Area Forecast Discussion
Issued by NWS Jackson, KY

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000
FXUS63 KJKL 230821
AFDJKL

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JACKSON KY
421 AM EDT SAT AUG 23 2014

.SHORT TERM...(TODAY THROUGH SUNDAY)
ISSUED AT 421 AM EDT SAT AUG 23 2014

WHILE 500MB HEIGHTS CONTINUE TO PUSH A STRONG RIDGING PATTERN INTO
THE LOWER MISSISSIPPI RIVER VALLEY AND DEEP SOUTH...TROUHGING
CONTINUES TO LINGER ALONG THE NEW ENGLAND SEABOARD. EASTERN KY/S
POSITION IN THE TRANSITION ZONE WILL CONTINUE TO MAKE US SUSCEPTIBLE
TO SHORTWAVE ACTIVITY THROUGH THE SHORT TERM. AT THE SURFACE...A
STATIONARY BOUNDARY PARKED JUST NORTH OF THE OHIO RIVER YESTERDAY
WAS THE FOCAL POINT FOR A STRONG PULL OF WAA AND UNSTABLE MOIST AIR
FROM THE GULF. AS TEMPS ROSE DURING THE AFTERNOON...THE ATMOSPHERE
BECAME MORE UNSTABLE...AND THE FRONT PROVIDED THE LIFT NEEDED TO
INITIATE STRONG SHOWERS AND THUNDERSTORMS CAPABLE OF PRODUCING
TORRENTIAL RAINS. THESE STORMS THEN MOVED S AND SE INTO EASTERN KY
THROUGHOUT THE EVENING AND OVERNIGHT...CAUSING FLASH FLOODING ACROSS
MANY LOCATIONS.

FOR TODAY...THIS FRONTAL BOUNDARY WILL SHIFT ONLY
SLIGHTLY...BECOMING MORE N/S ORIENTED ALONG THE ERN KY BORDER
ACCORDING TO THE LATEST GFS ANALYSIS. GIVEN THE SIMILAR SET UP TO
YESTERDAY...EXPECT A NEAR REPEAT OF EVENTS...WITH THE BEST
CONVECTION EXPECTED MORE OVER THE WRN AND SWRN PORTIONS OF THE CWA.
THIS WILL NOT LIMIT OTHER SCATTERED CONVECTION FROM DEVELOPING
ELSEWHERE ACROSS THE CWA AS WELL. PWAT VALUES ARE STILL AROUND/ABOVE
2 INCHES DURING THE AFTERNOON AND EVENING...WITH STORM MOTION AND
0-6KM WINDS GENERALLY 10-12 KNOTS OR LESS. SLOW MOVING HEAVY RAINERS
WILL BE THE STORY ONCE MORE. WHILE THUNDERSTORMS ARE DEFINITELY
POSSIBLE...GENERALLY NE FLOW AND SOME MID LEVEL CAPPING MAY BE
ENOUGH TO KEEP SEVERE POTENTIAL AT BAY FOR THE MOST PART. BIGGEST
CONCERN WILL OBVIOUSLY BE THE FLASH FLOODING POTENTIAL...ESPECIALLY
GIVEN THE ONGOING SATURATED/ABOVE SATURATED CONDITIONS ACROSS
EASTERN KY.

BY THIS EVENING/OVERNIGHT...THE FRONTAL BOUNDARY WILL MAKE A QUICK
PUSH SW ACROSS THE CWA. THIS...AND LOSS OF DIURNAL HEATING AND
INSTABILITY WILL QUICKLY REDUCE POPS ACROSS THE REGION...THOUGH
LATEST NAM12 SOUNDINGS ARE STILL SHOWING PWAT VALUES BETWEEN 1.75
AND 2.0 IN. OVERNIGHT SATURDAY NIGHT AS WELL. IN OTHER
WORDS...EXPECT COVERAGE AND THUNDER POTENTIAL TO LESSON
SUBSTANTIALLY...THOUGH ANY STORMS THAT DO PERSIST WILL CONTINUE TO
PUT DOWN HEAVY RAIN WHILE EXPERIENCING A SLOWING STORM MOTION. FLASH
FLOODING THREATS...THEREFORE...WILL CONTINUE INTO THE OVERNIGHT
HOURS.

THE FRONTAL BOUNDARY WILL SHIFT OFF TO OUR SW FOR THE FORECAST
SUNDAY...WITH THE UPPER LEVEL RIDGE ENCOMPASSING MUCH OF THE OHIO
RIVER VALLEY. DIURNAL DRIVEN INSTABILITY WILL CONTINUE...AS A WEAK
SURFACE DISTURBANCE SETS UP ACROSS THE SOUTH CENTRAL PORTION OF THE
STATE. THIS WILL BE THE PRIMARY EPICENTER FOR STORM
DEVELOPMENT...HOWEVER ANYTHING STRONG IS HIGHLY UNLIKELY GIVEN THE
UNSUPPORTED WEAK WIND PROFILE. PWAT VALUES WILL SHOW A LESSENING
TREND...BUT ARE STILL STICKING AROUND THE 1.75 IN. RANGE WITH LITTLE
TO NO STORM MOTION. WOULDN/T BE SURPRISED TO SEE SOME MORE GOOD
HEAVY SOAKERS THIS DAY AS WELL. CHANCES FOR SHOWERS WILL QUICKLY
DROP OFF WITH LOSS OF DAYTIME HEATING IN THE EVENING.

