Forecast Discussions mentioning any of "HRRR" "RAP" "RR" "RUC13" "RUC" received at GSD on 12/09/12


AREA FORECAST DISCUSSION
NWS DENVER/BOULDER CO
352 PM MST FRI DEC 7 2012 .SHORT TERM...SNOW STILL ONGOING ACROSS MOUNTAINS...WITH SOME ENHANCEMENT SHOWING UP ON RADAR ALONG THE CONTINENTAL DIVIDE. LATEST WATER VAPOR INDICATE SOME SORT OF WAVE MOVING ACROSS WYOMING WHICH MAY BE HELPING WITH THE SNOWFALL. ACROSS PLAINS...SURGE MOVED ACROSS AREA WITH NORTHEAST WINDS UP TO THE FOOTHILLS. LATEST RUC CROSS SECTIONS CONTINUE TO SHOW GOOD MOISTURE ACROSS THE MOUNTAINS THROUGH TONIGHT AND OROGRAPHICS SHOULD HELP TO KEEP SOME SNOW GOING THOUGH THERE APPEARS FROM UPSTREAM OBSERVATIONS AND SATELLITE OF A BREAK IN THE MOISTURE. SO THERE MAY BE SOME DECREASE IN THE SNOW AND WILL MAINTAIN THE CHANCE POPS. WINDS TO INCREASE TONIGHT AHEAD OF AN APPROACHING SYSTEM. LATEST MODELS CONTINUE TO SHOW THE DEVELOPMENT OF A DECENT MOUNTAIN WAVE AND MOUNTAIN TOP INVERSION AFTER MIDNIGHT...WITH RUC CROSS SECTIONS INDICATING 40 KTS OF CROSS MOUNTAIN FLOW BY 08Z. LATEST NAM CROSS SECTIONS INDICATING EVEN STRONGER CROSS MOUNTAIN FLOW OVERNIGHT AND INTO MUCH OF SATURDAY...AROUND 45 KTS AT MOUNTAIN TOP AT 09Z TO A WHOPPING 75 KTS FROM 15Z TO ROUGHLY 21Z. THESE VALUES LOOK A BIT OVERDONE...BUT MODELS ARE STILL SIMILAR IN SHOWING HIGH WIND POTENTIAL FOR THE MOUNTAINS AS WELL AS THE FOOTHILLS...THOUGH THE SHEAR MAY NOT IDEAL AND INVERSION MAY BE BREAKING UP AS PATTERN TRANSITIONS FROM A CHINOOK PATTERN OVERNIGHT TO A BORA PATTERN BY SATURDAY AFTERNOON WHEN THE MID LEVEL ASCENT INCREASES. BEST TIME FOR THE HIGH WINDS THREAT WILL BE 09Z TO 21Z SATURDAY. WILL ISSUE A HIGH WIND WARNING FOR THE MOUNTAINS AND FOOTHILLS FROM 06Z FRIDAY THROUGH 00Z SUNDAY...OR BASICALLY ALL OF SATURDAY. SHOULD SEE GUSTS OF AT LEAST 75 MPH DURING THIS TIME FRAME. SHOULD ALSO SEE SNOW INCREASE AROUND 18Z SATURDAY ACROSS THE MOUNTAINS AS THE JET SAGS INTO THE STATE AND LIFT INCREASES WITH UP TO 4 INCHES POSSIBLE BY THE EVENING. WINDS WILL ALSO CREATE BLOWING SNOW...MAINLY DURING THE AFTERNOON. ACROSS PLAINS...CLOUDS TO GRADUALLY INCREASE THIS EVENING AS WINDS SHIFT TO A DRAINAGE PATTERN. WINDS MAY GET A BIT GUSTY NEAR THE FOOTHILLS OVERNIGHT AS DOWNSLOPE WINDS DEVELOP. ON SATURDAY...MODELS CONTINUE TO SNOW CANADIAN FRONT MOVING ACROSS THE AREA DURING THE AFTERNOON...WITH NORTHEAST UPSLOPE WINDS HOLDING OFF UNTIL THE EVENING. GFS SHOWS SOME PRECIP ALONG THE NORTHEAST CORNER LATE IN THE AFTERNOON. FOR NOW WILL KEEP THINGS DRY THROUGH THE AFTERNOON. COLDER AIR TO MOVING INTO THE AREA AFTER 00Z. .LONG TERM...A SWIFT RIVER OF MOIST PACIFIC AIR ROUNDING THE SOUTH SIDE OF A BROAD UPPER LEVEL TROUGH IS FORECAST TO BECOME POSITIONED OVER NORTHERN COLORADO SATURDAY NIGHT. MODELS SHOW A 110-130KT WEST- EAST ORIENTED JET AT THE CORE OF THIS FLOW OVER THE COLORADO FRONT RANGE MTNS FOR MOST OF SATURDAY NIGHT. HOWEVER THROUGH THE NIGHT MODELS SHOW THE UPPER TROUGH DIGGING SOUTHWARD TOWARD THE FOUR CORNERS WITH THE MEAN FLOW ALOFT BECOMING PROGRESSIVELY MORE NORTHERLY IN DIRECTION AND SPEEDS DECREASING SUBSTANTIALLY SUNDAY MORNING WITH THE BACK SIDE OF TROUGH SHIFTING EASTWARD. CROSS SECTIONS INDICATE CROSS BARRIER WINDS OVERNIGHT ON THE ORDER OF 45- 55KTS AT MTN TIME LEVEL. THE STRONG WINDS WILL LIKELY COMBINE WITH SNOWFALL AND LIGHT TO MODERATE ACCUMULATIONS TO PRODUCE AREAS OF BLOWING SNOW IN THE HIGH COUNTRY...PARTICULARLY ON THE HIGH MTN PASSES AND UP AROUND THE EISENHOWER TUNNEL OVERNIGHT. MAY BECOME NECESSARY TO HOIST A WINTER WEATHER ADVISORY FOR SNOW AND BLOWING SNOW FOR THE MTN AND FTHLS ZONES SHOULD THE NEXT MODEL RUN INDICATE A SIMILAR SETUP. AT LOWER ELEVATIONS EAST OF THE MTNS...CANADIAN COLD FRONT DROPS SOUTH ACROSS THE NORTHEAST PLAINS OF COLORADO EARLY SATURDAY AS PER LATEST MODEL GUIDANCE FOLLOWED BY 6-9 HOURS OF NORTH- NORTHEAST SFC-700 MB FLOW. SNOW CHANCES AND AMOUNTS EAST OF THE MTNS LOOKING LESS IMPRESSIVE WITH THE 12Z AND 18Z MODEL RUNS. MODEL SNOW GRIDS CONFINE THE BULK OF SNOW ACCUMULATION RIGHT UP AGAINST THE FRONT RANGE FOOTHILLS AND OVER THE PALMER DIVIDE. MODELS BARELY SHOW ANY SNOW ACCUMULATION EAST OF I-25 OR NORTH OF U.S. HIGHWAY 6 FOR THIS STORM SYSTEM. OVERALL MODELS HAVE BEEN ALL OVER THE PLACE WITH SNOW TOTALS AND COVERAGE...BUT ONE MODEL...THE NAM...HAS CONSISTENTLY SHOWED LITTLE IF ANY SNOW EAST OF THE MTNS. FOR THIS FCST PACKAGE LARGELY RELIED ON THE SREF TO LOAD QPF AND SNOW AMTS IN THE FORECAST GRIDS. LOOKING AHEAD TO SUNDAY...SHOULD SEE SNOWFALL DIMINISHING FORM NORTH TO SOUTH IN THE MTNS AND NEARBY PLAINS THROUGH THE DAY...WITH LITTLE ADDITIONAL ACCUMULATION ANTICIPATED. MAIN CONCERN ON SUNDAY WILL BE THE MUCH BELOW AVERAGE TEMPERATURES AND BITTER WIND CHILLS WITH NORTHERLY WINDS OF 10-25 MPH. DO NOT EXPECTED TO SEE DAYTIME TEMPERATURES CLIMBING ABOVE THE UPPER 20S ANYWHERE IN THE FORECAST AREA. WITH CLEARING SKIES OVERNIGHT...GOOD BET WE/LL SEE THE COLDEST TEMPERATURES DO THE WINTER SEASON THUS FAR...WITH MTN VALLEYS MERCURY READINGS WELL BELOW ZERO BY MORNING. FOR MONDAY...ANOTHER SYSTEM RACES OUT OF THE PACIFIC NORTHWEST AND ACROSS COLORADO BRINGING ANOTHER SHOT OF SNOW AND WIND TO THE MTNS AND HIGH VALLEYS. COULD SEE A BIT OF LIGHT SNOW DURING THE AFTERNOON/EVENING ON THE NORTHEAST PLAINS WITH ANTICYCLONIC UPSLOPE FLOW FOR A TIME. NEW ACCUMULATIONS SHOULD BE LIGHT AND CONFINED TO AREAS ABOVE TIMBERLINE AND NORTHWEST FACING MTN SLOPES. LATER IN THE WEEK...SHOULD SEE A GRADUAL RETURN TO WARMER AND DRIER CONDITIONS. && .AVIATION...EASTERLY WINDS TO GRADUALLY DECREASE AND SWITCH TO DRAINAGE DURING THE EVENING. SPEEDS OF AROUND 10 KTS TO PREVAIL THOUGH SOME GUSTS TO 25 KTS POSSIBLE AT BJC AS DOWNSLOPE FLOW DEVELOPS. WINDS TO SHIFT TO THE NORTHWEST BY 18Z THEN NORTH AROUND 21Z AS FRONT MOVES ACROSS AREA. COULD SEE SOME GUSTS TO 25 KTS WITH FRONTAL PASSAGE. VFR CONDITIONS TO PREVAIL WITH A GRADUAL INCREASE IN MID AND HIGH LEVEL MOISTURE. CEILINGS OF AROUND 6000 FEET COULD DEVELOP AFTER 21Z WITH POTENTIAL FOR ILS IMPACTS. PRECIPITATION SHOULD HOLD OFF UNTIL THE EVENING WHEN THE COLDER AIR MOVES OVER THE AREA. && .BOU WATCHES/WARNINGS/ADVISORIES... HIGH WIND WARNING FROM 11 PM THIS EVENING TO 5 PM MST SATURDAY FOR COZ033>036. && $$ SHORT TERM...D-L LONG TERM....BAKER AVIATION...D-L
AREA FORECAST DISCUSSION
NWS DENVER/BOULDER CO
1237 PM MST FRI DEC 7 2012 .UPDATE... && .SHORT TERM...NORTHEAST SURGE CURRENTLY PUSHING SOUTH AND WEST ACROSS PLAINS...A BIT STRONGER THAN PREVIOUSLY THOUGHT...WITH SOME GUSTS AROUND 22 KTS. UPDATED WIND GRIDS FOR THIS CHANGE. SHOULD SEE SOME DECREASE IN SPEEDS AFTER 21Z...PER LATEST RUC. THE RUC ALSO BEGINNING TO GENERATE SOME LIGHT QPF ACROSS PORTIONS OF THE PLAINS THROUGH 02Z. FOR NOW WILL KEEP OUT OF GRIDS BUT WILL NEED TO MONITOR. .AVIATION...TAFS UPDATED FOR STRONGER NORTHEAST PUSH ACROSS AREA AIRPORTS...WITH DECREASING SPEEDS BY 21Z AS WINDS SHIFT TO THE SOUTHEAST. BEGINNING TO SEE SOME CEILINGS AROUND 7000 FEET AGL DEVELOPING NORTH AND EAST OF DENVER. WILL NEED TO MONITOR IF LOWER CEILINGS DEVELOP. && .PREV DISCUSSION... /ISSUED 948 AM MST FRI DEC 7 2012/ UPDATE... SHORT TERM...WAVE CURRENTLY ACROSS EASTERN PLAINS WITH MID LEVEL SUBSIDENCE SPREADING ACROSS MOUNTAINS AND FOOTHILLS. WEB CAMS SHOWING MOUNTAIN SNOW ON THE DECREASE WITH LOSS OF LIFT. STILL GOOD OROGRAPHICS FOR SOME SNOW TO CONTINUE THROUGH THE AFTERNOON MAINLY WEST FACING SLOPES. ANY ADDITIONAL ACCUMULATION TO BE MINIMAL. WINDS GUSTY ACROSS RIDGES AND ALONG FOOTHILLS IN WAKE OF THE WAVE...BEING ENHANCED BY THE SUBSIDENCE. MODELS SHOW SOME DECREASE IN THE WINDS BELOW THE RIDGES BY THE AFTERNOON. OVERALL CURRENT FORECASTS SEEM TO BE HANDLING THE TRENDS NICELY...THOUGH WINDS MAY NEED A BIT OF TWEEKING. STRONGER WINDS STILL EXPECTED AFTER MIDNIGHT AHEAD OF A STRONGER SYSTEM. STILL SOME QUESTION WHETHER SPEEDS WILL REACH HIGH WIND CRITERIA LATE TONIGHT INTO SATURDAY MORNING DUE TO RATHER UNFAVORABLE SHEAR PROFILE. FOR NOW THE CURRENT GUSTS IN THE 40 TO 60 MPH IN THE FOOTHILLS SEEM REASONABLE. WILL LOOK FURTHER INTO THIS FOR THE AFTERNOON ISSUANCE. AVIATION...CURRENT TAF TRENDS STILL LOOKING ON TRACK. MODELS CONTINUE TO SHOW WINDS TRANSITIONING TO THE NORTH NORTHWEST BY 18Z...THEN EAST TO SOUTHEAST AROUND 00Z. RUC DOES HOLD ONTO THE NORTHERLIES THROUGH 02Z. WILL CONTINUE THE ONGOING TAF TRENDS FOR THE UPCOMING ISSUANCE. PREV DISCUSSION... /ISSUED 455 AM MST FRI DEC 7 2012/ SHORT TERM...ANOTHER WEAK SHORTWAVE IS PASSING OVER THIS MORNING...ENOUGH TO KEEP SOME MID LEVEL CLOUD AROUND IN ADDITION TO THE UBIQUITOUS WAVE CLOUDS...AND A COUPLE BANDS OF SNOW SHOWERS DRAGGING ACROSS THE NORTHERN MOUNTAINS THIS MORNING. WEBCAMS SHOW SOME ACCUMULATION AT THE EISENHOWER TUNNEL OVER THE LAST 3 HOURS...BUT TOTALS SHOULD BE 2 INCHES OR LESS. SOME DECREASE IN THE MOISTURE AS WEAK SUBSIDENCE BEHIND THE WAVE COMES IN THIS AFTERNOON...BUT THERE WILL LIKELY STILL BE SOME CLOUDS ESPECIALLY UPSTREAM OF THE MOUNTAINS. SURFACE PRESSURE FALL/RISE COUPLET WITH TODAYS WAVE IS MAINLY PASSING NORTH OF US...BUT WILL STILL SERVE TO GIVE US A NORTHERLY COMPONENT TO THE LOW LEVEL WINDS ON THE PLAINS TODAY AND A LITTLE COOLING BOTH AT THE SURFACE AND ALOFT ALONG THE NORTHERN BORDER. WILL HANG ON TO THE HIGHS WE HAVE FORECAST...BUT IF THE CLOUD COVER REMAINS THICK WE WILL NEED TO TRIM THEM BACK A BIT. TONIGHT THE WINDS INCREASE AHEAD OF THE STRONGER WEEKEND SYSTEM. GOOD PROFILE FOR A MOUNTAIN WAVE OVERNIGHT...THOUGH THE MID LEVEL FLOW IS NOT TOO STRONG UNTIL MORNING...AND BY THEN THE INVERSION IS BREAKING DOWN AS COLD ADVECTION DEVELOPS. SHEAR IS ALSO A BIT STRONGER THAN OPTIMAL...BUT NOT TOO MUCH. SO WE WILL BE TRANSITIONING FROM A CHINOOK LIKE WAVE SETUP OVERNIGHT TO MORE OF A BORA/BRUTE FORCE DOWNSLOPE TYPE WAVE SATURDAY MORNING THAT SHOULD BRING HIGHER SPEEDS INTO THE LOWER FOOTHILLS...WHILE THE PROSPECT FOR MUCH AMPLIFICATION SHOULD BE LESSENING. HIGH WIND THREAT IS PROBABLY GREATEST IN THIS TRANSITION TIME EARLY SATURDAY...AT THIS POINT IT LOOKS LIKE THE HIGH WIND THREAT IS GREATEST IN THE HIGHER ELEVATIONS OF THE FRONT RANGE...SO I WILL BE INCREASING SPEEDS BUT WILL NOT GO WITH A WATCH AT THIS TIME...THINKING GUSTS OF 40-60 MPH IN THE FOOTHILLS OVERNIGHT. MOISTURE WILL ALSO BE INCREASING AGAIN WITH THICKENING CLOUDS AND A BETTER CHANCE OF LIGHT SNOW AGAIN IN THE MOUNTAINS TOWARD MORNING. LONG TERM...MODELS SHOW A WESTERLY JET MAXIMUM TO SAG SOUTHWARD INTO THE NORTHERN CWA THROUGH THE DAY SATURDAY AS A MEAN UPPER TROUGH DEVELOPS OVER A GOOD PORTION OF NORTH AMERICA. THIS JET MAX CONTINUES PUSHING SOUTHWARD SATURDAY NIGHT AND OUT OF THE CWA BY 12Z SUNDAY MORNING. SPEEDS ARE IN THE 100-110 KNOT RANGE. ON SUNDAY...THE UPPER TROUGH AXIS MOVES EASTWARD ACROSS THE CWA. BY EARLY SUNDAY EVENING IT IS EAST OF COLORADO AND STRONG NORTH- NORTHWESTERLY FLOW ALOFT IS AT HAND FOR THE CWA. THE QG VERTICAL VELOCITY FIELDS HAVE A BATCH OF WEAK UPWARD MOTION PROGGED SATURDAY MORNING...THEN ANOTHER SHOT FROM 06Z TO 18Z SUNDAY MORNING. BY SUNDAY AFTERNOON AND EVENING...DOWNWARD MOTION IS PROGGED. THE LOW LEVEL WINDS ARE PROGGED TO BE DOWNSLOPING MUCH OF SATURDAY...SOUTHWESTERLY OR WESTERLY IN DIRECTION. THERE IS STILL A LINGERING MOUNTAIN WAVE SET UP SATURDAY MORNING. THIS SHOULD BRING PRETTY STRONG DOWNSLOPING FLOW TO THE HIGHER FOOTHILLS AND MOUNTAINS. A COLD FRONT AND UPSLOPE IS EXPECTED TO MOVE INTO THE CWA LATE SATURDAY. THE NAM SHOWS MORE OF A 330-340 DEGREE WIND DIRECTION IN THE BOUNDARY LAYER. THE GFS AND ECMWF SHOW MORE TEXT BOOK UPSLOPE...360 TO 030 DEGREES. THE NORTHERLY LOW LEVEL FLOW IS PROGGED TO CONTINUE THROUGH SUNDAY...WITH DOWNSLOPING SUNDAY NIGHT AFTER THE UPPER TROUGH AXIS PASSES. THE UPSLOPE FLOW IS FAIRLY DEEP...UP TO AROUND 600 MB ON THE MODELS. FOR MOISTURE .MODELS ARE SOMEWHAT DRIER OVERALL COMPARED TO YESTERDAY`S 00Z RUNS. MOISTURE INCREASES THROUGH THE DAY ON SATURDAY IN THE MOUNTAINS...GETTING PRETTY DEEP BY 00Z SATURDAY EARLY EVENING. THE PLAINS JUST HAVE SOME MOISTURE AROUND IN THE MID LEVELS AT THAT TIME. MOISTURE GETS FAIRLY DEEP OVER THE PLAINS SATURDAY NIGHT INTO HALF OF SUNDAY ON THE GFS AND ECMWF...THE NAM IS STILL WAY DRIER. THE MOUNTAINS HAVE DEEP MOISTURE SATURDAY INTO EARLY SUNDAY TOO. BY SUNDAY AFTERNOON...MOISTURE DECREASES OVER ALL THE CWA...THIS TREND CONTINUES SUNDAY NIGHT AS WELL. THE QPF FIELDS SHOW THE BEST ACCUMULATIONS IN THE MOUNTAINS AND FOOTHILLS SATURDAY THROUGH SUNDAY AFTERNOON...ALTHOUGH VALUES ARE NOT SIGNIFICANT. THE NAM HAS LESS THAN THE GFS AND ECMWF. THERE IS NO MEASURABLE PRECIPITATION ON THE QPF FIELDS SUNDAY NIGHT. FOR POPS...WILL STAY THE COURSE...BUT WILL KEEP THE PLAINS DRY ALL DAY SATURDAY...JUST A TAD IN THE FOOTHILLS BY LATER AFTERNOON. THE ONLY "LIKELY"S WILL STILL BE IN THE MOUNTAINS FOR THIS UPDATE. WILL END ALL POPS BY LATE SUNDAY AFTERNOON. NO HIGHLIGHTS NEEDED. IT SHOULD SNOW. I AM JUST RELUCTANT TO GO ALL OUT WITH THE NAM BEING TO OUT OF SINK AND EVEN THE LATEST GFS SHOWING LESS MOISTURE. FOR TEMPERATURES...SATURDAY`S HIGHS WILL BE 1-3 C COOLER THAN TODAY`S. SUNDAY`S HIGHS WILL BE 10-14 C COLDER THAN SATURDAY`S. IF SUNDAY NIGHT DOES INDEED CLEAR OUT...LOWS IN THE GFE GRIDS FOR THAT PERIOD MAY NEED TO BE LOWERED YET MORE. FOR THE LATER DAYS...MONDAY THROUGH THURSDAY...MODELS KEEP WEST- NORTHWESTERLY FLOW ALOFT OVER THE CWA MONDAY INTO TUESDAY. A WEAK TROUGH IS PROGGED TO MOVE ACROSS COLORADO TUESDAY AFTERNOON. DIFFERENT FROM YESTERDAY. THERE IS SOME UPPER RIDGING ON WEDNESDAY. BY WEDNESDAY NIGHT AND THURSDAY...PRETTY STRONG WEST- SOUTHWESTERLY FLOW ALOFT IS PROGGED FOR THE FORECAST AREA AS AN UPPER TROUGH DEVELOPS IN THE GREAT BASIN. THE GFS HAS QUITE A BIT OF MOUNTAIN MOISTURE IN PLACE BY MONDAY AFTERNOON...THE ECMWF NOT UNTIL MONDAY NIGHT. THE MOISTURE IS MOSTLY GONE BY MID DAY TUESDAY. THEN IS IT PRETTY DRY WELL INTO THURSDAY. TEMPERATURES COULD GET TO OR A TAD ABOVE NORMALS ON WEDNESDAY ONLY. THURSDAY COOLS BACK DOWN. AVIATION...VFR CONDITIONS WITH LIGHT WINDS TODAY...THERE MAY BE SOME VARIABILITY IN THE WINDS BUT THE GENERAL TREND WILL BE TO ROTATE FROM WEST OR NORTHWEST THIS MORNING THROUGH NORTH OR NORTHEAST THIS AFTERNOON AND BACK AROUND TO SOUTH THIS EVENING. && .BOU WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...D-L LONG TERM....RJK AVIATION...D-L
AREA FORECAST DISCUSSION
NWS DENVER/BOULDER CO
948 AM MST FRI DEC 7 2012 .UPDATE... && .SHORT TERM...WAVE CURRENTLY ACROSS EASTERN PLAINS WITH MID LEVEL SUBSIDENCE SPREADING ACROSS MOUNTAINS AND FOOTHILLS. WEB CAMS SHOWING MOUNTAIN SNOW ON THE DECREASE WITH LOSS OF LIFT. STILL GOOD OROGRAPHICS FOR SOME SNOW TO CONTINUE THROUGH THE AFTERNOON MAINLY WEST FACING SLOPES. ANY ADDITIONAL ACCUMULATION TO BE MINIMAL. WINDS GUSTY ACROSS RIDGES AND ALONG FOOTHILLS IN WAKE OF THE WAVE...BEING ENHANCED BY THE SUBSIDENCE. MODELS SHOW SOME DECREASE IN THE WINDS BELOW THE RIDGES BY THE AFTERNOON. OVERALL CURRENT FORECASTS SEEM TO BE HANDLING THE TRENDS NICELY...THOUGH WINDS MAY NEED A BIT OF TWEEKING. STRONGER WINDS STILL EXPECTED AFTER MIDNIGHT AHEAD OF A STRONGER SYSTEM. STILL SOME QUESTION WHETHER SPEEDS WILL REACH HIGH WIND CRITERIA LATE TONIGHT INTO SATURDAY MORNING DUE TO RATHER UNFAVORABLE SHEAR PROFILE. FOR NOW THE CURRENT GUSTS IN THE 40 TO 60 MPH IN THE FOOTHILLS SEEM REASONABLE. WILL LOOK FURTHER INTO THIS FOR THE AFTERNOON ISSUANCE. .AVIATION...CURRENT TAF TRENDS STILL LOOKING ON TRACK. MODELS CONTINUE TO SHOW WINDS TRANSITIONING TO THE NORTH NORTHWEST BY 18Z...THEN EAST TO SOUTHEAST AROUND 00Z. RUC DOES HOLD ONTO THE NORTHERLIES THROUGH 02Z. WILL CONTINUE THE ONGOING TAF TRENDS FOR THE UPCOMING ISSUANCE. && .PREV DISCUSSION... /ISSUED 455 AM MST FRI DEC 7 2012/ SHORT TERM...ANOTHER WEAK SHORTWAVE IS PASSING OVER THIS MORNING...ENOUGH TO KEEP SOME MID LEVEL CLOUD AROUND IN ADDITION TO THE UBIQUITOUS WAVE CLOUDS...AND A COUPLE BANDS OF SNOW SHOWERS DRAGGING ACROSS THE NORTHERN MOUNTAINS THIS MORNING. WEBCAMS SHOW SOME ACCUMULATION AT THE EISENHOWER TUNNEL OVER THE LAST 3 HOURS...BUT TOTALS SHOULD BE 2 INCHES OR LESS. SOME DECREASE IN THE MOISTURE AS WEAK SUBSIDENCE BEHIND THE WAVE COMES IN THIS AFTERNOON...BUT THERE WILL LIKELY STILL BE SOME CLOUDS ESPECIALLY UPSTREAM OF THE MOUNTAINS. SURFACE PRESSURE FALL/RISE COUPLET WITH TODAYS WAVE IS MAINLY PASSING NORTH OF US...BUT WILL STILL SERVE TO GIVE US A NORTHERLY COMPONENT TO THE LOW LEVEL WINDS ON THE PLAINS TODAY AND A LITTLE COOLING BOTH AT THE SURFACE AND ALOFT ALONG THE NORTHERN BORDER. WILL HANG ON TO THE HIGHS WE HAVE FORECAST...BUT IF THE CLOUD COVER REMAINS THICK WE WILL NEED TO TRIM THEM BACK A BIT. TONIGHT THE WINDS INCREASE AHEAD OF THE STRONGER WEEKEND SYSTEM. GOOD PROFILE FOR A MOUNTAIN WAVE OVERNIGHT...THOUGH THE MID LEVEL FLOW IS NOT TOO STRONG UNTIL MORNING...AND BY THEN THE INVERSION IS BREAKING DOWN AS COLD ADVECTION DEVELOPS. SHEAR IS ALSO A BIT STRONGER THAN OPTIMAL...BUT NOT TOO MUCH. SO WE WILL BE TRANSITIONING FROM A CHINOOK LIKE WAVE SETUP OVERNIGHT TO MORE OF A BORA/BRUTE FORCE DOWNSLOPE TYPE WAVE SATURDAY MORNING THAT SHOULD BRING HIGHER SPEEDS INTO THE LOWER FOOTHILLS...WHILE THE PROSPECT FOR MUCH AMPLIFICATION SHOULD BE LESSENING. HIGH WIND THREAT IS PROBABLY GREATEST IN THIS TRANSITION TIME EARLY SATURDAY...AT THIS POINT IT LOOKS LIKE THE HIGH WIND THREAT IS GREATEST IN THE HIGHER ELEVATIONS OF THE FRONT RANGE...SO I WILL BE INCREASING SPEEDS BUT WILL NOT GO WITH A WATCH AT THIS TIME...THINKING GUSTS OF 40-60 MPH IN THE FOOTHILLS OVERNIGHT. MOISTURE WILL ALSO BE INCREASING AGAIN WITH THICKENING CLOUDS AND A BETTER CHANCE OF LIGHT SNOW AGAIN IN THE MOUNTAINS TOWARD MORNING. LONG TERM...MODELS SHOW A WESTERLY JET MAXIMUM TO SAG SOUTHWARD INTO THE NORTHERN CWA THROUGH THE DAY SATURDAY AS A MEAN UPPER TROUGH DEVELOPS OVER A GOOD PORTION OF NORTH AMERICA. THIS JET MAX CONTINUES PUSHING SOUTHWARD SATURDAY NIGHT AND OUT OF THE CWA BY 12Z SUNDAY MORNING. SPEEDS ARE IN THE 100-110 KNOT RANGE. ON SUNDAY...THE UPPER TROUGH AXIS MOVES EASTWARD ACROSS THE CWA. BY EARLY SUNDAY EVENING IT IS EAST OF COLORADO AND STRONG NORTH- NORTHWESTERLY FLOW ALOFT IS AT HAND FOR THE CWA. THE QG VERTICAL VELOCITY FIELDS HAVE A BATCH OF WEAK UPWARD MOTION PROGGED SATURDAY MORNING...THEN ANOTHER SHOT FROM 06Z TO 18Z SUNDAY MORNING. BY SUNDAY AFTERNOON AND EVENING...DOWNWARD MOTION IS PROGGED. THE LOW LEVEL WINDS ARE PROGGED TO BE DOWNSLOPING MUCH OF SATURDAY...SOUTHWESTERLY OR WESTERLY IN DIRECTION. THERE IS STILL A LINGERING MOUNTAIN WAVE SET UP SATURDAY MORNING. THIS SHOULD BRING PRETTY STRONG DOWNSLOPING FLOW TO THE HIGHER FOOTHILLS AND MOUNTAINS. A COLD FRONT AND UPSLOPE IS EXPECTED TO MOVE INTO THE CWA LATE SATURDAY. THE NAM SHOWS MORE OF A 330-340 DEGREE WIND DIRECTION IN THE BOUNDARY LAYER. THE GFS AND ECMWF SHOW MORE TEXT BOOK UPSLOPE...360 TO 030 DEGREES. THE NORTHERLY LOW LEVEL FLOW IS PROGGED TO CONTINUE THROUGH SUNDAY...WITH DOWNSLOPING SUNDAY NIGHT AFTER THE UPPER TROUGH AXIS PASSES. THE UPSLOPE FLOW IS FAIRLY DEEP...UP TO AROUND 600 MB ON THE MODELS. FOR MOISTURE ..MODELS ARE SOMEWHAT DRIER OVERALL COMPARED TO YESTERDAY`S 00Z RUNS. MOISTURE INCREASES THROUGH THE DAY ON SATURDAY IN THE MOUNTAINS...GETTING PRETTY DEEP BY 00Z SATURDAY EARLY EVENING. THE PLAINS JUST HAVE SOME MOISTURE AROUND IN THE MID LEVELS AT THAT TIME. MOISTURE GETS FAIRLY DEEP OVER THE PLAINS SATURDAY NIGHT INTO HALF OF SUNDAY ON THE GFS AND ECMWF...THE NAM IS STILL WAY DRIER. THE MOUNTAINS HAVE DEEP MOISTURE SATURDAY INTO EARLY SUNDAY TOO. BY SUNDAY AFTERNOON...MOISTURE DECREASES OVER ALL THE CWA...THIS TREND CONTINUES SUNDAY NIGHT AS WELL. THE QPF FIELDS SHOW THE BEST ACCUMULATIONS IN THE MOUNTAINS AND FOOTHILLS SATURDAY THROUGH SUNDAY AFTERNOON...ALTHOUGH VALUES ARE NOT SIGNIFICANT. THE NAM HAS LESS THAN THE GFS AND ECMWF. THERE IS NO MEASURABLE PRECIPITATION ON THE QPF FIELDS SUNDAY NIGHT. FOR POPS...WILL STAY THE COURSE...BUT WILL KEEP THE PLAINS DRY ALL DAY SATURDAY...JUST A TAD IN THE FOOTHILLS BY LATER AFTERNOON. THE ONLY "LIKELY"S WILL STILL BE IN THE MOUNTAINS FOR THIS UPDATE. WILL END ALL POPS BY LATE SUNDAY AFTERNOON. NO HIGHLIGHTS NEEDED. IT SHOULD SNOW. I AM JUST RELUCTANT TO GO ALL OUT WITH THE NAM BEING TO OUT OF SINK AND EVEN THE LATEST GFS SHOWING LESS MOISTURE. FOR TEMPERATURES...SATURDAY`S HIGHS WILL BE 1-3 C COOLER THAN TODAY`S. SUNDAY`S HIGHS WILL BE 10-14 C COLDER THAN SATURDAY`S. IF SUNDAY NIGHT DOES INDEED CLEAR OUT...LOWS IN THE GFE GRIDS FOR THAT PERIOD MAY NEED TO BE LOWERED YET MORE. FOR THE LATER DAYS...MONDAY THROUGH THURSDAY...MODELS KEEP WEST- NORTHWESTERLY FLOW ALOFT OVER THE CWA MONDAY INTO TUESDAY. A WEAK TROUGH IS PROGGED TO MOVE ACROSS COLORADO TUESDAY AFTERNOON. DIFFERENT FROM YESTERDAY. THERE IS SOME UPPER RIDGING ON WEDNESDAY. BY WEDNESDAY NIGHT AND THURSDAY...PRETTY STRONG WEST- SOUTHWESTERLY FLOW ALOFT IS PROGGED FOR THE FORECAST AREA AS AN UPPER TROUGH DEVELOPS IN THE GREAT BASIN. THE GFS HAS QUITE A BIT OF MOUNTAIN MOISTURE IN PLACE BY MONDAY AFTERNOON...THE ECMWF NOT UNTIL MONDAY NIGHT. THE MOISTURE IS MOSTLY GONE BY MID DAY TUESDAY. THEN IS IT PRETTY DRY WELL INTO THURSDAY. TEMPERATURES COULD GET TO OR A TAD ABOVE NORMALS ON WEDNESDAY ONLY. THURSDAY COOLS BACK DOWN. AVIATION...VFR CONDITIONS WITH LIGHT WINDS TODAY...THERE MAY BE SOME VARIABILITY IN THE WINDS BUT THE GENERAL TREND WILL BE TO ROTATE FROM WEST OR NORTHWEST THIS MORNING THROUGH NORTH OR NORTHEAST THIS AFTERNOON AND BACK AROUND TO SOUTH THIS EVENING. && .BOU WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...D-L LONG TERM....RJK AVIATION...D-L
AREA FORECAST DISCUSSION
NWS TALLAHASSEE FL
317 PM EST Fri Dec 7 2012 .NEAR TERM [Tonight]... Objective RUC analysis shows a subtle surface convergence zone coincident with a ribbon of higher 0-1km mixing ratios stretching from coastal MS/AL southeastward into the eastern Gulf of Mexico. There have been some scattered showers in this area for the bulk of the day, and they are expected to continue overnight and into Saturday morning. For tonight, they should remain mostly in our western marine zones. However over time the 0-1km flow will veer to a more southerly direction, which should allow some of the showers to begin affecting our far western land zones (SE AL and the western FL Panhandle). This is expected to be after 12z Saturday, so the overnight forecast was kept dry for now. The only other concern is for some fog, but at this time the pattern doesn`t seem to favor any large areas of dense fog. Therefore, generic fog wording was added to the grids overnight. Lows will be mild for another consecutive night - around 56 at TLH (compared with a normal low of 43). && .SHORT TERM [Saturday Through Monday]... The current, mainly zonal 500 mb pattern will become much more amplified by Monday, with a trough approaching our forecast area over the central CONUS. Until then, there is excellent agreement among the different sets of MOS in a continuation of above-average temperatures for our region, with highs in the mid to upper 70s inland (around 70 at the beaches), and lows in the mid to upper 50s inland (around 60 at the beaches). The only reason we won`t forecast even warmer high temperatures is because of the potential for fog and low clouds to linger into the early afternoon hours in some areas. We did make a slight change to our previous forecast for Saturday, as it now appears there will be at least a 20-30% chance of showers, especially in our western zones. The forcing for this is subtle, but it will apparently come from a combination of a weak 500 mb short wave translating rapidly eastward, a surface ridge axis termination zone, and just boundary layer moisture and instability to support moist convection. The latest Convection Allowing Models are quite bullish of this rain, though they have been known to over-forecast rain somewhat in this type of synoptic pattern. Still, the fact that we`ve already observed scattered showers over our Gulf coastal waters today indicates that, at least over the water, the thermodynamics could support shallow moist convection. Otherwise, rain chances will hold off until Monday, when an approaching cold front will help trigger scattered showers. The PoP will range from 50% just northwest of our forecast area, to 20% in Valdosta and Cross City. && .LONG TERM [Monday Night through Friday]... The extended period will begin with a broad, but amplifying, trough encompassing the entire country. Embedded within the large scale trough will be several shortwaves. More notably for the local area will be the disturbance positioned over the Four Corners region Sunday night. It will move across the Gulf Coast states through Monday, before exiting the Mid-Atlantic coast on Tuesday morning. At about the same time, another disturbance will also position itself over the Four Corners region before taking a similar path across the Gulf Coast states through the remainder of next week. At the surface, the effect from all of this will be a weakening surface ridge on Monday, being replaced with an approaching cold front likely to pass through the local area some time Monday night through Tuesday morning. There is much less confidence in the forecast for the remainder of the week, related to the second disturbance mentioned above. However, it will likely result in a gloomy mid to late week next week, with a possibility of disturbed weather through Friday. Overall, this pattern will be a welcomed change, bringing a chance for rain several days in the extended period. Additionally, the abnormal heat will come to an end in the wake of the first system, likely bringing temps back down to seasonal levels. && .AVIATION [through 18z Saturday]... Stratus has eroded across most of the area as of 20z, except around the DHN and ECP terminals. We expect a period of VFR late this afternoon and in the early evening at most, if not all, terminals. After that, the forecast becomes a bit tricky with signals from the model guidance rather inconsistent. Given that, we generally trended all of the terminals down into the MVFR range later tonight. && .MARINE... Winds and seas have been a bit higher than expected so far today, as the pressure gradient appears to have tighten locally near the trough south of the FL Panhandle. All of the NWP guidance, including the few high resolution models that initialized the stronger winds the best, insist that winds will quickly subside this evening, and remain quite low through this weekend. && .FIRE WEATHER... RH will remain above 35% through at least Tuesday, with increasing rain chances on Monday and Tuesday, so the fire weather concerns are minimal for the next four days. && .HYDROLOGY... River stages continued to be well below action stage, and this is likely to continue through at least the weekend. && .PRELIMINARY POINT TEMPS/POPS... Tallahassee 56 77 54 78 57 / 0 10 10 10 10 Panama City 61 74 60 75 62 / 10 20 10 10 10 Dothan 57 76 56 76 60 / 10 30 10 10 10 Albany 53 78 55 78 58 / 10 20 10 10 10 Valdosta 54 77 56 78 57 / 0 20 10 10 10 Cross City 55 78 54 80 56 / 0 20 10 10 10 Apalachicola 61 71 60 72 61 / 10 10 10 10 10 && .TAE WATCHES/WARNINGS/ADVISORIES... FL...None. GA...None. AL...None. GM...None. && $$ NEAR TERM/AVIATION/FIRE WX...Lamers SHORT TERM/HYDROLOGY...Fournier LONG TERM...Harrigan
AREA FORECAST DISCUSSION
NWS COLUMBIA SC
1018 PM EST SAT DEC 8 2012 .SYNOPSIS... WEAK SURFACE HIGH PRESSURE WILL REMAIN OVER THE REGION TONIGHT AND SUNDAY. A COLD FRONT WILL SLOWLY COME THROUGH MONDAY NIGHT AND TUESDAY...STALLING JUST TO OUR SOUTH THROUGH THURSDAY. && .NEAR TERM /THROUGH SUNDAY/... WEAK SURFACE HIGH PRESSURE THAT HAS BEEN OVER THE REGION IS BEGINNING TO GRADUALLY PUSH OFFSHORE. MODEL TIME SECTIONS INDICATE A LIGHT SOUTH/SOUTH-SOUTHWEST FLOW OVERNIGHT...WITH INCREASING LOW LEVEL MOISTURE TOWARD SUNDAY MORNING. SATELLITE LOOP/OBS SHOW SOME LOW CLOUDS ACROSS THE UPSTATE/GA WITH CIRRUS STREAMING OVERHEAD. AMOUNT OF CLOUD COVER STILL A BIT UNCERTAIN OVERNIGHT INTO SUNDAY...BUT EXPECT SOME OF THE LOW/MID CLOUDS ACROSS GA TO EVENTUALLY PUSH NORTH/NORTHEAST TO THE CSRA AND EVENTUALLY INTO THE MIDLANDS. AS FOR FOG POTENTIAL...WITH SOME AREAS MOSTLY CLEAR...EXPECT SOME PATCHY/AREAS OF FOG TO FORM AFTER MIDNIGHT AND LINGER THROUGH THE EARLY MORNING HOURS ON SUNDAY. && .SHORT TERM /SUNDAY NIGHT/... WEAK HIGH PRESSURE TO SHIFT TO THE EAST SOME SUNDAY AHEAD OF AN APPROACHING FRONT. A SW LOW TO MID LEVEL FLOW TO PROVIDE WARM TEMPS. MODELS OUTPUT SUGGESTS A WEAK UPPER DISTURBANCE...ALONG WITH SOME LOW LEVEL MOISTURE FLUX AND WEAK INSTABILITY MAY PRODUCE A FEW SHOWERS. CONFIDENCE LIMITED...BUT USED A MOS BLEND TO INDICATE A SLIGHT CHANCE OF A SHOWER OVER PORTIONS OF THE FA. && .LONG TERM /MONDAY THROUGH SATURDAY/... MODELS CONTINUE TREND OF SLOWING DOWN THE APPROACH OF THE NEXT FRONTAL BOUNDARY...NOW PROGGED TO SLOWLY COME THROUGH MONDAY NIGHT AND TUESDAY. MAINTAINED MENTION OF CHANCE SHOWERS...WITH SLIGHT CHANCE THUNDER...LATE MONDAY INTO TUE. WITH A SW FLOW ALOFT...PARALLEL TO THE FRONT...THE FRONT WILL BE SLOW TO MOVE THROUGH...AND GFS/ECMWF SUGGEST IT WILL STALL JUST SOUTH OF OUR REGION. CONTINUED TO ACCEPT HPC GUIDANCE...WHICH PREFERS ECMWF SOLUTION. ECMWF INDICATES ANOTHER WAVE TO MOVE ALONG THE FRONT LATE WED AND THU. && .AVIATION /03Z SUNDAY THROUGH THURSDAY/... DECREASING MID LEVEL CLOUDS THIS EVENING. WATER VAPOR INDICATING ANOTHER SHORT WAVE TO CROSS THE REGION OVERNIGHT...KEEPING HIGH CLOUDS IN THE AREA TO INHIBIT FOG DEVELOPMENT. AT THE SAME TIME FOG AND STRATUS OVER NORTHERN FL AND SOUTHERN GA MAKING SOME PROGRESS NORTHWARD. BOTH NAM AND RAP MODELS BRING FOG/STRATUS INTO THE SAVANNAH RIVER AREA 06Z-09Z AND CONTINUES TO SPREAD LIFR CONDITIONS ACROSS ALL TAF SITES. CONFIDENCE IS IMPROVING FOR IFR OR LOWER CONDITIONS OVERSPREADING THE TAF SITES OVERNIGHT INTO SUNDAY MORNING. SHOULD SEE IMPROVING CONDITIONS TO VFR 16Z-20Z. EXTENDED AVIATION OUTLOOK...HIGH LOW-LEVEL MOISTURE IS FORECAST TO RESULT IN WIDESPREAD IFR/LIFR CONDITIONS SUNDAY NIGHT INTO LATE MONDAY MORNING. FURTHER RESTRICTIONS POSSIBLE IN SHOWERS ASSOCIATED WITH A COLD FRONT MONDAY INTO WEDNESDAY. && .CAE WATCHES/WARNINGS/ADVISORIES... SC...NONE. GA...NONE. && $$
AREA FORECAST DISCUSSION
NWS COLUMBIA SC
931 PM EST SAT DEC 8 2012 .SYNOPSIS... WEAK SURFACE HIGH PRESSURE WILL REMAIN OVER THE REGION TONIGHT AND SUNDAY. A COLD FRONT WILL SLOWLY COME THROUGH MONDAY NIGHT AND TUESDAY...STALLING JUST TO OUR SOUTH THROUGH THURSDAY. && .NEAR TERM /THROUGH SUNDAY/... WEAK SURFACE HIGH PRESSURE THAT HAS BEEN OVER THE REGION IS BEGINNING TO GRADUALLY PUSH OFFSHORE. MODEL TIME SECTIONS INDICATE A LIGHT SOUTH/SOUTH-SOUTHWEST FLOW OVERNIGHT...WITH INCREASING LOW LEVEL MOISTURE TOWARD SUNDAY MORNING. SATELLITE LOOP/OBS SHOW SOME LOW CLOUDS ACROSS THE UPSTATE/GA WITH CIRRUS STREAMING OVERHEAD. AMOUNT OF CLOUD COVER STILL A BIT UNCERTAIN OVERNIGHT INTO SUNDAY...BUT EXPECT SOME OF THE LOW/MID CLOUDS ACROSS GA TO EVENTUALLY PUSH NORTH/NORTHEAST TO THE CSRA AND EVENTUALLY INTO THE MIDLANDS. AS FOR FOG POTENTIAL...WITH SOME AREAS MOSTLY CLEAR...EXPECT SOME PATCHY/AREAS OF FOG TO FORM AFTER MIDNIGHT AND LINGER THROUGH THE EARLY MORNING HOURS ON SUNDAY. && .SHORT TERM /SUNDAY NIGHT/... WEAK HIGH PRESSURE TO SHIFT TO THE EAST SOME SUNDAY AHEAD OF AN APPROACHING FRONT. A SW LOW TO MID LEVEL FLOW TO PROVIDE WARM TEMPS. MODELS OUTPUT SUGGESTS A WEAK UPPER DISTURBANCE...ALONG WITH SOME LOW LEVEL MOISTURE FLUX AND WEAK INSTABILITY MAY PRODUCE A FEW SHOWERS. CONFIDENCE LIMITED...BUT USED A MOS BLEND TO INDICATE A SLIGHT CHANCE OF A SHOWER OVER PORTIONS OF THE FA. && .LONG TERM /MONDAY THROUGH SATURDAY/... MODELS CONTINUE TREND OF SLOWING DOWN THE APPROACH OF THE NEXT FRONTAL BOUNDARY...NOW PROGGED TO SLOWLY COME THROUGH MONDAY NIGHT AND TUESDAY. MAINTAINED MENTION OF CHANCE SHOWERS...WITH SLIGHT CHANCE THUNDER...LATE MONDAY INTO TUE. WITH A SW FLOW ALOFT...PARALLEL TO THE FRONT...THE FRONT WILL BE SLOW TO MOVE THROUGH...AND GFS/ECMWF SUGGEST IT WILL STALL JUST SOUTH OF OUR REGION. CONTINUED TO ACCEPT HPC GUIDANCE...WHICH PREFERS ECMWF SOLUTION. ECMWF INDICATES ANOTHER WAVE TO MOVE ALONG THE FRONT LATE WED AND THU. && .AVIATION /02Z SUNDAY THROUGH THURSDAY/... PLENTY OF MID-LEVEL CLOUDS AFFECTING THE TAF SITES WITH LIGHT WINDS THIS EVENING. WATER VAPOR APPEARS TO KEEP MID/UPPER LEVEL MOISTURE ACROSS THE REGION THROUGH 06Z...PRECLUDING FOG DEVELOPMENT. MAY SEE ENOUGH DRYING ALOFT FOR RADIATIONAL COOLING AFTER 06Z. BOTH NAM AND RAP BUFKIT DEPICTS MORE STRATUS DEVELOPMENT THAN FOG BETWEEN 06Z AND 09Z. HIGH CONFIDENCE THAT AT LEAST MVFR VISIBILITY CONDITIONS WILL DEVELOP AFTER 06Z...WITH IFR OR LIFR VISIBILITY AND CEILINGS FROM THE 10Z TO 14Z PERIOD AT ALL TERMINAL LOCATIONS. IMPROVING CONDITIONS TO VFR 15Z-17Z. EXTENDED AVIATION OUTLOOK...HIGH LOW-LEVEL MOISTURE MAY RESULT IN WIDESPREAD IFR CONDITIONS MAINLY DURING THE EARLY MORNING MONDAY. FURTHER RESTRICTIONS POSSIBLE IN SHOWERS ASSOCIATED WITH A COLD FRONT MONDAY INTO WEDNESDAY. && .CAE WATCHES/WARNINGS/ADVISORIES... SC...NONE. GA...NONE. && $$ 77
AREA FORECAST DISCUSSION
NWS COLUMBIA SC
648 PM EST SAT DEC 8 2012 .SYNOPSIS... WEAK SURFACE HIGH PRESSURE WILL REMAIN OVER THE REGION TONIGHT AND SUNDAY. A COLD FRONT WILL SLOWLY COME THROUGH MONDAY NIGHT AND TUESDAY...STALLING JUST TO OUR SOUTH THROUGH THURSDAY. && .NEAR TERM /THROUGH SUNDAY/... WEAK SURFACE HIGH PRESSURE CURRENTLY OVER THE REGION. PLENTIFUL LOW LEVEL MOISTURE AND A WEAK UPPER DISTURBANCE PROVIDING SCT TO BKN CLOUDS. STILL UNCERTAIN ABOUT AMOUNT OF CLOUD COVER OVERNIGHT...BUT AS MENTIONED PLENTY OF LOW LEVEL MOISTURE ALONG WITH SOME WEAK ISENTROPIC LIFT OVERNIGHT. ANY CLEARING WOULD PROVIDE POTENTIAL FOR FOG DEVELOPMENT. SO EXPECT A COMBINATION OF MOSTLY CLOUDY SKIES AND PATCHY/AREAS OF FOG AFTER MIDNIGHT THROUGH SUNDAY MORNING. && .SHORT TERM /SUNDAY NIGHT/... WEAK HIGH PRESSURE TO SHIFT TO THE EAST SOME SUNDAY AHEAD OF AN APPROACHING FRONT. A SW LOW TO MID LEVEL FLOW TO PROVIDE WARM TEMPS. MODELS OUTPUT SUGGESTS A WEAK UPPER DISTURBANCE...ALONG WITH SOME LOW LEVEL MOISTURE FLUX AND WEAK INSTABILITY MAY PRODUCE A FEW SHOWERS. CONFIDENCE LIMITED...BUT USED A MOS BLEND TO INDICATE A SLIGHT CHANCE OF A SHOWER OVER PORTIONS OF THE FA. && .LONG TERM /MONDAY THROUGH SATURDAY/... MODELS CONTINUE TREND OF SLOWING DOWN THE APPROACH OF THE NEXT FRONTAL BOUNDARY...NOW PROGGED TO SLOWLY COME THROUGH MONDAY NIGHT AND TUESDAY. MAINTAINED MENTION OF CHANCE SHOWERS...WITH SLIGHT CHANCE THUNDER...LATE MONDAY INTO TUE. WITH A SW FLOW ALOFT...PARALLEL TO THE FRONT...THE FRONT WILL BE SLOW TO MOVE THROUGH...AND GFS/ECMWF SUGGEST IT WILL STALL JUST SOUTH OF OUR REGION. CONTINUED TO ACCEPT HPC GUIDANCE...WHICH PREFERS ECMWF SOLUTION. ECMWF INDICATES ANOTHER WAVE TO MOVE ALONG THE FRONT LATE WED AND THU. && .AVIATION /00Z SUNDAY THROUGH THURSDAY/... PLENTY OF MID-LEVEL CLOUDS AFFECTING THE TAF SITES WITH LIGHT WINDS THIS EVENING. WATER VAPOR APPEARS TO KEEP MID/UPPER LEVEL MOISTURE ACROSS THE REGION THROUGH 06Z...PRECLUDING FOG DEVELOPMENT. MAY SEE ENOUGH DRYING ALOFT FOR RADIATIONAL COOLING AFTER 06Z. BOTH NAM AND RAP BUFKIT DEPICTS MORE STRATUS DEVELOPMENT THAN FOG BETWEEN 06Z AND 09Z. HIGH CONFIDENCE THAT AT LEAST MVFR VISIBILITY CONDITIONS WILL DEVELOP AFTER 06Z...WITH IFR OR LIFR VISIBILITY AND CEILINGS FROM THE 10Z TO 14Z PERIOD AT ALL TERMINAL LOCATIONS. IMPROVING CONDITIONS TO VFR 15Z-17Z. EXTENDED AVIATION OUTLOOK...HIGH LOW-LEVEL MOISTURE MAY RESULT IN WIDESPREAD IFR CONDITIONS MAINLY DURING THE EARLY MORNING MONDAY. FURTHER RESTRICTIONS POSSIBLE IN SHOWERS ASSOCIATED WITH A COLD FRONT MONDAY INTO WEDNESDAY. && .CAE WATCHES/WARNINGS/ADVISORIES... SC...NONE. GA...NONE. && $$
AREA FORECAST DISCUSSION
NWS DES MOINES IA
904 PM CST SAT DEC 8 2012 .UPDATE... NO BIG CHANGES WITH EVENING UPDATE BUT HAVE NUDGED UP THE SNOW AMOUNTS NE IN THE MASON CITY AND WATERLOO AREAS. SMALL AREA OF PRECIP THAT MOVED THROUGH CENTRAL IA RECENTLY WAS MAINLY RAIN AT THE AIRPORT...BUT PRIMARILY SNOW JUST TO THE NORTH HERE AT THE OFFICE...AT BOONE AND AMES. MAINLY MELTED BUT JUST STUCK A LITTLE IN SOME AREAS. EXPECT THIS TO CONTINUE AS IT WORKS NE LATER TONIGHT AS 02Z RAP 2.5KM LAYER MAX WET BULB TEMP CHANGES LITTLE OVERNIGHT. THIS SUGGESTS CURRENT SNOW AND RAIN/SNOW LINES ARE A TAD TOO FAR NORTH AND HAVE SHIFTED THEM A BIT SOUTHWARD RESULTING IN A HALF INCH OR MORE INCREASE IN SNOW AMOUNTS THERE. LATEST NAM...DEV HRRR AND WRF RUNS ALL SUGGEST LOBE OF FORCING CURRENTLY PRODUCING PRECIP FROM SW MN INTO IA WILL FURTHER SATURATE AND THEN PHASE WITH MATURING SERN IA PRECIP WITH MORE WIDESPREAD COVERAGE OVER NERN IA TOWARD DAYBREAK. && .SHORT TERM /TONIGHT/... BAND OF STRONG THETA-E ADVECTION IS MOVING INTO WESTERN IOWA THIS AFTERNOON AND WILL CONTINUE TO MOVE ACROSS THE STATE THIS EVENING. RADAR ECHOES HAVE BEEN INTENSIFYING WITH THIS MID LEVEL FORCING FROM SOUTHWEST IOWA THROUGH SOUTHEAST SOUTH DAKOTA AND AT THIS TIME...ONLY PRECIPITATION REPORTS ARE FROM THE NORTHERN EDGE WITH CLOUD HEIGHTS REMAINING AOA 7KFT FARTHER SOUTH. EXPECT SOME LIGHT PRECIPITATION TO FALL OVER THE NORTHWEST THIRD TO HALF THIS EVENING ALONG THE INITIAL MOISTURE SURGE. SOME OF THIS PRECIPITATION COULD BE LIGHT SNOW GIVEN WETBULB PROFILES AS FAR SOUTH AS HIGHWAY 30 THOUGH NO ACCUMULATIONS ARE EXPECTED THIS EVENING EXCEPT FOR POSSIBLY THE FAR NORTH. A SECONDARY THETA-E SURGE WILL FOLLOW AFTER MIDNIGHT. THIS WILL HELP KEEP LOW LEVEL TEMPERATURES ABOVE FREEZING OVER THE CENTRAL AND SOUTH AND KEEP WETBULBS IN THE LOWEST 1500-2500FT 34F OR HIGHER. THIS LAYER WILL BE ENOUGH TO MELT ANY SNOW THROUGH THIS REGION. COLDER PROFILES YET NORTH WHERE PRECIPITATION WILL BE EXPANDING WITH THE ARRIVAL OF INCREASING KINEMATICS WITH THE APPROACH OF THE UPPER LEVEL SHORT WAVE. THE PRECIPITATION WILL BE ALL SNOW OVER THE NORTH. EXPECT SEASONAL TO SLIGHTLY HIGHER SNOW RATIOS OVER THE NORTH OF 13-15 TO 1 AND COULD HAVE ACCUMULATIONS BY 12Z OF 0.5 TO 1.5 INCHES ALONG AND NORTH OF A DENISON TO FORT DODGE TO WAVERLY LINE. NON-DIURNAL TEMPERATURE TRENDS OVERNIGHT WITH HIGHER DEWPOINTS MOVING INTO THE STATE. .LONG TERM /SUNDAY THROUGH FRIDAY/... THERE ARE TWO SYSTEMS TO FOCUS ON IN THE EXTENDED. THE FIRST IS THE SYSTEM FROM TONIGHT THAT WILL BE QUICKLY PUSHING ACROSS THE CWA DURING THE MORNING HOURS FOLLOWED BY STRONG COLD ADVECTION. SOUNDINGS AT 12Z SHOW TEMPERATURES AT OR JUST ABOVE FREEZING ACROSS THE FORECAST AREA. A COLD FRONT WILL SWEEP THE CWA THROUGH THE MORNING AND SOUNDING LOCATIONS WEST OF I-35 DRY OUT BEHIND THE FRONT WITH TEMPERATURES FALLING THROUGHOUT THE LATE MORNING AND THE REST OF THE DAY. FORCING WEAKENS THROUGHOUT THE DAY BUT POCKETS OF BETTER FORCING REMAIN ACROSS CENTRAL IOWA THROUGH MOST OF THE DAY. THE PROBLEM IS THAT WE LOSE OUR DEEPER MOISTURE QUICKLY IN THE MORNING. AS A RESULT...I AM NOT LOOKING FOR MUCH IN THE WAY OF PRECIPITATION/SNOW ACCUMULATION OUT OF THIS SYSTEM. WE COULD SEE A COUPLE OF INCHES ACROSS THE NORTH AT BEST WITH TRACE AMOUNTS ELSEWHERE AS PRECIP TRANSITIONS TO SNOW BEFORE ENDING. THE SURFACE LOW IS TOO FAR NORTH AND THE UPPER WAVE IS NOT DEEP ENOUGH TO DO MUCH MORE THAN THAT. WINDS ON THE OTHER HAND MAY BE PROBLEMATIC SUNDAY...ESPECIALLY COMBINED WITH THE COLD AIR MOVING IN. WIND CHILLS WILL FALL INTO THE TEENS DURING THE AFTERNOON. TUESDAY THROUGH THURSDAY...THERE WILL BE A LONG WAVE TROUGH PASSING ACROSS THE REGION WITH A RIDGE BUILDING INTO THE WEST TUESDAY AND SHIFTING ACROSS THE MIDWEST THROUGH THURSDAY AS A LARGE TROUGH CARVES OUT OVER THE WEST. THIS WILL BE A PLAYER IN OUR WEATHER INTO THE WEEKEND. THEN LATER IN THE WEEK...IN THE FRIDAY TO SATURDAY NIGHT TIME FRAME A SECOND POTENTIALLY STRONG SYSTEM WILL AFFECT CENTRAL IOWA. THERE ARE SIGNIFICANT DIFFERENCES BETWEEN THE MODELS...AT LEAST INITIALLY AS TO THE EVOLUTION OF THE UPPER LEVEL WAVE...THE SURFACE LOW AND THE FRONTAL BOUNDARY WITH THE SYSTEM. THE GFS LEAVES THIS AN OPEN WAVE THROUGH FRIDAY THEN DEVELOPS A LOW OVER SOUTH DAKOTA AS THE SYSTEM WRAPS UP WHILE THE EURO DEVELOPS A DEEP LOW OVER KANSAS AND LIFTS IT NORTHEAST. BOTH MODELS PUT THE UPPER LOW OVER SE MN AT 00Z BUT HOW IT GETS THERE IS AN QUESTION. THE EURO DEVELOPS A MUCH BETTER DEFORMATION ZONE OVER NORTHERN INTO WEST CENTRAL IOWA WHILE THE GFS HAS THIS FURTHER NORTH. THE SURFACE LOW POSITION IS ALSO QUITE DIFFERENT IN PLACEMENT AND INTENSITY. BOTH MODELS POINT AT SOUTHERN IOWA AND LOCATIONS SOUTH AND EAST BEING IN A WARM ADVECTION ZONE WITH PRETTY IMPRESSIVE CAPE FOR MID DECEMBER. THEREFORE I HAD TO PUT IN ISOLATED THUNDER ACROSS THE SOUTH. PTYPE ELSEWHERE IS VERY DIFFICULT TO PINPOINT AT THIS POINT. THE NORTH INTO WEST CENTRAL COULD HAVE A MIXED BAG OF PRECIP CHANGING TO SNOW AND ACCUMULATING. A RAIN/SNOW TRANSITION WILL OCCUR BETWEEN THERE AND SOUTH BUT THERE IS NOT ENOUGH AGREEMENT BETWEEN THE MODELS TO SAY WITH ANY CERTAINTY. AT THIS POINT IT LOOKS MESSY WITH A POTENTIAL FOR SEVERAL PTYPES ACROSS IOWA AND THUNDER SOUTH. HOWEVER THE MODELS DID SOMETHING SIMILAR WITH THIS CURRENT SYSTEM AT THAT FAR OUT. && .AVIATION...09/00Z VFR CONDITIONS IN PLACE ACROSS TAF SITES AT 00Z AND ARE EXPECTED TO REMAIN THAT WAY INTO THE EVENING. PRECIP...MAINLY VIRGA...WILL TRAVERSE THE STATE THIS EVENING ALTHOUGH IT MAY REACH THE GROUND IN ISOLATED INSTANCES OF TRACE AMOUNTS. HOWEVER OVERNIGHT CONDITIONS ARE EXPECTED TO DETERIORATE QUICKLY DROPPING TO IFR AS MORE PRECIPITATION DEVELOPS. PRECIP WINDOW IS EXPECTED TO BE AROUND 6-7 HOURS ENDING AT ALL STIES BY MIDDAY. THIS WILL BE FOLLOWED BY WINDS BECOMING NW WITH GUSTS INTO THE 20S DURING THE AFTERNOON. && .DMX WATCHES/WARNINGS/ADVISORIES...NONE. && $$ SHORT TERM...DONAVON LONG TERM...FAB AVIATION...SMALL
AREA FORECAST DISCUSSION
NWS DES MOINES IA
1135 PM CST THU DEC 6 2012 ...UPDATED AVIATION DISCUSSION... .SHORT TERM /TONIGHT/... WEAK SHORTWAVE WILL CONTINUE TO PUSH EAST OF THE FORECAST AREA LATE THIS AFTERNOON INTO THE EARLY EVENING WHILE A SECOND SHORTWAVE WILL MOVE ACROSS SOUTHERN IOWA/NORTHERN MISSOURI THROUGH 09Z FRIDAY. WEAK BOUNDARY ASSOCIATED WITH THE FIRST SHORTWAVE LOOKS TO BE INTO NORTHERN MISSOURI AND FAR SOUTHEAST IOWA BY 00Z FRIDAY. SLIGHTLY BETTER FORCING WITH THE SECOND VORT MAX LOOKS TO BE CONFINED TO SOUTHEAST IOWA. THIS IS EVIDENT ALONG THE 295K TO 305K ISENTROPIC SURFACE WHICH COINCIDES TO THE WEAK THETA-E ADVECTION AOA 700MB. BUFR SOUNDINGS SATURATED ABOVE 700MB SO PRECIP WILL BE HIGH BASED THIS EVENING. THE HI-RES MODELS RUNS OF THE NMM/ARW WRF AND HRRR ARE IN GOOD AGREEMENT WITH SOME LIGHT PRECIP OVER THE SOUTH THROUGH 09Z FRIDAY AND INCREASED POPS TO LIKELIES THROUGH 06Z IN THIS AREA. THE WRF SIMULATED GOES-R PRODUCTS ARE DEPICTING A CLEAR SLOT MOVING INTO CENTRAL IOWA FROM WEST TO EAST LATE TONIGHT INTO THE OVERNIGHT HOURS AND SOMEWHAT AGREE THERE SHOULD BE A BRIEF PERIOD OF CLEAR SKIES B/T 03-09Z. HOWEVER...THE SIMULATED PRODUCTS DO NOT HAVE A GOOD HANDLE ON CURRENT SATELLITE TRENDS WRT TO HIGHER CLOUDS IN NORTHWEST IOWA. SO DID NOT GO COMPLETELY CLEAR IN THE NORTH WITH ANOTHER WAVE MOVING INTO NORTHERN IOWA FRIDAY. LEANED TOWARD THE COOLER NAM12 FOR LOWS TONIGHT IN NORTHERN IOWA AND THE NISH VALLEY...THEN CLOSER TO THE GFS ACROSS THE SOUTHEAST. .LONG TERM /FRIDAY THROUGH THURSDAY/... MORE WRINKLES FOR THE WEEKEND EVENT...THOUGH SOME CONSENSUS BEGINNING TO SHOW UP REGARDING PREFERRED SOLUTION AND FORECAST. FIRST OF ALL THE SYSTEM ON FRIDAY APPEARS TO BE GRAZING THE FAR NORTH WITH SOME LIGHT SNOW AS MORE OF THE FORCING IN THE PAST TWO RUNS WILL OCCUR OVER SOUTHERN MINNESOTA...WITH JUST SOME LIGHT PRECIPITATION REACHING THE FAR NORTHERN COUNTIES OF THE FORECAST AREA AS THE SYSTEM PASSES TO THE EAST. THIS WILL LIMIT ANY SNOWFALL ACCUMULATIONS TO AN INCH OR LESS WITH THE FIRST WAVE DROPPING EAST SOUTHEAST WITH TIME TOMORROW. ONE OF THE WRINKLES IN THE UPCOMING FORECAST HAS BEEN A SHIFT TO LESS COLD AIR ARRIVING IN THE NEXT 48 HOURS AHEAD OF THE LATE WEEKEND WAVES. THIS WILL MODERATE BOTH HIGHS AND LOWS...RESULTING IN A SLIGHTLY LONGER CHANGEOVER FROM LIQUID TO FROZEN PRECIPITATION ON SUNDAY. THIS IS MAINLY DUE TO THE LACK OF UPPER LEVEL ENERGY PHASING WHICH KEEPS THE NORTHERN STREAM SHORT WAVE STRONGER AND THE COLD AIR FROM DRIVING SOUTH BEHIND THE SYSTEM FAST ENOUGH TO INTERACT WITH THE SOUTHERN STREAM. THUS...WITH LITTLE COLD AIR ADVECTION IN THE OFFING UNTIL THE STORM PASSES TO THE EAST SUNDAY EVENING...THERE WILL BE LITTLE AMPLIFICATION OF THE ENTIRE SYSTEM AND LESSER AMOUNTS OF FORCING...QPF...AND SNOWFALL PRODUCTION OVER THE FORECAST AREA. NEVER THE LESS...SOME ACCUMULATION IS EXPECTED AS THE TIMING OVER THE NORTH FAVORS A QUICKER CHANGEOVER COMPARED TO THE SOUTH. WITH CONTINUED UNCERTAINTY IN BOTH TIMING AND AREAL COVERAGE OF PRECIPITATION OVER THE RANGE OF MODEL SOLUTIONS... HAVE OPTED TO LEAN TOWARD A MANUAL BLEND OF THE EURO/NAM/GEM WITH LESS EMPHASIS ON THE GFS WHICH HAS DONE A COMPLETE REVERSAL SINCE YESTERDAY. THE ONLY TREND IN THE MODELS NOW IS LITTLE TO NO PHASING OF THE NORTHERN AND SOUTHERN STREAMS AND SLIGHTLY WARMER TEMPS AS PREVIOUSLY MENTIONED. THUS...SOME LIGHT SNOW WITH A POTENTIAL FOR A BRIEF PERIOD OF HEAVIER RAIN OR SNOW SATURDAY NIGHT LATE NORTHEAST IS EXPECTED AS THE SYSTEM ROLLS ON THROUGH. SUNDAY FOR THE MOST PART WILL EXPERIENCE FALLING TEMPERATURES WITH LESS INTENSE PRECIPITATION. LIGHT ACCUMULATIONS OF SNOW WILL OCCUR BOTH SATURDAY NIGHT AND SUNDAY OVER THE FORECAST AREA AND AMOUNTS WILL RANGE FROM NEAR ONE HALF INCH IN THE SOUTH TO NEARLY 1.5 TO 2 INCHES IN THE NORTHEAST. THOUGH THE COLD AIR FINALLY ARRIVES BY SUNDAY NIGHT AND MONDAY...SOME MODERATION IS ALREADY EXPECTED TO OCCUR BY TUESDAY THROUGH THURSDAY WHEN HIGHS REACH THE 30S TO LOWER 40S OVER THE REGION SO WHAT SNOW DOES FALL THIS WEEKEND WILL SLOWLY DISAPPEAR TOWARD NEXT THURSDAY. LITTLE TO NO PRECIPITATION WILL OCCUR AFTER THE STORM SUNDAY...SO THE BALANCE OF THE EXTENDED FORECAST LOOKS DRY. && .AVIATION...07/06Z -RA ASSOCIATED WITH WEAK BOUNDARY WILL QUICKLY PUSH OUT OF KOTM...WITH VFR CEILINGS THROUGH PERIOD...THOUGH LOW VFR CEILINGS WILL PUSH IN TOWARDS END OF PERIOD. A WAVE PUSHING ACROSS THE NORTH WILL BRING PRECIPITATION CHANCES TO NORTHERN SITES KMCW/KALO LATE IN PERIOD...ALONG WITH POSSIBLE MVFR CEILINGS. HAVE NOT INCLUDED MENTION ATTM WITH UNCERTAINTIES. && .DMX WATCHES/WARNINGS/ADVISORIES...NONE. && $$ SHORT TERM...PODRAZIK LONG TERM...REV AVIATION...AWB
AREA FORECAST DISCUSSION
NWS WICHITA KS
926 PM CST SAT DEC 8 2012 .UPDATE... LOW CLOUDS AND DRIZZLE HAVE OVERSPREAD MUCH OF CENTRAL AND SOUTH CENTRAL KS THIS EVENING...AS ISENTROPIC LIFT CONTINUES IN THE 295-300K LAYER. THIS WEAK LIFT HAS LED TO SOME SATURATION IN THE LOWEST LAYERS OF THE ATMOSPHERE...WITH WIDESPREAD STRATUS BUILDING DOWN AS THE EVENING PROGRESSES WITH DRIZZLE AND SOME AREAS OF FOG. THIS DRIZZLE AND FOG WILL BE SHORT LIVED...ESPECIALLY ACROSS CENTRAL KS...AS A STRONG COLD FRONT PUSHES INTO CENTRAL KS BY AROUND 06Z/SUN AND KEEPS PUSHING SOUTH ACROSS THE REST OF THE REGION LATE TONIGHT OR EARLY ON SUN. THIS FRONT WILL SHIFT THE WINDS RAPIDLY AROUND TO THE NORTH AND BECOME GUSTY AT 20 TO 30 MPH. IT WILL ALSO HELP SCOUR OUT MOST OF THE LOW LEVEL MOISTURE IS IT PUSHES SOUTH...ENDING THE DRIZZLE AND FOG AS IT MOVES SOUTH. AS THIS FRONT APPROACHES...WITH A SHORTWAVE PUSHING ACROSS NEB. LIFT ASSOCIATED WITH THIS FRONT AND SHORTWAVE COULD LEAD TO SOME LIGHT RAIN ACROSS CEN KS. COULD SEE THIS LIGHT RAIN CHANCE POSSIBLY TURN OVER OR MIX WITH SOME LIGHT SNOW...AS COLDER AIR ALOFT MOVES ACROSS NEB BY EARLY ON SUN. BUT LACK OF DEEP MOISTURE WILL MAINLY LEAD TO VERY LIGHT PRECIPITATION...WITH MAINLY FLURRIES AS IT TURNS OVER TO SNOW. KETCHAM && .PREV DISCUSSION... /ISSUED 556 PM CST SAT DEC 8 2012/ AVIATION...00Z TAFS KRSL/KSLN/KHUT/KICT/KCNU LOW LEVEL ISENTROPIC LIFT FROM THE SOUTH-SOUTHWEST WILL LEAD TO DETERIORATING FLIGHT CONDITIONS THIS EVENING...AS WIDESPREAD MVFR CIGS/VSBYS AND AREAS OF IFR CIGS PUSH INTO THE AREA THROUGH THE EVENING HOURS. BOTH THE NAM/WRF AND GFS NOT HANDLING THIS LOWER CEILING TREND VERY WELL...WITH THE LATEST RUC40 CLOSER TO REALITY. EVEN WENT MORE PESSIMISTIC THAN THE RUC ON CEILINGS AND FOG. A COLD FRONTAL BOUNDARY LOOKS TO ARRIVE AFTER 06Z/SUN ACROSS CENTRAL KANSAS...AND FURTHER SOUTH ACROSS SOUTH CENTRAL KS AFTER 09-10Z/SUN. THIS WILL LEAD TO CEILINGS BEGINNING TO LIFT WITH MVFR/VFR CEILINGS FOR THE MORNING HOURS ON SUN. WINDS BEHIND THE FRONT WILL INCREASE TO 20-30 KTS WITH SOME LIGHT SNOW DEVELOPING ACROSS PORTIONS OF CENTRAL KANSAS ON SUNDAY. NOT EXPECTING THE LIGHT SNOW TO RESTRICT VSBYS MUCH...AS THIS WILL BE MAINLY A LIGHT SNOW EVENT/FLURRY EVENT. KETCHAM PREV DISCUSSION... /ISSUED 311 PM CST SAT DEC 8 2012/ DISCUSSION... MAIN FORECAST CONCERNS ARE PRECIP CHANCES AND TYPE TONIGHT THROUGH SUN ALONG WITH HOW COLD TO GO FOR SUN-MON. SYNOPSIS: STRONG SHORTWAVE IS DIVING OVER THE NORTHERN ROCKIES AND APPROACHING THE NORTHERN HIGH PLAINS. AT THE SURFACE...TROUGHING EXTENDS FROM SW SD INTO EASTERN CO. THIS HAS LEFT WARM MOIST FLOW OVER THE SOUTHERN AND CENTRAL PLAINS WHICH HAS ALLOWED LOW CLOUDS TO MOVE BACK IN ACROSS MUCH OF THE FORECAST AREA. TONIGHT-SUN NIGHT: WITH THE LOW LEVEL WARM MOIST FLOW REMAINING IN PLACE...THINKING THAT THE LOW CLOUDS WILL MAINTAIN AND WILL LIKELY LOWER A BIT THIS EVENING. IN ADDITION ALSO FEEL THAT AFTER DARK SOME LIGHT FOG AND DRIZZLE WILL ACCOMPANY THE LOW CIGS. MID LEVEL LIFT WILL COMMENCE OVER CENTRAL AND NORTHEAST KS THIS EVENING WHICH SHOULD RESULT IN SOME LIGHT SHOWERS WITH SOME OF THESE SHOWERS TRANSITIONING TO SOME LIGHT SNOW AFTER AFTER 3 AM AS MUCH COLDER AIR STARTS TO SPILL-IN FROM THE NORTH. NOT EXPECTING ANYTHING IN THE WAY OF ACCUMULATION OVERNIGHT. JUST LIKE THE LAST FEW MODEL RUNS...THE MAIN PIECE OF ENERGY IS EXPECTED TO BREAK OFF INTO TWO PIECES. ONE WILL MOVE TOWARDS THE GREAT LAKES WHILE THE OTHER DIVES OVER THE DESERT SW AND EVENTUALLY THE SOUTHERN PLAINS. STILL THINKING THAT THE PRECIP ON SUN WILL PRIMARILY BE IN THE FORM OR FLURRIES AND SPRINKLES. THE EXCEPTION WOULD BE THE EAST AND NORTHEAST FRINGES OF THE FORECAST AREA WHERE THE DEEPER LIFT AND MOISTURE WILL BE SITUATED. EVEN THE LOCATIONS THAT DO SEEM SOME SNOW SHOWERS CAN EXPECT TO ONLY PICKUP VERY LIGHT AMOUNTS. THE MAIN STORY WITH THIS SYSTEM WILL CONTINUE TO BE THE COLDEST TEMPS OF THE SEASON SO FAR WITH SINGLE DIGITS A GOOD BET FOR MUCH OF CENTRAL KS MON MORNING. MON-SAT: THE LONGWAVE TROUGH IS EXPECTED TO POSITION ITSELF OVER THE CENTRAL CONUS TO START THE WORK WEEK AS ADDITIONAL UPPER IMPULSES DIVE DOWN THE BACKSIDE OF THE TROUGH AND ACROSS THE SOUTHERN PLAINS FOR MON NIGHT INTO TUE. THIS PATTERN WILL RESULT IN A CONTINUATION OF BELOW NORMAL TEMPS WITH THE MOISTURE AND ASSOCIATED PRECIP CHANCES PUSHED WELL EAST OF THE FORECAST AREA. BY MID WEEK THE UPPER PATTERN WILL QUICKLY TRANSITION FROM NW FLOW ALOFT TO SW FLOW BY WED AFTERNOON AS OUR NEXT SHORTWAVE DIGS OVER THE WEST COAST. THIS WILL GET THE PLAINS BACK INTO A WARMING PATTERN THAT WILL CONTINUE FOR THU INTO FRI. THE SHORTWAVE WILL START TO DIRECTLY IMPACT THE AREA BY FRI INTO SAT. THE ECMWF IS MUCH MORE COMPACT THE MORE PROGRESSIVE WITH THIS WAVE COMPARED TO THE GFS. REGARDLESS OF WHICH ONE VERIFIES IT APPEARS THE BEST SNOW CHANCES WILL BE NORTH OF THE FORECAST AREA WITH SOME SHOWERS AND EVEN A FEW STORMS POSSIBLE FOR FRI...TRANSITIONING TO SOME LIGHT SNOW OR FLURRIES FOR FRI NIGHT. LAWSON && .PRELIMINARY POINT TEMPS/POPS... WICHITA-KICT 35 38 13 35 / 10 10 10 0 HUTCHINSON 34 35 12 36 / 10 10 10 0 NEWTON 34 37 12 35 / 10 20 10 0 ELDORADO 36 39 14 34 / 10 20 10 0 WINFIELD-KWLD 37 39 15 36 / 10 20 10 0 RUSSELL 28 32 6 39 / 20 10 10 0 GREAT BEND 31 33 7 38 / 10 10 10 0 SALINA 31 32 10 37 / 20 10 10 0 MCPHERSON 34 35 11 36 / 20 10 10 0 COFFEYVILLE 44 45 19 36 / 10 30 10 10 CHANUTE 42 43 18 34 / 10 30 10 10 IOLA 41 43 17 33 / 10 30 10 10 PARSONS-KPPF 43 44 18 35 / 10 30 10 10 && .ICT WATCHES/WARNINGS/ADVISORIES... NONE. && $$
AREA FORECAST DISCUSSION
NWS GOODLAND KS
802 PM MST SAT DEC 8 2012 .UPDATE... ISSUED AT 757 PM MST SAT DEC 8 2012 PER SATELLITE AND LATEST MODEL DATA INCREASED CLOUD COVER THROUGH TOMORROW MORNING. LOOKING AT CURRENT SURFACE OBSERVATION DATA AND CONSIDERING THE HIGHER WINDS/MORE CLOUD COVER...CHOSE TO RAISE MINS A LITTLE WHICH DOES FIT WITH SOME OF THE NEWER GUIDANCE. CURRENT PRECIPITATION FORECAST LOOKS FINE. WINDS WILL BEGIN GUSTING TO JUST UNDER WIND ADVISORY CRITERIA. IT LOOKS CLOSE FOR WIND ADVISORY AND WILL LET THE OVERNIGHT SHIFT ADDRESS THAT. GRIDS ARE ALREADY REFLECTING IT. UPDATE ISSUED AT 605 PM MST SAT DEC 8 2012 JUST COMPLETED AN UPDATE. FIRST FRONT IN A SERIES OF FRONTS ALREADY BLASTING THROUGH WHICH IS FASTER THAN ANY MODEL DEPICTION OR WHAT THE GRIDS HAD WHICH IS NOT UNCOMMON IN THIS SCENARIO. NOT ONLY IS THE FRONT THROUGH...BUT WIND SPEEDS ALREADY TO NEAR 40 MPH IN SOME LOCATIONS. RUC WAS THE FASTEST MODEL BUT WAS STILL A LITTLE SLOW AND UNDERDONE ON THE SPEEDS. SO USED IT AND MODIFIED WITH REALITY. HOPEFULLY NEWER MODEL DATA WILL CATCH UP WITH THIS. ALSO INCREASED SPEEDS FOR LATER TONIGHT AND TOMORROW AS WELL WITH WHAT LOOKS TO BE DECENT MIXING. CONSIDERING THE COLD AIR ADVECTION ALREADY OCCURRING...THERE MAY NOT BE ANY LOW LEVEL INVERSION TO OVERCOME AND WIND SPEEDS MAY BE EVEN HIGHER THAN WHAT I HAVE DEPICTED. WILL CONTINUE TO WATCH AND TWEAK AS NEWER DATA COMES IN. && .SHORT TERM...(THIS AFTERNOON THROUGH SUNDAY) ISSUED AT 1059 AM MST SAT DEC 8 2012 EXCEPT FOR THE COLD AIR MOVING IN BEHIND THE FRONT THIS EVENING AND OVERNIGHT...THIS EVENT IS BEGINNING TO LOOK MORE LIKE A NON- EVENT. HAVE TONED DOWN THE MENTION OF ANY ACCUMULATING SNOW AND HAVE PUT IN A MENTION OF SPRINKLES OR FLURRIES IN THE FAR NORTHWEST CORNER OF THE FORECAST AREA BEFORE 00Z WITH A MORE EXTENSIVE AREA OF FLURRIES ALONG AND BEHIND THE FRONT AS IT MOVES THROUGH THE FORECAST AREA TONIGHT. THE NAM CONTINUES TO BE DRY WITH THE ECMWF AND GFS ONLY PRODUCING AROUND ONE HUNDREDTH OF QPF ALONG THE NORTHERN AND WESTERN FRINGES OF THE FORECAST AREA. FLURRIES WILL DIMINISH EARLY SUNDAY WITH SKIES BEGINNING TO CLEAR BY LATE SUNDAY AFTERNOON AS SURFACE HIGH PRESSURE BEGINS TO MOVE INTO THE REGION. BECAUSE OF THE DECREASING CLOUDS COVER AND SLACKENING WINDS SUNDAY NIGHT...EXPECT THE COLDEST TEMPERATURES OF THE SEASON WITH LOWS DROPPING DOWN TO AROUND ZERO IN SOME LOCATIONS. WIND CHILL BELOW ZERO WILL BE COMMON. .LONG TERM...(SUNDAY NIGHT THROUGH SATURDAY) ISSUED AT 112 PM MST SAT DEC 8 2012 SUNDAY NIGHT THROUGH TUESDAY NIGHT THE BASE OF THE LONG WAVE TROUGH WILL REMAIN OVER THE AREA. SUNDAY NIGHT THE TROUGH AXIS...FROM THE SHORT WAVE TROUGH RESPONSIBLE FOR THE WINTER STORM OVER THE NORTHERN PLAINS...WILL MOVE THROUGH THE AREA. UNFORTUNATELY DRIER AIR WILL BE OVER THE AREA BY THE TIME THE TROUGH AXIS MOVES THROUGH AND THE LEFT ENTRANCE OF THE 500-300MB JET WILL BE OVER THE AREA AHEAD OF THE TROUGH AXIS...LEADING TO DRY CONDITIONS FOR THE AREA. WINDS WILL DECREASE DURING THE EVENING AS A SURFACE HIGH BUILDS INTO THE AREA. WITH LITTLE TO NO WIND AND CLEAR SKIES...TEMPERATURES WILL FALL TO THE SINGLE DIGITS. ANY WIND THAT DOES DEVELOP WILL PRODUCE WIND CHILL VALUES NEAR 15 BELOW ZERO. MONDAY SEVERAL WEAKER SHORT WAVE TROUGHS MOVE THROUGH...BUT THERE WILL BE LITTLE TO NO MOISTURE TO WORK WITH. DURING THE LATE AFTERNOON/EVENING AREA SOUNDINGS SATURATE AS MOISTURE MOVES INTO THE AREA BEHIND A SURFACE AND UPPER LEVEL TROUGH. HOWEVER THE INCREASED MOISTURE WILL BE IN THE SUBSIDENCE AREA BEHIND THE SHORT WAVE TROUGH. FOR THE TUESDAY THROUGH SATURDAY PERIOD...DRY CONDITIONS WILL CONTINUE TO PREVAIL. THE LONG WAVE TROUGH MOVES EAST TUESDAY ALLOWING A LONG WAVE RIDGE TO MOVE OVER THE CENTRAL PLAINS THROUGH THE MAJORITY OF NEXT WEEK. MEANWHILE THE NEXT SHORT WAVE TROUGH MOVES ONSHORE WEDNESDAY...APPROACHING THE AREA FRIDAY. MODELS AGREE WITH THE TRACK OF THE TROUGH...MOVING IT OVER THE TEXAS AND OKLAHOMA PANHANDLES. THE POSITION OF THE TROUGH IS STILL TOO FAR SOUTH FOR THE AREA TO RECEIVE ANY PRECIPITATION. HOWEVER THE MODELS HAVE TRENDED FURTHER NORTH WITH THE TROUGH SINCE YESTERDAY. FRIDAY NIGHT THE GEFS MEMBERS INDICATED A SLIGHT CHANCE FOR SOME PRECIPITATION OVER THE EASTERN PART OF THE AREA. GFS ISENTROPIC LIFT DOES SHOW SOME LIFT AND MOISTURE CO-LOCATED AROUND 600MB OVER THOSE LOCATIONS. IF THIS FEATURE IS STILL THERE TOMORROW...SLIGHT CHANCES MAY NEED TO BE ADDED FOR THE EAST FRIDAY NIGHT. TEMPERATURES WILL BE NEAR NORMAL...WITH A SMALL WARMING TREND THROUGH THE PERIOD. A COLD FRONT WILL MOVE THROUGH FRIDAY BEHIND THE UPPER LEVEL TROUGH...BUT THE COOLER AIR MASS BEHIND THE FRONT WILL QUICKLY MOVE EAST FOLLOWING THE UPPER LEVEL TROUGH. THIS WILL ALLOW TEMPERATURES FOR SATURDAY TO REMAIN LARGELY UNAFFECTED BY THE FRONTAL PASSAGE. && .AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SUNDAY EVENING) ISSUED AT 440 PM MST SAT DEC 8 2012 VFR CONDITIONS ARE EXPECTED THROUGH THE PERIOD. A SERIES OF COLD FRONTS WILL PUSH ACROSS THE AREA THROUGH THE MORNING HOURS. LITTLE LEVEL MOISTURE IS AVIALABLE FOR LIFT WITH SOME FLURRIES POSSIBLE AS THE INITIAL STRONG PUSHES ACROSS THE AREA DURING THE LATE TO MID EVENING HOURS. EXPECT THE FLURRIES AND ANY LOW CLOUDS...WHICH AM NOT EXPECTING A LOT OF AT THIS TIME...WILL PUSH THROUGH RAPIDLY AND WILL BE DONE BY 06Z OR 07Z. OTHERWISE...GUSTY NORTH TO NORTHWEST WINDS WILL BE IN PLACE FOR A MAJORITY OF THE PERIOD. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...NONE. CO...NONE. NE...NONE. && $$ UPDATE...BULLER SHORT TERM...LOCKHART LONG TERM...JTL AVIATION...BULLER
AREA FORECAST DISCUSSION
NWS GOODLAND KS
615 PM MST SAT DEC 8 2012 .UPDATE... ISSUED AT 605 PM MST SAT DEC 8 2012 JUST COMPLETED AN UPDATE. FIRST FRONT IN A SERIES OF FRONTS ALREADY BLASTING THROUGH WHICH IS FASTER THAN ANY MODEL DEPICTION OR WHAT THE GRIDS HAD WHICH IS NOT UNCOMMON IN THIS SCENARIO. NOT ONLY IS THE FRONT THROUGH...BUT WIND SPEEDS ALREADY TO NEAR 40 MPH IN SOME LOCATIONS. RUC WAS THE FASTEST MODEL BUT WAS STILL A LITTLE SLOW AND UNDERDONE ON THE SPEEDS. SO USED IT AND MODIFIED WITH REALITY. HOPEFULLY NEWER MODEL DATA WILL CATCH UP WITH THIS. ALSO INCREASED SPEEDS FOR LATER TONIGHT AND TOMORROW AS WELL WITH WHAT LOOKS TO BE DECENT MIXING. CONSIDERING THE COLD AIR ADVECTION ALREADY OCCURRING...THERE MAY NOT BE ANY LOW LEVEL INVERSION TO OVERCOME AND WIND SPEEDS MAY BE EVEN HIGHER THAN WHAT I HAVE DEPICTED. WILL CONTINUE TO WATCH AND TWEAK AS NEWER DATA COMES IN. && .SHORT TERM...(THIS AFTERNOON THROUGH SUNDAY) ISSUED AT 1059 AM MST SAT DEC 8 2012 EXCEPT FOR THE COLD AIR MOVING IN BEHIND THE FRONT THIS EVENING AND OVERNIGHT...THIS EVENT IS BEGINNING TO LOOK MORE LIKE A NON- EVENT. HAVE TONED DOWN THE MENTION OF ANY ACCUMULATING SNOW AND HAVE PUT IN A MENTION OF SPRINKLES OR FLURRIES IN THE FAR NORTHWEST CORNER OF THE FORECAST AREA BEFORE 00Z WITH A MORE EXTENSIVE AREA OF FLURRIES ALONG AND BEHIND THE FRONT AS IT MOVES THROUGH THE FORECAST AREA TONIGHT. THE NAM CONTINUES TO BE DRY WITH THE ECMWF AND GFS ONLY PRODUCING AROUND ONE HUNDREDTH OF QPF ALONG THE NORTHERN AND WESTERN FRINGES OF THE FORECAST AREA. FLURRIES WILL DIMINISH EARLY SUNDAY WITH SKIES BEGINNING TO CLEAR BY LATE SUNDAY AFTERNOON AS SURFACE HIGH PRESSURE BEGINS TO MOVE INTO THE REGION. BECAUSE OF THE DECREASING CLOUDS COVER AND SLACKENING WINDS SUNDAY NIGHT...EXPECT THE COLDEST TEMPERATURES OF THE SEASON WITH LOWS DROPPING DOWN TO AROUND ZERO IN SOME LOCATIONS. WIND CHILL BELOW ZERO WILL BE COMMON. .LONG TERM...(SUNDAY NIGHT THROUGH SATURDAY) ISSUED AT 112 PM MST SAT DEC 8 2012 SUNDAY NIGHT THROUGH TUESDAY NIGHT THE BASE OF THE LONG WAVE TROUGH WILL REMAIN OVER THE AREA. SUNDAY NIGHT THE TROUGH AXIS...FROM THE SHORT WAVE TROUGH RESPONSIBLE FOR THE WINTER STORM OVER THE NORTHERN PLAINS...WILL MOVE THROUGH THE AREA. UNFORTUNATELY DRIER AIR WILL BE OVER THE AREA BY THE TIME THE TROUGH AXIS MOVES THROUGH AND THE LEFT ENTRANCE OF THE 500-300MB JET WILL BE OVER THE AREA AHEAD OF THE TROUGH AXIS...LEADING TO DRY CONDITIONS FOR THE AREA. WINDS WILL DECREASE DURING THE EVENING AS A SURFACE HIGH BUILDS INTO THE AREA. WITH LITTLE TO NO WIND AND CLEAR SKIES...TEMPERATURES WILL FALL TO THE SINGLE DIGITS. ANY WIND THAT DOES DEVELOP WILL PRODUCE WIND CHILL VALUES NEAR 15 BELOW ZERO. MONDAY SEVERAL WEAKER SHORT WAVE TROUGHS MOVE THROUGH...BUT THERE WILL BE LITTLE TO NO MOISTURE TO WORK WITH. DURING THE LATE AFTERNOON/EVENING AREA SOUNDINGS SATURATE AS MOISTURE MOVES INTO THE AREA BEHIND A SURFACE AND UPPER LEVEL TROUGH. HOWEVER THE INCREASED MOISTURE WILL BE IN THE SUBSIDENCE AREA BEHIND THE SHORT WAVE TROUGH. FOR THE TUESDAY THROUGH SATURDAY PERIOD...DRY CONDITIONS WILL CONTINUE TO PREVAIL. THE LONG WAVE TROUGH MOVES EAST TUESDAY ALLOWING A LONG WAVE RIDGE TO MOVE OVER THE CENTRAL PLAINS THROUGH THE MAJORITY OF NEXT WEEK. MEANWHILE THE NEXT SHORT WAVE TROUGH MOVES ONSHORE WEDNESDAY...APPROACHING THE AREA FRIDAY. MODELS AGREE WITH THE TRACK OF THE TROUGH...MOVING IT OVER THE TEXAS AND OKLAHOMA PANHANDLES. THE POSITION OF THE TROUGH IS STILL TOO FAR SOUTH FOR THE AREA TO RECEIVE ANY PRECIPITATION. HOWEVER THE MODELS HAVE TRENDED FURTHER NORTH WITH THE TROUGH SINCE YESTERDAY. FRIDAY NIGHT THE GEFS MEMBERS INDICATED A SLIGHT CHANCE FOR SOME PRECIPITATION OVER THE EASTERN PART OF THE AREA. GFS ISENTROPIC LIFT DOES SHOW SOME LIFT AND MOISTURE CO-LOCATED AROUND 600MB OVER THOSE LOCATIONS. IF THIS FEATURE IS STILL THERE TOMORROW...SLIGHT CHANCES MAY NEED TO BE ADDED FOR THE EAST FRIDAY NIGHT. TEMPERATURES WILL BE NEAR NORMAL...WITH A SMALL WARMING TREND THROUGH THE PERIOD. A COLD FRONT WILL MOVE THROUGH FRIDAY BEHIND THE UPPER LEVEL TROUGH...BUT THE COOLER AIR MASS BEHIND THE FRONT WILL QUICKLY MOVE EAST FOLLOWING THE UPPER LEVEL TROUGH. THIS WILL ALLOW TEMPERATURES FOR SATURDAY TO REMAIN LARGELY UNAFFECTED BY THE FRONTAL PASSAGE. && .AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SUNDAY EVENING) ISSUED AT 440 PM MST SAT DEC 8 2012 VFR CONDITIONS ARE EXPECTED THROUGH THE PERIOD. A SERIES OF COLD FRONTS WILL PUSH ACROSS THE AREA THROUGH THE MORNING HOURS. LITTLE LEVEL MOISTURE IS AVIALABLE FOR LIFT WITH SOME FLURRIES POSSIBLE AS THE INITIAL STRONG PUSHES ACROSS THE AREA DURING THE LATE TO MID EVENING HOURS. EXPECT THE FLURRIES AND ANY LOW CLOUDS...WHICH AM NOT EXPECTING A LOT OF AT THIS TIME...WILL PUSH THROUGH RAPIDLY AND WILL BE DONE BY 06Z OR 07Z. OTHERWISE...GUSTY NORTH TO NORTHWEST WINDS WILL BE IN PLACE FOR A MAJORITY OF THE PERIOD. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...NONE. CO...NONE. NE...NONE. && $$ UPDATE...BULLER SHORT TERM...LOCKHART LONG TERM...JTL AVIATION...BULLER
AREA FORECAST DISCUSSION
NWS WICHITA KS
556 PM CST SAT DEC 8 2012 .AVIATION...00Z TAFS KRSL/KSLN/KHUT/KICT/KCNU LOW LEVEL ISENTROPIC LIFT FROM THE SOUTH-SOUTHWEST WILL LEAD TO DETERIORATING FLIGHT CONDITIONS THIS EVENING...AS WIDESPREAD MVFR CIGS/VSBYS AND AREAS OF IFR CIGS PUSH INTO THE AREA THROUGH THE EVENING HOURS. BOTH THE NAM/WRF AND GFS NOT HANDLING THIS LOWER CEILING TREND VERY WELL...WITH THE LATEST RUC40 CLOSER TO REALITY. EVEN WENT MORE PESSIMISTIC THAN THE RUC ON CEILINGS AND FOG. A COLD FRONTAL BOUNDARY LOOKS TO ARRIVE AFTER 06Z/SUN ACROSS CENTRAL KANSAS...AND FURTHER SOUTH ACROSS SOUTH CENTRAL KS AFTER 09-10Z/SUN. THIS WILL LEAD TO CEILINGS BEGINNING TO LIFT WITH MVFR/VFR CEILINGS FOR THE MORNING HOURS ON SUN. WINDS BEHIND THE FRONT WILL INCREASE TO 20-30 KTS WITH SOME LIGHT SNOW DEVELOPING ACROSS PORTIONS OF CENTRAL KANSAS ON SUNDAY. NOT EXPECTING THE LIGHT SNOW TO RESTRICT VSBYS MUCH...AS THIS WILL BE MAINLY A LIGHT SNOW EVENT/FLURRY EVENT. KETCHAM && .PREV DISCUSSION... /ISSUED 311 PM CST SAT DEC 8 2012/ DISCUSSION... MAIN FORECAST CONCERNS ARE PRECIP CHANCES AND TYPE TONIGHT THROUGH SUN ALONG WITH HOW COLD TO GO FOR SUN-MON. SYNOPSIS: STRONG SHORTWAVE IS DIVING OVER THE NORTHERN ROCKIES AND APPROACHING THE NORTHERN HIGH PLAINS. AT THE SURFACE...TROUGHING EXTENDS FROM SW SD INTO EASTERN CO. THIS HAS LEFT WARM MOIST FLOW OVER THE SOUTHERN AND CENTRAL PLAINS WHICH HAS ALLOWED LOW CLOUDS TO MOVE BACK IN ACROSS MUCH OF THE FORECAST AREA. TONIGHT-SUN NIGHT: WITH THE LOW LEVEL WARM MOIST FLOW REMAINING IN PLACE...THINKING THAT THE LOW CLOUDS WILL MAINTAIN AND WILL LIKELY LOWER A BIT THIS EVENING. IN ADDITION ALSO FEEL THAT AFTER DARK SOME LIGHT FOG AND DRIZZLE WILL ACCOMPANY THE LOW CIGS. MID LEVEL LIFT WILL COMMENCE OVER CENTRAL AND NORTHEAST KS THIS EVENING WHICH SHOULD RESULT IN SOME LIGHT SHOWERS WITH SOME OF THESE SHOWERS TRANSITIONING TO SOME LIGHT SNOW AFTER AFTER 3 AM AS MUCH COLDER AIR STARTS TO SPILL-IN FROM THE NORTH. NOT EXPECTING ANYTHING IN THE WAY OF ACCUMULATION OVERNIGHT. JUST LIKE THE LAST FEW MODEL RUNS...THE MAIN PIECE OF ENERGY IS EXPECTED TO BREAK OFF INTO TWO PIECES. ONE WILL MOVE TOWARDS THE GREAT LAKES WHILE THE OTHER DIVES OVER THE DESERT SW AND EVENTUALLY THE SOUTHERN PLAINS. STILL THINKING THAT THE PRECIP ON SUN WILL PRIMARILY BE IN THE FORM OR FLURRIES AND SPRINKLES. THE EXCEPTION WOULD BE THE EAST AND NORTHEAST FRINGES OF THE FORECAST AREA WHERE THE DEEPER LIFT AND MOISTURE WILL BE SITUATED. EVEN THE LOCATIONS THAT DO SEEM SOME SNOW SHOWERS CAN EXPECT TO ONLY PICKUP VERY LIGHT AMOUNTS. THE MAIN STORY WITH THIS SYSTEM WILL CONTINUE TO BE THE COLDEST TEMPS OF THE SEASON SO FAR WITH SINGLE DIGITS A GOOD BET FOR MUCH OF CENTRAL KS MON MORNING. MON-SAT: THE LONGWAVE TROUGH IS EXPECTED TO POSITION ITSELF OVER THE CENTRAL CONUS TO START THE WORK WEEK AS ADDITIONAL UPPER IMPULSES DIVE DOWN THE BACKSIDE OF THE TROUGH AND ACROSS THE SOUTHERN PLAINS FOR MON NIGHT INTO TUE. THIS PATTERN WILL RESULT IN A CONTINUATION OF BELOW NORMAL TEMPS WITH THE MOISTURE AND ASSOCIATED PRECIP CHANCES PUSHED WELL EAST OF THE FORECAST AREA. BY MID WEEK THE UPPER PATTERN WILL QUICKLY TRANSITION FROM NW FLOW ALOFT TO SW FLOW BY WED AFTERNOON AS OUR NEXT SHORTWAVE DIGS OVER THE WEST COAST. THIS WILL GET THE PLAINS BACK INTO A WARMING PATTERN THAT WILL CONTINUE FOR THU INTO FRI. THE SHORTWAVE WILL START TO DIRECTLY IMPACT THE AREA BY FRI INTO SAT. THE ECMWF IS MUCH MORE COMPACT THE MORE PROGRESSIVE WITH THIS WAVE COMPARED TO THE GFS. REGARDLESS OF WHICH ONE VERIFIES IT APPEARS THE BEST SNOW CHANCES WILL BE NORTH OF THE FORECAST AREA WITH SOME SHOWERS AND EVEN A FEW STORMS POSSIBLE FOR FRI...TRANSITIONING TO SOME LIGHT SNOW OR FLURRIES FOR FRI NIGHT. LAWSON && .PRELIMINARY POINT TEMPS/POPS... WICHITA-KICT 35 38 13 35 / 10 10 10 0 HUTCHINSON 34 35 12 36 / 10 10 10 0 NEWTON 34 37 12 35 / 10 20 10 0 ELDORADO 36 39 14 34 / 10 20 10 0 WINFIELD-KWLD 37 39 15 36 / 10 20 10 0 RUSSELL 28 30 6 39 / 20 10 10 0 GREAT BEND 31 30 7 38 / 10 10 10 0 SALINA 31 32 10 37 / 20 10 10 0 MCPHERSON 34 35 11 36 / 20 10 10 0 COFFEYVILLE 44 45 19 36 / 10 30 10 10 CHANUTE 42 43 18 34 / 10 30 10 10 IOLA 41 43 17 33 / 10 30 10 10 PARSONS-KPPF 43 44 18 35 / 10 30 10 10 && .ICT WATCHES/WARNINGS/ADVISORIES... NONE. && $$
AREA FORECAST DISCUSSION
NWS GOODLAND KS
309 PM MST FRI DEC 7 2012 .SHORT TERM...(THIS EVENING THROUGH SATURDAY) ISSUED AT 144 PM MST FRI DEC 7 2012 LATEST SATELLITE IMAGERY DEPICTS AN UPPER LEVEL TROUGH AXIS EXTENDING FROM SOUTHEASTERN COLORADO NORTHEAST INTO NORTHERN MINNESOTA. BEHIND THE TROUGH AXIS RUC ANALYSIS PLACES A SHORT WAVE TROUGH OVER THE NE/SD LINE. AT THE SURFACE A PRE-FRONTAL TROUGH WAS MOVING SOUTHEAST THROUGH THE PLAINS. SUBSIDENCE BEHIND THE SHORT WAVE TROUGH AND TROUGH AXIS HAS LEAD TO CLEARING SKIES BEHIND THE SURFACE FEATURE. LATE THIS EVENING A WEAK SHORT WAVE TROUGH WILL DEVELOP OVER EASTERN COLORADO AND PROGRESS ACROSS THE WESTERN HALF OF THE TRI-STATE AREA. SREF/NAM ISENTROPIC ANALYSIS INDICATES LIFT AHEAD OF THE SHORT WAVE TROUGH AROUND 700MB WHERE POINT SOUNDINGS ALSO SATURATE. THE DRAWBACK IS A DRY LAYER BELOW THIS WHICH WILL LIMIT HOW MUCH SNOW WILL REACH THE GROUND. THE MCCOOK AND NORTON AREA HAD A SIMILAR SETUP THIS MORNING...WITH THE MCCOOK AIRPORT REPORTING DRIZZLE. WITH THIS IN MIND WILL PLACE A MENTION OF FLURRIES AHEAD OF THE SHORT WAVE TROUGH. THE FLURRIES WILL GENERALLY MOVE FROM SOUTHWEST TO NORTHEAST DURING THE NIGHT OVER THE WESTERN HALF OF THE AREA. SATURDAY THE SHORT WAVE TROUGH WILL CONTINUE TO MOVE ACROSS THE AREA DURING THE MORNING. HAVE THE FLURRIES CHANGING TO DRIZZLE DURING THE LATE MORNING AS SURFACE TEMPERATURES WARM INTO THE LOWER 30S. THE ISENTROPIC LIFT AHEAD OF THE TROUGH WILL EXIT THE AREA BY EARLY AFTERNOON. SOUTH WINDS WILL BE BREEZY DURING THE AFTERNOON AS 25KT 850MB WINDS MIX TO THE GROUND AND THE SURFACE PRESSURE GRADIENT TIGHTENS. THE BREEZY WINDS WILL HELP WARM TEMPERATURES AHEAD OF THE NEXT COLD FRONT...WHICH WILL MOVE INTO THE AREA DURING THE MID TO LATE AFTERNOON. LIFTING AND MOISTURE WILL BE BEST ALONG AND SHORTLY BEHIND THE FRONT. HOWEVER MODELS SHOW A FAIRLY DEEP DRY LAYER AS THE FRONT MOVES THROUGH...WHICH MAY LIMIT THE AMOUNT OF RAIN THAT REACHES THE GROUND. MODELS SHOW RAPID PRESSURE RISE BEHIND THE COLD FRONT...WHICH WILL CAUSE WINDS TO STRENGTHEN BEHIND THE FRONT. .LONG TERM...(SATURDAY NIGHT THROUGH FRIDAY) ISSUED AT 247 PM MST FRI DEC 7 2012 THE COLD FRONT WILL CONTINUE TO PUSH ACROSS THE FORECAST AREA SATURDAY NIGHT. THE FAVORED AREA OF PRECIPITATION WILL INITIALLY BE ACROSS THE NORTHERN SECTIONS OF THE FORECAST AREA IN THE VICINITY OF THE FRONT WITH LIGHT RAIN CHANGING QUICKLY OVER TO LIGHT SNOW AROUND SUNSET. A SLIGHT CHANCE OF LIGHT SNOW WILL SPREAD ACROSS THE FORECAST AREA WITH THE FRONT...WITH THE BEST CHANCE OF PRECIPITATION REMAINING ALONG THE NORTHERN TIER OF COUNTIES WHERE THE SYNOPTIC SCALE LIFT REMAINS GREATER AS A SERIES OF SHORT WAVES SHEAR OUT ACROSS THE PLAINS AHEAD OF THE MAIN UPPER TROUGH. THE POSSIBILITY OF PRECIPITATION DECREASES THROUGH THE REMAINDER OF SATURDAY NIGHT AND SUNDAY MORNING...WITH LIGHT SNOW ENDING BY MID DAY ON SUNDAY. WITH THE STEEP PRESSURE GRADIENT REMAINING OVER THE CENTRAL HIGH PLAINS REGION...EXPECT NORTH WINDS OF 20-30 MPH WILL BE COMMON DURING THE DAY ON SUNDAY. THE PRIMARY DEEP UPPER TROUGH SWEEPS QUICKLY THROUGH THE REGION SUNDAY NIGHT WITH A COLD AREA OF HIGH PRESSURE MOVING IN BEHIND THE FRONT. OVERNIGHT LOW TEMPERATURES WILL DROP INTO THE SINGLE DIGITS AS SKIES ALSO BEGIN TO CLEAR OUT AND WINDS SLACKEN SUNDAY NIGHT. A SERIES OF OPEN WAVES WILL MOVE THROUGH THE UPPER FLOW NEXT WEEK. ALTHOUGH THE PATTERN REMAINS ACTIVE...NO ADDITIONAL PRECIPITATION IS EXPECTED THROUGH NEXT WEEK. COLDER TEMPERATURES WILL CONTINUE INTO THE BEGINNING OF NEXT WEEK WITH A GRADUAL WARMING BRINGING TEMPERATURES BACK TO NEAR AVERAGE FOR THIS TIME OF YEAR THROUGH THE MIDDLE AND END OF NEXT WEEK. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON) ISSUED AT 1042 AM MST FRI DEC 7 2012 VFR CONDITIONS ARE EXPECTED THROUGH THE TAF PERIOD AT BOTH GLD AND MCK. A LEE SURFACE TROUGH WILL SOON PUSH THROUGH BOTH TERMINALS...TURNING WINDS FROM THE SOUTHWEST TO NORTH-NORTHWEST. SKIES WILL BE CLEAR TODAY BEHIND THE TROUGH BEFORE MID LEVEL CLOUDS INCREASE LATE TONIGHT DUE TO A WEAK MID-LEVEL DISTURBANCE. WINDS WILL TURN BACK TO THE SOUTH-SOUTHWEST BY TOMORROW MORNING BEHIND THIS DISTURBANCE. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...NONE. CO...NONE. NE...NONE. && $$ SHORT TERM...JTL LONG TERM...LOCKHART AVIATION...JJM
