Area Forecast Discussion
Issued by NWS Jackson, KY

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000 FXUS63 KJKL 251120 AAA AFDJKL AREA FORECAST DISCUSSION...UPDATED NATIONAL WEATHER SERVICE JACKSON KY 720 AM EDT FRI JUL 25 2014 .UPDATE...
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ISSUED AT 710 AM EDT FRI JUL 25 2014 THE FOG IS HOLDING ON STRONG THROUGH THE HEART OF THE CWA WHILE THE FRINGES ARE CLEARING. OVER THE FAR EAST...ALONG THE VIRGINIA BORDER THE VISIBILITIES NEVER GOT TOO DENSE AND THE WEB CAMS ARE SHOWING RELATIVELY CLEAR CONDITIONS. HAVE UPDATED THE GRIDS TO FINE TUNE THE DENSE FOG AND SKY COVER FOR THE NEXT HOUR OR SO BEFORE IT ALL STARTS TO CLEAR UP. ALSO...TWEAKED THE T AND TD GRIDS PER THE LATEST OBS AND TRENDS. THE UPDATED FORECAST HAS BEEN SENT TO THE NDFD AND WEB SERVERS.
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&& .SHORT TERM...(TODAY THROUGH SATURDAY) ISSUED AT 330 AM EDT FRI JUL 25 2014 07Z SFC ANALYSIS SHOWS COOL AND DRIER HIGH PRESSURE IN CONTROL OVER THE OHIO VALLEY AND EAST KENTUCKY. THIS HAS CLEARED THE SKY OF THE MID AND LOW LEVEL CLOUDS FROM EARLIER IN THE EVENING. AS A RESULT... WHEN COMBINED WITH THE MOIST BOUNDARY LAYER...FOG FORMED EARLY IN THE NIGHT AND HAS BECOME DENSE OVER MUCH OF THE AREA. AN SPS HAS BEEN ISSUED TO ADDRESS THIS...THOUGH A DENSE FOG ADVISORY APPEARS IN ORDER JUDGING FROM THE LATEST OBS AND WEB CAMS. THIS WILL BE ISSUED WITH THE ZONES AND GRID PACKAGE. OTHERWISE...WINDS ARE LIGHT THROUGH THE AREA WITH TEMPERATURES AND DEWPOINTS ALL WITHIN A COUPLE OF DEGREES OF 60. THE EXCEPTION IS FAR NORTHWEST PARTS OF THE AREA WHERE THERE REMAINS A DEWPOINT SPREAD OWING TO LOWER LEVELS OF MOISTURE. WILL LEAVE THESE PLACES OUT OF THE DENSE FOG ADVISORY...BUT MENTION PATCHY FOG IN THEIR GRIDS AND ZONES. THE MODELS ARE IN GOOD AGREEMENT ALOFT THROUGH THE SHORT TERM WITH A BRIEF RETREAT OF THE EASTERN TROUGH IN THE FACE OF THE STRONG WESTERN RIDGE FLATTENING OUT AND PUSHING HIGHER HEIGHTS EAST INTO KENTUCKY THROUGH MIDDAY SATURDAY. THIS WILL KEEP THE BULK OF ANY SHORTWAVE ACTIVITY NORTHEAST OF THE CWA THROUGH SATURDAY MORNING. HOWEVER...THE RIDGE PULLS BACK LATER SATURDAY UNDER THE INFLUENCE OF A MORE SIGNIFICANT MID LEVEL WAVE THAT WILL CROSS INTO THE WESTERN OHIO VALLEY THAT EVENING. THIS WAVE HAS BEEN A KEY ONE FOR THE PAST SEVERAL RUNS THAT THE MODELS BLOW UP WITH INDICATIONS OF A HEALTHY MCS. SPC HAS PLACED THE NORTHERN PART OF OUR CWA IN A SLIGHT RISK FOR THIS POTENTIAL LATER SATURDAY NIGHT...WITH DAMAGING WINDS THE GREATEST THREAT. GIVEN THE MODEL SIMILARITIES HAVE GONE WITH THE HIGHER RESOLUTION NAM12 MOST CLOSELY. SENSIBLE WEATHER WILL FEATURE A PLEASANT DAY WITH LOW AFTERNOON HUMIDITIES AND MOSTLY SUNNY SKIES...ONCE