Forecast Discussions mentioning any of "HRRR" "RAP" "RR" "RUC13" "RUC" received at GSD on 04/18/13


AREA FORECAST DISCUSSION
NWS DENVER/BOULDER CO
1210 PM MDT TUE APR 16 2013 .UPDATE... && .SHORT TERM...TAKING A CLOSER LOOK AT THE LATEST MODELS...NOW APPEARS THE DEVELOPMENT OF SNOW ACROSS THE PLAINS MAY BE DELAYED A BIT LONGER OVERNIGHT...PERHAPS NOT UNTIL 10Z. WILL KEEP THE BETTER POPS AND WEATHER TOWARDS THE WYOMING BODER. .AVIATION...LATEST MODELS NOW SHOWING WINDS GO COUNTERCLOCKWISE LATER THIS EVENING AND OVERNIGHT WHICH COULD BRING SOME LOW STRATUS AND PERHAPS FOG ACROSS THE AREA AIRPORTS AFTER 06Z. IT ALSO APPEARS THE DEVELOPMENT OF LIGHT SNOW MAY ALSO BE DELAYED. LATEST TAFS INDICATE THIS LATEST CHANCE. STILL POTENTIAL FOR 2 TO 4 INCHES ACROSS DENVER AREA BY 00Z. && .PREV DISCUSSION... /ISSUED 1059 AM MDT TUE APR 16 2013/ UPDATE... SHORT TERM...STILL SEEMS FROM WEB CAMS THAT A FEW FLURRIES STILL ONGOING ALONG THE CHEYENNE RIDGE AS WELL AS THE FOOTHILLS...THOUGH HAVE BEEN ON THE DECREASE. ALSO APPEARS ANY FREEZING DRIZZLE THREAT HAS ENDED. SOUTHEAST WINDS CURRENTLY CRANKING ACROSS MUCH OF THE PLAINS...WITH SOME GUSTS AROUND 30 KTS FROM DENVER AREA EASTWARD. WEAK CYCLONE NORTH OF DENVER KEEPING LIGHT NORTHWEST WINDS NORTHWEST DENVER SUBURBS. OTHERWISE...SOUTHWEST FLOW ALOFT PREVAILING THROUGH TONIGHT AS UPPER TROUGH DIGS INTO THE GREAT BASIN. SOUTHEAST WINDS EXPECTED TO CONTINUE THROUGH THE DAY ACROSS THE PLAINS WITH UPPER TROUGH OVER GREAT BASIN. AIRMASS BECOMES SLIGHTLY UNSTABLE DURING THE AFTERNOON WITH LAPSE RATES APPROACHING 8 C/KM OVER MOUNTAINS AND AROUND 7 C/KM IN THE MID LEVELS ACROSS PLAINS. STILL SOME CHANCE OF SHOWERS THIS AFTERNOON MAINLY OVER THE MOUNTAINS...WILL CONTINUE CURRENT POPS AND WEATHER TRENDS THERE. AS FOR PLAINS...SCATTERED POPS MAY BE A BIT OVERDONE THROUGH 00Z BASED ON LATEST RAP. BUT THERE WILL BE SOME INCREASE IN MID LEVEL QG ASCENT WHICH COULD PROVIDE SOME CONVECTIVE ELEMENTS WITH THE BEST CHANCE TO BE IN AND NEAR NORTHERN FOOTHILLS. LATEST MODELS STILL POINTING TOWARD NORTHERN MOUNTAINS AND NORTHERN FOOTHILLS TONIGHT FOR DECENT SNOW FALL WITH POTENTIAL FOR JET DYNAMICS AND CSI. AT SOME POINT...MAY NEED AN ADVISORY FOR ZONES 30..32 AND 34 TONIGHT AS CSI BANDS COULD SET UP THERE. WILL ADDRESS THIS FOR THE AFTERNOON PACKAGE. OVERALL...CURRENT FORECASTS SEEM ON TRACK...WITH PERHAPS A BIT MORE WIND NEEDED ACROSS PLAINS. TEMPERATURES LOOK REASONABLE. $$ ,AVIATION...SOME FOG AND OR HAZE STILL FLOATING AROUND AREA AIRPORTS...WILL KEEP A MENTION THROUGH 19Z. SOUTHEAST WINDS CURRENTLY GUSTING TO AROUND 25-30 KTS AT KDEN AND KAPA...WHICH SHOULD CONTINUE THROUGH THE AFTERNOON PER LATEST RAP AND HRRR. CYCLONE NORTH OF DENVER TO PERSIST THROUGH THE DAY...SHOULD KEEP LIGHT NORTHWEST WINDS AT KBJC. OTHERWISE...CURRENT TAF TRENDS SEEM ON TRACK. CEILINGS TO GRADUALLY IMPROVE...STILL 5000-6000 FOOT CEILINGS TO PREVAIL. A FEW SHOWERS POSSIBLE ALONG FOOTHILLS DURING THE AFTERNOON AND EVENING. BETTER CHANCE FOR SNOW SHOWERS AT AREA AIRPORTS AFTER MIDNIGHT TONIGHT. ACCUMULATION SNOW POSSIBLE DURING THE DAY WEDNESDAY WHEN DEEPER UPSLOPE FLOW DEVELOPS WITH 2 TO 4 INCHES POSSIBLE BY 00Z. PREV DISCUSSION... /ISSUED 428 AM MDT TUE APR 16 2013/ SHORT TERM...HEAVY SNOW BAND ALONG WITH THE UPPER LEVEL JET HAD SHIFTED NORTH INTO WYOMING EARLY THIS MORNING. AS A RESULT... EXISTING WINTER STORM HIGHLIGHTS HAVE BEEN CANCELLED. BEHIND THIS...THERE WERE STILL SNOW SHOWERS MAINLY IN THE NORTHERN MOUNTAINS AND NORTHERN FRONT RANGE FOOTHILLS. SOME FREEZING DRIZZLE HAD ALSO DEVELOPED ACROSS THE PLAINS WITH MOIST LOW LEVEL EASTERLY UPSLOPE FLOW. LACK OF SEEDERS ALOFT SHOULD KEEP THREAT OF FREEZING DRIZZLE IN THE FORECAST THIS MORNING. ATTENTION THEN TURNS TOWARD CONVECTIVE SHOWER DEVELOPMENT THIS AFTERNOON WHICH SHOULD AFFECT MAINLY THE MOUNTAIN AREAS WHERE INSTABILITY IS SUFFICIENT. BY THIS EVENING...THE VARIOUS SHORT AND MEDIUM RANGE MODELS SUGGEST A DEEPER SOUTHEAST FLOW DEVELOPING WHICH FAVORS THE NORTHERN FRONT RANGE FOOTHILLS FOR PRECIP. THE POTENTIAL FOR HEAVY SNOWFALL LIKELY DEPENDS ON LOCATION OF UPPER JET AND DRY SLOT...WHICH AT THIS TIME SHOULD BE JUST FAR ENOUGH SOUTH TO BRING HEAVY SNOW THREAT BACK INTO THE NORTHERN TIER OF MOUNTAINS AND THE LARIMER COUNTY FOOTHILLS LATER THIS AFTERNOON THROUGH TONIGHT. AT THIS POINT...THE PROBABILITY IS HIGH ENOUGH TO ISSUE ANOTHER WINTER STORM WARNING BEGINNING IN THOSE LOCATIONS LATER THIS AFTERNOON. AGAIN...THERE WILL LIKELY BE ANOTHER VERY SHARP CUTOFF OF SIGNIFICATION PRECIPITATION JUST SOUTH OF THE JET SO SITUATION WILL NEED TO MONITORED CLOSELY. ON THE PLAINS...LOW LEVEL SOUTHEAST FLOW WILL STRENGTHEN CONSIDERABLY TODAY. HOWEVER...COOLER BOUNDARY LAYER FLOW SHOULD REMAIN IN PLACE WITH PLENTY OF LOW LEVEL MOISTURE...CLOUDINESS... AND SNOW IN AREAS THAT SAW THE HEAVY ACCUMULATIONS YESTERDAY. THE SOUTHEAST FLOW AND SNOWPACK LOCATION SHOULD SET UP A STRONG DENVER CYCLONE THIS AFTERNOON...KEEPING COLD AIR IN PLACE FROM THE WESTERN SECTIONS OF DENVER NORTHWARD TO FORT COLLINS. COULD SEE A FEW RAIN OR SNOW SHOWERS DRIFT OFF THE FRONT RANGE LATER THIS AFTERNOON BUT BETTER CHANCE OF SNOW DEVELOPING WILL OCCUR LATER TONIGHT AS MOISTURE BEGINS TO DEEPEN AHEAD OF DIGGING TROUGH. LONG TERM...UPPER TROUGH DRAPED OVER THE GREAT BASIN WILL MOVE SOUTHEAST WEDNESDAY AND SEND A COLD FRONT RACING DOWN NORTHEASTERN COLORADO DURING THE MORNING. UPSLOPE FLOW WILL FORM AGAINST THE FOOTHILLS DURING THE DAY TO KEEP SNOW GOING THROUGH THE AFTERNOON AT LEAST. SNOW WILL SPREAD OVER THE PLAINS BEHIND THE FRONT AND AS THE UPSLOPE DEEPENS. NORTH WINDS BEHIND THE FRONT...GUSTING 30 TO 40 MPH OVER THE PLAINS WILL REMAIN THROUGHOUT WEDNESDAY DAY TO CREATE SOME AREAS OF BLOWING AND DRIFTING SNOW. RIGHT NOW WILL NOT ISSUE ANY HIGHLIGHTS AS THERE MAY BE A PERIOD OF RAIN MIXED WITH SNOW OVER THE PLAINS LIMITING THE AMOUNT OF BLOWING SNOW. OTHERWISE ALL PRECIP IS EXPECTED TO BE SNOW AS 700 TEMPS OF -14 CELSIUS SPREAD IN BEHIND THE FRONT. THE 700 MB LOW WILL TRANSITION OVER THE COLORADO PLAINS SOMETIME LATE AFTERNOON INTO THE EVENING...WHICH WILL BEGIN TO DIMINISH THE SNOW FROM NORTHWEST TO SOUTHEAST. SNOW SHOULD BE DIMINISHED JUST AFTER SUNSET IN MOST AREAS EXCEPT THE FAR EASTERN PLAINS AND SOME LIGHT SNOW OVER THE MOUNTAINS...UNLESS THIS SYSTEM DIGS A LITTLE FARTHER SOUTH AND DEEPER WHICH WOULD SLOW IT DOWN. OVERALL...AMOUNTS WEDNESDAY AND WEDNESDAY NIGHT LOOK TO BE ABOUT 2-5 INCHES OVER THE PLAINS AND 3-9 INCHES OVER THE MOUNTAINS...WITH THE LOWER AMOUNTS IN THE VALLEYS. TEMPERATURES WEDNESDAY NIGHT WILL LIKELY BE IN THE TEENS OVER THE PLAINS TO SINGLE DIGITS OVER THE MOUNTAINS. THE UPPER LOW WILL MOVE EAST OF THE AREA THURSDAY. SHOULD SEE SNOW SLOWLY DIMINISHING OVER THE MOUNTAINS AND A CHANCE OF SNOW CONTINUING OVER THE FAR EASTERN PLAINS...BUT SHOULD BE DONE BY LATE AFTERNOON. TEMPERATURES WILL BE WARMING SLIGHTLY BUT WILL STILL BE AROUND 20 TO 30 DEGREES BELOW NORMAL. FRIDAY WILL CONTINUE THE WARMING AND DRYING TREND AS A WEAK UPPER RIDGE BUILDS OVERHEAD. SATURDAY THROUGH MONDAY WILL FEATURE A COUPLE DISTURBANCES IN THE NORTHWEST FLOW ALOFT TO BRING A RETURN TO UNSETTLED WEATHER. WILL SEE AN INCREASE IN THE CHANCES OF PRECIPITATION AGAIN FOR THE AREA. TEMPERATURES WILL BE BACK TOWARD NORMAL....BUT STILL SLIGHTLY BELOW AVERAGE. THEREFORE WILL EXPECT MORE RAIN FOR THE PLAINS AND CONTINUED RAIN MIXED WITH SNOW FOR THE MOUNTAINS. AVIATION...AREAS OF IFR/LIFR CEILINGS EXPECTED ACROSS THE FRONT RANGE AIRPORTS THIS MORNING ALONG WITH A THREAT OF LIGHT FREEZING DRIZZLE GIVEN TEMP/MOISTURE PROFILE IN PLACE. IF WE SEE ANY SNOW WE DO NOT SEE ANY THREAT OF ACCUMULATION WITH ONLY FLURRIES POSSIBLE. CEILING SHOULD GRADUALLY LIFT TODAY AT KDEN AND KAPA WITH POSSIBLE EAST/SOUTHEAST WINDS GUSTING TO AROUND 25KTS. KBJC WILL LIKELY SEE LOWER PREVAILING CONDITIONS ON BACK SIDE OF CYCLONE. CHANCE THAT WINDS GO BACK TO NORTH OR NORTHWEST AT KAPA AND KDEN THIS AFTERNOON DEPENDING ON INTENSITY OF DENVER CYCLONE THAT DEVELOPS. BEST CHANCE OF SNOW WILL BE AFTER MIDNIGHT TONIGHT AND MAINLY WEDNESDAY WHEN DEEPER UPSLOPE FLOW OCCURS. COULD SEE ANOTHER 2-5 INCHES OF SNOW LATE TONIGHT/WEDNESDAY. && .BOU WATCHES/WARNINGS/ADVISORIES... WINTER STORM WARNING FROM 3 PM THIS AFTERNOON TO MIDNIGHT MDT WEDNESDAY NIGHT FOR COZ031-033-035. && $$ SHORT TERM...D-L LONG TERM....KRIEDERMAN AVIATION...D-L
AREA FORECAST DISCUSSION
NWS DENVER/BOULDER CO
1059 AM MDT TUE APR 16 2013 .UPDATE... && .SHORT TERM...STILL SEEMS FROM WEB CAMS THAT A FEW FLURRIES STILL ONGOING ALONG THE CHEYENNE RIDGE AS WELL AS THE FOOTHILLS...THOUGH HAVE BEEN ON THE DECREASE. ALSO APPEARS ANY FREEZING DRIZZLE THREAT HAS ENDED. SOUTHEAST WINDS CURRENTLY CRANKING ACROSS MUCH OF THE PLAINS...WITH SOME GUSTS AROUND 30 KTS FROM DENVER AREA EASTWARD. WEAK CYCLONE NORTH OF DENVER KEEPING LIGHT NORTHWEST WINDS NORTHWEST DENVER SUBURBS. OTHERWISE...SOUTHWEST FLOW ALOFT PREVAILING THROUGH TONIGHT AS UPPER TROUGH DIGS INTO THE GREAT BASIN. SOUTHEAST WINDS EXPECTED TO CONTINUE THROUGH THE DAY ACROSS THE PLAINS WITH UPPER TROUGH OVER GREAT BASIN. AIRMASS BECOMES SLIGHTLY UNSTABLE DURING THE AFTERNOON WITH LAPSE RATES APPROACHING 8 C/KM OVER MOUNTAINS AND AROUND 7 C/KM IN THE MID LEVELS ACROSS PLAINS. STILL SOME CHANCE OF SHOWERS THIS AFTERNOON MAINLY OVER THE MOUNTAINS...WILL CONTINUE CURRENT POPS AND WEATHER TRENDS THERE. AS FOR PLAINS...SCATTERED POPS MAY BE A BIT OVERDONE THROUGH 00Z BASED ON LATEST RAP. BUT THERE WILL BE SOME INCREASE IN MID LEVEL QG ASCENT WHICH COULD PROVIDE SOME CONVECTIVE ELEMENTS WITH THE BEST CHANCE TO BE IN AND NEAR NORTHERN FOOTHILLS. LATEST MODELS STILL POINTING TOWARD NORTHERN MOUNTAINS AND NORTHERN FOOTHILLS TONIGHT FOR DECENT SNOW FALL WITH POTENTIAL FOR JET DYNAMICS AND CSI. AT SOME POINT...MAY NEED AN ADVISORY FOR ZONES 30..32 AND 34 TONIGHT AS CSI BANDS COULD SET UP THERE. WILL ADDRESS THIS FOR THE AFTERNOON PACKAGE. OVERALL...CURRENT FORECASTS SEEM ON TRACK...WITH PERHAPS A BIT MORE WIND NEEDED ACROSS PLAINS. TEMPERATURES LOOK REASONABLE. $$ ,AVIATION...SOME FOG AND OR HAZE STILL FLOATING AROUND AREA AIRPORTS...WILL KEEP A MENTION THROUGH 19Z. SOUTHEAST WINDS CURRENTLY GUSTING TO AROUND 25-30 KTS AT KDEN AND KAPA...WHICH SHOULD CONTINUE THROUGH THE AFTERNOON PER LATEST RAP AND HRRR. CYCLONE NORTH OF DENVER TO PERSIST THROUGH THE DAY...SHOULD KEEP LIGHT NORTHWEST WINDS AT KBJC. OTHERWISE...CURRENT TAF TRENDS SEEM ON TRACK. CEILINGS TO GRADUALLY IMPROVE...STILL 5000-6000 FOOT CEILINGS TO PREVAIL. A FEW SHOWERS POSSIBLE ALONG FOOTHILLS DURING THE AFTERNOON AND EVENING. BETTER CHANCE FOR SNOW SHOWERS AT AREA AIRPORTS AFTER MIDNIGHT TONIGHT. ACCUMULATION SNOW POSSIBLE DURING THE DAY WEDNESDAY WHEN DEEPER UPSLOPE FLOW DEVELOPS WITH 2 TO 4 INCHES POSSIBLE BY 00Z. && .PREV DISCUSSION... /ISSUED 428 AM MDT TUE APR 16 2013/ SHORT TERM...HEAVY SNOW BAND ALONG WITH THE UPPER LEVEL JET HAD SHIFTED NORTH INTO WYOMING EARLY THIS MORNING. AS A RESULT... EXISTING WINTER STORM HIGHLIGHTS HAVE BEEN CANCELLED. BEHIND THIS...THERE WERE STILL SNOW SHOWERS MAINLY IN THE NORTHERN MOUNTAINS AND NORTHERN FRONT RANGE FOOTHILLS. SOME FREEZING DRIZZLE HAD ALSO DEVELOPED ACROSS THE PLAINS WITH MOIST LOW LEVEL EASTERLY UPSLOPE FLOW. LACK OF SEEDERS ALOFT SHOULD KEEP THREAT OF FREEZING DRIZZLE IN THE FORECAST THIS MORNING. ATTENTION THEN TURNS TOWARD CONVECTIVE SHOWER DEVELOPMENT THIS AFTERNOON WHICH SHOULD AFFECT MAINLY THE MOUNTAIN AREAS WHERE INSTABILITY IS SUFFICIENT. BY THIS EVENING...THE VARIOUS SHORT AND MEDIUM RANGE MODELS SUGGEST A DEEPER SOUTHEAST FLOW DEVELOPING WHICH FAVORS THE NORTHERN FRONT RANGE FOOTHILLS FOR PRECIP. THE POTENTIAL FOR HEAVY SNOWFALL LIKELY DEPENDS ON LOCATION OF UPPER JET AND DRY SLOT...WHICH AT THIS TIME SHOULD BE JUST FAR ENOUGH SOUTH TO BRING HEAVY SNOW THREAT BACK INTO THE NORTHERN TIER OF MOUNTAINS AND THE LARIMER COUNTY FOOTHILLS LATER THIS AFTERNOON THROUGH TONIGHT. AT THIS POINT...THE PROBABILITY IS HIGH ENOUGH TO ISSUE ANOTHER WINTER STORM WARNING BEGINNING IN THOSE LOCATIONS LATER THIS AFTERNOON. AGAIN...THERE WILL LIKELY BE ANOTHER VERY SHARP CUTOFF OF SIGNIFICATION PRECIPITATION JUST SOUTH OF THE JET SO SITUATION WILL NEED TO MONITORED CLOSELY. ON THE PLAINS...LOW LEVEL SOUTHEAST FLOW WILL STRENGTHEN CONSIDERABLY TODAY. HOWEVER...COOLER BOUNDARY LAYER FLOW SHOULD REMAIN IN PLACE WITH PLENTY OF LOW LEVEL MOISTURE...CLOUDINESS... AND SNOW IN AREAS THAT SAW THE HEAVY ACCUMULATIONS YESTERDAY. THE SOUTHEAST FLOW AND SNOWPACK LOCATION SHOULD SET UP A STRONG DENVER CYCLONE THIS AFTERNOON...KEEPING COLD AIR IN PLACE FROM THE WESTERN SECTIONS OF DENVER NORTHWARD TO FORT COLLINS. COULD SEE A FEW RAIN OR SNOW SHOWERS DRIFT OFF THE FRONT RANGE LATER THIS AFTERNOON BUT BETTER CHANCE OF SNOW DEVELOPING WILL OCCUR LATER TONIGHT AS MOISTURE BEGINS TO DEEPEN AHEAD OF DIGGING TROUGH. LONG TERM...UPPER TROUGH DRAPED OVER THE GREAT BASIN WILL MOVE SOUTHEAST WEDNESDAY AND SEND A COLD FRONT RACING DOWN NORTHEASTERN COLORADO DURING THE MORNING. UPSLOPE FLOW WILL FORM AGAINST THE FOOTHILLS DURING THE DAY TO KEEP SNOW GOING THROUGH THE AFTERNOON AT LEAST. SNOW WILL SPREAD OVER THE PLAINS BEHIND THE FRONT AND AS THE UPSLOPE DEEPENS. NORTH WINDS BEHIND THE FRONT...GUSTING 30 TO 40 MPH OVER THE PLAINS WILL REMAIN THROUGHOUT WEDNESDAY DAY TO CREATE SOME AREAS OF BLOWING AND DRIFTING SNOW. RIGHT NOW WILL NOT ISSUE ANY HIGHLIGHTS AS THERE MAY BE A PERIOD OF RAIN MIXED WITH SNOW OVER THE PLAINS LIMITING THE AMOUNT OF BLOWING SNOW. OTHERWISE ALL PRECIP IS EXPECTED TO BE SNOW AS 700 TEMPS OF -14 CELSIUS SPREAD IN BEHIND THE FRONT. THE 700 MB LOW WILL TRANSITION OVER THE COLORADO PLAINS SOMETIME LATE AFTERNOON INTO THE EVENING...WHICH WILL BEGIN TO DIMINISH THE SNOW FROM NORTHWEST TO SOUTHEAST. SNOW SHOULD BE DIMINISHED JUST AFTER SUNSET IN MOST AREAS EXCEPT THE FAR EASTERN PLAINS AND SOME LIGHT SNOW OVER THE MOUNTAINS...UNLESS THIS SYSTEM DIGS A LITTLE FARTHER SOUTH AND DEEPER WHICH WOULD SLOW IT DOWN. OVERALL...AMOUNTS WEDNESDAY AND WEDNESDAY NIGHT LOOK TO BE ABOUT 2-5 INCHES OVER THE PLAINS AND 3-9 INCHES OVER THE MOUNTAINS...WITH THE LOWER AMOUNTS IN THE VALLEYS. TEMPERATURES WEDNESDAY NIGHT WILL LIKELY BE IN THE TEENS OVER THE PLAINS TO SINGLE DIGITS OVER THE MOUNTAINS. THE UPPER LOW WILL MOVE EAST OF THE AREA THURSDAY. SHOULD SEE SNOW SLOWLY DIMINISHING OVER THE MOUNTAINS AND A CHANCE OF SNOW CONTINUING OVER THE FAR EASTERN PLAINS...BUT SHOULD BE DONE BY LATE AFTERNOON. TEMPERATURES WILL BE WARMING SLIGHTLY BUT WILL STILL BE AROUND 20 TO 30 DEGREES BELOW NORMAL. FRIDAY WILL CONTINUE THE WARMING AND DRYING TREND AS A WEAK UPPER RIDGE BUILDS OVERHEAD. SATURDAY THROUGH MONDAY WILL FEATURE A COUPLE DISTURBANCES IN THE NORTHWEST FLOW ALOFT TO BRING A RETURN TO UNSETTLED WEATHER. WILL SEE AN INCREASE IN THE CHANCES OF PRECIPITATION AGAIN FOR THE AREA. TEMPERATURES WILL BE BACK TOWARD NORMAL....BUT STILL SLIGHTLY BELOW AVERAGE. THEREFORE WILL EXPECT MORE RAIN FOR THE PLAINS AND CONTINUED RAIN MIXED WITH SNOW FOR THE MOUNTAINS. AVIATION...AREAS OF IFR/LIFR CEILINGS EXPECTED ACROSS THE FRONT RANGE AIRPORTS THIS MORNING ALONG WITH A THREAT OF LIGHT FREEZING DRIZZLE GIVEN TEMP/MOISTURE PROFILE IN PLACE. IF WE SEE ANY SNOW WE DO NOT SEE ANY THREAT OF ACCUMULATION WITH ONLY FLURRIES POSSIBLE. CEILING SHOULD GRADUALLY LIFT TODAY AT KDEN AND KAPA WITH POSSIBLE EAST/SOUTHEAST WINDS GUSTING TO AROUND 25KTS. KBJC WILL LIKELY SEE LOWER PREVAILING CONDITIONS ON BACK SIDE OF CYCLONE. CHANCE THAT WINDS GO BACK TO NORTH OR NORTHWEST AT KAPA AND KDEN THIS AFTERNOON DEPENDING ON INTENSITY OF DENVER CYCLONE THAT DEVELOPS. BEST CHANCE OF SNOW WILL BE AFTER MIDNIGHT TONIGHT AND MAINLY WEDNESDAY WHEN DEEPER UPSLOPE FLOW OCCURS. COULD SEE ANOTHER 2-5 INCHES OF SNOW LATE TONIGHT/WEDNESDAY. && .BOU WATCHES/WARNINGS/ADVISORIES... WINTER STORM WARNING FROM 3 PM THIS AFTERNOON TO MIDNIGHT MDT WEDNESDAY NIGHT FOR COZ031-033-035. && $$ SHORT TERM...D-L LONG TERM....KRIEDERMAN AVIATION...D-L
AREA FORECAST DISCUSSION
NWS TALLAHASSEE FL
839 PM EDT Wed Apr 17 2013 .NEAR TERM [Through Tonight]... The primary concern over the CWA for the overnight hours continues to be the potential for the development of Low clouds and/or Fog, mainly after the fairly thick Upper level canopy exits to our east. As of early this evening, the back edge of this Upper level cloud shield has reached the western FL Panhandle and south-central AL, and it is continuing to make steady progress to the east. That said, the trends in the latest model guidance (from numerical to Hi-Res) are starting to back off on the Fog Potential across the region, while still favoring some Low Cigs over eastern portions of the CWA, mainly towards morning. There is excellent agreement between the NARRE and the HRRR on this solution, with other indicators in the Nam, WRF, and numerical guidance from the GFS supporting this as well. Sfc winds expected to remain in the 4-6 kt range are not favorable for Fog. Therefore, will trim back the patchy fog in the grids to focus on the east, and will also tweak the sky grids to show greater low level cloud cover to the east as well. Otherwise, the current fcst is on track with only minor adjustments expected. && .SHORT TERM [Thursday Through Friday Night]... Short term weather concerns will remain dominated by strong upper level trough ejecting across the central U.S. through Friday. Associated surface cold front will make steady progress esewd across the OH/MS River valleys but will likely slow as it enters our region Friday. This will occur as most of the energy with the upper system ejects northeast and mid/upper level flow begins to parallel the surface front. Deep ascent and increasing moisture ahead of this impulse will subsequently increase clouds with low clouds tonight possibly lingering in many areas tomorrow as Gulf moisture is pulled north-northwest. This will make high temperature forecast a bit tricky for Thursday. However models still suggest another mild day with highs reaching into the lower 80s for inland sites and a few degrees cooler on Friday with more clouds and increasing chance of showers from west to east. Although this system will likely support a considerable severe thunderstorm threat well to the northwest of our region, the potential for severe weather appears fairly low into the tri-state area Friday. Although an isolated storm could become marginally severe given the abundant moisture and modest deep layer shear, with SPC keeping low severe probabilities across the region. Regardless, system will likely bring showers and thunderstorms starting in the west Friday morning and spreading into the eastern areas by the late afternoon. && .LONG TERM [Saturday through Wednesday]... Long term looks a bit unsettled early in the period as a surface cold front stalls into northern/central FL. This could keep some showers around south central GA and the eastern Big Bend Saturday and possibly into Sunday. After a fairly cool day Saturday behind the front with highs in the lower 70s, temperatures will return to near normal (highs in the upper 70s/lower 80s) for Sunday and slowly warm into the middle part of next week. Another mid/upper level trough and associated surface front will approach the area around mid week and bring another shot at showers and thunderstorms by Wednesday. && .AVIATION... [Through 00z Friday] VFR conditions are expected to prevail for the first part of tonight but quickly fall off as low ceilings creep into KTLH, KVLD, and KABY around 09z. Confidence for wide spread fog tonight is low in the western portions of our CWA with the greatest chance for fog being in Valdosta. With winds not dying off overnight only light fog is expected in our eastern sites with low ceilings being the main concern. VFR conditions will resume by mid-morning and continue throughout the rest of the period. && .MARINE... South to southeasterly winds will increase tonight and tomorrow ahead of an approaching weather system, with winds switching to out of the west-northwest Friday into Saturday behind a cold front. Speeds may approach advisory criteria just ahead of the front and over western areas for several hours behind the front. This system will bring an increasing chance of showers and thunderstorms to the western legs early Friday and spread across the area during the day. Although western areas should clear Saturday, a chance of lingering showers should persist around the Big Bend possibly into Sunday. && .FIRE WEATHER... Ample low level moisture on Thursday will keep minimum humidities above critical levels. Abundant low-level moisture and rain are expected on Friday with a passing cold front precluding any concerns. In its wake, the airmass will dry out on Saturday but remain above critical levels and this trend will continue into midweek. && .HYDROLOGY... Flooding is not expected to be a concern through the forecast period, although a few sites will remain in `action stage`. We could see an additional 0.50-1.00 inch of rain with the cold front Friday and Saturday. However, this is not expected to result in any significant rise over the next several days. && .PRELIMINARY POINT TEMPS/POPS... Tallahassee 64 83 64 80 54 / 0 10 10 60 60 Panama City 67 80 67 74 53 / 0 10 10 80 50 Dothan 63 86 65 73 47 / 0 10 20 80 40 Albany 63 85 64 78 49 / 0 10 10 70 60 Valdosta 63 83 64 81 56 / 0 10 10 50 60 Cross City 63 85 65 82 60 / 0 10 10 30 50 Apalachicola 67 78 68 76 55 / 0 10 10 60 50 && .TAE WATCHES/WARNINGS/ADVISORIES... FL...None. GA...None. AL...None. GM...None. && $$ NEAR TERM...Gould SHORT TERM...Evans LONG TERM...Evans AVIATION...Harrigan/Hersey MARINE...Gould/Evans FIRE WEATHER...Block HYDROLOGY...Evans
AREA FORECAST DISCUSSION...UPDATED
NWS PEACHTREE CITY GA
212 PM EDT TUE APR 16 2013 .PREV DISCUSSION... /ISSUED 1147 AM EDT TUE APR 16 2013/ UPDATE... HAVE MADE SEVERAL TWEAKS TO THE GRIDS. MAIN CHANGES HAVE BEEN TO INCREASE DEWPOINTS AND POPS...ESPECIALLY FOR THIS AFTERNOON. ALL HI-RES MODELS INDICATING AN INCREASE IN CONVECTIVE COVERAGE BETWEEN 18-00Z. SURFACE DEWPOINTS ARE ACTUALLY QUITE A BIT HIGHER THAN FORECAST. LIMITING FACTOR WILL BE CAPE IN THE MIDLEVELS...AS NOTED ON THE 12Z KFFC SOUNDING WITH A WEAK WARM NOSE AT ABOUT 640MB. EVEN MODIFYING THIS WARM NOSE /DECREASE TO 1C INSTEAD OF 3C/ ONLY YIELDS ABOUT 500 J/KG SBCAPE. HOWEVER...WITH SUCH A STRONG SHORTWAVE PUSHING INTO THE AREA AS EVIDENT ON WATER VAPOR LOOPS...THE LIFTING MAY SERVE TO COOL THAT WARM NOSE FURTHER. KBMX HAS A HINT OF THE WARM NOSE AND KOHX DOES NOT SHOW IT...SO WITH THE WESTERLIES ALOFT ADVECTING THAT AIRMASS THIS WAY IT WILL BE A MATTER OF THESE COMPETING FACTORS. SO THAT SAID...HAVE INCREASED POPS FOR NOW TO CHANCE...THOUGH IF YOU BELIEVE THE HRRR POPS MAY NEED TO BE INCREASED SOME MORE FOR THIS AFTERNOON...AND INCREASED THUNDER WORDING TO CHANCE /SCATTERED/ AS WELL. NOT TOTALLY SOLD ON THE HIGHER COVERAGE THAT THE HRRR IS INDICATING BUT AT LEAST HAVE TRENDED IN THAT DIRECTION. UPDATED PRODUCTS WILL BE OUT SHORTLY. TDP PREV DISCUSSION... /ISSUED 735 AM EDT TUE APR 16 2013/ SHORT TERM /TODAY THROUGH WEDNESDAY/... WEAK UPPER-LEVEL RIDGING PERSISTS OVER THE REGION THROUGH WEDNESDAY. INFLUENCE OF THE RIDGE WILL LIKELY KEEP CHANCES FOR AFTERNOON CONVECTION AT A MINIMUM TODAY ALTHOUGH INSTABILITY IS SUFFICIENT FOR A MENTION OF A SLIGHT CHANCE OVER THE WESTERN THIRD TO HALF OF NORTH AND CENTRAL GEORGIA. YESTERDAY EVENINGS SOUNDING SHOWS SIGNIFICANT COOLING WOULD BE NEEDED IN THE 700-400MB LEVELS FOR ANY SIGNIFICANT SEVERE WEATHER THREAT...AND THAT DOES NOT APPEAR TO BE LIKELY TODAY. BY WEDNESDAY THE RIDGE AXIS IS SHIFTING EAST OF THE STATE ALLOWING FOR CHANCE POPS OVER THE WEST AND SLIGHT CHANCE POPS TO SPREAD EAST OVER THE REMAINDER OF THE FORECAST AREA. ALTHOUGH AN ISOLATED STRONG STORM OR TWO CANNOT BE RULED OUT...INSTABILITY IS EXPECTED TO REMAIN TOO MARGINAL FOR A MENTION OF SEVERE THUNDERSTORMS AT THIS TIME. 20 LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/... LONG TERM PERIOD BEGINS WITH DEVELOPING SOUTHERLY FLOW WHICH SHOULD ACT TO SHUNT MOISTURE AXIS NORTH OF THE AREA. WILL STILL CARRY RESIDUAL 20 POPS FOR THE NORTH INTO THE FIRST PART OF THE OVERNIGHT PERIOD BUT QUICKLY DISSIPATE AFTER 06Z THU. ANOTHER ROUND POSSIBLE THU BUT OVERALL TRENDS ARE FOR LESS DIURNAL COVERAGE GIVEN SLIGHTLY LESS MOISTURE AND CORRESPONDINGLY LESS INSTABILITY. MODELS STILL IN GOOD AGREEMENT WITH EXCELLENT RUN TO RUN CONSISTENCY WRT NEXT STORM SYSTEM WHICH LOOKS TO EJECT OUT OF THE CENTRAL PLAINS THURSDAY AND MOVE INTO THE MID MISSISSIPPI VALLEY THURSDAY NIGHT. TIMING FOR THE LOCAL AREA INDICATES BAND OF SHOWERS AND SCATTERED THUNDERSTORMS REACHING NW GEORGIA JUST PRIOR TO 12Z FRIDAY. INSTABILITY STILL LOOKS MARGINAL FOR THIS EVENT WITH ONLY A NARROW SLIVER OF 200J/KG TO 400J/KG SURFACE BASED CAPE TO WORK WITH FOR NORTHERN SECTIONS. SLIGHTLY MORE INSTABILITY TO THE SOUTH WITH THIS SYSTEM AND WILL HAVE INCREASED THUNDER CHANCES ROUGHLY FROM THE ATLANTA METRO SOUTHWARD. 850MB JET IS VERY IMPRESSIVE WITH THIS SYSTEM WITH NEARLY 90 KTS INDICATED FOR THE OHIO VALLEY. OUR AREA ONLY GETS THE SOUTHERN END OF THIS BUT STILL GOOD ENOUGH FOR 65 KTS FOR NW CORNER. INSTABILITY LOOKS TO BE AHEAD OF MAIN WIND CORE SO TIMING MAY NOT LINE UP FOR THIS ONE. REGARDLESS...925MB WINDS ARE 50KTS OVER THE LOCAL AREA WHICH SHOULD RESULT IN NEAR SEVERE WINDS EVEN WITH THE ABSENCE OF ROBUST CONVECTION. WILL BEGIN TO RAMP UP WORDING IN HWO. ONCE SYSTEM CLEARS...BENIGN BUT COLD CONDITIONS FOR THIS TIME OF YEAR WITH LOWS RETURNING TO THE 30S. DEESE && .AVIATION... 18Z UPDATE... VFR THIS AFTERNOON WITH SHRA OR POSSIBLE TSRA DEVELOPING MAINLY FOR THE METRO TAFS...THOUGH WITH SOME QUESTIONS ABOUT COVERAGE HAVE INCLUDED VCSH WITH A TEMPO TSRA. EXPECT THIS ACTIVITY TO DIMINISH AFTER 00Z TONIGHT. CIGS SHOULD DROP AGAIN AFTER 08-09Z IN THE MORNING...WITH SOME GUIDANCE HINTING AT IFR. HAVE INCLUDED LOW MVFR FOR NOW BUT THIS WILL NEED TO BE REEVALUATED. MVFR FOG LIKELY AT MOST SITES EXCEPT ATL AS WELL. EXPECT A LIFTING/CLEARING TREND LATE WEDNESDAY MORNING. INCLUDED PROB30 TSRA FOR ATL WEDNESDAY AFTERNOON. E TO SE WINDS GENERALLY 5-10KT THROUGH THE PERIOD EXCEPT LIGHTER OVERNIGHT. //ATL CONFIDENCE...18Z UPDATE... MEDIUM ON OCCURRENCE OF TSRA THIS AFTERNOON...LOW ON IMPACTS TO ATL. MEDIUM ON CIGS WEDNESDAY MORNING. HIGH ON ALL OTHER ELEMENTS. TDP && .PRELIMINARY POINT TEMPS/POPS... ATHENS 79 59 82 59 / 20 10 30 20 ATLANTA 78 63 81 62 / 40 20 30 20 BLAIRSVILLE 76 57 77 58 / 30 20 40 20 CARTERSVILLE 81 60 82 59 / 40 20 30 20 COLUMBUS 83 64 85 63 / 20 10 20 20 GAINESVILLE 78 61 80 61 / 30 20 30 20 MACON 82 59 83 58 / 20 5 20 10 ROME 81 60 82 60 / 40 20 30 20 PEACHTREE CITY 78 59 82 60 / 40 20 30 20 VIDALIA 81 62 83 62 / 5 0 10 10 && .FFC WATCHES/WARNINGS/ADVISORIES... NONE. && $$
AREA FORECAST DISCUSSION...UPDATED
NWS PEACHTREE CITY GA
1147 AM EDT TUE APR 16 2013 .UPDATE... HAVE MADE SEVERAL TWEAKS TO THE GRIDS. MAIN CHANGES HAVE BEEN TO INCREASE DEWPOINTS AND POPS...ESPECIALLY FOR THIS AFTERNOON. ALL HI-RES MODELS INDICATING AN INCREASE IN CONVECTIVE COVERAGE BETWEEN 18-00Z. SURFACE DEWPOINTS ARE ACTUALLY QUITE A BIT HIGHER THAN FORECAST. LIMITING FACTOR WILL BE CAPE IN THE MIDLEVELS...AS NOTED ON THE 12Z KFFC SOUNDING WITH A WEAK WARM NOSE AT ABOUT 640MB. EVEN MODIFYING THIS WARM NOSE /DECREASE TO 1C INSTEAD OF 3C/ ONLY YIELDS ABOUT 500 J/KG SBCAPE. HOWEVER...WITH SUCH A STRONG SHORTWAVE PUSHING INTO THE AREA AS EVIDENT ON WATER VAPOR LOOPS...THE LIFTING MAY SERVE TO COOL THAT WARM NOSE FURTHER. KBMX HAS A HINT OF THE WARM NOSE AND KOHX DOES NOT SHOW IT...SO WITH THE WESTERLIES ALOFT ADVECTING THAT AIRMASS THIS WAY IT WILL BE A MATTER OF THESE COMPETING FACTORS. SO THAT SAID...HAVE INCREASED POPS FOR NOW TO CHANCE...THOUGH IF YOU BELIEVE THE HRRR POPS MAY NEED TO BE INCREASED SOME MORE FOR THIS AFTERNOON...AND INCREASED THUNDER WORDING TO CHANCE /SCATTERED/ AS WELL. NOT TOTALLY SOLD ON THE HIGHER COVERAGE THAT THE HRRR IS INDICATING BUT AT LEAST HAVE TRENDED IN THAT DIRECTION. UPDATED PRODUCTS WILL BE OUT SHORTLY. TDP && .PREV DISCUSSION... /ISSUED 735 AM EDT TUE APR 16 2013/ SHORT TERM /TODAY THROUGH WEDNESDAY/... WEAK UPPER-LEVEL RIDGING PERSISTS OVER THE REGION THROUGH WEDNESDAY. INFLUENCE OF THE RIDGE WILL LIKELY KEEP CHANCES FOR AFTERNOON CONVECTION AT A MINIMUM TODAY ALTHOUGH INSTABILITY IS SUFFICIENT FOR A MENTION OF A SLIGHT CHANCE OVER THE WESTERN THIRD TO HALF OF NORTH AND CENTRAL GEORGIA. YESTERDAY EVENINGS SOUNDING SHOWS SIGNIFICANT COOLING WOULD BE NEEDED IN THE 700-400MB LEVELS FOR ANY SIGNIFICANT SEVERE WEATHER THREAT...AND THAT DOES NOT APPEAR TO BE LIKELY TODAY. BY WEDNESDAY THE RIDGE AXIS IS SHIFTING EAST OF THE STATE ALLOWING FOR CHANCE POPS OVER THE WEST AND SLIGHT CHANCE POPS TO SPREAD EAST OVER THE REMAINDER OF THE FORECAST AREA. ALTHOUGH AN ISOLATED STRONG STORM OR TWO CANNOT BE RULED OUT...INSTABILITY IS EXPECTED TO REMAIN TOO MARGINAL FOR A MENTION OF SEVERE THUNDERSTORMS AT THIS TIME. 20 LONG TERM /WEDNESDAY NIGHT THROUGH MONDAY/... LONG TERM PERIOD BEGINS WITH DEVELOPING SOUTHERLY FLOW WHICH SHOULD ACT TO SHUNT MOISTURE AXIS NORTH OF THE AREA. WILL STILL CARRY RESIDUAL 20 POPS FOR THE NORTH INTO THE FIRST PART OF THE OVERNIGHT PERIOD BUT QUICKLY DISSIPATE AFTER 06Z THU. ANOTHER ROUND POSSIBLE THU BUT OVERALL TRENDS ARE FOR LESS DIURNAL COVERAGE GIVEN SLIGHTLY LESS MOISTURE AND CORRESPONDINGLY LESS INSTABILITY. MODELS STILL IN GOOD AGREEMENT WITH EXCELLENT RUN TO RUN CONSISTENCY WRT NEXT STORM SYSTEM WHICH LOOKS TO EJECT OUT OF THE CENTRAL PLAINS THURSDAY AND MOVE INTO THE MID MISSISSIPPI VALLEY THURSDAY NIGHT. TIMING FOR THE LOCAL AREA INDICATES BAND OF SHOWERS AND SCATTERED THUNDERSTORMS REACHING NW GEORGIA JUST PRIOR TO 12Z FRIDAY. INSTABILITY STILL LOOKS MARGINAL FOR THIS EVENT WITH ONLY A NARROW SLIVER OF 200J/KG TO 400J/KG SURFACE BASED CAPE TO WORK WITH FOR NORTHERN SECTIONS. SLIGHTLY MORE INSTABILITY TO THE SOUTH WITH THIS SYSTEM AND WILL HAVE INCREASED THUNDER CHANCES ROUGHLY FROM THE ATLANTA METRO SOUTHWARD. 850MB JET IS VERY IMPRESSIVE WITH THIS SYSTEM WITH NEARLY 90 KTS INDICATED FOR THE OHIO VALLEY. OUR AREA ONLY GETS THE SOUTHERN END OF THIS BUT STILL GOOD ENOUGH FOR 65 KTS FOR NW CORNER. INSTABILITY LOOKS TO BE AHEAD OF MAIN WIND CORE SO TIMING MAY NOT LINE UP FOR THIS ONE. REGARDLESS...925MB WINDS ARE 50KTS OVER THE LOCAL AREA WHICH SHOULD RESULT IN NEAR SEVERE WINDS EVEN WITH THE ABSENCE OF ROBUST CONVECTION. WILL BEGIN TO RAMP UP WORDING IN HWO. ONCE SYSTEM CLEARS...BENIGN BUT COLD CONDITIONS FOR THIS TIME OF YEAR WITH LOWS RETURNING TO THE 30S. DEESE AVIATION... 12Z UPDATE... MAINLY IFR CONDITIONS PREVAILING ACROSS THE FORECAST AREA AT THIS TIME. I EXPECT IFR...WITH LOCAL LIFR...CEILINGS AND VISIBILITIES TO LAST THROUGH 14Z...IMPROVING TO MOSTLY MVFR CONDITIONS ACROSS THE AREA 14-19Z WITH VFR EXPECTED AFTER. ISOLATED SHOWERS AND THUNDERSTORMS ARE POSSIBLE ACROSS THE WESTERN HALF OF THE FORECAST AREA THIS AFTERNOON...BUT PROBABILITIES AT TAF SITES TOO LOW TO INCLUDE IN THE TAFS AT THIS TIME. WINDS WILL REMAIN EAST TO SOUTHEAST THROUGH THE FORECAST PERIOD. WINDS SPEEDS WILL REMAIN 6KT OR LESS THROUGH 14Z...INCREASING INTO THE 6-9KT RANGE THROUGH 22Z BEFORE DIMINISHING TO 6KT OR LESS AGAIN. //ATL CONFIDENCE...12Z UPDATE... MEDIUM CONFIDENCE ON TIMING OF CIGS/VIS TRENDS THIS MORNING. HIGH CONFIDENCE ON ALL OTHER ELEMENTS. 20 && .PRELIMINARY POINT TEMPS/POPS... ATHENS 79 59 80 60 / 20 10 30 20 ATLANTA 78 63 80 62 / 40 20 30 20 BLAIRSVILLE 76 57 78 59 / 30 20 30 20 CARTERSVILLE 81 59 81 60 / 40 20 30 20 COLUMBUS 83 64 83 63 / 20 10 20 20 GAINESVILLE 78 62 80 61 / 30 20 30 20 MACON 82 61 82 61 / 20 5 20 20 ROME 81 59 81 61 / 40 20 30 20 PEACHTREE CITY 78 58 81 58 / 40 20 30 20 VIDALIA 81 62 83 63 / 5 0 10 10 && .FFC WATCHES/WARNINGS/ADVISORIES... NONE. && $$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
935 PM CDT WED APR 17 2013 .DISCUSSION... 934 PM CDT EVENING/MESOSCALE UPDATE... HAVE CANCELLED REMAINING CONVECTIVE WATCHES...THOUGH FLOODING WILL CONTINUE TO BE A SIGNIFICANT ISSUE THROUGH THURSDAY AND BEYOND. WARM FRONT EXTENDS FROM LOW PRESSURE WAVE OVER WESTERN MISSOURI... NORTHEAST INTO CENTRAL ILLINOIS AND CENTRAL INDIANA AT 02Z. OUTFLOW FROM PERSISTENT ELEVATED THUNDERSTORMS ACROSS IA/NORTHERN IL/IN HAS CONTINUED TO SUPPRESS SURFACE WARM FRONT SOUTH OF THE CWA...AND WILL LIKELY CONTINUE TO DO SO OVERNIGHT BEFORE DEEPENING SURFACE LOW LIFTS FROM MISSOURI INTO NORTHWEST IL IN ASSOCIATION WITH SHORT WAVE LIFTING OUT OF BASE OF UPPER TROUGH OVER THE SOUTHERN PLAINS. UNFORTUNATELY...THIS WILL RESULT IN CONTINUED FORCED ASCENT ATOP CONVECTIVELY ENHANCED FRONTAL ZONE TONIGHT WITHIN A BROAD REGION OF PERSISTENT STRONG WARM/MOIST ADVECTION AHEAD OF DEEP UPPER TROUGH OVER THE PLAINS. ILX 00Z SOUNDING TELLS THE STORY WITH RESPECT TO THE DIMINISHED SEVERE THREAT WITH STRONG LOW LEVEL INVERSION NORTH OF FRONT PREVENTING NEAR SFC-BASED STORMS. RAP GUIDANCE CONTINUES TO DEPICT A GRADIENT IN THE MUCAPE FIELD INCREASING TO 500-1000 J/KG AS YOU MOVE FARTHER SOUTH OF I-80. WHILE EFFECTIVE BULK SHEAR IN EXCESS OF 60 KT WILL CONTINUE TO ALLOW SOME ORGANIZATION FOR ELEVATED CONVECTION NORTH OF WARM FRONT...THE THREAT OF SEVERE WEATHER SHOULD BE LIMITED TO MARGINAL HAIL WITH THE BETTER ORGANIZED STORMS. WHILE THE SEVERE THREAT INTO THE OVERNIGHT HOURS IS RATHER LOW... FLOODING THREAT CONTINUES TO BE SIGNIFICANT INTO THURSDAY. RADAR ESTIMATES AND OBSERVED RAINFALL REPORTS INDICATE THAT MOST AREAS HAVE SEEN UPWARDS OF 0.75 INCHES OF RAIN...WITH MANY AREAS BETWEEN 1.5 AND 2.0 INCHES AND PARTS OF NORTH CENTRAL ILLINOIS IN EXCESS OF 2.5 INCHES. ILX 00Z RAOB DEPICTS PWAT OF 1.38 INCHES...199 PERCENT OF NORMAL...AN INDICATION OF THE VERY MOIST AIR MASS. ADDITIONAL RAINFALL AMOUNTS IN THE 1-2 INCH RANGE ARE VERY LIKELY THROUGH THURSDAY...LIKELY LEADING TO EXTENSIVE FLOODING ON AREA STREAMS AND RIVERS. AERIAL FLOOD WARNINGS REMAIN IN EFFECT INTO MIDDAY THURSDAY...AND MANY RIVER FORECAST SITES ARE HEADED FOR MODERATE TO MAJOR FLOODING. RATZER && .PREV DISCUSSION... 342 PM CDT .SHORT TERM...THROUGH FRIDAY... HAZARDOUS WEATHER ISSUES FROM SEVERE THUNDERSTORMS TO EXCESSIVE RAINFALL TO TORNADIC POTENTIAL WILL IMPACT THE REGION THROUGH THURSDAY NIGHT. FOR THE REMAINDER OF THE AFTERNOON AND INTO THIS EVENING...AT 230PM CDT...STRONG THUNDERSTORMS EXTEND ALONG A LINE FROM NEAR WAUKEGAN...SOUTHWEST THROUGH OTTAWA. WEST OF THIS LINE...AN EXTENSIVE AREA OF OVERRUNNING PCPN WITH EMBEDDED THUNDER EXTENDED BACK THROUGH ERN IOWA AND MISSOURI. MUCH OF THE ACTIVITY OVER NRN IL HAS FORMED ALONG AN ELEVATED WARM FRONT...BUT A MORE SOLID LINE HAS DEVELOPED IN THE WARM SECTOR. EXPECT THAT THE THUNDERSTORMS WILL SAG SEWD THROUGH THE EVENING...BRINGING SHOWERS AND THUNDERSTORMS INTO EAST-CENTRAL ILLINOIS AND NORTHWESTERN INDIANA. WITH COPIOUS AMOUNTS OF MOISTURE STREAMING INTO THE REGION...THE STORMS HAVE BEEN VERY EFFICIENT RAIN PRODUCERS...WITH 0.81 INCHES OF RAIN MEASURED AT THE ROCKFORD AIRPORT BTWN 12-18Z THIS MORNING. STORMS HAVE ALSO BEEN MARGINALLY SEVERE WITH NUMEROUS REPORTS OF SMALL HAIL RECEIVED...AND A FEW REPORTS OF LARGER HAIL AS WELL. THIS WILL BE THE CONVECTIVE MODE FOR THE REMAINDER OF THE EVENING AND OVERNIGHT TONIGHT...WITH MODERATE TO HEAVY RAIN AND SMALL HAIL AND OCCASIONAL STRONG WINDS GUSTS. THE FLOODING AND SEVERE WEATHER POTENTIAL WILL RAMP UP EVEN FURTHER TOMORROW AS THE UPPER TROUGH MOVES OUT OVER THE CENTRAL PLAINS AND A SFC LOW DEEPENS. THE SFC LOW WILL SWING THROUGH THE SOUTH HIGH PLAINS EARLY THIS EVENING BEFORE TURNING NEWD...RIPPLING ALONG A QUASI-STATIONARY COLD FRONT AND WARM FRONT. BY THURSDAY MORNING...THE LOW WILL ELONGATE FROM NWRN IL THROUGH NWRN MO...WITH THE SFC WARM FRONT EXTENDING NEWD ACROSS CENTRAL LAKE MICHIGAN. THIS WILL PUT THE CWA FIRMLY IN THE WARM SECTOR. WITH A WIDE OPEN GLFMEX...DEEP LAYER MOISTURE WILL STREAM NWD INTO THE REGION...WITH PWATS EXCEEDING 1.5 INCHES FOR AN EXTENDED PERIOD OF TIME...LEADING TO THE POTENTIAL FOR SIGNIFICANT WIDESPREAD RIVER AND AREAL FLOODING. SEE THE HYDROLOGY SECTION FOR FURTHER DETAILS. THE SEVERE WEATHER MODE SHOULD FOCUS ON STRONG...DAMAGING WINDS AND POSSIBLE TORNADOES. THE LATEST SPC DAY 2 CONVECTIVE OUTLOOK HAS INCREASED THE AREA SOUTH OF A LINE FROM EVANSTON TO PONTIAC TO A MODERATE RISK...WITH THE REMAINDER OF THE AREA IN A SLIGHT RISK. INCREASING HEAT AND MOISTURE...TEMPERATURES REACHING INTO THE LOW TO MIDDLE 70S AND DEW POINTS IN THE LOW TO MIDDLE 60S IN THE WARM SECTOR...INSTABILITY WILL BE AMPLE. WHILE THE GENERAL CONVECTIVE MODE WILL BE LINEAR WITH SMALL LINES AND BOWS POSSIBLE...PRODUCING DAMAGING WINDS...THE MODEL GUIDANCE IS IN GOOD AGREEMENT ON A STRONG LOW LEVEL JET...WITH SWLY WINDS OF 55-65KT ACROSS THE REGION. WHILE SFC WINDS ARE GENERALLY PROGGED TO BE SOUTHERLY...THERE WILL BE OPPORTUNITY FOR SFC WINDS TO BACK A LITTLE MORE EAST OF SOUTH AS THE SFC LOW TRACKS THROUGH NWRN IL AND INTO SRN WI. GIVEN THE AMPLE INSTABILITY...COMBINED WITH CLOCKWISE TURNING HODOGRAPHS...DISCRETE SUPER CELLS MAY DEVELOP OUT IN THE WARM SECTOR AHEAD OF THE LINEAR CONVECTION...WHICH WOULD BRING THE TORNADIC POTENTIAL TO THE REGION. THE POTENTIAL FOR SEVERE WEATHER AND HEAVY RAINFALL WILL CONTINUE UNTIL THE ASSOCIATED COLD FRONT PUSHES THROUGH THE REGION...BRINGING IN MUCH COOLER AIR. THE GUIDANCE IS IN GOOD AGREEMENT ON PUSHING THE FRONT ACROSS THE AREA THURSDAY EVENING. AS THE SFC LOW PUSHES OFF TO THE NORTHEAST...THE UPPER TROUGH WILL ALSO CROSS THE AREA. WITH PLENTY OF RESIDUAL SFC MOISTURE AND COOLER AIR AND CYCLONIC CURVATURE ALOFT...SOME LINGERING INSTABILITY SHOWERS SHOULD PERSIST INTO FRIDAY. HIGHS ON FRIDAY SHOULD DROP BACK INTO THE MIDDLE TO UPPER 40S. KREIN .LONG TERM - SATURDAY THROUGH WEDNESDAY... SPRAWLING SURFACE HIGH PRESSURE TO BUILD INTO THE AREA SATURDAY BEHIND DEPARTING SURFACE LOW/UPPER LEVEL TROUGH. A RETURN TO UNSEASONABLY COOL TEMPS WITH A NEEDED BREAK IN PRECIPITATION WILL BE SHORT LIVED HOWEVER AS THE UPPER FLOW QUICKLY RETURNS SOUTHWESTERLY AS ANOTHER POWERFUL SHORTWAVE TROUGH DIGS INTO WESTERN NORTH AMERICA ON SUNDAY. THIS SHORTWAVE CARVES OUT A TROUGH ACROSS THE MOUNTAIN WEST SUNDAY NIGHT INTO MONDAY. A SERIES OF UPPER LEVEL SHORT WAVE TROUGHS WILL THEN RIPPLE NORTHEAST IN THE SW FLOW ALOFT. SPECIFIC FEATURES ARE POORLY RESOLVED BY MEDIUM RANGE MODELS BUT OVERALL TREND WILL BE A RETURN TO INCREASING MOISTURE AS GULF OPENS BACK UP AGAIN. MEDIUM RANGE MODELS ARE IN FAIRLY GOOD AGREEMENT IN CONCEPT IN SAGGING THE SURFACE FRONTAL BOUNDARY SOUTH ACROSS THE LOCAL AREA MONDAY NIGHT AND STALLING IT OUT TUESDAY SETTING THE STAGE FOR ANOTHER PROLONGED PERIOD OF WET WEATHER TUESDAY INTO WEDNESDAY AS RIPPLES OF LOW PRESSURE LIFT NORTHEAST ALONG THE BOUNDARY. EF && .HYDROLOGY... 350 PM CDT WITH SFC DEW POINTS EXPECTED TO REACH INTO THE LOWER TO MIDDLE 60S AND PWATS POSSIBLY REACHING AS HIGH AS 1.75 INCHES...ANY THUNDERSTORMS THAT DEVELOP WILL BE EFFICIENT RAIN PRODUCERS. BASED ON THE MATT BUNKERS PWAT CLIMATOLOGY...THESE VALUES APPROACH RECORD LEVELS. SO...FLOODING WILL BE A MAJOR CONCERN FOR THE ENTIRE CWA...WITH STORM TOTAL PCPN AMOUNTS OF 2-3 INCHES OVER THE SERN PORTIONS OF THE CWA...GENERALLY SOUTH OF I-80...AND 3-4 INCHES TO THE NORTH. LATEST LOCAL QPF WOULD SUGGEST AN AREA OF PCPN OF 4-5 INCHES IS POSSIBLE ALONG OVER NORTHERN ILLINOIS. THIS REPRESENTS AN INCREASE OVER PREVIOUS FORECASTS...BUT GIVEN THE RECORD LEVEL PWATS FOR AN EXTENDED PERIOD OF TIME...CONFIDENCE IS INCREASING FOR THIS SIGNIFICANT RAINFALL. WITH MANY RIVERS AND STREAMS ARE ALREADY NEAR OR ABOVE MINOR FLOOD STAGE...THIS AMOUNT OF RAIN WILL BRING ADDITIONAL RISES TO MODERATE AND MAJOR FLOOD LEVEL. IN ADDITION TO RIVER FLOODING...AREAL FLOODING OR RURAL...SUBURBAN AND URBAN AREAS IS LIKELY...WITH LOW LYING ROADS AND VIADUCTS FLOODING...AS WELL AS...ROADSIDE DRAINAGE DITCHES AND DRAINAGE PONDS EXCEEDING CAPACITY. AREAS NOT SEEING FLOODING WILL AT LEAST SEE AREAS OF STANDING OR PONDING WATER ON ROADS. KREIN && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 00Z... * WIDESPREAD LIGHT TO OCCASIONAL MODERATE RAIN FIRST PART OF EVENING WITH A FEW EMBEDDED TS AND LOCALIZED HEAVY RAIN. * WIDESPREAD RAIN CONTINUES LATE EVENING INTO OVERNIGHT WITH MORE NUMEROUS TS AND MORE WIDESPREAD AREAS OF +RA. * WIDESPREAD MVFR WITH AREAS IFR TO START OUT THE EVE THEN IFR TO BECOME PREVAILING AS RA AND TS COVERAGE INCREASES FOR LATER EVE AND OVERNIGHT. * ENE SFC WINDS TO GRADUALLY BECOME SSE AND BECOMING MODERATELY GUSTY BY DAYBREAK AND INCREASINGLY GUSTY FROM SSE-SSW WINDS DURING THE DAY. TRS //DISCUSSION...UPDATED 00Z... MULTIPLE SHORT WAVES CONTINUE/TO CONTINUE TO MOVE FROM THE SOUTHERN PLAINS NORTHEASTWARD ACROSS THE MID MO AND MID AND UPPER MS VALLEYS TO THE WESTERN GREAT LAKES TONIGHT AND THU AS THE UPPER UPPER TROUGH CONTINUE TO MOVE E FROM THE ROCKIES AND OVER THE PLAINS. THESE MULTIPLE SMALL TO MEDIUM DISTURBANCES ARE EXPECTED TO CONTINUE TO PERIODICALLY CAUSE INCREASED RA COVERAGE AND NUMBER OF TS OVER THE CHI TERMINALS ALONG AND N OF THE SURFACE BOUNDARY TONIGHT AS THEY LIFT NE TOWARD AN THEN OVER THE LOCAL AREA. PROFILER...VAD AND RAOB WIND MEASUREMENTS CONFIRM INCREASING S TO SW FLOW ABOVE THE INCREASINGLY SHALLOW BOUNDARY LAYER WITH SPEED OF 50 TO 60KT WITHIN 1 TO 2K FT OF SURFACE BY LATE OVERNIGHT TONIGHT AND HAVE CONTINUED LLWS FORECASTS DURING THE NIGHT IN 00Z SET OF TAFORS. MVFR AND AREAS OF IFR CEILINGS EXPECTED TO PERSIST N OF THE SURFACE FRONT TIL IT LIFTS NORTHWARD AND ACROSS THE LOCAL TERMINALS DURING THE PREDAWN TO EARLY MORNING HOURS OF THU. WITH THE WARM FRONT TO THE N OF THE LOCAL AREA BY EARLY THU MORNING THE STRONGEST FORCING RESULTING FROM THE VERY STRONG LOW LEVEL WAA AND CONVERGENCE IS ANTICIPATED TO SHIFT GENERALLY TO THE N OF THE LOCAL TERMINALS THOUGH ACROSS THE LOCAL AREA S OF THE BOUNDARY SURFACE BASED INSTABILITY WILL BE INCREASING DURING THU SO CANNOT RULE OUT SCATTERED TSRA FROM MID AFTERNOON INTO EARLY EVENING. TRS //ORD AND MDW CONFIDENCE...UPDATED 00Z... * HIGH CONFIDENCE IN FORECAST WIND TRENDS. * MODERATE CONFIDENCE IN TIMING OF BETTER TIME FRAMES FOR MORE WIDESPREAD RA AND +RA/+TSRA. * LOW CONFIDENCE IN ONSET AND DURATION OF IFR CONDITIONS. TRS //OUTLOOK FOR ORD/MDW FOR 12Z FRIDAY-12Z WEDNESDAY...UPDATED 00Z... FRIDAY...VFR...CHANCE SHRA WITH LOCAL MVFR. SATURDAY...VFR...LAKE BREEZE DEVELOPING AND REACHING CHI TERMINALS EARLY-MID AFTERNOON. SUNDAY...VFR...SLIGHT CHANCE SHRA. MONDAY...VFR...CHANCE SHOWERS. TUESDAY...MVFR LOWERING TO IFR....CHANCE OF SHOWERS. TRS && .MARINE... 420 PM CDT A PAIR OF LOW PRESSURE CENTERS OVER NORTHERN MISSOURI AND THE TEXAS PANHANDLE WILL MOVE NORTHEAST TONIGHT AND THURSDAY AND OVERSPREAD THE GREAT LAKES AREA. A BRIEF PERIOD OF OCCASIONALLY GALE FORCE GUSTS WILL OCCUR ACROSS SOUTHERN LAKE MICHIGAN THURSDAY AS THE SURFACE PRESSURE GRADIENT INTENSIFIES SOUTH OF THE ELONGATED LOW PRESSURE AREA FROM THE SAULT TO GREEN BAY. AS LOW PRESSURE LOCATES NEAR MILWAUKEE THURSDAY EVENING AND THEN MOVES NORTHEAST TO THE STRAITS OF MACKINAC BY DAYBREAK FRIDAY... A POWERFUL COLD FRONT WILL SURGE EAST ACROSS THE LAKE WITH WINDS INCREASING RAPIDLY BEHIND THE FRONT DURING THE PREDAWN HOURS FRIDAY. WINDS WILL RAPIDLY REACH GALE FORCE TO 45 KTS FRIDAY WITH A DIMINISHING TREND BEGINNING AFTER DARK FRIDAY EVENING. SURFACE HIGH PRESSURE WILL BUILD INTO THE AREA SATURDAY BRINGING A PERIOD OF LIGHT WINDS LASTING ONLY UNTIL DAYBREAK SUNDAY WHEN SOUTHERLY FLOW WILL AGAIN INCREASE AHEAD OF AN APPROACHING FRONTAL BOUNDARY. ED F && .LOT WATCHES/WARNINGS/ADVISORIES... IL...FLOOD WATCH...ILZ003-ILZ004-ILZ005-ILZ006-ILZ008-ILZ010-ILZ011- ILZ012-ILZ013-ILZ014-ILZ019-ILZ020-ILZ021-ILZ022-ILZ023- ILZ032-ILZ033-ILZ039 UNTIL 7 AM FRIDAY. IN...FLOOD WATCH...INZ001-INZ002-INZ010-INZ011-INZ019 UNTIL 7 AM FRIDAY. LM...GALE WATCH...LMZ080-LMZ261-LMZ362-LMZ364-LMZ366-LMZ563-LMZ565- LMZ567-LMZ669-LMZ671-LMZ673-LMZ675-LMZ777-LMZ779-LMZ868- LMZ870-LMZ872-LMZ874-LMZ876-LMZ878...7 AM FRIDAY TO 4 AM SATURDAY. GALE WARNING...LMZ740-LMZ741-LMZ742...7 AM THURSDAY TO 7 PM THURSDAY. SMALL CRAFT ADVISORY...NEARSHORE WATERS UNTIL 7 AM THURSDAY. GALE WARNING...LMZ743-LMZ744-LMZ745...7 AM THURSDAY TO 10 PM THURSDAY. && $$
AREA FORECAST DISCUSSION
NWS LINCOLN IL
1228 PM CDT TUE APR 16 2013 .DISCUSSION... ISSUED 1030 AM CDT TUE APR 16 2013 COLD FRONT HAS PUSHED JUST SOUTH OF OUR CWA...BUT WAS CLOSE ENOUGH TO LAWRENCEVILLE THAT TEMPERATURES THERE ARE STILL IN THE MID 60S. MOSTLY SEEING 40S ELSEWHERE WITH SOME LOWER 50S. ELEVATED CONVECTION NORTH OF THE BOUNDARY HAS BEEN INCREASING OVER CENTRAL ILLINOIS AS IT MOVES OUT OF MISSOURI...AND COVERED MOST OF THE CWA AT 1030 AM EXCEPT FOR THE FAR NORTHWEST AND FAR SOUTHEAST. LATEST RAP MODEL SHOWING THE SCATTERED CONVECTION CONTINUING ACROSS MUCH OF THE CWA INTO THIS AFTERNOON...WITH LESS COVERAGE NORTHWEST OF THE ILLINOIS RIVER. HAVE SENT OUT SOME ZONE/GRID UPDATES TO INCREASE THE RAIN CHANCES TODAY...WITH SOME MINOR ADJUSTMENTS TO TEMPERATURES REQUIRED AS WELL. GEELHART && .HYDROLOGY... ISSUED 1030 AM CDT TUE APR 16 2013 EARLY LOOK AT 12Z MODEL RUNS CONTINUE TO SUPPORT AN INCREASING POOL OF MOISTURE INTO ILLINOIS ON WEDNESDAY...WITH PRECIPITABLE WATER VALUES UP TO AROUND 1.5 TO 1.6 INCHES BY LATE WEDNESDAY AFTERNOON...WHICH IS ABOUT 2 STANDARD DEVIATIONS ABOVE NORMAL. BULK OF THE HEAVIEST RAIN EXPECTED WEDNESDAY NIGHT THROUGH THURSDAY NIGHT. LATEST QPF FORECAST SHOWS OVER 3 INCHES ACROSS A LARGE PART OF THE FORECAST AREA THROUGH FRIDAY...WITH 2-3 INCHES ACROSS ABOUT THE SOUTHEAST THIRD. PROBABILITY FORECASTS FROM THE WEATHER PREDICTION CENTER SHOW A 50-60 PERCENT CHANCE OF RECEIVING AT LEAST 2.5 INCHES OF RAIN FROM WEDNESDAY EVENING THROUGH THURSDAY EVENING. CURRENTLY ONLY THE ILLINOIS RIVER AT HAVANA AND BEARDSTOWN ARE IN FLOOD...BUT MORE FLOODING IS EXPECTED ACROSS MANY RIVERS. STANDARD RIVER FORECASTS ONLY ACCOUNT FOR 24-HOUR QPF...BUT RFC CONTINGENCY FORECASTS BASED ON 72-HOUR QPF SHOW POTENTIAL FOR MODERATE OR MAJOR FLOODING IN SOME CASES. HAVE SENT OUT A HYDROLOGIC OUTLOOK TO ADDRESS THE HEAVY RAIN POTENTIAL...WHILE REMAINING MODEL GUIDANCE IS DIGESTED TO DETERMINE THE POTENTIAL FOR ANY FLOOD WATCHES WITH THE AFTERNOON FORECAST PACKAGE. GEELHART && .AVIATION... ISSUED 1224 PM CDT TUE APR 16 2013 BAND OF THUNDERSTORMS WILL CONTINUE TO AFFECT KCMI AND KDEC FOR ANOTHER HOUR OR TWO...WITH MVFR CEILINGS/VISIBILITIES. GENERAL TREND OTHERWISE WILL BE FOR SCATTERED SHOWERS TO CONTINUE THIS AFTERNOON...WITH CEILINGS GENERALLY VFR FOR A TIME. HOWEVER... ADDITIONAL CONVECTIVE DEVELOPMENT WILL BRING MVFR CONDITIONS AGAIN THIS EVENING. BASED ON SOUNDINGS...CEILINGS AFTER 06Z MAY FALL TO AROUND 1000 FEET OR SO...WHICH WILL LINGER A GOOD PART OF WEDNESDAY MORNING. HOWEVER...A WARM FRONT WILL LIFT NORTHWARD ACROSS THE TAF SITES TOWARD LATE MORNING...RAPIDLY LIFTING CEILINGS BACK INTO VFR RANGE. GEELHART && .PREV DISCUSSION... ISSUED 330 AM CDT TUE APR 16 2013 VERY UNSETTLED WEATHER PATTERN TO OCCUR THROUGH FRIDAY ACROSS CENTRAL AND SE IL WITH PERIODS OF SHOWERS AND THUNDERSTORM GIVING 2-4 INCHES OF RAIN BY FRIDAY WITH THE HEAVIEST AMOUNTS FROM I-55 NW. SPC ALSO CONTINUES SLIGHT RISK OF SEVERE STORMS ACROSS AREAS WEST OF I-57 WED NIGHT AND ACROSS MUCH OF REGION THU/THU EVENING. LIKE YESTERDAYS MODEL RUNS...THE 00Z MODEL SUITE TODAY CONTINUES SLOWER TREND WITH POTENT COLD FRONT MOVING EASTWARD ACROSS IL THU AFTERNOON/EVENING. SHORT TERM...TODAY THROUGH FRIDAY MCS FROM CENTRAL MO NE ACROSS CENTRAL IL INTO NW INDIANA HAS GRADUALLY BEEN WEAKENING THE PAST HOUR OR SO. A BROKEN LINE OF THUNDERSTORMS WITH HEAVY RAINS WAS ALONG SE EDGE OF THIS MCS FROM TAYLORVILLE AND SHELBYVILLE TO TUSCOLA AND CHRISMAN. HAD A FEW REPORTS OF HAIL BETWEEN MIDNIGHT AND 1 AM OVER PARTS OF SANGAMON AND LOGAN COUNTIES. COLD FRONT HAD SAGGED SLOWLY INTO SE IL...SE OF I-70 EARLY THIS MORNING BEING PULLED SE BY MCS AND 1012 MB LOW PRESSURE NEAR INDY. COLD FRONT EXTENDED SW TO A 1000 MB LOW PRESSURE OVER EASTERN NM. BROAD SW UPPER LEVEL FLOW OVER THE COUNTRY HAS BEEN SLOWLY DOWN THE SE PROGRESSION OF THIS COLD FRONT. RADAR ESTIMATED 1.5-2.5 INCHES OF RAIN ALONG AND JUST SE OF A RUSHVILLE TO BLOOMINGTON LINE. CONVECTION TO CONTINUE TO WEAKEN DURING THE MORNING WITH AS LOW LEVEL JET THAT PEAKED AROUND 40 KTS WEAKENS. BEST CHANCES OF SHOWERS AND THUNDERSTORMS TODAY SHIFTS INTO SE IL CLOSER TO FRONTAL BOUNDARY WHICH CONTINUES TO SLOWLY SAG SOUTHWARD TODAY... WHILE DRIER AND COOLER TO THE NORTH. SCATTERED SHOWERS AND THUNDERSTORMS POSSIBLE THIS AFTERNOON ESPECIALLY FROM I-72 SOUTH. HIGHS TODAY RANGE FROM THE MID 50S OVER THE IL RIVER VALLEY FROM I-55 NW TO THE UPPER 60S TO NEAR 70F IN FAR SE IL ALONG HIGHWAY 50. INCREASING LOW LEVEL JET TO INCREASE CHANCES OF SHOWERS AND THUNDERSTORMS TONIGHT ESPECIALLY OVERNIGHT WHEN SPC HAS SLIGHT CHANCE OF SEVERE OVER SE IL AND SW OF SPRINGFIELD. MAINLY A HAIL THREAT SW OF SPRINGFIELD WHILE HAIL AND WIND IN FAR SE IL NEAR HIGHWAY 50. FRONTAL BOUNDARY TO BEGIN TO LIFT BACK NORTHWARD OVER CENTRAL IL WED WITH SHOWERS AND THUNDERSTORMS LIKELY ESPECIALLY NW AREAS. HIGHS RANGE FROM THE MID 60S NW OF THE IL RIVER TO THE UPPER 70S AND LOWER 80S ACROSS SE IL. BEST CHANCES OF SHOWERS AND THUNDERSTORMS OVER THE AREAS WED NIGHT THROUGH THU NIGHT AS STRONG COLD FRONT MOVES EASTWARD OVER IL THU AFTERNOON/EVENING. SPC HAS MUCH OF AREA IN A SLIGHT RISK OF SEVERE STORMS DURING THIS TIME FOR DAMAGING WIND GUSTS WITH A SQUALL LINE AND LARGE HAIL ALSO A RISK. HEAVIEST RAINS TO OCCUR WED NIGHT THROUGH THU NIGHT WITH 2-4 INCHES POSSIBLE AND HEAVIEST OVER THE IL RIVER VALLEY. HIGHS THU TRICKING DEPENDING ON HOW FAST COLD FRONT MOVES INTO AREA... BUT UPPER 70S AND LOWER 80S POSSIBLE OVER EASTERN IL ESPECIALLY NEAR THE WABASH RIVER WHILE TEMPS EXPECTED TO FALL OVER THE IL RIVER VALLEY THU AFTERNOON. COLD FRONT PASSES EAST OF IL FRI BUT STRONG UPPER LEVEL TROF MOVING INTO AREA TO CONTINUE LOW CLOUDS ALONG WITH A GOOD CHANCE OF SHOWERS. COULD BE COLD ENOUGH FOR A CHANCE OF LIGHT SNOW SHOWERS TOO NORTH OF PEORIA FRIDAY MORNING THOUGH BEST CHANCES OF SNOW SHOWERS IS FURTHER NW OVER NW IL. HIGHS FRI ONLY 45-50 OVER CENTRAL IL AND LOWER 50S IN SE IL. LONG TERM...FRIDAY NIGHT THROUGH TUESDAY CANADIAN HIGH PRESSURE TO BUILD INTO IL SAT AND BRING DRY BUT COOL WEATHER FRIDAY NIGHT THRU SAT NIGHT. LOWS FRIDAY NIGHT IN THE LOWER 30S CENTRAL IL AND MID 30S SE IL. HIGHS SAT IN THE LOW TO MID 50S. LOWS SAT NIGHT IN THE MID TO UPPER 30S. CANADIAN HIGH DRIFTING INTO THE EASTERN GREAT LAKES REGION SUNDAY TO ALLOW TEMPS TO MODIFY INTO THE UPPER 50S AND LOWER 60S SUNDAY AND INTO THE LOW TO MID 60S MONDAY. A COLD FRONT APPROACHING THE MS VALLEY MONDAY TO GIVE CENTRAL AND WESTERN IL CHANCES OF SHOWERS AND ISOLATED THUNDERSTORMS WHICH CONTINUES ACROSS AREA MONDAY NIGHT/TUE AS COLD FRONT SWEEPS THROUGH BRINGING COOLER AIR TUE ON BREEZY NW WINDS. ECMWF AND GFS MODELS FAIRLY SIMILAR WITH THIS WEATHER SYSTEM EARLY NEXT WEEK. 07 && .ILX WATCHES/WARNINGS/ADVISORIES... NONE. && $$
AREA FORECAST DISCUSSION
NWS LINCOLN IL
1034 AM CDT TUE APR 16 2013 .DISCUSSION... ISSUED 1030 AM CDT TUE APR 16 2013 COLD FRONT HAS PUSHED JUST SOUTH OF OUR CWA...BUT WAS CLOSE ENOUGH TO LAWRENCEVILLE THAT TEMPERATURES THERE ARE STILL IN THE MID 60S. MOSTLY SEEING 40S ELSEWHERE WITH SOME LOWER 50S. ELEVATED CONVECTION NORTH OF THE BOUNDARY HAS BEEN INCREASING OVER CENTRAL ILLINOIS AS IT MOVES OUT OF MISSOURI...AND COVERED MOST OF THE CWA AT 1030 AM EXCEPT FOR THE FAR NORTHWEST AND FAR SOUTHEAST. LATEST RAP MODEL SHOWING THE SCATTERED CONVECTION CONTINUING ACROSS MUCH OF THE CWA INTO THIS AFTERNOON...WITH LESS COVERAGE NORTHWEST OF THE ILLINOIS RIVER. HAVE SENT OUT SOME ZONE/GRID UPDATES TO INCREASE THE RAIN CHANCES TODAY...WITH SOME MINOR ADJUSTMENTS TO TEMPERATURES REQUIRED AS WELL. GEELHART && .HYDROLOGY... ISSUED 1030 AM CDT TUE APR 16 2013 EARLY LOOK AT 12Z MODEL RUNS CONTINUE TO SUPPORT AN INCREASING POOL OF MOISTURE INTO ILLINOIS ON WEDNESDAY...WITH PRECIPITABLE WATER VALUES UP TO AROUND 1.5 TO 1.6 INCHES BY LATE WEDNESDAY AFTERNOON...WHICH IS ABOUT 2 STANDARD DEVIATIONS ABOVE NORMAL. BULK OF THE HEAVIEST RAIN EXPECTED WEDNESDAY NIGHT THROUGH THURSDAY NIGHT. LATEST QPF FORECAST SHOWS OVER 3 INCHES ACROSS A LARGE PART OF THE FORECAST AREA THROUGH FRIDAY...WITH 2-3 INCHES ACROSS ABOUT THE SOUTHEAST THIRD. PROBABILITY FORECASTS FROM THE WEATHER PREDICTION CENTER SHOW A 50-60 PERCENT CHANCE OF RECEIVING AT LEAST 2.5 INCHES OF RAIN FROM WEDNESDAY EVENING THROUGH THURSDAY EVENING. CURRENTLY ONLY THE ILLINOIS RIVER AT HAVANA AND BEARDSTOWN ARE IN FLOOD...BUT MORE FLOODING IS EXPECTED ACROSS MANY RIVERS. STANDARD RIVER FORECASTS ONLY ACCOUNT FOR 24-HOUR QPF...BUT RFC CONTINGENCY FORECASTS BASED ON 72-HOUR QPF SHOW POTENTIAL FOR MODERATE OR MAJOR FLOODING IN SOME CASES. HAVE SENT OUT A HYDROLOGIC OUTLOOK TO ADDRESS THE HEAVY RAIN POTENTIAL...WHILE REMAINING MODEL GUIDANCE IS DIGESTED TO DETERMINE THE POTENTIAL FOR ANY FLOOD WATCHES WITH THE AFTERNOON FORECAST PACKAGE. GEELHART && .AVIATION... ISSUED 645 AM CDT TUE APR 16 2013 CLOUDS REMAIN OVER THE REGION AND WILL LIKELY STAY THAT WAY THROUGH THE PERIOD. MAIN QUESTION IS WHAT WILL THE CIG HEIGHTS BE THROUGH THE PERIOD AND WHEN WILL PCPN RETURN. SPI/PIA/BMI WILL ALL BE VFR AT START AND THROUGH MOST OF THE PERIOD...UNTIL PCPN MOVES BACK OVER THE SITES LATE THIS EVENING AND INTO THE OVERNIGHT HOURS. FOR DEC...BASED ON SATELLITE TRENDS BELIEVE DEC WILL START AS VFR...BUT LOWER MVFR CIGS MAY LINGER IN THE AREA FOR COUPLE OF HOURS...SO HAVE 2HR TEMPO GROUP FIRST COUPLE OF HOURS THIS MORNING. BASED ON SATELLITE TRENDS...CMI SHOULD START WITH MVFR CIGS...BUT IFR CIGS ARE THERE NOW SO HAVE A ONE HOUR TEMPO GROUP FOR IFR AND THEN 2HR TEMPO GROUP FOR MVFR CIGS...SINCE VFR CIGS SHOULD BE AT THE SITE IN NEXT COUPLE OF HOURS. THEN DEC AND CMI SHOULD BE VFR THROUGH THE DAY...AND LIKE THE OTHER SITES...NOT BECOME MVFR TIL PCPN MOVES BACK INTO THE AREA. UNSURE HOW LOW CIGS WILL GET LATER TONIGHT WITH PCPN...BUT WILL START WITH MVFR...BUT COULD GET LOWER. WINDS WILL BE NORTHERLY TO START TODAY AND THEN GRADUALLY SHIFT TO NORTHEAST-EAST BY THIS EVENING. WIND SPEEDS WILL BE AROUND 10KTS OR LESS THROUGH THE PERIOD. AUTEN && .PREV DISCUSSION... ISSUED 330 AM CDT TUE APR 16 2013 VERY UNSETTLED WEATHER PATTERN TO OCCUR THROUGH FRIDAY ACROSS CENTRAL AND SE IL WITH PERIODS OF SHOWERS AND THUNDERSTORM GIVING 2-4 INCHES OF RAIN BY FRIDAY WITH THE HEAVIEST AMOUNTS FROM I-55 NW. SPC ALSO CONTINUES SLIGHT RISK OF SEVERE STORMS ACROSS AREAS WEST OF I-57 WED NIGHT AND ACROSS MUCH OF REGION THU/THU EVENING. LIKE YESTERDAYS MODEL RUNS...THE 00Z MODEL SUITE TODAY CONTINUES SLOWER TREND WITH POTENT COLD FRONT MOVING EASTWARD ACROSS IL THU AFTERNOON/EVENING. SHORT TERM...TODAY THROUGH FRIDAY MCS FROM CENTRAL MO NE ACROSS CENTRAL IL INTO NW INDIANA HAS GRADUALLY BEEN WEAKENING THE PAST HOUR OR SO. A BROKEN LINE OF THUNDERSTORMS WITH HEAVY RAINS WAS ALONG SE EDGE OF THIS MCS FROM TAYLORVILLE AND SHELBYVILLE TO TUSCOLA AND CHRISMAN. HAD A FEW REPORTS OF HAIL BETWEEN MIDNIGHT AND 1 AM OVER PARTS OF SANGAMON AND LOGAN COUNTIES. COLD FRONT HAD SAGGED SLOWLY INTO SE IL...SE OF I-70 EARLY THIS MORNING BEING PULLED SE BY MCS AND 1012 MB LOW PRESSURE NEAR INDY. COLD FRONT EXTENDED SW TO A 1000 MB LOW PRESSURE OVER EASTERN NM. BROAD SW UPPER LEVEL FLOW OVER THE COUNTRY HAS BEEN SLOWLY DOWN THE SE PROGRESSION OF THIS COLD FRONT. RADAR ESTIMATED 1.5-2.5 INCHES OF RAIN ALONG AND JUST SE OF A RUSHVILLE TO BLOOMINGTON LINE. CONVECTION TO CONTINUE TO WEAKEN DURING THE MORNING WITH AS LOW LEVEL JET THAT PEAKED AROUND 40 KTS WEAKENS. BEST CHANCES OF SHOWERS AND THUNDERSTORMS TODAY SHIFTS INTO SE IL CLOSER TO FRONTAL BOUNDARY WHICH CONTINUES TO SLOWLY SAG SOUTHWARD TODAY... WHILE DRIER AND COOLER TO THE NORTH. SCATTERED SHOWERS AND THUNDERSTORMS POSSIBLE THIS AFTERNOON ESPECIALLY FROM I-72 SOUTH. HIGHS TODAY RANGE FROM THE MID 50S OVER THE IL RIVER VALLEY FROM I-55 NW TO THE UPPER 60S TO NEAR 70F IN FAR SE IL ALONG HIGHWAY 50. INCREASING LOW LEVEL JET TO INCREASE CHANCES OF SHOWERS AND THUNDERSTORMS TONIGHT ESPECIALLY OVERNIGHT WHEN SPC HAS SLIGHT CHANCE OF SEVERE OVER SE IL AND SW OF SPRINGFIELD. MAINLY A HAIL THREAT SW OF SPRINGFIELD WHILE HAIL AND WIND IN FAR SE IL NEAR HIGHWAY 50. FRONTAL BOUNDARY TO BEGIN TO LIFT BACK NORTHWARD OVER CENTRAL IL WED WITH SHOWERS AND THUNDERSTORMS LIKELY ESPECIALLY NW AREAS. HIGHS RANGE FROM THE MID 60S NW OF THE IL RIVER TO THE UPPER 70S AND LOWER 80S ACROSS SE IL. BEST CHANCES OF SHOWERS AND THUNDERSTORMS OVER THE AREAS WED NIGHT THROUGH THU NIGHT AS STRONG COLD FRONT MOVES EASTWARD OVER IL THU AFTERNOON/EVENING. SPC HAS MUCH OF AREA IN A SLIGHT RISK OF SEVERE STORMS DURING THIS TIME FOR DAMAGING WIND GUSTS WITH A SQUALL LINE AND LARGE HAIL ALSO A RISK. HEAVIEST RAINS TO OCCUR WED NIGHT THROUGH THU NIGHT WITH 2-4 INCHES POSSIBLE AND HEAVIEST OVER THE IL RIVER VALLEY. HIGHS THU TRICKING DEPENDING ON HOW FAST COLD FRONT MOVES INTO AREA... BUT UPPER 70S AND LOWER 80S POSSIBLE OVER EASTERN IL ESPECIALLY NEAR THE WABASH RIVER WHILE TEMPS EXPECTED TO FALL OVER THE IL RIVER VALLEY THU AFTERNOON. COLD FRONT PASSES EAST OF IL FRI BUT STRONG UPPER LEVEL TROF MOVING INTO AREA TO CONTINUE LOW CLOUDS ALONG WITH A GOOD CHANCE OF SHOWERS. COULD BE COLD ENOUGH FOR A CHANCE OF LIGHT SNOW SHOWERS TOO NORTH OF PEORIA FRIDAY MORNING THOUGH BEST CHANCES OF SNOW SHOWERS IS FURTHER NW OVER NW IL. HIGHS FRI ONLY 45-50 OVER CENTRAL IL AND LOWER 50S IN SE IL. LONG TERM...FRIDAY NIGHT THROUGH TUESDAY CANADIAN HIGH PRESSURE TO BUILD INTO IL SAT AND BRING DRY BUT COOL WEATHER FRIDAY NIGHT THRU SAT NIGHT. LOWS FRIDAY NIGHT IN THE LOWER 30S CENTRAL IL AND MID 30S SE IL. HIGHS SAT IN THE LOW TO MID 50S. LOWS SAT NIGHT IN THE MID TO UPPER 30S. CANADIAN HIGH DRIFTING INTO THE EASTERN GREAT LAKES REGION SUNDAY TO ALLOW TEMPS TO MODIFY INTO THE UPPER 50S AND LOWER 60S SUNDAY AND INTO THE LOW TO MID 60S MONDAY. A COLD FRONT APPROACHING THE MS VALLEY MONDAY TO GIVE CENTRAL AND WESTERN IL CHANCES OF SHOWERS AND ISOLATED THUNDERSTORMS WHICH CONTINUES ACROSS AREA MONDAY NIGHT/TUE AS COLD FRONT SWEEPS THROUGH BRINGING COOLER AIR TUE ON BREEZY NW WINDS. ECMWF AND GFS MODELS FAIRLY SIMILAR WITH THIS WEATHER SYSTEM EARLY NEXT WEEK. 07 && .ILX WATCHES/WARNINGS/ADVISORIES... NONE. && $$
AREA FORECAST DISCUSSION
NWS WICHITA KS
712 PM CDT WED APR 17 2013 .UPDATE... ISSUED AT 711 PM CDT WED APR 17 2013 THUNDERSTORMS HAVE YET TO FORM ALONG THE SURFACE FRONT OVER SOUTHEAST KS. INSPECTION OF MODIFIED RUC SOUNDINGS INDICATE POOR LAPSE RATES/RELATIVELY WARM TEMPERATURES THROUGH 700-600MB. SO DESPITE GOOD CONVERGENCE ALONG THE SURFACE FRONT...NEAR-SURFACE COLD AIR IS LIKELY TOO SHALLOW TO BREAK THROUGH THE WARMER MID-LEVEL TEMPERATURES...WITH ONLY WEAK BUOYANCY FROM THE SURFACE-700/600MB. CONSEQUENTLY...FEEL THE HIGH- END SEVERE WEATHER THREAT INCLUDING TORNADOES...DAMAGING WINDS AND VERY LARGE HAIL IS WANING...ALTHOUGH STILL CANNOT RULE OUT SEVERE ACTIVITY EITHER DEVELOPMENT OVER MOVING NORTHEAST OUT OF OK INTO SE KS. WONDERING IF THE HIGHER CONFIDENCE SCENARIO (SUPPORTED BY THE RUC)...IS SHOWERS/THUNDERSTORMS RAMPING UP IN COVERAGE/INTENSITY LATER THIS EVENING OVER SOUTH-CENTRAL/CENTRAL KS IN RESPONSE TO INCREASING ISENTROPIC ASCENT AND MOISTURE TRANSPORT AHEAD OF APPROACHING DEEP MID/UPPER TROUGH...WITH A BROAD SHIELD OF MODERATE TO HEAVY SHOWERS/THUNDERSTORMS PUSHING EAST ACROSS EASTERN HALF OF KS OVERNIGHT ALONG THE ADVANCING 850-700MB FRONT. GIVEN THE PRESENCE OF AMPLE ELEVATED INSTABILITY AND EFFECTIVE DEEP LAYER SHEAR...LARGE HAIL IS POSSIBLE. POCKETS OF HEAVY RAIN AND MINOR FLOODING ARE POSSIBLE...ALONG WITH MODEST RISES IN AREA RIVERS...SO WILL KEEP THE FLOOD WATCH GOING OVER SOUTHEAST KS. ADDITIONALLY...ENOUGH LOW-LEVEL COLD AIR MAY FILTER SOUTHEAST TO RESULT IN A WINTRY MIX OVER CENTRAL KS AFTER MIDNIGHT...SO WILL KEEP A WINTER WX ADVISORY GOING THERE. ADK && UPDATE ISSUED AT 652 PM CDT WED APR 17 2013 UPDATED AVIATION SECTION BELOW. && .SHORT TERM...(THIS EVENING THROUGH SATURDAY) ISSUED AT 237 PM CDT WED APR 17 2013 CONVECTION PRE AND POST FRONTAL STRONG TO SEVERE CONVECTION WITH HEAVY RAINFALL EXPECTED THRU THIS EVENING ACROSS PORTIONS OF CENTRAL AND SOUTHEAST KANSAS. THE HIGHER IMPACT SEVERE IS STILL EXPECTED ALONG THE SURFACE FRONT ACROSS SOUTHEAST KANSAS WITH DAMAGING WINDS...LARGE HAIL AND A TORNADO POSSIBLE DURING THE EARLY EVENING. HOWEVER ELEVATED INSTABILITY OVER THE COLD AIR WILL STILL SUPPORT SOME HAILERS FURTHER WEST ACROSS PORTIONS OF CENTRAL KANSAS. CONVECTION WILL TEND TO REDEVELOP AND REPEAT/TRAIN OVER SOME AREAS WHICH PORTENDS TO HEAVY RAINFALL AND FLOOD POTENTIAL. THE LONGER DURATION APPEARS TO BE OVER SOUTHEAST KANSAS INTO THE OVERNIGHT HOURS...SO WILL ISSUE A FLOOD WATCH FOR THESE AREAS. WINTRY PRECIP NEXT CHALLENGE IS WITH THE SURGE OF COLD AIR AND POST FRONTAL PRECIPITATION LATER TONIGHT INTO THURSDAY MORNING. WHILE NOT QUITE AS IMPRESSIVE AS LAST WEEK...IT DOES LOOK LIKE WE WILL GET A TRANSIENT AREA OF A LIGHT WINTRY MIX ACROSS CENTRAL KANSAS WITH THE NAM PREFERRED IN THIS REGARD. DEPENDING ON CHANGEOVER AND MOISTURE DEPTH/LIFT...THIS COULD BE SOME LIGHT FREEZING RAIN AND/OR SNOW OR FREEZING DRIZZLE...THOUGH FOR NOW ANY ACCUMS ARE STILL EXPECTED TO BE LIGHT. THAT SAID...THIS IN COMBO WITH STRONG NORTH WINDS NEAR ADVISORY CRITERIA INTO EARLY THURSDAY MORNING...PLAN TO ISSUE A WINTER WEATHER ADVISORY FOR A PORTION OF CENTRAL KANSAS. SOME LIGHT MIXED PRECIP COULD BE OBSERVED AS FAR EAST AS THE FLINT HILLS INTO LATER THURSDAY MORNING...HOWEVER TEMPERATURES SHOULD RECOVER TO A BIT ABOVE FREEZING BY THEN SO OF LITTLE CONSEQUENCE EXPECTED. FREEZE/RECORD COLD THURSDAY NIGHT THE THIRD CONCERN IS WITH RECORD COLD AND WIDESPREAD FREEZE EXPECTED. THIS LOOKS TO BE A PURE COLD ADVECTION TYPE WITH MINS INTO THE MID TO UPPER 20S IN MOST LOCALES DESPITE A BIT OF NOCTURNAL/EARLY MORNING WIND. CONSIDERED A HEADLINE/WATCH FOR THIS...HOWEVER WITH THE OTHER MORE IMMINENT IMPACTS IN THE SHORTER TERM HAVE DECIDED TO HOLD OFF AND MAINTAIN MENTION IN THE HAZARDOUS WEATHER OUTLOOK. HOWEVER IF CONFIDENCE REMAINS HIGH...A FREEZE WARNING WILL LIKELY BE FORTHCOMING IN THE NEXT FORECAST CYCLE OR TWO. SOME MODERATION AND RETURN TO DRY WEATHER IS EXPECTED FOR FRIDAY AND SATURDAY AND MADE ONLY A SLIGHT UPTWEAK TO THE TEMPERATURES CLOSER TO SEASONAL CLIMO BY SATURDAY. DARMOFAL .LONG TERM...(SUNDAY THROUGH WEDNESDAY) ISSUED AT 237 PM CDT WED APR 17 2013 SINCE MAIN FOCUS HAS BEEN ON SHORT TERM DO NOT PLAN ON ANY SIGNIFICANT CHANGES TO THE OUTER PERIODS WITH THIS FORECAST. MEDIUM RANGE STILL SUPPORTS ANOTHER COOL DOWN EARLY NEXT WEEK WITH SOME PRECIP CHANCES AHEAD OF AND JUST BEHIND THE FRONTAL PASSAGE FROM SUNDAY INTO TUESDAY. DARMOFAL && .AVIATION...(FOR THE 00Z TAFS THROUGH 00Z THURSDAY EVENING) ISSUED AT 652 PM CDT WED APR 17 2013 A SHARP FRONTAL ZONE WILL BE THE FOCUS FOR NUMEROUS/WIDESPREAD SHOWERS AND THUNDERSTORMS ACROSS THE EASTERN 1/2 TO 2/3 OF KS TONIGHT. A RELATIVE LULL IN ACTIVITY IS ANTICIPATED THIS EVENING...WITH SHORT-RANGE GUIDANCE SUGGESTING WIDESPREAD SHOWERS/THUNDERSTORMS RAMPING UP BETWEEN 03-05Z. HEAVY RAINFALL...STRONG ERRATIC WINDS AND HAIL WILL BE POSSIBLE WITH STRONGEST ACTIVITY OVERNIGHT. AS COLDER AIR CONTINUES FILTERING SOUTHEAST...KRSL COULD POTENTIALLY SEE A MIX OF RAIN...FREEZING RAIN...SLEET AND SNOW AFTER 05Z. OTHERWISE...LIFR/IFR CIGS WILL GRADUALLY IMPROVE FROM THE NORTHWEST TONIGHT AND TOMORROW...AS COLDER AND DRIER AIR MOVES IN. ADK && .FIRE WEATHER... ISSUED AT 237 PM CDT WED APR 17 2013 GRASSLAND FIRE DANGER WILL REMAIN LOW DUE TO WIDESPREAD PRECIPITATION TONIGHT INTO EARLY THURSDAY. A DRYING PROCESS WILL BEGIN INTO THE START OF THE WEEKEND BEFORE ANOTHER CHANCE FOR RAIN SUNDAY INTO EARLY NEXT WEEK. KED && .PRELIMINARY POINT TEMPS/POPS... WICHITA-KICT 34 43 28 56 / 90 30 0 0 HUTCHINSON 32 41 27 56 / 90 30 0 0 NEWTON 33 41 27 54 / 90 40 0 0 ELDORADO 34 43 28 55 / 90 40 0 0 WINFIELD-KWLD 36 45 29 59 / 90 40 0 0 RUSSELL 29 40 24 56 / 90 50 0 0 GREAT BEND 29 40 25 56 / 90 30 0 0 SALINA 32 41 26 55 / 90 50 0 0 MCPHERSON 32 40 26 56 / 90 40 0 0 COFFEYVILLE 45 49 31 58 / 100 60 10 0 CHANUTE 44 46 30 57 / 100 60 10 0 IOLA 43 45 30 56 / 100 60 10 0 PARSONS-KPPF 45 48 30 56 / 100 60 10 0 && .ICT WATCHES/WARNINGS/ADVISORIES... WINTER WEATHER ADVISORY FROM 1 AM TO 7 AM CDT THURSDAY FOR KSZ032-033-047-048-050-067-082. FLOOD WATCH THROUGH THURSDAY MORNING FOR KSZ070>072-094>096- 098>100. && $$
AREA FORECAST DISCUSSION
NWS DODGE CITY KS
703 PM CDT WED APR 17 2013 ...UPDATED AVIATION SECTION FOR 00Z TAFS... .SYNOPSIS... ISSUED AT 343 PM CDT WED APR 17 2013 THE 12Z UPPER AIR ANALYSIS SHOWED A DEEP TROUGH EXTENDING FROM THE NORTHERN ROCKIES INTO THE GREAT BASIN. A 150+ KNOT UPPER LEVEL JET WAS IN THE BASE OF THE TROUGH OVER SOUTHERN ARIZONA AND NEW MEXICO. AT THE 850 MB LEVEL...LOW PRESSURE WAS CENTERED OVER NORTHERN NEW MEXICO. EAST OF THE LOW...A NEARLY STATIONARY FRONTAL BOUNDARY EXTENDED EAST ACROSS THE NORTHERN TEXAS PANHANDLE INTO SOUTH CENTRAL AND EASTERN KANSAS. AT THE SURFACE...THE FRONTAL BOUNDARY EXTENDED FROM EASTERN NEW MEXICO ACROSS WEST TEXAS AND THEN NORTHEAST ACROSS CENTRAL OKLAHOMA. WARM AND MOIST AIR WAS STREAMING NORTH ACROSS TEXAS INTO THE CENTRAL PLAINS AND WAS CONTRIBUTING TO A VERY UNSTABLE AIRMASS ACROSS OKLAHOMA INTO SOUTH CENTRAL AND SOUTHEAST KANSAS. && .SHORT TERM...(THIS EVENING THROUGH THURSDAY) ISSUED AT 343 PM CDT WED APR 17 2013 THERE WILL BE A CONTINUED THREAT FOR SEVERE WEATHER OVER SOUTH CENTRAL KANSAS THIS EVENING. THE NAM IS INDICATING THAT THE 850 MB FRONTAL BOUNDARY WILL BE IN THE AREA FROM COLDWATER AND MEDICINE LODGE TO ST JOHN THIS EVENING BEFORE SHIFTING SOUTH OF THE AREA BY MIDNIGHT. RAP MODEL SOUNDINGS SHOW AROUND 1500 J/KG OF ELEVATED CAPE IN THAT AREA. AS THE SOUTHWESTERN U.S. UPPER JET PROPAGATES EASTWARD INTO THE SOUTHERN PLAINS THIS EVENING...INCREASING UPWARD VERTICAL MOTION COULD AID IN THE DEVELOPMENT OF ADDITIONAL THUNDERSTORMS. THERE WILL BE A THREAT FOR HAIL UP TO QUARTER SIZE IN THAT AREA. THE UPPER TROUGH MOVES EAST OUT OVER THE HIGH PLAINS TONIGHT. MODEL SOUNDINGS ARE INDICATING SATURATED CONDITIONS GENERALLY BELOW 700 MB THROUGH THE NIGHT WITH THE LEVELS ABOVE 700 MB SATURATING FOR A 3-6 HOUR TIME FRAME DURING THE NIGHT. LOCATIONS FARTHER WEST ACROSS WESTERN KANSAS WILL SEE AREAS OF DRIZZLE CONTINUING ALONG WITH A CHANCE FOR RAIN SHOWERS. THERE WILL BE A TRANSITION FROM RAIN TO SNOW WITH A PERIOD OF SLEET/FREEZING RAIN POSSIBLE IN BETWEEN. THE ATMOSPHERE SHOULD COOL OFF ENOUGH FOR SNOW TO DEVELOP OVER WEST CENTRAL KANSAS DURING THE EVENING HOURS WITH THIS SPREADING INTO CENTRAL KANSAS AFTER MIDNIGHT. GIVEN THE SHORT WINDOW OF OPPORTUNITY FOR THE SEEDER/FEEDER MECHANISM TO OCCUR...DO NOT EXPECT SNOW AMOUNTS TO BE SIGNIFICANT WITH ONLY SOME LIGHT ACCUMULATIONS POSSIBLE ON GRASSY AREAS. AM NOT ANTICIPATING ANY SIGNIFICANT ICE ACCUMULATIONS TO OCCUR ALTHOUGH SOME ELEVATED SURFACES COULD GET SOME LIGHT COATINGS. AS COLD AIR ADVECTION INCREASES...STRONG NORTHERLY WINDS DEVELOP OVER THE WESTERN HIGH PLAINS AND SPREAD EASTWARD TONIGHT. LOW LEVEL WINDS THROUGH THE 850 MB LEVEL INCREASE TO 40-50 KNOTS OVERNIGHT WHICH SHOULD SUPPORT WIND ADVISORY CRITERIA WINDS LATER TONIGHT INTO THURSDAY MORNING. HAVE ISSUED A WIND ADVISORY FOR MIDNIGHT TONIGHT UNTIL NOON THURSDAY FOR ALL OF SOUTHWEST AND CENTRAL KANSAS. PRECIPITATION SHOULD BE WINDING DOWN FAIRLY QUICKLY LATE TONIGHT AND THURSDAY MORNING AS THE UPPER SYSTEM MOVES EAST OF THE REGION. CLOUDS SHOULD BE BREAKING UP FROM WEST TO EAST DURING THE DAY. WITH SOME SUN...AFTERNOON HIGH TEMPERATURES MAY BE ABLE TO CLIMB INTO THE LOWER 40S. .LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY) ISSUED AT 338 PM CDT WED APR 17 2013 FRIDAY: UPPER LEVEL WNW FLOW WILL CONTINUE ON FRIDAY. AT THE SURFACE, HIGH PRESSURE WILL RIDGE ACROSS THE PLAINS. NORTHWESTERLY WINDS WILL EVENTUALLY BECOME SOUTHERLY AFTER SUNSET. HIGHS WILL BE IN THE 50S AND LOWS WILL BE IN THE 20S. NO PRECIPITATION IS EXPECTED AS DRY FLOW ALOFT AND LACK OF BL MOISTURE CONTINUES. WEEKEND: AN UPPER LEVEL TROUGH WILL DIG ACROSS THE CENTRAL AND SOUTHERN ROCKIES THROUGH THE WEEKEND. THIS WILL PROMOTE A WARM AIR ADVECTION PATTERN DOWNSTREAM ACROSS OUR REGION. A WARM 850 HPA PLUME WILL ADVECT OFF THE ROCKIES AND OUT ACROSS SOUTHWEST KANSAS SATURDAY. THIS WILL FAVOR DEEP MIXING AND HIGHS IN THE UPPER 60S TO LOWER 70S. OVERNIGHT LOWS WILL MODERATE AS WELL WITH 30S ON SATURDAY AND 40S ON SUNDAY. TEMPERATURES AROUND 70 DEG F CAN BE EXPECTED SUNDAY AS THE AFOREMENTIONED WARM PLUME CONTINUES ACROSS THE REGION. THERE COULD BE A FEW SHOWERS ACROSS SC/S KANSAS IN ASSOCIATION WITH WARM ADVECTION BUT CONFIDENCE IS LOW AND MODELS ARE FAIRLY LIGHT ON QPF. NEXT WEEK AND BEYOND: A MAJOR CHANGE IN WEATHER IS POSSIBLE MONDAY OR TUESDAY. ANOTHER TROF DIGGING OUT OF THE NORTHERN ROCKIES WILL USHER IN THE PASSAGE OF A SIGNIFICANT COLD FRONT. THE ECMWF IS FAIRLY COLD WITH 850 HPA TEMPERATURES DECREASING DOWN TO -6 DEG C. BOTH THE GFS AND ECMWF INDICATE SOME LIGHT SNOWFALL ACROSS THE REGION ASSOCIATED WITH THIS FRONT. CONFIDENCE IS LOW FOR PRECIPITATION TYPE BUT THERE IS HIGHER CONFIDENCE IN LOWER TEMPERATURES WITH 40S AND 50S FOR HIGHS BY TUESDAY/WEDNESDAY. && .AVIATION...(FOR THE 00Z TAFS THROUGH 00Z THURSDAY EVENING) ISSUED AT 659 PM CDT WED APR 17 2013 POOR AVIATION CONDITIONS WILL CONTINUE THROUGH THE NIGHT AS A ROUND OF PRECIPITATION DEVELOPS THIS EVENING AND LINGERS THROUGH THE OVERNIGHT HOURS. THE PRECIPITATION TYPE WILL BE RAIN AT GCK, DDC, AND HYS THROUGH THE LATE EVENING...BUT A TRANSITION TO SLEET AND/OR SNOW IS EXPECTED LATE THIS EVENING AND ESPECIALLY AFTER MIDNIGHT. ONLY LIGHT PRECIPITATION IS EXPECTED, HOWEVER, AFTER MIDNIGHT SO NO ACCUMULATION OF SIGNIFICANCE IS EXPECTED. STRONG NORTH WINDS OF 25 OR MORE KNOTS WILL DEVELOP LATE AS THE MAIN UPPER LEVEL STORM SYSTEM APPROACHES. IFR CEILINGS WILL PREVAIL AT LEAST THROUGH THE MID MORNING HOURS THURSDAY...BUT GRADUALLY SCATTERING OUT TO VFR CONDITIONS THEREAFTER AS THE STORM EXITS THE WESTERN PLAINS. && .PRELIMINARY POINT TEMPS/POPS... DDC 27 38 24 59 / 70 10 0 0 GCK 27 37 22 60 / 60 10 0 0 EHA 26 39 23 60 / 40 10 0 0 LBL 28 41 23 60 / 50 10 0 0 HYS 28 36 23 58 / 80 30 0 0 P28 31 44 28 60 / 70 10 0 0 && .DDC WATCHES/WARNINGS/ADVISORIES... WIND ADVISORY FROM MIDNIGHT CDT /11 PM MDT/ TONIGHT TO NOON CDT /11 AM MDT/ THURSDAY FOR KSZ030-031-043>046-061>066-074>081- 084>090. && $$ SYNOPSIS...GERARD SHORT TERM...GERARD LONG TERM...SUGDEN AVIATION...UMSCHEID
AREA FORECAST DISCUSSION
NWS GOODLAND KS
