Area Forecast Discussion
Issued by NWS Jackson, KY

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FXUS63 KJKL 030630 AAA
AFDJKL

AREA FORECAST DISCUSSION...UPDATED
NATIONAL WEATHER SERVICE JACKSON KY
230 AM EDT MON AUG 3 2015

.UPDATE...
ISSUED AT 200 AM EDT MON AUG 3 2015

DID A QUICK UPDATE TO THE GRIDS MAINLY TO JUST TO TOUCH UP THE
T/TD GRIDS PER THE LATEST OBS AND TRENDS. THESE HAVE BEEN SENT TO
THE NDFD AND WEB SERVERS.

UPDATE ISSUED AT 1125 PM EDT SUN AUG 2 2015

UPDATED THE GRIDS TO FINE TUNE THE OVERNIGHT LOWS...INFUSE SOME OF
THE LATEST SHORTBLEND DATA...AND ACCOUNT FOR THE RIDGE TO VALLEY
TEMPERATURE SPLIT. THESE HAVE BEEN TWEAK PER THE LATEST OBS AND
TRENDS. UPDATED GRIDS HAVE BEEN SENT TO THE NDFD AND WEB SERVERS.

UPDATE ISSUED AT 712 PM EDT SUN AUG 2 2015

BROAD AREA OF HIGH PRESSURE REMAINS IN CONTROL ACROSS MUCH OF THE
OHIO AND TENNESSEE VALLEY INCLUDING EASTERN KY THIS EVENING. THIS
IS LEADING TO MOSTLY CLEAR SKIES ACROSS MUCH OF THE REGION WITH A
FEW LOCATIONS STILL SEEING SOME FAIR WEATHER CU. RIGHT NOW
FORECAST REMAINS ON TRACK WITH SOME MINOR ADJUSTMENTS TO LATEST
OBS AND TRENDS.

&&

.SHORT TERM...(THIS EVENING THROUGH MONDAY NIGHT)
ISSUED AT 330 PM EDT SUN AUG 2 2015

AFTERNOON SURFACE ANALYSIS SHOWS A BROAD AREA OF SURFACE HIGH
PRESSURE CENTERED ALONG THE KY/WV BORDER. THIS IS ALONG FOR MOSTLY
SUNNY TO SUNNY SKIES ACROSS ALL OF EASTERN KY THIS AFTERNOON.
THERE ARE A FEW DIURNALLY DRIVEN CU SHOWING UP ON VIS SAT...BUT
THESE ARE FAIR WEATHER CU. THIS WILL MAKE FOR A QUIET AND CALM
NIGHT ACROSS EASTERN KY WITH THAT WILL ALSO COME THE FOG
POTENTIAL OVERNIGHT. THINK THIS WILL BE SIMILAR TO WHAT WE HAVE
SEEN THE PAST COUPLE OF NIGHTS WITH MOSTLY RIVER VALLEYS AND
LOCATIONS CLOSER TO LARGER BODIES OF WATER SEEING THE BETTER FOG
POTENTIAL. THEREFORE ADJUSTED FORECAST GRIDS IN THAT DIRECTION.
THIS HIGH WILL GENERALLY SHIFT EAST OVERNIGHT INTO EARLY MONDAY.

NOW FOR MONDAY WE ARE CONTINUING TO WATCH A COLD FRONT TO THE NW
THAT WILL EVENTUALLY WORK SOUTH AND EAST INTO THE REGION IN THE
LATER HALF OF THE PERIOD. ONGOING CONVECTION ACROSS OHIO WILL
LIKELY DISSIPATE AS IT MOVES SOUTH AND EAST. THEREFORE STILL
THINK MUCH OF THE MORNING INTO THE EARLY AFTERNOON WILL REMAIN DRY
ON MONDAY. OVERALL SETUP WE HAVE THE AFOREMENTIONED COLD
FRONT...WHILE THE ATTENDANT LOW PRESSURE WILL BE LOCATED WELL
NORTHEAST ACROSS NORTHERN QUEBEC. THE 500MB LOW WILL BE LOCATED
JUST TO THE EAST OF THE LOW PRESSURE CENTER IN CANADA. WHILE SOME
SPOKES OF ENERGY WILL ROLE THROUGH THE LARGER CLOSED LOW THESE
WILL BE MORE PRONOUNCED ACROSS THE MID ATLANTIC. THEREFORE WE WILL
BE ON THE FAR SOUTHERN EXTENT OF THE BETTER LIFTING FOR ASCENT.
HOWEVER CANNOT DENY THE BOUNDARY BEING IN AND NEAR TO THE REGION
PROVIDING SOME AMOUNT OF LIFT. THAT SAID WE WILL STILL SEE
INCREASED SW FLOW IN RESPONSE THE FRONT MOVING SOUTHEAST INTO THE
REGION...THEREFORE WARM AND MOIST AIR WILL CREEP BACK IN GIVING
WAY TO A REASONABLY UNSTABLE ENVIRONMENT ACROSS PORTIONS OF
EASTERN KY. LOOKING AT FORECAST SOUNDINGS THERE IS ALSO REASONABLY
AMOUNT OF DRY MID LEVEL AIR AND STEEP 0-3 KM LAPSE RATES NEAR AND
ABOVE 8.0 C/KM IN THE AFTERNOON PARTICULARLY ALONG AND NORTH OF
THE I64 CORRIDOR. THIS IS LEADING TO DCAPE VALUES NEAR AND ABOVE
1000 J/KG...SO ANY STORMS THAT DO DEVELOP WILL HAVE THE POTENTIAL
FOR STRONG GUSTY WINDS DUE TO MOMENTUM TRANSFER. RIGHT NOW NOT
SOLD ON ANY SEVERE HAIL POTENTIAL GIVEN HIGHER FREEZING LEVELS AND
WARM TEMPS IN PLACE. THE WIND THREAT SEEMS MOST LIKELY GIVEN BOTH
CLIMATOLOGY AND OVERALL CIPS ANALOGS. THE FACT THAT THE BETTER
LIFT AND SUPPORT WILL BE NORTHEAST OF THE REGION SPC HAS
TRANSLATED THE SLIGHT RISK NORTHEAST OUT OF EASTERN KY...BUT AREAS
GENERALLY ALONG AND NORTH OF THE MOUNTAIN PARKWAY REMAIN IN A
MARGINAL RISK MONDAY. THEN THUNDERSTORMS ARE EXPECTED TO DECREASE
IN INTENSITY AND COVERAGE AS WE MOVE INTO THE NIGHT.

