Area Forecast Discussion
Issued by NWS Jackson, KY

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000 FXUS63 KJKL 251746 AFDJKL AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE JACKSON KY 1246 PM EST THU DEC 25 2014 .UPDATE... ISSUED AT 1246 PM EST THU DEC 25 2014 WILL BE UPDATING THE FORECAST PACKAGE TO HANG ONTO CLOUDS JUST A BIT LONGER AS PESKY LOW SC DECK GRADUALLY DISSIPATES THROUGH THE LATE AFTERNOON AND EARLY EVENING TIME FRAME. OTHERWISE JUST MINOR TWEAKS TO THE HOURLY GRIDS TO ACCOUNT FOR LATEST OBSERVATIONS. UPDATE ISSUED AT 938 AM EST THU DEC 25 2014 UPDATED GRIDS FOR LATEST HOURLY OBS AND TRENDS. THIS RESULTED IN VERY MINOR CHANGES TO THE FORECAST. OVERALL FORECAST IS IN EXCELLENT SHAPE THIS CHRISTMAS MORNING. STILL PICKING UP ON SOME PATCHY DRIZZLE IN THE OBS AND ON RADAR. CLOUD TOP TEMPS SUGGEST THERE IS SOME FLURRY ACTIVITY OUT THERE AS WELL...MAINLY IN THE HIGHER ELEVATIONS. NO UPDATE TO THE ZONES PLANNED AT THIS TIME. UPDATE ISSUED AT 745 AM EST THU DEC 25 2014 HOURLY GRIDS HAVE BEEN FRESHENED UP BASED ON RECENT RADAR AND OBSERVATION TRENDS. THIS LED TO HOLDING ONTO CHANCES FOR DRIZZLE A BIT LONGER IN MANY AREAS. FLURRIES WILL ALSO BE POSSIBLE INITIALLY ABOVE 2000 FEET. HOWEVER...THE MOISTURE WILL BECOME MORE SHALLOW THIS MORNING AND EVENTUALLY STRATOCU SHOULD BE LEFT BEHIND. THIS STRATOCU SHOULD BEGIN TO SCATTER OUT BY EARLY TO MID AFTERNOON IN WESTERN LOCATIONS. && .SHORT TERM...(TODAY THROUGH FRIDAY) ISSUED AT 325 AM EST THU DEC 25 2014 A DEEP CLOSED UPPER LEVEL LOW AND SFC SYSTEM CONTINUES TO DEPART TO OUR NORTH AND NORTHEAST WITH THE TRAILING UPPER LEVEL TROUGH NOW WORKING ACROSS PARTS OF THE GREAT LAKES...OH VALLEY AND APPALACHIANS. MEANWHILE TO THE WEST...A RIDGE EXTENDED FROM THE PACIFIC TO THE SOUTHWEST OF BAJA INTO THE SOUTHERN AND CENTRAL PLAINS REGION. ALSO AT THE SFC...A RIDGE OF HIGH PRESSURE EXTENDED NORTH FROM THE WESTERN GULF OF MEXICO NORTH INTO THE MS VALLEY REGION. SOME SHOWERS...LIKELY MIXED WITH OR ALL RAIN ABOVE 2000 FEET ARE WORKING FROM THE KY CUMBERLAND MTNS EAST INTO THE WESTERN VA MOUNTAINS. ADDITIONAL ISOLATED SHOWERS OR PATCHES OF DRIZZLE HAVE DEVELOPED FURTHER TO THE WEST NEARER TO THE I 75 CORRIDOR AS THE UPPER LEVEL TROUGH AXIS WORKS THROUGH THE AREA AND CORE OF THE COLDEST 850 MB AIR AND SLIGHTLY STEEPER LAPSE RATES MOVE IN. CURRENTLY ACROSS THE HIGH TERRAIN THE TO OF BLACK MTN AT NEAR 4100 FEET IS 30 DEGREES WHILE THE FLATWOODS MESONET SITE IN PIKE COUNTY NEAR 2800 FEET IS 34 DEGREES. LOWER ELEVATION TEMPERATURES ARE GENERALLY IN THE UPPER 30S TO LOWER 40S. THE PRIMARY WEATHER CONCERN FOR THE SHORT TERM PERIOD IS THE LIGHT PRECIP THROUGH AROUND DAWN AS THE TROUGH WORKS THROUGH AND THEN THE LOW LEVEL MOISTURE SUBSEQUENTLY BECOMES MORE SHALLOW AND A PERIOD OF STRATOCU FOLLOWS. ABOVE 2000 FEET SNOW OR A RAIN AND SNOW MIX IS ANTICIPATED AS CLOUD TOP TEMPS NEAR THE RETURNS TO OUR WEST ARE GENERALLY -11C TO -14C OR SUPPORTIVE OF THE PRESENCE OF ICE IN THESE CLOUDS. ALSO IN THESE AREAS ABOVE 2000 FEET MIN T SHOULD REACH 32 OR LOWER. LOWER ELEVATION LOCATIONS WILL BOTTOM OUT IN THE MID TO UPPER 30S. THERE ARE AREAS WITH WARMER TEMPS AND ANY LIGHT PRECIP FALLING FROM THEM WOULD BE MORE OF A DRIZZLE. SOME RECENT SHORT TERM GUIDANCE SUCH AS THE HRRR AND RAP GUIDANCE SUPPORTS ONE LAST UPTICK IN COVERAGE OF THIS LIGHT PRECIP AS IT