Area Forecast Discussion
Issued by NWS Jackson, KY

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000 FXUS63 KJKL 300536 AAC AFDJKL AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE JACKSON KY 136 AM EDT SAT AUG 30 2014 .UPDATE... ISSUED AT 125 AM EDT SAT AUG 30 2014 HOURLY GRIDS HAVE BEEN FRESHENED UP BASED ON RECENT SATELLITE AND RADAR TRENDS AS WELL AS FOR SFC OBSERVATIONS. THIS GENERALLY TRANSITIONED THE CHANCES FOR A STRAY SHOWER AND OR A THUNDERSTORM IN THE BIG SANDY REGION OUT TO THE NORTH NORTHEAST OVER THE NEXT HOUR OR SO. SOME LOW AND MID CLOUDS WILL LINGER IN BEHIND THIS AREA AS THE RATHER ILL DEFINED WARM FRONT LINGERS ACROSS THE REGION...BUT THESE ARE PROGGED TO THIN OVERNIGHT LEAVING BEHIND MAINLY CIRRUS. AS SKIES GRADUALLY CLEAR...VALLEY FOG SHOULD FORM IN SEVERAL AREAS...ESPECIALLY IN LOCATIONS THAT RECEIVED RAIN DURING THE LAST 12 HOURS. UPDATE ISSUED AT 955 PM EDT FRI AUG 29 2014 THE BEST LAID PLANS... IT LOOKS LIKE SOME OF THE CONVECTION MOVING NORTH FROM WESTERN VIRGINIA WILL SLIP INTO OUR CWA OVER THE NEXT HOUR OR TWO WITH ADDITIONAL SHOWERS OR A STRAY STORM POSSIBLE THROUGH THE EARLY MORNING HOURS PER TRENDS AND THE 00Z NAM12. THEREFORE...HAVE INTRODUCED THEM INTO THE FORECAST FOR FAR EASTERN KENTUCKY. WITH THIS TAKEN INTO ACCOUNT A NEW SET OF ZONES WILL BE ISSUED SHORTLY ALONG WITH AN UPDATED HWO. THE FRESHENED GRIDS HAVE BEEN SENT TO THE NDFD AND WEB SERVERS. UPDATE ISSUED AT 840 PM EDT FRI AUG 29 2014 00Z SFC ANALYSIS SHOWS GENERAL HIGH PRESSURE OVER THE AREA WITH LOW PRESSURE TO THE NORTHWEST. HOWEVER...THERE IS A WARM FRONT LIFTING NORTHEAST THROUGH EASTERN KENTUCKY. THIS WAS THE GENESIS OF A FEW SHOWERS AND THUNDERSTORMS DURING THE MID AND LATE AFTERNOON HOURS THAT ARE JUST NOW DISSIPATING OVER THE NORTHERN PARTS OF THE CWA. MOST PLACES DID STAY DRY TODAY SO THE THREAT OF WIDESPREAD FOG FORMING LATER TONIGHT IS LOW...THOUGH FOR PLACES THAT DID SEE RAIN AND THE DEEPER VALLEYS WILL LIKELY SEE AREAS OF FOG TOWARDS DAWN. OTHERWISE...A QUIET NIGHT WILL BE HAD THROUGH EASTERN KENTUCKY WITH CHANCES OF ADDITIONAL CONVECTION MINIMAL DESPITE THE NEARBY BOUNDARY. HAVE UPDATED THE GRIDS TO REFLECT THIS WHILE ALSO ADJUSTING THE LOW TEMPERATURES FOR A DECENT RIDGE TO VALLEY SPLIT ACROSS THE AREA. FINALLY...TWEAKED THE NEAR TERM GRIDS PER THE LATEST OBS...TRENDS... AND CONSSHORT GUIDANCE. THESE GRIDS HAVE BEEN SENT TO THE NDFD AND WEB SERVERS WITH A ZFP AND HWO UPDATE TO FOLLOW ONCE THE LAST OF THE CONVECTION FADES OVER THE NEXT HOUR OR SO. && .SHORT TERM...