Area Forecast Discussion
Issued by NWS Jackson, KY

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FXUS63 KJKL 311405 AAA
AFDJKL

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE JACKSON KY
1005 AM EDT THU JUL 31 2014

.UPDATE...
ISSUED AT 1005 AM EDT THU JUL 31 2014

13Z SFC ANALYSIS SHOWS WEAK HIGH PRESSURE OVER EAST KENTUCKY. THE
EARLY MORNING FOG HAS JUST ABOUT BURNED OFF AND SKIES ARE CLEAR
OUTSIDE OF SOME LINGERING STRATUS IN THE FAR SOUTH BENEATH SOME
MID LEVEL ONES. WITH THE SUNSHINE THIS MORNING TEMPERATURES WILL
PROMPTLY REBOUND FROM THE LOWS...MAINLY IN THE MID AND UPPER 50S...
INTO THE LOW AND MID 80S BY LATE AFTERNOON. DEWPOINTS HAVE COME UP A
BIT...TOO...COMPARED TO YESTERDAY WITH VALUES IN THE UPPER 50S AND
LOWER 60S. WINDS ARE LIGHT OUT THERE...GENERALLY FROM THE SOUTH TO
SOUTHWEST. EXPECT A PLEASANT ENOUGH SUMMER DAY...WARMER THAN IT HAS
BEEN...THAT WILL BE DRY FOR MOST. THE EXCEPTION COULD BE DOWN ALONG
THE TENNESSEE AND VIRGINIA BORDERS WHERE SOME SHOWERS MAY SNEAK IN BY
EARLY EVENING FROM A SFC WAVE TO THE SOUTHEAST OF THE AREA. HAVE
UPDATED THE GRIDS TO FINE TUNE THE SKY AND WX GRIDS THIS MORNING AND
ALSO TO TAKE INTO ACCOUNT THE LATEST OBS...TRENDS...AND CONSSHORT
GUIDANCE. THESE GRIDS HAVE BEEN SENT TO THE NDFD AND WEB SERVERS
ALONG WITH THE ISSUANCE OF FRESHENED ZONES AND A FOG LESS HWO.

&&

.SHORT TERM...(TODAY THROUGH FRIDAY)
ISSUED AT 434 AM EDT THU JUL 31 2014

CENTER OF THE STRONG UPPER LEVEL LOW WILL ROTATE AROUND SOUTHERN
JAMES BAY DURING THE DAY TODAY AS IT REMAINS BLOCKED BETWEEN TWO
STRONG RIDGES...ONE ACROSS THE SW CONUS...AND ONE OFF THE NORTHERN
ATLANTIC COAST. UNLIKE PREVIOUS DAYS WHERE THE STRONG PULL OF
NORTHERLY AIR BROUGHT WITH IT UNSEASONABLE TEMPERATURES IN THE
70S...BY TODAY MID AND UPPER LEVEL FLOW WILL BECOME MORE WRLY...AND
THEN EVENTUALLY MORE SWRLY. THIS WILL BEGIN PULLING IN WARMER TEMPS
FROM THE WEST AND SOUTH.

IN ADDITION...THE NORTHERN CWA SHOULD EXPECT TO FIND ITSELF UNDER
THE INFLUENCE OF SURFACE HIGH PRESSURE AND NO MID LEVEL WAVES MOVING
ACROSS THE REGION TODAY. THE RESULT WILL BE PARTLY TO MOSTLY SUNNY
SKIES AND GOOD RADIATIONAL HEATING...WITH HIGH TEMPERATURES PULLING
BACK UP INTO THE LOW TO MID 80S...JUST SLIGHTLY BELOW NORMAL. THEN
FOR THE SOUTHERN CWA...A SLIGHTLY DIFFERENT STORY IS EXPECTED. A
SMALL WAVE OF MID LEVEL ENERGY WILL PASS NEAR THE STALLED SURFACE
BOUNDARY ALONG THE ATLANTIC SEABOARD TODAY...BRINGING A FOCUSED
CENTER OF PRECIP TO GA AND SC BY EARLY AFTERNOON. THIS PRECIP MAY
SPREAD FAR ENOUGH INTO OUR REGION UNDER THE SW FLOW LATE IN THE DAY
THAT A FEW ISOLATED POPS ALONG THE TN/VA BORDER WERE WARRANTED. IT
WILL ALSO CREATE AN INCREASE IN CIGS ALONG THE SOUTHERN BORDER
DURING THE AFTERNOON/EVENING...PREVENTING TEMPS FROM RISING QUITE AS
HIGH AS THOSE TO THE NORTH. UPPER 70S AND LOW 80S WILL BE EXPECTED
ACROSS THE SOUTHERN CWA. GIVEN THE LACK OF INSTABILITY ACROSS THE
OHIO RIVER VALLEY REGION...STUCK WITH THE MENTION OF RAIN SHOWERS
ONLY.

