Area Forecast Discussion
Issued by NWS Jackson, KY

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210 FXUS63 KJKL 051953 AFDJKL AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE JACKSON KY 353 PM EDT THU MAY 5 2016 .SHORT TERM...(THIS EVENING THROUGH FRIDAY NIGHT) ISSUED AT 325 PM EDT THU MAY 5 2016 WV SAT AND HRRR HAS SUGGESTED THAT THE UPPER LEVEL CLOSED LOW HAS PROGRESSED SOUTHEAST INTO WESTERN NC AND NW SC. OVERALL THE MESO MODELS AND MORE SYNOPTIC MODELS HAVE HAD A DECENT HANDLE ON THIS PROGRESSION. WE CONTINUE TO HAVE SOME SHOWERS THAT HAVE DEVELOPED ACROSS THE SOUTH AND SW PORTIONS OF THE CWA. THIS HAS BEEN DUE TO THE STEEPER LOW LEVEL LAPSE RATES...AS WE HAVE SEEN BREAKS IN THE CLOUDS. THESE LAPSE RATES ARE COMBINING WITH THE ALREADY REASONABLY STEEP MID LEVEL LAPSE RATES. OVERALL COVERAGE HAS BEEN SCATTERED WITH BETTER COVERAGE TO THE SOUTH AND EAST. RIGHT NOW MODELS DO WANT TO BRING ADDITIONAL SHOWERS IN THE FAR EAST THIS EVENING AND TONIGHT...HOWEVER BIGGEST QUESTION WOULD BE HOW MUCH COVERAGE DO WE SEE. RIGHT NOW OPTED TO LOWER POPS GIVEN SOME OF THE UNCERTAINTY. THIS UNCERTAINTY COMES WHEN LOOKING UPSTREAM RADAR COVERAGE IS QUITE LOW COMPARED TO WHAT MAY HAVE BEEN PREVIOUSLY THOUGHT AND CAMS ARE NOT HITTING IT TOO HARD EITHER. THE OTHER QUESTION WOULD BE HOW MUCH CLOUD COVER DO WE SEE TONIGHT...RIGHT NOW KEEP CLOUD COVER HIGHER IN THE EAST GIVEN THE BETTER SHOWER COVERAGE. ALSO COULD HAVE IMPLICATIONS ON TEMPS AND FOG POTENTIAL. RIGHT NOW WILL ADD SOME PATCHY DEEPER VALLEY FOG AND JUST MINOR TEMP SPLIT GIVEN THE CLOUD UNCERTAINTY. THIS UPPER LOW IS FAIRLY SLOW TO MOVE EAST...AS A OMEGA BLOCK PATTERN SETS UP ACROSS THE CENTRAL PART OF THE CONUS. THEREFORE SURFACE HIGH PRESSURE WILL BE SLOW TO BUILD NORTHEAST FROM THE GULF. THAT SAID THERE WAS A NEED FOR SHOWERS IN THE FAR EAST AND SOUTHEAST FOR FRIDAY GIVEN THE SLOW PROGRESS OF VERTICALLY STACKED LOW AND CONTINUED PVA/SHORTWAVES DIVING SOUTH. NOW FRIDAY NIGHT HEIGHTS WILL CONTINUE TO RISE AS UPPER LOW/OMEGA BLOCK BREAK DOWN AND PROGRESS EAST. THERE IS A WEAK SURFACE TROUGH OR WAVE MAY BRING SOME SLIGHT CHANCE SHOWERS TO THE FAR NORTH OVERNIGHT. OTHERWISE MOST SPOTS SHOULD DRY OUT AT THIS POINT. .LONG TERM...(SATURDAY THROUGH THURSDAY) ISSUED AT 353 PM EDT THU MAY 5 2016 MODELS ARE IN REASONABLY GOOD AGREEMENT WITH AN OMEGA BLOCK PATTERN DEAMPLIFYING OVER THE WEEKEND AND EVOLVING TO MORE OR LESS A SPLIT FLOW PATTERN NEXT WEEK. THE CURRENT UPPER LEVEL SYSTEM MEANDERING OF THE APPALACHIANS AND THE SOUTHEAST IS EXPECTED TO SHIFT OFF THE EASTERN SEABOARD. AT THE SAME TIME...AN UPPER LEVEL LOW WILL MOVE FROM THE HUDSON AND JAMES BAY REGION INTO ONTARIO AND QUEBEC AND THEN INTO THE CANADIAN OVER THE WEEKEND AND INTO EARLY NEXT WEEK. A SHORTWAVE TROUGH IS EXPECTED TO MOVE THROUGH THE GREAT LAKES REGION EARLY IN THE PERIOD AND INTO THE NORTHEASTERN CONUS BY THE END OF THE WEEKEND. THIS WILL SEND A COLD FRONT INTO THE OHIO VALLEY AND APPALACHIAN REGION FROM LATE SATURDAY INTO SATURDAY NIGHT...WITH THE BOUNDARY STALLING OUT LATE IN THE