Area Forecast Discussion
Issued by NWS Jackson, KY

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000
FXUS63 KJKL 250735
AFDJKL

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JACKSON KY
335 AM EDT SAT APR 25 2015

.UPDATE...
ISSUED AT 202 AM EDT SAT APR 25 2015

WITH EXTENSIVE CLOUD COVER IN PLACE...TEMPS HAVE NOT DROPPED OFF
AS QUICKLY AS WAS FORECAST. HAVE RAISED OVERNIGHT FORECAST MIN
TEMPS A BIT...ESPECIALLY IN EASTERN VALLEYS.

UPDATE ISSUED AT 1050 PM EDT FRI APR 24 2015

DID AN UPDATE TO FINE TUNE THE POPS AND WX THROUGH THE REST OF THE
NIGHT BASED ON THE NEWEST HRRR AND NAM12 GUIDANCE AS WELL AS
CURRENT RADAR/OBS. ALSO MATCHED UP THE HOURLY T AND TD GRIDS PER
THE LATEST OBS AND TRENDS...WHERE A 5 DEGREE OR SO RIDGE TO VALLEY
SPLIT CURRENTLY EXISTS IN THE EAST. THESE GRIDS HAVE BEEN SENT TO
THE NDFD AND WEB SERVERS...ALONG WITH THE ISSUANCE OF A FRESHENED
SET OF ZONES.

UPDATE ISSUED AT 745 PM EDT FRI APR 24 2015

23Z SFC ANALYSIS SHOWS HIGH PRESSURE CLINGING ON IN THE FAR EAST
IN THE FACE OF AN APPROACHING AREA OF LOW PRESSURE...POISED TO
BRING SVR WX TO KY LATER ON SATURDAY...FROM THE WEST. THIS
WESTERN LOW/S WARM FRONT WILL SWING TOWARD THE AREA BY DAWN...
AFFECTING THE FAR SOUTHWEST INITIALLY THEN LIFTING DEEPER INTO
EAST KENTUCKY THROUGH MIDDAY SATURDAY. THE PCPN WILL HAVE A TOUGH
TIME REACHING THE GROUND ACROSS THE AREA THROUGH THE BULK OF THE
NIGHT AS THE VERY DRY LOWER ATMOSPHERE ONLY SLOWLY SATURATES...
DESPITE THE HRRR/NAM12 INDICATIONS. IN THIS ENVIRONMENT...EXPECT
THE EASTERN VALLEYS TO DROP OFF QUICKLY FOLLOWING SUNSET...EVEN
WITH THE THIN HIGH CLOUDS NOW IN PLACE OVERHEAD. ELSEWHERE...
TEMPERATURES WILL STAY UP THROUGH THE NIGHT...MUCH WARMER THAN
LAST NIGHT. HAVE UPDATED THE FORECAST TO NUDGE TEMPS IN THE
EASTERN VALLEYS DOWN A BIT...BUT EXPECT THEM TO MIX OUT BY DAWN AS
THE AIR SATURATES AND SHOWERS PUSH OVER THIS PART OF THE STATE. IN
ADDITION TO THE SEVERE THREAT FOR SATURDAY...THE LATEST MODEL RUNS
CONTINUE TO INDICATE THAT THERE IS ALSO A POTENTIAL FOR EXCESSIVE
RAINFALL DEPENDING ON THE TRACKS OF THE INDIVIDUAL CELLS AND/OR AN
MCS TRACKING ACROSS THE CWA IN THE AFTERNOON/EVENING THAT
CERTAINLY LOOKS POSSIBLE. THESE UPDATED GRIDS HAVE BEEN SENT TO
THE NDFD AND WEB SERVERS.

&&

.SHORT TERM...(THIS EVENING THROUGH SATURDAY NIGHT)
ISSUED AT 350 PM EDT FRI APR 24 2015

CURRENT CONDITIONS ACROSS THE AREA FEATURE SURFACE HIGH PRESSURE
SLOWLY SLIDING OFF TO THE EAST TODAY. MID AND UPPER LEVEL CLOUD
COVER AT THIS TIME IS BEGINNING TO STREAM INTO EASTERN KENTUCKY
THIS EVENING. THIS IS AHEAD OF A DEVELOPING LOW PRESSURE SYSTEM
OUT WEST OVER THE CENTRAL PLAINS. CLOUD COVER OVER THE AREA WILL
LIKELY KEEP TEMPERATURES OVERNIGHT NEARLY UNIFORM WITH SOUTHERLY
WARM AIR MOVING INTO THE AREA THROUGH THE NIGHT. AT THIS TIME
OVERNIGHT...THE SURFACE LOW SLIDES EAST AS A WARM FRONT DEVELOPS
IN THE LOWER MS VALLEY AND MOVING NORTHEAST. THIS WILL BRING
SHOWERS INTO EASTERN KENTUCKY BY MIDNIGHT OR SHORTLY AFTERWARD.

