDS SIGNIFICANTLY ACROSS THE NORTHWEST FOR LATE THIS MORNING WITH THE TREND SHIFTING SOUTHEAST THROUGHOUT THE AFTERNOON. OTHER THAN THAT...CURRENT FORECAST IN GREAT SHAPE WITH ONLY MINOR TWEAKS TO HOURLY TEMPERATURES AND WINDS TO MATCH UP WITH CURRENT TRENDS. UPDATED GRIDS AND ZONES ALREADY SENT. && .SHORT TERM /TONIGHT THROUGH MONDAY NIGHT/... FORECAST FOCUS WILL BE ON SKY COVER NEXT FEW DAYS AND RAIN CHANCES TOWARDS THE END OF THE WEEKEND AS THE NEXT UPPER TROUGH APPROACHES. MODELS BEGIN INCREASING LOW LEVEL MOISTURE LATER TODAY AS LOW LEVEL FLOW BECOMES MORE SOUTHEAST AND THEN SOUTHERLY BY SUNDAY. THIS WILL CAUSE CLOUDS TO INCREASE AGAIN BY SUNDAY. SOME CLEARING COULD OCCUR ACROSS OUR NORTH FOR A WHILE TONIGHT AND IF IT DOES THE BOTTOM COULD DROP ON THE TEMPERATURES WITH SNOW COVER. OTHERWISE...WILL GO NEAR OR SLIGHTLY ABOVE MOS NUMBERS TONIGHT. MODELS INDICATE AN INCREASING SOUTHERLY FLOW ON SUNDAY AND THIS WILL OFTEN BREAK THE LOW LEVEL INVERSION. IF IT DOES TEMPERATURES MAY BECOME BE A LITTLE WARMER SUNDAY. HOWEVER WITH CLOUDS BEING THE RULE WILL GO WITH A MOS BLEND ON TEMPERATURES. WILL CONTINUE A 20 PERCENT CHANCE OF SHOWERS LATE SUNDAY AND THEN HIGH POPS ALL AREAS SUNDAY NIGHT AS COLD FRONT APPROACHES BY MONDAY MORNING. HOURLY TEMPERATURES MAY RISE SUNDAY NIGHT AND THEN FALL MONDAY AFTER COLD FRONT MOVES THROUGH. SPC HAS US IN A GENERAL RISK OF THUNDERSTORMS SUNDAY NIGHT AND EVEN A SLIGHT RISK UP TO OUR FAR SOUTHWEST. CAPES ARE VERY MARGINAL...BUT THERE IS A STRONG LOW LEVEL FLOW. WILL MENTION SCATTERED THUNDERSTORMS SOUTH AND ISOLATED THUNDERSTORMS ELSEWHERE SUNDAY NIGHT. PRECIPITATION GRADUALLY ENDING MONDAY AFTER COLD FRONT MOVES THROUGH. MODELS THICKNESS INDICATE A BRIEF PERIOD OF MIXED PRECIP COULD OCCUR NORTH AND CENTRAL SECTIONS MONDAY. FINALLY DRY WEATHER WILL BE THE RULE MONDAY NIGHT AS HIGH PRESSURE BUILDS IN FROM THE WEST. && .LONG TERM /TUESDAY THROUGH FRIDAY/... ENSEMBLES ARE SUGGESTING AN ACTIVE SPLIT FLOW TYPE PATTERN DEVELOPING IN THE EXTENDED. APPEARS THE MAIN ITEM OF INTEREST WILL BE WHAT HAPPENS TO A CUTOFF LOW THAT DEVELOPS OVER THE SOUTHWEST PARTS OF THE COUNTRY EARLY NEXT WEEK AND HOW IT MAY INTERACT WITH THE NORTHERN STREAM. THERE IS CONSIDERABLE SPREAD AMONG THE INDIVIDUAL MEMBERS AS TO WHEN OR EVEN IF THIS SYSTEM GETS PICKED UP BY THE NORTHERN STREAM. AT THIS POINT...ENSEMBLE DATA INDICATE AT LEAST SOME THREAT FOR PRECIPITATION FROM ABOUT WEDNESDAY ON. WILL GO WITH CHANCE POPS FOR THE WEDNESDAY THROUGH FRIDAY PERIODS. AT THIS TIME...THERE ARE STILL ONLY A COUPLE OF MEMBERS INDICATING POTENTIAL FOR SNOW...SO WILL CONTINUE TO KEEP MAJORITY OF PRECIPITATION TYPE AS RAIN. && .AVIATION /DISCUSSION FOR THE 211800Z TAFS/... MVFR THIS AFTERNOON...VFR THIS EVENING...THEN MVFR OVERNIGHT INTO SUNDAY. STUBBORN MVFR CLOUDS LOOK TO GRADUALLY ERODE FROM THE NORTHEAST DURING THE AFTERNOON HOURS. THERE IS STILL A CHANCE THAT THEY COULD GET TRAPPED BELOW AN INVERSION AND HANG ON INTO THE EVENING...BUT NOT CONFIDENT OF THAT SCENARIO. IT NOW APPEARS THAT LOW LEVEL MOISTURE WILL RETURN TO THE AREA OVERNIGHT AS WINDS BECOME SOUTHEAST. WINDS ALOFT WILL INCREASE FROM THE SOUTH ALSO BRINGING A RETURN OF MOISTURE. WILL BRING BACK MVFR CEILINGS BELOW BKN020 AFTER 08Z OR SO FROM SOUTH TO NORTH. WITH THE WARM AIR RETURNING OVER THE COLD GROUND CANNOT RULE OUT SOME FOG OR EVEN FREEZING DRIZZLE LATE TONIGHT INTO SUNDAY MORNING...BUT CONFIDENCE NOT HIGH ENOUGH TO PUT IN TAF YET. && .IND WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...JH NEAR TERM...HOMANN/MK SHORT TERM...JH LONG TERM...JS AVIATION...50
AREA FORECAST DISCUSSION
NWS INDIANAPOLIS IN
1107 AM EST SAT JAN 21 2012 .UPDATE... THE NEAR TERM SECTION HAS BEEN UPDATED BELOW. && .SYNOPSIS...LOW PRESSURE ACROSS EASTERN KENTUCKY AND TENNESSEE WILL MOVE ON TO THE EAST AS HIGH PRESSURE OVER WISCONSIN MOVES EAST ACROSS THE GREAT LAKES LATER TODAY. AN UPPER TROUGH OVER THE WEST COAST WILL MOVE INTO THE MID MISSISSIPPI VALLEY BY SUNDAY NIGHT AND ACROSS THE GREAT LAKES MONDAY AND MONDAY NIGHT. IN THE EXTENDED MODELS INDICATE A ZONAL FLOW OVER THE CENTRAL AND NORTHERN U.S. WHICH KEEPS THE ARCTIC AIR BOTTLED UP WELL TO THE NORTH AND CAUSES OUR TEMPERATURES TO BE QUITE MILD FOR THIS TIME OF THE YEAR. AN UPPER TROUGH IN THE SOUTHERN STREAM WILL BRING A CHANCE OF RAIN NEXT WEDNESDAY THROUGH FRIDAY. && .NEAR TERM /REST OF TODAY/... CURRENT SATELLITE DEPICTS CLEARING MOVING INTO THE NW COUNTIES A LITTLE QUICKER THAN EXPECTED. THE RUC 925-850 MB RELATIVE HUMIDITY FIELD APPEARS TO HAVE A GOOD HANDLE ON THIS WITH A GRADUAL CLEARING/DECREASE IN CLOUDS ACROSS THE ENTIRE CWA THROUGHOUT THE AFTERNOON. MODEL SOUNDINGS CONTINUE TO SHOW A DECENT LOW LEVEL INVERSION ACROSS THE SOUTHEASTERN CWA THROUGH AT LEAST 18Z THEN EXTENSIVE DRYING OF THE COLUMN THIS AFTERNOON. THEREFORE...CUT SKY GRIDS SIGNIFICANTLY ACROSS THE NORTHWEST FOR LATE THIS MORNING WITH THE TREND SHIFTING SOUTHEAST THROUGHOUT THE AFTERNOON. OTHER THAN THAT...CURRENT FORECAST IN GREAT SHAPE WITH ONLY MINOR TWEAKS TO HOURLY TEMPERATURES AND WINDS TO MATCH UP WITH CURRENT TRENDS. UPDATED GRIDS AND ZONES ALREADY SENT. && .SHORT TERM /TONIGHT THROUGH MONDAY NIGHT/... FORECAST FOCUS WILL BE ON SKY COVER NEXT FEW DAYS AND RAIN CHANCES TOWARDS THE END OF THE WEEKEND AS THE NEXT UPPER TROUGH APPROACHES. MODELS BEGIN INCREASING LOW LEVEL MOISTURE LATER TODAY AS LOW LEVEL FLOW BECOMES MORE SOUTHEAST AND THEN SOUTHERLY BY SUNDAY. THIS WILL CAUSE CLOUDS TO INCREASE AGAIN BY SUNDAY. SOME CLEARING COULD OCCUR ACROSS OUR NORTH FOR A WHILE TONIGHT AND IF IT DOES THE BOTTOM COULD DROP ON THE TEMPERATURES WITH SNOW COVER. OTHERWISE...WILL GO NEAR OR SLIGHTLY ABOVE MOS NUMBERS TONIGHT. MODELS INDICATE AN INCREASING SOUTHERLY FLOW ON SUNDAY AND THIS WILL OFTEN BREAK THE LOW LEVEL INVERSION. IF IT DOES TEMPERATURES MAY BECOME BE A LITTLE WARMER SUNDAY. HOWEVER WITH CLOUDS BEING THE RULE WILL GO WITH A MOS BLEND ON TEMPERATURES. WILL CONTINUE A 20 PERCENT CHANCE OF SHOWERS LATE SUNDAY AND THEN HIGH POPS ALL AREAS SUNDAY NIGHT AS COLD FRONT APPROACHES BY MONDAY MORNING. HOURLY TEMPERATURES MAY RISE SUNDAY NIGHT AND THEN FALL MONDAY AFTER COLD FRONT MOVES THROUGH. SPC HAS US IN A GENERAL RISK OF THUNDERSTORMS SUNDAY NIGHT AND EVEN A SLIGHT RISK UP TO OUR FAR SOUTHWEST. CAPES ARE VERY MARGINAL...BUT THERE IS A STRONG LOW LEVEL FLOW. WILL MENTION SCATTERED THUNDERSTORMS SOUTH AND ISOLATED THUNDERSTORMS ELSEWHERE SUNDAY NIGHT. PRECIPITATION GRADUALLY ENDING MONDAY AFTER COLD FRONT MOVES THROUGH. MODELS THICKNESS INDICATE A BRIEF PERIOD OF MIXED PRECIP COULD OCCUR NORTH AND CENTRAL SECTIONS MONDAY. FINALLY DRY WEATHER WILL BE THE RULE MONDAY NIGHT AS HIGH PRESSURE BUILDS IN FROM THE WEST. && .LONG TERM /TUESDAY THROUGH FRIDAY/... ENSEMBLES ARE SUGGESTING AN ACTIVE SPLIT FLOW TYPE PATTERN DEVELOPING IN THE EXTENDED. APPEARS THE MAIN ITEM OF INTEREST WILL BE WHAT HAPPENS TO A CUTOFF LOW THAT DEVELOPS OVER THE SOUTHWEST PARTS OF THE COUNTRY EARLY NEXT WEEK AND HOW IT MAY INTERACT WITH THE NORTHERN STREAM. THERE IS CONSIDERABLE SPREAD AMONG THE INDIVIDUAL MEMBERS AS TO WHEN OR EVEN IF THIS SYSTEM GETS PICKED UP BY THE NORTHERN STREAM. AT THIS POINT...ENSEMBLE DATA INDICATE AT LEAST SOME THREAT FOR PRECIPITATION FROM ABOUT WEDNESDAY ON. WILL GO WITH CHANCE POPS FOR THE WEDNESDAY THROUGH FRIDAY PERIODS. AT THIS TIME...THERE ARE STILL ONLY A COUPLE OF MEMBERS INDICATING POTENTIAL FOR SNOW...SO WILL CONTINUE TO KEEP MAJORITY OF PRECIPITATION TYPE AS RAIN. && .AVIATION /DISCUSSION FOR THE 211430Z TAF UPDATE/... UPDATE...AREA OF MVFR CEILINGS ACROSS OH HAS WORKED SOUTHWEST INTO CENTRAL INDIANA. THESE CLOUDS LOOK TO PERSIST FOR AT LEAST A FEW HOURS BEFORE BREAKING UP/MOVING OUT. THUS HAVE KEPT MVFR CEILINGS LONGER AT KIND. PREVIOUS DISCUSSION... BACK EDGE OF VFR CEILINGS AROUND 050 PROGRESSING SOUTH ACROSS NORTHERN INDIANA. MODEL DATA SUGGEST DRIER AIR WILL BE WORKING IN FROM THE NORTH TODAY...SO EXPECT THIS TREND TO CONTINUE...WITH CEILINGS SCATTERING OUT FROM NORTH TO SOUTH FROM LATE THIS MORNING INTO THE AFTERNOON HOURS. STILL SOME POCKETS OF MVFR CEILINGS AROUND 020...SO THESE LOWER CEILINGS WILL PROBABLY IMPACT THE TAF SITES FROM TIME TO TIME THROUGH LATE THIS MORNING. MAY SEE OCCASIONAL SURFACE WIND GUSTS 15-18KTS FROM 010-030 HEADINGS THROUGH MIDDAY AS PRESSURE RISE MAX MOVES THROUGH. && .IND WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...JH NEAR TERM...HOMANN/MK SHORT TERM...JH LONG TERM...JS AVIATION...JAS/50
AREA FORECAST DISCUSSION
NWS QUAD CITIES IA IL
1212 PM CST SAT JAN 21 2012 .AVIATION... CLOUD TRENDS BIGGEST CHALLENGE WITH 18Z TAFS. STRATUS WITH MVFR CIGS CONTINUES TO BLANKET THE REGION EARLY THIS AFTN. THE CLEARING THAT HAD WORKED INTO KDBQ FROM THE NORTH HAS SINCE STALLED AND RETREATED BACK NWD WITH ONSET OF LLVL WARM ADVECTION AND E/SE WINDS SFC-925 MB. SATL SHOWS WEDGE OF CLEARING INTO CENTRAL IL WITH REGION OF DRY AIR AT 925 MB. AS THE FLOW CONTINUES TO VEER TO E/SE THERE IS POTENTIAL FOR THIS DRIER AIR AND CLEARING TO OVERSPREAD THE TERMINALS... MAINLY KBRL AND POSSIBLY KMLI AND KDBQ... LATE AFTN THROUGH THIS EVE. LATEST HRRR MODEL CAPTURES CURRENT CLEARING TRENDS FAIRLY WELL AND DEPICTS CLEARING INTO PORTIONS OF EASTERN IA... AND SO HAVE INTRODUCED AT KBRL WHERE CONFIDENCE IS GREATEST AND TEMPO AT KMLI THIS EVE... BUT LEFT OUT AT KDBQ. WILL JUST HAVE TO WATCH CLOUD TRENDS AND AMEND AS TRENDS BECOME BETTER IDENTIFIED. ANY CLEARING LIKELY TO BE SOMEWHAT SHORTLIVED WITH LOW CLOUDS AND MAINLY MVFR CIGS REDEVELOPING OVRNGT INTO SUN AM WITH STRENGTHENING LOW LEVEL WARM...MOIST ADVECTION. THERE IS WINDOW OF LLWS POTENTIAL LATE EVE INTO EARLY OVRNGT AND HAVE ADDED MENTION IN TAFS... AS WINDS AROUND 2000 FT AGL INCREASE FROM S/SE TO 40-45 KTS WHILE SFC WINDS GENERALLY E/SE 10-15KTS WITH SOME GUSTS POSSIBLE. FEW FLURRIES EXPECTED BENEATH STRATUS WITH ANY LINGERING PCPN LIKELY TRANSITIONING TO FREEZING DRIZZLE AS TEMPS WARM JUST ABOVE AND LOSE ICE INTRODUCTION. LOW CONFIDENCE ON COVERAGE PRECLUDES MENTION ATTIM. && .PREV DISCUSSION... /ISSUED 330 AM CST SAT JAN 21 2012/ SYNOPSIS... LATEST SFC ANALYSIS WAS INDICATING HIGH PRESSURE COMPLEX OCCUPYING MUCH OF THE UPPER MS RVR VALLEY...DOWN INTO THE CENTRAL PLAINS WITH LARGE PRESSURE RISES NOTED TO THE LEE OF IT ACRS SOUTHEAST WI INTO EASTERN OK ATTM. LLVL STRATUS DECK ON ITS EASTERN AND SOUTHERN FLANK SHOWING LITTLE SIGNS OF WANTING TO BUDGE SOUTHWARD. ALOFT... WATER VAPOR IMAGERY AND 00Z UA ANALYSIS WERE INDICATING THAT WHILE L/W TROFFINESS WAS STARTING TO EXIT THE REGION TO THE EAST...BROAD UPPER RIDGING WAS SLIDING ACRS THE PLAINS. FURTHER UPSTREAM...W/V IMAGERY WAS INDICATING YET ANOTHER LARGE SLUG OF UPPER WAVE ENERGY PUMMELING ITS WAY INTO THE WEST COAST. SHORT TERM...TODAY AND TONIGHT... TODAY...BACKING ELEVATED FLOW TO WARM AIR ADVECT BIG TIME TODAY IN THE H8-H7 MB LAYER THROUGH THIS EVENING. THE SFC RIDGE CENTER MENTIONED ABOVE WILL LOOK TO MIGRATE TO EASTERN LOWER MI BY LATE AFTERNOON WITH SFC WINDS VEERING TO AN EAST TO SOUTHEASTERLY SFC COMPONENT AS THE DAY PROGRESSES. SFC WINDS OF 5 TO 8 MPH PRODUCING NEAR ADVISORY LEVEL WIND CHILLS IN THE EXTREME NORTHWEST PORTION OF THE DVN CWA ATTM IN AREA OF SOME CLEARING...BUT NOT WIDESPREAD ENOUGH OR TO LAST LONG ENOUGH TO WARRANT AN ADVISORY WITH THE LIGHTER WIND REGIME IN VCNTY OF IN-BUILDING RIDGE. FEEL THE SHORT RANGE MODELS NOT HANDLING THE LLVL STRATUS ALL THAT WELL AND THAT IT MAY REMAIN TRAPPED UNDER THE BUILDING INVERSION FOR MUCH OF THE DAY ESPECIALLY ACRS THE SOUTHERN HALF TO TWO THIRDS OF THE DVN CWA. WILL SLOW THE CLEARING AN MAY KEEP MUCH OF THE CWA MOSTLY CLOUDY INTO AT LEAST EARLY AFTERNOON. AREAS NORTH OF I80 SHOULD HAVE THE BEST CHANCE OF CLEARING THIS AFTERNOON WITH SOME DIURNAL MIXING IN THINNER CLOUD LAYER. WITH THE CLOUDS...WILL LEAN TOWARD THE COLDER SIDE OF GUIDANCE HIGHS AS THE WARMING MORE REALIZED ALOFT. SOME AREAS NOT RECOVERING MUCH WARMER THAN WHERE THEY ARE AT NOW. AREAS THAT HAVE THE BEST CHANCE OF CLEARING ALSO HAVE THE DEEPER SNOW COVER THUS COULD LIMIT THE HIGHS EVEN IN THOSE AREAS. TONIGHT...EVEN IF CLOUDS CLEAR OUT IN MUCH OF THE CWA FOR A PERIOD LATE THIS AFTERNOON AND INTO THE EVENING...EXPECT INCREASING RETURN FLOW/WAA REGIME TO SLOSH BACK LOW CLOUDS UNDER THE INVERSION OR SET UP A SITUATION WHERE THE LOW DECK WILL REFORM AS THE NIGHT PROGRESSES. FCST SOUNDINGS SHOW A POTENTIAL DRIZZLE SCENARIO IN AT LEAST THE SOUTH HALF OF THE DVN CWA AFTER 08Z SUNDAY AS BOUNDARY LAYER MOISTURE TRAPPED UNDER THE INVERSION IN A TEMP PROFILE OF 0 TO -5C INCREASES ENOUGH TO A DEPTH TO SUPPORT VERY LIGHT PRECIP AND THE DRY MILDER LAYER ALOFT REMAINS AT DEEP ENOUGH WEDGE TO PREVENT SEEDER FEEDERS. POS OMEGAS/LIFT THROUGH PART OF THE COLUMN ENOUGH TO INDUCE SOME LIGHT PRECIP TO ALSO COMMENCE LATE TONIGHT FROM THE WEST. ALTHOUGH EXPECT NIGHT TIME LOWS TO OCCUR DURING THE MID EVENING WITH STEADY TO SLOWLY RISING TEMPS AFTER THAT INTO SUNDAY MORNING...SFC TEMPS PROBABLY NOT TO RECOVER ABOVE FREEZING WHERE THE DRIZZLE BREAKS OUT SO WILL ADD PATCHY FREEZING DRIZZLE FOR NOW ALONG AND SOUTH OF THE I80 CORRIDOR. THINK MIXING SOUTHEAST SFC WINDS WILL BE STRONG ENOUGH AFTER MIDNIGHT OF 10-15+ KTS...AS WELL AS SFC DPTS NOT HIGH ENOUGH TO FOSTER WIDESPREAD DENSE FOG DEVELOPMENT AND WILL KEEP OUT MENTION FOR NOW. ..12.. LONG TERM...SUNDAY THROUGH FRIDAY... THE MODEL SOLUTIONS ARE COMING INTO BETTER AGREEMENT WITH THE LATE WEEKEND SYSTEM. A POTENT S/W JUST OFF THE NORTHERN CA COAST EARLY THIS MORNING WILL MOVE THROUGH THE WESTERN U.S. TODAY AND TONIGHT THEN SWING NORTHEAST REACHING THE WESTERN GREAT LAKES BY LATE MONDAY. THERE WILL BE A GOOD FEED OF GULF MOISTURE AHEAD OF THE SYSTEM...BUT MODEL SOLUTIONS SHOW THE BULK OF THE LOW LEVEL MOIST FEED BEING DEFLECTED TO OUR EAST AND NORTH. THE ECMWF WITH IT/S DEEPER AND SLOWER SOLUTION PULLS SOME OF THE MOISTURE/PRECIP BACK INTO THE EASTERN HALF OF THE CWFA. SUNDAY NIGHT AND MONDAY MORNING. FOR SUNDAY AND SUNDAY NIGHT SOUTHERLY LOW LEVEL FLOW OVER THE NEW SNOWPACK RAISES THE POTENTIAL FOR STRATUS/DRIZZLE...ESPECIALLY WITH THE MID LEVELS REMAIN DRY MOST OF THE SUNDAY. INTRODUCED SOME PATCHY DRIZZLE FOR THE LATE MORNING AND AFTERNOON HOURS OVER MUCH OF THE AREA. TEMPERATURES OVER THE NORTHERN THIRD OF THE FORECAST AREA...WHERE THE DEEPER SNOW IS...WILL LIKELY STAY BELOW FREEZING UNTIL SUNDAY AFTERNOON...SO MENTIONED PATCHY FREEZING DRIZZLE IN THE NORTH SUNDAY MORNING. CHANCE WEST TO LIKELY POPS EAST WERE MAINTAINED FOR SUNDAY NIGHT WITH THE UPPER TROF AXIS LIFTING THROUGH AND DEEPER MOISTURE MOVING IN. THIS SHOULD BE A RAIN CHANGING TO SNOW SCENARIO FOR SUNDAY NIGHT AS COLDER AIR MOVES IN. PTYPE BY LATE SUNDAY NIGHT SHOULD BE SNOW. DUE TO THE MIXED NATURE OF THE PRECIPITATION DURING THE FIRST PART OF THE EVENT...HAVE KEPT SNOWFALL AMOUNTS TO LESS THAN AN INCH...AND THAT SHOULD BE OVER THE NWRN CWFA. THERE IS ALSO A LOW THREAT OF SOME FREEZING RAIN DURING THE TRANSITION PERIOD SUNDAY EVENING ESPECIALLY IN EAST CENTRAL IOWA. AFTER MONDAY THE MID LEVEL FLOW BECOMES MORE ZONAL OVER THE NORTHERN U.S. ANOTHER TROF MOVES THROUGH THE REGION TUESDAY NIGHT AND WEDNESDAY. SO FAR THIS FEATURE APPEARS TO BE MOISTURE STARVED AND ONLY WARRANTS LOW CHANCE POPS FOR A RAIN/SNOW MIX. THE PREDOMINANT WEST TO EAST FLOW MID TO LATE WEEK SHOULD PREVENT ANY INTRUSION OF THE COLD AIR OVER CANADA...RESULTING IN NEAR TO ABOVE NORMAL TEMPERATURES. ..DLF.. && .DVN WATCHES/WARNINGS/ADVISORIES... IA...NONE. IL...NONE. MO...NONE. && $$
AREA FORECAST DISCUSSION
NWS DODGE CITY KS
500 PM CST SAT JAN 21 2012 .AVIATION... FOR THE 00Z TAF ISSUANCE...MAIN CONCERN IN THE AVIATION WORLD IS WINDS. FOLLOWED RECENT HRRR GUIDANCE WHICH KEEPS SOUTHERLY WINDS 15 TO 20 KT THROUGH THE OVERNIGHT. MEANWHILE, AN APPROACHING COLD FRONT IS EXPECTED TO TRAVERSE ACROSS THE REGION BY TOMORROW MORNING. SO WINDS WILL VEER TO THE SW THEN FINALLY TO THE NW AFTER THE FRONT PASSES THROUGH. ALL GUIDANCE SUPPORTS STRONG WINDS SO HAVE INCREASED WINDS IN THE 26-32KT RANGE WITH GUSTS TO 35-40KT BY AND AFTER 15Z TOMORROW. OTHERWISE, VFR CIGS WILL PREVAIL. -SUGDEN && .PREV DISCUSSION... /ISSUED 303 PM CST SAT JAN 21 2012/ DISCUSSION... DAYS 1-2... THE MAIN FORECAST FOCUS WILL ON THE CHANCE FOR PRECIP DURING THE PERIOD AND TEMPERATURES. WV IMAGERY AND 12Z UPPER AIR ANALYSIS INDICATE A WEAK UPPER LEVEL RIDGE OF HIGH PRESSURE TRANSITIONING EAST ACROSS THE CENTRAL PLAINS. MEANWHILE, AN UPPER LEVEL TROUGH OF LOW PRESSURE IS PUSHING ASHORE IN NORTHERN CALIFORNIA. NEAR THE SURFACE, A LEE SIDE TROUGH OF LOW PRESSURE PREVAILS ACROSS EASTERN COLORADO. SHORT RANGE MODELS INDICATE THE UPPER LEVEL TROUGH PUSHING EAST ACROSS THE FOUR CORNERS REGION TONIGHT AND INTO THE WESTERN HIGH PLAINS SUNDAY BRINGING THE POSSIBILITY FOR PRECIP TO PORTIONS OF WESTERN AND CENTRAL KANSAS BY SUNDAY AFTERNOON. A STRONG H5 VORT MAX IS PROGGED TO PASS THROUGH WESTERN KANSAS BY 18Z IN CONJUNCTION WITH A COLD FRONT ASSOCIATED WITH THE UPPER TROUGH AXIS. HOWEVER THE STRONG JET CORE ASSOCIATED WITH THE SYSTEM WILL REMAIN JUST OFF TO OUR SOUTH ACROSS WEST TEXAS. ADDITIONALLY, LOW LEVEL MOISTURE WILL BE LACKING WITH H85 DEWPOINTS PROJECTED TO REMAIN WELL BELOW 0C, NOT TO MENTION A LACK OF MID LEVEL INSTABILITY. STILL, THE NAM, GFS, AND ECMWF SHOW INCREASED MOISTURE ADVECTION IN THE MID LEVELS ALONG WITH A POST FRONTAL H7 BAROCLINIC ZONE PASSING ACROSS WESTERN KANSAS SUNDAY AFTERNOON. CANNOT RULE OUT A FEW PASSING SPRINKLES OR AN ISOLATED SHOWER OR TWO ACROSS WESTERN AND CENTRAL KANSAS. AT THE VERY LEAST INCREASED CLOUDINESS WITH VIRGA WILL BE POSSIBLE CONSIDERING THE DRIER LOW LEVELS. WILL LOWER POPS DOWN TO SLIGHT CATEGORY ACROSS SOUTH CENTRAL AND EXTREME SOUTHWEST KANSAS WHILE LEAVING LOW END CHANCE CATEGORY POPS IN NEAR THE I-70 CORRIDOR. TEMPERATURES WILL BE MUCH WARMER TONIGHT AS LEE SIDE TROUGHING STRENGTHENS OVERNIGHT. THIS WILL ENHANCE WARM AIR ADVECTION INTO WESTERN KANSAS WITHIN A LOW LEVEL SOUTHWESTERLY FLOW RAISING H85 TEMPERATURES UP TO AROUND 10C TO 12C. ADDITIONALLY, MOISTURE ADVECTION WILL INCREASE SURFACE DEWPOINTS UP INTO THE 20S(F) ACROSS SOUTH CENTRAL AND SOUTHWEST KANSAS. LOOK FOR LOWS MAINLY DOWN INTO THE 30S(F) WITH THE WARMER TEMPERATURES ACROSS OUR EXTREME SOUTHWEST WHERE DOWNSLOPING WILL BE MORE OF A FACTOR TOWARD 12Z. FOR SUNDAY, A COLD FRONT WILL QUICKLY PUSH EAST ACROSS WESTERN KANSAS BY LATE MORNING TURNING WINDS NORTHWESTERLY. EVEN SO, DOWNSLOPING COMBINED WITH THE INITIAL MIXING OF WARMER AIR JUST OFF THE DECK (H85 TEMPERATURES AROUND 10C) AS THE FRONT MOVES THROUGH, WILL ALLOW TEMPERATURES TO CLIMB WELL UP INTO THE 40S(F) WITH SOME LOWER TO MID 50S(F) POSSIBLE BY EARLY AFTERNOON. LOW TEMPERATURES ARE EXPECTED TO FALL BACK BELOW FREEZING SUNDAY NIGHT AS DECREASING WINDS AND CLOUDS ACCOMPANY A SMALL AREA OF SURFACE HIGH PRESSURE MOVING EAST ACROSS SOUTHWEST KANSAS. AS FOR MONDAY, LEE SIDE TROUGHING WILL QUICKLY DEVELOP ACROSS EASTERN COLORADO HELPING TO RETURN SOUTHERLY WINDS TO WESTERN KANSAS BY MONDAY AFTERNOON. THE NAM, GFS, AND ECMWF SHOW H85 TEMPERATURES RANGING FROM JUST ABOVE 0C ACROSS CENTRAL KANSAS TO NEAR 5C ALONG THE COLORADO BORDER. ALONG WITH PLENTY OF SUNSHINE, LOOK FOR HIGHS UP INTO THE 50S(F) MONDAY. WINDS WILL BE FAIRLY STRONG OUT OF THE NORTHWEST LATE SUNDAY MORNING AND AFTERNOON. ALL MODELS SHOW H85-H7 WINDS AROUND 40 TO 50KT JUST BEHIND THE FRONT. WITH SOME MIXING EXPECTED AS THE FRONT MOVES THROUGH, WIND ADVISORY WINDS ARE EXPECTED TO BE MET. HOWEVER, LESS CERTAINTY REMAINS AS TO WHERE A BRIEF HIGH WIND GUST MAY OCCUR TO WARRANT A HIGH WIND WARNING. WILL DEFER TO THE NEXT SHIFT WITH A HIGH WIND WATCH ALREADY ALERTING THE PUBLIC TO THE POTENTIAL OF STRONGER WINDS. DAYS 3-7... FOR TUESDAY AN UPPER LEVEL SHORTWAVE TROUGH WILL BE GOING THROUGH THE NORTHERN PLAINS WHILE AN UPPER CLOSED LOW CONTINUES TO DIG INTO SOUTHERN NEW MEXICO. KANSAS WILL BE IN BETWEEN THESE TWO SYSTEMS WITH ONLY SOME HIGH LEVEL CLOUDINESS EXPECTED. LOWS ON TUESDAY MORNING WILL RANGE FROM THE MID TO UPPER 20S. HIGHS WILL BE IN THE MID TO UPPER 40S, TO AROUND 50 SOUTHEAST FA AROUND MEDICINE LODGE. FOR WEDNESDAY ANOTHER NORTHERN BRANCH WAVE MOVES ACROSS THE PLAINS WITH WINDS SHIFTING NORTHERLY WHILE THE SOUTHERN UPPER LOW GETS CUTOFF IN NORTHERN MEXICO. NEAR THE WIND SHIFT IN THE SOUTHEAST AROUND MEDICINE LODGE THE DEWPOINTS RISE INTO THE MID 30S WITH A SLIGHT CHANCE FOR RAIN EARLY WEDNESDAY MORNING. NOT MUCH CHANGE IN THE TEMPERATURES FOR WEDNESDAY WITH MORNING LOWS IN THE UPPER 20S NORTH TO MID 3OS SOUTHEAST. HIGHS WILL BE AROUND 50. ON THURSDAY DRY NORTHWESTERLY FLOW CONTINUES WITH A LEE TROUGH DEVELOPING. LOWS WILL BE AROUND 30 WITH WARMER HIGHS IN THE MID 50S. FOR FRIDAY A STRONGER NORTHERN BRANCH SHORTWAVE TROUGH MOVE INTO THE NORTHERN AND CENTRAL PLAINS WITH COOLER HIGH PRESSURE MOVING INTO THE PLAINS. MORNING LOWS WILL BE IN THE LOW TO MID 30S WITH HIGH TEMPS A BIT COOLER AND AROUND 50. ON SATURDAY THE EC MODEL HAS A DEEPER TROUGH MOVING THROUGH THE UPPER MIDWEST IN THE MORNING, WHILE THE GFS IS FLATTER WITH A MORE ZONAL FLOW. LOWS LOOK TO BE IN THE MID 20S NORTH TO AROUND 30 SOUTH WITH COOLER HIGHS IN THE MID 40S. && .PRELIMINARY POINT TEMPS/POPS... DDC 30 50 22 53 / 0 30 0 0 GCK 32 50 20 52 / 0 30 0 0 EHA 37 52 23 53 / 0 20 0 0 LBL 35 53 20 55 / 0 20 0 0 HYS 28 48 20 50 / 0 30 0 0 P28 28 55 25 55 / 0 20 0 0 && .DDC WATCHES/WARNINGS/ADVISORIES... WIND ADVISORY FROM 10 AM CST /9 AM MST/ TO 4 PM CST /3 PM MST/ SUNDAY FOR KSZ030-031-045-046-061-064>066-074-078>081-084- 088>090. WIND ADVISORY UNTIL 6 PM CST /5 PM MST/ THIS EVENING FOR KSZ043- 044-061>063-074>077-084>087. HIGH WIND WATCH FROM SUNDAY MORNING THROUGH SUNDAY AFTERNOON FOR KSZ043-044-062-063-075>077-085>087. && $$ FN99/99/36
