Forecast Discussions mentioning any of "HRRR" "RAP" "RR" "RUC13" "RUC" received at GSD on 04/20/13


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. && $$ SYNOPSIS...ROBERTSON/DRAG 854 NEAR TERM...DRAG/NIERENBERG 854 SHORT TERM...DRAG/NIERENBERG 854 LONG TERM...ROBERTSON AVIATION...DRAG/ROBERTSON 854 MARINE...DRAG/NIERENBERG/ROBERTSON 854
AREA FORECAST DISCUSSION
NWS MIAMI FL
138 PM EDT FRI APR 19 2013 .AVIATION... VFR CONDITIONS ARE EXPECTED THROUGH THE OVERNIGHT PERIOD. TOMORROW MORNING, SOME MVFR CIGS MAY MOVE INTO SOUTH FLORIDA, AHEAD OF A COLD FRONT. FOR TODAY, ISOLATED TO SCATTERED SHOWERS ARE POSSIBLE, BUT MAINLY IN THE INTERIOR, AND NOT EXPECTED TO SIGNIFICANTLY AFFECT THE TAF SITES TODAY. THESE SHOULD DIMINISH THIS EVENING. THEN TOMORROW, THERE IS AN INCREASING CHANCE OF SHOWERS AND POSSIBLY THUNDERSTORMS THROUGH THE DAY. WINDS TODAY, WILL CONTINUE OUT OF THE SE WITH SOME GUSTS TO AROUND 25 KTS POSSIBLE. THEY WILL WEAKEN SOME TONIGHT, AND THEN BECOME SOMEWHAT MORE SOUTHERLY TOMORROW AS THE FRONT APPROACHES. && .PREV DISCUSSION... /ISSUED 1009 AM EDT FRI APR 19 2013/ UPDATE... A FEW LIGHT SHOWERS CONTINUE TO PUSH ONSHORE THE ATLANTIC COAST UNDER SOUTHEAST FLOW. THESE SHOWERS ARE VERY LIGHT AND WILL CONTINUE TO PUSH NORTHWEST ACROSS BROWARD AND MIAMI-DADE COUNTIES THROUGH THE MORNING. LATEST HRRR INITIALIZED WELL AND KEEPS THESE SHOWERS AND POSSIBLY A FEW THUNDERSTORMS ACROSS NORTHERN INTERIOR AREAS THROUGH THE AFTERNOON. INCREASED POPS SLIGHTLY ACROSS THE EAST COAST AND ADJUSTED TEMPERATURES TO ACCOUNT FOR CURRENT TRENDS...OTHERWISE CURRENT FORECAST IS ON TRACK. UPDATE SENT. && .PRELIMINARY POINT TEMPS/POPS... WEST PALM BEACH 74 83 71 84 / 30 50 40 60 FORT LAUDERDALE 76 86 74 85 / 30 50 30 60 MIAMI 75 87 73 84 / 30 50 30 50 NAPLES 72 87 69 86 / 30 40 30 50 && .MFL WATCHES/WARNINGS/ADVISORIES... FL...NONE. AM...NONE. GM...NONE. && $$ DISCUSSION/MARINE/FIRE...10/CD AVIATION/RADAR...13/SI
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 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 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 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 DULUTH MN
645 PM CDT FRI APR 19 2013 .UPDATE... RADAR SHOWS COVERAGE OF THE SNOW SHOWERS WERE DIMINISHING ACROSS THE ARROWHEAD AND EXTREME NORTHWEST WISCONSIN...AND VSBYS CONFIRM WITH KCKC UP TO 1.5SM. WE MAY BE ABLE TO CANCEL THE WARNINGS IN THE ARROWHEAD EARLY. GRAVITY WAVED INDUCED AREA OF SNOW SHOWERS ALSO SEEMS TO BE DIMINISHING...AND A CROSS SECTION THROUGH THAT AREA FROM THE RAP INDICATED CONDITIONS BECOMING LESS FAVORABLE AS DRIER AIR MOVES IN. WE MAY ALSO DROP THE WARNING ACROSS DOUGLAS COUNTY EARLY IF CURRENT TRENDS CONDITIONS. STRONG WINDS AND A FAVORABLE SET UP FOR LAKE EFFECT SNOW WILL KEEP SNOW SHOWERS GOING LONGER ACROSS PORTIONS OF BAYFIELD...BUT ESPECIALLY ASHLAND AND IRON COUNTIES. STRONG WINDS WERE ALSO CREATING ISSUES WITH BLOWING/DRIFTING. WE EXPECT THE WINDS TO DIMINISH AS THE EVENING PROGRESSES. && .AVIATION...00Z TAFS CLOUDS WERE DIMINISHING THIS EVENING OVER MINNESOTA...WITH THE SNOW SHOWERS ALSO DIMINISHING IN COVERAGE OVER NORTHEAST MINNESOTA AND EXTREME NORTHWEST WISCONSIN. WE EXPECT THE TAF SITES TO BECOME VFR THIS EVENING...WITH THE WIND DIMINISHING OVER THE NEXT 1-3 HOURS. MVFR TO LIFR CONDITIONS WILL CONTINUE THROUGH MOST OF THE EVENING ACROSS THE SNOWBELT OF THE SOUTH SHORE. VFR CONDITIONS WILL PREVAIL THROUGH THE DAY SATURDAY...WITH SOME SCATTERED TO PERHAPS BROKEN CUMULUS DEVELOPING BY AFTERNOON. && .PREV DISCUSSION... /ISSUED 347 PM CDT FRI APR 19 2013/ SHORT TERM...TONIGHT THROUGH SATURDAY... THE POWERFUL WINTER STORM THAT BROUGHT 1 TO 2 FEET OF SNOW TO MUCH OF THE NORTHLAND OVER THE LAST 1-2 DAYS WILL CONTINUE TO GRADUALLY WIND DOWN ACROSS THE REGION OVERNIGHT. HEAVY SNOW CONTINUED ACROSS THE ARROWHEAD...AND LOCALLY ACROSS THE SOUTH SHORE OF LAKE SUPERIOR. COOK COUNTY CONTINUES TO HAVE A TOUGH TIME KEEPING ROADS CLEARED WITH HEAVY SNOW AND INTENSE WINDS OF 40 TO 50 MPH AT TIMES. IT APPEARS THE STANDING WAVE SHOWING UP ON 88D RADAR EXTENDS NORTHWARD INTO COOK COUNTY WITH VISIBILITIES OF A QUARTER MILE OR LESS AT TIMES. ACROSS THE SOUTH SHORE...LOCALLY HEAVY SNOW SHOWERS CONTINUED ACROSS THAT AREA AS WELL. LOOKING FOR ANOTHER GOOD 1 TO 3 INCHES IN THE ARROWHEAD AND LOCALLY UP TO ANOTHER 6 INCHES FOR THE SOUTH SHORE OF LAKE SUPERIOR. HIGH PRESSURE WILL BUILD EASTWARD ACROSS THE NORTHLAND OVERNIGHT...BRINGING A GRADUAL END TO THE SNOW FROM WEST TO EAST. SOME CLEARING HAD ALREADY TAKEN PLACE IN THE WESTERN PORTION OF THE CWA. THIS CLEARING WILL SET THE STAGE FOR SOME POTENTIALLY RECORD BREAKING COLD TEMPERATURES BY SATURDAY MORNING. LOWS SHOULD RANGE FROM THE SINGLE DIGITS TO THE TEENS DUE TO CLEARING SKIES...DRIER AIR AND A SOLID SNOW PACK THAT IS QUITE UNUSUAL FOR THIS TIME OF YEAR. THERE SHOULD BE PLENTY OF SUNSHINE ON SATURDAY WITH TEMPERATURES IN THE 30S FOR DAYTIME HIGHS...WELL BELOW OUR NORMAL HIGH AROUND THE 50 DEGREE MARK. LONG TERM...SATURDAY NIGHT THROUGH FRIDAY... THE NEXT STORM SYSTEM WILL BE AFFECTING THE FORECAST AREA. THE MODELS ARE DIFFERENT IN THEIR SOLUTIONS WITH THE MOVEMENT OF THE LOW PRESSURE CENTER. THE NAM AND GFS HAS THE CENTER IN SOUTHERN CANADA WITH A TROUGH ACROSS THE FORECAST AREA. THE ECMWF AND GEM HAS THE CENTER MOVING ACROSS THE BORDER. PRECIP MOVES INTO THE SOUTHERN PORTIONS OF THE FORECAST AREA SUNDAY MORNING AND SPREADS NORTH. THE PTYPE WILL BE SNOW THIS MORNING AND SWITCH OVER TO RAIN BY MIDDAY. THE LOW MOVES EAST BY MONDAY MORNING ENDING THE MAIN PART OF PRECIP WEST TO EAST SUNDAY NIGHT. THERE WILL BE A BREAK BEFORE THE NEXT STORM SYSTEM AFFECT THE REGION MONDAY NIGHT. MODELS INDICATE THE PRECIP WILL BE MAINLY CONFINED TO NW WI. THE QUESTION FOR THIS SYSTEM IS IF THE RAIN/SNOW SPREADS INTO DULUTH. RIGHT NOW...WE WILL KEEP IT MAINLY SOUTH OF THE TWIN PORTS. THE PROBLEMS WITH THE TWO SYSTEM WILL BE THE PRECIP AMOUNTS OF 0.33 TO 0.75 INCHES WHICH WILL ADD ADDITIONAL MOISTURE TO THE SNOW PACK. THERE WILL BE A WARMUP NEXT WEEK WITH TEMPS INTO THE 40S WHICH START THE SNOWMELT. && .POINT TEMPS/POPS... DLH 13 36 24 40 / 30 0 50 60 INL 7 36 23 42 / 10 0 50 60 BRD 12 37 28 45 / 10 10 70 60 HYR 10 37 24 45 / 60 0 60 70 ASX 16 36 23 43 / 80 0 40 50 && .DLH WATCHES/WARNINGS/ADVISORIES... MN...WINTER STORM WARNING UNTIL MIDNIGHT CDT TONIGHT FOR MNZ012-020- 021. WI...WINTER STORM WARNING UNTIL MIDNIGHT CDT TONIGHT FOR WIZ001>004. LS...GALE WARNING UNTIL 10 PM CDT THIS EVENING FOR LSZ121-140>142- 146>148. SMALL CRAFT ADVISORY UNTIL 10 PM CDT THIS EVENING FOR LSZ143>145. && $$ SHORT TERM...MELDE/DAP AVIATION...MELDE
AREA FORECAST DISCUSSION
NWS TWIN CITIES/CHANHASSEN MN
208 PM CDT FRI APR 19 2013 .UPDATE... UPDATED TO INCLUDE 18Z AVIATION DISCUSSION BELOW && .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 405 AM CDT FRI APR 19 2013 THE POWERFUL WINTER STORM THAT DUMPED OVER A FOOT OF SNOW IN SOME LOCATIONS WILL EXIT THE REGION TODAY. LIGHT DEFORMATION SNOWFALL WILL LINGER OVER THE EASTERN HALF OF THE CWA THIS MORNING...BUT THE LARGE SCALE SUBSIDENCE ASSOCIATED WITH THE APPROACHING UPPER LEVEL RIDGE WILL CLEAR SKIES OUT ACROSS THE WESTERN CWA. WATER VAPOR IMAGERY DEPICTED A SHORTWAVE ON THE DOWNSTREAM AXIS OF THIS AFOREMENTIONED UPPER LEVEL RIDGE...WITH SOME MID LEVEL CLOUDS ACROSS THE WESTERN DAKOTAS. NUMERICAL MODELS HAVE THIS SHORTWAVE WEAKENING WITH TIME...AND THE MID LEVEL CLOUDS DISSIPATING AS THEY DIVE SOUTHWEST OF MINNESOTA. HOWEVER...FARTHER EAST WILL LIKELY SEE SOME DIURNALLY DRIVEN RAIN/SNOW SHOWERS DEVELOP AS THE BOUNDARY LAYER BECOMES DESTABILIZED THIS AFTERNOON WITH A FEW EMBEDDED AREAS OF ENHANCED VORTICITY ROTATING AROUND THE PARENT CYCLONE AIDING IN ASCENT. THIS IS DEPICTED WELL BY ALL 4 MEMBERS OF THE HOPWRF ENSEMBLE. ANOTHER CONCERN IS STRONG SUSTAINED NORTHWEST WINDS...WHICH MAY FLIRT WITH ADVISORY CRITERIA AT TIMES TODAY. BUFR FORECAST SOUNDINGS VIA THE NAM...GFS...AND RAP ALL INDICATE LOW TO MID 30KTS ATOP THE MIXED LAYER...WITH LAYER AVERAGED WINDS IN THE UPPER 20S TO NEAR 30KTS. WE SHOULD BE ABLE TO MIX UP TO 850MB...BUT THE H850 WINDS DECREASE WITH TIME TODAY...SO THEREFORE EXPECTING JUST BLUSTERY...NOT ADVISORY TYPE WINDS. HIGH PRESSURE WILL CONTINUE TO BUILD ACROSS THE REGION TONIGHT WITH CLEARING SKIES AND CALMING WINDS. THIS...COMBINED WITH THE FRESH SNOWPACK...WILL SET THE STAGE FOR RECORD BREAKING LOW TEMPERATURES BY SATURDAY MORNING. .LONG TERM...(SATURDAY THROUGH THURSDAY) ISSUED AT 405 AM CDT FRI APR 19 2013 SATURDAY BRINGS A BRIEF RESPITE IN PRECIPITATION AS SURFACE HIGH PRESSURE ARRIVES. THE COOL WEATHER WILL PERSIST HOWEVER...AS TEMPERATURES BARELY SNEAK ABOVE RECORD LOW VALUES FOR HIGHS. THIS IS ILLUSTRATED BY THE FORECAST HIGH OF 40 AT MSP (WHERE THE RECORD LOW HIGH TEMP FOR THE DATE IS 36) AND A FORECAST HIGH OF 37 AT KSTC (WHERE THE RECORD LOW HIGH TEMP FOR THE DATE IS 35). BY LATE SATURDAY AFTERNOON...A DECENT AREA OF 700-600MB OMEGA AND INCREASING SATURATION IS EXPECTED TO SPREAD FROM WESTERN MN EASTWARD ACROSS THE AREA. THIS SIGNALS THE TRANSITION TO AN ACTIVE ZONAL FLOW REGIME...WITH THE SURFACE REFLECTION (IN THE FORM OF A COLD FRONT) PROGGED TO PASS ACROSS THE REGION LATE SUNDAY INTO MONDAY. WITH THERMAL PROFILES HOVERING AROUND 0C...WILL LIKELY SEE A RAIN-SNOW MIX ON SATURDAY NIGHT AND SUNDAY MORNING...ALTHOUGH ANY SNOW ACCUMULATIONS WOULD BE MINIMAL. BY SUNDAY AFTERNOON...TEMPS WILL BE WARM ENOUGH TO YIELD RAIN. COULD ALSO SEE SOME THUNDER IN CENTRAL/SOUTHERN MN ON SUNDAY AFTERNOON AS THE FRONT AND LOW LEVEL TROUGH PASS...AS SUPPORTED BY SUB-ZERO GFS BEST LI/S ATTENDANT WITH A 50-60 KT 900-850MB JET. ON MONDAY AND TUESDAY...THE ASSOCIATED BAROCLINIC ZONE STALLS JUST SOUTHEAST OF THE AREA...AND FOSTERS A PROLONGED PERIOD OF LIGHT PRECIPITATION CHANCES FROM SOUTHERN MN INTO WEST CENTRAL WI. WINTRY PRECIP WILL CONTINUE TO BE A POSSIBILITY...ESPECIALLY DURING THE NOCTURNAL TIME FRAMES. THURSDAY AND FRIDAY IS EXPECTED TO BRING MODERATING TEMPERATURES AS HEIGHTS BUILD ACROSS THE REGION. BY FRIDAY...COULD SEE HIGHS WELL INTO THE 50S...WITH 60S NOT OUT OF THE QUESTION. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON) ISSUED AT 135 PM CDT FRI APR 19 2013 POTENT WINTER-SEASON STORM EXITING THE AREA WILL ALLOW ALL TERMINALS TO HIT VFR BY LATE THIS EVENING. STILL RECEIVING SOME LIGHT -SHSN AND -SN ECHOES PER KPMX RADAR...MAINLY FROM KMSP EASTWARD. MORE OF A BANDED DISTRIBUTION RATHER THAN SOLID PRECIP SHIELD...SO CONDS AT KMSP-KRNH-KEAU MAY DO SOME BOUNCING AMONG VFR-MVFR-IFR THROUGH 22Z OR SO BEFORE CONDS SOLIDLY REMAIN VFR. SKIES WILL ALSO STEADILY CLEAR OUT TNGT INTO TMRW AS HIGH PRES ARRIVES...ALLOWING FOR SKC TO BE PUT INTO THE TAFS. NW WINDS WILL REMAIN STRONG/GUSTY THRU THIS EVENING THEN STEADILY SETTLE DOWN. WITH THE CENTER OF HIGH PRES MOVING OVERHEAD DURG THE EARLY MRNG HRS...WILL SEE WINDS GO LGT/VRBL TMRW MRNG. KMSP...MAINLY VFR...WITH PRIMARY CONCERN BEING THE FIRST COUPLE OF HOURS OF THE 19/18Z TAF. KMPX RADAR STILL SHOWS BANDED -SHSN AND -SN ECHOES DRIFTING SE ACRS THE AREA...AND REAL-TIME MSP ASOS OBS HAVE FREQUENTLY INDICATED SNOW BEGAN AND ENDED. -SN WILL BE IN THE FORECAST THRU 21Z THEN CONDS STEADILY IMPROVE. VFR CONDS PREVAIL OVERNIGHT THRU TMRW WITH DIMINISHING WINDS...EVENTUALLY BECOMING SLY BY LATE TMRW. CLOUDS INCRS DURG THE DAY TMRW...AND THERE IS A SMALL CHC OF -RA BY 00Z TMRW...TOO LOW TO INCLUDE ATTM. /OUTLOOK FOR KMSP/ SUN...MVFR AND -RA WITH IFR AND TSRA POSSIBLE LATE. WINDS SSW 15-20KT. MON...MVFR WITH IFR AND -RA POSSIBLE. WINDS SW EARLY...BECOMING NW 10-15KT. TUE...MAINLY VFR. MVFR WITH -RASN/-SN POSSIBLE. WINDS NW 10-15 KT. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...NONE. WI...NONE. && $$ UPDATE...JPC SHORT TERM...JRB LONG TERM...LS AVIATION...JPC
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 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
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
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
149 PM EDT FRI APR 19 2013 .SYNOPSIS... A COLD FRONT WILL MOVE EAST FROM THE GREAT LAKES TODAY AND WILL MOVE ACROSS THE NORTH COUNTRY TONIGHT...BRINGING GUSTY SOUTHERLY WINDS AND RAIN SHOWERS AND POSSIBLE THUNDERSTORMS LATE THIS AFTERNOON AND TONIGHT. MUCH COOLER WEATHER WILL BE OVER THE REGION ON SATURDAY. A RIDGE OF HIGH PRESSURE WILL BUILD INTO THE REGION SATURDAY NIGHT AND WILL REMAIN OVER THE NORTH COUNTRY THROUGH MONDAY. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... AS OF 1221 PM EDT FRIDAY...MINOR UPDATES TO T/TD/MAX T NUMBERS THROUGH EARLY EVENING BASED OFF CURRENT OBSERVATIONAL DATA AND LATEST LAMP/RAP DATA. OTHERWISE NO OTHER APPRECIABLE ADJUSTMENTS NEEDED ATTM. PRIOR DISCUSSION FOLLOWS... A VERY WINDY AND MILD DAY STILL ON TAP WITH MODEST UPDATES TO TEMPS/WIND/WIND GUSTS AND POPS THROUGH THE EVENING HOURS TO ACCT FOR CURRENT AND EXPECTED TRENDS. BASED OFF MOST RECENT RAP/NAM12 MIXED LAYER SOUNDINGS AND CURRENT OBSERVATIONAL DATA HAVE GONE AHEAD AND ISSUED A WIND ADVISORY FROM THE CHAMPLAIN VALLEY WEST INTO OUR NRN NY COUNTIES THROUGH THIS EVENING FOR SOUTH/SOUTHWESTERLY GUSTS INTO THE 45 TO 55 MPH RANGE. ALREADY HAVE RECEIVED ISOLATED TREE/POWER OUTAGE REPORTS EITHER FROM LAST NIGHT OR THIS MORNING...AND EXPECTED MORE OF THE SAME TODAY/THIS EVENING AS PRE- FRONTAL P-GRAD REMAINS TIGHT AND PBL DEEPENS (SEE OUR LATEST REPORTS). STILL EXPECTING THE FRONTAL BOUNDARY TO ARRIVE INTO OUR FAR WESTERN COUNTIES BY LATE THIS AFTERNOON...AND INTO VT TOWARD SUNSET. STRONG ANAFRONTAL SIGNATURE WITH THIS FEATURE WITH PRIMARY RAIN SHIELD BEHIND THE WIND SHIFT. INDEED...AN INCREDIBLY TIGHT 925 MB THERMAL GRADIENT ALONG THE FRONT WITH VALUES DROPPING FROM +18C TO +5C IN A MATTER OF 50 NM OR SO. THIS TYPE OF FORCING MAY LEAD TO SHALLOW CONVECTIVE FINE- LINE DEVELOPMENT ACROSS OUR NRN NY/CHAMPLAIN VALLEY COUNTIES RIGHT ALONG THE SFC BOUNDARY BEFORE WEAKENING AS IT PROGRESSES INTO ERN VT AS SUGGESTED BY THE HRRR DATA. WITH SUCH WIND IN THE PBL...UPDRAFT STRENGTH AND LIGHTNING THREAT LIKELY MINIMAL...BUT AN ENHANCED CONVECTIVE WIND THREAT MAY AT LEAST BE PLAUSIBLE SHOULD SUCH A FEATURE DEVELOP. TIME WILL TELL. OVERALL RAIN AMOUNTS GENERALLY IN THE 0.33 TO 0.75 INCH RANGE WITH CUSTOMARY VARIATION...ESPECIALLY GIVEN STRONG FLOW AND LOCALIZED OROGRAPHICAL EFFECTS. && .SHORT TERM /6 PM THIS EVENING THROUGH SUNDAY/... AS OF 458 AM EDT FRIDAY...THE COLD FRONT WILL MOVE THROUGH THE REGION TONIGHT. HAVE GONE WITH LIKELY TO CATEGORICAL POPS FOR RAIN SHOWERS TONIGHT. MUCH COOLER TEMPERATURES WILL BE OVER THE REGION ON SATURDAY WITH HIGHS FROM THE UPPER 40S TO LOWER 50S. THERE WILL BE A SLIGHT CHANCE FOR SOME RAIN SHOWERS OVER THE HIGHER ELEVATIONS OF THE ADIRONDACKS AND GREEN MOUNTAINS ON SATURDAY. A RIDGE OF HIGH PRESSURE WILL BUILD INTO THE REGION SATURDAY NIGHT AND SUNDAY...WITH LOWS SATURDAY NIGHT IN THE TEENS AND 20S. && .LONG TERM /SUNDAY NIGHT THROUGH THURSDAY/... AS OF 512 AM EDT FRIDAY...SFC RIDGE NEARBY ON SUNDAY NIGHT INTO MONDAY AND ASSOCIATED DEEP DRY LAYER WL RESULT IN MAINLY CLR SKIES. PROGGED 85H TEMPS BTWN -2C AND -4C SUPPORT HIGHS IN THE M40S NEK/MTNS TO M50S CPV/SLV. STILL PLENTY OF UNCERTAINTY FOR TUESDAY AND BEYOND WITH REGARDS TO POTENTIAL COASTAL SYSTEM ON TUESDAY AND ANOTHER GREAT LAKES CUTTER ON THURS. LATEST 00Z ECMWF SHOWS SFC LOW PRES DEVELOPING ACRS SNE ON TUES...AS 5H S/W ENERGY TRACKS ACRS OUR FA. ECWMF SHOWS BEST 850 TO 500MB RH JUST TOO OUR EAST...ALONG WITH NO CLOSED 5H/7H CIRCULATION...THEREFORE FEEL IMPACT TO OUR CWA WL BE LIMITED. WL CONT TO MENTION LOW CHC POPS. TEMPS WL BE COOL WITH PROGGED 85H TEMPS NEAR 0C...AND LIMITED MIXING FROM CLOUDS...THINKING MAINLY 40S EASTERN/CENTRAL VT/MTNS AND L/M 50S ELSEWHERE. BOTH GFS/ECMWF CONTS TO SUPPORT AN ACTIVE PATTERN WITH ANOTHER SYSTEM IMPACTING OUR FA LATE WEDS INTO THURS. STILL SOME UNCERTAINTY WITH REGARDS TO TIMING OF MOISTURE/QPF AND EXACT STORM TRACK. LATEST TRENDS SHOW SFC LOW PRES TRACKING TO OUR WEST...WITH GUSTY SOUTHERLY WINDS DEVELOPING ON WEDS AFTN INTO THURS...VERY SIMILAR TO THE SYSTEM TODAY. GIVEN EXPECTED TRACK TO OUR WEST...ANTICIPATE OUR CWA WL BE IN THE WARM SECTOR WITH MUCH ABOVE NORMAL TEMPS POSSIBLE WEDS INTO THURSDAY...ALONG WITH A BRIEF 3 TO 6 HR WINDOW OF SHOWERS. WL TREND TWD ABOVE NORMAL TEMPS AND MENTION CHC POPS ATTM. AS THE EVENT BECMG CLOSER...WL FINE TUNE TEMPS/POP TIMING...ALONG WITH QPF AMOUNTS. && .AVIATION /18Z FRIDAY THROUGH WEDNESDAY/... THROUGH 00Z SUNDAY...STRONG COLD FRONT PASSES FROM WEST-EAST THROUGH THE NORTH COUNTRY BETWEEN 21-03Z...BRINGING BRIEFLY HEAVY RAIN SHOWERS (20-30 MINUTES OF IFR CONDITIONS) AND POSSIBLE WIND GUSTS TO 45 KTS AS WINDS SHIFT FROM THE SOUTH INTO THE WEST. IN ADVANCE OF THE FRONT THRU 21Z...STRONG PRESSURE GRADIENT IN PLACE WILL MAINTAIN SOUTH WINDS 15-25 KTS WITH GUSTS TO 35 KTS...FOLLOWED BY SHARP WLY WIND SHIFT WITH FRONTAL PASSAGE AND BRIEF GUSTS TO 35 KTS FROM THE WEST UNTIL AROUND 03Z. LINGERING SHOWER ACTIVITY CLEARS TO THE EAST BY 06Z. VFR SATURDAY WITH SCT040-050. WITH DAYTIME HEATING...IT APPEARS SW-W WINDS WILL BECOME GUSTY AGAIN WITH GUSTS 25-30 KTS AFTER 14Z SATURDAY. OUTLOOK 00Z SUNDAY THROUGH WEDNESDAY...STRONG SFC HIGH PRESSURE CENTERED ACROSS THE GREAT LAKES REGION SATURDAY NIGHT WILL BUILD EWD ACROSS THE NORTH COUNTRY ON SUNDAY BRINGING VFR CONDITIONS AND GENERALLY LIGHT WINDS. THIS RIDGE WILL BE THE CONTROLLING WX FEATURE FOR SEVERAL DAYS. DRY CONDITIONS SHOULD PERSIST UNTIL ARRIVAL OF NEXT FRONTAL SYSTEM LATE WEDNESDAY WITH POSSIBLE -SHRA AND MVFR CONDITIONS. && .BTV WATCHES/WARNINGS/ADVISORIES... VT...WIND ADVISORY UNTIL 11 PM EDT THIS EVENING FOR VTZ001-002-005- 009-011. NY...WIND ADVISORY UNTIL 11 PM EDT THIS EVENING FOR NYZ026>031-034- 035-087. && $$ SYNOPSIS...WGH NEAR TERM...JMG SHORT TERM...WGH LONG TERM...TABER AVIATION...BANACOS
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 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
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 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 WILMINGTON NC
744 PM EDT FRI APR 19 2013 .SYNOPSIS... UNSETTLED WEATHER CAN BE EXPECTED THE REMAINDER OF TODAY AND OVERNIGHT AS A VIGOROUS STORM SYSTEM PUSHES A STRONG COLD FRONT ACROSS THE AREA. SHOWERS AND THUNDERSTORMS...SOME POSSIBLY SEVERE CAN BE EXPECTED. COOLER AIR WILL OVERSPREAD THE REGION THIS WEEKEND. LOW PRESSURE TRACKING TO THE NORTH AND OFFSHORE OF THE CAROLINAS MONDAY INTO TUESDAY WILL BRING BREEZY CONDITIONS AND PERIODS OF RAIN NEAR THE COAST. && .NEAR TERM /THROUGH SATURDAY/... AS OF 725 PM FRIDAY...NO MAJOR CHANGES AT THIS TIME, JUST KEEPING TIMING OF SQUALL LINE UP TO DATE IN NEAR TERM GRIDS. AS SUCH HAVE CANCELLED TORNADO WATCH FOR DARLINGTON MARLBORO AND WILL PROB DO SO AT 8-ISH FOR THE NEXT ROW OF COUNTIES. SEVERE WEATHER THREAT FURTHER EAST ALSO APPEARS TO BE WANING AS SPC RUC ANALYSIS SHOWS ALL SFC BASED CAPE CAPPED. 1000J PER KG OF ML CAPE REMAIN UPSTREAM OF STORMS FOR ABOUT THE NEXT HOUR BUT ALSO CAPPED ALONG NC COASTAL ZONES. BUFR SOUNDINGS SHOW STORM BASES ANYWHERE FROM 3-5KFT THAT FAR EAST...AS THE WHOLE LINE WILL DECELERATE AND HAVE LESS INSTABILITY TO WORK WITH IN THE LOW LEVELS. VERTICAL VELOCITIES PROGGED TO REMAIN QUITE DEEP THOUGH SO WILL LEAVE SEVERE WORDING AND WATCH AS-IS SINCE ISO STRONG TO DMG WIND STILL NOT IMPOSSIBLE ESP WITH A LITTLE DRY AIR ALOFT SHOWING UP IN THE SAME SOUNDINGS. FROM PREVIOUS: BEHIND THE SQUALL LINE...WHICH WILL CROSS BETWEEN APPROX 7PM AND 3AM...A LARGE AREA OF MDT STRATIFORM RAIN WILL EXIST. WHILE SEVERE THREAT WILL END BEHIND THE SQUALL LINE...THIS CONTINUED RAIN WILL STILL ADD A DECENT SLUG OF QPF...AND EVENT-TOTAL RAINFALL WILL BE AROUND AN INCH IN MANY SPOTS...WITH SCATTERED HIGHER RAINFALL AMOUNTS. ACTUAL FROPA WILL OCCUR FROM WEST TO EAST A FEW HOURS BEHIND THE SQUALL LINE...AROUND MIDNIGHT IN THE WEST TO 5AM OFFSHORE. TEMPS SHOULD FALL PRETTY QUICKLY BEHIND THE BOUNDARY...BUT HAVE ONCE AGAIN LEANED ON THE WARMER MET GUIDANCE WHICH HAS BEEN PERFORMING BETTER AS OF LATE. EXPECT LOWS 52-54 FAR WEST...58-61 NEAR THE COAST. && .SHORT TERM /SATURDAY NIGHT THROUGH SUNDAY NIGHT/... AS OF 3 PM FRIDAY...NOTABLE LAGGING OF THE UPPER TROUGH RELATIVE TO THE POSITION OF THE SURFACE FRONT...AND AN ENTRANCE REGION OF THE ASSOCIATED JET OVERHEAD BY DAYBREAK SATURDAY...WILL PROMOTE POST FRONTAL STRATIFORM RAIN ALONG THE COAST AT 12Z/8AM EVEN THOUGH THE COLD FRONT ITSELF WILL BE LOCATED WELL OFFSHORE. FORECAST SOUNDINGS SHOW DRY AIR ALOFT INFILTRATING AND SHUTTING DOWN PCPN INTO MIDDAY TO EARLY AFTERNOON WITH PARTIAL CLEARING ACROSS THE FORECAST AREA THROUGH SATURDAY AFTERNOON. MAXIMUM TEMPERATURES SATURDAY BETWEEN 15-20 DEGREES COOLER THAN TODAY EQUATING TO AROUND 10 DEGREES BELOW NORMAL FOR APRIL 20TH. INVERTED SURFACE TROUGH AMPLIFYING FROM THE BAHAMAS NORTHWARD WILL BRING A PINCHED GRADIENT AND STIFF NE WINDS SUNDAY. RAIN ASSOCIATED WITH THE CONVERGENCE OF THIS FEATURE WILL FAVOR A BEST CHANCE OF RAIN NEAR THE COAST INTO THE COASTAL INTERIOR. CLOUDS AND BLUSTERY NE WINDS SUNDAY WILL KEEP TEMPERATURES BELOW NORMAL AND QUITE SIMILAR TO SATURDAY READINGS. && .LONG TERM /MONDAY THROUGH FRIDAY/... AS OF 3 PM FRIDAY...MID LEVEL PATTERN WILL FEATURE BASICALLY A ZONAL FLOW INITIALLY WITH A FAIRLY DEEP AND PROGRESSIVE EAST COAST TROUGH MOVING ACROSS LATE IN THE PERIOD. AT THE SURFACE LOW PRESSURE WILL MOVE UP JUST OFFSHORE MONDAY AND MAINTAINED THE CHANCE POPS WITH HIGHEST VALUES ALONG THE IMMEDIATE COAST. TUESDAY AND WEDNESDAY FOR THE MOST PART SHOULD BE DRY ALTHOUGH THE MAIN SHORTWAVE WITH THE AFOREMENTIONED TROUGH WILL BE KNOCKING ON THE DOORSTEP AND SLIGHT CHANCE POPS ARE INCLUDED IN THE FORECAST. THE FRONT SHOULD MOVE ACROSS THE AREA LATE WEDNESDAY INTO THURSDAY MORNING. HPC POPS INCLUDE EASTERN THIRD FOR THURSDAY TO ADDRESS THE INHERENT TIMING UNCERTAINTIES. TEMPERATURE TRENDS REMAIN INTACT WITH A NOD TO SLIGHTLY BELOW CLIMATOLOGY THROUGH MOST OF THE PERIOD. && .AVIATION /00Z SATURDAY THROUGH WEDNESDAY/... AS OF 00Z...MVFR/IFR AT THE INLAND SITES THIS EVENING WILL SOON SPREAD TO COASTAL SITES OVER THE NEXT FEW HOURS...AND CONTINUE THROUGH MUCH OF THE OVERNIGHT PERIOD. CONDITIONS WILL SLOWLY IMPROVE FROM MVFR TO VFR THROUGHOUT THE MORNING HOURS...WITH VFR PREVAILING SATURDAY AFTERNOON AND EVENING. A LINE OF SHOWERS AND THUNDERSTORMS CONTINUE TO PROGRESS EASTWARD ACROSS THE AREA...CREATING MVFR AND PERIODS OF IFR AT THE INLAND SITES DUE TO HEAVY RAINFALL. AS ACTIVITY MOVES EASTWARD...EXPECT MVFR/IFR CONDITIONS TO SOON SPREAD TO THE COASTAL SITES AS WELL. CONFIDENCE IS LOWERED AS TO WHETHER OR NOT STRONG STORMS WILL STAY INTACT ONCE THEY REACH THE COASTAL SITES...BUT GIVEN PRIOR HISTORY OF LINE...HAVE OPTED TO KEEP IN TSRA ACTIVITY FOR THE COASTALS OVER THE NEXT FEW HOURS. GUSTY SOUTH-SOUTHWEST WINDS ARE POSSIBLE WITH ANY STRONG STORMS...AS WELL AS AHEAD OF THE APPROACHING LINE. BEHIND THE CONVECTION...ANTICIPATE SHOWERS TO CONTINUE THROUGH MUCH OF THE OVERNIGHT HOURS AND POSSIBLY INTO THE EARLY MORNING HOURS...WITH AREAS OF FOG LIKELY AS WELL. MAY SEE LOWERED CIGS ALONG THE COAST. AFTER DAYBREAK...MVFR WILL GRADUALLY LIFT TO VFR...WITH WINDS VEERING AND BECOMING GENERALLY NORTH-NORTHWEST FOR THE REMAINDER OF THE DAY. SUSTAINED WINDS WILL BE AOB 12 KTS...AND SKIES WILL BEGIN TO CLEAR TOWARDS THE END OF THE PERIOD. EXTENDED OUTLOOK...IMPROVING CONDITIONS BEHIND THE FRONT SATURDAY MORNING. THE COLD FRONT WEAKENS BUT STALLS NEAR THE COAST...WITH UNSETTLED WEATHER POSSIBLE FOR THE COASTAL TERMINALS MONDAY INTO TUESDAY MORNING. SHOWERS LATE WEDNESDAY WITH ANOTHER FRONT. && .MARINE... NEAR TERM /THROUGH TONIGHT/... AS OF 730 PM FRIDAY...NO CHANGES AT ALL. WATERS REMAIN IN VIGOROUS PREFRONTAL FLOW REGIME AND THE SLOWING NATURE OF THE BOUNDARY WILL KEEP THESE WINDS IN PLACE NEXT SEVERAL HOURS UNTIL WIND SHIFT WITH FROPA. PREV DISCUSSION FOLLOWS. AS OF 3 PM FRIDAY...SCA REMAINS IN EFFECT FOR THE ENTIRE AREA AND SEAS AT THE LOCAL BUOYS RANGE FROM 7 FT AT FRYING PAN SHOALS...TO 4-5 FT CLOSE TO THE COAST. THESE SEAS WILL CONTINUE TO BUILD AS SOUTHERLY WINDS RISE DUE TO AN INCREASING PRESSURE GRADIENT BETWEEN OFFSHORE HIGH PRESSURE AND A COLD FRONT SLOWLY APPROACHING FROM THE WEST. WINDS WILL INCREASE TO 15-25 KTS...WITH GUSTS AROUND 30 KTS...HIGHEST LATE THIS EVE AND TONIGHT. ISOLATED GUSTS TO GALE FORCE ARE POSSIBLE AS WELL...BUT STILL WILL HOLD ON TO SCA AS OPPOSED TO A GALE WARNING SINCE STILL-COLD SSTS WILL LIMIT SOMEWHAT THE GUST POTENTIAL. FROPA WILL OCCUR AT THE END OF THE PERIOD...WITH A SUDDEN WIND SHIFT TO THE NW BY SATURDAY MORNING...BUT STILL AT 15-20 KTS. MAXIMUM WAVE HEIGHTS WILL REACH 6-9 FT TONIGHT...FALLING SLOWLY AT THE END OF THE PERIOD DUE TO THE DEVELOPING OFFSHORE WINDS. ADDITIONALLY...STRONG CONVECTION IS POSSIBLE AHEAD OF THE COLD FRONT LATE TONIGHT. ISOLATED MUCH STRONGER WIND GUSTS ARE POSSIBLE WITHIN THIS CONVECTION WHICH WILL MOST LIKELY MOVE ACROSS THE WATERS BETWEEN 4AM AND 7AM SATURDAY MORNING. VERY HEAVY RAINFALL AND CLOUD TO SEA LIGHTNING WILL ACCOMPANY THE THUNDERSTORMS AS WELL. SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/... AS OF 3 PM FRIDAY...NOT A BANNER WEEKEND FOR MARINE ACTIVITIES AS THE OCEAN WILL BE HAZARDOUS BOTH SATURDAY AND SUNDAY...WITH JUST A VERY BRIEF LULL IN WINDS DURING THE DAY SATURDAY AS SEAS RECOVER ONLY TEMPORARILY. THE SEA IS ALREADY AGITATED...AND SATURDAY EVEN THOUGH WINDS BEHIND THE FRONT EASE BELOW ADVISORY LEVELS...THE SEAS WILL NOT FULLY RECOVER IN TIME BEFORE NE WINDS INCREASE LATE SATURDAY NIGHT AND RE-BUILD THE WAVES. LOW PRESSURE AMPLIFYING FROM THE BAHAMAS OFFSHORE OF OUR COAST WILL BRING 7-11 FT SEAS BY LATE SUNDAY. LARGE S WAVES INTO EARLY SATURDAY WILL SUBSIDE A BIT ONLY TO BECOME GROWING E WAVES SUNDAY. FOR THIS REASON THE ADVISORY HAS BEEN EXTENDED THROUGH THE WEEKEND AND THE DAY MONDAY. STRONG TSTMS MAY BE IMPACTING THE OUTER WATERS AND THE GULF STREAM DAYBREAK SATURDAY. LONG TERM /MONDAY THROUGH TUESDAY/... AS OF 3 PM FRIDAY...FAIRLY STRONG WINDS INITIALLY AS LOW PRESSURE MOVING NORTHEAST...WITH THE CENTER PROBABLY JUST OUTSIDE THE COASTAL WATERS COMBINES WITH HIGH PRESSURE TO THE NORTHEAST TO CREATE A CONSIDERABLE GRADIENT. SHOULD SEE NE WINDS OF 20-25 KNOTS DROPPING TO 15-20 EARLY TUESDAY. FINALLY...BY WEDNESDAY WE SHOULD SEE WINDS DIMINISH CONSIDERABLY AND A RETURN FLOW SHOULD DEVELOP. REGARDING SEAS...MAY SEE SOME SEVEN FOOTERS INITIALLY WITH 5-7 FEET ACROSS OUTER WATERS DROPPING CONSIDERABLY WITH THE WINDS TUESDAY AND WEDNESDAY. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...NONE. NC...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 6 PM EDT MONDAY FOR AMZ250-252-254- 256. && $$ NEAR TERM...JDW/MBB SHORT TERM...MJC LONG TERM...SHK AVIATION...SGL
AREA FORECAST DISCUSSION
NWS WILMINGTON NC
725 PM EDT FRI APR 19 2013 .SYNOPSIS... UNSETTLED WEATHER CAN BE EXPECTED THE REMAINDER OF TODAY AND OVERNIGHT AS A VIGOROUS STORM SYSTEM PUSHES A STRONG COLD FRONT ACROSS THE AREA. SHOWERS AND THUNDERSTORMS...SOME POSSIBLY SEVERE CAN BE EXPECTED. COOLER AIR WILL OVERSPREAD THE REGION THIS WEEKEND. LOW PRESSURE TRACKING TO THE NORTH AND OFFSHORE OF THE CAROLINAS MONDAY INTO TUESDAY WILL BRING BREEZY CONDITIONS AND PERIODS OF RAIN NEAR THE COAST. && .NEAR TERM /THROUGH TONIGHT/... AS OF 725 PM FRIDAY...NO MAJOR CHANGES AT THIS TIME, JUST KEEPING TIMING OF SQUALL LINE UP TO DATE IN NEAR TERM GRIDS. AS SUCH HAVE CANCELLED TORNADO WATCH FOR DARLINGTON MARLBORO AND WILL PROB DO SO AT 8-ISH FOR THE NEXT ROW OF COUNTIES. SEVERE WEATHER THREAT FURTHER EAST ALSO APPEARS TO BE WANING AS SPC RUC ANALYSIS SHOWS ALL SFC BASED CAPE CAPPED. 1000J PER KG OF ML CAPE REMAIN UPSTREAM OF STORMS FOR ABOUT THE NEXT HOUR BUT ALSO CAPPED ALONG NC COASTAL ZONES. BUFR SOUNDINGS SHOW STORM BASES ANYWHERE FROM 3-5KFT THAT FAR EAST...AS THE WHOLE LINE WILL DECELERATE AND HAVE LESS INSTABILITY TO WORK WITH IN THE LOW LEVELS. VERTICAL VELOCITIES PROGGED TO REMAIN QUITE DEEP THOUGH SO WILL LEAVE SEVERE WORDING AND WATCH AS-IS SINCE ISO STRONG TO DMG WIND STILL NOT IMPOSSIBLE ESP WITH A LITTLE DRY AIR ALOFT SHOWING UP IN THE SAME SOUNDINGS. FROM PREVIOUS: BEHIND THE SQUALL LINE...WHICH WILL CROSS BETWEEN APPROX 7PM AND 3AM...A LARGE AREA OF MDT STRATIFORM RAIN WILL EXIST. WHILE SEVERE THREAT WILL END BEHIND THE SQUALL LINE...THIS CONTINUED RAIN WILL STILL ADD A DECENT SLUG OF QPF...AND EVENT-TOTAL RAINFALL WILL BE AROUND AN INCH IN MANY SPOTS...WITH SCATTERED HIGHER RAINFALL AMOUNTS. ACTUAL FROPA WILL OCCUR FROM WEST TO EAST A FEW HOURS BEHIND THE SQUALL LINE...AROUND MIDNIGHT IN THE WEST TO 5AM OFFSHORE. TEMPS SHOULD FALL PRETTY QUICKLY BEHIND THE BOUNDARY...BUT HAVE ONCE AGAIN LEANED ON THE WARMER MET GUIDANCE WHICH HAS BEEN PERFORMING BETTER AS OF LATE. EXPECT LOWS 52-54 FAR WEST...58-61 NEAR THE COAST. && .SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/... AS OF 3 PM FRIDAY...NOTABLE LAGGING OF THE UPPER TROUGH RELATIVE TO THE POSITION OF THE SURFACE FRONT...AND AN ENTRANCE REGION OF THE ASSOCIATED JET OVERHEAD BY DAYBREAK SATURDAY...WILL PROMOTE POST FRONTAL STRATIFORM RAIN ALONG THE COAST AT 12Z/8AM EVEN THOUGH THE COLD FRONT ITSELF WILL BE LOCATED WELL OFFSHORE. FORECAST SOUNDINGS SHOW DRY AIR ALOFT INFILTRATING AND SHUTTING DOWN PCPN INTO MIDDAY TO EARLY AFTERNOON WITH PARTIAL CLEARING ACROSS THE FORECAST AREA THROUGH SATURDAY AFTERNOON. MAXIMUM TEMPERATURES SATURDAY BETWEEN 15-20 DEGREES COOLER THAN TODAY EQUATING TO AROUND 10 DEGREES BELOW NORMAL FOR APRIL 20TH. INVERTED SURFACE TROUGH AMPLIFYING FROM THE BAHAMAS NORTHWARD WILL BRING A PINCHED GRADIENT AND STIFF NE WINDS SUNDAY. RAIN ASSOCIATED WITH THE CONVERGENCE OF THIS FEATURE WILL FAVOR A BEST CHANCE OF RAIN NEAR THE COAST INTO THE COASTAL INTERIOR. CLOUDS AND BLUSTERY NE WINDS SUNDAY WILL KEEP TEMPERATURES BELOW NORMAL AND QUITE SIMILAR TO SATURDAY READINGS. && .LONG TERM /MONDAY THROUGH FRIDAY/... AS OF 3 PM FRIDAY...MID LEVEL PATTERN WILL FEATURE BASICALLY A ZONAL FLOW INITIALLY WITH A FAIRLY DEEP AND PROGRESSIVE EAST COAST TROUGH MOVING ACROSS LATE IN THE PERIOD. AT THE SURFACE LOW PRESSURE WILL MOVE UP JUST OFFSHORE MONDAY AND MAINTAINED THE CHANCE POPS WITH HIGHEST VALUES ALONG THE IMMEDIATE COAST. TUESDAY AND WEDNESDAY FOR THE MOST PART SHOULD BE DRY ALTHOUGH THE MAIN SHORTWAVE WITH THE AFOREMENTIONED TROUGH WILL BE KNOCKING ON THE DOORSTEP AND SLIGHT CHANCE POPS ARE INCLUDED IN THE FORECAST. THE FRONT SHOULD MOVE ACROSS THE AREA LATE WEDNESDAY INTO THURSDAY MORNING. HPC POPS INCLUDE EASTERN THIRD FOR THURSDAY TO ADDRESS THE INHERENT TIMING UNCERTAINTIES. TEMPERATURE TRENDS REMAIN INTACT WITH A NOD TO SLIGHTLY BELOW CLIMATOLOGY THROUGH MOST OF THE PERIOD. && .AVIATION /19Z FRIDAY THROUGH WEDNESDAY/... AS OF 18Z...CURRENT FORECAST LOOKS ON TRACK...HOWEVER THE ONSET OF THE HEAVIER CONVECTION WAS BUMPED FORWARD AN HOUR FOR THE WESTERN TERMINALS. SCATTERED LOW TOPPED CONVECTION IS EXPECTED THIS AFTERNOON...MAINLY NEAR THE COAST. COVERAGE WILL BE LIMITED AT FIRST...BUT DEEP MOISTURE MOVES IN THIS EVENING. MODERATE FRONTAL LIFT...COMBINED WITH LOW LEVEL JET...MODERATE BULK SHEAR AND INSTABILITY WILL KICK OFF A 3-4 HOUR WINDOW OF THUNDERSTORMS...SOME STRONG. WINDS WILL GUST IN CONVECTION TO 35 KTS OR MORE. AFTER THE STRONG CONVECTION...EXPECT MORE OF A STRATIFORM RAIN WITH IFR CONDITIONS. THE FRONT CLEARS THE INLAND TERMINALS BY 08Z...WITH A WIND SHIFT TO THE NORTHWEST AND SLOWLY IMPROVING CONDITIONS. SATURDAY...SOME LINGERING PRECIP ALONG THE COAST...WITH IFR CEILINGS IMPROVING TO VFR BY MID TO LATE MORNING. WINDS WILL VEER TO THE NORTHEAST BY 15Z WITH HIGH PRESSURE BEGINNING TO BUILD IN. EXTENDED OUTLOOK...IMPROVING CONDITIONS BEHIND THE FRONT SATURDAY MORNING. THE COLD FRONT WEAKENS BUT STALLS NEAR THE COAST...WITH UNSETTLED WEATHER POSSIBLE FOR THE COASTAL TERMINALS MONDAY INTO TUESDAY MORNING. SHOWERS LATE WEDNESDAY WITH ANOTHER FRONT. && .MARINE... NEAR TERM /THROUGH TONIGHT/... AS OF 730 PM FRIDAY...NO CHANGES AT ALL. WATERS REMAIN IN VIGOROUS PREFRONTAL FLOW REGIME AND THE SLOWING NATURE OF THE BOUNDARY WILL KEEP THESE WINDS IN PLACE NEXT SEVERAL HOURS UNTIL WIND SHIFT WITH FROPA. PREV DISCUSSION FOLLOWS. AS OF 3 PM FRIDAY...SCA REMAINS IN EFFECT FOR THE ENTIRE AREA AND SEAS AT THE LOCAL BUOYS RANGE FROM 7 FT AT FRYING PAN SHOALS...TO 4-5 FT CLOSE TO THE COAST. THESE SEAS WILL CONTINUE TO BUILD AS SOUTHERLY WINDS RISE DUE TO AN INCREASING PRESSURE GRADIENT BETWEEN OFFSHORE HIGH PRESSURE AND A COLD FRONT SLOWLY APPROACHING FROM THE WEST. WINDS WILL INCREASE TO 15-25 KTS...WITH GUSTS AROUND 30 KTS...HIGHEST LATE THIS EVE AND TONIGHT. ISOLATED GUSTS TO GALE FORCE ARE POSSIBLE AS WELL...BUT STILL WILL HOLD ON TO SCA AS OPPOSED TO A GALE WARNING SINCE STILL-COLD SSTS WILL LIMIT SOMEWHAT THE GUST POTENTIAL. FROPA WILL OCCUR AT THE END OF THE PERIOD...WITH A SUDDEN WIND SHIFT TO THE NW BY SATURDAY MORNING...BUT STILL AT 15-20 KTS. MAXIMUM WAVE HEIGHTS WILL REACH 6-9 FT TONIGHT...FALLING SLOWLY AT THE END OF THE PERIOD DUE TO THE DEVELOPING OFFSHORE WINDS. ADDITIONALLY...STRONG CONVECTION IS POSSIBLE AHEAD OF THE COLD FRONT LATE TONIGHT. ISOLATED MUCH STRONGER WIND GUSTS ARE POSSIBLE WITHIN THIS CONVECTION WHICH WILL MOST LIKELY MOVE ACROSS THE WATERS BETWEEN 4AM AND 7AM SATURDAY MORNING. VERY HEAVY RAINFALL AND CLOUD TO SEA LIGHTNING WILL ACCOMPANY THE THUNDERSTORMS AS WELL. SHORT TERM /SATURDAY THROUGH SUNDAY NIGHT/... AS OF 3 PM FRIDAY...NOT A BANNER WEEKEND FOR MARINE ACTIVITIES AS THE OCEAN WILL BE HAZARDOUS BOTH SATURDAY AND SUNDAY...WITH JUST A VERY BRIEF LULL IN WINDS DURING THE DAY SATURDAY AS SEAS RECOVER ONLY TEMPORARILY. THE SEA IS ALREADY AGITATED...AND SATURDAY EVEN THOUGH WINDS BEHIND THE FRONT EASE BELOW ADVISORY LEVELS...THE SEAS WILL NOT FULLY RECOVER IN TIME BEFORE NE WINDS INCREASE LATE SATURDAY NIGHT AND RE-BUILD THE WAVES. LOW PRESSURE AMPLIFYING FROM THE BAHAMAS OFFSHORE OF OUR COAST WILL BRING 7-11 FT SEAS BY LATE SUNDAY. LARGE S WAVES INTO EARLY SATURDAY WILL SUBSIDE A BIT ONLY TO BECOME GROWING E WAVES SUNDAY. FOR THIS REASON THE ADVISORY HAS BEEN EXTENDED THROUGH THE WEEKEND AND THE DAY MONDAY. STRONG TSTMS MAY BE IMPACTING THE OUTER WATERS AND THE GULF STREAM DAYBREAK SATURDAY. LONG TERM /MONDAY THROUGH TUESDAY/... AS OF 3 PM FRIDAY...FAIRLY STRONG WINDS INITIALLY AS LOW PRESSURE MOVING NORTHEAST...WITH THE CENTER PROBABLY JUST OUTSIDE THE COASTAL WATERS COMBINES WITH HIGH PRESSURE TO THE NORTHEAST TO CREATE A CONSIDERABLE GRADIENT. SHOULD SEE NE WINDS OF 20-25 KNOTS DROPPING TO 15-20 EARLY TUESDAY. FINALLY...BY WEDNESDAY WE SHOULD SEE WINDS DIMINISH CONSIDERABLY AND A RETURN FLOW SHOULD DEVELOP. REGARDING SEAS...MAY SEE SOME SEVEN FOOTERS INITIALLY WITH 5-7 FEET ACROSS OUTER WATERS DROPPING CONSIDERABLY WITH THE WINDS TUESDAY AND WEDNESDAY. && .ILM WATCHES/WARNINGS/ADVISORIES... SC...NONE. NC...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 8 PM EDT SATURDAY FOR AMZ250-252- 254-256. && $$ NEAR TERM...MBB/JDW SHORT TERM...MJC LONG TERM...SHK AVIATION...DL/JDW
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 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
1250 PM CDT FRI APR 19 2013 .UPDATE... ISSUED AT 1251 PM CDT FRI APR 19 2013 FOR THE EARLY AFTERN0ON UPDATE...BUMPED UP TEMPERATURES MANY AREAS A COUPLE OF DEGREES. MANY AREAS ARE CURRENTLY 1-3 DEGREES FROM FORECAST HIGH TEMPERATURES. SNOWPACK WILL SLOW THE AFTERNOON DIURNAL RISE...SO A COUPLE OF DEGREES SHOULD SUFFICE. OTHERWISE NO CHANGES TO THE CURRENT FORECAST. UPDATE ISSUED AT 1005 AM CDT FRI APR 19 2013 MAIN FORECAST CONCERN FOR THE UPDATE THIS MORNING IS SKY COVER OR LACK THEREOF...AND PRECIPITATION CHANCES. HIGH PRESSURE FROM MANITOBA AND SASKATCHEWAN EXTENDS SOUTH INTO NORTH DAKOTA. THIS HAS RESULTED IN MAINLY CLEAR SKIES WESTERN AND CENTRAL NORTH DAKOTA...EXCEPT FOR THE FAR SOUTHWEST CORNER. A SHORTWAVE THAT DROPPED THROUGH WESTERN NORTH DAKOTA DID PRODUCE SOME LIGHT SNOW OVER THE SOUTHWEST. THERE ARE SOME LINGERING LIGHT SNOW SHOWERS FROM BEACH TO BOWMAN...HOWEVER EXPECT THESE TO DISSIPATE DURING THE MORNING. OTHERWISE...IT SHOULD REMAIN SUNNY ACROSS CENTRAL NORTH DAKOTA TODAY...WITH INCREASING CLOUDS WEST THIS AFTERNOON. WILL TAKE ANOTHER LOOK AT TEMPERATURES LATE MORNING OR EARLY AFTERNOON. UPDATE ISSUED AT 701 AM CDT FRI APR 19 2013 HIGH PRESSURE BUILDING INTO THE REGION HAS SCOURED OUT MUCH OF THE LOW-LEVEL MOISTURE ACROSS CENTRAL NORTH DAKOTA. AS A RESULT...DECREASED THE FIRST PERIOD SKY COVER ACROSS THE AFOREMENTIONED REGION. A 75+ KT 500MB JET STREAK DIVING SOUTH OVER WESTERN NORTH DAKOTA HAS GENERATED VERY NARROW SNOW BANDS WEST THIS MORNING. AS A RESULT...SHIFTED ISOLATED POPS A LITTLE FARTHER WEST BASED ON CURRENT OBS/TRENDS. THIS JET STREAK SHOULD BE OVER SOUTH DAKOTA BY MID TO LATE MORNING TAKING ANY PRECIP CHANCES WITH IT. THE REMAINED GRIDDED WEATHER ELEMENTS ARE IN GOOD SHAPE. THE UPDATED GRIDDED AND TEXT PRODUCTS HAVE BEEN SENT. && .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 334 AM CDT FRI APR 19 2013 THE FORECAST HIGHLIGHT FOR THE SHORT TERM PERIOD IS THE CONTINUED CHANCES FOR LIGHT PRECIPITATION. CURRENTLY...AN UPPER LEVEL SHORTWAVE IS DIVING SOUTHEAST OUT OF CANADA...WHILE AN AREA OF WEAK LOW PRESSURE WAS LOCATED OVER NORTHEASTERN MONTANA...WITH AN ASSOCIATED WARM FRONT DRAPED ACROSS WESTERN NORTH DAKOTA AND A TRAILING COLD FRONT OVER NORTHERN MONTANA. THE FOCUS FOR THE MID LEVEL CLOUD SHIELD AND LIGHT PRECIPITATION THIS MORNING IS IN THE VICINITY OF THE WARM FRONT. LATEST RADAR IMAGERY CONTINUES TO SHOW SCATTERED LIGHT RETURNS OVER THE WEST...WHILE SURFACE OBSERVATIONS HAVE SHOWN BRIEF PERIODS OF LIGHT SNOW. THE 00Z NAM/07Z RAP HAS THIS AREA OF LIGHT SNOW DISSIPATING IN INTENSITY THIS MORNING...AND THUS HAVE DECREASED POPS ACROSS THE CENTRAL PART OF THE STATE THIS MORNING. A BRIEF LULL IN THE LIGHT PRECIPITATION WILL BE SEEN TODAY BEFORE THE NEXT UPPER LEVEL WAVE AND ASSOCIATED SURFACE LOW PRESSURE PROGRESSES SOUTHWARD TONIGHT. THE 00Z SUITE OF MODELS ARE IN GOOD AGREEMENT THAT LIGHT PRECIPITATION IN THE FORM OF A LIGHT WINTRY MIX AND LIGHT SNOW WILL MOVE INTO THE WEST BEFORE MIDNIGHT...AND THEN SPREAD INTO THE CENTRAL AFTER MIDNIGHT. MEANWHILE...THE CONTINUED THEME OF BELOW NORMAL TEMPERATURES WILL CONTINUE. HIGHS WILL BE 10 TO 20 DEGREES BELOW NORMAL...AS HIGHS WILL WARM ONLY INTO THE LOWER 30S...EXCEPT THE SOUTHWEST WHERE MID TO UPPER 30S ARE POSSIBLE. FOR OVERNIGHT LOWS...TEMPERATURES WILL RANGE FROM THE LOWER TEENS IN THE JAMES RIVER VALLEY TO THE UPPER 20S FAR SOUTHWEST. A RECORD LOW TEMPERATURE FOR JAMESTOWN MAY BE IN JEOPARDY TONIGHT...AS THE OVERNIGHT LOW IS FORECAST TO BE 12 DEGREES AND THE RECORD LOW IS 14 DEGREES SET IN 1966. .LONG TERM...(SATURDAY THROUGH THURSDAY) ISSUED AT 334 AM CDT FRI APR 19 2013 THE MEDIUM RANGE MODELS CONTINUE TO PROG A WET WEEKEND FOR WESTERN AND CENTRAL NORTH DAKOTA. A WARM FRONT PUSHING ACROSS THE REGION WILL GENERATE CHANCE POPS SATURDAY. THE PRECIP TYPE IS EXPECTED TO GENERALLY BE A WINTRY MIX...WITH LIGHT RAIN POSSIBLE WEST WHERE THE WARMEST TEMPERATURES ALOFT WILL RESIDE. AS THE WARM FRONT SHIFTS EAST SATURDAY NIGHT...A COLD FRONT WILL ENTER WESTERN NORTH DAKOTA AFTER MIDNIGHT. THE COLD FRONT WILL GENERATE A CHANCE OF A WINTRY MIX NORTH OF I-94 AS IT PUSHES EAST ACROSS THE REGION SUNDAY. AREAS SOUTH OF I-94 ARE EXPECTED TO SEE A CHANCE OF LIGHT RAIN SUNDAY. SNOW TOTALS WILL BE IN THE 1-2 INCH RANGE NORTH...WITH MUCH LIGHTER AMOUNTS EXPECTED SOUTH AND WEST. A DRYING/WARMING TREND IS EXPECTED MONDAY THROUGH THE END OF THE PERIOD. HOWEVER...THE LATEST MEDIUM RANGE MODEL GUIDANCE NOW PROGS A WEAK COLD FRONT TO PUSH THROUGH THE REGION WEDNESDAY. THIS FEATURE IS EXPECTED TO GENERATE A SLIGHT CHANCE OF LIGHT RAIN MIXED WITH SLEET WEDNESDAY. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON) ISSUED AT 1251 PM CDT FRI APR 19 2013 LOW PRESSSURE OVER CENTRAL MONTANA WILL MOVE SLOWLY EAST INTO EASTERN MONTANA THROUGH 18Z SATURDAY. THIS WILL RESULT IN AN INCREASING SOUTHEAST FLOW OVER WESTERN NORTH DAKOTA THIS EVENING...WITH NORTH FLOW IN THE EAST TURNING SOUTHEAST LATE TONIGHT AND INCREASING ON SATURDAY. INCREASING CLOUDINESS WILL SPREAD WEST TO EAST TONIGHT...WITH MVFR CLOUDINESS AND LIGHT SNOW MOVING INTO KISN AND KDIK AROUN 12Z SATURDAY AND SPREADING INTO KMOT AND KBIS TOWARD 18Z SATURDAY. && .BIS WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...TWH SHORT TERM...LTH LONG TERM...TM AVIATION...TWH
