FXUS63 KSGF 011741
AFDSGF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SPRINGFIELD MO
1141 AM CST TUE DEC 1 2009

...UPDATE TO AVIATION...

.DISCUSSION...

MAIN FORECAST CONCERNS ARE WITH CLOSED LOW NOW OVER NORTHERN
MEXICO AS IT MOVES NORTHEAST THROUGH THE LOWER AND MID MS VALLY BY
WED EVENING. COLD TEMPERATURES ARE CONCERN IN THE WAKE OF THE
EXITING SYSTEM.

TODAY SHOULD BE THE LAST MILD DAY FOR AWHILE. SFC HIGH EXTENDING
FROM THE WESTERN OH VLY TO THE ARKLATEX REGION COUPLED WITH
TROUGHING OVER THE HIGH PLAINS WILL BRIEFLY PRODUCE A LIGHT SOUTH
WIND. WENT CLOSE TO AVAILABLE MOS TEMPERATURE GUIDANCE/HIGHS IN
THE 50S.

A DEEPENING SFC LOW WILL MOVE FROM THE WESTERN GULF NNE INTO THE
LOWER MS VLY BY 12Z WED IN RESPONSE TO THE APPROACHING UPPER
SYSTEM. MOISTURE ADVECTION SHOULD RAPIDLY INCREASE...BUT WILL TEND
TO FIGHT DRY LOWER LEVELS WITH A CONSTANT FETCH OF DRY AIR
BATTLING LIFT AND MOISTURE OVER THE MO OZARKS. THIS MAY TEND TO
CAUSE PRECIP CHANCES TO HOLD OFF UNTIL AFTER 12Z WED...WITH THE
POSSIBLE EXCEPTION OF AREAS RIGHT ALONG THE MO/AR BORDER. BEST
CHANCES FOR PRECIP WILL BE DURING THE DAY WED AS LIFT IS MAXIMIZED
NORTH OF THE UPPER LOW TRACK WHERE UPPER LEVEL DIFFLUENCE IS
MAXIMIZED IN THE DEFORMATION ZONE AND DEEP ISENTROPIC ASCENT
OCCURS. THERMAL PROFILES THROUGH 18Z WILL SUPPORT RAIN WITH A
TRANSITION TO SNOW FROM NORTHWEST TO SOUTHEAST WED AFTERNOON/EARLY
EVENING. HEAVIER QPF IS EXPECTED OVER SOUTH CENTRAL MO AND POINTS
SOUTH AND EAST WHERE THIS TRANSITION WILL OCCUR LATER IN THE
AFTERNOON. BOTH THE ECMWF AND GFS HAVE TENDED TO SPEED UP THE
UPPER LEVEL LOW PASSAGE...SO IT LOOKS LIKE THERE WILL ONLY BE A
BRIEF PERIOD OF TIME WHEN LIFT AND COLD THERMAL PROFILES (COLD
ENOUGH FOR SNOW) WILL COEXIST. WE COULD SEE A BRIEF ACCUMULATION
WHERE SNOW IS HEAVIER...BUT OTHER FACTORS SUCH AS SFC AIR
TEMPERATURE AND GROUND TEMPERATURE WOULD WORK AGAINST THIS.
SIGNIFICANT PRECIP IS EXPECTED TO END BY WED EVENING.

AN UNSEASONABLY COLD AIR MASS WITH 850MB TEMPERATURES IN THE -10 TO
-14 DEG C RANGE WILL MOVE INTO THE AREA THU/FRI. LIGHT WINDS AND
CLEAR TO PARTLY CLOUDY SKIES MAY ALLOW TEMPS TO BOTTOM OUT WELL
DOWN INTO THE TEENS THU AND FRI NIGHT (MOS GUIDANCE IS IN TEENS
OVER MUCH OF THE CWFA). A MODEST WARMING TREND WILL OCCUR OVER THE
UPCOMING WEEKEND.  DSA

&&

.AVIATION...

WHILE HIGH CLOUDS WILL OVERSPREAD THE REGION THIS AFTERNOON AND
EVENING...VFR CONDITIONS WILL CONTINUE. CLOUDS WILL THICKEN
TONIGHT AS A STORM SYSTEM TRACKS NORTHEAST FROM TEXAS. THIS SYSTEM
WILL TRACK TO THE SOUTH OF AREA WEDNESDAY WHILE A COLD FRONT
PUSHES ACROSS THE REGION. CEILINGS WILL LOWER WEDNESDAY AND
POSSIBLY DROP INTO MVFR CATEGORY BY MIDDAY. AREAS OF LIGHT RAIN
WILL DEVELOP AND PRECIPITATION MAY MIX WITH OR CHANGE TO SNOW FOR A
BRIEF PERIOD BEFORE ENDING LATE WEDNESDAY AFTERNOON. WINDS WILL SHIFT TO
THE NORTHWEST WEDNESDAY MORNING AND GRADUALLY INCREASE THROUGH THE
DAY.

FOSTER

&&

.SGF WATCHES/WARNINGS/ADVISORIES...
MO...NONE.
KS...NONE.
&&

$$