FXUS63 KJKL 260552
AFDJKL
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JACKSON KY
1252 AM EST SAT DEC 26 2009
.SHORT TERM.../THE REST OF TONIGHT/
PRECIPITATION HAS ENDED ACROSS THE CWA AS COLD/DRY AIR ADVECTION WILL
CONTINUE FOR THE REST OF THE NIGHT. A GRADUAL SLACKENING TREND OF THE
WINDS WILL ALSO CONTINUE THROUGH THE OVERNIGHT PERIOD. TEMPERATURES
ARE STILL A BIT TRICKY AS SURFACE WINDS ARE KEEPING THINGS MIXED...
HOWEVER SKY COVER IS RAPIDLY DECREASING. FEEL THAT WINDS WILL SLACKEN
EARLY ENOUGH FOR GOOD RADIATIONAL COOLING BY DAWN AND HAVE KEPT
TEMPERATURES PRETTY MUCH IN LINE WITH PREVIOUS FORECAST. THIS REMAINS
BELOW MAV/MET GUIDANCE. FOR THE UPDATED ZFP...DECREASED SKY COVER AND
INCREASED WINDS BASED ON LATEST OBS. ALSO REMOVED SLIGHT CHANCE POPS
AS LAPS SOUNDING INDICATE MOISTURE LAYER TOO SHALLOW FOR PRECIP ATTM.
THE PREVIOUS SHORT TERM FORECAST DISCUSSION FOLLOWS...
/TONIGHT THROUGH SUNDAY/
19Z SFC ANALYSIS SHOWS DEEP LOW PRESSURE CENTERED OVER IOWA WITH AN
ELONGATED COLD/OCCLUDED FRONT ARCING SOUTHEAST AND THROUGH FAR
EASTERN KENTUCKY. THE BAND OF MODERATE SHOWERS PRECEDING THE FRONT
HAS SHIFTED EAST ONTO THE OTHER SIDE OF THE APPALACHIANS. LIGHT
SHOWERS AND SPRINKLES ARE ALL THAT REMAIN TO THE WEST...DAMPENING
MAINLY JUST OUR NORTHWEST COUNTIES. THIS FRONT ALSO MARKS A RETURN OF
CLOUDS AFTER THE EASTERN PART OF OUR CWA ENJOYED SOME DRY SLOT
SUNSHINE. THIS SUNSHINE HELPED PROP TEMPERATURES UP INTO THE MID
AND UPPER 50S THROUGH MUCH OF EAST KENTUCKY...BUT NOW BRISK SOUTHWEST
WINDS IN THE FRONT/S WAKE ARE BRINGING IN MUCH COLDER AIR ALREADY
SENDING READINGS DOWN INTO THE LOWER 40S IN THE CUMBERLAND VALLEY.
SIMILAR TO THE SOUTHEAST WINDS AHEAD OF THE BOUNDARY...THESE WINDS
CONTINUE TO BLOW AT SPEEDS OF 15 TO 25 MPH WITH OCCASIONAL GUSTS TO
35 MPH. WHILE THE PRESSURE GRADIENT WILL KEEP THE WINDS UP FOR
SEVERAL MORE HOURS...WE SHOULD BE ON THE BACKSIDE OF THE HIGHER WIND
THREAT NOW...WITH SUNSET LIKELY FURTHER SETTLING THE WINDS.
ACCORDINGLY...OUR LAKE WIND ADVISORY FOR MOST OF THE AREA AND WIND
ADVISORY FOR THE VIRGINIA BORDER COUNTIES WILL BE ALLOWED TO EXPIRE
AS SCHEDULED AT 4 PM EST.
THROUGH THE FIRST PART OF THE SHORT TERM THE MODELS ARE IN GOOD
AGREEMENT ALOFT WITH THE WHIRLIGIG PATH OF THE DEEP UPPER LOW AS IT
INITIALLY LIFTS INTO SOUTHERN LAKE MICHIGAN TONIGHT AND THEN ROLLS
BACK AROUND ITSELF TO THE WEST...RETURNING TO CENTRAL INDIANA...AT
LEAST IN THE ECMWF SOLUTION...BY SUNDAY EVENING. SOMEWHERE IN EASTERN
IOWA SUNDAY MORNING THE MODELS...NOT SURPRISINGLY...BEGIN TO DEVIATE
WITH THE GFS SLIDING EAST QUICKER THAN THE NAM AND ECMWF. THIS TREND
CONTINUES SUNDAY WITH THE ECMWF THE MIDDLE OF THE PACK BUT ALSO THE
FURTHEST SOUTH. FOLLOWED A BLEND THROUGH SATURDAY NIGHT AND THEN
LEANED MORE HEAVILY ON THE ECMWF AS A GOOD COMPROMISE FOR WEATHER
SPECIFICS THROUGH THE END OF THE SHORT TERM.
