Area Forecast Discussion
Issued by NWS Jackson, KY

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000 FXUS63 KJKL 170627 AFDJKL AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE JACKSON KY 127 AM EST WED DEC 17 2014 .UPDATE... ISSUED AT 116 AM EST WED DEC 17 2014 WITHIN THE LAST COUPLE OF HOURS...DRIZZLE HAS PICKED UP SIGNIFICANTLY ACROSS THE NORTHERN HALF OF THE CWA...TRANSITIONING TO MORE OF A SCATTERED RAIN SHOWER EVENT WITH EMBEDDED AREAS OF DRIZZLE. THERE DOES SEEM TO BE A BACK EDGE TO THIS HEAVIER PRECIP...WHICH IS CURRENTLY MOVING EASTWARD INTO OUR CWA. AS SUCH...HEIGHTENED WORDING FROM DRIZZLE TO SCATTERED RAIN SHOWERS...DIMINISHING FROM WEST TO EAST OVER THE NEXT 6 HOURS AND TRANSITIONING BACK TO DRIZZLE WITH A FEW ISOLATED AREAS OF HEAVIER RAINFALL POSSIBLE THROUGH 12Z. ALSO FRESHENED UP THE NEAR-TERM FORECAST FOR TEMPS...DEW POINTS...AND WINDS...BASED ON THE 5Z OBSERVATIONS. UPDATE ISSUED AT 1105 PM EST TUE DEC 16 2014 DRIZZLE AND SOME EMBEDDED SHOWERS CONTINUE ACROSS EASTERN KENTUCKY. THE HOURLY POPS HAVE BEEN INCREASED TO ISOLATED FOR THE NORTH AND EAST INTO EARLY ON THU. HOURLY TEMPERATURES HAVE BEEN FRESHENED UP BASED ON RECENT OBSERVATIONS. NO SIGNIFICANT CHANGES WERE NEEDED AT THIS TIME. UPDATE ISSUED AT 745 PM EST TUE DEC 16 2014 HOURLY GRIDS HAVE BEEN UPDATED BASED ON RADAR AND OBSERVATION TRENDS. THIS LED TO LOWERING TEMPERATURES IN THE HIGHEST TERRAIN INITIALLY ABOVE 2500 FEET. MODEL PLAN VIEW DATA ALSO SUGGESTED SLIGHTLY LOWER MIN T IN THE HIGHER TERRAIN NEAR BLACK MTN. RAIN SHOWERS CONTINUE ACROSS THE EASTERN PART OF THE CWA...WITH SOME DRIZZLE FURTHER TO THE WEST. MODEL DATA SUGGESTS SUFFICIENT MOISTURE FOR DRIZZLE TO LINGER THROUGH THE NIGHT AND INTO EARLY ON WED. THE HIGHEST TERRAIN SHOULD COOL ENOUGH FOR CHANCES OF FREEZING DRIZZLE ABOVE 2000 FEET. THIS THREAT WILL BEGIN FIRST...IN THE NEXT HOUR OR TWO ON TOP OF BLACK MTN AND THEN GRADUALLY SPREAD TO PINE MOUNTAIN AND POSSIBLY THE LOG MOUNTAINS. && .SHORT TERM...(THIS EVENING THROUGH WEDNESDAY NIGHT) ISSUED AT 315 PM EST TUE DEC 16 2014 19Z SFC ANALYSIS SHOWS A FAIRLY DEEP AREA OF LOW PRESSURE LIFTING NORTHEAST THROUGH THE EASTERN GREAT LAKES. THE COLD FRONT ASSOCIATED WITH THIS SYSTEM IS NOW THROUGH EASTERN KENTUCKY AND AS A RESULT GUSTY WEST WINDS ARE BRINGING IN A COLDER AIR MASS. AS IT DOES SO... IT IS ALSO GENERATING A SUBSTANTIAL AREA OF DRIZZLE AND LOWER CIGS. TEMPERATURES VARY FROM THE LOW 40S WEST TO NEAR 50S EAST ACROSS THE CWA WITH DEWPOINTS IN THE UPPER 30S TO LOWER 40S. THE MODELS ARE IN DECENT ENOUGH AGREEMENT ALOFT THROUGH THE SHORT TERM PORTION OF THE FORECAST AS THEY ALL DAMPEN OUT THE CURRENT TROUGH OVER THE AREA WHILE ABSORBING IT INTO THE MAIN MID LEVEL LOW OVER THE UPPER MIDWEST. THIS WILL KEEP FAST...WEST TO EAST...FLOW ABOVE EASTERN KENTUCKY INTO THE DAY WEDNESDAY...THOUGH MODEL DIFFERENCES START TO MAGNIFY BY DAWN. THE ECMWF IS SLOWER MOVING THIS MIDWEST LOW EAST COMPARED TO