FXUS63 KLMK 121106
AFDLMK
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOUISVILLE KY
606 AM EST SAT DEC 12 2009
...UPDATED AVIATION DISCUSSION...
.SHORT TERM (TODAY AND TONIGHT)...
NO MAJOR CHANGES REQUIRED FOR THE SHORT TERM FORECAST. SURFACE HIGH
PRESSURE WILL CONTINUE MOVING EAST OF THE REGION INTO THE MID
ATLANTIC COAST AS A SHORTWAVE IMPULSE MOVES TOWARD THE OHIO VALLEY
TODAY AHEAD OF A WEAK TROUGH. THIS SHORTWAVE WILL BRING INCREASING
MOISTURE FROM THE GULF COAST AND RAIN IS EXPECTED OVERNIGHT. HIGHS
TODAY WILL FEEL RATHER WARM COMPARED TO TEMPERATURES EARLIER THIS
WEEK WITH HIGHS IN THE MID AND UPPER 40S.
THE ONLY REAL NOTICEABLE DIFFERENCE IN TONIGHTS FORECAST WILL BE A
SLOW DOWN IN THE ONSET OF PRECIPITATION. OPERATIONAL
MODELS...ENSEMBLES AND THE 00Z RUN OF THE SPC WRF SHOW THAT PRECIP
WILL LIKELY NOT SPREAD INTO SOUTH CENTRAL KY UNTIL AROUND 00Z AND
CONTINUE MOVING NORTHEASTWARD ACROSS THE AREA INTO NORTH CENTRAL KY
AND SOUTHERN IN BY AROUND 03-06Z. GIVEN THE VERY DRY NATURE OF THE
LOW LEVEL OF THE ATMOSPHERE THIS MAKES SENSE AS IT WILL TAKE SOME
TIME TO MOISTEN THE BOUNDARY LAYER DESPITE INCREASING SOUTHERLY FLOW.
THE OTHER NOTICEABLE CHANGE TO THE FORECAST WAS TO REMOVE MIXED
PRECIP OVERNIGHT. LOOKING AT THERMO PROFILES THE SATURATED BOUNDARY
LAYER WILL REMAIN ABOVE FREEZING THROUGH THE NIGHT AND TEMPERATURES
WILL LIKELY EVEN INCREASE A FEW DEGREES AFTER 06Z AS WARM AIR
ADVECTION PULLS WARMER AIR FROM THE SOUTH INTO THE AREA DURING THIS
OVERRUNNING PRECIPITATION EVENT. OVERNIGHT LOWS WILL FALL INTO THE
MID/UPPER 30S BY AROUND 03Z BEFORE HOLDING STEADY AND MAYBE WARMING
A DEGREE OF TWO BY SUNRISE.
EXPECT PRECIPITATION AMOUNTS TO BE PRETTY LIGHT WITH ANYWHERE FROM A
QUARTER TO HALF INCH AT BEST POSSIBLE AREAWIDE. THIS SYSTEM WILL
MOVE THROUGH FAIRLY QUICKLY WITH PRECIPITATION MOVING EASTWARD AND
DECREASING IN INTENSITY BY SUNRISE SUNDAY MORNING.
.LONG TERM (SUNDAY - FRIDAY)...
SUNDAY THROUGH TUESDAY NIGHT...
UPPER TROUGH IN THE NORTHERN STREAM IS FCST TO SHIFT EASTWARD
THROUGH THE GREAT LAKES REGION ON SUNDAY WITH A SOUTHERN STREAM
SYSTEM PULLING OFF THE EAST COAST DURING THE SAME TIME FRAME.
MOSTLY CLOUDY CONDITIONS WILL START OFF THE DAY ON SUNDAY WITH
SCATTERED PRECIPITATION AROUND. PRECIPITATION IS FORECAST TO END
FROM WEST TO EAST BY AFTERNOON FOLLOWED BY SOME TEMPORARY CLEARING
FOR SUNDAY NIGHT. A GRADIENT OF HIGHS WILL BE NOTED ON SUNDAY WITH
READINGS ONLY WARMING INTO THE LOWER-MID 40S IN THE NORTH AND UPPER
40S ACROSS THE SOUTH. TEMPS ARE NOT EXPECTED TO COOL ALL THAT MUCH
SUNDAY NIGHT WITH LOWS DROPPING INTO MID 30S IN THE NORTH AND UPPER
30S TO LOWER 40S IN THE SOUTH.
