Area Forecast Discussion
Issued by NWS Jackson, KY

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000 FXUS63 KJKL 271225 AAA AFDJKL AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE JACKSON KY 725 AM EST TUE JAN 27 2015 .UPDATE...
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ISSUED AT 725 AM EST TUE JAN 27 2015 A NEW SNOW BAND DEVELOPED OVER THE BLUEGRASS AREA AND HAS NOW SLIPPED SOUTHEAST INTO OUR CWA RIDING JUST A TAD NORTHEAST OF THE PREVIOUS ONE. ONLY BELATEDLY DID THE HRRR CATCH ON TO THIS LATEST BAND... THOUGH. ACCORDINGLY...HAVE UPDATED THE GRIDS TO REFLECT THE SNOW MOVEMENT AND ADJUSTED THE LIGHT SNOW AMOUNTS. ALSO FINE TUNED TEMPERATURES AND DEWPOINTS PER THE LATEST OBS AND TRENDS. THESE HAVE BEEN SENT TO THE NDFD AND WEB SERVERS.
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&& .SHORT TERM...(TODAY THROUGH WEDNESDAY) ISSUED AT 335 AM EST TUE JAN 27 2015 07Z SFC ANALYSIS SHOWS A DEEP AREA OF LOW PRESSURE OFF TO THE NORTHEAST WHILE LOCALLY THE PRESSURE GRADIENT IS RATHER RELAXED AND THIS IS LIMITING THE UPSLOPE COMPONENT OF THIS NIGHT/S SNOW THREAT. THE MAIN BANDS OF SNOW ARE BEING PRIMARILY DRIVEN BY A SFC TROUGH AXIS SPLITTING THE STATE AND A STREAM OF MID LEVEL ENERGY RUNNING NORTH NORTHWEST TO THE SOUTH SOUTHEAST OVER PARTS OF CENTRAL AND EASTERN KENTUCKY. ON RADAR...THIS BAND LINES UP WELL WITH THIS ENERGY STREAM AND IS ALSO ABLE TO TAP INTO EXTRA MOISTURE FROM LAKE MICHIGAN. THE SNOW ASSOCIATED WITH THIS HAS BEEN RELATIVELY LIGHT WITH MOST SITES REPORTING SNOW SEEING 4SM OR BETTER VIS...THOUGH IT IS LIKELY THAT UNDER THE HIGHEST RADAR RETURNS VIS IS LESS THAN 2 MILES. FOR THESE LOCATIONS...A COUPLE OF TENTHS OF AN INCH OR SO OF ACCUMULATION WILL BE POSSIBLE WHILE MOST OTHER PLACES WILL SEE JUST A THICK DUSTING OR LESS. AN SPS IS IN EFFECT FOR THIS AND IT WILL BE CONTINUED THROUGH DAWN AND THE MORNING RUSH HOUR FOR GOOD MEASURE. TEMPERATURES...MEANWHILE ARE IN THE MID TO UPPER 20S ACROSS THE AREA WITH DEWPOINTS A DEGREE OR SO LOWER AND WINDS LIGHT TO CALM. THE MODELS ARE IN GOOD AGREEMENT ALOFT THROUGH THE SHORT TERM PORTION OF THE FORECAST AS A CLOSED LOW DEEPENS OFF THE NEW ENGLAND COAST AND A STREAM OF ENERGY FLOWS NNW TO SSE OVER KENTUCKY AND INTO THE BROADER EAST COAST TROUGH TODAY. THIS FLOW WILL BE NUDGED EAST BY A MODERATELY STRONG RIDGE IN THE SOUTHERN STREAM CROSSING THE SOUTHERN PLAINS LATER TONIGHT. THIS RIDGE WILL BE PUSHED SOUTH BY A DEVELOPING TROUGH COMING OUT OF THE CENTRAL ROCKIES AND MOVING INTO THE CENTRAL PLAINS LATER WEDNESDAY. GIVEN THE GOOD MODEL AGREEMENT HAVE FAVORED THE HIGHER RESOLUTION HRRR AND NAM12 THROUGH THE FIRST PART OF THE FORECAST AND A BLEND THEREAFTER. SENSIBLE WEATHER WILL FEATURE A BATCH OF EARLY MORNING SNOW SHOWERS TARGETING MAINLY THE CUMBERLAND VALLEY OF EASTERN KENTUCKY. A FEW FLURRIES WILL THEN