512 PM MDT WED APR 17 2013 .SHORT TERM...(THIS AFTERNOON THROUGH THURSDAY) ISSUED AT 132 PM MDT WED APR 17 2013 EARLY AFTERNOON WV IMAGERY AND RAP H5 ANALYSIS SHOWS POSITIVELY TITLED LONGWAVE TROUGH EXTENDING SOUTH ALONG CENTRAL ROCKIES WITH DRY SLOT/AREA OF SUBSIDENCE IN PLACE AHEAD OF THIS OVER WESTERN KANSAS AND CENTRAL NEBRASKA. LOW AT THE SURFACE A STALLED FRONT EXTENDS FROM THE TEXAS PANHANDLE ACROSS CENTRAL OKLAHOMA TO SOUTHEAST KANSAS. NORTHWEST FLOW IS IN PLACE ACROSS OUR CWA WITH VERY MOIST BL CONDITIONS PERSISTING...WHICH HAS RESULTED IN AREAS OF FOG AND DRIZZLE PERSISTING THROUGH THE AFTERNOON HOURS. WITH TEMPERATURES NEAR OR BELOW FREEZING...WE COULD CONTINUE TO SEE LIGHT ICE ACCUMULATIONS ON ELEVATED SURFACES BEFORE SNOW DEVELOPS LATER. THE PRIMARY FORECAST FOCUS IS ON DEVELOPING WINTER STORM FOR LATE THIS AFTERNOON THROUGH EARLY THURSDAY MORNING. UPPER LEVEL TROUGH IS PROGGED TO SHIFT EAST THIS EVENING...WITH LARGE SCALE ASCENT AND MID LEVEL MOISTURE OVERSPREADING THE CWA. BROAD AXIS OF MID LEVEL FRONTOGENESIS IS EXPECTED TO SET UP ACROSS THE NORTHWEST HALF OF OUR CWA THIS EVENING. LIGHT SNOW AND BANDS OF MODERATE SNOW TRAINING FROM THE SOUTH TO THE NORTH. WITH SURFACE TEMPS ALREADY BELOW FREEZING THIS AFTERNOON IN THE NORTHWEST AND A SECOND COLD SURGE EXPECTED LATE THIS AFTERNOON/EARLY THIS EVENING...I THINK WE SHOULD SEE A FAST RAIN/SNOW CHANGEOVER WITH ALL SNOW IN OUR CWA THIS EVENING AND TONIGHT. THERE IS QUITE A BIT OF SPREAD REGARDING QPF VALUES...WITH GFS THE HIGH OUTLIER. WITH SREF (TRADITIONALLY HIGH) AND OTHER GUIDANCE MORE IN LINE WITH PREVIOUS FORECAST QPF/SNOW TOTALS I DISCOUNTED THE GFS SOLUTION AND ONLY MADE MINOR CHANGES TO AMOUNTS. WE ARE CURRENTLY FORECAST 3-5 INCHES FOR MOST OF THE AREA...WITH HIGHS AMOUNTS MORE LIKELY NORTH OF INTERSTATE 70. OTHER CONCERN (AND POSSIBLY THE HIGHER IMPACT) IS STRONG WINDS PROGGED TO DEVELOP THIS EVENING. ALL GUIDANCE IS SUPPORTIVE OF GUSTY WINDS...HOWEVER GFS/MAV CONTINUES TO BE THE HIGH OUTLIER WITH GUSTS IN EXCESS OF 60 MPH. NAM/SREF/ECMWF ALL ARE LOWER...AND WITH BEST PRESSURE RISES ADVERTISED TO BE FURTHER SOUTH...THESE SOLUTIONS MAY BE MORE REASONABLE. I USED A BLEND THAT FAVORED THE NAM MIXED LAYER WINDS AND NUDGED A LITTLE TOWARDS GFS/MAV WHICH RESULTS IN GUSTS THIS EVENING TO 50 MPH. EVEN WITH THE LOWER END OF GUIDANCE WE SHOULD SEE BLOWING SNOW WITH REDUCED VISIBILITIES. THE SPREAD IN GUIDANCE AND POSSIBLE LIMITED DURATION OF THE STRONGEST WINDS IN OUR AREA RAISES QUESTIONS TO HOW LOW THESE VISIBILITIES WILL BE AND HOW LONG. I FELT THE WINTER WEATHER ADVISORY WAS APPROPRIATE WITH BRIEF BLIZZARD CONDITIONS POSSIBLE. IF WINDS END UP BEING MORE IN LINE WITH GFS SOLUTION WE MAY NEED TO CONVERT WESTERN LOCATIONS TO A BLIZZARD WARNING...CONFIDENCE JUST ISNT THERE RIGHT NOW. THE WORST CONDITIONS SHOULD BE 03Z THROUGH ABOUT 09Z TONIGHT...WITH SNOW ENDING QUICKLY FROM THE WEST TO THE EAST EARLY THU MORNING. WE COULD SEE LINGERING SNOW INTO THU IN OUR NORTHEAST...HOWEVER WITH BEST FORCING/MOISTURE OUTSIDE OUR AREA I AM NOT ANTICIPATING VERY MUCH ADDITIONAL ACCUMULATION. WE SHOULD SEE ANOTHER BLUSTERY DAY THURSDAY WITH HIGHS IN THE 30S AND GUSTY WINDS THROUGH THE DAY. GFS/MAV IS AGAIN MUCH HIGHER ON WINDS THU AND MIGHT SUPPORT ADVISORY CRITERIA. I WILL HAVE TO SEE WHAT KIND OF BIAS THE GFS HAD TONIGHT TO HAVE ANY ANY CONFIDENCE IN THE HIGHER WINDS THURSDAY. .LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY) ISSUED AT 316 PM MDT WED APR 17 2013 FORECAST PROBLEMS WILL BE HOW MUCH IT WARMS UP THROUGH THE WEEKEND BEFORE THE NEXT COLD FRONT MOVES THROUGH AND THE PRECIPITATION CHANCES THIS WEEKEND AND CONTINUING INTO THE BEGINNING OF NEXT WEEK. SATELLITE SHOWING THE LARGE SCALE FLOW PATTERN BEING AMPLIFIED AND BLOCKY FROM THE PACIFIC INTO THE EASTERN NORTH AMERICA. THURSDAY NIGHT...SYSTEM THAT WILL HAVE BROUGHT THE AREA SNOW AND WIND WILL CONTINUE TO MOVE AWAY. MODERATE GRADIENT CONTINUES THROUGH THE NIGHT AND LOOKS LIKE THE WINDS WILL STAY UP ENOUGH TO KEEP THE TEMPERATURES FROM BOTTOMING OUT. FRIDAY/FRIDAY NIGHT...RIGHT REAR QUADRANT OF UPPER JET GOES ACROSS THE NORTHERN PORTION OF THE AREA DURING THE DAY. AT THIS TIME WITH A LARGE DRY LAYER IN THE LOW AND MID LEVELS...THIS ONLY LOOKS LIKE IT WILL SPREAD CLOUDS ACROSS THE AREA. DURING THE NIGHT...THE LEFT FRONT QUADRANT IS NEAR OR JUST SOUTHWEST OF THE SOUTHWEST PORTION OF OUR AREA. AS IT LOOKS THE MAIN MID LEVEL LIFT LOOKS TO STAY TO NORTH AND SOUTH OF THE AREA. ALSO PROBLEM AGAIN LOOKS TO BE A LACK OF MOISTURE IN THE LOW LEVELS. SO WILL KEEP THIS PERIOD DRY AS WELL. CLOUDS WILL DECREASE THROUGH THE NIGHT WITH THE MODELS SHOWING A HIGHLY VARIABLE WIND FIELD AND DISAGREE WITH EACH OTHER. WILL TEND TOWARD THE COOLER SIDE. SATURDAY...MAIN JET REMAINS SOUTH AND WEST OF THE AREA. HIGHER LEVEL CLOUD COVER INCREASES THROUGH THE DAY AS A COUPLE DIFFERENT SHORTWAVE TROUGHS MOVE THROUGH. THIS MAY HINDER THE TEMPERATURES. HOWEVER... MODELS HAVE BEEN MISSING THE BOAT ON TEMPERATURES HERE RECENTLY. HAVE A LIGHT AND VARIABLE WIND FIELD WHICH ALSO DOES NOT BODE WELL FOR GOING TOO WARM. MODELS HANDLE THIS DIFFERENTLY DUE TO THE DIFFERENT HANDLING OF THE INCOMING SYSTEM. 700 TO 500 MB PATTERN WOULD DEFINITELY SUPPORT AN EARLIER SURFACE TROUGH/FRONTAL PASSAGE. MORE SUPPORT FOR GOING WARMER SO DID NUDGE UP TEMPERATURES A LITTLE BUT NOT A LOT OF CONFIDENCE IN THIS DUE TO RECENT TEMPERATURE PERFORMANCE. NOT A LOT OF SURFACE CONVERGENCE WITH THIS WIND FIELD. PLUS ALL THE MOISTURE LOOKS TO BE ABOVE 700 MB. SO WILL KEEP THIS PERIOD DRY. SATURDAY NIGHT THROUGH WEDNESDAY...IN GENERAL THE MODELS ARE CAPTURING THE OVERALL PATTERN. THE MODELS DROP A SYSTEM INTO THE NORTH CENTRAL PORTION OF THE COUNTRY SUNDAY INTO MONDAY AND THEN BRING THE UPPER TROUGH THROUGH AROUND TUESDAY AND THEN EAST OF THE AREA. HOWEVER...THEY ARE DIFFERING ON THE TIMING OF THE NUMEROUS SHORTWAVE TROUGHS THAT MOVE THROUGH IN THE WESTERLY FLOW ALOFT PRIOR TO THE UPPER TROUGH MOVING THROUGH. THEY ALSO DIFFER IN HOW FAR SOUTH AND HOW FAST THEY TAKE THE UPPER TROUGH THROUGH. SO IN GENERAL THEY AGREE ON MAKING IT WET BUT NOT THE TIMING. THE BIGGEST PROBLEM ON TIMING CENTERS AROUND TUESDAY. THE ECMWF TAKES THE UPPER TROUGH THROUGH SOONER THAN THE GFS AND CANADIAN. SO DID NOT HAVE ANY PROBLEM WITH WHAT THE CRH INIT GAVE ME WHICH IS RAMPING UP POPS SUNDAY NIGHT WITH THE HIGHEST POPS MONDAY INTO MONDAY NIGHT. FOR TUESDAY THE INIT GAVE ME POPS IN THE MIDDLE OF THE TWO CAMPS AND COULD LIVE WITH THAT. AFTER TUESDAY IT LOOKS DRY. STRONG COLD FRONT COMES THROUGH LATE SUNDAY NIGHT INTO EARLY MONDAY MORNING. PER THIS RATHER FAST FRONTAL PASSAGE AND COLLABORATION CHOSE TO LOWER MONDAY AND TUESDAY MAXES FROM WHAT THE CRH INIT GAVE ME. OTHERWISE MADE NO OTHER CHANGES THANKS TO ALL FOR THE COLLABORATION && .AVIATION...(FOR THE 00Z TAFS THROUGH 00Z THURSDAY EVENING) ISSUED AT 511 PM MDT WED APR 17 2013 DYNAMICS FROM THE UPPER TROUGH WILL MOVE ACROSS THE TERMINALS TONIGHT BRINGING LIGHT SNOW FOR SEVERAL HOURS UNTIL AROUND 14Z THURSDAY. STRONG NORTH WIND WILL CAUSE SOME BLOWING SNOW AND REDUCED VISIBILITIES WITH CONDITIONS DROPPING TO LIFR. CONDITIONS SHOULD IMPROVE TO MVFR BY AFTERNOON AS THE SYSTEM MOVES AWAY. && .CLIMATE... ISSUED AT 330 AM MDT WED APR 17 2013 RECORD LOW HIGH TEMPERATURES IN JEOPARDY THURSDAY: GOODLAND.....38 DEGREES HILL CITY....47 DEGREES MCCOOK.......35 DEGREES BURLINGTON...35 DEGREES YUMA.........36 DEGREES COLBY........39 DEGREES TRIBUNE......40 DEGREES && .GLD WATCHES/WARNINGS/ADVISORIES... KS...WINTER WEATHER ADVISORY UNTIL 6 AM MDT /7 AM CDT/ THURSDAY FOR KSZ001>004-013>016-027>029-041-042. CO...WINTER WEATHER ADVISORY UNTIL 6 AM MDT THURSDAY FOR COZ090>092. NE...WINTER WEATHER ADVISORY UNTIL 6 AM MDT /7 AM CDT/ THURSDAY FOR NEZ079>081. && $$ SHORT TERM...DR LONG TERM...BULLER AVIATION...FS CLIMATE...JTL
AREA FORECAST DISCUSSION
NWS TOPEKA KS
1206 AM CDT TUE APR 16 2013 .UPDATE... ISSUED AT 1059 PM CDT MON APR 15 2013 LATEST MODEL GUIDANCE...PARTICULARLY THE RAP AND 00Z NAM SUGGEST THAT THE BAND OF ISENTROPIC ASCENT CURRENTLY FEEDING THUNDERSTORMS FROM SOUTHEAST KANSAS INTO MISSOURI WILL REMAIN FOCUSED OVER THE AREA ALREADY SEEING TSTORM ACTIVITY. WHILE A FEW CELLS MAY DEVELOP TO THE NORTH OF THE MAIN BAND OF ACTIVITY...THERE SEEMS TO BE LIMITED INSTABILITY TO THE NORTH AND PERHAPS EVEN AN ELEVATED CAP INHIBITING MORE ROBUST DEVELOPMENT. SO WITH THIS UPDATE HAVE KEPT MOST THUNDERSTORM CHANCES SOUTH OF I-35 THROUGH AROUND 09Z...AND USING THIS REASONING HAVE ALSO KEPT THE SEVERE THUNDERSTORM WATCH SOUTH OF THE LOCAL FORECAST AREA FOR NOW. HOWEVER...BY 08Z TO 10Z...EXPECT AN AREA OF LOW LEVEL MOISTURE CURRENTLY EVIDENT OVER CENTRAL AND NORTH CENTRAL OKLAHOMA TO STREAM NORTH ON THE NOSE OF AN INTENSIFYING LOW LEVEL JET. THIS WARM MOIST AIRMASS WILL UNDERCUT SLIGHTLY STEEPER MID LEVEL LAPSE RATES THAT ARE ADVECTING IN FROM SOUTHWEST KANSAS...EVIDENT ON THE 00Z DDC UPPER AIR SOUNDING. AS THIS WARM MOIST ADVECTION BECOMES DEEP ENOUGH AND ISENTROPIC ASCENT IS ENHANCED WITHIN IT...AGAIN PROBABLY IN THE 08Z TO 10Z TIME PERIOD...EXPECT SCATTERED THUNDERSTORMS TO DEVELOP FROM SOUTH CENTRAL KANSAS NORTH INTO THE EMPORIA AREA...AND EVENTUALLY FARTHER NORTH TOWARD THE I-70 CORRIDOR. MUCAPE INITIALLY SHOULD BE IN THE 400 TO 800 J/KG RANGE WITH SOME INDICATIONS OF INCREASING CLOSER TO 1000 TO 1500 J/KG AFTER SUNRISE. EFFECTIVE SHEAR ALOFT WILL BE QUITE STRONG AND WILL SUPPORT STORM ORGANIZATION. IF THE STRONGER INSTABILITY COMES TO FRUITION...COULD POTENTIALLY SEE A FEW STORMS PRODUCE SEVERE HAIL MAINLY ALONG AND SOUTH OF I-70 AND PROBABLY AROUND SUNRISE OR THEREAFTER. COULD BE A MARGINAL EVENT AS CONVECTIVE INTERACTIONS MAY MITIGATE STORM STRENGTH. WILL HAVE TO MONITOR THE SITUATION CLOSELY AS THE EVENING PROGRESSES REGARDING EVENTUAL SEVERE HAIL POTENTIAL. TO THE NORTH...AN AREA OF VERY LIGHT RAIN AND SNOW WAS EVIDENT ON RADAR IN SOUTHERN NEBRASKA. THIS ACTIVITY SHOULD STAY NORTH OF THE LOCAL FORECAST AREA BUT I SUPPOSE A SPRINKLE OR SNOWFLAKE WOULD NOT BE COMPLETELY OUT OF THE QUESTION IN FAR NORTH CENTRAL KANSAS. BARJENBRUCH && .SHORT TERM...(THIS EVENING THROUGH TUESDAY) ISSUED AT 359 PM CDT MON APR 15 2013 FRONTAL BOUNDARY REMAINS SOUTH OF KANSAS ACROSS OKLAHOMA NORTHEAST INTO MISSOURI AT 19Z. SOME CLEARING OF MID LEVEL DECK OCCURRING ACROSS THE NORTH CENTRAL KANSAS COUNTIES WHILE SOLID OVERCAST CONTINUES ACROSS EAST CENTRAL KANSAS. THE COMBINATION OF NORTHERLY WINDS AND CLOUDS HAVE KEPT TEMPERATURES COOLER THAN EARLIER FORECAST AND MADE ADJUSTMENTS DOWNWARD. TONIGHT...ISENTROPIC LIFT OVER THE BOUNDARY WILL DEVELOP ELEVATED SHOWERS AND SOME THUNDERSTORMS ACROSS THE AREA LATER TONIGHT. PROFILERS ALREADY SHOWING SOUTHERLY 925MB-850MB WINDS IN EASTERN OKLAHOMA. ISENTROPIC LIFT ON THE 300K SURFACE AND THE 305K SURFACE INCREASES AFTER 06Z TONIGHT. BETTER ELEVATED INSTABILITY WILL BE SOUTHEAST OF THE TURNPIKE. ELEVATED CAPE OF ONLY 100-200 J/KG FORECAST OVERNIGHT. LOWS TONIGHT WILL COOL INTO THE MID 30S NORTH CENTRAL TO THE MID 40S EAST CENTRAL. SHOWERS AND THUNDERSTORMS WILL CONTINUE THROUGH THE MORNING HOURS THEN DECREASE SOME IN THE AFTERNOON. EML STRENGTHENS TUESDAY AFTERNOON ACROSS THE AREA. HIGHS TUESDAY WILL ONLY BE IN THE UPPER 40S TO LOWER 50S. .LONG TERM...(TUESDAY NIGHT THROUGH MONDAY) ISSUED AT 359 PM CDT MON APR 15 2013 WARM AIR AND MOISTURE ADVECTION WILL DRAMATICALLY INCREASE TUESDAY NIGHT AS A STRONG LLVL JET DEVELOPS. THIS WILL ESPECIALLY BE THE CASE IN THE OVERNIGHT HOURS. ELEVATED CAPE WILL INCREASE INTO THE 1200-1800 J/KG RANGE ACROSS MUCH OF THE SOUTH COUNTY WARNING. WITH DECREASING INHIBITION...EXPECT AT LEAST SCATTERED THUNDERSTORMS TO DEVELOP WHICH COULD PRODUCE LARGE HAIL THROUGH SUNRISE ACROSS AREAS GENERALLY ALONG AND SOUTH OF I 70 AS THE WARM FRONT REMAINS GENERALLY SOUTH OF THE COUNTY WARNING AREA. MODELS SHOW CONSIDERABLE DIFFERENCES IN THE TIMING OF THE STRONG UPPER LEVEL TROUGH COMING OUT OF THE ROCKIES BY WEDNESDAY NIGHT AND HOW FAR THE WARM FRONT AND SFC LOW DEVELOPS/MOVES. HAVE LEANED MORE TOWARDS A MORE SOUTHERLY TRACK OF THE SFC LOW AND ASSOCIATED WARM FRONT WITH AN INVERTED TROUGH EXTENDING NORTHEAST FROM THE LOW INTO THE CWA WEDNESDAY. AS THE FLOW ALOFT INCREASES AND MOISTURE CONTINUES TO SURGE NORTHWARD AS THE MAIN DYNAMICS OF THE SYSTEM ROTATE OUT INTO THE PLAINS EXPECT MULTIPLE ROUNDS OF CONVECTION ACROSS MOST OF THE CWA TUESDAY NIGHT THROUGH WEDNESDAY NIGHT...SOME OF WHICH COULD PRODUCE LARGE HAIL...ALTHOUGH STRONG WINDS WILL ALSO BE POSSIBLE AHEAD OF THE ADVANCING TROUGH WEDNESDAY AND WEDNESDAY EVENING. LOCALLY HEAVY RAINFALL AMOUNTS WILL ALSO BE POSSIBLE ESPECIALLY ACROSS THE SOUTHEAST HALF OF THE CWA. FAVORED THE EC MODEL IN THE OUTER PERIODS OF THIS SYSTEM AS IT EJECTS OUT INTO THE PLAINS THURSDAY WITH A RAIN SNOW MIX POSSIBLE IN THE FAR NORTH CENTRAL COUNTIES LATE WEDNESDAY NIGHT THEN ACROSS THE NORTHWEST HALF THURSDAY AND THE FAR NORTH THURSDAY EVENING AS COLDER AIR SURGES IN WITHIN THE WRAPAROUND MOISTURE FIELD ON THE BACKSIDE OF THE DEPARTING SYSTEM. DO NOT HAVE HIGH ENOUGH CONFIDENCE TO GO ALL SNOW AT THIS POINT IN ANY ONE LOCATION. THERE WILL BE A LARGE A DIFFICULT TO FORECAST TEMPERATURE SPREAD ACROSS THE CWA WITH THE FRONT ON WEDNESDAY. FOR NOW WILL GO WITH THE UPPER 40S NORTH CENTRAL TO NEAR 70 IN THE FAR SOUTHEAST CORNER. TEMPERATURES WILL THEN FALL INTO THURSDAY WITH HIGHS FROM THE UPPER 30S NORTH CENTRAL TO THE 40S ELSEWHERE. THE MODELS ARE STILL IN AGREEMENT THAT AFTER THE DEEP TROUGH PASSES THROUGH THE AREA THURSDAY...IT SHOULD BE DRY UNTIL THE PASSAGE OF ANOTHER SHORTWAVE TROUGH OCCURS SUNDAY INTO MONDAY. THIS WILL BE THE NEXT CHANCE FOR SHOWERS. HIGHS FOLLOWING THE THURSDAY SYSTEM WILL REMAIN BELOW NORMAL WITH READINGS IN THE UPPER 40S AND LOW 50S FRIDAY THEN THE 60S FOR SATURDAY INTO MONDAY. FROST AND OR FREEZING TEMPERATURES REMAIN A CONCERN PRIMARILY FOR FRIDAY AND SATURDAY MORNINGS. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z TUESDAY NIGHT) ISSUED AT 1203 AM CDT TUE APR 16 2013 VFR CONDITIONS ARE EXPECTED THROUGH AROUND 22Z. A WINDOW OF THUNDERSTORM POTENTIAL EXISTS BETWEEN AROUND 10Z AND 18Z...WITH BEST CHANCE FOR TS AT FOE/TOP. TS WILL BE SCATTERED IN NATURE AND NOT PREDOMINANT...AND MAY STAY SOUTH OF TAF SITES SO DID NOT INCLUDE TSRA IN THE TAF AT THIS TIME. IF STRONG STORMS MOVE OVERHEAD...HAIL WILL BE POSSIBLE. MVFR CIGS SHOULD BUILD IN BY LATE AFTERNOON/EVENING. && .TOP WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...BARJENBRUCH SHORT TERM...53 LONG TERM...63 AVIATION...BARJENBRUCH
AREA FORECAST DISCUSSION
NWS TOPEKA KS
1116 PM CDT MON APR 15 2013 ...UPDATED FORECAST FOR THUNDERSTORM EXPECTATIONS THROUGH MORNING... .UPDATE... ISSUED AT 1059 PM CDT MON APR 15 2013 LATEST MODEL GUIDANCE...PARTICULARLY THE RAP AND 00Z NAM SUGGEST THAT THE BAND OF ISENTROPIC ASCENT CURRENTLY FEEDING THUNDERSTORMS FROM SOUTHEAST KANSAS INTO MISSOURI WILL REMAIN FOCUSED OVER THE AREA ALREADY SEEING TSTORM ACTIVITY. WHILE A FEW CELLS MAY DEVELOP TO THE NORTH OF THE MAIN BAND OF ACTIVITY...THERE SEEMS TO BE LIMITED INSTABILITY TO THE NORTH AND PERHAPS EVEN AN ELEVATED CAP INHIBITING MORE ROBUST DEVELOPMENT. SO WITH THIS UPDATE HAVE KEPT MOST THUNDERSTORM CHANCES SOUTH OF I-35 THROUGH AROUND 09Z...AND USING THIS REASONING HAVE ALSO KEPT THE SEVERE THUNDERSTORM WATCH SOUTH OF THE LOCAL FORECAST AREA FOR NOW. HOWEVER...BY 08Z TO 10Z...EXPECT AN AREA OF LOW LEVEL MOISTURE CURRENTLY EVIDENT OVER CENTRAL AND NORTH CENTRAL OKLAHOMA TO STREAM NORTH ON THE NOSE OF AN INTENSIFYING LOW LEVEL JET. THIS WARM MOIST AIRMASS WILL UNDERCUT SLIGHTLY STEEPER MID LEVEL LAPSE RATES THAT ARE ADVECTING IN FROM SOUTHWEST KANSAS...EVIDENT ON THE 00Z DDC UPPER AIR SOUNDING. AS THIS WARM MOIST ADVECTION BECOMES DEEP ENOUGH AND ISENTROPIC ASCENT IS ENHANCED WITHIN IT...AGAIN PROBABLY IN THE 08Z TO 10Z TIME PERIOD...EXPECT SCATTERED THUNDERSTORMS TO DEVELOP FROM SOUTH CENTRAL KANSAS NORTH INTO THE EMPORIA AREA...AND EVENTUALLY FARTHER NORTH TOWARD THE I-70 CORRIDOR. MUCAPE INITIALLY SHOULD BE IN THE 400 TO 800 J/KG RANGE WITH SOME INDICATIONS OF INCREASING CLOSER TO 1000 TO 1500 J/KG AFTER SUNRISE. EFFECTIVE SHEAR ALOFT WILL BE QUITE STRONG AND WILL SUPPORT STORM ORGANIZATION. IF THE STRONGER INSTABILITY COMES TO FRUITION...COULD POTENTIALLY SEE A FEW STORMS PRODUCE SEVERE HAIL MAINLY ALONG AND SOUTH OF I-70 AND PROBABLY AROUND SUNRISE OR THEREAFTER. COULD BE A MARGINAL EVENT AS CONVECTIVE INTERACTIONS MAY MITIGATE STORM STRENGTH. WILL HAVE TO MONITOR THE SITUATION CLOSELY AS THE EVENING PROGRESSES REGARDING EVENTUAL SEVERE HAIL POTENTIAL. TO THE NORTH...AN AREA OF VERY LIGHT RAIN AND SNOW WAS EVIDENT ON RADAR IN SOUTHERN NEBRASKA. THIS ACTIVITY SHOULD STAY NORTH OF THE LOCAL FORECAST AREA BUT I SUPPOSE A SPRINKLE OR SNOWFLAKE WOULD NOT BE COMPLETELY OUT OF THE QUESTION IN FAR NORTH CENTRAL KANSAS. BARJENBRUCH && .SHORT TERM...(THIS EVENING THROUGH TUESDAY) ISSUED AT 359 PM CDT MON APR 15 2013 FRONTAL BOUNDARY REMAINS SOUTH OF KANSAS ACROSS OKLAHOMA NORTHEAST INTO MISSOURI AT 19Z. SOME CLEARING OF MID LEVEL DECK OCCURRING ACROSS THE NORTH CENTRAL KANSAS COUNTIES WHILE SOLID OVERCAST CONTINUES ACROSS EAST CENTRAL KANSAS. THE COMBINATION OF NORTHERLY WINDS AND CLOUDS HAVE KEPT TEMPERATURES COOLER THAN EARLIER FORECAST AND MADE ADJUSTMENTS DOWNWARD. TONIGHT...ISENTROPIC LIFT OVER THE BOUNDARY WILL DEVELOP ELEVATED SHOWERS AND SOME THUNDERSTORMS ACROSS THE AREA LATER TONIGHT. PROFILERS ALREADY SHOWING SOUTHERLY 925MB-850MB WINDS IN EASTERN OKLAHOMA. ISENTROPIC LIFT ON THE 300K SURFACE AND THE 305K SURFACE INCREASES AFTER 06Z TONIGHT. BETTER ELEVATED INSTABILITY WILL BE SOUTHEAST OF THE TURNPIKE. ELEVATED CAPE OF ONLY 100-200 J/KG FORECAST OVERNIGHT. LOWS TONIGHT WILL COOL INTO THE MID 30S NORTH CENTRAL TO THE MID 40S EAST CENTRAL. SHOWERS AND THUNDERSTORMS WILL CONTINUE THROUGH THE MORNING HOURS THEN DECREASE SOME IN THE AFTERNOON. EML STRENGTHENS TUESDAY AFTERNOON ACROSS THE AREA. HIGHS TUESDAY WILL ONLY BE IN THE UPPER 40S TO LOWER 50S. .LONG TERM...(TUESDAY NIGHT THROUGH MONDAY) ISSUED AT 359 PM CDT MON APR 15 2013 WARM AIR AND MOISTURE ADVECTION WILL DRAMATICALLY INCREASE TUESDAY NIGHT AS A STRONG LLVL JET DEVELOPS. THIS WILL ESPECIALLY BE THE CASE IN THE OVERNIGHT HOURS. ELEVATED CAPE WILL INCREASE INTO THE 1200-1800 J/KG RANGE ACROSS MUCH OF THE SOUTH COUNTY WARNING. WITH DECREASING INHIBITION...EXPECT AT LEAST SCATTERED THUNDERSTORMS TO DEVELOP WHICH COULD PRODUCE LARGE HAIL THROUGH SUNRISE ACROSS AREAS GENERALLY ALONG AND SOUTH OF I 70 AS THE WARM FRONT REMAINS GENERALLY SOUTH OF THE COUNTY WARNING AREA. MODELS SHOW CONSIDERABLE DIFFERENCES IN THE TIMING OF THE STRONG UPPER LEVEL TROUGH COMING OUT OF THE ROCKIES BY WEDNESDAY NIGHT AND HOW FAR THE WARM FRONT AND SFC LOW DEVELOPS/MOVES. HAVE LEANED MORE TOWARDS A MORE SOUTHERLY TRACK OF THE SFC LOW AND ASSOCIATED WARM FRONT WITH AN INVERTED TROUGH EXTENDING NORTHEAST FROM THE LOW INTO THE CWA WEDNESDAY. AS THE FLOW ALOFT INCREASES AND MOISTURE CONTINUES TO SURGE NORTHWARD AS THE MAIN DYNAMICS OF THE SYSTEM ROTATE OUT INTO THE PLAINS EXPECT MULTIPLE ROUNDS OF CONVECTION ACROSS MOST OF THE CWA TUESDAY NIGHT THROUGH WEDNESDAY NIGHT...SOME OF WHICH COULD PRODUCE LARGE HAIL...ALTHOUGH STRONG WINDS WILL ALSO BE POSSIBLE AHEAD OF THE ADVANCING TROUGH WEDNESDAY AND WEDNESDAY EVENING. LOCALLY HEAVY RAINFALL AMOUNTS WILL ALSO BE POSSIBLE ESPECIALLY ACROSS THE SOUTHEAST HALF OF THE CWA. FAVORED THE EC MODEL IN THE OUTER PERIODS OF THIS SYSTEM AS IT EJECTS OUT INTO THE PLAINS THURSDAY WITH A RAIN SNOW MIX POSSIBLE IN THE FAR NORTH CENTRAL COUNTIES LATE WEDNESDAY NIGHT THEN ACROSS THE NORTHWEST HALF THURSDAY AND THE FAR NORTH THURSDAY EVENING AS COLDER AIR SURGES IN WITHIN THE WRAPAROUND MOISTURE FIELD ON THE BACKSIDE OF THE DEPARTING SYSTEM. DO NOT HAVE HIGH ENOUGH CONFIDENCE TO GO ALL SNOW AT THIS POINT IN ANY ONE LOCATION. THERE WILL BE A LARGE A DIFFICULT TO FORECAST TEMPERATURE SPREAD ACROSS THE CWA WITH THE FRONT ON WEDNESDAY. FOR NOW WILL GO WITH THE UPPER 40S NORTH CENTRAL TO NEAR 70 IN THE FAR SOUTHEAST CORNER. TEMPERATURES WILL THEN FALL INTO THURSDAY WITH HIGHS FROM THE UPPER 30S NORTH CENTRAL TO THE 40S ELSEWHERE. THE MODELS ARE STILL IN AGREEMENT THAT AFTER THE DEEP TROUGH PASSES THROUGH THE AREA THURSDAY...IT SHOULD BE DRY UNTIL THE PASSAGE OF ANOTHER SHORTWAVE TROUGH OCCURS SUNDAY INTO MONDAY. THIS WILL BE THE NEXT CHANCE FOR SHOWERS. HIGHS FOLLOWING THE THURSDAY SYSTEM WILL REMAIN BELOW NORMAL WITH READINGS IN THE UPPER 40S AND LOW 50S FRIDAY THEN THE 60S FOR SATURDAY INTO MONDAY. FROST AND OR FREEZING TEMPERATURES REMAIN A CONCERN PRIMARILY FOR FRIDAY AND SATURDAY MORNINGS. && .AVIATION...(FOR THE 00Z TAFS THROUGH 00Z TUESDAY EVENING) ISSUED AT 626 PM CDT MON APR 15 2013 EXPECT VFR CONDITIONS THROUGH AT LEAST THE FIRST 12 HOURS OF THE TAF...AND PROBABLY THROUGH 18Z. CIGS IN THE 4K TO 6K FOOT RANGE WILL PERSIST THROUGH THE NIGHT INTO TUESDAY MORNING...BUT ARE EXPECTED TO DECREASE TO AROUND 2500 FEET DURING THE AFTERNOON. TS APPEAR POSSIBLE AFTER 10Z-12Z BUT SHOULD BE SCATTERED. TS WILL INITIALLY COME CLOSE TO TOP/FOE...BUT EVENTUALLY TS CHANCES SPREAD WEST TO MHK AS WELL. AT THIS TIME...IT APPEARS THAT SCATTERED TS POSSIBLE ALMOST ANY TIME OF DAY ON TUESDAY. && .TOP WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...BARJENBRUCH SHORT TERM...53 LONG TERM...63 AVIATION...BARJENBRUCH
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
631 PM EDT TUE APR 16 2013 .SYNOPSIS... SHOWERS AND THUNDERSTORMS ARE LIKELY TODAY AND TONIGHT AS A COLD FRONT SLIDES ACROSS THE REGION. && .NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/... JUST MADE A QUICK UPDATE TO BETTER REFLECT WARMING TEMPERATURES IN THE LOCATIONS AHEAD OF THE COLD FRONT THAT ARE SEEING BREAKS IN CLOUD COVER. ADJUSTED POP TIMING A LITTLE FOR THE OVERNIGHT HOURS BASED ON THE MOST RECENT HRRR SINCE IT SEEMS TO BE REFLECTING THE CURRENT SITUATION QUITE WELL. OTHERWISE...NO OTHER CHANGES. PREVIOUS DISCUSSION FOLLOWS... WHILE AMPLE CLOUD COVER HAS REMAINED ACROSS THE REGION TODAY...SURFACE TEMPERATURES AND DEWOPINTS OUT AHEAD OF THE COLD FRONT HAVE STILL REBOUNDED QUITE NICELY ALLOWING FOR AN INCREASE IN CAPE TO NEAR 1000J/KG FOR SOUTHERN PORTIONS OF THE REGION. THIS IS EXPECTED TO CONTINUE AND WHILE THE BETTER INSTABILITY AND SHEAR CURRENTLY DO NOT LINE UP WELL...THIS COULD CHANGE AS ANOTHER SHORTWAVE APPROACHES THE COLD FRONT AS IT GRADUALLY SAGS SOUTHWARD. GIVEN THIS...CANNOT RULE OUT A FEW THUNDERSTORMS MAINTAINING THEMSELVES TO SEVERE LEVELS. THUS...AFTER COLLABORATION WITH SURROUNDING OFFICES AND THE STORM PREDICTION CENTER...A SEVERE THUNDERSTORM WATCH HAS BEEN ISSUED THROUGH 11PM THIS EVENING. BASED ON THE MOST RECENT HRRR AND OTHER HI-RES MODELS...THE LINE OF SHOWERS SHOULD REACH THE SOUTHERN HALF OF THE REGION OVERNIGHT BEFORE THE BOUNDARY STALLS OVER SOMEWHERE ALONG THE MASON DIXON LINE. WARM NR TERM TEMPS WERE FORECAST USING A BLEND OF GUIDANCE AND THE LATEST OBSERVATION TRENDS. && .SHORT TERM /6 AM WEDNESDAY MORNING THROUGH FRIDAY/... STALLED FRONT WILL DRIFT NORTHWARD WED...BUT APPEARS TO ALMOST WASH OUT AS RIDGES STRENGTHENS OVER THE UPPER OHIO VALLEY. THE FRONT WILL BE FORCED NORTHWARD AS THE MAIN SFC LOW SWINGS OUT OF THE SOUTHERN ROCKIES AND INTO THE SOUTHERN PLAINS. THE HEIGHT RISES ARE IN RESPONSE TO A LARGE TROUGH WHICH WILL DIG INTO THE ROCKIES. WILL INCLUDE THE CHC FOR SHOWERS AND STORMS WED AS AN UPPER LEVEL WAVE WILL CREST THE TOP OF THE BUILDING RIDGE. AREA WILL LIE IN THE WARM SECTOR BY WED NIGHT AND REMAIN THERE THROUGH THU. EXPECT WED NIGHT TO REMAIN DRY WITH SCT SHOWERS/STORMS POSSIBLE THU WITH DAYTIME HEATING. UNDER SOUTHERLY FLOW...TEMPS WILL RISE ABOVE NORMAL ON THU. && .LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/... A CDFNT SHOULD BE EXITING THE RGN FRI EVE...WITH ANY SHRA/TS CHCS ENDG FRI NGT. AN UPR LVL TROF IS EXPD TO MOVE ACRS THE GT LKS RGN SAT...BUT MOISTURE IS LMTD SO KEPT FCST DRY ATTM. HIGH PRES BLDS IN SAT NGT THRU MON NGT UNTIL A CDFNT APRCHS FM THE W ON TUE WITH ANOTHER CHC FOR SHRA/TS. TEMPS SHOULD BE BLO AVG LVLS OVR THE WKEND...WITH A WRMG TREND ERLY NXT WK. && .AVIATION /00Z WEDNESDAY THROUGH SUNDAY/... COLD FRONT WILL MOVE ACROSS THE REGION THIS EVENING. THINK THAT A BRIEF PERIOD OF TSRA REMAINS POSSIBLE WITH THE FRONT AS IT PASSES. GUSTY SW WNDS LATE THIS AFTN SHOULD SHFT TO THE W AND THEN N THIS EVE AFT FROPA. MVFR CIGS WILL REMAIN A POSSIBILITY AT FKL/DUJ INTO THE EVE...OTRW GENL LOW END VFR CIGS FCST OUTSIDE OF ANY PCPN ACRS THE RGN. .OUTLOOK.../WEDNESDAY NIGHT THROUGH SUNDAY/... THE FNT WL MOVE BACK N AS A WRMFNT WED NGT INTO THU WITH BRF RESTRNS PSBL. A CDFNT WL MOVE E ACRS THE RGN FRI WITH SHRA/TS RESTRNS BEFORE HI PRES BLDS IN SAT. && .PBZ WATCHES/WARNINGS/ADVISORIES... MD...NONE. OH...NONE. PA...NONE. WV...NONE. && $$
AREA FORECAST DISCUSSION
NWS PITTSBURGH PA
431 PM EDT TUE APR 16 2013 .SYNOPSIS... SHOWERS AND THUNDERSTORMS ARE LIKELY TODAY AND TONIGHT AS A COLD FRONT SLIDES ACROSS THE REGION. && .NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/... WHILE AMPLE CLOUD COVER HAS REMAINED ACROSS THE REGION TODAY...SURFACE TEMPERATURES AND DEWOPINTS OUT AHEAD OF THE COLD FRONT HAVE STILL REBOUNDED QUITE NICELY ALLOWING FOR AN INCREASE IN CAPE TO NEAR 1000J/KG FOR SOUTHERN PORTIONS OF THE REGION. THIS IS EXPECTED TO CONTINUE AND WHILE THE BETTER INSTABILITY AND SHEAR CURRENTLY DO NOT LINE UP WELL...THIS COULD CHANGE AS ANOTHER SHORTWAVE APPROACHES THE COLD FRONT AS IT GRADUALLY SAGS SOUTHWARD. GIVEN THIS...CANNOT RULE OUT A FEW THUNDERSTORMS MAINTAINING THEMSELVES TO SEVERE LEVELS. THUS...AFTER COLLABORATION WITH SURROUNDING OFFICES AND THE STORM PREDICTION CENTER...A SEVERE THUNDERSTORM WATCH HAS BEEN ISSUED THROUGH 11PM THIS EVENING. BASED ON THE MOST RECENT HRRR AND OTHER HI-RES MODELS...THE LINE OF SHOWERS SHOULD REACH THE SOUTHERN HALF OF THE REGION OVERNIGHT BEFORE THE BOUNDARY STALLS OVER SOMEWHERE ALONG THE MASON DIXON LINE. WARM NR TERM TEMPS WERE FORECAST USING A BLEND OF GUIDANCE AND THE LATEST OBSERVATION TRENDS. && .SHORT TERM /6 AM WEDNESDAY MORNING THROUGH FRIDAY/... STALLED FRONT WILL DRIFT NORTHWARD WED...BUT APPEARS TO ALMOST WASH OUT AS RIDGES STRENGTHENS OVER THE UPPER OHIO VALLEY. THE FRONT WILL BE FORCED NORTHWARD AS THE MAIN SFC LOW SWINGS OUT OF THE SOUTHERN ROCKIES AND INTO THE SOUTHERN PLAINS. THE HEIGHT RISES ARE IN RESPONSE TO A LARGE TROUGH WHICH WILL DIG INTO THE ROCKIES. WILL INCLUDE THE CHC FOR SHOWERS AND STORMS WED AS AN UPPER LEVEL WAVE WILL CREST THE TOP OF THE BUILDING RIDGE. AREA WILL LIE IN THE WARM SECTOR BY WED NIGHT AND REMAIN THERE THROUGH THU. EXPECT WED NIGHT TO REMAIN DRY WITH SCT SHOWERS/STORMS POSSIBLE THU WITH DAYTIME HEATING. UNDER SOUTHERLY FLOW...TEMPS WILL RISE ABOVE NORMAL ON THU. && .LONG TERM /FRIDAY NIGHT THROUGH TUESDAY/... A CDFNT SHOULD BE EXITING THE RGN FRI EVE...WITH ANY SHRA/TS CHCS ENDG FRI NGT. AN UPR LVL TROF IS EXPD TO MOVE ACRS THE GT LKS RGN SAT...BUT MOISTURE IS LMTD SO KEPT FCST DRY ATTM. HIGH PRES BLDS IN SAT NGT THRU MON NGT UNTIL A CDFNT APRCHS FM THE W ON TUE WITH ANOTHER CHC FOR SHRA/TS. TEMPS SHOULD BE BLO AVG LVLS OVR THE WKEND...WITH A WRMG TREND ERLY NXT WK. && .AVIATION /20Z TUESDAY THROUGH SUNDAY/... COLD FRONT WILL MOVE ACROSS THE REGION THIS EVENING. THINK THAT A BRIEF PERIOD OF TSRA REMAINS POSSIBLE WITH THE FRONT AS IT PASSES. GUSTY SW WNDS LATE THIS AFTN SHOULD SHFT TO THE W AND THEN N THIS EVE AFT FROPA. MVFR CIGS WILL REMAIN A POSSIBILITY AT FKL/DUJ INTO THE EVE...OTRW GENL LOW END VFR CIGS FCST OUTSIDE OF ANY PCPN ACRS THE RGN. .OUTLOOK.../WEDNESDAY NIGHT THROUGH SUNDAY/... THE FNT WL MOVE BACK N AS A WRMFNT WED NGT INTO THU WITH BRF RESTRNS PSBL. A CDFNT WL MOVE E ACRS THE RGN FRI WITH SHRA/TS RESTRNS BEFORE HI PRES BLDS IN SAT. && .PBZ WATCHES/WARNINGS/ADVISORIES... MD...NONE. OH...NONE. PA...NONE. WV...NONE. && $$
AREA FORECAST DISCUSSION
NWS WAKEFIELD VA
211 PM EDT TUE APR 16 2013 .SYNOPSIS... A WEAK FRONTAL BOUNDARY WILL CROSS JUST NORTH OF THE REGION TONIGHT. OTHERWISE...HIGH PRESSURE BECOMES CENTERED OFF THE MID ATLANTIC COAST FOR MOST OF THIS WEEK. A MORE VIGOROUS COLD FRONT WILL IMPACT THE AREA FRIDAY INTO SATURDAY.. && .NEAR TERM /THROUGH TONIGHT/... OVERALL CONDITIONS IMPROVE AS CLOUDY SKIES THIS MORNING BREAK UP DURING THIS AFTN AND TEMPS WARM TOWARD 70-75 DEGREES AREAWIDE...EXCEPT AT THE BEACHES WHERE TEMPS WILL BE IN THE 60S DUE TO PERSISTENT ONSHORE FLOW. THE LOCAL WRF AND THE RAP MODELS ALL SHOW THE MOISTURE SLOW TO MIX OUT IN THE WEST IN THE 925 TO 850 MB LAYER. THEY DO SHOW THAT LEVEL WINDS SLOWLY MOVING TO SOUTHWEST AND DRYING DEVELOPING. WILL ALSO KEEP TEMPERATURES COOLER IN THE WEST INITIALLY WITH MORE CLOUD COVER. FOR TONIGHT...A COLD FRONT PASSES ACROSS NEW ENGLAND AND WILL DRAG A WEAK BOUNDARY ACROSS NWRN PORTIONS OF THE FA OVERNIGHT. THIS FEATURE WILL BRING INCREASED CLOUDS TO THIS AREA WITH PARTLY CLOUDY SKIES FARTHER TO THE SE. LOW TEMPS WILL RUN ABOUT 5 DEGREES ABOVE NORMAL AS CLOUD COVER INSULATES THE ATMOSPHERE TONIGHT. EXPECT LOWS IN THE MID TO UPPER 50S REGIONWIDE (LOW TO MID 50S IMMEDIATE COAST). && .SHORT TERM /WEDNESDAY THROUGH FRIDAY/... WED/WED NIGHT...RELATIVELY FLAT UPPER LEVEL RIDGING AND SW FLOW OVER THE TN VALLEY AND SPINE OF THE APPALACHIANS WILL ALLOW MOISTURE AND WEAK SHORTWAVE ENERGY TO MOVE AROUND THE PERIPHERY OF THE UPPER RIDGE DURING THE AFTN/EVENING. THE DEVELOPMENT OF A LEE TROUGH IS ALSO POSSIBLE AS THE FRONT FROM TUE NIGHT STALLS ACROSS SE VA/NE NC. UNLIKE MOST LEE TROUGHS THAT TEND TO DEVELOP OVER THE ERN PIEDMONT...THIS ONE IS EXPECTED TO TAKE ON MORE OF A POSITIVELY TILTED ORIENTATION (ENE TO WSW). INCREASING TEMPS AND DEWPOINTS DURING THE DAY WILL CREATE ENOUGH LOW-LEVEL INSTABILITY FOR LIGHT SHOWERS TO BE POSSIBLE NORTH OF THE TROUGH AXIS. HOWEVER...WEAK DYNAMICS AND VERY LIGHT WINDS BELOW 500 MB WILL LIMIT THUNDER POTENTIAL TO A SLIGHT CHANCE IN THE AFTN/EVENING. EXPECT A NICE WARM-UP WITH HIGHS IN THE LOWER 80S FOR MOST AREAS...IN THE MID-UPPER 70S FOR THE IMMEDIATE COAST...AND IN THE UPPER 60S NEAR OCEAN CITY MD. ANY SHOWERS THAT DEVELOP SHOULD DISSIPATE QUICKLY AROUND SUNSET DUE TO THE LOSS OF DAYTIME HEATING AND BECAUSE OF THE WEAK DYNAMICS ALREADY PRESENT. MOSTLY CLOUDY SKIES WILL ONCE AGAIN HAMPER LOW TEMPS FROM DROPPING TO THEIR FULL POTENTIAL. LOWS SHOULD GENERALLY BE AROUND 60 (MID-UPPER 50S IMMEDIATE COAST). THU/THU NIGHT...THE MID AND UPPER LEVEL RIDGE AXES MOVE OFFSHORE ON THU. SW FLOW ALOFT WILL RESULT IN WAA TAKING PLACE THUS ALLOWING HIGH TEMPS TO WARM A FEW MORE DEGREES AS COMPARED TO WED. AN APPROACHING COLD FRONT MOVING ACROSS THE CTRL U.S. WILL CAUSE THE SFC PRESSURE GRADIENT TO TIGHTEN...THEREFORE GUSTS OF 20-25 MPH ARE ANTICIPATED DURING THE AFTN. ASIDE FROM BREEZY CONDITIONS...THU WILL BE A RATHER NICE DAY ACROSS THE AREA. THE VIGOROUS COLD FRONT CONTINUES TO DIG INTO THE MIDWEST THU NIGHT...ACTING TO SLOW ITS EWD PROGRESSION INTO THE MID ATLANTIC REGION. SFC WINDS WILL BECOME MORE SLY THU NIGHT AND REINFORCE ONGOING WAA PROCESSES. THE COMBINATION OF WAA AND INCREASING HIGH CLOUDS FROM THE APPROACHING SYSTEM WILL ALLOW LOW TEMPS TO RUN ABOUT 10-15 DEGREES ABOVE SEASONAL NORMALS. LOWS SHOULD GENERALLY BE IN THE LOWER 60S (55 TO 60 IMMEDIATE COAST). FRI...THE APPROACHING (AND VIGOROUS) COLD FRONT WILL CONTINUE TO APPROACH THE MID ATLANTIC REGION ON FRI. SLY SFC WINDS WILL INCREASE FURTHER WITH GUSTS OF 25-30 MPH LIKELY AS THE PRESSURE GRADIENT TIGHTENS EVEN MORE. THERE ARE SOME INDICATIONS THAT PRECIPITATION GENERATION MAY NOT OCCUR UNTIL FRI AFTN...BUT HAVE KEPT THE MORNING FORECAST INTACT FOR NOW WITH CHC SHOWERS FOR THE ERN PIEDMONT AND SCHC SHOWERS AS FAR AS THE MID ATLANTIC COAST. FOR THE AFTN...LEE TROUGH DEVELOPMENT IS ANTICIPATED DUE TO TEMPERATURE DIFFERENCES AHEAD OF AND BEHIND THE FRONT. ALSO... ISENTROPIC SFCS INDICATE 40-50 KT OF SW FLOW WITH THE BEST MOISTURE IN THE PIEDMONT DURING THE AFTN. DUE TO THE SLOWER NATURE OF DIGGING SYSTEMS...THE FRONT SHOULD BE DELAYED AND BEST PRECIP CHANCES SHOULD OCCUR IN THE PIEDMONT THU AFTN ALONG THE LEE TROUGH AXIS WITH MORE SHOWERS DEVELOPING FARTHER EAST DURING THE EVENING. FAVORABLE THERMAL PROFILES AND UNIDIRECTIONAL WIND SHEAR...IN ADDITION TO DYNAMIC SUPPORT ALOFT...WILL SUPPORT THUNDERSTORMS WITH THE POTENTIAL FOR DAMAGING WIND GUSTS ON FRI AFTN INTO FRI NIGHT. PWATS ARE ALSO PROGGED TO REACH 1.50 INCHES WHICH WILL RESULT IN MODERATE TO HEAVY RAINFALL. THIS SYSTEM BEARS CLOSE MONITORING SINCE IT IS TOO EARLY TO NARROW DOWN THE FINER DETAILS. && .LONG TERM /FRIDAY NIGHT THROUGH MONDAY/... WILL INCREASE POPS QUICKLY FROM WEST TO EAST BY FRIDAY EVENING INTO SATURDAY MORNING AS THE FRONT MOVES THROUGH. EXPECTING THE PRECIP TO END ACROSS THE LOCAL AREA SATURDAY AFTERNOON. LOWS FRIDAY NIGHT MAINLY IN THE 50S. COOLER SATURDAY WITH HIGHS IN THE 60S. HIGH PRESSURE BRIEFLY BUILDS IN SUNDAY FOR DRY WX. THERE IS THE POSSIBILITY OF INCREASED ONSHORE FLOW NEXT MONDAY WITH A COASTAL FRONT/INVERTED TROUGH BACKING INTO THE AREA. WILL ADVERTISE SOME LOW POPS BY NEXT MONDAY FOR NOW AND KEEPS HIGH TEMPS IN THE 60S NEXT SUNDAY/MONDAY. && .AVIATION /18Z TUESDAY THROUGH SUNDAY/... TAF SITES WILL HAVE BKN/OVC CIGS 4 TO 7K FT AGL WITH SOME POTENTIAL LOWERING TO MVFR LEVELS (3K FT AGL) IN WESTERN PORTIONS OF THE CWA. HIGH PRESSURE MOVES BACK INTO THE REGION WITH LOW LEVEL MOISTURE BRINGING A CHANCE FOR PATCHY FOG/LOW CIGS BY EARLY WED MORNING. ISOLATED TO WIDELY SCATTERED SHRA/TSRA WILL BE POSSIBLE WED LATE AFTN/EARLY EVENING (GREATEST CHC FOR THIS AT KRIC). COULD AGAIN SEE SOME PATCHY FOG/LOW CLOUDS EARLY THU. OTHERWISE...MAINLY VFR UNTIL THE FRONT ARRIVES FRI AFTN INTO EARLY SAT...BRINGING NUMEROUS SHRA/ISOLATED TO SCATTERED TSRA AND A PERIOD OF IFR CONDITIONS. && .MARINE... HAVE ADDED A FEW MORE ZONES INTO THE SCA HEADLINES...AS SEAS REMAIN 6-8 FT ACRS SE VA AND NE NC COASTAL WATERS (3-4 FT AT THE MOUTH OF THE BAY)...AND ARE SLOWLY INCREASING FARTHER NORTH. FOR COASTAL WATERS N OF PARRAMORE WILL START THE SCA BY 7 AM...AND SEAS SHOULD AVG 4-6 FT ACRS THESE AREAS THROUGH THE EVENING. WHILE MUCH OF THIS IS DUE TO SWELL RATHER THAN WIND HAVE DECIDED TO KEEP IT SMALL CRAFT ADVSY AS OPPOSED TO SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS TO AVOID CONFUSION W/ MULTIPLE HEADLINES. OTHERWISE...WEAK LOW PRESSURE IS STILL SITUATED OFF THE SC COAST WITH HIGH PRESSURE CENTERED OFF THE NEW ENGLAND COAST AND THE RESULTANT FLOW BETWEEN THESE TWO FEATURES CONTINUES TO PRODUCE E/SE WINDS. WIND SPEEDS TODAY ARE NOT EXPECTED TO GET MUCH ABOVE 15 KT SO DO NOT ANTICIPATE ANY HEADLINES OUTSIDE OF THE COASTAL WATERS AND MOUTH OF THE BAY FOR TODAY. IT MAY BE CLOSE IN THE BAY BY THIS EVENING AS SE FLOW INCREASES SOMEWHAT AS IT OFTEN DOES IN THE EVENING (WHILE THEY WEAKEN OVER LAND). FOR NOW HAVE KEPT THEM CAPPED AT 15 KT. WINDS WILL THEN TURN MORE TO SW OVERNIGHT BEFORE BECOMING RATHER LIGHT ON WED. THIS SHOULD ALLOW SEAS TO SUBSIDE BELOW 5 FT. WINDS INCREASE ON THU...AND ESPECIALLY THU NIGHT THROUGH FRI AS PRESSURE GRADIENT TIGHTENS UP AHEAD OF THE APPROACHING COLD FRONT. SCA CONDITIONS ARE LIKELY THU NIGHT THROUGH FRI NIGHT. && .AKQ WATCHES/WARNINGS/ADVISORIES... MD...NONE. NC...NONE. VA...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 7 PM EDT THIS EVENING FOR ANZ634- 654-656-658. SMALL CRAFT ADVISORY UNTIL 10 PM EDT THIS EVENING FOR ANZ650- 652. && $$ SYNOPSIS...BMD NEAR TERM...BMD/JAB SHORT TERM...BMD LONG TERM...JDM AVIATION...LKB/DAP MARINE...LKB
AREA FORECAST DISCUSSION
NWS WAKEFIELD VA
1008 AM EDT TUE APR 16 2013 .SYNOPSIS... A WEAK FRONTAL BOUNDARY WILL CROSS JUST NORTH OF THE REGION TONIGHT. OTHERWISE...HIGH PRESSURE BECOMES CENTERED OFF THE MID ATLANTIC COAST FOR MOST OF THIS WEEK. A MORE VIGOROUS COLD FRONT WILL IMPACT THE AREA FRIDAY INTO SATURDAY.. && .NEAR TERM /THROUGH TONIGHT/... OVERALL CONDITIONS IMPROVE AS CLOUDY SKIES THIS MORNING BREAK UP DURING THIS AFTN AND TEMPS WARM TOWARD 70-75 DEGREES AREAWIDE...EXCEPT AT THE BEACHES WHERE TEMPS WILL BE IN THE 60S DUE TO PERSISTENT ONSHORE FLOW. THE LOCAL WRF AND THE RAP MODELS ALL SHOW THE MOISTURE SLOW TO MIX OUT IN THE WEST IN THE 925 TO 850 MB LAYER. THEY DO SHOW THAT LEVEL WINDS SLOWLY MOVING TO SOUTHWEST AND DRYING DEVELOPING. WILL ALSO KEEP TEMPERATURES COOLER IN THE WEST INITIALLY WITH MORE CLOUD COVER. FOR TONIGHT...A COLD FRONT PASSES ACROSS NEW ENGLAND AND WILL DRAG A WEAK BOUNDARY ACROSS NWRN PORTIONS OF THE FA OVERNIGHT. THIS FEATURE WILL BRING INCREASED CLOUDS TO THIS AREA WITH PARTLY CLOUDY SKIES FARTHER TO THE SE. LOW TEMPS WILL RUN ABOUT 5 DEGREES ABOVE NORMAL AS CLOUD COVER INSULATES THE ATMOSPHERE TONIGHT. EXPECT LOWS IN THE MID TO UPPER 50S REGIONWIDE (LOW TO MID 50S IMMEDIATE COAST). && .SHORT TERM /WEDNESDAY THROUGH FRIDAY/... WED/WED NIGHT...RELATIVELY FLAT UPPER LEVEL RIDGING AND SW FLOW OVER THE TN VALLEY AND SPINE OF THE APPALACHIANS WILL ALLOW MOISTURE AND WEAK SHORTWAVE ENERGY TO MOVE AROUND THE PERIPHERY OF THE UPPER RIDGE DURING THE AFTN/EVENING. THE DEVELOPMENT OF A LEE TROUGH IS ALSO POSSIBLE AS THE FRONT FROM TUE NIGHT STALLS ACROSS SE VA/NE NC. UNLIKE MOST LEE TROUGHS THAT TEND TO DEVELOP OVER THE ERN PIEDMONT...THIS ONE IS EXPECTED TO TAKE ON MORE OF A POSITIVELY TILTED ORIENTATION (ENE TO WSW). INCREASING TEMPS AND DEWPOINTS DURING THE DAY WILL CREATE ENOUGH LOW-LEVEL INSTABILITY FOR LIGHT SHOWERS TO BE POSSIBLE NORTH OF THE TROUGH AXIS. HOWEVER...WEAK DYNAMICS AND VERY LIGHT WINDS BELOW 500 MB WILL LIMIT THUNDER POTENTIAL TO A SLIGHT CHANCE IN THE AFTN/EVENING. EXPECT A NICE WARM-UP WITH HIGHS IN THE LOWER 80S FOR MOST AREAS...IN THE MID-UPPER 70S FOR THE IMMEDIATE COAST...AND IN THE UPPER 60S NEAR OCEAN CITY MD. ANY SHOWERS THAT DEVELOP SHOULD DISSIPATE QUICKLY AROUND SUNSET DUE TO THE LOSS OF DAYTIME HEATING AND BECAUSE OF THE WEAK DYNAMICS ALREADY PRESENT. MOSTLY CLOUDY SKIES WILL ONCE AGAIN HAMPER LOW TEMPS FROM DROPPING TO THEIR FULL POTENTIAL. LOWS SHOULD GENERALLY BE AROUND 60 (MID-UPPER 50S IMMEDIATE COAST). THU/THU NIGHT...THE MID AND UPPER LEVEL RIDGE AXES MOVE OFFSHORE ON THU. SW FLOW ALOFT WILL RESULT IN WAA TAKING PLACE THUS ALLOWING HIGH TEMPS TO WARM A FEW MORE DEGREES AS COMPARED TO WED. AN APPROACHING COLD FRONT MOVING ACROSS THE CTRL U.S. WILL CAUSE THE SFC PRESSURE GRADIENT TO TIGHTEN...THEREFORE GUSTS OF 20-25 MPH ARE ANTICIPATED DURING THE AFTN. ASIDE FROM BREEZY CONDITIONS...THU WILL BE A RATHER NICE DAY ACROSS THE AREA. THE VIGOROUS COLD FRONT CONTINUES TO DIG INTO THE MIDWEST THU NIGHT...ACTING TO SLOW ITS EWD PROGRESSION INTO THE MID ATLANTIC REGION. SFC WINDS WILL BECOME MORE SLY THU NIGHT AND REINFORCE ONGOING WAA PROCESSES. THE COMBINATION OF WAA AND INCREASING HIGH CLOUDS FROM THE APPROACHING SYSTEM WILL ALLOW LOW TEMPS TO RUN ABOUT 10-15 DEGREES ABOVE SEASONAL NORMALS. LOWS SHOULD GENERALLY BE IN THE LOWER 60S (55 TO 60 IMMEDIATE COAST). FRI...THE APPROACHING (AND VIGOROUS) COLD FRONT WILL CONTINUE TO APPROACH THE MID ATLANTIC REGION ON FRI. SLY SFC WINDS WILL INCREASE FURTHER WITH GUSTS OF 25-30 MPH LIKELY AS THE PRESSURE GRADIENT TIGHTENS EVEN MORE. THERE ARE SOME INDICATIONS THAT PRECIPITATION GENERATION MAY NOT OCCUR UNTIL FRI AFTN...BUT HAVE KEPT THE MORNING FORECAST INTACT FOR NOW WITH CHC SHOWERS FOR THE ERN PIEDMONT AND SCHC SHOWERS AS FAR AS THE MID ATLANTIC COAST. FOR THE AFTN...LEE TROUGH DEVELOPMENT IS ANTICIPATED DUE TO TEMPERATURE DIFFERENCES AHEAD OF AND BEHIND THE FRONT. ALSO... ISENTROPIC SFCS INDICATE 40-50 KT OF SW FLOW WITH THE BEST MOISTURE IN THE PIEDMONT DURING THE AFTN. DUE TO THE SLOWER NATURE OF DIGGING SYSTEMS...THE FRONT SHOULD BE DELAYED AND BEST PRECIP CHANCES SHOULD OCCUR IN THE PIEDMONT THU AFTN ALONG THE LEE TROUGH AXIS WITH MORE SHOWERS DEVELOPING FARTHER EAST DURING THE EVENING. FAVORABLE THERMAL PROFILES AND UNIDIRECTIONAL WIND SHEAR...IN ADDITION TO DYNAMIC SUPPORT ALOFT...WILL SUPPORT THUNDERSTORMS WITH THE POTENTIAL FOR DAMAGING WIND GUSTS ON FRI AFTN INTO FRI NIGHT. PWATS ARE ALSO PROGGED TO REACH 1.50 INCHES WHICH WILL RESULT IN MODERATE TO HEAVY RAINFALL. THIS SYSTEM BEARS CLOSE MONITORING SINCE IT IS TOO EARLY TO NARROW DOWN THE FINER DETAILS. && .LONG TERM /FRIDAY NIGHT THROUGH MONDAY/... WILL INCREASE POPS QUICKLY FROM WEST TO EAST BY FRIDAY EVENING INTO SATURDAY MORNING AS THE FRONT MOVES THROUGH. EXPECTING THE PRECIP TO END ACROSS THE LOCAL AREA SATURDAY AFTERNOON. LOWS FRIDAY NIGHT MAINLY IN THE 50S. COOLER SATURDAY WITH HIGHS IN THE 60S. HIGH PRESSURE BRIEFLY BUILDS IN SUNDAY FOR DRY WX. THERE IS THE POSSIBILITY OF INCREASED ONSHORE FLOW NEXT MONDAY WITH A COASTAL FRONT/INVERTED TROUGH BACKING INTO THE AREA. WILL ADVERTISE SOME LOW POPS BY NEXT MONDAY FOR NOW AND KEEPS HIGH TEMPS IN THE 60S NEXT SUNDAY/MONDAY. && .AVIATION /14Z TUESDAY THROUGH SATURDAY/... E/SE ONSHORE FLOW PREVAILS EARLY THIS MORNING...WITH VARIABLY CLOUDY SKIES ACRS THE AREA. IN GENERAL...TAF SITES WILL HAVE BKN/OVC CIGS 4 TO 7K FT AGL WITH SOME POTENTIAL LOWERING TO MVFR LEVELS (2-3K FT AGL) BETWEEN 09-12Z. MODELS STRUGGLING TO HANDLE ONSHORE FLOW AND POSSIBLE IFR CIGS OVER THE REGION. THE HIGHEST CONFIDENCE FOR IFR CIGS EXPECTED TO REMAIN OVER THE PIEDMONT WWD INTO THE BLUE RIDGE AND HIGHER TERRAIN (WHICH WOULD NOT AFFECT TAF SITES). SOME PATCHY FOG WILL BE POSSIBLE INLAND IF SKIES CLEAR OUT...BUT THIS LOOKS TO BE UNLIKELY AT KRIC SO WILL NOT HAVE ANY MVFR/IFR VSBYS. OVERALL CONDITIONS IMPROVE TODAY AS HIGH PRESSURE MOVES BACK INTO THE REGION THROUGH WED NIGHT. LOW LEVEL MOISTURE WILL BRING AT LEAST A LOW CHANCE FOR PATCHY FOG/LOW CIGS BY EARLY WED MORNING...WITH ISOLATED TO WIDELY SCATTERED SHRA/TSRA POSSIBLE WED LATE AFTN/EARLY EVENING (GREATEST CHC FOR THIS AT KRIC). COULD AGAIN SEE SOME PATCHY FOG/LOW CLOUDS EARLY THU. OTHERWISE...MAINLY VFR UNTIL THE FRONT ARRIVES FRI AFTN INTO EARLY SAT...BRINGING NUMEROUS SHRA/ISOLATED TO SCATTERED TSRA AND A PERIOD OF IFR CONDITIONS. && .MARINE... HAVE ADDED A FEW MORE ZONES INTO THE SCA HEADLINES...AS SEAS REMAIN 6-8 FT ACRS SE VA AND NE NC COASTAL WATERS (3-4 FT AT THE MOUTH OF THE BAY)...AND ARE SLOWLY INCREASING FARTHER NORTH. FOR COASTAL WATERS N OF PARRAMORE WILL START THE SCA BY 7 AM...AND SEAS SHOULD AVG 4-6 FT ACRS THESE AREAS THROUGH THE EVENING. WHILE MUCH OF THIS IS DUE TO SWELL RATHER THAN WIND HAVE DECIDED TO KEEP IT SMALL CRAFT ADVSY AS OPPOSED TO SMALL CRAFT ADVISORY FOR HAZARDOUS SEAS TO AVOID CONFUSION W/ MULTIPLE HEADLINES. OTHERWISE...WEAK LOW PRESSURE IS STILL SITUATED OFF THE SC COAST WITH HIGH PRESSURE CENTERED OFF THE NEW ENGLAND COAST AND THE RESULTANT FLOW BETWEEN THESE TWO FEATURES CONTINUES TO PRODUCE E/SE WINDS. WIND SPEEDS TODAY ARE NOT EXPECTED TO GET MUCH ABOVE 15 KT SO DO NOT ANTICIPATE ANY HEADLINES OUTSIDE OF THE COASTAL WATERS AND MOUTH OF THE BAY FOR TODAY. IT MAY BE CLOSE IN THE BAY BY THIS EVENING AS SE FLOW INCREASES SOMEWHAT AS IT OFTEN DOES IN THE EVENING (WHILE THEY WEAKEN OVER LAND). FOR NOW HAVE KEPT THEM CAPPED AT 15 KT. WINDS WILL THEN TURN MORE TO SW OVERNIGHT BEFORE BECOMING RATHER LIGHT ON WED. THIS SHOULD ALLOW SEAS TO SUBSIDE BELOW 5 FT. WINDS INCREASE ON THU...AND ESPECIALLY THU NIGHT THROUGH FRI AS PRESSURE GRADIENT TIGHTENS UP AHEAD OF THE APPROACHING COLD FRONT. SCA CONDITIONS ARE LIKELY THU NIGHT THROUGH FRI NIGHT. && .AKQ WATCHES/WARNINGS/ADVISORIES... MD...NONE. NC...NONE. VA...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 7 PM EDT THIS EVENING FOR ANZ634- 654-656-658. SMALL CRAFT ADVISORY UNTIL 10 PM EDT THIS EVENING FOR ANZ650- 652. && $$ SYNOPSIS...BMD NEAR TERM...BMD/JAB SHORT TERM...BMD LONG TERM...JDM AVIATION...LKB MARINE...LKB
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
437 PM EDT TUE APR 16 2013 .SHORT TERM...(THIS EVENING THROUGH WEDNESDAY) ISSUED AT 436 PM EDT TUE APR 16 2013 WV IMAGERY AND RUC ANALYSIS INDICATED A MID/UPPER LEVEL TROUGH FROM NRN QUEBEC THROUGH JAMES BAY INTO NRN ONTARIO WAS DEPARTING TO THE EAST. UPSTREAM...SW FLOW PREVAILED THROUGH THE PLAINS AHEAD OF A TROUGH FROM THE NRN ROCKIES THROUGH THE GREAT BASIN. WITH CONFLUENT FLOW WITH QVECTOR DIV AND SUBSIDENCE OVER THE NRN GREAT LAKES...THE SCT FLURRIES HAD DIMINISHED THIS AFTERNOON. AS HIGH PRES BUILDS INTO NRN ONTARIO TONIGHT BRINGING ENE ACYC FLOW INTO UPPER MI AND DAYTIME HEATING FADES...EXPECT THAT WINDS WILL DIMINISH AND CLOUDS WILL THIN OUT ENOUGH FOR TEMPS TO DROP INTO THE 20S. AS THE WRN TROUGH EDGES TO THE EAST AND A SFC-850 MB TROUGH DEVELOPS FROM THE SRN PLAINS INTO THE UPPER MS VALLEY...WAA AND MOISTURE ADVECTION WILL INCREASE QUICKLY BY WED AFTERNOON. THE INITIAL AREA OF PCPN IS EXPECTED INTO THE WEST...WHERE 295K-300K ISENTROPIC LIFT IS STRONGEST. GIVEN THE DRY ERLY FLOW AS THE HIGH GRADUALLY MOVES EAST THROUGH NRN ONTARIO...THE SLOWER PROGRESSION OF PCPN INTO UPPER...PER NAM...WAS PREFERRED COMPARED TO THE GFS/ECMWF. EXPECT ENOUGH OF A LINGERING WARM LOWER LAYER FOR MOSTLY RAIN AT THE ONSET OF MAINLY LIGHT PCPN AS AFTERNOON TEMPS CLIMB INTO THE 40F TO 45F RANGE. .LONG TERM...(WEDNESDAY NIGHT THROUGH TUESDAY) ISSUED AT 436 PM EDT TUE APR 16 2013 MAIN ATTENTION FOR THE LONG TERM PORTION OF THE FORECAST ARE THE TWO WAVES OF PRECIPITATION ASSOCIATED WITH ENERGY AND LOW PRESSURE SYSTEMS EXITING FROM THE UPPER TROUGH CURRENTLY MOVING THROUGH THE WESTERN CONUS. FIRST WAVE WILL BE INFLUENCING THE AREA AT THE START OF THE LONG TERM PERIOD WILL BE ASSOCIATED WITH SHORTWAVE ENERGY EJECTING AHEAD OF THE TROUGH EXPECTED TO BE IN THE CENTRAL ROCKIES. AT THE SURFACE...A LOW CENTERED IN WESTERN OKLAHOMA AND THE PANHANDLE OF TEXAS WILL BEGIN ELONGATING A TROUGH NORTHEAST INT HE MID MISSISSIPPI VALLEY ON WEDNESDAY AFTERNOON AND THEN NORTHEAST INTO NORTHERN LAKE MICHIGAN BY 12Z THURSDAY. WITH THE STRONG MID LEVEL FORCING ASSOCIATED WITH 925-700MB WARM AIR ADVECTION AND LIKELY CONVECTION ON THE EAST SIDE OF THE TROUGH...WOULD EXPECT THE HEAVIEST PRECIPITATION TO BE JUST TO THE SOUTHEAST OF THE CWA OR BRUSH THE SOUTHEAST PART OF THE CWA. BUT...WITH THE AREA UNDER THE RIGHT REAR OF THE UPPER JET AND ENOUGH OVERRIDING FLOW WITH THAT WARM AIR ADVECTION AND ISENTROPIC ASCENT ON THE 280-300K SFCS...STILL THINK THAT THERE WILL BE ENOUGH FORCING FOR MODERATE PRECIPITATION ACROSS MUCH OF THE CWA. GENERAL MODEL CONSENSUS OF 0.50-0.80 INCH SEEMS REASONABLE FOR MUCH OF THE AREA...WITH VALUES APPROACHING AN INCH ALONG THE LAKE MICHIGAN SHORELINE. THIS TRICKY PART OF THIS FORECAST IS WHAT AMOUNT OF THE PRECIP WILL FALL AS RAIN OVER THE WESTERN HALF OF THE CWA DUE TO THE ELEVATED WARM LAYER. THERE CONTINUES TO BE SOME DISCREPANCY IN THE AMOUNT OF WARM AIR THAT MOVES OVER THE CENTRAL CWA AND HOW FAR WEST THAT MOVES. THINK THE FAR WESTERN CWA WILL LIKELY SEE MAINLY SNOW /FROM KCMX TO KIWD/...BUT COULD SEE A BRIEF PERIOD OF FREEZING RAIN OVERNIGHT. THE AREA BETWEEN THERE AND A LINE FROM MARQUETTE TO IRON MOUNTAIN IS THE TRICKY AREA...SINCE THERE WILL LIKELY BE ENOUGH WARM AIR TO MELT THE SNOW ALOFT. THEN PRECIP TYPE COMES DOWN TO SURFACE TEMPERATURES...SINCE 925MB TEMPS ARE WELL BELOW FREEZING. WILL CONTINUE TO MENTION MAINLY FREEZING RAIN IN THAT AREA...WITH SOME MENTION OF SNOW. ALL IN ALL...APPEARS THAT THIS WILL LIKELY BE A SOLID ADVISORY FOR THE WESTERN HALF OF THE CWA AND THERE IS SOME CONCERN FOR DECENT ICE ACCUMULATION DEPENDING ON WHAT THE SURFACE TEMPS ARE. THIS ENERGY WILL SHIFT NORTHEAST ON THURSDAY MORNING AND WITH THE 850MB FLOW BECOMING MORE SOUTHWEST...WOULD EXPECT THE PRECIPITATION TO WEAKEN HEADING INTO THE AFTERNOON. NEXT SYSTEM TO AFFECT THE AREA WILL BE AS THE UPPER TROUGH LIFTS TO THE NORTHEAST AND MOVES TOWARDS THE UPPER GREAT LAKES ON THURSDAY NIGHT INTO FRIDAY. THIS WILL INTENSIFY A LOW ALONG THE LINGERING SURFACE TROUGH AND THEN LIKELY TRACK TOWARDS THE STRAITS OF MACKINAC BY 12Z FRIDAY. THE MAIN CONCERN FOR WIDESPREAD PRECIPITATION FOR THE AREA IS THE TRACK/LOCATION OF THE DRY SLOT SURGING NORTHEAST ON THURSDAY NIGHT INTO FRIDAY. THERE ARE STILL SOME DIFFERENCES IN THE LOW TRACK WITH THE NAM/GEM...SO OPTED TO FOLLOW THE MORE CONSISTENT IDEA OF THE GFS/ECMWF FOR THE FORECAST. LATEST INDICATIONS IN THE MODELS THAT THE DRY SLOT WILL AFFECT THE CENTRAL/EASTERN CWA...BETWEEN THE DEFORMATION PRECIPITATION AFFECTING THE WESTERN CWA AND THE CONVECTION AND HEAVY RAIN AFFECTING LOWER MICHIGAN AHEAD OF THE COLD FRONT. THUS...WOULD EXPECT THE HEAVIEST PRECIPITATION TO OCCUR OVER THE WESTERN THIRD OF THE CWA THURSDAY NIGHT INTO FRIDAY...WITH THE REST OF THE AREA SEEING LIGHTER PRECIPITATION. BASED OFF THE THERMAL PROFILE...THAT ALSO SEEMS TO BE THE LOCATION OF THE RAIN/SNOW/MIXED PRECIPITATION LINE...LARGELY STRETCHING FROM KIMT/KSAW. THE CONCERN FOR THE CENTRAL CWA WILL BE THE EXPECTED AREA OF SUBFREEZING TEMPERATURES BELOW 875MB WHICH WOULD LEAD TO THE RAIN FREEZING WHEN IT GETS TO THE SURFACE. OUT WEST...THE PRECIPITATION WILL LIKELY START OUT AS FREEZING RAIN AS THE WARM NOSE ROTATES THROUGH AND THEN TRANSITION TO SNOW FROM WEST TO EAST. WHEN COMBINED WITH THE NORTHERLY FLOW OFF LAKE SUPERIOR WITH 850MB TEMPS FALLING TO -10C ON FRIDAY SHOULD SEE LAKE ENHANCEMENT REALLY INCREASE AMOUNTS OVER GOGEBIC/ONTONAGON COUNTIES THROUGH THE DAY ON FRIDAY. WITH THAT AREA SEEING BOTH THE DEFORMATION PRECIPITATION AND THE LAKE ENHANCEMENT...CURRENT EXPECTATION WOULD BE WARNING SNOWFALL AMOUNTS AND SOME LOCATIONS COULD SEE SOME SIGNIFICANT SNOWFALL AMOUNTS FOR MID-LATE APRIL. IN ADDITION TO THE SNOW...STRONG NORTHERLY WINDS FROM THE KEWEENAW THROUGH GOGEBIC COUNTY WILL LEAD TO NEAR BLIZZARD CONDITIONS EVEN THOUGH THE SNOW WILL LIKELY BE ON THE WETTER SIDE INITIALLY. WILL CONTINUE THE SPS FOR THE WEDNESDAY NIGHT THROUGH FRIDAY PERIOD...SINCE I FEEL THAT ENCOMPASSES THE ENTIRE SYSTEM WELL AND SINCE THE THE MOST SIGNIFICANT EVENT WILL BE THE SECOND SYSTEM. COULD HAVE DONE A LONG PERIOD WATCH TO COVER BOTH EVENTS...BUT SINCE THE FIRST WAVE SEEMS TO BE MORE OF AN ADVISORY SITUATION AND THEN A BRIEF BREAK ON THURSDAY AFTERNOON...WASN`T SURE IF THAT WOULD COME ACROSS WELL WITH A LONG TERM WATCH HEADLINE. EXPECT THE LAKE ENHANCED SNOW TO CONTINUE INTO FRIDAY NIGHT BUT WILL QUICKLY COME TO AN END ON SATURDAY AS THE UPPER TROUGH LIFTS TO THE NORTHEAST AND SURFACE HIGH PRESSURE BUILDS OVER THE AREA. THIS SHOULD LEAD TO A NICE BUT COOL START TO THE WEEKEND...WITH HIGHS ONLY REACHING THE 30S IN MOST LOCATIONS. THEN AS THE HIGH AND UPPER RIDGE SHIFTS TO THE EAST ON SUNDAY...THE NEXT WAVE FROM THE PACIFIC NORTHWEST WILL BE APPROACHING THE AREA FOR SUNDAY NIGHT AND CONTINUING INTO MONDAY NIGHT AND TUESDAY. THERE CONTINUES TO BE SOME DIFFERENCES IN THE DETERMINISTIC MODELS AND THERE ENSEMBLE MEANS...BUT THE GENERAL IDEA OF THE UPPER TROUGH AND COLD FRONT MOVING THROUGH THE AREA DURING THAT TIME SEEMS REASONABLE. THE AREA WILL LIKELY SEE A BRIEF WARM UP FOR SUNDAY INTO MONDAY...BACK INTO THE 40S...BUT THEN COOL TO BELOW NORMAL VALUES BEHIND THE COLD FRONT ON TUESDAY. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z WEDNESDAY AFTERNOON) ISSUED AT 131 PM EDT TUE APR 16 2013 ABUNDANT 925-850 MB MOISTURE ALONG WITH DAYTIME HEATING SUPPORTED BKN CIGS JUST ABOVE 3K FT AT IWD/SAW AND AROUND 2K FT AT CMX. EXPECT MVFR CIGS WILL LIFT/SCATTER OUT TOWARD EVENING WITH CONTINUED MIXING AND SLIGHTLY DRIER AIR MOVING IN. VFR CONDITIONS ARE EXPECTED TONIGHT. ALTHOUGH THERE IS UNCERTAINTY WITH THE AMOUNT OF 925-900 MB MOISTURE ACROSS NORTHERN UPPER MI WED MORNING...PER NAM/GFS...A MENTION OF MVFR CIGS WAS INCLUDED. && .MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE) ISSUED AT 436 PM EDT TUE APR 16 2013 WINDS WILL STAY BELOW 30 KNOTS THROUGH THU BEFORE INCREASING OUT OF THE NORTH THURSDAY NIGHT INTO FRIDAY NIGHT WHEN NORTH GALES ARE LIKELY AS A DEEP LOW PRESSURE SYSTEM MOVES TOWARD NORTHERN LAKE MICHIGAN AND EAST UPPER MICHIGAN. THERE IS THE POTENTIAL FOR HIGHER END GALES WITH THIS SYSTEM IN THE 40 TO 45 KNOT RANGE. THE WINDS WILL DIMINISH FRI NIGHT INTO SAT AS THE LOW MOVES QUICKLY TO THE NORTHEAST OF THE REGION AND HIGH PRES BUILDS IN FROM THE WEST. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... NONE. LAKE SUPERIOR... NONE. LAKE MICHIGAN... NONE. && $$ SHORT TERM...JLB LONG TERM...SRF AVIATION...JLB MARINE...JLB
AREA FORECAST DISCUSSION
NWS DETROIT/PONTIAC MI
219 PM EDT TUE APR 16 2013 .AVIATION... //DISCUSSION... THE FRONTAL BOUNDARY HAS SLIPPED SOUTHEAST OF THE AREA ACROSS FAR EASTERN PORTIONS OF LAKE ERIE AND OHIO. BUILDING SURFACE HIGH PRESSURE SOUTH OF HUDSON BAY REGION TONIGHT WILL ALLOW ANTICYCLONIC FLOW TO BUILD SOUTHWARD INTO THE GREAT LAKES. THIS SHOULD RESULT IN AN EVENING INLAND RELEASE OF THE LAKE/MARINE AIRMASS...SUBSEQUENTLY DRYING OUT THE NEAR SURFACE ENVIRONMENT. MEANWHILE...A SAMPLE OF THE HI RESOLUTION MODELS ARE SUGGESTING SOME NORTHERN FRINGE SHOWERS AND MIDLEVEL MOISTURE WILL LIFT/CLIP INTO THE SOUTHERN TAF SITES AFTER 21Z...PERSISTING INTO THE EVENING. THIS IS A LOW CONFIDENCE FORECAST AS THOSE SOLUTIONS ARE EXHIBITING SOME CONVECTIVE START UP ISSUES. WILL MONITOR AND AMEND THE TAFS MORE PESSIMISTIC AS NEEDED. //DTW THRESHOLD THREATS... * LOW CONFIDENCE IN LIGHT PRECIPITATION POTENTIAL THIS EVENING. * HIGH CONFIDENCE CEILINGS WILL FALL BELOW 5000FT AFTER 10Z WEDNESDAY. && .PREV DISCUSSION...ISSUED 613 AM EDT TUE APR 16 2013 UPDATE... LOW LEVEL FGEN...NOT PICKED UP BY THE 00Z MODELS...WAS PICKED UP BY THE 06Z MODELS AND CENTERED AROUND H9. DESPITE PICKING THIS LOW LEVEL FGEN UP THE NWP MODELS CONTINUE TO UNDERESTIMATE THE CURRENT ACTIVITY ABOUT TO SWEEP THROUGH EXTREME SOUTHEASTERN MICHIGAN. HOWEVER THE RECENT 3KM HRRR MODEL PICKS THIS UP NICELY AND SWEEPS THE MODERATE SHOWERS THROUGH THE AREA BETWEEN 10-13Z THIS MORNING. WITH MODEST INSTABILITY AND INTERSPERSED LIGHTNING STRIKES WILL ADD THUNDER TO THE MUCH RAISED POPS ACROSS THE SOUTHERN CWA THIS MORNING AS THE COLD FRONT CONTINUES MARCHING SOUTHEASTWARD. AT THIS TIME THE REST OF THE FORECAST LOOKS FINE GOING FORWARD AS THE ACTIVITY TO THE NORTH HAS SIGNIFICANTLY DECREASED AS ADVERTISED. PREV DISCUSSION...ISSUED 334 AM EDT TUE APR 16 2013 SHORT TERM...THIS MORNING THROUGH TONIGHT AN AREA OF SHOWERS STRETCHING FROM CENTRAL LAKE HURON BACK TO SOUTHERN LAKE MICHIGAN ALONG A SLOWLY MOVING COLD FRONT AND COINCIDENT WITH FGEN IN THE H9-H7 LAYER WILL SLOWLY MOVE SOUTHEAST DURING THE MORNING HOURS. HOWEVER MODEL CROSS SECTIONS SHOW THE FGEN WILL ELONGATE...WEAKEN AND LIFT NORTH AS THE MORNING WEARS ON. DEEP MOISTURE ASSOCIATED WITH THE FRONT WILL LIFT NORTH WITH THE MAIN FGEN BAND...AS THE FRONT ITSELF BECOMES DIFFUSE TEMPERATURE-WISE. THESE FACTORS DO NOT LEAD TO A HIGH DEGREE OF CONFIDENCE THAT RAIN SHOWERS WILL ACTUALLY MAKE IT ALL THE WAY THROUGH THE SOUTHERN AND EASTERN CWA THIS MORNING AS THE FRONT TRACKS TOWARDS THE NORTHERN OHIO VALLEY. GIVEN THE WEAKENING DYNAMICS AND DECREASED AVAILABLE MOISTURE WILL NOT DRAG THE CATEGORICAL POPS ALL THE THROUGH THE SOUTHEASTERN CWA THIS MORNING AS THE FRONT MOVES SOUTH...AND INSTEAD LEAVE LIKELY POPS ACROSS THESE AREAS PER THE PREVIOUS FORECAST. WITH THE FRONT OVER THE NORTHERN OHIO VALLEY POPS WILL BE RATHER LOW THIS AFTERNOON AND THIS EVENING AS THE MAIN DYNAMICS STAY TO THE SOUTH. WITH A BETTER HANDLE ON THE PLACEMENT OF THE FRONT WILL TAKE THE CHANCY POPS FROM THE AFTERNOON AND PLACE THEM IN THE EVENING HOURS AS THE SURGE NORTHWARD OF THE MID-LEVEL FRONT AND INCREASED FGEN OVER THE SOUTHERN GREAT LAKES DOES NOT MAKE IT INTO THE SOUTHEASTERN MICHIGAN UNTIL LATER TONIGHT. THEREFORE WILL REFINE THE WINDOW FOR LIKELY POPS TO AFTER MIDNIGHT WHEN THIS BETTER FORCING COMES BACK INTO THE CWA. WITH MEAGER DYNAMICS AND NOT MUCH INSTABILITY TO SPEAK OF WILL CONTINUE TO LEAVE THUNDER OUT OF THE FORECAST THROUGH TONIGHT. WITH THE PUSH OF COLD AIR BEHIND THE COLD FRONT BECOMING MORE DIFFUSE...HIGH TEMPERATURES TODAY SHOULD BE ABLE TO GET INTO THE UPPER 50S TO LOWER 60S. NORTHEAST WINDS OVERNIGHT WILL BRING COOLER AIR IN FROM THE GREAT LAKES...WITH LOWS RANGING FROM THE MID 30S ACROSS THE NORTH TO THE LOW TO MID 40S ACROSS THE SOUTH. LONG TERM... HIGHLY AMPLIFIED PATTERN DEVELOPING...AS UPPER LEVEL ENERGY OVER PACIFIC NORTHWEST EXTENDING SOUTH INTO THE GREAT BASIN CONTINUES TO CONSOLIDATE AND ORGANIZE. THE 00Z MODEL TRENDS ARE DEEPER WITH THE SYSTEM COMING OUT OF THE CENTRAL CONUS/MIDWEST THURSDAY...AND IT NOW APPEARS FRIDAY MORNING WILL BE MILD AND RAINY BEFORE THE STRONG LOW LEVEL COLD ADVECTION SENDS 850 MB TEMPS BELOW ZERO BY 00Z SATURDAY. THURSDAY/THURSDAY NIGHT LOOKS VERY WET ...AS IMPRESSIVE LOW LEVEL JET (50 TO 55 KNOTS AT 850 MB) EXTENDS FROM TEXAS ALL THE WAY UP TO THE CENTRAL GREAT LAKES...ALLOWING COPIOUS AMOUNTS OF GULF OF MEXICO MOISTURE TO STREAM NORTHWARD. STILL HAVE SOME CONCERN FOR SEVERE WEATHER ON THURSDAY WITH THE IMPRESSIVE WIND FIELDS...AS 00Z GFS EVEN ADVERTISING SURFACE BASED CAPES IN SOLIDLY EXCESS OF 1000 J/KG THERE IS A STRONG POSSIBILITY A FLOOD WATCH WILL BE NEEDED FOR THURSDAY-FRIDAY MORNING TIME FRAME AS THIS DYNAMIC SYSTEM AND MOISTURE LADEN (PW VALUES TO AROUND 1.5 INCHES) IMPACTS THE GREAT LAKES REGION. THE FORECAST IS COMPLICATED ON THURSDAY DUE TO THE FACT RIGHT ENTRANCE REGION FORCING OF THE UPPER LEVEL JET IS DISPLACED WELL TO THE NORTH OF LOWER MICHIGAN...SO NOT A GUARANTEE IS GOING TO RAIN ACROSS THE FAR SOUTHEAST AS WE REMAIN UNDER THE INFLUENCE OF THE DEPARTING UPPER LEVEL RIDGE. ON THE FLIP SIDE...IF THE ALL BLEND SURFACE DEW PTS OF 62-63 DEGREES VERIFY...THAT IS CLIMATOLOGY NEAR RECORD TERRITORY...AND HARD TO BELIEVE THE ENHANCED ISENTROPIC ASSENT WILL NOT GENERATE SHOWERS AND THUNDERSTORMS WITH THE MORE THAN ADEQUATE INSTABILITY. NEED TO MENTION THE POTENTIAL FOR STRONG WIND POP RIGHT BEHIND THE POWERFUL COLD FRONT ON FRIDAY...AS 6 HR RISE/FALL PRESSURE COUPLET IS INTENSIFYING THROUGH THE DAY...AND LOOKS TO BE AT LEAST 20 MB. WITH THE STOUT LOW LEVEL COLD ADVECTION/SUBSIDENCE COMING THROUGH DURING THE PEAK HEATING OF THE DAY...MIXING INTO THE 45 TO 50 KNOT WINDS AT 850 MB DOES NOT LOOK TO BE MUCH OF A CHALLENGE...AND WILL HIGHLIGHT THE POTENTIAL OF WIND GUSTS OF 45 MPH OR GREATER IN HWO. QUIET BY COOL WEATHER FOR THE WEEKEND...AS 850 MB TEMPS STILL PROGGED TO BE RUNNING AROUND -10 C TO START THE DAY ON SATURDAY...BUT MODIFYING INTO THE MID SINGLE NUMBERS DURING THE AFTERNOON...AND NEGATIVE LOW SINGLE NUMBERS FOR SUNDAY AFTERNOON...PER 00Z EURO. MARINE... A SLOWLY MOVING COLD FRONT WILL FLIP THE WIND DIRECTION TO WNW ACROSS ALL OF THE CENTRAL GREAT LAKES REGION THIS MORNING. WINDS WILL THEN VEER TO THE NORTHEAST TONIGHT THEN TO AN EASTERLY DIRECTION ON WEDNESDAY. HOWEVER SHORT DURATION FETCH AND A LACK OF STRONGER WINDS WILL LIMIT SIGNIFICANT WAVE HEIGHTS TO 5 FEET OR LESS ACROSS AREA WATERS THROUGH WEDNESDAY. PERSISTENT EASTERLY FLOW WILL LEAD TO A BUILD UP OF WAVES ACROSS THE CENTRAL GREAT LAKES WEDNESDAY NIGHT...WITH SMALL CRAFT HEADLINES A POSSIBILITY FOR ALL NEARSHORE AREAS SAVE FOR INNER SAGINAW BAY. WILL ISSUE APPROPRIATE HEADLINES AS NECESSARY AS THE EVENT DRAWS CLOSER. && .DTX WATCHES/WARNINGS/ADVISORIES... MI...NONE. LAKE HURON...NONE. LAKE ST CLAIR...NONE. MI WATERS OF LAKE ERIE...NONE. && $$ AVIATION.....CB UPDATE.......KURIMSKI SHORT TERM...KURIMSKI LONG TERM....SF MARINE.......KURIMSKI YOU CAN OBTAIN YOUR LATEST NATIONAL WEATHER SERVICE FORECASTS ONLINE AT WWW.WEATHER.GOV/DETROIT (ALL LOWER CASE).
AREA FORECAST DISCUSSION
NWS DETROIT/PONTIAC MI
721 AM EDT TUE APR 16 2013 .AVIATION... //DISCUSSION... A COLD FRONT HAS CLEARED THE TAF SITES OVERNIGHT. AN AREA OF SHOWERS FROM PTK SOUTH TO THE METRO AIRPORTS WILL SLOWLY CLEAR OUT OVER THE NEXT FEW HOURS...LEAVING LOW LEVEL MOISTURE AND CLOUDS IN PLACE. BEFORE THE SHOWERS EXIT EAST SOME THUNDERSTORMS ARE POSSIBLE AT THE METRO AIRPORTS THROUGH 13Z AS LINGERING INSTABILITY CLEARS OUT OF THE REGION. THE LOW CLOUDS WILL ERODE AS THE DAY WEARS ON AS LOW LEVEL MOISTURE IS SCOURED OUT BY DRIER AIR ADVECTING IN WITH A RIDGE OF HIGH PRESSURE. THIS PROCESS IS ALREADY UNDERWAY ACROSS NORTHERN LOWER MICHIGAN AS CONDITIONS HAVE BECOME VFR. ALTHOUGH MODELS BRING SHOWERS BACK OVER THE TAF SITES LATE TONIGHT...CONFIDENCE IN SHOWERS IS NOT HIGH ENOUGH TO PUT INTO THE TAFS AT THIS POINT. FOR DTW...THUNDERSTORMS SHOULD CLEAR THE AIRPORT AROUND 13Z WITH LINGERING SHOWERS THROUGH 15Z AS THE COLD FRONT CONTINUES MARCHING SOUTHEAST. //DTW THRESHOLD THREATS... * HIGH CONFIDENCE THUNDERSTORMS WILL OCCUR EARLY THIS MORNING. * HIGH CONFIDENCE CEILINGS WILL BE BELOW 5000 FT THIS MORNING. && .PREV DISCUSSION...ISSUED 613 AM EDT TUE APR 16 2013 UPDATE... LOW LEVEL FGEN...NOT PICKED UP BY THE 00Z MODELS...WAS PICKED UP BY THE 06Z MODELS AND CENTERED AROUND H9. DESPITE PICKING THIS LOW LEVEL FGEN UP THE NWP MODELS CONTINUE TO UNDERESTIMATE THE CURRENT ACTIVITY ABOUT TO SWEEP THROUGH EXTREME SOUTHEASTERN MICHIGAN. HOWEVER THE RECENT 3KM HRRR MODEL PICKS THIS UP NICELY AND SWEEPS THE MODERATE SHOWERS THROUGH THE AREA BETWEEN 10-13Z THIS MORNING. WITH MODEST INSTABILITY AND INTERSPERSED LIGHTNING STRIKES WILL ADD THUNDER TO THE MUCH RAISED POPS ACROSS THE SOUTHERN CWA THIS MORNING AS THE COLD FRONT CONTINUES MARCHING SOUTHEASTWARD. AT THIS TIME THE REST OF THE FORECAST LOOKS FINE GOING FORWARD AS THE ACTIVITY TO THE NORTH HAS SIGNIFICANTLY DECREASED AS ADVERTISED. PREV DISCUSSION...ISSUED 334 AM EDT TUE APR 16 2013 SHORT TERM...THIS MORNING THROUGH TONIGHT AN AREA OF SHOWERS STRETCHING FROM CENTRAL LAKE HURON BACK TO SOUTHERN LAKE MICHIGAN ALONG A SLOWLY MOVING COLD FRONT AND COINCIDENT WITH FGEN IN THE H9-H7 LAYER WILL SLOWLY MOVE SOUTHEAST DURING THE MORNING HOURS. HOWEVER MODEL CROSS SECTIONS SHOW THE FGEN WILL ELONGATE...WEAKEN AND LIFT NORTH AS THE MORNING WEARS ON. DEEP MOISTURE ASSOCIATED WITH THE FRONT WILL LIFT NORTH WITH THE MAIN FGEN BAND...AS THE FRONT ITSELF BECOMES DIFFUSE TEMPERATURE-WISE. THESE FACTORS DO NOT LEAD TO A HIGH DEGREE OF CONFIDENCE THAT RAIN SHOWERS WILL ACTUALLY MAKE IT ALL THE WAY THROUGH THE SOUTHERN AND EASTERN CWA THIS MORNING AS THE FRONT TRACKS TOWARDS THE NORTHERN OHIO VALLEY. GIVEN THE WEAKENING DYNAMICS AND DECREASED AVAILABLE MOISTURE WILL NOT DRAG THE CATEGORICAL POPS ALL THE THROUGH THE SOUTHEASTERN CWA THIS MORNING AS THE FRONT MOVES SOUTH...AND INSTEAD LEAVE LIKELY POPS ACROSS THESE AREAS PER THE PREVIOUS FORECAST. WITH THE FRONT OVER THE NORTHERN OHIO VALLEY POPS WILL BE RATHER LOW THIS AFTERNOON AND THIS EVENING AS THE MAIN DYNAMICS STAY TO THE SOUTH. WITH A BETTER HANDLE ON THE PLACEMENT OF THE FRONT WILL TAKE THE CHANCY POPS FROM THE AFTERNOON AND PLACE THEM IN THE EVENING HOURS AS THE SURGE NORTHWARD OF THE MID-LEVEL FRONT AND INCREASED FGEN OVER THE SOUTHERN GREAT LAKES DOES NOT MAKE IT INTO THE SOUTHEASTERN MICHIGAN UNTIL LATER TONIGHT. THEREFORE WILL REFINE THE WINDOW FOR LIKELY POPS TO AFTER MIDNIGHT WHEN THIS BETTER FORCING COMES BACK INTO THE CWA. WITH MEAGER DYNAMICS AND NOT MUCH INSTABILITY TO SPEAK OF WILL CONTINUE TO LEAVE THUNDER OUT OF THE FORECAST THROUGH TONIGHT. WITH THE PUSH OF COLD AIR BEHIND THE COLD FRONT BECOMING MORE DIFFUSE...HIGH TEMPERATURES TODAY SHOULD BE ABLE TO GET INTO THE UPPER 50S TO LOWER 60S. NORTHEAST WINDS OVERNIGHT WILL BRING COOLER AIR IN FROM THE GREAT LAKES...WITH LOWS RANGING FROM THE MID 30S ACROSS THE NORTH TO THE LOW TO MID 40S ACROSS THE SOUTH. LONG TERM... HIGHLY AMPLIFIED PATTERN DEVELOPING...AS UPPER LEVEL ENERGY OVER PACIFIC NORTHWEST EXTENDING SOUTH INTO THE GREAT BASIN CONTINUES TO CONSOLIDATE AND ORGANIZE. THE 00Z MODEL TRENDS ARE DEEPER WITH THE SYSTEM COMING OUT OF THE CENTRAL CONUS/MIDWEST THURSDAY...AND IT NOW APPEARS FRIDAY MORNING WILL BE MILD AND RAINY BEFORE THE STRONG LOW LEVEL COLD ADVECTION SENDS 850 MB TEMPS BELOW ZERO BY 00Z SATURDAY. THURSDAY/THURSDAY NIGHT LOOKS VERY WET ...AS IMPRESSIVE LOW LEVEL JET (50 TO 55 KNOTS AT 850 MB) EXTENDS FROM TEXAS ALL THE WAY UP TO THE CENTRAL GREAT LAKES...ALLOWING COPIOUS AMOUNTS OF GULF OF MEXICO MOISTURE TO STREAM NORTHWARD. STILL HAVE SOME CONCERN FOR SEVERE WEATHER ON THURSDAY WITH THE IMPRESSIVE WIND FIELDS...AS 00Z GFS EVEN ADVERTISING SURFACE BASED CAPES IN SOLIDLY EXCESS OF 1000 J/KG THERE IS A STRONG POSSIBILITY A FLOOD WATCH WILL BE NEEDED FOR THURSDAY-FRIDAY MORNING TIME FRAME AS THIS DYNAMIC SYSTEM AND MOISTURE LADEN (PW VALUES TO AROUND 1.5 INCHES) IMPACTS THE GREAT LAKES REGION. THE FORECAST IS COMPLICATED ON THURSDAY DUE TO THE FACT RIGHT ENTRANCE REGION FORCING OF THE UPPER LEVEL JET IS DISPLACED WELL TO THE NORTH OF LOWER MICHIGAN...SO NOT A GUARANTEE IS GOING TO RAIN ACROSS THE FAR SOUTHEAST AS WE REMAIN UNDER THE INFLUENCE OF THE DEPARTING UPPER LEVEL RIDGE. ON THE FLIP SIDE...IF THE ALL BLEND SURFACE DEW PTS OF 62-63 DEGREES VERIFY...THAT IS CLIMATOLOGY NEAR RECORD TERRITORY...AND HARD TO BELIEVE THE ENHANCED ISENTROPIC ASSENT WILL NOT GENERATE SHOWERS AND THUNDERSTORMS WITH THE MORE THAN ADEQUATE INSTABILITY. NEED TO MENTION THE POTENTIAL FOR STRONG WIND POP RIGHT BEHIND THE POWERFUL COLD FRONT ON FRIDAY...AS 6 HR RISE/FALL PRESSURE COUPLET IS INTENSIFYING THROUGH THE DAY...AND LOOKS TO BE AT LEAST 20 MB. WITH THE STOUT LOW LEVEL COLD ADVECTION/SUBSIDENCE COMING THROUGH DURING THE PEAK HEATING OF THE DAY...MIXING INTO THE 45 TO 50 KNOT WINDS AT 850 MB DOES NOT LOOK TO BE MUCH OF A CHALLENGE...AND WILL HIGHLIGHT THE POTENTIAL OF WIND GUSTS OF 45 MPH OR GREATER IN HWO. QUIET BY COOL WEATHER FOR THE WEEKEND...AS 850 MB TEMPS STILL PROGGED TO BE RUNNING AROUND -10 C TO START THE DAY ON SATURDAY...BUT MODIFYING INTO THE MID SINGLE NUMBERS DURING THE AFTERNOON...AND NEGATIVE LOW SINGLE NUMBERS FOR SUNDAY AFTERNOON...PER 00Z EURO. MARINE... A SLOWLY MOVING COLD FRONT WILL FLIP THE WIND DIRECTION TO WNW ACROSS ALL OF THE CENTRAL GREAT LAKES REGION THIS MORNING. WINDS WILL THEN VEER TO THE NORTHEAST TONIGHT THEN TO AN EASTERLY DIRECTION ON WEDNESDAY. HOWEVER SHORT DURATION FETCH AND A LACK OF STRONGER WINDS WILL LIMIT SIGNIFICANT WAVE HEIGHTS TO 5 FEET OR LESS ACROSS AREA WATERS THROUGH WEDNESDAY. PERSISTENT EASTERLY FLOW WILL LEAD TO A BUILD UP OF WAVES ACROSS THE CENTRAL GREAT LAKES WEDNESDAY NIGHT...WITH SMALL CRAFT HEADLINES A POSSIBILITY FOR ALL NEARSHORE AREAS SAVE FOR INNER SAGINAW BAY. WILL ISSUE APPROPRIATE HEADLINES AS NECESSARY AS THE EVENT DRAWS CLOSER. && .DTX WATCHES/WARNINGS/ADVISORIES... MI...NONE. LAKE HURON...NONE. LAKE ST CLAIR...NONE. MI WATERS OF LAKE ERIE...NONE. && $$ AVIATION.....KURIMSKI UPDATE.......KURIMSKI SHORT TERM...KURIMSKI LONG TERM....SF MARINE.......KURIMSKI YOU CAN OBTAIN YOUR LATEST NATIONAL WEATHER SERVICE FORECASTS ONLINE AT WWW.WEATHER.GOV/DETROIT (ALL LOWER CASE).
AREA FORECAST DISCUSSION
NWS DETROIT/PONTIAC MI
613 AM EDT TUE APR 16 2013 .UPDATE... LOW LEVEL FGEN...NOT PICKED UP BY THE 00Z MODELS...WAS PICKED UP BY THE 06Z MODELS AND CENTERED AROUND H9. DESPITE PICKING THIS LOW LEVEL FGEN UP THE NWP MODELS CONTINUE TO UNDERESTIMATE THE CURRENT ACTIVITY ABOUT TO SWEEP THROUGH EXTREME SOUTHEASTERN MICHIGAN. HOWEVER THE RECENT 3KM HRRR MODEL PICKS THIS UP NICELY AND SWEEPS THE MODERATE SHOWERS THROUGH THE AREA BETWEEN 10-13Z THIS MORNING. WITH MODEST INSTABILITY AND INTERSPERSED LIGHTNING STRIKES WILL ADD THUNDER TO THE MUCH RAISED POPS ACROSS THE SOUTHERN CWA THIS MORNING AS THE COLD FRONT CONTINUES MARCHING SOUTHEASTWARD. AT THIS TIME THE REST OF THE FORECAST LOOKS FINE GOING FORWARD AS THE ACTIVITY TO THE NORTH HAS SIGNIFICANTLY DECREASED AS ADVERTISED. && .PREV DISCUSSION...ISSUED 334 AM EDT TUE APR 16 2013 SHORT TERM...THIS MORNING THROUGH TONIGHT AN AREA OF SHOWERS STRETCHING FROM CENTRAL LAKE HURON BACK TO SOUTHERN LAKE MICHIGAN ALONG A SLOWLY MOVING COLD FRONT AND COINCIDENT WITH FGEN IN THE H9-H7 LAYER WILL SLOWLY MOVE SOUTHEAST DURING THE MORNING HOURS. HOWEVER MODEL CROSS SECTIONS SHOW THE FGEN WILL ELONGATE...WEAKEN AND LIFT NORTH AS THE MORNING WEARS ON. DEEP MOISTURE ASSOCIATED WITH THE FRONT WILL LIFT NORTH WITH THE MAIN FGEN BAND...AS THE FRONT ITSELF BECOMES DIFFUSE TEMPERATURE-WISE. THESE FACTORS DO NOT LEAD TO A HIGH DEGREE OF CONFIDENCE THAT RAIN SHOWERS WILL ACTUALLY MAKE IT ALL THE WAY THROUGH THE SOUTHERN AND EASTERN CWA THIS MORNING AS THE FRONT TRACKS TOWARDS THE NORTHERN OHIO VALLEY. GIVEN THE WEAKENING DYNAMICS AND DECREASED AVAILABLE MOISTURE WILL NOT DRAG THE CATEGORICAL POPS ALL THE THROUGH THE SOUTHEASTERN CWA THIS MORNING AS THE FRONT MOVES SOUTH...AND INSTEAD LEAVE LIKELY POPS ACROSS THESE AREAS PER THE PREVIOUS FORECAST. WITH THE FRONT OVER THE NORTHERN OHIO VALLEY POPS WILL BE RATHER LOW THIS AFTERNOON AND THIS EVENING AS THE MAIN DYNAMICS STAY TO THE SOUTH. WITH A BETTER HANDLE ON THE PLACEMENT OF THE FRONT WILL TAKE THE CHANCY POPS FROM THE AFTERNOON AND PLACE THEM IN THE EVENING HOURS AS THE SURGE NORTHWARD OF THE MID-LEVEL FRONT AND INCREASED FGEN OVER THE SOUTHERN GREAT LAKES DOES NOT MAKE IT INTO THE SOUTHEASTERN MICHIGAN UNTIL LATER TONIGHT. THEREFORE WILL REFINE THE WINDOW FOR LIKELY POPS TO AFTER MIDNIGHT WHEN THIS BETTER FORCING COMES BACK INTO THE CWA. WITH MEAGER DYNAMICS AND NOT MUCH INSTABILITY TO SPEAK OF WILL CONTINUE TO LEAVE THUNDER OUT OF THE FORECAST THROUGH TONIGHT. WITH THE PUSH OF COLD AIR BEHIND THE COLD FRONT BECOMING MORE DIFFUSE...HIGH TEMPERATURES TODAY SHOULD BE ABLE TO GET INTO THE UPPER 50S TO LOWER 60S. NORTHEAST WINDS OVERNIGHT WILL BRING COOLER AIR IN FROM THE GREAT LAKES...WITH LOWS RANGING FROM THE MID 30S ACROSS THE NORTH TO THE LOW TO MID 40S ACROSS THE SOUTH. LONG TERM... HIGHLY AMPLIFIED PATTERN DEVELOPING...AS UPPER LEVEL ENERGY OVER PACIFIC NORTHWEST EXTENDING SOUTH INTO THE GREAT BASIN CONTINUES TO CONSOLIDATE AND ORGANIZE. THE 00Z MODEL TRENDS ARE DEEPER WITH THE SYSTEM COMING OUT OF THE CENTRAL CONUS/MIDWEST THURSDAY...AND IT NOW APPEARS FRIDAY MORNING WILL BE MILD AND RAINY BEFORE THE STRONG LOW LEVEL COLD ADVECTION SENDS 850 MB TEMPS BELOW ZERO BY 00Z SATURDAY. THURSDAY/THURSDAY NIGHT LOOKS VERY WET ...AS IMPRESSIVE LOW LEVEL JET (50 TO 55 KNOTS AT 850 MB) EXTENDS FROM TEXAS ALL THE WAY UP TO THE CENTRAL GREAT LAKES...ALLOWING COPIOUS AMOUNTS OF GULF OF MEXICO MOISTURE TO STREAM NORTHWARD. STILL HAVE SOME CONCERN FOR SEVERE WEATHER ON THURSDAY WITH THE IMPRESSIVE WIND FIELDS...AS 00Z GFS EVEN ADVERTISING SURFACE BASED CAPES IN SOLIDLY EXCESS OF 1000 J/KG THERE IS A STRONG POSSIBILITY A FLOOD WATCH WILL BE NEEDED FOR THURSDAY-FRIDAY MORNING TIME FRAME AS THIS DYNAMIC SYSTEM AND MOISTURE LADEN (PW VALUES TO AROUND 1.5 INCHES) IMPACTS THE GREAT LAKES REGION. THE FORECAST IS COMPLICATED ON THURSDAY DUE TO THE FACT RIGHT ENTRANCE REGION FORCING OF THE UPPER LEVEL JET IS DISPLACED WELL TO THE NORTH OF LOWER MICHIGAN...SO NOT A GUARANTEE IS GOING TO RAIN ACROSS THE FAR SOUTHEAST AS WE REMAIN UNDER THE INFLUENCE OF THE DEPARTING UPPER LEVEL RIDGE. ON THE FLIP SIDE...IF THE ALL BLEND SURFACE DEW PTS OF 62-63 DEGREES VERIFY...THAT IS CLIMATOLOGY NEAR RECORD TERRITORY...AND HARD TO BELIEVE THE ENHANCED ISENTROPIC ASSENT WILL NOT GENERATE SHOWERS AND THUNDERSTORMS WITH THE MORE THAN ADEQUATE INSTABILITY. NEED TO MENTION THE POTENTIAL FOR STRONG WIND POP RIGHT BEHIND THE POWERFUL COLD FRONT ON FRIDAY...AS 6 HR RISE/FALL PRESSURE COUPLET IS INTENSIFYING THROUGH THE DAY...AND LOOKS TO BE AT LEAST 20 MB. WITH THE STOUT LOW LEVEL COLD ADVECTION/SUBSIDENCE COMING THROUGH DURING THE PEAK HEATING OF THE DAY...MIXING INTO THE 45 TO 50 KNOT WINDS AT 850 MB DOES NOT LOOK TO BE MUCH OF A CHALLENGE...AND WILL HIGHLIGHT THE POTENTIAL OF WIND GUSTS OF 45 MPH OR GREATER IN HWO. QUIET BY COOL WEATHER FOR THE WEEKEND...AS 850 MB TEMPS STILL PROGGED TO BE RUNNING AROUND -10 C TO START THE DAY ON SATURDAY...BUT MODIFYING INTO THE MID SINGLE NUMBERS DURING THE AFTERNOON...AND NEGATIVE LOW SINGLE NUMBERS FOR SUNDAY AFTERNOON...PER 00Z EURO. MARINE... A SLOWLY MOVING COLD FRONT WILL FLIP THE WIND DIRECTION TO WNW ACROSS ALL OF THE CENTRAL GREAT LAKES REGION THIS MORNING. WINDS WILL THEN VEER TO THE NORTHEAST TONIGHT THEN TO AN EASTERLY DIRECTION ON WEDNESDAY. HOWEVER SHORT DURATION FETCH AND A LACK OF STRONGER WINDS WILL LIMIT SIGNIFICANT WAVE HEIGHTS TO 5 FEET OR LESS ACROSS AREA WATERS THROUGH WEDNESDAY. PERSISTENT EASTERLY FLOW WILL LEAD TO A BUILD UP OF WAVES ACROSS THE CENTRAL GREAT LAKES WEDNESDAY NIGHT...WITH SMALL CRAFT HEADLINES A POSSIBILITY FOR ALL NEARSHORE AREAS SAVE FOR INNER SAGINAW BAY. WILL ISSUE APPROPRIATE HEADLINES AS NECESSARY AS THE EVENT DRAWS CLOSER. && .AVIATION...ISSUED 1149 PM EDT MON APR 15 2013 //DISCUSSION... A COLD FRONT NOW OVER MBS WILL SLOWLY ADVANCE ACROSS SE MI EARLY THIS MORNING...PASSING THROUGH METRO DETROIT AROUND 09Z. A REGION OF SHOWERS WILL OCCUR ALONG AND IN THE WAKE OF THIS COLD FRONT. THE ADDED LOW LEVEL MOISTURE WILL RAPIDLY LOWER CEILINGS TO MVFR WITH SOME IFR CONDITIONS POSSIBLE IN THE IMMEDIATE POST FRONTAL AIRMASS. THE FRONTAL PASSAGE WILL ALSO BE MARKED BY AN ABRUPT SHIFT IN THE WINDS TO THE W-NW. CONDITIONS ARE EXPECTED TO IMPROVE MARKEDLY LATE TUES MORNING AS DRY AIR FUNNELS IN FROM THE WEST. FOR DTW...MORE SIGNIFICANT LOWERING OF CEILINGS AND SHOWERS WILL HOLD OFF UNTIL 09 TO 11Z GIVEN THE LATE ARRIVAL OF THE COLD FRONT. //DTW THRESHOLD THREATS... * HIGH CONFIDENCE CEILINGS WILL BE BELOW 5000 FT TUESDAY MORNING. && .DTX WATCHES/WARNINGS/ADVISORIES... MI...NONE. LAKE HURON...NONE. LAKE ST CLAIR...NONE. MI WATERS OF LAKE ERIE...NONE. && $$ UPDATE.......KURIMSKI AVIATION.....SC SHORT TERM...KURIMSKI LONG TERM....SF MARINE.......KURIMSKI YOU CAN OBTAIN YOUR LATEST NATIONAL WEATHER SERVICE FORECASTS ONLINE AT WWW.WEATHER.GOV/DETROIT (ALL LOWER CASE).
