FXUS63 KLMK 042342
AFDLMK
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOUISVILLE KY
642 PM EST FRI DEC 4 2009
...UPDATED AVIATION DISCUSSION...
.SHORT TERM (TONIGHT AND SATURDAY)...
THE MAIN IMMEDIATE FORECAST CHALLENGE REMAINS THE POSSIBILITY OF
SNOW EARLY SATURDAY MORNING IN THE SOUTHEAST. UPPER TROUGH DIVING IN
FROM THE UPPER MS RIVER VALLEY WILL MERGE WITH SOME MOISTURE
STREAMING UP FROM THE SOUTH TO BRING IN INCREASED MID/UPPER LEVEL
CLOUDS TO THE REGION TONIGHT. MODEL TIME HEIGHT SECTIONS INDICATE
THE LOW LEVELS WILL MOISTEN OVERNIGHT...WITH RH'S LOW ENOUGH TO
SUPPORT SOME SNOW REACHING THE GROUND OVER THE LAKE CUMBERLAND AND
PERHAPS ALSO THE EASTERN PARTS OF THE BLUEGRASS REGION. HAVE SHIFTED
THE SLIGHT CHANCE OF LIGHT SNOW LINE NORTH AND WEST TO INCLUDE
LEXINGTON. STILL NOT EXPECTING ACCUMULATIONS WITH THIS SYSTEM...AS
ROAD WEATHER INFORMATION NETWORKS STILL INDICATE THAT GROUND
TEMPERATURES ARE TOO WARM. GIVEN THAT THIS WOULD BE THE FIRST SNOW
FOR THAT REGION WILL HIGHLIGHT RISK IN HWO AND PUT OUT AN SPS FOR
THE AREA WHERE HAVE HIGHEST SNOW POP...RIGHT ALONG BORDER WITH JKL
FROM CLARK COUNTY SOUTH. THANKS FOR COORDINATION JKL.
AWAY FROM THE SNOW THREAT AREA...STILL LOOKING AT A COLD MORNING
SATURDAY...WITH READINGS SIMILAR TO THIS MORNING. WHEN THE TROUGH
AXIS CLEARS THE REGION LATE SATURDAY MORNING...SKIES WILL CLEAR
QUICKLY. BUT AS WAS THE CASE TODAY...LOW 1000-850 MB THICKNESSES
WILL KEEP READINGS TO THE UPPER 30S AND AROUND 40 ACROSS THE CWA.
.LONG TERM (SATURDAY NIGHT - FRIDAY)...
SATURDAY NIGHT THROUGH MONDAY...
SOUTHWEST FLOW WITH SOME WEAK RIDGING WILL MOVE INTO THE REGION
SATURDAY THROUGH MONDAY. THIS WILL BRING SOMEWHAT WARMER
TEMPERATURES INTO THE AREA WITH HIGHS TOPPING OUT IN THE LOW 40S
NORTH TO UPPER 40S SOUTH UNDER CLEAR SKIES ON SUNDAY WITH INCREASING
CLOUDINESS ON MONDAY. OVERNIGHT LOWS SATURDAY NIGHT WILL STILL BE
QUITE COLD IN THE LOW TO MID 20S GIVEN CLEAR SKIES AND CALM WINDS
BUT BY SUNDAY NIGHT LOWS WILL BE CLOSER TO NORMAL IN THE LOW TO MID
30S.
MOISTURE WILL INCREASE ON THE SOUTHWEST FLOW OVER THE AREA AND A
SHORTWAVE TROUGH WILL PASS THROUGH THE AREA SUNDAY NIGHT INTO MONDAY
AND SOME LIGHT SHOWERS...POSSIBLY MIXING WITH SNOW ACROSS THE
NORTH...WILL BE POSSIBLE LATE SUNDAY NIGHT INTO MONDAY. THIS
DISTURBANCE WILL MOVE QUICKLY EASTWARD MONDAY AFTERNOON AS ANOTHER
SHORTLIVED RIDGE BUILDS OVER THE REGION MONDAY NIGHT INTO TUESDAY.
TUESDAY THROUGH FRIDAY...
