Area Forecast Discussion
Issued by NWS Jackson, KY

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000
FXUS63 KJKL 300040 AAA
AFDJKL

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE JACKSON KY
840 PM EDT FRI AUG 29 2014

.UPDATE...
ISSUED AT 840 PM EDT FRI AUG 29 2014

00Z SFC ANALYSIS SHOWS GENERAL HIGH PRESSURE OVER THE AREA WITH LOW
PRESSURE TO THE NORTHWEST. HOWEVER...THERE IS A WARM FRONT LIFTING
NORTHEAST THROUGH EASTERN KENTUCKY. THIS WAS THE GENESIS OF A FEW
SHOWERS AND THUNDERSTORMS DURING THE MID AND LATE AFTERNOON HOURS
THAT ARE JUST NOW DISSIPATING OVER THE NORTHERN PARTS OF THE CWA.
MOST PLACES DID STAY DRY TODAY SO THE THREAT OF WIDESPREAD FOG
FORMING LATER TONIGHT IS LOW...THOUGH FOR PLACES THAT DID SEE RAIN
AND THE DEEPER VALLEYS WILL LIKELY SEE AREAS OF FOG TOWARDS DAWN.
OTHERWISE...A QUIET NIGHT WILL BE HAD THROUGH EASTERN KENTUCKY WITH
CHANCES OF ADDITIONAL CONVECTION MINIMAL DESPITE THE NEARBY BOUNDARY.
HAVE UPDATED THE GRIDS TO REFLECT THIS WHILE ALSO ADJUSTING THE LOW
TEMPERATURES FOR A DECENT RIDGE TO VALLEY SPLIT ACROSS THE AREA.
FINALLY...TWEAKED THE NEAR TERM GRIDS PER THE LATEST OBS...TRENDS...
AND CONSSHORT GUIDANCE. THESE GRIDS HAVE BEEN SENT TO THE NDFD AND
WEB SERVERS WITH A ZFP AND HWO UPDATE TO FOLLOW ONCE THE LAST OF THE
CONVECTION FADES OVER THE NEXT HOUR OR SO.

&&

.SHORT TERM...(THIS EVENING THROUGH SATURDAY NIGHT)
ISSUED AT 357 PM EDT FRI AUG 29 2014

SURFACE HIGH PRESSURE IS CURRENTLY PARKED ACROSS NEW ENGLAND...WITH
ELONGATED SURFACE LOW PRESSURE ALIGNED ALONG THE PLAINS STATES. A
COLD FRONT EXTENDS SOUTHWEST FROM THE LOW DOWN NEAR THE OKLAHOMA
PANHANDLE...WITH A WARM FRONT DANGLING EAST SOUTHEAST DOWN INTO
EASTERN KENTUCKY. ALOFT...AN UPPER LEVEL LOW/TROUGH IS SPIRALING
THROUGH THE CENTRAL PLAINS...WITH A RETREATING UPPER LEVEL RIDGE
MOVING TOWARDS THE EASTERN SEABOARD. WARM AND HUMID CONDITIONS
PREVAIL ACROSS MOST OF EASTERN KENTUCKY...WITH SOME LOCATIONS
REPORTING IN THE LOWER 90S...WITH DEW POINTS RANGING FROM THE MID
60S TO THE LOWER 70S. DRIER AIR CAN BE FOUND DEEPER INTO SOUTH
CENTRAL KENTUCKY AND TENNESSEE...WHERE SOME DEW POINTS HAVE MIXED OUT
INTO THE 50S. ISOLATED SHOWERS AND THUNDERSTORMS HAVE POPPED UP NEAR
AND AROUND THE WARM FRONT CURRENTLY EASING ITS WAY TO THE NORTH.

THE MODELS REMAIN IN GOOD AGREEMENT THROUGH THE SHORT TERM...WITH THE
UPPER LEVEL LOW/TROUGH GRADUALLY SWINGING TOWARDS THE GREAT LAKES
REGION THROUGH SATURDAY NIGHT. AS DEEPER SOUTHWEST FLOW INCREASES
ACROSS THE MISSISSIPPI VALLEY IN RESPONSE TO THIS...A SHORT WAVE
TROUGH WILL MOVE OUT OF THE GULF REGION AND TRACK NORTHEAST INTO THE
OHIO VALLEY BY SATURDAY NIGHT...BRINGING A ROUND OF SHOWERS AND SOME
THUNDERSTORMS TO THE AREA.