AREA FORECAST DISCUSSION
NWS GOODLAND KS
156 PM MST FRI DEC 7 2012 .SHORT TERM...(THIS EVENING THROUGH SATURDAY) ISSUED AT 144 PM MST FRI DEC 7 2012 LATEST SATELLITE IMAGERY DEPICTS AN UPPER LEVEL TROUGH AXIS EXTENDING FROM SOUTHEASTERN COLORADO NORTHEAST INTO NORTHERN MINNESOTA. BEHIND THE TROUGH AXIS RUC ANALYSIS PLACES A SHORT WAVE TROUGH OVER THE NE/SD LINE. AT THE SURFACE A PRE-FRONTAL TROUGH WAS MOVING SOUTHEAST THROUGH THE PLAINS. SUBSIDENCE BEHIND THE SHORT WAVE TROUGH AND TROUGH AXIS HAS LEAD TO CLEARING SKIES BEHIND THE SURFACE FEATURE. LATE THIS EVENING A WEAK SHORT WAVE TROUGH WILL DEVELOP OVER EASTERN COLORADO AND PROGRESS ACROSS THE WESTERN HALF OF THE TRI-STATE AREA. SREF/NAM ISENTROPIC ANALYSIS INDICATES LIFT AHEAD OF THE SHORT WAVE TROUGH AROUND 700MB WHERE POINT SOUNDINGS ALSO SATURATE. THE DRAWBACK IS A DRY LAYER BELOW THIS WHICH WILL LIMIT HOW MUCH SNOW WILL REACH THE GROUND. THE MCCOOK AND NORTON AREA HAD A SIMILAR SETUP THIS MORNING...WITH THE MCCOOK AIRPORT REPORTING DRIZZLE. WITH THIS IN MIND WILL PLACE A MENTION OF FLURRIES AHEAD OF THE SHORT WAVE TROUGH. THE FLURRIES WILL GENERALLY MOVE FROM SOUTHWEST TO NORTHEAST DURING THE NIGHT OVER THE WESTERN HALF OF THE AREA. SATURDAY THE SHORT WAVE TROUGH WILL CONTINUE TO MOVE ACROSS THE AREA DURING THE MORNING. HAVE THE FLURRIES CHANGING TO DRIZZLE DURING THE LATE MORNING AS SURFACE TEMPERATURES WARM INTO THE LOWER 30S. THE ISENTROPIC LIFT AHEAD OF THE TROUGH WILL EXIT THE AREA BY EARLY AFTERNOON. SOUTH WINDS WILL BE BREEZY DURING THE AFTERNOON AS 25KT 850MB WINDS MIX TO THE GROUND AND THE SURFACE PRESSURE GRADIENT TIGHTENS. THE BREEZY WINDS WILL HELP WARM TEMPERATURES AHEAD OF THE NEXT COLD FRONT...WHICH WILL MOVE INTO THE AREA DURING THE MID TO LATE AFTERNOON. LIFTING AND MOISTURE WILL BE BEST ALONG AND SHORTLY BEHIND THE FRONT. HOWEVER MODELS SHOW A FAIRLY DEEP DRY LAYER AS THE FRONT MOVES THROUGH...WHICH MAY LIMIT THE AMOUNT OF RAIN THAT REACHES THE GROUND. MODELS SHOW RAPID PRESSURE RISE BEHIND THE COLD FRONT...WHICH WILL CAUSE WINDS TO STRENGTHEN BEHIND THE FRONT. .LONG TERM...(MONDAY THROUGH THURSDAY) ISSUED AT 231 AM MST FRI DEC 7 2012 TROUGH WILL REMAIN IN PLACE ACROSS THE HIGH/CENTRAL PLAINS THROUGH TUESDAY WITH SHORTWAVE RIDGE BUILDING BACK INTO THE INTER-MOUNTAIN WEST BY WEDNESDAY. RESULT WILL BE A GRADUAL WARM-UP WITH BELOW NORMAL HIGH TEMPS IN THE 30S MONDAY AND UPPER 30S/LOW 40S TUESDAY. THERE IS QUITE A BIT OF SPREAD BETWEEN ECMWF AND GFS REGARDING SHORTWAVE RIDGE WED. FOR NOW ABOVE NORMAL TEMPS IN THE UPPER 40S ARE FORECAST...HOWEVER SPREAD IN GUIDANCE COULD SUPPORT TEMPS 5F COOLER OR WARMER THAN THIS. HIGH TEMPS SHOULD BE NEAR SEASONAL LEVELS THU...THOUGH THERE IS INDICATION FROM PREVIOUS MODEL RUNS OF POSSIBLE FROPA THAT COULD RESULT IN SLIGHTLY COOLER TEMPS THAN CURRENTLY IN THERE. NOT ENOUGH CONFIDENCE TO GO LOWER THAN UPPER 30S/LOW 40S FOR HIGHS THU. SUBSIDENCE AND DRY AIR MASS SHOULD BE IN PLACE THROUGH THURSDAY...SO I LEFT FORECAST DRY. BY THE END OF NEXT WEEK ANOTHER TROUGH WILL BUILD OVER THE WESTERN US TOWARDS THE INTER-MOUNTAIN WEST THAT COULD BRING ANOTHER ARCTIC AIR MASS AND POSSIBLE SNOW CHANCES BY NEXT WEEKEND. THIS IS PRIMARILY OUTSIDE THE VALID FORECAST PERIOD...SO WILL NOT AFFECT THE ONGOING FORECAST. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON) ISSUED AT 1042 AM MST FRI DEC 7 2012 VFR CONDITIONS ARE EXPECTED THROUGH THE TAF PERIOD AT BOTH GLD AND MCK. A LEE SURFACE TROUGH WILL SOON PUSH THROUGH BOTH TERMINALS...TURNING WINDS FROM THE SOUTHWEST TO NORTH-NORTHWEST. SKIES WILL BE CLEAR TODAY BEHIND THE TROUGH BEFORE MID LEVEL CLOUDS INCREASE LATE TONIGHT DUE TO A WEAK MID-LEVEL DISTURBANCE. WINDS WILL TURN BACK TO THE SOUTH-SOUTHWEST BY TOMORROW MORNING BEHIND THIS DISTURBANCE. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...NONE. CO...NONE. NE...NONE. && $$ SHORT TERM...JTL LONG TERM...DR AVIATION...JJM
AREA FORECAST DISCUSSION
NWS GOODLAND KS
1042 AM MST FRI DEC 7 2012 .UPDATE... ISSUED AT 748 AM MST FRI DEC 7 2012 RADAR IMAGERY OVER THE LAST HOUR HAS SHOWN SOME WEAK ECHOES OVER THE MCCOOK AND NORTON AREAS. SURFACE TEMPERATURES HAVE BEEN AROUND 30 DEGREES AND THE RUC SOUNDING FROM MCCOOK INDICATED NO ICE BEING INTRODUCED INTO THE MID/LOW LEVEL CLOUDS. CALLED THE MCCOOK DISPATCH WHO REPORTED DRIZZLE...WITH NO ICE ACCUMULATING EVEN ON ELEVATED SURFACES. WITH THIS IN MIND...AND TEMPERATURES CONTINUING TO WARM...DECIDED TO CALL THIS DRIZZLE FOR THE FORECAST. ISENTROPIC ANALYSIS INDICATES THE LIFT FOR THIS AREA WILL LAST THROUGH THE MORNING THEN MOVE EAST OUT OF THE AREA DURING THE EARLY AFTERNOON AHEAD OF THE WEAK COLD FRONT. ALSO MENTION SLIGHTLY REDUCED VISIBILITIES IN THE DRIZZLE DUE TO MCCOOK REPORTING 4 MILES BRIEFLY THIS MORNING. && .SHORT TERM...(TODAY THROUGH SUNDAY NIGHT) ISSUED AT 231 AM MST FRI DEC 7 2012 AS OF 2 AM...SKIES ACROSS THE TRI-STATE AREA WERE PARTLY CLOUDY TO MOSTLY CLOUDY. TEMPERATURES WERE IN THE MID 20S TO MID 30S ACROSS THE REGION. WINDS WERE GENERALLY LIGHT BUT SOUTH WINDS HAVE STARTED TO PICK UP A LITTLE OVER EASTERN COLORADO AHEAD OF A DEVELOPING LEE TROUGH. THE LEE TROUGH WILL MOVE ACROSS THE REGION THIS AFTERNOON...ALLOWING SOUTH WINDS TO BECOME NORTHWEST WINDS AFTER THE TROUGH PASSAGE. SKY FORECAST FOR TODAY IS SOMEWHAT TRICKY AND LARGELY DEPENDS ON THE AMOUNT OF CIRRUS THAT DEVELOPS TO THE WEST. WENT WITH PARTLY CLOUDY SKIES FOR MOST OF THE DAY. HIGH TEMPERATURES WILL BE IN THE LOW TO MID 50S FOR TODAY. THIS WILL BE THE WARMEST DAY FOR AT LEAST THE NEXT WEEK AS A FEW COLD FRONTS WILL MOVE THROUGH AND KEEP THINGS QUITE COLD. A LARGE LONGWAVE TROUGH WILL BEGIN PUSHING INTO THE AREA ON SATURDAY. MODELS ARE BEGINNING TO AGREE ON A SOLUTION THAT IS NOT TOO FAVORABLE FOR PRECIPITATION IN THE REGION. MODELS ARE PROJECTING A SPLIT FLOW PATTERN WITH THE TRI-STATE AREA IN THE MIDDLE. ALL MODELS ALSO SHOW THAT TWO SEPARATE LOW PRESSURE SYSTEMS WILL DEVELOP AHEAD OF THIS UPPER LEVEL DISTURBANCE. THE FIRST WILL DEVELOP OVER THE NORTHERN PLAINS. THIS LOW PRESSURE WILL MOVE TOWARDS MINNESOTA AND KEEP MOST OF THE BEST FORCING AND PRECIPITATION OVER NEBRASKA AND SOUTH DAKOTA. THE SECOND LOW PRESSURE WILL DEVELOP TO THE SOUTH...OVER THE TEXAS PANHANDLE. THIS SECOND SOLUTION WOULD FAVOR A BETTER CHANCE FOR PRECIPITATION ACROSS KANSAS. MODELS DISAGREE ON HOW STRONG THE LOW PRESSURES WILL BE. THE EUROPEAN IS THE ONLY MODEL THAT SHOWS THE SOUTHERN LOW BECOMING THE DOMINANT LOW...WHICH WOULD BE MORE FAVORABLE FOR PRECIPITATION HERE IN THE TRI-STATE AREA. UNFORTUNATELY...THE PRECIPITATION FOR THE EUROPEAN MODEL LOOKS A LITTLE OVERDONE CONSIDERING THE AMOUNT OF DRY AIR THAT WILL MOVE IN WITH THIS FRONT. AS A RESULT...HAVE LEANED TOWARDS THE DRIER SOLUTIONS OF THE NAM...CANADIAN AND GFS MODELS. THE MODELS DO HAVE SOME VARIABLES THAT WOULD FAVOR HIGHER SNOWFALL AMOUNTS...HOWEVER THE AMOUNT OF DRY AIR LOOKS LIKE TOO MUCH TO OVERCOME AT THE PRESENT MOMENT. MODEL CONSISTENCY IS INCREASING WITH THE EUROPEAN REMAINING AS THE ONLY OUTLIER. THE COLD FRONT WILL PASS THROUGH LATE SATURDAY EVENING AND INTO SATURDAY NIGHT. SOME SNOW SHOWERS ARE POSSIBLE ALONG THE FRONT...HOWEVER DUE TO THE DRY AIR ACCUMULATIONS WILL LIKELY BE ONE INCH OR LESS. TEMPERATURES WILL BE QUITE COLD BEHIND THE FRONT WITH STRONG NORTH WINDS. HIGH TEMPERATURES ON SUNDAY WILL LIKELY NOT MAKE IT INTO THE 30S. LOW TEMPERATURES ON SUNDAY NIGHT WILL FALL INTO THE SINGLE DIGITS ACROSS MOST OF THE REGION...WITH WIND CHILL READINGS AS LOW AS ZERO OR POSSIBLY BELOW ZERO. LOW TEMPERATURES COULD FALL LOWER THAN FORECAST IF SKIES CLEAR QUICKER THAN EXPECTED AS A DRY SLOT MOVES INTO THE BACK OF THE DEPARTING WEATHER SYSTEM. .LONG TERM...(MONDAY THROUGH THURSDAY) ISSUED AT 231 AM MST FRI DEC 7 2012 TROUGH WILL REMAIN IN PLACE ACROSS THE HIGH/CENTRAL PLAINS THROUGH TUESDAY WITH SHORTWAVE RIDGE BUILDING BACK INTO THE INTER-MOUNTAIN WEST BY WEDNESDAY. RESULT WILL BE A GRADUAL WARM-UP WITH BELOW NORMAL HIGH TEMPS IN THE 30S MONDAY AND UPPER 30S/LOW 40S TUESDAY. THERE IS QUITE A BIT OF SPREAD BETWEEN ECMWF AND GFS REGARDING SHORTWAVE RIDGE WED. FOR NOW ABOVE NORMAL TEMPS IN THE UPPER 40S ARE FORECAST...HOWEVER SPREAD IN GUIDANCE COULD SUPPORT TEMPS 5F COOLER OR WARMER THAN THIS. HIGH TEMPS SHOULD BE NEAR SEASONAL LEVELS THU...THOUGH THERE IS INDICATION FROM PREVIOUS MODEL RUNS OF POSSIBLE FROPA THAT COULD RESULT IN SLIGHTLY COOLER TEMPS THAN CURRENTLY IN THERE. NOT ENOUGH CONFIDENCE TO GO LOWER THAN UPPER 30S/LOW 40S FOR HIGHS THU. SUBSIDENCE AND DRY AIR MASS SHOULD BE IN PLACE THROUGH THURSDAY...SO I LEFT FORECAST DRY. BY THE END OF NEXT WEEK ANOTHER TROUGH WILL BUILD OVER THE WESTERN US TOWARDS THE INTER-MOUNTAIN WEST THAT COULD BRING ANOTHER ARCTIC AIR MASS AND POSSIBLE SNOW CHANCES BY NEXT WEEKEND. THIS IS PRIMARILY OUTSIDE THE VALID FORECAST PERIOD...SO WILL NOT AFFECT THE ONGOING FORECAST. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON) ISSUED AT 1042 AM MST FRI DEC 7 2012 VFR CONDITIONS ARE EXPECTED THROUGH THE TAF PERIOD AT BOTH GLD AND MCK. A LEE SURFACE TROUGH WILL SOON PUSH THROUGH BOTH TERMINALS...TURNING WINDS FROM THE SOUTHWEST TO NORTH-NORTHWEST. SKIES WILL BE CLEAR TODAY BEHIND THE TROUGH BEFORE MID LEVEL CLOUDS INCREASE LATE TONIGHT DUE TO A WEAK MID-LEVEL DISTURBANCE. WINDS WILL TURN BACK TO THE SOUTH-SOUTHWEST BY TOMORROW MORNING BEHIND THIS DISTURBANCE. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...NONE. CO...NONE. NE...NONE. && $$ UPDATE...JTL SHORT TERM...RRH LONG TERM...DR AVIATION...JJM
AREA FORECAST DISCUSSION
NWS GOODLAND KS
758 AM MST FRI DEC 7 2012 .UPDATE... ISSUED AT 748 AM MST FRI DEC 7 2012 RADAR IMAGERY OVER THE LAST HOUR HAS SHOWN SOME WEAK ECHOES OVER THE MCCOOK AND NORTON AREAS. SURFACE TEMPERATURES HAVE BEEN AROUND 30 DEGREES AND THE RUC SOUNDING FROM MCCOOK INDICATED NO ICE BEING INTRODUCED INTO THE MID/LOW LEVEL CLOUDS. CALLED THE MCCOOK DISPATCH WHO REPORTED DRIZZLE...WITH NO ICE ACCUMULATING EVEN ON ELEVATED SURFACES. WITH THIS IN MIND...AND TEMPERATURES CONTINUING TO WARM...DECIDED TO CALL THIS DRIZZLE FOR THE FORECAST. ISENTROPIC ANALYSIS INDICATES THE LIFT FOR THIS AREA WILL LAST THROUGH THE MORNING THEN MOVE EAST OUT OF THE AREA DURING THE EARLY AFTERNOON AHEAD OF THE WEAK COLD FRONT. ALSO MENTION SLIGHTLY REDUCED VISIBILITIES IN THE DRIZZLE DUE TO MCCOOK REPORTING 4 MILES BRIEFLY THIS MORNING. && .SHORT TERM...(TODAY THROUGH SUNDAY NIGHT) ISSUED AT 231 AM MST FRI DEC 7 2012 AS OF 2 AM...SKIES ACROSS THE TRI-STATE AREA WERE PARTLY CLOUDY TO MOSTLY CLOUDY. TEMPERATURES WERE IN THE MID 20S TO MID 30S ACROSS THE REGION. WINDS WERE GENERALLY LIGHT BUT SOUTH WINDS HAVE STARTED TO PICK UP A LITTLE OVER EASTERN COLORADO AHEAD OF A DEVELOPING LEE TROUGH. THE LEE TROUGH WILL MOVE ACROSS THE REGION THIS AFTERNOON...ALLOWING SOUTH WINDS TO BECOME NORTHWEST WINDS AFTER THE TROUGH PASSAGE. SKY FORECAST FOR TODAY IS SOMEWHAT TRICKY AND LARGELY DEPENDS ON THE AMOUNT OF CIRRUS THAT DEVELOPS TO THE WEST. WENT WITH PARTLY CLOUDY SKIES FOR MOST OF THE DAY. HIGH TEMPERATURES WILL BE IN THE LOW TO MID 50S FOR TODAY. THIS WILL BE THE WARMEST DAY FOR AT LEAST THE NEXT WEEK AS A FEW COLD FRONTS WILL MOVE THROUGH AND KEEP THINGS QUITE COLD. A LARGE LONGWAVE TROUGH WILL BEGIN PUSHING INTO THE AREA ON SATURDAY. MODELS ARE BEGINNING TO AGREE ON A SOLUTION THAT IS NOT TOO FAVORABLE FOR PRECIPITATION IN THE REGION. MODELS ARE PROJECTING A SPLIT FLOW PATTERN WITH THE TRI-STATE AREA IN THE MIDDLE. ALL MODELS ALSO SHOW THAT TWO SEPARATE LOW PRESSURE SYSTEMS WILL DEVELOP AHEAD OF THIS UPPER LEVEL DISTURBANCE. THE FIRST WILL DEVELOP OVER THE NORTHERN PLAINS. THIS LOW PRESSURE WILL MOVE TOWARDS MINNESOTA AND KEEP MOST OF THE BEST FORCING AND PRECIPITATION OVER NEBRASKA AND SOUTH DAKOTA. THE SECOND LOW PRESSURE WILL DEVELOP TO THE SOUTH...OVER THE TEXAS PANHANDLE. THIS SECOND SOLUTION WOULD FAVOR A BETTER CHANCE FOR PRECIPITATION ACROSS KANSAS. MODELS DISAGREE ON HOW STRONG THE LOW PRESSURES WILL BE. THE EUROPEAN IS THE ONLY MODEL THAT SHOWS THE SOUTHERN LOW BECOMING THE DOMINANT LOW...WHICH WOULD BE MORE FAVORABLE FOR PRECIPITATION HERE IN THE TRI-STATE AREA. UNFORTUNATELY...THE PRECIPITATION FOR THE EUROPEAN MODEL LOOKS A LITTLE OVERDONE CONSIDERING THE AMOUNT OF DRY AIR THAT WILL MOVE IN WITH THIS FRONT. AS A RESULT...HAVE LEANED TOWARDS THE DRIER SOLUTIONS OF THE NAM...CANADIAN AND GFS MODELS. THE MODELS DO HAVE SOME VARIABLES THAT WOULD FAVOR HIGHER SNOWFALL AMOUNTS...HOWEVER THE AMOUNT OF DRY AIR LOOKS LIKE TOO MUCH TO OVERCOME AT THE PRESENT MOMENT. MODEL CONSISTENCY IS INCREASING WITH THE EUROPEAN REMAINING AS THE ONLY OUTLIER. THE COLD FRONT WILL PASS THROUGH LATE SATURDAY EVENING AND INTO SATURDAY NIGHT. SOME SNOW SHOWERS ARE POSSIBLE ALONG THE FRONT...HOWEVER DUE TO THE DRY AIR ACCUMULATIONS WILL LIKELY BE ONE INCH OR LESS. TEMPERATURES WILL BE QUITE COLD BEHIND THE FRONT WITH STRONG NORTH WINDS. HIGH TEMPERATURES ON SUNDAY WILL LIKELY NOT MAKE IT INTO THE 30S. LOW TEMPERATURES ON SUNDAY NIGHT WILL FALL INTO THE SINGLE DIGITS ACROSS MOST OF THE REGION...WITH WIND CHILL READINGS AS LOW AS ZERO OR POSSIBLY BELOW ZERO. LOW TEMPERATURES COULD FALL LOWER THAN FORECAST IF SKIES CLEAR QUICKER THAN EXPECTED AS A DRY SLOT MOVES INTO THE BACK OF THE DEPARTING WEATHER SYSTEM. .LONG TERM...(MONDAY THROUGH THURSDAY) ISSUED AT 231 AM MST FRI DEC 7 2012 TROUGH WILL REMAIN IN PLACE ACROSS THE HIGH/CENTRAL PLAINS THROUGH TUESDAY WITH SHORTWAVE RIDGE BUILDING BACK INTO THE INTER-MOUNTAIN WEST BY WEDNESDAY. RESULT WILL BE A GRADUAL WARM-UP WITH BELOW NORMAL HIGH TEMPS IN THE 30S MONDAY AND UPPER 30S/LOW 40S TUESDAY. THERE IS QUITE A BIT OF SPREAD BETWEEN ECMWF AND GFS REGARDING SHORTWAVE RIDGE WED. FOR NOW ABOVE NORMAL TEMPS IN THE UPPER 40S ARE FORECAST...HOWEVER SPREAD IN GUIDANCE COULD SUPPORT TEMPS 5F COOLER OR WARMER THAN THIS. HIGH TEMPS SHOULD BE NEAR SEASONAL LEVELS THU...THOUGH THERE IS INDICATION FROM PREVIOUS MODEL RUNS OF POSSIBLE FROPA THAT COULD RESULT IN SLIGHTLY COOLER TEMPS THAN CURRENTLY IN THERE. NOT ENOUGH CONFIDENCE TO GO LOWER THAN UPPER 30S/LOW 40S FOR HIGHS THU. SUBSIDENCE AND DRY AIR MASS SHOULD BE IN PLACE THROUGH THURSDAY...SO I LEFT FORECAST DRY. BY THE END OF NEXT WEEK ANOTHER TROUGH WILL BUILD OVER THE WESTERN US TOWARDS THE INTER-MOUNTAIN WEST THAT COULD BRING ANOTHER ARCTIC AIR MASS AND POSSIBLE SNOW CHANCES BY NEXT WEEKEND. THIS IS PRIMARILY OUTSIDE THE VALID FORECAST PERIOD...SO WILL NOT AFFECT THE ONGOING FORECAST. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SATURDAY MORNING) ISSUED AT 423 AM MST FRI DEC 7 2012 VFR CONDITIONS ARE EXPECTED TO CONTINUE FOR THE NEXT 24 HOURS. MID-LEVEL CLOUDS HAVE DEVELOPED OVER THE TAF SITES THIS MORNING BUT SHOULD DISSIPATE LATER THIS MORNING. HIGH-LEVEL CIRRUS WILL CONTINUE TO STREAM OVER WITH MID-LEVEL CLOUDS EXPECTED TO DEVELOP AGAIN TONIGHT. SOUTH WINDS WILL BECOME NORTH WINDS ON THE BACK SIDE OF A LEE TROUGH THAT WILL MOVE THROUGH THIS AFTERNOON. WINDS WILL AGAIN BECOME SOUTH DURING THE OVERNIGHT HOURS TONIGHT. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...NONE. CO...NONE. NE...NONE. && $$ UPDATE...JTL SHORT TERM...RRH LONG TERM...DR AVIATION...RRH
AREA FORECAST DISCUSSION
NWS LAKE CHARLES LA
1143 AM CST FRI DEC 7 2012 .AVIATION...A CU FIELD IS CURRENTLY DEVELOPING ACROSS SE TX AND IS SPREADING INTO LA. THIS TREND WILL CONTINUE THROUGH THE NEXT FEW HRS AS HEATING OCCURS. MVFR CEILINGS WILL BE POSSIBLE INTO THE LATE AFTERNOON TO EARLY EVENING. THE CU WILL BREAK UP AROUND SUNSET, HOWEVER FOG WILL BEGIN TO DEVELOP BEFORE MIDNIGHT. HIGH CLOUDS MAY INHIBIT SOME FOG, HOWEVER MOST TERMINALS WILL STILL BE AFFECTED. IFR AND POTENTIALLY LIFR CONDITIONS WILL BE POSSIBLE INTO SAT MORNING. WINDS WILL BE SE TO S AT 10KTS OR LESS. && .PREV DISCUSSION... /ISSUED 936 AM CST FRI DEC 7 2012/ UPDATE... FOG IS BEGINNING TO LIFT THIS MORNING AND WILL END THE DENSE FOG ADVISORY. OTHERWISE SKIES WILL BE CLEARING ALLOWING TEMPERATURES TO WARM INTO THE MID 70S TODAY. WE ARE IN THIS SAME PATTERN FOR TOMORROW WITH CHANGES IN THE WEATHER TO BEGIN ON SUNDAY AS ANOTHER COLD FRONT DROPS DOWN FROM THE PLAINS STATES. PREV DISCUSSION... /ISSUED 608 AM CST FRI DEC 7 2012/ AVIATION...BLO MINS CONDITIONS EXCEPT BPT WHERE STRATCU CIGS STAYED IN MOST OF THE NIGHT AND WINDS WERE A BIT STRONGER AND SWLY AT GRADIENT LEVELS. OTHERWISE IMPROVEMENT ABV MINS SHORTLY AT AEX, AND IN A COUPLE OF HOURS AT LCH AS SWLY BOUNDARY LEVEL FLOW BEGINS TO LIFT THE FOG TOWARDS MVFR. BY MID MORNING ACADIANA AIRPORTS ARA AND LFT SHOULD FOLLOW SUIT AS TEMPS APPROACH BURNOFF OF 65F/18C. STILL LOOKING VFR FOR AEX AS WELL AS LFT AND ARA THIS AFTERNOON. MVFR CIGS SHOULD HANG IN THE REST OF THE DAY AT BPT AND LCH LOOKING AT LATEST RUC TRENDS. VLIFR CONDITIONS SHOULD REPEAT STARTING LATE EVENING AS THE WEAK DECEMBER SUN AND AN INVERSION HAS TRAPPED LOW LEVEL MOISTURE IN PLACE. SWEENEY PREV DISCUSSION... /ISSUED 412 AM CST FRI DEC 7 2012/ SYNOPSIS... AN ATLANTIC DOME OF HIGH PRESSURE...LOCATED OFFSHORE THE CAROLINA`S...RIDGES WESTWARD THROUGH SOUTHEAST LOUISIANA. DISCUSSION... DRY MEXICAN AIR IS RIDING IN ON A LOW LEVEL SOUTHWESTERLY AIRSTREAM. THE OVERRIDING DRY AIR IS TRAPPING MOISTURE NEAR THE SURFACE. PATCHY DENSE FOG IS BEING REPORTED THROUGH MOST OF SOUTHWEST LOUISIANA. A DENSE FOG ADVISORY WILL REMAIN IN EFFECT. OTHERWISE...A WARM CONVEYOR BELT AIRSTREAM IS BECOMING BETTER ESTABLISHED WITHIN THE SURFACE LAYER. CAMPECHE AIR IS RIDING IN ON INCREASING SOUTHERLY WINDS. THE AFTERNOON READINGS WILL BE RUNNING FROM 10 TO 15 DEGREES ABOVE NORMAL. THE AFTERNOON HUMIDITIES WILL BE RUNNING WELL ABOVE NORMAL. FOR TONIGHT...PATCHY FOG IS EXPECTED TO RETURN. OTHERWISE...THE OVERNIGHT MINIMUMS WILL BE RUNNING FROM 15 TO 20 DEGREES ABOVE NORMAL. OUTLOOK... A STRONG CANADIAN FRONT WILL TRAVEL THROUGH THE FORECAST AREA DURING THE OVERNIGHT HOURS ON SUNDAY. NUMEROUS SHOWERS AND THUNDERSTORMS WILL ACCOMPANY THIS SYSTEM. 21 && .PRELIMINARY POINT TEMPS/POPS... KLCH 75 60 78 61 77 / 10 10 10 10 20 KBPT 75 61 78 63 77 / 10 10 20 10 20 KAEX 74 57 77 59 77 / 10 10 10 10 20 KLFT 75 59 78 59 77 / 10 10 10 10 20 && .LCH WATCHES/WARNINGS/ADVISORIES... LA...NONE. TX...NONE. GM...NONE. && $$
AREA FORECAST DISCUSSION
NWS LAKE CHARLES LA
936 AM CST FRI DEC 7 2012 .UPDATE... FOG IS BEGINNING TO LIFT THIS MORNING AND WILL END THE DENSE FOG ADVISORY. OTHERWISE SKIES WILL BE CLEARING ALLOWING TEMPERATURES TO WARM INTO THE MID 70S TODAY. WE ARE IN THIS SAME PATTERN FOR TOMORROW WITH CHANGES IN THE WEATHER TO BEGIN ON SUNDAY AS ANOTHER COLD FRONT DROPS DOWN FROM THE PLAINS STATES. && .PREV DISCUSSION... /ISSUED 608 AM CST FRI DEC 7 2012/ AVIATION...BLO MINS CONDITIONS EXCEPT BPT WHERE STRATCU CIGS STAYED IN MOST OF THE NIGHT AND WINDS WERE A BIT STRONGER AND SWLY AT GRADIENT LEVELS. OTHERWISE IMPROVEMENT ABV MINS SHORTLY AT AEX, AND IN A COUPLE OF HOURS AT LCH AS SWLY BOUNDARY LEVEL FLOW BEGINS TO LIFT THE FOG TOWARDS MVFR. BY MID MORNING ACADIANA AIRPORTS ARA AND LFT SHOULD FOLLOW SUIT AS TEMPS APPROACH BURNOFF OF 65F/18C. STILL LOOKING VFR FOR AEX AS WELL AS LFT AND ARA THIS AFTERNOON. MVFR CIGS SHOULD HANG IN THE REST OF THE DAY AT BPT AND LCH LOOKING AT LATEST RUC TRENDS. VLIFR CONDITIONS SHOULD REPEAT STARTING LATE EVENING AS THE WEAK DECEMBER SUN AND AN INVERSION HAS TRAPPED LOW LEVEL MOISTURE IN PLACE. SWEENEY PREV DISCUSSION... /ISSUED 412 AM CST FRI DEC 7 2012/ SYNOPSIS... AN ATLANTIC DOME OF HIGH PRESSURE...LOCATED OFFSHORE THE CAROLINA`S...RIDGES WESTWARD THROUGH SOUTHEAST LOUISIANA. DISCUSSION... DRY MEXICAN AIR IS RIDING IN ON A LOW LEVEL SOUTHWESTERLY AIRSTREAM. THE OVERRIDING DRY AIR IS TRAPPING MOISTURE NEAR THE SURFACE. PATCHY DENSE FOG IS BEING REPORTED THROUGH MOST OF SOUTHWEST LOUISIANA. A DENSE FOG ADVISORY WILL REMAIN IN EFFECT. OTHERWISE...A WARM CONVEYOR BELT AIRSTREAM IS BECOMING BETTER ESTABLISHED WITHIN THE SURFACE LAYER. CAMPECHE AIR IS RIDING IN ON INCREASING SOUTHERLY WINDS. THE AFTERNOON READINGS WILL BE RUNNING FROM 10 TO 15 DEGREES ABOVE NORMAL. THE AFTERNOON HUMIDITIES WILL BE RUNNING WELL ABOVE NORMAL. FOR TONIGHT...PATCHY FOG IS EXPECTED TO RETURN. OTHERWISE...THE OVERNIGHT MINIMUMS WILL BE RUNNING FROM 15 TO 20 DEGREES ABOVE NORMAL. OUTLOOK... A STRONG CANADIAN FRONT WILL TRAVEL THROUGH THE FORECAST AREA DURING THE OVERNIGHT HOURS ON SUNDAY. NUMEROUS SHOWERS AND THUNDERSTORMS WILL ACCOMPANY THIS SYSTEM. 21 && .PRELIMINARY POINT TEMPS/POPS... KLCH 75 60 78 61 77 / 10 10 10 10 20 KBPT 75 61 78 63 77 / 10 10 20 10 20 KAEX 74 57 77 59 77 / 10 10 10 10 20 KLFT 75 59 78 59 77 / 10 10 10 10 20 && .LCH WATCHES/WARNINGS/ADVISORIES... LA...NONE. TX...NONE. GM...NONE. && $$
AREA FORECAST DISCUSSION
NWS LAKE CHARLES LA
608 AM CST FRI DEC 7 2012 .AVIATION...BLO MINS CONDITIONS EXCEPT BPT WHERE STRATCU CIGS STAYED IN MOST OF THE NIGHT AND WINDS WERE A BIT STRONGER AND SWLY AT GRADIENT LEVELS. OTHERWISE IMPROVEMENT ABV MINS SHORTLY AT AEX, AND IN A COUPLE OF HOURS AT LCH AS SWLY BOUNDARY LEVEL FLOW BEGINS TO LIFT THE FOG TOWARDS MVFR. BY MID MORNING ACADIANA AIRPORTS ARA AND LFT SHOULD FOLLOW SUIT AS TEMPS APPROACH BURNOFF OF 65F/18C. STILL LOOKING VFR FOR AEX AS WELL AS LFT AND ARA THIS AFTERNOON. MVFR CIGS SHOULD HANG IN THE REST OF THE DAY AT BPT AND LCH LOOKING AT LATEST RUC TRENDS. VLIFR CONDTIONS SHOULD REPEAT STARTING LATE EVENING AS THE WEAK DECEMBER SUN AND AN INVERSION HAS TRAPPED LOW LEVEL MOISTURE IN PLACE. SWEENEY && .PREV DISCUSSION... /ISSUED 412 AM CST FRI DEC 7 2012/ SYNOPSIS... AN ATLANTIC DOME OF HIGH PRESSURE...LOCATED OFFSHORE THE CAROLINAS...RIDGES WESTWARD THROUGH SOUTHEAST LOUISIANA. DISCUSSION... DRY MEXICAN AIR IS RIDING IN ON A LOW LEVEL SOUTHWESTERLY AIRSTREAM. THE OVERRIDING DRY AIR IS TRAPPING MOISTURE NEAR THE SURFACE. PATCHY DENSE FOG IS BEING REPORTED THROUGH MOST OF SOUTHWEST LOUISIANA. A DENSE FOG ADVISORY WILL REMAIN IN EFFECT. OTHERWISE...A WARM CONVEYOR BELT AIRSTREAM IS BECOMING BETTER ESTABLISHED WITHIN THE SURFACE LAYER. CAMPECHE AIR IS RIDING IN ON INCREASING SOUTHERLY WINDS. THE AFTERNOON READINGS WILL BE RUNNING FROM 10 TO 15 DEGREES ABOVE NORMAL. THE AFTERNOON HUMIDITIES WILL BE RUNNING WELL ABOVE NORMAL. FOR TONIGHT...PATCHY FOG IS EXPECTED TO RETURN. OTHERWISE...THE OVERNIGHT MINIMUMS WILL BE RUNNING FROM 15 TO 20 DEGREES ABOVE NORMAL. OUTLOOK... A STRONG CANADIAN FRONT WILL TRAVEL THROUGH THE FORECAST AREA DURING THE OVERNIGHT HOURS ON SUNDAY. NUMEROUS SHOWERS AND THUNDERSTORMS WILL ACCOMPANY THIS SYSTEM. 21 && .PRELIMINARY POINT TEMPS/POPS... KLCH 75 60 78 61 77 / 10 10 10 10 20 KBPT 75 61 78 63 77 / 10 10 20 10 20 KAEX 74 57 77 59 77 / 10 10 10 10 20 KLFT 75 59 78 59 77 / 10 10 10 10 20 && .LCH WATCHES/WARNINGS/ADVISORIES... LA...DENSE FOG ADVISORY UNTIL 9 AM CST THIS MORNING FOR THE FOLLOWING ZONES: ACADIA...ALLEN...AVOYELLES...BEAUREGARD... CALCASIEU...EAST CAMERON...EVANGELINE...IBERIA...JEFFERSON DAVIS...LAFAYETTE...LOWER ST. MARTIN...RAPIDES...ST. LANDRY...ST. MARY...UPPER ST. MARTIN...VERMILION...VERNON... WEST CAMERON. TX...NONE. GM...NONE. && $$
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
902 AM EST FRI DEC 7 2012 .SYNOPSIS... A STATIONARY FRONT WILL BE THE FOCUS FOR PERIODS OF RAIN ACROSS THE UPPER OHIO VALLEY INTO EARLY NEXT WEEK...AS A SERIES OF LOW PRESSURE SYSTEMS MOVE EASTWARD ALONG THE STALLED FRONT. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... MORNING UPDATE TO REMOVE ANY MENTION OF FREEZING RAIN OR DRIZZLE ACROSS THE FAR NORTH. BUMPED UP MAX TEMPERATURES A DEGREE OR SO ACROSS THE FAR SOUTH MAINLY KMGW TO ACCOUNT FOR CURRENT READINGS. PER RECENT RADAR DATA AND RAP MODEL OUTPUT...EXPECT FREQUENT PERIODS OF RAIN ACROSS THE UPPER OHIO VALLEY...AS THE INITIAL LOW PRESSURE CENTER MOVES NORTHEASTWARD ALONG THE STATIONARY FRONT THAT STRADDLES THE I-70 CORRIDOR. HIGHER ELEVATIONS CAN BE SHROUDED IN LOW CLOUDS...SO HAVE ADDED PATCHY FOG THIS MORNING FOR AREAS HIGHER THAN 2500 FT MSL. && .SHORT TERM /6 PM THIS EVENING THROUGH SUNDAY/... MILD AND WET WEA WL DOMINATE THE SHORT TERM PD AS A SERIES OF DISTURBANCES TRIGGER WARM...MOIST ADVCTN AND PCPN AS THEY MOVE ALONG A NEAR-STATIONARY FRONT PROJECTED OVR THE UPR OH VALLEY REGION. BREAKS IN THE PCPN CAN BE EXPECTED WITH PASSAGE OF THE INDIVIDUAL SHORTWAVES. WARM TEMPS WERE FORECAST USING A MIX OF SREF/MAV NUMBERS. && .LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/... CLOUDS AND WET WEATHER CONTINUE INTO EARLY NEXT WEEK. SHORTWAVE THAT IS PROJECTED ACRS THE GREAT LAKES ON MONDAY INTO TUESDAY IS FORECAST TO PUSH THE FRONT SUFFICIENTLY EWD TO END THE WET SPELL. COLD ADVCTN IN THE WAKE OF THE FRONT WITH UPSLOPE/LAKE ENHANCEMENT MAY SPPRT SOME SNOW SHOWERS FOR TUE AND TUE NGT...BUT DO NOT FORESEE MUCH ACCUM AT THIS JUNCTURE AS THE MAGNITUDE AND DEPTH OF THE COLD POOL RMNS QNABLE. SEASONAL TEMPERATURES AND DRY WX ARE EXPECTED TO QUICKLY RTN THOUGH AS SW FLOW RESUMES WED AND CONTS THROUGH THE BALANCE OF THE PERIOD. && .AVIATION /14Z FRIDAY THROUGH TUESDAY/... RECENT RADAR AND SURFACE DATA...COUPLED WITH RECENT RAP AND WRF- NMM MODEL OUTPUT...SHOWS SURGES OF RAIN...ASSOCIATED WITH LOW PRESSURE CENTERS MOVING NORTHEASTWARD ALONG THE I-70 STATIONARY FRONT...WILL CONTINUE TO MOVE NORTHEASTWARD ACROSS THE UPPER OHIO VALLEY TODAY INTO FRIDAY. AS RAIN-MOISTENED SURFACE LAYER SATURATES..CONDITIONS WILL LOWER TO MAINLY IFR BY 14Z...AND PERHAPS LIFR TONIGHT. SURFACE WINDS WILL BE MAINLY FROM THE SOUTH AT NO MORE THAN 10 KTS. .OUTLOOK.../SATURDAY NIGHT THROUGH TUESDAY/... FREQUENT IFR RESTRICTIONS DUE TO RAIN FOG AND STRATUS WILL CONTINUE INTO TUESDAY DUE TO A SERIES OF LOW PRESSURE SYSTEMS MOVING EASTWARD ALONG THE STALLED FRONT. && .PBZ WATCHES/WARNINGS/ADVISORIES... MD...NONE. OH...NONE. PA...NONE. WV...NONE. && $$
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
610 AM EST FRI DEC 7 2012 .SYNOPSIS... A STATIONARY FRONT WILL BE THE FOCUS FOR PERIODS OF RAIN ACROSS THE UPPER OHIO VALLEY INTO EARLY NEXT WEEK...AS A SERIES OF LOW PRESSURE SYSTEMS MOVE EASTWARD ALONG THE STALLED FRONT. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... PER RECENT RADAR DATA AND RAP MODEL OUTPUT...EXPECT FREQUENT PERIODS OF RAIN ACROSS THE UPPER OHIO VALLEY...AS THE INITIAL LOW PRESSURE CENTER MOVES NORTHEASTWARD ALONG THE STATIONARY FRONT THAT STRADDLES THE I-70 CORRIDOR. SURFACE DATA SUGGESTS AIR TEMPERATURES NEAR FREEZING CLOSE TO THE APPALACHIAN MOUNTAINS. HOWEVER ROAD SENSORS SUGGEST PAVEMENTS CAN BE WARMER. SO EXPECT ANY PATCHES OF FREEZING RAIN WILL HAVE ENDED BY DAYBREAK AT 7 AM...WITH TEMPERATURES CLIMBING TO VALUES UP TO 10 DEGREES WARMER THAN NORMAL THIS AFTERNOON PER RECENT GFS AND NAM MOS. HIGHER ELEVATIONS CAN BE SHROUDED IN LOW CLOUDS...SO HAVE ADDED PATCHY FOG THIS MORNING FOR AREAS HIGHER THAN 2500 FT MSL. && .SHORT TERM /6 PM THIS EVENING THROUGH SUNDAY/... MILD AND WET WEA WL DOMINATE THE SHORT TERM PD AS A SERIES OF DISTURBANCES TRIGGER WARM...MOIST ADVCTN AND PCPN AS THEY MOVE ALONG A NEAR-STATIONARY FRONT PROJECTED OVR THE UPR OH VALLEY REGION. BREAKS IN THE PCPN CAN BE EXPECTED WITH PASSAGE OF THE INDIVIDUAL SHORTWAVES. WARM TEMPS WERE FORECAST USING A MIX OF SREF/MAV NUMBERS. && .LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/... CLOUDS AND WET WEATHER CONTINUE INTO EARLY NEXT WEEK. SHORTWAVE THAT IS PROJECTED ACRS THE GREAT LAKES ON MONDAY INTO TUESDAY IS FORECAST TO PUSH THE FRONT SUFFICIENTLY EWD TO END THE WET SPELL. COLD ADVCTN IN THE WAKE OF THE FRONT WITH UPSLOPE/LAKE ENHANCEMENT MAY SPPRT SOME SNOW SHOWERS FOR TUE AND TUE NGT...BUT DO NOT FORESEE MUCH ACCUM AT THIS JUNCTURE AS THE MAGNITUDE AND DEPTH OF THE COLD POOL RMNS QNABLE. SEASONAL TEMPERATURES AND DRY WX ARE EXPECTED TO QUICKLY RTN THOUGH AS SW FLOW RESUMES WED AND CONTS THROUGH THE BALANCE OF THE PERIOD. && .AVIATION /12Z FRIDAY THROUGH TUESDAY/... RECENT RADAR AND SURFACE DATA...COUPLED WITH RECENT RAP AND WRF- NMM MODEL OUTPUT...SHOWS SURGES OF RAIN...ASSOCIATED WITH LOW PRESSURE CENTERS MOVING NORTHEASTWARD ALONG THE I-70 STATIONARY FRONT...WILL CONTINUE TO MOVE NORTHEASTWARD ACROSS THE UPPER OHIO VALLEY TODAY INTO FRIDAY. AS RAIN-MOISTENED SURFACE LAYER SATURATES..CONDITIONS WILL LOWER TO MAINLY IFR BY 14Z...AND PERHAPS LIFR TONIGHT. SURFACE WINDS WILL BE MAINLY FROM THE SOUTH AT NO MORE THAN 10 KTS. .OUTLOOK.../SATURDAY NIGHT THROUGH TUESDAY/... FREQUENT IFR RESTRICTIONS DUE TO RAIN FOG AND STRATUS WILL CONTINUE INTO TUESDAY DUE TO A SERIES OF LOW PRESSURE SYSTEMS MOVING EASTWARD ALONG THE STALLED FRONT. && .PBZ WATCHES/WARNINGS/ADVISORIES... MD...NONE. OH...NONE. PA...NONE. WV...NONE. && $$
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
436 AM EST FRI DEC 7 2012 .SYNOPSIS... A STATIONARY FRONT DRAPED OVER THE OHIO VALLEY WILL BE THE FOCUS FOR PERIODIC RAIN INTO EARLY NEXT WEEK. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... RAIN CONTINUES TO MOVE EASTWARD ALONG FRONTAL BOUNDARY WHICH IS DRAPED OVER THE UPPER OHIO VALLEY. RAIN IS DEVELOPING ALONG THE SFC BOUNDARY...BUT AHEAD OF AN UPPER LEVEL WAVE WHICH WILL MOVE THROUGH W PA THIS MORNING. ADDITIONALLY...A LOW LEVEL JET HAS DEVELOPED TO THE SOUTH OF THE FRONT AND WILL CONTINUE TO PUMP MOISTURE NORTHWARD INTO THE BOUNDARY. EVEN AT THIS POINT...THERE STILL REMAIN DIFFERENCES IN MODEL SOLUTIONS WITH THE POSITION OF THE FRONT AND WHEN AND WHERE THE RAIN WILL FALL. WILL FIND COMMON GROUND AND STICK CLOSE TO 21Z SREF...WHICH IS PROVIDING A "HAPPY MEDIUM" BETWEEN THE DIFFERING SOLUTIONS. THERE WILL BE A SERIES OF UPPER LEVEL WAVES THAT WILL MOVE THROUGH TODAY...KEEPING WIDESPREAD SHOWERS IN THE FORECAST. WITH THE SURGE OF WARMER AIR IN THE LOWEST LEVELS...TEMPS ACROSS MUCH OF THE REGION WILL BE ABOVE NORMAL. && .SHORT TERM /6 PM THIS EVENING THROUGH SUNDAY/... MILD AND WET WEA WL DOMINATE THE SHORT TERM PD AS A SERIES OF DISTURBANCES TRIGGER WARM...MOIST ADVCTN AND PCPN AS THEY MOVE ALONG A NEAR-STATIONARY FRONT PROJECTED OVR THE UPR OH VALLEY REGION. BREAKS IN THE PCPN CAN BE EXPECTED WITH PASSAGE OF THE INDIVIDUAL SHORTWAVES. WARM TEMPS WERE FORECAST USING A MIX OF SREF/MAV NUMBERS. && .LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/... CLOUDS AND WET WEATHER CONTINUE INTO EARLY NEXT WEEK. SHORTWAVE THAT IS PROJECTED ACRS THE GREAT LAKES ON MONDAY INTO TUESDAY IS FORECAST TO PUSH THE FRONT SUFFICIENTLY EWD TO END THE WET SPELL. COLD ADVCTN IN THE WAKE OF THE FRONT WITH UPSLOPE/LAKE ENHANCEMENT MAY SPPRT SOME SNOW SHOWERS FOR TUE AND TUE NGT...BUT DO NOT FORESEE MUCH ACCUM AT THIS JUNCTURE AS THE MAGNITUDE AND DEPTH OF THE COLD POOL RMNS QNABLE. SEASONAL TEMPERATURES AND DRY WX ARE EXPECTED TO QUICKLY RTN THOUGH AS SW FLOW RESUMES WED AND CONTS THROUGH THE BALANCE OF THE PERIOD. && .AVIATION /10Z FRIDAY THROUGH TUESDAY/... RECENT RADAR AND SURFACE DATA...COUPLED WITH RECENT RAP AND WRF- NMM MODEL OUTPUT...SHOWS THE INITIAL SURGE OF RAIN ALONG THE DEVELOPING STATIONARY FRONT NEAR THE I-70 CORRIDOR WILL CONTINUE TO SPREAD NORTHEASTWARD ACROSS THE UPPER OHIO VALLEY. THIS HAS CAUSED CONDITIONS TO LOWER TO MAINLY MVFR. AS SURFACE LAYER SATURATES..CONDITIONS WILL LOWER TO MAINLY IFR BY 14Z. WRF-NMM AND SREF MODEL OUTPUT SHOW THERE WILL BE ADDITIONAL SURGES OF IFR RAIN TONIGHT AND SATURDAY...AS LOW PRESSURE WAVES MOVE EASTWARD ALONG THE STATIONARY FRONT. SURFACE WINDS WILL BE MAINLY FROM THE SOUTH AT NO MORE THAN 10 KTS. .OUTLOOK.../SATURDAY NIGHT THROUGH TUESDAY/... FREQUENT IFR RESTRICTIONS DUE TO RAIN FOG AND STRATUS WILL CONTINUE INTO TUESDAY DUE TO A SERIES OF LOW PRESSURE SYSTEMS MOVING EASTWARD ALONG THE STALLED FRONT. && .PBZ WATCHES/WARNINGS/ADVISORIES... MD...NONE. OH...NONE. PA...NONE. WV...NONE. && $$
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
741 PM EST SAT DEC 8 2012 .UPDATE... ISSUED AT 739 PM EST SAT DEC 8 2012 WITH MOCLR SKIES OVER THE W HALF OF UPR MI UNDER SFC RDG AXIS/PWAT 0.18 INCH AS OBSVD ON THE 00Z GRB RAOB...SFC TEMPS HAVE ALREADY REACHED FCST MINS EARLY THIS EVNG. SO TENDED TO LOWER THESE NUMBERS A COUPLE OF DEGREES OVER THE W HALF BEFORE INCRSG HI CLDS FM THE SW ARRIVE BY MIDNGT AND AT LEAST STEADY OFF THE TEMP DROP. && .SHORT TERM...(THIS EVENING THROUGH SUNDAY) ISSUED AT 340 PM EST SAT DEC 8 2012 HIGH PRESSURE IS CURRENTLY LOCATED IN MANITOBA AND ONTARIO...WITH A RIDGE STRETCHING SOUTHEAST INTO WESTERN UPPER MI AND WI. LIGHT NORTHWEST FLOW...WITH RUC ANALYZED H850 OF -10 TO -12C...HAS LED TO LAKE EFFECT CLOUDS AND LIGHT SNOW SHOWERS THROUGH THIS AFTERNOON IN THE TRADITIONAL NORTHWEST FLOW LOCATIONS. UPSTREAM...PV ANOMALY IN SRN SD AND NW NEBRASKA WILL SHIFT ENE TONIGHT AND INTO MN BY 12Z SUNDAY...WITH THE SURFACE LOW FOLLOWING SUIT. THIS ANOMALY WILL SHIFT NORTHEAST THROUGH WESTERN UPPER MICHIGAN THROUGH THE DAY ON SUNDAY AND BE WEAKENING DUE TO INFLUENCE OF SECOND ANOMALY ENTERING NORTHERN MN AND THE SOUTHERN WAVE BECOMING MORE DOMINATE AS IT DIVES SOUTHEAST THROUGH THE CENTRAL ROCKIES DURING THE DAY ON SUNDAY. THIS...COMBINED WITH A STRENGTHENING JET OVER THE OHIO VALLEY ON SUNDAY...WILL ALLOW A SECONDARY LOW TO DEVELOP IN THE OHIO VALLEY REGION DURING THE DAY AND PRODUCE A BROAD AREA OF LOW PRESSURE WHICH TRANSITIONS THE LOW OVER OUR AREA TO A TROUGH. STILL DIFFERENCES IN THE MODELS...BOTH RUN-TO-RUN AND BETWEEN MODELS...WITH THE POTENTIAL WEAKENING/SPEED OF THE PV ANOMALY AND THE LOCATION OF THE ASSOCIATED SURFACE TROUGH HEADING INTO SUNDAY AFTERNOON/EVENING. LATEST TRENDS IN THE MODELS ARE FOR A SLOWER MOVEMENT OF THE PV ANOMALY THROUGH UPPER MICHIGAN ON SUNDAY...WHICH KEEPS THE SURFACE TROUGH AXIS OVER NORTHERN/CENTRAL WISCONSIN. TONIGHT...THE HIGH PRESSURE RIDGE EXITING TO THE NORTHEAST WILL PRODUCE QUIET WEATHER BEFORE THE SYSTEM. UPSTREAM DRYING THIS AFTERNOON HAS ATE AWAY AT SOME OF THE LAKE EFFECT CLOUDS OVER THE WEST AND ONCE DAYTIME HEATING IS LOST...EXPECT THE SAME TO OCCUR OVER THE INTERIOR LOCATIONS THIS EVENING. THIS CLEARING WILL MAKE FOR TRICKY LOW TEMPERATURES TONIGHT AND FOLLOWED THE PREVIOUS SHIFT BY TRENDED THEM DOWN A LITTLE MORE AS PWATS 65 PERCENT OF NORMAL AND THERE ARE LIGHT WINDS. WENT WITH LOWS IN UPPER TEENS...BUT BASED OFF HOW QUICKLY TEMPS FELL THIS MORNING IN CLEARING AREAS...THAT MAY NOT BE COLD ENOUGH. OTHERWISE...MID/HIGH LEVEL CLOUDS WILL BE ON THE INCREASE FROM THE SOUTHWEST WITH THE APPROACHING SYSTEM. SUNDAY...PRECIPITATION BUILDS IN FROM SOUTHWEST TO NORTHEAST THROUGH THE DAY. STARTING BETWEEN 12-15Z NEAR KIWD...LATE MORNING OR EARLY AFTERNOON OVER THE CENTRAL...AND MID/LATE AFTERNOON OVER THE EAST. WITH THE LATEST SLOWER TRENDS...HAVE DELAYED THE START A COUPLE OF HOURS FROM THE PREVIOUS SHIFT. PLENTY OF COLD AIR ALOFT...SO EXPECT PRECIPITATION TO BE AS ALL SNOW. AS FOR FORCING...BEST MID LEVEL WAA IS FOCUSED OVER THE SOUTH CENTRAL AND NEAR LAKE MICHIGAN THROUGH THE DAY. THIS LINES UP WITH WEAK FGEN BETWEEN H850-650 OVER THE AREA FOR THE AFTERNOON...BUT SEEMS TO FOCUS OVER THE SOUTHEAST HALF OF THE CWA LATE IN THE AFTERNOON. IN ADDITION...BROAD 280-290K ISENTROPIC ASCENT WILL SPREAD OVER THE CWA DURING THE DAY. FINALLY...H850 TEMPS AROUND -9C SHOULD FAVOR SOME LAKE ENHANCEMENT FOR THE KEWEENAW AND ALSO FOR LOCATIONS NEAR LAKE MICHIGAN FAVORED BY ESE WINDS. WITH THE SLIGHT DELAY WITH THE SLOWER ARRIVAL OF THE PV ANOMALY AND SURFACE TROUGH BEING A LITTLE FARTHER SOUTH...BEST PRECIPITATION STRADDLES THE SHORT/LONG TERM TRANSITION. ALL IN ALL...MODEL QPF FOR SUNDAY INTO SUNDAY NIGHT WITH THE SYNOPTIC FEATURES IS IN THE 0.25-0.4IN FOR MOST AREAS AND WHEN COMBINED WITH A SNOW RATIO AROUND 13-15 TO 1...WOULD PUT 3 TO 6 INCHES OF SYNOPTIC SNOW OVER THE AREA THROUGH SUNDAY EVENING. OUTSIDE OF ANY LAKE ENHANCEMENT...THE HIGHEST AMOUNTS SHOULD LINE UP ALONG THE WISCONSIN BORDER WITH THE SLIGHT SOUTH SHIFT OF THE SURFACE TROUGH. THE LONG TERM DISCUSSION WILL COVER THE BULK OF THE HEADLINES...BUT DID DROP THE WATCH OVER THE WESTERN COUNTIES AND HAVE STARTED A LONGER PERIOD ADVISORY FROM WEST TO EAST THROUGH THE DAY ON SUNDAY. .LONG TERM...(SUNDAY NIGHT THROUGH SATURDAY) ISSUED AT 340 PM EST SAT DEC 8 2012 MAIN CONCERN IS WITH SNOWFALL FORECAST FOR THE FIRST 24 HOURS OF THE LONG TERM. SUN NIGHT/MON...IN GENERAL...MODELS ARE IN GOOD AGREEMENT...BUT THERE ARE SUBTLE VARIATIONS AT SMALLER SCALES THAT BECOME MAGNIFIED IN THE SNOWFALL FORECAST. THE DIFFICULTY AND UNCERTAINTY IS DUE TO THE FACT THAT THE SYSTEM OVER THE REGION SUN NIGHT WILL BE MERGING WITH A SRN STREAM SYSTEM OVER THE OHIO VALLEY...PLUS THE FACT THAT MODELS HAVE A HARD TIME CONSISTENTLY HANDLING THE PV ANOMALIES THAT WILL DRIVE A GOOD PORTS OF THE SNOWFALL WITH THIS SYSTEM. LATEST RUNS OF THE GFS/NAM/REGIONAL GEM/REGIONAL WRF ARE NOW IN BETTER AGREEMENT IN BRINGING THE WEAKENING PRIMARY PV ANOMALY FROM NW WI AT 00Z MON TO CENTRAL UPPER MI AROUND 06Z MON...THEN SHEARING IT OUT AND PUSHING IT NORTHEAST BY 12Z MON. MEANWHILE...THE SECONDARY PV ANOMALY WILL ROTATE INTO CENTRAL/SRN WI...FARTHER S THAN PREVIOUS RUNS OF THE MODELS. THE TIMING/LOCATION OF THE PV ANOMALIES IS CONSISTENT WITH THE OVERALL TREND OVER THE LAST FEW RUNS OF THE MODELS IN SLOWING THE SYSTEM DOWN AND MOVING IT FARTHER S. THE RESULTING SFC TROUGH LOOKS TO STAY TO THE S OF THE CWA OVER CENTRAL/NRN WI. LOW LEVEL FLOW WILL GENERALLY BE ELY AT 00Z MON WITH 850MB TEMPS AROUND -9C. BY 06Z MON...LOW LEVEL WINDS BACK TO MORE ENE...THEN TO NNE BY 12Z MON AS 850MB TEMPS FALL TO -11C. SYNOPTIC SNOWFALL AMOUNTS WILL BE HIGHEST OVER THE SRN HALF OF UPPER MI SUN NIGHT...BUT THAT SHOULD BE OFFSET SOME BY UPSLOPE FLOW IN SOME NRN LOCATIONS...PARTICULARLY NCENTRAL UPPER MI AND THE KEWEENAW...THEN OVER THE WRN U.P. LATER SUN NIGHT. 850MB TEMPS FALL ANOTHER COUPLE OF DEGREES THROUGH THE DAY MON WHILE FLOW BECOMES INCREASING ANTICYCLONIC AS THE SFC TROUGH MOVES QUICKLY E AND A RIDGE MOVES OVER WRN LAKE SUPERIOR BY 00Z TUE. THUS...EXPECT LES FROM NNW WINDS MON MORNING...DIMINISHING THROUGH MON EVENING. WITH THIS TYPE OF SYSTEM THERE IS INHERENT UNCERTAINTY THAT WILL PROBABLY NOT BE RESOLVED UNTIL THE SYSTEM IS ON THE DOORSTEP OF THE CWA...SO CONFIDENCE IN SNOWFALL AMOUNTS IS STILL SOMEWHAT LIMITED. STORM TOTAL SNOWFALL AMOUNTS OF 3 TO 6 INCHES IS EXPECTED...WITH SOME LOCALLY HIGHER AMOUNTS POSSIBLE IN THE HIGHER TERRAIN OF WRN GOGEBIC/ONTONAGON COUNTIES AND NW MARQUETTE/NE BARAGA COUNTIES. DECIDED IN COORDINATION WITH SHORT TERM SHIFT TO ISSUE WINTER WX ADVISORIES OVER THE ENTIRE CWA. COULD SEE SOME LOCATIONS GO SLIGHTLY ABOVE ADVISORY CRITERIA...BUT NOT CONFIDENT ENOUGH IN THAT TO JUSTIFY WARNING. ALSO...THE TIME THAT THE HEAVIEST SNOW WILL FALL /SUN EVENING AND EARLY SUN NIGHT/ IS NOT A HIGH IMPACT TIME TRAVEL WISE...PLUS THE FACT THAT THE STORM TOTAL WILL OCCUR OVER 24 HOURS OR MORE. ALSO DECIDED ON THE ADVISORY WITH THE IDEA THAT IT WOULD BE EASIER TO UPGRADE TO A WARNING IF NEEDED THAN HAVE TO CANCEL WARNINGS AND ISSUE AN ADVISORY IF THE BORDERLINE WARNING AMOUNTS DO NOT OCCUR...WHICH WOULD LEAD TO A MISSED EVENT FOR VERIFICATION...SORT OF THE PATH OF LEAST REGRET. A VERY WEAK SHORTWAVE TROUGH MOVES ACROSS THE AREA TUE INTO TUE NIGHT...BRINGING SE FLOW OFF LAKE MICHIGAN FROM 12Z TUE INTO WED. THIS SHOULD LEAD TO LES OFF LAKE MI INTO ERN UPPER MI...ESPECIALLY SERN SCHOOLCRAFT COUNTY. INVERSION HEIGHTS SHOULD BE AROUND 10KFT ACCORDING TO THE NAM/GFS WITH UNIDIRECTIONAL WINDS. THE RESULTING LES BAND SHOULD BE A LARGER MORE DOMINANT ONE...BUT SHOULD ALSO NOT STAY IN ONE PLACE TOO LONG AS WINDS STEADILY VEER. EVEN SO...MAY END UP BEING CLOSE TO ADVISORY AMOUNTS. WINDS WILL BECOME WLY ENOUGH BEHIND THE TROUGH BY 06Z WED TO BRING LES TO NW UPPER MI...BUT WINDS QUICKLY BECOME ANTICYCLONIC BY 12Z WED AS A SFC RIDGE MOVES TO WRN LAKE SUPERIOR...SO LIGHTER SNOW AMOUNTS ARE EXPECTED THERE. A SLIGHTLY STRONGER SYSTEM WILL MOVE N OF THE AREA THU AND DRAW WARMER TEMPS IN THE CWA...BUT NO SIGNIFICANT PRECIP IS EXPECTED. HIGHS IN THE MID TO UPPER 30S SEEMS REASONABLE. PRETTY QUIET AFTER THAT UNTIL MODELS INDICATE A MUCH STRONGER LOW PRESSURE SYSTEM MOVING NEARBY ON SAT. MODELS ARE IN GOOD AGREEMENT FOR HOW FAR OUT THE SYSTEM IS...SO WILL USE CONSENSUS OF MODELS FOR THE FORECAST PAST TUE. && .AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SUNDAY EVENING) ISSUED AT 622 PM EST SAT DEC 8 2012 ALTHOUGH SOME INTERVALS OF MVFR CIGS ARE POSSIBLE TNGT...EXPECT PREDOMINANT VFR CONDITIONS THRU 12Z AT ALL THE TAF SITES WITH RDG OF HI PRES/AXIS OF LLVL DRY AIR DOMINATING. THEN ON SUN...APRCH OF LO PRES WL BRING SN LOWER CIGS/VSBYS SW-NE TO UPR MI. ALTHOUGH SAW IS FARTHER TO THE NE...UPSLOPE ESE WIND MIGHT RESULT IN AN EARLIER ARRIVAL OF THE PCPN/MVFR CIGS. BY LATE IN THE AFTN...CONDITIONS SHOULD DETERIORATE TO IFR AND POSSIBLY LIFR AT ALL 3 LOCATIONS. && .MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE) ISSUED AT 340 PM EST SAT DEC 8 2012 AN AREA OF LOW PRESSURE MOVING OUT OF SOUTHWEST SOUTH DAKOTA WILL ENTER MN TOMORROW MORNING AND THEN MERGE WITH A LOW DEVELOPING IN THE GREAT LAKES TO LEAVE A TROUGH OVER NORTHERN WISCONSIN. THIS TROUGH WILL INCREASE WINDS OUT OF THE EAST AND THEN NORTHEAST DIRECTION SUNDAY INTO SUNDAY NIGHT. AT THIS TIME...THINKING WINDS WILL BE IN THE 20-30KT RANGE...ALTHOUGH THERE COULD BE A FEW GALE FORCE GUSTS TO 35KTS OVER THE WEST AS THE TROUGH SHARPENS LATE SUNDAY NIGHT. BEHIND THIS FEATURE...A SERIES OF WEAK RIDGES AND TROUGHS WILL AFFECT LAKE SUPERIOR DURING THE REST OF THE WORK WEEK AND KEEP WINDS BELOW 25KTS. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... WINTER WEATHER ADVISORY FROM 3 PM SUNDAY TO 7 AM EST MONDAY FOR MIZ006-007-013-014-085. WINTER WEATHER ADVISORY FROM 10 AM EST /9 AM CST/ SUNDAY TO 7 AM EST /6 AM CST/ MONDAY FOR MIZ001-003-004-010-084. WINTER WEATHER ADVISORY FROM 1 PM SUNDAY TO 1 PM EST MONDAY FOR MIZ005. WINTER WEATHER ADVISORY FROM 7 AM EST /6 AM CST/ SUNDAY TO 5 PM EST /4 PM CST/ MONDAY FOR MIZ002-009. WINTER WEATHER ADVISORY FROM 9 AM SUNDAY TO 3 AM CST MONDAY FOR MIZ011-012. LAKE SUPERIOR... NONE. LAKE MICHIGAN... NONE. && $$ UPDATE...KC SHORT TERM...SRF LONG TERM...TITUS AVIATION...KC MARINE...SRF
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
624 PM EST SAT DEC 8 2012 .SHORT TERM...(THIS EVENING THROUGH SUNDAY) ISSUED AT 340 PM EST SAT DEC 8 2012 HIGH PRESSURE IS CURRENTLY LOCATED IN MANITOBA AND ONTARIO...WITH A RIDGE STRETCHING SOUTHEAST INTO WESTERN UPPER MI AND WI. LIGHT NORTHWEST FLOW...WITH RUC ANALYZED H850 OF -10 TO -12C...HAS LED TO LAKE EFFECT CLOUDS AND LIGHT SNOW SHOWERS THROUGH THIS AFTERNOON IN THE TRADITIONAL NORTHWEST FLOW LOCATIONS. UPSTREAM...PV ANOMALY IN SRN SD AND NW NEBRASKA WILL SHIFT ENE TONIGHT AND INTO MN BY 12Z SUNDAY...WITH THE SURFACE LOW FOLLOWING SUIT. THIS ANOMALY WILL SHIFT NORTHEAST THROUGH WESTERN UPPER MICHIGAN THROUGH THE DAY ON SUNDAY AND BE WEAKENING DUE TO INFLUENCE OF SECOND ANOMALY ENTERING NORTHERN MN AND THE SOUTHERN WAVE BECOMING MORE DOMINATE AS IT DIVES SOUTHEAST THROUGH THE CENTRAL ROCKIES DURING THE DAY ON SUNDAY. THIS...COMBINED WITH A STRENGTHENING JET OVER THE OHIO VALLEY ON SUNDAY...WILL ALLOW A SECONDARY LOW TO DEVELOP IN THE OHIO VALLEY REGION DURING THE DAY AND PRODUCE A BROAD AREA OF LOW PRESSURE WHICH TRANSITIONS THE LOW OVER OUR AREA TO A TROUGH. STILL DIFFERENCES IN THE MODELS...BOTH RUN-TO-RUN AND BETWEEN MODELS...WITH THE POTENTIAL WEAKENING/SPEED OF THE PV ANOMALY AND THE LOCATION OF THE ASSOCIATED SURFACE TROUGH HEADING INTO SUNDAY AFTERNOON/EVENING. LATEST TRENDS IN THE MODELS ARE FOR A SLOWER MOVEMENT OF THE PV ANOMALY THROUGH UPPER MICHIGAN ON SUNDAY...WHICH KEEPS THE SURFACE TROUGH AXIS OVER NORTHERN/CENTRAL WISCONSIN. TONIGHT...THE HIGH PRESSURE RIDGE EXITING TO THE NORTHEAST WILL PRODUCE QUIET WEATHER BEFORE THE SYSTEM. UPSTREAM DRYING THIS AFTERNOON HAS ATE AWAY AT SOME OF THE LAKE EFFECT CLOUDS OVER THE WEST AND ONCE DAYTIME HEATING IS LOST...EXPECT THE SAME TO OCCUR OVER THE INTERIOR LOCATIONS THIS EVENING. THIS CLEARING WILL MAKE FOR TRICKY LOW TEMPERATURES TONIGHT AND FOLLOWED THE PREVIOUS SHIFT BY TRENDED THEM DOWN A LITTLE MORE AS PWATS 65 PERCENT OF NORMAL AND THERE ARE LIGHT WINDS. WENT WITH LOWS IN UPPER TEENS...BUT BASED OFF HOW QUICKLY TEMPS FELL THIS MORNING IN CLEARING AREAS...THAT MAY NOT BE COLD ENOUGH. OTHERWISE...MID/HIGH LEVEL CLOUDS WILL BE ON THE INCREASE FROM THE SOUTHWEST WITH THE APPROACHING SYSTEM. SUNDAY...PRECIPITATION BUILDS IN FROM SOUTHWEST TO NORTHEAST THROUGH THE DAY. STARTING BETWEEN 12-15Z NEAR KIWD...LATE MORNING OR EARLY AFTERNOON OVER THE CENTRAL...AND MID/LATE AFTERNOON OVER THE EAST. WITH THE LATEST SLOWER TRENDS...HAVE DELAYED THE START A COUPLE OF HOURS FROM THE PREVIOUS SHIFT. PLENTY OF COLD AIR ALOFT...SO EXPECT PRECIPITATION TO BE AS ALL SNOW. AS FOR FORCING...BEST MID LEVEL WAA IS FOCUSED OVER THE SOUTH CENTRAL AND NEAR LAKE MICHIGAN THROUGH THE DAY. THIS LINES UP WITH WEAK FGEN BETWEEN H850-650 OVER THE AREA FOR THE AFTERNOON...BUT SEEMS TO FOCUS OVER THE SOUTHEAST HALF OF THE CWA LATE IN THE AFTERNOON. IN ADDITION...BROAD 280-290K ISENTROPIC ASCENT WILL SPREAD OVER THE CWA DURING THE DAY. FINALLY...H850 TEMPS AROUND -9C SHOULD FAVOR SOME LAKE ENHANCEMENT FOR THE KEWEENAW AND ALSO FOR LOCATIONS NEAR LAKE MICHIGAN FAVORED BY ESE WINDS. WITH THE SLIGHT DELAY WITH THE SLOWER ARRIVAL OF THE PV ANOMALY AND SURFACE TROUGH BEING A LITTLE FARTHER SOUTH...BEST PRECIPITATION STRADDLES THE SHORT/LONG TERM TRANSITION. ALL IN ALL...MODEL QPF FOR SUNDAY INTO SUNDAY NIGHT WITH THE SYNOPTIC FEATURES IS IN THE 0.25-0.4IN FOR MOST AREAS AND WHEN COMBINED WITH A SNOW RATIO AROUND 13-15 TO 1...WOULD PUT 3 TO 6 INCHES OF SYNOPTIC SNOW OVER THE AREA THROUGH SUNDAY EVENING. OUTSIDE OF ANY LAKE ENHANCEMENT...THE HIGHEST AMOUNTS SHOULD LINE UP ALONG THE WISCONSIN BORDER WITH THE SLIGHT SOUTH SHIFT OF THE SURFACE TROUGH. THE LONG TERM DISCUSSION WILL COVER THE BULK OF THE HEADLINES...BUT DID DROP THE WATCH OVER THE WESTERN COUNTIES AND HAVE STARTED A LONGER PERIOD ADVISORY FROM WEST TO EAST THROUGH THE DAY ON SUNDAY. .LONG TERM...(SUNDAY NIGHT THROUGH SATURDAY) ISSUED AT 340 PM EST SAT DEC 8 2012 MAIN CONCERN IS WITH SNOWFALL FORECAST FOR THE FIRST 24 HOURS OF THE LONG TERM. SUN NIGHT/MON...IN GENERAL...MODELS ARE IN GOOD AGREEMENT...BUT THERE ARE SUBTLE VARIATIONS AT SMALLER SCALES THAT BECOME MAGNIFIED IN THE SNOWFALL FORECAST. THE DIFFICULTY AND UNCERTAINTY IS DUE TO THE FACT THAT THE SYSTEM OVER THE REGION SUN NIGHT WILL BE MERGING WITH A SRN STREAM SYSTEM OVER THE OHIO VALLEY...PLUS THE FACT THAT MODELS HAVE A HARD TIME CONSISTENTLY HANDLING THE PV ANOMALIES THAT WILL DRIVE A GOOD PORTS OF THE SNOWFALL WITH THIS SYSTEM. LATEST RUNS OF THE GFS/NAM/REGIONAL GEM/REGIONAL WRF ARE NOW IN BETTER AGREEMENT IN BRINGING THE WEAKENING PRIMARY PV ANOMALY FROM NW WI AT 00Z MON TO CENTRAL UPPER MI AROUND 06Z MON...THEN SHEARING IT OUT AND PUSHING IT NORTHEAST BY 12Z MON. MEANWHILE...THE SECONDARY PV ANOMALY WILL ROTATE INTO CENTRAL/SRN WI...FARTHER S THAN PREVIOUS RUNS OF THE MODELS. THE TIMING/LOCATION OF THE PV ANOMALIES IS CONSISTENT WITH THE OVERALL TREND OVER THE LAST FEW RUNS OF THE MODELS IN SLOWING THE SYSTEM DOWN AND MOVING IT FARTHER S. THE RESULTING SFC TROUGH LOOKS TO STAY TO THE S OF THE CWA OVER CENTRAL/NRN WI. LOW LEVEL FLOW WILL GENERALLY BE ELY AT 00Z MON WITH 850MB TEMPS AROUND -9C. BY 06Z MON...LOW LEVEL WINDS BACK TO MORE ENE...THEN TO NNE BY 12Z MON AS 850MB TEMPS FALL TO -11C. SYNOPTIC SNOWFALL AMOUNTS WILL BE HIGHEST OVER THE SRN HALF OF UPPER MI SUN NIGHT...BUT THAT SHOULD BE OFFSET SOME BY UPSLOPE FLOW IN SOME NRN LOCATIONS...PARTICULARLY NCENTRAL UPPER MI AND THE KEWEENAW...THEN OVER THE WRN U.P. LATER SUN NIGHT. 850MB TEMPS FALL ANOTHER COUPLE OF DEGREES THROUGH THE DAY MON WHILE FLOW BECOMES INCREASING ANTICYCLONIC AS THE SFC TROUGH MOVES QUICKLY E AND A RIDGE MOVES OVER WRN LAKE SUPERIOR BY 00Z TUE. THUS...EXPECT LES FROM NNW WINDS MON MORNING...DIMINISHING THROUGH MON EVENING. WITH THIS TYPE OF SYSTEM THERE IS INHERENT UNCERTAINTY THAT WILL PROBABLY NOT BE RESOLVED UNTIL THE SYSTEM IS ON THE DOORSTEP OF THE CWA...SO CONFIDENCE IN SNOWFALL AMOUNTS IS STILL SOMEWHAT LIMITED. STORM TOTAL SNOWFALL AMOUNTS OF 3 TO 6 INCHES IS EXPECTED...WITH SOME LOCALLY HIGHER AMOUNTS POSSIBLE IN THE HIGHER TERRAIN OF WRN GOGEBIC/ONTONAGON COUNTIES AND NW MARQUETTE/NE BARAGA COUNTIES. DECIDED IN COORDINATION WITH SHORT TERM SHIFT TO ISSUE WINTER WX ADVISORIES OVER THE ENTIRE CWA. COULD SEE SOME LOCATIONS GO SLIGHTLY ABOVE ADVISORY CRITERIA...BUT NOT CONFIDENT ENOUGH IN THAT TO JUSTIFY WARNING. ALSO...THE TIME THAT THE HEAVIEST SNOW WILL FALL /SUN EVENING AND EARLY SUN NIGHT/ IS NOT A HIGH IMPACT TIME TRAVEL WISE...PLUS THE FACT THAT THE STORM TOTAL WILL OCCUR OVER 24 HOURS OR MORE. ALSO DECIDED ON THE ADVISORY WITH THE IDEA THAT IT WOULD BE EASIER TO UPGRADE TO A WARNING IF NEEDED THAN HAVE TO CANCEL WARNINGS AND ISSUE AN ADVISORY IF THE BORDERLINE WARNING AMOUNTS DO NOT OCCUR...WHICH WOULD LEAD TO A MISSED EVENT FOR VERIFICATION...SORT OF THE PATH OF LEAST REGRET. A VERY WEAK SHORTWAVE TROUGH MOVES ACROSS THE AREA TUE INTO TUE NIGHT...BRINGING SE FLOW OFF LAKE MICHIGAN FROM 12Z TUE INTO WED. THIS SHOULD LEAD TO LES OFF LAKE MI INTO ERN UPPER MI...ESPECIALLY SERN SCHOOLCRAFT COUNTY. INVERSION HEIGHTS SHOULD BE AROUND 10KFT ACCORDING TO THE NAM/GFS WITH UNIDIRECTIONAL WINDS. THE RESULTING LES BAND SHOULD BE A LARGER MORE DOMINANT ONE...BUT SHOULD ALSO NOT STAY IN ONE PLACE TOO LONG AS WINDS STEADILY VEER. EVEN SO...MAY END UP BEING CLOSE TO ADVISORY AMOUNTS. WINDS WILL BECOME WLY ENOUGH BEHIND THE TROUGH BY 06Z WED TO BRING LES TO NW UPPER MI...BUT WINDS QUICKLY BECOME ANTICYCLONIC BY 12Z WED AS A SFC RIDGE MOVES TO WRN LAKE SUPERIOR...SO LIGHTER SNOW AMOUNTS ARE EXPECTED THERE. A SLIGHTLY STRONGER SYSTEM WILL MOVE N OF THE AREA THU AND DRAW WARMER TEMPS IN THE CWA...BUT NO SIGNIFICANT PRECIP IS EXPECTED. HIGHS IN THE MID TO UPPER 30S SEEMS REASONABLE. PRETTY QUIET AFTER THAT UNTIL MODELS INDICATE A MUCH STRONGER LOW PRESSURE SYSTEM MOVING NEARBY ON SAT. MODELS ARE IN GOOD AGREEMENT FOR HOW FAR OUT THE SYSTEM IS...SO WILL USE CONSENSUS OF MODELS FOR THE FORECAST PAST TUE. && .AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SUNDAY EVENING) ISSUED AT 622 PM EST SAT DEC 8 2012 ALTHOUGH SOME INTERVALS OF MVFR CIGS ARE POSSIBLE TNGT...EXPECT PREDOMINANT VFR CONDITIONS THRU 12Z AT ALL THE TAF SITES WITH RDG OF HI PRES/AXIS OF LLVL DRY AIR DOMINATING. THEN ON SUN...APRCH OF LO PRES WL BRING SN LOWER CIGS/VSBYS SW-NE TO UPR MI. ALTHOUGH SAW IS FARTHER TO THE NE...UPSLOPE ESE WIND MIGHT RESULT IN AN EARLIER ARRIVAL OF THE PCPN/MVFR CIGS. BY LATE IN THE AFTN...CONDITIONS SHOULD DETERIORATE TO IFR AND POSSIBLY LIFR AT ALL 3 LOCATIONS. && .MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE) ISSUED AT 340 PM EST SAT DEC 8 2012 AN AREA OF LOW PRESSURE MOVING OUT OF SOUTHWEST SOUTH DAKOTA WILL ENTER MN TOMORROW MORNING AND THEN MERGE WITH A LOW DEVELOPING IN THE GREAT LAKES TO LEAVE A TROUGH OVER NORTHERN WISCONSIN. THIS TROUGH WILL INCREASE WINDS OUT OF THE EAST AND THEN NORTHEAST DIRECTION SUNDAY INTO SUNDAY NIGHT. AT THIS TIME...THINKING WINDS WILL BE IN THE 20-30KT RANGE...ALTHOUGH THERE COULD BE A FEW GALE FORCE GUSTS TO 35KTS OVER THE WEST AS THE TROUGH SHARPENS LATE SUNDAY NIGHT. BEHIND THIS FEATURE...A SERIES OF WEAK RIDGES AND TROUGHS WILL AFFECT LAKE SUPERIOR DURING THE REST OF THE WORK WEEK AND KEEP WINDS BELOW 25KTS. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... WINTER WEATHER ADVISORY FROM 3 PM SUNDAY TO 7 AM EST MONDAY FOR MIZ006-007-013-014-085. WINTER WEATHER ADVISORY FROM 10 AM EST /9 AM CST/ SUNDAY TO 7 AM EST /6 AM CST/ MONDAY FOR MIZ001-003-004-010-084. WINTER WEATHER ADVISORY FROM 1 PM SUNDAY TO 1 PM EST MONDAY FOR MIZ005. WINTER WEATHER ADVISORY FROM 7 AM EST /6 AM CST/ SUNDAY TO 5 PM EST /4 PM CST/ MONDAY FOR MIZ002-009. WINTER WEATHER ADVISORY FROM 9 AM SUNDAY TO 3 AM CST MONDAY FOR MIZ011-012. LAKE SUPERIOR... NONE. LAKE MICHIGAN... NONE. && $$ SHORT TERM...SRF LONG TERM...TITUS AVIATION...KC MARINE...SRF
AREA FORECAST DISCUSSION
NWS TWIN CITIES/CHANHASSEN MN
646 PM CST SAT DEC 8 2012 .UPDATE... 00Z AVIATION DISCUSSION ADDED BELOW. && .PREV DISCUSSION... /ISSUED 447 PM CST SAT DEC 8 2012/ ..DANGEROUS WINTER STORM TO IMPACT THE UPPER MISSISSIPPI VALLEY TONIGHT THROUGH SUNDAY NIGHT... SHORT TERM...TONIGHT THROUGH TUESDAY NIGHT. LOW PRESSURE LOCATED NEAR VALENTINE NEBRASKA LATE THIS AFTERNOON WILL TRACK ALMOST DUE EAST TONIGHT AND SUNDAY...TRACKING ROUGHLY ALONG THE I-90 CORRIDOR. THIS IS A SIGNIFICANT SHIFT SOUTH FROM WHAT MODELS WERE SHOWING YESTERDAY...WITH THE NAM REMAINING THE LONE NORTHERN OUTLIER TRACKING IT ACROSS THE TWIN CITIES METRO. IN ADDITION...QPF HAS INCREASED MARKEDLY FROM 00Z RUNS AND NOW AVERAGES BETWEEN A HALF AND AT LEAST THREE QUARTERS OF AN INCH FROM WILLMAR TO NEAR LADYSMITH...OR JUST NORTH OF THE METRO. ELSEWHERE...QPF AVERAGES 0.3 TO 0.5 INCHES. THE 18Z GFS IS COMING IN SURPRISINGLY HIGH AT NEARLY ONE INCH AND AGAIN JUST A BIT FURTHER SOUTH FROM PREVIOUS RUNS...NOW THROUGH THE METRO. EVEN THE EC WHICH WAS THE DRY OUTLIER YESTERDAY IS SHOWING AT LEAST 0.6 INCHES OVER MUCH OF THE CENTRAL AREAS. MODEL INCONSISTENCY FROM RUN TO RUN SHOULD NOW BE ABOUT COMPLETE...LEAVING A VERY HIGH PROBABILITY FOR A MAJOR WINTER STORM ACROSS MUCH OF THE AREA TONIGHT INTO SUNDAY EVENING. THE ARC OF SNOW EXPECTED TO PROPAGATE INTO WESTERN MINNESOTA DURING THE NEXT FEW HOURS IS EXPANDING IN SIZE AND PRODUCING MODERATE TO HEAVY SNOWFALL RATES WITHIN EMBEDDED BANDS. WITH TIME...THIS AREA OF SNOW WILL EXPAND WITH WIDESPREAD MODERATE TO HEAVY SNOW EXPECTED TO SPREAD EAST ACROSS THE AREA LATER THIS EVENING AND OVERNIGHT. FRONTOGENESIS WITHIN THE DENDRITIC GROWTH ZONE IS RATHER IMPRESSIVE SO EMBEDDED BANDS OF VERY HEAVY SNOW WITH GREATER THAN ONE INCH HOURLY RATES ARE POSSIBLE THROUGH SUNDAY MORNING. BECAUSE THE TRACK OF THE LOW WILL BE CONFINED TO ABOUT I-90...THE THREAT FOR DRY SLOTTING INTO THE SOUTHERN AREAS IS A BIT LOWER ALTHOUGH STILL POSSIBLE FOR THE SOUTHERN TWO TIERS OF MN COUNTIES COME SUNDAY MORNING. STORM TRACK HAS SLOWED A BIT AS WELL...THUS DEFORMATION SNOW WILL HELP PILE ON THE INCHES A BIT LONGER THAN ANTICIPATED YESTERDAY. OCCASIONAL SNOW OR SNOW SHOWERS ARE EXPECTED THROUGH AT LEAST EARLY SUNDAY AFTERNOON AND POSSIBLY THROUGH THE EVENING OVER WESTERN WISCONSIN. PREDICTED SNOWFALL AMOUNTS MAY BE CONSERVATIVE IF THE HIGHER QPF DEPICTIONS PAN OUT...BUT STILL EXPECTING 6 TO 9 INCHES ACROSS CENTRAL MN AND WESTERN WISCONSIN...AND 3 TO 5 INCHES NEAR THE IOWA BORDER. COULD SEE SOME ISOLATED TOTALS EXCEED 9 OR 10 INCHES IN LOCALLY FAVORED BANDING AREAS. THEREFORE...EXPANDED THE WINTER STORM WARNING SOUTH TO ABOUT A LINE FROM REDWOOD FALLS...TO RED WING..AND EAU CLAIRE WITH A WINTER WEATHER ADVISORY SOUTH OF THAT TO THE IOWA BORDER. THESE HEADLINES DEAL WITH SNOWFALL TOTALS ONLY. THE BIG CHANGE TO THIS FORECAST PACKAGE WAS TO ISSUE A BLIZZARD WARNING FROM LATE SUNDAY MORNING THROUGH SUNDAY EVENING WEST OF A LINE FROM ALEXANDRIA TO WILLMAR AND MANKATO. MODELS HAVE BEEN CONSISTENT IN SHOWING POTENTIAL FOR 40 KT WINDS WITHIN THE MIXED LAYER BEHIND THE SYSTEM AND THINK GUSTS TO AT LEAST 35 KTS WILL BE FREQUENT. COUPLE THAT WITH FRESHLY FALLEN SNOW AND POTENTIALLY ADDITIONAL LIGHT SNOW...CONFIDENCE HAS INCREASED THAT BLIZZARD CONDITIONS WILL BE COMMON WITH NEAR ZERO VISIBILITIES IN OPEN AREAS SUNDAY AFTERNOON AND EARLY EVENING /ESPECIALLY IF GUSTS EXCEED 45 MPH/. TEMPERATURES WILL PLUMMET BELOW ZERO SUNDAY EVENING AS WELL...THREATENING THE LIVES OF ANY STUCK TRAVELERS. KEPT THE BLIZZARD WARNING CONFINED TO AREAS WITH A HIGH LIKELIHOOD OF AT LEAST 4 INCHES OF SNOW WHICH IS GENERALLY NEEDED FOR CONSIDERABLE BLOWING AND DRIFTING. THE SYSTEM WILL PULL OUT SUNDAY NIGHT AS THE RIDGE QUICKLY BUILDS INTO THE WEST. SOME SNOW IS STILL POSSIBLE OVER WRN WI IN CYCLONIC FLOW...BUT CLEARING SKIES WILL ALLOW FOR A BITTER COLD NIGHT WITH LOWS IN THE TEENS BELOW OVER WRN MN AND NEAR ZERO AS FAR EAST AS I-35. WINDS SHOULD REMAIN ELEVATED ENOUGH TO BRING WIND CHILL VALUES DOWN INTO THE 20S AND POSSIBLY LOW 30S BELOW NEAR THE SOUTH DAKOTA BORDER...WITH TEENS BELOW TO I-35. WIND CHILL ADVISORIES WILL BE NEEDED AFTER THE OTHER WINTER HEADLINES EXPIRE. WILL REMAIN COLD DESPITE SUNSHINE ON MONDAY UNDER THE RIDGE AXIS...BUT RETURN FLOW MONDAY EVENING SHOULD KEEP TEMPS STEADY OR SLOWLY RISE OVERNIGHT. A WEAK SYSTEM PASSING THROUGH THE UPPER MISSISSIPPI VALLEY TUESDAY COULD BRING A LITTLE LIGHT SNOW OR FLURRIES WITH NO ACCUMULATIONS ARE EXPECTED. LONG TERM...WEDNESDAY THROUGH SATURDAY. UPPER LEVEL RIDGING WILL BE IN PLACE ACROSS THE GULF OF ALASKA BY MIDWEEK...WITH A DEEP TROUGH DIGGING DOWN THE WEST COAST. SOUTHWEST FLOW WILL STREAM ACROSS THE CENTRAL CONUS...WITH WARM AIR ADVECTION SPREADING OVERHEAD ALLOWING HIGH TEMPS TO MAKE A RUN AT THE THAWING MARK FOR BOTH WEDNESDAY AND THURSDAY. BY FRIDAY A WELL ESTABLISHED EAST/WEST TEMPERATURE GRADIENT WILL BE IN PLACE OVER THE UPPER MIDWEST...AND THE AFOREMENTIONED WEST COAST TROUGH WILL MOVE INLAND OVER THE FOUR CORNERS REGION. THIS WILL BE THE MAIN PLAYER IN THE WEEKEND WEATHER AS BOTH THE GFS AND ECMWF 08.12 EJECT THIS WAVE TOWARDS THE GREAT LAKES REGION. THIS PV ANOMALY WILL ACT ON THE LOW LEVEL TEMPERATURE GRADIENT AND CAUSE A SURFACE CYCLONE TO DEVELOP AND TRACK SOUTH AND EAST OF THE CWA. THIS WOULD PUT CENTRAL MINNESOTA AND WESTERN WISCONSIN IN A FAVORABLE REGION FOR ANOTHER POTENTIAL WEEKEND SNOW STORM. FORECAST SOUNDINGS AND NORTH/SOUTH CROSS SECTIONS VIA THE GFS SHOW A WARM LAYER CENTERED AROUND H850 WITH THE 0C LINE EXTENDING AS FAR NORTH AS THE METRO AREA. THEREFORE HAVE INCLUDED THE CHANCE OF MIXED PRECIP FOR SATURDAY MORNING ACROSS THE SOUTHEAST HALF OF THE CWA WITH THE INITIAL SURGE OF LOW LEVEL THETA_E ADVECTION...AND THEN TRANSITION TO ALL SNOW BY THE AFTERNOON. ALSO INCREASED POPS ABOVE GUIDANCE GIVEN THE REMARKABLE AGREEMENT BY THE LONG RANGE MODELS. && .AVIATION.../06Z TAF ISSUANCE/ WINTER STORM STILL ON TRACK TO IMPACT ALL TERMINALS THIS PERIOD...WITH VERY POOR WEATHER CONDITIONS EXPECTED. TIMED SNOW IN BASED ON THE LOCAL WRF AND HIRES-ARW FORECAST...WHICH RESULTED IN A SLIGHT DELAY IN SNOW ONSET. LOOKING AT OBS IN SODAK...WITHIN AN HOUR OF ONSET OF SNOW...VIS WILL DROP TO 1/2SM OR LESS...SO QUICKLY DROPPED CONDITIONS IN TAFS. THE RAP SHOWS HOURLY SNOWFALL ACCUMS OF AN 1"+ PER HOUR TONIGHT INTO THE MORNING...AND IF THIS IS TO BE THE CASE...THEN PERIODS OF 1/4SM OR LESS VIS IN HEAVY SNOW WILL BE LIKELY WITHIN PERIOD WHERE 1/2SM PREVAILING CONDS ARE MENTIONED. SFC LOW NOW SOUTH OF PIERRE...AND BY THE AFTERNOON IT SHOULD BE PASSING VERY NEAR MSP. EXPECT HEAVIEST SNOW OUT AHEAD OF THE LOW...WITH DEFORMATION BAND PROLONGING REDUCED CONDITIONS AT AXN/STC. SNOW TOTALS AT ALL TERMINALS LOOKS TO BE IN THE 5 TO 8 INCH RANGE. FOR WINDS...STRONG CAA LOOKS TO PROMOTE GUSTS WELL OVER 30KTS AT AXN/RWF AFTER 18Z...WHICH WILL LEAD TO REDUCED VSBY ISSUES WITH BLSN THERE. CONFIDENCE DOES DECREASE DURING THE DAY TOMORROW...WITH PRIMARY AMOUNT OF TIME SPENT PINNING DOWN TIMING OF THE ONSET OF SN. KMSP...SIGNIFICANT IMPACTS EXPECTED WITH WINTER STORM THIS PERIOD. IN ALL LIKELIHOOD...SNOW RATES WILL BE IN EXCESS OF 3/4 OF AN INCH AN HOUR...SO AN AWW WILL BE NEEDED AT SOME POINT AROUND 6Z. AS SFC LOW NEARS THE FIELD...MAY SEE A WINDOW BETWEEN 15Z AND 20Z WHERE SNOW CUTS OFF AND VIS INCREASES...BEFORE WRAP AROUND SNOW AND STRONG NW WINDS SEND VIS BACK DOWN IN -SN AND BLSN. /OUTLOOK FOR KMSP/ MON...MVFR/IFR CIGS POSSIBLE EARLY. THEN VFR. WINDS WNW AT 10G15KTS. TUE...MVFR/IFR CIGS POSSIBLE. WINDS SW AT 10G15KTS. WED...VFR. WINDS SE AT 10KTS. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...WINTER WEATHER ADVISORY FROM MIDNIGHT TONIGHT TO MIDNIGHT CST SUNDAY NIGHT FOR BLUE EARTH-FARIBAULT-FREEBORN-GOODHUE-LE SUEUR-RICE-STEELE-WASECA. WINTER STORM WARNING UNTIL 11 AM CST SUNDAY FOR CHIPPEWA-DOUGLAS- KANDIYOHI-LAC QUI PARLE-POPE-RENVILLE-SIBLEY-STEVENS-SWIFT- YELLOW MEDICINE. BLIZZARD WARNING FROM 11 AM SUNDAY TO MIDNIGHT CST SUNDAY NIGHT FOR BROWN-CHIPPEWA-DOUGLAS-KANDIYOHI-LAC QUI PARLE-NICOLLET- POPE-REDWOOD-RENVILLE-SIBLEY-STEVENS-SWIFT-YELLOW MEDICINE. WINTER STORM WARNING UNTIL MIDNIGHT CST SUNDAY NIGHT FOR BENTON- CHISAGO-ISANTI-KANABEC-MCLEOD-MEEKER-MILLE LACS-MORRISON- SHERBURNE-STEARNS-TODD-WRIGHT. WINTER STORM WARNING FROM MIDNIGHT TONIGHT TO MIDNIGHT CST SUNDAY NIGHT FOR ANOKA-CARVER-DAKOTA-HENNEPIN-RAMSEY-SCOTT- WASHINGTON. WINTER WEATHER ADVISORY UNTIL MIDNIGHT CST SUNDAY NIGHT FOR MARTIN-WATONWAN. WINTER WEATHER ADVISORY UNTIL 11 AM CST SUNDAY FOR BROWN- NICOLLET-REDWOOD. WI...WINTER STORM WARNING FROM MIDNIGHT TONIGHT TO MIDNIGHT CST SUNDAY NIGHT FOR BARRON-CHIPPEWA-DUNN-EAU CLAIRE-PEPIN- PIERCE-POLK-RUSK-ST. CROIX. && $$ BORGHOFF/MPG
AREA FORECAST DISCUSSION
NWS TWIN CITIES/CHANHASSEN MN
1207 PM CST FRI DEC 7 2012 .UPDATED FOR 18Z AVIATION AND WINTER STORM WATCH... .DISCUSSION... EXPANDED THE WINTER STORM WATCH SOUTHWARD A FEW ROWS OF COUNTIES GIVEN CONTINUED TRENDS OF 12Z MODELS. THINK THE 12Z NAM QPF IS A BIT TOO BULLISH AND LEANING TOWARD THE GFS. GIVEN THAT...EXPANDED IT SOUTHWARD TO AREAS WITH ROUGHLY 0.4 INCH QPF WHICH WOULD TRANSLATE TO AROUND 5 INCHES OF SNOW. IN ADDITION...WITH WINDS INCREASING SUNDAY...BLOWING SNOW WILL BECOME A PROBLEM PARTICULARLY OVER THE WESTERN HALF OF MINNESOTA. STILL WILL SEE A DRY SLOT PUNCH INTO THE SOUTHWEST CWA NEAR MANKATO SUNDAY MORNING WHICH WOULD LIMIT ACCUMULATION TO PERHAPS 4 INCHES...BUT WINDS WILL BE MAXIMIZED IN THAT AREA WHICH WOULD BRING A LARGER BLOWING SNOW THREAT. SOMETHING INTERESTING OF NOTE...A WELL-PERFORMING EXPERIMENTAL MODEL FAILS TO PRODUCE A LOW WITHIN THE INVERTED TROUGH OVER CENTRAL MN WHICH RESULTS IN A DEFORMATION BAND FURTHER SOUTH FROM WILLMAR TO MSP TO EAU CLAIRE. WHILE THIS IS AN OUTLIER SCENARIO...IT STILL ADDS TO THE POTENTIAL FOR SIGNIFICANT ACCUMULATIONS FURTHER SOUTH.-BORGHOFF /PREVIOUS DISCUSSION ISSUED AT 411 AM CST FRI DEC 07 2012/ PLENTY OF CONCERNS THIS MORNING WITH TWO WEATHER SYSTEMS MOVING THROUGH FROM TODAY THROUGH SUNDAY. THE FIRST IS A MID LEVEL LOW APPROACHING CENTRAL SD EARLY THIS MORNING. THIS FEATURE IS PROGGED TO MOVE EAST AND PASS ACROSS SOUTHERN MN THIS EVENING. ACCOMPANYING THE LOW IS A FAIRLY STRONG BAND OF FRONTOGENESIS AND OMEGA AT -15 DEG C. THE PROBLEM IS THE FORCING AND MODEL QPF...ESPECIALLY FROM THE GFS...ARE NOT IN SYNC. IN ADDITION...THERE IS GOOD CONSENSUS ON A PV MAX MOVING ACROSS SOUTHERN MN ALONG WITH A 120M HEIGHT FALL CENTER. RAP GUIDANCE POINTS TO SW AND SOUTH CENTRAL MN FOR THE MOST QPF WHICH AGREES MUCH BETTER WITH THE FORCING. PRECIP AMOUNTS ARE IN THE .10 TO .25 INCH RANGE WITH THE MOST IN OUR FAR SW MN COUNTIES. THE NAM AND GFS ARE SIMILAR BUT MUCH FARTHER NORTH. FOLLOWING THE FORCING SEEMS TO BE THE MOST CORRECT THING TO DO AND THIS WOULD PLACE NEAR ADVISORY SNOWFALL OVER SW AND PARTS OF SOUTH CENTRAL MN DURING THE AFTERNOON AND EVENING. THE TREND ON THIS WEATHER SYSTEM OVER THE PAST TWO NIGHTS HAS BEEN GETTING STRONGER AND TAKING LONGER TO WEAKEN DURING THE OVERNIGHT HOURS. THERE IS ALSO QUITE THE SNOW BAND IN WESTERN/CENTRAL SD NORTH OF I-90. THEREFORE..USED FORECASTER DISCRETION AND ISSUED A WINTER WEATHER ADVISORY FROM WEST CENTRAL INTO SOUTH CENTRAL MN FOR THIS AFTERNOON AND EVENING. WE CURRENTLY HAVE 2 TO 2.5 INCHES IN THE ADVISORY AREA...BUT CONCERNED AMOUNTS MAY BE HIGHER IN THE BAND OF MID LEVEL -FN VECTOR DIVERGENCE. STILL HAVE SNOW SPREADING ACROSS THE TWIN CITIES DURING THE AFTERNOON AND EVENING WITH AMOUNTS UP TO ONE INCH. THE SECOND CONCERN IS A MUCH STRONGER LOW PRESSURE SYSTEM FORECAST ACROSS THE REGION SATURDAY NIGHT AND SUNDAY. NAM/GFS/ECMWF STILL SHOW A MID LEVEL LOW PASSING ACROSS CENTRAL MN AND NORTHERN WI DURING THIS PERIOD. A BAND OF WAA SNOW WILL PRECEDE THE LOW WITH DEFORMATION SNOW CONTINUING FROM WEST CENTRAL MN INTO THE ARROWHEAD ON SUNDAY. THE TOP THREE CIPS ANALOGS ALL HAD 6+ INCHES OF SNOW ACROSS CENTRAL MN WITH A FOOT OR MORE FOR THE NORTH. THE TREND ON THIS WEATHER SYSTEM OVER THE PAST FEW NIGHT IS FARTHER SOUTH WITH THE SFC/MID LEVEL LOW PRESSURE. THIS SYSTEM IS ACCOMPANIED BY A VERY STRONG PV BOOT SATURDAY NIGHT AND SUNDAY POINTING INTO WEST CENTRAL AND NORTHERN AREAS OF MN. THE SURFACE GRADIENT THAT DEVELOPS OVER WESTERN MN SUNDAY MORNING IS ALARMING. BUFKIT NAM/GFS PROFILE DATA FOR KMOX SHOW WINDS JUST OFF THE SURFACE IN THE 25-29 KNOT RANGE WITH TOP OF THE CHANNEL IN THE 38-43 KNOT RANGE. DEPENDING ON HOW MUCH SNOW FALLS...AND IF THE WINDS VERIFY...THIS COULD END UP BEING A BLIZZARD FOR PARTS OF THE WEST ON SUNDAY. TEMPERATURES WILL ALSO BE STEADY OR FALLING IN THE TEENS WITH BELOW ZERO TEMPERATURES EXPECTED SUNDAY NIGHT. AFTER QUITE A BIT OF COLLABORATION WITH KDLH...KARX AND KABR...WE FELT IT WAS PRUDENT TO ISSUE A WINTER STORM WATCH FOR SATURDAY NIGHT AND SUNDAY. CURRENT SNOW ACCUMULATION GRIDS ARE IN THE 5 TO 7 INCH RANGE ACROSS CENTRAL MN AND PARTS OF WEST CENTRAL WI. CURRENTLY HAVE 4 TO 5 INCHES FOR THE TWIN CITIES. LITTLE TIME SPENT ON LONGER TERM GRIDS WITH THE CRH EXTEND ACCEPTED. A QUICK GLANCE FOR THE MONDAY THROUGH THURSDAY PERIOD SHOWS ONLY WEAK WEATHER SYSTEM PASSING BY AND MAINLY TO THE NORTH. TEMPERATURES BELOW NORMAL FOR MUCH OF NEXT WEEK. && .AVIATION.../18Z TAF ISSUANCE/ MAIN CONCERN WILL BE THE ONSET...INTENSITY..AND DURATION OF SNOWFALL THAT WILL MOVE EASTWARD ACROSS THE FORECAST AREA TODAY. AS OF LATE MORNING IFR CONDITIONS WERE ONGOING ACROSS SOUTHWEST MINNESOTA. EXPECT MAINLY 1 TO 2SM VISBYS...WITH A HALF MILE POSSIBLE AT TIMES. WINDS WILL BE LIGHT THROUGH THE OVERNIGHT HOURS...AND GRADUALLY TAKE ON A SOUTHERLY DIRECTION BY LATE SATURDAY MORNING. KMSP... MOVED UP THE ONSET TIME OF THE SNOWFALL AT KMSP GIVEN THE RECENT TRENDS DEPICTED ON RADAR. TOTAL SNOWFALL SHOULD BE AROUND AN INCH...AND NOT ANTICIPATING ANY RATES OVER 3/4 IN/HR. LOW CLOUDS WILL ACCOMPANY THE SNOWFALL...AND SHOULD DROP BELOW 1700 FEET FOR THE MAJORITY OF THE OVERNIGHT HOURS BEFORE IMPROVING SATURDAY MORNING. /OUTLOOK FOR KMSP/ SAT NIGHT...IFR AND -SN WITH POSSIBLE LIFR AND +SN. WINDS SE AT 10KTS. SUN...IFR AND -SN WITH POSSIBLE LIFR AND +SN EARLY. WINDS SE AT 05KTS BECOMING NW AT 20G30KTS AFTER 18Z. MON...MVFR WITH -SHSN EARLY...THEN VFR. WINDS W AT 10G15KTS. TUE...MVFR WITH -SN POSSIBLE. WINDS W AT 10G15KTS. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...WINTER WEATHER ADVISORY UNTIL MIDNIGHT CST TONIGHT FOR BLUE EARTH-BROWN-CHIPPEWA-FARIBAULT-LAC QUI PARLE-LE SUEUR- MARTIN-NICOLLET-REDWOOD-RENVILLE-SIBLEY-WASECA-WATONWAN- YELLOW MEDICINE. WINTER STORM WATCH FROM SATURDAY EVENING THROUGH SUNDAY AFTERNOON FOR ANOKA-BENTON-BROWN-CARVER-CHIPPEWA-CHISAGO- DAKOTA-DOUGLAS-GOODHUE-HENNEPIN-ISANTI-KANABEC-KANDIYOHI- LAC QUI PARLE-LE SUEUR-MCLEOD-MEEKER-MILLE LACS-MORRISON- NICOLLET-POPE-RAMSEY-REDWOOD-RENVILLE-RICE-SCOTT-SHERBURNE- SIBLEY-STEARNS-STEVENS-SWIFT-TODD-WASHINGTON-WRIGHT-YELLOW MEDICINE. WI...WINTER STORM WATCH FROM LATE SATURDAY NIGHT THROUGH SUNDAY EVENING FOR BARRON-CHIPPEWA-DUNN-EAU CLAIRE-PEPIN-PIERCE- POLK-RUSK-ST. CROIX. && $$ BB/RAH/JRB
AREA FORECAST DISCUSSION...UPDATED
NWS TWIN CITIES/CHANHASSEN MN
