Area Forecast Discussion
Issued by NWS Jackson, KY

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000 FXUS63 KJKL 260025 AAA AFDJKL AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE JACKSON KY 725 PM EST TUE NOV 25 2014 .UPDATE... ISSUED AT 725 PM EST TUE NOV 25 2014 DID AN UPDATED MAINLY TO FRESHEN UP THE T AND TD GRIDS PER THE LATEST OBS AND TRENDS. ALSO BUMPED UP THE SKY COVER QUICKER THROUGH THE EVENING AS HIGH CLOUDS HAVE SPREAD IN QUICKLY FROM THE SOUTHWEST. THE 18Z RUNS HAVE COME IN WITH BEEFIER THOUGHTS ON SNOW AS BOTH THE GFS AND NAM12 TAKE THE PCPN FURTHER WEST. THE GFS SEEMS TOO WARM AT THE SFC FOR MUCH SNOW OR ACCUMULATION FOR LOCATIONS OUTSIDE OF OUR CURRENT ADVISORY WITH ITS LATEST RUN. THE NAM12...ON THE OTHER HAND...APPEARS TO GO OVERBOARD ON THE QPF AND THEREFORE SNOW OVER OUR EASTERN COUNTIES. THERE REMAINS PLENTY OF FACTORS THAT WOULD HAMPER THIS OCCURRENCE WITH CONVECTION TO THE SOUTH CUTTING OFF SOME OF THE BEST MOISTURE FROM BEING TRANSPORTED INTO KENTUCKY AS CLEANLY AS ENVISIONED BY THE OFF SYNOPTIC TIME RUN. NEVERTHELESS WILL BE MONITORING THE RADAR TRENDS AND NEAR TERM MODELS FOR SIGNS THAT THE CURRENT FORECAST REMAINS ON TRACK. TO THAT THOUGHT...THE LATEST HRRR RUNS HAVE TRENDED ITS PCPN SHIELD FURTHER TO THE NORTHWEST BUT STILL A FAR CRY FROM THE 6 HOURLY MODELS. THE UPDATED GRIDS HAVE BEEN SENT TO THE NDFD AND WEB SERVERS. && .SHORT TERM...(THIS EVENING THROUGH WEDNESDAY NIGHT) ISSUED AT 325 PM EST TUE NOV 25 2014 ...ACCUMULATING SNOW EXPECTED OVER FAR EASTERN KENTUCKY TONIGHT INTO WEDNESDAY MORNING... 19Z SFC ANALYSIS SHOWS HIGH PRESSURE STILL INFLUENCING THE WEATHER OF EASTERN KENTUCKY. THIS HAS PROVIDED PLENTY OF SUNSHINE AND GENERALLY SOUTHWEST WINDS OF 5 TO 10 KTS WITH OCCASIONAL GUSTS TO 15 KTS. THESE CONDITIONS...ALONG WITH GOOD DRYING THROUGH EARLY AFTERNOON HAS SENT TEMPERATURES WELL UP INTO THE 50S FOR MOST OF THE AREA...THOUGH LOCATIONS NORTHWEST OF INTERSTATE 64 ARE LAGGING IN THE UPPER 40S. OF NOTE ON THE SFC CHART IS AN AREA OF DEVELOPING LOW PRESSURE CROSSING NORTHERN FLORIDA ON ITS WAY TO THE SOUTHEAST U.S. SEABOARD. THE MODELS ARE IN PRETTY GOOD AGREEMENT ALOFT THROUGH THE FIRST PART OF THE SHORT TERM FORECAST. THEY ALL TAKE A STRONG SHORTWAVE CURRENTLY BOTTOMING OUT OVER THE CENTRAL GULF COAST NORTHEAST INTO THE SOUTHERN APPALACHIANS BY WEDNESDAY MORNING. IN ADDITION...A COMPACT WAVE WILL BE DROPPING SOUTHEAST FROM THE NORTHERN PLAINS INTO THE MID MISSISSIPPI VALLEY AND EVENTUALLY THROUGH THE TENNESSEE VALLEY