Area Forecast Discussion
Issued by NWS Jackson, KY

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000 FXUS63 KJKL 251610 AFDJKL AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE JACKSON KY 1110 AM EST SUN JAN 25 2015 .UPDATE... ISSUED AT 1109 AM EST SUN JAN 25 2015 RECENT MODEL UPDATES CONTINUES TO BE MORE AND MORE CONSISTENT ON THE PROBABILITY OF MEASURABLE PRECIP ARRIVING THIS EVENING AND TONIGHT INTO TO MORROW MORNING WITH THE APPROACHING CLIPPER SYSTEM. AS SUCH...HAVE DECIDED TO UPDATE THE FORECAST AND PUT IN CATEGORICAL POPS INTO THE FORECAST...ALSO TO BETTER MATCH UP WITH NEIGHBORING OFFICES. AS WELL...ADJUSTED FOR TEMPERATURES THROUGH THE PERIOD. THE CHALLENGING PORTION OF THE TEMP RANGE WILL BE LATE TONIGHT AS TEMPS DROP WITH THE COLDER AIR ADVECTING INTO THE AREA BUT AS MORNING ARRIVES AND MINIMAL RADIATIONAL HEATING BEGINS FOR THE DAY...THE VALLEYS WILL HAVE A ROUGH TIME WARMING UP IF NOT REMAINING STEADY INTO THE AFTERNOON. HIGHER TERRAIN TEMPS WILL REMAIN STEADY OR DROP THROUGH THE MORNING AND INTO THE AFTERNOON TOMORROW. WITH THESE UPDATES...THE CHANGE OVER TO ALL SNOW IN SOME AREAS MAY BE A BIT EARLIER AND MAY CHANGE SNOWFALL TOTALS. WILL REEVALUATE WITH THE AFTERNOON UPDATES AND ARRIVAL OF THE 12Z MODEL RUNS BUT TOTALS LOOK MUCH THE SAME AT THIS POINT WITH A NEEDED HIGHLIGHT OF SPS FOR NOW. UPDATE ISSUED AT 648 AM EST SUN JAN 25 2015 IR SAT CONTINUES TO SHOW SOME HIGH CLOUDS SLOWLY PROGRESSING INTO EASTERN KY THIS MORNING. OTHERWISE TEMPS HAVE BEEN TRICKY WITH MANY VALLEY LOCATIONS ABLE TO DECOUPLE THIS MORNING LEADING TO 10 DEGREE SPLITS IN SOME CASES. FRESHENED UP GRIDS WITH LATEST OBS AND TRENDS WITH NO MAJOR CHANGES NEEDED THIS UPDATE. && .SHORT TERM...(TODAY THROUGH MONDAY) ISSUED AT 340 AM EST SUN JAN 25 2015 IR SATELLITE INDICATES HIGH TO MID LEVEL CLOUDS CONTINUING TO WORK INTO THE REGION THIS MORNING. THIS IS BEING PROVIDED BY NEXT SURFACE LOW PRESSURE AND SHORTWAVE DROPPING SOUTH OUT OF THE MIDWEST. CLOUDS HAVE BEEN SLOW TO PROGRESS INTO THE REGION AND HAS ALLOWED FOR SOME RIDGE/VALLEY SPLITS ACROSS PORTIONS OF THE REGION THIS MORNING. AFOREMENTIONED LOW PRESSURE IS FORECAST TO DIVE SOUTH AND BEGIN MOVING INTO PORTIONS OF EASTERN KY LATER THIS AFTERNOON. BEST CHANCES OF PRECIP WILL BE THIS EVENING INTO THE OVERNIGHT HOURS TONIGHT. GIVEN THAT LATEST RUNS SLOWED THIS SYSTEM A BIT OPTED TO LEAN THAT DIRECTION WHICH WILL MATCH BETTER WITH NEIGHBORING OFFICES. ALSO GIVEN DECENT WARM NOSE AHEAD OF THIS LOW DID UP MAX TEMPS TODAY A BIT WHICH ALSO MATCHES BETTER WITH SURROUNDING OFFICES AND THIS ALSO INTRODUCES A