FOR TONIGHT...EXPECT AN OVERALL DECREASE IN THE ISOLATED CONVECTION
ONCE AGAIN WITH THE LOSS OF HEATING...ALTHOUGH WITH THE SURFACE
BOUNDARY LINGERING IN THE AREA THROUGH ABOUT 02 TO 03Z...WILL HANG
ONTO A CORRIDOR OF ISOLATED POPS UNTIL THAT TIME. LIGHT SOUTHERLY
WINDS SHOULD KEEP THE FOG RESTRICTED TO THE DEEPER RIVER VALLEYS
TONIGHT...WITH SOME INCREASE IN HIGH CLOUDS TOWARDS DAWN.

FOR SATURDAY...THE FIRST HALF OF THE DAY LOOKS TO REMAIN DRY...WITH
TEMPERATURES LIKELY TOUCHING THE 90 DEGREE MARK IN SOME
LOCATIONS...ESPECIALLY EAST...WHERE THERE WILL BE LESS CLOUD COVER.
LATER IN THE DAY...DEEPER MOISTURE WILL BE ON THE INCREASE AS A
DECENT LOW LEVEL JET ENSUES ACROSS THE TENNESSEE VALLEY. THE BLENDED
12 HOUR POPS CAME IN A BIT LEANER OVERALL...HOWEVER WAS A BIT LEARY
TO BACK OFF TOO MUCH WITH SUCH DEEP MOISTURE ADVECTING IN LATE. FOR
NOW...MAINTAINED A GOOD GRADIENT...WITH HIGHER CHANCES IN THE
WEST...AND MUCH LESS IN THE EAST.

BY SATURDAY NIGHT...THE SHORT WAVE TROUGH WILL MOVE IN...BRINGING
A GOOD CHANCE OF MEASURABLE RAINS TO MOST LOCATIONS BY DAWN SUNDAY
MORNING. HAVE FOLLOWED SUIT WITH THE GUIDANCE AND INCREASED POPS TO
LIKELY FOR ALL BUT THE FAR EAST. INSTABILITY LOOKS TO BE ON THE
WEAKER SIDE AND OVERALL FORCING IS MODEST...SO HAVE MENTIONED JUST A
CHANCE OF THUNDER. PWATS INCREASE TO AROUND 2 INCHES DURING THIS
TIME FRAME...SO HEAVY RAINS STILL LOOK POSSIBLE...AND WILL CONTINUE
TO MENTION IN THE HWO.