HEADING INTO THE PREDAWN HOURS SATURDAY MORNING...THE MAIN SURFACE
LOW BEGINS TO MOVE INTO THE MID MS RIVER VALLEY AND INTO THE
MIDWEST WITH SOME INSTABILITY BEGINNING TO ENTER THE SOUTHWESTERN
COUNTIES AND THIS MAY LEAD TO A FEW EARLY NON SEVERE STORMS AND
MAY NEED TO ADD THUNDER TO THE TONIGHT PERIOD OF THE HWO. HEADING
INTO THE DAY ON SATURDAY...AFTER EARLIER RAINFALL HAS MOVED
THROUGH...SOME CLEARING SKIES AND RECOVERING ENERGY AND
DESTABILIZATION WILL THEN OCCUR WITH MOST UNSTABLE CAPE AROUND
1000 TO 1500 J/KG OVER SOUTHEASTERN KENTUCKY BY THE 18Z TIME
FRAME. THIS ALSO WITH SOME 60 KNOT SFC TO 6KM BULK SHEAR WILL BE
ENOUGH FOR SOME ROTATING STORMS TOMORROW AFTERNOON. DUE TO THIS
THREAT SPC HAS PUT THE SOUTHERN AREA IN AN ENHANCED THREAT OF
SEVERE WEATHER AND HAVE PUT THIS THREAT IN THE HWO AND MAY NEED AN
SPS TO HIGHLIGHT THE THREAT IN DETAIL. THE ONLY THREAT THAT IS A
BIT QUESTIONABLE TOMORROW WILL BE THE FLASH FLOOD THREAT. THOUGH
THE LAST HEAVY RAINFALL WAS LONG ENOUGH AGO THAT MOST PLACES HAVE
BEEN ALLOWED TO DRAIN AND DRY OUT. AS WELL...GREEN HAS GONE INTO
FULL SWING ACROSS THE AREA ALLEVIATING THE RUNOFF POTENTIAL.
HOWEVER...THE DISCRETE SUPER CELL POTENTIAL WILL ADD TO THE THREAT
OF FLASH FLOODING AS WELL AS IF AN MCS DEVELOPS BY LATE IN THE
EVENING ON SATURDAY. MAY NEED TO EVALUATE THIS DURING THE NEXT
MODEL RUN.

HEADING INTO SATURDAY EVENING...THE WARM FRONT MOVES THROUGH TO
THE NORTHEAST AND THEN THE SURFACE LOW TRACKS RIGHT ACROSS EASTERN
KENTUCKY WITH ANOTHER STRONG SHOT OF RAINFALL WHICH MAY BE ENOUGH
TO INITIATE THE FLASH FLOOD THREAT. HAVE ADJUSTED THE QPF FOR THE
00Z TO 06Z SUNDAY NIGHT PERIOD FOR THIS RAINFALL. RAINFALL AMOUNTS
WILL BE LESSENING BY 06Z TO 12Z RANGE SUNDAY NIGHT AS THE EVENT
WILL BE WINDING DOWN. FOR NOW...WILL HIGHLIGHT THE SEVERE AND
FLOOD THREAT IN THE HWO AND MAY NEED AN SPS TO FURTHER HIGHLIGHT
THIS. THE ZFP WILL HAVE SEVERE POTENTIAL AND HEAVY RAINFALL
MENTIONED AS WELL.

