Area Forecast Discussion
Issued by NWS Jackson, KY

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000 FXUS63 KJKL 270608 AFDJKL AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE JACKSON KY 108 AM EST SAT DEC 27 2014 .UPDATE... ISSUED AT 919 PM EST FRI DEC 26 2014 FORECAST SEEMS TO BE WELL ON TRACK AT THIS POINT. HIGH CLOUDS ARE CONTINUING TO MOVE INTO EASTERN KY AND WILL THICKEN THROUGHOUT THE NIGHT. MEANWHILE...LIGHT RETURNS ARE STARTING TO SHOW UP ON THE RADAR. GIVEN THE ABUNDANT AMOUNT OF LOW AND MID LEVEL DRY AIR...THESE RETURNS ARE DROPPING FROM HIGH ALTITUDES AND THEN EVAPORATING BEFORE HITTING THE GROUND. AS SUCH...HAVE NOT INCLUDED ANY MENTION OF RAIN IN THE FORECAST UNTIL THE SYSTEM BEGINS IMPACTING THE REGION. LOADED IN THE LATEST OBSERVATIONAL DATA FOR TEMPS...DEW POINTS...AND WINDS...TO MAKE SURE THE NEAR TERM GRIDS WERE ON TRACK WITH ONGOING CONDITIONS. THIS RESULTED IN LITTLE CHANGE FROM THE CURRENT FORECAST. && .SHORT TERM...(THIS EVENING THROUGH SATURDAY NIGHT) ISSUED AT 328 PM EST FRI DEC 26 2014 MODELS ARE IN GOOD AGREEMENT THROUGH THE SHORT TERM WILL ONLY SOME TIMING DIFFERENCES TO DEAL WITH FROM THE HIGHER RESOLUTION 12Z NAM. BUT 18Z RUN OF THE NAM HAS SLOWED ONSET OF PRECIPITATION INTO THE AREA LATE SATURDAY...NOW MORE IN LINE WITH THE GFS AND ECMWF. MID/UPPER LEVEL RIDGE...CENTERED OVER CUBA HAS AMPLIFIED SLIGHTLY OVER THE CENTRAL AND SOUTHERN APPALACHIANS DUE TO THE EASTWARD MOVEMENT OF A TROUGH LIFTING OUT OF THE WESTERN GREAT BASIN... SOUTHWEST CONUS. AT THE SFC...FAIRLY STATIONARY HIGH PRESSURE WAS CENTERED OVER THE CENTRAL ATLANTIC COASTAL REGION KEEPING OUR AREA UNDER THE INFLUENCES OF SOUTHERLY FLOW. STRONG SUBSIDENCE WAS RESPONSIBLE FOR VERY DRY AIR MIXING INTO THE TOP OF THE BOUNDARY LAYER EARLIER TODAY BUT DEW POINTS HAVE RECOVERED SOME THIS AFTERNOON. POSITION OF THIS HIGH AND DRY AIR AT THE SFC WILL BE FAVORABLE FOR A STRONG RIDGE VALLEY SPLIT ACROSS THE AREA TONIGHT. CONTINUED MOVEMENT OF MID/UPPER LEVEL TROUGH OUT OF THE WESTERN CONUS WILL INDUCE A SERIES OF SFC LOWS...THE FIRST DEVELOPING OVER THE EASTERN PLAINS AND MOVING INTO THE GREAT LAKES BY SATURDAY. THIS FIRST LOW WILL DRAG A SFC COLD FRONTAL BOUNDARY INTO THE OHIO VALLEY SATURDAY NIGHT INTO SUNDAY MORNING. A SECOND LOW WILL DEVELOP MUCH FURTHER SOUTH OVER THE SOUTHERN MISSISSIPPI VALLEY REGION AND TRACK NORTHEAST ALONG THE FRONT AS IT PUSHES ACROSS THE APPALACHIANS EARLY SUNDAY MORNING. THIS WILL TEND TO KEEP OUR WEATHER WET THROUGH TO THE END OF THE SHORT TERM. FOR SENSIBLE WEATHER...MID AND HIGH LEVEL CLOUDS WILL ENTER OUR AREA LATE THIS AFTERNOON INTO THIS EVENING...THEN THICKEN AND LOWER WITH TIME. TIMING THE ONSET OF SHOWER ACTIVITY INTO THE AREA LATE SATURDAY IS MAIN FORECAST CHALLENGE. BUT A BLEND OF SOLUTIONS SUGGESTS SCATTERED SHOWERS ENTERING OUR WESTERN MOST COUNTIES LATE SATURDAY AFTERNOON AND OVERSPREADING THE REST