1105 AM CST FRI DEC 7 2012 .UPDATE... EXPANDED THE WINTER STORM WATCH SOUTHWARD A FEW ROWS OF COUNTIES GIVEN CONTINUED TRENDS OF 12Z MODELS. THINK THE 12Z NAM QPF IS A BIT TOO BULLISH AND LEANING TOWARD THE GFS. GIVEN THAT...EXPANDED IT SOUTHWARD TO AREAS WITH ROUGHLY 0.4 INCH QPF WHICH WOULD TRANSLATE TO AROUND 5 INCHES OF SNOW. IN ADDITION...WITH WINDS INCREASING SUNDAY...BLOWING SNOW WILL BECOME A PROBLEM PARTICULARLY OVER THE WESTERN HALF OF MINNESOTA. STILL WILL SEE A DRY SLOT PUNCH INTO THE SOUTHWEST CWA NEAR MANKATO SUNDAY MORNING WHICH WOULD LIMIT ACCUMULATION TO PERHAPS 4 INCHES...BUT WINDS WILL BE MAXIMIZED IN THAT AREA WHICH WOULD BRING A LARGER BLOWING SNOW THREAT. SOMETHING INTERESTING OF NOTE...A WELL-PERFORMING EXPERIMENTAL MODEL FAILS TO PRODUCE A LOW WITHIN THE INVERTED TROUGH OVER CENTRAL MN WHICH RESULTS IN A DEFORMATION BAND FURTHER SOUTH FROM WILLMAR TO MSP TO EAU CLAIRE. WHILE THIS IS AN OUTLIER SCENARIO...IT STILL ADDS TO THE POTENTIAL FOR SIGNIFICANT ACCUMULATIONS FURTHER SOUTH. BORGHOFF && .AVIATION... /12Z TAF ISSUANCE/ SOME MINOR ADJUSTMENTS TO GOING FORECAST. MAY SEE A SLOWER START TIME FARTHER EAST...BUT STILL DROP CEILINGS TO MVFR OVER THE REGION...MOST LIKELY IFR VSBYS. KRWF MAY SEE IFR CONDITIONS INTO HE AFTERNOON AS HEAVIER SNOW BAND FORECAST ALONG THE MINNESOTA RIVER VALLEY...PERHAPS INTO SOUTHERN METRO BY LATE AFTERNOON. WILL HAVE TO MONITOR BAND AS IT WORKS OVER THE DAKOTAS THIS MORNING. SNOW COMING IN LATE AFTERNOON/EVENING OVER EASTERN TAF SITES...SHOULD TAPER FARTHER EAST AS WAVE MOVES THROUGH DRY AIR AND WEAKENS A BIT. SNOW SHOULD END TO THE WEST EARLY EVENING AND AFTER 06Z TO THE EAST...WITH MVFR CEILINGS REMAINING FOR NOW AHEAD OF THE NEXT STRONGER SYSTEM FOR SATURDAY. LIGHT WINDS BECOMING MORE NORTHEAST/EAST AHEAD OF WAVE AND EVENTUALLY SOUTHEAST TO SOUTH ON SATURDAY. KMSP...ONLY MINOR ADJUSTMENT TO TIMING OF SNOW. SHOULD MOVE IN BY 22Z AND EXIT AFTER 06Z2. IFR VSBYS IN HEAVIER SNOW THIS EVENING...THEN IMPROVING LATE. MAYBE AN INCH ACCUMULATION. LIGHT WINDS BECOMING NORTHEAST TO EAST DURING THE DAY AND SOUTHEAST INTO SATURDAY. /OUTLOOK FOR KMSP/ SAT...MVFR CIGS ENDING IN THE MORNING...THEN VFR. MVFR/IFR CIGS/VIS DEVELOPING OVERNIGHT WITH SN. WINDS SE AT 10KTS. SUN...SN ENDING IN THE AFTERNOON...2-4 IN POSSIBLE. MVFR/IFR CIGS/VIS IN MORNING. MVFR CIGS AFTERNOON. WINDS BCMG NW 20G30KTS. MON...MVFR CIGS EARLY...BECOMING VFR IN AFTERNOON. WINDS NW 15KTS IN MORNING...BCMG SW AT 5 KTS IN AFTERNOON. && .PREV DISCUSSION... /ISSUED 545 AM CST FRI DEC 7 2012/ PLENTY OF CONCERNS THIS MORNING WITH TWO WEATHER SYSTEMS MOVING THROUGH FROM TODAY THROUGH SUNDAY. THE FIRST IS A MID LEVEL LOW APPROACHING CENTRAL SD EARLY THIS MORNING. THIS FEATURE IS PROGGED TO MOVE EAST AND PASS ACROSS SOUTHERN MN THIS EVENING. ACCOMPANYING THE LOW IS A FAIRLY STRONG BAND OF FRONTOGENESIS AND OMEGA AT -15 DEG C. THE PROBLEM IS THE FORCING AND MODEL QPF...ESPECIALLY FROM THE GFS...ARE NOT IN SYNC. IN ADDITION...THERE IS GOOD CONSENSUS ON A PV MAX MOVING ACROSS SOUTHERN MN ALONG WITH A 120M HEIGHT FALL CENTER. RAP GUIDANCE POINTS TO SW AND SOUTH CENTRAL MN FOR THE MOST QPF WHICH AGREES MUCH BETTER WITH THE FORCING. PRECIP AMOUNTS ARE IN THE .10 TO .25 INCH RANGE WITH THE MOST IN OUR FAR SW MN COUNTIES. THE NAM AND GFS ARE SIMILAR BUT MUCH FARTHER NORTH. FOLLOWING THE FORCING SEEMS TO BE THE MOST CORRECT THING TO DO AND THIS WOULD PLACE NEAR ADVISORY SNOWFALL OVER SW AND PARTS OF SOUTH CENTRAL MN DURING THE AFTERNOON AND EVENING. THE TREND ON THIS WEATHER SYSTEM OVER THE PAST TWO NIGHTS HAS BEEN GETTING STRONGER AND TAKING LONGER TO WEAKEN DURING THE OVERNIGHT HOURS. THERE IS ALSO QUITE THE SNOW BAND IN WESTERN/CENTRAL SD NORTH OF I-90. THEREFORE..USED FORECASTER DISCRETION AND ISSUED A WINTER WEATHER ADVISORY FROM WEST CENTRAL INTO SOUTH CENTRAL MN FOR THIS AFTERNOON AND EVENING. WE CURRENTLY HAVE 2 TO 2.5 INCHES IN THE ADVISORY AREA...BUT CONCERNED AMOUNTS MAY BE HIGHER IN THE BAND OF MID LEVEL -FN VECTOR DIVERGENCE. STILL HAVE SNOW SPREADING ACROSS THE TWIN CITIES DURING THE AFTERNOON AND EVENING WITH AMOUNTS UP TO ONE INCH. THE SECOND CONCERN IS A MUCH STRONGER LOW PRESSURE SYSTEM FORECAST ACROSS THE REGION SATURDAY NIGHT AND SUNDAY. NAM/GFS/ECMWF STILL SHOW A MID LEVEL LOW PASSING ACROSS CENTRAL MN AND NORTHERN WI DURING THIS PERIOD. A BAND OF WAA SNOW WILL PRECEDE THE LOW WITH DEFORMATION SNOW CONTINUING FROM WEST CENTRAL MN INTO THE ARROWHEAD ON SUNDAY. THE TOP THREE CIPS ANALOGS ALL HAD 6+ INCHES OF SNOW ACROSS CENTRAL MN WITH A FOOT OR MORE FOR THE NORTH. THE TREND ON THIS WEATHER SYSTEM OVER THE PAST FEW NIGHT IS FARTHER SOUTH WITH THE SFC/MID LEVEL LOW PRESSURE. THIS SYSTEM IS ACCOMPANIED BY A VERY STRONG PV BOOT SATURDAY NIGHT AND SUNDAY POINTING INTO WEST CENTRAL AND NORTHERN AREAS OF MN. THE SURFACE GRADIENT THAT DEVELOPS OVER WESTERN MN SUNDAY MORNING IS ALARMING. BUFKIT NAM/GFS PROFILE DATA FOR KMOX SHOW WINDS JUST OFF THE SURFACE IN THE 25-29 KNOT RANGE WITH TOP OF THE CHANNEL IN THE 38-43 KNOT RANGE. DEPENDING ON HOW MUCH SNOW FALLS...AND IF THE WINDS VERIFY...THIS COULD END UP BEING A BLIZZARD FOR PARTS OF THE WEST ON SUNDAY. TEMPERATURES WILL ALSO BE STEADY OR FALLING IN THE TEENS WITH BELOW ZERO TEMPERATURES EXPECTED SUNDAY NIGHT. AFTER QUITE A BIT OF COLLABORATION WITH KDLH...KARX AND KABR...WE FELT IT WAS PRUDENT TO ISSUE A WINTER STORM WATCH FOR SATURDAY NIGHT AND SUNDAY. CURRENT SNOW ACCUMULATION GRIDS ARE IN THE 5 TO 7 INCH RANGE ACROSS CENTRAL MN AND PARTS OF WEST CENTRAL WI. CURRENTLY HAVE 4 TO 5 INCHES FOR THE TWIN CITIES. LITTLE TIME SPENT ON LONGER TERM GRIDS WITH THE CRH EXTEND ACCEPTED. A QUICK GLANCE FOR THE MONDAY THROUGH THURSDAY PERIOD SHOWS ONLY WEAK WEATHER SYSTEM PASSING BY AND MAINLY TO THE NORTH. TEMPERATURES BELOW NORMAL FOR MUCH OF NEXT WEEK. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...WINTER WEATHER ADVISORY UNTIL MIDNIGHT CST TONIGHT FOR BLUE EARTH-BROWN-CHIPPEWA-FARIBAULT-LAC QUI PARLE-LE SUEUR- MARTIN-NICOLLET-REDWOOD-RENVILLE-SIBLEY-WASECA-WATONWAN- YELLOW MEDICINE. WINTER STORM WATCH FROM SATURDAY EVENING THROUGH SUNDAY AFTERNOON FOR ANOKA-BENTON-BROWN-CARVER-CHIPPEWA-CHISAGO- DAKOTA-DOUGLAS-GOODHUE-HENNEPIN-ISANTI-KANABEC-KANDIYOHI- LAC QUI PARLE-LE SUEUR-MCLEOD-MEEKER-MILLE LACS-MORRISON- NICOLLET-POPE-RAMSEY-REDWOOD-RENVILLE-RICE-SCOTT-SHERBURNE- SIBLEY-STEARNS-STEVENS-SWIFT-TODD-WASHINGTON-WRIGHT-YELLOW MEDICINE. WI...WINTER STORM WATCH FROM LATE SATURDAY NIGHT THROUGH SUNDAY EVENING FOR BARRON-CHIPPEWA-DUNN-EAU CLAIRE-PEPIN-PIERCE- POLK-RUSK-ST. CROIX. && $$ RAH/DWE
AREA FORECAST DISCUSSION
NWS TWIN CITIES/CHANHASSEN MN
545 AM CST FRI DEC 7 2012 .UPDATED FOR THE 12Z AVIATION DISCUSSION BELOW... .DISCUSSION... PLENTY OF CONCERNS THIS MORNING WITH TWO WEATHER SYSTEMS MOVING THROUGH FROM TODAY THROUGH SUNDAY. THE FIRST IS A MID LEVEL LOW APPROACHING CENTRAL SD EARLY THIS MORNING. THIS FEATURE IS PROGGED TO MOVE EAST AND PASS ACROSS SOUTHERN MN THIS EVENING. ACCOMPANYING THE LOW IS A FAIRLY STRONG BAND OF FRONTOGENESIS AND OMEGA AT -15 DEG C. THE PROBLEM IS THE FORCING AND MODEL QPF...ESPECIALLY FROM THE GFS...ARE NOT IN SYNC. IN ADDITION...THERE IS GOOD CONSENSUS ON A PV MAX MOVING ACROSS SOUTHERN MN ALONG WITH A 120M HEIGHT FALL CENTER. RAP GUIDANCE POINTS TO SW AND SOUTH CENTRAL MN FOR THE MOST QPF WHICH AGREES MUCH BETTER WITH THE FORCING. PRECIP AMOUNTS ARE IN THE .10 TO .25 INCH RANGE WITH THE MOST IN OUR FAR SW MN COUNTIES. THE NAM AND GFS ARE SIMILAR BUT MUCH FARTHER NORTH. FOLLOWING THE FORCING SEEMS TO BE THE MOST CORRECT THING TO DO AND THIS WOULD PLACE NEAR ADVISORY SNOWFALL OVER SW AND PARTS OF SOUTH CENTRAL MN DURING THE AFTERNOON AND EVENING. THE TREND ON THIS WEATHER SYSTEM OVER THE PAST TWO NIGHTS HAS BEEN GETTING STRONGER AND TAKING LONGER TO WEAKEN DURING THE OVERNIGHT HOURS. THERE IS ALSO QUITE THE SNOW BAND IN WESTERN/CENTRAL SD NORTH OF I-90. THEREFORE..USED FORECASTER DISCRETION AND ISSUED A WINTER WEATHER ADVISORY FROM WEST CENTRAL INTO SOUTH CENTRAL MN FOR THIS AFTERNOON AND EVENING. WE CURRENTLY HAVE 2 TO 2.5 INCHES IN THE ADVISORY AREA...BUT CONCERNED AMOUNTS MAY BE HIGHER IN THE BAND OF MID LEVEL -FN VECTOR DIVERGENCE. STILL HAVE SNOW SPREADING ACROSS THE TWIN CITIES DURING THE AFTERNOON AND EVENING WITH AMOUNTS UP TO ONE INCH. THE SECOND CONCERN IS A MUCH STRONGER LOW PRESSURE SYSTEM FORECAST ACROSS THE REGION SATURDAY NIGHT AND SUNDAY. NAM/GFS/ECMWF STILL SHOW A MID LEVEL LOW PASSING ACROSS CENTRAL MN AND NORTHERN WI DURING THIS PERIOD. A BAND OF WAA SNOW WILL PRECEDE THE LOW WITH DEFORMATION SNOW CONTINUING FROM WEST CENTRAL MN INTO THE ARROWHEAD ON SUNDAY. THE TOP THREE CIPS ANALOGS ALL HAD 6+ INCHES OF SNOW ACROSS CENTRAL MN WITH A FOOT OR MORE FOR THE NORTH. THE TREND ON THIS WEATHER SYSTEM OVER THE PAST FEW NIGHT IS FARTHER SOUTH WITH THE SFC/MID LEVEL LOW PRESSURE. THIS SYSTEM IS ACCOMPANIED BY A VERY STRONG PV BOOT SATURDAY NIGHT AND SUNDAY POINTING INTO WEST CENTRAL AND NORTHERN AREAS OF MN. THE SURFACE GRADIENT THAT DEVELOPS OVER WESTERN MN SUNDAY MORNING IS ALARMING. BUFKIT NAM/GFS PROFILE DATA FOR KMOX SHOW WINDS JUST OFF THE SURFACE IN THE 25-29 KNOT RANGE WITH TOP OF THE CHANNEL IN THE 38-43 KNOT RANGE. DEPENDING ON HOW MUCH SNOW FALLS...AND IF THE WINDS VERIFY...THIS COULD END UP BEING A BLIZZARD FOR PARTS OF THE WEST ON SUNDAY. TEMPERATURES WILL ALSO BE STEADY OR FALLING IN THE TEENS WITH BELOW ZERO TEMPERATURES EXPECTED SUNDAY NIGHT. AFTER QUITE A BIT OF COLLABORATION WITH KDLH...KARX AND KABR...WE FELT IT WAS PRUDENT TO ISSUE A WINTER STORM WATCH FOR SATURDAY NIGHT AND SUNDAY. CURRENT SNOW ACCUMULATION GRIDS ARE IN THE 5 TO 7 INCH RANGE ACROSS CENTRAL MN AND PARTS OF WEST CENTRAL WI. CURRENTLY HAVE 4 TO 5 INCHES FOR THE TWIN CITIES. LITTLE TIME SPENT ON LONGER TERM GRIDS WITH THE CRH EXTEND ACCEPTED. A QUICK GLANCE FOR THE MONDAY THROUGH THURSDAY PERIOD SHOWS ONLY WEAK WEATHER SYSTEM PASSING BY AND MAINLY TO THE NORTH. TEMPERATURES BELOW NORMAL FOR MUCH OF NEXT WEEK. && .AVIATION... /06Z TAF ISSUANCE/ SOME MINOR ADJUSTMENTS TO GOING FORECAST. MAY SEE A SLOWER START TIME FARTHER EAST...BUT STILL DROP CEILINGS TO MVFR OVER THE REGION...MOST LIKELY IFR VSBYS. KRWF MAY SEE IFR CONDITIONS INTO HE AFTERNOON AS HEAVIER SNOW BAND FORECAST ALONG THE MINNESOTA RIVER VALLEY...PERHAPS INTO SOUTHERN METRO BY LATE AFTERNOON. WILL HAVE TO MONITOR BAND AS IT WORKS OVER THE DAKOTAS THIS MORNING. SNOW COMING IN LATE AFTERNOON/EVENING OVER EASTERN TAF SITES...SHOULD TAPER FARTHER EAST AS WAVE MOVES THROUGH DRY AIR AND WEAKENS A BIT. SNOW SHOULD END TO THE WEST EARLY EVENING AND AFTER 06Z TO THE EAST...WITH MVFR CEILINGS REMAINING FOR NOW AHEAD OF THE NEXT STRONGER SYSTEM FOR SATURDAY. LIGHT WINDS BECOMING MORE NORTHEAST/EAST AHEAD OF WAVE AND EVENTUALLY SOUTHEAST TO SOUTH ON SATURDAY. KMSP...ONLY MINOR ADJUSTMENT TO TIMING OF SNOW. SHOULD MOVE IN BY 22Z AND EXIT AFTER 06Z2. IFR VSBYS IN HEAVIER SNOW THIS EVENING...THEN IMPROVING LATE. MAYBE AN INCH ACCUMULATION. LIGHT WINDS BECOMING NORTHEAST TO EAST DURING THE DAY AND SOUTHEAST INTO SATURDAY. /OUTLOOK FOR KMSP/ SAT...MVFR CIGS ENDING IN THE MORNING...THEN VFR. MVFR/IFR CIGS/VIS DEVELOPING OVERNIGHT WITH SN. WINDS SE AT 10KTS. SUN...SN ENDING IN THE AFTERNOON...2-4 IN POSSIBLE. MVFR/IFR CIGS/VIS IN MORNING. MVFR CIGS AFTERNOON. WINDS BCMG NW 20G30KTS. MON...MVFR CIGS EARLY...BECOMING VFR IN AFTERNOON. WINDS NW 15KTS IN MORNING...BCMG SW AT 5 KTS IN AFTERNOON. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...WINTER WEATHER ADVISORY FROM NOON TODAY TO MIDNIGHT CST TONIGHT FOR BLUE EARTH-BROWN-CHIPPEWA-FARIBAULT-LAC QUI PARLE-LE SUEUR-MARTIN-NICOLLET-REDWOOD-RENVILLE-SIBLEY-WASECA- WATONWAN-YELLOW MEDICINE. WINTER STORM WATCH FROM SATURDAY EVENING THROUGH SUNDAY AFTERNOON FOR ANOKA-BENTON-CHIPPEWA-CHISAGO-DOUGLAS-ISANTI- KANABEC-KANDIYOHI-LAC QUI PARLE-MCLEOD-MEEKER-MILLE LACS- MORRISON-POPE-REDWOOD-RENVILLE-SHERBURNE-STEARNS-STEVENS- SWIFT-TODD-WRIGHT-YELLOW MEDICINE. WI...WINTER STORM WATCH FROM LATE SATURDAY NIGHT THROUGH SUNDAY EVENING FOR BARRON-CHIPPEWA-POLK-RUSK. && $$ RAH/DE
AREA FORECAST DISCUSSION
NWS TWIN CITIES/CHANHASSEN MN
411 AM CST FRI DEC 7 2012 .DISCUSSION... PLENTY OF CONCERNS THIS MORNING WITH TWO WEATHER SYSTEMS MOVING THROUGH FROM TODAY THROUGH SUNDAY. THE FIRST IS A MID LEVEL LOW APPROACHING CENTRAL SD EARLY THIS MORNING. THIS FEATURE IS PROGGED TO MOVE EAST AND PASS ACROSS SOUTHERN MN THIS EVENING. ACCOMPANYING THE LOW IS A FAIRLY STRONG BAND OF FRONTOGENESIS AND OMEGA AT -15 DEG C. THE PROBLEM IS THE FORCING AND MODEL QPF...ESPECIALLY FROM THE GFS...ARE NOT IN SYNC. IN ADDITION...THERE IS GOOD CONSENSUS ON A PV MAX MOVING ACROSS SOUTHERN MN ALONG WITH A 120M HEIGHT FALL CENTER. RAP GUIDANCE POINTS TO SW AND SOUTH CENTRAL MN FOR THE MOST QPF WHICH AGREES MUCH BETTER WITH THE FORCING. PRECIP AMOUNTS ARE IN THE .10 TO .25 INCH RANGE WITH THE MOST IN OUR FAR SW MN COUNTIES. THE NAM AND GFS ARE SIMILAR BUT MUCH FARTHER NORTH. FOLLOWING THE FORCING SEEMS TO BE THE MOST CORRECT THING TO DO AND THIS WOULD PLACE NEAR ADVISORY SNOWFALL OVER SW AND PARTS OF SOUTH CENTRAL MN DURING THE AFTERNOON AND EVENING. THE TREND ON THIS WEATHER SYSTEM OVER THE PAST TWO NIGHTS HAS BEEN GETTING STRONGER AND TAKING LONGER TO WEAKEN DURING THE OVERNIGHT HOURS. THERE IS ALSO QUITE THE SNOW BAND IN WESTERN/CENTRAL SD NORTH OF I-90. THEREFORE..USED FORECASTER DISCRETION AND ISSUED A WINTER WEATHER ADVISORY FROM WEST CENTRAL INTO SOUTH CENTRAL MN FOR THIS AFTERNOON AND EVENING. WE CURRENTLY HAVE 2 TO 2.5 INCHES IN THE ADVISORY AREA...BUT CONCERNED AMOUNTS MAY BE HIGHER IN THE BAND OF MID LEVEL -FN VECTOR DIVERGENCE. STILL HAVE SNOW SPREADING ACROSS THE TWIN CITIES DURING THE AFTERNOON AND EVENING WITH AMOUNTS UP TO ONE INCH. THE SECOND CONCERN IS A MUCH STRONGER LOW PRESSURE SYSTEM FORECAST ACROSS THE REGION SATURDAY NIGHT AND SUNDAY. NAM/GFS/ECMWF STILL SHOW A MID LEVEL LOW PASSING ACROSS CENTRAL MN AND NORTHERN WI DURING THIS PERIOD. A BAND OF WAA SNOW WILL PRECEDE THE LOW WITH DEFORMATION SNOW CONTINUING FROM WEST CENTRAL MN INTO THE ARROWHEAD ON SUNDAY. THE TOP THREE CIPS ANALOGS ALL HAD 6+ INCHES OF SNOW ACROSS CENTRAL MN WITH A FOOT OR MORE FOR THE NORTH. THE TREND ON THIS WEATHER SYSTEM OVER THE PAST FEW NIGHT IS FARTHER SOUTH WITH THE SFC/MID LEVEL LOW PRESSURE. THIS SYSTEM IS ACCOMPANIED BY A VERY STRONG PV BOOT SATURDAY NIGHT AND SUNDAY POINTING INTO WEST CENTRAL AND NORTHERN AREAS OF MN. THE SURFACE GRADIENT THAT DEVELOPS OVER WESTERN MN SUNDAY MORNING IS ALARMING. BUFKIT NAM/GFS PROFILE DATA FOR KMOX SHOW WINDS JUST OFF THE SURFACE IN THE 25-29 KNOT RANGE WITH TOP OF THE CHANNEL IN THE 38-43 KNOT RANGE. DEPENDING ON HOW MUCH SNOW FALLS...AND IF THE WINDS VERIFY...THIS COULD END UP BEING A BLIZZARD FOR PARTS OF THE WEST ON SUNDAY. TEMPERATURES WILL ALSO BE STEADY OR FALLING IN THE TEENS WITH BELOW ZERO TEMPERATURES EXPECTED SUNDAY NIGHT. AFTER QUITE A BIT OF COLLABORATION WITH KDLH...KARX AND KABR...WE FELT IT WAS PRUDENT TO ISSUE A WINTER STORM WATCH FOR SATURDAY NIGHT AND SUNDAY. CURRENT SNOW ACCUMULATION GRIDS ARE IN THE 5 TO 7 INCH RANGE ACROSS CENTRAL MN AND PARTS OF WEST CENTRAL WI. CURRENTLY HAVE 4 TO 5 INCHES FOR THE TWIN CITIES. LITTLE TIME SPENT ON LONGER TERM GRIDS WITH THE CRH EXTEND ACCEPTED. A QUICK GLANCE FOR THE MONDAY THROUGH THURSDAY PERIOD SHOWS ONLY WEAK WEATHER SYSTEM PASSING BY AND MAINLY TO THE NORTH. TEMPERATURES BELOW NORMAL FOR MUCH OF NEXT WEEK. && .AVIATION... /06Z TAF ISSUANCE/ MAIN CHANGE WITH 06Z TAFS...IS THAT 00Z NAM/GFS ALONG WITH LAST FEW RUNS OF THE HRRR IS STARTING TO INCREASE CONFIDENCE IN -SN OCCURRING AT ALL TERMINALS. TIMING IN TAFS STILL LOOKS GOOD AS WELL. GFS/NAM ALONG WITH THE HRRR SEEM TO BE HONING IN ON A BAND OF -SN COMING OUT OF CENTRAL SODAK...THEN DUE EAST ACROSS THE MPX AREA FRI AFTERNOON/EVENING. AXN/STC MAY BE JUST NORTH OF THE HEAVIEST SNOW...BUT A QUICK 1-3 INCHES IS LOOKING MORE PLAUSIBLE FOR RWF AND MSP. FOR WI...MODELS CONTINUE TO SHOW FORCING AND SNOW WANING AS THINGS GET INTO WI...SO LEFT VIS RESTRICTIONS ANT RNH/EAU AT MVFR. CIGS WILL BE SLOW TO DESCEND...BUT BY FRIDAY NIGHT...925-850 RH FROM THE GFS/NAM ALONG WITH SREF PROBS FOR CIGS LESS THAN 3K FT WOULD INDICATE THAT A BAND OF IFR/MVFR MAY GET HUNG UP ACROSS MN...SO DID TREND CIGS DOWNWARD...ESPECIALLY FOR AXN/RWF. KMSP...290/295K ISENTROPIC SFCS ALONG WITH MID-LEVEL FGEN WOULD SAY SNOW COULD START AS EARLY AS 18Z AT MSP...BUT BEST FORCING STILL WAITS UNTIL 00Z TO BRING IN BEST FORCING...SO BROUGHT IN IFR VSBYS THEN. LOOKS LIKE THE EVENING RUSH COULD SEE 1-3 INCHES OF SNOW IF CURRENT GFS/NAM PANS OUT. FOR WINDS...THEY WILL BE LIGHT WITH HIGH PRESSURE SLIDING BY THROUGH THE PERIOD WITH JUST A GRADUAL VEERING OF WINDS FROM NW TO SE THROUGH THE PERIOD. DIRECTIONS LOOK TO CROSS AN 040 DIRECTION AROUND 3Z. /OUTLOOK FOR KMSP/ SAT...MVFR CIGS ENDING MID MORNING...THEN VFR. MVFR/IFR CIGS/VIS DEVELOPING OVERNIGHT WITH SN. WINDS SE AT 10KTS. SUN...SN ENDING IN MORNING...1-3 IN POSSIBLE. MVFR/IFR CIGS/VIS IN MORNING. MVFR CIGS AFTERNOON. WINDS BCMG NW 20G30KTS. MON...MVFR CIGS EARLY...BECOMING VFR IN AFTERNOON. WINDS NW 15KTS IN MORNING...BCMG SW AT 5 KTS IN AFTERNOON. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...WINTER WEATHER ADVISORY FROM NOON TODAY TO MIDNIGHT CST TONIGHT FOR BLUE EARTH-BROWN-CHIPPEWA-FARIBAULT-LAC QUI PARLE-LE SUEUR-MARTIN-NICOLLET-REDWOOD-RENVILLE-SIBLEY-WASECA- WATONWAN-YELLOW MEDICINE. WINTER STORM WATCH FROM SATURDAY EVENING THROUGH SUNDAY AFTERNOON FOR ANOKA-BENTON-CHIPPEWA-CHISAGO-DOUGLAS-ISANTI- KANABEC-KANDIYOHI-LAC QUI PARLE-MCLEOD-MEEKER-MILLE LACS- MORRISON-POPE-REDWOOD-RENVILLE-SHERBURNE-STEARNS-STEVENS- SWIFT-TODD-WRIGHT-YELLOW MEDICINE. WI...WINTER STORM WATCH FROM LATE SATURDAY NIGHT THROUGH SUNDAY EVENING FOR BARRON-CHIPPEWA-POLK-RUSK. && $$ RAH/MPG
AREA FORECAST DISCUSSION
NWS TWIN CITIES/CHANHASSEN MN
1100 PM CST THU DEC 6 2012 .UPDATE... 06Z AVIATION DISCUSSION ADDED BELOW. && .PREV DISCUSSION... /ISSUED 417 PM CST THU DEC 6 2012/ SHORT TERM...TONIGHT THROUGH FRIDAY NIGHT. ZONAL FLOW ACROSS MOST OF THE CONUS HAS LED TO RELATIVELY TRANQUIL WEATHER TODAY...ASIDE FROM A COLD FRONT MOVING ACROSS WRN WI THIS AFTERNOON. THE COLD FRONT IS ASSOCIATED WITH LOW PRESSURE OVER HUDSON BAY WHICH IS PUSHING NORTHEAST FAIRLY RAPIDLY. LOTS OF CLOUDS ARE EMBEDDED WITHIN THE WESTERLY FLOW SO NOT ANTICIPATING THE CLEARING CURRENTLY OVER SRN MN TO LAST MUCH BEYOND EARLY EVENING...ESPECIALLY WITH THE NEXT SHORT WAVE CURRENTLY OVER NORTHWESTERN WASHINGTON STATE MOVING INTO THE NORTHERN PLAINS BY EARLY FRIDAY MORNING. KEPT TEMPS A TOUCH ABOVE MOS CONSENSUS WITH LOWS GENERALLY IN THE LOW TO MID 20S. THE SHORT WAVE WILL CONTINUE HEADING EAST FRIDAY...BUT IT WON/T BEGIN TO REALLY AFFECT THE AREA UNTIL FRIDAY AFTERNOON. MODELS CONTINUE TO SHOW THIS FEATURE WEAKENING AS IT PUSHES INTO SRN MN...WITH QPF RANGING FROM 0.15 INCHES NEAR REDWOOD FALLS TO LESS THAN 0.05 INCHES OVER WRN WI. GOOD LIFT ARRIVES FAIRLY EARLY...BUT CONSIDERABLE DRY AIR IN THE BOUNDARY LAYER WILL INHIBIT MUCH SNOW FROM REACHING THE GROUND UNTIL AFTER 18Z IN SWRN MN AND AFTER 21-00Z ACROSS ERN MN AND FAR WRN WI. THE BEST OVERLAP OF THESE TWO CRITICAL ELEMENTS WILL LAST ABOUT 6 HOURS OVER WRN MN BUT WEAKENING LIFT WITH TIME WILL LEAVE THE EAST /INCLUDING THE TWIN CITIES METRO/ WITH A FEW HOUR WINDOW. UNFORTUNATELY THIS COMES DURING RUSH HOUR...BETWEEN 23-02Z. TOTAL SNOWFALL AMOUNTS WITH THIS FEATURE WILL RANGE FROM 1 TO 2 INCHES ACROSS SWRN MN...TO UP TO ONE HALF INCH NORTHEAST OF A LINE FROM ALEXANDRIA... HUTCHINSON...AND MANKATO. AS THIS IS BEING WRITTEN...THE 18Z GFS CAME IN WITH MUCH HIGHER QPF AND 0.15 INCHES NOW EXTENDS NORTH TO AXN/STC/RNH. WHILE THIS RUN IS AN OUTLIER...TRENDS WILL NEED TO BE MONITORED FOR LATER FORECASTS. THAT SHORT WAVE WILL DISSIPATE FRIDAY EVENING WITH DRY CONDITIONS EXPECTED LATE FRIDAY NIGHT AS HIGH RH IS LOST IN THE DGZ LAYER AND ABOVE. LONG TERM...SATURDAY THROUGH THURSDAY. THE BETTER SYSTEM OF THE TWO STILL LOOKS LIKE IT WILL IMPACT THE AREA SATURDAY AFTERNOON THROUGH SUNDAY...BUT PRECISE DETAILS ARE FAR FROM CERTAIN. MODELS HAVE...HOWEVER...COME INTO BETTER AGREEMENT WITH THE OVERALL EVOLUTION OF THIS STORM FROM PREVIOUS RUNS. AS A 160 KT UPPER JET DIVES DOWN THE WESTERN ROCKIES...A MID LEVEL DISTURBANCE WILL EJECT EASTWARD ACROSS CENTRAL MINNESOTA SATURDAY EVENING. IT WILL REMAIN LARGELY DETACHED FROM ANOTHER DISTURBANCE HANGING BACK IN THE DEEP TROUGH OVER THE FOUR CORNERS ON SUNDAY AFTERNOON...SO AN IMPRESSIVE WINTER STORM IS NOT ANTICIPATED BUT ACCUMULATING SNOW IS STILL FORECAST...ESPECIALLY OVER ERN/CNTRL MN AND WRN WI. DECENT ISENTROPIC LIFT IS STILL BEING SEEN ON THE 285 AND 290K SURFACES EARLY SATURDAY AFTERNOON OVER WRN MN WHICH WILL SPREAD EASTWARD SATURDAY NIGHT. THIS LIFT SHOULD PRODUCE A BAND OF SNOW THAT WILL PROPAGATE ACROSS THE AREA FROM WEST TO EAST SATURDAY AFTERNOON INTO SUNDAY. BETTER LIFT AND HIGHER MOISTURE CONTENT WITH THIS SYSTEM SHOULD OVERCOME DRY AIR IN THE BOUNDARY LAYER FAIRLY QUICKLY...WITH MODERATE TO HEAVY SNOWFALL RATES POSSIBLE SIMILAR TO THE THANKSGIVING SYSTEM. INTENSITY WILL MAKE UP FOR THE DURATION WHICH IS ONLY EXPECTED TO BE ABOUT 6-12 HOURS...EXCEPT OVER WRN WI WHERE IT MAY LINGER A BIT LONGER. MID LEVEL DRY SLOT PUNCHING IN FROM THE SOUTHWEST BEHIND THE LOW WILL CLEAR OUT ANY STEADY SNOW LATE SATURDAY NIGHT AND SUNDAY MORNING ACROSS CENTRAL AND WESTERN MN. THE DRY SLOT SHOULD REACH WRN WI BY SUNDAY AFTERNOON. WRAP AROUND SNOW SHOWERS COULD DROP DOWN ALONG THE ARCTIC COLD FRONT SUNDAY AFTERNOON. TAKING AN AVERAGE OF QPF FROM THE MODELS BRINGS BETWEEN A TENTH AND A THIRD OF AN INCH...MOST BEING ACROSS WRN WI AND LEAST ACROSS SWRN MN. USING ROUGHLY A 13:1 RATIO /POSSIBLY LOWER IF THE NAM BL TEMPS IN THE MID/UPPER 30S VERIFY/ WOULD BRING AN INCH ACROSS SWRN MN...ABOUT 2 INCHES IN THE TC METRO...AND 3 TO 4 INCHES OVER WRN WI. USING THE GARCIA METHOD OF DOUBLING THE AVERAGE MIXING RATIO OVER A 12 HR PERIOD WOULD RESULT IN 4-5 INCHES OF SNOW...BUT CUTTING THAT IN HALF FOR A 6-HR DURATION BRINGS ABOUT 2 INCHES WHICH MATCHES THE CURRENT THINKING. BEHIND THE ARCTIC FRONT...THE FIRST REAL TASTE OF WINTER WILL ARRIVE ON SUSTAINED 20 KT WINDS...WITH SOME GUSTS TO 30 KTS OVER WRN MN SUNDAY AFTERNOON. DEPENDING ON THE QUALITY OF THE SNOW...COULD SEE SOME BLOWING AND DRIFTING SUNDAY AFTERNOON. TEMPERATURES WILL PLUMMET FROM THE 20S AND 30S TO THE SINGLE DIGITS NORTHWEST AND LOWER 20S IN WRN WI BY EARLY EVENING WITH WIND CHILL READINGS AS LOW AS 15 BELOW NEAR THE SD BORDER. WHILE WINDS WILL SUBSIDE A BIT SUNDAY NIGHT...HIGH PRESSURE BUILDING IN AND TEMPERATURES FALLING INTO THE -3 TO +11 RANGE WILL BRING SUBZERO WC READINGS EVERYWHERE...BUT COULD APPROACH WIND CHILL ADVY CRITERIA /-20 TO -25F/ OVER WRN AND CNTRL MN IF WIND SPEEDS REMAIN ABOVE 10 KTS. AFTER A COLD DAY MONDAY...A MILDER AIRMASS WILL RETURN FOR MIDWEEK AS A SERIES OF WEATHER SYSTEMS TRAVERSE THE FAR NORTHERN CONUS. AT THIS POINT...THE BEST CHANCES FOR ACCUMULATING SNOW WILL REMAIN NORTH OF THE CWA. && .AVIATION.../06Z TAF ISSUANCE/ MAIN CHANGE WITH 06Z TAFS...IS THAT 00Z NAM/GFS ALONG WITH LAST FEW RUNS OF THE HRRR IS STARTING TO INCREASE CONFIDENCE IN -SN OCCURRING AT ALL TERMINALS. TIMING IN TAFS STILL LOOKS GOOD AS WELL. GFS/NAM ALONG WITH THE HRRR SEEM TO BE HONING IN ON A BAND OF -SN COMING OUT OF CENTRAL SODAK...THEN DUE EAST ACROSS THE MPX AREA FRI AFTERNOON/EVENING. AXN/STC MAY BE JUST NORTH OF THE HEAVIEST SNOW...BUT A QUICK 1-3 INCHES IS LOOKING MORE PLAUSIBLE FOR RWF AND MSP. FOR WI...MODELS CONTINUE TO SHOW FORCING AND SNOW WANING AS THINGS GET INTO WI...SO LEFT VIS RESTRICTIONS ANT RNH/EAU AT MVFR. CIGS WILL BE SLOW TO DESCEND...BUT BY FRIDAY NIGHT...925-850 RH FROM THE GFS/NAM ALONG WITH SREF PROBS FOR CIGS LESS THAN 3K FT WOULD INDICATE THAT A BAND OF IFR/MVFR MAY GET HUNG UP ACROSS MN...SO DID TREND CIGS DOWNWARD...ESPECIALLY FOR AXN/RWF. KMSP...290/295K ISENTROPIC SFCS ALONG WITH MID-LEVEL FGEN WOULD SAY SNOW COULD START AS EARLY AS 18Z AT MSP...BUT BEST FORCING STILL WAITS UNTIL 00Z TO BRING IN BEST FORCING...SO BROUGHT IN IFR VSBYS THEN. LOOKS LIKE THE EVENING RUSH COULD SEE 1-3 INCHES OF SNOW IF CURRENT GFS/NAM PANS OUT. FOR WINDS...THEY WILL BE LIGHT WITH HIGH PRESSURE SLIDING BY THROUGH THE PERIOD WITH JUST A GRADUAL VEERING OF WINDS FROM NW TO SE THROUGH THE PERIOD. DIRECTIONS LOOK TO CROSS AN 040 DIRECTION AROUND 3Z. /OUTLOOK FOR KMSP/ SAT...MVFR CIGS ENDING MID MORNING...THEN VFR. MVFR/IFR CIGS/VIS DEVELOPING OVERNIGHT WITH SN. WINDS SE AT 10KTS. SUN...SN ENDING IN MORNING...1-3 IN POSSIBLE. MVFR/IFR CIGS/VIS IN MORNING. MVFR CIGS AFTERNOON. WINDS BCMG NW 20G30KTS. MON...MVFR CIGS EARLY...BECOMING VFR IN AFTERNOON. WINDS NW 15KTS IN MORNING...BCMG SW AT 5 KTS IN AFTERNOON. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...NONE. WI...NONE. && $$ BORGHOFF/MPG
AREA FORECAST DISCUSSION...UPDATED
NWS ST LOUIS MO
850 PM CST SAT DEC 8 2012 .UPDATE... ISSUED AT 849 PM CST SAT DEC 8 2012 MUCH OF THE CWA HAS BEEN DRY SO FAR THIS EVENING WITH LOW CLOUDS AND SOME PATCHY FOG. STILL BELIEVE THAT RAIN CHANCES WILL INCREASE SIGNIFICANTLY LATER THIS EVENING AND OVER NIGHT AS LARGE SCALE ASCENT INCREASES AHEAD OF SHORTWAVE MOVING ACROSS THE CENTRAL PLAINS. RAP HAS BEEN CONSISTENT IN SHOWING AN INCREASE IN LOW LEVEL MOISTURE CONVERGENCE ALONG 850MB WARM FRONT TONIGHT. ONLY CHANGE IN FORECAST IS TO REFLECT NEAR TERM PRECIPITATION AND TEMPERATURE TRENDS. BRITT && .SHORT TERM... ISSUED AT 213 PM CST SAT DEC 8 2012 (TONIGHT) SHORTWAVE DIVING THROUGH EASTERN MONTANA AT THIS TIME IS FORCING CYCLOGENESIS OVER THE NORTHERN PLAINS. SOUTHWESTERLY LOW LEVEL FLOW WILL BEGIN TO INCREASE OVER THE LOWER MISSISSIPPI VALLEY TONIGHT IN RESPONSE TO THE STRENGTHENING LOW. THIS WILL BRING THE QUASI-STATIONARY FRONT HANGING OVER ARKANSAS BACK NORTH INTO OUR AREA BY EARLY SUNDAY MORNING. LOW LEVEL JET RAMPS UP AROUND 30KTS THIS EVENING PRODUCING DECENT 850MB MOISTURE CONVERGENCE OVER THE AREA. AT FIRST IT`S RATHER WEAK AND DIFFUSE...BUT BECOMES STRONGER OVER NORTHEAST MISSOURI AND WEST CENTRAL ILLINOIS LATE TONIGHT AS THE 850MB TEMP GRADIENT TIGHTENS UP. EXPECT WIDELY SCATTERED SHOWERS TO DEVELOP THIS EVENING OVER SOUTHEAST MISSOURI...OVERSPREADING THE ENTIRE AREA AND INCREASING IN AREAL COVERAGE IN RESPONSE TO THE INCREASING MOISTURE CONVERGENCE. COULD SEE A LITTLE THUNDER AS WELL...PRIMARILY OVER SOUTHEAST MISSOURI AND SOUTHERN ILLINOIS WHERE MUCAPE IS FORECAST TO EXCEED 250 J/KG. TEMPERATURES WILL TAKE AN INITIAL DIP THIS EVENING...BUT SHOULD LEVEL OUT AND POSSIBLY RISE SLIGHTLY AS THE WARM FRONT MOVES UP INTO THE BI-STATE REGION LATE TONIGHT. CARNEY && .LONG TERM... ISSUED AT 213 PM CST SAT DEC 8 2012 SUNDAY AND SUNDAY NIGHT... THE WARM FRONTAL BOUNDARY WILL BE LOCATED ACROSS THE SOUTHERN PORTION OF THE CWA BY 12Z...WITH THE OVERNIGHT WARM ADVECTION PRECIPITATION BEGINNING TO LIFT NORTH AND EAST OF THE CWA. THINK THERE WILL BE A LULL IN THE RAIN BY MIDMORNING ACROSS A GOOD AMOUNT OF THE CWA UNTIL A STRONG COLD FRONT MOVES SOUTHEAST ACROSS THE AREA IN THE AFTERNOON AND EVENING. THIS FRONT WILL REINFORCE THE BAROCLINICITY TO OUR SOUTHEAST AND LEAD TO LIGHT RAIN REDEVELOPING ACROSS AT LEAST THE SOUTHEAST HALF OF THE CWA FOR THE AFTERNOON AND EARLY EVENING HOURS. LUCKILY...ALL INDICATIONS ARE THAT THE RAIN WILL TURN TO COLD SUNDAY NIGHT AS DEEP MOISTURE IS SHUNTED TO THE SOUTHEAST AS THE WINTER BLAST ARRIVES AND COLD AIR DEEPENS ACROSS THE CWA. MONDAY THROUGH THURSDAY... A RAW WINTER DAY IS ON TAP FOR MONDAY AS TEMPERATURES STRUGGLE TO RISE BACK ABOVE FREEZING WITH STRONG COLD ADVECTION AND A GUSTY NORTHWEST WIND. THE WINTER CHILL SHOULD BE BRIEF THOUGH...AS TEMPERATURES WILL ALREADY BEGIN MODERATING BY MIDWEEK DESPITE A TROF MOVING ACROSS THE MIDWEST. TEMPERATURES WILL RISE BACK ABOVE NORMAL FOR THE END OF THE WEEK AS THE UPPER FLOW BECOMES SOUTHWEST IN RESPONSE TO A STRONG STORM SYSTEM DIGGING SOUTH ALONG THE WEST COAST. FRIDAY THROUGH SATURDAY... NEARLY ALL OF THE MEDIUM RANGE GUIDANCE DEPICTS A STRONG SHORTWAVE AND SURFACE LOW PASSING TO THE WEST OF THE CWA FRIDAY NIGHT. THIS PATTERN IS INDICATIVE OF ABOVE NORMAL TEMPERATURES AND A GOOD CHANCE OF SHOWERS AND THUNDERSTORMS. CVKING && .AVIATION... ISSUED AT 541 PM CST SAT DEC 8 2012 STRATUS CLOUDS AROUND 1500 FT WILL GRADUALLY LOWER TGT ALONG WITH THE DEVELOPMENT OF FOG. LIGHT RAIN WILL ALSO MOVE BACK INTO THE AREA LATE TGT AS THE STATIONARY FRONT ACROSS NRN AR LIFTS BACK NWD INTO SRN MO AND A SWLY LOW LEVEL JET BRINGS INCREASING AND DEEPENING LOW LEVEL MOISTURE INTO THE AREA. CEILINGS WILL LIKELY LOWER TO AROUND 500 FT WITH VSBYS OF 1-3SM IN LIGHT RAIN AND FOG. THE E-NELY SFC WIND WILL GRADUALLY VEER AROUND TO AN E-SELY DIRECTION. THE RAIN SHOULD END IN UIN AND COU BY LATE SUN MRNG AS A SFC WAVE ALONG THE FRONT MOVES E OF THE AREA...WHILE A STRONG COLD FRONT DROPS SEWD INTO THE REGION. RAIN WILL LIKELY CONTINUE IN THE ST LOUIS METRO AREA SUN AFTN UNTIL THE COLD FRONT MOVES SE OF THE AREA WITH CAA AND DRYING OF THE LOW LEVELS BEHIND THE COLD FRONT. THE SFC WIND WILL VEER AROUND TO A NWLY DIRECTION AS THE SFC WAVE SHIFTS E OF THE AREA...AND THEN STRENGTHENS AFTER PASSAGE OF THE STRONG COLD FRONT SUN AFTN. WILL SEE AN IMPROVEMENT IN VSBYS LATE SUN MRNG AND AFTN...BUT ONLY A VERY GRADUAL RISE IN CEILING HEIGHTS WITH CIGS RISING TO AROUND 1000 FT BY EARLY AFTN. SPECIFICS FOR KSTL...CIG HEIGHTS SHOULD LOWER LATER THIS EVNG WITH FOG DEVELOPING. THE CIGS SHOULD LOWER TO AROUND 500 FT LATE TGT WITH VSBYS FALLING TO AROUND 2SM AS LIGHT RAIN MOVES INTO THE AREA. THE NELY SFC WIND WILL GRADUALLY VEER AROUND TO AN ELY DIRECTION LATER THIS EVNG...AND A SELY DIRECTION LATE TGT AS A SFC RIDGE SHIFTS WELL NE OF OUR AREA WHILE A WARM FRONT APPROACHES STL FROM THE S. THE RAIN SHOULD END BY SUN EVNG AS A SFC WAVE ALONG THIS FRONT SHIFTS WELL NE OF STL AND A STRONG COLD FRONT MOVES SE OF STL CAUSING THE SFC WIND TO VEER AROUND TO A W-NWLY DIRECTION AND STRENGTHEN DURING THE AFTN AND EVNG HOURS. THE VSBYS WILL IMPROVE DURING THE LATE MRNG AND AFTN HOURS WITH THE CLOUD CEILING RISING TO AROUND 1000 FT BY AFTN AND 1500 FT BY SUN EVNG. GKS && .LSX WATCHES/WARNINGS/ADVISORIES... MO...NONE. IL...NONE. && $$ WFO LSX
AREA FORECAST DISCUSSION
NWS KANSAS CITY/PLEASANT HILL MO
1141 PM CST THU DEC 6 2012 ...UPDATED AVIATION DISCUSSION... .DISCUSSION... Now appears after the fact that the 18z model runs were out to lunch as far as the rain is concerned for tonight. 00z TOP raob was pretty dry below 700mb except for the small layer of moisture around 850mb. 00z NAM and RAP are much much drier and barely eke out any qpf overnight. Best chance for light rain this evening will be across far northern MO and even then that area doesn`t look to promising. After midnight some light rain or sprinkles may try to form over parts of west central and central MO as the moisture thickens around 850mb. Latest satellite data shows a weak mid level shortwave now in far eastern KS and as it passes by it strips away the deeper moisture and thus ends the threat of rain. Appears the upper jet dynamics associated with the southern stream don`t trump the lack of decent moisture. Bottom-line is need to lower pops and even where slight chance pops remain it may be more of a case of a few sprinkles. Otherwise, no major changes made to any of the other elements. MJ && .PREV DISCUSSION... Short Term (Tonight and Friday)... In the near term, the primary forecast concern will be precipitation chances for tonight through midday Friday. Pacific midlevel moisture streaming through the Plains states has combined with a small amount of energy ejecting out of the semi-permanent lee-side trough feature over the southern High Plains to create light showers across portions of eastern Nebraska, eastern Kansas, western Missouri, and Iowa this afternoon. However, dry near-surface conditions has led to a large amount of evaporation below cloud base, keeping the amount of rain that reaches the surface nominal. Forcing for precipitation from the southern shortwave trough looks strongest across the majority of the forecast area in the 03z-09z time frame, while relative low-level moisture also increases, slightly increasing the chance for any measurable precipitation. The overall chance of showers remains low through the period, but occurs over an extended period of time from this afternoon through Friday afternoon as the southern jet slowly drops southeast. Rain chances associated with this system should end altogether sometime late Friday afternoon or evening. Fairly extensive cloud cover should keep high temperatures muted throughout the period (albeit above normal), and low temperatures mild. The only exception will be over the northwest on Friday night, as clouds gradually clear and temperatures begin to drop. Laflin Long Term (Saturday-Thursday)... Consistency among forecast model guidance has increased over the last couple of runs with forecast confidence also increasing with regards to weekend precipitation chances. Forecast confidence remains high for significant cooler weather Sunday into early next week before temperatures begin to moderate the middle of next week. Strong shortwave energy moving through the Pacific Northwest into the Central Rockies will deepen a broad upper trough in the Plains and the Ohio Valley. In response to height falls aloft, surface low pressure is progged to develop across the Northern Plains and track through the upper Midwest with the potential of another surface low to move through the Southern Plains into the Lower and Middle Mississippi Valley. An associated strong cold front will move through the Plains entering Northwest Missouri early Sunday morning. Strong cold air advection behind the front will likely produce falling temperatures Sunday afternoon. Precipitation amounts are expected to remain light. Initially precipitation will be driven by warm air advection and moisture transport processes ahead of the frontogenetic forcing. Due to the progressive movement of the upper trough...only shallow moisture return is anticipated in Northeast Kansas and Northwest Missouri with deeper moisture return occurring across the Lower and Middle Mississippi River Valley. Thus have continued with precipitation amounts generally less than a quarter of an inch. While light snow will be possible post frontal passage, drier air will rapidly advect into the dendritic zone. This drier air intrusion along with low snowfall rates and warm ground temperatures from the recent above normal temperatures will limit any accumulation to around a half inch or less where snow occurs. Below normal temperatures are likely Monday and Tuesday before temperatures begin to rebound with high pressure building east and southerly return flow developing with a lee side trough in the High Plains. Angle && .AVIATION... For the 06z TAFs, rain chances have decreased considerably for the overnight hours as a shortwave trough moves east across the MO/KS state line. Earlier models were overly generous on saturating a deep layer of the atmosphere. 00z TOP raob was dry below 700mb and latest model runs/radar trends now confirm a basically dry forecast. Main concern is how long will MVFR cigs last. NEF analysis shows MVFR cigs forming over south central IA and trajectories will likely advect this moisture into the terminals overnight. This supports the 00z Bufr soundings so will maintain MVFR cigs until at least mid morning Friday. Should see drier air gradually work in from the north and allow cigs to rise to low end VFR by late morning or early afternoon...eventually scattering out by late in the day. MJ && .EAX WATCHES/WARNINGS/ADVISORIES... MO...NONE. KS...NONE. && $$ WFO EAX
AREA FORECAST DISCUSSION
NWS NORTH PLATTE NE
606 PM CST SAT DEC 8 2012 .AVIATION...FOR THE KLBF AND KVTN TERMINALS THROUGH 00Z MONDAY. AN UPPER LEVEL TROUGH OF LOW PRESSURE WILL TRACK ACROSS THE CENTRAL AND NORTHERN PLAINS OVER THE NEXT 24 HOURS...LEADING TO ABUNDANT CLOUDINESS AND WINDY CONDITIONS ACROSS WESTERN AND NORTH CENTRAL NEBRASKA. AT THE KLBF TERMINAL...EXPECT CIGS AON 10000 FT AGL THROUGH 10Z TONIGHT...DROPPING DOWN TO AROUND 4000 FT AGL. CIGS WILL BEGIN TO SCATTER OUT AFTER 17Z SATURDAY. AT THE KVTN TERMINAL...CIGS WILL DROP FROM 5000 FT AGL DOWN TO 1500 FT AGL OVERNIGHT AND REMAIN THERE THROUGH MIDDAY SUNDAY. SKIES WILL BEGIN TO SCATTER OUT BY LATE AFTERNOON. FOR BOTH TERMINALS...LOOK FOR NORTHERLY WINDS TO INCREASE TO 15 TO 25 KTS TONIGHT WITH PERIODIC GUSTS TO AROUND 30 KTS AT BOTH TERMINALS. WINDS WILL GRADUALLY DIMINISH LATE SUNDAY AFTERNOON. && .PREV DISCUSSION... /ISSUED 244 PM CST SAT DEC 8 2012/ ...MUCH COLDER WITH WINDY CONDITIONS LATE TONIGHT AND SUNDAY... SYNOPSIS... SURFACE LOW PRESSURE RESIDES ACROSS THE CENTRAL HIGH PLAINS WITH MAIN LOW FORMING NEAR PINE RIDGE SOUTH DAKOTA. LEADING EDGE OF COLD FRONT JUST PASSED CHADRON. STEEP LAPSE RATES ATTRIBUTING TO CONVECTIVE SNOW SHOWERS PANHANDLE INTO NORTH CENTRAL. MUCH OF RADAR ECHOES NOT REACHING GROUND EFFECTIVELY DUE TO FAIRLY LARGE TEMPERATURES AND DEWPOINT SPREAD. NEVERTHELESS... THIS HAS BEEN MOISTENING UP THE ATMOSPHERE FOR UPSTREAM DEVELOPMENT TO TAKE ADVANTAGE OF FOR LATE AFTERNOON INTO THIS EVENING. DISCUSSION... SHORT TERM...TONIGHT THROUGH TUESDAY. MAIN FORECAST CONCERNS OVER THE NEXT 36 HOURS INVOLVES THE THREAT OF LIGHT SNOW...A RETURN OF COLD TEMPERATURES...AND THE POTENTIAL OF ADVISORY CRITERIA WIND SPEEDS. MODELS CONTINUE TO SHOW GOOD AGREEMENT IN THE NEAR TERM IN WHICH THE SHORTWAVE TROUGH CURRENTLY LOCATED FROM CENTRAL SOUTH DAKOTA INTO EASTERN MONTANA AND ASSOCIATED SURFACE LOW DEEPEN AND EJECT EAST ACROSS THE NORTHERN PLAINS...DRAGGING A STRONG COLD FRONT THROUGH THE CWA OVERNIGHT TONIGHT. THE RAP MODEL CONTINUES TO INDICATE THE SURFACE LOW NEAR AND SOUTH OF I90 TONIGHT WHICH REMAINS FARTHER SOUTH THAN OTHER SHORT TERM MODELS. AN H3 JET MAX ACROSS NORTHERN COLORADO AND SOUTHERN NEBRASKA THIS EVENING WILL BE FAVORABLE FOR ASCENT IN THE LEFT EXIT REGION OF JET ACROSS NORTH CENTRAL NEBRASKA. AS SUGGESTED BY THE RAP MODEL...REGIONAL GEM AND TO A LESSER EXTEND THE NAM...BANDED SNOWFALL IS FAVORABLE FROM NEAR MULLEN THROUGH BASSETT. LOCAL SNOWFALL AMOUNTS NEAR AN INCH POSSIBLE IN THESE BANDED AREAS. OTHERWISE...LIGHT SNOW ALSO FORECAST TO DEVELOP AND DROP SOUTH INTO FAR NORTHERN NEBRASKA LATE TONIGHT INTO SUNDAY MORNING. THIS IS WITHIN SOUTHERN PERIPHERY OF DEFORMATION ZONE TO BE ACROSS EASTERN SOUTH DAKOTA INTO SOUTH CENTRAL SOUTH DAKOTA. ANY ASSOCIATED SNOWFALL WOULD REMAIN A HALF INCH OR LESS. ACROSS THE SOUTHERN HALF OF FORECAST AREA...ANY LINGERING SNOW OR FLURRIES FROM THIS EVENING SHOULD END SOON AFTER MIDNIGHT. STRONG COLD AIR ADVECTION AND LOW LEVEL PRESSURE RISES WILL FOLLOW THE SURFACE BOUNDARY PASSAGE OVERNIGHT TONIGHT. THE PRESSURE RISES WILL HELP TIGHTEN THE SURFACE GRADIENT AND ALLOW FOR GUSTY CONDITIONS LATER TONIGHT INTO SUNDAY. THE MODELS HAVE SHOWN A SLIGHT SOUTHWARD TREND IN THE TRACK OF THE SURFACE LOW...NOW ACROSS FAR SOUTHWEST MINNESOTA. THIS TRACK FAVORS SLIGHTLY STRONGER SURFACE WINDS THAN PREVIOUSLY ANTICIPATED. WILL KEEP WIND SPEEDS JUST BELOW ADVISORY CRITERIA...ESPECIALLY SINCE THE STRONGEST PRESSURE RISES ARE EXPECTED DURING THE EARLY MORNING HOURS...DIURNALLY UNFAVORABLE FOR ADVISORY CRITERIA WIND. BUT...WIDESPREAD SUB ZERO WIND CHILLS WILL OCCUR...WITH THE POTENTIAL OF SOME OF THE LOWEST READINGS APPROACHING MINUS TEN OR COLDER THROUGH SUNDAY MORNING ACROSS OUR NORTHERN ZONES. HIGHS ON SUNDAY WILL BE COLD...WITH READINGS TRENDED DOWN TO NEAR 15 AT VALENTINE TO THE MID 20S FAR SOUTH. WE WILL NEED TO WATCH LOW TEMPERATURES FOR MONDAY MORNING...AS ANY SNOWFALL WOULD ALLOW READINGS TO PLUMMET...TO POSSIBLY BELOW ZERO. CURRENT FORECAST HAS LOWS 1 TO 5 ABOVE MOST AREAS...AS WIDESPREAD ACCUMULATING SNOW IS NOT ANTICIPATED. TEMPERATURES BEGIN TO MODERATE SLOWLY MONDAY AFTERNOON AS WEAK WAA INFILTRATES FROM THE WEST IN ADVANCE OF THE NEXT SHORTWAVE TROUGH. HIGHS TO RANGE IN THE 30S. THEN A WESTERLY DOWNSLOPE TUESDAY TO WARM READINGS TO THE MID 30S TO LOWER 40S. LONG TERM...TUESDAY NIGHT THROUGH SATURDAY. SHORTWAVE RIDGING AND WAA TAKE HOLD WEDNESDAY THROUGH THURSDAY...WITH TEMPERATURES SLIGHTLY ABOVE SEASONAL NORMS WEDNESDAY AND NEAR NORMAL THURSDAY. WILL NEED TO MONITOR IF A BACK DOOR COLD FRONT DROPS INTO NORTH CENTRAL NEBRASKA THURSDAY. THE ECMWF AND GEM KEEP COLDER AIR TO THE NORTH INTO SOUTH DAKOTA...WHILE THE GFS BRINGS IT SOUTH INTO NORTHERN NEBRASKA. THE NEXT SIGNIFICANT TROUGH IS SHOWN TO REACH THE FOUR CORNERS REGION 12Z FRIDAY AND TRACK INTO NORTHWEST MISSOURI AS A NEGATIVELY TILTED CLOSED LOW BY 12Z SATURDAY PER THE ECMWF SOLUTION. THE GFS ALSO INDICATES A NEGATIVELY TILTED TROUGH...ALTHOUGH AS AN OPEN WAVE FROM WESTERN SOUTH DAKOTA INTO NORTHERN NEBRASKA. PRECIPITATION CHANCES NOW BROUGHT INTO EASTERN NEBRASKA FRIDAY NIGHT INCLUDING FAR EASTERN PORTIONS OF NORTH CENTRAL NEBRASKA. HIGHS FRIDAY FORECAST TO RANGE IN THE 30S AND MID 30S TO LOW 40S SATURDAY. && .LBF WATCHES/WARNINGS/ADVISORIES...NONE. && $$ SHORT TERM/EXTENDED...ROBERG AVIATION...BUTTLER
AREA FORECAST DISCUSSION...UPDATED
NWS NORTH PLATTE NE
524 AM CST FRI DEC 7 2012 .UPDATE... .AVIATION... VFR IS EXPECTED MOST AREAS TODAY AND TONIGHT. THE GENERAL MODEL CONSENSUS SUGGESTS MVFR CIGS WILL DEVELOP THIS AFTERNOON ACROSS NORTHERN NEB...GENERALLY ALONG AND NORTH OF HIGHWAY 20. THIS RESTRICTION IS ASSOCIATED WITH A COLD FRONT FORECAST TO DROP THROUGH THE FCST AREA. THE RAP MODEL AND OTHERS SUGGEST THE MVFR CIGS WILL SPREAD EAST AND SOUTH THIS AFTN AND THIS EVENING. THE PROBLEM IN THE MODELS REVOLVES AROUND THE DURATION OF THE MVFR. SO AS A GENERAL GUIDELINE...CEILINGS ARE EXPECTED TO IMPROVE TO VFR ALL AREAS TONIGHT...BETWEEN 01Z-06Z. && .PREV DISCUSSION... /ISSUED 245 AM CST FRI DEC 7 2012/ SYNOPSIS... AT 08Z...SURFACE ANALYSIS SHOWED LOW PRESSURE CENTERED OVER SOUTHEAST WYOMING WITH A STATIONARY FRONT EXTENDING INTO EASTERN COLORADO. AN INVERTED TROUGH EXTENDED FROM THE LOW CENTER TO NORTHEAST SOUTH DAKOTA. IN THE UPPER LEVELS...WATER VAPOR IMAGERY INDICATED A BROAD STREAM OF MID-LEVEL MOISTURE COMING ACROSS THE ROCKIES FROM THE PACIFIC NORTHWEST. IN THE WEST...AN UPPER TROUGH WAS DIGGING ALONG THE CALIFORNIA COAST. RADAR SHOWED SOME ECHOES MOVING ACROSS NORTHERN NEBRASKA JUST SOUTH AND EAST OF THE INVERTED TROUGH. DISCUSSION... AS AN OVERVIEW...THE STATIONARY FRONT ALONG THE EASTERN SLOPES OF THE ROCKIES WILL BE THE PLAYER IN THE FORECAST THROUGH SUNDAY AS IT OSCILLATES ACROSS THE HIGH PLAINS. WITH EACH OSCILLATION...THE DYNAMICS IN THE AREA BECOME SUFFICIENT FOR PRODUCING SIGNIFICANT LIFT. SHORT RANGE...TODAY AND TONIGHT. AS THE FRONT ALONG THE EASTERN SLOPE MAKES ITS WAY NORTHEASTWARD ACROSS NEBRASKA...SIGNIFICANT ISENTROPIC UPGLIDE DEVELOPS EARLY THIS MORNING AS INDICATED BY MOISTURE TRANSPORT VECTORS ON THE 290K AND 295K SURFACES. THE SOURCE OF THE MOISTURE TRANSPORT IS THE NORTHWEST U.S. AND THE EXTREME SOUTHWEST. AS A RESULT...THE WESTERN MOST AIR WILL BE DRY WITH SATURATION DEFICITS OF 50-120MB IN THE 290-300K LAYER. IT SATURATES NEAR A MERRIMAN-THEDFORD-LEXINGTON LINE. IN FACT...CURRENT RADAR ECHOES IN NORTHERN NEBRASKA INDICATE THAT SATURATION HAS BEEN REACHED IN THE LIFTED LAYER. AT THIS TIME...IT APPEARS THAT SOME CHANCE OF LIGHT SNOW IS APPROPRIATE THIS MORNING. ACCUMULATIONS WILL BE LIMITED BECAUSE THE COVERAGE IS NOT HIGH. NORTHEAST-SOUTHWEST CROSS SECTIONS INDICATE A TEMPERATURE PROFILE FAVORABLE FOR SNOW THIS MORNING. HOWEVER...THE SAME CROSS SECTIONS INDICATE A SHALLOW VERY DRY LAYER NEAR THE SURFACE...SO THE NEAR SURFACE LAYER WILL NEED TO MOISTEN BEFORE PRECIPITATION CAN REACH THE SURFACE. WITH THE MIXING RATIO OF 2-3G/KG...NOT A LOT OF MOISTURE IS AVAILABLE AND THE SYSTEM IS LIKELY TO BE OUT OF CENTRAL AND SOUTHWEST NEBRASKA BEFORE THAT SATURATION CAN OCCUR. THEREFORE...THE CHANCES OF PRECIPITATION TODAY WILL BE VERY LOW IF NOT COMPLETELY NON-EXISTENT FOR CENTRAL AND SOUTHWEST NEBRASKA. BEHIND THE WARM FRONT...A COLD FRONT PLUNGES THROUGH NORTH CENTRAL THROUGH SOUTHWEST NEBRASKA BY EARLY THIS AFTERNOON. ALTHOUGH SYSTEM RELATIVE ISENTROPIC LIFT IS SIGNIFICANT AND ENHANCED WITH FRONTOGENETIC FORCING...THE AIR BEING LIFTED IS DRY AND PRECIPITATION IS UNLIKELY. MEDIUM RANGE...SATURDAY THROUGH SUNDAY NIGHT. WE ARE STILL GETTING SOME MIXED SIGNALS REGARDING THE SYSTEM SATURDAY AND SUNDAY FROM THE MEDIUM RANGE MODEL OUTPUT. FOR A BRIEF PERIOD SATURDAY MORNING...THE FRONT RETURNS TO SOUTH CENTRAL AND SOUTHWEST NEBRASKA AND SOME ISENTROPIC UPGLIDE IS INDICATED ONCE AGAIN UNTIL THE COLD FRONT PLUNGES THROUGH. THE COLD FRONT IS VERY STRONG AND SYSTEM-RELATIVE ISENTROPIC LIFT WILL ALSO BE STRONG WITH FRONTOGENETIC ENHANCEMENT LIKELY. THE NORTH-SOUTH CROSS SECTION THROUGH OGALLALA INDICATES AN UNSTABLE LAYER 288-297K AND THE SATURATED AIR IS LIFTED INTO THE DENDRITIC LAYER 291-294K. THEREFORE...THERE WILL BE NO DIFFICULTY FOR SNOW CRYSTAL FORMATION. HOWEVER...ONCE AGAIN...THE LOWEST LAYERS ARE VERY DRY. STILL... LATENT HEAT ABSORPTION COULD COOL THE LOWEST LAYERS TO NEAR SATURATION AND ALLOW SNOW TO REACH THE SURFACE. THE BOTTOM LINE IS THAT WE DO NOT HAVE HIGH CONFIDENCE IN THE OCCURRENCE OF PRECIPITATION AND...IF IT DOES OCCUR...AMOUNTS WILL BE LOW. WITH THE PASSAGE OF THE FRONT...WINDY CONDITIONS ARE EXPECTED. A STRONG PRESSURE GRADIENT IS INDICATED AND STRONG COLD ADVECTION WILL KEEP THE SURFACE TO 2KM LAYER WELL MIXED. EXTENDED...SUNDAY NIGHT THROUGH THURSDAY. AFTER THE FRONT PUSHES THROUGH...NORTH-NORTHWEST FLOW ALOFT WILL STEER COLD AIR MASSES ONTO THE HIGH WITH A TRAJECTORY FROM NORTHERN BRITISH COLUMBIA AND THE SOUTHERN YUKON SUNDAY NIGHT THROUGH TUESDAY. IF ANY SNOW OCCURS SATURDAY AND SUNDAY...TEMPERATURES MONDAY MORNING AND TUESDAY MORNING COULD BE THE COLDEST OF THE SEASON. AT THIS TIME...WE ARE NOT GOING TO SINGLE DIGITS BECAUSE OF THE LACK OF CONFIDENCE THAT SNOW WILL OCCUR. SOME WARMING CAN BE EXPECTED WEDNESDAY AND THURSDAY THOUGH NOT ANYWHERE NEAR THE HIGH TEMPERATURES THAT WERE OBSERVED LAST WEEK. AVIATION... VFR IS EXPECTED MOST AREAS TODAY AND TONIGHT. THE GENERAL MODEL CONSENSUS SUGGESTS MVFR CIGS WILL DEVELOP THIS AFTERNOON ALONG AND NORTH OF HIGHWAY 20. THIS RESTRICTION IS ASSOCIATED WITH A COLD FRONT FORECAST TO DROP THROUGH THE FCST AREA. CEILINGS ARE EXPECTED TO IMPROVE TO VFR ALL AREAS TONIGHT...BETWEEN 01Z-06Z. && .LBF WATCHES/WARNINGS/ADVISORIES...NONE. && $$ SHORT TERM/EXTENDED...CDC AVIATION...CDC
AREA FORECAST DISCUSSION
NWS BINGHAMTON NY
1247 PM EST FRI DEC 7 2012 .SYNOPSIS... A WARM FRONT WILL BRING RAIN TO MUCH OF THE REGION TODAY. THIS WILL MARK THE BEGINNING OF A RATHER UNSETTLED PERIOD WITH SCATTERED SHOWERS POSSIBLE EACH DAY AS SEVERAL DISTURBANCES INTERACT WITH THE STALLED FRONT. TEMPERATURES THROUGH THE WEEKEND WILL REMAIN ABOVE NORMAL AS ANY COLD AIR REMAINS DISPLACED WELL TO OUR WEST. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... 12 PM UPDATE...ALL THE FREEZING RAIN ADV HAVE EXPIRED AS TEMPS ARE NOW IN THE LOWER TO MIDDLE 30S. IN THE HIGHER ELEVATIONS OF OTSEGO, DELAWARE AND SULLIVAN COUNTIES POCKETS OF FREEZING RAIN ARE STILL POSSIBLE THROUGH EARLY AFTERNOON. 10 AM UPDATE...BASED ON LOCAL MESONET OBS ACROSS NE PA AND PARTS OF THE SOUTHERN TIER AND WESTERN CATSKILLS DECIDED TO EXTEND THE FREEZING RAIN ADV UNTIL MIDDAY. THE HIGHER ELEVATIONS PRIMARILY ABOVE 1200 FT AND THE WESTERN CATSKILLS INCLUDING SULLIVAN COUNTY WILL SEE THE MOST FREEZING RAIN DURING THE NEXT COUPLE OF HOURS. BY EARLY AFTERNOON, COMBINATION OF WARMING ALOFT AND SFC TEMPS RISING ABOVE THE FREEZING MARK WILL END THE FREEZING RAIN THREAT. 830 AM UPDATE...ISSUED FREEZING RAIN ADVISORY FOR TIOGA, BROOME, CHENANGO AND OTSEGO COUNTIES UNTIL 11 AM. LIGHT PRECIP IS NOW SPREADING ACROSS THE ABOVE MENTIONED AREAS WITH TEMPS NEAR FREEZING AND DEW POINTS IN THE LOWER TO MIDDLE 20S. THE LOW DEW POINTS WILL ALLOW TEMPS TO REMAIN STEADY OR DROP SLIGHTLY AS THE LIGHT PRECIP BEGINS WITH AREAS OF FREEZING RAIN LIKELY UNTIL LATE MORNING ESPECIALLY AT THE HIGHER ELEVATIONS. BY LATE MORNING WARM LAYER ALOFT AND DIURNAL HEATING WILL END THE THREAT FOR FREEZING RAIN. 650 AM UPDATE... BASED ON TEMP TRENDS FROM LOCAL MESONET OBSERVATIONS...HAVE ELECTED TO GO WITH AN FREEZING RAIN ADVISORY FOR ALL OF NE PA AND THE CATSKILLS OF EASTERN NY. AS PRECIP CONTINUES TO MOVE IN...CANNOT RULE OUT VERY LIGHT ICE ACCUMULATIONS FOR ELEVATIONS GRATER THAN 1000 FEET. FOR NOW HAVE HELD OFF FOR THE CENTRAL AND EASTERN SOUTHERN TIER AS BULK OF INITIAL BATCH OF RA WILL LIKELY PASS JUST TO THE SOUTH. AFTER THIS...TEMPS SHOULD WARM ABOVE FREEZING HOPEFULLY NEGATING ANY FREEZING RAIN CONCERNS FOR THESE AREAS. NO OTHER SIGNIFICANT CHANGES NEEDED AT THE PRESENT TIME. PREVIOUS NEAR TERM DISCUSSION... MAIN CONCERN IN THE NEAR TERM CONTINUES TO BE APPROACHING FRONTAL WAVE AND ASSOCIATED PRECIP LATER THIS MORNING. LATEST REGIONAL RADAR IMAGES SHOWING LEADING EDGE OF RAIN NOW EAST OF PIT AND WORKING TOWARDS JST IN SW PA. AHEAD OF THIS PRECIP...A SUBSTANTIAL AMOUNT OF DRY AIR REMAINS IN PLACE AS EVIDENCED BY 00Z PIT AND BUF RAOBS. PRECIP IS BEING FORCED LARGELY BY ISENTROPIC ASCENT ALONG THE 285-295 THETA SURFACES AS INCREASING WINDS AT THE 925 AND 850-MB LEVELS ASCEND THE APPROACHING FRONTAL BOUNDARY. WITH THE AMOUNT OF DRY AIR IN PLACE...HAVE ELECTED TO TRIM BACK TIMING OF PRECIP ARRIVAL TIME FROM THE TWIN TIERS AND POINTS SOUTH. IT NOW APPEARS THAT PRECIP WILL NOT MAKE INTO THE CWA BEFORE 12Z AS SUFFICIENT TIME WILL BE REQUIRED TO MOISTEN THE ATMOSPHERIC COLUMN. THE ABOVE SAID...MAIN ATTENTION CONTINUES TO FOCUS ON FZRA POTENTIAL AS INITIAL BATCH OF PRECIP MOVES IN. CLOSE INSPECTION OF BOTH RR AND WRF THETA SURFACES AND MODEL CONDENSATION PRESSURE DEFICITS REVEALS APPROPRIATE SATURATION ALONG THE 285 SFC WILL NOT OCCUR UNTIL 12-13Z AT THE EARLIEST. BY THIS TIME...DIURNAL TEMPS SHOULD BEGIN REBOUNDING AS DAYTIME HEATING COMMENCES WHICH SHOULD ONLY RESULT IN A VERY BRIEF PERIOD WHERE SFC TEMPS MAY BE COLD ENOUGH TO SUPPORT FZRA ALONG THE ELEVATED SURFACES OF THE NORTHERN TIER AND LOWER WYOMING VALLEY REGIONS OF NE PA. BEYOND THIS...RA WILL GRADUALLY OVERSPREAD THE REGION THROUGH THE MORNING AND AFTERNOON HRS. UP NORTH...PRECIP WILL LIKELY HOLD OFF UNTIL EARLY AFTERNOON AFTER WHICH...WEAK SHORTWAVE ENERGY RIDING ALONG THE FRONT SHOULD EVENTUALLY ALLOW PRECIP TO EXTEND AS FAR NORTH AS THE SYR AND RME AREAS. RAINFALL AMOUNTS THROUGH THE DAY WILL LIKELY REMAIN UNDER 2 TENTH OF AN INCH AT MOST LOCATIONS...WITH EVEN LOWER AMOUNTS EXPECTED ACROSS THE NORTHERN FINGER LAKES AND WESTERN MOHAWK VALLEY AS MAX FRONTAL FORCING REMAINS SOUTH. HIGH TEMPS WILL TOP OUT IN LOWER 40S ACROSS THE NORTHERN FINGER LAKES AND LAKE PLAIN...WITH MIDDLE TO UPPER 30S DOMINATE ELSEWHERE. && .SHORT TERM /6 PM THIS EVENING THROUGH SUNDAY NIGHT/... FAIRLY ACTIVE PERIOD CONTINUING TO TAKE SHAPE THROUGH THE UPCOMING WEEKEND AS THE NEXT IN A SERIES OF SFC LOWS LIFTS NORTH ALONG A STALLED FRONT TO OUR WEST BEGINNING TONIGHT. THAT SAID...RA ACROSS THE REGION SHOULD BECOME A LITTLE BIT MORE ORGANIZED INITIALLY THIS EVENING AS SFC LOW LIFTS NORTH FROM THE LWR OHIO VLY INTO THE LWR GREAT LAKES. AS THIS OCCURS...FORCING CONTRIBUTIONS FROM BOTH THE POLAR AND SUBTROPICAL JETS WILL TRANSCEND ACROSS THE REGION WITH ADDITIONAL FORCING ARRIVING FROM CONTINUED ISENTROPIC ASCENT ALONG THE PREVIOUSLY MENTIONED WARM FRONT. THERMAL PROFILES FROM ACROSS THE REGION INDICATE SFC TEMPS WILL REMAIN ABOVE FREEZING AS WARM AIR ADVECTION CONTINUES. THIS SHOULD KEEP ANY PRECIP IN LIQUID FORM. SFC LOW PROGGED TO PASS TO OUR WEST ON SATURDAY WITH INCREASING SOUTHWESTERLY FLOW FINALLY ALLOWING WARM FRONT TO LIFT NORTH THROUGH THE ENTIRE CWA. AS A RESULT...EXPECT A WARMER DAY WITH TEMPS TOPPING OUT IN THE UPPER 40S TO LOWER 50S ACROSS MUCH OF THE AREA. WITH BEST FORCING FOR ASCENT ARRIVING FROM A NORTHERN STREAM SHORTWAVE ACROSS THE UPPER GREAT LAKES...BEST CHANCES FOR ORGANIZED PRECIP WILL LIKELY REMAIN NORTH AND WEST OF OUR AREA. DESPITE THIS HOWEVER...SHORT TERM MODELS INDICATE A DEVELOPING SECONDARY LOW OFF THE NJ COAST THROUGH THE DAY WHICH COMBINED WITH A WEAKER SHORTWAVE IMPULSE PASSING OVERHEAD SHOULD KEEP THE CHC FOR SHWRS ACROSS THE AREA THROUGH THE DAY. MAIN LOW EXPECTED TO PASS TO OUR NORTH OVERNIGHT WHICH WILL SEND A COLD FRONT SOUTH ACROSS THE FCST AREA. MODELS AGREE A QUICK COOL DOWN WILL OCCUR AFTER PASSAGE WITH 850-MB TEMPS QUICKLY FALLING TO -4C ACROSS THE FAR NORTH. HIGHLY SHEARED FLOW COMBINED WITH THE INFLUX OF DRY AIR AND ONLY MARGINAL TEMP DIFFERENCES WILL NEGATE ANY LAKE RESPONSE AND THUS HAVE DRIED THINGS OUT FROM NORTH TO SOUTH OVERNIGHT EARLY SUN. NEXT MORE POTENT WAVE TO LIFT NORTH FROM THE OHIO VLY ON SUN WHICH WILL ONCE AGAIN LIFT THE FRONT BACK NORTH THROUGH BEGINNING SUN NGT. AS SUCH...EXPECT INCREASING CHANCES FOR RAIN ONCE AGAIN SUN AFTERNOON AND EVENING. && .LONG TERM /MONDAY THROUGH THURSDAY/... LOW PRES WILL TRACK NEWD INTO ERN CANADA ON MONDAY...SWINGING A CDFNT THUR THE RGN. AFTER FROPA...SOME LINGERING -SHSN WILL BE PSBL IN THE NW FLOW ON TUE ACRS CNTRL NY. OTRW...A DRY PD XPCTD AS HI PRES SETS UP OVER THE MID ATLC RGN WITH TEMPS AVERAGING ARND OR SLIGHTLY ABV SEASONAL NORMS. UTILIZED HPC GRIDS FOR THE MED RNG FCST BUT TRENDED MORE OPTIMISTIC FOR CLD CVR GIVEN LATEST GUIDANCE. && .AVIATION /18Z FRIDAY THROUGH WEDNESDAY/... WDSPRD IFR/MVFR XPCTD AT ALL SITES THRU 18Z SAT IN -RA/DZ/BR/CIGS. AT 18Z SYR/RME ARE STILL VFR BUT XPCT MVFR CIGS TO MOV INTO THAT AREA AFTER 21Z. ELSEWHERE IFR/MVFR FIRMLY ENTRENCHED ACRS THE FCST AREA...AND CONDITIONS AT MOST LOCATIONS ACRS THE SRN TIER AND NE PA WILL GO BLO AIRPORT MINS. 2ND WAVE LATER TNGT WILL DELIVER ANOTHER ROUND OF RAIN...WITH MOST OF THE STEADIER PCPN EXITING THE RGN BY DAYBREAK WITH RESIDUAL LOW CIGS/-DZ PERSISTING INTO THE EARLY AFTN HRS. WINDS WILL BE ON THE LGT SIDE...GNRLY FROM THE S OR SE ARND 5 KTS. OUTLOOK... SATURDAY NIGHT...MVFR MAINLY ACRS CNTRL NY. SUNDAY...VFR. SUNDAY NIGHT/MON...IFR/MVFR IN RAIN. TUESDAY...PATCHY MVFR ACRS CNTRL NY. WED...VFR. && .BGM WATCHES/WARNINGS/ADVISORIES... PA...NONE. NY...NONE. && $$ SYNOPSIS...CMG/RRM NEAR TERM...CMG/RRM SHORT TERM...CMG
AREA FORECAST DISCUSSION
NWS BINGHAMTON NY
1215 PM EST FRI DEC 7 2012 .SYNOPSIS... A WARM FRONT WILL BRING RAIN TO MUCH OF THE REGION TODAY. THIS WILL MARK THE BEGINNING OF A RATHER UNSETTLED PERIOD WITH SCATTERED SHOWERS POSSIBLE EACH DAY AS SEVERAL DISTURBANCES INTERACT WITH THE STALLED FRONT. TEMPERATURES THROUGH THE WEEKEND WILL REMAIN ABOVE NORMAL AS ANY COLD AIR REMAINS DISPLACED WELL TO OUR WEST. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... 12 PM UPDATE...ALL THE FREEZING RAIN ADV HAVE EXPIRED AS TEMPS ARE NOW IN THE LOWER TO MIDDLE 30S. IN THE HIGHER ELEVATIONS OF OTSEGO, DELAWARE AND SULLIVAN COUNTIES POCKETS OF FREEZING RAIN ARE STILL POSSIBLE THROUGH EARLY AFTERNOON. 10 AM UPDATE...BASED ON LOCAL MESONET OBS ACROSS NE PA AND PARTS OF THE SOUTHERN TIER AND WESTERN CATSKILLS DECIDED TO EXTEND THE FREEZING RAIN ADV UNTIL MIDDAY. THE HIGHER ELEVATIONS PRIMARILY ABOVE 1200 FT AND THE WESTERN CATSKILLS INCLUDING SULLIVAN COUNTY WILL SEE THE MOST FREEZING RAIN DURING THE NEXT COUPLE OF HOURS. BY EARLY AFTERNOON, COMBINATION OF WARMING ALOFT AND SFC TEMPS RISING ABOVE THE FREEZING MARK WILL END THE FREEZING RAIN THREAT. 830 AM UPDATE...ISSUED FREEZING RAIN ADVISORY FOR TIOGA, BROOME, CHENANGO AND OTSEGO COUNTIES UNTIL 11 AM. LIGHT PRECIP IS NOW SPREADING ACROSS THE ABOVE MENTIONED AREAS WITH TEMPS NEAR FREEZING AND DEW POINTS IN THE LOWER TO MIDDLE 20S. THE LOW DEW POINTS WILL ALLOW TEMPS TO REMAIN STEADY OR DROP SLIGHTLY AS THE LIGHT PRECIP BEGINS WITH AREAS OF FREEZING RAIN LIKELY UNTIL LATE MORNING ESPECIALLY AT THE HIGHER ELEVATIONS. BY LATE MORNING WARM LAYER ALOFT AND DIURNAL HEATING WILL END THE THREAT FOR FREEZING RAIN. 650 AM UPDATE... BASED ON TEMP TRENDS FROM LOCAL MESONET OBSERVATIONS...HAVE ELECTED TO GO WITH AN FREEZING RAIN ADVISORY FOR ALL OF NE PA AND THE CATSKILLS OF EASTERN NY. AS PRECIP CONTINUES TO MOVE IN...CANNOT RULE OUT VERY LIGHT ICE ACCUMULATIONS FOR ELEVATIONS GRATER THAN 1000 FEET. FOR NOW HAVE HELD OFF FOR THE CENTRAL AND EASTERN SOUTHERN TIER AS BULK OF INITIAL BATCH OF RA WILL LIKELY PASS JUST TO THE SOUTH. AFTER THIS...TEMPS SHOULD WARM ABOVE FREEZING HOPEFULLY NEGATING ANY FREEZING RAIN CONCERNS FOR THESE AREAS. NO OTHER SIGNIFICANT CHANGES NEEDED AT THE PRESENT TIME. PREVIOUS NEAR TERM DISCUSSION... MAIN CONCERN IN THE NEAR TERM CONTINUES TO BE APPROACHING FRONTAL WAVE AND ASSOCIATED PRECIP LATER THIS MORNING. LATEST REGIONAL RADAR IMAGES SHOWING LEADING EDGE OF RAIN NOW EAST OF PIT AND WORKING TOWARDS JST IN SW PA. AHEAD OF THIS PRECIP...A SUBSTANTIAL AMOUNT OF DRY AIR REMAINS IN PLACE AS EVIDENCED BY 00Z PIT AND BUF RAOBS. PRECIP IS BEING FORCED LARGELY BY ISENTROPIC ASCENT ALONG THE 285-295 THETA SURFACES AS INCREASING WINDS AT THE 925 AND 850-MB LEVELS ASCEND THE APPROACHING FRONTAL BOUNDARY. WITH THE AMOUNT OF DRY AIR IN PLACE...HAVE ELECTED TO TRIM BACK TIMING OF PRECIP ARRIVAL TIME FROM THE TWIN TIERS AND POINTS SOUTH. IT NOW APPEARS THAT PRECIP WILL NOT MAKE INTO THE CWA BEFORE 12Z AS SUFFICIENT TIME WILL BE REQUIRED TO MOISTEN THE ATMOSPHERIC COLUMN. THE ABOVE SAID...MAIN ATTENTION CONTINUES TO FOCUS ON FZRA POTENTIAL AS INITIAL BATCH OF PRECIP MOVES IN. CLOSE INSPECTION OF BOTH RR AND WRF THETA SURFACES AND MODEL CONDENSATION PRESSURE DEFICITS REVEALS APPROPRIATE SATURATION ALONG THE 285 SFC WILL NOT OCCUR UNTIL 12-13Z AT THE EARLIEST. BY THIS TIME...DIURNAL TEMPS SHOULD BEGIN REBOUNDING AS DAYTIME HEATING COMMENCES WHICH SHOULD ONLY RESULT IN A VERY BRIEF PERIOD WHERE SFC TEMPS MAY BE COLD ENOUGH TO SUPPORT FZRA ALONG THE ELEVATED SURFACES OF THE NORTHERN TIER AND LOWER WYOMING VALLEY REGIONS OF NE PA. BEYOND THIS...RA WILL GRADUALLY OVERSPREAD THE REGION THROUGH THE MORNING AND AFTERNOON HRS. UP NORTH...PRECIP WILL LIKELY HOLD OFF UNTIL EARLY AFTERNOON AFTER WHICH...WEAK SHORTWAVE ENERGY RIDING ALONG THE FRONT SHOULD EVENTUALLY ALLOW PRECIP TO EXTEND AS FAR NORTH AS THE SYR AND RME AREAS. RAINFALL AMOUNTS THROUGH THE DAY WILL LIKELY REMAIN UNDER 2 TENTH OF AN INCH AT MOST LOCATIONS...WITH EVEN LOWER AMOUNTS EXPECTED ACROSS THE NORTHERN FINGER LAKES AND WESTERN MOHAWK VALLEY AS MAX FRONTAL FORCING REMAINS SOUTH. HIGH TEMPS WILL TOP OUT IN LOWER 40S ACROSS THE NORTHERN FINGER LAKES AND LAKE PLAIN...WITH MIDDLE TO UPPER 30S DOMINATE ELSEWHERE. && .SHORT TERM /6 PM THIS EVENING THROUGH SUNDAY NIGHT/... FAIRLY ACTIVE PERIOD CONTINUING TO TAKE SHAPE THROUGH THE UPCOMING WEEKEND AS THE NEXT IN A SERIES OF SFC LOWS LIFTS NORTH ALONG A STALLED FRONT TO OUR WEST BEGINNING TONIGHT. THAT SAID...RA ACROSS THE REGION SHOULD BECOME A LITTLE BIT MORE ORGANIZED INITIALLY THIS EVENING AS SFC LOW LIFTS NORTH FROM THE LWR OHIO VLY INTO THE LWR GREAT LAKES. AS THIS OCCURS...FORCING CONTRIBUTIONS FROM BOTH THE POLAR AND SUBTROPICAL JETS WILL TRANSCEND ACROSS THE REGION WITH ADDITIONAL FORCING ARRIVING FROM CONTINUED ISENTROPIC ASCENT ALONG THE PREVIOUSLY MENTIONED WARM FRONT. THERMAL PROFILES FROM ACROSS THE REGION INDICATE SFC TEMPS WILL REMAIN ABOVE FREEZING AS WARM AIR ADVECTION CONTINUES. THIS SHOULD KEEP ANY PRECIP IN LIQUID FORM. SFC LOW PROGGED TO PASS TO OUR WEST ON SATURDAY WITH INCREASING SOUTHWESTERLY FLOW FINALLY ALLOWING WARM FRONT TO LIFT NORTH THROUGH THE ENTIRE CWA. AS A RESULT...EXPECT A WARMER DAY WITH TEMPS TOPPING OUT IN THE UPPER 40S TO LOWER 50S ACROSS MUCH OF THE AREA. WITH BEST FORCING FOR ASCENT ARRIVING FROM A NORTHERN STREAM SHORTWAVE ACROSS THE UPPER GREAT LAKES...BEST CHANCES FOR ORGANIZED PRECIP WILL LIKELY REMAIN NORTH AND WEST OF OUR AREA. DESPITE THIS HOWEVER...SHORT TERM MODELS INDICATE A DEVELOPING SECONDARY LOW OFF THE NJ COAST THROUGH THE DAY WHICH COMBINED WITH A WEAKER SHORTWAVE IMPULSE PASSING OVERHEAD SHOULD KEEP THE CHC FOR SHWRS ACROSS THE AREA THROUGH THE DAY. MAIN LOW EXPECTED TO PASS TO OUR NORTH OVERNIGHT WHICH WILL SEND A COLD FRONT SOUTH ACROSS THE FCST AREA. MODELS AGREE A QUICK COOL DOWN WILL OCCUR AFTER PASSAGE WITH 850-MB TEMPS QUICKLY FALLING TO -4C ACROSS THE FAR NORTH. HIGHLY SHEARED FLOW COMBINED WITH THE INFLUX OF DRY AIR AND ONLY MARGINAL TEMP DIFFERENCES WILL NEGATE ANY LAKE RESPONSE AND THUS HAVE DRIED THINGS OUT FROM NORTH TO SOUTH OVERNIGHT EARLY SUN. NEXT MORE POTENT WAVE TO LIFT NORTH FROM THE OHIO VLY ON SUN WHICH WILL ONCE AGAIN LIFT THE FRONT BACK NORTH THROUGH BEGINNING SUN NGT. AS SUCH...EXPECT INCREASING CHANCES FOR RAIN ONCE AGAIN SUN AFTERNOON AND EVENING. && .LONG TERM /MONDAY THROUGH THURSDAY/... 430 AM UPDATE... NO CHGS NEEDED TO LONG TERM AT THIS TIME AS FRONT MVS THRU MON EVNG WITH LKLY RAIN SHOWERS. NW FLOW KICKS IN FOLLOWING FROPA TO RESULT IN LK EFFECT PCPN. BOTH 12Z AND NOW 00Z EC INDICATE DVLPNG SFC LOPRES RIDING UP ALONG SFC BNDRY JUST OFF THE EAST COAST BY EARLY WEEK, ALTHO NO OTHER MED RANGE MODELS HV THIS FEATURE. PREV DISCUSSION BLO... MEDIUM RANGE MODELS CONTINUE TO SHOW FAIR AGREEMENT THROUGH THE EXTENDED PERIOD. SUNDAY NIGHT THROUGH MONDAY, SFC LOW PRES WILL TRACK FROM THE OHIO VALLEY NORTHEAST ACROSS LAKE ERIE INTO NEARBY SOUTHERN ONTARIO. WILL CARRY LIKELY POPS BOTH PERIODS WITH RAIN LIKELY SUNDAY NIGHT FOLLOWED BY RAIN SHOWERS ON MONDAY AS TRAILING COLD FRONT CROSSES AREA MONDAY AFTERNOON AND EVENING. THROUGH MONDAY EVENING TEMPS WILL REMAIN WARM ENOUGH FOR JUST LIQUID PRECIP TO FALL. MONDAY NIGHT AS TEMPS LOWER UNDER CAA AND NORTHWEST FLOW, A WEAK LAKE RESPONSE MAY OCCUR INTO TUESDAY. TUESDAY NIGHT THROUGH THURSDAY, LOOKS DRY WITH SFC HIGH PRES STRETCHING FROM THE MID ATLANTIC REGION INTO NEW ENGLAND. TEMPS THROUGH THE PERIOD WILL START WELL ABOVE NORMAL THEN FALL TO SEASONAL LEVELS TUESDAY AND WEDNESDAY BEFORE MODERATING AGAIN ON THURSDAY. && .AVIATION /17Z FRIDAY THROUGH TUESDAY/... 12Z UPDATE... VFR INITIALLY WILL GIVE WAY TO MVFR CIGS LATE THIS MORNING. AS PCPN MOVES FROM SOUTH TO NORTH IT WILL BRING MVFR VSBYS TO TERMINALS AFTER 18Z. LIGHT RAIN WILL CONTINUE THROUGH THE DAY WITH MVFR CONDITIONS EXPECTED. HIGHER TERMINALS WILL LIKELY SEE THESE CIGS DECREASE TO IFR AFTER 05Z AS LOW LEVEL MOISTURE REMAINS ENTRENCHED ACROSS THE AREA. SOUTH WINDS AROUND 5 KTS WILL INCREASE TO NEAR 10KTS THIS AFTERNOON THEN DIMINISH TO LGT/VRB AFTER 06Z. OUTLOOK... SATURDAY...MVFR IN SHRA. SATURDAY NIGHT/SUNDAY MORNING...PRIMARILY VFR. SUNDAY AFTERNOON THROUGH MONDAY EVENING...RESTRICTIONS EXPECTED IN RAIN. TUESDAY...VFR. && .BGM WATCHES/WARNINGS/ADVISORIES... PA...NONE. NY...NONE. && $$ SYNOPSIS...CMG/RRM NEAR TERM...CMG/RRM SHORT TERM...CMG LONG TERM...PVN/RRM AVIATION...PVN
AREA FORECAST DISCUSSION
NWS BINGHAMTON NY
1010 AM EST FRI DEC 7 2012 .SYNOPSIS... A WARM FRONT WILL BRING RAIN TO MUCH OF THE REGION TODAY. AREAS OF FREEZING RAIN ARE LIKELY IN THE HIGHER ELEVATIONS UNTIL NOON ACROSS NORTHEAST PENNSYLVANIA, THE SOUTHERN TIER AND CATSKILLS. THIS WILL MARK THE BEGINNING OF A RATHER UNSETTLED PERIOD WITH SCATTERED SHOWERS POSSIBLE EACH DAY AS SEVERAL DISTURBANCES INTERACT WITH THE STALLED FRONT. TEMPERATURES THROUGH THE WEEKEND WILL REMAIN ABOVE NORMAL AS ANY COLD AIR REMAINS DISPLACED WELL TO OUR WEST. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... 10 AM UPDATE...BASED ON LOCAL MESONET OBS ACROSS NE PA AND PARTS OF THE SOUTHERN TIER AND WESTERN CATSKILLS DECIDED TO EXTEND THE FREEZING RAIN ADV UNTIL MIDDAY. THE HIGHER ELEVATIONS PRIMARILY ABOVE 1200 FT AND THE WESTERN CATSKILLS INCLUDING SULLIVAN COUNTY WILL SEE THE MOST FREEZING RAIN DURING THE NEXT COUPLE OF HOURS. BY EARLY AFTERNOON, COMBINATION OF WARMING ALOFT AND SFC TEMPS RISING ABOVE THE FREEZING MARK WILL END THE FREEZING RAIN THREAT. 830 AM UPDATE...ISSUED FREEZING RAIN ADVISORY FOR TIOGA, BROOME, CHENANGO AND OTSEGO COUNTIES UNTIL 11 AM. LIGHT PRECIP IS NOW SPREADING ACROSS THE ABOVE MENTIONED AREAS WITH TEMPS NEAR FREEZING AND DEW POINTS IN THE LOWER TO MIDDLE 20S. THE LOW DEW POINTS WILL ALLOW TEMPS TO REMAIN STEADY OR DROP SLIGHTLY AS THE LIGHT PRECIP BEGINS WITH AREAS OF FREEZING RAIN LIKELY UNTIL LATE MORNING ESPECIALLY AT THE HIGHER ELEVATIONS. BY LATE MORNING WARM LAYER ALOFT AND DIURNAL HEATING WILL END THE THREAT FOR FREEZING RAIN. 650 AM UPDATE... BASED ON TEMP TRENDS FROM LOCAL MESONET OBSERVATIONS...HAVE ELECTED TO GO WITH AN FREEZING RAIN ADVISORY FOR ALL OF NE PA AND THE CATSKILLS OF EASTERN NY. AS PRECIP CONTINUES TO MOVE IN...CANNOT RULE OUT VERY LIGHT ICE ACCUMULATIONS FOR ELEVATIONS GRATER THAN 1000 FEET. FOR NOW HAVE HELD OFF FOR THE CENTRAL AND EASTERN SOUTHERN TIER AS BULK OF INITIAL BATCH OF RA WILL LIKELY PASS JUST TO THE SOUTH. AFTER THIS...TEMPS SHOULD WARM ABOVE FREEZING HOPEFULLY NEGATING ANY FREEZING RAIN CONCERNS FOR THESE AREAS. NO OTHER SIGNIFICANT CHANGES NEEDED AT THE PRESENT TIME. PREVIOUS NEAR TERM DISCUSSION... MAIN CONCERN IN THE NEAR TERM CONTINUES TO BE APPROACHING FRONTAL WAVE AND ASSOCIATED PRECIP LATER THIS MORNING. LATEST REGIONAL RADAR IMAGES SHOWING LEADING EDGE OF RAIN NOW EAST OF PIT AND WORKING TOWARDS JST IN SW PA. AHEAD OF THIS PRECIP...A SUBSTANTIAL AMOUNT OF DRY AIR REMAINS IN PLACE AS EVIDENCED BY 00Z PIT AND BUF RAOBS. PRECIP IS BEING FORCED LARGELY BY ISENTROPIC ASCENT ALONG THE 285-295 THETA SURFACES AS INCREASING WINDS AT THE 925 AND 850-MB LEVELS ASCEND THE APPROACHING FRONTAL BOUNDARY. WITH THE AMOUNT OF DRY AIR IN PLACE...HAVE ELECTED TO TRIM BACK TIMING OF PRECIP ARRIVAL TIME FROM THE TWIN TIERS AND POINTS SOUTH. IT NOW APPEARS THAT PRECIP WILL NOT MAKE INTO THE CWA BEFORE 12Z AS SUFFICIENT TIME WILL BE REQUIRED TO MOISTEN THE ATMOSPHERIC COLUMN. THE ABOVE SAID...MAIN ATTENTION CONTINUES TO FOCUS ON FZRA POTENTIAL AS INITIAL BATCH OF PRECIP MOVES IN. CLOSE INSPECTION OF BOTH RR AND WRF THETA SURFACES AND MODEL CONDENSATION PRESSURE DEFICITS REVEALS APPROPRIATE SATURATION ALONG THE 285 SFC WILL NOT OCCUR UNTIL 12-13Z AT THE EARLIEST. BY THIS TIME...DIURNAL TEMPS SHOULD BEGIN REBOUNDING AS DAYTIME HEATING COMMENCES WHICH SHOULD ONLY RESULT IN A VERY BRIEF PERIOD WHERE SFC TEMPS MAY BE COLD ENOUGH TO SUPPORT FZRA ALONG THE ELEVATED SURFACES OF THE NORTHERN TIER AND LOWER WYOMING VALLEY REGIONS OF NE PA. BEYOND THIS...RA WILL GRADUALLY OVERSPREAD THE REGION THROUGH THE MORNING AND AFTERNOON HRS. UP NORTH...PRECIP WILL LIKELY HOLD OFF UNTIL EARLY AFTERNOON AFTER WHICH...WEAK SHORTWAVE ENERGY RIDING ALONG THE FRONT SHOULD EVENTUALLY ALLOW PRECIP TO EXTEND AS FAR NORTH AS THE SYR AND RME AREAS. RAINFALL AMOUNTS THROUGH THE DAY WILL LIKELY REMAIN UNDER 2 TENTH OF AN INCH AT MOST LOCATIONS...WITH EVEN LOWER AMOUNTS EXPECTED ACROSS THE NORTHERN FINGER LAKES AND WESTERN MOHAWK VALLEY AS MAX FRONTAL FORCING REMAINS SOUTH. HIGH TEMPS WILL TOP OUT IN LOWER 40S ACROSS THE NORTHERN FINGER LAKES AND LAKE PLAIN...WITH MIDDLE TO UPPER 30S DOMINATE ELSEWHERE. && .SHORT TERM /6 PM THIS EVENING THROUGH SUNDAY NIGHT/... FAIRLY ACTIVE PERIOD CONTINUING TO TAKE SHAPE THROUGH THE UPCOMING WEEKEND AS THE NEXT IN A SERIES OF SFC LOWS LIFTS NORTH ALONG A STALLED FRONT TO OUR WEST BEGINNING TONIGHT. THAT SAID...RA ACROSS THE REGION SHOULD BECOME A LITTLE BIT MORE ORGANIZED INITIALLY THIS EVENING AS SFC LOW LIFTS NORTH FROM THE LWR OHIO VLY INTO THE LWR GREAT LAKES. AS THIS OCCURS...FORCING CONTRIBUTIONS FROM BOTH THE POLAR AND SUBTROPICAL JETS WILL TRANSCEND ACROSS THE REGION WITH ADDITIONAL FORCING ARRIVING FROM CONTINUED ISENTROPIC ASCENT ALONG THE PREVIOUSLY MENTIONED WARM FRONT. THERMAL PROFILES FROM ACROSS THE REGION INDICATE SFC TEMPS WILL REMAIN ABOVE FREEZING AS WARM AIR ADVECTION CONTINUES. THIS SHOULD KEEP ANY PRECIP IN LIQUID FORM. SFC LOW PROGGED TO PASS TO OUR WEST ON SATURDAY WITH INCREASING SOUTHWESTERLY FLOW FINALLY ALLOWING WARM FRONT TO LIFT NORTH THROUGH THE ENTIRE CWA. AS A RESULT...EXPECT A WARMER DAY WITH TEMPS TOPPING OUT IN THE UPPER 40S TO LOWER 50S ACROSS MUCH OF THE AREA. WITH BEST FORCING FOR ASCENT ARRIVING FROM A NORTHERN STREAM SHORTWAVE ACROSS THE UPPER GREAT LAKES...BEST CHANCES FOR ORGANIZED PRECIP WILL LIKELY REMAIN NORTH AND WEST OF OUR AREA. DESPITE THIS HOWEVER...SHORT TERM MODELS INDICATE A DEVELOPING SECONDARY LOW OFF THE NJ COAST THROUGH THE DAY WHICH COMBINED WITH A WEAKER SHORTWAVE IMPULSE PASSING OVERHEAD SHOULD KEEP THE CHC FOR SHWRS ACROSS THE AREA THROUGH THE DAY. MAIN LOW EXPECTED TO PASS TO OUR NORTH OVERNIGHT WHICH WILL SEND A COLD FRONT SOUTH ACROSS THE FCST AREA. MODELS AGREE A QUICK COOL DOWN WILL OCCUR AFTER PASSAGE WITH 850-MB TEMPS QUICKLY FALLING TO -4C ACROSS THE FAR NORTH. HIGHLY SHEARED FLOW COMBINED WITH THE INFLUX OF DRY AIR AND ONLY MARGINAL TEMP DIFFERENCES WILL NEGATE ANY LAKE RESPONSE AND THUS HAVE DRIED THINGS OUT FROM NORTH TO SOUTH OVERNIGHT EARLY SUN. NEXT MORE POTENT WAVE TO LIFT NORTH FROM THE OHIO VLY ON SUN WHICH WILL ONCE AGAIN LIFT THE FRONT BACK NORTH THROUGH BEGINNING SUN NGT. AS SUCH...EXPECT INCREASING CHANCES FOR RAIN ONCE AGAIN SUN AFTERNOON AND EVENING. && .LONG TERM /MONDAY THROUGH THURSDAY/... 430 AM UPDATE... NO CHGS NEEDED TO LONG TERM AT THIS TIME AS FRONT MVS THRU MON EVNG WITH LKLY RAIN SHOWERS. NW FLOW KICKS IN FOLLOWING FROPA TO RESULT IN LK EFFECT PCPN. BOTH 12Z AND NOW 00Z EC INDICATE DVLPNG SFC LOPRES RIDING UP ALONG SFC BNDRY JUST OFF THE EAST COAST BY EARLY WEEK, ALTHO NO OTHER MED RANGE MODELS HV THIS FEATURE. PREV DISCUSSION BLO... MEDIUM RANGE MODELS CONTINUE TO SHOW FAIR AGREEMENT THROUGH THE EXTENDED PERIOD. SUNDAY NIGHT THROUGH MONDAY, SFC LOW PRES WILL TRACK FROM THE OHIO VALLEY NORTHEAST ACROSS LAKE ERIE INTO NEARBY SOUTHERN ONTARIO. WILL CARRY LIKELY POPS BOTH PERIODS WITH RAIN LIKELY SUNDAY NIGHT FOLLOWED BY RAIN SHOWERS ON MONDAY AS TRAILING COLD FRONT CROSSES AREA MONDAY AFTERNOON AND EVENING. THROUGH MONDAY EVENING TEMPS WILL REMAIN WARM ENOUGH FOR JUST LIQUID PRECIP TO FALL. MONDAY NIGHT AS TEMPS LOWER UNDER CAA AND NORTHWEST FLOW, A WEAK LAKE RESPONSE MAY OCCUR INTO TUESDAY. TUESDAY NIGHT THROUGH THURSDAY, LOOKS DRY WITH SFC HIGH PRES STRETCHING FROM THE MID ATLANTIC REGION INTO NEW ENGLAND. TEMPS THROUGH THE PERIOD WILL START WELL ABOVE NORMAL THEN FALL TO SEASONAL LEVELS TUESDAY AND WEDNESDAY BEFORE MODERATING AGAIN ON THURSDAY. && .AVIATION /15Z FRIDAY THROUGH TUESDAY/... 12Z UPDATE... VFR INITIALLY WILL GIVE WAY TO MVFR CIGS LATE THIS MORNING. AS PCPN MOVES FROM SOUTH TO NORTH IT WILL BRING MVFR VSBYS TO TERMINALS AFTER 18Z. LIGHT RAIN WILL CONTINUE THROUGH THE DAY WITH MVFR CONDITIONS EXPECTED. HIGHER TERMINALS WILL LIKELY SEE THESE CIGS DECREASE TO IFR AFTER 05Z AS LOW LEVEL MOISTURE REMAINS ENTRENCHED ACROSS THE AREA. SOUTH WINDS AROUND 5 KTS WILL INCREASE TO NEAR 10KTS THIS AFTERNOON THEN DIMINISH TO LGT/VRB AFTER 06Z. OUTLOOK... SATURDAY...MVFR IN SHRA. SATURDAY NIGHT/SUNDAY MORNING...PRIMARILY VFR. SUNDAY AFTERNOON THROUGH MONDAY EVENING...RESTRICTIONS EXPECTED IN RAIN. TUESDAY...VFR. && .BGM WATCHES/WARNINGS/ADVISORIES... PA...FREEZING RAIN ADVISORY UNTIL NOON EST TODAY FOR PAZ038>040-043- 044-047-048-072. NY...FREEZING RAIN ADVISORY UNTIL NOON EST TODAY FOR NYZ045-046- 055>057-062. && $$ SYNOPSIS...CMG/RRM NEAR TERM...CMG/RRM SHORT TERM...CMG LONG TERM...PVN/RRM AVIATION...PVN
AREA FORECAST DISCUSSION
NWS BINGHAMTON NY
