FXUS63 KLMK 262331
AFDLMK

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOUISVILLE KY
631 PM EST SAT DEC 26 2009

...UPDATED AVIATION DISCUSSION...

.SHORT TERM (TONIGHT AND SUNDAY)...

THE UPPER LEVEL LOW SPINNING OVER WISCONSIN WILL MOVE VERY LITTLE 
TONIGHT BEFORE BEGINNING TO TREK EASTWARD TOMORROW AFTERNOON. 
MULTIPLE SPOKES OF ENERGY ROTATING AROUND THIS LOW WILL BRING IN 
SOME REINFORCING COLDER AIR. THIS WILL ALSO BRING A CHANCE FOR SOME 
SNOW TO THE AREA SUNDAY.

FOR TONIGHT...CLOUDS WILL BE ON THE INCREASE OVERNIGHT FROM 
NORTHWEST TO SOUTHEAST WITH MOSTLY CLOUDY SKIES EXPECTED BY TOMORROW 
MORNING AREAWIDE. LIGHT SNOW IS SHOWING UP ON RADAR JUST TO THE 
NORTHWEST OF THE FORECAST AREA IN INDIANA. THOUGH LOW LEVELS OF THE 
ATMOSPHERE HAVE BEEN QUITE DRY IN THIS AREA SOME OF THIS SNOW COULD 
MAKE ITS WAY INTO SOUTHERN INDIANA. THEREFORE HAVE INCLUDED A CHANCE 
FOR FLURRIES IN THIS AREA BEFORE 12Z. ANY FLURRIES SHOULD TAPER OFF 
OVERNIGHT BEFORE LIGHT SNOW WILL AGAIN ENTER THE FORECAST AREA FROM 
THE NORTHWEST TOMORROW AFTERNOON. THE BEST CHANCE FOR SNOW WILL 
BE NORTH OF I-64 WITH LESS THAN AN INCH ACCUMULATION EXPECTED.

TEMPERATURES WILL BE COOLER TONIGHT AND TOMORROW WITH LOWS TONIGHT 
DROPPING INTO THE MID TO UPPER 20S. HIGHS TOMORROW WILL BE IN THE 
LOW TO MID 30S.

.LONG TERM (SUNDAY NIGHT - SATURDAY)...

WILL HAVE ONE MORE LOBE OF ENERGY SWINGING AROUND THE UPPER LOW AS 
IT MAKES PROGRESS ACROSS NORTHERN INDIANA/SOUTHERN MICHIGAN SUNDAY 
NIGHT. MAY HAVE SOME RESIDUAL FLURRIES AS THE VORTMAX CROSSES THE 
REGION...BUT DRYING WILL COME QUICKLY WITH DEEP WEST TO NORTHWEST 
FLOW. HIGH PRESSURE WILL MIGRATE SLOWLY EAST ACROSS THE NORTHERN 
PLAINS STATES MONDAY TO A POSITION OVER THE OHIO RIVER VALLEY 
TUESDAY. MODELS IN GOOD AGREEMENT ON THIS PATTERN...WITH 
NAM/GFS/ECMWF ALL SHOWING RIDGING BUILDING IN ALOFT. 

WEDNESDAY THE HIGH WILL BE TO OUT EAST AND WITH SOUTHWEST FLOW ALOFT 
EXPECT TO SEE INCREASING CIRRUS AHEAD OF NEXT SYSTEM BEGINNING 
TUESDAY NIGHT. THIS SYSTEM WILL BE A BROAD SURFACE TROUGH BETWEEN 
TWO LOW CENTERS...ONE OVER SOUTH CENTRAL CANADA AND ANOTHER OVER THE 
CENTRAL GULF OF MEXICO COAST. BY THURSDAY MORNING...THE SOUTHERN LOW 
WILL BE TRANSITIONING TO THE ATLANTIC. MODELS DIVERGE SOME ON TIMING 
OF THIS TRANSITION AS EACH HAS A SHORTWAVE MOVING WITHIN THE FAST 
SOUTHWEST FLOW AT DIFFERENT TIMES. AS FOR OUR SENSIBLE WEATHER 
DURING THIS PERIOD...MODELS ARE NOT IMPRESSIVE FOR PRECIP AT THIS 
TIME. THE BAND OF MOISTURE ON SOUNDINGS IS NARROW AND 
ELEVATED...THOUGH IT DOES HAVE SOME GOOD LIFT. ANYTHING THAT 
SURVIVES THE SURFACE DRY LAYER WILL BE LIGHT AND AM LEANING MORE 
TOWARDS RAIN DURING THE DAY WEDNESDAY WITH A SWITCH TO EITHER SNOW 
OR LIGHT FREEZING RAIN WEDNESDAY NIGHT. BY THURSDAY MAY SEE ANOTHER 
DAY OF PHASE CHANGES FOR RAIN/SNOW THEN PHASE SHOULD BE ALL ICE 
THURSDAY NIGHT. ENSEMBLES POINT TO WEDNESDAY AFTERNOON/NIGHT FOR 
BEST CHANCE FOR PRECIP AND THESE POPS ARE IN LINE WITH CURRENT 
FORECAST. 

A BROADER TROUGH AXIS WILL MOVE INTO THE OHIO VALLEY AREA 
FRIDAY...WITH THAT AXIS EAST OF THE AREA ON SATURDAY. 00Z ECMWF AND 
TO A LESSER EXTENT THE DGEX AND GFS INDICATE WE MAY GET A SECONDARY 
SHORTWAVE ROTATING AROUND THIS UPPER LOW. WITH THE LOWER THICKNESSES 
ACROSS THE AREA AS WELL AS GOOD COLD AIR ADVECTION...FRIDAY AND 
SATURDAY LOOK TO HAVE TEMPERATURES BELOW NORMAL AFTER A NEAR NORMAL 
MIDWEEK. THE POTENTIAL FOR MULTIPLE SHORTWAVES ROTATING ACROSS THE 
REGION COMBINED WITH SOUNDING PROFILES MOSTLY BELOW FREEZING WILL 
MEAN A SLIGHT CHANCE FOR SNOW FRIDAY AND SATURDAY AS WELL.

&&

.AVIATION (00Z TAF ISSUANCE)...

UPR LO WILL MEANDER ACRS THE UPPER MIDWEST TONIGHT...THEN PIVOT SEWD 
ACRS THE UPR OH VLY SUN. A BAND OF LIGHT SNOW OR FLURRIES WILL 
PRECEDE A VORT LOBE TO THE SOUTH OF THE LOW SUN AFTN AND POSSIBLY 
LOWER FLIGHT CONDITIONS TO MVFR AT KSDF AND KLEX DURING THE AFTN AND 
EARLY EVE. JUST A PERIOD OF FLURRIES EXPECTED AT KBWG. SWLY WINDS 
WILL VEER TO MORE WLY ON SUN AND INCREASE WITH GUSTS TO AROUND 
25KTS.

&&

.LMK WATCHES/WARNINGS/ADVISORIES...
KY...NONE.
IN...NONE.
&&

$$

SHORT TERM........EES
LONG TERM.........RJS
AVIATION..........DK