Area Forecast Discussion
Issued by NWS Jackson, KY

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000 FXUS63 KJKL 020952 AFDJKL AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE JACKSON KY 452 AM EST MON MAR 2 2015 .SHORT TERM...(TODAY THROUGH TUESDAY) ISSUED AT 305 AM EST MON MAR 2 2015 AN AREA OF LIGHT RAIN SHOWERS WILL CONTINUE TO MOVE ACROSS THE AREA EARLY THIS MORNING ALONG AN EASTWARD ADVANCING COLD FRONT. THE FRONT IS EXPECTED TO MOVE FAIRLY SLOWLY...SO THE RAIN ACCOMPANYING IT IS FORECAST TO LAST THROUGH 11 OR 12Z THIS MORNING. AREAS OF FOG WILL CONTINUE BE AN ISSUE THROUGH EARLY THIS MORNING AS WELL. THE PRECIP AND FOG SHOULD BE GONE BY BETWEEN 12 AND 13Z. ONCE THE FRONT HAS MOVED OFF WELL TO OUR EAST...EASTERN KENTUCKY SHOULD REMAIN PRECIPITATION THROUGH LATE THIS EVENING. OUR NEXT ROUND OF ACTIVE WEATHER WILL BEGIN TO AFFECT THE AREA LATE MONDAY NIGHT INTO TUESDAY AS A WEAK IMPULSE THAT IS FORECAST TO MOVE OUT OF THE SOUTHERN PLAINS...PHASES WITH A LARGE SCALE UPPER TROUGH THAT IS EXPECTED TO MOVE OUT OF THE CENTRAL ROCKYS AND ACROSS THE NORTHERN PLAINS AND GREAT LAKES REGION. THE SOUTHERN SYSTEM WILL EVENTUALLY MORPH INTO A WARM FRONT AS IT BEGINS TO MERGE WITH THE NORTHERN SYSTEM. AS THIS BOUNDARY MOVES NORTH ACROSS CENTRAL AND EASTERN KENTUCKY...LIGHT RAIN IS EXPECTED TO BREAK OUT ALONG IT. AT THE ONSET OF THE EVENT...WARM MOIST AIR ALOFT WILL PUSH ACROSS AND NORTH OF THE FRONT...OVERRIDING COLD AIR AT THE SURFACE. FREEZING RAIN...SLEET...AND PERHAPS EVEN SOME SNOW WILL BE POSSIBLE AS THE RAIN FALLS INTO THE COLD AIR BELOW. THE GOOD NEWS IS THAT THE WARM FRONT SHOULD MOVE THROUGH THE AREA QUICKLY ENOUGH TO PREVENT ANY SIGNIFICANT ICE ACCUMULATIONS FROM OCCURRING. THE WARM FRONT IS THEN PROGGED TO STALL JUST TO OUR NORTH. AFTER THIS HAPPENS...A WAVE OF LOW PRESSURE WILL FORM ALONG THE BOUNDARY AND BEGIN PUSHING THE BOUNDARY EASTWARD. THIS WILL ALLOW COLD AIR FROM THE NORTHERN AND CENTRAL PLAINS TO ALSO BEGIN PUSHING EAST...TRANSFORMING THE BOUNDARY INTO A POTENT COLD FRONT. WIDESPREAD RAIN WILL ACCOMPANY THE COLD FRONT AS IT MOVES SLOWLY EAST ACROSS THE OHIO AND TENNESSEE VALLEYS. THE RAIN COULD BE HEAVY AT TIMES AND COULD LEAD TO FLOODING PROBLEMS ACROSS THE AREA. AREAS PARTICULARLY PRONE TO FLOODING WILL BE THE KENTUCKY...CUMBERLAND...AND BIG SANDY RIVER BASINS...WHOSE HEADWATER AREAS STILL HAVE A GOOD DEAL OF SNOW COVER IN PLACE. ENOUGH SNOW HAS ALREADY MELTED ACROSS EASTERN KENTUCKY TO CAUSE THE GROUND TO BE COMPLETELY SATURATED. ANY ADDITIONAL RAINFALL THAT OCCURS OVER THE NEXT FEW DAYS WILL RUNOFF ALMOST IMMEDIATELY INTO AREA CREEKS...STREAMS...AND RIVERS. THIS SITUATION WILL NEED TO MONITORED CLOSELY. TEMPERATURES DURING THE SHORT TERM WILL START OUT QUITE A BIT BELOW NORMAL...WITH TODAYS HIGHS