Area Forecast Discussion
Issued by NWS Jackson, KY

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000
FXUS63 KJKL 301735
AFDJKL

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JACKSON KY
135 PM EDT SAT AUG 30 2014

.UPDATE...
ISSUED AT 135 PM EDT SAT AUG 30 2014

ONCE AGAIN THE FORECAST AS ON TRACK. THE GRIDS WERE UPDATED USING THE
LATEST OBSERVATIONAL DATA. THE FORECAST TEXT PRODUCT WAS IN GOOD
SHAPE AS IS WITH NO UPDATE ISSUED.

UPDATE ISSUED AT 1050 AM EDT SAT AUG 30 2014

UPDATED THE HOURLY GIRDS WITH MOST RECENT OBSERVATIONS. FOG THAT
FORMED EARLIER THIS MORNING HAS SINCE DISSIPATED. CLOUD COVER WILL BE
ON THE INCREASE THROUGHOUT THE DAY AS A WEATHER SYSTEM APPROACHES
FROM THE WEST. ISOLATED TO SCATTERED SHOWERS AND THUNDERSTORMS ARE
STILL ON TAP FOR LATER TODAY. THE FORECAST IN GENERAL WAS ON TRACK
WITH NO MAJOR CHANGES NECESSARY.

UPDATE ISSUED AT 735 AM EDT SAT AUG 30 2014

HOURLY GRIDS HAVE BEEN FRESHENED UP BASED ON RECENT OBSERVATIONS. ANY
LINGERING RIVER VALLEY FOG SHOULD LIFT AND DISSIPATE THROUGH 9 AM
EDT. OTHERWISE...MOISTURE WILL INCREASE FROM THE SOUTH AND SOUTHWEST
TODAY AND CLOUD COVER WILL ALSO...ESPECIALLY FROM LATE MORNING INTO
THE AFTERNOON. DAYTIME HEATING AND AN APPROACHING DISTURBANCE WILL
LEAD TO AT LEAST ISOLATED TO SCATTERED SHOWERS AND THUNDERSTORMS BY
MID TO LATE AFTERNOON AND CONTINUING INTO THE EVENING. RECENT HRRR
RUNS AS WELL AS THE RECENT GFS AND NAM RUNS SUPPORT THIS.

&&

.SHORT TERM...(TODAY THROUGH SUNDAY)
ISSUED AT 415 AM EDT SAT AUG 30 2014

AN ILL DEFINED WARM FRONT IS GRADUALLY LIFTING NORTH AND NORTHEAST ACROSS
THE NORTHERN AND EASTER PART OF THE REGION. CONVECTION FROM EARLIER
IN THE OVERNIGHT HOURS DISSIPATED...BUT SOME MID CLOUDS ARE LEFT
BEHIND ACROSS THOSE AREAS. PATCHY VALLEY FOG HAS DEVELOPED IN A FEW
SPOTS EARLY THIS MORNING...BUT VIS REDUCTIONS HAVE NOT BEEN ALL THAT
MUCH. AT MID AND UPPER LEVELS...A RIDGE OF HIGH PRESSURE IS CENTERED
OVER THE SOUTHEASTERN CONUS WITH A TROUGH EXTENDING SOUTH FROM THE
UPPER MIDWEST TO THE MS VALLEY REGION BETWEEN THE SOUTHEAST RIDGE AND
RIDGING OVER THE DESERT SOUTHWEST. A SHORTWAVE WAS ALSO LOCATED OVER
EAST TX/WESTERN LA EARLY THIS MORNING. THIS PATTERN PUTS THE REGION
IN DEEP SOUTHERLY TO SOUTHWESTERLY FLOW WITH EMBEDDED PASSING
SHORTWAVES.

THE TROUGH WILL GRADUALLY WORK INTO THE GREAT LAKES REGION AND LOWER
OH VALLEY REGION TODAY AND INTO TONIGHT...AND PICK UP THE SOUTHERN
SHORTWAVE AND SEND IT INTO THE TN AND LOWER OH VALLEY REGION BY LATE
TONIGHT AND THEN SLOWLY ACROSS THE AREA ON SUNDAY. THE DEEP SOUTHERLY
FLOW WILL BRING A PLUME OF VERY DEEP MOISTURE NORTH INTO THE OH AND
TN VALLEY REGION LATER TONIGHT AND LINGERING INTO THE DAY ON SUNDAY.
PWS ARE PROGGED TO CLIMB TOWARD TWO INCHES BY LATE THIS EVENING AND
LINGER NEAR THAT LEVEL INTO SUNDAY EVENING. HOWEVER...THE DEEPER
MOISTURE WILL START TO DECREASE LATE IN THE PERIOD AS THE DISTURBANCE
BEGINS TO EXIT.

