Area Forecast Discussion
Issued by NWS Jackson, KY

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FXUS63 KJKL 300643
AFDJKL

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JACKSON KY
243 AM EDT THU JUL 30 2015

.UPDATE...
ISSUED AT 243 AM EDT THU JUL 30 2015

COLD FRONT WAS POSITIONED FROM NEAR KBNA TO NEAR KDAY. CONVECTION
HAS ALMOST DIED OUT OVER THE LOCAL AREA...BUT CAN NOT RULE OUT
SOMETHING POPPING UP YET AHEAD OF THE FRONT. HAVE LOWERED POPS TO
20 PERCENT...AND THEN DROPPING BELOW THE THRESHOLD FOR THE MENTION
OF PRECIP AFTER THE FRONT PASSES SOUTHEAST IN THE MORNING.

UPDATE ISSUED AT 1020 PM EDT WED JUL 29 2015

THE COLD POOL ASSOCIATED WITH THE LINE OF STORMS HAS CONTINUED TO
CONSOLIDATE TO THE WEST AND SOUTH OF OUR AREA. ONLY A FEW OF OUR
SOUTHWEST COUNTIES WILL SEE LIKELY RAINS OVER THE NEXT HOUR OR SO.
THE REMNANT STRATIFORM RAINFALL ACROSS CENTRAL KENTUCKY IS NOT
MOVING MUCH...AND WILL GRADUALLY WEAKEN...MAINLY IN PLACE. THE
LAST FEW RUNS OF THE HRRR HAS GENERALLY CAUGHT ON TO THE ONGOING
CONVECTIVE TRENDS. AS SUCH...IT APPEARS THAT THERE MAY NOT BE MUCH
IN THE WAY OF ACTIVITY UNTIL THE ACTUAL FRONTAL BOUNDARY MOVES
SOUTHEAST ACROSS THE AREA DEEPER INTO THE OVERNIGHT HOURS...WHEN A
SLIGHT UPTICK IN ACTIVITY MAY OCCUR. WILL THEREFORE HANG ONTO
SLIGHT TO CHANCE POPS. ALSO ADJUSTED THE LOWS UP A TOUCH...AS THE
PUSH BEHIND THE FRONT IS NOT VERY STRONG. THE BEST CHANCE OF
SEEING SOME UPPER 60 DEGREE READINGS LOOKS TO BE ALONG AND NORTH
OF I-64. UPDATES HAVE BEEN SENT.

UPDATE ISSUED AT 813 PM EDT WED JUL 29 2015

THE LATEST RADAR MOSAIC SHOWS A CONVECTIVE LINE ACROSS CENTRAL
AND WESTERN KENTUCKY. NEW CELLS HAD BEEN MORE LIVELY A BIT FURTHER
NORTHEAST EARLIER...BUT SOME PRECURSORY STORMS TAPPED INTO THE
BETTER AVAILABLE AIR MASS...AND NOW THERE IS GENERALLY A WEAKENING
TREND ON THE EASTERN FLANK OF THE LINE...WITH BETTER COLD POOL AND
ASSOCIATED NEW DEVELOPMENT ALIGNING MORE TOWARDS THE SOUTH...WHERE
BETTER INSTABILITY REMAINS. STILL...THINK THAT SOME DEBRIS CELLS
WILL MAKE IT INTO THE WEST IN THE NEXT 1 TO 2 HOURS...AND HAVE
UPPED THE POPS TO HIGH CHANCE TO LIKELY FOR THOSE LOCATIONS. AS WE
LOSE HEATING...EXPECT AN OVERALL GRADUAL DIMINISHMENT...HOWEVER
WILL STILL HAVE TO KEEP AN EYE ON HEAVY RAINERS...GIVEN THE HIGH
PWATS AND THE POTENTIAL FOR TRAINING.