837 AM EST FRI DEC 7 2012 .SYNOPSIS... AN APPROACHING WARM FRONT WILL LEAD TO SCATTERED SHOWERS ACROSS THE REGION TODAY. AREAS OF FREEZING RAIN ARE LIKELY IN THE HIGHER ELEVATIONS THROUGH LATE MORNING ACROSS NORTHEAST PENNSYLVANIA, THE SOUTHERN TIER AND CATSKILLS. THIS WILL MARK THE BEGINNING OF A RATHER UNSETTLED PERIOD WITH SCATTERED SHOWERS POSSIBLE EACH DAY AS SEVERAL DISTURBANCES INTERACT WITH THE STALLED FRONT. TEMPERATURES THROUGH THE WEEKEND WILL REMAIN ABOVE NORMAL AS ANY COLD AIR REMAINS DISPLACED WELL TO OUR WEST. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... 830 AM UPDATE...ISSUED FREEZING RAIN ADVISORY FOR TIOGA, BROOME, CHENANGO AND OTSEGO COUNTIES UNTIL 11 AM. LIGHT PRECIP IS NOW SPREADING ACROSS THE ABOVE MENTIONED AREAS WITH TEMPS NEAR FREEZING AND DEW POINTS IN THE LOWER TO MIDDLE 20S. THE LOW DEW POINTS WILL ALLOW TEMPS TO REMAIN STEADY OR DROP SLIGHTLY AS THE LIGHT PRECIP BEGINS WITH AREAS OF FREEZING RAIN LIKELY UNTIL LATE MORNING ESPECIALLY AT THE HIGHER ELEVATIONS. BY LATE MORNING WARM LAYER ALOFT AND DIURNAL HEATING WILL END THE THREAT FOR FREEZING RAIN. 650 AM UPDATE... BASED ON TEMP TRENDS FROM LOCAL MESONET OBSERVATIONS...HAVE ELECTED TO GO WITH AN FREEZING RAIN ADVISORY FOR ALL OF NE PA AND THE CATSKILLS OF EASTERN NY. AS PRECIP CONTINUES TO MOVE IN...CANNOT RULE OUT VERY LIGHT ICE ACCUMULATIONS FOR ELEVATIONS GRATER THAN 1000 FEET. FOR NOW HAVE HELD OFF FOR THE CENTRAL AND EASTERN SOUTHERN TIER AS BULK OF INITIAL BATCH OF RA WILL LIKELY PASS JUST TO THE SOUTH. AFTER THIS...TEMPS SHOULD WARM ABOVE FREEZING HOPEFULLY NEGATING ANY FREEZING RAIN CONCERNS FOR THESE AREAS. NO OTHER SIGNIFICANT CHANGES NEEDED AT THE PRESENT TIME. PREVIOUS NEAR TERM DISCUSSION... MAIN CONCERN IN THE NEAR TERM CONTINUES TO BE APPROACHING FRONTAL WAVE AND ASSOCIATED PRECIP LATER THIS MORNING. LATEST REGIONAL RADAR IMAGES SHOWING LEADING EDGE OF RAIN NOW EAST OF PIT AND WORKING TOWARDS JST IN SW PA. AHEAD OF THIS PRECIP...A SUBSTANTIAL AMOUNT OF DRY AIR REMAINS IN PLACE AS EVIDENCED BY 00Z PIT AND BUF RAOBS. PRECIP IS BEING FORCED LARGELY BY ISENTROPIC ASCENT ALONG THE 285-295 THETA SURFACES AS INCREASING WINDS AT THE 925 AND 850-MB LEVELS ASCEND THE APPROACHING FRONTAL BOUNDARY. WITH THE AMOUNT OF DRY AIR IN PLACE...HAVE ELECTED TO TRIM BACK TIMING OF PRECIP ARRIVAL TIME FROM THE TWIN TIERS AND POINTS SOUTH. IT NOW APPEARS THAT PRECIP WILL NOT MAKE INTO THE CWA BEFORE 12Z AS SUFFICIENT TIME WILL BE REQUIRED TO MOISTEN THE ATMOSPHERIC COLUMN. THE ABOVE SAID...MAIN ATTENTION CONTINUES TO FOCUS ON FZRA POTENTIAL AS INITIAL BATCH OF PRECIP MOVES IN. CLOSE INSPECTION OF BOTH RR AND WRF THETA SURFACES AND MODEL CONDENSATION PRESSURE DEFICITS REVEALS APPROPRIATE SATURATION ALONG THE 285 SFC WILL NOT OCCUR UNTIL 12-13Z AT THE EARLIEST. BY THIS TIME...DIURNAL TEMPS SHOULD BEGIN REBOUNDING AS DAYTIME HEATING COMMENCES WHICH SHOULD ONLY RESULT IN A VERY BRIEF PERIOD WHERE SFC TEMPS MAY BE COLD ENOUGH TO SUPPORT FZRA ALONG THE ELEVATED SURFACES OF THE NORTHERN TIER AND LOWER WYOMING VALLEY REGIONS OF NE PA. BEYOND THIS...RA WILL GRADUALLY OVERSPREAD THE REGION THROUGH THE MORNING AND AFTERNOON HRS. UP NORTH...PRECIP WILL LIKELY HOLD OFF UNTIL EARLY AFTERNOON AFTER WHICH...WEAK SHORTWAVE ENERGY RIDING ALONG THE FRONT SHOULD EVENTUALLY ALLOW PRECIP TO EXTEND AS FAR NORTH AS THE SYR AND RME AREAS. RAINFALL AMOUNTS THROUGH THE DAY WILL LIKELY REMAIN UNDER 2 TENTH OF AN INCH AT MOST LOCATIONS...WITH EVEN LOWER AMOUNTS EXPECTED ACROSS THE NORTHERN FINGER LAKES AND WESTERN MOHAWK VALLEY AS MAX FRONTAL FORCING REMAINS SOUTH. HIGH TEMPS WILL TOP OUT IN LOWER 40S ACROSS THE NORTHERN FINGER LAKES AND LAKE PLAIN...WITH MIDDLE TO UPPER 30S DOMINATE ELSEWHERE. && .SHORT TERM /6 PM THIS EVENING THROUGH SUNDAY NIGHT/... FAIRLY ACTIVE PERIOD CONTINUING TO TAKE SHAPE THROUGH THE UPCOMING WEEKEND AS THE NEXT IN A SERIES OF SFC LOWS LIFTS NORTH ALONG A STALLED FRONT TO OUR WEST BEGINNING TONIGHT. THAT SAID...RA ACROSS THE REGION SHOULD BECOME A LITTLE BIT MORE ORGANIZED INITIALLY THIS EVENING AS SFC LOW LIFTS NORTH FROM THE LWR OHIO VLY INTO THE LWR GREAT LAKES. AS THIS OCCURS...FORCING CONTRIBUTIONS FROM BOTH THE POLAR AND SUBTROPICAL JETS WILL TRANSCEND ACROSS THE REGION WITH ADDITIONAL FORCING ARRIVING FROM CONTINUED ISENTROPIC ASCENT ALONG THE PREVIOUSLY MENTIONED WARM FRONT. THERMAL PROFILES FROM ACROSS THE REGION INDICATE SFC TEMPS WILL REMAIN ABOVE FREEZING AS WARM AIR ADVECTION CONTINUES. THIS SHOULD KEEP ANY PRECIP IN LIQUID FORM. SFC LOW PROGGED TO PASS TO OUR WEST ON SATURDAY WITH INCREASING SOUTHWESTERLY FLOW FINALLY ALLOWING WARM FRONT TO LIFT NORTH THROUGH THE ENTIRE CWA. AS A RESULT...EXPECT A WARMER DAY WITH TEMPS TOPPING OUT IN THE UPPER 40S TO LOWER 50S ACROSS MUCH OF THE AREA. WITH BEST FORCING FOR ASCENT ARRIVING FROM A NORTHERN STREAM SHORTWAVE ACROSS THE UPPER GREAT LAKES...BEST CHANCES FOR ORGANIZED PRECIP WILL LIKELY REMAIN NORTH AND WEST OF OUR AREA. DESPITE THIS HOWEVER...SHORT TERM MODELS INDICATE A DEVELOPING SECONDARY LOW OFF THE NJ COAST THROUGH THE DAY WHICH COMBINED WITH A WEAKER SHORTWAVE IMPULSE PASSING OVERHEAD SHOULD KEEP THE CHC FOR SHWRS ACROSS THE AREA THROUGH THE DAY. MAIN LOW EXPECTED TO PASS TO OUR NORTH OVERNIGHT WHICH WILL SEND A COLD FRONT SOUTH ACROSS THE FCST AREA. MODELS AGREE A QUICK COOL DOWN WILL OCCUR AFTER PASSAGE WITH 850-MB TEMPS QUICKLY FALLING TO -4C ACROSS THE FAR NORTH. HIGHLY SHEARED FLOW COMBINED WITH THE INFLUX OF DRY AIR AND ONLY MARGINAL TEMP DIFFERENCES WILL NEGATE ANY LAKE RESPONSE AND THUS HAVE DRIED THINGS OUT FROM NORTH TO SOUTH OVERNIGHT EARLY SUN. NEXT MORE POTENT WAVE TO LIFT NORTH FROM THE OHIO VLY ON SUN WHICH WILL ONCE AGAIN LIFT THE FRONT BACK NORTH THROUGH BEGINNING SUN NGT. AS SUCH...EXPECT INCREASING CHANCES FOR RAIN ONCE AGAIN SUN AFTERNOON AND EVENING. && .LONG TERM /MONDAY THROUGH THURSDAY/... 430 AM UPDATE... NO CHGS NEEDED TO LONG TERM AT THIS TIME AS FRONT MVS THRU MON EVNG WITH LKLY RAIN SHOWERS. NW FLOW KICKS IN FOLLOWING FROPA TO RESULT IN LK EFFECT PCPN. BOTH 12Z AND NOW 00Z EC INDICATE DVLPNG SFC LOPRES RIDING UP ALONG SFC BNDRY JUST OFF THE EAST COAST BY EARLY WEEK, ALTHO NO OTHER MED RANGE MODELS HV THIS FEATURE. PREV DISCUSSION BLO... MEDIUM RANGE MODELS CONTINUE TO SHOW FAIR AGREEMENT THROUGH THE EXTENDED PERIOD. SUNDAY NIGHT THROUGH MONDAY, SFC LOW PRES WILL TRACK FROM THE OHIO VALLEY NORTHEAST ACROSS LAKE ERIE INTO NEARBY SOUTHERN ONTARIO. WILL CARRY LIKELY POPS BOTH PERIODS WITH RAIN LIKELY SUNDAY NIGHT FOLLOWED BY RAIN SHOWERS ON MONDAY AS TRAILING COLD FRONT CROSSES AREA MONDAY AFTERNOON AND EVENING. THROUGH MONDAY EVENING TEMPS WILL REMAIN WARM ENOUGH FOR JUST LIQUID PRECIP TO FALL. MONDAY NIGHT AS TEMPS LOWER UNDER CAA AND NORTHWEST FLOW, A WEAK LAKE RESPONSE MAY OCCUR INTO TUESDAY. TUESDAY NIGHT THROUGH THURSDAY, LOOKS DRY WITH SFC HIGH PRES STRETCHING FROM THE MID ATLANTIC REGION INTO NEW ENGLAND. TEMPS THROUGH THE PERIOD WILL START WELL ABOVE NORMAL THEN FALL TO SEASONAL LEVELS TUESDAY AND WEDNESDAY BEFORE MODERATING AGAIN ON THURSDAY. && .AVIATION /14Z FRIDAY THROUGH TUESDAY/... 12Z UPDATE... VFR INITIALLY WILL GIVE WAY TO MVFR CIGS LATE THIS MORNING. AS PCPN MOVES FROM SOUTH TO NORTH IT WILL BRING MVFR VSBYS TO TERMINALS AFTER 18Z. LIGHT RAIN WILL CONTINUE THROUGH THE DAY WITH MVFR CONDITIONS EXPECTED. HIGHER TERMINALS WILL LIKELY SEE THESE CIGS DECREASE TO IFR AFTER 05Z AS LOW LEVEL MOISTURE REMAINS ENTRENCHED ACROSS THE AREA. SOUTH WINDS AROUND 5 KTS WILL INCREASE TO NEAR 10KTS THIS AFTERNOON THEN DIMINISH TO LGT/VRB AFTER 06Z. OUTLOOK... SATURDAY...MVFR IN SHRA. SATURDAY NIGHT/SUNDAY MORNING...PRIMARILY VFR. SUNDAY AFTERNOON THROUGH MONDAY EVENING...RESTRICTIONS EXPECTED IN RAIN. TUESDAY...VFR. && .BGM WATCHES/WARNINGS/ADVISORIES... PA...FREEZING RAIN ADVISORY UNTIL 11 AM EST THIS MORNING FOR PAZ040- 048-072. FREEZING RAIN ADVISORY UNTIL 10 AM EST THIS MORNING FOR PAZ038- 039-043-044-047. NY...FREEZING RAIN ADVISORY UNTIL 11 AM EST THIS MORNING FOR NYZ057- 062. FREEZING RAIN ADVISORY UNTIL 11 AM EST THIS MORNING FOR NYZ045- 046-055-056. && $$ SYNOPSIS...CMG NEAR TERM...CMG/RRM SHORT TERM...CMG LONG TERM...PVN/RRM AVIATION...PVN
AREA FORECAST DISCUSSION
NWS BINGHAMTON NY
649 AM EST FRI DEC 7 2012 .SYNOPSIS... AN APPROACHING WARM FRONT WILL LEAD TO SCATTERED SHOWERS ACROSS THE REGION TODAY. THIS WILL MARK THE BEGINNING OF A RATHER UNSETTLED PERIOD WITH SCATTERED SHOWERS POSSIBLE EACH DAY AS SEVERAL DISTURBANCES INTERACT WITH THE STALLED FRONT. TEMPERATURES THROUGH THE WEEKEND WILL REMAIN ABOVE NORMAL AS ANY COLD AIR REMAINS DISPLACED WELL TO OUR WEST. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... 650 AM UPDATE... BASED ON TEMP TRENDS FROM LOCAL MESONET OBSERVATIONS...HAVE ELECTED TO GO WITH AN FREEZING RAIN ADVISORY FOR ALL OF NE PA AND THE CATSKILLS OF EASTERN NY. AS PRECIP CONTINUES TO MOVE IN...CANNOT RULE OUT VERY LIGHT ICE ACCUMULATIONS FOR ELEVATIONS GRATER THAN 1000 FEET. FOR NOW HAVE HELD OFF FOR THE CENTRAL AND EASTERN SOUTHERN TIER AS BULK OF INITIAL BATCH OF RA WILL LIKELY PASS JUST TO THE SOUTH. AFTER THIS...TEMPS SHOULD WARM ABOVE FREEZING HOPEFULLY NEGATING ANY FREEZING RAIN CONCERNS FOR THESE AREAS. NO OTHER SIGNIFICANT CHANGES NEEDED AT THE PRESENT TIME. PREVIOUS NEAR TERM DISCUSSION... MAIN CONCERN IN THE NEAR TERM CONTINUES TO BE APPROACHING FRONTAL WAVE AND ASSOCIATED PRECIP LATER THIS MORNING. LATEST REGIONAL RADAR IMAGES SHOWING LEADING EDGE OF RAIN NOW EAST OF PIT AND WORKING TOWARDS JST IN SW PA. AHEAD OF THIS PRECIP...A SUBSTANTIAL AMOUNT OF DRY AIR REMAINS IN PLACE AS EVIDENCED BY 00Z PIT AND BUF RAOBS. PRECIP IS BEING FORCED LARGELY BY ISENTROPIC ASCENT ALONG THE 285-295 THETA SURFACES AS INCREASING WINDS AT THE 925 AND 850-MB LEVELS ASCEND THE APPROACHING FRONTAL BOUNDARY. WITH THE AMOUNT OF DRY AIR IN PLACE...HAVE ELECTED TO TRIM BACK TIMING OF PRECIP ARRIVAL TIME FROM THE TWIN TIERS AND POINTS SOUTH. IT NOW APPEARS THAT PRECIP WILL NOT MAKE INTO THE CWA BEFORE 12Z AS SUFFICIENT TIME WILL BE REQUIRED TO MOISTEN THE ATMOSPHERIC COLUMN. THE ABOVE SAID...MAIN ATTENTION CONTINUES TO FOCUS ON FZRA POTENTIAL AS INITIAL BATCH OF PRECIP MOVES IN. CLOSE INSPECTION OF BOTH RR AND WRF THETA SURFACES AND MODEL CONDENSATION PRESSURE DEFICITS REVEALS APPROPRIATE SATURATION ALONG THE 285 SFC WILL NOT OCCUR UNTIL 12-13Z AT THE EARLIEST. BY THIS TIME...DIURNAL TEMPS SHOULD BEGIN REBOUNDING AS DAYTIME HEATING COMMENCES WHICH SHOULD ONLY RESULT IN A VERY BRIEF PERIOD WHERE SFC TEMPS MAY BE COLD ENOUGH TO SUPPORT FZRA ALONG THE ELEVATED SURFACES OF THE NORTHERN TIER AND LOWER WYOMING VALLEY REGIONS OF NE PA. BEYOND THIS...RA WILL GRADUALLY OVERSPREAD THE REGION THROUGH THE MORNING AND AFTERNOON HRS. UP NORTH...PRECIP WILL LIKELY HOLD OFF UNTIL EARLY AFTERNOON AFTER WHICH...WEAK SHORTWAVE ENERGY RIDING ALONG THE FRONT SHOULD EVENTUALLY ALLOW PRECIP TO EXTEND AS FAR NORTH AS THE SYR AND RME AREAS. RAINFALL AMOUNTS THROUGH THE DAY WILL LIKELY REMAIN UNDER 2 TENTH OF AN INCH AT MOST LOCATIONS...WITH EVEN LOWER AMOUNTS EXPECTED ACROSS THE NORTHERN FINGER LAKES AND WESTERN MOHAWK VALLEY AS MAX FRONTAL FORCING REMAINS SOUTH. HIGH TEMPS WILL TOP OUT IN LOWER 40S ACROSS THE NORTHERN FINGER LAKES AND LAKE PLAIN...WITH MIDDLE TO UPPER 30S DOMINATE ELSEWHERE. && .SHORT TERM /6 PM THIS EVENING THROUGH SUNDAY NIGHT/... FAIRLY ACTIVE PERIOD CONTINUING TO TAKE SHAPE THROUGH THE UPCOMING WEEKEND AS THE NEXT IN A SERIES OF SFC LOWS LIFTS NORTH ALONG A STALLED FRONT TO OUR WEST BEGINNING TONIGHT. THAT SAID...RA ACROSS THE REGION SHOULD BECOME A LITTLE BIT MORE ORGANIZED INITIALLY THIS EVENING AS SFC LOW LIFTS NORTH FROM THE LWR OHIO VLY INTO THE LWR GREAT LAKES. AS THIS OCCURS...FORCING CONTRIBUTIONS FROM BOTH THE POLAR AND SUBTROPICAL JETS WILL TRANSCEND ACROSS THE REGION WITH ADDITIONAL FORCING ARRIVING FROM CONTINUED ISENTROPIC ASCENT ALONG THE PREVIOUSLY MENTIONED WARM FRONT. THERMAL PROFILES FROM ACROSS THE REGION INDICATE SFC TEMPS WILL REMAIN ABOVE FREEZING AS WARM AIR ADVECTION CONTINUES. THIS SHOULD KEEP ANY PRECIP IN LIQUID FORM. SFC LOW PROGGED TO PASS TO OUR WEST ON SATURDAY WITH INCREASING SOUTHWESTERLY FLOW FINALLY ALLOWING WARM FRONT TO LIFT NORTH THROUGH THE ENTIRE CWA. AS A RESULT...EXPECT A WARMER DAY WITH TEMPS TOPPING OUT IN THE UPPER 40S TO LOWER 50S ACROSS MUCH OF THE AREA. WITH BEST FORCING FOR ASCENT ARRIVING FROM A NORTHERN STREAM SHORTWAVE ACROSS THE UPPER GREAT LAKES...BEST CHANCES FOR ORGANIZED PRECIP WILL LIKELY REMAIN NORTH AND WEST OF OUR AREA. DESPITE THIS HOWEVER...SHORT TERM MODELS INDICATE A DEVELOPING SECONDARY LOW OFF THE NJ COAST THROUGH THE DAY WHICH COMBINED WITH A WEAKER SHORTWAVE IMPULSE PASSING OVERHEAD SHOULD KEEP THE CHC FOR SHWRS ACROSS THE AREA THROUGH THE DAY. MAIN LOW EXPECTED TO PASS TO OUR NORTH OVERNIGHT WHICH WILL SEND A COLD FRONT SOUTH ACROSS THE FCST AREA. MODELS AGREE A QUICK COOL DOWN WILL OCCUR AFTER PASSAGE WITH 850-MB TEMPS QUICKLY FALLING TO -4C ACROSS THE FAR NORTH. HIGHLY SHEARED FLOW COMBINED WITH THE INFLUX OF DRY AIR AND ONLY MARGINAL TEMP DIFFERENCES WILL NEGATE ANY LAKE RESPONSE AND THUS HAVE DRIED THINGS OUT FROM NORTH TO SOUTH OVERNIGHT EARLY SUN. NEXT MORE POTENT WAVE TO LIFT NORTH FROM THE OHIO VLY ON SUN WHICH WILL ONCE AGAIN LIFT THE FRONT BACK NORTH THROUGH BEGINNING SUN NGT. AS SUCH...EXPECT INCREASING CHANCES FOR RAIN ONCE AGAIN SUN AFTERNOON AND EVENING. && .LONG TERM /MONDAY THROUGH THURSDAY/... 430 AM UPDATE... NO CHGS NEEDED TO LONG TERM AT THIS TIME AS FRONT MVS THRU MON EVNG WITH LKLY RAIN SHOWERS. NW FLOW KICKS IN FOLLOWING FROPA TO RESULT IN LK EFFECT PCPN. BOTH 12Z AND NOW 00Z EC INDICATE DVLPNG SFC LOPRES RIDING UP ALONG SFC BNDRY JUST OFF THE EAST COAST BY EARLY WEEK, ALTHO NO OTHER MED RANGE MODELS HV THIS FEATURE. PREV DISCUSSION BLO... MEDIUM RANGE MODELS CONTINUE TO SHOW FAIR AGREEMENT THROUGH THE EXTENDED PERIOD. SUNDAY NIGHT THROUGH MONDAY, SFC LOW PRES WILL TRACK FROM THE OHIO VALLEY NORTHEAST ACROSS LAKE ERIE INTO NEARBY SOUTHERN ONTARIO. WILL CARRY LIKELY POPS BOTH PERIODS WITH RAIN LIKELY SUNDAY NIGHT FOLLOWED BY RAIN SHOWERS ON MONDAY AS TRAILING COLD FRONT CROSSES AREA MONDAY AFTERNOON AND EVENING. THROUGH MONDAY EVENING TEMPS WILL REMAIN WARM ENOUGH FOR JUST LIQUID PRECIP TO FALL. MONDAY NIGHT AS TEMPS LOWER UNDER CAA AND NORTHWEST FLOW, A WEAK LAKE RESPONSE MAY OCCUR INTO TUESDAY. TUESDAY NIGHT THROUGH THURSDAY, LOOKS DRY WITH SFC HIGH PRES STRETCHING FROM THE MID ATLANTIC REGION INTO NEW ENGLAND. TEMPS THROUGH THE PERIOD WILL START WELL ABOVE NORMAL THEN FALL TO SEASONAL LEVELS TUESDAY AND WEDNESDAY BEFORE MODERATING AGAIN ON THURSDAY. && .AVIATION /12Z FRIDAY THROUGH TUESDAY/... 12Z UPDATE... VFR INITIALLY WILL GIVE WAY TO MVFR CIGS LATE THIS MORNING. AS PCPN MOVES FROM SOUTH TO NORTH IT WILL BRING MVFR VSBYS TO TERMINALS AFTER 18Z. LIGHT RAIN WILL CONTINUE THROUGH THE DAY WITH MVFR CONDITIONS EXPECTED. HIGHER TERMINALS WILL LIKELY SEE THESE CIGS DECREASE TO IFR AFTER 05Z AS LOW LEVEL MOISTURE REMAINS ENTRENCHED ACROSS THE AREA. SOUTH WINDS AROUND 5 KTS WILL INCREASE TO NEAR 10KTS THIS AFTERNOON THEN DIMINISH TO LGT/VRB AFTER 06Z. OUTLOOK... SATURDAY...MVFR IN SHRA. SATURDAY NIGHT/SUNDAY MORNING...PRIMARILY VFR. SUNDAY AFTERNOON THROUGH MONDAY EVENING...RESTRICTIONS EXPECTED IN RAIN. TUESDAY...VFR. && .BGM WATCHES/WARNINGS/ADVISORIES... PA...FREEZING RAIN ADVISORY UNTIL 11 AM EST THIS MORNING FOR PAZ040- 048-072. FREEZING RAIN ADVISORY UNTIL 10 AM EST THIS MORNING FOR PAZ038- 039-043-044-047. NY...FREEZING RAIN ADVISORY UNTIL 11 AM EST THIS MORNING FOR NYZ057- 062. && $$ SYNOPSIS...CMG NEAR TERM...CMG SHORT TERM...CMG LONG TERM...PVN/RRM AVIATION...PVN
AREA FORECAST DISCUSSION
NWS BINGHAMTON NY
639 AM EST FRI DEC 7 2012 .SYNOPSIS... AN APPROACHING WARM FRONT WILL LEAD TO SCATTERED SHOWERS ACROSS THE REGION TODAY. THIS WILL MARK THE BEGINNING OF A RATHER UNSETTLED PERIOD WITH SCATTERED SHOWERS POSSIBLE EACH DAY AS SEVERAL DISTURBANCES INTERACT WITH THE STALLED FRONT. TEMPERATURES THROUGH THE WEEKEND WILL REMAIN ABOVE NORMAL AS ANY COLD AIR REMAINS DISPLACED WELL TO OUR WEST. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... MAIN CONCERN IN THE NEAR TERM CONTINUES TO BE APPROACHING FRONTAL WAVE AND ASSOCIATED PRECIP LATER THIS MORNING. LATEST REGIONAL RADAR IMAGES SHOWING LEADING EDGE OF RAIN NOW EAST OF PIT AND WORKING TOWARDS JST IN SW PA. AHEAD OF THIS PRECIP...A SUBSTANTIAL AMOUNT OF DRY AIR REMAINS IN PLACE AS EVIDENCED BY 00Z PIT AND BUF RAOBS. PRECIP IS BEING FORCED LARGELY BY ISENTROPIC ASCENT ALONG THE 285-295 THETA SURFACES AS INCREASING WINDS AT THE 925 AND 850-MB LEVELS ASCEND THE APPROACHING FRONTAL BOUNDARY. WITH THE AMOUNT OF DRY AIR IN PLACE...HAVE ELECTED TO TRIM BACK TIMING OF PRECIP ARRIVAL TIME FROM THE TWIN TIERS AND POINTS SOUTH. IT NOW APPEARS THAT PRECIP WILL NOT MAKE INTO THE CWA BEFORE 12Z AS SUFFICIENT TIME WILL BE REQUIRED TO MOISTEN THE ATMOSPHERIC COLUMN. THE ABOVE SAID...MAIN ATTENTION CONTINUES TO FOCUS ON FZRA POTENTIAL AS INITIAL BATCH OF PRECIP MOVES IN. CLOSE INSPECTION OF BOTH RR AND WRF THETA SURFACES AND MODEL CONDENSATION PRESSURE DEFICITS REVEALS APPROPRIATE SATURATION ALONG THE 285 SFC WILL NOT OCCUR UNTIL 13Z AT THE EARLIEST. BY THIS TIME...DIURNAL TEMPS SHOULD BEGIN REBOUNDING AS DAYTIME HEATING COMMENCES WHICH SHOULD ONLY RESULT IN A VERY BRIEF PERIOD WHERE SFC TEMPS MAY BE COLD ENOUGH TO SUPPORT FZRA ALONG THE ELEVATED SURFACES OF THE NORTHERN TIER AND LOWER WYOMING VALLEY REGIONS OF NE PA. CONSIDERING THAT ANY FZRA WILL BE VERY SHORTLIVED...ALONG WITH THE FACT THAT OVERALL CONFIDENCE REMAINS BELOW 25%...HAVE ELECTED FOR FORGO ANY WINTER WX HEADLINES FOR THE TIME BEING. IF TRENDS SUGGEST A BETTER POTENTIAL FOR FREEZING PRECIP IN THE COMING HRS...A QUICK WSW STATEMENT OR SPS CAN BE ISSUED AS NEEDED. HOWEVER WITH SUCH DRY AIR IN PLACE AHEAD OF THE FRONT AND LATER ARRIVAL TIME...CONFIDENCE IS JUST NOT HIGH ENOUGH TO WARRANT ANY HEADLINES ATTM. BEYOND THIS...RA WILL GRADUALLY OVERSPREAD THE REGION THROUGH THE MORNING AND AFTERNOON HRS. UP NORTH...PRECIP WILL LIKELY HOLD OFF UNTIL EARLY AFTERNOON AFTER WHICH...WEAK SHORTWAVE ENERGY RIDING ALONG THE FRONT SHOULD EVENTUALLY ALLOW PRECIP TO EXTEND AS FAR NORTH AS THE SYR AND RME AREAS. RAINFALL AMOUNTS THROUGH THE DAY WILL LIKELY REMAIN UNDER 2 TENTH OF AN INCH AT MOST LOCATIONS...WITH EVEN LOWER AMOUNTS EXPECTED ACROSS THE NORTHERN FINGER LAKES AND WESTERN MOHAWK VALLEY AS MAX FRONTAL FORCING REMAINS SOUTH. HIGH TEMPS WILL TOP OUT IN LOWER 40S ACROSS THE NORTHERN FINGER LAKES AND LAKE PLAIN...WITH MIDDLE TO UPPER 30S DOMINATE ELSEWHERE. && .SHORT TERM /6 PM THIS EVENING THROUGH SUNDAY NIGHT/... FAIRLY ACTIVE PERIOD CONTINUING TO TAKE SHAPE THROUGH THE UPCOMING WEEKEND AS THE NEXT IN A SERIES OF SFC LOWS LIFTS NORTH ALONG A STALLED FRONT TO OUR WEST BEGINNING TONIGHT. THAT SAID...RA ACROSS THE REGION SHOULD BECOME A LITTLE BIT MORE ORGANIZED INITIALLY THIS EVENING AS SFC LOW LIFTS NORTH FROM THE LWR OHIO VLY INTO THE LWR GREAT LAKES. AS THIS OCCURS...FORCING CONTRIBUTIONS FROM BOTH THE POLAR AND SUBTROPICAL JETS WILL TRANSCEND ACROSS THE REGION WITH ADDITIONAL FORCING ARRIVING FROM CONTINUED ISENTROPIC ASCENT ALONG THE PREVIOUSLY MENTIONED WARM FRONT. THERMAL PROFILES FROM ACROSS THE REGION INDICATE SFC TEMPS WILL REMAIN ABOVE FREEZING AS WARM AIR ADVECTION CONTINUES. THIS SHOULD KEEP ANY PRECIP IN LIQUID FORM. SFC LOW PROGGED TO PASS TO OUR WEST ON SATURDAY WITH INCREASING SOUTHWESTERLY FLOW FINALLY ALLOWING WARM FRONT TO LIFT NORTH THROUGH THE ENTIRE CWA. AS A RESULT...EXPECT A WARMER DAY WITH TEMPS TOPPING OUT IN THE UPPER 40S TO LOWER 50S ACROSS MUCH OF THE AREA. WITH BEST FORCING FOR ASCENT ARRIVING FROM A NORTHERN STREAM SHORTWAVE ACROSS THE UPPER GREAT LAKES...BEST CHANCES FOR ORGANIZED PRECIP WILL LIKELY REMAIN NORTH AND WEST OF OUR AREA. DESPITE THIS HOWEVER...SHORT TERM MODELS INDICATE A DEVELOPING SECONDARY LOW OFF THE NJ COAST THROUGH THE DAY WHICH COMBINED WITH A WEAKER SHORTWAVE IMPULSE PASSING OVERHEAD SHOULD KEEP THE CHC FOR SHWRS ACROSS THE AREA THROUGH THE DAY. MAIN LOW EXPECTED TO PASS TO OUR NORTH OVERNIGHT WHICH WILL SEND A COLD FRONT SOUTH ACROSS THE FCST AREA. MODELS AGREE A QUICK COOL DOWN WILL OCCUR AFTER PASSAGE WITH 850-MB TEMPS QUICKLY FALLING TO -4C ACROSS THE FAR NORTH. HIGHLY SHEARED FLOW COMBINED WITH THE INFLUX OF DRY AIR AND ONLY MARGINAL TEMP DIFFERENCES WILL NEGATE ANY LAKE RESPONSE AND THUS HAVE DRIED THINGS OUT FROM NORTH TO SOUTH OVERNIGHT EARLY SUN. NEXT MORE POTENT WAVE TO LIFT NORTH FROM THE OHIO VLY ON SUN WHICH WILL ONCE AGAIN LIFT THE FRONT BACK NORTH THROUGH BEGINNING SUN NGT. AS SUCH...EXPECT INCREASING CHANCES FOR RAIN ONCE AGAIN SUN AFTERNOON AND EVENING. && .LONG TERM /MONDAY THROUGH THURSDAY/... 430 AM UPDATE... NO CHGS NEEDED TO LONG TERM AT THIS TIME AS FRONT MVS THRU MON EVNG WITH LKLY RAIN SHOWERS. NW FLOW KICKS IN FOLLOWING FROPA TO RESULT IN LK EFFECT PCPN. BOTH 12Z AND NOW 00Z EC INDICATE DVLPNG SFC LOPRES RIDING UP ALONG SFC BNDRY JUST OFF THE EAST COAST BY EARLY WEEK, ALTHO NO OTHER MED RANGE MODELS HV THIS FEATURE. PREV DISCUSSION BLO... MEDIUM RANGE MODELS CONTINUE TO SHOW FAIR AGREEMENT THROUGH THE EXTENDED PERIOD. SUNDAY NIGHT THROUGH MONDAY, SFC LOW PRES WILL TRACK FROM THE OHIO VALLEY NORTHEAST ACROSS LAKE ERIE INTO NEARBY SOUTHERN ONTARIO. WILL CARRY LIKELY POPS BOTH PERIODS WITH RAIN LIKELY SUNDAY NIGHT FOLLOWED BY RAIN SHOWERS ON MONDAY AS TRAILING COLD FRONT CROSSES AREA MONDAY AFTERNOON AND EVENING. THROUGH MONDAY EVENING TEMPS WILL REMAIN WARM ENOUGH FOR JUST LIQUID PRECIP TO FALL. MONDAY NIGHT AS TEMPS LOWER UNDER CAA AND NORTHWEST FLOW, A WEAK LAKE RESPONSE MAY OCCUR INTO TUESDAY. TUESDAY NIGHT THROUGH THURSDAY, LOOKS DRY WITH SFC HIGH PRES STRETCHING FROM THE MID ATLANTIC REGION INTO NEW ENGLAND. TEMPS THROUGH THE PERIOD WILL START WELL ABOVE NORMAL THEN FALL TO SEASONAL LEVELS TUESDAY AND WEDNESDAY BEFORE MODERATING AGAIN ON THURSDAY. && .AVIATION /11Z FRIDAY THROUGH TUESDAY/... 12Z UPDATE... VFR INITIALLY WILL GIVE WAY TO MVFR CIGS LATE THIS MORNING. AS PCPN MOVES FROM SOUTH TO NORTH IT WILL BRING MVFR VSBYS TO TERMINALS AFTER 18Z. LIGHT RAIN WILL CONTINUE THROUGH THE DAY WITH MVFR CONDITIONS EXPECTED. HIGHER TERMINALS WILL LIKELY SEE THESE CIGS DECREASE TO IFR AFTER 05Z AS LOW LEVEL MOISTURE REMAINS ENTRENCHED ACROSS THE AREA. SOUTH WINDS AROUND 5 KTS WILL INCREASE TO NEAR 10KTS THIS AFTERNOON THEN DIMINISH TO LGT/VRB AFTER 06Z. OUTLOOK... SATURDAY...MVFR IN SHRA. SATURDAY NIGHT/SUNDAY MORNING...PRIMARILY VFR. SUNDAY AFTERNOON THROUGH MONDAY EVENING...RESTRICTIONS EXPECTED IN RAIN. TUESDAY...VFR. && .BGM WATCHES/WARNINGS/ADVISORIES... PA...NONE. NY...NONE. && $$ SYNOPSIS...CMG NEAR TERM...CMG SHORT TERM...CMG LONG TERM...PVN/RRM AVIATION...PVN
AREA FORECAST DISCUSSION
NWS BINGHAMTON NY
444 AM EST FRI DEC 7 2012 .SYNOPSIS... AN APPROACHING WARM FRONT WILL LEAD TO SCATTERED SHOWERS ACROSS THE REGION TODAY. THIS WILL MARK THE BEGINNING OF A RATHER UNSETTLED PERIOD WITH SCATTERED SHOWERS POSSIBLE EACH DAY AS SEVERAL DISTURBANCES INTERACT WITH THE STALLED FRONT. TEMPERATURES THROUGH THE WEEKEND WILL REMAIN ABOVE NORMAL AS ANY COLD AIR REMAINS DISPLACED WELL TO OUR WEST. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... MAIN CONCERN IN THE NEAR TERM CONTINUES TO BE APPROACHING FRONTAL WAVE AND ASSOCIATED PRECIP LATER THIS MORNING. LATEST REGIONAL RADAR IMAGES SHOWING LEADING EDGE OF RAIN NOW EAST OF PIT AND WORKING TOWARDS JST IN SW PA. AHEAD OF THIS PRECIP...A SUBSTANTIAL AMOUNT OF DRY AIR REMAINS IN PLACE AS EVIDENCED BY 00Z PIT AND BUF RAOBS. PRECIP IS BEING FORCED LARGELY BY ISENTROPIC ASCENT ALONG THE 285-295 THETA SURFACES AS INCREASING WINDS AT THE 925 AND 850-MB LEVELS ASCEND THE APPROACHING FRONTAL BOUNDARY. WITH THE AMOUNT OF DRY AIR IN PLACE...HAVE ELECTED TO TRIM BACK TIMING OF PRECIP ARRIVAL TIME FROM THE TWIN TIERS AND POINTS SOUTH. IT NOW APPEARS THAT PRECIP WILL NOT MAKE INTO THE CWA BEFORE 12Z AS SUFFICIENT TIME WILL BE REQUIRED TO MOISTEN THE ATMOSPHERIC COLUMN. THE ABOVE SAID...MAIN ATTENTION CONTINUES TO FOCUS ON FZRA POTENTIAL AS INITIAL BATCH OF PRECIP MOVES IN. CLOSE INSPECTION OF BOTH RR AND WRF THETA SURFACES AND MODEL CONDENSATION PRESSURE DEFICITS REVEALS APPROPRIATE SATURATION ALONG THE 285 SFC WILL NOT OCCUR UNTIL 13Z AT THE EARLIEST. BY THIS TIME...DIURNAL TEMPS SHOULD BEGIN REBOUNDING AS DAYTIME HEATING COMMENCES WHICH SHOULD ONLY RESULT IN A VERY BRIEF PERIOD WHERE SFC TEMPS MAY BE COLD ENOUGH TO SUPPORT FZRA ALONG THE ELEVATED SURFACES OF THE NORTHERN TIER AND LOWER WYOMING VALLEY REGIONS OF NE PA. CONSIDERING THAT ANY FZRA WILL BE VERY SHORTLIVED...ALONG WITH THE FACT THAT OVERALL CONFIDENCE REMAINS BELOW 25%...HAVE ELECTED FOR FORGO ANY WINTER WX HEADLINES FOR THE TIME BEING. IF TRENDS SUGGEST A BETTER POTENTIAL FOR FREEZING PRECIP IN THE COMING HRS...A QUICK WSW STATEMENT OR SPS CAN BE ISSUED AS NEEDED. HOWEVER WITH SUCH DRY AIR IN PLACE AHEAD OF THE FRONT AND LATER ARRIVAL TIME...CONFIDENCE IS JUST NOT HIGH ENOUGH TO WARRANT ANY HEADLINES ATTM. BEYOND THIS...RA WILL GRADUALLY OVERSPREAD THE REGION THROUGH THE MORNING AND AFTERNOON HRS. UP NORTH...PRECIP WILL LIKELY HOLD OFF UNTIL EARLY AFTERNOON AFTER WHICH...WEAK SHORTWAVE ENERGY RIDING ALONG THE FRONT SHOULD EVENTUALLY ALLOW PRECIP TO EXTEND AS FAR NORTH AS THE SYR AND RME AREAS. RAINFALL AMOUNTS THROUGH THE DAY WILL LIKELY REMAIN UNDER 2 TENTH OF AN INCH AT MOST LOCATIONS...WITH EVEN LOWER AMOUNTS EXPECTED ACROSS THE NORTHERN FINGER LAKES AND WESTERN MOHAWK VALLEY AS MAX FRONTAL FORCING REMAINS SOUTH. HIGH TEMPS WILL TOP OUT IN LOWER 40S ACROSS THE NORTHERN FINGER LAKES AND LAKE PLAIN...WITH MIDDLE TO UPPER 30S DOMINATE ELSEWHERE. && .SHORT TERM /6 PM THIS EVENING THROUGH SUNDAY NIGHT/... FAIRLY ACTIVE PERIOD CONTINUING TO TAKE SHAPE THROUGH THE UPCOMING WEEKEND AS THE NEXT IN A SERIES OF SFC LOWS LIFTS NORTH ALONG A STALLED FRONT TO OUR WEST BEGINNING TONIGHT. THAT SAID...RA ACROSS THE REGION SHOULD BECOME A LITTLE BIT MORE ORGANIZED INITIALLY THIS EVENING AS SFC LOW LIFTS NORTH FROM THE LWR OHIO VLY INTO THE LWR GREAT LAKES. AS THIS OCCURS...FORCING CONTRIBUTIONS FROM BOTH THE POLAR AND SUBTROPICAL JETS WILL TRANSCEND ACROSS THE REGION WITH ADDITIONAL FORCING ARRIVING FROM CONTINUED ISENTROPIC ASCENT ALONG THE PREVIOUSLY MENTIONED WARM FRONT. THERMAL PROFILES FROM ACROSS THE REGION INDICATE SFC TEMPS WILL REMAIN ABOVE FREEZING AS WARM AIR ADVECTION CONTINUES. THIS SHOULD KEEP ANY PRECIP IN LIQUID FORM. SFC LOW PROGGED TO PASS TO OUR WEST ON SATURDAY WITH INCREASING SOUTHWESTERLY FLOW FINALLY ALLOWING WARM FRONT TO LIFT NORTH THROUGH THE ENTIRE CWA. AS A RESULT...EXPECT A WARMER DAY WITH TEMPS TOPPING OUT IN THE UPPER 40S TO LOWER 50S ACROSS MUCH OF THE AREA. WITH BEST FORCING FOR ASCENT ARRIVING FROM A NORTHERN STREAM SHORTWAVE ACROSS THE UPPER GREAT LAKES...BEST CHANCES FOR ORGANIZED PRECIP WILL LIKELY REMAIN NORTH AND WEST OF OUR AREA. DESPITE THIS HOWEVER...SHORT TERM MODELS INDICATE A DEVELOPING SECONDARY LOW OFF THE NJ COAST THROUGH THE DAY WHICH COMBINED WITH A WEAKER SHORTWAVE IMPULSE PASSING OVERHEAD SHOULD KEEP THE CHC FOR SHWRS ACROSS THE AREA THROUGH THE DAY. MAIN LOW EXPECTED TO PASS TO OUR NORTH OVERNIGHT WHICH WILL SEND A COLD FRONT SOUTH ACROSS THE FCST AREA. MODELS AGREE A QUICK COOL DOWN WILL OCCUR AFTER PASSAGE WITH 850-MB TEMPS QUICKLY FALLING TO -4C ACROSS THE FAR NORTH. HIGHLY SHEARED FLOW COMBINED WITH THE INFLUX OF DRY AIR AND ONLY MARGINAL TEMP DIFFERENCES WILL NEGATE ANY LAKE RESPONSE AND THUS HAVE DRIED THINGS OUT FROM NORTH TO SOUTH OVERNIGHT EARLY SUN. NEXT MORE POTENT WAVE TO LIFT NORTH FROM THE OHIO VLY ON SUN WHICH WILL ONCE AGAIN LIFT THE FRONT BACK NORTH THROUGH BEGINNING SUN NGT. AS SUCH...EXPECT INCREASING CHANCES FOR RAIN ONCE AGAIN SUN AFTERNOON AND EVENING. && .LONG TERM /MONDAY THROUGH THURSDAY/... 430 AM UPDATE... NO CHGS NEEDED TO LONG TERM AT THIS TIME AS FRONT MVS THRU MON EVNG WITH LKLY RAIN SHOWERS. NW FLOW KICKS IN FOLLOWING FROPA TO RESULT IN LK EFFECT PCPN. BOTH 12Z AND NOW 00Z EC INDICATE DVLPNG SFC LOPRES RIDING UP ALONG SFC BNDRY JUST OFF THE EAST COAST BY EARLY WEEK, ALTHO NO OTHER MED RANGE MODELS HV THIS FEATURE. PREV DISCUSSION BLO... MEDIUM RANGE MODELS CONTINUE TO SHOW FAIR AGREEMENT THROUGH THE EXTENDED PERIOD. SUNDAY NIGHT THROUGH MONDAY, SFC LOW PRES WILL TRACK FROM THE OHIO VALLEY NORTHEAST ACROSS LAKE ERIE INTO NEARBY SOUTHERN ONTARIO. WILL CARRY LIKELY POPS BOTH PERIODS WITH RAIN LIKELY SUNDAY NIGHT FOLLOWED BY RAIN SHOWERS ON MONDAY AS TRAILING COLD FRONT CROSSES AREA MONDAY AFTERNOON AND EVENING. THROUGH MONDAY EVENING TEMPS WILL REMAIN WARM ENOUGH FOR JUST LIQUID PRECIP TO FALL. MONDAY NIGHT AS TEMPS LOWER UNDER CAA AND NORTHWEST FLOW, A WEAK LAKE RESPONSE MAY OCCUR INTO TUESDAY. TUESDAY NIGHT THROUGH THURSDAY, LOOKS DRY WITH SFC HIGH PRES STRETCHING FROM THE MID ATLANTIC REGION INTO NEW ENGLAND. TEMPS THROUGH THE PERIOD WILL START WELL ABOVE NORMAL THEN FALL TO SEASONAL LEVELS TUESDAY AND WEDNESDAY BEFORE MODERATING AGAIN ON THURSDAY. && .AVIATION /10Z FRIDAY THROUGH TUESDAY/... VFR EXPECTED THROUGH LATE MORNING/EARLY AFTERNOON BEFORE RAIN AND LOW CLOUDS BEGIN TO APPROACH FROM THE SOUTHWEST. LIGHT RAIN WILL MOVE INTO PA TERMINALS BY 15Z THEN NORTH INTO KELM BY 16Z, KBGM BY 17Z, AND KITH BY 18Z. SIGNIFICANT DRY AIR WILL BE IN PLACE ACROSS NORTHERN SITES WHERE RAIN WILL NOT MOVE IN UNTIL AFTER 00Z. BY THE TIME THE RAIN STARTS, SURFACE TEMPERATURES WILL LIKELY RISE ABOVE FREEZING TO PREVENT FREEZING RAIN AT AREA TERMINALS TODAY. MVFR CIGS WILL SPREAD INTO HIGHER ELEVATION TERMINALS (KBGM AND KITH) AFTER 18Z WITH REMAINING TERMINALS DELAYED UNTIL AFTER 20Z. SOUTHEAST WIND WILL SLOWLY COME AROUND TO A MORE SOUTHERLY DIRECTION THIS AFTERNOON AROUND 10KTS. OUTLOOK... SATURDAY...MVFR IN SHRA. SATURDAY NIGHT/SUNDAY MORNING...PRIMARILY VFR. SUNDAY AFTERNOON THROUGH MONDAY EVENING...RESTRICTIONS EXPECTED IN RAIN. TUESDAY...VFR. && .BGM WATCHES/WARNINGS/ADVISORIES... PA...NONE. NY...NONE. && $$ SYNOPSIS...CMG NEAR TERM...CMG SHORT TERM...CMG LONG TERM...PVN/RRM AVIATION...PVN
AREA FORECAST DISCUSSION
NWS BINGHAMTON NY
421 AM EST FRI DEC 7 2012 .SYNOPSIS... AN APPROACHING WARM FRONT WILL LEAD TO SCATTERED SHOWERS ACROSS THE REGION TODAY. THIS WILL MARK THE BEGINNING OF A RATHER UNSETTLED PERIOD WITH SCATTERED SHOWERS POSSIBLE EACH DAY AS SEVERAL DISTURBANCES INTERACT WITH THE STALLED FRONT. TEMPERATURES THROUGH THE WEEKEND WILL REMAIN ABOVE NORMAL AS ANY COLD AIR REMAINS DISPLACED WELL TO OUR WEST. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... MAIN CONCERN IN THE NEAR TERM CONTINUES TO BE APPROACHING FRONTAL WAVE AND ASSOCIATED PRECIP LATER THIS MORNING. LATEST REGIONAL RADAR IMAGES SHOWING LEADING EDGE OF RAIN NOW EAST OF PIT AND WORKING TOWARDS JST IN SW PA. AHEAD OF THIS PRECIP...A SUBSTANTIAL AMOUNT OF DRY AIR REMAINS IN PLACE AS EVIDENCED BY 00Z PIT AND BUF RAOBS. PRECIP IS BEING FORCED LARGELY BY ISENTROPIC ASCENT ALONG THE 285-295 THETA SURFACES AS INCREASING WINDS AT THE 925 AND 850-MB LEVELS ASCEND THE APPROACHING FRONTAL BOUNDARY. WITH THE AMOUNT OF DRY AIR IN PLACE...HAVE ELECTED TO TRIM BACK TIMING OF PRECIP ARRIVAL TIME FROM THE TWIN TIERS AND POINTS SOUTH. IT NOW APPEARS THAT PRECIP WILL NOT MAKE INTO THE CWA BEFORE 12Z AS SUFFICIENT TIME WILL BE REQUIRED TO MOISTEN THE ATMOSPHERIC COLUMN. THE ABOVE SAID...MAIN ATTENTION CONTINUES TO FOCUS ON FZRA POTENTIAL AS INITIAL BATCH OF PRECIP MOVES IN. CLOSE INSPECTION OF BOTH RR AND WRF THETA SURFACES AND MODEL CONDENSATION PRESSURE DEFICITS REVEALS APPROPRIATE SATURATION ALONG THE 285 SFC WILL NOT OCCUR UNTIL 13Z AT THE EARLIEST. BY THIS TIME...DIURNAL TEMPS SHOULD BEGIN REBOUNDING AS DAYTIME HEATING COMMENCES WHICH SHOULD ONLY RESULT IN A VERY BRIEF PERIOD WHERE SFC TEMPS MAY BE COLD ENOUGH TO SUPPORT FZRA ALONG THE ELEVATED SURFACES OF THE NORTHERN TIER AND LOWER WYOMING VALLEY REGIONS OF NE PA. CONSIDERING THAT ANY FZRA WILL BE VERY SHORTLIVED...ALONG WITH THE FACT THAT OVERALL CONFIDENCE REMAINS BELOW 25%...HAVE ELECTED FOR FORGO ANY WINTER WX HEADLINES FOR THE TIME BEING. IF TRENDS SUGGEST A BETTER POTENTIAL FOR FREEZING PRECIP IN THE COMING HRS...A QUICK WSW STATEMENT OR SPS CAN BE ISSUED AS NEEDED. HOWEVER WITH SUCH DRY AIR IN PLACE AHEAD OF THE FRONT AND LATER ARRIVAL TIME...CONFIDENCE IS JUST NOT HIGH ENOUGH TO WARRANT ANY HEADLINES ATTM. BEYOND THIS...RA WILL GRADUALLY OVERSPREAD THE REGION THROUGH THE MORNING AND AFTERNOON HRS. UP NORTH...PRECIP WILL LIKELY HOLD OFF UNTIL EARLY AFTERNOON AFTER WHICH...WEAK SHORTWAVE ENERGY RIDING ALONG THE FRONT SHOULD EVENTUALLY ALLOW PRECIP TO EXTEND AS FAR NORTH AS THE SYR AND RME AREAS. RAINFALL AMOUNTS THROUGH THE DAY WILL LIKELY REMAIN UNDER 2 TENTH OF AN INCH AT MOST LOCATIONS...WITH EVEN LOWER AMOUNTS EXPECTED ACROSS THE NORTHERN FINGER LAKES AND WESTERN MOHAWK VALLEY AS MAX FRONTAL FORCING REMAINS SOUTH. HIGH TEMPS WILL TOP OUT IN LOWER 40S ACROSS THE NORTHERN FINGER LAKES AND LAKE PLAIN...WITH MIDDLE TO UPPER 30S DOMINATE ELSEWHERE. && .SHORT TERM /6 PM THIS EVENING THROUGH SUNDAY NIGHT/... FAIRLY ACTIVE PERIOD CONTINUING TO TAKE SHAPE THROUGH THE UPCOMING WEEKEND AS THE NEXT IN A SERIES OF SFC LOWS LIFTS NORTH ALONG A STALLED FRONT TO OUR WEST BEGINNING TONIGHT. THAT SAID...RA ACROSS THE REGION SHOULD BECOME A LITTLE BIT MORE ORGANIZED INITIALLY THIS EVENING AS SFC LOW LIFTS NORTH FROM THE LWR OHIO VLY INTO THE LWR GREAT LAKES. AS THIS OCCURS...FORCING CONTRIBUTIONS FROM BOTH THE POLAR AND SUBTROPICAL JETS WILL TRANSCEND ACROSS THE REGION WITH ADDITIONAL FORCING ARRIVING FROM CONTINUED ISENTROPIC ASCENT ALONG THE PREVIOUSLY MENTIONED WARM FRONT. THERMAL PROFILES FROM ACROSS THE REGION INDICATE SFC TEMPS WILL REMAIN ABOVE FREEZING AS WARM AIR ADVECTION CONTINUES. THIS SHOULD KEEP ANY PRECIP IN LIQUID FORM. SFC LOW PROGGED TO PASS TO OUR WEST ON SATURDAY WITH INCREASING SOUTHWESTERLY FLOW FINALLY ALLOWING WARM FRONT TO LIFT NORTH THROUGH THE ENTIRE CWA. AS A RESULT...EXPECT A WARMER DAY WITH TEMPS TOPPING OUT IN THE UPPER 40S TO LOWER 50S ACROSS MUCH OF THE AREA. WITH BEST FORCING FOR ASCENT ARRIVING FROM A NORTHERN STREAM SHORTWAVE ACROSS THE UPPER GREAT LAKES...BEST CHANCES FOR ORGANIZED PRECIP WILL LIKELY REMAIN NORTH AND WEST OF OUR AREA. DESPITE THIS HOWEVER...SHORT TERM MODELS INDICATE A DEVELOPING SECONDARY LOW OFF THE NJ COAST THROUGH THE DAY WHICH COMBINED WITH A WEAKER SHORTWAVE IMPULSE PASSING OVERHEAD SHOULD KEEP THE CHC FOR SHWRS ACROSS THE AREA THROUGH THE DAY. MAIN LOW EXPECTED TO PASS TO OUR NORTH OVERNIGHT WHICH WILL SEND A COLD FRONT SOUTH ACROSS THE FCST AREA. MODELS AGREE A QUICK COOL DOWN WILL OCCUR AFTER PASSAGE WITH 850-MB TEMPS QUICKLY FALLING TO -4C ACROSS THE FAR NORTH. HIGHLY SHEARED FLOW COMBINED WITH THE INFLUX OF DRY AIR AND ONLY MARGINAL TEMP DIFFERENCES WILL NEGATE ANY LAKE RESPONSE AND THUS HAVE DRIED THINGS OUT FROM NORTH TO SOUTH OVERNIGHT EARLY SUN. NEXT MORE POTENT WAVE TO LIFT NORTH FROM THE OHIO VLY ON SUN WHICH WILL ONCE AGAIN LIFT THE FRONT BACK NORTH THROUGH BEGINNING SUN NGT. AS SUCH...EXPECT INCREASING CHANCES FOR RAIN ONCE AGAIN SUN AFTERNOON AND EVENING. && .LONG TERM /MONDAY THROUGH THURSDAY/... MEDIUM RANGE MODELS CONTINUE TO SHOW FAIR AGREEMENT THROUGH THE EXTENDED PERIOD. SUNDAY NIGHT THROUGH MONDAY, SFC LOW PRES WILL TRACK FROM THE OHIO VALLEY NORTHEAST ACROSS LAKE ERIE INTO NEARBY SOUTHERN ONTARIO. WILL CARRY LIKELY POPS BOTH PERIODS WITH RAIN LIKELY SUNDAY NIGHT FOLLOWED BY RAIN SHOWERS ON MONDAY AS TRAILING COLD FRONT CROSSES AREA MONDAY AFTERNOON AND EVENING. THROUGH MONDAY EVENING TEMPS WILL REMAIN WARM ENOUGH FOR JUST LIQUID PRECIP TO FALL. MONDAY NIGHT AS TEMPS LOWER UNDER CAA AND NORTHWEST FLOW, A WEAK LAKE RESPONSE MAY OCCUR INTO TUESDAY. TUESDAY NIGHT THROUGH THURSDAY, LOOKS DRY WITH SFC HIGH PRES STRETCHING FROM THE MID ATLANTIC REGION INTO NEW ENGLAND. TEMPS THROUGH THE PERIOD WILL START WELL ABOVE NORMAL THEN FALL TO SEASONAL LEVELS TUESDAY AND WEDNESDAY BEFORE MODERATING AGAIN ON THURSDAY. && .AVIATION /08Z FRIDAY THROUGH TUESDAY/... VFR EXPECTED THROUGH LATE MORNING/EARLY AFTERNOON BEFORE RAIN AND LOW CLOUDS BEGIN TO APPROACH FROM THE SOUTHWEST. LIGHT RAIN WILL MOVE INTO PA TERMINALS BY 15Z THEN NORTH INTO KELM BY 16Z, KBGM BY 17Z, AND KITH BY 18Z. SIGNIFICANT DRY AIR WILL BE IN PLACE ACROSS NORTHERN SITES WHERE RAIN WILL NOT MOVE IN UNTIL AFTER 00Z. BY THE TIME THE RAIN STARTS, SURFACE TEMPERATURES WILL LIKELY RISE ABOVE FREEZING TO PREVENT FREEZING RAIN AT AREA TERMINALS TODAY. MVFR CIGS WILL SPREAD INTO HIGHER ELEVATION TERMINALS (KBGM AND KITH) AFTER 18Z WITH REMAINING TERMINALS DELAYED UNTIL AFTER 20Z. SOUTHEAST WIND WILL SLOWLY COME AROUND TO A MORE SOUTHERLY DIRECTION THIS AFTERNOON AROUND 10KTS. OUTLOOK... SATURDAY...MVFR IN SHRA. SATURDAY NIGHT/SUNDAY MORNING...PRIMARILY VFR. SUNDAY AFTERNOON THROUGH MONDAY EVENING...RESTRICTIONS EXPECTED IN RAIN. TUESDAY...VFR. && .BGM WATCHES/WARNINGS/ADVISORIES... PA...NONE. NY...NONE. && $$ SYNOPSIS...CMG NEAR TERM...CMG SHORT TERM...CMG LONG TERM...RRM AVIATION...PVN
AREA FORECAST DISCUSSION
NWS RALEIGH NC
920 PM EST SAT DEC 8 2012 .SYNOPSIS... HIGH PRESSURE OVER THE SOUTHEAST WILL MOVE OFFSHORE SUNDAY. A WARM MOIST SOUTHERLY FLOW AHEAD OF AN APPROACHING COLD FRONT WILL RESULT IN MILD TEMPERATURES THROUGH MONDAY. THE COLD FRONT WILL CROSS THE REGION ON TUESDAY. && .NEAR TERM /TONIGHT THROUGH SUNDAY NIGHT/... AS OF 920 PM SATURDAY... THE MAIN UPDATES TO THE FORECAST THIS EVENING WILL BE TO ADDRESS CLOUD COVER AND RAPIDLY FALLING TEMPS. MID CLOUDS UPSTREAM EARLIER THIS EVENING WERE MORE ROBUST AND EVENING PRODUCING SOME VERY LIGHT PRECIP OVER SOUTHWESTERN NC...BUT HAVE SINCE DECREASED IN COVERAGE AS THEY DRIFT SOUTHWEST TO NORTHEAST ACROSS THE AREA. IN AREAS WHERE SKIES HAVE BEEN MOSTLY CLEAR...PARTICULARLY OVER THE EASTERN HALF OF THE CWA...TEMPS HAVE QUICKLY FALLEN INTO THE UPPER 40S AND LOWER 50S. THE LATEST RAP CONTINUES TO INDICATE MOISTURE UPSTREAM INTO THE AREA WITH A PERIOD OF ISENTROPIC LIFT SUFFICIENT FOR SCATTERED SHOWERS...MAINLY AROUND THE WESTERN PIEDMONT. DUE TO THE EXPECTED INCREASE IN MID LEVEL CLOUD COVER...IN THE 4000-6000 FT RANGE BASED ON UPSTREAM OBS AND FORECAST SOUNDINGS...THERE IS STILL SOME UNCERTAINTY REGARDING THE COVERAGE OF FOG/STRATUS. WHERE SKIES ARE CLEAR...VISIBILITIES HAVE FALLEN INTO THE 3 TO 6 MILE RANGE IN SOME SPOTS...BUT NO FURTHER. WILL CONTINUE TO MONITOR THESE TRENDS TO SEE IF A DENSE FOG ADVISORY IS NEED LATER TONIGHT....BUT CURRENT THINKING IS THAT IT MAY BE MORE LIKELY OVER EASTERN AREAS. WITH TEMPS APPROACHING FORECAST MINS IN SOME OUTLYING AREAS...ALSO IN RESPONSE TO THE CLEAR SKIES...WILL LOWER MIN TEMPS A COUPLE DEGREES. HOWEVER...IF CLOUDS MOVE IN AS EXPECTED...TEMPS SHOULD BEGIN TO LEVEL OUT AND REMAIN IN THE UPPER 40S AND LOWER 50S. -BLS AFTER THE MORNING LOW CLOUDS/FOG LIFT AND DISPERSE AND ISOLATED SHOWER ACTIVITY EXITS THE AREA...A MIX OF SUN AND CLOUDS WILL SUPPORT DAYTIME HIGHS IN THE MID TO UPPER 60S NORTH TO LOWER/MID 70S SOUTH. THE UPSTREAM TROUGH WILL BEGIN TO DIG INTO THE SOUTHERN PLAINS SUNDAY NIGHT WITH ATTENDANT SFC COLD FRONT ADVANCING EAST INTO THE TN VALLEY. RISING PWATS FROM STRENGTHENING WARM MOIST AIR ADVECTION...INCREASING RIGHT-ENTRANCE REGION DYNAMICS...THE POTENTIAL FOR WEAK INSTABILITY ALOFT ALONG WITH THE PROSPECTS OF SOME WEAK SHORTWAVE DISTURBANCES TO MOVE THROUGH THE AREA IN THE SWLY FLOW ALOFT WILL SUPPORT ISOLATED SHOWERS...MAINLY IN THE WEST LATE SUNDAY NIGHT. && .SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/... AS OF 300 PM SATURDAY... A COLD FRONT WILL APPROACH AND CROSS THE REGION OVERNIGHT MONDAY INTO TUESDAY...ALTHOUGH THERE ARE STILL SOME TIMING DIFFERENCES AMONG THE MODELS...BUT THERE CONTINUES TO SOME TREND OF A SLOWER PASSAGE. AHEAD OF THE FRONT...INCREASING SOUTHWESTERLY WINDS WILL USHER IN MOISTURE AND EVEN MORE WARMTH DURING THE DAY ON MONDAY. TEMPS ARE EXPECTED TO RANGE FROM THE LOW 70S ACROSS THE NORTHWEST TO THE MID 70S FURTHER SOUTH AND EAST. THERE COULD EVEN BE SOME UPPER 70S ACROSS THE SOUTHEAST...ALTHOUGH THE AMOUNT OF CLOUD COVER WILL BE THE DETERMINING FACTOR AND AT THIS TIME...IT LOOKS LIKE THERE WILL BE SUFFICIENT CLOUD COVER TO HOLD TEMPS DOWN SOME. HEATING MAY ALSO BE TEMPERED SOME IN THIS REGION AS DEWPOINTS RISE INTO THE LOWER 60S. PRECIP CHANCES WILL INCREASE DURING THE DAY ON MONDAY AS WARM AIR ADVECTION INCREASES ACROSS THE REGION...WITH SOME SPOTTY SHOWERS POSSIBLE DURING THE DAY. THE BEST CHANCE OF PRECIP WILL COME OVERNIGHT ON MONDAY AND INTO EARLY TUESDAY AS THE FRONT CROSSES THE AREA. AS STATED ABOVE...THERE ARE SOME TIMING DIFFERENCES WITH RESPECT TO THE SPEED OF THE FRONT...BUT WILL CONTINUE TO SHOW PRECIP CHANCES TRENDING DOWNWARD LATE TUESDAY AFTERNOON/EVENING. INSTABILITY APPEARS TO BE MARGINAL (AT BEST) AS THE FRONT CROSSES THE AREA MONDAY NIGHT...BUT CANNOT COMPLETELY RULE OUT AN ISOLATED THUNDERSTORM OR TWO. TEMPS MONDAY NIGHT AND TUESDAY WILL ULTIMATELY BE DETERMINED BY THE TIMING OF THE FRONT AND ASSOCIATED PRECIP AND EVENTUAL CAA. WITH THE SLIGHTLY SLOWER FRONTAL TIMING...WILL SHOW MILD TEMPS MONDAY NIGHT...GENERALLY IN THE 50S. HIGHS ON TUESDAY ARE EXPECTED TO BE IN THE MID/UPPER 50S TO LOW/MID 60S AND MAY VERY WELL OCCUR IN THE MORNING AND THEN FALL THROUGHOUT THE DAY. OVERNIGHT LOWS TUESDAY NIGHT WILL LIKELY BE IN THE MID/UPPER 30S TO NEAR 40 DEGREES. && .LONG TERM /WEDNESDAY THROUGH SATURDAY/... AS OF 300 PM SATURDAY... WEDNESDAY THROUGH THURSDAY...THEN THERE IS QUITE A BIT OF UNCERTAINTY WITH RESPECT TO THE WEATHER FOR THIS TIME FRAME. BOTH THE GFS AND ECMWF SHOW THE FRONT HANGING NEAR THE COAST WITH MULTIPLE LOW PRESSURE WAVES TRACKING ALONG IT AND SPREADING PRECIP INTO EASTERN NC...ALTHOUGH HOW FAR EAST IS IN QUESTION. THE GFS THEN SHOWS A MID LEVEL KICKER WAVE MOVING INTO THE AREA WEDNESDAY WHICH WOULD PUSH THE FRONT AND ASSOCIATED PRECIP OUT TO SEA. THE ECMWF IS ALMOST 12-18 HOURS SLOWER WITH THIS MID LEVEL WAVE...HOWEVER THIS IS SLIGHTLY FASTER THAN PREVIOUS RUNS OF THE ECMWF...SO THIS WILL HAVE TO BE MONITORED. FOR NOW...WILL GO NO MORE THAN SLIGHT CHANCE POPS FOR THIS TIME FRAME UNTIL MODELS COME INTO BETTER AGREEMENT AND WILL JUST KEEP POPS CONFINED TO THE EASTERN PORTIONS OF THE FORECAST AREA. TEMPS WILL LIKELY BE NEAR TO SLIGHTLY ABOVE NORMAL DURING THIS TIME FRAME. FRIDAY THOUGH SATURDAY...CONDITIONS THEN LOOK TO IMPROVE FOR THE END OF THE WORK WEEK AS SURFACE HIGH PRESSURE AND MID LEVEL RIDGING BUILD INTO THE AREA. MODELS THEN SHOW THE NEXT SYSTEM APPROACHING THE REGION OVER THE WEEKEND...WITH CLOUDS AND PRECIP CHANCES POSSIBLY BEGINNING TO INCREASE LATE SATURDAY (ALTHOUGH TIMING THIS FAR OUT IS ALWAYS IN QUESTION). TEMPS WILL SLOWLY MODERATE AT THE END OF THE WEEK AND ESPECIALLY INTO SATURDAY AS THE SURFACE HIGH MOVES OFFSHORE AND SOUTHERLY FLOW RETURNS TO THE AREA. && .AVIATION /00Z SUNDAY THROUGH THURSDAY/... AS OF 655 PM SATURDAY... LOWER-THAN-USUAL CONFIDENCE IN THE AVIATION FORECAST DUE TO CONFLICTING MODEL GUIDANCE. VFR CONDITIONS CURRENTLY IN PLACE OVER ALL CENTRAL NC FORECAST LOCATIONS IS LIKELY TO DROP TO SUB-VFR MAINLY AFTER MIDNIGHT. HOWEVER... JUST HOW LOW CIGS/VSBYS WILL GET WILL DEPEND ON THE EXTENT OF MID AND HIGH CLOUDS NOW MOVING INTO THE AREA FROM THE SW... WHICH WOULD FAVOR LESS RADIATIONAL COOLING AND WOULD FAVOR CIGS/VSBYS FALLING TO MVFR OR IFR RATHER THAN LIFR TONIGHT. FORECAST SOUNDINGS SUGGEST LIFR CONDITIONS... WHEREAS THE SREF PROBABILITIES AND STATISTICAL GUIDANCE FAVOR MVFR OR IFR. TAFS REFLECT A LEAN TOWARD THE LATTER SOLUTION WITH CIGS FALLING AFTER 04-06Z TO 1-2SM IN FOG/MIST WHILE CIGS DROP TO MVFR THEN IFR... AROUND 8 HUNDRED FT AGL. A FEW SHOWERS ARE POSSIBLE NEAR INT/GSO/RDU BETWEEN 07Z AND 14Z. AS SW SURFACE WINDS INCREASE TO 5-10 KTS AFTER 14Z... VSBYS WILL IMPROVE TO VFR WHILE CIGS RISE TO MVFR SLOWLY BEFORE RISING ABOVE 3 THOUSAND FT AGL AFTER 17Z... LASTING THROUGH THE AFTERNOON/EARLY EVENING. LOOKING BEYOND 00Z MONDAY... PERIODS OF ADVERSE AVIATION CONDITIONS ARE APT TO PERSIST THROUGH MID WEEK. A BREEZE FROM THE SW WILL HOLD SUNDAY EVENING AND NIGHT WITH A HIGH CHANCE OF IFR/LIFR CONDITIONS RETURNING AFTER 05Z. CIGS WILL SLOWLY RISE TO VFR BY 18Z MONDAY... THEN DROP BACK TO IFR/LIFR MONDAY EVENING AHEAD OF THE INCOMING COLD FRONT. CIGS WILL SLOWLY RISE TO MVFR THEN VFR ON TUESDAY WITH FRONTAL PASSAGE AND JUST BEHIND THE FRONT. MVFR CONDITIONS MAY RETURN TUESDAY NIGHT INTO WEDNESDAY MORNING. THEN... VFR CONDITIONS WITH HIGH PRESSURE IS LIKELY LATE WEDNESDAY THROUGH THURSDAY. -GIH && .CLIMATE... DAILY RECORD HIGHS FOR MONDAY (DECEMBER 10): RDU: 81 (2007) GSO: 78 (2007) FAY 79 (2007) && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...CBL/SEC NEAR TERM...CBL/BLS SHORT TERM...KRR LONG TERM....KRR AVIATION...HARTFIELD CLIMATE...RAH
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
646 AM EST FRI DEC 7 2012 .SYNOPSIS... A WARM FRONT WILL MOVE WESTWARD AND INTO COASTAL PORTIONS OF THE CAROLINAS LATER TODAY. WEAK LOW PRESSURE WILL FORM ALONG THE FRONT THIS EVENING...PUSHING THE BOUNDARY BACK OFFSHORE TONIGHT. WARM AND DRY CONDITIONS ARE EXPECTED SATURDAY AFTERNOON INTO EARLY TUESDAY. A COLD FRONT WILL MOVE THROUGH FROM THE WEST TUESDAY...ACCOMPANIED BY BETTER RAIN CHANCES. && .NEAR TERM /THROUGH TONIGHT/... AS OF 630 AM FRIDAY...LATEST MODELS WERE NOT UNANIMOUS WITH THEIR FORECAST FRONTAL POSITION FOR THIS AFTERNOON. 21Z FORECAST POSITIONS RANGE FROM THE RUC (15 MILES WEST OF ILM TO 15 MILES EAST OF MYR) TO THE GFS/NAM SOLUTION (GEORGETOWN TO CONWAY...WHITEVILLE AND ELIZABETHTOWN.) WHILE OUR FORECAST HIGHS TODAY HAVE A MODERATE DEGREE OF CONFIDENCE IN WILMINGTON (SHOULD BE ON THE WARM SIDE OF THE BOUNDARY) AND IN FLORENCE (SHOULD BE ON THE COLD SIDE OF THE BOUNDARY) THE AREA IN BETWEEN REMAINS LOW CONFIDENCE. PREVIOUS DISCUSSION FROM 300 AM FOLLOWS... IT IS A LOW-CONFIDENCE FORECAST TODAY OWING TO POOR MODEL INITIALIZATION...LARGE MODEL SPREAD...AND TIGHT GRADIENTS IN SURFACE TEMPERATURE EXPECTED ALONG A COASTAL FRONT. THE FRONT HAS JUST PUSHED WEST ACROSS THE FRYING PAN SHOALS BUOY IN THE PAST HOUR WHERE WINDS ARE NOW EASTERLY AND TEMPERATURES HAVE RISEN TO ALMOST 70 DEGREES. RADAR COMPOSITES SHOW AN EXPANDING AREA OF LIGHT RAIN JUST SOUTH OF CAPE FEAR PRODUCED BY LIFT ALONG THE 290-295K ISENTROPIC SURFACES. AIR PARCELS ORIGINATING AT 925 MB EAST OF GEORGETOWN ARE BEING FORCED TO ASCEND TO 850 MB BY THE TIME THEY MOVE NORTH OVER LUMBERTON. THAT`S ABOUT 75 MB OF ASCENT IN 8 HOURS TIME AND SHOULD RESULT IN SIGNIFICANT CLOUD COVER THROUGH THE DAY. PATCHES OF LIGHT RAIN SHOULD ALSO DEVELOP AND SPREAD WEST TO THE I-95 CORRIDOR BY EARLY AFTERNOON. RADAR ALSO REVEALS EMBEDDED HEAVIER SHOWERS WELL OFFSHORE...ROOTED IN CONVECTIVE INSTABILITY ENHANCED BY THE WARM WATER OF THE GULF STREAM. THESE HEAVIER SHOWERS SHOULD REMAIN OFF THE COAST THROUGH TONIGHT. HIGHS TODAY WILL BE HIGHLY DEPENDENT ON HOW MUCH INLAND PROGRESS THE COASTAL FRONT MAKES BY LATE AFTERNOON. THE 00Z GFS AND NAM APPEAR TO BE MOVING THE BOUNDARY TOO FAR INLAND...ERODING THE COLD AIR INLAND TOO QUICKLY GIVEN THE AMOUNT OF CLOUD COVER ANTICIPATED TO LINGER TODAY. THE BEST MODEL I CAN FIND IS THE 00Z NMM-EAST EXPERIMENTAL RUN THAT SHOWS THE FRONT AT 7 PM THIS EVENING ABOUT 25 MILES INLAND ACROSS SOUTHEASTERN NORTH CAROLINA...EXTENDING SOUTH ACROSS MYRTLE BEACH AND GEORGETOWN. WITH THIS IN MIND...HIGHS SHOULD RANGE FROM THE UPPER 60S IN WILMINGTON...TO THE UPPER 50S WEST OF I-95 WHERE LOW CLOUDS AND THE COOL WEDGE AIRMASS SHOULD HOLD FIRM. THE BEACHES WILL RUN AT LEAST 5 DEGREES COOLER THAN POINTS JUST A FEW MILES INLAND DUE TO WINDS BLOWING IN FROM THE COOL SHALLOW WATER NEAR THE COAST. WEAK LOW PRESSURE WILL DEVELOP OFF THE SOUTH CAROLINA COAST ALONG THE FRONT THIS EVENING. AS THE LOW MOVES NORTH OF CAPE FEAR AFTER MIDNIGHT THE FRONT WILL BE PUSHED BACK OUT TO SEA...WITH THE OLD WEDGE AIRMASS ADVECTING BACK TO THE COAST AND OFFSHORE. ANY REMAINING RAIN NEAR THE COAST SHOULD ALSO END AS THE LOW PULLS THE FRONT THROUGH. LOWS SHOULD FALL INTO THE UPPER 40S INLAND TO LOWER 50S NEAR THE COAST. && .SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/... AS OF 2:45 AM FRIDAY...A WEST TO SLIGHTLY SOUTHWESTERLY FLOW WILL PREVAIL THROUGH THE PERIOD AT THE MID LEVELS AS WEAK HIGH PRESSURE WILL BE THE FEATURE OF NOTE AT THE SURFACE. THERE WILL BE INTERVALS OF MID AND HIGH LEVEL CLOUDINESS FROM THE MOISTURE SLOWLY BUILDING FROM THE WEST...OTHERWISE...LITTLE IN THE WAY OF SIGNIFICANT WEATHER. SOUNDINGS DO SUPPORT A DECENT FOG EVENT FOR SUNDAY MORNING...BUT THE AFOREMENTIONED CLOUDINESS MAY PROVE TO BE AN IMPEDIMENT TO FORMATION. TEMPERATURE GUIDANCE IS STILL SUPPORTING WIDESPREAD 70S SUNDAY. SATURDAY THE 70S WILL MOST LIKELY BE CONFINED TO SOUTHWESTERN AREAS. && .LONG TERM /MONDAY THROUGH THURSDAY/... AS OF 2:45 AM FRIDAY...EXTENDED FORECAST CONTINUES TO CENTER AROUND THE COLD FRONT MOVING ACROSS THE AREA LATE MONDAY. MEDIUM RANGE GUIDANCE SHOWS THE GFS THE MORE PROGRESSIVE SOLUTION AND THE ECMWF SOMEWHAT SLOWER. THE 0000 UTC CYCLE OF THE OPERATIONAL GFS ALSO INTRODUCES A SECONDARY WAVE ALONG THE SOUTHERN END OF THE FRONT WHICH COULD EXTEND POPS INTO TUESDAY. IT IS CERTAINLY PLAUSIBLE AS THE UNCERTAINTY IN THIS FORECAST FOR DAYS NOW HAS BEEN THE TIMING OF SPEED MAX FEATURES ROUNDING THE PACIFIC RIDGE AND DIVING INTO THE MEAN TROUGH. OTHERWISE THE EXTENDED REMAINS ESSENTIALLY UNCHANGED WITH THE MORNING UPDATE. CHANCE POPS MONDAY FOLLOWED BY A RETURN TO SEASONAL TEMPERATURES. && .AVIATION /12Z FRIDAY THROUGH TUESDAY/... AS OF 12Z...IFR/NEAR IFR CEILINGS AT THE MYRTLES...WITH MAINLY MVFR AT THE OTHER SITES. LOOK FOR A DIURNAL RISE TO MVFR AT THE MYRTLES IN A COUPLE OF HOURS. COASTAL TROUGH CURRENTLY KICKING UP CONVECTION MAINLY OVER THE GULF AT THIS TIME. NSSL WRF SHOWS CONVECTION SKIRTING THE COAST THIS AFTERNOON AS THE TROUGH DRIFTS WESTWARD. WILL INTRODUCE A TEMPO GROUP THIS AFTERNOON FOR SHOWERS. TONIGHT...MODELS INDICATING ANOTHER ROUND OF IFR STRATUS AFTER MIDNIGHT. EXTENDED OUTLOOK...MORNING FOG/STRATUS POSSIBLE SATURDAY THROUGH MONDAY. SHOWERS POSSIBLE TUESDAY ASSOCIATED WITH A COLD FRONT. OTHERWISE VFR. && .MARINE... NEAR TERM/THROUGH TONIGHT/... AS OF 630 AM FRIDAY...NO SIGNIFICANT CHANGES HAVE BEEN MADE TO THE FORECAST. SEAS AT THE FRYING PAN SHOALS BUOY REMAIN AROUND 6 FT...SO THE ADVISORY WILL RUN FOR ANOTHER COUPLE OF HOURS. PREVIOUS DISCUSSION FROM 300 AM FOLLOWS... STRONG NORTHEAST WINDS OVER THE PAST 24 HOURS ARE FINALLY TAPERING OFF AS HIGH PRESSURE OVER COASTAL NEW ENGLAND LOSES ITS GRIP ON THE CAROLINAS. A COASTAL TROUGH LOCATED 35-45 MILES OFFSHORE WILL MOVE WESTWARD TODAY...REACHING THE NC BEACHES BY EARLY AFTERNOON...AND THE SC BEACHES BY EARLY THIS EVENING. WINDS SHOULD DIE DOWN SUBSTANTIALLY FROM THE CURRENT 15-20 KNOT SPEEDS AS THE PRESSURE GRADIENT IS MUCH MORE SLACK AROUND THE FRONT. WEAK LOW PRESSURE WILL DEVELOP THIS EVENING ALONG THE FRONT OFF THE SOUTH CAROLINA COAST...MOVING NORTHEAST OF CAPE FEAR AFTER MIDNIGHT. THIS WILL PULL THE COASTAL FRONT OFFSHORE...WITH WEST TO NORTHWEST WINDS DEVELOPING THROUGH DAYBREAK SATURDAY. THE SMALL CRAFT ADVISORY HAS BEEN EXTENDED THROUGH 9 AM THIS MORNING FOR ALL BUT THE HORRY COUNTY SC COASTAL WATERS TO ACCOUNT FOR RESIDUAL 6-FOOT SEAS STILL INFERRED FROM AREA BUOY OBSERVATIONS. IN ADDITION TO LOCAL SHORT PERIOD WIND WAVES...A 1-2 FOOT 10-SECOND EASTERLY SWELL WILL CONTINUE TO PUSH TOWARD THE COAST THROUGH TONIGHT. SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/... AS OF 2:45 AM FRIDAY...RATHER UNEVENTFUL CONDITIONS FOR MARINERS FOR THE WEEKEND AS A MODEST WESTERLY FLOW DEVELOPS SATURDAY...AROUND TEN KNOTS AT BEST...FOLLOWED BY VERY WEAK WINDS SUNDAY MORNING. SUNDAY WILL SEE MORE OF A SOUTHEAST FLOW TAKE SHAPE ALBEIT SLOWLY AS THE NEXT SIGNIFICANT SYSTEM ORGANIZES WELL TO THE WEST. SEAS OF 2-3 FEET CAN BE EXPECTED. LONG TERM /MONDAY THROUGH TUESDAY/... AS OF 2:45 AM FRIDAY...MAIN FEATURE FOR THE MARINE COMMUNITY WILL BE THE COLD FRONT MOVING ACROSS THE WATERS LATE MONDAY. SOUTHWEST WINDS OF 15-20 KNOTS WILL PRECEDE THE FRONT AND PROBABLY TOWARD THE HIGHER END OF THE RANGE. SOME MEDIUM RANGE GUIDANCE HAS BEEN TRENDING SLOWER SO THERE IS A POSSIBILITY OF A MORE PROLONGED PERIOD OF THIS SOUTHWEST FLOW. FOR TUESDAY...A SOMEWHAT MUTED NORTHWESTERLY FLOW OF 10-15 KNOTS. SEAS WILL BE HIGHEST MONDAY WITH 4-7 FEET AND THE NEED FOR A SMALL CRAFT ADVISORY. THE OFFSHORE FLOW TUESDAY WILL DIMINISH SEAS TO A RANGE OF 2-4 FEET. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...NONE. NC...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 9 AM EST THIS MORNING FOR AMZ250- 252-256. && $$ SYNOPSIS...SHK NEAR TERM...TRA SHORT TERM...SHK LONG TERM...SHK AVIATION...43
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
1239 AM EST FRI DEC 7 2012 .SYNOPSIS... WARMER AIR WILL MOVE INTO THE REGION FRIDAY AS A WEDGE OF HIGH PRESSURE WEAKENS. ABOVE NORMAL TEMPERATURES WILL RETURN THIS WEEKEND AS THE HIGH PUSHES OFFSHORE AND SOUTHERLY WINDS DEVELOP. A COLD FRONT IS EXPECTED TO END THE WARMTH LATE TUESDAY...FOLLOWED BY HIGH PRESSURE AND NEAR NORMAL TEMPERATURES NEXT WEDNESDAY AND THURSDAY. && .NEAR TERM /UNTIL 6 AM FRIDAY MORNING/... AS OF 1230 AM FRIDAY...LARGE HOLES HAVE OPENED UP IN THE OVERCAST CLOUD DECK ALONG THE COAST. A QUICK GLANCE OUT IN THE WEATHER OFFICE PARKING LOT CONFIRMS TWINKLING STARS ABOVE WITH CLOUDS NEAR THE HORIZON. SATELLITE IMAGERY SHOWS THIS IS PROBABLY A SHORT-LIVED PHENOMENON...AS CONTINUED MOISTURE ADVECTION FROM THE SOUTH AND SOUTHEAST SHOULD CLOSE THESE HOLES SOON WITH CLOUDY SKIES EXPECTED MOST OF THE NIGHT. A BATCH OF RAIN AND EMBEDDED SHOWERS SOUTH OF CAPE FEAR IS ASSOCIATED WITH WEAK ISENTROPIC LIFT PLUS SOME CONVECTIVE INSTABILITY OUT TOWARD THE GULF STREAM. DESPITE THE OVERLY-BULLISH HRRR FORECASTS OF RAIN DUMPING ACROSS THE GRAND STRAND AND CAPE FEAR REGION THE REMAINDER OF THE NIGHT...I AM ONLY FORECASTING 20-40 PERCENT COVERAGE OF RAIN TONIGHT...HIGHEST CHANCES NEAR SOUTHPORT. TEMPERATURES ARE VIRTUALLY AT THEIR LOWS CURRENTLY...AND STEADY TEMPERATURES IN THE 45-50 DEGREE RANGE ARE ANTICIPATED THROUGH DAYBREAK. PREVIOUS DISCUSSION FOLLOWS... OVERCAST CLOUD COVER FOR THE REMAINDER OF THE OVERNIGHT BASED ON LATEST SAT IMAGERY TRENDS AND 1ST LOOK AT 00Z MODEL RH FIELDS. MILD MOIST AIR TO OVERRIDE THE COOL SFC BASED LAYER TO LESS THAN 2K FT IN DEPTH WEDGE DURING THE REMAINDER OF THE OVERNIGHT. LOW LEVEL CLOUD DECK WILL DOMINATE IN THE 1K TO 3K FOOT LEVEL. WILL CONTINUE TO CARRY PATCHY LIGHT RAIN OR DRIZZLE...WITH THE HIGHER CHANCE POPS ALONG THE IMMEDIATE COAST. THIS A RESULT OF PCPN ACTIVITY DEVELOPING ALONG THE INVERTED TROF JUST OFFSHORE...THAT COULD OCCASIONALLY SPILL ONSHORE AS THE ENTIRE AREA OF PCPN GENERALLY LIFTS NORTHWARD. 850MB AND 925MB MODEL TEMP PROGS INDICATE WAA TO OCCUR OVERNIGHT...HOWEVER THE DEPTH OF THE SFC BASED COOL AIR WILL PREVENT THAT MILDER AIR FROM MIXING TO THE SFC. AS A RESULT...TEMPS MAY DROP A DEGREE OR 3 FROM CURRENT VALUES... BUT OVERALL TEMPS FOR THE REMAINDER OF THE NIGHT WILL LIKELY REMAIN STEADY. && .SHORT TERM /6 AM FRIDAY MORNING THROUGH SATURDAY NIGHT/... AS OF 3 PM THURSDAY...BIT OF A TRICKY FORECAST FOR MOST OF THE PERIOD MOST NOTABLY ON FRIDAY WITH SHALLOW COOL WEDGE IN PLACE. SUCH FEATURES ARE NOTORIOUS FOR BEING DIFFICULT TO FORECAST WITH REGARDS TO THEIR EROSION. ONE FACTOR ACTING TO SLIGHTLY BOLSTER THE STRENGTH OF THE WEDGE IS FALLING PRESSURES UP AND DOWN THE EAST COAST AS A WEAKENING UPPER LOW MOVES EAST OF FLORIDA. GUIDANCE IN PRETTY GOOD AGREEMENT THOUGH IN BRINGING THIS FEATURE ASHORE LATE IN THE DAY AND THE MILDER AIR ALONG WITH IT...POSSIBLY FOR A NON-DIURNAL LATE DAY RISE IN TEMPS...TO A FEW DEGREES ABOVE CLIMO EVEN. GIVEN THE WEDGE SCENARIO STAYED CLOSER TO/SLIGHTLY BELOW THE COOLER NUMBERS. BUT ALSO SEEING HOW THIN THE MOISTURE IS WITH LARGE BINOVCS OVER SOUTHERN ZONES A REPEAT PERFORMANCE TOMORROW VERY WELL COULD LEAD TO A SLIGHTLY MILD LATE AFTERNOON. THE ABOVE SETUP ALWAYS MAKES SOME LIGHT RAIN TO RULE OUT BUT SOME DRYNESS IN THE MID LEVEL SHOULD KEEP IT TO THE VERY LIGHT/NON-MEASURABLE REALM FOR THE MOST PART. CONFIDENCE IS HIGHER THAT THE WEDGE WILL BREAK DOWN FRIDAY NIGHT INTO SATURDAY BRINGING A BETTER CHANCE OF SOME UNSEASONABLE WARMTH. THE COPIOUS MOISTURE THAT HAD BEEN AROUND DURING MUCH OF FRIDAY IN ASSOCIATION WITH THE WEDGE WILL HAVE LITTLE TO SCOUR IT OUT SO THE SKY MAY STAY FAIRLY CLOUDY. && .LONG TERM /SUNDAY THROUGH THURSDAY/... AS OF 3 PM THURSDAY...UNSEASONABLY WARM WEATHER SUN AND MON...A RESULT OF WEAK SURFACE AND MID LEVEL RIDGING...WILL BE REPLACED BY CONDITIONS MORE TYPICAL OF EARLY DECEMBER IN THE CAROLINAS FOR THE REMAINDER OF THE PERIOD. COLD FRONT CROSSES THE REGION TUE MORNING AHEAD OF MID LEVEL LONG WAVE TROUGH MOVING EAST ACROSS EASTERN CONUS. FRONT WILL PROBABLY BE ACCOMPANIED BY A BROKEN LINE OF CONVECTION...HOW VIGOROUS THIS LINE IS REMAINS TO BE SEEN. FRONT PASSES EARLIER IN THE DAY WITH THE BEST DYNAMICS AND MOISTURE TO THE NORTH. BEST PRECIP CHANCES MAY END UP BEING ASSOCIATED WITH DIURNAL CONVECTION IN THE WARM SECTOR MON AFTERNOON. HOWEVER GIVEN THE TIME RANGE AND UNCERTAINTY WILL HOLD SLIGHT CHANCE/LOW CHANCE MON THROUGH TUE FOR NOW. MEDIUM RANGE GUIDANCE DIFFERING A BIT ON WHETHER POSITIVELY TILTED MID LEVEL TROUGH HOLDS THE FRONT NEAR THE COAST TUE NIGHT AND WED BEFORE PASSAGE OF SHORTWAVE WED NIGHT HELPS KICK THE TROUGH AXIS FARTHER OFFSHORE. EITHER WAY THE AREA SHOULD REMAIN DRY...BUT FRONT STALLED CLOSER TO THE COAST WOULD RESULT IN MORE CLOUD COVER AND COOLER HIGHS. PERIOD ENDS WITH PROGRESSIVE PATTERN ALOFT AND SURFACE HIGH BUILDING IN FROM THE NORTH. && .AVIATION /06Z FRIDAY THROUGH TUESDAY/... AS OF 06Z...PREDOMINANTLY MVFR CIGS ACROSS THE AREA WITH NORTHEAST SFC WINDS 5-10 KNOTS. CIGS ARE EXPECTED TO LOWER TO IFR ALONG THE COAST AROUND 10Z...HOPEFULLY REMAINING JUST AT/JUST ABOVE 1000 FT INLAND. THE NAM/RUC FORECASTS HAVE BEEN CONSISTENT WITH IFR CIGS AT KMYR/KCRE AND KILM. CIGS SHOULD GRADUALLY LIFT TO MVFR/VFR LEVELS BY LATE MORNING/EARLY AFTERNOON. AN INVERTED COASTAL TROUGH IS EXPECTED TO PRODUCE SHOWER ACTIVITY MAINLY OFFSHORE...BUT HAVE INCLUDED VCSH AT CRE/MYR AND SOME LIGHT SHOWERS AT ILM BEFORE DAYBREAK. AFTER 00Z TONIGHT...FOG/STRATUS WILL LIKELY IMPACT THE AREA THROUGH AND AFTER 06Z. EXTENDED OUTLOOK...MORNING FOG/STRATUS POSSIBLE SATURDAY THROUGH MONDAY. SHOWERS POSSIBLE TUESDAY ASSOCIATED WITH A COLD FRONT. OTHERWISE VFR. && .MARINE... NEAR TERM/THROUGH TONIGHT/... AS OF 1230 AM FRIDAY...VIRTUALLY NO CHANGES HAVE BEEN MADE TO THE FORECAST AT THIS EARLY HOUR. THE PREVIOUS FORECAST REMAINS IN GOOD SHAPE. PREVIOUS DISCUSSION FOLLOWS... A TIGHTENED SFC PG WILL RESIDE ACROSS THE LOCAL WATERS FOR THE REMAINDER OF THE OVERNIGHT. THIS DUE TO A SFC RIDGE AXIS...AKA THE WEDGE...EXTENDING NE-SW ACROSS THE CENTRAL CAROLINAS...AND THE INVERTED SFC TROF AXIS JUST OFFSHORE AND PARALLEL TO THE CAROLINA COASTLINES. WINDS WILL RUN NE 15 TO 25 KT AND SIGNIFICANT SEAS OF 3 TO 6 FT. EXCEPT...UP TO 7 FT ACROSS THE OUTER WATERS OFF CAPE FEAR. 41013 HAS REPORTED 8 FT SEAS THIS AFTERNOON AND ALL THIS EVENING. NEAR SHORE...SEAS WILL RUN 2 TO 3 FT SOUTH OF CAPE FEAR TO LITTLE RIVER INLET. SIGNIFICANT SEAS WILL PRIMARILY BE A FUNCTION OF THE LOCALLY PRODUCED WIND WAVES EXHIBITING 7 SECOND DOMINATING PERIODS. SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/... AS OF 3 PM THURSDAY...A WEDGE OF SURFACE HIGH PRESSURE WILL STAY ENTRENCHED ACROSS THE LANDMASS FOR MOST OF FRIDAY. MEANWHILE A SURFACE FRONT/TROUGH WILL STRENGTHEN OFFSHORE AND BEGIN TO MOVE TOWARDS THE COAST. THE SPEED AT WHICH THIS HAPPENS IS A LITTLE UNCERTAIN SINCE SHALLOW WEDGES OF COOL AIR ARE NOTORIOUSLY POORLY MODELED AND TEND TO EXIST LONGER THAN FORECASTED. MAIN EFFECT ON THE LOCAL FORECAST AREA WILL BE THE TIMING OF THE WINDS GOING FROM NE TO EAST AS THE BOUNDARY DRAWS NEARER TO THE COAST. ADDITIONAL VEERING TO SOUTHERLY IS THEN SLATED FOR FRIDAY NIGHT ALONG WITH A SMALL INCREASE IN THE WIND SPEED AS THE WEDGE LIFTS OUT AND THE LARGE HIGH OVER THE WESTERN ATLANTIC MAKES A SMALL PRESENCE ALONG THE COAST. AS A RESULT THERE COULD BE A SHORT WINDOW OF SCEC-WORTHY SEAS ALONG NORTHERN ZONES. WEST ATLANTIC HIGH PRESSURE WILL BRING EITHER SW OR W WINDS ON SATURDAY DEPENDING ON HOW FAR SOUTH A BACKDOOR COLD FRONT SINKS SOUTH OF THE MASON-DIXON LINE. LONG TERM /SUNDAY THROUGH TUESDAY/... AS OF 3 PM THURSDAY...SOUTHERLY FLOW ACROSS THE WATERS SUN AND SUN NIGHT BECOMES SOUTHWEST AND INCREASES MON AS GRADIENT TIGHTENS AHEAD OF APPROACHING COLD FRONT. ANTICIPATE A SOLID 20 KT LATER MON WITH SEAS LIKELY EXCEEDING 6 FT ACROSS WATERS OPEN TO SOUTHWEST FETCH. WOULD EXPECT SCA HEADLINE FOR ALL ZONES BEGINNING MON AFTERNOON THEN ENDING TUE MORNING AS FRONT PUSHES OFF THE COAST AND FLOW BECOMES OFFSHORE. LIMITED COLD ADVECTION IN THE WAKE OF THE FRONT WILL KEEP WINDS AND SEAS BELOW HEADLINE CRITERIA. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...NONE. NC...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 6 AM EST FRIDAY FOR AMZ256. SMALL CRAFT ADVISORY UNTIL 3 AM EST FRIDAY FOR AMZ250-252-254. && $$ SYNOPSIS...TRA NEAR TERM...DCH/TRA SHORT TERM...MBB LONG TERM...III AVIATION...BJR/TRA
AREA FORECAST DISCUSSION...UPDATED
NWS GRAND FORKS ND
919 PM CST SAT DEC 8 2012 .DISCUSSION...CONFIENCE IS NOW VERY HIGH WITH THE TRACK OF THIS SYSTEM GIVEN CURRENT OBSERVATIONS AND INCOMING 00Z MODEL RUNS. SFC LOW ACROSS SOUTHCENTRAL SOUTH DAKOTA WILL PROPAGATE EAST INTO SOUTHERN MINNESOTA ON SUNDAY. THIS PLACES THE STRONGEST FORCING (DEFORMATION) SOUTH OF THE FA WITH THE EXTREME SOUTHERN FA ON THE NORTHERN EDGE OF THE SIGNIFICANT SNOWFALL. AREAS ACROSS THE SOUTHERN PORTION OF THE WINTER STORM WARNING SHOULD GET 5-8 INCHES OF SNOW...WHILE AREAS ACROSS THE NORTHERN PORTION OF THE WARNING GET 2-5 INCHES. STRONG 850MB FRONTOGENESIS TO THE NORTH WILL SLOWLY SINK SOUTH INTO SUNDAY MORNING. ALTHOUGH SYNOPTIC FORCING IS WEAK WITHIN THIS FORCING...HIGHER SNOW RATIOS (15:1-20:1) WILL LIKELY LEAD TO 2-4 INCHES OF NEW SNOW FOR AREAS NORTH OF THE WARNING. THESE SNOWFALL TOTALS ARE CLOSE TO THE PREVIOUS FORECAST AND ONLY MINOR ADJUSTMENTS WERE PERFORMED. WINDS WILL NOT BE QUITE AS STRONG ACROSS THE FAR NORTHERN FA WITH THE EXPECTED TRACK OF THE SFC LOW FURTHER SOUTH...AND WILL REPLACE THE WINTER WEATHER ADVISORY WITH A WIND CHILL ADVISORY ACROSS THIS AREA (WIND CHILL VALUES -25F TO -35F) THROUGH 18Z. THIS LEADS TO THE MAIN QUESTION...ARE THE EXPECTED WINDS ENOUGH FOR A BLIZZARD WARNING ACROSS SOUTHEAST NORTH DAKOTA AND THE SOUTHERN RED RIVER VALLEY (SOUTH OF FARGO). CANADIAN BLOWING SNOW MODEL SUGGESTS WIND SPEEDS AROUND 32 KNOTS WILL BE NEEDED FOR A WIDESPREAD BLIZZARD. SUSTAINED WINDS LIKELY WILL BE AROUND 26 KNOTS...WITH GUSTS TO AROUND 40 KNOTS. SO...WILL THE GUSTS BE FREQUENT ENOUGH TO CREATE BLIZZARD CONDITIONS. STRONGEST SFC PRESSURE RISE MAXIMUM AND 925MB COLD AIR ADVECTION LOOK TO PASS JUST SOUTH OF THE FA...WHICH WOULD LIMIT MIXING POTENTIAL ACROSS OUR SOUTHERN FA. THIS ALL SUGGESTS THAT A WARNING IS STILL THE BEST OPTION. WILL NEED TO MONITOR THE SITUATION CLOSELY...AND NEAR BLIZZARD CONDITIONS ARE LIKELY NEAR THE SOUTH DAKOTA BORDER...BUT A WINTER STORM WARNING TAKES CARE OF THE SITUATION BEST AT THIS POINT. DID REMOVE THE BLOWING SNOW MENTION ACROSS PORTIONS OF THE NORTHERN FA WITH WIND SPEEDS SLIGHTLY LESS HERE. && .AVIATION...MVFR/IFR CONDITIONS ACROSS ALL TAF SITES ALONG WITH LIGHT SNOW WILL CONTINUE THROUGH MUCH OF THE NIGHT INTO SUNDAY MORNING. CLEARING SKIES WILL MOVE IN FROM THE NORTH...LATE TONIGHT INTO SUNDAY. WINDS WILL INCREASE FROM THE NORTH ALONG THE VALLEY...WITH BLOWING SNOW LIKELY FOR KGFK AND KFAR. && .PREV DISCUSSION... /ISSUED 309 PM CST SAT DEC 8 2012/ SHORT TERM... QUITE CHALLENGING TODAY. MODELS KEEP TRACKING LOW A BIT FARTHER SOUTH EACH RUN AND 12Z GFS AND LATEST RAP MODEL GO ALONG WITH 00Z AND 12Z EURO IN HAVING LOW JUST NORTH OR NORTHEAST OF SIOUX FALLS AT 12Z SUN. TRACK OF MID LEVEL LOW WOULD BRING HEAVIEST SNOW INTO MOSTLY NORTHERN INTO NORTHEAST AND EAST CENTRAL SOUTH DAKOTA TOWARD PERHAPS ST CLOUD AND THE NRN TWIN CITIES METRO AREA OVERNIGHT INTO SUNDAY. THUS HEAVIEST SNOW NOW JUST CLIPS THE FAR SOUTH FCST AREA IN WARNING AREA. FARTHER SOUTH TRACK GIVES A BIT MORE CONFIDENCE NOW TO LEAVING STRETCH FROM VALLEY CITY TO FARGO TO PARK RAPIDS IN ADVISORY FOR UP TO 4 INCHES WITH LESS FARTHER NORTH. NOW WILL ADD A FEW COUNTIES IN THE FAR NORTH ALONG ND/MB BORDER TO WINTER WX ADVISORY TONIGHT AS AREA THERE RECEIVED 4 INCHES OF FLUFF ACCORDING TO SPOTTERS AND WILL EASILY BLOW AROUND TONIGHT AS WINDS UP THERE INCREASE TO AROUND 20 MPH. PLUS WIND CHILLS WILL DROP TO BELOW -25F LATER TONIGHT. 925 MB WINDS FARTHER SOUTH WILL INCREASE GREATLY 06Z TO 09Z FROM NEAR GRAND FORKS SOUTH INTO ERN SD WITH 40-45 KTS THERE AND DUE TO PRESSURE GRADIENT AND COLD ADVECTION SHOULD SEE GUSTS OVER 30 KTS ESP IN SE ND IN THAT 09Z TO 18Z PERIOD. WINDS WILL HIT AFTER THE MAIN SNOW AND WITH MAIN SNOW BEING LESS IN ALL BUT FAR SOUTH THAN EARLIER THINKING STILL THINK ADV OK RIGHT NOW. COULD SEE BLIZZARD CONDITIONS DEVELOP HOWEVER BUT QUITE IFFY ON THIS...MORE OF AN OPEN COUNTRY THING VS IN TOWN AS MAIN SNOWFALL ITSELF IS JUST A BIT SOUTH. EVE SHIFT CAN MONITOR. SYSTEM WILL MOVE EAST SUNDAY AND SNOW AND WIND WILL DIMINISH...SNOW FIRST THEN WIND. VERY COLD WITH 12Z-18Z WIND CHILLS TO -30 IN THE FAR NORTHWEST FCST AREA. WILL LET MID SHIFT ISSUE ANY WC HEADLINES. DIDNT WANT TO EXTEND WINTER WX HEADLINES PAST 12Z SUN UP IN THE FAR NORTHWEST AS WINDS WILL DIMINISH THERE FIRST. HIGH PRESSURE WILL MOVE IN SUN NIGHT AND SOME SPOTS WILL GET INTO THE NEGATIVE TEENS. CLOUDS WILL MOVE IN LATE SUN NIGHT INTO MONDAY AND TUESDAY AS SEVERAL SHORT WAVES MOVE THROUGH BUT DOES LOOK MAINLY DRY. COULD BE A FEW SPITS OF -SN BUT DID NOT MENTION YET. LONG TERM...TUESDAY NIGHT THROUGH SATURDAY 12 UTC GFS/ECMWF IN REASONABLE AGREEMENT NEXT WEEK...BOTH SHOWING NORTHWEST FLOW ALOFT SHIFTING TO THE WEST/SOUTHWEST THROUGH THE PERIOD. BEST CHANCE FOR SNOW WILL BE ALONG AND NORTH OF THE HIGHWAY 2 CORRIDOR ON WEDNESDAY AS A WEAK SHORT-WAVE MOVES ACROSS SOUTHERN CANADA. THURSDAY INTO EARLY NEXT WEEKEND LOOK MAINLY DRY AS MAJORITY OF ENERGY ALOFT GETS SHUNTED TO THE SOUTH WITH FOUR CORNERS TROUGH. THIS FEATURE EJECTS NORTHEASTWARD AND INTO SOUTHEAST MN/WEST CENTRAL WI BY SATURDAY...SO WILL NEED TO WATCH FOR ANY NORTHWARD OR WESTWARD SHIFTS...REQUIRING AN INCREASE IN THE CURRENT ALL BLEND 20 POPS. TEMPERATURES WILL BE SEASONABLE ON WEDNESDAY WITH HIGHS IN THE 20S BEFORE A COOL-DOWN FOR THE LATTER HALF OF THE WEEK AFTER A COLD FRONT MOVES THROUGH WEDNESDAY NIGHT. HIGHS THURSDAY/FRIDAY WILL RANGE FROM THE SINGLE DIGITS ABOVE ZERO TO THE UPPER TEENS TO NEAR 20 DEGREES. && .FGF WATCHES/WARNINGS/ADVISORIES... ND...WINTER WEATHER ADVISORY UNTIL 6 PM CST SUNDAY FOR NDZ024-026>030- 038-039. WINTER STORM WARNING UNTIL 6 PM CST SUNDAY FOR NDZ049-052-053. WIND CHILL ADVISORY UNTIL NOON CST SUNDAY FOR NDZ006>008-014>016- 054. MN...WINTER WEATHER ADVISORY UNTIL 6 PM CST SUNDAY FOR MNZ001>003- 013>017-022>024-027-028. WINTER STORM WARNING UNTIL 6 PM CST SUNDAY FOR MNZ029>032-040. WIND CHILL ADVISORY UNTIL NOON CST SUNDAY FOR MNZ004-007. && $$ TG
AREA FORECAST DISCUSSION
NWS WILMINGTON OH
1011 PM EST SAT DEC 8 2012 .SYNOPSIS... HIGH PRESSURE WILL BUILD OVER THE GREAT LAKES IN THE WAKE OF A DEPARTING COLD FRONT TONIGHT. THIS WILL GIVE A BRIEF RESPITE TO THE RAINFALL UNTIL A WARM FRONT DEVELOPS OVER KENTUCKY EARLY SUNDAY AND THEN LIFTS NORTHWARD. LOW PRESSURE WILL THEN TRACK NORTHEAST THROUGH THE OHIO VALLEY AND ANOTHER COLD FRONT OVER THE AREA WILL BE THE FOCUS FOR MORE RAINFALL SUNDAY NIGHT AND MONDAY. && .NEAR TERM /UNTIL 6 AM SUNDAY MORNING/... SHOWERS AND A FEW THUNDERSTORMS HAVE BEEN DEVELOPING ACROSS KENTUCKY OVER THE PAST FEW HOURS WITH A WARM FRONT OVER THE AREA. EXPECT THE SHOWERS TO REMAIN MAINLY ALONG AND SOUTH OF THE OHIO RIVER INTO THE EARLY MORNING HOURS PER THE LATEST HRRR AND RAP13 RUNS...BUT THE RAIN WILL LIKELY BEGIN TO SPREAD FURTHER NORTH TOWARDS DAYBREAK. BUMPED UP POPS A BIT TO ACCOUNT FOR THIS. REST OF FORECAST LARGELY REMAINS ON TRACK WITH ONLY A FEW MINOR TWEAKS. && .SHORT TERM /6 AM SUNDAY MORNING THROUGH MONDAY NIGHT/... WARM FRONT OVER KENTUCKY LIFTS NORTH THROUGH OHIO DURING THE DAY SUNDAY AND A SURFACE LOW TRACKS EAST ALONG IT AS IT DOES. THE COMBINATION OF THE TWO WILL MEAN ANOTHER MILD DAY WITH AN EVER- INCREASING CHANCE FOR SHOWERS. ONCE THE LOW REACHES LAKE ERIE SUNDAY NIGHT...A COLD FRONT ORIENTED ALONG THE I-71 CORRIDOR WILL BE A FOCUS FOR SHOWERS AND EVEN SOME THUNDERSTORMS. RAIN AT TIMES COULD BE MODERATE IN INTENSITY AND RIVERS AND STREAMS THAT MAY BE RUNNING HIGH WILL NEED TO BE MONITORED A LITTLE CLOSER AS THE NEXT ROUND OF RAIN COMES IN. THE MODERATE RAINFALL WILL PROBABLY OCCUR IN THE LATER EVENING AS THE FLOW AT THE SURFACE AND ALOFT IS NEAR PARALLEL SOUTHWEST TO NORTHEAST. THIS WILL TAP THE AVAILABLE GULF MOISTURE WITH A STRONG TRANSPORT WIND OVER THE REGION UNTIL THE SURFACE GRADUALLY SHOWS AND EASTWARD PROGRESSION ON MONDAY IN RESPONSE TO THE COLDER AIR BEING USHERED IN ON NORTHWEST WINDS. A LARGE PORTION OF THE ATMOSPHERE WILL SEE QUITE A BIT OF SLANTWISE CONVECTION AND THE THREAT FOR THUNDER IN THESE SHOWERS IS HIGHER THAN AVERAGE...THOUGH THE SEVERE THREAT INHERENT WITH THUNDERSTORMS WILL BE QUITE MINIMAL IF IT DOES EXIST AT ALL. I TOOK NAM CAPE VALUES OVER 30 TO INDICATE THE THREAT FOR THUNDER. WITH REGARDS TO THE HEAVIER RAIN...THIS STARTED SUNDAY EVENING AND RAN THROUGH MONDAY EVENING WHERE POPS LIKELY OR HIGHER WERE BEING FORECAST. THE RAIN WILL TURN OFF NORTHWEST TO SOUTHEAST ON MONDAY WITH VERY LITTLE ACTIVITY SLATED TO REMAIN MONDAY NIGHT. THE DEEPER COLD AIR IS WELL BEHIND THE RAINFALL SO I HAVE REMOVED MENTION OF ANY SNOW. TEMPERATURES WERE ONLY MINORLY ADJUSTED AND ARE SHOWING A PRETTY GOOD CONSISTENCY BETWEEN GUIDANCE VALUES AND THE PREVIOUS FORECAST. && .LONG TERM /TUESDAY THROUGH SATURDAY/... AS THE PERIOD BEGINS...THE MODELS ARE SHOWING SFC HIGH PRESSURE BEGINNING TO PUSH INTO THE REGION. THE HIGH STRENGTHENS IT GRIP OVER THE REGION DURING THE DAY TUESDAY. THE CENTER OF THE HIGH WILL STRETCH OVER THE UPPER OHIO VALLEY BY DAYBREAK ON WEDNESDAY AND HIGH PRESSURE WILL CONTROL THE REGIONS WEATHER INTO FRIDAY. RIGHT NOW MODELS ARE IN GOOD AGREEMENT IN FORMING A SFC LOW IN THE PLAINS ON FRIDAY AND EJECTING IT OUT INTO THE WESTERN LAKES BY SATURDAY. FA WILL ONCE AGAIN BE ON THE WARM SIDE OF THE SYSTEM...SO IT LOOKS LIKE A ANOTHER SHOT OF RAIN FOR NEXT SATURDAY. TUESDAY SHOULD BE THE COLDEST DAY OF THE WEEK WITH CAA BEHIND THE DEPARTING SYSTEM. HIGH WILL ONLY BE IN THE MID 30S TO AROUND 40. MOSTLY CLEAR SKIES TUESDAY WITH THE BUILDING HIGH SHOULD ALLOW TEMPERATURES TO FALL BACK INTO THE LOWER TO MID 20S. A GRADUAL WARM UP THEN BEGINS ON WEDNESDAY AS HIGH ARE EXPECTED TO PUSH INTO THE LOWER TO MID 40S. HIGHS WILL PUSH INTO THE UPPER 40S TO LOWER 50S BY THE END OF THE WEEK. ANOTHER COOL NIGHT IS EXPECTED WEDNESDAY NIGHT WITH TEMPERATURES FALLING BACK INTO THE 20S BEFORE THE WARMER AIR BEGINS TO WORK IN AHEAD OF THE DEVELOPING SYSTEM BY THE END OF THE PERIOD. && .AVIATION /03Z SUNDAY THROUGH THURSDAY/... MVFR CEILINGS SHOULD PERSIST THROUGH THE EARLY PART OF THE TAF PERIOD. LATER IN THE EXPECT CEILINGS AND VISIBILITIES TO LOWER AS A WARM FRONT STRENGTHENS TO THE SOUTH OF THE REGION. SOME SHOWERS WILL LIFT NORTH AHEAD OF THE WARM FRONT. BUT MAIN CONCERN WILL BE IFR CEILINGS WHICH FOR THE MOST PART WILL NOT BE ABLE TO LIFT TO OR ABOVE 1000 FT UNTIL AFTER THE WARM FRONT PASSES. AND THAT IS NOT FORECAST UNTIL 15Z OR LATER. ADDITIONAL SHOWERS WILL DEVELOP LATE IN THE TAF PERIOD AS AN AREA OF LOW PRESSURE APPROACHES FROM THE WEST. SOME INSTABILITY IS EXPECTED TO DEVELOP AHEAD OF THIS LOW WHICH COULD LEAD TO A FEW THUNDERSTORMS. AT THIS POINT THE GREATEST PROBABILITY IS IN THE CINCINNATI AREA BUT A STORM CANNOT BE RULED OUT AT ANY OF THE TERMINALS. OUTLOOK...IFR CEILINGS AND MVFR VISIBILITIES LIKELY SUNDAY NIGHT WITH IMPROVEMENT TO MVFR CEILINGS ON MONDAY. MVFR CEILINGS MAY LINGER INTO MONDAY NIGHT AND TUESDAY MORNING. && .ILN WATCHES/WARNINGS/ADVISORIES... OH...NONE. KY...NONE. IN...NONE. && $$ SYNOPSIS...FRANKS NEAR TERM...KURZ SHORT TERM...FRANKS LONG TERM...SITES AVIATION...
