Area Forecast Discussion
Issued by NWS Paducah, KY

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000
FXUS63 KPAH 141819
AFDPAH

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE PADUCAH KY
119 PM CDT TUE APR 14 2015

.SHORT TERM...(THIS EVENING THROUGH THURSDAY NIGHT)
ISSUED AT 105 PM CDT TUE APR 14 2015

A SURFACE LOW CONTINUES TO MOVE AWAY FROM THE PAH CWA AS IT
DEPARTS TN FOR THE MID ATLANTIC THIS PM. EVENTUALLY...THAT WILL
ALLOW THE PRESSURE GRADIENT BETWEEN IT AND THE SURFACE HIGH TO THE
NORTH TO RELAX AND THE WINDS TO DIMINISH SOME FROM THEIR LATE
MORNING TO MIDDAY GUSTINESS. IT WILL ALSO ALLOW THE HIGH TO DRAW
SOME DRIER AIR DOWN THE COLUMN...AND GIVES US A RELATIVE LULL IN
POPS UNTIL THE NEXT ROUND.

A TELECONNECTED WEAK UPPER RIDGE WILL WILL CONTRIBUT TO THIS
RELATIVE SHORT TERM DRY PERIOD AS IT MOVES OVERHEAD TONIGHT...AND AS
THE SURFACE HIGH RETREATS FURTHER TO THE NORTH OVER THE GREAT
LAKES. SO AFTER A MAINLY DRY NIGHT TONIGHT...POPS WILL REENTER THE
FORECAST FROM THE SOUTHWEST LATE TONIGHT-INTO TMRW...AS THE MEAN
UPPER LEVEL FLOW BACKS IN RESPONSE TO THE 100-120 KT JET CORE
DIGGING A LONG WAVE TROF OVER THE MID ROCKIES REGION. NUMEROUS SRN
STREAM SHORT WAVES INTERACT AND SHIFT ABUNDANT MOISTURE THAT IS IN
PLACE TO OUR SOUTH...NORTHWARD AND EASTWARD INTO OUR AREA. THE
MODELS PICK UP ON ONE SUCH (WEAK) WAVE IN PARTICULAR LIFTING OUT
OF THIS FLOW THAT INDUCES A RELATIVE SPIKE IN POPS WED EVENING AND
TRANSLATES ACROSS THE AREA THRU THURSDAY MORNING. POPS
DIMINISH/TAPER THEREAFTER...BUT DO NOT DISAPPEAR ALTOGETHER...AS
THAT WAVE DEPARTS THURSDAY EVENING. INSTABILITY PARAMETERS SUGGEST
INCLUSION OF THUNDER BEYOND ABOUT 18Z WEDNESDAY IS WARRANTED...ALTHOUGH
ISOLD MENTIONABLES IS PROBABLY ALL THAT IS NECESSARY AT THIS
WRITING GIVEN THE SUPPORTING MAINLY ELEVATED PARAMETERS ARE ONLY
MARGINAL.

.LONG TERM...(THURSDAY NIGHT THROUGH TUESDAY)
ISSUED AT 340 AM CDT TUE APR 14 2015

THE 00Z GFS...ECMWF...AND GEM ARE IN AGREEMENT IN TAKING THE MID
/UPPER-LEVEL TROUGH...CURRENTLY COMING ONSHORE THE PACIFIC
NORTHWEST...SOUTHEAST INTO THE SOUTHERN ROCKIES BY 00Z FRIDAY. THE
MODELS ARE ACTUALLY IN DECENT AGREEMENT IN TIMING IMPULSES IN THE
NORTHERN STREAM ALONG THE CANADIAN BORDER THROUGH SATURDAY...BUT
DIFFER IN HOW THE SOUTHERN ROCKIES SYSTEM INTERACTS WITH THE
NORTHERN STREAM FLOW.