&&

.SHORT TERM...(THIS EVENING THROUGH THURSDAY NIGHT)
ISSUED AT 343 PM EDT WED JUL 29 2015

AS OF MID AFTERNOON A MID LEVEL RIDGE WAS CENTERED OVER THE
SOUTHERN PLAINS REGION...WITH A CLOSED MID LEVEL LOW OVER
NORTHWESTERN ONTARIO AND THE ASSOCIATED TROUGH SOUTH INTO THE MS
VALLEY REGION. AT THE SFC...AN AREA OF LOW PRESSURE WAS CENTERED
OVER ONTARIO WITH A COLD FRONT SOUTH INTO THE CENTRAL GREAT LAKES
AND THEN SOUTHWEST INTO THE MID MS VALLEY AND CENTRAL PLAINS.
CONVECTION HAS DEVELOPED ALONG OR IN ADVANCE OF THIS FRONT OVER OH
AND IN SOUTHWEST INTO WESTERN KY. ADDITIONAL CONVECTION HAS
DEVELOPED NEAR A MOISTURE GRADIENT EVIDENT IN PW FROM NORTHERN KY
SOUTH INTO CENTRAL KY. THIS CONVECTION HAS BEEN GENERALLY SLOW
MOVING WITH HEAVY RAINFALL RATES. AREA WIDE...A WARM AND MOIST
AIR MASS IS IN PLACE WITH TEMPERATURES IN THE MID TO UPPER 80S TO
NEAR 90 AND DEW POINTS IN THE UPPER 60S TO MID 70S.

THE CLOSED MID LEVEL LOW WILL TRACK TO HUDSON BAY WITH THE
TRAILING SHORTWAVE TROUGH MOVING THROUGH THE GREAT LAKES AND MID
AND UPPER OH VALLEY REGION TONIGHT. THIS SHORTWAVE TROUGH WILL
MOVE INTO THE NORTHEASTERN CONUS THROUGH THURSDAY. AT THE SAME
TIME...THE MID LEVEL RIDGE WILL RETROGRADE AND AMPLIFY AND BECOME
CENTERED OVER THE SOUTHERN ROCKIES OR FOUR CORNERS REGION. THIS
WILL PUT THE REGION IN NW FLOW ALOFT LATE IN THE PERIOD. AT THE
SFC...THE COLD FRONT WILL CROSS THE REGION BY LATE TONIGHT OR
EARLY ON THURSDAY. THEN...HIGH PRESSURE WILL BUILD IN BEHIND THE
DEPARTING COLD FRONT AND USHER IN SLIGHTLY COLDER...BUT MORE
NOTICEABLY DRIER AIR INTO THE REGION.

RATHER MEAGER MID LEVEL FORCING AND NON OPTIMAL TIMING OF THE
FROPA DURING THE LATE EVENING INTO OVERNIGHT HOURS SHOULD LIMIT
CONVECTION THIS EVENING AND TONIGHT TO ISOLATED TO SCATTERED
COVERAGE. IT STILL APPEARS THAT THERE SHOULD BE A PEAK IN COVERAGE
OVER THE NEXT 3 HOURS OR SO...AND THEN MORE ORGANIZED CONVECTION
WITH A POSSIBLE BROKEN LINE OR LINE SEGMENTS OF SHOWERS AND
THUNDERSTORMS AS THE COLD FRONT MOVES THROUGH. WITH RELATIVELY
SLOW STORM MOTIONS EXPECTED DUE TO WEAK FLOW ALOFT AND A MOIST
AIR MASS IN PLACE...ANY STRONGER THUNDERSTORMS COULD PRODUCE VERY
HEAVY RAINFALL RATES AND OUTFLOW WIND GUSTS IN EXCESS OF 30 MPH
WILL BE POSSIBLE THIS EVENING SIMILAR TO A GUST OBSERVED OVER
CENTRAL KY EARLIER THIS AFTERNOON.