.LONG TERM...(SUNDAY NIGHT THROUGH FRIDAY)
ISSUED AT 335 AM EDT SAT APR 25 2015

THE MODELS WERE IN GOOD AGREEMENT IN THE EXTENDED. THE PERIOD IS
SET TO BEGIN WITH A LARGE RIDGE OF HIGH PRESSURE MOVE OUT OF THE
NORTH CENTRAL PLAINS AND ACROSS THE LOWER GREAT LAKES AND OHIO AND
TENNESSEE VALLEY REGIONS SUNDAY NIGHT THROUGH TUESDAY. THE PATTERN
IS THEN FORECAST TO CHANGE TUESDAY NIGHT AND WEDNESDAY...AS BOTH
NORTHERN AND SOUTHERN STREAM WEATHER SYSTEMS MAKE THEIR WAY ACROSS
THE GREAT LAKES AND GULF COAST REGIONS. THE SOUTHERN STREAM SYSTEM
APPEARS TO BE THE STRONGER OF THE TWO...AND THEREFORE WOULD HAVE
TO GREATER INFLUENCE ON AREA WEATHER MID WEEK. AS IT STANDS...A
ROUGHLY 60 40 BLEND OF THE ECMWF AND GFS MODELS WAS USED TO CREATE
THE FORECAST FROM TUESDAY NIGHT ONWARD. THE SOUTHERN STREAM
TROUGH IS PROGGED TO BRING MOISTURE OFF THE GULF OF MEXICO
NORTHWARD INTO CENTRAL AND EASTERN KENTUCKY WEDNESDAY AND
WEDNESDAY NIGHT. AS THIS OCCURS...THE NORTHERN STREAM SYSTEM IS
FORECAST TO DIVE SOUTHWARD AND PHASE WITH THE TENNESSEE VALLEY
SOUTHEASTERN CONUS LOW. THE GFS DOES DIFFER SLIGHTLY FROM THE
ECMWF MODEL DURING THIS PERIOD...AS ITS NORTHERN STREAM LOW PUSHES
ON EASTWARD INTO NEW ENGLAND...AS OPPOSED TO PHASING WITH THE
SOUTHERN SYSTEM...AS THE ECMWF IS DEPICTING. THAT BEING
SAID...THIS IS WHERE THE USUALLY MORE CONSISTENT ECMWF MODEL
SOLUTION WAS FAVORED. THERE WILL BE A CHANCE OF RAIN IN THE
FORECAST FOR THE ENTIRE AREA FROM LATE TUESDAY NIGHT THROUGH
THURSDAY NIGHT. HOWEVER...DUE TO THE DIFFERING MODEL
SOLUTIONS...DECIDED TO STAY WITH SLIGHT CHANCE TO CHANCE
POPS...WITH 40 BEING THE HIGH END DURING THE WET PERIOD. FRIDAY
AND FRIDAY NIGHT LOOK TO BE DRY AS THE SOUTHERN STREAM WEATHER
SYSTEM EXITS TO OUR EAST AND ANOTHER RIDGE OF HIGH PRESSURE BUILDS
ACROSS THE SOUTHERN AND SOUTHEASTERN CONUS.

TEMPERATURES NEXT WEEK WILL LIKELY BE BELOW NORMAL THROUGH
THURSDAY...DUE TO THE INFLUENCE OF CLOUD COVER AND PRECIPITATION
AND THE FACT THAT THIS WEEKENDS TEMPERATURES WILL ALSO REMAIN WELLBELOW
NORMAL DUE WIDESPREAD CLOUD COVER AND PRECIPITATION. WHAT THIS
AMOUNTS TO IS THE ATMOSPHERE WILL STARTING OFF BEHIND THE EIGHT
BALL TO START THE WEEK TEMPERATURE WISE...MAKING IT DIFFICULT FOR
THINGS TO WARM UP AS MUCH AS NORMAL DUE TO THE SHORT BREAK BETWEEN
WEATHER SYSTEMS. HIGHS ON FRIDAY SHOULD BE RIGHT AROUND NORMAL
ACROSS THE ENTIRE AREA.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z SATURDAY NIGHT)
ISSUED AT 202 AM EDT SAT APR 25 2015

VFR CONDITIONS WERE PRESENT AT TAF ISSUANCE...BUT WILL DEGRADE TO
MVFR FROM SW TO NE BETWEEN ABOUT 06Z AND 14Z AS RAIN DEVELOPS. IFR
IS ALSO EXPECTED AT TIMES THROUGH EARLY AFTERNOON. STEADY
PRECIPITATION WILL TAPER OFF FROM SW TO NE DURING THE LATE MORNING
AND EARLY AFTERNOON...AND WILL BE REPLACED BY SCATTERED SHOWERS
AND THUNDERSTORMS. THEY WILL BECOME MORE NUMEROUS LATE IN THE DAY
AND THIS EVENING. SOME LOCATIONS MAY DESCEND BACK TO IFR WITH THE
SHOWERS AND STORMS THIS EVENING. SOME OF THESE STORMS COULD
PRODUCE HAIL AND HIGH WINDS.


&&

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

$$

UPDATE...HAL
SHORT TERM...SHALLENBERGER
LONG TERM...AR
AVIATION...HAL


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