.LONG TERM...(SUNDAY THROUGH FRIDAY)
ISSUED AT 357 PM EDT FRI AUG 29 2014

THE MODELS ARE STILL IN GOOD AGREEMENT WITH THE LARGE SCALE WEATHER
PATTERN AND SENSIBLE WEATHER ACROSS THE EASTERN CONUS TO BEGIN THE
PERIOD. THE DATA STILL STRONGLY SUGGESTS THAT A LARGE WELL DEFINED
UPPER LEVEL TROUGH WILL PUSH EASTWARD ACROSS THE GREAT LAKES AND
OHIO VALLEY REGIONS SUNDAY THROUGH MONDAY. AS THIS OCCURS...A LESS
WELL DEFINED SURFACE FRONT IS PROGGED TO ALSO MOVE ACROSS CENTRAL
AND EASTERN KENTUCKY...BRINGING WITH IT WIDESPREAD SHOWERS AND
THUNDERSTORMS. THIS BOUNDARY WILL BE ABLE TO TAP INTO A SIGNIFICANT
FEED OF GULF OF MEXICO MOISTURE...AND DUE TO THE SLOW MOVEMENT OF THE
FRONT...AS WELL AS TALL AND SKINNY CAPE PROFILES STILL APPEARING IN THE
FORECAST SOUNDINGS...ANY SHOWERS AND STORMS WILL BE EFFICIENT
RAINFALL PRODUCERS. THIS WILL ONCE AGAIN LEAD TO THE POTENTIAL FOR
LOCALLY HEAVY RAINFALL DURING THE DAY ON SUNDAY DURING PEAK HEATING.
ONCE THE INITIAL TROUGH EXITS TO OUR EAST MONDAY NIGHT...A SECOND
MUCH WEAKER ONE IS EXPECTED TO MOVE IN BEHIND IT. THIS IS WHERE THE
MODELS BECOME A BIT DISJOINTED WITH ONE ANOTHER. THE OVERALL VIEW IS
FOR PRECIPITATION CHANCES TO CONTINUE THROUGH THE REMAINDER OF THE
WORK WEEK FROM TUESDAY ONWARD. THE MAIN QUESTIONS WILL BE THE TIMING
AND THE EVOLUTION OF PRECIPITATION ASSOCIATED WITH THIS NEXT SYSTEM.
BASED ON ALL THIS...BY FAR THE BEST CHANCE FOR RAIN WILL BE SUNDAY
THROUGH MONDAY...WHICH IS THE TIME FRAME WITH THE HIGHEST PRECIP
CHANCES...WITH A MUCH LOWER CONFIDENCE PRECIP FORECAST AFTER MONDAY
NIGHT. WENT WITH GENERAL THUNDER CHANCES ACROSS THE BOARD DUE TO THE
AMOUNT OF INSTABILITY AND MOISTURE FEED SHOWING UP IN ALL THE MODEL
DATA. PRECIPITATION CHANCES MIGHT INCREASE SOME TOWARD THE END OF THE
WEEK PER THE LATEST RUN OF THE ECMWF. WITH THAT MODEL TYPICALLY BEING
THE MOST RELIABLE...THE SUPERBLEND MODEL DATA INGEST WAS ADJUSTED
TOWARD THE NEW ECMWF FOR THE THURSDAY/FRIDAY TIME FRAME.

TEMPERATURES DURING THE PERIOD LOOK TO BE AT OR EVEN SLIGHTLY ABOVE
NORMAL BOTH DURING THE DAY AND NIGHT TIME PERIODS AS PERSISTENT
SOUTHERLY TO SOUTHWESTERLY FLOW SETS UP ACROSS THE REGION. HIGHS
EACH DAY SHOULD TOP OUT IN THE MID TO UPPER 80S...WITH NIGHTLY LOWS
COMING IN AROUND 70. THE ONE EXCEPTION TO THIS RULE WILL BE
SUNDAY...WHEN THE MERCURY IS EXPECTED TO ONLY MAKE IT TO AROUND 80
DEGREES...DUE TO THE INFLUENCE OF WIDESPREAD CLOUD COVER AND
PRECIPITATION.

&&

.AVIATION...(FOR THE 00Z TAFS THROUGH 00Z SATURDAY EVENING)
ISSUED AT 825 PM EDT FRI AUG 29 2014

WITH THE CONVECTION DISSIPATING THIS EVENING...EXPECT SOME IFR OR
WORSE FOG DEVELOPMENT OVERNIGHT WITHIN THE DEEPER RIVER VALLEYS...BUT
LIKELY STEERING CLEAR OF THE TAF SITES LIKE THE BULK OF THE RAIN
DURING THE PAST 24 HOURS. HOWEVER...HAVE INCLUDED A TEMPO FOR MVFR
FOG AT SJS AND LOZ SINCE THEY SAW AT LEAST A TRACE OF RAIN THIS PAST
EVENING. CLOUDS WILL ALSO BE ON THE INCREASE LATE TONIGHT AND INTO
THE DAY ON SATURDAY OUT AHEAD OF AN APPROACHING UPPER LEVEL SYSTEM.
THE CONVECTIVE THREAT ASSOCIATED WITH THIS SYSTEM LOOKS TO HOLD OFF
UNTIL LATER SATURDAY AFTERNOON FROM WEST TO EAST WHEN VCTS WAS ADDED
TO THE TAFS. WINDS WILL GENERALLY BE OUT OF THE SOUTH TO SOUTHWEST AT
5 TO 10 KTS THROUGH THE PERIOD.

&&

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

$$

UPDATE...GREIF
SHORT TERM...GEOGERIAN
LONG TERM...AR
AVIATION...GREIF



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