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 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 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 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 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 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
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
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 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 SPOKANE WA
655 PM PDT Fri Apr 19 2013 .SYNOPSIS... A WEATHER SYSTEM WILL PASS THROUGH THE INLAND NORTHWEST TONIGHT BRINGING RAIN AND HIGH MOUNTAIN SNOW. SHOWERS WILL LINGER INTO THE WEEKEND EXCEPT FOR NORTH CENTRAL WASHINGTON WHICH WILL STAY GENERALLY DRY. ANOTHER COLD FRONT IS EXPECTED TO PASS THROUGH NORTHEAST WASHINGTON AND NORTH IDAHO SUNDAY FOR COOLER TEMPERATURES. A WARMING AND DRYING TREND IS LIKELY BEGINNING ON MONDAY AS HIGH PRESSURE BEGINS TO BUILD OVER THE REGION. && .DISCUSSION... Evening update to increase Pops across Northeastern Wa and Nrn ID...generally between Chewelah and Prichard including the communities of Deer Park, Priest Lake, Sandpoint, and Clark Fork. A cluster of heavier showers associated with a midlevel shortwave and modeled well by the HRRR will continue east through these areas this evening...tracking east into Montana around 5z. Under these showers, up to a tenth of an inch of rainfall will be possible. One isolated cell did spring up briefly near the town of Clayton and did have weak rotation which allowed the updraft to persist for a few scans and may have produced small hail briefly but this cell quickly collapsed shortly after. Additional showers exist across the northern mountains, lower ID Panhandle, Blue Mtns, and Cascade Crest which was captured well with the previous forecast. /sb && .AVIATION... 00Z TAFS: Upper level northwest to southeast oriented flow will continue to steer disturbances overhead of the aviation area through the next 24 hours. Result of having the jet stream in close proximity or directly overhead with some of these disturbance passages will be a significant increase in wind tomorrow after 18Z Saturday. Otherwise nuisance showers in the area may allow for brief intervals of MVFR ceilings more than visibilities at times. /Pelatti && .PRELIMINARY POINT TEMPS/POPS... Spokane 39 58 35 51 29 54 / 70 40 20 10 10 0 Coeur d`Alene 40 56 33 50 27 53 / 90 50 30 20 10 0 Pullman 38 56 33 51 28 53 / 40 30 20 40 10 0 Lewiston 43 61 39 57 33 58 / 50 20 10 40 20 0 Colville 38 61 32 54 27 57 / 30 50 30 10 10 0 Sandpoint 40 52 32 47 27 51 / 90 80 60 30 10 0 Kellogg 38 48 33 44 25 49 / 90 80 70 70 20 0 Moses Lake 42 66 37 61 30 62 / 10 10 0 10 0 0 Wenatchee 44 60 38 57 34 59 / 10 10 0 10 0 0 Omak 37 63 34 57 28 61 / 10 10 10 10 0 0 && .OTX WATCHES/WARNINGS/ADVISORIES... ID...None. WA...None. && $$
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
313 PM CDT FRI APR 19 2013 .SHORT TERM...(THIS EVENING THROUGH SATURDAY) ISSUED AT 313 PM CDT FRI APR 19 2013 MAIN FORECAST CONCERNS ARE ON LINGERING SNOW/RAIN SHOWERS THIS EVENING. FOCUS THEN TURNS TO PRECIPITATION CHANCES AND TEMPERATURES SATURDAY NIGHT INTO SUNDAY. LATEST WATER VAPOR IMAGERY AND 500 MB RAP ANALYSIS PLACED LOW PRESSURE OVER CENTRAL LAKE SUPERIOR...MOVING NORTHEAST. CYCLONIC FLOW WAS IMPACTING THE FORECAST AREA ON THE BACK SIDE OF THE LOW. THIS CYCLONIC FLOW COUPLED WITH STEEP LAPSE RATES HAS PRODUCED WIDESPREAD SNOW SHOWERS THROUGH MUCH OF THE DAY. SCATTERED SNOW SHOWERS WILL LINGER INTO THE EARLY EVENING THEN DISSIPATE AS THE LOW LIFTS NORTHEAST AND SURFACE TEMPERATURES COOL. HIGH PRESSURE WILL GRADUALLY BUILD INTO THE FORECAST AREA TONIGHT INTO EARLY SATURDAY MORNING. IT WILL TAKE SOME TIME TO SCOUR OUT THE LOW LEVEL MOISTURE AND THE NAM AND GFS HANG ONTO THIS MOISTURE WELL INTO THE EVENING HOURS. LOOKING AT OBSERVATIONS AND VISIBLE SATELLITE UPSTREAM ACROSS WESTERN INTO CENTRAL MINNESOTA THERE IS A WELL DEFINED CLEARING LINE AND A LACK OF CUMULUS DEVELOPMENT TODAY THANKS TO THE FRESH SNOW COVER IN PLACE KEEPING SURFACE TEMPERATURES COOL. PLAN ON A GRADUAL CLEARING TREND FROM WEST TO EAST TONIGHT...WITH THE CLEARING APPROACHING THE MISSISSIPPI RIVER LATE IN THE EVENING THEN PROGRESSING EAST THROUGH THE OVERNIGHT HOURS. SKIES WILL BE MOSTLY SUNNY SATURDAY MORNING AS COOL HIGH PRESSURE SLIDES OVERHEAD. THE SUNNY SKIES WILL BE SHORT LIVED ON SATURDAY AS A SHORTWAVE TROUGH APPROACHES FROM THE NORTHERN PLAINS WITH INCREASING HIGH CLOUDS EXPECTED DURING THE LATE AFTERNOON HOURS. THE HIGH WILL QUICKLY PUSH EAST OF THE REGION SATURDAY EVENING AS THE SHORTWAVE APPROACHES THE UPPER MISSISSIPPI RIVER VALLEY AND SURFACE LOW PRESSURE DEEPENS OVER THE CENTRAL/NORTHERN PLAINS. PLAN ON HIGH TEMPERATURES ON SATURDAY RANGING FROM THE UPPER 30S OVER NORTH CENTRAL WISCONSIN TO THE MID 40S ACROSS NORTHEAST IOWA. .LONG TERM...(SATURDAY NIGHT THROUGH FRIDAY) ISSUED AT 313 PM CDT FRI APR 19 2013 SOUTHERLY FLOW WILL INCREASE ACROSS THE REGION AHEAD OF THE LOW. STRONG 850MB WARM AIR ADVECTION INCREASES ACROSS THE FORECAST AREA IN THE 6Z-12Z TIMEFRAME. PLAN ON RAIN/SNOW SHOWERS DEVELOPING ACROSS THE AREA AS THIS SHORTWAVE MOVES IN AND WARM AIR ADVECTION INCREASES. FORECAST SOUNDINGS SHOW A DRY LAYER NEAR THE SURFACE...MAINLY BELOW 3KFT. AS PRECIPITATION FALLS INTO THIS LAYER...EVAPORATION WILL COOL THE LOWER LEVELS LEADING TO A SWITCH FROM RAIN INITIALLY OVER TO A PERIOD OF SNOW. SURFACE TEMPERATURES WARM IN THE 12 TO 15Z...SOUTH OF INTERSTATE 94...SO EXPECTING TO SEE A SWITCH OVER TO ALL RAIN ACROSS THESE AREAS. NORTH OF I-94 IT WILL TAKE A LITTLE LONGER FOR SURFACE TEMPERATURES TO WARM WHERE THE SWITCH OVER LOOKS TO OCCUR AFTER 17Z. A SLIGHTLY WARMER AND UNSTABLE AIRMASS MOVES INTO THE AREA SUNDAY AFTERNOON WITH 0-3 KM MUCAPE VALUES INCREASING TO AROUND 500 J/KG. COULD SEE SOME ISOLATED TO SCATTERED THUNDERSTORMS SUNDAY AFTERNOON INTO SUNDAY EVENING. THERE IS THE POTENTIAL FOR SOME SMALL HAIL WITH ANY THUNDERSTORMS THAT DEVELOP WEST OF THE MISSISSIPPI RIVER. CAPE AND SHEAR PROFILES ARE RATHER WEAK SO NOT ANTICIPATING SEVERE THUNDERSTORMS AT THIS TIME. THERE ARE SOME INDICATIONS THAT THE FRONT COULD SLIDE THROUGH LATER...PLACING THUNDERSTORM POTENTIAL OVER THE FORECAST AREA AGAIN ON MONDAY. IF THIS SCENARIO PLAYS OUT...THERE IS THE POSSIBILITY OF THUNDERSTORMS AGAIN ON MONDAY MAINLY ALONG AND SOUTH OF INTERSTATE 90. A SECONDARY TROUGH DIVES SOUTHEAST OUT OF WESTERN CANADA AND INTO THE PLAINS SUNDAY NIGHT INTO MONDAY. A COLD FRONT...STRETCHING FROM NORTHEAST MINNESOTA SOUTHWEST INTO SOUTHEASTERN SOUTH DAKOTA...WILL SLIDE SOUTHEAST SUNDAY NIGHT THROUGH MONDAY AS THE WAVE DIGS SOUTH. SOME DIFFERENCES NOTED IN THE FORECAST MODELS MONDAY INTO TUESDAY AS ANOTHER WAVE DIVES SOUTH OUT OF THE PACIFIC NORTHWEST AND INTO THE CENTRAL PLAINS. THE GFS PUSHES THE COLD FRONT SOUTH ON MONDAY AS THE SHORTWAVE EJECTS OUT OF THE CENTRAL PLAINS AND INTERACTS WITH THE FRONT OVER THE FORECAST AREA. THIS SCENARIO WOULD PRODUCE SIGNIFICANT RAINFALL AND EVEN SOME SNOW ACROSS PORTIONS OF SOUTHEAST MINNESOTA THROUGH NORTH CENTRAL WISCONSIN MONDAY NIGHT INTO TUESDAY. THE GEM SOLUTION IS ALSO ON BOARD WITH THE GFS BUT IS SLOWER WITH THE WAVE BRINGING IT INTO THE FORECAST AREA TUESDAY INTO TUESDAY NIGHT. THE 19.12 ECMWF IS MORE IN LINE WITH THE GEM SOLUTIO AND ALSO PRODUCES A SWATH OF ACCUMULATING SNOW ACROSS SOUTHEAST MINNESOTA THROUGH NORTH CENTRAL WISCONSIN WITH TEMPERATURES WARM ENOUGH FOR RAIN TO MIX IN OVER PORTIONS OF NORTHEAST IOWA INTO FAR SOUTHWEST WISCONSIN. GIVEN THE UNCERTAINTIES IN THE TRACK AND TINNING OF THIS SYSTEM ITS DIFFICULT TO PIN DOWN EXACT PRECIPITATION TYPE AND AMOUNTS. WILL HAVE TO KEEP A VERY CLOSE WATCH ON THIS SYSTEM IMPACTING THE REGION IN THE MONDAY THROUGH WEDNESDAY TIMEFRAME. WELL BELOW NORMAL TEMPERATURES ARE EXPECTED THE LAST HALF OF THE WORK WEEK AS NORTHWEST FLOW ALOFT SETS UP OVER THE REGION. AFTER A BRIEF RETURN TO SLIGHTLY MORE SEASONABLE TEMPERATURES SUN-MON WITH HIGHS IN THE 50S...HIGHS WILL FALL BACK INTO THE 40S TO AROUND 50 WEDNESDAY INTO THURSDAY. THE ACTIVE PATTERN CONTINUES THURSDAY INTO FRIDAY AS ANOTHER TROUGH TAKES AIM ON THE REGION VIA NORTHWEST FLOW ALOFT. THIS FEATURE WILL BRING RAIN AND SNOW CHANCES TO THE AREA ON THURSDAY. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SATURDAY AFTERNOON) ISSUED AT 1206 PM CDT FRI APR 19 2013 CYCLONIC FLOW AROUND THE SURFACE LOW OVER LAKE SUPERIOR CONTINUES TO GENERATE WIDESPREAD CLOUDS AND SOME SNOW SHOWERS ACROSS THE AREA. EXPECT THIS TREND TO CONTINUE FOR THE REMAINDER OF THE AFTERNOON INTO THE EVENING. THE CYCLONIC FLOW AND LOW LEVEL INSTABILITY SHOULD WEAKEN ENOUGH BY MID EVENING TO ALLOW THE SHOWERS TO DISSIPATE WITH THE WINDS DIMINISHING AS WELL. UNTIL THIS HAPPENS...CEILINGS AND VISIBILITY EXPECTED TO PRIMARILY BE VFR ALTHOUGH THERE WILL BE SOME SHORT PERIODS WHEN A SNOW SHOWER COULD REDUCE THE VISIBILITY AND CEILINGS TO MVFR. BACK EDGE OF THE CLOUDS ACROSS NORTHWEST MINNESOTA HAS BEEN MOVING STEADILY SOUTHEAST AND EXTRAPOLATION OF THIS TIMING WOULD BRING THE CLEARING INTO KRST AROUND 04Z OR SO AND KLSE AROUND 07Z. THIS TREND WAS ALREADY IN THE PREVIOUS FORECAST BUT JUST MOVED THE TIMING UP AT KRST A LITTLE BIT. SKIES SHOULD THEN GO CLEAR OVERNIGHT WITH SOME DIURNAL CUMULUS EXPECTED TO FORM LATE SATURDAY MORNING. NOT ENOUGH OF A CHANGE IN THE FORECAST TO INCLUDE THESE TRENDS AT THIS TIME. && .HYDROLOGY... ISSUED AT 313 PM CDT FRI APR 19 2013 FLOODING IS CURRENTLY OCCURRING ALONG PORTIONS OF THE BLACK RIVER. PORTIONS OF THE TREMPEALEAU RIVER ARE RUNNING NEAR OR SLIGHTLY ABOVE FLOOD STAGE. RECENT RAINFALL WILL KEEP THESE RIVERS NEAR OR ABOVE FLOOD STAGE THROUGH THE WEEKEND. WET CONDITIONS WILL PERSIST INTO THE EARLY PART OF THE WORK WEEK. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...NONE. MN...NONE. IA...NONE. && $$ SHORT TERM...WETENKAMP LONG TERM...WETENKAMP AVIATION...04 HYDROLOGY...WETENKAMP
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
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 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 TAUNTON MA
428 AM EDT SAT APR 20 2013 .SYNOPSIS... WIDESPREAD RAIN WITH EMBEDDED HEAVIER SHOWERS WILL CONTINUE INTO THE MORNING HOURS AS A COLD FRONT GRADUALLY SWEEPS ACROSS THE AREA AND OFFSHORE. STRONG SOUTHERLY WINDS WITH GUSTS UP TO 35 MPH CAN BE EXPECTED AHEAD OF THE FRONT...BACKING OUT OF THE WEST IN WAKE WITH CONTINUED GUSTS AROUND 25 MPH. COLDER AND DRIER AIR WILL ADVECT INTO THE REGION FOR THE REMAINDER OF THIS WEEKEND INTO THE EARLY PART OF NEXT WEEK. A DEVELOPING COASTAL STORM WILL BRING SHOWERS AROUND TUESDAY...THEN ANOTHER COLD FRONT MOVES THROUGH LATER IN THE WEEK. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... INTO THE MORNING... WIDESPREAD RAIN CONTINUES WITH EMBEDDED HEAVIER SHOWERS. HAVE REMOVED ALL MENTION OF THUNDER. WINDS HAVE BEGUN TO SLACKEN LIKELY AS A RESULT OF BOUNDARY LAYER DECOUPLING. GUSTS UP TO 35 MPH ARE ONLY ANTICIPATED ACROSS THE SOUTHEASTERN FORECAST AREA AND ACROSS THE ADJACENT WATERS. CONTINUED BLEND OF NEAR-TERM MESOSCALE GUIDANCE OF THE WRF AND RAP HAS DONE IMPRESSIVELY WELL IN HANDLING THE PARTICULAR OUTCOMES. TODAY... SHOWERS AND CLOUDS LINGER ACROSS SOUTHEASTERN MASSACHUSETTS AND THE ADJACENT WATERS DURING THE MORNING HOURS...GRADUALLY CLEARING INTO MIDDAY. SOUTHWEST GUSTS CONTINUING AHEAD OF THE FRONT BACKING OUT OF THE WEST AND USHERING COOLER AND DRIER AIR INTO THE REGION ASSOCIATED WITH HIGH PRESSURE. THIS WILL ALLOW THE BOUNDARY LAYER TO BECOME WELL-MIXED UP TO H8 ALLOWING THE MIX-DOWN OF DRIER AIR AND FASTER MOMENTUM. SO THE EXPECTATION FOR THE DAY IS HIGHS AROUND THE UPPER 50S TO LOW 60S WITH WESTERLY WINDS GUSTING AROUND 25 MPH. SHOULD SEE A MIX-OUT OF RESIDUAL MOISTURE OF THE PREVIOUS EVENINGS RAINS ALLOWING FOR SCATTERED TO BROKEN DIURNAL CUMULUS. THIS COULD POTENTIAL HAVING ADVERSE AFFECT ON SURFACE TEMPERATURES RESULTING IN COOLER VALUES THAN PRESENTLY FORECAST. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM SUNDAY/... TONIGHT... WEST-NORTHWEST FLOW CONTINUING YET GRADUALLY DYING DOWN AS CONDITIONS GRADUALLY CLEAR. EXPECTING TEMPERATURES TO FALL DOWN TO THE FREEZING MARK WITH LOWS INTO THE UPPER 20S ACROSS THE CENTRAL INTERIOR AND HIGHER ELEVATIONS. SHOULD SHELTERED VALLEY LOCALES BECOME CALM...THERE IS THE POTENTIAL FOR EFFECTIVE RADIATIONAL COOLING ALLOWING COLDER CONDITIONS. THE EXPECTATION FOR IS A VERY DRY COLUMN EARLIER IN THE DAY CONTINUING OVERNIGHT...SO HAVE LOW EXPECTATIONS FOR FOG. SUNDAY... HIGH PRESSURE IN CONTROL WITH MOSTLY CLEAR CONDITIONS. LIGHT AND VARIABLE WINDS UNDER A CONTINUED COOL AND DRY AIRMASS. ANTICIPATING SEA-BREEZES ALONG THE IMMEDIATE SHORES AS HIGHS WILL GET UP INTO THE MID TO UPPER 50S /COOLER ALONG THE SHORES CONSEQUENTIAL OF SEA- BREEZES/. && .LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/... BIG PICTURE... UPPER RIDGE SHIFTS OVER THE WESTERN ATLANTIC. SECOND UPPER RIDGE TAKES UP POSITION OFF THE PACIFIC COAST. THIS MAKES ROOM FOR A BROAD TROUGH TO DIG OVER THE INTERIOR USA. A SHORTWAVE IN THIS BROAD FLOW MOVES FROM THE PACIFIC NORTHWEST TO THE SOUTHERN USA OVER THIS WEEKEND...THEN GENERATES A INVERTED TROUGH AT THE SURFACE OFF THE CAROLINA COAST. THIS FULL COMPLEX MOVES PAST NEW ENGLAND WEDNESDAY. ANOTHER BETTER DEFINED SHORTWAVE DIVES SOUTH FROM NORTHERN CANADA INTO THE INTERIOR USA TROUGH AND THEN SWINGS ACROSS NEW ENGLAND LATE NEXT WEEK. UPPER JET OVER NEW ENGLAND MOVES NORTHEAST PAST GREENLAND/ICELAND. ANOTHER JET SEGMENT TRACES THE PACIFIC NORTHWEST/SOUTHERN ROCKIES. THIS EVENTUALLY SWINGS NORTHEAST THROUGH THE GREAT LAKES MIDWEEK AND THE NORTHEAST USA LATE WEEK. MODEL PREFERENCES... SMALL DIFFERENCE IN GFS AND ECMWF UPPER CONTOUR FIELDS REGARDING COASTAL SYSTEM NEXT WEEK. OTHERWISE THE LONG RANGE MODELS ARE IN GOOD AGREEMENT SURFACE AND ALOFT. WE USED A BLEND OF 20/00Z GFS/ECMWF VALUES...AND BLEND WITH GRIDDED MOS/HPC GRIDS WHERE AVAILABLE. THE DAILIES... SUNDAY NIGHT-MONDAY... HIGH PRESSURE MOVES OFFSHORE MONDAY. GENERALLY FAIR WEATHER WITH INCREASING CIRRUS DURING MONDAY. TEMPERATURES ALOFT RISE A LITTLE MONDAY...BUT THE BUFFERING OF THE INCREASED EAST FLOW SHOULD BALANCE ANY WARMING AND KEEP HIGH TEMPERATURES SIMILAR TO SUNDAY. MONDAY NIGHT-TUESDAY... INVERTED TROUGH/DEVELOPING COASTAL LOW WILL START PUSHING DEEPER MOISTURE UP THE COAST. ALL MODEL PRECIPITATION FORECASTS ARE WELL SOUTH OF NEW ENGLAND MONDAY EVENING...BUT MOVE MEASURABLE PCPN INTO THE AREA...ESPECIALLY THE SOUTH COAST...AFTER 06Z/2 AM. 20/00Z GFS IS FARTHER EAST THAN THE OTHER MEMBERS OF THE 20/00Z GUIDANCE SUITE. THIS LOOKS SUSPICIOUS WITH SUCH A STRONG HIGH PRESSURE ANCHORED OVER THE MARITIMES. AS SUCH...FAVORED THE MORE WESTERN CONSENSUS TRACK LED BY THE ECMWF. BASED ON THAT TRACK... INCREASED POPS TO LIKELY ACROSS EASTERN MA TUESDAY...WITH CHANCE POPS TUESDAY NIGHT AS THIS SYSTEM PULLS AWAY. WEDNESDAY-THURSDAY... PLAINS/GREAT LAKES TROUGH AND SUPPORTING UPPER JET MOVE UP THE ST LAWRENCE VALLEY INTO CANADA. THIS FEATURE WILL SUPPORT A COLD FRONT THAT WILL SWING THROUGH NEW ENGLAND WEDNESDAY NIGHT- THURSDAY. ON WEDNESDAY POPS SHOW A BRIEF BREAK AFTER A COASTAL SYSTEM MOVES OFF...BUT THEN A RESUMPTION OF CHANCE POPS AS THE GREAT LAKES COLD FRONT MOVES THROUGH. THE DEPICTION OF TWO DISTINCT SYSTEMS IS REASONABLE GIVEN THAT ONE IS SOUTHERN STREAM AND THE OTHER IS NORTHERN STREAM...BUT THE DISTINCTNESS/LENGTH OF TIME BETWEEN THE TWO PCPN SHIELDS IS LESS CERTAIN. FRIDAY... HIGH PRESSURE BUILDS AT THE SURFACE WHILE THE SUPPORTING UPPER TROUGH FROM THURSDAY/S FRONT WILL STILL BE IN THE NEIGHBORHOOD. NO DESTABILIZATION EXPECTED AS UPPER TEMPERATURES SHOW LITTLE CHANGE AND MOISTURE IS LIMITED. EXPECTING A DRY DAY WITH SIMILAR MAX/MIN TEMPERATURES TO THURSDAY. && .AVIATION /08Z SATURDAY THROUGH WEDNESDAY/... FORECASTER CONFIDENCE LEVELS... LOW...LESS THAN 30 PERCENT. MODERATE...30 TO 60 PERCENT. HIGH...GREATER THAN 60 PERCENT. OVERVIEW... * MODERATE CONFIDENCE INTO SATURDAY MORNING... * HIGH CONFIDENCE SATURDAY AFTERNOON INTO SUNDAY... A MIX OF MVFR-IFR CIGS AND VSBYS CONTINUE WITH THE BROAD AREA OF RAIN WITH EMBEDDED HEAVIER SHOWERS. ALREADY BEGINNING TO SEE WINDS BACKING OUT OF THE WEST-NORTHWEST WITH THE COLD FRONTAL PASSAGE INTO THE CONNECTICUT RIVER VALLEY...THOUGH CIGS ARE SLOW TO LIFT. WHILE DIFFICULTIES PERSIST IN TIMING OF IMPROVEMENT WEST TO EAST...HAVE CONFIDENCE CONCERNING THE OVERALL TREND THAT VSBYS WILL QUICKLY IMPROVE BEHIND THE COLD FRONT AND CIGS WILL GRADUALLY LIFT. WINDS WILL BACK OUT OF THE WEST-NORTHWEST WITH GUSTS UP TO 25 KTS WITH SCT-BKN DIURNAL CU DURING TODAY. IMPROVING TO VFR. INTO THE EVENING AND ON INTO SUNDAY...WINDS SHOULD BECOME LIGHT AND VARIABLE. SEA-BREEZE LIKELY TO IMPACT COASTAL TERMINALS. WILL NEED TO MONITOR CLOSELY FOR THE DEVELOPMENT OF FOG OVERNIGHT IN LOW LYING LOCATIONS AS MUCH COLDER AIR SETTLES INTO THE REGION. MOSTLY CLEAR CONDITIONS. VFR. KBOS TERMINAL...MODERATE CONFIDENCE. WHILE FAIRLY CERTAIN ON TRENDS...THE TIMING OF IMPACTS OVER THE NEXT SEVERAL HOURS COUPLED WITH IMPROVEMENT REMAINS CHALLENGING. COULD SEE SEA-BREEZE IMPACTS ON SUNDAY. KBDL TERMINAL...MODERATE CONFIDENCE. GRADUAL IMPROVEMENT SHOULD BEGIN AS THE COLD FRONT HAS SWEPT ACROSS THE TERMINAL...THE TIMING OF WHICH REMAINS TRICKY. COULD SEE SOME FOG IMPACTS SATURDAY NIGHT INTO SUNDAY MORNING. OUTLOOK...SUNDAY THROUGH WEDNESDAY... SUNDAY NIGHT-MONDAY...VFR. LIGHT WINDS SUNDAY NIGHT. INCREASING EAST WINDS MONDAY WITH GUSTS TO 25 KNOTS ALONG THE CAPE AND ISLANDS/SOUTH COAST. HIGH CONFIDENCE. MONDAY NIGHT-TUESDAY...CONDITIONS LOWERING LATER MONDAY NIGHT WITH MVFR/IFR CIGS/VSBY POSSIBLE TUESDAY ESPECIALLY RI AND SOUTHEAST MASS. MODERATE CONFIDENCE. WEDNESDAY...CONDITIONS IMPROVING TO VFR DURING THE MORNING AND AFTERNOON AS TUESDAY/S STORM MOVES OFF. A COLD FRONT APPROACHES LATE IN THE DAY...BUT EFFECTS MAY HOLD OFF UNTIL WEDNESDAY NIGHT WHEN CONDITIONS MAY LOWER TO MVFR/IFR IN SHOWERS/SCATTERED TSTMS. MODERATE CONFIDENCE. && .MARINE... FORECASTER CONFIDENCE LEVELS... LOW...LESS THAN 30 PERCENT. MODERATE...30 TO 60 PERCENT. HIGH...GREATER THAN 60 PERCENT. OVERVIEW...MODERATE CONFIDENCE THROUGH SUNDAY. GALE WARNINGS WILL CONTINUE FOR A BRIEF PERIOD THIS MORNING... REVERTING TO SMALL CRAFT ADVISORIES AS WINDS GRADUALLY RELAX BELOW 35 KTS. THE EXPECTATION IS FOR WESTERLY FLOW BEHIND A COLD FRONT WHICH WILL SWEEP ACROSS THE WATERS THIS MORNING INTO MIDDAY TO GUST UP TO 25 KTS AND KEEP SEAS IN EXCESS OF 5 FEET /UP TO 10 FEET ON THE OUTER WATERS/. ANTICIPATE WIDESPREAD RAIN WITH EMBEDDED HEAVIER SHOWERS RESULTING IN SOME MINOR VISIBILITY IMPACTS AHEAD OF THE COLD FRONT. WINDS AND SEAS ARE ANTICIPATED TO FALL BELOW SMALL CRAFT ADVISORY THRESHOLDS ON SUNDAY AS HIGH PRESSURE SETTLES ACROSS THE REGION. OUTLOOK...SUNDAY NIGHT THROUGH WEDNESDAY... HIGH CONFIDENCE SUNDAY TO TUESDAY. MODERATE CONFIDENCE WEDNESDAY. MONDAY...INCREASING EAST WIND WITH POTENTIAL WIND GUSTS TO 25 KT AND SEAS 5 FEET OR HIGHER IN THE AFTERNOON AND AT NIGHT... ESPECIALLY ACROSS THE SOUTHERN WATERS. SMALL CRAFT ADVISORIES LIKELY...ESPECIALLY FOR THE OUTER COASTAL WATERS. TUESDAY...SEAS AT OR ABOVE 5 FEET ACROSS THE OPEN WATERS. EAST WINDS GUSTING AROUND 25 KT. SMALL CRAFT ADVISORIES LIKELY. WEDNESDAY...A SHORT BREAK BETWEEN WEATHER SYSTEMS. WINDS GENERALLY BELOW 25 KT...BUT MAY INCREASE TO NEAR 25 KT ACROSS THE EASTERN WATERS LATE IN THE DAY. SEAS UP TO 7 FEET...MAINLY ACROSS THE OUTER WATERS. && .BOX WATCHES/WARNINGS/ADVISORIES... CT...NONE. MA...NONE. NH...NONE. RI...NONE. MARINE...GALE WARNING UNTIL 6 AM EDT EARLY THIS MORNING FOR ANZ231>234- 250-251. SMALL CRAFT ADVISORY UNTIL 8 AM EDT THIS MORNING FOR ANZ230- 236. SMALL CRAFT ADVISORY UNTIL 8 AM EDT SUNDAY FOR ANZ235-237. GALE WARNING UNTIL 8 AM EDT THIS MORNING FOR ANZ254-255. SMALL CRAFT ADVISORY UNTIL 2 PM EDT SUNDAY FOR ANZ256. && $$ SYNOPSIS...SIPPRELL/BELK NEAR TERM...SIPPRELL SHORT TERM...SIPPRELL LONG TERM...BELK AVIATION...SIPPRELL/BELK MARINE...SIPPRELL/BELK
AREA FORECAST DISCUSSION
NWS TAUNTON MA
341 AM EDT SAT APR 20 2013 .SYNOPSIS... WIDESPREAD RAIN WITH EMBEDDED HEAVIER SHOWERS WILL CONTINUE INTO THE MORNING HOURS AS A COLD FRONT GRADUALLY SWEEPS ACROSS THE AREA AND OFFSHORE. STRONG SOUTHERLY WINDS WITH GUSTS UP TO 35 MPH CAN BE EXPECTED AHEAD OF THE FRONT...BACKING OUT OF THE WEST IN WAKE WITH CONTINUED GUSTS AROUND 25 MPH. COLDER AND DRIER AIR WILL ADVECT INTO THE REGION FOR THE REMAINDER OF THE WEEKEND INTO THE EARLY PART OF NEXT WEEK. A DEVELOPING COASTAL STORM WILL BRING SHOWERS AROUND TUESDAY...THEN ANOTHER COLD FRONT MOVES THROUGH LATER IN THE WEEK. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... INTO THE MORNING... WIDESPREAD RAIN CONTINUES WITH EMBEDDED HEAVIER SHOWERS. HAVE REMOVED ALL MENTION OF THUNDER. WINDS HAVE BEGUN TO SLACKEN LIKELY AS A RESULT OF BOUNDARY LAYER DECOUPLING. GUSTS UP TO 35 MPH ARE ONLY ANTICIPATED ACROSS THE SOUTHEASTERN FORECAST AREA AND ACROSS THE ADJACENT WATERS. CONTINUED BLEND OF NEAR-TERM MESOSCALE GUIDANCE OF THE WRF AND RAP HAS DONE IMPRESSIVELY WELL IN HANDLING THE PARTICULAR OUTCOMES. TODAY... SHOWERS AND CLOUDS LINGER ACROSS SOUTHEASTERN MASSACHUSETTS AND THE ADJACENT WATERS DURING THE MORNING HOURS...GRADUALLY CLEARING INTO MIDDAY. SOUTHWEST GUSTS CONTINUING AHEAD OF THE FRONT BACKING OUT OF THE WEST AND USHERING COOLER AND DRIER AIR INTO THE REGION ASSOCIATED WITH HIGH PRESSURE. THIS WILL ALLOW THE BOUNDARY LAYER TO BECOME WELL-MIXED UP TO H8 ALLOWING THE MIX-DOWN OF DRIER AIR AND FASTER MOMENTUM. SO THE EXPECTATION FOR THE DAY IS HIGHS AROUND THE UPPER 50S TO LOW 60S WITH WESTERLY WINDS GUSTING AROUND 25 MPH. SHOULD SEE A MIX-OUT OF RESIDUAL MOISTURE OF THE PREVIOUS EVENINGS RAINS ALLOWING FOR SCATTERED TO BROKEN DIURNAL CUMULUS. THIS COULD POTENTIAL HAVING ADVERSE AFFECT ON SURFACE TEMPERATURES RESULTING IN COOLER VALUES THAN PRESENTLY FORECAST. && .SHORT TERM /6 PM THIS EVENING THROUGH 6 PM SUNDAY/... TONIGHT... WEST-NORTHWEST FLOW CONTINUING YET GRADUALLY DYING DOWN AS CONDITIONS GRADUALLY CLEAR. EXPECTING TEMPERATURES TO FALL DOWN TO THE FREEZING MARK WITH LOWS INTO THE UPPER 20S ACROSS THE CENTRAL INTERIOR AND HIGHER ELEVATIONS. SHOULD SHELTERED VALLEY LOCALES BECOME CALM...THERE IS THE POTENTIAL FOR EFFECTIVE RADIATIONAL COOLING ALLOWING COLDER CONDITIONS. THE EXPECTATION FOR IS A VERY DRY COLUMN EARLIER IN THE DAY CONTINUING OVERNIGHT...SO HAVE LOW EXPECTATIONS FOR FOG. SUNDAY... HIGH PRESSURE IN CONTROL WITH MOSTLY CLEAR CONDITIONS. LIGHT AND VARIABLE WINDS UNDER A CONTINUED COOL AND DRY AIRMASS. ANTICIPATING SEA-BREEZES ALONG THE IMMEDIATE SHORES AS HIGHS WILL GET UP INTO THE MID TO UPPER 50S /COOLER ALONG THE SHORES CONSEQUENTIAL OF SEA- BREEZES/. && .LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/... BIG PICTURE... UPPER RIDGE SHIFTS OVER THE WESTERN ATLANTIC. SECOND UPPER RIDGE TAKES UP POSITION OFF THE PACIFIC COAST. THIS MAKES ROOM FOR A BROAD TROUGH TO DIG OVER THE INTERIOR USA. SHORTWAVE IN THIS BROAD FLOW MOVES FROM THE PACIFIC NORTHWEST TO THE SOUTHERN USA OVER THE WEEKEND...THEN GENERATES A INVERTED TROUGH AT THE SURFACE OFF THE CAROLINA COAST. THE FULL COMPLEX MOVES PAST NEW ENGLAND WEDNESDAY. ANOTHER BETTER DEFINED SHORTWAVE DIVES SOUTH FROM NORTHERN CANADA INTO THE INTERIOR USA TROUGH AND THEN SWINGS ACROSS NEW ENGLAND LATE WEEK. UPPER JET OVER NEW ENGLAND MOVES NORTHEAST PAST GREENLAND/ICELAND. ANOTHER JET SEGMENT TRACES THE PACIFIC NORTHWEST/SOUTHERN ROCKIES...THIS EVENTUALLY SWINGS NORTHEAST THROUGH THE GREAT LAKES MIDWEEK AND THE NORTHEAST USA LATE WEEK. MODEL PREFERENCES... SMALL DIFFERENCE IN GFS AND ECMWF UPPER CONTOUR FIELDS REGARDING COASTAL SYSTEM NEXT WEEK. OTHERWISE THE LONG RANGE MODELS ARE IN GOOD AGREEMENT SURFACE AND ALOFT. WE USED A BLEND OF GFS/ECMWF VALUES...AND BLEND WITH GMOS/HPC GRIDS WHERE AVAILABLE. THE DAILIES... SUNDAY-MONDAY... HIGH PRESSURE BUILDS OVER THE REGION SUNDAY AND THEN MOVES OFFSHORE MONDAY. GENERALLY FAIR WEATHER WITH INCREASING CIRRUS DURING MONDAY. AS WIND FIELDS LIGHTEN SUNDAY AFTERNOON THERE WILL BE THE POTENTIAL FOR A SEA BREEZE. THE OVERALL GRADIENT FLOW THEN SUPPORTS AN EAST FLOW ON MONDAY. TEMPS IN THE MIXED LAYER WILL BE -3C TO -5C SUNDAY WHICH WOULD SUPPORT 50S AT THE SURFACE. CLEAR SKIES AND LIGHT WINDS WILL ALLOW RADIATIONAL COOLING SUNDAY NIGHT...WITH DEWPOINTS IN THE 20S THAT SHOULD ALLOW FOR MIN TEMPS IN THE 20S AND LOWER 30S EXCEPT A LITTLE MILDER ALONG THE COAST. TEMPS ALOFT WARM A LITTLE ON MONDAY...BUT THE BUFFERING OF THE INCREASED EAST FLOW SHOULD BALANCE OFF ANY WARMING. MONDAY NIGHT-TUESDAY... INVERTED TROUGH/DEVELOPING COASTAL LOW WILL START PUSHING DEEPER MOISTURE UP THE COAST. ALL MODEL PCPN FORECASTS ARE WELL SOUTH OF NEW ENGLAND MONDAY EVENING BUT MOVE MEASURABLE PCPN INTO THE AREA...ESPECIALLY THE SOUTH COAST...AFTER 06Z/2AM. WE SLOWED THE HOURLY POP VALUES A FEW HOURS BASED ON THIS MODEL AGREEMENT. NEW ENGLAND IS IN THE RIGHT ENTRANCE REGION OF THE DEPARTING UPPER JET THROUGH TUESDAY SO DEVELOPMENT AND PCPN ARE REASONABLE. CHANCE POPS UNTIL THE SURFACE LOW/UPPER SHORTWAVE MOVE PAST ON TUESDAY NIGHT. WEDNESDAY-THURSDAY... PLAINS/GREAT LAKES TROUGH AND SUPPORTING UPPER JET MOVE UP THE ST LAWRENCE VALLEY INTO CANADA. THIS FEATURE WILL SUPPORT A COLD FRONT THAT WILL SWING THROUGH NEW ENGLAND WEDNESDAY NIGHT- THURSDAY. ON WEDNESDAY POPS SHOW A BREAK AFTER THE COASTAL SYSTEM MOVES OFF...BUT THEN A RESUMPTION OF CHANCE POPS AS THE GREAT LAKES COLD FRONT MOVES THROUGH. THE DEPICTION OF TWO DISTINCT SYSTEMS IS REASONABLE GIVEN THAT ONE IS SOUTHERN STREAM AND THE OTHER IS NORTHERN STREAM...BUT THE DISTINCTNESS/LENGTH OF TIME BETWEEN THE TWO PCPN SHIELDS IS LESS CERTAIN. FRIDAY... HIGH PRESSURE BUILDS AT THE SURFACE WHILE THE SUPPORTING UPPER TROUGH FROM THURSDAY/S FRONT WILL STILL BE IN THE NEIGHBORHOOD. NO DESTABILIZING EXPECTED AS UPPER TEMPS SHOW LITTLE CHANGE AND MOISTURE IS LIMITED. EXPECT A DRY DAY WITH SIMILAR MAX/MIN TEMPS. && .AVIATION /08Z SATURDAY THROUGH WEDNESDAY/... FORECASTER CONFIDENCE LEVELS... LOW...LESS THAN 30 PERCENT. MODERATE...30 TO 60 PERCENT. HIGH...GREATER THAN 60 PERCENT. OVERVIEW... * MODERATE CONFIDENCE INTO SATURDAY MORNING... * HIGH CONFIDENCE SATURDAY AFTERNOON INTO SUNDAY... A MIX OF MVFR-IFR CIGS AND VSBYS CONTINUE WITH THE BROAD AREA OF RAIN WITH EMBEDDED HEAVIER SHOWERS. ALREADY BEGINNING TO SEE WINDS BACKING OUT OF THE WEST-NORTHWEST WITH THE COLD FRONTAL PASSAGE INTO THE CONNECTICUT RIVER VALLEY...THOUGH CIGS ARE SLOW TO LIFT. WHILE DIFFICULTIES PERSIST IN TIMING OF IMPROVEMENT WEST TO EAST...HAVE CONFIDENCE CONCERNING THE OVERALL TREND THAT VSBYS WILL QUICKLY IMPROVE BEHIND THE COLD FRONT AND CIGS WILL GRADUALLY LIFT. WINDS WILL BACK OUT OF THE WEST-NORTHWEST WITH GUSTS UP TO 25 KTS WITH SCT-BKN DIURNAL CU DURING TODAY. IMPROVING TO VFR. INTO THE EVENING AND ON INTO SUNDAY...WINDS SHOULD BECOME LIGHT AND VARIABLE. SEA-BREEZE LIKELY TO IMPACT COASTAL TERMINALS. WILL NEED TO MONITOR CLOSELY FOR THE DEVELOPMENT OF FOG OVERNIGHT IN LOW LYING LOCATIONS AS MUCH COLDER AIR SETTLES INTO THE REGION. MOSTLY CLEAR CONDITIONS. VFR. KBOS TERMINAL...MODERATE CONFIDENCE. WHILE FAIRLY CERTAIN ON TRENDS...THE TIMING OF IMPACTS OVER THE NEXT SEVERAL HOURS COUPLED WITH IMPROVEMENT REMAINS CHALLENGING. COULD SEE SEA-BREEZE IMPACTS ON SUNDAY. KBDL TERMINAL...MODERATE CONFIDENCE. GRADUAL IMPROVEMENT SHOULD BEGIN AS THE COLD FRONT HAS SWEPT ACROSS THE TERMINAL...THE TIMING OF WHICH REMAINS TRICKY. COULD SEE SOME FOG IMPACTS SATURDAY NIGHT INTO SUNDAY MORNING. OUTLOOK...SUNDAY THROUGH WEDNESDAY... SUNDAY NIGHT-MONDAY...VFR. LIGHT WINDS SUNDAY NIGHT. INCREASING EAST WINDS MONDAY WITH GUSTS TO 25 KNOTS ALONG THE CAPE AND ISLANDS/SOUTH COAST. HIGH CONFIDENCE. MONDAY NIGHT-TUESDAY...CONDITIONS LOWERING LATER MONDAY NIGHT WITH MVFR/IFR CIGS/VSBY POSSIBLE TUESDAY ESPECIALLY RI AND SOUTHEAST MASS. MODERATE CONFIDENCE. WEDNESDAY...CONDITIONS IMPROVING TO VFR DURING THE MORNING AND AFTERNOON AS TUESDAY/S STORM MOVES OFF. A COLD FRONT APPROACHES LATE IN THE DAY...BUT EFFECTS MAY HOLD OFF UNTIL WEDNESDAY NIGHT WHEN CONDITIONS MAY LOWER TO MVFR/IFR IN SHOWERS/SCATTERED TSTMS. LOW TO MODERATE CONFIDENCE. && .MARINE... FORECASTER CONFIDENCE LEVELS... LOW...LESS THAN 30 PERCENT. MODERATE...30 TO 60 PERCENT. HIGH...GREATER THAN 60 PERCENT. OVERVIEW...MODERATE CONFIDENCE THROUGH SUNDAY. GALE WARNINGS WILL CONTINUE FOR A BRIEF PERIOD THIS MORNING... REVERTING TO SMALL CRAFT ADVISORIES AS WINDS GRADUALLY RELAX BELOW 35 KTS. THE EXPECTATION IS FOR WESTERLY FLOW BEHIND A COLD FRONT WHICH WILL SWEEP ACROSS THE WATERS THIS MORNING INTO MIDDAY TO GUST UP TO 25 KTS AND KEEP SEAS IN EXCESS OF 5 FEET /UP TO 10 FEET ON THE OUTER WATERS/. ANTICIPATE WIDESPREAD RAIN WITH EMBEDDED HEAVIER SHOWERS RESULTING IN SOME MINOR VISIBILITY IMPACTS AHEAD OF THE COLD FRONT. WINDS AND SEAS ARE ANTICIPATED TO FALL BELOW SMALL CRAFT ADVISORY THRESHOLDS ON SUNDAY AS HIGH PRESSURE SETTLES ACROSS THE REGION. OUTLOOK...SUNDAY THROUGH WEDNESDAY... MODERATE CONFIDENCE SUNDAY TO TUESDAY. LOW TO MODERATE CONFIDENCE WEDNESDAY. SUNDAY...DIMINISHING WIND. LINGERING 5 FOOT SEAS EARLY ON THE OUTER WATERS...SUBSIDING. MONDAY...INCREASING EAST WIND WITH POTENTIAL SMALL CRAFT WIND GUSTS TO 25 KNOTS AND SEAS 5 FEET OR HIGHER IN THE AFTERNOON AND AT NIGHT ESPECIALLY ON THE SOUTHERN WATERS. TUESDAY...SEAS AT OR ABOVE 5 FEET ON THE OPEN WATERS. EAST WINDS GUSTING AROUND 25 KNOTS. SMALL CRAFT ADVISORY LIKELY. SHOWERS. WEDNESDAY...A SHORT BREAK BETWEEN WEATHER SYSTEMS. WINDS GENERALLY BELOW 25 KNOTS...BUT MAY INCREASE TO NEAR 25 KNOTS ON THE EASTERN WATERS LATE IN THE DAY. SEAS 5-6 FEET MAINLY ON THE OUTER WATERS. && .BOX WATCHES/WARNINGS/ADVISORIES... CT...NONE. MA...NONE. NH...NONE. RI...NONE. MARINE...GALE WARNING UNTIL 6 AM EDT EARLY THIS MORNING FOR ANZ231>234- 250-251. SMALL CRAFT ADVISORY UNTIL 8 AM EDT THIS MORNING FOR ANZ230- 236. SMALL CRAFT ADVISORY UNTIL 8 AM EDT SUNDAY FOR ANZ235-237. GALE WARNING UNTIL 8 AM EDT THIS MORNING FOR ANZ254-255. SMALL CRAFT ADVISORY UNTIL 2 PM EDT SUNDAY FOR ANZ256. && $$ SYNOPSIS...WTB/SIPPRELL NEAR TERM...SIPPRELL SHORT TERM...SIPPRELL LONG TERM...WTB AVIATION...WTB/BELK/SIPPRELL MARINE...WTB/SIPPRELL
AREA FORECAST DISCUSSION
NWS TAUNTON MA
158 AM EDT SAT APR 20 2013 .SYNOPSIS... WIDESPREAD RAIN WITH EMBEDDED HEAVIER SHOWERS AND THE POSSIBILITY OF ISOLATED THUNDERSTORMS WILL CONTINUE INTO THE MORNING HOURS AS A COLD FRONT GRADUALLY SWEEPS ACROSS THE AREA AND OFFSHORE. STRONG SOUTHERLY WINDS WITH GUSTS UP TO 40 MPH CAN BE EXPECTED AHEAD OF THE FRONT...BACKING OUT OF THE WEST IN WAKE WITH CONTINUED GUSTS AROUND 25 MPH. COLDER AND DRIER AIR WILL ADVECT INTO THE REGION FOR THE REMAINDER OF THE WEEKEND INTO THE EARLY PART OF NEXT WEEK. A DEVELOPING COASTAL STORM WILL BRING SHOWERS AROUND TUESDAY...THEN ANOTHER COLD FRONT MOVES THROUGH LATER IN THE WEEK. && .NEAR TERM /UNTIL 6 AM THIS MORNING/... 2 AM UPDATE... IT HAS BEEN QUITE A BUSY NIGHT. CONTINUE TO MONITOR WIDESPREAD RAIN WITH EMBEDDED HEAVIER SHOWERS. HAVE DIMINISHED THUNDERSTORM POSSIBILITIES WITHIN THE FORECAST. LESSER CONFIDENCE. THERE ARE STILL CONCERNS OF FASTER WINDS ALOFT BEING DRAGGED DOWN TO THE SURFACE. THERE HAVE BEEN SEVERAL OBSERVATIONS ALREADY OF WINDS GUSTING 40 TO 50 MPH. WILL BE CLOSELY MONITORING TOWARDS THE ISSUANCE OF SPECIAL WEATHER STATEMENTS AND MARINE WARNINGS. GALE WARNINGS CONTINUE ACROSS A MAJORITY OF THE WATERS. MUCH OF THE RAIN AND ASSOCIATED GUSTY WINDS SHOULD BE ALONG THE EAST SHORELINE AND OFFSHORE TOWARDS MORNING ALONG AND AHEAD OF THE ATTENDANT COLD FRONT PRESENTLY /AS OF 2 AM/ ENTERING THE CONNECTICUT RIVER VALLEY. NEAR-TERM MESOSCALE GUIDANCE HAS BEEN DOING FAIRLY WELL IN HANDLING OUTCOMES...MOST ESPECIALLY A BLEND OF THE WRF AND RAP FORECAST GUIDANCE. && .SHORT TERM /6 AM THIS MORNING THROUGH 6 PM SUNDAY/... SATURDAY INTO SATURDAY NIGHT... COLD FRONT WILL EXIT THE REGION BY THE MID-MORNING HOURS. EXPECT CONDITIONS TO LINGER ON ACK A LITTLE LONGER. OTHERWISE DRY AIR WILL PUSH THROUGH BEHIND THE FRONT BRINGING IN SOME CAA. TEMPS TOMORROW WILL BE ALMOST 10-15 DEGREES COOLER THEN TODAY WITH HIGHS IN THE UPPER 50S TO LOW 60S. NW WINDS WILL INCREASE TOMORROW...GUSTING TO 20-25 MPH. LOWS OVERNIGHT WILL DROP BACK BELOW THE FREEZING MARK EXCEPT FOR AREAS ALONG THE COASTLINE. HIGH PRESSURE WILL SLOWLY TRY TO BUILD ALLOWING FOR CLEARING SKIES AND LIGHT WINDS...PERFECT FOR RADIATIONAL COOLING. && .LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/... BIG PICTURE... UPPER RIDGE SHIFTS OVER THE WESTERN ATLANTIC. SECOND UPPER RIDGE TAKES UP POSITION OFF THE PACIFIC COAST. THIS MAKES ROOM FOR A BROAD TROUGH TO DIG OVER THE INTERIOR USA. SHORTWAVE IN THIS BROAD FLOW MOVES FROM THE PACIFIC NORTHWEST TO THE SOUTHERN USA OVER THE WEEKEND...THEN GENERATES A INVERTED TROUGH AT THE SURFACE OFF THE CAROLINA COAST. THE FULL COMPLEX MOVES PAST NEW ENGLAND WEDNESDAY. ANOTHER BETTER DEFINED SHORTWAVE DIVES SOUTH FROM NORTHERN CANADA INTO THE INTERIOR USA TROUGH AND THEN SWINGS ACROSS NEW ENGLAND LATE WEEK. UPPER JET OVER NEW ENGLAND MOVES NORTHEAST PAST GREENLAND/ICELAND. ANOTHER JET SEGMENT TRACES THE PACIFIC NORTHWEST/SOUTHERN ROCKIES...THIS EVENTUALLY SWINGS NORTHEAST THROUGH THE GREAT LAKES MIDWEEK AND THE NORTHEAST USA LATE WEEK. MODEL PREFERENCES... SMALL DIFFERENCE IN GFS AND ECMWF UPPER CONTOUR FIELDS REGARDING COASTAL SYSTEM NEXT WEEK. OTHERWISE THE LONG RANGE MODELS ARE IN GOOD AGREEMENT SURFACE AND ALOFT. WE USED A BLEND OF GFS/ECMWF VALUES...AND BLEND WITH GMOS/HPC GRIDS WHERE AVAILABLE. THE DAILIES... SUNDAY-MONDAY... HIGH PRESSURE BUILDS OVER THE REGION SUNDAY AND THEN MOVES OFFSHORE MONDAY. GENERALLY FAIR WEATHER WITH INCREASING CIRRUS DURING MONDAY. AS WIND FIELDS LIGHTEN SUNDAY AFTERNOON THERE WILL BE THE POTENTIAL FOR A SEA BREEZE. THE OVERALL GRADIENT FLOW THEN SUPPORTS AN EAST FLOW ON MONDAY. TEMPS IN THE MIXED LAYER WILL BE -3C TO -5C SUNDAY WHICH WOULD SUPPORT 50S AT THE SURFACE. CLEAR SKIES AND LIGHT WINDS WILL ALLOW RADIATIONAL COOLING SUNDAY NIGHT...WITH DEWPOINTS IN THE 20S THAT SHOULD ALLOW FOR MIN TEMPS IN THE 20S AND LOWER 30S EXCEPT A LITTLE MILDER ALONG THE COAST. TEMPS ALOFT WARM A LITTLE ON MONDAY...BUT THE BUFFERING OF THE INCREASED EAST FLOW SHOULD BALANCE OFF ANY WARMING. MONDAY NIGHT-TUESDAY... INVERTED TROUGH/DEVELOPING COASTAL LOW WILL START PUSHING DEEPER MOISTURE UP THE COAST. ALL MODEL PCPN FORECASTS ARE WELL SOUTH OF NEW ENGLAND MONDAY EVENING BUT MOVE MEASURABLE PCPN INTO THE AREA...ESPECIALLY THE SOUTH COAST...AFTER 06Z/2AM. WE SLOWED THE HOURLY POP VALUES A FEW HOURS BASED ON THIS MODEL AGREEMENT. NEW ENGLAND IS IN THE RIGHT ENTRANCE REGION OF THE DEPARTING UPPER JET THROUGH TUESDAY SO DEVELOPMENT AND PCPN ARE REASONABLE. CHANCE POPS UNTIL THE SURFACE LOW/UPPER SHORTWAVE MOVE PAST ON TUESDAY NIGHT. WEDNESDAY-THURSDAY... PLAINS/GREAT LAKES TROUGH AND SUPPORTING UPPER JET MOVE UP THE ST LAWRENCE VALLEY INTO CANADA. THIS FEATURE WILL SUPPORT A COLD FRONT THAT WILL SWING THROUGH NEW ENGLAND WEDNESDAY NIGHT- THURSDAY. ON WEDNESDAY POPS SHOW A BREAK AFTER THE COASTAL SYSTEM MOVES OFF...BUT THEN A RESUMPTION OF CHANCE POPS AS THE GREAT LAKES COLD FRONT MOVES THROUGH. THE DEPICTION OF TWO DISTINCT SYSTEMS IS REASONABLE GIVEN THAT ONE IS SOUTHERN STREAM AND THE OTHER IS NORTHERN STREAM...BUT THE DISTINCTNESS/LENGTH OF TIME BETWEEN THE TWO PCPN SHIELDS IS LESS CERTAIN. FRIDAY... HIGH PRESSURE BUILDS AT THE SURFACE WHILE THE SUPPORTING UPPER TROUGH FROM THURSDAY/S FRONT WILL STILL BE IN THE NEIGHBORHOOD. NO DESTABILIZING EXPECTED AS UPPER TEMPS SHOW LITTLE CHANGE AND MOISTURE IS LIMITED. EXPECT A DRY DAY WITH SIMILAR MAX/MIN TEMPS. && .AVIATION /06Z SATURDAY THROUGH WEDNESDAY/... FORECASTER CONFIDENCE LEVELS... LOW...LESS THAN 30 PERCENT. MODERATE...30 TO 60 PERCENT. HIGH...GREATER THAN 60 PERCENT. OVERVIEW... * MODERATE CONFIDENCE INTO SATURDAY MORNING... * HIGH CONFIDENCE SATURDAY AFTERNOON INTO SUNDAY... A MIX OF MVFR-IFR CIGS AND VSBYS CONTINUE WITH THE BROAD AREA OF RAIN WITH EMBEDDED HEAVIER SHOWERS. ALREADY BEGINNING TO SEE WINDS BACKING OUT OF THE WEST-NORTHWEST WITH THE COLD FRONTAL PASSAGE INTO THE CONNECTICUT RIVER VALLEY...THOUGH CIGS ARE SLOW TO LIFT. WHILE DIFFICULTIES PERSIST IN TIMING OF IMPROVEMENT WEST TO EAST...HAVE CONFIDENCE CONCERNING THE OVERALL TREND THAT VSBYS WILL QUICKLY IMPROVE BEHIND THE COLD FRONT AND CIGS WILL GRADUALLY LIFT. WINDS WILL BACK OUT OF THE WEST-NORTHWEST WITH GUSTS UP TO 25 KTS WITH SCT-BKN DIURNAL CU DURING TODAY. IMPROVING TO VFR. INTO THE EVENING AND ON INTO SUNDAY...WINDS SHOULD BECOME LIGHT AND VARIABLE. SEA-BREEZE LIKELY TO IMPACT COASTAL TERMINALS. WILL NEED TO MONITOR CLOSELY FOR THE DEVELOPMENT OF FOG OVERNIGHT IN LOW LYING LOCATIONS AS MUCH COLDER AIR SETTLES INTO THE REGION. MOSTLY CLEAR CONDITIONS. VFR. KBOS TERMINAL...MODERATE CONFIDENCE. WHILE FAIRLY CERTAIN ON TRENDS...THE TIMING OF IMPACTS OVER THE NEXT SEVERAL HOURS COUPLED WITH IMPROVEMENT REMAINS CHALLENGING. COULD SEE SEA-BREEZE IMPACTS ON SUNDAY. KBDL TERMINAL...MODERATE CONFIDENCE. GRADUAL IMPROVEMENT SHOULD BEGIN AS THE COLD FRONT HAS SWEPT ACROSS THE TERMINAL...THE TIMING OF WHICH REMAINS TRICKY. COULD SEE SOME FOG IMPACTS SATURDAY NIGHT INTO SUNDAY MORNING. OUTLOOK...SUNDAY THROUGH WEDNESDAY... SUNDAY NIGHT-MONDAY...VFR. LIGHT WINDS SUNDAY NIGHT. INCREASING EAST WINDS MONDAY WITH GUSTS TO 25 KNOTS ALONG THE CAPE AND ISLANDS/SOUTH COAST. HIGH CONFIDENCE. MONDAY NIGHT-TUESDAY...CONDITIONS LOWERING LATER MONDAY NIGHT WITH MVFR/IFR CIGS/VSBY POSSIBLE TUESDAY ESPECIALLY RI AND SOUTHEAST MASS. MODERATE CONFIDENCE. WEDNESDAY...CONDITIONS IMPROVING TO VFR DURING THE MORNING AND AFTERNOON AS TUESDAY/S STORM MOVES OFF. A COLD FRONT APPROACHES LATE IN THE DAY...BUT EFFECTS MAY HOLD OFF UNTIL WEDNESDAY NIGHT WHEN CONDITIONS MAY LOWER TO MVFR/IFR IN SHOWERS/SCATTERED TSTMS. LOW TO MODERATE CONFIDENCE. && .MARINE... FORECASTER CONFIDENCE LEVELS... LOW...LESS THAN 30 PERCENT. MODERATE...30 TO 60 PERCENT. HIGH...GREATER THAN 60 PERCENT. OVERVIEW...MODERATE CONFIDENCE THROUGH SUNDAY. QUICK UPDATE TO NARRANGANSETT BAY...NOW UNDER A GALE WARNING. WIND GUSTS HAVE BEEN APPROACHING GALE FORCE ALREADY AND EXPECTATIONS ARE FOR SEVERAL MORE HOURS OF GUSTS THIS STRONG OR EVEN STRONGER AS CONVECTION APPROACHES. STRONG SOUTHERLY WINDS WITH GUSTS TO 25KTS. AS A STRONG COLD FRONT APPROACHES GUSTS WILL INCREASE TO STRONG SCA TO MARGINAL GALES. DECIDED TO HOIST THE GALE WARNING UP DUE TO COLD FRONT PASSAGE ALLOWING FOR STRONGER WINDS ALOFT TO MIX DOWN. THESE GALES MAY REACH TO 40KTS. SHOWERS AND THUNDERSTORMS EXPECTED OVERNIGHT INTO EARLY SAT MORNING WILL LIKELY RESULT IN SOME TEMPORARY VISIBILITY RESTRICTIONS. BEHIND THE COLD FRONT...WINDS WILL BACK OUT OF THE WEST-NORTHWEST CONTINUALLY GUSTING IN EXCESS OF 25 KTS. SMALL CRAFT ADVISORIES WILL NEED TO BE ISSUED ACCORDINGLY. AS SEAS WILL STILL REMAIN CHOPPY AND GREATER THAN 5 FEET. HIGH PRESSURE WILL BUILD SATURDAY NIGHT ALLOWING FOR CALM WINDS AND SEAS TO SLOWLY RELAX. OUTLOOK...SUNDAY THROUGH WEDNESDAY... MODERATE CONFIDENCE SUNDAY TO TUESDAY. LOW TO MODERATE CONFIDENCE WEDNESDAY. SUNDAY...DIMINISHING WIND. LINGERING 5 FOOT SEAS EARLY ON THE OUTER WATERS...SUBSIDING. MONDAY...INCREASING EAST WIND WITH POTENTIAL SMALL CRAFT WIND GUSTS TO 25 KNOTS AND SEAS 5 FEET OR HIGHER IN THE AFTERNOON AND AT NIGHT ESPECIALLY ON THE SOUTHERN WATERS. TUESDAY...SEAS AT OR ABOVE 5 FEET ON THE OPEN WATERS. EAST WINDS GUSTING AROUND 25 KNOTS. SMALL CRAFT ADVISORY LIKELY. SHOWERS. WEDNESDAY...A SHORT BREAK BETWEEN WEATHER SYSTEMS. WINDS GENERALLY BELOW 25 KNOTS...BUT MAY INCREASE TO NEAR 25 KNOTS ON THE EASTERN WATERS LATE IN THE DAY. SEAS 5-6 FEET MAINLY ON THE OUTER WATERS. && .BOX WATCHES/WARNINGS/ADVISORIES... CT...NONE. MA...NONE. NH...NONE. RI...NONE. MARINE...GALE WARNING UNTIL 6 AM EDT EARLY THIS MORNING FOR ANZ231>234- 250-251-256. SMALL CRAFT ADVISORY UNTIL 8 AM EDT THIS MORNING FOR ANZ230. GALE WARNING UNTIL 3 AM EDT EARLY THIS MORNING FOR ANZ235>237. GALE WARNING UNTIL 8 AM EDT THIS MORNING FOR ANZ254-255. && $$ SYNOPSIS...WTB/DUNTEN NEAR TERM...SIPPRELL SHORT TERM...DUNTEN LONG TERM...WTB AVIATION...WTB/BELK/SIPPRELL MARINE...WTB/DUNTEN
