FXUS63 KSGF 240911
AFDSGF

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE SPRINGFIELD MO
311 AM CST THU DEC 24 2009

.DISCUSSION...

FORECAST CHALLENGES CONTINUE TO DEAL WITH HEAVY RAINS/FLASH FLOOD
POTENTIAL TODAY...FOLLOWED BY WINTER WEATHER CONDITIONS THIS
EVENING AND TEMPERATURES THROUGH THE WEEKEND.

CURRENTLY...SURFACE COLD FRONT KNOCKING ON THE DOOR...CURRENTLY
EXTENDING FROM A SURFACE LOW OVER NORTHWEST MISSOURI...EXTENDING
SOUTHWEST TO A SECOND SURFACE LOW LOCATED IN EASTERN OKLAHOMA
THIS MORNING. UPPER SHORTWAVE CURRENTLY OVER SOUTHWEST
TEXAS...MOVING SLOWLY TO THE NORTHEAST. TO OUR SOUTH AND
EAST...SIGNIFICANT GULF MOISTURE CONTINUES TO PUMP NORTH WITH
WIDESPREAD MODERATE RAINS OVER MUCH OF ARKANSAS...MOVING INTO
SOUTHEASTERN MISSOURI THIS MORNING. WILL CONTINUE THE FLASH FLOOD
WATCH FOR OUR SOUTHEASTERN COUNTIES TO ACCOUNT FOR THIS
SIGNIFICANT RAINFALL HEADING THAT WAY.

FOR TODAY...SOME MODELS DIFFERENCES IN REFERENCE TO THE MOVEMENT
OF THE SYSTEM OVER TEXAS. WRF MOVES THE SYSTEM FURTHER EAST WITH
HEAVIER SNOWS MOVING INTO OUR EASTERN COUNTIES...AS WELL AS NORTHEASTERN
MISSOURI AND SOUTHERN ILLINOIS. GFS...WHICH HAS BEEN MORE
CONSISTENT OVER THE PAST FEW DAYS...KEEPS SYSTEM FURTHER WEST. THE
NEW ECMWF ALSO SUPPORTS THIS SOLUTION FURTHER WEST...SO HAVE
TRENDED FORECAST MORE IN LINE WITH THE GFS TODAY. GFS BRINGS THE
SOUTHERN LOW INTO SOUTH CENTRAL MISSOURI THIS AFTERNOON...WITH
COLDER AIR WRAPPING INTO THE LOW FROM THE NORTHWEST BY MID
AFTERNOON. 850MB TEMPERATURES FALL QUITE RAPIDLY THIS
AFTERNOON...FALLING FROM +6C THIS MORNING TO -8C BY EARLY
EVENING ACROSS SOUTHWEST MISSOURI AND SOUTHEAST KANSAS...A 25
DEGREE F DROP IN LOW LEVEL TEMPERATURES FOR OUR WESTERN COUNTIES.
SIGNIFICANT UPGLIDE SEEN ON ISENTROPIC SURFACES ACROSS WESTERN
MISSOURI IN THE TROWAL FEATURE THAT SETS UP BEHIND THE LOW. THERE
IS GOING TO BE A BRIEF WINDOW...SAY FROM 00Z THIS AFTERNOON TO
MAYBE 12Z CHRISTMAS DAY...WHERE WE BELIEVE THERE IS GOING TO BE
SUBSTANTIAL SNOWFALL ACROSS OUR WESTERN HALF OF THE CWA. WITH
850MB TEMPERATURES RAPIDLY FALLING THROUGH THE EVENING AS 850MB
TEMPERATURES FALL TO -13C BY 12Z FRIDAY. SURFACE WINDS WILL BE
QUITE GUSTY AS WELL FROM THE NORTHWEST AS WE SEE A 25MB PRESSURE
GRADIENT SETTING UP FROM THE SURFACE LOW CENTER OUT TO WICHITA
KANSAS. THESE STRONG WINDS...COMBINED WITH SNOW ACCUMULATIONS OF 4
TO 8 INCHES POSSIBLE...LED US TO ISSUE A WINTER STORM WARNING FOR
COUNTIES WEST OF A LINE FROM CASSVILLE TO SPRINGFIELD TO
VERSAILLES FOR THIS EVENING THROUGH FRIDAY AFTERNOON. SNOW SHOULD
RAPIDLY DECREASE DURING THE MORNING HOURS CHRISTMAS DAY...BUT WITH
THE GUSTY NORTHWEST WINDS CONTINUING...DECIDED TO ERR ON THE SIDE
OF SAFETY AND KEEP THE WARNING GOING THROUGH THE AFTERNOON HOURS
AS BLOWING AND DRIFTING SNOW WILL BE COMMON. FURTHER
EAST...DECIDED TO GO WITH A WINTER WEATHER ADVISORY AS THESE AREAS
WILL SEE A LESSER AMOUNT OF SNOW FALL AS THE SYSTEM PULLS TO THE
NORTHEAST AND COLDER AIR WILL BE DELAYED SOME THIS EVENING. DAY
SHIFT MAY NEED TO ADD A FEW MORE COUNTIES TO THE WARNING SHOULD
THE TROWAL SHIFT FURTHER EAST AS THE WRF SUGGESTS.

