Area Forecast Discussion
Issued by NWS Jackson, KY

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FXUS63 KJKL 250757
AFDJKL

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JACKSON KY
357 AM EDT FRI JUL 25 2014

.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...(FOR THE 06Z TAFS THROUGH 06Z FRIDAY NIGHT)
ISSUED AT 125 AM EDT FRI JUL 25 2014

ALTHOUGH IT WILL BE HALTING AND STAGGERED THROUGH THE NIGHT...THE
TREND IN THE CONDITIONS AT THE TAF SITES WILL BE DOWNWARD.
ACCORDINGLY...HAVE TAKEN THEM DOWN TO VLIFR FOR A TIME TOWARD DAWN
WITH SOME TEMPOS ON THE WAY DOWN. THE FOG WILL CLEAR BY MID MORNING
WITH JUST SOME VFR FAIR WEATHER CU LEFT BEHIND INTO THE AFTERNOON.
WINDS WILL REMAIN LIGHT AND VARIABLE THROUGH THE FORECAST PERIOD.


&&

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

$$

SHORT TERM...GREIF
LONG TERM...JMW
AVIATION...GREIF





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