FXUS63 KLMK 120238
AFDLMK
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOUISVILLE KY
938 PM EST FRI DEC 11 2009
...FORECAST UPDATE...
SURFACE HIGH PRESSURE IS CURRENTLY CENTERED OVER EASTERN KY AND WILL
CONTINUE TO MOVE OFF TO THE EAST TONIGHT. CLOUDS OVER TN AND
UPSTREAM IN MO HAVE MADE LITTLE PROGRESS TOWARD THE FORECAST AREA
THIS EVENING THOUGH THEY ARE EXPECTED TO START AFFECTING SOUTHERN
AND WESTERN PORTIONS OF THE AREA BY TOMORROW MORNING. WITH WINDS
GOING CALM IN SOME LOCATIONS HOURLY TEMPS AT THESE SITES ARE RUNNING
A BIT BELOW THE FORECAST. HAVE TWEAKED THE LOW TEMPS DOWN A COUPLE
OF DEGREES FOR A FEW AREAS ACROSS CENTRAL KY AND SOUTHERN IN.
OTHERWISE THE FORECAST IS ON TRACK FOR TONIGHT. UPDATED GRIDS
ALREADY SENT. NO UPDATE TO THE ZONES IS NECESSARY.
.SHORT TERM (TONIGHT AND SATURDAY)...
SURFACE HIGH PRESSURE OVERHEAD HAS ALLOWED FOR SUNNY SKIES THIS
AFTERNOON. A LIGHT WEST-SOUTHWEST WIND HAS ALLOWED AFTERNOON TEMPS
TO CLIMB INTO THE MID AND UPPER 30S. SOME PLACES WILL SEE 40 DEGREES
OR BETTER BEFORE ALL AFTERNOON HEATING WANES.
THE SFC HIGH WILL SLOWLY MOVE EASTWARD OVERNIGHT...ALLOWING FOR GOOD
RADIATIONAL COOLING. SOME HIGH CLOUDS COULD PUSH INTO THE FAR SWRN
CWA AFTER MIDNIGHT...TEMPS WILL STILL DROP INTO THE UPPER TEENS EAST
TO LOW 20S S AND W.
FOR SATURDAY A SYSTEM ACROSS THE GULF WILL MOVE NE TOWARD THE
MID-ATLANTIC COAST. SKIES WILL BECOME MOSTLY CLOUDY SATURDAY
AFTERNOON ACROSS THE SSW FIRST...SPILLING INTO THE NERN CWA BY LATE
AFTERNOON. SOME LIGHT RAIN WILL LIKELY MAKE IT INTO OUR SWRN CWA
BEFORE SUNSET AS THE SREF/GFS ENSEMBLES ARE IN AGREEMENT WITH THIS.
THUS...ACROSS THE SW HAVE INCREASED POPS TO HIGH CHC/LIKELY...WITH
SLIGHT CHC POPS AS FAR NORTH AS A HUNTINGBURG IN TO LIBERTY KY LINE.
PRECIP ONSET WILL BE A COLD RAIN LATE AFTN/BEFORE SUNSET. WILL ALSO
BACK OFF ON TEMPS ACROSS THE SW BECAUSE OF THE CLOUDS/RAIN.
.LONG TERM (SATURDAY NIGHT - FRIDAY)...
SATURDAY NIGHT THROUGH TUESDAY...
DISTINCTLY MILDER AIR WILL ARRIVE BEGINNING SATURDAY...WITH UPPER
50S LIKELY MONDAY.
A SPLIT ZONAL FLOW WILL CROSS THE CONUS SATURDAY INTO MONDAY. ARCTIC
AIR WILL BE CONFINED TO NEW ENGLAND AND ACROSS THE NORTHERN PLAINS
IN THE VICINITY OF THE NORTHERN POLAR JET. EMBEDDED WITHIN THE
SOUTHERN JET ACROSS THE SOUTHERN PLAINS WILL BE A LOW AMPLITUDE WEAK
DISTURBANCE THAT WILL MOVE INTO THE LOWER OHIO VALLEY LATE SUNDAY.
AS STRONG HIGH PRESSURE OF CANADIAN ORIGIN MOVES EASTWARD ACROSS THE
MID ATLANTIC COAST LATE SATURDAY...A STRONG LOW LEVEL JET WILL
DEVELOP LATE SATURDAY. THIS RETURN FLOW WILL BRING MID AND HIGH
LEVEL MOISTURE NORTHWARD. ISENTROPIC LIFT OVER COLDER AIR NEAR THE
SURFACE WILL RESULT IN AN EXPANDING AREA OF RAIN THAT WILL
OVERSPREAD THE LOWER OHIO VALLEY LATE SATURDAY. LIGHT RAIN WILL
LIKELY OVERSPREAD NORTH CENTRAL KENTUCKY AND SOUTHERN OHIO BY LATE
EVENING SATURDAY AND CONTINUE THROUGH EARLY SUNDAY.