AREA FORECAST DISCUSSION
NWS WILMINGTON OH
357 PM EST FRI DEC 7 2012 .SYNOPSIS... THE WEATHER PATTERN WILL REMAIN UNSETTLED THROUGH THE WEEKEND AS WAVES OF LOW PRESSURE AND ASSOCIATED FRONTAL SYSTEMS MOVE ACROSS THE GREAT LAKES AND THE OHIO VALLEY REGION. TEMPERATURES WILL REMAIN ABOVE NORMAL THROUGH THE WEEKEND FOLLOWED BY MUCH COLDER TEMPERATURES BY EARLY NEXT WEEK. && .NEAR TERM /UNTIL 6 AM SATURDAY MORNING/... LOCAL AND MOSAIC RADAR CONTINUE TO SHOW RAIN ACROSS THE REGION. THIS PCPN WAS THE RESULT OF A MOIST AIRMASS IN PLACE COUPLED WITH LOW LEVEL JET FORCING AND WEAK EMBEDDED DISTURBANCES WITHIN THE WEST/SOUTHWEST FLOW ALOFT. FOR TONIGHT...A WEAK AREA OF LOW PRESSURE IS FORECAST TO RIPPLE ALONG A FRONTAL BOUNDARY NEAR OUR NORTHWEST...BEING PERTURBED BY A LITTLE STRONGER S/WV PUSHES ACRS THE GREAT LAKES. HAVE GONE WITH MAINLY CATEGORICAL POPS THIS EVENING...ALTHOUGH THE LATEST HRRR SUGGESTS THAT WIDESPREAD PCPN MAY BRIEFLY TAPER LATE THIS EVENING/EARLY MORNING BEFORE THE WAVE OF LOW PRESSURE ARRIVES AND BRINGS ANOTHER ROUND OF RAIN. WILL CONTINUE TO MONITOR FOR POTENTIAL SHORT TERM ENHANCEMENT. THE OTHER WEATHER ISSUE TONIGHT WILL BE FOG POTENTIAL. DENSE FOG FORMED LAST NIGHT ACRS THE WHITEWATER AND MIAMI RIVER VALLEYS AS WELL AS INTO CENTRAL OHIO. THIS COULD HAPPEN AGAIN ANYWHERE ACRS THE AREA TONIGHT IF PCPN TAPERS OFF LONG ENOUGH AND WINDS STAY RELATIVELY LIGHT. DUE TO UNCERTAINTY...HAVE PLACED AREAS OF FOG IN THE FORECAST AND UPDATED THE HWO PRODUCT FOR POTENTIAL DENSE FOG OVERNIGHT IF CONDITIONS COME TOGETHER. TEMPERATURES TONIGHT WILL EITHER REMAIN STEADY STATE OR SLOWLY RISE AHEAD OF THE APPROACHING LOW PRESSURE WAVE. && .SHORT TERM /6 AM SATURDAY MORNING THROUGH SUNDAY NIGHT/... MODELS ARE IN FAIRLY DECENT AGREEMENT IN TERMS OF PLACEMENT...MOVEMENT AND TIMING OF MAJOR SYNOPTIC SCALE SYSTEMS THROUGH THE SHORT TERM. HAVE TAKEN A BLEND OF THE NAM...GFS AND ECMWF. WAVE OF LOW PRESSURE WILL PUSH OFF TO THE NORTHEAST ON SATURDAY. THIS WILL ALLOW A COLD FRONT TO SAG SOUTHEAST INTO THE REGION. MODELS SUGGEST THAT THE BEST CHANCE OF PCPN ON SATURDAY WILL BE ALONG AND AHEAD OF THE FRONT. THUS...HAVE LIKELY POPS GOING FOR THE ERN/SRN LOCATIONS...MAINLY FOR THE FIRST PART OF THE DAY. FOR SATURDAY NIGHT...IT LOOKS LIKE THE NRN LOCATIONS WILL HAVE A RESPITE IN THE PCPN AS COLD FRONTAL SETTLES SOUTH OF THE OHIO RIVER BEFORE MOVING BACK AS A WARM FRONT ON SUNDAY. FOR SUNDAY INTO SUNDAY NIGHT...A MORE SIGNIFICANT S/WV IS EXPECTED TO MOVE FROM THE CENTRAL PLAINS INTO THE GREAT LAKES. THIS SCENARIO WILL PERTURB A WAVE OF LOW PRESSURE OVER THE MID MS VLY. THIS PROCESS WILL PUSH OLD FRONTAL BOUNDARY NORTH THROUGH THE REGION ON SUNDAY. RETURN MOISTURE AND A MODEST LOW LEVEL JET WILL INCREASE SHOWERS FROM SOUTH TO NORTH DURING THE DAY. THERE SHOULD BE ENOUGH INSTABILITY TO MENTION THUNDER. THE SFC LOW WILL DEEPEN AS TI MOVE NE SUNDAY NIGHT...DRAGGING A COLD FRONT SE INTO THE REGION. LARGE SCALE FRONTAL CONVERGENCE AND UPPER SUPPORT WILL RESULT IN WIDESPREAD SHOWERS AND EMBEDDED THUNDERSTORMS. THERE HAS BEEN SOME CONCERN ON HOW MUCH RAIN THE REGION WILL RECEIVE THROUGH MONDAY DUE TO THE CUMULATIVE EFFECTS OF THE WEATHER SYSTEMS MOVING THROUGH THE GREAT LAKES AND OHIO VALLEY. IT APPEARS THAT AN ADDITIONAL 1 TO 2 INCHES ARE EXPECTED TONIGHT THROUGH MONDAY WITH THE HEAVIEST AMOUNTS OCCURRING ALONG AND SE OF I-71. GIVEN THAT NOVEMBER WAS DRY AND RIVER/STREAMS ARE STILL FAIRLY LOW...BELIEVE THAT THE ADDITIONAL RAINFALL WILL NOT LEAD TO ANY SUBSTANTIAL FLOODING ISSUES...ESPECIALLY WHEN IT COMES TO MAIN STEM RIVERS. ANY POTENTIAL FLOODING WOULD LIKELY BE MESOSCALE DRIVEN SUNDAY AFTERNOON AND NIGHT WHICH COULD LEAD TO MINOR ISSUES IF THE SAME LOCATIONS RECEIVE ROUNDS OF MODERATE TO LOCALLY HEAVY RAINFALL. AS FOR TEMPERATURES...HAVE GENERALLY USED A NON-DIURNAL APPROACH THROUGH THE PERIOD WITH A BLEND OF THE 2 M RAW NAM...GFS AND ECMWF. IT WILL BE ABOVE NORMAL THROUGH THE WEEKEND WITH HIGHS IN THE 50S TO THE LOWER 60S. && .LONG TERM /MONDAY THROUGH FRIDAY/... A WET WEATHER PERIOD WILL COME TO AN END MONDAY...LEADING TO DRY CONDITIONS AND INCREASING TEMPERATURES THROUGH THE REST OF THE WEEK. THE OVERALL MODEL TREND IN THE PAST 24 HOURS HAS BEEN FOR A SLIGHTLY EARLIER COLD FRONTAL PASSAGE ON MONDAY MORNING. THE TIMING DIFFERENCES ARE STILL QUITE SMALL BETWEEN THE VARIOUS MODELS...SO CONFIDENCE IN THE MONDAY FORECAST IS FAIRLY HIGH. BY 12Z...THE FRONT WILL BE CLOSE TO CLEARING THE CWA...SO ANY THREAT FOR THUNDER WILL BE LIMITED TO THE FIRST FEW HOURS AFTER DAYBREAK IN THE FAR SOUTHEAST CORNER. TEMPERATURES WILL FALL THROUGH THE DAY...THANKS TO THE COLD ADVECTION BEHIND THE FRONT...THOUGH TEMPS IN THE NORTHWEST MAY END UP STEADY BY AFTERNOON (BEFORE THE TYPICAL DIURNAL TEMPERATURE DROPS BEGIN). THE FORECAST COMPLICATION FOR THIS WEATHER SYSTEM REMAINS WITH THE BACK SIDE SHORTWAVE ON MONDAY NIGHT INTO TUESDAY. THE MID LEVEL TROUGH THAT WILL FOLLOW THE COLD FRONT (AND ITS ATTACHED SURFACE LOW MOVING THROUGH THE LOWER GREAT LAKES) HAS BEEN MODELED WITH A FEW SUBTLE DIFFERENCES...PRESENTING SOME CHALLENGES IN THE PRECIPITATION FORECAST ON THE BACK SIDE OF THE FRONT. THIS SECONDARY TROUGH AXIS (AS OPPOSED TO THE ONE DRIVING THE SURFACE LOW) HAS CONSISTENTLY BEEN DEPICTED WITH A GREATER SHARPNESS ON THE ECMWF (HIGHER AMPLITUDE AND SHORTER WAVELENGTH). THE GFS DEPICTION IS MUCH BROADER...AND DOES NOT ALLOW FOR ADDITIONAL SURFACE LOW PRESSURE DEVELOPMENT OVER THE SOUTHERN APPALACHIANS LIKE THE ECMWF. TEMPERATURES MONDAY NIGHT ARE CERTAINLY COLD ENOUGH TO SUPPORT SNOW...SO IF THE ECMWF SOLUTION WERE TO VERIFY...SOME LIGHT ACCUMULATIONS WOULD BE POSSIBLE. THE LONGWAVE PATTERN WILL FLIP FROM TROUGH TO RIDGE OVER THE EASTERN CONUS BY THE MIDDLE OF THE WEEK. THE LARGE SCALE PATTERN HAS BEEN STABLE IN THE VARIOUS SOLUTIONS...AND THOUGH THE GFSE MEMBERS SHOW SOME SPREAD IN THE NUMBERS...THE PATTERN IS IDENTICAL IN ALMOST ALL CASES. THIS LEADS TO INCREASING CONFIDENCE IN DRY WEATHER WITH SURFACE HIGH PRESSURE NOSING IN FROM THE SOUTH...AND BECOMING FIRMLY ESTABLISHED OVER THE EASTERN CONUS BY THURSDAY. THIS WILL ALLOW FOR SOUTHWESTERLY FLOW TO INCREASE TEMPERATURES OVER THE OHIO VALLEY...GOING ABOVE NORMAL BY THE END OF THE WEEK. && .AVIATION /21Z FRIDAY THROUGH WEDNESDAY/... BROAD SCALE LIFT AHEAD A STALLED CDFNT CONTINUES TO PRODUCE A LARGE AREA OF RAIN AND IFR CLOUDS OVER THE TAFS. LATEST RADAR LOOP IS SHOWING A BREAK FROM THE STEADIER RAINS WORKING NE FROM CENTRAL KY. MIGHT SEE CIGS RISE TO MVFR OVER THE NEXT FEW HOURS AS THIS AREA WORKS INTO CVG/LUK. OVERNIGHT A SFC WAVE WORKS NE ALONG THE FRONT. MODELS ARE USING THIS AS MEANS TO KICK THE PCPN EWD. THE NAM AND RAP ARE THE MOST AGGRESSIVE WITH THE DRYING BEFORE 12Z...WHILE THE OTHER MODELS LINGER PCPN CHANCE THRU 18Z. WENT WITH A BLEND OF THE SOLUTIONS...BY BACKING OFF ON THE PREVAILING PCPN AFT 00Z...BUT KEPT A VCSH. AM AFRAID WITH THE PCPN CHANCE LOWERING OVERNIGHT THAT THE DENSE FOG THAT AFFECTED MANY OF THE TAFS THIS MORNING WILL RETURN. BROUGHT LIFR VSBYS AND CIGS BACK INTO THE NRN TAFS AROUND 06Z. AS SFC WAVE GOES BY AROUND 12Z SATURDAY...WINDS PICK UP AND TURN TO A WESTERLY DIRECTION. THIS SHOULD HELP DISSIPATE THE DENSE FOG DURING SATURDAY MORNING. OUTLOOK...MVFR/IFR CIGS AND VSBYS POSSIBLE SATURDAY NIGHT INTO MONDAY. A THUNDERSTORM IS POSSIBLE LATE SUNDAY AFTERNOON INTO SUNDAY NIGHT. && .ILN WATCHES/WARNINGS/ADVISORIES... OH...NONE. KY...NONE. IN...NONE. && $$ SYNOPSIS...HICKMAN NEAR TERM...HICKMAN SHORT TERM...HICKMAN LONG TERM...HATZOS AVIATION...SITES
AREA FORECAST DISCUSSION
NWS WILMINGTON OH
124 PM EST FRI DEC 7 2012 .SYNOPSIS... A FRONTAL BOUNDARY WILL REMAIN DRAPED ACROSS THE OHIO VALLEY THROUGH THE WEEKEND. MOIST SOUTHWESTERLY FLOW WILL INTERACT WITH THE BOUNDARY TO PRODUCE WIDESPREAD PRECIPITATION ACROSS THE REGION. A COLD FRONT WILL PUSH EAST THROUGH THE AREA ON MONDAY...RESULTING IN A DECREASING CHANCE OF PRECIPITATION AND COLDER TEMPERATURES. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... AREAS OF DENSE FOG CONTINUE TO LINGER ACROSS SECTIONS OF THE FA. THE LATEST ROUND OF OBSERVATIONS SHOWED SOME IMPROVEMENTS...ESPECIALLY IN WEST CENTRAL OHIO OVER TO CENTRAL OHIO. ACROSS THE WHITEWATER AND MIAMI VALLEYS THERE WERE STILL NUMEROUS 1/4 MILE OBS. HOWEVER THE TREND LOOKS LIKE THINGS ARE BEGINNING TO IMPROVE...SO ALLOWED THE DENSE FOG ADVISORY TO EXPIRE AND COVERED THE FOG WITH A SPECIAL WEATHER STATEMENT. THE STEADIER RAINS HAVE BEEN CONFINED TO NRN KY AND SE INDIANA INTO SRN OH. MODELS ARE INDICATING THAT THE PCPN SHOULD INCREASE IN COVERAGE AS THE DAY PROGRESSES AND THE LATEST RADAR LOOP IS SHOWING SOME SIGNS OF THAT. LEFT OVERALL POPS THE SAME...100 ACROSS THE S AND 80 TO 90 IN THE NW. DROPPED TEMPS A COUPLE OF DEGREES TODAY BASED ON CURRENT TEMPERATURES AND LATEST TEMPERATURE GUIDANCE. WENT WITH HIGHS IN THE UPPER 40S N AND MID 50S IN NRN KY. && .SHORT TERM /6 PM THIS EVENING THROUGH MONDAY/... A WAVE OF LOW PRESSURE WILL RIDE EASTWARD ALONG THE BOUNDARY THIS EVENING...KEEPING WIDESPREAD PCPN GOING THROUGH MUCH OF TONIGHT. AS THE WAVE PUSHES OFF TO THE EAST LATER TONIGHT THOUGH...WE COULD BEGIN TO SEE PCPN TAPER OFF FROM THE NORTHWEST LATE TONIGHT INTO SATURDAY MORNING AS THE BETTER LOW LEVEL JET DYNAMICS ALSO SHIFT OFF TO THE EAST. WILL THEREFORE TRIM POPS BACK A BIT FOR SATURDAY...PARTICULARLY ACROSS THE NORTH. HOWEVER...THE BOUNDARY WILL REMAIN DRAPED ALONG THE OHIO RIVER SO WILL HANG ON TO SOME BETTER POPS THERE. MODELS HAVE BACKED OFF SOME WITH THE ELEVATED CAPES...ALTHOUGH 850 MB LI/S DO APPROACH ZERO UP TO ABOUT THE OHIO RIVER. WILL THEREFORE TRIM BACK THUNDER CHANCES TO JUST OUR FAR SOUTH...PRIMARILY FOR SATURDAY AFTERNOON. A STRONGER SURFACE LOW WILL WORK EAST ALONG THE BOUNDARY SATURDAY NIGHT INTO SUNDAY...BRINGING YET ANOTHER WAVE OF PCPN TO OUR REGION. SOME MODEL DIFFERENCES DO EXIST ON THE EXACT TRACK OF THIS LOW...BUT THE GENERAL TREND IS FOR IT TO LIFT UP ACROSS NORTHWESTERN PORTIONS OF OUR FA. THIS WILL HELP AT LEAST THE SOUTHEASTERN PORTION OF OUR FA TO GET INTO THE WARM SECTOR THROUGH THE DAY ON SUNDAY. THIS WILL ALLOW FOR SOME SLIGHTLY WARMER TEMPERATURES AND THE POSSIBILITY OF AN ISOLATED THUNDERSTORM AS WE MAY DESTABILIZE A BIT. AS THE LOW LIFTS OFF TO THE NORTHEAST...IT WILL HELP PULL A COLD FRONT DOWN ACROSS OUR AREA LATE SUNDAY NIGHT INTO MONDAY. PCPN CHANCES WILL BEGIN TO DECREASE FROM THE NORTHWEST THROUGH THE DAY ON MONDAY AS DRIER AIR PUSHES IN BEHIND THE FRONT. THIS WILL ALSO BE ACCOMPANIED BY SOME CAA...BUT LOW LEVELS SHOULD REMAIN WARM ENOUGH TO KEEP ANY PCPN RAIN THROUGH THE DAY ON MONDAY. IT LOOKS LIKE THE HEAVIEST PCPN THROUGH THE WEEKEND WILL SET UP ACROSS THE SOUTHEASTERN HALF OF OUR FA. PWS WILL BE RUNNING 200 TO 250 PERCENT OF NORMAL AT TIMES THROUGH SUNDAY AND AS A RESULT...SOME LOCALLY HEAVY RAINFALL WILL BE POSSIBLE. BY THE TIME THE RAIN ENDS...WE MAY VERY WELL END UP WITH A SWATH OF 3 TO 4 INCHES OF RAIN SOMEWHERE ACROSS OUR SOUTHEAST. GIVEN THE RECENT DRY CONDITIONS THOUGH...12 HOUR FFG IS MAINLY RUNNING IN THE 2.5 TO 4 INCH RANGE WITH 24 HR FFG EVEN HIGHER. THUS...UNLESS PCPN BECOMES MORE CONVECTIVE THAN CURRENT THINKING...BELIEVE OVERALL FLOOD THREAT WILL REMAIN ON THE LOW END. && .LONG TERM /MONDAY NIGHT THROUGH THURSDAY/... THE MID LEVEL TROUGH THAT WILL FOLLOW THE FRONT (AND ITS ATTACHED SURFACE LOW MOVING THROUGH THE GREAT LAKES) HAS BEEN MODELED WITH A FEW SUBTLE DIFFERENCES...PRESENTING SOME CHALLENGES IN THE PRECIPITATION FORECAST ON THE BACK SIDE OF THE FRONT. THOUGH ONE AXIS CAN BE DEPICTED NEAR AND ASSOCIATED WITH THE PRIMARY SURFACE LOW...THE 12Z ECMWF DEPICTS A SHARPER AXIS WITH THE BASE OF THE TROUGH BEHIND THE COLD FRONT. THIS LEADS TO THE GENESIS OF A SURFACE LOW OVER THE TENNESSEE VALLEY AND SOUTHERN APPALACHIANS...WHICH HAS ENOUGH OF AN IMPACT OVER OUR REGION TO SPREAD ADDITIONAL PRECIPITATION IN BEHIND THE FRONT. THIS FEATURE IS ALSO SHOWN ON THE 12Z GFS...THOUGH IT IS NOT AS AMPLIFIED. IF THIS OCCURS...THE CHANCES OF SNOW WILL INCREASE...AS TEMPERATURES MONDAY NIGHT ARE CERTAINLY COLD ENOUGH TO SUPPORT SNOW AS THE PRIMARY (OR ONLY) PRECIPITATION TYPE. && .AVIATION /18Z FRIDAY THROUGH WEDNESDAY/... BROAD SCALE LIFT AHEAD A STALLED CDFNT CONTINUES TO PRODUCE A LARGE AREA OF RAIN AND IFR CLOUDS OVER THE TAFS. LATEST RADAR LOOP IS SHOWING A BREAK FROM THE STEADIER RAINS WORKING NE FROM CENTRAL KY. MIGHT SEE CIGS RISE TO MVFR OVER THE NEXT FEW HOURS AS THIS AREA WORKS INTO CVG/LUK. OVERNIGHT A SFC WAVE WORKS NE ALONG THE FRONT. MODELS ARE USING THIS AS MEANS TO KICK THE PCPN EWD. THE NAM AND RAP ARE THE MOST AGGRESSIVE WITH THE DRYING BEFORE 12Z...WHILE THE OTHER MODELS LINGER PCPN CHANCE THRU 18Z. WENT WITH A BLEND OF THE SOLUTIONS...BY BACKING OFF ON THE PREVAILING PCPN AFT 00Z...BUT KEPT A VCSH. AM AFRAID WITH THE PCPN CHANCE LOWERING OVERNIGHT THAT THE DENSE FOG THAT AFFECTED MANY OF THE TAFS THIS MORNING WILL RETURN. BROUGHT LIFR VSBYS AND CIGS BACK INTO THE NRN TAFS AROUND 06Z. AS SFC WAVE GOES BY AROUND 12Z SATURDAY...WINDS PICK UP AND TURN TO A WESTERLY DIRECTION. THIS SHOULD HELP DISSIPATE THE DENSE FOG DURING SATURDAY MORNING. OUTLOOK...MVFR/IFR CIGS AND VSBYS POSSIBLE SATURDAY NIGHT INTO MONDAY. A THUNDERSTORM IS POSSIBLE LATE SUNDAY AFTERNOON INTO SUNDAY NIGHT. && .ILN WATCHES/WARNINGS/ADVISORIES... OH...NONE. KY...NONE. IN...NONE. && $$ SYNOPSIS...JGL NEAR TERM...SITES SHORT TERM...JGL LONG TERM...HATZOS AVIATION...SITES
AREA FORECAST DISCUSSION
NWS GREENVILLE-SPARTANBURG SC
726 PM EST SAT DEC 8 2012 .SYNOPSIS... WARMING SOUTHWEST FLOW WILL PERSIST OVER THE REGION THIS WEEKEND. SHOWER CHANCES ARE EXPECTED TO INCREASE BY MONDAY OUT AHEAD OF AN APPROACHING COLD FRONT. COOLER HIGH PRESSURE WILL MOVE BACK INTO THE CAROLIANS FOR MID WEEK. && .NEAR TERM /THROUGH SUNDAY/... 645 PM UPDATE...THE SHOWER ACTIVITY HAS DECREASED OVER THE AREA THIS EVENING AND THUS POPS HAVE BEEN LOWERED ACCORDINGLY. STILL EXPECT MOSTLY CLOUDY SKIES WITH AREAS OF FOG DEVELOPING ACROSS MUCH OF OUR CWA THROUGH THE OVERNIGHT. THE FOG COULD BECOME DENSE BY LATE TONIGHT MAINLY OVER LAKE REGIONS AND NC MOUNTAIN VALLEYS AND NORTHERN NC PIEDMONT. 500 PM UPDATE...A BAND OF LIGHT PRECIP HAS MOVED INTO THE UPSTATE SC AND NE GEORGIA THIS AFTERNOON AND IT WILL CONTINUE TO PROGRESS EAST ACROSS SC PEDIMENT THROUGH TONIGHT. PRECIP AMOUNTS SHOULD BE LIGHT AND SOME LOCAL PATCHES OF FOG COULD ACCOMPANY THE BAND OF PRECIP. THE LATEST RUC INDICATES THAT THE SHOWER ACTIVITY WILL DECREASE BY LATE TONIGHT. ANOTHER AREAS OF FOG WILL DEVELOP ACROSS MUCH OF OUR CWA TONIGHT INTO TOMORROW MORNING. AS OF 200 PM...A PLUME OF GULF MOISTURE CAN BE SEEN ON VISIBLE SATELLITE IMAGERY STREAMING WITHIN LLVL SWLY RETURN FLOW...WITH LEADING EDGE OF STRATUS AND LGT SHWRS ENTERING THE WRN PORTIONS OF THE CWFA. BOTH THE NAM AND GFS KEEP MOST OF THE ASSOCIATED ISENT LIFT AND RH CONFINED TO THE SW NC MTNS AND UPR SAVANNAH VLY INTO THIS EVENING...AS FLOW HAS ANTICYCLONIC CURVATURE AND HAS DOWNSLOPE COMPONENT TO THE EAST. WITH THAT SAID...OVERALL INCREASING CLOUD COVER AND POP IS EXPECTED ACRS THE ENTIRE AREA TNGT...AS A BRIEF PERIOD OF ISENT LIFT AND RH TRANSLATES WEST TO EAST ACRS THE AREA. TEMPS WILL BE 10-15 DEG ABOVE NORMAL OVERNIGHT...DROPPING ONLY INTO THE MID 40S TO LWR 50S. SUNDAY...GUIDANCE SHOWS THE CWFA COMPLETELY WITHIN THE WARM SECTOR OF A DEVELOPING LOW PRES SYS OVR THE MID MS VLY. ISENT LIFT WEAKENS AND DEEPER RH SHIFTS EAST. FCST SNDGS DO SHOW SOME SBCAPE...ESP ACRS THE PIEDMONT...AS CLOUDS BREAK OUT AND TEMPS WARM INTO THE UPR 60S TO NEAR 70. HOWEVER...A MID LVL INVERSION IS LIKELY TO CAP ANY DEEPER CONVECTION. BESIDES LIMITED INSTBY...NO SIGNIFICANT MID OR UPR LVL FORCING....AND LLVL LIFT WILL BE CONFINED TO SWLY UPSLOPE FLOW IN THE SW NC MTNS. SO I HAVE POPS TAPERING OFF FROM CHC MTNS AND SLGT CHC PIEDMONT IN THE MORNING TO ONLY A SLGT CHC IN THE NC FOOTHILLS/NW PIEDMONT BY EARLY EVENING. && .SHORT TERM /SUNDAY NIGHT THROUGH TUESDAY/... AS OF 300 PM SATURDAY...THE MAIN FEATURE FOR THE SHORT RANGE CONTINUES TO BE THE COLD FRONTAL PASSAGE LATE MONDAY OR MONDAY NITE. THE GUIDANCE IN GENERAL SEEMS TO HAVE SLOWED SLIGHTLY WITH FROPA. THAT SAID...THERE IS STILL SOME SPREAD IN THE TIMING OF THE FRONT. THERE IS ALSO DISAGREEMENT ON THE DEVELOPMENT OF A SFC WAVE AND WHETHER OR NOT IT MOVES ACROSS THE CWFA. THE GUIDANCE DOES AGREE THAT ANY LINGERING LIGHT PRECIP SUNDAY EVENING WILL END BEFORE MIDNIGHT AS LIFT DIMINISHES AND LOW LEVEL MOISTURE BECOMES SHALLOW. HOWEVER...DEEPER MOISTURE AND FORCING ASSOCIATED WITH THE APPROACHING FRONT WILL MOVE INTO THE MTNS AFTER MIDNIGHT SO PRECIP CHC RETURNS BY DAYBREAK. WITH THE CONTINUED CLOUDS...SLY FLOW AND HIGH THICKNESS VALUES...LOWS WILL BE 10 TO 20 DEGREES ABOVE NORMAL. WITH THE FROPA TENDING TO SLOW...THIS ALSO SLOWS THE INCREASE IN MOISTURE AND FORCING OUTSIDE OF THE MTNS. THEREFORE...DO NOT BRING ANY CHC POP TO THE NC PIEDMONT AND ERN UPSTATE UNTIL LATE AFTERNOON WITH CHC ACROSS THE FOOTHILLS AND WRN UPSTATE BY EARLY AFTERNOON. THERE IS AGREEMENT THAT THE MTNS WILL SEE PRECIP ON MONDAY...BUT IT IS SLOWED AS WELL...SO SHOW A SLOW INCREASE THRU LIKELY TO CAT POP BY LATE IN THE DAY. THERE IS STILL LITTLE IN THE WAY OF SFC INSTABILITY...BUT THERE LOOKS TO BE SOME WEAK ELEVATED INSTABILITY AS LAPSE RATES INCREASE THRU THE DAY. THUNDER COULD DEVELOP JUST ABOUT ANYWHERE EXCEPT THE NRN FOOTHILLS AND ALL BUT THE FAR SWRN NC MTNS. THE FRONT LOOKS TO MOVE ACROSS THE CWFA MON NITE. SHEAR STILL EXPECTED TO BE VERY STRONG WITH SOME HELICITY DEVELOPING. WITH THE WEAK ELEVATED INSTABILITY...SVR QLCS STORMS COULD DEVELOP. IF THE SFC LOW FORMS ALONG THE FRONT AND MOVES ACROSS THE I-85 OR SOUTH CORRIDOR...THEN SVR CHC WOULD INCREASE AS LOW LEVEL FORCING AND HELICITY COULD BE HIGHER. THIS COULD ALSO SLOW THE MOVEMENT OF THE FRONT KEEPING SVR CHC INTO THE EVENING OR EVEN LATER. HAVE LIMITED CAT POP TO THE MTNS FOR THE EVENING AND LIKELY ALL OTHER AREAS GIVEN THE EXPECT TIMING UNCERTAINTY. THE GUIDANCE AGREES THAT LOWS MON NITE AND PARTIAL THICKNESSES WILL BE HIGHER THAN PREV FCST. IN ADDITION...GUIDANCE IS TRENDING AWAY FROM ANY TRADITIONAL NW FLOW TYPE PRECIP. THEREFORE... HAVE REMOVED ANY SNOW MENTION LATE MON NITE. PRECIP SHUD DIMINISH TUE MORNING WITH ONLY SOME LINGERING ISOLATED SHRA TUE AFTERNOON SOUTH OF I-85. HIGHS SHUD BE WARMER THAN EARLIER EXPECTED AS WELL...NEAR NORMAL MTNS AND 5 TO 10 DEGREES ABOVE NORMAL ELSEWHERE. && .LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/... AT 240 PM EST SATURDAY...THE AFOREMENTIONED FRONTAL BOUNDARY SHOULD GRADUALLY GET A PUSH EAST TUESDAY NIGHT...AS A SECONDARY UPSTREAM TROF INFLUENCES SENSIBLE WEATHER. THIS SHOULD CONCLUDE PRECIPITATION CHANCES ACROSS OUR FORECAST AREA (FA). ALTHOUGH PRECIPITATION WILL EITHER END OR EXIT...SOUNDING DATA SUGGESTS CLOUDS WILL LINGER MUCH OF TUESDAY NIGHT...AND PLAN TO HOLD THAT LINE. A LARGE AREA OF SURFACE HIGH PRESSURE WILL THEN SETTLE ACROSS OUR FORECAST AREA (FA) WEDNESDAY AND THURSDAY...WHILE A FLAT 500 MB RIDGE PREVAILS. THIS SHOULD SPELL QUIET WEATHER CONDITIONS DURING MID WEEK. AS WE REACH TOWARD THE START OF NEXT WEEKEND...THE H5 RIDGE WILL HAVE SHIFTED OFF INTO THE ATLANTIC...AS WELL AS THE SURFACE HIGH. SOUTHWESTERLY FLOW AT THE SURFACE AND ALOFT WILL BEGIN TO DRIVE DEEPER MOISTURE INTO OUR REGION FRIDAY NIGHT...AND WILL PROBABLY LAST THROUGH MUCH OF THE WEEKEND. WARM AIR ADVECTION PRECIPITATION MAY BREAK OUT OVER THE NC MOUNTAINS IN THE WEE HOURS SATURDAY MORNING. INCOMING CLOUDS SHOULD CAP TEMPERATURES ABOVE FREEZING...SO AT THIS POINT WE ARE PAINTING LIQUID AS THE PRECIPITATION TYPE. THE WARM AIR ADVECTION PATTERN WILL THEN GRADUALLY ENCOMPASS MUCH OF OUR FA SATURDAY AND SATURDAY NIGHT WITH A CHANCE OF SHOWERS. WILL HOLD POPS IN THE CHANCE FIELD THIS FAR OUT...BUT WOULD NOT BE SURPRISED FOR A MORE ROBUST EPISODE. A COLD FRONT WILL THEN BE APPROACHING / OR CROSSING / OUR REGION LATE SATURDAY NIGHT OR BEYOND. THE GFS IS VERY ROBUST WITH ITS PRECIPITATION FIELDS WHILE THE NEW EUROPEAN MODEL...ALTHOUGH NOT AS BULLISH...HAS BROUGHT MORE QPF INTO OUR FA AT THE START OF NEXT WEEKEND...COMPARED TO ITS 00Z RUN. THERE SEEMS TO BE VERY LITTLE TO QUIBBLE WITH AS FAR AS TEMPERATURES ARE CONCERNING...WITH SOME MINOR ADJUSTMENTS DURING THOSE PERIODS WHEN CLOUDS ARE EXITING OR ENTERING THE FA. && .AVIATION /01Z SUNDAY THROUGH THURSDAY/... AT KCLT...VFR CONDITIONS WILL CONTINUE OVERNIGHT AND INTO SUN MORNING. THE LATEST GUIDANCE INDICATES THAT LIGHT SW WINDS WILL CONTINUE THROUGH THE OVERNIGHT HOURS WHICH SHOULD LEAD TO PREVAILING VFR CEILINGS AND VIS. SOME PATCHY FOG MAY DEVELOP TOWARD DAYBREAK BUT NOT EXPECTING ANY VSBY RESTRICTIONS AT THIS TIME. INCREASING SOUTHERLY ISENTROPIC LIFT WILL RESULT IN CLOUD CEILINGS LOWERING TO 2K FT IN MVFR CONDITION BY 18Z. ELSEWHERE...LIGHT SCATTERED SHOWERS HAVE DIMINISHED ACROSS SC PIEDMONT THIS EVENING. HOWEVER ANOTHER ROUND OF SHOWER ACTIVITY MAY RETURN TO NE GA AND WESTERN NC MTNS BY LATE TONIGHT. GUIDANCE INDICATES THAT AREAS OF DENSE FOG WILL DEVELOP ACROSS NC MOUNTAIN VALLEYS AND NORTHERN NC PIEDMONT TOWARD DAYBREAK WHICH SHOULD LEAD TO VSBY RESTRICTIONS OVER KAVL AND KHKY TERMINALS. ELSEWHERE WILL SEE PREVAILING VFR CONDITIONS OVERNIGHT THOUGH PATCHY FOG IN BRIEF MVFR CONDITIONS MAY DEVELOP TOWARD DAYBREAK. ANY FOG SHOULD BURN OFF SHORTLY AFTER SUNRISE. INCREASING SOUTHERLY ISENTROPIC LIFT AND LLVL MOISTURE ADVECTION WILL SUPPORT MVFR CEILINGS BY LATE SUN MORNING..IF NOT BY EARLY AFTERNOON. LIGHT SW WINDS WILL CONTINUE OVERNIGHT ACROSS THE PIEDMONT WITH CALM CONDITIONS OVER NC VALLEYS. WINDS WILL INCREASE ACROSS ALL TERMINALS BY EARLY SUN AFTERNOON. OUTLOOK...CONDITIONS ARE EXPECTED TO IMPROVE TO VFR ON SUNDAY. THEN PATCHY FOG AND STRATUS WILL BE POSSIBLE AGAIN MONDAY MORNING. A STRONG COLD FRONT WILL ENTER THE REGION ON MONDAY AND PUSH THRU OVERNIGHT MONDAY NIGHT...ACCOMPANIED BY SHOWERS AND THUNDERSTORMS ALONG WITH GUSTY WINDS. AN EXPERIMENTAL AVIATION FORECAST CONSISTENCY TABLE SHOWING THE PERCENTAGE OF GUIDANCE MEMBERS AGREEING WITH THE SCHEDULED ISSUANCE CATEGORY IS AVAILABLE AT FOLLOWING LINK (USE LOWER CASE)... WWW.WEATHER.GOV/GSP/AVIATION/TABLES.HTM && .GSP WATCHES/WARNINGS/ADVISORIES... GA...NONE. NC...NONE. SC...NONE. && $$ SYNOPSIS...JPT NEAR TERM...ARK/JOH SHORT TERM...RWH LONG TERM...TS AVIATION...JOH
AREA FORECAST DISCUSSION
NWS SAN ANGELO TX
1247 PM CST FRI DEC 7 2012 .UPDATE... LATEST SATELLITE AND SURFACE DATA INDICATE CONDITIONS ARE IMPROVING ACROSS WEST CENTRAL TEXAS. THE STRATUS HAS ALL BUT DISSIPATED...WITH ONLY REMNANTS REMAINING OVER THE HEARTLAND. ALOFT...SATELLITE DATA INDICATE HIGHER CLOUD STREAKS CONTINUE ACROSS MUCH OF WEST TEXAS. AT THE SURFACE ACROSS WEST CENTRAL TEXAS...TEMPERATURES AND DEWPOINT HAVE INCREASED SLIGHTLY FASTER THAN WE WERE THINKING. PLUS...SURFACE WINDS ACROSS WEST CENTRAL TEXAS ARE STILL VERY LIGHT AND VARIABLE. BASED ON SURFACE DEWPOINT ANALYSIS...THE OLD FRONTAL BOUNDARY LIKELY LIES SOMEWHERE NEAR A COLEMAN TO ROBERT LEE LINE. THE RUC INDICATES SURFACE WINDS WILL REMAIN VERY LIGHT AND VARIABLE FOR THE REMAINDER OF TODAY. I MADE SOME ADJUSTMENTS TO A FEW GRID ELEMENTS FOR THE REMAINDER OF TODAY TO BRING THEM IN LINE WITH TRENDS OVER THE LAST COUPLE HOURS. I BELIEVE AFTERNOON HIGHS STILL LOOK REASONABLE. SO...I DID NOT CHANGE THAT GRID. THE LATEST ZONE...POINT FORECAST MATRIX...AND TABULAR STATE FORECAST PRODUCTS REFLECT MY GRID ADJUSTMENTS. HUBER && .PREV DISCUSSION... /ISSUED 1202 PM CST FRI DEC 7 2012/ DISCUSSION... LOOK FOR STRATUS TO BRING MVFR CEILINGS BACK TO SOME AREAS OF WEST CENTRAL TEXAS EARLY TOMORROW MORNING. AVIATION BELOW HAS DETAILS. AVIATION... EXPECT VFR CONDITIONS THIS AFTERNOON AND TONIGHT ACROSS WEST CENTRAL TEXAS...BEFORE RETURNING STRATUS BRINGS MVFR CEILINGS BACK INTO SOME OF WEST CENTRAL TEXAS EARLY TOMORROW MORNING. A STALLED FRONTAL BOUNDARY IS PRODUCING VERY LIGHT AND VARIABLE SURFACE WINDS ACROSS WEST CENTRAL TEXAS THIS MORNING. THE NAM AND RUC SURFACE DATA INDICATE THIS SURFACE BOUNDARY WILL REMAIN OVER WEST CENTRAL TEXAS FOR MOST OF THE NEXT 24 HOURS. THUS...PLAN FOR MAINLY LIGHT AND VARIABLE SURFACE WINDS FOR THE NEXT 24 HOURS. AROUND SUNRISE TOMORROW MORNING...WATCH FOR STRATUS TO MOVE INTO THE SAME AREAS AS THIS MORNING. NEITHER THE NAM-BASED OR THE GFS- BASED AVIATION GUIDANCE INDICATE STRATUS FOR THE SAN ANGELO TERMINAL. HOWEVER...I DECIDED TO INCLUDE MVFR CEILINGS FOR THE SAN ANGELO TERMINAL BEGINNING AT 13Z BASED MAINLY ON PERSISTENCE. FOR OUR OTHER THREE SOUTHERN TERMINALS...THE MODELS DO INDICATE MVFR CEILINGS. SO...MY CONFIDENCE IS MUCH HIGHER FOR STRATUS RETURN TO THOSE THREE. HUBER PREV DISCUSSION... /ISSUED 533 AM CST FRI DEC 7 2012/ UPDATE... ANALYSIS OF RECENT VAD WINDS AND SODAR DATA INDICATES THAT THE WEDGE OF COOLER AIR NORTH OF THE FRONTAL BOUNDARY IS ONLY ABOUT 700 FT DEEP AS FAR NORTH AS SAN ANGELO. WITH THE BOUNDARY LOSING MOMENTUM AND STALLING...IT SHOULD NOT TAKE LONG TO MIX OUT THE COOLER AIR ACROSS THE SOUTHERN ZONES. LOW CLOUDS ARE JUST MAKING THEIR WAY INTO MASON COUNTY BUT DEWPOINTS ARE IN THE LOW/MID 60S JUST SOUTH OF I-10 /KECU AND KERV/. AS THE COLD DOME ERODES... LOW LEVEL MOISTURE WILL INCREASE AND MAY RESULT IN THE DEVELOPMENT OF A STRATO CU DECK ACROSS THE I-10 CORRIDOR AND INTO THE HEARTLAND COUNTIES. FARTHER NORTH...THIS AIRMASS IS AT LEAST 1000 FT DEEPER AND WILL BE MORE DIFFICULT TO MIX OUT TODAY. JOHNSON AVIATION... GENERALLY VFR CONDITIONS ARE ANTICIPATED THROUGH THE TAF PERIOD. THE PRIMARY EXCEPTION IS THE POTENTIAL FOR LOW CIGS FOR A FEW HOURS THIS MORNING /AND AGAIN LATE TONIGHT/ AT KJCT. HIGH CLOUDS ARE MASKING THE STRATUS ON THE SATELLITE IMAGERY BUT IT DOES APPEAR THAT THE LOW CLOUDS HAVE MADE IT INTO MASON COUNTY. OTHERWISE...EXPECT MAINLY BROKEN HIGH CLOUDS THIS MORNING BECOMING SCATTERED DURING THE DAY. WINDS WILL REMAIN LESS THAN 10 KTS WITH THE QUASI STATIONARY BOUNDARY IN THE VICINITY. NORTHWEST WINDS WILL CONTINUE AT KABI WITH SOUTH WINDS EVENTUALLY DEVELOPING AT THE OTHER FORECAST TERMINALS. JOHNSON PREV DISCUSSION... /ISSUED 340 AM CST FRI DEC 7 2012/ SHORT TERM... WE CONTINUE TO SEE STRONG QUASI ZONAL FLOW ALOFT ACROSS THE CENTRAL CONUS DOWNSTREAM OF AN OPEN...POSITIVELY TITLED TROUGH THAT IS TRAVERSING THE FOUR CORNERS. A WEAK COLD FRONT HAS MOVED INTO WEST CENTRAL TX AS FAR SOUTH OF THE I-10 CORRIDOR BUT HAS BECOME RATHER DIFFUSE AT THIS TIME GIVEN THE TYPICAL LIGHT NOCTURNAL WINDS OVER THE SOUTHERN ZONES. THE LOW STRATUS THAT IS DEVELOPING OVER THE HILL COUNTRY IS EXPECTED TO MOVE NORTH INTO THE SOUTHEAST CORNER OF THE CWA AND MAY OVERRUN THE SHALLOW FRONTAL ZONE THROUGH THE EARLY MORNING HOURS. HOWEVER...THESE CLOUDS ARE FORECAST TO ERODE BY MID/LATE MORNING. A 100 KT JET STREAK CURRENTLY EXTENDS FROM SOUTHERN NM TO MO...WITH WEAK SURFACE CYCLOGENESIS UNDERWAY IN THE RIGHT ENTRANCE REGION OVER SOUTHWEST TX. THE SOUTHERLY FLOW ON THE EASTERN FLANK SHOULD PUSH THIS BOUNDARY BACK TO THE NORTH TODAY...STALLING SOMEWHERE IN THE VICINITY OF A STERLING CITY TO BROWNWOOD LINE. TEMPS SOUTH OF THE FRONT ARE EXPECTED TO WARM INTO THE LOW TO MID 70S WHILE MID/UPPER 60S AND ANTICIPATED NORTH OF THE BOUNDARY. WINDS WILL REMAIN LESS THAN 10 MPH THROUGHOUT THE DAY AREAWIDE. THE HIGH CLOUDS ASSOCIATED WITH THE AFOREMENTIONED SUBTROPIC JET WILL ERODE DURING THE DAY...RESULTING IN PARTLY CLOUDY SKIES BY THE AFTERNOON HOURS. AS THE SUN SETS AND THE BOUNDARY LAYER COOLS...THIS QUASI STATIONARY FRONT MAY TRY TO SLIDE SOUTH BACK INTO THE CONCHO VALLEY. IT REALLY SHOULD HAVE LITTLE IMPACT OTHER THAN SERVING TO LOWER DEWPOINTS. MIN TEMPS WILL REMAIN UNSEASONABLY MILD...RANGING FROM THE LOWER 40S TO THE NEAR 50 DEGREES. THE MODELS CONTINUE TO BRING DEWPOINTS BACK INTO THE LOWER 50S ALONG THE I-10 CORRIDOR BUT THEY HAVE BEEN QUITE POOR AS OF LATE...EVEN WITH MODEL INITIALIZATIONS. ANY STRATUS AND/OR FOG SHOULD BE CONFINED TO THE SOUTHEAST QUADRANT OF THE CWA TONIGHT WITH MOSTLY CLEAR SKIES ELSEWHERE. JOHNSON LONG TERM... BY SATURDAY MORNING THE FLOW ALOFT OVER THE FORECAST AREA WILL BE ZONAL...BEGINNING TO BACK TO THE SOUTHWEST AHEAD OF AN UPPER TROUGH DIGGING SOUTH OVER THE SOUTHWESTERN STATES. WILL HAVE WARMING TEMPERATURES SATURDAY WITH AFTERNOON HIGHS WELL ABOVE SEASONAL NORMS IN THE LOWER 70S TO THE LOWER 80S UNDER MOSTLY SUNNY SKIES. AS THE UPPER TROUGH MOVES EAST ACROSS THE CWA SUNDAY IT WILL PUSH A STRONG COLD FRONT SOUTH THROUGH THE FORECAST AREA SUNDAY...EXITING OUR SOUTHERN TIER OF COUNTIES SUNDAY EVENING. MODELS ARE SHOWING SATURATED SOUNDINGS TO AROUND 500MB AFTER MIDNIGHT ON SUNDAY AND INTO MONDAY MORNING OVER THE BIG COUNTRY. HAVE INCLUDED A SLIGHT CHANCE OF LIGHT SNOW OVER THE BIG COUNTRY AFTER MIDNIGHT...ENDING AROUND MID-MORNING ON MONDAY. GIVEN WARM GROUND CONDITIONS AHEAD OF THE FRONTAL PASSAGE...NOT EXPECTING ANY SNOW ACCUMULATION WITH THIS SYSTEM. HOWEVER...WILL SEE THIS SEASONS COLDEST TEMPERATURES. MONDAY MORNING TEMPERATURES WILL RANGE FROM THE UPPER 20S TO AROUND 30 DEGREES WITH THE COLDEST MORNING TEMPERATURES ON TUESDAY...WITH LOWS IN THE LOWER 20S ACROSS THE ENTIRE FORECAST AREA. AFTERNOON HIGHS ON MONDAY WILL ONLY BE IN THE 40S WITH TUESDAY AFTERNOON HIGHS IN THE 50S. FOR THE REMAINDER OF THE WEEK WE WILL HAVE SEASONAL AFTERNOON HIGHS IN THE LOWER 60S AND CLOSE TO SEASONAL MORNING LOWS GENERALLY IN THE MID 30S. NO ADDITIONAL PRECIPITATION IS EXPECTED THROUGH THE END OF THE WEEK. && .PRELIMINARY POINT TEMPS/POPS... ABILENE 42 75 50 59 29 / 0 0 0 10 10 SAN ANGELO 43 81 51 67 31 / 0 0 0 5 10 JUNCTION 48 82 52 73 32 / 0 5 0 10 10 && .SJT WATCHES/WARNINGS/ADVISORIES... NONE. && $$ HUBER
AREA FORECAST DISCUSSION
NWS SPOKANE WA
407 PM PST Sat Dec 8 2012 .SYNOPSIS... Clearing skies tonight with a cool and dry air mass will bring frosty morning temperatures Sunday. A cool and active early winter weather pattern will bring a series of relatively weak weather systems through the upcoming week...each capable of producing relatively minor accumulations of snow. && .DISCUSSION... Quick update to the forecast, mainly to add more potential fog to the northern valleys. Surface dew point analysis shows that while the Spokane/CdA area has mid-teens dew points, the northern valleys have mid-20s dew points with some areas of clear skies. Fog should form rapidly in these areas in the next few hours. Whether it can last the night is a more difficult call. Went with patchy fog for the rest of the night and Sunday morning hours but confidence in this is low. Afternoon weather balloon showed very air above the surface, which argues against much fog or low clouds tonight. This is also drier than what the 18Z models expected. But they show a surge of low level moisture from the south later tonight in response to southerly winds ahead of the next weather system. 22Z RAP model shows the same idea. Will check out 00Z runs before I make any more changes to the forecast in this regard. Temperatures will be cold tonight. Have to adjust Deer Park downward significantly. RJ && .AVIATION... 00Z TAFS: A mean northwesterly flow over the region will continue to spread some middle and high clouds across the Inland Northwest, with some localized MVFR stratocu toward the WA/ID border. Low pressure approaching overnight into Sunday is expected to gradually turn lower level flow toward the southeast. With a modest temperatures and dew point spread around sunset Saturday evening but the potential for effective radiational cooling in the less dense middle and higher clouds brings the thought of stratus and/or fog. The lower level atmosphere is relatively dry and these features are not expected to be widespread. However all guidance is showing some moisture creeping up the Palouse toward the KGEG-KCOE area toward morning with the increase low level southeast flow. While confidence is only fair, I have added some MVFR stratus to this region for at least a brief period around Sunday morning. As the system moves in late in the day, expected thickening clouds from the west. A few flurries or a brief snow shower may develop before 00Z Monday, however the risk is slight. /J. Cote` && .PREV DISCUSSION... /ISSUED 347 PM PST Sat Dec 8 2012/ SYNOPSIS... Clearing skies tonight with a cool and dry air mass will bring frosty morning temperatures Sunday. A cool and active early winter weather pattern will bring a series of relatively weak weather systems through the upcoming week...each capable of producing relatively minor accumulations of snow. DISCUSSION... Tonight through Sunday...North/northwest flow aloft has developed over the forecast area under the eastern flank of a broad eastern Pacific ridge. Models are in good general agreement depicting a flattening of this flow to a more west/northwest direction on Sunday. Satellite imagery depicts this northerly flow but also indicates this is a rather dirty ridge with plenty of at least mid and high altitude moisture associated with the polar jet axis diving down this ridge flank. At the surface high pressure over the Canadian prairie is providing a shot of dry low level continental air into the forecast area. The combination of this dry low level air ans increasing subsidence aloft under the ridge should allow a clear and frost night to evolve with good radiational cooling conditions especially at snow covered locations. Current lingering orographic snow showers will minor out overnight. On Sunday models are in decent agreement in in transiting an weak mid level disturbance through the flow from wet to east across the forecast area during the day. A lack of dynamic support and with an anemic moisture feed in this traditionally dry flow regime will cause this wave to weaken further as it crosses the region during the day Sunday. While scattered snow showers will probably result over the northern tier high terrain...and a few flurries are possible over the northern basin...there is no compelling reason to expect any significant accumulations from this feature. Sunday will likely be another seasonably cool day of increasing clouds with most of the light precipitation threat (snow...not rain) over the northern mountains...Idaho Panhandle mountains and Cascades higher terrain. /Fugazzi Sunday night through Tuesday: A strong ridge offshore will keep a dominant northwest flow across the Inland Northwest through early next week. With the departure of the upper level trough, gradual warming will be underway as a weak warm front pushes through region late Sunday night into Monday morning. In the wake of the front, low level moisture will be difficult to scrub out and sounding profiles show the small chance of freezing drizzle in the northern valleys early Monday morning before the low clouds mix out. Meanwhile, isentropic lift coupled with orographics will bring another shot of snow to the Idaho panhandle especially for the central Panhandle mountains and the Camas Prairie, where there is the potential for snow advisory amounts Sunday night through Monday morning. Drier air will move across the region allowing the snow showers to taper off over north Idaho by Monday afternoon. This will be short lived as the next warm front reaches the region from the north late Monday night, followed by an occluded front sliding across the region on Tuesday. This will bring another good shot of snow to much of the northern and Panhandle mountains. Enough west to northwest flow will keep a rain shadow in the lee of the Cascades into the western Basin. Meanwhile a wintry mix is possible across the eastern Columbia Basin and Palouse on Tuesday morning, before the front slides through and changes precipitation types to valley rain and mountain snow by Tuesday afternoon. Temperatures will be moderating slightly above seasonal normals by Tuesday. /rfox. Tuesday night through Thursday: The Inland Northwest will remain in a northwest flow and in the path of systems dropping in from the Gulf of Alaska. An amplified and relatively strong system drops into the western United States Tuesday night and Wednesday. The brunt of the lift dives into Oregon and California, yet the Inland Northwest gets it fair share. Regional 700-500mb omega peaks at the beginning of this period between -3 to -11 microbars/second, along and ahead of the incoming cold front and upper trough axis. The strongest of this lift is directed across the southeast. This is accompanied by deep layer moisture, with PWATs peaking between 110-140% of normal. These ingredients will keep the threat of precipitation high across eastern third of Washington and Idaho, as well as the Cascade crest in the onshore flow, Tuesday evening. The focus shifts to the southeast third of Washington and central and southern Panhandle overnight into Wednesday as the cold front shifts southeast. Some drier air invades the middle to upper levels of the atmosphere. Yet an inverted surface trough/deformation axis extending from southeast Idaho to the eastern Washington will help to focus the still modest sfc-700mb moisture and continued high precipitation chances over the eastern forecast area. Wednesday night into Thursday a shortwave ridge builds in and the inverted surface trough and precipitation will gradually weaken and peter out to that by Thursday mainly light orographic snow showers linger around the Panhandle through the Blue Mountains. Milder air in advance of this system will generally favor snow levels between 2000-3500 feet along and south of the I-90 corridor Tuesday evening, while snow levels further north of here remain between valley floors and 2000 feet. This supports snow or rain/snow mix along the I-90 corridor northward and rain and mountain snow south of I-90 early Tuesday evening. However from late evening into Wednesday morning snow levels are expected to drop. The primary rain/snow threat will shift to the southeast third of Washington and lower Panhandle overnight and by Wednesday cooling aloft will bring mainly a snow threat. Temperatures warm to near freezing or a degree or two above by Wednesday afternoon, potentially limiting any accumulations. However banding under the inverted surface trough could allow for some modest snow rates and at least light accumulations, or possibly more. Between Tuesday night and Wednesday the area that may receive the most impacts from snow would be the central Panhandle, higher Palouse and southern portions of Spokane and Kootenai county. These details are apt to wobble so stay tuned; but estimating snow amounts suggest marginal snow amounts for a highlight. Thursday night and Friday: The next shortwave system comes in from the northwest. Models begin to diverge over the precise timing and track and strength, but overall this system appears weaker than the Tuesday night-Wednesday system. The frontal wave occludes and stretches on approach Thursday evening and skims by the region overnight into Friday. This will renew the threat of precipitation throughout the region. The best threat will be over the Cascades, with a secondary modest threat across the eastern third of Washington and north Idaho, with the lee of the Cascades and Basin once again finding a minimal threat. Precipitation amounts will depend on the strength of the system and this will come into better focus as models come into better agreement. However precipitation is expected to be mainly in the form of snow with the colder air brought in with the prior system. /J. Cote` Saturday and Sunday...Another in a series of troughs will swing through the Inland Northwest next weekend, with high chances for additional mountain snow and valley rain and snow. A warm front lifting north into at least the southern portions of Washington may play havoc with which areas get rain and snow or just snow. However, given this is the extended extended went with a general trend, didn`t stray far from the previous forecast, which also matched up well with our neighbors. Temperatures look to be right around mid- December normals. ty AVIATION... 00Z TAFS: A mean northwesterly flow over the region will continue to spread some middle and high clouds across the Inland Northwest, with some localized MVFR stratocu toward the WA/ID border. Low pressure approaching overnight into Sunday is expected to gradually turn lower level flow toward the southeast. With a modest temperatures and dew point spread around sunset Saturday evening but the potential for effective radiational cooling in the less dense middle and higher clouds brings the thought of stratus and/or fog. The lower level atmosphere is relatively dry and these features are not expected to be widespread. However all guidance is showing some moisture creeping up the Palouse toward the KGEG-KCOE area toward morning with the increase low level southeast flow. While confidence is only fair, I have added some MVFR stratus to this region for at least a brief period around Sunday morning. As the system moves in late in the day, expected thickening clouds from the west. A few flurries or a brief snow shower may develop before 00Z Monday, however the risk is slight. /J. Cote` && .PRELIMINARY POINT TEMPS/POPS... Spokane 18 32 24 33 28 35 / 10 10 40 10 20 60 Coeur d`Alene 16 32 23 34 29 34 / 10 20 50 20 20 60 Pullman 19 31 26 38 30 38 / 10 10 50 20 10 50 Lewiston 24 40 31 43 33 44 / 10 10 30 20 10 40 Colville 19 32 23 34 28 38 / 10 20 40 10 30 60 Sandpoint 17 33 24 31 27 35 / 10 20 70 20 50 60 Kellogg 16 28 23 32 29 33 / 10 20 80 50 40 70 Moses Lake 21 36 23 36 27 38 / 10 10 10 0 10 10 Wenatchee 24 37 25 37 27 39 / 10 10 10 10 10 10 Omak 19 32 20 34 23 34 / 10 10 10 10 10 10 && .OTX WATCHES/WARNINGS/ADVISORIES... ID...None. WA...None. && $$
AREA FORECAST DISCUSSION
NWS GREEN BAY WI
803 PM CST SAT DEC 8 2012 .UPDATE... CLEAR SKIES AND LIGHT WINDS EARLY THIS EVENING ALLOWING TEMPS TO DROP QUICKLY TO BELOW FORECAST MINS. MADE UPDATE WITH THOUGHTS THAT TEMPS WOULD REBOUND A BIT AS WINDS AND CLOUDS INCREASE THROUGH THE NIGHT. RAP HAS NOT CAUGHT UP WITH THIS TREND YET. NO CHANGES TO HEADLINES ATTM WITH SNOW NOW MOVING INTO WESTERN MN. NEW NAM JUST ARRIVING. TE && .PREV DISCUSSION...ISSUED AT 538 PM CST SAT DEC 8 2012... SYNOPSIS...SNOW TOMORROW...THEN QUIET WEATHER FOR THE START OF THE WORK WEEK. THE LARGE SCALE PATTERN ACRS NOAM WAS DOMINATED BY RIDGES NR BOTH COASTS...WITH FAIRLY BROAD TROF OVER THE MIDDLE OF THE CONTINENT. THAT GENERAL PATTERN WL CONT FOR THE FCST PERIOD...THOUGH THE TREND WL BE FOR A LITTLE MORE SPLITTING OF THE FLOW WITHIN THE BASE OF THE UPR TROF TO OCCUR DURING THE LATTER PART OF THE PERIOD. THE MAIN WX MAKERS WL BE A SERIES OF MJR SHRTWVS/CYCLONES MOVG THRU THE PATTERN. A FAIRLY SIG PCPN EVENT IS LIKELY WITH EACH CYCLONE...RESULTING IN NR NORMAL AMNTS FOR THE PERIOD. TEMPS WL LIKLEY END UP A LITTLE ABV NORMAL FOR THE PERIOD. SHORT TERM...TONIGHT AND SUNDAY. THE MAIN CONCERN DURING THIS PART OF THE FORECAST IS THE SYSTEM THAT WILL BRING SNOW TO THE AREA STARTING SUNDAY MORNING. ESPECIALLY SINCE GETTING THIS ONE WRONG COULD REFLECT POORLY ON OUR OFFICE WITH GREEN BAY IN THE NATIONAL SPOTLIGHT. A WEAK UPPER LEVEL RIDGE AND HIGH PRESSURE AT THE SURFACE WILL MOVE EAST TONIGHT AND SUNDAY. AN UPPER LEVEL SHORT WAVE IS EXPECTED TO MOVE INTO WISCONSIN DURING THE DAY ON SUNDAY. A SURFACE LOW PRESSURE SYSTEM WAS FORECAST TO WEAKEN AS IT MOVES ACROSS THE PLAINS BEFORE BEING ABSORBED BY THE LOW MOVING THROUGH ILLINOIS. THE RESULTANT PRESSURE PATTERN HAS A LOW OVER SOUTHERN LAKE MICHIGAN AT 00Z MONDAY WITH A TROUGH EXTENDING NORTHWEST INTO NORTHERN MINNESOTA. UPPER LEVEL DIVERGENCE ASSOCIATED WITH THE LEFT EXIT REGION OF A JET MAX WILL HELP ENHANCE LIFT OVER THE NORTHWEST PART OF THE FORECAST AREA DURING THE DAY ON SUNDAY. HPC WINTER WEATHER ACCUMULATIONS SHOWED AN AREA OF 4 TO 6 INCHES ACROSS PART OF NORTH CENTRAL WISCONSIN WITH 2 TO 4 INCHES COVERING THE REST OF THE AREA FOR THE 24 HOUR PERIOD ENDING AT 00Z MONDAY. THIS SEEMED PRETTY GOOD BASED ON MODEL QPF. MODEL TIMING DIFFERENCES MADE THE FORECAST FOR THE START OF THE WINTER WEATHER ADVISORY CHALLENGING. ENDED UP KEEPING 12Z FOR A START TIME IN THE WEST AND 15Z FARTHER EAST. STORM SNOWFALL TOTALS COULD REACH WARNING CRITERIA IF THE SNOW WERE TO FALL IN A 12 HOUR PERIOD...BUT THINK ACCUMULATION WOULD BE OVER A LONGER PERIOD THAN THAT. LONG TERM...SUN NGT THRU NEXT SAT. CYCLONE WL BE CROSSING THE RGN SUN NGT. UPR JET WL BE RIGHT ACRS THE AREA...SO THE SRN PART OF THE FCST AREA MAY BE AFFECTED BY UPR/MID-LVL DRY SLOT. ALTHOUGH THERMAL PROFILES WL BE COLD ENOUGH FOR SNOW...LACK OF SEEDING OF THE LOWER CLDS WITH ICE CRYSTALS WL PROBABLY LEAD TO SOME DZ/FZDZ /DEPENDING ON SFC TEMPS/ ACRS E-C AND MAYBE C WI DURING THE EVENING. THAT COULD LINGER PAST MIDNIGHT...BUT MID-LVL MOISTURE FM REMNANTS OF COMMA HEAD SHOULD SWING BACK SE ACRS THE AREA DURING THE NGT...SO KEPT PCPN LATER IN THE NGT AS SHSN. LAKE-EFFECT POTENTIAL FOR THE LAKE-SUPERIOR SNOWBELT IS SOMEWHAT MUDDLED. FLOW WL PROBABLY BECOME TOO ELY FOR A TIME. THEN THE WINDS WL SWING BACK ARND THROUGH A MORE FAVORABLE DIRECTION...BUT CONT BACKING AND PROBABLY BECOME LGT BY LATE MON. AT THIS POINT OPTED TO FOCUS THE HEADLINE ON THE SYSTEM SNOWS...AND FOREGO EXTENDING IT TO COVER THE POSSIBLE SHORT-LIVED LAKE-EFFECT EVENT MONDAY. TEMPS ALSO TRICKY. NOT ANTICIPATING THAT A LOT OF CLEARING WL BE ABLE TO OCCUR BEFORE THE SFC RIDGE WORKS INTO THE RGN. IN ADDITION...THE STRONGEST SURGE OF THE COLDER AIR FLOWING SWD IN THE WAKE OF THE DEPARTING SYSTEM WL BE S AND W OF THE FCST AREA. SO WITH THE EXPECTATION OF HAVING PLENTY OF CLDS AND ONLY WK CAA...RAISED TEMPS FOR THE NEXT SEVERAL PERIODS...ESP AT NGT. OF COURSE IF WE WERE TO SOMEHOW CLEAR OUT AND HAVE LGT WINDS WITH THE FRESH SNOW COVER...TEMPS COULD EASILY DROP 20+ F DEGREES BELOW FCST MINS. BUT THE CHC OF THAT HAPPENING JUST DOES NOT SEEM GREAT ENOUGH TO EVEN HEDGE THE FCST IN THAT DIRECTION. THE NEXT MAJOR SYSTEM HEADING NEWD OUT OF THE PLAINS WL PROBABLY ARRIVE NEXT WEEKEND. && .AVIATION...VFR CONDITIONS TO CONTINUE THROUGH THE NIGHT...WITH HIGH AND MID CLOUDS OVERTAKING THE SKY. INCOMING LOW PRESSURE WILL BRING SNOW TO THE AREA BEGINNING SUN MORN. EXPECT RAPID DETERIOATION OF CIGS AND VSBY WITH SNOW. ACCUMULATING SNOW AND GUSTY EAST WINDS EXPECTED AT ALL TAF SITES THROUGH SUN AFTN. TE && .GRB WATCHES/WARNINGS/ADVISORIES... WINTER WEATHER ADVISORY FROM 6 AM SUNDAY TO 6 AM CST MONDAY FOR WIZ005-010-011-018-019-030-035-036. WINTER WEATHER ADVISORY FROM 9 AM SUNDAY TO 6 AM CST MONDAY FOR WIZ012-013-020-021-031-037-045-073-074. && $$
AREA FORECAST DISCUSSION
NWS GRAND JUNCTION CO
1035 PM MST SAT DEC 8 2012 .UPDATE... ISSUED AT 1000 PM MST SAT DEC 8 2012 AT 10 PM DROPPED THE WARNINGS FOR ZONE 4 AND 13, THE ADVISORY FOR ZONE 5 AND ADDED A LOW END ADVISORY FOR ZONE 8 WHERE THE ROADS THROUGH GLENWOOD CANYON TO AVON APPEAR TO BE A MESS. THE COLD FRONT IS THROUGH THE I-70 CORRIDOR APPROACHING GUNNISON AND TELLURIDE AT 9PM. GOOD SNOWFALL IS OCCURRING FROM GLENWOOD CANYON TO VAIL PASS AND ALSO IN THE ROARING FORK. SNOW HAS STOPPED FROM STEAMBOAT SPRINGS NORTHWARD IN THE NEW COLD DRY AIR MASS. SNOW AMOUNTS IN THE PARK RANGE ARE 1-7 INCHES WITH COLUMBINE PASS RECEIVING 9 INCHES. WINDS GUSTED INTO THE 50-57MPH RANGE WITH THE FRONT THIS AFTERNOON BUT ARE ONLY IN THE 20S NOW. THE CENTRAL MOUNTAINS SO FAR HAVE RECEIVED GENERALLY 2-3 INCHES ON THE GRAND MESA, 4-5 INDEPENDENCE AND SCHOFIELD PASSES. SOUTHERN MTNS TRACE TO 3 INCHES. THE 00Z NAM AND THE 02Z RAP SHOW 0-1 INCHES FOR THE MOUNTAINS NORTH OF STEAMBOAT THROUGH SUNDAY. THE BEST FRONTAL FORCING AND JET SUPPORT MOVE TO THE CONTINENTAL DIVIDE AND EAST AFTER MIDNIGHT. THE NW SAN JUANS MAY GET 3-6 INCHES BUT THE SW SAN JUANS WILL BE CLOSER TO 0-2 INCHES. THE GUNNISON BASIN WILL LIKELY GET 0-1 BUT CERRO SUMMIT WILL LIKELY GET 2-5 INCHES. && .SHORT TERM...(THIS EVENING THROUGH SUNDAY NIGHT) ISSUED AT 328 PM MST SAT DEC 8 2012 A STRONG COLD FRONT AND UPPER TROUGH WILL MOVE THROUGH THE AREA TONIGHT THROUGH SUNDAY. THE BRUNT OF THE SYSTEM MOVED STEADILY INTO NW CO AND NE UT LATE THIS AFTERNOON AND WILL MARCH SOUTH THROUGHOUT THE NIGHT. A STRONG WIND BAND ALOFT WILL REMAIN OVER MUCH OF WRN CO AND ERN UT ABOVE THE SURFACE FRONT...THUS GOOD WESTERLY OROGRAPHICS ARE EXPECTED. THE WIND ADVY OVER THE CO NW PLATEAU WILL CONTINUE TIL NIGHTFALL. SATELLITE IMAGERY SHOWS INDICATIONS OF A JET MAX AND DEVELOPING SHORTWAVE TROUGH DROPPING DOWN THE WEST SIDE OF THE STORM. IT SHOULD MOVE AND CONTINUE DIGGING FROM ITS CURRENT POSITION OVER NRN NV/SE OREGON INTO UT AND THEN THE FOUR CORNERS LATER TONIGHT. THIS WILL SHIFT THE FOCUS FOR SNOWFALL TO THE SOUTHERN AND CENTRAL MOUNTAINS. THE WINTER WEATHER ADVISORY FOR THE NORTHERN CO MTNS WAS UPGRADED TO A WARNING BECAUSE OF THE OROGRAPHIC ENHANCEMENT EXPECTED. A SNOW ADVY WAS ADDED FOR MUCH OF THE CO CENTRAL AND SOUTHERN MOUNTAINS ASSOCIATED WITH THE SECONDARY TROUGH EXPECTED TO DIG IN TONIGHT. WINTER CONDITIONS SHOULD BEGIN DIMINISHING NORTH OF I-70 LATE TONIGHT AS THE FRONT MOVES SOUTH. SNOWFALL SHOULD DIMINISH SOUTH OF I-70 SUNDAY AFTERNOON AND EVENING. .LONG TERM...(MONDAY THROUGH SATURDAY) ISSUED AT 328 PM MST SAT DEC 8 2012 THE GRADIENT WILL REMAIN TIGHT THROUGH MONDAY/MONDAY NIGHT AS THE ROUGHLY NORTH-SOUTH ORIENTED JET PUSHES ANOTHER EMBEDDED COLD SHOT ACROSS THE AREA. AT 500 MB -30C AIR IS PROGGED TO MOVE SOUTH OF THE I-70 CORRIDOR MON EVENING INTO THE OVERNIGHT PERIOD. THE COMBINATION OF THE COLD AIR ALOFT FOR REDUCED STABILITY...AND STRONG OROGRAPHICS WILL PRODUCE ANOTHER ROUND OF SNOW OVER THE FAVORED NORTHERN AND CENTRAL MOUNTAINS...ESPECIALLY ALONG THE DIVIDE. THE LIMITING FACTOR WILL BE THE AVAILABILITY OF MOISTURE WITH GENERALLY LESS THAN 2 G/KG. HOWEVER AT THESE TEMPERATURES IT WILL NOT TAKE MUCH TO PRODUCE WIDESPREAD...BUT GENERALLY LIGHT SNOW ALONG THE NORTHWEST FACING SLOPES. ON THE PLUS SIDE...FORECAST SOUNDINGS DO INDICATE THAT THE DENDRITIC GROWTH REGION WILL BECOME SATURATED BY MONDAY AFTERNOON IN THE STEAMBOAT AND ASPEN AREAS...AND REMAIN SATURATED OVERNIGHT. SNOW WILL DIMINISH BY MIDDAY ON TUE...WITH TEMPERATURES BEGINNING TO MODIFY A LITTLE. THE PATTERN REMAINS PROGRESSIVE WITH A SHORTWAVE RIDGE MOVING ACROSS THE REGION TUE NIGHT INTO WED. THE FLOW BECOMES SOUTHWEST BY WED AFTERNOON AS THE NEXT LOW PRESSURE SYSTEM DIGS ALONG THE COAST. THESE PERIODS WILL BE DRY AND WARMER DUE TO WAA FROM THE SOUTHWEST. MODELS SHOW THAT THE WESTERN LOW PRESSURE SYSTEM WILL SPLIT AS IT DROPS ALONG THE COAST WED/WED NIGHT AND INTO THE GREAT BASIN ON THU. THIS SYSTEM HAS THE POTENTIAL TO FAVOR THE SOUTHERN MOUNTAINS AS THE SPLIT LOW TRACKS FROM THE GREAT BASIN EASTWARD. HOWEVER THERE IS STILL QUITE A BIT OF UNCERTAINTY. THE ECMWF SHOWS A CLOSED LOW OVER THE FOUR CORNERS EARLY FRI. THE GFS SHOWS MORE OF A TWO PRONGED OPEN DISTURBANCE WITH THE FIRST IMPULSE THU NIGHT...AND THE SECOND FRI NIGHT. THE GFS TRACK IS A LITTLE FARTHER NORTH AS WELL...WITH A SLIGHT CHANCE OF PRECIPITATION INTO SAT. TEMPERATURES SHOULD CLIMB ABOVE NORMAL WED AND THU...THEN FALL BELOW NORMAL AGAIN BEHIND THE TROUGH AXIS ON FRI AND SAT. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SUNDAY EVENING) ISSUED AT 920 PM MST SAT DEC 8 2012 AT 04Z THE COLD FRONT WAS THROUGH THE I-70 CORRIDOR AND APPROACHING HIGHWAY 50. IT WILL WORK THROUGH THE REMAINDER OF WESTERN COLORADO AND EASTERN UTAH BEFORE 12Z. SHSN HAVE BECOME ISOLATED ALONG AND NORTH OF KVEL KHDN KSBS. STILL LOW CLOUD CEILINGS LINGER WITH MTN OBSCURATIONS LIKELY THROUGH 14Z. SHSN WITH MVFR/IFR CIGS AND VSBY WILL CONTINUE FOR KEGE AND KASE THROUGH 10Z THEN IMPROVING INTO THE MORNING. KRIL WILL SEE OCCASIONAL MVFR CIGS WITH SHSN TO THE EAST OF THAT AIRPORT. KGJT AND KMTJ ARE IN VFR CONDITIONS WELL WEST OF THE ACTION. EXPECT MTN OBSCURATIONS THROUGH 15Z FOR ALL MTNS EAST OF A LINE FROM KGJT TO KCEZ. && .GJT WATCHES/WARNINGS/ADVISORIES... CO...WINTER WEATHER ADVISORY UNTIL 3 PM MST SUNDAY FOR COZ012-018-019. WINTER WEATHER ADVISORY UNTIL 8 AM MST SUNDAY FOR COZ004-008-009- 013-014-017. WINTER STORM WARNING UNTIL 8 AM MST SUNDAY FOR COZ010. UT...NONE. && $$ UPDATE...JOE SHORT TERM...CC/PF LONG TERM...EH AVIATION...JOE
AREA FORECAST DISCUSSION
NWS GRAND JUNCTION CO
1004 PM MST SAT DEC 8 2012 .UPDATE... ISSUED AT 1000 PM MST SAT DEC 8 2012 AT 10 PM DROPPED THE WARNINGS FOR ZONE 4 AND 13, THE ADVISORY FOR ZONE 5 AND ADDED A LOW END ADVISORY FOR ZONE 8 WHERE THE ROADS THROUGH GLENWOOD CANYON TO AVON APPEAR TO BE A MESS. THE COLD FRONT IS THROUGH THE I-70 CORRIDOR APPROACHING GUNNISON AND TELLURIDE AT 9PM. GOOD SNOWFALL IS OCCURRING FROM GLENWOOD CANYON TO VAIL PASS AND ALSO IN THE ROARING FORK. SNOW HAS STOPPED FROM STEAMBOAT SPRINGS NORTHWARD IN THE NEW COLD DRY AIR MASS. SNOW AMOUNTS IN THE PARK RANGE ARE 1-7 INCHES WITH COLUMBINE PASS RECEIVING 9 INCHES. WINDS GUSTED INTO THE 50-57MPH RANGE WITH THE FRONT THIS AFTERNOON BUT ARE ONLY IN THE 20S NOW. THE CENTRAL MOUNTAINS SO FAR HAVE RECEIVED GENERALLY 2-3 INCHES ON THE GRAND MESA, 4-5 INDEPENDENCE AND SCHOFIELD PASSES. SOUTHERN MTNS TRACE TO 3 INCHES. THE 00Z NAM AND THE 02Z RAP SHOW 0-1 INCHES FOR THE MOUNTAINS NORTH OF STEAMBOAT THROUGH SUNDAY. THE BEST FRONTAL FORCING AND JET SUPPORT MOVE TO THE CONTINENTAL DIVIDE AND EAST AFTER MIDNIGHT. THE NW SAN JUANS MAY GET 3-6 INCHES BUT THE SW SAN JUANS WILL BE CLOSER TO 0-2 INCHES. THE GUNNISON BASIN WILL LIKELY GET 0-1 BUT CERRO SUMMIT WILL LIKELY GET 2-5 INCHES. STILL CONTEMPLATING HOW TO HANDLE THE STRONG-LEANING HIGHLIGHTS THAT ARE CURRENTLY IN EFFECT. COORDINATED WITH CYS TO LOWER THE WARNING OVER ZONE 4. ZONE 5 STEAMBOAT ALSO SEEMS TO BE DONE WITH SIGNIFICANT SNOW ACCUMULATION. && .SHORT TERM...(THIS EVENING THROUGH SUNDAY NIGHT) ISSUED AT 328 PM MST SAT DEC 8 2012 A STRONG COLD FRONT AND UPPER TROUGH WILL MOVE THROUGH THE AREA TONIGHT THROUGH SUNDAY. THE BRUNT OF THE SYSTEM MOVED STEADILY INTO NW CO AND NE UT LATE THIS AFTERNOON AND WILL MARCH SOUTH THROUGHOUT THE NIGHT. A STRONG WIND BAND ALOFT WILL REMAIN OVER MUCH OF WRN CO AND ERN UT ABOVE THE SURFACE FRONT...THUS GOOD WESTERLY OROGRAPHICS ARE EXPECTED. THE WIND ADVY OVER THE CO NW PLATEAU WILL CONTINUE TIL NIGHTFALL. SATELLITE IMAGERY SHOWS INDICATIONS OF A JET MAX AND DEVELOPING SHORTWAVE TROUGH DROPPING DOWN THE WEST SIDE OF THE STORM. IT SHOULD MOVE AND CONTINUE DIGGING FROM ITS CURRENT POSITION OVER NRN NV/SE OREGON INTO UT AND THEN THE FOUR CORNERS LATER TONIGHT. THIS WILL SHIFT THE FOCUS FOR SNOWFALL TO THE SOUTHERN AND CENTRAL MOUNTAINS. THE WINTER WEATHER ADVISORY FOR THE NORTHERN CO MTNS WAS UPGRADED TO A WARNING BECAUSE OF THE OROGRAPHIC ENHANCEMENT EXPECTED. A SNOW ADVY WAS ADDED FOR MUCH OF THE CO CENTRAL AND SOUTHERN MOUNTAINS ASSOCIATED WITH THE SECONDARY TROUGH EXPECTED TO DIG IN TONIGHT. WINTER CONDITIONS SHOULD BEGIN DIMINISHING NORTH OF I-70 LATE TONIGHT AS THE FRONT MOVES SOUTH. SNOWFALL SHOULD DIMINISH SOUTH OF I-70 SUNDAY AFTERNOON AND EVENING. .LONG TERM...(MONDAY THROUGH SATURDAY) ISSUED AT 328 PM MST SAT DEC 8 2012 THE GRADIENT WILL REMAIN TIGHT THROUGH MONDAY/MONDAY NIGHT AS THE ROUGHLY NORTH-SOUTH ORIENTED JET PUSHES ANOTHER EMBEDDED COLD SHOT ACROSS THE AREA. AT 500 MB -30C AIR IS PROGGED TO MOVE SOUTH OF THE I-70 CORRIDOR MON EVENING INTO THE OVERNIGHT PERIOD. THE COMBINATION OF THE COLD AIR ALOFT FOR REDUCED STABILITY...AND STRONG OROGRAPHICS WILL PRODUCE ANOTHER ROUND OF SNOW OVER THE FAVORED NORTHERN AND CENTRAL MOUNTAINS...ESPECIALLY ALONG THE DIVIDE. THE LIMITING FACTOR WILL BE THE AVAILABILITY OF MOISTURE WITH GENERALLY LESS THAN 2 G/KG. HOWEVER AT THESE TEMPERATURES IT WILL NOT TAKE MUCH TO PRODUCE WIDESPREAD...BUT GENERALLY LIGHT SNOW ALONG THE NORTHWEST FACING SLOPES. ON THE PLUS SIDE...FORECAST SOUNDINGS DO INDICATE THAT THE DENDRITIC GROWTH REGION WILL BECOME SATURATED BY MONDAY AFTERNOON IN THE STEAMBOAT AND ASPEN AREAS...AND REMAIN SATURATED OVERNIGHT. SNOW WILL DIMINISH BY MIDDAY ON TUE...WITH TEMPERATURES BEGINNING TO MODIFY A LITTLE. THE PATTERN REMAINS PROGRESSIVE WITH A SHORTWAVE RIDGE MOVING ACROSS THE REGION TUE NIGHT INTO WED. THE FLOW BECOMES SOUTHWEST BY WED AFTERNOON AS THE NEXT LOW PRESSURE SYSTEM DIGS ALONG THE COAST. THESE PERIODS WILL BE DRY AND WARMER DUE TO WAA FROM THE SOUTHWEST. MODELS SHOW THAT THE WESTERN LOW PRESSURE SYSTEM WILL SPLIT AS IT DROPS ALONG THE COAST WED/WED NIGHT AND INTO THE GREAT BASIN ON THU. THIS SYSTEM HAS THE POTENTIAL TO FAVOR THE SOUTHERN MOUNTAINS AS THE SPLIT LOW TRACKS FROM THE GREAT BASIN EASTWARD. HOWEVER THERE IS STILL QUITE A BIT OF UNCERTAINTY. THE ECMWF SHOWS A CLOSED LOW OVER THE FOUR CORNERS EARLY FRI. THE GFS SHOWS MORE OF A TWO PRONGED OPEN DISTURBANCE WITH THE FIRST IMPULSE THU NIGHT...AND THE SECOND FRI NIGHT. THE GFS TRACK IS A LITTLE FARTHER NORTH AS WELL...WITH A SLIGHT CHANCE OF PRECIPITATION INTO SAT. TEMPERATURES SHOULD CLIMB ABOVE NORMAL WED AND THU...THEN FALL BELOW NORMAL AGAIN BEHIND THE TROUGH AXIS ON FRI AND SAT. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SUNDAY EVENING) ISSUED AT 920 PM MST SAT DEC 8 2012 AT 04Z THE COLD FRONT WAS THROUGH THE I-70 CORRIDOR AND APPROACHING HIGHWAY 50. IT WILL WORK THROUGH THE REMAINDER OF WESTERN COLORADO AND EASTERN UTAH BEFORE 12Z. SHSN HAVE BECOME ISOLATED ALONG AND NORTH OF KVEL KHDN KSBS. STILL LOW CLOUD CEILINGS LINGER WITH MTN OBSCURATIONS LIKELY THROUGH 14Z. SHSN WITH MVFR/IFR CIGS AND VSBY WILL CONTINUE FOR KEGE AND KASE THROUGH 10Z THEN IMPROVING INTO THE MORNING. KRIL WILL SEE OCCASIONAL MVFR CIGS WITH SHSN TO THE EAST OF THAT AIRPORT. KGJT AND KMTJ ARE IN VFR CONDITIONS WELL WEST OF THE ACTION. EXPECT MTN OBSCURATIONS THROUGH 15Z FOR ALL MTNS EAST OF A LINE FROM KGJT TO KCEZ. && .GJT WATCHES/WARNINGS/ADVISORIES... CO...WINTER WEATHER ADVISORY UNTIL 3 PM MST SUNDAY FOR COZ012-018-019. WINTER WEATHER ADVISORY UNTIL 8 AM MST SUNDAY FOR COZ004-008-009- 013-014-017. WINTER STORM WARNING UNTIL 8 AM MST SUNDAY FOR COZ010. UT...NONE. && $$ UPDATE...JOE SHORT TERM...CC/PF LONG TERM...EH AVIATION...JOE
AREA FORECAST DISCUSSION
NWS GRAND JUNCTION CO
921 PM MST SAT DEC 8 2012 .UPDATE... ISSUED AT 920 PM MST SAT DEC 8 2012 THE COLD FRONT IS THROUGH THE I-70 CORRIDOR APPROACHING GUNNISON AND TELLURIDE AT 9PM. GOOD SNOWFALL IS OCCURRING FROM GLENWOOD CANYON TO VAIL PASS AND ALSO IN THE ROARING FORK. SNOW HAS STOPPED FROM STEAMBOAT SPRINGS NORTHWARD IN THE NEW COLD DRY AIR MASS. SNOW AMOUNTS IN THE PARK RANGE ARE 1-7 INCHES WITH COLUMBINE PASS RECEIVING 9 INCHES. WINDS GUSTED INTO THE 50-57MPH RANGE WITH THE FRONT THIS AFTERNOON BUT ARE ONLY IN THE 20S NOW. THE CENTRAL MOUNTAINS SO FAR HAVE RECEIVED GENERALLY 2-3 INCHES ON THE GRAND MESA, 4-5 INDEPENDENCE AND SCHOFIELD PASSES. SOUTHERN MTNS TRACE TO 3 INCHES. THE 00Z NAM AND THE 02Z RAP SHOW 0-1 INCHES FOR THE MOUNTAINS NORTH OF STEAMBOAT THROUGH SUNDAY. THE BEST FRONTAL FORCING AND JET SUPPORT MOVE TO THE CONTINENTAL DIVIDE AND EAST AFTER MIDNIGHT. THE NW SAN JUANS MAY GET 3-6 INCHES BUT THE SW SAN JUANS WILL BE CLOSER TO 0-2 INCHES. THE GUNNISON BASIN WILL LIKELY GET 0-1 BUT CERRO SUMMIT WILL LIKELY GET 2-5 INCHES. STILL CONTEMPLATING HOW TO HANDLE THE STRONG-LEANING HIGHLIGHTS THAT ARE CURRENTLY IN EFFECT. COORDINATED WITH CYS TO LOWER THE WARNING OVER ZONE 4. ZONE 5 STEAMBOAT ALSO SEEMS TO BE DONE WITH SIGNIFICANT SNOW ACCUMULATION. && .SHORT TERM...(THIS EVENING THROUGH SUNDAY NIGHT) ISSUED AT 328 PM MST SAT DEC 8 2012 A STRONG COLD FRONT AND UPPER TROUGH WILL MOVE THROUGH THE AREA TONIGHT THROUGH SUNDAY. THE BRUNT OF THE SYSTEM MOVED STEADILY INTO NW CO AND NE UT LATE THIS AFTERNOON AND WILL MARCH SOUTH THROUGHOUT THE NIGHT. A STRONG WIND BAND ALOFT WILL REMAIN OVER MUCH OF WRN CO AND ERN UT ABOVE THE SURFACE FRONT...THUS GOOD WESTERLY OROGRAPHICS ARE EXPECTED. THE WIND ADVY OVER THE CO NW PLATEAU WILL CONTINUE TIL NIGHTFALL. SATELLITE IMAGERY SHOWS INDICATIONS OF A JET MAX AND DEVELOPING SHORTWAVE TROUGH DROPPING DOWN THE WEST SIDE OF THE STORM. IT SHOULD MOVE AND CONTINUE DIGGING FROM ITS CURRENT POSITION OVER NRN NV/SE OREGON INTO UT AND THEN THE FOUR CORNERS LATER TONIGHT. THIS WILL SHIFT THE FOCUS FOR SNOWFALL TO THE SOUTHERN AND CENTRAL MOUNTAINS. THE WINTER WEATHER ADVISORY FOR THE NORTHERN CO MTNS WAS UPGRADED TO A WARNING BECAUSE OF THE OROGRAPHIC ENHANCEMENT EXPECTED. A SNOW ADVY WAS ADDED FOR MUCH OF THE CO CENTRAL AND SOUTHERN MOUNTAINS ASSOCIATED WITH THE SECONDARY TROUGH EXPECTED TO DIG IN TONIGHT. WINTER CONDITIONS SHOULD BEGIN DIMINISHING NORTH OF I-70 LATE TONIGHT AS THE FRONT MOVES SOUTH. SNOWFALL SHOULD DIMINISH SOUTH OF I-70 SUNDAY AFTERNOON AND EVENING. .LONG TERM...(MONDAY THROUGH SATURDAY) ISSUED AT 328 PM MST SAT DEC 8 2012 THE GRADIENT WILL REMAIN TIGHT THROUGH MONDAY/MONDAY NIGHT AS THE ROUGHLY NORTH-SOUTH ORIENTED JET PUSHES ANOTHER EMBEDDED COLD SHOT ACROSS THE AREA. AT 500 MB -30C AIR IS PROGGED TO MOVE SOUTH OF THE I-70 CORRIDOR MON EVENING INTO THE OVERNIGHT PERIOD. THE COMBINATION OF THE COLD AIR ALOFT FOR REDUCED STABILITY...AND STRONG OROGRAPHICS WILL PRODUCE ANOTHER ROUND OF SNOW OVER THE FAVORED NORTHERN AND CENTRAL MOUNTAINS...ESPECIALLY ALONG THE DIVIDE. THE LIMITING FACTOR WILL BE THE AVAILABILITY OF MOISTURE WITH GENERALLY LESS THAN 2 G/KG. HOWEVER AT THESE TEMPERATURES IT WILL NOT TAKE MUCH TO PRODUCE WIDESPREAD...BUT GENERALLY LIGHT SNOW ALONG THE NORTHWEST FACING SLOPES. ON THE PLUS SIDE...FORECAST SOUNDINGS DO INDICATE THAT THE DENDRITIC GROWTH REGION WILL BECOME SATURATED BY MONDAY AFTERNOON IN THE STEAMBOAT AND ASPEN AREAS...AND REMAIN SATURATED OVERNIGHT. SNOW WILL DIMINISH BY MIDDAY ON TUE...WITH TEMPERATURES BEGINNING TO MODIFY A LITTLE. THE PATTERN REMAINS PROGRESSIVE WITH A SHORTWAVE RIDGE MOVING ACROSS THE REGION TUE NIGHT INTO WED. THE FLOW BECOMES SOUTHWEST BY WED AFTERNOON AS THE NEXT LOW PRESSURE SYSTEM DIGS ALONG THE COAST. THESE PERIODS WILL BE DRY AND WARMER DUE TO WAA FROM THE SOUTHWEST. MODELS SHOW THAT THE WESTERN LOW PRESSURE SYSTEM WILL SPLIT AS IT DROPS ALONG THE COAST WED/WED NIGHT AND INTO THE GREAT BASIN ON THU. THIS SYSTEM HAS THE POTENTIAL TO FAVOR THE SOUTHERN MOUNTAINS AS THE SPLIT LOW TRACKS FROM THE GREAT BASIN EASTWARD. HOWEVER THERE IS STILL QUITE A BIT OF UNCERTAINTY. THE ECMWF SHOWS A CLOSED LOW OVER THE FOUR CORNERS EARLY FRI. THE GFS SHOWS MORE OF A TWO PRONGED OPEN DISTURBANCE WITH THE FIRST IMPULSE THU NIGHT...AND THE SECOND FRI NIGHT. THE GFS TRACK IS A LITTLE FARTHER NORTH AS WELL...WITH A SLIGHT CHANCE OF PRECIPITATION INTO SAT. TEMPERATURES SHOULD CLIMB ABOVE NORMAL WED AND THU...THEN FALL BELOW NORMAL AGAIN BEHIND THE TROUGH AXIS ON FRI AND SAT. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SUNDAY EVENING) ISSUED AT 920 PM MST SAT DEC 8 2012 AT 04Z THE COLD FRONT WAS THROUGH THE I-70 CORRIDOR AND APPROACHING HIGHWAY 50. IT WILL WORK THROUGH THE REMAINDER OF WESTERN COLORADO AND EASTERN UTAH BEFORE 12Z. SHSN HAVE BECOME ISOLATED ALONG AND NORTH OF KVEL KHDN KSBS. STILL LOW CLOUD CEILINGS LINGER WITH MTN OBSCURATIONS LIKELY THROUGH 14Z. SHSN WITH MVFR/IFR CIGS AND VSBY WILL CONTINUE FOR KEGE AND KASE THROUGH 10Z THEN IMPROVING INTO THE MORNING. KRIL WILL SEE OCCASIONAL MVFR CIGS WITH SHSN TO THE EAST OF THAT AIRPORT. KGJT AND KMTJ ARE IN VFR CONDITIONS WELL WEST OF THE ACTION. EXPECT MTN OBSCURATIONS THROUGH 15Z FOR ALL MTNS EAST OF A LINE FROM KGJT TO KCEZ. && .GJT WATCHES/WARNINGS/ADVISORIES... CO...WINTER WEATHER ADVISORY UNTIL 3 PM MST SUNDAY FOR COZ012-018-019. WINTER WEATHER ADVISORY UNTIL 8 AM MST SUNDAY FOR COZ009-014-017. WINTER STORM WARNING UNTIL 8 AM MST SUNDAY FOR COZ004-010-013. WINTER WEATHER ADVISORY UNTIL MIDNIGHT MST TONIGHT FOR COZ005. UT...NONE. && $$ UPDATE...JOE SHORT TERM...CC/PF LONG TERM...EH AVIATION...JOE
AREA FORECAST DISCUSSION
NWS DES MOINES IA
1138 PM CST SAT DEC 8 2012 .UPDATE... ADDED 06Z TAF DISCUSSION. NO BIG CHANGES WITH EVENING UPDATE BUT HAVE NUDGED UP THE SNOW AMOUNTS NE IN THE MASON CITY AND WATERLOO AREAS. SMALL AREA OF PRECIP THAT MOVED THROUGH CENTRAL IA RECENTLY WAS MAINLY RAIN AT THE AIRPORT...BUT PRIMARILY SNOW JUST TO THE NORTH HERE AT THE OFFICE...AT BOONE AND AMES. MAINLY MELTED BUT JUST STUCK A LITTLE IN SOME AREAS. EXPECT THIS TO CONTINUE AS IT WORKS NE LATER TONIGHT AS 02Z RAP 2.5KM LAYER MAX WET BULB TEMP CHANGES LITTLE OVERNIGHT. THIS SUGGESTS CURRENT SNOW AND RAIN/SNOW LINES ARE A TAD TOO FAR NORTH AND HAVE SHIFTED THEM A BIT SOUTHWARD RESULTING IN A HALF INCH OR MORE INCREASE IN SNOW AMOUNTS THERE. LATEST NAM...DEV HRRR AND WRF RUNS ALL SUGGEST LOBE OF FORCING CURRENTLY PRODUCING PRECIP FROM SW MN INTO IA WILL FURTHER SATURATE AND THEN PHASE WITH MATURING SERN IA PRECIP WITH MORE WIDESPREAD COVERAGE OVER NERN IA TOWARD DAYBREAK. && .SHORT TERM /TONIGHT/... BAND OF STRONG THETA-E ADVECTION IS MOVING INTO WESTERN IOWA THIS AFTERNOON AND WILL CONTINUE TO MOVE ACROSS THE STATE THIS EVENING. RADAR ECHOES HAVE BEEN INTENSIFYING WITH THIS MID LEVEL FORCING FROM SOUTHWEST IOWA THROUGH SOUTHEAST SOUTH DAKOTA AND AT THIS TIME...ONLY PRECIPITATION REPORTS ARE FROM THE NORTHERN EDGE WITH CLOUD HEIGHTS REMAINING AOA 7KFT FARTHER SOUTH. EXPECT SOME LIGHT PRECIPITATION TO FALL OVER THE NORTHWEST THIRD TO HALF THIS EVENING ALONG THE INITIAL MOISTURE SURGE. SOME OF THIS PRECIPITATION COULD BE LIGHT SNOW GIVEN WETBULB PROFILES AS FAR SOUTH AS HIGHWAY 30 THOUGH NO ACCUMULATIONS ARE EXPECTED THIS EVENING EXCEPT FOR POSSIBLY THE FAR NORTH. A SECONDARY THETA-E SURGE WILL FOLLOW AFTER MIDNIGHT. THIS WILL HELP KEEP LOW LEVEL TEMPERATURES ABOVE FREEZING OVER THE CENTRAL AND SOUTH AND KEEP WETBULBS IN THE LOWEST 1500-2500FT 34F OR HIGHER. THIS LAYER WILL BE ENOUGH TO MELT ANY SNOW THROUGH THIS REGION. COLDER PROFILES YET NORTH WHERE PRECIPITATION WILL BE EXPANDING WITH THE ARRIVAL OF INCREASING KINEMATICS WITH THE APPROACH OF THE UPPER LEVEL SHORT WAVE. THE PRECIPITATION WILL BE ALL SNOW OVER THE NORTH. EXPECT SEASONAL TO SLIGHTLY HIGHER SNOW RATIOS OVER THE NORTH OF 13-15 TO 1 AND COULD HAVE ACCUMULATIONS BY 12Z OF 0.5 TO 1.5 INCHES ALONG AND NORTH OF A DENISON TO FORT DODGE TO WAVERLY LINE. NON-DIURNAL TEMPERATURE TRENDS OVERNIGHT WITH HIGHER DEWPOINTS MOVING INTO THE STATE. .LONG TERM /SUNDAY THROUGH FRIDAY/... THERE ARE TWO SYSTEMS TO FOCUS ON IN THE EXTENDED. THE FIRST IS THE SYSTEM FROM TONIGHT THAT WILL BE QUICKLY PUSHING ACROSS THE CWA DURING THE MORNING HOURS FOLLOWED BY STRONG COLD ADVECTION. SOUNDINGS AT 12Z SHOW TEMPERATURES AT OR JUST ABOVE FREEZING ACROSS THE FORECAST AREA. A COLD FRONT WILL SWEEP THE CWA THROUGH THE MORNING AND SOUNDING LOCATIONS WEST OF I-35 DRY OUT BEHIND THE FRONT WITH TEMPERATURES FALLING THROUGHOUT THE LATE MORNING AND THE REST OF THE DAY. FORCING WEAKENS THROUGHOUT THE DAY BUT POCKETS OF BETTER FORCING REMAIN ACROSS CENTRAL IOWA THROUGH MOST OF THE DAY. THE PROBLEM IS THAT WE LOSE OUR DEEPER MOISTURE QUICKLY IN THE MORNING. AS A RESULT...I AM NOT LOOKING FOR MUCH IN THE WAY OF PRECIPITATION/SNOW ACCUMULATION OUT OF THIS SYSTEM. WE COULD SEE A COUPLE OF INCHES ACROSS THE NORTH AT BEST WITH TRACE AMOUNTS ELSEWHERE AS PRECIP TRANSITIONS TO SNOW BEFORE ENDING. THE SURFACE LOW IS TOO FAR NORTH AND THE UPPER WAVE IS NOT DEEP ENOUGH TO DO MUCH MORE THAN THAT. WINDS ON THE OTHER HAND MAY BE PROBLEMATIC SUNDAY...ESPECIALLY COMBINED WITH THE COLD AIR MOVING IN. WIND CHILLS WILL FALL INTO THE TEENS DURING THE AFTERNOON. TUESDAY THROUGH THURSDAY...THERE WILL BE A LONG WAVE TROUGH PASSING ACROSS THE REGION WITH A RIDGE BUILDING INTO THE WEST TUESDAY AND SHIFTING ACROSS THE MIDWEST THROUGH THURSDAY AS A LARGE TROUGH CARVES OUT OVER THE WEST. THIS WILL BE A PLAYER IN OUR WEATHER INTO THE WEEKEND. THEN LATER IN THE WEEK...IN THE FRIDAY TO SATURDAY NIGHT TIME FRAME A SECOND POTENTIALLY STRONG SYSTEM WILL AFFECT CENTRAL IOWA. THERE ARE SIGNIFICANT DIFFERENCES BETWEEN THE MODELS...AT LEAST INITIALLY AS TO THE EVOLUTION OF THE UPPER LEVEL WAVE...THE SURFACE LOW AND THE FRONTAL BOUNDARY WITH THE SYSTEM. THE GFS LEAVES THIS AN OPEN WAVE THROUGH FRIDAY THEN DEVELOPS A LOW OVER SOUTH DAKOTA AS THE SYSTEM WRAPS UP WHILE THE EURO DEVELOPS A DEEP LOW OVER KANSAS AND LIFTS IT NORTHEAST. BOTH MODELS PUT THE UPPER LOW OVER SE MN AT 00Z BUT HOW IT GETS THERE IS AN QUESTION. THE EURO DEVELOPS A MUCH BETTER DEFORMATION ZONE OVER NORTHERN INTO WEST CENTRAL IOWA WHILE THE GFS HAS THIS FURTHER NORTH. THE SURFACE LOW POSITION IS ALSO QUITE DIFFERENT IN PLACEMENT AND INTENSITY. BOTH MODELS POINT AT SOUTHERN IOWA AND LOCATIONS SOUTH AND EAST BEING IN A WARM ADVECTION ZONE WITH PRETTY IMPRESSIVE CAPE FOR MID DECEMBER. THEREFORE I HAD TO PUT IN ISOLATED THUNDER ACROSS THE SOUTH. PTYPE ELSEWHERE IS VERY DIFFICULT TO PINPOINT AT THIS POINT. THE NORTH INTO WEST CENTRAL COULD HAVE A MIXED BAG OF PRECIP CHANGING TO SNOW AND ACCUMULATING. A RAIN/SNOW TRANSITION WILL OCCUR BETWEEN THERE AND SOUTH BUT THERE IS NOT ENOUGH AGREEMENT BETWEEN THE MODELS TO SAY WITH ANY CERTAINTY. AT THIS POINT IT LOOKS MESSY WITH A POTENTIAL FOR SEVERAL PTYPES ACROSS IOWA AND THUNDER SOUTH. HOWEVER THE MODELS DID SOMETHING SIMILAR WITH THIS CURRENT SYSTEM AT THAT FAR OUT. && .AVIATION...09/06Z CONDITIONS HAVE DETERIORATED THIS EVENING AND NOW MAINLY VARY FROM LIFR-MVFR. ALTHOUGH PATCHY LIGHT PRECIP WILL CONTINUE JUST AFTER MIDNIGHT ADDITIONAL PRECIP IS EXPECTED DEVELOP AFTER 09Z IN KMCW/KALO AREA...MAINLY IN THE FORM OF SNOW. ONCE THIS OCCURS MANY LOCATIONS WILL LIKELY DIP TO LIFR OR AT LEAST IFR. PRECIP SHOULD END 14-16Z FOLLOWED BY WINDS BECOMING NW WITH GUSTS INTO THE 20S INTO THE AFTERNOON AND EVENING. && .DMX WATCHES/WARNINGS/ADVISORIES...NONE. && $$ UPDATE/AVIATION...SMALL SHORT TERM...DONAVON LONG TERM...FAB