LINGER INTO EARLY AFTERNOON FOR FAR SOUTHEAST PARTS OF THE CWA BEFORE ALSO COMING TO AN END BY EARLY EVENING AS THE CLOUDS ATTEMPT TO CLEAR. THIS...ALONG WITH SOME CONTINUED CAA FROM THE EAST COAST STORM...WILL MAKE FOR A CHILLY NIGHT WITH LOWS IN THE TEENS FOR WEDNESDAY MORNING. DESPITE HIGH PRESSURE PASSING THROUGH... A BATCH OF LOW CLOUDS COULD DEVELOP OVERNIGHT AND HUG OUR EASTERN ZONES INTO DAWN WEDNESDAY...WHICH MAY SPARE THESE AREAS THE COLDEST TEMPS. THIS LOW LEVEL MOISTURE WILL ALSO NEED TO BE WATCHED FOR A POTENTIAL OF SPOTTY FREEZING DRIZZLE IF THE STRATUS GETS THICK ENOUGH. FOR NOW...THOUGH...IT LOOKS LIKE THIS WILL NOT BE THE CASE...BUT THE POTENTIAL IS THERE. OTHERWISE...THE APPROACH OF ANOTHER NORTHERN PASSING SFC LOW WILL HELP TO WARM THE AREA UP ON WEDNESDAY WITH TEMPS REBOUNDING INTO THE MID 30S NORTHEAST TO THE LOWER 40S SOUTHWEST. HOWEVER...HIGH CLOUDS WILL START TO MOVE IN BY AFTERNOON FROM THE NORTHWEST LIMITING SUNSHINE ONCE ANY LOW CLOUDS BREAK UP. USED THE BCCONSSHORT AS A STARTING POINT FOR TEMPERATURES... DEWPOINTS...AND WINDS THROUGH THIS AFTERNOON BEFORE PLUGGING IN THE SUPERBLEND THEREAFTER. DID MAKE SOME MINOR...TERRAIN BASED... ADJUSTMENTS TO HOURLY AND MINIMUM TEMPERATURES TONIGHT. AS FOR POPS...ENDED UP CLOSE TO A COMBINATION OF THE WETTER MAV AND DRIER MET TODAY WHILE AGREED WITH THE LOW POPS FROM ALL GUIDANCE TONIGHT AND WEDNESDAY ACROSS EAST KENTUCKY. .LONG TERM...(WEDNESDAY NIGHT THROUGH MONDAY) ISSUED AT 419 AM EST TUE JAN 27 2015 THE PERIOD BEGINS WITH HIGH PRESSURE CENTERED TO THE NORTH AND EAST WITH SOME WEAK UPPER LEVEL RIDGING ACROSS THE REGION. EYES TURN QUICKLY TO APPROACHING SURFACE LOW ACROSS THE MIDWEST THAT IS FORECAST TO PROGRESS EAST INTO THE GREAT LAKES. A COLD FRONT EXTENDING SOUTH FROM THE LOW WILL BE THE DRIVER FOR CHANCES OF PRECIP AS WE MOVE INTO THURSDAY MORNING INTO THURSDAY NIGHT. THEREFORE WEDNESDAY NIGHT WILL BE MET WITH INCREASING CLOUDS AND CHANCES OF PRECIP INCREASING AS WE MOVE TOWARD DAYLIGHT ON THURSDAY. THE PRECIP WILL BRING A CHANCES OF SNOW OR RAIN/SNOW MIX THURSDAY MORNING BEFORE CHANGING TO ALL RAIN LATE MORNING INTO THURSDAY AS WARMER AIR MAKES ITS WAY INTO THE REGION. THIS IS ALSO EVIDENT IN THE SOUNDS AS DRYER AIR IS SEEN IN THE UPPER LEVEL LEADING TO LESS ICE BY THURSDAY AFTERNOON. OTHERWISE THIS LOW PRESSURE SYSTEM AND ASSOCIATED SHORTWAVE WILL MOVE EAST THURSDAY NIGHT WITH LOW DEEPENING ACROSS THE NORTHEAST US. HERE WE SWITCH TO WEST TO NORTHWEST FLOW AND THEREFORE HAVE KEPT SOME POPS ACROSS EAST AND SOUTHEAST THURSDAY NIGHT INTO EARLY FRIDAY. THIS WILL LIKELY MIX WITH OR CHANGE TO SNOW AS WE MOVE THROUGH THE NIGHT. GIVEN LIMITED MOISTURE AT THIS POINT WOULD THINK LITTLE TO ANY ACCUMULATIONS WOULD BE EXPECTED WITH BEST CHANCES ACROSS THE HIGHER TERRAIN. MOVING INTO FRIDAY EXPECT DECREASING CLOUDS AND HIGH