AREA FORECAST DISCUSSION
NWS MIAMI FL
125 AM EDT SAT APR 20 2013 .AVIATION... MOSTLY VFR IS EXPECTED THROUGH THE FORECAST BUT BRIEF MVFR CIGS MAY OCCUR EARLY AS SCATTERED SHOWERS MOVE TO THE NORTH OVER THE ATLANTIC AND A FEW MOVE ONSHORE NEAR THE EAST COAST TERMINALS. MOISTURE AND INSTABILITY WILL BE ON THE INCREASE THROUGH THE DAY SO SOME CONVECTION IS EXPECTED AFT 18Z WITH STEERING MOTION TAKING THE CELLS TOWARDS THE EAST COAST. SURFACE WIND WILL GENERALLY BE SSE WITH A GULF SEA BREEZE AFT 16Z. COLD FRONT WILL SAG SOUTHWARD AND MAY MOVE FAR ENOUGH SOUTH TO ALLOW SURFACE FLOW AT KPBI TO BECOME NE LATE IN THE DAY. KOB && .PREV DISCUSSION... /ISSUED 814 PM EDT FRI APR 19 2013/ AVIATION... OVERNIGHT SHOWERS WILL REMAIN POSSIBLE AS A COLD FRONT APPROACHES THE LOCAL AREA TONIGHT INTO SATURDAY. ALTHOUGH THERE REMAINS SOME UNCERTAINTY REGARDING THE OVERNIGHT COVERAGE DUE MODEL DIFFERENCES BETWEEN THE HRRR AND WRF GUIDANCE...WE WILL KEEP LATE NIGHT/EARLY MORNING VCSH IN THIS PACKAGE ALONG THE EAST COAST AND UPGRADE AS NECESSARY. BRIEF PERIODS WITH MVFR CIGS/VSBYS CAN`T BE RULED OUT AS THESE SHOWERS DEVELOP AND SPREAD ASHORE THROUGH THIS TIME. LATER TOMORROW...WINDS WILL BEGIN TO SHIFT TO THE NNW TO NNE AT APF AND POSSIBLY PBI THROUGH THE AFTERNOON PERIOD AS THE FRONT MAKES ITS WAY INTO THE AREA. FARTHER SOUTH ALONG THE EAST COAST ALONG AND AHEAD OF THE BOUNDARY...TEMPOS FOR POTENTIAL TSTMS HAVE BEEN INCLUDED. PREV DISCUSSION... /ISSUED 655 PM EDT FRI APR 19 2013/ UPDATE... THERE HAS BEEN JUST ONE LONE CLOUD TO GROUND LIGHTNING STRIKE THIS AFTERNOON...AND IT OCCURRED OVER THE PAST HOUR. HIGH RES MODELS INDICATE THAT THE ACTIVITY OVER INLAND COLLIER...HENDRY AND GLADES COUNTIES WILL TAPER OFF A FEW HOURS AFTER SUNSET. ISOLATED TO SCATTERED SHOWERS ARE EXPECTED OVER THE ATLANTIC WATERS...AND THESE SHOWERS WILL MAKE THEIR WAY TOWARDS THE EAST COAST. SO LEFT THE CHANCE OF SHOWERS FOR THE EAST COAST...AND LOWERED POPS FOR THE REST OF THE REGION. A COLD FRONT IS EXPECTED TO STALL OVER SOUTH CENTRAL FLORIDA LATE TONIGHT INTO THE DAY ON SATURDAY...WITH INCREASING RAIN CHANCES FOR SOUTH FLORIDA THIS WEEKEND. LOCALLY HEAVY RAINFALL...GUSTY WINDS...AND FREQUENT CLOUD TO GROUND LIGHTNING ARE THE MAIN THREATS ON SATURDAY...WITH THE BEST CHANCE OF STORMS FOR THE EASTERN HALF OF THE REGION. STRONG STORMS MAY BE POSSIBLE ON SUNDAY AS TEMPERATURES ALOFT COOL...WITH HAIL...LOCALLY HEAVY RAINFALL...AND STRONG GUSTY WINDS THE MAIN THREATS. PREV DISCUSSION... /ISSUED 338 PM EDT FRI APR 19 2013/ UPDATE... QUICK UPDATE TO ADD A HIGH RISK OF RIP CURRENTS AT THE EAST COAST BEACHES. OBSERVATIONS SHOW SOUTHEAST WINDS AROUND 20 MPH...AND MIAMI BEACH OCEAN RESCUE REPORTED RESCUES DUE TO RIP CURRENTS THIS AFTERNOON. THE HIGH RISK OF RIPS IS IN EFFECT UNTIL 9 PM THIS EVENING. WINDS ARE FORECAST TO BE MORE PARALLEL TO THE COAST AND WEAKER ON SATURDAY AHEAD OF THE WEAKENING FRONTAL BOUNDARY. PREV DISCUSSION... /ISSUED 239 PM EDT FRI APR 19 2013/ DISCUSSION... DEEPER MOISTURE CONTINUES TO SPREAD ACROSS THE SOUTH FLORIDA PENINSULA THIS AFTERNOON AHEAD OF AN APPROACHING COLD FRONT. THIS HAS ALLOWED SCATTERED SHOWERS TO CONTINUE TO DOT THE AREA EARLY THIS AFTERNOON MAINLY ACROSS THE INTERIOR WHERE TEMPERATURES ARE CURRENTLY RUNNING SEVERAL DEGREES WARMER THAN COASTAL AREAS. LATEST GUIDANCE KEEPS THESE SHOWERS ACROSS NORTHERN INTERIOR AREAS THROUGH THE REMAINDER OF THE AFTERNOON AND INTO THE EARLY EVENING. THE COLD FRONT IS STILL EXPECTED TO PUSH INTO THE SOUTH FLORIDA AREA SATURDAY MORNING AND STALL AROUND THE LAKE OKEECHOBEE REGION. THE STALLED BOUNDARY COMBINED WITH DECENT INSTABILITY...LIFTED INDICES -2C TO -4C ALONG WITH SBCAPE VALUES AROUND 1400 J/KG...WILL RESULT IN SHOWERS AND THUNDERSTORMS AREA WIDE SATURDAY AFTERNOON. COULD NOT RULE OUT A FEW STRONG STORMS BUT BELIEVE MID LEVEL RIDGING WILL STAY FAIRLY STRONG THROUGH THE PEAK HEATING HOURS WHICH SHOULD INHIBIT WIDESPREAD STRONG TO SEVERE THUNDERSTORMS. BY SUNDAY HOWEVER UPPER RIDGING BEGINS TO BREAK DOWN ACROSS THE AREA AS A LONGWAVE TROUGH BEGINS TO SWEEP THROUGH THE DEEP SOUTH. THIS WILL ALLOW FOR BETTER COOLING ALOFT. MODEL SOUNDINGS SUNDAY DEPICT 500 MB TEMPERATURES AROUND -12C...DOWN FROM -8C ON SATURDAY. THIS COMBINED WITH THE STALLED FRONT LINGERING ACROSS THE AREA WILL ENHANCE SHOWER AND THUNDERSTORM DEVELOPMENT ACROSS THE AREA. A FEW STORMS COULD BE STRONG AND COULD NOT RULE OUT AN ISOLATED SEVERE STORM WITH GUSTY WINDS...HAIL...AND HEAVY DOWNPOURS BEING THE MAIN IMPACTS. SHOWERS AND POSSIBLY A FEW THUNDERSTORMS SHOULD LINGER THROUGH THE EVENING AND INTO THE OVERNIGHT HOURS AS A FEW MID LEVEL DISTURBANCES SWING THROUGH THE AREA. MODELS DO INDICATE A REMNANT TROUGH FROM THE STALLED FRONT LINGERING AROUND THE AREA THROUGH MONDAY WHICH WILL KEEP CHANCES FOR SHOWERS AND THUNDERSTORMS THROUGH MONDAY. THERMODYNAMICS SHOULD BE SIMILAR MONDAY AFTERNOON AS OVER THE WEEKEND...SO CAN/T RULE OUT A FEW STRONG STORMS AGAIN DURING PEAK HEATING HOURS. A PREVAILING EASTERLY FLOW WILL RETURN TUESDAY THROUGH WEDNESDAY WITH SLIGHT CHANCES OF SEA BREEZE INDUCED SHOWERS AND THUNDERSTORMS EACH DAY. A WEAK COLD FRONT WILL PUSH INTO THE AREA THURSDAY BUT SHOULD DO LITTLE MORE THAN DECREASE TEMPERATURES A FEW DEGREES. MARINE... WINDS AND SEAS MAINLY EXPECTED TO BE BELOW ADVISORY LEVELS THROUGH THE PERIOD. WINDS AND SEAS COULD BE LOCALLY HIGHER IN OR NEAR ANY THUNDERSTORMS THAT DEVELOP OVER THE WEEKEND. FIRE WEATHER... MINIMUM RELATIVE HUMIDITY VALUES SHOULD STAY ABOVE CRITICAL THRESHOLDS THROUGH THE PERIOD WITH PLENTY OF LOW LEVEL MOISTURE IN PLACE. A FEW STRONG STORMS WILL BE POSSIBLE BOTH SATURDAY AND SUNDAY AS A COLD FRONT STALLS ACROSS THE AREA. && .MFL WATCHES/WARNINGS/ADVISORIES... FL...NONE. AM...NONE. GM...NONE. && $$
AREA FORECAST DISCUSSION
NWS MELBOURNE FL
9 PM EDT FRI APR 19 2013 .DISCUSSION... ...STRONG STORMS AND HEAVY RAINFALL THIS EVENING... CURRENT...A COLD FRONT WAS MOVING ACROSS THE NORTHEAST GULF OF MEXICO AND THE FLORIDA BIG BEND REGIONS. AREAS OF SHOWERS WITH AN EMBEDDED LIGHTNING STORM OR TWO WERE MOVING TO THE NORTHEAST AT 15 MPH ACROSS THE EASTERN GULF OF MEXICO. SHOWERS EMBEDDED IN THE SOUTHWEST FLOW AHEAD OF THE FRONT WERE MOVING TO THE NORTHEAST AT 15 MPH ACROSS CENTRAL FLORIDA AND INTO THE COASTAL WATERS. MANY OF THE SHOWERS CONTAINED WIND GUSTS TO 35 MPH. OVERNIGHT...THE LATEST RUC RUN WAS INDICATING THAT A STRONG VORT MAX OVER THE NORTHEAST GULF WILL MOVE ACROSS CENTRAL FLORIA OVERNIGHT AND WILL HELP TO TRIGGER MORE SHOWERS BEFORE EXITING TO THE NORTHEAST SATURDAY MORNING. LIKELY POP NORTH TO CHANCE POP SOUTH STILL LOOKS GOOD FOR THE OVERNIGHT. CONTINUED SOUTH TO SOUTHWEST WIND OVERNIGHT WILL KEEP LOWS IN THE MID TO UPPER 60S NORTH BREVARD OSCEOLA NORTH AND LOW 70S SOUTH BREVARD OKEECHOBEE SOUTH. PREVIOUS ZONES DISCUSSION TONIGHT...FRONTAL BOUNDARY WILL PUSH INTO NORTHEAST FLORIDA THIS EVENING. THE ASSOCIATED MOISTENING AND LOW LEVEL CONVERGENCE COMBINED WITH MESOSCALE BOUNDARIES MAY SET THE STAGE FOR SOME STRONG STORMS AND HEAVY RAINFALL. THE GFS HAS INDICATED THE PAST FEW RUNS THAT THE HIGHEST QPF WOULD BE FROM BREVARD NORTHEAST OVER THE ATLANTIC. INTERESTINGLY...THE 12Z NAM CRANKED OUT COPIOUS PRECIP OVER BREVARD COUNTY. AS ALL THE BOUNDARIES COME TOGETHER...LIKELY POPS SEEM IN ORDER FOR MUCH OF NORTHERN HALF. WILL HAVE TO WATCH FOR STRONG TO MARGINALLY SEVERE STORMS THROUGH EVENING AND ALSO FOR A POTENTIAL OF TRAINING CELLS AND HEAVY RAINFALL AS THE FRONTAL BOUNDARY SLIDES SLOWLY INTO CENTRAL FLORIDA. SAT...THE FRONTAL BOUNDARY WILL CONTINUE A SLOW TREK THROUGH OUR AREA AND SHOULD SETTLE INTO SOUTH FLORIDA LATE. EXPECT A LOT OF MOISTURE AHEAD OF AND BEHIND THE FRONT. THEREFORE THE LIKELY MOS POPS LOOK REASONABLE. SOME HEAVY RAINFALL MAY OCCUR NEAR THE BOUNDARY...ESPECIALLY OVER THE COASTAL WATERS. CLOUDS AND PRECIP WILL LIMIT MAX TEMPS. MOST SPOTS WILL STAY IN THE 70S...THOUGH SOUTHERN AREAS MAY REMAIN PRE FRONTAL LONG ENOUGH TO REACH THE MID 80S...AND THE NORTH COAST MAY STRUGGLE TO REACH 70 DEGREES. SATURDAY NIGHT - SUNDAY NIGHT A PERIOD OF MOSTLY CLOUDY SKIES AND HIGHER THAN NORMAL PRECIPITATION CHANCES IS EXPECTED THROUGH SUNDAY NIGHT AS A FRONTAL BOUNDARY WASHES OUT OVER THE REGION. LOCALLY...WINDS WILL CLOCK AROUND TO THE NORTH AND EAST AND INCREASE SATURDAY NIGHT...ESPECIALLY UP NORTH. WHILE PRECIPITABLE WATERS REMAIN HIGH IN THE VICINITY OF THE FRONT...LITTLE IN THE WAY OF UPPER LEVEL DYNAMICS SHOULD KEEP US IN A MORE SHOWERY REGIME. OVERALL...BEST RAIN CHANCES SEEM TO BE FURTHER SOUTH WHERE HIGHER MOISTURE POOLING IS ANTICIPATED. CLOUD COVER SHOULD REMAIN HIGH THROUGH THE PERIOD...LEADING TO SLIGHTLY LOWER MAX TEMPERATURES DURING THE DAY. AREAS NORTH OF THE FRONTAL BOUNDARY SHOULD SEE A TEMPERATURE DROP...AT LEAST INITIALLY BEHIND THE FRONT. TEMPS NEAR 60 ARE ADVERTISED FOR SATURDAY NIGHT ACROSS OUR NORTHERN COUNTIES...BUT EVEN THOSE WILL BE SHORT LIVED AS NORTHEAST WINDS QUICKLY MODIFY TEMPERATURES BEHIND THE BOUNDARY. MON-THU... UNSETTLED WX APPEARS IN THE MAKING AS THE FRONTAL TROF GRADUALLY WASHES OUT OVER CENTRAL FL. LINGERING MOISTURE WITHIN THE TROF WILL MAINTAIN CHC POPS AREAWIDE INTO MON...SLGT CHC FOR THE SPACE/TREASURE COASTS INTO TUE. BOTH GFS/ECMWF MODELS DVLP A WEAK SPOT LOW OFF THE CAROLINA COAST ALONG THE DISSIPATING BOUNDARY LATE MON INTO TUE WHICH WOULD HELP PUSH DRIER CONTINENTAL AIR INTO CENTRAL FL TUE-TUE NIGHT. HOWEVER...BOTH MODELS ALSO BRING A NEW COLD FRONT INTO FL LATE WED INTO THU. GIVEN THE EXTENDED PRESENCE OF THE OLD FRONT...IT APPEARS UNLIKELY THAT THE LCL AIRMASS WILL DRY OUT ENOUGH TO KEEP POPS OUT OF THE FCST COMPLETELY THRU MIDWEEK. NOTHING TO INDICATE UNUSUALLY HIGH OR LOW TEMPS THRU MIDWEEK... READINGS SHOULD BE WITHIN ABOUT 5F DEG OF CLIMO AVGS. && .AVIATION... TEMPO MVFR VICINITY AND IN SHOWERS OVERNIGHT. SOUTH TO SOUTHWEST WINDS TO 10 KNOTS THEN SHIFT TO THE WEST AND NORTHWEST 08Z TO 12Z AS THE FRONT MOVES ACROSS CENTRAL FLORIDA. MVFR CEILINGS IN THE NORTH TO NORTHEAST FLOW AFTER 18Z. && .MARINE... BUOYS RECORDING SOUTHERLY WINDS 15 TO 20 KNOTS AND 5 FOOT SEAS. WINDS SHIFT TO THE SOUTHWEST BUT REMAIN THE SAME SPEEDS LATE OVERNIGHT AS THE FRONT NEARS CENTRAL FLORIDA. PREVIOUS MARINE DISCUSSION TONIGHT-SAT...BREEZY PRE FRONTAL SOUTHERLY WINDS WILL NECESSITATE EXERCISE CAUTION HEADLINES TONIGHT...ESPECIALLY FOR THE OFFSHORE ZONES. WINDS AT SIMILAR SPEEDS BEHIND THE FRONT LATE TONIGHT AND INTO SAT WILL LIKELY CAUSE THESE EXERCISE CAUTION CONDITIONS TO CONTINUE. AN INCREASE IN SHOWERS/STORMS WILL ALSO OCCUR THIS EVENING AND SOME STRONG STORMS SHOULD MOVE ACROSS THE COAST. MARINERS CAN ALSO EXPECT A BAND OF SHOWERS AND ISOLATED STORMS TO ACCOMPANY THE FRONTAL PASSAGE...SO IN ADDITION TO MARGINALLY HAZARDOUS WINDS/SEAS...THE WEATHER WILL ALSO BECOME RATHER ADVERSE FOR MARINERS. SUN...NORTHEAST WINDS BEHIND FRONT SHOULD CONTINUE POOR BOATING CONDITIONS ESPECIALLY OVER THE NORTHERN WATERS. GREATEST CONCENTRATION OF RAINFALL SHOULD BE IN THE SOUTH NEAR THE STALLED FRONTAL BOUNDARY. MON-WED...THE FRONTAL BOUNDARY SHOULD GRADUALLY WASH OUT ACROSS CENTRAL/SOUTH FLORIDA. BREEZY NORTHEAST FLOW WILL PERSIST TO THE NORTH OF THE BOUNDARY...PRIMARILY THE NORTHERN WATERS INTO TUE. && .MLB WATCHES/WARNINGS/ADVISORIES... FL...NONE. AM...NONE. && $$ UPDATES/AVIATION...WIMMER RADAR/IMPACT WX....CRISTALDI
AREA FORECAST DISCUSSION
NWS MIAMI FL
814 PM EDT FRI APR 19 2013 .AVIATION... OVERNIGHT SHOWERS WILL REMAIN POSSIBLE AS A COLD FRONT APPROACHES THE LOCAL AREA TONIGHT INTO SATURDAY. ALTHOUGH THERE REMAINS SOME UNCERTAINTY REGARDING THE OVERNIGHT COVERAGE DUE MODEL DIFFERENCES BETWEEN THE HRRR AND WRF GUIDANCE...WE WILL KEEP LATE NIGHT/EARLY MORNING VCSH IN THIS PACKAGE ALONG THE EAST COAST AND UPGRADE AS NECESSARY. BRIEF PERIODS WITH MVFR CIGS/VSBYS CAN`T BE RULED OUT AS THESE SHOWERS DEVELOP AND SPREAD ASHORE THROUGH THIS TIME. LATER TOMORROW...WINDS WILL BEGIN TO SHIFT TO THE NNW TO NNE AT APF AND POSSIBLY PBI THROUGH THE AFTERNOON PERIOD AS THE FRONT MAKES ITS WAY INTO THE AREA. FARTHER SOUTH ALONG THE EAST COAST ALONG AND AHEAD OF THE BOUNDARY...TEMPOS FOR POTENTIAL TSTMS HAVE BEEN INCLUDED. && .PREV DISCUSSION... /ISSUED 655 PM EDT FRI APR 19 2013/ UPDATE... THERE HAS BEEN JUST ONE LONE CLOUD TO GROUND LIGHTNING STRIKE THIS AFTERNOON...AND IT OCCURRED OVER THE PAST HOUR. HIGH RES MODELS INDICATE THAT THE ACTIVITY OVER INLAND COLLIER...HENDRY AND GLADES COUNTIES WILL TAPER OFF A FEW HOURS AFTER SUNSET. ISOLATED TO SCATTERED SHOWERS ARE EXPECTED OVER THE ATLANTIC WATERS...AND THESE SHOWERS WILL MAKE THEIR WAY TOWARDS THE EAST COAST. SO LEFT THE CHANCE OF SHOWERS FOR THE EAST COAST...AND LOWERED POPS FOR THE REST OF THE REGION. A COLD FRONT IS EXPECTED TO STALL OVER SOUTH CENTRAL FLORIDA LATE TONIGHT INTO THE DAY ON SATURDAY...WITH INCREASING RAIN CHANCES FOR SOUTH FLORIDA THIS WEEKEND. LOCALLY HEAVY RAINFALL...GUSTY WINDS...AND FREQUENT CLOUD TO GROUND LIGHTNING ARE THE MAIN THREATS ON SATURDAY...WITH THE BEST CHANCE OF STORMS FOR THE EASTERN HALF OF THE REGION. STRONG STORMS MAY BE POSSIBLE ON SUNDAY AS TEMPERATURES ALOFT COOL...WITH HAIL...LOCALLY HEAVY RAINFALL...AND STRONG GUSTY WINDS THE MAIN THREATS. PREV DISCUSSION... /ISSUED 338 PM EDT FRI APR 19 2013/ UPDATE... QUICK UPDATE TO ADD A HIGH RISK OF RIP CURRENTS AT THE EAST COAST BEACHES. OBSERVATIONS SHOW SOUTHEAST WINDS AROUND 20 MPH...AND MIAMI BEACH OCEAN RESCUE REPORTED RESCUES DUE TO RIP CURRENTS THIS AFTERNOON. THE HIGH RISK OF RIPS IS IN EFFECT UNTIL 9 PM THIS EVENING. WINDS ARE FORECAST TO BE MORE PARALLEL TO THE COAST AND WEAKER ON SATURDAY AHEAD OF THE WEAKENING FRONTAL BOUNDARY. PREV DISCUSSION... /ISSUED 239 PM EDT FRI APR 19 2013/ DISCUSSION... DEEPER MOISTURE CONTINUES TO SPREAD ACROSS THE SOUTH FLORIDA PENINSULA THIS AFTERNOON AHEAD OF AN APPROACHING COLD FRONT. THIS HAS ALLOWED SCATTERED SHOWERS TO CONTINUE TO DOT THE AREA EARLY THIS AFTERNOON MAINLY ACROSS THE INTERIOR WHERE TEMPERATURES ARE CURRENTLY RUNNING SEVERAL DEGREES WARMER THAN COASTAL AREAS. LATEST GUIDANCE KEEPS THESE SHOWERS ACROSS NORTHERN INTERIOR AREAS THROUGH THE REMAINDER OF THE AFTERNOON AND INTO THE EARLY EVENING. THE COLD FRONT IS STILL EXPECTED TO PUSH INTO THE SOUTH FLORIDA AREA SATURDAY MORNING AND STALL AROUND THE LAKE OKEECHOBEE REGION. THE STALLED BOUNDARY COMBINED WITH DECENT INSTABILITY...LIFTED INDICES -2C TO -4C ALONG WITH SBCAPE VALUES AROUND 1400 J/KG...WILL RESULT IN SHOWERS AND THUNDERSTORMS AREA WIDE SATURDAY AFTERNOON. COULD NOT RULE OUT A FEW STRONG STORMS BUT BELIEVE MID LEVEL RIDGING WILL STAY FAIRLY STRONG THROUGH THE PEAK HEATING HOURS WHICH SHOULD INHIBIT WIDESPREAD STRONG TO SEVERE THUNDERSTORMS. BY SUNDAY HOWEVER UPPER RIDGING BEGINS TO BREAK DOWN ACROSS THE AREA AS A LONGWAVE TROUGH BEGINS TO SWEEP THROUGH THE DEEP SOUTH. THIS WILL ALLOW FOR BETTER COOLING ALOFT. MODEL SOUNDINGS SUNDAY DEPICT 500 MB TEMPERATURES AROUND -12C...DOWN FROM -8C ON SATURDAY. THIS COMBINED WITH THE STALLED FRONT LINGERING ACROSS THE AREA WILL ENHANCE SHOWER AND THUNDERSTORM DEVELOPMENT ACROSS THE AREA. A FEW STORMS COULD BE STRONG AND COULD NOT RULE OUT AN ISOLATED SEVERE STORM WITH GUSTY WINDS...HAIL...AND HEAVY DOWNPOURS BEING THE MAIN IMPACTS. SHOWERS AND POSSIBLY A FEW THUNDERSTORMS SHOULD LINGER THROUGH THE EVENING AND INTO THE OVERNIGHT HOURS AS A FEW MID LEVEL DISTURBANCES SWING THROUGH THE AREA. MODELS DO INDICATE A REMNANT TROUGH FROM THE STALLED FRONT LINGERING AROUND THE AREA THROUGH MONDAY WHICH WILL KEEP CHANCES FOR SHOWERS AND THUNDERSTORMS THROUGH MONDAY. THERMODYNAMICS SHOULD BE SIMILAR MONDAY AFTERNOON AS OVER THE WEEKEND...SO CAN/T RULE OUT A FEW STRONG STORMS AGAIN DURING PEAK HEATING HOURS. A PREVAILING EASTERLY FLOW WILL RETURN TUESDAY THROUGH WEDNESDAY WITH SLIGHT CHANCES OF SEA BREEZE INDUCED SHOWERS AND THUNDERSTORMS EACH DAY. A WEAK COLD FRONT WILL PUSH INTO THE AREA THURSDAY BUT SHOULD DO LITTLE MORE THAN DECREASE TEMPERATURES A FEW DEGREES. MARINE... WINDS AND SEAS MAINLY EXPECTED TO BE BELOW ADVISORY LEVELS THROUGH THE PERIOD. WINDS AND SEAS COULD BE LOCALLY HIGHER IN OR NEAR ANY THUNDERSTORMS THAT DEVELOP OVER THE WEEKEND. FIRE WEATHER... MINIMUM RELATIVE HUMIDITY VALUES SHOULD STAY ABOVE CRITICAL THRESHOLDS THROUGH THE PERIOD WITH PLENTY OF LOW LEVEL MOISTURE IN PLACE. A FEW STRONG STORMS WILL BE POSSIBLE BOTH SATURDAY AND SUNDAY AS A COLD FRONT STALLS ACROSS THE AREA. && .PRELIMINARY POINT TEMPS/POPS... WEST PALM BEACH 75 83 71 84 / 30 50 40 60 FORT LAUDERDALE 77 86 74 85 / 30 50 30 60 MIAMI 77 87 73 84 / 30 50 30 50 NAPLES 72 87 69 86 / 20 40 30 50 && .MFL WATCHES/WARNINGS/ADVISORIES... FL...HIGH RIP CURRENT RISK UNTIL 9 PM EDT THIS EVENING FOR COASTAL BROWARD-COASTAL MIAMI DADE-COASTAL PALM BEACH. AM...NONE. GM...NONE. && $$ DISCUSSION/MARINE/FIRE...84/AK AVIATION/RADAR...85/AG
AREA FORECAST DISCUSSION...UPDATED
NWS GRAY ME
1102 PM EDT FRI APR 19 2013 .SYNOPSIS... A COLD FRONT WILL CROSS THE AREA TONIGHT. A TROUGH OF LOW PRESSURE REMAINS OVER THE REGION THROUGH SATURDAY. HIGH PRESSURE BUILDS IN SUNDAY THROUGH TUESDAY. WEAK LOW PRESSURE PASSES OFFSHORE ON WEDNESDAY. A COLD FRONT MOVES THROUGH FROM WEST TO EAST LATE WEDNESDAY NIGHT INTO THURSDAY. HIGH PRESSURE RETURNS FOR THE END OF THE WEEK. && .NEAR TERM /THROUGH SATURDAY/... UPDATE...POP LOOKS ON TRACK WITH SQUALL LINE ENTERING WRN CWFA ATTM. HAVE ADDED GUSTY WINDS TO SRN NH...WHERE STRONGLY FORCED LINE OF SHWRS AND EMBEDDED THUNDER COULD SUPPORT A COUPLE GUST TO 40 KT. AS OF THIS WRITING KLEB HAS GUSTED TO 40 KT WITH PASSAGE OF LEADING EDGE OF SHWRS. PREVIOUS DISCUSSION...NO MAJOR CHANGES TO THE CURRENT FCST. CONVECTIVE SHRA WITH EMBEDDED TSTMS ARE ADVANCING INTO THE HUDSON VALLEY ATTM. REMAINING INSTABILITY IS LIMITED TO THE CATSKILLS...AND THIS IS WHERE CURRENT SVR WARNINGS ARE IN EFFECT. THIS INSTABILITY WILL REMAIN ELEVATED ACROSS SRN NH AND EXTREME SWRN ME...SO DON/T EXPECT SVR WX. HOWEVER...MID LVL LAPSE RATES REMAIN ON THE ORDER OF 7 C/KM...SO TSTMS SHOULD BE ABLE TO MAINTAIN THEMSELVES INTO THE REGION. WILL CONTINUE WITH ISOLD THUNDER WORDING IN THE GRIDS. IN ADDITION...STRONG WINDS ALOFT MAY BRIEFLY MIX DOWN WITH FROPA...WITH GUSTY W WINDS TO 40 KT PSBL. HAVE SLOWED FRONTAL PROGRESSION INTO THE CWFA THIS EVE BASED ON LATEST SATELLITE/RADAR TRENDS. REGIONAL MOSAIC INDICATES HRRR HAS A GOOD HANDLE ON CURRENT PLACEMENT SHWRS. THOUGH A PASSING SHRA IS PSBL IN ONSHORE FLOW THIS EVE...BULK OF RNFL WILL HOLD OFF UNTIL AFTER 00Z. HAVE ALSO ADDED ISOLD THUNDER BACK IN FOR SRN NH...AS IT DOES APPEAR ELEVATED INSTABILITY WILL WORK FAR ENOUGH N TO KEEP THE THREAT IN THERE. FOR QPF...BLENDED IN THE LATEST RFC GUIDANCE WITH ECMWF QPF VALUES...WHICH SEEM REPRESENTATIVE FOR A PROGRESSIVE FNT. && .SHORT TERM /SATURDAY NIGHT/... GUSTY CONDITIONS WILL SET UP BEHIND THE FRONT TOMORROW AS COLD AIR ADVECTION GETS GOING. STRONG PRESSURE GRADIENT LOOKS LIKE IT WILL QUICKLY RELAX AS THE DAY PROGRESSES...ALLOWING WINDS TO DROP OFF. HOWEVER...THE AIRMASS BEHIND THE FRONT LOOKS LIKE IT WILL BE VERY DRY. THIS WILL ALLOW TEMPERATURES TOMORROW NIGHT TO DROP QUICKLY AFTER THE WINDS DECOUPLE AND SKIES CLEAR. MOST LOCATIONS WILL SEE TEMPERATURES FALLING TO AROUND OR BELOW FREEZING. && .LONG TERM /SUNDAY THROUGH FRIDAY/... A STRETCH OF DRY WEATHER WILL DEVELOP SUNDAY THROUGH TUESDAY AS STRONG HIGH PRESSURE BUILDS IN FROM THE WEST. HIGH TEMPERATURES WILL WARM INTO THE UPPER 40S NORTH TO MID/UPPER 50S SOUTH WITH FORECASTED HIGHS ARE JUST A COUPLE DEGREES BELOW NORMAL. SUNDAY AND MONDAY IN PARTICULAR LOOK MOSTLY SUNNY. SOUTH WINDS BEGIN TO TRANSPORT MOIST AIR NORTH BY MONDAY NIGHT AS THE CENTER OF THE HIGH BEGINS TO MOVE OFFSHORE. A SOUTHERN STREAM SHORT WAVE MOVING ALONG THE EAST COAST WILL PROMPT A SURFACE LOW TO ORGANIZE SOUTH OF THE GULF OF MAINE. MOST MODELS NOW KEEP MOST OF THE ASSOCIATED PRECIPITATION SOUTH OF MAINE AND NH EVEN THOUGH CLOUDS WILL BE ON THE INCREASE. A FEW LIGHT SHOWERS WILL PROBABLY ENCROACH ON THE COAST TUESDAY NIGHT. AS THE COASTAL SYSTEM MOVES NORTH IT WILL BE ABSORBED IN A LARGER SURFACE LOW TO OUR WEST. THIS IS THE RESULT OF A DEEP LARGE SCALE TROUGH MOVING THROUGH THE CENTRAL AND EASTERN U.S. A SHORT WAVE AXIS WILL BECOME NEGATIVELY TILTED ON THURSDAY AS IT DRIVES A COLD FRONT THROUGH MAINE AND NH. THE EURO REMAINS ABOUT 6 HOURS BEHIND THE GFS WITH THE COLD FRONT AND MAIN BAND OF PRECIPITATION WHICH SHOULD MOVE THROUGH THURSDAY NIGHT. AM LEANING MORE TOWARDS THE EURO SOLUTION BASED ON THE SLOW PERPENDICULAR NATURE OF THE FLOW ALOFT. INSTABILITY LOOKS WEAK WITH THIS EVENT BUT HEAVY RAIN IS LIKELY AT TIMES WITH HIGH MOISTURE CONTENT IN PLACE. WEDNESDAY LOOKS THE WARMEST FOR THE LATTER HALF OF THE WORK WEEK WITH WARM AIR ADVECTION INCREASING AHEAD OF LOW PRESSURE. && .AVIATION /03Z SATURDAY THROUGH WEDNESDAY/... SHORT TERM...EXPECT IFR CONDITIONS TONIGHT IN RAIN SHOWERS AS THE FRONT MOVES THROUGH. VFR CONDITIONS SHOULD RETURN QUICKLY TOMORROW MORNING AS THE FRONT PULLS OFFSHORE. LONG TERM...VFR CONDITIONS WILL PREVAIL THROUGH TUESDAY. TUESDAY NIGHT TO EARLY WEDNESDAY MORNING MVFR CONDITIONS ARE POSSIBLE IN RAIN SHOWERS ON THE COAST AS LOW PRESSURE MOVES THROUGH THE GULF OF MAINE. VFR CONDITIONS WILL RETURN DURING THE LATE MORNING. && .MARINE... SHORT TERM...WILL LEAVE SMALL CRAFT ADVISORY IN PLACE TONIGHT AND TOMORROW. WINDS WILL GUST TO NEAR GALE WARNING CRITERIA TONIGHT AS THE WINDS INCREASE AHEAD OF THE COLD FRONT...BUT EXPECT THEM TO STAY PRIMARILY IN THE SCA CATEGORY. LONG TERM...WINDS AND SEAS INCREASE TO SMALL CRAFT LEVELS WEDNESDAY AND THURSDAY AHEAD OF AND BEHIND A COLD FRONT. && .FIRE WEATHER... NO SIGNIFICANT FIRE WEATHER CONCERNS UNTIL PERHAPS SUNDAY OR MONDAY. PRECIPITATION TONIGHT AND COOL TEMPERATURES TOMORROW SHOULD KEEP THINGS QUIET. ONCE THE DRIER AIR MOVES IN AND THE TEMPERATURES BEGIN TO RECOVER SUNDAY AND MONDAY FIRE WEATHER WILL ONCE AGAIN BECOME A CONCERN. && .GYX WATCHES/WARNINGS/ADVISORIES... ME...NONE. NH...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 10 PM EDT SATURDAY FOR ANZ150>154. && $$ NEAR TERM...LEGRO
AREA FORECAST DISCUSSION...UPDATED
NWS GRAY ME
824 PM EDT FRI APR 19 2013 .SYNOPSIS... A COLD FRONT WILL CROSS THE AREA TONIGHT. A TROUGH OF LOW PRESSURE REMAINS OVER THE REGION THROUGH SATURDAY. HIGH PRESSURE BUILDS IN SUNDAY THROUGH TUESDAY. WEAK LOW PRESSURE PASSES OFFSHORE ON WEDNESDAY. A COLD FRONT MOVES THROUGH FROM WEST TO EAST LATE WEDNESDAY NIGHT INTO THURSDAY. HIGH PRESSURE RETURNS FOR THE END OF THE WEEK. && .NEAR TERM /THROUGH SATURDAY/... UPDATE...NO MAJOR CHANGES TO THE CURRENT FCST. CONVECTIVE SHRA WITH EMBEDDED TSTMS ARE ADVANCING INTO THE HUDSON VALLEY ATTM. REMAINING INSTABILITY IS LIMITED TO THE CATSKILLS...AND THIS IS WHERE CURRENT SVR WARNINGS ARE IN EFFECT. THIS INSTABILITY WILL REMAIN ELEVATED ACROSS SRN NH AND EXTREME SWRN ME...SO DON/T EXPECT SVR WX. HOWEVER...MID LVL LAPSE RATES REMAIN ON THE ORDER OF 7 C/KM...SO TSTMS SHOULD BE ABLE TO MAINTAIN THEMSELVES INTO THE REGION. WILL CONTINUE WITH ISOLD THUNDER WORDING IN THE GRIDS. IN ADDITION...STRONG WINDS ALOFT MAY BRIEFLY MIX DOWN WITH FROPA...WITH GUSTY W WINDS TO 40 KT PSBL. PREVIOUS DISCUSSION...HAVE SLOWED FRONTAL PROGRESSION INTO THE CWFA THIS EVE BASED ON LATEST SATELLITE/RADAR TRENDS. REGIONAL MOSAIC INDICATES HRRR HAS A GOOD HANDLE ON CURRENT PLACEMENT SHWRS. THOUGH A PASSING SHRA IS PSBL IN ONSHORE FLOW THIS EVE...BULK OF RNFL WILL HOLD OFF UNTIL AFTER 00Z. HAVE ALSO ADDED ISOLD THUNDER BACK IN FOR SRN NH...AS IT DOES APPEAR ELEVATED INSTABILITY WILL WORK FAR ENOUGH N TO KEEP THE THREAT IN THERE. FOR QPF...BLENDED IN THE LATEST RFC GUIDANCE WITH ECMWF QPF VALUES...WHICH SEEM REPRESENTATIVE FOR A PROGRESSIVE FNT. && .SHORT TERM /SATURDAY NIGHT/... GUSTY CONDITIONS WILL SET UP BEHIND THE FRONT TOMORROW AS COLD AIR ADVECTION GETS GOING. STRONG PRESSURE GRADIENT LOOKS LIKE IT WILL QUICKLY RELAX AS THE DAY PROGRESSES...ALLOWING WINDS TO DROP OFF. HOWEVER...THE AIRMASS BEHIND THE FRONT LOOKS LIKE IT WILL BE VERY DRY. THIS WILL ALLOW TEMPERATURES TOMORROW NIGHT TO DROP QUICKLY AFTER THE WINDS DECOUPLE AND SKIES CLEAR. MOST LOCATIONS WILL SEE TEMPERATURES FALLING TO AROUND OR BELOW FREEZING. && .LONG TERM /SUNDAY THROUGH FRIDAY/... A STRETCH OF DRY WEATHER WILL DEVELOP SUNDAY THROUGH TUESDAY AS STRONG HIGH PRESSURE BUILDS IN FROM THE WEST. HIGH TEMPERATURES WILL WARM INTO THE UPPER 40S NORTH TO MID/UPPER 50S SOUTH WITH FORECASTED HIGHS ARE JUST A COUPLE DEGREES BELOW NORMAL. SUNDAY AND MONDAY IN PARTICULAR LOOK MOSTLY SUNNY. SOUTH WINDS BEGIN TO TRANSPORT MOIST AIR NORTH BY MONDAY NIGHT AS THE CENTER OF THE HIGH BEGINS TO MOVE OFFSHORE. A SOUTHERN STREAM SHORT WAVE MOVING ALONG THE EAST COAST WILL PROMPT A SURFACE LOW TO ORGANIZE SOUTH OF THE GULF OF MAINE. MOST MODELS NOW KEEP MOST OF THE ASSOCIATED PRECIPITATION SOUTH OF MAINE AND NH EVEN THOUGH CLOUDS WILL BE ON THE INCREASE. A FEW LIGHT SHOWERS WILL PROBABLY ENCROACH ON THE COAST TUESDAY NIGHT. AS THE COASTAL SYSTEM MOVES NORTH IT WILL BE ABSORBED IN A LARGER SURFACE LOW TO OUR WEST. THIS IS THE RESULT OF A DEEP LARGE SCALE TROUGH MOVING THROUGH THE CENTRAL AND EASTERN U.S. A SHORT WAVE AXIS WILL BECOME NEGATIVELY TILTED ON THURSDAY AS IT DRIVES A COLD FRONT THROUGH MAINE AND NH. THE EURO REMAINS ABOUT 6 HOURS BEHIND THE GFS WITH THE COLD FRONT AND MAIN BAND OF PRECIPITATION WHICH SHOULD MOVE THROUGH THURSDAY NIGHT. AM LEANING MORE TOWARDS THE EURO SOLUTION BASED ON THE SLOW PERPENDICULAR NATURE OF THE FLOW ALOFT. INSTABILITY LOOKS WEAK WITH THIS EVENT BUT HEAVY RAIN IS LIKELY AT TIMES WITH HIGH MOISTURE CONTENT IN PLACE. WEDNESDAY LOOKS THE WARMEST FOR THE LATTER HALF OF THE WORK WEEK WITH WARM AIR ADVECTION INCREASING AHEAD OF LOW PRESSURE. && .AVIATION /00Z SATURDAY THROUGH WEDNESDAY/... SHORT TERM...EXPECT IFR CONDITIONS TONIGHT IN RAIN SHOWERS AS THE FRONT MOVES THROUGH. VFR CONDITIONS SHOULD RETURN QUICKLY TOMORROW MORNING AS THE FRONT PULLS OFFSHORE. LONG TERM...VFR CONDITIONS WILL PREVAIL THROUGH TUESDAY. TUESDAY NIGHT TO EARLY WEDNESDAY MORNING MVFR CONDITIONS ARE POSSIBLE IN RAIN SHOWERS ON THE COAST AS LOW PRESSURE MOVES THROUGH THE GULF OF MAINE. VFR CONDITIONS WILL RETURN DURING THE LATE MORNING. && .MARINE... SHORT TERM...WILL LEAVE SMALL CRAFT ADVISORY IN PLACE TONIGHT AND TOMORROW. WINDS WILL GUST TO NEAR GALE WARNING CRITERIA TONIGHT AS THE WINDS INCREASE AHEAD OF THE COLD FRONT...BUT EXPECT THEM TO STAY PRIMARILY IN THE SCA CATEGORY. LONG TERM...WINDS AND SEAS INCREASE TO SMALL CRAFT LEVELS WEDNESDAY AND THURSDAY AHEAD OF AND BEHIND A COLD FRONT. && .FIRE WEATHER... NO SIGNIFICANT FIRE WEATHER CONCERNS UNTIL PERHAPS SUNDAY OR MONDAY. PRECIPITATION TONIGHT AND COOL TEMPERATURES TOMORROW SHOULD KEEP THINGS QUIET. ONCE THE DRIER AIR MOVES IN AND THE TEMPERATURES BEGIN TO RECOVER SUNDAY AND MONDAY FIRE WEATHER WILL ONCE AGAIN BECOME A CONCERN. && .GYX WATCHES/WARNINGS/ADVISORIES... ME...NONE. NH...NONE. MARINE...SMALL CRAFT ADVISORY UNTIL 10 PM EDT SATURDAY FOR ANZ150>154. && $$ NEAR TERM...LEGRO
AREA FORECAST DISCUSSION
NWS DULUTH MN
1150 PM CDT FRI APR 19 2013 .UPDATE... WE DROPPED THE WARNING FOR ASHLAND/IRON COUNTIES. RADAR/SATELLITE AND THE MODELS ALL SHOW AN IMPROVING TREND. VSBY HAS RISEN AT KIWD TO 10SM AS OF 1130 PM. DRIER AIR SHOULD CAUSE THE SNOW SHOWERS TO BECOME LESS NUMEROUS AND DECREASE FURTHER IN INTENSITY. WE ADDED SOME FOG TO NORTHWEST WISCONSIN AS KHYR AS BRIEFLY DROPPED TO 0.75SM IN FOG. && .AVIATION...06Z TAFS MAINLY VFR CONDITIONS WILL PREVAIL THROUGH THE PERIOD. SOME MVFR OR IFR CONDITIONS WILL REMAIN POSSIBLE THROUGH THE EARLY MORNING HOURS ALONG THE SNOWBELT REGION OF ASHLAND AND IRON COUNTIES DUE TO LAKE EFFECT SNOW/CLOUDS. SOME PATCHY FOG WILL ALSO BE POSSIBLE...AS KHYR VSBY HAS DROPPED THIS EVENING. NORTHWEST WINDS WILL GRADUALLY TURN SOUTHERLY ON SATURDAY. ANOTHER DISTURBANCE WILL CAUSE MID TO HIGH CLOUDS TO THICKEN SATURDAY AFTERNOON/EVENING...BUT ANY PRECIPITATION SHOULD HOLD OFF UNTIL AFTER 06Z. && .PREV DISCUSSION... /ISSUED 645 PM CDT FRI APR 19 2013/ UPDATE... RADAR SHOWS COVERAGE OF THE SNOW SHOWERS WERE DIMINISHING ACROSS THE ARROWHEAD AND EXTREME NORTHWEST WISCONSIN...AND VSBYS CONFIRM WITH KCKC UP TO 1.5SM. WE MAY BE ABLE TO CANCEL THE WARNINGS IN THE ARROWHEAD EARLY. GRAVITY WAVED INDUCED AREA OF SNOW SHOWERS ALSO SEEMS TO BE DIMINISHING...AND A CROSS SECTION THROUGH THAT AREA FROM THE RAP INDICATED CONDITIONS BECOMING LESS FAVORABLE AS DRIER AIR MOVES IN. WE MAY ALSO DROP THE WARNING ACROSS DOUGLAS COUNTY EARLY IF CURRENT TRENDS CONDITIONS. STRONG WINDS AND A FAVORABLE SET UP FOR LAKE EFFECT SNOW WILL KEEP SNOW SHOWERS GOING LONGER ACROSS PORTIONS OF BAYFIELD...BUT ESPECIALLY ASHLAND AND IRON COUNTIES. STRONG WINDS WERE ALSO CREATING ISSUES WITH BLOWING/DRIFTING. WE EXPECT THE WINDS TO DIMINISH AS THE EVENING PROGRESSES. AVIATION...00Z TAFS CLOUDS WERE DIMINISHING THIS EVENING OVER MINNESOTA...WITH THE SNOW SHOWERS ALSO DIMINISHING IN COVERAGE OVER NORTHEAST MINNESOTA AND EXTREME NORTHWEST WISCONSIN. WE EXPECT THE TAF SITES TO BECOME VFR THIS EVENING...WITH THE WIND DIMINISHING OVER THE NEXT 1-3 HOURS. MVFR TO LIFR CONDITIONS WILL CONTINUE THROUGH MOST OF THE EVENING ACROSS THE SNOWBELT OF THE SOUTH SHORE. VFR CONDITIONS WILL PREVAIL THROUGH THE DAY SATURDAY...WITH SOME SCATTERED TO PERHAPS BROKEN CUMULUS DEVELOPING BY AFTERNOON. PREV DISCUSSION... /ISSUED 347 PM CDT FRI APR 19 2013/ SHORT TERM...TONIGHT THROUGH SATURDAY... THE POWERFUL WINTER STORM THAT BROUGHT 1 TO 2 FEET OF SNOW TO MUCH OF THE NORTHLAND OVER THE LAST 1-2 DAYS WILL CONTINUE TO GRADUALLY WIND DOWN ACROSS THE REGION OVERNIGHT. HEAVY SNOW CONTINUED ACROSS THE ARROWHEAD...AND LOCALLY ACROSS THE SOUTH SHORE OF LAKE SUPERIOR. COOK COUNTY CONTINUES TO HAVE A TOUGH TIME KEEPING ROADS CLEARED WITH HEAVY SNOW AND INTENSE WINDS OF 40 TO 50 MPH AT TIMES. IT APPEARS THE STANDING WAVE SHOWING UP ON 88D RADAR EXTENDS NORTHWARD INTO COOK COUNTY WITH VISIBILITIES OF A QUARTER MILE OR LESS AT TIMES. ACROSS THE SOUTH SHORE...LOCALLY HEAVY SNOW SHOWERS CONTINUED ACROSS THAT AREA AS WELL. LOOKING FOR ANOTHER GOOD 1 TO 3 INCHES IN THE ARROWHEAD AND LOCALLY UP TO ANOTHER 6 INCHES FOR THE SOUTH SHORE OF LAKE SUPERIOR. HIGH PRESSURE WILL BUILD EASTWARD ACROSS THE NORTHLAND OVERNIGHT...BRINGING A GRADUAL END TO THE SNOW FROM WEST TO EAST. SOME CLEARING HAD ALREADY TAKEN PLACE IN THE WESTERN PORTION OF THE CWA. THIS CLEARING WILL SET THE STAGE FOR SOME POTENTIALLY RECORD BREAKING COLD TEMPERATURES BY SATURDAY MORNING. LOWS SHOULD RANGE FROM THE SINGLE DIGITS TO THE TEENS DUE TO CLEARING SKIES...DRIER AIR AND A SOLID SNOW PACK THAT IS QUITE UNUSUAL FOR THIS TIME OF YEAR. THERE SHOULD BE PLENTY OF SUNSHINE ON SATURDAY WITH TEMPERATURES IN THE 30S FOR DAYTIME HIGHS...WELL BELOW OUR NORMAL HIGH AROUND THE 50 DEGREE MARK. LONG TERM...SATURDAY NIGHT THROUGH FRIDAY... THE NEXT STORM SYSTEM WILL BE AFFECTING THE FORECAST AREA. THE MODELS ARE DIFFERENT IN THEIR SOLUTIONS WITH THE MOVEMENT OF THE LOW PRESSURE CENTER. THE NAM AND GFS HAS THE CENTER IN SOUTHERN CANADA WITH A TROUGH ACROSS THE FORECAST AREA. THE ECMWF AND GEM HAS THE CENTER MOVING ACROSS THE BORDER. PRECIP MOVES INTO THE SOUTHERN PORTIONS OF THE FORECAST AREA SUNDAY MORNING AND SPREADS NORTH. THE PTYPE WILL BE SNOW THIS MORNING AND SWITCH OVER TO RAIN BY MIDDAY. THE LOW MOVES EAST BY MONDAY MORNING ENDING THE MAIN PART OF PRECIP WEST TO EAST SUNDAY NIGHT. THERE WILL BE A BREAK BEFORE THE NEXT STORM SYSTEM AFFECT THE REGION MONDAY NIGHT. MODELS INDICATE THE PRECIP WILL BE MAINLY CONFINED TO NW WI. THE QUESTION FOR THIS SYSTEM IS IF THE RAIN/SNOW SPREADS INTO DULUTH. RIGHT NOW...WE WILL KEEP IT MAINLY SOUTH OF THE TWIN PORTS. THE PROBLEMS WITH THE TWO SYSTEM WILL BE THE PRECIP AMOUNTS OF 0.33 TO 0.75 INCHES WHICH WILL ADD ADDITIONAL MOISTURE TO THE SNOW PACK. THERE WILL BE A WARMUP NEXT WEEK WITH TEMPS INTO THE 40S WHICH START THE SNOWMELT. && .POINT TEMPS/POPS... DLH 13 36 24 40 / 0 0 50 60 INL 7 36 23 42 / 0 0 50 60 BRD 12 37 28 45 / 0 10 70 60 HYR 8 37 24 45 / 70 0 60 70 ASX 16 36 23 43 / 80 0 40 50 && .DLH WATCHES/WARNINGS/ADVISORIES... MN...NONE. WI...NONE. LS...SMALL CRAFT ADVISORY UNTIL 9 AM CDT SATURDAY FOR LSZ121-146>148. SMALL CRAFT ADVISORY UNTIL 4 AM CDT SATURDAY FOR LSZ140>142. && $$ SHORT TERM...MELDE AVIATION...MELDE
AREA FORECAST DISCUSSION
NWS BISMARCK ND