AREA FORECAST DISCUSSION
NWS WICHITA KS
329 AM CST SUN DEC 9 2012 .DISCUSSION... TODAY-THIS EVENING: THE GUSTY NORTHWEST WINDS AND COLDEST AIR IS LAGGING BEHIND THE INITIAL WIND SHIFT. PRECIPITATION SO FAR HAS BEEN EXTREMELY LIMITED AND BASED ON LATEST MODEL RUNS...LOW LEVEL DRY AIR WILL LIKELY BE TOUGH TO OVERCOME. HOWEVER BEST SATURATION/LIFT IN TRAILING BAND FAIRLY IMPRESSIVE...BUT SO IS THE 10KFT OF DRY AIR BELOW IT. WHILE LIGHT SNOW IS LIKELY ALOFT...BELIEVE IT WILL BE VERY DIFFICULT TO GET MORE THAN SCATTERED FLURRIES TO THE GROUND. MID/UPPER LEVEL LIFT ACTUALLY INCREASES A BIT TOWARDS 0000 UTC...AND WILL LINGER FLURRIES UNTIL MIDNIGHT ACROSS EASTERN SECTIONS. TEMPERATURES WILL GENERALLY FALL THROUGHOUT THE DAY WITH COLD AIR ADVECTION FROM THE GUSTY NORTHWEST WINDS. LATE TONIGHT: TEMPERATURES WILL CONTINUE TO TUMBLE DURING THE NIGHT WITH CLEARING SKIES AND DECREASING WINDS. MODEL OUTPUT STATISTICS GUIDANCE IN GOOD AGREEMENT FOR SINGLE DIGITS FOR FAR NORTHWEST SECTIONS. MON-SAT: AFTER VERY CHILLY START TO MONDAY...EXPECT A GRADUAL MODERATION OF THE COLD AIRMASS. SHORTWAVE MOVING THROUGH MIDWEEK STILL APPEARS TO BE MOISTURE STARVED WITH ONLY SOME INCREASE IN CLOUDS. DECENT WARMUP ANTICIPATED WITH COMBINATION OF DRY AIR AND FAVORABLE SW FLOW AT H85 ON THU. MODELS HAVE DIVERGED WITH TRACK/TIMING OF SYSTEM LATE IN THE WEEK. UNFORTUNATELY...OVERALL TREND HAS LOWER CHANCES FOR PRECIPITATION ACROSS WESTERN HALF OF FORECAST AREA AS SURFACE CYCLOGENSIS DEVELOPS DRY SLOT OVER MUCH OF THE FORECAST AREA. BEST CHANCE STILL APPEARS TO BE IN SOUTHEAST KS. -HOWERTON && .AVIATION...06Z TAFS KRSL/KSLN/KHUT/KICT/KCNU LOW LEVEL ISENTROPIC LIFT FROM THE SOUTH-SOUTHWEST HAS LED TO WIDESPREAD IFR CONDITIONS ACROSS THE REGION LATE THIS EVENING. BOTH THE NAM/WRF AND GFS NOT HANDLING THIS LOW LEVEL MOISTURE VERY WELL...WITH THE LATEST RUC40 CLOSER TO REALITY. THE CEILINGS EVEN DROPPED LOWER THAN THE PESSIMISTIC RUC ON CEILINGS TO AROUND 6-9K FT AGL. EXPECT THE IFR CONDITIONS TO BE SHORT LIVED...AS A COLD FRONTAL BOUNDARY LOOKS TO ARRIVE AFTER 08Z-09/SUN ACROSS CENTRAL KANSAS...AND PLUNGE SOUTH ACROSS SOUTH CENTRAL KS AFTER 09-11Z/SUN. THIS WILL LEAD TO CEILINGS BEGINNING TO RAPIDLY LIFT WITH MVFR/VFR CEILINGS RETURNING BY THE MORNING HOURS ON SUN...AS LOW LEVELS QUICKLY DRY OUT. WINDS BEHIND THE FRONT WILL INCREASE TO 20-30 KTS WITH SOME LIGHT SNOW DEVELOPING ACROSS PORTIONS OF CENTRAL KANSAS EARLY SUNDAY. NOT EXPECTING THE LIGHT SNOW TO RESTRICT VSBYS MUCH WITH VFR CONDITIONS EXPECTED...AS THIS WILL BE MAINLY A LIGHT SNOW/FLURRY EVENT. KETCHAM && .PRELIMINARY POINT TEMPS/POPS... WICHITA-KICT 38 13 37 19 / 10 10 0 0 HUTCHINSON 35 11 37 21 / 10 10 0 0 NEWTON 35 12 35 20 / 10 10 0 0 ELDORADO 38 13 35 18 / 10 10 0 0 WINFIELD-KWLD 41 14 37 21 / 10 10 0 0 RUSSELL 33 4 37 19 / 10 0 0 0 GREAT BEND 33 7 37 22 / 20 0 0 0 SALINA 35 10 37 20 / 10 10 0 0 MCPHERSON 34 11 37 20 / 10 10 0 0 COFFEYVILLE 46 20 36 19 / 20 10 0 0 CHANUTE 43 16 34 18 / 20 10 0 0 IOLA 42 16 34 20 / 20 10 0 0 PARSONS-KPPF 44 17 35 16 / 20 10 0 0 && .ICT WATCHES/WARNINGS/ADVISORIES... NONE. && $$
AREA FORECAST DISCUSSION
NWS WICHITA KS
1139 PM CST SAT DEC 8 2012 .AVIATION...06Z TAFS KRSL/KSLN/KHUT/KICT/KCNU LOW LEVEL ISENTROPIC LIFT FROM THE SOUTH-SOUTHWEST HAS LED TO WIDESPREAD IFR CONDITIONS ACROSS THE REGION LATE THIS EVENING. BOTH THE NAM/WRF AND GFS NOT HANDLING THIS LOW LEVEL MOISTURE VERY WELL...WITH THE LATEST RUC40 CLOSER TO REALITY. THE CEILINGS EVEN DROPPED LOWER THAN THE PESSIMISTIC RUC ON CEILINGS TO AROUND 6-9K FT AGL. EXPECT THE IFR CONDITIONS TO BE SHORT LIVED...AS A COLD FRONTAL BOUNDARY LOOKS TO ARRIVE AFTER 08Z-09/SUN ACROSS CENTRAL KANSAS...AND PLUNGE SOUTH ACROSS SOUTH CENTRAL KS AFTER 09-11Z/SUN. THIS WILL LEAD TO CEILINGS BEGINNING TO RAPIDLY LIFT WITH MVFR/VFR CEILINGS RETURNING BY THE MORNING HOURS ON SUN...AS LOW LEVELS QUICKLY DRY OUT. WINDS BEHIND THE FRONT WILL INCREASE TO 20-30 KTS WITH SOME LIGHT SNOW DEVELOPING ACROSS PORTIONS OF CENTRAL KANSAS EARLY SUNDAY. NOT EXPECTING THE LIGHT SNOW TO RESTRICT VSBYS MUCH WITH VFR CONDITIONS EXPECTED...AS THIS WILL BE MAINLY A LIGHT SNOW/FLURRY EVENT. KETCHAM && .PREV DISCUSSION... /ISSUED 926 PM CST SAT DEC 8 2012/ UPDATE... LOW CLOUDS AND DRIZZLE HAVE OVERSPREAD MUCH OF CENTRAL AND SOUTH CENTRAL KS THIS EVENING...AS ISENTROPIC LIFT CONTINUES IN THE 295-300K LAYER. THIS WEAK LIFT HAS LED TO SOME SATURATION IN THE LOWEST LAYERS OF THE ATMOSPHERE...WITH WIDESPREAD STRATUS BUILDING DOWN AS THE EVENING PROGRESSES WITH DRIZZLE AND SOME AREAS OF FOG. THIS DRIZZLE AND FOG WILL BE SHORT LIVED...ESPECIALLY ACROSS CENTRAL KS...AS A STRONG COLD FRONT PUSHES INTO CENTRAL KS BY AROUND 06Z/SUN AND KEEPS PUSHING SOUTH ACROSS THE REST OF THE REGION LATE TONIGHT OR EARLY ON SUN. THIS FRONT WILL SHIFT THE WINDS RAPIDLY AROUND TO THE NORTH AND BECOME GUSTY AT 20 TO 30 MPH. IT WILL ALSO HELP SCOUR OUT MOST OF THE LOW LEVEL MOISTURE IS IT PUSHES SOUTH...ENDING THE DRIZZLE AND FOG AS IT MOVES SOUTH. AS THIS FRONT APPROACHES...WITH A SHORTWAVE PUSHING ACROSS NEB. LIFT ASSOCIATED WITH THIS FRONT AND SHORTWAVE COULD LEAD TO SOME LIGHT RAIN ACROSS CEN KS. COULD SEE THIS LIGHT RAIN CHANCE POSSIBLY TURN OVER OR MIX WITH SOME LIGHT SNOW...AS COLDER AIR ALOFT MOVES ACROSS NEB BY EARLY ON SUN. BUT LACK OF DEEP MOISTURE WILL MAINLY LEAD TO VERY LIGHT PRECIPITATION...WITH MAINLY FLURRIES AS IT TURNS OVER TO SNOW. KETCHAM PREV DISCUSSION... /ISSUED 556 PM CST SAT DEC 8 2012/ AVIATION...00Z TAFS KRSL/KSLN/KHUT/KICT/KCNU LOW LEVEL ISENTROPIC LIFT FROM THE SOUTH-SOUTHWEST WILL LEAD TO DETERIORATING FLIGHT CONDITIONS THIS EVENING...AS WIDESPREAD MVFR CIGS/VSBYS AND AREAS OF IFR CIGS PUSH INTO THE AREA THROUGH THE EVENING HOURS. BOTH THE NAM/WRF AND GFS NOT HANDLING THIS LOWER CEILING TREND VERY WELL...WITH THE LATEST RUC40 CLOSER TO REALITY. EVEN WENT MORE PESSIMISTIC THAN THE RUC ON CEILINGS AND FOG. A COLD FRONTAL BOUNDARY LOOKS TO ARRIVE AFTER 06Z/SUN ACROSS CENTRAL KANSAS...AND FURTHER SOUTH ACROSS SOUTH CENTRAL KS AFTER 09-10Z/SUN. THIS WILL LEAD TO CEILINGS BEGINNING TO LIFT WITH MVFR/VFR CEILINGS FOR THE MORNING HOURS ON SUN. WINDS BEHIND THE FRONT WILL INCREASE TO 20-30 KTS WITH SOME LIGHT SNOW DEVELOPING ACROSS PORTIONS OF CENTRAL KANSAS ON SUNDAY. NOT EXPECTING THE LIGHT SNOW TO RESTRICT VSBYS MUCH...AS THIS WILL BE MAINLY A LIGHT SNOW EVENT/FLURRY EVENT. KETCHAM PREV DISCUSSION... /ISSUED 311 PM CST SAT DEC 8 2012/ DISCUSSION... MAIN FORECAST CONCERNS ARE PRECIP CHANCES AND TYPE TONIGHT THROUGH SUN ALONG WITH HOW COLD TO GO FOR SUN-MON. SYNOPSIS: STRONG SHORTWAVE IS DIVING OVER THE NORTHERN ROCKIES AND APPROACHING THE NORTHERN HIGH PLAINS. AT THE SURFACE...TROUGHING EXTENDS FROM SW SD INTO EASTERN CO. THIS HAS LEFT WARM MOIST FLOW OVER THE SOUTHERN AND CENTRAL PLAINS WHICH HAS ALLOWED LOW CLOUDS TO MOVE BACK IN ACROSS MUCH OF THE FORECAST AREA. TONIGHT-SUN NIGHT: WITH THE LOW LEVEL WARM MOIST FLOW REMAINING IN PLACE...THINKING THAT THE LOW CLOUDS WILL MAINTAIN AND WILL LIKELY LOWER A BIT THIS EVENING. IN ADDITION ALSO FEEL THAT AFTER DARK SOME LIGHT FOG AND DRIZZLE WILL ACCOMPANY THE LOW CIGS. MID LEVEL LIFT WILL COMMENCE OVER CENTRAL AND NORTHEAST KS THIS EVENING WHICH SHOULD RESULT IN SOME LIGHT SHOWERS WITH SOME OF THESE SHOWERS TRANSITIONING TO SOME LIGHT SNOW AFTER AFTER 3 AM AS MUCH COLDER AIR STARTS TO SPILL-IN FROM THE NORTH. NOT EXPECTING ANYTHING IN THE WAY OF ACCUMULATION OVERNIGHT. JUST LIKE THE LAST FEW MODEL RUNS...THE MAIN PIECE OF ENERGY IS EXPECTED TO BREAK OFF INTO TWO PIECES. ONE WILL MOVE TOWARDS THE GREAT LAKES WHILE THE OTHER DIVES OVER THE DESERT SW AND EVENTUALLY THE SOUTHERN PLAINS. STILL THINKING THAT THE PRECIP ON SUN WILL PRIMARILY BE IN THE FORM OR FLURRIES AND SPRINKLES. THE EXCEPTION WOULD BE THE EAST AND NORTHEAST FRINGES OF THE FORECAST AREA WHERE THE DEEPER LIFT AND MOISTURE WILL BE SITUATED. EVEN THE LOCATIONS THAT DO SEEM SOME SNOW SHOWERS CAN EXPECT TO ONLY PICKUP VERY LIGHT AMOUNTS. THE MAIN STORY WITH THIS SYSTEM WILL CONTINUE TO BE THE COLDEST TEMPS OF THE SEASON SO FAR WITH SINGLE DIGITS A GOOD BET FOR MUCH OF CENTRAL KS MON MORNING. MON-SAT: THE LONGWAVE TROUGH IS EXPECTED TO POSITION ITSELF OVER THE CENTRAL CONUS TO START THE WORK WEEK AS ADDITIONAL UPPER IMPULSES DIVE DOWN THE BACKSIDE OF THE TROUGH AND ACROSS THE SOUTHERN PLAINS FOR MON NIGHT INTO TUE. THIS PATTERN WILL RESULT IN A CONTINUATION OF BELOW NORMAL TEMPS WITH THE MOISTURE AND ASSOCIATED PRECIP CHANCES PUSHED WELL EAST OF THE FORECAST AREA. BY MID WEEK THE UPPER PATTERN WILL QUICKLY TRANSITION FROM NW FLOW ALOFT TO SW FLOW BY WED AFTERNOON AS OUR NEXT SHORTWAVE DIGS OVER THE WEST COAST. THIS WILL GET THE PLAINS BACK INTO A WARMING PATTERN THAT WILL CONTINUE FOR THU INTO FRI. THE SHORTWAVE WILL START TO DIRECTLY IMPACT THE AREA BY FRI INTO SAT. THE ECMWF IS MUCH MORE COMPACT THE MORE PROGRESSIVE WITH THIS WAVE COMPARED TO THE GFS. REGARDLESS OF WHICH ONE VERIFIES IT APPEARS THE BEST SNOW CHANCES WILL BE NORTH OF THE FORECAST AREA WITH SOME SHOWERS AND EVEN A FEW STORMS POSSIBLE FOR FRI...TRANSITIONING TO SOME LIGHT SNOW OR FLURRIES FOR FRI NIGHT. LAWSON && .PRELIMINARY POINT TEMPS/POPS... WICHITA-KICT 35 38 13 35 / 10 10 10 0 HUTCHINSON 34 35 12 36 / 10 10 10 0 NEWTON 34 37 12 35 / 10 20 10 0 ELDORADO 36 39 14 34 / 10 20 10 0 WINFIELD-KWLD 37 39 15 36 / 10 20 10 0 RUSSELL 28 32 6 39 / 20 10 10 0 GREAT BEND 31 33 7 38 / 10 10 10 0 SALINA 31 32 10 37 / 20 10 10 0 MCPHERSON 34 35 11 36 / 20 10 10 0 COFFEYVILLE 44 45 19 36 / 10 30 10 10 CHANUTE 42 43 18 34 / 10 30 10 10 IOLA 41 43 17 33 / 10 30 10 10 PARSONS-KPPF 43 44 18 35 / 10 30 10 10 && .ICT WATCHES/WARNINGS/ADVISORIES... NONE. && $$
AREA FORECAST DISCUSSION
NWS GOODLAND KS
1018 PM MST SAT DEC 8 2012 .UPDATE... ISSUED AT 757 PM MST SAT DEC 8 2012 PER SATELLITE AND LATEST MODEL DATA INCREASED CLOUD COVER THROUGH TOMORROW MORNING. LOOKING AT CURRENT SURFACE OBSERVATION DATA AND CONSIDERING THE HIGHER WINDS/MORE CLOUD COVER...CHOSE TO RAISE MINS A LITTLE WHICH DOES FIT WITH SOME OF THE NEWER GUIDANCE. CURRENT PRECIPITATION FORECAST LOOKS FINE. WINDS WILL BEGIN GUSTING TO JUST UNDER WIND ADVISORY CRITERIA. IT LOOKS CLOSE FOR WIND ADVISORY AND WILL LET THE OVERNIGHT SHIFT ADDRESS THAT. GRIDS ARE ALREADY REFLECTING IT. UPDATE ISSUED AT 605 PM MST SAT DEC 8 2012 JUST COMPLETED AN UPDATE. FIRST FRONT IN A SERIES OF FRONTS ALREADY BLASTING THROUGH WHICH IS FASTER THAN ANY MODEL DEPICTION OR WHAT THE GRIDS HAD WHICH IS NOT UNCOMMON IN THIS SCENARIO. NOT ONLY IS THE FRONT THROUGH...BUT WIND SPEEDS ALREADY TO NEAR 40 MPH IN SOME LOCATIONS. RUC WAS THE FASTEST MODEL BUT WAS STILL A LITTLE SLOW AND UNDERDONE ON THE SPEEDS. SO USED IT AND MODIFIED WITH REALITY. HOPEFULLY NEWER MODEL DATA WILL CATCH UP WITH THIS. ALSO INCREASED SPEEDS FOR LATER TONIGHT AND TOMORROW AS WELL WITH WHAT LOOKS TO BE DECENT MIXING. CONSIDERING THE COLD AIR ADVECTION ALREADY OCCURRING...THERE MAY NOT BE ANY LOW LEVEL INVERSION TO OVERCOME AND WIND SPEEDS MAY BE EVEN HIGHER THAN WHAT I HAVE DEPICTED. WILL CONTINUE TO WATCH AND TWEAK AS NEWER DATA COMES IN. && .SHORT TERM...(THIS AFTERNOON THROUGH SUNDAY) ISSUED AT 1059 AM MST SAT DEC 8 2012 EXCEPT FOR THE COLD AIR MOVING IN BEHIND THE FRONT THIS EVENING AND OVERNIGHT...THIS EVENT IS BEGINNING TO LOOK MORE LIKE A NON- EVENT. HAVE TONED DOWN THE MENTION OF ANY ACCUMULATING SNOW AND HAVE PUT IN A MENTION OF SPRINKLES OR FLURRIES IN THE FAR NORTHWEST CORNER OF THE FORECAST AREA BEFORE 00Z WITH A MORE EXTENSIVE AREA OF FLURRIES ALONG AND BEHIND THE FRONT AS IT MOVES THROUGH THE FORECAST AREA TONIGHT. THE NAM CONTINUES TO BE DRY WITH THE ECMWF AND GFS ONLY PRODUCING AROUND ONE HUNDREDTH OF QPF ALONG THE NORTHERN AND WESTERN FRINGES OF THE FORECAST AREA. FLURRIES WILL DIMINISH EARLY SUNDAY WITH SKIES BEGINNING TO CLEAR BY LATE SUNDAY AFTERNOON AS SURFACE HIGH PRESSURE BEGINS TO MOVE INTO THE REGION. BECAUSE OF THE DECREASING CLOUDS COVER AND SLACKENING WINDS SUNDAY NIGHT...EXPECT THE COLDEST TEMPERATURES OF THE SEASON WITH LOWS DROPPING DOWN TO AROUND ZERO IN SOME LOCATIONS. WIND CHILL BELOW ZERO WILL BE COMMON. .LONG TERM...(SUNDAY NIGHT THROUGH SATURDAY) ISSUED AT 112 PM MST SAT DEC 8 2012 SUNDAY NIGHT THROUGH TUESDAY NIGHT THE BASE OF THE LONG WAVE TROUGH WILL REMAIN OVER THE AREA. SUNDAY NIGHT THE TROUGH AXIS...FROM THE SHORT WAVE TROUGH RESPONSIBLE FOR THE WINTER STORM OVER THE NORTHERN PLAINS...WILL MOVE THROUGH THE AREA. UNFORTUNATELY DRIER AIR WILL BE OVER THE AREA BY THE TIME THE TROUGH AXIS MOVES THROUGH AND THE LEFT ENTRANCE OF THE 500-300MB JET WILL BE OVER THE AREA AHEAD OF THE TROUGH AXIS...LEADING TO DRY CONDITIONS FOR THE AREA. WINDS WILL DECREASE DURING THE EVENING AS A SURFACE HIGH BUILDS INTO THE AREA. WITH LITTLE TO NO WIND AND CLEAR SKIES...TEMPERATURES WILL FALL TO THE SINGLE DIGITS. ANY WIND THAT DOES DEVELOP WILL PRODUCE WIND CHILL VALUES NEAR 15 BELOW ZERO. MONDAY SEVERAL WEAKER SHORT WAVE TROUGHS MOVE THROUGH...BUT THERE WILL BE LITTLE TO NO MOISTURE TO WORK WITH. DURING THE LATE AFTERNOON/EVENING AREA SOUNDINGS SATURATE AS MOISTURE MOVES INTO THE AREA BEHIND A SURFACE AND UPPER LEVEL TROUGH. HOWEVER THE INCREASED MOISTURE WILL BE IN THE SUBSIDENCE AREA BEHIND THE SHORT WAVE TROUGH. FOR THE TUESDAY THROUGH SATURDAY PERIOD...DRY CONDITIONS WILL CONTINUE TO PREVAIL. THE LONG WAVE TROUGH MOVES EAST TUESDAY ALLOWING A LONG WAVE RIDGE TO MOVE OVER THE CENTRAL PLAINS THROUGH THE MAJORITY OF NEXT WEEK. MEANWHILE THE NEXT SHORT WAVE TROUGH MOVES ONSHORE WEDNESDAY...APPROACHING THE AREA FRIDAY. MODELS AGREE WITH THE TRACK OF THE TROUGH...MOVING IT OVER THE TEXAS AND OKLAHOMA PANHANDLES. THE POSITION OF THE TROUGH IS STILL TOO FAR SOUTH FOR THE AREA TO RECEIVE ANY PRECIPITATION. HOWEVER THE MODELS HAVE TRENDED FURTHER NORTH WITH THE TROUGH SINCE YESTERDAY. FRIDAY NIGHT THE GEFS MEMBERS INDICATED A SLIGHT CHANCE FOR SOME PRECIPITATION OVER THE EASTERN PART OF THE AREA. GFS ISENTROPIC LIFT DOES SHOW SOME LIFT AND MOISTURE CO-LOCATED AROUND 600MB OVER THOSE LOCATIONS. IF THIS FEATURE IS STILL THERE TOMORROW...SLIGHT CHANCES MAY NEED TO BE ADDED FOR THE EAST FRIDAY NIGHT. TEMPERATURES WILL BE NEAR NORMAL...WITH A SMALL WARMING TREND THROUGH THE PERIOD. A COLD FRONT WILL MOVE THROUGH FRIDAY BEHIND THE UPPER LEVEL TROUGH...BUT THE COOLER AIR MASS BEHIND THE FRONT WILL QUICKLY MOVE EAST FOLLOWING THE UPPER LEVEL TROUGH. THIS WILL ALLOW TEMPERATURES FOR SATURDAY TO REMAIN LARGELY UNAFFECTED BY THE FRONTAL PASSAGE. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SUNDAY NIGHT) ISSUED AT 1016 PM MST SAT DEC 8 2012 VFR CONDITIONS ARE EXPECTED THROUGH THE PERIOD. SOME LOW CLOUDS COULD OCCUR BUT ARE EXPECTED TO SCATTERED AND NEAR TO SLIGHTLY ABOVE MVFR. STRONG AND GUSTY NORTH TO NORTHWEST WILL CONTINUE NEAR SUNSET. && .GLD WATCHES/WARNINGS/ADVISORIES... KS...NONE. CO...NONE. NE...NONE. && $$ UPDATE...BULLER SHORT TERM...LOCKHART LONG TERM...JTL AVIATION...BULLER
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
456 AM EST SUN DEC 9 2012 .SYNOPSIS... LOW PRESSURE COMING NORTHEAST FROM MISSOURI WILL BRING THE UPPER OHIO VALLEY...MILD TEMPERATURES AND BOUTS OF RAIN INTO MONDAY... FOLLOWED BY A COOL DOWN TO SEASONABLE TEMPERATURES TUESDAY. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... BASED OF BLEND OF RECENT SREF MODEL OUTPUT...WITH DETAILS FROM RECENT RAP WRF-NMM AND NAM MODEL RUNS...SHOW A LOW PRESSURE SYSTEM WILL BE MOVING FROM MISSOURI THIS MORNING TO OHIO THIS EVENING. WARM FRONT CONVERGENCE ENHANCED BY JETSTREAM DYNAMICS ALOFT WILL SPAWN A SURGE OF RAIN TO SPREAD NORTHWARD ACROSS THE UPPER OHIO TODAY. LOCATIONS SOUTH OF THE I-70 CORRIDOR CAN EXPECT BOUTS OF RAIN STARTING THIS MORNING...WHILE LOCATIONS FARTHER NORTH MAY NOT GET MUCH RAIN UNTIL AFTERNOON. HAVE ADDED MENTION OF DENSE FOG ACROSS THE HIGHER ELEVATIONS OF TUCKER WV COUNTY AND GARRETT CO MD COUNTY...BASED ON RECENT SURFACE DATA. FOG SHOULD CONTINUE INTO MID MORNING WHEN FIRST BOUT OF RAIN LESSENS. TEMPERATURES WILL CONTINUE TO BE MILD WITH HIGHS THIS AFTERNOON ABOUT 15 DEGREES WARMER THAN NORMAL...PER BLEND OF GFS AND NAM MOS AND RAP AND GFS LAMP HOURLY VALUES. && .SHORT TERM /6 PM THIS EVENING THROUGH WEDNESDAY/... RECENT SREF MODEL OUTPUT SHOWS A NORTHEAST SURGE OF MODERATE RAIN ACROSS THE UPPER OHIO TONIGHT AND MONDAY...UNTIL THE LOW PRESSURE CENTER PASSES NORTHEAST TO NEW YORK STATE MONDAY AFTERNOON. CONCUR WITH HPC THAT RAIN AMOUNTS FOR THIS EVENT CAN BE ON THE ORDER OF 1.0 TO 1.3 INCHES. TEMPERATURES WILL REMAIN MILD WITH VALUES MAINLY IN THE UPPER 40S TO MID 50S INTO MIDDAY MONDAY. ONCE THE LOW PRESSURE CENTER EXITS NORTHEAST...A COLD FRONTAL PASSAGE WILL ENSUE MONDAY AFTERNOON. THE COOL DOWN CAN BEGIN MONDAY AFTERNOON WITH VALUES LATE MONDAY NIGHT INTO WEDNESDAY NEAR OR SLIGHTLY COLDER THAN NORMAL. CONSEQUENTLY REMAINING POSTFRONTAL SHOWERS MONDAY NIGHT CAN TURN TO SNOW SHOWERS LATE. THE POSTFRONTAL COLD POOL CAN REMAIN ACROSS THE UPPER OHIO VALLEY INTO WEDNESDAY...KEEPING SKIES MAINLY CLOUDY. HOWEVER CONDITIONS TUESDAY INTO WEDNESDAY SHOULD BE DRY AS INCOMING HIGH PRESSURE SUBSIDENCE AND LOW LEVEL WESTERLY WINDS WILL MITIGATE CHANCES OF LAKE EFFECT SNOW SHOWER DEVELOPMENT. && .LONG TERM /WEDNESDAY NIGHT THROUGH SATURDAY/... GFS ECMWF AND CANADIAN MODEL OUTPUT CONCUR THAT NEARBY HIGH PRESSURE WILL PROMOTE DRY CONDITIONS WEDNESDAY NIGHT INTO FRIDAY. ECMWF AND GFS AGREE THAT A CLOSED MID-LEVEL LOW WILL DEVELOP ACROSS THE CENTRAL PLAINS ON FRIDAY NIGHT AND SHIFT INTO THE GREAT LAKES REGION BY SATURDAY. AHEAD OF THIS FEATURE...CHANCE POPS RETURN TO THE AREA. MODEL PREDICTABILITY A WEEK OUT MAKES IT DIFFICULT TO PIN DOWN SPECIFICS IN FRONTAL PLACEMENT...HOWEVER THIS PATTERN FAVORS THE POTENTIAL FOR OVERRUNNING ALONG WITH WARM FRONTAL RAIN SHOWERS WELL AHEAD OF THE LOW. TEMPERATURES WILL REBOUND TO WARMER THAN NORMAL THIS PERIOD WITH VALUES FRIDAY AND SATURDAY ANYWHERE FROM 5 TO 10 DEGREES ABOVE NORMAL. && .AVIATION /10Z SUNDAY THROUGH THURSDAY/... CONDITIONS SHOULD REMAIN MVFR THROUGH MUCH OF THE DAY. ALTHOUGH CURRENT TAFS DEPICT RAIN BEGINNING TO AFFECT TERMINALS BY NOON...INCOMING MODEL RUNS SUGGEST THAT IT MAY TAKE LONGER FOR SHOWERS ASSOCIATED WITH A WARM FRONT TO MOVE INTO THE AREA. CEILINGS WILL LOWER TO IFR AFTER A FEW HOURS OF RAIN. WINDS WILL SHIFT FROM NORTHEAST TO THE SOUTHEAST DURING THE DAY...WHICH COULD ALLOW FOR A BRIEF INCREASE OF WINDS AT KLBE DUE TO DOWNSLOPING. WINDS WILL BECOME SOUTHERLY ONCE THE WARM FRONT MOVES THROUGH THIS EVENING. .OUTLOOK.../MONDAY THROUGH THURSDAY/... MVFR AND PSBL IFR RESTRICTIONS WL CONTINUE WITH RAIN MONDAY AS A COLD FRONT MOVES THROUGH. MVFR CONDITIONS ARE EXPECTED MONDAY NIGHT INTO TUESDAY. LINGERING RAIN SHOWERS MAY CHANGE TO SCATTERED SNOW SHOWERS BEFORE ENDING EARLY TUESDAY. HIGH PRES AND VFR CONDS ARE EXPECTED LATER TUESDAY THROUGH THURSDAY. && .PBZ WATCHES/WARNINGS/ADVISORIES... MD...NONE. OH...NONE. PA...NONE. WV...NONE. && $$
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
420 AM EST SUN DEC 9 2012 .SYNOPSIS... LOW PRESSURE COMING NORTHEAST FROM MISSOURI WILL BRING THE UPPER OHIO VALLEY...MILD TEMPERATURES AND BOUTS OF RAIN INTO MONDAY... FOLLOWED BY A COOL DOWN TO SEASONABLE TEMPERATURES TUESDAY. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... BASED OF BLEND OF RECENT SREF MODEL OUTPUT...WITH DETAILS FROM RECENT RAP WRF-NMM AND NAM MODEL RUNS...SHOW A LOW PRESSURE SYSTEM WILL BE MOVING FROM MISSOURI THIS MORNING TO OHIO THIS EVENING. WARM FRONT CONVERGENCE ENHANCED BY JETSTREAM DYNAMICS ALOFT WILL SPAWN A SURGE OF RAIN TO SPREAD NORTHWARD ACROSS THE UPPER OHIO TODAY. LOCATIONS SOUTH OF THE I-70 CORRIDOR CAN EXPECT BOUTS OF RAIN STARTING THIS MORNING...WHILE LOCATIONS FARTHER NORTH MAY NOT GET MUCH RAIN UNTIL AFTERNOON. TEMPERATURES WILL CONTINUE TO BE MILD WITH HIGHS THIS AFTERNOON ABOUT 15 DEGREES WARMER THAN NORMAL...PER BLEND OF GFS AND NAM MOS AND RAP AND GFS LAMP HOURLY VALUES. && .SHORT TERM /6 PM THIS EVENING THROUGH WEDNESDAY/... RECENT SREF MODEL OUTPUT SHOWS A NORTHEAST SURGE OF MODERATE RAIN ACROSS THE UPPER OHIO TONIGHT AND MONDAY...UNTIL THE LOW PRESSURE CENTER PASSES NORTHEAST TO NEW YORK STATE MONDAY AFTERNOON. CONCUR WITH HPC THAT RAIN AMOUNTS FOR THIS EVENT CAN BE ON THE ORDER OF 1.0 TO 1.3 INCHES. TEMPERATURES WILL REMAIN MILD WITH VALUES MAINLY IN THE UPPER 40S TO MID 50S INTO MIDDAY MONDAY. ONCE THE LOW PRESSURE CENTER EXITS NORTHEAST...A COLD FRONTAL PASSAGE WILL ENSUE MONDAY AFTERNOON. THE COOL DOWN CAN BEGIN MONDAY AFTERNOON WITH VALUES LATE MONDAY NIGHT INTO WEDNESDAY NEAR OR SLIGHTLY COLDER THAN NORMAL. CONSEQUENTLY REMAINING POSTFRONTAL SHOWERS MONDAY NIGHT CAN TURN TO SNOW SHOWERS LATE. THE POSTFRONTAL COLD POOL CAN REMAIN ACROSS THE UPPER OHIO VALLEY INTO WEDNESDAY...KEEPING SKIES MAINLY CLOUDY. HOWEVER CONDITIONS TUESDAY INTO WEDNESDAY SHOULD BE DRY AS INCOMING HIGH PRESSURE SUBSIDENCE AND LOW LEVEL WESTERLY WINDS WILL MITIGATE CHANCES OF LAKE EFFECT SNOW SHOWER DEVELOPMENT. && .LONG TERM /WEDNESDAY NIGHT THROUGH SATURDAY/... GFS ECMWF AND CANADIAN MODEL OUTPUT CONCUR THAT NEARBY HIGH PRESSURE WILL PROMOTE DRY CONDITIONS WEDNESDAY NIGHT INTO FRIDAY. ECMWF AND GFS AGREE THAT A CLOSED MID-LEVEL LOW WILL DEVELOP ACROSS THE CENTRAL PLAINS ON FRIDAY NIGHT AND SHIFT INTO THE GREAT LAKES REGION BY SATURDAY. AHEAD OF THIS FEATURE...CHANCE POPS RETURN TO THE AREA. MODEL PREDICTABILITY A WEEK OUT MAKES IT DIFFICULT TO PIN DOWN SPECIFICS IN FRONTAL PLACEMENT...HOWEVER THIS PATTERN FAVORS THE POTENTIAL FOR OVERRUNNING ALONG WITH WARM FRONTAL RAIN SHOWERS WELL AHEAD OF THE LOW. TEMPERATURES WILL REBOUND TO WARMER THAN NORMAL THIS PERIOD WITH VALUES FRIDAY AND SATURDAY ANYWHERE FROM 5 TO 10 DEGREES ABOVE NORMAL. && .AVIATION /09Z SUNDAY THROUGH THURSDAY/... CONDITIONS SHOULD REMAIN MVFR THROUGH MUCH OF THE DAY. ALTHOUGH CURRENT TAFS DEPICT RAIN BEGINNING TO AFFECT TERMINALS BY NOON...INCOMING MODEL RUNS SUGGEST THAT IT MAY TAKE LONGER FOR SHOWERS ASSOCIATED WITH A WARM FRONT TO MOVE INTO THE AREA. CEILINGS WILL LOWER TO IFR AFTER A FEW HOURS OF RAIN. WINDS WILL SHIFT FROM NORTHEAST TO THE SOUTHEAST DURING THE DAY...WHICH COULD ALLOW FOR A BRIEF INCREASE OF WINDS AT KLBE DUE TO DOWNSLOPING. WINDS WILL BECOME SOUTHERLY ONCE THE WARM FRONT MOVES THROUGH THIS EVENING. .OUTLOOK.../MONDAY THROUGH THURSDAY/... MVFR AND PSBL IFR RESTRICTIONS WL CONTINUE WITH RAIN MONDAY AS A COLD FRONT MOVES THROUGH. MVFR CONDITIONS ARE EXPECTED MONDAY NIGHT INTO TUESDAY. LINGERING RAIN SHOWERS MAY CHANGE TO SCATTERED SNOW SHOWERS BEFORE ENDING EARLY TUESDAY. HIGH PRES AND VFR CONDS ARE EXPECTED LATER TUESDAY THROUGH THURSDAY. && .PBZ WATCHES/WARNINGS/ADVISORIES... MD...NONE. OH...NONE. PA...NONE. WV...NONE. && $$
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
117 AM EST SUN DEC 9 2012 .SYNOPSIS... A NORTHEASTBOUND LOW PRESSURE SYSTEM FROM ARKANSAS WILL BRING MILD TEMPERATURES AND BOUTS OF RAIN TO THE UPPER OHIO VALLEY INTO MONDAY...THEN A COOL DOWN TO SEASONABLE TEMPERATURES TUESDAY. && .NEAR TERM /THROUGH TODAY/... HAVE FORECASTED A SLIGHTLY SLOWER NORTHWARD SPREAD OF RAIN ACROSS THE UPPER OHIO VALLEY TODAY...BASED ON BLEND OF RECENT SREF MODEL OUTPUT WITH DETAILS FROM RECENT RAP WRF-NMM AND NAM MODEL RUNS. TEMPERATURES WILL CONTINUE MILD WITH NEAR STEADY TEMPERATURES OVERNIGHT AND HIGHS SUNDAY AFTERNOON ABOUT 15 DEGREES WARMER THAN NORMAL. && .SHORT TERM /TONIGHT THROUGH TUESDAY/... EXPECT WIDESPREAD RAIN TO CONTINUE SUNDAY NIGHT INTO MONDAY AS FRONT GRADUALLY CROSSES REGION AS MAIN SURFACE LOW MOVES TO NEW ENGLAND AND UPPER TROUGH SLOWLY SHIFTS EAST. RAIN WILL BEGIN TO SHIFT SOUTHEAST WITH FRONT LATE DAY MONDAY AND AS COLDER AIR WORKS IN SOME CHANGE OVER TO SNOW SHOWERS WILL OCCUR MONDAY NIGHT. TOTAL RAINFALL FOR THE EVENT WILL BE AROUND AN INCH BUT WILL BE SPREAD OVER A 24 TO 36 HOUR PERIOD SO NO FLOOD PROBLEMS EXPECTED. SCATTERED SNOW SHOWERS MONDAY NIGHT INTO TUESDAY WILL NOT AMOUNT TO MUCH AS DEEP MOISTURE WILL HAVE BEEN SHUNTED WELL EAST. FLOW OFF THE LAKES WILL BE WEAK MONDAY NIGHT AND TUESDAY DESPITE 85OMB TEMPS REACHING -9C ACROSS THE LAKES BY 12Z TUESDAY. QUITE MILD SUNDAY NIGHT AHEAD OF THE FRONT THEN A GRADUAL FALL WITH FROPA MONDAY. BACK TO NEAR NORMAL FOR MONDAY NIGHT AND TUESDAY. && .LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/... GFS/ECMWF/CANADIAN ARE IN AGREEMENT THAT A SURFACE HIGH WILL BUILD IN FROM THE SOUTHWEST TUESDAY NIGHT INTO WEDNESDAY AND BECOME CENTERED OVER THE UPPER OHIO VALLEY BY AROUND 00Z THURSDAY. THERE ARE SOME MODEL INCONSISTENCIES IN THE PASSAGE OF AN UPPER TROUGH...HOWEVER SUBSIDENCE AND DRY AIR IN THE LOWER LEVEL WILL KEEP THE FORECAST DRY REGARDLESS OF ITS TIMING. THUS...A DRY FORECAST IS IN PLACE THROUGH FRIDAY. ECMWF/GFS AGREE THAT A CLOSED MID-LEVEL LOW WILL DEVELOP ACROSS THE CENTRAL PLAINS ON FRIDAY NIGHT AND SHIFT INTO THE GREAT LAKES REGION BY SATURDAY. AHEAD OF THIS FEATURE...CHANCE POPS RETURN TO THE AREA. MODEL PREDICTABILITY A WEEK OUT MAKES IT DIFFICULT TO PIN DOWN SPECIFICS IN FRONTAL PLACEMENT...HOWEVER THIS PATTERN FAVORS THE POTENTIAL FOR OVERRUNNING ALONG WITH WARM FRONTAL RAIN SHOWERS WELL AHEAD OF THE LOW. TEMPERATURES WILL BE NEAR SEASONAL NORMALS ON WEDNESDAY WITH THE POST-FRONTAL CANADIAN AIR MASS STILL IN PLACE BEHIND THE FRONT AND SOME INCREASED CLOUDINESS FROM THE PASSING MID-LEVEL TROUGH. THE MID-LEVEL FLOW WILL BECOME MORE SOUTHWESTERLY THURSDAY THROUGH SATURDAY...ALLOWING FOR TEMPS TO BE AROUND 5 TO 10 DEGREES ABOVE NORMAL. && .AVIATION /06Z SUNDAY THROUGH THURSDAY/... SFC ANALYSIS SHOWING A COLD FRONT FROM SW PA INTO NRN WV. THE FRONT WL CONTINUE TO DRIFT SWD TONIGHT. EXPECTING MVFR NR THE FRONT...WITH A BRIEF PD OF VFR BEHIND THE FRONT. MVFR...AND EVEN SOME IFR AT THE NRN TAF SITES...WL THEN RETURN AND PERSIST MUCH OF THE NIGHT. THE FRONT STARTS TO RETURN N AS A WARM FRONT ERLY SUN MRNG. THIS WL SPREAD RAIN INTO THE SRN TAF SITES. MOST OF THE RAIN ELSEWHERE SHOULD MOVE IN DURING THE MID-LATE AFTN SUN WITH LOW END MVFR. EXPECTING GRADUALLY VEERING WINDS THROUGH THE PD. .OUTLOOK.../SUNDAY NIGHT THROUGH THURSDAY/... MVFR AND PSBL IFR RESTRICTIONS WL CONTINUE WITH RAIN SUNDAY NIGHT INTO MONDAY AS A COLD FRONT MOVES THROUGH. MVFR CONDS AND A FEW SNOW SHOWERS ARE PSBL MONDAY NIGHT INTO ERLY TUE. HIGH PRES AND VFR CONDS ARE EXPECTED LATER TUE THROUGH THU. && .PBZ WATCHES/WARNINGS/ADVISORIES... MD...NONE. OH...NONE. PA...NONE. WV...NONE. && $$
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
1240 AM EST SUN DEC 9 2012 .UPDATE... ISSUED AT 739 PM EST SAT DEC 8 2012 WITH MOCLR SKIES OVER THE W HALF OF UPR MI UNDER SFC RDG AXIS/PWAT 0.18 INCH AS OBSVD ON THE 00Z GRB RAOB...SFC TEMPS HAVE ALREADY REACHED FCST MINS EARLY THIS EVNG. SO TENDED TO LOWER THESE NUMBERS A COUPLE OF DEGREES OVER THE W HALF BEFORE INCRSG HI CLDS FM THE SW ARRIVE BY MIDNGT AND AT LEAST STEADY OFF THE TEMP DROP. && .SHORT TERM...(THIS EVENING THROUGH SUNDAY) ISSUED AT 340 PM EST SAT DEC 8 2012 HIGH PRESSURE IS CURRENTLY LOCATED IN MANITOBA AND ONTARIO...WITH A RIDGE STRETCHING SOUTHEAST INTO WESTERN UPPER MI AND WI. LIGHT NORTHWEST FLOW...WITH RUC ANALYZED H850 OF -10 TO -12C...HAS LED TO LAKE EFFECT CLOUDS AND LIGHT SNOW SHOWERS THROUGH THIS AFTERNOON IN THE TRADITIONAL NORTHWEST FLOW LOCATIONS. UPSTREAM...PV ANOMALY IN SRN SD AND NW NEBRASKA WILL SHIFT ENE TONIGHT AND INTO MN BY 12Z SUNDAY...WITH THE SURFACE LOW FOLLOWING SUIT. THIS ANOMALY WILL SHIFT NORTHEAST THROUGH WESTERN UPPER MICHIGAN THROUGH THE DAY ON SUNDAY AND BE WEAKENING DUE TO INFLUENCE OF SECOND ANOMALY ENTERING NORTHERN MN AND THE SOUTHERN WAVE BECOMING MORE DOMINATE AS IT DIVES SOUTHEAST THROUGH THE CENTRAL ROCKIES DURING THE DAY ON SUNDAY. THIS...COMBINED WITH A STRENGTHENING JET OVER THE OHIO VALLEY ON SUNDAY...WILL ALLOW A SECONDARY LOW TO DEVELOP IN THE OHIO VALLEY REGION DURING THE DAY AND PRODUCE A BROAD AREA OF LOW PRESSURE WHICH TRANSITIONS THE LOW OVER OUR AREA TO A TROUGH. STILL DIFFERENCES IN THE MODELS...BOTH RUN-TO-RUN AND BETWEEN MODELS...WITH THE POTENTIAL WEAKENING/SPEED OF THE PV ANOMALY AND THE LOCATION OF THE ASSOCIATED SURFACE TROUGH HEADING INTO SUNDAY AFTERNOON/EVENING. LATEST TRENDS IN THE MODELS ARE FOR A SLOWER MOVEMENT OF THE PV ANOMALY THROUGH UPPER MICHIGAN ON SUNDAY...WHICH KEEPS THE SURFACE TROUGH AXIS OVER NORTHERN/CENTRAL WISCONSIN. TONIGHT...THE HIGH PRESSURE RIDGE EXITING TO THE NORTHEAST WILL PRODUCE QUIET WEATHER BEFORE THE SYSTEM. UPSTREAM DRYING THIS AFTERNOON HAS ATE AWAY AT SOME OF THE LAKE EFFECT CLOUDS OVER THE WEST AND ONCE DAYTIME HEATING IS LOST...EXPECT THE SAME TO OCCUR OVER THE INTERIOR LOCATIONS THIS EVENING. THIS CLEARING WILL MAKE FOR TRICKY LOW TEMPERATURES TONIGHT AND FOLLOWED THE PREVIOUS SHIFT BY TRENDED THEM DOWN A LITTLE MORE AS PWATS 65 PERCENT OF NORMAL AND THERE ARE LIGHT WINDS. WENT WITH LOWS IN UPPER TEENS...BUT BASED OFF HOW QUICKLY TEMPS FELL THIS MORNING IN CLEARING AREAS...THAT MAY NOT BE COLD ENOUGH. OTHERWISE...MID/HIGH LEVEL CLOUDS WILL BE ON THE INCREASE FROM THE SOUTHWEST WITH THE APPROACHING SYSTEM. SUNDAY...PRECIPITATION BUILDS IN FROM SOUTHWEST TO NORTHEAST THROUGH THE DAY. STARTING BETWEEN 12-15Z NEAR KIWD...LATE MORNING OR EARLY AFTERNOON OVER THE CENTRAL...AND MID/LATE AFTERNOON OVER THE EAST. WITH THE LATEST SLOWER TRENDS...HAVE DELAYED THE START A COUPLE OF HOURS FROM THE PREVIOUS SHIFT. PLENTY OF COLD AIR ALOFT...SO EXPECT PRECIPITATION TO BE AS ALL SNOW. AS FOR FORCING...BEST MID LEVEL WAA IS FOCUSED OVER THE SOUTH CENTRAL AND NEAR LAKE MICHIGAN THROUGH THE DAY. THIS LINES UP WITH WEAK FGEN BETWEEN H850-650 OVER THE AREA FOR THE AFTERNOON...BUT SEEMS TO FOCUS OVER THE SOUTHEAST HALF OF THE CWA LATE IN THE AFTERNOON. IN ADDITION...BROAD 280-290K ISENTROPIC ASCENT WILL SPREAD OVER THE CWA DURING THE DAY. FINALLY...H850 TEMPS AROUND -9C SHOULD FAVOR SOME LAKE ENHANCEMENT FOR THE KEWEENAW AND ALSO FOR LOCATIONS NEAR LAKE MICHIGAN FAVORED BY ESE WINDS. WITH THE SLIGHT DELAY WITH THE SLOWER ARRIVAL OF THE PV ANOMALY AND SURFACE TROUGH BEING A LITTLE FARTHER SOUTH...BEST PRECIPITATION STRADDLES THE SHORT/LONG TERM TRANSITION. ALL IN ALL...MODEL QPF FOR SUNDAY INTO SUNDAY NIGHT WITH THE SYNOPTIC FEATURES IS IN THE 0.25-0.4IN FOR MOST AREAS AND WHEN COMBINED WITH A SNOW RATIO AROUND 13-15 TO 1...WOULD PUT 3 TO 6 INCHES OF SYNOPTIC SNOW OVER THE AREA THROUGH SUNDAY EVENING. OUTSIDE OF ANY LAKE ENHANCEMENT...THE HIGHEST AMOUNTS SHOULD LINE UP ALONG THE WISCONSIN BORDER WITH THE SLIGHT SOUTH SHIFT OF THE SURFACE TROUGH. THE LONG TERM DISCUSSION WILL COVER THE BULK OF THE HEADLINES...BUT DID DROP THE WATCH OVER THE WESTERN COUNTIES AND HAVE STARTED A LONGER PERIOD ADVISORY FROM WEST TO EAST THROUGH THE DAY ON SUNDAY. .LONG TERM...(SUNDAY NIGHT THROUGH SATURDAY) ISSUED AT 340 PM EST SAT DEC 8 2012 MAIN CONCERN IS WITH SNOWFALL FORECAST FOR THE FIRST 24 HOURS OF THE LONG TERM. SUN NIGHT/MON...IN GENERAL...MODELS ARE IN GOOD AGREEMENT...BUT THERE ARE SUBTLE VARIATIONS AT SMALLER SCALES THAT BECOME MAGNIFIED IN THE SNOWFALL FORECAST. THE DIFFICULTY AND UNCERTAINTY IS DUE TO THE FACT THAT THE SYSTEM OVER THE REGION SUN NIGHT WILL BE MERGING WITH A SRN STREAM SYSTEM OVER THE OHIO VALLEY...PLUS THE FACT THAT MODELS HAVE A HARD TIME CONSISTENTLY HANDLING THE PV ANOMALIES THAT WILL DRIVE A GOOD PORTS OF THE SNOWFALL WITH THIS SYSTEM. LATEST RUNS OF THE GFS/NAM/REGIONAL GEM/REGIONAL WRF ARE NOW IN BETTER AGREEMENT IN BRINGING THE WEAKENING PRIMARY PV ANOMALY FROM NW WI AT 00Z MON TO CENTRAL UPPER MI AROUND 06Z MON...THEN SHEARING IT OUT AND PUSHING IT NORTHEAST BY 12Z MON. MEANWHILE...THE SECONDARY PV ANOMALY WILL ROTATE INTO CENTRAL/SRN WI...FARTHER S THAN PREVIOUS RUNS OF THE MODELS. THE TIMING/LOCATION OF THE PV ANOMALIES IS CONSISTENT WITH THE OVERALL TREND OVER THE LAST FEW RUNS OF THE MODELS IN SLOWING THE SYSTEM DOWN AND MOVING IT FARTHER S. THE RESULTING SFC TROUGH LOOKS TO STAY TO THE S OF THE CWA OVER CENTRAL/NRN WI. LOW LEVEL FLOW WILL GENERALLY BE ELY AT 00Z MON WITH 850MB TEMPS AROUND -9C. BY 06Z MON...LOW LEVEL WINDS BACK TO MORE ENE...THEN TO NNE BY 12Z MON AS 850MB TEMPS FALL TO -11C. SYNOPTIC SNOWFALL AMOUNTS WILL BE HIGHEST OVER THE SRN HALF OF UPPER MI SUN NIGHT...BUT THAT SHOULD BE OFFSET SOME BY UPSLOPE FLOW IN SOME NRN LOCATIONS...PARTICULARLY NCENTRAL UPPER MI AND THE KEWEENAW...THEN OVER THE WRN U.P. LATER SUN NIGHT. 850MB TEMPS FALL ANOTHER COUPLE OF DEGREES THROUGH THE DAY MON WHILE FLOW BECOMES INCREASING ANTICYCLONIC AS THE SFC TROUGH MOVES QUICKLY E AND A RIDGE MOVES OVER WRN LAKE SUPERIOR BY 00Z TUE. THUS...EXPECT LES FROM NNW WINDS MON MORNING...DIMINISHING THROUGH MON EVENING. WITH THIS TYPE OF SYSTEM THERE IS INHERENT UNCERTAINTY THAT WILL PROBABLY NOT BE RESOLVED UNTIL THE SYSTEM IS ON THE DOORSTEP OF THE CWA...SO CONFIDENCE IN SNOWFALL AMOUNTS IS STILL SOMEWHAT LIMITED. STORM TOTAL SNOWFALL AMOUNTS OF 3 TO 6 INCHES IS EXPECTED...WITH SOME LOCALLY HIGHER AMOUNTS POSSIBLE IN THE HIGHER TERRAIN OF WRN GOGEBIC/ONTONAGON COUNTIES AND NW MARQUETTE/NE BARAGA COUNTIES. DECIDED IN COORDINATION WITH SHORT TERM SHIFT TO ISSUE WINTER WX ADVISORIES OVER THE ENTIRE CWA. COULD SEE SOME LOCATIONS GO SLIGHTLY ABOVE ADVISORY CRITERIA...BUT NOT CONFIDENT ENOUGH IN THAT TO JUSTIFY WARNING. ALSO...THE TIME THAT THE HEAVIEST SNOW WILL FALL /SUN EVENING AND EARLY SUN NIGHT/ IS NOT A HIGH IMPACT TIME TRAVEL WISE...PLUS THE FACT THAT THE STORM TOTAL WILL OCCUR OVER 24 HOURS OR MORE. ALSO DECIDED ON THE ADVISORY WITH THE IDEA THAT IT WOULD BE EASIER TO UPGRADE TO A WARNING IF NEEDED THAN HAVE TO CANCEL WARNINGS AND ISSUE AN ADVISORY IF THE BORDERLINE WARNING AMOUNTS DO NOT OCCUR...WHICH WOULD LEAD TO A MISSED EVENT FOR VERIFICATION...SORT OF THE PATH OF LEAST REGRET. A VERY WEAK SHORTWAVE TROUGH MOVES ACROSS THE AREA TUE INTO TUE NIGHT...BRINGING SE FLOW OFF LAKE MICHIGAN FROM 12Z TUE INTO WED. THIS SHOULD LEAD TO LES OFF LAKE MI INTO ERN UPPER MI...ESPECIALLY SERN SCHOOLCRAFT COUNTY. INVERSION HEIGHTS SHOULD BE AROUND 10KFT ACCORDING TO THE NAM/GFS WITH UNIDIRECTIONAL WINDS. THE RESULTING LES BAND SHOULD BE A LARGER MORE DOMINANT ONE...BUT SHOULD ALSO NOT STAY IN ONE PLACE TOO LONG AS WINDS STEADILY VEER. EVEN SO...MAY END UP BEING CLOSE TO ADVISORY AMOUNTS. WINDS WILL BECOME WLY ENOUGH BEHIND THE TROUGH BY 06Z WED TO BRING LES TO NW UPPER MI...BUT WINDS QUICKLY BECOME ANTICYCLONIC BY 12Z WED AS A SFC RIDGE MOVES TO WRN LAKE SUPERIOR...SO LIGHTER SNOW AMOUNTS ARE EXPECTED THERE. A SLIGHTLY STRONGER SYSTEM WILL MOVE N OF THE AREA THU AND DRAW WARMER TEMPS IN THE CWA...BUT NO SIGNIFICANT PRECIP IS EXPECTED. HIGHS IN THE MID TO UPPER 30S SEEMS REASONABLE. PRETTY QUIET AFTER THAT UNTIL MODELS INDICATE A MUCH STRONGER LOW PRESSURE SYSTEM MOVING NEARBY ON SAT. MODELS ARE IN GOOD AGREEMENT FOR HOW FAR OUT THE SYSTEM IS...SO WILL USE CONSENSUS OF MODELS FOR THE FORECAST PAST TUE. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SUNDAY NIGHT) ISSUED AT 1239 AM EST SUN DEC 9 2012 EXPECT PREDOMINANT VFR CONDITIONS THRU AT LEAST THIS MRNG AT ALL THE TAF SITES WITH RDG OF HI PRES/AXIS OF LLVL DRY AIR DOMINATING. THEN LATER TODAY...APRCH OF LO PRES WL BRING SN AND LOWER CIGS/VSBYS SW-NE TO UPR MI. TENDED TO SLOW DOWN THE ONSET OF SN/LOWER CONDITIONS BASED ON NUMERICAL MODEL TRENDS SHOWING A FARTHER S TRACK FOR THE LO PRES/MORE RESILIENT DRY AIR OVER THE UPR LKS. ALTHOUGH SAW IS FARTHER TO THE NE...UPSLOPE ESE WIND MIGHT RESULT IN AN EARLIER ARRIVAL OF THE PCPN/MVFR CIGS. BY EARLY EVNG...CONDITIONS SHOULD DETERIORATE TO IFR AT ALL 3 LOCATIONS. && .MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE) ISSUED AT 340 PM EST SAT DEC 8 2012 AN AREA OF LOW PRESSURE MOVING OUT OF SOUTHWEST SOUTH DAKOTA WILL ENTER MN TOMORROW MORNING AND THEN MERGE WITH A LOW DEVELOPING IN THE GREAT LAKES TO LEAVE A TROUGH OVER NORTHERN WISCONSIN. THIS TROUGH WILL INCREASE WINDS OUT OF THE EAST AND THEN NORTHEAST DIRECTION SUNDAY INTO SUNDAY NIGHT. AT THIS TIME...THINKING WINDS WILL BE IN THE 20-30KT RANGE...ALTHOUGH THERE COULD BE A FEW GALE FORCE GUSTS TO 35KTS OVER THE WEST AS THE TROUGH SHARPENS LATE SUNDAY NIGHT. BEHIND THIS FEATURE...A SERIES OF WEAK RIDGES AND TROUGHS WILL AFFECT LAKE SUPERIOR DURING THE REST OF THE WORK WEEK AND KEEP WINDS BELOW 25KTS. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... WINTER WEATHER ADVISORY FROM 3 PM THIS AFTERNOON TO 7 AM EST MONDAY FOR MIZ006-007-013-014-085. WINTER WEATHER ADVISORY FROM 10 AM EST /9 AM CST/ THIS MORNING TO 7 AM EST /6 AM CST/ MONDAY FOR MIZ001-003-004-010-084. WINTER WEATHER ADVISORY FROM 1 PM THIS AFTERNOON TO 1 PM EST MONDAY FOR MIZ005. WINTER WEATHER ADVISORY FROM 7 AM EST /6 AM CST/ THIS MORNING TO 5 PM EST /4 PM CST/ MONDAY FOR MIZ002-009. WINTER WEATHER ADVISORY FROM 9 AM SUNDAY TO 3 AM CST MONDAY FOR MIZ011-012. LAKE SUPERIOR... NONE. LAKE MICHIGAN... NONE. && $$ UPDATE...KC SHORT TERM...SRF LONG TERM...TITUS AVIATION...KC MARINE...SRF
AREA FORECAST DISCUSSION
NWS TWIN CITIES/CHANHASSEN MN
1135 PM CST SAT DEC 8 2012 .UPDATE... 06Z AVIATION DISCUSSION ADDED BELOW. && .PREV DISCUSSION... /ISSUED 447 PM CST SAT DEC 8 2012/ ..DANGEROUS WINTER STORM TO IMPACT THE UPPER MISSISSIPPI VALLEY TONIGHT THROUGH SUNDAY NIGHT... SHORT TERM...TONIGHT THROUGH TUESDAY NIGHT. LOW PRESSURE LOCATED NEAR VALENTINE NEBRASKA LATE THIS AFTERNOON WILL TRACK ALMOST DUE EAST TONIGHT AND SUNDAY...TRACKING ROUGHLY ALONG THE I-90 CORRIDOR. THIS IS A SIGNIFICANT SHIFT SOUTH FROM WHAT MODELS WERE SHOWING YESTERDAY...WITH THE NAM REMAINING THE LONE NORTHERN OUTLIER TRACKING IT ACROSS THE TWIN CITIES METRO. IN ADDITION...QPF HAS INCREASED MARKEDLY FROM 00Z RUNS AND NOW AVERAGES BETWEEN A HALF AND AT LEAST THREE QUARTERS OF AN INCH FROM WILLMAR TO NEAR LADYSMITH...OR JUST NORTH OF THE METRO. ELSEWHERE...QPF AVERAGES 0.3 TO 0.5 INCHES. THE 18Z GFS IS COMING IN SURPRISINGLY HIGH AT NEARLY ONE INCH AND AGAIN JUST A BIT FURTHER SOUTH FROM PREVIOUS RUNS...NOW THROUGH THE METRO. EVEN THE EC WHICH WAS THE DRY OUTLIER YESTERDAY IS SHOWING AT LEAST 0.6 INCHES OVER MUCH OF THE CENTRAL AREAS. MODEL INCONSISTENCY FROM RUN TO RUN SHOULD NOW BE ABOUT COMPLETE...LEAVING A VERY HIGH PROBABILITY FOR A MAJOR WINTER STORM ACROSS MUCH OF THE AREA TONIGHT INTO SUNDAY EVENING. THE ARC OF SNOW EXPECTED TO PROPAGATE INTO WESTERN MINNESOTA DURING THE NEXT FEW HOURS IS EXPANDING IN SIZE AND PRODUCING MODERATE TO HEAVY SNOWFALL RATES WITHIN EMBEDDED BANDS. WITH TIME...THIS AREA OF SNOW WILL EXPAND WITH WIDESPREAD MODERATE TO HEAVY SNOW EXPECTED TO SPREAD EAST ACROSS THE AREA LATER THIS EVENING AND OVERNIGHT. FRONTOGENESIS WITHIN THE DENDRITIC GROWTH ZONE IS RATHER IMPRESSIVE SO EMBEDDED BANDS OF VERY HEAVY SNOW WITH GREATER THAN ONE INCH HOURLY RATES ARE POSSIBLE THROUGH SUNDAY MORNING. BECAUSE THE TRACK OF THE LOW WILL BE CONFINED TO ABOUT I-90...THE THREAT FOR DRY SLOTTING INTO THE SOUTHERN AREAS IS A BIT LOWER ALTHOUGH STILL POSSIBLE FOR THE SOUTHERN TWO TIERS OF MN COUNTIES COME SUNDAY MORNING. STORM TRACK HAS SLOWED A BIT AS WELL...THUS DEFORMATION SNOW WILL HELP PILE ON THE INCHES A BIT LONGER THAN ANTICIPATED YESTERDAY. OCCASIONAL SNOW OR SNOW SHOWERS ARE EXPECTED THROUGH AT LEAST EARLY SUNDAY AFTERNOON AND POSSIBLY THROUGH THE EVENING OVER WESTERN WISCONSIN. PREDICTED SNOWFALL AMOUNTS MAY BE CONSERVATIVE IF THE HIGHER QPF DEPICTIONS PAN OUT...BUT STILL EXPECTING 6 TO 9 INCHES ACROSS CENTRAL MN AND WESTERN WISCONSIN...AND 3 TO 5 INCHES NEAR THE IOWA BORDER. COULD SEE SOME ISOLATED TOTALS EXCEED 9 OR 10 INCHES IN LOCALLY FAVORED BANDING AREAS. THEREFORE...EXPANDED THE WINTER STORM WARNING SOUTH TO ABOUT A LINE FROM REDWOOD FALLS...TO RED WING..AND EAU CLAIRE WITH A WINTER WEATHER ADVISORY SOUTH OF THAT TO THE IOWA BORDER. THESE HEADLINES DEAL WITH SNOWFALL TOTALS ONLY. THE BIG CHANGE TO THIS FORECAST PACKAGE WAS TO ISSUE A BLIZZARD WARNING FROM LATE SUNDAY MORNING THROUGH SUNDAY EVENING WEST OF A LINE FROM ALEXANDRIA TO WILLMAR AND MANKATO. MODELS HAVE BEEN CONSISTENT IN SHOWING POTENTIAL FOR 40 KT WINDS WITHIN THE MIXED LAYER BEHIND THE SYSTEM AND THINK GUSTS TO AT LEAST 35 KTS WILL BE FREQUENT. COUPLE THAT WITH FRESHLY FALLEN SNOW AND POTENTIALLY ADDITIONAL LIGHT SNOW...CONFIDENCE HAS INCREASED THAT BLIZZARD CONDITIONS WILL BE COMMON WITH NEAR ZERO VISIBILITIES IN OPEN AREAS SUNDAY AFTERNOON AND EARLY EVENING /ESPECIALLY IF GUSTS EXCEED 45 MPH/. TEMPERATURES WILL PLUMMET BELOW ZERO SUNDAY EVENING AS WELL...THREATENING THE LIVES OF ANY STUCK TRAVELERS. KEPT THE BLIZZARD WARNING CONFINED TO AREAS WITH A HIGH LIKELIHOOD OF AT LEAST 4 INCHES OF SNOW WHICH IS GENERALLY NEEDED FOR CONSIDERABLE BLOWING AND DRIFTING. THE SYSTEM WILL PULL OUT SUNDAY NIGHT AS THE RIDGE QUICKLY BUILDS INTO THE WEST. SOME SNOW IS STILL POSSIBLE OVER WRN WI IN CYCLONIC FLOW...BUT CLEARING SKIES WILL ALLOW FOR A BITTER COLD NIGHT WITH LOWS IN THE TEENS BELOW OVER WRN MN AND NEAR ZERO AS FAR EAST AS I-35. WINDS SHOULD REMAIN ELEVATED ENOUGH TO BRING WIND CHILL VALUES DOWN INTO THE 20S AND POSSIBLY LOW 30S BELOW NEAR THE SOUTH DAKOTA BORDER...WITH TEENS BELOW TO I-35. WIND CHILL ADVISORIES WILL BE NEEDED AFTER THE OTHER WINTER HEADLINES EXPIRE. WILL REMAIN COLD DESPITE SUNSHINE ON MONDAY UNDER THE RIDGE AXIS...BUT RETURN FLOW MONDAY EVENING SHOULD KEEP TEMPS STEADY OR SLOWLY RISE OVERNIGHT. A WEAK SYSTEM PASSING THROUGH THE UPPER MISSISSIPPI VALLEY TUESDAY COULD BRING A LITTLE LIGHT SNOW OR FLURRIES WITH NO ACCUMULATIONS ARE EXPECTED. LONG TERM...WEDNESDAY THROUGH SATURDAY. UPPER LEVEL RIDGING WILL BE IN PLACE ACROSS THE GULF OF ALASKA BY MIDWEEK...WITH A DEEP TROUGH DIGGING DOWN THE WEST COAST. SOUTHWEST FLOW WILL STREAM ACROSS THE CENTRAL CONUS...WITH WARM AIR ADVECTION SPREADING OVERHEAD ALLOWING HIGH TEMPS TO MAKE A RUN AT THE THAWING MARK FOR BOTH WEDNESDAY AND THURSDAY. BY FRIDAY A WELL ESTABLISHED EAST/WEST TEMPERATURE GRADIENT WILL BE IN PLACE OVER THE UPPER MIDWEST...AND THE AFOREMENTIONED WEST COAST TROUGH WILL MOVE INLAND OVER THE FOUR CORNERS REGION. THIS WILL BE THE MAIN PLAYER IN THE WEEKEND WEATHER AS BOTH THE GFS AND ECMWF 08.12 EJECT THIS WAVE TOWARDS THE GREAT LAKES REGION. THIS PV ANOMALY WILL ACT ON THE LOW LEVEL TEMPERATURE GRADIENT AND CAUSE A SURFACE CYCLONE TO DEVELOP AND TRACK SOUTH AND EAST OF THE CWA. THIS WOULD PUT CENTRAL MINNESOTA AND WESTERN WISCONSIN IN A FAVORABLE REGION FOR ANOTHER POTENTIAL WEEKEND SNOW STORM. FORECAST SOUNDINGS AND NORTH/SOUTH CROSS SECTIONS VIA THE GFS SHOW A WARM LAYER CENTERED AROUND H850 WITH THE 0C LINE EXTENDING AS FAR NORTH AS THE METRO AREA. THEREFORE HAVE INCLUDED THE CHANCE OF MIXED PRECIP FOR SATURDAY MORNING ACROSS THE SOUTHEAST HALF OF THE CWA WITH THE INITIAL SURGE OF LOW LEVEL THETA_E ADVECTION...AND THEN TRANSITION TO ALL SNOW BY THE AFTERNOON. ALSO INCREASED POPS ABOVE GUIDANCE GIVEN THE REMARKABLE AGREEMENT BY THE LONG RANGE MODELS. && .AVIATION.../06Z TAF ISSUANCE/ SIGNIFICANT SOUTHERN SHIFT ALONG WITH A BIT OF A SLOWING OCCURRED WITH 00Z MODEL RUNS AND THIS PLACES ALL MPX TERMINALS WITHIN THE HEART OF WHAT LOOKS TO BE AN IMPRESSIVE SNOW BAND...WITH 6-10 INCH SNOW TOTALS /AND POSSIBLY MORE AT STC...MSP...RNH/ NOW EXPECTED. SFC LOW RIGHT NOW IS CENTERED ALONG I-90 NEAR CHAMBERLAIN...SD. 00Z NAM/GFS ALONG WITH THE RAP TRACK THIS LOW RIGHT DOWN I-90 THROUGH THE DAY SUNDAY...PLACING THE MPX TERMINALS WITHIN THE HEAVIEST SNOW. HAVE ALREADY BEEN GETTING SNOWFALL RATES OF AN INCH PLUS PER HOUR IN WRN MN...SO CONTINUED TO ADVERTISE PROLONGED PERIODS OF 1/2SM VIS AT ALL TERMINALS...BUT TENDED TO SHIFT THAT MENTION OUT IN TIME WITH THE SLOWING. ANOTHER ASPECT OF THE SLOWING WAS THE NEED TO SLOW THE BACKING OF WINDS FROM THE EAST OVER TO THE NW...ALONG WITH A TEMPERING OF SPEEDS SOME...AS NAM NOW SHOWING GUST POTENTIAL GREATER THAN 35 KTS AT ONLY RWF. AS THIS TAF PERIOD COMES TO AN END...CLEARING WILL START WORKING INTO WRN MN...WITH VFR CONDITIONS EXPECTED AS WE START GOING A LITTLE BEYOND THIS TAF PERIOD. KMSP...ALL GUIDANCE NOW PUTTING MSP IN THE CROSS-HAIRS FOR THE HEAVIEST SNOW WITH THIS EVENT...SO SIGNIFICANTLY DEGRADED TAF...WITH LIFR VIS SNOW NOW EXTENDING WELL OUT INTO THE AFTERNOON. LOOKING AT THE NAM ALONG WITH CURRENT RADAR...EXPECTING TWO BURSTS OF SNOW THIS PERIOD. FIRST WILL COME BETWEEN 8Z AND 12Z AS WARM ADVECTIVE WING OF PRECIP SWINGS THROUGH...WITH THE NEXT...MORE PROLONGED BOUT OF HEAVY SNOW HITTING BETWEEN 14Z AND 22Z AS THE MAIN UPPER FORCING MOVES IN. THIS IS WHEN MAJORITY OF ACCUMULATIONS SHOULD OCCUR...WITH SEVERAL OF THESE HOURS LIKELY SEEING RATES AROUND 1 INCH AN HOUR. THIS TAF MAY A BIT PESSIMISTIC WITH THE LENGTH OF 1/2SM VIS...BUT FEEL PRETTY CONFIDENT IN WINDOWS OF HEAVIER SNOW THAT ARE INDICATED WITH TAF. AVIATION WEATHER WARNING WILL ALSO BE ISSUED SHORTLY FOR ACCUMULATIONS EXCEEDING 3/4 OF AN INCH PER HOUR. AS FOR STORM TOTAL...WOULD PUT MSP ON THE HIGHER END OF THE SCALE WITH 8-10 INCHES LOOKING MORE AND MORE LIKELY. /OUTLOOK FOR KMSP/ MON...MVFR/IFR CIGS POSSIBLE EARLY. THEN VFR. WINDS WNW AT 10G15KTS. TUE...MVFR/IFR CIGS POSSIBLE. WINDS SW AT 10G15KTS. WED...VFR. WINDS SE AT 10KTS. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...WINTER WEATHER ADVISORY UNTIL MIDNIGHT CST SUNDAY NIGHT FOR BLUE EARTH-FARIBAULT-FREEBORN-GOODHUE-LE SUEUR-RICE-STEELE- WASECA. WINTER STORM WARNING UNTIL 11 AM CST SUNDAY FOR CHIPPEWA-DOUGLAS- KANDIYOHI-LAC QUI PARLE-POPE-RENVILLE-SIBLEY-STEVENS-SWIFT- YELLOW MEDICINE. BLIZZARD WARNING FROM 11 AM SUNDAY TO MIDNIGHT CST SUNDAY NIGHT FOR BROWN-CHIPPEWA-DOUGLAS-KANDIYOHI-LAC QUI PARLE-NICOLLET- POPE-REDWOOD-RENVILLE-SIBLEY-STEVENS-SWIFT-YELLOW MEDICINE. WINTER STORM WARNING UNTIL MIDNIGHT CST SUNDAY NIGHT FOR BENTON- CHISAGO-ISANTI-KANABEC-MCLEOD-MEEKER-MILLE LACS-MORRISON- SHERBURNE-STEARNS-TODD-WRIGHT. WINTER STORM WARNING UNTIL MIDNIGHT CST SUNDAY NIGHT FOR ANOKA- CARVER-DAKOTA-HENNEPIN-RAMSEY-SCOTT-WASHINGTON. WINTER WEATHER ADVISORY UNTIL MIDNIGHT CST SUNDAY NIGHT FOR MARTIN-WATONWAN. WINTER WEATHER ADVISORY UNTIL 11 AM CST SUNDAY FOR BROWN- NICOLLET-REDWOOD. WI...WINTER STORM WARNING UNTIL MIDNIGHT CST SUNDAY NIGHT FOR BARRON- CHIPPEWA-DUNN-EAU CLAIRE-PEPIN-PIERCE-POLK-RUSK-ST. CROIX. && $$ BORGHOFF/MPG
AREA FORECAST DISCUSSION...UPDATED AVIATION
NWS ST LOUIS MO
1117 PM CST SAT DEC 8 2012 .UPDATE... ISSUED AT 849 PM CST SAT DEC 8 2012 MUCH OF THE CWA HAS BEEN DRY SO FAR THIS EVENING WITH LOW CLOUDS AND SOME PATCHY FOG. STILL BELIEVE THAT RAIN CHANCES WILL INCREASE SIGNIFICANTLY LATER THIS EVENING AND OVER NIGHT AS LARGE SCALE ASCENT INCREASES AHEAD OF SHORTWAVE MOVING ACROSS THE CENTRAL PLAINS. RAP HAS BEEN CONSISTENT IN SHOWING AN INCREASE IN LOW LEVEL MOISTURE CONVERGENCE ALONG 850MB WARM FRONT TONIGHT. ONLY CHANGE IN FORECAST IS TO REFLECT NEAR TERM PRECIPITATION AND TEMPERATURE TRENDS. BRITT && .SHORT TERM... ISSUED AT 213 PM CST SAT DEC 8 2012 (TONIGHT) SHORTWAVE DIVING THROUGH EASTERN MONTANA AT THIS TIME IS FORCING CYCLOGENESIS OVER THE NORTHERN PLAINS. SOUTHWESTERLY LOW LEVEL FLOW WILL BEGIN TO INCREASE OVER THE LOWER MISSISSIPPI VALLEY TONIGHT IN RESPONSE TO THE STRENGTHENING LOW. THIS WILL BRING THE QUASI-STATIONARY FRONT HANGING OVER ARKANSAS BACK NORTH INTO OUR AREA BY EARLY SUNDAY MORNING. LOW LEVEL JET RAMPS UP AROUND 30KTS THIS EVENING PRODUCING DECENT 850MB MOISTURE CONVERGENCE OVER THE AREA. AT FIRST IT`S RATHER WEAK AND DIFFUSE...BUT BECOMES STRONGER OVER NORTHEAST MISSOURI AND WEST CENTRAL ILLINOIS LATE TONIGHT AS THE 850MB TEMP GRADIENT TIGHTENS UP. EXPECT WIDELY SCATTERED SHOWERS TO DEVELOP THIS EVENING OVER SOUTHEAST MISSOURI...OVERSPREADING THE ENTIRE AREA AND INCREASING IN AREAL COVERAGE IN RESPONSE TO THE INCREASING MOISTURE CONVERGENCE. COULD SEE A LITTLE THUNDER AS WELL...PRIMARILY OVER SOUTHEAST MISSOURI AND SOUTHERN ILLINOIS WHERE MUCAPE IS FORECAST TO EXCEED 250 J/KG. TEMPERATURES WILL TAKE AN INITIAL DIP THIS EVENING...BUT SHOULD LEVEL OUT AND POSSIBLY RISE SLIGHTLY AS THE WARM FRONT MOVES UP INTO THE BI-STATE REGION LATE TONIGHT. CARNEY && .LONG TERM... ISSUED AT 213 PM CST SAT DEC 8 2012 SUNDAY AND SUNDAY NIGHT... THE WARM FRONTAL BOUNDARY WILL BE LOCATED ACROSS THE SOUTHERN PORTION OF THE CWA BY 12Z...WITH THE OVERNIGHT WARM ADVECTION PRECIPITATION BEGINNING TO LIFT NORTH AND EAST OF THE CWA. THINK THERE WILL BE A LULL IN THE RAIN BY MIDMORNING ACROSS A GOOD AMOUNT OF THE CWA UNTIL A STRONG COLD FRONT MOVES SOUTHEAST ACROSS THE AREA IN THE AFTERNOON AND EVENING. THIS FRONT WILL REINFORCE THE BAROCLINICITY TO OUR SOUTHEAST AND LEAD TO LIGHT RAIN REDEVELOPING ACROSS AT LEAST THE SOUTHEAST HALF OF THE CWA FOR THE AFTERNOON AND EARLY EVENING HOURS. LUCKILY...ALL INDICATIONS ARE THAT THE RAIN WILL TURN TO COLD SUNDAY NIGHT AS DEEP MOISTURE IS SHUNTED TO THE SOUTHEAST AS THE WINTER BLAST ARRIVES AND COLD AIR DEEPENS ACROSS THE CWA. MONDAY THROUGH THURSDAY... A RAW WINTER DAY IS ON TAP FOR MONDAY AS TEMPERATURES STRUGGLE TO RISE BACK ABOVE FREEZING WITH STRONG COLD ADVECTION AND A GUSTY NORTHWEST WIND. THE WINTER CHILL SHOULD BE BRIEF THOUGH...AS TEMPERATURES WILL ALREADY BEGIN MODERATING BY MIDWEEK DESPITE A TROF MOVING ACROSS THE MIDWEST. TEMPERATURES WILL RISE BACK ABOVE NORMAL FOR THE END OF THE WEEK AS THE UPPER FLOW BECOMES SOUTHWEST IN RESPONSE TO A STRONG STORM SYSTEM DIGGING SOUTH ALONG THE WEST COAST. FRIDAY THROUGH SATURDAY... NEARLY ALL OF THE MEDIUM RANGE GUIDANCE DEPICTS A STRONG SHORTWAVE AND SURFACE LOW PASSING TO THE WEST OF THE CWA FRIDAY NIGHT. THIS PATTERN IS INDICATIVE OF ABOVE NORMAL TEMPERATURES AND A GOOD CHANCE OF SHOWERS AND THUNDERSTORMS. CVKING && .AVIATION... ISSUED AT 1033 PM CST SAT DEC 8 2012 STRATUS CLOUDS WERE SLOWLY LOWERING THIS EVNG...EXCEPT AT UIN WHERE RAIN DEVELOPED AND CAUSED THE CEILINGS TO TEMPORARILY RISE. THE CEILING AT UIN SHOULD LOWER AGAIN LATE TGT BEFORE THE NEXT ROUND OF RAIN MOVES IN. MORE LIGHT RAIN WILL DEVELOP LATE TGT AS THE STATIONARY FRONT ACROSS NRN AR LIFTS BACK NWD INTO SRN MO AND A SWLY LOW LEVEL JET BRINGS INCREASING AND DEEPENING LOW LEVEL MOISTURE INTO THE AREA. CEILINGS WILL LIKELY LOWER TO 500 TO 1000 FT WITH VSBYS OF 2-4SM IN LIGHT RAIN AND FOG. E-SELY SFC WIND WILL CONTINUE LATE TGT. THE RAIN SHOULD END IN UIN AND COU BY LATE SUN MRNG AS A SFC WAVE ALONG THE FRONT MOVES E OF THE AREA...WHILE A STRONG COLD FRONT DROPS SEWD INTO THE REGION. RAIN WILL LIKELY CONTINUE IN THE ST LOUIS METRO AREA SUN AFTN UNTIL THE COLD FRONT MOVES SE OF THE AREA WITH CAA AND DRYING OF THE LOW LEVELS BEHIND THE COLD FRONT. THE SFC WIND WILL VEER AROUND TO A NWLY DIRECTION AS THE SFC WAVE SHIFTS E OF THE AREA...AND THEN STRENGTHENS AFTER PASSAGE OF THE STRONG COLD FRONT SUN AFTN. WILL SEE AN IMPROVEMENT IN VSBYS LATE SUN MRNG AND AFTN...BUT ONLY A VERY GRADUAL RISE IN CEILING HEIGHTS WITH CIGS RISING TO AROUND 1000 FT BY EARLY AFTN. THE CEILING WILL CONTINUE TO RISE...INTO THE MVFR CATAGORY BY LATE AFTN AND TO THE VFR CATAGORY SUN EVNG. SPECIFICS FOR KSTL...CIG HEIGHTS SHOULD CONTINUE TO LOWER LATE TGT WITH FOG DEVELOPING. THE CIGS SHOULD LOWER TO AROUND 500-1000 FT LATE TGT WITH VSBYS FALLING TO AROUND 2-4SM AS LIGHT RAIN MOVES INTO THE AREA. AN E-SELY SFC WIND WILL CONTINUE LATE TGT AS A SFC RIDGE SHIFTS WELL NE OF OUR AREA WHILE A WARM FRONT APPROACHES STL FROM THE S. THE RAIN SHOULD END BY SUN EVNG AS A SFC WAVE ALONG THIS FRONT SHIFTS WELL NE OF STL AND A STRONG COLD FRONT MOVES SE OF STL CAUSING THE SFC WIND TO VEER AROUND TO A W-NWLY DIRECTION AND STRENGTHEN DURING THE AFTN AND EVNG HOURS. THE VSBYS WILL IMPROVE DURING THE LATE MRNG AND AFTN HOURS WITH THE CLOUD CEILING RISING TO AROUND 1000 FT BY AFTN AND 1500 FT BY SUN EVNG. THE CEILING SHOULD FINALY RISE INTO THE VFR CATAGORY LATE SUN NGT. GKS && .LSX WATCHES/WARNINGS/ADVISORIES... MO...NONE. IL...NONE. && $$ WFO LSX
AREA FORECAST DISCUSSION
NWS NORTH PLATTE NE
1120 PM CST SAT DEC 8 2012 .AVIATION...FOR THE KLBF AND KVTN TERMINALS THROUGH 06Z MONDAY. AN UPPER LEVEL TROUGH OF LOW PRESSURE WILL TRACK ACROSS THE CENTRAL AND NORTHERN PLAINS OVER THE NEXT 24 HOURS...LEADING TO ABUNDANT CLOUDINESS AND WINDY CONDITIONS ACROSS WESTERN AND NORTH CENTRAL NEBRASKA THROUGH SUNDAY AFTERNOON. AT THE KLBF TERMINAL...EXPECT CIGS AON 10000 FT AGL THROUGH 13Z SUNDAY MORNING...DROPPING DOWN TO AROUND 3000 FT AGL. CIGS WILL BEGIN TO SCATTER OUT AFTER 22Z SUNDAY...CLEARING OUT SUNDAY EVENING. AT THE KVTN TERMINAL...LIGHT SNOW IS EXPECTED OVER THE NEXT 2 TO 4 HOURS...AND IS EXPECTED TO EXIT THE TERMINAL AFTER 10Z SUNDAY. CIGS WILL REMAIN AON 1500 FT AGL THROUGH SUNDAY MORNING...RISING TO 2500 FT AGL. SKIES WILL SCATTER OUT SUNDAY AFTERNOON...CLEARING SUNDAY EVENING. STRONG NORTHERLY WINDS OF 20 TO 25 KTS...WITH GUSTS UP TO 33 KTS ARE LIKELY FOR THE REST OF TONIGHT THROUGH SUNDAY AFTERNOON. WINDS WILL QUICKLY DIMINISH SUNDAY EVENING AFTER SUNDOWN. && .PREV DISCUSSION... /ISSUED 1009 PM CST SAT DEC 8 2012/ UPDATE...BASED ON PRESSURE TRENDS ACROSS EASTERN SOUTH DAKOTA AND THE LATEST NAM AND MAV GUIDANCE...DECIDED TO HOIST A WIND ADVISORY FOR SUNDAY MORNING THROUGH SUNDAY AFTERNOON ACROSS A LARGE PORTION OF NORTH CENTRAL AND CENTRAL NEBRASKA. STRONG PRESSURE RISES OF 3 TO 6 MB/3HR WILL TRACK FROM NORTH CENTRAL NEBRASKA INTO NORTHEASTERN NEBRASKA FROM 12Z THROUGH 18Z SUNDAY. WINDS WILL PEAK AROUND NOON TIME...THEN SLOWLY DECLINE INTO THE LATE AFTERNOON HOURS. IN ADDITION TO STRONG WINDS...HIGHS SUNDAY WILL BE IN THE TEENS AND 20S...PRODUCING WIND CHILLS OF ZERO TO MINUS 10 IN THE ADVISORY AREA. STILL WELL ABOVE CRITERIA FOR A WIND CHILL ADVISORY...BUT WORTH MENTIONING IN THE HWO AND NPW/WIND ADVISORY PRODUCT. BULK OF THE SNOW WILL REMAIN NORTH OF THE BORDER OVERNIGHT WITH ONLY A DUSTING EXPECTED ALONG THE NEBR/SD BORDER. && .PREV DISCUSSION... /ISSUED 606 PM CST SAT DEC 8 2012/ AVIATION...FOR THE KLBF AND KVTN TERMINALS THROUGH 00Z MONDAY. AN UPPER LEVEL TROUGH OF LOW PRESSURE WILL TRACK ACROSS THE CENTRAL AND NORTHERN PLAINS OVER THE NEXT 24 HOURS...LEADING TO ABUNDANT CLOUDINESS AND WINDY CONDITIONS ACROSS WESTERN AND NORTH CENTRAL NEBRASKA. AT THE KLBF TERMINAL...EXPECT CIGS AON 10000 FT AGL THROUGH 10Z TONIGHT...DROPPING DOWN TO AROUND 4000 FT AGL. CIGS WILL BEGIN TO SCATTER OUT AFTER 17Z SATURDAY. AT THE KVTN TERMINAL...CIGS WILL DROP FROM 5000 FT AGL DOWN TO 1500 FT AGL OVERNIGHT AND REMAIN THERE THROUGH MIDDAY SUNDAY. SKIES WILL BEGIN TO SCATTER OUT BY LATE AFTERNOON. FOR BOTH TERMINALS...LOOK FOR NORTHERLY WINDS TO INCREASE TO 15 TO 25 KTS TONIGHT WITH PERIODIC GUSTS TO AROUND 30 KTS AT BOTH TERMINALS. WINDS WILL GRADUALLY DIMINISH LATE SUNDAY AFTERNOON. && .PREV DISCUSSION... /ISSUED 244 PM CST SAT DEC 8 2012/ ...MUCH COLDER WITH WINDY CONDITIONS LATE TONIGHT AND SUNDAY... SYNOPSIS... SURFACE LOW PRESSURE RESIDES ACROSS THE CENTRAL HIGH PLAINS WITH MAIN LOW FORMING NEAR PINE RIDGE SOUTH DAKOTA. LEADING EDGE OF COLD FRONT JUST PASSED CHADRON. STEEP LAPSE RATES ATTRIBUTING TO CONVECTIVE SNOW SHOWERS PANHANDLE INTO NORTH CENTRAL. MUCH OF RADAR ECHOES NOT REACHING GROUND EFFECTIVELY DUE TO FAIRLY LARGE TEMPERATURES AND DEWPOINT SPREAD. NEVERTHELESS... THIS HAS BEEN MOISTENING UP THE ATMOSPHERE FOR UPSTREAM DEVELOPMENT TO TAKE ADVANTAGE OF FOR LATE AFTERNOON INTO THIS EVENING. DISCUSSION... SHORT TERM...TONIGHT THROUGH TUESDAY. MAIN FORECAST CONCERNS OVER THE NEXT 36 HOURS INVOLVES THE THREAT OF LIGHT SNOW...A RETURN OF COLD TEMPERATURES...AND THE POTENTIAL OF ADVISORY CRITERIA WIND SPEEDS. MODELS CONTINUE TO SHOW GOOD AGREEMENT IN THE NEAR TERM IN WHICH THE SHORTWAVE TROUGH CURRENTLY LOCATED FROM CENTRAL SOUTH DAKOTA INTO EASTERN MONTANA AND ASSOCIATED SURFACE LOW DEEPEN AND EJECT EAST ACROSS THE NORTHERN PLAINS...DRAGGING A STRONG COLD FRONT THROUGH THE CWA OVERNIGHT TONIGHT. THE RAP MODEL CONTINUES TO INDICATE THE SURFACE LOW NEAR AND SOUTH OF I90 TONIGHT WHICH REMAINS FARTHER SOUTH THAN OTHER SHORT TERM MODELS. AN H3 JET MAX ACROSS NORTHERN COLORADO AND SOUTHERN NEBRASKA THIS EVENING WILL BE FAVORABLE FOR ASCENT IN THE LEFT EXIT REGION OF JET ACROSS NORTH CENTRAL NEBRASKA. AS SUGGESTED BY THE RAP MODEL...REGIONAL GEM AND TO A LESSER EXTEND THE NAM...BANDED SNOWFALL IS FAVORABLE FROM NEAR MULLEN THROUGH BASSETT. LOCAL SNOWFALL AMOUNTS NEAR AN INCH POSSIBLE IN THESE BANDED AREAS. OTHERWISE...LIGHT SNOW ALSO FORECAST TO DEVELOP AND DROP SOUTH INTO FAR NORTHERN NEBRASKA LATE TONIGHT INTO SUNDAY MORNING. THIS IS WITHIN SOUTHERN PERIPHERY OF DEFORMATION ZONE TO BE ACROSS EASTERN SOUTH DAKOTA INTO SOUTH CENTRAL SOUTH DAKOTA. ANY ASSOCIATED SNOWFALL WOULD REMAIN A HALF INCH OR LESS. ACROSS THE SOUTHERN HALF OF FORECAST AREA...ANY LINGERING SNOW OR FLURRIES FROM THIS EVENING SHOULD END SOON AFTER MIDNIGHT. STRONG COLD AIR ADVECTION AND LOW LEVEL PRESSURE RISES WILL FOLLOW THE SURFACE BOUNDARY PASSAGE OVERNIGHT TONIGHT. THE PRESSURE RISES WILL HELP TIGHTEN THE SURFACE GRADIENT AND ALLOW FOR GUSTY CONDITIONS LATER TONIGHT INTO SUNDAY. THE MODELS HAVE SHOWN A SLIGHT SOUTHWARD TREND IN THE TRACK OF THE SURFACE LOW...NOW ACROSS FAR SOUTHWEST MINNESOTA. THIS TRACK FAVORS SLIGHTLY STRONGER SURFACE WINDS THAN PREVIOUSLY ANTICIPATED. WILL KEEP WIND SPEEDS JUST BELOW ADVISORY CRITERIA...ESPECIALLY SINCE THE STRONGEST PRESSURE RISES ARE EXPECTED DURING THE EARLY MORNING HOURS...DIURNALLY UNFAVORABLE FOR ADVISORY CRITERIA WIND. BUT...WIDESPREAD SUB ZERO WIND CHILLS WILL OCCUR...WITH THE POTENTIAL OF SOME OF THE LOWEST READINGS APPROACHING MINUS TEN OR COLDER THROUGH SUNDAY MORNING ACROSS OUR NORTHERN ZONES. HIGHS ON SUNDAY WILL BE COLD...WITH READINGS TRENDED DOWN TO NEAR 15 AT VALENTINE TO THE MID 20S FAR SOUTH. WE WILL NEED TO WATCH LOW TEMPERATURES FOR MONDAY MORNING...AS ANY SNOWFALL WOULD ALLOW READINGS TO PLUMMET...TO POSSIBLY BELOW ZERO. CURRENT FORECAST HAS LOWS 1 TO 5 ABOVE MOST AREAS...AS WIDESPREAD ACCUMULATING SNOW IS NOT ANTICIPATED. TEMPERATURES BEGIN TO MODERATE SLOWLY MONDAY AFTERNOON AS WEAK WAA INFILTRATES FROM THE WEST IN ADVANCE OF THE NEXT SHORTWAVE TROUGH. HIGHS TO RANGE IN THE 30S. THEN A WESTERLY DOWNSLOPE TUESDAY TO WARM READINGS TO THE MID 30S TO LOWER 40S. LONG TERM...TUESDAY NIGHT THROUGH SATURDAY. SHORTWAVE RIDGING AND WAA TAKE HOLD WEDNESDAY THROUGH THURSDAY...WITH TEMPERATURES SLIGHTLY ABOVE SEASONAL NORMS WEDNESDAY AND NEAR NORMAL THURSDAY. WILL NEED TO MONITOR IF A BACK DOOR COLD FRONT DROPS INTO NORTH CENTRAL NEBRASKA THURSDAY. THE ECMWF AND GEM KEEP COLDER AIR TO THE NORTH INTO SOUTH DAKOTA...WHILE THE GFS BRINGS IT SOUTH INTO NORTHERN NEBRASKA. THE NEXT SIGNIFICANT TROUGH IS SHOWN TO REACH THE FOUR CORNERS REGION 12Z FRIDAY AND TRACK INTO NORTHWEST MISSOURI AS A NEGATIVELY TILTED CLOSED LOW BY 12Z SATURDAY PER THE ECMWF SOLUTION. THE GFS ALSO INDICATES A NEGATIVELY TILTED TROUGH...ALTHOUGH AS AN OPEN WAVE FROM WESTERN SOUTH DAKOTA INTO NORTHERN NEBRASKA. PRECIPITATION CHANCES NOW BROUGHT INTO EASTERN NEBRASKA FRIDAY NIGHT INCLUDING FAR EASTERN PORTIONS OF NORTH CENTRAL NEBRASKA. HIGHS FRIDAY FORECAST TO RANGE IN THE 30S AND MID 30S TO LOW 40S SATURDAY. && .LBF WATCHES/WARNINGS/ADVISORIES...WIND ADVISORY IN EFFECT FROM 4 AM CST SUNDAY MORNING THROUGH 5 PM CST SUNDAY AFTERNOON FOR ZONES NEZ005>010-025>029-037-038. && $$ SHORT TERM/EXTENDED...ROBERG AVIATION AND UPDATE...BUTTLER
AREA FORECAST DISCUSSION
NWS NORTH PLATTE NE
1009 PM CST SAT DEC 8 2012 .UPDATE...BASED ON PRESSURE TRENDS ACROSS EASTERN SOUTH DAKOTA AND THE LATEST NAM AND MAV GUIDANCE...DECIDED TO HOIST A WIND ADVISORY FOR SUNDAY MORNING THROUGH SUNDAY AFTERNOON ACROSS A LARGE PORTION OF NORTH CENTRAL AND CENTRAL NEBRASKA. STRONG PRESSURE RISES OF 3 TO 6 MB/3HR WILL TRACK FROM NORTH CENTRAL NEBRASKA INTO NORTHEASTERN NEBRASKA FROM 12Z THROUGH 18Z SUNDAY. WINDS WILL PEAK AROUND NOON TIME...THEN SLOWLY DECLINE INTO THE LATE AFTERNOON HOURS. IN ADDITION TO STRONG WINDS...HIGHS SUNDAY WILL BE IN THE TEENS AND 20S...PRODUCING WIND CHILLS OF ZERO TO MINUS 10 IN THE ADVISORY AREA. STILL WELL ABOVE CRITERIA FOR A WIND CHILL ADVISORY...BUT WORTH MENTIONING IN THE HWO AND NPW/WIND ADVISORY PRODUCT. BULK OF THE SNOW WILL REMAIN NORTH OF THE BORDER OVERNIGHT WITH ONLY A DUSTING EXPECTED ALONG THE NEBR/SD BORDER. && .PREV DISCUSSION... /ISSUED 606 PM CST SAT DEC 8 2012/ AVIATION...FOR THE KLBF AND KVTN TERMINALS THROUGH 00Z MONDAY. AN UPPER LEVEL TROUGH OF LOW PRESSURE WILL TRACK ACROSS THE CENTRAL AND NORTHERN PLAINS OVER THE NEXT 24 HOURS...LEADING TO ABUNDANT CLOUDINESS AND WINDY CONDITIONS ACROSS WESTERN AND NORTH CENTRAL NEBRASKA. AT THE KLBF TERMINAL...EXPECT CIGS AON 10000 FT AGL THROUGH 10Z TONIGHT...DROPPING DOWN TO AROUND 4000 FT AGL. CIGS WILL BEGIN TO SCATTER OUT AFTER 17Z SATURDAY. AT THE KVTN TERMINAL...CIGS WILL DROP FROM 5000 FT AGL DOWN TO 1500 FT AGL OVERNIGHT AND REMAIN THERE THROUGH MIDDAY SUNDAY. SKIES WILL BEGIN TO SCATTER OUT BY LATE AFTERNOON. FOR BOTH TERMINALS...LOOK FOR NORTHERLY WINDS TO INCREASE TO 15 TO 25 KTS TONIGHT WITH PERIODIC GUSTS TO AROUND 30 KTS AT BOTH TERMINALS. WINDS WILL GRADUALLY DIMINISH LATE SUNDAY AFTERNOON. && .PREV DISCUSSION... /ISSUED 244 PM CST SAT DEC 8 2012/ ...MUCH COLDER WITH WINDY CONDITIONS LATE TONIGHT AND SUNDAY... SYNOPSIS... SURFACE LOW PRESSURE RESIDES ACROSS THE CENTRAL HIGH PLAINS WITH MAIN LOW FORMING NEAR PINE RIDGE SOUTH DAKOTA. LEADING EDGE OF COLD FRONT JUST PASSED CHADRON. STEEP LAPSE RATES ATTRIBUTING TO CONVECTIVE SNOW SHOWERS PANHANDLE INTO NORTH CENTRAL. MUCH OF RADAR ECHOES NOT REACHING GROUND EFFECTIVELY DUE TO FAIRLY LARGE TEMPERATURES AND DEWPOINT SPREAD. NEVERTHELESS... THIS HAS BEEN MOISTENING UP THE ATMOSPHERE FOR UPSTREAM DEVELOPMENT TO TAKE ADVANTAGE OF FOR LATE AFTERNOON INTO THIS EVENING. DISCUSSION... SHORT TERM...TONIGHT THROUGH TUESDAY. MAIN FORECAST CONCERNS OVER THE NEXT 36 HOURS INVOLVES THE THREAT OF LIGHT SNOW...A RETURN OF COLD TEMPERATURES...AND THE POTENTIAL OF ADVISORY CRITERIA WIND SPEEDS. MODELS CONTINUE TO SHOW GOOD AGREEMENT IN THE NEAR TERM IN WHICH THE SHORTWAVE TROUGH CURRENTLY LOCATED FROM CENTRAL SOUTH DAKOTA INTO EASTERN MONTANA AND ASSOCIATED SURFACE LOW DEEPEN AND EJECT EAST ACROSS THE NORTHERN PLAINS...DRAGGING A STRONG COLD FRONT THROUGH THE CWA OVERNIGHT TONIGHT. THE RAP MODEL CONTINUES TO INDICATE THE SURFACE LOW NEAR AND SOUTH OF I90 TONIGHT WHICH REMAINS FARTHER SOUTH THAN OTHER SHORT TERM MODELS. AN H3 JET MAX ACROSS NORTHERN COLORADO AND SOUTHERN NEBRASKA THIS EVENING WILL BE FAVORABLE FOR ASCENT IN THE LEFT EXIT REGION OF JET ACROSS NORTH CENTRAL NEBRASKA. AS SUGGESTED BY THE RAP MODEL...REGIONAL GEM AND TO A LESSER EXTEND THE NAM...BANDED SNOWFALL IS FAVORABLE FROM NEAR MULLEN THROUGH BASSETT. LOCAL SNOWFALL AMOUNTS NEAR AN INCH POSSIBLE IN THESE BANDED AREAS. OTHERWISE...LIGHT SNOW ALSO FORECAST TO DEVELOP AND DROP SOUTH INTO FAR NORTHERN NEBRASKA LATE TONIGHT INTO SUNDAY MORNING. THIS IS WITHIN SOUTHERN PERIPHERY OF DEFORMATION ZONE TO BE ACROSS EASTERN SOUTH DAKOTA INTO SOUTH CENTRAL SOUTH DAKOTA. ANY ASSOCIATED SNOWFALL WOULD REMAIN A HALF INCH OR LESS. ACROSS THE SOUTHERN HALF OF FORECAST AREA...ANY LINGERING SNOW OR FLURRIES FROM THIS EVENING SHOULD END SOON AFTER MIDNIGHT. STRONG COLD AIR ADVECTION AND LOW LEVEL PRESSURE RISES WILL FOLLOW THE SURFACE BOUNDARY PASSAGE OVERNIGHT TONIGHT. THE PRESSURE RISES WILL HELP TIGHTEN THE SURFACE GRADIENT AND ALLOW FOR GUSTY CONDITIONS LATER TONIGHT INTO SUNDAY. THE MODELS HAVE SHOWN A SLIGHT SOUTHWARD TREND IN THE TRACK OF THE SURFACE LOW...NOW ACROSS FAR SOUTHWEST MINNESOTA. THIS TRACK FAVORS SLIGHTLY STRONGER SURFACE WINDS THAN PREVIOUSLY ANTICIPATED. WILL KEEP WIND SPEEDS JUST BELOW ADVISORY CRITERIA...ESPECIALLY SINCE THE STRONGEST PRESSURE RISES ARE EXPECTED DURING THE EARLY MORNING HOURS...DIURNALLY UNFAVORABLE FOR ADVISORY CRITERIA WIND. BUT...WIDESPREAD SUB ZERO WIND CHILLS WILL OCCUR...WITH THE POTENTIAL OF SOME OF THE LOWEST READINGS APPROACHING MINUS TEN OR COLDER THROUGH SUNDAY MORNING ACROSS OUR NORTHERN ZONES. HIGHS ON SUNDAY WILL BE COLD...WITH READINGS TRENDED DOWN TO NEAR 15 AT VALENTINE TO THE MID 20S FAR SOUTH. WE WILL NEED TO WATCH LOW TEMPERATURES FOR MONDAY MORNING...AS ANY SNOWFALL WOULD ALLOW READINGS TO PLUMMET...TO POSSIBLY BELOW ZERO. CURRENT FORECAST HAS LOWS 1 TO 5 ABOVE MOST AREAS...AS WIDESPREAD ACCUMULATING SNOW IS NOT ANTICIPATED. TEMPERATURES BEGIN TO MODERATE SLOWLY MONDAY AFTERNOON AS WEAK WAA INFILTRATES FROM THE WEST IN ADVANCE OF THE NEXT SHORTWAVE TROUGH. HIGHS TO RANGE IN THE 30S. THEN A WESTERLY DOWNSLOPE TUESDAY TO WARM READINGS TO THE MID 30S TO LOWER 40S. LONG TERM...TUESDAY NIGHT THROUGH SATURDAY. SHORTWAVE RIDGING AND WAA TAKE HOLD WEDNESDAY THROUGH THURSDAY...WITH TEMPERATURES SLIGHTLY ABOVE SEASONAL NORMS WEDNESDAY AND NEAR NORMAL THURSDAY. WILL NEED TO MONITOR IF A BACK DOOR COLD FRONT DROPS INTO NORTH CENTRAL NEBRASKA THURSDAY. THE ECMWF AND GEM KEEP COLDER AIR TO THE NORTH INTO SOUTH DAKOTA...WHILE THE GFS BRINGS IT SOUTH INTO NORTHERN NEBRASKA. THE NEXT SIGNIFICANT TROUGH IS SHOWN TO REACH THE FOUR CORNERS REGION 12Z FRIDAY AND TRACK INTO NORTHWEST MISSOURI AS A NEGATIVELY TILTED CLOSED LOW BY 12Z SATURDAY PER THE ECMWF SOLUTION. THE GFS ALSO INDICATES A NEGATIVELY TILTED TROUGH...ALTHOUGH AS AN OPEN WAVE FROM WESTERN SOUTH DAKOTA INTO NORTHERN NEBRASKA. PRECIPITATION CHANCES NOW BROUGHT INTO EASTERN NEBRASKA FRIDAY NIGHT INCLUDING FAR EASTERN PORTIONS OF NORTH CENTRAL NEBRASKA. HIGHS FRIDAY FORECAST TO RANGE IN THE 30S AND MID 30S TO LOW 40S SATURDAY. && .LBF WATCHES/WARNINGS/ADVISORIES...WIND ADVISORY IN EFFECT FROM 4 AM CST SUNDAY MORNING THROUGH 5 PM CST SUNDAY AFTERNOON FOR ZONES NEZ005>010-025>029-037-038. && $$ SHORT TERM/EXTENDED...ROBERG AVIATION AND UPDATE...BUTTLER
AREA FORECAST DISCUSSION
NWS RALEIGH NC
255 AM EST SUN DEC 9 2012 .SYNOPSIS... A WARM MOIST SOUTHERLY FLOW AHEAD OF AN APPROACHING COLD FRONT WILL RESULT IN ABOVE NORMAL TEMPERATURES THROUGH MONDAY. THE COLD FRONT WILL CROSS THE REGION MONDAY NIGHT INTO TUESDAY. && .NEAR TERM /TONIGHT THROUGH SUNDAY NIGHT/... AS OF 920 PM SATURDAY... THE MAIN UPDATES TO THE FORECAST THIS EVENING WILL BE TO ADDRESS CLOUD COVER AND RAPIDLY FALLING TEMPS. MID CLOUDS UPSTREAM EARLIER THIS EVENING WERE MORE ROBUST AND EVENING PRODUCING SOME VERY LIGHT PRECIP OVER SOUTHWESTERN NC...BUT HAVE SINCE DECREASED IN COVERAGE AS THEY DRIFT SOUTHWEST TO NORTHEAST ACROSS THE AREA. IN AREAS WHERE SKIES HAVE BEEN MOSTLY CLEAR...PARTICULARLY OVER THE EASTERN HALF OF THE CWA...TEMPS HAVE QUICKLY FALLEN INTO THE UPPER 40S AND LOWER 50S. THE LATEST RAP CONTINUES TO INDICATE MOISTURE UPSTREAM INTO THE AREA WITH A PERIOD OF ISENTROPIC LIFT SUFFICIENT FOR SCATTERED SHOWERS...MAINLY AROUND THE WESTERN PIEDMONT. DUE TO THE EXPECTED INCREASE IN MID LEVEL CLOUD COVER...IN THE 4000-6000 FT RANGE BASED ON UPSTREAM OBS AND FORECAST SOUNDINGS...THERE IS STILL SOME UNCERTAINTY REGARDING THE COVERAGE OF FOG/STRATUS. WHERE SKIES ARE CLEAR...VISIBILITIES HAVE FALLEN INTO THE 3 TO 6 MILE RANGE IN SOME SPOTS...BUT NO FURTHER. WILL CONTINUE TO MONITOR THESE TRENDS TO SEE IF A DENSE FOG ADVISORY IS NEED LATER TONIGHT....BUT CURRENT THINKING IS THAT IT MAY BE MORE LIKELY OVER EASTERN AREAS. WITH TEMPS APPROACHING FORECAST MINS IN SOME OUTLYING AREAS...ALSO IN RESPONSE TO THE CLEAR SKIES...WILL LOWER MIN TEMPS A COUPLE DEGREES. HOWEVER...IF CLOUDS MOVE IN AS EXPECTED...TEMPS SHOULD BEGIN TO LEVEL OUT AND REMAIN IN THE UPPER 40S AND LOWER 50S. -BLS AFTER THE MORNING LOW CLOUDS/FOG LIFT AND DISPERSE AND ISOLATED SHOWER ACTIVITY EXITS THE AREA...A MIX OF SUN AND CLOUDS WILL SUPPORT DAYTIME HIGHS IN THE MID TO UPPER 60S NORTH TO LOWER/MID 70S SOUTH. THE UPSTREAM TROUGH WILL BEGIN TO DIG INTO THE SOUTHERN PLAINS SUNDAY NIGHT WITH ATTENDANT SFC COLD FRONT ADVANCING EAST INTO THE TN VALLEY. RISING PWATS FROM STRENGTHENING WARM MOIST AIR ADVECTION...INCREASING RIGHT-ENTRANCE REGION DYNAMICS...THE POTENTIAL FOR WEAK INSTABILITY ALOFT ALONG WITH THE PROSPECTS OF SOME WEAK SHORTWAVE DISTURBANCES TO MOVE THROUGH THE AREA IN THE SWLY FLOW ALOFT WILL SUPPORT ISOLATED SHOWERS...MAINLY IN THE WEST LATE SUNDAY NIGHT. && .SHORT TERM /MONDAY THROUGH TUESDAY/... AS OF 300 AM SUNDAY... THE FAVORED EC MODEL CONTINUES TO SHOW LESS AND LESS IN THE WAY OF SIGNIFICANT RAIN FOR CENTRAL NC WITH THE PASSAGE OF THE COLD FRONT MONDAY NIGHT AND TUESDAY. EVEN TUESDAY IS MOSTLY DRY NOW WITH VERY LITTLE IN THE WAY OF ANY POST-FRONTAL RAIN NOW FORECAST. THESE TRENDS ARE SUPPORTED BY THE OPERATIONAL GFS/NAM. TIMING OF THE FRONT... THE FRONT STILL APPEARS ON TARGET TO REACH INTO THE NW PIEDMONT BY AROUND SUNSET MONDAY NIGHT. OUT AHEAD OF THE FRONT... WARM AND BREEZY CONDITIONS ARE EXPECTED. HIGHS SHOULD THREATEN DAILY RECORDS. SEE THE LIST BELOW IN THE CLIMATE SECTION. THEN... A LINE OF SHOWERS IS EXPECTED TO PRECEDE THE FRONT INTO THE WESTERN PIEDMONT BY SUNSET... THEN DIE OUT AS IT MOVES INTO THE MORE STABLE AIR OUT OVER THE PIEDMONT. WE WILL KEEP LIKELY POP FOR LATE MON AND MON EVENING IN THE WEST... WITH ONLY CHANCE POPS EAST. THERE IS STILL A CHANCE OF SHOWERS INTO EARLY TUESDAY... OR PATCHY LIGHT RAIN... BUT QPF SHOULD BE LESS THAN 0.25 FOR THE EVENT FOR CENTRAL NC. LOCALLY UP TO 0.50 MAY FALL JUST TO OUR WEST IN THE FOOTHILLS. EXPECT SKIES TO BECOME PARTLY SUNNY TUESDAY... BREEZY AND COOLER. HIGHS IN THE 50S. && .LONG TERM /WEDNESDAY THROUGH SATURDAY/... AS OF 300 AM SUNDAY... THE LATEST MODELS ARE COMING MORE IN LINE WITH A SOLUTION THAT KEEPS THE BEST CHANCE OF SIGNIFICANT RAIN ALONG THE COAST WEDNESDAY AND WEDNESDAY NIGHT. EVEN THE LATEST AND FAVORED OPERATIONAL EUROPEAN MODEL KEEPS THE BEST RAIN ALONG THE COAST AND OFFSHORE WHERE THE MAIN WAVES OF LOW PRESSURE FORM ALONG THE BAROCLINIC ZONE. IT IS LOOKING MORE AND MORE LIKE A DRY WEEK FOR CENTRAL NC. WE WILL MAINTAIN A CHANCE OF RAIN IN THE EAST LATE TUESDAY NIGHT AND WEDNESDAY... WITH ONLY A SLIGHT CHANCE INTO THE SE PIEDMONT AND COASTAL PLAIN. OTHERWISE... GENERALLY DRY WEATHER IS EXPECTED TUESDAY... THURSDAY AND FRIDAY WITH COOLER TEMPS BACK TOWARD SEASONAL NORMALS. && .AVIATION /06Z SUNDAY THROUGH THURSDAY/... AS OF 235 AM SUNDAY... 24-HR TAF PERIOD: A FAIR AMOUNT OF UNCERTAINTY PERSISTS WITH REGARD TO HOW LOW CEILINGS AND VISBYS WILL FALL THROUGH 12Z THIS MORNING. INCREASING LOW AND MID-LEVEL CLOUD COVER SHOULD PREVENT VISBYS LOWER THAN MVFR/IFR IN MOST LOCATIONS...EXCEPT PERHAPS AT THE RWI AND FAY TERMINALS. REGARDLESS OF VISBYS...MVFR/IFR CEILINGS WILL BE POSSIBLE AT THE RDU/INT/GSO TERMINALS BETWEEN 06-12Z...PRIMARILY AT INT/GSO WHERE ELEVATED SHOWER ACTIVITY WILL BE POSSIBLE. EXPECT SUB-VFR FOG OR CEILINGS TO LIFT AND IMPROVE BETWEEN 12-15Z...WITH VFR CONDITIONS LIKELY IN MOST AREAS BY 15-18Z...EXCEPT PERHAPS AT THE INT/GSO TERMINALS WHERE MVFR CEILINGS MAY PERSIST INTO THE AFTERNOON. CEILINGS ARE EXPECTED TO DETERIORATE TO LIFR BETWEEN 03-12Z MONDAY AS SOUTHWESTERLY FLOW ADVECTS LOW-LEVEL MOISTURE INTO LOOKING AHEAD: LIFR CEILINGS ARE EXPECTED TO LIFT AND IMPROVE TO MVFR...PERHAPS VFR...BETWEEN 12-18Z MONDAY AS A COLD FRONT APPROACHES THE MOUNTAINS FROM THE WEST AND SOUTHWESTERLY WINDS STRENGTHEN TO 15-20 KT WITH GUSTS UP TO 30 KT. A PERIOD OF MVFR CEILINGS AND SHOWER ACTIVITY WILL BE POSSIBLE AS THE FRONT CROSSES THROUGH THE CAROLINAS MONDAY NIGHT AND TUESDAY MORNING...WITH A POTENTIAL FOR A PROLONGED PERIOD OF MVFR/IFR CEILINGS AT THE FAY/RWI TERMINALS TUESDAY INTO WEDNESDAY AS THE FRONT TEMPORARILY STALLS NEAR OR JUST OFFSHORE THE CAROLINA COAST. -VINCENT && .CLIMATE... DAILY RECORD HIGHS FOR MONDAY (DECEMBER 10): RDU: 81 (2007) GSO: 78 (2007) FAY 79 (2007) && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...VINCENT NEAR TERM...CBL/BLS SHORT TERM...BADGETT LONG TERM....BADGETT AVIATION...VINCENT CLIMATE...BADGETT
