FXUS63 KLMK 041929
AFDLMK

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOUISVILLE KY
229 PM EST FRI DEC 4 2009

.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 (18Z TAF ISSUANCE)...

MID AND UPPER LEVEL MOISTURE CONTINUE TO STREAM NORTHEAST ACROSS THE 
REGION...WITH KLEX AND KBWG BEING CLOSEST TO THE CLOUD EDGE. WILL 
SEE EXPANSION NORTHWARD THROUGH THE AFTERNOON AND THEN INTO THE 
EVENING. MOISTURE SHOULD BE THICK/COLD ENOUGH TO SUPPORT LIGHT SNOW 
SOUTH AND EAST OF A KLEX TO KBWG LINE AROUND DAYBREAK SATURDAY. TOO 
LOW OF A PROBABILITY AT THIS POINT TO INCLUDE IN EITHER TAF'S 
OUTLOOK PERIOD THOUGH...BUT WOULD NOT BE SURPRISED TO SEE IT 
INTRODUCED WITH NEXT COUPLE OF PACKAGES. 

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..........RJS