AREA FORECAST DISCUSSION
NWS GOODLAND KS
1039 AM MST SAT JAN 21 2012 .DISCUSSION... 420 AM MST SAT JAN 21 2012 MAIN FORECAST PROBLEM WILL BE THE WINDS THROUGH SUNDAY BUT MANY OTHER CONCERNS ARE JUST BELOW THE WINDS. SATELLITE SHOWING AN ACTIVE/PROGRESSIVE WAVE TRAIN FROM THE PACIFIC INTO THE WESTERN ATLANTIC. BROAD UPPER TROUGH REMAINS IN PLACE OVER THE PACIFIC WITH A STRONG SHORTWAVE TROUGH APPROACHING THE WEST COAST. ALSO BIG LOW LEVEL TEMPERATURE GRADIENT SLIDING BACK AND FORTH ACROSS THE AREA. AT JET LEVEL...EXTREMELY STRONG JET OVER THE EASTERN PACIFIC BEHIND INCOMING TROUGH. BASED ON WHAT OBSERVATIONS ARE OUT THERE...THE MODELS ARE UNDERDOING THE STRENGTH OF THE NEAR 200 KNOT JET. BASED ON AVAILABLE DATA...THE GFS AND NAM LOOK TO HAVE THE BEST STRENGTH BUT THE NAM/CANADIAN HAVE BEST ORIENTATION. OVER THE COUNTRY...THE NAM AND CANADIAN HAVE THE BEST HANDLE ON THE JET THAT STARTED NEAR OUR AREA LAST NIGHT. THE OTHER MODELS TENDED TO BE TOO FAR EAST. SATELLITE AND UPPER AIR WOULD SUPPORT THE ECMWF/CANADIAN BEING THE BEST AT MID LEVELS. MODELS TENDED TO BE TOO MOIST AT MID LEVELS WITH THE CANADIAN AND UKMET DOING THE BEST. MODELS CONTINUING TO HAVE TROUBLE WITH THE LOW LEVEL THERMAL FIELD. OVERALL THE UKMET AND CANADIAN WAS DOING A LITTLE BETTER THAN THE GFS...ESPECIALLY WITH THE POSITION OF THE COLD POOL TO OUR NORTH AND EAST. TODAY/TONIGHT...NEWER GUIDANCE HAS COME IN A LITTLE STRONGER WITH THE WINDS. MODELS SHOW LITTLE TO NO MIXING TODAY WITH LOUSY LOW LEVEL LAPSE RATES. WHICH AM NOT ENTIRELY SURE ABOUT. INITIAL QUESTION TO HELP WITH THAT WILL BE HOW MUCH CLOUD COVER WILL MOVE IN TODAY. IMPRESSIVE CLOUD SHIELD OUT TO OUR WEST. THE BETTER MODELS IN REGARDS TO THIS MOISTURE WOULD SAY THAT THE CLOUDS REALLY DO NOT THICKEN UP UNTIL THIS AFTERNOON. HOWEVER...DESPITE THE LACK OF MIXING WHAT MAY BE THE MAIN DRIVING FORCE BEHIND THESE WINDS COULD THE TIGHTENING PRESSURE GRADIENT AND PRETTY HIGH 3 HOUR PRESSURE FALLS THROUGH THE AFTERNOON. GOING BY WHAT LIMITED MIXING BUFKIT SHOWS...WINDS LOOK TO REACH ADVISORY CRITERIA. IT WILL BE CLOSE BUT CHOSE TO ISSUE A WIND ADVISORY FOR ALL BUT THE FAR EASTERN TWO COUNTIES. ADVISORY MAY BE MARGINAL FOR THOSE EASTERN COUNTIES BUT WILL BE PLAYING THIS ON THE SAFE SIDE. MODELS HAVE HAD A HORRIBLE TIME WITH TEMPERATURE GRADIENT ACROSS THE AREA. THICKENING CLOUD COVER WILL MAKE THIS EVEN MORE PROBLEMATIC. LOW LEVEL THERMAL PROFILES CLUSTER AROUND A LITTLE WARMER TEMPERATURES THAN WHAT IS IN THERE. CANADIAN SURFACE TEMPERATURE MATCHES UP WELL WITH WHAT THE HRRR IS SHOWING. SO WARMED UP TEMPERATURES SOME IN LINE WITH THOSE MODELS. STRONG INCOMING SYSTEM BEGINS TO AFFECT THE AREA LATE TONIGHT. DEEPER MOISTURE AND LIFT ALONG WITH DECENT LAPSE RATES COME INTO THE WEST LATE. MORE MODEL QPF SHOWING QPF IN THIS AREA AND SEEMS REASONABLE CONSIDERING THE LIFT AND INSTABILITY. QUESTION THEN BECOMES PHASE. LOW LEVEL THERMAL GUIDANCE AND SOUNDING SHOW VERY MILD OVERNIGHT TEMPERATURES IN ADVANCE OF THE SYSTEM. THE ONLY PLACE THAT LOOKS TO BE NEAR FREEZING IS IN THE EAST WHERE PRECIPITATION IS NOT EXPECTED AT THIS TIME. RAISED MINS ACROSS THE REMAINDER OF THE AREA. CONSIDERING THE POSSIBILITY OF A LITTLE MORE INTENSE PRECIPITATION AND BEING A LITTLE WARM...DID A RAIN AND SNOW MIX IN THE FAR WEST WITH SPRINKLES TO THE EAST OF THERE. SUNDAY/SUNDAY NIGHT...LEFT FRONT QUADRANT OF THE JET STARTS OUT OVER THE EASTERN HALF OF THE AREA AT 12Z AND THEN IT QUICKLY MOVES EAST. STRONG UPPER TROUGH MOVES THROUGH DURING THE DAY. BASED ON SATELLITE...STRONG JET ASSOCIATED WITH THE SYSTEM...AND STRONG PV ANOMALY INDICATED...BELIEVE THE MODELS ARE UNDERDOING THE STRENGTH OF THE SYSTEM. COMBINATION OF STRONG LIFT/PV ANOMALY AND FAVORABLE THETA-E LAPSE RATES...WILL BRING A GOOD CHANCE OF A LIGHT MEASURABLE PRECIPITATION EVENT TO THE AREA. BASED ON THE PREVIOUS REASONING... GEFS PROBABILITIES...AND LOCAL POP PROGRAM...RAISED POPS OVER THE ENTIRE FORECAST AREA...ESPECIALLY IN THE EAST. DAY SHIFT WILL HAVE TO LOOK AT RAISING THESE POPS EVEN MORE. PHASE REMAINS A PROBLEM. MODELS DO NOT SHOW A LOT OF COLD AIR. IT IS POSSIBLE WITH THE MOST INTENSE PRECIPITATION SNOW COULD MIX WITH THE RAIN IN THE MORNING. AT THIS TIME KEPT THE MIXED PHASE IN THE MORNING WITH ALL RAIN IN THE AFTERNOON. HOWEVER...WHAT LOOKS TO BE THE MAIN STORY WILL ONCE AGAIN BE THE WINDS. STRONG SUBSIDENCE BEHIND THE WAVE/EXITING PRECIPITATION COMBINED WITH VERY GOOD LAPSE RATES AND 3 HOUR PRESSURE RISES SHOULD BRING A HIGH END WIND ADVISORY EVENT TO THE ENTIRE AREA. HOWEVER...STRONGEST 3 HOUR PRESSURE RISES ARE OUT AHEAD OF THE MAIN SUBSIDENCE. WHAT IS CONCERNING IS THAT IF PARAMETERS CAN COME TOGETHER A LITTLE BETTER...IT IS POSSIBLE THAT WARNING CRITERIA COULD BE MET. DAY SHIFT WILL HAVE TO LOOK AT THIS AGAIN...AND CHOOSE THE APPROPRIATE HIGHLIGHT. CHOSE TO GO SLIGHTLY BELOW THE GUIDANCE WHICH WAS IN PRETTY CLOSE AGREEMENT. PRECIPITATION SHOULD BE DONE BY THE NIGHT AND WILL PROBABLY COOL BELOW GUIDANCE. MONDAY/MONDAY NIGHT...QUESTION WILL BE HOW MUCH TO WARM TEMPERATURES. WILL HAVE A COLD START PLUS EXITING SURFACE HIGH AND DEVELOPING LEE TROUGH WILL CAUSE THE WINDS TO BE MORE FROM AN UPSLOPE DIRECTION. SO TRENDED SLIGHTLY COOLER THAN THAN GUIDANCE. NEXT FRONT STARTS MOVING THROUGH DURING THE NIGHT AND MADE NO CHANGES TO THE TONIGHT PERIOD. BULLER TUESDAY THROUGH FRIDAY...SHORTWAVE RIDGE BREAKS DOWN AS TROUGH OVER GREAT BASIN SHIFTS EAST ACROSS THE INTERMOUNTAIN WEST. GUIDANCE IN GENERAL AGREEMENT ON H5 CLOSED LOW DEVELOPING OVER NEW MEXICO TUESDAY MORNING...WITH SHORTWAVE TROUGH KICKING EAST ACROSS THE CWA BY 18Z TUESDAY. MOISTURE ISNT VERY IMPRESSIVE WITH THIS SYSTEM... WITH CLOSED LOW KEEPING GULF MOISTURE MUCH FURTHER SOUTH. HOWEVER THERE IS A NARROW WINDOW WHERE LARGE SCALE ASCENT AND LIMITED MOISTURE ADVECT IS PRESENT OVER PARTS OF THE CWA. FOR NOW HAVE KEPT SLIGHT CHANCE POPS ACROSS WESTERN LOCATIONS DURING THE DAY TUESDAY... AND IN THE FAR EASTERN DURING THE EVENING. SHORTWAVE RIDGE DEVELOPS ACROSS THE SW US WEDNESDAY AND THURSDAY AS TROUGH SHIFTS EAST...WITH NW FLOW JUST NORTH OF THIS FEATURE OVER THE CWA. LEE TROUGH DEVELOPS THURSDAY BENEATH THIS PATTERN WITH S/SW FLOW AT THE SURFACE SUPPORTING A BRIEF RETURN TO TEMPS IN THE 50S/NEAR 60 THURSDAY AFTERNOON. NW FLOW PERSISTS THROUGH FRIDAY...WITH SHORTWAVE TROUGH PUSHING EAST TOWARDS THE PLAINS FRIDAY NIGHT. GUIDANCE IS ALL OVER THE PLACE ON THE EXACT TRACK OF THIS FEATURE...SO NOT ENOUGH CONFIDENCE TO ADD PRECIP AT THIS POINT. DR THANKS TO ALL THAT COLLABORATED. && .AVIATION... 1039 AM MST SAT JAN 21 2012 FOR THE 18Z TAFS...GUSTY WINDS WILL IMPACT THE TERMINALS TODAY AND TOMORROW...AND THERE IS ALSO THE POSSIBILITY OF PRECIPITATION TOMORROW. FOR TODAY...GIVEN THE POSITION OF KGLD RELATIVE TO THE LEE TROUGH...HAVE INCLUDED STRONGER WINDS AT KGLD COMPARED TO KMCK. WINDS WILL WEAKEN TONIGHT...BUT GUSTS ARE EXPECTED TO CONTINUE FOR A FEW HOURS TONIGHT AT KGLD AS THE LEE TROUGH WEAKENS. AS AN UPPER TROUGH MOVES OVER THE AREA...WINDS WILL SHIFT TO NORTHWESTERLY AND INCREASE DURING THE MID MORNING. THE TROUGH WILL ALSO BRING THE POSSIBILITY OF A LIGHT RAIN/SNOW MIX TO THE TERMINALS. CONFIDENCE ABOUT PRECIP IS HIGHER AT KMCK...AND WHILE NAM SOUNDINGS ALSO SUPPORT MVFR CEILINGS AT KMCK...IT IS MORE LIKELY THAT CEILINGS WILL REMAIN IN THE LOW VFR RANGE. THE WIND COULD CAUSE VISIBILITIES LOWER THAN VFR WHEN COMBINED WITH LIGHT PRECIP...ESPECIALLY IF SNOW ENDS UP DOMINATING...BUT CONFIDENCE TOO LOW AT THIS TIME TO INCLUDE SUB-VFR CONDITIONS. CJS && .GLD WATCHES/WARNINGS/ADVISORIES... KS...WIND ADVISORY UNTIL 6 PM MST /7 PM CST/ THIS EVENING FOR KSZ001>003-013>015-027>029-041-042. FIRE WEATHER WATCH FROM SUNDAY MORNING THROUGH SUNDAY AFTERNOON FOR KSZ013-027-041. NE...WIND ADVISORY UNTIL 6 PM MST /7 PM CST/ THIS EVENING FOR NEZ079>081. CO...WIND ADVISORY UNTIL 6 PM MST THIS EVENING FOR COZ090>092. FIRE WEATHER WATCH FROM SUNDAY MORNING THROUGH SUNDAY AFTERNOON FOR COZ252>254. && $$
AREA FORECAST DISCUSSION
NWS TOPEKA KS
1133 AM CST SAT JAN 21 2012 ...UPDATE TO AVIATION... .DISCUSSION... WEAK UPPER TROF WAS EXITING EASTERN KANSAS EARLY THIS MORNING WHILE MUCH STRONGER WAVE WAS APPROACHING THE WEST COAST PER WATER VAPOR IMAGERY. SURFACE RIDGE AXIS REMAINS ACROSS CENTRAL KANSAS..WITH WIDESPREAD STRATUS OOZING SOUTHWEST JUST AHEAD OF IT INTO EAST CENTRAL KANSAS...AND MORE SCATTERED LOW CLOUD TO ITS NORTHWEST IN NORTH CENTRAL KANSAS AND EASTERN NEBRASKA. STRONG PRESSURE FALLS WERE OCCURRING IN THE NORTHERN HIGH PLAINS UNDER QUICK ZONAL FLOW ALOFT. LATEST RUC SEEMS TO BE DOING FAIRLY WELL WITH LOW CLOUD TRENDS...AND SEEMS REASONABLE WITH STRATUS CONTINUING SOUTHWEST THROUGH EAST CENTRAL KANSAS...BUT MAKING LITTLE PROGRESS ELSEWHERE. SHOULD SEE MOSTLY CLEAR SKIES TAKE HOLD BY LATE MORNING. SOUTH WINDS WILL DEVELOP THIS AFTERNOON AS THE RIDGE PUSHES EAST WITH TEMPERATURES RISING TO AROUND FREEZING. LITTLE IN THE WAY OF DIURNAL TEMP FALLS EXPECTED TONIGHT WITH TIGHT PRESSURE GRADIENT DEVELOPING IN EASTERN KANSAS UNDER 30-50KT SOUTH 925MB WINDS. MODEST LOW LEVEL MOISTURE SHOULD RESULT IN STRATUS INTRUSION IN AT LEAST EASTERN AREAS. MAIN FOCUS FOR THE EARLY PERIODS IS STILL THE UPPER TROFS SPEED AND STRENGTH AS IT PASSES THROUGH THE PLAINS SUNDAY AND SUNDAY NIGHT. SIMILAR TO RUNS OF THURSDAY NIGHT...THE NAM IS ON THE QUICK SIDE...ECMWF ON THE SLOW SIDE...AND OTHERS IN BETWEEN. HAVE SIDED CLOSEST TO THE LARGER DOMAIN MODELS THINKING THEY SHOULD HAVE THE BEST HANDLE ON THIS OFF-SHORE SYSTEM...SPECIFICALLY CLOSEST TO THE ECMWF AND GEM. THIS DELAYS THE BEST PRECIPITATION CHANCES TO LATE SUNDAY AFTERNOON AND INTO SUNDAY EVENING. 850MB TEMPS RISE INTO THE 10-12C RANGE TONIGHT...AND DESPITE STRONG AND DEEP COLD AIR ADVECTION WITH THIS SYSTEM...CHANGEOVER TO AN ALL SNOW TYPE SHOULD BE DELAYED UNTIL SUNDAY EVENING. PRECIP WILL LIKELY COINCIDE WITH STRONG NORTHWEST WINDS BEHIND THE PACIFIC FRONT...BUT PRECIP RATES/AMOUNTS AND SPEEDS SHOULD BE LOW ENOUGH TO PRECLUDE ANY HEADLINES. DEEPER MIXING BEHIND THE SYSTEM MONDAY SHOULD PUSH HIGHS BACK INTO THE 40S. TREND FOR THE TUESDAY INTO WEDNESDAY PERIODS CONTINUES TO BE FOR BULK OF ENERGY WITH THE NEXT SHORTWAVE TO DIVE SOUTHEAST...WITH LITTLE FORCING FOR PRECIPITATION THIS FAR NORTH. THERE REMAINS SOME SIGNAL FOR LIGHT AND SPOTTY ACCUMS TO OCCUR...AND SOME MENTION WILL REMAIN FOR TUESDAY AFTERNOON IN THE WEST AND AREA-WIDE TUESDAY NIGHT. TEMPERATURE PROFILES SHOULD SUPPORT RAIN-SNOW AGAIN. ZONAL FLOW SHOULD MAINTAIN ITSELF NORTH OF THE UPPER LOW WITH SOMEWHAT ABOVE NORMAL TEMPS RESULTING. 65 && .AVIATION... MVFR STRATUS DECK HAS BEGUN TO VERY SLOWLY ERODE ON THE WESTERN FRINGES AND EXPECT THE CIGS TO SCATTER OUT FIRST AT MHK AND THEN AT TOP/FOE THIS AFTERNOON. EXACT TIMING IS UNCERTAIN BUT HIGHLIGHTED MOST LIKELY TIMING WITH A TEMPO GROUP. EXPECT A PERIOD OF VFR CONDITIONS FROM THAT POINT THROUGH 09Z-11Z WHEN LOW STRATUS IS AGAIN EXPECTED TO DEVELOP ALONG WITH SOME MINOR VIS RESTRICTIONS. HIGHER CONFIDENCE IN CIGS AT TOP/FOE THAN MHK BUT POTENTIAL EXISTS FOR MVFR...TO PERHAPS IFR CIGS BY SUNRISE SUNDAY MORNING. THIS SHOULD THEN LAST THROUGH THE END OF THE TAF PERIOD. BARJENBRUCH && .TOP WATCHES/WARNINGS/ADVISORIES... NONE. && $$
AREA FORECAST DISCUSSION
NWS CARIBOU ME
1201 PM EST SAT JAN 21 2012 .SYNOPSIS... LOW PRESSURE WILL TRACK SOUTH OF THE GULF OF MAINE TODAY. HIGH PRESSURE WILL THEN BUILD ACROSS THE REGION SUNDAY AND MOVE EAST OF THE AREA EARLY MONDAY. & .NEAR TERM /THROUGH TONIGHT/... UPDATE2: WITH SNOW JUST WEST OF OUR FORECAST AREA, WILL INCREASE POPS TO LIKELY ALONG THE COAST FOR THE REMAINDER OF THIS AFTERNOON. ANY SNOW ACCUMULATION STILL APPEARS TO BE LESS THAN AN INCH. UPDATE1: HRRR MODEL STILL INDICATING NORTHERN EDGE OF SNOW WILL MOVE ACROSS DOWNEAST THIS AFTERNOON WITH A PERIOD OF LIGHT SNOW SO WILL KEEP POPS GOING FOR DOWNEAST TODAY. ANY SNOW ACCUMULATION WILL BE LESS THAN AN INCH. PREV DISC: LOW PRESSURE WILL TRACK SOUTH OF NEW ENGLAND TODAY. THE PRECIPITATION FROM THIS SYSTEM IS ONLY EXPECTED TO EFFECT THE SOUTH. HAVE USED A BLEND OF THE NAM12...GFS40 AND SREF FOR POPS. WILL ADJUST THIS BLEND MANUALLY TO KEEP LOWER POPS FURTHER SOUTH. HAVE USE A BLEND OF NAM12 AND GFS40 FOR WIND. HIGH PRESSURE WILL BUILD IN FROM THE NORTHWEST SUNDAY. FOR TEMPERATURE AND DEW POINT WILL USE GMOS AND ADJUST LOW TEMPERATURE LOWER SUNDAY MORNING TO ACCOUNT FOR RADIATIONAL COOLING. FOR QPF HAVE BLENDED THE NAM12 AND GFS40. && .SHORT TERM /SUNDAY THROUGH MONDAY/... A THAW LOOKS TO BE IN ORDER COME MONDAY W/LOW PRES MOVING THROUGH THE WESTERN QUEBEC PROVINCE. A NICE DAY IS IN STORE FOR SUNDAY W/A A GOOD DEAL OF SUNSHINE AS HIGH PRES SETTLES RIGHT ACROSS THE STATE. TEMPERATURES WILL BE WARMER THAN THEY WERE SATURDAY HITTING THE MID/UPPER TEENS NORTH AND LOW TO MID 20S ACROSS THE CENTRAL AND DOWNEAST REGION. HIGH PRES WILL SLIDE E SUNDAY NIGHT W/A RETURN FLOW FROM THE ESE BEGINNING TO SETUP. HIGH CLOUDINESS IS SHOWN BY THE GFS AND THE NAM TO MOVE ACROSS THE REGION SUNDAY NIGHT AS WAA BEGINS TO SET UP. TEMPERATURES WILL DROP BACK IN THE EVENING AND THEN ARE SHOWN TO LEVEL OFF BEFORE RISING EARLY MONDAY MORNING. ATTM, STAYED CLOSE TO THE DAYCREW/S ASSESSMENT OF SINGLE NUMBERS ACROSS THE NORTHERN AND WESTERN SECTIONS AND LOW TO MID TEENS FOR THE CENTRAL AND DOWNEAST REGIONS. THIS WILL NEED TO BE LOOKED AT AGAIN AS ANY PROLONGED CLEARING WILL ALLOW FOR TEMPERATURES TO FALL OFF MORE BEFORE LEVELING OFF. INCREASING CLOUDS FOR MONDAY W/A SSE FLOW SETTING UP AND MOISTURE GETTING PULLED NORTHWARD. STRATUS LOOKS LIKE IT COULD ADVECT IN W/THIS SETUP. ECMWF HOLDS ON TO LLVL COLD AIR LONGER W/DAMMING ACROSS THE ENE SECTIONS OF THE CWA. THE NAM AND THE CANADIAN HEMISPHERIC INDICATE THIS TO BE THE CASE AS WELL. THE GFS BREAKS DOWN THE DAMMING QUICKER. THEREFORE, DECIDED TO CUT BACK MAXES ON MONDAY W/THE SETUP PLUS WARMING TENDS TO HOLD BACK A BIT W/A SE FLOW GETTING STARTED(HISTORICALLY SPEAKING). PRECIP CHANCES WERE HELD BACK SOME W/RIDGE HOLDING IN LONGER. LOOKS LIKE SOME MIX OF RAIN/SNOW AND SLEET INITIALLY LATE MONDAY ACROSS THE NORTH AND WEST W/RAIN OVER THE DOWNEAST AND POINTS SOUTH. TEMPERATURES WILL CONTINUE TO SLOWLY RISE MONDAY NIGHT AND THIS WILL BE ADDRESSED BELOW. && .LONG TERM /MONDAY NIGHT THROUGH FRIDAY/... THE MAIN CHALLENGE THIS TERM WILL BE TEMPERATURES AND PRECIP TYPE EARLY IN THE TERM. OCCLUSION IS SHOWN BY THE LONG RANGE GUIDANCE INCLUDING THE CANADIAN HEMISPHERIC TO LIFT NORTHWARD MONDAY NIGHT AND SWING ACROSS THE REGION ON TUESDAY. THE NAM/ECMWF SHOW A WEAK LOW DEVELOPING ON THE OCCLUSION AND MOVING ACROSS EASTERN MAINE. THIS COULD ENHANCE PRECIP AND POSSIBLY CUT OFF SIGNIFICANT WARMING WHILE THE CANADIAN HEMISPHERIC HINTS AT SOMETHING SIMILAR BUT IS FURTHER WEST WHICH WOULD ALLOW FOR MORE WARMER AIR TO BE PULLED NORTHWARD. THE GFS AND ITS ENSEMBLE MEAN KEEP THE OCCLUSION SWEEPING THROUGH THE REGION ON TUESDAY. DAYCREWS POPS LOOKED GOOD AND MODIFICATIONS MADE ONLY FOR PLACEMENT AND BROUGHT THE VALUES UP SOME BUT STILL IN THE LIKELY TO CATEGORICAL RANGE. SOME SLEET AND RAIN POSSIBLE ACROSS THE FAR NORTH EARLY MONDAY EVENING BUT THE COLUMN SHOULD BE WARM ENOUGH TO ALLOW FOR RAIN. AN INTERESTING NOTE IS THAT THE HEMISPHERIC GUIDANCE SHOWS 40S AND 50S TUESDAY AFTERNOON. THIS IS THE ONLY GUIDANCE THAT IS SHOWING THIS TO BE THE CASE. A BLEND OF THE GMOS AND GFS WAS USED FOR THE TEMPERATURES WHICH INDICATE A WARMER SCENARIO FOR TUESDAY W/TEMPERATURES HITTING THE MID AND UPPER 30S NORTH AND WEST AND 40S CENTRAL AND DOWNEAST. THE FRONT CLEARS THE REGION BY TUESDAY EVENING W/THE GRADUAL COOL DOWN AND WHATEVER PRECIP IS LEFTOVER TRANSITIONING TO SNOW SHOWERS MAINLY NORTH & WEST. HELD BACK THE COOLING FOR ABOUT 6 HRS AS PAST EVENTS SIMILAR TO THIS SHOW MODELS TO BE TOO FAST W/BRINGING THE COLDER AIR BACK IN BEHIND THE OCCLUSION. UPPER TROF WILL NEED TO MOVE THROUGH FOR THAT TO HAPPEN. GMOS/GFS TEMPERATURES WERE BLENDED FOR TUESDAY NIGHT AS WELL. THE ASSOCIATED COLD FRONT WILL MAKE ITS WAY ACROSS THE CWA ON WEDNESDAY W/MUCH COLDER TEMPERATURES FOR MID TO LATE WEEK AS ADVERTISED BY THE GFS AND ECMWF. GMOS WAS USED FROM WEDNESDAY ONWARD BUT PULLED BACK POPS TO BELOW 20% THURSDAY INTO FRIDAY W/HIGH PRES BUILDING ACROSS THE REGION. ECMWF BRINGS A LOW ACROSS THE GULF OF MAINE LATE NEXT FRIDAY W/AN INVERTED TROF HANGING BACK ACROSS THE REGION SIMILAR TO THIS PASS EVENT YESTERDAY(FRIDAY1/20). THIS WOULD MEAN POTENTIAL SNOW FOR THE CWA. THE ECMWF IS THE ONLY GUIDANCE SHOWING THIS AS THE GFS AND ITS ENSEMBLES SHOW THE LOW TO DEVELOP WELL SOUTH OF THE CWA. STILL PLENTY OF TIME TO LOOK AT THIS AS THIS IS DAY 7!. && .AVIATION /16Z SATURDAY THROUGH WEDNESDAY/... NEAR TERM: MAINLY VFR CONDITIONS TODAY AND TONIGHT EXCEPT FOR A PERIOD OF MVFR IN LIGHT SNOW ACROSS DOWNEAST TERMINALS LATE MORNING INTO EARLY AFTERNOON. SHORT TERM: VFR FOR SUNDAY AND THEN POTENTIAL FOR MVFR/IFR ON MONDAY W/SSE FLOW SETTING UP W/MOISTURE GETTING PULLED IN FROM THE ATLC OCEAN. MONDAY NIGHT INTO TUESDAY LOOK TO BE IFR AND EVEN LIFR AT LEAST EARLY IN THE DAY. LLWS ALSO A POSSIBILITY EARLY TUESDAY. && .MARINE... NEAR TERM: AS LOW PRESSURE MOVES SOUTHEAST OF THE WATERS, MAY HAVE A PERIOD OF SCA WINDS ON THE BACK SIDE OF THE LOW PRESSURE TONIGHT MAINLY OVER OUR OUTER WATERS. SHORT TERM: SCA CONDITIONS BY MONDAY W/POTENTIAL FOR A BRIEF PERIOD OF GALES EARLY TUESDAY W/THE OCCLUSION. USED THE NAM12 AND GFS THROUGH EARLY TUESDAY WHICH SUPPORTS GUSTS HITTING 35+ KTS FROM 12-18Z TUESDAY AS LLVL JET OF 50 KTS IS SHOWN TO PASS OVER THE WATERS. HELD ONTO THE DAYCREWS WAVE HEIGHTS OF INCREASING SEAS TO 10-13FT BY TUESDAY W/SSE FLOW. FOLLOWED WNAWAVE FROM TUESDAY NIGHT INTO WEDNESDAY SHOWING A DECREASING TREND IN SEAS. && .CAR WATCHES/WARNINGS/ADVISORIES... ME...NONE. MARINE...SMALL CRAFT ADVISORY FROM 9 PM THIS EVENING TO 4 AM EST SUNDAY FOR ANZ050-051. && $$ NEAR TERM...FOSTER/MIGNONE SHORT TERM...HEWITT LONG TERM...HEWITT AVIATION...FOSTER/MIGNONE MARINE...FOSTER/MIGNONE/HEWITT