1259 AM CDT SAT APR 20 2013 .UPDATE... ISSUED AT 1259 AM CDT SAT APR 20 2013 LATEST RADAR IMAGERY AT 0545Z SHOWS SOME LIGHT RETURNS OVER THE FAR WEST AND SOUTHWEST. HOWEVER...AT THIS TIME THERE HAVE BEEN NO SURFACE OBSERVATIONS REPORTING ANY PRECIP REACHING THE SURFACE. SO BASED OFF THE LATEST RUN OF THE RAP (04Z)...HAVE SCALED BACK POPS OVER THE NEXT FEW HOURS FOR THE WEST. OTHERWISE...FORECAST IS IN GOOD SHAPE AND MADE ADJUSTMENTS BASED OFF LATEST OBSERVATIONS AND TRENDS AT 05Z. UPDATE ISSUED AT 956 PM CDT FRI APR 19 2013 BASED ON LATEST SHORT RANGE MODEL TRENDS...HAVE SLOWED TIMING OF POPS FROM WEST TO EAST...OVERNIGHT THROUGH SATURDAY. EXPECTED QPF AMOUNTS STILL SUPPORT AROUND AN INCH OF NEW SNOW THROUGH THE AFTERNOON. && .SHORT TERM...(THIS EVENING THROUGH SATURDAY) ISSUED AT 325 PM CDT FRI APR 19 2013 LATEST SATELLITE IMAGERY SHOWS CLEAR SKIES OVER ALL BUT THE FAR SOUTHWEST PORTION OF THE CWA THIS AFTERNOON. SURFACE LOW PRESSURE IS DEEPENING OVER THE CANADIAN AND NORTHERN U.S. ROCKIES WHILE SURFACE HIGH PRESSURE REMAINS OVER THE CENTRAL DAKOTAS INTO MANITOBA AND SASKATCHEWAN. AREA RADARS INDICATED LIGHT REFLECTIVITIES OVER CENTRAL MONTANA...WEST OF GLASGOW AND MILES CITY. THE MAIN FORECAST PROBLEM FOR TONIGHT AND SATURDAY WILL BE TRACKING THIS AREA OF WARM ADVECTION EAST ACROSS THE LOCAL AREA. MODELS ARE CONSISTENT IN BRINGING A BAND OF WARM ADVECTION WEST TO EAST ACROSS THE AREA...BEGINNING THIS EVENING IN THE FAR WEST. MODELS ARE A LITTLE SLOWER THAN THE PREVIOUS FORECAST AND THEREFORE THE MAIN CHANGE WAS TO SLOW THE TIMING OF THIS SYSTEM. WITH THE LEADING EDGE MOVING INTO THE FAR WEST THIS EVENING...WE COULD SEE A PRECIPITATION BEGIN AS RAIN OR A RAIN/SNOW MIX IN THE FAR SOUTHWEST. FORECAST SOUNDINGS INDICATE THIS WOULD BE SHORT LIVED BEFORE A CHANGE TO ALL SNOW. THE MAJORITY OF PRECIPITATION SHOULD FALL AS SNOW AS IT WORKS ITS WAY INTO CENTRAL NORTH DAKOTA TONIGHT...THEN ACROSS THE CENTRAL ON SATURDAY. ON SATURDAY...AFTER THE MAIN WARM ADVECTION FORCING...UPPER LEVEL FLOW REMAINS CONDUCIVE FOR SHORTWAVES TO TRAVERSE THE FORECAST AREA. WITH AFTERNOON HEATING WE ALSO BECOME SLIGHTLY UNSTABLE IN THE FAR SOUTHWEST. WOULD NOT BE SURPRISED TO SEE SOME THUNDERSTORM ACTIVITY APPROACH THE SOUTHWEST SATURDAY AFTERNOON...BUT WITH SOME SNOW REMAINING ON THE GROUND...THINK THIS MAY BE JUST ENOUGH TO SUPPRESS SURFACE HEATING ENOUGH FOR CONVECTION. WILL KEEP IT OUT FOR NOW. WE WILL SEE WARMER TEMPERATURES IN THE WEST WITH HIGHS APPROACHING 50 DEGREES...WHICH STILL REMAINS BELOW NORMAL. .LONG TERM...(SATURDAY NIGHT THROUGH FRIDAY) ISSUED AT 325 PM CDT FRI APR 19 2013 THE HIGHLIGHT OF THE EXTENDED FORECAST IS THE CONTINUATION OF BELOW NORMAL TEMPERATURES ACROSS WESTERN AND CENTRAL NORTH DAKOTA UNDER A BROAD UPPER LEVEL LONGWAVE CONUS TROUGH. THE 12 UTC DETERMINISTIC SUITE IS IN GOOD AGREEMENT ON THE OVERALL PATTERN THROUGH THE EXTENDED AND UTILIZED A BLEND FOR MOST FORECAST FIELDS. THIS WEEKEND DOES LOOK TO BE A BIT UNSETTLED AS ENERGY CURRENTLY ACROSS FAR NORTHWEST BRITISH COLUMBIA PROPAGATES INTO THE NORTHERN PLAINS. SCATTERED PRECIPITATION IS EXPECTED DURING THE DAYTIME SATURDAY WITH MORE WIDESPREAD AND RELATIVELY HEAVIER PRECIPITATION SATURDAY NIGHT INTO SUNDAY...ESPECIALLY ACROSS NORTHERN NORTH DAKOTA CLOSER TO THE SHORTWAVE. RAIN IS FAVORED ACROSS SOUTHERN NORTH DAKOTA DURING THE DAYTIME...WITH A MIX OR ALL SNOW AT NIGHT. MOSTLY SNOW IS EXPECTED ACROSS NORTHERN NORTH DAKOTA WITH COOLER AIR IN PLACE. ANY SNOWFALL AMOUNTS WILL BE MINIMAL...WITH PERHAPS AN INCH OF ACCUMULATION ALONG AND NORTH OF US HIGHWAY 2. WHILE TEMPERATURES ARE EXPECTED TO REMAIN BELOW AVERAGE THROUGH NEXT WEEK UNDER NORTHWEST FLOW ALOFT...THE UPPER LEVEL TROUGH AXIS DOES SLOWLY SHIFT EAST NEXT WEEK...ALLOWING FOR A SLOW WARM UP RELATIVE TO THE CHILLY WEEKEND. THE 12 UTC DETERMINISTIC SOLUTIONS AND ENSEMBLES CONTINUE TO PUSH BACK THE PATTERN CHANGE TO NEAR NORMAL TEMPERATURES WITH UPPER LEVEL RIDGING TO PERHAPS THE APRIL 30 OR MAY 1 TIMEFRAME. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT) ISSUED AT 1259 AM CDT SAT APR 20 2013 SOUTHEAST FLOW WILL INCREASE THROUGH THIS MORNING FROM WEST TO EAST ACROSS ALL TERMINALS. LIGHT SNOW WILL DEVELOP FOR KDIK/KISN AFTER 10Z...KBIS/KMOT AFTER 15Z...AND KJMS AFTER 21Z. THERE WILL BE A PERIOD OF A RAIN/SNOW MIX AT KDIK/KISN/KBIS DURING THE LATE MORNING...AND CONTINUE THROUGH 03/04Z FOR KBIS/ISN...AND THROUGH THE REMAINDER OF THE 06Z TAF CYCLE FOR KDIK. && .BIS WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...LTH SHORT TERM...TWH LONG TERM...AYD AVIATION...LTH
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
1132 PM CDT FRI APR 19 2013 .SHORT TERM...(THIS EVENING THROUGH SATURDAY) ISSUED AT 313 PM CDT FRI APR 19 2013 MAIN FORECAST CONCERNS ARE ON LINGERING SNOW/RAIN SHOWERS THIS EVENING. FOCUS THEN TURNS TO PRECIPITATION CHANCES AND TEMPERATURES SATURDAY NIGHT INTO SUNDAY. LATEST WATER VAPOR IMAGERY AND 500 MB RAP ANALYSIS PLACED LOW PRESSURE OVER CENTRAL LAKE SUPERIOR...MOVING NORTHEAST. CYCLONIC FLOW WAS IMPACTING THE FORECAST AREA ON THE BACK SIDE OF THE LOW. THIS CYCLONIC FLOW COUPLED WITH STEEP LAPSE RATES HAS PRODUCED WIDESPREAD SNOW SHOWERS THROUGH MUCH OF THE DAY. SCATTERED SNOW SHOWERS WILL LINGER INTO THE EARLY EVENING THEN DISSIPATE AS THE LOW LIFTS NORTHEAST AND SURFACE TEMPERATURES COOL. HIGH PRESSURE WILL GRADUALLY BUILD INTO THE FORECAST AREA TONIGHT INTO EARLY SATURDAY MORNING. IT WILL TAKE SOME TIME TO SCOUR OUT THE LOW LEVEL MOISTURE AND THE NAM AND GFS HANG ONTO THIS MOISTURE WELL INTO THE EVENING HOURS. LOOKING AT OBSERVATIONS AND VISIBLE SATELLITE UPSTREAM ACROSS WESTERN INTO CENTRAL MINNESOTA THERE IS A WELL DEFINED CLEARING LINE AND A LACK OF CUMULUS DEVELOPMENT TODAY THANKS TO THE FRESH SNOW COVER IN PLACE KEEPING SURFACE TEMPERATURES COOL. PLAN ON A GRADUAL CLEARING TREND FROM WEST TO EAST TONIGHT...WITH THE CLEARING APPROACHING THE MISSISSIPPI RIVER LATE IN THE EVENING THEN PROGRESSING EAST THROUGH THE OVERNIGHT HOURS. SKIES WILL BE MOSTLY SUNNY SATURDAY MORNING AS COOL HIGH PRESSURE SLIDES OVERHEAD. THE SUNNY SKIES WILL BE SHORT LIVED ON SATURDAY AS A SHORTWAVE TROUGH APPROACHES FROM THE NORTHERN PLAINS WITH INCREASING HIGH CLOUDS EXPECTED DURING THE LATE AFTERNOON HOURS. THE HIGH WILL QUICKLY PUSH EAST OF THE REGION SATURDAY EVENING AS THE SHORTWAVE APPROACHES THE UPPER MISSISSIPPI RIVER VALLEY AND SURFACE LOW PRESSURE DEEPENS OVER THE CENTRAL/NORTHERN PLAINS. PLAN ON HIGH TEMPERATURES ON SATURDAY RANGING FROM THE UPPER 30S OVER NORTH CENTRAL WISCONSIN TO THE MID 40S ACROSS NORTHEAST IOWA. .LONG TERM...(SATURDAY NIGHT THROUGH FRIDAY) ISSUED AT 313 PM CDT FRI APR 19 2013 SOUTHERLY FLOW WILL INCREASE ACROSS THE REGION AHEAD OF THE LOW. STRONG 850MB WARM AIR ADVECTION INCREASES ACROSS THE FORECAST AREA IN THE 6Z-12Z TIMEFRAME. PLAN ON RAIN/SNOW SHOWERS DEVELOPING ACROSS THE AREA AS THIS SHORTWAVE MOVES IN AND WARM AIR ADVECTION INCREASES. FORECAST SOUNDINGS SHOW A DRY LAYER NEAR THE SURFACE...MAINLY BELOW 3KFT. AS PRECIPITATION FALLS INTO THIS LAYER...EVAPORATION WILL COOL THE LOWER LEVELS LEADING TO A SWITCH FROM RAIN INITIALLY OVER TO A PERIOD OF SNOW. SURFACE TEMPERATURES WARM IN THE 12 TO 15Z...SOUTH OF INTERSTATE 94...SO EXPECTING TO SEE A SWITCH OVER TO ALL RAIN ACROSS THESE AREAS. NORTH OF I-94 IT WILL TAKE A LITTLE LONGER FOR SURFACE TEMPERATURES TO WARM WHERE THE SWITCH OVER LOOKS TO OCCUR AFTER 17Z. A SLIGHTLY WARMER AND UNSTABLE AIRMASS MOVES INTO THE AREA SUNDAY AFTERNOON WITH 0-3 KM MUCAPE VALUES INCREASING TO AROUND 500 J/KG. COULD SEE SOME ISOLATED TO SCATTERED THUNDERSTORMS SUNDAY AFTERNOON INTO SUNDAY EVENING. THERE IS THE POTENTIAL FOR SOME SMALL HAIL WITH ANY THUNDERSTORMS THAT DEVELOP WEST OF THE MISSISSIPPI RIVER. CAPE AND SHEAR PROFILES ARE RATHER WEAK SO NOT ANTICIPATING SEVERE THUNDERSTORMS AT THIS TIME. THERE ARE SOME INDICATIONS THAT THE FRONT COULD SLIDE THROUGH LATER...PLACING THUNDERSTORM POTENTIAL OVER THE FORECAST AREA AGAIN ON MONDAY. IF THIS SCENARIO PLAYS OUT...THERE IS THE POSSIBILITY OF THUNDERSTORMS AGAIN ON MONDAY MAINLY ALONG AND SOUTH OF INTERSTATE 90. A SECONDARY TROUGH DIVES SOUTHEAST OUT OF WESTERN CANADA AND INTO THE PLAINS SUNDAY NIGHT INTO MONDAY. A COLD FRONT...STRETCHING FROM NORTHEAST MINNESOTA SOUTHWEST INTO SOUTHEASTERN SOUTH DAKOTA...WILL SLIDE SOUTHEAST SUNDAY NIGHT THROUGH MONDAY AS THE WAVE DIGS SOUTH. SOME DIFFERENCES NOTED IN THE FORECAST MODELS MONDAY INTO TUESDAY AS ANOTHER WAVE DIVES SOUTH OUT OF THE PACIFIC NORTHWEST AND INTO THE CENTRAL PLAINS. THE GFS PUSHES THE COLD FRONT SOUTH ON MONDAY AS THE SHORTWAVE EJECTS OUT OF THE CENTRAL PLAINS AND INTERACTS WITH THE FRONT OVER THE FORECAST AREA. THIS SCENARIO WOULD PRODUCE SIGNIFICANT RAINFALL AND EVEN SOME SNOW ACROSS PORTIONS OF SOUTHEAST MINNESOTA THROUGH NORTH CENTRAL WISCONSIN MONDAY NIGHT INTO TUESDAY. THE GEM SOLUTION IS ALSO ON BOARD WITH THE GFS BUT IS SLOWER WITH THE WAVE BRINGING IT INTO THE FORECAST AREA TUESDAY INTO TUESDAY NIGHT. THE 19.12 ECMWF IS MORE IN LINE WITH THE GEM SOLUTION AND ALSO PRODUCES A SWATH OF ACCUMULATING SNOW ACROSS SOUTHEAST MINNESOTA THROUGH NORTH CENTRAL WISCONSIN WITH TEMPERATURES WARM ENOUGH FOR RAIN TO MIX IN OVER PORTIONS OF NORTHEAST IOWA INTO FAR SOUTHWEST WISCONSIN. GIVEN THE UNCERTAINTIES IN THE TRACK AND TINNING OF THIS SYSTEM ITS DIFFICULT TO PIN DOWN EXACT PRECIPITATION TYPE AND AMOUNTS. WILL HAVE TO KEEP A VERY CLOSE WATCH ON THIS SYSTEM IMPACTING THE REGION IN THE MONDAY THROUGH WEDNESDAY TIMEFRAME. WELL BELOW NORMAL TEMPERATURES ARE EXPECTED THE LAST HALF OF THE WORK WEEK AS NORTHWEST FLOW ALOFT SETS UP OVER THE REGION. AFTER A BRIEF RETURN TO SLIGHTLY MORE SEASONABLE TEMPERATURES SUN-MON WITH HIGHS IN THE 50S...HIGHS WILL FALL BACK INTO THE 40S TO AROUND 50 WEDNESDAY INTO THURSDAY. THE ACTIVE PATTERN CONTINUES THURSDAY INTO FRIDAY AS ANOTHER TROUGH TAKES AIM ON THE REGION VIA NORTHWEST FLOW ALOFT. THIS FEATURE WILL BRING RAIN AND SNOW CHANCES TO THE AREA ON THURSDAY. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT) ISSUED AT 1132 PM CDT FRI APR 19 2013 SKIES HAVE GRADUALLY BEEN CLEARING ACROSS THE REGION WITH SNOW SHOWER ACTIVITY GREATLY DECREASING AS WELL. EXPECT THAT SKY CONDITIONS WILL CONTINUE TO CLEAR THROUGH THE OVERNIGHT HOURS WITH SOME FAIR WEATHER VFR CU POSSIBLY FORMING LATE TOMORROW MORNING/EARLY AFTERNOON. WINDS WILL GO LIGHT AS A RIDGE OF HIGH PRESSURE MOVES INTO THE REGION. MID LEVEL CLOUD COVER WILL THEN BE ON THE INCREASE TOMORROW EVENING AS THE NEXT SYSTEM MOVES INTO THE REGION FROM THE WEST. && .HYDROLOGY... ISSUED AT 313 PM CDT FRI APR 19 2013 FLOODING IS CURRENTLY OCCURRING ALONG PORTIONS OF THE BLACK RIVER. PORTIONS OF THE TREMPEALEAU RIVER ARE RUNNING NEAR OR SLIGHTLY ABOVE FLOOD STAGE. RECENT RAINFALL WILL KEEP THESE RIVERS NEAR OR ABOVE FLOOD STAGE THROUGH THE WEEKEND. WET CONDITIONS WILL PERSIST INTO THE EARLY PART OF THE WORK WEEK. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...NONE. MN...NONE. IA...NONE. && $$ SHORT TERM...WETENKAMP LONG TERM...WETENKAMP AVIATION...HALBACH HYDROLOGY...WETENKAMP
AREA FORECAST DISCUSSION
NWS LA CROSSE WI
623 PM CDT FRI APR 19 2013 .SHORT TERM...(THIS EVENING THROUGH SATURDAY) ISSUED AT 313 PM CDT FRI APR 19 2013 MAIN FORECAST CONCERNS ARE ON LINGERING SNOW/RAIN SHOWERS THIS EVENING. FOCUS THEN TURNS TO PRECIPITATION CHANCES AND TEMPERATURES SATURDAY NIGHT INTO SUNDAY. LATEST WATER VAPOR IMAGERY AND 500 MB RAP ANALYSIS PLACED LOW PRESSURE OVER CENTRAL LAKE SUPERIOR...MOVING NORTHEAST. CYCLONIC FLOW WAS IMPACTING THE FORECAST AREA ON THE BACK SIDE OF THE LOW. THIS CYCLONIC FLOW COUPLED WITH STEEP LAPSE RATES HAS PRODUCED WIDESPREAD SNOW SHOWERS THROUGH MUCH OF THE DAY. SCATTERED SNOW SHOWERS WILL LINGER INTO THE EARLY EVENING THEN DISSIPATE AS THE LOW LIFTS NORTHEAST AND SURFACE TEMPERATURES COOL. HIGH PRESSURE WILL GRADUALLY BUILD INTO THE FORECAST AREA TONIGHT INTO EARLY SATURDAY MORNING. IT WILL TAKE SOME TIME TO SCOUR OUT THE LOW LEVEL MOISTURE AND THE NAM AND GFS HANG ONTO THIS MOISTURE WELL INTO THE EVENING HOURS. LOOKING AT OBSERVATIONS AND VISIBLE SATELLITE UPSTREAM ACROSS WESTERN INTO CENTRAL MINNESOTA THERE IS A WELL DEFINED CLEARING LINE AND A LACK OF CUMULUS DEVELOPMENT TODAY THANKS TO THE FRESH SNOW COVER IN PLACE KEEPING SURFACE TEMPERATURES COOL. PLAN ON A GRADUAL CLEARING TREND FROM WEST TO EAST TONIGHT...WITH THE CLEARING APPROACHING THE MISSISSIPPI RIVER LATE IN THE EVENING THEN PROGRESSING EAST THROUGH THE OVERNIGHT HOURS. SKIES WILL BE MOSTLY SUNNY SATURDAY MORNING AS COOL HIGH PRESSURE SLIDES OVERHEAD. THE SUNNY SKIES WILL BE SHORT LIVED ON SATURDAY AS A SHORTWAVE TROUGH APPROACHES FROM THE NORTHERN PLAINS WITH INCREASING HIGH CLOUDS EXPECTED DURING THE LATE AFTERNOON HOURS. THE HIGH WILL QUICKLY PUSH EAST OF THE REGION SATURDAY EVENING AS THE SHORTWAVE APPROACHES THE UPPER MISSISSIPPI RIVER VALLEY AND SURFACE LOW PRESSURE DEEPENS OVER THE CENTRAL/NORTHERN PLAINS. PLAN ON HIGH TEMPERATURES ON SATURDAY RANGING FROM THE UPPER 30S OVER NORTH CENTRAL WISCONSIN TO THE MID 40S ACROSS NORTHEAST IOWA. .LONG TERM...(SATURDAY NIGHT THROUGH FRIDAY) ISSUED AT 313 PM CDT FRI APR 19 2013 SOUTHERLY FLOW WILL INCREASE ACROSS THE REGION AHEAD OF THE LOW. STRONG 850MB WARM AIR ADVECTION INCREASES ACROSS THE FORECAST AREA IN THE 6Z-12Z TIMEFRAME. PLAN ON RAIN/SNOW SHOWERS DEVELOPING ACROSS THE AREA AS THIS SHORTWAVE MOVES IN AND WARM AIR ADVECTION INCREASES. FORECAST SOUNDINGS SHOW A DRY LAYER NEAR THE SURFACE...MAINLY BELOW 3KFT. AS PRECIPITATION FALLS INTO THIS LAYER...EVAPORATION WILL COOL THE LOWER LEVELS LEADING TO A SWITCH FROM RAIN INITIALLY OVER TO A PERIOD OF SNOW. SURFACE TEMPERATURES WARM IN THE 12 TO 15Z...SOUTH OF INTERSTATE 94...SO EXPECTING TO SEE A SWITCH OVER TO ALL RAIN ACROSS THESE AREAS. NORTH OF I-94 IT WILL TAKE A LITTLE LONGER FOR SURFACE TEMPERATURES TO WARM WHERE THE SWITCH OVER LOOKS TO OCCUR AFTER 17Z. A SLIGHTLY WARMER AND UNSTABLE AIRMASS MOVES INTO THE AREA SUNDAY AFTERNOON WITH 0-3 KM MUCAPE VALUES INCREASING TO AROUND 500 J/KG. COULD SEE SOME ISOLATED TO SCATTERED THUNDERSTORMS SUNDAY AFTERNOON INTO SUNDAY EVENING. THERE IS THE POTENTIAL FOR SOME SMALL HAIL WITH ANY THUNDERSTORMS THAT DEVELOP WEST OF THE MISSISSIPPI RIVER. CAPE AND SHEAR PROFILES ARE RATHER WEAK SO NOT ANTICIPATING SEVERE THUNDERSTORMS AT THIS TIME. THERE ARE SOME INDICATIONS THAT THE FRONT COULD SLIDE THROUGH LATER...PLACING THUNDERSTORM POTENTIAL OVER THE FORECAST AREA AGAIN ON MONDAY. IF THIS SCENARIO PLAYS OUT...THERE IS THE POSSIBILITY OF THUNDERSTORMS AGAIN ON MONDAY MAINLY ALONG AND SOUTH OF INTERSTATE 90. A SECONDARY TROUGH DIVES SOUTHEAST OUT OF WESTERN CANADA AND INTO THE PLAINS SUNDAY NIGHT INTO MONDAY. A COLD FRONT...STRETCHING FROM NORTHEAST MINNESOTA SOUTHWEST INTO SOUTHEASTERN SOUTH DAKOTA...WILL SLIDE SOUTHEAST SUNDAY NIGHT THROUGH MONDAY AS THE WAVE DIGS SOUTH. SOME DIFFERENCES NOTED IN THE FORECAST MODELS MONDAY INTO TUESDAY AS ANOTHER WAVE DIVES SOUTH OUT OF THE PACIFIC NORTHWEST AND INTO THE CENTRAL PLAINS. THE GFS PUSHES THE COLD FRONT SOUTH ON MONDAY AS THE SHORTWAVE EJECTS OUT OF THE CENTRAL PLAINS AND INTERACTS WITH THE FRONT OVER THE FORECAST AREA. THIS SCENARIO WOULD PRODUCE SIGNIFICANT RAINFALL AND EVEN SOME SNOW ACROSS PORTIONS OF SOUTHEAST MINNESOTA THROUGH NORTH CENTRAL WISCONSIN MONDAY NIGHT INTO TUESDAY. THE GEM SOLUTION IS ALSO ON BOARD WITH THE GFS BUT IS SLOWER WITH THE WAVE BRINGING IT INTO THE FORECAST AREA TUESDAY INTO TUESDAY NIGHT. THE 19.12 ECMWF IS MORE IN LINE WITH THE GEM SOLUTION AND ALSO PRODUCES A SWATH OF ACCUMULATING SNOW ACROSS SOUTHEAST MINNESOTA THROUGH NORTH CENTRAL WISCONSIN WITH TEMPERATURES WARM ENOUGH FOR RAIN TO MIX IN OVER PORTIONS OF NORTHEAST IOWA INTO FAR SOUTHWEST WISCONSIN. GIVEN THE UNCERTAINTIES IN THE TRACK AND TINNING OF THIS SYSTEM ITS DIFFICULT TO PIN DOWN EXACT PRECIPITATION TYPE AND AMOUNTS. WILL HAVE TO KEEP A VERY CLOSE WATCH ON THIS SYSTEM IMPACTING THE REGION IN THE MONDAY THROUGH WEDNESDAY TIMEFRAME. WELL BELOW NORMAL TEMPERATURES ARE EXPECTED THE LAST HALF OF THE WORK WEEK AS NORTHWEST FLOW ALOFT SETS UP OVER THE REGION. AFTER A BRIEF RETURN TO SLIGHTLY MORE SEASONABLE TEMPERATURES SUN-MON WITH HIGHS IN THE 50S...HIGHS WILL FALL BACK INTO THE 40S TO AROUND 50 WEDNESDAY INTO THURSDAY. THE ACTIVE PATTERN CONTINUES THURSDAY INTO FRIDAY AS ANOTHER TROUGH TAKES AIM ON THE REGION VIA NORTHWEST FLOW ALOFT. THIS FEATURE WILL BRING RAIN AND SNOW CHANCES TO THE AREA ON THURSDAY. && .AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SATURDAY EVENING) ISSUED AT 623 PM CDT FRI APR 19 2013 THE MAIN FOCUS WITH THE FORECAST IS WITHIN THE NEXT 6 HOURS AND WHEN THE SHOW/RAIN SHOWER ACTIVITY ENDS THIS EVENING ALONG WITH WHEN SKIES MAY EVENTUALLY CLEAR. DUE TO THE CONVECTIVE NATURE OF THESE SHOWERS...EXPECT THAT THE CLOUD AND RAIN/SNOW SHOWER COVERAGE SHOULD DIMINISH INTO THE EVENING HOURS BEFORE SKIES EVENTUALLY CLEAR OVERNIGHT AS THE DRIER AIR MOVES IN. KEPT THE TRENDS OF THESE SHOWERS ENDING AROUND 3-4Z THIS EVENING WITH CEILINGS REMAINING VFR BETWEEN 3-6KFT THROUGHOUT. VISIBILITY MAY BRIEFLY DROP TO MVFR OR LOWER...BUT IT WILL ONLY LAST FOR A MATTER OF MINUTES BEFORE IMPROVING BACK TO VFR. A RIDGE OF HIGH PRESSURE WILL MOVE IN TOMORROW MORNING AND BRING LIGHTER WINDS AND CLEAR SKIES ALONG WITH IT. && .HYDROLOGY... ISSUED AT 313 PM CDT FRI APR 19 2013 FLOODING IS CURRENTLY OCCURRING ALONG PORTIONS OF THE BLACK RIVER. PORTIONS OF THE TREMPEALEAU RIVER ARE RUNNING NEAR OR SLIGHTLY ABOVE FLOOD STAGE. RECENT RAINFALL WILL KEEP THESE RIVERS NEAR OR ABOVE FLOOD STAGE THROUGH THE WEEKEND. WET CONDITIONS WILL PERSIST INTO THE EARLY PART OF THE WORK WEEK. && .ARX WATCHES/WARNINGS/ADVISORIES... WI...NONE. MN...NONE. IA...NONE. && $$ SHORT TERM...WETENKAMP LONG TERM...WETENKAMP AVIATION...HALBACH HYDROLOGY...WETENKAMP
AREA FORECAST DISCUSSION...CORRECTED
NWS GRAND JUNCTION CO
414 AM MDT SAT APR 20 2013 CORRECTED TIMING OF AVIATION SECTION .SHORT TERM...(TODAY THROUGH SUNDAY) ISSUED AT 343 AM MDT SAT APR 20 2013 TODAY...SHORTWAVE AND ASSOCIATED SFC FRONT MAKING QUICK PROGRESS ACROSS THE GREAT BASIN THIS MORNING AND WILL BE PUSHING EAST ACROSS WESTERN COLORADO TODAY. AREAS OF LIGHT RAIN AND SNOW FALLING ACROSS THE REGION WILL PEAK IN AREAL COVERAGE THIS MORNING AS THE MAIN FORCING ASSOCIATED WITH THE PASSING WAVE ARRIVES. RADAR ECHOES HAVE BEEN ON THE INCREASE THIS MORNING AND MORNING HRRR AND RAP MODELS BOTH INDICATING A FAIRLY ACTIVE START TO THE DAY WITH SNOW LEVELS RUNNING AROUND 6K. BEST ACCUMULATIONS LOOKS TO BE CONFINED TO THE HIGHER ELEVATIONS...WITH THE NORTHERN MOUNTAINS REMAINING FAVORED ATTM...WITH CURRENT ADVISORIES ON TRACK. HAVE BOOSTED POPS AND SHAVED TEMPS A BIT FROM MOS VALUES. TONIGHT...THOUGH DYNAMICAL SUPPORT HAS SHIFTED EAST SNOW WILL CONTINUE ACROSS NW COLORADO WITH FORECAST SOUNDINGS INDICATING A MOIST NW OROGRAPHIC FLOW THROUGH MIDNIGHT. THEN THE FLOW SLACKENS SOMEWHAT AND BACKS TO SW. THE MOIST LAYER ALSO SHRINKS TO BELOW 12KFT FOR LITTLE TO NO ACCUMULATING SNOWFALL. TEMPERATURES STAY NEAR NORMAL NORTH UNDER CLOUD COVER...ABOUT 5 DEGREES BELOW NORMAL FOR THE CENTRAL AND SOUTH UNDER MOSTLY CLEAR SKIES. SUNDAY...WEST WINDS INCREASE AS THE NEXT OPEN WAVE WORKS IN FROM THE NW. THE JET REMAINS ORIENTED NEAR THE CO-WY BORDER EFFECTIVELY KEEPING THE COLD AIR AND DYNAMICS NORTH OF THIS FORECAST AREA. AFTERNOON HEATING AND MARGINAL MOISTURE PRODUCE A SLIVER OF AFTERNOON CAPE MAINLY IN THE NW CO MTNS FOR SCATTERED SNOW SHOWERS. SNOW LEVEL WILL BE AROUND 8KFT NORTH TO 9KFT CENTRAL. .LONG TERM...(SUNDAY NIGHT THROUGH FRIDAY) ISSUED AT 343 AM MDT SAT APR 20 2013 SUNDAY NIGHT-MONDAY NIGHT...ENHANCING ENERGY DEVELOPS A TROUGH AND BEGINS TO PUSH THE JET AND ASSOCIATED COLD FRONT NW-SE THROUGH THE REGION. THE BEST DYNAMICAL SUPPORT SHIFTS EAST OF THE CONTINENTAL DIVIDE WITH SNOW ACCUMULATIONS NOW LOOKING MEAGER EXCEPT ALONG THE COLORADO SPINE WHERE A CONVECTIVE COMPONENT MAY PRODUCE LOCALIZED ENHANCED SNOW ACCUMULATIONS. BREEZY TO WINDY CONDITIONS CONTINUE ON MONDAY AS THE COLD FRONT WORKS THROUGH THE REGION WITH A COOLER DRIER AIR MASS WORKING IN OVERNIGHT. TUESDAY THROUGH FRIDAY...EXITING WAVE WILL CLIP THE NORTHERN AND CENTRAL MOUNTAINS WITH BRIEF PERIOD OF SNOWFALL ON TUESDAY. THE ECMWF REMAINS A BIT STRONGER WITH THIS WAVE...WHICH WOULD RESULT IN A BIT MORE ACTIVITY ACROSS THE FORECAST AREA. WILL SPLIT THE DIFFERENCE AND KEEP HIGHER POPS CONFINED TO THE NORTHERN AND CENTRAL MOUNTAINS. YET ANOTHER VERY WEAK SYSTEM BRUSHES BY ON WEDNESDAY...BRINGING A SLIGHT CHANCE FOR HIGH MOUNTAIN SNOW SHOWERS...OTHERWISE A DRY PERIOD IN STORE FROM TUESDAY NIGHT THROUGH EARLY FRIDAY. THE GFS AND EC BOTH DRIVE ANOTHER SYSTEM DOWN THE SPINE OF THE ROCKIES TO CLOSE OUT THE WEEK. THIS WOULD BRING ANOTHER GLANCING SHOT OF PRECIPITATION TO THE AREA...GENERALLY CONFINED TO THE NORTHERN ZONES. TEMPERATURES WILL BE MODERATING A BIT THROUGH THE PERIOD...WITH READINGS CLIMBING TO THE PLUS SIDE OF NORMAL AS WE CLOSE OUT THE WEEK. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SATURDAY NIGHT) ISSUED AT 343 AM MDT SAT APR 20 2013 WIDESPREAD RAIN AND SNOW SHOWERS WILL OCCUR THROUGH THIS AFTERNOON...WITH MOUNTAINS FQTLY OBSCD. EXPECT AREAS OF MVFR CIGS AND VSBYS...WITH LOCAL IFR CONDITIONS AS THE SHOWERS PASS THROUGH. SLOW IMPROVEMENT WILL OCCUR FROM WEST TO EAST AFTER 21Z THIS AFTERNOON...ALTHOUGH AREAS NEAR THE DIVIDE WILL CONTINUE TO BE IMPACTED THROUGH 06Z SUNDAY. && .GJT WATCHES/WARNINGS/ADVISORIES... CO...WINTER WEATHER ADVISORY UNTIL MIDNIGHT MDT TONIGHT FOR COZ004- 010-013. UT...NONE. && $$ SHORT TERM...JDC LONG TERM...JOE AVIATION...JDC
AREA FORECAST DISCUSSION
NWS GRAND JUNCTION CO
344 AM MDT SAT APR 20 2013 .SHORT TERM...(TODAY THROUGH SUNDAY) ISSUED AT 343 AM MDT SAT APR 20 2013 TODAY...SHORTWAVE AND ASSOCIATED SFC FRONT MAKING QUICK PROGRESS ACROSS THE GREAT BASIN THIS MORNING AND WILL BE PUSHING EAST ACROSS WESTERN COLORADO TODAY. AREAS OF LIGHT RAIN AND SNOW FALLING ACROSS THE REGION WILL PEAK IN AREAL COVERAGE THIS MORNING AS THE MAIN FORCING ASSOCIATED WITH THE PASSING WAVE ARRIVES. RADAR ECHOES HAVE BEEN ON THE INCREASE THIS MORNING AND MORNING HRRR AND RAP MODELS BOTH INDICATING A FAIRLY ACTIVE START TO THE DAY WITH SNOW LEVELS RUNNING AROUND 6K. BEST ACCUMULATIONS LOOKS TO BE CONFINED TO THE HIGHER ELEVATIONS...WITH THE NORTHERN MOUNTAINS REMAINING FAVORED ATTM...WITH CURRENT ADVISORIES ON TRACK. HAVE BOOSTED POPS AND SHAVED TEMPS A BIT FROM MOS VALUES. TONIGHT...THOUGH DYNAMICAL SUPPORT HAS SHIFTED EAST SNOW WILL CONTINUE ACROSS NW COLORADO WITH FORECAST SOUNDINGS INDICATING A MOIST NW OROGRAPHIC FLOW THROUGH MIDNIGHT. THEN THE FLOW SLACKENS SOMEWHAT AND BACKS TO SW. THE MOIST LAYER ALSO SHRINKS TO BELOW 12KFT FOR LITTLE TO NO ACCUMULATING SNOWFALL. TEMPERATURES STAY NEAR NORMAL NORTH UNDER CLOUD COVER...ABOUT 5 DEGREES BELOW NORMAL FOR THE CENTRAL AND SOUTH UNDER MOSTLY CLEAR SKIES. SUNDAY...WEST WINDS INCREASE AS THE NEXT OPEN WAVE WORKS IN FROM THE NW. THE JET REMAINS ORIENTED NEAR THE CO-WY BORDER EFFECTIVELY KEEPING THE COLD AIR AND DYNAMICS NORTH OF THIS FORECAST AREA. AFTERNOON HEATING AND MARGINAL MOISTURE PRODUCE A SLIVER OF AFTERNOON CAPE MAINLY IN THE NW CO MTNS FOR SCATTERED SNOW SHOWERS. SNOW LEVEL WILL BE AROUND 8KFT NORTH TO 9KFT CENTRAL. .LONG TERM...(SUNDAY NIGHT THROUGH FRIDAY) ISSUED AT 343 AM MDT SAT APR 20 2013 SUNDAY NIGHT-MONDAY NIGHT...ENHANCING ENERGY DEVELOPS A TROUGH AND BEGINS TO PUSH THE JET AND ASSOCIATED COLD FRONT NW-SE THROUGH THE REGION. THE BEST DYNAMICAL SUPPORT SHIFTS EAST OF THE CONTINENTAL DIVIDE WITH SNOW ACCUMULATIONS NOW LOOKING MEAGER EXCEPT ALONG THE COLORADO SPINE WHERE A CONVECTIVE COMPONENT MAY PRODUCE LOCALIZED ENHANCED SNOW ACCUMULATIONS. BREEZY TO WINDY CONDITIONS CONTINUE ON MONDAY AS THE COLD FRONT WORKS THROUGH THE REGION WITH A COOLER DRIER AIR MASS WORKING IN OVERNIGHT. TUESDAY THROUGH FRIDAY...EXITING WAVE WILL CLIP THE NORTHERN AND CENTRAL MOUNTAINS WITH BRIEF PERIOD OF SNOWFALL ON TUESDAY. THE ECMWF REMAINS A BIT STRONGER WITH THIS WAVE...WHICH WOULD RESULT IN A BIT MORE ACTIVITY ACROSS THE FORECAST AREA. WILL SPLIT THE DIFFERENCE AND KEEP HIGHER POPS CONFINED TO THE NORTHERN AND CENTRAL MOUNTAINS. YET ANOTHER VERY WEAK SYSTEM BRUSHES BY ON WEDNESDAY...BRINGING A SLIGHT CHANCE FOR HIGH MOUNTAIN SNOW SHOWERS...OTHERWISE A DRY PERIOD IN STORE FROM TUESDAY NIGHT THROUGH EARLY FRIDAY. THE GFS AND EC BOTH DRIVE ANOTHER SYSTEM DOWN THE SPINE OF THE ROCKIES TO CLOSE OUT THE WEEK. THIS WOULD BRING ANOTHER GLANCING SHOT OF PRECIPITATION TO THE AREA...GENERALLY CONFINED TO THE NORTHERN ZONES. TEMPERATURES WILL BE MODERATING A BIT THROUGH THE PERIOD...WITH READINGS CLIMBING TO THE PLUS SIDE OF NORMAL AS WE CLOSE OUT THE WEEK. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT) ISSUED AT 343 AM MDT SAT APR 20 2013 WIDESPREAD RAIN AND SNOW SHOWERS WILL OCCUR THROUGH THIS AFTERNOON...WITH MOUNTAINS FQTLY OBSCD. EXPECT AREAS OF MVFR CIGS AND VSBYS...WITH LOCAL IFR CONDITIONS AS THE SHOWERS PASS THROUGH. SLOW IMPROVEMENT WILL OCCUR FROM WEST TO EAST AFTER 21Z THIS AFTERNOON...ALTHOUGH AREAS NEAR THE DIVIDE WILL CONTINUE TO BE IMPACTED THROUGH 06Z SUNDAY. && .GJT WATCHES/WARNINGS/ADVISORIES... CO...WINTER WEATHER ADVISORY UNTIL MIDNIGHT MDT TONIGHT FOR COZ004- 010-013. UT...NONE. && $$ SHORT TERM...JDC LONG TERM...JOE AVIATION...JDC
AREA FORECAST DISCUSSION
NWS MIAMI FL
947 AM EDT SAT APR 20 2013 .UPDATE... SHOWERS AND THUNDERSTORMS OVER THE ATLANTIC WATERS HAVE DEVELOPED THIS MORNING DUE TO THE CONVERGENCE OF SE FLOW OVER THE BAHAMAS AND MORE SOUTHERLY FLOW OVER SOUTH FLORIDA. THE 12Z SOUNDING FROM THIS MORNING SHOWS A CAP AROUND 650 MB ASSOCIATED WITH THE SUBTROPICAL HIGH PRESSURE OVER THE ATLANTIC AND THE GULF. 500 MB TEMPERATURES ARE AROUND -6C AND ARE NOT EXPECTED TO COOL BEYOND -7C THIS AFTERNOON. HOWEVER, THE INFLUENCE OF A COLD FRONT MOVING SOUTHWARD IS EXPECTED TO INTERACT WITH A WEAK EAST COAST SEA BREEZE TO TRIGGER SHOWERS AND THUNDERSTORMS, ESPECIALLY IN PALM BEACH AND BROWARD COUNTIES. SOME STORMS CAN ALSO EXTEND INTO MIAMI-DADE. FOR THE WEST COAST THERE IS ONLY A SMALL CHANCE OF THUNDERSTORMS, SINCE MOST OF THE SURFACE TROUGH IS ALIGNED FROM NORTHEAST TO SOUTHWEST OVER THE ATLANTIC WATERS. AS MENTIONED IN THE PREVIOUS DISCUSSION THE UPPER LEVEL TEMPERATURES ARE FORECAST TO COOL ON SUNDAY ALLOWING FOR A GREATER CHANCE OF THUNDERSTORMS THAN TODAY. FOR TODAY THE HIGHEST POPS ARE STILL INCLUDED FOR PALM BEACH AND BROWARD. && .PREV DISCUSSION... /ISSUED 725 AM EDT SAT APR 20 2013/ AVIATION... MOSTLY VFR CONDITIONS WILL OCCUR EARLY IN THE FORECAST ALTHOUGH THERE COULD BE A BRIEF MVFR CIG AS A FEW SHOWERS MOVE ACROSS SOUTH FLORIDA. SCATTERED TO NUMEROUS SHOWERS AND THUNDERSTORMS ARE EXPECTED TO DEVELOP BY THIS AFTERNOON AHEAD OF A WEAKENING COLD FRONT THAT WILL SAG ACROSS THE REGION. THE HRRR INDICATES CONVECTION TO BEGIN DEVELOPING IN EARNEST BETWEEN 18-20Z WITH THE STEERING FLOW TAKING THE STORMS TO THE EAST COAST. THEREFORE, HAVE LEFT TEMPO 18-22Z FOR ALL EAST TERMINALS WITH SOME OF THE ACTIVITY POSSIBLY PERSISTING BEYOND THIS TIME FRAME. SURFACE WINDS ARE QUESTIONABLE WITH A SLOW MOVING FRONTAL BOUNDARY BUT GENERALLY SSW-SSE AHEAD OF THE FRONT AND NE BEHIND THE FRONT. && .PRELIMINARY POINT TEMPS/POPS... WEST PALM BEACH 85 71 83 72 / 60 40 60 40 FORT LAUDERDALE 85 75 84 74 / 50 30 60 40 MIAMI 87 73 85 73 / 40 30 50 40 NAPLES 86 69 86 69 / 40 20 40 40 && .MFL WATCHES/WARNINGS/ADVISORIES... FL...NONE. AM...NONE. GM...NONE. && $$ DISCUSSION/MARINE/FIRE...71/JE AVIATION/RADAR...10/CD
AREA FORECAST DISCUSSION
NWS MIAMI FL
725 AM EDT SAT APR 20 2013 .AVIATION... MOSTLY VFR CONDITIONS WILL OCCUR EARLY IN THE FORECAST ALTHOUGH THERE COULD BE A BRIEF MVFR CIG AS A FEW SHOWERS MOVE ACROSS SOUTH FLORIDA. SCATTERED TO NUMEROUS SHOWERS AND THUNDERSTORMS ARE EXPECTED TO DEVELOP BY THIS AFTERNOON AHEAD OF A WEAKENING COLD FRONT THAT WILL SAG ACROSS THE REGION. THE HRRR INDICATES CONVECTION TO BEGIN DEVELOPING IN EARNEST BETWEEN 18-20Z WITH THE STEERING FLOW TAKING THE STORMS TO THE EAST COAST. THEREFORE, HAVE LEFT TEMPO 18-22Z FOR ALL EAST TERMINALS WITH SOME OF THE ACTIVITY POSSIBLY PERSISTING BEYOND THIS TIME FRAME. SURFACE WINDS ARE QUESTIONABLE WITH A SLOW MOVING FRONTAL BOUNDARY BUT GENERALLY SSW-SSE AHEAD OF THE FRONT AND NE BEHIND THE FRONT. && .PRELIMINARY POINT TEMPS/POPS... WEST PALM BEACH 85 71 83 72 / 60 40 60 40 FORT LAUDERDALE 85 75 84 74 / 50 30 60 40 MIAMI 87 73 85 73 / 40 30 50 40 NAPLES 86 69 86 69 / 40 20 40 40 && .MFL WATCHES/WARNINGS/ADVISORIES... FL...NONE. AM...NONE. GM...NONE. && $$
AREA FORECAST DISCUSSION...UPDATED
NWS MELBOURNE FL
427 AM EDT SAT APR 20 2013 .DISCUSSION... TODAY... A THIN BAND OF SHOWERS ACCOMPANYING A COLD FRONT...STRETCHING FROM DAYTONA BEACH TO TAMPA...WILL SLOWLY CROSS EC FL AND SETTLE OVER SOUTH FLORIDA BY EVE. SOME HEATING SHOULD OCCUR SOUTH OF ORLANDO PRIOR TO FRONTAL PASSAGE THIS MORNING AND EARLY AFTERNOON WHICH SHOULD PRODUCE A BETTER CHANCE FOR DEEP CONVECTION (THUNDER). WILL HOLD ONTO SCATTERED SHOWERS ACROSS THE NORTH EVEN AFTER THE BAND MOVES THROUGH AS A MID LEVEL DISTURBANCE CROSSES NORTH FLORIDA LATER TODAY AND THIS EVENING. MOS GUIDANCE POPS LOOK TOO HIGH THOUGH AND HAVE DRAWN 50 POPS MOST AREAS. IN FACT...THINK COVERAGE SHOULD BE A LITTLE HIGHER ACROSS THE SOUTHERN 1/3 OF FA...WITH 60 POPS. TEMPERATURES ARE TRICKY TODAY ESP ACROSS THE NORTH. IN SOME PLACES THE HIGH MAY OCCUR EARLY THIS MORNING JUST BEFORE FRONTAL PASSAGE. NORTH WINDS 15 MPH AND WIDESPREAD LOW CLOUDS BEHIND THE FRONT WILL LIMIT SFC HEATING. FOR EXAMPLE...DAYTONA BEACH WILL LIKELY FALL INTO THE 60S BEHIND THE FRONT AND NOT CLIMB BACK OUT. ON THE OTHER HAND...MAX TEMPS SHOULD REACH THE MID 80S AROUND LAKE OKEECHOBEE/ MARTIN COUNTY. TONIGHT... FRONT IS FORECAST TO HANG UP JUST TO OUR SOUTH BUT CONSIDERABLE MOISTURE WILL REMAIN OVER THE AREA. THERE MAY BE SOME RESIDUAL SHOWERS ACROSS THE NORTH ASSOCD WITH DEPARTING MID LEVEL SHORTWAVE AND UPPER JET. SO WILL HOLD ONTO 30 POPS FOR SHOWERS IN LAKE AND VOLUSIA IN THE EVENING. PERSISTENT ONSHORE FLOW WILL REQUIRE A 20 POP ALONG THE COAST MAINLY FOR POTENTIAL FOR A FEW BANDS TO SET UP AND CROSS THE COAST. SUN-MON... UNSEASONABLE WET WX PATTERN FOR CENTRAL FL...GIVEN THAT APR IS CLIMATOLOGICALLY THE DRIEST MONTH OF THE YEAR. A COLD FRONT EXTENDING FROM THE MID ATLC TO THE YUCATAN PENINSULA WILL GRIND TO A HALT AGAINST A LARGE HI PRES RIDGE OVER THE WRN ATLC. DEEP MOISTURE POOLING WITHIN THE FRONTAL TROF WILL MERGE WITH RELATIVELY HIGH MOISTURE OVER THE WRN ATLC/NW CARIB...ALLOWING PWAT VALUES TO REACH AS HIGH AS 1.5"-1.7" ALONG THE TREASURE COAST. LOWER PWATS (1.3"-1.5") ALONG AND N OF THE I-4 CORRIDOR AS POST FRONTAL DRY AIR WORKS ITS WAY DOWN THE PENINSULA. H30-H20 LIFTING JET OVER THE ERN CONUS/NRN GOMEX WILL GENERATE STRONG UPR LVL DIVERGENCE ACRS THE REGION. UPSTREAM MID LVL ENERGY IS RATHER SPARSE AS THE LATEST RUC ANALYSIS SHOWS LITTLE IN THE WAY OF ORGANIZED H85-H50 VORTICITY OVER THE SRN TIER STATES. OMEGA LIFT ALONG THE FRONTAL BOUNDARY...HOWEVER...SHOULD PROVIDE SUFFICIENT MID LVL SUPPORT TO KEEP POPS AOA 50PCT. WILL GO WITH 50 POPS ALONG AND N OF I-4...60 POPS TO THE S DUE TO DEEPER AND MORE ABUNDANT MOISTURE. WILL KEEP THUNDER IN THE SLGT CHC CATEGORY TUE TO THE LACK OF LOW/MID LVL INSTABILITY. NE BREEZE WILL PREVAIL...ALLOWING OCEAN MODIFIED AIR TO ADVECT ACRS THE CENTRAL PENINSULA. MAX TEMPS IN THE U70S/L80S ALONG THE COAST... L/M80S INTERIOR. MIN TEMPS M/U60S ALONG THE COAST...L/M60S INTERIOR. TUE-FRI... PRECIP TO LINGER INTO TUE AS MOISTURE CONTINUES TO POOL WITHIN THE WEAKENING FRONTAL BOUNDARY. GFS/ECMWF MODELS IN GOOD AGREEMENT WITH THE DVLPMNT OF A WEAK SPOT LOW OFF THE CAROLINA COAST BY DAYBREAK TUE. THE NEWLY DVLPD LOW WILL PROVIDE THE TORQUE NECESSARY TO CRANK THE FRONTAL REMNANTS INTO S FL WHILE HELPING DRIER CONTINENTAL AIR TO FILTER INTO CENTRAL FL. MODELS HAVE BACKED OFF THEIR PREVIOUS SOLUTION OF BRINGING A NEW COLD FRONT INTO CENTRAL FL LATE WED INTO THU. GFS STALLS IT OVER THE PANHANDLE WHILE ECMWF INDICATES ITS SRN EXTENSION WILL DISSIPATE AS IT PUSHES DOWN THE PENINSULA. INCLINED TO GO WITH THE DRIER SOLUTION GIVEN THIS TIME OF YEAR IS THE PEAK OF THE DRY SEASON. WILL KEEP SMALL POPS IN THE FCST FOR THU TO ACCOUNT FOR THE PRESENCE OF THE FRONT...POPS TOO LOW TO MENTION THRU THE REMAINDER OF THE FCST. NO INDICATIONS OF UNUSUALLY HIGH OR LOW TEMPS THRU THE UPCOMING WEEK...READINGS SHOULD BE WITHIN ABOUT 5F DEG OF CLIMO AVGS. && .AVIATION... FRONT WILL PRESS E/SE AND CROSS LEE/DAB/SFB/MCO BY 8 AM...FPR/SUA BY 18Z. THIN BAND OF SHRA WILL ACCOMPANY THE FRONT WITH SCATTERED SHRA/ISOLATED TSRA POSSIBLE AHEAD OF THE FRONT WHERE SFC HEATING CAN OCCUR SOUTH OF MCO. PRIMARY IMPACT WILL BE PREVAILING MVFR CIGS BEHIND THE FRONT WITH TEMPO IFR CIGS POSS ESP THROUGH 13Z MCO NORTHWARD. THERE SHOULD BE A PERIOD OF VFR CIGS DURING THE AFTN AND EARLY EVE ACROSS MANY TERMINALS BUT EXPECT PREVAILING MVFR CIGS TO RETURN AFT 00Z. && .MARINE... TODAY...AS EXPECTED THE SOUTHERLY FLOW HAS WEAKENED A BIT AS PRES GRAD BECOMES BAGGY ASSOCD WITH FRONTAL ZONE. BUT A SURGE OF NORTH WINDS WILL OVERSPREAD THE NORTHERN WATERS EARLY THIS MORNING BEHIND THE FRONT SO HAVE RAISED SMALL CRAFT ADVISORY FOR THE OFFSHORE VOLUSIA WATERS FOR 20 KNOTS. CLOSER TO THE COAST AND TO THE SOUTH EXPECT 15-20 KNOTS SO WILL HEADLINE CAUTION. BUT CONDITIONS WILL BE QUITE UNFAVORABLE ESPECIALLY IN THE GULF STREAM. IN ADDITION...A BAND OF SHOWERS WILL PUSH OFFSHORE ASSOCD WITH THE FRONT WITH A FEW STORMS PUSHING OFFSHORE BREVARD TO THE TREASURE COAST. TONIGHT...WEAK FRONTAL TROUGH IS FORECAST TO STALL JUST TO THE SOUTH AND EAST OF THE OUR COASTAL WATERS. THE NORTH TO NORTHEAST PRES GRAD WILL SUPPORT 15 KNOTS SO WILL LIKELY NEED A CAUTION IN THE GULF STREAM WITH SEAS UP TO 6 FT. SUN-SUN NIGHT...A STRONG HIGH PRES RIDGE WILL BUILD ACRS THE ERN CONUS...GENERATING A MODERATE TO FRESH NE BREEZE. WINDS BCMG A LIGHT TO GENTLE SE BREEZE S OF SEBASTIAN INLET AFT SUNSET AS AN INVERTED TROF BEGINS TO FORM OVER S FL ALONG A STALLED FRONTAL BNDRY. SCT/NMRS SHRAS AND ISOLD TSRAS. SEAS BUILDING TO 6-8FT N OF SEBASTIAN INLET...4-6FT TO THE SOUTH. MON-MON NIGHT...THE HIGH PRES RIDGE WILL LIFT INTO THE CANADIAN MARITIMES...TRAILING ITS RIDGE AXIS DOWN THE ERN CONUS AND INTO THE LWR MS VALLEY. A WEAK LOW WILL DVLP OFF THE CAROLINA COAST AND INTERACT WITH THE RIDGE...GENERATING A MODERATE TO FRESH NE BREEZE N OF SEBASTIAN INLET. S OF THE INLET PGRAD WILL BE WEAKER DUE TO THE FURTHER PROXIMITY TO THE DLVPG LOW...GENTLE TO MODERATE E/NE BREEZE WILL RESULT. SEAS 6-8FT N OF SEBASTIAN INLET...4-6FT TO THE SOUTH. TUE-TUE NIGHT...WINDS WILL DIMINISH AS THE LOW LIFTS UP THE ERN SEABOARD...BCMG A GENTLE TO MODERATE NE BREEZE AREAWIDE BY LATE AFTN. PERSISTENT E/NERLY FETCH OVER THE WRN ATLC WILL PUSH A SWELL INTO THE E FL COAST...KEEPING SEAS 4-6FT NEARSHORE AND 5-7FT OFFSHORE. WED-WED NIGHT...A HIGH PRES RIDGE WILL BUILD OFF THE SE COAST... GENERATING A LIGHT TO GENTLE E/SE BREEZE. COMBINED SEAS 3-4FT NEARSHORE...4-5FT OFFSHORE. && .PRELIMINARY POINT TEMPS/POPS... DAB 67 63 76 67 / 50 30 50 40 MCO 75 62 81 65 / 50 30 50 40 MLB 76 67 78 70 / 50 20 60 50 VRB 80 68 79 69 / 50 20 60 50 LEE 73 60 79 65 / 50 30 50 40 SFB 73 61 79 66 / 50 30 50 40 ORL 76 62 81 66 / 50 30 50 40 FPR 81 68 79 69 / 50 20 60 50 && .MLB WATCHES/WARNINGS/ADVISORIES... FL...NONE. AM...SMALL CRAFT ADVISORY UNTIL 2 PM EDT THIS AFTERNOON FOR WATERS FROM FLAGLER BEACH TO VOLUSIA BREVARD COUNTY LINE 20 TO 60 NM OFFSHORE. && $$ SHORT TERM/AVIATION...KELLY LONG TERM/IMPACT WX...BRAGAW
AREA FORECAST DISCUSSION
NWS MELBOURNE FL
411 AM EDT SAT APR 20 2013 .DISCUSSION... TODAY...A THIN BAND OF SHOWERS ACCOMPANYING A COLD FRONT... STRETCHING FROM DAYTONA BEACH TO TAMPA...WILL SLOWLY CROSS EC FL AND SETTLE OVER SOUTH FLORIDA BY EVE. SOME HEATING SHOULD OCCUR SOUTH OF ORLANDO PRIOR TO FRONTAL PASSAGE THIS MORNING AND EARLY AFTERNOON WHICH SHOULD PRODUCE A BETTER CHANCE FOR DEEP CONVECTION (THUNDER). WILL HOLD ONTO SCATTERED SHOWERS ACROSS THE NORTH EVEN AFTER THE BAND MOVES THROUGH AS A MID LEVEL DISTURBANCE CROSSES NORTH FLORIDA LATER TODAY AND THIS EVENING. MOS GUIDANCE POPS LOOK TOO HIGH THOUGH AND HAVE DRAWN 50 POPS MOST AREAS. IN FACT...THINK COVERAGE SHOULD BE A LITTLE HIGHER ACROSS THE SOUTHERN 1/3 OF FA...WITH 60 POPS. TEMPERATURES ARE TRICKY TODAY ESP ACROSS THE NORTH. IN SOME PLACES THE HIGH MAY OCCUR EARLY THIS MORNING JUST BEFORE FRONTAL PASSAGE. NORTH WINDS 15 MPH AND WIDESPREAD LOW CLOUDS BEHIND THE FRONT WILL LIMIT SFC HEATING. FOR EXAMPLE...DAYTONA BEACH WILL LIKELY FALL INTO THE 60S BEHIND THE FRONT AND NOT CLIMB BACK OUT. ON THE OTHER HAND...MAX TEMPS SHOULD REACH THE MID 80S AROUND LAKE OKEECHOBEE/ MARTIN COUNTY. TONIGHT...FRONT IS FORECAST TO HANG UP JUST TO OUR SOUTH BUT CONSIDERABLE MOISTURE WILL REMAIN OVER THE AREA. THERE MAY BE SOME RESIDUAL SHOWERS ACROSS THE NORTH ASSOCD WITH DEPARTING MID LEVEL SHORTWAVE AND UPPER JET. SO WILL HOLD ONTO 30 POPS FOR SHOWERS IN LAKE AND VOLUSIA IN THE EVENING. PERSISTENT ONSHORE FLOW WILL REQUIRE A 20 POP ALONG THE COAST MAINLY FOR POTENTIAL FOR A FEW BANDS TO SET UP AND CROSS THE COAST. SUN-MON... UNSEASONABLE WET WX PATTERN FOR CENTRAL FL...GIVEN THAT APR IS CLIMATOLOGICALLY THE DRIEST MONTH OF THE YEAR. A COLD FRONT EXTENDING FROM THE MID ATLC TO THE YUCATAN PENINSULA WILL GRIND TO A HALT AGAINST A LARGE HI PRES RIDGE OVER THE WRN ATLC. DEEP MOISTURE POOLING WITHIN THE FRONTAL TROF WILL MERGE WITH RELATIVELY HIGH MOISTURE OVER THE WRN ATLC/NW CARIB...ALLOWING PWAT VALUES TO REACH AS HIGH AS 1.5"-1.7" ALONG THE TREASURE COAST. LOWER PWATS (1.3"-1.5") ALONG AND N OF THE I-4 CORRIDOR AS POST FRONTAL DRY AIR WORKS ITS WAY DOWN THE PENINSULA. H30-H20 LIFTING JET OVER THE ERN CONUS/NRN GOMEX WILL GENERATE STRONG UPR LVL DIVERGENCE ACRS THE REGION. UPSTREAM MID LVL ENERGY IS RATHER SPARSE AS THE LATEST RUC ANALYSIS SHOWS LITTLE IN THE WAY OF ORGANIZED H85-H50 VORTICITY OVER THE SRN TIER STATES. OMEGA LIFT ALONG THE FRONTAL BOUNDARY...HOWEVER...SHOULD PROVIDE SUFFICIENT MID LVL SUPPORT TO KEEP POPS AOA 50PCT. WILL GO WITH 50 POPS ALONG AND N OF I-4...60 POPS TO THE S DUE TO DEEPER AND MORE ABUNDANT MOISTURE. WILL KEEP THUNDER IN THE SLGT CHC CATEGORY TUE TO THE LACK OF LOW/MID LVL INSTABILITY. NE BREEZE WILL PREVAIL...ALLOWING OCEAN MODIFIED AIR TO ADVECT ACRS THE CENTRAL PENINSULA. MAX TEMPS IN THE U70S/L80S ALONG THE COAST... L/M80S INTERIOR. MIN TEMPS M/U60S ALONG THE COAST...L/M60S INTERIOR. TUE-FRI... UPDATE TO FOLLOW. && .AVIATION... FRONT WILL PRESS E/SE AND CROSS LEE/DAB/SFB/MCO BY 8 AM...FPR/SUA BY 18Z. THIN BAND OF SHRA WILL ACCOMPANY THE FRONT WITH SCATTERED SHRA/ISOLATED TSRA POSSIBLE AHEAD OF THE FRONT WHERE SFC HEATING CAN OCCUR SOUTH OF MCO. PRIMARY IMPACT WILL BE PREVAILING MVFR CIGS BEHIND THE FRONT WITH TEMPO IFR CIGS POSS ESP THROUGH 13Z MCO NORTHWARD. THERE SHOULD BE A PERIOD OF VFR CIGS DURING THE AFTN AND EARLY EVE ACROSS MANY TERMINALS BUT EXPECT PREVAILING MVFR CIGS TO RETURN AFT 00Z. && .MARINE... TODAY...AS EXPECTED THE SOUTHERLY FLOW HAS WEAKENED A BIT AS PRES GRAD BECOMES BAGGY ASSOCD WITH FRONTAL ZONE. BUT A SURGE OF NORTH WINDS WILL OVERSPREAD THE NORTHERN WATERS EARLY THIS MORNING BEHIND THE FRONT SO HAVE RAISED SMALL CRAFT ADVISORY FOR THE OFFSHORE VOLUSIA WATERS FOR 20 KNOTS. CLOSER TO THE COAST AND TO THE SOUTH EXPECT 15-20 KNOTS SO WILL HEADLINE CAUTION. BUT CONDITIONS WILL BE QUITE UNFAVORABLE ESPECIALLY IN THE GULF STREAM. IN ADDITION...A BAND OF SHOWERS WILL PUSH OFFSHORE ASSOCD WITH THE FRONT WITH A FEW STORMS PUSHING OFFSHORE BREVARD TO THE TREASURE COAST. TONIGHT...WEAK FRONTAL TROUGH IS FORECAST TO STALL JUST TO THE SOUTH AND EAST OF THE OUR COASTAL WATERS. THE NORTH TO NORTHEAST PRES GRAD WILL SUPPORT 15 KNOTS SO WILL LIKELY NEED A CAUTION IN THE GULF STREAM WITH SEAS UP TO 6 FT. SUN-SUN NIGHT...A STRONG HIGH PRES RIDGE WILL BUILD ACRS THE ERN CONUS...GENERATING A MODERATE TO FRESH NE BREEZE. WINDS BCMG A LIGHT TO GENTLE SE BREEZE S OF SEBASTIAN INLET AFT SUNSET AS AN INVERTED TROF BEGINS TO FORM OVER S FL ALONG A STALLED FRONTAL BNDRY. SCT/NMRS SHRAS AND ISOLD TSRAS. SEAS BUILDING TO 6-8FT N OF SEBASTIAN INLET...4-6FT TO THE SOUTH. MON-MON NIGHT...THE HIGH PRES RIDGE WILL LIFT INTO THE CANADIAN MARITIMES...TRAILING ITS RIDGE AXIS DOWN THE ERN CONUS AND INTO THE LWR MS VALLEY. A WEAK LOW WILL DVLP OFF THE CAROLINA COAST AND INTERACT WITH THE RIDGE...GENERATING A MODERATE TO FRESH NE BREEZE N OF SEBASTIAN INLET. S OF THE INLET PGRAD WILL BE WEAKER DUE TO THE FURTHER PROXIMITY TO THE DLVPG LOW...GENTLE TO MODERATE E/NE BREEZE WILL RESULT. SEAS 6-8FT N OF SEBASTIAN INLET...4-6FT TO THE SOUTH. TUE-TUE NIGHT...WINDS WILL DIMINISH AS THE LOW LIFTS UP THE ERN SEABOARD...BCMG A GENTLE TO MODERATE NE BREEZE AREAWIDE BY LATE AFTN. PERSISTENT E/NERLY FETCH OVER THE WRN ATLC WILL PUSH A SWELL INTO THE E FL COAST...KEEPING SEAS 4-6FT NEARSHORE AND 5-7FT OFFSHORE. WED-WED NIGHT...A HIGH PRES RIDGE WILL BUILD OFF THE SE COAST... GENERATING A LIGHT TO GENTLE E/SE BREEZE. COMBINED SEAS 3-4FT NEARSHORE...4-5FT OFFSHORE. && .PRELIMINARY POINT TEMPS/POPS... DAB 67 63 76 67 / 50 30 50 40 MCO 75 62 81 65 / 50 30 50 40 MLB 76 67 78 70 / 50 20 60 50 VRB 80 68 79 69 / 50 20 60 50 LEE 73 60 79 65 / 50 30 50 40 SFB 73 61 79 66 / 50 30 50 40 ORL 76 62 81 66 / 50 30 50 40 FPR 81 68 79 69 / 50 20 60 50 && .MLB WATCHES/WARNINGS/ADVISORIES... FL...NONE. AM...SMALL CRAFT ADVISORY UNTIL 2 PM EDT THIS AFTERNOON FOR WATERS FROM FLAGLER BEACH TO VOLUSIA BREVARD COUNTY LINE 20 TO 60 NM OFFSHORE. && $$ SHORT TERM...KELLY LONG TERM....BRAGAW
