Area Forecast Discussion
Issued by NWS Jackson, KY

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000 FXUS63 KJKL 182025 AFDJKL AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE JACKSON KY 325 PM EST THU DEC 18 2014 .SHORT TERM...
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(THIS EVENING THROUGH FRIDAY NIGHT) ISSUED AT 250 PM EST THU DEC 18 2014 19Z SFC ANALYSIS SHOWS HIGH PRESSURE PUSHING INTO THE STATE FROM THE NORTHWEST. AT THE LEADING EDGE OF THIS...TO THE NORTHWEST...A BAND OF LIGHT SNOW AND FLURRIES ARE MOVING EAST OUT OF SOUTHERN INDIANA AND ALONG THE KENTUCKY/OHIO BORDER. ELSEWHERE...SOME VIRGA AND AT WORST A FEW FLURRIES OR SNOW GRAINS...ARE SEEN PASSING THROUGH EASTERN KENTUCKY. ALTHOUGH THERE HAVE BEEN A FEW BREAKS IN THE CLOUDS ACROSS THE SOUTH TODAY MID AND HIGH LEVEL CLOUDS DOMINATED FOR YET ANOTHER DAY. TEMPERATURES THIS AFTERNOON RANGE FROM THE LOW 30S IN THE FAR NORTH WHERE LOW CLOUDS HAVE HELD IN TOUGH FOR MOST OF THE DAY...TO THE LOWER 40S IN THE FAR SOUTHEAST...TAKING ADVANTAGE OF THE BREAKS IN THE SKY COVER. DEWPOINTS THROUGH THE AREA ARE IN THE MID TO UPPER 20S AS THE WINDS CONTINUE TO BE LIGHT OUT OF THE NORTHWEST. THE MODELS ARE IN GOOD AGREEMENT ALOFT AS THEY ALL SHOW FAIRLY FAST AND FLAT CONFLUENCE FLOW OVER KENTUCKY INTO THE DAY FRIDAY BEFORE A WEAK AND DAMPENING TROUGH SLIPS INTO THE TENNESSEE VALLEY FRIDAY NIGHT INTO SATURDAY MORNING. THE SOUTHERN PORTION OF THIS WAVE WILL BE SHEARING OUT IN RESPONSE TO RISING HEIGHTS AND A BETTER DEFINED CLUSTER OF ENERGY MOVING EAST THROUGH THE OHIO VALLEY. THIS IS A PITIFUL RESULT FOR WHAT AT ONE TIME WAS LOOKING LIKE A SIGNIFICANT TROUGH CROSSING THE AREA THIS WEEKEND. THE TRENDS HAVE BEEN FOR A WEAKER AND MORE DAMPENED SYSTEM THROUGH THE PAST HANDFUL OF RUNS. ACCORDINGLY...HAVE FAVORED THE WEAKER SOLUTION FROM THE NAM12 BUT DID BLEND A BIT WITH THE 00Z ECMWF AND 12Z GFS SO IT ISN/T SUCH AN ABRUPT CHANGE TO THE FORECAST. SENSIBLE WEATHER WILL FEATURE A RISK FOR LIGHT SNOW AND FLURRIES TO THE NORTH INTO THIS EVENING...BUT EVEN THIS SHOULD LIFT OFF TO THE NORTH AND EAST OF OUR PART OF KENTUCKY. HIGH PRESSURE WILL KEEP THINGS QUIET...BUT NOT CLOUD FREE...TONIGHT INTO FRIDAY. THE BEST CHANCE FOR CLEARING WILL BE MIDDAY FRIDAY...FOR A TIME...AHEAD OF THE WEAKENING SOUTHERN SYSTEM. THIS NEXT SYSTEM THEN BRUSHES INTO SOUTHERN PARTS OF THE CWA WITH A POTENTIAL FOR LIGHT SNOW...BUT MORE LIKELY JUST FLURRIES GIVEN THE MODEL TRENDS. CHILLY TEMPERATURES CONTINUE THROUGH THE PERIOD WITH DEWPOINTS LOW ENOUGH TO MAKE WETBULBING AN ISSUE FOR ANY PCPN THAT MOVES IN THAT IS NOT VERY LIGHT. THIS WOULD SUPPORT MORE FROZEN RATHER THAN LIQUID PCPN FOR THIS DISAPPOINTING NON EVENT STARTING LATE FRIDAY NIGHT. AGAIN USED THE BCCONSSHORT AS A STARTING POINT FOR THE T/TD/WIND GRIDS FOR THE FIRST 20 HOURS OR SO BEFORE POPULATING WITH THE SUPERBLEND THEREAFTER. ONLY MINOR ADJUSTMENTS WERE MADE FOR TERRAIN EFFECTS BOTH TONIGHT AND FRIDAY NIGHT GIVEN THE CLOUDS. AS FOR POPS...ENDED UP A BIT ABOVE THE MET AND MAV NUMBERS THIS EVENING NORTH AND THEN CLOSER TO THE DRIER MAV ONES FOR FRIDAY NIGHT...AS A STEP TOWARD THE EVEN DRIER MET VALUES SHOULD CURRENT TRENDS PERSIST. .LONG TERM...