EXPECTED TO TOP OUT IN THE LOW TO MID 40S ACROSS THE AREA. TONIGHTS TEMPERATURES WILL NOT COOL OFF NEARLY AS MUCH AS WE HAVE SEEN THE PAST SEVERAL NIGHTS...AS WINDS WILL EVENTUALLY SHIFT THE SOUTHEAST...LEADING TO DOWNSLOPE WARMING IN OUR EAST AND ALLOWING FOR WARM AIR ADVECTION AT THE SURFACE. THE MAIN PUSH OF WARM AIR IS EXPECTED TO TAKE PLACE DURING THE DAY ON TUESDAY...AS WINDS SHIFT TO THE SOUTH AND BEGIN ADVECTING WARM AIR DIRECTLY OFF THE GULF OF MEXICO INTO THE REGION. HIGHS ON TUESDAY COULD EASILY MAX OUT IN THE MID TO UPPER 50S AREA WIDE. .LONG TERM...(TUESDAY NIGHT THROUGH SUNDAY) ISSUED AT 430 AM EST MON MAR 2 2015 THE EXTENDED FORECAST PERIOD BEGINS ON TUESDAY NIGHT WITH A RATHER ACTIVE AND HIGH AMPLITUDE PATTERN IN PLACE. UNDERWAY AND ALREADY IMPACTING THE OH VALLEY AT THIS TIME FRAME IS AN ENLONGATED LONGWAVE TROUGH OVER THE CENTRAL CONUS WITH THE TROUGH AXIS EXTENDING SOUTHWEST INTO THE FOUR CORNERS REGION WHERE A CLOSED LOW LIES ENTRENCHED OVER THE BAJA REGION. DURING THIS TIME...A STRONG AN ACTIVE JET CORE EXTENDS FROM OVER THE SOUTHWEST TO THE GREAT LAKES REGION WITH THE HIGHEST SPEEDS WITH THE JET MAX OVER THE WESTERN GREAT LAKES OF 140 TO 160 KNOTS. HEADING INTO THE DAY ON WEDNESDAY...THE MENTIONED LOW OVER THE BAJA EJECTS INTO THE SOUTHERN PLAINS WHILE THE ENLONGATED TROUGH MOVES THROUGH THE CENTRAL CONUS. THE DEVELOPED LIFT AND DYNAMICS OVER THE MS VALLEY AND INTO THE OH VALLEY IS QUITE SUBSTANTIAL AT THIS TIME AS THE MID AND UPPER LEVEL FLOW TAKE A SOUTHWEST TO NORTHEAST TRAJECTORY. THIS SETS THE STAGE FOR PRETTY EFFICIENT RAINFALL AT ONSET OF THE FIRST SYSTEM INTO TUESDAY NIGHT AND THROUGH THE DAY ON WEDNESDAY AND THEN ANOTHER POSSIBLE WINTER STORM LIKE EVENT INTO MID WEEK. THIS UNFORTUNATELY EXACERBATES THE CONCERN FOR FLOODING IN CONJUNCTION WITH THE SNOWMELT AND POSSIBLY EVEN MORE SNOW ON TOP OF THAT. CONCERNING THE LOWER LEVELS...HIGH PRESSURE CENTERED JUST OFF SHORE IN THE ATLANTIC NUDGING INTO THE SOUTHERN PORTIONS OF THE SOUTHEASTERN CONUS THROUGH THE MID WEEK WILL KEEP A NEARLY STALLED SOUTHWEST TO NORTHEAST ORIENTATION OF A SURPRISINGLY STRONG GRADIENT SURFACE COLD FRONT. THE DEVELOPMENT OF SEVERAL WAVES IN THE MID LEVELS ALONG THIS FRONT TUESDAY NIGHT INTO WEDNESDAY AND THROUGH THURSDAY WILL KEEP A SIGNIFICANT QPF OVER THE AREA. THIS WILL ONCE AGAIN KEEP FLOODING A THREAT WITH THE AMOUNT OF PRECIP EXPECTED. AN ADDITIONAL SHOT OF MOISTURE CONTINUES AS THE LAST WAVE RIDES NORTHEAST ALONG THE FRONT AND THIS FEATURE FINALLY KICKS THE SURFACE LOW OUT TO SEA BY THURSDAY NIGHT. IT IS WORTH MENTIONING...THAT THIS PATTERN DOES NOT HAPPEN OFTEN...ESPECIALLY POSTFRONTAL HEAVY SNOWFALL DURING THE LAST HALF OF THE WINTER SEASON. HOWEVER...THERE DOES SEEM TO BE SOME CONSISTENCY IN THE MODELS AND NOW THE NAM AND