AREA FORECAST DISCUSSION
NWS NORTHERN INDIANA
558 AM EDT SAT APR 20 2013 .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 352 AM EDT SAT APR 20 2013 SCATTERED SNOW SHOWERS CONTINUE ACROSS THE CWA AT PRESS TIME...AIDED BY PERSISTENT MOIST CYCLONIC FLOW ASSOCIATED WITH PASSING MIDLEVEL TROUGH AXIS. HI-RES FORECAST SOUNDINGS ALSO SHOW BOUNDARY LAYER HAS REMAINED WELL MIXED THROUGH THE OVERNIGHT HOURS...FURTHER SUPPORTING CONVECTIVE SNOW SHOWERS. QUESTION WILL BE WHETHER OR NOT ACTIVITY CAN PERSIST BEYOND 12Z. A FEW PREVIOUS RAP MODEL RUNS SUGGESTED ISOLATED RAIN/SNOW SHOWERS PERSISTING FOR MUCH OF THE MORNING AS ONE LAST RIBBON OF SHEAR VORTICITY ROTATES THROUGH THE AREA. HOWEVER...MIDLEVEL HEIGHTS WILL BE CLIMBING QUICKLY BY LATER THIS MORNING AND NAM BUFR DATA SHOWS LOWER TROPOSPHERIC DRY AIR INCREASING AS WELL AS A STRENGTHENING SUBSIDENCE INVERSION. THEREFORE EXPECT LITTLE MORE THAN ISOLATED FLURRIES AFTER 12Z WITH INCREASINGLY ANTICYCLONIC FLOW BRINGING DRY CONDITIONS EVERYWHERE BY MIDDAY. THERMAL TROUGH WILL BE SHIFTING EAST BY THE AFTERNOON BUT 850MB TEMPS STILL EXPECTED TO BE AROUND -8C DURING PEAK HEATING. MIXING THIS TO THE SURFACE ONLY GIVES HIGHS IN THE LOW 40S. WILL LIKELY BE ENOUGH RESIDUAL BOUNDARY LAYER MOISTURE TO SUPPORT SOME AFTERNOON STRATOCU BUT EXPECT A FAIR AMOUNT OF INSOLATION TO ADD A DEGREE OR TWO TO THAT. GIVEN YESTERDAYS EXTREME WARM BIAS IN MOS GUIDANCE...WILL NUDGE THE FORECAST TOWARD COOLER RAW TEMPS. HESITANT TO DEVIATE LARGELY THOUGH. THIS IS AN ANOMALOUSLY COLD AIRMASS BUT THERMAL PROFILES WILL BE RECOVERING BY THE AFTERNOON AND DECREASING CLOUDS SHOULD ALLOW HIGHS TO CLIMB A BIT WARMER THAN YESTERDAY...GENERALLY LOW TO MID 40S. DIFFICULT MIN TEMP FORECAST TONIGHT. SURFACE ANTICYCLONE WILL BE OVERHEAD DURING THE EVENING HOURS BUT MODELS SUGGEST LIGHT SOUTHEAST WINDS DEVELOPING BY EARLY SUNDAY MORNING ALONG WITH PERHAPS SOME INCREASING MID/UPPER LEVEL CLOUDS. CURRENT TIMING INDICATES THESE CONDITIONS WILL BE TOO LATE TO PREVENT SUBSTANTIAL RADIATIVE LOSSES THOUGH AND HAVE THEREFORE PUSHED TEMPS DOWN A BIT. EXPECT GENERALLY MID TO UPPER 20S BUT A FEW ISOLATED LOWER 20S ARE POSSIBLE ACROSS THE NORTH. && .LONG TERM...(SUNDAY THROUGH FRIDAY) ISSUED AT 352 AM EDT SAT APR 20 2013 MODELS SUGGEST PERSISTENT PATTERN WITH A CONTINUATION OF A SERIES OF SHRTWVS DIGGING SE FROM WRN CANADA INTO THE PLAINS AND THEN LIFTING OUT TO THE NE ACROSS THE GRTLKS RESULTING IN PERIODIC BOUTS OF INCLEMENT WX WITH TEMPS GENERALLY AOB NORMAL. HIGH PRESSURE OVER THE NRN PLAINS THIS MORNING IS EXPECTED TO MOVE TO THE ERN GRTLKS AND NEW ENGLAND BY SUNDAY AND THEN SLOWLY EAST INTO THE WRN ATLANTIC MONDAY AS NEXT SHRTWV DIGGING INTO THE PLAINS AMPLIFIES THE FLOW ALOFT. THIS SHOULD RESULT IN FAIR WX WITH A WARMING TREND SUNDAY-MONDAY. ANOTHER STRENGTHENING LOW PRESSURE SYSTEM IS EXPECTED TO LIFT NE FROM THE SRN PLAINS MONDAY ACROSS THE WRN GRTLKS TUE-TUE NGT RESULTING IN A PERIOD OF SHOWERS AND PSBLY A FEW TSTMS IN THIS TIMEFRAME. GENERALLY DRY AND COOLER WX SHOULD FOLLOW IN THE WAKE OF THIS SYSTEM WED-THU... THOUGH DID MENTION A SLIGHT CHC OF SHOWERS DURING THE DAYS AS LONGWAVE TROF MOVES SLOWLY EAST ACROSS THE GRTLKS. DRY WX WITH WARMER TEMPS EXPECTED FRI AS SWLY FLOW DVLPS ACROSS OUR AREA ONCE AGAIN AHEAD OF NEXT SHRTWV/CDFNT MOVG INTO THE PLAINS. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SUNDAY MORNING) ISSUED AT 557 AM EDT SAT APR 20 2013 SNOW SHOWERS ARE GRADUALLY TAPERING OFF AS MIDLEVEL TROUGH AXIS LIFTS NORTHEAST AND SUBSIDENCE BUILDS ACROSS THE REGION. A FEW BRIEF PERIODS OF MVFR CONDITIONS REMAIN POSSIBLE OVER THE NEXT FEW HOURS THOUGH. STRATOCU WILL GRADUALLY CLEAR OUT OVER THE COURSE OF THE DAY AS DRIER AIR ADVECTS INTO THE REGION. DEEP MIXING HEIGHTS WILL KEEP CEILINGS WELL INTO VFR CATEGORY REGARDLESS. WEAKENING GRADIENT WILL ALSO BRING DECREASING WINDS THROUGH THE TAF PERIOD. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...NONE. MI...NONE. OH...NONE. LM...SMALL CRAFT ADVISORY UNTIL 5 PM EDT THIS AFTERNOON FOR LMZ043- 046. && $$ SHORT TERM...AGD LONG TERM...JT AVIATION...AGD
AREA FORECAST DISCUSSION
NWS NORTHERN INDIANA
353 AM EDT SAT APR 20 2013 .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 352 AM EDT SAT APR 20 2013 SCATTERED SNOW SHOWERS CONTINUE ACROSS THE CWA AT PRESS TIME...AIDED BY PERSISTENT MOIST CYCLONIC FLOW ASSOCIATED WITH PASSING MIDLEVEL TROUGH AXIS. HI-RES FORECAST SOUNDINGS ALSO SHOW BOUNDARY LAYER HAS REMAINED WELL MIXED THROUGH THE OVERNIGHT HOURS...FURTHER SUPPORTING CONVECTIVE SNOW SHOWERS. QUESTION WILL BE WHETHER OR NOT ACTIVITY CAN PERSIST BEYOND 12Z. A FEW PREVIOUS RAP MODEL RUNS SUGGESTED ISOLATED RAIN/SNOW SHOWERS PERSISTING FOR MUCH OF THE MORNING AS ONE LAST RIBBON OF SHEAR VORTICITY ROTATES THROUGH THE AREA. HOWEVER...MIDLEVEL HEIGHTS WILL BE CLIMBING QUICKLY BY LATER THIS MORNING AND NAM BUFR DATA SHOWS LOWER TROPOSPHERIC DRY AIR INCREASING AS WELL AS A STRENGTHENING SUBSIDENCE INVERSION. THEREFORE EXPECT LITTLE MORE THAN ISOLATED FLURRIES AFTER 12Z WITH INCREASINGLY ANTICYCLONIC FLOW BRINGING DRY CONDITIONS EVERYWHERE BY MIDDAY. THERMAL TROUGH WILL BE SHIFTING EAST BY THE AFTERNOON BUT 850MB TEMPS STILL EXPECTED TO BE AROUND -8C DURING PEAK HEATING. MIXING THIS TO THE SURFACE ONLY GIVES HIGHS IN THE LOW 40S. WILL LIKELY BE ENOUGH RESIDUAL BOUNDARY LAYER MOISTURE TO SUPPORT SOME AFTERNOON STRATOCU BUT EXPECT A FAIR AMOUNT OF INSOLATION TO ADD A DEGREE OR TWO TO THAT. GIVEN YESTERDAYS EXTREME WARM BIAS IN MOS GUIDANCE...WILL NUDGE THE FORECAST TOWARD COOLER RAW TEMPS. HESITANT TO DEVIATE LARGELY THOUGH. THIS IS AN ANOMALOUSLY COLD AIRMASS BUT THERMAL PROFILES WILL BE RECOVERING BY THE AFTERNOON AND DECREASING CLOUDS SHOULD ALLOW HIGHS TO CLIMB A BIT WARMER THAN YESTERDAY...GENERALLY LOW TO MID 40S. DIFFICULT MIN TEMP FORECAST TONIGHT. SURFACE ANTICYCLONE WILL BE OVERHEAD DURING THE EVENING HOURS BUT MODELS SUGGEST LIGHT SOUTHEAST WINDS DEVELOPING BY EARLY SUNDAY MORNING ALONG WITH PERHAPS SOME INCREASING MID/UPPER LEVEL CLOUDS. CURRENT TIMING INDICATES THESE CONDITIONS WILL BE TOO LATE TO PREVENT SUBSTANTIAL RADIATIVE LOSSES THOUGH AND HAVE THEREFORE PUSHED TEMPS DOWN A BIT. EXPECT GENERALLY MID TO UPPER 20S BUT A FEW ISOLATED LOWER 20S ARE POSSIBLE ACROSS THE NORTH. && .LONG TERM...(SUNDAY THROUGH FRIDAY) ISSUED AT 352 AM EDT SAT APR 20 2013 MODELS SUGGEST PERSISTENT PATTERN WITH A CONTINUATION OF A SERIES OF SHRTWVS DIGGING SE FROM WRN CANADA INTO THE PLAINS AND THEN LIFTING OUT TO THE NE ACROSS THE GRTLKS RESULTING IN PERIODIC BOUTS OF INCLEMENT WX WITH TEMPS GENERALLY AOB NORMAL. HIGH PRESSURE OVER THE NRN PLAINS THIS MORNING IS EXPECTED TO MOVE TO THE ERN GRTLKS AND NEW ENGLAND BY SUNDAY AND THEN SLOWLY EAST INTO THE WRN ATLANTIC MONDAY AS NEXT SHRTWV DIGGING INTO THE PLAINS AMPLIFIES THE FLOW ALOFT. THIS SHOULD RESULT IN FAIR WX WITH A WARMING TREND SUNDAY-MONDAY. ANOTHER STRENGTHENING LOW PRESSURE SYSTEM IS EXPECTED TO LIFT NE FROM THE SRN PLAINS MONDAY ACROSS THE WRN GRTLKS TUE-TUE NGT RESULTING IN A PERIOD OF SHOWERS AND PSBLY A FEW TSTMS IN THIS TIMEFRAME. GENERALLY DRY AND COOLER WX SHOULD FOLLOW IN THE WAKE OF THIS SYSTEM WED-THU... THOUGH DID MENTION A SLIGHT CHC OF SHOWERS DURING THE DAYS AS LONGWAVE TROF MOVES SLOWLY EAST ACROSS THE GRTLKS. DRY WX WITH WARMER TEMPS EXPECTED FRI AS SWLY FLOW DVLPS ACROSS OUR AREA ONCE AGAIN AHEAD OF NEXT SHRTWV/CDFNT MOVG INTO THE PLAINS. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT) ISSUED AT 125 AM EDT SAT APR 20 2013 LOW LEVEL CYCLONIC FLOW AND WELL MIXED BOUNDARY LAYER/STEEP LOW LEVEL LAPSE RATES ARE SUPPORTING SCATTERED SNOW SHOWERS ACROSS THE AREA IN THE WAKE OF DEPARTING LOW PRESSURE SYSTEM. COVERAGE IS TOO LOW TO INCLUDE IN THE TAFS AT THIS TIME BUT BRIEF PERIODS OF MVFR CONDITIONS ARE POSSIBLE THROUGH 12Z. DRY AIR AND SUBSIDENCE WILL INCREASE BY LATER THIS MORNING AS HIGH PRESSURE RETURNS TO THE REGION. THIS WILL RESULT IN VFR CONDITIONS THROUGH THE END OF THE TAF PERIOD. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...NONE. MI...NONE. OH...NONE. LM...SMALL CRAFT ADVISORY UNTIL 5 PM EDT THIS AFTERNOON FOR LMZ043- 046. && $$ SHORT TERM...AGD LONG TERM...JT AVIATION...AGD
AREA FORECAST DISCUSSION
NWS GAYLORD MI
300 AM EDT SAT APR 20 2013 .SYNOPSIS... ISSUED AT 300 AM EDT SAT APR 20 2013 LAKE EFFECT SNOW SHOWERS WILL CONTINUE TO IMPACT NORTHERN MICHIGAN THIS MORNING...TARGETING THE TYPICAL SNOWBELT REGIONS OF EASTERN UPPER AND NORTHWEST LOWER MICHIGAN FOR THE MOST PERSISTENT AND HEAVIEST SNOW SHOWERS. HIGH PRESSURE WILL BEGIN TO SETTLE INTO THE GREAT LAKES REGION THIS AFTERNOON...BRINGING QUIET AND SEASONABLY CHILLY WEATHER TO NORTHERN MICHIGAN THROUGH THE REST OF THE WEEKEND. THE NEXT CHANCE OF RAIN ARRIVES FOR THE BEGINNING OF THE WORK WEEK AS WAVES OF LOW PRESSURE PUSH ACROSS THE REGION. && .SHORT TERM...(TODAY THROUGH TONIGHT) ISSUED AT 300 AM EDT SAT APR 20 2013 WELL...THIS JUST ISN`T RIGHT FOR MID APRIL...COLD AND GUSTY NORTHWEST WINDS...WITH NUMEROUS GROUND WHITENING LAKE INDUCED SNOW SHOWERS TARGETING THE TRADITIONAL SNOW BELTS. CULPRIT BEHIND THIS NONSENSE IS ANOMALOUSLY DEEP TROUGH EXTENDING FROM THE MID MISSISSIPPI VALLEY UP THROUGH JAMES BAY. ATTENDANT BEHEMOTH SURFACE LOW NOW WELL TO OUR NORTHEAST UP ACROSS CENTRAL QUEBEC...WITH SURFACE TROUGH AXIS EXTENDING BACK SOUTHWEST INTO OUR AREA. COMBO OF DEEP MOISTURE AND MORE THAN PLENTIFUL OVER-WATER INSTABILITY (H8 TEMPERATURES DOWN AROUND -14/-15C PER RAP ANALYSIS) HELPING DRIVE THOSE LAKE SNOWS. FORECAST CONCERNS THROUGH THE SHORT TERM REAL CENTERED WITHIN THE FIRST HALF OF TODAY...CENTERING ON LINGERING LAKE INDUCED SNOW POTENTIAL AND POSSIBLE ADDITIONAL ACCUMULATIONS. RESPECTABLE LAKE SNOW PARAMETERS REMAIN IN PLACE EARLY ON THIS MORNING...WITH MORE THAN SUFFICIENT DELTA T/S AUGMENTED BY REMNANT DEEPER MOISTURE AND GOOD INVERSION LEVELS UP THROUGH H7 LEVELS. NNW (LAKE SUPERIOR) TO NW (NORTHERN LAKE MICHIGAN) FLOW REGIME WILL LOCKED IN BY SUNRISE...TARGETING THE NORTHWEST LOWER SNOWBELTS FOR THE MOST PERSISTENT AND HEAVIEST ACTIVITY. GIVEN FLOW...WOULD EXPECT BETTER LAKE SUPERIOR ACTIVITY TO REMAIN JUST WEST OF CHIPPEWA COUNTY. DECISIVE DOWNTURN IN LAKE SNOW PARAMETERS EXPECTED AFTER ABOUT 15Z...WITH STEADY LOSS OF SYNOPTIC MOISTURE SUPPORT AND LOWERING INVERSION LEVELS. DIURNAL DISRUPTION WILL ONLY HELP THE CAUSE..AS WILL DEEPENING OF SURFACE BASED DRY WEDGE. WOULD EXPECT SCATTERED LATE MORNING ACTIVITY TO COMPLETELY END BY EARLY AFTERNOON (YUP...SAID THAT BEFORE). UPSHOT TO ALL THE ABOVE...THINKING PERHAPS ANOTHER INCH OR SO IN NORTHWEST LOWER SNOWBELTS THIS MORNING...LEAVING THE INHERITED LAKE SNOW ADVISORY THROUGH ITS DURATION ENDING AT 15Z. LESS ACCUMULATION EXPECTED ELSEWHERE. DRYING REMAINS AGGRESSIVE THROUGH THE AFTERNOON...AND STILL EXPECT SKIES TO TREND PARTLY SUNNY TO SUNNY ALL AREAS. UNFORTUNATELY...EVEN MID APRIL SUN WILL DO LITTLE TO HELP THE TEMPERATURE CAUSE...WITH READINGS A SOLID 15 TO 20 DEGREES BELOW NORMAL. GUSTY NORTHWEST WINDS WILL SUBSIDE THROUGH THE DAY...BUT NOT BEFORE MAKING IT FEEL DOWNRIGHT COLD THROUGH THE EARLY AFTERNOON. MUCH QUIETER HEADING INTO TONIGHT AS DRYING BECOMES COMPLETE AND HIGH PRESSURE BUILDS DIRECTLY OVERHEAD. MOSTLY CLEAR SKIES...WITH PERHAPS A TOUCH OF HIGH CLOUDS LATE. RADIATION COOLING TRIFECTA... WITH QUICK LOSS OF WINDS...CLEAR SKIES..AND DRY LOW LEVELS. GUIDANCE CONTINUES TO TREND COLDER...NOW SHOWING THE TRADITIONAL ICE BOX LOCALES FLIRTING WITH THE UPPER SINGLE DIGITS. WILL NOT GO QUITE THIS AGGRESSIVE...USING LOWER TEENS FOR THE COLDER LOCATIONS. THESE NUMBERS FLIRT WITH RECORD LOWS FOR THE DAY...WITHIN A FEW DEGREES AT SEVERAL SITES. COULD EASILY SEE A RECORD TO TWO BROKEN BY SUNRISE SUNDAY. && .LONG TERM...(SUNDAY THROUGH FRIDAY) ISSUED AT 300 AM EDT SAT APR 20 2013 .SUNDAY AND MONDAY...STRONG SURFACE HIGH PRESSURE CENTER SHIFTS EAST OF MICHIGAN BY 12Z SUNDAY. AFTER A FRIGID START TO THE DAY...WITH EARLY MORNING LOWS IN THE TEENS (WHICH IS ROUGHLY 20 DEGREES BELOW NORMAL)...TEMPS WILL REBOUND NICELY AS SOUTHERLY FLOW KICKS IN ON THE BACK SIDE OF THE HIGH CENTER. CLOUDS WILL INCREASE/THICKEN/LOWER FROM WEST TO EAST AS MAINLY MID/UPPER LEVEL MOISTURE BEGINS TO ADVECT INTO THE WRN GREAT LAKES IN ADVANCE OF A COLD FRONT DRIVING EAST THRU MINNESOTA. STILL APPEARS ANY PRECIP CHANCES WILL HOLD OFF UNTIL SUNDAY NIGHT...AND WILL BE CONFINED TO MAINLY ERN UPR MICHIGAN. ONCE THE COLD FRONT REACHES WRN UPR MICHIGAN AND WISCONSIN...UPPER LEVEL FLOW BECOMES NEARLY PARALLEL WITH THE FRONT ITSELF...WHICH WILL SLOW ITS EASTWARD PROGRESS. ALSO...A WAVE DEVELOPS ALONG THE FRONT...DEEPENING INTO A CLOSED LOW THAT DRIVES NE THRU THE STRAITS ON TUESDAY (MORE ON THIS BELOW). WITH THE SLOW EASTWARD PUSH OF THE FRONT AND ASSOCIATED MOISTURE...POPS WILL GRADUALLY SPREAD FROM ERN UPR MICHIGAN SUNDAY NIGHT INTO THE STRAITS AND ALONG THE LAKE MICHIGAN SHORELINE TO LEELANAU COUNTY ON MONDAY...AND THEN FINALLY MAKE SOME HEADWAY INTO NRN LWR MICHIGAN WEST OF A LINE FROM ROGERS CITY TO HTL LATE MONDAY NIGHT AS THAT WAVE (MENTIONED ABOVE) BEGINS TO LIFT INTO OUR CWA. AGAIN...TEMPS WILL RECOVER NICELY DURING THE FIRST PART OF NEXT WEEK THANKS TO WAA AHEAD OF THE SLOW COLD FRONT. HIGHS ON SUNDAY WILL WARM INTO THE MID 40S TO LOWER 50S...BUT WILL COOL BACK INTO THE 30S AT NIGHT. HOWEVER...PRECIP SUNDAY NIGHT IN ERN UPR MICHIGAN SHOULD BE ALL LIQUID PER NAM BUFR SOUNDINGS SHOWING A SURFACE-BASED ABOVE FREEZING LAYER THRU 850 MB. WAA FURTHER STRENGTHENS ON MONDAY...WITH TEMPS CLIMBING TO NEAR 50 IN ERN UPR MICHIGAN AND WELL INTO THE 50S TO NEAR 60 ACROSS NRN LWR MICHIGAN. COLD FRONT REMAINS WEST OF OUR CWA MONDAY NIGHT. TEMPS WILL COOLING MAINLY BACK INTO THE 40S MONDAY NIGHT...KEEPING ANY PRECIP ALL LIQUID. TUESDAY THRU FRIDAY...AS MENTIONED ABOVE...FIRST WAVE TRACKS ALONG THE COLD FRONT AND THRU THE STRAITS TUESDAY MORNING. THIS FEATURE COMBINED WITH DEEP MOISTURE WILL PRODUCE RAIN SHOWERS ACROSS MUCH OF OUR CWA ON TUESDAY. SECOND WAVE DEVELOPS ALONG THE FRONT AND TRACKS THRU SRN LWR MICHIGAN TUESDAY NIGHT...SPREADING ANOTHER AREA OF RAIN SHOWERS THRU MOST OF MICHIGAN. WITH AREA RIVERS ALREADY RUNNING HIGH FROM RECENT RAIN AND SNOWMELT...WILL NEED TO KEEP AN EYE ON THE POTENTIAL FOR HEAVY RAINFALL ESPECIALLY WITH THIS SECOND WAVE AS IT BEGINS TO TAP INTO GULF MOISTURE TUESDAY NIGHT. FOR NOW...WILL STICK WITH LIKELY POPS FOR TUESDAY AND TUESDAY NIGHT ACROSS MOST OF OUR CWA. PRECIP CHANCES DIMINISH ON WEDNESDAY AS THE FRONT EXITS TO THE EAST COAST AND SURFACE RIDGING BUILDS INTO MICHIGAN. A WEAK MOISTURE-STARVED NRN STREAM WAVE QUICKLY SWINGS THRU MICHIGAN THURSDAY...PRODUCING A QUICK CHANCE OF LIGHT RAIN. DEEPER MOISTURE WILL BEGIN TO ADVECT INTO THE WRN GREAT LAKES ON FRIDAY ONCE SOUTHERLY RETURN FLOW KICKS IN ON THE BACK SIDE OF HIGH PRESSURE. FIRST LOOK AT NEXT WEEKEND LOOKS UNSETTLED WITH NEAR NORMAL TEMPS IN THE 50S. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT) ISSUED AT 1204 AM EDT SAT APR 20 2013 LOW PRESSURE NORTH OF GEORGIAN BAY WILL WEAKEN AND RAPIDLY MOVE EAST. BLUSTERY W TO NW WINDS WILL CONTINUE INTO SATURDAY...THEN GO LIGHT/VARIABLE. COLDER AIR WILL CONTINUE TO SPILL INTO THE REGION...AND LAKE EFFECT SNOW SHOWERS ARE ORGANIZING. HOWEVER...THE MAIN IMPACT WILL BE BETWEEN TVC AND PLN. DO EXPECT CIGS/VSBYS AT TVC/PLN TO LOWER TO MVFR LEVELS...AND VSBYS WILL REACH IFR CONDITIONS IN -SHSN AT TIMES...ESPECIALLY AT TVC. PRECIP AND CLOUDS DIMINISH DURING THE DAY ON SATURDAY. && .MARINE... ISSUED AT 300 AM EDT SAT APR 20 2013 SLOW...BUT STEADY...IMPROVEMENT EXPECTED ACROSS ALL WATERS TODAY AS HIGH PRESSURE BUILDS INTO THE REGION. REMNANT GUSTY NORTHWEST WINDS AND CHOPPY WAVES WILL REQUIRE SCA/S FOR NEARLY ALL WATERS...BUT ALL GALE WARNINGS WILL BE ALLOWED TO EXPIRE BY 12Z. RAPID IMPROVEMENT EXPECTED LATE THIS AFTERNOON AND EVENING AS WINDS GO LIGHT UNDER OVERHEAD HIGH PRESSURE. GUSTY SOUTHEAST WINDS DEVELOP SUNDAY...POSSIBLY REQUIRING ADDITIONAL SCA/S FOR SOME NEARSHORE WATERS. && .APX WATCHES/WARNINGS/ADVISORIES... MI...LAKE EFFECT SNOW ADVISORY UNTIL 11 AM EDT THIS MORNING FOR MIZ021-022-027-028. WINTER WEATHER ADVISORY UNTIL 5 AM EDT EARLY THIS MORNING FOR MIZ008. LH...GALE WARNING UNTIL 8 AM EDT THIS MORNING FOR LHZ345>349. LM...SMALL CRAFT ADVISORY UNTIL 5 PM EDT THIS AFTERNOON FOR LMZ323- 341-342-344>346. LS...GALE WARNING UNTIL 6 AM EDT EARLY THIS MORNING FOR LSZ321-322. && $$ SYNOPSIS...MR SHORT TERM...MB LONG TERM...MR AVIATION...JZ MARINE...MB
AREA FORECAST DISCUSSION...UPDATED
NWS TWIN CITIES/CHANHASSEN MN
654 AM CDT SAT APR 20 2013 .DISCUSSION... THERE ARE A FEW FORECAST ISSUES OF CONCERN OVER THE NEXT SEVERAL DAYS... AND THE S-WORD IS INVOLVED YET AGAIN. IN THE BIG PICTURE... WATER VAPOR IMAGERY AND RAP UPPER AIR ANALYSES CONTINUE TO SHOW AN ALL TOO FAMILIAR PATTERN OF RIDGING OFF THE WEST COAST WITH NORTHWEST UPPER FLOW INTO OUR AREA. THE UPPER TROUGH ASSOCIATED WITH OUR RECENT STORM HAS PUSHED EAST INTO THE GREAT LAKES... AND WE NOW AWAIT THE ARRIVAL OF SHORTWAVE ENERGY DROPPING SOUTHEAST INTO ALBERTA AND ANOTHER SHORTWAVE NEAR THE NEVADA/UTAH BORDER. THE SOUTHERN FEATURE WON/T DIRECTLY EFFECT US... ALTHOUGH IT WILL HELP IN PUSHING THE ELEVATED WARM FRONT THROUGH THE AREA LATE TONIGHT AND SUNDAY. THE NORTHERN WAVE WILL PASS BY TO OUR NORTH... BUT WILL STILL MANAGE TO DRAG A COLD FRONT BACK THROUGH THE AREA SUNDAY NIGHT. A SHORTWAVE FARTHER UPSTREAM OVER ALASKA WILL DROP INTO THE MEAN TROUGH SUNDAY INTO MONDAY AND MAKE THE TURN TO OUR SOUTH... LIFTING NORTHEAST THROUGH THE REGION LATE MONDAY INTO TUESDAY. THE GFS AND ECMWF HAVE COME INTO DECENT AGREEMENT IN THEIR HANDLING OF THIS FEATURE... ALTHOUGH THE ECMWF IS A BIT FARTHER WEST IN ITS PLACEMENT OF THE INVERTED TROUGH AND EVENTUAL SURFACE LOW TRACK... AND HAS THE RAIN/SNOW LINE A BIT FARTHER WEST AS A RESULT. FOR NOW... A COMPROMISE BETWEEN THE GFS AND ECMWF SEEMS TO BE THE MOST LOGICAL COURSE OF ACTION... ESPECIALLY GIVEN THE ECMWF SHIFTED TOWARD THE GFS SOLUTION WITH ITS MOST RECENT RUN. LOOK FOR THE SURFACE RIDGE TO DRIFT EAST ACROSS THE AREA TODAY... WITH SOME INCREASE IN MID-HIGH CLOUDS THROUGH THE DAY AS WE GET INTO RETURN FLOW AND SEE A BIT OF AN UPPER LEVEL RIDGE WORK ACROSS THE AREA. WARM ADVECTION PCPN SHOULD GET GOING TO OUR SOUTHWEST LATE THIS AFTERNOON AND SPREAD EAST ACROSS THE AREA TONIGHT. THE 290-295K ISENTROPIC LAYER OFF THE NAM AND GFS DOES A NICE JOB OF HIGHLIGHTING THE TIMING OF THINGS AND SUGGESTING WHERE THE BEST PCPN SHOULD OCCUR. FORECAST SOUNDINGS ARE GENERALLY SUPPORTIVE OF SNOW... AT LEAST INITIALLY... BEFORE WE SEE A BIT OF A WARM FRONT LIFT THROUGH SUNDAY MORNING AND CHANGE ANY LINGERING PCPN OVER TO RAIN. BEFORE THAT OCCURS THERE COULD BE SOME LIGHT ACCUMULATIONS... ALTHOUGH WOULDN/T EXPECT MUCH MORE THAN AN INCH WITH PCPN TOTALS GENERALLY MAXING OUT FROM ONE TO TWO TENTHS OF AN INCH. AS THE SHORTWAVE MOVES BY TO OUR NORTH TONIGHT WE WILL SEE A COLD FRONT MOVE THROUGH THE AREA. EXACTLY HOW FAR THAT BOUNDARY GETS DRAGGED SOUTHEAST WILL DICTATE WHERE THE BAROCLINIC ZONE... AND EVENTUALLY SURFACE LOW TRACK... WILL SETUP FOR THE MONDAY STORM SYSTEM. THE NAM APPEARS TOO FAR EAST... MUCH LIKE WITH THE LAST SYSTEM... WHILE THE ECMWF IS THE WESTERNMOST OF THE DETERMINISTIC SOLUTIONS. THE SREF MEAN IS EAST OF THE NAM AND WILL BE DISCOUNTED AT THIS POINT. ALL IN ALL... A BLEND OF THE GFS AND ECMWF LOOKS TO BE THE BEST GUESS AT THIS POINT... WHICH MEANS WE WILL ONCE AGAIN BE DEALING WITH A DECENT PCPN EVENT ACROSS THE AREA WITH MANY LOCATIONS LIKELY SEEING THINGS OCCUR IN THE FORM OF SNOW. FRONTOGENESIS IN THE 700-800MB LAYER REALLY GETS GOING MONDAY AFTERNOON... WITH WEAKLY STABLE AIR IN THE ZONE OF BEST FORCING... SO EXPECT TO SEE GOOD UPWARD MOTION IN ASSOCIATION WITH THE LOW- MID LEVEL DEFORMATION AND FRONTOGENESIS. THE GFS AND ECMWF BOTH MANAGE TO SQUEEZE OUT 0.5-0.75 INCHES OR SO OF PCPN... SO THERE IS DEFINITELY THE POTENTIAL FOR SEVERAL INCHES OF SNOW AND PERHAPS A BIT MORE DEPENDING ON WHERE THE RAIN/SNOW LINE SETS UP WITH RESPECT TO THE HEAVIEST PCPN. INCLUDED SOME 2 TO 5 INCH AMOUNTS IN THE FORECAST GRIDS... WITH A RAIN/SNOW LINE SIMILAR TO THE LAST EVENT... BUT CERTAINLY DON/T HAVE HIGH CONFIDENCE AT THIS POINT. SOME LIGHT PCPN COULD LINGER INTO TUESDAY ACROSS THE EAST... BUT ANY ADDITIONAL PCPN AMOUNTS SHOULD BE LIGHT. HIGH PRESSURE WILL THEN BUILD INTO THE AREA THROUGH WEDNESDAY... WITH SOME PERIODIC PCPN CHANCES RETURNING TO THE REGION FOR THE LATTER HALF OF THE WEEK AS A FEW QUICKLY MOVING SHORTWAVES EMBEDDED IN THE WEST/NORTHWEST FLOW ROTATE THROUGH THE AREA. PCPN-TYPE WITH EACH SYSTEM WILL DEPEND TO SOME EXTENT ON THE TIME OF DAY... SINCE TEMPERATURES ALOFT WILL BE SUFFICIENTLY COLD FOR SNOW UNTIL FRIDAY... BUT BOUNDARY LAYER TEMPERATURES DURING THE DAYTIME SHOULD KEEP THINGS RAIN. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SUNDAY MORNING) ISSUED AT 643 AM CDT SAT APR 20 2013 A RIDGE AXIS WILL SLIDE OVER THE CWA TODAY PROVIDING CLEAR SKIES AND LIGHT WINDS. AS THE RIDGE PUSHES EAST...LGT/VAR WINDS WILL BECOME SOUTHEAST AND STRENGTHEN THIS EVENING. A WARM FRONT WILL BRING A BAND OF SNOW ACROSS THE REGION TONIGHT WITH MVFR VIS EXPECTED. CIGS ARE MORE QUESTIONABLE DUE TO LOW LEVEL DRY AIR...HOVERING AROUND THE 3KFT LEVEL. KMSP...VFR UNTIL LATE TONIGHT WITH THE ARRIVAL OF THE SNOW. THEREAFTER...MVFR CONDITIONS EXPECTED. /OUTLOOK FOR KMSP/ SUN AFTN...MVFR WITH -RA. IFR CIGS PSBL. SSE WIND 10-15 KTS. SUN NGT...MVFR WITH -RA/-SN PSBL. WIND BCMG NW 5 TO 10 KTS. MON...MVFR WITH -SN. IFR CIGS PSBL. NW WIND 15-20 KTS. TUE...VFR. NW WIND 10-15 KTS. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...NONE. WI...NONE. && $$ DISCUSSION...TRH AVIATION...BORGHOFF
AREA FORECAST DISCUSSION
NWS TWIN CITIES/CHANHASSEN MN
335 AM CDT SAT APR 20 2013 .DISCUSSION... THERE ARE A FEW FORECAST ISSUES OF CONCERN OVER THE NEXT SEVERAL DAYS... AND THE S-WORD IS INVOLVED YET AGAIN. IN THE BIG PICTURE... WATER VAPOR IMAGERY AND RAP UPPER AIR ANALYSES CONTINUE TO SHOW AN ALL TOO FAMILIAR PATTERN OF RIDGING OFF THE WEST COAST WITH NORTHWEST UPPER FLOW INTO OUR AREA. THE UPPER TROUGH ASSOCIATED WITH OUR RECENT STORM HAS PUSHED EAST INTO THE GREAT LAKES... AND WE NOW AWAIT THE ARRIVAL OF SHORTWAVE ENERGY DROPPING SOUTHEAST INTO ALBERTA AND ANOTHER SHORTWAVE NEAR THE NEVADA/UTAH BORDER. THE SOUTHERN FEATURE WON/T DIRECTLY EFFECT US... ALTHOUGH IT WILL HELP IN PUSHING THE ELEVATED WARM FRONT THROUGH THE AREA LATE TONIGHT AND SUNDAY. THE NORTHERN WAVE WILL PASS BY TO OUR NORTH... BUT WILL STILL MANAGE TO DRAG A COLD FRONT BACK THROUGH THE AREA SUNDAY NIGHT. A SHORTWAVE FARTHER UPSTREAM OVER ALASKA WILL DROP INTO THE MEAN TROUGH SUNDAY INTO MONDAY AND MAKE THE TURN TO OUR SOUTH... LIFTING NORTHEAST THROUGH THE REGION LATE MONDAY INTO TUESDAY. THE GFS AND ECMWF HAVE COME INTO DECENT AGREEMENT IN THEIR HANDLING OF THIS FEATURE... ALTHOUGH THE ECMWF IS A BIT FARTHER WEST IN ITS PLACEMENT OF THE INVERTED TROUGH AND EVENTUAL SURFACE LOW TRACK... AND HAS THE RAIN/SNOW LINE A BIT FARTHER WEST AS A RESULT. FOR NOW... A COMPROMISE BETWEEN THE GFS AND ECMWF SEEMS TO BE THE MOST LOGICAL COURSE OF ACTION... ESPECIALLY GIVEN THE ECMWF SHIFTED TOWARD THE GFS SOLUTION WITH ITS MOST RECENT RUN. LOOK FOR THE SURFACE RIDGE TO DRIFT EAST ACROSS THE AREA TODAY... WITH SOME INCREASE IN MID-HIGH CLOUDS THROUGH THE DAY AS WE GET INTO RETURN FLOW AND SEE A BIT OF AN UPPER LEVEL RIDGE WORK ACROSS THE AREA. WARM ADVECTION PCPN SHOULD GET GOING TO OUR SOUTHWEST LATE THIS AFTERNOON AND SPREAD EAST ACROSS THE AREA TONIGHT. THE 290-295K ISENTROPIC LAYER OFF THE NAM AND GFS DOES A NICE JOB OF HIGHLIGHTING THE TIMING OF THINGS AND SUGGESTING WHERE THE BEST PCPN SHOULD OCCUR. FORECAST SOUNDINGS ARE GENERALLY SUPPORTIVE OF SNOW... AT LEAST INITIALLY... BEFORE WE SEE A BIT OF A WARM FRONT LIFT THROUGH SUNDAY MORNING AND CHANGE ANY LINGERING PCPN OVER TO RAIN. BEFORE THAT OCCURS THERE COULD BE SOME LIGHT ACCUMULATIONS... ALTHOUGH WOULDN/T EXPECT MUCH MORE THAN AN INCH WITH PCPN TOTALS GENERALLY MAXING OUT FROM ONE TO TWO TENTHS OF AN INCH. AS THE SHORTWAVE MOVES BY TO OUR NORTH TONIGHT WE WILL SEE A COLD FRONT MOVE THROUGH THE AREA. EXACTLY HOW FAR THAT BOUNDARY GETS DRAGGED SOUTHEAST WILL DICTATE WHERE THE BAROCLINIC ZONE... AND EVENTUALLY SURFACE LOW TRACK... WILL SETUP FOR THE MONDAY STORM SYSTEM. THE NAM APPEARS TOO FAR EAST... MUCH LIKE WITH THE LAST SYSTEM... WHILE THE ECMWF IS THE WESTERNMOST OF THE DETERMINISTIC SOLUTIONS. THE SREF MEAN IS EAST OF THE NAM AND WILL BE DISCOUNTED AT THIS POINT. ALL IN ALL... A BLEND OF THE GFS AND ECMWF LOOKS TO BE THE BEST GUESS AT THIS POINT... WHICH MEANS WE WILL ONCE AGAIN BE DEALING WITH A DECENT PCPN EVENT ACROSS THE AREA WITH MANY LOCATIONS LIKELY SEEING THINGS OCCUR IN THE FORM OF SNOW. FRONTOGENESIS IN THE 700-800MB LAYER REALLY GETS GOING MONDAY AFTERNOON... WITH WEAKLY STABLE AIR IN THE ZONE OF BEST FORCING... SO EXPECT TO SEE GOOD UPWARD MOTION IN ASSOCIATION WITH THE LOW- MID LEVEL DEFORMATION AND FRONTOGENESIS. THE GFS AND ECMWF BOTH MANAGE TO SQUEEZE OUT 0.5-0.75 INCHES OR SO OF PCPN... SO THERE IS DEFINITELY THE POTENTIAL FOR SEVERAL INCHES OF SNOW AND PERHAPS A BIT MORE DEPENDING ON WHERE THE RAIN/SNOW LINE SETS UP WITH RESPECT TO THE HEAVIEST PCPN. INCLUDED SOME 2 TO 5 INCH AMOUNTS IN THE FORECAST GRIDS... WITH A RAIN/SNOW LINE SIMILAR TO THE LAST EVENT... BUT CERTAINLY DON/T HAVE HIGH CONFIDENCE AT THIS POINT. SOME LIGHT PCPN COULD LINGER INTO TUESDAY ACROSS THE EAST... BUT ANY ADDITIONAL PCPN AMOUNTS SHOULD BE LIGHT. HIGH PRESSURE WILL THEN BUILD INTO THE AREA THROUGH WEDNESDAY... WITH SOME PERIODIC PCPN CHANCES RETURNING TO THE REGION FOR THE LATTER HALF OF THE WEEK AS A FEW QUICKLY MOVING SHORTWAVES EMBEDDED IN THE WEST/NORTHWEST FLOW ROTATE THROUGH THE AREA. PCPN-TYPE WITH EACH SYSTEM WILL DEPEND TO SOME EXTENT ON THE TIME OF DAY... SINCE TEMPERATURES ALOFT WILL BE SUFFICIENTLY COLD FOR SNOW UNTIL FRIDAY... BUT BOUNDARY LAYER TEMPERATURES DURING THE DAYTIME SHOULD KEEP THINGS RAIN. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT) ISSUED AT 1145 PM CDT FRI APR 19 2013 A RIDGE OF HIGH PRESSURE OVER THE NORTHERN PLAINS WILL MOVE ACROSS THE TAF SITES ON SATURDAY. LIGHT NW WINDS OVERNIGHT WILL BECOME SE ON THE BACKSIDE OF THE HIGH SATURDAY AFTERNOON. THE MAIN CONCERNS DURING THE TAF PERIOD ARE MVFR CEILINGS AND LIGHT SNOW SPREADING ACROSS THE TAF SITES SATURDAY NIGHT AND EARLY SUNDAY FROM WEST TO EAST. CONFIDENCE IS HIGH ON BOTH OCCURRING. FOR NOW...STARTED MVFR/-SN IN THE KRWF AND KAXN TAFS IN THE 03Z/04Z TIME FRAME RESPECTIVELY WITH THE ACTIVITY REACHING KMSP AROUND 21/08Z. KMSP...NO PROBLEMS OVERNIGHT AND SATURDAY AS HIGH PRESSURE BUILDS IN. NW WINDS THROUGH DAYBREAK UP TO 10 KNOTS THEN BECOMING MORE 330-350 AT 4-6 KNOTS DURING THE MORNING. THE WINDS WILL TRANSITION TO SE (110-130) DURING THE AFTERNOON WITH SPEEDS INCREASING TO 7-9 KNOTS BY EVENING. MVFR WITH -SN EXPECTED EARLY SUNDAY MORNING. /OUTLOOK FOR KMSP/ SUN AFTN...MVFR WITH -RA. IFR CIGS PSBL. SSE WIND 10-15 KTS. SUN NGT...MVFR WITH -RA/-SN PSBL. WIND BCMG NW 5 TO 10 KTS. MON...MVFR WITH -SN. IFR CIGS PSBL. NW WIND 15-20 KTS. TUE...VFR. NW WIND 10-15 KTS. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...NONE. WI...NONE. && $$
AREA FORECAST DISCUSSION
NWS RALEIGH NC
640 AM EDT SAT APR 20 2013 .SYNOPSIS... A STRONG COLD FRONT SWEEPS OFFSHORE THIS MORNING. IN THE WAKE OF THE COLD FRONT...COOLER HIGH PRESSURE BUILDS INTO THE REGION FROM THE NORTH OVER THE WEEKEND. A WEAK LOW PRESSURE SYSTEM DEVELOPS OFF THE CAROLINA COAST LATE SUNDAY NIGHT INTO MONDAY. && .NEAR TERM /THROUGH TODAY/... AS OF 640 AM SATURDAY... DRY AIR IN THE MID-LEVELS CONTINUED TO SLOWLY MOVE OVER THE WESTERN PART OF THE STATE ON WATER VAPOR IMAGERY...THOUGH APPARENT MID-LEVEL SHORTWAVES IN THE SOUTHWEST FLOW ALOFT WERE RESULTING IN A RIPPLED APPEARANCE TO THE MOISTURE ON WATER VAPOR LOOPS. THE LATEST WSR-88D COMPOSITE WAS FAIRLY SIMILAR TO AN EVENING RUN OF THE HIGH-RES RAPID REFRESH WRF...AND NUMEROUS SHOWERS HAD JUST MOVED EAST OF THE INTERSTATE 95 CORRIDOR. IN THE SOUTHWEST FLOW ALOFT... HIGH-LEVEL RELATIVE HUMIDITY FORECASTS FROM THE NAM...RUC...AND THE GFS SUGGEST A SLOW CLEARING TREND TO THE HIGH CLOUDS DURING THE DAY...WITH THE GFS AND RUC SLOWEST AND SUGGESTIVE OF THE WESTERN EDGE OF THE CIRRUS SHIELD NOT GETTING MUCH PAST INTERSTATE 95 UNTIL AS LATE AS 20Z. THE FORECAST FOR TODAY WILL FEATURE A GRADUAL WEST-TO-EAST CLEARING TREND WITH HIGHS IN THE MID 60S...NEAR THE WARMER GUIDANCE OF THE MAV TOWARD THE TRIAD AND NEAR COOLER VALUES OR EVEN A DEGREE OR TWO BELOW GUIDANCE FARTHER EAST. WINDS WILL BECOME NORTHWEST IN THE FRONTAL TROUGH EARLY THIS MORNING ACROSS CENTRAL NORTH CAROLINA...WITH A SLACKENING GRADIENT FORECAST BY BOTH THE NAM AND THE GFS BY AFTERNOON AS WINDS VEER TO NORTH TO NORTHEAST AND BECOME LIGHT BY EVENING. && .SHORT TERM /TONIGHT THROUGH MONDAY NIGHT/... AS OF 305 AM SATURDAY... TONIGHT AND SUNDAY... HIGH PRESSURE BUILDS INTO CENTRAL NORTH CAROLINA OVERNIGHT...AND THE GRADIENT TIGHTENS WITH THE RIDGING. IN ADDITION...IN THE WEST-SOUTHWEST FLOW ALOFT...BOTH THE NAM AND THE GFS SUGGEST AN INCREASE IN UPPER-LEVEL MOISTURE MOVING INTO THE REGION OVERNIGHT. THE MIXING THAT SHOULD OCCUR OVERNIGHT AS THE HIGH BUILDS IN...WITH AN INCREASE IN THE WIND...ALONG WITH SOME HIGH CLOUDS...SHOULD KEEP TEMPERATURES FROM FALLING TOO FAR. GUIDANCE MINS APPEAR REASONABLE... WITH MOST LOCATIONS SEEING LOWS IN THE UPPER 30S TO AROUND 40 DEGREES...POSSIBLY A CATEGORY COOLER IN THE TYPICALLY COOLER AREAS NORTHEAST OF THE TRIANGLE...WHERE ANY HIGH CLOUDS WILL ARRIVE LATER. SUNDAY...HIGH PRESSURE REMAINS OVER THE AREA AND SUBSIDENCE CONTINUES. UNDER AREAS OF HIGH CLOUDS BASED ON THE UPPER-LEVEL RELATIVE HUMIDITY FIELDS OF THE NAM AND GFS...AND WITH A MODEERATELY GUSTY NORTHEAST WIND WITH 1000-850MB THICKNESSES ABOUT 10METERS LESS ON AVERAGE COMPARED TO TODAY...HIGHS SHOULD BE SLIGHTLY COOLER... MAINLY 60 TO 65. SUNDAY NIGHT...DIFFERENCES IN THE NAM AND GFS START TO SHOW THEMSELVES MORE PROMINENTLY. THE GFS IS FLATTER WITH THE UPPER FLOW AND THE 500MB JET IS ORIENTED MORE WEST-TO-EAST AND FARTHER SOUTH OVER SOUTHERN SOUTH CAROLINA BY 12Z MONDAY. THIS KEEPS THE BEST LIFT AND MOISTURE ALONG AND NEAR THE COAST...POSSIBLY PENETRATING INLAND TOWARD KCTZ. ON THE OTHER HAND...THE NAM IS JUST SLIGHTLY SHARPER WITH THE UPPER TROUGH AND ITS MID-LEVEL JET BECOMES ORIENTED A LITTLE MORE SOUTHWEST-TO-NORTHEAST. THIS RESULTS IN CLOUDS PENETRATING FARTHER INLAND ALONG WITH CHANCES FOR PRECIPITATION. THE NAM PRECIPITABLE WATER OVER THE SOUTHWEST PIEDMONT...WHERE IT FORECASTS MEAGER QPF LATE SUNDAY NIGHT...IS ONLY ABOUT AS HIGH AS A HALF-INCH UNDER MID-LEVEL NVA...AND BUFR SOUNDINGS FROM THE NAM CLEARLY SHOW AMPLE MID-LEVEL DRYING PERSISTING UNTIL 12Z MONDAY OVER MUCH OF CENTRAL NORTH CAROLINA. THINK THE BETTER CHANCES OF ANY MEASURABLE RAIN WILL BE AS PREVIOUSLY FORECAST AND MAINLY ORIENTED LATE SUNDAY NIGHT ALONG AND EAST OF A LINE FROM ABOUT KMEB TO KGSB... A LITTLE MORE SIMILAR TO THE GFS. HOWEVER...THERE IS CONCERN ABOUT THE DEGREE IN WHICH SOME LOW-LEVEL MOISTURE WILL BE ABLE TO PENETRATE INLAND IN A PERSISTENT NORTHEAST FLOW THAT BECOMES MORE EASTERLY OVERNIGHT. LEANED A LITTLE MORE TOWARD THE NAM IN THAT RESPECT. REGARDLESS...CONFIDENCE DOES START TO DECREASE WITH THE FORECAST OVERNIGHT SUNDAY...BUT FOR THIS FORECAST WILL FEATURE AN INCREASE IN CLOUDS WITH ONLY A CHANCE OF RAIN MAINLY SOUTHEAST WITH OVERNIGHT LOWS A BLEND OF THE MAV AND MET MOS GUIDANCE...MAINLY 40 TO 45. -DJF MONDAY AND MONDAY NIGHT... DIFFICULT FORECAST FOR THIS PERIOD...AS A WEAK SHORTWAVE IS EXPECTED TO MOVE ACROSS THE AREA IN THE BROAD CYCLONIC FLOW ACROSS THE CONUS AND INDUCE CYCLOGENESIS JUST OFF THE SOUTHEAST U.S. COAST ALONG THE LINGERING OLD FRONTAL ZONE. THIS SURFACE LOW IS EXPECTED TO TRACK NORTH-NORTHEASTWARD JUST OFF THE COAST OF THE CAROLINAS MONDAY AND MONDAY NIGHT. HOW CLOSE TO THE COAST THIS SURFACE LOW TRACKS AS IT PASSES BY THE COAST OF THE CAROLINAS WILL HAVE A SIGNIFICANT IMPACT ON HOW MUCH RAIN AND CLOUD COVER WE WILL SEE... ALONG WITH A BIG IMPACT ON HIGH AND LOW TEMPS. THUS...FORECAST CONFIDENCE WITH REGARD TO THESE ITEMS IS LOW AT THIS TIME. THE 00Z NAM AND 12Z ECMWF SHOW THE SURFACE LOW TRACKING CLOSER TO OUR COAST THAN THE 00Z GFS...WITH THE 12Z ECENS MEAN GIVEN SUPPORT TO A NAM/ECMWF BLEND. THUS...WILL GO WITH A BLEND OF THE NAM/ECMWF...WHICH FAVORS A CHANCE FOR LIGHT RAIN ACROSS AT LEAST EASTERN PORTIONS OF CENTRAL NC...AND MOSTLY CLOUDY TO OVERCAST SKIES. WILL CONTINUE TO TREND HIGH TEMPS COOLER THAN GUIDANCE... GIVEN THE STRONG 1043-1045 MB SURFACE HIGH EXTENDING SOUTHWARD INTO OUR AREA DURING THIS TIME FROM NEW ENGLAND/SOUTHEAST CANADA. THIS WOULD FAVOR THE DEVELOPMENT OF A CAD AIRMASS ACROSS CENTRAL NC... SO WILL GO WITH HIGH TEMPS IN THE UPPER 50S ACROSS THE AREA...WITH THE POTENTIAL FOR HIGHS POSSIBLY A CATEGORY COOLER IF MORE PRECIP IS REALIZED THAN CURRENTLY EXPECTED (TRACE WEST TO NEAR A TENTH OF AN INCH EAST). WITH RESPECT TO POPS WILL KEEP CHANCE EAST TO SLIGHT CHANCE WEST FOR NOW MONDAY INTO MONDAY EVENING...WITH ONLY LIGHT RAINFALL AMOUNTS EXPECTED THOUGH. THE SURFACE LOW SHOULD BE LIFTING OFF TO THE NORTHEAST EARLY TUESDAY MORNING...ALONG WITH THE PASSAGE OF THE MID LEVEL SHORTWAVE. THIS SHOULD USHER DRIER AIR ALOFT INTO THE AREA...ALONG WITH A MORE NORTHERLY COMPONENT TO THE LOW LEVEL FLOW (VS THE MOIST EASTERLY FLOW). WILL SHOW CHANCES FOR PRECIP ENDING EARLY TUESDAY MORNING...HOWEVER...STILL THINK WE WILL HOLD ONTO OUR LOW CLOUD UNTIL AT LEAST SUNRISE. THUS...EXPECT LOWS TO BE ON THE WARMER SIDE OF GUIDANCE...GIVEN THE EXPECTED CLOUD COVER (AS THE GFS HAS MUCH LESS CLOUD COVER)...AND WILL GO WITH LOW TEMPS RANGING FROM THE MID 40S WEST TO AROUND 50 EAST. -BSD && .LONG TERM /TUESDAY THROUGH FRIDAY/... AS OF 305 AM SATURDAY... BRIEF SHORTWAVE RIDGING IS EXPECTED TO BUILD ACROSS THE REGION ON TUESDAY... BEFORE THE NEXT SIGNIFICANT TROUGH AND ASSOCIATED COLD FRONT APPROACH THE AREA ON WEDNESDAY AND CROSS THE REGION LATE WEDNESDAY INTO WEDNESDAY NIGHT.... WITH SHOWERS AND/OR STORMS POSSIBLY LINGERING INTO THURSDAY MORNING. HOWEVER... GIVEN THE SURFACE RIDGE IS EXPECTED TO HOLD ACROSS THE AREA UNTIL TUESDAY NIGHT... THERE WILL ONLY BE A BRIEF PERIOD OF A MOISTENING SOUTHERLY RETURN FLOW. THUS... GIVEN THIS AND THE POSSIBILITY OF THE TROUGH ALOFT BEGIN A BIT WEAKER... THINK THIS SYSTEM (AS IT STANDS NOW) SHOULD BE MUCH WEAKER THAN THE ONE WHICH JUST MOVED THROUGH THE AREA YESTERDAY/EARLY THIS MORNING. THINK WE SHOULD SEE A BAND OF SHOWERS AND PERHAPS A FEW THUNDERSTORMS LATE WEDNESDAY INTO WEDNESDAY NIGHT/THURSDAY MORNING AS THE LOW LEVEL FRONTAL ZONE MOVES ACROSS THE AREA. HIGH PRESSURE WILL BUILD INTO CENTRAL NC IN THE WAKE OF THE SYSTEM ON THURSDAY AFTERNOON... AND REMAIN ACROSS THE AREA THROUGH THE END OF THE FORECAST PERIOD (FRIDAY). HIGH TEMPS DURING THE EXTEND WILL GENERALLY RUN BELOW NORMAL... WITH THE WARMEST DAY EXPECTED TO BE WEDNESDAY. WILL FORECAST HIGHS IN THE 70S AREAWIDE WEDNESDAY... WITH GENERALLY MID TO UPPER 60S (NEAR 70 SOUTH) FOR TUESDAY AND THURSDAY/FRIDAY. LOW TEMPS ARE EXPECTED TO BE IN THE LOWER 50S ON WEDNESDAY MORNING IN ADVANCE OF THE FRONT... WITH GENERALLY 40S THURSDAY AND FRIDAY MORNINGS. && .AVIATION /12Z SATURDAY THROUGH WEDNESDAY/... AS OF 640 AM SATURDAY... VFR CONDITIONS ARE EXPECTED THROUGH THE 12Z VALID TAF PERIOD... OUTSIDE OF A FEW AREAS OF MVFR CONDITIONS IN RAIN SHOWERS VERY EARLY THIS MORNING SOUTH AND EAST OF KRWI AS A COLD FRONT MOVES OFFSHORE. IN THE SOUTHWEST FLOW ALOFT...THE BACK EDGE OF HIGH CLOUDS SHOULD BE SLOW TO MOVE EAST. EVENTUALLY...BY 20Z...THAT BACK EDGE SHOULD BE THROUGH THE CENTRAL NORTH CAROLINA COASTAL PLAIN. BEYOND THE 12Z VALID TAF PERIOD...VFR CONDITIONS OCCUR SUNDAY INTO SUNDAY NIGHT. THERE IS A CHANCE OF MVFR CONDITIONS IN LOWER CLOUDS SPREADING FROM THE COAST TOWARD CENTRAL NORTH CAROLINA BY LATE SUNDAY NIGHT. THIS WILL DEPEND ON HOW CLOSE TO THE COAST WEAK LOW PRESSURE DEVELOPS WITH THE GUIDANCE DIFFERING ON THE AMOUNT AND TYPE OF CLOUD COVER THAT OCCURS OVER CENTRAL NORTH CAROLINA THEN. HIGHER CHANCES OF THESE CLOUDS WILL BE TOWARD KFAY AND KRWI. THERE IS THEN A CHANCE OF IFR CONDITIONS IN LOW CLOUDS MONDAY NIGHT INTO EARLY TUESDAY...AND AGAIN EARLY WEDNESDAY...WITH AREAS OF MVFR CLOUDS POSSIBLE BEFORE MIXING LIFTS ANY MVFR CLOUD HEIGHTS TO VFR DURING WEDNESDAY AFTERNOON. && .RAH WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SYNOPSIS...DJF NEAR TERM...DJF SHORT TERM...DJF/BSD LONG TERM...BSD AVIATION...DJF