AREA FORECAST DISCUSSION
NWS MARQUETTE MI
116 AM EDT TUE APR 16 2013 .SHORT TERM...(THIS EVENING THROUGH TUESDAY) ISSUED AT 420 PM EDT MON APR 15 2013 12Z RAOBS/LATEST WV IMAGERY AND RUC ANALYSIS SHOW CLOSED UPR TROF STRETCHING FM MN THRU THE PAC NW UPSTREAM OF UPR RDG OVER THE ERN CONUS. SHRTWV THAT CAUSED WINTRY MIX OF PCPN SUN INTO THIS MRNG IS LIFTING NEWD THRU MN ON THE ERN FLANK OF THE UPR TROF AXIS. DRY SLOT ON THE ERN FLANK OF THIS DISTURBANCE HAS ADVECTED MUCH DRIER MID LVL AIR OVER UPR MI WITH SW H7 WINDS UP TO 73 KTS AS SHOWN ON THE 12Z GRB RAOB. SINCE WARM CONVEYOR BELT MSTR HAS ALSO SHIFTED TO THE E... THE CWA IS PCPN FREE THIS AFTN. RETURN OF SUNSHINE UNDER THE DRY SLOTTING OVER THE W AND CENTRAL HAS CAUSED TEMPS TO RECOVER TO MORE SEASONABLE LVLS. OVER THE E...LO CLDS HAVE BEEN MORE PERSISTENT WITH SSW LLVL FLOW OFF THE CHILLY LK MI WATERS AND LLVL MSTR SHOWN ON THE 12Z GRB RAOB. BKN SC HAS ALSO DVLPD OVER THE W AS DAYTIME HEATING HAS DESTABILIZED LLVL LAPSE RATES WITH INFLUX OF LOWER H85 TEMPS AND ARRIVAL OF MOISTER LLVL AIR DEPICTED ON THE 12Z MPX RAOB. TNGT...SHRTWV/SFC LO IN MN ARE PROGGED TO SHIFT NEWD THRU NW ONTARIO. ALTHOUGH SUPPORTING DEEP LYR QVECTOR CNVGC/DEEPER MSTR WL SLIDE TO THE NW OF UPR MI...THERE MAY BE ENUF MOISTENING OVER THE W WITH THE SLOW ARRIVAL OF COLDER AIR TO JUSTIFY RETAINING FCST OF SCHC POPS IN THAT AREA...ESPECIALLY OVERNGT WITH A WSHFT TO AN UPSLOPE W COMPONENT COINCIDENT WITH LO PRES TROF PASSAGE TO THE S OF LO MOVING THRU NW ONTARIO. ALTHOUGH THERE MAY BE MORE SC OVER THE CNTRL AS WELL...THE TRANSITION TO A MORE W WIND SHOULD AID CLRG OVER THE E. TUE...LO PRES TROF ON THE SW FLANK OF DEPARTING SHRTWV/SFC LO TOWARD JAMES BAY WL CROSS UPR MI BY EARLY AFTN. ALTHOUGH THERE WL LIKELY BE QUITE A BIT OF SC IN THE MOIST CYC W-SW SHIFTING NW FLOW...SHARP INVRN NEAR H8 SHOWN ON FCST SDNGS IN THE ABSENCE OF ANY UPR SUPPORT WL SQUASH POPS AWAY FM THE W...WHERE UPSLOPE FLOW MIGHT GENERATE A FEW -SHSN IN THE MRNG. AS THE LLVL FLOW TRENDS MORE ACYC DURING THE AFTN FOLLOWING THE TROF PASSAGE AND SE OF HI PRES BLDG TOWARD NW ONTARIO...THE SC MAY TEND TO BREAK UP IN THE AFTN...ESPECIALLY DOWNWIND OF LK SUP WITH SPRING STABILIZATION IN THE AFTN OFF THE WATER. DEEP MIXING TO H8-85 WL SUPPORT MAX TEMPS APRCHG 50 OVER THE SCENTRAL WITH DOWNSLOPE NW FLOW. AREAS NEAR LK SUP WL BE COOLER. .LONG TERM...(TUESDAY NIGHT THROUGH MONDAY) ISSUED AT 451 PM EDT MON APR 15 2013 THERE ARE A COUPLE OF PERIODS OF CONCERN IN THIS LONG TERM PERIOD. THE FIRST WILL PUSH IN FROM THE SOUTHWEST WEDNESDAY EVENING THROUGH THURSDAY MORNING...WITH A SECONDARY SURGE OF MOISTURE SLIDING ACROSS UPPER MICHIGAN THURSDAY NIGHT INTO FRIDAY. LATE THIS WEEKEND INTO EARLY NEXT WEEK MAY ALSO END UP BEING INTERESTING...WITH ANOTHER SURGE OF WARM AIR PUSHES IN FROM THE SOUTH. AT 00Z WEDNESDAY A WEAK SFC TROUGH MAY STILL BE OVER CENTRAL LAKE SUPERIOR AND NORTHERN UPPER MICHIGAN...BUT THAT FEATURE SHOULD EXIT QUICKLY AS THE LARGE AREA OF HIGH PRESSURE OVER CENTRAL CANADA PUSHES INTO ONTARIO AND LAKE SUPERIOR OVERNIGHT. KEPT CONDITIONS DRY FOR NOW...ALTHOUGH SOME OF THE SMALLER SCALE MODELS DID INDICATE A FEW LIGHT FLURRIES OR SNOW SHOWERS. OTHERWISE...DRY CONDITIONS SHOULD LINGER THROUGH WEDNESDAY MORNING...AS THE HIGH PRESSURE SYSTEM SLOWLY EXITS TO EASTERN ONTARIO AND OVER JAMES BAY BY 00Z THURSDAY. WILL CONTINUE TO HEDGE THE FORECAST CLOSER TO THE ECMWF WITH THIS PACKAGE UPDATE. ALTHOUGH IT IS A LITTLE WEAKER AND EASTWARD WITH THE SURFACE LOW TO OUR SOUTH AND EAST DURING THE DAY THURSDAY...BOTH THE GFS AND ECMWF HAVE THE SURFACE LOW OVER FAR EASTERN UPPER MICHIGAN AT 18Z FRIDAY /ALTHOUGH THE GFS IS DEEPER WITH THE SYSTEM/. PRECIPITATION TYPE AND AMOUNTS REMAIN A CONCERN...WITH RAIN MAINLY CENTRAL AND EAST...CLOSER TO THE LOW. WEDNESDAY NIGHT STILL LOOKS LIKE A POTENTIAL FOR FREEZING RAIN...WITH SURFACE TEMPERATURES OF 29-32F BETWEEN 01-11Z THURSDAY. WHILE THE TYPICAL ROADWAYS MAY STAY WARM ENOUGH FOR WET CONDITIONS DUE TO LINGER SALT DEPOSITS ALREADY ON THEM...AND BEING MORE WELL-TRAVELED. AS WE MOVE DEEPER INTO THE SPRING SEASON IT BECOME INCREASINGLY DIFFICULT FOR ROADWAYS TO STAY BELOW FREEZING FOR TOO LONG. STILL HAVE A GOOD CHANCE OF FREEZING RAIN ACCUMULATING TO GENERALLY LESS THAN A TENTH OF AN INCH. KEPT THE MENTION IN THE HWO AT THIS POINT. ALSO HAVE THE POTENTIAL FOR 2-4 INCHES OF HEAVY WET SNOW OVER THE HIGHER TERRAIN OF THE WEST WEDNESDAY NIGHT...LINGERING INTO THURSDAY WITH A SMALL BREAK FIGURED BEFORE WE COME UNDER THE INFLUENCE OF THE 500MB TROUGH AND COLDER AIR PUSHING IN FOR THURSDAY NIGHT THROUGH FRIDAY NIGHT. NNE 850MB WINDS OF 30-50KT LOOK REALISTIC FROM 06-15Z FRIDAY...BEFORE TURNING MORE NORTHERLY AS THE LOW PUSHES ACROSS EASTERN UPPER MICHIGAN. INTRODUCED GALE FORCE VALUES TO PORTIONS OF MAINLY CENTRAL LAKE SUPERIOR FRIDAY INTO FRIDAY EVENING...BUT WOULD NOT BE SURPRISED IF WE NEED TO BUMP UP OUR FORECAST FOR THE NE WINDS FUNNELING DOWN THE WESTERN HALF OF LAKE SUPERIOR EARLIER IN THE DAY. THE WEST END OF THE CWA /GOGEBIC AND ONTONAGON COUNTIES/ WILL ALSO HAVE THE BEST CHANCE OF LAKE EFFECT/LAKE ENHANCED SNOW ACCUMULATIONS...WITH 850MB TEMPS GENERALLY COOLING BELOW -6C. LIGHTER AMOUNTS ARE FIGURED EAST...WITH WARMER AIR WILL AROUND AND A MIX OF RAIN OR SNOW POSSIBLE FAR EAST THROUGH THE DAY FRIDAY. DRY WEATHER SHOULD BE THE RULE ONCE AGAIN STARTING SATURDAY AS HIGH PRESSURE BUILDS IN AT THE SFC. HOWEVER WITH NW FLOW LINGERING ALOFT AND N-NNW WINDS AT THE SURFACE...ALONG WITH 850MB TEMPS OF -11 TO -14C...LINGERING SNOW SHOWERS WILL BE POSSIBLE EAST OF MARQUETTE NEAR LAKE SUPERIOR INTO THE MID/LATE MORNING HOURS. THERE ARE SIGNIFICANT TIMING DIFFERENCES WITH THE APPROACH OF THE NEXT SYSTEM. THEY DO AGREE ON STRONG S WINDS AT 850MB...AGAIN APPROACHING THE 40-55KT RANGE FROM MAINLY LATE SUNDAY AFTERNOON THROUGH MONDAY MORNING...AS THE LLJ PUSHES W TO E ACROSS THE CWA. THE MAIN ISSUE IS REGARDING THE TIMING OF THE NEXT SURGE OF MOISTURE/PRECIPITATION...WHICH THE 15/12Z GFS IS MUCH MORE PROGRESSIVE AND BRINGS IN MORNING TO THE WEST HALF. THIS IS APPROX 6 OR MORE HOURS FASTER THAN THE 15/06Z GFS RUN. THE 12Z ECMWF SHOWED A SLOWER SOLUTION. GIVEN THE VARIABILITY SHOWN IN THE AVAILABLE MODELS...IT SEEMS REASONABLE TO CONCENTRATE A BIT MORE ON THE NEAR TERM...AND RUN WITH A CONTINUED CONSENSUS APPROACH AFTER 00Z MONDAY. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z TUESDAY NIGHT) ISSUED AT 115 AM EDT TUE APR 16 2013 LOW-LEVEL MOISTURE WRAPPING AROUND MIDLEVEL LOW PASSING JUST N OF LAKE SUPERIOR WILL LIKELY RESULT IN MVFR CIGS AT KIWD/KCMX THRU THE MORNING HRS. APPROACH AND PASSAGE OF SFC TROF LATE IN THE NIGHT SHOULD BRING LOW MVFR CIGS (PERHAPS IFR) TO KCMX ALONG WITH THE POSSIBILITY OF -SHSN/FLURRIES. AT KSAW...VFR CONDITIONS WILL PREVAIL FOR THE NEXT SEVERAL HRS...BUT PASSAGE OF SFC TROF AROUND DAYBREAK SHOULD BRING HIGH MVFR CIGS. MVFR CIGS WILL LIFT/SCATTER OUT MID/LATE AFTN AT KIWD/KCMX. EXPECT CIGS TO RISE TO VFR BY LATE MORNING AT KSAW. VFR CONDITIONS WILL THEN BE THE RULE THRU THE EVENING HRS AT ALL 3 SITES. && .MARINE...(FOR THE 4 PM LAKE SUPERIOR FORECAST ISSUANCE) ISSUED AT 451 PM EDT MON APR 15 2013 SHORT LIVED GALE EVENT WILL CONTINUE TO WIND DOWN EARLY THIS MORNING ACROSS THE EAST HALF OF LAKE SUPERIOR AS THE LOW NEARS THE AREA AND ALSO WEAKENS WHICH WILL WEAKEN THE PRESSURE GRADIENT. WINDS THEN DECREASE TUESDAY INTO WEDNESDAY BEFORE INCREASING OUT OF THE N THURSDAY INTO FRIDAY WHEN GALES MAY BE POSSIBLE AGAIN AS ANOTHER STRONG LATE SPRING SNOWSTORM AFFECTS THE AREA. && .MQT WATCHES/WARNINGS/ADVISORIES... UPPER MICHIGAN... NONE. LAKE SUPERIOR... NONE. LAKE MICHIGAN... NONE. && $$ SHORT TERM...KC LONG TERM...KF AVIATION...ROLFSON MARINE...KC
AREA FORECAST DISCUSSION...UPDATED
NWS ALBUQUERQUE NM
536 PM MDT WED APR 17 2013 .AVIATION... 00Z TAF CYCLE LOW CLOUDS WILL SURGE SOUTH AGAIN TONIGHT AS A POTENT BACK DOOR COLD FRONT SURGES INTO THE EASTERN PLAINS. LATEST RUC AND NAM SOLUTIONS INDICATE LOW CLOUDS NEAR 015 WILL MAKE IT BACK INTO KTCC AND SATELLITE CONFIRMS...SO HAVE ADDED BKN CIGS THERE FOR SEVERAL HOURS TONIGHT. SOME LIGHT PRECIP MAY DEVELOP BEHIND THE FRONT AS WELL HOWEVER LEFT OUT SINCE CONFIDENCE NOT AS HIGH. MODELS BOTH AGREE AS WELL WITH FRONT PUSHING INTO KROW WITH A SCT TO BKN DECK BUT NOT NEARLY AS CONFIDENCE THERE SO LEFT SCT DECK FOR NOW. ELSEWHERE...WINDS AND BLDU WILL TAPER OFF THIS EVENING. PRECIP WILL BECOME TERRAIN DOMINATED OVER THE NORTH WHERE A COUPLE INCHES OF SNOW AND IFR CIGS WILL OCCUR. THE MAIN IMPACT AREA FOR SNOW WILL BE THE NE PLAINS FROM RATON EAST TO CLAYTON. SKIES WILL CLEAR THURSDAY FROM WEST TO EAST...EXCEPT FOR THE NE CORNER WHERE MODELS CONTINUE TO INDICATE SOME LIGHT PRECIP PUSHING EAST OFF THE HIGH TERRAIN. GUYER && .PREV DISCUSSION...330 PM MDT WED APR 17 2013... PLETHORA OF HIGHLIGHTS OUT SO WILL KEEP THIS SHORT. UPPER LEVEL LOW/TROUGH NEAR THE FOUR CORNERS EARLY THIS AFTERNOON. RELATIVELY MOIST SOUTHWEST FLOW ALOFT CONTINUING TO BRING OCCASIONAL LIGHT TO MODERATE SNOW TO PORTIONS OF THE NORTHERN MOUNTAINS. LIGHT ACCUMULATION REPORTED IN CHAMA AND DULCE BY LATE THIS MORNING WITH LIGHT SNOW AND A TRACE OF ACCUMULATION AT ANGEL FIRE. BACKDOOR FRONT REMAINED NEARLY STATIONARY TODAY...FROM NEAR A TRINIDAD TO RATON TO TUCUMCARI LINE. APPROXIMATELY A 40F DIFFERENCE BETWEEN THE AIRMASS TO THE NORTH OF THE FRONT OVER NE NM AND THE AIRMASS OVER SE NM. UPPER LOW/TROUGH WILL CONTINUE TO SLOWLY TRANSLATE EWD THIS EVENING...WITH THE TROUGH AXIS LOCATED ALONG INTERSTATE 25 OR SO BY AROUND MIDNIGHT. NAM AND GFS IN GOOD AGREEMENT THAT AS THE 700MB WAVE CROSSES THE ROCKIES EARLY THIS EVENING...THE MID LEVEL FLOW TURNS NORTHERLY AND THE COLD AIR OVER ERN COLORADO/BACKDOOR FRONT SURGES SOUTHWARD OVERNIGHT. DECIDED TO INCLUDE THE FAR NE HIGHLANDS...UNION AND HARDING COUNTIES IN THE WINTER WEATHER ADVISORY OVERNIGHT. 12Z NAM12 HITTING THIS AREA QUITE HARD WITH SNOW THIS EVENING AND WITH VISIBLE SATELLITE IMAGERY SHOWING SIGNS OF STRONG FRONTOGENETIC FORCING ALONG WITH MID-LEVEL INSTABILITY OVER NE NM/SE CO STARTING TO TAKE SHAPE. UPPER LEVEL TROUGH SLOW TO SHIFT EWD THURSDAY WITH ONE LAST SPEED MAX TO ROUND THE BASE OF THE TROUGH. SURFACE CONVERGENCE ALONG WITH COLD AIR ALOFT WILL LEAD TO SCATTERED SNOW SHOWERS FOR THE NORTHERN MOUNTAINS DURING THE AFTERNOON. DRY NW FLOW ALOFT TRANSITIONS OVERHEAD THURSDAY NIGHT AND FRIDAY. WARMING TREND GETS UNDERWAY AREA-WIDE FRIDAY WITH TEMPERATURES STARTING TO AT LEAST APPROACH AVERAGE LEVELS. THE WARMING TREND CONTINUES INTO THE WEEKEND...ALBEIT A WEAK SHORT-WAVE CLIPS THE FAR NORTH/NE PART OF THE STATE SLOWING THE WARMING TREND THERE WITH A SLIGHT CHANCE FOR A LIGHT MOUNTAIN SHOWER. MEDIUM RANGE GLOBAL MODELS SEEM TO BE SETTLING ON TIMING AND PLACEMENT OF THE NEXT COLD UPPER LEVEL TROUGH AND UNSEASONABLY STRONG BACK DOOR COLD FRONT FOR EARLY NEXT WEEK. 33 .FIRE WEATHER... STRONG SURFACE WINDS AND RELATIVE HUMIDITY BELOW 15 PERCENT WILL CONTINUE TO PRODUCE RED FLAG CONDITIONS THROUGH MID EVENING ACROSS ZONES 106...107 AND 108. STRONGEST WINDS WILL DIMINISH AFTER THAT TIME AND LESSEN THE FIRE WEATHER CONDITIONS. BASE OF UPPER LEVEL LOW WILL MOVE ACROSS NORTHERN NM TONIGHT...WHILE A COLD FRONT PUSHES SOUTHWARD ACROSS EASTERN NM. THESE TWO SYSTEMS WILL PRODUCE LIGHT TO OCCASIONALLY MODERATE SNOWFALL ACROSS THE NORTHERN SANGRE DE CRISTOS...THE NORTHERN HIGHLANDS AND THE FAR NORTHEASTERN PLAINS. WETTING PRECIPITATION IS LIKELY ACROSS THESE AREAS TONIGHT. INCREASING LOW LEVEL MOISTURE TONIGHT WILL PRODUCE VERY GOOD TO EXCELLENT RECOVERIES ACROSS THE NORTHERN MOUNTAINS AND EASTERN PLAINS. FAIR TO GOOD OVERNIGHT RECOVERIES ARE EXPECTED ACROSS THE REMAINDER OF THE REGION. WINDS WILL DROP BELOW 15 MPH ACROSS MOST OF THE REGION AFTER MIDNIGHT...EXCEPT BEHIND THE COLD FRONT IN THE EASTERN PLAINS. A WIND ADVISORY WILL REMAIN IN EFFECT ACROSS THE EASTERN PLAINS THROUGH DAWN THURSDAY WITH NORTH TO NORTHEAST WINDS GREATER THAN 30 MPH. AS THE UPPER LOW MOVES AWAY FROM NM INTO THE U.S. CENTRAL PLAINS THURSDAY...A DEEP NORTHWEST FLOW WILL SET UP ACROSS THE STATE. NORTHWEST WIND WEST OF THE DIVIDE WILL GUST TO 30 MPH IN THE AFTERNOON...BUT RELATIVE HUMIDITY WILL REMAIN ABOVE CRITICAL VALUES. RELATIVE HUMIDITY ACROSS THE SOUTHERN ZONES WILL DIP BRIEFLY BELOW 15 PERCENT...BUT WIND SPEEDS AND GUSTS ACROSS THIS AREA WILL BE LIGHTER. VENTILATION THURSDAY WILL BE VERY GOOD WEST OF THE DIVIDE AND GOOD EAST OF THE DIVIDE. SURFACE HIGH PRESSURE TO THE NORTH WILL BEGIN TO BUILD SOUTHWARD ACROSS NM THURSDAY NIGHT...AND LIGHT NORTH TO NORTHWEST WINDS ARE EXPECTED. EXPECT INVERSIONS TO DEVELOP IN THE VALLEY AND LOW-LYING AREAS LATE THURSDAY NIGHT. RECOVERIES WILL BE FAIR TO GOOD IN MOST LOCATIONS AND WILL BE VERY GOOD TO EXCELLENT ACROSS NORTHERN NM. WEAK HIGH PRESSURE ALOFT AND MODERATE SURFACE HIGH PRESSURE WILL BUILD ACROSS NM FRIDAY. THIS WEATHER PATTERN WILL PRODUCE LIGHT WINDS FOR THE ENTIRE REGION WITH GUSTS GENERALLY LESS THAN 20 MPH IN THE AFTERNOON. MORNING INVERSIONS WILL BE SLOW TO BURN OFF FRIDAY...ESPECIALLY WEST OF THE DIVIDE. SIGNIFICANTLY DRIER AIR WILL MOVE ACROSS NM FROM THE WEST FRIDAY. THIS AIR MASS WILL CAUSE AFTERNOON RELATIVE HUMIDITY TO FALL BELOW 15 PERCENT IN MOST LOCATIONS...EXCEPT IN THE NORTHERN MOUNTAINS. VENTILATION WILL BE POOR TO FAIR DURING THE MORNING HOURS...AND THEN IMPROVE TO GOOD TO VERY GOOD IN THE AFTERNOON. DRY AIR MASS WILL REMAIN IN PLACE ACROSS NM FRIDAY NIGHT. OVERNIGHT RELATIVE HUMIDITY RECOVERIES WILL BE POOR TO FAIR...EXCEPT IN THE NORTHERN MOUNTAINS...WHERE RECOVERIES ARE EXPECTED TO BE GOOD. WINDS WILL BE LIGHT WEST OF THE DIVIDE FRIDAY NIGHT. SURFACE LOW PRESSURE FORMING IN EASTERN CO FRIDAY NIGHT WILL GENERATE LIGHT TO MODERATE SOUTH TO SOUTHEAST WINDS IN THE EASTERN PLAINS. RECOVERIES WILL BE POOR ACROSS SOUTH CENTRAL ZONES AND FAIR ELSEWHERE. A COMBINATION OF DEVELOPING SURFACE LOW PRESSURE ACROSS WESTERN TX AND STRENGTHENING WINDS ALOFT SATURDAY WILL AN INCREASE IN WIND SPEEDS EAST OF THE DIVIDE. AFTERNOON WINDS EAST OF THE DIVIDE WILL GUST UP TO 35 MPH IN THE AFTERNOON HOURS. LOW RELATIVE HUMIDITY AND GUSTY WINDS HAVE THE POTENTIAL TO CREATE 3 TO 5 HOURS OF NEAR CRITICAL FIRE WEATHER CONDITIONS ALONG I-40 FROM CLINES CORNERS TO SANTA ROSA SATURDAY AFTERNOON. VENTILATION WILL BE FAIR TO GOOD IN THE MORNING HOURS AND RAPIDLY IMPROVE IN THE EARLY AFTERNOON TO BECOME EXCELLENT ACROSS ALL OF NM. && .ABQ WATCHES/WARNINGS/ADVISORIES... WINTER WEATHER ADVISORY UNTIL 6 PM MDT THURSDAY FOR THE FOLLOWING ZONES...NMZ515-527-528-530-531. WIND ADVISORY UNTIL 9 PM MDT THIS EVENING FOR THE FOLLOWING ZONES... NMZ521>524-528-529-531>533-536>538. RED FLAG WARNING UNTIL 9 PM MDT THIS EVENING FOR THE FOLLOWING ZONES...NMZ106>108. HARD FREEZE WATCH FROM THURSDAY EVENING THROUGH FRIDAY MORNING FOR THE FOLLOWING ZONES...NMZ519-520-530>538. FREEZE WARNING FROM 2 AM TO 10 AM MDT THURSDAY FOR THE FOLLOWING ZONES...NMZ519-520-534>536. WIND ADVISORY UNTIL 6 AM MDT THURSDAY FOR THE FOLLOWING ZONES... NMZ534-535. HIGH WIND WARNING UNTIL 9 PM MDT THIS EVENING FOR THE FOLLOWING ZONES...NMZ525-526-539-540. WINTER WEATHER ADVISORY UNTIL 6 PM MDT THURSDAY FOR THE FOLLOWING ZONES...NMZ510-512>514. && $$
AREA FORECAST DISCUSSION
NWS BURLINGTON VT
654 PM EDT TUE APR 16 2013 .SYNOPSIS... A COLD FRONT WILL MOVE ACROSS THE REGION THIS EVENING ACCOMPANIED BY RAIN SHOWERS. A RIDGE OF HIGH PRESSURE WILL BUILD SOUTH INTO THE REGION FROM CANADA ON WEDNESDAY. A WARM FRONT WILL APPROACH THE REGION ON THURSDAY. IT WILL WARM AND WINDY FRIDAY FOLLOWED BY SHOWERS FRIDAY NIGHT AS ANOTHER COLD FRONT MOVES ACROSS THE NORTH COUNTRY. && .NEAR TERM /UNTIL 6 AM WEDNESDAY MORNING/... AS OF 654 PM EDT TUESDAY...PRE-FRONTAL RAIN SHOWERS HAVE EXITED THE NORTH COUNTRY...THOUGH RECENT COMPOSITE RADAR SHOWS A FAIRLY SOLID LINE OF RAIN SHOWERS APPROACHING THE SAINT LAWRENCE VALLEY AND NORTHERN ADIRONDACKS OF NEW YORK. THESE SHOWERS ARE TIED TO THE COLD FRONT AND HAVE GONE WITH AREAL COVERAGE WORDING TO HANDLE THESE SHOWERS AS THEY MOVE ACROSS THE NORTH COUNTRY. RAP ANALYSES SHOW A 85-95KT MID-LEVEL JET STREAK ORIENTED NORMAL TO THE SFC BOUNDARY WHICH SUGGESTS THAT THE FRONT WILL BE QUICK TO MOVE EAST. EXPECT THAT THESE SHOWERS WILL CONTINUE TO PROGRESS STEADILY EASTWARD...CLEARING THE NORTH COUNTRY AROUND 05Z OR SO. THERE COULD BE SOME BRIEF DOWNPOURS WITH THESE SHOWERS AS THEY MOVE EAST...THOUGH QPF AMOUNTS SHOULD BE ON THE LIGHT SIDE. BEST INSTABILITY REMAINS WELL SOUTH SO NOT EXPECTING ANY THUNDER WITH THIS ACTIVITY. A SHARP WIND SHIFT TO WEST/WEST-NORTHWEST IS EXPECTED WITH CLEARING SKIES AND A NOTICEABLY DRIER AIRMASS FILTERING INTO THE REGION. UNTIL THAT TIME...HAVE RAISED DEWPOINTS UP SEVERAL DEGREES WITH DRYING OCCURRING WITH THE FRONT THEREAFTER. HAVE LEFT TEMPERATURES LARGELY UNCHANGED AND WILL EVALUATE AS THE EVENING PROGRESSES. && .SHORT TERM /6 AM WEDNESDAY MORNING THROUGH THURSDAY NIGHT/... AS OF 357 PM EDT TUESDAY...HIGH PRESSURE WILL BUILD INTO THE REGION ON WEDNESDAY. CENTER OF THE HIGH REMAINS OVER THE JAMES BAY REGION WITH SEASONABLY COOL NORTHERLY FLOW EXPECTED ACROSS THE NORTH COUNTRY. THUS...TEMPERATURES WILL BE A LITTLE LOWER THAN ON TUESDAY WITH HIGHS IN THE 50S. DRY WEATHER CONTINUES WEDNESDAY NIGHT ALTHOUGH THERE WILL BE AN INCREASE IN CLOUDS WITH ONSET OF WARM AIR ADVECTION AS HIGH PRESSURE MOVES FURTHER EAST AND RETURN SOUTHERLY FLOW DEVELOPS BY THURSDAY MORNING. A WARM FRONT WILL APPROACH THE REGION ON THURSDAY. HAVE GONE WITH CHANCE POPS FOR A FEW SHOWERS...MAINLY OVER NORTHERN ZONES. DESPITE CLOUD COVER...INCREASING SOUTHERLY FLOW WILL ALLOW FOR MILDER TEMPS...WITH HIGHS WELL INTO THE 50S TO LOWER 60S. FURTHER INCREASE IN SOUTHERLY FLOW THURSDAY NIGHT...SO EXPECT A MILD NIGHT AND MAINLY DRY AS FORECAST AREA WILL BE IN WARM SECTOR. && .LONG TERM /FRIDAY THROUGH TUESDAY/... AS OF 355 PM EDT TUESDAY...CONSISTENT FORECAST CONTINUES WITH WARM MAX TEMPERATURES ON FRIDAY AS 850MB TEMPS INCREASE TO ABOUT 10C-12C. SOUTHERLY FLOW...WAA AND SOME BREAKS IN CLOUDS WILL WARM SFC TEMPS INTO THE 60S AND L70S. A COLD FRONT WILL APPROACH FROM THE WEST ON THE LATTER HALF OF FRIDAY INTO FRIDAY NIGHT. THIS FRONT COULD TRIGGER SOME ISOLATED TS...BUT PARAMETERS NOT QUITE LINING UP TIME-WISE. TEMP LAPSE RATES OF 6+C/KM LOWERING AS AREA OF CAPE MOVES EASTWARD INTO NRN NY. ALSO LIFTED INDICES STAYING ABOVE ZERO...SO HAVE NOT INCLUDED TS IN FCST AT THIS TIME. WITH THIS SYSTEM...GEFS SHOWING PWATS VALUES OF 2-3 STANDARD DEVIATIONS ABOVE NORMAL OVER THE NORTH COUNTRY...WITH QPF AMOUNTS UP TO A HALF INCH THROUGH SATURDAY. PRECIP AND COLD FRONT SHOULD EXIT ERN VT SOMETIME ON SATURDAY...FOLLOWED BY HIGH PRESSURE BUILDING INTO THE GREAT LAKES REGION. THIS RIDGE OF HIGH PRESSURE WILL CREST OVER THE REGION SUNDAY NIGHT AND SLIDE EAST OVER NOVA SCOTIA ON MONDAY. DRY CONDITIONS WILL LINGER INTO THE BEGINNING OF NEXT WEEK. TEMPERATURES STARTING WARM WITH WAA AND SOUTHERLY FLOW AHEAD OF THE COLD FRONT. A GENERAL COOLING TREND OVER THE WEEKEND BEHIND THE FRONT. FRIDAY NT MIN TEMPS WILL BE IN THE 40S. SATURDAY AND SUNDAY MAX TEMPS WILL BE IN THE 40S TO L50S. SATURDAY NT AND SUNDAY NT EXPECT BELOW NORMAL MIN TEMPS IN THE L20S-L30S. TEMPS WILL WARM SLIGHTLY AS THE HIGH PRESSURE CRESTS OVER THE REGION AND WE GET A RETURN TO SOUTHERLY FLOW. MONDAY MAX TEMPS WILL REACH THE M40S-U50S AND MIN TEMPS MONDAY NIGHT WILL BE IN THE M20S-M30S. && .AVIATION /00Z WEDNESDAY THROUGH SUNDAY/... THROUGH 18Z WEDNESDAY...GUSTY SOUTHERLY WINDS WILL CONTINUE INTO THIS EVENING AS LLJ REMAINS OVER THE NORTH COUNTRY. PRECIP HAS MOVED OVER KMSS AND KSLK WITH MVFR CIGS AT KSLK. SO MAINLY VFR CONDITIONS WILL SEE MVFR CIGS AND OCCASIONAL MVFR VSBYS IN RAIN SHOWERS THIS AFTERNOON AND EARLY EVENING AS A COLD FRONT MOVES EASTWARD THROUGH THE AREA. RAIN WILL GENERALLY BE LIGHT. BEHIND THE FRONT...WINDS WILL SHIFT MORE WESTERLY AND WIND GUSTS WILL TAPER DOWN TO 15-25 KTS. OVERNIGHT...MAINLY AFTER 06Z...SKIES WILL BEGIN TO CLEAR OUT AND GUSTS WILL FADE...LEAVING NW WINDS AT 5-10 KTS. APPROACHING WEDNESDAY MORNING...WINDS WILL PICK UP AT 8-12KTS OUT OF THE NW WITH MAINLY CLEAR SKIES. OUTLOOK 18Z WEDNESDAY THROUGH SUNDAY... 18Z WEDNESDAY THROUGH 12Z THURSDAY...VFR CONDITIONS EXPECTED AS A RIDGE OF HIGH PRESSURE WILL BE OVER THE REGION. 12Z THURSDAY THROUGH 00Z FRIDAY...VFR/AREAS OF MVFR POSSIBLE AS A WARM FRONT WILL BRING A CHANCE OF RAIN SHOWERS TO NY. VFR EXPECTED OVER VT. 00Z FRIDAY THROUGH 00Z SATURDAY...MAINLY VFR CONDITIONS EXPECTED. 00Z SATURDAY THROUGH 00Z SUNDAY...VFR/MVFR CONDITIONS AS COLD FRONT BRINGS RAIN ACROSS THE NORTH COUNTRY. 00Z SUNDAY ONWARD...VFR CONDITIONS AS HIGH PRESSURE BUILDS INTO THE REGION. && .BTV WATCHES/WARNINGS/ADVISORIES... VT...NONE. NY...NONE. && $$ SYNOPSIS...RJS NEAR TERM...RJS/LOCONTO SHORT TERM...RJS LONG TERM...KGM AVIATION...KGM
AREA FORECAST DISCUSSION
NWS BINGHAMTON NY
144 PM EDT TUE APR 16 2013 .SYNOPSIS... SOUTHERLY WIND WILL CONTINUE TO BRING CLOUDS AND THEN INCREASING CHANCES OF SHOWERS FROM THE WEST LATER THIS MORNING. A COLD FRONT WILL MOVE ACROSS CENTRAL NEW YORK THIS AFTERNOON...AND INTO NORTHEAST PENNSYLVANIA THIS EVENING WITH SHOWERS AND A SLIGHT CHANCE OF THUNDERSTORMS. ANY STORMS THAT FORM MAY CONTAIN GUSTY WINDS. SHOWERS WILL END OVERNIGHT...LEAVING WEDNESDAY DRY. WARMER AIR WILL RETURN TO THE REGION FOR THURSDAY...FOLLOWED BY A STRONG COLD FRONT FRIDAY. && .NEAR TERM /THROUGH TONIGHT/... 115 PM UPDATE... FIRST BATCH OF RAIN CURRENTLY MOVING THROUGH THE REGION WHICH APPEARS TO ASSOCIATED WITH A WEAK SHORTWAVE MOVING OVERHEAD. LIGHTNING ACTIVITY WITH THIS FIRST CLUSTER HAS DECREASED MARKEDLY WITH PROGRESSION THROUGH THE CWA SIGNIFYING THE CURRENT STABILITY OF THE ATMOSPHERE. ATTENTION NOW FOCUSED ON UPSTREAM LOCATIONS ACROSS THE WESTERN FINGER LAKES AND WESTERN SOUTHERN TIER WHERE RECENT VIS SATELLITE TRENDS HAVE SHOWN SOME PARTIAL BREAKS IN THE OVERLYING CLOUD COVER. LATEST RUC MLCAPE FIELDS SHOWING LATTERLY NO INSTABILITY ACROSS UPSTATE NY THIS HR BUT HIGH-RES MODELS DO SUGGEST A WEAK LINE FORMING ALONG THE FRONT AS IT PUSHES THROUGH LATER THIS AFTERNOON. AS SUCH...WILL CONTINUE TO ADVERTISE A SLGT CHC THUNDER MENTION THIS AFTERNOON/EARLY EVENING BEFORE HIGH PRESSURE BUILDING SOUTH FROM SOUTHERN CANADA LEADS TO DRIER AIR AND A NORTH TO SOUTH REDUCTION IN PRECIP DURING THE EVENING HRS. MAX TEMPS ADJUSTED SLIGHTLY BASED ON CURRENT RAIN ACTIVITY MOVING THROUGH THE AREA BUT LOW TO MID 60S STILL LOOK REASONABLE. NO OTHER CHANGES NEEDED AT THE PRESENT TIME. 10 AM UPDATE... MAIN CONCERN HEADING INTO THE AFTERNOON CONTINUES TO BE CONVECTIVE DEVELOPMENT AND A LIMITED SEVERE POTENTIAL AS KINEMATIC FIELDS REMAIN MORE THAN SUPPORTIVE FOR SEVERE WX SUSTAINMENT. THAT SAID...MAIN LIMITING FACTOR CONTINUES TO BE EXTENSIVE CLOUD COVER WHICH IS VIEWABLE ON LATEST VIS SATELLITE PICS THIS MORNING WHICH WILL UNDOUBTEDLY PREVENT MAX TEMPS FROM WARMING TO THEIR MAX POTENTIAL THIS AFTERNOON. LATEST REGIONAL RADAR TRENDS NOW SHOWING AN AREA OF SHWRS/EMBEDDED THUNDER APPROACHING THE WESTERN SOUTHERN TIER AND 1-HR GRIDS HAVE BEEN UPDATED TO REFLECT CURRENT ACTIVITY. WITH ANY CLEARING DISPLACED WELL TO OUR SOUTHWEST NEAR PITTSBURGH...ITS HARD AT THIS POINT TO SURMISE THAT REGION WILL SEE ANY APPRECIABLE CLEARING/DESTABILIZATION PRIOR TO FROPA LATER THIS AFTERNOON. THAT BEING SAID...WILL LEAVE A SLGT CHC THUNDER MENTION THROUGH THIS AFTERNOON AS FRONT SLOWLY MOVES THROUGH THE FCST AREA. CURRENT THINKING IS APPROACHING PREFERENTIAL ACTIVITY ACROSS THE WESTERN SOUTHERN TIER WILL LIKELY STABILIZE THE LOW- LEVEL ENVIRONMENT EVEN FURTHER WHICH WILL LIKELY KEEP ANY SEVERE WX DEVELOPMENT IN CHECK. WILL HAVE TO WATCH MOISTURE POOLING (LOW 50 DEW POINTS) ALONG THE BOUNDARY AS IT MOVES THROUGH BUT WITH MAX MID/UPPER-LEVEL FORCING REMAIN DISPLACED WELL TO THE NORTH...OVERALL SEVERE WX THREAT LOOKS VERY MARGINAL AT THIS TIME. 7 AM UPDATE... FORECAST DETAILS TWEAKED WHERE NEEDED...EXPECTATIONS AND CONCERNS FOR FRONT THIS AFTERNOON/EVENING REMAIN THE SAME AS DISCUSSED BELOW. PREVIOUS DISCUSSION... WE HAVE HAD A MILD NIGHT WITH SOUTHEAST TO SOUTH FLOW. MANY LOCATIONS NOT ALREADY IN THE 50S WILL BE WITHIN THE NEXT FEW HOURS...THOUGH CATSKILLS/POCONOS EASTWARD WILL HOLD ON TO 40S THE LONGEST DUE TO MARINE-INFLUENCED LAYER. WATER VAPOR IMAGERY SHOWS STORMS THAT BLEW UP ACROSS MISSOURI/ILLINOIS AND HEADING INTO INDIANA...ASSOCIATED WITH A SHORTWAVE THAT WILL BE A PLAYER IN OUR WEATHER LATER TODAY. FOR NOW...STILL DRY. MODELS EARLIER STRUGGLED WITH THE LEAD SHORTWAVE...BUT LATEST RUNS HAVE CAUGHT ON TO IT AND AS PER VORTICITY FIELDS BRING THE WAVE THROUGH OUR REGION 15Z-19Z. AT THIS TIME I FEEL THERE WILL BE A FAIR BATCH OF SHOWERS MOVING IN ASSOCIATED WITH THAT WAVE...ESPECIALLY CENTRAL TO NORTHWEST ZONES...WHICH WILL RUN WELL AHEAD OF THE SURFACE FRONT. THE CLOUDS FROM THIS WAVE WILL PROBABLY FURTHER INHIBIT THE ALREADY LIMITED INSTABILITY FOR CONVECTION THIS AFTERNOON/EVENING. ALSO...THE CLOUD COVER WILL ALSO HELP TO KEEP THE STRONG LOW LEVEL JET...40-55 KTS AT 850MB...FROM EFFECTIVELY MIXING DOWN TO THE SURFACE. THAT BEING SAID...STILL EXPECT A PRETTY GOOD BREEZE TODAY...INCLUDING GUSTS REACHING 20-30 MPH IN NEPA /ESPECIALLY HIGHER ELEVS/ AND 25-35 MPH IN CENTRAL NY. LAKE PLAIN AND SYRACUSE IN PARTICULAR COULD HAVE SOME FAIRLY STRONG DOWNSLOPING GUSTS...PERHAPS ONE OR TWO AROUND 40 MPH BUT NOT FREQUENTLY BEYOND THAT SO NO WIND ADVISORY SEEMS WARRANTED. MODELS ARE WELL CONVERGED ON TIMING OF SURFACE FRONT...AGAIN JUST SLIGHTLY DELAYED FROM PRIOR MODEL RUNS...FROM CORNING-SYRACUSE AREA 21Z...TO TOWANDA-BINGHAMTON-ONEONTA 00Z...AND THEN EXITING SOUTHEAST OF MONTICELLO-SCRANTON BY AROUND 03Z OR SO. INSTABILITY WILL ONLY BE MARGINAL...AN AXIS RANGING FROM VERY LITTLE TO A FEW HUNDRED J/KG OR SO IN THE MODELS. I HAVE FOCUSED OUR SLIGHT TO LOW CHANCE OF THUNDER TO DIRECTLY WITH THE FRONT ITSELF WHERE THERE IS GREAT LOW LEVEL CONVERGENCE. THE LEAD SHORTWAVE MAY INTERFERE WITH HEATING...PROBABLY AT LEAST SOMEWHAT INHIBITING INSTABILITY FROM BEING FULLY REALIZED. WE ARE CURRENTLY NOT PEGGED FOR SLIGHT RISK OF SEVERE BY THE STORM PREDICTION CENTER...IN FACT NOT EVEN IN THE GENERAL THUNDER OUTLOOK AS OF 430 AM...BUT THINGS WILL NEED TO BE MONITORED CLOSELY BECAUSE SHOULD CONVECTION GET WELL ORGANIZED ALONG THE FRONT...A GOOD AMOUNT OF SHEAR COULD LEAD TO STRONG GUSTS. 0-1 KM SHEAR ALONG FRONT IN THE NAM IS 30-40 KTS. SHOWERS WILL DIMINISH FAIRLY QUICKLY BEHIND THE FRONT OVERNIGHT. DESPITE PRECIPITABLE WATER VALUES GETTING A BIT PAST 1.25 INCHES ALONG THE FRONT...THINGS WILL MOVE THROUGH QUICKLY ENOUGH CONSIDERING THE FLOW ALOFT AND PACE OF FRONT...TO LIMIT AREAL AVERAGE RAIN AMOUNTS TO A FEW TENTHS OF AN INCH IN NEPA AND BETWEEN QUARTER AND HALF INCH IN CENTRAL NY TODAY THROUGH TONIGHT. && .SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/... 445 AM UPDATE... HIGH PRESSURE TEMPORARILY TAKES CHARGE WEDNESDAY...WITH SHALLOW POOL OF COOLER STABLE POST-FRONTAL AIR. A DECENT DAY WITH HIGH TEMPERATURES STILL NEAR CLIMATOLOGY IF NOT EVEN A TOUCH ABOVE. FRONTAL ZONE WILL BE SITUATED TO OUR SOUTH...BUT CLOSE ENOUGH FOR MID TO HIGH LEVEL CLOUDS TO HANG AROUND FOR THE SOUTHERN ZONES. TOWARDS LAKE PLAIN AND MOHAWK VALLEY...PLENTY OF SUN. FRONTAL ZONE LIFTS BACK NORTHWARD WEDNESDAY NIGHT...WITH CLOUDS BUT ONLY SLIGHT TO LOW CHANCES OF LIGHT SHOWERS DUE TO UPPER RIDGING AND THUS LACK OF LIFT. THIS OPENS THE DOOR TO WARM RETURN FLOW AGAIN THURSDAY...WITH EXPECTED HIGHS IN THE 60S TO LOW 70S /WARMEST FOR LAKE PLAIN TO SYRACUSE COURTESY OF DOWNSLOPING/. 1000-500MB THICKNESSES SURGE INTO THE 560S DECAMETER RANGE. THURSDAY LOOKS MAINLY DRY...BUT WITH A CAVEAT. WITH UPPER RIDGE AXIS ALREADY SHIFTING EAST THURSDAY...WE GET ON EDGE OF QUICK SOUTHWESTERLY FLOW WHICH MAY BE RIDDLED WITH LITTLE SHORTWAVES. ODDLY ENOUGH...THE 00Z NAM EVEN SUGGESTS ONE OF THOSE WAVES IMPACTING THE CENTRAL SOUTHERN TIER THURSDAY EVENING WITH SHOWERS COUPLED WITH INSTABILITY. 06Z NAM THOUGH IS BACKING OFF THIS IDEA...WHILE OTHER MODELS KEEP INSTABILITY MUCH FARTHER WEST DUE TO FAIRLY STABLE LOW LEVELS FROM EARLIER MARINE-INFLUENCED LAYER ADVECTING IN WEDNESDAY NIGHT/THURSDAY. MAINLY 50S FOR LOWS THURSDAY NIGHT...WITH ONLY SLIGHT CHANCE POPS AT BEST...AS WE AWAIT NEXT PROGRESSIVE COLD FRONT WHICH WILL STILL BE WELL TO THE WEST /BUT INBOUND FOR FRIDAY/. && .LONG TERM /FRIDAY THROUGH MONDAY/... 3 PM MON UPDATE... ONLY MINIMAL CHGS MADE TO THE GRIDS ATTM...AS THE LARGE-SCALE PATN IN THE MODELS REMAINS SIMILAR. THE MAIN FEATURE TO WATCH EARLY IN THE PD IS A FAIRLY STG AND PROGRESSIVE COLD FRNT...SLATED TO COME THROUGH NY/PA BY FRI EVE. WE`LL CONTINUE TO ADVERTISE LIKELY POPS THIS PD FOR SHWRS. CONVECTIVE EVOLUTION REMAINS UNCERTAIN...OWING TO THE DEGREE OF DESTABILIZATION AHD OF THE FRNT. FOR NOW...WE`VE THROWN IN A CHC OF TSTMS...TO GO ALG WITH THE LIKELIHOOD OF SHWRS. AFTERWARDS...DRIER AIR WILL GRADUALLY FILTER IN...AS A SFC HIGH BUILDS OUT OF S-CNTRL CANADA. A FEW -SHRA/SPRINKLES COULD LINGER FRI NGT...PERHAPS EVEN INTO EARLY SAT...UNDERNEATH THE SRN END OF AN UPR-LVL TROUGH. OTHWS...THOUGH...THE WEEKEND INTO EARLY NEXT WEEK LOOKS DRY AND COOL...FROM THIS EARLY VANTAGE PT. PREV DISC... THE PERIOD BEGINS WITH A JET DIGGING A SHARP TROF INTO THE SOUTHERN PLAINS, BRINGING MUCH BELOW AVERAGE TEMPS TO THE CENTRAL U.S. AN EASTERN RIDGE DEVELOPS IN RESPONSE, WITH AN ACTIVE WEATHER PATTERN DEVELOPING IN THE SOUTHWESTERLY FLOW UP THE BACK SIDE OF THE RIDGE FROM IL/MO TO THE LOWER GREAT LAKES. STORMS RIDING UP THROUGH THE GREAT LAKES WILL HELP PULL WARM/MOIST AIR INTO NY/PA. THIS WILL LEAD TO A SHOWERY, MILD PATTERN AT THE ONSET OF THE LONG TERM PERIOD. A GREAT LAKES CYCLONE INTENSIFIES OVER NORTHERN MICHIGAN ON FRIDAY, WHILE AN ATLANTIC ANTICYCLONE BUILDS. PRESSURE GRADIENT STRENGTHENS AS A RESULT THROUGH NY/PA. PRECIPITATION TIMING AND CLOUD COVER WILL HAVE A LOT TO SAY ABOUT MAX TEMPS COME FRIDAY. 925MB TEMPS OF 15-17C ARE PROGGED BY ECMWF TO EXTEND THROUGH UPSTATE NY BY 18Z. CLOUDS ARE LIKELY TO SUPPRESS MAXES, BUT ANY BREAKS WILL ALLOW TEMPS TO PUSH THROUGH THE 70S AND ENHANCE INSTABILITY AHEAD OF COLD FRONT. UNTIL INSTABILITY CAN BE BETTER PROGGED, WILL STICK TO FORECAST FOR SHOWERS AND JUST A CHANCE OF THUNDER. COOLER/DRIER AIR FOLLOWS THE COLD FRONT FOR THE WEEKEND. && .AVIATION /18Z TUESDAY THROUGH SUNDAY/... 18Z TUE UPDATE... MVFR RESTRICTIONS ARE EXPECTED MUCH OF THE TIME THIS AFTN (LWR CIGS/SCTD -SHRA). A NARROW LINE/BAND OF SHRA IS EXPECTED TO ACCOMPANY A FROPA EARLY THIS EVE (23Z-03Z)...WITH SOME IFR PSBL AT KBGM/KITH...WHILE MVFR SHOULD CONTINUE TO BE THE PREDOMINANT CONDITION ELSEWHERE. BEHIND THE FRNT...LWR CLDS WILL PERSIST FOR A TIME (AGN IFR PROBABLE ON THE HILLTOPS AT KBGM/KITH...WITH MVFR ELSEWHERE). LTR TNT...DRIER AIR WILL PUSH DOWN FROM THE NW...WITH AT LEAST PTL CLEARING ANTICIPATED...AND A RETURN TO VFR AREA-WIDE. VFR SHOULD THEN CONTINUE THROUGH 18Z WED. GUSTY SRLY WINDS THROUGH EARLY EVE (UP TO 20-25 KT)...WILL SHIFT INTO THE NW AND N OVERNIGHT AND WED. .OUTLOOK... WED NGT THROUGH SUN...MOSTLY VFR. LWR CIGS PSBL THU/FRI AM...AND RESTRICTIONS PSBL FROM SHRA/TSRA FRI AFTN/EVE. && .BGM WATCHES/WARNINGS/ADVISORIES... PA...NONE. NY...NONE. && $$ SYNOPSIS...MDP NEAR TERM...CMG/MDP SHORT TERM...MDP LONG TERM...DJP/MLJ AVIATION...MLJ/MSE
AREA FORECAST DISCUSSION
NWS BINGHAMTON NY
130 PM EDT TUE APR 16 2013 .SYNOPSIS... SOUTHERLY WIND WILL CONTINUE TO BRING CLOUDS AND THEN INCREASING CHANCES OF SHOWERS FROM THE WEST LATER THIS MORNING. A COLD FRONT WILL MOVE ACROSS CENTRAL NEW YORK THIS AFTERNOON...AND INTO NORTHEAST PENNSYLVANIA THIS EVENING WITH SHOWERS AND A SLIGHT CHANCE OF THUNDERSTORMS. ANY STORMS THAT FORM MAY CONTAIN GUSTY WINDS. SHOWERS WILL END OVERNIGHT...LEAVING WEDNESDAY DRY. WARMER AIR WILL RETURN TO THE REGION FOR THURSDAY...FOLLOWED BY A STRONG COLD FRONT FRIDAY. && .NEAR TERM /THROUGH TONIGHT/... 115 PM UPDATE... FIRST BATCH OF RAIN CURRENTLY MOVING THROUGH THE REGION WHICH APPEARS TO ASSOCIATED WITH A WEAK SHORTWAVE MOVING OVERHEAD. LIGHTNING ACTIVITY WITH THIS FIRST CLUSTER HAS DECREASED MARKEDLY WITH PROGRESSION THROUGH THE CWA SIGNIFYING THE CURRENT STABILITY OF THE ATMOSPHERE. ATTENTION NOW FOCUSED ON UPSTREAM LOCATIONS ACROSS THE WESTERN FINGER LAKES AND WESTERN SOUTHERN TIER WHERE RECENT VIS SATELLITE TRENDS HAVE SHOWN SOME PARTIAL BREAKS IN THE OVERLYING CLOUD COVER. LATEST RUC MLCAPE FIELDS SHOWING LATTERLY NO INSTABILITY ACROSS UPSTATE NY THIS HR BUT HIGH-RES MODELS DO SUGGEST A WEAK LINE FORMING ALONG THE FRONT AS IT PUSHES THROUGH LATER THIS AFTERNOON. AS SUCH...WILL CONTINUE TO ADVERTISE A SLGT CHC THUNDER MENTION THIS AFTERNOON/EARLY EVENING BEFORE HIGH PRESSURE BUILDING SOUTH FROM SOUTHERN CANADA LEADS TO DRIER AIR AND A NORTH TO SOUTH REDUCTION IN PRECIP DURING THE EVENING HRS. MAX TEMPS ADJUSTED SLIGHTLY BASED ON CURRENT RAIN ACTIVITY MOVING THROUGH THE AREA BUT LOW TO MID 60S STILL LOOK REASONABLE. NO OTHER CHANGES NEEDED AT THE PRESENT TIME. 10 AM UPDATE... MAIN CONCERN HEADING INTO THE AFTERNOON CONTINUES TO BE CONVECTIVE DEVELOPMENT AND A LIMITED SEVERE POTENTIAL AS KINEMATIC FIELDS REMAIN MORE THAN SUPPORTIVE FOR SEVERE WX SUSTAINMENT. THAT SAID...MAIN LIMITING FACTOR CONTINUES TO BE EXTENSIVE CLOUD COVER WHICH IS VIEWABLE ON LATEST VIS SATELLITE PICS THIS MORNING WHICH WILL UNDOUBTEDLY PREVENT MAX TEMPS FROM WARMING TO THEIR MAX POTENTIAL THIS AFTERNOON. LATEST REGIONAL RADAR TRENDS NOW SHOWING AN AREA OF SHWRS/EMBEDDED THUNDER APPROACHING THE WESTERN SOUTHERN TIER AND 1-HR GRIDS HAVE BEEN UPDATED TO REFLECT CURRENT ACTIVITY. WITH ANY CLEARING DISPLACED WELL TO OUR SOUTHWEST NEAR PITTSBURGH...ITS HARD AT THIS POINT TO SURMISE THAT REGION WILL SEE ANY APPRECIABLE CLEARING/DESTABILIZATION PRIOR TO FROPA LATER THIS AFTERNOON. THAT BEING SAID...WILL LEAVE A SLGT CHC THUNDER MENTION THROUGH THIS AFTERNOON AS FRONT SLOWLY MOVES THROUGH THE FCST AREA. CURRENT THINKING IS APPROACHING PREFERENTIAL ACTIVITY ACROSS THE WESTERN SOUTHERN TIER WILL LIKELY STABILIZE THE LOW- LEVEL ENVIRONMENT EVEN FURTHER WHICH WILL LIKELY KEEP ANY SEVERE WX DEVELOPMENT IN CHECK. WILL HAVE TO WATCH MOISTURE POOLING (LOW 50 DEWPOINTS) ALONG THE BOUNDARY AS IT MOVES THROUGH BUT WITH MAX MID/UPPER-LEVEL FORCING REMAIN DISPLACED WELL TO THE NORTH...OVERALL SEVERE WX THREAT LOOKS VERY MARGINAL AT THIS TIME. 7 AM UPDATE... FORECAST DETAILS TWEAKED WHERE NEEDED...EXPECTATIONS AND CONCERNS FOR FRONT THIS AFTERNOON/EVENING REMAIN THE SAME AS DISCUSSED BELOW. PREVIOUS DISCUSSION... WE HAVE HAD A MILD NIGHT WITH SOUTHEAST TO SOUTH FLOW. MANY LOCATIONS NOT ALREADY IN THE 50S WILL BE WITHIN THE NEXT FEW HOURS...THOUGH CATSKILLS/POCONOS EASTWARD WILL HOLD ON TO 40S THE LONGEST DUE TO MARINE-INFLUENCED LAYER. WATER VAPOR IMAGERY SHOWS STORMS THAT BLEW UP ACROSS MISSOURI/ILLINOIS AND HEADING INTO INDIANA...ASSOCIATED WITH A SHORTWAVE THAT WILL BE A PLAYER IN OUR WEATHER LATER TODAY. FOR NOW...STILL DRY. MODELS EARLIER STRUGGLED WITH THE LEAD SHORTWAVE...BUT LATEST RUNS HAVE CAUGHT ON TO IT AND AS PER VORTICITY FIELDS BRING THE WAVE THROUGH OUR REGION 15Z-19Z. AT THIS TIME I FEEL THERE WILL BE A FAIR BATCH OF SHOWERS MOVING IN ASSOCIATED WITH THAT WAVE...ESPECIALLY CENTRAL TO NORTHWEST ZONES...WHICH WILL RUN WELL AHEAD OF THE SURFACE FRONT. THE CLOUDS FROM THIS WAVE WILL PROBABLY FURTHER INHIBIT THE ALREADY LIMITED INSTABILITY FOR CONVECTION THIS AFTERNOON/EVENING. ALSO...THE CLOUD COVER WILL ALSO HELP TO KEEP THE STRONG LOW LEVEL JET...40-55 KTS AT 850MB...FROM EFFECTIVELY MIXING DOWN TO THE SURFACE. THAT BEING SAID...STILL EXPECT A PRETTY GOOD BREEZE TODAY...INCLUDING GUSTS REACHING 20-30 MPH IN NEPA /ESPECIALLY HIGHER ELEVS/ AND 25-35 MPH IN CENTRAL NY. LAKE PLAIN AND SYRACUSE IN PARTICULAR COULD HAVE SOME FAIRLY STRONG DOWNSLOPING GUSTS...PERHAPS ONE OR TWO AROUND 40 MPH BUT NOT FREQUENTLY BEYOND THAT SO NO WIND ADVISORY SEEMS WARRANTED. MODELS ARE WELL CONVERGED ON TIMING OF SURFACE FRONT...AGAIN JUST SLIGHTLY DELAYED FROM PRIOR MODEL RUNS...FROM CORNING-SYRACUSE AREA 21Z...TO TOWANDA-BINGHAMTON-ONEONTA 00Z...AND THEN EXITING SOUTHEAST OF MONTICELLO-SCRANTON BY AROUND 03Z OR SO. INSTABILITY WILL ONLY BE MARGINAL...AN AXIS RANGING FROM VERY LITTLE TO A FEW HUNDRED J/KG OR SO IN THE MODELS. I HAVE FOCUSED OUR SLIGHT TO LOW CHANCE OF THUNDER TO DIRECTLY WITH THE FRONT ITSELF WHERE THERE IS GREAT LOW LEVEL CONVERGENCE. THE LEAD SHORTWAVE MAY INTERFERE WITH HEATING...PROBABLY AT LEAST SOMEWHAT INHIBITING INSTABILITY FROM BEING FULLY REALIZED. WE ARE CURRENTLY NOT PEGGED FOR SLIGHT RISK OF SEVERE BY THE STORM PREDICTION CENTER...IN FACT NOT EVEN IN THE GENERAL THUNDER OUTLOOK AS OF 430 AM...BUT THINGS WILL NEED TO BE MONITORED CLOSELY BECAUSE SHOULD CONVECTION GET WELL ORGANIZED ALONG THE FRONT...A GOOD AMOUNT OF SHEAR COULD LEAD TO STRONG GUSTS. 0-1 KM SHEAR ALONG FRONT IN THE NAM IS 30-40 KTS. SHOWERS WILL DIMINISH FAIRLY QUICKLY BEHIND THE FRONT OVERNIGHT. DESPITE PRECIPITABLE WATER VALUES GETTING A BIT PAST 1.25 INCHES ALONG THE FRONT...THINGS WILL MOVE THROUGH QUICKLY ENOUGH CONSIDERING THE FLOW ALOFT AND PACE OF FRONT...TO LIMIT AREAL AVERAGE RAIN AMOUNTS TO A FEW TENTHS OF AN INCH IN NEPA AND BETWEEN QUARTER AND HALF INCH IN CENTRAL NY TODAY THROUGH TONIGHT. && .SHORT TERM /WEDNESDAY THROUGH THURSDAY NIGHT/... 445 AM UPDATE... HIGH PRESSURE TEMPORARILY TAKES CHARGE WEDNESDAY...WITH SHALLOW POOL OF COOLER STABLE POST-FRONTAL AIR. A DECENT DAY WITH HIGH TEMPERATURES STILL NEAR CLIMATOLOGY IF NOT EVEN A TOUCH ABOVE. FRONTAL ZONE WILL BE SITUATED TO OUR SOUTH...BUT CLOSE ENOUGH FOR MID TO HIGH LEVEL CLOUDS TO HANG AROUND FOR THE SOUTHERN ZONES. TOWARDS LAKE PLAIN AND MOHAWK VALLEY...PLENTY OF SUN. FRONTAL ZONE LIFTS BACK NORTHWARD WEDNESDAY NIGHT...WITH CLOUDS BUT ONLY SLIGHT TO LOW CHANCES OF LIGHT SHOWERS DUE TO UPPER RIDGING AND THUS LACK OF LIFT. THIS OPENS THE DOOR TO WARM RETURN FLOW AGAIN THURSDAY...WITH EXPECTED HIGHS IN THE 60S TO LOW 70S /WARMEST FOR LAKE PLAIN TO SYRACUSE COURTESY OF DOWNSLOPING/. 1000-500MB THICKNESSES SURGE INTO THE 560S DECAMETER RANGE. THURSDAY LOOKS MAINLY DRY...BUT WITH A CAVEAT. WITH UPPER RIDGE AXIS ALREADY SHIFTING EAST THURSDAY...WE GET ON EDGE OF QUICK SOUTHWESTERLY FLOW WHICH MAY BE RIDDLED WITH LITTLE SHORTWAVES. ODDLY ENOUGH...THE 00Z NAM EVEN SUGGESTS ONE OF THOSE WAVES IMPACTING THE CENTRAL SOUTHERN TIER THURSDAY EVENING WITH SHOWERS COUPLED WITH INSTABILITY. 06Z NAM THOUGH IS BACKING OFF THIS IDEA...WHILE OTHER MODELS KEEP INSTABILITY MUCH FARTHER WEST DUE TO FAIRLY STABLE LOW LEVELS FROM EARLIER MARINE-INFLUENCED LAYER ADVECTING IN WEDNESDAY NIGHT/THURSDAY. MAINLY 50S FOR LOWS THURSDAY NIGHT...WITH ONLY SLIGHT CHANCE POPS AT BEST...AS WE AWAIT NEXT PROGRESSIVE COLD FRONT WHICH WILL STILL BE WELL TO THE WEST /BUT INBOUND FOR FRIDAY/. && .LONG TERM /FRIDAY THROUGH MONDAY/... 3 PM MON UPDATE... ONLY MINIMAL CHGS MADE TO THE GRIDS ATTM...AS THE LARGE-SCALE PATN IN THE MODELS REMAINS SIMILAR. THE MAIN FEATURE TO WATCH EARLY IN THE PD IS A FAIRLY STG AND PROGRESSIVE COLD FRNT...SLATED TO COME THROUGH NY/PA BY FRI EVE. WE`LL CONTINUE TO ADVERTISE LIKELY POPS THIS PD FOR SHWRS. CONVECTIVE EVOLUTION REMAINS UNCERTAIN...OWING TO THE DEGREE OF DESTABILIZATION AHD OF THE FRNT. FOR NOW...WE`VE THROWN IN A CHC OF TSTMS...TO GO ALG WITH THE LIKELIHOOD OF SHWRS. AFTERWARDS...DRIER AIR WILL GRADUALLY FILTER IN...AS A SFC HIGH BUILDS OUT OF S-CNTRL CANADA. A FEW -SHRA/SPRINKLES COULD LINGER FRI NGT...PERHAPS EVEN INTO EARLY SAT...UNDERNEATH THE SRN END OF AN UPR-LVL TROUGH. OTHWS...THOUGH...THE WEEKEND INTO EARLY NEXT WEEK LOOKS DRY AND COOL...FROM THIS EARLY VANTAGE PT. PREV DISC... THE PERIOD BEGINS WITH A JET DIGGING A SHARP TROF INTO THE SOUTHERN PLAINS, BRINGING MUCH BELOW AVERAGE TEMPS TO THE CENTRAL U.S. AN EASTERN RIDGE DEVELOPS IN RESPONSE, WITH AN ACTIVE WEATHER PATTERN DEVELOPING IN THE SOUTHWESTERLY FLOW UP THE BACK SIDE OF THE RIDGE FROM IL/MO TO THE LOWER GREAT LAKES. STORMS RIDING UP THROUGH THE GREAT LAKES WILL HELP PULL WARM/MOIST AIR INTO NY/PA. THIS WILL LEAD TO A SHOWERY, MILD PATTERN AT THE ONSET OF THE LONG TERM PERIOD. A GREAT LAKES CYCLONE INTENSIFIES OVER NORTHERN MICHIGAN ON FRIDAY, WHILE AN ATLANTIC ANTICYCLONE BUILDS. PRESSURE GRADIENT STRENGTHENS AS A RESULT THROUGH NY/PA. PRECIPITATION TIMING AND CLOUD COVER WILL HAVE A LOT TO SAY ABOUT MAX TEMPS COME FRIDAY. 925MB TEMPS OF 15-17C ARE PROGGED BY ECMWF TO EXTEND THROUGH UPSTATE NY BY 18Z. CLOUDS ARE LIKELY TO SUPPRESS MAXES, BUT ANY BREAKS WILL ALLOW TEMPS TO PUSH THROUGH THE 70S AND ENHANCE INSTABILITY AHEAD OF COLD FRONT. UNTIL INSTABILITY CAN BE BETTER PROGGED, WILL STICK TO FORECAST FOR SHOWERS AND JUST A CHANCE OF THUNDER. COOLER/DRIER AIR FOLLOWS THE COLD FRONT FOR THE WEEKEND. && .AVIATION /17Z TUESDAY THROUGH SATURDAY/... DRY OVERCAST CONDITIONS ARE EXPECTED THROUGH THIS MORNING. CIGS WILL BE MOSTLY VFR WITH OCCASIONAL MVFR AROUND 12Z AT ELM/BGM/AVP. SHOWERS WILL DEVELOP BY EARLY AFTERNOON ACROSS NY STATE AND LATER THIS AFTERNOON IN NORTHEAST PA. A FEW HVY DOWNPOURS WITH SOME THUNDER AND LIGHTNING WILL BE POSSIBLE LATER THIS AFTERNOON ESPECIALLY AT AVP... BUT DURATION AND PROBABILITY FOR THIS IS SMALL ENOUGH SO THAT IT IS NOT INCLUDED IN THE TAFS AT THIS TIME. SHOWERS WILL END TUESDAY EVENING WITH VFR CONDITIONS RETURNING. WINDS WILL BE FROM THE SOUTH-SOUTHWEST INCREASING TO 10 TO 20 KTS WITH GUSTS AS HIGH AS 30 KTS TODAY... SHIFTING TO NORTHWEST AT 10 TO 20 KTS LATE THIS AFTERNOON THROUGH THIS EVENING THEN DIMINISHING TO LESS THAN 10 KTS LATER TUESDAY NIGHT. .OUTLOOK... WED THROUGH SAT...MOSTLY VFR. LWR CIGS PSBL THU/FRI AM...AND RESTRICTIONS PSBL FROM SHRA/TSRA FRI AFTN/EVE. && .BGM WATCHES/WARNINGS/ADVISORIES... PA...NONE. NY...NONE. && $$ SYNOPSIS...MDP NEAR TERM...CMG/MDP SHORT TERM...MDP LONG TERM...DJP/MLJ AVIATION...MSE
AREA FORECAST DISCUSSION
NWS BUFFALO NY
1104 AM EDT TUE APR 16 2013 .SYNOPSIS... A COLD FRONT WILL CROSS THE REGION TODAY ALONG WITH SOME SHOWERS... WITH A THUNDERSTORM ALSO POSSIBLE SOUTH OF BUFFALO AND ROCHESTER. FOLLOWING THE FRONT...SEASONABLY COOLER WEATHER WILL RETURN FOR TONIGHT AND WEDNESDAY...BEFORE MUCH WARMER AIR SURGES BACK INTO THE REGION IN TIME FOR THURSDAY ALONG WITH THE CHANCE FOR SOME ADDITIONAL SHOWERS. && .NEAR TERM /THROUGH TONIGHT/... DURING THE COURSE OF TODAY...LOW PRESSURE WILL TRACK ACROSS CENTRAL QUEBEC PROVENCE AND RAPIDLY EJECT NORTHEASTWARD TO LABRADOR...AND IN THE PROCESS WILL SLOWLY PUSH ITS TRAILING COLD FRONT SOUTHEASTWARD ACROSS NEW YORK STATE. AT 1100 AM...THIS FRONT WAS JUST NORTHWEST OF LAKE ERIE AND ONTARIO...WITH GOOD MODEL AGREEMENT THAT THE FRONT WILL MOVE ACROSS WESTERN NEW YORK THIS AFTERNOON. RADAR SHOWS SHOWERS AND THUNDERSTORMS HAVE DEVELOPED OUT AHEAD OF THIS FRONTAL BOUNDARY...WITH STEADY SHOWERS ACROSS MOST OF NEW YORK WEST OF ROCHESTER. WHILE SOME OF THE 00Z/06 GUIDANCE STRUGGLED TO FORECAST EXACTLY WHERE CONVECTION WOULD BREAK OUT...THE LATEST RUNS OF THE HRRR DEPICT CURRENT CONDITIONS FAIRLY WELL...AND THUS PROVIDES FAIRLY GOOD GUIDANCE FOR THE REMAINDER OF THE DAY. FOLLOWING THIS...EXPECT SHOWERS TO CONTINUE TO MOVE RAPIDLY ENE...BRINGING AT LEAST SOME PRECIPITATION TO NEARLY ALL OF THE REGION THROUGH EARLY AFTERNOON. HEAVIEST SHOWERS WILL BE SOUTH...WHERE THERE STILL ARE QUITE A FEW LIGHTNING STRIKES. THIS AREA SHOULD MOVE THROUGH RATHER RAPIDLY...BUT THE HRRR (NOW WITH SUPPORT FROM THE 12Z NAM) SUGGESTS THAT ANOTHER ROUND OF SHOWERS AND POSSIBLY THUNDERSTORMS WILL DEVELOP RIGHT ON THE FRONT. TO DO THIS WILL TAKE A MODEST CONTRIBUTION FROM DAYTIME HEATING ACROSS THE FINGER LAKES AND EASTERN LAKE ONTARIO REGIONS...EXTENDING INTO CENTRAL PORTIONS OF THE STATE. IF THIS DOES OCCUR...THIS WILL NOT DEVELOP UPSTREAM...RATHER SHOWERS WOULD DEVELOP ACROSS THE ABOVE MENTIONED REGIONS LATE THIS AFTERNOON. QPFS WILL VARY...WITH MOST AREAS LIKELY TO SEE A TENTH OF AN INCH OR TWO...WITH LOCALLY HIGHER AMOUNTS TO A HALF INCH IN THUNDERSTORMS. OTHERWISE...THE DAY WILL GET OFF TO A WARM AND BREEZY START. TEMPERATURES WILL REMAIN IN THE 60S AHEAD OF THE RAIN SHOWERS...WITH HIGHS IN THE UPPER 60S LIKELY IN THE FINGER LAKES REGION WHERE RAIN WILL HOLD OFF A BIT LONGER. MEANWHILE...SOUTHERLY WINDS WILL CONTINUE TO GUST TO 30 TO 35 MPH IN MOST LOCATIONS...WITH GUSTS TO 40 MPH ACROSS HIGHER TERRAIN AND IN THE BLACK RIVER VALLEY. LATE THIS AFTERNOON THROUGH TONIGHT...THE FRONTAL BOUNDARY WILL GET SUPPRESSED FURTHER SOUTH TO THE MASON/DIXON LINE AS HIGH PRESSURE AND MUCH DRIER AIR BRIEFLY RIDGES SOUTHEAST FROM NORTHERN ONTARIO PROVINCE. FOR OUR AREA...THIS WILL RESULT IN ANY LINGERING SHOWER CHANCES ENDING FROM NORTHWEST TO SOUTHEAST LATE THIS AFTERNOON AND EVENING FOLLOWED BY DRY WEATHER THE REMAINDER OF THE NIGHT...THOUGH SOME CLOUDS WILL LINGER ACROSS AREAS SOUTH OF LAKE ONTARIO...WHICH WILL BE CLOSER TO THE SLOWLY DEPARTING FRONTAL ZONE. AS FOR TEMPS... COOLER AIR FILTERING IN BEHIND THE FRONT WILL RESULT IN TEMPS FALLING BACK TO THE UPPER 30S TO LOWER 40S SOUTH OF LAKE ONTARIO... AND TO THE LOWER-MID 30S ACROSS THE NORTH COUNTRY WHERE THERE WILL BE LESS CLOUD COVER. && .SHORT TERM /WEDNESDAY THROUGH FRIDAY NIGHT/... A PROGRESSIVE HIGH AMPLITUDE FLOW WILL BE FOUND ACROSS THE UNITED STATES DURING THIS PERIOD...WITH THE LOWER GREAT LAKES REGION BEING FORTUNATE ENOUGH TO BE FOUND ON THE WARM SIDE OF AN EXPANSIVE RIDGE. THIS WILL LEAD TO SEASONABLE CONDITIONS ON WEDNESDAY BEFORE ANOMALOUS WARMTH RETURNS FOR THURSDAY AND FRIDAY. TEMPERATURES AT THAT TIME COULD EASILY CLIMB TO MORE THAN 20 DEGREES F ABOVE NORMAL VALUES. IT IS NOT OUT OF THE QUESTION THAT THE WARMER VALLEYS COULD EVEN TICKLE THE 80 DEGREE MARK ON THURSDAY. IN TERMS OF PCPN...THE BULK OF THIS PERIOD WILL BE RAIN-FREE. WHILE THERE WILL BE THE CHANCE FOR SOME NUISANCE LIGHT SHOWERS AS THE WARMER AIR WORKS INTO OUR REGION WEDNESDAY NIGHT AND THURSDAY...THE HIGHEST CHANCE FOR ANY ADVERSE WEATHER WILL COME FRIDAY AFTERNOON AND NIGHT WHEN A STRONG COLD FRONT WILL PLOW ACROSS THE LOWER GREAT LAKES. THIS FEATURE COULD END UP GENERATING OUR FIRST WIDESPREAD SEVERE WEATHER OUTBREAK. SOME DETAILS... HIGH PRESSURE CENTERED OVER NORTHERN ONTARIO ON WEDNESDAY WILL ARCH ACROSS THE LOWER GREAT LAKES AND NEW ENGLAND TO PROVIDE US WITH FAIR SEASONABLE CONDITIONS. THE SUNNIEST CONDITIONS WILL BE FOUND ACROSS THE EASTERN LAKE ONTARIO REGION WHILE SOME HIGH AND MID LEVEL CLOUDS CAN BE EXPECTED OVER THE FAR WESTERN COUNTIES. GIVEN THE LIGHT NORTHERLY FLOW...THE COOLEST WEATHER WILL LIKELY BE FOUND OVER THE COUNTIES BORDERING THE SOUTH SHORE OF LK ONTARIO WHERE READINGS WILL STRUGGLE INTO THE LOW 50S. ELSEWHERE...HIGHS SHOULD BE CLOSE TO THEIR SEASONABLE NORMS OF 55 TO 60. AS THE LARGE SFC HIGH MOVES EAST ACROSS QUEBEC WEDNESDAY NIGHT...A DEEP INVERTED TROUGH WILL EXTEND FROM THE CENTRAL PLAINS NORTHEAST ACROSS THE UPPER GREAT LAKES. A DEEP SOUTHERLY FLOW WILL DEVELOP BETWEEN THESE SYSTEMS...WITH STRONG WARM ADVECTION FOUND OVER THE GREAT LAKES REGION. THE LEADING EDGE OF THE WARMER AIRMASS (WARM FRONT) MAY GENERATE SOME LIGHT SHOWERS/SPRINKLES ACROSS OUR FORECAST AREA IN THE PROCESS...WITH MORE WIDESPREAD SHRA/TSRA REMAINING OVER UPPER ONTARIO AND THE UPPER GREAT LAKES. THE SOUTHERLY FLOW WILL INTENSIFY OVER THE LOWER GREAT LAKES AND OHIO VALLEY ON THURSDAY AS THE AFOREMENTIONED WARM FRONT WILL LIFT FROM THE THOUSAND ISLANDS REGION TO SOUTHERN QUEBEC. THIS WILL ALLOW OUR SKIES TO PARTIALLY CLEAR DURING THE COURSE OF THURSDAY...MUCH LIKE THEY DID YESTERDAY (MONDAY) WHEN TEMPERATURES REACHED INTO THE 70S. SPEAKING OF WHICH...H85 TEMPS WILL JUMP TO AROUND 14C BY THURSDAY AFTERNOON AND THIS WILL EASILY SUPPORT DAYTIME HIGHS IN THE MID 70S WITH 80 DEGREE READINGS NOT OUT OF THE QUESTION IN THE WARMER VALLEYS. WARM AND BREEZY CONDITIONS WILL THEN BE FOUND ACROSS THE FORECAST AREA THURSDAY NIGHT AS DEEPENING LOW PRESSURE WILL LIFT TO LOWER MICHIGAN WHILE SWEEPING A STRONG COLD FRONT AND ITS ASSOCIATED SEVERE WEATHER ACROSS THE OHIO AND TENNESSEE VALLEYS. FOR OUR REGION THOUGH...WE SHOULD BE MAINLY DRY AND QUITE MILD WITH TEMPERATURES HAVING TROUBLE FALLING BELOW 60. IT WILL BE A LITTLE ON THE HUMID SIDE AS WELL...MAKING IT FEEL MORE LIKE A NIGHT IN MID-LATE JUNE. FRIDAY WILL FEATURE VERY UNSETTLED WEATHER AS THE DEEP SFC LOW TO OUR WEST WILL PUSH ITS STRONG COLD FRONT ACROSS MUCH OF OUR REGION. FROM THIS VANTAGE POINT...GUIDANCE HAS BEEN CONSISTENT WITH BRINGING THE FRONT ACROSS WESTERN NEW YORK DURING THE AFTERNOON AND EVENING. IF THIS TIMING HOLDS UP...TEMPERATURES SHOULD BE ABLE TO JUMP BACK INTO THE 70S BEFORE THE THICKER CLOUD COVER AND FRONTAL PCPN MOVES IN. SPEAKING OF WHICH...GIVEN THE STRONG DYNAMICS OF THE SYNOPTIC SYSTEM AND THE PRESENCE OF A 60-70KT LOW LEVEL JET...WOULD ANTICIPATE AT LEAST THE THREAT FOR STRONG TO SEVERE THUNDERSTORMS AHEAD/DURING THE FRONTAL PASSAGE. WHILE GUIDANCE IS NOT DEPICTING SIGNIFICANT INSTABILITY...CONVECTION COULD EASILY BE SUPPORTED BY THE STRENGTH OF THE UNDERLYING SYNOPTICS. THE WIND PROFILE AHEAD OF THE FRONT DEPICTS ALOT OF SHEAR AS WELL...SO THIS IS A VALID CONCERN. WILL MENTION THIS THREAT IN THE HAZARDOUS WEATHER OUTLOOK. AS IF THE POTENTIAL FOR STRONG TO SEVERE THUNDERSTORMS IS NOT ENOUGH...THE STRONG LOW LEVEL JET AND FAVORABLE TRACK OF THE DEEP SFC LOW FROM LOWER MICHIGAN AND LAKE HURON TO SOUTHERN QUEBEC WILL SET THE STAGE FOR A SYNOPTIC WIND EVENT. ADVISORY CRITERIA SOUTHERLY WINDS WILL BE POSSIBLE AHEAD OF THE FRONT ACROSS THE HIGHER TERRAIN...THEN IN THE WAKE OF THE FRONT...THERE WILL BE AN 8 HOUR PERIOD WHERE SOUTHWEST WINDS WITHIN THE COLD ADVECTION COULD PRODUCE SFC WIND GUSTS IN EXCESS OF 50 MPH DOWNWIND OF LK ERIE LATE FRIDAY AFTERNOON AND THE FIRST HALF OF FRIDAY NIGHT. STAY TUNED. && .LONG TERM /SATURDAY THROUGH MONDAY/... NOTABLY COOLER WEATHER WILL CHARACTERIZE THIS PERIOD AS SEASONABLY COOL AIR WILL ACCOMPANY EXPANSIVE HIGH PRESSURE FROM THE NORTHERN PLAINS. ON SATURDAY...HIGH PRESSURE WILL GRADUALLY BUILD ACROSS THE UPPER GREAT LAKES WHILE A DEEP STORM SYSTEM WILL DRIFT TO COASTAL QUEBEC. THIS WILL KEEP A RELATIVELY TIGHT PRESSURE GRADIENT ACROSS OUR REGION SO THE STRONG WINDS FROM FRIDAY NIGHT WILL ONLY SLOWLY SUBSIDE DURING THE COURSE OF SATURDAY. THE GUSTY WINDS AND MUCH COOLER AIRMASS WILL MAKE FOR A CHILLY DAY AS TEMPS WILL STRUGGLE TO CLIMB INTO THE MID TO UPPER 40S. THERE COULD ALSO BE A COUPLE LEFTOVER SHOWERS THROUGH MIDDAY...MAINLY FOR SITES EAST OF ROCHESTER. THE EXPANSIVE SFC HIGH WILL BUILD ACROSS OUR REGION SATURDAY NIGHT AND SUNDAY. THIS WILL PROVIDE US WITH MAINLY CLEAR SKIES FOR THE SECOND HALF OF THE WEEKEND...ALTHOUGH TEMPERATURES WILL STILL BE SOME 5 TO 10 DEG F BELOW NORMAL. THE CHILL WILL BE TEMPERED ON SUNDAY THOUGH WITH AMPLE SUNSHINE. FOR MONDAY...THE CENTER OF THE SFC HIGH WILL MOVE TO THE CANADIAN MARITIMES. THE RETURN FLOW AROUND THE HIGH WILL PROMOTE SOME WEAK WARM ADVECTION OVER THE LOWER GREAT LAKES SO THAT TEMPERATURES WILL CLIMB BACK TO NEAR NORMAL LEVELS FOR MONDAY. && .AVIATION /15Z TUESDAY THROUGH SATURDAY/... THROUGH 15Z...AN INITIAL AREA OF SHOWERS WILL MOVE ACROSS THE REGION THROUGH 18Z...WITH THIS LIKELY TO LOWER CONDITIONS TO MVFR IN LOWER CIGS. THE FRONT WILL FOLLOW THIS...POSSIBLY SPARKING ANOTHER ROUND OF SHOWERS. EXPECT MVFR CONDITIONS TO PERSIST UNTIL BEHIND THE FRONT WHEN DRIER AIR BUILDS IN THIS EVENING. THERE IS A CONTINUED CHANCE FOR THUNDERSTORMS THROUGH THIS AFTERNOON...MAINLY TO THE SOUTH NEAR JHW...HOWEVER AN ISOLATED TSTM CANNOT COMPLETELY BE RULED OUT AT ANY LOCATION. DRIER AIR WILL CONTINUE TO BUILD IN OVERNIGHT...WITH VFR CONDITIONS EXPECTED. OUTLOOK... WEDNESDAY...MAINLY VFR. WEDNESDAY NIGHT AND THURSDAY...VFR/MVFR WITH A CHANCE OF SHOWERS. FRIDAY...DETERIORATION TO MVFR WITH SHOWERS BECOMING LIKELY ALONG WITH A CHANCE OF THUNDERSTORMS...SOME OF WHICH COULD PRODUCE GUSTY WINDS. SATURDAY...VFR/MVFR WITH A CHANCE OF SHOWERS. && .MARINE... IN ADVANCE OF A COLD FRONT...SOUTHERLY WINDS TO 15 TO 25 KNOTS WILL AFFECT EASTERN PORTIONS OF LAKE ERIE AND ONTARIO THIS MORNING...FOR WHICH SMALL CRAFT ADVISORIES WILL BE IN PLACE. FOLLOWING THE FRONTAL PASSAGE...WINDS WILL VEER TO WESTERLY AND DIMINISH THIS AFTERNOON... THEN WILL BECOME RELATIVELY LIGHT FOR TONIGHT AND WEDNESDAY AS HIGH PRESSURE BRIEFLY NOSES SOUTHEASTWARD ACROSS THE REGION. IT SHOULD ALSO BE NOTED THAT WHILE THE FRONT WILL MAINLY JUST PRODUCE SOME SHOWERS TODAY...A THUNDERSTORM OR TWO WILL ALSO BE POSSIBLE ACROSS LAKE ERIE. && .BUF WATCHES/WARNINGS/ADVISORIES... NY...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 4 PM EDT THIS AFTERNOON FOR LEZ040- 041. SMALL CRAFT ADVISORY UNTIL 4 PM EDT THIS AFTERNOON FOR LOZ044-045. && $$ SYNOPSIS...JJR NEAR TERM...APFFEL/JJR SHORT TERM...RSH LONG TERM...RSH AVIATION...APFFEL/JJR MARINE...APFFEL/JJR
AREA FORECAST DISCUSSION
NWS BUFFALO NY
946 AM EDT TUE APR 16 2013 .SYNOPSIS... A COLD FRONT WILL CROSS THE REGION TODAY ALONG WITH SOME SHOWERS... WITH A THUNDERSTORM ALSO POSSIBLE SOUTH OF BUFFALO AND ROCHESTER. FOLLOWING THE FRONT...SEASONABLY COOLER WEATHER WILL RETURN FOR TONIGHT AND WEDNESDAY...BEFORE MUCH WARMER AIR SURGES BACK INTO THE REGION IN TIME FOR THURSDAY ALONG WITH THE CHANCE FOR SOME ADDITIONAL SHOWERS. && .NEAR TERM /THROUGH TONIGHT/... DURING THE COURSE OF TODAY...LOW PRESSURE OVER CENTRAL ONTARIO PROVINCE WILL RAPIDLY EJECT NORTHEASTWARD TO LABRADOR...AND IN THE PROCESS WILL SLOWLY PUSH ITS TRAILING COLD FRONT SOUTHEASTWARD ACROSS NEW YORK STATE. AT 900 AM...THIS FRONT WAS LOCATED BETWEEN LAKE HURON AND LAKE ERIE AND ONTARIO...WITH GOOD MODEL AGREEMENT THAT THE FRONT WILL MOVE ACROSS WESTERN NEW YORK THIS AFTERNOON. RADAR SHOWS SHOWERS AND THUNDERSTORMS HAVE DEVELOPED OUT AHEAD OF THIS FRONTAL BOUNDARY...WITH THE STEADIEST OF THIS TO MOVE INTO WESTERN PORTIONS OF THE SOUTHERN TIER LATE THIS MORNING. WHILE SOME OF THE 00Z/06 GUIDANCE STRUGGLED TO FORECAST EXACTLY WHERE CONVECTION WOULD BREAK OUT...THE LATEST RUNS OF THE HRRR DEPICTS CURRENT CONDITIONS FAIRLY WELL...AND THUS PROVIDES FAIRLY GOOD GUIDANCE FOR THE NEXT FEW HOURS. FOLLOWING THIS...EXPECT SHOWERS TO FILL IN TO THE NORTH LATE THIS MORNING...BRINGING AT LEAST SOME PRECIPITATION TO NEARLY ALL OF THE REGION THROUGH EARLY AFTERNOON. HEAVIEST SHOWERS WILL BE SOUTH...WHERE THERE STILL ARE QUITE A FEW LIGHTNING STRIKES. NAM/GFS MODEL GUIDANCE SHOWS CONTINUED ELEVATED INSTABILITY IN SOUTHERN SECTIONS...AND THIS IS CONSISTENT WITH HRRR REFLECTIVITY FORECASTS. THE ONLY QUESTION IS HOW FAR NORTH WILL THIS MAKE IT...WITH THE HRRR FORECASTING EXPANDING SHOWER ACTIVITY THIS AFTERNOON ACROSS CENTRAL NEW YORK...LIKELY DUE TO SOME LIMITED DAYTIME HEATING OUT AHEAD OF THE FRONT. FOR NOW...KEEP THE MENTION OF THUNDER SOUTH OF I-90. QPFS WILL VARY...WITH MOST AREAS LIKELY TO SEE A TENTH OF AN INCH OR TWO...WITH LOCALLY HIGHER AMOUNTS TO A HALF INCH IN THUNDERSTORMS. OTHERWISE...THE DAY WILL GET OFF TO A WARM AND BREEZY START. TEMPERATURES WILL REMAIN IN THE 60S AHEAD OF THE RAIN SHOWERS...WITH HIGHS IN THE UPPER 60S LIKELY IN THE FINGER LAKES REGION WHERE RAIN WILL HOLD OFF A BIT LONGER. MEANWHILE...SOUTHERLY WINDS WILL CONTINUE TO GUST TO 30 TO 35 MPH IN MOST LOCATIONS...WITH GUSTS TO 40 MPH ACROSS HIGHER TERRAIN AND IN THE BLACK RIVER VALLEY. LATE THIS AFTERNOON THROUGH TONIGHT...THE FRONTAL BOUNDARY WILL GET SUPPRESSED FURTHER SOUTH TO THE MASON/DIXON LINE AS HIGH PRESSURE AND MUCH DRIER AIR BRIEFLY RIDGES SOUTHEAST FROM NORTHERN ONTARIO PROVINCE. FOR OUR AREA...THIS WILL RESULT IN ANY LINGERING SHOWER CHANCES ENDING FROM NORTHWEST TO SOUTHEAST LATE THIS AFTERNOON AND EVENING FOLLOWED BY DRY WEATHER THE REMAINDER OF THE NIGHT...THOUGH SOME CLOUDS WILL LINGER ACROSS AREAS SOUTH OF LAKE ONTARIO...WHICH WILL BE CLOSER TO THE SLOWLY DEPARTING FRONTAL ZONE. AS FOR TEMPS... COOLER AIR FILTERING IN BEHIND THE FRONT WILL RESULT IN TEMPS FALLING BACK TO THE UPPER 30S TO LOWER 40S SOUTH OF LAKE ONTARIO... AND TO THE LOWER-MID 30S ACROSS THE NORTH COUNTRY WHERE THERE WILL BE LESS CLOUD COVER. && .SHORT TERM /WEDNESDAY THROUGH FRIDAY NIGHT/... A PROGRESSIVE HIGH AMPLITUDE FLOW WILL BE FOUND ACROSS THE UNITED STATES DURING THIS PERIOD...WITH THE LOWER GREAT LAKES REGION BEING FORTUNATE ENOUGH TO BE FOUND ON THE WARM SIDE OF AN EXPANSIVE RIDGE. THIS WILL LEAD TO SEASONABLE CONDITIONS ON WEDNESDAY BEFORE ANOMALOUS WARMTH RETURNS FOR THURSDAY AND FRIDAY. TEMPERATURES AT THAT TIME COULD EASILY CLIMB TO MORE THAN 20 DEGREES F ABOVE NORMAL VALUES. IT IS NOT OUT OF THE QUESTION THAT THE WARMER VALLEYS COULD EVEN TICKLE THE 80 DEGREE MARK ON THURSDAY. IN TERMS OF PCPN...THE BULK OF THIS PERIOD WILL BE RAIN-FREE. WHILE THERE WILL BE THE CHANCE FOR SOME NUISANCE LIGHT SHOWERS AS THE WARMER AIR WORKS INTO OUR REGION WEDNESDAY NIGHT AND THURSDAY...THE HIGHEST CHANCE FOR ANY ADVERSE WEATHER WILL COME FRIDAY AFTERNOON AND NIGHT WHEN A STRONG COLD FRONT WILL PLOW ACROSS THE LOWER GREAT LAKES. THIS FEATURE COULD END UP GENERATING OUR FIRST WIDESPREAD SEVERE WEATHER OUTBREAK. SOME DETAILS... HIGH PRESSURE CENTERED OVER NORTHERN ONTARIO ON WEDNESDAY WILL ARCH ACROSS THE LOWER GREAT LAKES AND NEW ENGLAND TO PROVIDE US WITH FAIR SEASONABLE CONDITIONS. THE SUNNIEST CONDITIONS WILL BE FOUND ACROSS THE EASTERN LAKE ONTARIO REGION WHILE SOME HIGH AND MID LEVEL CLOUDS CAN BE EXPECTED OVER THE FAR WESTERN COUNTIES. GIVEN THE LIGHT NORTHERLY FLOW...THE COOLEST WEATHER WILL LIKELY BE FOUND OVER THE COUNTIES BORDERING THE SOUTH SHORE OF LK ONTARIO WHERE READINGS WILL STRUGGLE INTO THE LOW 50S. ELSEWHERE...HIGHS SHOULD BE CLOSE TO THEIR SEASONABLE NORMS OF 55 TO 60. AS THE LARGE SFC HIGH MOVES EAST ACROSS QUEBEC WEDNESDAY NIGHT...A DEEP INVERTED TROUGH WILL EXTEND FROM THE CENTRAL PLAINS NORTHEAST ACROSS THE UPPER GREAT LAKES. A DEEP SOUTHERLY FLOW WILL DEVELOP BETWEEN THESE SYSTEMS...WITH STRONG WARM ADVECTION FOUND OVER THE GREAT LAKES REGION. THE LEADING EDGE OF THE WARMER AIRMASS (WARM FRONT) MAY GENERATE SOME LIGHT SHOWERS/SPRINKLES ACROSS OUR FORECAST AREA IN THE PROCESS...WITH MORE WIDESPREAD SHRA/TSRA REMAINING OVER UPPER ONTARIO AND THE UPPER GREAT LAKES. THE SOUTHERLY FLOW WILL INTENSIFY OVER THE LOWER GREAT LAKES AND OHIO VALLEY ON THURSDAY AS THE AFOREMENTIONED WARM FRONT WILL LIFT FROM THE THOUSAND ISLANDS REGION TO SOUTHERN QUEBEC. THIS WILL ALLOW OUR SKIES TO PARTIALLY CLEAR DURING THE COURSE OF THURSDAY...MUCH LIKE THEY DID YESTERDAY (MONDAY) WHEN TEMPERATURES REACHED INTO THE 70S. SPEAKING OF WHICH...H85 TEMPS WILL JUMP TO AROUND 14C BY THURSDAY AFTERNOON AND THIS WILL EASILY SUPPORT DAYTIME HIGHS IN THE MID 70S WITH 80 DEGREE READINGS NOT OUT OF THE QUESTION IN THE WARMER VALLEYS. WARM AND BREEZY CONDITIONS WILL THEN BE FOUND ACROSS THE FORECAST AREA THURSDAY NIGHT AS DEEPENING LOW PRESSURE WILL LIFT TO LOWER MICHIGAN WHILE SWEEPING A STRONG COLD FRONT AND ITS ASSOCIATED SEVERE WEATHER ACROSS THE OHIO AND TENNESSEE VALLEYS. FOR OUR REGION THOUGH...WE SHOULD BE MAINLY DRY AND QUITE MILD WITH TEMPERATURES HAVING TROUBLE FALLING BELOW 60. IT WILL BE A LITTLE ON THE HUMID SIDE AS WELL...MAKING IT FEEL MORE LIKE A NIGHT IN MID-LATE JUNE. FRIDAY WILL FEATURE VERY UNSETTLED WEATHER AS THE DEEP SFC LOW TO OUR WEST WILL PUSH ITS STRONG COLD FRONT ACROSS MUCH OF OUR REGION. FROM THIS VANTAGE POINT...GUIDANCE HAS BEEN CONSISTENT WITH BRINGING THE FRONT ACROSS WESTERN NEW YORK DURING THE AFTERNOON AND EVENING. IF THIS TIMING HOLDS UP...TEMPERATURES SHOULD BE ABLE TO JUMP BACK INTO THE 70S BEFORE THE THICKER CLOUD COVER AND FRONTAL PCPN MOVES IN. SPEAKING OF WHICH...GIVEN THE STRONG DYNAMICS OF THE SYNOPTIC SYSTEM AND THE PRESENCE OF A 60-70KT LOW LEVEL JET...WOULD ANTICIPATE AT LEAST THE THREAT FOR STRONG TO SEVERE THUNDERSTORMS AHEAD/DURING THE FRONTAL PASSAGE. WHILE GUIDANCE IS NOT DEPICTING SIGNIFICANT INSTABILITY...CONVECTION COULD EASILY BE SUPPORTED BY THE STRENGTH OF THE UNDERLYING SYNOPTICS. THE WIND PROFILE AHEAD OF THE FRONT DEPICTS ALOT OF SHEAR AS WELL...SO THIS IS A VALID CONCERN. WILL MENTION THIS THREAT IN THE HAZARDOUS WEATHER OUTLOOK. AS IF THE POTENTIAL FOR STRONG TO SEVERE THUNDERSTORMS IS NOT ENOUGH...THE STRONG LOW LEVEL JET AND FAVORABLE TRACK OF THE DEEP SFC LOW FROM LOWER MICHIGAN AND LAKE HURON TO SOUTHERN QUEBEC WILL SET THE STAGE FOR A SYNOPTIC WIND EVENT. ADVISORY CRITERIA SOUTHERLY WINDS WILL BE POSSIBLE AHEAD OF THE FRONT ACROSS THE HIGHER TERRAIN...THEN IN THE WAKE OF THE FRONT...THERE WILL BE AN 8 HOUR PERIOD WHERE SOUTHWEST WINDS WITHIN THE COLD ADVECTION COULD PRODUCE SFC WIND GUSTS IN EXCESS OF 50 MPH DOWNWIND OF LK ERIE LATE FRIDAY AFTERNOON AND THE FIRST HALF OF FRIDAY NIGHT. STAY TUNED. && .LONG TERM /SATURDAY THROUGH MONDAY/... NOTABLY COOLER WEATHER WILL CHARACTERIZE THIS PERIOD AS SEASONABLY COOL AIR WILL ACCOMPANY EXPANSIVE HIGH PRESSURE FROM THE NORTHERN PLAINS. ON SATURDAY...HIGH PRESSURE WILL GRADUALLY BUILD ACROSS THE UPPER GREAT LAKES WHILE A DEEP STORM SYSTEM WILL DRIFT TO COASTAL QUEBEC. THIS WILL KEEP A RELATIVELY TIGHT PRESSURE GRADIENT ACROSS OUR REGION SO THE STRONG WINDS FROM FRIDAY NIGHT WILL ONLY SLOWLY SUBSIDE DURING THE COURSE OF SATURDAY. THE GUSTY WINDS AND MUCH COOLER AIRMASS WILL MAKE FOR A CHILLY DAY AS TEMPS WILL STRUGGLE TO CLIMB INTO THE MID TO UPPER 40S. THERE COULD ALSO BE A COUPLE LEFTOVER SHOWERS THROUGH MIDDAY...MAINLY FOR SITES EAST OF ROCHESTER. THE EXPANSIVE SFC HIGH WILL BUILD ACROSS OUR REGION SATURDAY NIGHT AND SUNDAY. THIS WILL PROVIDE US WITH MAINLY CLEAR SKIES FOR THE SECOND HALF OF THE WEEKEND...ALTHOUGH TEMPERATURES WILL STILL BE SOME 5 TO 10 DEG F BELOW NORMAL. THE CHILL WILL BE TEMPERED ON SUNDAY THOUGH WITH AMPLE SUNSHINE. FOR MONDAY...THE CENTER OF THE SFC HIGH WILL MOVE TO THE CANADIAN MARITIMES. THE RETURN FLOW AROUND THE HIGH WILL PROMOTE SOME WEAK WARM ADVECTION OVER THE LOWER GREAT LAKES SO THAT TEMPERATURES WILL CLIMB BACK TO NEAR NORMAL LEVELS FOR MONDAY. && .AVIATION /14Z TUESDAY THROUGH SATURDAY/... THROUGH 12Z...DRY VFR WEATHER WILL CONTINUE ACROSS THE AREA...ALONG WITH AN INCREASE IN MID-LEVEL CLOUD COVER IN ADVANCE OF A COLD FRONT APPROACHING FROM THE CENTRAL GREAT LAKES. LOW LEVEL WIND SHEAR CONCERNS WILL ALSO PERSIST COURTESY OF A 50 KT SOUTHWESTERLY JET AT 1500 FEET...BEFORE INCREASING MIXING HELPS ALLEVIATE THE LLWS BETWEEN 12Z AND 14Z THIS MORNING. AFTER THAT TIME...A COLD FRONT WILL CROSS THE REGION...BRINGING A PERIOD OF SHOWERS THAT WILL FOCUS ON THE 14Z-19Z TIME FRAME ACROSS THE FAR WEST...AND 16Z-22Z FURTHER EAST. THESE WILL PROBABLY BRING A PERIOD OF MVFR CONDITIONS THAT WILL PROBABLY LINGER FOR A FEW HOURS FOLLOWING THE FROPA...BEFORE DRIER AIR WORKING IN THE CENTRAL GREAT LAKES BRINGS A RETURN TO VFR CONDITIONS LATER THIS AFTERNOON AND EARLY THIS EVENING. ONCE ESTABLISHED...THESE VFR CONDITIONS SHOULD THEN PERSIST THROUGH THE BALANCE OF THE PERIOD. OUTLOOK... WEDNESDAY...MAINLY VFR. WEDNESDAY NIGHT AND THURSDAY...VFR/MVFR WITH A CHANCE OF SHOWERS. FRIDAY...DETERIORATION TO MVFR WITH SHOWERS BECOMING LIKELY ALONG WITH A CHANCE OF THUNDERSTORMS...SOME OF WHICH COULD PRODUCE GUSTY WINDS. SATURDAY...VFR/MVFR WITH A CHANCE OF SHOWERS. && .MARINE... IN ADVANCE OF A COLD FRONT...SOUTHERLY WINDS TO 15 TO 25 KNOTS WILL AFFECT EASTERN PORTIONS OF LAKE ERIE AND ONTARIO THIS MORNING...FOR WHICH SMALL CRAFT ADVISORIES WILL BE IN PLACE. FOLLOWING THE FRONTAL PASSAGE...WINDS WILL VEER TO WESTERLY AND DIMINISH THIS AFTERNOON... THEN WILL BECOME RELATIVELY LIGHT FOR TONIGHT AND WEDNESDAY AS HIGH PRESSURE BRIEFLY NOSES SOUTHEASTWARD ACROSS THE REGION. IT SHOULD ALSO BE NOTED THAT WHILE THE FRONT WILL MAINLY JUST PRODUCE SOME SHOWERS TODAY...A THUNDERSTORM OR TWO WILL ALSO BE POSSIBLE ACROSS LAKE ERIE. && .BUF WATCHES/WARNINGS/ADVISORIES... NY...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 4 PM EDT THIS AFTERNOON FOR LEZ040- 041. SMALL CRAFT ADVISORY UNTIL 4 PM EDT THIS AFTERNOON FOR LOZ044-045. && $$ SYNOPSIS...JJR NEAR TERM...JJR SHORT TERM...RSH LONG TERM...RSH AVIATION...APFFEL/JJR MARINE...APFFEL/JJR
AREA FORECAST DISCUSSION
NWS BISMARCK ND
913 PM CDT WED APR 17 2013 .UPDATE... ISSUED AT 902 PM CDT WED APR 17 2013 SNOW BAND LINING UP ACROSS THE FAR SOUTHEAST AND FAR SOUTH CENTRAL PORTION OF THE STATE FOR THIS EVENING INTO THE EARLY MORNING. RAISED SNOW TO DEFINITE ACROSS DICKEY...MCINTOSH...AND LAMOURE COUNTIES AS WELL AS SOUTHEAST EMMONS. VISIBILITIES IN SNOW DOWN TO 3/4 MILE FROM PHILLIP TO MOBRIDGE EARLIER THIS EVENING AND THIS BAND WILL MOVE NORTHEAST INTO NORTH DAKOTA. RADARS DO SHOW SOME DECREASE IN COVERAGE/INTENSITY AND THE LATEST RUC IMPLIED THIS SNOW WILL DIMINISH LATER TONIGHT...SO SNOWFALL IN 2 INCH RANGE THERE LOOKS OK. REMAINDER OF STATE LOOKS GOOD. CLOUDS MOVING BACK INTO MINOT...BUT CLEARING NORTHWEST. UPDATE ISSUED AT 646 PM CDT WED APR 17 2013 CLEARING SKIES POKING INTO THE NORTHWEST AND NORTH CENTRAL THIS EVENING. BANDS OF HIGH CLOUDS STRETCH SOUTHWEST THROUGH NORTHEAST AND WILL OVER RUN SOME OF THE CLEARING AREAS SOUTH OF MINOT. ACROSS THE SOUTHEAST...LIGHT SNOW WILL CONTINUE ACROSS DICKEY... LAMOURE AND MCINTOSH COUNTIES THROUGH THIS EVENING. MADE SOME ADJUSTMENTS TO CLOUDS NORTH CENTRAL AND NORTHWEST. && .SHORT TERM...(THIS EVENING THROUGH THURSDAY) ISSUED AT 340 PM CDT WED APR 17 2013 FORECAST HIGHLIGHTS IN THE SHORT TERM PERIOD WILL BE CONTINUING CHANCES FOR LIGHT SNOW ACROSS THE SOUTHERN JAMES RIVER VALLEY NOW THROUGH TONIGHT AND INTO THURSDAY. CURRENTLY...A DYNAMIC UPPER LEVEL LONG WAVE TROUGH WAS OVER THE ROCKIES WITH SOUTHWEST FLOW ALOFT OVER THE NORTHERN PLAINS. MULTIPLE EMBEDDED SHORTWAVES IN THE FLOW WERE MOVING NORTHEAST FROM THE BASE OF THE TROUGH ACROSS THE SOUTHERN ROCKIES INTO THE CENTRAL AND NORTHERN PLAINS. AN UPPER LEVEL JET EXTENDS FROM THE BASE OF THE TROUGH TO CENTRAL SOUTH DAKOTA INTO NORTHERN MINNESOTA...PROVIDING THE FOCUS AREA FOR A PERSISTENT BAND OF LIGHT TO MODERATE SNOW OVER MY SOUTHEAST SINCE EARLIER THIS MORNING TILL NOW. WHILE SOME ACCUMULATIONS ARE OCCURRING...THIS IS MAINLY ON GRASSY AREAS WITH ROAD SURFACES WET THANKS TO ROAD SURFACE TEMPERATURES AT 60F OR HIGHER. DUE IN PART TO OUR RECENT SNOWFALL...HIGH BOUNDARY LAYER MOISTURE REMAINS ACROSS THE LOCAL REGION RESULTING IN A PERSISTENT STRATUS DECK STILL IN PLACE OVER MOST OF WEST AND CENTRAL NORTH DAKOTA. DO NOT SEE THIS DISSIPATING UNTIL MAYBE TOMORROW MORNING/AFTERNOON WHEN A S/WV RIDGE MOVES INTO THE STATE HELPING TO SCOUR OUT THE LOW CLOUDS. WILL CONTINUE WITH THE SPS THROUGH THIS EVENING WITH SOME ADDITIONAL LIGHT ACCUMULATIONS POSSIBLE SOUTHEAST WITH BOTH THE NAM AND RAP BRINGING ANOTHER S/WV NORTHEAST ACROSS PORTIONS OF THE JAMES BASIN THIS EVENING. ALREADY SEE THIS ENHANCED AREA OF PRECIP EAST OF THE BLACK HILLS AND WEST OF PIERRE ADVECTING NORTHEAST. WITH NIGHTFALL...ROAD SURFACE TEMPERATURES...AS THEY DID LAST NIGHT...WILL FALL TO AROUND FREEZING...SO ICY CONDITIONS ARE POSSIBLE AND WILL MENTION THIS WITHIN THE SPS. SNOW CHANCES DECREASE THURSDAY MORNING/AFTERNOON ACROSS THE SOUTHEAST AS THE UPPER JET MIGRATES EAST AND WEAK HIGH PRESSURE BUILDS IN ACROSS CENTRAL NORTH DAKOTA. WITH THE CLOUDS SCOURING OUT AND WITH THE S/WV RIDGE PROVIDING SOME WAA...HAVE FORECAST HIGHS THURSDAY NEAR 40 WEST. 30S CENTRAL AND EAST WITH A MODERATE NORTH FLOW REMAINING IN PLACE ALONG WITH A LONGER DURATION OF CLOUDS. .LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY) ISSUED AT 340 PM CDT WED APR 17 2013 NO SIGNIFICANT STORMS IN THE LONG TERM PERIOD...HOWEVER EXPECT AN ACTIVE PERIOD THROUGH SUNDAY AS PERIODIC CHANCES FOR SNOW/SLEET/RAIN OCCURS ACROSS WESTERN AND CENTRAL NORTH DAKOTA. THIS WILL RESULT IN A COUPLE OF INCHES OF MORE SNOW TO ACCUMULATE ESPECIALLY OVER NORTH CENTRAL NORTH DAKOTA THROUGH SUNDAY. H5 PATTERN FOR MID TO LATE NEXT WEEK STILL IN GOOD AGREEMENT WITH ESTABLISHING A H5 RIDGE OVER THE NORTHERN ROCKIES WITH A GRADUAL MODERATING TREND AS DENOTED IN THE H85 TEMPERATURES ACROSS MONTANA INTO WESTERN AND CENTRAL NORTH DAKOTA. BEGINNING THURSDAY NIGHT...A WEAK ALBERTA CLIPPER SYSTEM SLIDES INTO NORTHWEST NORTH DAKOTA THURSDAY NIGHT AND INTO SOUTH CENTRAL NORTH DAKOTA 12Z FRIDAY. SHORT RANGE MODELS SHOW A BAND OF LIGHT SNOW OR POSSIBLY A WINTRY MIX ORIENTED NORTHWEST TO SOUTHEAST WITH UP TO ONE INCH OF SNOW IN NORTH CENTRAL NORTH DAKOTA...FROM BOWBELLS TO STANLEY...EAST TO MINOT AND SHERWOOD. PERHAPS A DUSTING COULD OCCUR ELSEWHERE IN CENTRAL NORTH DAKOTA. LINGERING LIGHT SNOW CONTINUES INTO FRIDAY MORNING WITH THE LOW EXITING FRIDAY AFTERNOON. EXPECT A BRIEF PERIOD OF DRY WEATHER FRIDAY AFTERNOON INTO A PORTION OF FRIDAY NIGHT. FRIDAY NIGHT/SATURDAY/SUNDAY...SURFACE LOW PRESSURE/WARM FRONT IN EASTERN MONTANA WILL PROGRESS EAST...RESULTING IN DECENT ISENTROPIC ASCENT ON THE 285K-295K PRESSURE SURFACES. THIS PRODUCES HIGH CHC/LIKELY POPS BY LATE FRIDAY NIGHT WEST...AND SPREADING INTO CENTRAL NORTH DAKOTA SATURDAY. WARMER TEMPERATURES ALOFT WILL RESULT IN RAIN ACROSS SOUTHWEST NORTH DAKOTA SATURDAY...WITH LIGHT SNOW ELSEWHERE. WIDESPREAD SNOWFALL ACCUMULATIONS OF UP TO ONE INCH WILL BE COMMON...WITH A COUPLE OF INCHES FAVORING NORTH CENTRAL NORTH DAKOTA. ABOVE FREEZING ROAD TEMPERATURES DURING THE DAYLIGHT HOURS SHOULD ALLOW FOR MELTING...WITH SNOWFALL ACCUMULATIONS MAINLY ON THE GRASSY AREAS. FOR MONDAY...A NORTHERN STREAM UPPER LOW/TROUGH FOLLOWS...AND DIGS INTO WESTERN NORTH DAKOTA WITH A PRECIPITATION THREAT REMAINING WEST...SOUTH...AND EAST OF THE FORECAST AREA. THIS LOW EJECTS OUT LATE TUESDAY WITH A BUILDING H5 RIDGE DEVELOPING ALONG THE WEST COAST. THIS RIDGE SLOWLY SIDES EAST INTO THE NORTHERN ROCKIES WEDNESDAY THROUGH FRIDAY WITH A GRADUAL WARMUP. ABOVE AVERAGE TEMPERATURES LIKELY IN THE WEST BY LATE NEXT WEEK. THIS SHOULD ALSO PROMOTE A GENTLE MELT OF THE SNOWPACK UNDER A DRY WEATHER REGIME. && .AVIATION...(FOR THE 00Z TAFS THROUGH 00Z THURSDAY EVENING) ISSUED AT 902 PM CDT WED APR 17 2013 LARGE LOW PRESSURE EXTENDING FROM IOWA INTO NORTHERN MINNESOTA WILL SPREAD SNOW TO SOUTHEAST NORTH DAKOTA TONIGHT. HIGH PRESSURE ACROSS EASTERN MONTANA WILL BEGIN TO CLEAR SKIES ACROSS NORTHWEST NORTH DAKOTA. MVFR CONDITIONS EXPECTED FROM KDIK-KBIS-KJMS. VFR OR BECOMING VFR KISN-KMOT. && .BIS WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...WAA SHORT TERM...NH LONG TERM...KS AVIATION...WAA
AREA FORECAST DISCUSSION
NWS BISMARCK ND
658 PM CDT WED APR 17 2013 .UPDATE... ISSUED AT 646 PM CDT WED APR 17 2013 CLEARING SKIES POKING INTO THE NORTHWEST AND NORTH CENTRAL THIS EVENING. BANDS OF HIGH CLOUDS STRETCH SOUTHWEST THROUGH NORTHEAST AND WILL OVER RUN SOME OF THE CLEARING AREAS SOUTH OF MINOT. ACROSS THE SOUTHEAST...LIGHT SNOW WILL CONTINUE ACROSS DICKEY... LAMOURE AND MCINTOSH COUNTIES THROUGH THIS EVENING. MADE SOME ADJUSTMENTS TO CLOUDS NORTH CENTRAL AND NORTHWEST. && .SHORT TERM...(THIS EVENING THROUGH THURSDAY) ISSUED AT 340 PM CDT WED APR 17 2013 FORECAST HIGHLIGHTS IN THE SHORT TERM PERIOD WILL BE CONTINUING CHANCES FOR LIGHT SNOW ACROSS THE SOUTHERN JAMES RIVER VALLEY NOW THROUGH TONIGHT AND INTO THURSDAY. CURRENTLY...A DYNAMIC UPPER LEVEL LONG WAVE TROUGH WAS OVER THE ROCKIES WITH SOUTHWEST FLOW ALOFT OVER THE NORTHERN PLAINS. MULTIPLE EMBEDDED SHORTWAVES IN THE FLOW WERE MOVING NORTHEAST FROM THE BASE OF THE TROUGH ACROSS THE SOUTHERN ROCKIES INTO THE CENTRAL AND NORTHERN PLAINS. AN UPPER LEVEL JET EXTENDS FROM THE BASE OF THE TROUGH TO CENTRAL SOUTH DAKOTA INTO NORTHERN MINNESOTA...PROVIDING THE FOCUS AREA FOR A PERSISTENT BAND OF LIGHT TO MODERATE SNOW OVER MY SOUTHEAST SINCE EARLIER THIS MORNING TILL NOW. WHILE SOME ACCUMULATIONS ARE OCCURRING...THIS IS MAINLY ON GRASSY AREAS WITH ROAD SURFACES WET THANKS TO ROAD SURFACE TEMPERATURES AT 60F OR HIGHER. DUE IN PART TO OUR RECENT SNOWFALL...HIGH BOUNDARY LAYER MOISTURE REMAINS ACROSS THE LOCAL REGION RESULTING IN A PERSISTENT STRATUS DECK STILL IN PLACE OVER MOST OF WEST AND CENTRAL NORTH DAKOTA. DO NOT SEE THIS DISSIPATING UNTIL MAYBE TOMORROW MORNING/AFTERNOON WHEN A S/WV RIDGE MOVES INTO THE STATE HELPING TO SCOUR OUT THE LOW CLOUDS. WILL CONTINUE WITH THE SPS THROUGH THIS EVENING WITH SOME ADDITIONAL LIGHT ACCUMULATIONS POSSIBLE SOUTHEAST WITH BOTH THE NAM AND RAP BRINGING ANOTHER S/WV NORTHEAST ACROSS PORTIONS OF THE JAMES BASIN THIS EVENING. ALREADY SEE THIS ENHANCED AREA OF PRECIP EAST OF THE BLACK HILLS AND WEST OF PIERRE ADVECTING NORTHEAST. WITH NIGHTFALL...ROAD SURFACE TEMPERATURES...AS THEY DID LAST NIGHT...WILL FALL TO AROUND FREEZING...SO ICY CONDITIONS ARE POSSIBLE AND WILL MENTION THIS WITHIN THE SPS. SNOW CHANCES DECREASE THURSDAY MORNING/AFTERNOON ACROSS THE SOUTHEAST AS THE UPPER JET MIGRATES EAST AND WEAK HIGH PRESSURE BUILDS IN ACROSS CENTRAL NORTH DAKOTA. WITH THE CLOUDS SCOURING OUT AND WITH THE S/WV RIDGE PROVIDING SOME WAA...HAVE FORECAST HIGHS THURSDAY NEAR 40 WEST. 30S CENTRAL AND EAST WITH A MODERATE NORTH FLOW REMAINING IN PLACE ALONG WITH A LONGER DURATION OF CLOUDS. .LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY) ISSUED AT 340 PM CDT WED APR 17 2013 NO SIGNIFICANT STORMS IN THE LONG TERM PERIOD...HOWEVER EXPECT AN ACTIVE PERIOD THROUGH SUNDAY AS PERIODIC CHANCES FOR SNOW/SLEET/RAIN OCCURS ACROSS WESTERN AND CENTRAL NORTH DAKOTA. THIS WILL RESULT IN A COUPLE OF INCHES OF MORE SNOW TO ACCUMULATE ESPECIALLY OVER NORTH CENTRAL NORTH DAKOTA THROUGH SUNDAY. H5 PATTERN FOR MID TO LATE NEXT WEEK STILL IN GOOD AGREEMENT WITH ESTABLISHING A H5 RIDGE OVER THE NORTHERN ROCKIES WITH A GRADUAL MODERATING TREND AS DENOTED IN THE H85 TEMPERATURES ACROSS MONTANA INTO WESTERN AND CENTRAL NORTH DAKOTA. BEGINNING THURSDAY NIGHT...A WEAK ALBERTA CLIPPER SYSTEM SLIDES INTO NORTHWEST NORTH DAKOTA THURSDAY NIGHT AND INTO SOUTH CENTRAL NORTH DAKOTA 12Z FRIDAY. SHORT RANGE MODELS SHOW A BAND OF LIGHT SNOW OR POSSIBLY A WINTRY MIX ORIENTED NORTHWEST TO SOUTHEAST WITH UP TO ONE INCH OF SNOW IN NORTH CENTRAL NORTH DAKOTA...FROM BOWBELLS TO STANLEY...EAST TO MINOT AND SHERWOOD. PERHAPS A DUSTING COULD OCCUR ELSEWHERE IN CENTRAL NORTH DAKOTA. LINGERING LIGHT SNOW CONTINUES INTO FRIDAY MORNING WITH THE LOW EXITING FRIDAY AFTERNOON. EXPECT A BRIEF PERIOD OF DRY WEATHER FRIDAY AFTERNOON INTO A PORTION OF FRIDAY NIGHT. FRIDAY NIGHT/SATURDAY/SUNDAY...SURFACE LOW PRESSURE/WARM FRONT IN EASTERN MONTANA WILL PROGRESS EAST...RESULTING IN DECENT ISENTROPIC ASCENT ON THE 285K-295K PRESSURE SURFACES. THIS PRODUCES HIGH CHC/LIKELY POPS BY LATE FRIDAY NIGHT WEST...AND SPREADING INTO CENTRAL NORTH DAKOTA SATURDAY. WARMER TEMPERATURES ALOFT WILL RESULT IN RAIN ACROSS SOUTHWEST NORTH DAKOTA SATURDAY...WITH LIGHT SNOW ELSEWHERE. WIDESPREAD SNOWFALL ACCUMULATIONS OF UP TO ONE INCH WILL BE COMMON...WITH A COUPLE OF INCHES FAVORING NORTH CENTRAL NORTH DAKOTA. ABOVE FREEZING ROAD TEMPERATURES DURING THE DAYLIGHT HOURS SHOULD ALLOW FOR MELTING...WITH SNOWFALL ACCUMULATIONS MAINLY ON THE GRASSY AREAS. FOR MONDAY...A NORTHERN STREAM UPPER LOW/TROUGH FOLLOWS...AND DIGS INTO WESTERN NORTH DAKOTA WITH A PRECIPITATION THREAT REMAINING WEST...SOUTH...AND EAST OF THE FORECAST AREA. THIS LOW EJECTS OUT LATE TUESDAY WITH A BUILDING H5 RIDGE DEVELOPING ALONG THE WEST COAST. THIS RIDGE SLOWLY SIDES EAST INTO THE NORTHERN ROCKIES WEDNESDAY THROUGH FRIDAY WITH A GRADUAL WARMUP. ABOVE AVERAGE TEMPERATURES LIKELY IN THE WEST BY LATE NEXT WEEK. THIS SHOULD ALSO PROMOTE A GENTLE MELT OF THE SNOWPACK UNDER A DRY WEATHER REGIME. && .AVIATION...(FOR THE 00Z TAFS THROUGH 00Z THURSDAY EVENING) ISSUED AT 646 PM CDT WED APR 17 2013 LARGE WINTER STORM BRUSHING THE SOUTHEAST PORTION OF NORTH DAKOTA WEDNESDAY EVENING. EXPECT MVFR CONDITIONS FROM KDIK-KBIS-KJMS THROUGH 14Z. CONDITIONS BECOMING VFR AFTER 14Z. KISN WILL BE MVFR WEDNESDAY EVENING...THEN BECOME VFR AFTER 04Z. SOME UNCERTAINTY ABOUT KMOT. CURRENTLY CLEARING SKIES OVER THE NORTH CENTRAL. CONCERN THERE MAY BE RETURN TO MVFR AFTER 06Z. && .BIS WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...WAA SHORT TERM...NH LONG TERM...KS AVIATION...WAA
AREA FORECAST DISCUSSION
NWS WILMINGTON OH