AREA FORECAST DISCUSSION
NWS RALEIGH NC
237 AM EST SUN DEC 9 2012 .SYNOPSIS... A WARM MOIST SOUTHERLY FLOW AHEAD OF AN APPROACHING COLD FRONT WILL RESULT IN ABOVE NORMAL TEMPERATURES THROUGH MONDAY. THE COLD FRONT WILL CROSS THE REGION MONDAY NIGHT INTO TUESDAY. && .NEAR TERM /TONIGHT THROUGH SUNDAY NIGHT/... AS OF 920 PM SATURDAY... THE MAIN UPDATES TO THE FORECAST THIS EVENING WILL BE TO ADDRESS CLOUD COVER AND RAPIDLY FALLING TEMPS. MID CLOUDS UPSTREAM EARLIER THIS EVENING WERE MORE ROBUST AND EVENING PRODUCING SOME VERY LIGHT PRECIP OVER SOUTHWESTERN NC...BUT HAVE SINCE DECREASED IN COVERAGE AS THEY DRIFT SOUTHWEST TO NORTHEAST ACROSS THE AREA. IN AREAS WHERE SKIES HAVE BEEN MOSTLY CLEAR...PARTICULARLY OVER THE EASTERN HALF OF THE CWA...TEMPS HAVE QUICKLY FALLEN INTO THE UPPER 40S AND LOWER 50S. THE LATEST RAP CONTINUES TO INDICATE MOISTURE UPSTREAM INTO THE AREA WITH A PERIOD OF ISENTROPIC LIFT SUFFICIENT FOR SCATTERED SHOWERS...MAINLY AROUND THE WESTERN PIEDMONT. DUE TO THE EXPECTED INCREASE IN MID LEVEL CLOUD COVER...IN THE 4000-6000 FT RANGE BASED ON UPSTREAM OBS AND FORECAST SOUNDINGS...THERE IS STILL SOME UNCERTAINTY REGARDING THE COVERAGE OF FOG/STRATUS. WHERE SKIES ARE CLEAR...VISIBILITIES HAVE FALLEN INTO THE 3 TO 6 MILE RANGE IN SOME SPOTS...BUT NO FURTHER. WILL CONTINUE TO MONITOR THESE TRENDS TO SEE IF A DENSE FOG ADVISORY IS NEED LATER TONIGHT....BUT CURRENT THINKING IS THAT IT MAY BE MORE LIKELY OVER EASTERN AREAS. WITH TEMPS APPROACHING FORECAST MINS IN SOME OUTLYING AREAS...ALSO IN RESPONSE TO THE CLEAR SKIES...WILL LOWER MIN TEMPS A COUPLE DEGREES. HOWEVER...IF CLOUDS MOVE IN AS EXPECTED...TEMPS SHOULD BEGIN TO LEVEL OUT AND REMAIN IN THE UPPER 40S AND LOWER 50S. -BLS AFTER THE MORNING LOW CLOUDS/FOG LIFT AND DISPERSE AND ISOLATED SHOWER ACTIVITY EXITS THE AREA...A MIX OF SUN AND CLOUDS WILL SUPPORT DAYTIME HIGHS IN THE MID TO UPPER 60S NORTH TO LOWER/MID 70S SOUTH. THE UPSTREAM TROUGH WILL BEGIN TO DIG INTO THE SOUTHERN PLAINS SUNDAY NIGHT WITH ATTENDANT SFC COLD FRONT ADVANCING EAST INTO THE TN VALLEY. RISING PWATS FROM STRENGTHENING WARM MOIST AIR ADVECTION...INCREASING RIGHT-ENTRANCE REGION DYNAMICS...THE POTENTIAL FOR WEAK INSTABILITY ALOFT ALONG WITH THE PROSPECTS OF SOME WEAK SHORTWAVE DISTURBANCES TO MOVE THROUGH THE AREA IN THE SWLY FLOW ALOFT WILL SUPPORT ISOLATED SHOWERS...MAINLY IN THE WEST LATE SUNDAY NIGHT. && .SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/... AS OF 300 PM SATURDAY... A COLD FRONT WILL APPROACH AND CROSS THE REGION OVERNIGHT MONDAY INTO TUESDAY...ALTHOUGH THERE ARE STILL SOME TIMING DIFFERENCES AMONG THE MODELS...BUT THERE CONTINUES TO SOME TREND OF A SLOWER PASSAGE. AHEAD OF THE FRONT...INCREASING SOUTHWESTERLY WINDS WILL USHER IN MOISTURE AND EVEN MORE WARMTH DURING THE DAY ON MONDAY. TEMPS ARE EXPECTED TO RANGE FROM THE LOW 70S ACROSS THE NORTHWEST TO THE MID 70S FURTHER SOUTH AND EAST. THERE COULD EVEN BE SOME UPPER 70S ACROSS THE SOUTHEAST...ALTHOUGH THE AMOUNT OF CLOUD COVER WILL BE THE DETERMINING FACTOR AND AT THIS TIME...IT LOOKS LIKE THERE WILL BE SUFFICIENT CLOUD COVER TO HOLD TEMPS DOWN SOME. HEATING MAY ALSO BE TEMPERED SOME IN THIS REGION AS DEWPOINTS RISE INTO THE LOWER 60S. PRECIP CHANCES WILL INCREASE DURING THE DAY ON MONDAY AS WARM AIR ADVECTION INCREASES ACROSS THE REGION...WITH SOME SPOTTY SHOWERS POSSIBLE DURING THE DAY. THE BEST CHANCE OF PRECIP WILL COME OVERNIGHT ON MONDAY AND INTO EARLY TUESDAY AS THE FRONT CROSSES THE AREA. AS STATED ABOVE...THERE ARE SOME TIMING DIFFERENCES WITH RESPECT TO THE SPEED OF THE FRONT...BUT WILL CONTINUE TO SHOW PRECIP CHANCES TRENDING DOWNWARD LATE TUESDAY AFTERNOON/EVENING. INSTABILITY APPEARS TO BE MARGINAL (AT BEST) AS THE FRONT CROSSES THE AREA MONDAY NIGHT...BUT CANNOT COMPLETELY RULE OUT AN ISOLATED THUNDERSTORM OR TWO. TEMPS MONDAY NIGHT AND TUESDAY WILL ULTIMATELY BE DETERMINED BY THE TIMING OF THE FRONT AND ASSOCIATED PRECIP AND EVENTUAL CAA. WITH THE SLIGHTLY SLOWER FRONTAL TIMING...WILL SHOW MILD TEMPS MONDAY NIGHT...GENERALLY IN THE 50S. HIGHS ON TUESDAY ARE EXPECTED TO BE IN THE MID/UPPER 50S TO LOW/MID 60S AND MAY VERY WELL OCCUR IN THE MORNING AND THEN FALL THROUGHOUT THE DAY. OVERNIGHT LOWS TUESDAY NIGHT WILL LIKELY BE IN THE MID/UPPER 30S TO NEAR 40 DEGREES. && .LONG TERM /WEDNESDAY THROUGH SATURDAY/... AS OF 300 PM SATURDAY... WEDNESDAY THROUGH THURSDAY...THEN THERE IS QUITE A BIT OF UNCERTAINTY WITH RESPECT TO THE WEATHER FOR THIS TIME FRAME. BOTH THE GFS AND ECMWF SHOW THE FRONT HANGING NEAR THE COAST WITH MULTIPLE LOW PRESSURE WAVES TRACKING ALONG IT AND SPREADING PRECIP INTO EASTERN NC...ALTHOUGH HOW FAR EAST IS IN QUESTION. THE GFS THEN SHOWS A MID LEVEL KICKER WAVE MOVING INTO THE AREA WEDNESDAY WHICH WOULD PUSH THE FRONT AND ASSOCIATED PRECIP OUT TO SEA. THE ECMWF IS ALMOST 12-18 HOURS SLOWER WITH THIS MID LEVEL WAVE...HOWEVER THIS IS SLIGHTLY FASTER THAN PREVIOUS RUNS OF THE ECMWF...SO THIS WILL HAVE TO BE MONITORED. FOR NOW...WILL GO NO MORE THAN SLIGHT CHANCE POPS FOR THIS TIME FRAME UNTIL MODELS COME INTO BETTER AGREEMENT AND WILL JUST KEEP POPS CONFINED TO THE EASTERN PORTIONS OF THE FORECAST AREA. TEMPS WILL LIKELY BE NEAR TO SLIGHTLY ABOVE NORMAL DURING THIS TIME FRAME. FRIDAY THOUGH SATURDAY...CONDITIONS THEN LOOK TO IMPROVE FOR THE END OF THE WORK WEEK AS SURFACE HIGH PRESSURE AND MID LEVEL RIDGING BUILD INTO THE AREA. MODELS THEN SHOW THE NEXT SYSTEM APPROACHING THE REGION OVER THE WEEKEND...WITH CLOUDS AND PRECIP CHANCES POSSIBLY BEGINNING TO INCREASE LATE SATURDAY (ALTHOUGH TIMING THIS FAR OUT IS ALWAYS IN QUESTION). TEMPS WILL SLOWLY MODERATE AT THE END OF THE WEEK AND ESPECIALLY INTO SATURDAY AS THE SURFACE HIGH MOVES OFFSHORE AND SOUTHERLY FLOW RETURNS TO THE AREA. && .AVIATION /06Z SUNDAY THROUGH THURSDAY/... AS OF 235 AM SUNDAY... 24-HR TAF PERIOD: A FAIR AMOUNT OF UNCERTAINTY PERSISTS WITH REGARD TO HOW LOW CEILINGS AND VISBYS WILL FALL THROUGH 12Z THIS MORNING. INCREASING LOW AND MID-LEVEL CLOUD COVER SHOULD PREVENT VISBYS LOWER THAN MVFR/IFR IN MOST LOCATIONS...EXCEPT PERHAPS AT THE RWI AND FAY TERMINALS. REGARDLESS OF VISBYS...MVFR/IFR CEILINGS WILL BE POSSIBLE AT THE RDU/INT/GSO TERMINALS BETWEEN 06-12Z...PRIMARILY AT INT/GSO WHERE ELEVATED SHOWER ACTIVITY WILL BE POSSIBLE. EXPECT SUB-VFR FOG OR CEILINGS TO LIFT AND IMPROVE BETWEEN 12-15Z...WITH VFR CONDITIONS LIKELY IN MOST AREAS BY 15-18Z...EXCEPT PERHAPS AT THE INT/GSO TERMINALS WHERE MVFR CEILINGS MAY PERSIST INTO THE AFTERNOON. CEILINGS ARE EXPECTED TO DETERIORATE TO LIFR BETWEEN 03-12Z MONDAY AS SOUTHWESTERLY FLOW ADVECTS LOW-LEVEL MOISTURE INTO LOOKING AHEAD: LIFR CEILINGS ARE EXPECTED TO LIFT AND IMPROVE TO MVFR...PERHAPS VFR...BETWEEN 12-18Z MONDAY AS A COLD FRONT APPROACHES THE MOUNTAINS FROM THE WEST AND SOUTHWESTERLY WINDS STRENGTHEN TO 15-20 KT WITH GUSTS UP TO 30 KT. A PERIOD OF MVFR CEILINGS AND SHOWER ACTIVITY WILL BE POSSIBLE AS THE FRONT CROSSES THROUGH THE CAROLINAS MONDAY NIGHT AND TUESDAY MORNING...WITH A POTENTIAL FOR A PROLONGED PERIOD OF MVFR/IFR CEILINGS AT THE FAY/RWI TERMINALS TUESDAY INTO WEDNESDAY AS THE FRONT TEMPORARILY STALLS NEAR OR JUST OFFSHORE THE CAROLINA COAST. -VINCENT && .CLIMATE... DAILY RECORD HIGHS FOR MONDAY (DECEMBER 10): RDU: 81 (2007) GSO: 78 (2007) FAY 79 (2007) && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...VINCENT NEAR TERM...CBL/BLS SHORT TERM...KRR LONG TERM....KRR AVIATION...VINCENT CLIMATE...RAH
AREA FORECAST DISCUSSION
NWS WILMINGTON OH
1253 AM EST SUN DEC 9 2012 .SYNOPSIS... HIGH PRESSURE WILL BUILD OVER THE GREAT LAKES IN THE WAKE OF A DEPARTING COLD FRONT TONIGHT. THIS WILL GIVE A BRIEF RESPITE TO THE RAINFALL UNTIL A WARM FRONT DEVELOPS OVER KENTUCKY EARLY SUNDAY AND THEN LIFTS NORTHWARD. LOW PRESSURE WILL THEN TRACK NORTHEAST THROUGH THE OHIO VALLEY AND ANOTHER COLD FRONT OVER THE AREA WILL BE THE FOCUS FOR MORE RAINFALL SUNDAY NIGHT AND MONDAY. && .NEAR TERM /UNTIL 6 AM THIS MORNING/... SHOWERS AND A FEW THUNDERSTORMS HAVE BEEN DEVELOPING ACROSS KENTUCKY OVER THE PAST FEW HOURS WITH A WARM FRONT OVER THE AREA. EXPECT THE SHOWERS TO REMAIN MAINLY ALONG AND SOUTH OF THE OHIO RIVER INTO THE EARLY MORNING HOURS PER THE LATEST HRRR AND RAP13 RUNS...BUT THE RAIN WILL LIKELY BEGIN TO SPREAD FURTHER NORTH TOWARDS DAYBREAK. BUMPED UP POPS A BIT TO ACCOUNT FOR THIS. REST OF FORECAST LARGELY REMAINS ON TRACK WITH ONLY A FEW MINOR TWEAKS. && .SHORT TERM /6 AM THIS MORNING THROUGH MONDAY NIGHT/... WARM FRONT OVER KENTUCKY LIFTS NORTH THROUGH OHIO DURING THE DAY SUNDAY AND A SURFACE LOW TRACKS EAST ALONG IT AS IT DOES. THE COMBINATION OF THE TWO WILL MEAN ANOTHER MILD DAY WITH AN EVER- INCREASING CHANCE FOR SHOWERS. ONCE THE LOW REACHES LAKE ERIE SUNDAY NIGHT...A COLD FRONT ORIENTED ALONG THE I-71 CORRIDOR WILL BE A FOCUS FOR SHOWERS AND EVEN SOME THUNDERSTORMS. RAIN AT TIMES COULD BE MODERATE IN INTENSITY AND RIVERS AND STREAMS THAT MAY BE RUNNING HIGH WILL NEED TO BE MONITORED A LITTLE CLOSER AS THE NEXT ROUND OF RAIN COMES IN. THE MODERATE RAINFALL WILL PROBABLY OCCUR IN THE LATER EVENING AS THE FLOW AT THE SURFACE AND ALOFT IS NEAR PARALLEL SOUTHWEST TO NORTHEAST. THIS WILL TAP THE AVAILABLE GULF MOISTURE WITH A STRONG TRANSPORT WIND OVER THE REGION UNTIL THE SURFACE GRADUALLY SHOWS AND EASTWARD PROGRESSION ON MONDAY IN RESPONSE TO THE COLDER AIR BEING USHERED IN ON NORTHWEST WINDS. A LARGE PORTION OF THE ATMOSPHERE WILL SEE QUITE A BIT OF SLANTWISE CONVECTION AND THE THREAT FOR THUNDER IN THESE SHOWERS IS HIGHER THAN AVERAGE...THOUGH THE SEVERE THREAT INHERENT WITH THUNDERSTORMS WILL BE QUITE MINIMAL IF IT DOES EXIST AT ALL. I TOOK NAM CAPE VALUES OVER 30 TO INDICATE THE THREAT FOR THUNDER. WITH REGARDS TO THE HEAVIER RAIN...THIS STARTED SUNDAY EVENING AND RAN THROUGH MONDAY EVENING WHERE POPS LIKELY OR HIGHER WERE BEING FORECAST. THE RAIN WILL TURN OFF NORTHWEST TO SOUTHEAST ON MONDAY WITH VERY LITTLE ACTIVITY SLATED TO REMAIN MONDAY NIGHT. THE DEEPER COLD AIR IS WELL BEHIND THE RAINFALL SO I HAVE REMOVED MENTION OF ANY SNOW. TEMPERATURES WERE ONLY MINORLY ADJUSTED AND ARE SHOWING A PRETTY GOOD CONSISTENCY BETWEEN GUIDANCE VALUES AND THE PREVIOUS FORECAST. && .LONG TERM /TUESDAY THROUGH SATURDAY/... AS THE PERIOD BEGINS...THE MODELS ARE SHOWING SFC HIGH PRESSURE BEGINNING TO PUSH INTO THE REGION. THE HIGH STRENGTHENS IT GRIP OVER THE REGION DURING THE DAY TUESDAY. THE CENTER OF THE HIGH WILL STRETCH OVER THE UPPER OHIO VALLEY BY DAYBREAK ON WEDNESDAY AND HIGH PRESSURE WILL CONTROL THE REGIONS WEATHER INTO FRIDAY. RIGHT NOW MODELS ARE IN GOOD AGREEMENT IN FORMING A SFC LOW IN THE PLAINS ON FRIDAY AND EJECTING IT OUT INTO THE WESTERN LAKES BY SATURDAY. FA WILL ONCE AGAIN BE ON THE WARM SIDE OF THE SYSTEM...SO IT LOOKS LIKE A ANOTHER SHOT OF RAIN FOR NEXT SATURDAY. TUESDAY SHOULD BE THE COLDEST DAY OF THE WEEK WITH CAA BEHIND THE DEPARTING SYSTEM. HIGH WILL ONLY BE IN THE MID 30S TO AROUND 40. MOSTLY CLEAR SKIES TUESDAY WITH THE BUILDING HIGH SHOULD ALLOW TEMPERATURES TO FALL BACK INTO THE LOWER TO MID 20S. A GRADUAL WARM UP THEN BEGINS ON WEDNESDAY AS HIGH ARE EXPECTED TO PUSH INTO THE LOWER TO MID 40S. HIGHS WILL PUSH INTO THE UPPER 40S TO LOWER 50S BY THE END OF THE WEEK. ANOTHER COOL NIGHT IS EXPECTED WEDNESDAY NIGHT WITH TEMPERATURES FALLING BACK INTO THE 20S BEFORE THE WARMER AIR BEGINS TO WORK IN AHEAD OF THE DEVELOPING SYSTEM BY THE END OF THE PERIOD. && .AVIATION /06Z SUNDAY THROUGH THURSDAY/... REMAINING MVFR CIGS WILL GRADUALLY LOWER TO IFR THIS MORNING AS A WARM FRONT TO OUR SOUTH BEGINS TO LIFT NORTHWARD ACROSS THE AREA. SHOWERS ALONG THIS FRONT SHOULD REMAIN CONFINED TO THE SOUTHERN TERMINALS THIS MORNING. AREAS OF MVFR MIST WILL BE LIKELY ACROSS THE KDAY/KILN THROUGHOUT TONIGHT. AS THE WARM FRONT LIFTS NORTH OF THE TERMINALS DURING THE LATE MORNING...CIGS SHOULD RAISE BACK TO MVFR. THE WARM FRONT MAY NOT MAKE IT AS FAR AS KDAY...SO KEPT IFR CIGS IN THEIR FORECAST THROUGHOUT THE DAY. BY LATE THIS AFTERNOON...SHOWERS AND POSSIBLY IFR CIGS WILL SPREAD ACROSS ALL TERMINALS AHEAD OF A DEVELOPING LOW PRESSURE SYSTEM. THERE MAY BE ENOUGH INSTABILITY ACROSS THE SOUTHERN TERMINALS LATE THIS AFTERNOON TO PRODUCE SOME THUNDER AS WELL. PRECIPITATION IS EXPECTED TO AFFECT ALL TERMINALS THEREAFTER THROUGH THE END OF THE TAF PERIOD. OUTLOOK...IFR CEILINGS AND MVFR VISIBILITIES LIKELY LATE SUNDAY NIGHT WITH IMPROVEMENT TO MVFR CEILINGS ON MONDAY. MVFR CEILINGS MAY LINGER INTO MONDAY NIGHT AND TUESDAY MORNING. && .ILN WATCHES/WARNINGS/ADVISORIES... OH...NONE. KY...NONE. IN...NONE. && $$ SYNOPSIS...FRANKS NEAR TERM...KURZ SHORT TERM...FRANKS LONG TERM...SITES AVIATION...LATTO
AREA FORECAST DISCUSSION
NWS BLACKSBURG VA
455 AM EST SUN DEC 9 2012 .SYNOPSIS... A COLD FRONT FROM NEW ENGLAND TO THE TENNESSEE VALLEY WILL MOVE SLOWLY SOUTHEAST TODAY BEFORE STALLING AND PUSHING BACK NORTH AS WARM FRONT TONIGHT. A MUCH STRONGER COLD FRONT WILL CROSS THROUGH THE AREA FROM THE WEST MONDAY EVENING. COOL HIGH PRESSURE WILL BUILD IN BEHIND THE FRONT FOR TUESDAY INTO FRIDAY. && .NEAR TERM /THROUGH TONIGHT/... AS OF 430 AM EST SATURDAY... SCATTERED TO NUMEROUS SHOWERS...ASSOCIATED WITH A SHORT WAVE MOVING THROUGH WEST VIRGINIA...WERE TRACKING NORTHEAST ACROSS THE WESTERN COUNTY WARNING AREA EARLY THIS MORNING. WATER VAPOR LOOP SHOWED ANOTHER SHORT WAVE JUST ENTERING WESTERN KENTUCKY AND TENNESSEE WHICH MODELS TAKE ALONG THE SAME TRACK. THIS SHOULD BRING MORE SHOWERS TO THE WESTERN COUNTY WARNING AREA THIS AFTERNOON. SCATTERED SHOWERS WERE ALSO MOVING THROUGH SOUTHSIDE VIRGINIA. ONCE THESE SHOWERS MOVE THROUGH THIS MORNING THE CHANCE OF PRECIPITATION WILL BE LOWER IN THIS PART OF THE FORECAST AREA FOR THE REST OF THE DAY. THE COLD FRONT EXTENDED FRONT NEW JERSEY TO CENTRAL KENTUCKY. ONCE THE WEST VIRGINIA SHORT WAVE MOVES SLIGHTLY FARTHER NORTH...THE FRONT WILL ADVANCE SOUTH INTO THE FOOTHILLS THIS MORNING. LOCAL WRK AND LATEST RAP SHOWED THE WEDGE REACHING THE ROANOKE RIVER BY THE END OF THE DAY BEFORE ADVANCING SLOWLY BACK NORTH TONIGHT. HAVE MORE CLOUD COVER AND COOLER TEMPERATURES NORTH OF THE FRONT TODAY AND MORE FOG OVERNIGHT TONIGHT. USED A NON DIURNAL TREND FOR HOURLY TEMPERATURES OVERNIGHT. THOSE LOCATIONS THAT PULL OUT OF THE WEDGE WILL LIKELY WARM UP AS THEY GET BACK INTO THE WARM SECTOR. && .SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/... AS OF 330 AM EST SUNDAY... PRIMARY FOCUS FOR THE SHORT TERM FORECAST WAS ON THE TIMING OF THE COLD FRONT MOVING THROUGH THE FORECAST AREA LATE MONDAY AND MONDAY NIGHT. WITH SFC WAVES RIDING UP THE SFC BOUNDARY AND INITIAL UPPER LEVEL SHORTWAVE LIFTING NORTH WITH MORE ENERGY DIGGING INTO THE BASE OF THE UPPER LEVEL TROF IN THE CENTRAL U.S....CONTINUED TO LEAN TOWARD THE SLOWER MODEL SOLUTIONS. FOR THIS FORECAST PACKAGE...THE SLOWER NAM AND SREF WERE PREFERRED. AS WINDS VEER IN RESPONSE TO THE APPROACH OF THE UPPER LEVEL TROF...SFC WEDGE SHOULD HAVE ERODED BY 12Z MONDAY...OR SHORTLY THEREAFTER...LEAVING THE ENTIRE FORECAST FIRMLY ENTRENCHED IN THE WARM SECTOR. A DEEP SOUTHWEST FLOW ALONG WITH SOME BREAKS IN THE CLOUDS IN THE EAST SHOULD ALLOW TEMPS TO SOAR WELL ABOVE NORMAL...BUT STILL BELOW RECORDS FOR 12/10. BEST 850-300MB OMEGA PER THE NAM ARRIVES IN THE WEST AROUND 18Z MONDAY...BUT LIFTS TO THE NORTH AFTERWARDS WITH UPPER LEVEL SHORTWAVE. THIS LEAVES UNCERTAINTY ON HOW FAR EAST PRECIPITATION SHIELD CAN TRAVEL. AS A RESULT...KEPT MUCH HIGHER POPS IN THE MOUNTAINS...WITH HIGH CHANCE POPS IN THE EAST LATE MONDAY AND MONDAY NIGHT. NAM FORECAST SOUNDINGS INDICATE THE LOWER LEVEL OF THE ATMOSPHERE BEGINS DRYING WHEN TEMPS COLD ENOUGH FOR SNOW BEGINS TO ARRIVE ALONG THE WESTERN SLOPES. MAY STILL BE ABLE TO SQUEEZE OUT SOME LIGHT SNOW SHOWERS IN THE HIGHEST ELEVATIONS OF SOUTHEAST WV/ALLEGHANY HIGHS FOR A FEW HOURS TUESDAY MORNING. EVEN THE SLOWEST SREF KEEPS SFC BOUNDARY WELL SOUTHEAST OF THE FORECAST AREA ON TUESDAY. WEAK SFC WAVES MOVING THROUGH EASTERN NC/VA ON TUESDAY WILL KEEP SOME CLOUDS IN THE FAR EAST...BUT LOW LEVEL NORTHWEST WINDS WILL KEEP THE FORECAST AREA DRY BY 18Z. AS SFC RIDGE QUICKLY BUILDS OVER THE AREA TUESDAY...COLD AIR ADVECTION DIMINISHES DURING THE DAY AND EXPECT TEMPS TO RECOVER AND USED A BLEND OF THE NAM/GFS MOS GUIDANCE FOR HIGHS. && .LONG TERM /WEDNESDAY THROUGH SATURDAY/... AS OF 330 PM EST SATURDAY... HIGH PRESSURE WILL CONTROL THE WEATHER PATTERN THROUGH FRIDAY. WILL BE KEEPING AN EYE ON A LOW PRESSURE SYSTEM DEVELOPING ALONG THE CAROLINA COAST OF WEDNESDAY/THURSDAY TO SEE IF ANY SHOWER ACTIVITY ADVANCES INTO THE PIEDMONTS...BUT BECOMING MORE CONFIDENT THAT THIS ACTIVITY WILL STAY EAST OF THE AREA. THE NEXT BIG STORM SYSTEM TO WATCH WILL ARRIVE NEXT WEEKEND AS A DEEP LOW PRESSURE SYSTEM PASSES EASTWARD FROM THE CENTRAL PLAINS INTO THE GREAT LAKES...DRAGGING A COLD FRONT TOWARD OUR AREA. && .AVIATION /10Z SUNDAY THROUGH THURSDAY/... AS OF 1115 PM EST SATURDAY... BROKEN BAND OF SHOWERS WILL CONTINUE TO AFFECT KLWB AND PERHAPS KBLF OVERNIGHT WITH A SLOW DOWNTURN TO MVFR THERE WITH MAINLY VFR PREVAILING ELSW BEFORE FOG DEVELOPS SHORTLY AFTER MIDNIGHT. MOISTURE WILL THEN DEEPEN TOWARD DAWN SUNDAY AS A COLD FRONT TO THE NW BACKDOORS SOUTH DOWN EAST OF THE MOUNTAINS BY MORNING. THIS SHOULD AID LIFT SOME ESPCLY AFTER MIDNIGHT WITH CIGS LOWERING TO MVFR MOST SPOTS THEN DROPPING TO IFR OR WORSE IN STRATUS/FOG ESPCLY KROA AND POINTS EAST DURING THE EARLY MORNING HOURS OF SUNDAY. HOWEVER IF SKIES STAY CLEAR LONGER OVERNIGHT THEN COULD ALSO SEE POOR FLYING CONDITIONS DEVELOP SOONER DUE TO FOG AND STRATUS FORMATION. OTRW EARLIER CLOUD COVER MAY LIMIT LOWER CIGS ACROSS THE SE WVA SITES EXCEPT AT KLWB WHERE RAINFALL SHOULD AID FOG FORMATION AND POSSIBLY A PERIOD OF IFR BY DAYBREAK. THE IFR TO MVFR CEILINGS...IN CONJUNCTION WITH THE WEDGE OUT EAST WILL LIKELY BE SLOW TO EXIT SUNDAY MORNING ESPCLY IF DRIZZLE DEVELOPS AND HELPS HOLD LOWER CIGS IN LONGER. ALSO POTENTIAL FOR LIFT TO RESULT IN CONTINUED SCATTERED SHRA ACROSS THE WEST INTO SUNDAY AFTERNOON SO LEFT IN MENTION FROM KBCB WESTWARD. CONDITIONS MAY IMPROVE SLIGHTLY BY SUNDAY AFTERNOON TO MVFR OR EVEN VFR ESPCLY WEST OF THE BLUE RIDGE WITH ONLY A GRADUAL LIFTING OF CIGS/VSBYS FROM SOUTH TO NORTH EAST OF THE BLUE RIDGE. MAY EVEN SEE KLYH/KROA STAY MVFR OR WORSE AT TIMES UNTIL LATE SUNDAY. AGAIN EXPECT MORE FOG AND LOW CLOUDS TO REDEVELOP ESPCLY EAST SUNDAY NIGHT BEFORE THINGS PERHAPS SCOUR OUT TO HIGH END MVFR OR VFR MONDAY MORNING. THEN A STRONGER COLD FRONT PUSHES THROUGH FROM WEST MONDAY NIGHT...BRINGING MVFR TO IFR CONDITIONS ONCE AGAIN WITH POSSIBLY HEAVIER SHOWERS. NORTHWEST CROSS BARRIER WINDS BEHIND THE COLD FRONT WILL LIKELY RESULT IN STRONG MECHANICAL TURBULENCE FOR MONDAY NIGHT AND TUESDAY. CONDITIONS WILL IMPROVE ON TUESDAY EVENING AS HIGH PRESSURE BEGINS TO SETTLE ACROSS THE AREA. LINGERING MOISTURE IN THE MOUNTAINS TUESDAY WILL RESULT IN MVFR CONDITIONS AND THE POSSIBILITY OF SNOW SHOWERS AS COLDER AIR SURGES INTO THE AREA. VFR SHOULD MAKE A GRADUAL RETURN BY TUESDAY NIGHT INTO WEDNESDAY AND THEN LINGER THRU LATE NEXT WEEK. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...NONE. NC...NONE. WV...NONE. && $$ SYNOPSIS...AMS NEAR TERM...AMS SHORT TERM...PH LONG TERM...NF AVIATION...AMS/JH/SK
AREA FORECAST DISCUSSION
NWS WICHITA KS
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
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
1044 AM EST SUN DEC 9 2012 .SYNOPSIS... A SURFACE LOW WILL PUSH NORTHEAST INTO THE OHIO VALLEY TODAY AND LIFT A WARM FRONT IN THE REGION. THIS WILL ALLOW FOR SHOWERS TO RETURN TO THE AREA AND CONTINUE INTO MONDAY. A COLD FRONT WILL CROSS THE AREA ON MONDAY...ALLOWING FOR A CHANGE OVER TO SNOW SHOWERS MONDAY NIGHT WITH A MUCH COOLER AIR MASS BUILDING INTO THE AREA FOR THE MID-WEEK. && .NEAR TERM /THROUGH TONIGHT/... 15Z ENHANCED SHORT TERM FORECAST UPDATE HAS BEEN ISSUED TO ADJUST POPS TODAY TO ACCOUNT FOR THE NEXT WAVE OF SHOWERS. IN ADDITION...THUNDER MENTION HAS BEEN ADDED FOR THIS AFTERNOON INTO EARLY TONIGHT FOR LOCATIONS SOUTH AND WEST OF PITTSBURGH. THE LATEST RAP MID-LEVEL ANALYSIS INDICATES A SHORT WAVE TROUGH MOVING FROM THE NORTHERN PLAINS INTO THE UPPER MIDWEST WITH THE UPPER OHIO VALLEY IN A SOUTHWESTERLY FLOW WELL AHEAD OF THIS FEATURE. AT THE SURFACE...THERE ARE TWO LOWS WELL UPSTREAM...ONE MOVING INTO THE UPPER MIDWEST AND ANOTHER INTO THE MISSOURI VALLEY. THE FRONTAL BOUNDARY BETWEEN THESE TWO LOWS IS THE DEMARCATION BETWEEN A WARM AND MOIST AIR MASS AHEAD AND ARCTIC AIR BUILDING IN BEHIND IT. A WARM FRONT EXTENDS NORTHEASTWARD FROM THE SOUTHERN LOW ACROSS KENTUCKY AND INTO SOUTHERN WV. LOCALLY...THE FIRST SHORT WAVE IS SHIFTING EAST OF THE RIDGES WHILE THE NEXT WAVE IS RIDING ALONG AND NORTH OF THE WARM FRONT AND DEVELOPING ACROSS EASTERN KENTUCKY. THIS AFTERNOON...THE SURFACE LOW ACROSS THE MISSOURI VALLEY WILL QUICKLY LIFT INTO THE OHIO VALLEY...MERGING WITH THE LOW IN THE UPPER MIDWEST AND PULLING THE WARM FRONT NORTHWARD INTO THE UPPER OHIO VALLEY. THE AREA OF SHOWERS AND EMBEDDED ISOLATED THUNDERSTORMS ASSOCIATED WITH THE SHORT WAVE IN KENTUCKY WILL SLIDE NORTHEASTWARD WITH THE WARM FRONT INTO THE UPPER OHIO VALLEY EARLY THIS AFTERNOON. MESOSCALE MODELS ARE SUPPORTIVE OF THIS FEATURE MOVING THROUGH PART OF THE AREA BY LATE EVENING...AND THUS POPS INCREASE TO CATEGORICAL BY 00Z. RAP/NAM MODEL SOUNDINGS AT KZZV INDICATE SOME NARROW CAPE DEVELOPING (LESS THAN 200 J/KG) AFTER 21Z. WITH THE WARM FRONT LIFTING INTO THE AREA AND TDS SURGING INTO THE LOWER TO MID 50S...HAVE ADDED THE SCHC OF THUNDER THIS AFTERNOON INTO THE EVENING FOR LOCATIONS SOUTH AND WEST OF PITTSBURGH. TEMPS TODAY WILL SUBJECT TO THE NORTHWARD PROGRESSION OF THE WARM FRONT. LAMP/WRF-NMM SUGGEST TEMPS WILL BE SLOW TO WARM MUCH OF THE DAY WITH THE WARM SURGE OCCURRING AND HIGH TEMPS OCCURRING AFTER 21Z. THUS...WITH THE FRONT PUSHING INTO THE AREA...QUITE A THERMAL GRADIENT CAN BE EXPECTED FOR HIGHS TODAY THAT WILL RANGE FROM THE LOWER 40S IN JEFFERSON/FOREST COUNTIES TO THE LOWER 60S IN PORTIONS OF NORTH-CENTRAL WV AND EASTERN OHIO. TONIGHT...THE MERGED SURFACE LOW WILL CROSS THE OHIO VALLEY AND PUSH INTO THE EASTERN GREAT LAKES. THE WARM FRONT WILL SHIFT NORTHEAST OF THE AREA AND A COLD FRONT AND ITS ASSOCIATED SURFACE TROUGH WILL BEGIN TO APPROACH FROM THE WEST. BETWEEN WARM FRONTAL SHOWERS AND SCHC THUNDER INITIALLY AND SHOWERS AHEAD OF THE COLD FRONT MOVING IN FROM THE WEST...CATEGORICAL POPS ARE FORECAST THROUGH MUCH OF THE OVERNIGHT. TEMPS WILL DROP OFF LITTLE OVERNIGHT IN WAA...WITH LOWS RANGING FROM THE MID 50S IN NORTH-CENTRAL WV TO THE MID 40S ALONG THE I-80 CORRIDOR. && .SHORT TERM /MONDAY THROUGH WEDNESDAY/... THE SURFACE TROUGH AND COLD FRONT WILL CROSS THE AREA THROUGH THE EARLY PART OF THE DAY...WITH CATEGORICAL POPS. TEMPERATURES WILL REMAIN MILD WITH VALUES MAINLY IN THE UPPER 40S TO MID 50S INTO MIDDAY MONDAY. STRONG CAA WILL THEN BEGIN BEHIND THE FRONT...AS THE AFOREMENTIONED ARCTIC AIR MASS BEGINS TO PUSH IN FROM THE WEST. BEFORE RAIN COMES TO AN END OR CHANGES TO SNOW...CONCUR WITH HPC THAT RAINFALL AMOUNTS FOR SUNDAY INTO MONDAY WILL BE ON THE ORDER OF 1.0 TO 1.3 INCHES. CONSEQUENTLY REMAINING POSTFRONTAL SHOWERS MONDAY NIGHT WILL TURN TO SNOW SHOWERS LATE. THE POSTFRONTAL COLD POOL WILL REMAIN ACROSS THE UPPER OHIO VALLEY INTO WEDNESDAY...KEEPING SKIES MAINLY CLOUDY. HOWEVER CONDITIONS TUESDAY INTO WEDNESDAY SHOULD BE DRY AS INCOMING HIGH PRESSURE SUBSIDENCE AND LOW LEVEL WESTERLY WINDS WILL MITIGATE CHANCES OF LAKE EFFECT SNOW SHOWER DEVELOPMENT. && .LONG TERM /WEDNESDAY NIGHT THROUGH SATURDAY/... GFS ECMWF AND CANADIAN MODEL OUTPUT CONCUR THAT NEARBY HIGH PRESSURE WILL PROMOTE DRY CONDITIONS WEDNESDAY NIGHT INTO FRIDAY. ECMWF AND GFS AGREE THAT A CLOSED MID-LEVEL LOW WILL DEVELOP ACROSS THE CENTRAL PLAINS ON FRIDAY NIGHT AND SHIFT INTO THE GREAT LAKES REGION BY SATURDAY. AHEAD OF THIS FEATURE...CHANCE POPS RETURN TO THE AREA. MODEL PREDICTABILITY A WEEK OUT MAKES IT DIFFICULT TO PIN DOWN SPECIFICS IN FRONTAL PLACEMENT...HOWEVER THIS PATTERN FAVORS THE POTENTIAL FOR OVERRUNNING ALONG WITH WARM FRONTAL RAIN SHOWERS WELL AHEAD OF THE LOW. TEMPERATURES WILL REBOUND TO WARMER THAN NORMAL THIS PERIOD WITH VALUES FRIDAY AND SATURDAY ANYWHERE FROM 5 TO 10 DEGREES ABOVE NORMAL. && .AVIATION /15Z SUNDAY THROUGH THURSDAY/... LOWER CLOUDS HAVE DEPARTED ACROSS THE NORTHERN TERMINALS AT LEAST FOR A TIME WITH VFR MID DECKS AT KFKL AND KDUJ. ELSEWHERE IFR AT TIMES CONTINUES AT KMGW WHILE LOW MVFR REMAINS ELSEWHERE. WARM FRONT EXPECTED TO PUSH NORTH LATER THIS AFTERNOON AND SHOULD BRING CIGS DOWN AS THE AFTERNOON PROGRESSES WITH RAIN DEVELOPING AT ALL SITES. CIGS WILL LOWER TO IFR AFTER A FEW HOURS OF RAIN THIS EVENING. WINDS WILL BE GENERALLY FROM THE EAST NEAR 10 KTS. UNTIL FRONT PUSHES NORTH LATER TONIGHT WHEN SOUTH WINDS AT SIMILAR SPEEDS EXPECTED. .OUTLOOK.../MONDAY THROUGH THURSDAY/... MVFR AND PSBL IFR RESTRICTIONS WL CONTINUE WITH RAIN MONDAY AS A COLD FRONT MOVES THROUGH. MVFR CONDITIONS ARE EXPECTED MONDAY NIGHT INTO TUESDAY. LINGERING RAIN SHOWERS MAY CHANGE TO SCATTERED SNOW SHOWERS BEFORE ENDING EARLY TUESDAY. HIGH PRES AND VFR CONDS ARE EXPECTED LATER TUESDAY THROUGH THURSDAY. && .PBZ WATCHES/WARNINGS/ADVISORIES... MD...NONE. OH...NONE. PA...NONE. WV...NONE. && $$ SYNOPSIS...WOODRUM NEAR TERM...WOODRUM AVIATION...RSMITH
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
611 AM EST SUN DEC 9 2012 .SYNOPSIS... LOW PRESSURE COMING NORTHEAST FROM MISSOURI WILL BRING THE UPPER OHIO VALLEY MILD TEMPERATURES AND BOUTS OF RAIN INTO MONDAY... FOLLOWED BY A COOL DOWN TO SEASONABLE TEMPERATURES TUESDAY. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... BASED OF BLEND OF RECENT SREF MODEL OUTPUT...WITH DETAILS FROM RECENT RAP WRF-NMM AND NAM MODEL RUNS...SHOW A LOW PRESSURE SYSTEM WILL BE MOVING FROM MISSOURI THIS MORNING TO OHIO THIS EVENING. WARM FRONT CONVERGENCE ENHANCED BY JETSTREAM DYNAMICS ALOFT WILL SPAWN A SURGE OF RAIN TO SPREAD NORTHWARD ACROSS THE UPPER OHIO TODAY. LOCATIONS SOUTH OF THE I-70 CORRIDOR CAN EXPECT BOUTS OF RAIN STARTING THIS MORNING...WHILE LOCATIONS FARTHER NORTH MAY NOT GET MUCH RAIN UNTIL AFTERNOON. HAVE ADDED MENTION OF DENSE FOG ACROSS THE HIGHER ELEVATIONS OF TUCKER COUNTY WV AND GARRETT COUNTY MD...BASED ON RECENT SURFACE DATA. FOG SHOULD CONTINUE INTO MID MORNING WHEN FIRST BOUT OF RAIN LESSENS. TEMPERATURES WILL CONTINUE TO BE MILD WITH HIGHS THIS AFTERNOON ABOUT 15 DEGREES WARMER THAN NORMAL...PER BLEND OF GFS AND NAM MOS AND RAP AND GFS LAMP HOURLY VALUES. && .SHORT TERM /6 PM THIS EVENING THROUGH WEDNESDAY/... RECENT SREF MODEL OUTPUT SHOWS A NORTHEAST SURGE OF MODERATE RAIN ACROSS THE UPPER OHIO TONIGHT AND MONDAY...UNTIL THE LOW PRESSURE CENTER PASSES NORTHEAST TO NEW YORK STATE MONDAY AFTERNOON. CONCUR WITH HPC THAT RAIN AMOUNTS FOR THIS EVENT CAN BE ON THE ORDER OF 1.0 TO 1.3 INCHES. TEMPERATURES WILL REMAIN MILD WITH VALUES MAINLY IN THE UPPER 40S TO MID 50S INTO MIDDAY MONDAY. ONCE THE LOW PRESSURE CENTER EXITS NORTHEAST...A COLD FRONTAL PASSAGE WILL ENSUE MONDAY AFTERNOON. THE COOL DOWN CAN BEGIN MONDAY AFTERNOON WITH VALUES LATE MONDAY NIGHT INTO WEDNESDAY NEAR OR SLIGHTLY COLDER THAN NORMAL. CONSEQUENTLY REMAINING POSTFRONTAL SHOWERS MONDAY NIGHT CAN TURN TO SNOW SHOWERS LATE. THE POSTFRONTAL COLD POOL CAN REMAIN ACROSS THE UPPER OHIO VALLEY INTO WEDNESDAY...KEEPING SKIES MAINLY CLOUDY. HOWEVER CONDITIONS TUESDAY INTO WEDNESDAY SHOULD BE DRY AS INCOMING HIGH PRESSURE SUBSIDENCE AND LOW LEVEL WESTERLY WINDS WILL MITIGATE CHANCES OF LAKE EFFECT SNOW SHOWER DEVELOPMENT. && .LONG TERM /WEDNESDAY NIGHT THROUGH SATURDAY/... GFS ECMWF AND CANADIAN MODEL OUTPUT CONCUR THAT NEARBY HIGH PRESSURE WILL PROMOTE DRY CONDITIONS WEDNESDAY NIGHT INTO FRIDAY. ECMWF AND GFS AGREE THAT A CLOSED MID-LEVEL LOW WILL DEVELOP ACROSS THE CENTRAL PLAINS ON FRIDAY NIGHT AND SHIFT INTO THE GREAT LAKES REGION BY SATURDAY. AHEAD OF THIS FEATURE...CHANCE POPS RETURN TO THE AREA. MODEL PREDICTABILITY A WEEK OUT MAKES IT DIFFICULT TO PIN DOWN SPECIFICS IN FRONTAL PLACEMENT...HOWEVER THIS PATTERN FAVORS THE POTENTIAL FOR OVERRUNNING ALONG WITH WARM FRONTAL RAIN SHOWERS WELL AHEAD OF THE LOW. TEMPERATURES WILL REBOUND TO WARMER THAN NORMAL THIS PERIOD WITH VALUES FRIDAY AND SATURDAY ANYWHERE FROM 5 TO 10 DEGREES ABOVE NORMAL. && .AVIATION /11Z SUNDAY THROUGH THURSDAY/... CONDITIONS SHOULD REMAIN MVFR THROUGH THE MORNING AND MUCH OF THE AFTERNOON. THE EXCEPTIONS TO THIS WILL BE FKL/DUJ...WHERE LOW CLOUDS HAVE SCATTERED OUT RESULTING IN VFR CONDITIONS...AND MGW...WHERE MORNING SHOWERS ARE EXPECTED TO CAUSE IFR CEILINGS. WITH WARM FRONT EXPECTED TO ARRIVE A BIT LATER IN THE DAY...HAVE DELAYED MENTION OF RAIN AT ALL SITES EXCEPT MGW UNTIL THE AFTERNOON HOURS. CEILINGS WILL LOWER TO IFR AFTER A FEW HOURS OF RAIN. WINDS WILL SHIFT FROM NORTHEAST TO THE SOUTHEAST DURING THE DAY...WHICH COULD ALLOW FOR A BRIEF INCREASE OF WINDS AT KLBE DUE TO DOWNSLOPING. WINDS WILL BECOME SOUTHERLY ONCE THE WARM FRONT MOVES THROUGH THIS EVENING. .OUTLOOK.../MONDAY THROUGH THURSDAY/... MVFR AND PSBL IFR RESTRICTIONS WL CONTINUE WITH RAIN MONDAY AS A COLD FRONT MOVES THROUGH. MVFR CONDITIONS ARE EXPECTED MONDAY NIGHT INTO TUESDAY. LINGERING RAIN SHOWERS MAY CHANGE TO SCATTERED SNOW SHOWERS BEFORE ENDING EARLY TUESDAY. HIGH PRES AND VFR CONDS ARE EXPECTED LATER TUESDAY THROUGH THURSDAY. && .PBZ WATCHES/WARNINGS/ADVISORIES... MD...NONE. OH...NONE. PA...NONE. WV...NONE. && $$
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
957 AM EST SUN DEC 9 2012 .UPDATE... ISSUED AT 956 AM EST SUN DEC 9 2012 THE SOUTHWARD SHIFT OF THE MODELS OVER THE LAST 18-24HRS WITH THE SURFACE LOW AND IT TRANSFORMING INTO A SURFACE TROUGH TODAY HAS LED TO AN INTERESTING DECISION WITH RESPECT TO SOME OF THE HAZARDS. SNOW IS CURRENTLY SOUTHWEST OF A LINE FROM ASHLAND THROUGH MILWAUKEE. LATEST SHORT RANGE AND HIRES MODELS INDICATING BEST OPPORTUNITY FOR ADVISORY SNOW FROM THE SYSTEM ALONG THE WISCONSIN BORDER AND NEAR LAKE MICHIGAN WITH SOME LAKE ENHANCEMENT LATE THIS AFTERNOON THROUGH THE EVENING. AWAY FROM THIS AREA...VERY LOW CONFIDENCE IN SEEING ENOUGH SNOW FOR ADVISORY CRITERIA FOR SOME AREAS...ESPECIALLY FOR NORTHERN IRON...EASTERN GOGEBIC...SOUTHEAST ONTONAGON AND SOUTHERN HOUGHTON COUNTIES. THEY WILL BE ON THE EDGE OF THE BETTER SYSTEM SNOW AND AWAY FROM THE LAKE ENHANCED SNOW THAT MAY SAVE THE ADVISORY FOR OTHER PARTS OF THE CWA NEAR LAKE SUPERIOR. THE LAKE ENHANCEMENT WILL LIKELY INCREASE AFTER MIDNIGHT AS WINDS TURN TO THE NORTH-NORTHEAST AND FAVOR THE WESTERN SHORELINE FROM IRONWOOD THROUGH HOUGHTON AND THEN THE HIGHER TERRAIN OF EASTERN BARAGA AND NORTHERN MARQUETTE COUNTIES...AND POTENTIALLY FAR WESTERN ALGER COUNTY. THE MOST FAVORABLE PERIOD FOR LAKE ENHANCED SNOW WILL BE LATE TONIGHT INTO THE FIRST PART OF TOMORROW MORNING. BUT...WITH THE WINDS BACKING THROUGH TONIGHT AND MONDAY...THE OPPORTUNITY FOR MORE THAN A BRIEF 1-3 INCHES WILL BE LIMITED. BASED OFF LOCAL SNOW AND VEHICLE ACCIDENT DATA...EVEN SEEING 1IN OF SNOW GREATLY INCREASES ACCIDENTS IN THE AREA. THUS...EVEN THOUGH SOME OF THE MENTIONED AREAS OF CONCERN WILL LIKELY ONLY SEE 1-3IN OF SNOW...WILL LEAVE THE ADVISORY IN PLACE AT THIS POINT. MADE ADJUSTMENTS TO POPS AND SNOW AMOUNTS FOR TODAY TO BETTER MATCH LATEST MODEL RUNS. THIS RESULTED IN A REDUCTION OF SNOW AMOUNTS IN SOME AREAS OF AROUND 0.5-1.0IN. && .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 528 AM EST SUN DEC 9 2012 WV IMAGERY AND RUC ANALYSIS INDICATED A BROAD MID/UPPER LEVEL TROUGH FROM THE ROCKIES INTO THE CNTRL AND NRN PLAINS. A VIGOROUS SHORTWAVE TROUGH EXTENDED FROM CNTRL SOUTH DAKOTA INTO NRN NEBRASKA. UPSTREAM...ANOTHER SHRTWV WAS DIGGING SOUTHEAST INTO THE CNTRL ROCKIES. AT THE SFC...EASTERLY FLOW WAS INCREASING OVER THE REGION BTWN LOW PRES OVER SE SOUTH DAKOTA AND A RIDGE FROM SASK AND CNTRL MANITOBA INTO NRN ONTARIO. STRONG 700-300 MB QVECTOR CONV AHEAD OF THE SHORTWAVE ALONG WITH STEEP 700-500 MB LAPSE RATES FROM 7C TO 8C/KM SUPPORTED STRONG UPWARD MOTION AND AREAS OF MODERATE TO HEAVY SNOW OVER WRN INTO CNTRL MN WHERE THE LOW LEVEL MOISTURE INFLOW WAS MOST FAVORABLE. THE MODELS HAVE TRENDED SOUTHWARD WITH THE SHRTWV AND ASSOCIATED SFC LOW/TROUGH AS IT PROGRESSES TO THE EAST. SIMILAR TO PREVIOUS MODEL RUNS...THE SHRTWV ALSO SHEARS OUT AND WEAKENS AS IT MOVES TO THE NORTHEAST. IN ADDITION...THE DRY EASTERLY FLOW OUT OF ONTARIO INTO UPPER MI WILL HELP DELAY THE ONSET OF THE SNOW AND MAY HELP LOWER OVERALL SNOWFALL AMOUNTS. SO...WINTER WEATHER ADVISORY START TIMES WERE ADJUSTED ACCORDINGLY. THE STRONGEST 280K-290K ISENTROPIC LIFT AND 800-600 MB FGEN LATE THIS AFTERNOON AND EVENING IS EXPECTED CLOSEST TO THE SRN CWA...FROM NRN WI INTO NRN LAKE MI. MODELS QPF VALUES FROM 0.15 TO 0.40 INCH ARE STILL POSSIBLE AS THE AREA OF MODERATE TO STRONG QVECTOR CONV AND WAA/ISENTROPIC LIFT BRUSH THE CWA. WITH THE STRONGEST OMEGA REMAINING ABOVE THE DENDRITIC GROWTH ZONE FROM ABOUT 5K TO 9K FT...SNOW/WATER RATIOS SHOULD REMAIN AT OR BELOW 15/1. SYNOPTIC SNOWFALL AMOUNTS IN THE 2 TO 5 INCH RANGE ARE POSSIBLE MAINLY LATE THIS AFTERNOON AND THIS EVENING. THE WIDESPREAD SNOW SHOULD DIMINISH OVERNIGHT AS THE SHORTWAVE MOVES OFF TO THE NE AND WEAKENS. WITH 850 MB TEMPS AROUND -8C...THE HIGHER RES MODELS INDICATED THE POTENTIAL FOR BANDS OF LAKE ENHANCED SNOW DEVELOPING OFF OF LAKE MICHIGAN THAT MAY BOOST SNOW TOTALS FROM THE GARDEN PENINSULA TO ESC AND MNM. THERE IS LESS CONFIDENCE THAT THE ERLY FLOW INTO THE KEWEENAW WILL ADD TO SNOW AMOUNTS WITH THE STRONGER DYNAMICS TO THE SOUTH AND THE INFLUENCE OF THE DRY EAST FLOW. AS THE LOW LEVEL TROUGH SLIDES TO THE EAST...EXPECT CYCLONIC N TO NE FLOW TO BRING AN INCREASE IN LAKE EFFECT SNOW TO NEAR IWD AND N CNTRL UPPER MI LATE TONIGHT. .LONG TERM...(MONDAY THROUGH SATURDAY) ISSUED AT 528 AM EST SUN DEC 9 2012 SYNOPTIC FORCING WILL BE EAST OF THE AREA BY MONDAY MORNING. HOWEVER...NORTHERLY AND NORTHEASTERLY WINDS WILL ALLOW LAKE EFFECT TO LINGER INTO THE EARLY AFTERNOON HOURS. AS FLOW BECOMES MORE ANTICYCLONIC PARAMETERS DO NOT SUGGEST LAKE SNOWS WILL BE OVERLY HEAVY. THE BEST CHANCE FOR AN ADDITIONAL FEW INCHES OF SNOW WILL BE OVER NW ONTONAGON COUNTY AND WESTERN GOGEBIC COUNTY BASED PRIMARILY ON LONGER FETCH INTO THESE AREAS. THE HIGHER TERRAIN OF MARQUETTE COUNTY MAY ALSO PICKUP ANOTHER INCH OR TWO DURING THE MORNING. SNOW WILL BE ON THE WANE IN THESE AREAS THROUGH THE AFTERNOON. IT DOESNT APPEAR THAT ANY OTHER SIGNIFICANT STORMS WILL AFFECT THE UPPER GREAT LAKES THROUGH THE REMAINDER OF THE UPCOMING WORK WEEK. WEAK SURFACE RIDGE AXIS WILL CROSS THE AREA MONDAY NIGHT WITH WINDS BECOMING SOUTHERLY ACROSS THE AREA ON TUESDAY AS NEXT WEAK SHORTWAVE APPROACHES THE AREA. 85H TEMPS WILL REMAIN LOW ENOUGH -10 TO -12 FOR LES TO DEVELOP OFF LAKE MI. WITH THE PRIMARY BAND TRANSIENT ENOUGH EXPECT AMOUNTS TO ONLY BE IN THE 1 TO 3 INCH RANGE OVER SE SCHOOLCRAFT COUNTY INTO LUCE COUNTY. AS SURFACE TROF PASS THROUGH THE AREA LATE TUESDAY WINDS WILL BRIEFLY BECOME MORE WESTERLY WHICH MAY ALLOW FOR SOME LIGHT LES TO RETURN TO THE KEWEENAW. WINDS WILL THEN BACK SOUTHERLY AGAIN AS NEXT QUICK MOVING SHORTWAVE AND SURFACE LOW RACES EASTWARD ACROSS SOUTHERN ONTARIO ON THURSDAY. BEST FORCING FOR PRECIPITATION SHOULD GENERALLY REMAIN NORTH OF THE AREA. MEDIUM RANGE MODELS STILL INDICATING SOME POTENTIAL FOR A MORE SIGNIFICANT STORM FOR NEXT WEEKEND BUT CONFIDENCE IN ANY DETAILS ARE VERY LOW. AS SEEN WITH THE CHALLENGES OF OUR CURRENT SYSTEM WHERE THE INTERACTION OF NORTHERN AND SOUTHERN STREAM ENERGY WAS CRUCIAL TO THE FORECAST AND NOT RESOLVED UNTIL JUST PRIOR TO THE EVENT...TRYING TO GARNER ANY DETAILS ON A POTENTIAL SYSTEM A WEEK AWAY IS A LOW CONFIDENCE PROPOSITION. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z MONDAY MORNING) ISSUED AT 652 AM EST SUN DEC 9 2012 EXPECT PREDOMINANT VFR CONDITIONS THROUGH AT LEAST THIS MORNING AT ALL THE TAF SITES WITH A RIDGE OF HIGH PRES AND AXIS OF LOW LEVEL DRY AIR DOMINATING. THEN LATER TODAY...THE APPROACH OF LOW PRES WILL BRING SNOW AND LOWER CIGS/VSBYS SW-NE TO UPR MI. CONTINUED WITH TREND TOWARD A SLOWER ONSET OF SN/LOWER CONDITIONS BASED ON NUMERICAL MODEL TRENDS SHOWING A FARTHER S TRACK FOR THE LOW PRES AND MORE RESILIENT DRY AIR OVER THE NORTHERN GREAT LAKES. ALTHOUGH SAW IS FARTHER TO THE NE...UPSLOPE ESE WIND MIGHT RESULT IN AN EARLIER ARRIVAL OF THE PCPN/MVFR CIGS. BY EARLY EVNG...CONDITIONS SHOULD DETERIORATE TO IFR AT ALL 3 LOCATIONS AND CONTINUE OVERNIGHT. && .MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE) ISSUED AT 532 AM EST SUN DEC 9 2012 AN AREA OF LOW PRESSURE MOVING OUT OF SOUTHEAST SOUTH DAKOTA WILL MOVE THROUGH MN TODAY AND THEN MERGE WITH A LOW DEVELOPING IN THE GREAT LAKES TO LEAVE A TROUGH OVER NORTHERN WISCONSIN. THIS TROUGH WILL INCREASE WINDS OUT OF THE EAST AND THEN NORTHEAST TODAY AND TONIGHT. AT THIS TIME...THINKING WINDS WILL BE IN THE 20-30KT RANGE...ALTHOUGH THERE COULD BE A FEW GALE FORCE GUSTS TO 35KTS OVER THE WEST AS THE TROUGH SHARPENS LATE TONIGHT. BEHIND THIS FEATURE...A SERIES OF WEAK RIDGES AND TROUGHS WILL AFFECT LAKE SUPERIOR DURING THE REST OF THE WORK WEEK AND KEEP WINDS BELOW 25KTS. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... WINTER WEATHER ADVISORY FROM 3 PM THIS AFTERNOON TO 7 AM EST MONDAY FOR MIZ006-007-013-014-085. WINTER WEATHER ADVISORY UNTIL 7 AM EST /6 AM CST/ MONDAY FOR MIZ004-010-084. WINTER WEATHER ADVISORY FROM 3 PM THIS AFTERNOON TO 1 PM EST MONDAY FOR MIZ005. WINTER WEATHER ADVISORY UNTIL 5 PM EST /4 PM CST/ MONDAY FOR MIZ002-009. WINTER WEATHER ADVISORY FROM 1 PM THIS AFTERNOON TO 7 AM EST MONDAY FOR MIZ001-003. WINTER WEATHER ADVISORY UNTIL 3 AM CST MONDAY FOR MIZ011-012. LAKE SUPERIOR... NONE. LAKE MICHIGAN... NONE. && $$ UPDATE...SRF SHORT TERM...JLB LONG TERM...MZ AVIATION...JLB MARINE...JLB
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
657 AM EST SUN DEC 9 2012 .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 528 AM EST SUN DEC 9 2012 WV IMAGERY AND RUC ANALYSIS INDICATED A BROAD MID/UPPER LEVEL TROUGH FROM THE ROCKIES INTO THE CNTRL AND NRN PLAINS. A VIGOROUS SHORTWAVE TROUGH EXTENDED FROM CNTRL SOUTH DAKOTA INTO NRN NEBRASKA. UPSTREAM...ANOTHER SHRTWV WAS DIGGING SOUTHEAST INTO THE CNTRL ROCKIES. AT THE SFC...EASTERLY FLOW WAS INCREASING OVER THE REGION BTWN LOW PRES OVER SE SOUTH DAKOTA AND A RIDGE FROM SASK AND CNTRL MANITOBA INTO NRN ONTARIO. STRONG 700-300 MB QVECTOR CONV AHEAD OF THE SHORTWAVE ALONG WITH STEEP 700-500 MB LAPSE RATES FROM 7C TO 8C/KM SUPPORTED STRONG UPWARD MOTION AND AREAS OF MODERATE TO HEAVY SNOW OVER WRN INTO CNTRL MN WHERE THE LOW LEVEL MOISTURE INFLOW WAS MOST FAVORABLE. THE MODELS HAVE TRENDED SOUTHWARD WITH THE SHRTWV AND ASSOCIATED SFC LOW/TROUGH AS IT PROGRESSES TO THE EAST. SIMILAR TO PREVIOUS MODEL RUNS...THE SHRTWV ALSO SHEARS OUT AND WEAKENS AS IT MOVES TO THE NORTHEAST. IN ADDITION...THE DRY EASTERLY FLOW OUT OF ONTARIO INTO UPPER MI WILL HELP DELAY THE ONSET OF THE SNOW AND MAY HELP LOWER OVERALL SNOWFALL AMOUNTS. SO...WINTER WEATHER ADVISORY START TIMES WERE ADJUSTED ACCORDINGLY. THE STRONGEST 280K-290K ISENTROPIC LIFT AND 800-600 MB FGEN LATE THIS AFTERNOON AND EVENING IS EXPECTED CLOSEST TO THE SRN CWA...FROM NRN WI INTO NRN LAKE MI. MODELS QPF VALUES FROM 0.15 TO 0.40 INCH ARE STILL POSSIBLE AS THE AREA OF MODERATE TO STRONG QVECTOR CONV AND WAA/ISENTROPIC LIFT BRUSH THE CWA. WITH THE STRONGEST OMEGA REMAINING ABOVE THE DENDRITIC GROWTH ZONE FROM ABOUT 5K TO 9K FT...SNOW/WATER RATIOS SHOULD REMAIN AT OR BELOW 15/1. SYNOPTIC SNOWFALL AMOUNTS IN THE 2 TO 5 INCH RANGE ARE POSSIBLE MAINLY LATE THIS AFTERNOON AND THIS EVENING. THE WIDESPREAD SNOW SHOULD DIMINISH OVERNIGHT AS THE SHORTWAVE MOVES OFF TO THE NE AND WEAKENS. WITH 850 MB TEMPS AROUND -8C...THE HIGHER RES MODELS INDICATED THE POTENTIAL FOR BANDS OF LAKE ENHANCED SNOW DEVELOPING OFF OF LAKE MICHIGAN THAT MAY BOOST SNOW TOTALS FROM THE GARDEN PENINSULA TO ESC AND MNM. THERE IS LESS CONFIDENCE THAT THE ERLY FLOW INTO THE KEWEENAW WILL ADD TO SNOW AMOUNTS WITH THE STRONGER DYNAMICS TO THE SOUTH AND THE INFLUENCE OF THE DRY EAST FLOW. AS THE LOW LEVEL TROUGH SLIDES TO THE EAST...EXPECT CYCLONIC N TO NE FLOW TO BRING AN INCREASE IN LAKE EFFECT SNOW TO NEAR IWD AND N CNTRL UPPER MI LATE TONIGHT. .LONG TERM...(MONDAY THROUGH SATURDAY) ISSUED AT 528 AM EST SUN DEC 9 2012 SYNOPTIC FORCING WILL BE EAST OF THE AREA BY MONDAY MORNING. HOWEVER...NORTHERLY AND NORTHEASTERLY WINDS WILL ALLOW LAKE EFFECT TO LINGER INTO THE EARLY AFTERNOON HOURS. AS FLOW BECOMES MORE ANTICYCLONIC PARAMETERS DO NOT SUGGEST LAKE SNOWS WILL BE OVERLY HEAVY. THE BEST CHANCE FOR AN ADDITIONAL FEW INCHES OF SNOW WILL BE OVER NW ONTONAGON COUNTY AND WESTERN GOGEBIC COUNTY BASED PRIMARILY ON LONGER FETCH INTO THESE AREAS. THE HIGHER TERRAIN OF MARQUETTE COUNTY MAY ALSO PICKUP ANOTHER INCH OR TWO DURING THE MORNING. SNOW WILL BE ON THE WANE IN THESE AREAS THROUGH THE AFTERNOON. IT DOESNT APPEAR THAT ANY OTHER SIGNIFICANT STORMS WILL AFFECT THE UPPER GREAT LAKES THROUGH THE REMAINDER OF THE UPCOMING WORK WEEK. WEAK SURFACE RIDGE AXIS WILL CROSS THE AREA MONDAY NIGHT WITH WINDS BECOMING SOUTHERLY ACROSS THE AREA ON TUESDAY AS NEXT WEAK SHORTWAVE APPROACHES THE AREA. 85H TEMPS WILL REMAIN LOW ENOUGH -10 TO -12 FOR LES TO DEVELOP OFF LAKE MI. WITH THE PRIMARY BAND TRANSIENT ENOUGH EXPECT AMOUNTS TO ONLY BE IN THE 1 TO 3 INCH RANGE OVER SE SCHOOLCRAFT COUNTY INTO LUCE COUNTY. AS SURFACE TROF PASS THROUGH THE AREA LATE TUESDAY WINDS WILL BRIEFLY BECOME MORE WESTERLY WHICH MAY ALLOW FOR SOME LIGHT LES TO RETURN TO THE KEWEENAW. WINDS WILL THEN BACK SOUTHERLY AGAIN AS NEXT QUICK MOVING SHORTWAVE AND SURFACE LOW RACES EASTWARD ACROSS SOUTHERN ONTARIO ON THURSDAY. BEST FORCING FOR PRECIPITATION SHOULD GENERALLY REMAIN NORTH OF THE AREA. MEDIUM RANGE MODELS STILL INDICATING SOME POTENTIAL FOR A MORE SIGNIFICANT STORM FOR NEXT WEEKEND BUT CONFIDENCE IN ANY DETAILS ARE VERY LOW. AS SEEN WITH THE CHALLENGES OF OUR CURRENT SYSTEM WHERE THE INTERACTION OF NORTHERN AND SOUTHERN STREAM ENERGY WAS CRUCIAL TO THE FORECAST AND NOT RESOLVED UNTIL JUST PRIOR TO THE EVENT...TRYING TO GARNER ANY DETAILS ON A POTENTIAL SYSTEM A WEEK AWAY IS A LOW CONFIDENCE PROPOSITION. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z MONDAY MORNING) ISSUED AT 652 AM EST SUN DEC 9 2012 EXPECT PREDOMINANT VFR CONDITIONS THROUGH AT LEAST THIS MORNING AT ALL THE TAF SITES WITH A RIDGE OF HIGH PRES AND AXIS OF LOW LEVEL DRY AIR DOMINATING. THEN LATER TODAY...THE APPROACH OF LOW PRES WILL BRING SNOW AND LOWER CIGS/VSBYS SW-NE TO UPR MI. CONTINUED WITH TREND TOWARD A SLOWER ONSET OF SN/LOWER CONDITIONS BASED ON NUMERICAL MODEL TRENDS SHOWING A FARTHER S TRACK FOR THE LOW PRES AND MORE RESILIENT DRY AIR OVER THE NORTHERN GREAT LAKES. ALTHOUGH SAW IS FARTHER TO THE NE...UPSLOPE ESE WIND MIGHT RESULT IN AN EARLIER ARRIVAL OF THE PCPN/MVFR CIGS. BY EARLY EVNG...CONDITIONS SHOULD DETERIORATE TO IFR AT ALL 3 LOCATIONS AND CONTINUE OVERNIGHT. && .MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE) ISSUED AT 532 AM EST SUN DEC 9 2012 AN AREA OF LOW PRESSURE MOVING OUT OF SOUTHEAST SOUTH DAKOTA WILL MOVE THROUGH MN TODAY AND THEN MERGE WITH A LOW DEVELOPING IN THE GREAT LAKES TO LEAVE A TROUGH OVER NORTHERN WISCONSIN. THIS TROUGH WILL INCREASE WINDS OUT OF THE EAST AND THEN NORTHEAST TODAY AND TONIGHT. AT THIS TIME...THINKING WINDS WILL BE IN THE 20-30KT RANGE...ALTHOUGH THERE COULD BE A FEW GALE FORCE GUSTS TO 35KTS OVER THE WEST AS THE TROUGH SHARPENS LATE TONIGHT. BEHIND THIS FEATURE...A SERIES OF WEAK RIDGES AND TROUGHS WILL AFFECT LAKE SUPERIOR DURING THE REST OF THE WORK WEEK AND KEEP WINDS BELOW 25KTS. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... WINTER WEATHER ADVISORY FROM 3 PM THIS AFTERNOON TO 7 AM EST MONDAY FOR MIZ006-007-013-014-085. WINTER WEATHER ADVISORY FROM NOON EST /11 AM CST/ TODAY TO 7 AM EST /6 AM CST/ MONDAY FOR MIZ004-010-084. WINTER WEATHER ADVISORY FROM 3 PM THIS AFTERNOON TO 1 PM EST MONDAY FOR MIZ005. WINTER WEATHER ADVISORY FROM 10 AM EST /9 AM CST/ THIS MORNING TO 5 PM EST /4 PM CST/ MONDAY FOR MIZ002-009. WINTER WEATHER ADVISORY FROM 1 PM THIS AFTERNOON TO 7 AM EST MONDAY FOR MIZ001-003. WINTER WEATHER ADVISORY FROM 11 AM THIS MORNING TO 3 AM CST MONDAY FOR MIZ011-012. LAKE SUPERIOR... NONE. LAKE MICHIGAN... NONE. && $$ SHORT TERM...JLB LONG TERM...MZ AVIATION...JLB MARINE...JLB
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
533 AM EST SUN DEC 9 2012 .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 528 AM EST SUN DEC 9 2012 WV IMAGERY AND RUC ANALYSIS INDICATED A BROAD MID/UPPER LEVEL TROUGH FROM THE ROCKIES INTO THE CNTRL AND NRN PLAINS. A VIGOROUS SHORTWAVE TROUGH EXTENDED FROM CNTRL SOUTH DAKOTA INTO NRN NEBRASKA. UPSTREAM...ANOTHER SHRTWV WAS DIGGING SOUTHEAST INTO THE CNTRL ROCKIES. AT THE SFC...EASTERLY FLOW WAS INCREASING OVER THE REGION BTWN LOW PRES OVER SE SOUTH DAKOTA AND A RIDGE FROM SASK AND CNTRL MANITOBA INTO NRN ONTARIO. STRONG 700-300 MB QVECTOR CONV AHEAD OF THE SHORTWAVE ALONG WITH STEEP 700-500 MB LAPSE RATES FROM 7C TO 8C/KM SUPPORTED STRONG UPWARD MOTION AND AREAS OF MODERATE TO HEAVY SNOW OVER WRN INTO CNTRL MN WHERE THE LOW LEVEL MOISTURE INFLOW WAS MOST FAVORABLE. THE MODELS HAVE TRENDED SOUTHWARD WITH THE SHRTWV AND ASSOCIATED SFC LOW/TROUGH AS IT PROGRESSES TO THE EAST. SIMILAR TO PREVIOUS MODEL RUNS...THE SHRTWV ALSO SHEARS OUT AND WEAKENS AS IT MOVES TO THE NORTHEAST. IN ADDITION...THE DRY EASTERLY FLOW OUT OF ONTARIO INTO UPPER MI WILL HELP DELAY THE ONSET OF THE SNOW AND MAY HELP LOWER OVERALL SNOWFALL AMOUNTS. SO...WINTER WEATHER ADVISORY START TIMES WERE ADJUSTED ACCORDINGLY. THE STRONGEST 280K-290K ISENTROPIC LIFT AND 800-600 MB FGEN LATE THIS AFTERNOON AND EVENING IS EXPECTED CLOSEST TO THE SRN CWA...FROM NRN WI INTO NRN LAKE MI. MODELS QPF VALUES FROM 0.15 TO 0.40 INCH ARE STILL POSSIBLE AS THE AREA OF MODERATE TO STRONG QVECTOR CONV AND WAA/ISENTROPIC LIFT BRUSH THE CWA. WITH THE STRONGEST OMEGA REMAINING ABOVE THE DENDRITIC GROWTH ZONE FROM ABOUT 5K TO 9K FT...SNOW/WATER RATIOS SHOULD REMAIN AT OR BELOW 15/1. SYNOPTIC SNOWFALL AMOUNTS IN THE 2 TO 5 INCH RANGE ARE POSSIBLE MAINLY LATE THIS AFTERNOON AND THIS EVENING. THE WIDESPREAD SNOW SHOULD DIMINISH OVERNIGHT AS THE SHORTWAVE MOVES OFF TO THE NE AND WEAKENS. WITH 850 MB TEMPS AROUND -8C...THE HIGHER RES MODELS INDICATED THE POTENTIAL FOR BANDS OF LAKE ENHANCED SNOW DEVELOPING OFF OF LAKE MICHIGAN THAT MAY BOOST SNOW TOTALS FROM THE GARDEN PENINSULA TO ESC AND MNM. THERE IS LESS CONFIDENCE THAT THE ERLY FLOW INTO THE KEWEENAW WILL ADD TO SNOW AMOUNTS WITH THE STRONGER DYNAMICS TO THE SOUTH AND THE INFLUENCE OF THE DRY EAST FLOW. AS THE LOW LEVEL TROUGH SLIDES TO THE EAST...EXPECT CYCLONIC N TO NE FLOW TO BRING AN INCREASE IN LAKE EFFECT SNOW TO NEAR IWD AND N CNTRL UPPER MI LATE TONIGHT. .LONG TERM...(MONDAY THROUGH SATURDAY) ISSUED AT 528 AM EST SUN DEC 9 2012 SYNOPTIC FORCING WILL BE EAST OF THE AREA BY MONDAY MORNING. HOWEVER...NORTHERLY AND NORTHEASTERLY WINDS WILL ALLOW LAKE EFFECT TO LINGER INTO THE EARLY AFTERNOON HOURS. AS FLOW BECOMES MORE ANTICYCLONIC PARAMETERS DO NOT SUGGEST LAKE SNOWS WILL BE OVERLY HEAVY. THE BEST CHANCE FOR AN ADDITIONAL FEW INCHES OF SNOW WILL BE OVER NW ONTONAGON COUNTY AND WESTERN GOGEBIC COUNTY BASED PRIMARILY ON LONGER FETCH INTO THESE AREAS. THE HIGHER TERRAIN OF MARQUETTE COUNTY MAY ALSO PICKUP ANOTHER INCH OR TWO DURING THE MORNING. SNOW WILL BE ON THE WANE IN THESE AREAS THROUGH THE AFTERNOON. IT DOESNT APPEAR THAT ANY OTHER SIGNIFICANT STORMS WILL AFFECT THE UPPER GREAT LAKES THROUGH THE REMAINDER OF THE UPCOMING WORK WEEK. WEAK SURFACE RIDGE AXIS WILL CROSS THE AREA MONDAY NIGHT WITH WINDS BECOMING SOUTHERLY ACROSS THE AREA ON TUESDAY AS NEXT WEAK SHORTWAVE APPROACHES THE AREA. 85H TEMPS WILL REMAIN LOW ENOUGH -10 TO -12 FOR LES TO DEVELOP OFF LAKE MI. WITH THE PRIMARY BAND TRANSIENT ENOUGH EXPECT AMOUNTS TO ONLY BE IN THE 1 TO 3 INCH RANGE OVER SE SCHOOLCRAFT COUNTY INTO LUCE COUNTY. AS SURFACE TROF PASS THROUGH THE AREA LATE TUESDAY WINDS WILL BRIEFLY BECOME MORE WESTERLY WHICH MAY ALLOW FOR SOME LIGHT LES TO RETURN TO THE KEWEENAW. WINDS WILL THEN BACK SOUTHERLY AGAIN AS NEXT QUICK MOVING SHORTWAVE AND SURFACE LOW RACES EASTWARD ACROSS SOUTHERN ONTARIO ON THURSDAY. BEST FORCING FOR PRECIPITATION SHOULD GENERALLY REMAIN NORTH OF THE AREA. MEDIUM RANGE MODELS STILL INDICATING SOME POTENTIAL FOR A MORE SIGNIFICANT STORM FOR NEXT WEEKEND BUT CONFIDENCE IN ANY DETAILS ARE VERY LOW. AS SEEN WITH THE CHALLENGES OF OUR CURRENT SYSTEM WHERE THE INTERACTION OF NORTHERN AND SOUTHERN STREAM ENERGY WAS CRUCIAL TO THE FORECAST AND NOT RESOLVED UNTIL JUST PRIOR TO THE EVENT...TRYING TO GARNER ANY DETAILS ON A POTENTIAL SYSTEM A WEEK AWAY IS A LOW CONFIDENCE PROPOSITION. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z MONDAY MORNING) ISSUED AT 1239 AM EST SUN DEC 9 2012 EXPECT PREDOMINANT VFR CONDITIONS THRU AT LEAST THIS MRNG AT ALL THE TAF SITES WITH RDG OF HI PRES/AXIS OF LLVL DRY AIR DOMINATING. THEN LATER TODAY...APRCH OF LO PRES WL BRING SN AND LOWER CIGS/VSBYS SW-NE TO UPR MI. TENDED TO SLOW DOWN THE ONSET OF SN/LOWER CONDITIONS BASED ON NUMERICAL MODEL TRENDS SHOWING A FARTHER S TRACK FOR THE LO PRES/MORE RESILIENT DRY AIR OVER THE UPR LKS. ALTHOUGH SAW IS FARTHER TO THE NE...UPSLOPE ESE WIND MIGHT RESULT IN AN EARLIER ARRIVAL OF THE PCPN/MVFR CIGS. BY EARLY EVNG...CONDITIONS SHOULD DETERIORATE TO IFR AT ALL 3 LOCATIONS. && .MARINE...(FOR THE 4 AM LAKE SUPERIOR FORECAST ISSUANCE) ISSUED AT 532 AM EST SUN DEC 9 2012 AN AREA OF LOW PRESSURE MOVING OUT OF SOUTHEAST SOUTH DAKOTA WILL MOVE THROUGH MN TODAY AND THEN MERGE WITH A LOW DEVELOPING IN THE GREAT LAKES TO LEAVE A TROUGH OVER NORTHERN WISCONSIN. THIS TROUGH WILL INCREASE WINDS OUT OF THE EAST AND THEN NORTHEAST TODAY AND TONIGHT. AT THIS TIME...THINKING WINDS WILL BE IN THE 20-30KT RANGE...ALTHOUGH THERE COULD BE A FEW GALE FORCE GUSTS TO 35KTS OVER THE WEST AS THE TROUGH SHARPENS LATE TONIGHT. BEHIND THIS FEATURE...A SERIES OF WEAK RIDGES AND TROUGHS WILL AFFECT LAKE SUPERIOR DURING THE REST OF THE WORK WEEK AND KEEP WINDS BELOW 25KTS. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... WINTER WEATHER ADVISORY FROM 3 PM THIS AFTERNOON TO 7 AM EST MONDAY FOR MIZ006-007-013-014-085. WINTER WEATHER ADVISORY FROM NOON EST /11 AM CST/ TODAY TO 7 AM EST /6 AM CST/ MONDAY FOR MIZ004-010-084. WINTER WEATHER ADVISORY FROM 3 PM THIS AFTERNOON TO 1 PM EST MONDAY FOR MIZ005. WINTER WEATHER ADVISORY FROM 10 AM EST /9 AM CST/ THIS MORNING TO 5 PM EST /4 PM CST/ MONDAY FOR MIZ002-009. WINTER WEATHER ADVISORY FROM 1 PM THIS AFTERNOON TO 7 AM EST MONDAY FOR MIZ001-003. WINTER WEATHER ADVISORY FROM 11 AM THIS MORNING TO 3 AM CST MONDAY FOR MIZ011-012. LAKE SUPERIOR... NONE. LAKE MICHIGAN... NONE. && $$ SHORT TERM...JLB LONG TERM...MZ AVIATION...JLB MARINE...JLB
AREA FORECAST DISCUSSION
NWS TWIN CITIES/CHANHASSEN MN
539 AM CST SUN DEC 9 2012 .DISCUSSION... OVERVIEW...UPDATED FORECAST TO ACCOUNT FOR SOUTHERLY SHIFT OF WINTER STORM AFFECTING THE AREA TODAY. THIS PUTS THE TWIN CITIES METRO AREA RIGHT IN THE SWATH OF HEAVIEST SNOWFALL. MINOR ADJUSTMENTS TO THE WINTER WEATHER HEADLINES OVERNIGHT. ADDED MCLEOD AND MEEKER COUNTIES TO THE BLIZZARD WARNING AND LE SUEUR...RICE AND GOODHUE TO THE WINTER STORM WARNING. FRESH SNOW COVER MIGHT KEEP US A BIT COOLER THAN FORECAST TEMPERATURES THIS WEEK. NO MAJOR CHANGES TO FORECAST BEYOND THIS WEEKEND. BEEN WATCHING PERSISTENT LIGHT TO MODERATE SNOWFALL ACROSS MINNESOTA FOR THE LAST 4 TO 5 HOURS NOW. AIRPORTS REPORTING MAINLY REPORTING 3/4SM TO 1 1/2SM VISIBILITY AND A LOT OF AREA HAVE PICKED UP AND INCH OR TWO OF SNOW. FINALLY...STARTING TO GET SITES MEASURE IN WISCONSIN...BUT REALLY AREN`T SEEING MUCH HEAVY SNOW OUT THERE EARLY THIS MORNING AFTER THE INITIAL BAND NEAR THE MN/SD BORDER BROKE UP AROUND MIDNIGHT. SNOW RATES IN YELLOW MEDICINE AND LAC QUI PARLE WERE NEAR AN INCH PER HOUR LAST EVENING...WITH SITES NEAR THE STATE LINE QUICKLY PICKING UP 4-5" IN A FEW HOURS TIME. THE 00Z MPX SOUNDING...ALONG FSD AND ABR VAD PROFILES SHOW A STRONG WAA REGIME...WHICH SHOULD BE ENHANCED BY THE APPROACHING UPPER TROUGH AND INCREASING MID- LEVEL FRONTAL-GENESIS. CONSEQUENTLY...THIS BAND IS EXPECTED TO PERSIST INTO SWRN MN...FAR NERN SD...AND FAR SERN ND. SNOWFALL RATES ARE GENERALLY EXPECTED TO REMAIN BELOW 1 INCH/HOUR BUT BRIEF/ISOLATED RATES GREATER THAN 1 INCH/HOUR ARE POSSIBLE. THERE WAS GOOD MODEL CONSENSUS AMONG THE 09.00Z RUNS OF A SLIGHT SOUTHWARD SHIFT TO THE SURFACE LOW TRACK. THE RAP13 AND 00Z NAM WERE THE FIRST TO SUGGEST THIS AND THE 00Z GFS CAME ALMOST PERFECTLY IN LINE WITH THE NAM. WHAT IS A CONCERN IS THE ALMOST IDENTICAL PLACEMENT OF 14-16" SNOWFALL IN THE WEST TWIN CITIES METRO AND COUNTIES JUST WEST OF HERE. 09.00Z LOCAL WRF-ARW AND 09.08Z RAP ALSO HAVE HIGH END SNOWFALL RIGHT IN THE CENTER OF OUR CWA GIVEN THE SLOW MOVEMENT AND TRACK OF THE SURFACE/850MB/700MB LOW CENTERS. THE RAP HAS 20 INCHES...LIKELY OVERDONE BUT IT`S HINTING AT THE POTENTIAL FOR SOMETHING SIGNIFICANT. THE PV FEATURE ASSOCIATED WITH THIS SYSTEM IS IMPRESSIVE AND ITS ORIENTATION SUGGESTS A LONGER THAN EXPECTED PERIOD OF SNOW TODAY. ALREADY SEEING EVIDENCE OF A CIRCULATION IN THE REFLECTIVITY ACROSS SW MN. THIS SHOULD FEATURE SHOULD LIFT NORTH...BECOME ANCHORED PRODUCE 0.75-1.5" SNOWFALL RATES LATE THIS MORNING AND EARLY THIS AFTERNOON. INCREASED THE SNOWFALL IN THE TWIN CITIES METRO TO 8-11 INCHES...AND HOPEFULLY THAT IS ENOUGH TO COVER IT. DEPTH OF SNOW GROWTH REGION ISN`T OVERLY IMPRESSIVE...BUT WE SHOULD STILL MANAGE SNOW RATIOS NEAR CLIMATOLOGY 13-14:1 OR SO. FURTHERMORE...ON THE NOSE OF THE PV FEATURE...JUST AHEAD OF DRY SLOT...STATIC STABILITY BECOMES WEAK AND SUGGESTS BANDED PRECIP COULD BE FACTORING IN TO HELP SNOW TOTALS. OTHERWISE...WARMED TEMPS TONIGHT WITH THE SLOWER PROGRESSION AND KEPT THE WIND ABOUT THE SAME...PERHAPS A BIT LESS. THEREFORE WIND CHILLS AREN`T AS COLD WITH THIS MORNING`S FORECAST. IN THE EXTENDED...HEIGHTS BEGIN TO BUILD BACK ON WEDNESDAY...SO SHOULD ALREADY SEE MODERATING TEMPS FROM A COLD MONDAY AND TUESDAY. A COUPLE WEAK CLIPPER SYSTEM LOOK TO PASS NORTH OF THE AREA THIS WEEK...BUT THERE IS ANOTHER POTENTIALLY SIGNIFICANT STORM ON THE HORIZON 6-7 DAYS FROM NOW. && .AVIATION.../12Z TAF ISSUANCE/ OVER THE NEXT 6 HRS...CONDS WILL DETERIORATE RAPIDLY WITH MOST TAF SITES GOING TO NEAR MINIMUMS. STORM SYSTEM WAS BEGINNING TO DEVELOP A STRONG CIRCULATION NORTHWEST OF KFSD WITH A LARGE AREA OF ENERGY THAT WILL LIFT TO THE E/NE DURING THE MORNING. SNOWFALL RATES WILL LIKELY INCREASE TO 1...OR EVEN 2 INCHES PER HOUR DURING THE HEIGHT OF THE STORM. TAFS ARE BASED ON CURRENT RAP MODEL SFC WINDS AND FORECAST REFLECTIVITY OF THE SPC/WRF. AXN WILL LIKELY BE ON THE NW SIDE OF THE LOWEST CIGS/VSBYS...WITH STC/RNH/MSP LIKELY THE WORSE AREA DURING THE 15-03Z TIME FRAME. AS THE STORM SYSTEM MOVES EASTWARD ACROSS SOUTHERN MN TODAY...EXPECT A BAND OF MODERATE TO HEAVY SNOWFALL ALONG A LINE FROM KMVE TO KMGG TO KOEO. AS THE STORM BEGINS TO PIVOT...EXPECT THE BANDS OF SNOW TO SLOWLY MOVE FROM THE WEST TO THE EAST...THEN SE AS THE STORM MOVES OFF TO THE WESTERN GREAT LAKES. THERE WILL BE A PERIOD OF 1/4SM +SN AND VV002 OR LOWER. EXPECT SFC WINDS TO INCREASE AT AXN BY 15-18Z...THAN AT RWF BY 18-21Z. AFT 00-03Z CONDS WILL SLOWLY IMPROVE WITH IFR...OR MVFR CIGS/VSBYS WITH BLSN CONTINUING ACROSS AXN/RWF. KMSP... THERE IS A 3 HR PERIOD OF IFR/MVFR CONDS WITH -SN...BUT AFT 15Z EXPECT CONDS TO DETERIORATE RAPIDLY WITH VSBYS DROPPING TO LESS THAN 3/4SM AND CIGS LOWERING TO 500` OR EVEN LOWER. THERE IS A PERIOD DURING THE AFTN WHERE VSBYS COULD DROP TO 1/4SM +SN AND VV002. SFC WINDS WILL BE PREDOMINATE FROM THE E/SE THIS MORNING/AFTN WITH SOME GUSTS OVER 20 KTS POSSIBLE BY MID MORNING. WINDS WILL SHIFT TO THE E/NE AFT 21Z...THEN BECOME N/NNE BY 00-03Z AND GUSTY. EVENTUALLY WINDS WILL SHIFT TO THE N/NNW AFT 06Z WITH CIGS/VSBYS SLOWLY IMPROVING. DECIDED NOT TO INCLUDE A TEMPORARY GROUP DUE TO UNCERTAINTIES OF TIMING OF WHEN THE WORSE CONDS DEVELOP THIS MORNING/AFTN. TAFS WILL LIKELY BE AMD AS THIS SYSTEM EVOLVES. /OUTLOOK FOR KMSP/ MON...MVFR/IFR CIGS POSSIBLE EARLY. THEN VFR. WINDS WNW AT 10G15KTS. TUE...MVFR/IFR CIGS POSSIBLE. FLURRIES. WINDS SW AT 10G15KTS. WED...MVFR/IFR CIGS POSSIBLE EARLY. WINDS S AT 10KTS. ..JLT.. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...WINTER STORM WARNING UNTIL MIDNIGHT CST TONIGHT FOR ANOKA-BENTON- CARVER-CHISAGO-DAKOTA-GOODHUE-HENNEPIN-ISANTI-KANABEC-LE SUEUR-MILLE LACS-MORRISON-RAMSEY-RICE-SCOTT-SHERBURNE- STEARNS-TODD-WASHINGTON-WRIGHT. WINTER STORM WARNING UNTIL 11 AM CST THIS MORNING FOR CHIPPEWA- DOUGLAS-KANDIYOHI-LAC QUI PARLE-MCLEOD-MEEKER-POPE-RENVILLE- SIBLEY-STEVENS-SWIFT-YELLOW MEDICINE. BLIZZARD WARNING FROM 11 AM THIS MORNING TO MIDNIGHT CST TONIGHT FOR BROWN-CHIPPEWA-DOUGLAS-KANDIYOHI-LAC QUI PARLE-MCLEOD- MEEKER-NICOLLET-POPE-REDWOOD-RENVILLE-SIBLEY-STEVENS-SWIFT- YELLOW MEDICINE. WINTER WEATHER ADVISORY UNTIL MIDNIGHT CST TONIGHT FOR BLUE EARTH-FARIBAULT-FREEBORN-MARTIN-STEELE-WASECA-WATONWAN. WINTER WEATHER ADVISORY UNTIL 11 AM CST THIS MORNING FOR BROWN- NICOLLET-REDWOOD. WI...WINTER STORM WARNING UNTIL MIDNIGHT CST TONIGHT FOR BARRON- CHIPPEWA-DUNN-EAU CLAIRE-PEPIN-PIERCE-POLK-RUSK-ST. CROIX. && $$ CLF/JLT
AREA FORECAST DISCUSSION
NWS TWIN CITIES/CHANHASSEN MN
413 AM CST SUN DEC 9 2012 .DISCUSSION... OVERVIEW...UPDATED FORECAST TO ACCOUNT FOR SOUTHERLY SHIFT OF WINTER STORM AFFECTING THE AREA TODAY. THIS PUTS THE TWIN CITIES METRO AREA RIGHT IN THE SWATH OF HEAVIEST SNOWFALL. MINOR ADJUSTMENTS TO THE WINTER WEATHER HEADLINES OVERNIGHT. ADDED MCLEOD AND MEEKER COUNTIES TO THE BLIZZARD WARNING AND LE SUEUR...RICE AND GOODHUE TO THE WINTER STORM WARNING. FRESH SNOW COVER MIGHT KEEP US A BIT COOLER THAN FORECASTED TEMPERATURES THIS WEEK. NO MAJOR CHANGES TO FORECAST BEYOND THIS WEEKEND. BEEN WATCHING PERSISTENT LIGHT TO MODERATE SNOWFALL ACROSS MINNESOTA FOR THE LAST 4 TO 5 HOURS NOW. AIRPORTS REPORTING MAINLY REPORTING 3/4SM TO 1 1/2SM VISIBILITY AND A LOT OF AREA HAVE PICKED UP AND INCH OR TWO OF SNOW. FINALLY...STARTING TO GET SITES MEASURE IN WISCONSIN...BUT REALLY AREN`T SEEING MUCH HEAVY SNOW OUT THERE EARLY THIS MORNING AFTER THE INITIAL BAND NEAR THE MN/SD BORDER BROKE UP AROUND MIDNIGHT. SNOW RATES IN YELLOW MEDICINE AND LAC QUI PARLE WERE NEAR AN INCH PER HOUR LAST EVENING...WITH SITES NEAR THE STATE LINE QUICKLY PICKING UP 4-5" IN A FEW HOURS TIME. THE 00Z MPX SOUNDING...ALONG FSD AND ABR VAD PROFILES SHOW A STRONG WAA REGIME...WHICH SHOULD BE ENHANCED BY THE APPROACHING UPPER TROUGH AND INCREASING MID- LEVEL FRONTOGENESIS. CONSEQUENTLY...THIS BAND IS EXPECTED TO PERSIST INTO SWRN MN...FAR NERN SD...AND FAR SERN ND. SNOWFALL RATES ARE GENERALLY EXPECTED TO REMAIN BELOW 1 INCH/HOUR BUT BRIEF/ISOLATED RATES GREATER THAN 1 INCH/HOUR ARE POSSIBLE. THERE WAS GOOD MODEL CONSENSUS AMONG THE 09.00Z RUNS OF A SLIGHT SOUTHWARD SHIFT TO THE SURFACE LOW TRACK. THE RAP13 AND 00Z NAM WERE THE FIRST TO SUGGEST THIS AND THE 00Z GFS CAME ALMOST PERFECTLY IN LINE WITH THE NAM. WHAT IS A CONCERN IS THE ALMOST IDENTICAL PLACEMENT OF 14-16" SNOWFALL IN THE WEST TWIN CITIES METRO AND COUNTIES JUST WEST OF HERE. 09.00Z LOCAL WRF-ARW AND 09.08Z RAP ALSO HAVE HIGH END SNOWFALL RIGHT IN THE CENTER OF OUR CWA GIVEN THE SLOW MOVEMENT AND TRACK OF THE SURFACE/850MB/700MB LOW CENTERS. THE RAP HAS 20 INCHES...LIKELY OVERDONE BUT IT`S HINTING AT THE POTENTIAL FOR SOMETHING SIGNIFICANT. THE PV FEATURE ASSOCIATED WITH THIS SYSTEM IS IMPRESSIVE AND ITS ORIENTATION SUGGESTS A LONGER THAN EXPECTED PERIOD OF SNOW TODAY. ALREADY SEEING EVIDENCE OF A CIRCULATION IN THE REFLECTIVITY ACROSS SW MN. THIS SHOULD FEATURE SHOULD LIFT NORTH...BECOME ANCHORED PRODUCE 0.75-1.5" SNOWFALL RATES LATE THIS MORNING AND EARLY THIS AFTERNOON. INCREASED THE SNOWFALL IN THE TWIN CITIES METRO TO 8-11 INCHES...AND HOPEFULLY THAT IS ENOUGH TO COVER IT. DEPTH OF SNOW GROWTH REGION ISN`T OVERLY IMPRESSIVE...BUT WE SHOULD STILL MANAGE SNOW RATIOS NEAR CLIMATOLOGY 13-14:1 OR SO. FURTHERMORE...ON THE NOSE OF THE PV FEATURE...JUST AHEAD OF DRY SLOT...STATIC STABILITY BECOMES WEAK AND SUGGESTS BANDED PRECIP COULD BE FACTORING IN TO HELP SNOW TOTALS. OTHERWISE...WARMED TEMPS TONIGHT WITH THE SLOWER PROGRESSION AND KEPT THE WIND ABOUT THE SAME...PERHAPS A BIT LESS. THEREFORE WIND CHILLS AREN`T AS COLD WITH THIS MORNING`S FORECAST. IN THE EXTENDED...HEIGHTS BEGIN TO BUILD BACK ON WEDNESDAY...SO SHOULD ALREADY SEE MODERATING TEMPS FROM A COLD MONDAY AND TUESDAY. A COUPLE WEAK CLIPPER SYSTEM LOOK TO PASS NORTH OF THE AREA THIS WEEK...BUT THERE IS ANOTHER POTENTIALLY SIGNIFICANT STORM ON THE HORIZON 6-7 DAYS FROM NOW. && .AVIATION.../06Z TAF ISSUANCE/ SIGNIFICANT SOUTHERN SHIFT ALONG WITH A BIT OF A SLOWING OCCURRED WITH 00Z MODEL RUNS AND THIS PLACES ALL MPX TERMINALS WITHIN THE HEART OF WHAT LOOKS TO BE AN IMPRESSIVE SNOW BAND...WITH 6-10 INCH SNOW TOTALS /AND POSSIBLY MORE AT STC...MSP...RNH/ NOW EXPECTED. SFC LOW RIGHT NOW IS CENTERED ALONG I-90 NEAR CHAMBERLAIN...SD. 00Z NAM/GFS ALONG WITH THE RAP TRACK THIS LOW RIGHT DOWN I-90 THROUGH THE DAY SUNDAY...PLACING THE MPX TERMINALS WITHIN THE HEAVIEST SNOW. HAVE ALREADY BEEN GETTING SNOWFALL RATES OF AN INCH PLUS PER HOUR IN WRN MN...SO CONTINUED TO ADVERTISE PROLONGED PERIODS OF 1/2SM VIS AT ALL TERMINALS...BUT TENDED TO SHIFT THAT MENTION OUT IN TIME WITH THE SLOWING. ANOTHER ASPECT OF THE SLOWING WAS THE NEED TO SLOW THE BACKING OF WINDS FROM THE EAST OVER TO THE NW...ALONG WITH A TEMPERING OF SPEEDS SOME...AS NAM NOW SHOWING GUST POTENTIAL GREATER THAN 35 KTS AT ONLY RWF. AS THIS TAF PERIOD COMES TO AN END...CLEARING WILL START WORKING INTO WRN MN...WITH VFR CONDITIONS EXPECTED AS WE START GOING A LITTLE BEYOND THIS TAF PERIOD. KMSP...ALL GUIDANCE NOW PUTTING MSP IN THE CROSS-HAIRS FOR THE HEAVIEST SNOW WITH THIS EVENT...SO SIGNIFICANTLY DEGRADED TAF...WITH LIFR VIS SNOW NOW EXTENDING WELL OUT INTO THE AFTERNOON. LOOKING AT THE NAM ALONG WITH CURRENT RADAR...EXPECTING TWO BURSTS OF SNOW THIS PERIOD. FIRST WILL COME BETWEEN 8Z AND 12Z AS WARM ADVECTIVE WING OF PRECIP SWINGS THROUGH...WITH THE NEXT...MORE PROLONGED BOUT OF HEAVY SNOW HITTING BETWEEN 14Z AND 22Z AS THE MAIN UPPER FORCING MOVES IN. THIS IS WHEN MAJORITY OF ACCUMULATIONS SHOULD OCCUR...WITH SEVERAL OF THESE HOURS LIKELY SEEING RATES AROUND 1 INCH AN HOUR. THIS TAF MAY A BIT PESSIMISTIC WITH THE LENGTH OF 1/2SM VIS...BUT FEEL PRETTY CONFIDENT IN WINDOWS OF HEAVIER SNOW THAT ARE INDICATED WITH TAF. AVIATION WEATHER WARNING WILL ALSO BE ISSUED SHORTLY FOR ACCUMULATIONS EXCEEDING 3/4 OF AN INCH PER HOUR. AS FOR STORM TOTAL...WOULD PUT MSP ON THE HIGHER END OF THE SCALE WITH 8-10 INCHES LOOKING MORE AND MORE LIKELY. /OUTLOOK FOR KMSP/ MON...MVFR/IFR CIGS POSSIBLE EARLY. THEN VFR. WINDS WNW AT 10G15KTS. TUE...MVFR/IFR CIGS POSSIBLE. WINDS SW AT 10G15KTS. WED...VFR. WINDS SE AT 10KTS. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...WINTER STORM WARNING UNTIL MIDNIGHT CST TONIGHT FOR ANOKA-BENTON- CARVER-CHISAGO-DAKOTA-GOODHUE-HENNEPIN-ISANTI-KANABEC-LE SUEUR-MILLE LACS-MORRISON-RAMSEY-RICE-SCOTT-SHERBURNE- STEARNS-TODD-WASHINGTON-WRIGHT. WINTER STORM WARNING UNTIL 11 AM CST THIS MORNING FOR CHIPPEWA- DOUGLAS-KANDIYOHI-LAC QUI PARLE-MCLEOD-MEEKER-POPE-RENVILLE- SIBLEY-STEVENS-SWIFT-YELLOW MEDICINE. BLIZZARD WARNING FROM 11 AM THIS MORNING TO MIDNIGHT CST TONIGHT FOR BROWN-CHIPPEWA-DOUGLAS-KANDIYOHI-LAC QUI PARLE-MCLEOD- MEEKER-NICOLLET-POPE-REDWOOD-RENVILLE-SIBLEY-STEVENS-SWIFT- YELLOW MEDICINE. WINTER WEATHER ADVISORY UNTIL MIDNIGHT CST TONIGHT FOR BLUE EARTH-FARIBAULT-FREEBORN-MARTIN-STEELE-WASECA-WATONWAN. WINTER WEATHER ADVISORY UNTIL 11 AM CST THIS MORNING FOR BROWN- NICOLLET-REDWOOD. WI...WINTER STORM WARNING UNTIL MIDNIGHT CST TONIGHT FOR BARRON- CHIPPEWA-DUNN-EAU CLAIRE-PEPIN-PIERCE-POLK-RUSK-ST. CROIX. && $$ 99/99
AREA FORECAST DISCUSSION
NWS BLACKSBURG VA