AREA FORECAST DISCUSSION
NWS PUEBLO CO
312 PM MDT SAT APR 20 2013 .SHORT TERM...(THIS EVENING THROUGH SUNDAY) ISSUED AT 312 PM MDT SAT APR 20 2013 SHORTWAVE PUSHING EASTWARD ACROSS COLORADO THIS AFTERNOON WAS PRODUCING A GOOD DEAL OF VIRGA/LIGHT SHOWERS OVER THE MOUNTAINS...THOUGH AMOUNT OF PRECIP REACHING THE GROUND IS LIKELY MUCH LESS THAN RADAR SUGGESTS. HAVE EVEN SEE A COUPLE LIGHTNING STRIKES OVER THE SRN SAN LUIS VALLEY NEAR THE NM BORDER...AS LAPS/HRRR SUGGEST A LOCAL MAX OF INSTABILITY OVER THE VALLEY. NOT SEEING MUCH SNOW YET ON CENTRAL MOUNTAIN WEB CAMS...THOUGH WILL KEEP SNOW ADVISORY IN PLACE THE NEXT FEW HOURS TO ACCOUNT FOR SOME BRIEF BURSTS OF SNOW UNDER HEAVIER CONVECTIVE SHOWERS. ELSEWHERE...WILL KEEP SCATTERED POPS OVER THE MOUNTAINS INTO THE EVENING...WITH SOME ISOLATED POPS FOR MAINLY VIRGA/SPRINKLES ALONG THE I-25 CORRIDOR. COULD ALSO SEE SOME BRIEF GUSTY/ERRATIC WINDS OVER LOWER ELEVATIONS AS PRECIP EVAPORATES WITHIN THE DRY SUB-CLOUD LAYER. DIDN`T INCLUDE A MENTION OF THUNDER IN ANY AREAS...AS LATEST HRRR KEEP BEST INSTABILITY NORTH OF THE PALMER DIVIDE. EXPECT MOST PRECIP TO END QUICKLY WITH SUNSET AS INSTABILITY WANES AND UPPER WAVE MOVES RAPIDLY INTO THE CENTRAL PLAINS. ON SUNDAY...WEAK SHORTWAVE MAY SPARK SOME VIRGA/SPRINKLES OVER THE MTNS...BUT COVERAGE WILL BE MUCH LESS THAN TODAY. MODELS TRY TO BREAK OUT SOME SPRINKLES OVER THE FAR EASTERN PLAINS AS WELL...AS MODEST LOW LEVEL MOISTURE RETURNS NORTHWARD. WILL IGNORE THIS FOR NOW...AS ANY PRECIP WILL BE VERY LIGHT. WEST WINDS WILL PICK UP MOST AREAS AS UPPER JET MOVES ACROSS AND FLOW IN THE 500/700 MB LAYER INCREASES TO 30-40 KNOTS...AND LOCATIONS ACROSS THE HIGHER ELEVATIONS OF THE SANGRES/SAWATCH RANGES WILL BECOME FAIRLY GUSTY BY AFTERNOON. MAX TEMPS LOOK WARMER MOST AREA WITH BETTER MIXING AND A SUBTLE RISE IN 700 MB TEMPS...THOUGH AT BEST...READINGS WILL STILL COME UP A COUPLE DEGF SHORT OF SEASONAL MAXES. .LONG TERM...(SUNDAY NIGHT THROUGH SATURDAY) ISSUED AT 312 PM MDT SAT APR 20 2013 ...ANOTHER STRONG COLD FRONT TO AFFECT THE AREA MONDAY AFTERNOON THROUGH TUESDAY... SUNDAY NIGHT-TUESDAY...LATEST MODELS IN DECENT AGREEMENT ON DEVELOPING SYNOPTIC PATTERN THROUGH THE PERIOD...THOUGH CONTINUE TO DIFFER ON AMOUNTS OF GENERATED PRECIPITATION. AT ANY RATE...WILL SEE INCREASING WESTERLY FLOW ALOFT ACROSS THE REGION SUNDAY NIGHT AS AN EMBEDDED SHORT WAVE EJECTS ACROSS THE NORTHERN ROCKIES AHEAD OF PARENT TROUGH DIGGING INTO THE NORTHERN GREAT BASIN. COULD SEE A FEW SHOWERS ACROSS MAINLY THE CENTRAL MTS THROUGH THE PIKES PEAK REGION EARLY SUNDAY EVENING WITH FIRST PASSING WAVE WITH AN ASSOCIATED LEE TROUGH TRANSLATING ACROSS THE EASTERN PLAINS KEEPING OVERNIGHT LOWS ON THE MILD SIDE. MODERATE TO STRONG WEST TO SOUTHWEST FLOW ALOFT PERSISTS ACROSS THE AREA MONDAY AS PARENT SYSTEM CONTINUES TO TRANSLATE ACROSS THE ROCKIES WITH FLOW ALOFT BECOMING MORE WEST TO NORTHWEST MONDAY NIGHT AND TUESDAY AS UPPER TROUGH CONTINUES TO LIFT OUT ACROSS THE CENTRAL HIGH PLAINS. MID LEVEL MOISTURE SLOWLY INCREASES FROM WEST TO EAST ACROSS THE AREA MONDAY MORNING WITH A STRONG BACKDOOR COLD PUSHING ACROSS EASTERN COLORADO LATE MONDAY MORNING AND AFTERNOON. MODELS A TAD SLOWER WITH FRONT AND HAVE WARMED UP HIGHS SOME ACROSS EASTERN COLORADO...WITH THE WARMEST READINGS EXPECTED SOUTH AND WEST OF THE HIGHWAY 50 CORRIDOR. WITH THE INCREASING OROGRAPHIC FLOW AND UVV AHEAD OF WAVE...SHOULD SEE SNOW INCREASING IN COVERAGE AND INTENSITY ACROSS THE CENTRAL MTS MONDAY MORNING AND SPREADING EAST ACROSS THE UPPER ARKANSAS RIVER VALLEY INTO THE PIKES PEAK REGION THROUGH THE EARLY AFTERNOON. MODEL SOUNDINGS INDICATING LOWER ELEVATIONS RAPIDLY SATURATING BEHIND FRONT WITH RAIN DEVELOPING ALONG AND BEHIND THE FRONT. RAIN BECOMES MIXED WITH AND CHANGES TO SNOW LATE IN THE AFTERNOON AND EARLY EVENING...ESPECIALLY ACROSS THE PALMER DVD...WITH A POSSIBLE MESSY MONDAY EVENING COMMUTE. MODELS DIFFER ON AMOUNT OF QPF ACROSS THE SE MTS MONDAY NIGHT THOUGH AGREE ON A BAND OF MODERATE PRECIP DEVELOPING ACROSS THE CENTRAL MTS THROUGH THE PIKES REGION MONDAY NIGHT THROUGH EARLY TUESDAY MORNING AS RRQUAD OF JET TRANSLATES ACROSS SOUTH CENTRAL COLORADO. MAY NEED SOME HIGHLIGHTS ACROSS THE CENTRAL MTS AND POSSIBLE THE PIKES PEAK REGION IF LATEST MODELS REMAIN TRUE. COOL UPSLOPE FLOW PERSISTS ACROSS THE PLAINS ON TUESDAY...WITH HIGHS WELL BELOW SEASONAL AVERAGES...ESPECIALLY ACROSS THE EASTERN PLAINS. WEDNESDAY-SATURDAY...A WARMING TREND TO NEAR SEASONAL AVERAGES EXPECTED THROUGH THE PERIOD AS MODERATE NORTHWEST FLOW ALOFT PERSISTS ACROSS THE REGION. A FEW EMBEDDED SHORT WAVE PROGGED TO TRANSLATE THROUGH THE FLOW THURSDAY AND FRIDAY...OWNING TO A FEW AFTERNOON AND EVENING SHOWERS ACROSS MAINLY THE HIGHER TERRAIN. && .AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SUNDAY EVENING) ISSUED AT 312 PM MDT SAT APR 20 2013 UPPER WAVE OVER COLORADO WILL PRODUCE SHOWERS OVER THE HIGHER TERRAIN UNTIL 03Z...AND PERIODS OF MVFR/IFR CONDITIONS MAY OCCUR UNDER SOME OF THE HEAVIER PRECIPITATION. AT THE TAF SITES...KEPT A MENTION OF VCSH AT KCOS AND KALS UNTIL 02Z-03Z...THOUGH WITH DRY LOW LEVELS...SUSPECT WE`LL SEE MORE VIRGA AND GUSTY WINDS THAN ANY LOWER CIGS/VIS. MAY ALSO SEE SOME -SHRA/VIRGA W/NW OF KPUB UNTIL 02Z...AND GUSTY/ERRATIC WINDS WILL BE POSSIBLE AT THE TERMINAL THROUGH SUNSET. VFR CONDITIONS RETURN TO ALL AREAS BY 06-09Z AS ANY SHOWERS DISSIPATE. ON SUNDAY...VFR CONDITIONS EXPECTED MOST AREAS WITH ONLY MINOR/ISOLATED LATE AFTERNOON -SHRA OVER THE MTS. && .PUB WATCHES/WARNINGS/ADVISORIES... WINTER WEATHER ADVISORY UNTIL MIDNIGHT MDT TONIGHT FOR COZ060. && $$ SHORT TERM...PETERSEN LONG TERM...MW AVIATION...PETERSEN
AREA FORECAST DISCUSSION
NWS GRAND JUNCTION CO
1040 AM MDT SAT APR 20 2013 .SHORT TERM...(TODAY THROUGH SUNDAY) ISSUED AT 343 AM MDT SAT APR 20 2013 TODAY...SHORTWAVE AND ASSOCIATED SFC FRONT MAKING QUICK PROGRESS ACROSS THE GREAT BASIN THIS MORNING AND WILL BE PUSHING EAST ACROSS WESTERN COLORADO TODAY. AREAS OF LIGHT RAIN AND SNOW FALLING ACROSS THE REGION WILL PEAK IN AREAL COVERAGE THIS MORNING AS THE MAIN FORCING ASSOCIATED WITH THE PASSING WAVE ARRIVES. RADAR ECHOES HAVE BEEN ON THE INCREASE THIS MORNING AND MORNING HRRR AND RAP MODELS BOTH INDICATING A FAIRLY ACTIVE START TO THE DAY WITH SNOW LEVELS RUNNING AROUND 6K. BEST ACCUMULATIONS LOOKS TO BE CONFINED TO THE HIGHER ELEVATIONS...WITH THE NORTHERN MOUNTAINS REMAINING FAVORED ATTM...WITH CURRENT ADVISORIES ON TRACK. HAVE BOOSTED POPS AND SHAVED TEMPS A BIT FROM MOS VALUES. TONIGHT...THOUGH DYNAMICAL SUPPORT HAS SHIFTED EAST SNOW WILL CONTINUE ACROSS NW COLORADO WITH FORECAST SOUNDINGS INDICATING A MOIST NW OROGRAPHIC FLOW THROUGH MIDNIGHT. THEN THE FLOW SLACKENS SOMEWHAT AND BACKS TO SW. THE MOIST LAYER ALSO SHRINKS TO BELOW 12KFT FOR LITTLE TO NO ACCUMULATING SNOWFALL. TEMPERATURES STAY NEAR NORMAL NORTH UNDER CLOUD COVER...ABOUT 5 DEGREES BELOW NORMAL FOR THE CENTRAL AND SOUTH UNDER MOSTLY CLEAR SKIES. SUNDAY...WEST WINDS INCREASE AS THE NEXT OPEN WAVE WORKS IN FROM THE NW. THE JET REMAINS ORIENTED NEAR THE CO-WY BORDER EFFECTIVELY KEEPING THE COLD AIR AND DYNAMICS NORTH OF THIS FORECAST AREA. AFTERNOON HEATING AND MARGINAL MOISTURE PRODUCE A SLIVER OF AFTERNOON CAPE MAINLY IN THE NW CO MTNS FOR SCATTERED SNOW SHOWERS. SNOW LEVEL WILL BE AROUND 8KFT NORTH TO 9KFT CENTRAL. .LONG TERM...(SUNDAY NIGHT THROUGH FRIDAY) ISSUED AT 343 AM MDT SAT APR 20 2013 SUNDAY NIGHT-MONDAY NIGHT...ENHANCING ENERGY DEVELOPS A TROUGH AND BEGINS TO PUSH THE JET AND ASSOCIATED COLD FRONT NW-SE THROUGH THE REGION. THE BEST DYNAMICAL SUPPORT SHIFTS EAST OF THE CONTINENTAL DIVIDE WITH SNOW ACCUMULATIONS NOW LOOKING MEAGER EXCEPT ALONG THE COLORADO SPINE WHERE A CONVECTIVE COMPONENT MAY PRODUCE LOCALIZED ENHANCED SNOW ACCUMULATIONS. BREEZY TO WINDY CONDITIONS CONTINUE ON MONDAY AS THE COLD FRONT WORKS THROUGH THE REGION WITH A COOLER DRIER AIR MASS WORKING IN OVERNIGHT. TUESDAY THROUGH FRIDAY...EXITING WAVE WILL CLIP THE NORTHERN AND CENTRAL MOUNTAINS WITH BRIEF PERIOD OF SNOWFALL ON TUESDAY. THE ECMWF REMAINS A BIT STRONGER WITH THIS WAVE...WHICH WOULD RESULT IN A BIT MORE ACTIVITY ACROSS THE FORECAST AREA. WILL SPLIT THE DIFFERENCE AND KEEP HIGHER POPS CONFINED TO THE NORTHERN AND CENTRAL MOUNTAINS. YET ANOTHER VERY WEAK SYSTEM BRUSHES BY ON WEDNESDAY...BRINGING A SLIGHT CHANCE FOR HIGH MOUNTAIN SNOW SHOWERS...OTHERWISE A DRY PERIOD IN STORE FROM TUESDAY NIGHT THROUGH EARLY FRIDAY. THE GFS AND EC BOTH DRIVE ANOTHER SYSTEM DOWN THE SPINE OF THE ROCKIES TO CLOSE OUT THE WEEK. THIS WOULD BRING ANOTHER GLANCING SHOT OF PRECIPITATION TO THE AREA...GENERALLY CONFINED TO THE NORTHERN ZONES. TEMPERATURES WILL BE MODERATING A BIT THROUGH THE PERIOD...WITH READINGS CLIMBING TO THE PLUS SIDE OF NORMAL AS WE CLOSE OUT THE WEEK. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON) ISSUED AT 1040 AM MDT SAT APR 20 2013 RAIN AND MOUNTAIN SNOW SHOWERS WILL CONTINUE OVER MUCH OF NORTHERN AND CENTRAL CO AND THE SAN JUAN MOUNTAINS...WITH ISOLATED PRECIPITATION OVER NE UTAH. MOST MOUNTAIN RANGES AND HIGH MOUNTAIN PASSES WILL BE OBSCURED THROUGH THIS EVENING. SLOW IMPROVEMENT WILL BEGIN BY 00Z THIS AFTERNOON WITH MORES STEADILY IMPROVING CONDITIONS OVERNIGHT THROUGH SUNDAY. THROUGH THIS EVENING KASE... KEGE...KRIL...KCAG...AND KHDN CAN EXPECT MVFR CIGS AND OCCASIONAL MVFR VSBY IN PRECIP...WITH BRIEF PERIODS OF IFR CIGS AND VSBYS IN STRONGER SHOWERS. && .GJT WATCHES/WARNINGS/ADVISORIES... CO...WINTER WEATHER ADVISORY UNTIL MIDNIGHT MDT TONIGHT FOR COZ004- 010-013. UT...NONE. && $$ SHORT TERM...JDC LONG TERM...JOE AVIATION...CC
AREA FORECAST DISCUSSION
NWS MIAMI FL
217 PM EDT SAT APR 20 2013 .DISCUSSION... SATURDAY THROUGH MONDAY... IN THE SHORT TERM FOR THIS AFTERNOON AND EVENING THERE IS NOT MUCH CHANGE FROM THE PREVIOUS THINKING. THE SHOWERS AND THUNDERSTORMS OVER THE ATLANTIC WATERS HAVE DIMINISHED IN COVERAGE BUT A FEW SHOWERS ARE BEGINNING TO DEVELOP ALONG THE SEA BREEZE EXTENDING FROM SOUTH MIAMI-DADE TO COASTAL PALM BEACH COUNTY AS WELL AS WEST OF LAKE OKEECHOBEE ASSOCIATED WITH THE FRONT ITSELF. THIS PATTERN IS CONSISTENT WITH THE FORECAST OF HIGH RESOLUTION MODELS FOR THIS AFTERNOON AND EVENING. FAVORING FACTORS FOR THE FORMATION OF SHOWERS AND THUNDERSTORMS ALONG THE EAST COAST ARE: THE WEAK SOUTHWESTERLY FLOW AND THE TROUGH OF LOW PRESSURE NEAR THE FLORIDA EAST COAST. THE LIMITING FACTORS ARE THE WARM 500 MB TEMPERATURES AND THE CAP AROUND 15KFT. IT IS POSSIBLE THAT ONCE THE ACTIVITY ALONG THE SEA BREEZE REACHES THE CAP IT COULD DIMINISH IN INTENSITY BUT STILL PRODUCE HEAVY RAINS, GUSTY WINDS, AND LIGHTNING. IN OTHER WORDS, IT COULD START ACTIVE IN THE NEXT FEW HOURS AND THEN WEAKEN A BIT AS THE STORMS START REACHING THE CAP. THE ADVANCE OF THE FRONT IS ALSO A FAVORABLE FACTOR THAT IT COULD BECOME MORE IMPORTANT AS THE DAY PROGRESSES. THE STEERING FLOW WILL MOVE STORMS GENERALLY FROM WEST TO EAST. THIS WILL INCREASE THE POTENTIAL FOR THUNDERSTORMS FOR THE EAST COAST. THE CURRENT 500 MB PATTERN SHOWS A TROUGH OF LOW PRESSURE OVER THE EASTERN AND CENTRAL US AND A STRONG BLOCKING RIDGE OF HIGH PRESSURE OVER THE WESTERN ATLANTIC. AS THE HIGH CONTINUES TO MOVE FURTHER EAST COOLER 500 MB TEMPERATURES WILL SPREAD OVER SOUTH FLORIDA ON SUNDAY. THIS IS EXPECTED TO INCREASE THE POTENTIAL FOR STRONG OR EVEN SEVERE STORMS ON SUNDAY IF HEATING IS FAVORABLE. LONG TERM /TUESDAY THROUGH FRIDAY/... BEHIND THE SURFACE TROUGH...A MORE TYPICAL SPRING WEATHER REGIME WILL TAKE HOLD OVER FLORIDA...WITH EASTERLY LOW-LEVEL FLOW AND HIGH PRESSURE BUILDING BOTH NEAR SURFACE AND ALOFT. ISOLATED MAINLY DIURNAL SHOWERS ARE EXPECTED...WITH PARTLY TO MOSTLY SUNNY SKIES AND TEMPERATURES REMAINING SLIGHTLY ABOVE AVERAGE. && .AVIATION...ISSUED AT 147 PM EDT SAT APR 20 2013... SHOWERS AND THUNDERSTORMS ARE BEGINNING TO SAG INTO THE NORTHWEST INTERIOR AREAS. WITH AN ESTABLISHED GULF COAST SEA BREEZE...THIS ACTIVITY SHOULD CONTINUE TO PUSH TO THE EAST. ADDITIONAL CONVECTION WILL ALSO BE POSSIBLE ACROSS THE EAST COAST TERMINALS OVER THE NEXT FEW HOURS OF PEAK HEATING. KEPT TEMPO GROUPS AT ALL EAST COAST SITES FROM 20Z-23Z. WILL AMEND IF NECESSARY. && MARINE... LONG-FUSED ADVISORIES AND WARNINGS ARE NOT EXPECTED THIS WEEKEND OR NEXT WEEK OVER THE WATERS. LOCALLY HIGH WAVES AND WINDS CAN BE EXPECTED IN SCATTERED TO NUMEROUS THUNDERSTORMS TODAY THROUGH MONDAY...AND SPECIAL MARINE WARNINGS MAY BE ISSUED FROM TIME TO TIME. && FIRE WEATHER... MINIMUM RELATIVE HUMIDITY VALUES WILL BE ABOVE 50 PERCENT THIS WEEKEND AND EARLY NEXT WEEK...AS MOIST ATMOSPHERE CONTRIBUTES TO SCATTERED TO NUMEROUS SHOWERS AND THUNDERSTORMS. WINDS WILL MAINLY SOUTH TODAY...BUT TRANSITION TO THE NORTHEAST TONIGHT AS COLD FRONT MOVES IN. LOW WIND SPEEDS ARE EXPECTED OUTSIDE OF SHOWERS AND THUNDERSTORMS. && .PREV DISCUSSION... /ISSUED 947 AM EDT SAT APR 20 2013/ UPDATE... SHOWERS AND THUNDERSTORMS OVER THE ATLANTIC WATERS HAVE DEVELOPED THIS MORNING DUE TO THE CONVERGENCE OF SE FLOW OVER THE BAHAMAS AND MORE SOUTHERLY FLOW OVER SOUTH FLORIDA. THE 12Z SOUNDING FROM THIS MORNING SHOWS A CAP AROUND 650 MB ASSOCIATED WITH THE SUBTROPICAL HIGH PRESSURE OVER THE ATLANTIC AND THE GULF. 500 MB TEMPERATURES ARE AROUND -6C AND ARE NOT EXPECTED TO COOL BEYOND -7C THIS AFTERNOON. HOWEVER, THE INFLUENCE OF A COLD FRONT MOVING SOUTHWARD IS EXPECTED TO INTERACT WITH A WEAK EAST COAST SEA BREEZE TO TRIGGER SHOWERS AND THUNDERSTORMS, ESPECIALLY IN PALM BEACH AND BROWARD COUNTIES. SOME STORMS CAN ALSO EXTEND INTO MIAMI-DADE. FOR THE WEST COAST THERE IS ONLY A SMALL CHANCE OF THUNDERSTORMS, SINCE MOST OF THE SURFACE TROUGH IS ALIGNED FROM NORTHEAST TO SOUTHWEST OVER THE ATLANTIC WATERS. AS MENTIONED IN THE PREVIOUS DISCUSSION THE UPPER LEVEL TEMPERATURES ARE FORECAST TO COOL ON SUNDAY ALLOWING FOR A GREATER CHANCE OF THUNDERSTORMS THAN TODAY. FOR TODAY THE HIGHEST POPS ARE STILL INCLUDED FOR PALM BEACH AND BROWARD. PREV DISCUSSION... /ISSUED 725 AM EDT SAT APR 20 2013/ AVIATION... MOSTLY VFR CONDITIONS WILL OCCUR EARLY IN THE FORECAST ALTHOUGH THERE COULD BE A BRIEF MVFR CIG AS A FEW SHOWERS MOVE ACROSS SOUTH FLORIDA. SCATTERED TO NUMEROUS SHOWERS AND THUNDERSTORMS ARE EXPECTED TO DEVELOP BY THIS AFTERNOON AHEAD OF A WEAKENING COLD FRONT THAT WILL SAG ACROSS THE REGION. THE HRRR INDICATES CONVECTION TO BEGIN DEVELOPING IN EARNEST BETWEEN 18-20Z WITH THE STEERING FLOW TAKING THE STORMS TO THE EAST COAST. THEREFORE, HAVE LEFT TEMPO 18-22Z FOR ALL EAST TERMINALS WITH SOME OF THE ACTIVITY POSSIBLY PERSISTING BEYOND THIS TIME FRAME. SURFACE WINDS ARE QUESTIONABLE WITH A SLOW MOVING FRONTAL BOUNDARY BUT GENERALLY SSW-SSE AHEAD OF THE FRONT AND NE BEHIND THE FRONT. && .PRELIMINARY POINT TEMPS/POPS... WEST PALM BEACH 73 84 70 83 / 40 60 40 60 FORT LAUDERDALE 74 85 72 84 / 30 60 40 60 MIAMI 75 86 73 85 / 30 50 40 60 NAPLES 69 86 70 84 / 20 40 40 50 && .MFL WATCHES/WARNINGS/ADVISORIES... FL...NONE. AM...NONE. GM...NONE. && $$ DISCUSSION/MARINE/FIRE...71/JE AVIATION/RADAR...10/CD
AREA FORECAST DISCUSSION
NWS MIAMI FL
147 PM EDT SAT APR 20 2013 .AVIATION... SHOWERS AND THUNDERSTORMS ARE BEGINNING TO SAG INTO THE NORTHWEST INTERIOR AREAS. WITH AN ESTABLISHED GULF COAST SEA BREEZE...THIS ACTIVITY SHOULD CONTINUE TO PUSH TO THE EAST. ADDITIONAL CONVECTION WILL ALSO BE POSSIBLE ACROSS THE EAST COAST TERMINALS OVER THE NEXT FEW HOURS OF PEAK HEATING. KEPT TEMPO GROUPS AT ALL EAST COAST SITES FROM 20Z-23Z. WILL AMEND IF NECESSARY. && .PREV DISCUSSION... /ISSUED 947 AM EDT SAT APR 20 2013/ UPDATE... SHOWERS AND THUNDERSTORMS OVER THE ATLANTIC WATERS HAVE DEVELOPED THIS MORNING DUE TO THE CONVERGENCE OF SE FLOW OVER THE BAHAMAS AND MORE SOUTHERLY FLOW OVER SOUTH FLORIDA. THE 12Z SOUNDING FROM THIS MORNING SHOWS A CAP AROUND 650 MB ASSOCIATED WITH THE SUBTROPICAL HIGH PRESSURE OVER THE ATLANTIC AND THE GULF. 500 MB TEMPERATURES ARE AROUND -6C AND ARE NOT EXPECTED TO COOL BEYOND -7C THIS AFTERNOON. HOWEVER, THE INFLUENCE OF A COLD FRONT MOVING SOUTHWARD IS EXPECTED TO INTERACT WITH A WEAK EAST COAST SEA BREEZE TO TRIGGER SHOWERS AND THUNDERSTORMS, ESPECIALLY IN PALM BEACH AND BROWARD COUNTIES. SOME STORMS CAN ALSO EXTEND INTO MIAMI-DADE. FOR THE WEST COAST THERE IS ONLY A SMALL CHANCE OF THUNDERSTORMS, SINCE MOST OF THE SURFACE TROUGH IS ALIGNED FROM NORTHEAST TO SOUTHWEST OVER THE ATLANTIC WATERS. AS MENTIONED IN THE PREVIOUS DISCUSSION THE UPPER LEVEL TEMPERATURES ARE FORECAST TO COOL ON SUNDAY ALLOWING FOR A GREATER CHANCE OF THUNDERSTORMS THAN TODAY. FOR TODAY THE HIGHEST POPS ARE STILL INCLUDED FOR PALM BEACH AND BROWARD. PREV DISCUSSION... /ISSUED 725 AM EDT SAT APR 20 2013/ AVIATION... MOSTLY VFR CONDITIONS WILL OCCUR EARLY IN THE FORECAST ALTHOUGH THERE COULD BE A BRIEF MVFR CIG AS A FEW SHOWERS MOVE ACROSS SOUTH FLORIDA. SCATTERED TO NUMEROUS SHOWERS AND THUNDERSTORMS ARE EXPECTED TO DEVELOP BY THIS AFTERNOON AHEAD OF A WEAKENING COLD FRONT THAT WILL SAG ACROSS THE REGION. THE HRRR INDICATES CONVECTION TO BEGIN DEVELOPING IN EARNEST BETWEEN 18-20Z WITH THE STEERING FLOW TAKING THE STORMS TO THE EAST COAST. THEREFORE, HAVE LEFT TEMPO 18-22Z FOR ALL EAST TERMINALS WITH SOME OF THE ACTIVITY POSSIBLY PERSISTING BEYOND THIS TIME FRAME. SURFACE WINDS ARE QUESTIONABLE WITH A SLOW MOVING FRONTAL BOUNDARY BUT GENERALLY SSW-SSE AHEAD OF THE FRONT AND NE BEHIND THE FRONT. && .PRELIMINARY POINT TEMPS/POPS... WEST PALM BEACH 71 83 72 84 / 40 60 40 60 FORT LAUDERDALE 75 84 74 85 / 30 60 40 60 MIAMI 73 85 73 85 / 30 50 40 60 NAPLES 69 86 69 87 / 20 40 40 50 && .MFL WATCHES/WARNINGS/ADVISORIES... FL...NONE. AM...NONE. GM...NONE. && $$ DISCUSSION/MARINE/FIRE...71/JE AVIATION/RADAR...10/CD
AREA FORECAST DISCUSSION
NWS CHARLESTON SC
632 PM EDT SAT APR 20 2013 .SYNOPSIS... A STATIONARY FRONT WILL LINGER OFF THE SOUTHEAST COAST INTO EARLY NEXT WEEK...AS HIGH PRESSURE BUILDS FROM THE NORTH. A COLD FRONT WILL MOVE ACROSS THE AREA WEDNESDAY OR THURSDAY...FOLLOWED BY HIGH PRESSURE LATE IN THE WEEK. && .NEAR TERM /UNTIL 6 AM SUNDAY MORNING/... EARLY SATURDAY EVENING...BACK EDGE OF MID/HIGH LEVEL CLOUD SHIELD CONTINUED TO STREAM OVER COASTAL COUNTIES BUT WAS POISED TO ADVANCE OFFSHORE...LEAVING MAINLY CLEAR SKIES ONLY PUNCTUATED BY ADDITIONAL CIRRUS PUSHING INTO THE REGION FROM THE WEST OVERNIGHT. ONGOING FORECASTS REMAINED IN DECENT SHAPE AND REQUIRED ONLY MINOR ADJUSTMENTS TO HOUR;LY PARAMETERS THIS EVENING. LARGE HIGH PRES WL MOVE INTO THE OHIO VALLEY TNGT WHILE XTNDG WELL TO THE S. RAP FCST SOUNDINGS SUGGEST THE BNDRY LYR WL GRADUALLY DECOUPLE THIS EVNG EVENTUALLY YIELDING A LIGHT/CALM WND REGIME. THIS COUPLED WITH CLR SKIES AND LOW DEWPTS WL SUPPORT A DECENT RADIATIONAL SETUP WITH LOWS DROPPING INTO THE LWR 40S INLAND TO THE LWR-MID 50S AT THE BEACHES WHERE WNDS WL LIKELY STAY UP A BIT. IT IS NOT OUT OF THE REALM OF POSSIBILITY THAT A FEW UPR 30S COULD OCCUR IN SOME OF THE NORMALLY COLDER LOCATIONS SUCH AS ALLENDALE AND JAMESTOWN. 20/12Z GFS-COOP GUIDANCE IS FCSTG UPR 30S IN SEVERAL OF THE FAR INLAND STATIONS. FROST IS NOT A CONCERN EVEN IF UPR 30S WHERE TO OCCUR. && .SHORT TERM /6 AM SUNDAY MORNING THROUGH TUESDAY/... SUNDAY...A COLD FRONT WILL STALL WELL OFF THE SOUTHEAST COAST SUNDAY WHILE LARGE SFC HIGH PRESSURE BECOMES CENTERED OVER THE NORTHEASTERN UNITED STATES. THIS WILL RESULT IN UNSEASONABLY COOL CONDITIONS OVER THE SOUTHEASTERN UNITED STATES AS BRISK NORTHEAST WINDS DEVELOP IN RESPONSE TO A TIGHT PRESSURE GRADIENT BETWEEN THE STALLED BOUNDARY AND HIGH PRESSURE TO THE NORTH. WE COULD SEE A PERIOD OF GUSTY WINDS BETWEEN 25-30 MPH SUNDAY AFTERNOON AS TEMPS APPROACH THE UPPER 60S TO AROUND 70...BUT CONDITIONS SHOULD FALL SHORT OF WIND ADVISORY CRITERIA. CHANCES OF RAIN/SHOWERS WILL THEN INCREASE ALONG COASTAL COUNTIES THROUGH SUNDAY EVENING AS ISENTROPIC ASCENT AND LOW LVL MOISTURE INCREASE OVER THE AREA IN RESPONSE TO LOW PRESSURE DEVELOPING ALONG THE STALLED BOUNDARY OFFSHORE. HAVE MAINTAINED THE CURRENT PRECIP FORECAST WITH A SLIGHT CHANCE OF SHOWERS INLAND AND CHANCE OF SHOWERS ALONG COASTAL COUNTIES. MONDAY AND TUESDAY...CLOUDY AND COOL CONDITIONS WILL LIKELY PERSIST INTO EARLY NEXT WEEK AS MOISTURE LINGERS ALONG THE WESTERN EDGE OF LOW PRESSURE DEEPENING ALONG THE SOUTHEAST COAST AND HIGH PRESSURE WEDGING OVER LAND. A SLIGHT CHANCE OF RAIN/SHOWERS AND GUSTY WINDS WILL BE POSSIBLE ON MONDAY...MAINLY ALONG COASTAL COUNTIES WHERE MOISTURE IS GREATEST AND THE PRESSURE GRADIENT REMAINS PINCHED BETWEEN THE DEPARTING LOW TO THE NORTHEAST AND HIGH PRESSURE OVER LAND. BY TUESDAY...CONDITIONS WILL GRADUALLY WARM AND DRY UNDER ZONAL FLOW WHILE SFC HIGH PRESSURE SLIDES TO THE COAST AND THE OFFSHORE LOW SHIFTS FURTHER NORTH AND EAST AWAY FROM THE REGION. OVERALL HIGH TEMPS SHOULD REACH THE UPPER 60S TO AROUND 70 ON MONDAY...BEFORE WARMING INTO THE LOW 70S ON TUESDAY. LAKE WINDS...STRONG NORTHEAST WINDS ARE EXPECTED SUNDAY AFTERNOON AND SUNDAY NIGHT AS HIGH PRESSURE BUILDS FROM THE NORTH AND TEMPERATURES PROFILES BECOME FAVORABLE FOR MIXING OF STRONG LOW-LEVEL WINDS DOWN OVER THE RELATIVELY WARMER LAKE WATERS. THUS...A LAKE WIND ADVISORY MAY BE NEEDED DURING THIS TIME. && .LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/... HIGH PRESSURE WILL BE SLIPPING OFFSHORE TUESDAY NIGHT INTO WEDNESDAY AS A COLD FRONT APPROACHES FROM THE WEST. THERE IS STILL SOME UNCERTAINTY REGARDING THE TIMING OF THE COLD FRONTAL PASSAGE WEDNESDAY OR THURSDAY...AND IT COULD EVEN STALL OUT OVER OR NEAR THE AREA. FOR NOW WE HAVE KEPT RAIN CHANCES LOW AND MAINLY THROUGH THURSDAY WITH DRIER CONDITIONS FRIDAY. RAIN CHANCES COULD INCREASE AGAIN LATER SATURDAY AS ANOTHER COLD FRONT BEGINS TO APPROACH FROM THE WEST. TEMPERATURES ARE TRICKY AS MUCH DEPENDS ON THE TIMING OF THE FRONTAL PASSAGE BUT FOR NOW HAVE KEPT THEM NEAR TO BELOW NORMAL. && .AVIATION /00Z SUNDAY THROUGH THURSDAY/... VFR IS EXPECTED TO PREVAIL THROUGH THE VALID TAF PERIOD. CLOUDS WILL CONTINUE TO SHIFT EAST...WITH CLEAR SKIES EXPECTED TONIGHT. MAIN AVIATION CONCERN WILL BE THE WINDS TOMORROW. A TIGHTENED PRESSURE GRADIENT WILL RESULT IN GUSTY WINDS DEVELOPING LATE MORNING. GENERALLY EXPECT NORTHEAST WINDS SUSTAINED AROUND 15 KTS...WITH GUSTS UP TO AROUND 23 KTS. EXTENDED AVIATION OUTLOOK....MVFR CIGS EXPECTED BY SUNDAY EVENING AND COULD POSSIBLY LAST INTO EARLY TUESDAY. BREEZY/GUSTY CONDITIONS EXPECTED SUNDAY AND MONDAY. && .MARINE... TONIGHT...N WNDS WL GRADLY VEER TO THE NE AS HIGH PRES BUILDS IN FROM THE S. SPEEDS WL BEGIN TO STEADILY INCR AFT MIDNGT AS THE PRES GRADIENT BETWEEN HIGH PRES TO THE N AND THE REMNANT CDFNT DEGENERATES INTO A SHARPENING COASTAL TROUGH. XPCT NE WINDS OF 15-20 KT TO DOMINATE NEARSHORE WTRS AND 20-25 KT OFFSHORE WTRS BY SUNRISE SUN. SEAS WL BUILD IN RESPONSE TO THE STRENGTHENING WINDS...BUILDING TO 3-5 FT NEARSHORE WATERS EDISTO BEACH S...4-6 FT FOR THE CHARLESTON COUNTY COASTAL WATERS AND 5-7 FT OFFSHORE WATERS. WL HOIST A SMALL CRAFT ADVISORY FOR THE GEORGIA OFFSHORE LEG BEGINNING AND MIDNIGHT AND THE CHARLESTON COUNTY WATERS BEGINNING A 5 AM SUNDAY. SUNDAY THROUGH THURSDAY...MARINE CONDITIONS WILL DETERIORATE DURING THE BEGINNING OF THE WEEK AS AN ENHANCED PRESSURE GRADIENT DEVELOPS BETWEEN A STALLING COLD FRONT OFFSHORE AND STRONG HIGH PRESSURE BUILDING OVER LAND. STRONG COLD AIR ADVECTION FROM THE NORTH/NORTHWEST ALONG WITH 40-45 KT 1000 MB GEOSTROPHIC WINDS SUGGEST GALE FORCE WIND GUSTS BETWEEN 35-40 KT OVER ALL WATERS SUNDAY AFTERNOON INTO EARLY MONDAY. THE BEST CHANCE OF GALE FORCE WINDS WILL REMAIN OVER WARMER WATER TEMPS IN NORTHERN SC WATERS AND OUTER GEORGIA WATERS. SEAS MAY ALSO APPROACH 10-12 FT BEYOND 10 NM FROM THE COAST SUNDAY NIGHT INTO EARLY MONDAY. CONDITIONS SHOULD DROP BELOW ADVISORY LEVELS FOR MUCH OF THE NEARSHORE WATERS MONDAY NIGHT AND ACROSS THE OUTER WATERS TUESDAY. A COLD FRONT WILL LIKELY PUSH THROUGH THE WATERS WEDNESDAY OR THURSDAY BUT CONDITIONS LOOK TO REMAIN BELOW ADVISORY LEVELS. RIP CURRENTS...THE COMBINATION OF INCREASING WINDS ALONG THE BEACHES AND BUILDING SURF WILL SUPPORT A MODERATE RISK FOR RIP CURRENTS ALONG THE SOUTH CAROLINA BEACHES AND A HIGH RISK FOR THE GEORGIA BEACHES ON SUNDAY. THERE ARE SOME INDICATIONS IN THE LATEST WW4 OUTPUT THAT THE UNDERLYING SWELL PERIOD COULD REACH AS HIGH AS 10 SECONDS. SHOULD THIS VERIFY...THEN THE RISK WOULD TIP INTO THE HIGH CATEGORY FOR THE SOUTH CAROLINA BEACHES AS WELL. AN ENHANCED RISK FOR RIP CURRENTS WILL PERSIST FOR THE NEXT SEVERAL DAYS. && .TIDES/COASTAL FLOODING... STRONG NORTHEAST WINDS SUNDAY AND SUNDAY NIGHT WILL LEAD TO BUILDING SEAS...ROUGH SURF...BEACH EROSION AND SHALLOW COASTAL FLOODING. A COASTAL FLOOD ADVISORY AND HIGH SURF ADVISORY MAY EVENTUALLY BE NEEDED. && .CHS WATCHES/WARNINGS/ADVISORIES... GA...HIGH RISK FOR RIP CURRENTS FROM SUNDAY MORNING THROUGH SUNDAY EVENING FOR GAZ117-119-139-141. SC...NONE. MARINE...GALE WATCH FROM SUNDAY MORNING THROUGH MONDAY MORNING FOR AMZ330-352-354. GALE WATCH FROM SUNDAY MORNING THROUGH MONDAY AFTERNOON FOR AMZ350-374. SMALL CRAFT ADVISORY FROM 5 AM TO 11 AM EDT SUNDAY FOR AMZ350. SMALL CRAFT ADVISORY FROM MIDNIGHT TONIGHT TO 11 AM EDT SUNDAY FOR AMZ374. && $$ SYNOPSIS... NEAR TERM...SPR/ST SHORT TERM...DPB LONG TERM...RJB AVIATION...SPR MARINE...SPR/DPB/ST TIDES/COASTAL FLOODING...
AREA FORECAST DISCUSSION
NWS CHARLESTON SC
309 PM EDT SAT APR 20 2013 ...HIGH RISK FOR RIP CURRENTS ALONG THE BEACHES OF NORTH COASTAL GEORGIA SUNDAY... .SYNOPSIS... A COLD FRONT WILL STALL OFF THE SOUTHEAST COAST AND LINGER INTO EARLY NEXT WEEK...AS HIGH PRESSURE BUILDS FROM THE NORTH. ANOTHER COLD FRONT WILL MOVE ACROSS THE AREA WEDNESDAY OR THURSDAY...FOLLOWED BY HIGH PRESSURE LATE IN THE WEEK. && .NEAR TERM /THROUGH TONIGHT/... THE BACK EDGE OF THE CLRG LINE WL CONT TO MOVE SLOWLY E FOR THE REMAINDER OF THE AFTN HRS WITH MAINLY CLR SKIES XPCTD TO DOMINATE FOR THE OVRNGT PERIOD. LARGE HIGH PRES WL MOVE INTO THE OHIO VALLEY TNGT WHILE XTNDG WELL TO THE S. RAP FCST SOUNDINGS SUGGEST THE BNDRY LYR WL GRADLY DECOUPLE THIS EVNG EVENTUALLY YIELDING A LIGHT/CALM WND REGIME. THIS COUPLED WITH CLR SKIES AND LOW DEWPTS WL SUPPORT A DECENT RADIATIONAL SETUP WITH LOWS DROPPING INTO THE LWR 40S INLAND TO THE LWR-MID 50S AT THE BEACHES WHERE WNDS WL LIKELY STAY UP A BIT. IT IS NOT OUT OF THE REALM OF POSSIBILITY THAT A FEW UPR 30S COULD OCCUR IN SOME OF THE NORMALLY COLDER LOCATIONS SUCH AS ALLENDALE AND JAMESTOWN. 20/12Z GFS-COOP GUIDANCE IS FCSTG UPR 30S IN SEVERAL OF THE FAR INLAND STATIONS. FROST IS NOT A CONCERN EVEN IF UPR 30S WHERE TO OCCUR. && .SHORT TERM /SUNDAY THROUGH TUESDAY/... SUNDAY...A COLD FRONT WILL STALL WELL OFF THE SOUTHEAST COAST SUNDAY WHILE LARGE SFC HIGH PRESSURE BECOMES CENTERED OVER THE NORTHEASTERN UNITED STATES. THIS WILL RESULT IN UNSEASONABLY COOL CONDITIONS OVER THE SOUTHEASTERN UNITED STATES AS BRISK NORTHEAST WINDS DEVELOP IN RESPONSE TO A TIGHT PRESSURE GRADIENT BETWEEN THE STALLED BOUNDARY AND HIGH PRESSURE TO THE NORTH. WE COULD SEE A PERIOD OF GUSTY WINDS BETWEEN 25-30 MPH SUNDAY AFTERNOON AS TEMPS APPROACH THE UPPER 60S TO AROUND 70...BUT CONDITIONS SHOULD FALL SHORT OF WIND ADVISORY CRITERIA. CHANCES OF RAIN/SHOWERS WILL THEN INCREASE ALONG COASTAL COUNTIES THROUGH SUNDAY EVENING AS ISENTROPIC ASCENT AND LOW LVL MOISTURE INCREASE OVER THE AREA IN RESPONSE TO LOW PRESSURE DEVELOPING ALONG THE STALLED BOUNDARY OFFSHORE. HAVE MAINTAINED THE CURRENT PRECIP FORECAST WITH A SLIGHT CHANCE OF SHOWERS INLAND AND CHANCE OF SHOWERS ALONG COASTAL COUNTIES. MONDAY AND TUESDAY...CLOUDY AND COOL CONDITIONS WILL LIKELY PERSIST INTO EARLY NEXT WEEK AS MOISTURE LINGERS ALONG THE WESTERN EDGE OF LOW PRESSURE DEEPENING ALONG THE SOUTHEAST COAST AND HIGH PRESSURE WEDGING OVER LAND. A SLIGHT CHANCE OF RAIN/SHOWERS AND GUSTY WINDS WILL BE POSSIBLE ON MONDAY...MAINLY ALONG COASTAL COUNTIES WHERE MOISTURE IS GREATEST AND THE PRESSURE GRADIENT REMAINS PINCHED BETWEEN THE DEPARTING LOW TO THE NORTHEAST AND HIGH PRESSURE OVER LAND. BY TUESDAY...CONDITIONS WILL GRADUALLY WARM AND DRY UNDER ZONAL FLOW WHILE SFC HIGH PRESSURE SLIDES TO THE COAST AND THE OFFSHORE LOW SHIFTS FURTHER NORTH AND EAST AWAY FROM THE REGION. OVERALL HIGH TEMPS SHOULD REACH THE UPPER 60S TO AROUND 70 ON MONDAY...BEFORE WARMING INTO THE LOW 70S ON TUESDAY. LAKE WINDS...STRONG NORTHEAST WINDS ARE EXPECTED SUNDAY AFTERNOON AND SUNDAY NIGHT AS HIGH PRESSURE BUILDS FROM THE NORTH AND TEMPERATURES PROFILES BECOME FAVORABLE FOR MIXING OF STRONG LOW-LEVEL WINDS DOWN OVER THE RELATIVELY WARMER LAKE WATERS. THUS...A LAKE WIND ADVISORY MAY BE NEEDED DURING THIS TIME. && .LONG TERM /TUESDAY NIGHT THROUGH FRIDAY/... HIGH PRESSURE WILL BE SLIPPING OFFSHORE TUESDAY NIGHT INTO WEDNESDAY AS A COLD FRONT APPROACHES FROM THE WEST. THERE IS STILL SOME UNCERTAINTY REGARDING THE TIMING OF THE COLD FRONTAL PASSAGE WEDNESDAY OR THURSDAY...AND IT COULD EVEN STALL OUT OVER OR NEAR THE AREA. FOR NOW WE HAVE KEPT RAIN CHANCES LOW AND MAINLY THROUGH THURSDAY WITH DRIER CONDITIONS FRIDAY. RAIN CHANCES COULD INCREASE AGAIN LATER SATURDAY AS ANOTHER COLD FRONT BEGINS TO APPROACH FROM THE WEST. TEMPERATURES ARE TRICKY AS MUCH DEPENDS ON THE TIMING OF THE FRONTAL PASSAGE BUT FOR NOW HAVE KEPT THEM NEAR TO BELOW NORMAL. && .AVIATION /18Z SATURDAY THROUGH THURSDAY/... VFR IS EXPECTED TO PREVAIL THROUGH THE VALID TAF PERIOD. CLOUDS WILL CONTINUE TO SHIFT EAST...WITH CLEAR SKIES EXPECTED TONIGHT. MAIN AVIATION CONCERN WILL BE THE WINDS TOMORROW. A TIGHTENED PRESSURE GRADIENT WILL RESULT IN GUSTY WINDS DEVELOPING LATE MORNING. GENERALLY EXPECT NORTHEAST WINDS SUSTAINED AROUND 15 KTS...WITH GUSTS UP TO AROUND 23 KTS. EXTENDED AVIATION OUTLOOK....MVFR CIGS EXPECTED BY SUNDAY EVENING AND COULD POSSIBLY LAST INTO EARLY TUESDAY. BREEZY/GUSTY CONDITIONS EXPECTED SUNDAY AND MONDAY. && .MARINE... TONIGHT...N WNDS WL GRADLY VEER TO THE NE AS HIGH PRES BUILDS IN FROM THE S. SPEEDS WL BEGIN TO STEADILY INCR AFT MIDNGT AS THE PRES GRADIENT BETWEEN HIGH PRES TO THE N AND THE REMNANT CDFNT DEGENERATES INTO A SHARPENING COASTAL TROUGH. XPCT NE WINDS OF 15-20 KT TO DOMINATE NEARSHORE WTRS AND 20-25 KT OFFSHORE WTRS BY SUNRISE SUN. SEAS WL BUILD IN RESPONSE TO THE STRENGTHENING WINDS...BUILDING TO 3-5 FT NEARSHORE WATERS EDISTO BEACH S...4-6 FT FOR THE CHARLESTON COUNTY COASTAL WATERS AND 5-7 FT OFFSHORE WATERS. WL HOIST A SMALL CRAFT ADVISORY FOR THE GEORGIA OFFSHORE LEG BEGINNING AND MIDNIGHT AND THE CHARLESTON COUNTY WATERS BEGINNING A 5 AM SUNDAY. SUNDAY THROUGH THURSDAY...MARINE CONDITIONS WILL DETERIORATE DURING THE BEGINNING OF THE WEEK AS AN ENHANCED PRESSURE GRADIENT DEVELOPS BETWEEN A STALLING COLD FRONT OFFSHORE AND STRONG HIGH PRESSURE BUILDING OVER LAND. STRONG COLD AIR ADVECTION FROM THE NORTH/NORTHWEST ALONG WITH 40-45 KT 1000 MB GEOSTROPHIC WINDS SUGGEST GALE FORCE WIND GUSTS BETWEEN 35-40 KT OVER ALL WATERS SUNDAY AFTERNOON INTO EARLY MONDAY. THE BEST CHANCE OF GALE FORCE WINDS WILL REMAIN OVER WARMER WATER TEMPS IN NORTHERN SC WATERS AND OUTER GEORGIA WATERS. SEAS MAY ALSO APPROACH 10-12 FT BEYOND 10 NM FROM THE COAST SUNDAY NIGHT INTO EARLY MONDAY. CONDITIONS SHOULD DROP BELOW ADVISORY LEVELS FOR MUCH OF THE NEARSHORE WATERS MONDAY NIGHT AND ACROSS THE OUTER WATERS TUESDAY. A COLD FRONT WILL LIKELY PUSH THROUGH THE WATERS WEDNESDAY OR THURSDAY BUT CONDITIONS LOOK TO REMAIN BELOW ADVISORY LEVELS. RIP CURRENTS...THE COMBINATION OF INCREASING WINDS ALONG THE BEACHES AND BUILDING SURF WILL SUPPORT A MODERATE RISK FOR RIP CURRENTS ALONG THE SOUTH CAROLINA BEACHES AND A HIGH RISK FOR THE GEORGIA BEACHES ON SUNDAY. THERE ARE SOME INDICATIONS IN THE LATEST WW4 OUTPUT THAT THE UNDERLYING SWELL PERIOD COULD REACH AS HIGH AS 10 SECONDS. SHOULD THIS VERIFY...THEN THE RISK WOULD TIP INTO THE HIGH CATEGORY FOR THE SOUTH CAROLINA BEACHES AS WELL. AN ENHANCED RISK FOR RIP CURRENTS WILL PERSIST FOR THE NEXT SEVERAL DAYS. && .TIDES/COASTAL FLOODING... STRONG NORTHEAST WINDS SUNDAY AND SUNDAY NIGHT WILL LEAD TO BUILDING SEAS...ROUGH SURF...BEACH EROSION AND SHALLOW COASTAL FLOODING. A COASTAL FLOOD ADVISORY AND HIGH SURF ADVISORY MAY EVENTUALLY BE NEEDED. && .CHS WATCHES/WARNINGS/ADVISORIES... GA...HIGH RISK FOR RIP CURRENTS FROM SUNDAY MORNING THROUGH SUNDAY EVENING FOR GAZ117-119-139-141. SC...NONE. MARINE...GALE WATCH FROM SUNDAY MORNING THROUGH MONDAY MORNING FOR AMZ330-352-354. GALE WATCH FROM SUNDAY MORNING THROUGH MONDAY AFTERNOON FOR AMZ350-374. SMALL CRAFT ADVISORY FROM 5 AM TO 11 AM EDT SUNDAY FOR AMZ350. SMALL CRAFT ADVISORY FROM MIDNIGHT TONIGHT TO 11 AM EDT SUNDAY FOR AMZ374. && $$ ST/DPB/ECT
AREA FORECAST DISCUSSION...UPDATED
NWS COLUMBIA SC
1017 AM EDT SAT APR 20 2013 .SYNOPSIS... THE COLD FRONT THAT HAS MOVED THROUGH THE FORECAST AREA WILL STALL JUST OFF THE COAST TODAY. THE FRONT WILL REMAIN JUST OFFSHORE THROUGH MONDAY. HIGH PRESSURE MOVING INTO THE NORTHEAST STATES WILL RIDGE SOUTHWARD AND INTO THE FORECAST AREA. && .NEAR TERM /UNTIL 6 PM THIS EVENING/... A COLD FRONT PUSHED ACROSS THE FORECAST AREA OVERNIGHT...SHIFTING RAIN SHOWERS OFF THE COAST BY THIS MORNING. LATEST VISIBLE SAT IMAGERY SHOWING LINGERING HIGH CLOUDS ACROSS THE FORECAST AREA WITH CLEARING ACROSS THE WESTERN CAROLINAS. THESE HIGHER CLOUDS WILL SLOWLY SHIFT EAST THROUGH THE DAY AS THE UPPER TROUGH AXIS MOVES EAST ACROSS THE AREA. DRY HIGH PRESSURE CONTINUES TO BUILD INTO THE REGION FROM THE NORTHWEST WITH NORTHERLY SURFACE WINDS PREVAILING IN THE LOWEST 3000 FT. 14Z LAPS AND RUC ANALYSIS SOUNDINGS INDICATE THE SIGNIFICANT DRY AIR THROUGH THE ATMOSPHERIC COLUMN WITH PRECIPITABLE WATER VALUES DOWN TO AROUND 0.3 INCHES. DO NOT EXPECT ANY CUMULUS DEVELOPMENT TODAY WITH THE DRY AIRMASS AND SKIES SHOULD CLEAR FROM WEST TO EAST THROUGH THE DAY. TEMPERATURES MAY BE A BIT COOLER THAN PREVIOUSLY THOUGHT DUE TO LINGERING HIGH CLOUDS...ESPECIALLY ACROSS THE EASTERN PORTIONS OF THE FORECAST AREA. HAVE ADJUSTED MAX TEMPERATURES DOWN A COUPLE OF DEGREES TO BETTER REFLECT THIS. && .SHORT TERM /6 PM THIS EVENING THROUGH SUNDAY NIGHT/... HIGH PRESSURE MOVING INTO THE NORTHEAST STATES WILL RIDGE SOUTHWARD AND INTO THE FORECAST AREA. THE NAM AND GFS KEEP THE AIR MASS DRY THROUGH TONIGHT. MOISTURE APPEARS TO INCREASE WITH A DEVELOPING EASTERLY FLOW WITH WEAK ISENTROPIC LIFT FOR SUNDAY AND SUNDAY NIGHT. THE MODELS KEEP THE MOISTURE SHALLOW AND LIFT WEAK. MAINTAINED JUST CHANCE POPS SUNDAY NIGHT. THE HIGH TEMPERATURE GUIDANCE MAY BE TOO WARM SUNDAY BECAUSE OF A DEVELOPING WEDGE PATTERN. USED THE GUIDANCE CONSENSUS FOR THE LOW TEMPERATURE FORECAST. && .LONG TERM /MONDAY THROUGH FRIDAY/... THE NAM AND GFS SHOW A WEAK WEDGE PATTERN MONDAY. THE MOISTURE STILL APPEARS SHALLOW WITH WEAK ISENTROPIC LIFT. THE NAM AND GFS MOS INDICATE LOW POPS. EXPECT ANY RAIN WILL BE LIGHT. THE TEMPERATURE GUIDANCE APPEARS TOO WARM BECAUSE OF THE WEDGE PATTERN. THE WEDGE PATTERN APPEARS TO FURTHER WEAKEN TUESDAY. THE GFS SHOWS THE NEXT COLD FRONT AFFECTING THE AREA WEDNESDAY INTO THURSDAY SUPPORTING A CHANCE OF SHOWERS AND THUNDERSTORMS. DRYING BEHIND THIS FRONT SHOULD DOMINATE FRIDAY. && .AVIATION /15Z SATURDAY THROUGH WEDNESDAY/... VFR CONDITIONS EXPECTED THROUGH THE 24 HR FORECAST PERIOD. HIGH PRESSURE CONTINUES TO BUILD INTO THE REGION WITH NORTHERLY WINDS THIS MORNING AROUND 10 KNOTS OR SO GRADUALLY DIMINISHING AND SHIFTING MORE NORTHEASTERLY BY 00Z THROUGH THE OVERNIGHT HOURS. VFR HIGH CLOUDS WILL GRADUALLY CLEAR FROM WEST TO EAST THROUGH THE DAY WITH NO AVIATION IMPACTS EXPECTED. EXTENDED AVIATION OUTLOOK...SOME CIG/VSBY RESTRICTIONS POSSIBLE SUNDAY NIGHT INTO MONDAY AS A STALLED FRONT OFF THE ATLANTIC COAST MAY SPREAD CLOUDS AND SOME PRECIPITATION BACK INTO THE AREA. ANOTHER COLD FRONT WILL CROSS AREA WEDNESDAY WITH CIG/VSBY RESTRICTIONS POSSIBLE. && .CAE WATCHES/WARNINGS/ADVISORIES... SC...NONE. GA...NONE. && $$ NEAR TERM...HC AVIATION...HC
AREA FORECAST DISCUSSION
NWS NORTHERN INDIANA