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
352 PM EST SAT JAN 21 2012 .SYNOPSIS... 12Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW WNW FLOW ALF OVER THE UPR LKS BTWN ARCTIC VORTEX CEMTERED OVER HUDSON BAY ASSOCIATED WITH RECENT INTENSE CHILL AND PROGRESSIVE UPR RDG SHIFTING E THRU THE NRN PLAINS. SFC/H85 RDG AXIS HAS BROUGHT RELATIVELY TRANQUIL WX TO THE FA TDAY WITH MID LVL DRY AIR SHOWN ON THE 12Z GRB RAOB. TEMPS HAVE RISEN STEADILY FM MRNG LOWS ARND -25F OVER THE INTERIOR W. SOME LES LINGERS EARLY THIS AFTN OVER THE KEWEENAW AND IN AREAS WELL E OF MQT WITH H85 TEMPS STILL AOB -15C...BUT BACKING LLVL FLOW TO THE SW THAT SIGNALS A RETREAT OF THE ARCTIC AIR IS CAUSING THE SHSN TO DRIFT TO THE NE. IN FACT...WAD MID CLD BEST DEPICTED BY THE RH SHOWN ON THE 12Z NAM 290-295K ISENTROPIC SFCS/H6-7/ AND WELL IN ADVANCE OF SHARP H85 WARM FNT PUSHING THRU THE NRN PLAINS IS ALREADY MOVING FM NRN MN INTO THE WRN CWA. BUT GENERALY DRYNESS OF THE 12Z INL RAOB IS PREVENTING ANY PCPN. SOME -SN IS SHOWING UP NEAR LK WINNIPEG. TO THE S...THERE IS QUITE A BIT OF LO CLD S OF THE HI CENTER IN WI...AND THIS ST/SC IS STARTING TO STREAM NWD INTO SW MN. FARTHER W...12Z H85 TEMPS WERE UP TO 6C IN THE LEE OF THE ROCKIES BEHIND THE WARM FNT. A VIGOROUS SHRTWV IS DIGGING SEWD INTO THE SW STATES. THERE HAVE BEEN A FEW LTG STRIKES NEAR THE TRACK OF THIS FEATURE...AND NEARBY PIREPS INDICATE H3 WIND SPEEDS UP TO 175KT WITHIN SUPPORTING UPR JET THAT IS WELL DEFINED ON WV IMAGERY. && .SHORT TERM DISCUSSION /TNGT AND SUN/... MAIN FCST CONCERNS IN THIS PERIOD ARE IMPACT OF RETURNING WARM AIR IN VIGOROUS WAD PATTERN THAT WL SET UP IN RETURN SLY FLOW BTWN DEPARTING HI PRES RDG TO THE E AND DVLPG LO PRES IN THE PLAINS ASSOCIATED WITH VIGOROUS HGT FALLS IN ADVANCE OF SHRTWV NOW MOVING INTO THE SW STATES. TNGT...WITH STRENGTHENING LLVL SLY FLOW...EXPECT ANY LES NEAR LK SUP TO DRIFT OFFSHORE BY LATE IN THE AFTN. SINCE THE AIRMASS WL STILL BE COLD ENUF FOR LES EARLY WITH H85 TEMPS ARND -12C...GOING FCST OF SOME LK CLD/SHSN OFF LK MI INTO THE FM ISQ-ERY STILL LOOKS ON TRACK. BUT THIS PCPN SHOULD DIMINISH AS TEMPS RISE THRU THE NGT. IN FACT... H85 WIND INCRSG UP TO 50KTS TOWARD WRN LK SUP BY 12Z SUN ARE FCST TO PUSH H85 TEMPS NEAR 0C IN THAT AREA TOWARD DAYBREAK. THIS STRENGTHENING SSW FLOW WL ALSO DRAW THE LO CLD NOW WELL TO THE S INTO THE WRN AND CNTRL CWA. BUT DOWNSLOPE NATURE OF THE FLOW OVER THE W AND NCNTRL SHOULD RESULT IN SOME DISSIPATION OF THIS CLD COVER. TO THE NW...THE AREA OF SN NOW NEAR LK WINNIPEG WL LIKELY SHIFT NEAR ISLE ROYALE WITH PERSISTENT ISENTROPIC ASCENT SHOWN ON THE 290-295K SFCS...MORE SATURATED PROFILE DOWN TO THE SFC...AND INCRSG UPR DVGC IN RRQ OF H3 JET MAX IN ONTARIO AND IN EXIT REGION OF ANOTHER UPR JET EMERGING ON THE E SIDE OF DEEPENING UPR TROF IN THE PLAINS. WITH 5-6K FT DEEP DRY WEDGE SHOWN ON FCST SDNGS FOR CMX...SUSPECT THE BULK OF THIS PCPN WL REMAIN TO THE NW OF THE KEWEENAW. SO CUT POPS INTO THE CHC CATEGORY FOR THAT AREA WITH HIER POPS TO THE N. EXPECT THE LOWEST TEMPS EARLY TNGT...WITH THE MERCURY RISING LATER AS INCRSG S WIND ADVECTS MORE LLVL MSTR INTO THE AREA. TENDED TO LOWER EARLY EVNG TEMPS OVER THE INTERIOR CNTRL BEFORE ARRIVAL OF THICKER CLD COVER/ONSET OF STRONGER WINDS CAUSES TEMPS TO RISE OVERNGT. SUN...THE WX WL BE DOMINATED BY THE ARRIVAL OF INCRSG LLVL MSTR IN STEADY SSE WIND BTWN DEPARTING HI PRES RDG AND DVLPG LO IN THE PLAINS. ALTHOUGH CONTINUED WAD WL TEND TO RESULT IN INCRSG MID LVL MSTR AS WELL...MODEL GUIDANCE INDICATES A PERSISTENT DRY WEDGE CENTERED ARND H85 THRU THE DAY BTWN THE LLVL AND HIER LVL MOISTENING. MAINTAINED MAINLY SCHC POPS FOR LARGER SCALE PCPN...HIER TO THE NW. ANY PCPN WL LIKELY BE SN AND PSBLY SLEET WITH WARM WEDGE/H85 TEMPS POTENTIALLY UP TO 5C IN THE DRY LYR THAT MIGHT MELT SN FLAKES ABV RESIDUAL COLD AIR JUST ABV THE SFC...WHERE TEMPS ARE FCST TO REMAIN AS LO AS -6C TO -8C. ALSO INCLUDED MENTION OF FZDZ MAINLY OVER THE SCNTRL WHERE GUIDANCE SHOWS INCRSG SFC DEWPTS IN AREA OF UPLSOPE SSE FLOW. LIMITING FACTOR WL BE FAIRLY HI SFC DEWPT DEPRESSIONS NOW OBSVD TO THE S/STRONG WINDS THAT MIGHT MAINTAIN A SLIGHT INVERTED V LLVL THERMAL/MSTR PROFILE. .LONG TERM /SUNDAY NIGHT THROUGH NEXT SATURDAY/... DEEPENING LOW PRESSURE OVER THE UPPER LAKES AND MIXED PRECIPITATION ISSUES IS THE MAIN CONCERN OF THE LONG TERM. BY SUNDAY EVENING...SHORTWAVE TROUGH WITH AT LEAST TWO EMBEDDED SHORTWAVES/PV ANOMALIES WILL BE OVER THE CNTRL PLAINS. MAJORITY OF MODELS AGREE IN THIS IDEA. 12Z NAM IS ON ITS OWN SHOWING STRONGER PIECE OF ENERGY SHOOTING NORTH INTO MN. ALL OTHER GUIDANCE...SAVE THE SREF WHICH HAS MANY NAM MEMBERS WITHIN IT...KEEPS STRONGEST ENERGY MORE OVR SOUTHERN PLAINS. BASED ON POSITION OF UPPER JET AHEAD OF TROUGH...THINK NAM IS TOO STRONG WITH SHORTWAVE OVR MN. THIS LEADS TO A MUCH FARTHER NORTH TRACK TO SFC LOW ON MONDAY (NORTHERN LK SUPERIOR MONDAY MORNING INSTEAD OF OVR SOUTHERN LK MICHIGAN). SO AS MUCH AS WOULD HAVE LIKED TO HAVE THE HIGHER RESOLUTION NAM THERMAL PROFILES TO USE IN THIS FCST...HAVE TO DISCOUNT THE NAM AT THIS TIME. SHOULD NOTE THAT IT APPEARS THE 12Z NAM IS TRENDING TOWARD MAJORITY OF OTHER MODELS...SO MAYBE IT WILL BE MORE USEFUL IN 24 HRS. MOVING ON THAT LEAVES THE ECMWF AND UKMET IDEA (WHICH HAVE BEEN CONSISTENT AND PREFERRED WITH THIS SYSTEM FOR SOME TIME NOW) AS WELL AS THE GFS WHICH BEGAN TRENDING TOWARD ECMWF/UKMET IDEA WITH THE 18Z RUN ON 1/20. CANADIAN ALSO PRETTY MUCH IN LINE NOW AS WELL...THOUGH RUN-TO-RUN CONSISTENCY WITH SFC LOW TRACK ON MONDAY STILL NOT THE GREATEST. SHOULD NOTE...12Z GFS DID TREND A BIT TOWARD NAM IDEA AND WAS NOT PREFERRED BY HPC. 12Z ECMWF/CANADIAN/UKMET REMAIN CONSISTENT WITH PREVIOUS MODEL RUNS. APPEARS THAT THOUGH THERE IS SOME INTERACTION WITH NORTHERN STREAM LATER MONDAY AND MONDAY NIGHT...THIS SYSTEM WILL BE MAINLY SOUTHERN STREAM ORIGIN. WITH THAT WILL COME GOOD TAP OF GULF MOISTURE WITH PWATS OVR 250 PCT OF NORMAL BY 12Z MONDAY OVR MOST OF THE CWA. POSITION OF H85 TROUGH AND SRLY H85 WINDS PUT STRONGEST H85 THETA-E ADVECTION OVER EAST HALF OF CWA BTWN 09Z-15Z MONDAY. HEAVIEST QPF IS FCST OVR CNTRL AND EAST CWA. RUN TOTAL QPF THROUGH 00Z TUESDAY (WHEN DEEPER MOISTURE/HIGHER PWATS SHIFT TO THE NORTHEAST INTO ONTARIO/QUEBEC) RANGE FROM 0.50-0.90 OF AN INCH WITH CANADIAN UP OVR 1 INCH...HEAVIEST CNTRL CWA DUE TO DEFORMATION ON BACK EDGE OF H85-H7 LOWS AND IT IS ALSO WHERE THERE IS A HINT OF A TROWAL HANGING BACK OVR THE AREA AS H85-H7 LOWS MAINTAIN STEADY STRENGTH WHILE HEADING INTO ONTARIO. LOW-LEVEL THERMAL PROFILES WILL BE CRITICAL COMPONENT WITH THIS SYSTEM...ESPECIALLY THROUGH NOON ON MONDAY. BASED ON 0C H85 LINE...RAIN WILL BE MAIN PTYPE EAST OF MARQUETTE AND DICKINSON COUNTIES...WITH SNOW TO THE WEST. TROUBLE IS THAT SFC-BLYR TEMPS WILL BE VERY CLOSE TO FREEZING AS THE RAIN ARRIVES FM THE SOUTH LATE SUNDAY NIGHT. COULD EVEN BE SLEET OR SNOW RIGHT AT THE ONSET OF PRECIPITATION SUNDAY NIGHT AS WELL AS COLD AIR ALOFT SLOWLY EVADES. BELIEVE FREEZING RAIN WILL BE BIGGEST CONCERN TOWARD DAYBREAK MONDAY AND THROUGH ABOUT MID MORNING...THEN BLYR WARMING IN THE EAST SHOULD CHANGE PTYPE TO JUST RAIN. DUE TO COLD SPELL LATELY...WARMING OF GROUND SFC TEMPS WILL LAG THE AIR TEMPS...SO MAY BE SITUATION WHERE TEMPS AT OBSERVATION PLATFORMS (ASOS/AWOS/RAWS) ARE IN THE MID 30S BUT THERE IS STILL ICING OCCURRING ON COLDER UNTREATED SURFACES. UNFORTUNATELY...THESE THERMAL QUESTIONS ABOUND THE FIRST PART OF MONDAY WHEN BULK OF HEAVIER QPF IS FCST WITH WARM AIR ADVECTION ALOFT AT ITS PEAK. DO THINK THERE IS A GREATER THAN 50 PCT CHANCE OF SIGNIFICANT ICING LATE SUNDAY NIGHT AND MONDAY MORNING... ESPECIALLY AWAY FM THE IMMEDIATE SHORELINES OF LK SUPERIOR AND LK MICHIGAN. EVENTUALLY...BLYR WARMING WILL RESULT IN MOSTLY RAIN BY LATE MORNING EAST OF MUNISING TO MENOMINEE AS SFC LOW IS FCST TO DEEPEN AND MOVE FM SOUTHEAST WI TO SCNTRL UPR MI AND EVENTUALLY OUT OVR SOUTHEAST LK SUPERIOR BY MONDAY EVENING. SITUATION COULD BECOME VERY FAVORABLE FOR HEAVIER SNOW OVR CNTRL CWA THOUGH...MAINLY OVR HIGHER TERRAIN JUST WEST OF MARQUETTE INTO PORTIONS OF KEWEENAW AND AS FAR SOUTH AS WI BORDER...EVENTUALLY SPREADING INTO ALGER AND DELTA COUNTIES BY LATE AFTN. PRIMARYDRIVER FOR POTENTIALLY HEAVIER SNOW IS VERY TIGHT H85 TEMPERATURE GRADIENT OVR CNTRL CWA/INCREASING DEFORMATION ON WEST SIDE OF CLOSED OFF H85-H7 LOWS AND LINGERING TROWAL REGION MOST NOTED 950-750MB. NORTHERN STREAM WAVE DIGGING INTO THE SOUTHERN STREAM SYSTEM WILL ALSO LEAD TO STRONGER DEFORMATION PRECIP REGION. HEADLINES...GIVEN THIS SYSTEM WILL BE AFFECTING THE AREA ON A MONDAY WHEN THERE IS LOT OF TRAVEL WITH WORK/SCHOOL/ETC AND SINCE THIS SYSTEM HAS POTENTIAL TO BE HIGHER IMPACT DUE TO AMOUNT OF MOISTURE AVAILABLE...THINK GOING WITH A WATCH RIGHT NOW IS A GOOD IDEA. MAIN ISSUE FOR ALGER AND DELTA COUNTY EASTWARD IS THE INITIAL ICE THREAT LATER SUNDAY NIGHT INTO MONDAY MORNING. A MIXED BAG OF ICE AND SNOW AND SOME SLEET IS MAIN ISSUE FOR AREAS OVR CNTRL UPR MI...BASICALLY MARQUETTE AND DICKINSON/MENOMINEE COUNTIES. FARTHER WEST...IT WOULD BE GENERALLY A SNOW EVENT. ONLY PLACE WHERE WINTER STORM WATCH WILL NOT BE ISSUED IS FAR WEST CWA AS MODELS ARE VERY INSISTENT IN SHOWING THEM BEING MISSED BY INITIAL WARM AIR ADVECTION PRECIPITATION LATE SUNDAY NIGHT/MONDAY MORNING AND GENERALLY KEEPING THE PRIMARY DEFORMATION AXIS TO THE EAST OF THOSE AREAS ON MONDAY AFTN/MONDAY EVENING. WATCHES WILL RUN FM LATE SUNDAY NIGHT THROUGH MONDAY EVENING FOR MARQUETTE AND DICKINSON COUNTIES WESTWARD BUT WILL KEEP ENDING TIME SHORTER FARTHER EAST AS MOST PTYPE BY AFTN WILL BE RAIN/DRIZZLE AND SNOW SHOULD NOT BE SIGNIFICANT...ESPECIALLY IN FAR EAST TOWARD KERY. LK EFFECT...POSSIBLY ENHANCED BY DEPARTING SYSTEM WILL TARGET NW FLOW AREAS LATER MONDAY NIGHT INTO TUESDAY MORNING. GUSTY NW WINDS WILL LEAD TO BLSN ISSUES AS WELL. WILL GO AHEAD AND RUN WATCHES THROUGH 12Z WHERE LK EFFECT/BLSN WILL BE HAZARD LATER MONDAY NIGHT. COORD WITH DLH...GRB...APX AND ALSO HPC ON THIS SYSTEM. FOR THE EXTENDED /TUESDAY NIGHT THROUGH SATURDAY/... A SLIGHTLY AMPLIFIED FLOW WITH A BROAD EASTERLY TROUGH AND WEAK WESTERN RIDGE WILL DEVELOP AND LEAD TO A GENERALLY SUSTAINED WNW/NW FLOW OVER THE UPPER GREAT LAKES THROUGH MOST OF THE PERIOD. A SERIES OF SHORTWAVE TROUGHS AND RIDGES WILL PROGRESS ALONG THE WESTERN SIDE OF THE EASTERN TROUGH AND ALLOW FOR PERSISTENT BUT SMALL PRECIP CHANCES. HOWEVER...THERE IS DISAGREEMENT IN THE GUIDANCE WITH THE TIMING OF EACH OF THESE PULSES. CAA ON THE BACKSIDE OF MONDAYS DEPARTING LOW WILL CEASE TUESDAY EVENING AS SFC/850MB WINDS BACK TO THE WEST WITH THE PASSAGE OF A SHARP MID LEVEL RIDGE. SOME LES WILL REMAIN EARLY IN THE EVENING ACROSS EASTERN PARTS OF THE CWA...AND THROUGHOUT THE EVENING IN THE KEWEENAW PENINSULA. THERE WILL BE A BRIEF BREAK AFTER THE RIDGE PASSES BEFORE THE FIRST IMPULSE DIGS SOUTHEAST OUT OF SOUTH CENTRAL CANADA WEDNESDAY NIGHT THROUGH THURSDAY. THE GFS AND ECMWF WERE IN DECENT AGREEMENT WITH THE STRENGTH OF THIS WAVE...BUT THE 12Z GFS HAS TRENDED STRONGER. AT THE SAME TIME...THE GEM HAS NEARLY ZONAL FLOW WEDNESDAY BEFORE DEVELOPING A WEAK SHORTWAVE THURSDAY AFTERNOON. ALL THREE MODELS DO KEEPS MUCH OF THE PRECIPITATION OVER LAKE SUPERIOR AND THE EASTERN HALF OF THE CWA...SO WILL KEEP CHANCES IN THE FORECAST FOR WEDNESDAY NIGHT. ONLY A VERY SHORT PERIOD OF LES...6 TO 12 HOURS...IS POSSIBLE FOR WNW FAVORED WIND BELTS THURSDAY AS BOTH THE GFS AND ECMWF ARE VERY AGGRESSIVE IN BRINGING DRY AIR AND A SHARP LOW LEVEL RIDGE ACROSS LAKE SUPERIOR THURSDAY EVENING. EVEN MORE...RAPIDLY LOWERING INVERSION HEIGHTS TO BELOW 3KFT AND TEMPERATURES BELOW THE INVERSION GENERALLY >-12C WILL LOWER GOOD LES CHANCES. MORE DISAGREEMENT RESIDES WITH THE NEXT WAVE PROGGED TO PASS TO THE NORTH OF THE CWA ON FRIDAY. THE 00Z ECMWF SHOWS AN OPEN WAVE AT 500MB OVER WESTERN ONTARIO 18Z FRIDAY...WHEREAS THE GFS HAS A CLOSED 500MB LOW OVER NORTHERN MANITOBA. THE GFS HAS BEEN RATHER CONSISTENT WITH THIS FEATURE FOR THE LAST DAY WHILE THE ECMWF PULLED THE TROUGH FURTHER SOUTH. ATTM...THE GFS SEEMS TO BE THE BETTER CHOICE...THOUGH BOTH HAVE A COLD FRONT MOVING ACROSS CWA DURING THE DAY FRIDAY. AS THIS OCCURS...THE SURFACE LOW WILL BE TRACKING JUST AHEAD OF THE MIDLEVEL LOW ALONG THE SOUTHWEST SHORE OF HUDSON BAY. NEAR THE CWA THE FORCING WILL BE PURELY FRONTAL...WITH THE STRONGEST BAND OF FRONTOGENESIS NORTH OF LAKE SUPERIOR BETWEEN 500 AND 700MB. THERE IS ALSO CONCERN ABOUT THE LACK OF MOISTURE WITH THIS FRONTAL PASSAGE AS AIR AHEAD OF THE FRONT WILL BE PULLED FROM DRY CONTINENTAL AIR IN THE LEE OF THE NORTHERN ROCKIES. AIR BEHIND THE COLD FRONT ON FRIDAY WILL BE OF WARMER PACIFIC ORIGIN...WITH INVERSION HEIGHTS DROPPING INTO THE EVENING. NW FLOW LES WILL STILL BE A POSSIBILITY...BUT WILL BE GREATLY SUPPRESSED BY LOW INVERSIONS AND HIGH 850/925MB TEMPERATURES. AIR OF MORE ARCTIC ORIGIN COMES IN BEHIND A SECONDARY COLD FRONT ON SATURDAY MORNING...THOUGH MOISTURE IS LACKING WITH THIS FRONT AS WELL. WILL STAY GENERALLY DRY IN TERMS ON POTENTIAL FRONTAL AND LES PRECIP EXCEPT ALONG THE KEWEENAW PENINSULA. && .AVIATION /FOR THE 18Z TAF ISSUANCE/... ALTHOUGH SOME LO CLDS/MVFR CIGS MAY LINGER AT CMX EARLY IN THIS TAF PERIOD...EXPECT THIS LO CLD TO LIFT AWAY TO THE N SOON AFTER TAF ISSUANCE WITH STRENGTHENING S WIND. OTRW...VFR CONDITIONS WILL PREVAIL INTO TNGT. THEN STEADY S WIND WILL ADVECT ABUNDANT LLVL MSTR/LO CLD NOW SHOWING UP WELL TO THE S INTO UPR MI LATE TNGT THRU SUN MRNG. EXPECT DOWNSLOPING WIND COMPONENT AT IWD/CMX TO BREAK UP THE BULK OF THIS CLD IN THOSE LOCATIONS...WITH BETTER CHC OF MVFR CIG IMPACTING THE SAW LOCATION WITH MORE OF AN UPSLOPE WIND COMPONENT THERE. && .MARINE /FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE/... OPTED TO UPGRADE GALE WATCH TO A WARNING OVER THE E PART OF LK SUP FOR LATE TONIGHT THRU SUN WITH STRENGTHENING SLY FLOW UNDER SHARPENING PRES GRADIENT BETWEEN DEPARTING HI PRES RIDGE TO THE E AND DEVELOPING LO IN THE PLAINS. A NNW GALE IS LOOKING MORE LIKELY FOR MON NIGHT/TUE AS DEEPENING LO PRES TRACKING JUST TO THE E MOVES INTO SE CANADA. THE WINDS WILL DIMINISH BY TUE NIGHT WITH APPROACH OF HI PRES RIDGE. ALTHOUGH ANOTHER LO PRES MAY IMPACT THE LAKE ON THU...NO GALES APPEAR LIKELY ATTM. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... WINTER STORM WATCH FROM MONDAY MORNING THROUGH LATE MONDAY NIGHT FOR MIZ001-003-004. WINTER STORM WATCH FROM LATE SUNDAY NIGHT THROUGH LATE MONDAY NIGHT FOR MIZ005-006-011>014-085. WINTER STORM WATCH FROM LATE SUNDAY NIGHT THROUGH MONDAY AFTERNOON FOR MIZ007. LAKE SUPERIOR... GALE WARNING FROM 1 AM TO 7 PM EST SUNDAY FOR LSZ266-267. LAKE MICHIGAN... NONE. && $$ SYNOPSIS...KC SHORT TERM...KC LONG TERM...JLA EXTENDED...TK AVIATION...KC MARINE...KC
AREA FORECAST DISCUSSION
NWS KANSAS CITY/PLEASANT HILL MO
255 PM CST SAT JAN 21 2012 .DISCUSSION... Pesky strato-cu layer finally beginning to erode from the south and west as warmer air aloft and increased mixing eat away at the shallow saturated zone around H9. Only RUC H9 condensation pressure deficit forecasts have accurately depicted this cloud deck today, and show the layer finally giving way just before sunset. Still expecting temperatures to go nowhere this evening, then actually begin a slow climb after midnight with waa and mixing. New stratus layer currently over NE TX/SE OK will advect north with the leading edge of the moisture tongue, and could potentially see some fog and drizzle in this band. However, believe forecast soundings and numerical guidance are underestimating soil temperatures and tend to favor more light fog/haze with dew deposition versus reduced visibilities/drizzle in a well mixed boundary layer. Have introduced a patchy drizzle mention later in the morning as soundings begin to look a bit more favorable (in addition to model qpf output), but not expecting a persistent or widespread drizzle. Rather potent shortwave now crossing the Sierra Nevada will eject into the central plains Sunday afternoon allowing a nice surge of warm, moist air throughout the forecast area. Surprisingly with better raob sampling at 12Z, there are still discrepancies among operational models, though the general trend is for a weaker system ejecting and lifting out further to the northwest (roughly a KMHK-KDSM-KMSN line). Still prefer a somewhat slower and further south timing and position per consistent ECMWF solutions given the jet streak remaining on the south and west side of the trough base. This should keep the majority, if not all of the cwa in the warm sector through most of the day, and have correspondingly went towards the warmer guidance numbers for high temps. Some locations could spike even warmer if more than a few peaks of sun are realized, and would not be surprised if some locations pushed above 60F. For the most part, warm sector rainfall and convection should remain relegated to the middle and lower Mississippi River valley Sunday evening, with weak frontogenesis/deformation trailing through central Kansas. Much of the local area will be dealing with the dryslot and downslope westerly component Sunday evening, only seeing meager wrap around moisture and precipitation potential with the wave lifting to the northwest. Have generally cut pops and qpf amounts given model trends, and would not expect much more than a dusting or few tenths of rain/snow mix over northwest and north central Missouri by Monday morning. Virtually no cold air exists behind this system for early next week, such that post frontal lows Monday morning will remain above average in a well mixed boundary layer. Dry weather can be expect Monday with the only real concern revolving around the potential of an elevated fire danger given dry westerly downslope sfc wind, lowering relative humidity values, and warmer than average temperatures. 21 Medium range (Tuesday through Saturday)... For the later half of the forecast, medium range models continue to show a fair amount of agreement on the large scale features for next week`s forecast. A quasi-zonal flow regime is advertised to persist across the continent as the flow across the eastern Pacific remains rather flat. This will continue to allow fast moving shortwaves to jet across the nation, with a few expected to periodically cutting-off over the Desert Southwest. This would indicate that temperatures should remain above average over the last half of the forecast as the majority of the cold air remains sequestered to our north, allowing afternoon highs to range from the 40s into the 50s, with overnight lows in the mid 20s to mid 30s. Looking closer at the forecast specifics, mid-range models of late have begun to settle on a solution which cuts-off a low across the Desert Southwest early in the coming work week as energy gets dumped from the Pacific jet into a 500mb weakness noted across northern Mexico. This is counter to other recent solutions which advertised a more progressive track for the shortwave energy, ultimately hinting at precipitation chances across Kansas and Missouri in the Tuesday to Wednesday time frame. However, with the growing consensus that the cutoff low will develop and eject through the southern Plains, the needed moisture and lift for any precipitation looks like it will pass to our south, thus have only kept a silent 20% POP in for Tuesday night. Cutter && .AVIATION... Very low confidence throughout the 18Z taf period as models are still struggling with mvfr cigs blanketing the area this morning; and have significant disagreement regarding return moisture surging north tomorrow morning. Have utilized a persistence forecast along with RUC 925 mb condensation pressure deficits in determining the longevity and areal extent of mvfr cigs this afternoon. Feel erosion will take longer than models indicate, but then become rapid as mixing within the cloud layer increases towards sunset. Have introduced a LLWS mention overnight as a sly LLJ strengthens with pressure falls to the west. Moisture should begin to surge north over cooler ground leading to lower cigs overspreading the terminals. Timing remains very uncertain and have trended towards a period after forecast soundings would suggest, but before most numerical guidance. Kept heights in the lower mvfr category, but could easily see heights come in the ifr or lifr category based on some forecast sounding data. 21 && .EAX WATCHES/WARNINGS/ADVISORIES... MO...NONE. KS...NONE. && $$ WFO EAX