804 PM EDT WED APR 17 2013 .SYNOPSIS... A POTENT SPRING STORM SYSTEM WILL EJECT NORTHEAST THROUGH THE MID MISSISSIPPI VALLEY TONIGHT THROUGH FRIDAY...BRINGING A WILD SWING IN TEMPERATURE AND THE THREAT OF STRONG TO SEVERE THUNDERSTORMS. VERY WARM CONDITIONS ON THURSDAY WITH GUSTY SOUTH WINDS WILL BE FOLLOWED BY EVEN GUSTIER NORTHWEST WINDS AND TEMPERATURES SOME 30 DEGREES LOWER THAN THAN ON THURSDAY. IN THE WAKE OF THIS SYSTEM...COOL CANADIAN HIGH PRESSURE WILL SETTLE INTO THE OHIO VALLEY FOR THE WEEKEND WITH THE THREAT OF MORNING FROST AND SOME DRY WEATHER. && .NEAR TERM /UNTIL 6 AM THURSDAY MORNING/... KIND OF A TRICKY NEAR TERM FORECAST. SURFACE ANALYSIS/METARS CLEARLY SHOW A MORE SYNOPTIC SCALE WARM FRONTAL BOUNDARY LIFTING THROUGH THE I-70 CORRIDOR RIGHT NOW WITH COOL 50S AND EASTERLY FLOW OVER NRN OHIO/IND...AND SLY FLOW AND MILD 70S OVER SRN OH/IND. HOWEVER...A PERSISTENT/REMNANT OUTFLOW BOUNDARY CONTINUES TO PERCOLATE WITH CONVECTION IN A NW-SE AXIS FROM BLOOMINGTON IND TO LOUISVILLE AND ON TO THE SOUTHEAST FROM THERE. LOCAL LAPS ANALYSIS SHOWS THAT SURFACE BASED INSTBY HAS LEAKED NORTH OF THE OUTFLOW BOUNDARY INTO THE TRI STATE AREA...WITH MLCAPES AROUND 1000 J/KG. HOWEVER...FLOW ATOP THE OUTFLOW BOUNDARY IS MODESTLY WEAK FOR MID APRIL...AND SHEAR IS MARGINAL FOR ORGANIZED STORM DEVELOPMENT /RIGHT AROUND 30KTS IN THE LOWEST 6KM/ GIVEN THE ALREADY WEAK INSTBY. LATEST /17.12Z 4KM SPC WRF AND 17.15Z EXPERIMENTAL 3KM HRRR/ RUNS HAVE BEEN TRYING TO SUGGEST THAT ISOLD/SCT UPDRAFTS WILL SLOWLY MOVE/DEVELOP NORTHEAST TOWARD THE TRI-STATE...MOVING OFF THE OUTFLOW BOUNDARY BEFORE COLLAPSING SOMEWHERE IN SWRN/WRN OH OR ERN IND. THIS SEEMS PLAUSIBLE GIVEN THE INSTBY THAT HAS LEAKED NORTH OF THE OUTFLOW. BACKGROUND ASCENT IS VERY WEAK...THUS FEEL ANY UPDRAFTS/STORMS WILL BE TIED CLOSELY TO THE DIURNAL INSTBY CYCLE AND LOCALIZED CONVERGENCE NEAR THE OUTFLOW. HAVE ALLOWED FOR A 25-30% PROBABILITY OF STORMS IN THE TRI-STATE FOR THE NEXT 3-4 HOURS BEFORE BACKING OFF INTO LOWER PROBS FURTHER NORTH AS THE NIGHT WEARS ON. NOT OUT OF THE REALM OF POSSIBILITIES THAT BRIEF HAIL WOULD BE POSSIBLE WITH THE STRONGER CORES...AND POCKET OF ELEVATED DCAPE PER SPC MESOA EVEN LENDS SUGGESTION OF A GUSTY STORM OR TWO. CURRENT TRAJECTORY OF NON-SEVERE CORES IMMEDIATELY WEST OF KLMK SUGGESTS THAT OWEN/CARROL COUNTIES IN A FEW HOURS MAY HAVE SOME STRONGER STORMS TO DEAL WITH. && .SHORT TERM /6 AM THURSDAY MORNING THROUGH FRIDAY NIGHT/... FOUND MODEL AGREEMENT TO BE VERY STRONG THROUGH THIS PERIOD AND GOING FORECAST HAD LARGELY CAPTURED THE ENTIRE FCST SCENARIO EXTREMELY WELL...THUS CHANGES WERE REALLY FOCUSED ON DETAILS OF WINDS/TIMING OF STORMS...AND TIGHTENING UP GRADIENTS AHEAD/BEHIND THE EXPECTED COLD FRONT TOMORROW NIGHT. AFTERNOON GOES WATER VAPOR IMAGERY AND RAP ANALYSIS INDICATED A VERY DYNAMIC AND COLD LONGWAVE TROUGH /-30C AT 500MB NEAR SLC AT 12Z/ OVER THE INTERMOUNTAIN WEST WITH SEVERAL IMPRESSIVE CONVECTIVE COMPLEXES DOWNSTREAM NEAR THE ATTENDANT FRONTAL SYSTEMS OVER THE MID MS VALLEY. HEIGHTS HAVE BEEN RISING OVER THE OHIO VALLEY MUCH OF THE DAY BUT THAT PROCESS WILL TURN AROUND AS A STRONG SHORTWAVE TROUGH/UPPER JET DIGS THROUGH THE LONGWAVE TROUGH AND EJECTS INTO THE CENTRAL PLAINS...LOWERING HEIGHTS DOWNSTREAM OVER THE OHIO VALLEY AND ALLOWING A STRONG COLD FRONT AND LOW PRESSURE TO FURTHER ORGANIZE AND PUSH EAST TOWARD THE AREA. POOL OF VERY WARM /+15C AT H85/ AIR JUST TO OUR SOUTHWEST WILL LIFT NORTHWARD AS WARM MENTIONED ABOVE CONTINUES NORTH AND DEEPER SLY FLOW IS ATTAINED. AS DYNAMICS REALLY BEGIN TO INCREASE ON THURSDAY MORNING...LOW LEVEL WIND FIELD AND FALLING PRESSURES TO THE WEST WILL INDUCE A POTENT WARM ADVECTION REGIME...WITH EFFICIENT MIXING UNDER PARTLY CLOUDY SKIES. NAM/GFS SFC PRESSURE GRADIENT MAGNITUDES AND SOUNDING ANALYSIS VALID THURS AFTN SUGGESTS A WINDY DAY...SUSTAINED 20 TO 30 MPH WITH GUSTS TO 40 MPH...ESPECIALLY WEST OF I-71 FROM 10 AM THROUGH THE AFTN. A LITTLE CONCERNED FOR WIND ADVISORY CONDITIONS IN OUR FAR NORTHWEST WHICH IS A WIND PRONE AREA AND WILL BE UNDER THE STRONGEST INFLUENCE OF THE DEVELOPING/DEEPENING SFC-850MB CYCLONE AND ATTENDANT LOW LEVEL JET. WILL CONTINUE TO HIGHLIGHT WIND THREAT ON HWO. MAX TEMPS SHOULD WARM CONSIDERABLY...INTO THE 80S MOST AREAS AND WITH A MORE SELY TRAJECTORY OVER OUR EAST...THIS IS DOWNSLOPE/DRYING OFF THE APPALACHIAN RISE AND MAY ALLOW BETTER DEW POINT REDUCTION/WARMING. LIKELY WILL FALL A FEW DEGREES SHORT OF RECORDS...WHICH ARE IN THE MID/UPPER 80S. GETS VERY INTERESTING THURSDAY AFTER ABOUT 5 PM WHEN STRONG DEEP LAYERED ASCENT AND LOW LEVEL CONVERGENCE IN VICINITY OF FRONTAL ZONE TO THE WEST SHOULD CONTINUE TO FOSTER DEVELOPMENT OF A VERY LONG/STRONG SQUALL LINE. THERE/S BEEN HINTS IN THE HIGHER RES CONVECTION ALLOWING DATA THAT A FEW DISCRETE CELLS MAY FORM IN THE WARM SECTOR OVER OUR FAR WEST LATE AFTN/EARLY EVENING AND THAT WOULD BE PROBLEMATIC GIVEN A WEAK MLCINH FIELD /ERODED CAP/ AND MLCAPE AROUND 1500 J/KG AMIDST VERY STRONG FLOW /SHEAR/. RIGHT NOW AM NOT SEEING A STRONG/CONSISTENT SIGNAL THERE...SO KEEPING RAIN CHANCES LOW THROUGH THE DAY. AS THE EVENING WEARS ON...ADVANCING FRONTAL ZONE /OR PREFRONTAL TROUGH/ WILL BECOME FOCUS FOR CONTINUED ADVANCEMENT AND DEVELOPMENT OF CONVECTIVE SQUALL LINE INTO THE WFO ILN AREA SOMETIME BETWEEN 10 PM AND 2 AM. THINK LATEST SWODY2 FROM SPC IS REALISTIC...THAT WFO ILN WRN CWA WILL BE A TRANSITION AREA FROM A VERY POTENT QLCS WITH SEVERE THREAT...TO A NON-LIGHTNING PRODUCING LINE OF RAIN OR SHOWERS LATE IN THE NIGHT INTO THE EARLY MORNING HOURS ON FRIDAY. CLEARLY THE HIGHEST THREATS LOCALLY OF WIND ARE IN OUR FAR WEST BEFORE CONVECTION ENTRAINS AN INCREASINGLY HOSTILE LOW LEVEL AIRMASS /REF ABOVE COMMENT ABOUT DRYING ON SOUTH-SELY FLOW INTO ERN AREAS/...AND SOUNDING ANALYSIS FROM A MULTITUDE OF NWP SOURCES INDICATES ANY SURFACE BASED/NEAR SURFACE BASED INSTBY WILL BE MINIMAL AT BEST /100 J/KG/ WEST OF I-75. PRIOR NOCTURNAL QLCS EVENTS HOWEVER SUGGEST MLCAPE/MUCAPE IN THESE STRONGLY FORCED EVENTS IS OVERRATED TO A DEGREE...AND GIVEN THE EXPECTED 0-1KM SHEAR TOWARD 50KTS...THE SHAPE/ORIENTATION OF THE LOWEST 1KM TEMP TRACE IS VERY IMPORTANT FOR QLCS COUPLETS AND/OR DAMAGING WIND TRANSPORT TO THE SURFACE. FCST SOUNDINGS ARE HARD TO BUY INTO GIVEN FICKLE NATURE OF BOUNDARY LAYER RESOLUTION IN NWP...BUT ISOTHERMAL TO WEAKLY NEGATIVE LAPSE RATES INDEED SUGGESTS WE MAY VERY WELL HAVE A THREAT FOR DAMAGING GUSTS ESP IN THE FIRST COUPLE OF HOURS OF THE EVENT WEST OF I-75. WITH TIME...BUOYANCY REALLY TANKS AND EXPECT THIS CONVECTIVE SYSTEM TO STRUGGLE TO OR NOT PRODUCE LIGHTNING OVER THE ERN 1/2 OF THE FORECAST AREA LATE IN THE NIGHT AND FRIDAY MORNING. ALSO...WHILE WINDS MAY DECREASE EARLY IN THE EVENING...ISALLOBARIC COMPONENT IMMEDIATELY IN ADVANCE OF THE VERY SHARP/STRONG FRONAL ZONE WILL PROBABLY ALLOW FOR A BRIEF/RAPID INCREASE IN SUSTAINED AND GUSTS IMMEDIATELY AHEAD OF THE SQUALL LINE. FOR FLOOD CONCERN...SYSTEM WILL BE PROGRESSIVE AND HAVE HIGH CONFIDENCE IN RAIN AMOUNTS REMAINING LESS THAN AN INCH IN MOST AREAS. HEAVIEST WEST...LIGHTEST EAST. FEEL ANY FLOODING ISSUES WOULD BE BRIEF/NUISANCE AND TIED TO AREAS OF VERY MOIST SOILS FROM MERCER INTO HARDIN/DELAWARE COUNTIES. FRIDAY TO BE POLAR OPPOSITE OF THURSDAY...A 30 DEGREE TEMP CHANGE /PERHAPS MORE IN THE WEST/ FROM DAYTIME MAX TO DAYTIME MAX...WITH MORE GUSTY WINDS AND A RAPID END TO THE RAIN WITH DRY SLOT. THINK WIND ADVISORY MAY BECOME LIKELY IN NORTH/WEST AT SOME POINT AS SFC CYCLONE REACHES LOWEST PRESSURES /SUB-990MB/ OVER LAKE SUPERIOR. A VERY CHILLY/MISERABLE DAY IN COMPARISON TO THURSDAY. ENOUGH WEAKENING IN THE MSLP GRADIENT FRIDAY NIGHT AND POTENTIAL CLEARING TO WARRANT INSERT OF PATCHY FROST...THOUGH FOLLOWING NIGHT LOOKS EVEN BETTER FOR FROST. && .LONG TERM /SATURDAY THROUGH WEDNESDAY/... A STRONG AREA OF HIGH PRESSURE WILL BUILD IN THE MID SECTION OF THE COUNTRY ON SATURDAY AND NOSE INTO THE GREAT LAKES AND OHIO VALLEY REGION BY EVENING. SOUTHEAST FLOW WILL THEN GRADUALLY TURN SOUTH AHEAD OF THE NEXT COLD FRONT EXPECTED TO MOVE THROUGH LATE IN THE FORECAST PERIOD. MODELS ARE IN A WIDE RANGE FOR TIMING FOR THE TUESDAY/WEDNESDAY SYSTEM. THE PREVIOUS FORECAST APPEARS TO HAVE THE BEST INITIAL CONDITIONS BUT SOME NEIGHBORING OFFICES APPEAR HIGHER THAN I AM WILLING TO GO WITH RAIN CHANCES OVERNIGHT TUESDAY. GIVEN THE LATEST EUROPEAN WHICH SPINS THE SYSTEM UP IN THE MIDWEST ON TUESDAY...IT HAS A MUCH SLOWER AND MORE DEVELOPED SYSTEM THAN THE GFS WHICH IS INDICATING AN OPEN WAVE YET STRONG COLD FRONTAL PASSAGE EARLY WEDNESDAY. WPC HAS THIS FRONT ON THE OTHER SIDE OF THE APPALACHIANS AT THIS TIME WHICH APPEARS INCONSISTENT WITH THE REST OF THE GUIDANCE I SEE. UNTIL THE RAIN HITS WITH THE NEXT SYSTEM DAYS 6/7...TEMPERATURES WILL BE ON THE INCREASE AND START FROM A COOLER 50S ON SATURDAY WITH OVERNIGHT LOWS LIKELY NEEDING FROST HEADLINES. BY THIS TIME NEXT WEEK AHEAD OF THE COLD FRONT...70S WILL BE FOUND AGAIN WITH OVERNIGHT LOWS IN THE 50S. HAVE GONE WARMER THAN GUIDANCE AHEAD OF THE NEXT SYSTEM BUT FEEL THAT THE FORECAST WILL CONTINUE TO BE ADJUSTED UPWARD A LITTLE BIT EACH DAY. && .AVIATION /00Z THURSDAY THROUGH MONDAY/... A WARM FRONT SITUATED ACROSS THE TAF SITES WILL CONTINUE TO PUSH NORTH TONIGHT. WINDS WILL GRADUALLY BECOME MORE SOUTHERLY ACROSS THE TAF SITES. GUIDANCE IS SUGGESTING SOME MVFR FOG AT THE TAF SITES OVERNIGHT HOWEVER BELIEVE WITH WINDS STAYING UP THROUGH THE NIGHT THAT FOG WILL PROBABLY NOT BE AN ISSUE. WINDS WILL REALLY RAMP UP FOR THE DAY ON THURSDAY WITH WIND GUSTS EXCEEDING 30 KNOTS AT TIMES FOR THE LATE MORNING AND THROUGH THE AFTERNOON HOURS. ALTHOUGH A FEW SPOTTY SHOWERS AND THUNDERSTORMS WILL BE POSSIBLE DURING THE DAY ON THURSDAY COVERAGE WILL BE VERY LIMITED AND THEREFORE LEFT OUT OF THE TAFS AT THIS TIME. OUTLOOK...GUSTY SOUTHERLY WINDS WILL CONTINUE THROUGH THURSDAY EVENING. A BRIEF PERIOD OF MVFR CEILINGS AND VISIBILITIES ARE POSSIBLE AS SHOWERS AND THUNDERSTORMS MOVE THROUGH LATE THURSDAY NIGHT AND EARLY FRIDAY MORNING. WEST WINDS GUSTING TO 30 KT LIKELY FRIDAY. && .ILN WATCHES/WARNINGS/ADVISORIES... OH...NONE. KY...NONE. IN...NONE. && $$ SYNOPSIS...BINAU NEAR TERM...BINAU SHORT TERM...BINAU LONG TERM...FRANKS AVIATION...NOVAK
AREA FORECAST DISCUSSION
NWS CLEVELAND OH
849 AM EDT TUE APR 16 2013 .SYNOPSIS... A WEAK COLD FRONT WILL MOVE SOUTH ACROSS THE AREA TODAY AND STALL ACROSS SOUTHERN OHIO TONIGHT. THIS FRONT WILL LIFT NORTH AS A WARM FRONT ON WEDNESDAY NIGHT AHEAD OF A LOW PRESSURE SYSTEM APPROACHING FROM THE PLAINS. THIS SYSTEM WILL TRACK NORTHEAST THROUGH THE GREAT LAKES REGION PULLING A STRONG COLD FRONT EAST ACROSS THE AREA ON FRIDAY. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... UPDATED...MINOR ADJUSTMENT TO POP AND WX GRIDS BASED ON RADAR THIS MORNING AND EXPECTED MOVEMENT THROUGH THE MORNING AND EARLY AFTERNOON. ALSO ADJUSTED HOURLY TEMPS AND AFTERNOON HIGH TEMP USING HRRR GUIDANCE WHICH SHOWS NICELY THE COOL DOWN OFF THE LAKE THIS AFTERNOON AS WINDS TURN ONSHORE. ORIGINAL DISCUSSION...APPROACHING FRONTAL BOUNDARY IS STILL LOCATED ACROSS SE LOWER MICHIGAN EARLY THIS MORNING. CONVECTION HAS BEEN RAPIDLY APPROACHING ACROSS CENTRAL ILLINOIS AND WESTERN INDIANA WHERE DEEP MOISTURE CONVERGENCE IS MAXIMIZED ALONG THE 925-850MB FRONT. WE WILL CONTINUE TO SEE MOISTURE ADVECTION INCREASING ACROSS NRN OHIO WHERE THE LOW LEVEL JET IS FOCUSED WITH CONVERGENCE INCREASING AS THE FRONT SETTLES SOUTH. EXPECTING TO SEE SHOWERS AND THUNDERSTORMS SPREAD EAST ACROSS NRN OHIO...EVEN REACHING NW PA BY LATE THIS MORNING. OVERALL COVERAGE OF SHOWERS WILL DECREASE BY THIS AFTERNOON AS WE LOSE THE LOW LEVEL JET SUPPORT AND MORE STABLE AIR ARRIVES BEHIND THE FRONT. TEMPERATURES WILL FALL AS THE RAIN MOVES IN THIS MORNING AND WILL STRUGGLE TO RECOVER BEHIND THE FRONT THIS AFTERNOON. HIGHS WILL RANGE FROM THE UPPER 50S TO LOW 60S SOUTH. CHALLENGE FOR THIS AFTERNOON WILL BE DETERMINING COVERAGE OF SHOWERS AND THUNDERSTORMS AS THE FRONT SINKS SOUTH WHILE MAIN UPPER LEVEL SUPPORT PASSES WELL NORTH OF THE AREA. MODEL SOUNDING ARE A BIT OVERDONE WITH DEWPOINTS BY THIS AFTERNOON AND THINK WE WILL SEE VALUES ACROSS CENTRAL OHIO PEAK IN THE LOWER 50S WHICH WILL LIMIT SURFACE BASED INSTABILITY. WE WILL HAVE TO KEEP AN EYE ON WHERE THE FRONTAL BOUNDARY SETS UP BUT EXPECTING BEST CHANCES WILL BE ACROSS THE EXTREME SE PORTION OF THE FORECAST AREA FROM MOUNT VERNON TO YOUNGSTOWN ALONG AND BEHIND THE FRONT. A LITTLE HARD TO PINPOINT IF THERE WILL BE ENOUGH SHORTWAVE ENERGY RIDING AROUND THE RIDGE LATE THIS AFTERNOON TO FIRE OFF A SECOND ROUND OF CONVECTION BUT WILL HOLD ONTO CHANCE POPS TO ACCOUNT FOR THIS. SPC KEEP THE SLIGHT RISK FOR SEVERE THUNDERSTORMS JUST TO OUR SOUTH AND AGREE WITH THE LOCATION. && .SHORT TERM /6 PM THIS EVENING THROUGH FRIDAY NIGHT/... UPPER LEVEL RIDGE BUILDS AGAIN OVERNIGHT AS THE WESTERN TROUGH PUSHES EASTWARD. THE NAM HAS BEEN THE MORE ENERGETIC MODEL WITH ISENTROPIC ASCENT INCREASING ACROSS NW OHIO AND TRIES TO SHOW SHOWERS DEVELOPING. THINK THIS IS OVERDONE WITH BETTER LIFT ASSOCIATED WITH THE LLJ FOCUSED BACK TOWARDS IOWA SO WILL ONLY CARRY LOW POPS IN THE WEST OVERNIGHT. THE WARM FRONT LOOKS SLOW TO LIFT BACK NORTH ON WEDNESDAY WITH MOSTLY CLOUDY SKIES IN PLACE ACROSS THE AREA. EAST TO NORTHEAST FLOW OFF THE LAKE WILL KEEP TEMPERATURES AT OR BELOW NORMAL IN THE UPPER 50S TO NEAR 60 DEGREES. WARM FRONT PUSHES BACK NORTH WEDNESDAY NIGHT LEAVING THE FORECAST AREA IN THE WARM SECTOR ON THURSDAY. BREEZY SOUTHERLY WINDS NEAR 20 MPH WITH GUSTS OF 30-35 MPH ARE POSSIBLE WHICH WILL HELP TO PUSH TEMPERATURES NEAR THE 80 DEGREE MARK. THE FRONT WILL BE CLOSE ENOUGH TO NW OHIO TO SEE OCCASIONAL SHOWERS/THUNDERSTORMS AND ENOUGH CLOUDS TO KEEP TEMPERATURES A FEW DEGREES COOLER. OTHERWISE THE FRONT FINALLY SWEEPS EAST ACROSS THE AREA ON FRIDAY BRINGING A RETURN TO MUCH COOLER TEMPERATURES FOR THE WEEKEND. MODELS HAVE BEEN SLOWING DOWN THE TIMING OF THE FRONT BUT CURRENTLY SHOW IT CLEARING MOST OF THE AREA BY MID AFTERNOON ON FRIDAY. ANY FURTHER SLOWING WILL HELP TO INCREASE INSTABILITY AND POTENTIAL FOR STRONGER THUNDERSTORMS ALONG THE FRONT. && .LONG TERM /SATURDAY THROUGH MONDAY/... THE UPPER LEVEL TROUGH SHOULD MOVE EAST OF THE REGION ON SATURDAY. HOWEVER THERE MAY STILL BE SOME LINGERING RAIN OR SNOW SHOWERS ACROSS NW PA THROUGH SATURDAY MORNING. HIGH PRESSURE IS EXPECTED TO TAKE CONTROL BY SATURDAY NIGHT BUT WILL MOVE OFF THE NEW ENGLAND COAST BY MONDAY MORNING. AFTER A COLD DAY WITH HIGHS IN THE 40S ON SATURDAY IT WILL BE WARMER ON SUNDAY...BUT STILL BELOW SEASONAL AVERAGES. AS SOUTHERLY WINDS RETURN ON MONDAY HIGHS WILL RETURN TO WITHIN A COUPLE DEGREES OF 60. && .AVIATION /13Z TUESDAY THROUGH SATURDAY/... OUTFLOW FROM SHOWERS AND THUNDERSTORMS ACROSS NW OHIO ARE HELPING MOVE A COLD FRONT INTO THE CENTRAL PORTION OF NORTHERN OHIO. THERE HAS BEEN SOME MVFR CONDITIONS WITH LOCALIZED IFR IN THE HEAVIEST THUNDERSTORMS. THE BETTER CHANCES OF SEEING THUNDER THIS MORNING WILL BE GENERALLY ALONG AND NORTH OF A KFDY TO KCLE TO KERI LINE. MOST OF THE MORNING THUNDERSTORMS SHOULD WEAKEN AS THEY LIFT TO THE NORTHEAST. AWAY FROM THESE MORNING SHOWERS AND THUNDERSTORMS MOST LOCATIONS WILL BE VFR. UNCERTAINTY FOR THE AFTERNOON IS HOW MUCH SHOWER AND THUNDERSTORM ACTIVITY WILL DEVELOP ALONG THE FRONTAL BOUNDARY THAT SHOULD BE NEAR A KJHW TO KI43 LINE AROUND 20Z. BELIEVE THE THUNDER CHANCES ARE HIGH ENOUGH TO MENTION AT KCAK AND KYNG FOR THE MID TO LATE AFTERNOON. THE SHOWERS AND THUNDERSTORMS THAT CAN DEVELOP WILL PRODUCE MVFR CONDITIONS. AWAY FROM THE SHOWERS CEILINGS SHOULD BE VFR. WINDS WILL REMAIN GUSTY AHEAD OF THE FRONT FROM A SOUTHERLY DIRECTION BUT WILL SHIFT AROUND TO THE WEST AND NORTHWEST THROUGH THE AFTERNOON. WINDS WILL EVENTUALLY MAKE IT AROUND TO THE NORTHEAST DURING THE EVENING. .OUTLOOK...NON VFR AT TIMES IN SHOWERS AND THUNDERSTORMS TUESDAY NIGHT INTO WEDNESDAY AND AGAIN ON FRIDAY. && .MARINE... SOUTHERLY WINDS WILL BE STRONGEST THIS MORNING ALONG THE PA SHORELINE. BELIEVE WE WILL REMAIN JUST UNDER SMALL CRAFT CONDITIONS. WINDS WILL SHIFT LATE THIS MORNING TO EARLY AFTERNOON AS A COLD FRONT MOVES ACROSS THE LAKE. THIS FRONT WILL STALL NEAR THE OHIO RIVER VALLEY THEN MOVE BACK TO THE NORTH AS A WARM FRONT. THE WARM FRONT WILL LIFT NORTH OF LAKE ERIE WEDNESDAY WITH SOUTHERLY WINDS RETURNING. SOUTHERLY WINDS MAY END UP BEING STRONG ENOUGH AHEAD OF ANOTHER COLD FRONT ON FRIDAY TO CAUSE SMALL CRAFT ADVISORY CONDITIONS. COLD ADVECTION IN THE WAKE OF THIS FRONT WILL BE STRONG ENOUGH TO INCREASE SOUTHWESTERLY WINDS TO 30 KNOTS. WE WILL NEED TO MONITOR FOR THE POTENTIAL OF GALE CONDITIONS FOR A FEW HOURS FRIDAY NIGHT INTO EARLY SATURDAY. HIGH PRESSURE WILL TAKE CONTROL BY SATURDAY NIGHT WITH CALMER CONDITIONS EXPECTED. && .CLE WATCHES/WARNINGS/ADVISORIES... OH...NONE. PA...NONE. MARINE...NONE. && $$ SYNOPSIS...KEC NEAR TERM...KEC/TK SHORT TERM...KEC LONG TERM...MULLEN AVIATION...MULLEN MARINE...MULLEN
AREA FORECAST DISCUSSION
NWS SIOUX FALLS SD
848 PM CDT WED APR 17 2013 .UPDATE... ISSUED AT 845 PM CDT WED APR 17 2013 FIRST WAVE EXITING CWA THIS EVENING WITH A LULL IN THE PRECIPITATION. HRRR IS HANDLING THIS FEATURE QUITE WELL WITH SECONDARY WAVE LIFTING NORTHEAST INTO CWA AFTER 06Z TONIGHT. MORE CONVECTION IS FIRING UP ACROSS KANSAS WITH THIS FEATURE WHICH AGAIN FORECAST FAIRLY WELL BY HRRR. SO WILL HAVE LOWERED POPS THE REST OF THE EVENING WITH AN INCREASE IN POPS AGAIN LATER TONIGHT. NO CHANGE IN HIGHLIGHTS EXPECTED. && .SHORT TERM...(THIS EVENING THROUGH THURSDAY) ISSUED AT 314 PM CDT WED APR 17 2013 IN THE SHORT RANGE...FORECAST AREA IS BETWEEN WAVE SEGMENTS...WITH THE WARM AIR ADVECTION FROM THIS MORNING GONE...AND THE MAIN PORTION OF THE UPPER TROUGH/WAVE ENERGY STILL TO THE SOUTH. CURRENTLY...NEXT ROUND OF CONVECTION IS NOW FIRING UP IN CENTRAL KANSAS...WHICH MAY SCRAPE ALONG OUR SOUTHEAST ZONES THIS EVENING. THEREFORE KEPT THE MENTION OF RAIN WITH EMBEDDED THUNDER IN THOSE AREAS THIS EVENING. BUT ELSEWHERE...DRY MID LEVELS WILL INHIBIT BONAFIDE PRECIPITATION FROM FALLING. RELIED HEAVILY ON THE WARMEST MODEL ALOFT I COULD FIND...WITH WAS THE NAM FOR PRECIPITATION TYPE. BUT OVERALL FOR THIS EVENING OUTSIDE OF NORTHWEST IOWA...JUST WENT OCCASIONAL LIGHT PRECIPITATION WITH THE TYPE DEPENDING ON WHAT THE SURFACE TEMPERATURES AND THE WARM AIR BUBBLE ALOFT WERE DOING. LATER TONIGHT...THE MAIN PORTION OF THE WAVE BEGINS TO ENCROACH INTO OUR AREA THEREFORE EXPECTING THE MID LEVELS TO SATURATE. THEN ON THURSDAY...PV ADVECTION IS VERY STRONG AS THE WAVE STRONGLY INFLUENCES THIS REGION. THE UPPER QG FORCING MOVES RIGHT OVER THE HEART OF OUR FORECAST AREA...AND MID LEVEL INSTABILITY IS EVIDENT. LASTLY...A DECENT TROWAL EXISTS AT THE 305K LEVEL INTO OUR FORECAST AREA BACKING INTO SW MN...EAST CENTRAL SD AND SOUTHEAST SD. WITH ALL THIS SAID...THERE COULD VERY WELL BE A HEAVY BAND OF SNOW SETTING UP LATE TONIGHT AND THURSDAY IN THESE LOCATIONS AND IMMEDIATE ADJACENT AREAS FOR 6 TO 9 INCHES OF SNOW...COUPLED WITH A LOT OF WIND OF 25 TO 35 MPH...AND SOME GUSTS UP TO 40 MPH. THEREFORE DECIDED TO ISSUE A WINTER STORM WARNING FOR THOSE AREAS. ELSEWHERE...DECIDED TO ISSUE AN ADVISORY FOR LATE TONIGHT THROUGH THURSDAY EVENING EXTENDING EASTWARD INCLUDING A LINE FROM SIOUX CITY...TO SPENCER IOWA AND JACKSON MN...FOR THE POTENTIAL OF SOME LIGHT ICING LATE TONIGHT FOLLOWED BY 2 TO 4 INCHES OF SNOW AND THE WIND. THE CURRENT WINTER WEATHER ADVISORY IN OUR WESTERN ZONES STILL LOOKED GOOD...AS LESS POTENTIAL FOR HEAVY SNOW EXISTS IN THOSE ZONES. .LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY) ISSUED AT 314 PM CDT WED APR 17 2013 RELATIVELY GOOD MODEL AGREEMENT IN THE NEAR TERM WITH TROWAL WORKING THROUGH THE AREA THURSDAY NIGHT. HAVE INCREASED POPS WITH THIS FEATURE...ESPECIALLY EAST OF THE JAMES RIVER VALLEY. SYSTEM PULLS OUT OF THE AREA ON FRIDAY..HOWEVER...BRISK NORTHWEST WINDS CONTINUE THROUGHOUT THE DAY. MODELS INDICATE RELATIVELY POOR MIXING WITH MID CLOUD AND FRESH SNOW COVER ACROSS THE AREA...SO GUSTS MAY NOT BE AS BAD AS THEY WOULD BE WITHOUT THESE FEATURES. APPEARS AS THOUGH SKIES WILL CLEAR FRIDAY NIGHT...AND WITH WINDS DROPPING OFF SHOULD SEE GREAT RADIATIVE CONDITIONS. MID LEVEL CLOUDS WILL BE ON THE INCREASE ACROSS CENTRAL SOUTH DAKOTA AFTER MIDNIGHT IN ADVANCE OF THE NEXT SERIES OF WAVES APPROACHING THE AREA. AS A RESULT...HAVE COOLEST TEMPERATURES FORECAST FROM I-29 AND EAST ALONG THE HIGHWAY 14 CORRIDOR. DIRTY ZONAL FLOW DOMINATES ACROSS THE REGION THROUGH THE WEEKEND INTO EARLY NEXT WEEK. HAVE THE CHANCE OF SHOWERS WITH THESE DISTURBANCES MOVING THROUGH...HOWEVER...AS A SURFACE COLD FRONT MOVES SOUTH THROUGH THE AREA SUNDAY NIGHT INTO MONDAY LOWER LEVELS COOL OFF ENOUGH THAT PREVAILING PRECIPITATION TYPE COULD SWITCH AND CHANGE OVER TO SNOW. MODELS DISSENSION INCREASES TOWARDS THE MIDDLE OF NEXT WEEK AS ECMWF SUGGESTS A DEEPENING TROUGH ON THE BACK EDGE OF THE SHORT WAVE TRAIN...WHILE THE GFS ADVERTISES MORE OF A FULL LATITUDINAL TROUGH. WITH UNCERTAINTY WITH THE SYSTEM...LEFT MID-RANGE POPS IN THROUGH TUESDAY. && .AVIATION...(FOR THE 00Z TAFS THROUGH 00Z THURSDAY EVENING) ISSUED AT 629 PM CDT WED APR 17 2013 DETERIORATING CONDITIONS THROUGH THE NIGHT AS MIXED PRECIPITATION OVERSPREADS THE AREA. MAY HAVE SOME ISOLATED THUNDERSTORM ACTIVITY OVER NORTHWESTERN IOWA EARLY IN THE EVENING...OTHERWISE PRECIPITATION THAT DEVELOPS WILL BE MAINLY IN THE FORM OF SNOW THROUGH THE JAMES RIVER VALLEY...WITH A BAND OF MIXED PRECIPITATION EAST OF THIS AREA...THEN ALL RAIN THROUGH NORTHWESTERN IOWA. AS THE NIGHT PROGRESSES...PRECIPITATION WILL TRANSITION TO ALL SNOW FROM WEST TO EAST...WITH SNOW THEN PERSISTING INTO THURSDAY EVENING. IN ADDITION...NORTHWESTERLY WINDS WILL INCREASE TONIGHT AND TOMORROW...WITH GUSTS OF 35 TO 40 KTS ON THURSDAY AFTERNOON. && .FSD WATCHES/WARNINGS/ADVISORIES... SD...WINTER WEATHER ADVISORY FROM 1 AM THURSDAY TO 1 AM CDT FRIDAY FOR SDZ070-071. WINTER STORM WARNING UNTIL 1 AM CDT FRIDAY FOR SDZ039-040-054- 055-060-061-065-068. WINTER WEATHER ADVISORY UNTIL 1 AM CDT FRIDAY FOR SDZ038-050-052- 053-057>059-063-064. WINTER STORM WARNING FROM 1 AM THURSDAY TO 1 AM CDT FRIDAY FOR SDZ056-062-066-067-069. MN...WINTER WEATHER ADVISORY FROM 1 AM THURSDAY TO 1 AM CDT FRIDAY FOR MNZ090. WINTER STORM WARNING FROM 1 AM THURSDAY TO 1 AM CDT FRIDAY FOR MNZ071-072-080-081-089-097-098. IA...WINTER WEATHER ADVISORY FROM 1 AM THURSDAY TO 1 AM CDT FRIDAY FOR IAZ002-012-020. WINTER STORM WARNING FROM 1 AM THURSDAY TO 1 AM CDT FRIDAY FOR IAZ001. WINTER WEATHER ADVISORY FROM 4 AM THURSDAY TO 1 AM CDT FRIDAY FOR IAZ003-013-014-021-031. NE...WINTER WEATHER ADVISORY FROM 1 AM THURSDAY TO 1 AM CDT FRIDAY FOR NEZ013. WINTER WEATHER ADVISORY FROM 4 AM THURSDAY TO 1 AM CDT FRIDAY FOR NEZ014. && $$ UPDATE... SHORT TERM...MJF LONG TERM... AVIATION...JM
AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NWS RAPID CITY SD
509 PM MDT WED APR 17 2013 .UPDATE... ISSUED AT 502 PM MDT WED APR 17 2013 LATEST WATER VAPOUR LOOP AND 21Z RAP GUIDANCE SHOW NEXT WAVE OVER NM...HEADING SWIFTLY TO THE NORTHEAST ON NOSE OF 130KT JET. LIFT ON NOSE OF THIS JET STREAK AND EXITING JET STREAK OVER THE UPPER MIDWEST WILL COMBINE TO BRING INCREASING AREAS OF -SN OVER NE PER KLNX RADAR...WHICH WILL HEAD INTO SOUTH CENTRAL SD TONIGHT. EXPECT MAIN ACCUMULATING SNOWS TO BE OVER THESE AREAS OVERNIGHT. FURTHER WEST -SN WILL LINGER...BUT ACCUMULATIONS WILL BE LIGHT. WILL THUS SHAVE OFF ALL HEADLINES SAVE FOR SOUTH CENTRAL SD WHERE SEVERAL MORE INCHES OF SNOW ARE EXPECTED OVERNIGHT. && .SHORT TERM...THIS EVENING THROUGH THURSDAY NIGHT ISSUED AT 238 PM MDT WED APR 17 2013 CURRENT SURFACE ANALYSIS PLACES LOW OVER NORTHERN NEW MEXICO WITH HIGH SETTLING INTO THE NORTHERN ROCKIES. UPPER LEVEL ANALYSIS PLACES DEEP TROF OVER THE WRN INTO THE CTRL CONUS WITH AXIS STRETCHING FROM ERN SASKATCHEWAN SOUTHWARD TOWARDS THE FOUR CORNERS REGION...WITH BASE CLOSING OFF NEAR WRN COLORADO. VARIETY OF WAVES CONTINUE TO PUSH UP ALONG THE FRONT OF THE WAVE. MAIN AREA OF SNOW OVER PTNS OF SW INTO S CTRL SD ORIENTATED ALONG AXIS OF INCREASING 700 MB FRONTOGENESIS...WHILE OTHER SMALLER BANDS CONTINUE OVER THE CWA. FOR TONIGHT...UPPER TROF CONTINUES ITS SLOW PUSH TO THE EAST WITH SNOW SLOWLY TAPERING FROM WEST TO EAST THROUGH THE OVERNIGHT OVER NERN WYO INTO WRN SD. OVER S CTRL SD...PRIMARY BAND OF SNOW SHIFTS OVER THE AREA THIS EVENING. LATE TONIGHT PRIMARY WAVE WRAPPING AROUND CLOSED LOW EJECTING INTO THE PLAINS WILL PASS MAINLY TO THE EAST...THOUGH ENOUGH LIFT WITH THIS SHOULD KEEP SNOWFALL GOING INTO THE MORNING HOURS. ON THURSDAY...SOME SNOW WILL LINGER INTO THE MORNING HOURS OVER S CTRL SD BEFORE SLOWLY ENDING INTO THE AFTERNOON AS UPPER LOW SLOWLY WORKS ITS WAY TO THE EAST. OVER REMAINDER OF THE CWA...DRY CONDITIONS ARE EXPECTED AS RIDGING QUICKLY BUILDS IN. SFC LOW EJECTS THRU THE MIDWEST AND DEEPENS BRINGING INCREASING NRNLY WINDS TO THE ERN CWA...WHICH MAY LEAD TO SOME BLOWING SNOW. && .LONG TERM...FRIDAY THROUGH WEDNESDAY ISSUED AT 238 PM MDT WED APR 17 2013 MOSTLY DRY CONDITIONS ARE EXPECTED FRIDAY AS A SHORT WAVE RIDGE CROSSES THE NORTHERN PLAINS. AN UPPER TROF WILL SET UP ACROSS THE NORTHERN PLAINS FOR THE WEEKEND INTO EARLY NEXT WEEK. THIS WILL BRING PERIODIC CHANCES FOR RAIN/SNOW ALONG WITH TEMPERATURES REMAINING BELOW AVERAGE. AN UPPER LEVEL RIDGE WILL START TO MOVE INTO THE NORTHERN PLAINS AROUND MIDWEEK...BRINGING DRY CONDITIONS AND MORE SEASONABLE TEMPERATURES. && .AVIATION...(FOR THE 00Z TAFS THROUGH 00Z THURSDAY EVENING) ISSUED AT 502 PM MDT WED APR 17 2013 WIDESPREAD IFR/MVFR CONDITIONS DUE TO LOW CLOUDS/-SN EXPECTED TONIGHT INTO EARLY THURSDAY MORNING ACROSS MUCH WESTERN SD. CONDITIONS WILL BEGIN TO SLOWLY IMPROVE ACROSS NORTHEAST WYOMING LATER THIS EVENING AND OVERNIGHT AS SNOW TAPERS OFF AND CEILINGS RISE TO MVFR LEVELS. CONDITIONS WILL THEN IMPROVE THURSDAY AS STORM SYSTEM MOVES TO THE EAST. && .UNR WATCHES/WARNINGS/ADVISORIES... SD...WINTER WEATHER ADVISORY UNTIL 6 AM MDT THURSDAY FOR SDZ043-044. WINTER WEATHER ADVISORY UNTIL NOON CDT THURSDAY FOR SDZ046-047- 049. WY...NONE. && $$ UPDATE...HELGESON SHORT TERM...77 LONG TERM...15 AVIATION...HELGESON
AREA FORECAST DISCUSSION
NWS SAN ANGELO TX
340 PM CDT TUE APR 16 2013 .SHORT TERM... FRONTAL BOUNDARY HAS SAGGED SOUTH THROUGH THE INTERSTATE 20 CORRIDOR THIS AFTERNOON...WITH NORTH WINDS AT SWEETWATER AND BRIEFLY AT ABILENE. LOOKS LIKE THE FRONT HAS PULLED UP STATIONARY OR MAYBE DRIFTING WEST...WITH MODELS SUGGESTING A RETREAT NORTHWARD AS A WARM FRONT THIS EVENING. HOW FAR NORTH IT RETREATS IS A HUGE QUESTION...WITH THE GFS SHOWING A RAPID RETREAT AND THE RUC MUCH SLOWER. AT THIS POINT...WITH THE GFS HAVING LARGELY MISSED HOW FAR SOUTH THE FRONT WOULD MAKE IT TODAY...AND WITH TEMPERATURES IN THE 50S AND STILL GOOD NORTHEAST FLOW ACROSS OKLAHOMA...WILL LEAN TOWARDS A SOMEWHAT SLOWER RETREAT. VISIBLE SATELLITE SHOWING A LITTLE CU TRYING TO GO ALONG AND JUST NORTH OF THE FRONT ACROSS THE BIG COUNTRY. CAP IS STILL STRONG...BUT AT LEAST A FEW STORMS LOOK VERY POSSIBLE...AS THE CAP WEAKENS LOCALLY AND AS A WEAK UPPER LEVEL SHORTWAVE APPROACHES. EXPECT A FEW ISOLATED STORMS TO DEVELOP SOMEWHERE CLOSE TO ABILENE OR SWEETWATER LATE THIS AFTERNOON AND CONTINUE INTO THE MID EVENING HOURS. NEAR RECORD HIGH TEMPERATURES HERE IN SAN ANGELO...ALONG WITH DEWPOINTS AROUND 60...ARE LEADING TO A VERY UNSTABLE AIR MASS. GIVEN CAPE VALUES IN EXCESS OF 2500 J/KG...IF A STORM CAN DEVELOP...EXPECT IT TO TRY TO REACH SEVERE LEVELS PRETTY QUICK. EXPECT FRONT TO DRIFT NORTH THROUGH THE EVENING...PROBABLY BACK INTO THE NORTHERN BIG COUNTRY BY LATE THIS EVENING...AND BACK OUT OF WEST CENTRAL TEXAS BY SUNRISE. MILD AGAIN SOUTH OF THE BOUNDARY...WITH READINGS HAVING A HARD TIME DROPPING BELOW 70. A LITTLE COOLER ACROSS THE NORTHERN BIG COUNTRY...ALTHOUGH TEMPERATURES THERE MAY EVEN CLIMB SLIGHTLY BY MORNING. MAIN UPPER TROUGH MOVING INTO THE ROCKIES WEDNESDAY AFTERNOON. BEST LIFT WAITS UNTIL WEDNESDAY NIGHT...BUT IT WILL AID THE DRYLINE IN STRENGTHENING AND MOVING EAST. BY AFTERNOON...DRYLINE WILL LIKELY BE SOMEWHERE ACROSS THE WESTERN BIG COUNTRY AND CONCHO VALLEY. CAP WILL STILL BE STRONG...BUT SHOULD BEGIN TO ERODE BY LATE IN THE AFTERNOON. WILL CONTINUE THE SLIGHT CHANCE POPS DURING THE AFTERNOON...WITH ODDS INCREASING QUITE A BIT AFTER DARK. 07 .LONG TERM... CURRENT WEATHER...WV IMAGERY IS SHOWING A TROF AMPLIFYING ACROSS THE WESTERN US. THIS AFTERNOON...STATIONARY FRONT EXTENDS ACROSS EXTREME SOUTHEAST OKLAHOMA...NORTHWEST TEXAS AND THE NORTHERN PERMIAN BASIN. ALSO...MODIFIED ARCTIC HIGH PRESSURE SURFACE RIDGE WAS OVER MONTANA AND THE NORTHERN PLAINS. WEDNESDAY NIGHT...HOW ARE THESE TWO FEATURES GOING TO AFFECT WEST CENTRAL TEXAS WITH POSSIBLE SEVERE WEATHER. THE ALOFT PART IS PRETTY STRAIGHT FORWARD...WITH TROF INTENSIFYING AND MOVING EAST PUTTING THE SOUTHERN PLAINS IN STRONG SOUTHWEST FLOW. ALSO...THE GFS MODEL INDICATING GOOD POLAR AND SUBTROPICAL JET DIVERGENCE AT POSSIBLE PRIME SEVERE WEATHER TIME/WEDNESDAY AFTERNOON AND NIGHT/. THE SURFACE PART IS MORE COMPLEX. THE ECMWF AND NAM MODELS ARE KEEPING THE FRONT FURTHER SOUTH FROM ALONG AN OKLAHOMA CITY TO TULIA LINE THROUGH WEDNESDAY. THE GFS IS MUCH FURTHER NORTH ALONG A GUYMON TO KANSAS CITY LINE. THE GFS MAY BE STRUGGLING DUE PARTLY TO THE WARM EQUATION NUMBERS BEING INPUTED ON APRIL 1ST. GOING MORE WITH THE NAM AND ECMWF DUE TO ARCTIC AIR ALREADY IN PLACE TO OUR NORTH AND A NEGATIVE NAO PATTERN STILL OVER THE EASTERN US. HOWEVER...GOOD SURFACE CYCLOGENESIS IS A GOOD BET WEDNESDAY OVER THE SOUTHERN PLAINS DUE TO STRONG DYNAMICS JUST UPSTREAM. THERE ARE A FEW MORE TWISTS AND TURNS IN THIS FORECAST. STAY TUNED. THE BEST CHANCE OF MORE WIDESPREAD/POSSIBLY SIGNIFICANT/SEVERE WEATHER WILL BE WEDNESDAY AND WEDNESDAY NIGHT ACROSS THE SOUTHERN PLAINS. THE DAY2 OUTLOOK BY SPC OF A MODERATE RISK OVER OKLAHOMA AND EXTREME NORTHWEST TEXAS LOOKS GOOD. THE WARM SECTOR WILL BE PRIMED AHEAD OF THE DRYLINE AND SOUTH OF STATIONARY FRONT. DEWPOINTS WILL BE IN THE MID TO UPPER 60S ALONG WITH STRONG INSTABILITY/MLCAPES OF 2000 TO 3000 J/KG/. WITH THE ADDITION OF STRONG SHEAR...SUPERCELLS ARE A GOOD BET MAINLY DURING THE LATE AFTERNOON AND EARLY EVENING. AT LEAST FOR NOW...THE FRONT WILL MOVE NORTH TO THE I-40 CORRIDOR BY 00Z THU. SO MORE ORGANIZED SEVERE CONVECTION IS MORE LIKELY ACROSS THE BIG COUNTRY LATE WEDNESDAY AFTERNOON AND EVENING. ALSO...THE TEXAS TECH 3KM WRF IS INDICATING A LINE OF CONVECTION FROM ABILENE TO SAN ANGELO JUST AFTER MIDNIGHT. THE MAIN HAZARDS WILL BE LARGE HAIL AND DAMAGING WINDS...ALONG WITH ISOLATED TORNADOES POSSIBLE. GOING WITH LKLY POPS ACROSS THE FAR EASTERN COUNTIES AND MAINLY CHC ELSEWHERE FOR WEDNESDAY NIGHT. THURSDAY THROUGH TUESDAY...COOLER FOR THURSDAY AND FRIDAY WITH HIGHS MAINLY IN THE 60S. A WARMING TREND BY THIS WEEKEND WITH HIGHS IN THE UPPER 70S TO LOWER 80S. THE COLDEST MORNING WILL BE FRIDAY WITH LOWS IN THE 30S. IF SKIES ARE CLEAR AND WINDS CALM...THEN TEMPS MAY DROP TO NEAR FREEZING...ESPECIALLY IN LOW LYING AREAS AND RIVER VALLEYS. 21 && .PRELIMINARY POINT TEMPS/POPS... ABILENE 68 86 56 62 36 / 20 20 40 10 5 SAN ANGELO 70 91 58 65 38 / 10 20 30 10 5 JUNCTION 70 89 63 70 39 / 5 20 50 10 5 && .SJT WATCHES/WARNINGS/ADVISORIES... NONE. && $$
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AREA FORECAST DISCUSSION
NWS MILWAUKEE/SULLIVAN WI
908 PM CDT WED APR 17 2013 .UPDATE... THE HRRR HAS BEEN TRENDING TOWARD PUSHING THE SURFACE BOUNDARY SOUTH WITH THE HEAVIEST RAINS LATER TONIGHT STAYING A LITTLE MORE SOUTH ACROSS NORTHERN ILLINOIS...ALTHOUGH SOME MODERATE TO HEAVY RAIN DOES GET INTO SOUTHERN WISCONSIN. THE NEW NAM IS PUSHING THE HEAVY RAIN ACROSS SOUTHERN WISCONSIN. LATEST SATELLITE/RADAR TRENDS FAVOR THE HRRR. HOWEVER THE STRONG 850 MB JET DOES PUSH INTO FAR SOUTHEAST WISCONSIN DURING THE EARLY MORNING HOURS...SO THE HEAVIER NAM PRECIPITATION CANNOT BE RULED OUT. WITH RIVERS ALREADY NEAR AND OVER FLOOD...THE ADDED WATER IS STILL EXPECTED TO MAKE MANY RIVERS REACH MAJOR FLOOD. && .AVIATION/06Z TAFS/... IFR/LIFR CEILINGS WITH SOME IFR VSBYS WILL CONTINUE INTO THE EARLY MORNING HOURS WITH A FRONTAL BOUNDARY ACROSS CENTRAL ILLINOIS. THIS FRONT SHOULD LIFT NORTH AS A WARM FRONT...AS THE SURFACE LOW REACHES SOUTHEAST WISCONSIN THURSDAY AFTERNOON. STILL EXPECT IFR CONDITIONS WITH SOME LIFT...ESPECIALLY IN THE VICINITY OF THE THE SURFACE LOW. SOME THUNDERSTORMS ALSO EXPECTED. LOW LEVEL WIND SHEAR EXPECTED DURING THE EARLY MORNING HOURS AS THE SOUTH LOW LEVEL JET MOVES INTO SOUTHEAST WISCONSIN WITH THE EAST WINDS AT THE SURFACE. && .PREV DISCUSSION... /ISSUED 335 PM CDT WED APR 17 2013/ TONIGHT AND THURSDAY...FORECAST CONFIDENCE IS MEDIUM TO HIGH. CURRENT AREA OF RAIN AND THUNDER MOVING OUT OF THE AREA FROM WEST TO EAST. WAKE LOW WIND GUSTS OUT OF THE EAST BETWEEN 30 AND 45 MPH ARE EXPECTED FOR AN HOUR OR TWO AFTER THE RAIN ENDS. SEE SPECIAL WEATHER STATEMENT FOR MORE INFORMATION. BRIEF LULL IN ACTIVITY BEFORE NEXT ROUND OF RAIN AND THUNDERSTORMS MOVES IN DURING THE EVENING...THEN PERSISTS LATER TONIGHT INTO THURSDAY. SHORT TERM MODELS IN PRETTY GOOD AGREEMENT WITH TAKING SURFACE LOW NORTHEAST INTO FAR SOUTHEAST IOWA BY 12Z THURSDAY...THEN INTO SOUTHERN WISCONSIN BY 00Z FRIDAY. MODELS DIFFERING A BIT WITH THE EXACT LOCATION OF THE LOW. STRONG UPWARD VERTICAL MOTION MOVES INTO THE AREA TONIGHT...WITH STRONG LOW LEVEL JET NOSE POINTING INTO THE AREA. LOW LEVEL FRONTOGENESIS RESPONSE IS ALSO QUITE STRONG...INTERACTING WITH COPIOUS AMOUNTS OF MOISTURE. PRECIPITABLE WATER VALUES ON AREA FORECAST SOUNDINGS ARE UP TO 1.50 INCHES...WHICH IS NEARLY OFF THE CHARTS FOR MID APRIL. THIS WILL LEAD TO ROUNDS OF THUNDERSTORMS WITH HEAVY RAINFALL MOVING THROUGH THE AREA BY LATER THIS EVENING AND INTO THURSDAY MORNING. RISK OF FLASH FLOODING IS THERE WITH ANY TRAINING CONVECTION AND SATURATED GROUND. ELEVATED CAPES WILL INCREASE THROUGH THE NIGHT...WHICH MAY LEAD TO HAIL OCCURRING WITH ANY STRONGER STORMS. KEPT HEAVY RAINFALL GOING THROUGH THURSDAY AS SURFACE LOW AND WARM SECTOR AIRMASS MOVES INTO THE AREA...AS HIGH PRECIPITABLE WATER VALUES REMAIN. EXPECT ANOTHER 1.50 TO 3.50 INCHES OF RAIN ON TOP OF WHAT HAS ALREADY FALLEN. SHOULD SEE SCATTERED THUNDERSTORMS DEVELOP WITH SURFACE LOW AND COLD FRONT MOVING THROUGH THE AREA. SPC HAS AREA IN SLIGHT RISK FOR SEVERE...WHICH LOOKS GOOD GIVEN DECENT SURFACE BASED CAPES AND STRONG LOW AND DEEP LAYER SHEAR. DAMAGING WINDS AND LARGE HAIL WOULD BE THE MAIN HAZARDS...THOUGH COULD NOT RULE OUT AN ISOLATED TORNADO GIVEN PASSING LOW AND STRENGTH OF LOW LEVEL SHEAR. INSTABILITY SOMEWHAT IN QUESTION WITH CLOUDS AND PRECIPITATION IN THE AREA. KEEP UP WITH THE LATEST FORECASTS. THURSDAY NIGHT...FORECAST CONFIDENCE MEDIUM TO HIGH. TIMING IS KEY HERE IN THE EARLY HOURS. THE STRONG COLD FRONT WILL SWEEP EAST OF THE AREA RIGHT AROUND 00Z...GIVE OR TAKE AN HOUR OR TWO. THE BAND OF HEAVY RAIN SHOULD HEAD OUT WITH IT. TEMPS WILL THEN CRASH THROUGH THE NIGHT WITH THE SECONDARY COLD FRONT SWEEPING IN TOWARD 12Z. BETWEEN THESE TWO FRONTS...THE PRECIP MAY BE NEARLY NON-EXISTENT. SO HIGH POPS IN THE EAST EARLY...A BREAK INTO THE EARLY MORNING...THEN MORE LIGHT PRECIP ARRIVES LATE AS THE SECONDARY FRONT COMES THROUGH...ALONG WITH A LAGGING VERY STRONG UPPER LEVEL TROF. EXPECT A SLOW TRANSITION FROM LIQUID TO SNOW...MAINLY ACROSS SOUTH CENTRAL AREAS. BUT BY THE TIME TEMPS TURN COLD ENOUGH FOR ALL SNOW...THE EXPECT PRECIP AMOUNTS WILL BE LIGHT. SO A DUSTING OF ACCUM IS ALL THAT/S EXPECTED. FRIDAY...FORECAST CONFIDENCE IS HIGH. MAIN ISSUE FOR FRIDAY WILL BE THE WINDS. BEHIND SECONDARY COLD FRONT...LOW LEVEL LAPSE RATES GET QUITE STEEP AND TAP INTO SOME BRISK WINDS. SHOULD BE A 20 TO 30 MPH BLOW WITH SOME HIGHER GUSTS. A CHILLY DAY WITH HIGHS IN THE UPPER 30S TO LOWER 40S. SATURDAY AND SUNDAY...FORECAST CONFIDENCE IS MEDIUM. GENERALLY A QUIET WEEKEND...THOUGH WE COULD SEE SOME RAIN MOVE IN LATER ON SUNDAY WITH THE APPROACH OF THE NEXT TROUGH OF LOW PRESSURE. TEMPS MODIFY EACH DAY AS THE FLOW BACKS TO THE SOUTH AHEAD OF THE TROF. MONDAY INTO WEDNESDAY...FORECAST CONFIDENCE IS LOW TO MEDIUM. THIS LOOKS UNSETTLED AGAIN WITH A SLOW MOVING TROF POTENTIALLY BRINGING A FEW ROUNDS OF RAIN DURING THE PERIOD. THE MODELS AGREE ON THE OVERALL TREND FOR EARLY NEXT WEEK...BUT DIFFER ON SPECIFICS. AVIATION/00Z TAFS/... A WAKE LOW SITUATION HAS DEVELOPED BEHIND THE BACKSIDE OF SHOWERS AND THUNDERSTORMS. WAKE LOW PARAMETERS AND ESTIMATE MAX GUSTS SHOW A STRONG SIGNAL AND COINCIDE WELL WITH LOCATION OF SFC OBS REPORTING GUSTS...THOUGH GUST MAGNITUDES TOO HIGH. THUS...2-HR TEMPO ADDED THOUGH UNCERTAINTY EXISTS WITH TIMING FOR GUSTY WINDS ON THE BACK EDGE OF PRECIP SHIELD WITH GUSTS UP TO 30-45 MPH. BACK EDGE OF PRECIPITATION SHIELD IS APPARENT ON THE RADAR MOSAIC SHOWS...ENDING OF PRECIP AT UES...MKE...ENW...BETWEEN 330 AND 430 PM. REPRIEVE IN ACTIVITY WILL BE SHORT IN THE MID AFTERNOON...WITH LIGHT ISOLATED SHOWERS POSSIBLE. REDEVELOPMENT OF SHOWERS AND SCATTERED THUNDERSTORMS EXPECTED FROM SOUTHWEST TO NORTHEAST BETWEEN 0-3 UTC. FLIGHT CATS WILL DROP TO IFR WITH 500-1000 FEET CIGS THIS EVENING WITH REDEVELOPMENT...REMAINING THERE THROUGH THU. VSBYS WILL GENERALLY RANGE FROM 1-4 MILES DURING THIS PERIOD. MODERATE TO HEAVY RAINFALL WITH THUNDERSTORMS ARE EXPECTED OVERNIGHT INTO THURSDAY. MARINE... WILL ISSUE MARINE WEATHER STATEMENT OR SPECIAL MARINE WARNING FOR WAKE LOW WIND GUSTS BETWEEN 30 AND 40 KNOTS OVER THE NEARSHORE WATERS THROUGH 00Z THURSDAY. GUSTY OFFSHORE WINDS EXPECTED THURSDAY NIGHT THROUGH FRIDAY ACROSS THE NEARSHORE WATERS...AS LOW PRESSURE STRENGTHENS AND MOVES NORTHEAST OF THE AREA. HIGH WAVES WILL OCCUR TOWARD THE OPEN WATERS DURING THIS TIME. A SMALL CRAFT ADVISORY MAY BE NEEDED IN LATER FORECASTS. && .MKX WATCHES/WARNINGS/ADVISORIES... WI...FLOOD WATCH THROUGH FRIDAY MORNING FOR WIZ046-047-051-052- 056>060-062>072. LM...SMALL CRAFT ADVISORY UNTIL 9 AM CDT THURSDAY FOR LMZ643>646. && $$ UPDATE...HENTZ TONIGHT/THURSDAY AND AVIATION/MARINE...ET THURSDAY NIGHT THROUGH WEDNESDAY...DAVIS
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
904 PM CDT WED APR 17 2013 .UPDATE... ISSUED AT 904 PM CDT WED APR 17 2013 THE NEXT BAND OF RAIN IS CURRENTLY MOVING THROUGH THE REGION AND SHOULD LAST THROUGH THE NEXT 2 TO 4 HOURS PROVIDING ABOUT 0.20 TO 0.40 OF AN INCH OF RAIN. WITH THE MAIN AXIS OF LOW LEVEL MOISTURE TRANSPORT AND HIGHER INSTABILITY STAYING TO THE SOUTHEAST INTO TOMORROW...HAVE DECIDED TO DROP THE FLOOD WATCH FOR THE NORTHWESTERN HALF OF THE FORECAST AREA. WILL HAVE AN UPDATE COMING OUT SHORTLY WITH THIS CANCELLATION. OTHERWISE...LIGHTNING HAS REALLY DWINDLED OVER THE PAST FEW HOURS AS THIS RAIN HAS RUN INTO THE REGION THAT HAS LITTLE TO NO INSTABILITY. THE LAST FEW RUNS OF THE RAP HAVE KEPT THE HIGHER 0-3KM MUCAPE OFF TO THE EAST OF THE FORECAST AREA AS WELL...SO AM NOT ANTICIPATING MUCH IN THE WAY OF HAIL TO OCCUR. DUAL POL RADAR ANALYSIS SHOWS SOME BRIGHT BANDING AS WELL AROUND 6-7KFT WITH ALL LIQUID PRECIPITATION LIKELY MAKING IT DOWN TO THE GROUND. && .SHORT TERM...(THIS EVENING THROUGH THURSDAY) ISSUED AT 305 PM CDT WED APR 17 2013 MAIN FORECAST CONCERNS ARE ON HEAVY RAINFALL TONIGHT THROUGH THURSDAY AND LARGE HAIL POTENTIAL THIS EVENING INTO THE OVERNIGHT HOURS. FOCUS THEN TURNS TO PERSISTENT RAINFALL THROUGH THE DAY ON THURSDAY...WITH PRECIPITATION SWITCHING OVER TO SNOW THURSDAY NIGHT. LATEST WATER VAPOR IMAGERY SHOWED A POTENT TROUGH DIGGING INTO THE FOUR CORNERS REGION WITH SOUTHWEST FLOW ALOFT SETTING UP OVER THE UPPER MISSISSIPPI RIVER VALLEY. A MOIST...UNSTABLE AIRMASS WAS ADVECTING NORTHWARD OUT OF THE MIDDLE MISSISSIPPI RIVER VALLEY AND INTERACTING WITH SHORTWAVE ENERGY EMBEDDED IN THE SOUTHWEST FLOW. SHOWERS AND THUNDERSTORMS HAVE BEEN ONGOING ACROSS ACROSS MUCH OF IOWA THROUGH NORTHERN ILLINOIS AND FAR SOUTHWEST WISCONSIN. THE SURGE OF MOIST UNSTABLE AIR CONTINUES ITS NORTHWARD PROGRESSION TONIGHT ON THE NOSE OF A STRONG LOW LEVEL JET. PRECIPITABLE WATER VALUES CLIMB INTO THE 1 TO 1.5 INCH RANGE...WHICH IS 160 TO 230 PERCENT OF NORMAL. ALSO...MUCAPE VALUES INCREASE TO AROUND 1500J/KG ACROSS EXTREME NORTHEAST IOWA AND FAR SOUTHWEST WISCONSIN THIS EVENING INTO THE OVERNIGHT HOURS...WHERE A FEW STORMS COULD PRODUCE LARGE HAIL. WARM CLOUD DEPTHS ALSO INCREASE TONIGHT TO AROUND 3000 M WHICH ALSO IS CONDUCIVE TO HEAVY RAIN POTENTIAL. OVERALL SHEAR IS RATHER WEAK TONIGHT WITH 1 TO 7 KM BULK SHEAR VALUES OF ONLY 15 TO 25 KTS. A STRONG BAROCLINIC ZONE SETS UP ACROSS THE AREA WITH THE WARMEST AIR LOCATED AROUND 925 MB. PLENTY OF SUPPORT FOR SHOWERS AND THUNDERSTORMS TONIGHT ACROSS THE FORECAST AREA WITH THE BAROCLINIC ZONE COLLOCATED WITH THE RIGHT ENTRANCE REGION OF A 250 MB JET. FORECAST MODELS HAVE BEEN TRENDING SLIGHTLY MORE SOUTHEAST WITH THE HEAVIER RAINFALL AMOUNTS KEEPING THE HIGHEST TOTALS GENERALLY SOUTHEAST OF AN OELWEIN IOWA TO MAUSTON WISCONSIN LINE. 2 TO 3 INCHES OF RAINFALL ARE POSSIBLE OVER THESE AREAS WITH 1 TO 2 INCHES POSSIBLE FOR LOCATIONS TO THE NORTH AND WEST. HOWEVER...THIS WILL GREATLY DEPEND UPON WHICH AREAS THE THUNDERSTORMS TRAIN OVER. FLASH FLOODING IS POSSIBLE TONIGHT IF RAINFALL RATES BECOME HIGH ENOUGH. THE HIGHEST CHANCES FOR FLASH FLOODING APPEAR TO BE OVER EXTREME SOUTHWEST WISCONSIN...MAINLY GRANT...CRAWFORD...AND RICHLAND COUNTIES. WILL HAVE TO KEEP A VERY CLOSE EYE ON THIS SITUATION DURING THE OVERNIGHT HOURS. SHOWERS AND ISOLATED THUNDERSTORMS WILL BE ONGOING INTO THURSDAY MORNING THEN THE HEAVIER RAINFALL WILL FINALLY SHIFT SOUTHEAST OF THE AREA BY THURSDAY AFTERNOON AS THE TROUGH LIFTS NORTH INTO EASTERN SOUTH DAKOTA/NEBRASKA AND CLOSES INTO AN UPPER LOW. COLDER AIR FILTERS INTO THE REGION FROM THE WEST ON THURSDAY POTENTIALLY BRING SOME SNOW TO THE FORECAST AREA. A DRY SLOT PUNCHES INTO THE AREA FROM THE SOUTHWEST ON THURSDAY WITH THE FORECAST AREA LOSING DEEP SATURATION. LIGHT RAIN WILL SWITCH OVER TO DRIZZLE AS THE DRY SLOT MOVES IN. THE UPPER LOW IS EXPECTED TO MOVE ACROSS SOUTHWEST MINNESOTA LATE THURSDAY AFTERNOON THEN ADVANCE NORTHEAST INTO EAST CENTRAL MINNESOTA THURSDAY EVENING. A BAND OF SNOW WILL FALL ON THE THE NORTHERN SIDE OF THE LOW TRACK FROM EASTERN SOUTH DAKOTA...INTO CENTRAL MINNESOTA THROUGH NORTHERN WISCONSIN. THE BULK OF THE FORECAST AREA WILL NOT SEE ICE ALOFT SO WHERE TEMPERATURES DROP BELOW FREEZING SOME LIGHT FREEZING DRIZZLE OR FREEZING RAIN IS POSSIBLE...ESPECIALLY THURSDAY EVENING AS SURFACE TEMPERATURES FALL BELOW FREEZING. ICE FINALLY MOVES IN ALOFT THURSDAY NIGHT. ACROSS PORTIONS OF SOUTHEAST MINNESOTA THROUGH NORTH CENTRAL WISCONSIN...PLAN ON SNOW ACCUMULATIONS OF 1 TO 3 INCHES. NORTHEAST IOWA INTO SOUTHWEST AND CENTRAL WISCONSIN SHOULD SEE ACCUMULATIONS OF 1/2 INCH TO AROUND AN INCH. .LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY) ISSUED AT 305 PM CDT WED APR 17 2013 THE LOW IS EXPECTED TO GRADUALLY PROGRESS NORTHEAST INTO WESTERN UPPER MICHIGAN EARLY FRIDAY MORNING. SNOW SHOWERS WILL CONTINUE ACROSS MUCH OF THE AREA FRIDAY MORNING...THEN SWITCHING OVER MAINLY TO RAIN SHOWERS FRIDAY AFTERNOON. PLAN ON BREEZY WEST/NORTHWEST WINDS THURSDAY NIGHT THROUGH FRIDAY WITH A TIGHT PRESSURE GRADIENT OVER THE REGION WITH SPEEDS OF 15 TO 25 MPH WITH GUSTS TO AROUND 35 MPH POSSIBLE...ESPECIALLY DURING THE DAY ON FRIDAY. HIGH TEMPERATURES ON FRIDAY WILL RANGE FROM THE LOWER 30S OVER NORTHERN WISCONSIN TO AROUND 40 ACROSS NORTHEAST IOWA. CHILLY NORTHWEST FLOW CONTINUES ACROSS THE REGION FRIDAY NIGHT THROUGH SATURDAY AS HIGH PRESSURE BUILDS IN. THERE WILL BE A BRIEF BREAK IN PRECIPITATION CHANCES DURING THE DAY ON SATURDAY AHEAD OF ANOTHER TROUGH MOVING IN FROM THE NORTHERN PLAINS. SKIES WILL START OUT MOSTLY SUNNY ON SATURDAY WITH INCREASING CLOUD EXPECTED DURING THE AFTERNOON HOURS. PLAN ON HIGHS ON SATURDAY RANGING FROM AROUND 40 OVER NORTH CENTRAL WISCONSIN TO THE UPPER 40S ACROSS NORTHEAST IOWA. THE HIGH QUICKLY SLIDES OFF TO THE EAST SATURDAY NIGHT. THE TROUGH LOOKS TO MOVE INTO THE UPPER MISSISSIPPI RIVER VALLEY ON SUNDAY SPREADING SHOWERS ACROSS THE AREA. IF THE PRECIPITATION SPREADS IN SATURDAY NIGHT...A WINTER MIX IS POSSIBLE. ACTIVE SOUTHWEST FLOW SETS UP ONCE AGAIN ACROSS THE REGION GOING INTO NEXT WEEK AS A TROUGH DEVELOPS OVER THE CENTRAL CONUS. SEVERAL WAVES EJECT NORTHEAST OUT OF THE TROUGH AND HAVE THE POTENTIAL TO BRING A FEW ROUNDS OF SHOWERS AND THUNDERSTORMS TO THE AREA. MAJOR DIFFERENCES NOTED IN THE TIMING OF THESE WAVES AND EXACTLY HOW THE TROUGH EVOLVES TUESDAY INTO WEDNESDAY SO WILL HAVE TO KEEP A VERY CLOSE WATCH ON THIS SITUATION. && .AVIATION...(FOR THE 00Z TAFS THROUGH 00Z THURSDAY EVENING) ISSUED AT 641 PM CDT WED APR 17 2013 LIFR TO MVFR CONDITIONS TO PERSIST THROUGH TOMORROW AFTERNOON AS A POTENT LOW PRESSURE SYSTEM MOVES THROUGH THE REGION. CEILINGS AND VISIBILITY HAVE DROPPED AT RST AS A BAND OF DRIZZLE HAS MOVED IN ACROSS MUCH OF SOUTHEAST MINNESOTA. THE NEXT ROUND OF SHOWERS AND THUNDERSTORMS IS TIMED TO MOVE INTO THE REGION AROUND 1Z AND SHOULD BE THROUGH BY 5Z. THESE SHOWERS MAY BRIEFLY BRING CONDITIONS UP A FLIGHT CATEGORY...BUT THEY SHOULD DROP BACK DOWN AFTER THE WAVE MOVES THROUGH AND ANOTHER ROUND OF DRIZZLE MOVES IN. CONFIDENCE IS NOT VERY HIGH WITH WHEN THE NEXT WAVE OF SHOWERS MOVES IN AFTER THIS...BUT IT APPEARS THAT SOMETIME AROUND 11Z OR 12Z IS WHEN THE SHORT TERM FORECAST GUIDANCE BRINGS IT IN. BEYOND THIS...OFF AND ON PERIODS OF DRIZZLE AND RAIN SHOWERS WILL PERSIST THROUGH TOMORROW AFTERNOON WITH THE IFR/MVFR CONDITIONS CONTINUING. && .HYDROLOGY...TONIGHT THROUGH THURSDAY ISSUED AT 305 PM CDT WED APR 17 2013 FLOOD WATCH IN EFFECT THROUGH THURSDAY NIGHT. A VERY MOIST AIR MASS WILL MOVE INTO THE AREA TONIGHT FROM THE MIDDLE MISSISSIPPI RIVER VALLEY...WITH PRECIPITABLE WATER VALUES IN THE 1-1.5 INCH RANGE WHICH IS 160 TO 230 PERCENT ABOVE NORMAL. THIS MOISTURE TRANSPORT AND LIFT...COUPLED WITH UPPER LEVEL DYNAMICS WILL TAP THIS MOISTURE TO PRODUCE 1 TO 3 INCHES OF RAINFALL TONIGHT THROUGH THURSDAY NIGHT. THE HIGHEST AMOUNTS WILL LIKELY BE FOCUSED ACROSS NORTHEAST IA INTO SOUTHWEST WI. ALSO...IF THUNDERSTORMS TRAIN OVER AREAS...FLASH FLOODING IS POSSIBLE TONIGHT INTO EARLY THURSDAY MORNING MAINLY OVER EXTREME NORTHEAST IOWA INTO FAR SOUTHWEST WISCONSIN. WITH MANY RIVERS RUNNING HIGH OR ALREADY IN FLOOD...THIS RAINFALL...ALONG WITH SNOW MELT FROM THE SNOW PACK NORTH OF WISCONSIN HIGHWAY 10 AND STILL SOME FROZEN GROUNDS...WILL HEIGHTEN THE FLOOD THREAT. MANY RIVERS WILL GO INTO...OR BACK INTO...FLOOD. IN ADDITION...THERE WILL BE PONDING OF WATER ON ROADWAYS ALONG WITH STANDING WATER IN LOW LYING AND POOR DRAINAGE AREAS. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...FLOOD WATCH THROUGH LATE THURSDAY NIGHT FOR WIZ042>044-053>055- 061. MN...NONE. IA...FLOOD WATCH THROUGH LATE THURSDAY NIGHT FOR IAZ011-029-030. && $$ UPDATE...HALBACH SHORT TERM...WETENKAMP LONG TERM...WETENKAMP AVIATION...HALBACH HYDROLOGY...WETENKAMP
FORECAST DISCUSSION FOR ROUTINE AFTERNOON FORECAST ISSUANCE

.SHORT TERM...TONIGHT AND WEDNESDAY ISSUED AT 308 PM CDT TUE APR 16 2013 LATEST RUC ANALYSIS AND SATELLITE/RADAR IMAGERY SHOW HIGH PRESSURE CENTERED OVER CENTRAL CANADA AND A RIDGE AXIS EXTENDING INTO THE NORTHERN MISSISSIPPI VALLEY. A WEAK COLD FRONT IS EXTENDING ACROSS LAKE SUPERIOR AND NORTHERN MINNESOTA...WHICH IS CONTRIBUTING TO THE WIDESPREAD STRATO-CU FIELD OVER NORTHERN PARTS OF WISCONSIN. THIS STRATO-CU FIELD HAS BEEN SLOWLY RETREATING NORTHWARD THIS AFTERNOON...AND CLEARING SKIES ARE NOW APPROACHING WAUSAU AND MARINETTE AT THIS HOUR. MEANWHILE...CONVECTION IS OCCURRING NORTH OF A STATIONARY FRONT LOCATED ACROSS THE OHIO VALLEY. AS THIS FRONT LIFTS NORTH TOMORROW...THE MAIN FORECAST CONCERN BECOMES TIMING OF THE INCOMING PRECIPITATION. TONIGHT...AS CONVERGENCE ALONG A REINFORCING COLD FRONT WEAKENS...CANADIAN HIGH PRESSURE WILL FEED IN DRIER AIR...BROUGHT IN BY LIGHT NE WINDS. MAY SEE SCT CLOUD COVER LINGER INTO THE EARLY EVENING HOURS OVER N-C WISCONSIN BEFORE DRY AIR EVENTUALLY WINDS OUT AND SKIES TURN MOSTLY CLEAR. IF AND WHEN THIS OCCURS...TEMPS WILL HAVE POTENTIAL TO TANK OVER N-C WISCONSIN WHERE THERE REMAINS DEEP SNOW PACK. HAVE DROPPED LOW TEMPS CONSIDERABLY. OTHERWISE...A WARM FRONT WILL BE LIFTING NORTH ACROSS THE MID-MISSISSIPPI VALLEY...AND MID CLOUDS WILL SPREAD NORTH OVER CENTRAL AND EAST-CENTRAL WISCONSIN AFTER MIDNIGHT. THE DRY AIR FEED TO KEEP PRECIP WELL SOUTH OF THE REGION THOUGH. LOWS RANGING FROM AROUND 20 DEGREES NORTH TO THE MID 30S SOUTH. WEDNESDAY...THE WARM FRONT WILL CONTINUE TO GRADUALLY LIFT NORTH OVER CENTRAL AND NORTHERN ILLINOIS. DRY NE FEED OF AIR WILL TRY TO HOLD BACK PRECIP DURING THE MORNING...AND IT LOOKS LIKE MODELS HAVE SLOWED THE NORTHERLY PROGRESS OF PRECIP CHANCES. WILL GO DRY WITH THE FORECAST THROUGH 18Z. AFTER THAT TIME THOUGH...SOUTHWEST FLOW WILL STRENGTHEN OVER THE FRONT...WHICH SHOULD LEAD TO PRECIP MOVING INTO CENTRAL AND EAST-CENTRAL WISCONSIN DURING THE AFTERNOON. THE PRECIP WILL BE FIGHTING THE DRY AIR...SO THINK THE HEAVIER RAIN WILL NOT ARRIVE UNTIL WEDNESDAY NIGHT...AND FAR NE WISCONSIN MAY NOT SEE A DROP UNTIL AFTER 00Z AS WELL. HIGH TEMPS WILL LIKELY OCCUR MIDDAY OR EARLY AFTERNOON BEFORE CLOUDS THICKEN AND/OR PRECIP STARTS FALLING. PTYPE LIKELY TO BE TRICKY OVER N-C WISCONSIN WHERE THERE WILL BE A +4C WARM NOSE ABOVE SURFACE TEMPS NEAR FREEZING. PREVIOUS SHIFT INCLUDED A RAIN/SLEET MIX...AND THAT LOOKS GOOD COMPARED TO THE PROJECTED SURFACE WET BULB TEMPS. HIGHS IN THE LOW TO MID 40S. .LONG TERM...WEDNESDAY NIGHT THROUGH TUESDAY ISSUED AT 308 PM CDT TUE APR 16 2013 ACTIVE AND COMPLEX WEATHER SITUATION WITH POTENTIAL FOR A COUPLE ROUNDS OF SIGNIFICANT PRECIPITATION FOR THE SECOND HALF OF THE WORK WEEK. SIGNIFICANT TROUGH WILL GRADUALLY SWING INTO THE HIGH PLAINS BY 12Z THURSDAY AND BECOME NEGATIVELY TILTED AND DEEPEN BY FRIDAY AFTERNOON. AS PREVIOUSLY ADVERTISED...STRONG 850 MB JET WILL DEVELOP OVER THE PLAINS EARLY WEDNESDAY EVENING AND WILL BE THE DRIVING FORCE FOR STRONG WAA/LIFT AND SIGNIFICANT MOISTURE TRANSPORT INTO THE WESTERN GREAT LAKES WEDNESDAY NIGHT. LARGE AREA OF MODERATE TO HEAVY PRECIPTATION IS FORECAST TO BREAKOUT FROM EASTERN NEBRASKA TO SOUTHWEST WISCONSIN AND SPREAD NORTHEAST ACROSS THE FORECAST AREA OVERNIGHT INTO EARLY THURSDAY. PRECIPITABLE WATER VALUES OVER THE MISSISSIPPI VALLEY NORTHWARD INTO WISCONSIN EXPECTED TO BE WELL ABOVE NORMAL FOR THIS TIME OF YEAR. COMBINATION OF STRONG FORCING...ANOMALOUSLY HIGH PRECIPITABLE WATER WILL LEAD MODERATE TO HEAVY RAINFALL. THE GENERAL CONCENSUS OF THE LATEST GUIDANCE SEEMS TO BE FOCUSING THE MAXIMUM QPF OVER ABOUT THE SOUTHEAST THIRD OF THE STATE. HELD ONTO THUNDER POTENTIAL...ESPECIALLY OVER THE FOX VALLEY AS WELL WEDNESDAY NIGHT. CANADIAN MODEL WAS FURTHEST NORTH THAN THE OTHER GUIDANCE DURING THIS PERIOD...THUS WAS DISCONTED. THE AREA OF HEAVIEST RAINFALL SHOULD BE EAST OF THE FORECAST AREA BY AROUND NOON THURSDAY. ACROSS THE NORTHWEST PORTION OF THE FOPRECAST AREA...APPEARS BOUNDARY LAYER TEMPERATURES WILL BE VERY CLOSE TO FREEZING...THUS STILL FEEL THERE IS POTENTIAL FOR SOME FREEZING RAIN...MIXED WITH SLEET AND WET SNOW PARTICULARLY IN THE 06Z TO 12Z PERIOD THURSDAY MORNING. UPPER SYSTEM THEN BECOMES NEGATIVELY TILTED THURSDAY EVENING WITH SURFACE WAVE RAPIDLY INTENSIFYING. PROBLEM IS THAT STILL MUCH DESCREPANCY IN MODEL GUIDANCE WITH RESPECT TO THE RATE OF DEEPENING AND MOVEMENT OF THE SURFACE LOW. THUS...HAD TO REAMIN SOMEWHAT BROAD BRUSH ON QPF AMOUNTS ACROSS THE FORECAST AREA. IT DOES APPEAR THAT BY EARLY FRIDAY MORNING ENOUGH COLD AIR WILL BE DRAWN INTO THE SYSTEM TO TURN THE PRECIPITATION OVER TO SNOW. LATER SHIFTS SHOULD BE ABLE GET A BETTER HANDLE ON THE SYSTEM EVOLUTION AND ASSOCIATED PRECIPITATION TYPES. GIVEN THE POTENTIAL FOR A COUPLE ROUNDS OF MODERATE TO HEAVY RAINFALL...MELTING SNOW AND MANY RIVERS AT OR ABOVE FLOOD STAGE ALREADY...AREAL FLOOD WATCH HAS BEEN ISSUED. SEE ASSOCIATED HYDROLOGY DISCUSSION FOR DETAILS BELOW. LOOKS LIKE QUIETER AND DRIER CONDITIONS TO RETURN OVER THE UPCOMING WEEKEND...ALTHOUGH TEMPERATUES WILL REMAIN WELL BELOW NORMAL INTO EARLY NEXT WEEK. && .AVIATION...FOR 18Z TAF ISSUANCE ISSUED AT 1222 PM CDT TUE APR 16 2013 12Z SOUNDINGS INDICATE CLOUD COVER OVER CENTRAL AND NORTHERN WISCONSIN IS RELATIVELY SHALLOW...SO ANTICIPATING CLOUDS TO BREAK UP WITH HEATING THIS AFTERNOON. REGARDLESS...CIGS SHOULD INCREASE TO VFR THIS AFTERNOON. HIGH PRESSURE WILL THEN HANG AROUND THE REGION TONIGHT AS MID CLOUDS INCREASE AHEAD OF THE NEXT SYSTEM DEVELOPING OVER THE PLAINS. A WARM FRONT THEN LIFTS NORTH INTO NORTHERN ILLINOIS ON WEDNESDAY. CLOUDS WILL LOWER AND THICKEN THROUGH THE DAY AS MOISTURE FLOWS NORTH. INITIAL LOW LEVEL DRY AIR WILL HOLD BACK THE PRECIPITATION SOMEWHAT...BUT STILL EXPECT LIGHT RAIN...POSSIBLY MIXED WITH SNOW OVER NORTHERN WISCONSIN TO ARRIVE WEDNESDAY AFTERNOON. && .HYDROLOGY... ISSUED AT 308 PM CDT TUE APR 16 2013 POTENTIAL OF FLOODING ON THE INCREASE THIS WEEK WITH EVEN LONG TERM ISSUES THROUGH APRIL. A STRENGTHENING LOW PRESSURE SYSTEM WILL TRACK NORTHEAST TOWARD THE GREAT LAKES REGION THROUGH FRIDAY. GULF MOISTURE WILL WORK NORTHWARD TO PRODUCE WELL ABOVE NORMAL PRECIPITABLE WATER AMOUNTS FOR THIS TIME OF THE YEAR. RIVERS OVER MUCH OF CENTRAL AND EAST CENTRAL WISCONSIN ALREADY RUNNING HIGH. ADDITIONAL OR LINGERING SNOW MELT WILL BE AVAILABLE OVER CENTRAL WISCONSIN RIVERS WHILE AREAS WITH LITTLE SNOW LEFT...THE GROUND IS SATURATED ALONG WITH A DEPARTING FROST TO PRODUCE ABOVE NORMAL RUN OFF. CONSENSUS OF AVAILABLE MODEL RUNS FOR A TOTAL RAINFALL AMOUNT FROM LATE WEDNESDAY AFTERNOON THROUGH FRIDAY MORNING INDICATE AROUND 2 INCHES OF RAIN SOUTHEAST OF A LINE FROM GREEN BAY TO WAUTOMA...AND UP TO 1.5 INCHES NORTHWARD. THE RAIN WILL BE FOCUSED ALONG OR NEAR A SOUTHWEST TO NORTHEAST BOUNDARY EXTENDING OVER SOUTHEAST WISCONSIN. ANY THUNDERSTORMS WHICH CAN DEVELOP...WILL LIKELY INCREASE THE RAINFALL TOTALS. NORTH CENTRAL WISCONSIN COULD SEE A RAIN TO SNOW MIX BY FRIDAY FOR LESSER RAINFALL BUT ADDITIONAL SNOWFALL TO THE PERSISTENT SNOW PACK. WILL ISSUE A FFA AREAL FLOOD WARNING FOR CENTRAL AND EAST CENTRAL WISCONSIN THROUGH FRIDAY. WILL CONSIDER AN ESF NORTH. THE AREAL FLOOD WARNING WILL LIKE TRANSITION TO RIVER FLOOD WARNINGS BY THIS WEEKEND. FOR A LONGER TERM FLOODING ISSUE DEVELOPING...THE INCREASING FLOWS ON THE FOX AND WOLF RIVERS COMING INTO LAKE WINNEBAGO WILL EVENTUALLY CAUSE THE LAKE TO RISE AND REMAIN FAIRLY HIGH FOR MUCH OF APRIL IF PERIODS OF RAIN CONTINUE. THE COMBINATION OF STRONG WINDS WITH HIGHER THAN NORMAL LAKE WINNEBAGO LAKE LEVELS WILL INCREASE THE POTENTIAL OF SHORELINE FLOODING. HIGH LAKE WINNEBAGO LEVELS WILL LIKELY TEND TO PRODUCE LONG TERM HIGH LEVELS UPSTREAM ON THE WOLF AND FOX RIVERS THROUGH APRIL...AGAIN DEPENDING ADDITIONAL RAINFALL. && .GRB WATCHES/WARNINGS/ADVISORIES... FLOOD WATCH FROM WEDNESDAY EVENING THROUGH FRIDAY MORNING FOR WIZ020>022-030-031-035>040-045-048>050-073-074. && $$ SHORT TERM.....MPC LONG TERM......ESB AVIATION.......MPC HYDROLOGY......MPC
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
1213 PM CDT TUE APR 16 2013 .SHORT TERM...(TODAY THROUGH TONIGHT) ISSUED AT 354 AM CDT TUE APR 16 2013 WATER VAPOR IMAGERY AND RAP 500MB ANALYSIS SHOWS A BROAD/RELATIVELY DEEP UPPER TROUGH AXIS SITUATED OVER THE WEST COAST/INTERMOUNTAIN REGION. SOUTHWEST FLOW ALOFT OUT F THIS TROUGH WAS SPILLING QUITE A BIT OF MID/HIGH CLOUD INTO THE REGION. AT THE SURFACE...THE FORECAST AREA WAS STILL UNDER THE INFLUENCE OF THE LOW PRESSURE THAT BROUGHT A WINTRY MIX/RAINFALL INTO THE AREA OVER THE WEEKEND. CYCLONIC FLOW AROUND THE LOW OVER SOUTHERN ONTARIO WAS PRODUCING AN EXTENSIVE STRATOCUMULUS FILED ACROSS NORTHERN MN INTO NORTHER WI. OTHERWISE...TEMPERATURES AT 3 AM WERE IN THE 30S. MAIN FORECAST CHALLENGE IN THE SHORT TERM WILL BE CLOUDS AND TEMPERATURES THROUGH TONIGHT. 16.00Z NCEP MODEL SUITE AS WELL AS THE ECMWF AND GEM ALL IN GOOD AGREEMENT IN THE SHORT TERM. FOR TODAY...WILL SEE THE LOW OVER ONTARIO LIFT FARTHER EAST INTO QUEBEC...WITH HIGH PRESSURE BUILDING IN FROM THE NORTHERN PLAINS. THIS WILL KEEP US DRY...BUT SOUTHWEST FLOW ALOFT WILL CONTINUE TO SPILL MID/HIGH CLOUD INTO THE REGION. NOT TOO CONFIDENT HOW THICK THIS CLOUD COVER WILL BE. BUFKIT SHOWS ALTERNATE THICKENING/THINNING THROUGH THE DAY. FEEL WE SEE SOMEWHERE BETWEEN 40-60 PERCENT OPAQUENESS FOR PARTLY TO MOSTLY SUNNY CONDITIONS. TEMPERATURES TODAY EXPECTED TO TOP OFF IN THE MIDDLE 40S ACROSS NORTH CENTRAL WI...TO THE LOWER 50S ACROSS PORTIONS OF NORTHEAST IOWA INTO SOUTHWEST WI. CLOUDS WILL THEN THICKEN TONIGHT AHEAD OF FAIRLY STRONG CYCLOGENESIS EAST OF THE COLORADO ROCKY MOUNTAIN FRONT WITH INCREASING MOISTURE TRANSPORT AND ISENTROPIC LIFT. MOISTURE WILL BE BATTLING DRY AIR INITIALLY...BUT FEEL SOME RAIN WILL BE POSSIBLE ACROSS NORTHEAST IA/SOUTHEAST MN/FAR SOUTHWEST WI TOWARD MORNING. OTHERWISE...WITH THICKENING CLOUDS...LOOK FOR TEMPERATURES TO RANGE FROM NEAR 30 ACROSS NORTH CENTRAL WI...TO THE MIDDLE AND UPPER 30S ACROSS NORTHEAST IA INTO SOUTHWEST WI. .LONG TERM...(WEDNESDAY THROUGH MONDAY) ISSUED AT 354 AM CDT TUE APR 16 2013 LOOK FOR RAIN TO OVERSPREAD THE AREA ON WEDNESDAY AS STRONG LOW PRESSURE MOVING OUT INTO THE PLAINS INCREASES MOISTURE TRANSPORT INTO THE AREA. NAM ALSO INDICATING SOME ELEVATED MUCAPE OF A COUPLE HUNDRED J/KG GOING INTO THE AFTER NOON FOR PERHAPS A CLAP OR TWO OF THUNDER. RAINFALL EXPECTED TO REALLY PICK UP OVER THE AREA WEDNESDAY AFTERNOON/NIGHT AS THE LOW MOVES FROM MO INTO SOUTHEAST WI. SREF INDICATING INCREASING 850-700MB FRONTOGENESIS OVER THE FORECAST AREA NORTHWEST OF THE LOW ALONG WITH INCREASING MOISTURE TRANSPORT... WITH PRECIPITABLE WATERS MOVING INTO THE 1-1.5 INCH RANGE. RAIN RATES COULD GET MODERATE TO HEAVY AT TIMES GIVEN THIS SCENARIO. RAIN THEN EXPECTED TO TAPER OFF ON THURSDAY AS THE LOW PULLS INTO LOWER MI. THINKING THAT FOCUSED FORCING ALONG WITH MUCH HIGHER THAN NORMAL PRECIPITABLE WATER VALUES WILL YIELD RAINFALL AMOUNTS SOMEWHERE IN THE 1.5-3.5 INCH RANGE WITH A FEW LOCALLY HIGHER AMOUNTS GIVEN THE EMBEDDED THUNDERSTORM POTENTIAL. HYDROLOGY EXPECTED TO BECOME AN ISSUE ONCE AGAIN WITH RIVERS RUNNING FAIRLY HIGH RIGHT NOW. MORE ON THIS IS COVERED IN THE HYDROLOGY SECTION BELOW. CONCERN IS INCREASING THAT A FLOOD WATCH MAY BECOME NECESSARY AS WELL WITH SATURATED GROUND AND POTENTIAL FOR OVERLAND FLOODING IN ADDITION TO RIVER FLOODING SINCE OUR 6-HRLY FLASH FLOOD GUIDANCE IS ONLY RUNNING 2-3 INCHES. WILL HAVE THE DAY SHIFT ASSESS THIS WITH THE 12Z MODEL RUNS. ATTENTION THEN TURNS TO SIGNIFICANT SNOWFALL POTENTIAL FOR THURSDAY NIGHT INTO FRIDAY. MODELS ARE BECOMING MORE IN AGREEMENT AND CONSISTENT WITH INCREASING SNOW SIGNAL FOR THE AREA. ECMWF/GFS/GEM ALL BRING ANOTHER WAVE OF LOW PRESSURE UP ALONG THE EXISTING BAROCLINIC ZONE AS A VIGOROUS MID-LEVEL TROUGH/CLOSED LOW MOVES TOWARD THE AREA FROM THE PLAINS. STRONG DEFORMATION ZONE THEN SETS UP ACROSS THE NORTHWEST HALF OF THE FORECAST AREA. LATEST GFS COB WANTS TO PRODUCE 8+ INCHES/LOCALLY HIGHER AMOUNTS NORTHWEST OF A LINE ROUGHLY RUNNING FROM MEDFORD AND LA CROSSE WI...TO NEAR OELWEIN IA. HEADLINES WILL LIKELY BE NEEDED. WILL PASS THIS ONTO THE DAYSHIFT AS WELL FOR FURTHER ASSESSMENT. FRIDAY NIGHT THROUGH SATURDAY LOOKS DRY WITH HIGH PRESSURE MOVING IN. PRECIPITATION CHANCES WILL RETURN SATURDAY NIGHT THROUGH MONDAY AS LOW PRESSURE MOVES ACROSS THE NORTHERN PLAINS INTO THE UPPER MISSISSIPPI RIVER VALLEY REGION. OTHERWISE...LOOK FOR BELOW NORMAL TEMPERATURES TO CONTINUE THROUGH THE WEEKEND...POSSIBLY GETTING TO NEAR NORMAL BY MONDAY. && .AVIATION...THROUGH 18Z WEDNESDAY 1208 PM CDT TUE APR 16 2013 MVFR CLOUDS TO SLOWLY CLEAR THIS AFTERNOON AND GIVE WAY TO VFR CONDITIONS UNTIL A MAJOR WEATHER SYSTEM MOVES IN FOR WEDNESDAY AND THURSDAY. MOISTURE WILL INCREASE SUBSTANTIALLY IN THE ATMOSPHERE OVER THE TAF SITES WEDNESDAY MORNING WITH DETERIORATING CONDITIONS EXPECTED THROUGH THE DAY IN -RA/RA. PERIODIC IFR CIGS/VSBYS ARE POSSIBLE LATER WEDNESDAY AND INTO THURSDAY. THUS...CONDITIONS WILL BE BEST FOR AVIATION USERS IN THE MORNING WEDNESDAY. A CHANGE TO ACCUMULATING SNOW WILL OCCUR THURSDAY NIGHT AT KRST AND IFR CONDITIONS LOOK LIKELY INTO FRIDAY. && .HYDROLOGY...MAINLY WEDNESDAY AND WEDNESDAY NIGHT ISSUED AT 354 AM CDT TUE APR 16 2013 ADDITIONAL RAINFALL WED/WED NIGHT/THU POSES A FLOODING THREAT FOR MOST IF NOT ALL RIVERS AND STREAMS IN OUR FORECAST AREA. RUNOFF FROM EXPECTED 1.5 TO 3.5 INCHES OF RAINFALL FROM WED THROUGH THU WILL LIKELY PRODUCE ADDITIONAL RISES ON THE TRIBUTARY RIVERS/ STREAMS THAT ARE ALREADY RUNNING HIGH FROM RECENT RAINFALL AND SNOW MELT THIS PAST WEEK. GIVEN THIS EXPECTED RAINFALL ALONG WITH LOCALIZED HIGHER RAINFALL RATES...ADDITIONAL FLOODING IS POSSIBLE IF NOT LIKELY ON THE TRIBUTARY RIVERS LATER IN THE WEEK INTO THE WEEKEND. WILL CONTINUE HYDROLOGIC OUTLOOK PRODUCT ADDRESSING THE RAIN/FLOODING THREATS LATER IN THE WEEK. LOOK FOR WATER LEVELS ON THE MISSISSIPPI RIVER TO REMAIN NEARLY STEADY OR GRADUALLY RISE THIS WEEK AS RUNOFF FROM RECENT RAINS AND SNOWMELT MOVES DOWNSTREAM. THE ADDITIONAL RAINS ON WEDNESDAY THROUGH THURSDAY WOULD CREATE ADDITIONAL RISES ON THE MISSISSIPPI RIVER...BUT MOST OF THESE RISES FROM THE WED-THU RAINS EXPECTED NOT TO SHOW UP IN THE MISSISSIPPI RIVER UNTIL EARLY NEXT WEEK. && .ARX WATCHES/WARNINGS/ADVISORIES... 1208 PM CDT TUE APR 16 2013 WI...FLOOD WATCH FROM WEDNESDAY AFTERNOON THROUGH LATE THURSDAY NIGHT FOR WIZ017-029-032>034-041>044-053>055-061. MN...FLOOD WATCH FROM WEDNESDAY AFTERNOON THROUGH LATE THURSDAY NIGHT FOR MNZ079-086>088-094>096. IA...FLOOD WATCH FROM WEDNESDAY AFTERNOON THROUGH LATE THURSDAY NIGHT FOR IAZ008>011-018-019-029-030. && $$ SHORT TERM...DAS LONG TERM....DAS AVIATION...BAUMGARDT HYDROLOGY....DAS/RRS
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
629 AM CDT TUE APR 16 2013 .SHORT TERM...(TODAY THROUGH TONIGHT) ISSUED AT 354 AM CDT TUE APR 16 2013 WATER VAPOR IMAGERY AND RAP 500MB ANALYSIS SHOWS A BROAD/RELATIVELY DEEP UPPER TROUGH AXIS SITUATED OVER THE WEST COAST/INTERMOUNTAIN REGION. SOUTHWEST FLOW ALOFT OUT F THIS TROUGH WAS SPILLING QUITE A BIT OF MID/HIGH CLOUD INTO THE REGION. AT THE SURFACE...THE FORECAST AREA WAS STILL UNDER THE INFLUENCE OF THE LOW PRESSURE THAT BROUGHT A WINTRY MIX/RAINFALL INTO THE AREA OVER THE WEEKEND. CYCLONIC FLOW AROUND THE LOW OVER SOUTHERN ONTARIO WAS PRODUCING AN EXTENSIVE STRATOCUMULUS FILED ACROSS NORTHERN MN INTO NORTHER WI. OTHERWISE...TEMPERATURES AT 3 AM WERE IN THE 30S. MAIN FORECAST CHALLENGE IN THE SHORT TERM WILL BE CLOUDS AND TEMPERATURES THROUGH TONIGHT. 16.00Z NCEP MODEL SUITE AS WELL AS THE ECMWF AND GEM ALL IN GOOD AGREEMENT IN THE SHORT TERM. FOR TODAY...WILL SEE THE LOW OVER ONTARIO LIFT FARTHER EAST INTO QUEBEC...WITH HIGH PRESSURE BUILDING IN FROM THE NORTHERN PLAINS. THIS WILL KEEP US DRY...BUT SOUTHWEST FLOW ALOFT WILL CONTINUE TO SPILL MID/HIGH CLOUD INTO THE REGION. NOT TOO CONFIDENT HOW THICK THIS CLOUD COVER WILL BE. BUFKIT SHOWS ALTERNATE THICKENING/THINNING THROUGH THE DAY. FEEL WE SEE SOMEWHERE BETWEEN 40-60 PERCENT OPAQUENESS FOR PARTLY TO MOSTLY SUNNY CONDITIONS. TEMPERATURES TODAY EXPECTED TO TOP OFF IN THE MIDDLE 40S ACROSS NORTH CENTRAL WI...TO THE LOWER 50S ACROSS PORTIONS OF NORTHEAST IOWA INTO SOUTHWEST WI. CLOUDS WILL THEN THICKEN TONIGHT AHEAD OF FAIRLY STRONG CYCLOGENESIS EAST OF THE COLORADO ROCKY MOUNTAIN FRONT WITH INCREASING MOISTURE TRANSPORT AND ISENTROPIC LIFT. MOISTURE WILL BE BATTLING DRY AIR INITIALLY...BUT FEEL SOME RAIN WILL BE POSSIBLE ACROSS NORTHEAST IA/SOUTHEAST MN/FAR SOUTHWEST WI TOWARD MORNING. OTHERWISE...WITH THICKENING CLOUDS...LOOK FOR TEMPERATURES TO RANGE FROM NEAR 30 ACROSS NORTH CENTRAL WI...TO THE MIDDLE AND UPPER 30S ACROSS NORTHEAST IA INTO SOUTHWEST WI. .LONG TERM...(WEDNESDAY THROUGH MONDAY) ISSUED AT 354 AM CDT TUE APR 16 2013 LOOK FOR RAIN TO OVERSPREAD THE AREA ON WEDNESDAY AS STRONG LOW PRESSURE MOVING OUT INTO THE PLAINS INCREASES MOISTURE TRANSPORT INTO THE AREA. NAM ALSO INDICATING SOME ELEVATED MUCAPE OF A COUPLE HUNDRED J/KG GOING INTO THE AFTER NOON FOR PERHAPS A CLAP OR TWO OF THUNDER. RAINFALL EXPECTED TO REALLY PICK UP OVER THE AREA WEDNESDAY AFTERNOON/NIGHT AS THE LOW MOVES FROM MO INTO SOUTHEAST WI. SREF INDICATING INCREASING 850-700MB FRONTOGENESIS OVER THE FORECAST AREA NORTHWEST OF THE LOW ALONG WITH INCREASING MOISTURE TRANSPORT... WITH PRECIPITABLE WATERS MOVING INTO THE 1-1.5 INCH RANGE. RAIN RATES COULD GET MODERATE TO HEAVY AT TIMES GIVEN THIS SCENARIO. RAIN THEN EXPECTED TO TAPER OFF ON THURSDAY AS THE LOW PULLS INTO LOWER MI. THINKING THAT FOCUSED FORCING ALONG WITH MUCH HIGHER THAN NORMAL PRECIPITABLE WATER VALUES WILL YIELD RAINFALL AMOUNTS SOMEWHERE IN THE 1.5-3.5 INCH RANGE WITH A FEW LOCALLY HIGHER AMOUNTS GIVEN THE EMBEDDED THUNDERSTORM POTENTIAL. HYDROLOGY EXPECTED TO BECOME AN ISSUE ONCE AGAIN WITH RIVERS RUNNING FAIRLY HIGH RIGHT NOW. MORE ON THIS IS COVERED IN THE HYDROLOGY SECTION BELOW. CONCERN IS INCREASING THAT A FLOOD WATCH MAY BECOME NECESSARY AS WELL WITH SATURATED GROUND AND POTENTIAL FOR OVERLAND FLOODING IN ADDITION TO RIVER FLOODING SINCE OUR 6-HRLY FLASH FLOOD GUIDANCE IS ONLY RUNNING 2-3 INCHES. WILL HAVE THE DAY SHIFT ASSESS THIS WITH THE 12Z MODEL RUNS. ATTENTION THEN TURNS TO SIGNIFICANT SNOWFALL POTENTIAL FOR THURSDAY NIGHT INTO FRIDAY. MODELS ARE BECOMING MORE IN AGREEMENT AND CONSISTENT WITH INCREASING SNOW SIGNAL FOR THE AREA. ECMWF/GFS/GEM ALL BRING ANOTHER WAVE OF LOW PRESSURE UP ALONG THE EXISTING BAROCLINIC ZONE AS A VIGOROUS MID-LEVEL TROUGH/CLOSED LOW MOVES TOWARD THE AREA FROM THE PLAINS. STRONG DEFORMATION ZONE THEN SETS UP ACROSS THE NORTHWEST HALF OF THE FORECAST AREA. LATEST GFS COB WANTS TO PRODUCE 8+ INCHES/LOCALLY HIGHER AMOUNTS NORTHWEST OF A LINE ROUGHLY RUNNING FROM MEDFORD AND LA CROSSE WI...TO NEAR OELWEIN IA. HEADLINES WILL LIKELY BE NEEDED. WILL PASS THIS ONTO THE DAYSHIFT AS WELL FOR FURTHER ASSESSMENT. FRIDAY NIGHT THROUGH SATURDAY LOOKS DRY WITH HIGH PRESSURE MOVING IN. PRECIPITATION CHANCES WILL RETURN SATURDAY NIGHT THROUGH MONDAY AS LOW PRESSURE MOVES ACROSS THE NORTHERN PLAINS INTO THE UPPER MISSISSIPPI RIVER VALLEY REGION. OTHERWISE...LOOK FOR BELOW NORMAL TEMPERATURES TO CONTINUE THROUGH THE WEEKEND...POSSIBLY GETTING TO NEAR NORMAL BY MONDAY. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z WEDNESDAY MORNING) ISSUED AT 629 AM CDT TUE APR 16 2013 AN AREA OF STRATUS GENERALLY NORTH OF INTERSTATE 90 WAS SLOWLY SAGGING SOUTHWARD. RAP AND NAM BUFKIT SOUNDINGS INDICATE THESE SHOULD MIX OUT BY MID TO LATE MORNING WITH VFR CONDITIONS AFTER THAT. MOISTURE TRANSPORT WILL INCREASE LATE TONIGHT AHEAD OF A DEVELOPING STORMS SYSTEM OVER THE PLAINS. THIS WILL SPREAD A MID DECK OF CLOUDS INTO THE TAF SITES...BUT ANY PRECIPITATION SHOULD HOLD OFF UNTIL AFTER 12Z. && .HYDROLOGY...MAINLY WEDNESDAY AND WEDNESDAY NIGHT ISSUED AT 354 AM CDT TUE APR 16 2013 ADDITIONAL RAINFALL WED/WED NIGHT/THU POSES A FLOODING THREAT FOR MOST IF NOT ALL RIVERS AND STREAMS IN OUR FORECAST AREA. RUNOFF FROM EXPECTED 1.5 TO 3.5 INCHES OF RAINFALL FROM WED THROUGH THU WILL LIKELY PRODUCE ADDITIONAL RISES ON THE TRIBUTARY RIVERS/ STREAMS THAT ARE ALREADY RUNNING HIGH FROM RECENT RAINFALL AND SNOW MELT THIS PAST WEEK. GIVEN THIS EXPECTED RAINFALL ALONG WITH LOCALIZED HIGHER RAINFALL RATES...ADDITIONAL FLOODING IS POSSIBLE IF NOT LIKELY ON THE TRIBUTARY RIVERS LATER IN THE WEEK INTO THE WEEKEND. WILL CONTINUE HYDROLOGIC OUTLOOK PRODUCT ADDRESSING THE RAIN/FLOODING THREATS LATER IN THE WEEK. LOOK FOR WATER LEVELS ON THE MISSISSIPPI RIVER TO REMAIN NEARLY STEADY OR GRADUALLY RISE THIS WEEK AS RUNOFF FROM RECENT RAINS AND SNOWMELT MOVES DOWNSTREAM. THE ADDITIONAL RAINS ON WEDNESDAY THROUGH THURSDAY WOULD CREATE ADDITIONAL RISES ON THE MISSISSIPPI RIVER...BUT MOST OF THESE RISES FROM THE WED-THU RAINS EXPECTED NOT TO SHOW UP IN THE MISSISSIPPI RIVER UNTIL EARLY NEXT WEEK. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...NONE. MN...NONE. IA...NONE. && $$ SHORT TERM...DAS LONG TERM....DAS AVIATION...RABERDING HYDROLOGY....DAS/RRS
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
354 AM CDT TUE APR 16 2013 .SHORT TERM...(TODAY THROUGH TONIGHT) ISSUED AT 354 AM CDT TUE APR 16 2013 WATER VAPOR IMAGERY AND RAP 500MB ANALYSIS SHOWS A BROAD/RELATIVELY DEEP UPPER TROUGH AXIS SITUATED OVER THE WEST COAST/INTERMOUNTAIN REGION. SOUTHWEST FLOW ALOFT OUT F THIS TROUGH WAS SPILLING QUITE A BIT OF MID/HIGH CLOUD INTO THE REGION. AT THE SURFACE...THE FORECAST AREA WAS STILL UNDER THE INFLUENCE OF THE LOW PRESSURE THAT BROUGHT A WINTRY MIX/RAINFALL INTO THE AREA OVER THE WEEKEND. CYCLONIC FLOW AROUND THE LOW OVER SOUTHERN ONTARIO WAS PRODUCING AN EXTENSIVE STRATOCUMULUS FILED ACROSS NORTHERN MN INTO NORTHER WI. OTHERWISE...TEMPERATURES AT 3 AM WERE IN THE 30S. MAIN FORECAST CHALLENGE IN THE SHORT TERM WILL BE CLOUDS AND TEMPERATURES THROUGH TONIGHT. 16.00Z NCEP MODEL SUITE AS WELL AS THE ECMWF AND GEM ALL IN GOOD AGREEMENT IN THE SHORT TERM. FOR TODAY...WILL SEE THE LOW OVER ONTARIO LIFT FARTHER EAST INTO QUEBEC...WITH HIGH PRESSURE BUILDING IN FROM THE NORTHERN PLAINS. THIS WILL KEEP US DRY...BUT SOUTHWEST FLOW ALOFT WILL CONTINUE TO SPILL MID/HIGH CLOUD INTO THE REGION. NOT TOO CONFIDENT HOW THICK THIS CLOUD COVER WILL BE. BUFKIT SHOWS ALTERNATE THICKENING/THINNING THROUGH THE DAY. FEEL WE SEE SOMEWHERE BETWEEN 40-60 PERCENT OPAQUENESS FOR PARTLY TO MOSTLY SUNNY CONDITIONS. TEMPERATURES TODAY EXPECTED TO TOP OFF IN THE MIDDLE 40S ACROSS NORTH CENTRAL WI...TO THE LOWER 50S ACROSS PORTIONS OF NORTHEAST IOWA INTO SOUTHWEST WI. CLOUDS WILL THEN THICKEN TONIGHT AHEAD OF FAIRLY STRONG CYCLOGENESIS EAST OF THE COLORADO ROCKY MOUNTAIN FRONT WITH INCREASING MOISTURE TRANSPORT AND ISENTROPIC LIFT. MOISTURE WILL BE BATTLING DRY AIR INITIALLY...BUT FEEL SOME RAIN WILL BE POSSIBLE ACROSS NORTHEAST IA/SOUTHEAST MN/FAR SOUTHWEST WI TOWARD MORNING. OTHERWISE...WITH THICKENING CLOUDS...LOOK FOR TEMPERATURES TO RANGE FROM NEAR 30 ACROSS NORTH CENTRAL WI...TO THE MIDDLE AND UPPER 30S ACROSS NORTHEAST IA INTO SOUTHWEST WI. .LONG TERM...(WEDNESDAY THROUGH MONDAY) ISSUED AT 354 AM CDT TUE APR 16 2013 LOOK FOR RAIN TO OVERSPREAD THE AREA ON WEDNESDAY AS STRONG LOW PRESSURE MOVING OUT INTO THE PLAINS INCREASES MOISTURE TRANSPORT INTO THE AREA. NAM ALSO INDICATING SOME ELEVATED MUCAPE OF A COUPLE HUNDRED J/KG GOING INTO THE AFTER NOON FOR PERHAPS A CLAP OR TWO OF THUNDER. RAINFALL EXPECTED TO REALLY PICK UP OVER THE AREA WEDNESDAY AFTERNOON/NIGHT AS THE LOW MOVES FROM MO INTO SOUTHEAST WI. SREF INDICATING INCREASING 850-700MB FRONTOGENESIS OVER THE FORECAST AREA NORTHWEST OF THE LOW ALONG WITH INCREASING MOISTURE TRANSPORT... WITH PRECIPITABLE WATERS MOVING INTO THE 1-1.5 INCH RANGE. RAIN RATES COULD GET MODERATE TO HEAVY AT TIMES GIVEN THIS SCENARIO. RAIN THEN EXPECTED TO TAPER OFF ON THURSDAY AS THE LOW PULLS INTO LOWER MI. THINKING THAT FOCUSED FORCING ALONG WITH MUCH HIGHER THAN NORMAL PRECIPITABLE WATER VALUES WILL YIELD RAINFALL AMOUNTS SOMEWHERE IN THE 1.5-3.5 INCH RANGE WITH A FEW LOCALLY HIGHER AMOUNTS GIVEN THE EMBEDDED THUNDERSTORM POTENTIAL. HYDROLOGY EXPECTED TO BECOME AN ISSUE ONCE AGAIN WITH RIVERS RUNNING FAIRLY HIGH RIGHT NOW. MORE ON THIS IS COVERED IN THE HYDROLOGY SECTION BELOW. CONCERN IS INCREASING THAT A FLOOD WATCH MAY BECOME NECESSARY AS WELL WITH SATURATED GROUND AND POTENTIAL FOR OVERLAND FLOODING IN ADDITION TO RIVER FLOODING SINCE OUR 6-HRLY FLASH FLOOD GUIDANCE IS ONLY RUNNING 2-3 INCHES. WILL HAVE THE DAY SHIFT ASSESS THIS WITH THE 12Z MODEL RUNS. ATTENTION THEN TURNS TO SIGNIFICANT SNOWFALL POTENTIAL FOR THURSDAY NIGHT INTO FRIDAY. MODELS ARE BECOMING MORE IN AGREEMENT AND CONSISTENT WITH INCREASING SNOW SIGNAL FOR THE AREA. ECMWF/GFS/GEM ALL BRING ANOTHER WAVE OF LOW PRESSURE UP ALONG THE EXISTING BAROCLINIC ZONE AS A VIGOROUS MID-LEVEL TROUGH/CLOSED LOW MOVES TOWARD THE AREA FROM THE PLAINS. STRONG DEFORMATION ZONE THEN SETS UP ACROSS THE NORTHWEST HALF OF THE FORECAST AREA. LATEST GFS COB WANTS TO PRODUCE 8+ INCHES/LOCALLY HIGHER AMOUNTS NORTHWEST OF A LINE ROUGHLY RUNNING FROM MEDFORD AND LA CROSSE WI...TO NEAR OELWEIN IA. HEADLINES WILL LIKELY BE NEEDED. WILL PASS THIS ONTO THE DAYSHIFT AS WELL FOR FURTHER ASSESSMENT. FRIDAY NIGHT THROUGH SATURDAY LOOKS DRY WITH HIGH PRESSURE MOVING IN. PRECIPITATION CHANCES WILL RETURN SATURDAY NIGHT THROUGH MONDAY AS LOW PRESSURE MOVES ACROSS THE NORTHERN PLAINS INTO THE UPPER MISSISSIPPI RIVER VALLEY REGION. OTHERWISE...LOOK FOR BELOW NORMAL TEMPERATURES TO CONTINUE THROUGH THE WEEKEND...POSSIBLY GETTING TO NEAR NORMAL BY MONDAY. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z TUESDAY NIGHT) ISSUED AT 1145 PM CDT MON APR 15 2013 THE AREA OF LOW PRESSURE AT THE SURFACE HAS MOVED NORTHEAST INTO ONTARIO THIS EVENING. THIS HAS ALLOWED THE CYCLONIC FLOW TO RELAX ENOUGH FOR THE WINDS TO DROP DOWN TO ABOUT 10 KNOTS. THE WINDS ARE EXPECTED TO REMAIN AT THIS SPEED THROUGH MUCH OF TUESDAY BEFORE TURNING MORE TO THE NORTHEAST AS WEAK HIGH PRESSURE MOVES BY TO THE NORTH. ENOUGH DRY AIR HAS BEEN PULLED IN TO ALLOW THE LOW AND MID LEVEL CLOUDS TO DISSIPATE LEAVING JUST SOME OCCASIONAL HIGH CLOUDS TO COME IN FROM THE SOUTHWEST. WILL SEE VFR CONDITIONS THROUGH THE PERIOD...BUT MOISTURE FROM THE NEXT SYSTEM WILL BRING IN A CEILING AROUND 10K FEET LATE TUESDAY AFTERNOON OR EVENING WITH THIS GRADUALLY LOWERING THROUGH THE EVENING. && .HYDROLOGY...MAINLY WEDNESDAY AND WEDNESDAY NIGHT ISSUED AT 354 AM CDT TUE APR 16 2013 ADDITIONAL RAINFALL WED/WED NIGHT/THU POSES A FLOODING THREAT FOR MOST IF NOT ALL RIVERS AND STREAMS IN OUR FORECAST AREA. RUNOFF FROM EXPECTED 1.5 TO 3.5 INCHES OF RAINFALL FROM WED THROUGH THU WILL LIKELY PRODUCE ADDITIONAL RISES ON THE TRIBUTARY RIVERS/ STREAMS THAT ARE ALREADY RUNNING HIGH FROM RECENT RAINFALL AND SNOW MELT THIS PAST WEEK. GIVEN THIS EXPECTED RAINFALL ALONG WITH LOCALIZED HIGHER RAINFALL RATES...ADDITIONAL FLOODING IS POSSIBLE IF NOT LIKELY ON THE TRIBUTARY RIVERS LATER IN THE WEEK INTO THE WEEKEND. WILL CONTINUE HYDROLOGIC OUTLOOK PRODUCT ADDRESSING THE RAIN/FLOODING THREATS LATER IN THE WEEK. LOOK FOR WATER LEVELS ON THE MISSISSIPPI RIVER TO REMAIN NEARLY STEADY OR GRADUALLY RISE THIS WEEK AS RUNOFF FROM RECENT RAINS AND SNOWMELT MOVES DOWNSTREAM. THE ADDITIONAL RAINS ON WEDNESDAY THROUGH THURSDAY WOULD CREATE ADDITIONAL RISES ON THE MISSISSIPPI RIVER...BUT MOST OF THESE RISES FROM THE WED-THU RAINS EXPECTED NOT TO SHOW UP IN THE MISSISSIPPI RIVER UNTIL EARLY NEXT WEEK. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...NONE. MN...NONE. IA...NONE. && $$ SHORT TERM...DAS LONG TERM....DAS AVIATION...04 HYDROLOGY....DAS/RRS
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
240 AM CDT THU APR 18 2013 .MESOSCALE DISCUSSION FOR HEAVY RAIN... 235 AM CDT A CONTINUED TEXTBOOK SETUP FOR HEAVY RAIN REMAINS IN PLACE EARLY THIS MORNING AND WILL THROUGH LATE MORNING ACROSS THE FORECAST AREA...WITH SIGNIFICANT...EVEN RECORD RIVER FLOODING...A RESPONSE OVER THE NEXT COUPLE DAYS. WHILE AREAL FLOODING REPORTS HAVE BECOME A MORE FAR AND FEW BETWEEN VERY EARLY THIS MORNING...ONLY PART OF THAT IS LIKELY DUE TO A TEMPORARY EASE IN RAINFALL RATES AND MORE OF IT DUE TO THE FACT IT IS DARK OUTSIDE. RAINFALL AMOUNTS ESTIMATED BY RADAR OR OBSERVED THROUGH 1 AM THURSDAY ARE BETWEEN ONE AND A HALF TO FOUR INCHES....WITH THE HIGHEST AMOUNTS IN NORTHWEST LIVINGSTON COUNTY...THE PANHANDLE OF LASALLE COUNTY...AND WESTERN LEE AND OGLE COUNTIES. THE ELEVATED STATIONARY FRONT IS PARKED DIRECTLY OVER THE CWA WITH CONTINUOUS -70C CLOUD TOPS AND ASSOCIATED DEEP CONVECTION TRAINING ENE. IMPRESSIVE LOW-LEVEL CONVERGENCE IS FOCUSED ALONG THIS BOUNDARY AS JUST INFERRED BY THE VAD WIND PROFILER ANALYSIS EARLY THIS MORNING...WITH 70 KTS OF SOUTHERLY 850MB FLOW OVER LSX AND ILX...25 KTS AT LOT...AND NORTHERLY FLOW AT DVN AND MKX. THE REPLENISHMENT OF MOISTURE ON THIS LOW-LEVEL JET IS EXTREME...WITH MOISTURE TRANSPORT MAGNITUDES VERY HIGH. AMBIENT MOISTURE VALUES ARE ALSO PRACTICALLY OFF THE CHARTS...WITH PWAT VALUES RIGHT AT AND POSSIBLY OVER RECORD APRIL LEVELS BASED ON THE HISTORICAL RAOB RECORDS. A TONGUE OF 4C AND HIGHER DEW POINTS AT 700MB ON LAST EVES RAOBS AND CONTINUED TO BE ANALYZED ARE DIRECTED RIGHT INTO THE AREA...WHICH ARE AT LEVELS SHOWN TO REFLECT WARM SEASON RAIN PROCESSES. REFLECTIVITY SINCE MIDNIGHT HAS LOST SOME OF ITS ORGANIZED EMBEDDED STORMS...HOWEVER THE AMOUNT OF 40+ DBZ REMAINS HIGH ALONG WITH LIGHTNING...BOTH REFLECTIVE OF HEAVIER RAINFALL RATES. AGAIN...CONTENT/CONCENTRATION...REPLENISHMENT...AND FOCUS/POOLING OF HEAVY RAINFALL PARAMETERS ARE ALL IN PLACE. LOOKING FORWARD THROUGH 10 AM...THESE PARAMETERS ALMOST ENTIRELY REMAIN IN PLACE. WITH SIX HOUR FLOOD GUIDANCE BEING APPROACHED AND MORE OF THE WATER TURNING INTO RUNOFF IMMEDIATELY...THIS IS LIKELY IN ITSELF TO CAUSE FLOODING ISSUES. WHILE THE BOUNDARY HAS TRIED TO INCH NORTHWARD AND THAT HAS BEEN SEEN SLIGHTLY IN THE RAIN PLACEMENT...AN APPROACHING DEEP SHORT WAVE FROM WESTERN MO WILL LIKELY CONTINUE TO BLOSSOM CONVECTION ACROSS WESTERN IL INTO THE FORECAST AREA. SO AN UPTICK IN CONVECTION IS PROBABLE...AND THUS EVEN SOME HEAVIER RAINFALL RATES FOR A PERIOD. THIS IS MOST FAVORED SOUTH OF INTERSTATE 88 ON CONVECTIVE ALLOWING MODELS. HAVE GONE WITH FLOOD WARNINGS BUT FLASH FLOODING AS THIS PASSES ACROSS MAY BE SEEN...ESPECIALLY IN PARTS OF LA SALLE AND LIVINGSTON COUNTIES...AS WELL AS ANY URBAN AREAS IMPACTED. MTF && .DISCUSSION... 934 PM CDT EVENING/MESOSCALE UPDATE... HAVE CANCELLED REMAINING CONVECTIVE WATCHES...THOUGH FLOODING WILL CONTINUE TO BE A SIGNIFICANT ISSUE THROUGH THURSDAY AND BEYOND. WARM FRONT EXTENDS FROM LOW PRESSURE WAVE OVER WESTERN MISSOURI... NORTHEAST INTO CENTRAL ILLINOIS AND CENTRAL INDIANA AT 02Z. OUTFLOW FROM PERSISTENT ELEVATED THUNDERSTORMS ACROSS IA/NORTHERN IL/IN HAS CONTINUED TO SUPPRESS SURFACE WARM FRONT SOUTH OF THE CWA...AND WILL LIKELY CONTINUE TO DO SO OVERNIGHT BEFORE DEEPENING SURFACE LOW LIFTS FROM MISSOURI INTO NORTHWEST IL IN ASSOCIATION WITH SHORT WAVE LIFTING OUT OF BASE OF UPPER TROUGH OVER THE SOUTHERN PLAINS. UNFORTUNATELY...THIS WILL RESULT IN CONTINUED FORCED ASCENT ATOP CONVECTIVELY ENHANCED FRONTAL ZONE TONIGHT WITHIN A BROAD REGION OF PERSISTENT STRONG WARM/MOIST ADVECTION AHEAD OF DEEP UPPER TROUGH OVER THE PLAINS. ILX 00Z SOUNDING TELLS THE STORY WITH RESPECT TO THE DIMINISHED SEVERE THREAT WITH STRONG LOW LEVEL INVERSION NORTH OF FRONT PREVENTING NEAR SFC-BASED STORMS. RAP GUIDANCE CONTINUES TO DEPICT A GRADIENT IN THE MUCAPE FIELD INCREASING TO 500-1000 J/KG AS YOU MOVE FARTHER SOUTH OF I-80. WHILE EFFECTIVE BULK SHEAR IN EXCESS OF 60 KT WILL CONTINUE TO ALLOW SOME ORGANIZATION FOR ELEVATED CONVECTION NORTH OF WARM FRONT...THE THREAT OF SEVERE WEATHER SHOULD BE LIMITED TO MARGINAL HAIL WITH THE BETTER ORGANIZED STORMS. WHILE THE SEVERE THREAT INTO THE OVERNIGHT HOURS IS RATHER LOW... FLOODING THREAT CONTINUES TO BE SIGNIFICANT INTO THURSDAY. RADAR ESTIMATES AND OBSERVED RAINFALL REPORTS INDICATE THAT MOST AREAS HAVE SEEN UPWARDS OF 0.75 INCHES OF RAIN...WITH MANY AREAS BETWEEN 1.5 AND 2.0 INCHES AND PARTS OF NORTH CENTRAL ILLINOIS IN EXCESS OF 2.5 INCHES. ILX 00Z RAOB DEPICTS PWAT OF 1.38 INCHES...199 PERCENT OF NORMAL...AN INDICATION OF THE VERY MOIST AIR MASS. ADDITIONAL RAINFALL AMOUNTS IN THE 1-2 INCH RANGE ARE VERY LIKELY THROUGH THURSDAY...LIKELY LEADING TO EXTENSIVE FLOODING ON AREA STREAMS AND RIVERS. AERIAL FLOOD WARNINGS REMAIN IN EFFECT INTO MIDDAY THURSDAY...AND MANY RIVER FORECAST SITES ARE HEADED FOR MODERATE TO MAJOR FLOODING. RATZER //PREV DISCUSSION... 342 PM CDT .SHORT TERM...THROUGH FRIDAY... HAZARDOUS WEATHER ISSUES FROM SEVERE THUNDERSTORMS TO EXCESSIVE RAINFALL TO TORNADIC POTENTIAL WILL IMPACT THE REGION THROUGH THURSDAY NIGHT. FOR THE REMAINDER OF THE AFTERNOON AND INTO THIS EVENING...AT 230PM CDT...STRONG THUNDERSTORMS EXTEND ALONG A LINE FROM NEAR WAUKEGAN...SOUTHWEST THROUGH OTTAWA. WEST OF THIS LINE...AN EXTENSIVE AREA OF OVERRUNNING PCPN WITH EMBEDDED THUNDER EXTENDED BACK THROUGH ERN IOWA AND MISSOURI. MUCH OF THE ACTIVITY OVER NRN IL HAS FORMED ALONG AN ELEVATED WARM FRONT...BUT A MORE SOLID LINE HAS DEVELOPED IN THE WARM SECTOR. EXPECT THAT THE THUNDERSTORMS WILL SAG SEWD THROUGH THE EVENING...BRINGING SHOWERS AND THUNDERSTORMS INTO EAST-CENTRAL ILLINOIS AND NORTHWESTERN INDIANA. WITH COPIOUS AMOUNTS OF MOISTURE STREAMING INTO THE REGION...THE STORMS HAVE BEEN VERY EFFICIENT RAIN PRODUCERS...WITH 0.81 INCHES OF RAIN MEASURED AT THE ROCKFORD AIRPORT BTWN 12-18Z THIS MORNING. STORMS HAVE ALSO BEEN MARGINALLY SEVERE WITH NUMEROUS REPORTS OF SMALL HAIL RECEIVED...AND A FEW REPORTS OF LARGER HAIL AS WELL. THIS WILL BE THE CONVECTIVE MODE FOR THE REMAINDER OF THE EVENING AND OVERNIGHT TONIGHT...WITH MODERATE TO HEAVY RAIN AND SMALL HAIL AND OCCASIONAL STRONG WINDS GUSTS. THE FLOODING AND SEVERE WEATHER POTENTIAL WILL RAMP UP EVEN FURTHER TOMORROW AS THE UPPER TROUGH MOVES OUT OVER THE CENTRAL PLAINS AND A SFC LOW DEEPENS. THE SFC LOW WILL SWING THROUGH THE SOUTH HIGH PLAINS EARLY THIS EVENING BEFORE TURNING NEWD...RIPPLING ALONG A QUASI-STATIONARY COLD FRONT AND WARM FRONT. BY THURSDAY MORNING...THE LOW WILL ELONGATE FROM NWRN IL THROUGH NWRN MO...WITH THE SFC WARM FRONT EXTENDING NEWD ACROSS CENTRAL LAKE MICHIGAN. THIS WILL PUT THE CWA FIRMLY IN THE WARM SECTOR. WITH A WIDE OPEN GLFMEX...DEEP LAYER MOISTURE WILL STREAM NWD INTO THE REGION...WITH PWATS EXCEEDING 1.5 INCHES FOR AN EXTENDED PERIOD OF TIME...LEADING TO THE POTENTIAL FOR SIGNIFICANT WIDESPREAD RIVER AND AREAL FLOODING. SEE THE HYDROLOGY SECTION FOR FURTHER DETAILS. THE SEVERE WEATHER MODE SHOULD FOCUS ON STRONG...DAMAGING WINDS AND POSSIBLE TORNADOES. THE LATEST SPC DAY 2 CONVECTIVE OUTLOOK HAS INCREASED THE AREA SOUTH OF A LINE FROM EVANSTON TO PONTIAC TO A MODERATE RISK...WITH THE REMAINDER OF THE AREA IN A SLIGHT RISK. INCREASING HEAT AND MOISTURE...TEMPERATURES REACHING INTO THE LOW TO MIDDLE 70S AND DEW POINTS IN THE LOW TO MIDDLE 60S IN THE WARM SECTOR...INSTABILITY WILL BE AMPLE. WHILE THE GENERAL CONVECTIVE MODE WILL BE LINEAR WITH SMALL LINES AND BOWS POSSIBLE...PRODUCING DAMAGING WINDS...THE MODEL GUIDANCE IS IN GOOD AGREEMENT ON A STRONG LOW LEVEL JET...WITH SWLY WINDS OF 55-65KT ACROSS THE REGION. WHILE SFC WINDS ARE GENERALLY PROGGED TO BE SOUTHERLY...THERE WILL BE OPPORTUNITY FOR SFC WINDS TO BACK A LITTLE MORE EAST OF SOUTH AS THE SFC LOW TRACKS THROUGH NWRN IL AND INTO SRN WI. GIVEN THE AMPLE INSTABILITY...COMBINED WITH CLOCKWISE TURNING HODOGRAPHS...DISCRETE SUPER CELLS MAY DEVELOP OUT IN THE WARM SECTOR AHEAD OF THE LINEAR CONVECTION...WHICH WOULD BRING THE TORNADIC POTENTIAL TO THE REGION. THE POTENTIAL FOR SEVERE WEATHER AND HEAVY RAINFALL WILL CONTINUE UNTIL THE ASSOCIATED COLD FRONT PUSHES THROUGH THE REGION...BRINGING IN MUCH COOLER AIR. THE GUIDANCE IS IN GOOD AGREEMENT ON PUSHING THE FRONT ACROSS THE AREA THURSDAY EVENING. AS THE SFC LOW PUSHES OFF TO THE NORTHEAST...THE UPPER TROUGH WILL ALSO CROSS THE AREA. WITH PLENTY OF RESIDUAL SFC MOISTURE AND COOLER AIR AND CYCLONIC CURVATURE ALOFT...SOME LINGERING INSTABILITY SHOWERS SHOULD PERSIST INTO FRIDAY. HIGHS ON FRIDAY SHOULD DROP BACK INTO THE MIDDLE TO UPPER 40S. KREIN .LONG TERM - SATURDAY THROUGH WEDNESDAY... SPRAWLING SURFACE HIGH PRESSURE TO BUILD INTO THE AREA SATURDAY BEHIND DEPARTING SURFACE LOW/UPPER LEVEL TROUGH. A RETURN TO UNSEASONABLY COOL TEMPS WITH A NEEDED BREAK IN PRECIPITATION WILL BE SHORT LIVED HOWEVER AS THE UPPER FLOW QUICKLY RETURNS SOUTHWESTERLY AS ANOTHER POWERFUL SHORTWAVE TROUGH DIGS INTO WESTERN NORTH AMERICA ON SUNDAY. THIS SHORTWAVE CARVES OUT A TROUGH ACROSS THE MOUNTAIN WEST SUNDAY NIGHT INTO MONDAY. A SERIES OF UPPER LEVEL SHORT WAVE TROUGHS WILL THEN RIPPLE NORTHEAST IN THE SW FLOW ALOFT. SPECIFIC FEATURES ARE POORLY RESOLVED BY MEDIUM RANGE MODELS BUT OVERALL TREND WILL BE A RETURN TO INCREASING MOISTURE AS GULF OPENS BACK UP AGAIN. MEDIUM RANGE MODELS ARE IN FAIRLY GOOD AGREEMENT IN CONCEPT IN SAGGING THE SURFACE FRONTAL BOUNDARY SOUTH ACROSS THE LOCAL AREA MONDAY NIGHT AND STALLING IT OUT TUESDAY SETTING THE STAGE FOR ANOTHER PROLONGED PERIOD OF WET WEATHER TUESDAY INTO WEDNESDAY AS RIPPLES OF LOW PRESSURE LIFT NORTHEAST ALONG THE BOUNDARY. EF && .HYDROLOGY... 350 PM CDT WITH SFC DEW POINTS EXPECTED TO REACH INTO THE LOWER TO MIDDLE 60S AND PWATS POSSIBLY REACHING AS HIGH AS 1.75 INCHES...ANY THUNDERSTORMS THAT DEVELOP WILL BE EFFICIENT RAIN PRODUCERS. BASED ON THE MATT BUNKERS PWAT CLIMATOLOGY...THESE VALUES APPROACH RECORD LEVELS. SO...FLOODING WILL BE A MAJOR CONCERN FOR THE ENTIRE CWA...WITH STORM TOTAL PCPN AMOUNTS OF 2-3 INCHES OVER THE SERN PORTIONS OF THE CWA...GENERALLY SOUTH OF I-80...AND 3-4 INCHES TO THE NORTH. LATEST LOCAL QPF WOULD SUGGEST AN AREA OF PCPN OF 4-5 INCHES IS POSSIBLE ALONG OVER NORTHERN ILLINOIS. THIS REPRESENTS AN INCREASE OVER PREVIOUS FORECASTS...BUT GIVEN THE RECORD LEVEL PWATS FOR AN EXTENDED PERIOD OF TIME...CONFIDENCE IS INCREASING FOR THIS SIGNIFICANT RAINFALL. WITH MANY RIVERS AND STREAMS ARE ALREADY NEAR OR ABOVE MINOR FLOOD STAGE...THIS AMOUNT OF RAIN WILL BRING ADDITIONAL RISES TO MODERATE AND MAJOR FLOOD LEVEL. IN ADDITION TO RIVER FLOODING...AREAL FLOODING OR RURAL...SUBURBAN AND URBAN AREAS IS LIKELY...WITH LOW LYING ROADS AND VIADUCTS FLOODING...AS WELL AS...ROADSIDE DRAINAGE DITCHES AND DRAINAGE PONDS EXCEEDING CAPACITY. AREAS NOT SEEING FLOODING WILL AT LEAST SEE AREAS OF STANDING OR PONDING WATER ON ROADS. KREIN && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 06Z... * WIDESPREAD SHRA AND TS TONIGHT. * PERIODS OF VERY HEAVY RAINFALL THROUGH THE PERIOD...WITH LOW VIS UNDER 2 MILES AT TIMES. * LOW LEVEL WIND SHEAR THIS EARLY THIS MORNING WITH A 50 KT SOUTHERLY JET AT 2,000 FT AGL. * WINDS SHIFTING OUT OF THE SOUTH AFTER 10 UTC WITH WINDS LIKELY GUSTING TO 30 TO 35 KT AT TIMES THROUGH MUCH OF THE DAY. * TIMING OF IMPROVING CONDITIONS BY THIS EVENING. KJB //DISCUSSION...UPDATED 06Z... SHOWERS AND THUNDERSTORMS WILL CONTINUE TO TRAIN NORTHEASTWARD FROM MISSOURI ACROSS NORTHERN ILLINOIS OVERNIGHT TONIGHT. MOISTURE TRANSPORT IS ABSOLUTELY IMPRESSIVE...WITH A 50 TO 60KT LOW LEVEL JET CONTINUALLY PUMPING IN DEEPER MOISTURE. PRECIPITABLE WATER VALUES ARE PROGGED TO INCREASE TO NEAR 1.6 INCHES WHICH IS NEAR RECORD VALUES FOR THIS TIME OF YEAR. THE COMBINATION OF THIS DEEP MOISTURE AND THE THE STRONG DYNAMIC FORCING FROM THIS SYSTEM WILL CONTINUE TO SUPPORT CONVECTIVE ACTIVITY. THERE COULD BE A VERY SHORT BREAK IN THE ACTIVITY AROUND DAYBREAK AT THE EASTERN TERMINALS AS THE WARM FRONT SURGES NORTHWARD THROUGH THE NIGHT. HOWEVER...CONFIDENCE IN THIS IS LOW. ANY BREAK IN THE ACTIVITY...WOULD BE SHORT LIVED...AS ADDITIONAL THUNDERSTORMS WILL MAKE A RETURN BY MID TO LATE MORNING. VERY HEAVY RAINFALL WILL LIKELY ACCOMPANY THESE THUNDERSTORMS. IT ALSO APPEARS THAT SEVERAL HOURS OF ADDITIONAL THUNDERSTORM ACTIVITY IS LIKELY FROM MID TO LATE MORNING THROUGH MUCH OF THE AFTERNOON AS THE CLOUD BEARING FLOW LOOKS TO REMAIN PARALLEL TO THE APPROACHING SURFACE BOUNDARY...WHICH SHOULD RESULT IN TRAINING CELLS. THIS HEAVY RAIN WILL LIKELY REDUCE VISIBILITY UNDER 2 SM AT TIMES...ESPECIALLY DURING THE AFTERNOON. WINDS WILL RAPIDLY INCREASE OUT OF THE SOUTH BY EARLY MORNING AS THE WARM FRONT LIFTS NORTH OF THE AREA. DUE TO THE PRESENCE OF 50 KT OF FLOW ONLY A COUPLE THOUSAND FEET OFF THE GROUND...SOME OF THIS MOMENTUM WILL LIKELY BE MIXED TO THE SURFACE. THUS WINDS WILL LIKELY GUST IN THE LOW TO MID 30 KT RANGE FOR MUCH OF THE DAY. EVEN HIGH WINDS WILL BE POSSIBLE IN WITHIN THE STRONGER STORMS. THUNDERSTORM ACTIVITY SHOULD BEGIN TO ABATE ACROSS THE AREA BY LATE AFTERNOON OR EARLY IN THE EVENING. HOWEVER...THE WINDS WILL SHIFT OUT OF THE WEST SOUTHWEST BEHIND A COLD FRONT BY MID EVENING. THE WINDS WILL LIKELY REMAIN GUSTY UP AROUND 30 KT BEHIND THIS FRONT...BUT THE THREAT FOR THUNDER SHOULD END. KJB //ORD AND MDW CONFIDENCE...UPDATED 06Z... HIGH CONFIDENCE IN PERIODS OF HEAVY THUNDERSTORM RAIN. LOW TO MEDIUM CONFIDENCE ON TIMING OF IMPROVING CONDITIONS LATER TODAY. MODERATE TO HIGH CONFIDENCE IN WINDS. HIGH CONFIDENCE IN IFR AND LOWER VIS AND CIGS IN +TSRA ACTIVITY. KJB //OUTLOOK FOR ORD/MDW FOR 12Z FRIDAY-12Z WEDNESDAY...UPDATED 00Z... FRIDAY...VFR...CHANCE SHRA WITH LOCAL MVFR. SATURDAY...VFR...LAKE BREEZE DEVELOPING AND REACHING CHI TERMINALS EARLY-MID AFTERNOON. SUNDAY...VFR...SLIGHT CHANCE SHRA. MONDAY...VFR...CHANCE SHOWERS. TUESDAY...MVFR LOWERING TO IFR....CHANCE OF SHOWERS. TRS && .MARINE... 420 PM CDT A PAIR OF LOW PRESSURE CENTERS OVER NORTHERN MISSOURI AND THE TEXAS PANHANDLE WILL MOVE NORTHEAST TONIGHT AND THURSDAY AND OVERSPREAD THE GREAT LAKES AREA. A BRIEF PERIOD OF OCCASIONALLY GALE FORCE GUSTS WILL OCCUR ACROSS SOUTHERN LAKE MICHIGAN THURSDAY AS THE SURFACE PRESSURE GRADIENT INTENSIFIES SOUTH OF THE ELONGATED LOW PRESSURE AREA FROM THE SAULT TO GREEN BAY. AS LOW PRESSURE LOCATES NEAR MILWAUKEE THURSDAY EVENING AND THEN MOVES NORTHEAST TO THE STRAITS OF MACKINAC BY DAYBREAK FRIDAY... A POWERFUL COLD FRONT WILL SURGE EAST ACROSS THE LAKE WITH WINDS INCREASING RAPIDLY BEHIND THE FRONT DURING THE PREDAWN HOURS FRIDAY. WINDS WILL RAPIDLY REACH GALE FORCE TO 45 KTS FRIDAY WITH A DIMINISHING TREND BEGINNING AFTER DARK FRIDAY EVENING. SURFACE HIGH PRESSURE WILL BUILD INTO THE AREA SATURDAY BRINGING A PERIOD OF LIGHT WINDS LASTING ONLY UNTIL DAYBREAK SUNDAY WHEN SOUTHERLY FLOW WILL AGAIN INCREASE AHEAD OF AN APPROACHING FRONTAL BOUNDARY. ED F && .LOT WATCHES/WARNINGS/ADVISORIES... IL...FLOOD WATCH...ILZ003-ILZ004-ILZ005-ILZ006-ILZ008-ILZ010-ILZ011- ILZ012-ILZ013-ILZ014-ILZ019-ILZ020-ILZ021-ILZ022-ILZ023- ILZ032-ILZ033-ILZ039 UNTIL 7 AM FRIDAY. IN...FLOOD WATCH...INZ001-INZ002-INZ010-INZ011-INZ019 UNTIL 7 AM FRIDAY. LM...GALE WATCH...LMZ080-LMZ261-LMZ362-LMZ364-LMZ366-LMZ563-LMZ565- LMZ567-LMZ669-LMZ671-LMZ673-LMZ675-LMZ777-LMZ779-LMZ868- LMZ870-LMZ872-LMZ874-LMZ876-LMZ878...7 AM FRIDAY TO 4 AM SATURDAY. GALE WARNING...LMZ740-LMZ741-LMZ742...7 AM THURSDAY TO 7 PM THURSDAY. SMALL CRAFT ADVISORY...NEARSHORE WATERS UNTIL 7 AM THURSDAY. GALE WARNING...LMZ743-LMZ744-LMZ745...7 AM THURSDAY TO 10 PM THURSDAY. && $$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