SREF AS THIS EVENT HAS COME INTO THAT TIME PERIOD. ENSEMBLE MEANS SHOWN FROM WWD PRODUCTS ARE INDICATING MUCH MORE IN THE WAY OF SNOW AND HAVE AT LEAST COLLABORATED WITH WWD TO COME UP WITH SOME SLIGHTLY LOWER SNOW VALUES AND SNOWFALL FORECASTS ARE IN LINE WITH THOSE TRENDS OF COLLABORATION. ANOTHER HELPFUL INDICATOR OF AT LEAST THE BLOCKING NEEDED FOR THAT SOUTHWEST TO NORTHEAST ORIENTATION OF THE NEARLY STALLED FRONT IS THE ENSEMBLE MEAN OF THE NAO. A SHARP DROP IN VALUES FROM THE NAO PRODUCT ARE OCCURRING DURING THE TIME OF THIS SYSTEMS SET UP. WHILE NOT NECESSARILY A SHARP DROP INTO NEGATIVE VALUES...THIS INDICATION WOULD BE ENOUGH FOR SOME BLOCKING OVER THE ATLANTIC AND IS ENOUGH TO HAVE SOME CONFIDENCE IN THE QPF AND SNOWFALL VALUES DISPLAYED IN THE FORECAST. IT IS VERY POSSIBLE TO BE GOING STRAIGHT FROM A FLOOD CONCERN TO A SNOWFALL CONCERN IN A MATTER OF 24 HOURS. AS FOR SNOW RATIOS INTO WEDNESDAY NIGHT AND THURSDAY...THERE IS SOME CONCERN AT ONSET OF THIS SYSTEM THAT SOME WARM AIR ALOFT MAY CREATE SOME FREEZING PRECIP WHICH WOULD LOWER SNOW TOTALS A BIT. GIVEN ALL THIS...THE GRADIENT MOVING THROUGH WOULD ENSURE COLD ENOUGH SURFACE TEMPS AND THEREFORE HAVE GONE WITH A STRONG MENTION IN THE HWO. QPF VALUES WILL GO FROM 2 TO 2.50 INCHES AND SNOWFALL IN THE 6 TO 8 INCH RANGE. THE PATTERN GOES QUITE AFTER THURSDAY WITH SURFACE HIGH PRESSURE MOVING IN AND A NOTICEABLE LACK OF ARCTIC AIR THAT HAS USUALLY BEEN FOLLOWING THESE SYSTEMS THIS WINTER...THOUGH STILL BELOW NORMAL HIGHS FOR FRIDAY. SATURDAY HIGHS FINALLY GET BACK TO NEAR NORMAL. BY SUNDAY...ANOTHER WAVE DROPPING INTO THE SOUTHERN PLAINS ASSISTS IN SURFACE LOW DEVELOPMENT AND THIS FEATURE TRACK NORTH BRINGING ADDITIONAL POSSIBLE WINTER WEATHER TO FAR SOUTHEASTERN KENTUCKY. OBVIOUSLY...THIS SYSTEM IS WAY TOO FAR OUT TO PIN DOWN WINTER PRECIP IF ANY. BUT IT DOES CONTINUE TO HIGHLIGHT AN ACTIVE AND WET PATTERN THROUGH THE EXTENDED. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z MONDAY NIGHT) ISSUED AT 1230 AM EST MON MAR 2 2015 NEAR LIFR CIGS WILL CONTINUE AS RAIN SHOWERS PUSH SOUTH ACROSS EASTERN KENTUCKY OVERNIGHT. THIS WILL ESSENTIALLY PUT CIGS AT OR BELOW AIRPORT MINIMUMS THROUGH MUCH OF THE NIGHT WITH LITTLE IMPROVEMENT EXPECTED. VISIBILITIES WILL ALSO BE SHARPLY REDUCED AT TIMES DUE TO THE PRECIPITATION AND SOME FOG THAT HAS BEGUN TO FORM ACROSS THE AREA...MEANING THERE WILL ALSO BE A GOOD CHANCE THAT VSBYS WILL FALL BELOW AIRPORT MINIMUMS AT TIMES. CIGS SHOULD BREAK UP AND LIFT TOMORROW MORNING AS THE FRONTAL BOUNDARY SHIFTS SOUTH OF THE AREA. THIS WILL ALLOW FOR A RETURN TO VFR CONDITIONS BY MIDDAY TOMORROW. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...AR LONG TERM...SHALLENBERGER AVIATION...AR

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