OF OUR FORECAST AREA SATURDAY NIGHT. INCREASED POPS TO CATEGORICAL LEVELS SATURDAY NIGHT. FOR TEMPS...WENT COLD IN OUR VALLEYS AREA TONIGHT....ESPECIALLY IN OUR EAST WHERE SOUTHERLY WINDS WILL NOT BE STRONG TO MIX THE NOCTURNAL INVERSION OUT. HIGHS SATURDAY WILL RUN 3 TO 5 DEGREES WARMER THAN TODAY...WITH A RELATIVELY BROKEN SKY COVER TENDING TO KEEP HIGHS DOWN A BIT. CLOUD COVER AND RAINFALL WILL MODERATE LOWS SATURDAY NIGHT INTO SUNDAY MORNING...WITH MOST LOCATIONS ONLY DROPPING INTO THE MID 40S. .LONG TERM...(SUNDAY THROUGH FRIDAY) ISSUED AT 407 PM EST FRI DEC 26 2014 THE EXTENDED FORECAST PERIOD BEGINS WITH AN ELONGATED TROUGH MOVING THROUGH THE MIDWEST AND INTO THE APPALACHIAN CHAIN. THE SOUTHERN PORTION OF THE TROUGH DEVELOPS A STRONGER SHORTWAVE ALONG THE GULF COAST AS IT BEGINS TO RIDE TO THE NORTHEAST OVER THE RIDGE LOCATED IN THE BAHAMAS. AS THIS FEATURE AND ASSOCIATED LONG WAVE TROUGH EXITS THE EASTERN CONUS...THE UPPER LEVEL PATTERN TRANSITIONS TO A BROAD TROUGH EXTENDED ENTIRELY ACROSS THE LOWER CONUS WITH A CLOSED LOW DIVING SOUTH ALONG THE WEST COAST AND INTO THE BAJA REGION. MODELS STILL HAVE THIS FEATURE EJECTING EASTWARD INTO THE GULF COAST REGION. AT THE SURFACE...CONCERNING THE SUNDAY THROUGH MONDAY TIME FRAME THE FRONT WILL BE MOVING THROUGH EASTERN KENTUCKY ON SUNDAY WHILE SLOWING ALONG THE APPALACHIAN CHAIN. THIS WILL RESULT IN A LONGER DURATION OF RAINFALL ACROSS THE AREA BEFORE EXITING MONDAY NIGHT. WHILE SOME COLDER AIR WILL BE FILTERING IN BEHIND THIS FRONT...THERE MAY BE A FEW LOCATIONS THAT WILL SEE A MIX OR CHANGE OVER TO SOME SNOW BUT NO ACCUMULATION IS EXPECTED SINCE THE DURATION WILL BE SO SHORT IF AT ALL. QUITE A COLDER AIR MASS WILL FILTER INTO THE OH VALLEY TOWARD MID NEXT WEEK. THIS COLDER AIR WILL BE IN PLACE FOR THE ARRIVAL ON THE NEXT SYSTEM MOVING UP FROM THE SOUTH ON THURSDAY AND WILL RESULT IN SOME SNOWFALL IN SOUTHEAST KENTUCKY. ANY ACCUMULATION IS QUITE UNCERTAIN AT THIS POINT. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT) ISSUED AT 108 AM EST SAT DEC 27 2014 LOOK FOR VFR CONDITIONS THROUGH THE ENTIRE FORECAST PERIOD. RADAR IS PICKING UP ON A RATHER LARGE AREA OF LIGHT ECHOS TONIGHT. HAVE EVEN SEEN SOME -IP/-RA HERE AT JKL AS ONE CELL INTENSIFIED SUDDENLY. BUT THE BULK OF THIS ACTIVITY IS VIRGA AND AS SUCH DID NOT MENTION ANY WEATHER AT ANY OF OUR TERMINALS. ALSO EXPECT THIS ACTIVITY TO WANE AS WE PROGRESS THROUGH THE EARLY MORNING HOURS. ADDITIONAL SHOWERS ASSOCIATED WITH AN APPROACHING COLD FRONTAL SYSTEM WILL DEVELOP DURING THE LAST FEW HOURS OF THE FORECAST. CIGS AND VSBYS WILL DROP THEREAFTER...JUST BEYOND THE FORECAST WINDOW. WINDS WILL RUN LESS THAN 10 KTS THROUGH THE PERIOD...AND GENERALLY FROM THE S/SW. && .JKL WATCHES/WARNINGS/ADVISORIES...NONE. && $$ UPDATE...JMW SHORT TERM...RAY LONG TERM...SHALLENBERGER AVIATION...RAY

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