Area Forecast Discussion
Issued by NWS Jackson, KY

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000 FXUS63 KJKL 051820 AAA AFDJKL AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE JACKSON KY 220 PM EDT TUE MAY 5 2015 .UPDATE... ISSUED AT 1217 PM EDT TUE MAY 5 2015 FORECAST IS ON TRACK FOR TODAY SO ONLY MADE MINOR ADJUSTMENTS TO TEMP AND DEWPOINT GRIDS TO ALIGN THEM WITH RECENT OBS. SENT UPDATED GRIDS TO NDFD AND WEB SERVERS. UPDATE ISSUED AT 932 AM EDT TUE MAY 5 2015 QUICK UPDATE TO ALIGN T AND TD GRIDS WITH RECENT OBS. OTHERWISE...FORECAST REMAINS ON TRACK. SENT UPDATED GRIDS TO NDFD AND WEB SERVERS. UPDATE ISSUED AT 643 AM EDT TUE MAY 5 2015 WENT AHEAD AND REMOVED ANY MENTION OF FOG IN THE FORECAST GIVEN THE LACK OF EVIDENCE ON CURRENT OBS OR SATELLITE. IF ANY FOG IS IN THE VALLEYS IT SHOULD BE DISSIPATING IN THE NEXT HOUR AS THE SUN CONTINUES TO RISE ANYWAYS. ALSO TWEAKED TEMPERATURES WITH THE LATEST OBSERVATIONAL GUIDANCE TO MAKE SURE THEY WERE ON PAR WITH CURRENT CONDITIONS...WITH YET ANOTHER RAPID INCREASE INTO THE 70 DEGREE RANGE EXPECTED BY NOON OR JUST BEFORE. OTHERWISE FORECAST SEEMS TO BE WELL ON TRACK...WITH NO UPDATES TO THE CURRENT ZONE FORECAST NEEDED AT THIS TIME. && .SHORT TERM...
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(TODAY THROUGH WEDNESDAY) ISSUED AT 233 AM EDT TUE MAY 5 2015 STRONG HIGH PRESSURE/UPPER LEVEL RIDGING WILL STAY IN CONTROL THROUGH THE EXTENT OF THE SHORT TERM. LATEST FORECAST SOUNDINGS ARE STILL POINTING AT JUST ENOUGH MOISTURE TO ALLOW FOR SOME ISL/SCT AFTERNOON CU DEVELOPMENT BOTH TODAY AND WEDNESDAY...WITH BEST MOISTURE LIKELY DIRECTED OVER THE HIGH TERRAIN IN THE SE. DESPITE MODELS TRYING TO PUT PRECIP BACK IN ACROSS THIS SAME AREA ON WEDNESDAY...STILL BELIEVE DRY AIR NEAR THE SURFACE WILL WIN OUT AND SO KEPT POPS BELOW 15 PERCENT. OTHERWISE...LIGHT SRLY FLOW AND GOOD SUN COVERAGE WILL CONTINUE TO BOOST TEMPERATURES. EXPECT LOW TO MID 80S BOTH TODAY AND TOMORROW FOR HIGHS...WHILE OPTIMAL RADIATIONAL COOLING OVERNIGHT WILL CONTINUE TO PROMOTE LARGE RIDGE VALLEY SPLITS IN TEMPERATURE. THIS WILL RESULT IN SOME SIZABLE DIURNAL TEMPERATURE RANGES FOR VALLEYS BETWEEN MORNING LOWS AND DAYTIME HIGHS. .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 18Z TAFS THROUGH 18Z WEDNESDAY AFTERNOON) ISSUED AT 138 PM EDT TUE MAY 5 2015 EXPECT VFR CONDITIONS THROUGH THE PERIOD. INCLUDED DAYTIME CU DEVELOPMENT THROUGH THE AFTERNOON HOURS TODAY AND TOMORROW...WITH SKIES CLEARING DURING THE LATE EVENING HOURS. WINDS SHOULD GENERALLY BE LIGHT AND VARIABLE BELOW 5 KTS. WHILE AREAS OF VALLEY FOG ARE POSSIBLE LATE TONIGHT...DO NOT EXPECT TAF SITES TO BE AFFECTED. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...JVM SHORT TERM...JMW LONG TERM...GREIF AVIATION...JVM/JMW

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