Area Forecast Discussion
Issued by NWS Jackson, KY

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000
FXUS63 KJKL 200555 AAC
AFDJKL

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE JACKSON KY
155 AM EDT SAT SEP 20 2014

.UPDATE...
ISSUED AT 140 AM EDT SAT SEP 20 2014

HOURLY GRIDS HAVE BEEN FRESHENED UP BASED ON RECENT OBSERVATIONS AND
TRENDS. THIS LED TO SLIGHTLY COLDER MIN T IN A COUPLE OF SPOTS ACROSS
THE NORTH...WITH THE MAIN CHANGE BEING MORE FOG IN THE GRIDS FOR
VALLEY LOCATIONS OUTSIDE OF THE HIGHEST TERRAIN WHERE THE PRESSURE
GRADIENT WAS WEAKER. WE HAVE RECEIVED A SPOTTER REPORT OF DENSE FOG
NEAR THE RED RIVER IN POWELL COUNTY AND 11-3.9 SAT IMAGERY SUPPORTS
VALLEY FOG AT PRESENT IN PARTS OF THE LIKING...BIG SANDY...KENTUCKY
AND RED RIVER VALLEYS. SOME OF THE FOG SHOULD AGAIN BE DENSE
GENERALLY ALONG THE LARGER CREEKS AND STREAMS AND ESPECIALLY RIVERS
AND LARGER LAKES. THE PRESSURE GRADIENT IS EXPECTED TO RELAX A BIT
OVERNIGHT ACROSS THE SOUTHEAST PART OF THE CWA SO OUTSIDE OF WHERE
SOME CLOUDS DEVELOP IN THE WARM SECTOR...VALLEY FOG SHOULD ALSO
DEVELOP THERE TOWARD DAWN.

SOME OF THE GUIDANCE INDICATES THE POTENTIAL FOR A FEW STRAY SHOWERS
AS A WEAK DISTURBANCE APPROACHES...MAINLY ACROSS THE WESTERN AND
NORTHWESTERN PARTS OF THE CWA LATER TONIGHT INTO EARLY ON SATURDAY.
CONFIDENCE IN THIS IS NOT ALL THAT HIGH...BUT IT DOES HAVE SUPPORT
FROM THE NAM...SOME OF THE RECENT HRRR RUNS AND SOME PRIOR BUT NOT
THE MOST RECENT RAP RUN. WE WILL CONTINUE TO EVALUATE THIS POTENTIAL
FOR THE SCHEDULED MORNING FORECAST RELEASE.

UPDATE ISSUED AT 1027 PM EDT FRI SEP 19 2014

USED OBSERVED TEMPERATURES AND DEW POINTS TO ADJUST HOURLY GRIDS FOR
TONIGHT...BLENDING TOWARD THE PREEXISTING FORECAST BY MORNING. NO
SUBSTANTIVE CHANGES TO THE OVERALL FORECAST WERE MADE.

UPDATE ISSUED AT 729 PM EDT FRI SEP 19 2014

HAVE UPDATED TO ALLOW FOR A FASTER DROP IN VALLEY TEMPS THIS
EVENING. ALSO...REDUCED SKY COVER FOR MOST AREAS THIS EVENING.
MESOSCALE MODELS ARE PERSISTENT IN SHOWING CLOUDS DEVELOPING NEAR OUR
WESTERN BORDER LATE TONIGHT INTO SATURDAY MORNING...A WELL AS SOME
SHOWERS. HAVE ACCOUNTED FOR A FEW CLOUDS...BUT KEPT THE FORECAST IN
THE JKL FORECAST AREA DRY AT THIS POINT.