124 AM CDT THU APR 18 2013 .DISCUSSION... 934 PM CDT EVENING/MESOSCALE UPDATE... HAVE CANCELLED REMAINING CONVECTIVE WATCHES...THOUGH FLOODING WILL CONTINUE TO BE A SIGNIFICANT ISSUE THROUGH THURSDAY AND BEYOND. WARM FRONT EXTENDS FROM LOW PRESSURE WAVE OVER WESTERN MISSOURI... NORTHEAST INTO CENTRAL ILLINOIS AND CENTRAL INDIANA AT 02Z. OUTFLOW FROM PERSISTENT ELEVATED THUNDERSTORMS ACROSS IA/NORTHERN IL/IN HAS CONTINUED TO SUPPRESS SURFACE WARM FRONT SOUTH OF THE CWA...AND WILL LIKELY CONTINUE TO DO SO OVERNIGHT BEFORE DEEPENING SURFACE LOW LIFTS FROM MISSOURI INTO NORTHWEST IL IN ASSOCIATION WITH SHORT WAVE LIFTING OUT OF BASE OF UPPER TROUGH OVER THE SOUTHERN PLAINS. UNFORTUNATELY...THIS WILL RESULT IN CONTINUED FORCED ASCENT ATOP CONVECTIVELY ENHANCED FRONTAL ZONE TONIGHT WITHIN A BROAD REGION OF PERSISTENT STRONG WARM/MOIST ADVECTION AHEAD OF DEEP UPPER TROUGH OVER THE PLAINS. ILX 00Z SOUNDING TELLS THE STORY WITH RESPECT TO THE DIMINISHED SEVERE THREAT WITH STRONG LOW LEVEL INVERSION NORTH OF FRONT PREVENTING NEAR SFC-BASED STORMS. RAP GUIDANCE CONTINUES TO DEPICT A GRADIENT IN THE MUCAPE FIELD INCREASING TO 500-1000 J/KG AS YOU MOVE FARTHER SOUTH OF I-80. WHILE EFFECTIVE BULK SHEAR IN EXCESS OF 60 KT WILL CONTINUE TO ALLOW SOME ORGANIZATION FOR ELEVATED CONVECTION NORTH OF WARM FRONT...THE THREAT OF SEVERE WEATHER SHOULD BE LIMITED TO MARGINAL HAIL WITH THE BETTER ORGANIZED STORMS. WHILE THE SEVERE THREAT INTO THE OVERNIGHT HOURS IS RATHER LOW... FLOODING THREAT CONTINUES TO BE SIGNIFICANT INTO THURSDAY. RADAR ESTIMATES AND OBSERVED RAINFALL REPORTS INDICATE THAT MOST AREAS HAVE SEEN UPWARDS OF 0.75 INCHES OF RAIN...WITH MANY AREAS BETWEEN 1.5 AND 2.0 INCHES AND PARTS OF NORTH CENTRAL ILLINOIS IN EXCESS OF 2.5 INCHES. ILX 00Z RAOB DEPICTS PWAT OF 1.38 INCHES...199 PERCENT OF NORMAL...AN INDICATION OF THE VERY MOIST AIR MASS. ADDITIONAL RAINFALL AMOUNTS IN THE 1-2 INCH RANGE ARE VERY LIKELY THROUGH THURSDAY...LIKELY LEADING TO EXTENSIVE FLOODING ON AREA STREAMS AND RIVERS. AERIAL FLOOD WARNINGS REMAIN IN EFFECT INTO MIDDAY THURSDAY...AND MANY RIVER FORECAST SITES ARE HEADED FOR MODERATE TO MAJOR FLOODING. RATZER //PREV DISCUSSION... 342 PM CDT .SHORT TERM...THROUGH FRIDAY... HAZARDOUS WEATHER ISSUES FROM SEVERE THUNDERSTORMS TO EXCESSIVE RAINFALL TO TORNADIC POTENTIAL WILL IMPACT THE REGION THROUGH THURSDAY NIGHT. FOR THE REMAINDER OF THE AFTERNOON AND INTO THIS EVENING...AT 230PM CDT...STRONG THUNDERSTORMS EXTEND ALONG A LINE FROM NEAR WAUKEGAN...SOUTHWEST THROUGH OTTAWA. WEST OF THIS LINE...AN EXTENSIVE AREA OF OVERRUNNING PCPN WITH EMBEDDED THUNDER EXTENDED BACK THROUGH ERN IOWA AND MISSOURI. MUCH OF THE ACTIVITY OVER NRN IL HAS FORMED ALONG AN ELEVATED WARM FRONT...BUT A MORE SOLID LINE HAS DEVELOPED IN THE WARM SECTOR. EXPECT THAT THE THUNDERSTORMS WILL SAG SEWD THROUGH THE EVENING...BRINGING SHOWERS AND THUNDERSTORMS INTO EAST-CENTRAL ILLINOIS AND NORTHWESTERN INDIANA. WITH COPIOUS AMOUNTS OF MOISTURE STREAMING INTO THE REGION...THE STORMS HAVE BEEN VERY EFFICIENT RAIN PRODUCERS...WITH 0.81 INCHES OF RAIN MEASURED AT THE ROCKFORD AIRPORT BTWN 12-18Z THIS MORNING. STORMS HAVE ALSO BEEN MARGINALLY SEVERE WITH NUMEROUS REPORTS OF SMALL HAIL RECEIVED...AND A FEW REPORTS OF LARGER HAIL AS WELL. THIS WILL BE THE CONVECTIVE MODE FOR THE REMAINDER OF THE EVENING AND OVERNIGHT TONIGHT...WITH MODERATE TO HEAVY RAIN AND SMALL HAIL AND OCCASIONAL STRONG WINDS GUSTS. THE FLOODING AND SEVERE WEATHER POTENTIAL WILL RAMP UP EVEN FURTHER TOMORROW AS THE UPPER TROUGH MOVES OUT OVER THE CENTRAL PLAINS AND A SFC LOW DEEPENS. THE SFC LOW WILL SWING THROUGH THE SOUTH HIGH PLAINS EARLY THIS EVENING BEFORE TURNING NEWD...RIPPLING ALONG A QUASI-STATIONARY COLD FRONT AND WARM FRONT. BY THURSDAY MORNING...THE LOW WILL ELONGATE FROM NWRN IL THROUGH NWRN MO...WITH THE SFC WARM FRONT EXTENDING NEWD ACROSS CENTRAL LAKE MICHIGAN. THIS WILL PUT THE CWA FIRMLY IN THE WARM SECTOR. WITH A WIDE OPEN GLFMEX...DEEP LAYER MOISTURE WILL STREAM NWD INTO THE REGION...WITH PWATS EXCEEDING 1.5 INCHES FOR AN EXTENDED PERIOD OF TIME...LEADING TO THE POTENTIAL FOR SIGNIFICANT WIDESPREAD RIVER AND AREAL FLOODING. SEE THE HYDROLOGY SECTION FOR FURTHER DETAILS. THE SEVERE WEATHER MODE SHOULD FOCUS ON STRONG...DAMAGING WINDS AND POSSIBLE TORNADOES. THE LATEST SPC DAY 2 CONVECTIVE OUTLOOK HAS INCREASED THE AREA SOUTH OF A LINE FROM EVANSTON TO PONTIAC TO A MODERATE RISK...WITH THE REMAINDER OF THE AREA IN A SLIGHT RISK. INCREASING HEAT AND MOISTURE...TEMPERATURES REACHING INTO THE LOW TO MIDDLE 70S AND DEW POINTS IN THE LOW TO MIDDLE 60S IN THE WARM SECTOR...INSTABILITY WILL BE AMPLE. WHILE THE GENERAL CONVECTIVE MODE WILL BE LINEAR WITH SMALL LINES AND BOWS POSSIBLE...PRODUCING DAMAGING WINDS...THE MODEL GUIDANCE IS IN GOOD AGREEMENT ON A STRONG LOW LEVEL JET...WITH SWLY WINDS OF 55-65KT ACROSS THE REGION. WHILE SFC WINDS ARE GENERALLY PROGGED TO BE SOUTHERLY...THERE WILL BE OPPORTUNITY FOR SFC WINDS TO BACK A LITTLE MORE EAST OF SOUTH AS THE SFC LOW TRACKS THROUGH NWRN IL AND INTO SRN WI. GIVEN THE AMPLE INSTABILITY...COMBINED WITH CLOCKWISE TURNING HODOGRAPHS...DISCRETE SUPER CELLS MAY DEVELOP OUT IN THE WARM SECTOR AHEAD OF THE LINEAR CONVECTION...WHICH WOULD BRING THE TORNADIC POTENTIAL TO THE REGION. THE POTENTIAL FOR SEVERE WEATHER AND HEAVY RAINFALL WILL CONTINUE UNTIL THE ASSOCIATED COLD FRONT PUSHES THROUGH THE REGION...BRINGING IN MUCH COOLER AIR. THE GUIDANCE IS IN GOOD AGREEMENT ON PUSHING THE FRONT ACROSS THE AREA THURSDAY EVENING. AS THE SFC LOW PUSHES OFF TO THE NORTHEAST...THE UPPER TROUGH WILL ALSO CROSS THE AREA. WITH PLENTY OF RESIDUAL SFC MOISTURE AND COOLER AIR AND CYCLONIC CURVATURE ALOFT...SOME LINGERING INSTABILITY SHOWERS SHOULD PERSIST INTO FRIDAY. HIGHS ON FRIDAY SHOULD DROP BACK INTO THE MIDDLE TO UPPER 40S. KREIN .LONG TERM - SATURDAY THROUGH WEDNESDAY... SPRAWLING SURFACE HIGH PRESSURE TO BUILD INTO THE AREA SATURDAY BEHIND DEPARTING SURFACE LOW/UPPER LEVEL TROUGH. A RETURN TO UNSEASONABLY COOL TEMPS WITH A NEEDED BREAK IN PRECIPITATION WILL BE SHORT LIVED HOWEVER AS THE UPPER FLOW QUICKLY RETURNS SOUTHWESTERLY AS ANOTHER POWERFUL SHORTWAVE TROUGH DIGS INTO WESTERN NORTH AMERICA ON SUNDAY. THIS SHORTWAVE CARVES OUT A TROUGH ACROSS THE MOUNTAIN WEST SUNDAY NIGHT INTO MONDAY. A SERIES OF UPPER LEVEL SHORT WAVE TROUGHS WILL THEN RIPPLE NORTHEAST IN THE SW FLOW ALOFT. SPECIFIC FEATURES ARE POORLY RESOLVED BY MEDIUM RANGE MODELS BUT OVERALL TREND WILL BE A RETURN TO INCREASING MOISTURE AS GULF OPENS BACK UP AGAIN. MEDIUM RANGE MODELS ARE IN FAIRLY GOOD AGREEMENT IN CONCEPT IN SAGGING THE SURFACE FRONTAL BOUNDARY SOUTH ACROSS THE LOCAL AREA MONDAY NIGHT AND STALLING IT OUT TUESDAY SETTING THE STAGE FOR ANOTHER PROLONGED PERIOD OF WET WEATHER TUESDAY INTO WEDNESDAY AS RIPPLES OF LOW PRESSURE LIFT NORTHEAST ALONG THE BOUNDARY. EF && .HYDROLOGY... 350 PM CDT WITH SFC DEW POINTS EXPECTED TO REACH INTO THE LOWER TO MIDDLE 60S AND PWATS POSSIBLY REACHING AS HIGH AS 1.75 INCHES...ANY THUNDERSTORMS THAT DEVELOP WILL BE EFFICIENT RAIN PRODUCERS. BASED ON THE MATT BUNKERS PWAT CLIMATOLOGY...THESE VALUES APPROACH RECORD LEVELS. SO...FLOODING WILL BE A MAJOR CONCERN FOR THE ENTIRE CWA...WITH STORM TOTAL PCPN AMOUNTS OF 2-3 INCHES OVER THE SERN PORTIONS OF THE CWA...GENERALLY SOUTH OF I-80...AND 3-4 INCHES TO THE NORTH. LATEST LOCAL QPF WOULD SUGGEST AN AREA OF PCPN OF 4-5 INCHES IS POSSIBLE ALONG OVER NORTHERN ILLINOIS. THIS REPRESENTS AN INCREASE OVER PREVIOUS FORECASTS...BUT GIVEN THE RECORD LEVEL PWATS FOR AN EXTENDED PERIOD OF TIME...CONFIDENCE IS INCREASING FOR THIS SIGNIFICANT RAINFALL. WITH MANY RIVERS AND STREAMS ARE ALREADY NEAR OR ABOVE MINOR FLOOD STAGE...THIS AMOUNT OF RAIN WILL BRING ADDITIONAL RISES TO MODERATE AND MAJOR FLOOD LEVEL. IN ADDITION TO RIVER FLOODING...AREAL FLOODING OR RURAL...SUBURBAN AND URBAN AREAS IS LIKELY...WITH LOW LYING ROADS AND VIADUCTS FLOODING...AS WELL AS...ROADSIDE DRAINAGE DITCHES AND DRAINAGE PONDS EXCEEDING CAPACITY. AREAS NOT SEEING FLOODING WILL AT LEAST SEE AREAS OF STANDING OR PONDING WATER ON ROADS. KREIN && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 06Z... * WIDESPREAD SHRA AND TS TONIGHT. * PERIODS OF VERY HEAVY RAINFALL THROUGH THE PERIOD...WITH LOW VIS UNDER 2 MILES AT TIMES. * LOW LEVEL WIND SHEAR THIS EARLY THIS MORNING WITH A 50 KT SOUTHERLY JET AT 2,000 FT AGL. * WINDS SHIFTING OUT OF THE SOUTH AFTER 10 UTC WITH WINDS LIKELY GUSTING TO 30 TO 35 KT AT TIMES THROUGH MUCH OF THE DAY. * TIMING OF IMPROVING CONDITIONS BY THIS EVENING. KJB //DISCUSSION...UPDATED 06Z... SHOWERS AND THUNDERSTORMS WILL CONTINUE TO TRAIN NORTHEASTWARD FROM MISSOURI ACROSS NORTHERN ILLINOIS OVERNIGHT TONIGHT. MOISTURE TRANSPORT IS ABSOLUTELY IMPRESSIVE...WITH A 50 TO 60KT LOW LEVEL JET CONTINUALLY PUMPING IN DEEPER MOISTURE. PRECIPITABLE WATER VALUES ARE PROGGED TO INCREASE TO NEAR 1.6 INCHES WHICH IS NEAR RECORD VALUES FOR THIS TIME OF YEAR. THE COMBINATION OF THIS DEEP MOISTURE AND THE THE STRONG DYNAMIC FORCING FROM THIS SYSTEM WILL CONTINUE TO SUPPORT CONVECTIVE ACTIVITY. THERE COULD BE A VERY SHORT BREAK IN THE ACTIVITY AROUND DAYBREAK AT THE EASTERN TERMINALS AS THE WARM FRONT SURGES NORTHWARD THROUGH THE NIGHT. HOWEVER...CONFIDENCE IN THIS IS LOW. ANY BREAK IN THE ACTIVITY...WOULD BE SHORT LIVED...AS ADDITIONAL THUNDERSTORMS WILL MAKE A RETURN BY MID TO LATE MORNING. VERY HEAVY RAINFALL WILL LIKELY ACCOMPANY THESE THUNDERSTORMS. IT ALSO APPEARS THAT SEVERAL HOURS OF ADDITIONAL THUNDERSTORM ACTIVITY IS LIKELY FROM MID TO LATE MORNING THROUGH MUCH OF THE AFTERNOON AS THE CLOUD BEARING FLOW LOOKS TO REMAIN PARALLEL TO THE APPROACHING SURFACE BOUNDARY...WHICH SHOULD RESULT IN TRAINING CELLS. THIS HEAVY RAIN WILL LIKELY REDUCE VISIBILITY UNDER 2 SM AT TIMES...ESPECIALLY DURING THE AFTERNOON. WINDS WILL RAPIDLY INCREASE OUT OF THE SOUTH BY EARLY MORNING AS THE WARM FRONT LIFTS NORTH OF THE AREA. DUE TO THE PRESENCE OF 50 KT OF FLOW ONLY A COUPLE THOUSAND FEET OFF THE GROUND...SOME OF THIS MOMENTUM WILL LIKELY BE MIXED TO THE SURFACE. THUS WINDS WILL LIKELY GUST IN THE LOW TO MID 30 KT RANGE FOR MUCH OF THE DAY. EVEN HIGH WINDS WILL BE POSSIBLE IN WITHIN THE STRONGER STORMS. THUNDERSTORM ACTIVITY SHOULD BEGIN TO ABATE ACROSS THE AREA BY LATE AFTERNOON OR EARLY IN THE EVENING. HOWEVER...THE WINDS WILL SHIFT OUT OF THE WEST SOUTHWEST BEHIND A COLD FRONT BY MID EVENING. THE WINDS WILL LIKELY REMAIN GUSTY UP AROUND 30 KT BEHIND THIS FRONT...BUT THE THREAT FOR THUNDER SHOULD END. KJB //ORD AND MDW CONFIDENCE...UPDATED 06Z... HIGH CONFIDENCE IN PERIODS OF HEAVY THUNDERSTORM RAIN. LOW TO MEDIUM CONFIDENCE ON TIMING OF IMPROVING CONDITIONS LATER TODAY. MODERATE TO HIGH CONFIDENCE IN WINDS. HIGH CONFIDENCE IN IFR AND LOWER VIS AND CIGS IN +TSRA ACTIVITY. KJB //OUTLOOK FOR ORD/MDW FOR 12Z FRIDAY-12Z WEDNESDAY...UPDATED 00Z... FRIDAY...VFR...CHANCE SHRA WITH LOCAL MVFR. SATURDAY...VFR...LAKE BREEZE DEVELOPING AND REACHING CHI TERMINALS EARLY-MID AFTERNOON. SUNDAY...VFR...SLIGHT CHANCE SHRA. MONDAY...VFR...CHANCE SHOWERS. TUESDAY...MVFR LOWERING TO IFR....CHANCE OF SHOWERS. TRS && .MARINE... 420 PM CDT A PAIR OF LOW PRESSURE CENTERS OVER NORTHERN MISSOURI AND THE TEXAS PANHANDLE WILL MOVE NORTHEAST TONIGHT AND THURSDAY AND OVERSPREAD THE GREAT LAKES AREA. A BRIEF PERIOD OF OCCASIONALLY GALE FORCE GUSTS WILL OCCUR ACROSS SOUTHERN LAKE MICHIGAN THURSDAY AS THE SURFACE PRESSURE GRADIENT INTENSIFIES SOUTH OF THE ELONGATED LOW PRESSURE AREA FROM THE SAULT TO GREEN BAY. AS LOW PRESSURE LOCATES NEAR MILWAUKEE THURSDAY EVENING AND THEN MOVES NORTHEAST TO THE STRAITS OF MACKINAC BY DAYBREAK FRIDAY... A POWERFUL COLD FRONT WILL SURGE EAST ACROSS THE LAKE WITH WINDS INCREASING RAPIDLY BEHIND THE FRONT DURING THE PREDAWN HOURS FRIDAY. WINDS WILL RAPIDLY REACH GALE FORCE TO 45 KTS FRIDAY WITH A DIMINISHING TREND BEGINNING AFTER DARK FRIDAY EVENING. SURFACE HIGH PRESSURE WILL BUILD INTO THE AREA SATURDAY BRINGING A PERIOD OF LIGHT WINDS LASTING ONLY UNTIL DAYBREAK SUNDAY WHEN SOUTHERLY FLOW WILL AGAIN INCREASE AHEAD OF AN APPROACHING FRONTAL BOUNDARY. ED F && .LOT WATCHES/WARNINGS/ADVISORIES... IL...FLOOD WATCH...ILZ003-ILZ004-ILZ005-ILZ006-ILZ008-ILZ010-ILZ011- ILZ012-ILZ013-ILZ014-ILZ019-ILZ020-ILZ021-ILZ022-ILZ023- ILZ032-ILZ033-ILZ039 UNTIL 7 AM FRIDAY. IN...FLOOD WATCH...INZ001-INZ002-INZ010-INZ011-INZ019 UNTIL 7 AM FRIDAY. LM...GALE WATCH...LMZ080-LMZ261-LMZ362-LMZ364-LMZ366-LMZ563-LMZ565- LMZ567-LMZ669-LMZ671-LMZ673-LMZ675-LMZ777-LMZ779-LMZ868- LMZ870-LMZ872-LMZ874-LMZ876-LMZ878...7 AM FRIDAY TO 4 AM SATURDAY. GALE WARNING...LMZ740-LMZ741-LMZ742...7 AM THURSDAY TO 7 PM THURSDAY. SMALL CRAFT ADVISORY...NEARSHORE WATERS UNTIL 7 AM THURSDAY. GALE WARNING...LMZ743-LMZ744-LMZ745...7 AM THURSDAY TO 10 PM THURSDAY. && $$
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
1059 PM CDT WED APR 17 2013 .DISCUSSION... 934 PM CDT EVENING/MESOSCALE UPDATE... HAVE CANCELLED REMAINING CONVECTIVE WATCHES...THOUGH FLOODING WILL CONTINUE TO BE A SIGNIFICANT ISSUE THROUGH THURSDAY AND BEYOND. WARM FRONT EXTENDS FROM LOW PRESSURE WAVE OVER WESTERN MISSOURI... NORTHEAST INTO CENTRAL ILLINOIS AND CENTRAL INDIANA AT 02Z. OUTFLOW FROM PERSISTENT ELEVATED THUNDERSTORMS ACROSS IA/NORTHERN IL/IN HAS CONTINUED TO SUPPRESS SURFACE WARM FRONT SOUTH OF THE CWA...AND WILL LIKELY CONTINUE TO DO SO OVERNIGHT BEFORE DEEPENING SURFACE LOW LIFTS FROM MISSOURI INTO NORTHWEST IL IN ASSOCIATION WITH SHORT WAVE LIFTING OUT OF BASE OF UPPER TROUGH OVER THE SOUTHERN PLAINS. UNFORTUNATELY...THIS WILL RESULT IN CONTINUED FORCED ASCENT ATOP CONVECTIVELY ENHANCED FRONTAL ZONE TONIGHT WITHIN A BROAD REGION OF PERSISTENT STRONG WARM/MOIST ADVECTION AHEAD OF DEEP UPPER TROUGH OVER THE PLAINS. ILX 00Z SOUNDING TELLS THE STORY WITH RESPECT TO THE DIMINISHED SEVERE THREAT WITH STRONG LOW LEVEL INVERSION NORTH OF FRONT PREVENTING NEAR SFC-BASED STORMS. RAP GUIDANCE CONTINUES TO DEPICT A GRADIENT IN THE MUCAPE FIELD INCREASING TO 500-1000 J/KG AS YOU MOVE FARTHER SOUTH OF I-80. WHILE EFFECTIVE BULK SHEAR IN EXCESS OF 60 KT WILL CONTINUE TO ALLOW SOME ORGANIZATION FOR ELEVATED CONVECTION NORTH OF WARM FRONT...THE THREAT OF SEVERE WEATHER SHOULD BE LIMITED TO MARGINAL HAIL WITH THE BETTER ORGANIZED STORMS. WHILE THE SEVERE THREAT INTO THE OVERNIGHT HOURS IS RATHER LOW... FLOODING THREAT CONTINUES TO BE SIGNIFICANT INTO THURSDAY. RADAR ESTIMATES AND OBSERVED RAINFALL REPORTS INDICATE THAT MOST AREAS HAVE SEEN UPWARDS OF 0.75 INCHES OF RAIN...WITH MANY AREAS BETWEEN 1.5 AND 2.0 INCHES AND PARTS OF NORTH CENTRAL ILLINOIS IN EXCESS OF 2.5 INCHES. ILX 00Z RAOB DEPICTS PWAT OF 1.38 INCHES...199 PERCENT OF NORMAL...AN INDICATION OF THE VERY MOIST AIR MASS. ADDITIONAL RAINFALL AMOUNTS IN THE 1-2 INCH RANGE ARE VERY LIKELY THROUGH THURSDAY...LIKELY LEADING TO EXTENSIVE FLOODING ON AREA STREAMS AND RIVERS. AERIAL FLOOD WARNINGS REMAIN IN EFFECT INTO MIDDAY THURSDAY...AND MANY RIVER FORECAST SITES ARE HEADED FOR MODERATE TO MAJOR FLOODING. RATZER //PREV DISCUSSION... 342 PM CDT .SHORT TERM...THROUGH FRIDAY... HAZARDOUS WEATHER ISSUES FROM SEVERE THUNDERSTORMS TO EXCESSIVE RAINFALL TO TORNADIC POTENTIAL WILL IMPACT THE REGION THROUGH THURSDAY NIGHT. FOR THE REMAINDER OF THE AFTERNOON AND INTO THIS EVENING...AT 230PM CDT...STRONG THUNDERSTORMS EXTEND ALONG A LINE FROM NEAR WAUKEGAN...SOUTHWEST THROUGH OTTAWA. WEST OF THIS LINE...AN EXTENSIVE AREA OF OVERRUNNING PCPN WITH EMBEDDED THUNDER EXTENDED BACK THROUGH ERN IOWA AND MISSOURI. MUCH OF THE ACTIVITY OVER NRN IL HAS FORMED ALONG AN ELEVATED WARM FRONT...BUT A MORE SOLID LINE HAS DEVELOPED IN THE WARM SECTOR. EXPECT THAT THE THUNDERSTORMS WILL SAG SEWD THROUGH THE EVENING...BRINGING SHOWERS AND THUNDERSTORMS INTO EAST-CENTRAL ILLINOIS AND NORTHWESTERN INDIANA. WITH COPIOUS AMOUNTS OF MOISTURE STREAMING INTO THE REGION...THE STORMS HAVE BEEN VERY EFFICIENT RAIN PRODUCERS...WITH 0.81 INCHES OF RAIN MEASURED AT THE ROCKFORD AIRPORT BTWN 12-18Z THIS MORNING. STORMS HAVE ALSO BEEN MARGINALLY SEVERE WITH NUMEROUS REPORTS OF SMALL HAIL RECEIVED...AND A FEW REPORTS OF LARGER HAIL AS WELL. THIS WILL BE THE CONVECTIVE MODE FOR THE REMAINDER OF THE EVENING AND OVERNIGHT TONIGHT...WITH MODERATE TO HEAVY RAIN AND SMALL HAIL AND OCCASIONAL STRONG WINDS GUSTS. THE FLOODING AND SEVERE WEATHER POTENTIAL WILL RAMP UP EVEN FURTHER TOMORROW AS THE UPPER TROUGH MOVES OUT OVER THE CENTRAL PLAINS AND A SFC LOW DEEPENS. THE SFC LOW WILL SWING THROUGH THE SOUTH HIGH PLAINS EARLY THIS EVENING BEFORE TURNING NEWD...RIPPLING ALONG A QUASI-STATIONARY COLD FRONT AND WARM FRONT. BY THURSDAY MORNING...THE LOW WILL ELONGATE FROM NWRN IL THROUGH NWRN MO...WITH THE SFC WARM FRONT EXTENDING NEWD ACROSS CENTRAL LAKE MICHIGAN. THIS WILL PUT THE CWA FIRMLY IN THE WARM SECTOR. WITH A WIDE OPEN GLFMEX...DEEP LAYER MOISTURE WILL STREAM NWD INTO THE REGION...WITH PWATS EXCEEDING 1.5 INCHES FOR AN EXTENDED PERIOD OF TIME...LEADING TO THE POTENTIAL FOR SIGNIFICANT WIDESPREAD RIVER AND AREAL FLOODING. SEE THE HYDROLOGY SECTION FOR FURTHER DETAILS. THE SEVERE WEATHER MODE SHOULD FOCUS ON STRONG...DAMAGING WINDS AND POSSIBLE TORNADOES. THE LATEST SPC DAY 2 CONVECTIVE OUTLOOK HAS INCREASED THE AREA SOUTH OF A LINE FROM EVANSTON TO PONTIAC TO A MODERATE RISK...WITH THE REMAINDER OF THE AREA IN A SLIGHT RISK. INCREASING HEAT AND MOISTURE...TEMPERATURES REACHING INTO THE LOW TO MIDDLE 70S AND DEW POINTS IN THE LOW TO MIDDLE 60S IN THE WARM SECTOR...INSTABILITY WILL BE AMPLE. WHILE THE GENERAL CONVECTIVE MODE WILL BE LINEAR WITH SMALL LINES AND BOWS POSSIBLE...PRODUCING DAMAGING WINDS...THE MODEL GUIDANCE IS IN GOOD AGREEMENT ON A STRONG LOW LEVEL JET...WITH SWLY WINDS OF 55-65KT ACROSS THE REGION. WHILE SFC WINDS ARE GENERALLY PROGGED TO BE SOUTHERLY...THERE WILL BE OPPORTUNITY FOR SFC WINDS TO BACK A LITTLE MORE EAST OF SOUTH AS THE SFC LOW TRACKS THROUGH NWRN IL AND INTO SRN WI. GIVEN THE AMPLE INSTABILITY...COMBINED WITH CLOCKWISE TURNING HODOGRAPHS...DISCRETE SUPER CELLS MAY DEVELOP OUT IN THE WARM SECTOR AHEAD OF THE LINEAR CONVECTION...WHICH WOULD BRING THE TORNADIC POTENTIAL TO THE REGION. THE POTENTIAL FOR SEVERE WEATHER AND HEAVY RAINFALL WILL CONTINUE UNTIL THE ASSOCIATED COLD FRONT PUSHES THROUGH THE REGION...BRINGING IN MUCH COOLER AIR. THE GUIDANCE IS IN GOOD AGREEMENT ON PUSHING THE FRONT ACROSS THE AREA THURSDAY EVENING. AS THE SFC LOW PUSHES OFF TO THE NORTHEAST...THE UPPER TROUGH WILL ALSO CROSS THE AREA. WITH PLENTY OF RESIDUAL SFC MOISTURE AND COOLER AIR AND CYCLONIC CURVATURE ALOFT...SOME LINGERING INSTABILITY SHOWERS SHOULD PERSIST INTO FRIDAY. HIGHS ON FRIDAY SHOULD DROP BACK INTO THE MIDDLE TO UPPER 40S. KREIN .LONG TERM - SATURDAY THROUGH WEDNESDAY... SPRAWLING SURFACE HIGH PRESSURE TO BUILD INTO THE AREA SATURDAY BEHIND DEPARTING SURFACE LOW/UPPER LEVEL TROUGH. A RETURN TO UNSEASONABLY COOL TEMPS WITH A NEEDED BREAK IN PRECIPITATION WILL BE SHORT LIVED HOWEVER AS THE UPPER FLOW QUICKLY RETURNS SOUTHWESTERLY AS ANOTHER POWERFUL SHORTWAVE TROUGH DIGS INTO WESTERN NORTH AMERICA ON SUNDAY. THIS SHORTWAVE CARVES OUT A TROUGH ACROSS THE MOUNTAIN WEST SUNDAY NIGHT INTO MONDAY. A SERIES OF UPPER LEVEL SHORT WAVE TROUGHS WILL THEN RIPPLE NORTHEAST IN THE SW FLOW ALOFT. SPECIFIC FEATURES ARE POORLY RESOLVED BY MEDIUM RANGE MODELS BUT OVERALL TREND WILL BE A RETURN TO INCREASING MOISTURE AS GULF OPENS BACK UP AGAIN. MEDIUM RANGE MODELS ARE IN FAIRLY GOOD AGREEMENT IN CONCEPT IN SAGGING THE SURFACE FRONTAL BOUNDARY SOUTH ACROSS THE LOCAL AREA MONDAY NIGHT AND STALLING IT OUT TUESDAY SETTING THE STAGE FOR ANOTHER PROLONGED PERIOD OF WET WEATHER TUESDAY INTO WEDNESDAY AS RIPPLES OF LOW PRESSURE LIFT NORTHEAST ALONG THE BOUNDARY. EF && .HYDROLOGY... 350 PM CDT WITH SFC DEW POINTS EXPECTED TO REACH INTO THE LOWER TO MIDDLE 60S AND PWATS POSSIBLY REACHING AS HIGH AS 1.75 INCHES...ANY THUNDERSTORMS THAT DEVELOP WILL BE EFFICIENT RAIN PRODUCERS. BASED ON THE MATT BUNKERS PWAT CLIMATOLOGY...THESE VALUES APPROACH RECORD LEVELS. SO...FLOODING WILL BE A MAJOR CONCERN FOR THE ENTIRE CWA...WITH STORM TOTAL PCPN AMOUNTS OF 2-3 INCHES OVER THE SERN PORTIONS OF THE CWA...GENERALLY SOUTH OF I-80...AND 3-4 INCHES TO THE NORTH. LATEST LOCAL QPF WOULD SUGGEST AN AREA OF PCPN OF 4-5 INCHES IS POSSIBLE ALONG OVER NORTHERN ILLINOIS. THIS REPRESENTS AN INCREASE OVER PREVIOUS FORECASTS...BUT GIVEN THE RECORD LEVEL PWATS FOR AN EXTENDED PERIOD OF TIME...CONFIDENCE IS INCREASING FOR THIS SIGNIFICANT RAINFALL. WITH MANY RIVERS AND STREAMS ARE ALREADY NEAR OR ABOVE MINOR FLOOD STAGE...THIS AMOUNT OF RAIN WILL BRING ADDITIONAL RISES TO MODERATE AND MAJOR FLOOD LEVEL. IN ADDITION TO RIVER FLOODING...AREAL FLOODING OR RURAL...SUBURBAN AND URBAN AREAS IS LIKELY...WITH LOW LYING ROADS AND VIADUCTS FLOODING...AS WELL AS...ROADSIDE DRAINAGE DITCHES AND DRAINAGE PONDS EXCEEDING CAPACITY. AREAS NOT SEEING FLOODING WILL AT LEAST SEE AREAS OF STANDING OR PONDING WATER ON ROADS. KREIN && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 03Z... * WIDESPREAD -RA TO RA DURING THE NIGHT WITH PERIODS OF TS AND +RA. * WIDESPREAD MVFR WITH AND AREAS IFR OVERNIGHT...IMPROVING DAYBREAK OR SOON THEREAFTER. * ENE SFC GRADUALLY BECOME SSE AND BECOMING MODERATELY GUSTY BY DAYBREAK...AND INCREASINGLY GUSTY FROM SSE-SSW WINDS DURING THE DAY. TRS //DISCUSSION...UPDATED 00Z... MULTIPLE SHORT WAVES CONTINUE/TO CONTINUE TO MOVE FROM THE SOUTHERN PLAINS NORTHEASTWARD ACROSS THE MID MO AND MID AND UPPER MS VALLEYS TO THE WESTERN GREAT LAKES TONIGHT AND THU AS THE UPPER UPPER TROUGH CONTINUE TO MOVE E FROM THE ROCKIES AND OVER THE PLAINS. THESE MULTIPLE SMALL TO MEDIUM DISTURBANCES ARE EXPECTED TO CONTINUE TO PERIODICALLY CAUSE INCREASED RA COVERAGE AND NUMBER OF TS OVER THE CHI TERMINALS ALONG AND N OF THE SURFACE BOUNDARY TONIGHT AS THEY LIFT NE TOWARD AN THEN OVER THE LOCAL AREA. PROFILER...VAD AND RAOB WIND MEASUREMENTS CONFIRM INCREASING S TO SW FLOW ABOVE THE INCREASINGLY SHALLOW BOUNDARY LAYER WITH SPEED OF 50 TO 60KT WITHIN 1 TO 2K FT OF SURFACE BY LATE OVERNIGHT TONIGHT AND HAVE CONTINUED LLWS FORECASTS DURING THE NIGHT IN 00Z SET OF TAFORS. MVFR AND AREAS OF IFR CEILINGS EXPECTED TO PERSIST N OF THE SURFACE FRONT TIL IT LIFTS NORTHWARD AND ACROSS THE LOCAL TERMINALS DURING THE PREDAWN TO EARLY MORNING HOURS OF THU. WITH THE WARM FRONT TO THE N OF THE LOCAL AREA BY EARLY THU MORNING THE STRONGEST FORCING RESULTING FROM THE VERY STRONG LOW LEVEL WAA AND CONVERGENCE IS ANTICIPATED TO SHIFT GENERALLY TO THE N OF THE LOCAL TERMINALS THOUGH ACROSS THE LOCAL AREA S OF THE BOUNDARY SURFACE BASED INSTABILITY WILL BE INCREASING DURING THU SO CANNOT RULE OUT SCATTERED TSRA FROM MID AFTERNOON INTO EARLY EVENING. TRS //ORD AND MDW CONFIDENCE...UPDATED 03Z... * HIGH CONFIDENCE IN FORECAST WIND TRENDS. * MODERATE CONFIDENCE IN TIMING OF TIME FRAMES FOR MORE WIDESPREAD RA AND +TSRA. * LOW CONFIDENCE IN ONSET OF WIDESPREAD IFR AND IMPROVEMENT BACK THROUGH MVFR TO IFR THU MORNING. TRS //OUTLOOK FOR ORD/MDW FOR 12Z FRIDAY-12Z WEDNESDAY...UPDATED 00Z... FRIDAY...VFR...CHANCE SHRA WITH LOCAL MVFR. SATURDAY...VFR...LAKE BREEZE DEVELOPING AND REACHING CHI TERMINALS EARLY-MID AFTERNOON. SUNDAY...VFR...SLIGHT CHANCE SHRA. MONDAY...VFR...CHANCE SHOWERS. TUESDAY...MVFR LOWERING TO IFR....CHANCE OF SHOWERS. TRS && .MARINE... 420 PM CDT A PAIR OF LOW PRESSURE CENTERS OVER NORTHERN MISSOURI AND THE TEXAS PANHANDLE WILL MOVE NORTHEAST TONIGHT AND THURSDAY AND OVERSPREAD THE GREAT LAKES AREA. A BRIEF PERIOD OF OCCASIONALLY GALE FORCE GUSTS WILL OCCUR ACROSS SOUTHERN LAKE MICHIGAN THURSDAY AS THE SURFACE PRESSURE GRADIENT INTENSIFIES SOUTH OF THE ELONGATED LOW PRESSURE AREA FROM THE SAULT TO GREEN BAY. AS LOW PRESSURE LOCATES NEAR MILWAUKEE THURSDAY EVENING AND THEN MOVES NORTHEAST TO THE STRAITS OF MACKINAC BY DAYBREAK FRIDAY... A POWERFUL COLD FRONT WILL SURGE EAST ACROSS THE LAKE WITH WINDS INCREASING RAPIDLY BEHIND THE FRONT DURING THE PREDAWN HOURS FRIDAY. WINDS WILL RAPIDLY REACH GALE FORCE TO 45 KTS FRIDAY WITH A DIMINISHING TREND BEGINNING AFTER DARK FRIDAY EVENING. SURFACE HIGH PRESSURE WILL BUILD INTO THE AREA SATURDAY BRINGING A PERIOD OF LIGHT WINDS LASTING ONLY UNTIL DAYBREAK SUNDAY WHEN SOUTHERLY FLOW WILL AGAIN INCREASE AHEAD OF AN APPROACHING FRONTAL BOUNDARY. ED F && .LOT WATCHES/WARNINGS/ADVISORIES... IL...FLOOD WATCH...ILZ003-ILZ004-ILZ005-ILZ006-ILZ008-ILZ010-ILZ011- ILZ012-ILZ013-ILZ014-ILZ019-ILZ020-ILZ021-ILZ022-ILZ023- ILZ032-ILZ033-ILZ039 UNTIL 7 AM FRIDAY. IN...FLOOD WATCH...INZ001-INZ002-INZ010-INZ011-INZ019 UNTIL 7 AM FRIDAY. LM...GALE WATCH...LMZ080-LMZ261-LMZ362-LMZ364-LMZ366-LMZ563-LMZ565- LMZ567-LMZ669-LMZ671-LMZ673-LMZ675-LMZ777-LMZ779-LMZ868- LMZ870-LMZ872-LMZ874-LMZ876-LMZ878...7 AM FRIDAY TO 4 AM SATURDAY. GALE WARNING...LMZ740-LMZ741-LMZ742...7 AM THURSDAY TO 7 PM THURSDAY. SMALL CRAFT ADVISORY...NEARSHORE WATERS UNTIL 7 AM THURSDAY. GALE WARNING...LMZ743-LMZ744-LMZ745...7 AM THURSDAY TO 10 PM THURSDAY. && $$
AREA FORECAST DISCUSSION
NWS DODGE CITY KS
1234 AM CDT THU APR 18 2013 ...UPDATED AVIATION SECTION... .SYNOPSIS... ISSUED AT 1140 PM CDT WED APR 17 2013 A STRONG MID TO UPPER LEVEL TROUGH OF LOW PRESSURE IS CURRENTLY POSITIONED ACROSS THE CENTRAL AND NORTHERN ROCKIES WITH A MID TO UPPER LEVEL RIDGE OF HIGH PRESSURE ACROSS THE SOUTHEAST UNITED STATES. THIS PLACES WESTERN KANSAS UNDER SOUTHWEST FLOW ALOFT. TOWARDS THE SURFACE, AN AREA OF LOW PRESSURE IS CURRENTLY LOCATED ACROSS THE KS/MO BORDER WITH AN ASSOCIATED COLD FRONT STRETCHING SOUTHWEST ACROSS OKLAHOMA. NORTHERLY WINDS ARE OBSERVED ACROSS THE FORECAST AREA WITH MOSTLY CLOUDY SKIES. SHOWERS AND THUNDERSTORMS CONTINUE ACROSS CENTRAL AND SOUTH CENTRAL KANSAS WITH LIGHTER PRECIPITATION FALLING WEST OF THIS AREA. TEMPERATURES HAVE FALLEN BELOW FREEZING ACROSS PORTIONS OF WEST CENTRAL AND SOUTHWEST KANSAS ALLOWING A WINTRY MIX TO BE OBSERVED. RAIN, DRIZZLE, FREEZING DRIZZLE, SLEET, SNOW, AND SMALL HAIL HAVE BEEN REPORTED IN AREAS WEST OF HAYS TO MEADE LATE THIS EVENING. NO REPORTS OF ACCUMULATION HAVE BEEN REPORTED AT THIS TIME. && .SHORT TERM...(THIS EVENING THROUGH THURSDAY) ISSUED AT 343 PM CDT WED APR 17 2013 THERE WILL BE A CONTINUED THREAT FOR SEVERE WEATHER OVER SOUTH CENTRAL KANSAS THIS EVENING. THE NAM IS INDICATING THAT THE 850 MB FRONTAL BOUNDARY WILL BE IN THE AREA FROM COLDWATER AND MEDICINE LODGE TO ST JOHN THIS EVENING BEFORE SHIFTING SOUTH OF THE AREA BY MIDNIGHT. RAP MODEL SOUNDINGS SHOW AROUND 1500 J/KG OF ELEVATED CAPE IN THAT AREA. AS THE SOUTHWESTERN U.S. UPPER JET PROPAGATES EASTWARD INTO THE SOUTHERN PLAINS THIS EVENING...INCREASING UPWARD VERTICAL MOTION COULD AID IN THE DEVELOPMENT OF ADDITIONAL THUNDERSTORMS. THERE WILL BE A THREAT FOR HAIL UP TO QUARTER SIZE IN THAT AREA. THE UPPER TROUGH MOVES EAST OUT OVER THE HIGH PLAINS TONIGHT. MODEL SOUNDINGS ARE INDICATING SATURATED CONDITIONS GENERALLY BELOW 700 MB THROUGH THE NIGHT WITH THE LEVELS ABOVE 700 MB SATURATING FOR A 3-6 HOUR TIME FRAME DURING THE NIGHT. LOCATIONS FARTHER WEST ACROSS WESTERN KANSAS WILL SEE AREAS OF DRIZZLE CONTINUING ALONG WITH A CHANCE FOR RAIN SHOWERS. THERE WILL BE A TRANSITION FROM RAIN TO SNOW WITH A PERIOD OF SLEET/FREEZING RAIN POSSIBLE IN BETWEEN. THE ATMOSPHERE SHOULD COOL OFF ENOUGH FOR SNOW TO DEVELOP OVER WEST CENTRAL KANSAS DURING THE EVENING HOURS WITH THIS SPREADING INTO CENTRAL KANSAS AFTER MIDNIGHT. GIVEN THE SHORT WINDOW OF OPPORTUNITY FOR THE SEEDER/FEEDER MECHANISM TO OCCUR...DO NOT EXPECT SNOW AMOUNTS TO BE SIGNIFICANT WITH ONLY SOME LIGHT ACCUMULATIONS POSSIBLE ON GRASSY AREAS. AM NOT ANTICIPATING ANY SIGNIFICANT ICE ACCUMULATIONS TO OCCUR ALTHOUGH SOME ELEVATED SURFACES COULD GET SOME LIGHT COATINGS. AS COLD AIR ADVECTION INCREASES...STRONG NORTHERLY WINDS DEVELOP OVER THE WESTERN HIGH PLAINS AND SPREAD EASTWARD TONIGHT. LOW LEVEL WINDS THROUGH THE 850 MB LEVEL INCREASE TO 40-50 KNOTS OVERNIGHT WHICH SHOULD SUPPORT WIND ADVISORY CRITERIA WINDS LATER TONIGHT INTO THURSDAY MORNING. HAVE ISSUED A WIND ADVISORY FOR MIDNIGHT TONIGHT UNTIL NOON THURSDAY FOR ALL OF SOUTHWEST AND CENTRAL KANSAS. PRECIPITATION SHOULD BE WINDING DOWN FAIRLY QUICKLY LATE TONIGHT AND THURSDAY MORNING AS THE UPPER SYSTEM MOVES EAST OF THE REGION. CLOUDS SHOULD BE BREAKING UP FROM WEST TO EAST DURING THE DAY. WITH SOME SUN...AFTERNOON HIGH TEMPERATURES MAY BE ABLE TO CLIMB INTO THE LOWER 40S. .LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY) ISSUED AT 338 PM CDT WED APR 17 2013 FRIDAY: UPPER LEVEL WNW FLOW WILL CONTINUE ON FRIDAY. AT THE SURFACE, HIGH PRESSURE WILL RIDGE ACROSS THE PLAINS. NORTHWESTERLY WINDS WILL EVENTUALLY BECOME SOUTHERLY AFTER SUNSET. HIGHS WILL BE IN THE 50S AND LOWS WILL BE IN THE 20S. NO PRECIPITATION IS EXPECTED AS DRY FLOW ALOFT AND LACK OF BL MOISTURE CONTINUES. WEEKEND: AN UPPER LEVEL TROUGH WILL DIG ACROSS THE CENTRAL AND SOUTHERN ROCKIES THROUGH THE WEEKEND. THIS WILL PROMOTE A WARM AIR ADVECTION PATTERN DOWNSTREAM ACROSS OUR REGION. A WARM 850 HPA PLUME WILL ADVECT OFF THE ROCKIES AND OUT ACROSS SOUTHWEST KANSAS SATURDAY. THIS WILL FAVOR DEEP MIXING AND HIGHS IN THE UPPER 60S TO LOWER 70S. OVERNIGHT LOWS WILL MODERATE AS WELL WITH 30S ON SATURDAY AND 40S ON SUNDAY. TEMPERATURES AROUND 70 DEG F CAN BE EXPECTED SUNDAY AS THE AFOREMENTIONED WARM PLUME CONTINUES ACROSS THE REGION. THERE COULD BE A FEW SHOWERS ACROSS SC/S KANSAS IN ASSOCIATION WITH WARM ADVECTION BUT CONFIDENCE IS LOW AND MODELS ARE FAIRLY LIGHT ON QPF. NEXT WEEK AND BEYOND: A MAJOR CHANGE IN WEATHER IS POSSIBLE MONDAY OR TUESDAY. ANOTHER TROF DIGGING OUT OF THE NORTHERN ROCKIES WILL USHER IN THE PASSAGE OF A SIGNIFICANT COLD FRONT. THE ECMWF IS FAIRLY COLD WITH 850 HPA TEMPERATURES DECREASING DOWN TO -6 DEG C. BOTH THE GFS AND ECMWF INDICATE SOME LIGHT SNOWFALL ACROSS THE REGION ASSOCIATED WITH THIS FRONT. CONFIDENCE IS LOW FOR PRECIPITATION TYPE BUT THERE IS HIGHER CONFIDENCE IN LOWER TEMPERATURES WITH 40S AND 50S FOR HIGHS BY TUESDAY/WEDNESDAY. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT) ISSUED AT 1228 AM CDT THU APR 18 2013 MVFR TO IFR CONDITIONS WILL CONTINUE ACROSS THE TAF SITES EARLY THIS MORNING AS A STRONG STORM SYSTEM MOVES THROUGH THE CENTRAL PLAINS. TEMPERATURES HAVE FALLEN TO BELOW FREEZING AT THE SURFACE BUT A WARM TOUNGE ALOFT SHOULD KEEP MOST PRECIPITATION FROM TURNING TO SNOW. I HAVE PLACED FREEZING RAIN IN THE TAFS FOR NOW WITH THE ONLY MENTION OF SNOW IN THE GCK TAF AS PART OF A TEMPO GROUP. HOWEVER, TEMPERATURES MAY FALL MORE RAPIDLY THAN EXPECTED ALLOWING SNOW TO BE POSSIBLE CLOSER TO DAY BREAK. CLOUDY SKIES CONTINUE THROUGHOUT THE DAY WITH SOME CLEARING LATE THIS EVENING. STRONG NORTHERLY WINDS WILL BE FELT WITH THIS SYSTEM AND CONTINUE THROUGHOUT THE DAY. A DECREASE IN WINDS AND A SHIFT TO THE NORTHWEST IS EXPECTED TOMORROW EVENING INTO TOMORROW NIGHT. && .PRELIMINARY POINT TEMPS/POPS... DDC 24 59 34 69 / 0 0 0 10 GCK 22 60 33 68 / 0 0 0 10 EHA 23 60 33 70 / 0 0 0 10 LBL 23 60 33 71 / 0 0 0 10 HYS 23 58 33 64 / 0 0 0 10 P28 28 60 36 66 / 0 0 0 10 && .DDC WATCHES/WARNINGS/ADVISORIES... WIND ADVISORY UNTIL NOON CDT /11 AM MDT/ TODAY FOR KSZ030-031- 043>046-061>066-074>081-084>090. && $$ SYNOPSIS...HOVORKA_42 SHORT TERM...GERARD LONG TERM...SUGDEN AVIATION...HOVORKA_42
AREA FORECAST DISCUSSION
NWS WICHITA KS
1226 AM CDT THU APR 18 2013 .UPDATE... ISSUED AT 1226 AM CDT THU APR 18 2013 UPDATED TO AVIATION SECTION BELOW. && UPDATE ISSUED AT 711 PM CDT WED APR 17 2013 THUNDERSTORMS HAVE YET TO FORM ALONG THE SURFACE FRONT OVER SOUTHEAST KS. INSPECTION OF MODIFIED RUC SOUNDINGS INDICATE POOR LAPSE RATES/RELATIVELY WARM TEMPERATURES THROUGH 700-600MB. SO DESPITE GOOD CONVERGENCE ALONG THE SURFACE FRONT...NEAR-SURFACE COLD AIR IS LIKELY TOO SHALLOW TO BREAK THROUGH THE WARMER MID-LEVEL TEMPERATURES...WITH ONLY WEAK BUOYANCY FROM THE SURFACE-700/600MB. CONSEQUENTLY...FEEL THE HIGH- END SEVERE WEATHER THREAT INCLUDING TORNADOES...DAMAGING WINDS AND VERY LARGE HAIL IS WANING...ALTHOUGH STILL CANNOT RULE OUT SEVERE ACTIVITY EITHER DEVELOPMENT OVER MOVING NORTHEAST OUT OF OK INTO SE KS. WONDERING IF THE HIGHER CONFIDENCE SCENARIO (SUPPORTED BY THE RUC)...IS SHOWERS/THUNDERSTORMS RAMPING UP IN COVERAGE/INTENSITY LATER THIS EVENING OVER SOUTH-CENTRAL/CENTRAL KS IN RESPONSE TO INCREASING ISENTROPIC ASCENT AND MOISTURE TRANSPORT AHEAD OF APPROACHING DEEP MID/UPPER TROUGH...WITH A BROAD SHIELD OF MODERATE TO HEAVY SHOWERS/THUNDERSTORMS PUSHING EAST ACROSS EASTERN HALF OF KS OVERNIGHT ALONG THE ADVANCING 850-700MB FRONT. GIVEN THE PRESENCE OF AMPLE ELEVATED INSTABILITY AND EFFECTIVE DEEP LAYER SHEAR...LARGE HAIL IS POSSIBLE. POCKETS OF HEAVY RAIN AND MINOR FLOODING ARE POSSIBLE...ALONG WITH MODEST RISES IN AREA RIVERS...SO WILL KEEP THE FLOOD WATCH GOING OVER SOUTHEAST KS. ADDITIONALLY...ENOUGH LOW-LEVEL COLD AIR MAY FILTER SOUTHEAST TO RESULT IN A WINTRY MIX OVER CENTRAL KS AFTER MIDNIGHT...SO WILL KEEP A WINTER WX ADVISORY GOING THERE. ADK && .SHORT TERM...(THIS EVENING THROUGH SATURDAY) ISSUED AT 237 PM CDT WED APR 17 2013 CONVECTION PRE AND POST FRONTAL STRONG TO SEVERE CONVECTION WITH HEAVY RAINFALL EXPECTED THRU THIS EVENING ACROSS PORTIONS OF CENTRAL AND SOUTHEAST KANSAS. THE HIGHER IMPACT SEVERE IS STILL EXPECTED ALONG THE SURFACE FRONT ACROSS SOUTHEAST KANSAS WITH DAMAGING WINDS...LARGE HAIL AND A TORNADO POSSIBLE DURING THE EARLY EVENING. HOWEVER ELEVATED INSTABILITY OVER THE COLD AIR WILL STILL SUPPORT SOME HAILERS FURTHER WEST ACROSS PORTIONS OF CENTRAL KANSAS. CONVECTION WILL TEND TO REDEVELOP AND REPEAT/TRAIN OVER SOME AREAS WHICH PORTENDS TO HEAVY RAINFALL AND FLOOD POTENTIAL. THE LONGER DURATION APPEARS TO BE OVER SOUTHEAST KANSAS INTO THE OVERNIGHT HOURS...SO WILL ISSUE A FLOOD WATCH FOR THESE AREAS. WINTRY PRECIP NEXT CHALLENGE IS WITH THE SURGE OF COLD AIR AND POST FRONTAL PRECIPITATION LATER TONIGHT INTO THURSDAY MORNING. WHILE NOT QUITE AS IMPRESSIVE AS LAST WEEK...IT DOES LOOK LIKE WE WILL GET A TRANSIENT AREA OF A LIGHT WINTRY MIX ACROSS CENTRAL KANSAS WITH THE NAM PREFERRED IN THIS REGARD. DEPENDING ON CHANGEOVER AND MOISTURE DEPTH/LIFT...THIS COULD BE SOME LIGHT FREEZING RAIN AND/OR SNOW OR FREEZING DRIZZLE...THOUGH FOR NOW ANY ACCUMS ARE STILL EXPECTED TO BE LIGHT. THAT SAID...THIS IN COMBO WITH STRONG NORTH WINDS NEAR ADVISORY CRITERIA INTO EARLY THURSDAY MORNING...PLAN TO ISSUE A WINTER WEATHER ADVISORY FOR A PORTION OF CENTRAL KANSAS. SOME LIGHT MIXED PRECIP COULD BE OBSERVED AS FAR EAST AS THE FLINT HILLS INTO LATER THURSDAY MORNING...HOWEVER TEMPERATURES SHOULD RECOVER TO A BIT ABOVE FREEZING BY THEN SO OF LITTLE CONSEQUENCE EXPECTED. FREEZE/RECORD COLD THURSDAY NIGHT THE THIRD CONCERN IS WITH RECORD COLD AND WIDESPREAD FREEZE EXPECTED. THIS LOOKS TO BE A PURE COLD ADVECTION TYPE WITH MINS INTO THE MID TO UPPER 20S IN MOST LOCALES DESPITE A BIT OF NOCTURNAL/EARLY MORNING WIND. CONSIDERED A HEADLINE/WATCH FOR THIS...HOWEVER WITH THE OTHER MORE IMMINENT IMPACTS IN THE SHORTER TERM HAVE DECIDED TO HOLD OFF AND MAINTAIN MENTION IN THE HAZARDOUS WEATHER OUTLOOK. HOWEVER IF CONFIDENCE REMAINS HIGH...A FREEZE WARNING WILL LIKELY BE FORTHCOMING IN THE NEXT FORECAST CYCLE OR TWO. SOME MODERATION AND RETURN TO DRY WEATHER IS EXPECTED FOR FRIDAY AND SATURDAY AND MADE ONLY A SLIGHT UPTWEAK TO THE TEMPERATURES CLOSER TO SEASONAL CLIMO BY SATURDAY. DARMOFAL .LONG TERM...(SUNDAY THROUGH WEDNESDAY) ISSUED AT 237 PM CDT WED APR 17 2013 SINCE MAIN FOCUS HAS BEEN ON SHORT TERM DO NOT PLAN ON ANY SIGNIFICANT CHANGES TO THE OUTER PERIODS WITH THIS FORECAST. MEDIUM RANGE STILL SUPPORTS ANOTHER COOL DOWN EARLY NEXT WEEK WITH SOME PRECIP CHANCES AHEAD OF AND JUST BEHIND THE FRONTAL PASSAGE FROM SUNDAY INTO TUESDAY. DARMOFAL && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT) ISSUED AT 1226 AM CDT THU APR 18 2013 AREAS OF SHOWERS/THUNDERSTORMS WILL GRADUALLY EXIT THE REGION TO THE EAST AS THE OVERNIGHT PROGRESSES...AS A STRONG UPPER LEVEL TROUGH APPROACHES FROM THE WEST. THINKING ACTIVITY THE REMAINDER OF THE NIGHT WILL BE MOST WIDESPREAD AT KCNU. FURTHER NORTHWEST AT KRSL...WILL LIKELY SEE A PERIODIC WINTRY MIX OF LIGHT SLEET...SNOW AND PERHAPS PATCHY FREEZING DRIZZLE. SLEET/SNOW ACCUMULATIONS WILL LIKELY ONLY BE A FEW TENTHS OF AN INCH AT BEST...AND ICE ACCUMULATIONS ON ELEVATED SURFACES SHOULD BE LITTLE IF ANY. OTHERWISE...IFR TO LOW MVFR CIGS WILL GRADUALLY GIVE WAY TO VFR CIGS BY MID TO LATE MORNING THURSDAY ALL AREAS. ADDITIONALLY...STRONG AND GUSTY NORTHWEST WINDS WILL PREVAIL THROUGH THURSDAY. ADK && .FIRE WEATHER... ISSUED AT 237 PM CDT WED APR 17 2013 GRASSLAND FIRE DANGER WILL REMAIN LOW DUE TO WIDESPREAD PRECIPITATION TONIGHT INTO EARLY THURSDAY. A DRYING PROCESS WILL BEGIN INTO THE START OF THE WEEKEND BEFORE ANOTHER CHANCE FOR RAIN SUNDAY INTO EARLY NEXT WEEK. KED && .PRELIMINARY POINT TEMPS/POPS... WICHITA-KICT 28 56 36 66 / 0 0 0 10 HUTCHINSON 27 56 35 64 / 0 0 0 10 NEWTON 27 54 35 64 / 0 0 0 10 ELDORADO 28 55 35 65 / 0 0 0 10 WINFIELD-KWLD 29 59 37 67 / 0 0 0 10 RUSSELL 24 56 34 64 / 0 0 0 10 GREAT BEND 25 56 34 64 / 0 0 0 10 SALINA 26 55 35 65 / 0 0 0 10 MCPHERSON 26 56 35 64 / 0 0 0 10 COFFEYVILLE 31 58 36 66 / 10 0 0 10 CHANUTE 30 57 33 65 / 10 0 0 10 IOLA 30 56 33 65 / 10 0 0 10 PARSONS-KPPF 30 56 34 65 / 10 0 0 10 && .ICT WATCHES/WARNINGS/ADVISORIES... WINTER WEATHER ADVISORY UNTIL 7 AM CDT THIS MORNING FOR KSZ032- 033-047-048-050-067-082. FLOOD WATCH UNTIL 7 AM CDT THIS MORNING FOR KSZ070>072-094>096- 098>100. && $$
AREA FORECAST DISCUSSION
NWS GOODLAND KS
1055 PM MDT WED APR 17 2013 .SHORT TERM...(THIS AFTERNOON THROUGH THURSDAY) ISSUED AT 132 PM MDT WED APR 17 2013 EARLY AFTERNOON WV IMAGERY AND RAP H5 ANALYSIS SHOWS POSITIVELY TITLED LONGWAVE TROUGH EXTENDING SOUTH ALONG CENTRAL ROCKIES WITH DRY SLOT/AREA OF SUBSIDENCE IN PLACE AHEAD OF THIS OVER WESTERN KANSAS AND CENTRAL NEBRASKA. LOW AT THE SURFACE A STALLED FRONT EXTENDS FROM THE TEXAS PANHANDLE ACROSS CENTRAL OKLAHOMA TO SOUTHEAST KANSAS. NORTHWEST FLOW IS IN PLACE ACROSS OUR CWA WITH VERY MOIST BL CONDITIONS PERSISTING...WHICH HAS RESULTED IN AREAS OF FOG AND DRIZZLE PERSISTING THROUGH THE AFTERNOON HOURS. WITH TEMPERATURES NEAR OR BELOW FREEZING...WE COULD CONTINUE TO SEE LIGHT ICE ACCUMULATIONS ON ELEVATED SURFACES BEFORE SNOW DEVELOPS LATER. THE PRIMARY FORECAST FOCUS IS ON DEVELOPING WINTER STORM FOR LATE THIS AFTERNOON THROUGH EARLY THURSDAY MORNING. UPPER LEVEL TROUGH IS PROGGED TO SHIFT EAST THIS EVENING...WITH LARGE SCALE ASCENT AND MID LEVEL MOISTURE OVERSPREADING THE CWA. BROAD AXIS OF MID LEVEL FRONTOGENESIS IS EXPECTED TO SET UP ACROSS THE NORTHWEST HALF OF OUR CWA THIS EVENING. LIGHT SNOW AND BANDS OF MODERATE SNOW TRAINING FROM THE SOUTH TO THE NORTH. WITH SURFACE TEMPS ALREADY BELOW FREEZING THIS AFTERNOON IN THE NORTHWEST AND A SECOND COLD SURGE EXPECTED LATE THIS AFTERNOON/EARLY THIS EVENING...I THINK WE SHOULD SEE A FAST RAIN/SNOW CHANGEOVER WITH ALL SNOW IN OUR CWA THIS EVENING AND TONIGHT. THERE IS QUITE A BIT OF SPREAD REGARDING QPF VALUES...WITH GFS THE HIGH OUTLIER. WITH SREF (TRADITIONALLY HIGH) AND OTHER GUIDANCE MORE IN LINE WITH PREVIOUS FORECAST QPF/SNOW TOTALS I DISCOUNTED THE GFS SOLUTION AND ONLY MADE MINOR CHANGES TO AMOUNTS. WE ARE CURRENTLY FORECAST 3-5 INCHES FOR MOST OF THE AREA...WITH HIGHS AMOUNTS MORE LIKELY NORTH OF INTERSTATE 70. OTHER CONCERN (AND POSSIBLY THE HIGHER IMPACT) IS STRONG WINDS PROGGED TO DEVELOP THIS EVENING. ALL GUIDANCE IS SUPPORTIVE OF GUSTY WINDS...HOWEVER GFS/MAV CONTINUES TO BE THE HIGH OUTLIER WITH GUSTS IN EXCESS OF 60 MPH. NAM/SREF/ECMWF ALL ARE LOWER...AND WITH BEST PRESSURE RISES ADVERTISED TO BE FURTHER SOUTH...THESE SOLUTIONS MAY BE MORE REASONABLE. I USED A BLEND THAT FAVORED THE NAM MIXED LAYER WINDS AND NUDGED A LITTLE TOWARDS GFS/MAV WHICH RESULTS IN GUSTS THIS EVENING TO 50 MPH. EVEN WITH THE LOWER END OF GUIDANCE WE SHOULD SEE BLOWING SNOW WITH REDUCED VISIBILITIES. THE SPREAD IN GUIDANCE AND POSSIBLE LIMITED DURATION OF THE STRONGEST WINDS IN OUR AREA RAISES QUESTIONS TO HOW LOW THESE VISIBILITIES WILL BE AND HOW LONG. I FELT THE WINTER WEATHER ADVISORY WAS APPROPRIATE WITH BRIEF BLIZZARD CONDITIONS POSSIBLE. IF WINDS END UP BEING MORE IN LINE WITH GFS SOLUTION WE MAY NEED TO CONVERT WESTERN LOCATIONS TO A BLIZZARD WARNING...CONFIDENCE JUST ISNT THERE RIGHT NOW. THE WORST CONDITIONS SHOULD BE 03Z THROUGH ABOUT 09Z TONIGHT...WITH SNOW ENDING QUICKLY FROM THE WEST TO THE EAST EARLY THU MORNING. WE COULD SEE LINGERING SNOW INTO THU IN OUR NORTHEAST...HOWEVER WITH BEST FORCING/MOISTURE OUTSIDE OUR AREA I AM NOT ANTICIPATING VERY MUCH ADDITIONAL ACCUMULATION. WE SHOULD SEE ANOTHER BLUSTERY DAY THURSDAY WITH HIGHS IN THE 30S AND GUSTY WINDS THROUGH THE DAY. GFS/MAV IS AGAIN MUCH HIGHER ON WINDS THU AND MIGHT SUPPORT ADVISORY CRITERIA. I WILL HAVE TO SEE WHAT KIND OF BIAS THE GFS HAD TONIGHT TO HAVE ANY ANY CONFIDENCE IN THE HIGHER WINDS THURSDAY. .LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY) ISSUED AT 316 PM MDT WED APR 17 2013 FORECAST PROBLEMS WILL BE HOW MUCH IT WARMS UP THROUGH THE WEEKEND BEFORE THE NEXT COLD FRONT MOVES THROUGH AND THE PRECIPITATION CHANCES THIS WEEKEND AND CONTINUING INTO THE BEGINNING OF NEXT WEEK. SATELLITE SHOWING THE LARGE SCALE FLOW PATTERN BEING AMPLIFIED AND BLOCKY FROM THE PACIFIC INTO THE EASTERN NORTH AMERICA. THURSDAY NIGHT...SYSTEM THAT WILL HAVE BROUGHT THE AREA SNOW AND WIND WILL CONTINUE TO MOVE AWAY. MODERATE GRADIENT CONTINUES THROUGH THE NIGHT AND LOOKS LIKE THE WINDS WILL STAY UP ENOUGH TO KEEP THE TEMPERATURES FROM BOTTOMING OUT. FRIDAY/FRIDAY NIGHT...RIGHT REAR QUADRANT OF UPPER JET GOES ACROSS THE NORTHERN PORTION OF THE AREA DURING THE DAY. AT THIS TIME WITH A LARGE DRY LAYER IN THE LOW AND MID LEVELS...THIS ONLY LOOKS LIKE IT WILL SPREAD CLOUDS ACROSS THE AREA. DURING THE NIGHT...THE LEFT FRONT QUADRANT IS NEAR OR JUST SOUTHWEST OF THE SOUTHWEST PORTION OF OUR AREA. AS IT LOOKS THE MAIN MID LEVEL LIFT LOOKS TO STAY TO NORTH AND SOUTH OF THE AREA. ALSO PROBLEM AGAIN LOOKS TO BE A LACK OF MOISTURE IN THE LOW LEVELS. SO WILL KEEP THIS PERIOD DRY AS WELL. CLOUDS WILL DECREASE THROUGH THE NIGHT WITH THE MODELS SHOWING A HIGHLY VARIABLE WIND FIELD AND DISAGREE WITH EACH OTHER. WILL TEND TOWARD THE COOLER SIDE. SATURDAY...MAIN JET REMAINS SOUTH AND WEST OF THE AREA. HIGHER LEVEL CLOUD COVER INCREASES THROUGH THE DAY AS A COUPLE DIFFERENT SHORTWAVE TROUGHS MOVE THROUGH. THIS MAY HINDER THE TEMPERATURES. HOWEVER... MODELS HAVE BEEN MISSING THE BOAT ON TEMPERATURES HERE RECENTLY. HAVE A LIGHT AND VARIABLE WIND FIELD WHICH ALSO DOES NOT BODE WELL FOR GOING TOO WARM. MODELS HANDLE THIS DIFFERENTLY DUE TO THE DIFFERENT HANDLING OF THE INCOMING SYSTEM. 700 TO 500 MB PATTERN WOULD DEFINITELY SUPPORT AN EARLIER SURFACE TROUGH/FRONTAL PASSAGE. MORE SUPPORT FOR GOING WARMER SO DID NUDGE UP TEMPERATURES A LITTLE BUT NOT A LOT OF CONFIDENCE IN THIS DUE TO RECENT TEMPERATURE PERFORMANCE. NOT A LOT OF SURFACE CONVERGENCE WITH THIS WIND FIELD. PLUS ALL THE MOISTURE LOOKS TO BE ABOVE 700 MB. SO WILL KEEP THIS PERIOD DRY. SATURDAY NIGHT THROUGH WEDNESDAY...IN GENERAL THE MODELS ARE CAPTURING THE OVERALL PATTERN. THE MODELS DROP A SYSTEM INTO THE NORTH CENTRAL PORTION OF THE COUNTRY SUNDAY INTO MONDAY AND THEN BRING THE UPPER TROUGH THROUGH AROUND TUESDAY AND THEN EAST OF THE AREA. HOWEVER...THEY ARE DIFFERING ON THE TIMING OF THE NUMEROUS SHORTWAVE TROUGHS THAT MOVE THROUGH IN THE WESTERLY FLOW ALOFT PRIOR TO THE UPPER TROUGH MOVING THROUGH. THEY ALSO DIFFER IN HOW FAR SOUTH AND HOW FAST THEY TAKE THE UPPER TROUGH THROUGH. SO IN GENERAL THEY AGREE ON MAKING IT WET BUT NOT THE TIMING. THE BIGGEST PROBLEM ON TIMING CENTERS AROUND TUESDAY. THE ECMWF TAKES THE UPPER TROUGH THROUGH SOONER THAN THE GFS AND CANADIAN. SO DID NOT HAVE ANY PROBLEM WITH WHAT THE CRH INIT GAVE ME WHICH IS RAMPING UP POPS SUNDAY NIGHT WITH THE HIGHEST POPS MONDAY INTO MONDAY NIGHT. FOR TUESDAY THE INIT GAVE ME POPS IN THE MIDDLE OF THE TWO CAMPS AND COULD LIVE WITH THAT. AFTER TUESDAY IT LOOKS DRY. STRONG COLD FRONT COMES THROUGH LATE SUNDAY NIGHT INTO EARLY MONDAY MORNING. PER THIS RATHER FAST FRONTAL PASSAGE AND COLLABORATION CHOSE TO LOWER MONDAY AND TUESDAY MAXES FROM WHAT THE CRH INIT GAVE ME. OTHERWISE MADE NO OTHER CHANGES THANKS TO ALL FOR THE COLLABORATION && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT) ISSUED AT 1054 PM MDT WED APR 17 2013 LIGHT SNOW AND IFR/MVFR CONDITIONS WILL CONTINUE AT KGLD AND KMCK OVERNIGHT. CIGS AND VIS WILL IMPROVE THURSDAY MORNING BUT WIND WILL REMAIN BREEZY TO WINDY. VFR CONDITONS SHOULD RETURN TO BOTH TERMINALS IN THE AFTERNOON/EVENING AS THE UPPER TROUGH MOVES NORTHEAST OF THE AREA. && .CLIMATE... ISSUED AT 330 AM MDT WED APR 17 2013 RECORD LOW HIGH TEMPERATURES IN JEOPARDY THURSDAY: GOODLAND.....38 DEGREES HILL CITY....47 DEGREES MCCOOK.......35 DEGREES BURLINGTON...35 DEGREES YUMA.........36 DEGREES COLBY........39 DEGREES TRIBUNE......40 DEGREES && .GLD WATCHES/WARNINGS/ADVISORIES... KS...WINTER WEATHER ADVISORY UNTIL 6 AM MDT /7 AM CDT/ THURSDAY FOR KSZ001>004-013>016-027>029-041-042. CO...WINTER WEATHER ADVISORY UNTIL 6 AM MDT THURSDAY FOR COZ090>092. NE...WINTER WEATHER ADVISORY UNTIL 6 AM MDT /7 AM CDT/ THURSDAY FOR NEZ079>081. && $$ SHORT TERM...DR LONG TERM...BULLER AVIATION...FS CLIMATE...JTL
AREA FORECAST DISCUSSION
NWS DODGE CITY KS
1142 PM CDT WED APR 17 2013 ...UPDATED SYNOPSIS SECTION... .SYNOPSIS... ISSUED AT 1140 PM CDT WED APR 17 2013 A STRONG MID TO UPPER LEVEL TROUGH OF LOW PRESSURE IS CURRENTLY POSITIONED ACROSS THE CENTRAL AND NORTHERN ROCKIES WITH A MID TO UPPER LEVEL RIDGE OF HIGH PRESSURE ACROSS THE SOUTHEAST UNITED STATES. THIS PLACES WESTERN KANSAS UNDER SOUTHWEST FLOW ALOFT. TOWARDS THE SURFACE, AN AREA OF LOW PRESSURE IS CURRENTLY LOCATED ACROSS THE KS/MO BORDER WITH AN ASSOCIATED COLD FRONT STRETCHING SOUTHWEST ACROSS OKLAHOMA. NORTHERLY WINDS ARE OBSERVED ACROSS THE FORECAST AREA WITH MOSTLY CLOUDY SKIES. SHOWERS AND THUNDERSTORMS CONTINUE ACROSS CENTRAL AND SOUTH CENTRAL KANSAS WITH LIGHTER PRECIPITATION FALLING WEST OF THIS AREA. TEMPERATURES HAVE FALLEN BELOW FREEZING ACROSS PORTIONS OF WEST CENTRAL AND SOUTHWEST KANSAS ALLOWING A WINTRY MIX TO BE OBSERVED. RAIN, DRIZZLE, FREEZING DRIZZLE, SLEET, SNOW, AND SMALL HAIL HAVE BEEN REPORTED IN AREAS WEST OF HAYS TO MEADE LATE THIS EVENING. NO REPORTS OF ACCUMULATION HAVE BEEN REPORTED AT THIS TIME. && .SHORT TERM...(THIS EVENING THROUGH THURSDAY) ISSUED AT 343 PM CDT WED APR 17 2013 THERE WILL BE A CONTINUED THREAT FOR SEVERE WEATHER OVER SOUTH CENTRAL KANSAS THIS EVENING. THE NAM IS INDICATING THAT THE 850 MB FRONTAL BOUNDARY WILL BE IN THE AREA FROM COLDWATER AND MEDICINE LODGE TO ST JOHN THIS EVENING BEFORE SHIFTING SOUTH OF THE AREA BY MIDNIGHT. RAP MODEL SOUNDINGS SHOW AROUND 1500 J/KG OF ELEVATED CAPE IN THAT AREA. AS THE SOUTHWESTERN U.S. UPPER JET PROPAGATES EASTWARD INTO THE SOUTHERN PLAINS THIS EVENING...INCREASING UPWARD VERTICAL MOTION COULD AID IN THE DEVELOPMENT OF ADDITIONAL THUNDERSTORMS. THERE WILL BE A THREAT FOR HAIL UP TO QUARTER SIZE IN THAT AREA. THE UPPER TROUGH MOVES EAST OUT OVER THE HIGH PLAINS TONIGHT. MODEL SOUNDINGS ARE INDICATING SATURATED CONDITIONS GENERALLY BELOW 700 MB THROUGH THE NIGHT WITH THE LEVELS ABOVE 700 MB SATURATING FOR A 3-6 HOUR TIME FRAME DURING THE NIGHT. LOCATIONS FARTHER WEST ACROSS WESTERN KANSAS WILL SEE AREAS OF DRIZZLE CONTINUING ALONG WITH A CHANCE FOR RAIN SHOWERS. THERE WILL BE A TRANSITION FROM RAIN TO SNOW WITH A PERIOD OF SLEET/FREEZING RAIN POSSIBLE IN BETWEEN. THE ATMOSPHERE SHOULD COOL OFF ENOUGH FOR SNOW TO DEVELOP OVER WEST CENTRAL KANSAS DURING THE EVENING HOURS WITH THIS SPREADING INTO CENTRAL KANSAS AFTER MIDNIGHT. GIVEN THE SHORT WINDOW OF OPPORTUNITY FOR THE SEEDER/FEEDER MECHANISM TO OCCUR...DO NOT EXPECT SNOW AMOUNTS TO BE SIGNIFICANT WITH ONLY SOME LIGHT ACCUMULATIONS POSSIBLE ON GRASSY AREAS. AM NOT ANTICIPATING ANY SIGNIFICANT ICE ACCUMULATIONS TO OCCUR ALTHOUGH SOME ELEVATED SURFACES COULD GET SOME LIGHT COATINGS. AS COLD AIR ADVECTION INCREASES...STRONG NORTHERLY WINDS DEVELOP OVER THE WESTERN HIGH PLAINS AND SPREAD EASTWARD TONIGHT. LOW LEVEL WINDS THROUGH THE 850 MB LEVEL INCREASE TO 40-50 KNOTS OVERNIGHT WHICH SHOULD SUPPORT WIND ADVISORY CRITERIA WINDS LATER TONIGHT INTO THURSDAY MORNING. HAVE ISSUED A WIND ADVISORY FOR MIDNIGHT TONIGHT UNTIL NOON THURSDAY FOR ALL OF SOUTHWEST AND CENTRAL KANSAS. PRECIPITATION SHOULD BE WINDING DOWN FAIRLY QUICKLY LATE TONIGHT AND THURSDAY MORNING AS THE UPPER SYSTEM MOVES EAST OF THE REGION. CLOUDS SHOULD BE BREAKING UP FROM WEST TO EAST DURING THE DAY. WITH SOME SUN...AFTERNOON HIGH TEMPERATURES MAY BE ABLE TO CLIMB INTO THE LOWER 40S. .LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY) ISSUED AT 338 PM CDT WED APR 17 2013 FRIDAY: UPPER LEVEL WNW FLOW WILL CONTINUE ON FRIDAY. AT THE SURFACE, HIGH PRESSURE WILL RIDGE ACROSS THE PLAINS. NORTHWESTERLY WINDS WILL EVENTUALLY BECOME SOUTHERLY AFTER SUNSET. HIGHS WILL BE IN THE 50S AND LOWS WILL BE IN THE 20S. NO PRECIPITATION IS EXPECTED AS DRY FLOW ALOFT AND LACK OF BL MOISTURE CONTINUES. WEEKEND: AN UPPER LEVEL TROUGH WILL DIG ACROSS THE CENTRAL AND SOUTHERN ROCKIES THROUGH THE WEEKEND. THIS WILL PROMOTE A WARM AIR ADVECTION PATTERN DOWNSTREAM ACROSS OUR REGION. A WARM 850 HPA PLUME WILL ADVECT OFF THE ROCKIES AND OUT ACROSS SOUTHWEST KANSAS SATURDAY. THIS WILL FAVOR DEEP MIXING AND HIGHS IN THE UPPER 60S TO LOWER 70S. OVERNIGHT LOWS WILL MODERATE AS WELL WITH 30S ON SATURDAY AND 40S ON SUNDAY. TEMPERATURES AROUND 70 DEG F CAN BE EXPECTED SUNDAY AS THE AFOREMENTIONED WARM PLUME CONTINUES ACROSS THE REGION. THERE COULD BE A FEW SHOWERS ACROSS SC/S KANSAS IN ASSOCIATION WITH WARM ADVECTION BUT CONFIDENCE IS LOW AND MODELS ARE FAIRLY LIGHT ON QPF. NEXT WEEK AND BEYOND: A MAJOR CHANGE IN WEATHER IS POSSIBLE MONDAY OR TUESDAY. ANOTHER TROF DIGGING OUT OF THE NORTHERN ROCKIES WILL USHER IN THE PASSAGE OF A SIGNIFICANT COLD FRONT. THE ECMWF IS FAIRLY COLD WITH 850 HPA TEMPERATURES DECREASING DOWN TO -6 DEG C. BOTH THE GFS AND ECMWF INDICATE SOME LIGHT SNOWFALL ACROSS THE REGION ASSOCIATED WITH THIS FRONT. CONFIDENCE IS LOW FOR PRECIPITATION TYPE BUT THERE IS HIGHER CONFIDENCE IN LOWER TEMPERATURES WITH 40S AND 50S FOR HIGHS BY TUESDAY/WEDNESDAY. && .AVIATION...(FOR THE 00Z TAFS THROUGH 00Z THURSDAY EVENING) ISSUED AT 659 PM CDT WED APR 17 2013 POOR AVIATION CONDITIONS WILL CONTINUE THROUGH THE NIGHT AS A ROUND OF PRECIPITATION DEVELOPS THIS EVENING AND LINGERS THROUGH THE OVERNIGHT HOURS. THE PRECIPITATION TYPE WILL BE RAIN AT GCK, DDC, AND HYS THROUGH THE LATE EVENING...BUT A TRANSITION TO SLEET AND/OR SNOW IS EXPECTED LATE THIS EVENING AND ESPECIALLY AFTER MIDNIGHT. ONLY LIGHT PRECIPITATION IS EXPECTED, HOWEVER, AFTER MIDNIGHT SO NO ACCUMULATION OF SIGNIFICANCE IS EXPECTED. STRONG NORTH WINDS OF 25 OR MORE KNOTS WILL DEVELOP LATE AS THE MAIN UPPER LEVEL STORM SYSTEM APPROACHES. IFR CEILINGS WILL PREVAIL AT LEAST THROUGH THE MID MORNING HOURS THURSDAY...BUT GRADUALLY SCATTERING OUT TO VFR CONDITIONS THEREAFTER AS THE STORM EXITS THE WESTERN PLAINS. && .PRELIMINARY POINT TEMPS/POPS... DDC 27 38 24 59 / 70 10 0 0 GCK 27 37 22 60 / 60 10 0 0 EHA 26 39 23 60 / 40 10 0 0 LBL 28 41 23 60 / 50 10 0 0 HYS 28 36 23 58 / 80 30 0 0 P28 31 44 28 60 / 70 10 0 0 && .DDC WATCHES/WARNINGS/ADVISORIES... WIND ADVISORY UNTIL NOON CDT /11 AM MDT/ THURSDAY FOR KSZ030-031- 043>046-061>066-074>081-084>090. && $$ SYNOPSIS...HOVORKA_42 SHORT TERM...GERARD LONG TERM...SUGDEN AVIATION...UMSCHEID
AREA FORECAST DISCUSSION
NWS NORTH PLATTE NE
401 AM CDT THU APR 18 2013 .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 359 AM CDT THU APR 18 2013 THE PV1.5 ANOMALY CURRENTLY ACROSS WRN KS HAS SPAWNED ANOTHER LOCALLY STRONG BUT NARROW BAND OF MODERATE SNOW. THIS BAND OF SNOW WILL MOVE WITH THE ANOMALY AND THE RUC LIFTS IT NORTH NORTHEAST VERY QUICKLY THIS MORNING. ACCUMULATING SNOWFALL COULD BE OUT OF THE FCST BY 15Z AND HIGHEST ACCUMULATIONS...PERHAPS 4 INCHES...SHOULD FOCUS ALONG AND EAST OF HIGHWAY 281 INCLUDING CUSTER COUNTY. IT IS CLEAR THE DRY AIR IS WINNING OUT ON THIS SYSTEM AS THE SNOW HAS SHUT OFF WEST OF HIGHWAY 61 ACROSS WRN NEB. THE RAP IS SUGGESTING SOME SNOW SHOWER ACTIVITY TODAY AS THE 500 MB COLD POOL MOVES OVERHEAD...ESPECIALLY TO THE LEE OF THE BLACK HILLS WHERE A CONVERGENCE ZONE COULD DEVELOP. THE MODELS DO NOT FCST THE LOCATION OF CONVERGENCE VERY WELL BUT THE RAP...GEM REG AND NAM ARE SUGGESTING THE PANHANDLE SOUTH SOUTHEAST OF CHADRON. THE FCST TODAY JUST BROAD BRUSHES ISOLATED SNOW SHOWERS WEST BUT TAPERS THE SNOW OFF IN THE NORTHEAST. THE NAM AND RAP SHOW SKIES CLEARING AROUND NIGHTFALL TONIGHT. THE ARCTIC HIGH WILL BUILD THROUGH THE CNTL ROCKIES TONIGHT WHILE LOW PRESSURE SWIRLS ACROSS THE UPPER MIDWEST ALLOWING FOR WINDS TO STAY UP A BIT. THIS MIGHT HOLD LOWS NEAR 20 AND RADIATIONAL CONDITIONS WILL BE LESS THAN IDEAL. THE SNOW FCST IS FOR 1 TO 3 INCHES OF NEW SNOW TODAY. THIS USES THE RUC QPF BUT REDUCES IT BY 70 PERCENT IN MOST AREAS AND APPLIES A 10 TO 1 RATIO. THIS IS THE SAME AS REDUCING THE QPF BY 50 PERCENT AND USING A 14 TO 1 RATIO WHICH MIGHT BE CLOSER TO REAL LIFE. .LONG TERM...(FRIDAY THROUGH WEDNESDAY) ISSUED AT 359 AM CDT THU APR 18 2013 FRIDAY WILL SEE HIGHS REBOUND BACK INTO THE 40S...NEAR 50 FOR FAR SW NEB. HOWEVER NORTHWEST FLOW WILL BRING A DISTURBANCE ACROSS THE NORTHERN PLAINS. MODELS SHOW SOME DECENT LOW LEVEL SATURATION...WITH DRY AIR ALOFT. COULD SEE SOME DRIZZLE OR SPRINKLES DURING THE DAY...HOWEVER JUST NOT ENOUGH CONFIDENCE TO ADD YET...MAINLY DUE TO CURRENT CONDITIONS ON THE DRIER SIDE. SATURDAY AND SUNDAY THE COUPLE MORE OF QUICK MOVING DISTURBANCES WILL RIDE ACROSS NORTHERN/CENTRAL PLAINS. BETTER ENERGY IS TO THE NORTH...HOWEVER WILL SEE THE SOUTHERN EDGE MOVE ACROSS THE CWA. EXPECTING TO CONTINUE TO SEE COLD AIR ALOFT SPREAD DOWN FROM CANADA...HOWEVER LESS MOISTURE TO WORK WITH IN THE LOWER LEVELS. STRONGER COLD FRONT SUNDAY WITH GFS DEVELOPING SOME MARGINAL CAPE...COUPLE HUNDRED J/KG...AND BARELY NEG LI/S AHEAD OF THE FRONT. HAVE INTRODUCED ISOLD THUNDER DURING THE DAY...WHICH MAY LINGER INTO THE EVENING DEPENDING ON EXACT TIMING OF THE FRONT AND MOISTURE. MONDAY AND TUESDAY ARE EXPECTED TO BE ANOTHER WELL BELOW NORMAL COUPLE OF DAYS. GFS CAME IN COOLER...WHICH IS CLOSER TO THE COOLER EC. HIGHS LIKELY IN THE 40S...WHICH WOULD NORMALLY BE A STRETCH TO GO SO FAR BELOW NORMAL /NORMAL IS 60S/ THIS FAR OUT. HOWEVER WITH THE LAST TWO SYSTEMS SHOWING HOW EASY IT IS TO ACCOMPLISH THIS APRIL...WILL CONTINUE TO BE SOME 20 PLUS DEGREES BELOW NORMAL FOR HIGHS. LOWS IN THE 20S SO LIGHT PRECIP IS EXPECTED TO BE RAIN OR A MIX DURING THE DAY AND A MIX TO SNOW OVERNIGHT. WEDNESDAY WILL SEE THE START OF ANOTHER WARMUP AND DRY CONDITIONS. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT) ISSUED AT 1227 AM CDT THU APR 18 2013 MIXED IFR/MVFR/VFR CONTINUES OVERNIGHT WITH IMPROVEMENT TO VFR/MVFR FROM WEST TO EAST. THIS PROCESS IS ALREADY UNDERWAY ACROSS WRN NEB. THE RAP IS SUGGESTING LOCAL IFR ACROSS WRN NEB THURSDAY AFTERNOON AS SCATTERED -SHSN DEVELOP. EAST OF HIGHWAY 83...IFR/MVFR MAY CONTINUE THROUGH THURSDAY AFTERNOON IN SNOW AND BLSN. IMPROVEMENT TO WIDESPREAD VFR IS EXPECTED ALL AREAS BETWEEN 00Z THURSDAY AND 06Z THURSDAY EVENING AS THE UPPER LEVEL LOW ACROSS THE SRN ROCKIES EJECTS INTO THE MIDWEST. && .LBF WATCHES/WARNINGS/ADVISORIES... WINTER WEATHER ADVISORY UNTIL 4 PM CDT THIS AFTERNOON FOR NEZ006>010-026>029-038. && $$ SHORT TERM...CDC LONG TERM...MASEK AVIATION...CDC
AREA FORECAST DISCUSSION
NWS NORTH PLATTE NE
1253 AM CDT THU APR 18 2013 .SYNOPSIS... ISSUED AT 256 PM CDT WED APR 17 2013 AT 19Z...WATER VAPOR IMAGERY CONTINUED SHOWING A DEEP TROUGH ACROSS THE WESTERN STATES WITH THE AXIS RUNNING FROM LAKE WINNIPEG THROUGH MONTANA...WYOMING AND UTAH TO SOUTHERN NEVADA. AT THE SURFACE...THERE WAS A STRENGTHENING SURFACE LOW OVER CENTRAL NEW MEXICO. A FRONT EXTENDED FROM THAT LOW ACROSS THE TEXAS RED RIVER AREA THROUGH EASTERN OKLAHOMA AND SOUTHEAST KANSAS TO CENTRAL MISSOURI. THERE WAS ALSO AND INVERTED TROUGH OR OCCLUDED FRONT EXTENDING FROM THE NEW MEXICO LOW INTO SOUTH CENTRAL COLORADO. && .UPDATE... ISSUED AT 1252 AM CDT THU APR 18 2013 DRY AIR HAS MADE RAPID PROGRESS THROUGH WESTERN NEB SO SEVERAL COUNTIES CAN BE CLEARED FROM THE WINTER WEATHER ADVISORY. SNOW SHOWER ACTIVITY IS EXPECTED OVERNIGHT THROUGH THURSDAY AFTN BUT WIND SPEEDS AND SNOW ACCUMULATIONS WOULD NOT WARRANT AN ADVISORY. UPDATE ISSUED AT 948 PM CDT WED APR 17 2013 A NEW FORECAST IS OUT USING THE RAP AND ARF MODELS. STILL LOOKS LIKE AREAS EAST OF HIGHWAY 83 WILL MEASURE 3 TO 6 INCHES BY THURSDAY AFTN. WEST OF 83...THE SNOW IS SHOWING SIGNS OF WINDING DOWN. SATELLITE AND THE RAP MODEL SHOW TO DISTINCT AREAS OF POTENTIAL VORTICITY. ONE NEAR DODGE CITY WHICH IS IGNITING CONVECTION. SLEET AND SNOW SHOULD DEVELOP AS THIS AREA MOVES NORTH NORTHEAST BRUSHING EASTERN ZONES WITH SNOW AFTER MIDNIGHT. MOST OF THIS SNOW SHOULD END UP ACROSS CNTL NEB. THE SECOND AREA OF POTENTIAL VORTICITY LIES ACROSS ERN NEW MEXICO. THIS ARE IS EXPECTED TO IGNITE A SECOND BAND OF MODERATE SNOW ALONG AND EAST OF HIGHWAY 83 LATE TONIGHT AND THURSDAY. MOST OF THIS SNOW SHOULD FALL EAST OF HIGHWAY 83. THUS 2 TO 4 INCHES IS EXPECTED WEST OF HIGHWAY 83 WITH THE EMPHASIS ON 2 INCHES GIVEN THE RADAR TRENDS AND SIGNS OF DRY AIR WORKING SOUTHWARD THROUGH SOUTH DAKOTA. WINDS ARE ABOUT 10 KTS LESS THAN PREVIOUSLY FORECAST BUT STRONGEST WINDS COULD DEVELOP LATE THURSDAY MORNING AND AFTERNOON. THE REST OF THE FORECAST IS ON TRACK. && .SHORT TERM...(THIS EVENING THROUGH THURSDAY) ISSUED AT 256 PM CDT WED APR 17 2013 AREAS OF FREEZING DRIZZLE THIS MORNING LOOKS TO BE TRANSITIONING MORE TO LIGHT FOG AND VERY LIGHT SNOW ACROSS THE CENTRAL SANDHILLS AND EASTERN AREAS THIS AFTERNOON AS COLDER AIR CONTINUES TO SETTLE SOUTHWARD. ONLY AREA WITH LIGHT SNOW ACCUMULATIONS THIS AFTERNOON IS ACROSS SHERIDAN AND NORTHWEST CHERRY COUNTY. THE 700MB CLOSED LOW WAS LOCATED IN CENTRAL COLORADO AT 18Z TODAY. SNOW EXTENDS ACROSS THE COLORADO MOUNTAINS AND EASTERN FOOTHILLS INTO SOUTHEAST WYOMING THE NEBRASKA PANHANDLE AND SOUTHWEST SOUTH DAKOTA. MEANWHILE SHOWERS AND THUNDERSTORMS HAVE DEVELOPED ACROSS CENTRAL AND NORTHEAST KANSAS INTO FAR SOUTHEAST NEBRASKA SOUTHWEST IOWA. STRONG STORMS DEVELOPING WEST CENTRAL OKLAHOMA/SOUTH CENTRAL KANSAS. THE UPPER LOW IS FORECAST TO LIFT NORTHEAST AS A POSITIVELY TILT INTO NORTHWEST KANSAS/CENTRAL NEBRASKA BY 06Z THURSDAY. MODERATE TO LOCALLY HEAVY SNOW IS FAVORED TO DEVELOP ALONG AND WEST OF THE UPPER LOW. THE GFS IS AND HAS CONSISTENTLY BEEN MORE ROBUST WITH QPFS THE PAST SEVERAL RUNS...WHILE THE NAM HAS SLOWLY BEEN COMING INTO LINE. ONE CONCERN WILL BE CONVECTION TO OUR SOUTHEAST THIS AFTERNOON/TONIGHT WHICH MAY LIMIT MOISTURE TRANSPORT INTO WESTERN NEBRASKA TONIGHT INTO THURSDAY. HAVE TAKEN THIS INTO ACCOUNT WITH THE FORECAST. SECOND CONCERN WILL BE WINDS WITH NORTH WINDS THIS EVENING 20 TO 35 MPH BACKING TO THE NORTHWEST AFTER MIDNIGHT. THEN ON THURSDAY...NORTHWEST WINDS TO INCREASE TO 25 TO 35 MPH WITH GUSTS TO 40 MPH. WINDS TONIGHT AND THURSDAY WILL CAUSE BLOWING AND DRIFTING SNOW ACROSS THE SOUTHERN AND EASTERN HALF OF THE AREA THROUGH THURSDAY. IN THE WINTER WEATHER ADVISORY AREA...SNOWFALL AMOUNTS TONIGHT AND THURSDAY RANGE FROM 3 TO 5 INCHES SOUTHWEST NEBRASKA...4 TO 7 INCHES EAST OF VALENTINE THROUGH BROKEN BOW. ACROSS THE NORTHWEST AROUND 6 INCHES POSSIBLE. WILL CARRY ALL EXISTING WINTER STORM WARNINGS AND ADVISORY THROUGH TONIGHT. ONLY CHANGE WAS TO EXTEND THE ADVISORY THROUGH THE DAY THURSDAY ACROSS THE EASTERN HALF OF THE FORECAST AREA DUE TO THE SLOWER TIMING OF THE SYSTEM AND EXPECTED WRAP AROUND SNOW. THE STRONG NORTHWEST WINDS WITH HIGH TEMPERATURES ONLY IN THE LOWER 30S MOST AREAS THURSDAY TO RESULT IN WIND CHILL VALUES OF 5 TO 15 ABOVE IN THE MORNING AND 15 TO 20 DEGREES IN THE AFTERNOON. .LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY) ISSUED AT 256 PM CDT WED APR 17 2013 WARM AIR RETURNING FROM THE SOUTHWEST FRIDAY EVENING WILL GENERATE SOME DEEP ISENTROPIC UPGLIDE OF NEARLY SATURATED AIR IN THE 290-310K LAYER. THE BOUNDARY LAYER IS PRETTY DRY THOUGH...SO SIGNIFICANT PRECIPITATION IS NOT LIKELY. A FRONT SETTLES INTO THE NORTHERN PLAINS SATURDAY AND THEN BEGINS MOVING NORTH AND SOUTH ALTERNATELY. THIS WILL KEEP SOME CHANCE OF PRECIPITATION IN CENTRAL AND WESTERN NEBRASKA SATURDAY EVENING THROUGH TUESDAY. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT) ISSUED AT 1227 AM CDT THU APR 18 2013 MIXED IFR/MVFR/VFR CONTINUES OVERNIGHT WITH IMPROVEMENT TO VFR/MVFR FROM WEST TO EAST. THIS PROCESS IS ALREADY UNDERWAY ACROSS WRN NEB. THE RAP IS SUGGESTING LOCAL IFR ACROSS WRN NEB THURSDAY AFTERNOON AS SCATTERED -SHSN DEVELOP. EAST OF HIGHWAY 83...IFR/MVFR MAY CONTINUE THROUGH THURSDAY AFTERNOON IN SNOW AND BLSN. IMPROVEMENT TO WIDESPREAD VFR IS EXPECTED ALL AREAS BETWEEN 00Z THURSDAY AND 06Z THURSDAY EVENING AS THE UPPER LEVEL LOW ACROSS THE SRN ROCKIES EJECTS INTO THE MIDWEST. && .LBF WATCHES/WARNINGS/ADVISORIES... WINTER WEATHER ADVISORY UNTIL 7 AM CDT /6 AM MDT/ THIS MORNING FOR NEZ024-036-058-069-070. WINTER WEATHER ADVISORY UNTIL 1 PM CDT THIS AFTERNOON FOR NEZ005- 025-037-059-071. WINTER WEATHER ADVISORY UNTIL 7 PM CDT THIS EVENING FOR NEZ006>010-026>029-038. && $$ UPDATE...CDC SYNOPSIS...SPRINGER SHORT TERM...ROBERG LONG TERM...SPRINGER AVIATION...CDC
AREA FORECAST DISCUSSION...UPDATED
NWS NORTH PLATTE NE
948 PM CDT WED APR 17 2013 .SYNOPSIS... ISSUED AT 256 PM CDT WED APR 17 2013 AT 19Z...WATER VAPOR IMAGERY CONTINUED SHOWING A DEEP TROUGH ACROSS THE WESTERN STATES WITH THE AXIS RUNNING FROM LAKE WINNIPEG THROUGH MONTANA...WYOMING AND UTAH TO SOUTHERN NEVADA. AT THE SURFACE...THERE WAS A STRENGTHENING SURFACE LOW OVER CENTRAL NEW MEXICO. A FRONT EXTENDED FROM THAT LOW ACROSS THE TEXAS RED RIVER AREA THROUGH EASTERN OKLAHOMA AND SOUTHEAST KANSAS TO CENTRAL MISSOURI. THERE WAS ALSO AND INVERTED TROUGH OR OCCLUDED FRONT EXTENDING FROM THE NEW MEXICO LOW INTO SOUTH CENTRAL COLORADO. && .UPDATE... ISSUED AT 948 PM CDT WED APR 17 2013 A NEW FORECAST IS OUT USING THE RAP AND ARF MODELS. STILL LOOKS LIKE AREAS EAST OF HIGHWAY 83 WILL MEASURE 3 TO 6 INCHES BY THURSDAY AFTN. WEST OF 83...THE SNOW IS SHOWING SIGNS OF WINDING DOWN. SATELLITE AND THE RAP MODEL SHOW TO DISTINCT AREAS OF POTENTIAL VORTICITY. ONE NEAR DODGE CITY WHICH IS IGNITING CONVECTION. SLEET AND SNOW SHOULD DEVELOP AS THIS AREA MOVES NORTH NORTHEAST BRUSHING EASTERN ZONES WITH SNOW AFTER MIDNIGHT. MOST OF THIS SNOW SHOULD END UP ACROSS CNTL NEB. THE SECOND AREA OF POTENTIAL VORTICITY LIES ACROSS ERN NEW MEXICO. THIS ARE IS EXPECTED TO IGNITE A SECOND BAND OF MODERATE SNOW ALONG AND EAST OF HIGHWAY 83 LATE TONIGHT AND THURSDAY. MOST OF THIS SNOW SHOULD FALL EAST OF HIGHWAY 83. THUS 2 TO 4 INCHES IS EXPECTED WEST OF HIGHWAY 83 WITH THE EMPHASIS ON 2 INCHES GIVEN THE RADAR TRENDS AND SIGNS OF DRY AIR WORKING SOUTHWARD THROUGH SOUTH DAKOTA. WINDS ARE ABOUT 10 KTS LESS THAN PREVIOUSLY FORECAST BUT STRONGEST WINDS COULD DEVELOP LATE THURSDAY MORNING AND AFTERNOON. THE REST OF THE FORECAST IS ON TRACK. && .SHORT TERM...(THIS EVENING THROUGH THURSDAY) ISSUED AT 256 PM CDT WED APR 17 2013 AREAS OF FREEZING DRIZZLE THIS MORNING LOOKS TO BE TRANSITIONING MORE TO LIGHT FOG AND VERY LIGHT SNOW ACROSS THE CENTRAL SANDHILLS AND EASTERN AREAS THIS AFTERNOON AS COLDER AIR CONTINUES TO SETTLE SOUTHWARD. ONLY AREA WITH LIGHT SNOW ACCUMULATIONS THIS AFTERNOON IS ACROSS SHERIDAN AND NORTHWEST CHERRY COUNTY. THE 700MB CLOSED LOW WAS LOCATED IN CENTRAL COLORADO AT 18Z TODAY. SNOW EXTENDS ACROSS THE COLORADO MOUNTAINS AND EASTERN FOOTHILLS INTO SOUTHEAST WYOMING THE NEBRASKA PANHANDLE AND SOUTHWEST SOUTH DAKOTA. MEANWHILE SHOWERS AND THUNDERSTORMS HAVE DEVELOPED ACROSS CENTRAL AND NORTHEAST KANSAS INTO FAR SOUTHEAST NEBRASKA SOUTHWEST IOWA. STRONG STORMS DEVELOPING WEST CENTRAL OKLAHOMA/SOUTH CENTRAL KANSAS. THE UPPER LOW IS FORECAST TO LIFT NORTHEAST AS A POSITIVELY TILT INTO NORTHWEST KANSAS/CENTRAL NEBRASKA BY 06Z THURSDAY. MODERATE TO LOCALLY HEAVY SNOW IS FAVORED TO DEVELOP ALONG AND WEST OF THE UPPER LOW. THE GFS IS AND HAS CONSISTENTLY BEEN MORE ROBUST WITH QPFS THE PAST SEVERAL RUNS...WHILE THE NAM HAS SLOWLY BEEN COMING INTO LINE. ONE CONCERN WILL BE CONVECTION TO OUR SOUTHEAST THIS AFTERNOON/TONIGHT WHICH MAY LIMIT MOISTURE TRANSPORT INTO WESTERN NEBRASKA TONIGHT INTO THURSDAY. HAVE TAKEN THIS INTO ACCOUNT WITH THE FORECAST. SECOND CONCERN WILL BE WINDS WITH NORTH WINDS THIS EVENING 20 TO 35 MPH BACKING TO THE NORTHWEST AFTER MIDNIGHT. THEN ON THURSDAY...NORTHWEST WINDS TO INCREASE TO 25 TO 35 MPH WITH GUSTS TO 40 MPH. WINDS TONIGHT AND THURSDAY WILL CAUSE BLOWING AND DRIFTING SNOW ACROSS THE SOUTHERN AND EASTERN HALF OF THE AREA THROUGH THURSDAY. IN THE WINTER WEATHER ADVISORY AREA...SNOWFALL AMOUNTS TONIGHT AND THURSDAY RANGE FROM 3 TO 5 INCHES SOUTHWEST NEBRASKA...4 TO 7 INCHES EAST OF VALENTINE THROUGH BROKEN BOW. ACROSS THE NORTHWEST AROUND 6 INCHES POSSIBLE. WILL CARRY ALL EXISTING WINTER STORM WARNINGS AND ADVISORY THROUGH TONIGHT. ONLY CHANGE WAS TO EXTEND THE ADVISORY THROUGH THE DAY THURSDAY ACROSS THE EASTERN HALF OF THE FORECAST AREA DUE TO THE SLOWER TIMING OF THE SYSTEM AND EXPECTED WRAP AROUND SNOW. THE STRONG NORTHWEST WINDS WITH HIGH TEMPERATURES ONLY IN THE LOWER 30S MOST AREAS THURSDAY TO RESULT IN WIND CHILL VALUES OF 5 TO 15 ABOVE IN THE MORNING AND 15 TO 20 DEGREES IN THE AFTERNOON. .LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY) ISSUED AT 256 PM CDT WED APR 17 2013 WARM AIR RETURNING FROM THE SOUTHWEST FRIDAY EVENING WILL GENERATE SOME DEEP ISENTROPIC UPGLIDE OF NEARLY SATURATED AIR IN THE 290-310K LAYER. THE BOUNDARY LAYER IS PRETTY DRY THOUGH...SO SIGNIFICANT PRECIPITATION IS NOT LIKELY. A FRONT SETTLES INTO THE NORTHERN PLAINS SATURDAY AND THEN BEGINS MOVING NORTH AND SOUTH ALTERNATELY. THIS WILL KEEP SOME CHANCE OF PRECIPITATION IN CENTRAL AND WESTERN NEBRASKA SATURDAY EVENING THROUGH TUESDAY. && .AVIATION...(FOR THE 00Z TAFS THROUGH 00Z THURSDAY EVENING) ISSUED AT 623 PM CDT WED APR 17 2013 MVFR/IFR CONTINUES TONIGHT IN FREEZING RAIN...SLEET AND SNOW. THE FORECAST MODELS SUGGEST A GRADUAL CEILING IMPROVEMENT ALONG AND WEST OF HIGHWAY 83 AFTER 18Z THURSDAY. THUS MVFR AND VFR CIGS COULD DEVELOP WEST OF 83 TOMARROW AFTN. EAST OF 83...MVFR/IFR IS EXPECTED TO CONTINUE THROUGHOUT THE DAY THURSDAY IN SNOW AND BLOWING SNOW. && .LBF WATCHES/WARNINGS/ADVISORIES... WINTER WEATHER ADVISORY UNTIL 7 AM CDT /6 AM MDT/ THURSDAY FOR NEZ004-022>024-035-036-056>058-069-070-094. WINTER WEATHER ADVISORY UNTIL 1 PM CDT THURSDAY FOR NEZ005-025- 037-059-071. WINTER WEATHER ADVISORY UNTIL 7 PM CDT THURSDAY FOR NEZ006>010- 026>029-038. && $$ UPDATE...CDC SYNOPSIS...SPRINGER SHORT TERM...ROBERG LONG TERM...SPRINGER AVIATION...CDC
AREA FORECAST DISCUSSION
NWS ALBUQUERQUE NM
943 PM MDT WED APR 17 2013 .UPDATE... EXPIRED THE WIND RELATED NPW PRODUCTS ON SCHEDULE AND CANCELLED THE EAST CENTRAL ZONES WIND ADVISORY THAT WAS OUT ALL NIGHT... THOUGH THE LATTER IS A RATHER CLOSE CALL FOR THE CLOVIS AREA AS THAT OBSERVATION OFTEN SEEMS AT THE HIGH END OF WIND SPEEDS COMPARED TO SURROUNDING AREAS. STILL DO NOT BELIEVE ADVISORY LVL SPEEDS WILL BE REPRESENTATIVE FOR THE MAJORITY OF THOSE CANCELLED COUNTIES. HAVE SOME CONCERN FOR HOW LONG DURATION OF FREEZING TEMPS WILL BE LATE TONIGHT FOR MOST OF THE FREEZE WARNING ZONES AS EITHER CLOUDS OR WIND MAY HOLD THEM UP A BIT HIGHER THAN EARLIER EXPECTED...SO IT MAY BE RATHER MARGINAL FOR TONIGHT. KEPT THE HIGHLIGHTS GOING HOWEVER AS RECENT WARMTH WILL LIKELY HAVE LURED SOME GARDENERS TO PLANT SENSITIVE PLANTS ALREADY. AS FOR SNOW ADVISORY...IT APPEARS THAT EXPIRATION TIME IS OUT TOO LONG IN TIME...ESPECIALLY FOR HARDING AND UNION COUNTIES. TEMPS GETTING BACK WELL ABOVE FREEZING...LESSENING UPSLOPE FLOW AND EVEN MORE LIMITED MOISTURE AND DYNAMICS WITH NEXT FOLLOWUP DISTURBANCE IN NW FLOW WOULD ARGUE FOR SIGNIFICANTLY EARLIER EXPIRATION TIME...AND EVEN THE NORTHERN MTN ZONES WILL LIKELY SEE JUST OFF AND ON SNOW SHOWERS THAT WILL NOT ACCUM MUCH IF AT ALL GIVEN THAT IT IS THIS LATE IN APRIL AND THERE WOULD BE SOME MELTING OF ANY MINOR ACCUM. ANY SNOW SHOWERS WOULD BRING. NONETHELESS...AM DEFERRING TO MIDNIGHT CREW TO MAKE THAT DETERMINATION GIVEN LATEST MODEL AND OTHER INDICATIONS. 43 && .PREV DISCUSSION...536 PM MDT WED APR 17 2013... .AVIATION... 00Z TAF CYCLE LOW CLOUDS WILL SURGE SOUTH AGAIN TONIGHT AS A POTENT BACK DOOR COLD FRONT SURGES INTO THE EASTERN PLAINS. LATEST RUC AND NAM SOLUTIONS INDICATE LOW CLOUDS NEAR 015 WILL MAKE IT BACK INTO KTCC AND SATELLITE CONFIRMS...SO HAVE ADDED BKN CIGS THERE FOR SEVERAL HOURS TONIGHT. SOME LIGHT PRECIP MAY DEVELOP BEHIND THE FRONT AS WELL HOWEVER LEFT OUT SINCE CONFIDENCE NOT AS HIGH. MODELS BOTH AGREE AS WELL WITH FRONT PUSHING INTO KROW WITH A SCT TO BKN DECK BUT NOT NEARLY AS CONFIDENCE THERE SO LEFT SCT DECK FOR NOW. ELSEWHERE...WINDS AND BLDU WILL TAPER OFF THIS EVENING. PRECIP WILL BECOME TERRAIN DOMINATED OVER THE NORTH WHERE A COUPLE INCHES OF SNOW AND IFR CIGS WILL OCCUR. THE MAIN IMPACT AREA FOR SNOW WILL BE THE NE PLAINS FROM RATON EAST TO CLAYTON. SKIES WILL CLEAR THURSDAY FROM WEST TO EAST...EXCEPT FOR THE NE CORNER WHERE MODELS CONTINUE TO INDICATE SOME LIGHT PRECIP PUSHING EAST OFF THE HIGH TERRAIN. GUYER .PREV DISCUSSION...330 PM MDT WED APR 17 2013... PLETHORA OF HIGHLIGHTS OUT SO WILL KEEP THIS SHORT. UPPER LEVEL LOW/TROUGH NEAR THE FOUR CORNERS EARLY THIS AFTERNOON. RELATIVELY MOIST SOUTHWEST FLOW ALOFT CONTINUING TO BRING OCCASIONAL LIGHT TO MODERATE SNOW TO PORTIONS OF THE NORTHERN MOUNTAINS. LIGHT ACCUMULATION REPORTED IN CHAMA AND DULCE BY LATE THIS MORNING WITH LIGHT SNOW AND A TRACE OF ACCUMULATION AT ANGEL FIRE. BACKDOOR FRONT REMAINED NEARLY STATIONARY TODAY...FROM NEAR A TRINIDAD TO RATON TO TUCUMCARI LINE. APPROXIMATELY A 40F DIFFERENCE BETWEEN THE AIRMASS TO THE NORTH OF THE FRONT OVER NE NM AND THE AIRMASS OVER SE NM. UPPER LOW/TROUGH WILL CONTINUE TO SLOWLY TRANSLATE EWD THIS EVENING...WITH THE TROUGH AXIS LOCATED ALONG INTERSTATE 25 OR SO BY AROUND MIDNIGHT. NAM AND GFS IN GOOD AGREEMENT THAT AS THE 700MB WAVE CROSSES THE ROCKIES EARLY THIS EVENING...THE MID LEVEL FLOW TURNS NORTHERLY AND THE COLD AIR OVER ERN COLORADO/BACKDOOR FRONT SURGES SOUTHWARD OVERNIGHT. DECIDED TO INCLUDE THE FAR NE HIGHLANDS...UNION AND HARDING COUNTIES IN THE WINTER WEATHER ADVISORY OVERNIGHT. 12Z NAM12 HITTING THIS AREA QUITE HARD WITH SNOW THIS EVENING AND WITH VISIBLE SATELLITE IMAGERY SHOWING SIGNS OF STRONG FRONTOGENETIC FORCING ALONG WITH MID-LEVEL INSTABILITY OVER NE NM/SE CO STARTING TO TAKE SHAPE. UPPER LEVEL TROUGH SLOW TO SHIFT EWD THURSDAY WITH ONE LAST SPEED MAX TO ROUND THE BASE OF THE TROUGH. SURFACE CONVERGENCE ALONG WITH COLD AIR ALOFT WILL LEAD TO SCATTERED SNOW SHOWERS FOR THE NORTHERN MOUNTAINS DURING THE AFTERNOON. DRY NW FLOW ALOFT TRANSITIONS OVERHEAD THURSDAY NIGHT AND FRIDAY. WARMING TREND GETS UNDERWAY AREA-WIDE FRIDAY WITH TEMPERATURES STARTING TO AT LEAST APPROACH AVERAGE LEVELS. THE WARMING TREND CONTINUES INTO THE WEEKEND...ALBEIT A WEAK SHORT-WAVE CLIPS THE FAR NORTH/NE PART OF THE STATE SLOWING THE WARMING TREND THERE WITH A SLIGHT CHANCE FOR A LIGHT MOUNTAIN SHOWER. MEDIUM RANGE GLOBAL MODELS SEEM TO BE SETTLING ON TIMING AND PLACEMENT OF THE NEXT COLD UPPER LEVEL TROUGH AND UNSEASONABLY STRONG BACK DOOR COLD FRONT FOR EARLY NEXT WEEK. 33 .FIRE WEATHER... STRONG SURFACE WINDS AND RELATIVE HUMIDITY BELOW 15 PERCENT WILL CONTINUE TO PRODUCE RED FLAG CONDITIONS THROUGH MID EVENING ACROSS ZONES 106...107 AND 108. STRONGEST WINDS WILL DIMINISH AFTER THAT TIME AND LESSEN THE FIRE WEATHER CONDITIONS. BASE OF UPPER LEVEL LOW WILL MOVE ACROSS NORTHERN NM TONIGHT...WHILE A COLD FRONT PUSHES SOUTHWARD ACROSS EASTERN NM. THESE TWO SYSTEMS WILL PRODUCE LIGHT TO OCCASIONALLY MODERATE SNOWFALL ACROSS THE NORTHERN SANGRE DE CRISTOS...THE NORTHERN HIGHLANDS AND THE FAR NORTHEASTERN PLAINS. WETTING PRECIPITATION IS LIKELY ACROSS THESE AREAS TONIGHT. INCREASING LOW LEVEL MOISTURE TONIGHT WILL PRODUCE VERY GOOD TO EXCELLENT RECOVERIES ACROSS THE NORTHERN MOUNTAINS AND EASTERN PLAINS. FAIR TO GOOD OVERNIGHT RECOVERIES ARE EXPECTED ACROSS THE REMAINDER OF THE REGION. WINDS WILL DROP BELOW 15 MPH ACROSS MOST OF THE REGION AFTER MIDNIGHT...EXCEPT BEHIND THE COLD FRONT IN THE EASTERN PLAINS. A WIND ADVISORY WILL REMAIN IN EFFECT ACROSS THE EASTERN PLAINS THROUGH DAWN THURSDAY WITH NORTH TO NORTHEAST WINDS GREATER THAN 30 MPH. AS THE UPPER LOW MOVES AWAY FROM NM INTO THE U.S. CENTRAL PLAINS THURSDAY...A DEEP NORTHWEST FLOW WILL SET UP ACROSS THE STATE. NORTHWEST WIND WEST OF THE DIVIDE WILL GUST TO 30 MPH IN THE AFTERNOON...BUT RELATIVE HUMIDITY WILL REMAIN ABOVE CRITICAL VALUES. RELATIVE HUMIDITY ACROSS THE SOUTHERN ZONES WILL DIP BRIEFLY BELOW 15 PERCENT...BUT WIND SPEEDS AND GUSTS ACROSS THIS AREA WILL BE LIGHTER. VENTILATION THURSDAY WILL BE VERY GOOD WEST OF THE DIVIDE AND GOOD EAST OF THE DIVIDE. SURFACE HIGH PRESSURE TO THE NORTH WILL BEGIN TO BUILD SOUTHWARD ACROSS NM THURSDAY NIGHT...AND LIGHT NORTH TO NORTHWEST WINDS ARE EXPECTED. EXPECT INVERSIONS TO DEVELOP IN THE VALLEY AND LOW-LYING AREAS LATE THURSDAY NIGHT. RECOVERIES WILL BE FAIR TO GOOD IN MOST LOCATIONS AND WILL BE VERY GOOD TO EXCELLENT ACROSS NORTHERN NM. WEAK HIGH PRESSURE ALOFT AND MODERATE SURFACE HIGH PRESSURE WILL BUILD ACROSS NM FRIDAY. THIS WEATHER PATTERN WILL PRODUCE LIGHT WINDS FOR THE ENTIRE REGION WITH GUSTS GENERALLY LESS THAN 20 MPH IN THE AFTERNOON. MORNING INVERSIONS WILL BE SLOW TO BURN OFF FRIDAY...ESPECIALLY WEST OF THE DIVIDE. SIGNIFICANTLY DRIER AIR WILL MOVE ACROSS NM FROM THE WEST FRIDAY. THIS AIR MASS WILL CAUSE AFTERNOON RELATIVE HUMIDITY TO FALL BELOW 15 PERCENT IN MOST LOCATIONS...EXCEPT IN THE NORTHERN MOUNTAINS. VENTILATION WILL BE POOR TO FAIR DURING THE MORNING HOURS...AND THEN IMPROVE TO GOOD TO VERY GOOD IN THE AFTERNOON. DRY AIR MASS WILL REMAIN IN PLACE ACROSS NM FRIDAY NIGHT. OVERNIGHT RELATIVE HUMIDITY RECOVERIES WILL BE POOR TO FAIR...EXCEPT IN THE NORTHERN MOUNTAINS...WHERE RECOVERIES ARE EXPECTED TO BE GOOD. WINDS WILL BE LIGHT WEST OF THE DIVIDE FRIDAY NIGHT. SURFACE LOW PRESSURE FORMING IN EASTERN CO FRIDAY NIGHT WILL GENERATE LIGHT TO MODERATE SOUTH TO SOUTHEAST WINDS IN THE EASTERN PLAINS. RECOVERIES WILL BE POOR ACROSS SOUTH CENTRAL ZONES AND FAIR ELSEWHERE. A COMBINATION OF DEVELOPING SURFACE LOW PRESSURE ACROSS WESTERN TX AND STRENGTHENING WINDS ALOFT SATURDAY WILL AN INCREASE IN WIND SPEEDS EAST OF THE DIVIDE. AFTERNOON WINDS EAST OF THE DIVIDE WILL GUST UP TO 35 MPH IN THE AFTERNOON HOURS. LOW RELATIVE HUMIDITY AND GUSTY WINDS HAVE THE POTENTIAL TO CREATE 3 TO 5 HOURS OF NEAR CRITICAL FIRE WEATHER CONDITIONS ALONG I-40 FROM CLINES CORNERS TO SANTA ROSA SATURDAY AFTERNOON. VENTILATION WILL BE FAIR TO GOOD IN THE MORNING HOURS AND RAPIDLY IMPROVE IN THE EARLY AFTERNOON TO BECOME EXCELLENT ACROSS ALL OF NM. && .ABQ WATCHES/WARNINGS/ADVISORIES... HARD FREEZE WATCH FROM THURSDAY EVENING THROUGH FRIDAY MORNING FOR THE FOLLOWING ZONES...NMZ519-520-530>538. FREEZE WARNING FROM 2 AM TO 10 AM MDT THURSDAY FOR THE FOLLOWING ZONES...NMZ519-520-534>536. WINTER WEATHER ADVISORY UNTIL 6 PM MDT THURSDAY FOR THE FOLLOWING ZONES...NMZ510-512>515-527-528-530-531. && $$ 43
