[LeArc] Forecast Discussion : MLI@ 8/3/02 2:51:54 AM

[learc@mailman.qth.net]

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


FXUS63 KDVN 030754
AFDMLI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
253 AM CDT SAT AUG 3 2002

250 AND 500 HEIGHTS STILL SHOWING SOMEWHAT OF A FLAT UPPER PATTERN
WITH BEST JET ENERGY ALONG THE U.S. CANADIAN BORDER.  BEST PRESSURE
RISES INDICATED OVER NORTH DAKOTA AND NORTHERN MINNESOTA SO THIS IS
WHERE I WOULD LOOK FOR RIDGING TO INCREASE.  AT THE SURFACE...COLD
FRONT TO OUR SOUTH HAS PRETTY MUCH STALLED ACROSS NORTH
MISSOURI AND SOUTHERN ILLINOIS.  SATELLITE WAS SHOWING A NARROW BAND
OF CLOUDS BETWEEN 3 AND 4 THOUSAND FEET MOVING ACROSS THE FORECAST
AREA FROM THE SOUTHEAST...PROBABLY CAUGHT IN THE FLOW AROUND SURFACE
HIGH OFF TO THE EAST.

MAIN FORECAST CHALLENGE IN THE NEAR TERM WILL BE PLACEMENT AND TIMING
OF RAIN SATURDAY NIGHT.  LATER IN THE PACKAGE WILL LIKELY BUMP
TEMPERATURES UP TO COME IN LINE WITH WARM RETURN FLOW ON THURSDAY AND
FRIDAY.  LOOKING AT NEIGHBORING NWS OFFICES USING INTERSITE
COORDINATION MODE...SHOWS WE ARE PROBABLY ALREADY RUNNING AROUND 5
DEGREES ON THE COOL SIDE.  WITH THIS TYPE OF PROGRESSIVE FLOW OVER
THE UPPER RIDGE...EXPECT A SERIES OF DIFFICULT TO PINPOINT SHORT
WAVES TO PRODUCE MAINLY AFTERNOON AND NOCTURNAL THUNDERSTORMS ALONG
THE SURFACE FRONT THAT WILL BE DRAPED ACROSS OUR FORECAST AREA...FROM
WEST TO EAST...ESPECIALLY SUNDAY THROUGH MONDAY NIGHT.

MODELS ARE SOMEWHAT IN AGREEMENT WITH THE GENERAL PATTERN AND NO BIG
CHANGES TO LONG WAVE PATTERN EXPECTED THROUGH MUCH OF NEXT WEEK.
MODELS DO DIFFER SOMEWHAT ON HOW MUCH TROUGH AMPLIFICATION OCCURS
ACROSS THE CENTRAL U.S.  THE LATEST AVN HAS BACKED OFF A LITTLE FROM
LAST NIGHTS RUN.

EVERYTHING IS STILL POINTING TOWARD A SIGNIFICANT RAINFALL EVENT...
PROBABLY SOME SEVERE THUNDERSTORMS...ACROSS THE UPPER MISSISSIPPI
VALLEY.  STRENGTHENING LOW LEVEL FLOW...ALREADY EVIDENT ACROSS THE
CENTRAL PLAINS...WILL BRING HIGHER DEW POINT AIR INTO FAVORABLE
LOCATION OF SURFACE CONVERGENCE AND UPPER LEVEL DIVERGENT FLOW.
SATURDAY NIGHT INTO SUNDAY MORNING INDICATIONS ARE SOUTHERN MINNESOTA
AND CENTRAL WISCONSIN WILL BE THE MOST FAVORABLE AREA.  WITH THAT
SAID...OUR NORTH ZONES ARE CLOSE ENOUGH THAT WILL NEED TO MAINTAIN
THE GOING WORDING OF THUNDERSTORMS AND 40 POPS. AS SURFACE FRONT SAGS
SOUTH ACROSS OUR FORECAST AREA SUNDAY...PIECES OF SHORT WAVE ENERGY
WILL MOVE OVER THE TOP BRINGING BETTER SHOT OF THUNDERSTORMS TO OUR
FORECAST AREA SUNDAY THROUGH MONDAY.

NO BIG CHANGES TO THE EXTENDED FORECAST.  WILL PROBABLY BUMP HIGH
TEMPERATURES UP FROM LOW AND MID 80S TO MID AND UPPER 80S FOR
THURSDAY AND FRIDAY.

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

MEYER