FXUS63 KLMK 152301
AFDLMK
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOUISVILLE KY
601 PM EST TUE DEC 15 2009
...UPDATED AVIATION DISCUSSION...
.SHORT TERM (TODAY AND TONIGHT)...
UPPER AIR PATTERN SHOWS A FAST PROGRESSIVE ZONAL FLOW ACROSS THE
MID-SECTION OF THE COUNTRY. A BROAD TROUGH NOW ACROSS THE UPPER
MIDWEST WILL TRANSLATE EAST OFF THE MID-ATLANTIC COAST BY WEDNESDAY
AFTERNOON.
THE MAIN STORY IN THE SHORT TERM WILL BE THE ARCTIC AIRMASS
EXPANDING SOUTHEAST INTO THE LOWER OHIO VALLEY. THIS COLD AIR IS
CURRENTLY CENTERED OVER THE MIDWEST AS THE 2 PM SURFACE ANALYSIS
SHOWS THE CENTER OF A SPRAWLING 1035MB SURFACE HIGH RIGHT OVER IOWA.
THIS HIGH PRESSURE CENTER WILL SLIDE SOUTHEAST AND LIE OVER KENTUCKY BY
TOMORROW AFTERNOON. NORTHWEST WINDS WILL BECOME LIGHT NORTHERLY
TOWARDS MORNING AND THEN BECOME LIGHT AND VARIABLE BY TOMORROW
AFTERNOON.
THE BACK EDGE OF WIDESPREAD LOW STRATO-CU NOW IS MOVING SOUTHEAST
ACROSS CENTRAL INDIANA. THIS IS IN GOOD AGREEMENT WITH THE 925MB 90%
RH CONTOUR PROGGED BY THE 12Z NAM. WILL USE THIS MODEL TO BRING
CLEARING TOWARDS THE OHIO RIVER AROUND 4 TO 6 PM...WITH CLEARING
DEVELOPING LATER THIS EVENING ACROSS THE BLUEGRASS AND LAKE
CUMBERLAND REGIONS.
FOR LOW TEMPERATURES TOMORROW MORNING...WILL SIDE WITH THE COOLER
NAM OVER THE MAV GUIDANCE. I WILL EVEN UNDERCUT NAM BY A DEGREE OR
TWO ACROSS OUR FREQUENTLY COOLER LOCATIONS SUCH AS BOWLING GREEN AND
FRANKFORT.
EXPECT A CLASSICALLY SUNNY BUT CRISP WINTER DAY WEDNESDAY. AFTER A
COLD START...LIGHT WINDS AND AMPLE SUN WILL TEMPER THE COLD BY
AFTERNOON AS TEMPERATURES RISE INTO THE UPPER 30S TO THE LOWER 40S.
.LONG TERM (WEDNESDAY - TUESDAY)...
WED NGT THRU FRI...
WE START OFF IN UPR LEVEL NW FLO THIS PERIOD...GO TO ZONAL ON
THU...AND THEN TO SW FRI...AS A SHRTWV TROF DIGS INTO THE LOWER/MID
MS VLY. HI PRES ACRS OUR FA AT THE START OF THE PERIOD WILL SHIFT TO
THE MID ATLANTIC REGION THU EVE...RESULTING IN LIGHT SELY RETURN
FLOW AND A MODEST WARM-UP. AT THAT POINT...LOOKING UPSTREAM...WE SEE
AN INVERTED SFC TROF EXTENDING FROM TEXAS INTO THE MID MS VLY WITH
DEEP MSTR RESIDING PRIMARILY TO THE N AND W OF TROF. AS TROF SHIFTS
TO THE S AND E FRI AND SHRTWV TROF DIGS TO OUR SW...EXPECT
INCREASING CLOUDS (OF THE MID/HI LEVEL VARIETY - PER
CROSS-SECTIONS). SOME OF THOSE CLDS WILL ARRIVE THU NIGHT.
BASED ON THE NEW 12Z EURO...WILL BUMP UP POPS A BIT FOR FRI
NIGHT...THIS MORE IN LINE WITH THE 12Z GFS. PRECIP COULD START AS
RAIN...THEN CHANGE TO SNOW.
FRI NGT THRU TUE...
A LITTLE MORE CONFIDENCE IN THE FCST FOR THIS PERIOD...AT LEAST
EARLY...AS MODELS SHOW SOMEWHAT MORE CONTINUITY. HPC LIKES THE 00Z
CANADIAN/EURO COMBO AT LEAST FOR SAT/SUN. THIS LOOKS TO BE A COLD
PERIOD (TEMPS WELL BELOW NORMAL) WITH SOME LIGHT PRECIPITATION.
BOTH MODELS INDICATE A LNWV TROF APPROACHING AND MOVG THRU OUR FA
SAT NGT FOLLOWED BY A SERIES OF CLIPPER SYSTEMS FOR MON AND TUE.
AT THE SFC...BOTH MODELS INDICATE THE DEVELOPMENT OF AN INVERTED
TROF/WEAK LOW ACRS WKY...MOVG ESE INTO EKY/ETN SAT EVE AND INTO THE
MID ATLANTIC STATES SUN. BASED ON FCST SOUNDINGS AND PLACEMENT OF
DEEP MOISTURE...SAT LOOKS LIKE THE BEST PERIOD FOR SOME MEASURABLE
SNOW...THOUGH WITH TEMPS IN THE MID 30S...THERE WOULD BE SOME
MELTING. AT SOME POINT LATE SAT INTO SAT EVE...TEMPS WOULD LIKELY
FALL ENOUGH FOR SOME MINOR ACCUMS AS WE GET ON THE BACKSIDE OF THE
SYSTEM. THIS COULD END UP BEING AN ADVISORY EVENT...THOUGH IT IS 4
DAYS AWAY AND THERE WILL LIKELY BE CHANGES. THERE WERE SIGNIFICANT
CHANGES IN THE 00Z AND 12Z EURO RUNS WITH THE 00Z RUN SHOWING A
WORST CASE SCENARIO OF PAINTING ABOUT A 1-4 INCH SNOWFALL...WITH
LESSER ACCUMS...ACRS OUR FA SAT/SAT NIGHT.
TEMPS WILL BE COLD ENOUGH OVER THE WEEKEND BUT WILL GET EVEN COLDER
MON AND TUE AS AFOREMENTIONED SYSTEM PASSES AND WE GO TO NW FLOW
WITH SUBSEQUENT CLIPPERS. AT THIS POINT...WILL JUST MENTION FLURRIES
THIS FAR OUT EARLY NEXT WEEK.
&&
.AVIATION (00Z TAF ISSUANCE)...
HIGH PRESSURE CENTERED OVER THE CENTRAL PLAINS WILL GRADUALLY SHIFT
EAST INTO THE OHIO VALLEY. THE ONLY REAL ISSUE FOR THE TAFS TONIGHT
WILL BE THE TIMING OF THE CLEARING WHICH WAS NEAR SDF AND BWG AT
23Z. STILL WITH THE COLD AIR ADVECTION CLEARING WILL BE SLOW AND I
WILL MENTION 01Z AT SDF AND BWG AND 04Z AT LEX. A COLD NORTHWEST
FLOW WILL CONTINUE THROUGH THE TAF FORECAST PERIOD.
&&
.LMK WATCHES/WARNINGS/ADVISORIES...
KY...NONE.
IN...NONE.
&&
$$
SHORT TERM........JSD
LONG TERM.........DK/11
AVIATION..........JA
