Area Forecast Discussion
Issued by NWS Jackson, KY

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000 FXUS63 KJKL 311756 AFDJKL AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE JACKSON KY 1256 PM EST SAT JAN 31 2015 .UPDATE... ISSUED AT 1120 AM EST SAT JAN 31 2015 FRESHENED UP THE HOURLY TEMPERATURES...DEW POINTS...AND SKY COVER OVER THE NEXT FEW HOURS BASED ON THE CURRENT TRENDS IN OBSERVATIONS. OTHERWISE...THE FORECAST REMAINS ON TRACK. STILL WAITING ON THE NEWEST MODEL RUNS BEFORE ANY UPDATES ARE MADE CONCERNING THE PRECIP/WINTER WEATHER THAT IS INCOMING OVERNIGHT. OTHERWISE...CLOUDS ARE ON TRACK TO CONTINUE MOVING INTO THE REGION FROM THE WEST THROUGHOUT THE AFTERNOON. A FEW LIGHT RETURNS ARE ACTUALLY SHOWING UP ON NEIGHBORING RADARS WHERE BKN/OVC CLOUD COVER HAS TAKEN HOLD...BUT GIVEN THE AMOUNT OF LOW LEVEL DRY AIR...IT IS UNLIKELY THAT ANY OF THESE RETURNS WILL MAKE IT TO THE GROUND. DEW POINT DEPRESSION ARE STILL AROUND 8 OR MORE DEGREES IN THE AREAS WHERE THESE RETURNS ARE SHOWING UP. AS A RESULT...WILL NOT CHANGE POPS TO INCLUDE MENTION OF PRECIP AT THIS TIME UNLESS EVIDENCE STARTS TO SUPPORT OTHERWISE. UPDATE ISSUED AT 752 AM EST SAT JAN 31 2015 FRESHENED UP THE HOURLY TEMPERATURES...DEW POINTS...AND SKY COVER OVER THE NEXT FEW HOURS BASED ON THE CURRENT TRENDS IN OBSERVATIONS. OTHERWISE...THE FORECAST REMAINS ON TRACK. && .SHORT TERM...(TODAY THROUGH SUNDAY) ISSUED AT 359 AM EST SAT JAN 31 2015 SURFACE HIGH PRESSURE IS CURRENTLY SPRAWLED ACROSS THE MISSISSIPPI VALLEY...WITH DEEP LOW PRESSURE NEARING NOVA SCOTIA. ALOFT...A SPLIT FLOW REGIME IS CURRENTLY IN PLACE. A DEEP TROUGH IS POSITIONED IN THE WESTERN ATLANTIC...WITH NORTHWEST FLOW ALIGNED FROM THE OHIO VALLEY BACK TO THE CONTINENTAL DIVIDE WITHIN THE NORTHERN STREAM. IN THE SOUTHERN STREAM...RIDGING RESIDES ACROSS THE SOUTHERN PLAINS...WITH A CUTOFF LOW SPIRALING OVER THE DESERT SOUTHWEST. A COLD NIGHT IS ON TAP FOR EASTERN KENTUCKY WITH CLEAR SKIES AND CALM WINDS THANKS TO NEARBY HIGH PRESSURE. TEMPERATURES ARE CURRENTLY RUNNING AS COLD AS THE MIDDLE TEENS IN THE MORE SHELTERED VALLEYS...WITH RIDGETOPS AROUND 20. THE NORTHERN STREAM WILL CONTINUE TO BE THE DOMINANT PLAYER IN OUR WEATHER THROUGH THE SHORT TERM...AS A SHORT WAVE TROUGH CURRENTLY MOVING SOUTHEAST ACROSS ALBERTA WILL DROP SOUTHEAST AND DIG ACROSS THE PLAINS AND EVENTUALLY INTO THE OHIO VALLEY THROUGH THE END OF THE PERIOD. THIS WILL ALLOW FOR DEVELOPING SURFACE LOW PRESSURE TO MOVE EAST INTO THE LOWER OHIO VALLEY...BRINGING WIDESPREAD PRECIPITATION TO THE AREA BY LATE SUNDAY. TODAY WILL FEATURE A MOSTLY SUNNY START TO THE DAY...BEFORE MID AND HIGH LEVEL CLOUDS ARE ON THE INCREASE THIS AFTERNOON. DESPITE THE COLD START...TEMPERATURES SHOULD RECOVER TO THE 40S FOR MOST LOCATIONS. CLOUDS WILL CONTINUE TO THICKEN AND LOWER TONIGHT. AS ISENTROPIC LIFT ENSUES OUT AHEAD OF THE DEVELOPING LOW PRESSURE SYSTEM OFF TO THE WEST...SOME LIGHT PRECIPITATION IS POSSIBLE LATE TONIGHT INTO SUNDAY MORNING. THE GENERAL MODEL TREND HAS BEEN FOR A FURTHER NORTHWARD TRACK OF THE SURFACE LOW. A WARM NOSE AT AROUND 925 MB...RUNNING ANYWHERE FROM 4 TO 6C WILL ADVECT INTO THE AREA OVERNIGHT TONIGHT INTO EARLY SUNDAY MORNING. ANY LIGHT PRECIPITATION WILL START OUT AS A SNOW/SLEET MIXTURE...BEFORE LIKELY GOING OVER TO MAINLY LIQUID TOWARDS DAWN SUNDAY MORNING. AM A LITTLE CONCERNED THAT INTERIOR VALLEYS WILL LIKELY DECOUPLE SATURDAY EVENING...DROPPING OFF INTO THE MID AND UPPER 20S AND LIKELY NOT MODIFYING MUCH UNTIL THE MID TO LATE MORNING ON SUNDAY. AS SUCH...HAVE INCLUDED FREEZING RAIN AS A POSSIBILITY. ONCE THE SURFACE LOW DRAWS CLOSER DURING THE DAY...TEMPERATURES WILL WARM UP INTO THE 45 TO 50 DEGREE RANGE...WITH WIDESPREAD RAINS MOVING IN FROM WEST TO EAST SUNDAY AFTERNOON. .LONG TERM...