AREA FORECAST DISCUSSION
NWS KANSAS CITY/PLEASANT HILL MO
1145 AM CST SAT JAN 21 2012 ...UPDATED AVIATION... .DISCUSSION... Early this morning, moisture trapped under a steep low level inversion in the form of stratus continues to advect southeast into the CWA. This stratus may prevent temperatures from falling into the single digits, but also poses a significant problem for high temperatures. The main forecast concerns are focused on precipitation chances on Sunday and Sunday night, and on temperatures throughout the upcoming week. For today: weak shortwave energy moving over Missouri this morning will quickly shift into the Ohio River valley today. Stratus is expected to hang around for a good portion of the day as low-level ridging axis does not slide through the area until early afternoon. Temperatures will remain in the 20s over northern Missouri with lower 30s possible in central Missouri and eastern Kansas. Tonight-Sunday: Our attention turns to a strong but very progressive upper trough moving over the Pacific coastline this morning. This upper trough is expected to pass through the region Sunday and end up in the Great Lakes by Monday. Ahead of the wave, northward theta-e advection will commence in earnest this evening with condensation pressure deficit plots indicating rapid stratus development. This stratus combined with increasing low-level warm advection should lead to a reversal of falling overnight temperatures with readings climbing after midnight. By 18z Sunday, surface troughing is expected to remain just west of the CWA. With pronounced meridional flow and an increasing surface pressure gradient, a very tricky temperature forecast will develop. Should stratus not be as thick as anticipated, or low- level cold advection develop later than currently forecast, temperatures could shoot well into 50s over a large chunk of the forecast area. Regarding the chance for precipitation, given the progressive nature of this wave and lack of downstream blocking there will not be enough time for deep moisture from the GOM to reach the area, with low level trajectories pushing higher quality moisture towards the lower Mississippi river valley. Thus, soundings reveal only minor saturation in the lowest levels which given isentropic lift and dynamic forcing aloft may be enough to produce light showers ahead of the surface front Sunday afternoon. On the backside of the upper wave there may be enough moisture to produce a fast moving band of mixed precipitation mainly over the northwestern and western grids before this system rotates into the Great Lakes Monday morning. Monday-Friday: Behind this system, little change in the overall weather pattern is anticipated with very progressive quasi-zonal flow continuing through the week. There remains little signal of any organized precipitation events in the local area. Temperatures will continue the trend of running above normal through the week. Dux && .AVIATION... Very low confidence throughout the 18Z taf period as models are still struggling with mvfr cigs blanketing the area this morning; and have significant disagreement regarding return moisture surging north tomorrow morning. Have utilized a persistence forecast along with RUC 925 mb condensation pressure deficits in determining the longevity and areal extent of mvfr cigs this afternoon. Feel erosion will take longer than models indicate, but then become rapid as mixing within the cloud layer increases towards sunset. Have introduced a LLWS mention overnight as a sly LLJ strengthens with pressure falls to the west. Moisture should begin to surge north over cooler ground leading to lower cigs overspreading the terminals. Timing remains very uncertain and have trended towards a period after forecast soundings would suggest, but before most numerical guidance. Kept heights in the lower mvfr category, but could easily see heights come in the ifr or lifr category based on some forecast sounding data. 21 && .EAX WATCHES/WARNINGS/ADVISORIES... MO...NONE. KS...NONE. && $$ WFO EAX
AREA FORECAST DISCUSSION
NWS NORTH PLATTE NE
249 PM CST SAT JAN 21 2012 .DISCUSSION... THE RUC CONTINUES TO INDICATE WIND ADVISORY CONDITIONS DEVELOPING ACROSS NCNTL NEB THIS AFTERNOON AS LOW PRESSURE DEEPENS ACROSS THE HIGH PLAINS. WIND SPEEDS SHOULD PEAK DURING THE LATE AFTERNOON AND THEN FALL OFF WITH THE LOSS OF DAYTIME HEATING. SOUTH WINDS CONTINUE OVERNIGHT AS A STRONG PACIFIC COLD FRONT APPROACHES THE PLAINS. THIS FRONT WILL SWEEP THROUGH THE FCST AREA SUNDAY MORNING AND LOW PRESSURE WILL CONSOLIDATE ACROSS THE MIDWEST. STRONG NORTHWEST WINDS WILL DEVELOP BEHIND THE SFC LOW ASSOCIATED WITH PACIFIC HIGH PRESSURE. A BLEND OF MAV AND MET GUIDANCE PRODUCED HIGH END WIND ADVISORY CONDITIONS. DEUEL COUNTY COULD PERHAPS REACH HIGH WIND CATEGORY BUT THAT IS LIKELY A RESULT OF WEIGHTING FACTORS ASSOCIATED WITH THE DATA FROM KSNY. THE NAM INDICATED GUSTS TO 55 MPH BUT ONLY ACROSS A SMALL PART OF CHERRY COUNTY. WINDS ARE EXPECTED TO STAY UP EAST OF HIGHWAY 83 SUNDAY EVENING FOR A FEW HOURS AS WRAP AROUND STRATUS PRODUCES A SHALLOW MIXED LAYER. WIND SPEEDS SHOULD DECLINE BETWEEN 03Z AND 06Z AS THE SFC LOW WILL PRESUMABLY BE FAR ENOUGH EAST FOR THE WINDS TO RELAX. ELSEWHERE WINDS SHOULD DROP OFF QUICKLY AS A CLEARING LINE MOVES EAST TO NEAR HIGHWAY 83 BY 00Z MONDAY. A BLEND OF ECMWF...GEM REGIONAL...NAM AND GFS WAS USED FOR QPF AMOUNTS WHICH ARE GENERALLY 1/10 OF INCH OR LESS. NOTE THE QPF IS POST FRONTAL AND THE PTYPE IS SNOW. WITH THE H700MB LOW TRACKING THROUGH THE NRN PLAINS...SNOW SHOWERS WOULD APPEAR TO BE THE DOMINANT STORM MODE BUT WE MAY BE DEALING WITH A MIXED MODE AT TIMES. THE NAM AND GFS ALSO KEEP THE FCST AREA MOSTLY DRY SO POPS ARE CHC CATEGORY. HPC FAVORED THE GEM MODEL AND THE UKMET. THE ECMWF APPEARED TO BE THE WETTER SOLN. THE GEM REGIONAL DEVELOPS A WEDGE OF WARP AROUND QPF ACROSS THE ERN ZONES AMOUNTING TO 1/3 OF AN INCH. GIVEN THE STRONG WINDS...SIGNIFICANT BLOWING SNOW WOULD DEVELOP IF THAT WERE TO VERIFY. HIGH PRESSURE SETTLES OVER THE FCST AREA MONDAY MORNING THROUGH TUESDAY. A SPLIT IN THE WESTERLIES DEVELOPS SENDING A LARGE UPPER LEVEL CUTOFF LOW THROUGH THE SRN PLAINS TUESDAY THROUGH FRIDAY. THIS SYSTEM WILL HAVE LITTLE OR NO EFFECT ON THE SENSIBLE WEATHER ACROSS THE FCST AREA EXCEPT TO HOLD PACIFIC HIGH PRESSURE IN PLACE. DEEP LOW PRESSURE CIRCULATING THROUGH CNTL AND SRN CANADA WILL ALSO DRAW PACIFIC HIGH PRESSURE THROUGH THE CNTL PLAINS WEDNESDAY AND THURSDAY BEFORE ANOTHER STRONG PACIFIC COLD FRONT DROPS THROUGH THURSDAY NIGHT OR FRIDAY. THE FCST IS DRY MONDAY THROUGH SUNDAY. THE GFS IS AMPLIFYING A DISTURBANCE THRU THE FCST AREA SATURDAY BUT IT APPEARS TO BE TOO FAST. THE ECMWF HOLDS THAT FEATURE OFFSHORE IN THE PACIFIC. && .AVIATION... WINDS WILL DECREASE TONIGHT AS THE PRESSURE GRADIENT EASES. THEN...A COLD FRONT WILL MOVE EAST ACROSS NEBRASKA TONIGHT...BRINGING A WIND SHIFT TO THE NORTHWEST BY 12Z AT BOTH KVTN AND KLBF. THE WIND SPEEDS WILL INCREASE THROUGH THE DAY...WITH GUSTS UPWARDS OF 35 TO 40KTS BY LATE MORNING AS COLD AIR ADVECTION AIDES IN STRONGER WINDS ALOFT BEING ABLE TO BE MIXED TO THE SURFACE. IN ADDITION...THERE DOES LOOK TO BE SOME PRECIPITATION BEHIND THE FRONT...WHICH MAY MOVE INTO THE KVTN TERMINAL IN THE MORNING HOURS. HAVE TRENDED THE FORECAST TO INCLUDE A CEILING DROPPING TO MVFR...ALONG WITH DECREASED VISIBILITIES DUE TO -SN IN THE LATE MORNING. TIMING MAY NEED TO BE ADJUSTED IN FOLLOWING FORECASTS. && .LBF WATCHES/WARNINGS/ADVISORIES...WIND ADVISORY FROM 6 AM CST /5 AM MST/ TO 6 PM CST /5 PM MST/ SUNDAY FOR NEZ004-005-022>025-035>037-056>059-069>071-094. WIND ADVISORY UNTIL 6 PM CST /5 PM MST/ THIS EVENING FOR NEZ005>010-094. WIND ADVISORY FROM 9 AM TO 9 PM CST SUNDAY FOR NEZ006>010- 026>029-038. && $$ SHORT TERM/EXTENDED...CDC AVIATION...BROOKS
AREA FORECAST DISCUSSION
NWS NORTH PLATTE NE
1138 AM CST SAT JAN 21 2012 .AVIATION... /FOR THE 18Z TAF ISSUANCE/ THE NEXT 24 HOURS WILL BE BUSY FOR AVIATION CONCERNS. STRONG SOUTHERLY WINDS WILL BE OBSERVED THROUGH THE REMAINDER OF THE AFTERNOON AS A TIGHT PRESSURE GRADIENT HAS SET UP ACROSS THE AREA AHEAD OF A STATIONARY FRONT OVER THE EASTERN PARTS OF WYOMING AND COLORADO. WINDS AT 850MB AT THE MRRN1 PROFILER IN NORTHWEST CHERRY COUNTY WERE 50KTS AT 15Z...WITH LESSER SPEEDS GOING SOUTH. ASSUMING THERE WILL BE SOME MIXING THIS AFTERNOON...PLAN ON SUSTAINED WINDS RANGING FROM AROUND 20 KT IN SOUTHWEST NEBRASKA TO 28KTS IN NORTHERN NEBRASKA...WITH GUSTS OF 25 TO 35KTS. THE FRONT TO THE WEST WILL MOVE EAST ACROSS NEBRASKA TONIGHT...ALLEVIATING THE PRESSURE GRADIENT AND ALLOWING WINDS TO DECREASE A BIT OVERNIGHT. BEHIND THE FRONT...WINDS WILL SHIFT TO THE NORTHWEST AND INCREASE. THE WIND SHIFT SHOULD REACH BOTH KVTN AND KLBF BY 12Z...WITH AN INCREASING TREND THROUGH THE MORNING. BY LATE MORNING COULD SEE GUSTS UPWARDS OF 35 TO 40KTS AS COLD AIR ADVECTION AIDES IN STRONGER WINDS ALOFT BEING ABLE TO BE MIXED TO THE SURFACE. IN ADDITION...THERE DOES LOOK TO BE SOME PRECIPITATION BEHIND THE FRONT...WHICH MAY MOVE INTO THE KVTN TERMINAL IN THE MORNING HOURS. HAVE TRENDED THE FORECAST TO INCLUDE A CEILING DROPPING TO IFR...ALONG WITH DECREASED VISIBILITIES WITH -SN IN THE LATTER PARTS OF THE FORECAST PERIOD. TIMING MAY NEED TO BE ADJUSTED IN FOLLOWING FORECASTS. && .PREV DISCUSSION... /ISSUED 1043 AM CST SAT JAN 21 2012/ UPDATE... SFC WINDS ARE ON THE WAY UP THIS MORNING WITH LOW PRESSURE DEEPENING ACROSS THE HIGH PLAINS. MERRIMAN PROFILER SHOWING 50KT AT THE LOWEST GATE. THE RUC SHOWS THIS BANK OF STRONG WINDS SHIFTING EAST AND MIXING DOWN THIS AFTERNOON SO A WIND ADVISORY IS IN PLACE FROM WRN CHERRY EAST. KICR GUSTED TO 40KT AT 1546UTC AND THIS APPEARS TO BE A SIGN OF THINGS TO COME. PREV DISCUSSION... /ISSUED 400 AM CST SAT JAN 21 2012/ SYNOPSIS... ARCTIC 1026 MB HIGH PRESSURE CENTERED OVER MINNESOTA THIS MORNING...AND SLIDING SOUTHEAST. WINDS HAVE BECOME SOUTH TO SOUTHWEST OVER THE CWA...WITH TEMPS IN THE LOWER TEENS. SATELLITE SHOWING SOME LOW STRATUS OVER PARTS OF CENTRAL AND EASTERN NEBRASKA. WATER VAPOR IMAGERY SHOW SPLIT FLOW CONTINUING WITH WESTERN CONUS SYSTEM SPLITTING. DISCUSSION... WITH THE HIGH FINALLY MOVING TO THE SOUTHEAST...AND RETURN SOUTHERLY FLOW...SHOULD BE ABLE TO WARM MOST OF THE CWA UP TODAY. GUIDANCE IN GOOD AGREEMENT WITH 40S OVER WESTERN ZONES...30S EAST. HOWEVER WITH THE WARMER TEMPS WILL COME GUSTY WINDS. TIGHT PRESSURE GRADIENT...WITH 3 HR PRESSURE FALLS AROUND 6 MB. MOS AND RAW MODEL DATA KEEPS WINDS BELOW GUIDANCE...AND FORECAST FOLLOWS...HOWEVER WILL NEED TO MONITOR. HIGHEST WINDS AT 850 MB APPROACH 60 KTS OVER NORTH CENTRAL...HOWEVER DO NOT EXPECT TO FULL MIX WHERE THE STRONGEST WINDS ALOFT ARE. TONIGHT THE NEXT LOW PRESSURE SYSTEM WILL CROSS THE NORTHERN ROCKIES...AND PUSH ONTO THE PLAINS. LOWER LEVELS ON THE DRY SIDE INITIALLY AND WILL NEED TO SATURATE TOP DOWN. THIS WILL LIKELY LIMIT THE AMOUNT OF QPF TO REACH THE GROUND. MIXING WILL KEEP TEMPS UP AND HAVE KEEP A MIX OF PRECIP BEFORE 06Z. AFTER 00Z COLD FRONT SHOULD BE CROSS THE AREA...WITH A CHANGE OVER TO SNOW. LIFT IS FOCUSED MORE TO THE NORTH...WITH ONLY VERY LIGHT ACCUMULATIONS EXPECTED...AT BEST. WITH THE CLOUDS EXPECT LOWS TO REMAIN MILD...IN THE 20S. SUNDAY COLD FRONT SHOULD PUSH ACROSS THE AREA EARLY. STRONG NW WINDS DEVELOP BEHIND THE FRONT...ALONG WITH THE CONTINUE SLIGHT CHANCE FOR PRECIP. WET BULB EFFECT...PER MODEL SOUNDING ANALYSIS...SHOULD RESULT IN ANY PRECIP IN THE FORM AS SNOW...HOWEVER WITH TEMPS WELL INTO THE 30S...POSSIBLY 40 FOR SUNDAY...COULD BRIEFLY SEE A MIX. MORE OF A CONCERN IS THE STRONG WINDS. WIND ADVISORY IS PROBABLE...HOWEVER WITH THE CHANCE FOR PRECIP...WILL HOLD OFF ON ANY HEADLINE AS MAY NEED TO INCORPORATE LIGHT SNOW INTO THE HEADLINE. ACTIVE PATTERN FOR NEXT WEEK...HOWEVER LIMITED MOISTURE TO WORK WITH OVER THE CWA. SEVERAL WAVES TO PUSH ACROSS THE PLAINS...WITH A STRONG WAVE TO PUSH ACROSS THE SOUTHERN PLAINS MONDAY NIGHT THROUGH TUESDAY. ARCTIC AIR TO RETREAT NORTH WITH SEASONAL CONDITIONS EXPECTED THROUGH MUCH OF THE WEEK. HIGHS IN THE 40S WITH POSSIBLY 50S FOR THURSDAY AHEAD OF THE NEXT COLD FRONT. && .LBF WATCHES/WARNINGS/ADVISORIES...WIND ADVISORY UNTIL 6 PM CST /5 PM MST/ THIS EVENING FOR NEZ005>010-094. && $$ SHORT TERM/EXTENDED...99 AVIATION...99
AREA FORECAST DISCUSSION...UPDATED
NWS NORTH PLATTE NE
1043 AM CST SAT JAN 21 2012 .UPDATE... SFC WINDS ARE ON THE WAY UP THIS MORNING WITH LOW PRESSURE DEEPENING ACROSS THE HIGH PLAINS. MERRIMAN PROFILER SHOWING 50KT AT THE LOWEST GATE. THE RUC SHOWS THIS BANK OF STRONG WINDS SHIFTING EAST AND MIXING DOWN THIS AFTERNOON SO A WIND ADVISORY IS IN PLACE FROM WRN CHERRY EAST. KICR GUSTED TO 40KT AT 1546UTC AND THIS APPEARS TO BE A SIGN OF THINGS TO COME. && .PREV DISCUSSION... /ISSUED 549 AM CST SAT JAN 21 2012/ AVIATION... UNRESTRICTED CEILING AND VISIBILITY IS LIKELY IN CENTRAL AND WESTERN NEBRASKA THROUGH THE NIGHT TONIGHT AND INTO EARLY SUNDAY. AFTER ABOUT 15Z WIND OVER CENTRAL AND WESTERN NEBRASKA WILL INCREASE AND BECOME 170-200 AND WINDY. WIND SPEEDS IN THE NORTH WILL BE 18-21G27-31KT AND IN THE NORTH 16-18G24-28KT. LOOKING BEYOND 12Z SUNDAY...WIND IS LIKELY TO BE EVEN STRONGER AND OUT OF THE NORTH TO NORTHWEST OVER THE AREA LATE MORNING THROUGH EARLY AFTERNOON. PREV DISCUSSION... /ISSUED 400 AM CST SAT JAN 21 2012/ SYNOPSIS... ARCTIC 1026 MB HIGH PRESSURE CENTERED OVER MINNESOTA THIS MORNING...AND SLIDING SOUTHEAST. WINDS HAVE BECOME SOUTH TO SOUTHWEST OVER THE CWA...WITH TEMPS IN THE LOWER TEENS. SATELLITE SHOWING SOME LOW STRATUS OVER PARTS OF CENTRAL AND EASTERN NEBRASKA. WATER VAPOR IMAGERY SHOW SPLIT FLOW CONTINUING WITH WESTERN CONUS SYSTEM SPLITTING. DISCUSSION... WITH THE HIGH FINALLY MOVING TO THE SOUTHEAST...AND RETURN SOUTHERLY FLOW...SHOULD BE ABLE TO WARM MOST OF THE CWA UP TODAY. GUIDANCE IN GOOD AGREEMENT WITH 40S OVER WESTERN ZONES...30S EAST. HOWEVER WITH THE WARMER TEMPS WILL COME GUSTY WINDS. TIGHT PRESSURE GRADIENT...WITH 3 HR PRESSURE FALLS AROUND 6 MB. MOS AND RAW MODEL DATA KEEPS WINDS BELOW GUIDANCE...AND FORECAST FOLLOWS...HOWEVER WILL NEED TO MONITOR. HIGHEST WINDS AT 850 MB APPROACH 60 KTS OVER NORTH CENTRAL...HOWEVER DO NOT EXPECT TO FULL MIX WHERE THE STRONGEST WINDS ALOFT ARE. TONIGHT THE NEXT LOW PRESSURE SYSTEM WILL CROSS THE NORTHERN ROCKIES...AND PUSH ONTO THE PLAINS. LOWER LEVELS ON THE DRY SIDE INITIALLY AND WILL NEED TO SATURATE TOP DOWN. THIS WILL LIKELY LIMIT THE AMOUNT OF QPF TO REACH THE GROUND. MIXING WILL KEEP TEMPS UP AND HAVE KEEP A MIX OF PRECIP BEFORE 06Z. AFTER 00Z COLD FRONT SHOULD BE CROSS THE AREA...WITH A CHANGE OVER TO SNOW. LIFT IS FOCUSED MORE TO THE NORTH...WITH ONLY VERY LIGHT ACCUMULATIONS EXPECTED...AT BEST. WITH THE CLOUDS EXPECT LOWS TO REMAIN MILD...IN THE 20S. SUNDAY COLD FRONT SHOULD PUSH ACROSS THE AREA EARLY. STRONG NW WINDS DEVELOP BEHIND THE FRONT...ALONG WITH THE CONTINUE SLIGHT CHANCE FOR PRECIP. WET BULB EFFECT...PER MODEL SOUNDING ANALYSIS...SHOULD RESULT IN ANY PRECIP IN THE FORM AS SNOW...HOWEVER WITH TEMPS WELL INTO THE 30S...POSSIBLY 40 FOR SUNDAY...COULD BRIEFLY SEE A MIX. MORE OF A CONCERN IS THE STRONG WINDS. WIND ADVISORY IS PROBABLE...HOWEVER WITH THE CHANCE FOR PRECIP...WILL HOLD OFF ON ANY HEADLINE AS MAY NEED TO INCORPORATE LIGHT SNOW INTO THE HEADLINE. ACTIVE PATTERN FOR NEXT WEEK...HOWEVER LIMITED MOISTURE TO WORK WITH OVER THE CWA. SEVERAL WAVES TO PUSH ACROSS THE PLAINS...WITH A STRONG WAVE TO PUSH ACROSS THE SOUTHERN PLAINS MONDAY NIGHT THROUGH TUESDAY. ARCTIC AIR TO RETREAT NORTH WITH SEASONAL CONDITIONS EXPECTED THROUGH MUCH OF THE WEEK. HIGHS IN THE 40S WITH POSSIBLY 50S FOR THURSDAY AHEAD OF THE NEXT COLD FRONT. && .LBF WATCHES/WARNINGS/ADVISORIES...WIND ADVISORY UNTIL 6 PM CST /5 PM MST/ THIS EVENING FOR NEZ005>010-094. && $$ SHORT TERM/EXTENDED...CDC AVIATION...BROOKS
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
