Area Forecast Discussion
Issued by NWS Jackson, KY

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000 FXUS63 KJKL 280050 AAA AFDJKL AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE JACKSON KY 750 PM EST SAT DEC 27 2014 .UPDATE... ISSUED AT 750 PM EST SAT DEC 27 2014 23Z SFC ANALYSIS SHOWS AN AREA OF LOW PRESSURE PUSHING INTO EASTERN KENTUCKY FROM THE SOUTHWEST. THIS HAS BROUGHT AN EARLY ROUND OF SHOWERS TO THE CUMBERLAND VALLEY. THESE HAVE BEEN BATTLING THE DRY AIR IN PLACE THROUGH THE AREA...BUT HAVE BEEN ABLE TO REACH THE GROUND WITH THE HEAVIER RETURNS. THESE SHOWERS WILL CONTINUE TO MOISTEN UP THE LOWER ATMOSPHERE THIS EVENING WITH THE NEXT SURGE AFTER MIDNIGHT LIKELY TO BRING WIDESPREAD RAIN TO THE ENTIRE CWA. WITH DEWPOINTS IN THE 40S...ONCE THE RAIN MOVES IN PROPERLY...LOW TEMPERATURES WILL BE CAPPED IN THE LOW TO MIDDLE 40S. HAVE UPDATED THE FORECAST TO FINE TUNE THE POP CHANCES AND INFUSE SOME OF THE LATEST NEAR TERM GUIDANCE INTO THE T AND TD GRIDS. THESE UPDATES HAVE BEEN SENT TO NDFD AND THE WEB SERVERS. A ZFP UPDATE WILL FOLLOW LATER THIS EVENING ONCE THE WIDESPREAD RAINS ARE ON OUR DOORSTEP. && .SHORT TERM...(THIS EVENING THROUGH SUNDAY NIGHT) ISSUED AT 331 PM EST SAT DEC 27 2014 CURRENT CONDITIONS ACROSS THE REGION FEATURE SURFACE LOW PRESSURE STRENGTHENING AS IT MOVES NORTHEAST INTO THE GREAT LAKES REGION. MEANWHILE...A SURFACE COLD FRONT ASSOCIATED WITH THIS LOW AS OF 20Z IS PUSHING INTO WESTERN KENTUCKY WITH A SWATH OF RAIN MOVING UP FROM THE MID MS RIVER VALLEY INTO CENTRAL KENTUCKY. WIDESPREAD CLOUD COVER AND RAIN CONTINUES TO PUSH EAST BUT SURFACE HIGH PRESSURE CENTERED JUST OFF THE NC COAST IS RETREATING SLIGHTLY SLOWER THAN ANTICIPATED. HENCE SOME BREAKS IN CLOUD COVER STILL ARE PRESENT IN EASTERN KENTUCKY. THIS WILL KEEP PRECIP OUT OF THE AREA A TAD LONGER...BUT AN NEW DEVELOPING SURFACE LOW PRESSURE ALONG THE WESTERN GULF COAST AND STRENGTHENING LOW LEVEL JET WILL REINFORCE THE MOISTURE SURGE NORTHEASTWARD INTO THE TN VALLEY AND OH VALLEY BY TONIGHT AND ESPECIALLY SUNDAY. MODELS SUPPORT THIS TREND AND AS SUCH...AM QUITE CONFIDENT THAT MEASURABLE PRECIP WILL MATERIALIZE TONIGHT AND HAVE GONE WITH CATEGORICAL POPS. THE STUBBORN RIDGE OVER THE BAHAMAS REMAINS IN PLACE THROUGH THE REST OF THE WEEKEND BEFORE WEAKENING LATE MONDAY AS THE TROUGH OVER THE EASTERN CONUS LIFTS INTO THE NEW ENGLAND STATES. THROUGH THIS PERIOD THOUGH...QUITE A STRONG MOIST LOW LEVEL SOUTHWEST FLOW WILL KEEP RAIN OVER EASTERN KENTUCKY THROUGH MONDAY MORNING BEFORE ENDING FROM NORTHWEST TO SOUTHEAST ON MONDAY NIGHT. LOW LEVEL MOISTURE MAY BE SLOW ENOUGH TO EXIT BEHIND THE FRONT THAT COLDER AIR MOVING IN MAY ALLOW FOR SOME BRIEF INSTANCES OF SNOW MIXING WITH THE RAIN OR CHANGING TO ALL SNOW IN THE NORTHWEST BLUEGRASS COUNTIES AND THE HIGHER TERRAIN IN THE COUNTIES BORDERING VIRGINIA. ANY INSTANCES THAT DO OCCUR ARE EXPECTED TO BE BRIEF AND NO ACCUMULATION IS EXPECTED. OVERALL...A WET AND RAINY END TO THE WEEKEND AND BEGINNING TO THE NEW WEEK IS ON TAP. .LONG TERM...