(SATURDAY THROUGH THURSDAY) ISSUED AT 322 PM EST THU DEC 18 2014 ACTIVE PATTERN IS EXPECTED THROUGH THE LONG TERM PERIOD WITH SEVERAL SYSTEMS EXPECTED TO IMPACT EASTERN KY. FIRST SYSTEM WILL BE ONGOING INTO THE LONG TERM ON SATURDAY. SYNOPTICALLY THERE IS A SHORTWAVE MOVING INTO EASTERN TX TONIGHT AND A AREA OF DEVELOPING LOW PRESSURE ACROSS SOUTHERN TX. THE AREA OF LOW PRESSURE WILL MOVE INTO THE GULF OF MEXICO FRIDAY NIGHT INTO SATURDAY. RIGHT NOW MODELS ARE IN DECENT AGREEMENT WITH THIS...HOWEVER THE MOISTURE LOOKS MORE LIMITED IN THE LATEST RUNS. GIVEN THIS DID OPT TO BRING POPS DOWN AND THIS MAY NEEDED TO CONTINUE TO BE TRENDED IN THAT DIRECTION. TEMPERATURES WILL BE COLD ENOUGH EARLY SATURDAY FOR SNOW BUT AS WE MOVE THROUGH THE DAY EXPECT THAT TO TRANSITION TO ALL RAIN. AFTER THIS WE SEE MORE ZONAL FLOW ALOFT AND SURFACE HIGH CREEPING BACK ACROSS THE REGION BRIEFLY AHEAD OF A AMPLIFIED TROUGH DEVELOPING ACROSS THE CENTRAL US. THIS WILL AID IN DEVELOPING ANOTHER SURFACE LOW PRESSURE ACROSS THE GULF OF MEXICO SUNDAY NIGHT. MOISTURE WILL STREAM NORTH ACROSS THE REGION SUNDAY NIGHT INTO MONDAY. MODELS ARE DIFFERING ON TIMING AND WILL LEAN TOWARD THE BLEND AT THIS POINT. BASED ON THE PROFILES THIS PRECIP WILL BE IN THE FORM OF RAIN ACROSS EASTERN KY. THIS SYSTEM WILL PROGRESS NE ACROSS THE ATLANTIC COAST LINE. ON THE HEELS OF THIS IS YET ANOTHER DEVELOPING SURFACE LOW PRESSURE ACROSS THE UPPER MIDWEST. THIS AMPLIFIED UPPER LEVEL TROUGH WILL EVENTUALLY CUTOFF AS WE MOVE INTO TUESDAY NIGHT AND THIS WILL CONTINUE TO DEEPEN LOW PRESSURE SYSTEM ACROSS THE GREAT LAKES AND OHIO VALLEY. RIGHT NOW THE MODELS CONTINUE TO DIFFER IN THE DEVELOPMENT AND MOVEMENT OF THIS SYSTEM...HOWEVER THE MODELS ARE IN AGREEMENT THAT A FRONTAL BOUNDARY WILL CROSS THE REGION SOMETIME TUESDAY NIGHT INTO EARLY WEDNESDAY. THE ISSUE BECOMES JUST HOW MUCH QPF AND WHEN DO WE SEE THE COLD AIR FILTER INTO THE REGION. GIVEN THIS SETUP WE DO RUN THE RISK OF SOME IMPACTS TO TRAVEL CHRISTMAS EVE DAY TO THE CWA...HOWEVER GIVEN THAT THIS IS IN THE LONGER RANGE PORTION OF THE FORECAST THIS WILL NEED TO BE MONITORED AS WE GET CLOSER TO THAT FORECAST PERIOD. THE UPPER LEVEL TROUGH IS EXPECTED TO CONTINUE TO STRENGTHEN AND NEGATIVELY TILT WEDNESDAY INTO THURSDAY. THIS WILL GIVE WAY TO NW FLOW AND POTENTIAL FOR CONTINUED CHANCES OF SNOW WEDNESDAY INTO WEDNESDAY NIGHT PARTICULARLY ACROSS THE SE PORTIONS OF THE CWA. THIS SYSTEM WILL ALSO HAVE STRONG JET SUPPORT AND SOME OF THIS WILL BE TRANSFERRED TO THE SURFACE. SO EXPECT WINDY CONDITIONS ACROSS THE REGION WEDNESDAY INTO THURSDAY. HIGH PRESSURE TRIES TO BUILD EAST BRIEFLY AS WE MOVE INTO LATER THURSDAY.
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&& .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON) ISSUED AT 125 PM EST THU DEC 18 2014 SURFACE HIGH PRESSURE HAS BASICALLY WON OUT OVER THE AREA... EVAPORATING ALL THE LIGHT RADAR RETURNS BEFORE THEY REACH THE GROUND. THE LOWER CLOUDS ACROSS THE NORTH ARE EXPECTED TO BREAK UP DURING THE AFTERNOON WHILE HIGH AND MID ONES REMAIN. CANNOT RULE OUT AN ODD FLURRY OR SPRINKLE THROUGH THE EVENING...BUT MOST LOCATIONS WILL REMAIN PCPN FREE. THE VFR CIGS WILL LOWER TONIGHT INTO FRIDAY MORNING BUT THERE SHOULDN/T BE ANY RESTRICTIONS. EVEN THESE CLOUDS WILL LIKELY BREAK UP DURING THE DAY FRIDAY KEEPING CONDITIONS VFR. WINDS THROUGH THE PERIOD WILL BE LIGHT AND MAINLY FROM THE NORTHWEST. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...GREIF LONG TERM...DJ AVIATION...GREIF

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