310 PM EST SAT JAN 21 2012 .SYNOPSIS... A COLD FRONT WILL APPROACH FROM THE WEST TODAY AND WILL MOVE ACROSS THE COASTAL CAROLINAS LATE TONIGHT. COOL AND MOIST CONDITIONS WILL PREVAIL ON SUNDAY AS HIGH PRESSURE BUILDS FROM THE NORTH. ANOTHER COLD FRONT IS EXPECTED TO CROSS THE REGION MONDAY NIGHT. HIGH PRESSURE WILL FOLLOW TUESDAY INTO MID WEEK...WITH ANOTHER FRONTAL SYSTEM APPROACHING FROM THE WEST LATE NEXT WEEK. && .NEAR TERM /THROUGH TONIGHT/... AS OF 300 PM SATURDAY...POTENT SHORTWAVE CLEARLY EVIDENT ON WV IMAGERY PUSHING ACROSS NORTH GEORGIA ATTM WILL PIVOT THROUGH THE AREA TONIGHT. ADDITIONALLY...COLD FRONT MOVING EAST THROUGH UPSTATE SC WILL BECOME MORE E-W ORIENTED AND DROP SOUTHWARD OVERNIGHT. THESE TWO WILL WORK TOGETHER TO CONTINUE THUNDERSTORMS THROUGH TONIGHT. LATEST REGIONAL MOSAIC SHOWS A LINE OF STRONGER THUNDERSTORMS FROM APPROXIMATELY COLUMBIA, SC SOUTHWEST TO MACON, GA. THE STRONGEST STORMS ARE COLLOCATED WITH ENHANCED LIFT FROM THE PUNCH OF THE S/W TROUGH...AND EXPECT THE DEEPEST CONVECTION WILL PERSIST IN THIS MANNER. ALTHOUGH THE SHORTWAVE IS PROGGED TO WEAKEN AS IT MOVES NORTHEAST TONIGHT...IT APPEARS TO BE SLIGHTLY STRONGER THAN GUIDANCE HAD SUGGESTED WHICH MAY PERMIT CONVECTION TO CONTINUE LONGER. LATEST RUC AND HRRR ENSEMBLE REFLECTIVITY HAVE A GOOD HANDLE ON ONGOING SITUATION...SO HAVE USED A BLEND OF THESE FOR TIMING OF CONVECTION. VERY LITTLE INSTABILITY...LI`S GREATER THAN 0...AND WINDS ON THE LTX VWP OF ONLY 30 KTS AT 2 KFT ALL PROMOTE THE CONTINUED IDEA OF ONLY LIMITED SEVERE POTENTIAL DURING THE NEXT SEVERAL HOURS...EVEN THOUGH THE SOUTHERN HALF OF THE CWA REMAINS IN A SLIGHT RISK. STILL...FORECAST GUIDANCE DEVELOPS SOME 7 C/KM ML LAPSE RATES...LI`S TO -2...AND 0-6 KM SHEAR SUPPORTIVE OF MULTICELL STRUCTURES. HAVE KEPT SCT TSTMS IN WX GRIDS WITH CATEGORICAL POP FROM WEST TO EAST THROUGH 10 PM. CANNOT RULE OUT ONE OR TWO WARNINGS TONIGHT...BUT EXPECT PRIMARILY SUB-SEVERE WIND AND ISOLATED SMALL HAIL. FROPA OCCURS OVERNIGHT...AND HAVE ADJUSTED MIN TEMPS DOWNWARD A FEW DEGREES TO ACCOUNT FOR SLIGHTLY FASTER PROGRESSION. WINDS WILL TURN TO THE NORTH AT LBT BY 10PM...WILMINGTON AROUND MIDNIGHT...AND GEORGETOWN BY MORNING. VERY LITTLE DRYING BEHIND THE FRONT DUE TO MOISTURE BECOMING TRAPPED BENEATH THE FRONTAL INVERSION...SO VERY LIGHT RAIN SHOWERS AND DRIZZLE WILL PERSIST THROUGH MORNING. MINS TONIGHT WILL RANGE FROM THE LOWER 40S ACROSS THE EXTREME NORTH...TO AROUND 50 IN THE FAR SOUTH. && .SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/... AS OF 2:30 PM SATURDAY...COOL...CLOUDY AND MOIST DAY IN STORE FOR SUNDAY AS A SHORT-LIVED COLD AIR DAMMING SITUATION SETS UP. STEADY NE FLOW AT THE SURFACE AND EXTENSIVE CLOUD COVER WILL KEEP AFTERNOON TEMPERATURES A DEGREE OR SO EITHER SIDE OF 50 MOST LOCATIONS. AS IS TYPICAL FOR THIS TYPE OF PATTERN...EXPECT PATCHY DRIZZLE OR LIGHT RAIN TO MAKE APPEARANCES AT TIMES...WITH MINIMAL QPF DUE TO WEAK FORCING AND SHALLOW NATURE OF MOISTURE. THERE WILL BE A LIMITED DIURNAL RANGE OF TEMPERATURES...WITH LOWS MAINLY IN THE 40S OVERNIGHT. WEDGE PATTERN WILL ERODE EARLY ON MONDAY AS A COLD FRONT AND ASSOCIATED UPPER TROUGH APPROACH FROM THE WEST. FLOW WILL TURN TO THE SOUTH AND THEN SW MONDAY AFTERNOON...ALLOWING FOR A BIG WARM UP FROM THE PREVIOUS DAY. EXPECT HIGHS IN THE UPPER 60S TO AROUND 70...ABOUT 20 DEGREES HIGHER THAN ON SUNDAY. FRONT WILL MOVE ACROSS THE EASTERN CAROLINAS MONDAY EVENING AND OVERNIGHT AND WILL BE OFFSHORE BY AROUND DAYBREAK ON TUESDAY. MOISTURE WILL BE LIMITED WITH THIS SYSTEM AND BEST UPPER SUPPORT WILL PASS WELL TO THE NORTH...SO EXPECT ONLY ISOLATED TO SCATTERED CONVECTION TO ACCOMPANY FROPA. NOT MUCH IN THE WAY OF COLD ADVECTION WITH THIS FRONT...SO EXPECT LOWS WILL RANGE FROM THE MID 40S INLAND TO AROUND 50 AT THE COAST. && .LONG TERM /TUESDAY THROUGH SATURDAY/... AS OF 2:30 PM SATURDAY...MAIN FEATURE FOR THE EXTENDED CONTINUES TO BE THE CUTOFF MEANDERING ABOUT THE SOUTHWEST AND WHEN IT GETS KICKED OUT. THE LATEST OPERATIONAL RUN OF THE GFS HAS TRENDED MUCH SLOWER WHILE PREVIOUS RUNS MAINTAINED MORE OF A ZONAL FLOW. HPC CONTINUES TO FAVOR THE ECMWF SUITE OF PRODUCTS BASED ON MORE CONSISTENCY. THESE ARE A BIT SLOWER WITH THE SYSTEM BUT OVERALL ARE SIMILAR TO THIS TIME YESTERDAY. THE ONLY FORECAST CHANGES WITH THIS PACKAGE WERE TO DELAY THE POPS SLIGHTLY MAINTAINING THE SAME STRATEGY AS YESTERDAY WITH INCREASING VALUES FROM LATE THURSDAY THROUGH THE NEW DAY SATURDAY. ONLY MINOR TWEAKS TO TEMPERATURES WITH A SLIGHT INCREASE ACROSS THE BOARD TO MATCH HPC NUMBERS AND ADJACENT OFFICES. && .AVIATION /19Z SATURDAY THROUGH THURSDAY/... AS OF 18Z...SHOWERS HAVE INCREASED MORE RAPIDLY AND ARE ENCOMPASSING A WIDER AREA THAN EARLIER THOUGHT. BROKEN TO OVERCAST CLOUD VFR CLOUD COVER WILL PERSIST THROUGH THE AFTERNOON...BUT TEMPO MVFR VISIBILITIES WILL BE LIKELY WITH THE SHOWERS. SOUTH-SOUTHWEST TO SOUTHWEST WINDS WITH GUSTS TO 25-28 KNOTS ARE EXPECTED TO CONTINUE AHEAD OF THE APPROACHING COLD FRONT. HAVE NOT OBSERVED MUCH IN THE WAY OF SEA FOG...AND CURRENT FORECAST SURFACE WIND TRAJECTORIES...DEWPOINTS IN THE MID 50S AND WATER TEMPERATURES IN THE LOW 50S...SUGGEST IF ANY SEA FOG DOES DEVELOP IT WILL BE LIGHT AND REMAIN EAST OF THE CRE/MYR TERMINALS. SHOWERS AND ISOLATED THUNDERSTORMS WILL BECOME LIKELY LATE THIS AFTERNOON AT FLO/LBT SPREADING TO THE COASTAL TERMINALS THIS EVENING. PREDOMINATE MVFR CONDITIONS WILL BECOME LIKELY...WITH TEMPO IFR IN THE HEAVIEST SHOWERS. SINCE THUNDERSTORMS WILL BE ISOLATED WILL NOT INCLUDE IN TAFS AND WILL AMEND LATER IF NECESSARY. HIGH CONFIDENCE IN POST-FRONTAL IFR CEILINGS AND VISIBILITIES MID TO LATE EVENING...EXCEPT SHORTLY AFTER MIDNIGHT AT MYR/CRE. CONFIDENCE ID MODERATE THAT FLIGHT CONDITIONS WILL IMPROVE TO MVFR AT FLO/LBT AFTER MIDNIGHT...AND AND SOMEWHAT LOWER CONFIDENCE OF IMPROVED CONDITIONS AFTER SUNRISE AT THE COASTAL TERMINALS. EXTENDED OUTLOOK...POTENTIAL FOR IFR/LIFR CONDITIONS RE-DEVELOPING LATE SUNDAY PERSISTING INTO MONDAY MORNING. ANTICIPATE VFR TO DEVELOP MONDAY WITH EXPECTED TO CONTINUE THROUGH THE EXTENDED PERIOD. && .MARINE... NEAR TERM /THROUGH TONIGHT/... AS OF 300 PM SATURDAY...WINDS AND SEAS ARE FINALLY INCREASING SO SMALL CRAFT ADVISORY WILL CONTINUE THROUGH TONIGHT. SEAS HAVE ONLY REACHED 6 FT AT FRYING PAN SHOALS SO FAR TODAY...MOSTLY BECAUSE THE COLD SHELF WATERS HAVE INHIBITED THE STRONGEST WINDS FROM MIXING DOWN TO THE SURFACE. WINDS HAVE BUMPED TO 20 KTS AT 41110 LAST HOUR WITH SEAS APPROACHING 5 FT. SWAN AND WNAWAVE BOTH STILL EXPECTING 5-7 FT SEAS ACROSS AMZ250 AND AMZ252...WITH 4-6 FT IN THE SOUTHERN WATERS. WITH WIND INCREASE...FEEL THIS IS PRUDENT...AND WILL KEEP SCA AS IS. SMALL CRAFT CONDITIONS WILL IMPROVE RATHER QUICKLY TONIGHT...BECOMING ONLY AROUND 10 KTS AND VEERING TO THE NORTH THEN NORTHEAST BY SUNDAY MORNING. CONSEQUENTLY...SEAS FALL TO 3-4 FT...WITH A CONFUSED WAVE SPECTRUM DUE TO CHANGING WINDS. SCATTERED SHOWERS AND THUNDERSTORMS WILL CROSS THE WATERS LATE TONIGHT CREATING LOCALLY HIGHER WINDS AND SEAS. SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/... AS OF 2:30 PM SATURDAY...NELY FLOW OVER THE WATERS ON SUNDAY WILL TURN SWLY ON MONDAY AS A COLD FRONT APPROACHES FROM THE WEST. WINDS WILL RANGE FROM 15 TO 20 KTS EARLY ON SUNDAY BEFORE BECOMING LIGHT AND VEERING TO THE SE OVERNIGHT WITH THE APPROACH OF THE COLD FRONT. WINDS WILL PICK UP AGAIN MONDAY AFTERNOON BACK IN THE 15 TO 20 KT RANGE FROM THE SW. COLD FRONT MAY MOVE OFFSHORE BY AROUND DAYBREAK ON TUESDAY. SEAS WILL RANGE FROM 3 TO 5 FT FOR MUCH OF THE PERIOD. LONG TERM /TUESDAY THROUGH WEDNESDAY/... AS OF 2:30 PM SATURDAY...WESTERLY FLOW INITIALLY IN THE WAKE OF THE COLD FRONT. A SECONDARY PUSH OCCURS LATE TUESDAY INTO WEDNESDAY WHICH WILL TURN WINDS TO THE NORTHEAST. FINALLY RETURN FLOW SETS UP THURSDAY AS A SYSTEM TAKES SHAPE WELL TO THE SOUTHWEST. OVERALL WIND SPEEDS SHOULD REMAIN MODEST WITH THE POSSIBLE EXCEPTION OF LATE INT HE PERIOD WHEN THE SOUTHWEST FLOW SURGES. SEAS WILL REFLECT THE MODEST WINDS WITH AROUND TWO FEET FOR TUESDAY AND WEDNESDAY INCREASING SLIGHTLY THURSDAY. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...NONE. NC...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 5 PM EST THIS AFTERNOON FOR AMZ254- 256. SMALL CRAFT ADVISORY UNTIL 7 PM EST THIS EVENING FOR AMZ250- 252. && $$ NEAR TERM...JDW SHORT TERM...REK LONG TERM...SHK AVIATION...MRR MARINE...REK/JDW/SHK
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
238 PM EST SAT JAN 21 2012 .SYNOPSIS... A COLD FRONT WILL APPROACH FROM THE WEST TODAY AND WILL MOVE ACROSS THE COASTAL CAROLINAS LATE TONIGHT. COOL AND MOIST CONDITIONS WILL PREVAIL ON SUNDAY AS HIGH PRESSURE BUILDS FROM THE NORTH. ANOTHER COLD FRONT IS EXPECTED TO CROSS THE REGION MONDAY NIGHT. HIGH PRESSURE WILL FOLLOW TUESDAY INTO MID WEEK...WITH ANOTHER FRONTAL SYSTEM APPROACHING FROM THE WEST LATE NEXT WEEK. && .NEAR TERM /THROUGH TONIGHT/... AS OF 1230 PM SATURDAY...MINOR UPDATES TO INCREASE POP ACROSS THE AREA WHERE RAIN HAS OVERSPREAD MUCH OF THE CWA. HAVE ALSO TRENDED TEMPS DOWN SEVERAL DEGREES INLAND DUE TO RAIN-COOLING OF THE AIR MASS. HAVE ADJUSTED THE TEMP CURVE TO ATTEMPT TO ACCOUNT FOR RAINFALL AS IT HEADS EAST...WITH NO MORE HEATING EXPECTED TODAY. HAVE NOTICED A SLIGHT SLOWING OF PRECIP IN HRRR...AND WITH LATEST TORNADO WATCH (TOA 4) STILL 1 TIER OF COUNTIES WEST OF THE ILM CWA...STILL BELIEVE ONLY A LIMITED SEVERE THREAT WILL EXIST TODAY ACROSS WESTERN PORTIONS OF THE AREA. OTRW...PREVIOUS DISCUSSION BELOW: AS OF 1000 AM SATURDAY...CONCERN TODAY REVOLVES AROUND CONVECTION POTENTIAL AHEAD OF A COLD FRONT APPROACHING FROM THE WEST. COLD FRONT CURRENTLY ANALYZED TO BE JUST WEST OF THE MTNS AT THIS TIME IS ADVANCING EAST...WITH A BAND OF PREFRONTAL SHOWERS AND TSTMS PRECEDING IT. AHEAD OF THIS BOUNDARY...ILM CWA IS FIRMLY ENTRENCHED IN THE WARM SECTOR WITH DEEP SW FLOW THROUGH THE COLUMN. ALL LOCATIONS AWAY FROM THE BRUNSWICK COUNTY COAST WERE ALREADY IN THE 60S AS OF 10 AM. MAX TEMPS WILL BE TEMPERED BY SIGNIFICANT CLOUD COVER...BUT ENOUGH BREAKS WILL ALLOW MOST LOCATIONS TO RISE TO AROUND 70 TODAY. WITHIN THIS WARM SECTOR...WHERE CLOUDS ARE BREAKING ACROSS THE UPSTATE OF SC...NUMEROUS SHOWERS ARE DEVELOPING AND ADVECTING NORTHEAST INTO THIS AREA. HAVE BUMPED POP ACCORDINGLY TO ACCOUNT FOR THIS. MAIN IMPACTS STILL EXPECTED TO OCCUR LATE THIS AFTN AND THROUGH EARLY TONIGHT. SPC CONTINUED THE SLIGHT RISK IN THE SWODY1 FOR WESTERN PORTIONS...BASICALLY CKI-MAO-MEB AND WEST WITH WIND BEING THE PRIMARY THREAT. A FEW FACTORS WORKING AGAINST A WIDESPREAD SEVERE EVENT TODAY HOWEVER...NAMELY LACK OF PARAMETERS WORKING IN CONCERT. ALTHOUGH SBCAPE WILL JUMP TO 300-500 J/KG OVER INLAND ZONES (CONTAINED WITHIN THE SLIGHT RISK)...OTHER PARAMETERS APPEAR LIMITING. 50 KTS AT 2 KFT ON LTX VWP IS ACTUALLY PROGGED TO WEAKEN SLIGHTLY...SO LLJ WILL ONLY PEAK IN THE 40-50 KT RANGE DURING CONVECTION. ALTHOUGH 0-6 KM SHEAR VECTOR WILL BE AROUND 40 KTS...FAVORING MULTI-CELLULAR STORM TYPE...AND ML LAPSE RATES IMPROVE ABOVE 7 C/KM...THESE ARE CONFINED MOSTLY TO EASTERN ZONES. 0-3 KM SRH SHOULD REACH 200-300 M2/S2...PRIMARILY CAUSED BY INCREASING UNIDIRECTIONAL FLOW WITH HEIGHT...BUT IS ENHANCED IN AREAS WITH LESSER INSTABILITY. SO...USING THE HRRR ENSEMBLE REFLECTIVITY AS A GUIDE...EXPECT SHOWERS TO PERSIST THROUGH THE EARLY AFTN...WITH PREFRONTAL LINE REACHING MARLBORO COUNTY BETWEEN 3P-4P...AND EXITING OFFSHORE AROUND 9P. HAVE REMOVED MENTION OF GUSTY WINDS FROM WX GRIDS AND EXPECT PRIMARILY A NON SEVERE EVENT. OF COURSE...CANNOT RULE OUT AN ISOLATED DAMAGING WIND GUST...ESPECIALLY WITHIN ANY BOWING SEGMENTS/STRUCTURES WITHIN THE LINE...BUT PRIMARY THREATS WILL BE SUB-SEVERE WIND AND SMALL HAIL. WILL OF COURSE MONITOR...IF MORE SUNSHINE BREAKS OUT THAN ANTICIPATED...THIS COULD ENHANCE THE SEVERE THREAT THIS EVE. COLD FRONT DROPS NORTH TO SOUTH TONIGHT AND SHOULD BE PUSHING THROUGH THE SOUTHERN PORTIONS OF THE CWA BY 7AM SUNDAY. WEDGING HIGH PRESSURE BEHIND THIS FRONT TRAPS RESIDUAL MOISTURE ON DECREASING N/NE WINDS...SO SHOWERS/DRIZZLE WILL PERSIST THROUGH THE NIGHT. MINS TONIGHT WILL DROP INTO THE MID 40S ACROSS THE EXTREME NORTH...TO AROUND 50 IN THE SOUTHEAST. && .SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/... AS OF 2:30 PM SATURDAY...COOL...CLOUDY AND MOIST DAY IN STORE FOR SUNDAY AS A SHORT-LIVED COLD AIR DAMMING SITUATION SETS UP. STEADY NE FLOW AT THE SURFACE AND EXTENSIVE CLOUD COVER WILL KEEP AFTERNOON TEMPERATURES A DEGREE OR SO EITHER SIDE OF 50 MOST LOCATIONS. AS IS TYPICAL FOR THIS TYPE OF PATTERN...EXPECT PATCHY DRIZZLE OR LIGHT RAIN TO MAKE APPEARANCES AT TIMES...WITH MINIMAL QPF DUE TO WEAK FORCING AND SHALLOW NATURE OF MOISTURE. THERE WILL BE A LIMITED DIURNAL RANGE OF TEMPERATURES...WITH LOWS MAINLY IN THE 40S OVERNIGHT. WEDGE PATTERN WILL ERODE EARLY ON MONDAY AS A COLD FRONT AND ASSOCIATED UPPER TROUGH APPROACH FROM THE WEST. FLOW WILL TURN TO THE SOUTH AND THEN SW MONDAY AFTERNOON...ALLOWING FOR A BIG WARM UP FROM THE PREVIOUS DAY. EXPECT HIGHS IN THE UPPER 60S TO AROUND 70...ABOUT 20 DEGREES HIGHER THAN ON SUNDAY. FRONT WILL MOVE ACROSS THE EASTERN CAROLINAS MONDAY EVENING AND OVERNIGHT AND WILL BE OFFSHORE BY AROUND DAYBREAK ON TUESDAY. MOISTURE WILL BE LIMITED WITH THIS SYSTEM AND BEST UPPER SUPPORT WILL PASS WELL TO THE NORTH...SO EXPECT ONLY ISOLATED TO SCATTERED CONVECTION TO ACCOMPANY FROPA. NOT MUCH IN THE WAY OF COLD ADVECTION WITH THIS FRONT...SO EXPECT LOWS WILL RANGE FROM THE MID 40S INLAND TO AROUND 50 AT THE COAST. && .LONG TERM /TUESDAY THROUGH SATURDAY/... AS OF 2:30 PM SATURDAY...MAIN FEATURE FOR THE EXTENDED CONTINUES TO BE THE CUTOFF MEANDERING ABOUT THE SOUTHWEST AND WHEN IT GETS KICKED OUT. THE LATEST OPERATIONAL RUN OF THE GFS HAS TRENDED MUCH SLOWER WHILE PREVIOUS RUNS MAINTAINED MORE OF A ZONAL FLOW. HPC CONTINUES TO FAVOR THE ECMWF SUITE OF PRODUCTS BASED ON MORE CONSISTENCY. THESE ARE A BIT SLOWER WITH THE SYSTEM BUT OVERALL ARE SIMILAR TO THIS TIME YESTERDAY. THE ONLY FORECAST CHANGES WITH THIS PACKAGE WERE TO DELAY THE POPS SLIGHTLY MAINTAINING THE SAME STRATEGY AS YESTERDAY WITH INCREASING VALUES FROM LATE THURSDAY THROUGH THE NEW DAY SATURDAY. ONLY MINOR TWEAKS TO TEMPERATURES WITH A SLIGHT INCREASE ACROSS THE BOARD TO MATCH HPC NUMBERS AND ADJACENT OFFICES. && .AVIATION /19Z SATURDAY THROUGH THURSDAY/... AS OF 18Z...SHOWERS HAVE INCREASED MORE RAPIDLY AND ARE ENCOMPASSING A WIDER AREA THAN EARLIER THOUGHT. BROKEN TO OVERCAST CLOUD VFR CLOUD COVER WILL PERSIST THROUGH THE AFTERNOON...BUT TEMPO MVFR VISIBILITIES WILL BE LIKELY WITH THE SHOWERS. SOUTH-SOUTHWEST TO SOUTHWEST WINDS WITH GUSTS TO 25-28 KNOTS ARE EXPECTED TO CONTINUE AHEAD OF THE APPROACHING COLD FRONT. HAVE NOT OBSERVED MUCH IN THE WAY OF SEA FOG...AND CURRENT FORECAST SURFACE WIND TRAJECTORIES...DEWPOINTS IN THE MID 50S AND WATER TEMPERATURES IN THE LOW 50S...SUGGEST IF ANY SEA FOG DOES DEVELOP IT WILL BE LIGHT AND REMAIN EAST OF THE CRE/MYR TERMINALS. SHOWERS AND ISOLATED THUNDERSTORMS WILL BECOME LIKELY LATE THIS AFTERNOON AT FLO/LBT SPREADING TO THE COASTAL TERMINALS THIS EVENING. PREDOMINATE MVFR CONDITIONS WILL BECOME LIKELY...WITH TEMPO IFR IN THE HEAVIEST SHOWERS. SINCE THUNDERSTORMS WILL BE ISOLATED WILL NOT INCLUDE IN TAFS AND WILL AMEND LATER IF NECESSARY. HIGH CONFIDENCE IN POST-FRONTAL IFR CEILINGS AND VISIBILITIES MID TO LATE EVENING...EXCEPT SHORTLY AFTER MIDNIGHT AT MYR/CRE. CONFIDENCE ID MODERATE THAT FLIGHT CONDITIONS WILL IMPROVE TO MVFR AT FLO/LBT AFTER MIDNIGHT...AND AND SOMEWHAT LOWER CONFIDENCE OF IMPROVED CONDITIONS AFTER SUNRISE AT THE COASTAL TERMINALS. EXTENDED OUTLOOK...POTENTIAL FOR IFR/LIFR CONDITIONS RE-DEVELOPING LATE SUNDAY PERSISTING INTO MONDAY MORNING. ANTICIPATE VFR TO DEVELOP MONDAY WITH EXPECTED TO CONTINUE THROUGH THE EXTENDED PERIOD. && .MARINE... NEAR TERM /THROUGH TONIGHT/... AS OF 1230 PM SATURDAY...NO MAJOR CHANGES FOR THIS UPDATE. SEAS HAVE BEGUN TO INCREASE ACROSS THE SHELF WATERS WITH 41110 REPORTING 4.6 FT AT 12 PM. LATEST SWAN RUN KEEPS SCA SEAS BEYOND 00Z SO WILL CONSIDER EXTENDING SCA WITH THE 3PM PACKAGE. PREVIOUS DISCUSSION BELOW: AS OF 1000 AM SATURDAY...SMALL CRAFT ADVISORY IN EFFECT FOR ALL WATERS THROUGH TONIGHT. FORECAST REMAINS ON TRACK FOR SEA HEIGHTS...WITH 41013 REPORTING 7 FT AT 10 AM...WITH 4 FT AT 41110. WINDS HAVE BECOME QUITE GUSTY AT FRYING PAN SHOALS...BUT COLD SHELF WATERS ARE KEEPING WIND GUSTS DOWN IN THE INNER 20 NM. EXPECT GUSTS TO SLOWLY INCREASE...ESPECIALLY ACROSS AMZ250 AND AMZ252...HELPING TO FORCE WIND DRIVEN WAVES UP TO 6 FT BEFORE EASING TONIGHT. A FEW WAVES NEAR THE OUTER 20 NM RANGE WILL REACH 8 FT LATE THIS AFTN. SW WINDS OF 15-25 KTS WILL PERSIST THROUGH THE FRONTAL PASSAGE TONIGHT...WHEN THEY WILL TURN TO THE NORTH AND DECREASE TO LESS THAN 15 KTS. SEAS WILL FALL IN TANDEM...BECOMING 3-4 FT WITH A NORTHERLY CHOP BY THE END OF THE PERIOD. SCATTERED SHOWERS AND THUNDERSTORMS ARE EXPECTED TO CROSS THE WATERS LATE TONIGHT CREATING LOCALLY HIGHER WINDS AND SEAS. SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/... AS OF 2:30 PM SATURDAY...NELY FLOW OVER THE WATERS ON SUNDAY WILL TURN SWLY ON MONDAY AS A COLD FRONT APPROACHES FROM THE WEST. WINDS WILL RANGE FROM 15 TO 20 KTS EARLY ON SUNDAY BEFORE BECOMING LIGHT AND VEERING TO THE SE OVERNIGHT WITH THE APPROACH OF THE COLD FRONT. WINDS WILL PICK UP AGAIN MONDAY AFTERNOON BACK IN THE 15 TO 20 KT RANGE FROM THE SW. COLD FRONT MAY MOVE OFFSHORE BY AROUND DAYBREAK ON TUESDAY. SEAS WILL RANGE FROM 3 TO 5 FT FOR MUCH OF THE PERIOD. LONG TERM /TUESDAY THROUGH WEDNESDAY/... AS OF 2:30 PM SATURDAY...WESTERLY FLOW INITIALLY IN THE WAKE OF THE COLD FRONT. A SECONDARY PUSH OCCURS LATE TUESDAY INTO WEDNESDAY WHICH WILL TURN WINDS TO THE NORTHEAST. FINALLY RETURN FLOW SETS UP THURSDAY AS A SYSTEM TAKES SHAPE WELL TO THE SOUTHWEST. OVERALL WIND SPEEDS SHOULD REMAIN MODEST WITH THE POSSIBLE EXCEPTION OF LATE INT HE PERIOD WHEN THE SOUTHWEST FLOW SURGES. SEAS WILL REFLECT THE MODEST WINDS WITH AROUND TWO FEET FOR TUESDAY AND WEDNESDAY INCREASING SLIGHTLY THURSDAY. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...NONE. NC...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 5 PM EST THIS AFTERNOON FOR AMZ254- 256. SMALL CRAFT ADVISORY UNTIL 7 PM EST THIS EVENING FOR AMZ250- 252. && $$ NEAR TERM...JDW SHORT TERM...REK LONG TERM...SHK AVIATION...MRR MARINE...REK/JDW/SHK
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