1025 AM EST SUN DEC 9 2012 .SYNOPSIS... A COLD FRONT FROM NEW ENGLAND TO THE TENNESSEE VALLEY WILL MOVE SLOWLY SOUTHEAST TODAY BEFORE STALLING AND PUSHING BACK NORTH AS WARM FRONT TONIGHT. A MUCH STRONGER COLD FRONT WILL CROSS THROUGH THE AREA FROM THE WEST MONDAY EVENING. COOL HIGH PRESSURE WILL BUILD IN BEHIND THE FRONT FOR TUESDAY INTO FRIDAY. && .NEAR TERM /THROUGH TONIGHT/... AS OF 1015 AM EST SUNDAY... LATEST SURFACE OBSERVATIONS INDICATE THE COLD FRONT IS SITUATED JUST NORTHWEST OF OUR AREA THIS MORNING...STRETCHING THROUGH THE CENTRAL PORTIONS OF KENTUCKY AND WEST VIRGINIA INTO NORTHERN VIRGINIA. THE IMMEDIATE CONCERN IS A BAND OF SHOWER ACTIVITY MAKING ITS WAY ACROSS KENTUCKY...RIDING ALONG THE FRONT. EXPECT THESE SHOWERS TO SKIRT OUR MOUNTAIN EMPIRE COUNTIES BEGINNING AROUND NOON...AND CONTINUE MOVING NORTHEAST ACROSS THE ALLEGHANY HIGHLANDS THROUGH THE AFTERNOON BEFORE MOVING AWAY. SMALLER...MORE SUBTLE DISTURBANCES PASSING ACROSS THE AREA WILL TRIGGER SPOTTIER...LESS ORGANIZED SHOWER ACTIVITY ELSEWHERE THROUGH THE DAY AS WELL. AS THE DISTURBANCE TRIGGERING THESE SHOWERS MOVES NORTH...IT WILL HELP PUSH THE COLD FRONT SOUTH INTO THE FOOTHILLS. OUR LOCAL WRF AND RAP FORECAST MODELS INDICATED THE WEDGE REACHING THE ROANOKE RIVER BY THE END OF THE DAY...BEFORE ADVANCING SLOWLY BACK NORTH TONIGHT AS A WARM FRONT. HAVE MORE CLOUD COVER AND COOLER TEMPERATURES NORTH OF THE FRONT TODAY AND MORE FOG OVERNIGHT TONIGHT. USED A NON DIURNAL TREND FOR HOURLY TEMPERATURES OVERNIGHT. THOSE LOCATIONS THAT PULL OUT OF THE WEDGE WILL LIKELY WARM UP AS THEY GET BACK INTO THE WARM SECTOR. && .SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/... AS OF 330 AM EST SUNDAY... PRIMARY FOCUS FOR THE SHORT TERM FORECAST WAS ON THE TIMING OF THE COLD FRONT MOVING THROUGH THE FORECAST AREA LATE MONDAY AND MONDAY NIGHT. WITH SFC WAVES RIDING UP THE SFC BOUNDARY AND INITIAL UPPER LEVEL SHORTWAVE LIFTING NORTH WITH MORE ENERGY DIGGING INTO THE BASE OF THE UPPER LEVEL TROF IN THE CENTRAL U.S....CONTINUED TO LEAN TOWARD THE SLOWER MODEL SOLUTIONS. FOR THIS FORECAST PACKAGE...THE SLOWER NAM AND SREF WERE PREFERRED. AS WINDS VEER IN RESPONSE TO THE APPROACH OF THE UPPER LEVEL TROF...SFC WEDGE SHOULD HAVE ERODED BY 12Z MONDAY...OR SHORTLY THEREAFTER...LEAVING THE ENTIRE FORECAST FIRMLY ENTRENCHED IN THE WARM SECTOR. A DEEP SOUTHWEST FLOW ALONG WITH SOME BREAKS IN THE CLOUDS IN THE EAST SHOULD ALLOW TEMPS TO SOAR WELL ABOVE NORMAL...BUT STILL BELOW RECORDS FOR 12/10. BEST 850-300MB OMEGA PER THE NAM ARRIVES IN THE WEST AROUND 18Z MONDAY...BUT LIFTS TO THE NORTH AFTERWARDS WITH UPPER LEVEL SHORTWAVE. THIS LEAVES UNCERTAINTY ON HOW FAR EAST PRECIPITATION SHIELD CAN TRAVEL. AS A RESULT...KEPT MUCH HIGHER POPS IN THE MOUNTAINS...WITH HIGH CHANCE POPS IN THE EAST LATE MONDAY AND MONDAY NIGHT. NAM FORECAST SOUNDINGS INDICATE THE LOWER LEVEL OF THE ATMOSPHERE BEGINS DRYING WHEN TEMPS COLD ENOUGH FOR SNOW BEGINS TO ARRIVE ALONG THE WESTERN SLOPES. MAY STILL BE ABLE TO SQUEEZE OUT SOME LIGHT SNOW SHOWERS IN THE HIGHEST ELEVATIONS OF SOUTHEAST WV/ALLEGHANY HIGHS FOR A FEW HOURS TUESDAY MORNING. EVEN THE SLOWEST SREF KEEPS SFC BOUNDARY WELL SOUTHEAST OF THE FORECAST AREA ON TUESDAY. WEAK SFC WAVES MOVING THROUGH EASTERN NC/VA ON TUESDAY WILL KEEP SOME CLOUDS IN THE FAR EAST...BUT LOW LEVEL NORTHWEST WINDS WILL KEEP THE FORECAST AREA DRY BY 18Z. AS SFC RIDGE QUICKLY BUILDS OVER THE AREA TUESDAY...COLD AIR ADVECTION DIMINISHES DURING THE DAY AND EXPECT TEMPS TO RECOVER AND USED A BLEND OF THE NAM/GFS MOS GUIDANCE FOR HIGHS. && .LONG TERM /WEDNESDAY THROUGH SATURDAY/... AS OF 330 PM EST SATURDAY... HIGH PRESSURE WILL CONTROL THE WEATHER PATTERN THROUGH FRIDAY. WILL BE KEEPING AN EYE ON A LOW PRESSURE SYSTEM DEVELOPING ALONG THE CAROLINA COAST OF WEDNESDAY/THURSDAY TO SEE IF ANY SHOWER ACTIVITY ADVANCES INTO THE PIEDMONTS...BUT BECOMING MORE CONFIDENT THAT THIS ACTIVITY WILL STAY EAST OF THE AREA. THE NEXT BIG STORM SYSTEM TO WATCH WILL ARRIVE NEXT WEEKEND AS A DEEP LOW PRESSURE SYSTEM PASSES EASTWARD FROM THE CENTRAL PLAINS INTO THE GREAT LAKES...DRAGGING A COLD FRONT TOWARD OUR AREA. && .AVIATION /15Z SUNDAY THROUGH THURSDAY/... AS OF 705 AM EST SUNDAY... SCATTERED SHOWERS WILL MOVE NORTHEAST AWAY FROM KLWB BY 14Z/9AM THIS MORNING. COVERAGE OF IFR TO LIFR CEILINGS IS VARIABLE THIS MORNING. MODERATE CONFIDENCE THAT ANY LOW STRATUS WILL LIFT TO AT LEAST MVFR LEVELS BY 18Z/1PM. COLD FRONT WAS OVER NORTHERN VIRGINIA. EXPECT BOUNDARY TO DROP SOUTH THROUGH THE FOOTHILLS TODAY. IFR TO LIFR CLOUDS NORTH OF THE FRONT TONIGHT AT LYH AND POSSIBLE ROA. EXPECT MVFR FOG MOST LOCATIONS AGAIN TONIGHT. DEPENDS ON HOW FAR WEDGE ADVANCES BUT EVEN KROA MAY HAVE MVFR FOG. CHANCE OF SHOWERS WILL CONTINUE TODAY WITH MORE WIDESPREAD PRECIPITATION MOVING INTO THE MOUNTAINS BY MONDAY MORNING. FRONT LIFTS BACK NORTH EARLY MONDAY THEN VERY STRONG COLD FRONT PUSHES THROUGH FROM THE WEST MONDAY EVENING. HAVE ADDED LOW LEVEL WINDS SHEAR TO THE TAFS TONIGHT DUE TO INCREASING LOW LEVEL JET. MODELS HAVE WINDS JUST ABOVE THE SURFACE FROM THE SOUTHWEST AT 30 TO 40 KNOTS. EXPECT GUSTY NORTHWEST WINDS BEHIND THE FRONT ON MONDAY NIGHT AND TUESDAY. CONDITIONS WILL IMPROVE ON TUESDAY EVENING AS HIGH PRESSURE BEGINS TO SETTLE ACROSS THE AREA. LINGERING MOISTURE IN THE MOUNTAINS TUESDAY WILL RESULT IN MVFR CONDITIONS AND THE POSSIBILITY OF SNOW SHOWERS AS COLDER AIR SURGES INTO THE AREA. VFR WILL RETURN FOR TUESDAY NIGHT THROUGH FRIDAY. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...NONE. NC...NONE. WV...NONE. && $$ SYNOPSIS...AMS NEAR TERM...AMS/NF SHORT TERM...PH LONG TERM...NF AVIATION...AMS
AREA FORECAST DISCUSSION
NWS BLACKSBURG VA
714 AM EST SUN DEC 9 2012 .SYNOPSIS... A COLD FRONT FROM NEW ENGLAND TO THE TENNESSEE VALLEY WILL MOVE SLOWLY SOUTHEAST TODAY BEFORE STALLING AND PUSHING BACK NORTH AS WARM FRONT TONIGHT. A MUCH STRONGER COLD FRONT WILL CROSS THROUGH THE AREA FROM THE WEST MONDAY EVENING. COOL HIGH PRESSURE WILL BUILD IN BEHIND THE FRONT FOR TUESDAY INTO FRIDAY. && .NEAR TERM /THROUGH TONIGHT/... AS OF 430 AM EST SATURDAY... SCATTERED TO NUMEROUS SHOWERS...ASSOCIATED WITH A SHORT WAVE MOVING THROUGH WEST VIRGINIA...WERE TRACKING NORTHEAST ACROSS THE WESTERN COUNTY WARNING AREA EARLY THIS MORNING. WATER VAPOR LOOP SHOWED ANOTHER SHORT WAVE JUST ENTERING WESTERN KENTUCKY AND TENNESSEE WHICH MODELS TAKE ALONG THE SAME TRACK. THIS SHOULD BRING MORE SHOWERS TO THE WESTERN COUNTY WARNING AREA THIS AFTERNOON. SCATTERED SHOWERS WERE ALSO MOVING THROUGH SOUTHSIDE VIRGINIA. ONCE THESE SHOWERS MOVE THROUGH THIS MORNING THE CHANCE OF PRECIPITATION WILL BE LOWER IN THIS PART OF THE FORECAST AREA FOR THE REST OF THE DAY. THE COLD FRONT EXTENDED FRONT NEW JERSEY TO CENTRAL KENTUCKY. ONCE THE WEST VIRGINIA SHORT WAVE MOVES SLIGHTLY FARTHER NORTH...THE FRONT WILL ADVANCE SOUTH INTO THE FOOTHILLS THIS MORNING. LOCAL WRK AND LATEST RAP SHOWED THE WEDGE REACHING THE ROANOKE RIVER BY THE END OF THE DAY BEFORE ADVANCING SLOWLY BACK NORTH TONIGHT. HAVE MORE CLOUD COVER AND COOLER TEMPERATURES NORTH OF THE FRONT TODAY AND MORE FOG OVERNIGHT TONIGHT. USED A NON DIURNAL TREND FOR HOURLY TEMPERATURES OVERNIGHT. THOSE LOCATIONS THAT PULL OUT OF THE WEDGE WILL LIKELY WARM UP AS THEY GET BACK INTO THE WARM SECTOR. && .SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/... AS OF 330 AM EST SUNDAY... PRIMARY FOCUS FOR THE SHORT TERM FORECAST WAS ON THE TIMING OF THE COLD FRONT MOVING THROUGH THE FORECAST AREA LATE MONDAY AND MONDAY NIGHT. WITH SFC WAVES RIDING UP THE SFC BOUNDARY AND INITIAL UPPER LEVEL SHORTWAVE LIFTING NORTH WITH MORE ENERGY DIGGING INTO THE BASE OF THE UPPER LEVEL TROF IN THE CENTRAL U.S....CONTINUED TO LEAN TOWARD THE SLOWER MODEL SOLUTIONS. FOR THIS FORECAST PACKAGE...THE SLOWER NAM AND SREF WERE PREFERRED. AS WINDS VEER IN RESPONSE TO THE APPROACH OF THE UPPER LEVEL TROF...SFC WEDGE SHOULD HAVE ERODED BY 12Z MONDAY...OR SHORTLY THEREAFTER...LEAVING THE ENTIRE FORECAST FIRMLY ENTRENCHED IN THE WARM SECTOR. A DEEP SOUTHWEST FLOW ALONG WITH SOME BREAKS IN THE CLOUDS IN THE EAST SHOULD ALLOW TEMPS TO SOAR WELL ABOVE NORMAL...BUT STILL BELOW RECORDS FOR 12/10. BEST 850-300MB OMEGA PER THE NAM ARRIVES IN THE WEST AROUND 18Z MONDAY...BUT LIFTS TO THE NORTH AFTERWARDS WITH UPPER LEVEL SHORTWAVE. THIS LEAVES UNCERTAINTY ON HOW FAR EAST PRECIPITATION SHIELD CAN TRAVEL. AS A RESULT...KEPT MUCH HIGHER POPS IN THE MOUNTAINS...WITH HIGH CHANCE POPS IN THE EAST LATE MONDAY AND MONDAY NIGHT. NAM FORECAST SOUNDINGS INDICATE THE LOWER LEVEL OF THE ATMOSPHERE BEGINS DRYING WHEN TEMPS COLD ENOUGH FOR SNOW BEGINS TO ARRIVE ALONG THE WESTERN SLOPES. MAY STILL BE ABLE TO SQUEEZE OUT SOME LIGHT SNOW SHOWERS IN THE HIGHEST ELEVATIONS OF SOUTHEAST WV/ALLEGHANY HIGHS FOR A FEW HOURS TUESDAY MORNING. EVEN THE SLOWEST SREF KEEPS SFC BOUNDARY WELL SOUTHEAST OF THE FORECAST AREA ON TUESDAY. WEAK SFC WAVES MOVING THROUGH EASTERN NC/VA ON TUESDAY WILL KEEP SOME CLOUDS IN THE FAR EAST...BUT LOW LEVEL NORTHWEST WINDS WILL KEEP THE FORECAST AREA DRY BY 18Z. AS SFC RIDGE QUICKLY BUILDS OVER THE AREA TUESDAY...COLD AIR ADVECTION DIMINISHES DURING THE DAY AND EXPECT TEMPS TO RECOVER AND USED A BLEND OF THE NAM/GFS MOS GUIDANCE FOR HIGHS. && .LONG TERM /WEDNESDAY THROUGH SATURDAY/... AS OF 330 PM EST SATURDAY... HIGH PRESSURE WILL CONTROL THE WEATHER PATTERN THROUGH FRIDAY. WILL BE KEEPING AN EYE ON A LOW PRESSURE SYSTEM DEVELOPING ALONG THE CAROLINA COAST OF WEDNESDAY/THURSDAY TO SEE IF ANY SHOWER ACTIVITY ADVANCES INTO THE PIEDMONTS...BUT BECOMING MORE CONFIDENT THAT THIS ACTIVITY WILL STAY EAST OF THE AREA. THE NEXT BIG STORM SYSTEM TO WATCH WILL ARRIVE NEXT WEEKEND AS A DEEP LOW PRESSURE SYSTEM PASSES EASTWARD FROM THE CENTRAL PLAINS INTO THE GREAT LAKES...DRAGGING A COLD FRONT TOWARD OUR AREA. && .AVIATION /12Z SUNDAY THROUGH THURSDAY/... AS OF 705 AM EST SUNDAY... SCATTERED SHOWERS WILL MOVE NORTHEAST AWAY FROM KLWB BY 14Z/9AM THIS MORNING. COVERAGE OF IFR TO LIFR CEILINGS IS VARIABLE THIS MORNING. MODERATE CONFIDENCE THAT ANY LOW STRATUS WILL LIFT TO AT LEAST MVFR LEVELS BY 18Z/1PM. COLD FRONT WAS OVER NORTHERN VIRGINIA. EXPECT BOUNDARY TO DROP SOUTH THROUGH THE FOOTHILLS TODAY. IFR TO LIFR CLOUDS NORTH OF THE FRONT TONIGHT AT LYH AND POSSIBLE ROA. EXPECT MVFR FOG MOST LOCATIONS AGAIN TONIGHT. DEPENDS ON HOW FAR WEDGE ADVANCES BUT EVEN KROA MAY HAVE MVFR FOG. CHANCE OF SHOWERS WILL CONTINUE TODAY WITH MORE WIDESPREAD PRECIPITATION MOVING INTO THE MOUNTAINS BY MONDAY MORNING. FRONT LIFTS BACK NORTH EARLY MONDAY THEN VERY STRONG COLD FRONT PUSHES THROUGH FROM THE WEST MONDAY EVENING. HAVE ADDED LOW LEVEL WINDS SHEAR TO THE TAFS TONIGHT DUE TO INCREASING LOW LEVEL JET. MODELS HAVE WINDS JUST ABOVE THE SURFACE FROM THE SOUTHWEST AT 30 TO 40 KNOTS. EXPECT GUSTY NORTHWEST WINDS BEHIND THE FRONT ON MONDAY NIGHT AND TUESDAY. CONDITIONS WILL IMPROVE ON TUESDAY EVENING AS HIGH PRESSURE BEGINS TO SETTLE ACROSS THE AREA. LINGERING MOISTURE IN THE MOUNTAINS TUESDAY WILL RESULT IN MVFR CONDITIONS AND THE POSSIBILITY OF SNOW SHOWERS AS COLDER AIR SURGES INTO THE AREA. VFR WILL RETURN FOR TUESDAY NIGHT THROUGH FRIDAY. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...NONE. NC...NONE. WV...NONE. && $$ SYNOPSIS...AMS NEAR TERM...AMS SHORT TERM...PH LONG TERM...NF AVIATION...AMS
AREA FORECAST DISCUSSION
NWS LINCOLN IL
225 PM CST SUN DEC 9 2012 .DISCUSSION... ISSUED 210 PM CST SUN DEC 9 2012 SHORT TERM...TONIGHT THROUGH WEDNESDAY NIGHT COVERAGE OF RAIN ACROSS THE FORECAST AREA EARLY TONIGHT ALONG WITH TEMPERATURES THE FIRST HALF OF THE UPCOMING WEEK...ARE THE MAIN FORECAST CONCERNS. USING MORE OF THE NAM-WRF THIS FORECAST PERIOD ALTHOUGH MODEL DIFFERENCES WERE NEGLIGIBLE. COLD FRONT IS FORECAST TO PUSH ACROSS THE REGION TONIGHT PUTTING AN END TO THE RAIN AND BRINGING IN MUCH COLDER WEATHER FOR THE FIRST HALF OF THE WORK WEEK. THE SNOW ASSOCIATED WITH THE STORM SYSTEM WILL REMAIN TO OUR NORTH WHILE A SECONDARY BAND OF SHOWERS AND ISOLATED THUNDERSTORMS WILL ACCOMPANY THE COLD FRONT ACROSS EAST CENTRAL THRU SOUTHEAST ILLINOIS. THE THUNDER THREAT LOOKS TO BE QUITE EARLY THIS EVE AND CONFINED ALONG AND SOUTH OF THE I-70 CORRIDOR CLOSER TO THE DEEPER MOISTURE AND BETTER INSTABILITY. FURTHER TO THE NORTH...FORECAST SOUNDINGS CONTINUE TO INDICATE NOT MUCH IF ANY ICE PRESENT IN THE UPPER LEVELS OF THE CLOUD...AND IF THERE WAS ANY...THE LEVELS JUST BELOW IT WERE TOO DRY TO SUPPORT ANY SNOW THIS EVENING AS THE COLD AIR SWEEPS IN. ON MONDAY...WITH STRONG CYCLONIC FLOW/LOW LEVEL COLD ADVECTION INDICATED...ALONG WITH MODELS DEPICTING THE 850 MB THERMAL TROF PUSHING THRU THE AREA DURING THE LATE MORNING AND EARLY AFTN HOURS...WE SHOULD SEE PLENTY OF CLOUD COVER AND GUSTY NORTHWEST WINDS...ALONG WITH SOME FLURRIES...ESP ACRS THE NORTH AND EAST. THE NAM-WRF AND GFS INDICATES A 500 MB VORT TROF TO SHIFT THRU THE AREA AS WELL DURING THE AFTN ACCOMPANIED BY SOME COLD TEMPS ALOFT. FORECAST SOUNDINGS SHOWING SOME DECENT LOW AND MID LEVEL LAPSE RATES ALONG WITH MORE MOISTURE ABOVE 850 MB THAN PREVIOUS MODELS FORECAST SO WILL HAVE AT LEAST A CHANCE FOR FLURRIES MAINLY ACRS THE NORTH AND EAST DURING THE DAY. 500 MB TROF AXIS SHOULD EXIT TO OUR EAST LATE MONDAY AFTERNOON TAKING ANY FLURRY THREAT WITH IT. WE SHOULD THEN SEE A DECREASE IN CLOUDS AND WINDS DURING THE EVENING WITH THE NAM SHOWING THE SURFACE RIDGE AXIS RIGHT OVER THE FORECAST AREA BY 12Z TUESDAY. AFTER A COLD START TUESDAY MORNING WE SHOULD SEE A RATHER QUIET WEATHER PATTERN OVER THE MIDWEST THRU WEDNESDAY NIGHT AS UPPER LEVEL HEIGHTS BUILD OVER THE CENTER OF THE NATION AS A DEEP TROF DIGS INTO THE ROCKIES. LONG TERM...THURSDAY THROUGH SUNDAY THE UPPER FLOW ACROSS THE MIDWEST BECOMES SOUTHWESTERLY AS THE AFOREMENTIONED TROF SETS UP OVER THE ROCKIES LATE IN THE WEEK. THIS SHOULD BRING WARMER TEMPERATURES INTO OUR AREA WITH DRY CONDITIONS HOLDING THRU FRIDAY. THE LATEST OPERATIONAL GFS HAS MADE A SIGNIFICANT CHANGE FROM ITS PREVIOUS RUNS WITH RESPECT TO THE LATE FRIDAY/SATURDAY WEATHER SYSTEM IN TAKING TWO SEPARATE SYSTEMS ACROSS THE MIDWEST RATHER THAN ONE LARGE LOW AT THE SURFACE AND AT 500 MB...WHICH THE 12Z ECMWF CONTINUES TO INDICATE. WILL CONTINUE TO SIDE WITH THE MORE CONSISTENT ECMWF SOLUTION IN BRINGING RAIN CHANCES INTO OUR AREA FRIDAY NIGHT AND CONTINUING AT LEAST A CHANCE OF RAIN ON SATURDAY. THE ECMWF HAS TRENDED A BIT SLOWER WITH ITS TRACK ACRS THE MIDWEST ON SATURDAY SO WILL KEEP AT LEAST SLIGHT CHANCES GOING INTO SATURDAY EVENING OVER THE EASTERN TWO-THIRDS OF THE FORECAST AREA. ACTIVE PATTERN SHOULD HOLD AFTER OUR WEEKEND SYSTEM MOVES OUT AS ANOTHER STRONG UPPER WAVE IS FORECAST TO GET EJECTED ENE OUT OF THE MEAN LONGWAVE TROF POSITION OVER THE ROCKIES. THIS SHOULD BRING ANOTHER STORM SYSTEM NORTHEAST INTO THE MIDWEST...ALTHOUGH THE LATEST ECMWF IS INDICATING THE STRONGEST CORE OF WINDS AT 250 MB STILL ON THE WEST SIDE OF THE TROF LATE NEXT WEEKEND...SUGGESTING THIS WAVE MAY DIG MORE THAN ITS PREDECESSOR AND TAKE A MORE SOUTHERLY TRACK. ANY WEATHER ASSOCIATED WITH THIS SHORTWAVE WILL OCCUR BEYOND THIS FORECAST PERIOD. WITH THE UPPER FLOW FORECAST TO REMAIN SOUTHWEST THRU NEXT WEEKEND... NO SIGNS OF ANY SIGNIFICANT BUCKLING OF THE JET TO ALLOW A PROLONGED PERIOD OF COLD INTO THE MIDWEST...OTHER THAN THE BRIEF COOL OFFS BEHIND THESE SOUTHWEST SYSTEMS. SMITH && .AVIATION... ISSUED 1059 AM CST SUN DEC 9 2012 CEILINGS REMAIN THE PRIMARY CONCERN FOR THIS TAF SET. CENTRAL ILLINOIS TAF SITES CURRENTLY AROUND 300-400 FEET...WITH VISIBILITY OF 1 TO 2SM. SOME MODEST IMPROVEMENTS EXPECTED AFTER A FRONTAL BOUNDARY CURRENTLY IN EASTERN MISSOURI PUSHES THROUGH OUR AREA... GENERALLY CROSSING THE TAF SITES IN THE 19-22Z TIME FRAME. VISIBLE SATELLITE IMAGERY SHOWING A CLEARING LINE EXTENDING NORTH AND SOUTHWEST FROM KANSAS CITY. AWIPS TIME-OF-ARRIVAL TOOL WOULD PLACE IT AROUND KPIA/KSPI TOWARD 23Z IF IT HOLDS TOGETHER...HOWEVER THE LOW LEVEL HUMIDITY PLOTS OFF THE RAP AND NAM MODELS SUGGEST ONLY SOME TEMPORARY BREAKS IN THE CEILING BY THAT POINT...SO WILL MAINTAIN MVFR CEILINGS FOR NOW. CIRCULATION AROUND THE DEPARTING STORM SYSTEM EXPECTED TO BRING ANOTHER SLUG OF STRATOCUMULUS OVERNIGHT...PERSISTING MUCH OF THE MORNING...WITH CEILINGS REMAINING BELOW 3000 FEET THROUGH MONDAY MORNING. GEELHART && .ILX WATCHES/WARNINGS/ADVISORIES... NONE. && $$
AREA FORECAST DISCUSSION
NWS LINCOLN IL
1115 AM CST SUN DEC 9 2012 .DISCUSSION... ISSUED 1000 AM CST SUN DEC 9 2012 FIRST WAVE OF PRECIPITATION HAS LARGELY LIFTED OUT OF THE FORECAST AREA...WITH SOME RESIDUAL SHOWERS/DRIZZLE LINGERING...ESPECIALLY ACROSS THE NORTH. SHOWERS AND SCATTERED THUNDERSTORMS ACROSS SOUTHERN MISSOURI EXPECTED TO FOLLOW A WAVE OF ENERGY LIFTING NORTHEAST OUT OF NORTHERN ARKANSAS...AND WILL POSE A THREAT TO AREAS SOUTH OF I-70 BY EARLY AFTERNOON. THE REMAINDER OF THE FORECAST AREA WILL ONLY SEE SCATTERED SHOWERS DURING THE AFTERNOON HOURS. HAVE UPDATED THE ZONES/GRIDS FOR THE LATEST RAIN TRENDS. TEMPERATURES WERE LARGELY IN GOOD SHAPE AND NEEDED LITTLE MODIFICATION. GEELHART && .AVIATION... ISSUED 1059 AM CST SUN DEC 9 2012 CEILINGS REMAIN THE PRIMARY CONCERN FOR THIS TAF SET. CENTRAL ILLINOIS TAF SITES CURRENTLY AROUND 300-400 FEET...WITH VISIBILITY OF 1 TO 2SM. SOME MODEST IMPROVEMENTS EXPECTED AFTER A FRONTAL BOUNDARY CURRENTLY IN EASTERN MISSOURI PUSHES THROUGH OUR AREA... GENERALLY CROSSING THE TAF SITES IN THE 19-22Z TIME FRAME. VISIBLE SATELLITE IMAGERY SHOWING A CLEARING LINE EXTENDING NORTH AND SOUTHWEST FROM KANSAS CITY. AWIPS TIME-OF-ARRIVAL TOOL WOULD PLACE IT AROUND KPIA/KSPI TOWARD 23Z IF IT HOLDS TOGETHER...HOWEVER THE LOW LEVEL HUMIDITY PLOTS OFF THE RAP AND NAM MODELS SUGGEST ONLY SOME TEMPORARY BREAKS IN THE CEILING BY THAT POINT...SO WILL MAINTAIN MVFR CEILINGS FOR NOW. CIRCULATION AROUND THE DEPARTING STORM SYSTEM EXPECTED TO BRING ANOTHER SLUG OF STRATOCUMULUS OVERNIGHT...PERSISTING MUCH OF THE MORNING...WITH CEILINGS REMAINING BELOW 3000 FEET THROUGH MONDAY MORNING. GEELHART && .PREV DISCUSSION... ISSUED 245 AM CST SUN DEC 9 2012 SHORT TERM...TODAY THROUGH TUESDAY LOW PRESSURE CURRENTLY OVER OKLAHOMA WILL TRACK NORTHEASTWARD TODAY...EVENTUALLY REACHING CENTRAL INDIANA BY EARLY EVENING. THIS PARTICULAR TRACK WILL KEEP MUCH OF THE KILX CWA ON THE COOL SIDE OF THE SYSTEM...WHILE AREAS ALONG/SOUTH OF THE I-70 CORRIDOR PUNCH INTO THE WARM SECTOR DURING THE AFTERNOON. ISENTROPIC UPGLIDE NOTED ON THE 295K SURFACE WILL BECOME NEUTRAL AS THE WEAK LOW PRESSURE CENTER MOVES INTO THE VICINITY TOWARD MIDDAY. AS A RESULT...THINK SHOWERS WILL BE MOST WIDESPREAD THROUGH 15Z/9AM...BEFORE MAIN PRECIP AREA SHIFTS FURTHER NORTHEAST. WILL THEREFORE CARRY CATEGORICAL POPS THIS MORNING...THEN JUST CHANCE POPS ACROSS MUCH OF THE AREA THIS AFTERNOON. THE EXCEPTION WILL BE ALONG/SOUTH OF I-70...WHERE MODELS TRY TO DEVELOP ADDITIONAL SHOWERS IN THE WARM SECTOR LATER IN THE DAY. MAY EVEN BE A FEW ISOLATED THUNDERSTORMS ACROSS THE FAR SE CWA...COURTESY OF DEWPOINTS IN THE LOWER 50S AND LIFTED INDEX VALUES APPROACHING 0C. HIGH TEMPERATURES WILL BE QUITE VARIABLE TODAY...RANGING FROM THE MIDDLE 40S IN THE ILLINOIS RIVER VALLEY...TO THE LOWER 60S SOUTH OF I-70. AS LOW TRACKS INTO CENTRAL INDIANA...WINDS WILL SWITCH TO THE NORTHWEST...ALLOWING A MUCH COLDER AIR MASS TO FILTER INTO THE AREA TONIGHT. 00Z DEC 9 MODELS ARE NOW INDICATING THAT THE COLD AIR WILL LAG BEHIND THE DEPARTING MOISTURE JUST ENOUGH TO PREVENT ANY CHANGE OVER FROM LIGHT RAIN SHOWERS TO SNOW SHOWERS. WILL LINGER A FEW RAIN SHOWERS THROUGH THE EVENING EAST OF I-55...THEN WILL GO MAINLY DRY OVERNIGHT. LOW TEMPERATURES WILL RANGE FROM THE LOWER 20S AROUND GALESBURG...TO THE MIDDLE 30S NEAR LAWRENCEVILLE. BELOW NORMAL TEMPS WILL TAKE HOLD ACROSS THE MIDWEST FOR MONDAY AND TUESDAY...AS CANADIAN HIGH PRESSURE DOMINATES THE WEATHER. HIGHS BOTH DAY WILL REMAIN IN THE 30S...WHILE LOWS DIP INTO THE TEENS MONDAY NIGHT. LONG TERM...WEDNESDAY THROUGH SATURDAY UPPER TROUGHING WILL RELAX BY MID-WEEK...FOLLOWED BY A RETURN TO ZONAL FLOW. END RESULT WILL BE MODERATING TEMPERATURES THROUGH THE BALANCE OF THE WEEK...WITH HIGHS CLIMBING INTO THE UPPER 40S AND LOWER 50S BY FRIDAY AND SATURDAY. BOTH THE ECMWF AND GFS MAINTAIN DRY CONDITIONS THROUGH FRIDAY...BUT THEN BRING NEXT SIGNIFICANT SHORT-WAVE INTO THE REGION OVER THE WEEKEND. GIVEN GOOD MODEL AGREEMENT...WILL CARRY HIGH CHANCE POPS FOR RAIN FRIDAY NIGHT INTO SATURDAY. BARNES && .ILX WATCHES/WARNINGS/ADVISORIES... NONE. && $$
AREA FORECAST DISCUSSION
NWS TOPEKA KS
310 PM CST SUN DEC 9 2012 .DISCUSSION... 20Z WATER VAPOR IMAGERY SHOWS AN UPPER LEVEL TROUGH FROM THE FOUR CORNERS REGION INTO THE DAKOTAS. ONE SHORTWAVE WAS LIFTING NORTHEAST INTO MN WITH ANOTHER SHORTWAVE OVER THE CO AND NM ROCKIES. AT THE SURFACE...A VERY STRONG COLD FRONT HAS PUSHED SOUTH INTO NORTH TX AND EAST INTO CENTRAL MO. AREA OBSERVATIONS INDICATE STRONG COLD AND DRY AIR ADVECTION IS ONGOING. RADAR TRENDS THROUGHOUT THE DAY HAVE SUPPORTED THE IDEA THAT THE DRY AIR NEAR THE SURFACE IS TO MUCH FOR WEAK FRONTOGENESIS IN THE MID LEVELS TO OVERCOME. FOR TONIGHT AND MONDAY...MODELS SHOW LITTLE OR NO LARGE SCALE FORCING THROUGH THE PERIOD WITH THE ONLY INDICATION OF FORCING FOR PRECIP BEING WEAK MID LEVEL FRONTOGENESIS THROUGH THE EARLY EVENING. GIVEN THE CONTINUED ADVECTION OF DRY AIR IN THE LOWER TROPOSPHERE... THINK PRECIP CHANCES ARE PRETTY CLOSE TO NIL. BY MONDAY...THE COLD SURFACE RIDGE OF HIGH PRESSURE WITH VERY DRY AIR IS EXPECTED TO DOMINATE THE WEATHER AS THE SHORTWAVE OVER THE SOUTHERN ROCKIES PASSES MAINLY TO THE SOUTH OF THE FORECAST AREA. THEREFORE THE FORECAST WILL REMAIN DRY. ABOUT THE ONLY WEATHER CONCERN IS CLOUD COVER OVERNIGHT. VISIBLE SATELLITE SHOWS AN AREA OF STRATOCU MOVING SWIFTLY SOUTH ACROSS EASTERN NEB. THE RAP SHOWS THIS DECK OF LOW CLOUDS HANGING IN ACROSS NORTHEAST AND EAST CENTRAL KS THROUGH MUCH OF THE NIGHT...AND THE NAM AND GFS TO A LESSER EXTENT SUPPORT THE IDEA. SO THINK SKIES WILL BE MOSTLY CLOUDY TONIGHT. BECAUSE OF THIS HAVE KEPT LOWS A DEGREE OR TWO WARMER THAN THE MOS GUIDANCE ACROSS EASTERN KS. ADDITIONALLY A STRONGLY MIXED BOUNDARY LAYER SHOULD HELP KEEP LOWS FROM PLUMMETING. NORTH CENTRAL KS COULD SEE SINGLE DIGIT LOWS WHERE SKIES SHOULD CLEAR OUT SOONER. WITH SUCH A COLD START TO THE DAY...HIGHS ARE EXPECTED TO ONLY MAKE IT INTO THE LOWER AND MID 30S FOR MONDAY EVEN WITH MOSTLY SUNNY SKIES. WOLTERS MID WEEK PERIODS LOOKING RATHER BENIGN. SOME MID AND HIGH CLOUDS SHOULD BE ALL THAT RESULTS FROM THE NEXT UPPER WAVE PASSING THROUGH THE CENTRAL PLAINS MONDAY NIGHT INTO EARLY TUESDAY. LOW LEVEL FLOW REMAINS MAINLY WESTERLY TUESDAY FOR WEAK WARM AIR ADVECTION...AND WAA INCREASES INTO WEDNESDAY AND THURSDAY AS BROAD RIDGING OVERTAKES THE CENTRAL AND EASTERN CONUS. THE DEGREE OF MIXING INTO THE WARM AND DRY MID LEVELS IS THE MAIN QUESTION FOR HOW WARM HIGHS WILL GET. BUMPED THEM UP A FEW DEGREES AT THIS POINT BUT FURTHER INCREASES MAY BE NEEDED. SSW WINDS INCREASE FOR WEDNESDAY INTO THURSDAY AND RELATIVE HUMIDITIES MAY DROP TO LEVELS OF SOME CONCERN FOR FIRE WEATHER MAINLY ON WEDNESDAY. MEDIUM RANGE MODELS ARE IN DECENT AGREEMENT WITH WESTERN TROF AND UPPER LOW IN THE SOUTHWEST CONUS ON THURSDAY...BUT DIFFERENCES MAGNIFY QUICKLY INTO THE WEEKEND. THE 12Z ECMWF PUSHES THE LOW EAST AHEAD OF THE NORTHERN TROF AND ALLOWS A LOW TO RE-CLOSE AND DEEPEN RAPIDLY OVER THE CENTRAL PLAINS...WHILE THE 12Z GFS KEEPS THE SOUTHERN LOW BEHIND THE NORTHERN TROF FOR A WEAKENING WAVE IN THE PLAINS. MODERATE PRECIPITATION CHANCES REMAIN...CENTERED AROUND FRIDAY NIGHT...WITH SOME OPPORTUNITY FOR CONVECTION IN THE MORE AMPLIFIED SOLUTIONS AND MINOR CONCERN FOR WINTRY PRECIP AS THE EVENT WINDS DOWN. TEMPS SHOULD RETURN TO NEAR MID-DECEMBER NORMALS FOR SUNDAY. 65 && .AVIATION... LATEST OBS AND RADAR SHOWING LOW LEVEL DRY AIR WINNING OUT OVER THE WEAK FORCING...AND MODELS SHOW THESE CONDITIONS PERSISTING THROUGH THE AFTERNOON. THERE IS ONE LITTLE PATCH OF STRATOCU SEEN ON SATELLITE NEAR TOP AND FOE WHICH WILL BE OUT SHORTLY. OTHERWISE VFR CONDITIONS SHOULD PREVAIL INTO THE EARLY EVENING. MODELS DO HINT AT SOME MVFR CIGS MOVING SOUTH THROUGH EASTERN NEB OVERNIGHT. THEREFORE HAVE CONTINUED THE PREV FORECAST OF CIGS BETWEEN 2 AND 3 KFT OVERNIGHT. WINDS WILL REMAIN UP DUE TO A STRONG PRESSURE GRADIENT. WOLTERS && .TOP WATCHES/WARNINGS/ADVISORIES... NONE. && $$
AREA FORECAST DISCUSSION
NWS WICHITA KS
1205 PM CST SUN DEC 9 2012 .UPDATE... FALLING TEMPERATURES ARE ANTICIPATED THROUGH THE AFTERNOON HOURS ACROSS MUCH OF CENTRAL AND SOUTHEAST KANSAS WITHIN STRONG LOW-LEVEL CAA POST- FRONTAL REGIME. WINDS MAY FLIRT WITH ADVISORY CRITERIA BRIEFLY...ESPECIALLY ACROSS CENTRAL KANSAS HOWEVER DUE TO THE SHORT DURATION NO HEADLINES ARE ANTICIPATED. VERY DRY IS ALSO BEING ADVECTED THROUGH THE PBL DECREASING THE PROBABILITY FOR SEEING ANY SNOW FLURRIES SO MAINTAINED A DRY FORECAST THROUGH THE OVERNIGHT PERIOD. MWM && .AVIATION...18Z TAFS KRSL/KSLN/KHUT/KICT/KCNU NORTHWEST WINDS AROUND 25 KNOTS WITH GUSTS INTO THE 30-35 KNOT RANGE ARE EXPECTED BEHIND A STRONG COLD FRONT. THE WINDS WILL LIKELY STAY UP INTO THE EVENING HOURS BEFORE DIMINISHING TOWARD MORNING. MID CLOUDS IN THE 7-10K FT RANGE WILL GRADUALLY CLEAR OVERNIGHT WITHIN A VERY DRY AND SUBSIDENT AIRMASS BUILDING INTO THE AREA. && .PREV DISCUSSION... /ISSUED 527 AM CST SUN DEC 9 2012/ AVIATION...12Z TAFS KRSL/KSLN/KHUT/KICT/KCNU THE MAIN AVIATION FORECAST CONCERN IS LIFR/IFR CONDITIONS AHEAD OF THE FRONT AND THEN STRONG GUSTY WINDS BEHIND THE FRONT TODAY. THE COLD FRONT IS THROUGH MUCH OF KANSAS...BUT THE STRONGER WINDS ARE JUST REACHING KRSL AS OF 11Z. WINDS WILL ONLY CONTINUE TO GET STRONGER THROUGHOUT THE DAY WITH 20-25 KTS GUSTING TO 30-35 EXPECTED ACROSS ALL TERMINALS TODAY. WINDS WILL DECREASE SOME...BUT STAY BREEZY OVERNIGHT. AHEAD OF THE FRONT LIFR AND IFR CONDITIONS DOMINATE UNDER LOW STRATUS. AS THE DRIER/COOLER AIR MOVES IN BEHIND THE FRONT...LOW STRATUS IS SCATTERING OUT WITH A MID LEVEL CLOUD DECK OVERHEAD. HAVE REMAINED PESSIMISTIC WITH THE FORECAST AT SITES THAT ARE AHEAD OF THE FRONT...KICT/KCNU KEEPING THEM IN LIFR UNTIL THE EXPECTED FRONTAL PASSAGE...ALTHOUGH IT MAY BE OFF AND ON WITH RAGGED CEILINGS ACROSS THE AREA. SKIES WILL BEGIN TO CLEAR OVERNIGHT FROM KRSL TO KICT UNDER HIGH PRESSURE. WHILE THERE IS STILL A HINT OF SOME PRECIPITATION WITH THIS SYSTEM...CONFIDENCE IS LOW THAT ANY WILL ACTUALLY REACH THE GROUND. THERE IS DECENT LIFT IN THE MID-LEVELS...BUT THE LOWEST 8-12 KFT ARE VERY DRY AND WOULD EXPECT ANY PRECIPITATION THAT DOES FALL TO EVAPORATE. THAT BEING SAID...CANNOT RULE OUT SOME DRIZZLE AHEAD OF THE FRONT...AND SOME FLURRIES BEHIND THE FRONT. DID LEAVE MENTION OF FLURRIES OUT OF THE FORECAST AT ALL TERMINALS BECAUSE OF THIS. ANY ACTIVITY THAT DOES OCCUR WILL NOT REDUCE VISIBILITIES. BILLINGS PREV DISCUSSION... /ISSUED 329 AM CST SUN DEC 9 2012/ DISCUSSION... TODAY-THIS EVENING: THE GUSTY NORTHWEST WINDS AND COLDEST AIR IS LAGGING BEHIND THE INITIAL WIND SHIFT. PRECIPITATION SO FAR HAS BEEN EXTREMELY LIMITED AND BASED ON LATEST MODEL RUNS...LOW LEVEL DRY AIR WILL LIKELY BE TOUGH TO OVERCOME. HOWEVER BEST SATURATION/LIFT IN TRAILING BAND FAIRLY IMPRESSIVE...BUT SO IS THE 10KFT OF DRY AIR BELOW IT. WHILE LIGHT SNOW IS LIKELY ALOFT...BELIEVE IT WILL BE VERY DIFFICULT TO GET MORE THAN SCATTERED FLURRIES TO THE GROUND. MID/UPPER LEVEL LIFT ACTUALLY INCREASES A BIT TOWARDS 0000 UTC...AND WILL LINGER FLURRIES UNTIL MIDNIGHT ACROSS EASTERN SECTIONS. TEMPERATURES WILL GENERALLY FALL THROUGHOUT THE DAY WITH COLD AIR ADVECTION FROM THE GUSTY NORTHWEST WINDS. LATE TONIGHT: TEMPERATURES WILL CONTINUE TO TUMBLE DURING THE NIGHT WITH CLEARING SKIES AND DECREASING WINDS. MODEL OUTPUT STATISTICS GUIDANCE IN GOOD AGREEMENT FOR SINGLE DIGITS FOR FAR NORTHWEST SECTIONS. MON-SAT: AFTER VERY CHILLY START TO MONDAY...EXPECT A GRADUAL MODERATION OF THE COLD AIRMASS. SHORTWAVE MOVING THROUGH MIDWEEK STILL APPEARS TO BE MOISTURE STARVED WITH ONLY SOME INCREASE IN CLOUDS. DECENT WARMUP ANTICIPATED WITH COMBINATION OF DRY AIR AND FAVORABLE SW FLOW AT H85 ON THU. MODELS HAVE DIVERGED WITH TRACK/TIMING OF SYSTEM LATE IN THE WEEK. UNFORTUNATELY...OVERALL TREND HAS LOWER CHANCES FOR PRECIPITATION ACROSS WESTERN HALF OF FORECAST AREA AS SURFACE CYCLOGENSIS DEVELOPS DRY SLOT OVER MUCH OF THE FORECAST AREA. BEST CHANCE STILL APPEARS TO BE IN SOUTHEAST KS. -HOWERTON AVIATION...06Z TAFS KRSL/KSLN/KHUT/KICT/KCNU LOW LEVEL ISENTROPIC LIFT FROM THE SOUTH-SOUTHWEST HAS LED TO WIDESPREAD IFR CONDITIONS ACROSS THE REGION LATE THIS EVENING. BOTH THE NAM/WRF AND GFS NOT HANDLING THIS LOW LEVEL MOISTURE VERY WELL...WITH THE LATEST RUC40 CLOSER TO REALITY. THE CEILINGS EVEN DROPPED LOWER THAN THE PESSIMISTIC RUC ON CEILINGS TO AROUND 6-9K FT AGL. EXPECT THE IFR CONDITIONS TO BE SHORT LIVED...AS A COLD FRONTAL BOUNDARY LOOKS TO ARRIVE AFTER 08Z-09/SUN ACROSS CENTRAL KANSAS...AND PLUNGE SOUTH ACROSS SOUTH CENTRAL KS AFTER 09-11Z/SUN. THIS WILL LEAD TO CEILINGS BEGINNING TO RAPIDLY LIFT WITH MVFR/VFR CEILINGS RETURNING BY THE MORNING HOURS ON SUN...AS LOW LEVELS QUICKLY DRY OUT. WINDS BEHIND THE FRONT WILL INCREASE TO 20-30 KTS WITH SOME LIGHT SNOW DEVELOPING ACROSS PORTIONS OF CENTRAL KANSAS EARLY SUNDAY. NOT EXPECTING THE LIGHT SNOW TO RESTRICT VSBYS MUCH WITH VFR CONDITIONS EXPECTED...AS THIS WILL BE MAINLY A LIGHT SNOW/FLURRY EVENT. KETCHAM && .PRELIMINARY POINT TEMPS/POPS... WICHITA-KICT 41 12 37 19 / 10 10 0 0 HUTCHINSON 37 11 37 21 / 10 10 0 0 NEWTON 37 12 35 20 / 10 10 0 0 ELDORADO 40 13 35 18 / 10 10 0 0 WINFIELD-KWLD 42 14 37 21 / 10 10 0 0 RUSSELL 35 4 37 19 / 10 0 0 0 GREAT BEND 34 7 37 22 / 20 0 0 0 SALINA 36 9 37 20 / 10 10 0 0 MCPHERSON 36 11 37 20 / 10 10 0 0 COFFEYVILLE 47 18 36 19 / 20 10 0 0 CHANUTE 44 14 34 18 / 20 10 0 0 IOLA 43 14 34 20 / 20 10 0 0 PARSONS-KPPF 45 17 35 16 / 20 10 0 0 && .ICT WATCHES/WARNINGS/ADVISORIES... NONE. && $$
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
546 PM EST SUN DEC 9 2012 .SYNOPSIS... A SURFACE LOW WILL PUSH NORTHEAST INTO THE OHIO VALLEY THIS EVENING AND LIFT A WARM FRONT INTO THE REGION. THIS WILL ALLOW FOR SHOWERS TO MOVE ACROSS THE AREA AND CONTINUE INTO MONDAY. A COLD FRONT WILL CROSS THE AREA ON MONDAY...ALLOWING FOR A CHANGE OVER TO SNOW SHOWERS MONDAY NIGHT WITH A MUCH COOLER AIR MASS BUILDING INTO THE AREA FOR THE MID-WEEK. && .NEAR TERM /UNTIL 6 AM MONDAY MORNING/... A BRIEF INTERLUDE SEEMS LIKELY TO ENSUE BETWEEN THE MAINLY PRE- WARM FRONTAL ISENTROPIC STRATIFORM PRECIPITATION AND THE WARM SECTOR CONVECTIVE PRECIPITATION THIS EVENING FOR MANY SECTIONS OF THE FORECAST AREA. HOWEVER...WITH THE NORTHWARD MIGRATION OF THE WARM FRONT...MID-LEVEL INSTABILITY DOES INCREASE ALL THE WHILE SYNOPTIC FORCING VIA UPPER DIVERGENCE FROM A NEARING AND SLIGHTLY ANTI-CYCLONICALLY CURVED RIGHT ENTRANCE OF AN UPPER JET STREAK COMES INTO PLAY. THE CURVATURE OF THIS JET STREAK SHOULD HELP TO GIVE ADDITIONAL AGEOSTROPHIC ENHANCEMENT OF UPPER DIVERGENCE FIELD AND THEREBY YIELD MORE STRONGLY NEGATIVE OMEGAS. THIS COUPLED WITH THE DOWNFLOW TRAJECTORY OF MID-LEVEL FORCING VIA IMPRESSIVE FRONTOGENESIS AND DIFFERENTIAL PVA AS WELL AS A FAIRLY LOW PENETRATING PV ANOMALY ON THE MODEL CONSENSUS THAT TRACKS A WEAK TROPOPAUSE FOLD FROM MISSOURI INTO NORTHERN OHIO THROUGH MONDAY WOULD FAVOR A SWATH OF HEAVIER RAINFALL JUST AHEAD OF SAID CORRIDOR. THIS WEAK FOLD IS LIKELY RESPONSIBLE FOR THE STRONG MID- LEVEL FRONTOGENESIS NOTED ON THE MODELS. GIVEN SAID SETUP...QPF GRIDS WERE INCREASED PRIMARILY FROM ZANESVILLE TO MERCER COUNTY OR SO. THE MODEL CONSENSUS FAVORS THIS FARTHER WEST QPF AXIS...WHILE THE GFS PREFERS A FARTHER EAST PLACEMENT. HOWEVER...GIVEN THE TRACK OF THE UPPER LEVEL FIELDS...THE GFS POSITIONING FAILS THE SANITY TEST AT THIS TIME. OTHER THAN MAINLY QPF AND SLIGHT POP ADJUSTMENTS THIS EVENING...THE REST OF THE FORECAST FEATURES STEADY/RISING TEMPERATURES WITH THE NORTHWARD SLOSH OF THE WARM FRONT STILL SEEMS ON TRACK. FRIES PREVIOUS DISCUSSION FOLLOWS... THE LATEST RAP MID-LEVEL ANALYSIS INDICATES A TROUGH MOVING FROM THE NORTHERN PLAINS INTO THE UPPER MIDWEST WITH THE UPPER OHIO VALLEY IN A SOUTHWESTERLY FLOW WELL AHEAD OF THIS FEATURE. AT THE SURFACE...THERE ARE TWO LOWS WELL UPSTREAM...ONE MOVING ACROSS THE UPPER MIDWEST AND ANOTHER ACROSS THE MISSOURI VALLEY. THE FRONTAL BOUNDARY BETWEEN THESE TWO LOWS IS THE DEMARCATION BETWEEN A WARM AND MOIST AIR MASS AHEAD OF IT AND ARCTIC AIR BUILDING IN BEHIND IT. A WARM FRONT EXTENDS NORTHEASTWARD FROM THE SOUTHERN LOW ACROSS SOUTHERN OHIO AND INTO CENTRAL WV. LOCALLY...THE NEXT WAVE IS RIDING ALONG AND NORTH OF THE WARM FRONT AND DEVELOPING AS IT PUSHES INTO EASTERN OHIO AND NORTH-CENTRAL WV. THIS EVENING...THE SURFACE LOW ACROSS THE MISSOURI VALLEY WILL QUICKLY LIFT INTO THE OHIO VALLEY...MERGING WITH THE LOW IN THE UPPER MIDWEST AND PULLING THE WARM FRONT NORTHWARD INTO THE UPPER OHIO VALLEY. THE AREA OF SHOWERS ASSOCIATED WITH THE SHORT WAVE IS CURRENTLY MOVING INTO THE AREA WILL SLIDE NORTHEASTWARD WITH THE WARM FRONT AND PUSH INTO WESTERN PA. MESOSCALE MODELS ARE SUPPORTIVE OF THIS FEATURE MOVING THROUGH MOST OF THE AREA BY LATE EVENING...AND THUS POPS INCREASE TO CATEGORICAL. TEMPS WILL BE SUBJECT TO THE NORTHWARD PROGRESSION OF THE WARM FRONT. LAMP/WRF-NMM SUGGEST TEMPS WILL BE SLOW TO WARM WITH A WARM SURGE OCCURRING AND HIGH TEMPS OCCURRING AFTER 21Z. TONIGHT...THE MERGED SURFACE LOW WILL CROSS THE OHIO VALLEY AND PUSH INTO THE EASTERN GREAT LAKES. ITS WARM FRONT WILL SHIFT NORTHEAST OF THE AREA AND A COLD FRONT AND ITS ASSOCIATED SURFACE TROUGH WILL BEGIN TO APPROACH FROM THE WEST. BETWEEN WARM FRONTAL SHOWERS AND SHOWERS AHEAD OF THE COLD FRONT MOVING IN FROM THE WEST...CATEGORICAL POPS ARE FORECAST THROUGH MUCH OF THE OVERNIGHT. TEMPS WILL REMAIN INCREASE A FEW DEGREES OVERNIGHT IN WAA...WITH LOWS RANGING FROM THE MID 50S IN NORTH- CENTRAL WV TO THE LOWER 30S NORTH OF THE I-80 CORRIDOR. && .SHORT TERM /6 AM MONDAY MORNING THROUGH WEDNESDAY/... GFS/NAM/ECMWF ARE IN AGREEMENT THAT THE MID-LEVEL TROUGH WILL DE-AMPLIFY AS IS SLIDES EASTWARD ACROSS THE GREAT LAKES AND PUSHES A COLD FRONT ACROSS THE UPPER OHIO VALLEY ON MONDAY. A MODEL CONSENSUS OF THE EQUIVALENT POTENTIAL TEMPERATURE GRADIENT INDICATES A COLD FRONT JUST NORTHWEST OF THE PITTSBURGH METRO AROUND 18Z ON MONDAY. AHEAD OF THE FRONT...H5 VORTICITY INDICATES ENERGY IN WAA THAT WILL ALLOW FOR SCATTERED SHOWERS AHEAD OF THE FRONT. A WELL-DEFINED SURFACE TROUGH ASSOCIATED WITH THE COLD FRONT ALONG WITH THE STRONG THERMAL GRADIENT ALONG THE FRONT WILL ALSO PROVIDE SUFFICIENT FORCING FOR SHOWERS ALONG AND BEHIND THE FRONT. WITH THIS IN MIND...CATEGORICAL POPS ARE FORECAST ACROSS THE MAJORITY OF THE AREA THROUGH 21Z. WITH THE STRENGTH OF THE FRONT...VERY WEAK INSTABILITY...AND STRONG SHEAR IN PLACE...HAVE INCLUDED A SCHC THUNDER MENTION LATE MONDAY MORNING INTO THE EARLY AFTERNOON. AHEAD OF THE FRONT...ONGOING WAA WILL ALLOW TEMPS TO BE IN THE UPPER 50S ACROSS MANY LOCATIONS WITH EVEN TEMPS NEAR 60 POSSIBLE IN NORTH-CENTRAL WV. CAA WILL ENSUE ACROSS THE ENTIRE AREA BY 00Z TUESDAY AS THE FRONT SHIFTS SOUTHEAST OF THE AREA. WITH STRONG CAA...850MB TEMPS WILL COOL TO AROUND 6-8C BY 12Z TUESDAY. 1000-500MB THICKNESS LINE DROPS SOUTHEASTWARD QUICKLY OVERNIGHT AND IN RETURN...ANY LINGERING RAIN SHOWERS WILL TURN TO SNOW SHOWERS BEHIND THE FRONT. SNOW ACCUMULATION WILL BE LIGHT...WITH A DUSTING IN MOST LOWLAND LOCATIONS AND UP TO AN INCH POSSIBLE ACROSS THE EASTERN RIDGES. LOWS ON MONDAY NIGHT WILL ARE NOT FAR FROM A MAV/MET BLEND...IN THE UPPER 20S TO LOWER 30S ACROSS THE AREA. TUESDAY INTO WEDNESDAY...HIGH PRESSURE WILL BEGIN TO BUILD IN FROM THE SOUTHWEST ON TUESDAY. A COLD WEST-NORTHWESTERLY 850MB FLOW WILL ALLOW FOR THE CHANCE OF SNOW SHOWERS TO LINGER INTO THE EARLY AFTERNOON FOR LOCATIONS NORTH AND EAST OF PITTSBURGH. 850MB FLOW THEN BACKS TO MORE SOUTHWESTERLY AND WILL ALLOW FOR DECREASING CLOUD COVERAGE TUESDAY NIGHT. AS THE HIGH MOVES OVER THE AREA ON WEDNESDAY...MORE ABUNDANT SUNSHINE IS ANTICIPATED. WITH THE CORE OF THE COOLEST AIR ACROSS THE AREA ON TUESDAY...HIGHS WILL BE AROUND A FEW DEGREES BELOW NORMAL...STRUGGLING TO REACH 40. CLEARING SKIES TUESDAY NIGHT WILL ALLOW FOR SOME RADIATIONAL COOLING...WITH LOWS IN THE LOW TO MID 20S ACROSS THE AREA. MORE SUNSHINE WEDNESDAY WILL CONTRIBUTE TO HIGHS NEAR SEASONAL VALUES. && .LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/... MODELS AGREE ON A QUIET START TO THE LONG RANGE WITH A SURFACE RIDGE AXIS EXTENDING FROM NEW ENGLAND TO THE LOWER MISSISSIPPI VALLEY DOMINATING THROUGH FRIDAY NIGHT. THIS WILL BRING DRY AND A BIT ABOVE AVERAGE TEMPERATURES. BY LATER SATURDAY A DEVELOPING STORM SYSTEM ACROSS THE CENTRAL PLAINS WILL BEGIN TO SPREAD MOISTURE ACROSS THE OHIO VALLEY WITH SHOWERS INCREASING AND CONTINUING SUNDAY AS LOW PRESSURE HEADS TO THE WESTERN GREAT LAKES. ALL RAIN EXPECTED WITH THIS SYSTEM WITH TEMPERATURES WELL ABOVE NORMAL. && .AVIATION /00Z MONDAY THROUGH FRIDAY/... GENERAL MVFR ACROSS REGION WITH OCCASIONAL VFR PATCHES MOVING ACROSS TERMINALS. AREA OF RAIN NOW INTO EASTERN OHIO WILL SPREAD ACROSS REMAINDER OF TERMINALS THIS AFTERNOON. CIGS WILL LOWER TO IFR AFTER A FEW HOURS OF RAIN BY THIS EVENING. WINDS WILL BE GENERALLY FROM THE EAST NEAR 10 KTS. UNTIL FRONT PUSHES NORTH LATER TONIGHT WHEN SOUTH WINDS AT SIMILAR SPEEDS EXPECTED. .OUTLOOK.../MONDAY THROUGH FRIDAY/... IFR RESTRICTIONS WL CONTINUE WITH RAIN MONDAY AS A COLD FRONT MOVES THROUGH. MVFR CONDITIONS ARE EXPECTED MONDAY NIGHT INTO TUESDAY. LINGERING RAIN SHOWERS MAY CHANGE TO SCATTERED SNOW SHOWERS BEFORE ENDING EARLY TUESDAY. HIGH PRES AND VFR CONDS ARE EXPECTED LATER TUESDAY NIGHT THROUGH FRIDAY. && .PBZ WATCHES/WARNINGS/ADVISORIES... MD...NONE. OH...NONE. PA...NONE. WV...NONE. && $$
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
301 PM EST SUN DEC 9 2012 .SYNOPSIS... A SURFACE LOW WILL PUSH NORTHEAST INTO THE OHIO VALLEY THIS EVENING AND LIFT A WARM FRONT INTO THE REGION. THIS WILL ALLOW FOR SHOWERS TO MOVE ACROSS THE AREA AND CONTINUE INTO MONDAY. A COLD FRONT WILL CROSS THE AREA ON MONDAY...ALLOWING FOR A CHANGE OVER TO SNOW SHOWERS MONDAY NIGHT WITH A MUCH COOLER AIR MASS BUILDING INTO THE AREA FOR THE MID-WEEK. && .NEAR TERM /THROUGH TONIGHT/... THE LATEST RAP MID-LEVEL ANALYSIS INDICATES A TROUGH MOVING FROM THE NORTHERN PLAINS INTO THE UPPER MIDWEST WITH THE UPPER OHIO VALLEY IN A SOUTHWESTERLY FLOW WELL AHEAD OF THIS FEATURE. AT THE SURFACE...THERE ARE TWO LOWS WELL UPSTREAM...ONE MOVING ACROSS THE UPPER MIDWEST AND ANOTHER ACROSS THE MISSOURI VALLEY. THE FRONTAL BOUNDARY BETWEEN THESE TWO LOWS IS THE DEMARCATION BETWEEN A WARM AND MOIST AIR MASS AHEAD OF IT AND ARCTIC AIR BUILDING IN BEHIND IT. A WARM FRONT EXTENDS NORTHEASTWARD FROM THE SOUTHERN LOW ACROSS SOUTHERN OHIO AND INTO CENTRAL WV. LOCALLY...THE NEXT WAVE IS RIDING ALONG AND NORTH OF THE WARM FRONT AND DEVELOPING AS IT PUSHES INTO EASTERN OHIO AND NORTH-CENTRAL WV. THIS EVENING...THE SURFACE LOW ACROSS THE MISSOURI VALLEY WILL QUICKLY LIFT INTO THE OHIO VALLEY...MERGING WITH THE LOW IN THE UPPER MIDWEST AND PULLING THE WARM FRONT NORTHWARD INTO THE UPPER OHIO VALLEY. THE AREA OF SHOWERS ASSOCIATED WITH THE SHORT WAVE IS CURRENTLY MOVING INTO THE AREA WILL SLIDE NORTHEASTWARD WITH THE WARM FRONT AND PUSH INTO WESTERN PA. MESOSCALE MODELS ARE SUPPORTIVE OF THIS FEATURE MOVING THROUGH MOST OF THE AREA BY LATE EVENING...AND THUS POPS INCREASE TO CATEGORICAL. TEMPS WILL BE SUBJECT TO THE NORTHWARD PROGRESSION OF THE WARM FRONT. LAMP/WRF-NMM SUGGEST TEMPS WILL BE SLOW TO WARM WITH A WARM SURGE OCCURRING AND HIGH TEMPS OCCURRING AFTER 21Z. TONIGHT...THE MERGED SURFACE LOW WILL CROSS THE OHIO VALLEY AND PUSH INTO THE EASTERN GREAT LAKES. ITS WARM FRONT WILL SHIFT NORTHEAST OF THE AREA AND A COLD FRONT AND ITS ASSOCIATED SURFACE TROUGH WILL BEGIN TO APPROACH FROM THE WEST. BETWEEN WARM FRONTAL SHOWERS AND SHOWERS AHEAD OF THE COLD FRONT MOVING IN FROM THE WEST...CATEGORICAL POPS ARE FORECAST THROUGH MUCH OF THE OVERNIGHT. TEMPS WILL REMAIN INCREASE A FEW DEGREES OVERNIGHT IN WAA...WITH LOWS RANGING FROM THE MID 50S IN NORTH- CENTRAL WV TO THE LOWER 30S NORTH OF THE I-80 CORRIDOR. && .SHORT TERM /MONDAY THROUGH WEDNESDAY/... GFS/NAM/ECMWF ARE IN AGREEMENT THAT THE MID-LEVEL TROUGH WILL DE-AMPLIFY AS IS SLIDES EASTWARD ACROSS THE GREAT LAKES AND PUSHES A COLD FRONT ACROSS THE UPPER OHIO VALLEY ON MONDAY. A MODEL CONSENSUS OF THE EQUIVALENT POTENTIAL TEMPERATURE GRADIENT INDICATES A COLD FRONT JUST NORTHWEST OF THE PITTSBURGH METRO AROUND 18Z ON MONDAY. AHEAD OF THE FRONT...H5 VORTICITY INDICATES ENERGY IN WAA THAT WILL ALLOW FOR SCATTERED SHOWERS AHEAD OF THE FRONT. A WELL-DEFINED SURFACE TROUGH ASSOCIATED WITH THE COLD FRONT ALONG WITH THE STRONG THERMAL GRADIENT ALONG THE FRONT WILL ALSO PROVIDE SUFFICIENT FORCING FOR SHOWERS ALONG AND BEHIND THE FRONT. WITH THIS IN MIND...CATEGORICAL POPS ARE FORECAST ACROSS THE MAJORITY OF THE AREA THROUGH 21Z. WITH THE STRENGTH OF THE FRONT...VERY WEAK INSTABILITY...AND STRONG SHEAR IN PLACE...HAVE INCLUDED A SCHC THUNDER MENTION LATE MONDAY MORNING INTO THE EARLY AFTERNOON. AHEAD OF THE FRONT...ONGOING WAA WILL ALLOW TEMPS TO BE IN THE UPPER 50S ACROSS MANY LOCATIONS WITH EVEN TEMPS NEAR 60 POSSIBLE IN NORTH-CENTRAL WV. CAA WILL ENSUE ACROSS THE ENTIRE AREA BY 00Z TUESDAY AS THE FRONT SHIFTS SOUTHEAST OF THE AREA. WITH STRONG CAA...850MB TEMPS WILL COOL TO AROUND 6-8C BY 12Z TUESDAY. 1000-500MB THICKNESS LINE DROPS SOUTHEASTWARD QUICKLY OVERNIGHT AND IN RETURN...ANY LINGERING RAIN SHOWERS WILL TURN TO SNOW SHOWERS BEHIND THE FRONT. SNOW ACCUMULATION WILL BE LIGHT...WITH A DUSTING IN MOST LOWLAND LOCATIONS AND UP TO AN INCH POSSIBLE ACROSS THE EASTERN RIDGES. LOWS ON MONDAY NIGHT WILL ARE NOT FAR FROM A MAV/MET BLEND...IN THE UPPER 20S TO LOWER 30S ACROSS THE AREA. TUESDAY INTO WEDNESDAY...HIGH PRESSURE WILL BEGIN TO BUILD IN FROM THE SOUTHWEST ON TUESDAY. A COLD WEST-NORTHWESTERLY 850MB FLOW WILL ALLOW FOR THE CHANCE OF SNOW SHOWERS TO LINGER INTO THE EARLY AFTERNOON FOR LOCATIONS NORTH AND EAST OF PITTSBURGH. 850MB FLOW THEN BACKS TO MORE SOUTHWESTERLY AND WILL ALLOW FOR DECREASING CLOUD COVERAGE TUESDAY NIGHT. AS THE HIGH MOVES OVER THE AREA ON WEDNESDAY...MORE ABUNDANT SUNSHINE IS ANTICIPATED. WITH THE CORE OF THE COOLEST AIR ACROSS THE AREA ON TUESDAY...HIGHS WILL BE AROUND A FEW DEGREES BELOW NORMAL...STRUGGLING TO REACH 40. CLEARING SKIES TUESDAY NIGHT WILL ALLOW FOR SOME RADIATIONAL COOLING...WITH LOWS IN THE LOW TO MID 20S ACROSS THE AREA. MORE SUNSHINE WEDNESDAY WILL CONTRIBUTE TO HIGHS NEAR SEASONAL VALUES. && .LONG TERM /WEDNESDAY NIGHT THROUGH SUNDAY/... MODELS AGREE ON A QUIET START TO THE LONG RANGE WITH A SURFACE RIDGE AXIS EXTENDING FROM NEW ENGLAND TO THE LOWER MISSISSIPPI VALLEY DOMINATING THROUGH FRIDAY NIGHT. THIS WILL BRING DRY AND A BIT ABOVE AVERAGE TEMPERATURES. BY LATER SATURDAY A DEVELOPING STORM SYSTEM ACROSS THE CENTRAL PLAINS WILL BEGIN TO SPREAD MOISTURE ACROSS THE OHIO VALLEY WITH SHOWERS INCREASING AND CONTINUING SUNDAY AS LOW PRESSURE HEADS TO THE WESTERN GREAT LAKES. ALL RAIN EXPECTED WITH THIS SYSTEM WITH TEMPERATURES WELL ABOVE NORMAL. && .AVIATION /20Z SUNDAY THROUGH FRIDAY/... GENERAL MVFR ACROSS REGION WITH OCCASIONAL VFR PATCHES MOVING ACROSS TERMINALS. AREA OF RAIN NOW INTO EASTERN OHIO WILL SPREAD ACROSS REMAINDER OF TERMINALS THIS AFTERNOON. CIGS WILL LOWER TO IFR AFTER A FEW HOURS OF RAIN BY THIS EVENING. WINDS WILL BE GENERALLY FROM THE EAST NEAR 10 KTS. UNTIL FRONT PUSHES NORTH LATER TONIGHT WHEN SOUTH WINDS AT SIMILAR SPEEDS EXPECTED. .OUTLOOK.../MONDAY THROUGH FRIDAY/... IFR RESTRICTIONS WL CONTINUE WITH RAIN MONDAY AS A COLD FRONT MOVES THROUGH. MVFR CONDITIONS ARE EXPECTED MONDAY NIGHT INTO TUESDAY. LINGERING RAIN SHOWERS MAY CHANGE TO SCATTERED SNOW SHOWERS BEFORE ENDING EARLY TUESDAY. HIGH PRES AND VFR CONDS ARE EXPECTED LATER TUESDAY NIGHT THROUGH FRIDAY. && .PBZ WATCHES/WARNINGS/ADVISORIES... MD...NONE. OH...NONE. PA...NONE. WV...NONE. && $$
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
116 PM EST SUN DEC 9 2012 .SYNOPSIS... A SURFACE LOW WILL PUSH NORTHEAST INTO THE OHIO VALLEY THIS AFTERNOON AND LIFT A WARM FRONT INTO THE REGION. THIS WILL ALLOW FOR SHOWERS TO RETURN TO THE AREA AND CONTINUE INTO MONDAY. A COLD FRONT WILL CROSS THE AREA ON MONDAY...ALLOWING FOR A CHANGE OVER TO SNOW SHOWERS MONDAY NIGHT WITH A MUCH COOLER AIR MASS BUILDING INTO THE AREA FOR THE MID-WEEK. && .NEAR TERM /THROUGH TONIGHT/... 18Z ENHANCED SHORT TERM FORECAST HAS BEEN ISSUED TO ACCOUNT FOR THE LATEST POSITION OF THE NEXT WAVE OF SHOWERS MOVING INTO THE AREA. THE LATEST RAP MID-LEVEL ANALYSIS INDICATES A TROUGH MOVING FROM THE NORTHERN PLAINS INTO THE UPPER MIDWEST WITH THE UPPER OHIO VALLEY IN A SOUTHWESTERLY FLOW WELL AHEAD OF THIS FEATURE. AT THE SURFACE...THERE ARE TWO LOWS WELL UPSTREAM...ONE MOVING ACROSS THE UPPER MIDWEST AND ANOTHER ACROSS THE MISSOURI VALLEY. THE FRONTAL BOUNDARY BETWEEN THESE TWO LOWS IS THE DEMARCATION BETWEEN A WARM AND MOIST AIR MASS AHEAD OF IT AND ARCTIC AIR BUILDING IN BEHIND IT. A WARM FRONT EXTENDS NORTHEASTWARD FROM THE SOUTHERN LOW ACROSS SOUTHERN OHIO AND INTO CENTRAL WV. LOCALLY...THE NEXT WAVE IS RIDING ALONG AND NORTH OF THE WARM FRONT AND DEVELOPING AS IT PUSHES INTO EASTERN OHIO AND NORTH-CENTRAL WV. THIS AFTERNOON...THE SURFACE LOW ACROSS THE MISSOURI VALLEY WILL QUICKLY LIFT INTO THE OHIO VALLEY...MERGING WITH THE LOW IN THE UPPER MIDWEST AND PULLING THE WARM FRONT NORTHWARD INTO THE UPPER OHIO VALLEY. THE AREA OF SHOWERS ASSOCIATED WITH THE SHORT WAVE IN CURRENTLY MOVING INTO THE AREA WILL SLIDE NORTHEASTWARD WITH THE WARM FRONT AND PUSH INTO WESTERN PA. MESOSCALE MODELS ARE SUPPORTIVE OF THIS FEATURE MOVING THROUGH MOST OF THE AREA BY LATE EVENING...AND THUS POPS INCREASE TO CATEGORICAL BY 00Z. RAP/NAM MODEL SOUNDINGS AT KZZV INDICATE SOME NARROW CAPE DEVELOPING (LESS THAN 200 J/KG) AFTER 21Z. WITH THE WARM FRONT LIFTING INTO THE AREA AND TDS SURGING INTO THE LOWER TO MID 50S...HAVE ADDED THE SCHC OF THUNDER THIS AFTERNOON INTO THE EVENING FOR LOCATIONS SOUTH AND WEST OF PITTSBURGH. TEMPS TODAY WILL SUBJECT TO THE NORTHWARD PROGRESSION OF THE WARM FRONT. LAMP/WRF-NMM SUGGEST TEMPS WILL BE SLOW TO WARM MUCH OF THE DAY WITH THE WARM SURGE OCCURRING AND HIGH TEMPS OCCURRING AFTER 21Z. THUS...WITH THE FRONT PUSHING INTO THE AREA...QUITE A THERMAL GRADIENT CAN BE EXPECTED FOR HIGHS TODAY THAT WILL RANGE FROM THE LOWER 40S IN JEFFERSON/FOREST COUNTIES TO THE LOWER 60S IN PORTIONS OF NORTH-CENTRAL WV AND EASTERN OHIO. TONIGHT...THE MERGED SURFACE LOW WILL CROSS THE OHIO VALLEY AND PUSH INTO THE EASTERN GREAT LAKES. THE WARM FRONT WILL SHIFT NORTHEAST OF THE AREA AND A COLD FRONT AND ITS ASSOCIATED SURFACE TROUGH WILL BEGIN TO APPROACH FROM THE WEST. BETWEEN WARM FRONTAL SHOWERS AND SCHC THUNDER INITIALLY AND SHOWERS AHEAD OF THE COLD FRONT MOVING IN FROM THE WEST...CATEGORICAL POPS ARE FORECAST THROUGH MUCH OF THE OVERNIGHT. TEMPS WILL DROP OFF LITTLE OVERNIGHT IN WAA...WITH LOWS RANGING FROM THE MID 50S IN NORTH-CENTRAL WV TO THE MID 40S ALONG THE I-80 CORRIDOR. && .SHORT TERM /MONDAY THROUGH WEDNESDAY/... THE SURFACE TROUGH AND COLD FRONT WILL CROSS THE AREA THROUGH THE EARLY PART OF THE DAY...WITH CATEGORICAL POPS. TEMPERATURES WILL REMAIN MILD WITH VALUES MAINLY IN THE UPPER 40S TO MID 50S INTO MIDDAY MONDAY. STRONG CAA WILL THEN BEGIN BEHIND THE FRONT...AS THE AFOREMENTIONED ARCTIC AIR MASS BEGINS TO PUSH IN FROM THE WEST. BEFORE RAIN COMES TO AN END OR CHANGES TO SNOW...CONCUR WITH HPC THAT RAINFALL AMOUNTS FOR SUNDAY INTO MONDAY WILL BE ON THE ORDER OF 1.0 TO 1.3 INCHES. CONSEQUENTLY REMAINING POSTFRONTAL SHOWERS MONDAY NIGHT WILL TURN TO SNOW SHOWERS LATE. THE POSTFRONTAL COLD POOL WILL REMAIN ACROSS THE UPPER OHIO VALLEY INTO WEDNESDAY...KEEPING SKIES MAINLY CLOUDY. HOWEVER CONDITIONS TUESDAY INTO WEDNESDAY SHOULD BE DRY AS INCOMING HIGH PRESSURE SUBSIDENCE AND LOW LEVEL WESTERLY WINDS WILL MITIGATE CHANCES OF LAKE EFFECT SNOW SHOWER DEVELOPMENT. && .LONG TERM /WEDNESDAY NIGHT THROUGH SATURDAY/... GFS ECMWF AND CANADIAN MODEL OUTPUT CONCUR THAT NEARBY HIGH PRESSURE WILL PROMOTE DRY CONDITIONS WEDNESDAY NIGHT INTO FRIDAY. ECMWF AND GFS AGREE THAT A CLOSED MID-LEVEL LOW WILL DEVELOP ACROSS THE CENTRAL PLAINS ON FRIDAY NIGHT AND SHIFT INTO THE GREAT LAKES REGION BY SATURDAY. AHEAD OF THIS FEATURE...CHANCE POPS RETURN TO THE AREA. MODEL PREDICTABILITY A WEEK OUT MAKES IT DIFFICULT TO PIN DOWN SPECIFICS IN FRONTAL PLACEMENT...HOWEVER THIS PATTERN FAVORS THE POTENTIAL FOR OVERRUNNING ALONG WITH WARM FRONTAL RAIN SHOWERS WELL AHEAD OF THE LOW. TEMPERATURES WILL REBOUND TO WARMER THAN NORMAL THIS PERIOD WITH VALUES FRIDAY AND SATURDAY ANYWHERE FROM 5 TO 10 DEGREES ABOVE NORMAL. && .AVIATION /18Z SUNDAY THROUGH FRIDAY/... GENERAL MVFR ACROSS REGION WITH OCCASIONAL VFR PATCHES MOVING ACROSS TERMINALS. AREA OF RAIN NOW MOVING INTO EASTERN OHIO AND WILL BE INTO KZZV AFTER 18Z AND SPREAD ACROSS REMAINDER OF TERMINALS THIS AFTERNOON. CIGS WILL LOWER TO IFR AFTER A FEW HOURS OF RAIN BY THIS EVENING. WINDS WILL BE GENERALLY FROM THE EAST NEAR 10 KTS. UNTIL FRONT PUSHES NORTH LATER TONIGHT WHEN SOUTH WINDS AT SIMILAR SPEEDS EXPECTED. .OUTLOOK.../MONDAY THROUGH THURSDAY/... IFR RESTRICTIONS WL CONTINUE WITH RAIN MONDAY AS A COLD FRONT MOVES THROUGH. MVFR CONDITIONS ARE EXPECTED MONDAY NIGHT INTO TUESDAY. LINGERING RAIN SHOWERS MAY CHANGE TO SCATTERED SNOW SHOWERS BEFORE ENDING EARLY TUESDAY. HIGH PRES AND VFR CONDS ARE EXPECTED LATER TUESDAY THROUGH THURSDAY. && .PBZ WATCHES/WARNINGS/ADVISORIES... MD...NONE. OH...NONE. PA...NONE. WV...NONE. && $$
AREA FORECAST DISCUSSION...UPDATED
NWS TWIN CITIES/CHANHASSEN MN
1237 PM CST SUN DEC 9 2012 .UPDATE...UPDATED FOR AVIATION DISCUSSION BELOW. && .PREV DISCUSSION.../ISSUED 1012 AM CST SUN DEC 9 2012/ .UPDATE... INCREASED THE SNOW AMOUNTS FOR TODAY INTO THIS EVENING DUE TO A SLOWER TREND OF THIS SYSTEM EXITING...IMPRESSIVE FORCING...HIGH QPF NUMBERS...AND WHAT HAS ALREADY BEEN REPORTED. MANY REPORTS OF 6 TO 10 INCHES HAVE BEEN RECEIVED ACROSS CENTRAL AND WESTERN MINNESOTA WITH AT LEAST ANOTHER 3 TO 6 INCHES EXPECTED TODAY AND THIS EVENING. FURTHER EAST TOWARD THE TWIN CITIES METRO AND FAR WRN WI...3 TO 4 INCHES WERE REPORTED THIS MORNING WITH ANOTHER 7 TO 10 EXPECTED TODAY AND THIS EVENING. THUS...HAVE A LARGE SWATH OF 9 TO 15 INCHES ACROSS MOST OF THE CWA...EXCEPT FOR FAR SOUTHERN MINNESOTA WHERE RADAR AND SATELLITE INDICATES A DRY SLOT BEGINNING TO MOVE IN. LOCALLY HIGHER AMOUNTS ARE CERTAINLY POSSIBLE. THE LOW WILL CONTINUE TRACKING DUE EAST ACROSS FAR SRN MN TODAY...SO WILL LEAVE THE HEADLINES AS THEY ARE WITH WARNINGS NORTH OF THE LOW TRACK AND AN ADVISORY ALONG AND SOUTH. A ROBUST INCREASE IN SNOW INTENSITY HAS OCCURRED IN THE PAST 30 TO 60 MINUTES FROM THE TC METRO SOUTHWEST TO REDWOOD FALLS. EXPECT RATES WITHIN THIS AREA TO REACH 1 TO 2 INCHES PER HOUR THROUGH THE REST OF THE MORNING INTO THE EARLY AFTERNOON WITH ADDITIONAL HEAVY SNOW JUST NORTH OF THE LOW TRACK LATE THIS AFTERNOON AND EARLY THIS EVENING. STRONG COLD FRONT ALONG THE MN BORDER WILL BEGIN PUSHING EAST THIS AFTERNOON. TEMPERATURES WEST OF THE BOUNDARY ARE IN THE SINGLE DIGITS WITH NORTH WINDS GUSTING HIGHER THAN 30 KTS. WHITEOUT CONDITIONS HAVE BEEN REPORTED OVER EASTERN SD. AS THE LOW PULLS EAST...EXPECT AREAS ACROSS SWRN MN TO FOLLOW SUIT. WITH REPORTS OF 6 TO 10 INCHES OVER FAR WRN MN AND SEVERAL MORE POSSIBLE...DRIFTS WILL BE RATHER SIGNIFICANT AND TRAVEL WILL BECOME IMPOSSIBLE. UPDATED THE GRIDS FOR THESE CURRENT TRENDS...INCLUDING EXTENDING THE HEAVY SNOW INTO THE EVENING ACROSS THE EAST. BORGHOFF && .PREV DISCUSSION... /ISSUED 539 AM CST SUN DEC 9 2012/ OVERVIEW...UPDATED FORECAST TO ACCOUNT FOR SOUTHERLY SHIFT OF WINTER STORM AFFECTING THE AREA TODAY. THIS PUTS THE TWIN CITIES METRO AREA RIGHT IN THE SWATH OF HEAVIEST SNOWFALL. MINOR ADJUSTMENTS TO THE WINTER WEATHER HEADLINES OVERNIGHT. ADDED MCLEOD AND MEEKER COUNTIES TO THE BLIZZARD WARNING AND LE SUEUR...RICE AND GOODHUE TO THE WINTER STORM WARNING. FRESH SNOW COVER MIGHT KEEP US A BIT COOLER THAN FORECAST TEMPERATURES THIS WEEK. NO MAJOR CHANGES TO FORECAST BEYOND THIS WEEKEND. BEEN WATCHING PERSISTENT LIGHT TO MODERATE SNOWFALL ACROSS MINNESOTA FOR THE LAST 4 TO 5 HOURS NOW. AIRPORTS REPORTING MAINLY REPORTING 3/4SM TO 1 1/2SM VISIBILITY AND A LOT OF AREA HAVE PICKED UP AND INCH OR TWO OF SNOW. FINALLY...STARTING TO GET SITES MEASURE IN WISCONSIN...BUT REALLY AREN`T SEEING MUCH HEAVY SNOW OUT THERE EARLY THIS MORNING AFTER THE INITIAL BAND NEAR THE MN/SD BORDER BROKE UP AROUND MIDNIGHT. SNOW RATES IN YELLOW MEDICINE AND LAC QUI PARLE WERE NEAR AN INCH PER HOUR LAST EVENING...WITH SITES NEAR THE STATE LINE QUICKLY PICKING UP 4-5" IN A FEW HOURS TIME. THE 00Z MPX SOUNDING...ALONG FSD AND ABR VAD PROFILES SHOW A STRONG WAA REGIME...WHICH SHOULD BE ENHANCED BY THE APPROACHING UPPER TROUGH AND INCREASING MID- LEVEL FRONTAL-GENESIS. CONSEQUENTLY...THIS BAND IS EXPECTED TO PERSIST INTO SWRN MN...FAR NERN SD...AND FAR SERN ND. SNOWFALL RATES ARE GENERALLY EXPECTED TO REMAIN BELOW 1 INCH/HOUR BUT BRIEF/ISOLATED RATES GREATER THAN 1 INCH/HOUR ARE POSSIBLE. THERE WAS GOOD MODEL CONSENSUS AMONG THE 09.00Z RUNS OF A SLIGHT SOUTHWARD SHIFT TO THE SURFACE LOW TRACK. THE RAP13 AND 00Z NAM WERE THE FIRST TO SUGGEST THIS AND THE 00Z GFS CAME ALMOST PERFECTLY IN LINE WITH THE NAM. WHAT IS A CONCERN IS THE ALMOST IDENTICAL PLACEMENT OF 14-16" SNOWFALL IN THE WEST TWIN CITIES METRO AND COUNTIES JUST WEST OF HERE. 09.00Z LOCAL WRF-ARW AND 09.08Z RAP ALSO HAVE HIGH END SNOWFALL RIGHT IN THE CENTER OF OUR CWA GIVEN THE SLOW MOVEMENT AND TRACK OF THE SURFACE/850MB/700MB LOW CENTERS. THE RAP HAS 20 INCHES...LIKELY OVERDONE BUT IT`S HINTING AT THE POTENTIAL FOR SOMETHING SIGNIFICANT. THE PV FEATURE ASSOCIATED WITH THIS SYSTEM IS IMPRESSIVE AND ITS ORIENTATION SUGGESTS A LONGER THAN EXPECTED PERIOD OF SNOW TODAY. ALREADY SEEING EVIDENCE OF A CIRCULATION IN THE REFLECTIVITY ACROSS SW MN. THIS SHOULD FEATURE SHOULD LIFT NORTH...BECOME ANCHORED PRODUCE 0.75-1.5" SNOWFALL RATES LATE THIS MORNING AND EARLY THIS AFTERNOON. INCREASED THE SNOWFALL IN THE TWIN CITIES METRO TO 8-11 INCHES...AND HOPEFULLY THAT IS ENOUGH TO COVER IT. DEPTH OF SNOW GROWTH REGION ISN`T OVERLY IMPRESSIVE...BUT WE SHOULD STILL MANAGE SNOW RATIOS NEAR CLIMATOLOGY 13-14:1 OR SO. FURTHERMORE...ON THE NOSE OF THE PV FEATURE...JUST AHEAD OF DRY SLOT...STATIC STABILITY BECOMES WEAK AND SUGGESTS BANDED PRECIP COULD BE FACTORING IN TO HELP SNOW TOTALS. OTHERWISE...WARMED TEMPS TONIGHT WITH THE SLOWER PROGRESSION AND KEPT THE WIND ABOUT THE SAME...PERHAPS A BIT LESS. THEREFORE WIND CHILLS AREN`T AS COLD WITH THIS MORNING`S FORECAST. IN THE EXTENDED...HEIGHTS BEGIN TO BUILD BACK ON WEDNESDAY...SO SHOULD ALREADY SEE MODERATING TEMPS FROM A COLD MONDAY AND TUESDAY. A COUPLE WEAK CLIPPER SYSTEM LOOK TO PASS NORTH OF THE AREA THIS WEEK...BUT THERE IS ANOTHER POTENTIALLY SIGNIFICANT STORM ON THE HORIZON 6-7 DAYS FROM NOW. && .AVIATION.../18Z TAF ISSUANCE/ WIDESPREAD MODERATE TO HEAVY SNOW CONTINUES THIS AFTERNOON FOR MOST OF THE TERMINALS. DRY SLOT AS SEEN ON RADAR IS APPROACHING RWF...BUT WILL PROBABLY STALL JUST SOUTH. NONE OF THE OTHER TERMINALS ARE EXPECTED TO BE IMPACTED BY A DRY SLOT AND WILL CONTINUE SNOWING FOR THE NEXT 6 TO 9 HOURS. BLIZZARD CONDITIONS ARE HEADED EAST ACROSS THE MN/SD BORDER AND COULD IMPACT RWF AND AXN LATER THIS AFTERNOON AND EARLY EVENING WITH SOME GUSTS TO 30 OR 35 KTS. PUSHED BACK THE CLEARING AND IMPROVING VISIBILITIES A COUPLE HOURS OVER ERN MN AND WRN WI WITH LINGERING SNOW. VFR CONDITIONS WILL REACH AXN AND RWF LATER TONIGHT...STC BY MONDAY MORNING...AND NOT UNTIL MONDAY AFTERNOON AT MSP/RNH/EAU. KMSP... A SOLID AREA OF +SN CONTINUES TO ENGULF THE TERMINAL...WHICH IS EXPECTED TO CONTINUE FOR THE MAJORITY OF THE AFTERNOON JUST NORTH OF THE LOW TRACK. DRY SLOT AS EVIDENT ON RADAR IS APPROACHING... BUT THINK IT WILL FILL IN NORTH OF THE LOW KEEPING SNOW GOING ALL AFTERNOON. SNOW WILL TAPER OFF THIS EVENING WITH OCCASIONAL LIGHT SNOW OR FLURRIES CONTINUING OVERNIGHT. SOME BLOWING SNOW IS POSSIBLE...BUT BEST CHANCES REMAIN WELL WEST. CLEARING SKIES AND IMPROVING CIGS WILL ARRIVE BY LATE MORNING MONDAY WITH VFR EXPECTED THEREAFTER. WINDS WILL BACK FROM EAST TO NORTH THIS AFTERNOON AND THEN BECOME WEST BY MONDAY AFTERNOON. /OUTLOOK FOR KMSP/ MON...MVFR/IFR CIGS POSSIBLE EARLY. THEN VFR. WINDS WNW AT 10G15KTS. TUE...MVFR/IFR CIGS POSSIBLE. FLURRIES. WINDS SW AT 10G15KTS. WED...MVFR/IFR CIGS POSSIBLE EARLY. WINDS S AT 10KTS. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...WINTER STORM WARNING UNTIL MIDNIGHT CST TONIGHT FOR ANOKA-BENTON- CARVER-CHISAGO-DAKOTA-GOODHUE-HENNEPIN-ISANTI-KANABEC-LE SUEUR-MILLE LACS-MORRISON-RAMSEY-RICE-SCOTT-SHERBURNE- STEARNS-TODD-WASHINGTON-WRIGHT. BLIZZARD WARNING UNTIL MIDNIGHT CST TONIGHT FOR BROWN-CHIPPEWA- DOUGLAS-KANDIYOHI-LAC QUI PARLE-MCLEOD-MEEKER-NICOLLET-POPE- REDWOOD-RENVILLE-SIBLEY-STEVENS-SWIFT-YELLOW MEDICINE. WINTER WEATHER ADVISORY UNTIL MIDNIGHT CST TONIGHT FOR BLUE EARTH-FARIBAULT-FREEBORN-MARTIN-STEELE-WASECA-WATONWAN. WI...WINTER STORM WARNING UNTIL MIDNIGHT CST TONIGHT FOR BARRON- CHIPPEWA-DUNN-EAU CLAIRE-PEPIN-PIERCE-POLK-RUSK-ST. CROIX. && $$ CLF/BORGHOFF
AREA FORECAST DISCUSSION...UPDATED
NWS TWIN CITIES/CHANHASSEN MN
1012 AM CST SUN DEC 9 2012 .UPDATE... INCREASED THE SNOW AMOUNTS FOR TODAY INTO THIS EVENING DUE TO A SLOWER TREND OF THIS SYSTEM EXITING...IMPRESSIVE FORCING...HIGH QPF NUMBERS...AND WHAT HAS ALREADY BEEN REPORTED. MANY REPORTS OF 6 TO 10 INCHES HAVE BEEN RECEIVED ACROSS CENTRAL AND WESTERN MINNESOTA WITH AT LEAST ANOTHER 3 TO 6 INCHES EXPECTED TODAY AND THIS EVENING. FURTHER EAST TOWARD THE TWIN CITIES METRO AND FAR WRN WI...3 TO 4 INCHES WERE REPORTED THIS MORNING WITH ANOTHER 7 TO 10 EXPECTED TODAY AND THIS EVENING. THUS...HAVE A LARGE SWATH OF 9 TO 15 INCHES ACROSS MOST OF THE CWA...EXCEPT FOR FAR SOUTHERN MINNESOTA WHERE RADAR AND SATELLITE INDICATES A DRY SLOT BEGINNING TO MOVE IN. LOCALLY HIGHER AMOUNTS ARE CERTAINLY POSSIBLE. THE LOW WILL CONTINUE TRACKING DUE EAST ACROSS FAR SRN MN TODAY...SO WILL LEAVE THE HEADLINES AS THEY ARE WITH WARNINGS NORTH OF THE LOW TRACK AND AN ADVISORY ALONG AND SOUTH. A ROBUST INCREASE IN SNOW INTENSITY HAS OCCURRED IN THE PAST 30 TO 60 MINUTES FROM THE TC METRO SOUTHWEST TO REDWOOD FALLS. EXPECT RATES WITHIN THIS AREA TO REACH 1 TO 2 INCHES PER HOUR THROUGH THE REST OF THE MORNING INTO THE EARLY AFTERNOON WITH ADDITIONAL HEAVY SNOW JUST NORTH OF THE LOW TRACK LATE THIS AFTERNOON AND EARLY THIS EVENING. STRONG COLD FRONT ALONG THE MN BORDER WILL BEGIN PUSHING EAST THIS AFTERNOON. TEMPERATURES WEST OF THE BOUNDARY ARE IN THE SINGLE DIGITS WITH NORTH WINDS GUSTING HIGHER THAN 30 KTS. WHITEOUT CONDITIONS HAVE BEEN REPORTED OVER EASTERN SD. AS THE LOW PULLS EAST...EXPECT AREAS ACROSS SWRN MN TO FOLLOW SUIT. WITH REPORTS OF 6 TO 10 INCHES OVER FAR WRN MN AND SEVERAL MORE POSSIBLE...DRIFTS WILL BE RATHER SIGNIFICANT AND TRAVEL WILL BECOME IMPOSSIBLE. UPDATED THE GRIDS FOR THESE CURRENT TRENDS...INCLUDING EXTENDING THE HEAVY SNOW INTO THE EVENING ACROSS THE EAST. BORGHOFF && .PREV DISCUSSION... /ISSUED 539 AM CST SUN DEC 9 2012/ OVERVIEW...UPDATED FORECAST TO ACCOUNT FOR SOUTHERLY SHIFT OF WINTER STORM AFFECTING THE AREA TODAY. THIS PUTS THE TWIN CITIES METRO AREA RIGHT IN THE SWATH OF HEAVIEST SNOWFALL. MINOR ADJUSTMENTS TO THE WINTER WEATHER HEADLINES OVERNIGHT. ADDED MCLEOD AND MEEKER COUNTIES TO THE BLIZZARD WARNING AND LE SUEUR...RICE AND GOODHUE TO THE WINTER STORM WARNING. FRESH SNOW COVER MIGHT KEEP US A BIT COOLER THAN FORECAST TEMPERATURES THIS WEEK. NO MAJOR CHANGES TO FORECAST BEYOND THIS WEEKEND. BEEN WATCHING PERSISTENT LIGHT TO MODERATE SNOWFALL ACROSS MINNESOTA FOR THE LAST 4 TO 5 HOURS NOW. AIRPORTS REPORTING MAINLY REPORTING 3/4SM TO 1 1/2SM VISIBILITY AND A LOT OF AREA HAVE PICKED UP AND INCH OR TWO OF SNOW. FINALLY...STARTING TO GET SITES MEASURE IN WISCONSIN...BUT REALLY AREN`T SEEING MUCH HEAVY SNOW OUT THERE EARLY THIS MORNING AFTER THE INITIAL BAND NEAR THE MN/SD BORDER BROKE UP AROUND MIDNIGHT. SNOW RATES IN YELLOW MEDICINE AND LAC QUI PARLE WERE NEAR AN INCH PER HOUR LAST EVENING...WITH SITES NEAR THE STATE LINE QUICKLY PICKING UP 4-5" IN A FEW HOURS TIME. THE 00Z MPX SOUNDING...ALONG FSD AND ABR VAD PROFILES SHOW A STRONG WAA REGIME...WHICH SHOULD BE ENHANCED BY THE APPROACHING UPPER TROUGH AND INCREASING MID- LEVEL FRONTAL-GENESIS. CONSEQUENTLY...THIS BAND IS EXPECTED TO PERSIST INTO SWRN MN...FAR NERN SD...AND FAR SERN ND. SNOWFALL RATES ARE GENERALLY EXPECTED TO REMAIN BELOW 1 INCH/HOUR BUT BRIEF/ISOLATED RATES GREATER THAN 1 INCH/HOUR ARE POSSIBLE. THERE WAS GOOD MODEL CONSENSUS AMONG THE 09.00Z RUNS OF A SLIGHT SOUTHWARD SHIFT TO THE SURFACE LOW TRACK. THE RAP13 AND 00Z NAM WERE THE FIRST TO SUGGEST THIS AND THE 00Z GFS CAME ALMOST PERFECTLY IN LINE WITH THE NAM. WHAT IS A CONCERN IS THE ALMOST IDENTICAL PLACEMENT OF 14-16" SNOWFALL IN THE WEST TWIN CITIES METRO AND COUNTIES JUST WEST OF HERE. 09.00Z LOCAL WRF-ARW AND 09.08Z RAP ALSO HAVE HIGH END SNOWFALL RIGHT IN THE CENTER OF OUR CWA GIVEN THE SLOW MOVEMENT AND TRACK OF THE SURFACE/850MB/700MB LOW CENTERS. THE RAP HAS 20 INCHES...LIKELY OVERDONE BUT IT`S HINTING AT THE POTENTIAL FOR SOMETHING SIGNIFICANT. THE PV FEATURE ASSOCIATED WITH THIS SYSTEM IS IMPRESSIVE AND ITS ORIENTATION SUGGESTS A LONGER THAN EXPECTED PERIOD OF SNOW TODAY. ALREADY SEEING EVIDENCE OF A CIRCULATION IN THE REFLECTIVITY ACROSS SW MN. THIS SHOULD FEATURE SHOULD LIFT NORTH...BECOME ANCHORED PRODUCE 0.75-1.5" SNOWFALL RATES LATE THIS MORNING AND EARLY THIS AFTERNOON. INCREASED THE SNOWFALL IN THE TWIN CITIES METRO TO 8-11 INCHES...AND HOPEFULLY THAT IS ENOUGH TO COVER IT. DEPTH OF SNOW GROWTH REGION ISN`T OVERLY IMPRESSIVE...BUT WE SHOULD STILL MANAGE SNOW RATIOS NEAR CLIMATOLOGY 13-14:1 OR SO. FURTHERMORE...ON THE NOSE OF THE PV FEATURE...JUST AHEAD OF DRY SLOT...STATIC STABILITY BECOMES WEAK AND SUGGESTS BANDED PRECIP COULD BE FACTORING IN TO HELP SNOW TOTALS. OTHERWISE...WARMED TEMPS TONIGHT WITH THE SLOWER PROGRESSION AND KEPT THE WIND ABOUT THE SAME...PERHAPS A BIT LESS. THEREFORE WIND CHILLS AREN`T AS COLD WITH THIS MORNING`S FORECAST. IN THE EXTENDED...HEIGHTS BEGIN TO BUILD BACK ON WEDNESDAY...SO SHOULD ALREADY SEE MODERATING TEMPS FROM A COLD MONDAY AND TUESDAY. A COUPLE WEAK CLIPPER SYSTEM LOOK TO PASS NORTH OF THE AREA THIS WEEK...BUT THERE IS ANOTHER POTENTIALLY SIGNIFICANT STORM ON THE HORIZON 6-7 DAYS FROM NOW. && .AVIATION.../12Z TAF ISSUANCE/ OVER THE NEXT 6 HRS...CONDS WILL DETERIORATE RAPIDLY WITH MOST TAF SITES GOING TO NEAR MINIMUMS. STORM SYSTEM WAS BEGINNING TO DEVELOP A STRONG CIRCULATION NORTHWEST OF KFSD WITH A LARGE AREA OF ENERGY THAT WILL LIFT TO THE E/NE DURING THE MORNING. SNOWFALL RATES WILL LIKELY INCREASE TO 1...OR EVEN 2 INCHES PER HOUR DURING THE HEIGHT OF THE STORM. TAFS ARE BASED ON CURRENT RAP MODEL SFC WINDS AND FORECAST REFLECTIVITY OF THE SPC/WRF. AXN WILL LIKELY BE ON THE NW SIDE OF THE LOWEST CIGS/VSBYS...WITH STC/RNH/MSP LIKELY THE WORSE AREA DURING THE 15-03Z TIME FRAME. AS THE STORM SYSTEM MOVES EASTWARD ACROSS SOUTHERN MN TODAY...EXPECT A BAND OF MODERATE TO HEAVY SNOWFALL ALONG A LINE FROM KMVE TO KMGG TO KOEO. AS THE STORM BEGINS TO PIVOT...EXPECT THE BANDS OF SNOW TO SLOWLY MOVE FROM THE WEST TO THE EAST...THEN SE AS THE STORM MOVES OFF TO THE WESTERN GREAT LAKES. THERE WILL BE A PERIOD OF 1/4SM +SN AND VV002 OR LOWER. EXPECT SFC WINDS TO INCREASE AT AXN BY 15-18Z...THAN AT RWF BY 18-21Z. AFT 00-03Z CONDS WILL SLOWLY IMPROVE WITH IFR...OR MVFR CIGS/VSBYS WITH BLSN CONTINUING ACROSS AXN/RWF. KMSP... THERE IS A 3 HR PERIOD OF IFR/MVFR CONDS WITH -SN...BUT AFT 15Z EXPECT CONDS TO DETERIORATE RAPIDLY WITH VSBYS DROPPING TO LESS THAN 3/4SM AND CIGS LOWERING TO 500` OR EVEN LOWER. THERE IS A PERIOD DURING THE AFTN WHERE VSBYS COULD DROP TO 1/4SM +SN AND VV002. SFC WINDS WILL BE PREDOMINATE FROM THE E/SE THIS MORNING/AFTN WITH SOME GUSTS OVER 20 KTS POSSIBLE BY MID MORNING. WINDS WILL SHIFT TO THE E/NE AFT 21Z...THEN BECOME N/NNE BY 00-03Z AND GUSTY. EVENTUALLY WINDS WILL SHIFT TO THE N/NNW AFT 06Z WITH CIGS/VSBYS SLOWLY IMPROVING. DECIDED NOT TO INCLUDE A TEMPORARY GROUP DUE TO UNCERTAINTIES OF TIMING OF WHEN THE WORSE CONDS DEVELOP THIS MORNING/AFTN. TAFS WILL LIKELY BE AMD AS THIS SYSTEM EVOLVES. /OUTLOOK FOR KMSP/ MON...MVFR/IFR CIGS POSSIBLE EARLY. THEN VFR. WINDS WNW AT 10G15KTS. TUE...MVFR/IFR CIGS POSSIBLE. FLURRIES. WINDS SW AT 10G15KTS. WED...MVFR/IFR CIGS POSSIBLE EARLY. WINDS S AT 10KTS. ..JLT.. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...WINTER STORM WARNING UNTIL MIDNIGHT CST TONIGHT FOR ANOKA-BENTON- CARVER-CHISAGO-DAKOTA-GOODHUE-HENNEPIN-ISANTI-KANABEC-LE SUEUR-MILLE LACS-MORRISON-RAMSEY-RICE-SCOTT-SHERBURNE- STEARNS-TODD-WASHINGTON-WRIGHT. WINTER STORM WARNING UNTIL 11 AM CST THIS MORNING FOR CHIPPEWA- DOUGLAS-KANDIYOHI-LAC QUI PARLE-MCLEOD-MEEKER-POPE-RENVILLE- SIBLEY-STEVENS-SWIFT-YELLOW MEDICINE. BLIZZARD WARNING UNTIL MIDNIGHT CST TONIGHT FOR BROWN-CHIPPEWA- DOUGLAS-KANDIYOHI-LAC QUI PARLE-MCLEOD-MEEKER-NICOLLET-POPE- REDWOOD-RENVILLE-SIBLEY-STEVENS-SWIFT-YELLOW MEDICINE. WINTER WEATHER ADVISORY UNTIL MIDNIGHT CST TONIGHT FOR BLUE EARTH-FARIBAULT-FREEBORN-MARTIN-STEELE-WASECA-WATONWAN. WINTER WEATHER ADVISORY UNTIL 11 AM CST THIS MORNING FOR BROWN- NICOLLET-REDWOOD. WI...WINTER STORM WARNING UNTIL MIDNIGHT CST TONIGHT FOR BARRON- CHIPPEWA-DUNN-EAU CLAIRE-PEPIN-PIERCE-POLK-RUSK-ST. CROIX. && $$ CLF/BORGHOFF
AREA FORECAST DISCUSSION
NWS BLACKSBURG VA
153 PM EST SUN DEC 9 2012 .SYNOPSIS... A COLD FRONT FROM NEW ENGLAND TO THE TENNESSEE VALLEY WILL MOVE SLOWLY SOUTHEAST TODAY BEFORE STALLING AND PUSHING BACK NORTH AS WARM FRONT TONIGHT. A MUCH STRONGER COLD FRONT WILL CROSS THROUGH THE AREA FROM THE WEST MONDAY EVENING. COOL HIGH PRESSURE WILL BUILD IN BEHIND THE FRONT FOR TUESDAY INTO FRIDAY. && .NEAR TERM /THROUGH TONIGHT/... AS OF 1015 AM EST SUNDAY... LATEST SURFACE OBSERVATIONS INDICATE THE COLD FRONT IS SITUATED JUST NORTHWEST OF OUR AREA THIS MORNING...STRETCHING THROUGH THE CENTRAL PORTIONS OF KENTUCKY AND WEST VIRGINIA INTO NORTHERN VIRGINIA. THE IMMEDIATE CONCERN IS A BAND OF SHOWER ACTIVITY MAKING ITS WAY ACROSS KENTUCKY...RIDING ALONG THE FRONT. EXPECT THESE SHOWERS TO SKIRT OUR MOUNTAIN EMPIRE COUNTIES BEGINNING AROUND NOON...AND CONTINUE MOVING NORTHEAST ACROSS THE ALLEGHANY HIGHLANDS THROUGH THE AFTERNOON BEFORE MOVING AWAY. SMALLER...MORE SUBTLE DISTURBANCES PASSING ACROSS THE AREA WILL TRIGGER SPOTTIER...LESS ORGANIZED SHOWER ACTIVITY ELSEWHERE THROUGH THE DAY AS WELL. AS THE DISTURBANCE TRIGGERING THESE SHOWERS MOVES NORTH...IT WILL HELP PUSH THE COLD FRONT SOUTH INTO THE FOOTHILLS. OUR LOCAL WRF AND RAP FORECAST MODELS INDICATED THE WEDGE REACHING THE ROANOKE RIVER BY THE END OF THE DAY...BEFORE ADVANCING SLOWLY BACK NORTH TONIGHT AS A WARM FRONT. HAVE MORE CLOUD COVER AND COOLER TEMPERATURES NORTH OF THE FRONT TODAY AND MORE FOG OVERNIGHT TONIGHT. USED A NON DIURNAL TREND FOR HOURLY TEMPERATURES OVERNIGHT. THOSE LOCATIONS THAT PULL OUT OF THE WEDGE WILL LIKELY WARM UP AS THEY GET BACK INTO THE WARM SECTOR. && .SHORT TERM /MONDAY THROUGH TUESDAY NIGHT/... AS OF 330 AM EST SUNDAY... PRIMARY FOCUS FOR THE SHORT TERM FORECAST WAS ON THE TIMING OF THE COLD FRONT MOVING THROUGH THE FORECAST AREA LATE MONDAY AND MONDAY NIGHT. WITH SFC WAVES RIDING UP THE SFC BOUNDARY AND INITIAL UPPER LEVEL SHORTWAVE LIFTING NORTH WITH MORE ENERGY DIGGING INTO THE BASE OF THE UPPER LEVEL TROF IN THE CENTRAL U.S....CONTINUED TO LEAN TOWARD THE SLOWER MODEL SOLUTIONS. FOR THIS FORECAST PACKAGE...THE SLOWER NAM AND SREF WERE PREFERRED. AS WINDS VEER IN RESPONSE TO THE APPROACH OF THE UPPER LEVEL TROF...SFC WEDGE SHOULD HAVE ERODED BY 12Z MONDAY...OR SHORTLY THEREAFTER...LEAVING THE ENTIRE FORECAST FIRMLY ENTRENCHED IN THE WARM SECTOR. A DEEP SOUTHWEST FLOW ALONG WITH SOME BREAKS IN THE CLOUDS IN THE EAST SHOULD ALLOW TEMPS TO SOAR WELL ABOVE NORMAL...BUT STILL BELOW RECORDS FOR 12/10. BEST 850-300MB OMEGA PER THE NAM ARRIVES IN THE WEST AROUND 18Z MONDAY...BUT LIFTS TO THE NORTH AFTERWARDS WITH UPPER LEVEL SHORTWAVE. THIS LEAVES UNCERTAINTY ON HOW FAR EAST PRECIPITATION SHIELD CAN TRAVEL. AS A RESULT...KEPT MUCH HIGHER POPS IN THE MOUNTAINS...WITH HIGH CHANCE POPS IN THE EAST LATE MONDAY AND MONDAY NIGHT. NAM FORECAST SOUNDINGS INDICATE THE LOWER LEVEL OF THE ATMOSPHERE BEGINS DRYING WHEN TEMPS COLD ENOUGH FOR SNOW BEGINS TO ARRIVE ALONG THE WESTERN SLOPES. MAY STILL BE ABLE TO SQUEEZE OUT SOME LIGHT SNOW SHOWERS IN THE HIGHEST ELEVATIONS OF SOUTHEAST WV/ALLEGHANY HIGHS FOR A FEW HOURS TUESDAY MORNING. EVEN THE SLOWEST SREF KEEPS SFC BOUNDARY WELL SOUTHEAST OF THE FORECAST AREA ON TUESDAY. WEAK SFC WAVES MOVING THROUGH EASTERN NC/VA ON TUESDAY WILL KEEP SOME CLOUDS IN THE FAR EAST...BUT LOW LEVEL NORTHWEST WINDS WILL KEEP THE FORECAST AREA DRY BY 18Z. AS SFC RIDGE QUICKLY BUILDS OVER THE AREA TUESDAY...COLD AIR ADVECTION DIMINISHES DURING THE DAY AND EXPECT TEMPS TO RECOVER AND USED A BLEND OF THE NAM/GFS MOS GUIDANCE FOR HIGHS. && .LONG TERM /WEDNESDAY THROUGH SATURDAY/... AS OF 330 PM EST SATURDAY... HIGH PRESSURE WILL CONTROL THE WEATHER PATTERN THROUGH FRIDAY. WILL BE KEEPING AN EYE ON A LOW PRESSURE SYSTEM DEVELOPING ALONG THE CAROLINA COAST OF WEDNESDAY/THURSDAY TO SEE IF ANY SHOWER ACTIVITY ADVANCES INTO THE PIEDMONTS...BUT BECOMING MORE CONFIDENT THAT THIS ACTIVITY WILL STAY EAST OF THE AREA. THE NEXT BIG STORM SYSTEM TO WATCH WILL ARRIVE NEXT WEEKEND AS A DEEP LOW PRESSURE SYSTEM PASSES EASTWARD FROM THE CENTRAL PLAINS INTO THE GREAT LAKES...DRAGGING A COLD FRONT TOWARD OUR AREA. && .AVIATION /18Z SUNDAY THROUGH FRIDAY/... AS OF 130 PM EST SUNDAY... SURFACE OBSERVATIONS INDICATE THAT WHILE VISIBILITIES HAVE IMPROVED WITH AFTERNOON HEATING...AREAS OF LIFR TO MVFR CEILINGS REMAIN ACROSS THE AREA...INTERMIXED WITH VFR CEILINGS. ALSO CONCERNED WITH TWO AREAS OF SHOWER ACTIVITY...A SMALL AREA THAT WILL BRIEFLY AFFECT DAN BETWEEN 19Z AND 21Z...AND A MUCH LARGER AREA STRETCHING FROM EASTERN TENNESSEE THROUGH NORTHERN WEST VIRGINIA...MOVING TO THE NORTHEAST ALONG A COLD FRONT SITUATED ACROSS THE AREA. EAST OF THE MOUNTAINS...ALSO OBSERVING THE SAME COLD FRONT BUILD SOUTHWARD ACROSS THE PIEDMONTS AS A BACKDOOR FRONT...ALREADY HAVING PASSED THROUGH LYH...AS EVIDENCED BY MVFR STRATOCU MOVING IN FROM THE NORTHEAST. WHILE THE MAJORITY OF THE SHOWER ACTIVITY WILL REMAIN WEST OF THE AREA THIS AFTERNOON...EXPECT SOME OF THESE SHOWERS TO SPILL OVER THE MOUNTAINS...AFFECTING BLF AND LWB DURING EARLY TO MID EVENING...BEFORE PUSHING AWAY FROM THE AREA BEFORE MIDNIGHT MONDAY. EXPECT MVFR FOG MOST LOCATIONS AGAIN TONIGHT. DEPENDS ON HOW FAR THE BACKDOOR FRONT ADVANCES WEST...EVEN ROA MAY HAVE MVFR FOG. ALSO CONCERNED WITH LOW LEVEL WIND SHEAR DUE TO STRENGTHENING LOW LEVEL JET. MODELS HAVE WINDS JUST ABOVE THE SURFACE FROM THE SOUTHWEST AT 30 TO 40 KNOTS...AND HAVE THEREFORE MENTIONED IN THE TAFS. EXPECT THE BACKDOOR FRONT TO LIFT NORTHWARD AGAIN SHORTLY BEFORE SUNRISE AS A DEEP LOW PRESSURE SYSTEM PASSES ACROSS THE GREAT LAKES. ON MONDAY AFTERNOON...A STRONG COLD FRONT WILL ENTER THE FORECAST AREA...PASSING ACROSS BLF AND LWB AOA 10/20Z...AND MOVING ACROSS DAN AND LYH AOA 11/03Z. EXPECT GUSTY NORTHWEST WINDS BEHIND THE FRONT ON MONDAY NIGHT AND TUESDAY. CONDITIONS WILL IMPROVE ON TUESDAY EVENING AS HIGH PRESSURE BEGINS TO SETTLE ACROSS THE AREA. LINGERING MOISTURE IN THE MOUNTAINS TUESDAY WILL RESULT IN MVFR CONDITIONS AND THE POSSIBILITY OF SNOW SHOWERS AS COLDER AIR SURGES INTO THE AREA. VFR CONDITIONS WILL RETURN FOR TUESDAY NIGHT THROUGH FRIDAY. && .RNK WATCHES/WARNINGS/ADVISORIES... VA...NONE. NC...NONE. WV...NONE. && $$ SYNOPSIS...AMS NEAR TERM...AMS/NF SHORT TERM...PH LONG TERM...NF AVIATION...AMS/NF