LATER WEDNESDAY NIGHT. THE MODELS ARE CLOSE ON THE TIMING OF THIS BUT THE CORE OF THE ENERGY IS FURTHER SOUTH IN THE NAM... ECMWF...AND GEM WHEN COMPARED TO THE GFS. WILL FAVOR THIS MORE SOUTHERN TRACK AS SEEN IN THE CONSENSUS. IN GENERAL HAVE LEANED MOST CLOSELY TO THE HIGHER RESOLUTION MODELS OF THE NAM12 AND HRRR... THOUGH THE HRRR PCPN FIELDS SEEM TOO FAR SOUTHEAST AND SLOW LATER TONIGHT. SENSIBLE WEATHER WILL FEATURE A QUICK INCREASE IN CLOUD COVER FROM THE SOUTHEAST AS THE COASTAL LOW STARTS TO TAKE SHAPE LATER THIS EVENING. LOWER CLOUDS AND PCPN WILL START TO SPILL OVER THE SPINE OF THE APPALACHIANS AND MOVE INTO OUR FAR EASTERN COUNTIES AROUND MIDNIGHT. EXPECT TEMPERATURES TO WET BULB DOWN WHEN THE PCPN MOVES IN AND TRANSITION THE RAIN TO SNOW IN THE HIGHER ELEVATIONS FIRST BUT EVENTUALLY DOWN IN THE VALLEYS...AS WELL. THE HEAVIEST SNOW WILL FALL IN THE HIGHER TERRAIN ALONG THE VIRGINIA BORDER WHERE AS MUCH AS A QUARTER TO A THIRD OF AN INCH OF LIQUID WILL LIKELY OCCUR. THIS WILL PROBABLY AMOUNT TO BETWEEN TWO AND THREE INCHES OF WET SNOW IN THE HIGHER TERRAIN...ABOVE 2000 FEET AND AROUND AN INCH OR LESS ELSEWHERE. HIGHER RIDGES BELOW 2000 FEET CAN EXPECT TO PICK UP BETWEEN ONE AND TWO INCHES BY MIDDAY WEDNESDAY. HAVE SET UP THIS AREA WITH A WINTER WEATHER ADVISORY FROM MIDNIGHT THROUGH NOON WEDNESDAY FOR THIS PASSING EVENT. WITH THE POTENTIAL FOR LIGHT ACCUMULATIONS IN THE COUNTIES IMMEDIATELY WEST OF THE ADVISORY WILL ALSO ISSUE AN SPS ADDRESSING THIS MARGINAL CONCERN. OTHERWISE...THE COASTAL PULLS OUT LATER WEDNESDAY WITH A BRIEF VISIT BY HIGH PRESSURE FOR EAST KENTUCKY IN ITS WAKE. HOWEVER...THE NEXT DEVELOPING LOW WORKS IN FROM THE NORTHWEST LATER THAT NIGHT CARVING ITS WAY THROUGH OUR SOUTHERN COUNTIES INTO DAWN THURSDAY. THIS TOO WILL BRING SOME RAIN OR SNOW TO PARTS OF THE AREA WITH SOME SLUSHY LIGHT SNOW ACCUMULATIONS POSSIBLE MAINLY ON RIDGES AND GRASSY/ELEVATED SURFACES. AGAIN USED THE BCCONSSHORT AS A STARTING POINT FOR T/TD/WINDS THROUGH THE NEXT 24 HOURS AND THE SUPERBLEND THEREAFTER. DID MAKE SOME MORE SIGNIFICANT TERRAIN BASED ADJUSTMENTS TONIGHT INTO WEDNESDAY IN THE EXPECTED SNOW AREAS OF THE FAR EAST. AS FOR POPS...ENDED UP CLOSE TO A BLEND OF THE MAV AND MET NUMBERS THROUGH THE PERIOD. .LONG TERM...