Area Forecast Discussion
Issued by NWS Jackson, KY

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000 FXUS63 KJKL 060734 AFDJKL AREA FORECAST DISCUSSION NATIONAL WEATHER SERVICE JACKSON KY 334 AM EDT WED MAY 6 2015 .SHORT TERM...
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(TODAY THROUGH THURSDAY) ISSUED AT 334 AM EDT WED MAY 6 2015 WHILE HIGH PRESSURE WILL REMAIN THE DOMINANT FEATURE THROUGH THE SHORT TERM...THERE WILL LIKELY BE SOME MODIFICATION THAT WILL AFFECT THE PRECIPITATION FORECAST. FOR TODAY...EXPECT MUCH OF THE SAME AS YESTERDAY...WHERE A SLIGHT UPTICK IN MOISTURE WILL LEAD TO DAYTIME CU DEVELOPMENT ACROSS MUCH OF THE CWA...WHILE HIGH SUN ANGLES AND LIGHT WINDS WILL HELP BOOST TEMPS INTO THE MID AND EVEN POSSIBLY SOME UPPER 80S. BEST MOISTURE CONTINUES TO BE PINNED OVER THE FAR SE PORTION OF THE STATE...SO A FEW STRAY LIGHT SHOWERS DEVELOPING LATE IN THE AFTERNOON HERE ARE NOT OUT OF THE QUESTION. WENT AHEAD AND CONTINUED WITH MENTION OF ISL THUNDER IN FORECAST. OVERNIGHT WILL BE MUCH IN THE SAME AS WELL...WITH LOSS OF DAYTIME HEATING ALLOWING SKIES TO CLEAR OUT AND OPTIMAL RADIATIONAL COOLING TO OCCUR...ESPECIALLY IN THE VALLEYS. BY THURSDAY...HOWEVER...A SUBTROPICAL TROUGH TAKING SHAPE OFF THE SOUTH ATLANTIC WILL BEGIN FEEDING MOISTURE INLAND. WHILE HIGH PRESSURE RIDGING WILL REMAIN OVER KY...E TO SE WINDS WILL BRING ENOUGH MOISTURE OFF OF THE COAST TO ALLOW FOR A DEFINITE UPTICK IN HUMIDITY AND AFTERNOON CLOUD COVER. IT WILL ALSO MEAN A BETTER SHOT FOR AFTERNOON CONVECTIVE DEVELOPMENT...ESPECIALLY WITH TEMPS STILL EXPECTED TO BE IN THE MID AND UPPER 80S. UNFORTUNATELY...MODELS ARE HAVING A HARD TIME AGREEING ON JUST HOW MUCH MOISTURE WILL ACTUALLY MAKE IT TO THE SURFACE AS PRECIP. JUST LOOKING AT THE LATEST NAM MODEL SOUNDINGS...HI RES PLAN VIEW MODELS...AND THE DOWNSLOPING FLOW...STILL EXPECT MOST PRECIP WILL STAY OVER FAR SE KY...MAINLY ACROSS THE HIGHEST TERRAIN WITH SCT TO BKN CLOUD COVER ELSEWHERE. HOWEVER...SOME MODELS /THE GFS FOR INSTANCE/...ARE SPREADING WHAT SEEMS TO BE AN EXCESSIVE AMOUNT OF MOISTURE ACROSS THE ENTIRE EASTERN PORTION OF THE STATE. AS SUCH...TRIED TO MATCH UP WITH NEIGHBORING OFFICES BY FOCUSING MAIN AREA OF PRECIP ACROSS THE FAR SE CWA IN THE FORECAST...WITH ONLY A SLIGHT UPTICK IN POPS MAKING IT WESTWARD DURING THE PEAK HEATING OF MID AFTERNOON. ONCE THE SUN BEGINS TO FADE...EXPECT ANY TRIGGERING FEATURES WILL QUICKLY FADE AND ANY ONGOING RAIN/TSRA OR EVEN BKN CLOUD COVER WILL BREAK APART. .LONG TERM...(THURSDAY THROUGH TUESDAY) ISSUED AT 220 PM EDT TUE MAY 5 2015 THE MODELS ARE IN GOOD AGREEMENT ALOFT THROUGH THE BULK OF THE EXTENDED FORECAST. THEY ALL DEPICT A MODERATELY STRONG RIDGE DOMINATING THE EASTERN PORTION OF THE NATION WELL INTO THE WEEKEND. HOWEVER...THERE ALSO IS AN UNDERCUTTING WEAKNESS OFF THE SOUTHEAST COAST OF THE NATION AT MID LEVELS THAT COULD LEAD TO SOME INTERESTING WX THERE BY THE WEEKEND. THE DIRTY RIDGE WILL LIKELY NOT BE STRONG ENOUGH TO CAP ALL CONVECTION THROUGH EAST KENTUCKY AT PEAK HEATING EACH AFTERNOON...BUT CHANCES AT ANY ONE LOCATION WILL BE RATHER LOW. BETTER UPPER SUPPORT FOR CONVECTION WILL ARRIVE LATE IN THE WEEKEND AS THE RIDGE STARTS TO BREAK DOWN FROM THE NORTHWEST IN RESPONSE TO