A SHOWER OR POSSIBLY A THUNDERSTORM COULD LINGER EARLY ON
THU...OVER THE SOUTHEASTERN CWA...PARTICULARLY NEAR THE VA BORDER.
OTHERWISE... AS DRIER AIR MOVES IN THROUGHOUT THE COLUMN SKIES
SHOULD BECOME MOSTLY SUNNY IN MOST LOCATIONS ON THU AFTERNOON.
WITH THE HIGH BUILDING IN...CLEAR SKIES AND LIGHT WINDS SHOULD SET
THE STAGE FOR VALLEY FOG FORMATION LATE IN THE PERIOD. ENOUGH
DRIER AIR SHOULD WORK IN FOR SOME OF THE NORMALLY COLDER LOCATIONS
ALONG...OR NORTH OF THE MTN PARKWAY COULD TOUCH THE UPPER 50S.

.LONG TERM...(FRIDAY THROUGH WEDNESDAY)
ISSUED AT 256 PM EDT WED JUL 29 2015

THE EXTENDED PERIOD LOOKS FAIRLY BENIGN AS SURFACE HIGH PRESSURE
TAKES CONTROL OF THE REGION THROUGH EARLY NEXT WEEK. THIS WILL
ALLOW FOR SLIGHTLY COOLER AND DRIER AIR TO FILTER INTO THE REGION
FOR THE WEEKEND. HIGHS FRIDAY THROUGH SUNDAY WILL BE IN THE LOW TO
MID 80S...BUT DEW POINTS IN THE UPPER 50S AND LOW 60S WILL MAKE
THOSE READINGS FEEL MUCH MORE PLEASANT THAN THEY HAVE RECENTLY.

A WEAK AND MOISTURE STARVED FRONT APPROACHES THE REGION SATURDAY
MORNING...WITH BOTH THE GFS AND ECMWF SHOWING THE PRECIP FALLING
APART BEFORE IT REACHES THE FORECAST AREA. THIS IS LIKELY DUE TO
THE DRY AIR/RIDGING AT THE SURFACE. THERE IS SOME MID LEVEL
MOISTURE AND WEAK ENERGY WITH THE FRONT AS IT PASSES TO OUR NORTH
SO HAVE KEPT A SLIGHT CHANCE OF AN ISOLATED SHOWER IN THE FAR
NORTHERN COUNTIES. BUT DO NOT EXPECT MUCH MORE THAN AN INCREASE IN
SOME MID LEVEL CLOUDS ON SATURDAY FOR MOST AREAS.

SHOWER CHANCES RETURN TO THE REGION BY TUESDAY AS THE UPPER LEVEL
PATTERN BECOMES MORE ACTIVE. MODELS INDICATE THAT SEVERAL UPPER
LEVEL IMPULSES EMBEDDED IN THE NW FLOW WILL MOVE ACROSS EASTERN
KENTUCKY THROUGH THE END OF THE FORECAST PERIOD BRINGING INCREASED
SHOWER AND THUNDERSTORM CHANCES THROUGH THE END OF THE WORK WEEK.
TEMPERATURES (AND HUMIDITY) WILL INCREASE BACK INTO THE UPPER 80S
BY THE END OF THE PERIOD...WITH HEAT INDICES LIKELY SURPASSING THE
90 DEGREE MARK.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z THURSDAY NIGHT)
ISSUED AT 243 AM EDT THU JUL 30 2015

CONDITIONS WERE MOSTLY VFR AT THE START OF THE PERIOD. A
DETERIORATION TO IFR AND MVFR IS EXPECTED OVERNIGHT. IMPROVEMENT
BACK TO VFR SHOULD OCCUR ON THURSDAY MORNING. A SHOWER OR
THUNDERSTORM WILL BE POSSIBLE UP UNTIL A COLD FRONT MOVES THROUGH
FROM NW TO SE. THIS WILL HAPPEN BETWEEN ABOUT 09Z AND 16Z.

&&

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

$$

UPDATE...HAL
SHORT TERM...JP
LONG TERM...JVM
AVIATION...HAL


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