THE GEM AND GFS WHICH WILL ALSO SERVE TO KEEP OUR HEIGHTS SLIGHTLY SUPPRESSED INTO WEDNESDAY EVENING. DESPITE THIS...THE PREFERRED ECMWF DOES NOT LAG IN BRINGING THE NEXT BATCH OF ENERGY INTO THE REGION FROM A QUICK MOVING WAVE PASSING OUT OF THE SOUTHERN PLAINS. THIS WILL SEEP INTO OUR SOUTHWEST PARTS BY THURSDAY MORNING. FOR THE FORECAST...FOLLOWED A BLEND OF THE HIGHER RESOLUTION HRRR AND NAM12 WITH SOME ADJUSTMENT TOWARD THE MAIN FEATURES IN THE LATEST ECMWF. A DREARY EVENING AND OVERNIGHT IS ANTICIPATED THROUGH EASTERN KENTUCKY AS LOW CIGS AND DRIZZLE WILL DOMINATE UNDER A SUBSIDENCE INVERSION...PARTICULARLY OVER THE NORTHERN HALF THE CWA. THERE IS A CONCERN THAT THE HIGHER POINTS OF EASTERN KENTUCKY FALL TO FREEZING...OR A COUPLE OF DEGREES BELOW...BY DAWN GIVEN THE CAA OVERNIGHT. COMBINED WITH THE AREAS OF DRIZZLE STILL AROUND...THERE WILL BE A THREAT OF FREEZING DRIZZLE GENERALLY ABOVE 2000 FEET. FOR THIS...WILL ISSUE AN SPS FROM LATE TONIGHT INTO THURSDAY MORNING FOR OUR SOUTHEASTERN-MOST COUNTIES WITH THAT HIGHER TERRAIN. THE LOW CLOUDS WILL PROBABLY HOLD TOUGH INTO THE FIRST PART OF THE DAY WEDNESDAY BUT THERE COULD BE SOME BREAKUP MAKING FOR A BRIEF PERIOD OF SUNSHINE DURING THE AFTERNOON AHEAD OF THE NEXT BATCH OF HIGHER CLOUDS DUE IN HERE LATER THAT EVENING. THESE NEXT CLOUDS WILL QUICKLY INCREASE AND LOWER THROUGH THE NIGHT WITH EVEN SOME LIGHT RAIN OR SNOW POSSIBLE BY DAWN THURSDAY...THOUGH TEMPERATURES WILL BE MILDER THAN TONIGHT IN MOST PLACES. USED THE BCCONSSHORT AS A STARTING POINT FOR THE T/TD/WIND GRIDS FOR THE FIRST 20 HOURS BEFORE POPULATING WITH THE SUPERBLEND THEREAFTER. THESE WERE THEN SUBJECTED TO MINOR ADJUSTMENTS FOR TERRAIN EFFECTS MAINLY TONIGHT AND WEDNESDAY NIGHT. AS FOR POPS...ENDED UP JUST ABOVE THE HIGHER MET MOS GUIDANCE TONIGHT GIVEN THE LOW QPF BUT MODERATE POPS WITH EXTRA EMPHASIS ON DRIZZLE AS PTYPE. ALSO...FOR LATE WEDNESDAY WENT A BIT HIGHER THEN GUIDANCE IN THE SOUTHWEST GIVEN THE FAST FLOW REGIME. .LONG TERM...(THURSDAY THROUGH TUESDAY) ISSUED AT 245 PM EST TUE DEC 16 2014 PROGRESSIVE PATTERN WILL CONTINUE THROUGH THE EXTENDED. THE PERIOD WILL START AS A MID LEVEL TROUGH CROSSES INTO THE OHIO RIVER VALLEY ON THURSDAY. MODELS HAVE TRENDED MORE AGGRESSIVE WITH THIS FEATURE WITH THE 12Z SUITE OF MODELS WITH GFS EVEN SHOWING SOME MODEST LIFT ABOVE 850MB. THE MAIN LIMITING FACTOR FOR PRECIPITATION ON THURSDAY WILL BE THE LOW LEVEL DRY AIR. HOWEVER...GIVEN THE DEEP MOISTURE STARTING AROUND 5KFT...THIS SHOULD BE ENOUGH TO AT LEAST WARRANT A CHANCE OF MEASURABLE PRECIPITATION REACHING THE GROUND. HOWEVER...THIS PRECIPITATION MAY DRY UP AS IT TRIES TO PUSH NORTHWARD THROUGH THE DAY. THUS...PLAN TO GO WITH CHANCE POPS ACROSS THE SOUTH...TRAILING OFF TO SLIGHT CHANCE IN THE NORTH. ALL OF THIS PRECIPITATION AS EXPECTED WILL REMAIN LIGHT...BUT SOME SNOWFLAKES COULD MIX IN AT TIMES THROUGH THE DAY. HIGH PRESSURE WILL PROVIDE DRY WEATHER THURSDAY NIGHT