(MONDAY THROUGH SATURDAY) ISSUED AT 358 PM EST SAT DEC 27 2014 A COLD FRONT...AND WEAK WAVES OF LOW PRESSURE MOVING ALONG IT...WILL BE EXITING THE AREA TO BEGIN THE EXTENDED PERIOD ON MONDAY. BASED ON THE LATEST MODEL TIME HEIGHTS AND SOUNDINGS...WEAK UPSLOPE FLOW AND RESIDUAL MOISTURE BEHIND THE DEPARTING BOUNDARY MAY ALLOW ISOLATED TO SCATTERED RAIN AND SNOW SHOWERS TO LINGER BEHIND THE FRONT. BASED ON MOISTURE AVAILABILITY AND THE LACK OF ICE CRYSTAL GROWTH ALOFT...PRECIPITATION SHOULD INITIALLY BE IN THE FORM OF RAIN SHOWERS THROUGH AROUND 12Z ON MONDAY. AFTER THAT...ENOUGH COLD AIR SHOULD SPILL INTO THE REGION TO ALLOW SOME SNOW FLURRIES TO MIX WITH SPRINKLES OR LIGHT RAIN SHOWERS MONDAY NIGHT THROUGH EARLY TUESDAY MORNING. THE NAM12 SOUNDINGS SEEMED TO HAVE THE BEST HANDLE ON THE TRANSITION BETWEEN PRECIP TYPES...SO THAT MODEL WAS USED TO CREATE THE POPS AND PRECIP TYPES THROUGH EARLY TUESDAY MORNING. ONCE THE PRECIP EXITS THE AREA TUESDAY MORNING...A RIDGE OF HIGH PRESSURE WILL INFLUENCE THE REGIONS WEATHER THROUGH LATE THURSDAY MORNING. A FAIRLY POTENT AREA OF LOW PRESSURE IS THEN FORECAST TO FORM IN THE SOUTHERN JET STREAM OVER THE SOUTHERN ROCKY MOUNTAINS. AS THIS SYSTEM ADVANCES EASTWARD...THE MODELS HAVE IT TAPPING INTO AMPLE GULF OF MEXICO MOISTURE WEDNESDAY NIGHT AND THURSDAY. SHOULD THE MODELS PAN OUT...THE FIRST PRECIP WOULD ENTER EASTERN KENTUCKY AROUND NOON ON THURSDAY AND GRADUALLY OVERSPREAD THE AREA FROM THERE. BY 2 OR 3Z FRIDAY...THE SYSTEM WILL TAP INTO SOME COLDER AIR...ALLOWING FOR PRECIP ALONG THE NORTHERN FRINGE OF THE PRECIPITATION SHIELD TO MIX WITH SNOW. THE PRECIP SHOULD TRANSITION TO ALL SNOW BY AROUND 6Z FRIDAY AS MORE COLD AIR SPILLS IN FROM THE NORTH. WARMER AIR IS THEN FORECAST TO PROGRESS NORTHWARD INTO THE AREA FRIDAY MORNING...ALLOWING PRECIP TO TRANSITION BACK TO A RAIN SNOW MIX AND THEN RAIN BY EARLY FRIDAY AFTERNOON. AT THIS TIME THERE IS TOO MUCH UNCERTAINTY AS TO THE EXACT TRACK OF THE SOUTHERN STREAM LOW AND THE AMOUNT OF COLD AIR THAT WILL BE AVAILABLE FOR THE TRANSITION TO SNOW. THEREFORE...HAVE ELECTED TO GO WITH ONLY MINIMAL SNOW ACCUMULATIONS THURSDAY NIGHT INTO FRIDAY MORNING. TEMPERATURES THROUGHOUT THE EXTENDED PERIOD LOOK TO BE WELL BELOW NORMAL BASED ON THE CURRENT MOS GUIDANCE. BASED ON THE LATEST MODEL SOUNDINGS...DECIDED TO CONTINUE WITH THIS OVERALL TREND UNTIL THE DATA SETTLES ON A SOLUTION. THE COLDEST DAYS UPCOMING LOOK TO BE TUESDAY THROUGH THURSDAY...AS COLD AIR INVADES BEHIND THE INITIAL FRONTAL BOUNDARY. DAYTIME HIGHS ON THOSE THREE DAYS MAY NOT RISE OUT OF THE 30S ACROSS THE AREA. FRIDAY SHOULD BE SLIGHTLY WARMER AS WINDS SHIFT TO THE SOUTH...WITH HIGH IN THE LOWER 40S ON TAP. && .AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SUNDAY EVENING) ISSUED AT 730 PM EST SAT DEC 27 2014 VFR CONDITIONS CURRENTLY AT MOST SITES WILL DEGRADE THROUGH THE EVENING FROM SOUTHWEST TO NORTHEAST. EXPECT CONDITIONS TO FALL TO MVFR WITH THE NEXT BATCH OF SOLID RAIN MOVING IN AND THEN FALL INTO THE IFR RANGE OVERNIGHT WHEN THE MOISTURE LADEN SYSTEM MOVES NORTHEAST OUT OF THE LOWER MS RIVER VALLEY. RAIN WILL SLOWLY DEVELOP ACROSS THE ENTIRE AREA THIS EVENING WITH CEILINGS DROPPING TO AIRFIELD MINIMUMS BY 12Z OVER MUCH OF THE FA...CONTINUING THROUGH THE END OF THE TAF PERIOD WITH JUST SOME MINIMAL IMPROVEMENTS DURING THE DAY SUNDAY. THE RAIN IS EXPECTED TO BE WIDESPREAD THROUGH THE BULK OF THE TAF PERIOD WITH LIGHT WINDS EXPECTED. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...GREIF SHORT TERM...SHALLENBERGER LONG TERM...AR AVIATION...GREIF

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