FXUS63 KJKL 040551
AFDJKL
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE JACKSON KY
1251 AM EST FRI DEC 4 2009
.SHORT TERM.../THE REST OF TONIGHT/
INGESTED HOURLY OBSERVED TEMPERATURE...DEWPOINT...AND WIND DATA INTO
THE GRIDS TO ESTABLISH NEW TRENDS IN THE FORECAST GRIDS. ALSO REMOVED
EVENING WORDING FROM THE TONIGHT PERIOD OF THE ZONE TEXT PRODUCT.
BASED ON OBSERVED TRENDS IN HOURLY TEMPERATURES SINCE THE START OF
THE SHIFT...FOUND IT NECESSARY TO INCREASE BOTH HOURLY AND OVERNIGHT
MINIMUM TEMPERATURES BY SEVERAL DEGREES. TONIGHTS LOW TEMPERATURES
OVERALL WILL BE IN THE LOW TO MID 30S ACROSS THE BOARD....AS OPPOSED
TO THE MID TO UPPER 20S THAT WERE PREVIOUSLY FORECAST. HAVE DRIZZLE
ENDING BETWEEN 4 AND 5Z TONIGHT. WITH SUBFREEZING TEMPERATURES
ONGOING AT AFD ISSUANCE IN THE HIGHER ELEVATIONS ALONG THE VIRGINIA
BORDER...ALSO HAD TO ADD POTENTIAL FOR FREEZING DRIZZLE ABOVE 2000
FEET BASED ON LATEST FORECAST SOUNDINGS TO BOTH THE FORECAST GRIDS
AND UPDATED ZONE TEXT PRODUCT. INCREASED OVERALL CLOUD COVER
OVERNIGHT AS THE LATEST MODEL DATA AND SATELLITE DATA INDICATE THE
CLOUDS WILL BE VERY SLOW TO MOVE AWAY OR DISSIPATE UNTIL AROUND
SUNRISE TOMORROW. THE REST OF THE FORECAST WAS IN GOOD SHAPE.
THE PREVIOUS SHORT TERM FORECAST DISCUSSION FOLLOWS...
/TONIGHT THROUGH SATURDAY/
CURRENT 50H LOW SPINNING THRU NRN ME WITH COLD AIR ADVECTION SWEEPING
INTO THE OH RIVER VALLEY. TEMPS TODAY HAVE BEEN SLOWLY SLIPPING FROM
SUNRISE VALUES IN THE LOWER 40S TO CURRENT NUMBERS IN THE UPPER 30S.
LOW SUN ANGLE UNABLE TO PENETRATE THE DENSE LOW CLOUDS THAT HAVE BEEN
PUSHED UP AGAINST THE MTNS. -RA/-DZ AND CEILINGS BETWEEN 600 AND
1500 FEET HAVE BEEN THE NORM. HAVE BEEN WATCHING THE BACK EDGE OF THE
SC AND IT HASN'T EVEN MADE IT TO CENTRAL KY. BEHIND THIS IS A LARGE
AREA OF COLD CU THAT SHOWS NO SIGN OF DIMINISHING. EXPECT THE CLOUDS
TO CONTINUE OVERNIGHT WHICH SHOULD HELP KEEP THE TEMP FROM DROPPING
THRU THE FLOOR. SOME CLEARING ON FRI WHICH WILL HELP THE TEMP TO
RECOVER TO NEAR WEDNESDAY MORNING HIGHS.
NEXT 50H VORT SHOWING UP ON WV SAT OVER SOUTHWESTERN MN. THIS IS REFLECTED AT
THE SFC BY A TROF BUT NO CLOSED LOW. EXPECT THE 50H LOW TO DROP INTO
THE SRN MS RIVER VALLEY AND LINK WITH A SFC WAVE THAT FORMS IN THE WESTERN
GULF. THIS COMBINATION WILL TRACK UP THE ATLANTIC COAST AND BRING
GOOD RAINFALL TO THE ATLANTIC STATES. APPALACHIAN MTNS SHOULD BLOCK
MOST MOISTURE RETURN INTO ERN KY. LACK OF RETURN MOISTURE COMBINED
WITH LACK OF ADVECTED GULF MOISTURE WILL LIMIT CHANCES OF PCPN IN ERN
KY. COLD AIR WILL REMAIN AND WITH THE BRUSH WITH THE ATLANTIC LOW...
WE SHOULD SEE SOME CONTINUED UPSLOPE PCPN. EXPECT THE BEST PCPN TO BE
IN THE FORM OF SNOW AND MAINLY DURING THE DAY ON SAT. ATLANTIC SYSTEM
TRACKS RAPIDLY TO NEW ENG AND PULLS ANY REMAINING PCPN WITH IT
RESULTING IN CLEARING LATE SAT. HAVE GENERALLY FOLLOWED THE GFS MODEL
FOR TEMPS AS THE NAM SEEMED TOO COLD BUT HAVE GIVEN IT SOME DUE AND
UNDERCUT THE GFS TEMPS BY A DEG OR TWO.
