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