(THIS EVENING THROUGH SATURDAY NIGHT) ISSUED AT 357 PM EDT FRI AUG 29 2014 SURFACE HIGH PRESSURE IS CURRENTLY PARKED ACROSS NEW ENGLAND...WITH ELONGATED SURFACE LOW PRESSURE ALIGNED ALONG THE PLAINS STATES. A COLD FRONT EXTENDS SOUTHWEST FROM THE LOW DOWN NEAR THE OKLAHOMA PANHANDLE...WITH A WARM FRONT DANGLING EAST SOUTHEAST DOWN INTO EASTERN KENTUCKY. ALOFT...AN UPPER LEVEL LOW/TROUGH IS SPIRALING THROUGH THE CENTRAL PLAINS...WITH A RETREATING UPPER LEVEL RIDGE MOVING TOWARDS THE EASTERN SEABOARD. WARM AND HUMID CONDITIONS PREVAIL ACROSS MOST OF EASTERN KENTUCKY...WITH SOME LOCATIONS REPORTING IN THE LOWER 90S...WITH DEW POINTS RANGING FROM THE MID 60S TO THE LOWER 70S. DRIER AIR CAN BE FOUND DEEPER INTO SOUTH CENTRAL KENTUCKY AND TENNESSEE...WHERE SOME DEW POINTS HAVE MIXED OUT INTO THE 50S. ISOLATED SHOWERS AND THUNDERSTORMS HAVE POPPED UP NEAR AND AROUND THE WARM FRONT CURRENTLY EASING ITS WAY TO THE NORTH. THE MODELS REMAIN IN GOOD AGREEMENT THROUGH THE SHORT TERM...WITH THE UPPER LEVEL LOW/TROUGH GRADUALLY SWINGING TOWARDS THE GREAT LAKES REGION THROUGH SATURDAY NIGHT. AS DEEPER SOUTHWEST FLOW INCREASES ACROSS THE MISSISSIPPI VALLEY IN RESPONSE TO THIS...A SHORT WAVE TROUGH WILL MOVE OUT OF THE GULF REGION AND TRACK NORTHEAST INTO THE OHIO VALLEY BY SATURDAY NIGHT...BRINGING A ROUND OF SHOWERS AND SOME THUNDERSTORMS TO THE AREA. FOR TONIGHT...EXPECT AN OVERALL DECREASE IN THE ISOLATED CONVECTION ONCE AGAIN WITH THE LOSS OF HEATING...ALTHOUGH WITH THE SURFACE BOUNDARY LINGERING IN THE AREA THROUGH ABOUT 02 TO 03Z...WILL HANG ONTO A CORRIDOR OF ISOLATED POPS UNTIL THAT TIME. LIGHT SOUTHERLY WINDS SHOULD KEEP THE FOG RESTRICTED TO THE DEEPER RIVER VALLEYS TONIGHT...WITH SOME INCREASE IN HIGH CLOUDS TOWARDS DAWN. FOR SATURDAY...THE FIRST HALF OF THE DAY LOOKS TO REMAIN DRY...WITH TEMPERATURES LIKELY TOUCHING THE 90 DEGREE MARK IN SOME LOCATIONS...ESPECIALLY EAST...WHERE THERE WILL BE LESS CLOUD COVER. LATER IN THE DAY...DEEPER MOISTURE WILL BE ON THE INCREASE AS A DECENT LOW LEVEL JET ENSUES ACROSS THE TENNESSEE VALLEY. THE BLENDED 12 HOUR POPS CAME IN A BIT LEANER OVERALL...HOWEVER WAS A BIT LEARY TO BACK OFF TOO MUCH WITH SUCH DEEP MOISTURE ADVECTING IN LATE. FOR NOW...MAINTAINED A GOOD GRADIENT...WITH HIGHER CHANCES IN THE WEST...AND MUCH LESS IN THE EAST. BY SATURDAY NIGHT...THE SHORT WAVE TROUGH WILL MOVE IN...BRINGING A GOOD CHANCE OF MEASURABLE RAINS TO MOST LOCATIONS BY DAWN SUNDAY MORNING. HAVE FOLLOWED SUIT WITH THE GUIDANCE AND INCREASED POPS TO LIKELY FOR ALL BUT THE FAR EAST. INSTABILITY LOOKS TO BE ON THE WEAKER SIDE AND OVERALL FORCING IS MODEST...SO HAVE MENTIONED JUST A CHANCE OF THUNDER. PWATS INCREASE TO AROUND 2 INCHES DURING THIS TIME FRAME...SO HEAVY RAINS STILL LOOK POSSIBLE...AND WILL CONTINUE TO MENTION IN THE HWO. .LONG TERM...(SUNDAY THROUGH FRIDAY) ISSUED AT 357 PM EDT FRI AUG 29 2014 THE MODELS ARE STILL IN GOOD AGREEMENT WITH THE LARGE SCALE WEATHER PATTERN AND SENSIBLE WEATHER ACROSS THE EASTERN CONUS TO BEGIN THE PERIOD. THE DATA STILL STRONGLY SUGGESTS THAT A LARGE WELL DEFINED UPPER LEVEL TROUGH WILL PUSH EASTWARD ACROSS THE GREAT LAKES AND OHIO VALLEY REGIONS SUNDAY THROUGH MONDAY. AS THIS OCCURS...A LESS WELL DEFINED SURFACE FRONT IS PROGGED TO ALSO MOVE ACROSS CENTRAL AND EASTERN KENTUCKY...BRINGING WITH IT WIDESPREAD SHOWERS AND THUNDERSTORMS. THIS BOUNDARY WILL BE ABLE TO TAP INTO A SIGNIFICANT