000
FXUS63 KJKL 210725
AFDJKL

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JACKSON KY
325 AM EDT TUE MAY 21 2013

.SHORT TERM...(TODAY THROUGH WEDNESDAY)
ISSUED AT 324 AM EDT TUE MAY 21 2013

A CLOSED UPPER LEVEL LOW WAS CENTERED OVER THE DAKOTAS EARLY THIS
MORNING WITH A SHORTWAVE TROUGH WORKING TOWARD THE MS VALLEY REGION
AND ANOTHER SHORTWAVE WORKING FROM THE SOUTHERN ROCKIES TOWARD THE
SOUTHERN PLAINS. AT THE SFC...AN AREA OF LOW PRESSURE WAS LOCATED
NEAR THE SD/MN BORDER WITH A WARM FRONT EXTENDING EAST ACROSS THE
GREAT LAKES INTO NEW ENGLAND AND A COLD FRONT TRAILING SOUTH AND THEN
SOUTHWEST INTO THE SOUTHERN PLAINS. PREFRONTAL CONVECTION HAS
WEAKENED BUT EXTENDS FROM THE WESTERN GREAT LAKES INTO HE LOWER OH
VALLEY REGION...NORTH OF THE OWB AND PAH AREA AND THEN CONTINUES
SOUTH GENERALLY ALONG THE MS RIVER AND THEN WEST INTO EAST CENTRAL
AR. IT DOES APPEAR THAT THIS CONVECTION HAS OUTFLOWED WITH AN OUTFLOW
BOUNDARY FROM CENTRAL IN DOWN TO NEAR THE EVV VICINITY. LOCALLY
ACROSS EASTERN KY 11-3.9 IMAGERY INDICATES A BIT OF LOW CLOUDS NEAR
BLACK MOUNTAIN AND IN SW VA AND VALLEY FOG...ESPECIALLY IN THE BIG
SANDY REGION. SOME DEBRIS CIRRUS SI ALSO PASSING OVERHEAD.


EARLY THIS MORNING...VALLEY FOG WILL LIKELY CONTINUE AND BECOME DENSE
IN SOME AREAS BEFORE DAWN...DESPITE SOME PASSING CIRRUS. COVERAGE OF
THIS SHOULD BE A BIT MORE WIDESPREAD OVER THE SOUTHEAST THAT
EXPERIENCED CONVECTION OVER THE PAST 24 HORUS. A PREFIRST PERIOD
WILL BE USED TO COVER THIS.

THE 4Z HRRR AND 0Z NAM GENERALLY SEEM TO BRING AN OUTFLOW BOUNDARY
FROM CONVECTION TO OUR NORTH AND WEST ACROSS THE COMMONWEALTH THIS
MORNING AND INTO EASTERN KY IN THE AFTERNOON. ANY CONVECTION ALONG
WITH WILL PROBABLY BE ISOLATED TO SCATTERED IN NATURE. THE 0Z NAM AND
0Z GFS DIFFER CONSIDERABLY ON INSTABILITY FROM MIDDAY INTO THE
AFTERNOON. THE 0Z NAM FORECASTS A CONSIDERABLE AMOUNT OF MIDLEVEL DRY
AIR AND STEEPER LAPSE RATES ALOFT AS COMPARED TO THE 0Z GFS WHILE THE
GFS IS MORE TAME. THE 0Z NAM LIKELY MOISTENS UP THE BOUNDARY LAYER A
TAD TOO MUCH LEADING TO DEWPOINTS NEARING 70 AND RESULTING IN TOTAL
TOTALS OVER 50...CAPE OVER 50 AND LI OF -9C OR LOWER. REALITY WOULD
PROBABLY BE SOMEWHERE IN BETWEEN...MORE ON THE ORDER OF CAPE IN THE
2000 TO 3000 J/KG RANGE AND LI -4C TO -6C OR SO AND 21Z SREF HAS HIGH
PROBABILITIES OF CAPE GREATER THAN 2000 J/KG AND LI LESS THAN -4C.
THIS WOULD STILL BE SUPPORTIVE OF SOME STRONGER STORMS AND POSSIBLY A
LOCALLY SEVERE STORM WITH HEAVY RAIN...ESPECIALLY IF THERE WERE TO BE
ANY CELL MERGERS. A ONE OR TWO HOUR DIFFERENCE IN CU DEVELOPMENT AND
CONVECTIVE DEVELOPMENT WILL DETERMINE MAX T TODAY. HOWEVER...IT STILL
APPEARS THAT MAX T WILL BE CLOSE TO BREAKING THE RECORD FOR TODAY AT
JKL AND POSSIBLY COME CLOSE AT LOZ.