.LONG TERM.../SATURDAY NIGHT THROUGH THURSDAY/
PROGRESSIVE PATTERN WILL CONTINUE THROUGH THE LONG TERM PERIOD WITH
TWO SYSTEMS TO DEAL WITH. OVERALL... PROGS REMAIN IN RELATIVELY GOOD
AGREEMENT SO CONFIDENCE CONTINUES TO BUILD... ESPECIALLY REGARDING A
RATHER HEALTHY SYSTEM LIKELY TO AFFECT THE EASTERN U.S. DURING THE
MIDDLE OF NEXT WEEK. WHILE THERE WILL NO DOUBT BE CHILLY SPELLS...
THERE SEEMS TO BE NO MAJOR ARCTIC OUTBREAK ON THE HORIZON FOR OUR
AREA AS FAST ZONAL FLOW PATTERN FLOODS THE CONUS WITH PACIFIC AIR
WHILE KEEPING THE ARCTIC AIR MASS LOCKED WELL TO OUR NORTH.
THE COLDEST NIGHT OF THE PERIOD... AND PROBABLY ONE OF THE COLDEST
NIGHTS SO FAR THIS FALL/WINTER LOOKS TO BE SATURDAY NIGHT AS OUR
SATURDAY SYSTEM MOVES OFF QUICKLY TO THE EAST LEAVING CLEARING
SKIES. TEMPS SHOULD THUS TUMBLE INTO THE LOWER 20S WITH A FEW UPPER
TEENS PROBABLE... ESPECIALLY IF THERE IS ANY SNOW ON THE GROUND IN
OUR FAR SOUTHEASTERN COUNTIES. OTHERWISE... HIGH PRESSURE WILL
DOMINATE THROUGH SUNDAY NIGHT WITH A VERY DRY AIR MASS IN PLACE.
THIS DRY AIR MASS WILL BE A HINDRANCE TO A WEAK FRONTAL BOUNDARY
WHICH IS PROGGED TO PASS THROUGH THE AREA ON MONDAY AND WE WILL ONLY
OFFER A SLIGHT CHANCE OF A SHOWER WITH THIS SYSTEM. WILL HAVE TO
WATCH THE TIMING OF THE SYSTEM THOUGH AS IT COULD BRING A BIT OF
FREEZING RAIN EARLY MONDAY MORNING IF THE FRONT IS A FEW HOURS
QUICKER AND ANY PRECIP ACTUALLY FALLS FROM IT.
WEAK HIGH PRESSURE WILL BUILD INTO THE REGION LATE MONDAY NIGHT INTO
EARLY TUESDAY... BUT THE NEXT STORM SYSTEM ORGANIZING TO OUR
SOUTHWEST WILL THEN BRING INCREASING RAIN CHANCES LATE ON TUESDAY
INTO WEDNESDAY. WHILE CONFIDENCE IS INCREASING WITH THIS SYSTEM...
THERE WILL NO DOUBT BE SOME CHANGES WITH THE TIMING AS THE EVENT
NEARS SO ONLY INCREASED POPS TO AROUND 50 PERCENT TUESDAY NIGHT AND
WEDNESDAY FOR NOW. COLDER AIR WILL THEN WRAP AROUND THE SYSTEM
WEDNESDAY NIGHT SO A CHANGEOVER TO A FEW SNOW SHOWERS IS POSSIBLE
BEFORE THE PRECIP ENDS. DRIER AND COOLER THEN FOR THURSDAY.
&&
.AVIATION.../06Z TO 06Z/...UPDATED
CEILINGS WERE MVFR AT TAF ISSUANCE TIME...WITH LOW CEILINGS FROM THE
OHIO INDIANA BORDER TO JUST WEST OF LEXINGTON. THIS LINE SHOULD
CONTINUE MOVING TO THE EAST. HAVE THE CIGS GOING TO VFR NEAR DAWN AS
THIS LINE MOVES EAST. DUE TO THE HIGHER TERRAIN IN EASTERN
KENTUCKY...THERE WILL STILL BE SOME POCKETS OF MVFR TROUGH THE MID
MORNING...BUT MAINLY TO TO THE EAST NEAR THE WV AND VA BORDERS.
CONDITIONS WILL REMAIN VFR THROUGH 06Z...HOWEVER WILL TUMBLE BACK TO
IFR EARLY ON SATURDAY AS THE UPPER TROUGH MOVES THROUGH THE AREA
BRINGING A SPURT OF SNOW SHOWERS ACROSS THE AREA.
&&
.JKL WATCHES/WARNINGS/ADVISORIES...NONE.
&&
$$
SHORT TERM...DUSTY/AR
LONG TERM....ABE
AVIATION...JJ