220 PM EDT SAT APR 20 2013 .UPDATE... ISSUED AT 1206 PM EDT SAT APR 20 2013 FAIRLY STRONG NEGATIVE VORTICITY ADVECTION ALOFT IN ASSOCIATION WITH DEPARTING UPPER LEVEL TROUGH WILL AID LARGE SCALE SUBSIDENCE THIS AFTERNOON. LACK OF CU FORMATION NOTED FROM NORTHEAST ILLINOIS INTO FAR NORTHWEST INDIANA IN ASSOCIATION WITH THIS INCREASING SUBSIDENCE SHOULD EVENTUALLY BECOME THE RULE ACROSS THE LOCAL AREA LATE THIS AFTERNOON. LINGERING LAKE EFFECT CLOUDINESS WILL DIMINISH OVER THE NEXT FEW HOURS AS LOW LEVEL FLOW ACROSS SOUTHERN LAKE MICHIGAN BEGINS TO TRANSITION TO MAINLY A DIVERGENT/ONSHORE TYPE. CU APPEARS TO BE FAIRLY THICK AND OF GOOD COVERAGE ACROSS PORTIONS OF EASTERN HALF OF CWA...ALTHOUGH GRADUALLY EXPECTING THIS CU FIELD TO BECOME LESS VERTICALLY DEVELOPED AND THINNER THROUGH TIME. DESPITE MAINTENANCE OF LOW LEVEL THERMAL TROUGH...INCREASED INSOLATION SHOULD SUPPORT HIGHS CLOSE TO THAT OF GOING FORECAST OR PERHAPS JUST SHORT OF THAT IN SOME INSTANCES. WITH GOING FORECAST IN GOOD SHAPE...ONLY MADE SOME MARGINAL TWEAKS TO SKY COVER TO ACCOUNT FOR CURRENT TRENDS...OTHERWISE PREVIOUS FORECAST KEPT INTACT. && .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 352 AM EDT SAT APR 20 2013 SCATTERED SNOW SHOWERS CONTINUE ACROSS THE CWA AT PRESS TIME...AIDED BY PERSISTENT MOIST CYCLONIC FLOW ASSOCIATED WITH PASSING MIDLEVEL TROUGH AXIS. HI-RES FORECAST SOUNDINGS ALSO SHOW BOUNDARY LAYER HAS REMAINED WELL MIXED THROUGH THE OVERNIGHT HOURS...FURTHER SUPPORTING CONVECTIVE SNOW SHOWERS. QUESTION WILL BE WHETHER OR NOT ACTIVITY CAN PERSIST BEYOND 12Z. A FEW PREVIOUS RAP MODEL RUNS SUGGESTED ISOLATED RAIN/SNOW SHOWERS PERSISTING FOR MUCH OF THE MORNING AS ONE LAST RIBBON OF SHEAR VORTICITY ROTATES THROUGH THE AREA. HOWEVER...MIDLEVEL HEIGHTS WILL BE CLIMBING QUICKLY BY LATER THIS MORNING AND NAM BUFR DATA SHOWS LOWER TROPOSPHERIC DRY AIR INCREASING AS WELL AS A STRENGTHENING SUBSIDENCE INVERSION. THEREFORE EXPECT LITTLE MORE THAN ISOLATED FLURRIES AFTER 12Z WITH INCREASINGLY ANTICYCLONIC FLOW BRINGING DRY CONDITIONS EVERYWHERE BY MIDDAY. THERMAL TROUGH WILL BE SHIFTING EAST BY THE AFTERNOON BUT 850MB TEMPS STILL EXPECTED TO BE AROUND -8C DURING PEAK HEATING. MIXING THIS TO THE SURFACE ONLY GIVES HIGHS IN THE LOW 40S. WILL LIKELY BE ENOUGH RESIDUAL BOUNDARY LAYER MOISTURE TO SUPPORT SOME AFTERNOON STRATOCU BUT EXPECT A FAIR AMOUNT OF INSOLATION TO ADD A DEGREE OR TWO TO THAT. GIVEN YESTERDAYS EXTREME WARM BIAS IN MOS GUIDANCE...WILL NUDGE THE FORECAST TOWARD COOLER RAW TEMPS. HESITANT TO DEVIATE LARGELY THOUGH. THIS IS AN ANOMALOUSLY COLD AIRMASS BUT THERMAL PROFILES WILL BE RECOVERING BY THE AFTERNOON AND DECREASING CLOUDS SHOULD ALLOW HIGHS TO CLIMB A BIT WARMER THAN YESTERDAY...GENERALLY LOW TO MID 40S. DIFFICULT MIN TEMP FORECAST TONIGHT. SURFACE ANTICYCLONE WILL BE OVERHEAD DURING THE EVENING HOURS BUT MODELS SUGGEST LIGHT SOUTHEAST WINDS DEVELOPING BY EARLY SUNDAY MORNING ALONG WITH PERHAPS SOME INCREASING MID/UPPER LEVEL CLOUDS. CURRENT TIMING INDICATES THESE CONDITIONS WILL BE TOO LATE TO PREVENT SUBSTANTIAL RADIATIVE LOSSES THOUGH AND HAVE THEREFORE PUSHED TEMPS DOWN A BIT. EXPECT GENERALLY MID TO UPPER 20S BUT A FEW ISOLATED LOWER 20S ARE POSSIBLE ACROSS THE NORTH. && .LONG TERM...(SUNDAY THROUGH FRIDAY) ISSUED AT 352 AM EDT SAT APR 20 2013 MODELS SUGGEST PERSISTENT PATTERN WITH A CONTINUATION OF A SERIES OF SHRTWVS DIGGING SE FROM WRN CANADA INTO THE PLAINS AND THEN LIFTING OUT TO THE NE ACROSS THE GRTLKS RESULTING IN PERIODIC BOUTS OF INCLEMENT WX WITH TEMPS GENERALLY AOB NORMAL. HIGH PRESSURE OVER THE NRN PLAINS THIS MORNING IS EXPECTED TO MOVE TO THE ERN GRTLKS AND NEW ENGLAND BY SUNDAY AND THEN SLOWLY EAST INTO THE WRN ATLANTIC MONDAY AS NEXT SHRTWV DIGGING INTO THE PLAINS AMPLIFIES THE FLOW ALOFT. THIS SHOULD RESULT IN FAIR WX WITH A WARMING TREND SUNDAY-MONDAY. ANOTHER STRENGTHENING LOW PRESSURE SYSTEM IS EXPECTED TO LIFT NE FROM THE SRN PLAINS MONDAY ACROSS THE WRN GRTLKS TUE-TUE NGT RESULTING IN A PERIOD OF SHOWERS AND PSBLY A FEW TSTMS IN THIS TIMEFRAME. GENERALLY DRY AND COOLER WX SHOULD FOLLOW IN THE WAKE OF THIS SYSTEM WED-THU... THOUGH DID MENTION A SLIGHT CHC OF SHOWERS DURING THE DAYS AS LONGWAVE TROF MOVES SLOWLY EAST ACROSS THE GRTLKS. DRY WX WITH WARMER TEMPS EXPECTED FRI AS SWLY FLOW DVLPS ACROSS OUR AREA ONCE AGAIN AHEAD OF NEXT SHRTWV/CDFNT MOVG INTO THE PLAINS. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON) ISSUED AT 210 PM EDT SAT APR 20 2013 DIURNAL VFR CU WILL DIMISH THIS EVENING LEAVING MOSTLY CLEAR SKIES IN PLACE FOR MUCH OF THE NIGHT. HIGH CLOUDINESS SHOULD INCREASE BY MORNING...LOWERING TO A MID LEVEL CIG SUNDAY MORNING. NORTHWEST WINDS AROUND 10 KNOTS WILL BECOME LIGHT AND VARIABLE AS SFC RIDGE AXIS OVERSPREADS THE SOUTHERN GREAT LAKES. SOUTHEAST WINDS 10 TO 15 KNOTS TO DEVELOP MID TO LATE MORNING SUNDAY AS THE SFC HIGH MOVES OFF TO THE EAST. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...NONE. MI...NONE. OH...NONE. LM...SMALL CRAFT ADVISORY UNTIL 5 PM EDT THIS AFTERNOON FOR LMZ043- 046. && $$ UPDATE...MARSILI SHORT TERM...AGD LONG TERM...JT AVIATION...MARSILI
AREA FORECAST DISCUSSION
NWS NORTHERN INDIANA
1215 PM EDT SAT APR 20 2013 .UPDATE... ISSUED AT 1206 PM EDT SAT APR 20 2013 FAIRLY STRONG NEGATIVE VORTICITY ADVECTION ALOFT IN ASSOCIATION WITH DEPARTING UPPER LEVEL TROUGH WILL AID LARGE SCALE SUBSIDENCE THIS AFTERNOON. LACK OF CU FORMATION NOTED FROM NORTHEAST ILLINOIS INTO FAR NORTHWEST INDIANA IN ASSOCIATION WITH THIS INCREASING SUBSIDENCE SHOULD EVENTUALLY BECOME THE RULE ACROSS THE LOCAL AREA LATE THIS AFTERNOON. LINGERING LAKE EFFECT CLOUDINESS WILL DIMINISH OVER THE NEXT FEW HOURS AS LOW LEVEL FLOW ACROSS SOUTHERN LAKE MICHIGAN BEGINS TO TRANSITION TO MAINLY A DIVERGENT/ONSHORE TYPE. CU APPEARS TO BE FAIRLY THICK AND OF GOOD COVERAGE ACROSS PORTIONS OF EASTERN HALF OF CWA...ALTHOUGH GRADUALLY EXPECTING THIS CU FIELD TO BECOME LESS VERTICALLY DEVELOPED AND THINNER THROUGH TIME. DESPITE MAINTENANCE OF LOW LEVEL THERMAL TROUGH...INCREASED INSOLTATION SHOULD SUPPORT HIGHS CLOSE TO THAT OF GOING FORECAST OR PERHAPS JUST SHORT OF THAT IN SOME INSTANCES. WITH GOING FORECAST IN GOOD SHAPE...ONLY MADE SOME MARGINAL TWEAKS TO SKY COVER TO ACCOUNT FOR CURRENT TRENDS...OTHERWISE PREVIOUS FORECAST KEPT INTACT. && .SHORT TERM...(TODAY AND TONIGHT) ISSUED AT 352 AM EDT SAT APR 20 2013 SCATTERED SNOW SHOWERS CONTINUE ACROSS THE CWA AT PRESS TIME...AIDED BY PERSISTENT MOIST CYCLONIC FLOW ASSOCIATED WITH PASSING MIDLEVEL TROUGH AXIS. HI-RES FORECAST SOUNDINGS ALSO SHOW BOUNDARY LAYER HAS REMAINED WELL MIXED THROUGH THE OVERNIGHT HOURS...FURTHER SUPPORTING CONVECTIVE SNOW SHOWERS. QUESTION WILL BE WHETHER OR NOT ACTIVITY CAN PERSIST BEYOND 12Z. A FEW PREVIOUS RAP MODEL RUNS SUGGESTED ISOLATED RAIN/SNOW SHOWERS PERSISTING FOR MUCH OF THE MORNING AS ONE LAST RIBBON OF SHEAR VORTICITY ROTATES THROUGH THE AREA. HOWEVER...MIDLEVEL HEIGHTS WILL BE CLIMBING QUICKLY BY LATER THIS MORNING AND NAM BUFR DATA SHOWS LOWER TROPOSPHERIC DRY AIR INCREASING AS WELL AS A STRENGTHENING SUBSIDENCE INVERSION. THEREFORE EXPECT LITTLE MORE THAN ISOLATED FLURRIES AFTER 12Z WITH INCREASINGLY ANTICYCLONIC FLOW BRINGING DRY CONDITIONS EVERYWHERE BY MIDDAY. THERMAL TROUGH WILL BE SHIFTING EAST BY THE AFTERNOON BUT 850MB TEMPS STILL EXPECTED TO BE AROUND -8C DURING PEAK HEATING. MIXING THIS TO THE SURFACE ONLY GIVES HIGHS IN THE LOW 40S. WILL LIKELY BE ENOUGH RESIDUAL BOUNDARY LAYER MOISTURE TO SUPPORT SOME AFTERNOON STRATOCU BUT EXPECT A FAIR AMOUNT OF INSOLATION TO ADD A DEGREE OR TWO TO THAT. GIVEN YESTERDAYS EXTREME WARM BIAS IN MOS GUIDANCE...WILL NUDGE THE FORECAST TOWARD COOLER RAW TEMPS. HESITANT TO DEVIATE LARGELY THOUGH. THIS IS AN ANOMALOUSLY COLD AIRMASS BUT THERMAL PROFILES WILL BE RECOVERING BY THE AFTERNOON AND DECREASING CLOUDS SHOULD ALLOW HIGHS TO CLIMB A BIT WARMER THAN YESTERDAY...GENERALLY LOW TO MID 40S. DIFFICULT MIN TEMP FORECAST TONIGHT. SURFACE ANTICYCLONE WILL BE OVERHEAD DURING THE EVENING HOURS BUT MODELS SUGGEST LIGHT SOUTHEAST WINDS DEVELOPING BY EARLY SUNDAY MORNING ALONG WITH PERHAPS SOME INCREASING MID/UPPER LEVEL CLOUDS. CURRENT TIMING INDICATES THESE CONDITIONS WILL BE TOO LATE TO PREVENT SUBSTANTIAL RADIATIVE LOSSES THOUGH AND HAVE THEREFORE PUSHED TEMPS DOWN A BIT. EXPECT GENERALLY MID TO UPPER 20S BUT A FEW ISOLATED LOWER 20S ARE POSSIBLE ACROSS THE NORTH. && .LONG TERM...(SUNDAY THROUGH FRIDAY) ISSUED AT 352 AM EDT SAT APR 20 2013 MODELS SUGGEST PERSISTENT PATTERN WITH A CONTINUATION OF A SERIES OF SHRTWVS DIGGING SE FROM WRN CANADA INTO THE PLAINS AND THEN LIFTING OUT TO THE NE ACROSS THE GRTLKS RESULTING IN PERIODIC BOUTS OF INCLEMENT WX WITH TEMPS GENERALLY AOB NORMAL. HIGH PRESSURE OVER THE NRN PLAINS THIS MORNING IS EXPECTED TO MOVE TO THE ERN GRTLKS AND NEW ENGLAND BY SUNDAY AND THEN SLOWLY EAST INTO THE WRN ATLANTIC MONDAY AS NEXT SHRTWV DIGGING INTO THE PLAINS AMPLIFIES THE FLOW ALOFT. THIS SHOULD RESULT IN FAIR WX WITH A WARMING TREND SUNDAY-MONDAY. ANOTHER STRENGTHENING LOW PRESSURE SYSTEM IS EXPECTED TO LIFT NE FROM THE SRN PLAINS MONDAY ACROSS THE WRN GRTLKS TUE-TUE NGT RESULTING IN A PERIOD OF SHOWERS AND PSBLY A FEW TSTMS IN THIS TIMEFRAME. GENERALLY DRY AND COOLER WX SHOULD FOLLOW IN THE WAKE OF THIS SYSTEM WED-THU... THOUGH DID MENTION A SLIGHT CHC OF SHOWERS DURING THE DAYS AS LONGWAVE TROF MOVES SLOWLY EAST ACROSS THE GRTLKS. DRY WX WITH WARMER TEMPS EXPECTED FRI AS SWLY FLOW DVLPS ACROSS OUR AREA ONCE AGAIN AHEAD OF NEXT SHRTWV/CDFNT MOVG INTO THE PLAINS. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SUNDAY MORNING) ISSUED AT 557 AM EDT SAT APR 20 2013 SNOW SHOWERS ARE GRADUALLY TAPERING OFF AS MIDLEVEL TROUGH AXIS LIFTS NORTHEAST AND SUBSIDENCE BUILDS ACROSS THE REGION. A FEW BRIEF PERIODS OF MVFR CONDITIONS REMAIN POSSIBLE OVER THE NEXT FEW HOURS THOUGH. STRATOCU WILL GRADUALLY CLEAR OUT OVER THE COURSE OF THE DAY AS DRIER AIR ADVECTS INTO THE REGION. DEEP MIXING HEIGHTS WILL KEEP CEILINGS WELL INTO VFR CATEGORY REGARDLESS. WEAKENING GRADIENT WILL ALSO BRING DECREASING WINDS THROUGH THE TAF PERIOD. && .IWX WATCHES/WARNINGS/ADVISORIES... IN...NONE. MI...NONE. OH...NONE. LM...SMALL CRAFT ADVISORY UNTIL 5 PM EDT THIS AFTERNOON FOR LMZ043- 046. && $$ UPDATE...MARSILI SHORT TERM...AGD LONG TERM...JT AVIATION...AGD
AREA FORECAST DISCUSSION
NWS GAYLORD MI
120 PM EDT SAT APR 20 2013 .SYNOPSIS... ISSUED AT 1058 AM EDT SAT APR 20 2013 LAKE EFFECT SNOW SHOWERS WILL CONTINUE TO IMPACT NORTHERN MICHIGAN THROUGH THE EARLY AFTERNOON HOURS...TARGETING THE TYPICAL SNOWBELT REGIONS OF EASTERN UPPER AND NORTHWEST LOWER MICHIGAN FOR THE MOST PERSISTENT AND HEAVIEST SNOW SHOWERS. HIGH PRESSURE WILL BEGIN TO SETTLE INTO THE GREAT LAKES REGION THIS AFTERNOON...BRINGING QUIET AND SEASONABLY CHILLY WEATHER TO NORTHERN MICHIGAN THROUGH THE REST OF THE WEEKEND. THE NEXT CHANCE OF RAIN ARRIVES FOR THE BEGINNING OF THE WORK WEEK AS SEVERAL WAVES OF LOW PRESSURE PUSH ACROSS THE REGION. && .UPDATE... ISSUED AT 1246 PM EDT SAT APR 20 2013 DIURNAL "HEATING" PROCESSES DOING ITS PART IN CREATING A MORE CELLULAR LOOK TO THE SNOW ON LATEST RADAR. THE PREVIOUS DOMINANT BAND IS STILL VISIBLE...WITH IT`S EXTENSION REACHING BACK TOWARD BEAVER ISLAND...BUT ALL OF THE BETTER SNOWS HAVE INDEED DWINDLED AND BECOME BRIEF. MOST OF THE TIME...FLURRIES CAN BE EXPECTED. NO SIGNIFICANT CHANGES THIS UPDATE. DID EXTEND SEEING FLURRIES FOR AN HOUR OR SO INTO THIS AFTERNOON...EVEN FURTHER INLAND AWAY FROM THE LAKES. UPDATE ISSUED AT 1052 AM EDT SAT APR 20 2013 DOMINANT BAND OF MODERATE SNOWFALL CONTINUES TO DRIFT NE INTO OTSEGO...CHARLEVOIX AND NRN CRAWFORD COUNTIES. ALTHOUGH THE SNOWFALL IS RATHER IMPRESSIVE...ESPECIALLY FOR MID-LATE APRIL...THE TIME OF YEAR/SUN ANGLE IS NOT ALLOWING SNOW TO ACCUMULATE MUCH ANYMORE. WE DID HAVE REPORTS OF 1-2 INCHES OF SNOW OVERNIGHT...AND THESE AMOUNTS WILL NOT BE MET TODAY. THIS IS ALSO SUPPORTED BY AN EXPECTED TRANSITION TO MORE CELLULAR SHOWERS WITH INCREASED LOW LEVEL LAPSE RATES...A LOSS OF CYCLONIC CONVERGENCE AND DRY AIR ENTRAINMENT FROM INVADING HIGH PRESSURE UPSTREAM. WILL HAVE SOME PEEKS OF SUN AT TIMES...BUT SKIES ARE EXPECTED TO CLEAR MORE SO LATER THIS AFTERNOON...AS THE BETTER DRY AIR UPSTREAM FILLS IN BEHIND FINAL SFC TROUGH FROM NRN WISCONSIN THROUGH EASTERN LAKE SUPERIOR. WILL ALLOW WINTER HEADLINES TO EXPIRE...WITH IMPACTS FROM CONTINUED SNOW TO BE MINIMAL. ROADS WILL JUST BE WET FOR MOST ALL AREAS WITHIN THE ADVISORY. UPDATE ISSUED AT 717 AM EDT SAT APR 20 2013 MULTI-BAND LAKE EFFECT SNOW SHOWERS HAVE FULLY DEVELOPED ACROSS OUR CWA...WITH THE DOMINANT BAND EXTENDING FROM NEAR ALDEN TO KALKASKA. HEAVIER SNOW SHOWERS REMAIN EMBEDDED WITHIN THIS DOMINANT BAND...WITH SNOWFALL RATES OF AROUND AN INCH AN HOUR. WILL MAINTAIN THE LAKE SNOW ADVISORY FOR THE SNOWBELT REGION OF NW AND N CENTRAL LWR MICHIGAN THRU LATE MORNING...AT WHICH TIME SNOW SHOWERS SHOULD BEGIN TO BREAK DOWN AS HIGH PRESSURE AND DRIER AIR BEGIN TO BUILD INTO THE WRN GREAT LAKES. && .SHORT TERM...(TODAY THROUGH TONIGHT) ISSUED AT 300 AM EDT SAT APR 20 2013 WELL...THIS JUST ISN`T RIGHT FOR MID APRIL...COLD AND GUSTY NORTHWEST WINDS...WITH NUMEROUS GROUND WHITENING LAKE INDUCED SNOW SHOWERS TARGETING THE TRADITIONAL SNOW BELTS. CULPRIT BEHIND THIS NONSENSE IS ANOMALOUSLY DEEP TROUGH EXTENDING FROM THE MID MISSISSIPPI VALLEY UP THROUGH JAMES BAY. ATTENDANT BEHEMOTH SURFACE LOW NOW WELL TO OUR NORTHEAST UP ACROSS CENTRAL QUEBEC...WITH SURFACE TROUGH AXIS EXTENDING BACK SOUTHWEST INTO OUR AREA. COMBO OF DEEP MOISTURE AND MORE THAN PLENTIFUL OVER-WATER INSTABILITY (H8 TEMPERATURES DOWN AROUND -14/-15C PER RAP ANALYSIS) HELPING DRIVE THOSE LAKE SNOWS. FORECAST CONCERNS THROUGH THE SHORT TERM REAL CENTERED WITHIN THE FIRST HALF OF TODAY...CENTERING ON LINGERING LAKE INDUCED SNOW POTENTIAL AND POSSIBLE ADDITIONAL ACCUMULATIONS. RESPECTABLE LAKE SNOW PARAMETERS REMAIN IN PLACE EARLY ON THIS MORNING...WITH MORE THAN SUFFICIENT DELTA T/S AUGMENTED BY REMNANT DEEPER MOISTURE AND GOOD INVERSION LEVELS UP THROUGH H7 LEVELS. NNW (LAKE SUPERIOR) TO NW (NORTHERN LAKE MICHIGAN) FLOW REGIME WILL LOCKED IN BY SUNRISE...TARGETING THE NORTHWEST LOWER SNOWBELTS FOR THE MOST PERSISTENT AND HEAVIEST ACTIVITY. GIVEN FLOW...WOULD EXPECT BETTER LAKE SUPERIOR ACTIVITY TO REMAIN JUST WEST OF CHIPPEWA COUNTY. DECISIVE DOWNTURN IN LAKE SNOW PARAMETERS EXPECTED AFTER ABOUT 15Z...WITH STEADY LOSS OF SYNOPTIC MOISTURE SUPPORT AND LOWERING INVERSION LEVELS. DIURNAL DISRUPTION WILL ONLY HELP THE CAUSE..AS WILL DEEPENING OF SURFACE BASED DRY WEDGE. WOULD EXPECT SCATTERED LATE MORNING ACTIVITY TO COMPLETELY END BY EARLY AFTERNOON (YUP...SAID THAT BEFORE). UPSHOT TO ALL THE ABOVE...THINKING PERHAPS ANOTHER INCH OR SO IN NORTHWEST LOWER SNOWBELTS THIS MORNING...LEAVING THE INHERITED LAKE SNOW ADVISORY THROUGH ITS DURATION ENDING AT 15Z. LESS ACCUMULATION EXPECTED ELSEWHERE. DRYING REMAINS AGGRESSIVE THROUGH THE AFTERNOON...AND STILL EXPECT SKIES TO TREND PARTLY SUNNY TO SUNNY ALL AREAS. UNFORTUNATELY...EVEN MID APRIL SUN WILL DO LITTLE TO HELP THE TEMPERATURE CAUSE...WITH READINGS A SOLID 15 TO 20 DEGREES BELOW NORMAL. GUSTY NORTHWEST WINDS WILL SUBSIDE THROUGH THE DAY...BUT NOT BEFORE MAKING IT FEEL DOWNRIGHT COLD THROUGH THE EARLY AFTERNOON. MUCH QUIETER HEADING INTO TONIGHT AS DRYING BECOMES COMPLETE AND HIGH PRESSURE BUILDS DIRECTLY OVERHEAD. MOSTLY CLEAR SKIES...WITH PERHAPS A TOUCH OF HIGH CLOUDS LATE. RADIATION COOLING TRIFECTA... WITH QUICK LOSS OF WINDS...CLEAR SKIES..AND DRY LOW LEVELS. GUIDANCE CONTINUES TO TREND COLDER...NOW SHOWING THE TRADITIONAL ICE BOX LOCALES FLIRTING WITH THE UPPER SINGLE DIGITS. WILL NOT GO QUITE THIS AGGRESSIVE...USING LOWER TEENS FOR THE COLDER LOCATIONS. THESE NUMBERS FLIRT WITH RECORD LOWS FOR THE DAY...WITHIN A FEW DEGREES AT SEVERAL SITES. COULD EASILY SEE A RECORD TO TWO BROKEN BY SUNRISE SUNDAY. .LONG TERM...(SUNDAY THROUGH FRIDAY) ISSUED AT 300 AM EDT SAT APR 20 2013 .SUNDAY AND MONDAY...STRONG SURFACE HIGH PRESSURE CENTER SHIFTS EAST OF MICHIGAN BY 12Z SUNDAY. AFTER A FRIGID START TO THE DAY...WITH EARLY MORNING LOWS IN THE TEENS (WHICH IS ROUGHLY 20 DEGREES BELOW NORMAL)...TEMPS WILL REBOUND NICELY AS SOUTHERLY FLOW KICKS IN ON THE BACK SIDE OF THE HIGH CENTER. CLOUDS WILL INCREASE/THICKEN/LOWER FROM WEST TO EAST AS MAINLY MID/UPPER LEVEL MOISTURE BEGINS TO ADVECT INTO THE WRN GREAT LAKES IN ADVANCE OF A COLD FRONT DRIVING EAST THRU MINNESOTA. STILL APPEARS ANY PRECIP CHANCES WILL HOLD OFF UNTIL SUNDAY NIGHT...AND WILL BE CONFINED TO MAINLY ERN UPR MICHIGAN. ONCE THE COLD FRONT REACHES WRN UPR MICHIGAN AND WISCONSIN...UPPER LEVEL FLOW BECOMES NEARLY PARALLEL WITH THE FRONT ITSELF...WHICH WILL SLOW ITS EASTWARD PROGRESS. ALSO...A WAVE DEVELOPS ALONG THE FRONT...DEEPENING INTO A CLOSED LOW THAT DRIVES NE THRU THE STRAITS ON TUESDAY (MORE ON THIS BELOW). WITH THE SLOW EASTWARD PUSH OF THE FRONT AND ASSOCIATED MOISTURE...POPS WILL GRADUALLY SPREAD FROM ERN UPR MICHIGAN SUNDAY NIGHT INTO THE STRAITS AND ALONG THE LAKE MICHIGAN SHORELINE TO LEELANAU COUNTY ON MONDAY...AND THEN FINALLY MAKE SOME HEADWAY INTO NRN LWR MICHIGAN WEST OF A LINE FROM ROGERS CITY TO HTL LATE MONDAY NIGHT AS THAT WAVE (MENTIONED ABOVE) BEGINS TO LIFT INTO OUR CWA. AGAIN...TEMPS WILL RECOVER NICELY DURING THE FIRST PART OF NEXT WEEK THANKS TO WAA AHEAD OF THE SLOW COLD FRONT. HIGHS ON SUNDAY WILL WARM INTO THE MID 40S TO LOWER 50S...BUT WILL COOL BACK INTO THE 30S AT NIGHT. HOWEVER...PRECIP SUNDAY NIGHT IN ERN UPR MICHIGAN SHOULD BE ALL LIQUID PER NAM BUFR SOUNDINGS SHOWING A SURFACE-BASED ABOVE FREEZING LAYER THRU 850 MB. WAA FURTHER STRENGTHENS ON MONDAY...WITH TEMPS CLIMBING TO NEAR 50 IN ERN UPR MICHIGAN AND WELL INTO THE 50S TO NEAR 60 ACROSS NRN LWR MICHIGAN. COLD FRONT REMAINS WEST OF OUR CWA MONDAY NIGHT. TEMPS WILL COOLING MAINLY BACK INTO THE 40S MONDAY NIGHT...KEEPING ANY PRECIP ALL LIQUID. TUESDAY THRU FRIDAY...AS MENTIONED ABOVE...FIRST WAVE TRACKS ALONG THE COLD FRONT AND THRU THE STRAITS TUESDAY MORNING. THIS FEATURE COMBINED WITH DEEP MOISTURE WILL PRODUCE RAIN SHOWERS ACROSS MUCH OF OUR CWA ON TUESDAY. SECOND WAVE DEVELOPS ALONG THE FRONT AND TRACKS THRU SRN LWR MICHIGAN TUESDAY NIGHT...SPREADING ANOTHER AREA OF RAIN SHOWERS THRU MOST OF MICHIGAN. WITH AREA RIVERS ALREADY RUNNING HIGH FROM RECENT RAIN AND SNOWMELT...WILL NEED TO KEEP AN EYE ON THE POTENTIAL FOR HEAVY RAINFALL ESPECIALLY WITH THIS SECOND WAVE AS IT BEGINS TO TAP INTO GULF MOISTURE TUESDAY NIGHT. FOR NOW...WILL STICK WITH LIKELY POPS FOR TUESDAY AND TUESDAY NIGHT ACROSS MOST OF OUR CWA. PRECIP CHANCES DIMINISH ON WEDNESDAY AS THE FRONT EXITS TO THE EAST COAST AND SURFACE RIDGING BUILDS INTO MICHIGAN. A WEAK MOISTURE-STARVED NRN STREAM WAVE QUICKLY SWINGS THRU MICHIGAN THURSDAY...PRODUCING A QUICK CHANCE OF LIGHT RAIN. DEEPER MOISTURE WILL BEGIN TO ADVECT INTO THE WRN GREAT LAKES ON FRIDAY ONCE SOUTHERLY RETURN FLOW KICKS IN ON THE BACK SIDE OF HIGH PRESSURE. FIRST LOOK AT NEXT WEEKEND LOOKS UNSETTLED WITH NEAR NORMAL TEMPS IN THE 50S. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON) ISSUED AT 1246 PM EDT SAT APR 20 2013 ANY LINGERING LAKE EFFECT SNOW SHOWERS WILL END WITHIN THE FIRST FEW HOURS OF THE TAF PERIOD...AS HIGH PRESSURE BUILDS BEHIND THE DEPARTING STORM SYSTEM OVER QUEBEC. VFR CONDITIONS WILL PREVAIL THROUGHOUT THE ENTIRE TAF PERIOD FOR ALL TAF SITES. SKIES WILL CLEAR OUT THIS EVENING UNTIL A DECK OF MID-LEVEL CLOUDS OVERTAKE NORTHERN MICHIGAN TOMORROW MORNING. && .MARINE... ISSUED AT 120 PM EDT SAT APR 20 2013 WINDS KEEP GUSTING INTO ADVISORY LEVELS..GALES ACROSS PRESQUE ISLE DUE TO TIGHT GRADIENT AND VERY UNSTABLE CONDITIONS OVER THE GREAT LAKES. RAPIDLY APPROACHING HIGH PRESSURE WILL ALLOW THESE HEADLINES TO END BY EVENING. NO WORRIES THROUGH MUCH OF TOMORROW SUNDAY...HOWEVER NEXT FRONT APPROACHES AND TIGHTENS UP THE GRADIENT AGAIN. SOUTHERLY WINDS WILL BE BLOWING TO ADVISORY LEVEL ACROSS MAINLY THE LAKE MICHIGAN NEARSHORE WATERS LATE SUNDAY THROUGH MONDAY. TIMING OF THIS FRONT IS UNCERTAIN...BUT CHANCES FOR RAIN ARRIVE PRIMARILY TUESDAY. && .APX WATCHES/WARNINGS/ADVISORIES... MI...NONE. LH...SMALL CRAFT ADVISORY UNTIL 5 PM EDT THIS AFTERNOON FOR LHZ345- 346-349. GALE WARNING UNTIL 5 PM EDT THIS AFTERNOON FOR LHZ347-348. LM...SMALL CRAFT ADVISORY UNTIL 5 PM EDT THIS AFTERNOON FOR LMZ323- 341-342-344>346. LS...SMALL CRAFT ADVISORY UNTIL 5 PM EDT THIS AFTERNOON FOR LSZ321- 322. && $$ UPDATE...SD SYNOPSIS...MR SHORT TERM...MB LONG TERM...MR AVIATION...TL MARINE...SD
AREA FORECAST DISCUSSION
NWS GAYLORD MI
1252 PM EDT SAT APR 20 2013 .SYNOPSIS... ISSUED AT 1058 AM EDT SAT APR 20 2013 LAKE EFFECT SNOW SHOWERS WILL CONTINUE TO IMPACT NORTHERN MICHIGAN THROUGH THE EARLY AFTERNOON HOURS...TARGETING THE TYPICAL SNOWBELT REGIONS OF EASTERN UPPER AND NORTHWEST LOWER MICHIGAN FOR THE MOST PERSISTENT AND HEAVIEST SNOW SHOWERS. HIGH PRESSURE WILL BEGIN TO SETTLE INTO THE GREAT LAKES REGION THIS AFTERNOON...BRINGING QUIET AND SEASONABLY CHILLY WEATHER TO NORTHERN MICHIGAN THROUGH THE REST OF THE WEEKEND. THE NEXT CHANCE OF RAIN ARRIVES FOR THE BEGINNING OF THE WORK WEEK AS SEVERAL WAVES OF LOW PRESSURE PUSH ACROSS THE REGION. && .UPDATE... ISSUED AT 1246 PM EDT SAT APR 20 2013 DIURNAL "HEATING" PROCESSES DOING ITS PART IN CREATING A MORE CELLULAR LOOK TO THE SNOW ON LATEST RADAR. THE PREVIOUS DOMINANT BAND IS STILL VISIBLE...WITH IT`S EXTENSION REACHING BACK TOWARD BEAVER ISLAND...BUT ALL OF THE BETTER SNOWS HAVE INDEED DWINDLED AND BECOME BRIEF. MOST OF THE TIME...FLURRIES CAN BE EXPECTED. NO SIGNIFICANT CHANGES THIS UPDATE. DID EXTEND SEEING FLURRIES FOR AN HOUR OR SO INTO THIS AFTERNOON...EVEN FURTHER INLAND AWAY FROM THE LAKES. UPDATE ISSUED AT 1052 AM EDT SAT APR 20 2013 DOMINANT BAND OF MODERATE SNOWFALL CONTINUES TO DRIFT NE INTO OTSEGO...CHARLEVOIX AND NRN CRAWFORD COUNTIES. ALTHOUGH THE SNOWFALL IS RATHER IMPRESSIVE...ESPECIALLY FOR MID-LATE APRIL...THE TIME OF YEAR/SUN ANGLE IS NOT ALLOWING SNOW TO ACCUMULATE MUCH ANYMORE. WE DID HAVE REPORTS OF 1-2 INCHES OF SNOW OVERNIGHT...AND THESE AMOUNTS WILL NOT BE MET TODAY. THIS IS ALSO SUPPORTED BY AN EXPECTED TRANSITION TO MORE CELLULAR SHOWERS WITH INCREASED LOW LEVEL LAPSE RATES...A LOSS OF CYCLONIC CONVERGENCE AND DRY AIR ENTRAINMENT FROM INVADING HIGH PRESSURE UPSTREAM. WILL HAVE SOME PEEKS OF SUN AT TIMES...BUT SKIES ARE EXPECTED TO CLEAR MORE SO LATER THIS AFTERNOON...AS THE BETTER DRY AIR UPSTREAM FILLS IN BEHIND FINAL SFC TROUGH FROM NRN WISCONSIN THROUGH EASTERN LAKE SUPERIOR. WILL ALLOW WINTER HEADLINES TO EXPIRE...WITH IMPACTS FROM CONTINUED SNOW TO BE MINIMAL. ROADS WILL JUST BE WET FOR MOST ALL AREAS WITHIN THE ADVISORY. UPDATE ISSUED AT 717 AM EDT SAT APR 20 2013 MULTI-BAND LAKE EFFECT SNOW SHOWERS HAVE FULLY DEVELOPED ACROSS OUR CWA...WITH THE DOMINANT BAND EXTENDING FROM NEAR ALDEN TO KALKASKA. HEAVIER SNOW SHOWERS REMAIN EMBEDDED WITHIN THIS DOMINANT BAND...WITH SNOWFALL RATES OF AROUND AN INCH AN HOUR. WILL MAINTAIN THE LAKE SNOW ADVISORY FOR THE SNOWBELT REGION OF NW AND N CENTRAL LWR MICHIGAN THRU LATE MORNING...AT WHICH TIME SNOW SHOWERS SHOULD BEGIN TO BREAK DOWN AS HIGH PRESSURE AND DRIER AIR BEGIN TO BUILD INTO THE WRN GREAT LAKES. && .SHORT TERM...(TODAY THROUGH TONIGHT) ISSUED AT 300 AM EDT SAT APR 20 2013 WELL...THIS JUST ISN`T RIGHT FOR MID APRIL...COLD AND GUSTY NORTHWEST WINDS...WITH NUMEROUS GROUND WHITENING LAKE INDUCED SNOW SHOWERS TARGETING THE TRADITIONAL SNOW BELTS. CULPRIT BEHIND THIS NONSENSE IS ANOMALOUSLY DEEP TROUGH EXTENDING FROM THE MID MISSISSIPPI VALLEY UP THROUGH JAMES BAY. ATTENDANT BEHEMOTH SURFACE LOW NOW WELL TO OUR NORTHEAST UP ACROSS CENTRAL QUEBEC...WITH SURFACE TROUGH AXIS EXTENDING BACK SOUTHWEST INTO OUR AREA. COMBO OF DEEP MOISTURE AND MORE THAN PLENTIFUL OVER-WATER INSTABILITY (H8 TEMPERATURES DOWN AROUND -14/-15C PER RAP ANALYSIS) HELPING DRIVE THOSE LAKE SNOWS. FORECAST CONCERNS THROUGH THE SHORT TERM REAL CENTERED WITHIN THE FIRST HALF OF TODAY...CENTERING ON LINGERING LAKE INDUCED SNOW POTENTIAL AND POSSIBLE ADDITIONAL ACCUMULATIONS. RESPECTABLE LAKE SNOW PARAMETERS REMAIN IN PLACE EARLY ON THIS MORNING...WITH MORE THAN SUFFICIENT DELTA T/S AUGMENTED BY REMNANT DEEPER MOISTURE AND GOOD INVERSION LEVELS UP THROUGH H7 LEVELS. NNW (LAKE SUPERIOR) TO NW (NORTHERN LAKE MICHIGAN) FLOW REGIME WILL LOCKED IN BY SUNRISE...TARGETING THE NORTHWEST LOWER SNOWBELTS FOR THE MOST PERSISTENT AND HEAVIEST ACTIVITY. GIVEN FLOW...WOULD EXPECT BETTER LAKE SUPERIOR ACTIVITY TO REMAIN JUST WEST OF CHIPPEWA COUNTY. DECISIVE DOWNTURN IN LAKE SNOW PARAMETERS EXPECTED AFTER ABOUT 15Z...WITH STEADY LOSS OF SYNOPTIC MOISTURE SUPPORT AND LOWERING INVERSION LEVELS. DIURNAL DISRUPTION WILL ONLY HELP THE CAUSE..AS WILL DEEPENING OF SURFACE BASED DRY WEDGE. WOULD EXPECT SCATTERED LATE MORNING ACTIVITY TO COMPLETELY END BY EARLY AFTERNOON (YUP...SAID THAT BEFORE). UPSHOT TO ALL THE ABOVE...THINKING PERHAPS ANOTHER INCH OR SO IN NORTHWEST LOWER SNOWBELTS THIS MORNING...LEAVING THE INHERITED LAKE SNOW ADVISORY THROUGH ITS DURATION ENDING AT 15Z. LESS ACCUMULATION EXPECTED ELSEWHERE. DRYING REMAINS AGGRESSIVE THROUGH THE AFTERNOON...AND STILL EXPECT SKIES TO TREND PARTLY SUNNY TO SUNNY ALL AREAS. UNFORTUNATELY...EVEN MID APRIL SUN WILL DO LITTLE TO HELP THE TEMPERATURE CAUSE...WITH READINGS A SOLID 15 TO 20 DEGREES BELOW NORMAL. GUSTY NORTHWEST WINDS WILL SUBSIDE THROUGH THE DAY...BUT NOT BEFORE MAKING IT FEEL DOWNRIGHT COLD THROUGH THE EARLY AFTERNOON. MUCH QUIETER HEADING INTO TONIGHT AS DRYING BECOMES COMPLETE AND HIGH PRESSURE BUILDS DIRECTLY OVERHEAD. MOSTLY CLEAR SKIES...WITH PERHAPS A TOUCH OF HIGH CLOUDS LATE. RADIATION COOLING TRIFECTA... WITH QUICK LOSS OF WINDS...CLEAR SKIES..AND DRY LOW LEVELS. GUIDANCE CONTINUES TO TREND COLDER...NOW SHOWING THE TRADITIONAL ICE BOX LOCALES FLIRTING WITH THE UPPER SINGLE DIGITS. WILL NOT GO QUITE THIS AGGRESSIVE...USING LOWER TEENS FOR THE COLDER LOCATIONS. THESE NUMBERS FLIRT WITH RECORD LOWS FOR THE DAY...WITHIN A FEW DEGREES AT SEVERAL SITES. COULD EASILY SEE A RECORD TO TWO BROKEN BY SUNRISE SUNDAY. .LONG TERM...(SUNDAY THROUGH FRIDAY) ISSUED AT 300 AM EDT SAT APR 20 2013 .SUNDAY AND MONDAY...STRONG SURFACE HIGH PRESSURE CENTER SHIFTS EAST OF MICHIGAN BY 12Z SUNDAY. AFTER A FRIGID START TO THE DAY...WITH EARLY MORNING LOWS IN THE TEENS (WHICH IS ROUGHLY 20 DEGREES BELOW NORMAL)...TEMPS WILL REBOUND NICELY AS SOUTHERLY FLOW KICKS IN ON THE BACK SIDE OF THE HIGH CENTER. CLOUDS WILL INCREASE/THICKEN/LOWER FROM WEST TO EAST AS MAINLY MID/UPPER LEVEL MOISTURE BEGINS TO ADVECT INTO THE WRN GREAT LAKES IN ADVANCE OF A COLD FRONT DRIVING EAST THRU MINNESOTA. STILL APPEARS ANY PRECIP CHANCES WILL HOLD OFF UNTIL SUNDAY NIGHT...AND WILL BE CONFINED TO MAINLY ERN UPR MICHIGAN. ONCE THE COLD FRONT REACHES WRN UPR MICHIGAN AND WISCONSIN...UPPER LEVEL FLOW BECOMES NEARLY PARALLEL WITH THE FRONT ITSELF...WHICH WILL SLOW ITS EASTWARD PROGRESS. ALSO...A WAVE DEVELOPS ALONG THE FRONT...DEEPENING INTO A CLOSED LOW THAT DRIVES NE THRU THE STRAITS ON TUESDAY (MORE ON THIS BELOW). WITH THE SLOW EASTWARD PUSH OF THE FRONT AND ASSOCIATED MOISTURE...POPS WILL GRADUALLY SPREAD FROM ERN UPR MICHIGAN SUNDAY NIGHT INTO THE STRAITS AND ALONG THE LAKE MICHIGAN SHORELINE TO LEELANAU COUNTY ON MONDAY...AND THEN FINALLY MAKE SOME HEADWAY INTO NRN LWR MICHIGAN WEST OF A LINE FROM ROGERS CITY TO HTL LATE MONDAY NIGHT AS THAT WAVE (MENTIONED ABOVE) BEGINS TO LIFT INTO OUR CWA. AGAIN...TEMPS WILL RECOVER NICELY DURING THE FIRST PART OF NEXT WEEK THANKS TO WAA AHEAD OF THE SLOW COLD FRONT. HIGHS ON SUNDAY WILL WARM INTO THE MID 40S TO LOWER 50S...BUT WILL COOL BACK INTO THE 30S AT NIGHT. HOWEVER...PRECIP SUNDAY NIGHT IN ERN UPR MICHIGAN SHOULD BE ALL LIQUID PER NAM BUFR SOUNDINGS SHOWING A SURFACE-BASED ABOVE FREEZING LAYER THRU 850 MB. WAA FURTHER STRENGTHENS ON MONDAY...WITH TEMPS CLIMBING TO NEAR 50 IN ERN UPR MICHIGAN AND WELL INTO THE 50S TO NEAR 60 ACROSS NRN LWR MICHIGAN. COLD FRONT REMAINS WEST OF OUR CWA MONDAY NIGHT. TEMPS WILL COOLING MAINLY BACK INTO THE 40S MONDAY NIGHT...KEEPING ANY PRECIP ALL LIQUID. TUESDAY THRU FRIDAY...AS MENTIONED ABOVE...FIRST WAVE TRACKS ALONG THE COLD FRONT AND THRU THE STRAITS TUESDAY MORNING. THIS FEATURE COMBINED WITH DEEP MOISTURE WILL PRODUCE RAIN SHOWERS ACROSS MUCH OF OUR CWA ON TUESDAY. SECOND WAVE DEVELOPS ALONG THE FRONT AND TRACKS THRU SRN LWR MICHIGAN TUESDAY NIGHT...SPREADING ANOTHER AREA OF RAIN SHOWERS THRU MOST OF MICHIGAN. WITH AREA RIVERS ALREADY RUNNING HIGH FROM RECENT RAIN AND SNOWMELT...WILL NEED TO KEEP AN EYE ON THE POTENTIAL FOR HEAVY RAINFALL ESPECIALLY WITH THIS SECOND WAVE AS IT BEGINS TO TAP INTO GULF MOISTURE TUESDAY NIGHT. FOR NOW...WILL STICK WITH LIKELY POPS FOR TUESDAY AND TUESDAY NIGHT ACROSS MOST OF OUR CWA. PRECIP CHANCES DIMINISH ON WEDNESDAY AS THE FRONT EXITS TO THE EAST COAST AND SURFACE RIDGING BUILDS INTO MICHIGAN. A WEAK MOISTURE-STARVED NRN STREAM WAVE QUICKLY SWINGS THRU MICHIGAN THURSDAY...PRODUCING A QUICK CHANCE OF LIGHT RAIN. DEEPER MOISTURE WILL BEGIN TO ADVECT INTO THE WRN GREAT LAKES ON FRIDAY ONCE SOUTHERLY RETURN FLOW KICKS IN ON THE BACK SIDE OF HIGH PRESSURE. FIRST LOOK AT NEXT WEEKEND LOOKS UNSETTLED WITH NEAR NORMAL TEMPS IN THE 50S. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON) ISSUED AT 1246 PM EDT SAT APR 20 2013 ANY LINGERING LAKE EFFECT SNOW SHOWERS WILL END WITHIN THE FIRST FEW HOURS OF THE TAF PERIOD...AS HIGH PRESSURE BUILDS BEHIND THE DEPARTING STORM SYSTEM OVER QUEBEC. VFR CONDITIONS WILL PREVAIL THROUGHOUT THE ENTIRE TAF PERIOD FOR ALL TAF SITES. SKIES WILL CLEAR OUT THIS EVENING UNTIL A DECK OF MID-LEVEL CLOUDS OVERTAKE NORTHERN MICHIGAN TOMORROW MORNING. && .MARINE... ISSUED AT 1052 AM EDT SAT APR 20 2013 UPDATE...GALES CONTINUE ACROSS PRESQUE ISLE...AND WILL EXTEND THE GALE WARNING THROUGH 1-2 PM. ALL OTHER AREAS WILL BE IN THE SMALL CRAFT ADVISORY FOR THE DAY. HEADLINES ARE EXPECTED TO BE LIFTED MOST ALL AREAS BY EVENING (MAYBE NOT PRESQUE ISLE)...AS A QUICK TRANSITION TO LIGHTER WINDS ARRIVES WITH HIGH PRESSURE. SLOW...BUT STEADY...IMPROVEMENT EXPECTED ACROSS ALL WATERS TODAY AS HIGH PRESSURE BUILDS INTO THE REGION. REMNANT GUSTY NORTHWEST WINDS AND CHOPPY WAVES WILL REQUIRE SCA/S FOR NEARLY ALL WATERS...BUT ALL GALE WARNINGS WILL BE ALLOWED TO EXPIRE BY 12Z. RAPID IMPROVEMENT EXPECTED LATE THIS AFTERNOON AND EVENING AS WINDS GO LIGHT UNDER OVERHEAD HIGH PRESSURE. GUSTY SOUTHEAST WINDS DEVELOP SUNDAY...POSSIBLY REQUIRING ADDITIONAL SCA/S FOR SOME NEARSHORE WATERS. && .APX WATCHES/WARNINGS/ADVISORIES... MI...NONE. LH...SMALL CRAFT ADVISORY UNTIL 5 PM EDT THIS AFTERNOON FOR LHZ345- 346-349. GALE WARNING UNTIL 2 PM EDT THIS AFTERNOON FOR LHZ347-348. LM...SMALL CRAFT ADVISORY UNTIL 5 PM EDT THIS AFTERNOON FOR LMZ323- 341-342-344>346. LS...SMALL CRAFT ADVISORY UNTIL 5 PM EDT THIS AFTERNOON FOR LSZ321- 322. && $$ UPDATE...SD SYNOPSIS...MR SHORT TERM...MB LONG TERM...MR AVIATION...TL MARINE...MB
AREA FORECAST DISCUSSION
NWS GAYLORD MI
1248 PM EDT SAT APR 20 2013 .SYNOPSIS... ISSUED AT 1058 AM EDT SAT APR 20 2013 LAKE EFFECT SNOW SHOWERS WILL CONTINUE TO IMPACT NORTHERN MICHIGAN THROUGH THE EARLY AFTERNOON HOURS...TARGETING THE TYPICAL SNOWBELT REGIONS OF EASTERN UPPER AND NORTHWEST LOWER MICHIGAN FOR THE MOST PERSISTENT AND HEAVIEST SNOW SHOWERS. HIGH PRESSURE WILL BEGIN TO SETTLE INTO THE GREAT LAKES REGION THIS AFTERNOON...BRINGING QUIET AND SEASONABLY CHILLY WEATHER TO NORTHERN MICHIGAN THROUGH THE REST OF THE WEEKEND. THE NEXT CHANCE OF RAIN ARRIVES FOR THE BEGINNING OF THE WORK WEEK AS SEVERAL WAVES OF LOW PRESSURE PUSH ACROSS THE REGION. && .UPDATE... ISSUED AT 1052 AM EDT SAT APR 20 2013 DOMINANT BAND OF MODERATE SNOWFALL CONTINUES TO DRIFT NE INTO OTSEGO...CHARLEVOIX AND NRN CRAWFORD COUNTIES. ALTHOUGH THE SNOWFALL IS RATHER IMPRESSIVE...ESPECIALLY FOR MID-LATE APRIL...THE TIME OF YEAR/SUN ANGLE IS NOT ALLOWING SNOW TO ACCUMULATE MUCH ANYMORE. WE DID HAVE REPORTS OF 1-2 INCHES OF SNOW OVERNIGHT...AND THESE AMOUNTS WILL NOT BE MET TODAY. THIS IS ALSO SUPPORTED BY AN EXPECTED TRANSITION TO MORE CELLULAR SHOWERS WITH INCREASED LOW LEVEL LAPSE RATES...A LOSS OF CYCLONIC CONVERGENCE AND DRY AIR ENTRAINMENT FROM INVADING HIGH PRESSURE UPSTREAM. WILL HAVE SOME PEEKS OF SUN AT TIMES...BUT SKIES ARE EXPECTED TO CLEAR MORE SO LATER THIS AFTERNOON...AS THE BETTER DRY AIR UPSTREAM FILLS IN BEHIND FINAL SFC TROUGH FROM NRN WISCONSIN THROUGH EASTERN LAKE SUPERIOR. WILL ALLOW WINTER HEADLINES TO EXPIRE...WITH IMPACTS FROM CONTINUED SNOW TO BE MINIMAL. ROADS WILL JUST BE WET FOR MOST ALL AREAS WITHIN THE ADVISORY. UPDATE ISSUED AT 717 AM EDT SAT APR 20 2013 MULTI-BAND LAKE EFFECT SNOW SHOWERS HAVE FULLY DEVELOPED ACROSS OUR CWA...WITH THE DOMINANT BAND EXTENDING FROM NEAR ALDEN TO KALKASKA. HEAVIER SNOW SHOWERS REMAIN EMBEDDED WITHIN THIS DOMINANT BAND...WITH SNOWFALL RATES OF AROUND AN INCH AN HOUR. WILL MAINTAIN THE LAKE SNOW ADVISORY FOR THE SNOWBELT REGION OF NW AND N CENTRAL LWR MICHIGAN THRU LATE MORNING...AT WHICH TIME SNOW SHOWERS SHOULD BEGIN TO BREAK DOWN AS HIGH PRESSURE AND DRIER AIR BEGIN TO BUILD INTO THE WRN GREAT LAKES. && .SHORT TERM...(TODAY THROUGH TONIGHT) ISSUED AT 300 AM EDT SAT APR 20 2013 WELL...THIS JUST ISN`T RIGHT FOR MID APRIL...COLD AND GUSTY NORTHWEST WINDS...WITH NUMEROUS GROUND WHITENING LAKE INDUCED SNOW SHOWERS TARGETING THE TRADITIONAL SNOW BELTS. CULPRIT BEHIND THIS NONSENSE IS ANOMALOUSLY DEEP TROUGH EXTENDING FROM THE MID MISSISSIPPI VALLEY UP THROUGH JAMES BAY. ATTENDANT BEHEMOTH SURFACE LOW NOW WELL TO OUR NORTHEAST UP ACROSS CENTRAL QUEBEC...WITH SURFACE TROUGH AXIS EXTENDING BACK SOUTHWEST INTO OUR AREA. COMBO OF DEEP MOISTURE AND MORE THAN PLENTIFUL OVER-WATER INSTABILITY (H8 TEMPERATURES DOWN AROUND -14/-15C PER RAP ANALYSIS) HELPING DRIVE THOSE LAKE SNOWS. FORECAST CONCERNS THROUGH THE SHORT TERM REAL CENTERED WITHIN THE FIRST HALF OF TODAY...CENTERING ON LINGERING LAKE INDUCED SNOW POTENTIAL AND POSSIBLE ADDITIONAL ACCUMULATIONS. RESPECTABLE LAKE SNOW PARAMETERS REMAIN IN PLACE EARLY ON THIS MORNING...WITH MORE THAN SUFFICIENT DELTA T/S AUGMENTED BY REMNANT DEEPER MOISTURE AND GOOD INVERSION LEVELS UP THROUGH H7 LEVELS. NNW (LAKE SUPERIOR) TO NW (NORTHERN LAKE MICHIGAN) FLOW REGIME WILL LOCKED IN BY SUNRISE...TARGETING THE NORTHWEST LOWER SNOWBELTS FOR THE MOST PERSISTENT AND HEAVIEST ACTIVITY. GIVEN FLOW...WOULD EXPECT BETTER LAKE SUPERIOR ACTIVITY TO REMAIN JUST WEST OF CHIPPEWA COUNTY. DECISIVE DOWNTURN IN LAKE SNOW PARAMETERS EXPECTED AFTER ABOUT 15Z...WITH STEADY LOSS OF SYNOPTIC MOISTURE SUPPORT AND LOWERING INVERSION LEVELS. DIURNAL DISRUPTION WILL ONLY HELP THE CAUSE..AS WILL DEEPENING OF SURFACE BASED DRY WEDGE. WOULD EXPECT SCATTERED LATE MORNING ACTIVITY TO COMPLETELY END BY EARLY AFTERNOON (YUP...SAID THAT BEFORE). UPSHOT TO ALL THE ABOVE...THINKING PERHAPS ANOTHER INCH OR SO IN NORTHWEST LOWER SNOWBELTS THIS MORNING...LEAVING THE INHERITED LAKE SNOW ADVISORY THROUGH ITS DURATION ENDING AT 15Z. LESS ACCUMULATION EXPECTED ELSEWHERE. DRYING REMAINS AGGRESSIVE THROUGH THE AFTERNOON...AND STILL EXPECT SKIES TO TREND PARTLY SUNNY TO SUNNY ALL AREAS. UNFORTUNATELY...EVEN MID APRIL SUN WILL DO LITTLE TO HELP THE TEMPERATURE CAUSE...WITH READINGS A SOLID 15 TO 20 DEGREES BELOW NORMAL. GUSTY NORTHWEST WINDS WILL SUBSIDE THROUGH THE DAY...BUT NOT BEFORE MAKING IT FEEL DOWNRIGHT COLD THROUGH THE EARLY AFTERNOON. MUCH QUIETER HEADING INTO TONIGHT AS DRYING BECOMES COMPLETE AND HIGH PRESSURE BUILDS DIRECTLY OVERHEAD. MOSTLY CLEAR SKIES...WITH PERHAPS A TOUCH OF HIGH CLOUDS LATE. RADIATION COOLING TRIFECTA... WITH QUICK LOSS OF WINDS...CLEAR SKIES..AND DRY LOW LEVELS. GUIDANCE CONTINUES TO TREND COLDER...NOW SHOWING THE TRADITIONAL ICE BOX LOCALES FLIRTING WITH THE UPPER SINGLE DIGITS. WILL NOT GO QUITE THIS AGGRESSIVE...USING LOWER TEENS FOR THE COLDER LOCATIONS. THESE NUMBERS FLIRT WITH RECORD LOWS FOR THE DAY...WITHIN A FEW DEGREES AT SEVERAL SITES. COULD EASILY SEE A RECORD TO TWO BROKEN BY SUNRISE SUNDAY. .LONG TERM...(SUNDAY THROUGH FRIDAY) ISSUED AT 300 AM EDT SAT APR 20 2013 .SUNDAY AND MONDAY...STRONG SURFACE HIGH PRESSURE CENTER SHIFTS EAST OF MICHIGAN BY 12Z SUNDAY. AFTER A FRIGID START TO THE DAY...WITH EARLY MORNING LOWS IN THE TEENS (WHICH IS ROUGHLY 20 DEGREES BELOW NORMAL)...TEMPS WILL REBOUND NICELY AS SOUTHERLY FLOW KICKS IN ON THE BACK SIDE OF THE HIGH CENTER. CLOUDS WILL INCREASE/THICKEN/LOWER FROM WEST TO EAST AS MAINLY MID/UPPER LEVEL MOISTURE BEGINS TO ADVECT INTO THE WRN GREAT LAKES IN ADVANCE OF A COLD FRONT DRIVING EAST THRU MINNESOTA. STILL APPEARS ANY PRECIP CHANCES WILL HOLD OFF UNTIL SUNDAY NIGHT...AND WILL BE CONFINED TO MAINLY ERN UPR MICHIGAN. ONCE THE COLD FRONT REACHES WRN UPR MICHIGAN AND WISCONSIN...UPPER LEVEL FLOW BECOMES NEARLY PARALLEL WITH THE FRONT ITSELF...WHICH WILL SLOW ITS EASTWARD PROGRESS. ALSO...A WAVE DEVELOPS ALONG THE FRONT...DEEPENING INTO A CLOSED LOW THAT DRIVES NE THRU THE STRAITS ON TUESDAY (MORE ON THIS BELOW). WITH THE SLOW EASTWARD PUSH OF THE FRONT AND ASSOCIATED MOISTURE...POPS WILL GRADUALLY SPREAD FROM ERN UPR MICHIGAN SUNDAY NIGHT INTO THE STRAITS AND ALONG THE LAKE MICHIGAN SHORELINE TO LEELANAU COUNTY ON MONDAY...AND THEN FINALLY MAKE SOME HEADWAY INTO NRN LWR MICHIGAN WEST OF A LINE FROM ROGERS CITY TO HTL LATE MONDAY NIGHT AS THAT WAVE (MENTIONED ABOVE) BEGINS TO LIFT INTO OUR CWA. AGAIN...TEMPS WILL RECOVER NICELY DURING THE FIRST PART OF NEXT WEEK THANKS TO WAA AHEAD OF THE SLOW COLD FRONT. HIGHS ON SUNDAY WILL WARM INTO THE MID 40S TO LOWER 50S...BUT WILL COOL BACK INTO THE 30S AT NIGHT. HOWEVER...PRECIP SUNDAY NIGHT IN ERN UPR MICHIGAN SHOULD BE ALL LIQUID PER NAM BUFR SOUNDINGS SHOWING A SURFACE-BASED ABOVE FREEZING LAYER THRU 850 MB. WAA FURTHER STRENGTHENS ON MONDAY...WITH TEMPS CLIMBING TO NEAR 50 IN ERN UPR MICHIGAN AND WELL INTO THE 50S TO NEAR 60 ACROSS NRN LWR MICHIGAN. COLD FRONT REMAINS WEST OF OUR CWA MONDAY NIGHT. TEMPS WILL COOLING MAINLY BACK INTO THE 40S MONDAY NIGHT...KEEPING ANY PRECIP ALL LIQUID. TUESDAY THRU FRIDAY...AS MENTIONED ABOVE...FIRST WAVE TRACKS ALONG THE COLD FRONT AND THRU THE STRAITS TUESDAY MORNING. THIS FEATURE COMBINED WITH DEEP MOISTURE WILL PRODUCE RAIN SHOWERS ACROSS MUCH OF OUR CWA ON TUESDAY. SECOND WAVE DEVELOPS ALONG THE FRONT AND TRACKS THRU SRN LWR MICHIGAN TUESDAY NIGHT...SPREADING ANOTHER AREA OF RAIN SHOWERS THRU MOST OF MICHIGAN. WITH AREA RIVERS ALREADY RUNNING HIGH FROM RECENT RAIN AND SNOWMELT...WILL NEED TO KEEP AN EYE ON THE POTENTIAL FOR HEAVY RAINFALL ESPECIALLY WITH THIS SECOND WAVE AS IT BEGINS TO TAP INTO GULF MOISTURE TUESDAY NIGHT. FOR NOW...WILL STICK WITH LIKELY POPS FOR TUESDAY AND TUESDAY NIGHT ACROSS MOST OF OUR CWA. PRECIP CHANCES DIMINISH ON WEDNESDAY AS THE FRONT EXITS TO THE EAST COAST AND SURFACE RIDGING BUILDS INTO MICHIGAN. A WEAK MOISTURE-STARVED NRN STREAM WAVE QUICKLY SWINGS THRU MICHIGAN THURSDAY...PRODUCING A QUICK CHANCE OF LIGHT RAIN. DEEPER MOISTURE WILL BEGIN TO ADVECT INTO THE WRN GREAT LAKES ON FRIDAY ONCE SOUTHERLY RETURN FLOW KICKS IN ON THE BACK SIDE OF HIGH PRESSURE. FIRST LOOK AT NEXT WEEKEND LOOKS UNSETTLED WITH NEAR NORMAL TEMPS IN THE 50S. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON) ISSUED AT 1247 PM EDT SAT APR 20 2013 ANY LINGERING LAKE EFFECT SNOW SHOWERS WILL END WITHIN THE FIRST FEW HOURS OF THE TAF PERIOD...AS HIGH PRESSURE BUILDS BEHIND THE DEPARTING STORM SYSTEM OVER QUEBEC. VFR CONDITIONS WILL PREVAIL THROUGHOUT THE ENTIRE TAF PERIOD FOR ALL TAF SITES. SKIES WILL CLEAR OUT THIS EVENING UNTIL A DECK OF MID-LEVEL CLOUDS OVERTAKE NORTHERN MICHIGAN TOMORROW MORNING. && .MARINE... ISSUED AT 1052 AM EDT SAT APR 20 2013 UPDATE...GALES CONTINUE ACROSS PRESQUE ISLE...AND WILL EXTEND THE GALE WARNING THROUGH 1-2 PM. ALL OTHER AREAS WILL BE IN THE SMALL CRAFT ADVISORY FOR THE DAY. HEADLINES ARE EXPECTED TO BE LIFTED MOST ALL AREAS BY EVENING (MAYBE NOT PRESQUE ISLE)...AS A QUICK TRANSITION TO LIGHTER WINDS ARRIVES WITH HIGH PRESSURE. SLOW...BUT STEADY...IMPROVEMENT EXPECTED ACROSS ALL WATERS TODAY AS HIGH PRESSURE BUILDS INTO THE REGION. REMNANT GUSTY NORTHWEST WINDS AND CHOPPY WAVES WILL REQUIRE SCA/S FOR NEARLY ALL WATERS...BUT ALL GALE WARNINGS WILL BE ALLOWED TO EXPIRE BY 12Z. RAPID IMPROVEMENT EXPECTED LATE THIS AFTERNOON AND EVENING AS WINDS GO LIGHT UNDER OVERHEAD HIGH PRESSURE. GUSTY SOUTHEAST WINDS DEVELOP SUNDAY...POSSIBLY REQUIRING ADDITIONAL SCA/S FOR SOME NEARSHORE WATERS. && .APX WATCHES/WARNINGS/ADVISORIES... MI...NONE. LH...SMALL CRAFT ADVISORY UNTIL 5 PM EDT THIS AFTERNOON FOR LHZ345- 346-349. GALE WARNING UNTIL 2 PM EDT THIS AFTERNOON FOR LHZ347-348. LM...SMALL CRAFT ADVISORY UNTIL 5 PM EDT THIS AFTERNOON FOR LMZ323- 341-342-344>346. LS...SMALL CRAFT ADVISORY UNTIL 5 PM EDT THIS AFTERNOON FOR LSZ321- 322. && $$ UPDATE...SD SYNOPSIS...TL SHORT TERM...MB LONG TERM...MR AVIATION...TL MARINE...MB