1250 PM EST SAT JAN 21 2012 .SYNOPSIS... A COLD FRONT WILL APPROACH FROM THE WEST TODAY AND WILL MOVE ACROSS THE COASTAL CAROLINAS LATE TONIGHT. COOL AND MOIST CONDITIONS WILL PREVAIL ON SUNDAY AS HIGH PRESSURE BUILDS FROM THE NORTH. ANOTHER COLD FRONT IS EXPECTED TO CROSS THE REGION MONDAY NIGHT. HIGH PRESSURE WILL FOLLOW TUESDAY INTO MID WEEK...WITH ANOTHER FRONTAL SYSTEM APPROACHING FROM THE WEST LATE NEXT WEEK. && .NEAR TERM /THROUGH TONIGHT/... AS OF 1230 PM SATURDAY...MINOR UPDATES TO INCREASE POP ACROSS THE AREA WHERE RAIN HAS OVERSPREAD MUCH OF THE CWA. HAVE ALSO TRENDED TEMPS DOWN SEVERAL DEGREES INLAND DUE TO RAIN-COOLING OF THE AIR MASS. HAVE ADJUSTED THE TEMP CURVE TO ATTEMPT TO ACCOUNT FOR RAINFALL AS IT HEADS EAST...WITH NO MORE HEATING EXPECTED TODAY. HAVE NOTICED A SLIGHT SLOWING OF PRECIP IN HRRR...AND WITH LATEST TORNADO WATCH (TOA 4) STILL 1 TIER OF COUNTIES WEST OF THE ILM CWA...STILL BELIEVE ONLY A LIMITED SEVERE THREAT WILL EXIST TODAY ACROSS WESTERN PORTIONS OF THE AREA. OTRW...PREVIOUS DISCUSSION BELOW: AS OF 1000 AM SATURDAY...CONCERN TODAY REVOLVES AROUND CONVECTION POTENTIAL AHEAD OF A COLD FRONT APPROACHING FROM THE WEST. COLD FRONT CURRENTLY ANALYZED TO BE JUST WEST OF THE MTNS AT THIS TIME IS ADVANCING EAST...WITH A BAND OF PREFRONTAL SHOWERS AND TSTMS PRECEDING IT. AHEAD OF THIS BOUNDARY...ILM CWA IS FIRMLY ENTRENCHED IN THE WARM SECTOR WITH DEEP SW FLOW THROUGH THE COLUMN. ALL LOCATIONS AWAY FROM THE BRUNSWICK COUNTY COAST WERE ALREADY IN THE 60S AS OF 10 AM. MAX TEMPS WILL BE TEMPERED BY SIGNIFICANT CLOUD COVER...BUT ENOUGH BREAKS WILL ALLOW MOST LOCATIONS TO RISE TO AROUND 70 TODAY. WITHIN THIS WARM SECTOR...WHERE CLOUDS ARE BREAKING ACROSS THE UPSTATE OF SC...NUMEROUS SHOWERS ARE DEVELOPING AND ADVECTING NORTHEAST INTO THIS AREA. HAVE BUMPED POP ACCORDINGLY TO ACCOUNT FOR THIS. MAIN IMPACTS STILL EXPECTED TO OCCUR LATE THIS AFTN AND THROUGH EARLY TONIGHT. SPC CONTINUED THE SLIGHT RISK IN THE SWODY1 FOR WESTERN PORTIONS...BASICALLY CKI-MAO-MEB AND WEST WITH WIND BEING THE PRIMARY THREAT. A FEW FACTORS WORKING AGAINST A WIDESPREAD SEVERE EVENT TODAY HOWEVER...NAMELY LACK OF PARAMETERS WORKING IN CONCERT. ALTHOUGH SBCAPE WILL JUMP TO 300-500 J/KG OVER INLAND ZONES (CONTAINED WITHIN THE SLIGHT RISK)...OTHER PARAMETERS APPEAR LIMITING. 50 KTS AT 2 KFT ON LTX VWP IS ACTUALLY PROGGED TO WEAKEN SLIGHTLY...SO LLJ WILL ONLY PEAK IN THE 40-50 KT RANGE DURING CONVECTION. ALTHOUGH 0-6 KM SHEAR VECTOR WILL BE AROUND 40 KTS...FAVORING MULTI-CELLULAR STORM TYPE...AND ML LAPSE RATES IMPROVE ABOVE 7 C/KM...THESE ARE CONFINED MOSTLY TO EASTERN ZONES. 0-3 KM SRH SHOULD REACH 200-300 M2/S2...PRIMARILY CAUSED BY INCREASING UNIDIRECTIONAL FLOW WITH HEIGHT...BUT IS ENHANCED IN AREAS WITH LESSER INSTABILITY. SO...USING THE HRRR ENSEMBLE REFLECTIVITY AS A GUIDE...EXPECT SHOWERS TO PERSIST THROUGH THE EARLY AFTN...WITH PREFRONTAL LINE REACHING MARLBORO COUNTY BETWEEN 3P-4P...AND EXITING OFFSHORE AROUND 9P. HAVE REMOVED MENTION OF GUSTY WINDS FROM WX GRIDS AND EXPECT PRIMARILY A NON SEVERE EVENT. OF COURSE...CANNOT RULE OUT AN ISOLATED DAMAGING WIND GUST...ESPECIALLY WITHIN ANY BOWING SEGMENTS/STRUCTURES WITHIN THE LINE...BUT PRIMARY THREATS WILL BE SUB-SEVERE WIND AND SMALL HAIL. WILL OF COURSE MONITOR...IF MORE SUNSHINE BREAKS OUT THAN ANTICIPATED...THIS COULD ENHANCE THE SEVERE THREAT THIS EVE. COLD FRONT DROPS NORTH TO SOUTH TONIGHT AND SHOULD BE PUSHING THROUGH THE SOUTHERN PORTIONS OF THE CWA BY 7AM SUNDAY. WEDGING HIGH PRESSURE BEHIND THIS FRONT TRAPS RESIDUAL MOISTURE ON DECREASING N/NE WINDS...SO SHOWERS/DRIZZLE WILL PERSIST THROUGH THE NIGHT. MINS TONIGHT WILL DROP INTO THE MID 40S ACROSS THE EXTREME NORTH...TO AROUND 50 IN THE SOUTHEAST. && .SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/... AS OF 3 AM SATURDAY...HIGH PRESSURE WILL RIDGE DOWN INTO THE CAROLINAS ON SUNDAY FROM HIGH PRESSURE CENTERED OVER NORTHERN MAINE. LOOKS LIKE COLD AIR WILL WEDGE ITSELF DOWN THE LEE OF THE APPALACHIANS ON SUNDAY AS LINGERING TROUGH/FRONT WILL REMAIN SOUTH AND EAST OF LOCAL AREA. THIS SHALLOW COOL AIR WILL WORK ITS WAY IN WHILE SW FLOW ALOFT WILL ALLOW DRIER AND WARMER LAYER. OVERALL EXPECT THIS TO PRODUCE LOW CLOUDS AND DRIZZLE/LIGHT RAIN THROUGH SUNDAY. SHOULD BE AN INTERESTING TEMP FORECAST AS GFS KEEPS COLDER AIR WEDGED INLAND BUT SHOWS TEMPS CLOSER TO THE UPPER 50S ALONG THE COAST WHILE NAM SHOWS TEMPS CLOSER TO 50 TO ILM AND COASTAL AREAS FOR SUNDAY. FOR NOW...LOWERED MAX SLIGHTLY BUT WILL NOT JUMP TOTALLY ON NAM BANDWAGON JUST YET. WINDS COME BACK AROUND TO THE SOUTH AT THE SURFACE IN RETURN FLOW AHEAD OF NEXT SYSTEM APPROACHING ON SUNDAY NIGHT INTO MONDAY. A DEEPER SOUTHERLY FLOW WILL SET UP WITH A LLJ UP TO 40 KTS PUSHING MOISTURE BACK INTO AREA. PLENTY OF WAA WILL PRODUCE A RETURN TO WARMER TEMPS WITH HIGHS REACHING CLOSER TO 70 ON MONDAY. SHOULD SEE CLOUDS THROUGH THE PERIOD WITH FOG OVERNIGHT. LIGHT PCP ON SUNDAY WILL TAPER OFF BUT GREATER CHC OF RAIN SHOWERS WILL COME ON MONDAY AHEAD AND ALONG COLD FRONT. THE FRONT SHOULD MOVE THROUGH BY LATE MONDAY INTO EARLY TUESDAY. GFS SHOWS PLENTY OF DRY AIR MOVING IN BY DAYBREAK ON TUESDAY WITH PCP WATER VALUES DROPPING FROM NEAR 1.3 INCHES DOWN TO LESS THAN A HALF INCH BY TUES MORNING. && .LONG TERM /TUESDAY THROUGH FRIDAY/... AS OF 3 AM SATURDAY...SHOULD SEE A FAIRLY NICE START TO THE PERIOD WITH DEEP W-NW FLOW AND HIGH PRESSURE BUILDING IN BEHIND EXITING COLD FRONT. THIS WILL BE RELATIVELY SHORT LIVED AS PROGRESSIVE FLOW KEEPS THINGS MOVING ALONG. HIGH PRESSURE WILL SHIFT OFF SHORE AS NEXT SYSTEM MAKES ITS WAY EAST. SHOULD SEE SOME MID TO HIGH CLOUDS BACK IN THE FORECAST BY WEDNESDAY IN W-SW FLOW OVER THE TOP OF THE RIDGE ALOFT. WILL SEE SFC HIGH SHIFT OFF SHORE WITH RETURN FLOW SETTING UP ONCE AGAIN AS COLD FRONT PUSHES IN FROM THE N-NW. THIS FRONT WILL PRODUCE ANOTHER DAY OF CLOUDS AND PCP FOR THURS INTO FRI WITH POTENTIAL FOR ANOTHER LOW PRESSURE SYSTEM MOVING IN FROM THE GULF COAST BY THE WEEKEND. AS FOR TEMPS...EXPECT TO SEE A GREATER DIURNAL SWING IN A DRIER AIR MASS INITIALLY. TEMPS WILL BE INTO THE 60S DURING THE DAY BUT TUES NIGHT AND WED NIGHT WILL HAVE BETTER RADIATIONAL COOLING WITH LESS IN THE WAY OF CLOUDS AND LOWER DEWPOINTS. THEREFORE OVERNIGHT LOWS SHOULD MAKE IT DOWN TO 40 OR BELOW. AS CLOUDS AND PCP RETURN THURS AND FRI TEMPS OVERNIGHT WILL REMAIN HIGHER WITH DAYTIME HIGHS CONTINUING TO PUSH INTO THE 60S. && .AVIATION /18Z SATURDAY THROUGH THURSDAY/... AS OF 18Z...SHOWERS HAVE INCREASED MORE RAPIDLY AND ARE ENCOMPASSING A WIDER AREA THAN EARLIER THOUGHT. BROKEN TO OVERCAST CLOUD VFR CLOUD COVER WILL PERSIST THROUGH THE AFTERNOON...BUT TEMPO MVFR VISIBILITIES WILL BE LIKELY WITH THE SHOWERS. SOUTH-SOUTHWEST TO SOUTHWEST WINDS WITH GUSTS TO 25-28 KNOTS ARE EXPECTED TO CONTINUE AHEAD OF THE APPROACHING COLD FRONT. HAVE NOT OBSERVED MUCH IN THE WAY OF SEA FOG...AND CURRENT FORECAST SURFACE WIND TRAJECTORIES...DEWPOINTS IN THE MID 50S AND WATER TEMPERATURES IN THE LOW 50S...SUGGEST IF ANY SEA FOG DOES DEVELOP IT WILL BE LIGHT AND REMAIN EAST OF THE CRE/MYR TERMINALS. SHOWERS AND ISOLATED THUNDERSTORMS WILL BECOME LIKELY LATE THIS AFTERNOON AT FLO/LBT SPREADING TO THE COASTAL TERMINALS THIS EVENING. PREDOMINATE MVFR CONDITIONS WILL BECOME LIKELY...WITH TEMPO IFR IN THE HEAVIEST SHOWERS. SINCE THUNDERSTORMS WILL BE ISOLATED WILL NOT INCLUDE IN TAFS AND WILL AMEND LATER IF NECESSARY. HIGH CONFIDENCE IN POST-FRONTAL IFR CEILINGS AND VISIBILITIES MID TO LATE EVENING...EXCEPT SHORTLY AFTER MIDNIGHT AT MYR/CRE. CONFIDENCE ID MODERATE THAT FLIGHT CONDITIONS WILL IMPROVE TO MVFR AT FLO/LBT AFTER MIDNIGHT...AND AND SOMEWHAT LOWER CONFIDENCE OF IMPROVED CONDITIONS AFTER SUNRISE AT THE COASTAL TERMINALS. EXTENDED OUTLOOK...POTENTIAL FOR IFR/LIFR CONDITIONS RE-DEVELOPING LATE SUNDAY PERSISTING INTO MONDAY MORNING. ANTICIPATE VFR TO DEVELOP MONDAY WITH EXPECTED TO CONTINUE THROUGH THE EXTENDED PERIOD. && .MARINE... NEAR TERM /THROUGH TONIGHT/... AS OF 1230 PM SATURDAY...NO MAJOR CHANGES FOR THIS UPDATE. SEAS HAVE BEGUN TO INCREASE ACROSS THE SHELF WATERS WITH 41110 REPORTING 4.6 FT AT 12 PM. LATEST SWAN RUN KEEPS SCA SEAS BEYOND 00Z SO WILL CONSIDER EXTENDING SCA WITH THE 3PM PACKAGE. PREVIOUS DISCUSSION BELOW: AS OF 1000 AM SATURDAY...SMALL CRAFT ADVISORY IN EFFECT FOR ALL WATERS THROUGH TONIGHT. FORECAST REMAINS ON TRACK FOR SEA HEIGHTS...WITH 41013 REPORTING 7 FT AT 10 AM...WITH 4 FT AT 41110. WINDS HAVE BECOME QUITE GUSTY AT FRYING PAN SHOALS...BUT COLD SHELF WATERS ARE KEEPING WIND GUSTS DOWN IN THE INNER 20 NM. EXPECT GUSTS TO SLOWLY INCREASE...ESPECIALLY ACROSS AMZ250 AND AMZ252...HELPING TO FORCE WIND DRIVEN WAVES UP TO 6 FT BEFORE EASING TONIGHT. A FEW WAVES NEAR THE OUTER 20 NM RANGE WILL REACH 8 FT LATE THIS AFTN. SW WINDS OF 15-25 KTS WILL PERSIST THROUGH THE FRONTAL PASSAGE TONIGHT...WHEN THEY WILL TURN TO THE NORTH AND DECREASE TO LESS THAN 15 KTS. SEAS WILL FALL IN TANDEM...BECOMING 3-4 FT WITH A NORTHERLY CHOP BY THE END OF THE PERIOD. SCATTERED SHOWERS AND THUNDERSTORMS ARE EXPECTED TO CROSS THE WATERS LATE TONIGHT CREATING LOCALLY HIGHER WINDS AND SEAS. SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/... AS OF 3 AM SATURDAY...COOL BUT LIGHTER NORTHERLY FLOW WILL SET UP OVER THE COASTAL WATERS ON SUNDAY AS COLD FRONT REMAINS JUST SOUTH AND EAST. THIS WILL ALLOW SEAS TO RELAX DOWN LESS THAN 4 FT WITH WINDS 15 KTS OR LESS. AS FLOW CONTINUES TO REMAIN PROGRESSIVE...AN INCREASING RETURN FLOW WILL SET UP ONCE AGAIN LATE SUN NIGHT INTO MON WITH WINDS INCREASING UP TO 20 KTS. THIS WILL PUSH SEAS UP AGAIN INTO THE 3 TO 5 FT RANGE AND MAY SEE A BRIEF PERIOD OF 4 TO 6 FT SEAS BORDERING SCA THRESHOLDS MON AFTERNOON AS COLD FRONT APPROACHES. EXPECT COLD FRONT TO MOVE THROUGH BY END OF PERIOD WITH DECREASING OFF SHORE FLOW SETTING UP BY TUES MORNING AND SEAS DIMINISHING. LONG TERM /TUESDAY THROUGH WEDNESDAY/... AS OF 3 AM SATURDAY...AS MENTIONED PREVIOUSLY THE MARINE COMMUNITY WILL CONTINUE TO EXPERIENCE CHANGEABLE CONDITIONS IN A PROGRESSIVE PATTERN. A MUCH LIGHTER FLOW DEVELOPS TUES INTO WED AS HIGH PRESSURE MOVES OVER THE WATERS WITH WINDS VEERING AROUND FROM NW TO NE. WITH WINDS REMAINING LESS THAN 10 KTS THROUGH MOST OF THE PERIOD...SEAS WILL DIMINISH DOWN FROM 2 TO 4 FT TUES MORNING DOWN TO LESS THAN 3 FT TUES NIGHT THROUGH WED NIGHT. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...NONE. NC...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 5 PM EST THIS AFTERNOON FOR AMZ254- 256. SMALL CRAFT ADVISORY UNTIL 7 PM EST THIS EVENING FOR AMZ250- 252. && $$ NEAR TERM...JDW SHORT TERM...RGZ LONG TERM...RGZ AVIATION...MRR
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
1219 PM EST SAT JAN 21 2012 .SYNOPSIS... A COLD FRONT WILL APPROACH FROM THE WEST TODAY AND WILL MOVE ACROSS THE COASTAL CAROLINAS LATE TONIGHT. COOL AND MOIST CONDITIONS WILL PREVAIL ON SUNDAY AS HIGH PRESSURE BUILDS FROM THE NORTH. ANOTHER COLD FRONT IS EXPECTED TO CROSS THE REGION MONDAY NIGHT. HIGH PRESSURE WILL FOLLOW TUESDAY INTO MID WEEK...WITH ANOTHER FRONTAL SYSTEM APPROACHING FROM THE WEST LATE NEXT WEEK. && .NEAR TERM /THROUGH TONIGHT/... AS OF 1000 AM SATURDAY...CONCERN TODAY REVOLVES AROUND CONVECTION POTENTIAL AHEAD OF A COLD FRONT APPROACHING FROM THE WEST. COLD FRONT CURRENTLY ANALYZED TO BE JUST WEST OF THE MTNS AT THIS TIME IS ADVANCING EAST...WITH A BAND OF PREFRONTAL SHOWERS AND TSTMS PRECEDING IT. AHEAD OF THIS BOUNDARY...ILM CWA IS FIRMLY ENTRENCHED IN THE WARM SECTOR WITH DEEP SW FLOW THROUGH THE COLUMN. ALL LOCATIONS AWAY FROM THE BRUNSWICK COUNTY COAST WERE ALREADY IN THE 60S AS OF 10 AM. MAX TEMPS WILL BE TEMPERED BY SIGNIFICANT CLOUD COVER...BUT ENOUGH BREAKS WILL ALLOW MOST LOCATIONS TO RISE TO AROUND 70 TODAY. WITHIN THIS WARM SECTOR...WHERE CLOUDS ARE BREAKING ACROSS THE UPSTATE OF SC...NUMEROUS SHOWERS ARE DEVELOPING AND ADVECTING NORTHEAST INTO THIS AREA. HAVE BUMPED POP ACCORDINGLY TO ACCOUNT FOR THIS. MAIN IMPACTS STILL EXPECTED TO OCCUR LATE THIS AFTN AND THROUGH EARLY TONIGHT. SPC CONTINUED THE SLIGHT RISK IN THE SWODY1 FOR WESTERN PORTIONS...BASICALLY CKI-MAO-MEB AND WEST WITH WIND BEING THE PRIMARY THREAT. A FEW FACTORS WORKING AGAINST A WIDESPREAD SEVERE EVENT TODAY HOWEVER...NAMELY LACK OF PARAMETERS WORKING IN CONCERT. ALTHOUGH SBCAPE WILL JUMP TO 300-500 J/KG OVER INLAND ZONES (CONTAINED WITHIN THE SLIGHT RISK)...OTHER PARAMETERS APPEAR LIMITING. 50 KTS AT 2 KFT ON LTX VWP IS ACTUALLY PROGGED TO WEAKEN SLIGHTLY...SO LLJ WILL ONLY PEAK IN THE 40-50 KT RANGE DURING CONVECTION. ALTHOUGH 0-6 KM SHEAR VECTOR WILL BE AROUND 40 KTS...FAVORING MULTI-CELLULAR STORM TYPE...AND ML LAPSE RATES IMPROVE ABOVE 7 C/KM...THESE ARE CONFINED MOSTLY TO EASTERN ZONES. 0-3 KM SRH SHOULD REACH 200-300 M2/S2...PRIMARILY CAUSED BY INCREASING UNIDIRECTIONAL FLOW WITH HEIGHT...BUT IS ENHANCED IN AREAS WITH LESSER INSTABILITY. SO...USING THE HRRR ENSEMBLE REFLECTIVITY AS A GUIDE...EXPECT SHOWERS TO PERSIST THROUGH THE EARLY AFTN...WITH PREFRONTAL LINE REACHING MARLBORO COUNTY BETWEEN 3P-4P...AND EXITING OFFSHORE AROUND 9P. HAVE REMOVED MENTION OF GUSTY WINDS FROM WX GRIDS AND EXPECT PRIMARILY A NON SEVERE EVENT. OF COURSE...CANNOT RULE OUT AN ISOLATED DAMAGING WIND GUST...ESPECIALLY WITHIN ANY BOWING SEGMENTS/STRUCTURES WITHIN THE LINE...BUT PRIMARY THREATS WILL BE SUB-SEVERE WIND AND SMALL HAIL. WILL OF COURSE MONITOR...IF MORE SUNSHINE BREAKS OUT THAN ANTICIPATED...THIS COULD ENHANCE THE SEVERE THREAT THIS EVE. COLD FRONT DROPS NORTH TO SOUTH TONIGHT AND SHOULD BE PUSHING THROUGH THE SOUTHERN PORTIONS OF THE CWA BY 7AM SUNDAY. WEDGING HIGH PRESSURE BEHIND THIS FRONT TRAPS RESIDUAL MOISTURE ON DECREASING N/NE WINDS...SO SHOWERS/DRIZZLE WILL PERSIST THROUGH THE NIGHT. MINS TONIGHT WILL DROP INTO THE MID 40S ACROSS THE EXTREME NORTH...TO AROUND 50 IN THE SOUTHEAST. && .SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/... AS OF 3 AM SATURDAY...HIGH PRESSURE WILL RIDGE DOWN INTO THE CAROLINAS ON SUNDAY FROM HIGH PRESSURE CENTERED OVER NORTHERN MAINE. LOOKS LIKE COLD AIR WILL WEDGE ITSELF DOWN THE LEE OF THE APPALACHIANS ON SUNDAY AS LINGERING TROUGH/FRONT WILL REMAIN SOUTH AND EAST OF LOCAL AREA. THIS SHALLOW COOL AIR WILL WORK ITS WAY IN WHILE SW FLOW ALOFT WILL ALLOW DRIER AND WARMER LAYER. OVERALL EXPECT THIS TO PRODUCE LOW CLOUDS AND DRIZZLE/LIGHT RAIN THROUGH SUNDAY. SHOULD BE AN INTERESTING TEMP FORECAST AS GFS KEEPS COLDER AIR WEDGED INLAND BUT SHOWS TEMPS CLOSER TO THE UPPER 50S ALONG THE COAST WHILE NAM SHOWS TEMPS CLOSER TO 50 TO ILM AND COASTAL AREAS FOR SUNDAY. FOR NOW...LOWERED MAX SLIGHTLY BUT WILL NOT JUMP TOTALLY ON NAM BANDWAGON JUST YET. WINDS COME BACK AROUND TO THE SOUTH AT THE SURFACE IN RETURN FLOW AHEAD OF NEXT SYSTEM APPROACHING ON SUNDAY NIGHT INTO MONDAY. A DEEPER SOUTHERLY FLOW WILL SET UP WITH A LLJ UP TO 40 KTS PUSHING MOISTURE BACK INTO AREA. PLENTY OF WAA WILL PRODUCE A RETURN TO WARMER TEMPS WITH HIGHS REACHING CLOSER TO 70 ON MONDAY. SHOULD SEE CLOUDS THROUGH THE PERIOD WITH FOG OVERNIGHT. LIGHT PCP ON SUNDAY WILL TAPER OFF BUT GREATER CHC OF RAIN SHOWERS WILL COME ON MONDAY AHEAD AND ALONG COLD FRONT. THE FRONT SHOULD MOVE THROUGH BY LATE MONDAY INTO EARLY TUESDAY. GFS SHOWS PLENTY OF DRY AIR MOVING IN BY DAYBREAK ON TUESDAY WITH PCP WATER VALUES DROPPING FROM NEAR 1.3 INCHES DOWN TO LESS THAN A HALF INCH BY TUES MORNING. && .LONG TERM /TUESDAY THROUGH FRIDAY/... AS OF 3 AM SATURDAY...SHOULD SEE A FAIRLY NICE START TO THE PERIOD WITH DEEP W-NW FLOW AND HIGH PRESSURE BUILDING IN BEHIND EXITING COLD FRONT. THIS WILL BE RELATIVELY SHORT LIVED AS PROGRESSIVE FLOW KEEPS THINGS MOVING ALONG. HIGH PRESSURE WILL SHIFT OFF SHORE AS NEXT SYSTEM MAKES ITS WAY EAST. SHOULD SEE SOME MID TO HIGH CLOUDS BACK IN THE FORECAST BY WEDNESDAY IN W-SW FLOW OVER THE TOP OF THE RIDGE ALOFT. WILL SEE SFC HIGH SHIFT OFF SHORE WITH RETURN FLOW SETTING UP ONCE AGAIN AS COLD FRONT PUSHES IN FROM THE N-NW. THIS FRONT WILL PRODUCE ANOTHER DAY OF CLOUDS AND PCP FOR THURS INTO FRI WITH POTENTIAL FOR ANOTHER LOW PRESSURE SYSTEM MOVING IN FROM THE GULF COAST BY THE WEEKEND. AS FOR TEMPS...EXPECT TO SEE A GREATER DIURNAL SWING IN A DRIER AIR MASS INITIALLY. TEMPS WILL BE INTO THE 60S DURING THE DAY BUT TUES NIGHT AND WED NIGHT WILL HAVE BETTER RADIATIONAL COOLING WITH LESS IN THE WAY OF CLOUDS AND LOWER DEWPOINTS. THEREFORE OVERNIGHT LOWS SHOULD MAKE IT DOWN TO 40 OR BELOW. AS CLOUDS AND PCP RETURN THURS AND FRI TEMPS OVERNIGHT WILL REMAIN HIGHER WITH DAYTIME HIGHS CONTINUING TO PUSH INTO THE 60S. && .AVIATION /18Z SATURDAY THROUGH THURSDAY/... AS OF 18Z...SHOWERS HAVE INCREASED MORE RAPIDLY AND ARE ENCOMPASSING A WIDER AREA THAN EARLIER THOUGHT. BROKEN TO OVERCAST CLOUD VFR CLOUD COVER WILL PERSIST THROUGH THE AFTERNOON...BUT TEMPO MVFR VISIBILITIES WILL BE LIKELY WITH THE SHOWERS. SOUTH-SOUTHWEST TO SOUTHWEST WINDS WITH GUSTS TO 25-28 KNOTS ARE EXPECTED TO CONTINUE AHEAD OF THE APPROACHING COLD FRONT. HAVE NOT OBSERVED MUCH IN THE WAY OF SEA FOG...AND CURRENT FORECAST SURFACE WIND TRAJECTORIES ...DEWPOINTS IN THE MID 50S AND WATER TEMPERATURES IN THE LOW 50S...SUGGEST IF ANY SEA FOG DOES DEVELOP IT WILL BE LIGHT AND REMAIN EAST OF THE CRE/MYR TERMINALS. SHOWERS AND ISOLATED THUNDERSTORMS WILL BECOME LIKELY LATE THIS AFTERNOON AT FLO/LBT SPREADING TO THE COASTAL TERMINALS THIS EVENING. PREDOMINATE MVFR CONDITIONS WILL BECOME LIKELY...WITH TEMPO IFR IN THE HEAVIEST SHOWERS. SINCE THUNDERSTORMS WILL BE ISOLATED WILL NOT INCLUDE IN TAFS AND WILL AMEND LATER IF NECESSARY. HIGH CONFIDENCE IN POST-FRONTAL IFR CEILINGS AND VISIBILITIES MID TO LATE EVENING...EXCEPT SHORTLY AFTER MIDNIGHT AT MYR/CRE. CONFIDENCE ID MODERATE THAT FLIGHT CONDITIONS WILL IMPROVE TO MVFR AT FLO/LBT AFTER MIDNIGHT...AND AND SOMEWHAT LOWER CONFIDENCE OF IMPROVED CONDITIONS AFTER SUNRISE AT THE COASTAL TERMINALS. EXTENDED OUTLOOK...POTENTIAL FOR IFR/LIFR CONDITIONS RE-DEVELOPING LATE SUNDAY PERSISTING INTO MONDAY MORNING. ANTICIPATE VFR TO DEVELOP MONDAY WITH EXPECTED TO CONTINUE THROUGH THE EXTENDED PERIOD. && .MARINE... NEAR TERM /THROUGH TONIGHT/... AS OF 1000 AM SATURDAY...SMALL CRAFT ADVISORY IN EFFECT FOR ALL WATERS THROUGH TONIGHT. FORECAST REMAINS ON TRACK FOR SEA HEIGHTS...WITH 41013 REPORTING 7 FT AT 10 AM...WITH 4 FT AT 41110. WINDS HAVE BECOME QUITE GUSTY AT FRYING PAN SHOALS...BUT COLD SHELF WATERS ARE KEEPING WIND GUSTS DOWN IN THE INNER 20 NM. EXPECT GUSTS TO SLOWLY INCREASE...ESPECIALLY ACROSS AMZ250 AND AMZ252...HELPING TO FORCE WIND DRIVEN WAVES UP TO 6 FT BEFORE EASING TONIGHT. A FEW WAVES NEAR THE OUTER 20 NM RANGE WILL REACH 8 FT LATE THIS AFTN. SW WINDS OF 15-25 KTS WILL PERSIST THROUGH THE FRONTAL PASSAGE TONIGHT...WHEN THEY WILL TURN TO THE NORTH AND DECREASE TO LESS THAN 15 KTS. SEAS WILL FALL IN TANDEM...BECOMING 3-4 FT WITH A NORTHERLY CHOP BY THE END OF THE PERIOD. SCATTERED SHOWERS AND THUNDERSTORMS ARE EXPECTED TO CROSS THE WATERS LATE TONIGHT CREATING LOCALLY HIGHER WINDS AND SEAS. SHORT TERM /SUNDAY THROUGH MONDAY NIGHT/... AS OF 3 AM SATURDAY...COOL BUT LIGHTER NORTHERLY FLOW WILL SET UP OVER THE COASTAL WATERS ON SUNDAY AS COLD FRONT REMAINS JUST SOUTH AND EAST. THIS WILL ALLOW SEAS TO RELAX DOWN LESS THAN 4 FT WITH WINDS 15 KTS OR LESS. AS FLOW CONTINUES TO REMAIN PROGRESSIVE...AN INCREASING RETURN FLOW WILL SET UP ONCE AGAIN LATE SUN NIGHT INTO MON WITH WINDS INCREASING UP TO 20 KTS. THIS WILL PUSH SEAS UP AGAIN INTO THE 3 TO 5 FT RANGE AND MAY SEE A BRIEF PERIOD OF 4 TO 6 FT SEAS BORDERING SCA THRESHOLDS MON AFTERNOON AS COLD FRONT APPROACHES. EXPECT COLD FRONT TO MOVE THROUGH BY END OF PERIOD WITH DECREASING OFF SHORE FLOW SETTING UP BY TUES MORNING AND SEAS DIMINISHING. LONG TERM /TUESDAY THROUGH WEDNESDAY/... AS OF 3 AM SATURDAY...AS MENTIONED PREVIOUSLY THE MARINE COMMUNITY WILL CONTINUE TO EXPERIENCE CHANGEABLE CONDITIONS IN A PROGRESSIVE PATTERN. A MUCH LIGHTER FLOW DEVELOPS TUES INTO WED AS HIGH PRESSURE MOVES OVER THE WATERS WITH WINDS VEERING AROUND FROM NW TO NE. WITH WINDS REMAINING LESS THAN 10 KTS THROUGH MOST OF THE PERIOD...SEAS WILL DIMINISH DOWN FROM 2 TO 4 FT TUES MORNING DOWN TO LESS THAN 3 FT TUES NIGHT THROUGH WED NIGHT. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...NONE. NC...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 5 PM EST THIS AFTERNOON FOR AMZ254- 256. SMALL CRAFT ADVISORY UNTIL 7 PM EST THIS EVENING FOR AMZ250- 252. && $$ NEAR TERM...JDW SHORT TERM...RGZ LONG TERM...RGZ AVIATION...MRR
AREA FORECAST DISCUSSION FOR SOUTHEAST SD/SOUTHWEST MN/NORTHWEST IA
NWS SIOUX FALLS SD