LOSS OF DAYTIME HEATING WILL LEAD TO LESS ACTIVITY AFTER 0Z AS THE
STRENGTHENING LOW LEVEL JET AND APPROACHING COLD FRONT/MID LEVEL
SHORTWAVE SHOULD FOCUS CONVECTION TO OUR WEST AND NORTHWEST FOR MUCH
OF TONIGHT. IF CLEARING TAKES PLACE...VALLEY FOG SHOULD DEVELOP AND
POSSIBLY BECOME DENSE...ESPECIALLY WHERE ANY CONVECTION OCCURS LATER
TODAY. ATTM...WE PLAN NOT MENTION DENSE FOG JUST PATCHY FOG TO AREAS
OF FOG.

ON WEDNESDAY...THE COLD FRONT AND MID LEVEL WAVE WILL APPROACH THE
AREA...THOUGH THE LOW LEVEL JET CORE WITH THE STRONGER WINDS ALOFT
GENERALLY TO OUR NORTH AND NORTHWEST. SOME DEGREE OF DEBRIS CLOUDS
MAY WORK ACROSS THE AREA ON WED...BUT MODERATE 0Z MODELS AND 21Z
FORECAST MODERATE INSTABILITY AND MORE IN THE WAY OF SHEAR AS
COMPARED TO TODAY. THIS SHOULD LEAD TO STRENGTHENING OF CONVECTION AS
IT MOVES INTO EASTERN KY AND PROBABLY AN UPTICK IN COVERAGE AS WELL.
ONE OR MORE LINES OF STORMS...POSSIBLY STRONG TO LOCALLY SEVERE
SHOULD WORK ACROSS THE REGION. GUSTY WINDS WOULD APPEAR TO BE THE
PRIMARY THREAT WITH STORMS ON WED...THOUGH SOME SMALL TO MARGINALLY
SEVERE HAIL COULD OCCUR AS WELL AS LOCALLY HEAVY RAIN. LIKELY POPS
WERE CONTINUED FOR WEDNESDAY. ONCE AGAIN TIMING OF ARRIVAL OF DEBRIS
CLOUDS AND CONVECTIVE DEVELOPMENT WILL DETERMINE MAX T ON WED...BUT
EASTERN LOCATIONS SHOULD SEE THIS OCCUR THE LATEST AND SHOULD AVERAGE
WARMER THAN MORE CENTRAL AND WESTERN LOCATIONS.

.LONG TERM...(WEDNESDAY NIGHT THROUGH MONDAY)
ISSUED AT 325 AM EDT TUE MAY 21 2013

THE EXTENDED FORECAST DISCUSSION WILL BE ISSUED SHORTLY.

&&

.AVIATION...(FOR THE 06Z TAFS THROUGH 06Z TUESDAY NIGHT)
ISSUED AT 205 AM EDT TUE MAY 21 2013

MOSTLY CLEAR SKIES AND DEWPOINTS IN THE 60S HAVE ALREADY LED TO FOG
DEVELOPMENT IN THE VALLEYS AND PER OBS THIS MAY BE DENSE IS SOME
LOCATIONS IN THE BIG SANDY/TUG VALLEY REGION ATTM. KI35...K22 AND
KPBX SHOULD EXPERIENCE SOME OF THE LOWER VIS THROUGH 13Z.
HOWEVER...GUIDANCE ONLY TAKES LOZ AND SME DOWN TO MVFR AROUND 9Z.
EXPECT SHOWERS AND THUNDERSTORMS TO DEVELOP 16Z AND AFTER...POSSIBLY
SOONER AS SOME MODEL GUIDANCE BRINGS AND OUTFLOW BOUNDARY INTO THE
AREA BEFORE 16Z. WE HAVE CONTINUED WITH SOME VCTS AND CB FOR THIS IN
THE TAFS. WINDS THROUGH THE NIGHT WILL BE LIGHT AND VARIABLE...PICKING
UP FROM THE SOUTHWEST WITH SPEEDS UP TO 10 KTS POSSIBLE AFTER 13Z.


&&

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

$$

SHORT TERM...JP
LONG TERM...GEOGERIAN
AVIATION...JP