PRESSURE TO DROP SOUTH OUT OF THE UPPER PLAINS. THIS WILL USHER IN GENERALLY BELOW NORMAL TEMPS FOR FRIDAY. THE QUESTION REMAINS FRIDAY NIGHT AS TO HOW MUCH THE TEMPS BOTTOM OUT. RIGHT NOW WOULD SEEM LIKE BEST CHANCES FOR DECOUPLING WOULD BE ACROSS THE NORTH AND FAR EASTERN PORTIONS OF THE CWA. DID INTRODUCE SOME TEENS TO BETTER MATCH NEIGHBORING OFFICES. AFTER THIS THE HIGH PRESSURE MOVES EAST WITH RETURN FLOW SATURDAY WITH TEMPERATURES GENERALLY ABLE TO REBOUND INTO THE UPPER 30S TO LOWER 40S. THEN FOCUS SHIFTS TO NEXT SYSTEM DEVELOPING ACROSS THE SOUTHWEST US AND PLAINS STATES. THIS LOW PRESSURE WILL EVENTUALLY GET PICK UP BY NORTHERN STREAM SHORTWAVE AND PROGRESS EAST INTO THE MISSISSIPPI RIVER VALLEY LATE SATURDAY NIGHT. WE DO INTRODUCE SLIGHT TO CHANCE POPS SATURDAY NIGHT WITH SOME OF THIS MIXING WITH SNOW AND RAIN BEFORE CHANGING TO ALL RAIN SUNDAY AS LOW PRESSURE DEEPENS ALONG AND NEAR THE OHIO RIVER VALLEY THROUGH THE DAY SUNDAY. THIS RAIN WILL ONCE AGAIN TRANSITION TO MIX AND SNOW SUNDAY EVENING AND SUNDAY NIGHT FROM NORTH TO SOUTH AS COLDER AIR FILTERS INTO THE REGION BEHIND THIS LOW. GIVEN THE MORE NORTHERN TRACK OF THIS SURFACE LOW AND BEST QPF AHEAD OF COLDER AIR WOULD THINK THAT ACCUMULATIONS WOULD BE LIGHT IN TERMS OF ANY SNOW WE ARE ABLE TO GET. KEEP IN MIND THIS IS STILL IN THE FARTHER REACHES OF THE LONG TERM FORECAST AND WILL HAVE TO BE FINE TUNED AS WE GET CLOSER TO THE EVENT. AFTER THIS SYSTEM MOVES EAST WITH SOME NW FLOW SNOW SHOWERS CONTINUING ACROSS THE EAST AND SOUTHEAST. OTHERWISE COLDER AIR CONTINUES TO FILTER INTO THE REGION WITH TEMPERATURES STRUGGLING TO MAKE IT ABOVE FREEZING MONDAY. && .AVIATION...
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(FOR THE 12Z TAFS THROUGH 12Z WEDNESDAY MORNING) ISSUED AT 705 AM EST TUE JAN 27 2015 A STREAM OF SHORTWAVE ENERGY ALOFT WILL KEEP THE CHANCES OF SNOW IN THE FORECAST THROUGH MID MORNING FOR MUCH OF EASTERN KENTUCKY. THE EARLIER BANDS OF LIGHT SNOW SET UP MAINLY OVER THE SOUTHWEST PORTION OF THE FORECAST AREA...BUT THE NEXT BATCH...AND LIKELY LAST ONE... LOOKS TO PASS THROUGH THE AREA MORE TO THE NORTHEAST OF THE EARLIER ONES WITH A BETTER CHANCE OF AFFECTING THE JKL/SYM/SJS TAF SITES. HAVE UPDATED THESE WITH A TEMPO FOR SOME MVFR AND IFR CIGS AND MVFR VIS WITH ANY SNOW SHOWERS THROUGH MID MORNING. THE REST OF THE AREA WILL SEE THEIR CURRENT IFR CIGS IMPROVE TO MVFR SHORTLY AND THEN VFR LIKELY BY 17Z. LOOKING AT THE TIME HEIGHT SERIES FOR TONIGHT DECIDED TO ADD SOME IFR STRATUS IN THE EASTERN TAF SITES IN THE PREDAWN HOURS. WINDS WILL GENERALLY BE LIGHT AND VARIABLE THROUGH THE PERIOD.
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&& .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...GREIF SHORT TERM...GREIF LONG TERM...DJ AVIATION...GREIF

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