AREA FORECAST DISCUSSION
NWS GAYLORD MI
1054 AM EDT SAT APR 20 2013 .SYNOPSIS... ISSUED AT 300 AM EDT SAT APR 20 2013 LAKE EFFECT SNOW SHOWERS WILL CONTINUE TO IMPACT NORTHERN MICHIGAN THIS MORNING...TARGETING THE TYPICAL SNOWBELT REGIONS OF EASTERN UPPER AND NORTHWEST LOWER MICHIGAN FOR THE MOST PERSISTENT AND HEAVIEST SNOW SHOWERS. HIGH PRESSURE WILL BEGIN TO SETTLE INTO THE GREAT LAKES REGION THIS AFTERNOON...BRINGING QUIET AND SEASONABLY CHILLY WEATHER TO NORTHERN MICHIGAN THROUGH THE REST OF THE WEEKEND. THE NEXT CHANCE OF RAIN ARRIVES FOR THE BEGINNING OF THE WORK WEEK AS WAVES OF LOW PRESSURE PUSH ACROSS THE REGION. && .UPDATE... ISSUED AT 1052 AM EDT SAT APR 20 2013 DOMINANT BAND OF MODERATE SNOWFALL CONTINUES TO DRIFT NE INTO OTSEGO...CHARLEVOIX AND NRN CRAWFORD COUNTIES. ALTHOUGH THE SNOWFALL IS RATHER IMPRESSIVE...ESPECIALLY FOR MID-LATE APRIL...THE TIME OF YEAR/SUN ANGLE IS NOT ALLOWING SNOW TO ACCUMULATE MUCH ANYMORE. WE DID HAVE REPORTS OF 1-2 INCHES OF SNOW OVERNIGHT...AND THESE AMOUNTS WILL NOT BE MET TODAY. THIS IS ALSO SUPPORTED BY AN EXPECTED TRANSITION TO MORE CELLULAR SHOWERS WITH INCREASED LOW LEVEL LAPSE RATES...A LOSS OF CYCLONIC CONVERGENCE AND DRY AIR ENTRAINMENT FROM INVADING HIGH PRESSURE UPSTREAM. WILL AHVE SOME PEEKS OF SUN AT TIMES...BUT SKIES ARE EXPECTED TO CLEAR MORE SO LATER THIS AFTERNOON...AS THE BETTER DRY AIR UPSTREAM FILLS IN BEHIND FINAL SFC TROUGH FROM NRN WISCONSIN THROUGH EASTERN LAKE SUPERIOR. WILL ALLOW WINTER HEADLINES TO EXPIRE...WITH IMPACTS FROM CONTINUED SNOW TO BE MINIMAL. ROADS WILL JUST BE WET FOR MOST ALL AREAS WITHIN THE ADVISORY. UPDATE ISSUED AT 717 AM EDT SAT APR 20 2013 MULTI-BAND LAKE EFFECT SNOW SHOWERS HAVE FULLY DEVELOPED ACROSS OUR CWA...WITH THE DOMINANT BAND EXTENDING FROM NEAR ALDEN TO KALKASKA. HEAVIER SNOW SHOWERS REMAIN EMBEDDED WITHIN THIS DOMINANT BAND...WITH SNOWFALL RATES OF AROUND AN INCH AN HOUR. WILL MAINTAIN THE LAKE SNOW ADVISORY FOR THE SNOWBELT REGION OF NW AND N CENTRAL LWR MICHIGAN THRU LATE MORNING...AT WHICH TIME SNOW SHOWERS SHOULD BEGIN TO BREAK DOWN AS HIGH PRESSURE AND DRIER AIR BEGIN TO BUILD INTO THE WRN GREAT LAKES. && .SHORT TERM...(TODAY THROUGH TONIGHT) ISSUED AT 300 AM EDT SAT APR 20 2013 WELL...THIS JUST ISN`T RIGHT FOR MID APRIL...COLD AND GUSTY NORTHWEST WINDS...WITH NUMEROUS GROUND WHITENING LAKE INDUCED SNOW SHOWERS TARGETING THE TRADITIONAL SNOW BELTS. CULPRIT BEHIND THIS NONSENSE IS ANOMALOUSLY DEEP TROUGH EXTENDING FROM THE MID MISSISSIPPI VALLEY UP THROUGH JAMES BAY. ATTENDANT BEHEMOTH SURFACE LOW NOW WELL TO OUR NORTHEAST UP ACROSS CENTRAL QUEBEC...WITH SURFACE TROUGH AXIS EXTENDING BACK SOUTHWEST INTO OUR AREA. COMBO OF DEEP MOISTURE AND MORE THAN PLENTIFUL OVER-WATER INSTABILITY (H8 TEMPERATURES DOWN AROUND -14/-15C PER RAP ANALYSIS) HELPING DRIVE THOSE LAKE SNOWS. FORECAST CONCERNS THROUGH THE SHORT TERM REAL CENTERED WITHIN THE FIRST HALF OF TODAY...CENTERING ON LINGERING LAKE INDUCED SNOW POTENTIAL AND POSSIBLE ADDITIONAL ACCUMULATIONS. RESPECTABLE LAKE SNOW PARAMETERS REMAIN IN PLACE EARLY ON THIS MORNING...WITH MORE THAN SUFFICIENT DELTA T/S AUGMENTED BY REMNANT DEEPER MOISTURE AND GOOD INVERSION LEVELS UP THROUGH H7 LEVELS. NNW (LAKE SUPERIOR) TO NW (NORTHERN LAKE MICHIGAN) FLOW REGIME WILL LOCKED IN BY SUNRISE...TARGETING THE NORTHWEST LOWER SNOWBELTS FOR THE MOST PERSISTENT AND HEAVIEST ACTIVITY. GIVEN FLOW...WOULD EXPECT BETTER LAKE SUPERIOR ACTIVITY TO REMAIN JUST WEST OF CHIPPEWA COUNTY. DECISIVE DOWNTURN IN LAKE SNOW PARAMETERS EXPECTED AFTER ABOUT 15Z...WITH STEADY LOSS OF SYNOPTIC MOISTURE SUPPORT AND LOWERING INVERSION LEVELS. DIURNAL DISRUPTION WILL ONLY HELP THE CAUSE..AS WILL DEEPENING OF SURFACE BASED DRY WEDGE. WOULD EXPECT SCATTERED LATE MORNING ACTIVITY TO COMPLETELY END BY EARLY AFTERNOON (YUP...SAID THAT BEFORE). UPSHOT TO ALL THE ABOVE...THINKING PERHAPS ANOTHER INCH OR SO IN NORTHWEST LOWER SNOWBELTS THIS MORNING...LEAVING THE INHERITED LAKE SNOW ADVISORY THROUGH ITS DURATION ENDING AT 15Z. LESS ACCUMULATION EXPECTED ELSEWHERE. DRYING REMAINS AGGRESSIVE THROUGH THE AFTERNOON...AND STILL EXPECT SKIES TO TREND PARTLY SUNNY TO SUNNY ALL AREAS. UNFORTUNATELY...EVEN MID APRIL SUN WILL DO LITTLE TO HELP THE TEMPERATURE CAUSE...WITH READINGS A SOLID 15 TO 20 DEGREES BELOW NORMAL. GUSTY NORTHWEST WINDS WILL SUBSIDE THROUGH THE DAY...BUT NOT BEFORE MAKING IT FEEL DOWNRIGHT COLD THROUGH THE EARLY AFTERNOON. MUCH QUIETER HEADING INTO TONIGHT AS DRYING BECOMES COMPLETE AND HIGH PRESSURE BUILDS DIRECTLY OVERHEAD. MOSTLY CLEAR SKIES...WITH PERHAPS A TOUCH OF HIGH CLOUDS LATE. RADIATION COOLING TRIFECTA... WITH QUICK LOSS OF WINDS...CLEAR SKIES..AND DRY LOW LEVELS. GUIDANCE CONTINUES TO TREND COLDER...NOW SHOWING THE TRADITIONAL ICE BOX LOCALES FLIRTING WITH THE UPPER SINGLE DIGITS. WILL NOT GO QUITE THIS AGGRESSIVE...USING LOWER TEENS FOR THE COLDER LOCATIONS. THESE NUMBERS FLIRT WITH RECORD LOWS FOR THE DAY...WITHIN A FEW DEGREES AT SEVERAL SITES. COULD EASILY SEE A RECORD TO TWO BROKEN BY SUNRISE SUNDAY. .LONG TERM...(SUNDAY THROUGH FRIDAY) ISSUED AT 300 AM EDT SAT APR 20 2013 .SUNDAY AND MONDAY...STRONG SURFACE HIGH PRESSURE CENTER SHIFTS EAST OF MICHIGAN BY 12Z SUNDAY. AFTER A FRIGID START TO THE DAY...WITH EARLY MORNING LOWS IN THE TEENS (WHICH IS ROUGHLY 20 DEGREES BELOW NORMAL)...TEMPS WILL REBOUND NICELY AS SOUTHERLY FLOW KICKS IN ON THE BACK SIDE OF THE HIGH CENTER. CLOUDS WILL INCREASE/THICKEN/LOWER FROM WEST TO EAST AS MAINLY MID/UPPER LEVEL MOISTURE BEGINS TO ADVECT INTO THE WRN GREAT LAKES IN ADVANCE OF A COLD FRONT DRIVING EAST THRU MINNESOTA. STILL APPEARS ANY PRECIP CHANCES WILL HOLD OFF UNTIL SUNDAY NIGHT...AND WILL BE CONFINED TO MAINLY ERN UPR MICHIGAN. ONCE THE COLD FRONT REACHES WRN UPR MICHIGAN AND WISCONSIN...UPPER LEVEL FLOW BECOMES NEARLY PARALLEL WITH THE FRONT ITSELF...WHICH WILL SLOW ITS EASTWARD PROGRESS. ALSO...A WAVE DEVELOPS ALONG THE FRONT...DEEPENING INTO A CLOSED LOW THAT DRIVES NE THRU THE STRAITS ON TUESDAY (MORE ON THIS BELOW). WITH THE SLOW EASTWARD PUSH OF THE FRONT AND ASSOCIATED MOISTURE...POPS WILL GRADUALLY SPREAD FROM ERN UPR MICHIGAN SUNDAY NIGHT INTO THE STRAITS AND ALONG THE LAKE MICHIGAN SHORELINE TO LEELANAU COUNTY ON MONDAY...AND THEN FINALLY MAKE SOME HEADWAY INTO NRN LWR MICHIGAN WEST OF A LINE FROM ROGERS CITY TO HTL LATE MONDAY NIGHT AS THAT WAVE (MENTIONED ABOVE) BEGINS TO LIFT INTO OUR CWA. AGAIN...TEMPS WILL RECOVER NICELY DURING THE FIRST PART OF NEXT WEEK THANKS TO WAA AHEAD OF THE SLOW COLD FRONT. HIGHS ON SUNDAY WILL WARM INTO THE MID 40S TO LOWER 50S...BUT WILL COOL BACK INTO THE 30S AT NIGHT. HOWEVER...PRECIP SUNDAY NIGHT IN ERN UPR MICHIGAN SHOULD BE ALL LIQUID PER NAM BUFR SOUNDINGS SHOWING A SURFACE-BASED ABOVE FREEZING LAYER THRU 850 MB. WAA FURTHER STRENGTHENS ON MONDAY...WITH TEMPS CLIMBING TO NEAR 50 IN ERN UPR MICHIGAN AND WELL INTO THE 50S TO NEAR 60 ACROSS NRN LWR MICHIGAN. COLD FRONT REMAINS WEST OF OUR CWA MONDAY NIGHT. TEMPS WILL COOLING MAINLY BACK INTO THE 40S MONDAY NIGHT...KEEPING ANY PRECIP ALL LIQUID. TUESDAY THRU FRIDAY...AS MENTIONED ABOVE...FIRST WAVE TRACKS ALONG THE COLD FRONT AND THRU THE STRAITS TUESDAY MORNING. THIS FEATURE COMBINED WITH DEEP MOISTURE WILL PRODUCE RAIN SHOWERS ACROSS MUCH OF OUR CWA ON TUESDAY. SECOND WAVE DEVELOPS ALONG THE FRONT AND TRACKS THRU SRN LWR MICHIGAN TUESDAY NIGHT...SPREADING ANOTHER AREA OF RAIN SHOWERS THRU MOST OF MICHIGAN. WITH AREA RIVERS ALREADY RUNNING HIGH FROM RECENT RAIN AND SNOWMELT...WILL NEED TO KEEP AN EYE ON THE POTENTIAL FOR HEAVY RAINFALL ESPECIALLY WITH THIS SECOND WAVE AS IT BEGINS TO TAP INTO GULF MOISTURE TUESDAY NIGHT. FOR NOW...WILL STICK WITH LIKELY POPS FOR TUESDAY AND TUESDAY NIGHT ACROSS MOST OF OUR CWA. PRECIP CHANCES DIMINISH ON WEDNESDAY AS THE FRONT EXITS TO THE EAST COAST AND SURFACE RIDGING BUILDS INTO MICHIGAN. A WEAK MOISTURE-STARVED NRN STREAM WAVE QUICKLY SWINGS THRU MICHIGAN THURSDAY...PRODUCING A QUICK CHANCE OF LIGHT RAIN. DEEPER MOISTURE WILL BEGIN TO ADVECT INTO THE WRN GREAT LAKES ON FRIDAY ONCE SOUTHERLY RETURN FLOW KICKS IN ON THE BACK SIDE OF HIGH PRESSURE. FIRST LOOK AT NEXT WEEKEND LOOKS UNSETTLED WITH NEAR NORMAL TEMPS IN THE 50S. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SUNDAY MORNING) ISSUED AT 717 AM EDT SAT APR 20 2013 THE MOST PERSISTENT AND HEAVIEST LAKE EFFECT SNOW SHOWERS WILL CONTINUE TO IMPACT LOCATIONS BETWEEN PLN...TVC AND APN. OVERALL CONDITIONS AT OUR TAF SITES WILL BE VFR...OCCASIONALLY DROPPING TO MVFR WITHIN SNOW SHOWERS THIS MORNING. SNOW SHOWERS WILL END BY EARLY AFTERNOON AS HIGH PRESSURE BEGINS TO BUILD INTO THE WRN GREAT LAKES REGION...WITH DECREASING CLOUDS THEREAFTER. GUSTY NW WINDS WILL ALSO DIMINISH LATER THIS AFTERNOON AND EVENING. && .MARINE... ISSUED AT 1052 AM EDT SAT APR 20 2013 UPDATE...GALES CONTINUE ACROSS PRESQUE ISLE...AND WILL EXTEND THE GALE WARNING THROUGH 1-2 PM. ALL OTHER AREAS WILL BE IN THE SMALL CRAFT ADVISORY FOR THE DAY. HEADLINES ARE EXPECTED TO BE LIFTED MOST ALL AREAS BY EVENING (MAYBE NOT PRESQUE ISLE)...AS A QUICK TRANSITION TO LIGHTER WINDS ARRIVES WITH HIGH PRESSURE. SLOW...BUT STEADY...IMPROVEMENT EXPECTED ACROSS ALL WATERS TODAY AS HIGH PRESSURE BUILDS INTO THE REGION. REMNANT GUSTY NORTHWEST WINDS AND CHOPPY WAVES WILL REQUIRE SCA/S FOR NEARLY ALL WATERS...BUT ALL GALE WARNINGS WILL BE ALLOWED TO EXPIRE BY 12Z. RAPID IMPROVEMENT EXPECTED LATE THIS AFTERNOON AND EVENING AS WINDS GO LIGHT UNDER OVERHEAD HIGH PRESSURE. GUSTY SOUTHEAST WINDS DEVELOP SUNDAY...POSSIBLY REQUIRING ADDITIONAL SCA/S FOR SOME NEARSHORE WATERS. && .APX WATCHES/WARNINGS/ADVISORIES... MI...NONE. LH...SMALL CRAFT ADVISORY UNTIL 5 PM EDT THIS AFTERNOON FOR LHZ345- 346-349. GALE WARNING UNTIL 2 PM EDT THIS AFTERNOON FOR LHZ347-348. LM...SMALL CRAFT ADVISORY UNTIL 5 PM EDT THIS AFTERNOON FOR LMZ323- 341-342-344>346. LS...SMALL CRAFT ADVISORY UNTIL 5 PM EDT THIS AFTERNOON FOR LSZ321- 322. && $$ UPDATE...SD SYNOPSIS...MR SHORT TERM...MB LONG TERM...MR AVIATION...MR MARINE...MB
AREA FORECAST DISCUSSION
NWS GAYLORD MI
718 AM EDT SAT APR 20 2013 .SYNOPSIS... ISSUED AT 300 AM EDT SAT APR 20 2013 LAKE EFFECT SNOW SHOWERS WILL CONTINUE TO IMPACT NORTHERN MICHIGAN THIS MORNING...TARGETING THE TYPICAL SNOWBELT REGIONS OF EASTERN UPPER AND NORTHWEST LOWER MICHIGAN FOR THE MOST PERSISTENT AND HEAVIEST SNOW SHOWERS. HIGH PRESSURE WILL BEGIN TO SETTLE INTO THE GREAT LAKES REGION THIS AFTERNOON...BRINGING QUIET AND SEASONABLY CHILLY WEATHER TO NORTHERN MICHIGAN THROUGH THE REST OF THE WEEKEND. THE NEXT CHANCE OF RAIN ARRIVES FOR THE BEGINNING OF THE WORK WEEK AS WAVES OF LOW PRESSURE PUSH ACROSS THE REGION. && .UPDATE... ISSUED AT 717 AM EDT SAT APR 20 2013 MULTI-BAND LAKE EFFECT SNOW SHOWERS HAVE FULLY DEVELOPED ACROSS OUR CWA...WITH THE DOMINANT BAND EXTENDING FROM NEAR ALDEN TO KALKASKA. HEAVIER SNOW SHOWERS REMAIN EMBEDDED WITHIN THIS DOMINANT BAND...WITH SNOWFALL RATES OF AROUND AN INCH AN HOUR. WILL MAINTAIN THE LAKE SNOW ADVISORY FOR THE SNOWBELT REGION OF NW AND N CENTRAL LWR MICHIGAN THRU LATE MORNING...AT WHICH TIME SNOW SHOWERS SHOULD BEGIN TO BREAK DOWN AS HIGH PRESSURE AND DRIER AIR BEGIN TO BUILD INTO THE WRN GREAT LAKES. && .SHORT TERM...(TODAY THROUGH TONIGHT) ISSUED AT 300 AM EDT SAT APR 20 2013 WELL...THIS JUST ISN`T RIGHT FOR MID APRIL...COLD AND GUSTY NORTHWEST WINDS...WITH NUMEROUS GROUND WHITENING LAKE INDUCED SNOW SHOWERS TARGETING THE TRADITIONAL SNOW BELTS. CULPRIT BEHIND THIS NONSENSE IS ANOMALOUSLY DEEP TROUGH EXTENDING FROM THE MID MISSISSIPPI VALLEY UP THROUGH JAMES BAY. ATTENDANT BEHEMOTH SURFACE LOW NOW WELL TO OUR NORTHEAST UP ACROSS CENTRAL QUEBEC...WITH SURFACE TROUGH AXIS EXTENDING BACK SOUTHWEST INTO OUR AREA. COMBO OF DEEP MOISTURE AND MORE THAN PLENTIFUL OVER-WATER INSTABILITY (H8 TEMPERATURES DOWN AROUND -14/-15C PER RAP ANALYSIS) HELPING DRIVE THOSE LAKE SNOWS. FORECAST CONCERNS THROUGH THE SHORT TERM REAL CENTERED WITHIN THE FIRST HALF OF TODAY...CENTERING ON LINGERING LAKE INDUCED SNOW POTENTIAL AND POSSIBLE ADDITIONAL ACCUMULATIONS. RESPECTABLE LAKE SNOW PARAMETERS REMAIN IN PLACE EARLY ON THIS MORNING...WITH MORE THAN SUFFICIENT DELTA T/S AUGMENTED BY REMNANT DEEPER MOISTURE AND GOOD INVERSION LEVELS UP THROUGH H7 LEVELS. NNW (LAKE SUPERIOR) TO NW (NORTHERN LAKE MICHIGAN) FLOW REGIME WILL LOCKED IN BY SUNRISE...TARGETING THE NORTHWEST LOWER SNOWBELTS FOR THE MOST PERSISTENT AND HEAVIEST ACTIVITY. GIVEN FLOW...WOULD EXPECT BETTER LAKE SUPERIOR ACTIVITY TO REMAIN JUST WEST OF CHIPPEWA COUNTY. DECISIVE DOWNTURN IN LAKE SNOW PARAMETERS EXPECTED AFTER ABOUT 15Z...WITH STEADY LOSS OF SYNOPTIC MOISTURE SUPPORT AND LOWERING INVERSION LEVELS. DIURNAL DISRUPTION WILL ONLY HELP THE CAUSE..AS WILL DEEPENING OF SURFACE BASED DRY WEDGE. WOULD EXPECT SCATTERED LATE MORNING ACTIVITY TO COMPLETELY END BY EARLY AFTERNOON (YUP...SAID THAT BEFORE). UPSHOT TO ALL THE ABOVE...THINKING PERHAPS ANOTHER INCH OR SO IN NORTHWEST LOWER SNOWBELTS THIS MORNING...LEAVING THE INHERITED LAKE SNOW ADVISORY THROUGH ITS DURATION ENDING AT 15Z. LESS ACCUMULATION EXPECTED ELSEWHERE. DRYING REMAINS AGGRESSIVE THROUGH THE AFTERNOON...AND STILL EXPECT SKIES TO TREND PARTLY SUNNY TO SUNNY ALL AREAS. UNFORTUNATELY...EVEN MID APRIL SUN WILL DO LITTLE TO HELP THE TEMPERATURE CAUSE...WITH READINGS A SOLID 15 TO 20 DEGREES BELOW NORMAL. GUSTY NORTHWEST WINDS WILL SUBSIDE THROUGH THE DAY...BUT NOT BEFORE MAKING IT FEEL DOWNRIGHT COLD THROUGH THE EARLY AFTERNOON. MUCH QUIETER HEADING INTO TONIGHT AS DRYING BECOMES COMPLETE AND HIGH PRESSURE BUILDS DIRECTLY OVERHEAD. MOSTLY CLEAR SKIES...WITH PERHAPS A TOUCH OF HIGH CLOUDS LATE. RADIATION COOLING TRIFECTA... WITH QUICK LOSS OF WINDS...CLEAR SKIES..AND DRY LOW LEVELS. GUIDANCE CONTINUES TO TREND COLDER...NOW SHOWING THE TRADITIONAL ICE BOX LOCALES FLIRTING WITH THE UPPER SINGLE DIGITS. WILL NOT GO QUITE THIS AGGRESSIVE...USING LOWER TEENS FOR THE COLDER LOCATIONS. THESE NUMBERS FLIRT WITH RECORD LOWS FOR THE DAY...WITHIN A FEW DEGREES AT SEVERAL SITES. COULD EASILY SEE A RECORD TO TWO BROKEN BY SUNRISE SUNDAY. .LONG TERM...(SUNDAY THROUGH FRIDAY) ISSUED AT 300 AM EDT SAT APR 20 2013 .SUNDAY AND MONDAY...STRONG SURFACE HIGH PRESSURE CENTER SHIFTS EAST OF MICHIGAN BY 12Z SUNDAY. AFTER A FRIGID START TO THE DAY...WITH EARLY MORNING LOWS IN THE TEENS (WHICH IS ROUGHLY 20 DEGREES BELOW NORMAL)...TEMPS WILL REBOUND NICELY AS SOUTHERLY FLOW KICKS IN ON THE BACK SIDE OF THE HIGH CENTER. CLOUDS WILL INCREASE/THICKEN/LOWER FROM WEST TO EAST AS MAINLY MID/UPPER LEVEL MOISTURE BEGINS TO ADVECT INTO THE WRN GREAT LAKES IN ADVANCE OF A COLD FRONT DRIVING EAST THRU MINNESOTA. STILL APPEARS ANY PRECIP CHANCES WILL HOLD OFF UNTIL SUNDAY NIGHT...AND WILL BE CONFINED TO MAINLY ERN UPR MICHIGAN. ONCE THE COLD FRONT REACHES WRN UPR MICHIGAN AND WISCONSIN...UPPER LEVEL FLOW BECOMES NEARLY PARALLEL WITH THE FRONT ITSELF...WHICH WILL SLOW ITS EASTWARD PROGRESS. ALSO...A WAVE DEVELOPS ALONG THE FRONT...DEEPENING INTO A CLOSED LOW THAT DRIVES NE THRU THE STRAITS ON TUESDAY (MORE ON THIS BELOW). WITH THE SLOW EASTWARD PUSH OF THE FRONT AND ASSOCIATED MOISTURE...POPS WILL GRADUALLY SPREAD FROM ERN UPR MICHIGAN SUNDAY NIGHT INTO THE STRAITS AND ALONG THE LAKE MICHIGAN SHORELINE TO LEELANAU COUNTY ON MONDAY...AND THEN FINALLY MAKE SOME HEADWAY INTO NRN LWR MICHIGAN WEST OF A LINE FROM ROGERS CITY TO HTL LATE MONDAY NIGHT AS THAT WAVE (MENTIONED ABOVE) BEGINS TO LIFT INTO OUR CWA. AGAIN...TEMPS WILL RECOVER NICELY DURING THE FIRST PART OF NEXT WEEK THANKS TO WAA AHEAD OF THE SLOW COLD FRONT. HIGHS ON SUNDAY WILL WARM INTO THE MID 40S TO LOWER 50S...BUT WILL COOL BACK INTO THE 30S AT NIGHT. HOWEVER...PRECIP SUNDAY NIGHT IN ERN UPR MICHIGAN SHOULD BE ALL LIQUID PER NAM BUFR SOUNDINGS SHOWING A SURFACE-BASED ABOVE FREEZING LAYER THRU 850 MB. WAA FURTHER STRENGTHENS ON MONDAY...WITH TEMPS CLIMBING TO NEAR 50 IN ERN UPR MICHIGAN AND WELL INTO THE 50S TO NEAR 60 ACROSS NRN LWR MICHIGAN. COLD FRONT REMAINS WEST OF OUR CWA MONDAY NIGHT. TEMPS WILL COOLING MAINLY BACK INTO THE 40S MONDAY NIGHT...KEEPING ANY PRECIP ALL LIQUID. TUESDAY THRU FRIDAY...AS MENTIONED ABOVE...FIRST WAVE TRACKS ALONG THE COLD FRONT AND THRU THE STRAITS TUESDAY MORNING. THIS FEATURE COMBINED WITH DEEP MOISTURE WILL PRODUCE RAIN SHOWERS ACROSS MUCH OF OUR CWA ON TUESDAY. SECOND WAVE DEVELOPS ALONG THE FRONT AND TRACKS THRU SRN LWR MICHIGAN TUESDAY NIGHT...SPREADING ANOTHER AREA OF RAIN SHOWERS THRU MOST OF MICHIGAN. WITH AREA RIVERS ALREADY RUNNING HIGH FROM RECENT RAIN AND SNOWMELT...WILL NEED TO KEEP AN EYE ON THE POTENTIAL FOR HEAVY RAINFALL ESPECIALLY WITH THIS SECOND WAVE AS IT BEGINS TO TAP INTO GULF MOISTURE TUESDAY NIGHT. FOR NOW...WILL STICK WITH LIKELY POPS FOR TUESDAY AND TUESDAY NIGHT ACROSS MOST OF OUR CWA. PRECIP CHANCES DIMINISH ON WEDNESDAY AS THE FRONT EXITS TO THE EAST COAST AND SURFACE RIDGING BUILDS INTO MICHIGAN. A WEAK MOISTURE-STARVED NRN STREAM WAVE QUICKLY SWINGS THRU MICHIGAN THURSDAY...PRODUCING A QUICK CHANCE OF LIGHT RAIN. DEEPER MOISTURE WILL BEGIN TO ADVECT INTO THE WRN GREAT LAKES ON FRIDAY ONCE SOUTHERLY RETURN FLOW KICKS IN ON THE BACK SIDE OF HIGH PRESSURE. FIRST LOOK AT NEXT WEEKEND LOOKS UNSETTLED WITH NEAR NORMAL TEMPS IN THE 50S. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z SUNDAY MORNING) ISSUED AT 717 AM EDT SAT APR 20 2013 THE MOST PERSISTENT AND HEAVIEST LAKE EFFECT SNOW SHOWERS WILL CONTINUE TO IMPACT LOCATIONS BETWEEN PLN...TVC AND APN. OVERALL CONDITIONS AT OUR TAF SITES WILL BE VFR...OCCASIONALLY DROPPING TO MVFR WITHIN SNOW SHOWERS THIS MORNING. SNOW SHOWERS WILL END BY EARLY AFTERNOON AS HIGH PRESSURE BEGINS TO BUILD INTO THE WRN GREAT LAKES REGION...WITH DECREASING CLOUDS THEREAFTER. GUSTY NW WINDS WILL ALSO DIMINISH LATER THIS AFTERNOON AND EVENING. && .MARINE... ISSUED AT 300 AM EDT SAT APR 20 2013 SLOW...BUT STEADY...IMPROVEMENT EXPECTED ACROSS ALL WATERS TODAY AS HIGH PRESSURE BUILDS INTO THE REGION. REMNANT GUSTY NORTHWEST WINDS AND CHOPPY WAVES WILL REQUIRE SCA/S FOR NEARLY ALL WATERS...BUT ALL GALE WARNINGS WILL BE ALLOWED TO EXPIRE BY 12Z. RAPID IMPROVEMENT EXPECTED LATE THIS AFTERNOON AND EVENING AS WINDS GO LIGHT UNDER OVERHEAD HIGH PRESSURE. GUSTY SOUTHEAST WINDS DEVELOP SUNDAY...POSSIBLY REQUIRING ADDITIONAL SCA/S FOR SOME NEARSHORE WATERS. && .APX WATCHES/WARNINGS/ADVISORIES... MI...LAKE EFFECT SNOW ADVISORY UNTIL 11 AM EDT THIS MORNING FOR MIZ021-022-027-028. LH...GALE WARNING UNTIL 11 AM EDT THIS MORNING FOR LHZ345>349. LM...SMALL CRAFT ADVISORY UNTIL 5 PM EDT THIS AFTERNOON FOR LMZ323- 341-342-344>346. LS...SMALL CRAFT ADVISORY UNTIL 5 PM EDT THIS AFTERNOON FOR LSZ321- 322. && $$ UPDATE...MR SYNOPSIS...MR SHORT TERM...MB LONG TERM...MR AVIATION...MR MARINE...MB
AREA FORECAST DISCUSSION
NWS TWIN CITIES/CHANHASSEN MN
118 PM CDT SAT APR 20 2013 .SHORT TERM...(THIS EVENING THROUGH SUNDAY) ISSUED AT 335 AM CDT SAT APR 20 2013 THERE ARE A FEW FORECAST ISSUES OF CONCERN OVER THE NEXT SEVERAL DAYS... AND THE S-WORD IS INVOLVED YET AGAIN. IN THE BIG PICTURE... WATER VAPOR IMAGERY AND RAP UPPER AIR ANALYSES CONTINUE TO SHOW AN ALL TOO FAMILIAR PATTERN OF RIDGING OFF THE WEST COAST WITH NORTHWEST UPPER FLOW INTO OUR AREA. THE UPPER TROUGH ASSOCIATED WITH OUR RECENT STORM HAS PUSHED EAST INTO THE GREAT LAKES... AND WE NOW AWAIT THE ARRIVAL OF SHORTWAVE ENERGY DROPPING SOUTHEAST INTO ALBERTA AND ANOTHER SHORTWAVE NEAR THE NEVADA/UTAH BORDER. THE SOUTHERN FEATURE WON/T DIRECTLY EFFECT US... ALTHOUGH IT WILL HELP IN PUSHING THE ELEVATED WARM FRONT THROUGH THE AREA LATE TONIGHT AND SUNDAY. THE NORTHERN WAVE WILL PASS BY TO OUR NORTH... BUT WILL STILL MANAGE TO DRAG A COLD FRONT BACK THROUGH THE AREA SUNDAY NIGHT. A SHORTWAVE FARTHER UPSTREAM OVER ALASKA WILL DROP INTO THE MEAN TROUGH SUNDAY INTO MONDAY AND MAKE THE TURN TO OUR SOUTH... LIFTING NORTHEAST THROUGH THE REGION LATE MONDAY INTO TUESDAY. THE GFS AND ECMWF HAVE COME INTO DECENT AGREEMENT IN THEIR HANDLING OF THIS FEATURE... ALTHOUGH THE ECMWF IS A BIT FARTHER WEST IN ITS PLACEMENT OF THE INVERTED TROUGH AND EVENTUAL SURFACE LOW TRACK... AND HAS THE RAIN/SNOW LINE A BIT FARTHER WEST AS A RESULT. FOR NOW... A COMPROMISE BETWEEN THE GFS AND ECMWF SEEMS TO BE THE MOST LOGICAL COURSE OF ACTION... ESPECIALLY GIVEN THE ECMWF SHIFTED TOWARD THE GFS SOLUTION WITH ITS MOST RECENT RUN. LOOK FOR THE SURFACE RIDGE TO DRIFT EAST ACROSS THE AREA TODAY... WITH SOME INCREASE IN MID-HIGH CLOUDS THROUGH THE DAY AS WE GET INTO RETURN FLOW AND SEE A BIT OF AN UPPER LEVEL RIDGE WORK ACROSS THE AREA. WARM ADVECTION PCPN SHOULD GET GOING TO OUR SOUTHWEST LATE THIS AFTERNOON AND SPREAD EAST ACROSS THE AREA TONIGHT. THE 290-295K ISENTROPIC LAYER OFF THE NAM AND GFS DOES A NICE JOB OF HIGHLIGHTING THE TIMING OF THINGS AND SUGGESTING WHERE THE BEST PCPN SHOULD OCCUR. FORECAST SOUNDINGS ARE GENERALLY SUPPORTIVE OF SNOW... AT LEAST INITIALLY... BEFORE WE SEE A BIT OF A WARM FRONT LIFT THROUGH SUNDAY MORNING AND CHANGE ANY LINGERING PCPN OVER TO RAIN. BEFORE THAT OCCURS THERE COULD BE SOME LIGHT ACCUMULATIONS... ALTHOUGH WOULDN/T EXPECT MUCH MORE THAN AN INCH WITH PCPN TOTALS GENERALLY MAXING OUT FROM ONE TO TWO TENTHS OF AN INCH. AS THE SHORTWAVE MOVES BY TO OUR NORTH TONIGHT WE WILL SEE A COLD FRONT MOVE THROUGH THE AREA. EXACTLY HOW FAR THAT BOUNDARY GETS DRAGGED SOUTHEAST WILL DICTATE WHERE THE BAROCLINIC ZONE... AND EVENTUALLY SURFACE LOW TRACK... WILL SETUP FOR THE MONDAY STORM SYSTEM. .LONG TERM...(SUNDAY NIGHT THROUGH SATURDAY) ISSUED AT 335 AM CDT SAT APR 20 2013 THE NAM APPEARS TOO FAR EAST... MUCH LIKE WITH THE LAST SYSTEM... WHILE THE ECMWF IS THE WESTERNMOST OF THE DETERMINISTIC SOLUTIONS. THE SREF MEAN IS EAST OF THE NAM AND WILL BE DISCOUNTED AT THIS POINT. ALL IN ALL... A BLEND OF THE GFS AND ECMWF LOOKS TO BE THE BEST GUESS AT THIS POINT... WHICH MEANS WE WILL ONCE AGAIN BE DEALING WITH A DECENT PCPN EVENT ACROSS THE AREA WITH MANY LOCATIONS LIKELY SEEING THINGS OCCUR IN THE FORM OF SNOW. FRONTOGENESIS IN THE 700-800MB LAYER REALLY GETS GOING MONDAY AFTERNOON... WITH WEAKLY STABLE AIR IN THE ZONE OF BEST FORCING... SO EXPECT TO SEE GOOD UPWARD MOTION IN ASSOCIATION WITH THE LOW- MID LEVEL DEFORMATION AND FRONTOGENESIS. THE GFS AND ECMWF BOTH MANAGE TO SQUEEZE OUT 0.5-0.75 INCHES OR SO OF PCPN... SO THERE IS DEFINITELY THE POTENTIAL FOR SEVERAL INCHES OF SNOW AND PERHAPS A BIT MORE DEPENDING ON WHERE THE RAIN/SNOW LINE SETS UP WITH RESPECT TO THE HEAVIEST PCPN. INCLUDED SOME 2 TO 5 INCH AMOUNTS IN THE FORECAST GRIDS... WITH A RAIN/SNOW LINE SIMILAR TO THE LAST EVENT... BUT CERTAINLY DON/T HAVE HIGH CONFIDENCE AT THIS POINT. SOME LIGHT PCPN COULD LINGER INTO TUESDAY ACROSS THE EAST... BUT ANY ADDITIONAL PCPN AMOUNTS SHOULD BE LIGHT. HIGH PRESSURE WILL THEN BUILD INTO THE AREA THROUGH WEDNESDAY... WITH SOME PERIODIC PCPN CHANCES RETURNING TO THE REGION FOR THE LATTER HALF OF THE WEEK AS A FEW QUICKLY MOVING SHORTWAVES EMBEDDED IN THE WEST/NORTHWEST FLOW ROTATE THROUGH THE AREA. PCPN-TYPE WITH EACH SYSTEM WILL DEPEND TO SOME EXTENT ON THE TIME OF DAY... SINCE TEMPERATURES ALOFT WILL BE SUFFICIENTLY COLD FOR SNOW UNTIL FRIDAY... BUT BOUNDARY LAYER TEMPERATURES DURING THE DAYTIME SHOULD KEEP THINGS RAIN. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON) ISSUED AT 1258 PM CDT SAT APR 20 2013 VFR EXPECTED FOR THE FIRST 9-12 HOURS OF THE TAF. MODERATE SNOW CURRENTLY IN SD WILL MOVE EAST WITH TIME AND EVENTUALLY PRODUCE MVFR TO IFR CONDITIONS IN MN FROM 04-09Z TONIGHT. SNOW PERIOD SHOULD BE RELATIVELY BRIEF...FOLLOWED BY A LULL...AND THEN DETERIORATING CONDITIONS AND A LIGHT TO MODERATE BAND OF RAIN DURING THE DAY ON SUNDAY. KMSP... NO PROBLEMS THROUGH THE REMAINDER OF THE DAY TODAY. LOOK FOR A 2-3 HOUR WINDOW FOR LIGHT SNOW LATE TONIGHT. MVFR CONDITIONS POSSIBLE WITH VERY MINOR SNOW ACCUMULATION. RAIN AND MVFR/IFR IS EXPECTED ON SUNDAY...THERE WILL BE A LONGER PERIOD OF RAIN...PERHAPS 3-6 HOURS. /OUTLOOK FOR KMSP/ SUN NGT...MVFR WITH -RA/-SN PSBL. WIND BCMG NW 5 TO 10 KTS. MON...MVFR WITH -SN. IFR CIGS PSBL. NW WIND 15-20 KTS. TUE...VFR. NW WIND 10-15 KTS. && .MPX WATCHES/WARNINGS/ADVISORIES... MN...NONE. WI...NONE. && $$ SHORT TERM...WRB LONG TERM...TRH AVIATION...CLF
AREA FORECAST DISCUSSION
NWS BINGHAMTON NY
352 PM EDT SAT APR 20 2013 .SYNOPSIS... A BRISK AND COLD NORTHWEST FLOW OF AIR WILL BRING SCATTERED LIGHT RAIN AND SNOW SHOWERS TO THE REGION INTO THIS EVENING. HIGH PRESSURE WILL THEN BUILD IN ACROSS THE REGION LATE TONIGHT, WITH CHILLY TEMPERATURES FOR THIS TIME OF YEAR. THE HIGH WILL LINGER OVER THE NORTHEAST UNITED STATES INTO TUESDAY, WITH FAIR SKIES AND SLOWLY MODERATING TEMPERATURES. && .NEAR TERM /UNTIL 6 AM SUNDAY MORNING/... 330 PM UPDATE... SHORT WAVE MOVING THROUGH NOW WITH SOME FLURRIES AND SPRINKLES ACROSS MOST OF THE CWA. COLD AIR ADVECTION OCCURRING BEHIND A SFC TROF. 850 MB TEMPS FALL TO -12C WHICH IS COLD ENOUGH FOR AT LEAST LAKE EFFECT CLOUDS AND PROBABLY SNOW FLURRIES TOO. WITH THE WARM GROUND IT WILL BE DIFFICULT FOR ANY SNOW TO STICK. AS USUAL MOST LIKELY AT THE HIGHEST ELEVATIONS OF THE UPPER SUSQUEHANNA AND TUG HILL. SNOW AMOUNTS DUSTING AT MOST. LOW LEVEL FLOW SHIFTS FROM WEST TO NW THIS EVENING KEEPING CLOUDS IN NY AND THE NRN TIER OF PA. WINDS WILL CONTINUE TO GUST INTO THE EVENING THEN FALL AS A LARGE SURFACE HIGH MOVES IN LATE. THIS WILL SHUT DOWN THE SNOW FLURRIES BUT NOT KILL ALL THE CLOUDS UNTIL DURING THE DAY SUNDAY WITH SUNSHINE TO MIX IT OUT. COLD TONIGHT WITH TEMPS FALLING INTO THE 20S. TONIGHT AND SUNDAY NIGHT WILL END UP WITHIN 5 DEGREES OF THE RECORD DAILY LOWS. && .SHORT TERM /6 AM SUNDAY MORNING THROUGH TUESDAY/... 330 PM UPDATE... SUNDAY MORNING SOME LINGERING LAKE MOISTURE IN THE FORM OF LOWER CLOUDS BUT WITH WINDS SHIFTING TO NORTH AND NE NOTHING SHOULD BE FALLING OUT OF IT. SUNDAY SURFACE HIGH PRESSURE OVER THE AREA WITH THE WEAK UPPER LEVEL TROF MOVING EAST. WEAK WARM AIR ADVECTION ALOFT AND TEMPERATURES MODERATING AT THE SURFACE. WITH THE HIGH OVER THE AREA SUNDAY NIGHT LOW TEMPS WILL FALL BACK INTO THE 20S. THE HIGH PRESSURE MOVES TO NOVA SCOTIA MONDAY AND SLOWS. A RIDGE OF HIGH PRESSURE EXTENDS ALONG THE EAST COAST. AFTER A MOSTLY SUNNY SUNDAY AFTERNOON AN ONSHORE FLOW WILL BRING MOISTURE IN FROM THE SOUTHEAST SUNDAY NIGHT TO TUESDAY. SOME MODELS EVEN BRINGING SOME LIGHT QPF. HAVE A SLIGHT CHANCE OF LIGHT RAIN SHOWERS AND DRIZZLE MONDAY NIGHT AS A STORM MOVES NORTHEAST PARALLEL TO THE COAST BUT WELL OFFSHORE. THE COLD FRONT DUE WED IS CLOSE ENOUGH TO SHIFT THE WINDS TO SOUTH SCOURING OUT THE ATLANTIC MOISTURE TUE AFTN. && .LONG TERM /TUESDAY NIGHT THROUGH SATURDAY/... A FAIRLY QUITE PD WX-WISE FOR THE MED RNG. OVERALL PTRN WILL FEATURE THE DVLPMNT OF A FAIRLY BROAD TROF OVER THE CNTRL U.S.. A S/WV MOVING THRU THIS FEATURE AND IT`S ASSCD FNTL SYSTEM WILL APRCH LATER TUE NGT AND CROSS THE FCST AREA ON WED WITH A BATCH OF RAIN OR SHOWERS. AFTER THIS TIME...MDLS SUGGEST ONLY WEAK UPR LVL IMPULSES WITH SFC RIDGING OCCURING...SO DRY WX WILL PREVAIL. NXT FNTL SYSTEM MAY GET INTO THE RGN BY NXT WEEKEND. SO AFTER WED`S RAIN...PARTLY TO MOSTLY SUNNY SKIES AND TEMPS GETTING BACK TO SEASONAL NORMS. HPC GUIDANCE LOOKED GOOD AND WAS UTILZED WITH SOME MINOR TWEEKS TO CLD GRIDS. && .AVIATION /20Z SATURDAY THROUGH THURSDAY/... VFR WILL PREVAIL THRU 18Z SUNDAY. SCT -SHRA ACRS CNTRL NY THIS AFTN ASSCD WITH AN UPR LVL S/WV AND WEAK SFC TROF...BUT LTL IN THE WAY OF RESTRICTIONS. XPCT THIS ACTIVITY TO WANE LATER THIS AFTN AND EVNG. MAIN FCST CHALLENGE WAS DETERMINING THE POTNL FOR A PD OF MVFR CIGS ACRS PORTIONS OF CNTRL NY LATER TNGT DUE TO COLD NW FLOW ACRS THE LAKES. RUC PROFILES BCM VERY MOIST AT LOW LVLS TNGT...IN CONTRAST TO OTHER MDLS INDICATING MUCH LESS SATURATION OF LOWER LVLS. GIVEN THE STREAMERS ACRS THE GTLAKES TDA...BELIEVE LAKE CLDS ARE LIKELY LATER TNGT SPCLY SYR/ITH AND PSBLY BGM...BUT FOR NOW JUST INDICATED A BKN035 DECK. ANY CLDS TMRW MRNG WILL DSPT RAPIDLY LEAVING SUNNY SKIES. WINDS THIS AFTN WRLY 15-20 G25-30...DIMINISHING THIS EVNG...THEN N TO NW WINDS 5-10 KTS SUN MRNG. .OUTLOOK... SUN NGT THROUGH MON...VFR UNDER HIGH PRESSURE. MON NGT...PSBL MVFR FAR SRN NY AND NE PA DUE TO SE FLOW/MARINE LAYER. TUE/TUE NGT...VFR. WED/WED NGT...MVFR IN SHRA. THU...VFR. && .BGM WATCHES/WARNINGS/ADVISORIES... PA...NONE. NY...NONE. && $$ SYNOPSIS...DJN/TAC NEAR TERM...TAC SHORT TERM...TAC LONG TERM... AVIATION...
AREA FORECAST DISCUSSION
NWS BINGHAMTON NY
153 PM EDT SAT APR 20 2013 .SYNOPSIS... A BRISK AND COLD NORTHWEST FLOW OF AIR WILL BRING SCATTERED RAIN SHOWERS, MIXED WITH A FEW SNOW SHOWERS AT TIMES TO THE REGION TODAY. HIGH PRESSURE WILL THEN BUILD IN ACROSS THE REGION LATE TONIGHT WITH VERY CHILLY TEMPERATURES FOR THIS TIME OF YEAR. THIS HIGH PRESSURE SYSTEM WILL LINGER OVER THE NORTHEAST UNITED STATES THROUGH EARLY NEXT WEEK, WITH FAIR SKIES AND SLOWLY MODERATING TEMPERATURES. && .NEAR TERM /THROUGH TONIGHT/... 1030 AM UPDATE... MINOR CHANGES. THE GRIDS ARE CLOSE TO ACTUAL. FOR THIS AFTERNOON AND EVENING THE LOW LEVEL FLOW SHIFTS TO NW WITH VERY COLD AIR ALOFT FOR LATE APRIL. UPPED CLOUDS, QPF, AND POPS MOSTLY IN CENTRAL NY. LITTLE TO WORRY ABOUT TODAY AND TONIGHT. ONE SHORT WAVE AND A NE TO SW LINE OF SHOWERS MOVING THROUGH NOW WITH MIXED PRECIP. LITTLE IF ANY SNOW ACCUMULATION. ANOTHER SHORT WAVE AROUND 00Z WILL HELP THE LAKE ENHANCEMENT. PREVIOUS DISCUSSION... RADAR STILL SHOWS LINGERING SHOWERS IN NE PA AND THE CATSKILLS IN ASSCTN WITH ANOTHER SHORT WAVE LIFTG NORTHEASTARD THRU THE ERN OH VLLY TWD THE LOWER LAKES. THIS WAVE WAS APPARENT ON THE WV IMAGERY AND ALSO CAPTURED WELL IN THE NAM12 DYNAMIC TROPAPAUSE FIELDS. THE 1.5 PV UNIT SFC DROPS DOWN TO ALMOST 600 MB IN NC OH ATTM. THIS WAVE WILL CONT NORTHEAST EARLY THIS MORNING AND THIS LAST LINGERING BATCH OF RAINS WILL ADVECT N AND E AND FINALLY EXIT NE PA AND THE CATSKILLS BY ARND 10Z OR SO AS PER THE LATEST HRRR MODEL WHICH SEEMS TO HAVE THE BEST HANDL ON THE PRECIP. HV POPS IN THE SERN PART OF THE FORECAST AREA UNTIL 9-10Z. ONCE THIS SHRT WAVE RAPIDLY LIFTS NORTHEAST LATER THIS MORNING INTO SERN CANADA A STRG COLD AIR ADVECTION PATTERN SETS UP ACRS ALL OF CENTRAL NY AND NORTHEAST PA. H85 TEMPS FALL TO BETWEEN -8 AND -12C BY THIS EVE ACROSS MUCH OF CWA AS PER 00Z NAM AND GFS. THIS IS REALLY CHILLY FOR THIS TIME OF YEAR. MODEL SOUNDINGS FOR ALL AVBL MODELS SHOW PATCHY CLOUDS THIS MORNING RAPIDLY FILLING IN TO A BKN-OVC SC/CU LAYER WITH INSOLATION GIVE THE CHILLY AIR ALOFT AND A SHARP INVERSION ARND 800 TO 750 MB. SOUNDINGS SHOW SOME SHALLOW CAPE UNDER THIS INVERSION SUGGESTING SHRA AND EVEN A MIX OF RAIN AND SNOW DEVELOPING. NO SNOW ACCUMULATIONS EXPECTED BUT IT WILL BE COLD ENUF AT TIMES FOR SNOW TO BE OBSERVED. SO WILL HAVE SCT SHRA AND SN ESP THIS MORNING IN GRIDS. BY AFTERNOON BNDRY LAYER DRIES OUT SOME AS MUCH LOWER SFC DEWPOINTS START WORKING IN COUPLED WITH DRIER AIR ALOFT WHICH WILL MIX DOWN FROM ABV THE INVERSION. I SEE CLDS EVENTUALLY SCATTERING OUT LATE IN THE DAY INTO THE EVE WITH MINIMAL CHC/S FOR PRECIP BY THEN. HIGHEST POPS WILL BE LATE MORNING TO MID AFTERNOON...THEN WANING. PRESSURE GRADIENT WILL BECOME FAIRLY STRONG TODAY AND WITH INSTABILITY PRESENT IN THE LL/S THERE IS SOME GUST POTENTIAL. LOOKS LIKE THERE WILL BE A CHANCE OF WINDS TO COME CLOSE TO ADVY AGAIN...ESP IN C NY. 12 HR PRESSURE RISES WERE ARND 10-12 MB/6 HR WHICH IS MARGINAL FOR ADVY BASED ON LOCAL STUDY. SO THINK WE WILL SEE A FEW GUSTS APPROACH 40 MPH AND NOT ISSUE AN ADVY AT THIS TIME. && .SHORT TERM /SUNDAY THROUGH TUESDAY/... FOR TONIGHT...LARGE COLD SURFACE HIGH RAPIDLY BUILDS IN ACRS THE EASTERN LAKES BY 12Z SUN. THIS WILL LEAD TO MAINLY CLEAR SKIES AND WITH COLD TEMPERATURES PRESENT FROM THE STRG COLD AIR ADVECTION TODAY...TONIGHT WILL BE A VERY COLD NIGHT FOR LATE APRIL. NAM MET GUIDC HAS BGM DROPPING TO 20F WITH 6-7 KTS OF WIND....THIS IS ONE DEGREE BELOW THE RECORD LOW FOR THE DATE! IN FACT THE MET GUIDC HAS MIN/S TONIGHT ARND 20F ALL SITES WHICH IS CLOSE TO RECORD LOWS. ALL SITES WILL MAINTAIN SOME WIND TOO WHICH IS INDICATIVE OF HOW COLD THIS AIR MASS IS. THE GFS MOS IS A FEW DEGREES WARMER AND AGAIN ALSO KEEPS THE WINDS UP WHICH WILL LIMIT THE NET RADITIONAL COOLING POTENTIAL IN THE DEEPER VALLEYS. WILL GO WITH A BLEND OF THE MET AND MOS FOR MINS TONIGHT. GROWING SEASON HAS NOT BEGUN YET FOR ANY OF OUR FORECAST AREA SO NO HEADLINES FOR THE PROLONGED FREEZE CONDITIONS. THIS LARGE HIGH PRESSURE SYSTEM SLOWLY DRIFTS EASTWARD COVERING NEW ENGLAND BY 00Z MON. THUS SUNDAY WILL START OFF VERY COLD BUT THERE WILL BE AMPLE SUNSHINE. 850 MB TEMPS REMAIN BELOW -5C MOST OF THE DAY INDICATIVE OF ANOTHER CHILLY DAY...BUT THE WIND WILL BE MUCH LIGHTER. WITH SUCH DRY AIR IN THE LOW-LEVELS THERE WILL BE LITTLE IF ANY CU FORMATION SUNDAY. SO I EXPECT SUNNY SKIES. FOR SUNDAY NIGHT AND MONDAY THIS LARGE HIGH WILL CONT TO SLIDE FARTHER EAST WELL OFF THE MARITIMES WITH A SIGNIFICANT COOL AIR DAMMING SIGNATURE SETTING UP E OF THE APPLCNS. DWPTS WILL REMAIN IN THE 20S AND LOW 30S FOR MOST OF THIS TIME PERIOD WITH LITTLE CLD CVR EXPECTED. H85 TEMPS WILL REMAIN SLIGHTLY BELOW 0C CONTINUING BELOW NORMAL TEMPERATURES. FOR MONDAY NIGHT...ONCE AGAIN COOL AIR DAMMING SIGNATURE WILL REMAIN IN PLACE AS LOW PRESSURE DEVELOPS SOUTH OF THE ABOVE MENTIONED LARGE HIGH PRESSURE SYSTEM OFF THE MARITIMES AND TRACKS SLOWLY NORTHEAST WELL OFF THE EAST COAST. HENCE PA AND NY WILL REMAIN IN BETWEEN THIS STORM AND THE NEXT SYSTEM MOVING THRU THE GREAT LAKES WHICH REACHES NRN LWR MI BY 12Z TUE. THUS I SEE A CONTINUATION OF FAIR AND DRY WEATHER MON NGT AS WELL. && .LONG TERM /TUESDAY NIGHT THROUGH FRIDAY/... A FAIRLY QUITE PD WX-WISE FOR THE MED RNG. OVERALL PTRN WILL FEATURE THE DVLPMNT OF A FAIRLY BROAD TROF OVER THE CNTRL U.S.. A S/WV MOVING THRU THIS FEATURE AND IT`S ASSCD FNTL SYSTEM WILL APRCH LATER TUE NGT AND CROSS THE FCST AREA ON WED WITH A BATCH OF RAIN OR SHOWERS. AFTER THIS TIME...MDLS SUGGEST ONLY WEAK UPR LVL IMPULSES WITH SFC RIDGING OCCURING...SO DRY WX WILL PREVAIL. NXT FNTL SYSTEM MAY GET INTO THE RGN BY NXT WEEKEND. SO AFTER WED`S RAIN...PARTLY TO MOSTLY SUNNY SKIES AND TEMPS GETTING BACK TO SEASONAL NORMS. HPC GUIDANCE LOOKED GOOD AND WAS UTILZED WITH SOME MINOR TWEEKS TO CLD GRIDS. && .AVIATION /18Z SATURDAY THROUGH THURSDAY/... VFR WILL PREVAIL THRU 18Z SUNDAY. SCT -SHRA ACRS CNTRL NY THIS AFTN ASSCD WITH AN UPR LVL S/WV AND WEAK SFC TROF...BUT LTL IN THE WAY OF RESTRICTIONS. XPCT THIS ACTIVITY TO WANE LATER THIS AFTN AND EVNG. MAIN FCST CHALLENGE WAS DETERMINING THE POTNL FOR A PD OF MVFR CIGS ACRS PORTIONS OF CNTRL NY LATER TNGT DUE TO COLD NW FLOW ACRS THE LAKES. RUC PROFILES BCM VERY MOIST AT LOW LVLS TNGT...IN CONTRAST TO OTHER MDLS INDICATING MUCH LESS SATURATION OF LOWER LVLS. GIVEN THE STREAMERS ACRS THE GTLAKES TDA...BELIEVE LAKE CLDS ARE LIKELY LATER TNGT SPCLY SYR/ITH AND PSBLY BGM...BUT FOR NOW JUST INDICATED A BKN035 DECK. ANY CLDS TMRW MRNG WILL DSPT RAPIDLY LEAVING SUNNY SKIES. WINDS THIS AFTN WRLY 15-20 G25-30...DIMINISHING THIS EVNG...THEN N TO NW WINDS 5-10 KTS SUN MRNG. .OUTLOOK... SUN NGT THROUGH MON...VFR UNDER HIGH PRESSURE. MON NGT...PSBL MVFR FAR SRN NY AND NE PA DUE TO SE FLOW/MARINE LAYER. TUE/TUE NGT...VFR. WED/WED NGT...MVFR IN SHRA. THU...VFR. && .BGM WATCHES/WARNINGS/ADVISORIES... PA...NONE. NY...NONE. && $$ SYNOPSIS...DJN NEAR TERM...DJN/TAC SHORT TERM...MDP