THE GFS APPEARS TO BE THE OUTLIER IN KEEPING ITS SOUTHERN ROCKIES
SYSTEM SEPARATED FROM THE NORTHERN STREAM FLOW LONGER...AND PUSHING
IT FARTHER EAST FASTER THAN THE ECMWF AND GEM. THIS RESULTS IN SOME
TIMING DIFFERENCES IN BETTER POPS ACROSS OUR REGION. ALL 3
OPERATIONAL RUNS DO EMPHASIZE SUNDAY FOR AT LEAST A GOOD CHANCE
POP...AS THE REMNANTS OF THE SOUTHERN ROCKIES SYSTEM MOVE OVERHEAD.
THE ECMWF AND GEM WOULD WARRANT ONLY LOW POPS OUTSIDE OF SUNDAY AND
SUNDAY NIGHT.

WILL HAVE BETTER CHANCES IN THE FRIDAY THROUGH SATURDAY PERIOD JUST
IN CASE THE GFS HAS A CLUE. OTHERWISE...PUSHED THE FORECAST TOWARD
THE DRIER ECMWF/GEM FORECAST. SUSPECT THAT MONDAY WILL BE DRY...AND
NEXT TUESDAY SHOULD DEFINITELY BE SO...AS SURFACE HIGH PRESSURE
FINALLY BUILDS ACROSS THE REGION.

THE GFS HAS EITHER ELEVATED OR SURFACE-BASED INSTABILITY AVAILABLE
THROUGH NEXT WEEKEND...SO WILL MENTION A CHANCE OF THUNDERSTORMS
THROUGHOUT THE PERIOD. WITH GENERALLY WEAK SOUTHWEST FLOW ALOFT
THROUGH THE PERIOD...SEVERE WEATHER SEEMS UNLIKELY AT THIS TIME.
LOCALLY HEAVY RAINFALL WOULD BE THE PRIMARY CONCERN LATE THIS WEEK
AND NEXT WEEKEND.

THE GFS AND ECMWF ARE IN DECENT AGREEMENT IN DEVELOPING A
SIGNIFICANT UPPER LOW OVER ONTARIO...WITH CYCLONIC FLOW OVER MOST OF
THE COUNTRY EAST OF THE ROCKIES. THIS SHOULD RESULT IN COOLER AND
DRIER CONDITIONS ACROSS THE REGION FOR THE FIRST HALF OF NEXT
WEEK...AND POSSIBLY LONGER.

TEMPERATURES WILL GENERALLY BE MILD THROUGH THE WEEKEND...BUT WITH
PLENTY OF CLOUD COVER AND PRECIPITATION CHANCES...IT IS NOT LIKELY
TO GET OUT OF THE 70S. A COOL DOWN IS LIKELY EARLY NEXT WEEK.

&&

.AVIATION...
ISSUED AT 105 PM CDT TUE APR 14 2015

HIGH PRESSURE TO THE NORTH IS DRAWING DRIER AIR DOWN THE COLUMN
AND RESULTING IN MVFR CIGS YIELDING TO VFR CIGS THIS PM. THIS
TREND WILL CONTINUE THRU THE EVENING AND INTO THE OVERNIGHT HOURS
AS THE HIGH STRENGTHENS ITS GRIP ON OUR WEATHER...AS THE
DEPARTING SURFACE LOW RESPONSIBLE FOR THE RAIN EVENT MAKES ITS
WAY TOWARD THE MID ATLANTIC. ALSO AS THIS OCCURS...NE WINDS BEGIN
TO RELAX/DIMINISH INTO THE EVENING HOURS AS THEY LIKEWISE LOSE
THEIR GUSTINESS UPON THE PRESSURE GRADIENT BETWEEN THE TWO SYSTEMS
LOOSENS. LATE IN THE FORECAST PERIOD...WE SOUP UP AGAIN WITH
LOWERING CIGS AND AN INCOMING CHANCE OF RAIN FROM THE SOUTH/WEST.

&&

.PAH WATCHES/WARNINGS/ADVISORIES...
IL...NONE.
MO...NONE.
IN...NONE.
KY...NONE.
&&

$$



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