IF A COLDER AIRMASS WERE IN PLACE...THIS PRECIPITATION WOULD LIKELY
START AS A MIX OF SLEET OR FREEZING RAIN. HOWEVER...FORECAST
SOUNDINGS AND EVEN ALMOST ALL OF THE SREF ENSEMBLE PTYPES SHOW
PRECIP STARTING AS A COLD RAIN. ACROSS THE NORTHERN BLUEGRASS AND
SOUTHERN INDIANA...A FEW SLEET PELLETS MAY INITIALLY MIX IN WITH THE
RAIN. ANY MIXED PRECIP WILL CHANGE OVER TO RAIN QUICKLY AS WARM AIR
ADVECTION PREDOMINATES. TEMPERATURES SHOULD STAY STEADY OR EVEN RISE
A COUPLE OF DEGREES EARLY SUNDAY MORNING AFTER INITIAL LOWS ARE
ESTABLISHED PROBABLY SATURDAY EVENING.
AS A TROUGH MOVES ACROSS MICHIGAN SUNDAY...MID LEVELS WILL DRY OUT
AND WINDS WILL VEER BEHIND A WEAK COLD FRONT. ALTHOUGH PRECIP WILL
END SUNDAY...WIDESPREAD MOISTURE WITHIN THE BOUNDARY LEVEL WILL
MAINTAIN CLOUDY SKIES FOR MUCH OF THE DAY...WITH PARTIAL CLEARING
LIKELY LATE. THE FRONT EARLY SUNDAY IS OF PACIFIC ORIGIN AND THUS
DON'T EXPECT MUCH IF ANY COOL DOWN SUNDAY. DESPITE CLOUDY
SKIES...EXPECT HIGHS IN THE MID 40S.
THE ECMWF AND THE GFS BOTH SHOW A SECOND DISTURBANCE MOVING TOWARDS
THE GREAT LAKES EARLY TUESDAY. LOW PRESSURE IS FORECAST TO MOVE
TOWARDS LAKE MICHIGAN LATE MONDAY. SOUTHERLY WINDS WILL KEEP
TEMPERATURES QUITE MILD SUNDAY NIGHT THROUGH EARLY TUESDAY. CLOUDS
AND A LACK OF MIXING MAY KEEP TEMPERATURES MONDAY IN THE UPPER
50S...ALTHOUGH WITH SOME SUN...LOWER 60S ARE AT LEAST POSSIBLE.
ARCTIC AIR WILL INVADE THE MIDWEST TUESDAY AS STRONG CONTINENTAL
HIGH PRESSURE IS FORECAST TO SLIDE SOUTH EAST OF THE NORTHERN
ROCKIES. EVENTUALLY THIS HIGH WILL NOSE INTO KENTUCKY BY LATE
THURSDAY. ANY LIGHT PRECIPITATION ASSOCIATED WITH THIS FRONT EARLY
TUESDAY WILL LIKELY MOVE EAST BEFORE THE COLD AIR ARRIVES. EXPECT
CLEARING SKIES AND BRISK WINDS TUESDAY AS MUCH COLDER AIR ARRIVES.
WEDNESDAY AND THURSDAY WILL BE MOSTLY CLEAR WITH SEASONABLY COLD
TEMPERATURES.
&&
.AVIATION (00Z TAF ISSUANCE)...
VFR CONDITIONS WILL CONTINUE THROUGH THIS TAF PERIOD. SURFACE HIGH
PRESSURE IS CENTERED OVER EASTERN KENTUCKY AND WILL CONTINUE TO MOVE
OFF TO THE EAST TOMORROW. CLOUDS WILL SLOWLY BEGIN TO BUILD IN
TOWARDS THE MORNING AS A SYSTEM OVER THE GULF BEGINS TO MOVE
NORTHWARD. RAIN WILL BEGIN TO AFFECT SDF TOMORROW LIKELY AFTER 02Z.
IT WILL BEGIN TO MOVE INTO BWG BEFORE THIS. HOWEVER IT LOOKS TO BE
RIGHT AT THE END OF THE TAF PERIOD. SO WITH UNCERTAINTY IN TIMING
WILL LEAVE IT OUT OF THE TAF FOR THIS ISSUANCE. LIGHT WINDS
OVERNIGHT WILL BEGIN TO BACK BECOMING SSE BY MID MORNING TOMORROW.
&&
.LMK WATCHES/WARNINGS/ADVISORIES...
KY...NONE.
IN...NONE.
&&
$$
UPDATE.........EES
SHORT TERM.....AL
LONG TERM......JSD
AVIATION.......EES