&&

.SHORT TERM...(THIS EVENING THROUGH SATURDAY NIGHT)
ISSUED AT 307 PM EDT FRI SEP 19 2014

A LARGE DOME OF HIGH PRESSURE WILL REMAIN ANCHORED OVER THE EAST
COAST INTO THE WEEKEND...PROVIDING A DRY START TO THE WEEKEND. STILL
A REMOTE CHANCE OF AN ISOLATED SHOWER ACROSS PIKE COUNTY LATER THIS
EVENING...BUT CHANCES SEEM TO BE DIMINISHING WITH EVERY HOUR THAT
PASSES. THE CU JUST DOES NOT LOOK ALL THAT IMPRESSIVE.
REGARDLESS...UNTIL INSTABILITY WANES THIS EVENING CANNOT RULE OUT A
BRIEF POP UP SHOWER. SKIES WILL CLEAR OUT AGAIN TONIGHT. WITH
DEW POINTS CLIMBING HIGHER TODAY...AND CLEARING SKIES...ANOTHER NIGHT
OF FOG CAN BE EXPECTED ACROSS THE AREA. SHOULD BE A FAIRLY TYPICAL
FOG FOR THIS TIME OF YEAR. HIGHS WILL CLIMB TO THE HIGHEST READINGS
OF THE WEEK ON SATURDAY AS TEMPERATURES CLIMB INTO THE LOW 80S DURING
THE AFTERNOON. CLOUDS WILL BE ON THE INCREASE SATURDAY NIGHT AS A
COLD FRONT PUSHES SOUTH INTO THE OHIO RIVER VALLEY. PRECIPITATION
ASSOCIATED WITH THIS BOUNDARY COULD MAKE IT INTO AREAS NORTH OF 1-64
PRIOR TO 12Z SUNDAY...BUT IT APPEARS THE MAIN PRECIPITATION WITH THE
FRONT SHOULD COME COME LATER ON SUNDAY. WITH CLOUDS AND SURFACE
MOISTURE INCREASING SATURDAY NIGHT...A MILDER NIGHT IS ON TAP WITH
LOWS ONLY INTO THE 60S.

.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 322 PM EDT FRI SEP 19 2014

ALL OF THE WEATHER IS AT THE FRONT END OF THIS FORECAST PERIOD AS A
COLD FRONT IS SET TO SWEEP QUICKLY ACROSS THE AREA ON SUNDAY.
MOISTURE RETURN IN ADVANCE OF THE FRONT IS NOT GREAT WITH PWATS ONLY
CREEPING UP TO ABOUT 1.5 INCHES IN A THIN RIBBON. COUPLED WITH ONLY
WEAK INSTABILITY...ANTICIPATE A NARROW BAND OF SHOWERS AND A FEW
THUNDERSTORMS TO ACCOMPANY THE FRONT DURING THE DAY ON SUNDAY. THE
BULK OF THIS ACTIVITY SHOULD BE TO OUR SOUTHEAST BY SUNDAY EVENING.
FOLLOWING THIS FRONTAL PASSAGE...A LARGE DOME OF HIGH PRESSURE WILL
SLIDE ACROSS THE OHIO VALLEY. COUPLED WITH A BUILDING RIDGE ALOFT...
THIS SHOULD RESULT IN A PROLONGED PERIOD OF DRY WEATHER WITH
PLEASANT TEMPERATURES NEXT WEEK. THERE IS ONE POSSIBLE FLY IN THE
OINTMENT THOUGH AS FORECAST MODELS HINT THAT A WEAK UPPER LOW MAY
GET TRAPPED TO THE SOUTH OF THE UPPER RIDGE. ALL SIGNS CURRENTLY ARE
THAT ANY ASSOCIATED MOISTURE WITH THIS LOW WOULD STAY TO OUR SOUTH
AND EAST SO WILL NOT GIVE THIS ANY PLAY IN OUR LOCAL FORECAST AT
THIS TIME.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT)
ISSUED AT 150 AM EDT SAT SEP 20 2014

ASIDE FROM VALLEY FOG DEVELOPING...AND THEN LIFTING AND DISSIPATING
THROUGH 13Z TO 14Z...VFR CONDITIONS WITH LIGHT WINDS WILL PREVAIL
DURING THE PERIOD. A COLD FRONT AND ASSOCIATED INCREASE IN CLOUDS IS
EXPECTED LATE IN THE PERIOD. THE FOG IS AGAIN EXPECTED TO FOLLOW ITS
TYPICAL LATE SUMMER/EARLY AUTUMN PATTERN OF DEVELOPING FIRST IN DEEP
VALLEYS AND THEN GROWING IN BREADTH AND DEPTH...WITH THE POTENTIAL TO
BEGIN TO REACH SOME RIDGES AND OPEN TERRAIN BY DAWN...SUCH AS MVFR AT
SJS IF WINDS SLACKEN AND POSSIBLY MVFR AT SME WHERE THE CURRENT
DEWPOINT DEPRESSION IS LOW BUT THERE ARE SCT CLOUDS AS WELL. THE
LARGER RECENT OBSERVED DEWPOINT DEPRESSION OF 7 AT LOZ POINTS TOWARD
ANY FOG THAT DEVELOPS BEING IN THE VFR RANGE.

&&

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

$$

UPDATE...JP
SHORT TERM...KAS
LONG TERM...ABE
AVIATION...JP






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