151 PM CST SAT JAN 21 2012 .DISCUSSION.../ISSUED AT 1100 AM CST/ NUMEROUS UPDATES TO THE FORECAST THIS MORNING. FIRST WAS UNEXPECTED AREA OF PRECIPITATION WHICH BLOSSOMED EARLY THIS MORNING ACROSS FAR EASTERN SOUTH DAKOTA...MUCH OF NORTHWEST IOWA...AND SOUTHWEST MINNESOTA. APPARANT SOURCE OF THE SUDDEN DEVELOPMENT OF SNOWFALL WAS SEEDER FEEDER AS BLOB OF MID LEVEL CLOUDS PUSHED ACROSS THE AREA. LOWER CLOUDS WERE LIMITED TO A VERY DENDRITIC DEPTH OF 1500 TO 2500 FT THICKNESS BASED ON RUC/NAM MOISTURE PROFILES AND OBSERVED CEILINGS. FURTHER SUPPORT IS THE AREA OF MID LEVEL RETURNS NORTH OF THE CWA WHICH ARE BASED AROUND 8000-9000 FEET. AS FAST AS PRECIPITATION DEVELOPED...THIS IS ALSO ENDING JUST AS QUICKLY AROUND THE IMMEDIATE KFSD AREA. HOWEVER..AM WATCHING A COUPLE OF CLOUD LAYERS ON SATELLITE MOVING DIFFERENT DIRECTION...WITH THE LAST AREA OF MID CLOUDS IN THE JAMES VALLEY SLIDING EASTWARD. MAY GET A LITTLE BACK EDGE RESURGENCE IN SNOWFALL AS THIS AREA OF MID CLOUDS GOES PAST...BUT GENERALLY HAVE COVERAGE OF PRECIP SHIFTING EAST AND OVERALL INTENSITY OF PRECIPITATION DROPPING OFF AS WELL. LOWER CLOUDS ARE HOPELESSLY TRAPPED BELOW THE INVERSION AND CLOUD BEARING WINDS ARE NOT SUPPORTIVE OF ANY AGGRESSIVE EASTWARD PUSH. THEREFORE...UNLESS THE MOISTURE IS PRECIPITATED OUT OF THE LAYER... LIKELY THAT THERE WILL BE QUITE A FEW LOW CLOUDS FOR QUITE A BIT LONGER. RAISED THE SKYCOVER CONSIDERABLY ALONG AND EAST OF INTERSTATE 29 THIS AFTERNOON...AND TO THE WEST HIGHER CLOUDS WILL BE EVENING THE PLAYING FIELD WITH TIME AS WELL. FINALLY...ISSUED A WIND ADVISORY FOR THE HIGHER ELEVATION LOCATIONS OF SOUTH CENTRAL SD FOR REST OF THIS MORNING AND AFTERNOON...WHERE A FEW WIND GUSTS OVER 45 MPH ARE MOST LIKELY. /CHAPMAN && .AVIATION.../FOR THE 18Z TAF ISSUANCE/ NUMEROUS AVIATION CONCERNS THIS GO AROUND. WIDESPREAD MVFR CEILINGS PERSIST ALONG AND EAST OF THE JAMES VALLEY. WITH MOISTURE TRAPPED BELOW A STRONG INVERSION AND A SOUTH/SOUTHEAST WIND ADVERTISED IN THE CLOUD BEARING LEVELS...EXPECT VERY LITTLE TO CHANGE OTHER THAN THE TYPICAL GRADUAL LOWERING OF CEILINGS AS INVERSION SHARPENS. WINDS WILL ALSO REMAIN STRONG WITH GUSTS OF 30 TO 35 KTS... ESPECIALLY WEST OF INTERSTATE 29...AND THESE WINDS WILL RESULT IN SOME AREAS OF BLOWING SNOW...BUT FAR FROM A WIDESPREAD RISK AS SOUTH GRADIENT IS A MORE STABLE AIRFLOW. ELEVATED LOCATIONS WOULD PROBABLY FARE THE WORST IN THIS SETUP... WHICH IS NOT WHERE TYPICAL AIRFIELDS LOCATED. A DISTURBANCE IS EXPECTED TO SPREAD NORTHEAST ACROSS THE BETTER LOWER TO MID LEVEL BOUNDARY LATER TONIGHT THROUGH SUNDAY MORNING ACROSS CENTRAL SOUTH DAKOTA...SO LARGEST IMPACT FOR PRECIPITATION DEVELOPMENT WILL LIKELY BE FOR KHON/KMHE AREAS... PERHAPS REACHING AS FAR EAST AS INTERSTATE 29 AREA AFTER 16Z. THERE IS A LOW CHANCE OF FREEZING RAIN IN HURON AFTER 10Z AS INITIAL PV ADVECTION OCCURS...BUT THE PROBABILITY IS LOW ENOUGH THAT DID NOT INCLUDE IN TAF AT THIS TIME. HOWEVER...DID MENTION RISK OF FREEZING RAIN OR SLEET BY MID MORNING...BUT SHOULD BE A FAIRLY NARROW WINDOW WITH CHANGEOVER TO SNOW THROUGH COOLING OF ATMOSPHERE BY 17Z AT KHON. /CHAPMAN && .PREV DISCUSSION.../ISSUED AT 1030 AM CST/ MAIN CONCERN FOR TODAY WILL BE CLOUD COVER AND BLOWING SNOW. STRATUS IS RETURNING NORTH THIS MORNING BETWEEN JAMES AND BIG SIOUX RIVER WITH RETURN LOW LEVEL SELY FLOW. SO WUD EXPECT THIS STRATUS TO CONTINUE TO ADVECT NORTH UNDER LOW LEVEL INVERSION AND RUC SEEMS TO HANDLE THIS LOW LEVEL MOISTURE FAIRLY WELL SO WILL KEEP FAIRLY HIGH CLOUD COVER THOSE AREA THIS MORNING WITH THE INVERSION RISING A BIT BY AFTERNOON WHICH SHOULD HELP SCOUR IT OUT A BIT. NEXT IS THE INCREASING SOUTHERLY WINDS AHEAD OF NEXT WAVE THAT SHOULD GUST TO 30 TO 35 MPH LATER THIS MORNING AND AFTERNOON WHICH SHOULD CREATE AREAS OF BLOWING SNOW. WILL NOT ISSUE ANY ADVISORY AS HARD TO CREATE WIDESPREAD BLOWING PROBLEMS WHEN LOW LEVEL MOISTURE INCREASES OVER FRESH SNOW COVER. SO FOR NOW WILL JUST MENTION AREAS OF BLOWING SNOW THROUGH THE EVENING HOURS. HIGH TEMPERATURES TODAY WILL AGAIN STRUGGLE ACROSS THE EAST BUT SHOULD WARM CLOSER TO NORMAL ACROSS THE WEST. WITH STOUT SOUTHERLY FLOW TONIGHT...NOT EXPECTING TEMPERATURES TO FALL MUCH AND SHOULD ACTUALLY RISE A BIT...ESPECIALLY EAST. SYSTEM COMING OUT LATE TONIGHT AND SUNDAY A BIT SLOWER. STILL CONTINUES TO SHOW A SPLIT FLOW SYSTEM WITH ONE SYSTEM LIFTING UP ACROSS NORTHWEST CWA AND SOUTHERN WAVE MOVING NORTHEAST ACROSS CENTRAL PLAINS AND THEN PHASING EAST OF I29 SUNDAY NIGHT. WITH SLOWER SPEED THERE MAY NOT BE MUCH IF ANY PRECIPITATION ACROSS WESTERN CWA TONIGHT EXCEPT POSSIBLY FAR WESTERN CWA AFTER 09Z. WARM ENOUGH ALOFT THAT ANY PRECIPITATION WOULD BE FREEZING RAIN AND NOT SNOW SO WILL REMOVE MENTION OF SNOW LATE TONIGHT. AMOUNTS IF ANY WILL BE VERY LIGHT AND WILL NOT ISSUE ANY HEADLINE. ON SUNDAY...SOUTHERN WAVE MAY CLIP NORTHWEST IOWA DURING THE AFTERNOON AND WILL KEEP 40% POPS THERE AND LIKELY POPS ACROSS FAR NORTHWEST CWA WITH NORTHERN WAVE. IN BETWEEN WILL KEEP POPS RELATIVELY LOW IN THE 30% RANGE. DOUBT WE WILL SEE ANY FREEZING RAIN BY LATER SUNDAY MORNING AND AFTERNOON AS AIRMASS COOLS AND ANYTHING THAT DOES FALL WILL BE SNOW. SO WILL REMOVE ANY MENTION OF RAIN WEST AND WILL ALSO LOWER HIGH TEMPERATURES DUE TO THE COOLING OF THE COLUMN WITH THESE FEATURES. COULD SEE AN INCH OR TWO OF SNOW IN THE JAMES VALLEY SUNDAY AFTERNOON. GUSTY NORTHWEST WINDS WILL DEVELOP SUNDAY AFTERNOON ACROSS THE WESTERN CWA AS SURFACE TROF MOVES EAST WITH COLD AIR ADVECTION BRINGING IN STRONGER WINDS. SO COULD SEE SOME MORE BLOWING SNOW ACROSS THE WEST. SUNDAY NIGHT WILL SEE GUSTY NORTHWEST WINDS AND AREAS OF BLOWING SNOW WITH SOME LIGHT SNOW ACROSS THE CWA WITH PHASING UPPER TROF. NOT EXPECTING MUCH IN THE WAY OF ACCUMULATIONS WITH LESS THAN ONE INCH EXPECTED. ANOTHER CHILLY DAY ON MONDAY BEHIND THE WAVE WITH BELOW NORMAL TEMPERATURES EAST WITH HIGHS IN THE TEENS TO LOWER 20S. SHOULD BE A BIT WARMER WEST WITH HIGHS IN THE 20S. SURFACE HIGH WILL SETTLE ACROSS THE CWA MONDAY NIGHT...AND WITH LIGHT WINDS AND FRESH SNOW COVER...WITH GO 5 TO 10 DEGREES COLDER THAN CONSALL AND CONSRAW WHICH ARE NOT HANDLING SNOW COVER WELL AS EVIDENT BY THE VERY COLD TEMPERATURES THIS MORNING ACROSS MUCH OF CWA. WOULD NOT BE SUPRISED IF A FEW LOCATIONS ACROSS THE EAST DROP BELOW ZERO EARLY TUESDAY MORNING. SHOULD BE WARMER ACROSS THE CWA TUESDAY THROUGH FRIDAY WITH A MORE ZONAL FLOW...BUT SNOW COVER WILL HAVE A HUGE IMPACT...ESPECIALLY EAST WHERE SNOW COVER IS DEEPER AND WILL NOT MELT OFF. SO MAY AT BEST SEE HIGHS NEAR 30 ACROSS THE EAST DURING THIS TIME PERIOD...WHILE WESTERN CWA WILL HAVE A BETTER CHANCE TO MELT AWAY SOME OF THE SNOW AND APPROACH 40 FOR DAYTIME HIGHS...ESPECIALLY SOUTHWEST CWA. DOESN`T LOOK LIKE MUCH THREAT FOR ANY PRECIPITATION AFTER SUNDAY AND WILL BASICALLY KEEP CWA DRY EXPECT FOR A VERY SLIGHT CHANCE OF LIGHT SNOW TUESDAY NIGHT EAST OF I29 WITH VERY WEAK WAVE. && .FSD WATCHES/WARNINGS/ADVISORIES... SD...WIND ADVISORY THROUGH 5 PM CST FOR SDZ050-057-063. MN...NONE. IA...NONE. NE...NONE. && $$
AREA FORECAST DISCUSSION FOR SOUTHEAST SD/SOUTHWEST MN/NORTHWEST IA
NWS SIOUX FALLS SD
1100 AM CST SAT JAN 21 2012 .DISCUSSION.../ISSUED AT 1100 AM CST/ NUMEROUS UPDATES TO THE FORECAST THIS MORNING. FIRST WAS UNEXPECTED AREA OF PRECIPITATION WHICH BLOSSOMED EARLY THIS MORNING ACROSS FAR EASTERN SOUTH DAKOTA...MUCH OF NORTHWEST IOWA...AND SOUTHWEST MINNESOTA. APPARANT SOURCE OF THE SUDDEN DEVELOPMENT OF SNOWFALL WAS SEEDER FEEDER AS BLOB OF MID LEVEL CLOUDS PUSHED ACROSS THE AREA. LOWER CLOUDS WERE LIMITED TO A VERY DENDRITIC DEPTH OF 1500 TO 2500 FT THICKNESS BASED ON RUC/NAM MOISTURE PROFILES AND OBSERVED CEILINGS. FURTHER SUPPORT IS THE AREA OF MID LEVEL RETURNS NORTH OF THE CWA WHICH ARE BASED AROUND 8000-9000 FEET. AS FAST AS PRECIPITATION DEVELOPED...THIS IS ALSO ENDING JUST AS QUICKLY AROUND THE IMMEDIATE KFSD AREA. HOWEVER..AM WATCHING A COUPLE OF CLOUD LAYERS ON SATELLITE MOVING DIFFERENT DIRECTION...WITH THE LAST AREA OF MID CLOUDS IN THE JAMES VALLEY SLIDING EASTWARD. MAY GET A LITTLE BACK EDGE RESURGENCE IN SNOWFALL AS THIS AREA OF MID CLOUDS GOES PAST...BUT GENERALLY HAVE COVERAGE OF PRECIP SHIFTING EAST AND OVERALL INTENSITY OF PRECIPITATION DROPPING OFF AS WELL. LOWER CLOUDS ARE HOPELESSLY TRAPPED BELOW THE INVERSION AND CLOUD BEARING WINDS ARE NOT SUPPORTIVE OF ANY AGGRESSIVE EASTWARD PUSH. THEREFORE...UNLESS THE MOISTURE IS PRECIPITATED OUT OF THE LAYER... LIKELY THAT THERE WILL BE QUITE A FEW LOW CLOUDS FOR QUITE A BIT LONGER. RAISED THE SKYCOVER CONSIDERABLY ALONG AND EAST OF INTERSTATE 29 THIS AFTERNOON...AND TO THE WEST HIGHER CLOUDS WILL BE EVENING THE PLAYING FIELD WITH TIME AS WELL. FINALLY...ISSUED A WIND ADVISORY FOR THE HIGHER ELEVATION LOCATIONS OF SOUTH CENTRAL SD FOR REST OF THIS MORNING AND AFTERNOON...WHERE A FEW WIND GUSTS OVER 45 MPH ARE MOST LIKELY. /CHAPMAN && .AVIATION.../FOR THE 12Z TAF ISSUANCE/ AREA OF MVFR CIGS ACROSS SOUTHEAST SOUTH DAKOTA WILL MOVE ENE THIS MORNING AS SW WINDS DEVELOP ABOVE THE SURFACE. BASED UPON CURRENT MOVEMENT...LOW CLOUDS SHOULD MOVE EAST OF KHON AND KFSD BY 14Z AND KSUX BY 15Z. OTHERWISE...WINDS EXPECTED TO REALLY INCREASE THIS MORNING WITH WINDS GUSTING OVER 30 KTS EXPECTED IN MOST AREAS BY EARLY THIS AFTERNOON. WITH FRESH SNOW COVER EXPECT SOME BLOWING SNOW BUT THE BOUNDARY LAYER IS RELATIVELY STABLE WITH THE WARM AIR ADVECTION DEVELOPING SO THAT REALLY SHOULD LIMIT THE REDUCED VISIBILITIES TO ONLY A COUPLE OF HOURS THIS AFTERNOON WHEN WINDS ARE MOST LIKELY TO GUST OVER 30 KTS. WINDS WILL DECREASE A LITTLE TONIGHT AND THE MID AND UPPER CLOUDS WILL MOVE OVER. WITH A STRONG PV ANOMALY MOVING OVER THE 850 MB BOUNDARY IN CENTRAL SD LATE TONIGHT...DID BRING MVFR CIGS BACK INTO HURON LATE TONIGHT. THERE IS A LOW CHANCE OF FREEZING RAIN IN HURON AFTER 09Z BUT THE PROBABILITY IS LOW ENOUGH THAT DID NOT INCLUDE IN TAF AT THIS TIME. HOWEVER...SNOW...POSSIBLY MIXED WITH FREEZING RAIN...ARE MORE LIKELY LATE SUNDAY MORNING AND SUNDAY AFTERNOON ACROSS MOST OF SE SD AND WILL LIKELY IMPACT CIGS AND VSBYS./SCHUMACHER && .PREV DISCUSSION.../ISSUED AT 1030 AM CST/ MAIN CONCERN FOR TODAY WILL BE CLOUD COVER AND BLOWING SNOW. STRATUS IS RETURNING NORTH THIS MORNING BETWEEN JAMES AND BIG SIOUX RIVER WITH RETURN LOW LEVEL SELY FLOW. SO WUD EXPECT THIS STRATUS TO CONTINUE TO ADVECT NORTH UNDER LOW LEVEL INVERSION AND RUC SEEMS TO HANDLE THIS LOW LEVEL MOISTURE FAIRLY WELL SO WILL KEEP FAIRLY HIGH CLOUD COVER THOSE AREA THIS MORNING WITH THE INVERSION RISING A BIT BY AFTERNOON WHICH SHOULD HELP SCOUR IT OUT A BIT. NEXT IS THE INCREASING SOUTHERLY WINDS AHEAD OF NEXT WAVE THAT SHOULD GUST TO 30 TO 35 MPH LATER THIS MORNING AND AFTERNOON WHICH SHOULD CREATE AREAS OF BLOWING SNOW. WILL NOT ISSUE ANY ADVISORY AS HARD TO CREATE WIDESPREAD BLOWING PROBLEMS WHEN LOW LEVEL MOISTURE INCREASES OVER FRESH SNOW COVER. SO FOR NOW WILL JUST MENTION AREAS OF BLOWING SNOW THROUGH THE EVENING HOURS. HIGH TEMPERATURES TODAY WILL AGAIN STRUGGLE ACROSS THE EAST BUT SHOULD WARM CLOSER TO NORMAL ACROSS THE WEST. WITH STOUT SOUTHERLY FLOW TONIGHT...NOT EXPECTING TEMPERATURES TO FALL MUCH AND SHOULD ACTUALLY RISE A BIT...ESPECIALLY EAST. SYSTEM COMING OUT LATE TONIGHT AND SUNDAY A BIT SLOWER. STILL CONTINUES TO SHOW A SPLIT FLOW SYSTEM WITH ONE SYSTEM LIFTING UP ACROSS NORTHWEST CWA AND SOUTHERN WAVE MOVING NORTHEAST ACROSS CENTRAL PLAINS AND THEN PHASING EAST OF I29 SUNDAY NIGHT. WITH SLOWER SPEED THERE MAY NOT BE MUCH IF ANY PRECIPITATION ACROSS WESTERN CWA TONIGHT EXCEPT POSSIBLY FAR WESTERN CWA AFTER 09Z. WARM ENOUGH ALOFT THAT ANY PRECIPITATION WOULD BE FREEZING RAIN AND NOT SNOW SO WILL REMOVE MENTION OF SNOW LATE TONIGHT. AMOUNTS IF ANY WILL BE VERY LIGHT AND WILL NOT ISSUE ANY HEADLINE. ON SUNDAY...SOUTHERN WAVE MAY CLIP NORTHWEST IOWA DURING THE AFTERNOON AND WILL KEEP 40% POPS THERE AND LIKELY POPS ACROSS FAR NORTHWEST CWA WITH NORTHERN WAVE. IN BETWEEN WILL KEEP POPS RELATIVELY LOW IN THE 30% RANGE. DOUBT WE WILL SEE ANY FREEZING RAIN BY LATER SUNDAY MORNING AND AFTERNOON AS AIRMASS COOLS AND ANYTHING THAT DOES FALL WILL BE SNOW. SO WILL REMOVE ANY MENTION OF RAIN WEST AND WILL ALSO LOWER HIGH TEMPERATURES DUE TO THE COOLING OF THE COLUMN WITH THESE FEATURES. COULD SEE AN INCH OR TWO OF SNOW IN THE JAMES VALLEY SUNDAY AFTERNOON. GUSTY NORTHWEST WINDS WILL DEVELOP SUNDAY AFTERNOON ACROSS THE WESTERN CWA AS SURFACE TROF MOVES EAST WITH COLD AIR ADVECTION BRINGING IN STRONGER WINDS. SO COULD SEE SOME MORE BLOWING SNOW ACROSS THE WEST. SUNDAY NIGHT WILL SEE GUSTY NORTHWEST WINDS AND AREAS OF BLOWING SNOW WITH SOME LIGHT SNOW ACROSS THE CWA WITH PHASING UPPER TROF. NOT EXPECTING MUCH IN THE WAY OF ACCUMULATIONS WITH LESS THAN ONE INCH EXPECTED. ANOTHER CHILLY DAY ON MONDAY BEHIND THE WAVE WITH BELOW NORMAL TEMPERATURES EAST WITH HIGHS IN THE TEENS TO LOWER 20S. SHOULD BE A BIT WARMER WEST WITH HIGHS IN THE 20S. SURFACE HIGH WILL SETTLE ACROSS THE CWA MONDAY NIGHT...AND WITH LIGHT WINDS AND FRESH SNOW COVER...WITH GO 5 TO 10 DEGREES COLDER THAN CONSALL AND CONSRAW WHICH ARE NOT HANDLING SNOW COVER WELL AS EVIDENT BY THE VERY COLD TEMPERATURES THIS MORNING ACROSS MUCH OF CWA. WOULD NOT BE SUPRISED IF A FEW LOCATIONS ACROSS THE EAST DROP BELOW ZERO EARLY TUESDAY MORNING. SHOULD BE WARMER ACROSS THE CWA TUESDAY THROUGH FRIDAY WITH A MORE ZONAL FLOW...BUT SNOW COVER WILL HAVE A HUGE IMPACT...ESPECIALLY EAST WHERE SNOW COVER IS DEEPER AND WILL NOT MELT OFF. SO MAY AT BEST SEE HIGHS NEAR 30 ACROSS THE EAST DURING THIS TIME PERIOD...WHILE WESTERN CWA WILL HAVE A BETTER CHANCE TO MELT AWAY SOME OF THE SNOW AND APPROACH 40 FOR DAYTIME HIGHS...ESPECIALLY SOUTHWEST CWA. DOESN`T LOOK LIKE MUCH THREAT FOR ANY PRECIPITATION AFTER SUNDAY AND WILL BASICALLY KEEP CWA DRY EXPECT FOR A VERY SLIGHT CHANCE OF LIGHT SNOW TUESDAY NIGHT EAST OF I29 WITH VERY WEAK WAVE. && .FSD WATCHES/WARNINGS/ADVISORIES... SD...WIND ADVISORY THROUGH 5 PM CST FOR SDZ050-057-063. MN...NONE. IA...NONE. NE...NONE. && $$
AREA FORECAST DISCUSSION...UPDATED
NWS CORPUS CHRISTI TX
1155 AM CST SAT JAN 21 2012 .DISCUSSION...UPDATED FOR 18Z AVIATION DISCUSSION BELOW. && .AVIATION...VARIETY OF FLIGHT RULES XPCTD NEXT 24 HRS. WEAK FRONT HAS STALLED ACROSS S TX WITH KVCT/KALI REMAINING UNDER STRATUS DECK WITH IFR CIGS...KCRP IS OVERCAST WITH MVFR...AND KLRD IS AT VFR. AM XPCTING CLD DECK TO ERODE SOME THIS AFTN WITH VFR/MVFR DEVELOPING AT TIMES AT KCRP/KVCT/KALI AND VFR PREVAILING AT KLRD. STRATUS DECK LIKELY TO REDEVELOP AFTER THIS EVENING WITH ALL TERMINALS XPCTD TO TRANSITION TO MVR/IFR OVERNIGHT AND EVEN LIFR AT TIMES DUE TO LOW CIGS AND VSBYS. FOG WILL BE POSSIBLE AGAIN BUT GREATER UNCERTAINTY EXISTS REGARDING TONIGHT/S FOG POTENTIAL AS COMPARED TO PREVIOUS NIGHTS AND LATER TAF FCSTS MAY NEED TO LOWER VSBYS FOR AREA TERMINALS. IFR CIGS/VSBYS LIKELY TO PERSIST INTO SUN MRNG ALL TERMINALS. LIGHT WINDS THIS AFTN FROM N AND E BCMGING MORE SERLY TONIGHT AND SUN MRNG BUT STILL LIGHT. && .PREV DISCUSSION... /ISSUED 1046 AM CST SAT JAN 21 2012/ DISCUSSION...HAVE LET DENSE FOG ADVISORY EXPIRE AS VISIBILITIES HAVE IMPROVED. WEAK FRONT AS OF WRITING HAS MOVED THROUGH MOST OF THE AREA BUT HAS YET TO PUSH ACROSS COASTAL COUNTIES AS MARINE INFLUENCE IS HELPING STALL PROGRESSION. DRIER AIRMASS HAS FILTERED INTO NORTHERN ZONES BUT LATEST NAM AND RUC INDICATE SIGNIFICANTLY DRIER AIR WILL NOT REACH SOUTHERN COUNTIES. HAVE UPDATED SKY CONDITIONS FOR THIS AFTERNOON AND ALTERED WIND AND TEMPERATURE DATA TO REFLECT LATEST RUC AND NAM. FORECAST HIGHS ACROSS NORTHEAST COUNTIES MAY BE A LITTLE GENEROUS BUT WITH CLEARING SKIES AND DRY AIR WORKING IN TEMPS SHOULD BEGIN TO RISE SOON. WILL ALSO CONTINUE TO MONITOR MARINE CONDITIONS THROUGH THE DAY WHERE SEA FOG MAY DEVELOP AT TIMES...POSSIBLY BECOMING LOCALLY DENSE. && .PRELIMINARY POINT TEMPS/POPS... CORPUS CHRISTI 75 58 79 55 71 / 10 10 10 10 10 VICTORIA 70 53 76 50 71 / 10 10 10 10 10 LAREDO 79 61 83 54 77 / 0 0 10 10 10 ALICE 78 58 82 55 74 / 0 10 10 10 10 ROCKPORT 69 58 75 56 66 / 10 10 10 10 10 COTULLA 76 53 81 48 74 / 0 0 10 10 10 KINGSVILLE 79 58 81 56 73 / 0 10 10 10 10 NAVY CORPUS 72 58 75 58 67 / 10 10 10 10 10 && .CRP WATCHES/WARNINGS/ADVISORIES... TX...NONE. GM...NONE. && $$ AVIATION...HART/79
AREA FORECAST DISCUSSION...UPDATED
NWS CORPUS CHRISTI TX
1046 AM CST SAT JAN 21 2012 .DISCUSSION...HAVE LET DENSE FOG ADVISORY EXPIRE AS VISIBILITIES HAVE IMPROVED. WEAK FRONT AS OF WRITING HAS MOVED THROUGH MOST OF THE AREA BUT HAS YET TO PUSH ACROSS COASTAL COUNTIES AS MARINE INFLUENCE IS HELPING STALL PROGRESSION. DRIER AIRMASS HAS FILTERED INTO NORTHERN ZONES BUT LATEST NAM AND RUC INDICATE SIGNIFICANTLY DRIER AIR WILL NOT REACH SOUTHERN COUNTIES. HAVE UPDATED SKY CONDITIONS FOR THIS AFTERNOON AND ALTERED WIND AND TEMPERATURE DATA TO REFLECT LATEST RUC AND NAM. FORECAST HIGHS ACROSS NORTHEAST COUNTIES MAY BE A LITTLE GENEROUS BUT WITH CLEARING SKIES AND DRY AIR WORKING IN TEMPS SHOULD BEGIN TO RISE SOON. WILL ALSO CONTINUE TO MONITOR MARINE CONDITIONS THROUGH THE DAY WHERE SEA FOG MAY DEVELOP AT TIMES...POSSIBLY BECOMING LOCALLY DENSE. && .PRELIMINARY POINT TEMPS/POPS... CORPUS CHRISTI 75 58 79 55 71 / 10 10 10 10 10 VICTORIA 70 53 76 50 71 / 10 10 10 10 10 LAREDO 79 61 83 54 77 / 0 0 10 10 10 ALICE 78 58 82 55 74 / 0 10 10 10 10 ROCKPORT 69 58 75 56 66 / 10 10 10 10 10 COTULLA 76 53 81 48 74 / 0 0 10 10 10 KINGSVILLE 79 58 81 56 73 / 0 10 10 10 10 NAVY CORPUS 72 58 75 58 67 / 10 10 10 10 10 && .CRP WATCHES/WARNINGS/ADVISORIES... TX...NONE. GM...NONE. && $$ UPDATE...HART/79
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