WORKS ACROSS THE REGION OVER THE NEXT 3 TO 5 HOURS...ENDING NOT LONG AFTER SUNRISE. ACCORDINGLY...A PRE FIRST PERIOD WAS USED IN THE ZFP AND THE HWO HIGHLIGHTED THE SMALL CHANCE FOR SNOW SHOWERS INITIALLY FOR THE 4 VA BORDER COUNTIES. OTHERWISE...BEHIND THE DEPARTING TROUGH...HIGH PRESSURE WILL BUILD INTO AND THEN ACROSS THE AREA BEFORE SHIFTING TO THE EAST OF THE AREA ON FRIDAY. THIS WILL LEAD TO GRADUALLY CLEARING SKIES FROM WEST TO EAST TODAY AND DRY WEATHER FOR TONIGHT AND FRIDAY. THIS PATTERN WILL FAVOR A RIDGE/VALLEY TEMPERATURE SPLIT FOR TONIGHT WITH THE DEEPER VALLEY LOCATIONS AND TYPICAL COLD SPOTS REACHING THE MID 20S. A VERY DRY AIR MASS PROJECTED FOR FRIDAY WILL WARM WELL INTO THE 50S ACROSS THE LOWER ELEVATIONS WITH A FEW LOCATIONS NEAR THE VA BORDER MAY REACH 60 OR ABOVE ON A DOWN SLOPE COMPONENT. .LONG TERM...(FRIDAY NIGHT THROUGH WEDNESDAY) ISSUED AT 232 AM EST THU DEC 25 2014 CONFIDENCE IS HIGH THROUGH THE WEEKEND AS MODELS REMAIN IN GOOD AGREEMENT. THE PERIOD WILL START OFF DRY AS HIGH PRESSURE HOLDS INTO SATURDAY. FRIDAY NIGHT WILL FEATURE ANOTHER NIGHT OF GOOD RIDGE/VALLEY SPLITS...ESPECIALLY IN THE EAST. WE WILL THEN SEE A DECENT RECOVERY ON SATURDAY AS HIGHS SOAR TO AROUND 60 WITH THE HELP OF SUNSHINE. A SHORTWAVE TROUGH WILL PUSH INTO THE OHIO RIVER VALLEY LATE SATURDAY NIGHT INTO SUNDAY. THIS WILL BRING INCREASING CLOUDS LATE SATURDAY/SATURDAY NIGHT. RAIN WILL ALSO SPREAD INTO THE AREA SATURDAY NIGHT AND CONTINUE INTO SUNDAY. FORECAST BECOMES INCREASINGLY UNCERTAIN BEYOND SUNDAY AS THERE IS SOME QUESTION AS TO HOW LONG PRECIPITATION CHANCES LINGER. THE LATEST 00Z ECMWF HAS SPED UP THE SYSTEM WITH PRECIPITATION EXITING BY EARLY MONDAY MORNING. HOWEVER...12Z GFS CONTINUES TO HOLD PRECIPITATION OVER OUR SOUTHEAST COUNTIES INTO MONDAY NIGHT. FOR THIS REASON...WILL MAINTAIN SOME POPS IN THE FORECAST INTO MONDAY NIGHT. HOWEVER...THE HIGHEST POPS WILL BE CONFINED TO THE PART OF THE FORECAST WHERE THERE IS BETTER CONFIDENCE SATURDAY NIGHT AND SUNDAY. MODELS REMAIN TOO WARM TO SUPPORT ANYTHING BUT RAIN THROUGH MONDAY NIGHT. AFTER MONDAY NIGHT...MODELS HAVE COME INTO BETTER AGREEMENT ON A LESS ACTIVE PERIOD OF WEATHER. MID/UPPER LEVEL FLOW TURNS MORE ZONAL. EVEN THE IDEA OF A MID WEEK STORM PER THE LAST TWO RUNS OF THE ECMWF IS NOW MISSING ON THE LATEST RUN. THUS...GOING TO CUT BACK ON POPS THROUGH THURSDAY OF NEXT WEEK. IT DOES LOOK LIKE A SYSTEM MAY FINALLY TAKE SHAPE LATE THURSDAY INTO FRIDAY...BUT THIS IS JUST BEYOND THE CURRENT FORECAST PERIOD. THE TREND IS CERTAINLY TOWARDS QUIETER WEATHER NEXT WEEK...SO WILL HAVE TO SEE IF THE MODELS MAINTAIN THE SYSTEM FOR LATE IN THE WEEK. THE WEATHER SHOULD TREND TOWARDS NORMAL VALUES NEXT WEEK AS COOLER AIR SLOWLY WORKS INTO THE AREA AS PRECIPITATION ENDS MONDAY AND MONDAY NIGHT. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON) ISSUED AT 1246 PM EST THU DEC 25 2014 WIND FLOW AT THE SFC AND ALOFT CONTINUES TO BACK TO THE SOUTHWEST. LOW MVFR STRATOCU DECK WILL ONLY GRADUALLY DISSIPATE THROUGH THE FIRST 6 HOURS OR SO OF THE FORECAST. OTHERWISE WE FINALLY CLEAR OUT WITH LIGHT WINDS...GENERALLY FROM THE SOUTH...SOUTHWEST THROUGH THE REMAINDER OF THE FORECAST PERIOD. && .JKL WATCHES/WARNINGS/ADVISORIES...NONE. && $$ UPDATE...RAY SHORT TERM...JP LONG TERM...KAS AVIATION...RAY

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