Area Forecast Discussion
Issued by NWS Jackson, KY

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000 FXUS63 KJKL 301912 AFDJKL AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE JACKSON KY 312 PM EDT THU JUL 30 2015 .SHORT TERM...(THIS EVENING THROUGH FRIDAY NIGHT) ISSUED AT 312 PM EDT THU JUL 30 2015 WEST NORTHWEST FLOW ALOFT IS IN PLACE ACROSS THE REGION BETWEEN A MID LEVEL RIDGE CENTERED OVER THE SOUTHERN PLAINS AND CLOSED LOW AND ASSOCIATED TROUGH CENTERED OVER THE HUDSON BAY REGION AND EXTENDING INTO THE GREAT LAKES AND NORTHEASTERN STATES. AT THE SFC...A COLD FRONT THAT CROSSED THE AREA LATE LAST NIGHT AND EARLY THIS MORNING...CONTINUES TO DEPART TO THE EAST OF THE REGION. A RIDGE OF SFC HIGH PRESSURE CONTINUES TO BUILD EAST INTO THE OH VALLEY REGION...AND IS USHERING DRIER AIR ON NW FLOW. DEWPOINTS ARE AS LOW AS THE UPPER 50S IN NORTHERN KY...WITH LOW TO MID 50S OVER PARTS OF INDIANA. THROUGH FRIDAY NIGHT...THE PATTERN IS EXPECTED TO AMPLIFIED. THE MID LEVEL RIDGE WILL RETROGRADE TO THE WEST AND BECOME CENTERED NEAR THE FOUR CORNERS REGION WITH RIDGING NORTH BUILDING NORTH ACROSS THE WESTERN CONUS. MEANWHILE...THE CLOSED LOW WILL MEANDER TO FAR NORTHERN ONTARIO THROUGH THE END OF THE PERIOD WITH THE AREA IN NW FLOW ALOFT BETWEEN THE RIDGE AND TROUGH...ALTHOUGH THE AXIS OF THE TROUGH SHOULD REMAIN GENERALLY EAST OF THE AREA. A FEW WEAK SHORTWAVES PASSING BY IN THE FLOW SHOULD BRING NOTHING MORE THAN A FEW CLOUDS FROM TIME TIME. A SFC LOW PRESSURE SYSTEM ASSOCIATED WITH ONE OF THESE SHORTWAVES SHOULD TRACK ACROSS ONTARIO AND INTO QUEBEC LATE IN THE PERIOD...WITH THE TRAILING MOISTURE STARVED COLD FRONT POSSIBLY DROPPING SOUTH OF THE GREAT LAKES LATE FRI NIGHT. WITH THE RIDGE BUILDING IN TONIGHT...COLDER OVERNIGHT LOWS...UP TO 10 DEGREES OR MORE COLDER THAN THIS AM ARE EXPECTED. DEWPOINTS MOVING INTO THE NORTH SUGGEST A FEW LOWS IN THE UPPER 50S FOR VALLEYS ALONG AND NORTH OF THE MTN PARKWAY. COOP MOS GUIDANCE ALSO SUPPORTS THOSE NUMBERS. THE LIGHT WINDS AND CLEAR SKIES SHOULD ALSO FAVOR SOME VALLEY FOG DEVELOPING ALONG A FEW OF THE LARGER CREEKS AND NEAR AREA RIVERS AND LAKES. FRIDAY SHOULD FEATURE HIGHS NEAR NORMAL FOR LATE JULY UNDER THE INFLUENCE OF HIGH PRESSURE...WITH MUCH MORE COMFORTABLE DEWPOINTS AND HUMIDITIES COMPARED TO RECENT DAYS. THE RIDGE SHOULD CONTINUE TO DOMINATE LATE IN THE PERIOD...ON FRIDAY NIGHT...WITH OVERNIGHT LOWS IN MOST LOCATIONS A DEGREE OR TWO WARMER TO TONIGHT. THE EXCEPTION TO THIS WILL BE THE FAR SOUTH AND SOUTHEAST VALLEYS...WHERE THE DRIER AIR WILL BE A TAD SLOWER TO MOVE IN...AND LOWS FRI NIGHT MAY BE A DEGREE OR TWO COLDER COMPARED TO TONIGHT. .LONG TERM...(SATURDAY THROUGH THURSDAY) ISSUED AT 246 PM EDT THU JUL 30 2015 FORECAST MODELS INDICATE THAT A TROUGH WILL REMAIN IN PLACE OVER THE EASTERN U.S. THROUGHOUT THE PERIOD. HIGH PRESSURE WILL REMAIN IN PLACE AT THE SURFACE OVER OUR AREA THROUGH MONDAY KEEPING OUR FORECAST DRY AND SEASONABLY WARM. A WEAK FRONT WILL DROP INTO THE OHIO VALLEY ON MONDAY. MODELS ARE QUITE DIFFERENT IN HOW THEY HANDLE THIS FRONT FROM TUESDAY THROUGH THE REST OF NEXT WEEK AND THIS LOWERS FORECASTER CONFIDENCE. WHILE THE GFS INDICATES A QUICK FRONTAL PASSAGE TUESDAY INTO TUESDAY NIGHT...FOLLOWED BY DRY WEATHER WEDNESDAY AND THURSDAY...THE GEM AND ECMWF INDICATE A STALLED FRONT TO OUR NORTH OR OVERHEAD WITH A BETTER CHANCE OF SHOWERS AND THUNDERSTORMS. A MODEL BLEND GIVES SLIGHT CHANCE TO CHANCE POPS TUESDAY THROUGH THURSDAY AND THAT SEEMS PRUDENT GIVEN THE MODEL DIFFERENCES. TEMPS SHOULD REMAIN NEAR SEASONAL NORMS NEXT WEEK WITH THE RIDGE ALOFT CENTERED WELL TO OUR WEST. && .AVIATION...(FOR THE 18Z TAFS THROUGH 18Z FRIDAY AFTERNOON) ISSUED AT 145 PM EDT THU JUL 30 2015 HIGH PRESSURE BUILDING INTO THE REGION WILL BRING MAINLY VFR THROUGH THE PERIOD. THE EXCEPTION WILL BE A BIT OF VALLEY FOG LATE TONIGHT. VFR FOG MAY AFFECT LOZ...SME...SJS AND SYM DURING THE 8Z TO 13Z WINDOW. HOWEVER...THE FOG COULD REDUCE VIS TO IFR... OR PERHAPS TO AIRPORT MINS AT SOME OF THE NON TAF LOCATIONS. ANY FOG SHOULD LIFT AND DISSIPATE AROUND 13Z...GIVING WAY TO VFR IN ALL LOCATIONS TO END THE PERIOD. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...JP LONG TERM...ABE AVIATION...HAL

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