FXUS63 KJKL 220923
AFDJKL
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JACKSON KY
423 AM EST TUE DEC 22 2009
.SHORT TERM.../THE REST OF TODAY/...UPDATED
WARM AIR ADVECTING ACROSS THE SNOW FIELDS HAS CREATED PATCHY FOG. DUE
TO THE SUB FREEZING TEMPERATURES... THIS FOG HAS THE POTENTIAL TO
FREEZE ON EXPOSED SURFACES. THEREFORE WE WILL ISSUE A FREEZING FOG
ADVISORY VALID UNTIL 10 AM.
THE PREVIOUS SHORT TERM FORECAST DISCUSSION FOLLOWS...
/TODAY THROUGH THURSDAY/
QUIET WEATHER FOR THE FIRST HALF OF THE SHORT TERM FCST. TEMPS ON THE
RISE WITH NEAR 50 SOUTH AND MID 30S NORTH AS THE SOUTHERLY WIND BEGIN
TO DRAW WARMER AIR NORTH. THE NORTHERN HALF OF THE AREA WILL SPEND
MOST OF THE ENERGY FROM THE WARM AIR ADVECTION IN MELTING THE SNOW
PACK. MOST SNOW SHOULD BE GONE BY WED WITH EVEN THE NRN HALF OF THE
CWFA CLIMBING INTO THE 40S. BY THU THE ENTIRE CWFA SHOULD BE FLIRTING
WITH THE LOWER 50S. THE WAA WITH ALSO ADVECT ADDITIONAL MOISTURE TO
COMBINE WITH THE MOISTURE FROM THE MELTING SNOW. BY WED AFTERNOON THE
DEVELOPING LOW IN THE CNTRL PLAINS WILL BRING SHRA TO WRN KY AS WINDS
INCREASE FROM THE S AND SE ACROSS THE AREA. ALTHOUGH THE 00Z GFS DOES
NOT BRING IN PCPN TO THE AREA UNTIL THU THE ECWMF HAS -SHRA STARTING
AS EARLY AS WED NITE FOR OUR SWRN COUNTIES. ALL MODELS HAVE THE PCPN
INTO THE CWFA BY THU AND HAVE THE SWRN COUNTIES IN CAT POPS BY LATE
THU. THE SPEED OF THE SYSTEM SHOULD LIMIT QPF AND WITH THE WARM TEMPS
THE PREVIOUS COUPLE OF DAYS... DO NOT EXPECT MUCH LINGERING SNOW SO
RUNOFF WILL BE LIMITED. AS A RESULT...EVEN WITH THE MELTING SNOW
FROM WEDNESDAY AND THURSDAY...EXPECT THE RIVERS TO BE ABLE TO CONTAIN
THE MELT OFF AND RUN OFF FROM ADDITIONAL RAINFALL AS IT IS SPREAD
OVER 3 DAYS. NO SNOW FCST FOR THE CHRISTMAS HOLIDAY IN ERN KY. THURSDAY
WILL ALSO BE NOTED FOR ITS GUSTY WINDS AS A TIGHT PRESSURE GRADIENT
WILL PASS OVER THE CWA DURING THE AFTERNOON AND EVENING HOURS...BUT
AT THIS POINT IT LOOKS TO BE A WEAKER SET UP THAN THE HIGH WINDS WE
SAW FROM A SIMILAR STRONG LOW PASSING TO OUR WEST A COUPLE OF WEEKS
AGO.
.LONG TERM.../THURSDAY NIGHT THROUGH MONDAY/
A COMPLEX UPPER LEVER PATTERN KICKS OFF THE LONG TERM PORTION OF THE
FORECAST AS TWO TROUGHS WILL BE DROPPING THROUGH THE ROCKIES WHILE
RIDGING IS SQUEEZED AND AMPLIFIED THROUGH THE OHIO VALLEY. THE
SOUTHERN MOST TROUGH TO OUR WEST IS EVENED OUT BY THURSDAY NIGHT
AS THE TROUGH SPIRALS AND DEEPENS INTO A DEEP CLOSED LOW NEAR
MKC...THOUGH THE GFS HOLDS BACK MORE ENERGY AND KEEPS IT FOR THE
SECOND TROUGH FURTHER TO THE WEST...SINKING IT THROUGH THE ROCKIES.
MEANWHILE IN THE EAST...STRONG RIDGING WILL MOVE EAST TO THE OTHER
SIDE OF THE APPALACHIANS. AT THIS POINT...ANY SEPARATION BETWEEN THE
TROUGHS BLURS AS ONE BIG CLOSED LOW ROLLS NORTH THROUGH THE MIDDLE
AND UPPER MISSISSIPPI VALLEY ON FRIDAY...ONLY SLOWLY APPROACHING
KENTUCKY. BY SATURDAY MORNING THE GFS RETURNS TO ITS PROGRESSIVE WAYS
AND MOVES THE LOW INTO THE GREAT LAKES WHILE THE ECMWF LINGERS ITS
LOW BEHIND THROUGH THE WEEKEND. THESE DIFFERENCES FURTHER MAGNIFY ON
SUNDAY WITH THE DEEP LOW FROM THE ECMWF STILL JUST ENTERING THE GREAT
LAKES WHILE THE GFS HAS ALREADY SPUN ITS OWN NORTH INTO CENTRAL
CANADA. HOWEVER...LINGERING LOWER HEIGHTS THROUGH THE OHIO VALLEY IN
THE GFS WILL MITIGATE SOME OF THE DISCREPANCIES FOR SENSIBLE WEATHER.