BIT WARMER TEMP CURVE INTO PORTIONS OF THIS EVENING. THIS LOW PRESSURE WILL CONTINUE TO MOVE SOUTH AND EAST ACROSS THE REGION...WHILE COLDER AIR WILL BEGINS TO FILTER INTO THE REGION OVERNIGHT INTO MONDAY. THIS WILL ALLOW MIXING OF RAIN AND SNOW TO BEGIN OCCURRING MAINLY AFTER MIDNIGHT AND EVENTUALLY THIS WILL CHANGE TO MOSTLY SNOW FOR MUCH OF THE AREA AS WE MOVE INTO MONDAY. THIS CHANGE OVER WILL OCCUR GENERALLY NORTH TO SOUTH OVERNIGHT INTO MONDAY. GIVEN THAT BETTER QPF DOES NOT COINCIDE WITH COLDER AIR THINKING ACCUMULATIONS WILL BE LIGHT AT THIS POINT. BEST ACCUMULATIONS WILL GENERALLY BE IN THE HIGHER TERRAIN 2000 FT AND ABOVE WHERE A INCH OR MORE COULD OCCUR. MOVING INTO MONDAY WOULD EXPECT MOST AREAS WILL BEGIN SEEING MORE UPSLOPE COMPONENT SNOW AS MAIN LOW WILL BE EAST ALONG THE EASTERN SEABOARD AS ENERGY TRANSFERS TO DEVELOPING NOREASTER. .LONG TERM...(MONDAY NIGHT THROUGH SATURDAY) ISSUED AT 425 AM EST SUN JAN 25 2015 THE MODELS ARE IN A BIT BETTER AGREEMENT THIS MORNING WITH THE LONGWAVE PATTERN AFFECTING THE NATION THROUGH THE EXTENDED PORTION OF THE FORECAST. THEY ALL DEPICT A DEEPENING CLOSED LOW DEVELOPING OFF THE MID ATLANTIC COAST ON TUESDAY WITH THE GFS MORE ROBUST THAN THE ECMWF. A STREAM OF ENERGY WILL FLOW NORTH NORTHWEST TO SOUTH SOUTHEAST INTO THIS TROUGH AND RIGHT OVER EAST KENTUCKY THROUGH WEDNESDAY MORNING. THE PATTERN BREAKS DOWN BY MIDDAY...THOUGH...AS BROAD RIDGING PUSHES INTO THE AREA FROM THE WEST BRINGING RISING HEIGHTS A NOTCH QUICKER IN FROM THE GFS AND GEM THAN THE ECMWF. THIS RIDGING WILL BE SHORT LIVED DUE TO A NASCENT TROUGH TAKING SHAPE OVER THE CENTRAL PLAINS ON THURSDAY. THIS TROUGH BECOMES STRONGEST IN THE ECMWF AS IT DIVES THROUGH THE MIDWEST AND INTO THE OHIO VALLEY LATER THURSDAY WHILE THE GFS AND GEM ARE COMPARATIVELY FAR WEAKER AND ILL-DEFINED. IN FACT...THE MID LEVEL TROUGH CLOSES OFF AS IT PASSES OVER EASTERN KENTUCKY FRIDAY MORNING ACCORDING TO THE ECMWF. EVEN TRAILING THIS ROBUST WAVE...THE ECMWF BRINGS A PACKET OF ENERGY THROUGH THE AREA BY SATURDAY MORNING WHILE ANOTHER STRONG...BUT SHALLOW...TROUGH WORKS THROUGH THE GREAT LAKES BY SATURDAY EVENING. MEANWHILE...A LARGE AND FAIRLY DEEP CLOSED LOW REIGNS OVER THE FAR SOUTHWEST...NEAR THE BAJA PENINSULA...FROM THURSDAY NIGHT INTO SUNDAY MORNING...MAINTAINING SPLIT FLOW IN BOTH THE GFS AND ECMWF. THIS IS A FAR CRY FROM THE BOLD PHASED STREAM FORECAST FOR THE SOUTHERN OHIO VALLEY THAT THE GFS WAS TEASING US WITH SEVERAL RUNS AGO. ANYWAYS... HAVE FAVORED A CONSENSUS FORECAST THROUGH WEDNESDAY BEFORE LEANING SLIGHTLY TOWARD THE MORE AMPLIFIED