AREA FORECAST DISCUSSION
NWS WILMINGTON OH
143 AM EDT THU APR 18 2013 .SYNOPSIS... A POTENT SPRING STORM SYSTEM WILL EJECT NORTHEAST THROUGH THE MID MISSISSIPPI VALLEY TONIGHT THROUGH FRIDAY...BRINGING A WILD SWING IN TEMPERATURE AND THE THREAT OF STRONG TO SEVERE THUNDERSTORMS. VERY WARM CONDITIONS ON THURSDAY WITH GUSTY SOUTH WINDS WILL BE FOLLOWED BY EVEN GUSTIER NORTHWEST WINDS AND TEMPERATURES SOME 30 DEGREES LOWER THAN THAN ON THURSDAY. IN THE WAKE OF THIS SYSTEM...COOL CANADIAN HIGH PRESSURE WILL SETTLE INTO THE OHIO VALLEY FOR THE WEEKEND WITH THE THREAT OF MORNING FROST AND SOME DRY WEATHER. && .NEAR TERM /UNTIL 6 AM THIS MORNING/... WARM FRONTAL BOUNDARY WILL CONTINUE TO LIFT NORTH THROUGH THE OVERNIGHT HOURS. MOST LOCATIONS WILL REMAIN DRY THROUGH THE OVERNIGHT HOURS HOWEVER A FEW ISOLATED STORMS MAY REACH INTO NW PORTIONS OF THE FA ACROSS EAST CENTRAL INDIANA AND WEST CENTRAL OHIO. WITH THE FRONT LIFTING NORTH WENT ON THE WARMER SIDE OF GUIDANCE OR WARMER THAN GUIDANCE WITH LOW TEMPERATURES OVERNIGHT. WINDS WILL STAY UP SOME THROUGH THE OVERNIGHT HOURS WITH A FEW WIND GUSTS POSSIBLE AS WELL HOWEVER THE HIGHER WIND GUSTS WILL HOLD OFF UNTIL AFTER SUNRISE ACROSS THE FA. && .SHORT TERM /6 AM THIS MORNING THROUGH FRIDAY NIGHT/... FOUND MODEL AGREEMENT TO BE VERY STRONG THROUGH THIS PERIOD AND GOING FORECAST HAD LARGELY CAPTURED THE ENTIRE FCST SCENARIO EXTREMELY WELL...THUS CHANGES WERE REALLY FOCUSED ON DETAILS OF WINDS/TIMING OF STORMS...AND TIGHTENING UP GRADIENTS AHEAD/BEHIND THE EXPECTED COLD FRONT TOMORROW NIGHT. AFTERNOON GOES WATER VAPOR IMAGERY AND RAP ANALYSIS INDICATED A VERY DYNAMIC AND COLD LONGWAVE TROUGH /-30C AT 500MB NEAR SLC AT 12Z/ OVER THE INTERMOUNTAIN WEST WITH SEVERAL IMPRESSIVE CONVECTIVE COMPLEXES DOWNSTREAM NEAR THE ATTENDANT FRONTAL SYSTEMS OVER THE MID MS VALLEY. HEIGHTS HAVE BEEN RISING OVER THE OHIO VALLEY MUCH OF THE DAY BUT THAT PROCESS WILL TURN AROUND AS A STRONG SHORTWAVE TROUGH/UPPER JET DIGS THROUGH THE LONGWAVE TROUGH AND EJECTS INTO THE CENTRAL PLAINS...LOWERING HEIGHTS DOWNSTREAM OVER THE OHIO VALLEY AND ALLOWING A STRONG COLD FRONT AND LOW PRESSURE TO FURTHER ORGANIZE AND PUSH EAST TOWARD THE AREA. POOL OF VERY WARM /+15C AT H85/ AIR JUST TO OUR SOUTHWEST WILL LIFT NORTHWARD AS WARM MENTIONED ABOVE CONTINUES NORTH AND DEEPER SLY FLOW IS ATTAINED. AS DYNAMICS REALLY BEGIN TO INCREASE ON THURSDAY MORNING...LOW LEVEL WIND FIELD AND FALLING PRESSURES TO THE WEST WILL INDUCE A POTENT WARM ADVECTION REGIME...WITH EFFICIENT MIXING UNDER PARTLY CLOUDY SKIES. NAM/GFS SFC PRESSURE GRADIENT MAGNITUDES AND SOUNDING ANALYSIS VALID THURS AFTN SUGGESTS A WINDY DAY...SUSTAINED 20 TO 30 MPH WITH GUSTS TO 40 MPH...ESPECIALLY WEST OF I-71 FROM 10 AM THROUGH THE AFTN. A LITTLE CONCERNED FOR WIND ADVISORY CONDITIONS IN OUR FAR NORTHWEST WHICH IS A WIND PRONE AREA AND WILL BE UNDER THE STRONGEST INFLUENCE OF THE DEVELOPING/DEEPENING SFC-850MB CYCLONE AND ATTENDANT LOW LEVEL JET. WILL CONTINUE TO HIGHLIGHT WIND THREAT ON HWO. MAX TEMPS SHOULD WARM CONSIDERABLY...INTO THE 80S MOST AREAS AND WITH A MORE SELY TRAJECTORY OVER OUR EAST...THIS IS DOWNSLOPE/DRYING OFF THE APPALACHIAN RISE AND MAY ALLOW BETTER DEW POINT REDUCTION/WARMING. LIKELY WILL FALL A FEW DEGREES SHORT OF RECORDS...WHICH ARE IN THE MID/UPPER 80S. GETS VERY INTERESTING THURSDAY AFTER ABOUT 5 PM WHEN STRONG DEEP LAYERED ASCENT AND LOW LEVEL CONVERGENCE IN VICINITY OF FRONTAL ZONE TO THE WEST SHOULD CONTINUE TO FOSTER DEVELOPMENT OF A VERY LONG/STRONG SQUALL LINE. THERE/S BEEN HINTS IN THE HIGHER RES CONVECTION ALLOWING DATA THAT A FEW DISCRETE CELLS MAY FORM IN THE WARM SECTOR OVER OUR FAR WEST LATE AFTN/EARLY EVENING AND THAT WOULD BE PROBLEMATIC GIVEN A WEAK MLCINH FIELD /ERODED CAP/ AND MLCAPE AROUND 1500 J/KG AMIDST VERY STRONG FLOW /SHEAR/. RIGHT NOW AM NOT SEEING A STRONG/CONSISTENT SIGNAL THERE...SO KEEPING RAIN CHANCES LOW THROUGH THE DAY. AS THE EVENING WEARS ON...ADVANCING FRONTAL ZONE /OR PREFRONTAL TROUGH/ WILL BECOME FOCUS FOR CONTINUED ADVANCEMENT AND DEVELOPMENT OF CONVECTIVE SQUALL LINE INTO THE WFO ILN AREA SOMETIME BETWEEN 10 PM AND 2 AM. THINK LATEST SWODY2 FROM SPC IS REALISTIC...THAT WFO ILN WRN CWA WILL BE A TRANSITION AREA FROM A VERY POTENT QLCS WITH SEVERE THREAT...TO A NON-LIGHTNING PRODUCING LINE OF RAIN OR SHOWERS LATE IN THE NIGHT INTO THE EARLY MORNING HOURS ON FRIDAY. CLEARLY THE HIGHEST THREATS LOCALLY OF WIND ARE IN OUR FAR WEST BEFORE CONVECTION ENTRAINS AN INCREASINGLY HOSTILE LOW LEVEL AIRMASS /REF ABOVE COMMENT ABOUT DRYING ON SOUTH-SELY FLOW INTO ERN AREAS/...AND SOUNDING ANALYSIS FROM A MULTITUDE OF NWP SOURCES INDICATES ANY SURFACE BASED/NEAR SURFACE BASED INSTBY WILL BE MINIMAL AT BEST /100 J/KG/ WEST OF I-75. PRIOR NOCTURNAL QLCS EVENTS HOWEVER SUGGEST MLCAPE/MUCAPE IN THESE STRONGLY FORCED EVENTS IS OVERRATED TO A DEGREE...AND GIVEN THE EXPECTED 0-1KM SHEAR TOWARD 50KTS...THE SHAPE/ORIENTATION OF THE LOWEST 1KM TEMP TRACE IS VERY IMPORTANT FOR QLCS COUPLETS AND/OR DAMAGING WIND TRANSPORT TO THE SURFACE. FCST SOUNDINGS ARE HARD TO BUY INTO GIVEN FICKLE NATURE OF BOUNDARY LAYER RESOLUTION IN NWP...BUT ISOTHERMAL TO WEAKLY NEGATIVE LAPSE RATES INDEED SUGGESTS WE MAY VERY WELL HAVE A THREAT FOR DAMAGING GUSTS ESP IN THE FIRST COUPLE OF HOURS OF THE EVENT WEST OF I-75. WITH TIME...BUOYANCY REALLY TANKS AND EXPECT THIS CONVECTIVE SYSTEM TO STRUGGLE TO OR NOT PRODUCE LIGHTNING OVER THE ERN 1/2 OF THE FORECAST AREA LATE IN THE NIGHT AND FRIDAY MORNING. ALSO...WHILE WINDS MAY DECREASE EARLY IN THE EVENING...ISALLOBARIC COMPONENT IMMEDIATELY IN ADVANCE OF THE VERY SHARP/STRONG FRONAL ZONE WILL PROBABLY ALLOW FOR A BRIEF/RAPID INCREASE IN SUSTAINED AND GUSTS IMMEDIATELY AHEAD OF THE SQUALL LINE. FOR FLOOD CONCERN...SYSTEM WILL BE PROGRESSIVE AND HAVE HIGH CONFIDENCE IN RAIN AMOUNTS REMAINING LESS THAN AN INCH IN MOST AREAS. HEAVIEST WEST...LIGHTEST EAST. FEEL ANY FLOODING ISSUES WOULD BE BRIEF/NUISANCE AND TIED TO AREAS OF VERY MOIST SOILS FROM MERCER INTO HARDIN/DELAWARE COUNTIES. FRIDAY TO BE POLAR OPPOSITE OF THURSDAY...A 30 DEGREE TEMP CHANGE /PERHAPS MORE IN THE WEST/ FROM DAYTIME MAX TO DAYTIME MAX...WITH MORE GUSTY WINDS AND A RAPID END TO THE RAIN WITH DRY SLOT. THINK WIND ADVISORY MAY BECOME LIKELY IN NORTH/WEST AT SOME POINT AS SFC CYCLONE REACHES LOWEST PRESSURES /SUB-990MB/ OVER LAKE SUPERIOR. A VERY CHILLY/MISERABLE DAY IN COMPARISON TO THURSDAY. ENOUGH WEAKENING IN THE MSLP GRADIENT FRIDAY NIGHT AND POTENTIAL CLEARING TO WARRANT INSERT OF PATCHY FROST...THOUGH FOLLOWING NIGHT LOOKS EVEN BETTER FOR FROST. && .LONG TERM /SATURDAY THROUGH WEDNESDAY/... A STRONG AREA OF HIGH PRESSURE WILL BUILD IN THE MID SECTION OF THE COUNTRY ON SATURDAY AND NOSE INTO THE GREAT LAKES AND OHIO VALLEY REGION BY EVENING. SOUTHEAST FLOW WILL THEN GRADUALLY TURN SOUTH AHEAD OF THE NEXT COLD FRONT EXPECTED TO MOVE THROUGH LATE IN THE FORECAST PERIOD. MODELS ARE IN A WIDE RANGE FOR TIMING FOR THE TUESDAY/WEDNESDAY SYSTEM. THE PREVIOUS FORECAST APPEARS TO HAVE THE BEST INITIAL CONDITIONS BUT SOME NEIGHBORING OFFICES APPEAR HIGHER THAN I AM WILLING TO GO WITH RAIN CHANCES OVERNIGHT TUESDAY. GIVEN THE LATEST EUROPEAN WHICH SPINS THE SYSTEM UP IN THE MIDWEST ON TUESDAY...IT HAS A MUCH SLOWER AND MORE DEVELOPED SYSTEM THAN THE GFS WHICH IS INDICATING AN OPEN WAVE YET STRONG COLD FRONTAL PASSAGE EARLY WEDNESDAY. WPC HAS THIS FRONT ON THE OTHER SIDE OF THE APPALACHIANS AT THIS TIME WHICH APPEARS INCONSISTENT WITH THE REST OF THE GUIDANCE I SEE. UNTIL THE RAIN HITS WITH THE NEXT SYSTEM DAYS 6/7...TEMPERATURES WILL BE ON THE INCREASE AND START FROM A COOLER 50S ON SATURDAY WITH OVERNIGHT LOWS LIKELY NEEDING FROST HEADLINES. BY THIS TIME NEXT WEEK AHEAD OF THE COLD FRONT...70S WILL BE FOUND AGAIN WITH OVERNIGHT LOWS IN THE 50S. HAVE GONE WARMER THAN GUIDANCE AHEAD OF THE NEXT SYSTEM BUT FEEL THAT THE FORECAST WILL CONTINUE TO BE ADJUSTED UPWARD A LITTLE BIT EACH DAY. && .AVIATION /06Z THURSDAY THROUGH MONDAY/... A WARM FRONT WILL CONTINUE TO MOVE NORTH TOWARD THE GREAT LAKES REGION THIS MORNING. POTENT UPPER LEVEL TROUGH WILL MOVE INTO THE PLAINS TODAY. AS IT DOES...SURFACE LOW PRESSURE WILL DEEPEN AS IT MOVE NE FROM THE SOUTHERN PLAINS TO THE UPPER MISSISSIPPI RIVER VALLEY. OUR AREA WILL BE MAINLY WARM SECTORED TODAY WITH A MIX OF DIURNAL CUMULUS AND HIGH LEVEL CLOUDS. THERE IS STILL A SMALL CHANCE OF A POP UP SHOWER OR STORM IN THE WARM SECTOR...BUT THIS IS NOT HIGH ENOUGH TO MENTION IN THE TAFS. AS THE SURFACE LOW DEEPENS AND DAYTIME MIXING KICKS IN...SOUTHERLY WINDS WILL INCREASE AND WILL BE GUSTY BETWEEN 30 AND 35 KNOTS. FOR TONIGHT...DEEPENING LOW PRESSURE WILL MOVE FROM THE UPPER MISSISSIPPI RIVER VALLEY TO THE U.P. OF MICHIGAN. A DYNAMIC COLD FRONT IS FORECAST TO PUSH EAST INTO THE REGION BETWEEN 06Z AND 12Z. AS IT DOES...A LINE OF SHOWERS AND EMBEDDED THUNDERSTORMS ARE EXPECTED ALONG THE COLD FRONT...FOLLOWED BY A PERIOD OF MODERATE TO LOCALLY HEAVY RAIN SHOWERS. THIS WILL RESULT IN CONDITIONS DROPPING INTO THE MVFR CATEGORY ALONG WITH SOME IFR VISIBILITIES IN THE HEAVIER RAIN. ALSO...WINDS WILL CONTINUE GUSTY AND SHIFT TO THE WEST WITH FROPA. WINDS WILL BE LOCALLY HIGHER IN AND NEAR THUNDERSTORMS. ATTM...IT APPEARS INSTABILITY WILL BE WEAKENING AS THE FRONT PUSHES TOWARD THE KCMH/KLCK TAF SITES TOWARD 12Z SO NOT MUCH THUNDER MAY BE LEFT BY THE TIME IT REACHES THESE TERMINALS. OUTLOOK...MVFR CONDITIONS WITH LOCAL IFR VISIBILITIES EXPECTED IN SHOWERS FRIDAY MORNING. WEST WINDS GUSTING TO 30 KT EXPECTED FRIDAY. && .ILN WATCHES/WARNINGS/ADVISORIES... OH...NONE. KY...NONE. IN...NONE. && $$ SYNOPSIS...BINAU NEAR TERM...NOVAK SHORT TERM...BINAU LONG TERM...FRANKS AVIATION...HICKMAN
AREA FORECAST DISCUSSION
NWS WILMINGTON OH
932 PM EDT WED APR 17 2013 .SYNOPSIS... A POTENT SPRING STORM SYSTEM WILL EJECT NORTHEAST THROUGH THE MID MISSISSIPPI VALLEY TONIGHT THROUGH FRIDAY...BRINGING A WILD SWING IN TEMPERATURE AND THE THREAT OF STRONG TO SEVERE THUNDERSTORMS. VERY WARM CONDITIONS ON THURSDAY WITH GUSTY SOUTH WINDS WILL BE FOLLOWED BY EVEN GUSTIER NORTHWEST WINDS AND TEMPERATURES SOME 30 DEGREES LOWER THAN THAN ON THURSDAY. IN THE WAKE OF THIS SYSTEM...COOL CANADIAN HIGH PRESSURE WILL SETTLE INTO THE OHIO VALLEY FOR THE WEEKEND WITH THE THREAT OF MORNING FROST AND SOME DRY WEATHER. && .NEAR TERM /UNTIL 6 AM THURSDAY MORNING/... WARM FRONTAL BOUNDARY WILL CONTINUE TO LIFT NORTH THROUGH THE OVERNIGHT HOURS. MOST LOCATIONS WILL REMAIN DRY THROUGH THE OVERNIGHT HOURS HOWEVER A FEW ISOLATED STORMS MAY REACH INTO NW PORTIONS OF THE FA ACROSS EAST CENTRAL INDIANA AND WEST CENTRAL OHIO. WITH THE FRONT LIFTING NORTH WENT ON THE WARMER SIDE OF GUIDANCE OR WARMER THAN GUIDANCE WITH LOW TEMPERATURES OVERNIGHT. WINDS WILL STAY UP SOME THROUGH THE OVERNIGHT HOURS WITH A FEW WIND GUSTS POSSIBLE AS WELL HOWEVER THE HIGHER WIND GUSTS WILL HOLD OFF UNTIL AFTER SUNRISE ACROSS THE FA. && .SHORT TERM /6 AM THURSDAY MORNING THROUGH FRIDAY NIGHT/... FOUND MODEL AGREEMENT TO BE VERY STRONG THROUGH THIS PERIOD AND GOING FORECAST HAD LARGELY CAPTURED THE ENTIRE FCST SCENARIO EXTREMELY WELL...THUS CHANGES WERE REALLY FOCUSED ON DETAILS OF WINDS/TIMING OF STORMS...AND TIGHTENING UP GRADIENTS AHEAD/BEHIND THE EXPECTED COLD FRONT TOMORROW NIGHT. AFTERNOON GOES WATER VAPOR IMAGERY AND RAP ANALYSIS INDICATED A VERY DYNAMIC AND COLD LONGWAVE TROUGH /-30C AT 500MB NEAR SLC AT 12Z/ OVER THE INTERMOUNTAIN WEST WITH SEVERAL IMPRESSIVE CONVECTIVE COMPLEXES DOWNSTREAM NEAR THE ATTENDANT FRONTAL SYSTEMS OVER THE MID MS VALLEY. HEIGHTS HAVE BEEN RISING OVER THE OHIO VALLEY MUCH OF THE DAY BUT THAT PROCESS WILL TURN AROUND AS A STRONG SHORTWAVE TROUGH/UPPER JET DIGS THROUGH THE LONGWAVE TROUGH AND EJECTS INTO THE CENTRAL PLAINS...LOWERING HEIGHTS DOWNSTREAM OVER THE OHIO VALLEY AND ALLOWING A STRONG COLD FRONT AND LOW PRESSURE TO FURTHER ORGANIZE AND PUSH EAST TOWARD THE AREA. POOL OF VERY WARM /+15C AT H85/ AIR JUST TO OUR SOUTHWEST WILL LIFT NORTHWARD AS WARM MENTIONED ABOVE CONTINUES NORTH AND DEEPER SLY FLOW IS ATTAINED. AS DYNAMICS REALLY BEGIN TO INCREASE ON THURSDAY MORNING...LOW LEVEL WIND FIELD AND FALLING PRESSURES TO THE WEST WILL INDUCE A POTENT WARM ADVECTION REGIME...WITH EFFICIENT MIXING UNDER PARTLY CLOUDY SKIES. NAM/GFS SFC PRESSURE GRADIENT MAGNITUDES AND SOUNDING ANALYSIS VALID THURS AFTN SUGGESTS A WINDY DAY...SUSTAINED 20 TO 30 MPH WITH GUSTS TO 40 MPH...ESPECIALLY WEST OF I-71 FROM 10 AM THROUGH THE AFTN. A LITTLE CONCERNED FOR WIND ADVISORY CONDITIONS IN OUR FAR NORTHWEST WHICH IS A WIND PRONE AREA AND WILL BE UNDER THE STRONGEST INFLUENCE OF THE DEVELOPING/DEEPENING SFC-850MB CYCLONE AND ATTENDANT LOW LEVEL JET. WILL CONTINUE TO HIGHLIGHT WIND THREAT ON HWO. MAX TEMPS SHOULD WARM CONSIDERABLY...INTO THE 80S MOST AREAS AND WITH A MORE SELY TRAJECTORY OVER OUR EAST...THIS IS DOWNSLOPE/DRYING OFF THE APPALACHIAN RISE AND MAY ALLOW BETTER DEW POINT REDUCTION/WARMING. LIKELY WILL FALL A FEW DEGREES SHORT OF RECORDS...WHICH ARE IN THE MID/UPPER 80S. GETS VERY INTERESTING THURSDAY AFTER ABOUT 5 PM WHEN STRONG DEEP LAYERED ASCENT AND LOW LEVEL CONVERGENCE IN VICINITY OF FRONTAL ZONE TO THE WEST SHOULD CONTINUE TO FOSTER DEVELOPMENT OF A VERY LONG/STRONG SQUALL LINE. THERE/S BEEN HINTS IN THE HIGHER RES CONVECTION ALLOWING DATA THAT A FEW DISCRETE CELLS MAY FORM IN THE WARM SECTOR OVER OUR FAR WEST LATE AFTN/EARLY EVENING AND THAT WOULD BE PROBLEMATIC GIVEN A WEAK MLCINH FIELD /ERODED CAP/ AND MLCAPE AROUND 1500 J/KG AMIDST VERY STRONG FLOW /SHEAR/. RIGHT NOW AM NOT SEEING A STRONG/CONSISTENT SIGNAL THERE...SO KEEPING RAIN CHANCES LOW THROUGH THE DAY. AS THE EVENING WEARS ON...ADVANCING FRONTAL ZONE /OR PREFRONTAL TROUGH/ WILL BECOME FOCUS FOR CONTINUED ADVANCEMENT AND DEVELOPMENT OF CONVECTIVE SQUALL LINE INTO THE WFO ILN AREA SOMETIME BETWEEN 10 PM AND 2 AM. THINK LATEST SWODY2 FROM SPC IS REALISTIC...THAT WFO ILN WRN CWA WILL BE A TRANSITION AREA FROM A VERY POTENT QLCS WITH SEVERE THREAT...TO A NON-LIGHTNING PRODUCING LINE OF RAIN OR SHOWERS LATE IN THE NIGHT INTO THE EARLY MORNING HOURS ON FRIDAY. CLEARLY THE HIGHEST THREATS LOCALLY OF WIND ARE IN OUR FAR WEST BEFORE CONVECTION ENTRAINS AN INCREASINGLY HOSTILE LOW LEVEL AIRMASS /REF ABOVE COMMENT ABOUT DRYING ON SOUTH-SELY FLOW INTO ERN AREAS/...AND SOUNDING ANALYSIS FROM A MULTITUDE OF NWP SOURCES INDICATES ANY SURFACE BASED/NEAR SURFACE BASED INSTBY WILL BE MINIMAL AT BEST /100 J/KG/ WEST OF I-75. PRIOR NOCTURNAL QLCS EVENTS HOWEVER SUGGEST MLCAPE/MUCAPE IN THESE STRONGLY FORCED EVENTS IS OVERRATED TO A DEGREE...AND GIVEN THE EXPECTED 0-1KM SHEAR TOWARD 50KTS...THE SHAPE/ORIENTATION OF THE LOWEST 1KM TEMP TRACE IS VERY IMPORTANT FOR QLCS COUPLETS AND/OR DAMAGING WIND TRANSPORT TO THE SURFACE. FCST SOUNDINGS ARE HARD TO BUY INTO GIVEN FICKLE NATURE OF BOUNDARY LAYER RESOLUTION IN NWP...BUT ISOTHERMAL TO WEAKLY NEGATIVE LAPSE RATES INDEED SUGGESTS WE MAY VERY WELL HAVE A THREAT FOR DAMAGING GUSTS ESP IN THE FIRST COUPLE OF HOURS OF THE EVENT WEST OF I-75. WITH TIME...BUOYANCY REALLY TANKS AND EXPECT THIS CONVECTIVE SYSTEM TO STRUGGLE TO OR NOT PRODUCE LIGHTNING OVER THE ERN 1/2 OF THE FORECAST AREA LATE IN THE NIGHT AND FRIDAY MORNING. ALSO...WHILE WINDS MAY DECREASE EARLY IN THE EVENING...ISALLOBARIC COMPONENT IMMEDIATELY IN ADVANCE OF THE VERY SHARP/STRONG FRONAL ZONE WILL PROBABLY ALLOW FOR A BRIEF/RAPID INCREASE IN SUSTAINED AND GUSTS IMMEDIATELY AHEAD OF THE SQUALL LINE. FOR FLOOD CONCERN...SYSTEM WILL BE PROGRESSIVE AND HAVE HIGH CONFIDENCE IN RAIN AMOUNTS REMAINING LESS THAN AN INCH IN MOST AREAS. HEAVIEST WEST...LIGHTEST EAST. FEEL ANY FLOODING ISSUES WOULD BE BRIEF/NUISANCE AND TIED TO AREAS OF VERY MOIST SOILS FROM MERCER INTO HARDIN/DELAWARE COUNTIES. FRIDAY TO BE POLAR OPPOSITE OF THURSDAY...A 30 DEGREE TEMP CHANGE /PERHAPS MORE IN THE WEST/ FROM DAYTIME MAX TO DAYTIME MAX...WITH MORE GUSTY WINDS AND A RAPID END TO THE RAIN WITH DRY SLOT. THINK WIND ADVISORY MAY BECOME LIKELY IN NORTH/WEST AT SOME POINT AS SFC CYCLONE REACHES LOWEST PRESSURES /SUB-990MB/ OVER LAKE SUPERIOR. A VERY CHILLY/MISERABLE DAY IN COMPARISON TO THURSDAY. ENOUGH WEAKENING IN THE MSLP GRADIENT FRIDAY NIGHT AND POTENTIAL CLEARING TO WARRANT INSERT OF PATCHY FROST...THOUGH FOLLOWING NIGHT LOOKS EVEN BETTER FOR FROST. && .LONG TERM /SATURDAY THROUGH WEDNESDAY/... A STRONG AREA OF HIGH PRESSURE WILL BUILD IN THE MID SECTION OF THE COUNTRY ON SATURDAY AND NOSE INTO THE GREAT LAKES AND OHIO VALLEY REGION BY EVENING. SOUTHEAST FLOW WILL THEN GRADUALLY TURN SOUTH AHEAD OF THE NEXT COLD FRONT EXPECTED TO MOVE THROUGH LATE IN THE FORECAST PERIOD. MODELS ARE IN A WIDE RANGE FOR TIMING FOR THE TUESDAY/WEDNESDAY SYSTEM. THE PREVIOUS FORECAST APPEARS TO HAVE THE BEST INITIAL CONDITIONS BUT SOME NEIGHBORING OFFICES APPEAR HIGHER THAN I AM WILLING TO GO WITH RAIN CHANCES OVERNIGHT TUESDAY. GIVEN THE LATEST EUROPEAN WHICH SPINS THE SYSTEM UP IN THE MIDWEST ON TUESDAY...IT HAS A MUCH SLOWER AND MORE DEVELOPED SYSTEM THAN THE GFS WHICH IS INDICATING AN OPEN WAVE YET STRONG COLD FRONTAL PASSAGE EARLY WEDNESDAY. WPC HAS THIS FRONT ON THE OTHER SIDE OF THE APPALACHIANS AT THIS TIME WHICH APPEARS INCONSISTENT WITH THE REST OF THE GUIDANCE I SEE. UNTIL THE RAIN HITS WITH THE NEXT SYSTEM DAYS 6/7...TEMPERATURES WILL BE ON THE INCREASE AND START FROM A COOLER 50S ON SATURDAY WITH OVERNIGHT LOWS LIKELY NEEDING FROST HEADLINES. BY THIS TIME NEXT WEEK AHEAD OF THE COLD FRONT...70S WILL BE FOUND AGAIN WITH OVERNIGHT LOWS IN THE 50S. HAVE GONE WARMER THAN GUIDANCE AHEAD OF THE NEXT SYSTEM BUT FEEL THAT THE FORECAST WILL CONTINUE TO BE ADJUSTED UPWARD A LITTLE BIT EACH DAY. && .AVIATION /01Z THURSDAY THROUGH MONDAY/... A WARM FRONT SITUATED ACROSS THE TAF SITES WILL CONTINUE TO PUSH NORTH TONIGHT. WINDS WILL GRADUALLY BECOME MORE SOUTHERLY ACROSS THE TAF SITES. GUIDANCE IS SUGGESTING SOME MVFR FOG AT THE TAF SITES OVERNIGHT HOWEVER BELIEVE WITH WINDS STAYING UP THROUGH THE NIGHT THAT FOG WILL PROBABLY NOT BE AN ISSUE. WINDS WILL REALLY RAMP UP FOR THE DAY ON THURSDAY WITH WIND GUSTS EXCEEDING 30 KNOTS AT TIMES FOR THE LATE MORNING AND THROUGH THE AFTERNOON HOURS. ALTHOUGH A FEW SPOTTY SHOWERS AND THUNDERSTORMS WILL BE POSSIBLE DURING THE DAY ON THURSDAY COVERAGE WILL BE VERY LIMITED AND THEREFORE LEFT OUT OF THE TAFS AT THIS TIME. OUTLOOK...GUSTY SOUTHERLY WINDS WILL CONTINUE THROUGH THURSDAY EVENING. A BRIEF PERIOD OF MVFR CEILINGS AND VISIBILITIES ARE POSSIBLE AS SHOWERS AND THUNDERSTORMS MOVE THROUGH LATE THURSDAY NIGHT AND EARLY FRIDAY MORNING. WEST WINDS GUSTING TO 30 KT LIKELY FRIDAY. && .ILN WATCHES/WARNINGS/ADVISORIES... OH...NONE. KY...NONE. IN...NONE. && $$ SYNOPSIS...BINAU NEAR TERM...NOVAK SHORT TERM...BINAU LONG TERM...FRANKS AVIATION...NOVAK
AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NWS RAPID CITY SD
1047 PM MDT WED APR 17 2013 .UPDATE... ISSUED AT 951 PM MDT WED APR 17 2013 KUDX RADAR INDICATES PERSISTENT BAND OF -SN FROM KEFC TO KIEN...IN AN AREA OF CYCLONIC FLOW AND STEEP LOW LEVEL LAPSE RATES. GIVEN 00Z KUNR SOUNDING...EXPECT ACTIVITY TO PERSIST LONGER INTO THE NIGHT...SO WILL EXPAND PREVIOUSLY HIGHER POPS AND EXTEND THEM IN TIME. SNOW CONTINUES TO EXPAND IN NE HEADING FOR SOUTH CENTRAL SD...SO FORECAST THERE STILL LOOK REASONABLE. UPDATE ISSUED AT 502 PM MDT WED APR 17 2013 LATEST WATER VAPOUR LOOP AND 21Z RAP GUIDANCE SHOW NEXT WAVE OVER NM...HEADING SWIFTLY TO THE NORTHEAST ON NOSE OF 130KT JET. LIFT ON NOSE OF THIS JET STREAK AND EXITING JET STREAK OVER THE UPPER MIDWEST WILL COMBINE TO BRING INCREASING AREAS OF -SN OVER NE PER KLNX RADAR...WHICH WILL HEAD INTO SOUTH CENTRAL SD TONIGHT. EXPECT MAIN ACCUMULATING SNOWS TO BE OVER THESE AREAS OVERNIGHT. FURTHER WEST -SN WILL LINGER...BUT ACCUMULATIONS WILL BE LIGHT. WILL THUS SHAVE OFF ALL HEADLINES SAVE FOR SOUTH CENTRAL SD WHERE SEVERAL MORE INCHES OF SNOW ARE EXPECTED OVERNIGHT. && .SHORT TERM...THIS EVENING THROUGH THURSDAY NIGHT ISSUED AT 238 PM MDT WED APR 17 2013 CURRENT SURFACE ANALYSIS PLACES LOW OVER NORTHERN NEW MEXICO WITH HIGH SETTLING INTO THE NORTHERN ROCKIES. UPPER LEVEL ANALYSIS PLACES DEEP TROF OVER THE WRN INTO THE CTRL CONUS WITH AXIS STRETCHING FROM ERN SASKATCHEWAN SOUTHWARD TOWARDS THE FOUR CORNERS REGION...WITH BASE CLOSING OFF NEAR WRN COLORADO. VARIETY OF WAVES CONTINUE TO PUSH UP ALONG THE FRONT OF THE WAVE. MAIN AREA OF SNOW OVER PTNS OF SW INTO S CTRL SD ORIENTATED ALONG AXIS OF INCREASING 700 MB FRONTOGENESIS...WHILE OTHER SMALLER BANDS CONTINUE OVER THE CWA. FOR TONIGHT...UPPER TROF CONTINUES ITS SLOW PUSH TO THE EAST WITH SNOW SLOWLY TAPERING FROM WEST TO EAST THROUGH THE OVERNIGHT OVER NERN WYO INTO WRN SD. OVER S CTRL SD...PRIMARY BAND OF SNOW SHIFTS OVER THE AREA THIS EVENING. LATE TONIGHT PRIMARY WAVE WRAPPING AROUND CLOSED LOW EJECTING INTO THE PLAINS WILL PASS MAINLY TO THE EAST...THOUGH ENOUGH LIFT WITH THIS SHOULD KEEP SNOWFALL GOING INTO THE MORNING HOURS. ON THURSDAY...SOME SNOW WILL LINGER INTO THE MORNING HOURS OVER S CTRL SD BEFORE SLOWLY ENDING INTO THE AFTERNOON AS UPPER LOW SLOWLY WORKS ITS WAY TO THE EAST. OVER REMAINDER OF THE CWA...DRY CONDITIONS ARE EXPECTED AS RIDGING QUICKLY BUILDS IN. SFC LOW EJECTS THRU THE MIDWEST AND DEEPENS BRINGING INCREASING NRNLY WINDS TO THE ERN CWA...WHICH MAY LEAD TO SOME BLOWING SNOW. && .LONG TERM...FRIDAY THROUGH WEDNESDAY ISSUED AT 238 PM MDT WED APR 17 2013 MOSTLY DRY CONDITIONS ARE EXPECTED FRIDAY AS A SHORT WAVE RIDGE CROSSES THE NORTHERN PLAINS. AN UPPER TROF WILL SET UP ACROSS THE NORTHERN PLAINS FOR THE WEEKEND INTO EARLY NEXT WEEK. THIS WILL BRING PERIODIC CHANCES FOR RAIN/SNOW ALONG WITH TEMPERATURES REMAINING BELOW AVERAGE. AN UPPER LEVEL RIDGE WILL START TO MOVE INTO THE NORTHERN PLAINS AROUND MIDWEEK...BRINGING DRY CONDITIONS AND MORE SEASONABLE TEMPERATURES. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT) ISSUED AT 1045 PM MDT WED APR 17 2013 WIDESPREAD IFR CONDITIONS OVER SD WILL SLOWLY MOVE EAST TONIGHT...LEADING TO IMPROVING CONDITIONS FROM WEST TO EAST ON THURSDAY AS A STORM SYSTEM EXITS THE REGION. LEFTOVER MVFR CIGS/LOCAL IFR CIGS OVER NORTHEAST WY WILL SHIFT EAST TONIGHT LEADING TO MAINLY VFR CONDITIONS THURSDAY. && .UNR WATCHES/WARNINGS/ADVISORIES... SD...WINTER WEATHER ADVISORY UNTIL 6 AM MDT THURSDAY FOR SDZ043-044. WINTER WEATHER ADVISORY UNTIL NOON CDT THURSDAY FOR SDZ046-047- 049. WY...NONE. && $$ UPDATE...HELGESON SHORT TERM...77 LONG TERM...15 AVIATION...HELGESON
AREA FORECAST DISCUSSION FOR WESTERN SD AND NORTHEASTERN WY
NWS RAPID CITY SD
955 PM MDT WED APR 17 2013 .UPDATE... ISSUED AT 951 PM MDT WED APR 17 2013 KUDX RADAR INDICATES PERSISTENT BAND OF -SN FROM KEFC TO KIEN...IN AN AREA OF CYCLONIC FLOW AND STEEP LOW LEVEL LAPSE RATES. GIVEN 00Z KUNR SOUNDING...EXPECT ACTIVITY TO PERSIST LONGER INTO THE NIGHT...SO WILL EXPAND PREVIOUSLY HIGHER POPS AND EXTEND THEM IN TIME. SNOW CONTINUES TO EXPAND IN NE HEADING FOR SOUTH CENTRAL SD...SO FORECAST THERE STILL LOOK REASONABLE. UPDATE ISSUED AT 502 PM MDT WED APR 17 2013 LATEST WATER VAPOUR LOOP AND 21Z RAP GUIDANCE SHOW NEXT WAVE OVER NM...HEADING SWIFTLY TO THE NORTHEAST ON NOSE OF 130KT JET. LIFT ON NOSE OF THIS JET STREAK AND EXITING JET STREAK OVER THE UPPER MIDWEST WILL COMBINE TO BRING INCREASING AREAS OF -SN OVER NE PER KLNX RADAR...WHICH WILL HEAD INTO SOUTH CENTRAL SD TONIGHT. EXPECT MAIN ACCUMULATING SNOWS TO BE OVER THESE AREAS OVERNIGHT. FURTHER WEST -SN WILL LINGER...BUT ACCUMULATIONS WILL BE LIGHT. WILL THUS SHAVE OFF ALL HEADLINES SAVE FOR SOUTH CENTRAL SD WHERE SEVERAL MORE INCHES OF SNOW ARE EXPECTED OVERNIGHT. && .SHORT TERM...THIS EVENING THROUGH THURSDAY NIGHT ISSUED AT 238 PM MDT WED APR 17 2013 CURRENT SURFACE ANALYSIS PLACES LOW OVER NORTHERN NEW MEXICO WITH HIGH SETTLING INTO THE NORTHERN ROCKIES. UPPER LEVEL ANALYSIS PLACES DEEP TROF OVER THE WRN INTO THE CTRL CONUS WITH AXIS STRETCHING FROM ERN SASKATCHEWAN SOUTHWARD TOWARDS THE FOUR CORNERS REGION...WITH BASE CLOSING OFF NEAR WRN COLORADO. VARIETY OF WAVES CONTINUE TO PUSH UP ALONG THE FRONT OF THE WAVE. MAIN AREA OF SNOW OVER PTNS OF SW INTO S CTRL SD ORIENTATED ALONG AXIS OF INCREASING 700 MB FRONTOGENESIS...WHILE OTHER SMALLER BANDS CONTINUE OVER THE CWA. FOR TONIGHT...UPPER TROF CONTINUES ITS SLOW PUSH TO THE EAST WITH SNOW SLOWLY TAPERING FROM WEST TO EAST THROUGH THE OVERNIGHT OVER NERN WYO INTO WRN SD. OVER S CTRL SD...PRIMARY BAND OF SNOW SHIFTS OVER THE AREA THIS EVENING. LATE TONIGHT PRIMARY WAVE WRAPPING AROUND CLOSED LOW EJECTING INTO THE PLAINS WILL PASS MAINLY TO THE EAST...THOUGH ENOUGH LIFT WITH THIS SHOULD KEEP SNOWFALL GOING INTO THE MORNING HOURS. ON THURSDAY...SOME SNOW WILL LINGER INTO THE MORNING HOURS OVER S CTRL SD BEFORE SLOWLY ENDING INTO THE AFTERNOON AS UPPER LOW SLOWLY WORKS ITS WAY TO THE EAST. OVER REMAINDER OF THE CWA...DRY CONDITIONS ARE EXPECTED AS RIDGING QUICKLY BUILDS IN. SFC LOW EJECTS THRU THE MIDWEST AND DEEPENS BRINGING INCREASING NRNLY WINDS TO THE ERN CWA...WHICH MAY LEAD TO SOME BLOWING SNOW. && .LONG TERM...FRIDAY THROUGH WEDNESDAY ISSUED AT 238 PM MDT WED APR 17 2013 MOSTLY DRY CONDITIONS ARE EXPECTED FRIDAY AS A SHORT WAVE RIDGE CROSSES THE NORTHERN PLAINS. AN UPPER TROF WILL SET UP ACROSS THE NORTHERN PLAINS FOR THE WEEKEND INTO EARLY NEXT WEEK. THIS WILL BRING PERIODIC CHANCES FOR RAIN/SNOW ALONG WITH TEMPERATURES REMAINING BELOW AVERAGE. AN UPPER LEVEL RIDGE WILL START TO MOVE INTO THE NORTHERN PLAINS AROUND MIDWEEK...BRINGING DRY CONDITIONS AND MORE SEASONABLE TEMPERATURES. && .AVIATION...(FOR THE 00Z TAFS THROUGH 00Z THURSDAY EVENING) ISSUED AT 502 PM MDT WED APR 17 2013 WIDESPREAD IFR/MVFR CONDITIONS DUE TO LOW CLOUDS/-SN EXPECTED TONIGHT INTO EARLY THURSDAY MORNING ACROSS MUCH WESTERN SD. CONDITIONS WILL BEGIN TO SLOWLY IMPROVE ACROSS NORTHEAST WYOMING LATER THIS EVENING AND OVERNIGHT AS SNOW TAPERS OFF AND CEILINGS RISE TO MVFR LEVELS. CONDITIONS WILL THEN IMPROVE THURSDAY AS STORM SYSTEM MOVES TO THE EAST. && .UNR WATCHES/WARNINGS/ADVISORIES... SD...WINTER WEATHER ADVISORY UNTIL 6 AM MDT THURSDAY FOR SDZ043-044. WINTER WEATHER ADVISORY UNTIL NOON CDT THURSDAY FOR SDZ046-047- 049. WY...NONE. && $$ UPDATE...HELGESON SHORT TERM...77 LONG TERM...15 AVIATION...HELGESON
AREA FORECAST DISCUSSION
NWS NASHVILLE TN
400 AM CDT THU APR 18 2013 ...MODERATE RISK OF SEVERE THUNDERSTORMS THIS EVENING INTO TONIGHT... .DISCUSSION... FEW OVERALL CHANGES TO THE FORECAST OVER THE NEXT WEEK...WITH MAINLY SLIGHT ADJUSTMENTS TO TEMPS AND TIMING OF PRECIP. A LARGE H5 TROUGH OVER THE PLAINS STATES WILL SHIFT INTO THE MISSISSIPPI VALLEY TODAY THEN ACROSS THE TENNESSEE VALLEY TONIGHT...WITH AN ASSOCIATED STRONG COLD FRONT SWEEPING THROUGH THE MID STATE TONIGHT. BEFORE THE FRONT ARRIVES...ANOTHER SUMMER-LIKE DAY IS ON TAP WITH TEMPERATURES STARTING OUT IN THE 60S TO AROUND 70 THIS MORNING THEN WARMING UP INTO THE LOW TO MID 80S AREAWIDE THIS AFTERNOON. AS A SUB-1000MB SURFACE LOW TAKES SHAPE ACROSS THE MIDWEST...925MB WINDS WILL INCREASE ACROSS OUR REGION INTO THE 40-50KT RANGE TODAY LEADING TO GUSTY SOUTH WINDS AT THE SURFACE. ANTICIPATING SOUTH WINDS IN THE 15 TO 30 MPH RANGE DEVELOPING LATER THIS MORNING...THEN CONTINUING INTO THE AFTERNOON HOURS BEFORE SUBSIDING SOMEWHAT EARLY IN THE EVENING. OCCASIONAL GUSTS TO NEAR 40 MPH APPEAR LIKELY AS WELL BASED ON BUFKIT SOUNDINGS. SOUTH WINDS WILL INCREASE AGAIN LATER IN THE EVENING AS A SHARP PRESSURE GRADIENT MOVES ACROSS THE MID STATE AHEAD OF THE COLD FRONT. TO SIMPLIFY MATTERS...HAVE ISSUED A WIND ADVISORY FOR ALL ZONES BEGINNING LATER THIS MORNING AND CONTINUING THROUGH THE EARLY MORNING HOURS ON FRIDAY. SPC HAS PLACED AREAS ALONG AND WEST OF THE I-65 CORRIDOR IN A MODERATE RISK FOR SEVERE STORMS THURSDAY EVENING WITH A SLIGHT RISK TO THE EAST THURSDAY NIGHT. 00Z GFS/NAM/ECMWF AND LATEST HIGH RESOLUTION 4.0 KM WRF...NSSL WRF...AND HRRR ALL INDICATE A STRONG TO SEVERE QLCS WILL FORM LATER TODAY ALONG THE FRONT...REACHING THE TENNESSEE RIVER BY MID EVENING...I-65 CORRIDOR AROUND MIDNIGHT...AND EXIT EAST OF THE CWA NEAR/AFTER SUNRISE FRIDAY MORNING. MODELS CONTINUE TO DEPICT GENERALLY WEAK INSTABILITY AROUND 500 J/KG AHEAD OF THE LINE...BUT SOME GUIDANCE INDICATES A SURGE OF MID/UPPER 60S DEWPOINTS COMING NORTHWARD AHEAD OF THE QLCS WHICH COULD BUMP UP CAPE VALUES TO NEAR/OVER 1000 J/KG ACROSS WESTERN ZONES. REGARDLESS...IMPRESSIVE 0-3KM SRH STRENGTHENING INTO THE 500-800 M2/S2 RANGE AND VERY LONG CURVED HODOGRAPHS SUGGESTS A SIGNIFICANT DAMAGING WIND THREAT WITH THE LINE OF STORMS ALONG WITH SOME QLCS TORNADOES. HIGHEST RISK OF DAMAGING WINDS/TORNADOES IS EXPECTED TO BE ALONG/WEST OF I-65 IN THE 02-06Z TIMEFRAME ACROSS THE MODERATE RISK AREA...AS STORMS WILL ENCOUNTER INCREASINGLY LESS INSTABILITY AND WEAKENING SHEAR OFF TO THE EAST. STRATIFORM RAIN AND A FEW THUNDERSTORMS WILL CONTINUE MUCH OF THE NIGHT BEHIND THE QLCS WITH RAINFALL COMING TO AN END FROM WEST TO EAST FRIDAY MORNING. MUCH COOLER TEMPERATURES ARE ANTICIPATED FRIDAY AND SATURDAY WITH LOWS FALLING INTO THE MID TO UPPER 30S SATURDAY MORNING. WITH SURFACE RIDGE SETTLING OVER THE MID STATE...LIGHT TO CALM WINDS...AND DEWPOINTS FALLING INTO THE 20S AND 30S...PATCHY FROST APPEARS POSSIBLE FOR MUCH OF THE FORECAST AREA AND HAVE ADDED MENTION TO ZONES. AREA WILL BEGIN TO WARMUP FROM SUNDAY INTO EARLY NEXT WEEK AS SOUTHERLY FLOW BEGINS ANEW. FEW CHANGES WERE MADE IN THE EXTENDED FORECAST WITH NEXT CHANCE FOR RAIN AROUND TUESDAY/WEDNESDAY OF NEXT WEEK. && .PRELIMINARY POINT TEMPS/POPS... NASHVILLE 85 53 58 37 / 10 100 20 10 CLARKSVILLE 85 49 57 34 / 10 100 10 10 CROSSVILLE 80 58 61 34 / 10 100 60 10 COLUMBIA 85 54 60 37 / 10 100 20 10 LAWRENCEBURG 85 54 60 36 / 10 100 20 10 WAVERLY 84 50 57 35 / 10 100 10 10 && .OHX WATCHES/WARNINGS/ADVISORIES... WIND ADVISORY FROM 10 AM THIS MORNING TO 1 AM CDT FRIDAY FOR TNZ005>011-022>034-056>066-075-077>080-093>095. && $$ SHAMBURGER
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
1143 PM CDT WED APR 17 2013 .UPDATE... ISSUED AT 904 PM CDT WED APR 17 2013 THE NEXT BAND OF RAIN IS CURRENTLY MOVING THROUGH THE REGION AND SHOULD LAST THROUGH THE NEXT 2 TO 4 HOURS PROVIDING ABOUT 0.20 TO 0.40 OF AN INCH OF RAIN. WITH THE MAIN AXIS OF LOW LEVEL MOISTURE TRANSPORT AND HIGHER INSTABILITY STAYING TO THE SOUTHEAST INTO TOMORROW...HAVE DECIDED TO DROP THE FLOOD WATCH FOR THE NORTHWESTERN HALF OF THE FORECAST AREA. WILL HAVE AN UPDATE COMING OUT SHORTLY WITH THIS CANCELLATION. OTHERWISE...LIGHTNING HAS REALLY DWINDLED OVER THE PAST FEW HOURS AS THIS RAIN HAS RUN INTO THE REGION THAT HAS LITTLE TO NO INSTABILITY. THE LAST FEW RUNS OF THE RAP HAVE KEPT THE HIGHER 0-3KM MUCAPE OFF TO THE EAST OF THE FORECAST AREA AS WELL...SO AM NOT ANTICIPATING MUCH IN THE WAY OF HAIL TO OCCUR. DUAL POL RADAR ANALYSIS SHOWS SOME BRIGHT BANDING AS WELL AROUND 6-7KFT WITH ALL LIQUID PRECIPITATION LIKELY MAKING IT DOWN TO THE GROUND. && .SHORT TERM...(THIS EVENING THROUGH THURSDAY) ISSUED AT 305 PM CDT WED APR 17 2013 MAIN FORECAST CONCERNS ARE ON HEAVY RAINFALL TONIGHT THROUGH THURSDAY AND LARGE HAIL POTENTIAL THIS EVENING INTO THE OVERNIGHT HOURS. FOCUS THEN TURNS TO PERSISTENT RAINFALL THROUGH THE DAY ON THURSDAY...WITH PRECIPITATION SWITCHING OVER TO SNOW THURSDAY NIGHT. LATEST WATER VAPOR IMAGERY SHOWED A POTENT TROUGH DIGGING INTO THE FOUR CORNERS REGION WITH SOUTHWEST FLOW ALOFT SETTING UP OVER THE UPPER MISSISSIPPI RIVER VALLEY. A MOIST...UNSTABLE AIRMASS WAS ADVECTING NORTHWARD OUT OF THE MIDDLE MISSISSIPPI RIVER VALLEY AND INTERACTING WITH SHORTWAVE ENERGY EMBEDDED IN THE SOUTHWEST FLOW. SHOWERS AND THUNDERSTORMS HAVE BEEN ONGOING ACROSS ACROSS MUCH OF IOWA THROUGH NORTHERN ILLINOIS AND FAR SOUTHWEST WISCONSIN. THE SURGE OF MOIST UNSTABLE AIR CONTINUES ITS NORTHWARD PROGRESSION TONIGHT ON THE NOSE OF A STRONG LOW LEVEL JET. PRECIPITABLE WATER VALUES CLIMB INTO THE 1 TO 1.5 INCH RANGE...WHICH IS 160 TO 230 PERCENT OF NORMAL. ALSO...MUCAPE VALUES INCREASE TO AROUND 1500J/KG ACROSS EXTREME NORTHEAST IOWA AND FAR SOUTHWEST WISCONSIN THIS EVENING INTO THE OVERNIGHT HOURS...WHERE A FEW STORMS COULD PRODUCE LARGE HAIL. WARM CLOUD DEPTHS ALSO INCREASE TONIGHT TO AROUND 3000 M WHICH ALSO IS CONDUCIVE TO HEAVY RAIN POTENTIAL. OVERALL SHEAR IS RATHER WEAK TONIGHT WITH 1 TO 7 KM BULK SHEAR VALUES OF ONLY 15 TO 25 KTS. A STRONG BAROCLINIC ZONE SETS UP ACROSS THE AREA WITH THE WARMEST AIR LOCATED AROUND 925 MB. PLENTY OF SUPPORT FOR SHOWERS AND THUNDERSTORMS TONIGHT ACROSS THE FORECAST AREA WITH THE BAROCLINIC ZONE COLLOCATED WITH THE RIGHT ENTRANCE REGION OF A 250 MB JET. FORECAST MODELS HAVE BEEN TRENDING SLIGHTLY MORE SOUTHEAST WITH THE HEAVIER RAINFALL AMOUNTS KEEPING THE HIGHEST TOTALS GENERALLY SOUTHEAST OF AN OELWEIN IOWA TO MAUSTON WISCONSIN LINE. 2 TO 3 INCHES OF RAINFALL ARE POSSIBLE OVER THESE AREAS WITH 1 TO 2 INCHES POSSIBLE FOR LOCATIONS TO THE NORTH AND WEST. HOWEVER...THIS WILL GREATLY DEPEND UPON WHICH AREAS THE THUNDERSTORMS TRAIN OVER. FLASH FLOODING IS POSSIBLE TONIGHT IF RAINFALL RATES BECOME HIGH ENOUGH. THE HIGHEST CHANCES FOR FLASH FLOODING APPEAR TO BE OVER EXTREME SOUTHWEST WISCONSIN...MAINLY GRANT...CRAWFORD...AND RICHLAND COUNTIES. WILL HAVE TO KEEP A VERY CLOSE EYE ON THIS SITUATION DURING THE OVERNIGHT HOURS. SHOWERS AND ISOLATED THUNDERSTORMS WILL BE ONGOING INTO THURSDAY MORNING THEN THE HEAVIER RAINFALL WILL FINALLY SHIFT SOUTHEAST OF THE AREA BY THURSDAY AFTERNOON AS THE TROUGH LIFTS NORTH INTO EASTERN SOUTH DAKOTA/NEBRASKA AND CLOSES INTO AN UPPER LOW. COLDER AIR FILTERS INTO THE REGION FROM THE WEST ON THURSDAY POTENTIALLY BRING SOME SNOW TO THE FORECAST AREA. A DRY SLOT PUNCHES INTO THE AREA FROM THE SOUTHWEST ON THURSDAY WITH THE FORECAST AREA LOSING DEEP SATURATION. LIGHT RAIN WILL SWITCH OVER TO DRIZZLE AS THE DRY SLOT MOVES IN. THE UPPER LOW IS EXPECTED TO MOVE ACROSS SOUTHWEST MINNESOTA LATE THURSDAY AFTERNOON THEN ADVANCE NORTHEAST INTO EAST CENTRAL MINNESOTA THURSDAY EVENING. A BAND OF SNOW WILL FALL ON THE THE NORTHERN SIDE OF THE LOW TRACK FROM EASTERN SOUTH DAKOTA...INTO CENTRAL MINNESOTA THROUGH NORTHERN WISCONSIN. THE BULK OF THE FORECAST AREA WILL NOT SEE ICE ALOFT SO WHERE TEMPERATURES DROP BELOW FREEZING SOME LIGHT FREEZING DRIZZLE OR FREEZING RAIN IS POSSIBLE...ESPECIALLY THURSDAY EVENING AS SURFACE TEMPERATURES FALL BELOW FREEZING. ICE FINALLY MOVES IN ALOFT THURSDAY NIGHT. ACROSS PORTIONS OF SOUTHEAST MINNESOTA THROUGH NORTH CENTRAL WISCONSIN...PLAN ON SNOW ACCUMULATIONS OF 1 TO 3 INCHES. NORTHEAST IOWA INTO SOUTHWEST AND CENTRAL WISCONSIN SHOULD SEE ACCUMULATIONS OF 1/2 INCH TO AROUND AN INCH. .LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY) ISSUED AT 305 PM CDT WED APR 17 2013 THE LOW IS EXPECTED TO GRADUALLY PROGRESS NORTHEAST INTO WESTERN UPPER MICHIGAN EARLY FRIDAY MORNING. SNOW SHOWERS WILL CONTINUE ACROSS MUCH OF THE AREA FRIDAY MORNING...THEN SWITCHING OVER MAINLY TO RAIN SHOWERS FRIDAY AFTERNOON. PLAN ON BREEZY WEST/NORTHWEST WINDS THURSDAY NIGHT THROUGH FRIDAY WITH A TIGHT PRESSURE GRADIENT OVER THE REGION WITH SPEEDS OF 15 TO 25 MPH WITH GUSTS TO AROUND 35 MPH POSSIBLE...ESPECIALLY DURING THE DAY ON FRIDAY. HIGH TEMPERATURES ON FRIDAY WILL RANGE FROM THE LOWER 30S OVER NORTHERN WISCONSIN TO AROUND 40 ACROSS NORTHEAST IOWA. CHILLY NORTHWEST FLOW CONTINUES ACROSS THE REGION FRIDAY NIGHT THROUGH SATURDAY AS HIGH PRESSURE BUILDS IN. THERE WILL BE A BRIEF BREAK IN PRECIPITATION CHANCES DURING THE DAY ON SATURDAY AHEAD OF ANOTHER TROUGH MOVING IN FROM THE NORTHERN PLAINS. SKIES WILL START OUT MOSTLY SUNNY ON SATURDAY WITH INCREASING CLOUD EXPECTED DURING THE AFTERNOON HOURS. PLAN ON HIGHS ON SATURDAY RANGING FROM AROUND 40 OVER NORTH CENTRAL WISCONSIN TO THE UPPER 40S ACROSS NORTHEAST IOWA. THE HIGH QUICKLY SLIDES OFF TO THE EAST SATURDAY NIGHT. THE TROUGH LOOKS TO MOVE INTO THE UPPER MISSISSIPPI RIVER VALLEY ON SUNDAY SPREADING SHOWERS ACROSS THE AREA. IF THE PRECIPITATION SPREADS IN SATURDAY NIGHT...A WINTER MIX IS POSSIBLE. ACTIVE SOUTHWEST FLOW SETS UP ONCE AGAIN ACROSS THE REGION GOING INTO NEXT WEEK AS A TROUGH DEVELOPS OVER THE CENTRAL CONUS. SEVERAL WAVES EJECT NORTHEAST OUT OF THE TROUGH AND HAVE THE POTENTIAL TO BRING A FEW ROUNDS OF SHOWERS AND THUNDERSTORMS TO THE AREA. MAJOR DIFFERENCES NOTED IN THE TIMING OF THESE WAVES AND EXACTLY HOW THE TROUGH EVOLVES TUESDAY INTO WEDNESDAY SO WILL HAVE TO KEEP A VERY CLOSE WATCH ON THIS SITUATION. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT) ISSUED AT 1143 PM CDT WED APR 17 2013 THE MAIN FOCUS THROUGH TOMORROW NIGHT IS WITH PRECIPITATION TRENDS ALONG WITH THE LIFR TO MVFR FLIGHT CONDITIONS. THE FIRST WAVE OF RAINFALL IS COMING TO AN END WITH A PERIOD OF DRIZZLE POSSIBLE THROUGH THE EARLY MORNING HOURS BEFORE THE NEXT ROUND MOVES IN. THUNDER DOES NOT LOOK LIKELY AS THIS NEXT WAVE MOVES IN...THOUGH FLIGHT CONDITIONS WILL LIKELY REMAIN WHERE THEY ARE AT OR DROP AS THE PRECIPITATION MOVES IN. AFTER THIS WAVE MOVES THROUGH...IT APPEARS THAT DRIZZLE WILL LIKELY BE THE MAIN PRECIPITATION TYPE GOING INTO THE EVENING HOURS BEFORE THE LOW LEVEL TEMPERATURES COOL ENOUGH TO CHANGE IT OVER TO SNOW. RST WILL BE THE FIRST TO CHANGE OVER TO SNOW BY MID EVENING WITH LSE COMING AROUND 6-8Z. && .HYDROLOGY...TONIGHT THROUGH THURSDAY ISSUED AT 305 PM CDT WED APR 17 2013 FLOOD WATCH IN EFFECT THROUGH THURSDAY NIGHT. A VERY MOIST AIR MASS WILL MOVE INTO THE AREA TONIGHT FROM THE MIDDLE MISSISSIPPI RIVER VALLEY...WITH PRECIPITABLE WATER VALUES IN THE 1-1.5 INCH RANGE WHICH IS 160 TO 230 PERCENT ABOVE NORMAL. THIS MOISTURE TRANSPORT AND LIFT...COUPLED WITH UPPER LEVEL DYNAMICS WILL TAP THIS MOISTURE TO PRODUCE 1 TO 3 INCHES OF RAINFALL TONIGHT THROUGH THURSDAY NIGHT. THE HIGHEST AMOUNTS WILL LIKELY BE FOCUSED ACROSS NORTHEAST IA INTO SOUTHWEST WI. ALSO...IF THUNDERSTORMS TRAIN OVER AREAS...FLASH FLOODING IS POSSIBLE TONIGHT INTO EARLY THURSDAY MORNING MAINLY OVER EXTREME NORTHEAST IOWA INTO FAR SOUTHWEST WISCONSIN. WITH MANY RIVERS RUNNING HIGH OR ALREADY IN FLOOD...THIS RAINFALL...ALONG WITH SNOW MELT FROM THE SNOW PACK NORTH OF WISCONSIN HIGHWAY 10 AND STILL SOME FROZEN GROUNDS...WILL HEIGHTEN THE FLOOD THREAT. MANY RIVERS WILL GO INTO...OR BACK INTO...FLOOD. IN ADDITION...THERE WILL BE PONDING OF WATER ON ROADWAYS ALONG WITH STANDING WATER IN LOW LYING AND POOR DRAINAGE AREAS. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...FLOOD WATCH THROUGH LATE THURSDAY NIGHT FOR WIZ042>044-053>055- 061. MN...NONE. IA...FLOOD WATCH THROUGH LATE THURSDAY NIGHT FOR IAZ011-029-030. && $$ UPDATE...HALBACH SHORT TERM...WETENKAMP LONG TERM...WETENKAMP AVIATION...HALBACH HYDROLOGY...WETENKAMP
AREA FORECAST DISCUSSION
NWS CHICAGO/ROMEOVILLE IL
330 AM CDT THU APR 18 2013 .MESOSCALE DISCUSSION... 235 AM CDT A CONTINUED TEXTBOOK SETUP FOR HEAVY RAIN REMAINS IN PLACE EARLY THIS MORNING AND WILL THROUGH LATE MORNING ACROSS THE FORECAST AREA...WITH SIGNIFICANT...EVEN RECORD RIVER FLOODING...A RESPONSE OVER THE NEXT COUPLE DAYS. WHILE AREAL FLOODING REPORTS HAVE BECOME A MORE FAR AND FEW BETWEEN VERY EARLY THIS MORNING...ONLY PART OF THAT IS LIKELY DUE TO A TEMPORARY EASE IN RAINFALL RATES AND MORE OF IT DUE TO THE FACT IT IS DARK OUTSIDE. RAINFALL AMOUNTS ESTIMATED BY RADAR OR OBSERVED THROUGH 1 AM THURSDAY ARE BETWEEN ONE AND A HALF TO FOUR INCHES....WITH THE HIGHEST AMOUNTS IN NORTHWEST LIVINGSTON COUNTY...THE PANHANDLE OF LASALLE COUNTY...AND WESTERN LEE AND OGLE COUNTIES. THE ELEVATED STATIONARY FRONT IS PARKED DIRECTLY OVER THE CWA WITH CONTINUOUS -70C CLOUD TOPS AND ASSOCIATED DEEP CONVECTION TRAINING ENE. IMPRESSIVE LOW-LEVEL CONVERGENCE IS FOCUSED ALONG THIS BOUNDARY AS JUST INFERRED BY THE VAD WIND PROFILER ANALYSIS EARLY THIS MORNING...WITH 70 KTS OF SOUTHERLY 850MB FLOW OVER LSX AND ILX...25 KTS AT LOT...AND NORTHERLY FLOW AT DVN AND MKX. THE REPLENISHMENT OF MOISTURE ON THIS LOW-LEVEL JET IS EXTREME...WITH MOISTURE TRANSPORT MAGNITUDES VERY HIGH. AMBIENT MOISTURE VALUES ARE ALSO PRACTICALLY OFF THE CHARTS...WITH PWAT VALUES RIGHT AT AND POSSIBLY OVER RECORD APRIL LEVELS BASED ON THE HISTORICAL RAOB RECORDS. A TONGUE OF 4C AND HIGHER DEW POINTS AT 700MB ON LAST EVES RAOBS AND CONTINUED TO BE ANALYZED ARE DIRECTED RIGHT INTO THE AREA...WHICH ARE AT LEVELS SHOWN TO REFLECT WARM SEASON RAIN PROCESSES. REFLECTIVITY SINCE MIDNIGHT HAS LOST SOME OF ITS ORGANIZED EMBEDDED STORMS...HOWEVER THE AMOUNT OF 40+ DBZ REMAINS HIGH ALONG WITH LIGHTNING...BOTH REFLECTIVE OF HEAVIER RAINFALL RATES. AGAIN...CONTENT/CONCENTRATION...REPLENISHMENT...AND FOCUS/POOLING OF HEAVY RAINFALL PARAMETERS ARE ALL IN PLACE. LOOKING FORWARD THROUGH 10 AM...THESE PARAMETERS ALMOST ENTIRELY REMAIN IN PLACE. WITH SIX HOUR FLOOD GUIDANCE BEING APPROACHED AND MORE OF THE WATER TURNING INTO RUNOFF IMMEDIATELY...THIS IS LIKELY IN ITSELF TO CAUSE FLOODING ISSUES. WHILE THE BOUNDARY HAS TRIED TO INCH NORTHWARD AND THAT HAS BEEN SEEN SLIGHTLY IN THE RAIN PLACEMENT...AN APPROACHING DEEP SHORT WAVE FROM WESTERN MO WILL LIKELY CONTINUE TO BLOSSOM CONVECTION ACROSS WESTERN IL INTO THE FORECAST AREA. SO AN UPTICK IN CONVECTION IS PROBABLE...AND THUS EVEN SOME HEAVIER RAINFALL RATES FOR A PERIOD. THIS IS MOST FAVORED SOUTH OF INTERSTATE 88 ON CONVECTIVE ALLOWING MODELS. HAVE GONE WITH FLOOD WARNINGS BUT FLASH FLOODING AS THIS PASSES ACROSS MAY BE SEEN...ESPECIALLY IN PARTS OF LA SALLE AND LIVINGSTON COUNTIES...AS WELL AS ANY URBAN AREAS IMPACTED. MTF && .DISCUSSION... 934 PM CDT EVENING/MESOSCALE UPDATE... HAVE CANCELLED REMAINING CONVECTIVE WATCHES...THOUGH FLOODING WILL CONTINUE TO BE A SIGNIFICANT ISSUE THROUGH THURSDAY AND BEYOND. WARM FRONT EXTENDS FROM LOW PRESSURE WAVE OVER WESTERN MISSOURI... NORTHEAST INTO CENTRAL ILLINOIS AND CENTRAL INDIANA AT 02Z. OUTFLOW FROM PERSISTENT ELEVATED THUNDERSTORMS ACROSS IA/NORTHERN IL/IN HAS CONTINUED TO SUPPRESS SURFACE WARM FRONT SOUTH OF THE CWA...AND WILL LIKELY CONTINUE TO DO SO OVERNIGHT BEFORE DEEPENING SURFACE LOW LIFTS FROM MISSOURI INTO NORTHWEST IL IN ASSOCIATION WITH SHORT WAVE LIFTING OUT OF BASE OF UPPER TROUGH OVER THE SOUTHERN PLAINS. UNFORTUNATELY...THIS WILL RESULT IN CONTINUED FORCED ASCENT ATOP CONVECTIVELY ENHANCED FRONTAL ZONE TONIGHT WITHIN A BROAD REGION OF PERSISTENT STRONG WARM/MOIST ADVECTION AHEAD OF DEEP UPPER TROUGH OVER THE PLAINS. ILX 00Z SOUNDING TELLS THE STORY WITH RESPECT TO THE DIMINISHED SEVERE THREAT WITH STRONG LOW LEVEL INVERSION NORTH OF FRONT PREVENTING NEAR SFC-BASED STORMS. RAP GUIDANCE CONTINUES TO DEPICT A GRADIENT IN THE MUCAPE FIELD INCREASING TO 500-1000 J/KG AS YOU MOVE FARTHER SOUTH OF I-80. WHILE EFFECTIVE BULK SHEAR IN EXCESS OF 60 KT WILL CONTINUE TO ALLOW SOME ORGANIZATION FOR ELEVATED CONVECTION NORTH OF WARM FRONT...THE THREAT OF SEVERE WEATHER SHOULD BE LIMITED TO MARGINAL HAIL WITH THE BETTER ORGANIZED STORMS. WHILE THE SEVERE THREAT INTO THE OVERNIGHT HOURS IS RATHER LOW... FLOODING THREAT CONTINUES TO BE SIGNIFICANT INTO THURSDAY. RADAR ESTIMATES AND OBSERVED RAINFALL REPORTS INDICATE THAT MOST AREAS HAVE SEEN UPWARDS OF 0.75 INCHES OF RAIN...WITH MANY AREAS BETWEEN 1.5 AND 2.0 INCHES AND PARTS OF NORTH CENTRAL ILLINOIS IN EXCESS OF 2.5 INCHES. ILX 00Z RAOB DEPICTS PWAT OF 1.38 INCHES...199 PERCENT OF NORMAL...AN INDICATION OF THE VERY MOIST AIR MASS. ADDITIONAL RAINFALL AMOUNTS IN THE 1-2 INCH RANGE ARE VERY LIKELY THROUGH THURSDAY...LIKELY LEADING TO EXTENSIVE FLOODING ON AREA STREAMS AND RIVERS. AERIAL FLOOD WARNINGS REMAIN IN EFFECT INTO MIDDAY THURSDAY...AND MANY RIVER FORECAST SITES ARE HEADED FOR MODERATE TO MAJOR FLOODING. RATZER //PREV DISCUSSION... 342 PM CDT .SHORT TERM...THROUGH FRIDAY... HAZARDOUS WEATHER ISSUES FROM SEVERE THUNDERSTORMS TO EXCESSIVE RAINFALL TO TORNADIC POTENTIAL WILL IMPACT THE REGION THROUGH THURSDAY NIGHT. FOR THE REMAINDER OF THE AFTERNOON AND INTO THIS EVENING...AT 230PM CDT...STRONG THUNDERSTORMS EXTEND ALONG A LINE FROM NEAR WAUKEGAN...SOUTHWEST THROUGH OTTAWA. WEST OF THIS LINE...AN EXTENSIVE AREA OF OVERRUNNING PCPN WITH EMBEDDED THUNDER EXTENDED BACK THROUGH ERN IOWA AND MISSOURI. MUCH OF THE ACTIVITY OVER NRN IL HAS FORMED ALONG AN ELEVATED WARM FRONT...BUT A MORE SOLID LINE HAS DEVELOPED IN THE WARM SECTOR. EXPECT THAT THE THUNDERSTORMS WILL SAG SEWD THROUGH THE EVENING...BRINGING SHOWERS AND THUNDERSTORMS INTO EAST-CENTRAL ILLINOIS AND NORTHWESTERN INDIANA. WITH COPIOUS AMOUNTS OF MOISTURE STREAMING INTO THE REGION...THE STORMS HAVE BEEN VERY EFFICIENT RAIN PRODUCERS...WITH 0.81 INCHES OF RAIN MEASURED AT THE ROCKFORD AIRPORT BTWN 12-18Z THIS MORNING. STORMS HAVE ALSO BEEN MARGINALLY SEVERE WITH NUMEROUS REPORTS OF SMALL HAIL RECEIVED...AND A FEW REPORTS OF LARGER HAIL AS WELL. THIS WILL BE THE CONVECTIVE MODE FOR THE REMAINDER OF THE EVENING AND OVERNIGHT TONIGHT...WITH MODERATE TO HEAVY RAIN AND SMALL HAIL AND OCCASIONAL STRONG WINDS GUSTS. THE FLOODING AND SEVERE WEATHER POTENTIAL WILL RAMP UP EVEN FURTHER TOMORROW AS THE UPPER TROUGH MOVES OUT OVER THE CENTRAL PLAINS AND A SFC LOW DEEPENS. THE SFC LOW WILL SWING THROUGH THE SOUTH HIGH PLAINS EARLY THIS EVENING BEFORE TURNING NEWD...RIPPLING ALONG A QUASI-STATIONARY COLD FRONT AND WARM FRONT. BY THURSDAY MORNING...THE LOW WILL ELONGATE FROM NWRN IL THROUGH NWRN MO...WITH THE SFC WARM FRONT EXTENDING NEWD ACROSS CENTRAL LAKE MICHIGAN. THIS WILL PUT THE CWA FIRMLY IN THE WARM SECTOR. WITH A WIDE OPEN GLFMEX...DEEP LAYER MOISTURE WILL STREAM NWD INTO THE REGION...WITH PWATS EXCEEDING 1.5 INCHES FOR AN EXTENDED PERIOD OF TIME...LEADING TO THE POTENTIAL FOR SIGNIFICANT WIDESPREAD RIVER AND AREAL FLOODING. SEE THE HYDROLOGY SECTION FOR FURTHER DETAILS. THE SEVERE WEATHER MODE SHOULD FOCUS ON STRONG...DAMAGING WINDS AND POSSIBLE TORNADOES. THE LATEST SPC DAY 2 CONVECTIVE OUTLOOK HAS INCREASED THE AREA SOUTH OF A LINE FROM EVANSTON TO PONTIAC TO A MODERATE RISK...WITH THE REMAINDER OF THE AREA IN A SLIGHT RISK. INCREASING HEAT AND MOISTURE...TEMPERATURES REACHING INTO THE LOW TO MIDDLE 70S AND DEW POINTS IN THE LOW TO MIDDLE 60S IN THE WARM SECTOR...INSTABILITY WILL BE AMPLE. WHILE THE GENERAL CONVECTIVE MODE WILL BE LINEAR WITH SMALL LINES AND BOWS POSSIBLE...PRODUCING DAMAGING WINDS...THE MODEL GUIDANCE IS IN GOOD AGREEMENT ON A STRONG LOW LEVEL JET...WITH SWLY WINDS OF 55-65KT ACROSS THE REGION. WHILE SFC WINDS ARE GENERALLY PROGGED TO BE SOUTHERLY...THERE WILL BE OPPORTUNITY FOR SFC WINDS TO BACK A LITTLE MORE EAST OF SOUTH AS THE SFC LOW TRACKS THROUGH NWRN IL AND INTO SRN WI. GIVEN THE AMPLE INSTABILITY...COMBINED WITH CLOCKWISE TURNING HODOGRAPHS...DISCRETE SUPER CELLS MAY DEVELOP OUT IN THE WARM SECTOR AHEAD OF THE LINEAR CONVECTION...WHICH WOULD BRING THE TORNADIC POTENTIAL TO THE REGION. THE POTENTIAL FOR SEVERE WEATHER AND HEAVY RAINFALL WILL CONTINUE UNTIL THE ASSOCIATED COLD FRONT PUSHES THROUGH THE REGION...BRINGING IN MUCH COOLER AIR. THE GUIDANCE IS IN GOOD AGREEMENT ON PUSHING THE FRONT ACROSS THE AREA THURSDAY EVENING. AS THE SFC LOW PUSHES OFF TO THE NORTHEAST...THE UPPER TROUGH WILL ALSO CROSS THE AREA. WITH PLENTY OF RESIDUAL SFC MOISTURE AND COOLER AIR AND CYCLONIC CURVATURE ALOFT...SOME LINGERING INSTABILITY SHOWERS SHOULD PERSIST INTO FRIDAY. HIGHS ON FRIDAY SHOULD DROP BACK INTO THE MIDDLE TO UPPER 40S. KREIN .LONG TERM - SATURDAY THROUGH WEDNESDAY... SPRAWLING SURFACE HIGH PRESSURE TO BUILD INTO THE AREA SATURDAY BEHIND DEPARTING SURFACE LOW/UPPER LEVEL TROUGH. A RETURN TO UNSEASONABLY COOL TEMPS WITH A NEEDED BREAK IN PRECIPITATION WILL BE SHORT LIVED HOWEVER AS THE UPPER FLOW QUICKLY RETURNS SOUTHWESTERLY AS ANOTHER POWERFUL SHORTWAVE TROUGH DIGS INTO WESTERN NORTH AMERICA ON SUNDAY. THIS SHORTWAVE CARVES OUT A TROUGH ACROSS THE MOUNTAIN WEST SUNDAY NIGHT INTO MONDAY. A SERIES OF UPPER LEVEL SHORT WAVE TROUGHS WILL THEN RIPPLE NORTHEAST IN THE SW FLOW ALOFT. SPECIFIC FEATURES ARE POORLY RESOLVED BY MEDIUM RANGE MODELS BUT OVERALL TREND WILL BE A RETURN TO INCREASING MOISTURE AS GULF OPENS BACK UP AGAIN. MEDIUM RANGE MODELS ARE IN FAIRLY GOOD AGREEMENT IN CONCEPT IN SAGGING THE SURFACE FRONTAL BOUNDARY SOUTH ACROSS THE LOCAL AREA MONDAY NIGHT AND STALLING IT OUT TUESDAY SETTING THE STAGE FOR ANOTHER PROLONGED PERIOD OF WET WEATHER TUESDAY INTO WEDNESDAY AS RIPPLES OF LOW PRESSURE LIFT NORTHEAST ALONG THE BOUNDARY. EF && .HYDROLOGY... 350 PM CDT WITH SFC DEW POINTS EXPECTED TO REACH INTO THE LOWER TO MIDDLE 60S AND PWATS POSSIBLY REACHING AS HIGH AS 1.75 INCHES...ANY THUNDERSTORMS THAT DEVELOP WILL BE EFFICIENT RAIN PRODUCERS. BASED ON THE MATT BUNKERS PWAT CLIMATOLOGY...THESE VALUES APPROACH RECORD LEVELS. SO...FLOODING WILL BE A MAJOR CONCERN FOR THE ENTIRE CWA...WITH STORM TOTAL PCPN AMOUNTS OF 2-3 INCHES OVER THE SERN PORTIONS OF THE CWA...GENERALLY SOUTH OF I-80...AND 3-4 INCHES TO THE NORTH. LATEST LOCAL QPF WOULD SUGGEST AN AREA OF PCPN OF 4-5 INCHES IS POSSIBLE ALONG OVER NORTHERN ILLINOIS. THIS REPRESENTS AN INCREASE OVER PREVIOUS FORECASTS...BUT GIVEN THE RECORD LEVEL PWATS FOR AN EXTENDED PERIOD OF TIME...CONFIDENCE IS INCREASING FOR THIS SIGNIFICANT RAINFALL. WITH MANY RIVERS AND STREAMS ARE ALREADY NEAR OR ABOVE MINOR FLOOD STAGE...THIS AMOUNT OF RAIN WILL BRING ADDITIONAL RISES TO MODERATE AND MAJOR FLOOD LEVEL. IN ADDITION TO RIVER FLOODING...AREAL FLOODING OR RURAL...SUBURBAN AND URBAN AREAS IS LIKELY...WITH LOW LYING ROADS AND VIADUCTS FLOODING...AS WELL AS...ROADSIDE DRAINAGE DITCHES AND DRAINAGE PONDS EXCEEDING CAPACITY. AREAS NOT SEEING FLOODING WILL AT LEAST SEE AREAS OF STANDING OR PONDING WATER ON ROADS. KREIN && .AVIATION... //ORD AND MDW CONCERNS...UPDATED 06Z... * WIDESPREAD SHRA AND TS TONIGHT. * PERIODS OF VERY HEAVY RAINFALL THROUGH THE PERIOD...WITH LOW VIS UNDER 2 MILES AT TIMES. * LOW LEVEL WIND SHEAR THIS EARLY THIS MORNING WITH A 50 KT SOUTHERLY JET AT 2,000 FT AGL. * WINDS SHIFTING OUT OF THE SOUTH AFTER 10 UTC WITH WINDS LIKELY GUSTING TO 30 TO 35 KT AT TIMES THROUGH MUCH OF THE DAY. * TIMING OF IMPROVING CONDITIONS BY THIS EVENING. KJB //DISCUSSION...UPDATED 06Z... SHOWERS AND THUNDERSTORMS WILL CONTINUE TO TRAIN NORTHEASTWARD FROM MISSOURI ACROSS NORTHERN ILLINOIS OVERNIGHT TONIGHT. MOISTURE TRANSPORT IS ABSOLUTELY IMPRESSIVE...WITH A 50 TO 60KT LOW LEVEL JET CONTINUALLY PUMPING IN DEEPER MOISTURE. PRECIPITABLE WATER VALUES ARE PROGGED TO INCREASE TO NEAR 1.6 INCHES WHICH IS NEAR RECORD VALUES FOR THIS TIME OF YEAR. THE COMBINATION OF THIS DEEP MOISTURE AND THE THE STRONG DYNAMIC FORCING FROM THIS SYSTEM WILL CONTINUE TO SUPPORT CONVECTIVE ACTIVITY. THERE COULD BE A VERY SHORT BREAK IN THE ACTIVITY AROUND DAYBREAK AT THE EASTERN TERMINALS AS THE WARM FRONT SURGES NORTHWARD THROUGH THE NIGHT. HOWEVER...CONFIDENCE IN THIS IS LOW. ANY BREAK IN THE ACTIVITY...WOULD BE SHORT LIVED...AS ADDITIONAL THUNDERSTORMS WILL MAKE A RETURN BY MID TO LATE MORNING. VERY HEAVY RAINFALL WILL LIKELY ACCOMPANY THESE THUNDERSTORMS. IT ALSO APPEARS THAT SEVERAL HOURS OF ADDITIONAL THUNDERSTORM ACTIVITY IS LIKELY FROM MID TO LATE MORNING THROUGH MUCH OF THE AFTERNOON AS THE CLOUD BEARING FLOW LOOKS TO REMAIN PARALLEL TO THE APPROACHING SURFACE BOUNDARY...WHICH SHOULD RESULT IN TRAINING CELLS. THIS HEAVY RAIN WILL LIKELY REDUCE VISIBILITY UNDER 2 SM AT TIMES...ESPECIALLY DURING THE AFTERNOON. WINDS WILL RAPIDLY INCREASE OUT OF THE SOUTH BY EARLY MORNING AS THE WARM FRONT LIFTS NORTH OF THE AREA. DUE TO THE PRESENCE OF 50 KT OF FLOW ONLY A COUPLE THOUSAND FEET OFF THE GROUND...SOME OF THIS MOMENTUM WILL LIKELY BE MIXED TO THE SURFACE. THUS WINDS WILL LIKELY GUST IN THE LOW TO MID 30 KT RANGE FOR MUCH OF THE DAY. EVEN HIGH WINDS WILL BE POSSIBLE IN WITHIN THE STRONGER STORMS. THUNDERSTORM ACTIVITY SHOULD BEGIN TO ABATE ACROSS THE AREA BY LATE AFTERNOON OR EARLY IN THE EVENING. HOWEVER...THE WINDS WILL SHIFT OUT OF THE WEST SOUTHWEST BEHIND A COLD FRONT BY MID EVENING. THE WINDS WILL LIKELY REMAIN GUSTY UP AROUND 30 KT BEHIND THIS FRONT...BUT THE THREAT FOR THUNDER SHOULD END. KJB //ORD AND MDW CONFIDENCE...UPDATED 06Z... HIGH CONFIDENCE IN PERIODS OF HEAVY THUNDERSTORM RAIN. LOW TO MEDIUM CONFIDENCE ON TIMING OF IMPROVING CONDITIONS LATER TODAY. MODERATE TO HIGH CONFIDENCE IN WINDS. HIGH CONFIDENCE IN IFR AND LOWER VIS AND CIGS IN +TSRA ACTIVITY. KJB //OUTLOOK FOR ORD/MDW FOR 12Z FRIDAY-12Z WEDNESDAY...UPDATED 00Z... FRIDAY...VFR...CHANCE SHRA WITH LOCAL MVFR. SATURDAY...VFR...LAKE BREEZE DEVELOPING AND REACHING CHI TERMINALS EARLY-MID AFTERNOON. SUNDAY...VFR...SLIGHT CHANCE SHRA. MONDAY...VFR...CHANCE SHOWERS. TUESDAY...MVFR LOWERING TO IFR....CHANCE OF SHOWERS. TRS && .MARINE... 328 AM CDT IT WILL BE A MESSY DAY ACROSS THE LAKE TODAY...WITH THUNDERSTORMS...SOME STRONG TO SEVERE...AND STRONG SOUTHERLY WINDS SOUTH...ESPECIALLY FOR THE NEAR SHORE WATERS. THE CURRENT NEAR SHORE GALE WARNING LOOKS GOOD. HOWEVER...IT MIGHT BE HARD TO GET TO GALES UP NEAR THE LAKE COUNTY ILLINOIS NEAR SHORE WATERS. THE STRONGEST SOUTHERLY WINDS UP TO 40 KT IS EXPECTED ACROSS THE INDIANA NEAR SHORE WATERS. ALTHOUGH THE WINDS WILL BE SCREAMING ONLY A COUPLE HUNDRED FEET OFF THE WATER SURFACE...STABLE CONDITIONS OVER THE OPEN WATERS SHOULD LIMIT THE AMOUNT OF THIS STRONG MOMENTUM ABLE TO MIX TO THE WATER SURFACE...WITH THE EXCEPTION OF STRONG WINDS WITH ANY STRONG THUNDERSTORMS. A SURFACE LOW IS EXPECTED TO STRENGTHEN AND CONSOLIDATE ACROSS THE WESTERN GREAT LAKES TODAY AND TONIGHT. THE TRACK OF THIS LOW SHOULD BE SOMEWHERE ACROSS THE NORTHERN HALF OF THE LAKE THIS EVENING. WHERE THIS LOW TRACKS THE WINDS WILL BE VARIABLE IN DIRECTION FOR A PERIOD. THIS SYSTEM WILL PUSH A COLD FRONT ACROSS THE LAKE THROUGH THE NIGHT TONIGHT. STRONG PRESSURE RISES AND COLD AIR ADVECTION SHOULD RESULT IN THE DEVELOPMENT OF WESTERLY GALES VERY LATE TONIGHT AND DURING THE DAY ON FRIDAY. IT CURRENTLY APPEARS THAT GALES OF 35 TO 40 KT ARE THE FAVORED WIND SPEEDS. THESE STRONG WINDS WILL ALSO AFFECT THE NEAR SHORE WATERS AS WELL. I ISSUED A GALE WARNING FOR THE OPEN WATERS FOR FRIDAY AND FRIDAY EVENING. WINDS SHOULD ABATE ON SATURDAY AS A SURFACE RIDGE OF HIGH PRESSURE BUILDS ACROSS THE GREAT LAKES. HOWEVER...THE WEATHER PATTERN LOOKS TO BECOME ACTIVE AGAIN NEXT WEEK...WITH THE POTENTIAL FOR ANOTHER SIGNIFICANT SYSTEM TO AFFECT THE GREAT LAKES REGION BY THE MIDDLE OF NEXT WEEK. KJB && .LOT WATCHES/WARNINGS/ADVISORIES... IL...FLOOD WATCH...ILZ003-ILZ004-ILZ005-ILZ006-ILZ008-ILZ010-ILZ011- ILZ012-ILZ013-ILZ014-ILZ019-ILZ020-ILZ021-ILZ022-ILZ023- ILZ032-ILZ033-ILZ039 UNTIL 7 AM FRIDAY. WIND ADVISORY...ILZ023-ILZ032-ILZ033-ILZ039...10 AM THURSDAY TO 7 PM THURSDAY. IN...FLOOD WATCH...INZ001-INZ002-INZ010-INZ011-INZ019 UNTIL 7 AM FRIDAY. WIND ADVISORY...INZ001-INZ002-INZ010-INZ011-INZ019...10 AM THURSDAY TO 7 PM THURSDAY. LM...GALE WARNING...LMZ080-LMZ261-LMZ362-LMZ364-LMZ366-LMZ563-LMZ565- LMZ567-LMZ669-LMZ671-LMZ673-LMZ675-LMZ777-LMZ779-LMZ868- LMZ870-LMZ872-LMZ874-LMZ876-LMZ878...4 AM FRIDAY TO 4 AM SATURDAY. GALE WARNING...LMZ740-LMZ741-LMZ742...7 AM THURSDAY TO 7 PM THURSDAY. GALE WATCH...LMZ740-LMZ741-LMZ742-LMZ743-LMZ744-LMZ745...4 AM FRIDAY TO 10 PM FRIDAY. SMALL CRAFT ADVISORY...NEARSHORE WATERS UNTIL 7 AM THURSDAY. GALE WARNING...LMZ743-LMZ744-LMZ745...7 AM THURSDAY TO 10 PM THURSDAY. && $$
AREA FORECAST DISCUSSION
NWS NORTH PLATTE NE
708 AM CDT THU APR 18 2013 .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 359 AM CDT THU APR 18 2013 THE PV1.5 ANOMALY CURRENTLY ACROSS WRN KS HAS SPAWNED ANOTHER LOCALLY STRONG BUT NARROW BAND OF MODERATE SNOW. THIS BAND OF SNOW WILL MOVE WITH THE ANOMALY AND THE RUC LIFTS IT NORTH NORTHEAST VERY QUICKLY THIS MORNING. ACCUMULATING SNOWFALL COULD BE OUT OF THE FCST BY 15Z AND HIGHEST ACCUMULATIONS...PERHAPS 4 INCHES...SHOULD FOCUS ALONG AND EAST OF HIGHWAY 281 INCLUDING CUSTER COUNTY. IT IS CLEAR THE DRY AIR IS WINNING OUT ON THIS SYSTEM AS THE SNOW HAS SHUT OFF WEST OF HIGHWAY 61 ACROSS WRN NEB. THE RAP IS SUGGESTING SOME SNOW SHOWER ACTIVITY TODAY AS THE 500 MB COLD POOL MOVES OVERHEAD...ESPECIALLY TO THE LEE OF THE BLACK HILLS WHERE A CONVERGENCE ZONE COULD DEVELOP. THE MODELS DO NOT FCST THE LOCATION OF CONVERGENCE VERY WELL BUT THE RAP...GEM REG AND NAM ARE SUGGESTING THE PANHANDLE SOUTH SOUTHEAST OF CHADRON. THE FCST TODAY JUST BROAD BRUSHES ISOLATED SNOW SHOWERS WEST BUT TAPERS THE SNOW OFF IN THE NORTHEAST. THE NAM AND RAP SHOW SKIES CLEARING AROUND NIGHTFALL TONIGHT. THE ARCTIC HIGH WILL BUILD THROUGH THE CNTL ROCKIES TONIGHT WHILE LOW PRESSURE SWIRLS ACROSS THE UPPER MIDWEST ALLOWING FOR WINDS TO STAY UP A BIT. THIS MIGHT HOLD LOWS NEAR 20 AND RADIATIONAL CONDITIONS WILL BE LESS THAN IDEAL. THE SNOW FCST IS FOR 1 TO 3 INCHES OF NEW SNOW TODAY. THIS USES THE RUC QPF BUT REDUCES IT BY 70 PERCENT IN MOST AREAS AND APPLIES A 10 TO 1 RATIO. THIS IS THE SAME AS REDUCING THE QPF BY 50 PERCENT AND USING A 14 TO 1 RATIO WHICH MIGHT BE CLOSER TO REAL LIFE. .LONG TERM...(FRIDAY THROUGH WEDNESDAY) ISSUED AT 359 AM CDT THU APR 18 2013 FRIDAY WILL SEE HIGHS REBOUND BACK INTO THE 40S...NEAR 50 FOR FAR SW NEB. HOWEVER NORTHWEST FLOW WILL BRING A DISTURBANCE ACROSS THE NORTHERN PLAINS. MODELS SHOW SOME DECENT LOW LEVEL SATURATION...WITH DRY AIR ALOFT. COULD SEE SOME DRIZZLE OR SPRINKLES DURING THE DAY...HOWEVER JUST NOT ENOUGH CONFIDENCE TO ADD YET...MAINLY DUE TO CURRENT CONDITIONS ON THE DRIER SIDE. SATURDAY AND SUNDAY THE COUPLE MORE OF QUICK MOVING DISTURBANCES WILL RIDE ACROSS NORTHERN/CENTRAL PLAINS. BETTER ENERGY IS TO THE NORTH...HOWEVER WILL SEE THE SOUTHERN EDGE MOVE ACROSS THE CWA. EXPECTING TO CONTINUE TO SEE COLD AIR ALOFT SPREAD DOWN FROM CANADA...HOWEVER LESS MOISTURE TO WORK WITH IN THE LOWER LEVELS. STRONGER COLD FRONT SUNDAY WITH GFS DEVELOPING SOME MARGINAL CAPE...COUPLE HUNDRED J/KG...AND BARELY NEG LI/S AHEAD OF THE FRONT. HAVE INTRODUCED ISOLD THUNDER DURING THE DAY...WHICH MAY LINGER INTO THE EVENING DEPENDING ON EXACT TIMING OF THE FRONT AND MOISTURE. MONDAY AND TUESDAY ARE EXPECTED TO BE ANOTHER WELL BELOW NORMAL COUPLE OF DAYS. GFS CAME IN COOLER...WHICH IS CLOSER TO THE COOLER EC. HIGHS LIKELY IN THE 40S...WHICH WOULD NORMALLY BE A STRETCH TO GO SO FAR BELOW NORMAL /NORMAL IS 60S/ THIS FAR OUT. HOWEVER WITH THE LAST TWO SYSTEMS SHOWING HOW EASY IT IS TO ACCOMPLISH THIS APRIL...WILL CONTINUE TO BE SOME 20 PLUS DEGREES BELOW NORMAL FOR HIGHS. LOWS IN THE 20S SO LIGHT PRECIP IS EXPECTED TO BE RAIN OR A MIX DURING THE DAY AND A MIX TO SNOW OVERNIGHT. WEDNESDAY WILL SEE THE START OF ANOTHER WARMUP AND DRY CONDITIONS. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z FRIDAY MORNING) ISSUED AT 705 AM CDT THU APR 18 2013 SNOW CONTINUING OVER NORTH CENTRAL AND NORTHEAST NEBRASKA WILL CONTINUE BRINGING AREAS OF CEILINGS BELOW 1000 FEET MSL AND VISIBILITY AS LOW AS 1/2SM. THE SNOW WILL GRADUALLY DIMINISH TODAY ALONG AND EAST OF AN ANW-BBW LINE. OTHER PARTS OF WESTERN NEBRASKA INCLUDING LBF AND TIF WILL HAVE CEILINGS 1500-2500 FEET AGL AND VISIBILITY OF 3SM OR LOWER UNTIL LATE THIS MORNING. WIND IN CENTRAL AND WESTERN NEBRASKA WILL INCREASE TODAY AND BECOME 310-340 AT 22-26G31-35KT. && .LBF WATCHES/WARNINGS/ADVISORIES... WINTER WEATHER ADVISORY UNTIL 4 PM CDT THIS AFTERNOON FOR NEZ006>010-026>029-038. && $$ SHORT TERM...CDC LONG TERM...MASEK AVIATION...SPRINGER
AREA FORECAST DISCUSSION
NWS NORTH PLATTE NE
1228 AM CDT THU APR 18 2013 .SYNOPSIS... ISSUED AT 256 PM CDT WED APR 17 2013 AT 19Z...WATER VAPOR IMAGERY CONTINUED SHOWING A DEEP TROUGH ACROSS THE WESTERN STATES WITH THE AXIS RUNNING FROM LAKE WINNIPEG THROUGH MONTANA...WYOMING AND UTAH TO SOUTHERN NEVADA. AT THE SURFACE...THERE WAS A STRENGTHENING SURFACE LOW OVER CENTRAL NEW MEXICO. A FRONT EXTENDED FROM THAT LOW ACROSS THE TEXAS RED RIVER AREA THROUGH EASTERN OKLAHOMA AND SOUTHEAST KANSAS TO CENTRAL MISSOURI. THERE WAS ALSO AND INVERTED TROUGH OR OCCLUDED FRONT EXTENDING FROM THE NEW MEXICO LOW INTO SOUTH CENTRAL COLORADO. && .UPDATE... ISSUED AT 948 PM CDT WED APR 17 2013 A NEW FORECAST IS OUT USING THE RAP AND ARF MODELS. STILL LOOKS LIKE AREAS EAST OF HIGHWAY 83 WILL MEASURE 3 TO 6 INCHES BY THURSDAY AFTN. WEST OF 83...THE SNOW IS SHOWING SIGNS OF WINDING DOWN. SATELLITE AND THE RAP MODEL SHOW TO DISTINCT AREAS OF POTENTIAL VORTICITY. ONE NEAR DODGE CITY WHICH IS IGNITING CONVECTION. SLEET AND SNOW SHOULD DEVELOP AS THIS AREA MOVES NORTH NORTHEAST BRUSHING EASTERN ZONES WITH SNOW AFTER MIDNIGHT. MOST OF THIS SNOW SHOULD END UP ACROSS CNTL NEB. THE SECOND AREA OF POTENTIAL VORTICITY LIES ACROSS ERN NEW MEXICO. THIS ARE IS EXPECTED TO IGNITE A SECOND BAND OF MODERATE SNOW ALONG AND EAST OF HIGHWAY 83 LATE TONIGHT AND THURSDAY. MOST OF THIS SNOW SHOULD FALL EAST OF HIGHWAY 83. THUS 2 TO 4 INCHES IS EXPECTED WEST OF HIGHWAY 83 WITH THE EMPHASIS ON 2 INCHES GIVEN THE RADAR TRENDS AND SIGNS OF DRY AIR WORKING SOUTHWARD THROUGH SOUTH DAKOTA. WINDS ARE ABOUT 10 KTS LESS THAN PREVIOUSLY FORECAST BUT STRONGEST WINDS COULD DEVELOP LATE THURSDAY MORNING AND AFTERNOON. THE REST OF THE FORECAST IS ON TRACK. && .SHORT TERM...(THIS EVENING THROUGH THURSDAY) ISSUED AT 256 PM CDT WED APR 17 2013 AREAS OF FREEZING DRIZZLE THIS MORNING LOOKS TO BE TRANSITIONING MORE TO LIGHT FOG AND VERY LIGHT SNOW ACROSS THE CENTRAL SANDHILLS AND EASTERN AREAS THIS AFTERNOON AS COLDER AIR CONTINUES TO SETTLE SOUTHWARD. ONLY AREA WITH LIGHT SNOW ACCUMULATIONS THIS AFTERNOON IS ACROSS SHERIDAN AND NORTHWEST CHERRY COUNTY. THE 700MB CLOSED LOW WAS LOCATED IN CENTRAL COLORADO AT 18Z TODAY. SNOW EXTENDS ACROSS THE COLORADO MOUNTAINS AND EASTERN FOOTHILLS INTO SOUTHEAST WYOMING THE NEBRASKA PANHANDLE AND SOUTHWEST SOUTH DAKOTA. MEANWHILE SHOWERS AND THUNDERSTORMS HAVE DEVELOPED ACROSS CENTRAL AND NORTHEAST KANSAS INTO FAR SOUTHEAST NEBRASKA SOUTHWEST IOWA. STRONG STORMS DEVELOPING WEST CENTRAL OKLAHOMA/SOUTH CENTRAL KANSAS. THE UPPER LOW IS FORECAST TO LIFT NORTHEAST AS A POSITIVELY TILT INTO NORTHWEST KANSAS/CENTRAL NEBRASKA BY 06Z THURSDAY. MODERATE TO LOCALLY HEAVY SNOW IS FAVORED TO DEVELOP ALONG AND WEST OF THE UPPER LOW. THE GFS IS AND HAS CONSISTENTLY BEEN MORE ROBUST WITH QPFS THE PAST SEVERAL RUNS...WHILE THE NAM HAS SLOWLY BEEN COMING INTO LINE. ONE CONCERN WILL BE CONVECTION TO OUR SOUTHEAST THIS AFTERNOON/TONIGHT WHICH MAY LIMIT MOISTURE TRANSPORT INTO WESTERN NEBRASKA TONIGHT INTO THURSDAY. HAVE TAKEN THIS INTO ACCOUNT WITH THE FORECAST. SECOND CONCERN WILL BE WINDS WITH NORTH WINDS THIS EVENING 20 TO 35 MPH BACKING TO THE NORTHWEST AFTER MIDNIGHT. THEN ON THURSDAY...NORTHWEST WINDS TO INCREASE TO 25 TO 35 MPH WITH GUSTS TO 40 MPH. WINDS TONIGHT AND THURSDAY WILL CAUSE BLOWING AND DRIFTING SNOW ACROSS THE SOUTHERN AND EASTERN HALF OF THE AREA THROUGH THURSDAY. IN THE WINTER WEATHER ADVISORY AREA...SNOWFALL AMOUNTS TONIGHT AND THURSDAY RANGE FROM 3 TO 5 INCHES SOUTHWEST NEBRASKA...4 TO 7 INCHES EAST OF VALENTINE THROUGH BROKEN BOW. ACROSS THE NORTHWEST AROUND 6 INCHES POSSIBLE. WILL CARRY ALL EXISTING WINTER STORM WARNINGS AND ADVISORY THROUGH TONIGHT. ONLY CHANGE WAS TO EXTEND THE ADVISORY THROUGH THE DAY THURSDAY ACROSS THE EASTERN HALF OF THE FORECAST AREA DUE TO THE SLOWER TIMING OF THE SYSTEM AND EXPECTED WRAP AROUND SNOW. THE STRONG NORTHWEST WINDS WITH HIGH TEMPERATURES ONLY IN THE LOWER 30S MOST AREAS THURSDAY TO RESULT IN WIND CHILL VALUES OF 5 TO 15 ABOVE IN THE MORNING AND 15 TO 20 DEGREES IN THE AFTERNOON. .LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY) ISSUED AT 256 PM CDT WED APR 17 2013 WARM AIR RETURNING FROM THE SOUTHWEST FRIDAY EVENING WILL GENERATE SOME DEEP ISENTROPIC UPGLIDE OF NEARLY SATURATED AIR IN THE 290-310K LAYER. THE BOUNDARY LAYER IS PRETTY DRY THOUGH...SO SIGNIFICANT PRECIPITATION IS NOT LIKELY. A FRONT SETTLES INTO THE NORTHERN PLAINS SATURDAY AND THEN BEGINS MOVING NORTH AND SOUTH ALTERNATELY. THIS WILL KEEP SOME CHANCE OF PRECIPITATION IN CENTRAL AND WESTERN NEBRASKA SATURDAY EVENING THROUGH TUESDAY. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT) ISSUED AT 1227 AM CDT THU APR 18 2013 MIXED IFR/MVFR/VFR CONTINUES OVERNIGHT WITH IMPROVEMENT TO VFR/MVFR FROM WEST TO EAST. THIS PROCESS IS ALREADY UNDERWAY ACROSS WRN NEB. THE RAP IS SUGGESTING LOCAL IFR ACROSS WRN NEB THURSDAY AFTERNOON AS SCATTERED -SHSN DEVELOP. EAST OF HIGHWAY 83...IFR/MVFR MAY CONTINUE THROUGH THURSDAY AFTERNOON IN SNOW AND BLSN. IMPROVEMENT TO WIDESPREAD VFR IS EXPECTED ALL AREAS BETWEEN 00Z THURSDAY AND 06Z THURSDAY EVENING AS THE UPPER LEVEL LOW ACROSS THE SRN ROCKIES EJECTS INTO THE MIDWEST. && .LBF WATCHES/WARNINGS/ADVISORIES... WINTER WEATHER ADVISORY UNTIL 7 AM CDT /6 AM MDT/ THIS MORNING FOR NEZ004-022>024-035-036-056>058-069-070-094. WINTER WEATHER ADVISORY UNTIL 1 PM CDT THIS AFTERNOON FOR NEZ005- 025-037-059-071. WINTER WEATHER ADVISORY UNTIL 7 PM CDT THIS EVENING FOR NEZ006>010-026>029-038. && $$ UPDATE...CDC SYNOPSIS...SPRINGER SHORT TERM...ROBERG LONG TERM...SPRINGER AVIATION...CDC
AREA FORECAST DISCUSSION
NWS BURLINGTON VT
740 AM EDT THU APR 18 2013 .SYNOPSIS... A WARM FRONT WILL APPROACH THE REGION TODAY...AND THEN MOVE NORTH INTO CANADA TONIGHT. IT WILL BE WARM AND BECOMING WINDY TODAY AND FRIDAY AS GUSTY SOUTHERLY WINDS WILL BRING MUCH WARMER AIR TO THE NORTH COUNTRY...WITH HIGHS IN THE 70S ON FRIDAY. A COLD FRONT WILL MOVE INTO THE REGION LATE FRIDAY AFTERNOON AND THEN MOVE ACROSS THE AREA FRIDAY NIGHT...BRINGING RAIN SHOWERS TO THE NORTH COUNTRY. IT WILL BE MUCH COOLER AND BREEZY ON SATURDAY. A HIGH PRESSURE AREA OVER THE GREAT LAKES WILL BUILD INTO THE REGION SATURDAY NIGHT AND SUNDAY. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... AS OF 740 AM EDT THURSDAY...COMPOSITE RADAR LOOP SHOWING SOME RETURNS ACROSS NORTHERN NEW YORK AND THE NORTHERN CHAMPLAIN VALLEY AT THIS TIME. HAVE RAISED POPS TO SLIGHT CHANCE FOR SHOWERS FOR TODAY...BUT NOT EXPECTING MUCH IF ANY IN THE WAY OF ACCUMULATIONS...AS TEMPERATURE/DEW POINT SPREAD WILL INCREASE DURING THE DAY. EXPECTING MAINLY SPRINKLES TODAY...IF ANYTHING REACHES THE SURFACE. OTHERWISE...THE FORECAST IS IN GOOD SHAPE. PREVIOUS DISCUSSION FROM 451 AM EDT THURSDAY...WARM FRONT WILL LIFT NORTHEAST THROUGH THE REGION TODAY BRINGING CLOUDS...ALONG WITH A CHANCE OF RAIN SHOWERS MAINLY OVER THE SAINT LAWRENCE VALLEY AND THE ADIRONDACKS. TEMPERATURES WILL CLIMB TO THE UPPER 50S TO LOWER 60S TODAY. SURFACE PRESSURE GRADIENT TO TIGHTEN THIS AFTERNOON...SO COULD SEE SOME SOUTHERLY WIND GUSTS UP TO 40 MPH POSSIBLE THIS AFTERNOON FROM THE CHAMPLAIN VALLEY WESTWARD ACROSS NORTHERN NEW YORK. MOS POPS LOOK TOO HIGH FOR TODAY...SO HAVE LOWERED THEM QUITE A BIT. && .SHORT TERM /6 PM THIS EVENING THROUGH SATURDAY/... AS OF 451 AM EDT THURSDAY...THE WARM FRONT WILL LIFT NORTHEAST INTO QUEBEC TONIGHT. HAVE GONE WITH A DRY FORECAST FOR TONIGHT... AS THE BEST LIFT ASSOCIATED WITH THE WARM FRONT WILL BE IN CANADA. THUS...HAVE GREATLY LOWERED MOS POPS FOR TONIGHT. GUSTY SOUTHERLY WINDS WILL CONTINUE INTO TONIGHT...AND THIS WILL HELP TO KEEP TEMPERATURES UP TONIGHT. HAVE GONE SEVERAL DEGREES WARMER THAN THE GFS MOS GUIDANCE FOR MIN TEMPERATURES TONIGHT. ON FRIDAY...GUSTY SOUTHERLY WINDS WILL CONTINUE AS SURFACE PRESSURE GRADIENT REMAINS TIGHT ACROSS THE REGION. SOUTHERLY WIND GUSTS COULD APPROACH 50 MPH FRIDAY AFTERNOON ACROSS WESTERN VERMONT AND NORTHERN NEW YORK. GIVEN THAT THIS WILL OCCUR LATE IN THE THIRD PERIOD OF THE FORECAST...HAVE HELD OFF ON ANY WIND ADVISORY AT THIS TIME. WILL LET LATER SHIFTS REVIEW LATER GUIDANCE BEFORE MAKING ANY DECISION ON A WIND ADVISORY. HAVE MENTIONED THIS POSSIBILITY IN THE HAZARDOUS WEATHER OUTLOOK PRODUCT. EXPECTING FRIDAY TO START OUT AS A MAINLY DRY DAY ACROSS THE REGION WITH TEMPERATURES CLIMBING INTO THE 70S FRIDAY AFTERNOON. THE BEST CHANCE FOR RAIN SHOWERS FOR LATER FRIDAY AFTERNOON WILL BE ACROSS THE SAINT LAWRENCE VALLEY AND THE ADIRONDACKS IN NORTHERN NEW YORK...AS THE COLD FRONT MOVES INTO THE REGION. HAVE HELD OFF ON BRINGING RAIN SHOWERS FOR THE CHAMPLAIN VALLEY AND VERMONT UNTIL FRIDAY NIGHT. MODELS SHOW A MID LEVEL DRY SLOT WILL WORK INTO THE REGION LATE FRIDAY NIGHT...SO EXPECTING ANY RAIN SHOWER ACTIVITY WILL COME TO AN END BEFORE DAYBREAK ON SATURDAY. MUCH COOLER TEMPERATURES WILL BE OVER THE REGION ON SATURDAY. HAVE PUT IN SLIGHT CHANCE POPS OVER THE MOUNTAINS FOR RAIN SHOWERS ON SATURDAY. && .LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/... AS OF 510 AM EDT THURSDAY...OVERALL GOOD AGREEMENT BTWN GFS/ECMWF FOR THE WEEKEND AND INTO EARLY NEXT WK...THEN UNCERTAINTY DEVELOPS AS PATTERN BECMG MORE ACTIVE. SFC HIGH PRES WL RESULT IN MAINLY CLR SKIES AND DRY CONDITIONS FOR SUNDAY/MONDAY. GIVEN DEEP DRY AIRMASS ACRS THE NE CONUS...EXPECT LARGE SWINGS IN DIURNAL TEMPS FROM LOWS SAT NIGHT/SUNDAY NIGHT TO HIGHS ON SUNDAY/MONDAY. TEMPS WL BE 4 TO 8 DEGREES BLW NORMAL. THE 00Z ECMWF HAS TRENDED TWD THE GFS/GFS ENSEMBLE AND GEM FOR TUESDAY...WITH TRACK WELL TO OUR SOUTH AND EAST. GIVEN UNCERTAINTY WITH ANTICYCLONIC FLW AROUND HIGH PRES AND POTENTIAL FOR SOME MOISTURE TO ADVECT BACK INTO OUR CENTRAL/EASTERN CWA WL MENTION SCHC/LOW CHC POPS. ALSO...THIS WL CONT WITH PREVIOUS FCSTER THINKING. OTHERWISE...MODELS ARE IN RELATIVELY GOOD AGREEMENT WITH NEXT LARGE SCALE SYNOPTIC SYSTEM IMPACTING OUR REGION LATE WEDS INTO THURS. ONCE AGAIN SFC LOW PRES WL TRACK TO OUR WEST...PLACING OUR CWA IN THE WARM SECTOR BY WEDS ALONG CHCS FOR PRECIP WED AFTN INTO THURS. TEMPS WL BE NEAR NORMAL TUES AND ABOVE NORMAL FOR WEDS INTO THURS. && .AVIATION /12Z THURSDAY THROUGH MONDAY/... THROUGH 12Z FRIDAY...DEVELOPING STRONG SOUTHERLY SFC WINDS WILL CREATE AREAS OF MODERATE TURBULENCE AND AREAS OF POTENTIAL LLVL WIND SHEAR TODAY. AVIATION CHALLENGE THRU THIS EVENING WL BE PLACEMENT OF LIGHT RAIN SHOWERS THIS MORNING...FOLLOWED BY GUSTY WINDS. CRNT SFC ANALYSIS SHOWS HIGH PRES LOCATED OVER NORTHERN NEW ENGLAND WITH A SFC WARM FRNT LIFTING ACRS NORTHERN NY ATTM. THIS FRNT AND ASSOCIATED RIBBON OF DEEPER MOISTURE WL LIFT ACRS NORTHERN NY TAF SITES BTWN 12Z AND 15Z THIS MORNING. BASED OFF THE RAP 13 HAVE TEMPO A PERIOD OF -SHRA FOR MSS/SLK EARLY THIS MORNING. WL USE VCSH AT PBG/BTV BTWN 13-16Z. IN ADDITION...SFC GRADIENT WL INCREASE WITH GUSTY SOUTH WINDS ANTICIPATED. SOUNDINGS SHOW WIND GUSTS POTENTIAL BTWN 25 AND 30 KNTS THIS AFTN...AS SFC HEATING OCCURS. RAP SOUNDINGS SHOW GUST POTENTIAL BTWN 35 ADN 40 KNTS AT MSS/BTV/SLK BTWN 19Z AND 02Z TODAY. VFR CONDITIONS WL PREVAIL THRU TODAY. NAM AND RAP CONTS TO SHOW SOME LLVL RH/CLOUDS INCREASING THIS EVENING WITH THE POTENTIAL FOR SOME MVFR CIGS IN A STRATO CUMULUS DECK...NOT ANTICIPATING FOG/BR GIVEN LLVL WIND PROFILES...WL USE SCATTERED 1200 TO 1500 FT TO SHOW THIS POTENTIAL OUTLOOK 12Z FRIDAY THROUGH MONDAY... GUSTY SOUTHERLY WINDS WL CONT ON FRIDAY AS SFC LOW PRES TRACKS FROM THE GREAT LAKES INTO CENTRAL CANADA. A BROKEN LINE OF SHOWERS WL IMPACT OUR TAF SITES LATE FRIDAY INTO SATURDAY WITH A BRIEF PERIOD OF MVFR CONDITIONS POSSIBLE IN THE HEAVIER SHOWERS. OTHERWISE...SFC HIGH PRES AND VFR CONDITIONS PREVAIL SAT THRU EARLY NEXT WEEK. && .HYDROLOGY... AS OF 451 AM EDT THURSDAY...WARMER TEMPERATURES TODAY AND FRIDAY WILL RESULT IN MELTING SNOW ACROSS THE HIGHER ELEVATIONS OF THE ADIRONDACKS AND GREEN MOUNTAINS. RUNOFF FROM THIS SNOW MELT WILL LEAD TO SOME SHARP RISES ON AREA RIVERS TODAY THROUGH FRIDAY. HOWEVER...NO FLOODING IS EXPECTED AT THIS TIME. && .BTV WATCHES/WARNINGS/ADVISORIES... VT...NONE. NY...NONE. && $$ SYNOPSIS...WGH NEAR TERM...WGH SHORT TERM...WGH LONG TERM...TABER AVIATION...TABER HYDROLOGY...WGH
AREA FORECAST DISCUSSION
NWS BURLINGTON VT
714 AM EDT THU APR 18 2013 .SYNOPSIS... A WARM FRONT WILL APPROACH THE REGION TODAY...AND THEN MOVE NORTH INTO CANADA TONIGHT. IT WILL BE WARM AND BECOMING WINDY TODAY AND FRIDAY AS GUSTY SOUTHERLY WINDS WILL BRING MUCH WARMER AIR TO THE NORTH COUNTRY...WITH HIGHS IN THE 70S ON FRIDAY. A COLD FRONT WILL MOVE INTO THE REGION LATE FRIDAY AFTERNOON AND THEN MOVE ACROSS THE AREA FRIDAY NIGHT...BRINGING RAIN SHOWERS TO THE NORTH COUNTRY. IT WILL BE MUCH COOLER AND BREEZY ON SATURDAY. A HIGH PRESSURE AREA OVER THE GREAT LAKES WILL BUILD INTO THE REGION SATURDAY NIGHT AND SUNDAY. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... AS OF 451 AM EDT THURSDAY...A WARM FRONT WILL LIFT NORTHEAST THROUGH THE REGION TODAY BRINGING CLOUDS...ALONG WITH A CHANCE OF RAIN SHOWERS MAINLY OVER THE SAINT LAWRENCE VALLEY AND THE ADIRONDACKS. TEMPERATURES WILL CLIMB TO THE UPPER 50S TO LOWER 60S TODAY. SURFACE PRESSURE GRADIENT TO TIGHTEN THIS AFTERNOON...SO COULD SEE SOME SOUTHERLY WIND GUSTS UP TO 40 MPH POSSIBLE THIS AFTERNOON FROM THE CHAMPLAIN VALLEY WESTWARD ACROSS NORTHERN NEW YORK. MOS POPS LOOK TOO HIGH FOR TODAY...SO HAVE LOWERED THEM QUITE A BIT. && .SHORT TERM /6 PM THIS EVENING THROUGH SATURDAY/... AS OF 451 AM EDT THURSDAY...THE WARM FRONT WILL LIFT NORTHEAST INTO QUEBEC TONIGHT. HAVE GONE WITH A DRY FORECAST FOR TONIGHT... AS THE BEST LIFT ASSOCIATED WITH THE WARM FRONT WILL BE IN CANADA. THUS...HAVE GREATLY LOWERED MOS POPS FOR TONIGHT. GUSTY SOUTHERLY WINDS WILL CONTINUE INTO TONIGHT...AND THIS WILL HELP TO KEEP TEMPERATURES UP TONIGHT. HAVE GONE SEVERAL DEGREES WARMER THAN THE GFS MOS GUIDANCE FOR MIN TEMPERATURES TONIGHT. ON FRIDAY...GUSTY SOUTHERLY WINDS WILL CONTINUE AS SURFACE PRESSURE GRADIENT REMAINS TIGHT ACROSS THE REGION. SOUTHERLY WIND GUSTS COULD APPROACH 50 MPH FRIDAY AFTERNOON ACROSS WESTERN VERMONT AND NORTHERN NEW YORK. GIVEN THAT THIS WILL OCCUR LATE IN THE THIRD PERIOD OF THE FORECAST...HAVE HELD OFF ON ANY WIND ADVISORY AT THIS TIME. WILL LET LATER SHIFTS REVIEW LATER GUIDANCE BEFORE MAKING ANY DECISION ON A WIND ADVISORY. HAVE MENTIONED THIS POSSIBILITY IN THE HAZARDOUS WEATHER OUTLOOK PRODUCT. EXPECTING FRIDAY TO START OUT AS A MAINLY DRY DAY ACROSS THE REGION WITH TEMPERATURES CLIMBING INTO THE 70S FRIDAY AFTERNOON. THE BEST CHANCE FOR RAIN SHOWERS FOR LATER FRIDAY AFTERNOON WILL BE ACROSS THE SAINT LAWRENCE VALLEY AND THE ADIRONDACKS IN NORTHERN NEW YORK...AS THE COLD FRONT MOVES INTO THE REGION. HAVE HELD OFF ON BRINGING RAIN SHOWERS FOR THE CHAMPLAIN VALLEY AND VERMONT UNTIL FRIDAY NIGHT. MODELS SHOW A MID LEVEL DRY SLOT WILL WORK INTO THE REGION LATE FRIDAY NIGHT...SO EXPECTING ANY RAIN SHOWER ACTIVITY WILL COME TO AN END BEFORE DAYBREAK ON SATURDAY. MUCH COOLER TEMPERATURES WILL BE OVER THE REGION ON SATURDAY. HAVE PUT IN SLIGHT CHANCE POPS OVER THE MOUNTAINS FOR RAIN SHOWERS ON SATURDAY. && .LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/... AS OF 510 AM EDT THURSDAY...OVERALL GOOD AGREEMENT BTWN GFS/ECMWF FOR THE WEEKEND AND INTO EARLY NEXT WK...THEN UNCERTAINTY DEVELOPS AS PATTERN BECMG MORE ACTIVE. SFC HIGH PRES WL RESULT IN MAINLY CLR SKIES AND DRY CONDITIONS FOR SUNDAY/MONDAY. GIVEN DEEP DRY AIRMASS ACRS THE NE CONUS...EXPECT LARGE SWINGS IN DIURNAL TEMPS FROM LOWS SAT NIGHT/SUNDAY NIGHT TO HIGHS ON SUNDAY/MONDAY. TEMPS WL BE 4 TO 8 DEGREES BLW NORMAL. THE 00Z ECMWF HAS TRENDED TWD THE GFS/GFS ENSEMBLE AND GEM FOR TUESDAY...WITH TRACK WELL TO OUR SOUTH AND EAST. GIVEN UNCERTAINTY WITH ANTICYCLONIC FLW AROUND HIGH PRES AND POTENTIAL FOR SOME MOISTURE TO ADVECT BACK INTO OUR CENTRAL/EASTERN CWA WL MENTION SCHC/LOW CHC POPS. ALSO...THIS WL CONT WITH PREVIOUS FCSTER THINKING. OTHERWISE...MODELS ARE IN RELATIVELY GOOD AGREEMENT WITH NEXT LARGE SCALE SYNOPTIC SYSTEM IMPACTING OUR REGION LATE WEDS INTO THURS. ONCE AGAIN SFC LOW PRES WL TRACK TO OUR WEST...PLACING OUR CWA IN THE WARM SECTOR BY WEDS ALONG CHCS FOR PRECIP WED AFTN INTO THURS. TEMPS WL BE NEAR NORMAL TUES AND ABOVE NORMAL FOR WEDS INTO THURS. && .AVIATION /12Z THURSDAY THROUGH MONDAY/... THROUGH 12Z FRIDAY...DEVELOPING STRONG SOUTHERLY SFC WINDS WILL CREATE AREAS OF MODERATE TURBULENCE AND AREAS OF POTENTIAL LLVL WIND SHEAR TODAY. AVIATION CHALLENGE THRU THIS EVENING WL BE PLACEMENT OF LIGHT RAIN SHOWERS THIS MORNING...FOLLOWED BY GUSTY WINDS. CRNT SFC ANALYSIS SHOWS HIGH PRES LOCATED OVER NORTHERN NEW ENGLAND WITH A SFC WARM FRNT LIFTING ACRS NORTHERN NY ATTM. THIS FRNT AND ASSOCIATED RIBBON OF DEEPER MOISTURE WL LIFT ACRS NORTHERN NY TAF SITES BTWN 12Z AND 15Z THIS MORNING. BASED OFF THE RAP 13 HAVE TEMPO A PERIOD OF -SHRA FOR MSS/SLK EARLY THIS MORNING. WL USE VCSH AT PBG/BTV BTWN 13-16Z. IN ADDITION...SFC GRADIENT WL INCREASE WITH GUSTY SOUTH WINDS ANTICIPATED. SOUNDINGS SHOW WIND GUSTS POTENTIAL BTWN 25 AND 30 KNTS THIS AFTN...AS SFC HEATING OCCURS. RAP SOUNDINGS SHOW GUST POTENTIAL BTWN 35 ADN 40 KNTS AT MSS/BTV/SLK BTWN 19Z AND 02Z TODAY. VFR CONDITIONS WL PREVAIL THRU TODAY. NAM AND RAP CONTS TO SHOW SOME LLVL RH/CLOUDS INCREASING THIS EVENING WITH THE POTENTIAL FOR SOME MVFR CIGS IN A STRATO CUMULUS DECK...NOT ANTICIPATING FOG/BR GIVEN LLVL WIND PROFILES...WL USE SCATTERED 1200 TO 1500 FT TO SHOW THIS POTENTIAL OUTLOOK 12Z FRIDAY THROUGH MONDAY... GUSTY SOUTHERLY WINDS WL CONT ON FRIDAY AS SFC LOW PRES TRACKS FROM THE GREAT LAKES INTO CENTRAL CANADA. A BROKEN LINE OF SHOWERS WL IMPACT OUR TAF SITES LATE FRIDAY INTO SATURDAY WITH A BRIEF PERIOD OF MVFR CONDITIONS POSSIBLE IN THE HEAVIER SHOWERS. OTHERWISE...SFC HIGH PRES AND VFR CONDITIONS PREVAIL SAT THRU EARLY NEXT WEEK. && .HYDROLOGY... AS OF 451 AM EDT THURSDAY...WARMER TEMPERATURES TODAY AND FRIDAY WILL RESULT IN MELTING SNOW ACROSS THE HIGHER ELEVATIONS OF THE ADIRONDACKS AND GREEN MOUNTAINS. RUNOFF FROM THIS SNOW MELT WILL LEAD TO SOME SHARP RISES ON AREA RIVERS TODAY THROUGH FRIDAY. HOWEVER...NO FLOODING IS EXPECTED AT THIS TIME. && .BTV WATCHES/WARNINGS/ADVISORIES... VT...NONE. NY...NONE. && $$ SYNOPSIS...WGH NEAR TERM...WGH SHORT TERM...WGH LONG TERM...TABER AVIATION...TABER HYDROLOGY...