MONDAY WILL FEATURE FLAT RIDGING BUILDING ACROSS THE PLAINS AND INTO
THE TENNESSEE VALLEY FROM THE GFS WHILE THE ECMWF IS STILL SLOWLY
CLEARING OUT THE UPPER LOW AND TROUGH OVER THE REGION. HAVE FOLLOWED
THE ECMWF MOST CLOSELY THROUGH FRIDAY BEFORE SPLITTINGS THE
DIFFERENCE WITH THE GFS FOR THE WEEKEND INTO MONDAY...ALLOWING FOR A
BIT MORE PROGRESSIVE A SOLUTION LATER IN THE PERIOD.
SENSIBLE WEATHER WILL FEATURE A POTENT LOW DEVELOPING AND RACING
NORTH ON THURSDAY...JUST TO OUR WEST...BEFORE QUICKLY FILLING AND
SLOWLY DRIFTING THROUGH THE UPPER MIDWEST...GREAT LAKES...AND
NORTHERN OHIO VALLEY THROUGH THE HOLIDAY WEEKEND. THIS WILL FINALLY
CLEAR OUT ON MONDAY AND ALLOW HIGH PRESSURE TO RETURN TO THE AREA.
THE DEEPENING OF THE SYSTEM WILL HELP TO KEEP ITS FRONTAL STRUCTURE
FROM MOVING INTO EAST KENTUCKY UNTIL LATE THURSDAY...MINIMIZING THE
THREAT OF RAIN UNTIL THURSDAY NIGHT. ONCE THE FRONTS MOVE THROUGH
THAT NIGHT AND INTO FRIDAY...THEY SHOULD MOVE QUICKLY ENOUGH SO THAT
QPF WILL BE LIMITED ACROSS EAST KENTUCKY.
FOLLOWING A COUPLE OF DAYS OF 50 PLUS TEMPERATURES...COLDER AIR WILL
POUR BACK INTO THE STATE ON WEST WINDS FRIDAY AND SATURDAY. THIS
COLDER AIR WILL COMBINE WITH THE SOMEWHAT LIMITED WRAP AROUND
MOISTURE OF THE SYSTEM...AND VARIOUS UPPER LEVEL IMPULSE SPINNING
AROUND THE TROUGH...TO GENERATE A THREAT OF SNOW SHOWERS THROUGH THE
WEEKEND AND INTO MONDAY. THROUGHOUT THE WAKE OF THE SYSTEM/S COLD
FRONT THE WINDS WILL NEVER QUITE SWITCH AROUND TO A FAVORABLE
POSITION FOR UPSLOPE FLOW SO HAVE MINIMIZED THE ENHANCEMENT OVER OUR
EASTERN RIDGES LETTING THE BULK OF THE SNOW SHOWERS SLOWLY FILTER IN
FROM THE NORTHWEST AS THE STACKED SYSTEM FURTHER OPENS UP AND DRIFTS
BY TO THE NORTH. EVEN THE DEPTH OF THE COLD AIR IN THE WAKE OF THE
SYSTEM LOOKS PALTRY COMPARED TO THE EARLIER MODEL SUGGESTIONS. WITH
THE DISAGREEMENT IN THE MODELS FOR THE UPPER PATTERN ON MONDAY HAVE
CHOSEN TO MINIMIZE THE THREAT OF ANOTHER SOUTHERN SYSTEM DEVELOPING
AND AFFECTING EAST KENTUCKY LATE IN THE FORECAST...AS DEPICTED BY THE
12Z GFS.
FOR TEMPS...STAYED FAIRLY CLOSE TO HPC AND MOS GUIDANCE WITH ONLY
LIMITED TERRAIN BASED ADJUSTMENTS THROUGH THE PERIOD. POP-WISE...
WENT CATEGORICAL ON THURSDAY NIGHT INTO FRIDAY...SIMILAR TO THE MEX
GUIDANCE...THEN UNDERCUT THE MOS NUMBERS INTO MONDAY.
&&
.AVIATION.../06Z TO 06Z/
WILL KEEP CONDITIONS MAINLY MVFR/IFR FOR THE REMAINDER OF THE
OVERNIGHT WITH MOSTLY VFR BY LATE MORNING THROUGH THE END OF THE
FORECAST PERIOD. IR SATELLITE IMAGERY SHOWS SOME CLEARING IN THE
SOUTHWESTERN CWA...HOWEVER EXPECT THIS TO ONLY BE TEMPORARY AS MORE
LOWER CIGS ARE EVIDENT TO THE WEST BASED ON OBS. HAVE THESE MVFR/IFR
CIGS ADVECTING BACK INTO EAST KENTUCKY BETWEEN 3 AND 4 AM AND
LINGERING THROUGH LATE MORNING BEFORE SCATTERING OUT. VISIBILITIES
WILL ALSO BE OF CONCERN AS MVFR/IFR RESTRICTIONS ARE CURRENLY IN
PLACE IN BR. MODEL GUIDANCE SUGGEST VISIBILITIES COULD GO BELOW A
MILE SHOULD CIGS STAY MORE SCATTERED...HOWEVER WILL KEEP VISBYS AT
TAF SITES ABOVE 1 MILE AS AMPLE SKY COVER LOOKS TO PREVAIL. EXPECT VFR
BY LATE MORNING...WITH SCATTERED CLOUDS BELOW 2 K FEET AND LIGHT AND
VARIABLE SURFACE WINDS.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...
FREEZING FOG ADVISORY UNTIL 10 AM EST THIS MORNING FOR KYZ044-
050>052-058>060-068-069-079-080-083>088-104-106>120.
&&
$$
SHORT TERM...DUSTY
LONG TERM....GREIF
AVIATION...SCHOETTMER
