000
FXUS63 KLMK 280247
AFDLMK
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOUISVILLE KY
947 PM EST MON DEC 27 2010
...FORECAST UPDATE...
LOW LEVEL CLOUDS CONTINUE TO ERODE ACROSS SRN IN FROM S TO N...AND
ACROSS THE BLUEGRASS REGION FROM W TO E. WITH HIGH PRESSURE NOSING
INTO THE REGION...CLEARING SKIES...LIGHT WINDS AND A SNOW PACK IN
PLACES...TEMPERATURES MAY BOTTOM OUT TONIGHT UNDER GOOD RADIATIONAL
COOLING. HOWEVER...CURRENT DEWPOINTS ARE IN THE MID TEENS OR HIGHER
SO WOULD NOT EXPECT OVERNIGHT LOWS TO DROP MUCH BELOW THAT IN
PLACES. ESPECIALLY OVER OUR NWRN CWA WHERE WINDS HAVE CHANGED TO A
SRLY/SWRLY DIRECTION...OR OUR FAR ERN BLUEGRASS COUNTIES WHERE
CLOUDS ARE SLOW TO ERODE.
WITH CLEAR SKIES...SNOW PACK AND COLDEST DEWPOINTS SE...THINK THE
LAKE CUMBERLAND AREA WILL SEE THE COLDEST TEMPS TONIGHT IN THE MID
TO PERHAPS LOW TEENS. ELSEWHERE TEMPS WILL BE IN THE UPPER TEENS TO
VERY LOW 20S IN THE WARMEST SPOTS. ADJUSTED TEMPS SLIGHTLY...BUT DID
MAKE SIGNIFICANT CHANGES TO CLOUD GRIDS. NOT ENOUGH OVERALL CHANGE
FOR A ZONE UPDATE BUT WILL SEND UPDATES TO THE WEB SHORTLY.
.SHORT TERM (TONIGHT AND TUESDAY)...
LOW-LEVEL CLOUDS CONTINUE TO HANG AROUND THE REGION AS THE RIDGE
AXIS HAS NOT MADE IT TO OUR AREA JUST YET. THIS HAS HELD TEMPS DOWN
A BIT. HOWEVER...THERE HAVE BEEN A FEW BREAKS IN THE CLOUD
COVER...WHICH HAS ALLOWED TEMPS TO RISE INTO THE LOWER 30S...MAINLY
ACROSS OUR WEST AND SOUTHWEST FORECAST AREA. TAKING A LOOK AT
WEBCAMS ACROSS THE AREA THIS AFTERNOON ILLUSTRATED THAT THE SNOWPACK
IS SLOWLY DIMINISHING...PARTICULARLY IN THE AREAS THAT WITNESSED
SOME CLEARING. ANTICIPATE SKIES TO CONTINUE CLEARING FROM WEST TO
EAST THROUGH THE OVERNIGHT HOURS AS HIGH PRESSURE CONTINUES TO MOVE
EASTWARD. BY TOMORROW MORNING...SURFACE HIGH PRESSURE WILL BE
ESTABLISHED ACROSS CENTRAL TENNESSEE.
AS FOR TEMPERATURES...OVERNIGHT LOWS ARE EXPECTED TO GET RATHER
COLD. WITH CLEARING SKIES...LIGHT WINDS...AND SOME AREAS WITH A
REMAINING SNOWPACK...EXPECT RADIATIONAL COOLING TO DROP TEMPERATURES
INTO THE MID AND UPPER TEENS CWA-WIDE. WINDS WILL BE LIGHT...BUT THE
WIND CHILL VALUES COULD STILL DIP INTO THE SINGLE DIGITS BY SUNRISE.
OF COURSE...THESE FORECAST TEMPERATURES ARE BASED ON THE DIMINISHING
CLOUD COVER OVERNIGHT. IF CLOUDS HANG AROUND A LITTLE LONGER THAN
ANTICIPATED...TEMPS COULD REMAIN SLIGHTLY WARMER THAN FORECAST.
SOUTHWESTERLY WINDS WILL INCREASE AS WE GET INTO THE RETURN FLOW
PATTERN AND SKIES SHOULD BE MOSTLY SUNNY TOMORROW WITH HIGH PRESSURE
PARKED JUST TO OUR SOUTH AND EAST. THIS SHOULD ALLOW HIGH
TEMPERATURES TO REACH THE LOW TO MID 30S ACROSS MOST OF THE FORECAST
AREA WITH UPPER 30S ACROSS OUR EXTREME SOUTH/SOUTHWEST COUNTIES.
.LONG TERM (TUESDAY NIGHT - MONDAY)...
MODELS STILL INDICATING THE HIGH PRESSURE MOVING ACROSS THE LOWER MS
RIVER VALLEY WILL STALL OVER THE TENNESSEE VALLEY AT THE START OF
THE PERIOD...THEN GET NUDGED EAST WEDNESDAY AS LOW PRESSURE GETS
ORGANIZED JUST EAST OF THE CENTRAL ROCKIES. THE DELAY CONTINUES TO
LESSEN OUR THREAT FOR LIGHT RAIN WEDNESDAY AFTERNOON. WEDNESDAY
NIGHT STILL LOOKS GOOD FOR RAIN AS A SHORTWAVE TROUGH MOVES ACROSS
THE MID MISSISSIPPI RIVER VALLEY AND INITIATES GOOD LIFT ALONG A
WARM FRONT FORECAST TO MOVE THROUGH THE REGION. STILL LOOKS VERY
MARGINAL ACROSS OUR NORTHEAST CWA FOR SOME OF THIS PRECIP TO FALL AS
A LIGHT FREEZING RAIN...BUT WITH DEEP WARM AIR PUNCHING IN QUICKLY
AND AN ERODING SNOWPACK...IT IS ONLY 1-3 INCHES NOW AND SHOULD MELT
SOME DURING THE DAY TUESDAY AND WEDNESDAY...WILL KEEP OUT OF THE
FORECAST AT THIS TIME.
