[LeArc] Forecast Discussion : MLI@ 2/12/03 3:22:52 PM

[learc@mailman.qth.net]

The following weather message is provided by McDonough County E.S.D.A.


FXUS63 KDVN 122130
AFDMLI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
330 PM CST WED FEB 12 2003

MAIN NEAR TERM CONCERN WILL BE TEMPS TONIGHT AND THURSDAY.  LITTLE 
IN THE WAY OF WX EXPECTED THROUGH THURSDAY AFTERNOON.  HIGH PRESSURE
RIDGE WAS IN PLACE OVER WESTERN IA/MN EARLY THIS AFTERNOON.  MODELS 
CONSISTENT MOVING CENTER OF HIGH ACROSS MO TONIGHT WHILE HOLDING 
RIDGE IN PLACE TO OUR WEST.  NW/SE ORIENTED RIDGE WILL BE OVER SRN 
SECTION OF CWA BY 12Z.  WINDS SHOULD DECOUPLE MOST AREAS.  EVEN NW 
IL WHERE GRADIENT IS A TIGHTER SHOULD SEE WINDS DIE OFF WITH LIGHT 
SNOW COVER HELPING TO ENHANCE LOW LEVEL COLD AIR.  BASED ON 
TRAJECTORIES AND EFFECTS OF SNOW COVER IN THE NORTHEAST...WILL GO AT 
OR A LITTLE BELOW THE COLDER MAV GUIDANCE.  TEMPS WARMED INTO THE 
LOW 30S NEAR RIDGE AXIS THIS AFTERNOON OVER NE/SD.  EXPECT THE SAME 
HERE ON THURSDAY AND WILL FAVOR THE COOLER MAV NUMBERS AGAIN.  

WX GETS PRETTY INTERSTING THURSDAY NIGHT INTO SATURDAY.  MODELS IN 
GENERAL AGREEMENT BRING SYSTEM OUT OF THE WESTERN U.S. THROUGH THE 
CENTRAL PLAINS AND MISSOURI BY SATURDAY.  HOWEVER ETA IS A LITTLE 
FURTHER SOUTH THAN THE GFS/UKMET.  BASED ON DISCUSSION FROM PREVIOUS 
SHIFT...THE GFS APPEARS TO HAVE CONTINUITY ON ITS SIDE AND WILL 
FAVOR. WILL BRING IN PCPN ON THE SW LATE THURSDAY NIGHT AND SPEAD 
OVER CWA FRIDAY. PCPN SHOULD END NORTH TO SOUTH FRIDAY NIGHT INTO 
SATURDAY MORNING. NORTH FLOW SUGGESTS AREAS NORTH OF HIGHWAY 30 WILL 
BE QUESTIONABLE FOR MEASURABLE PCPN AND WILL ONLY GO CHC POPS WHILE 
TO THE SOUTH WILL BUMP UP POPS TO LIKELY.  PRECIP TYPE LATE THURSDAY 
NIGHT INTO FRIDAY WILL BE THE BIG QUESTION.  SOUTHERN AND CENTRAL 
SECTIONS OF CWA WILL BE IN REGION OF OVERUNNING THROUGH 18Z FRIDAY.  
WILL BASE FORECAST ON AVN SOLUTION AND MENTION R/FZRA MIX FOR 
SOUTHERN MOST COUNTIES LATE THURSDAY NIGHT EARLY FRIDAY MORNING.  
BELIEVE AREAS JUST TO THE NORTH WILL SEE A S/FZRA MIX.  BY MID 
MORNING FRIDAY SURFACE TEMPS SHOULD WARM ENOUGH IN THE SOUTH TO 
CHANGE PCPN TO ALL RN WHILE AREAS JUST TO THE NORTH SHOULD 
EXPERIENCE R/ZR/S.  BELIEVE MOST OF CWA WILL BE FAR ENOUGH INTO THE 
WARM AIR TO LIMIT ICE AMOUNTS AND WILL HOLD OFF ON HEADLINES.  AT 
THIS POINT IT LOOKS LIKE IT MAY WARRANT AN ADVISORY AT BEST. BY 
FRIDAY AFTERNOON LOW LEVEL FLOW BACKS TO A MORE NERLY DIRECTION AND 
PULLS IN COLDER AIR...CHANINGING PCPN TO ALL SN FROM N TO S.  GFS 
SUGGESTS SNOW TO LINGER OF THE SOUTHERN MOST COUNTIES INTO SATURDAY 
MORNING.  

UPPER FLOW TRANSITIONS TO ZONAL DURING THE PERIOD.  GFS/UKMET DEPICT 
A STRONG SURFACE LOW OVER THE NORTHERN PLAINS BY MONDAY WITH GFS 
MOVING LOW INTO GREAT LAKES BY LATE TUESDAY AND SWINGING COLD FRONT 
THROUGH CWA DURING THE DAY TUESDAY.  TIMING WILL BE CRITICAL FOR 
TEMPS...BUT SO FAR GFS WHICH IS SUPPORTED BY UKMET BRINGS FRONT 
THROUGH EARLY IN THE DAY...SO WON'T STRAY TOO FAR FROM MEX NUMBERS. 
HIGH PRESSURE RIDGE OVER GULF COAST WILL BLOCK MOISTURE RETURN AND 
WOULD EXPECT ANY PCPN TO BE FURTHER NORTH CLOSER TO BETTER U/A 
SUPPORT.   NEXT SYSTEM PROGGED THROUGH THE REGION WEDNESDAY.  GFS 
DEPICTS SURFACE LOWS MOVING ALONG THE CANADIAN BORDER AND THORUGH 
THE SOUTHERN PLAINS AND LOWER MS VALLEY. GFS SHOWS CWA ON NORTHERN 
FRINGE OF SOUTHERN SYSTEMS PCPN SHIELD AND WILL INTRODUCE CHANCE OF 
SN FOR WEDNESDAY. 

THANKS TO ILX...LOT AND DMX FOR COORDINATION

.DVN...
IA...NONE.
IL...NONE.
MO...NONE.

$$

DLF