FXUS63 KSGF 021137
AFDSGF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SPRINGFIELD MO
537 AM CST WED DEC 2 2009

...UPDATE TO AVIATION...

.DISCUSSION...

THE MAIN FORECAST CONCERNS REMAIN PRECIPITATION AREAL
EXTENT...AMOUNTS...AND TO SOME EXTENT PRECIP TYPE WITH THE STRONG
UPPER LEVEL LOW MOVING NE FROM TX THROUGH THE LOWER/MID MS VLY BY
LATE AFTERNOON/EARLY EVENING. COLD TEMPERATURES ARE A CONCERN TO
END THE WORK WEEK.

LIFT AND RESULTANT CLOUDS ARE INCREASING OVER EASTERN OK AND WESTERN
AR ATTM IN ADVANCE OF A STRONG UPPER LOW CENTERED OVER CNTRL TX
AT 07Z. WEAK RADAR RETURNS ARE OCCURRING AS FAR NORTH AS NE
OK...BUT DRY AIR IN THE LOWEST 0-3 KM IS LIMITING THE NORTHERN
EXTENT TO SFC PRECIP TO THE SOUTHEAST QUARTER OF OK. RADAR RETURNS
ARE ALSO INCREASING IN A NARROW BAND OVER EASTERN KS AHEAD OF A
NORTHERN STREAM SHORTWAVE...BUT AGAIN PRECIP REACHING THE GROUND
WILL BE LIMITED BY LOW LEVEL DRY AIR. 

IN GENERAL...LARGE SCALE LIFT WILL INCREASE AFTER 12Z AND PEAK AT
18Z-21Z OVER THE EASTERN CWFA AS THE UPPER LOW MOVES THROUGH FAR
SOUTHEAST MO BOOT HEEL. LIFT OVER THE WESTERN CWFA WILL BE WEAKER
OVERALL...AND LIGHT PRECIPITATION FALLING TO INTO THE DRY LAYER
MAY NOT BE ENOUGH TO SATURATE THE LOWER LEVELS...ESPECIALLY SINCE
DRY AIR WILL CONTINUE TO BE PUMPED SOUTH INTO THE REGION TODAY.
OVER THE EASTERN CWFA...ESPECIALLY SOUTH CENTRAL MO...PROGGED GFS
CROSS SECTIONS INDICATE DEEP LIFT AND MORE ABUNDANT MOISTURE TO
PRODUCE GOOD CHANCES FOR RAIN. THE W-E GRADIENT OF RAINFALL
AMOUNTS WILL LIKELY BE FAIRLY ABRUPT. FOR POPS...HAVE NEARLY
90-100 POPS OVER SOUTH CENTRAL MO TO TEENS AND 20S OVER SOUTHEAST
KS FOR TODAY. PRECIP CHANCES RAPIDLY DECREASE OVER THE EASTERN
CWFA LATE THIS AFTERNOON AS THE UPPER LOW QUICKLY BEGIN TO EXIT
THE REGION. A DECENT PRESSURE GRADIENT WILL EXIST WEST OF THE
DEEPENING SFC LOW THIS AFTERNOON AND EVENING WITH BLUSTERY
CONDITIONS.

PRECIP TYPE IS STILL A CONCERN. WHERE LIFT/PRECIP CAN SATURATE THE
LOWER LEVELS...EVAPORATIVE COOLING AND GRADUALLY INCREASING COLD
AIR ADVECTION WILL HAVE A CHANCE TO TURN RAIN INTO WET SNOW IN
SOME PLACES DURING THE MID/LATE AFTERNOON. THE WINDOW FOR THIS IS
BRIEF AND NOT LOOKING FOR MUCH...IF ANY...IMPACT IN AREAS WHERE
SNOW CAN OCCUR.

COLD TEMPERATURES WILL BE THE MAIN STORY TO END THE WEEK. 850MB
TEMPS GENERALLY RANGE FROM -10 TO -12 DEG C THU AND FRI WITH SFC
TEMPERATURES STRUGGLING IN THE 30S FOR HIGHS. A WEAK SHORTWAVE WILL
MOVE THROUGH THE REGION FRI NIGHT AND A STRONGER SYSTEM WILL MOVE
THROUGH THE GULF COAST REGION AND SOUTHEAST U.S. OVER THE WEEKEND
WITH PRECIP REMAINING WELL TO THE SOUTH. WE WILL SEE A MODEST
WARM UP OVER THE WEEKEND AS A LOW AMPLITUDE UPPER RIDGE MOVES
THROUGH THE CNTRL PLAINS. A STRONGLY ZONAL MID LATITUDE UPPER FLOW
PATTERN WILL REMAIN ESTABLISHED OVER SOUTHERN CONUS. COULD SEE
SOME LIGHT SNOW OR RAIN SUNDAY NIGHT AS A QUICK MOVING SHORTWAVE
APPROACHES. DSA

&&

.AVIATION...

FOR THE 12Z TAFS...AN UPPER LEVEL LOW NOW OVER NE TEXAS WILL
CONTINUE TO TRACK NE THROUGH TODAY PASSING OVER THE BOOTHEAL OF
MISSOURI LATE IN THE DAY. THIS WILL HELP TO BRING INCREASING CLOUD
COVER AND LOWERING CEILINGS TO THE REGION AS THE DAY PROGRESSES.
EXPECT MVFR CONDITIONS TO DEVELOP NEAR 15Z FOR TERMINALS ACROSS
THE OZARKS AS LOW LEVEL MOISTURE SLOWLY INCREASES IN RESPONSE TO
THE STORM SYSTEM. A BRIEF PERIOD OF RAIN SNOW MIX OR RAIN CHANGING
TO SNOW WILL BE POSSIBLE THIS AFTERNOON ACCOMPANIED BY IFR
CEILINGS. THIS PERIOD WILL BE SHORT LIVED AS THE SYSTEM MOVES
QUICKLY EAST OF THE REGION. IMPROVING CONDITIONS WILL PROVIDE FOR
VFR CONDITIONS IN THE WAKE OF THE SYSTEM. 

HATCH

&&

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

$$