(SUNDAY NIGHT THROUGH FRIDAY) ISSUED AT 359 AM EST SAT JAN 31 2015 THE EXTENDED FORECAST PERIOD BEGINS WITH AN ACTIVE AND PROGRESSIVE UPPER LEVEL PATTERN IN PLACE. SUNDAY NIGHT...A POTENT SHORTWAVE CONTINUES TO PROGRESS THROUGH THE OH VALLEY AND THE MID ATLANTIC STATES. MODELS CONTINUE TO SHOW NO ISSUES IN AGREEMENT WITH THE WAVE EXITING THE EAST COAST AS A 120 KNOT JET STREAK HEADING UP THE EAST COAST ALL THE TROUGH TO LIFT NORTHEAST INTO THE NORTHEAST AND EXIT OFF THE COAST BY TUESDAY 00Z. THE SURFACE LOW TRACK SEEMS TO BE SET TO MOVE ALONG AND JUST NORTH OF THE OH RIVER WITH A GOOD CONSENSUS OF THE MODELS SHOWING THIS NOW. FRONTAL PASSAGE SEEMS TO BE JUST AFTER 00Z MONDAY WITH COLD AIR ADVECTION THEN BEGINNING IN EARNEST AND A CHANGE OVER TO SNOW THROUGH THE NIGHT. HOWEVER...A GOOD PORTION OF THE DEPTH OF THE MOISTURE EXITS QUITE EARLY BEFORE THE COLDER AIR ARRIVES BEHIND THE FRONT. WITH THIS WOULD EXPECT A LESSER PERIOD OF SNOW BUT AN UPSLOPE COMPONENT TO THE WINDS WILL SET UP FOR THE DAY ON MONDAY. BECAUSE OF THIS...WOULD EXPECT SOME VERY LIGHT SNOW ACCUMULATIONS WITH THE MOST IN THE HIGHER ELEVATIONS. IN FACT...DESPITE THE SHALLOW MOISTURE...STILL SOME GOOD LIFT WILL REMAIN IN THE LOWER LEVELS WITH THE UPSLOPE FLOW THAT SNOW SHOWERS WILL LINGER INTO THE DAY ON MONDAY WITH LESS THAN AN INCH LIKELY IN THE VALLEYS BUT UP TO TWO INCHES POSSIBLE ABOVE 2000 FEET. IN A CONTINUED PROGRESSIVE UPPER LEVEL FLOW...A PASSING SHORT WAVE RIDGE WILL PROVIDE A DAYS BREAK FROM WEATHER BEFORE THE NEXT WAVE MOVES IN ON WEDNESDAY. HERE IS WHERE THE GFS AND EURO DIVERGE GREATLY. THE GFS BRINGS A DEVELOPING CLOSED LOW ACROSS THE SOUTH WITH THE AFOREMENTIONED WAVE MOVING INTO THE OH VALLEY ON WEDNESDAY AND CREATING A PHASING SCENARIO WITH THE POSSIBILITY OF HEAVY PRECIP OVER SOUTHEASTERN KENTUCKY AS A STRONG SURFACE LOW DEVELOPS ON THE LEE SIDE OF THE APPALACHIANS AND FINALLY MOVES EAST OFF THE COAST. BUT THE EURO KEEPS THE LOW TO THE SOUTH AND EXITS OFF THE SOUTHEASTERN COAST WHILE THE WAVE ALONG THE NORTHERN PORTION OF THE JET ONLY DRAGS A WEAK FRONT ACROSS THE AREA. THE MODEL ALL BLEND GOES BETWEEN THESE TWO SCENARIOS AND ONLY GIVES CHANCE POPS OVER THE AREA. THOUGH THE FRONT MOVING IN FROM THE NORTHWEST LOOKS PRETTY DRY...WILL LEAN TOWARDS THE MODEL ALL BLEND SOLUTION FOR CHANCE POPS ON WEDNESDAY THROUGH FRIDAY. THE TREND OF THE EURO AND GFS LEAVE LITTLE ROOM FOR CONFIDENCE DUE TO INCONSISTENCIES AND LACK OF AGREEMENT. WILL HAVE TO WATCH FOR TRENDS IN THE MODELS TO SEE IF THIS SET UP WILL POSE A THREAT. AS OF RIGHT NOW...THIS ONLY GETS A MENTION OF SNOW IN THE HWO. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON) ISSUED AT 1255 PM EST SAT JAN 31 2015 VFR CONDITIONS WILL HOLD ON THROUGH THE PERIOD...ALTHOUGH MID AND HIGH LEVEL CLOUDS WILL BE ON THE INCREASE THIS AFTERNOON AND EVENING OUT AHEAD OF THE NEXT APPROACHING WEATHER SYSTEM. CEILINGS WILL LOWER TO BETWEEN 5 AND 8K FEET AGL BETWEEN 06 AND 12Z AND CONTINUE INTO 18Z...WITH AT LEAST A SMALL THREAT OF SOME WINTRY PRECIPITATION. WINDS WILL AVERAGE LESS THAN 5 KTS. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...JMW SHORT TERM...GEOGERIAN LONG TERM...SHALLENBERGER AVIATION...JMW

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