ACTIVE WEATHER PATTERN IS FCST TO CONTINUE WITH NEXT MID-LEVEL WAVE
MOVING ACROSS THE PLAINS AND INTO THE OHIO VALLEY LATE MONDAY AND
INTO TUESDAY. SFC CYCLONE IS FCST TO MOVE FROM THE PLAINS INTO THE
GREAT LAKES DURING THE PERIOD WHICH WILL DRAG A DECENT COLD FRONT
THROUGH THE REGION MONDAY NIGHT FOLLOWED BY A PRONOUNCED COOLDOWN
FOR TUESDAY. WARMEST DAY OF THE WEEK LOOKS TO BE ON MONDAY AS STIFF
SOUTHWEST FLOW ALLOWS MILDER AIR TO GET INTO THE REGION. LATEST
MODEL TRENDS ARE NOT AS AGGRESSIVE WITH THE WARMER TEMPS AS PREVIOUS
RUNS. HOWEVER...FEEL THAT HIGHS MONDAY AFTERNOON WILL LIKELY WARM
INTO THE LOWER TO MID 50S IN THE NORTH AND UPPER 50S TO AROUND 60 IN
THE SOUTH. TEMPS ARE LIKELY TO REMAIN QUITE MILD MONDAY NIGHT UNTIL
THE FRONTAL BOUNDARY PASSES THROUGH. WE SHOULD SEE A DECENT FALL IN
TEMPS THROUGHOUT EARLY TUESDAY AND INTO THE AFTERNOON HOURS. HIGHS
TUESDAY WILL LIKELY OCCUR JUST AFTER MIDNIGHT WITH TEMPS FALLING
THEREAFTER. EARLY DAY HIGHS ON TUE WILL BE IN THE UPPER 30S TO THE
LOWER 40S IN THE FAR NW SECTIONS WITH MID TO UPPER 40S ACROSS THE
CENTRAL AND EAST. BUT BY TUESDAY AFTERNOON...MOST LOCATIONS WILL BE
DOWN AROUND FREEZING. VERY COLD TEMPS LOOK LIKELY FOR TUE NIGHT
WITH LOWS DROPPING BACK INTO THE MID-UPPER TEENS ACROSS SOUTHERN
INDIANA AND PORTIONS OF NORTHERN KY...UPPER TEENS TO LOWER 20S WILL
BE FOUND ACROSS SOUTHERN KY.
WEDNESDAY THROUGH FRIDAY...
UPPER AIR PATTERN OVER THE U.S. IS FCST TO TRANSITION INTO A RIDGE
WEST...TROF EAST PATTERN AS WE GO THROUGH THIS FORECAST PERIOD.
BOTH THE 12/00Z GFS AND EURO ARE IN PRETTY GOOD AGREEMENT HERE WITH
A FAIR AMOUNT OF QUIET WEATHER THROUGH THIS PERIOD. SFC HIGH
PRESSURE COMBINED WITH A COLD NW FLOW WILL KEEP THE AREA DRY THROUGH
THE PD WITH BELOW NORMAL TEMPERATURES. BY THU/FRI...BOTH THE EURO
AND GFS ARE PICKING UP A FEW MID-LEVEL WAVES CRUISING THROUGH THE
NORTHERN STREAM WHICH WILL PASS NORTH OF THE REGION. THERE IS SOME
TIMING ISSUES BETWEEN THE MODELS WITH THE GFS BEING A LITTLE FASTER
THAN THE EURO. WITH THE SYSTEMS PASSING NORTH OF THE REGION...WE
WILL KEEP A DRY FORECAST AND THE ONLY CHANGES WILL BE TO TREND TEMPS
CLOSER TO THE RECENT MODEL TRENDS. GIVEN ITS GOOD PERFORMANCE OVER
THE PAST FEW WEEKS...HAVE KEPT TEMPS CLOSE TO THE 2M RAW TEMPS
RATHER THAN THE MOS. HIGHS WED WILL BE IN THE UPPER 20S TO THE
LOWER 30S IN THE NORTH WITH LOWER-MID 30S ACROSS THE SOUTH. AS SFC
HIGH PRESSURE WORKS EAST OF THE REGION FOR THU AND FRIDAY...IT
APPEARS THAT WE'LL GET A LITTLE BIT OF A RETURN FLOW DEVELOPING
WHICH SHOULD ALLOW TEMPS TO WARM IN THE THU/FRI PERIOD. FOR NOW
WILL KEEP TEMPS IN THE MID 30S NORTH...UPPER 30S TO LOWER 40S IN THE
SOUTH ON THU...WITH LOWER TO MID 40S FOR FRIDAY. OVERNIGHT LOWS
WILL BE COLD THROUGH THE PD WITH LOWER TO MID 20S EXPECTED.
&&
.AVIATION (12Z TAF ISSUANCE)...
SURFACE HIGH PRESSURE WILL REMAIN OVER THE MID ATLANTIC COAST TODAY
AND SOUTHERLY FLOW WILL BRING INCREASING CLOUDS AND MOISTURE AHEAD
OF A WEAK DISTURBANCE. VFR CONDITIONS ARE EXPECTED THROUGH MOST OF
THE TAF PERIOD WITH RAIN MOVING INTO BWG AROUND 00Z-03Z AND SDF AND
LEX BETWEEN 03Z-06Z. CIGS WILL DROP TO AROUND 6KFT AT ALL TAF SITE
AROUND 00Z AND MAY FALL TO HIGH MVFR STATUS BY 06Z. VSBYS WILL RANGE
BETWEEN 3 AND 5 SM IN AREAS OF RAIN. RAIN IS EXPECTED TO CONTINUE
THROUGH THE END OF THE TAF PERIOD. SOUTHERLY WINDS UP TO 10 KTS WILL
BEGIN SHIFTING TO THE WEST/SOUTHWEST NEAR THE END OF THE TAF PERIOD.
&&
.LMK WATCHES/WARNINGS/ADVISORIES...
KY...NONE.
IN...NONE.
&&
$$
SHORT TERM........LMS
LONG TERM.........MJ
AVIATION..........LMS