FEED OF GULF OF MEXICO MOISTURE...AND DUE TO THE SLOW MOVEMENT OF THE FRONT...AS WELL AS TALL AND SKINNY CAPE PROFILES STILL APPEARING IN THE FORECAST SOUNDINGS...ANY SHOWERS AND STORMS WILL BE EFFICIENT RAINFALL PRODUCERS. THIS WILL ONCE AGAIN LEAD TO THE POTENTIAL FOR LOCALLY HEAVY RAINFALL DURING THE DAY ON SUNDAY DURING PEAK HEATING. ONCE THE INITIAL TROUGH EXITS TO OUR EAST MONDAY NIGHT...A SECOND MUCH WEAKER ONE IS EXPECTED TO MOVE IN BEHIND IT. THIS IS WHERE THE MODELS BECOME A BIT DISJOINTED WITH ONE ANOTHER. THE OVERALL VIEW IS FOR PRECIPITATION CHANCES TO CONTINUE THROUGH THE REMAINDER OF THE WORK WEEK FROM TUESDAY ONWARD. THE MAIN QUESTIONS WILL BE THE TIMING AND THE EVOLUTION OF PRECIPITATION ASSOCIATED WITH THIS NEXT SYSTEM. BASED ON ALL THIS...BY FAR THE BEST CHANCE FOR RAIN WILL BE SUNDAY THROUGH MONDAY...WHICH IS THE TIME FRAME WITH THE HIGHEST PRECIP CHANCES...WITH A MUCH LOWER CONFIDENCE PRECIP FORECAST AFTER MONDAY NIGHT. WENT WITH GENERAL THUNDER CHANCES ACROSS THE BOARD DUE TO THE AMOUNT OF INSTABILITY AND MOISTURE FEED SHOWING UP IN ALL THE MODEL DATA. PRECIPITATION CHANCES MIGHT INCREASE SOME TOWARD THE END OF THE WEEK PER THE LATEST RUN OF THE ECMWF. WITH THAT MODEL TYPICALLY BEING THE MOST RELIABLE...THE SUPERBLEND MODEL DATA INGEST WAS ADJUSTED TOWARD THE NEW ECMWF FOR THE THURSDAY/FRIDAY TIME FRAME. TEMPERATURES DURING THE PERIOD LOOK TO BE AT OR EVEN SLIGHTLY ABOVE NORMAL BOTH DURING THE DAY AND NIGHT TIME PERIODS AS PERSISTENT SOUTHERLY TO SOUTHWESTERLY FLOW SETS UP ACROSS THE REGION. HIGHS EACH DAY SHOULD TOP OUT IN THE MID TO UPPER 80S...WITH NIGHTLY LOWS COMING IN AROUND 70. THE ONE EXCEPTION TO THIS RULE WILL BE SUNDAY...WHEN THE MERCURY IS EXPECTED TO ONLY MAKE IT TO AROUND 80 DEGREES...DUE TO THE INFLUENCE OF WIDESPREAD CLOUD COVER AND PRECIPITATION. && .AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT) ISSUED AT 135 AM EDT SAT AUG 30 2014 BEHIND THE FRI EVENING CONVECTION...SOME IFR OR WORSE FOG DEVELOPMENT SHOULD STILL OCCUR WITHIN THE DEEPER RIVER VALLEYS...AND NEAR WHERE THE HEAVIER RAIN FELL. HOWEVER...RAINFALL WAS VERY LIGHT OR MISSED THE TAF SITES...SO IFR OR LOWER VIS IS CURRENTLY NOT EXPECTED TO AFFECT ANY OF THE TAF SITES. JKL AND SJS WILL HAVE LINGERING MID LEVEL CLOUDS AND THIS SHOULD ALSO LIMIT THE FOG POTENTIAL. LOZ HAD THE MOST MEASURABLE RAINFALL. WE HAVE OPTED TO CONTINUE TO INCLUDE THE POTENTIAL FOR MVFR FOG AT SJS AND LOZ THROUGH 13Z AS BOT HAD AT LEAST A TRACE OF RAIN. CLOUDS WILL ALSO BE ON THE INCREASE DURING THE DAY ON SAT OUT AHEAD OF AN APPROACHING UPPER LEVEL SYSTEM. THE CONVECTIVE THREAT ASSOCIATED WITH THIS SYSTEM LOOKS TO HOLD OFF UNTIL 18Z OR LATER...WHEN VCTS WAS INCLUDED IN THE TAFS. WINDS WILL AVERAGE OUT OF THE SOUTH TO SOUTHWEST AT 5 TO 10 KTS OR LESS DURING THE PERIOD. && .JKL WATCHES/WARNINGS/ADVISORIES... NONE. && $$ UPDATE...JP SHORT TERM...GEOGERIAN LONG TERM...AR AVIATION...JP

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