[LeArc] Forecast Discussion : MLI@ 6/20/2003 4:44:25 AM

[learc@mailman.qth.net]

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


FXUS63 KDVN 200942
AFDMLI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
320 AM CDT FRI JUN 20 2003

COOL CANADIAN HIGH PRESSURE CENTERED OVER NORTHERN WISCONSIN 
USHERING IN UNSEASONABLY COOL AND DRY AIRMASS INTO CWA THIS MORNING 
WITH TEMPERATURES ON TRACK TO NEAR RECORD VALUES IN MID 40S THIS 
MORNING. AT UPPER LEVELS...SHARP WAS FROM OK TO ONTARIO AT 00Z WITH 
SHARP POSITIVE TILT TROUGH TO EAST AND ANOTHER MOVING INTO THE WEST 
COAST. TEMPERATURES MAIN SHORT TERM FORECAST CHALLENGE AS RIDGE AT 
SURFACE AND ALOFT REMAINS IN CONTROL INTO EARLY SATURDAY...THEN 
RETURN WITH WARMER AIR AND HUMIDITY DEVELOPS OVER WEEKEND. 

VERY DRY AIRMASS...WITH DEWPOINTS ONLY IN 30S OVER EASTERN HALF 
CWA...WILL RECOVER QUICKLY UNDER FULL JUNE SUNSHINE AS CENTER OF 
SURFACE HIGH MOVES TO SOUTHERN LAKE MICHIGAN BY THIS EVENING.  
MIXING OUT TO H85 PUSHES HIGHS CLOSE TO 80 WHICH IS CLOSE TO GOING 
FORECAST AND MAV NUMBERS. TONIGHT...THE SURFACE RIDGE MOVES 
LITTLE...BUT TIGHTENING PRESSURE GRADIENT IN RESPONSE TO DEVELOPING 
LEE TROUGH WILL RESULT IN SOUTHERLY FLOW TOWARD MORNING. THIS WILL 
LIMIT DROP OFF TO LOW 50S...AT LOW END OF MOS GUIDANCE. GOING HIGHS 
IN LOW TO MID 80S FOR SATURDAY LOOK GOOD WITH INCREASE IN HUMIDITY 
AND MORE HIGH LEVEL CLOUDS COUNTER ACTING LOW LEVEL WARM AIR 
ADVECTION. STRONG H85 WARM AIR ADVECTION AFFECTS MAINLY WESTERN IA 
SATURDAY NIGHT...BUT WITH INCREASING DIVERGENT FLOW ALOFT...COULD 
SEE SOME NOCTURNAL CONVECTION DRIFTING INTO FAR WESTERN ZONES BEFORE 
FIZZLING AND THUS LIMITED SLIGHT CHANCE POPS TO MAINLY WEST OF 
HIGHWAY 218.   SHEETS...    

...SUNDAY THROUGH THURSDAY...
AT 500MB A RIDGE GIVES WAY TO SOUTHWEST FLOW SUNDAY NIGHT OR 
MONDAY...AND CONTINUES INTO THURSDAY WHEN A SHORT WAVE MOVES OVER. 
AT THE SURFACE SOUTHERLY FLOW DEVELOPS SUNDAY ACROSS THE FORECAST 
AREA AS THE HIGH SHIFTS EAST.  A WEAK WARM FRONT MAY LIFT ACROSS THE 
AREA MONDAY...PROVIDING A FOCUS FOR CONVECTION.  ADDITIONAL PRECIP 
IS POSSIBLE MONDAY NIGHT DUE TO DEBRIS FROM THE WEST.  PRECIP WILL 
BE POSSIBLE AGAIN NORTHWEST ON TUESDAY AS A SURFACE WAVE CLIPS THE 
AREA.  THROUGHOUT THIS PERIOD...SUNDAY THROUGH TUESDAY...THE MAIN 
DYNAMICS AND THETA-E AXIS WILL STAY JUST WEST OF THE AREA...FROM 
KANSAS INTO WESTERN AND CENTRAL IOWA...AND INTO MINNESOTA. DEW 
POINTS WILL BE UP THOUGH ACROSS THE DVN AREA...ESPECIALLY MONDAY 
THROUGH WEDNESDAY.  ON WEDNESDAY THE MEDIUM RANGE MODELS AGREE ON A 
COLD FRONT SWEEPING ACROSS THE REGION...BRINGING COOLER TEMPERATURES 
FOR THURSDAY.  WILL MAKE ONLY MINOR CHANGES TO ONGOING FORECAST AS 
IS CURRENTLY ON TRACK.  REA...

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

$$