[LeArc] Forecast Discussion : MLI@ 8/19/02 1:46:44 PM

[learc@mailman.qth.net]

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


FXUS63 KDVN 191849
AFDMLI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
149 PM CDT MON AUG 19 2002

SYNOPSIS...
MCS HAS EXITED THE CWA EARLY TODAY...AS UPPER LEVEL FORCING AND
EXCELLENT DIFFLUENCE MOVES EAST.  HIGH PRESSURE OVER SOUTH DAKOTA IS NOW
FILLING INTO THE AREA...WITH CLEARING SKIES AND MUCH LOWER HUMIDITY.
ALL IN ALL...TODAY WILL SHAPE UP TO BE A GREAT DAY OUTDOORS. LOOKING
OUTSIDE THE MIDWEST...MONSOON FLOW OVER THE SOUTHWEST CONTINUES TO BE
ACTIVE. FAIRLY STRONG WAVE EMBEDDED IN THE FLOW NOTED OVER SOUTHERN
CALIFORNIA. THIS WAVE IS BEGINNING TO BE KICKED OUT AS MORE SIGNIFICANT
500MB WAVE MOVES INTO THE PACIFIC NORTHWEST.  THE INTERACTION OF THESE
TWO FEATURES WILL BE A MAJOR PLAYER IN THE NEXT 48 HOURS OF WEATHER.

SHORT TERM...
HIGH PRESSURE WILL BE FOUND ACROSS THE CWA OVERNIGHT TONIGHT.  WILL
ANTICIPATE FOG TO FORM OVERNIGHT...ESPECIALLY ACROSS THE SOUTHERN HALF
OF THE CWA...WHERE HEAVY PRECIP HAS FALLEN THIS MORNING.  THE HIGH
CONTINUES TO MOVE EAST TUESDAY...WITH SOUTHEAST FLOW RETURNING TO THE
AREA DURING THE MORNING.  THE WAVE MOVING UP FROM THE MONSOONAL FLOW
WILL BECOME ACTIVE AS IT INTERACTS WITH THE STATIONARY FRONT OVER THE
CENTRAL PLAINS TONIGHT AND TUESDAY.  THE BIG QUESTION IS WEATHER THIS
WILL RIDE NORTH OF THE AREA TUESDAY NIGHT...AS ADVERTISED BY THE ETA...
OR COME CRASHING THROUGH THE NORTHERN HALF OF THE CWA PER THE NGM. AVN
BRINGS THIS FEATURE ACROSS THE IOWA MINNESOTA BORDER TUESDAY EVENING.
CONVECTIVE TRENDS TONIGHT WILL BE IMPORTANT IN PLACEMENT OF THE EAST-
WEST BOUNDARY TUESDAY EVENING. AT THIS POINT...I FEEL THE BEST FORCING
FOR NOCTURNAL CONVECTION WILL BE FOUND ALONG THE FAR NORTHWEST CWA AND
UP THROUGH SOUTHERN MINNESOTA.  HOWEVER...CONVERGENT FLOW AT THE SURFACE
AND MARGINAL PVA AT 500MB WILL BRING ENOUGH OF A THREAT OF SURFACED
BASED CONVECTION TO WARRANT CHANCE PRECIP ACROSS THE ENTIRE CWA.  BEST
CHANCES WILL BE FOUND IN THE NORTH AND WEST...WITH SMALL POPS IN THE
SOUTH AND EAST. WEDNESDAY...AM EXPECTING A DRY DAY OVER THE AREA.  AVN
SHIFTS BOUNDARY SOUTH INTO THE CWA DURING THE EVENING.  CONFIDENCE ON
THIS IS NOT HIGH SINCE UPPER WAVE APPROACHING FROM THE WEST WILL LIKE
KEEP THE FRONT STATIONARY TO THE NORTH. UKMET IS ALSO ON TRACK WITH THIS
SOLUTION...THEREFORE WILL ADD CHANCE POPS FOR THE AREA ALONG AND NORTH
OF I80 WEDNESDAY EVENING.


EXTENDED...
REX BLOCK PATTERN IN THE WESTERN US WILL CONTINUE THROUGH THE END OF
THE WORK-WEEK.   BY THURSDAY NIGHT...A SHORT WAVE IS EXPECTED TO EJECT
OUT OF THE SLOW MOVING UPPER LOW OUT WEST. THIS WILL LIKELY FOCUS A
SIGNIFICANT ROUND OF PRECIP ALONG THE BOUNDARY DURING THE EVENING AND
OVERNIGHT.  WHILE THIS WILL LIKELY FIRE NORTH OF THE CWA...PROPAGATION
TO THE SOUTHEAST IS EXPECTED.  THEREFORE...WILL KEEP WORDING OF PRECIP
TO LATE THURSDAY.  FRIDAY...A STRONG SHORT WAVE WILL OVER-TOP THE
BLOCKING PATTERN IN THE WEST.  A SEASONALLY STRONG COLD FRONT WILL DIVE
SOUTH FROM MANITOBA. 00Z AVN BRINGS THIS THROUGH THE CWA FRIDAY
EVENING...PROVIDING A GOOD CHANCE OF PRECIPITATION. 850MB TEMPERATURES
DROP INTO THE UPPER SINGLE DIGITS SATURDAY...SO GOOD COOL DOWN IS LIKELY
FOR THE UPCOMING WEEKEND.  DRY WEATHER WITH MODERATING TEMPERATURES ARE
EXPECTED FOR THE REMAINDER OF THE WEEKEND AND MONDAY.



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

ERVIN