AFTER ANY EARLY MORNING VALLEY FOG DISSIPATES WITHIN A COUPLE HOURS
AFTER SUNSET...A PERIOD OF SUNSHINE WITH SOME MID AND HIGH LEVEL
CLOUDS IS ANTICIPATED FOR MUCH OF THE MORNING...AND LINGERING INTO
THE EARLY AFTERNOON ACROSS THE FAR NORTHEAST. CONVECTION WITH
SHORTWAVE WORKING TOWARD THE LOWER OH VALLEY REGION SHOULD DEVELOP
OR APPROACH THE SOUTHWESTERN AND SOUTHERN PARTS OF THE AREA BY EARLY
TO MID AFTERNOON. ADDITIONAL CONVECTION WILL BE POSSIBLE AS DAYTIME
HEATING OF THE INCREASINGLY MOIST AIR MASS OCCURS. THE MOISTURE
INCREASE SHOULD OCCUR FIRST ACROSS THE SOUTH AND WEST...SO CHANCES
FOR CONVECTION LATER TODAY WILL BE BEST IN THOSE AREAS. DRIER AIR AND
AN INITIAL DOWNSLOPE COMPONENT TO THE WINDS WILL LESSEN CHANCES FOR
CONVECTION ACROSS THE FAR EAST AND SOUTHEAST.

AS THE SHORTWAVE(S) TRACK INTO KY...THE CHANCES FOR CONVECTION WILL
INCREASE ACROSS THE JKL CWA TONIGHT AS THEY INTERACT WITH THE DEEP
MOISTURE IN PLACE. THIS SCENARIO WILL BE INSTABILITY AND UPPER LEVEL
DRIVEN AND POSSIBLY MESOSCALE DRIVEN FROM OUTFLOWS WITH NO REAL SFC
FEATURES. THE PW WILL BE AROUND THE 99TH PERCENTILE SO ANY
THUNDERSTORM IS EXPECTED TO HAVE HIGH RAINFALL RATES IF CONVECTION
WERE TO TRAIN OR MOVE REPEATEDLY ACROSS THE SAME LOCATIONS HEAVY RAIN
AND HIGH WATER WOULD BE A CONCERN. THE MODEL CONSENSUS STILL FOCUS
THE BEST CHANCES FOR RAIN TONIGHT ACROSS THE WEST AND NORTHWEST. THE
TRACK OF THE SHORTWAVE(S) THEN BRINGS THE FOCUS FOR CONVECTION A BIT
FURTHER SOUTH AND EAST ON SUNDAY. OVERALL...QPF FOR THE EVENT SHOULD
BE HIGHEST ACROSS THE WEST AND NORTH...AND ON AVERAGE THE LEAST NEAR
THE VA BORDER.

ABOVE NORMAL TEMPERATURES ARE EXPECTED AGAIN TODAY...WITH TEMPS
NEARING 90 AGAIN IN SOME LOCATIONS...ESPECIALLY NORTH AND EAST. THE
INCREASE IN CLOUD COVER SHOULD KEEP THE SOUTHWESTERN LOCATIONS NEAR
THE SAME...IF NOT A BIT COOLER THAN THE REST OF THE AREA TODAY. CLOUD
COVER AND THE DEEP MOISTURE WILL LEAD TO ABOVE NORMAL MIN TEMPS
TONIGHT. HOWEVER...WITH ANTICIPATED CLOUD COVER...TEMPERATURES SHOULD
AVERAGE NEAR NORMAL...IT NOT A BIT BELOW NORMAL ON SUNDAY WHERE
SHOWERS AND THUNDERSTORMS ARE THE MOST PERSISTENT.

