[LeArc] Forecast Discussion : MLI@ 6/21/2003 9:25:13 AM

[learc@mailman.qth.net]

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


FXUS63 KDVN 211423
AFDMLI

AREA FORECAST DISCUSSION...RETRANSMISSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
400 AM CDT SAT JUN 21 2003

LAST OF COOL AND COMFORTABLE NIGHTS WINDING DOWN AS CWA STILL UNDER 
INFLUENCE OF CANADIAN HIGH CENTERED OVER SOUTHERN LAKE MI. 
TEMPERATURES STILL SHORT TERM FORECAST CHALLENGE...THEN TSRA CHANCES 
FROM SUNDAY ONWARD AS WESTERN TROUGH FEEDS GULF MOISTURE INTO AREA 
WITH RETURN OF JUNE HEAT AS WELL. 

DRY AIR AND DRY GROUND ALLOWED DIURNAL SWING OF 35 TO 40 DEG 
FRIDAY...BUT GRADUALLY RISING DEWPOINTS AS DAY WEARS ON WILL DAMPER 
THIS SOME TODAY. COUNTERACTING THIS WILL BE WARMER START BY AT LEAST 
5 TO 10 DEG THIS MORNING ALONG WITH DEVELOPING LOW LEVEL WARM AIR 
ADVECTION...ESPECIALLY IN SOUTH LATE. WITH THIS IN MIND...TRENDED 
CLOSE TO MAV NUMBERS IN LOW TO MID 80S. TONIGHT...WARM AIR ADVECTION 
STARTS TO KICK IN AT H85...BUT THETA E RIDGE AXIS REMAINS WELL TO 
WEST ALONG MO RIVER NORTHEAST INTO CENTRAL MN. WILL HAVE SIGNIFICANT 
EAST TO WEST TEMPERATURE GRADIENT WITH WEAKER FLOW IN EAST ALLOWING 
SOME DECOUPLING AND FAVORED COOLER ETA MOS GUIDANCE WITH MID 50S 
EAST TO LOWER 60S WEST. GUIDANCE DEPICTS SOME WEAK FORCING AND LOW 
QPF TONIGHT WITH VORT MAX SWEEPING THROUGH IN SW FLOW...BUT LACK OF 
SURFACE CONVERGENCE AND BEST WAA AT H85 TO WEST SHOULD KEEP ANY 
NOCTURNAL CONVECTION WELL TO NORTHWEST UNTIL SUNDAY AFTERNOON WHEN 
SLIGHT CHANCE POPS KEPT IN FAR WEST WHERE SURFACE DEWPOINTS HIGHEST 
AND ALSO WHERE BETTER CHANCE OF REACHING CONVECTIVE TEMPERATURE. 
CONTINUED EAST TO WEST TEMPERATURE GRADIENT...ANTICIPATING ABOUT 5 
DEGREES WARMER THAN SATURDAY DUE TO WARMER START AND CONTINUED WARM 
ADVECTION. SUNDAY NIGHT...KEPT SCATTERED POPS OVER EASTERN IA AND 
SLIGHT CHANCE ELSEWHERE AS AREA MAY GET BRUSHED BY MCS LATE. 

SHEETS...

...MONDAY THROUGH FRIDAY...
THERE WILL BE SEVERAL CHANCES FOR PRECIP DURING THE PERIOD.  A TROF 
AXIS WILL SIT ACROSS NEBRASKA INTO MINNESOTA THRU TUESDAY...WITH A 
CHANCE OF MAINLY LATE NIGHT CONVECTION EACH NIGHT...THE BEST CHANCE 
BEING MONDAY NIGHT...WITH AN MCS MOVING IN FROM CENTRAL OR NORTH 
CENTRAL IOWA.  THE MEDIUM-RANGE MODELS AGREE ON A COLD FRONT 
WEDNESDAY MORNING...PRECEEDED BY CONVECTION TUESDAY NIGHT...AND A 
SECOND COLD FRONT FRIDAY.  ALL IN ALL...COULD PROVIDE SOME RELIEF 
FROM PRECIP DEFICITS WE'RE CURRENTLY RUNNING.  

LITTLE CHANGE FROM PREVIOUS FORECAST FOR PRECIP. TUESDAY'S CHANCES 
COULD BE QUESTIONABLE...AND MAY NEED TO BE LOOKED AT.  LOWERED THE 
TEMPS A NOTCH FOR COLD FRONTS FOR THE PERIOD WEDNESDAY THRU 
FRIDAY...BUT MAY NEED TO BE COOLED OFF FURTHER.  

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

$$