THE LOW WILL PUSH INTO THE CENTRAL PLAINS THURSDAY. THE PRESSURE
GRADIENT BETWEEN IT AND THE SLOW MOVING HIGH TO OUR EAST WILL BRING
STRONG WARM AIR ADVECTION ACROSS THE REGION...BRINGING TEMPS UP TO
THE MID TO UPPER 40S AS WELL AS INCREASING OUR MOISTURE AND BRINGING
GUSTY SOUTH WINDS. GIVEN THE WELL ABOVE NORMAL PRECIPITABLE WATER
ACROSS THE AREA CANNOT RULE OUT A FEW LOW-TOPPED SHOWERS
DEVELOPING...SO WILL KEEP IN CHANCE POPS FOR NOW. THE PATTERN DOES
NOT CHANGE MUCH FOR FRIDAY. THE ONLY SENSIBLE CHANGE WILL BE IN THE
CONTINUED WARMUP...WITH HIGHS INTO THE MID TO UPPER 50S.
TIMING FOR THE FRONTAL PASSAGE STILL ON TRACK FOR FRIDAY NIGHT
SATURDAY MORNING...AS THE LOW KICKS NORTH INTO SOUTH CENTRAL
ONTARIO. WINDS ALOFT WILL BE CRANKING...AS GFS HAS COME BACK UP FOR
ITS 850 JET EARLY SATURDAY...BACK TO 70-80 KNOTS. STILL WITH
INSTABILITY WELL ELEVATED...JUST EXPECTING THUNDERSTORMS WITH FAST
MOVING LOW CLOUDS HERE. THE BETTER SURFACE INSTABILITY LOOKS TO BE
OVER SOUTHERN TN AND POINTS FARTHER SOUTH. MODEL PW'S CONTINUE TO
ADVERTISE NUMBERS IN THE 1.3" RANGE JUST AHEAD OF THE FRONT. WILL
CONTINUE TO BUMP UP POPS AND QPF. THE RAIN WILL FALL INTO RIVER
BASINS THAT SHOULD BE ABLE TO HANDLE IT WELL...SO NO FLOOD CONCERNS
AT THIS POINT.
FOR SATURDAY AFTERNOON THROUGH SUNDAY...THE 00Z AND NOW THE 12Z
MODELS HAVE BACKED OFF ON HANGING THE FRONT UP OVER THE AREA.
INSTEAD THEY HAVE HIGH PRESSURE PUSHING IN FROM THE WEST AND DRYING
US OUT QUICKLY. TO AVOID FLIP FLOPPING AS MUCH...WILL TREND POPS
DOWN BUT NOT DRY US OUT COMPLETELY. GIVEN THE COLD AIR FILTERING IN
WILL HAVE TO HAVE A CHANGEOVER TO SNOW IN FOR THESE PERIODS...BUT
WILL KEEP ACCUMULATIONS LIGHT. MONDAY SHOULD BE DRY WITH THAT HIGH
OVER THE AREA AND A SLOW WARMUP IN STORE.
&&
.AVIATION (00Z TAF ISSUANCE)...
SFC HIGH PRESSURE WILL SLIDE FROM WEST TO EAST ACROSS THE TN VALLEY
TONIGHT AND INTO TUESDAY...HELPING TO SCATTER OUT OUR MVFR-LOW VFR
CIGS TONIGHT. BWG HAS ALREADY CLEARED...WHERE LEX WILL BE UNDER THE
CANOPY OF CLOUDS THE LONGEST...PERHAPS UNTIL CLOSER TO 06Z TONIGHT.
BECAUSE OF CLEARING SKIES TONIGHT THOUGH...BWG OR LEX VSBYS MAY DROP
TO MVFR DUE TO BR WITH ADDED MOISTURE IN THE LOW-LEVELS FROM THE
SNOWPACK. ONCE STRATUS/STRATO-CU DISSIPATES...ONLY A FEW HIGH CIRRUS
WILL BE EXPECTED AFTER 12Z TUES...WITH MOSTLY SUNNY SKIES IN PLACE.
WITH THE HIGH PRESSURE SLIDING EAST...A WESTERLY-NORTHWESTERLY WIND
WILL GENERALLY BE LIGHT TO CALM OVERNIGHT...WITH SOUTHWEST WINDS
ENSUING TOMORROW FROM ROUGHLY 5-8-KTS WITH HIGHER GUSTS IN THE TEENS
POSSIBLE.
&&
.LMK WATCHES/WARNINGS/ADVISORIES...
KY...NONE.
IN...NONE.
&&
$$
UPDATE.........AL
SHORT TERM.....MJP
LONG TERM......RJS
AVIATION.......AL