.LONG TERM...(SUNDAY NIGHT THROUGH FRIDAY)
ISSUED AT 241 AM EDT SAT AUG 30 2014

MODELS ARE IN OK AGREEMENT INTO THE EARLY PART OF THE WEEK...BUT
DIFFERENCES EMERGE AROUND A COLD FRONT DROPPING IN FROM THE NORTH
AROUND MIDWEEK. THESE DIFFERENCES MAINLY REVOLVE AROUND TIMING AND
EXACTLY WHERE THE BOUNDARY STALLS OR ENDS UP BY WEDNESDAY.
THUS...FORECAST CONFIDENCE IS DIMINISHED BEYOND MONDAY. HOWEVER...AS
IT LOOKS NOW...PRECIPITATION CHANCES THROUGH NEXT WEEK WILL HAVE A
DIURNAL TREND...PEAKING IN THE LATE AFTERNOON HOURS...WITH A MINIMUM
OVERNIGHT.

STARTING OFF SUNDAY NIGHT...PRECIPITATION WITH THE SHORTWAVE TROUGH
ON SUNDAY WILL COME TO AN END SUNDAY EVENING...WITH THE AREA DRYING
OUT OVERNIGHT. NOT MUCH ON TAP FOR MONDAY WITH LACK OF ANY
SUBSTANTIAL SYSTEM. WE WILL PROBABLY JUST SEE A FEW ISOLATED SHOWERS
OR STORMS POP UP DURING THE AFTERNOON...BUT COVERAGE SHOULD BE VERY
LOW. SAME WILL HOLD FOR TUESDAY...ALTHOUGH THE AFOREMENTIONED COLD
FRONT MAY ARRIVE FROM THE NORTH IF THE GFS IS CORRECT LATE IN THE
DAY. THE ECMWF IS SLOWER AND HOLDS THE FRONT TO OUR NORTH THROUGH
THE DAY. BY TUESDAY NIGHT AND WEDNESDAY THE COLD FRONT SHOULD MAKE
ITS WAY ACROSS THE AREA. SHOWER/STORM COVERAGE ALONG THE FRONT MAY
BE TIED MORE TO AVAILABLE INSTABILITY...WITH THE HIGHEST COVERAGE
TUESDAY EVENING AND AGAIN WEDNESDAY AFTERNOON/EVENING.
HOWEVER...AGAIN CONFIDENCE IS LOW AS THE GFS TAKES THE BOUNDARY
SOUTH OF US AND WOULD SUPPORT DRIER WEATHER FOR TUESDAY NIGHT AND
WEDNESDAY. NO SUBSTANTIAL SYSTEMS THROUGH THE REMAINDER OF THE
EXTENDED...BUT GIVEN THE WARMTH AND HUMIDITY...ISOLATED
SHOWERS/STORMS WILL BE POSSIBLE EACH AFTERNOON/EVENING THROUGH THE
END OF THE WEEK. TEMPERATURES WILL REMAIN NEAR OR SLIGHTLY ABOVE
NORMAL THROUGH THE WHOLE WEEK.

&&

.AVIATION...(FOR THE 18Z TAFS THROUGH 18Z SUNDAY AFTERNOON)
ISSUED AT 135 PM EDT SAT AUG 30 2014

THE AVIATION FORECAST WAS FAIRLY STRAIGHT FORWARD. THE LATEST MODEL
DATA CONTINUES TO INDICATE THAT SCATTERED SHOWERS AND STORMS WILL
BEGIN FORMING AND MOVING INTO EASTERN KENTUCKY THIS AFTERNOON. THE
COVERAGE OF THE SHOWERS AND STORMS SHOULD BECOME EXTENSIVE ENOUGH TO
AFFECT THE TAF SITES BETWEEN 19 AND 21Z TODAY. THE BEST COVERAGE OF
PRECIPITATION LOOKS TO BE DURING THE OVERNIGHT HOURS AND ALL DAY ON
SUNDAY. LOCALLY HEAVY RAINFALL AND LIGHTNING WILL BE THE PRIMARY
THREATS WITH ANY SHOWERS AND STORMS. FOG SHOULD BE KEPT TO A MINIMUM
DUE TO THE PERSISTENT RAIN AND WIND ASSOCIATED WITH THE SHOWERS AND
STORMS. VFR CONDITIONS WILL PREVAIL UNTIL THE SHOWERS AND STORMS MOVE
ACROSS THE TAF SITES. MVFR CONDITIONS ARE EXPECTED WITH THE SHOWER
AND STORM ACTIVITY ALONG WITH PERHAPS A LITTLE BIT OF FOG.

&&

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

$$

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






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