GIVEN THE CONTINUED BUILDING HEIGHTS ACROSS THE REGION...AND A MORE
TROPICAL AIRMASS MOVING INTO THE OHIO RIVER VALLEY...TEMPS WILL
CONTINUE TO CLIMB TO JUST BELOW THE 90 DEGREE MARK TODAY AND
TOMORROW...WITH HIGH HUMIDITY VALUES MAKING IT FEEL CLOSER TO 100
DEGREES. CLOUDS AND THE POTENTIAL FOR SHOWERS WILL KEEP TEMPS FROM
REACHING EVEN HIGHER. MIN TEMPS WILL REMAIN WELL ABOVE NORMAL UNDER
THIS WARM AIRMASS...ONLY DIPPING DOWN INTO A HUMID UPPER 60S AND LOW
70S.

.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 255 PM EDT FRI AUG 22 2014

STRONG RIDGING WILL CONTINUE TO DEVELOP OVER THE EASTERN CONUS LATE
IN THE WEEKEND THROUGH THE EARLY PART OF NEXT WEEK. AS THE CENTER OF
THE HIGH PUSHES OVERHEAD EARLY NEXT WEEK...IT WILL SEND SOME
SLIGHTLY DRIER AIR INTO EASTERN KENTUCKY...FINALLY BRINGING A
TEMPORARY END TO THE RAIN CHANCES. HAVE BEEN GOING WITH LOW POPS
EARLY NEXT WEEK...BUT GIVEN THE NATURE OF THE DRY AIR...HAVE OPTED
TO GO WITH DRY WEATHER EARLY TO MIDDLE PART OF NEXT WEEK. IN
FACT...DEWPOINTS MAY GET LOW ENOUGH TO WARRANT A FEW TEMPERATURES
INTO THE LOWER AND MIDDLE 60S TUESDAY AND WEDNESDAY MORNINGS. CANNOT
RULE OUT SOME SHOWERS ON SUNDAY OR SUNDAY EVENING PRIOR TO THE
DEPARTURE OF THE BETTER MID LEVEL MOISTURE. HOWEVER...EVEN THIS
ACTIVITY WILL LIKELY BE LESS THAN WHAT WE HAVE SEEN RECENTLY.
THUS...OVERALL...LOOK FOR A QUIETER STRETCH OF WEATHER INTO THE
MIDDLE OF NEXT WEEK. BY LATE IN THE PERIOD. THE RIDGE MAY BEGIN TO
BREAK DOWN AS A SHORTWAVE TROUGH MOVING ACROSS THE GREAT LAKES
PUSHES A BOUNDARY SOUTHWARD INTO THE OHIO RIVER VALLEY. TOO MUCH
UNCERTAINTY WITH THIS BOUNDARY TO GO WITH ANYTHING MORE THAN CHANCE
POPS FROM THURSDAY ONWARD. THE 00Z ECMWF HAD PUT THE BOUNDARY OVER
EASTERN KENTUCKY...BUT THE 12Z RUN HAS KEPT IT TO THE NORTH THROUGH
WEEKS END. IF THE BOUNDARY STAYS NORTH...PROBABLY GOING TO SEE
WARMER AND HUMID CONDITIONS PERSISTING THROUGH THE SECOND HALF OF
NEXT WEEK.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SATURDAY EVENING)
ISSUED AT 735 PM EDT FRI AUG 22 2014

CLUSTERS OF THUNDERSTORMS WILL HEAVY RAINFALL WILL BE AFFECTING JKL
AND SJS THROUGH 2 OR 3Z THIS EVENING. BASED ON CURRENT RADAR IMAGERY
IT APPEARS THAT JKL WILL EXPERIENCE THE LONGEST DURATION OF
THUNDERSTORM ACTIVITY THIS EVENING. THE PRIMARY HAZARDS TO FOCUS ON
FOR TAF PURPOSES WILL BE LOCALLY HEAVY RAINFALL THAT COULD LEAD TO
FLASH FLOODING AND FREQUENT IN CLOUD AND CLOUD TO GROUND LIGHTNING.
IN GENERAL VFR CONDITIONS WILL BE EXPECTED OVERNIGHT...BUT ANY
THUNDERSTORMS THAT AFFECT JKL OR SJS COULD LEAD TO MVFR TO PERHAPS
IFR CONDITIONS DEPENDING ON HOW INTENSE THE RAIN AND WINDS WITH THESE
STORMS ARE. THE STORMS SHOULD GRADUALLY DIE DOWN AS THE SUN CONTINUES
TO SET...GIVING WAY TO SCATTERED RAIN SHOWERS AND PERHAPS AN ISOLATED
RUMBLE OF THUNDER OVERNIGHT. THE NEXT ROUND OF MORE WIDESPREAD
SHOWERS AND STORMS ARE EXPECTED TO AFFECT ALL OF THE TAF SITES FROM
15Z ONWARD ON SATURDAY. AS FOR TONIGHT...LOZ AND SME MIGHT BE SPARED
THE BULK OF THUNDERSTORM ACTIVITY...BUT THIS WILL NEED TO BE
MONITORED CLOSELY OVER THE NEXT FEW HOURS.


&&

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

$$

SHORT TERM...JMW
LONG TERM...KAS
AVIATION...AR





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