319 PM CST SAT JAN 21 2012 .SHORT TERM...TONIGHT THROUGH MONDAY 319 PM CST SAT JAN 21 2012 MAIN FOCUS IS ON A VARIETY OF PRECIPITATION TYPES FOR LATER TONIGHT THROUGH MONDAY. CURRENTLY AS OF 20Z...WATER VAPOR LOOP AND RUC 500MB HEIGHT ANALYSIS SHOWED TROUGHING OVER THE WESTERN U.S....RIDGING ACROSS MUCH OF THE PLAINS...AND TROUGHING OVER SOUTHEAST CANADA. 500MB HEIGHT FALLS IN 12 HOURS ARE AS MUCH AS 170 METERS WITH THE WESTERN TROUGH ACCORDING TO THE RUC...CENTERED OVER EASTERN NEVADA. THE FORECAST AREA RESIDES ON THE EAST SIDE OF THE RIDGING...FAVORING HIGH PRESSURE AT THE SURFACE. THIS HIGH WAS CENTERED OVER LAKE MICHIGAN...AFTER BEING OVER THE FORECAST AREA EARLY THIS MORNING WHICH ALLOWED FOR THE 10 TO 20 BELOW ZERO READINGS. SOUTHERLY FLOW IS INCREASING ON THE BACK SIDE OF THE HIGH...ESPECIALLY ACROSS THE PLAINS AHEAD OF A LEE TROUGH. 850MB PROFILER AND RUC WIND DATA SHOWED SOUTHWEST WINDS OF 35-50 KT FROM KANSAS INTO THE EASTERN DAKOTAS AND WESTERN MINNESOTA. SOUNDINGS SHOW SOME STRONG WARMING AT 850MB AS A RESULT OF THE INCREASING WINDS. BETWEEN 00Z AND 12Z...850MB TEMPS ROSE FROM -11C TO -2C AT OAX...-11C TO +2C AT LBF AND -14C TO +6C AT UNR. THE SOUTHERLY FLOW IS ALSO ADVECTING STRATUS THAT WAS JUST SOUTH OF THE FORECAST AREA THIS MORNING BACK TO THE NORTHWEST. THE STRATUS DECK NOW COVERS MUCH OF IOWA AND THE WESTERN HALF OF MINNESOTA. LAST ITEM OF NOTE IS A LARGE AREA OF STRATUS ALONG THE GULF COAST...AS WELL AS HIGHER SURFACE DEWPOINTS. THIS MOISTURE IS IMPORTANT FOR TOMORROW. MODEL ANALYSIS...MODELS ARE STILL HAVING SOME ISSUES WITH THE TROUGHING OVER THE WESTERN U.S. AS IT TRACKS INTO THE PLAINS ON SUNDAY. THE GFS/ECMWF/CANADIAN ARE BY FAR THE DEEPEST... ESPECIALLY WHEN IT COMES TO THE SHORTWAVE AT THE BASE OF THE TROUGH WHICH CROSSES THE SOUTHERN PLAINS. THE ECMWF HAS BEEN EXTREMELY CONSISTENT WITH THE GFS AND CANADIAN TRENDING RAPIDLY TOWARDS THE ECMWF. AS SUCH...THESE MODELS ALLOW FOR THAT SHORTWAVE TO TURN NEGATIVE TILT AND LIFT INTO ILLINOIS SUNDAY NIGHT. IMMEDIATELY AHEAD OF THIS SHORTWAVE THERE IS A DEEPENING SURFACE LOW...WHICH ENDS UP TRACKING FROM OKLAHOMA ON SUNDAY TO NEAR MILWAUKEE AT 12Z MONDAY. THE 21.12Z NAM CONTINUES TO SUGGEST A LITTLE MORE PROGRESSIVE TROUGH AND LESS FOCUS ON THE NEGATIVELY TILT SHORTWAVE...RESULTING IN THE SURFACE LOW TRACKING FROM SOUTH DAKOTA ON SUNDAY TO THUNDER BAY ONTARIO BY 12Z MONDAY. BASED ON HOW POTENT THE TROUGH LOOKS CROSSING NEVADA THIS AFTERNOON...NOTED TOO BY THE LIGHTNING ASSOCIATED WITH IT... THINK THE DEEPER GFS/ECMWF SCENARIOS ARE MORE LIKELY TO OCCUR. TONIGHT...LOW LEVEL SOUTHERLY FLOW WILL INCREASE TONIGHT AS THE WESTERN U.S. TROUGH BEGINS TO MOVE INTO THE WESTERN SIDE OF THE PLAINS. AS THIS SOUTHERLY FLOW INCREASES...THE STRATUS TO OUR SOUTH AND WEST WILL GRADUALLY OVERSPREAD THE FORECAST AREA...TAKING THE LONGEST OVER WISCONSIN. IN ADDITION...TEMPERATURES AND DEWPOINTS SHOULD RISE AS THE WARMER READINGS TO THE SOUTH ADVECT NORTHWARD. A BIG CONCERN IS SOME OF THE FLURRY ACTIVITY THAT HAS ALREADY OCCURRED IN THE STRATUS DECK. THERE ARE INDICATIONS THAT THE LIFT PRODUCING THESE FLURRIES WILL OCCUR AT LEAST OVER NORTHWEST SECTIONS OF THE FORECAST AREA AFTER MIDNIGHT...AND PERHAPS WESTERN SECTIONS TOO. HOWEVER...AS THE TEMPERATURES IN THE STRATUS DECK WARM...WORRIED THAT WE MAY LOSE ICE PRODUCTION...RESULTING IN FREEZING DRIZZLE. PLACED BOTH A MENTION OF FLURRIES AND PATCHY FREEZING DRIZZLE AFTER MIDNIGHT OVER NORTHWEST SECTIONS. SUNDAY...STRONG SOUTHERLY FLOW LOOKS TO CONTINUE WITH THE AREA STILL AHEAD OF THE UPPER TROUGH MOVING INTO THE PLAINS...AS WELL AS THE ASSOCIATED SURFACE TROUGH/LOW. THIS SOUTH FLOW SHOULD BRING THE WARMER AND MORE MOIST AIR ALONG THE GULF COAST NORTHWARD INTO THE FORECAST AREA. AS A RESULT...THE STRATUS DECK OVER THE FORECAST AREA SHOULD DEEPEN THROUGH THE DAY. WITH THE STRATUS DECK WARMER THAN -10C OVER MUCH OF THE AREA THROUGH THE ENTIRE DAY...ENVISIONING ONLY DRIZZLE. THERE ARE INDICATIONS OF MID AND UPPER LEVEL CLOUDS COMING ACROSS...WITH LIFT THERE TOO TO PRODUCE ICE...BUT THE DRY LAYER BETWEEN THESE CLOUDS AND THE LOW STRATUS IS DEEPER AND DRIER THAN PROGGED TWO DAYS AGO. THEREFORE...ANY ICE PRODUCED ALOFT SHOULD EVAPORATE BEFORE REACHING THE STRATUS. EVEN IF IT DID REACH THE STRATUS...THE DRY LAYER HAS TEMPERATURES PROGGED AT 3-6C WHICH WOULD TEND TO MELT THE ICE. LIFT WITHIN THE STRATUS DECK IS PROGGED TO INCREASE TOO THROUGH THE DAY...NOTED ON 280-285K SURFACES...WHICH MAY RESULT IN A CHANGE FROM DRIZZLE TO RAIN. HOWEVER...NONE OF THE LIFT IS ALL THAT STRONG...SO KEPT THINGS SIMPLE AND STATED DRIZZLE ALL DAY. QPF/ICE AMOUNTS LIKELY TO BE ONE TO THREE HUNDREDTHS. WHERE FREEZING DRIZZLE AND DRIZZLE OCCURS WILL BE DICTATED BY SURFACE TEMPERATURE...TO SOME DEGREE. ONE ISSUE IS THAT WE HAVE HAD A LOT OF COLD TEMPERATURES RECENTLY...SO EVEN WHERE TEMPERATURES CLIMB ABOVE FREEZING...UNTREATED SURFACES MAY ICE UP. KEPT PRECIPITATION CHANCES LOW SINCE THERE STILL IS UNCERTAINTY ON HOW MUCH DRIZZLE WILL FALL. MOS GUIDANCE QUITE LOW ON NUMBERS...THOUGH 21.15Z SREF DOES INDICATE 60-70 PERCENT OF MEMBERS PRODUCING A 0.01 OR MORE OF QPF. WITH PRECIPITATION CHANCES RIGHT NOW FORECAST AT BELOW 60 PERCENT...AND PER COLLABORATION WITH SURROUNDING OFFICES...HELD OFF ON ANY FREEZING RAIN ADVISORY FOR NOW. DO FEEL THAT AN ADVISORY WILL BE NEEDED. SUNDAY NIGHT INTO MONDAY...AS THE LOW DEEPENS AND LIFTS OFF TO THE NORTHEAST SUNDAY NIGHT...COLDER AIR WILL GRADUALLY FILTER SOUTHEAST INTO THE FORECAST AREA FROM THE NORTHERN PLAINS. HOW FAST THIS OCCURS DEPENDS ON THE EXACT TRACK OF THE LOW...WHICH IS STILL FAR FROM CERTAIN. THEREFORE...POTENTIAL REMAINS FOR DRIZZLE/FREEZING RAIN UNTIL THE LOW PASSES. EVEN THEN...DEPENDING ON THE LOW TRACK...THERE COULD STILL BE A WARM LAYER ALOFT THAT HAS TO COOL.. RESULTING IN MIXED PRECIPITATION TYPES. FOR NOW...JUST STUCK WITH A DRIZZLE/FREEZING DRIZZLE EVENING CHANGING OVER TO RAIN/SNOW AFTER MIDNIGHT. NEEDLESS TO SAY MORE MODIFICATION WILL BE NEEDED FOR SUNDAY NIGHT...POSSIBLY INTO EARLY MONDAY AS WELL. SNOW SHOULD SLOWLY TAPER OFF SOUTHWEST TO NORTHEAST MONDAY AS THE LOW PULLS AWAY FROM THE AREA. DID RAISE PRECIPITATION CHANCES MONDAY MORNING...THOUGH...WITH GOOD CONSENSUS OF WRAP AROUND PRECIPITATION IN THE AREA. SHOULD SEE TEMPERATURES CLIMB SOME SUNDAY NIGHT AS THE LOW APPROACHES...THEN SLOWLY FALL ON MONDAY AS THE LOW MOVES AWAY. WINDS SHOULD PICK UP TOO ON MONDAY...ESPECIALLY OVER THE WIND FAVORED AREAS OF SOUTHEAST MINNESOTA AND NORTHEAST IOWA. LOOKS LIKE WINDS SHOULD STAY WELL BELOW ADVISORY...THOUGH. .LONG TERM...MONDAY NIGHT THROUGH SATURDAY 319 PM CST SAT JAN 21 2012 AFTER AN ACTIVE SHORT TERM PERIOD...LONG TERM FORECAST AT LEAST AT THIS TIME LOOKS FAIRLY BENIGN. IN THE MEAN...ALL MODELS ARE IN AGREEMENT OF A FAST WEST-NORTHWEST PATTERN FROM THE PACIFIC NORTHWEST INTO OUR REGION...WHICH MAY BECOME A LITTLE MORE NORTHWESTERLY ON SATURDAY WITH INDICATIONS OF A SHORTWAVE TROUGH DIGGING DOWN INTO THE FORECAST AREA. THIS PATTERN WILL SUPPORT A FLOW OF MILD PACIFIC AIR INTO THE FORECAST AREA...NOTED BY 850MB TEMPS THAT STRUGGLE TO GET COLDER THAN -6C FOR THE MOST PART UNTIL SATURDAY. THERE ARE A FEW SHORTWAVE TROUGHS PROGGED TO MOVE THROUGH THE AREA...ONE TUESDAY NIGHT AND WEDNESDAY...AND ANOTHER ON THURSDAY. NEITHER OF THESE FEATURES PRODUCE MUCH QPF IN MODEL OUTPUT...PRIMARILY BECAUSE THEY DO NOT HAVE MUCH MOISTURE TO WORK WITH. THE SYSTEM IN THE SHORT TERM PERIOD PRETTY MUCH SHUNTS ALL MOISTURE SOUTH AND EAST OF THE AREA. THEREFORE...ONLY SOME SLIGHT CHANCES REMAIN FOR TUESDAY NIGHT THROUGH WEDNESDAY NIGHT. PRECIPITATION TYPE MAY HAVE TO BE WATCHED FOR THIS TIME PERIOD...GIVEN THE MILDER 850MB TEMPS. WOULD NOT BE SURPRISED TO SEE EITHER MIXES WITH RAIN...OR WORSE A LOSS OF ICE RESULTING IN RAIN/FREEZING RAIN VERSUS SNOW. KEPT PRECIPITATION TYPES AS SNOW SINCE BOTH DETAILS ARE VERY UNCERTAIN AT THIS TIME. FOR MUCH OF THE LONG TERM PERIOD...FOLLOWED A CONSENSUS BLEND OF GUIDANCE FOR BOTH TEMPERATURES AND PRECIPITATION THROUGHOUT THE LONG TERM PERIOD. && .AVIATION...THROUGH 18Z SUNDAY 1137 AM CST SAT JAN 21 2012 FIRST ISSUE TO CONTEND WITH IS THE LOW CLOUDS ON THE EDGE OF THE SURFACE RIDGE AXIS AND HOW FAST THEY POSSIBLY RETURN TO THE AREA. BOTH THE 21.12Z NAM AND 21.15Z RUC SHOW THIS LOW LEVEL MOISTURE SURGING NORTH INTO WESTERN AND CENTRAL MINNESOTA DURING THE EVENING. AT THE SAME TIME...A POCKET OF DRY AIR...CURRENTLY OVER NORTHERN INDIANA AND EASTERN ILLINOIS...GETS PULLED NORTH INTO WISCONSIN. BOTH MODELS ARE REMARKABLY SIMILAR IN SHOWING THE MOISTURE AND LOW CLOUDS RETURNING TO KRST THIS EVENING AROUND 03Z WITH THE DRY AIR HOLDING ON AT KLSE WELL INTO THE NIGHT. THUS DID NOT RETURN THE LOW CLOUDS TO KLSE UNTIL 08Z. THE NEXT ISSUE IS WHEN AND IF THERE WILL BE ANY PRECIPITATION ONCE THE LOW CLOUDS MOVE IN. AGAIN THE NAM AND RUC ARE IN GOOD AGREEMENT IN SHOWING THE WARM AIR ADVECTION AND OMEGA IN THE 0-2KM LAYER TO BE MAXIMIZED TONIGHT NORTH OF BOTH TAF SITES SO DID NOT INITIALLY ADD ANY PRECIPITATION WITH THE RETURN OF THE LOW CLOUDS. LOOKING AT THE BUFKIT SOUNDINGS...IT LOOKS LIKE IT WILL TAKE UNTIL SUNDAY MORNING BEFORE THE DEPTH OF THE SATURATED LAYER AND THE OMEGA THROUGH IT BECOME SUFFICIENT TO SUPPORT ANY PRECIPITATION. ONCE THIS OCCURS...THE PRECIPITATION SHOULD BE FREEZING DRIZZLE AS THE DEPTH OF SATURATION IS NOT ENOUGH TO SUPPORT ANY ICE IN THE CLOUDS. HAVE THUS ADDED THIS TO BOTH TAF SITES IN THE 14 TO 15Z TIME FRAME. THE FINAL THING TO CONTEND WITH IS THE POSSIBILITY OF LOW LEVEL WIND SHEAR OVERNIGHT. AS THE LOW LEVEL RIDGE AXIS MOVES OFF TONIGHT AND STRONG LOW LEVEL LOW PRESSURE BEGINS TO TAKE SHAPE EAST OF THE ROCKIES...THE LOW LEVEL WINDS ARE EXPECTED TO INCREASE RAPIDLY ABOVE THE SURFACE INVERSION. WINDS AT 2000 FEET ARE EXPECTED TO INCREASE TO THE 35 TO 45 KNOT RANGE THIS EVENING AND EVEN POSSIBLY INCREASE SOME OVERNIGHT. THIS WILL CREATE ABOUT A 25 KNOT DIFFERENCE IN SPEEDS WITH SOME SLIGHT CHANGE IN WIND DIRECTION AND HAVE INCLUDED WIND SHEAR AT BOTH TAF SITES UNTIL THE INVERSION IS EXPECTED TO START WEAKENING SUNDAY MORNING. && .ARX WATCHES/WARNINGS/ADVISORIES... 319 PM CST SAT JAN 21 2012 WI...NONE. MN...NONE. IA...NONE. && $$ SHORT TERM...AJ LONG TERM...AJ AVIATION...04
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
1137 AM CST SAT JAN 21 2012 .SHORT TERM...TODAY THROUGH MONDAY NIGHT 230 AM CST SAT JAN 21 2012 PROBLEMATIC FORECAST FOR SUNDAY-SUNDAY NIGHT AS A COMPLEX SCENARIO BRINGS THE THREAT FOR A WINTERY MIX. A 500 MB TROUGH STILL SET TO MOVE EAST OUT OF THE ROCKIES...THEN NORTHEAST ACROSS THE GREAT LAKES BY 12Z MON. MODEL DIFFERENCES CONTINUE...WITH THE 21.00Z NAM REMAINING THE QUICKER MODEL. IT MOVES ITS ASSOCIATED SFC LOW OVER LAKE SUPERIOR BY 06Z MON WHILE THE GFS WOULD SLIDE ITS LOW OVER SOUTHERN WI BY THIS TIME. MEANWHILE...THE EC CONTINUES TO BE THE SLOWER MODEL...HOLDING ITS SFC LOW BACK OVER NORTHERN MO...NOT MOVING IT INTO SOUTHEAST WI UNTIL 12Z MON. THE 21.00Z GEM IS CLOSE TO THE EC...WITH THE GFS SEEMING TO BE TRENDING MORE TOWARD THIS SLOWER SOLUTION. THE NAM IS THE ODD MODEL OUT AND WILL CRAFT THE FORECAST TOWARD A GFS/EC BLEND. WHILE THE BRUNT OF THE UPPER LEVEL FORCING WON/T SHIFT ACROSS THE REGION UNTIL SUNDAY NIGHT...THERE IS SOME LOW LEVEL WARM AIR ADVECTION AND A BIT OF ISENTROPIC UPGLIDE TO CONTEND WITH. NORTHWEST-SOUTHEAST RUNNING X-SECTIONS/BUFKIT SOUNDINGS SHOW AN INCREASE IN THE NEAR SFC SATURATION...BUT ONLY TO ABOUT 850 MB BY THE AFTERNOON. WITH A GOOD AMOUNT OF WARMING IN THE 925-850 MB LAYER...THERE WILL BE NO ICE IN THE CLOUD...AND ANY PCPN GENERATED FROM THE THERMODYNAMICS WOULD BE LIQUID/FREEZING - DEPENDING ON SFC TEMPS. PROBABLY MORE A DRIZZLE THREAT IN THE MORNING...AND DEEPENING SATURATION IN THE AFTERNOON MAKING RAIN A BIT MORE LIKELY...IF ANYTHING WOULD OCCUR. TO MAKE IT LESS COMPLEX...WILL STAY WITH RAIN/FREEZING RAIN WORDING FOR NOW. THE GFS AND GEM BOTH PRODUCE SOME LIGHT QPF ON SUNDAY...AND IF THIS MANIFESTS...SOME ICY SPOTS WOULD DEVELOP WHERE SFC TEMPS ALLOWED. ON THE PLUS SIDE...IT DOES LOOK LIKE A GOOD PORTION OF THE FORECAST AREA WOULD WARM ABOVE FREEZING SUNDAY AFTERNOON. THAT SAID...EXPOSED SFCS COULD STILL ALLOW FOR FREEZING THANKS TO THE RECENT BOUT OF COLD DAYS. THE SATURATION DEEPENS SUN EVENING...AND THAT WILL RESULT IN A CHANGE OVER TO SNOW AS ICE IS INTRODUCED INTO THE CLOUD. THIS CHANGE OVER WILL COINCIDE WITH THE SHORTWAVE MOVING IN...ALONG WITH STRONGER 700-300 MB QG CONVERGENCE AND SOME FRONTOGENETIC FORCING IN THE 700-500 MB LAYER. MUCH OF THE EVENING COULD STILL SEE MORE OF A RAIN/FREEZING RAIN THREAT THOUGH. THE LOW PRESSURE SYSTEM WILL EXIT INTO SOUTHEAST CANADA MON EVENING...AND DROP A COUPLE INCHES OF SNOW ACCUMULATION TO NORTHERN PORTIONS OF THE FORECAST BY THE TIME IT EXITS. ALL IN ALL THOUGH...THE MIXED PCPN AND THREAT FOR FREEZING RAIN/FREEZING DRIZZLE APPEARS TO BE THE MAIN CONCERN WITH THIS WEATHER SYSTEM. ITS EVOLUTION WILL BE MONITORED CLOSELY. ASIDE FROM THE MIXED BAG OF WINTER WEATHER...THE LOW WILL ALSO USHER IN A COUPLE WINDY DAYS. SOUTH WINDS WILL PICK UP TONIGHT AND PERSIST FOR THE EARLY PART OF SUNDAY...AND WILL BE RATHER BLUSTERY AT TIMES. INCREASING PRESSURE GRADIENT ON THE BACKSIDE OF THE DEPARTING LOW WILL RESULT IN BLUSTERY NORTHWEST WINDS FOR MONDAY. WHILE WARMER AIR RETURNS WITH THE SOUTHERLY FETCH...COLD AIR WILL FOLLOW WITH THE NORTHWEST WINDS...AND HIGHS MONDAY WILL LIKELY OCCUR EARLY IN THE DAY - STEADY TO SLOWLY FALLING FOR THE REST OF THE DAY. .LONG TERM...TUESDAY THROUGH FRIDAY 230 AM CST SAT JAN 21 2012 THE GFS AND EC FAVOR SLIDING A SHORTWAVE TROUGH THROUGH A SFC HIGH TUE NIGHT...BUT ACROSS NORTHERN PORTIONS OF THE REGION. CURRENT TRACK WOULD APPEAR TO HAVE MINIMAL IMPACT ON THE LOCAL AREA. THE EC THEN BRINGS A SHARPER/STRONGER UPPER LEVEL TROUGH OVER THE UPPER MISSISSIPPI RIVER VALLEY FOR WED NIGHT/THU. IT WILL HAVE TO BRING ITS OWN MOISTURE AND CURRENT QPF VIA THE EC KEEPS THE BETTER PCPN CHANCES OVER NORTHERN/EASTERN WI. MEANWHILE...THE GFS IS BASICALLY DRY AS IT HAS ONLY A RIPPLE MOVING NORTH OF THE REGION. THE GEM IS MORE LIKE THE EC...WHILE THE EC HAS BEEN A BIT MORE CONSISTENT WITHIN ITSELF COMPARED TO THE GFS. WILL LEAN ON THE EC/GEM/CONSENSUS FOR DETAILS IN THIS PERIOD. THE MOSTLY ZONAL FLOW A LOFT LOOKS FAIRLY ACTIVE NEXT WEEK WITH THE MODELS THEN SUGGESTING ANOTHER SHORTWAVE TROUGH ON EITHER THU-FRI...DEPENDING ON WHICH MODEL YOU PREFER. THE GFS IS QUICKER THAN THE EC...AND WILL AGAIN SIDE WITH EC/CONSENSUS FOR NOW. STILL...IT LOOKS LIKE THE BETTER PCPN CHANCES MAY HOLD NORTH OF THE FORECAST AREA. && .AVIATION...THROUGH 18Z SUNDAY 1137 AM CST SAT JAN 21 2012 FIRST ISSUE TO CONTEND WITH IS THE LOW CLOUDS ON THE EDGE OF THE SURFACE RIDGE AXIS AND HOW FAST THEY POSSIBLY RETURN TO THE AREA. BOTH THE 21.12Z NAM AND 21.15Z RUC SHOW THIS LOW LEVEL MOISTURE SURGING NORTH INTO WESTERN AND CENTRAL MINNESOTA DURING THE EVENING. AT THE SAME TIME...A POCKET OF DRY AIR...CURRENTLY OVER NORTHERN INDIANA AND EASTERN ILLINOIS...GETS PULLED NORTH INTO WISCONSIN. BOTH MODELS ARE REMARKABLY SIMILAR IN SHOWING THE MOISTURE AND LOW CLOUDS RETURNING TO KRST THIS EVENING AROUND 03Z WITH THE DRY AIR HOLDING ON AT KLSE WELL INTO THE NIGHT. THUS DID NOT RETURN THE LOW CLOUDS TO KLSE UNTIL 08Z. THE NEXT ISSUE IS WHEN AND IF THERE WILL BE ANY PRECIPITATION ONCE THE LOW CLOUDS MOVE IN. AGAIN THE NAM AND RUC ARE IN GOOD AGREEMENT IN SHOWING THE WARM AIR ADVECTION AND OMEGA IN THE 0-2KM LAYER TO BE MAXIMIZED TONIGHT NORTH OF BOTH TAF SITES SO DID NOT INITIALLY ADD ANY PRECIPITATION WITH THE RETURN OF THE LOW CLOUDS. LOOKING AT THE BUFKIT SOUNDINGS...IT LOOKS LIKE IT WILL TAKE UNTIL SUNDAY MORNING BEFORE THE DEPTH OF THE SATURATED LAYER AND THE OMEGA THROUGH IT BECOME SUFFICIENT TO SUPPORT ANY PRECIPITATION. ONCE THIS OCCURS...THE PRECIPITATION SHOULD BE FREEZING DRIZZLE AS THE DEPTH OF SATURATION IS NOT ENOUGH TO SUPPORT ANY ICE IN THE CLOUDS. HAVE THUS ADDED THIS TO BOTH TAF SITES IN THE 14 TO 15Z TIME FRAME. THE FINAL THING TO CONTEND WITH IS THE POSSIBILITY OF LOW LEVEL WIND SHEAR OVERNIGHT. AS THE LOW LEVEL RIDGE AXIS MOVES OFF TONIGHT AND STRONG LOW LEVEL LOW PRESSURE BEGINS TO TAKE SHAPE EAST OF THE ROCKIES...THE LOW LEVEL WINDS ARE EXPECTED TO INCREASE RAPIDLY ABOVE THE SURFACE INVERSION. WINDS AT 2000 FEET ARE EXPECTED TO INCREASE TO THE 35 TO 45 KNOT RANGE THIS EVENING AND EVEN POSSIBLY INCREASE SOME OVERNIGHT. THIS WILL CREATE ABOUT A 25 KNOT DIFFERENCE IN SPEEDS WITH SOME SLIGHT CHANGE IN WIND DIRECTION AND HAVE INCLUDED WIND SHEAR AT BOTH TAF SITES UNTIL THE INVERSION IS EXPECTED TO START WEAKENING SUNDAY MORNING. && .ARX WATCHES/WARNINGS/ADVISORIES... 230 AM CST SAT JAN 21 2012 WI...NONE. MN...NONE. IA...NONE. && $$ SHORT TERM... RIECK LONG TERM.... RIECK AVIATION...04
AREA FORECAST DISCUSSION
NWS MILWAUKEE/SULLIVAN WI
1116 AM CST SAT JAN 21 2012 .AVIATION/18Z TAFS/...VFR SKC FOR MUCH OF THE CWA INTO THE EVENING HOURS. ONLY CONCERN AREA IS FROM NEAR KMKE SOUTH TO KENW WHERE LAKE EFFECT MVFR CLOUDS WILL SKIRT THIS AREA. LOW LEVEL RH PROGS HAVE A PRETTY GOOD HANDLE ON LOCATION OF STRATUS FIELD TO OUR SOUTH AND SOUTHWEST. THIS WILL START COMING BACK LATER TONIGHT INTO SUNDAY AS FLOW TURNS MORE SOUTHERLY. BUFKIT SOUNDINGS SHOW CONSIDERABLE MOISTENING IN THE LOW LAYERS...SO WHILE THE INCREASE WILL INITIALLY BE MVFR...AS MOISTURE INCREASES...WILL SEE IFR AND SOME LIFR TAKING SHAPE AS WELL. WILL HOLD OFF ON ANY MENTION OF DZ/FZDZ IN THE TAFS THROUGH 18Z. BETTER POTENTIAL AFTER 18Z...BUT CONFIDENCE LOW AT THIS POINT. TEMPS PROGGD IN MANY AREAS TO RISE ABOVE FREEZING MARK BY ONSET TIME...ESPECIALLY IN EASTERN WI. PC && .PREV DISCUSSION... /ISSUED 317 AM CST SAT JAN 21 2012/ TODAY AND TONIGHT...FORECAST CONFIDENCE...MEDIUM NEAR LAKE MICHIGAN THE MAIN ISSUE WILL BE HANDLING LAKE EFFECT TRENDS. NORTHEAST WINDS IN SHALLOW LAYER FROM 975 MB TO 900 MB. LAPSE RATES ARE NOT TO STEEP WITH AROUND 3 C/KM AT MILWAUKEE BUT NEAR 6C/KM NEAR KENOSHA AT 09Z BUT LAPSE RATES INCREASE TO NEAR 9C/KM AT 18Z WITH INVERSION HEIGHT AROUND 3 THSD FT. LOW LEVEL FLOW WEAKENS AND BECOMES MORE EAST. THEREFORE EXPECT THE SNOW BAND NEAR KENOSHA TO CONTINUE TO WEAKEN AND THEN EVENTUALLY BECOME MORE DIFFUSE WITH GENERAL LIGHT SNOW/FLURRIES NEAR THE LAKE. HRRR SHOWS THE LAKE BAND PUSHING SOUTH THEN WEAKENING BUT INCREASING IN COVERAGE. NAM SHOWS SOMETHING SIMILAR. ELSEWHERE MOISTURE TRAPPED BLOW DEVELOPING INVERSION AROUND 3 THSD FT SHOULD SLOW ANY CLEARING FROM THE WEST. FORECAST SOUNDINGS SHOW SOME CLEARING POTENTIAL OVER THE FRINGES OF THE STRATUS SHIELD BUT THEN WITH THE EAST FLOW...LOW LEVELS MOISTEN SO STRATUS/STRATOCUMULUS COULD EXPAND AGAIN. MID LEVEL SHORTWAVE OVER THE EASTERN GREAT LAKES EXITS TO THE EAST WITH MID LEVEL DRYING. STRONG SHORTWAVE OVER THE PACIFIC NORTHWEST WILL REACH THE ROCKIES TONIGHT. LOW/MID LEVEL WARM AIR ADVECTION BEGINS BUT THE 850 TO 700 MB LAYER IS FAIRLY DRY SO NOT EXPECTING ANY PRECIPITATION. BY MIDNIGHT SOUNDINGS SHOW TEMPERATURES AROUND 800 MB ALREADY WARMING ABOVE 0 CELSIUS OVER MUCH OF THE FORECAST AREA...AND ABOVE 0 C BY SUNRISE. NAM SHOWS SATURATION BELOW 925 MB BUT DOES NOT APPEAR DEEP ENOUGH MOIST LAYER FOR FREEZING DRIZZLE. SUNDAY AND MONDAY...FORECAST CONFIDENCE...MEDIUM MODELS SLOWLY COMING INTO BETTER AGREEMENT FOR THE SUNDAY/MONDAY LOW PRESSURE SYSTEM. THE GFS HAS TRENDED TOWARD THE SLOWER ECMWF AND CANADIAN SOLUTIONS...WHILE THE NAM REMAINS THE QUICKEST. LEANED FORECAST PRETTY HEAVILY TOWARD CONSISTENT ECMWF. OVERALL...LOOKS LIKE A CHANCE FOR WARM ADVECTION PRECIP ON SUNDAY. MID LEVELS ARE QUITE DRY IN SOUNDINGS...WITH VERY LITTLE ICE EXPECTED. WITH SFC TEMPS BELOW FREEZING TO START THE DAY...KEPT MENTION OF FREEZING RAIN. MENTIONED RAIN A CHANCE FOR RAIN AS WELL IN THE AFTERNOON AS TEMPS WARM ABOVE FREEZING. ONLY REASON SNOW WAS LEFT IN FOR SUNDAY IS THAT SOME MODELS DO SHOW SOME ICE CRYSTAL POTENTIAL ABOVE THE DRY LAYER. DRY LAYER LOOKS LIKE IT WILL GENERALLY DRY UP ANY ICE...BUT POTENTIAL FOR SEEDING IS THERE IF DRY LAYER IS OVERDONE IN MODELS. PRECIP AMOUNTS EXPECTED TO BE LIGHT DURING THE DAY SUNDAY...SO ANY ICING WOULD BE FAIRLY LIMITED. SFC LOW EXPECTED TO MOVE THROUGH SUNDAY NIGHT...ALONG WITH BEST SHOT FOR PRECIP FROM THIS STORM. ENOUGH OVERLAP BETWEEN MODELS TO BUMP POPS UP TO CATEGORICAL. LOOKS LIKE MAINLY RAIN EAST...MIXING WITH SNOW WEST. MAY SEE EVENTUAL CHANGE OVER TO SNOW WEST TO EAST BEGINNING LATE SUNDAY NIGHT OR MONDAY MORNING...WITH SOME LIGHT ACCUMULATIONS POSSIBLE. WITH DEWPOINTS EXPECTED TO GET INTO THE MID 30S OVER THE SNOWPACK...AND THE SFC LOW COMING RIGHT OVERHEAD...MENTIONED PATCHY FOG IN THE EAST SUN NIGHT AND MON MORNING. TUESDAY THROUGH FRIDAY...FORECAST CONFIDENCE...MEDIUM LOOKS FAIRLY QUIET TUESDAY THROUGH THE REMAINDER OF THE WORK WEEK. MODELS DEPICTING A SERIES OF WEAK SHORTWAVES TO ROLL THROUGH DURING THIS PERIOD...POSSIBLY BRINGING SOME FLURRIES OR LIGHT SNOW AT TIMES. NEAR NORMAL TEMPS TUESDAY EXPECTED TO WARM TO A FEW DEGREES ABOVE NORMAL FOR WEDNESDAY THROUGH FRIDAY. AVIATION/12Z TAFS/... MAINLY MVFR CIGS OVER FAR SOUTH CENTRAL AND PORTIONS OF SOUTHEAST WISCONSIN. LAKE BAND PUSHING SOUTH BUT STRONGEST RADAR RETURNS HAVE BEEN STAYING OFF SHORE. AS LOW LEVEL FLOW BECOMES MORE EAST LAKE EFFECT WILL EXPAND IN COVERAGE BUT SHOULD BE FAIRLY LIGHT...ALTHOUGH SOME AREAS COULD SEE SOME VERY LIGHT ACCUMULATIONS. CIGS/VSBYS WILL BE MAINLY MVFR. THE LOW CLOUD SHIELD MAY ERODE SOMEWHAT FROM THE WEST...BUT THEN WOULD TEND TO EXPAND AGAIN AS EAST FLOW INCREASES THE LOW LEVEL MOISTURE. IFR POTENTIAL LATER TONIGHT AS EAST/SOUTHEAST FLOW INCREASES. MARINE... A SMALL CRAFT ADVISORY WILL LIKELY BE NEEDED LATE TONIGHT THROUGH MONDAY NIGHT AS LOW PRESSURE MOVES EAST AND EXITS THE NORTHERN PLAINS. BRISK SOUTH WINDS AND HIGH WAVES WILL PREVAIL SATURDAY NIGHT INTO SUNDAY NIGHT. A COLD FRONT WILL THEN SHIFT THE WINDS TO THE WEST FOR LATE SUNDAY NIGHT AND INTO MONDAY NIGHT. THE WINDS WILL CONTINUE TO BE BRISK AND GUSTY AND SMALL CRAFT CONDITIONS WILL LIKELY PERSIST FOR THIS TIME PERIOD. && .MKX WATCHES/WARNINGS/ADVISORIES... WI...NONE. LM...NONE. && $$ TODAY/TONIGHT AND AVIATION/MARINE...HENTZ SUNDAY THROUGH FRIDAY...DDV