Area Forecast Discussion
Issued by NWS Jackson, KY

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000 FXUS63 KJKL 290848 AFDJKL AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE JACKSON KY 348 AM EST MON DEC 29 2014 .SHORT TERM...
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(TODAY THROUGH TUESDAY) ISSUED AT 347 AM EST MON DEC 29 2014 THIS MORNING WSR-88D RADAR CONTINUES TO INDICATE AN AREA OF RAIN AND DRIZZLE TRACKING ACROSS PORTIONS OF THE SOUTHERN AND EASTERN PARTS OF THE CWA. THE HRRR HAS NOT BE HANDLING THIS THE BEST AND WAS TOO SLOW...BUT THE 00Z RUN OF THE NAM DID HAVE A HINT OF THE ACTIVITY MOVING ACROSS. THEREFORE LEANED TOWARD IT FOR A PORTION OF THE PERIOD. THIS HAS BEEN AIDED BY SHORTWAVE ENERGY AND LOW PRESSURE ALONG AND NEAR THE FRONTAL BOUNDARY TO THE EAST. THIS ACTIVITY WILL SLOWLY MOVE EAST THROUGH THE DAY TODAY WITH SLIGHT CHANCES OF PRECIP PERSISTING ACROSS THE FAR SOUTHEAST. SOME OF THE ACTIVITY ACROSS THE FAR SOUTHEAST COULD SWITCH OVER TO SOME LIGHT SNOW OR RAIN/SNOW MIX TONIGHT BEFORE ACTIVITY SLOWLY DIES OFF AS COLD AIR MOVES INTO THE REGION. GIVEN MINIMAL MOISTURE WOULD NOT EXPECT ANY ACCUMULATIONS WITH THIS CHANGE OVER. MUCH OF THE REGION IS EXPECTED TO STAY MOSTLY CLOUDY TODAY INTO TONIGHT...HOWEVER PORTIONS OF THE FAR NW COULD SEE SOME PARTLY CLOUDY SKIES BUILDING IN LATE TONIGHT AS HIGH PRESSURE SLOWLY BUILDS EAST. MOVING INTO TUESDAY HIGH PRESSURE WILL CONTINUE TO BUILD EAST INTO THE REGION WITH MODEL SOUNDINGS FINALLY INDICATING SOME DRIER AIR FILTERING INTO THE REGION. THIS WILL GIVE WAY TO PARTLY TO MOSTLY SUNNY SKIES BUT NEAR TO BELOW NORMAL TEMPERATURES FOR THE DAY ON TUESDAY WITH HIGHS IN THE LOWER 40S SOUTH AND MID TO UPPER 30S NORTH. .LONG TERM...(TUESDAY NIGHT THROUGH SUNDAY) ISSUED AT 347 AM EST MON DEC 29 2014 MODELS APPEAR TO BE IN DECENT AGREEMENT UNTIL THE LAST 24 TO 48 HOURS OF THE EXTENDED. BOTH THE NORTHERN AND SOUTHERN STREAMS ARE ACTIVE THROUGH THE PERIOD AS SHORTWAVES SPEED EASTWARD THROUGH BROAD CYCLONIC FLOW ACROSS THE NORTHERN TIER AND A CUT OFF LOW THAT GENERALLY TRACKS FROM CA/NV THROUGH THE DESERT SOUTHWEST AND ACROSS THE SOUTHERN CONUS. THIS LOW THEN MERGES WITH THE NORTHERN STREAM AS IT PASSES THROUGH THE EASTERN CONUS TOWARDS THE END OF THE EXTENDED. MAIN DIFFERENCES BETWEEN THE ECMWF AND GFS OCCUR WITH THE TIMING AT WHICH THE CUTOFF LOW MERGES BACK INTO THE NORTHERN STREAM. THE MORE CONSISTENT GFS IS PROGRESSIVE AND FURTHER NORTH WITH THE TRACK OF THE LOW WHILE THE ECMWF IS SLOWER AND FURTHER SOUTH WITH THIS FEATURE. AN APPARENT REVERSAL FROM PREVIOUS CYCLES. DIFFICULT DECISION WHETHER TO RELY ON THE MORE CONSISTENT GFS OR THE TYPICALLY BETTER PERFORMING ECMWF WHICH ALSO HAS A HISTORY FOR BEING BETTER AT PICKING UP ON NEW TRENDS. FOR NOW WILL STICK WITH A TRUE BLEND...OR MODEL CONSENSUS FOR THE FORECAST. A VERY WEAK UPPER LEVEL SHORTWAVE TROUGH WILL PROVIDE A GLANCING BLOW TO OUR FORECAST AREA EARLY IN THE PERIOD...WEDNESDAY. THIS FEATURE WILL NOT PRODUCE ANY SENSIBLE WEATHER BUT WILL SEND A REINFORCING SHOT OF COLDER AIR INTO OHIO VALLEY. THAT LEAVES AS OUR MAIN WEATHER MAKER FOR THE EXTENDED THE AFOREMENTIONED CUTOFF LOW. AS IS ALMOST ALWAYS THE CASE FOR THESE TYPES OF SITUATIONS...THE EXACT TRACK AND TIMING OF THE LOW ACROSS THE EASTERN CONUS WILL BE THE DETERMINING FACTOR IN OUR SENSIBLE WEATHER. THE ECMWF HAS TRENDED FURTHER SOUTH...WITH A COLDER SOLUTION AND A BETTER POTENTIAL FOR SOME TYPE OF WINTRY WEATHER FOR PORTIONS OF THE OHIO VALLEY. THE GFS IS WARMER AND WETTER WITH ITS SOLUTION.
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&& .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z MONDAY NIGHT) ISSUED AT 100 AM EST MON DEC 29 2014 FRONTAL BOUNDARY HAS MOVED SOUTH OF THE REGION TONIGHT WITH SURFACE LOW RIDING UP ACROSS THE CAROLINA/TENNESSEE BORDER INDICATED BY 03Z SURFACE ANALYSIS. MOST OF THE HEAVIER RAIN SHOWER ACTIVITY HAS MOVED SOUTH OF THE REGION TONIGHT...HOWEVER DRIZZLE OR ISOLATED SHOWERS WILL BE POSSIBLE OVERNIGHT. TAF SITES HAVE BEEN FLUCTUATING TONIGHT WITH MOST SITES SEEING IFR TO LIFR CONDITIONS. SOME DRIER AIR HAS BEEN ABLE TO TO MAKE IT INTO NW PORTIONS OF THE CWA WITH SYM CIGS MVFR...HOWEVER FOG IS EXPECTED TO STILL BE A ISSUE AT MOST SITES AND COULD BRING LOWER CONDITIONS TO THESE SITES THAT SEE THE HIGHER CIGS. MOVING INTO TOMORROW MORNING WOULD EXPECT SOME IMPROVEMENTS TO THE TAF SITES AS FOG LIFTS SLOWLY...BUT MOST SITES ARE ONLY EXPECTED TO IMPROVE TO MVFR CONDITIONS AS WE MOVE INTO TOMORROW. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...DJ LONG TERM...RAY AVIATION...DJ

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