Area Forecast Discussion
Issued by NWS Jackson, KY

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FXUS63 KJKL 251215 AAA
AFDJKL

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE JACKSON KY
715 AM EST WED NOV 25 2009

.SHORT TERM.../TODAY THROUGH FRIDAY/

07Z SFC ANALYSIS SHOWS A FAIRLY DEEP LOW PRESSURE CENTER LOCATED OVER
CHI WITH A COLD FRONT FROM THIS CROSSING CENTRAL KENTUCKY. AS IT DOES
SO...IT IS KICKING UP AN AREA OF WIDELY SCATTERED LIGHT SHOWERS AND
SPRINKLES OVER EAST KENTUCKY. IN ADDITION...THE WINDS ARE PICKING UP
FROM THE SOUTH AS THIS BOUNDARY APPROACHES...WITH SOUTHWEST WINDS
FOUND BEHIND IT. EARLIER CLEAR PATCHES IN THE EAST HAVE FILLED BACK
IN WITH THE APPROACH OF THE FRONT AND THIS...COMBINED WITH THE
INCREASING WINDS...WILL HELP TO MIX OUT THE COOLER EASTERN VALLEYS
WHERE TEMPERATURES HAD FALLEN INTO THE LOWER 40S EARLIER IN THE
NIGHT. ELSEWHERE...TEMPERATURES ARE GENERALLY IN THE LOWER 50S WITH
DEWPOINTS THROUGH THE AREA IN THE LOWER TO MIDDLE 40S.

THE MODELS CONTINUE TO HAVE MINOR DIFFERENCES ALOFT WITH THEIR
HANDLING OF THE DOUBLE BARRELED TROUGH THAT WILL AFFECT THE REGION
THROUGH THE HOLIDAY WEEKEND. THE LEAD SHORTWAVE TROUGH WHIPS THROUGH
THE OHIO VALLEY TODAY...SIMILARLY IN ALL MODELS. IT IS THE
SECONDARY...AND SOON TO BECOME MAIN...TROUGH THAT WILL DRIVE THE
FORECAST IN THE SHORT TERM. THIS LATTER TROUGH...DROPPING OUT OF THE
NORTHERN PLAINS TODAY...WILL WRAP UP QUICKLY INTO A POTENT CLOSED LOW
BY EVENING. AS THIS LOW THEN BARRELS THROUGH THE MIDWEST AND INTO THE
OHIO VALLEY...IT WILL BECOME THE ANCHOR OF A FULL LATITUDE TROUGH.
THE ENERGY STREAM FROM THIS LARGE TROUGH WILL SWEEP THROUGH KENTUCKY
THURSDAY EVENING. FOLLOWING THIS...THE LARGE CLOSED LOW CONSOLIDATES
OVER THE MID ATLANTIC STATES AND OFFSHORE BY FRIDAY. THE NEW ECMWF
SOLUTION FALLS IN THE MIDDLE OF THE MODEL SPREAD AND SEEMS A
REASONABLE COMPROMISE BALANCING THE QUICKER AND FURTHER NORTH TRACK
OF THE TROUGH FROM THE GFS ON THURSDAY AND THEN THE FURTHER SOUTHEAST
PLACEMENT OF THE NAM/S LOW CENTER AT 12Z FRIDAY. ACCORDINGLY...FOR
WEATHER SPECIFICS...FOLLOWED THE ECMWF FOR THE SYNOPTIC PATTERN
MAKING CLIMATOLOGICALLY BASED ADJUSTMENTS TO ACCOUNT FOR ITS POORER
RESOLUTION...SPECIFICALLY WHEN IT COMES TO UPSLOPE DETAILS ON
THURSDAY NIGHT AND FRIDAY.

SENSIBLE WEATHER WILL FEATURE THE FIRST COLD FRONT MOVING EAST OF THE
AREA THIS MORNING TAKING ITS PCPN CHANCES ALONG WITH IT. THE SFC LOW
THAT SPAWNED THE FRONT WILL STALL OVER THE GREAT LAKES IN RESPONSE
TO THE DEEPENING UPPER LEVEL SUPPORT TO THE SOUTHWEST TODAY.
MEANWHILE...LOW PRESSURE WILL BE CONSOLIDATING OFF THE SOUTHEAST
COAST. THIS COASTAL SYSTEM WILL THEN DEEPEN TONIGHT...BECOMING THE
MAIN LOW DURING THE DAY THURSDAY. AT THE SAME TIME CLOSER TO HOME...
THE UPPER LEVEL ENERGY WILL CRASH THROUGH THE OHIO VALLEY SPAWNING
SCATTERED SHOWERS OVER THE AREA. BY FRIDAY MORNING...A MODERATE
NOR`EASTER WILL BE UNDERWAY OFF THE NEW ENGLAND COAST. THE
DEVELOPMENT OF THIS LARGE CYCLONE WILL PULL COLDER AIR INTO KENTUCKY
COOLING THE COLUMN AND LIKELY ALLOWING SNOW TO MIX WITH ANY RAIN
SHOWERS INTO THURSDAY NIGHT AND FRIDAY MORNING. THE WHOLE SYSTEM
WILL BE FAIRLY PROGRESSIVE...THOUGH...AND AS A RESULT THE PCPN WILL
PULL OUT OF THE CWA BY FRIDAY EVENING. BUT THIS WILL PROBABLY NOT
HAPPEN BEFORE THE HIGHEST EASTERN RIDGES NEAR VIRGINIA MANAGE TO
PICK UP A DUSTING TO AN INCH OF ACCUMULATION. ELSEWHERE...GROUND
TEMPERATURES WILL BE TOO WARM FOR ANY ACCUMULATIONS...THOUGH THE
BRIDGES AND OVERPASSES COULD BECOME SLICK THURSDAY NIGHT INTO FRIDAY
MORNING. WILL ADDRESS THIS CONCERN IN THE HWO TO BE ISSUED LATER THIS
MORNING.

