[LeArc] Forecast Discussion : MLI@ 11/5/02 1:54:32 AM

[learc@mailman.qth.net]

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


FXUS63 KDVN 050804
AFDMLI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
200 AM CST TUE NOV 5 2002

.OVERVIEW...DEEP TROUGH OVER ROCKY MOUNTAINS IS MOVING EAST WITH
STRONG 120-150+ KT JET AHEAD OF THIS TROUGH AND ANOTHER 125KT JET MAX
DIVING SOUTH.  AREA RADARS SHOW SWATH OF PRECIPITATION BREAKING OUT
AHEAD OF TROUGH IN PLAINS AND SFC OBS SHOW AT 07Z MAINLY SNOW ALONG
AND NORTH OF I-80 AND MIXED BAG OF SNOW/SLEET/RAIN SOUTH OF I-80 IN
IOWA WITH RAIN SOUTH OF THIS. AWIPS DISTANCE TIME FEATURE SUGGEST
PRECIPITATION TO REACH AREA BY 4 AM WEST LASTING UNTIL EARLY
AFTERNOON EAST OF MISSISSIPPI. UPPER AIR ANALYSIS SUPPORTS RAIN/SNOW
CHANGEOVER LINE TO SLOWLY MOVE NORTH DURING DAY AFTER SUNRISE DESPITE
EVAPORATIVE COOLING DUE TO WEAK TO MODERATE WAA ALOFT.

...PRECIPITATION TYPE TODAY AND POSSIBLE SNOW AMOUNTS FIRST PERIOD
CONCERN WITH CLEARING TONIGHT...THEN WEEKEND SYSTEM MID TERM ISSUE...

.DIAGNOSIS AND DAY 1-3...ETA VERIFIES BEST ON LOW LEVEL TEMPS AND
EXCEPTIONALLY WELL AT 07Z ON PRECIPITATION FIELDS SO MAIN TOOL ALONG
WITH NOWCAST TOOLS FOR FIRST PERIOD.  THIS SUPPORTS CATEGORICAL ALL
AREAS WITH MAINLY SNOW ALONG AND NORTH OF HIGHWAY 30 THIS AM WITH 1-
2 INCHES POSSIBLE IN GRASSY AREAS AS SFC TEMPS STAY AROUND 32F WITH
SFC GROUND TEMPS EXCEPTIONALLY COLD AT JUST ABOVE FREEZING AT OFFICE
DUE TO COLD TEMPS TODAY.  EXPECT CONDITIONS TO BE WORST NEAR MORNING
RUSH HOUR WITH SOME SLIPPERY ROADS POSSIBLE ALONG HIGHWAY 20 BUT
RIGHT NOW ADVISORY CRITERIA SHOULD NOT BE NEEDED. ALONG INTERSTATE 80
TRENDING TOWARD A MIXTURE OF SNOW/SLEET AND RAIN CHANGING TO RAIN BY
LATE MORNING BEFORE DIMINISHING TO MAINLY DRIZZLE LATE.  HIGHWAY 34
AND SOUTH MAINLY RAIN...POSSIBLY MIXED WITH SNOW AND SLEET EARLY.
TEMPS TODAY WILL GO ON LOW SIDE OR JUST ABOVE MET WITH PRECIPITATION
AND LOW CLOUDS ALL DAY.  TONIGHT...MAY SEE SOME AREAS OF FOG DUE TO
TRAPPED MOISTURE BUT PASS THIS TO DAY SHIFT TO EVALUATE AS FIRST
PERIOD PRECIP A PRIME PLAYER ON THIS HAPPENING. CLEARING NW 1/2 OR
MORE LATE TONIGHT WITH NW WINDS WITH LOW TEMPS JUST ABOVE GUIDANCE IN
CLOUDS. SIGNIFICANT WARMUP KICKS IN WED AND ESPECIALLY THU DUE TO
ZONAL FLOW ALOFT AND LOW LEVEL SOUTH SFC WINDS AS LEE SIDE TROUGH
DEVELOPS AHEAD OF 150+ KT JET CRASHING INTO WEST COAST.

EXTENDED (FRI-MON)...ALL MODELS SUGGEST PACIFIC ENERGY TO DEVELOP
MAJOR STORM IN CENTRAL US SAT/SUN WITH STRONG WAA AHEAD OF SYSTEM
FRI/SAT FOR VERY MILD TEMPS. LIKELY POPS REASONABLE SAT/SUN WITH RAIN
AS JET AXIS WELL SOUTH OF AREA FOR CAUSING STRATIFORMING PRECIP AS
LOW APPROACHES WITH SHRA/TSRA MORE FAVORABLE ALONG/SOUTH OF I-70.
LARGER SCALE PATTERN OF SYSTEM AND FORCING SUPPORT MODERATELY HIGH
CONFIDENCE OF SEASONABLY HEAVY AMOUNTS OF QPF AS LOW CRANKS UP THIS
WEEKEND BUT PHASING AND RESOLUTION ISSUES SHOULD TAKE ANOTHER 36 TO
48 TO COME BETTER IN FOCUS ON MEDIUM MODEL QPF FIELDS.

COORDINATED WITH ARX...THANKS.

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

NICHOLS