ECMWF. SENSIBLE WEATHER WILL FEATURE A DEEPENING COASTAL SYSTEM OFF THE MID ATLANTIC SEABOARD AT THE START OF THE EXTENDED WITH A MOISTURE TRAIL LEFT BEHIND OVER EASTERN KENTUCKY AND STRETCHED NORTHWEST TO A WEAK SFC LOW IN THE UPPER MIDWEST. THE DEEPENING OF THIS COASTAL AND ITS HUGGING OF THE COAST BY TUESDAY MORNING WILL LIKELY SUPPORT SOME UPSLOPE SNOW SHOWERS OVER EASTERN KENTUCKY THAT COULD LINGER FOR MUCH OF THE DAY AND INTO THE EARLY EVENING...THANKS ALSO TO THE SOME ADDED LAKE MOISTURE. FOLLOWING THIS...HIGH PRESSURE WILL BRING DRIER AIR TO THE STATE INTO WEDNESDAY NIGHT BEFORE ANOTHER SFC LOW CROSSES THE OHIO VALLEY ON THURSDAY INTO FRIDAY MORNING. THIS WILL MAKE FOR ANOTHER RAIN CHANGING TO SNOW SCENARIO FOR LATER THURSDAY THROUGH MIDDAY FRIDAY AS YET ANOTHER COASTAL LOW PUNISHES THE MID ATLANTIC AND COASTAL NEW ENGLAND STATES TO START THE WEEKEND. WHILE KENTUCKY WILL SEEMINGLY BE BETWEEN SYSTEMS FOR SATURDAY...A SURGE OF ARCTIC AIR IS LOOKING LIKE A BETTER BET FOR LATER THAT DAY AND INTO SUNDAY MORNING WHICH COULD RESULT IN SOME SNOW FOR THE AREA DESPITE LIMITED MOISTURE. AGAIN THIS IS QUITE DIFFERENT FROM THE VERY SNOWY SOLUTION FROM THE GFS A FEW RUNS AGO. THE CR GRID LOAD ONCE AGAIN MADE FOR A GOOD STARTING POINT FOR THE EXTENDED FORECAST WITH CHANGES MAINLY MADE TO BETTER REFLECT THE LINGERING SNOW CHANCES TUESDAY PER THE EXPECTED UPSLOPE FETCH. AGAIN...MADE SOME TYPICAL RIDGE AND VALLEY TEMPERATURE ADJUSTMENTS FOR LOWS EACH NIGHT. && .AVIATION...(FOR THE 12Z TAFS THROUGH 12Z MONDAY MORNING) ISSUED AT 631 AM EST SUN JAN 25 2015 SITES ARE VFR THIS MORNING AS IR SAT CONTINUES TO INDICATE MAINLY HIGHER CLOUDS MOVING ACROSS PORTIONS OF THE REGION THIS MORNING. MOST SITES THAT SAW SOME INDICATIONS OF LIGHT FOG HAVE COME UP OVERNIGHT TO P6SM...HOWEVER SOME VALLEY FOG CAN NOT BE RULED OUT THIS MORNING WITH MANY VALLEY LOCATIONS ABLE TO DECOUPLE AND THIS HAS BEEN ENHANCED BY PREVIOUS DAY SNOW. OTHERWISE FOCUS SHIFTS TO LOW PRESSURE AND UPPER LEVEL FEATURE DROPPING SOUTH ACROSS THE OHIO VALLEY LATER TODAY. THIS WILL BRING RAIN TO EASTERN KY LATE THIS AFTERNOON AND EVENING FROM NW TO SE. RIGHT NOW KEEPING SITES VFR LATE THIS AFTERNOON AND TRANSITIONING TO MVFR THIS EVENING. OVERNIGHT THIS PRECIP IS FORECAST TO BEGIN MIXING WITH AND CHANGING TO SNOW ACROSS PORTIONS OF THE REGION. THIS COULD BRING AFFECTED SITES DOWN TO IFR WITH LOWER CEILINGS AND VIS OVERNIGHT INTO EARLY MONDAY. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...SHALLENBERGER SHORT TERM...DJ LONG TERM...GREIF AVIATION...DJ

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