SENSIBLE WEATHER WILL FEATURE THE WINDS GRADUALLY DIEING DOWN THIS
EVENING AS THE GRADIENT SLOWLY RELAXES OVER THE AREA...AND THE SUN
SETS. LINGERING LIGHT RAIN SHOWERS AND SPRINKLES WILL MIX AND CHANGE
TO SNOW BY LATE EVENING. THIS WILL MAINLY AFFECT OUR NORTHWEST
COUNTIES AND LEAVE BEHIND NO ACCUMULATION. MUCH COLDER AIR PUSHES
INTO THE AREA TONIGHT ON THOSE SOUTHWEST WINDS SENDING TEMPERATURES
DOWN INTO THE UPPER 20S IN MOST LOCATIONS. SKY COVER WILL BE A MORE
QUESTIONABLE ISSUE AS THE MODELS IMPLY CLEARING LATER THIS EVENING...
BUT AN AWFUL LOT OF CLOUDS REMAIN THROUGH THE TENNESSEE VALLEY.
HOWEVER...THE VISIBLE SATELLITE WOULD SUGGEST THAT THESE CLOUDS
ARE NOT THAT THICK AND SOME HOLES HAVE BEEN POPPING UP THROUGHOUT THE
CLOUD MASS THIS AFTERNOON. FOR THE GRIDS...HAVE THE SKY COVER
BREAKING UP TO PARTLY CLOUDY LATER THIS EVENING WITH THE LOSS OF
INSOLATION. SATURDAY WILL ALSO FEATURE PARTLY CLOUDY SKIES WITH THE
SUNSHINE TRYING HARD TO MAKE UP FOR LIMITED CAA ON A CONTINUED
SOUTHWEST WIND FLOW. COLD TEMPERATURES ALOFT WILL PROMPT CLOUDS TO
INCREASE DURING THE AFTERNOON...BUT DRY CONDITIONS WILL PREVAIL. FOR
SATURDAY NIGHT AND SUNDAY THE MOISTURE THAT WRAPPED AROUND THE LARGE
SFC CIRCULATION WILL CREEP INTO THE AREA AS THE LARGE STACKED LOW
DRIFTS EAST JUST NORTH OF KENTUCKY. AS IT DOES SO A VORT STREAM WILL
PRESS BACK INTO THE STATE ACTIVATING THE AVAILABLE MOISTURE TO YIELD
SNOW SHOWERS DEVELOPING...PARTICULARLY IN OUR NORTHERN AND WESTERN
COUNTIES WHERE 30 TO 40 POPS HAVE BEEN DRAWN IN THE GRIDS. LIGHT SNOW
ACCUMULATIONS WILL BE POSSIBLE WITH THIS BUT THEY WILL BE MITIGATED
BY DAYTIME INSOLATION.
AGAIN FOR TEMPS...CHOSE TO FOLLOW A DIURNAL CURVE FROM THE NAM AS MAX
AND MIN TEMPS FROM THE MET WHERE PREFERRED. FOR POPS...THE GUIDANCE
WAS SIMILAR AND MATCH UP WELL WITH OUR POPS.
.LONG TERM.../SUNDAY NIGHT THROUGH FRIDAY/
LINGERING CHANCE OF SNOW SUNDAY NIGHT WILL STILL HAVE A SIGNIFICANT
BUT WEAKENING SHORTWAVE TO GENERATE POSSIBLE SNOW SHOWERS BUT THE
MOISTURE IS NOT AS DEEP AS EARLIER MODEL RUNS. SLIGHT CHANCE OF
MEASURING SNOW APPEARS SUFFICIENT ATTM.
GFS/ECMWF/CANADIAN AGREE IN A COLD FRONT PASSING EAST KENTUCKY ON
THU WHICH WILL STRENGTHEN THERMAL GRADIENT FOR FRONT OVER GA/FL AREA
AND DEVELOPING SURFACE LOW IN NORTHEAST GULF OF MEXICO BY 12Z FRI
MORNING. UNTIL THEN...MOISTURE IS EXPECTED BY GFS/ECMWF POOLING OVER
SOUTHWEST GULF OF MEXICO WILL BE DRAWN NORTHWARD BEGINNING LATE MON
AND ALONG THE FRONT TO ARRIVE THU BUT WITH LITTLE RESULTANT QPF IN
MODELS...SOMETHING OF CONCERN TO PAY ATTENTION TO. POSITION OF AND
HOW AMPLIFIED THE APPROACHING 5H SHORTWAVE WILL BE BY FRI DETERMINES
THE PATH OF THE NEXT STRONG DEVELOPING LOW MOVING NEAR EAST COAST.
GFS AND ECMWF STILL DIFFER GREATLY IN THIS AREA THOUGH MEX 24 HR
POPS ROSE TO LIKELY FOR OUR CWA FOR REASONS NOT ENTIRELY CLEAR.
CHANGED TEMPERATURES LITTLE. UPPER FLOW TO STILL BE SUPPRESSED
SOUTHWARD WHICH HELPS TEMPERATURES STAY SLIGHTLY BELOW SEASONAL
LEVELS.
&&
.AVIATION.../06Z TO 06Z/...UPDATED
EXPECT VFR ENTIRE PERIOD AS THE AREA IS UNDER THE DRY SLOT AND
SURFACE RIDGING. WIND WILL PICK UP A LITTLE THIS AFTERNOON WITH WIND
GUSTS MAXING OUT BETWEEN 15 AND 20 KTS.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
SHORT TERM...GREIF/SCHOETTMER
LONG TERM....GV
AVIATION...JJ
