[LeArc] Forecast Discussion : MLI@ 8/13/02 2:27:29 PM

[learc@mailman.qth.net]

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


FXUS63 KDVN 131929
AFDMLI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
230 PM CDT TUE AUG 13 2002

SYNOPSIS...
COLD FRONTAL PASSAGE UNDERWAY THIS MORNING...EFFECTIVELY ENDING THE
THREAT OF HEAVY RAIN ACROSS ALL BUT THE EXTREME EAST PORTION OF CWA
TODAY.  AS OF 15Z...THE FRONT WAS FOUND FROM NEAR DBQ TO IRK...AND
SLOWLY MOVING EAST.  A WAVE OF LOW PRESSURE...ADVERTISED BY THE PAST
RUNS OF THE AVN...WAS FORMING ALONG THE FRONT IN THE VCNTY OF IRK...AND
NOW SLOWLY MOVING NORTHEAST IN WARREN COUNTY ILLINOIS. THIS LOW WILL
MOVE ALONG THE FRONT...AND WILL BRING ANOTHER ROUND OF TSRA+
TO PLACES FURTHER EAST. POST FRONTAL STRATIFORM PRECIP NOW ACROSS
EASTERN IOWA WILL GRADUALLY END BY 03Z AS THE MAIN 500MB TROUGH AND
135KT JET ENTRANCE REGION SHIFTS EAST OF THE AREA. DEWPOINTS UPSTREAM
ACROSS WESTERN IOWA AND THE DAKOTAS HAVE FALLEN INTO THE 50S. LOOKING
FORWARD TO A COUPLE DAYS OFF FROM THE HIGH HUMIDITY LEVELS OF THE RECENT
DAYS! FURTHER UPSTREAM...IMPRESSIVE 80 M HIGHT FALLS AT 500MB NOTED OVER
NORTHERN ALBERTA ON THE NOSE OF 130 KT JET STREAK.  THIS FEATURE WILL
SHIFT EAST ALONG THE CANADIAN BORDER BY MID-WEEK.

SHORT TERM...
DRY WESTERLY FLOW AT SFC AND 850MB WILL PROVIDE FOR PLENTY OF SUNSHINE
BY WEDNESDAY AFTERNOON.  HIGH TEMPERATURES WILL REBOUND INTO THE UPPER
70S FAR NORTH...TO THE LOWER 80S SOUTH...GIVEN THE DRY AIR AND PARTLY
CLOUDY SKIES.  BY WEDNESDAY EVENING...FLOW BECOMES SOUTHWESTERLY AHEAD
OF APPROACHING WEAK COLD FRONT.  CONVERGENCE AND MOISTURE ALONG THIS
FRONT WILL BE MINIMAL ON THURSDAY...SO WILL KEEP FORECAST FOR MILD
CONDITIONS WITH PLENTY OF SUN GOING.

SOUTHERLY FLOW ON FRIDAY WILL BRING ANOTHER MILD DAY.  BY
MID-DAY...DEWPOINTS RETURN INTO THE UPPER 60S AND LOWER 70S...WHILE
850MB TEMPS FROM 16-18C SUPPORT AFTERNOON HIGHS IN THE MID-UPPER 80S.
MID LEVEL MOISTURE IS STILL ON THE LEAN SIDE...SO WILL GO WITH
PARTLY CLOUDY CONDITIONS.  FRIDAY EVENING...SOUTHERN PERIPHERY OF 500MB
WESTERLY FLOW...PROGRESSIVE TROUGH AT 850MB...ALONG WITH INCREASING
MOIST RETURN FLOW ON LLJ WILL PROVIDE A CHANCE OF ISOLATED CONVECTION
OVER NORTHERN SECTIONS OF THE CWA.

EXTENDED...
EXTENDED PERIOD OF SOUTHERLY FLOW AHEAD OF DEVELOPING 500MB TROUGH IN
THE NORTHWEST US BEGINS FRIDAY EVENING AND CONTINUES THROUGH TUESDAY.
MRF PLACES 850MB AND SURFACE BOUNDARY ALONG THE IOWA/MINNESOTA BORDER
EARLY SATURDAY...BEFORE MEANDERING SOUTHWARD THROUGH THE CWA OVER THE
WEEKEND AS 1018MB SURFACE HIGH BUILDS EAST ALONG THE CANADIAN BORDER.
NEW AVN WEAKER WITH THIS HIGH...AND PLACES THE BOUNDARY FURTHER NORTH.
AT THIS TIME...I WILL NOT REMOVE POPS FOR SATURDAY...THOUGH FUTURE
SHIFTS WILL NEED TO KEEP AN EYE ON THIS.  MRF PLACES THE CENTER OF THE
HIGH OVER THE CENTRAL AND EASTERN GREAT LAKES DURING THE WEEKEND. IF
CORRECT...A LAKE ENHANCED QUASI-STATIONARY BOUNDARY WILL LIKELY BE FOUND
FROM CENTRAL INDIANA...WEST TO SOUTHEAST IOWA...AND THEN NORTHWEST
TOWARD SIOUX FALLS SD. THIS SET UP WOULD PROVIDE A GOOD CHANCE OF
EVENING AND NOCTURNAL TSRA OVER THE WEEKEND. WESTERN 500MB TROUGH MAKES
ITS MOVE EAST SUNDAY. THIS WILL SWEEP A COLD FRONT INTO THE CWA
MONDAY...BUT UPPER ENERGY ROTATES NORTH MONDAY NIGHT...ALLOWING THE
FRONT TO HANG UP ACROSS THE AREA TUESDAY. CONFIDENCE ON FINE DETAILS AND
EXACT TIMING OF THIS ARE CERTAINLY NOT HIGH...THIS SETUP WILL AGAIN PUT
THE CWA IN POSITION FOR A DECENT CHANCE OF TSRA.



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

ERVIN