.LONG TERM...(TUESDAY THROUGH SUNDAY)
ISSUED AT 444 PM EDT SUN AUG 2 2015

MODELS SHOW A STALLED FRONTAL BOUNDARY NEAR THE SOUTHERN PORTION
OF THE JKL FORECAST AREA AS THE PERIOD STARTS. IT WILL BEGIN TO
LIFT NORTH TUESDAY THROUGH WEDNESDAY. WARM AIR ADVECTION AND GENERAL
CONVERGENCE IN THE VICINITY OF THE FRONT COULD LEAD TO
SHOWERS/THUNDERSTORMS...BUT TRYING TO TIME THEM AT THIS STAGE
WOULD BE FRUITLESS. THE HIGHEST PROBABILITY OF RAIN APPEARS TO BE
FROM WEDNESDAY NIGHT THROUGH THURSDAY...OR POSSIBLY THURSDAY
NIGHT. DURING THIS TIME...MODELS SHOW MORE SIGNIFICANT UPPER
LEVEL SUPPORT AS WAVES MOVING THROUGH AN EASTERN CONUS TROUGH
CAUSE THE TROUGH TO AMPLIFY OVER OUR AREA. MODELS AGREE ON THE
GENERAL SCENARIO... BUT NOT THE DETAILS OF THE IMPULSES TRAVELING
THROUGH. RAIN WOULD APPEAR TO BE A GOOD BET DURING THIS TIME
FRAME...BUT THE CONFIDENCE IN ANY GIVEN 12 HOUR BLOCK IS NOT
TERRIBLY HIGH. PEAK 12 HOUR POPS IN THE 50-60 PERCENT RANGE ARE
BEING USED AT THIS POINT...BUT THIS WILL PROBABLY INCREASE AT A
LATER TIME. A COLD FRONT LOOKS POISED TO MOVE THROUGH THURSDAY
NIGHT AND ALLOW A DRIER AIR MASS TO TRY TO MOVE IN. HOWEVER...
MODELS HAVE SHOWN SOME INCONSISTENCY CONCERNING HOW LONG THE UPPER
TROUGH HANGS OVER THE AREA AT THE END OF THE WEEK. HAVE HELD ONTO
SLIGHT CHANCE POPS THROUGH THE WEEKEND UNTIL THE SCENARIO BECOMES
MORE CLEAR.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z MONDAY NIGHT)
ISSUED AT 230 AM EDT MON AUG 3 2015

A BROAD AREA OF HIGH PRESSURE WILL REMAIN IN CONTROL OF THE
WEATHER ACROSS EAST KENTUCKY THROUGH THE REST OF THE NIGHT. THIS
WILL RESULT IN MOSTLY CLEAR SKIES AND GOOD RADIATIONAL COOLING
LIKELY ENCOURAGING THE DEVELOPMENT OF FOG IN THE RIVER VALLEYS.
THE FOG WILL BECOME LOCALLY DENSE TOWARDS DAWN. ACCORDINGLY...
BROUGHT SOME IFR OR LOWER VIS/CIG INTO THE SME AND SJS SITES WITH
MVFR VIS POSSIBLE AT SYM...SIMILAR TO LAST NIGHT. ALL THE FOG
WILL LIFT SHORTLY AFTER 12Z WITH VFR CONDITIONS THROUGH THE REST
OF THE TAF PERIOD FOR MOST SITES. HOWEVER...A COLD FRONT AND
POTENTIAL OUTFLOW BOUNDARIES WILL SPREAD SOUTH INTO NORTHEAST
KENTUCKY LATER THIS AFTERNOON AND EVENING WITH A POSSIBILITY OF
STRONG THUNDERSTORMS...MAINLY NORTH OF INTERSTATE 64. FOR
THIS...HAVE LEFT MENTION OF VCTS IN THE SYM TAF AFTER 21Z. AS FOR
WINDS...EXPECT THEM TO REMAIN LIGHT AND VARIABLE THROUGH MOST OF
THE TAF PERIOD AT ALL THE TAF SITES...HOWEVER LATER THIS
AFTERNOON WE COULD SEE SOME GUSTS OF 10 TO 15 KTS OUT OF THE WSW
AHEAD OF THE FRONT IN THE AS IT DROPS TOWARD THE FAR NORTH.

&&

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

$$

UPDATE...GREIF
SHORT TERM...DJ
LONG TERM...HAL
AVIATION...GREIF



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