AREA FORECAST DISCUSSION
NWS BINGHAMTON NY
415 AM EDT THU APR 18 2013 .SYNOPSIS... A WARM FRONT WILL MOVE THROUGH THE REGION TODAY...BRINGING MILDER TEMPERATURES THROUGH FRIDAY. A STRONG COLD FRONT IS EXPECTED TO CROSS THE AREA FRIDAY EVENING ACCOMPANIED BY SHOWERS...AND A CHANCE OF THUNDERSTORMS. COOLER TEMPERATURES WILL FOLLOW AGAIN THIS WEEKEND UNDER FAIR SKIES. && .NEAR TERM /THROUGH 6 PM TODAY/... SHORT TERM GUIDANCE FROM THE NAM/GFS/WRF AND RAP MODELS ARE IN GOOD AGREEMENT TODAY...AND SUGGEST A MILD SURGE OF AIR OVERSPREADING THE REGION ASSOCIATED WITH A WARM FRONTAL PASSAGE ALOFT. LOW LEVEL MOISTURE NOTED WITHIN A MARINE LAYER EXTENDING NORTHWARD FROM THE MID-ATLANTIC STATES WILL MARR THE MILD FORECAST WITH AN ABUNDANCE OF CLOUDS TODAY. PREVIOUS FORECAST INCLUDED PATCHY DRIZZLE...HOWEVER THE ISENTROPIC LIFT ASSOCIATED WITH THE WARM FRONTAL BOUNDARY LOOKS TO BE FOCUSED WELL TO OUR NORTH ALONG THE 850 MB FRONTAL ZONE. THIS LEAVES MAINLY OROGRAPHIC EFFECTS TO SQUEEZE OUT ANY LIGHT PRECIP. THIS IS NOT TYPICALLY FAVORABLE DURING THE WELL MIXED DAYLIGHT HOURS...AND WE EXPECT CLOUD CEILINGS TO BE MODESTLY HIGH TODAY AND NOT CONDUCIVE TO DRIZZLE. DECIDED TO REMOVE MENTION OF PTCHY DRIZZLE FOR TODAY. && .SHORT TERM /6 PM TONIGHT THROUGH SATURDAY NIGHT/... THE SOUTH-SOUTHEASTERLY FLOW IMPINGING ON OUR HIGHER TERRAIN TONIGHT...ALONG WITH BOUNDARY LAYER COOLING AND SATURATION SEEMS TO OFFER THE BETTER OPPORTUNITY FOR DRIZZLE AFTER DARK. WILL KEEP THAT IN THE FORECAST ACROSS THE SOUTHERN TIER NY AND NEPA...AND REFINE THE FORECAST TO FEATURE DRIZZLE MAINLY OVER THE ELEVATIONS ABOVE 1200-1500 FEET. THE MORE INTERESTING PART OF THE FORECAST OCCURS LATER FRIDAY AFTERNOON AS THE MAIN COLD FRONT OF THE APPROACHING STORM SYSTEM CROSSES THE REGION. MODEL SOLUTIONS ARE CONSISTENT AND MAINTAIN THAT THE BULK OF RAIN ACTIVITY WILL BE BETWEEN ABOUT 21Z AND 02Z. FORECAST WIND PROFILES ARE IMPRESSIVE BOTH IN SPEED AND DIRECTIONAL SHEAR...BUT INSTABILITY IS WEAK WITHIN A MODERATELY MOIST ADIABATIC ENVIRONMENT. A FEW HUNDRED J/KG OF CAPE IS ENOUGH TO WARRANT MENTION OF THUNDER...BUT A SVR THREAT AT THIS TIME SEEMS LOW WITH THE EXPECTATION OF AN ABUNDANCE OF LOW CLOUD COVER LIMITING THE DIURNAL HEATING. THE SPC INDICATES GENERAL THUNDER FOR THE REGION BUT NO MENTION OF SVR. GRADIENT SYNOPTIC WINDS DO LOOK BLUSTERY IN THE 15-30 MPH RANGE...BUT AT THIS TIME SHOULD REMAIN SAFELY UNDER ANY KIND OF IMPACT THRESHOLDS. FRONTAL PASSAGE FRIDAY EVENING WILL USHER A GOOD SHOT OF RAIN AND THEN SOME MARKEDLY COLDER AIR HEADING INTO THE WEEKEND WITH OVERNIGHT TEMPS IN THE 30S AND A REBOUND ON SATURDAY ONLY INTO THE 40S. AM NOT TOO EXCITED ABOUT ANY LAKE RESPONSE...HOWEVER COLD ADVECTION CLOUDINESS IS EXPECTED INTO SATURDAY MORNING DESPITE SOME PRONOUNCED DRYING IN THE 1000-500 MB MEAN RH LAYER DEPICTED BY THE MODELS. HIGH PRESSURE BUILDS IN QUICKLY FOR SATURDAY WITH IMPROVING CONDITIONS AND EVENTUALLY CLEARING SKIES HEADING INTO SATURDAY NIGHT. && .LONG TERM /SUNDAY THROUGH WEDNESDAY/... 300 AM UPDATE...LATEST GFS/ECMWF, SHOWS THE ECMWF IN BETTER AGREEMENT WITH THE GFS, INDICATING A WEAKER AND FARTHER OUT TO SEA SFC LOW ALONG THE EAST COAST TUE/WED. CURRENT EXTENDED IN GOOD SHAPE, WILL CONTINUE WITH CHC/SLIGHT CHC POPS TUE THROUGH WEDNESDAY. PREVIOUS DISC... A FAIRLY QUIET PERIOD SHAPING UP FOR THE FIRST HALF OF THE EXTENDED PERIOD AS HIGH PRESSURE QUICKLY BUILDS IN FOLLOWING THE EARLY WEEKEND COLD FRONT. WITH ITS ARRIVAL...COOLER AIR WILL BE IN STORE WITH HIGHS ONLY EXPECTED TO WARM INTO THE UPPER 40S TO LOWER 50S ON SUNDAY. NEXT WX FEATURE OF INTEREST WILL BE A NORTHWARD LIFTING AREA OF LOW PRESSURE ALONG THE EASTERN SEABOARD WHICH THE ECMWF SHOWS MOVING INTO THE AREA SOMETIME DURING THE DAY ON TUESDAY. THE GFS ON THE OTHER HAND KEEPS THIS FEATURE WELL OFFSHORE WITH LITTLE TO NO IMPACT ON OUR AREA. FOR NOW...WILL MAINTAIN SLGT CHC TO CHC MENTION FOR OUR FCST AREA BEGINNING TUE WITH THIS TREND CONTINUING THROUGH THE CONCLUSION OF THE PERIOD AS BOTH THE GFS AND ECMWF SHOW THE NEXT WX SYSTEM/COLD FRONT APPROACHING FROM THE WEST BY MIDWEEK. NO SIGNIFICANT DEVIATIONS FROM HPC GUIDANCE. && .AVIATION /07Z THURSDAY THROUGH MONDAY/... A SFC WARM FRONT SOUTH OF THE REGION WILL LIFT NORTH THROUGH THE AREA LATER TODAY AND THIS EVENING. MOISTURE FROM THIS BOUNDARY AND INCREASING SOUTHEAST FLOW WILL LOWER CIGS TO AROUND 4K FT BETWEEN 09Z-14Z THIS MORNING. CIGS WILL REMAIN AROUND THIS HEIGHT THROUGH THE DAY. THIS EVENING CIGS AT KAVP/KELM/KBGM/KITH WILL LIKELY LOWER INTO THE MVFR CATEGORY. LIGHT DRIZZLE IS ALSO POSSIBLE OVERNIGHT BUT NOT INCLUDED YET AS IT IS MORE LIKELY AFTER 06Z. E/SE WINDS AROUND 10 KNOTS BECOMING S/SE LATER THIS MORNING AT 12-18 KNOTS WITH GUSTS AROUND 25 KNOTS. S/SE WINDS OVERNIGHT AT 10-15 KNOTS. .OUTLOOK... FRI/FRI NGT...MVFR RESTRICTIONS POSSIBLE BY AFTERNOON IN SHRA- TSRA. SAT THROUGH MON...VFR UNDER HIGH PRESSURE. && .BGM WATCHES/WARNINGS/ADVISORIES... PA...NONE. NY...NONE. && $$ SYNOPSIS...JAB NEAR TERM...JAB SHORT TERM...JAB LONG TERM...CMG/RRM AVIATION...RRM
AREA FORECAST DISCUSSION
NWS RALEIGH NC
945 AM EDT THU APR 18 2013 .SYNOPSIS... HIGH PRESSURE CENTERED OFF THE NEW ENGLAND COAST WILL EXTEND DOWN THE EAST COAST TODAY. A STRONG COLD FRONT WILL APPROACH FROM THE WEST TONIGHT... AND CROSS THE REGION FRIDAY AFTERNOON THROUGH FRIDAY NIGHT. COOL HIGH PRESSURE WILL BUILD IN FROM THE WEST ON SATURDAY. && .NEAR TERM /THROUGH TONIGHT/... AS OF 945 AM THURSDAY... TODAY: A WEAKENING MID-LEVEL SHORTWAVE UNDER THE WEST SIDE OF THE BROAD UPPER RIDGE WILL CONTINUE TO LIFT NORTHEAST TODAY. AS OF MID MORNING CENTRAL NORTH CAROLINA WAS UNDER A SURFACE THETA-E MINIMUM...AND WHILE THE 12Z KGSO SOUNDING SHOWED A VERY MOIST LAYER BETWEEN ABOUT 900MB AND 650MB WITH THE LAPSE RATE GREATER THAN MOIST ADIABATIC... DURING THE DAY BOTH THE GFS AND THE NAM FORECAST WARMING AND DRYING IN THAT LAYER. THIS SHOULD BE ENOUGH TO CAP THE ATMOSPHERE TO DEEP CONVECTION. THE RUC...GFS...AND THE NAM ALL SHOW NO QPF IN CENTRAL NORTH CAROLINA THIS AFTERNOON...AND THE HRRR WRF...ASIDE FROM WHAT APPEAR TO BE SOME SPOTTY CU...SEEMS ALSO TO BE VERY LIMITED WITH DEEP CONVECTION. WILL KEEP CHANCES FOR PRECIPITATION BELOW SLIGHT CHANCE THROUGH THE AFTERNOON...AND WITH THE SHORTWAVE THERE WILL BE AREAS OF CLOUDS THAT SHOULD GRADUALLY MIX AND BECOME INCREASINGLY SCATTERED WITH TIME. UNDER AN OVERALL PARTLY SUNNY SKY...1000-850MB THICKNESSES SUPPORT MAXES FROM AROUND 80 TO THE LOWER 80S...IN CONCERT WITH MOS GUIDANCE. MIXING SHOULD PROVIDE FOR SOME WIND GUSTS IN THE UPPER TEENS KNOTS AND A FEW LOWER 20S KNOTS AT TIMES PARTICULARLY FROM AROUND NOON THROUGH THE MIDDLE OF THE AFTERNOON. -DJF TONIGHT: STRENGTHENING SOUTHERLY MOISTURE TRANSPORT WITH THE APPROACH OF THE AMPLIFIED UPPER TROUGH AND ATTENDANT SURFACE COLD FRONT INTO THE TN VALLEY WILL LIKELY SUPPORT WIDESPREAD LOW CLOUDS INTO THE AREA AFTER MIDNIGHT WITH SPOTTY WAA SHOWERS OVERSPREADING THE AREA FROM OFF THE ATLANTIC/SOUTHEAST COAST. LOWS IN THE LOWER 60S. -CBL && .SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/... AS OF 250 AM THURSDAY... A DEAMPLIFYING UPPER TROUGH WILL CONTINUE TO MOVE EAST THROUGHOUT THE DAY ON FRIDAY...WITH THE PARENT SURFACE LOW MOVING WELL NORTH OF THE AREA ACROSS THE GREAT LAKES/CANADA. THE TRAILING COLD FRONT WILL CROSS OUR AREA FRIDAY/FRIDAY NIGHT WITH AN ACCOMPANYING LINE OF SHOWERS AND THUNDERSTORMS. WITH THE BEST FORCING MOVING NORTH OF THE REGION...THE MAIN CONCERN CONTINUES TO BE THE POTENTIAL FOR SEVERE WEATHER. MODELS ARE IN GOOD AGREEMENT WITH THE LINE OF SHOWERS AND THUNDERSTORMS MOVING ACROSS CENTRAL NC FROM WEST TO EAST FRIDAY AFTERNOON THROUGH EARLY SATURDAY MORNING. AS IS COMMONLY THE CASE...PLENTY OF SHEAR WILL BE IN PLACE...AS WELL AS DECENT LOW LEVEL LAPSE RATES AS TEMPS ARE EXPECTED TO RISE INTO THE UPPER 70S/LOWER 80S...BUT THE AMOUNT OF INSTABILITY WILL BE THE MAIN LIMITING FACTOR. MODELS CONTINUE TO PROG ONLY MARGINAL INSTABILITY...LIKELY DUE TO THE EXTENSIVE CLOUD COVER EXPECTED AHEAD OF THE APPROACHING FRONT...AS WELL AS THE SOMEWHAT NOCTURNAL TIMING OF THE PRECIP (THIS SECOND POINT WILL MOSTLY COME INTO PLAY FOR THE EASTERN PORTIONS OF THE FORECAST AREA). THE SPC DECIDED NOT TO UPGRADE THE AREA TO A DAY 2 SLIGHT RISK FOR NOW...MAINLY DUE TO POTENTIAL OF LIMITED INSTABILITY... ALTHOUGH THEY POINTED OUT THAT IF ENOUGH DESTABILIZATION DOES OCCUR...A SLIGHT RISK MAY EVENTUALLY BE NEEDED. NEVERTHELESS...WILL CONTINUE TO MENTION THE POSSIBILITY OF STRONG TO SEVERE STORMS...WITH THE PRIMARY THREAT BEING DAMAGING WIND...IN THE HWO. PRECIP IS EXPECTED TO COME TO AN END FROM WEST TO EAST SATURDAY MORNING...WITH HIGH PRESSURE BUILDING IN FOR SATURDAY NIGHT. HIGHS ON FRIDAY ARE EXPECTED TO RANGE FROM THE UPPER 70S ACROSS THE WEST TO LOW/MID 80S FURTHER EAST. OVERNIGHT LOWS ON FRIDAY NIGHT WILL BE DEPENDENT ON THE TIMING OF THE EXITING PRECIP AND COMMENCEMENT OF COLD AIR ADVECTION. AT THIS TIME...IT APPEARS PRECIP SHOULD CLEAR OUT OF AT LEAST THE WESTERN PORTIONS OF THE FORECAST AREA BEFORE DAYBREAK AND THEREFORE AM EXPECTING TEMPS TO RANGE FROM THE UPPER 40S/LOWER 50S ACROSS THE WEST TO MID/UPPER 50S FURTHER EAST. CONDITIONS WILL IMPROVE THROUGHOUT THE DAY ON SATURDAY AND WITH COLD AIR ADVECTION PERSISTING...HIGHS SHOULD GENERALLY BE IN THE MID/UPPER 60S. OVERNIGHT LOWS ARE EXPECTED TO FALL INTO THE 40S AREAWIDE SATURDAY NIGHT. && .LONG TERM /SUNDAY THROUGH WEDNESDAY/... AS OF 320 AM THURSDAY... COOL AND DRY CONDITIONS TO CLOSE THE WEEKEND AS A BROAD LONG WAVE TROUGH WILL ENCOMPASS MUCH OF THE CONUS WITH A STRONG MIGRATORY CANADIAN SURFACE HIGH BUILDING OVER THE NE US AND MID-ATLANTIC REGION BEFORE QUICKLY SHIFTING OFF THE NEW ENGLAND COAST. A BIT OF UNCERTAINTY BEGINS TO CREEP INTO THE PICTURE OWING TO NORTHERN STREAM AMPLIFICATION OVER THE ROCKIES AND INTO THE CENTRAL US EARLY NEXT WEEK. IN RESPONSE TO THE DIGGING TROUGH...MODELS SHOW WEAK CYCLOGENESIS ALONG THE STALLED BAROCLINIC FRONTAL ZONE OFF THE SOUTHEAST COAST WITH A POTENTIAL FOR ANOTHER HYBRID CAD EVENT EITHER MONDAY OR TUESDAY PENDING THE EVOLUTION OF THE SYSTEM(STRENGTH AND LOCATION OF THE COASTAL WAVE). THIS SCENARIO WOULD ONLY ENHANCE THE PERIOD OF BELOW NORMAL TEMPERATURES WITH THE POTENTIAL FOR THE RAIN AND ASSOCIATED WET BULB COOLING TO KEEP DAYTIME HIGHS IN THE LOWER 50S IF THE WETTER SOLUTIONS VERIFY. HAVE PLENTY TIME TO SIT AND WAIT FOR MODEL DIFFERENCES TO IRON THEMSELVES OUT BEFORE FORECASTING SUCH A DRASTIC CHANGE...BUT THE POTENTIAL IS DEFINITELY THERE GIVEN SUCH A STRONG 1040MB CANADIAN SURFACE HIGH OFF THE NEW ENGLAND COAST. THE LINGERING WEDGE PATTERN LEFT BEHIND WILL ATTEMPT TO ERODE BEFORE THE AFOREMENTIONED TROUGH AND ATTENDANT SFC COLD FRONT APPROACH THE AREA FROM THE WEST ON WEDNESDAY/THURSDAY BRINGING WIDESPREAD SHOWERS AND POSSIBLY THE THREAT OF STORMS. && .AVIATION /14Z THURSDAY THROUGH MONDAY/... AS OF 945 AM THURSDAY... SOME LOW CLOUDS...MAINLY MVFR...WILL GRADUALLY INCREASE TO VFR CONDITIONS AND A 10 TO 15KT SOUTHERLY BREEZE FOR THE AFTERNOON. WIDESPREAD IFR TO LIFT STRATUS/LOW CLOUDS IS EXPECTED TO DEVELOP LATE TONIGHT/EARLY FRIDAY MORNING IN THE STRENGTHENING SOUTHERLY MOIST ADVECTION AHEAD OF THE APPROACHING COLD FRONT. LOOKING AHEAD: ADVERSE AVIATION CONDITIONS ARE EXPECTED FRIDAY AFTERNOON THROUGH FRIDAY NIGHT AS A LINE OF STRONG TO POSSIBLY SEVERE STORMS CROSS THE AREA. VFR CONDITIONS IN ASSOCIATION WITH COOL DRY HIGH PRESSURE WILL DOMINATE THE WEEKEND. WHILE THERE IS STILL SOME UNCERTAINTY WITH RESPECT TO THE STRENGTH AND PROXIMITY TO THE COAST...A COASTAL TROUGH/LOW COULD BRING RESTRICTIONS IN WIDESPREAD MONDAY-TUESDAY. && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...GIH NEAR TERM...DJF/CBL SHORT TERM...KRR LONG TERM...CBL AVIATION...DJF/CBL
AREA FORECAST DISCUSSION
NWS BISMARCK ND
1255 AM CDT THU APR 18 2013 .UPDATE... ISSUED AT 1255 AM CDT THU APR 18 2013 SNOW BAND CONTINUED ACROSS EASTERN SOUTH DAKOTA INTO SOUTHEASTERN NORTH DAKOTA...WITH REGIONAL RADARS INDICATING DEVELOPMENT IN THE ASHLEY AREA FOR THE PAST COUPLE OF HOURS. VISIBILITIES IN OAKES HAD RANGED FROM 1.75 TO 3 MILES IN LIGHT SNOW FOR THE PAST 3 HOURS. KEPT HIGH POPS FOR EASTERN DICKEY AND LAMOURE COUNTIES AND KEPT THE CHANCE MENTION IN THE WEST NEAR ASHLEY AND EDGELEY AND JAMESTOWN. THIS SURGE OF UPPER LEVEL ENERGY WANES TOWARDS DAYBREAK...BUT MODELS CONTINUE TO SHOW ANOTHER WAVE OF ENERGY MOVING NORTHWARD BETWEEN SUNRISE AND NOON. KEPT CHANCE MENTION THERE FOR THE MORNING...BUT PRECIP SHOULD DISSIPATE/MOVE EAST SLOWLY DURING THE LATE MORNING. GIVEN PROLONGED PERIOD OF LIGHT SNOW THAT WAS IN THE OAKES AP OBSERVATIONS...SEE NO REASON TO CHANGE WHAT APPEARS TO BE A VALID SNOWFALL FORECAST. THUS A 2-4 INCH SNOWFALL IN A 36 HOUR PERIOD IN DICKEY/LAMOURE SHOULD COME TO AN END BY NOON. CURRENT FORECAST ON TRACK. UPDATE ISSUED AT 902 PM CDT WED APR 17 2013 SNOW BAND LINING UP ACROSS THE FAR SOUTHEAST AND FAR SOUTH CENTRAL PORTION OF THE STATE FOR THIS EVENING INTO THE EARLY MORNING. RAISED SNOW TO DEFINITE ACROSS DICKEY...MCINTOSH...AND LAMOURE COUNTIES AS WELL AS SOUTHEAST EMMONS. VISIBILITIES IN SNOW DOWN TO 3/4 MILE FROM PHILLIP TO MOBRIDGE EARLIER THIS EVENING AND THIS BAND WILL MOVE NORTHEAST INTO NORTH DAKOTA. RADARS DO SHOW SOME DECREASE IN COVERAGE/INTENSITY AND THE LATEST RUC IMPLIED THIS SNOW WILL DIMINISH LATER TONIGHT...SO SNOWFALL IN 2 INCH RANGE THERE LOOKS OK. REMAINDER OF STATE LOOKS GOOD. CLOUDS MOVING BACK INTO MINOT...BUT CLEARING NORTHWEST. UPDATE ISSUED AT 646 PM CDT WED APR 17 2013 CLEARING SKIES POKING INTO THE NORTHWEST AND NORTH CENTRAL THIS EVENING. BANDS OF HIGH CLOUDS STRETCH SOUTHWEST THROUGH NORTHEAST AND WILL OVER RUN SOME OF THE CLEARING AREAS SOUTH OF MINOT. ACROSS THE SOUTHEAST...LIGHT SNOW WILL CONTINUE ACROSS DICKEY... LAMOURE AND MCINTOSH COUNTIES THROUGH THIS EVENING. MADE SOME ADJUSTMENTS TO CLOUDS NORTH CENTRAL AND NORTHWEST. && .SHORT TERM...(THIS EVENING THROUGH THURSDAY) ISSUED AT 340 PM CDT WED APR 17 2013 FORECAST HIGHLIGHTS IN THE SHORT TERM PERIOD WILL BE CONTINUING CHANCES FOR LIGHT SNOW ACROSS THE SOUTHERN JAMES RIVER VALLEY NOW THROUGH TONIGHT AND INTO THURSDAY. CURRENTLY...A DYNAMIC UPPER LEVEL LONG WAVE TROUGH WAS OVER THE ROCKIES WITH SOUTHWEST FLOW ALOFT OVER THE NORTHERN PLAINS. MULTIPLE EMBEDDED SHORTWAVES IN THE FLOW WERE MOVING NORTHEAST FROM THE BASE OF THE TROUGH ACROSS THE SOUTHERN ROCKIES INTO THE CENTRAL AND NORTHERN PLAINS. AN UPPER LEVEL JET EXTENDS FROM THE BASE OF THE TROUGH TO CENTRAL SOUTH DAKOTA INTO NORTHERN MINNESOTA...PROVIDING THE FOCUS AREA FOR A PERSISTENT BAND OF LIGHT TO MODERATE SNOW OVER MY SOUTHEAST SINCE EARLIER THIS MORNING TILL NOW. WHILE SOME ACCUMULATIONS ARE OCCURRING...THIS IS MAINLY ON GRASSY AREAS WITH ROAD SURFACES WET THANKS TO ROAD SURFACE TEMPERATURES AT 60F OR HIGHER. DUE IN PART TO OUR RECENT SNOWFALL...HIGH BOUNDARY LAYER MOISTURE REMAINS ACROSS THE LOCAL REGION RESULTING IN A PERSISTENT STRATUS DECK STILL IN PLACE OVER MOST OF WEST AND CENTRAL NORTH DAKOTA. DO NOT SEE THIS DISSIPATING UNTIL MAYBE TOMORROW MORNING/AFTERNOON WHEN A S/WV RIDGE MOVES INTO THE STATE HELPING TO SCOUR OUT THE LOW CLOUDS. WILL CONTINUE WITH THE SPS THROUGH THIS EVENING WITH SOME ADDITIONAL LIGHT ACCUMULATIONS POSSIBLE SOUTHEAST WITH BOTH THE NAM AND RAP BRINGING ANOTHER S/WV NORTHEAST ACROSS PORTIONS OF THE JAMES BASIN THIS EVENING. ALREADY SEE THIS ENHANCED AREA OF PRECIP EAST OF THE BLACK HILLS AND WEST OF PIERRE ADVECTING NORTHEAST. WITH NIGHTFALL...ROAD SURFACE TEMPERATURES...AS THEY DID LAST NIGHT...WILL FALL TO AROUND FREEZING...SO ICY CONDITIONS ARE POSSIBLE AND WILL MENTION THIS WITHIN THE SPS. SNOW CHANCES DECREASE THURSDAY MORNING/AFTERNOON ACROSS THE SOUTHEAST AS THE UPPER JET MIGRATES EAST AND WEAK HIGH PRESSURE BUILDS IN ACROSS CENTRAL NORTH DAKOTA. WITH THE CLOUDS SCOURING OUT AND WITH THE S/WV RIDGE PROVIDING SOME WAA...HAVE FORECAST HIGHS THURSDAY NEAR 40 WEST. 30S CENTRAL AND EAST WITH A MODERATE NORTH FLOW REMAINING IN PLACE ALONG WITH A LONGER DURATION OF CLOUDS. .LONG TERM...(THURSDAY NIGHT THROUGH WEDNESDAY) ISSUED AT 340 PM CDT WED APR 17 2013 NO SIGNIFICANT STORMS IN THE LONG TERM PERIOD...HOWEVER EXPECT AN ACTIVE PERIOD THROUGH SUNDAY AS PERIODIC CHANCES FOR SNOW/SLEET/RAIN OCCURS ACROSS WESTERN AND CENTRAL NORTH DAKOTA. THIS WILL RESULT IN A COUPLE OF INCHES OF MORE SNOW TO ACCUMULATE ESPECIALLY OVER NORTH CENTRAL NORTH DAKOTA THROUGH SUNDAY. H5 PATTERN FOR MID TO LATE NEXT WEEK STILL IN GOOD AGREEMENT WITH ESTABLISHING A H5 RIDGE OVER THE NORTHERN ROCKIES WITH A GRADUAL MODERATING TREND AS DENOTED IN THE H85 TEMPERATURES ACROSS MONTANA INTO WESTERN AND CENTRAL NORTH DAKOTA. BEGINNING THURSDAY NIGHT...A WEAK ALBERTA CLIPPER SYSTEM SLIDES INTO NORTHWEST NORTH DAKOTA THURSDAY NIGHT AND INTO SOUTH CENTRAL NORTH DAKOTA 12Z FRIDAY. SHORT RANGE MODELS SHOW A BAND OF LIGHT SNOW OR POSSIBLY A WINTRY MIX ORIENTED NORTHWEST TO SOUTHEAST WITH UP TO ONE INCH OF SNOW IN NORTH CENTRAL NORTH DAKOTA...FROM BOWBELLS TO STANLEY...EAST TO MINOT AND SHERWOOD. PERHAPS A DUSTING COULD OCCUR ELSEWHERE IN CENTRAL NORTH DAKOTA. LINGERING LIGHT SNOW CONTINUES INTO FRIDAY MORNING WITH THE LOW EXITING FRIDAY AFTERNOON. EXPECT A BRIEF PERIOD OF DRY WEATHER FRIDAY AFTERNOON INTO A PORTION OF FRIDAY NIGHT. FRIDAY NIGHT/SATURDAY/SUNDAY...SURFACE LOW PRESSURE/WARM FRONT IN EASTERN MONTANA WILL PROGRESS EAST...RESULTING IN DECENT ISENTROPIC ASCENT ON THE 285K-295K PRESSURE SURFACES. THIS PRODUCES HIGH CHC/LIKELY POPS BY LATE FRIDAY NIGHT WEST...AND SPREADING INTO CENTRAL NORTH DAKOTA SATURDAY. WARMER TEMPERATURES ALOFT WILL RESULT IN RAIN ACROSS SOUTHWEST NORTH DAKOTA SATURDAY...WITH LIGHT SNOW ELSEWHERE. WIDESPREAD SNOWFALL ACCUMULATIONS OF UP TO ONE INCH WILL BE COMMON...WITH A COUPLE OF INCHES FAVORING NORTH CENTRAL NORTH DAKOTA. ABOVE FREEZING ROAD TEMPERATURES DURING THE DAYLIGHT HOURS SHOULD ALLOW FOR MELTING...WITH SNOWFALL ACCUMULATIONS MAINLY ON THE GRASSY AREAS. FOR MONDAY...A NORTHERN STREAM UPPER LOW/TROUGH FOLLOWS...AND DIGS INTO WESTERN NORTH DAKOTA WITH A PRECIPITATION THREAT REMAINING WEST...SOUTH...AND EAST OF THE FORECAST AREA. THIS LOW EJECTS OUT LATE TUESDAY WITH A BUILDING H5 RIDGE DEVELOPING ALONG THE WEST COAST. THIS RIDGE SLOWLY SIDES EAST INTO THE NORTHERN ROCKIES WEDNESDAY THROUGH FRIDAY WITH A GRADUAL WARMUP. ABOVE AVERAGE TEMPERATURES LIKELY IN THE WEST BY LATE NEXT WEEK. THIS SHOULD ALSO PROMOTE A GENTLE MELT OF THE SNOWPACK UNDER A DRY WEATHER REGIME. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT) ISSUED AT 1255 AM CDT THU APR 18 2013 PLENTY OF LOW LEVEL MOISTURE FROM MELTING SNOW...AS WELL AS FROM THE WRAP AROUND MOISTURE ASSOCIATED WITH THE LARGE STORM SYSTEM AFFECTING THE PLAINS TO THE GREAT LAKES. EXPECT VFR TO BECOME MVFR DURING THE NIGHTTIME HOURS...AS EXPECT FOG DEVELOPMENT IN THE CLEARING AREA IN THE NORTHWEST PART OF THE STATE AND THE ASSOCIATED LOW LEVEL MOISTURE FROM THE STORM SYSTEM MOVING INTO THE STATE FROM THE SOUTHEAST. EXPECT VFR CONDITIONS TO RETURN TO TAF SITES FROM 16Z-21Z. && .BIS WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...JV SHORT TERM...NH LONG TERM...KS AVIATION...JV
AREA FORECAST DISCUSSION
NWS WILMINGTON OH
627 AM EDT THU APR 18 2013 .SYNOPSIS... AN ENERGETIC LOW PRESSURE SYSTEM WILL MOVE NORTHEAST THROUGH THE MID MISSISSIPPI VALLEY TODAY...LIFTING A WARM FRONT NORTH OF THE REGION...AND ALLOWING FOR VERY WARM CONDITIONS ACROSS THE OHIO VALLEY. AS THE LOW ENTERS THE GREAT LAKES EARLY FRIDAY...THE TRAILING COLD FRONT WILL SWING THROUGH WITH A LINE OF PRECIPITATION AND GUSTY WINDS. HIGH PRESSURE WILL SETTLE INTO THE OHIO VALLEY FOR THE WEEKEND...BRINGING MUCH COOLER BUT DRY WEATHER. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... DEVELOPING SURFACE LOW PRESSURE IS CURRENTLY LOCATED OVER MISSOURI...AND WILL BEGIN A NORTHEASTWARD TREK TOWARD THE SOUTHERN GREAT LAKES REGION TODAY. AS AN IMPRESSIVE FEED OF MOISTURE SETS UP ACROSS THE MISSISSIPPI VALLEY...AND THE SURFACE LOW SPLITS INTO TWO AND REFOCUSES NEAR CHICAGO BY EVENING...THE ILN CWA WILL BE FAR ENOUGH FROM THE ACTION TO PROVIDE A MOSTLY DRY FORECAST. THE CWA WILL BE FIRMLY IN THE WARM SECTOR OF THIS WEATHER SYSTEM...WITH STRONG SSW FLOW PROVIDING WARM ADVECTION AT ALL LEVELS. BETWEEN THE WARM AIR MOVING IN ALOFT...AND THE DISTANCE FROM THE SURFACE BOUNDARIES...DEVELOPMENTAL CONVECTION OVER THE ILN CWA APPEARS UNLIKELY. A MAJORITY OF THE MODELS DO ALLOW FOR SOME WEAK DEVELOPMENT ACROSS EASTERN OHIO...WHERE SURFACE T/TD WILL BE A BIT HIGHER...PERHAPS JUST ENOUGH TO WEAKLY BREAK THE CAP WITH DISORGANIZED CONVECTION. VERY LITTLE JUSTIFICATION FOR MORE THAN 20-POPS IN CENTRAL OHIO BECAUSE OF THIS...GIVEN AN ALMOST COMPLETE LACK OF SUPPORT FOR ORGANIZED LIFT. OF GREATER CONCERN IS AN INDICATION FROM RECENT HRRR RUNS / THE 06Z NAM12 / THE 00Z SPC-WRF...WHICH DEPICT A PROGRESSIVE MCS MOVING OUT OF MISSOURI/ILLINOIS THIS MORNING AND HEADING ENE INTO THE NW ILN CWA BY AFTERNOON. THIS SCENARIO IS NOT SUPPORTED BY THE ENTIRE MODEL SUITE...AND IN FACT...WAS A LATE ADDITION EVEN TO THIS DISCUSSION. ALTHOUGH THE WIND FLOW BELOW 500MB IS GENERALLY SOUTH-SOUTHWESTERLY...WHICH WOULD NOT SUPPORT SUCH A MOTION...THIS MAY BE A SITUATION WHERE CONVECTION DEVELOPS AND PROPAGATES TOWARD INSTABILITY ALONG THE NORTHERN GRADIENT. INSTABILITY WILL CERTAINLY BUILD OVER INDIANA AND OHIO BY AFTERNOON...MEANING THAT THIS SCENARIO WILL HAVE TO BE MONITORED CLOSELY. ANOTHER ISSUE FOR TODAY IS SIMPLY THE STRENGTH OF THE SSW FLOW...WHICH WILL BE REALIZED A BIT AT THE SURFACE THANKS TO FAVORABLE MIXING (AT OR ABOVE 850MB). THERE IS WIDESPREAD MODEL AGREEMENT IN 850MB WINDS EXCEEDING 40 KNOTS THIS AFTERNOON IN THE NORTHWESTERN PORTION OF THE CWA...WITH VALUES NEAR 30 KNOTS ALL THE WAY TO THE SOUTHEASTERN CWA. THIS IS IN RESPONSE TO THE DEEPENING SURFACE/850MB LOW TO THE NORTHWEST...WHICH ALLOWS FOR A PRESSURE GRADIENT THAT ONLY GETS PROGRESSIVELY MORE TIGHT THROUGH THE DAY. USING BUFKIT MIXING AS A GUIDE...GUSTS SHOULD EASILY REACH 25-30 KNOTS IN THE SOUTHEASTERN CWA...WITH 30-35 KNOT VALUES NEAR AND NORTH/WEST OF THE INTERSTATE 71 CORRIDOR. THERE WAS SOME DISCUSSION ON THE POSSIBILITY OF ADVISORY-CRITERIA CONDITIONS IN THE WESTERN HALF OF THE CWA. THIS LOOKS UNLIKELY TO OCCUR IN THE CINCINNATI AREA...BUT FOR DAYTON/RICHMOND ON NORTH...IT WOULD NOT BE SURPRISING TO SEE A FEW GUSTS IN THE 35-40 KNOT RANGE. NOT QUITE ENOUGH FOR A HEADLINE...BUT EASILY WORTH SPS/HWO MENTIONS. MAX TEMPS WILL BE HIGHEST IN THE SOUTHEAST...WHERE CLOUDS WILL BE LESS OF AN IMPACT...AND THE MAGNITUDE OF THE ADVECTION IS A LITTLE STRONGER. 80S ARE IN THE GRIDS FOR MOST OF THE CWA (MID-80S IN THE SOUTHEAST)...ROUGHLY 15 DEGREES ABOVE NORMAL. RECORD HIGHS AT THE BIG THREE (87 CVG / 88 CMH / 89 DAY) ARE LIKELY SAFE FROM THE FORECAST VALUES TODAY (83 CVG / 82 CMH / 81 DAY). && .SHORT TERM /6 PM THIS EVENING THROUGH SATURDAY NIGHT/... THE OVERALL LARGE-SCALE MODEL AGREEMENT FOR THE IMPENDING COLD FRONTAL PASSAGE REMAINS VERY STRONG. AS THIS SYSTEM IS NOW IN THE RANGE OF SEVERAL MESOSCALE MODEL RUNS...THE FINER DETAILS THAT ARE NOW BEING RESOLVED RAISE SEVERAL QUESTIONS INTO THE OTHERWISE WELL-HANDLED FORECAST. AN AREA OF LOW PRESSURE (THE SOUTHWESTERN OF THE TWO FROM THE SPLIT) WILL BE LOCATED NEAR CHICAGO AT 00Z...MOVING NORTHEAST TOWARD THE STRAITS OF MACKINAC BY 12Z FRIDAY MORNING. A STRONG COLD FRONT IS EASILY EVIDENT ON JUST ABOUT ANY MODEL FIELD OF CHOICE (MSLP...THETA-E...SURFACE-BASED LI...WINDS...ET CETERA). A DEEPENING UPPER TROUGH WILL BE MOVING ENE THROUGH THE NORTHERN MISSISSIPPI VALLEY...WITH AN ALREADY TIGHT HEIGHT PATTERN BECOMING EVEN MORE SO BY FRIDAY MORNING. THIS DYNAMIC SETUP WILL ALLOW FOR A LARGE AMOUNT OF WIND ENERGY TO BE PRESENT OVER THE OHIO VALLEY...LEADING THE PRIMARY SEVERE QUESTION INTO THAT OF INSTABILITY AND TIMING. AS MENTIONED IN THE NEAR TERM...A FEW MODELS INDICATE ACTIVITY SNEAKING INTO THE CWA WELL AHEAD OF THE FRONTAL PASSAGE. RAP13/NAM12 DATA SEEMS TO DEVELOP QUITE A BIT OF CONVECTION AHEAD OF THE SHARP FRONTAL BOUNDARY...GENERALLY OVER INDIANA BUT ALSO A BIT INTO OHIO. ON THE HIGH-RESOLUTION RUNS...SIMULATED REFLECTIVITY INDICATES CONVECTIVE ELEMENTS (BOWS AND LINE SEGMENTS) THAT ATTAIN A BIT MORE OF A SW-TO-NE DIRECTION OF MOVEMENT (AS OPPOSED TO THE LARGE-SCALE FLOW THROUGH THE FRONTAL REGION...WHICH IS SSW-TO-NNE). THIS IS IN CONTRAST TO SOME OTHER MODELS (SUCH AS THE CMC REGIONAL / ECMWF) WHICH KEEP PRECIPITATION LIMITED VERY STRICTLY TO THE FRONTAL BOUNDARY AND BEHIND. EVEN IF CONVECTION DOES NOT OCCUR AHEAD OF THE FRONT...ONE KEY THAT CAN BE PICKED UP FROM THESE HIGHER-RESOLUTION RUNS IS THAT THE NATURE OF THE FRONT EDGE OF THE CONVECTION WILL NOT LIKELY BE AS ONE STRAIGHT LINE. RATHER...THE STRUCTURE MAY BE MORE COMPLICATED...AND ANALYSIS OF THE MESOSCALE PARAMETERS DOES SUPPORT A QLCS SCENARIO WITH EMBEDDED WAVES IN THE PATTERN. AS IS OFTEN THE CASE IN THESE SCENARIOS...THE 0-6KM SHEAR IS STRONG (50-60 KNOTS) BUT IT IS THE 0-1KM SHEAR THAT REALLY STICKS OUT AS IMPRESSIVE (ALSO 40-50 KNOTS). HODOGRAPHS IN THIS LAYER SHOW A NICE CURVE FROM SOUTHERLY TO UP TO 60 KNOTS OF SOUTHWESTERLY FLOW AT ABOUT 3000 FEET AGL. THE OBVIOUS TAKEAWAY FROM THESE PARAMETERS IS THAT THEY ARE QUITE FAVORABLE FOR STRONG WINDS AND EVEN TORNADO DEVELOPMENT. HOWEVER...THE BOUNDARY LAYER INSTABILITY WILL BE THE QUESTION AS FOR WHETHER OR NOT THIS KINETIC ENERGY CAN BE REALIZED. FEW MODELS (IF ANY) SHOW MORE THAN A COUPLE HUNDRED J/KG OF LEGITIMATE SURFACE BASED CAPE BY THE TIME THE FRONT IS ENTERING THE ILN CWA...AND EVEN THIS DISSIPATES WITH TIME AS THE FRONT CROSSES WEST TO EAST. HOWEVER...AT THE TIME OF THE ARRIVAL OF THE FRONT...MODEL SOUNDINGS INDICATE A THERMAL PROFILE THAT IS ROUGHLY MOIST ADIABATIC. THERE ARE NO SIGNS OF A LEGITIMATE TEMPERATURE INVERSION DEVELOPING BEFORE THE FRONT ARRIVES. SPC HAS ISSUED A RELATIVELY LARGE MODERATE RISK TODAY...EXTENDING FROM MICHIGAN TO MISSISSIPPI. THIS AREA CAPTURES THE LOCATION OF THE FRONT AND ITS CONVECTION AT A MORE FAVORABLE DIURNAL TIME PERIOD. WHILE THIS IS CLEARLY THE AREA MORE FAVORED FOR A SIGNIFICANT SEVERE THREAT...THE THREAT IS EXPECTED TO CONTINUE INTO THE ILN CWA AS THE FRONT ARRIVES NEAR MIDNIGHT. THOUGH THE GRADUAL TREND WILL BE TOWARD A WEAKENING SYSTEM (WITH THUNDER BECOMING QUESTIONABLE LATER IN THE OVERNIGHT)...THE ELEMENTS APPEAR TO BE IN PLACE FOR A QLCS CAPABLE OF DAMAGING WIND AND MESOVORTICIES. THESE SEVERE WEATHER THREATS WILL BE GREATEST IN THE WESTERN HALF OF THE CWA...WHERE THE SPC SLIGHT RISK IS INDICATED...BUT MAY BE PRESENT EVEN THROUGH THE EAST. IN TERMS OF THE OTHER ELEMENTS OF THE FORECAST... POPS...AN ATTEMPT WAS MADE TO TIME OUT THE FRONT WITH AN AREA OF 100-POPS...AND KEEP THE GRADIENTS AS SHARP AS POSSIBLE ON EITHER SIDE. HOWEVER...SOME POPS HAD TO BE INCLUDED AHEAD OF THE FRONT TO ACCOUNT FOR A POSSIBILITY OF PROGRESSIVE ELEMENTS OR WARM SECTOR CONVECTION (THOUGH ADMITTEDLY...THE LATTER WILL BECOME RATHER UNLIKELY AFTER SUNSET). ON FRIDAY...SOME POPS WERE INCLUDED IN THE NORTH AS THE BACK-END OF THE UPPER TROUGH MOVES THROUGH THE GREAT LAKES...BUT THIS IS UNLIKELY TO RESULT IN ANYTHING MORE THAN SOME LIGHT RAIN SHOWERS. TEMPS...NON-DIURNAL THROUGH THURSDAY NIGHT AND FRIDAY...WITH THE FRONTAL PASSAGE ALMOST COMPLETELY DOMINATING THE DIURNAL COMPONENT OF THE TEMPERATURE CURVE. MAX TEMPS FOR FRIDAY WILL BE JUST BEHIND THE FRONT...WITH COLD ADVECTION THROUGH THE DAY KEEPING TEMPS FROM RISING. RAINFALL...A GENERAL MODEL CONSENSUS PROVIDES FOR RAINFALL AMOUNTS OF AROUND AN INCH IN THE WESTERN CWA...AND SLIGHTLY HIGHER THAN A HALF INCH IN THE EASTERN CWA. ALTHOUGH GROUND CONDITIONS ARE A BIT ON THE WET SIDE...THESE VALUES DO NOT SEEM TO BE ENOUGH TO PROMOTE A FLOODING THREAT...ESPECIALLY CONSIDERING THE PROGRESSIVE NATURE OF THIS FRONTAL SYSTEM. OHRFC MMEFS GUIDANCE DOES NOT INDICATE MUCH OF A CHANCE FOR ANY ILN RIVER POINTS TO ENTER FLOOD OR EVEN ACTION STAGE. SOUTH-SOUTHWESTERLY MOISTURE TRANSPORT AHEAD OF THE FRONT IS IMPRESSIVE...AND IT WOULD NOT BE SURPRISING IF A FEW CONVECTIVE ELEMENTS LED TO LOCALIZED HIGHER VALUES THAN THE MENTIONED FORECAST. SO...ISOLATED/LOCALIZED FLOODING COULD BE POSSIBLE...BUT LIKELY ONLY OF THE SHORT-TERM VARIETY. WINDS...ASIDE FROM THE SEVERE THREAT...STRONG WINDS ARE EXPECTED IN THE COLD ADVECTION (WSW FLOW) BEHIND THE COLD FRONT. THIS PATTERN SUPPORTS MIXING AS THE BOUNDARY LAYER COOLS RATHER DEEPLY...AND GUSTS IN THE NORTH MAY APPROACH ADVISORY CRITERIA. FINALLY...THE MUCH COLDER AIR MASS WILL PRESENT THE POSSIBILITY OF FROST ON FRIDAY AND SATURDAY NIGHTS...ESPECIALLY SATURDAY NIGHT (WITH CLEARER SKIES). && .LONG TERM /SUNDAY THROUGH WEDNESDAY/... MODELS ARE IN A WIDE RANGE FOR TIMING FOR THE TUESDAY/WEDNESDAY SYSTEM. THE PREVIOUS FORECAST APPEARS TO HAVE THE BEST INITIAL CONDITIONS BUT SOME NEIGHBORING OFFICES APPEAR HIGHER THAN I AM WILLING TO GO WITH RAIN CHANCES OVERNIGHT TUESDAY. GIVEN THE LATEST EUROPEAN WHICH SPINS THE SYSTEM UP IN THE MIDWEST ON TUESDAY...IT HAS A MUCH SLOWER AND MORE DEVELOPED SYSTEM THAN THE GFS WHICH IS INDICATING AN OPEN WAVE YET STRONG COLD FRONTAL PASSAGE EARLY WEDNESDAY. WPC HAS THIS FRONT ON THE OTHER SIDE OF THE APPALACHIANS AT THIS TIME WHICH APPEARS INCONSISTENT WITH THE REST OF THE GUIDANCE I SEE. UNTIL THE RAIN HITS WITH THE NEXT SYSTEM DAYS 6/7...TEMPERATURES WILL BE ON THE INCREASE AND START FROM A COOLER 50S ON SATURDAY WITH OVERNIGHT LOWS LIKELY NEEDING FROST HEADLINES. BY THIS TIME NEXT WEEK AHEAD OF THE COLD FRONT...70S WILL BE FOUND AGAIN WITH OVERNIGHT LOWS IN THE 50S. HAVE GONE WARMER THAN GUIDANCE AHEAD OF THE NEXT SYSTEM BUT FEEL THAT THE FORECAST WILL CONTINUE TO BE ADJUSTED UPWARD A LITTLE BIT EACH DAY. && .AVIATION /10Z THURSDAY THROUGH MONDAY/... POTENT UPPER LEVEL TROUGH WILL MOVE INTO THE PLAINS TODAY. AS IT DOES...SURFACE LOW PRESSURE WILL DEEPEN OVER THE MID MISSISSIPPI RIVER VALLEY. FOR THE MOST PART...THE AREA SHOULD BE MAINLY WARM SECTORED WITH A CHANCE OF A POP UP SHOWER OR STORM IN THE AFTERNOON. SOME OF THE HIGHER RESOLUTION...CONVECTIVE ALLOWING MODELS...HOWEVER...ARE SUGGESTING THAT SOME CONVECTIVE LINE SEGMENTS MOVING ACROSS ILLINOIS INTO INDIANA THIS MORNING MAY PUSH INTO EAST CENTRAL INDIANA AND WEST CENTRAL OHIO THIS AFTERNOON. THIS WOULD BRING AN INCREASE RISK FOR THUNDERSTORMS AT THE KDAY TAF. HAVE PLACED A VCTS/CB IN KDAY FOR THE AFTERNOON HOURS. RADAR AND MODEL TRENDS WILL HAVE TO BE WATCHED TO SEE IF THIS SCENARIO MATERIALIZES. AS THE SURFACE LOW DEEPENS AND DAYTIME MIXING KICKS IN...SOUTHERLY WINDS WILL INCREASE AND WILL BE GUSTY BETWEEN 30 AND 35 KNOTS. FOR TONIGHT...ANY AFTERNOON CONVECTION LOOKS TO WANE UNTIL A STRONG COLD FRONT ARRIVES BETWEEN 06Z AND 12Z. AS IT DOES...A LINE OF SHOWERS AND EMBEDDED THUNDERSTORMS ARE EXPECTED ALONG THE COLD FRONT...FOLLOWED BY A PERIOD OF MODERATE TO LOCALLY HEAVY RAIN SHOWERS. THIS WILL RESULT IN CONDITIONS DROPPING INTO THE MVFR CATEGORY ALONG WITH SOME IFR VISIBILITIES IN THE HEAVIER RAIN. ALSO...WINDS WILL CONTINUE GUSTY AND SHIFT TO THE WEST WITH FROPA. WINDS WILL BE LOCALLY HIGHER IN AND NEAR THUNDERSTORMS. AT THIS TIME,..IT APPEARS INSTABILITY WILL BE WEAKENING AS THE FRONT PUSHES TOWARD THE KCMH/KLCK TAF SITES TOWARD 12Z BUT HAVE DECIDED TO LEAVE A VCTS IN THESE TERMINALS AS WELL. OUTLOOK...MVFR CONDITIONS WITH LOCAL IFR VISIBILITIES EXPECTED IN SHOWERS FRIDAY MORNING. WEST WINDS GUSTING BETWEEN 30 AND 35 KNOT ON FRIDAY. && .ILN WATCHES/WARNINGS/ADVISORIES... OH...NONE. KY...NONE. IN...NONE. && $$ SYNOPSIS...HATZOS NEAR TERM...HATZOS SHORT TERM...HATZOS LONG TERM...FRANKS AVIATION...HICKMAN
AREA FORECAST DISCUSSION
NWS WILMINGTON OH
450 AM EDT THU APR 18 2013 .SYNOPSIS... AN ENERGETIC LOW PRESSURE SYSTEM WILL MOVE NORTHEAST THROUGH THE MID MISSISSIPPI VALLEY TODAY...LIFTING A WARM FRONT NORTH OF THE REGION...AND ALLOWING FOR VERY WARM CONDITIONS ACROSS THE OHIO VALLEY. AS THE LOW ENTERS THE GREAT LAKES EARLY FRIDAY...THE TRAILING COLD FRONT WILL SWING THROUGH WITH A LINE OF PRECIPITATION AND GUSTY WINDS. HIGH PRESSURE WILL SETTLE INTO THE OHIO VALLEY FOR THE WEEKEND...BRINGING MUCH COOLER BUT DRY WEATHER. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... DEVELOPING SURFACE LOW PRESSURE IS CURRENTLY LOCATED OVER MISSOURI...AND WILL BEGIN A NORTHEASTWARD TREK TOWARD THE SOUTHERN GREAT LAKES REGION TODAY. AS AN IMPRESSIVE FEED OF MOISTURE SETS UP ACROSS THE MISSISSIPPI VALLEY...AND THE SURFACE LOW SPLITS INTO TWO AND REFOCUSES NEAR CHICAGO BY EVENING...THE ILN CWA WILL BE FAR ENOUGH FROM THE ACTION TO PROVIDE A MOSTLY DRY FORECAST. THE CWA WILL BE FIRMLY IN THE WARM SECTOR OF THIS WEATHER SYSTEM...WITH STRONG SSW FLOW PROVIDING WARM ADVECTION AT ALL LEVELS. BETWEEN THE WARM AIR MOVING IN ALOFT...AND THE DISTANCE FROM THE SURFACE BOUNDARIES...DEVELOPMENTAL CONVECTION OVER THE ILN CWA APPEARS UNLIKELY. A MAJORITY OF THE MODELS DO ALLOW FOR SOME WEAK DEVELOPMENT ACROSS EASTERN OHIO...WHERE SURFACE T/TD WILL BE A BIT HIGHER...PERHAPS JUST ENOUGH TO WEAKLY BREAK THE CAP WITH DISORGANIZED CONVECTION. VERY LITTLE JUSTIFICATION FOR MORE THAN 20-POPS IN CENTRAL OHIO BECAUSE OF THIS...GIVEN AN ALMOST COMPLETE LACK OF SUPPORT FOR ORGANIZED LIFT. OF GREATER CONCERN IS AN INDICATION FROM RECENT HRRR RUNS / THE 06Z NAM12 / THE 00Z SPC-WRF...WHICH DEPICT A PROGRESSIVE MCS MOVING OUT OF MISSOURI/ILLINOIS THIS MORNING AND HEADING ENE INTO THE NW ILN CWA BY AFTERNOON. THIS SCENARIO IS NOT SUPPORTED BY THE ENTIRE MODEL SUITE...AND IN FACT...WAS A LATE ADDITION EVEN TO THIS DISCUSSION. ALTHOUGH THE WIND FLOW BELOW 500MB IS GENERALLY SOUTH-SOUTHWESTERLY...WHICH WOULD NOT SUPPORT SUCH A MOTION...THIS MAY BE A SITUATION WHERE CONVECTION DEVELOPS AND PROPAGATES TOWARD INSTABILITY ALONG THE NORTHERN GRADIENT. INSTABILITY WILL CERTAINLY BUILD OVER INDIANA AND OHIO BY AFTERNOON...MEANING THAT THIS SCENARIO WILL HAVE TO BE MONITORED CLOSELY. ANOTHER ISSUE FOR TODAY IS SIMPLY THE STRENGTH OF THE SSW FLOW...WHICH WILL BE REALIZED A BIT AT THE SURFACE THANKS TO FAVORABLE MIXING (AT OR ABOVE 850MB). THERE IS WIDESPREAD MODEL AGREEMENT IN 850MB WINDS EXCEEDING 40 KNOTS THIS AFTERNOON IN THE NORTHWESTERN PORTION OF THE CWA...WITH VALUES NEAR 30 KNOTS ALL THE WAY TO THE SOUTHEASTERN CWA. THIS IS IN RESPONSE TO THE DEEPENING SURFACE/850MB LOW TO THE NORTHWEST...WHICH ALLOWS FOR A PRESSURE GRADIENT THAT ONLY GETS PROGRESSIVELY MORE TIGHT THROUGH THE DAY. USING BUFKIT MIXING AS A GUIDE...GUSTS SHOULD EASILY REACH 25-30 KNOTS IN THE SOUTHEASTERN CWA...WITH 30-35 KNOT VALUES NEAR AND NORTH/WEST OF THE INTERSTATE 71 CORRIDOR. THERE WAS SOME DISCUSSION ON THE POSSIBILITY OF ADVISORY-CRITERIA CONDITIONS IN THE WESTERN HALF OF THE CWA. THIS LOOKS UNLIKELY TO OCCUR IN THE CINCINNATI AREA...BUT FOR DAYTON/RICHMOND ON NORTH...IT WOULD NOT BE SURPRISING TO SEE A FEW GUSTS IN THE 35-40 KNOT RANGE. NOT QUITE ENOUGH FOR A HEADLINE...BUT EASILY WORTH SPS/HWO MENTIONS. MAX TEMPS WILL BE HIGHEST IN THE SOUTHEAST...WHERE CLOUDS WILL BE LESS OF AN IMPACT...AND THE MAGNITUDE OF THE ADVECTION IS A LITTLE STRONGER. 80S ARE IN THE GRIDS FOR MOST OF THE CWA (MID-80S IN THE SOUTHEAST)...ROUGHLY 15 DEGREES ABOVE NORMAL. RECORD HIGHS AT THE BIG THREE (87 CVG / 88 CMH / 89 DAY) ARE LIKELY SAFE FROM THE FORECAST VALUES TODAY (83 CVG / 82 CMH / 81 DAY). && .SHORT TERM /6 PM THIS EVENING THROUGH SATURDAY NIGHT/... THE OVERALL LARGE-SCALE MODEL AGREEMENT FOR THE IMPENDING COLD FRONTAL PASSAGE REMAINS VERY STRONG. AS THIS SYSTEM IS NOW IN THE RANGE OF SEVERAL MESOSCALE MODEL RUNS...THE FINER DETAILS THAT ARE NOW BEING RESOLVED RAISE SEVERAL QUESTIONS INTO THE OTHERWISE WELL-HANDLED FORECAST. AN AREA OF LOW PRESSURE (THE SOUTHWESTERN OF THE TWO FROM THE SPLIT) WILL BE LOCATED NEAR CHICAGO AT 00Z...MOVING NORTHEAST TOWARD THE STRAITS OF MACKINAC BY 12Z FRIDAY MORNING. A STRONG COLD FRONT IS EASILY EVIDENT ON JUST ABOUT ANY MODEL FIELD OF CHOICE (MSLP...THETA-E...SURFACE-BASED LI...WINDS...ET CETERA). A DEEPENING UPPER TROUGH WILL BE MOVING ENE THROUGH THE NORTHERN MISSISSIPPI VALLEY...WITH AN ALREADY TIGHT HEIGHT PATTERN BECOMING EVEN MORE SO BY FRIDAY MORNING. THIS DYNAMIC SETUP WILL ALLOW FOR A LARGE AMOUNT OF WIND ENERGY TO BE PRESENT OVER THE OHIO VALLEY...LEADING THE PRIMARY SEVERE QUESTION INTO THAT OF INSTABILITY AND TIMING. AS MENTIONED IN THE NEAR TERM...A FEW MODELS INDICATE ACTIVITY SNEAKING INTO THE CWA WELL AHEAD OF THE FRONTAL PASSAGE. RAP13/NAM12 DATA SEEMS TO DEVELOP QUITE A BIT OF CONVECTION AHEAD OF THE SHARP FRONTAL BOUNDARY...GENERALLY OVER INDIANA BUT ALSO A BIT INTO OHIO. ON THE HIGH-RESOLUTION RUNS...SIMULATED REFLECTIVITY INDICATES CONVECTIVE ELEMENTS (BOWS AND LINE SEGMENTS) THAT ATTAIN A BIT MORE OF A SW-TO-NE DIRECTION OF MOVEMENT (AS OPPOSED TO THE LARGE-SCALE FLOW THROUGH THE FRONTAL REGION...WHICH IS SSW-TO-NNE). THIS IS IN CONTRAST TO SOME OTHER MODELS (SUCH AS THE CMC REGIONAL / ECMWF) WHICH KEEP PRECIPITATION LIMITED VERY STRICTLY TO THE FRONTAL BOUNDARY AND BEHIND. EVEN IF CONVECTION DOES NOT OCCUR AHEAD OF THE FRONT...ONE KEY THAT CAN BE PICKED UP FROM THESE HIGHER-RESOLUTION RUNS IS THAT THE NATURE OF THE FRONT EDGE OF THE CONVECTION WILL NOT LIKELY BE AS ONE STRAIGHT LINE. RATHER...THE STRUCTURE MAY BE MORE COMPLICATED...AND ANALYSIS OF THE MESOSCALE PARAMETERS DOES SUPPORT A QLCS SCENARIO WITH EMBEDDED WAVES IN THE PATTERN. AS IS OFTEN THE CASE IN THESE SCENARIOS...THE 0-6KM SHEAR IS STRONG (50-60 KNOTS) BUT IT IS THE 0-1KM SHEAR THAT REALLY STICKS OUT AS IMPRESSIVE (ALSO 40-50 KNOTS). HODOGRAPHS IN THIS LAYER SHOW A NICE CURVE FROM SOUTHERLY TO UP TO 60 KNOTS OF SOUTHWESTERLY FLOW AT ABOUT 3000 FEET AGL. THE OBVIOUS TAKEAWAY FROM THESE PARAMETERS IS THAT THEY ARE QUITE FAVORABLE FOR STRONG WINDS AND EVEN TORNADO DEVELOPMENT. HOWEVER...THE BOUNDARY LAYER INSTABILITY WILL BE THE QUESTION AS FOR WHETHER OR NOT THIS KINETIC ENERGY CAN BE REALIZED. FEW MODELS (IF ANY) SHOW MORE THAN A COUPLE HUNDRED J/KG OF LEGITIMATE SURFACE BASED CAPE BY THE TIME THE FRONT IS ENTERING THE ILN CWA...AND EVEN THIS DISSIPATES WITH TIME AS THE FRONT CROSSES WEST TO EAST. HOWEVER...AT THE TIME OF THE ARRIVAL OF THE FRONT...MODEL SOUNDINGS INDICATE A THERMAL PROFILE THAT IS ROUGHLY MOIST ADIABATIC. THERE ARE NO SIGNS OF A LEGITIMATE TEMPERATURE INVERSION DEVELOPING BEFORE THE FRONT ARRIVES. SPC HAS ISSUED A RELATIVELY LARGE MODERATE RISK TODAY...EXTENDING FROM MICHIGAN TO MISSISSIPPI. THIS AREA CAPTURES THE LOCATION OF THE FRONT AND ITS CONVECTION AT A MORE FAVORABLE DIURNAL TIME PERIOD. WHILE THIS IS CLEARLY THE AREA MORE FAVORED FOR A SIGNIFICANT SEVERE THREAT...THE THREAT IS EXPECTED TO CONTINUE INTO THE ILN CWA AS THE FRONT ARRIVES NEAR MIDNIGHT. THOUGH THE GRADUAL TREND WILL BE TOWARD A WEAKENING SYSTEM (WITH THUNDER BECOMING QUESTIONABLE LATER IN THE OVERNIGHT)...THE ELEMENTS APPEAR TO BE IN PLACE FOR A QLCS CAPABLE OF DAMAGING WIND AND MESOVORTICIES. THESE SEVERE WEATHER THREATS WILL BE GREATEST IN THE WESTERN HALF OF THE CWA...WHERE THE SPC SLIGHT RISK IS INDICATED...BUT MAY BE PRESENT EVEN THROUGH THE EAST. IN TERMS OF THE OTHER ELEMENTS OF THE FORECAST... POPS...AN ATTEMPT WAS MADE TO TIME OUT THE FRONT WITH AN AREA OF 100-POPS...AND KEEP THE GRADIENTS AS SHARP AS POSSIBLE ON EITHER SIDE. HOWEVER...SOME POPS HAD TO BE INCLUDED AHEAD OF THE FRONT TO ACCOUNT FOR A POSSIBILITY OF PROGRESSIVE ELEMENTS OR WARM SECTOR CONVECTION (THOUGH ADMITTEDLY...THE LATTER WILL BECOME RATHER UNLIKELY AFTER SUNSET). ON FRIDAY...SOME POPS WERE INCLUDED IN THE NORTH AS THE BACK-END OF THE UPPER TROUGH MOVES THROUGH THE GREAT LAKES...BUT THIS IS UNLIKELY TO RESULT IN ANYTHING MORE THAN SOME LIGHT RAIN SHOWERS. TEMPS...NON-DIURNAL THROUGH THURSDAY NIGHT AND FRIDAY...WITH THE FRONTAL PASSAGE ALMOST COMPLETELY DOMINATING THE DIURNAL COMPONENT OF THE TEMPERATURE CURVE. MAX TEMPS FOR FRIDAY WILL BE JUST BEHIND THE FRONT...WITH COLD ADVECTION THROUGH THE DAY KEEPING TEMPS FROM RISING. RAINFALL...A GENERAL MODEL CONSENSUS PROVIDES FOR RAINFALL AMOUNTS OF AROUND AN INCH IN THE WESTERN CWA...AND SLIGHTLY HIGHER THAN A HALF INCH IN THE EASTERN CWA. ALTHOUGH GROUND CONDITIONS ARE A BIT ON THE WET SIDE...THESE VALUES DO NOT SEEM TO BE ENOUGH TO PROMOTE A FLOODING THREAT...ESPECIALLY CONSIDERING THE PROGRESSIVE NATURE OF THIS FRONTAL SYSTEM. OHRFC MMEFS GUIDANCE DOES NOT INDICATE MUCH OF A CHANCE FOR ANY ILN RIVER POINTS TO ENTER FLOOD OR EVEN ACTION STAGE. SOUTH-SOUTHWESTERLY MOISTURE TRANSPORT AHEAD OF THE FRONT IS IMPRESSIVE...AND IT WOULD NOT BE SURPRISING IF A FEW CONVECTIVE ELEMENTS LED TO LOCALIZED HIGHER VALUES THAN THE MENTIONED FORECAST. SO...ISOLATED/LOCALIZED FLOODING COULD BE POSSIBLE...BUT LIKELY ONLY OF THE SHORT-TERM VARIETY. WINDS...ASIDE FROM THE SEVERE THREAT...STRONG WINDS ARE EXPECTED IN THE COLD ADVECTION (WSW FLOW) BEHIND THE COLD FRONT. THIS PATTERN SUPPORTS MIXING AS THE BOUNDARY LAYER COOLS RATHER DEEPLY...AND GUSTS IN THE NORTH MAY APPROACH ADVISORY CRITERIA. FINALLY...THE MUCH COLDER AIR MASS WILL PRESENT THE POSSIBILITY OF FROST ON FRIDAY AND SATURDAY NIGHTS...ESPECIALLY SATURDAY NIGHT (WITH CLEARER SKIES). && .LONG TERM /SUNDAY THROUGH WEDNESDAY/... MODELS ARE IN A WIDE RANGE FOR TIMING FOR THE TUESDAY/WEDNESDAY SYSTEM. THE PREVIOUS FORECAST APPEARS TO HAVE THE BEST INITIAL CONDITIONS BUT SOME NEIGHBORING OFFICES APPEAR HIGHER THAN I AM WILLING TO GO WITH RAIN CHANCES OVERNIGHT TUESDAY. GIVEN THE LATEST EUROPEAN WHICH SPINS THE SYSTEM UP IN THE MIDWEST ON TUESDAY...IT HAS A MUCH SLOWER AND MORE DEVELOPED SYSTEM THAN THE GFS WHICH IS INDICATING AN OPEN WAVE YET STRONG COLD FRONTAL PASSAGE EARLY WEDNESDAY. WPC HAS THIS FRONT ON THE OTHER SIDE OF THE APPALACHIANS AT THIS TIME WHICH APPEARS INCONSISTENT WITH THE REST OF THE GUIDANCE I SEE. UNTIL THE RAIN HITS WITH THE NEXT SYSTEM DAYS 6/7...TEMPERATURES WILL BE ON THE INCREASE AND START FROM A COOLER 50S ON SATURDAY WITH OVERNIGHT LOWS LIKELY NEEDING FROST HEADLINES. BY THIS TIME NEXT WEEK AHEAD OF THE COLD FRONT...70S WILL BE FOUND AGAIN WITH OVERNIGHT LOWS IN THE 50S. HAVE GONE WARMER THAN GUIDANCE AHEAD OF THE NEXT SYSTEM BUT FEEL THAT THE FORECAST WILL CONTINUE TO BE ADJUSTED UPWARD A LITTLE BIT EACH DAY. && .AVIATION /08Z THURSDAY THROUGH MONDAY/... A WARM FRONT WILL CONTINUE TO MOVE NORTH TOWARD THE GREAT LAKES REGION THIS MORNING. POTENT UPPER LEVEL TROUGH WILL MOVE INTO THE PLAINS TODAY. AS IT DOES...SURFACE LOW PRESSURE WILL DEEPEN AS IT MOVE NE FROM THE SOUTHERN PLAINS TO THE UPPER MISSISSIPPI RIVER VALLEY. OUR AREA WILL BE MAINLY WARM SECTORED TODAY WITH A MIX OF DIURNAL CUMULUS AND HIGH LEVEL CLOUDS. THERE IS STILL A SMALL CHANCE OF A POP UP SHOWER OR STORM IN THE WARM SECTOR...BUT THIS IS NOT HIGH ENOUGH TO MENTION IN THE TAFS. AS THE SURFACE LOW DEEPENS AND DAYTIME MIXING KICKS IN...SOUTHERLY WINDS WILL INCREASE AND WILL BE GUSTY BETWEEN 30 AND 35 KNOTS. FOR TONIGHT...DEEPENING LOW PRESSURE WILL MOVE FROM THE UPPER MISSISSIPPI RIVER VALLEY TO THE U.P. OF MICHIGAN. A DYNAMIC COLD FRONT IS FORECAST TO PUSH EAST INTO THE REGION BETWEEN 06Z AND 12Z. AS IT DOES...A LINE OF SHOWERS AND EMBEDDED THUNDERSTORMS ARE EXPECTED ALONG THE COLD FRONT...FOLLOWED BY A PERIOD OF MODERATE TO LOCALLY HEAVY RAIN SHOWERS. THIS WILL RESULT IN CONDITIONS DROPPING INTO THE MVFR CATEGORY ALONG WITH SOME IFR VISIBILITIES IN THE HEAVIER RAIN. ALSO...WINDS WILL CONTINUE GUSTY AND SHIFT TO THE WEST WITH FROPA. WINDS WILL BE LOCALLY HIGHER IN AND NEAR THUNDERSTORMS. ATTM...IT APPEARS INSTABILITY WILL BE WEAKENING AS THE FRONT PUSHES TOWARD THE KCMH/KLCK TAF SITES TOWARD 12Z SO NOT MUCH THUNDER MAY BE LEFT BY THE TIME IT REACHES THESE TERMINALS. OUTLOOK...MVFR CONDITIONS WITH LOCAL IFR VISIBILITIES EXPECTED IN SHOWERS FRIDAY MORNING. WEST WINDS GUSTING TO 30 KT EXPECTED FRIDAY. && .ILN WATCHES/WARNINGS/ADVISORIES... OH...NONE. KY...NONE. IN...NONE. && $$ SYNOPSIS...HATZOS NEAR TERM...HATZOS SHORT TERM...HATZOS LONG TERM...FRANKS AVIATION...HICKMAN
AREA FORECAST DISCUSSION
NWS SIOUX FALLS SD
425 AM CDT THU APR 18 2013 .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 420 AM CDT THU APR 18 2013 UPPER LEVEL SUPPORT RAPIDLY EXPANDING NORTHWARD THIS MORNING AND WILL MAXIMIZE OVER SOUTHEAST SOUTH DAKOTA INTO NORTHWEST IOWA BY ABOUT 18Z TODAY. INSTABILITY FROM ABOUT 850MB TO 700MB OVER SOUTHEAST NEBRASKA INTO WESTERN IOWA ALLOWING CONVECTIVE ELEMENTS TO DEVELOP IN THOSE AREAS BUT THE INSTABILITY NOT REAL IMPRESSIVE SO NOT THINKING THAT IT WILL PLAY A HUGE ROLE IN THE WEATHER OVER THE NEXT 24 HOURS. DO EXPECT SOME INCREASED RAINFALL RATES IN NORTHWEST IOWA HOWEVER AND THE MAIN CONCERN WILL BE A RIBBON OF FREEZING PRECIPITATION AND SLEET FROM SIOUX CITY TOWARDS SHELDON INTO PARTS OF SOUTHWEST MINNESOTA THROUGH ABOUT LATE MORNING. FARTHER WEST IT SHOULD BE MAINLY SNOW AND A BAND OF HEAVY SNOWFALL STILL LOOKS GOOD FROM YANKTON TO SIOUX FALLS INTO SOUTHWEST MINNESOTA. UPPER LEVEL PV ADVECTION MAXIMIZES THIS MORNING AND THE 750MB TO 650MB FRONT IS PLANTED RIGHT OVER SOUTHEAST SOUTH DAKOTA INTO SOUTHWEST MINNESOTA. WHILE THERE IS SOME INSTABILITY ABOVE THE FRONT IT IS NOT NEARLY AS IMPRESSIVE AS LAST WEEKS SYSTEM. SO AT THIS TIME NOT PLANNING ON ANY THUNDER SNOW BUT SNOWFALL RATES OF AN INCH AN HOUR AT TIMES STILL LIKELY. THE BEST CHANCE FOR THE HEAVIEST SNOWFALL RATES WILL BE FROM ABOUT 12Z THROUGH 19Z SHIFTING FROM FROM SOUTH TO NORTH. STILL EXPECT SNOW TO CONTINUE THROUGH THE REMAINDER OF THE AFTERNOON AND EVENING...DECREASING PRETTY QUICKLY FOR THE WEST TONIGHT. THE 21Z SREF HAS PRETTY GOOD CLUSTERING AROUND 8 TENTHS OF AN INCH OF LIQUID AROUND SIOUX FALLS WHILE THE LATEST GEM/ECMWF/NAM ARE CLOSER TO 6 TO 7 TENTHS OF LIQUID. THE 3Z SREF HAS DROPPED OFF QUITE A BIT WITH STORM TOTAL LIQUID AFTER 12Z THIS MORNING ABOUT 0.45...THIS TAKING AWAY THE 0.13 IT HAD IN BEFORE 12Z WHICH DOES NOT LOOK LIKE IT WILL OCCUR. IN FACT MOST AREAS WEST OF A YANKTON TO SLAYTON LINE LIKELY WILL GET ONLY A COUPLE OF TENTHS OR LESS THROUGH 12Z THIS MORNING WITH MAYBE AN INCH OR SO FROM THE JAMES VALLEY WEST. TAKING THIS INTO ACCOUNT WITH ALL OF THE MODELS LOOKS LIKE WE WILL SETTLE IN TO MORE OF A 4 TO 6 TENTHS LIQUID POTENTIAL. GIVEN SOME COMPACTION AND MELTING AS IT FALLS 4 TO 6 INCHES SEEMS ABOUT RIGHT FOR THE SIOUX FALLS AREA WITH AN INCH OR TWO MORE IN SOUTHWEST MINNESOTA. A LITTLE WORRIED THAT THE SNOWFALL FALLING DURING THE DAY VERSUS AT NIGHT LIKE LAST WEEK AND LESS INSTABILITY THAN THAT SYSTEM AS WELL AS SURFACE TEMPERATURES ABOUT 2-3 DEGREES WARMER WILL KEEP AMOUNTS ABOUT 4-5 INCHES. LATEST RUNS OF THE HRRR AS WELL AS THE RAP KEEP THE BETTER AMOUNTS JUST EAST AND NORTH OF THE INTERSTATE 29 CORRIDOR WHICH MATCHES FAIRLY WELL WITH THE MID LEVEL BOUNDARY...AROUND 700MB AND THE EDGE OF THE DRY SLOT. .LONG TERM...(FRIDAY THROUGH WEDNESDAY) ISSUED AT 420 AM CDT THU APR 18 2013 FRIDAY AND SATURDAY WILL CONTINUE TO SEE BELOW NORMAL TEMPERATURES ESPECIALLY WITH THE SNOW COVER. ANOTHER SYSTEM WILL BRING THE CHANCE FOR RAIN OR SNOW TO THE AREA SATURDAY AND SATURDAY NIGHT BUT IS NOT EXPECTED TO BE A MAJOR IMPACT. THE SUNDAY INTO MIDDLE OF NEXT WEEK PERIOD IS CHARACTERIZED BY CONTINUED BELOW NORMAL TEMPERATURES WITH TROUGHING OVER THE CENTRAL US. SUNDAY COULD ACTUALLY BE ONE OF THE WARMER DAYS WITH HIGHS GETTING INTO THE 50S OVER PORTIONS OF THE AREA. STAYED ON THE COOLER SIDE OF GUIDANCE FOR NOW...WITH THE THOUGHT THAT AT LEAST SOME SNOW COVER REMAINS OVER A GOOD PORTION OF THE CWA. BUT IF SNOW IS MAINLY GONE...SUNDAY COULD BE SEVERAL DEGREES WARMER THAN CURRENTLY FORECAST. AS THE THE LONGWAVE TROUGH BUILDS IN...OUR AREA WILL SEE MULTIPLE SHORTWAVES TRAVERSE THE AREA. THUS THE THE THREAT OF RAIN SHOWERS CONTINUE SUNDAY INTO SUNDAY NIGHT. NOT LOOKING AT A LOT OF QPF...BUT MOST PLACES SHOULD GET SOMETHING. COLD FRONT MOVES THROUGH MONDAY INTO MONDAY NIGHT. WITH THE MID LEVEL FRONT THE THREAT OF RAIN SHOWERS WILL CONTINUE. THERMAL PROFILES GET COLD ENOUGH THAT WE COULD SEE SOME SNOW MIX IN LATER MONDAY INTO MONDAY NIGHT...BUT AT THIS TIME WITH THE WAVE MORE PROGRESSIVE...DOES NOT LOOK LIKE WE SEE MUCH IN THE WAY OF ANY ACCUMULATING SNOW...BUT WILL HAVE TO MONITOR MODEL TRENDS. THE SYSTEM MOVES EAST ON TUESDAY...WHICH SHOULD LEAD TO A MAINLY DRY COUPLE DAYS...ALTHOUGH HIGHS WILL BE STUCK IN THE 40S ON TUESDAY WITH THE TROUGH OVERHEAD. A SLOW WARMING TREND SHOULD BEGIN BY WEDNESDAY...WITH HIGHS GETTING INTO THE UPPER 40S TO MID 50S. LONGER RANGE GUIDANCE CONTINUES TO SUGGEST A WARMING TREND LATER NEXT WEEK INTO THE WEEKEND...WITH ACTUAL SPRING LIKE WEATHER POSSIBLY FINALLY ARRIVING. && .AVIATION...(FOR THE 00Z TAFS THROUGH 00Z THURSDAY EVENING) ISSUED AT 629 PM CDT WED APR 17 2013 DETERIORATING CONDITIONS THROUGH THE NIGHT AS MIXED PRECIPITATION OVERSPREADS THE AREA. MAY HAVE SOME ISOLATED THUNDERSTORM ACTIVITY OVER NORTHWESTERN IOWA EARLY IN THE EVENING...OTHERWISE PRECIPITATION THAT DEVELOPS WILL BE MAINLY IN THE FORM OF SNOW THROUGH THE JAMES RIVER VALLEY...WITH A BAND OF MIXED PRECIPITATION EAST OF THIS AREA...THEN ALL RAIN THROUGH NORTHWESTERN IOWA. AS THE NIGHT PROGRESSES...PRECIPITATION WILL TRANSITION TO ALL SNOW FROM WEST TO EAST...WITH SNOW THEN PERSISTING INTO THURSDAY EVENING. IN ADDITION...NORTHWESTERLY WINDS WILL INCREASE TONIGHT AND TOMORROW...WITH GUSTS OF 35 TO 40 KTS ON THURSDAY AFTERNOON. && .FSD WATCHES/WARNINGS/ADVISORIES... SD...WINTER WEATHER ADVISORY UNTIL 1 AM CDT FRIDAY FOR SDZ038-039-050- 052>055-057>061-063>066-068>071. WINTER STORM WARNING UNTIL 1 AM CDT FRIDAY FOR SDZ040-056-062- 067. MN...WINTER WEATHER ADVISORY UNTIL 1 AM CDT FRIDAY FOR MNZ090. WINTER STORM WARNING UNTIL 1 AM CDT FRIDAY FOR MNZ071-072-080- 081-089-097-098. IA...WINTER WEATHER ADVISORY UNTIL 1 AM CDT FRIDAY FOR IAZ002-003- 012>014-020-021-031. WINTER STORM WARNING UNTIL 1 AM CDT FRIDAY FOR IAZ001. NE...WINTER WEATHER ADVISORY UNTIL 1 AM CDT FRIDAY FOR NEZ013-014. && $$ SHORT TERM...08 LONG TERM...CHENARD AVIATION...JM
AREA FORECAST DISCUSSION
NWS NASHVILLE TN
617 AM CDT THU APR 18 2013 .UPDATE...FOR 12Z AVIATION FORECAST .AVIATION... STRONG LINE OF CONVECTION FROM CHICAGO DOWN THROUGH SAINT LOUIS INTO FAR EASTERN OKLAHOMA AND EASTERN TEXAS WILL MOVE EAST TODAY AND BE ALONG THE MISSISSIPPII RIVER BY 23Z AND ALONG THE TENNESSEE RIVER BY 02Z AND INTERSTATE 65 AT 05Z AND ON THE PLATEAU BY 11Z. LOW LEVEL JET OUT AHEAD OF THE LINE ON THE ORDER OF 65 TO 70 KNOTS WILL PULL EAST WITH THE LINE TODAY AND TONIGHT. BOUNDARY LAYER WINDS ALREADY 45 KNOTS AT BNA THIS MORNING WILL LIKELY SUSTAIN THIS SPEED DURING THE DAY AND EVENING WITH SURFACE WINDS GUSTS TO 30 KNOTS DURING THE DAY AND INTO THE EVENING ACROSS THE MID STATE. WILL INCLUDE LOW LEVEL WIND SHEAR FOR THIS MORNING AT ALL TERMINALS. STRONG CAPPING INVERSION BASED AROUND 825 MBARS WILL PRECLUDE ANY THUNDERSTORM DEVELOPMENT UNTIL TONIGHT. ONCE SQUALL LINE PASSES TONIGHT LOOK FOR GUSTY WEST WINDS TO FOLLOW. BOYD && .PREV DISCUSSION... /ISSUED 400 AM CDT THU APR 18 2013/ ..MODERATE RISK OF SEVERE THUNDERSTORMS THIS EVENING INTO TONIGHT... DISCUSSION... FEW OVERALL CHANGES TO THE FORECAST OVER THE NEXT WEEK...WITH MAINLY SLIGHT ADJUSTMENTS TO TEMPS AND TIMING OF PRECIP. A LARGE H5 TROUGH OVER THE PLAINS STATES WILL SHIFT INTO THE MISSISSIPPI VALLEY TODAY THEN ACROSS THE TENNESSEE VALLEY TONIGHT...WITH AN ASSOCIATED STRONG COLD FRONT SWEEPING THROUGH THE MID STATE TONIGHT. BEFORE THE FRONT ARRIVES...ANOTHER SUMMER-LIKE DAY IS ON TAP WITH TEMPERATURES STARTING OUT IN THE 60S TO AROUND 70 THIS MORNING THEN WARMING UP INTO THE LOW TO MID 80S AREAWIDE THIS AFTERNOON. AS A SUB-1000MB SURFACE LOW TAKES SHAPE ACROSS THE MIDWEST...925MB WINDS WILL INCREASE ACROSS OUR REGION INTO THE 40-50KT RANGE TODAY LEADING TO GUSTY SOUTH WINDS AT THE SURFACE. ANTICIPATING SOUTH WINDS IN THE 15 TO 30 MPH RANGE DEVELOPING LATER THIS MORNING...THEN CONTINUING INTO THE AFTERNOON HOURS BEFORE SUBSIDING SOMEWHAT EARLY IN THE EVENING. OCCASIONAL GUSTS TO NEAR 40 MPH APPEAR LIKELY AS WELL BASED ON BUFKIT SOUNDINGS. SOUTH WINDS WILL INCREASE AGAIN LATER IN THE EVENING AS A SHARP PRESSURE GRADIENT MOVES ACROSS THE MID STATE AHEAD OF THE COLD FRONT. TO SIMPLIFY MATTERS...HAVE ISSUED A WIND ADVISORY FOR ALL ZONES BEGINNING LATER THIS MORNING AND CONTINUING THROUGH THE EARLY MORNING HOURS ON FRIDAY. SPC HAS PLACED AREAS ALONG AND WEST OF THE I-65 CORRIDOR IN A MODERATE RISK FOR SEVERE STORMS THURSDAY EVENING WITH A SLIGHT RISK TO THE EAST THURSDAY NIGHT. 00Z GFS/NAM/ECMWF AND LATEST HIGH RESOLUTION 4.0 KM WRF...NSSL WRF...AND HRRR ALL INDICATE A STRONG TO SEVERE QLCS WILL FORM LATER TODAY ALONG THE FRONT...REACHING THE TENNESSEE RIVER BY MID EVENING...I-65 CORRIDOR AROUND MIDNIGHT...AND EXIT EAST OF THE CWA NEAR/AFTER SUNRISE FRIDAY MORNING. MODELS CONTINUE TO DEPICT GENERALLY WEAK INSTABILITY AROUND 500 J/KG AHEAD OF THE LINE...BUT SOME GUIDANCE INDICATES A SURGE OF MID/UPPER 60S DEWPOINTS COMING NORTHWARD AHEAD OF THE QLCS WHICH COULD BUMP UP CAPE VALUES TO NEAR/OVER 1000 J/KG ACROSS WESTERN ZONES. REGARDLESS...IMPRESSIVE 0-3KM SRH STRENGTHENING INTO THE 500-800 M2/S2 RANGE AND VERY LONG CURVED HODOGRAPHS SUGGESTS A SIGNIFICANT DAMAGING WIND THREAT WITH THE LINE OF STORMS ALONG WITH SOME QLCS TORNADOES. HIGHEST RISK OF DAMAGING WINDS/TORNADOES IS EXPECTED TO BE ALONG/WEST OF I-65 IN THE 02-06Z TIMEFRAME ACROSS THE MODERATE RISK AREA...AS STORMS WILL ENCOUNTER INCREASINGLY LESS INSTABILITY AND WEAKENING SHEAR OFF TO THE EAST. STRATIFORM RAIN AND A FEW THUNDERSTORMS WILL CONTINUE MUCH OF THE NIGHT BEHIND THE QLCS WITH RAINFALL COMING TO AN END FROM WEST TO EAST FRIDAY MORNING. MUCH COOLER TEMPERATURES ARE ANTICIPATED FRIDAY AND SATURDAY WITH LOWS FALLING INTO THE MID TO UPPER 30S SATURDAY MORNING. WITH SURFACE RIDGE SETTLING OVER THE MID STATE...LIGHT TO CALM WINDS...AND DEWPOINTS FALLING INTO THE 20S AND 30S...PATCHY FROST APPEARS POSSIBLE FOR MUCH OF THE FORECAST AREA AND HAVE ADDED MENTION TO ZONES. AREA WILL BEGIN TO WARMUP FROM SUNDAY INTO EARLY NEXT WEEK AS SOUTHERLY FLOW BEGINS ANEW. FEW CHANGES WERE MADE IN THE EXTENDED FORECAST WITH NEXT CHANCE FOR RAIN AROUND TUESDAY/WEDNESDAY OF NEXT WEEK. && .OHX WATCHES/WARNINGS/ADVISORIES... WIND ADVISORY FROM 10 AM THIS MORNING TO 1 AM CDT FRIDAY FOR TNZ005>011-022>034-056>066-075-077>080-093>095. && $$ 01
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
630 AM CDT THU APR 18 2013 .SHORT TERM...(TODAY THROUGH TONIGHT) ISSUED AT 336 AM CDT THU APR 18 2013 MODERATE TO HEAVY RAINFALL AND FLOODING POTENTIAL FOR PORTIONS OF THE FORECAST AREA TODAY AND EVENTUAL CHANGE-OVER TO SNOW OVERNIGHT REMAIN THE MAIN CONCERNS IN THE SHORT TERM. WATER VAPOR IMAGERY/RAP 500MB ANALYSIS SHOW A DEEP TROUGH OF LOW PRESSURE EXTENDING FROM THE DAKOTAS INTO THE 4-CORNERS AREA. DEEP SOUTHERLY FETCH ON THE EAST SIDE OF THIS TROUGH WAS SENDING COPIOUS MOISTURE NORTHWARD TOWARD THE AREA. AN EMBEDDED VIGOROUS SHORTWAVE TROUGH WAS NOTED EJECTING NORTHEASTWARD OUT OF THE SOUTHERN PLAINS...INTERACTING WITH THE MOISTURE-RICH ENVIRONMENT. THIS WAVE WAS SPAWNING SOME EARLY MORNING SEVERE WEATHER ACROSS NORTHEAST OK/SOUTHWEST MO. NORTHERN FRINGES OF THIS WAVE WAS PUSHING SHOWERS/SCATTERED THUNDERSTORMS NORTHEAST ACROSS IA TOWARD SOUTHERN PORTIONS OF THE FORECAST AREA PER THE RADAR MOSAIC. OTHERWISE... SURFACE MAP HAS A SURFACE LOW OVER NORTHEAST OK WITH A WARM FRONT EXTENDING NORTHEAST ACROSS CENTRAL MO INTO SOUTHERN IL. STRONG LIFT AND MOISTURE TRANSPORT OVER THE WARM FRONT WAS ALSO PRODUCING A VIGOROUS SW-NE LINE CONVECTION FROM WEST CENTRAL IL TO NEAR CHICAGO...AND INTO SOUTHERN LOWER MI. OUR AREA WAS IN A TEMPORARY PRECIPITATION LULL FOR NOW. FOR TODAY...LOOK FOR THAT MAIN SHORTWAVE TROUGH OVER THE SOUTHERN PLAINS TO PUSH MORE RAIN INTO THE AREA THROUGH THIS MORNING WITH EMBEDDED THUNDERSTORMS MAINLY CONFINED MAINLY ALONG AND SOUTH OF I-90. ONCE THAT SHORTWAVE TROUGH/MAIN AXIS OF MOISTURE TRANSPORT MOVES EAST OF THE AREA BY LATER THIS MORNING...WILL LIKELY SEE A DIMINISHING TREND IN THE RAIN...PERHAPS GOING OVER TO DRIZZLE. FOR LATER INTO THIS AFTERNOON...WILL SEE DEFORMATION SHIELD RAIN SPREADING IN FROM WEST TO EAST AS THE MAIN LONG-WAVE UPPER LEVEL TROUGH PUSHES EAST FROM THE PLAINS TOWARD THE AREA. AS THE COLUMN COOLS DUE TO DYNAMIC COOLING...THERE COULD BE SOME FLAKES OF SNOW MIXING IN WEST OF THE MISSISSIPPI AFTER 5-6 PM. THEN FOR TONIGHT...CONTINUED DYNAMIC COOLING WILL TAKE PLACE AS THE UPPER TROUGH ROTATES ACROSS THE AREA. WITH THIS...PLAN ON A TRANSITION FROM RAIN TO SNOW FROM WEST TO EAST. RIGHT NOW...IT APPEARS 1 TO LOCALLY 2 INCHES OF SNOWFALL IS POSSIBLE FOR PORTIONS OF SOUTHEAST MINNESOTA INTO NORTH CENTRAL WISCONSIN. OTHER AREAS WILL LIKELY SEE LESS THAN A HALF INCH OF SLUSHY ACCUMULATION. IMPACTS FROM RAINFALL INTO THIS EVENING WILL BE DISCUSSED IN THE HYDROLOGY SECTION BELOW. .LONG TERM...(FRIDAY THROUGH WEDNESDAY) ISSUED AT 336 AM CDT THU APR 18 2013 FRIDAY LOOKS LIKE A RAW DAY ACROSS THE FORECAST AREA AS THE TROUGH AND ASSOCIATED DEFORMATION SNOW/RAIN AREA MOVE ACROSS THE REGION ALONG WITH BRISK NORTHWEST WINDS IN THE 15 TO 30 MPH RANGE. PLAN ON PERHAPS ANOTHER 1/2-1 INCH OF SLUSHY ACCUMULATION MAINLY NORTH OF I-94. OTHERWISE...THE BRISK NORTHWEST WINDS COMBINED WITH HIGHS ONLY IN THE MIDDLE 30S TO LOWER 40S WILL MAKE IT FEEL MORE LIKE THE UPPER 20S/LOWER 30S. FINALLY...SOME DRIER AIR MOVES INTO THE AREA FRIDAY NIGHT THROUGH SATURDAY AS HIGH PRESSURE TAKES CONTROL. THIS WILL BE A BRIEF RESPITE THROUGH AS YET ANOTHER AREA OF LOW PRESSURE WILL MOVE ACROSS THE NORTHERN PLAINS AND ACROSS THE AREA SATURDAY NIGHT THROUGH MONDAY. ISENTROPIC LIFT AHEAD OF THE WAVE SATURDAY NIGHT WILL YIELD A CHANCE OF RAIN AND SNOW AND ALL RAIN DURING THE DAY SUNDAY INTO SUNDAY NIGHT. ON MONDAY...A COLD FRONT WILL PUSH SOUTHEAST INTO THE AREA WHILE A WAVE OF LOW PRESSURE RIPPLES NORTHEAST ALONG THIS BAROCLINIC ZONE FOR A CHANCE OF SHOWERS/THUNDER. THUNDER CHANCES LOOK HIGHER ALONG AND SOUTH OF I-90 WHERE 0-3KM MUCAPE CLIMBS INTO THE 500-900J/KG RANGE. PRECIPITATION CHANCES WILL CONTINUE STRAIGHT THROUGH WEDNESDAY AS BAROCLINICITY LINGERS ACROSS THE AREA WITH A COUPLE WAVES OF LOW PRESSURE RIPPLING UP ALONG IT. COULD BE SOME SNOW MIXING IN DURING THE NIGHT MONDAY NIGHT AND ESPECIALLY TUESDAY NIGHT. OTHERWISE...BESIDES RELATIVELY MILDER DAYS ON SUNDAY MONDAY WITH HIGHS MAINLY IN THE 50S...UNSEASONABLY COOL SPRING SO FAR WILL CONTINUE WITH HIGHS MAINLY IN THE 40S. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z FRIDAY MORNING) ISSUED AT 630 AM CDT THU APR 18 2013 SURFACE LOW WILL LIFT NORTHEAST INTO SOUTHERN WISCONSIN THIS AFTERNOON AND THEN TO NORTHERN LAKE MICHIGAN TONIGHT. RAIN WILL CONTINUE AT TE TAF SITES THROUGH THE EARLY MORNING HOURS...WITH THE 18.08Z HRRR SHOWING A LULL IN THE ACTIVITY FROM MID MORNING INTO THE AFTERNOON...WHERE ONLY DRIZZLE WILL OCCUR. HOWEVER AS RAIN LIGHTENS UP...VISIBILITIES WILL LIKELY DROP BACK INTO THE IFR CATEGORY. AS THE DEFORMATION BAND OF PRECIPITATION MOVES IN LATER THIS AFTERNOON...THE RAIN WILL MIX WITH AND THEN CHANGE TO SNOW TONIGHT. THIS CHANGEOVER LOOKS TO OCCUR AROUND 03Z AT KRST AND BETWEEN 05Z-08Z AT KLSE. ONCE THIS OCCURS EXPECT LOWER END MVFR CEILINGS AND IFR VISIBILITIES. && .HYDROLOGY...TODAY INTO TONIGHT ISSUED AT 336 AM CDT THU APR 18 2013 FLOOD WATCH IN EFFECT THROUGH THURSDAY NIGHT FOR PORTIONS NORTHEAST IA INTO SOUTHWEST AND CENTRAL WI. RAINFALL OVER THE LAST 24 HOURS RANGED FROM 1/2 INCH TO AROUND 1.5 INCHES ACROSS NORTHEAST IA INTO SOUTHWEST WI. SO FAR...SOME SIGNIFICANT RISES NOTED ON RIVERS ACROSS THIS AREA...BUT NO FLOODING YET. HOWEVER...WITH ANOTHER SLUG OF 1/4 TO 1/2 INCH/LOCALLY HIGHER AMOUNTS...WILL HOLD ONTO THE FLOOD WATCH ACROSS THIS AREA FOR THE POTENTIAL OF SOME FLOODING. RIGHT NOW...THE KICKAPOO RIVER IS OF MOST CONCERN IF THIS ADDITIONAL RAINFALL AMOUNT IS REALIZED OVER THE BASIN. OTHER RIVERS REMAIN HIGH WITH SOME FLOODING FROM RECENT RAINFALL AND SNOWMELT...SUCH AS THE BLACK RIVER AND TREMPEALEAU RIVERS. IN ADDITION...THERE WILL BE PONDING OF WATER ON ROADWAYS ALONG WITH STANDING WATER IN LOW LYING AND POOR DRAINAGE AREAS. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...FLOOD WATCH THROUGH LATE TONIGHT FOR WIZ042>044-053>055-061. MN...NONE. IA...FLOOD WATCH THROUGH LATE TONIGHT FOR IAZ011-029-030. && $$ SHORT TERM...DAS LONG TERM...DAS AVIATION...RABERDING HYDROLOGY...DAS
AREA FORECAST DISCUSSION
NWS MOUNT HOLLY NJ
1040 AM EDT THU APR 18 2013 .SYNOPSIS... HIGH PRESSURE WILL MOVE OFF THE COAST OF NOVA SCOTIA LATER TODAY, ALLOWING A WARM FRONT TO LIFT THROUGH THE AREA THIS EVENING. A STRONG COLD FRONT WILL MOVE THROUGH THE AREA FRIDAY NIGHT INTO EARLY SATURDAY MORNING AS AN AREA OF LOW PRESSURE MOVES THROUGH THE GREAT LAKES AND INTO EASTERN CANADA. HIGH PRESSURE BUILDS ACROSS THE NORTHEAST SUNDAY INTO MONDAY. A WEAK DISTURBANCE MAY DEVELOP OFF THE SOUTHEAST COAST AND AFFECT THE AREA LATE MONDAY INTO TUESDAY. ANOTHER COLD FRONT IS FORECAST TO AFFECT THE AREA LATE WEDNESDAY OR THURSDAY. && .NEAR TERM /THROUGH TONIGHT/... TODAY...930 AM ESTF UPDATE: POPS CONTINUE TO BE BOOSTED OVER E PA AND E MD AND NOW NEARLY 55 PCT IN SOME AREAS AS SHOWERS BECOME MORE EVIDENT ON RADAR AND NOT TO DISAPPEAR IN THE GENERAL WAA PATTERN. TEMPS WERE SLIGHTLY ADJUSTED THROUGH MIDDAY...BUT WITH NO CHANGE TO THE OVERALL FCST HIGHS FROM THE MID SHIFT FCST. RAP IS THE RUNNING A LITTLE SLOW ON THE SHOWERS. ALREADY HAVING TRACED IN KILG AND SOON SPRINKLES IN PHL PER TDWR TPHL. SHOWERS MOSTLY E MD AND DE THIS MORNING THRU E PA THIS AFTN AND FOR NOW CONSIDERED SCT AT ANY ONE TIME, BUT MANY AREAS WILL TRACE TO .01 TODAY WITH A FEW .10 POSSIBLE E PA. BLAME IT ON A WARM FRONT...GENERAL WAA. CONTINUE TO NOTICE A SPIKE IN RH EARLY THIS AFTN..VIA TSECS...WHICH SIGNALS BETTER LIFT. RAP SUGGESTS TOPS TO MAYBE 17000 FT. THE .01 TO .02/HR SHOWERS INCREASING NOW OVER E MD INTO N DEL WILL BECOME THEIR MOST EXPANSIVE DURING THE EARLY AFTN AS THEY MOVE THROUGH E PA AND W NJ. FOG ADDED TO COASTAL DE AND FAR SNJ. TONIGHT...CONSIDERABLE LOW CLOUDINESS AND A STRONGER SLY FLOW AS THE CDFNT TO THE W ADVANCES TWD THE REGION. THERE ARE MODEL INDICATIONS OF A DENSE FOG PROBLEM HERE AND THERE DESPITE BL WINDS OF ALMOST 20 KT. SUSPECT CIGS WILL LOWER DURING THE NIGHT WITH VSBY AT ITS LOWEST NEAR 1 MI TOWARD DAWN FRIDAY. FOR NOW...PATCHY FOG HAS BEEN ADDED TO THE FCST LATER TONIGHT. && .SHORT TERM /FRIDAY/... FRIDAY...EARLY IN THE DAY FOG LIFTS AS WE BECOME MORE DEFINED WITHIN THE WARM SECTOR OF THE SYSTEM, AHEAD OF THE APPROACHING COLD FRONT. WE EXPECT A WARM, BREEZY MIDDAY/AFTERNOON. A WEAK SHORT WAVE MAY CROSS THE AREA VERY LATE IN THE DAY AHEAD OF THE APPROACHING COLD FRONT WHICH COMBINED WITH SOME WEAK AFTERNOON INSTABILITY MAY SPARK A FEW SHOWERS/THUNDERSTORMS. THERE IS A GOOD CHANCE OF SSW GUSTS 30-40 KT ON THE NON WATER INFLUENCED REGION OF OUR INTERIOR MID ALTC CWA 18Z-21Z FRIDAY. THIS PER SEVERAL RUNS OF THE NAM AND WITH SOME GFS SUPPORT. && .LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/... FRIDAY NIGHT...THE COLD FRONT IS FORECAST TO MOVE INTO OUR WESTERN AREAS AROUND OR SHORTLY AFTER SUNSET AND MOVE EASTWARD THROUGH THE NIGHT. WITH PW VALUES NEAR 1.5 INCHES, A PERIOD OF HEAVY RAIN IS POSSIBLE. THERE IS SOME WEAK INSTABILITY AHEAD OF THE FRONT...MUCAPES NEAR 200-300 J/KG, LI`S NEAR -1 TO -2, K-INDEX VALUES IN THE 30S...SO SOME EMBEDDED THUNDERSTORMS ARE POSSIBLE. RAINFALL AMOUNTS WILL BE ENHANCED WHERE/IF THUNDERSTORMS DO DEVELOP. THE GOOD NEWS IS THE FRONT IS FORECAST TO BE FAIRLY PROGRESSIVE AND MOVE THROUGH THE AREA OVERNIGHT AND BE OFFSHORE BY SUNRISE SATURDAY WHICH SHOULD LIMIT ANY FLOOD POTENTIAL TO THE URBAN/POOR DRAINAGE TYPE. SOME LINGERING LIGHT RAIN IS POSSIBLE, MAINLY TOWARD THE COAST, EARLY SATURDAY AS THE FRONT PUSHES FARTHER AWAY FROM THE AREA. BEHIND THE FRONT, A GUSTY WESTERLY FLOW WILL DEVELOP. HIGH PRESSURE WILL BUILD ACROSS THE NORTHEAST SATURDAY NIGHT INTO SUNDAY WHICH WILL PROVIDE DRY WEATHER FOR THE REGION. THE HIGH TRIES TO RETREAT NORTHEASTWARD ON MONDAY, BUT WE MAY STILL REMAIN UNDER THE GRASP OF THE FAR SOUTHERN EXTEND OF THE HIGH. THICKNESSES FAIL TO RECOVER SUNDAY INTO MONDAY, AND WITH AN EASTERLY FLOW ACROSS THE AREA TEMPERATURES ARE FORECAST TO BE A FEW DEGREES BELOW NORMAL. AS THE HIGH RETREATS MONDAY INTO MONDAY NIGHT, A WEAK SURFACE TROUGH IS FORECAST TO DEVELOP OFFSHORE OF THE SOUTHEAST STATES AND BEGIN NOSING ITS WAY TOWARD OUR AREA. WITH A COUPLE OF WEAK SHORT WAVES MOVING ACROSS THE AREA, WE COULD HAVE SOME PRECIPITATION DEVELOP AND MOVE ACROSS THE AREA. SCATTERED SHOWERS COULD CONTINUE INTO TUESDAY WITH A COUPLE OF WEAK SHORT WAVES EMBEDDED IN THE SOUTHWEST FLOW ALOFT. ANOTHER COLD FRONT IS FORECAST TO AFFECT THE AREA SOMETIME LATE WEDNESDAY INTO THURSDAY. THIS COULD BRING ANOTHER ROUND OF MODERATE TO HEAVY RAINFALL TO THE AREA. && .AVIATION /15Z THURSDAY THROUGH MONDAY/... THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY AND SURROUNDING AREAS. TODAY...AREAS OF IFR CIGS POSSIBLY TO SPREAD INTO PHL/ILG MID OR LATE MORNING. CIGS WILL BE AN OCNL PBLM TODAY AND CERTAINLY NOT AN ALL VFR DAY. ESE WIND INCREASING WITH GUSTS THIS AFTN TO NEAR 20 KT. PLEASE FOLLOW TAF ADJUSTMENTS AS THE DETERIORATING CONDITIONS UNFOLD. TONIGHT...IFR CIGS BECOMING WIDESPREAD WITH VSBY LOWERING TO LESS THAN A MILE LATER AT NIGHT WITH A SMALL CHC OF LIFR CONDS IN PATCHY DENSE FOG...ESPECIALLY E PA AND COASTAL S NJ. THIS WITH SREF CIG VSBY PROB SUPPORT FROM THEN 09Z/18 SREF. MANY TAFS HAVE BEEN AMENDED AROUND 14Z FOR THIS MUCH LOWER FORECAST CONDITION LATER TONIGHT. NEW 12Z NAM IS HIGHLY SUPPORTIVE OF STRATUS EVENTUALLY DESCENDING TO THE DECK IN LIFR CONDS OF FOG. THE KPHL TAF HAS BEEN ADJUSTED WITH FOG LATE. 18Z TAFS WILL ATTEMPT A MORE COMPLETE PICTURE OF ANTICIPATED IFR-LIFR CONDITIONS LATER THU NIGHT-FRI MORNING. FRIDAY...IFR CONDITIONS EARLY IN DRIZZLE FOG WITH POSSIBLE VFR LATE. CHANCE OF RAIN/THUNDERSTORMS BY AFTERNOON. GUSTY SOUTH WINDS AROUND 25-30 KNOTS POSSIBLE. LLWS POSSIBLE KACY LATE IN THE DAY. OUTLOOK... FRIDAY NIGHT...MVFR/IFR CONDITIONS EXPECTED WITH A PERIOD OF HEAVY RAIN AND THUNDERSTORMS POSSIBLE. SATURDAY...LINGERING SHOWERS AND POSSIBLE MVFR/IFR EARLY, MAINLY TOWARD THE COAST. IMPROVING TO VFR DURING THE DAY. GUSTY WEST WINDS 20-25 KNOTS. SATURDAY NIGHT-SUNDAY NIGHT...VFR CONDITIONS EXPECTED. MONDAY...MOSTLY VFR, POSSIBLE NEAR MVFR WITH SHOWERS. && .MARINE... FOG HAS BEEN ADDED TO THE FCST IN THE 930 AM PACKAGE. A WARM FRONT WILL MOVE BY TO THE N TODAY AND SELY FLOW WILL BECOME SLY AND INCREASE WELL INTO TONIGHT. THIS WILL CAUSE SEAS TO INCREASE AS WELL. THEREFORE, A SCA IS BEING RAISED BEGINNING AT 19/00Z. AT THIS POINT, IT IS ONLY FOR THE OCEAN, BUT MAY NEED TO BE EXPANDED FOR AT LEAST THE LOWER PORTION OF DEL BAY, BUT CONFIDENCE IS LOWER HERE. OUTLOOK... A STRONG COLD FRONT WILL MOVE ACROSS THE WATERS FRIDAY NIGHT INTO SATURDAY. WINDS ARE EXPECTED TO INCREASE AHEAD OF THE FRONT, AND COULD APPROACH GALE FORCE. THERE IS A STRONG FLOW ABOVE THE SURFACE, BUT IT MAY HAVE TROUBLE MIXING DOWN IN THE SOUTHERLY FLOW. FOR NOW, A SMALL CRAFT ADVISORY WILL BE IN EFFECT, AND WE WILL LET THE NEXT SHIFT SEE IF A GALE WARNING WILL BE NEEDED. ADVISORY LEVELS WINDS AND/OR SEAS WILL LIKELY CONTINUE INTO A PART OF SATURDAY. AS HIGH PRESSURE BUILDS ACROSS THE NORTHEAST THEN OFFSHORE EARLY NEXT WEEK, AN EASTERLY FLOW WILL DEVELOP ACROSS THE AREA. WINDS COULD CONTINUE TO GUST NEAR ADVISORY LEVELS THROUGH MONDAY, AND SEAS COULD REMAIN AROUND 4-5 FEET OR HIGHER WITH THE EASTERLY FETCH. && .PHI WATCHES/WARNINGS/ADVISORIES... PA...NONE. NJ...NONE. DE...NONE. MD...NONE. MARINE...SMALL CRAFT ADVISORY FROM 8 PM THIS EVENING TO 8 PM EDT FRIDAY FOR ANZ450>455. && $$ SYNOPSIS...DRAG/ROBERTSON NEAR TERM...DRAG 1039 SHORT TERM...DRAG/NIERENBERG 1039 LONG TERM...ROBERTSON AVIATION...DRAG/ROBERTSON 1039 MARINE...DRAG/NIERENBERG/ROBERTSON
AREA FORECAST DISCUSSION
NWS MOUNT HOLLY NJ
943 AM EDT THU APR 18 2013 .SYNOPSIS... HIGH PRESSURE WILL MOVE OFF THE COAST OF NOVA SCOTIA LATER TODAY, ALLOWING A WARM FRONT TO LIFT THROUGH THE AREA THIS EVENING. A STRONG COLD FRONT WILL MOVE THROUGH THE AREA FRIDAY NIGHT INTO EARLY SATURDAY MORNING AS AN AREA OF LOW PRESSURE MOVES THROUGH THE GREAT LAKES AND INTO EASTERN CANADA. HIGH PRESSURE BUILDS ACROSS THE NORTHEAST SUNDAY INTO MONDAY. A WEAK DISTURBANCE MAY DEVELOP OFF THE SOUTHEAST COAST AND AFFECT THE AREA LATE MONDAY INTO TUESDAY. ANOTHER COLD FRONT IS FORECAST TO AFFECT THE AREA LATE WEDNESDAY OR THURSDAY. && .NEAR TERM /THROUGH TONIGHT/... TODAY...930 AM ESTF UPDATE: POPS CONTINUE TO BE BOOSTED OVER E PA AND E MD AND NOW NEARLY 55 PCT IN SOME AREAS AS SHOWERS BECOME MORE EVIDENT ON RADAR AND NOT TO DISAPPEAR IN THE GENERAL WAA PATTERN. TEMPS WERE SLIGHTLY ADJUSTED THROUGH MIDDAY...BUT WITH NO CHANGE TO THE OVERALL FCST HIGHS FROM THE MID SHIFT FCST. RAP IS THE RUNNING A LITTLE SLOW ON THE SHOWERS. ALREADY HAVING TRACED IN KILG AND SOON SPRINKLES IN PHL PER TDWR TPHL. SHOWERS MOSTLY E MD AND DE THIS MORNING THRU E PA THIS AFTN AND FOR NOW CONSIDERED SCT AT ANY ONE TIME, BUT MANY AREAS WILL TRACE TO .01 TODAY WITH A FEW .10 POSSIBLE E PA. BLAME IT ON A WARM FRONT...GENERAL WAA. CONTINUE TO NOTICE A SPIKE IN RH EARLY THIS AFTN..VIA TSECS...WHICH SIGNALS BETTER LIFT. RAP SUGGESTS TOPS TO MAYBE 17000 FT. THE .01 TO .02/HR SHOWERS INCREASING NOW OVER E MD INTO N DEL WILL BECOME THEIR MOST EXPANSIVE DURING THE EARLY AFTN AS THEY MOVE THROUGH E PA AND W NJ. FOG ADDED TO COASTAL DE AND FAR SNJ. TONIGHT...CONSIDERABLE LOW CLOUDINESS AND A STRONGER SLY FLOW AS THE CDFNT TO THE W ADVANCES TWD THE REGION. THERE ARE MODEL INDICATIONS OF A DENSE FOG PROBLEM HERE AND THERE DESPITE BL WINDS OF ALMOST 20 KT. SUSPECT CIGS WILL LOWER DURING THE NIGHT WITH VSBY AT ITS LOWEST NEAR 1 MI TOWARD DAWN FRIDAY. FOR NOW...PATCHY FOG HAS BEEN ADDED TO THE FCST LATER TONIGHT. && .SHORT TERM /FRIDAY/... FRIDAY...EARLY IN THE DAY FOG LIFTS AS WE BECOME MORE DEFINED WITHIN THE WARM SECTOR OF THE SYSTEM, AHEAD OF THE APPROACHING COLD FRONT. WE EXPECT A WARM, BREEZY MIDDAY/AFTERNOON. A WEAK SHORT WAVE MAY CROSS THE AREA VERY LATE IN THE DAY AHEAD OF THE APPROACHING COLD FRONT WHICH COMBINED WITH SOME WEAK AFTERNOON INSTABILITY MAY SPARK A FEW SHOWERS/THUNDERSTORMS. && .LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/... FRIDAY NIGHT...THE COLD FRONT IS FORECAST TO MOVE INTO OUR WESTERN AREAS AROUND OR SHORTLY AFTER SUNSET AND MOVE EASTWARD THROUGH THE NIGHT. WITH PW VALUES NEAR 1.5 INCHES, A PERIOD OF HEAVY RAIN IS POSSIBLE. THERE IS SOME WEAK INSTABILITY AHEAD OF THE FRONT...MUCAPES NEAR 200-300 J/KG, LI`S NEAR -1 TO -2, K-INDEX VALUES IN THE 30S...SO SOME EMBEDDED THUNDERSTORMS ARE POSSIBLE. RAINFALL AMOUNTS WILL BE ENHANCED WHERE/IF THUNDERSTORMS DO DEVELOP. THE GOOD NEWS IS THE FRONT IS FORECAST TO BE FAIRLY PROGRESSIVE AND MOVE THROUGH THE AREA OVERNIGHT AND BE OFFSHORE BY SUNRISE SATURDAY WHICH SHOULD LIMIT ANY FLOOD POTENTIAL TO THE URBAN/POOR DRAINAGE TYPE. SOME LINGERING LIGHT RAIN IS POSSIBLE, MAINLY TOWARD THE COAST, EARLY SATURDAY AS THE FRONT PUSHES FARTHER AWAY FROM THE AREA. BEHIND THE FRONT, A GUSTY WESTERLY FLOW WILL DEVELOP. HIGH PRESSURE WILL BUILD ACROSS THE NORTHEAST SATURDAY NIGHT INTO SUNDAY WHICH WILL PROVIDE DRY WEATHER FOR THE REGION. THE HIGH TRIES TO RETREAT NORTHEASTWARD ON MONDAY, BUT WE MAY STILL REMAIN UNDER THE GRASP OF THE FAR SOUTHERN EXTEND OF THE HIGH. THICKNESSES FAIL TO RECOVER SUNDAY INTO MONDAY, AND WITH AN EASTERLY FLOW ACROSS THE AREA TEMPERATURES ARE FORECAST TO BE A FEW DEGREES BELOW NORMAL. AS THE HIGH RETREATS MONDAY INTO MONDAY NIGHT, A WEAK SURFACE TROUGH IS FORECAST TO DEVELOP OFFSHORE OF THE SOUTHEAST STATES AND BEGIN NOSING ITS WAY TOWARD OUR AREA. WITH A COUPLE OF WEAK SHORT WAVES MOVING ACROSS THE AREA, WE COULD HAVE SOME PRECIPITATION DEVELOP AND MOVE ACROSS THE AREA. SCATTERED SHOWERS COULD CONTINUE INTO TUESDAY WITH A COUPLE OF WEAK SHORT WAVES EMBEDDED IN THE SOUTHWEST FLOW ALOFT. ANOTHER COLD FRONT IS FORECAST TO AFFECT THE AREA SOMETIME LATE WEDNESDAY INTO THURSDAY. THIS COULD BRING ANOTHER ROUND OF MODERATE TO HEAVY RAINFALL TO THE AREA. && .AVIATION /14Z THURSDAY THROUGH MONDAY/... THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY AND SURROUNDING AREAS. TODAY...AREAS OF IFR CIGS POSSIBLY TO SPREAD INTO PHL/ILG MID OR LATE MORNING. CIGS WILL BE AN OCNL PBLM TODAY AND CERTAINLY NOT AN ALL VFR DAY. ESE WIND INCREASING WITH GUSTS THIS AFTN TO NEAR 20 KT. PLEASE FOLLOW TAF ADJUSTMENTS AS THE DETERIORATING CONDITIONS UNFOLD. TONIGHT...IFR CIGS BECOMING WIDESPREAD WITH VSBY LOWERING TO LESS THAN A MILE LATER AT NIGHT WITH A SMALL CHC OF LIFR CONDS IN PATCHY DENSE FOG...ESPECIALLY E PA AND COASTAL S NJ. THIS WITH SREF CIG VSBY PROB SUPPORT FROM THEN 09Z/18 SREF. THE KPHL TAF HAS BEEN ADJUSTED WITH FOG LATE. 18Z TAFS WILL ATTEMPT A MORE COMPLETE PICTURE OF ANTICIPATED IFR-LIFR CONDITIONS LATER THU NIGHT-FRI MORNING. FRIDAY...IFR CONDITIONS EARLY IN DRIZZLE FOG WITH POSSIBLE VFR LATE. CHANCE OF RAIN/THUNDERSTORMS BY AFTERNOON. GUSTY SOUTH WINDS AROUND 25-30 KNOTS POSSIBLE. LLWS POSSIBLE KACY LATE IN THE DAY. OUTLOOK... FRIDAY NIGHT...MVFR/IFR CONDITIONS EXPECTED WITH A PERIOD OF HEAVY RAIN AND THUNDERSTORMS POSSIBLE. SATURDAY...LINGERING SHOWERS AND POSSIBLE MVFR/IFR EARLY, MAINLY TOWARD THE COAST. IMPROVING TO VFR DURING THE DAY. GUSTY WEST WINDS 20-25 KNOTS. SATURDAY NIGHT-SUNDAY NIGHT...VFR CONDITIONS EXPECTED. MONDAY...MOSTLY VFR, POSSIBLE NEAR MVFR WITH SHOWERS. && .MARINE... FOG HAS BEEN ADDED TO THE FCST IN THE 930 AM PACKAGE. A WARM FRONT WILL MOVE BY TO THE N TODAY AND SELY FLOW WILL BECOME SLY AND INCREASE WELL INTO TONIGHT. THIS WILL CAUSE SEAS TO INCREASE AS WELL. THEREFORE, A SCA IS BEING RAISED BEGINNING AT 19/00Z. AT THIS POINT, IT IS ONLY FOR THE OCEAN, BUT MAY NEED TO BE EXPANDED FOR AT LEAST THE LOWER PORTION OF DEL BAY, BUT CONFIDENCE IS LOWER HERE. OUTLOOK... A STRONG COLD FRONT WILL MOVE ACROSS THE WATERS FRIDAY NIGHT INTO SATURDAY. WINDS ARE EXPECTED TO INCREASE AHEAD OF THE FRONT, AND COULD APPROACH GALE FORCE. THERE IS A STRONG FLOW ABOVE THE SURFACE, BUT IT MAY HAVE TROUBLE MIXING DOWN IN THE SOUTHERLY FLOW. FOR NOW, A SMALL CRAFT ADVISORY WILL BE IN EFFECT, AND WE WILL LET THE NEXT SHIFT SEE IF A GALE WARNING WILL BE NEEDED. ADVISORY LEVELS WINDS AND/OR SEAS WILL LIKELY CONTINUE INTO A PART OF SATURDAY. AS HIGH PRESSURE BUILDS ACROSS THE NORTHEAST THEN OFFSHORE EARLY NEXT WEEK, AN EASTERLY FLOW WILL DEVELOP ACROSS THE AREA. WINDS COULD CONTINUE TO GUST NEAR ADVISORY LEVELS THROUGH MONDAY, AND SEAS COULD REMAIN AROUND 4-5 FEET OR HIGHER WITH THE EASTERLY FETCH. && .PHI WATCHES/WARNINGS/ADVISORIES... PA...NONE. NJ...NONE. DE...NONE. MD...NONE. MARINE...SMALL CRAFT ADVISORY FROM 8 PM THIS EVENING TO 8 PM EDT FRIDAY FOR ANZ450>455. && $$ SYNOPSIS...DRAG/ROBERTSON NEAR TERM...DRAG 942 SHORT TERM...DRAG/NIERENBERG 942 LONG TERM...ROBERTSON AVIATION...DRAG/ROBERTSON 942 MARINE...DRAG/NIERENBERG/ROBERTSON
AREA FORECAST DISCUSSION
NWS MOUNT HOLLY NJ
854 AM EDT THU APR 18 2013 .SYNOPSIS... HIGH PRESSURE WILL MOVE OFF THE COAST OF NOVA SCOTIA LATER TODAY, ALLOWING A WARM FRONT TO LIFT THROUGH THE AREA THIS EVENING. A STRONG COLD FRONT WILL MOVE THROUGH THE AREA FRIDAY NIGHT INTO EARLY SATURDAY MORNING AS AN AREA OF LOW PRESSURE MOVES THROUGH THE GREAT LAKES AND INTO EASTERN CANADA. HIGH PRESSURE BUILDS ACROSS THE NORTHEAST SUNDAY INTO MONDAY. A WEAK DISTURBANCE MAY DEVELOP OFF THE SOUTHEAST COAST AND AFFECT THE AREA LATE MONDAY INTO TUESDAY. ANOTHER COLD FRONT IS FORECAST TO AFFECT THE AREA LATE WEDNESDAY OR THURSDAY. && .NEAR TERM /THROUGH TONIGHT/... 838 AM ESTF UPDATE A LITTLE EARLY FOR ISOLATED AND OR SCT SHOWERS... MOSTLY E MD THIS MORNING AND E PA THIS AFTN PER RAP AND MULTIPLE MODELS SPEWING MINOR AMTS OF NUISANCE SHOWERS. ALSO INCREASED GUSTS THIS AFTN ACROSS E PA TO THE DEL VALLEY. BLAME IT ON A WARM FRONT...GENERAL WAA. CONTINUE TO NOTICE A SPIKE IN RH EARLY THIS AFTN..VIA TSECS...WHICH SIGNALS BETTER LIFT. RAP SUGGESTS TOPS TO MAYBE 17000 FT. .01 TO .02/HR SHOWERS INCREASING NOW OVER E MD INTO N DEL WILL BECOME THEIR MOST EXPANSIVE DURING THE EARLY AFTN AS THEY MOVE THROUGH E PA AND W NJ. TONIGHT...CONSIDERABLE LOW CLOUDINESS AND A STRONGER SLY FLOW AS THE CDFNT TO THE W ADVANCES TWD THE REGION. THERE ARE MODEL INDICATIONS OF A DENSE FOG PROBLEM HERE AND THERE DESPITE BL WINDS OF ALMOST 20 KT. SUSPECT CIGS WILL LOWER DURING THE NIGHT WITH VSBY AT ITS LOWEST NEAR 1 MI TOWARD DAWN FRIDAY. && .SHORT TERM /FRIDAY/... FRIDAY...EARLY IN THE DAY FOG LIFTS AS WE BECOME MORE DEFINED WITHIN THE WARM SECTOR OF THE SYSTEM, AHEAD OF THE APPROACHING COLD FRONT. WE EXPECT A WARM, BREEZY MIDDAY/AFTERNOON. A WEAK SHORT WAVE MAY CROSS THE AREA VERY LATE IN THE DAY AHEAD OF THE APPROACHING COLD FRONT WHICH COMBINED WITH SOME WEAK AFTERNOON INSTABILITY MAY SPARK A FEW SHOWERS/THUNDERSTORMS. && .LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/... FRIDAY NIGHT...THE COLD FRONT IS FORECAST TO MOVE INTO OUR WESTERN AREAS AROUND OR SHORTLY AFTER SUNSET AND MOVE EASTWARD THROUGH THE NIGHT. WITH PW VALUES NEAR 1.5 INCHES, A PERIOD OF HEAVY RAIN IS POSSIBLE. THERE IS SOME WEAK INSTABILITY AHEAD OF THE FRONT...MUCAPES NEAR 200-300 J/KG, LI`S NEAR -1 TO -2, K-INDEX VALUES IN THE 30S...SO SOME EMBEDDED THUNDERSTORMS ARE POSSIBLE. RAINFALL AMOUNTS WILL BE ENHANCED WHERE/IF THUNDERSTORMS DO DEVELOP. THE GOOD NEWS IS THE FRONT IS FORECAST TO BE FAIRLY PROGRESSIVE AND MOVE THROUGH THE AREA OVERNIGHT AND BE OFFSHORE BY SUNRISE SATURDAY WHICH SHOULD LIMIT ANY FLOOD POTENTIAL TO THE URBAN/POOR DRAINAGE TYPE. SOME LINGERING LIGHT RAIN IS POSSIBLE, MAINLY TOWARD THE COAST, EARLY SATURDAY AS THE FRONT PUSHES FARTHER AWAY FROM THE AREA. BEHIND THE FRONT, A GUSTY WESTERLY FLOW WILL DEVELOP. HIGH PRESSURE WILL BUILD ACROSS THE NORTHEAST SATURDAY NIGHT INTO SUNDAY WHICH WILL PROVIDE DRY WEATHER FOR THE REGION. THE HIGH TRIES TO RETREAT NORTHEASTWARD ON MONDAY, BUT WE MAY STILL REMAIN UNDER THE GRASP OF THE FAR SOUTHERN EXTEND OF THE HIGH. THICKNESSES FAIL TO RECOVER SUNDAY INTO MONDAY, AND WITH AN EASTERLY FLOW ACROSS THE AREA TEMPERATURES ARE FORECAST TO BE A FEW DEGREES BELOW NORMAL. AS THE HIGH RETREATS MONDAY INTO MONDAY NIGHT, A WEAK SURFACE TROUGH IS FORECAST TO DEVELOP OFFSHORE OF THE SOUTHEAST STATES AND BEGIN NOSING ITS WAY TOWARD OUR AREA. WITH A COUPLE OF WEAK SHORT WAVES MOVING ACROSS THE AREA, WE COULD HAVE SOME PRECIPITATION DEVELOP AND MOVE ACROSS THE AREA. SCATTERED SHOWERS COULD CONTINUE INTO TUESDAY WITH A COUPLE OF WEAK SHORT WAVES EMBEDDED IN THE SOUTHWEST FLOW ALOFT. ANOTHER COLD FRONT IS FORECAST TO AFFECT THE AREA SOMETIME LATE WEDNESDAY INTO THURSDAY. THIS COULD BRING ANOTHER ROUND OF MODERATE TO HEAVY RAINFALL TO THE AREA. && .AVIATION /13Z THURSDAY THROUGH MONDAY/... THE FOLLOWING DISCUSSION IS FOR KPHL, KPNE, KTTN, KABE, KRDG, KILG, KMIV, KACY AND SURROUNDING AREAS. TODAY...AREAS OF IFR CIGS POSSIBLY TO SPREAD INTO PHL/ILG MID OR LATE MORNING. CIGS WILL BE AN OCNL PBLM TODAY AND CERTAINLY NOT AN ALL VFR DAY. ESE WIND INCREASING WITH GUSTS THIS AFTN TO NEAR 20 KT. TONIGHT...IFR CIGS BECOMING WIDESPREAD WITH VSBY LOWERING TO LESS THAN A MILE LATER AT NIGHT WITH A SMALL CHC OF LIFR CONDS IN PATCHY DENSE FOG...ESPECIALLY E PA AND COASTAL S NJ. THIS WITH SREF CIG VSBY PROB SUPPORT FROM THEN 09Z/18 SREF. OUTLOOK... FRIDAY...MVFR/IFR CONDITIONS POSSIBLE EARLY WITH POSSIBLE VFR LATE. DRIZZLE/FOG EARLY AND CHANCE OF RAIN/THUNDERSTORMS BY AFTERNOON. GUSTY SOUTH WINDS AROUND 25-30 KNOTS POSSIBLE. FRIDAY NIGHT...MVFR/IFR CONDITIONS EXPECTED WITH A PERIOD OF HEAVY RAIN AND THUNDERSTORMS POSSIBLE. SATURDAY...LINGERING SHOWERS AND POSSIBLE MVFR/IFR EARLY, MAINLY TOWARD THE COAST. IMPROVING TO VFR DURING THE DAY. GUSTY WEST WINDS 20-25 KNOTS. SATURDAY NIGHT-SUNDAY NIGHT...VFR CONDITIONS EXPECTED. MONDAY...MOSTLY VFR, POSSIBLE NEAR MVFR WITH SHOWERS. && .MARINE... A WARM FRONT WILL MOVE BY TO THE N TODAY AND SELY FLOW WILL BECOME SLY AND INCREASE WELL INTO TONIGHT. THIS WILL CAUSE SEAS TO INCREASE AS WELL. THEREFORE, A SCA IS BEING RAISED BEGINNING AT 19/00Z. AT THIS POINT, IT IS ONLY FOR THE OCEAN, BUT MAY NEED TO BE EXPANDED FOR AT LEAST THE LOWER PORTION OF DEL BAY, BUT CONFIDENCE IS LOWER HERE. OUTLOOK... A STRONG COLD FRONT WILL MOVE ACROSS THE WATERS FRIDAY NIGHT INTO SATURDAY. WINDS ARE EXPECTED TO INCREASE AHEAD OF THE FRONT, AND COULD APPROACH GALE FORCE. THERE IS A STRONG FLOW ABOVE THE SURFACE, BUT IT MAY HAVE TROUBLE MIXING DOWN IN THE SOUTHERLY FLOW. FOR NOW, A SMALL CRAFT ADVISORY WILL BE IN EFFECT, AND WE WILL LET THE NEXT SHIFT SEE IF A GALE WARNING WILL BE NEEDED. ADVISORY LEVELS WINDS AND/OR SEAS WILL LIKELY CONTINUE INTO A PART OF SATURDAY. AS HIGH PRESSURE BUILDS ACROSS THE NORTHEAST THEN OFFSHORE EARLY NEXT WEEK, AN EASTERLY FLOW WILL DEVELOP ACROSS THE AREA. WINDS COULD CONTINUE TO GUST NEAR ADVISORY LEVELS THROUGH MONDAY, AND SEAS COULD REMAIN AROUND 4-5 FEET OR HIGHER WITH THE EASTERLY FETCH. && .PHI WATCHES/WARNINGS/ADVISORIES... PA...NONE. NJ...NONE. DE...NONE. MD...NONE. MARINE...SMALL CRAFT ADVISORY FROM 8 PM THIS EVENING TO 8 PM EDT FRIDAY FOR ANZ450>455. && $$ SYNOPSIS...ROBERTSON/DRAG 854 NEAR TERM...DRAG/NIERENBERG 854 SHORT TERM...DRAG/NIERENBERG 854 LONG TERM...ROBERTSON AVIATION...DRAG/ROBERTSON 854 MARINE...DRAG/NIERENBERG/ROBERTSON 854
AREA FORECAST DISCUSSION
NWS WAKEFIELD VA
139 PM EDT THU APR 18 2013 .SYNOPSIS... A WEAK FRONT WILL SLOWLY LIFT BACK NORTH AS A WARM FRONT LATER TODAY...AS HIGH PRESSURE SLIDES OFF THE NEW ENGLAND COAST. A STRONG COLD FRONT WILL APPROACH FROM THE WEST ON FRIDAY AND MOVE ACROSS THE MID ATLANTIC FRIDAY NIGHT. HIGH PRESSURE BUILDS ACROSS THE NORTHEAST OVER THE WEEKEND AS A FRONTAL BOUNDARY REMAINS STALLED OFF THE SOUTHEAST COAST. && .NEAR TERM /THROUGH TONIGHT/... THE LATEST SURFACE ANALYSIS INDICATES A 1032MB HIGH CENTERED OVER THE MARITIME PROVINCES OF CANADA...WITH A COMPLEX AREA OF LOW PRESSURE AND ASSOCIATED COLD FRONT LIFTING THROUGH THE MID- MISSISSIPPI VALLEY. AN OLD WEAK FRONTAL BOUNDARY HAS NOW LARGELY LIFTED N OF THE AREA WITH ONLY A FEW LINGERING SHOWERS CLIPPING NW DORCHESTER COUNTY. THROUGH THE LATE MORNING AND AFTERNOON...THE REGION WILL BE UNDER THE INFLUENCE OF STRENGTHENING SW FLOW ALOFT AND S/SE FLOW AT THE SURFACE AROUND THE WESTERN PERIPHERY OF THE HIGH. THIS WILL HELP SCOUR OUT LOW CLOUDS AND SHOULD KEEP THE AFTN MAINLY DRY UNDER A PARTLY SUNNY SKY. LOW LEVEL THICKNESSES SUGGEST HIGHS WILL REMAIN ABOVE AVG...INTO THE LWR 80S SOUTH CENTRAL VA...AROUND 80 MUCH OF CENTRAL VA...AND IN THE MID- UPPER 70S ACRS THE NORTH AND CLOSER TO THE COAST. (LOCALLY IN THE 60S ON THE COAST OF THE EASTERN SHORE). ONE EXCEPTION TO THIS WILL BE THE IMMEDIATE ATLANTIC COAST OF THE EASTERN SHORE FROM OCEAN CITY TO CHINCOTEAUGE. THE LATEST GUIDANCE SUGGESTS THAT THE FRONT DOES NOT CLEAR THE IMMEDIATE COAST AS THERE WILL NOT BE ENOUGH GRADIENT TO OVERCOME THE INFLUENCE OF SSTS AROUND 50F. THIS WILL ALLOW LOW-LEVEL EASTERLY FLOW TO CONTINUE ALONG WITH STRATUS AND FOG LINGERING THROUGH MUCH OF THE DAY. THIS SHOULD HOLD HIGHS IN THE UPPER 50S TO AROUND 60. FOR TONIGHT...CAN`T RULE OUT AN ISOLATED SHRA/TSRA ACRS THE PIEDMONT BUT WILL KEEP FCST DRY FOR NOW WITH LITTLE TO TRIGGER FOR PRECIP. MODELS BEGIN TO SHOW INCREASING LOW LEVEL MOISTURE AFTER MIDNIGHT SO MOST AREAS BECOME CLOUDY PRIOR TO DAYBREAK FRI. VERY WARM UNDER STRENGTHENING SOUTHERLY FLOW AND HAVE GENLY GONE ON THE WARM SIDE OF GUIDANCE WITH LOWS IN THE LWR 60S FOR MUCH OF THE CWA...LOCALLY IN THE 50S NEAR THE COAST. DUE TO WIND/MIXING THINK FOG WILL GENLY NOT BE AN ISSUE DESPITE THE INCREASE IN LOW LEVEL MOISTURE...EXPECT IT TO BE MORE OF A STRATUS EVENT. && .SHORT TERM /FRIDAY THROUGH SATURDAY/... OVERALL THERE IS LITTLE CHANGE WITH RESPECT TO TIMING OF THE COLD FRONT LATE FRI/FRI NIGHT. MODELS CONTINUE TO SHOW SOME LIGHT QPF AMOUNTS WELL OUT AHEAD OF THE FRONT EARLY FRI MORNING ACRS SE VA/NE NC...SO RETAIN A LOW CHC POP IN THESE AREAS FRI MORNING. THIS SHOULD NOT AMOUNT TO MUCH HOWEVER AS MODEL SOUNDINGS ARE VERY DRY ALOFT UNDER STRONG SW FLOW. OTHER THAN A FEW SHRA...DO NOT EXPECT TO HAVE MUCH ON THE RADAR THROUGH ABOUT 18-21Z OR SO FRI AFTN. THIS WILL ALLOW FOR PARTIAL CLEARING LATE IN THE MORNING ALONG WITH BREEZY SSW FLOW. HIGHS SHOULD AGAIN REACH INTO THE UPPER 70S TO LOWER 80S FOR MOST OF THE REGION. NAM/GFS DIFFER SOMEWHAT IN THEIR DEPICTION OF THE FORCING (WITH THE NAM BEING DEEPER THROUGH THE COLUMN THAN THE GFS). TIMING IS QUITE SIMILAR HOWEVER...PROGGED TO ARRIVE IN THE FAR WESTERN PORTION OF THE AREA LATE FRIDAY AFTERNOON...INTO CENTRAL VA BETWEEN 21Z AND 00Z...AND TO THE COAST AFTER 03Z. THE NAM IS ALSO STILL A BIT MORE GENEROUS WITH INSTABILITY THAN THE GFS WITH VALUES ON THE ORDER OF ~750-1000 J/KG OVER S-CENTRAL VA AND INTERIOR NE NC ALONG WITH 40-50KT OF DEEP LAYER SHEAR. IF THIS WERE TO VERIFY...THUNDERSTORMS CAPABLE OF PRODUCING STRONG WIND GUSTS ARE POSSIBLE. HOWEVER...THE THERMODYNAMIC PROFILE SHOULD QUICKLY STABILIZE LATER IN THE EVENING AS THE FRONT BECOMES MORE ANA-FRONTAL. ALSO...THE HIGHEST SHEAR VALUES ARE AFTER THIS STABILIZING EFFECT DUE TO THE UPPER JET AND STRONGER HEIGHT FALLS AT H5 LAGGING BEHIND BY SEVERAL HUNDRED MILES. OVERALL...THIS SETUP SUGGEST THE POTENTIAL FOR SOME LOCALLY STRONG WIND GUSTS...BUT NOT A SIGNIFICANT SEVERE OUTBREAK. SPC SEEMS TO CONCUR AND AREA STILL IS ONLY IN A "SEE TEXT" RATHER THAN A SLIGHT RISK. THE UPPER JET DOES BECOME FAVORABLY SETUP WITH LOCAL AREA IN RRQ FORCING FOR SEVERAL HRS OF MODERATE TO SOMEWHAT HEAVY RAIN THROUGH THE OVERNIGHT HRS..AND PRECIPITABLE WATER VALUES CLIMB TO 1.50 TO 1.70". MOST OF THE CWA CAN EXPECT TO RECEIVE QPF AMOUNTS OF 0.75 TO 1.25"...WITH HIGHER AMOUNTS MOST LIKELY OCCURRING ACRS SE VA/NE NC WHERE RAIN WILL CONTINUE THROUGH SOME OF THE DAY ON SATURDAY (AND LOCALLY HIGHER AMOUNTS WILL BE POSSIBLE DUE TO THE CONVECTIVE NATURE OF THE PRECIP INITIALLY). STILL DO NOT SEE THIS EVENT LEADING TO ANYTHING MORE THAN MINOR/NUISANCE FLOODING IN POOR DRAINAGE AREAS AS BULK OF THE BEST FORCING OCCURS POST FRONTAL WITH TEMPERATURES IN THE 50S AND 60S...AS WELL AS FACT THAT APRIL FLASH FLOOD EVENTS ARE RARE IN THE AKQ CWA. LOWS RANGE FROM THE UPPER 40S NW TO THE MID 50S SE. BULK OF PRECIP ENDS ACRS THE NW AFTER 06Z...BUT PERSISTS WELL PAST 12Z FOR FAR SE SECTIONS. HIGH PRESSURE BUILDS IN FORM THE NORTHWEST SATURDAY WITH DRYING COMMENCING FROM NW TO SE. HIGH TEMPERATURES WILL BE MUCH COOLER AND WILL GENLY BE IN THE LOWER TO MID 60S (NOT A LOT OF DOWNSLOPING TO OFFSET CAA). HIGHS ONLY IN THE LOW 60S (WITH AFTN TEMPS IN THE UPPER 50S) POSSIBLE OVER SE COASTAL AREAS AS CLOUD COVER AND COOL ONSHORE NNE FLOW LINGERS INTO THE AFTERNOON. && .LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/... GOING WITH A COMBINATION OF THE 12Z GFS AND 12Z ECMWF FOR THE EXTENDED PERIOD...BUT LEANING TWD THE ECMWF IN THE FIRST PART OF THE PERIOD...THEN LEANING TWD THE GFS FOR END OF THE PERIOD. DRY WX FOR SAT NGT INTO SUN NGT...AS HI PRES BLDS ACRS THE GRT LKS AND INTO NEW ENGLAND. THIS WILL MAKE FOR A CHILLY DAY SUNDAY W/ HIGHS AT LEAST 10 DEGREES BELOW AVG...ONLY LOWER 60S INLAND WITH UPPER 50S NEAR THE COAST DUE TO COOL NE FLOW). THE CNTR OF THAT HI WILL MOVE INTO THE NRN ATLC MON THRU TUE...AS AN INVERTED TROF DEVELOPS ALNG THE SE/MID ATLC CST WITH WEAK LO PRES FORMING ALNG IT AND MOVNG NNE UP THE CST. THIS WILL PRODUCE A MOIST ONSHORE FLO...WITH A SLGT CHC OR CHC OF SHOWERS OVR THE REGION. A COLD FRONT WILL THEN APPROACH FM THE W LATE WED...WITH AT LEAST A SLGT CHC FOR MORE SHOWERS. MIN TEMPS WILL RANGE FM THE UPR 30S TO UPR 40S SUN AND MON MORNGS...IN THE LWR 40S TO LWR 50S TUE MORNG...AND IN THE UPR 40S TO MID 50S WED MORNG. && .AVIATION /18Z THURSDAY THROUGH TUESDAY/... WARM FRONT HAS MOVED NORTH OF THE AREA. GENERALLY SOUTHERLY FLOW ACROSS THE AREA AND THIS WILL CONTINUE THROUGH THE NIGHT. CAN SEE FOG STILL ALONG THE MD COAST AND MODELS ALL EXPAND THAT WEST WITH TIME ACROSS SBY AFTER SUNSET. TIMED SBY TO START COMING DOWN BY 03Z AND CONTINUE TO BE IFR THROUGH 14Z. THINK ENOUGH MIXING WILL BE OCCURRING BY THEN WITH THE SUN UP TO GET RID OF LOW CLOUDS. BUFKIT SHOWS THESE CLOUDS ON BOTH THE RAP AND NAM MODELS TO BE QUITE THIN. THE STATISTICAL GUIDANCE DOES NOT CLEAR IT OUT BUT IT HAS BEEN HOLDING ON TO THE LOW CEILING TOO LONG THIS MORNING. ALSO THE MODELS KEEP TRYING TO BRING THE OTHER TAF SITES DOWN TO IFR AFTER MIDNIGHT BUT WITH 10 KTS OF WINDS AND ALL MODELS AGREEING THAT THE MOISTURE IS CONFINED BELOW 925 MB THINK THE MIXING WILL KEEP THE LOW CLOUDS AWAY OVERNIGHT. THEN ON FRIDAY WITH STRONG COLD FRONT APPROACHING WILL HAVE BKN CU DEVELOP ACROSS THE AREA DURING THE MORNING. THE PRECIPITATION WITH THE FRONT WILL REACH RIC NEAR 00Z AND THERE WILL BE SOME THUNDERSTORMS ALONG THE LEADING EDGE OF THE FRONT. MORE RAIN WILL CONTINUE FOR SEVERAL HOURS BEHIND THE FRONT. THIS WILL BRING IFR CONDITIONS TO ALL TAF SITES FOR FRIDAY NIGHT. CONDITIONS WILL IMPROVE RAPIDLY ON SAT DURING THE MORNING WITH VFR CONDITIONS EXPECTED ALL AREAS BY AFTERNOON AND CONTINUING INTO SUNDAY. COULD SEE SOME MVFR OR IFR CONDITIONS RETURN BY MONDAY WITH BEST CHANCES NEAR THE COAST. && .MARINE... STARTED SCA FOR THE BAY AT 4PM. MANY OF THE HIGH RES MODELS INDICATE SE/S WINDS INCREASING TO NEAR 20 KNOTS TOWARD EVENING AND CONTINUING UNTIL AROUND OR SHORTLY AFTER MIDNIGHT. A LULL IN THE WIND WILL THEN OCCUR UNTIL LATE FRIDAY MORNING...WHEN S WINDS INCREASE ONCE AGAIN. KEPT SCA GOING THROUGH LATE FRIDAY NIGHT SINCE THE LULL SHOULD BE LESS THAN 12 HOURS. PREVIOUS DISCUSSION... A WEAK FRNT WILL SLOWLY LIFT N TDY AS A WARM FRNT...WITH 10-15 KT E WINDS BCMG SE 15 KT OR LESS THIS AFTN. SOUTHERLY FLOW FURTHER INCREASES LATE TNGT INTO FRI MRNG AS THE PRES GRADIENT TIGHTENS UP AHEAD OF AN APPROACHING COLD FRNT. SCA CONDITIONS WILL BE LIKELY BY THU NGT/FRI OVER THE WTRS...AND PERHAPS CONTINUING INTO ERLY SAT. HAVE GONE AHEAD AND HOISTED A SCA OVER THE COASTAL WATERS FOR SEAS AOA 5 FT AND WINDS UP TO 25 KT PSBL. ALSO ISSUED A SCA FOR THE BAY/SOUND FRI MIDDAY THRU EVENG WITH 20-25 KT WINDS EXPECTED AHEAD OF THE FRNT. WINDS BEHIND THE FRNT (FROPA IS FRI NGT) MAY BE MARGINAL OR JUST BLO SCA THRESHOLDS...SO WILL END THE HEADLINE WITH THE FROPA FOR NOW. ALSO HELD OFF WITH THE RIVERS FOR NOW WITH NOT ENUF CONFIDENCE IN A LATE 3RD PERIOD SCA THERE. EXPECT A LULL IN WINDS DURING SAT AFTN...FOLLOWED BY A SURGE OF COLDER AIR ON NE WINDS SAT NGT THRU SUN...AS STRONG SFC HI PRES BLDS OVER THE GREAT LAKES. && .AKQ WATCHES/WARNINGS/ADVISORIES... MD...NONE. NC...NONE. VA...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 4 AM EDT SATURDAY FOR ANZ630>632- 634. SMALL CRAFT ADVISORY FROM NOON FRIDAY TO 4 AM EDT SATURDAY FOR ANZ633. SMALL CRAFT ADVISORY FROM 4 AM FRIDAY TO 7 AM EDT SATURDAY FOR ANZ654. SMALL CRAFT ADVISORY FROM 10 AM FRIDAY TO 7 AM EDT SATURDAY FOR ANZ656-658. SMALL CRAFT ADVISORY FROM 10 PM THIS EVENING TO 7 AM EDT SATURDAY FOR ANZ650-652. && $$ SYNOPSIS...LKB NEAR TERM...AJZ/LKB SHORT TERM...AJZ/LKB LONG TERM...TMG AVIATION...JAB MARINE...MAS/LSA