A TROUGH MOVING EAST INTO THE HIGH PLAINS WITH ROGUE BITS OF ENERGY BREAKING OFF AND RUNNING THROUGH THE OHIO VALLEY IN SOUTHWEST FLOW. THIS TROUGH WILL SLIP INTO THE MISSISSIPPI VALLEY REGION AND THE MIDWEST LATER MONDAY WITH HEIGHT FALLS IMPACTING KENTUCKY WHILE ADDITIONAL ENERGY TRACKS OVER THE AREA. THE TROUGH DOES MOVE MORE COMPLETELY INTO THE OHIO VALLEY AND GREAT LAKES ON TUESDAY WITH SOME SIGNIFICANT HEIGHT FALLS PROGGED...BY THE ECMWF IN PARTICULAR...TO AFFECT EAST KENTUCKY BY TUESDAY EVENING. A GENERAL MODEL BLEND IS ACCEPTED FOR THE BULK OF THE LONG TERM PORTION OF THE FORECAST GIVEN THE AGREEMENT EARLY ON AND AS A MEANS OF MITIGATING THE UNCERTAINTY HEADING INTO THE START OF NEXT WEEK. DID SIDE MORE WITH THE DRIER ECMWF FOR POPS EACH PERIOD. SENSIBLE WEATHER WILL FEATURE AN EARLY SUMMER-LIKE PATTERN BENEATH THE UPPER RIDGE AND A WEAK SFC HIGH. THERE WILL BE NO DRIVING FACTOR FOR CONVECTION THROUGH THE WEEKEND ASIDE FROM DIFFERENTIAL HEATING AND MINOR TERRAIN ENHANCEMENT. ACCORDINGLY...WITH RATHER DRY AIR IN PLACE BENEATH THE SFC HIGH...WILL KEEP ANY SMALL CHANCES FOR CONVECTION LIMITED TO THE HIGHER TERRAIN IN THE FAR SOUTHEAST AND ONLY AT OR JUST AFTER PEAK HEATING. EACH NIGHT SKIES SHOULD CLEAR FOLLOWING THE AFTERNOON/S DIURNALLY DRIVEN CU DEVELOPMENT WITH MILD RIDGE TOP TEMPERATURES AND COOLER VALLEYS. IN FACT...A MODERATE TO LARGE RIDGE TO VALLEY SPLIT IN THE TEMPERATURES IS EXPECTED EACH NIGHT IN THIS PATTERN...THROUGH THE WEEKEND. BY SUNDAY AFTERNOON... THE MID LEVEL ENERGY AND A SFC LOW MOVING INTO THE CENTRAL PLAINS MAY BE ENOUGH FOR CONVECTION TO MOVE INTO OUR WESTERN ZONES. MONDAY WILL ALSO SEE A POTENTIAL FOR DIURNALLY DRIVEN CONVECTION BY LATE AFTERNOON...BUT THE BEST CHANCES FOR MORE WIDESPREAD CONVECTION LOOKS TO HOLD OFF UNTIL TUESDAY WHEN THE SFC LOW MOVES INTO THE OHIO VALLEY AND ITS COLD FRONT CROSSES KENTUCKY. THE INCREASE IN CLOUDS AND BETTER PCPN CHANCES FOR THE START OF NEXT WEEK WILL ALSO RESULT IN COOLER TEMPS THAN WE WILL SEE FOR THE REST OF THIS WEEK AND INTO THE WEEKEND. THE CR GRID BLEND CAME IN ON THE WET SIDE FOR MOST PERIODS SO HAVE ADJUSTED THE POPS DOWN BASED MORE ON THE ECMWF AND THE DIURNAL CYCLE THROUGH MONDAY. DID ALSO MAKE SOME RATHER LARGE CHANGES TO LOWS EACH NIGHT GIVEN THE TERRAIN AND ANTICIPATED STRONG INVERSIONS. MONDAY NIGHT SHOULD SEE A MORE MIXED AIR MASS...ESPECIALLY IN THE WESTERN PARTS OF THE CWA.
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&& .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z WEDNESDAY NIGHT) ISSUED AT 152 AM EDT WED MAY 6 2015 HIGH PRESSURE AT THE SFC AND ALOFT SHOULD BRING VFR CONDITIONS THROUGH THE PERIOD. WINDS SHOULD GENERALLY BE LIGHT AND VARIABLE AND REMAIN BELOW 10 KTS. AREAS OF VALLEY FOG IN SOME RIVER VALLEY LOCATIONS ARE POSSIBLE LATE TONIGHT...BUT THE TAF SITES SHOULD NOT BE AFFECTED. CU DEVELOPMENT IN THE 5 TO 7K FT RANGE IS POSSIBLE ONCE MORE THIS AFTERNOON...WITH SOME ISOLATED LIGHT SHOWER CHANCES IN THE FAR SE PORTION OF THE STATE. EXPECT TAF SITES WILL REMAIN DRY. SKIES WILL CLEAR OUT ONCE MORE BY TOMORROW EVENING. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ SHORT TERM...JMW LONG TERM...GREIF AVIATION...JMW

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