000
FXUS63 KJKL 301153
AFDJKL

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JACKSON KY
753 AM EDT SAT AUG 30 2008

.SHORT TERM.../TODAY THROUGH MONDAY/

PRIMARY FORECAST ISSUE WILL BE WHETHER OR NOT PRECIPITATION WILL
OCCUR IN VICINITY OF A DIFFUSE AND SLOW MOVING FRONTAL BOUNDARY LATER
TODAY...AS IT MAKES IT WAY SOUTHEAST ACROSS THE FORECAST AREA. THE
VARIOUS MODELS ACTUALLY ARE ALL PRODUCING QPF TO THE NORTHWEST OF
THIS BOUNDARY AS IT SLUGGISHLY DRIFTS INTO TENNESSEE AND VIRGINIA.
THE PROBLEM IS THAT THE MAV AND FWC MOS DATA ARENT REALLY SUPPORTING
PRECIP FOR TODAY. MOST OF THE MODEL TIME HEIGHT CROSS SECTIONS ARE
ONLY SUPPORTING PARTLY CLOUDY SKIES TODAY...WITH LITTLE IF ANY UPWARD
VERTICAL MOTION AND OMEGA. THE NAM12 SEEMS WAY OVERDONE WITH RESPECT
TO QPF AND VERTICAL MOTION...CONSIDERING THE UTTER LACK OF CLOUD
COVER CURRENTLY SHOWING UP IN IR SATELLITE IMAGERY. IN FACT...THE
LATEST RUN OF THE NAM12 MODEL INDICATES THAT IT SHOULD BE RAINING
RIGHT NOW ACROSS EASTERN KENTUCKY...WHICH IT ISNT. WITH ALL THIS IN
MIND...PREFERRED THE GFS MODEL AND MOS DATA. INSPITE OF THE SMALL
AREAS OF QPF THAT ARE SHOWING UP IN THE GFS...THE LACK OF AGREEMENT
BETWEEN THE MAVMOS DATA AND THE GFS TIME HEIGHTS LEAD TO CONTINUANCE
OF A DRY FORECAST FOR THE NEXT FEW DAYS. LATEST NCEP GFS ENSEMBLE MOS
ALSO GOING WITH A DRY FORECAST THROUGH THE LABOR HOLIDAY AS WELL.

TWEAKED TEMPERATURES TO BE A BIT WARMER THAN PREVIOUSLY FORECAST
BOTH TOMORROW AND SUNDAY PER THE WARMER AND MAVMOS...WHICH HAS BEEN
HANDLING DAYTIMES HIGHS THE BEST OVER THE PAST FEW DAYS. MODELS ALSO
INDICATING THAT SOME SOUTHEAST DOWNSLOPE FLOW WILL BE OCCURRING THE
NEXT COUPLE OF AFTERNOONS. THIS IS ANOTHER REASON FOR KEEPING PRECIP
OUT OF THE FORECAST FOR NOW AND FOR INCREASING HIGH TEMPS A BIT.
OVERNIGHT LOWS...DEWPOINTS...AND WINDS WERE ALREADY IN GOOD SHAPE AND
ONLY SLIGHT TWEAKS WERE NEEDED. ALSO FRESHENED UP THE SKY...QPF...AND
WEATHER GRIDS A BIT...BUT NO MAJOR CHANGES WERE MADE.

.LONG TERM.../SUNDAY THROUGH FRIDAY/

A WEAK COLD FRONT WILL BE WASHING OUT TO OUR SOUTH ON SUNDAY. CAN/T
RULE OUT AN ISOLATED STORM OVER THE HIGHER TERRAIN SUNDAY
AFTERNOON...BUT THINK THE PROBABILITY IS ONLY AROUND 10 PERCENT.
OTHERWISE...A STRONG H5 HIGH...AND SURFACE HIGH PRESSURE...WILL BRING
DRY WEATHER AND ABOVE NORMAL TEMPERATURES THROUGH THE END OF THE
PERIOD. MOISTURE FROM GUSTAV SHOULD STAY TO THE SOUTH AND WEST OF THE
AREA AS IT STREAMS NORTH THROUGH THE MISSISSIPPI VALLEY ALONG THE WEST
SIDE OF THE H5 HIGH LATER NEXT WEEK.

&&

.AVIATION.../12Z TO 12Z/...UPDATED

LATE NIGHT AND EARLY MORNING FOG IS LIKELY TO BE THE ONLY CONCERN
DURING THE FORECAST PERIOD. IT WILL BE DENSEST AND MOST PREVALENT IN
VALLEYS...AND LEAST PREVALENT ON RIDGES. THERE IS A REMOTE CHANCE
FOR A FEW SHOWERS OR THUNDERSTORMS ON SATURDAY AFTERNOON...BUT THE
PROBABILITY IS TOO LOW TO ACKNOWLEDGE IN THE FORECAST. IT IS MORE
LIKELY THAT CONVECTIVE CURRENTS WILL BE STIFLED FROM DEEP GROWTH AS
THEY ENCOUNTER DRIER AIR ALOFT AND BEGIN ENTRAINING IT INTO THE MIXED
LAYER AT THE SURFACE.


&&

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

&&

$$

SHORT TERM...AR
LONG TERM....WJM
AVIATION...HAL