THE MID-LEVEL WAVE WILL MOVE NORTHWARD THROUGH THE LEE SIDE OF THE
TROUGH LATE TONIGHT AND THROUGH THE DAY TOMORROW. SHORT RANGE MODELS
ARE ALL STILL IN VERY GOOD AGREEMENT THAT THE EXTENT OF MOISTURE
FROM THIS WAVE WILL INCREASE DURING THE DAYTIME HOURS...EXPANDING
ACROSS ALL OF EASTERN KY BY AFTERNOON TOMORROW. GIVEN THE DAYTIME
INSTABILITY...AND CLOSER PROXIMITY TO THE WAVE ENERGY...INCLUDED
MENTION OF THUNDER DURING THE AFTERNOON HOURS. CLOUD COVER WILL
ACCOMPANY THIS WAVE...SPREADING FROM THE SOUTHERN CWA NW/WARD
OVERNIGHT TONIGHT...AND ENGULFING MUCH OF THE STATE BY TOMORROW. THE
CLOUD COVER IN ADDITION TO RAIN CHANCES WILL ACTUALLY WORK TO
REGULATE THE HIGH TEMPS TOMORROW. THE NORTHERN CWA WILL BE THE
WARMEST...AS THEY ARE EXPECTED TO SUCCUMB TO THE INFLUENCE OF THE
CLOUDS AND RAIN LAST. HOWEVER...THE HIGHER TERRAIN COULD SEE WELL
BELOW NORMAL TEMPS ONCE MORE...IN THE UPPER 70S TO AROUND 80. FOR THE
OVERNIGHT HOURS TONIGHT...CONTINUED WITH THE IDEA FOR A GOOD RIDGE
VALLEY SPLIT UNDER VERY LIGHT SERLY WINDS. THESE LIGHT WINDS AND AN
EXPECTED SUBSIDENCE INVERSION WITH THE SURFACE HIGH IN PLACE...COULD
BRING THE RETURN OF FOG TO THE VALLEY LOCATIONS ONCE MORE...THOUGH
INCOMING CLOUDS WILL PREVENT IT FROM BECOMING DENSE AND WIDESPREAD.
CONTINUED WITH PATCHY WORDING FROM PREVIOUS FORECAST.

.LONG TERM...(FRIDAY NIGHT THROUGH WEDNESDAY)
ISSUED AT 307 AM EDT THU JUL 31 2014

THE MODELS ARE IN GOOD AGREEMENT WITH THE AMPLIFIED RIDGE AND TROUGH
STAYING IN PLACE THROUGH THE END OF THE PERIOD. THE MODELS START OUT
ON FRIDAY NIGHT WITH THE UPPER TROUGH AXIS TO THE WEST OF THE AREA
AS SOME SHORT WAVE ENERGY DROPS OUT OF CANADA AND STARTS DIGGING AN
SHORT WAVE TROUGH OVER THE CENTRAL US. AS THIS TROUGH MOVES TOWARD
THE AREA IT WILL ERODE THE MID LEVEL CAPPING THAT HAS BEEN PRESENT.
WITH THE CAP GONE...THERE SHOULD BE ENOUGH INSTABILITY AND MOISTURE
TO BE ABLE TO GENERATE SOME SCATTERED SHOWERS AND THUNDERSTORMS
ACROSS THE AREA FROM FRIDAY NIGHT TROUGH SUNDAY MORNING. BY SUNDAY
EVENING THE UPPER TROUGH AXIS WILL HAVE MOVED TO EAST OF THE AREA
AND WILL THROTTLE THE CONVECTION. AS THIS SHORT WAVE MOVES TO THE
EAST ON MONDAY THE HEIGHTS OF THE REMAINING LONG WAVE TROUGH WILL BE
RISING AND A UPPER LOW WILL BE TRYING BREAK OFF AND DIG TO THE
SOUTH. BY TUESDAY...THERE WILL BE A WEAK UPPER LOW OVER THE DEEP
SOUTH AND THE BLOCKING RIDGE WILL START TO WEAKEN. THIS WILL ALLOW A
SHORT WAVE TO DROP INTO THE CENTRAL US AND START TO PUSH THE FRONTAL
BOUNDARY INTO CENTRAL OHIO...STILL WELL NORTH OF THE AREA. THIS WILL
KEEP THINGS FAIRLY DRY THROUGH THE END OF THE PERIOD. THE
TEMPERATURES WILL REMAIN BELOW SEASONABLE NORMS THROUGH MONDAY AND
THEN SUMMER TEMPERATURES RETURN ON TUESDAY AND WEDNESDAY. WENT WITH
THE MODEL BLEND WITH SOME BIAS CORRECTIONS APPLIED.

&&

.AVIATION...(FOR THE 12Z TAFS THROUGH 12Z FRIDAY MORNING)
ISSUED AT 708 AM EDT THU JUL 31 2014

ONCE FOG BURNS OFF AT KSME...EXPECT VFR CONDITIONS THROUGH THE BULK
OF THE FORECAST PERIOD FOR THE TAF SITES. EXCEPTION WILL BE LATE
TONIGHT WHEN THE VALLEY SITES ARE EXPECTED TO SEE ANOTHER BOUT OF
POTENTIAL MVFR CONDITIONS FROM FOG...WHILE THE RIDGES MAY DIP DOWN
FOR AN HOUR OR SO. CANNOT RULE OUT LOWER VSBY AND CIGS FOR A TIME
CLOSER TO DAWN AT KSME DUE TO LIGHT BUT PREDOMINATE SW FLOW...AS WAS
THE CASE THIS MORNING. WINDS THROUGH THE PERIOD WILL BE LIGHT AND
VARIABLE. VFR CLOUDS WILL BE ON THE INCREASE THROUGH THE DAY TODAY AT
KSME AND KLOZ AHEAD OF RAIN SHOWER POTENTIAL POISED TO IMPACT FAR SE
KENTUCKY THIS EVENING AND OVERNIGHT. THESE SHOWERS WILL REMAIN
ISOLATED AND WILL POTENTIALLY NEAR THE TAF SITES SO LATE IN THE
FORECAST PERIOD THAT UNCERTAINTY WARRANTED IT NOT BEING INCLUDED IN
THE TAF AT THIS TIME.

&&

.JKL WATCHES/WARNINGS/ADVISORIES...
NONE.
&&

$$

UPDATE...GREIF
SHORT TERM...JMW
LONG TERM...JJ
AVIATION...JMW




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