WEEKEND ACROSS THE OHIO OR TENNESSEE VALLEY. THE MODEL CONSENSUS IS FOR A SMALL CHANCE OF CONVECTION ON ISENTROPIC LIFT EARLY IN THE PERIOD ON SATURDAY. A LULL IN ACTIVITY IS POSSIBLE FROM MIDDAY INTO THE AFTERNOON ON SATURDAY...WITH MORE ORGANIZED CONVECTION LIKELY SATURDAY EVENING INTO SATURDAY NIGHT. CHANCES FOR CONVECTION APPEAR TO LESSEN ON SUNDAY AS THE SHORTWAVE TROUGH DEPARTS TO THE EAST AND NORTHEAST. AN AREA OF SFC LOW PRESSURE MEANWHILE WILL BEGIN TO DEVELOP OVER THE WEEKEND IN THE LEE OF THE ROCKIES AHEAD OF THE SECOND UPPER LEVEL LOW MEANDERING FROM THE SOUTHWESTERN CONUS INTO THE ROCKIES OVER THE WEEKEND AND EVENTUALLY EJECTING INTO THE PLAINS. IN RESPONSE TO THE DEVELOPING LOW AND HEIGHT RISES OVER THE SOUTHEASTERN CONUS...THE STATIONARY FRONT SHOULD RETURN NORTH AS A WARM FRONT MONDAY INTO MONDAY NIGHT. EVEN AS THE REGION GETS INTO THE WARM SECTOR CONVECTION CANNOT BE RULED OUT AT ANY POINT ON MONDAY. THE SFC LOW PRESSURE SYSTEM SHOULD GRADUALLY TRACK FROM THE PLAINS TOWARD THE GREAT LAKES REGION AT MIDWEEK AND THEN EVENTUALLY INTO THE NORTHEASTERN CONUS. MODEL AGREEMENT FROM RUN TO RUN AND MODEL TO MODEL IN THESE DETAILS DIMINISHES GREATLY BY TUESDAY AND TUESDAY NIGHT AND ALSO CONFIDENCE IN ANY DETAILS. HOWEVER...THE OVERALL MODEL BLEND AND CONSENSUS APPEARS TO BE FOR ANOTHER PEAK IN CONVECTION CHANCES FROM LATE MONDAY NIGHT OR TUESDAY INTO THE DAY ON WEDNESDAY AS SEVERAL SHORTWAVES SHOULD MOVE THROUGH THE OHIO VALLEY AND GREAT LAKES REGION. LOCALLY HEAVY RAIN COULD BECOME A CONCERN IN LOCATIONS THAT EXPERIENCE MULTIPLE ROUNDS OF CONVECTION. TEMPERATURES SHOULD AVERAGE ABOVE NORMAL IN THE WARM SECTOR TO START THE PERIOD...ALTHOUGH TEMPERATURES SHOULD BE SUPPRESSED ON SUNDAY AND SUNDAY NIGHT WITH THE FRONT ACROSS THE AREA AND ABUNDANT CLOUD COVER ANTICIPATED. THEREAFTER...TEMPERATURES SHOULD AVERAGE A BIT ABOVE NORMAL THROUGH THE REST OF THE PERIOD...WITH HIGHS IN THE MID 70S TO AROUND 80 AND LOWS IN THE UPPER 50S TO AROUND 60. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON) ISSUED AT 130 PM EDT THU MAY 5 2016 CIGS ARE IN THE VFR TO MVFR RANGE TO BEGIN THE PERIOD...THE MVFR SITES HAVE BEEN IN FLUX. THAT SAID OVERALL SYNOPTICALLY WE ARE SEEING A UPPER LEVEL LOW TRACK RIGHT ACROSS THE AREA AND NOW IT HAS SHIFT SE INTO EASTERN TN THIS AFTERNOON. THE BREAKS IN THE CLOUD COVER HAVE LEAD TO A FEW SHOWERS ACROSS THE REGION MAINLY AT JKL...LOZ...AND SME. HOWEVER MORE SHOWERS ARE EXPECTED TO DEVELOP AND TRACK INTO THE FAR EAST AND NORTHEAST. OVERALL EXPECTING LOW VFR TO BE PREDOMINATE CIGS...BUT OCCASIONAL MVFR NOT OUT OF THE QUESTION WITH HEAVIER SHOWERS. THE CLOUDS TONIGHT WILL BE TRICKY AND UPSLOPE MAY HELP KEEP STRATO CU GOING...HOWEVER IF WE SEE GREATER REDUCTIONS FOG CONCERNS WOULD NEED TO BE EVALUATED PARTICULARLY IN THE VALLEY TAF SITES. OVERALL WINDS WILL REMAIN LIGHT...BUT SOME GUSTS WOULD BE POSSIBLE FRIDAY AFTERNOON MORE PAST THE TAF PERIOD. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...DJ LONG TERM...JP AVIATION...DJ

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