THROUGH FRIDAY. THE WEATHER TURNS MORE INTERESTING BY FRIDAY NIGHT THROUGH SATURDAY AS A SOUTHERN STREAM SHORTWAVE PUSHES EAST ACROSS THE SOUTHERN TIER OF THE US. THIS SYSTEM IS NOT EXPECTED TO GET MUCH HELP FROM THE NORTHERN STREAM...AND THUS...NOT MUCH COLD AIR IS EXPECTED TO GET WORKED INTO THIS SYSTEM. THIS FACT...COMBINED WITH A WEAKENING AREA OF LOW PRESSURE TRACKING ACROSS THE GULF COAST STATES WILL LIKELY YIELD VERY LITTLE SNOW POTENTIAL. HOWEVER...WE ARE ON THE NORTH SIDE OF THIS SYSTEM...WHICH WOULD BE THE BEST SPOT FOR ANY SNOW. PRECIPITATION IS EXPECTED TO SPREAD INTO THE AREA LATE FRIDAY NIGHT AND CONTINUE THROUGH SATURDAY. BEST SNOW POTENTIAL MAY BE AT THE ONSET FRIDAY NIGHT...BUT AGAIN...PRECIPITATION RATES MAY BE FAIRLY LIMITED...KEEPING SNOW AMOUNTS FROM BEING ALL THAT HIGH. IN FACT...WE COULD SEE A MIX OF RAIN/SNOW RIGHT THROUGH SATURDAY WITH VERY LITTLE SNOW ACCUMULATION FOR MUCH OF THE AREA. THE ECMWF REMAINS THE COLDER OF THE MODELS SUGGESTING BETTER SNOW POTENTIAL...WHILE THE GFS HAS MAINTAINED ITS ALL RAIN FORECAST. GOING WITH A COMPROMISE ON HIGHS ON SATURDAY WOULD BE TEMPERATURES AROUND 40 BY THE AFTERNOON ACROSS MUCH OF THE AREA. ITS POSSIBLE SOME COOLER READINGS IN THE 30S COULD KEEP MORE SNOW GOING A BIT LONGER ACROSS THE NORTHERN PORTION OF THE AREA...BUT WITH WEAK PRECIP RATES...COMBINED WITH ABOVE FREEZING TEMPERATURES...SHOULD REALLY CUT INTO ANY SNOWFALL POTENTIAL EVEN WITH THE COLDER ECMWF SOLUTION. PRECIPITATION WILL WIND DOWN BY SATURDAY NIGHT GOING OVER TO A PERIOD OF LIKELY DRIZZLE. DRY WEATHER WILL RETURN FOR SUNDAY AND PERSIST INTO THE EARLY PART OF NEXT WEEK. TEMPERATURES ARE EXPECTED TO REMAIN FAIRLY SEASONABLE THROUGH THE END OF THE FORECAST PERIOD. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z WEDNESDAY NIGHT) ISSUED AT 127 AM EST WED DEC 17 2014 WHILE AREAS OF DRIZZLE ARE ONGOING ACROSS MUCH OF EASTERN KY...THE NORTHEAST PORTION OF THE STATE /GENERALLY AREAS NORTH OF THE MOUNTAIN PARKWAY/... HAVE ACTUALLY SEEN A INCREASE FROM DRIZZLE TO LIGHT RAIN SHOWERS. EXPECT THIS RAIN TO HAVE LITTLE DIFFERENCE IN IMPACTS TO THAT OF THE DRIZZLE...SO WILL JUST CONTINUE WITH DRIZZLE MENTION AT THIS TIME IN TAFS...ESPECIALLY GIVEN THAT THE RAIN SHOWERS SHOULD TAPER OFF AT KSYM...KJKL...AND KSJS OVER THE NEXT COUPLE HOURS. MEANWHILE...CIGS SHOULD REMAIN BETWEEN IFR AND MVFR THROUGH THE REMAINDER OF THE NIGHT...THEN MVFR THROUGH A MAJORITY OF THE DAY TOMORROW...AT LEAST UNTIL DRY AIR IS FINALLY ABLE TO MIX DOWN TO THE SURFACE...CUTTING OFF DRIZZLE POTENTIAL...AND SLOWLY BREAKING THE LOW CLOUD DECK. LATEST GFS FORECAST SOUNDINGS ARE SHOWING THIS OCCURRING SOMETIME BETWEEN 18 AND 21Z...WHILE THE NAM TRIES TO HOLD ON TO THE MOISTURE A BIT LONGER. LEANED MORE TOWARDS THE GFS SOLUTION AT THIS TIME. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...JMW SHORT TERM...GREIF LONG TERM...KAS AVIATION...JMW

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