FXUS63 KLMK 150444
AFDLMK
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE LOUISVILLE KY
1144 PM EST MON DEC 14 2009
...UPDATED AVIATION DISCUSSION...
.SHORT TERM (TODAY AND TONIGHT)...
SOUTHWEST 500MB FLOW ACROSS THE LOWER OHIO VALLEY WILL TRANSITION TO
A MORE ZONAL FLOW AS A TROUGH MOVES ACROSS THE WESTERN GREAT LAKES
TOMORROW AFTERNOON.
AT THE SURFACE...LOW PRESSURE NOW OVER SOUTHERN MICHIGAN WILL
QUICKLY MOVE EAST ACROSS NEW ENGLAND BY EARLY WEDNESDAY. ARCTIC AIR WILL
INVADE THE LOWER OHIO VALLEY TOMORROW. THIS AIRMASS IS SHALLOW BUT
STILL STRONG...HAVING DROPPED TEMPERATURES AT PONCA CITY OKLAHOMA 27
DEGREES IN THREE HOURS EARLIER THIS MORNING. EARLIER THIS AFTERNOON
AT 2 PM THE FRONT WAS RIGHT OVER ST LOUIS...WITH A 20 DEGREE DROP
JUST BEHIND THE BOUNDARY. THIS FRONT WILL MOVE SOUTHEAST OF THE OHIO
RIVER AROUND MIDNIGHT.
FORECAST SOUNDINGS SHOW SATURATION ONLY UP TO AROUND 4 THOUSAND FEET
OR SO DURING FRONTAL PASSAGE. EXPECT A DRY OVERNIGHT...WITH ONLY SOME
SPRINKLES OR DRIZZLE FOR A COUPLE OF HOURS BEHIND THE FRONT.
THIS EVENING WILL STAY QUITE MILD UNTIL DARK. MOST AREAS WILL STAY
PARTLY CLOUDY UNTIL EARLY EVENING. CLOUDS WILL THICKEN BY MID
EVENING ACROSS SOUTHERN INDIANA AND BECOME CLOUDY BY THE EARLY
MORNING HOURS. WINDS SHOULD SWITCH TO THE WEST AFTER FRONTAL PASSAGE
AND THEN TO THE NORTHWEST BY DAYBREAK.
TEMPERATURES SHOULD STEADILY FALL TOMORROW MORNING...EVEN THROUGH
THE LATE MORNING HOURS AS MODIFIED ARCTIC AIR ARRIVES. WITH CLEARING
EXPECTED DURING THE AFTERNOON...TEMPERATURES MAY RISE A COUPLE OF
DEGREES...BUT WILL STILL STRUGGLE TO EXCEED THE UPPER 30S.
WINDS WILL REMAIN FROM THE NORTHWEST AT 10 TO 15 MPH DURING THE
AFTERNOON...MAKING THE AFTERNOON SEEM BRISK.
.LONG TERM (TUESDAY - SUNDAY)...
TUE NGT THRU THU NGT...
A DRY...COLD PERIOD.
LONGWAVE TROF WILL BE EAST OF OUR FA AT THE START OF THIS PERIOD
WITH NW FLOW DOMINANT AFTERWARD. SKIES WILL HAVE CLEARED BY THEN
WITH COLD HIGH PRESSURE POSITIONED OVER THE MID/UPPER MS VLY. THE
HIGH WILL REACH THE LOWER OHIO VALLEY WED EVE AND THE TN
VLY/NORTHERN GULF STATES THU EVE. SKIES SHUD CONTINUE MAINLY CLR
THRU WED NIGHT WITH A COMBO OF SCANT MOISTURE AND SUBSIDING AIR.
SOME CLDS SHUD MOVE IN FOR THU AND THU NIGHT(OF THE HIGH/MID LEVEL
VARIETY)AS THE NEXT COLD FRONT TAKES SHAPE UPSTREAM OF OUR FA.
OUR CURRENT FCST STRONGLY FAVORS THE NAM MET MOS WITH COLDER TEMPS
THAN GFS MOS THRU MUCH OF THE PERIOD. THIS LOOKS GOOD BASED ON THE
POST FRONTAL AMS UPSTREAM AND TRAJECTORIES.
FRI THRU MON...
THIS IS A LOW CONFIDENCE FCST WITH DIVERGING MODELS/MUCH UNCERTAINTY
...ESPECIALLY FOR SUN AND MON...WHEN WE WILL BASICALLY GO WITH AN
HPC FCST...EXCEPT COLDER TEMPS FOR SUN.
THIS FCST FAVORS PRIMARILY THE CANADIAN MODEL FOR FRI/SAT AND HPC
FOR SUN/MON WITH SUBTLE ADJUSTMENTS AS NOTED ABOVE.
WNW UPR LEVEL FLOW SHUD PREVAIL THRU MUCH OF THE PERIOD WITH TEMPS
TRENDING DOWNWARD TO MUCH BELOW NORMAL BY SUN/MON. WILL KEEP LOW CHC
POPS FOR THE FRI NIGHT THRU SAT NIGHT PERIOD WITH REINFORCING SHOTS
OF COLDER AIR FRI NIGHT AND SAT AS WEAK LOW PRES MOVES PRIMARILY TO
OUR NORTH WITH TRAILING CDFNTS MOVG ACRS OUR FA. PROGGED DEEPEST
MOISTURE APPEARS TO BE ON SAT AS LOW PRES PULLS OFF TO OUR NE WITH
SPOKES/TROFS OF LOW PRES ROTATING ON THE BACKSIDE. AT THAT TIME...
A SHRTWV TROF IS FCST TO AMPLIFY ACRS THE LOWER OH VLY.
BY SUN INTO MON...WILL GO WITH A DRY AND COLD FCST AS CANADIAN HI
PRES DROPS SWD INTO OUR NATIONS MID SECTION AND GRADUALLY SPREADS
EAST.
&&
.AVIATION (06Z TAF ISSUANCE)...
A COLD FRONT WAS LOCATED BETWEEN SDF AND LEX AT 05Z. WINDS HAD
SHIFTED TO THE NORTHWEST AT SDF AND BWG AND WILL SWITCH TO THE
NORTHWEST AT LEX BY 06Z. IT LOOKS AS IF THE IFR CIGS WILL REMAIN
NORTH OF THE TAF SITES OVERNIGHT SO I WILL ONLY MENTION MVFR CIGS.
CIGS SHOULD IMPROVE BY 15Z. NO POST FRONTAL PRECIPITATION IS
EXPECTED.
&&
.LMK WATCHES/WARNINGS/ADVISORIES...
KY...NONE.
IN...NONE.
&&
$$
SHORT TERM........JSD
LONG TERM.........DK/11
AVIATION..........JA