AREA FORECAST DISCUSSION
NWS TWIN CITIES/CHANHASSEN MN
250 PM CDT THU APR 18 2013 .SHORT TERM...(THIS EVENING THROUGH FRIDAY) ISSUED AT 249 PM CDT THU APR 18 2013 IMPRESSIVE DEFORMATION SNOW EVENT WELL UNDERWAY...WITH STRONG FGEN NOTED IN THE H8-H5 LAYER. SEEING CONVECTIVE ELEMENTS COMING UP OUT OF IOWA...WHICH IS AN INDICATION OF THE INSTABILITY PRESENT...WITH SEVERAL HEAVY BANDS OF SNOW NOTED ON RADAR AS A RESULT. HAVE GOTTEN REPORTS OF AROUND 2 INCHES PER HOUR OUT IN WRN MN THIS AFTERNOON...AND EXPECT THESE SORTS OF RATES TO CONTINUE THROUGH THE AFTERNOON. THROUGH TONIGHT...FOLLOWED THE RAP FAIRLY CLOSELY FOR FORECAST UPDATES TODAY...AS IT HAS HAD A PRETTY GOOD HANDLE ON HOW THINGS HAVE UNFOLDED ALL DAY. AS A RESULT...BOOSTED SNOW TOTALS SOME WITHIN THE HEART OF THE BAND FROM REDWOOD FALLS UP THROUGH ST. CLOUD...WITH 6 INCH AMOUNTS CREEPING EAST TO BE ACROSS THE EAST END OF THE WARNING COUNTIES NOW...WITH SNOW TOTAL AT MINNEAPOLIS INCREASED FROM AROUND 3 INCHES TO 6 INCHES. IF THE RAP WERE TO BE BELIEVED /WHICH BASED ON REPORTS SEEN SO FAR...DO NOT SEE WHY IT CAN NOT BE/...THEN WE WILL LIKELY END UP WITH A BAND OF 10 TO 12 INCHES FROM GRANITE FALLS OVER TO NEW ULM AND UP TO LONG PRAIRIE OVER TO MORA. WITH UPDATES MADE TO FORECAST TODAY...DID ADD TODD COUNTY TO THE WARNING AND COULD HAVE VERY EASILY ADDED STEVENS AND DOUGLAS COUNTIES OUT WEST...ALONG WITH ANOTHER ROW OF COUNTIES TO THE EAST OF THE WARNING THAT WOULD INCLUDE THE REST OF THE TWIN CITIES. IN FACT...AS OF THE WRITING OF THIS...THINKING WE WILL GO AHEAD AND EXPAND THE WARNING EAST AND WEST WHEN DONE WITH THIS AFD TO INCLUDE ALL OF THE TWIN CITIES METRO AREA. HEAVY SNOW WILL START LETTING UP AFTER 21Z SW OF THE MN RIVER...BETWEEN 0Z AND 3Z ALONG I-94 FROM THE TWIN CITIES UP THROUGH ST. CLOUD...WITH HEAVY SNOW PULLING OUT OF THE NRN CWA SHORTLY AFTER 06Z. LIGHT SNOW WILL CONTINUE THROUGH TONIGHT...WITH LIGHT SNOW SHOWERS CONTINUING THROUGH THE DAY ACROSS WRN WI ON FRIDAY...THOUGH MAJORITY OF ACCUMULATIONS WILL BE COMING NOW THROUGH 12Z FRIDAY. FOR FRIDAY...ANY ADDITIONAL ACCUMULATIONS WILL BE UNDER AN INCH. AT 230 PM...THE RAIN/SNOW LINE WAS LOCATED NEAR AN ALBERT LEA THROUGH RICE LAKE LINE...AND AGAIN GENERALLY FOLLOWED THE RAP...WITH ALL SNOW FINALLY BREAKING OUT IN THE EAU CLAIRE AREA AROUND 3Z. AS FOR TEMPERATURES...CLOUD COVER AND NW WINDS WILL RESULT IN FAIRLY STEADY TEMPERATURES THROUGH FRIDAY...WITH LOWS TONIGHT FALLING BACK INTO THE UPPER 20S/LOWER 30S WHILE HIGHS ON FRIDAY STAY MIRED IN THE 30S...OR ABOUT 20 DEGREES BELOW NORMAL. .LONG TERM...(FRIDAY THROUGH WEDNESDAY) ISSUED AT 441 AM CDT THU APR 18 2013 SNOW WILL TAPER OFF ACROSS THE EASTERN FORECAST AREA ON FRIDAY AS THE NEARLY STACKED LOW MOVES ACROSS THE GREAT LAKES. ADDITIONAL SNOWFALL ACCUMS ON FRIDAY SHOULD GENERALLY VARY FROM A DUSTING /TWIN CITIES/ TO AROUND ONE INCH /LADYSMITH TO EAU CLAIRE/. IT WILL FEEL QUITE WINTRY ON FRIDAY...AS TEMPERATURES ONLY REACH THE MID 30S AT THEIR WARMEST...AND COMBINE WITH BRISK NORTHWEST WINDS OF 15 TO 25 MPH. SURFACE HIGH PRESSURE MAKES AN APPEARANCE FOR SATURDAY...ACCOMPANIED BY COOL AND DRY CONDITIONS. SATURDAY MORNING LOWS WILL LIKELY RANGE BETWEEN 15 AND 20 DEGREES BELOW NORMAL...AS CLEARING SKIES AND LIGHT WINDS ALLOW READINGS TO TUMBLE INTO THE TEENS ACROSS THE MAJORITY OF THE FORECAST AREA. SATURDAY HIGH TEMPERATURES WILL FOLLOW SUIT WITH RESPECT TO BEING ON THE COLD SIDE OF NORMAL...AND ONLY REACH THE UPPER 30S AND LOWER 40S. THE RESPITE FROM PRECIPITATION WILL BE BRIEF...AS THE NEXT TROUGH ARRIVES LATE IN THE WEEKEND. ISENTROPIC LIFT FROM 290-305K BLOSSOMS ACROSS THE FORECAST AREA BETWEEN 06Z AND 12Z SUNDAY...WHEN 50-60 POPS HAVE BEEN INCLUDED. THE ASSOCIATED COLD FRONT MOVES ACROSS THE FORECAST AREA ON SUNDAY NIGHT AND MONDAY...AND THEN STALLS JUST SOUTHEAST OF THE FORECAST AREA THROUGH TUESDAY. THIS WILL YIELD PROLONGED 20-30 POPS ACROSS THE SOUTHERN/EASTERN PARTS OF THE FORECAST AREA INTO WEDNESDAY AS THE BAROCLINIC ZONE LOITERS NEARBY...AND INTERACTS WITH PERIODIC WEAK MID LEVEL SHORTWAVES TRAVELING THROUGH THE WEST/SOUTHWEST FLOW. TEMPERATURES NEXT WEEK WILL REMAIN COOLER THAN NORMAL...WITH HIGHS/LOWS IN THE 40S/30S RESPECTIVELY. THERE IS...HOWEVER...INDICATION OF MODERATING TEMPERATURES LATE NEXT WEEK AS THE WESTERN RIDGE BUILDS TOWARD THE CENTRAL CONUS. HIGHS IN THE LOW/MID 50S APPEAR ATTAINABLE BY THURSDAY. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON) ISSUED AT 138 PM CDT THU APR 18 2013 BAND OF HEAVY SNOW SETTING UP ACROSS MN THIS AFTERNOON. SEEING CONVECTIVE ELEMENTS COMING UP OUT OF IA INTO THE MN SNOW BAND...WHICH FURTHER SUPPORTS THE IDEA OF HEAVY SNOW CONTINUING THROUGH THE AFTERNOON. THE RAP HAS DONE A GREAT JOB IN HANDLING THE EVOLUTION OF THE SNOW SO FAR...SO FOLLOWED IT CLOSELY FOR TIMING SNOW THROUGH TERMINALS. 1/4SM TO 1SM VIS IN SNOW WILL BE COMMON THROUGH 00Z AT ALL BUT EAU. FOR EAU...NAM CHANGES TO SNOW AT 1Z WITH THE RAP CHANGING OVER AT 4Z. EXPECTING AMOUNTS NEAR 10 INCHES AT RWF/STC...6 INCHES AT MSP/RNH/AXN...WITH LESS THAN 3 INCHES AT EAU. FOR THE IMPROVEMENT...MAY BE A LITTLE SLOW IN IMPROVING CONDITION TONIGHT/FRI MORNING...BUT LATER TAFS CAN IMPROVE THAT TIMING. FOR WINDS...DID BUMP THEM DOWN THROUGH THE AFTERNOON AS HEAVY SNOW APPEARS TO BE DAMPENING WINDS SOME...WITH SPEEDS EXPECTED TO INCREASE TONIGHT AS SNOW LETS UP. KMSP... GIVEN RECENT RADAR TRENDS AND RAP FORECASTS...CONFIDENCE HIGH IN HEAVY SNOW IMPACTING MSP BETWEEN 20Z AND 03Z...WITH A GRADUAL DECREASE IN INTENSITY BETWEEN 03Z AND 06Z. HAVE INCREASED EXPECTED SNOWFALL AMOUNTS AS A RESULT UP INTO THE 6 INCH RANGE. CONFIDENCE DECREASES SOME WITH RATE OF IMPROVEMENT TONIGHT...THOUGH CONFIDENCE IS HIGH IN CIGS REMAINING BELOW 1700 FT. DURING THE MORNING INTO THE AFTERNOON...WILL SEE CIGS IMPROVE ABOVE 1700 FT. FOR WINDS...DIMINISHED SPEEDS COMPARED TO LAMP WHILE HEAVY SNOW IS FALLING...BUT INCREASED SPEEDS CLOSER TO LAMP GUIDANCE AS SNOW BEGINS TO DIMINISH TONIGHT. /OUTLOOK FOR KMSP/ SAT...VFR WITH MVFR AND -RA POSSIBLE LATE. WINDS SE AT 10G15KTS. SUN...MVFR WITH IFR AND -RA POSSIBLE. WINDS S AT 10G15KTS. MON...MVFR OR LOWER WITH -RA POSSIBLE. WINDS BCMG NNW 10G20KTS. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...WINTER WEATHER ADVISORY UNTIL 1 PM CDT FRIDAY FOR MNZ062-063-069- 070-076>078-082>085-091-092. WINTER WEATHER ADVISORY UNTIL 10 AM CDT FRIDAY FOR MNZ041-047. WINTER STORM WARNING UNTIL 10 AM CDT FRIDAY FOR MNZ042>045- 048>061-064>068-073>075. WI...WINTER WEATHER ADVISORY UNTIL 1 PM CDT FRIDAY FOR WIZ014>016- 023>025. && $$ SHORT TERM...MPG LONG TERM...LS AVIATION...MPG
AREA FORECAST DISCUSSION
NWS TWIN CITIES/CHANHASSEN MN
138 PM CDT THU APR 18 2013 .UPDATE... 18Z AVIATION DISCUSSION ADDED BELOW. && .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 441 AM CDT THU APR 18 2013 TODAY AND TONIGHT...EARLY MORNING WATER VAPOR IMAGERY TOGETHER WITH 500MB HEIGHTS AND WINDS SHOWED THE POSITIVELY TILTED LONGWAVE TROUGH CENTERED OVER THE HIGH PLAINS WITH DEEP CONVECTION BREAKING OUT DOWNSTREAM OF THE TROUGH AXIS FROM CENTRAL TEXAS UP THROUGH THE GREAT LAKES REGION. A DRY SLOT ROUNDING THE BASE OF THE TROUGH WAS EVIDENT OVER THE TEXAS/OKLAHOMA PANHANDLES UP THROUGH EASTERN NEBRASKA. THE SURFACE LOW WAS CENTERED IN NORTHEAST MISSOURI...AND THIS LOW IS FORECAST TO PROPAGATE INTO SOUTHEAST WISCONSIN AND DEEPEN AS 16-20M/HR 500MB HEIGHTFALLS ASSOCIATED WITH THE MAIN SHORTWAVE OVERSPREAD THE REGION LATER TODAY. A POWERFUL UPPER LEVEL JET SITS ATOP A DEEP FRONTAL ZONE...AND THE BIG QUESTION FOR THIS FORECAST PERIOD IS WHERE THIS FRONT WILL BECOME ACTIVE...AND WHAT THE PREDOMINANT PTYPE WILL BE. NORTHWEST TO SOUTHEAST CROSS SECTIONS DEPICT A DEEP AREA OF FRONTOGENETIC FORCING...SO A BAND OF HEAVY SNOW IS IMMINENT LATER TODAY. CURRENTLY EXPECTING THIS BAND TO SET UP FROM REDWOOD FALLS UP THROUGH DULUTH MN...WHERE SNOW IS FORECAST. THE NAM 18.00 BUFR SOUNDINGS MATCHED UP VERY WELL WITH THE MPX RAOB...SO USED THIS TEMPERATURE PROFILE TO DETERMINE PTYPE. HOWEVER...NAM SURFACE TEMPS WERE TOO COOL SO EXPECTING LESS ACCUMULATION THAN THE NAM COBB OUTPUT WOULD SUGGEST...WHICH SHOWS 20/25:1 RATIOS. THE RAIN/SNOW/SLEET LINE WILL ONCE AGAIN STRADDLE THE METRO AREA ALLOWING FOR A WIDE RANGE OF SNOW TOTALS FROM WEST TO EAST. SREF PLUMES SHOW 7 TO 8 INCHES AT KMSP...BUT AFTER REMOVING THE TOP OUTLIERS HAVE MORE LIKE 6 TO 7 INCHES. BASED ON THE FORECAST SOUNDINGS ELEVATED INSTABILITY AND WARMER LOW LEVELS FEEL THAT THESE ARE STILL OVERDONE AND WILL LOSE SOME SNOW ACCUMULATION TO CONVECTIVE GRAUPEL...SO HAVE AROUND 3 INCHES OF SNOW IN THE EAST METRO...WITH UP TO 7 IN THE WEST. THE BULK OF THE PRECIP WILL FALL THIS AFTERNOON...MAKING THE COMMUTE DIFFICULT. WILL LIKELY SEE SNOW RATES OF 1-2 INCHES PER HOUR WITHIN THE HEAVY BAND...BUT ANTICIPATING THIS WILL BE JUST WEST OF THE METRO AS INDICATED BY THE HOPWRF. .LONG TERM...(FRIDAY THROUGH WEDNESDAY) ISSUED AT 441 AM CDT THU APR 18 2013 SNOW WILL TAPER OFF ACROSS THE EASTERN FORECAST AREA ON FRIDAY AS THE NEARLY STACKED LOW MOVES ACROSS THE GREAT LAKES. ADDITIONAL SNOWFALL ACCUMS ON FRIDAY SHOULD GENERALLY VARY FROM A DUSTING /TWIN CITIES/ TO AROUND ONE INCH /LADYSMITH TO EAU CLAIRE/. IT WILL FEEL QUITE WINTRY ON FRIDAY...AS TEMPERATURES ONLY REACH THE MID 30S AT THEIR WARMEST...AND COMBINE WITH BRISK NORTHWEST WINDS OF 15 TO 25 MPH. SURFACE HIGH PRESSURE MAKES AN APPEARANCE FOR SATURDAY...ACCOMPANIED BY COOL AND DRY CONDITIONS. SATURDAY MORNING LOWS WILL LIKELY RANGE BETWEEN 15 AND 20 DEGREES BELOW NORMAL...AS CLEARING SKIES AND LIGHT WINDS ALLOW READINGS TO TUMBLE INTO THE TEENS ACROSS THE MAJORITY OF THE FORECAST AREA. SATURDAY HIGH TEMPERATURES WILL FOLLOW SUIT WITH RESPECT TO BEING ON THE COLD SIDE OF NORMAL...AND ONLY REACH THE UPPER 30S AND LOWER 40S. THE RESPITE FROM PRECIPITATION WILL BE BRIEF...AS THE NEXT TROUGH ARRIVES LATE IN THE WEEKEND. ISENTROPIC LIFT FROM 290-305K BLOSSOMS ACROSS THE FORECAST AREA BETWEEN 06Z AND 12Z SUNDAY...WHEN 50-60 POPS HAVE BEEN INCLUDED. THE ASSOCIATED COLD FRONT MOVES ACROSS THE FORECAST AREA ON SUNDAY NIGHT AND MONDAY...AND THEN STALLS JUST SOUTHEAST OF THE FORECAST AREA THROUGH TUESDAY. THIS WILL YIELD PROLONGED 20-30 POPS ACROSS THE SOUTHERN/EASTERN PARTS OF THE FORECAST AREA INTO WEDNESDAY AS THE BAROCLINIC ZONE LOITERS NEARBY...AND INTERACTS WITH PERIODIC WEAK MID LEVEL SHORTWAVES TRAVELING THROUGH THE WEST/SOUTHWEST FLOW. TEMPERATURES NEXT WEEK WILL REMAIN COOLER THAN NORMAL...WITH HIGHS/LOWS IN THE 40S/30S RESPECTIVELY. THERE IS...HOWEVER...INDICATION OF MODERATING TEMPERATURES LATE NEXT WEEK AS THE WESTERN RIDGE BUILDS TOWARD THE CENTRAL CONUS. HIGHS IN THE LOW/MID 50S APPEAR ATTAINABLE BY THURSDAY. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON) ISSUED AT 138 PM CDT THU APR 18 2013 BAND OF HEAVY SNOW SETTING UP ACROSS MN THIS AFTERNOON. SEEING CONVECTIVE ELEMENTS COMING UP OUT OF IA INTO THE MN SNOW BAND...WHICH FURTHER SUPPORTS THE IDEA OF HEAVY SNOW CONTINUING THROUGH THE AFTERNOON. THE RAP HAS DONE A GREAT JOB IN HANDLING THE EVOLUTION OF THE SNOW SO FAR...SO FOLLOWED IT CLOSELY FOR TIMING SNOW THROUGH TERMINALS. 1/4SM TO 1SM VIS IN SNOW WILL BE COMMON THROUGH 00Z AT ALL BUT EAU. FOR EAU...NAM CHANGES TO SNOW AT 1Z WITH THE RAP CHANGING OVER AT 4Z. EXPECTING AMOUNTS NEAR 10 INCHES AT RWF/STC...6 INCHES AT MSP/RNH/AXN...WITH LESS THAN 3 INCHES AT EAU. FOR THE IMPROVEMENT...MAY BE A LITTLE SLOW IN IMPROVING CONDITION TONIGHT/FRI MORNING...BUT LATER TAFS CAN IMPROVE THAT TIMING. FOR WINDS...DID BUMP THEM DOWN THROUGH THE AFTERNOON AS HEAVY SNOW APPEARS TO BE DAPPENING WINDS SOME...WITH SPEEDS EXPECTED TO INCREASE TONIGHT AS SNOW LETS UP. KMSP... GIVEN RECENT RADAR TRENDS AND RAP FORECASTS...CONFIDENCE HIGH IN HEAVY SNOW IMPACTING MSP BETWEEN 20Z AND 03Z...WITH A GRADUAL DECREASE IN INTENSITY BETWEEN 03Z AND 06Z. HAVE INCREASED EXPECTED SNOWFALL AMOUNTS AS A RESULT UP INTO THE 6 INCH RANGE. CONFIDENCE DECREASES SOME WITH RATE OF IMPROVEMENT TONIGHT...THOUGH CONFIDENCE IS HIGH IN CIGS REMAINING BELOW 1700 FT. DURING THE MORNING INTO THE AFTERNOON...WILL SEE CIGS IMPROVE ABOVE 1700 FT. FOR WINDS...DIMINISHED SPEEDS COMPARED TO LAMP WHILE HEAVY SNOW IS FALLING...BUT INCREASED SPEEDS CLOSER TO LAMP GUIDANCE AS SNOW BEGINS TO DIMINISH TONIGHT. /OUTLOOK FOR KMSP/ SAT...VFR WITH MVFR AND -RA POSSIBLE LATE. WINDS SE AT 10G15KTS. SUN...MVFR WITH IFR AND -RA POSSIBLE. WINDS S AT 10G15KTS. MON...MVFR OR LOWER WITH -RA POSSIBLE. WINDS BCMG NNW 10G20KTS. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...WINTER WEATHER ADVISORY UNTIL 1 PM CDT FRIDAY FOR MNZ062-063-069- 070-076>078-082>085-091-092. WINTER WEATHER ADVISORY UNTIL 10 AM CDT FRIDAY FOR MNZ041-047. WINTER STORM WARNING UNTIL 10 AM CDT FRIDAY FOR MNZ042>045- 048>061-064>068-073>075. WI...WINTER WEATHER ADVISORY UNTIL 1 PM CDT FRIDAY FOR WIZ014>016- 023>025. && $$ SHORT TERM...JRB LONG TERM...LS AVIATION...MPG
AREA FORECAST DISCUSSION
NWS HASTINGS NE
1222 PM CDT THU APR 18 2013 .UPDATE... ISSUED AT 1045 CDT THU APR 18 2013 AS OF 15Z...WATER VAPOR IMAGERY INDICATES THE MID LEVEL LONGWAVE TROUGH EXTENDING FROM SOUTH CENTRAL CANADA INTO THE CENTRAL AND SOUTHERN PLAINS. AN ENHANCED AREA OF MID LEVEL VORTICITY IS ALSO NOTED OVER PORTIONS OF SOUTH DAKOTA AND NEBRASKA. ENHANCED MID LEVEL MOISTURE IS NOTED EXTENDING FROM THE SOUTHERN PLAINS...NORTHEAST INTO THE OHIO RIVER VALLEY. A MID LEVEL DRY INTRUSION IS EVIDENT FROM NORTH TEXAS INTO EASTERN KANSAS...SOUTHEASTERN NEBRASKA AND PORTIONS OF IOWA. AN AXIS MID LEVEL DEFORMATION...TO THE WEST/NORTHWEST OF THE ENHANCED VORTICITY EMBEDDED WITHIN THE LONGWAVE TROUGH...IS ALSO NOTED EXTENDING FROM EASTERN NORTH DAKOTA INTO PORTIONS OF NEBRASKA. RADAR DATA FROM KUEX INDICATES BANDED SNOWFALL CONTINUING OVER THE EASTERN HALF OF OUR CWA...WITH NOTHING MORE THAN LIGHT SNOW OR SNOW FLURRIES ACROSS OUR EAST. THE SURFACE WIND REMAINS VERY STRONG ACROSS OUR AREA...SUSTAINED FROM THE NORTHWEST AT 15-25KTS WITH HIGHER GUSTS. THE BANDED SNOWFALL ACROSS EASTERN PORTIONS OF OUR CWA APPEARS TO BE A DIRECT RESULT OF THE AFOREMENTIONED MID LEVEL DEFORMATION AXIS CURRENTLY MOVING EAST ACROSS THE REGION. GUIDANCE FROM THE NAM...OPERATIONAL GFS...EC...SREF-MEAN...AND RAP ALL SUGGEST THIS AXIS OF DEFORMATION WILL CONTINUE MOVING EAST TODAY AND AS A RESULT...THE BAND OF SNOWFALL CURRENTLY OVER PORTIONS OF OUR AREA SHOULD ALSO CONTINUE MOVING EAST OUT OF OUR AREA THROUGH THIS AFTERNOON. GIVEN THE CURRENT SATELLITE AND RADAR TRENDS...AS WELL AS MODEL GUIDANCE...WENT AHEAD AND CUT POPS ACROSS WEST/SOUTHWESTERN PORTIONS OF OUR CWA THROUGH THE REMAINDER OF THE DAY. CERTAINLY THERE COULD BE PERIODIC LIGHT SNOW OR SNOW FLURRIES OUT THAT WAY...BUT THE CHANCES OF MEASURABLE PRECIPITATION BEING OBSERVED THROUGH THE REST OF TODAY ARE FAR TOO LOW TO KEEP IN THE FORECAST. WENT AHEAD LINGERED PRECIPITATION OVER OUR EAST/NORTHEAST THROUGH EARLY TO MID-AFTERNOON...WITH DRY CONDITIONS EXPECTED FOR THE MOST PART LATE AFTERNOON. GIVEN THE CURRENT SPEED OF THE SNOW BAND ACROSS OUR AREA AND OBSERVATIONS FROM ACROSS THE AREA...IT SEEMS LOGICAL THAT LOCATIONS WHO OBSERVE SNOWFALL UNDERNEATH THE BAND COULD PICKUP AN ADDITIONAL INCH OF SNOWFALL THIS MORNING INTO THIS AFTERNOON...AND SUCH WORDING IS CAPTURED IN THE FORECAST. GUIDANCE SUGGESTS AN INCREASED LOW LEVEL PRESSURE GRADIENT WILL CONTINUE PROMOTING A STRONG LOW LEVEL WIND FIELD ACROSS OUR AREA THROUGH THIS AFTERNOON AND PERHAPS INTO THIS EVENING. GUIDANCE ALSO SUGGESTS PERIODIC WIND ADVISORY-WORTHY WINDS WILL BE OBSERVED ACROSS PORTIONS OF SOUTH CENTRAL NEBRASKA NEAR I-80...BUT THESE LOCATIONS ARE ALREADY COVERED WITH A WINTER WEATHER ADVISORY. GIVEN THE DECREASE IN SNOWFALL RATES ACROSS OUR SOUTH/SOUTHWEST...OPTED TO ALLOW THE WINTER WEATHER ADVISORY TO EXPIRE ACROSS OUR KANSAS COUNTIES. WITH SNOWFALL CONTINUING ACROSS PORTIONS OF SOUTH CENTRAL NEBRASKA...WENT AHEAD AND LET THE WINTER WEATHER ADVISORY RIDE FOR MANY OF OUR NEBRASKA COUNTIES THROUGH 21Z. OVERALL THIS WEATHER SYSTEM IS BEHAVING AS EXPECTED AND THE FORECAST REMAINS IN GOOD SHAPE. BESIDES THE AFOREMENTIONED ADJUSTMENTS TO THE HEADLINES...POPS AND WEATHER GRIDS...ALSO TWEAKED HOURLY TEMPERATURE...DEW POINT AND WIND GRIDS TO BETTER REFLECT CURRENT CONDITIONS. UPDATE ISSUED AT 815 AM CDT THU APR 18 2013 FYI WE ARE FORECASTING RECORD COLD HIGH TEMPS TODAY. IN THE 117 YEARS OF RECORDS AT GRI AND 106 YEARS AT HSI...HIGH TEMPS HAVE NEVER BEEN COLDER ON APR 18TH THAN WHAT WE/RE FCSTG TODAY. HERE ARE THE RECORDS... GRI 40 IN 1944 1912 1910 HSI 41 IN 1944 && .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 355 AM CDT THU APR 18 2013 MAIN FORECAST CONCERNS SURROUND THE PRECIPITATION ACROSS THE AREA AND TEMPERATURES. RADAR AND OBSERVATIONS SHOW PRECIPITATION ACROSS THE FORECAST AREA THIS MORNING. TO THE NORTHWEST THIS SHOULD BE ALL SNOW WITH SURFACE TEMPERATURES JUST BELOW FREEZING AND FORECAST SOUNDINGS HAVE TEMPERATURES BELOW FREEZING THROUGH THE PROFILE. FURTHER TO THE SOUTH AND EAST THERE IS SOME QUESTION. EARLIER REPORTS WERE OF SOME SLEET AND EVEN RAIN BUT RECENT REPORTS HAVE BEEN ALL SNOW. THE UPPER LEVEL LOW MOVES OFF TO THE NORTHEAST AND COLDER AIR CONTINUES TO MOVE INTO THE AREA. EXPECT SNOW ACROSS THE AREA TODAY. THE SNOW THIS MORNING HAS BEEN IN BANDS AND UNDER THE BANDS IT IS SNOWING FAIRLY HARD...BUT BETWEEN THE SNOW IS LIGHTER. SNOW FALL AMOUNTS ARE A BIT TRICKY. MOST OF THE SNOW WILL BE BEFORE SUN RISE THIS MORNING WITH LESSER AMOUNTS DURING THE DAY. MODELS ARE SIMILAR IN MOVING PRECIPITATION OUT OF THE AREA AS THE UPPER LOW MOVES OFF TO THE NORTHEAST. EXPECT THAT SNOW WILL END ACROSS THE SOUTHWEST BY MID AFTERNOON AND OUT OF THE NORTHEAST EARLY IN THE EVENING. THE QUESTION FOR THIS AFTERNOON WILL BE WHETHER THE SNOW WILL CHANGE BACK TO RAIN AS THE TEMPERATURES WARM UP. HAVE LEFT IT AS SNOW FOR NOW EXPECTING THAT BY THE TIME IT WARMS UP THE PRECIPITATION SHOULD BE COMING TO AN END. HIGH TEMPERATURES TODAY WILL BE IN THE 30S. CLOUDS WILL CONTINUE THIS EVENING AFTER THE SNOW COMES TO AN END BUT GRADUAL CLEARING FROM THE WEST IS EXPECTED LATER TONIGHT. WITH THE CLEARING SKIES AND WINDS WEAKENING SOME DURING THE NIGHT...EXPECT TEMPERATURES TO DROP OFF TO LOWS IN THE LOWER TO MID 20S. .LONG TERM...(FRIDAY THROUGH WEDNESDAY) ISSUED AT 355 AM CDT THU APR 18 2013 FRIDAY MORNING THE UPPER VORTEX WILL BE MOVING INTO THE GREAT LAKES REGION...WHILE ACROSS OUR REGION...NORTHWEST FLOW WILL BE IN PLACE ACROSS THE CENTRAL PLAINS. MODELS INDICATE A 80KT JET STREAK NOSING SOUTHEAST ON THE BACK SIDE OF THE TROUGH FM THE DAKOTAS FRIDAY IN THE NW FLOW REGIME...WHICH REACHES EAST CENTRAL/EASTERN NEB FRIDAY AFTN. FORECAST SOUNDINGS INDICATE CONVECTIVE TEMPS IN THE MID/UPPER 40S...AND AFTN HIGHS ARE FORECAST NEAR THIS AND WITH INCREASING DYNAMICS WITH SHEARED SHORTWAVE ENERGY AND JET...HAVE WENT AHEAD AND INCLUDED SPRINKLE POTENTIAL FOR THE AFTN. SREF POPS ARE FAIRLY HIGH IN THE 30 TO 40 PCNT RANGE...BUT FEEL SPRINKLES SHOULD COVER THINGS FOR NOW. DRY CONDITIONS BUT COOL CONDITIONS ARE FORECAST FRIDAY NIGHT WITH LOWS IN THE UPPER 20S/LOW 30S. THE AIRMASS BEGINS TO MODERATE OVER THE WEEKEND BEHIND THE DEPARTING UPPER TROUGH. WARM FRONT LIFTS E/NE ON SATURDAY AND TEMPS SHOULD CLIMB CLOSER TO SEASONAL NORMALS. A MID LEVEL SHORTWAVE TROUGH AND ASSOCIATED SFC TROUGH/COOL FRONT TRANSLATE EAST SATURDAY NIGHT BRINGING SLIGHT CHCS FOR PCPN. THE UPPER WAVE TRANSLATES ACROSS THE PLAINS SUNDAY WITH CONTINUED CHCS FOR CONVECTION IN UPPER DYNAMICS. THE WEATHER PATTERN NEXT WEEK REMAINS ACTIVE WITH AN UPPER TROUGH OVER CANADA SWINGING SOUTH FM THE NORTHERN PLAINS MONDAY NIGHT INTO TUESDAY. SIMILAR TO THE LAST FEW WEEKS...CONVECTIVE POTENTIAL EXISTS AHEAD OF THE SYSTEM...WITH AIRMASS PROGGED COLD ENOUGH FOR A RAIN/SNOW MIX OR MAYBE EVEN A CHANGE TO SNOW FOR SOME AREAS MONDAY NIGHT. UNSEASONALLY COLD TEMPERATURES WILL RETURN FOR SEVERAL DAYS TO START THE WORK WEEK WITH CONDITIONS DRYING OUT BEHIND THE TROUGH TUESDAY NIGHT. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON) ISSUED AT 1222 PM CDT THU APR 18 2013 IFR CONDITIONS TO CONTINUE THROUGH THIS AFTERNOON AND PERHAPS THIS EVENING...WITH VFR CONDITIONS EXPECTED THEREAFTER. BLOWING SNOW WILL CONTINUE RESTRICTING THE VISIBILITY TO AROUND 1SM THIS AFTERNOON...AND PERHAPS INTO THIS EVENING. THE LOW LEVEL WIND FIELD IS EXPECTED TO DIMINISH IN INTENSITY THIS EVENING THUS ALLOWING FOR IMPROVED VISIBILITY. THE CEILING WILL VARY BETWEEN 2500FT AND 3500FT AGL THROUGH THROUGH THIS EVENING AS WELL...BEFORE A PREVAILING VFR CEILING PRESENTS ITSELF TONIGHT INTO TOMORROW. THE SURFACE WIND WILL REMAIN FROM THE NORTHWEST...SUSTAINED AT AROUND 20KTS AND GUSTING NEAR 30KTS THROUGH THIS EVENING...DECREASING TO AROUND 12KTS TONIGHT. && .GID WATCHES/WARNINGS/ADVISORIES... NE...WINTER WEATHER ADVISORY UNTIL 4 PM CDT THIS AFTERNOON FOR NEZ039>041-046>049-060>064-072>076-082>085. KS...NONE. && $$ 1045 AM UPDATE...BRYANT 0815 AM UPDATE...HALBLAUB SHORT TERM...JCB LONG TERM...FAY AVIATION...BRYANT
AREA FORECAST DISCUSSION
NWS HASTINGS NE
1045 AM CDT THU APR 18 2013 .UPDATE... ISSUED AT 1045 CDT THU APR 18 2013 AS OF 15Z...WATER VAPOR IMAGERY INDICATES THE MID LEVEL LONGWAVE TROUGH EXTENDING FROM SOUTH CENTRAL CANADA INTO THE CENTRAL AND SOUTHERN PLAINS. AN ENHANCED AREA OF MID LEVEL VORTICITY IS ALSO NOTED OVER PORTIONS OF SOUTH DAKOTA AND NEBRASKA. ENHANCED MID LEVEL MOISTURE IS NOTED EXTENDING FROM THE SOUTHERN PLAINS...NORTHEAST INTO THE OHIO RIVER VALLEY. A MID LEVEL DRY INTRUSION IS EVIDENT FROM NORTH TEXAS INTO EASTERN KANSAS...SOUTHEASTERN NEBRASKA AND PORTIONS OF IOWA. AN AXIS MID LEVEL DEFORMATION...TO THE WEST/NORTHWEST OF THE ENHANCED VORTICITY EMBEDDED WITHIN THE LONGWAVE TROUGH...IS ALSO NOTED EXTENDING FROM EASTERN NORTH DAKOTA INTO PORTIONS OF NEBRASKA. RADAR DATA FROM KUEX INDICATES BANDED SNOWFALL CONTINUING OVER THE EASTERN HALF OF OUR CWA...WITH NOTHING MORE THAN LIGHT SNOW OR SNOW FLURRIES ACROSS OUR EAST. THE SURFACE WIND REMAINS VERY STRONG ACROSS OUR AREA...SUSTAINED FROM THE NORTHWEST AT 15-25KTS WITH HIGHER GUSTS. THE BANDED SNOWFALL ACROSS EASTERN PORTIONS OF OUR CWA APPEARS TO BE A DIRECT RESULT OF THE AFOREMENTIONED MID LEVEL DEFORMATION AXIS CURRENTLY MOVING EAST ACROSS THE REGION. GUIDANCE FROM THE NAM...OPERATIONAL GFS...EC...SREF-MEAN...AND RAP ALL SUGGEST THIS AXIS OF DEFORMATION WILL CONTINUE MOVING EAST TODAY AND AS A RESULT...THE BAND OF SNOWFALL CURRENTLY OVER PORTIONS OF OUR AREA SHOULD ALSO CONTINUE MOVING EAST OUT OF OUR AREA THROUGH THIS AFTERNOON. GIVEN THE CURRENT SATELLITE AND RADAR TRENDS...AS WELL AS MODEL GUIDANCE...WENT AHEAD AND CUT POPS ACROSS WEST/SOUTHWESTERN PORTIONS OF OUR CWA THROUGH THE REMAINDER OF THE DAY. CERTAINLY THERE COULD BE PERIODIC LIGHT SNOW OR SNOW FLURRIES OUT THAT WAY...BUT THE CHANCES OF MEASURABLE PRECIPITATION BEING OBSERVED THROUGH THE REST OF TODAY ARE FAR TOO LOW TO KEEP IN THE FORECAST. WENT AHEAD LINGERED PRECIPITATION OVER OUR EAST/NORTHEAST THROUGH EARLY TO MID-AFTERNOON...WITH DRY CONDITIONS EXPECTED FOR THE MOST PART LATE AFTERNOON. GIVEN THE CURRENT SPEED OF THE SNOW BAND ACROSS OUR AREA AND OBSERVATIONS FROM ACROSS THE AREA...IT SEEMS LOGICAL THAT LOCATIONS WHO OBSERVE SNOWFALL UNDERNEATH THE BAND COULD PICKUP AN ADDITIONAL INCH OF SNOWFALL THIS MORNING INTO THIS AFTERNOON...AND SUCH WORDING IS CAPTURED IN THE FORECAST. GUIDANCE SUGGESTS AN INCREASED LOW LEVEL PRESSURE GRADIENT WILL CONTINUE PROMOTING A STRONG LOW LEVEL WIND FIELD ACROSS OUR AREA THROUGH THIS AFTERNOON AND PERHAPS INTO THIS EVENING. GUIDANCE ALSO SUGGESTS PERIODIC WIND ADVISORY-WORTHY WINDS WILL BE OBSERVED ACROSS PORTIONS OF SOUTH CENTRAL NEBRASKA NEAR I-80...BUT THESE LOCATIONS ARE ALREADY COVERED WITH A WINTER WEATHER ADVISORY. GIVEN THE DECREASE IN SNOWFALL RATES ACROSS OUR SOUTH/SOUTHWEST...OPTED TO ALLOW THE WINTER WEATHER ADVISORY TO EXPIRE ACROSS OUR KANSAS COUNTIES. WITH SNOWFALL CONTINUING ACROSS PORTIONS OF SOUTH CENTRAL NEBRASKA...WENT AHEAD AND LET THE WINTER WEATHER ADVISORY RIDE FOR MANY OF OUR NEBRASKA COUNTIES THROUGH 21Z. OVERALL THIS WEATHER SYSTEM IS BEHAVING AS EXPECTED AND THE FORECAST REMAINS IN GOOD SHAPE. BESIDES THE AFOREMENTIONED ADJUSTMENTS TO THE HEADLINES...POPS AND WEATHER GRIDS...ALSO TWEAKED HOURLY TEMPERATURE...DEW POINT AND WIND GRIDS TO BETTER REFLECT CURRENT CONDITIONS. UPDATE ISSUED AT 815 AM CDT THU APR 18 2013 FYI WE ARE FORECASTING RECORD COLD HIGH TEMPS TODAY. IN THE 117 YEARS OF RECORDS AT GRI AND 106 YEARS AT HSI...HIGH TEMPS HAVE NEVER BEEN COLDER ON APR 18TH THAN WHAT WE/RE FCSTG TODAY. HERE ARE THE RECORDS... GRI 40 IN 1944 1912 1910 HSI 41 IN 1944 && .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 355 AM CDT THU APR 18 2013 MAIN FORECAST CONCERNS SURROUND THE PRECIPITATION ACROSS THE AREA AND TEMPERATURES. RADAR AND OBSERVATIONS SHOW PRECIPITATION ACROSS THE FORECAST AREA THIS MORNING. TO THE NORTHWEST THIS SHOULD BE ALL SNOW WITH SURFACE TEMPERATURES JUST BELOW FREEZING AND FORECAST SOUNDINGS HAVE TEMPERATURES BELOW FREEZING THROUGH THE PROFILE. FURTHER TO THE SOUTH AND EAST THERE IS SOME QUESTION. EARLIER REPORTS WERE OF SOME SLEET AND EVEN RAIN BUT RECENT REPORTS HAVE BEEN ALL SNOW. THE UPPER LEVEL LOW MOVES OFF TO THE NORTHEAST AND COLDER AIR CONTINUES TO MOVE INTO THE AREA. EXPECT SNOW ACROSS THE AREA TODAY. THE SNOW THIS MORNING HAS BEEN IN BANDS AND UNDER THE BANDS IT IS SNOWING FAIRLY HARD...BUT BETWEEN THE SNOW IS LIGHTER. SNOW FALL AMOUNTS ARE A BIT TRICKY. MOST OF THE SNOW WILL BE BEFORE SUN RISE THIS MORNING WITH LESSER AMOUNTS DURING THE DAY. MODELS ARE SIMILAR IN MOVING PRECIPITATION OUT OF THE AREA AS THE UPPER LOW MOVES OFF TO THE NORTHEAST. EXPECT THAT SNOW WILL END ACROSS THE SOUTHWEST BY MID AFTERNOON AND OUT OF THE NORTHEAST EARLY IN THE EVENING. THE QUESTION FOR THIS AFTERNOON WILL BE WHETHER THE SNOW WILL CHANGE BACK TO RAIN AS THE TEMPERATURES WARM UP. HAVE LEFT IT AS SNOW FOR NOW EXPECTING THAT BY THE TIME IT WARMS UP THE PRECIPITATION SHOULD BE COMING TO AN END. HIGH TEMPERATURES TODAY WILL BE IN THE 30S. CLOUDS WILL CONTINUE THIS EVENING AFTER THE SNOW COMES TO AN END BUT GRADUAL CLEARING FROM THE WEST IS EXPECTED LATER TONIGHT. WITH THE CLEARING SKIES AND WINDS WEAKENING SOME DURING THE NIGHT...EXPECT TEMPERATURES TO DROP OFF TO LOWS IN THE LOWER TO MID 20S. .LONG TERM...(FRIDAY THROUGH WEDNESDAY) ISSUED AT 355 AM CDT THU APR 18 2013 FRIDAY MORNING THE UPPER VORTEX WILL BE MOVING INTO THE GREAT LAKES REGION...WHILE ACROSS OUR REGION...NORTHWEST FLOW WILL BE IN PLACE ACROSS THE CENTRAL PLAINS. MODELS INDICATE A 80KT JET STREAK NOSING SOUTHEAST ON THE BACK SIDE OF THE TROUGH FM THE DAKOTAS FRIDAY IN THE NW FLOW REGIME...WHICH REACHES EAST CENTRAL/EASTERN NEB FRIDAY AFTN. FORECAST SOUNDINGS INDICATE CONVECTIVE TEMPS IN THE MID/UPPER 40S...AND AFTN HIGHS ARE FORECAST NEAR THIS AND WITH INCREASING DYNAMICS WITH SHEARED SHORTWAVE ENERGY AND JET...HAVE WENT AHEAD AND INCLUDED SPRINKLE POTENTIAL FOR THE AFTN. SREF POPS ARE FAIRLY HIGH IN THE 30 TO 40 PCNT RANGE...BUT FEEL SPRINKLES SHOULD COVER THINGS FOR NOW. DRY CONDITIONS BUT COOL CONDITIONS ARE FORECAST FRIDAY NIGHT WITH LOWS IN THE UPPER 20S/LOW 30S. THE AIRMASS BEGINS TO MODERATE OVER THE WEEKEND BEHIND THE DEPARTING UPPER TROUGH. WARM FRONT LIFTS E/NE ON SATURDAY AND TEMPS SHOULD CLIMB CLOSER TO SEASONAL NORMALS. A MID LEVEL SHORTWAVE TROUGH AND ASSOCIATED SFC TROUGH/COOL FRONT TRANSLATE EAST SATURDAY NIGHT BRINGING SLIGHT CHCS FOR PCPN. THE UPPER WAVE TRANSLATES ACROSS THE PLAINS SUNDAY WITH CONTINUED CHCS FOR CONVECTION IN UPPER DYNAMICS. THE WEATHER PATTERN NEXT WEEK REMAINS ACTIVE WITH AN UPPER TROUGH OVER CANADA SWINGING SOUTH FM THE NORTHERN PLAINS MONDAY NIGHT INTO TUESDAY. SIMILAR TO THE LAST FEW WEEKS...CONVECTIVE POTENTIAL EXISTS AHEAD OF THE SYSTEM...WITH AIRMASS PROGGED COLD ENOUGH FOR A RAIN/SNOW MIX OR MAYBE EVEN A CHANGE TO SNOW FOR SOME AREAS MONDAY NIGHT. UNSEASONALLY COLD TEMPERATURES WILL RETURN FOR SEVERAL DAYS TO START THE WORK WEEK WITH CONDITIONS DRYING OUT BEHIND THE TROUGH TUESDAY NIGHT. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z FRIDAY MORNING) ISSUED AT 547 AM CDT THU APR 18 2013 ANOTHER BAND OF SNOW HAS FORMED AND WILL BE MOVING THROUGH THE KGRI TERMINAL AREA IN THE NEXT FEW HOURS. BEHIND THIS BAND THERE WILL BE IMPROVING CONDITIONS THROUGH EARLY IN THE AFTERNOON. DURING THE EVENING CLOUDS WILL START TO DECREASE AND VFR CONDITIONS WILL BE FOUND LATE THIS AFTERNOON. && .GID WATCHES/WARNINGS/ADVISORIES... NE...WINTER WEATHER ADVISORY UNTIL 4 PM CDT THIS AFTERNOON FOR NEZ039>041-046>049-060>064-072>076-082>085. KS...NONE. && $$ UPDATE...BRYANT SHORT TERM...JCB LONG TERM...FAY AVIATION...JCB
AREA FORECAST DISCUSSION
NWS BURLINGTON VT
126 PM EDT THU APR 18 2013 .SYNOPSIS... A WARM FRONT WILL APPROACH THE REGION TODAY...AND THEN MOVE NORTH INTO CANADA TONIGHT. IT WILL BE WARM AND BECOMING WINDY TODAY AND FRIDAY AS GUSTY SOUTHERLY WINDS WILL BRING MUCH WARMER AIR TO THE NORTH COUNTRY...WITH HIGHS IN THE 70S ON FRIDAY. A COLD FRONT WILL MOVE INTO THE REGION LATE FRIDAY AFTERNOON AND THEN MOVE ACROSS THE AREA FRIDAY NIGHT...BRINGING RAIN SHOWERS TO THE NORTH COUNTRY. IT WILL BE MUCH COOLER AND BREEZY ON SATURDAY. A HIGH PRESSURE AREA OVER THE GREAT LAKES WILL BUILD INTO THE REGION SATURDAY NIGHT AND SUNDAY. && .NEAR TERM /UNTIL 8 PM THIS EVENING/... AS OF 121 PM EDT THURSDAY...WIND GUSTS NO SIGNIFICANT CHANGES FOR THIS LATEST UPDATE. AREA OF SHOWERS HAS MOVED THROUGH AND OUT OF OUR FORECAST AREA. PREVIOUS DISCUSSION FROM 451 AM EDT THURSDAY...WARM FRONT WILL LIFT NORTHEAST THROUGH THE REGION TODAY BRINGING CLOUDS...ALONG WITH A CHANCE OF RAIN SHOWERS MAINLY OVER THE SAINT LAWRENCE VALLEY AND THE ADIRONDACKS. TEMPERATURES WILL CLIMB TO THE UPPER 50S TO LOWER 60S TODAY. SURFACE PRESSURE GRADIENT TO TIGHTEN THIS AFTERNOON...SO COULD SEE SOME SOUTHERLY WIND GUSTS UP TO 40 MPH POSSIBLE THIS AFTERNOON FROM THE CHAMPLAIN VALLEY WESTWARD ACROSS NORTHERN NEW YORK. MOS POPS LOOK TOO HIGH FOR TODAY...SO HAVE LOWERED THEM QUITE A BIT. && .SHORT TERM /8 PM THIS EVENING THROUGH SATURDAY/... AS OF 451 AM EDT THURSDAY...THE WARM FRONT WILL LIFT NORTHEAST INTO QUEBEC TONIGHT. HAVE GONE WITH A DRY FORECAST FOR TONIGHT... AS THE BEST LIFT ASSOCIATED WITH THE WARM FRONT WILL BE IN CANADA. THUS...HAVE GREATLY LOWERED MOS POPS FOR TONIGHT. GUSTY SOUTHERLY WINDS WILL CONTINUE INTO TONIGHT...AND THIS WILL HELP TO KEEP TEMPERATURES UP TONIGHT. HAVE GONE SEVERAL DEGREES WARMER THAN THE GFS MOS GUIDANCE FOR MIN TEMPERATURES TONIGHT. ON FRIDAY...GUSTY SOUTHERLY WINDS WILL CONTINUE AS SURFACE PRESSURE GRADIENT REMAINS TIGHT ACROSS THE REGION. SOUTHERLY WIND GUSTS COULD APPROACH 50 MPH FRIDAY AFTERNOON ACROSS WESTERN VERMONT AND NORTHERN NEW YORK. GIVEN THAT THIS WILL OCCUR LATE IN THE THIRD PERIOD OF THE FORECAST...HAVE HELD OFF ON ANY WIND ADVISORY AT THIS TIME. WILL LET LATER SHIFTS REVIEW LATER GUIDANCE BEFORE MAKING ANY DECISION ON A WIND ADVISORY. HAVE MENTIONED THIS POSSIBILITY IN THE HAZARDOUS WEATHER OUTLOOK PRODUCT. EXPECTING FRIDAY TO START OUT AS A MAINLY DRY DAY ACROSS THE REGION WITH TEMPERATURES CLIMBING INTO THE 70S FRIDAY AFTERNOON. THE BEST CHANCE FOR RAIN SHOWERS FOR LATER FRIDAY AFTERNOON WILL BE ACROSS THE SAINT LAWRENCE VALLEY AND THE ADIRONDACKS IN NORTHERN NEW YORK...AS THE COLD FRONT MOVES INTO THE REGION. HAVE HELD OFF ON BRINGING RAIN SHOWERS FOR THE CHAMPLAIN VALLEY AND VERMONT UNTIL FRIDAY NIGHT. MODELS SHOW A MID LEVEL DRY SLOT WILL WORK INTO THE REGION LATE FRIDAY NIGHT...SO EXPECTING ANY RAIN SHOWER ACTIVITY WILL COME TO AN END BEFORE DAYBREAK ON SATURDAY. MUCH COOLER TEMPERATURES WILL BE OVER THE REGION ON SATURDAY. HAVE PUT IN SLIGHT CHANCE POPS OVER THE MOUNTAINS FOR RAIN SHOWERS ON SATURDAY. && .LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/... AS OF 510 AM EDT THURSDAY...OVERALL GOOD AGREEMENT BTWN GFS/ECMWF FOR THE WEEKEND AND INTO EARLY NEXT WK...THEN UNCERTAINTY DEVELOPS AS PATTERN BECMG MORE ACTIVE. SFC HIGH PRES WL RESULT IN MAINLY CLR SKIES AND DRY CONDITIONS FOR SUNDAY/MONDAY. GIVEN DEEP DRY AIRMASS ACRS THE NE CONUS...EXPECT LARGE SWINGS IN DIURNAL TEMPS FROM LOWS SAT NIGHT/SUNDAY NIGHT TO HIGHS ON SUNDAY/MONDAY. TEMPS WL BE 4 TO 8 DEGREES BLW NORMAL. THE 00Z ECMWF HAS TRENDED TWD THE GFS/GFS ENSEMBLE AND GEM FOR TUESDAY...WITH TRACK WELL TO OUR SOUTH AND EAST. GIVEN UNCERTAINTY WITH ANTICYCLONIC FLW AROUND HIGH PRES AND POTENTIAL FOR SOME MOISTURE TO ADVECT BACK INTO OUR CENTRAL/EASTERN CWA WL MENTION SCHC/LOW CHC POPS. ALSO...THIS WL CONT WITH PREVIOUS FCSTER THINKING. OTHERWISE...MODELS ARE IN RELATIVELY GOOD AGREEMENT WITH NEXT LARGE SCALE SYNOPTIC SYSTEM IMPACTING OUR REGION LATE WEDS INTO THURS. ONCE AGAIN SFC LOW PRES WL TRACK TO OUR WEST...PLACING OUR CWA IN THE WARM SECTOR BY WEDS ALONG CHCS FOR PRECIP WED AFTN INTO THURS. TEMPS WL BE NEAR NORMAL TUES AND ABOVE NORMAL FOR WEDS INTO THURS. && .AVIATION /18Z THURSDAY THROUGH TUESDAY/... THROUGH 12Z FRIDAY...DEVELOPING STRONG SOUTHERLY SFC WINDS WILL CREATE AREAS OF MODERATE TURBULENCE AND AREAS OF POTENTIAL LLVL WIND SHEAR TODAY. AVIATION CHALLENGE THRU THIS EVENING WL BE PLACEMENT OF LIGHT RAIN SHOWERS THIS MORNING...FOLLOWED BY GUSTY WINDS. CRNT SFC ANALYSIS SHOWS HIGH PRES LOCATED OVER NORTHERN NEW ENGLAND WITH A SFC WARM FRNT LIFTING ACRS NORTHERN NY ATTM. THIS FRNT AND ASSOCIATED RIBBON OF DEEPER MOISTURE WL LIFT ACRS NORTHERN NY TAF SITES BTWN 12Z AND 15Z THIS MORNING. BASED OFF THE RAP 13 HAVE TEMPO A PERIOD OF -SHRA FOR MSS/SLK EARLY THIS MORNING. WL USE VCSH AT PBG/BTV BTWN 13-16Z. IN ADDITION...SFC GRADIENT WL INCREASE WITH GUSTY SOUTH WINDS ANTICIPATED. SOUNDINGS SHOW WIND GUSTS POTENTIAL BTWN 25 AND 30 KNTS THIS AFTN...AS SFC HEATING OCCURS. RAP SOUNDINGS SHOW GUST POTENTIAL BTWN 35 ADN 40 KNTS AT MSS/BTV/SLK BTWN 19Z AND 02Z TODAY. VFR CONDITIONS WL PREVAIL THRU TODAY. NAM AND RAP CONTS TO SHOW SOME LLVL RH/CLOUDS INCREASING THIS EVENING WITH THE POTENTIAL FOR SOME MVFR CIGS IN A STRATO CUMULUS DECK...NOT ANTICIPATING FOG/BR GIVEN LLVL WIND PROFILES...WL USE SCATTERED 1200 TO 1500 FT TO SHOW THIS POTENTIAL OUTLOOK 12Z FRIDAY THROUGH MONDAY... GUSTY SOUTHERLY WINDS WL CONT ON FRIDAY AS SFC LOW PRES TRACKS FROM THE GREAT LAKES INTO CENTRAL CANADA. A BROKEN LINE OF SHOWERS WL IMPACT OUR TAF SITES LATE FRIDAY INTO SATURDAY WITH A BRIEF PERIOD OF MVFR CONDITIONS POSSIBLE IN THE HEAVIER SHOWERS. OTHERWISE...SFC HIGH PRES AND VFR CONDITIONS PREVAIL SAT THRU EARLY NEXT WEEK. && .HYDROLOGY... AS OF 451 AM EDT THURSDAY...WARMER TEMPERATURES TODAY AND FRIDAY WILL RESULT IN MELTING SNOW ACROSS THE HIGHER ELEVATIONS OF THE ADIRONDACKS AND GREEN MOUNTAINS. RUNOFF FROM THIS SNOW MELT WILL LEAD TO SOME SHARP RISES ON AREA RIVERS TODAY THROUGH FRIDAY. HOWEVER...NO FLOODING IS EXPECTED AT THIS TIME. && .BTV WATCHES/WARNINGS/ADVISORIES... VT...NONE. NY...NONE. && $$ SYNOPSIS...WGH/NEILES NEAR TERM...WGH/NEILES SHORT TERM...WGH LONG TERM...TABER AVIATION...TABER HYDROLOGY...WGH
AREA FORECAST DISCUSSION
NWS BURLINGTON VT
1036 AM EDT THU APR 18 2013 .SYNOPSIS... A WARM FRONT WILL APPROACH THE REGION TODAY...AND THEN MOVE NORTH INTO CANADA TONIGHT. IT WILL BE WARM AND BECOMING WINDY TODAY AND FRIDAY AS GUSTY SOUTHERLY WINDS WILL BRING MUCH WARMER AIR TO THE NORTH COUNTRY...WITH HIGHS IN THE 70S ON FRIDAY. A COLD FRONT WILL MOVE INTO THE REGION LATE FRIDAY AFTERNOON AND THEN MOVE ACROSS THE AREA FRIDAY NIGHT...BRINGING RAIN SHOWERS TO THE NORTH COUNTRY. IT WILL BE MUCH COOLER AND BREEZY ON SATURDAY. A HIGH PRESSURE AREA OVER THE GREAT LAKES WILL BUILD INTO THE REGION SATURDAY NIGHT AND SUNDAY. && .NEAR TERM /UNTIL 8 PM THIS EVENING/... AS OF 1024 AM EDT THURSDAY...WIND GUSTS THIS AFTERNOON WILL BE VERY CLOSE TO CRITERIA FOR AN ADVISORY. MAY ISSUE AN ADVISORY WITH NEXT UPDATE AT 1730Z. INCREASED THE POPS ACROSS THE AREA WITH AREA OF SHOWERS MOVING ACROSS THE NORTHERN PART OF OUR CWA. PRECIPITATION WILL BE VERY LIGHT. PREVIOUS DISCUSSION FROM 451 AM EDT THURSDAY...WARM FRONT WILL LIFT NORTHEAST THROUGH THE REGION TODAY BRINGING CLOUDS...ALONG WITH A CHANCE OF RAIN SHOWERS MAINLY OVER THE SAINT LAWRENCE VALLEY AND THE ADIRONDACKS. TEMPERATURES WILL CLIMB TO THE UPPER 50S TO LOWER 60S TODAY. SURFACE PRESSURE GRADIENT TO TIGHTEN THIS AFTERNOON...SO COULD SEE SOME SOUTHERLY WIND GUSTS UP TO 40 MPH POSSIBLE THIS AFTERNOON FROM THE CHAMPLAIN VALLEY WESTWARD ACROSS NORTHERN NEW YORK. MOS POPS LOOK TOO HIGH FOR TODAY...SO HAVE LOWERED THEM QUITE A BIT. && .SHORT TERM /8 PM THIS EVENING THROUGH SATURDAY/... AS OF 451 AM EDT THURSDAY...THE WARM FRONT WILL LIFT NORTHEAST INTO QUEBEC TONIGHT. HAVE GONE WITH A DRY FORECAST FOR TONIGHT... AS THE BEST LIFT ASSOCIATED WITH THE WARM FRONT WILL BE IN CANADA. THUS...HAVE GREATLY LOWERED MOS POPS FOR TONIGHT. GUSTY SOUTHERLY WINDS WILL CONTINUE INTO TONIGHT...AND THIS WILL HELP TO KEEP TEMPERATURES UP TONIGHT. HAVE GONE SEVERAL DEGREES WARMER THAN THE GFS MOS GUIDANCE FOR MIN TEMPERATURES TONIGHT. ON FRIDAY...GUSTY SOUTHERLY WINDS WILL CONTINUE AS SURFACE PRESSURE GRADIENT REMAINS TIGHT ACROSS THE REGION. SOUTHERLY WIND GUSTS COULD APPROACH 50 MPH FRIDAY AFTERNOON ACROSS WESTERN VERMONT AND NORTHERN NEW YORK. GIVEN THAT THIS WILL OCCUR LATE IN THE THIRD PERIOD OF THE FORECAST...HAVE HELD OFF ON ANY WIND ADVISORY AT THIS TIME. WILL LET LATER SHIFTS REVIEW LATER GUIDANCE BEFORE MAKING ANY DECISION ON A WIND ADVISORY. HAVE MENTIONED THIS POSSIBILITY IN THE HAZARDOUS WEATHER OUTLOOK PRODUCT. EXPECTING FRIDAY TO START OUT AS A MAINLY DRY DAY ACROSS THE REGION WITH TEMPERATURES CLIMBING INTO THE 70S FRIDAY AFTERNOON. THE BEST CHANCE FOR RAIN SHOWERS FOR LATER FRIDAY AFTERNOON WILL BE ACROSS THE SAINT LAWRENCE VALLEY AND THE ADIRONDACKS IN NORTHERN NEW YORK...AS THE COLD FRONT MOVES INTO THE REGION. HAVE HELD OFF ON BRINGING RAIN SHOWERS FOR THE CHAMPLAIN VALLEY AND VERMONT UNTIL FRIDAY NIGHT. MODELS SHOW A MID LEVEL DRY SLOT WILL WORK INTO THE REGION LATE FRIDAY NIGHT...SO EXPECTING ANY RAIN SHOWER ACTIVITY WILL COME TO AN END BEFORE DAYBREAK ON SATURDAY. MUCH COOLER TEMPERATURES WILL BE OVER THE REGION ON SATURDAY. HAVE PUT IN SLIGHT CHANCE POPS OVER THE MOUNTAINS FOR RAIN SHOWERS ON SATURDAY. && .LONG TERM /SATURDAY NIGHT THROUGH WEDNESDAY/... AS OF 510 AM EDT THURSDAY...OVERALL GOOD AGREEMENT BTWN GFS/ECMWF FOR THE WEEKEND AND INTO EARLY NEXT WK...THEN UNCERTAINTY DEVELOPS AS PATTERN BECMG MORE ACTIVE. SFC HIGH PRES WL RESULT IN MAINLY CLR SKIES AND DRY CONDITIONS FOR SUNDAY/MONDAY. GIVEN DEEP DRY AIRMASS ACRS THE NE CONUS...EXPECT LARGE SWINGS IN DIURNAL TEMPS FROM LOWS SAT NIGHT/SUNDAY NIGHT TO HIGHS ON SUNDAY/MONDAY. TEMPS WL BE 4 TO 8 DEGREES BLW NORMAL. THE 00Z ECMWF HAS TRENDED TWD THE GFS/GFS ENSEMBLE AND GEM FOR TUESDAY...WITH TRACK WELL TO OUR SOUTH AND EAST. GIVEN UNCERTAINTY WITH ANTICYCLONIC FLW AROUND HIGH PRES AND POTENTIAL FOR SOME MOISTURE TO ADVECT BACK INTO OUR CENTRAL/EASTERN CWA WL MENTION SCHC/LOW CHC POPS. ALSO...THIS WL CONT WITH PREVIOUS FCSTER THINKING. OTHERWISE...MODELS ARE IN RELATIVELY GOOD AGREEMENT WITH NEXT LARGE SCALE SYNOPTIC SYSTEM IMPACTING OUR REGION LATE WEDS INTO THURS. ONCE AGAIN SFC LOW PRES WL TRACK TO OUR WEST...PLACING OUR CWA IN THE WARM SECTOR BY WEDS ALONG CHCS FOR PRECIP WED AFTN INTO THURS. TEMPS WL BE NEAR NORMAL TUES AND ABOVE NORMAL FOR WEDS INTO THURS. && .AVIATION /15Z THURSDAY THROUGH MONDAY/... THROUGH 12Z FRIDAY...DEVELOPING STRONG SOUTHERLY SFC WINDS WILL CREATE AREAS OF MODERATE TURBULENCE AND AREAS OF POTENTIAL LLVL WIND SHEAR TODAY. AVIATION CHALLENGE THRU THIS EVENING WL BE PLACEMENT OF LIGHT RAIN SHOWERS THIS MORNING...FOLLOWED BY GUSTY WINDS. CRNT SFC ANALYSIS SHOWS HIGH PRES LOCATED OVER NORTHERN NEW ENGLAND WITH A SFC WARM FRNT LIFTING ACRS NORTHERN NY ATTM. THIS FRNT AND ASSOCIATED RIBBON OF DEEPER MOISTURE WL LIFT ACRS NORTHERN NY TAF SITES BTWN 12Z AND 15Z THIS MORNING. BASED OFF THE RAP 13 HAVE TEMPO A PERIOD OF -SHRA FOR MSS/SLK EARLY THIS MORNING. WL USE VCSH AT PBG/BTV BTWN 13-16Z. IN ADDITION...SFC GRADIENT WL INCREASE WITH GUSTY SOUTH WINDS ANTICIPATED. SOUNDINGS SHOW WIND GUSTS POTENTIAL BTWN 25 AND 30 KNTS THIS AFTN...AS SFC HEATING OCCURS. RAP SOUNDINGS SHOW GUST POTENTIAL BTWN 35 ADN 40 KNTS AT MSS/BTV/SLK BTWN 19Z AND 02Z TODAY. VFR CONDITIONS WL PREVAIL THRU TODAY. NAM AND RAP CONTS TO SHOW SOME LLVL RH/CLOUDS INCREASING THIS EVENING WITH THE POTENTIAL FOR SOME MVFR CIGS IN A STRATO CUMULUS DECK...NOT ANTICIPATING FOG/BR GIVEN LLVL WIND PROFILES...WL USE SCATTERED 1200 TO 1500 FT TO SHOW THIS POTENTIAL OUTLOOK 12Z FRIDAY THROUGH MONDAY... GUSTY SOUTHERLY WINDS WL CONT ON FRIDAY AS SFC LOW PRES TRACKS FROM THE GREAT LAKES INTO CENTRAL CANADA. A BROKEN LINE OF SHOWERS WL IMPACT OUR TAF SITES LATE FRIDAY INTO SATURDAY WITH A BRIEF PERIOD OF MVFR CONDITIONS POSSIBLE IN THE HEAVIER SHOWERS. OTHERWISE...SFC HIGH PRES AND VFR CONDITIONS PREVAIL SAT THRU EARLY NEXT WEEK. && .HYDROLOGY... AS OF 451 AM EDT THURSDAY...WARMER TEMPERATURES TODAY AND FRIDAY WILL RESULT IN MELTING SNOW ACROSS THE HIGHER ELEVATIONS OF THE ADIRONDACKS AND GREEN MOUNTAINS. RUNOFF FROM THIS SNOW MELT WILL LEAD TO SOME SHARP RISES ON AREA RIVERS TODAY THROUGH FRIDAY. HOWEVER...NO FLOODING IS EXPECTED AT THIS TIME. && .BTV WATCHES/WARNINGS/ADVISORIES... VT...NONE. NY...NONE. && $$ SYNOPSIS...WGH/NEILES NEAR TERM...WGH/NEILES SHORT TERM...WGH LONG TERM...TABER AVIATION...TABER HYDROLOGY...WGH
AREA FORECAST DISCUSSION
NWS BINGHAMTON NY
652 AM EDT THU APR 18 2013 .SYNOPSIS... A WARM FRONT WILL MOVE THROUGH THE REGION TODAY...BRINGING MILDER TEMPERATURES THROUGH FRIDAY. A STRONG COLD FRONT IS EXPECTED TO CROSS THE AREA FRIDAY EVENING ACCOMPANIED BY SHOWERS...AND A CHANCE OF THUNDERSTORMS. COOLER TEMPERATURES WILL FOLLOW AGAIN THIS WEEKEND UNDER FAIR SKIES. && .NEAR TERM /THROUGH TONIGHT/... SHORT TERM GUIDANCE FROM THE NAM/GFS/WRF AND RAP MODELS ARE IN GOOD AGREEMENT TODAY...AND SUGGEST A MILD SURGE OF AIR OVERSPREADING THE REGION ASSOCIATED WITH A WARM FRONTAL PASSAGE ALOFT. LOW LEVEL MOISTURE NOTED WITHIN A MARINE LAYER EXTENDING NORTHWARD FROM THE MID-ATLANTIC STATES WILL MARR THE MILD FORECAST WITH AN ABUNDANCE OF CLOUDS TODAY. PREVIOUS FORECAST INCLUDED PATCHY DRIZZLE...HOWEVER THE ISENTROPIC LIFT ASSOCIATED WITH THE WARM FRONTAL BOUNDARY LOOKS TO BE FOCUSED WELL TO OUR NORTH ALONG THE 850 MB FRONTAL ZONE. THIS LEAVES MAINLY OROGRAPHIC EFFECTS TO SQUEEZE OUT ANY LIGHT PRECIP. THIS IS NOT TYPICALLY FAVORABLE DURING THE WELL MIXED DAYLIGHT HOURS...AND WE EXPECT CLOUD CEILINGS TO BE MODESTLY HIGH TODAY AND NOT CONDUCIVE TO DRIZZLE. DECIDED TO REMOVE MENTION OF PTCHY DRIZZLE FOR TODAY. && .SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/... THE SOUTH-SOUTHEASTERLY FLOW IMPINGING ON OUR HIGHER TERRAIN TONIGHT...ALONG WITH BOUNDARY LAYER COOLING AND SATURATION SEEMS TO OFFER THE BETTER OPPORTUNITY FOR DRIZZLE AFTER DARK. WILL KEEP THAT IN THE FORECAST ACROSS THE SOUTHERN TIER NY AND NEPA...AND REFINE THE FORECAST TO FEATURE DRIZZLE MAINLY OVER THE ELEVATIONS ABOVE 1200-1500 FEET. THE MORE INTERESTING PART OF THE FORECAST OCCURS LATER FRIDAY AFTERNOON AS THE MAIN COLD FRONT OF THE APPROACHING STORM SYSTEM CROSSES THE REGION. MODEL SOLUTIONS ARE CONSISTENT AND MAINTAIN THAT THE BULK OF RAIN ACTIVITY WILL BE BETWEEN ABOUT 21Z AND 02Z. FORECAST WIND PROFILES ARE IMPRESSIVE BOTH IN SPEED AND DIRECTIONAL SHEAR...BUT INSTABILITY IS WEAK WITHIN A MODERATELY MOIST ADIABATIC ENVIRONMENT. A FEW HUNDRED J/KG OF CAPE IS ENOUGH TO WARRANT MENTION OF THUNDER...BUT A SVR THREAT AT THIS TIME SEEMS LOW WITH THE EXPECTATION OF AN ABUNDANCE OF LOW CLOUD COVER LIMITING THE DIURNAL HEATING. THE SPC INDICATES GENERAL THUNDER FOR THE REGION BUT NO MENTION OF SVR. GRADIENT SYNOPTIC WINDS DO LOOK BLUSTERY IN THE 15-30 MPH RANGE...BUT AT THIS TIME SHOULD REMAIN SAFELY UNDER ANY KIND OF IMPACT THRESHOLDS. FRONTAL PASSAGE FRIDAY EVENING WILL USHER A GOOD SHOT OF RAIN AND THEN SOME MARKEDLY COLDER AIR HEADING INTO THE WEEKEND WITH OVERNIGHT TEMPS IN THE 30S AND A REBOUND ON SATURDAY ONLY INTO THE 40S. AM NOT TOO EXCITED ABOUT ANY LAKE RESPONSE...HOWEVER COLD ADVECTION CLOUDINESS IS EXPECTED INTO SATURDAY MORNING DESPITE SOME PRONOUNCED DRYING IN THE 1000-500 MB MEAN RH LAYER DEPICTED BY THE MODELS. HIGH PRESSURE BUILDS IN QUICKLY FOR SATURDAY WITH IMPROVING CONDITIONS AND EVENTUALLY CLEARING SKIES HEADING INTO SATURDAY NIGHT. && .LONG TERM /SUNDAY THROUGH WEDNESDAY/... 300 AM UPDATE...LATEST GFS/ECMWF, SHOWS THE ECMWF IN BETTER AGREEMENT WITH THE GFS, INDICATING A WEAKER AND FARTHER OUT TO SEA SFC LOW ALONG THE EAST COAST TUE/WED. CURRENT EXTENDED IN GOOD SHAPE, WILL CONTINUE WITH CHC/SLIGHT CHC POPS TUE THROUGH WEDNESDAY. PREVIOUS DISC... A FAIRLY QUIET PERIOD SHAPING UP FOR THE FIRST HALF OF THE EXTENDED PERIOD AS HIGH PRESSURE QUICKLY BUILDS IN FOLLOWING THE EARLY WEEKEND COLD FRONT. WITH ITS ARRIVAL...COOLER AIR WILL BE IN STORE WITH HIGHS ONLY EXPECTED TO WARM INTO THE UPPER 40S TO LOWER 50S ON SUNDAY. NEXT WX FEATURE OF INTEREST WILL BE A NORTHWARD LIFTING AREA OF LOW PRESSURE ALONG THE EASTERN SEABOARD WHICH THE ECMWF SHOWS MOVING INTO THE AREA SOMETIME DURING THE DAY ON TUESDAY. THE GFS ON THE OTHER HAND KEEPS THIS FEATURE WELL OFFSHORE WITH LITTLE TO NO IMPACT ON OUR AREA. FOR NOW...WILL MAINTAIN SLGT CHC TO CHC MENTION FOR OUR FCST AREA BEGINNING TUE WITH THIS TREND CONTINUING THROUGH THE CONCLUSION OF THE PERIOD AS BOTH THE GFS AND ECMWF SHOW THE NEXT WX SYSTEM/COLD FRONT APPROACHING FROM THE WEST BY MIDWEEK. NO SIGNIFICANT DEVIATIONS FROM HPC GUIDANCE. && .AVIATION /12Z THURSDAY THROUGH MONDAY/... A SFC WARM FRONT SOUTH OF THE REGION WILL LIFT NORTH THROUGH THE AREA LATER TODAY AND THIS EVENING. MOISTURE FROM THIS BOUNDARY AND INCREASING SOUTHEAST FLOW WILL LOWER CIGS TO AROUND 4K FT THIS MORNING. LIGHT SHOWERS ARE POSSIBLE AT KRME/KSYR THROUGH 14Z. CIGS WILL REMAIN AROUND THIS HEIGHT THROUGH THE DAY. THIS EVENING CIGS WILL LOWER INTO THE MVFR/LOW MVFR CATEGORY WITH DRIZZLE LIKELY LATER TONIGHT AT KAVP. E/SE WINDS AROUND 10 KNOTS BECOMING S/SE LATER THIS MORNING AT 12-18 KNOTS WITH GUSTS AROUND 25 KNOTS. S/SE WINDS OVERNIGHT AT 10-15 KNOTS. .OUTLOOK... FRI/FRI NGT...MVFR RESTRICTIONS POSSIBLE BY AFTERNOON IN SHRA- TSRA. SAT THROUGH MON...VFR UNDER HIGH PRESSURE. && .BGM WATCHES/WARNINGS/ADVISORIES... PA...NONE. NY...NONE. && $$ SYNOPSIS...MLJ NEAR TERM...MLJ/PVN SHORT TERM...MLJ LONG TERM...CMG/RRM AVIATION...RRM
AREA FORECAST DISCUSSION
NWS RALEIGH NC
125 PM EDT THU APR 18 2013 .SYNOPSIS... HIGH PRESSURE CENTERED OFF THE NEW ENGLAND COAST WILL EXTEND DOWN THE EAST COAST TODAY. A STRONG COLD FRONT WILL APPROACH FROM THE WEST TONIGHT... AND CROSS THE REGION FRIDAY AFTERNOON THROUGH FRIDAY NIGHT. COOL HIGH PRESSURE WILL BUILD IN FROM THE WEST ON SATURDAY. && .NEAR TERM /THROUGH TONIGHT/... AS OF 945 AM THURSDAY... TODAY: A WEAKENING MID-LEVEL SHORTWAVE UNDER THE WEST SIDE OF THE BROAD UPPER RIDGE WILL CONTINUE TO LIFT NORTHEAST TODAY. AS OF MID MORNING CENTRAL NORTH CAROLINA WAS UNDER A SURFACE THETA-E MINIMUM...AND WHILE THE 12Z KGSO SOUNDING SHOWED A VERY MOIST LAYER BETWEEN ABOUT 900MB AND 650MB WITH THE LAPSE RATE GREATER THAN MOIST ADIABATIC... DURING THE DAY BOTH THE GFS AND THE NAM FORECAST WARMING AND DRYING IN THAT LAYER. THIS SHOULD BE ENOUGH TO CAP THE ATMOSPHERE TO DEEP CONVECTION. THE RUC...GFS...AND THE NAM ALL SHOW NO QPF IN CENTRAL NORTH CAROLINA THIS AFTERNOON...AND THE HRRR WRF...ASIDE FROM WHAT APPEAR TO BE SOME SPOTTY CU...SEEMS ALSO TO BE VERY LIMITED WITH DEEP CONVECTION. WILL KEEP CHANCES FOR PRECIPITATION BELOW SLIGHT CHANCE THROUGH THE AFTERNOON...AND WITH THE SHORTWAVE THERE WILL BE AREAS OF CLOUDS THAT SHOULD GRADUALLY MIX AND BECOME INCREASINGLY SCATTERED WITH TIME. UNDER AN OVERALL PARTLY SUNNY SKY...1000-850MB THICKNESSES SUPPORT MAXES FROM AROUND 80 TO THE LOWER 80S...IN CONCERT WITH MOS GUIDANCE. MIXING SHOULD PROVIDE FOR SOME WIND GUSTS IN THE UPPER TEENS KNOTS AND A FEW LOWER 20S KNOTS AT TIMES PARTICULARLY FROM AROUND NOON THROUGH THE MIDDLE OF THE AFTERNOON. -DJF TONIGHT: STRENGTHENING SOUTHERLY MOISTURE TRANSPORT WITH THE APPROACH OF THE AMPLIFIED UPPER TROUGH AND ATTENDANT SURFACE COLD FRONT INTO THE TN VALLEY WILL LIKELY SUPPORT WIDESPREAD LOW CLOUDS INTO THE AREA AFTER MIDNIGHT WITH SPOTTY WAA SHOWERS OVERSPREADING THE AREA FROM OFF THE ATLANTIC/SOUTHEAST COAST. LOWS IN THE LOWER 60S. -CBL && .SHORT TERM /FRIDAY THROUGH SATURDAY NIGHT/... AS OF 250 AM THURSDAY... A DEAMPLIFYING UPPER TROUGH WILL CONTINUE TO MOVE EAST THROUGHOUT THE DAY ON FRIDAY...WITH THE PARENT SURFACE LOW MOVING WELL NORTH OF THE AREA ACROSS THE GREAT LAKES/CANADA. THE TRAILING COLD FRONT WILL CROSS OUR AREA FRIDAY/FRIDAY NIGHT WITH AN ACCOMPANYING LINE OF SHOWERS AND THUNDERSTORMS. WITH THE BEST FORCING MOVING NORTH OF THE REGION...THE MAIN CONCERN CONTINUES TO BE THE POTENTIAL FOR SEVERE WEATHER. MODELS ARE IN GOOD AGREEMENT WITH THE LINE OF SHOWERS AND THUNDERSTORMS MOVING ACROSS CENTRAL NC FROM WEST TO EAST FRIDAY AFTERNOON THROUGH EARLY SATURDAY MORNING. AS IS COMMONLY THE CASE...PLENTY OF SHEAR WILL BE IN PLACE...AS WELL AS DECENT LOW LEVEL LAPSE RATES AS TEMPS ARE EXPECTED TO RISE INTO THE UPPER 70S/LOWER 80S...BUT THE AMOUNT OF INSTABILITY WILL BE THE MAIN LIMITING FACTOR. MODELS CONTINUE TO PROG ONLY MARGINAL INSTABILITY...LIKELY DUE TO THE EXTENSIVE CLOUD COVER EXPECTED AHEAD OF THE APPROACHING FRONT...AS WELL AS THE SOMEWHAT NOCTURNAL TIMING OF THE PRECIP (THIS SECOND POINT WILL MOSTLY COME INTO PLAY FOR THE EASTERN PORTIONS OF THE FORECAST AREA). THE SPC DECIDED NOT TO UPGRADE THE AREA TO A DAY 2 SLIGHT RISK FOR NOW...MAINLY DUE TO POTENTIAL OF LIMITED INSTABILITY... ALTHOUGH THEY POINTED OUT THAT IF ENOUGH DESTABILIZATION DOES OCCUR...A SLIGHT RISK MAY EVENTUALLY BE NEEDED. NEVERTHELESS...WILL CONTINUE TO MENTION THE POSSIBILITY OF STRONG TO SEVERE STORMS...WITH THE PRIMARY THREAT BEING DAMAGING WIND...IN THE HWO. PRECIP IS EXPECTED TO COME TO AN END FROM WEST TO EAST SATURDAY MORNING...WITH HIGH PRESSURE BUILDING IN FOR SATURDAY NIGHT. HIGHS ON FRIDAY ARE EXPECTED TO RANGE FROM THE UPPER 70S ACROSS THE WEST TO LOW/MID 80S FURTHER EAST. OVERNIGHT LOWS ON FRIDAY NIGHT WILL BE DEPENDENT ON THE TIMING OF THE EXITING PRECIP AND COMMENCEMENT OF COLD AIR ADVECTION. AT THIS TIME...IT APPEARS PRECIP SHOULD CLEAR OUT OF AT LEAST THE WESTERN PORTIONS OF THE FORECAST AREA BEFORE DAYBREAK AND THEREFORE AM EXPECTING TEMPS TO RANGE FROM THE UPPER 40S/LOWER 50S ACROSS THE WEST TO MID/UPPER 50S FURTHER EAST. CONDITIONS WILL IMPROVE THROUGHOUT THE DAY ON SATURDAY AND WITH COLD AIR ADVECTION PERSISTING...HIGHS SHOULD GENERALLY BE IN THE MID/UPPER 60S. OVERNIGHT LOWS ARE EXPECTED TO FALL INTO THE 40S AREAWIDE SATURDAY NIGHT. && .LONG TERM /SUNDAY THROUGH WEDNESDAY/... AS OF 320 AM THURSDAY... COOL AND DRY CONDITIONS TO CLOSE THE WEEKEND AS A BROAD LONG WAVE TROUGH WILL ENCOMPASS MUCH OF THE CONUS WITH A STRONG MIGRATORY CANADIAN SURFACE HIGH BUILDING OVER THE NE US AND MID-ATLANTIC REGION BEFORE QUICKLY SHIFTING OFF THE NEW ENGLAND COAST. A BIT OF UNCERTAINTY BEGINS TO CREEP INTO THE PICTURE OWING TO NORTHERN STREAM AMPLIFICATION OVER THE ROCKIES AND INTO THE CENTRAL US EARLY NEXT WEEK. IN RESPONSE TO THE DIGGING TROUGH...MODELS SHOW WEAK CYCLOGENESIS ALONG THE STALLED BAROCLINIC FRONTAL ZONE OFF THE SOUTHEAST COAST WITH A POTENTIAL FOR ANOTHER HYBRID CAD EVENT EITHER MONDAY OR TUESDAY PENDING THE EVOLUTION OF THE SYSTEM(STRENGTH AND LOCATION OF THE COASTAL WAVE). THIS SCENARIO WOULD ONLY ENHANCE THE PERIOD OF BELOW NORMAL TEMPERATURES WITH THE POTENTIAL FOR THE RAIN AND ASSOCIATED WET BULB COOLING TO KEEP DAYTIME HIGHS IN THE LOWER 50S IF THE WETTER SOLUTIONS VERIFY. HAVE PLENTY TIME TO SIT AND WAIT FOR MODEL DIFFERENCES TO IRON THEMSELVES OUT BEFORE FORECASTING SUCH A DRASTIC CHANGE...BUT THE POTENTIAL IS DEFINITELY THERE GIVEN SUCH A STRONG 1040MB CANADIAN SURFACE HIGH OFF THE NEW ENGLAND COAST. THE LINGERING WEDGE PATTERN LEFT BEHIND WILL ATTEMPT TO ERODE BEFORE THE AFOREMENTIONED TROUGH AND ATTENDANT SFC COLD FRONT APPROACH THE AREA FROM THE WEST ON WEDNESDAY/THURSDAY BRINGING WIDESPREAD SHOWERS AND POSSIBLY THE THREAT OF STORMS. && .AVIATION /18Z THURSDAY THROUGH TUESDAY/... AS OF 125 PM THURSDAY... 24 HOUR TAF PERIOD: HIGH CONFIDENCE OF SUB-VFR CONDITIONS OVERNIGHT THURSDAY INTO FRIDAY MORNING. FOR THE REMAINDER OF THE DAY TODAY EXPECT SCATTERED TO BROKEN MID LEVEL CEILINGS TO BEGIN TO ERODE LATER THIS AFTERNOON WITH SCATTERED CUMULUS LEFT IN PLACE. SOUTH SOUTHEASTERLY WINDS WILL PREVAIL THROUGH THE EVENING AND WILL REMAIN IN THE 5-10 KNOT RANGE GUSTING TO 20 KNOTS. OVERNIGHT WINDS WILL REMAIN SOUTHERLY BUT MAY INCREASE TO 10-15 KNOTS SUSTAINED ESPECIALLY AT NORTHERN AND WESTERN TERMINALS. FURTHER SOUTH AND EAST EXPECT 5-10 KNOTS TO HOLD THROUGH THE NIGHT. AFTER 6Z CEILINGS ARE EXPECTED TO DROP TO IFR LEVELS AND WOULD NOT BE SURPRISED TO SEE LIFR AT TIMES. CONDITIONS SHOULD IMPROVE A FEW HOURS AFTER SUNRISE BUT MAY VERY WELL STAY IN THE MVFR RANGE UNTIL LATER IN THE AFTERNOON. AS SKIES BREAK OUT AND MIXING BEGINS WINDS WILL BE NEAR 15 KNOTS GUSTING TO 20-25 KNOTS ON FRIDAY WITH THE OCCASIONAL GUST TO 30 KNOTS POSSIBLE. WINDS WILL TAKE ON A MORE SOUTHWESTERLY DIRECTION BY THE END OF THE TAF PERIOD. LONG TERM: A STRONG FRONTAL SYSTEM IS EXPECTED TO CROSS THE AREA FRIDAY NIGHT. STRONG TO POTENTIALLY SEVERE THUNDERSTORMS WILL BE POSSIBLE WITH THIS SYSTEM. HEAVY RAIN IS ALSO EXPECTED. BEYOND FRIDAY...INTERMITTENT PERIODS OF SUB-VFR CONDITIONS WILL BE POSSIBLE THROUGH TUESDAY. && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...GIH NEAR TERM...DJF/CBL SHORT TERM...KRR LONG TERM...CBL AVIATION...ELLIS
AREA FORECAST DISCUSSION
NWS GRAND FORKS ND
105 PM CDT THU APR 18 2013 .UPDATE... ISSUED AT 105 PM CDT THU APR 18 2013 EARLY AFTERNOON UPDATE FOCUSES ON SNOW IN THE SOUTHEAST AND CLEARING SKIES IN THE NORTHWEST. WITH CLEARING AND DECREASING ECHOES ON RADAR...WILL REMOVE SARGENT COUNTY FROM ADVISORY BUT RETAIN SOME LIGHT SNOW IN THE REGION. THERE WILL BE A TIGHT QPF GRADIENT ORIENTED ALONG THE BORDER OF THE DLH AND MPX CWAS...WITH MY AREA ON THE DRIER SIDE. BOTH GFS AND NAM CONDENSATION PRESSURE DEFICITS DECREASE RAPIDLY THIS AFTN...NEARING 10+ VALUES BY 00Z. THINK SNOWFALL MAY TAPER OFF A BIT QUICKER...BUT THERE WILL ALSO BE A TIGHT GRADIENT WITH THE MAIN PRECIP SHIELD OVER THE MPX AREA. FOR THIS REASON...WILL LIKELY EXTEND THE ADVISORY FOR MY FAR SOUTHEASTERN COUNTIES...REMOVE RICHLAND COUNTY...AND POSSIBLY REMOVE WILKIN DEPENDING ON HOW THINGS LOOK NEARER THE 21Z FCST ISSUANCE TIME. IN GRANT...OTTER TAIL AND SOUTHERN WADENA COUNTIES (SPECIFICALLY THE FAR SOUTHERN PORTIONS OF THOSE COUNTIES)...MAY BE CLOSER TO 5 INCHES OF SNOW WITH 3 TO 5 AVERAGE ACROSS THOSE COUNTIES. THIS IS MAINLY DUE TO BRINGING HIGHER QPF VALUES A BIT FURTHER NORTH IN LINE WITH THE RUC GUIDANCE. WILL ADDRESS FURTHER DETAILS AT 21Z. && .SHORT TERM...(TODAY THROUGH FRIDAY) ISSUED AT 357 AM CDT THU APR 18 2013 WATER VAPOR LOOP INDICATED UPPER LEVEL TROUGH AXIS EXTENDED FROM WESTERN ND TO THE FOUR CORNERS REGION. UPPER LEVEL TROUGH AXIS TO MOVE EAST OF THE AREA BY LATE AFTERNOON OR EARLY EVENING. JET STREAKS WERE MOVING THROUGH THE FLOW AND EXPECT THE NEXT JET STREAK/ SHORT WAVE TO MOVE THROUGH LATER THIS MORNING. NOT MUCH CHANGE IN THE POPS FOR TODAY AND TONIGHT. RADAR/SURFACE OBS INDICATING LIGHT SNOW OVER THE CENTRAL RED RIVER VALLEY. PRECIPITATION WAS DISSIPATING AS PRECIPITATION MOVES NORTHEAST AT 25 TO 30 KNOTS. WILL KEEP WINTER WEATHER ADVISORY GOING IN THE SOUTHEAST ZONES FOR TODAY...THOUGH IT MAY BE MARGINAL. ANOTHER JET STREAK/SHORT WAVE OVER NORTHERN ALTA WILL MOVE ACROSS THE AREA THU NIGHT. PRECIPITATION WITH SHORT WAVE EXPECTED TO STAY WEST OF THE FORECAST AREA. UPPER LOW FORECAST TO CLOSE OFF ON FRI AND SURFACE LOW TO DEVELOP. SURFACE LOW OVER MO TO MOVE NORTHEAST AND TO BEGIN DEEPENING THIS AFTERNOON THROUGH FRI. NORTH SURFACE WIND EXPECTED TO INCREASE MAINLY OVER EASTERN ZONES TODAY THROUGH FRI MORNING. .LONG TERM...(FRIDAY NIGHT THROUGH WEDNESDAY) ISSUED AT 357 AM CDT THU APR 18 2013 ANOTHER SHORT WAVE IN THE EASTERN PACIFIC WILL MOVE THROUGH SAT AFTERNOON AND SAT NIGHT. WILL INCREASE POPS FOR THESE TIME PERIODS. TEMPS FORECAST TO BE ABOVE FREEZING IN THE SOUTHERN ZONES. WILL ADD THREAT OF RAIN OR SNOW IN THE SOUTH. MIXED PRECIPITATION (DIURNALLY DRIVEN) SUNDAY SHOULD BEGIN TO PUSH EAST OF THE NORTHERN PLAINS SUNDAY NIGHT/EARLY MONDAY TO BE FOLLOWED BY A RELATIVELY DRY FIRST HALF OF THE NEW WEEK. 00Z ECMWF/GFS AGREE ON LONG WAVE PROGRESSIVE TROUGH EAST OF REGION WITH ZONAL FLOW BECOMING NORTH TO NORTHWEST...BUT WITH FLOW ORIGINATING FROM PACIFIC NORTHWEST. ECMWF IS BONE DRY WITH HIGH PRESSURE DOMINATING MON THROUGH WED...SEEMINGLY OVERDONE ALBEIT SLIGHT CHANCE POPS PERSIST WITH THE GFS MOST OF THE PERIOD. GOOD NEWS LIES WITH THE THERMAL FIELDS...SUBZERO 925 MB TEMPS FINALLY LURCH ABOVE FREEZING BY WEDNESDAY...WITH VAST IMPROVEMENT AT THE 850 MB LEVEL AS WELL. THIS WILL BOLSTER SURFACE TEMPERATURES FROM THE LOW 40S LATE WEEKEND TO AROUND 50 BY MID WEEK. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON) ISSUED AT 105 PM CDT THU APR 18 2013 THERE WILL BE A BATTLE BETWEEN DRY AIR TO THE NORTH AND MOIST AIR TO THE SOUTH...WHICH CAN BE SEEN ON SATELLITE IMAGERY. KFAR AND KBJI WILL BE THE SITES THAT WILL BE IFR/MVFR INTO THE NIGHTTIME HOURS...WITH KBJI LIKELY IFR/MVFR INTO FRIDAY MORNING. STRONG NORTHERLY WINDS WILL SUBSIDE A BIT OVERNIGHT...BUT REMAIN BREEZY. && .FGF WATCHES/WARNINGS/ADVISORIES... ND...WINTER WEATHER ADVISORY UNTIL 7 PM CDT THIS EVENING FOR NDZ053. MN...WINTER WEATHER ADVISORY UNTIL 7 PM CDT THIS EVENING FOR MNZ024- 028>032-040. && $$ UPDATE...SPEICHER SHORT TERM...HOPPES LONG TERM...HOPPES/WJB AVIATION...TG
AREA FORECAST DISCUSSION
NWS SIOUX FALLS SD
1107 AM CDT THU APR 18 2013 .UPDATE... ISSUED AT 1107 AM CDT THU APR 18 2013 WELL FOR NOW...WE WILL LEAVE HEADLINES ALONE. UNSTABLE BANDED SNOWFALL IS OCCURRING ACROSS THE SIOUX FALLS FORECAST AREA...AND WILL BE SLOW TO DIMINISH. HOWEVER FROM I 29 AND POINTS WESTWARD...MOST OF THE ACCUMULATING SNOW WILL LIKELY FALL THROUGH MID AFTERNOON...LINGERING 3 OR 4 HOURS LONGER EAST OF I 29. SNOWFALL MEASUREMENTS COULD BE QUITE VARIABLE ACROSS THIS AREA DUE TO THE BANDED NATURE OF THE SNOW...A RATHER TYPICAL SPRING SYSTEM. SO PINNING DOWN EXACT SNOW AMOUNTS IS REALLY TOUGH FOR ANY ONE POINT LOCATION. THE SNOW WILL BE THE LAST TO EXIT OUR SOUTHWEST MN ZONES WHICH WILL BE TOWARD MIDNIGHT. THEREFORE WILL NOT ALTER THE WARNING AREA. CONCERNING THE WIND...VISIBILITIES ARE QUITE HORRENDOUS IN THE HEAVIER BANDS OF SNOW IN THE COUNTRY. THAT SAID... MUCH OF THE SNOW IS MELTING ON CONTACT ON WELL TRAVELED PAVEMENT...AND WILL CONTINUE TO DO SO FOR THE DAY HOURS. AM WORRIED THAT THIS EVENING THOUGH...THAT BLOWING SNOW ACROSS UNTREATED ROADWAYS WILL BEGIN TO FREEZE. ONE LAST NOTE...WE WILL PROBABLY BE ABLE TO CANCEL THE ADVISORY IN SOME OF OUR WESTERN ZONES WITH THE 4 PM PACKAGE. && .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 420 AM CDT THU APR 18 2013 UPPER LEVEL SUPPORT RAPIDLY EXPANDING NORTHWARD THIS MORNING AND WILL MAXIMIZE OVER SOUTHEAST SOUTH DAKOTA INTO NORTHWEST IOWA BY ABOUT 18Z TODAY. INSTABILITY FROM ABOUT 850MB TO 700MB OVER SOUTHEAST NEBRASKA INTO WESTERN IOWA ALLOWING CONVECTIVE ELEMENTS TO DEVELOP IN THOSE AREAS BUT THE INSTABILITY NOT REAL IMPRESSIVE SO NOT THINKING THAT IT WILL PLAY A HUGE ROLE IN THE WEATHER OVER THE NEXT 24 HOURS. DO EXPECT SOME INCREASED RAINFALL RATES IN NORTHWEST IOWA HOWEVER AND THE MAIN CONCERN WILL BE A RIBBON OF FREEZING PRECIPITATION AND SLEET FROM SIOUX CITY TOWARDS SHELDON INTO PARTS OF SOUTHWEST MINNESOTA THROUGH ABOUT LATE MORNING. FARTHER WEST IT SHOULD BE MAINLY SNOW AND A BAND OF HEAVY SNOWFALL STILL LOOKS GOOD FROM YANKTON TO SIOUX FALLS INTO SOUTHWEST MINNESOTA. UPPER LEVEL PV ADVECTION MAXIMIZES THIS MORNING AND THE 750MB TO 650MB FRONT IS PLANTED RIGHT OVER SOUTHEAST SOUTH DAKOTA INTO SOUTHWEST MINNESOTA. WHILE THERE IS SOME INSTABILITY ABOVE THE FRONT IT IS NOT NEARLY AS IMPRESSIVE AS LAST WEEKS SYSTEM. SO AT THIS TIME NOT PLANNING ON ANY THUNDER SNOW BUT SNOWFALL RATES OF AN INCH AN HOUR AT TIMES STILL LIKELY. THE BEST CHANCE FOR THE HEAVIEST SNOWFALL RATES WILL BE FROM ABOUT 12Z THROUGH 19Z SHIFTING FROM FROM SOUTH TO NORTH. STILL EXPECT SNOW TO CONTINUE THROUGH THE REMAINDER OF THE AFTERNOON AND EVENING...DECREASING PRETTY QUICKLY FOR THE WEST TONIGHT. THE 21Z SREF HAS PRETTY GOOD CLUSTERING AROUND 8 TENTHS OF AN INCH OF LIQUID AROUND SIOUX FALLS WHILE THE LATEST GEM/ECMWF/NAM ARE CLOSER TO 6 TO 7 TENTHS OF LIQUID. THE 3Z SREF HAS DROPPED OFF QUITE A BIT WITH STORM TOTAL LIQUID AFTER 12Z THIS MORNING ABOUT 0.45...THIS TAKING AWAY THE 0.13 IT HAD IN BEFORE 12Z WHICH DOES NOT LOOK LIKE IT WILL OCCUR. IN FACT MOST AREAS WEST OF A YANKTON TO SLAYTON LINE LIKELY WILL GET ONLY A COUPLE OF TENTHS OR LESS THROUGH 12Z THIS MORNING WITH MAYBE AN INCH OR SO FROM THE JAMES VALLEY WEST. TAKING THIS INTO ACCOUNT WITH ALL OF THE MODELS LOOKS LIKE WE WILL SETTLE IN TO MORE OF A 4 TO 6 TENTHS LIQUID POTENTIAL. GIVEN SOME COMPACTION AND MELTING AS IT FALLS 4 TO 6 INCHES SEEMS ABOUT RIGHT FOR THE SIOUX FALLS AREA WITH AN INCH OR TWO MORE IN SOUTHWEST MINNESOTA. A LITTLE WORRIED THAT THE SNOWFALL FALLING DURING THE DAY VERSUS AT NIGHT LIKE LAST WEEK AND LESS INSTABILITY THAN THAT SYSTEM AS WELL AS SURFACE TEMPERATURES ABOUT 2-3 DEGREES WARMER WILL KEEP AMOUNTS ABOUT 4-5 INCHES. LATEST RUNS OF THE HRRR AS WELL AS THE RAP KEEP THE BETTER AMOUNTS JUST EAST AND NORTH OF THE INTERSTATE 29 CORRIDOR WHICH MATCHES FAIRLY WELL WITH THE MID LEVEL BOUNDARY...AROUND 700MB AND THE EDGE OF THE DRY SLOT. .LONG TERM...(FRIDAY THROUGH WEDNESDAY) ISSUED AT 420 AM CDT THU APR 18 2013 FRIDAY AND SATURDAY WILL CONTINUE TO SEE BELOW NORMAL TEMPERATURES ESPECIALLY WITH THE SNOW COVER. ANOTHER SYSTEM WILL BRING THE CHANCE FOR RAIN OR SNOW TO THE AREA SATURDAY AND SATURDAY NIGHT BUT IS NOT EXPECTED TO BE A MAJOR IMPACT. THE SUNDAY INTO MIDDLE OF NEXT WEEK PERIOD IS CHARACTERIZED BY CONTINUED BELOW NORMAL TEMPERATURES WITH TROUGHING OVER THE CENTRAL US. SUNDAY COULD ACTUALLY BE ONE OF THE WARMER DAYS WITH HIGHS GETTING INTO THE 50S OVER PORTIONS OF THE AREA. STAYED ON THE COOLER SIDE OF GUIDANCE FOR NOW...WITH THE THOUGHT THAT AT LEAST SOME SNOW COVER REMAINS OVER A GOOD PORTION OF THE CWA. BUT IF SNOW IS MAINLY GONE...SUNDAY COULD BE SEVERAL DEGREES WARMER THAN CURRENTLY FORECAST. AS THE THE LONGWAVE TROUGH BUILDS IN...OUR AREA WILL SEE MULTIPLE SHORTWAVES TRAVERSE THE AREA. THUS THE THE THREAT OF RAIN SHOWERS CONTINUE SUNDAY INTO SUNDAY NIGHT. NOT LOOKING AT A LOT OF QPF...BUT MOST PLACES SHOULD GET SOMETHING. COLD FRONT MOVES THROUGH MONDAY INTO MONDAY NIGHT. WITH THE MID LEVEL FRONT THE THREAT OF RAIN SHOWERS WILL CONTINUE. THERMAL PROFILES GET COLD ENOUGH THAT WE COULD SEE SOME SNOW MIX IN LATER MONDAY INTO MONDAY NIGHT...BUT AT THIS TIME WITH THE WAVE MORE PROGRESSIVE...DOES NOT LOOK LIKE WE SEE MUCH IN THE WAY OF ANY ACCUMULATING SNOW...BUT WILL HAVE TO MONITOR MODEL TRENDS. THE SYSTEM MOVES EAST ON TUESDAY...WHICH SHOULD LEAD TO A MAINLY DRY COUPLE DAYS...ALTHOUGH HIGHS WILL BE STUCK IN THE 40S ON TUESDAY WITH THE TROUGH OVERHEAD. A SLOW WARMING TREND SHOULD BEGIN BY WEDNESDAY...WITH HIGHS GETTING INTO THE UPPER 40S TO MID 50S. LONGER RANGE GUIDANCE CONTINUES TO SUGGEST A WARMING TREND LATER NEXT WEEK INTO THE WEEKEND...WITH ACTUAL SPRING LIKE WEATHER POSSIBLY FINALLY ARRIVING. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z FRIDAY MORNING) ISSUED AT 643 AM CDT THU APR 18 2013 SNOW WILL CONTINUE TO INCREASE IN INTENSITY THIS MORNING...WITH CIGS AND VISIBILITIES DROPPING INTO THE IFR CATEGORY. A PERIOD OF HEAVIER SNOW MAY DROP VIS DOWN BELOW A MILE AT TIMES MID MORNING INTO EARLY THIS AFTERNOON...MAINLY ALONG AND EAST OF INTERSTATE 29. THE SNOW WILL TAPER OFF FROM WEST TO EAST THIS EVENING WITH IMPROVING VISIBILITIES. GUSTY NORTHWEST WINDS ARE ALSO EXPECTED TODAY...WITH GUSTS UP TO 40 MPH. SKIES WILL SLOWLY CLEAR FROM WEST TO EAST TONIGHT AS WELL. KEPT MVFR CIGS AT KFSD AND KSUX AS THINK LOW STRATUS WILL STICK AROUND...BUT WILL HAVE TO MONITOR CLEARING TRENDS AS IT MAY CLEAR OUT EARLIER IF ENOUGH LOW LEVEL DRY AIR CAN ADVECT IN. && .FSD WATCHES/WARNINGS/ADVISORIES... SD...WINTER WEATHER ADVISORY UNTIL 1 AM CDT FRIDAY FOR SDZ038-039-050- 052>055-057>061-063>066-068>071. WINTER STORM WARNING UNTIL 1 AM CDT FRIDAY FOR SDZ040-056-062- 067. MN...WINTER WEATHER ADVISORY UNTIL 1 AM CDT FRIDAY FOR MNZ090. WINTER STORM WARNING UNTIL 1 AM CDT FRIDAY FOR MNZ071-072-080- 081-089-097-098. IA...WINTER WEATHER ADVISORY UNTIL 1 AM CDT FRIDAY FOR IAZ002-003- 012>014-020-021-031. WINTER STORM WARNING UNTIL 1 AM CDT FRIDAY FOR IAZ001. NE...WINTER WEATHER ADVISORY UNTIL 1 AM CDT FRIDAY FOR NEZ013-014. && $$ UPDATE...MJF SHORT TERM...08 LONG TERM...CHENARD AVIATION...CHENARD
AREA FORECAST DISCUSSION
NWS SIOUX FALLS SD
649 AM CDT THU APR 18 2013 .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 420 AM CDT THU APR 18 2013 UPPER LEVEL SUPPORT RAPIDLY EXPANDING NORTHWARD THIS MORNING AND WILL MAXIMIZE OVER SOUTHEAST SOUTH DAKOTA INTO NORTHWEST IOWA BY ABOUT 18Z TODAY. INSTABILITY FROM ABOUT 850MB TO 700MB OVER SOUTHEAST NEBRASKA INTO WESTERN IOWA ALLOWING CONVECTIVE ELEMENTS TO DEVELOP IN THOSE AREAS BUT THE INSTABILITY NOT REAL IMPRESSIVE SO NOT THINKING THAT IT WILL PLAY A HUGE ROLE IN THE WEATHER OVER THE NEXT 24 HOURS. DO EXPECT SOME INCREASED RAINFALL RATES IN NORTHWEST IOWA HOWEVER AND THE MAIN CONCERN WILL BE A RIBBON OF FREEZING PRECIPITATION AND SLEET FROM SIOUX CITY TOWARDS SHELDON INTO PARTS OF SOUTHWEST MINNESOTA THROUGH ABOUT LATE MORNING. FARTHER WEST IT SHOULD BE MAINLY SNOW AND A BAND OF HEAVY SNOWFALL STILL LOOKS GOOD FROM YANKTON TO SIOUX FALLS INTO SOUTHWEST MINNESOTA. UPPER LEVEL PV ADVECTION MAXIMIZES THIS MORNING AND THE 750MB TO 650MB FRONT IS PLANTED RIGHT OVER SOUTHEAST SOUTH DAKOTA INTO SOUTHWEST MINNESOTA. WHILE THERE IS SOME INSTABILITY ABOVE THE FRONT IT IS NOT NEARLY AS IMPRESSIVE AS LAST WEEKS SYSTEM. SO AT THIS TIME NOT PLANNING ON ANY THUNDER SNOW BUT SNOWFALL RATES OF AN INCH AN HOUR AT TIMES STILL LIKELY. THE BEST CHANCE FOR THE HEAVIEST SNOWFALL RATES WILL BE FROM ABOUT 12Z THROUGH 19Z SHIFTING FROM FROM SOUTH TO NORTH. STILL EXPECT SNOW TO CONTINUE THROUGH THE REMAINDER OF THE AFTERNOON AND EVENING...DECREASING PRETTY QUICKLY FOR THE WEST TONIGHT. THE 21Z SREF HAS PRETTY GOOD CLUSTERING AROUND 8 TENTHS OF AN INCH OF LIQUID AROUND SIOUX FALLS WHILE THE LATEST GEM/ECMWF/NAM ARE CLOSER TO 6 TO 7 TENTHS OF LIQUID. THE 3Z SREF HAS DROPPED OFF QUITE A BIT WITH STORM TOTAL LIQUID AFTER 12Z THIS MORNING ABOUT 0.45...THIS TAKING AWAY THE 0.13 IT HAD IN BEFORE 12Z WHICH DOES NOT LOOK LIKE IT WILL OCCUR. IN FACT MOST AREAS WEST OF A YANKTON TO SLAYTON LINE LIKELY WILL GET ONLY A COUPLE OF TENTHS OR LESS THROUGH 12Z THIS MORNING WITH MAYBE AN INCH OR SO FROM THE JAMES VALLEY WEST. TAKING THIS INTO ACCOUNT WITH ALL OF THE MODELS LOOKS LIKE WE WILL SETTLE IN TO MORE OF A 4 TO 6 TENTHS LIQUID POTENTIAL. GIVEN SOME COMPACTION AND MELTING AS IT FALLS 4 TO 6 INCHES SEEMS ABOUT RIGHT FOR THE SIOUX FALLS AREA WITH AN INCH OR TWO MORE IN SOUTHWEST MINNESOTA. A LITTLE WORRIED THAT THE SNOWFALL FALLING DURING THE DAY VERSUS AT NIGHT LIKE LAST WEEK AND LESS INSTABILITY THAN THAT SYSTEM AS WELL AS SURFACE TEMPERATURES ABOUT 2-3 DEGREES WARMER WILL KEEP AMOUNTS ABOUT 4-5 INCHES. LATEST RUNS OF THE HRRR AS WELL AS THE RAP KEEP THE BETTER AMOUNTS JUST EAST AND NORTH OF THE INTERSTATE 29 CORRIDOR WHICH MATCHES FAIRLY WELL WITH THE MID LEVEL BOUNDARY...AROUND 700MB AND THE EDGE OF THE DRY SLOT. .LONG TERM...(FRIDAY THROUGH WEDNESDAY) ISSUED AT 420 AM CDT THU APR 18 2013 FRIDAY AND SATURDAY WILL CONTINUE TO SEE BELOW NORMAL TEMPERATURES ESPECIALLY WITH THE SNOW COVER. ANOTHER SYSTEM WILL BRING THE CHANCE FOR RAIN OR SNOW TO THE AREA SATURDAY AND SATURDAY NIGHT BUT IS NOT EXPECTED TO BE A MAJOR IMPACT. THE SUNDAY INTO MIDDLE OF NEXT WEEK PERIOD IS CHARACTERIZED BY CONTINUED BELOW NORMAL TEMPERATURES WITH TROUGHING OVER THE CENTRAL US. SUNDAY COULD ACTUALLY BE ONE OF THE WARMER DAYS WITH HIGHS GETTING INTO THE 50S OVER PORTIONS OF THE AREA. STAYED ON THE COOLER SIDE OF GUIDANCE FOR NOW...WITH THE THOUGHT THAT AT LEAST SOME SNOW COVER REMAINS OVER A GOOD PORTION OF THE CWA. BUT IF SNOW IS MAINLY GONE...SUNDAY COULD BE SEVERAL DEGREES WARMER THAN CURRENTLY FORECAST. AS THE THE LONGWAVE TROUGH BUILDS IN...OUR AREA WILL SEE MULTIPLE SHORTWAVES TRAVERSE THE AREA. THUS THE THE THREAT OF RAIN SHOWERS CONTINUE SUNDAY INTO SUNDAY NIGHT. NOT LOOKING AT A LOT OF QPF...BUT MOST PLACES SHOULD GET SOMETHING. COLD FRONT MOVES THROUGH MONDAY INTO MONDAY NIGHT. WITH THE MID LEVEL FRONT THE THREAT OF RAIN SHOWERS WILL CONTINUE. THERMAL PROFILES GET COLD ENOUGH THAT WE COULD SEE SOME SNOW MIX IN LATER MONDAY INTO MONDAY NIGHT...BUT AT THIS TIME WITH THE WAVE MORE PROGRESSIVE...DOES NOT LOOK LIKE WE SEE MUCH IN THE WAY OF ANY ACCUMULATING SNOW...BUT WILL HAVE TO MONITOR MODEL TRENDS. THE SYSTEM MOVES EAST ON TUESDAY...WHICH SHOULD LEAD TO A MAINLY DRY COUPLE DAYS...ALTHOUGH HIGHS WILL BE STUCK IN THE 40S ON TUESDAY WITH THE TROUGH OVERHEAD. A SLOW WARMING TREND SHOULD BEGIN BY WEDNESDAY...WITH HIGHS GETTING INTO THE UPPER 40S TO MID 50S. LONGER RANGE GUIDANCE CONTINUES TO SUGGEST A WARMING TREND LATER NEXT WEEK INTO THE WEEKEND...WITH ACTUAL SPRING LIKE WEATHER POSSIBLY FINALLY ARRIVING. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z FRIDAY MORNING) ISSUED AT 643 AM CDT THU APR 18 2013 SNOW WILL CONTINUE TO INCREASE IN INTENSITY THIS MORNING...WITH CIGS AND VISIBILITIES DROPPING INTO THE IFR CATEGORY. A PERIOD OF HEAVIER SNOW MAY DROP VIS DOWN BELOW A MILE AT TIMES MID MORNING INTO EARLY THIS AFTERNOON...MAINLY ALONG AND EAST OF INTERSTATE 29. THE SNOW WILL TAPER OFF FROM WEST TO EAST THIS EVENING WITH IMPROVING VISIBILITIES. GUSTY NORTHWEST WINDS ARE ALSO EXPECTED TODAY...WITH GUSTS UP TO 40 MPH. SKIES WILL SLOWLY CLEAR FROM WEST TO EAST TONIGHT AS WELL. KEPT MVFR CIGS AT KFSD AND KSUX AS THINK LOW STRATUS WILL STICK AROUND...BUT WILL HAVE TO MONITOR CLEARING TRENDS AS IT MAY CLEAR OUT EARLIER IF ENOUGH LOW LEVEL DRY AIR CAN ADVECT IN. && .FSD WATCHES/WARNINGS/ADVISORIES... SD...WINTER WEATHER ADVISORY UNTIL 1 AM CDT FRIDAY FOR SDZ038-039-050- 052>055-057>061-063>066-068>071. WINTER STORM WARNING UNTIL 1 AM CDT FRIDAY FOR SDZ040-056-062- 067. MN...WINTER WEATHER ADVISORY UNTIL 1 AM CDT FRIDAY FOR MNZ090. WINTER STORM WARNING UNTIL 1 AM CDT FRIDAY FOR MNZ071-072-080- 081-089-097-098. IA...WINTER WEATHER ADVISORY UNTIL 1 AM CDT FRIDAY FOR IAZ002-003- 012>014-020-021-031. WINTER STORM WARNING UNTIL 1 AM CDT FRIDAY FOR IAZ001. NE...WINTER WEATHER ADVISORY UNTIL 1 AM CDT FRIDAY FOR NEZ013-014. && $$ SHORT TERM...08 LONG TERM...CHENARD AVIATION...CHENARD
AREA FORECAST DISCUSSION
NWS NASHVILLE TN
1227 PM CDT THU APR 18 2013 .AVIATION 18Z DISCUSSION... OTHER THAN BREEZY CONDITIONS THIS AFTERNOON...ALL EYES ARE ON THE APPROACHING WEATHER SYSTEM TO OUR WEST. A LINE OF SHOWERS AND POTENTIALLY SEVERE THUNDERSTORMS ARE EXPECTED TO ROAR THROUGH THE MID STATE OVERNIGHT. WINDS OFF THE SFC ARE STRONG ENOUGH TO WARRANT LLWS VALUES OF 45-55KTS BETWEEN 22Z AND 09Z. SFC WINDS WILL FOR THE MOST PART GUST UP TO 40-45 KTS WITH THE LINE(S) OF STORMS THAT MOVES THROUGH. SOME PRE FRONTAL ACTIVITY IS ALSO POSSIBLE AND DUAL LINES COULD FORM. A BRIEF WINDOW OF LIGHT SHOWER ACTIVITY WILL FOLLOW THE STORMS. PRECIP FREE CONDITIONS FOR CKV AND BNA ONLY...AFT 14Z....BUT BKN CIG OF 3-5 KFT TO REMAIN. && .PREV DISCUSSION... /ISSUED 617 AM CDT THU APR 18 2013/ UPDATE...FOR 12Z AVIATION FORECAST AVIATION... STRONG LINE OF CONVECTION FROM CHICAGO DOWN THROUGH SAINT LOUIS INTO FAR EASTERN OKLAHOMA AND EASTERN TEXAS WILL MOVE EAST TODAY AND BE ALONG THE MISSISSIPPII RIVER BY 23Z AND ALONG THE TENNESSEE RIVER BY 02Z AND INTERSTATE 65 AT 05Z AND ON THE PLATEAU BY 11Z. LOW LEVEL JET OUT AHEAD OF THE LINE ON THE ORDER OF 65 TO 70 KNOTS WILL PULL EAST WITH THE LINE TODAY AND TONIGHT. BOUNDARY LAYER WINDS ALREADY 45 KNOTS AT BNA THIS MORNING WILL LIKELY SUSTAIN THIS SPEED DURING THE DAY AND EVENING WITH SURFACE WINDS GUSTS TO 30 KNOTS DURING THE DAY AND INTO THE EVENING ACROSS THE MID STATE. WILL INCLUDE LOW LEVEL WIND SHEAR FOR THIS MORNING AT ALL TERMINALS. STRONG CAPPING INVERSION BASED AROUND 825 MBARS WILL PRECLUDE ANY THUNDERSTORM DEVELOPMENT UNTIL TONIGHT. ONCE SQUALL LINE PASSES TONIGHT LOOK FOR GUSTY WEST WINDS TO FOLLOW. BOYD PREV DISCUSSION... /ISSUED 400 AM CDT THU APR 18 2013/ .MODERATE RISK OF SEVERE THUNDERSTORMS THIS EVENING INTO TONIGHT... DISCUSSION... FEW OVERALL CHANGES TO THE FORECAST OVER THE NEXT WEEK...WITH MAINLY SLIGHT ADJUSTMENTS TO TEMPS AND TIMING OF PRECIP. A LARGE H5 TROUGH OVER THE PLAINS STATES WILL SHIFT INTO THE MISSISSIPPI VALLEY TODAY THEN ACROSS THE TENNESSEE VALLEY TONIGHT...WITH AN ASSOCIATED STRONG COLD FRONT SWEEPING THROUGH THE MID STATE TONIGHT. BEFORE THE FRONT ARRIVES...ANOTHER SUMMER-LIKE DAY IS ON TAP WITH TEMPERATURES STARTING OUT IN THE 60S TO AROUND 70 THIS MORNING THEN WARMING UP INTO THE LOW TO MID 80S AREAWIDE THIS AFTERNOON. AS A SUB-1000MB SURFACE LOW TAKES SHAPE ACROSS THE MIDWEST...925MB WINDS WILL INCREASE ACROSS OUR REGION INTO THE 40-50KT RANGE TODAY LEADING TO GUSTY SOUTH WINDS AT THE SURFACE. ANTICIPATING SOUTH WINDS IN THE 15 TO 30 MPH RANGE DEVELOPING LATER THIS MORNING...THEN CONTINUING INTO THE AFTERNOON HOURS BEFORE SUBSIDING SOMEWHAT EARLY IN THE EVENING. OCCASIONAL GUSTS TO NEAR 40 MPH APPEAR LIKELY AS WELL BASED ON BUFKIT SOUNDINGS. SOUTH WINDS WILL INCREASE AGAIN LATER IN THE EVENING AS A SHARP PRESSURE GRADIENT MOVES ACROSS THE MID STATE AHEAD OF THE COLD FRONT. TO SIMPLIFY MATTERS...HAVE ISSUED A WIND ADVISORY FOR ALL ZONES BEGINNING LATER THIS MORNING AND CONTINUING THROUGH THE EARLY MORNING HOURS ON FRIDAY. SPC HAS PLACED AREAS ALONG AND WEST OF THE I-65 CORRIDOR IN A MODERATE RISK FOR SEVERE STORMS THURSDAY EVENING WITH A SLIGHT RISK TO THE EAST THURSDAY NIGHT. 00Z GFS/NAM/ECMWF AND LATEST HIGH RESOLUTION 4.0 KM WRF...NSSL WRF...AND HRRR ALL INDICATE A STRONG TO SEVERE QLCS WILL FORM LATER TODAY ALONG THE FRONT...REACHING THE TENNESSEE RIVER BY MID EVENING...I-65 CORRIDOR AROUND MIDNIGHT...AND EXIT EAST OF THE CWA NEAR/AFTER SUNRISE FRIDAY MORNING. MODELS CONTINUE TO DEPICT GENERALLY WEAK INSTABILITY AROUND 500 J/KG AHEAD OF THE LINE...BUT SOME GUIDANCE INDICATES A SURGE OF MID/UPPER 60S DEWPOINTS COMING NORTHWARD AHEAD OF THE QLCS WHICH COULD BUMP UP CAPE VALUES TO NEAR/OVER 1000 J/KG ACROSS WESTERN ZONES. REGARDLESS...IMPRESSIVE 0-3KM SRH STRENGTHENING INTO THE 500-800 M2/S2 RANGE AND VERY LONG CURVED HODOGRAPHS SUGGESTS A SIGNIFICANT DAMAGING WIND THREAT WITH THE LINE OF STORMS ALONG WITH SOME QLCS TORNADOES. HIGHEST RISK OF DAMAGING WINDS/TORNADOES IS EXPECTED TO BE ALONG/WEST OF I-65 IN THE 02-06Z TIMEFRAME ACROSS THE MODERATE RISK AREA...AS STORMS WILL ENCOUNTER INCREASINGLY LESS INSTABILITY AND WEAKENING SHEAR OFF TO THE EAST. STRATIFORM RAIN AND A FEW THUNDERSTORMS WILL CONTINUE MUCH OF THE NIGHT BEHIND THE QLCS WITH RAINFALL COMING TO AN END FROM WEST TO EAST FRIDAY MORNING. MUCH COOLER TEMPERATURES ARE ANTICIPATED FRIDAY AND SATURDAY WITH LOWS FALLING INTO THE MID TO UPPER 30S SATURDAY MORNING. WITH SURFACE RIDGE SETTLING OVER THE MID STATE...LIGHT TO CALM WINDS...AND DEWPOINTS FALLING INTO THE 20S AND 30S...PATCHY FROST APPEARS POSSIBLE FOR MUCH OF THE FORECAST AREA AND HAVE ADDED MENTION TO ZONES. AREA WILL BEGIN TO WARMUP FROM SUNDAY INTO EARLY NEXT WEEK AS SOUTHERLY FLOW BEGINS ANEW. FEW CHANGES WERE MADE IN THE EXTENDED FORECAST WITH NEXT CHANCE FOR RAIN AROUND TUESDAY/WEDNESDAY OF NEXT WEEK. && .OHX WATCHES/WARNINGS/ADVISORIES... WIND ADVISORY UNTIL 1 AM CDT FRIDAY FOR TNZ005>011-022>034- 056>066-075-077>080-093>095. && $$ 21
AREA FORECAST DISCUSSION...UPDATED
NWS MILWAUKEE/SULLIVAN WI
1230 PM CDT THU APR 18 2013 .UPDATE...AREA OF RAIN HAS PUSHED OUT OF THE AREA...AS LOW LEVEL JET FORCING HAS SHIFTED TO THE EAST. HRRR AND 4KM WRF/NMM HAVE HANDLED THIS WELL...AND SHOW A LINE OF SHOWERS AND A FEW THUNDERSTORMS SHIFTING NORTHEAST THROUGH THE AREA FROM MID TO LATE AFTERNOON/EARLY EVENING. THIS IS IN RESPONSE TO SURFACE LOW AND COLD FRONT MOVING NORTHEAST THROUGH THE AREA. THUS...ADJUSTED FORECAST FOR DRIZZLE UNTIL THESE SHOWERS AND ISOLATED STORMS PUSH THROUGH. THIS WILL BE THE LAST ROUND OF RAINFALL ACROSS THE AREA...SO HAVE PUSHED UP THE ENDING TIME OF THE AREAL FLOOD WATCH TO 9 PM THIS EVENING. THERE WILL OBVIOUSLY STILL BE FLOODING PROBLEMS NEAR AREA RIVERS FOR AWHILE...AND SOME FLOODING IN LOW LYING AREAS. HOWEVER...THE RISK FOR MORE AREAL FLOODING SHOULD SUBSIDE AFTER THIS LAST ROUND OF PRECIPITATION EXITS THE AREA EARLY THIS EVENING. ADJUSTED HIGHS DOWN A BIT...AS LOW PUSHING WARMER AIR NORTHWARD TOWARD THE FAR SOUTHERN PORTIONS OF THE AREA WILL BATTLE COOLER AIR WITH CLOUDS AND ANY PRECIPITATION AREAS. && .AVIATION/18Z TAFS/...CEILINGS BETWEEN ALTERNATE MINIMUMS AND AIRPORT MINIMUMS WILL PERSIST ACROSS TAF SITES THIS AFTERNOON AND INTO TONIGHT. VISIBILITIES SHOULD REMAIN MAINLY VFR THIS AFTERNOON AND TONIGHT. LINE OF SHOWERS AND ISOLATED THUNDERSTORMS ARE EXPECTED TO MOVE NORTHEAST THROUGH TAF SITES BETWEEN 21Z THURSDAY AND 01Z FRIDAY. MAY SEE VISIBILITIES DOWN TO NEAR ALTERNATE MINIMUMS WITH THE PRECIPITATION. LIGHT WINDS THIS AFTERNOON WILL SHIFT SOUTHWEST AFTER THE LOW PRESSURE SYSTEM PASSES NORTHEAST THROUGH THE AREA EARLY THIS EVENING. THESE WINDS WILL QUICKLY BECOME GUSTY BY LATE EVENING AND LINGER OVERNIGHT. THEY WILL VEER WEST ON FRIDAY AND REMAIN GUSTY. SUSTAINED WINDS TO 23 KNOTS...AND GUSTS TO 35 KNOTS...ARE POSSIBLE AT TIMES LATE TONIGHT AND FRIDAY. SHOULD SEE SCATTERED LIGHT SNOW SHOWERS BETWEEN 10Z AND 14Z FRIDAY AT MADISON. ANY ACCUMULATIONS WILL BE LIMITED TO A DUSTING AT WORST ON GRASSY AREAS...WITH THE RUNWAYS JUST REMAINING WET. THIS SHOULD CHANGE TO SCATTERED RAIN SHOWERS BY MID MORNING AND LINGER THROUGH THE REST OF THE DAY. THE EASTERN SITES SHOULD SEE SCATTERED RAIN SHOWERS THROUGH THE DAY. && .MARINE...ISSUED A SMALL CRAFT ADVISORY FROM 10 PM THIS EVENING UNTIL 2 AM FRIDAY MORNING...AND A GALE WARNING FROM 2 AM FRIDAY MORNING UNTIL 7 PM FRIDAY EVENING. LOW PRESSURE WILL STRENGTHEN AS IT SHIFTS NORTHEASTWARD THROUGH THE REGION TONIGHT AND FRIDAY. THIS WILL ALLOW FOR GUSTY SOUTHWEST WINDS TO DEVELOP OVER THE NEARSHORE WATERS THIS EVENING. THESE WINDS WILL INCREASE IN MAGNITUDE LATER TONIGHT INTO FRIDAY...VEERING TO THE WEST. FREQUENT GUSTS TO 35 KNOTS ARE EXPECTED DURING THIS TIME. HIGH WAVES WILL OCCUR TOWARD THE OPEN WATERS...WITH THE OFFSHORE FLOW. && .PREV DISCUSSION... /ISSUED 500 AM CDT THU APR 18 2013/ SHORT TERM... TODAY AND TONIGHT...FORECAST CONFIDENCE MEDIUM BEST ELEVATED INSTABILITY AND HEAVIEST RAINFALL HAS STAYED OVER IL DURING THE OVERNIGHT AND EXPECT THIS SCENARIO TO CONTINUE AS THE 50-60 KT LLJ LIFTS NEWD FROM IL INTO MI. THE INVERTED TROUGH OVER ERN IA AND WRN WI WILL SHIFT EAST ACROSS SRN WI THIS AM AND THEN ANOTHER ROUND OF CYCLOGENESIS OVER NRN IL OR SRN WI AS THE UPPER TROUGH APPROACHES FROM THE PLAINS. THE LOW WILL DEEPEN THE MOST AFTER IT LIFTS TO THE NE TOWARD THE NRN GREAT LAKES. A LARGE DRY SLOT WILL THEN FOLLOW FOR TNT WITH LITTLE ADDITIONAL PCPN. THE UPPER TROUGH AXIS WILL THEN APPROACH THE WRN CWA BY FRI AM WITH INCREASED SATURATION AND BETTER CHANCES OF LIGHT SNOW. ADDITIONAL RAINFALL AMOUNTS FOR TODAY WILL RANGE FROM 0.40 INCHES IN THE FAR NW CWA TO JUST UNDER AN INCH IN SE WI. OVERALL THE NRN CWA HAS ESCAPED THE HEAVY RAINS...SO ANY RIVERS THAT HAVE THEIR HEADWATERS IN THIS AREA WILL NOT FLOOD AS BADLY AS FIRST THOUGHT. NEW RIVER FORECASTS THAT INCLUDE THE LESSER RAIN TOTALS WILL BE ISSUED LATER THIS MORNING. FRIDAY...FORECAST CONFIDENCE MEDIUM TO HIGH. SURFACE LOW PRESSURE CENTERED OVER CENTRAL UPPER MICHIGAN WILL GRADUALLY SHIFT INTO EASTERN ONTARIO LATE IN THE DAY. THE SLOW MOVEMENT IS IN RESPONSE TO THE UPPER LOW CLOSING OFF AND BECOMING NEGATIVELY TILTED OVER LAKE SUPERIOR...AND THE SURFACE LOW OCCLUDING. COLD AIR WILL SLOWLY MOVE INTO SOUTHERN WI ON THE BACK SIDE OF THIS SYSTEM. THE PRECIP SHIELD WITHIN THE DEFORMATION ZONE WILL BE QUITE EXPANSIVE. MODELS SHOW STRONG 700-300MB Q-VECTOR CONVERGENCE OVER MUCH OF WI FRIDAY MORNING...ALONG WITH STEEP LOW LEVEL LAPSE RATES AND CYCLONIC FLOW ALOFT. FORECAST TEMPERATURE PROFILES SHOW A SHALLOW LAYER RIGHT AROUND FREEZING AT THE GROUND...BUT BELOW FREEZING TEMPS JUST ABOVE ON FRIDAY MORNING. THE NAM IS COLDER THAN THE GFS AND ECMWF. MOISTURE WILL BE SHALLOW...SO IT IS POSSIBLE THAT WE SEE DRIZZLE INSTEAD OF RAIN OR SNOW FOR SOME OF THE TIME. ONLY A LIGHT DUSTING OF SNOW AT BEST FOR THE WEST HALF OF THE FORECAST AREA. BY MIDDAY FRIDAY...SURFACE TEMPS WILL BE ABOVE FREEZING...AND ANY MIXED PRECIP WILL TRANSITION BACK TO RAIN. IT WILL BE A CHILLY DAY WITH HIGHS ONLY IN THE UPPER 30S AND LOWER 40S. ANOTHER CONCERN FOR FRIDAY WILL BE THE GUSTY WEST WINDS DUE TO THE TIGHT PRESSURE GRADIENT OVERHEAD. GUSTS UP TO 35 MPH WILL BE LIKELY WITH EFFICIENT MIXING OF HIGHER WINDS AT AROUND 5000 FEET DOWN TO THE SURFACE. SUSTAINED WINDS UP TO 25 MPH WITH GUSTS OVER 35 MPH ARE LIKELY. EXPECTING WINDS TO REMAIN BELOW WIND ADVISORY CRITERIA...BUT IT WILL BE CLOSE. PRECIP CHANCES TAPER OFF SIGNIFICANTLY EARLY FRIDAY EVENING WITH LOSS OF DAYTIME HEATING/INSTABILITY...AS DRY AIR AND HIGH PRESSURE MOVE INTO THE REGION. LONG TERM... SATURDAY AND SUNDAY...FORECAST CONFIDENCE MEDIUM TO HIGH. SURFACE HIGH PRESSURE AND UPPER LEVEL RIDGING WILL DRIFT OVERHEAD ON SATURDAY...BRINGING LIGHT WINDS AND SUNSHINE. A LAKE BREEZE IS EXPECTED BY EARLY SATURDAY AFTERNOON. MAX TEMPS WILL ONLY REACH THE MID 40S NEAR THE LAKE...BUT UPPER 40S WELL INLAND. CLOUDS WILL BEGIN TO MOVE IN SAT NIGHT AND OVERSPREAD THE AREA ON SUNDAY AS LOW PRESSURE APPROACHES FROM THE PLAINS. ISENTROPIC LIFT AND WEAK WARM AIR ADVECTION WILL BRING LIGHT RAIN CHANCES TO SOUTH CENTRAL WI ON SUNDAY. BEST CHANCE FOR PRECIP WILL BE INLAND FROM THE LAKE SINCE THERE WILL BE QUITE A BIT OF DRY AIR ON EASTERLY WINDS EATING AWAY AT IT. GFS SHOWS PRECIP CHANCES FOR SOUTHERN WI SUN NIGHT/MON MORNING WHILE THE ECMWF IS DRY. MONDAY THROUGH WEDNESDAY...FORECAST CONFIDENCE MEDIUM. AN UPPER TROUGH WILL DEVELOP AND BECOME MORE AMPLIFIED DURING THE FIRST HALF OF THE WEEK OVER THE CENTRAL US. SEVERAL SHORTWAVES WILL MOVE THROUGH WI AHEAD OF THIS UPPER TROUGH AND BRING MORE ROUNDS OF RAIN TO THE REGION. THE BEST CHANCE FOR RAIN LOOKS LIKE MONDAY NIGHT THROUGH TUESDAY MORNING. RAIN MAY TRANSITION TO SNOW BY TUE NIGHT. IT ONLY LOOKS LIKE MINOR SNOW AMOUNTS AT THIS TIME. AVIATION/12Z TAFS/...ROUNDS OF SHOWERS AND ISOLATED THUNDERSTORMS WILL CONTINUE TODAY AS LOW PRESSURE MOVES ACROSS THE REGION. IFR CIGS OR LESS WILL PREVAIL WITH VSBYS MAINLY RANGING FROM 2-5 MILES. SWLY WINDS AND A DRY SLOT WILL REDUCE THE CHANCES FOR RAIN AND IMPROVE THE VSBYS. CIGS WILL SLOWLY RISE TO 1.0-2.0 KFT. MARINE...A GALE WATCH IS IN EFFECT LATE TONIGHT AND FRIDAY AS SOUTHWEST TO WEST WINDS INCREASE DUE TO STRONG LOW PRESSURE OVER THE NORTHERN GREAT LAKES. WEST WINDS UP TO 20 TO 25 KNOTS AND GUSTS TO 35 KNOTS ARE EXPECTED. HIGH WAVES WILL OCCUR TOWARD THE OPEN WATERS OF LAKE MI. && .MKX WATCHES/WARNINGS/ADVISORIES... WI...FLOOD WATCH UNTIL 9 PM CDT THIS EVENING FOR WIZ046-047-051-052- 056>060-062>072. LM...SMALL CRAFT ADVISORY FROM 10 PM THIS EVENING TO 2 AM CDT FRIDAY FOR LMZ643>646. GALE WARNING FROM 2 AM TO 7 PM CDT FRIDAY FOR LMZ643>646. && $$ UPDATE...WOOD TODAY/TONIGHT AND AVIATION/MARINE...GEHRING FRIDAY THROUGH WEDNESDAY...MRC