[LeArc] Forecast Discussion : MLI@ 8/2/02 2:15:30 AM

[learc@mailman.qth.net]

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


FXUS63 KDVN 020712
AFDMLI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
212 AM CDT FRI AUG 2 2002

LATEST UPPER AIR ANALYSIS CONTINUES TO SHOW ZONAL FLOW ACROSS
NORTHERN U.S. WITH FAST MOVING SHORT WAVE EAST OF LAKE MICHIGAN AND
NEXT WAVE DIGGING INTO THE PACIFIC NORTHWEST.  LATEST SURFACE
ANALYSIS AND MSAS DATA SHOW THE COLD FRONT HAS NOW PUSHED EAST OF OUR
WARNING AND FORECAST AREA. POCKET OF +14 AIR AT 700 MB OVER OUR
REGION WAS PRIMARY INHIBITOR OF LAST NIGHTS CONVECTION. A TYPICAL
TRANSITIONAL AIR MASS ON THE BACK SIDE OF THE COLD FRONT WITH COOLER
AND DRYER AIR CONTINUING TO SETTLE ACROSS THE MIDWEST TODAY.

CHALLENGES IN THE SHORT TERM WILL DEAL MAINLY WITH SATURDAY...TIMING
OF NEXT SHOT OF THUNDERSTORMS AND RETURN OF WARM AIR.  ON SUNDAY
WILL NEED TO DETERMINE IF THE FRONT WILL HANG OUT TO THE NORTH OF
OUR FORECAST AREA...THEN APPEARS IT MAY BACK DOOR INTO OUR AREA
MONDAY AND TUESDAY.

MODELS HAVE BEEN ALL OVER THE PLACE FROM RUN TO RUN.  PREVIOUS RUN
HAD INDICATED THAT UPPER DIFFLUENT FLOW WOULD DEVELOP OVER FORECAST
AREA...WHICH OCCURRED OVER MICHIGAN AND OHIO INSTEAD OF ILLINOIS.
ETA/AVN HAS NOW COME BACK...INITIALIZED...CLOSE TO ANALYSIS AT 00Z.
MOISTURE FIELDS DO NOT SEEM TO MATCH WELL WITH THE BEST SURFACE AND
UPPER CONVERGENCE PATTERN AFTER SUNDAY.

FOR SATURDAY WILL LEAVE THE SLIGHT CHANCE WORDING FOR NOW BUT APPEARS
BEST CHANCE FOR SHOWERS AND THUNDERSTORMS WILL BE NORTH AND WEST
ZONES.

SATURDAY NIGHT INTO TUESDAY...HIGHER RH FIELDS LAY OUT ACROSS
THE MIDWEST.  SURFACE FEATURES NOT OVERLY IMPRESSIVE WITH WEST TO
EAST STATIONARY BOUNDARY FORECAST TO DEVELOP.  HOWEVER...UPPER LEVEL
RIDGE RIDER SHORT WAVES WILL TAKE TURNS MOVING ACROSS THE AREA...AND
THIS TIME 700 MB TEMPERATURES ARE FORECAST TO BE +10 OR LESS...SO NOT
MUCH OF A CAP.  WILL LEAVE TUESDAY DRY FOR NOW...BUT IF SURFACE FRONT
STALLS OUT ACROSS FORECAST AREA AS ADVERTISED...MAY HAVE TO BRING IN
SOME POPS LATER.  TEMPERATURES WILL ALSO BE TRICKY FROM ONE SIDE OF
THE FRONT TO THE OTHER.  SEE NO REASON TO MAKE ANY CHANGES TO LATE
PERIODS OF THE EXTENDED FORECAST.

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

MEYER