UNDERCUT MOS FOR HIGHS AGAIN TODAY IN THE FACE OF MILD CAA. LATER
ON...PREFERRED THE COOLER MAV NUMBERS FOR LOWS THURSDAY NIGHT AND
EVEN UNDERCUT THESE FOR HIGH TEMPERATURES IN THE FAR EAST ON FRIDAY.
AS FOR POPS...ENDED UP CLOSEST TO THE MET NUMBERS THROUGH THE
PERIOD...BUT WENT HIGHER ON FRIDAY IN THE EAST.

.LONG TERM.../FRIDAY NIGHT THROUGH TUESDAY/

FORECAST MODELS CONTINUE TO ADVERTISE A QUICK RETURN TO A LOW
AMPLITUDE UPPER LEVEL RIDGE FOR THE WEEKEND OVER OUR AREA AS ENERGY
DIVES DOWN INTO A DEVELOPING TROUGH OVER THE INTERMOUNTAIN WEST.
BUILDING SURFACE HIGH PRESSURE AND EVEN SOME DEVELOPING WARM
ADVECTION FRIDAY NIGHT SHOULD END ANY PRECIP BEFORE NIGHTFALL AND
THEN RESULT IN A QUICK SCOURING OUT OF ANY RESIDUAL CLOUD COVER
OVERNIGHT. FAIR TO PARTLY CLOUDY SKIES AND A BIT OF A WARM UP IS
THEN ANTICIPATED SATURDAY INTO SUNDAY MORNING... ALTHOUGH FORECAST
SOUNDINGS INDICATE A SUPPRESSED MIXED LAYER BOTH SATURDAY AND SUNDAY
AND THUS WE KEPT MUCH BELOW THE 25/00Z GFSX GUIDANCE NUMBERS EACH
DAY.

MOISTURE WILL BE ON THE INCREASE BY SUNDAY AFTERNOON AS SOUTHWEST
FLOW ALOFT DEVELOPS IN ADVANCE OF THE ELONGATED TROUGH TO OUR WEST.
THIS SHOULD RESULT IN INCREASING CLOUDS AND A SLIGHT THREAT FOR A
FEW SHOWERS LATE IN THE DAY OVER OUR WESTERN COUNTIES. RAIN CHANCES
THEN INCREASE INTO SUNDAY NIGHT.

UNCERTAINTY INCREASES QUITE A BIT MONDAY AND TUESDAY. THE UPPER
LEVEL TROUGH TO OUR WEST IS PROGGED TO SLOWLY PROGRESS EASTWARD
DURING THIS PERIOD BUT THERE REMAIN BIG MODEL DIFFERENCES IN HOW IT
DOES SO. WHILE THE HIGHLY AMPLIFIED AND WOUND UP SOLUTION OFFERED BY
THE 25/00Z GFS IS NICE TO LOOK AT AND ENTIRELY PLAUSIBLE... WE WILL
CONTINUE TO FAVOR THE MORE CONSISTENT AND LESS AMPLIFIED 25/00Z
ECMWF FOR NOW AS IT HAS MUCH MORE ENSEMBLE SUPPORT. THUS EXPECT A
PROLONGED THREAT FOR RAIN... WITH THE BEST CHANCE ARRIVING MONDAY
AND MONDAY NIGHT. KEPT DAYTIME HIGHS COOLER THAN THE 25/00Z GFSX
GUIDANCE NUMBERS MONDAY AND TUESDAY AS WELL.

&&

.AVIATION.../12Z TO 12Z/...UPDATED

MVFR AND LOW END VFR CIGS ASSOCIATED WITH THE PASSING COLD FRONT
COVER MOST OF EAST KENTUCKY...BUT IS ERODING FROM THE WEST. THE
CLOUDS SHOULD BREAK UP TOWARD MID MORNING...FOLLOWING FROPA...LEAVING
BEHIND A SCATTERED BATCH OF CLOUDS AROUND 2.5K FEET...BUT PROBABLY
NOT ENOUGH TO FORM A CIG UNTIL LATER IN THE EVENING WHEN ANOTHER
MOSTLY DRY FRONT WILL APPROACH. SOUTHWEST WINDS WILL RUN AT NEAR 10
KTS TODAY WITH GUSTS TO BETWEEN 15 AND 20 KTS BEFORE SETTLING DOWN
SOMEWHAT THIS EVENING AND BECOMING MORE WESTERLY.

&&

.JKL WATCHES/WARNINGS/ADVISORIES...NONE.

&&

$$

SHORT TERM...GREIF
LONG TERM....ABE
AVIATION...GREIF





  • National Weather Service
  • Jackson, KY Weather Forecast Office
  • 1329 Airport Road
  • Jackson, KY 41339
  • 606-666-8000
  • Page Author: JKL Webmaster
  • Web Master's E-mail: w-jkl.webmaster@noaa.gov
  • Page last modified: Nov 10th, 2009 17:45 UTC
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