BY FRIDAY AFTERNOON...MAJORITY OF PRECIPITATION SHOULD SHIFT TO
THE NORTH AS THE LOW CONTINUES TO MOVE INTO IOWA. COLD AIR WILL
STILL BE IN PLACE ALONG WITH GUSTY NORTHWEST WINDS OVERNIGHT INTO
SATURDAY. TEMPERATURES ARE GOING TO BE VERY COLD AND HAVE UNDERCUT
GUIDANCE ON TEMPERATURES FOR BOTH SATURDAY MORNING AND AFTERNOON.

COLD AIR TO STAY IN PLACE THROUGH THE WEEKEND WITH 850MB
TEMPERATURES STAYING IN THE NEGATIVE DOUBLE DIGITS. A STRATUS DECK
SHOULD REMAIN IN PLACE AS WELL IN THE CYCLONIC NORTHWESTERLY FLOW
TO LIMIT ANY SUNSHINE...SO CONTINUED UNDERCUTTING GUIDANCE ON
TEMPERATURES THROUGH THE WEEKEND. THE WAY IT LOOKS...WE SHOULD
CONTINUE TO SEE BELOW NORMAL TEMPERATURES IN THE NORTHWEST FLOW
UNTIL AT LEAST TUESDAY...WHEN WINDS SHIFT TO A MORE WESTERLY DIRECTION.

CLAYCOMB

&&

.AVIATION...

FOR THE 0600Z KSGF/KJLN/KBBG TAFS...LOW PRESSURE WILL APPROACH THE
REGION FROM THE SOUTHWEST. PREDOMINATELY IFR CEILINGS ARE
EXPECTED...ESPECIALLY WEST OF A SHARPENING SFC TROUGH EXPECTED TO
MIGRATE EAST INTO THE AREA OVERNIGHT. THE VISIBILITY WILL LIKELY
BE QUITE VARIABLE IN DRIZZLE/FOG/LIGHT RAIN...HEAVIER PRECIPITATION
WILL GENERALLY BE EAST OF THE TAF SITES OVER THE NEXT SEVERAL
HOURS. A BAND OF SNOW WILL DEVELOP SOMEWHERE WEST OF THE LOW
CENTER AS IT MOVES THROUGH MO THU EVENING. EXPECT PRECIP TO CHANGE
OVER TO SNOW FROM WEST TO EAST ALONG WITH STRONG N-NW WIND GUSTS.

DSA

&&

.SGF WATCHES/WARNINGS/ADVISORIES...
MO...WINTER WEATHER ADVISORY FROM 9 PM THIS EVENING TO 6 PM CST 
     FRIDAY FOR MOZ057-058-070-071-081>083-091-092-096>098-
     104>106.

     FLASH FLOOD WATCH THROUGH THIS AFTERNOON FOR MOZ057-058-069>071-
     080>083-090>092-095>098-102>106.

     WINTER STORM WARNING FROM 6 PM THIS EVENING TO 6 PM CST FRIDAY 
     FOR MOZ055-056-067>069-078>080-088>090-093>095-101>103.

     WINTER STORM WARNING FROM 3 PM THIS AFTERNOON TO 6 PM CST FRIDAY 
     FOR MOZ066-077.

KS...WINTER STORM WARNING FROM 3 PM THIS AFTERNOON TO 6 PM CST FRIDAY 
     FOR KSZ073-097-101.

&&

$$