(THURSDAY THROUGH TUESDAY) ISSUED AT 354 PM EST TUE NOV 25 2014 SHORTWAVE ENERGY ROUNDING THE BASE OF THE TROUGH AND ASSOCIATED LOW PRESSURE WILL BE MOVING EAST OF THE REGION WITH BEST POP CHANCES ACROSS THE SE PORTIONS OF THE CWA. THIS WILL GENERALLY BE LIGHT RAIN/SNOW SHOWERS AND DO NOT EXPECT MUCH QPF THROUGH THE DAY THURSDAY AT THIS POINT. THIS SYSTEM SLIDES EAST ALLOWING FOR NW/W FLOW TO SETUP ACROSS THE REGION AND THEREFORE HELD SLIGHT CHANCE IN FAR SE INTO THE AFTERNOON. SURFACE HIGH PRESSURE WILL SLOWLY SLIDE EAST THROUGH THE NIGHT THURSDAY AND GENERALLY CRESTING ACROSS THE REGION EARLY FRIDAY. THIS HIGH PRESSURE BUILDS EAST BRINGING RETURN SOUTHERLY FLOW TO EASTERN KY WITH TEMPERATURES RISING INTO THE LOWER 50S SATURDAY. SATURDAY AFTERNOON WE DO PRESENT SOME SLIGHT CHANCE SHOWERS ESPECIALLY ACROSS THE FAR NORTH AS FRONTAL BOUNDARY GENERALLY STALLS ACROSS THE NORTH. THIS QUASI-STATIONARY FRONT WILL KEEP THE WEATHER UNSETTLED THROUGH THE PERIOD. THE QUESTION REALLY BECOMES HOW QUICKLY DOES THIS BOUNDARY MOVE SOUTH...THAT SAID THE 12Z ECMWF IS MORE PROGRESSIVE MOVING THIS FRONT SOUTH THAN THE 12Z GFS. RIGHT NOW WITH MODEL DISCREPANCIES WILL KEEP BLEND POPS FOR THE MOST PART BUT WOULD THINK THESE POPS WILL CONTINUE TO TREND UP ONCE MODELS COME INTO BETTER ALIGNMENT. SATURDAY HIGHS ARE EXPECTED TO WARM INTO THE LOW TO MID 50S WITH TEMPERATURES MODIFYING INTO THE UPPER 50S TO LOWER 60S THROUGH THE PERIOD. && .AVIATION...(FOR THE 00Z TAFS THROUGH 00Z WEDNESDAY EVENING) ISSUED AT 700 PM EST TUE NOV 25 2014 VFR CONDITIONS WILL CONTINUE THROUGH THE REST OF THE EVENING THOUGH CIGS WILL TAKE SHAPE AND START TO LOWER DOWN TO 10K FEET BY MIDNIGHT. A DEVELOPING LOW PRESSURE SYSTEM WILL SPREAD MOISTURE AND LOWER CLOUDS OVER EASTERN KENTUCKY LATER TONIGHT...WITH CIGS FALLING INTO THE MVFR RANGE IN THE EAST BY 08Z. IT STILL LOOKS LIKE WE SHOULD SEE A GRADIENT IN THOSE LOWER CIGS WITH THE LOWEST (IFR/MVFR) IN THE EAST...TRAILING BACK TO VFR IN THE WEST...THROUGH MID MORNING WEDNESDAY. WE WILL ALSO SEE PRECIPITATION SPREAD INTO THE AREA... MAINLY ACROSS SOUTHEASTERN KENTUCKY...AS A MIX OF RAIN AND SNOW...LIKELY BECOMING ALL SNOW IN THE PRE-DAWN HOURS. THIS SNOW WILL RESTRICT VISIBILITIES LATER TONIGHT AS WELL...PARTICULARLY AT KSJS WHERE VIS COULD BE BELOW A MILE AT TIMES IN THE HEAVIER SNOW BANDS. THE SNOW AND ANY RESTRICTIONS WILL END FOR THE TAF SITES FROM SOUTHWEST TO NORTHEAST DURING THE MORNING WEDNESDAY. WINDS WILL BE LIGHT AND VARIABLE THROUGH THE PERIOD. && .JKL WATCHES/WARNINGS/ADVISORIES... WINTER WEATHER ADVISORY FROM MIDNIGHT TONIGHT TO NOON EST WEDNESDAY FOR KYZ087-088-110-113-115-117>120. && $$ UPDATE...GREIF SHORT TERM...GREIF LONG TERM...DJ AVIATION...GREIF

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