Area Forecast Discussion
Issued by NWS Jackson, KY

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000
FXUS63 KJKL 022044
AFDJKL

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JACKSON KY
444 PM EDT SUN AUG 2 2015

.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 18Z TAFS THROUGH 18Z MONDAY AFTERNOON)
ISSUED AT 120 PM EDT SUN AUG 2 2015

HIGH PRESSURE WILL KEEP TAF SITES MOSTLY VFR THROUGH THE TAF
PERIOD. THE EXCEPTION TO THE RULE WILL BE MAINLY RIVER VALLEY FOG
ACROSS THE REGION OVERNIGHT INTO EARLY MONDAY MORNING. WHILE THIS
WILL NOT AFFECT MOST TAF SITES...GIVEN SIMILAR PATTERN HAVE
INTRODUCED LOWER MVFR VIS SME...SJS...AND SYM WHICH HAD THE MOST
AFFECTS FROM FOG THIS MORNING. THERE IS ALSO AN APPROACHING COLD
FRONT AS WE MOVE INTO AFTERNOON HOURS ON MONDAY...BUT STILL
UNCERTAINTY ON HOW QUICKLY WE WILL SEE CONVECTION ACROSS NORTHERN
TAF SITES. THEREFORE WILL HOLD OFF ON ANY MENTION IN THE TAFS AT
THIS TIME GIVEN LOWER CONFIDENCE. WINDS THROUGH THE PERIOD ARE
EXPECTED TO REMAIN LIGHT AND VARIABLE.


&&

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

$$

SHORT TERM...DJ
LONG TERM...HAL
AVIATION...DJ


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