ON TUESDAY...SOUTHWEST FLOW WILL INCREASE AND MOISTURE WILL ADVECT
INTO THE REGION AHEAD OF THE NEXT STORM SYSTEM THAT WILL MOVE
EASTWARD OUT OF THE PLAINS. AHEAD OF THIS PLAINS TROUGH...A SLUG OF
GULF MOISTURE WILL RIDE ALONG THE SOUTHWEST FLOW INTO THE OHIO
VALLEY. TEMPERATURES WILL INCREASE UNDER WARM AIR ADVECTION AND
HIGHS WILL REACH INTO THE MID 40S TO NEAR 50. AS THE LOW MOVES
EASTWARD IT WILL STRENGTHEN AND A LOW LEVEL JET AT 850MB WILL
INCREASE TO AROUND 50 KTS BY 00Z WEDNESDAY. SHOWERS WILL BEGIN
MOVING INTO THE REGION BY THIS TIME AHEAD OF A COLD FRONT. THE LOW
WILL TRACK FROM EASTERN KS TO CENTRAL MO/IL BY 06Z WEDNESDAY AND THE
LOW LEVEL JET WILL INCREASE TO 60-70 KTS WITH MODELS SHOWING A
SURFACE LOW AROUND 990 MB. AS THE LOW TRACK INTO NORTHERN IN BY
WEDNESDAY MORNING THE REGION SHOULD EXPERIENCE SOME DRY
SLOTTING...HOWEVER IF THE TRACK OF THE LOW DEVIATES NORTH OR SOUTH
THIS COULD GREATLY AFFECT THE PRECIPITATION FORECAST. AT THIS TIME
TUESDAY NIGHT LOOKS LIKE THE BEST TIME FOR RAIN AND TEMPERATURES
WILL STAY WARM ENOUGH THAT ALL PRECIPITATION SHOULD REMAIN RAINFALL.
IT SHOULD ALSO BE NOTED THAT THIS IS A VERY DYNAMIC SYSTEM AND
DESPITE LIMITED TO NO SURFACE INSTABILITY SHOWERS IN ADDITION TO
STRONG GRADIENT WIND A GOOD DEAL OF LOW LEVEL WIND SHEAR COULD
COMBINE FOR SOME INTERESTING CONDITIONS TUESDAY NIGHT. AT THIS TIME
IT LOOK LIKE WINDY CONDITIONS CAN BE ANTICIPATED REGARDLESS OF ANY
COOL-SEASON SEVERE THREAT THAT MAY DEVELOP. MODEL SOUNDINGS SUGGEST
AT THIS TIME THAT SURFACE GUSTS NEAR 35 KTS ARE POSSIBLE AND GIVEN
THE STRONG LOW LEVEL JET THIS SEEMS REASONABLE AND HAVE INCREASED
WIND SPEEDS TUESDAY NIGHT THROUGH WEDNESDAY.
DURING THE DAY WEDNESDAY THE SURFACE LOW WILL CONTINUE TO TRACK
NORTHEAST ACROSS MI AND INTO SOUTHERN CANADA. AS THE LOW WRAPS
UP...MOISTURE WILL REMAIN OVER THE NORTHERN HALF OF THE FORECAST
AREA AND SOME LIGHT SHOWERS DURING THE DAY COULD TRANSITION TO A
RAIN/SNOW MIX WEDNESDAY NIGHT AS COLD AIR FILTERS INTO THE REGION.
EXPECT LOW TO DROP INTO THE MID AND UPPER 20S WEDNESDAY NIGHT.
THE WARMER TEMPERATURES OF IN THE 40S TO NEAR 50 OF TUESDAY AND
WEDNESDAY WILL BE A MEMORY ON THURSDAY WHEN HIGHS WILL LIGHTLY ONLY
CLIMB INTO THE LOW 30S NORTH TO UPPER 30S SOUTH. FLOW WILL BECOME
ZONAL ON THURSDAY AND TEMPERATURES WILL REMAIN BELOW AVERAGE FOR THE
END OF THE WORK WEEK ON FRIDAY...ALBEIT WARMER THAN THURSDAY WITH
HIGHS IN THE MID 40S.
&&
.AVIATION (00Z TAF ISSUANCE)...
LEX AND BWG WILL BE ON THE WESTERN EDGE OF A WX SYSTEM THAT WILL
PRODUCE SNOW ACRS EKY AND ADJACENT PARTS OF TN AND THE VIRGINIAS.
VFR CONDS SHUD PREVAIL WITH LEX GETTING THE CLOSEST TO MVFR CIGS
TOWARD SAT MORNING.
MID AND UPPER LEVEL MOISTURE CONTINUES TO STREAM NORTHEAST ACROSS
THE REGION. MOISTURE SHOULD BE SUFFICIENTLY DEEP AND TEMPS COLD
ENOUGH TO SUPPORT LIGHT SNOW SOUTH AND EAST OF A LEX TO BWG LINE IN
THE PREDAWN SAT. SOME FLURRIES COULD REACH LEX AND BWG...MOST LIKELY
AT LEX.
BY LATE MORNING...UPPER TROUGH AXIS WILL SWING BY REGION AND TAKE
CLOUDS WITH IT.
&&
.LMK WATCHES/WARNINGS/ADVISORIES...
KY...NONE.
IN...NONE.
&&
$$
SHORT TERM........RJS
LONG TERM.........LMS
AVIATION..........DK/11