THE DENSE FOG BURNS OFF THIS MORNING. ALTHOUGH THE STORM TRACK WILL STAY NORTH OF THE AREA THROUGH MIDDAY SATURDAY...THE CLOUDS ASSOCIATED WITH ANY CONVECTIVE DEVELOPMENT WILL LIKELY DRIFT INTO OUR AREA AND KEEP TEMPS FROM BOTTOMING OUT TONIGHT AND LIKELY KEEP FOG CONFINED TO JUST THE VALLEYS. FOR SATURDAY...THE HEAT AND HUMIDITY RETURN TO THE AREA WITH A POTENTIAL FOR STORMS BY EVENING...MAINLY IN THE NORTH... DEPENDING ON THE MCS ACTIVITY TO THE NORTHWEST OUT AHEAD OF THE MAIN DEVELOPMENT ANTICIPATED LATER IN THE NIGHT. AGAIN USED THE CONSSHORT AS A STARTING POINT FOR TEMPERATURES... DEWPOINTS...AND WINDS THROUGH THE FIRST 24 HOURS AND THE CONSALL THEREAFTER. DID FINE TUNE LOWS TONIGHT FOR SOME SMALL RIDGE AND VALLEY DIFFERENCES. AS FOR POPS...WENT A TAD HIGHER THAN THE MOS NUMBERS FOR SATURDAY AFTERNOON...AND JUST SINGLE DIGITS...IN LINE WITH MOS...UNTIL THEN. .LONG TERM...(SATURDAY NIGHT THROUGH THURSDAY) ISSUED AT 357 AM EDT FRI JUL 25 2014 AN AMPLIFIED LONG WAVE TROUGH WILL BE THE MAIN WEATHER PLAYER DURING THE EXTENDED FORECAST. A CLOSED UPPER LEVEL LOW OVER NE CANADA WILL SLOWLY PUSH SOUTHWARD DURING THE COURSE OF THE EXTENDED PERIOD...WITH SEVERAL SHORTWAVES FOLLOWING THE LONG WAVE PATTERN...DRIVING OUR TEMPS AND PRECIP. THE FIRST OF THESE SHORTWAVES WILL MOVE INTO THE GREAT LAKES BY SUNDAY AFTERNOON. AT THE SURFACE...A LOW PRESSURE SYSTEM AND ASSOCIATED COLD FRONT WILL BE JUST AHEAD OF THE SHORTWAVE...PUSHING SE AS THE SHORTWAVE PROGRESSES. WARM HUMID AND UNSTABLE AIR WILL FILTER INTO THE REGION WELL AHEAD OF THE COLD FRONT...ALLOWING CONVECTION TO BEGIN AS EARLY AS 6 TO 12Z SUNDAY. IT SEEMS AS THOUGH THE LATEST MODELS ARE BACKING OFF ON THE START TIME OF THE PRECIP...SO THE ABOVE MENTIONED TIME HAS BEEN PUSHED BACK SLIGHTLY FROM THE PREVIOUS FORECAST. IN GOOD NEWS...ALL THE MID RANGE MODELS SEEM TO BE IN DECENT AGREEMENT WITH THIS SYSTEM...BOOSTING CONFIDENCE IN THIS LATER ONSET TIME. LOOKING AT THE LATEST FORECAST SOUNDINGS...STILL SUPPORTIVE OF A POSSIBLE SEVERE THREAT BY AFTERNOON/EVENING SUNDAY...WITH STEEP LAPSE RATES...CAPE VALUES 3-4.5 J/KG...STRONG WINDS IN BOTH THE MID AND UPPER LEVELS...AND DRYING IN THE MID LEVELS. NOT TO MENTION PWAT AMOUNTS WILL BE CLOSE TO 2 INCHES /1.93 FOR PIKEVILLE ACCORDING TO THE LATEST NAM/ FOR A 6 HOUR PERIOD BY SUNDAY AFTERNOON. NAM IS TRENDING SLIGHTLY HIGHER ON THE WATER CONTENT COMPARED TO THE GFS...BUT BOTH ARE STILL CONCERNEDLY HIGH FOR POSSIBLE FLASH FLOODING THREATS AS WELL. SPC HAS ALSO PUT MUCH OF KY AND POINTS TO THE E/NE IN A DAY 3 SLIGHT RISK FOR SEVERE THUNDERSTORMS AS WELL. THE UPPER LEVEL SHORTWAVE WILL MOVE TO OHIO BY 12Z MONDAY...WHILE THE SURFACE FRONT WILL HAVE PUSHED SE OF THE REGION. BOTH DRIER AND COOLER AIR WILL BEGIN FILTERING IN TO KY AS HIGH PRESSURE MOVES IN OVERHEAD. HOWEVER...WITH THE LINGERING INFLUENCE OF THE SHORTWAVE...AS WELL AS SOME LINGERING LOW LEVEL MOISTURE...THERE IS CONTINUED SUPPORT FOR SOME ISL/SCT SHOWERS AND TSTORMS REOCCURRING DURING THE AFTERNOON HOURS MONDAY. ONCE THE SHORTWAVE FINALLY MOVES WELL EAST OF THE REGION AND DRIER AIR CONTINUES TO TAKE HOLD...AND WE LOSE DIURNAL HEATING INFLUENCE...EXPECT ANY PRECIP CHANCES TO BE CUT OFF BY MONDAY NIGHT. THE WEATHER FOR BOTH TUESDAY AND WEDNESDAY LOOK GREAT...AND VERY UNSEASONABLE. THE LONGWAVE TROUGH...HAVING DROPPED SOUTHWARD...WILL ALLOW UNSEASONABLY COOL TEMPERATURES TO ADVECT INTO THE REGION. WHILE HIGHS MONDAY WILL BE IN THE MID AND UPPER 70S...BY TUESDAY THEY WILL HAVE DROPPED FURTHER...INTO THE LOW 70S FOR MUCH OF EASTERN KY. AIRMASS MODIFICATION AND ABUNDANT SUNSHINE WILL ALLOW TEMPERATURES TO MODERATE SOME BY WEDNESDAY...BUT STILL EXPECT A COOL UPPER 70S TO AROUND 80. AND WITH SURFACE HIGH PRESSURE STILL IN PLACE...AND DRY NRLY WINDS...PRECIP CHANCES WILL BE VIRTUALLY NIL. SADLY ALL GOOD THINGS MUST COME TO AN END. MODELS START TO LOSE AGREEMENT THIS FAR OUT IN THE FORECAST...BUT GENERAL CONSENSUS IS THAT SOME DIURNAL CONVECTION WILL START TO KICK BACK IN BY AFTERNOON THURSDAY ALONG THE HIGHEST TERRAIN...AS DEEPER MOISTURE SITS TO OUR SE. THEN THERE IS THE POTENTIAL FOR ANOTHER SHORTWAVE TO IMPACT THE REGION BY FRIDAY...BRINGING MORE WIDESPREAD CHANCES FOR CONVECTION. CONFIDENCE IN BOTH OF THESE IS STILL QUITE LOW AT THIS POINT GIVEN THE MODEL CONSENSUS...SO ACTUALLY TRENDED THE GIVEN ALLBLEND SOLUTION LOWER TO ONLY INCLUDE SLIGHT CHANCES AT THIS POINT ACROSS MUCH OF THE REGION. && .AVIATION...
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(FOR THE 12Z TAFS THROUGH 12Z SATURDAY MORNING) ISSUED AT 720 AM EDT FRI JUL 25 2014 DENSE FOG AND VLIFR CONDITIONS ARE BEING REPORTED AT ALL THE TAF SITES. EXPECT THE FOG TO START BREAKING UP JUST AFTER 12Z BEFORE QUICKLY GOING TO VFR WITH JUST SOME FAIR WEATHER CU AROUND 4K FEET. TONIGHT SOME HIGH CLOUDS WILL ARRIVE AND THIS SHOULD LIMIT THE RADIATIVE COOLING AND CONDITIONS CONDUCIVE TO SUCH WIDESPREAD FOG. AS A RESULT HAVE LIMITED THE FOG T OUR VALLEY LOCATIONS TOWARD THE END OF THE TAF CYCLE. WINDS WILL REMAIN LIGHT AND VARIABLE THROUGH THE FORECAST PERIOD.
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&& .JKL WATCHES/WARNINGS/ADVISORIES...
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DENSE FOG ADVISORY UNTIL 9 AM EDT THIS MORNING FOR KYZ052- 058>060-068-069-079-080-083>088-104-106>120.
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&& $$ UPDATE...GREIF SHORT TERM...GREIF LONG TERM...JMW AVIATION...GREIF

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