[LeArc] Forecast Discussion : MLI@ 11/21/02 1:22:47 PM

[learc@mailman.qth.net]

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


FXUS63 KDVN 211932
AFDMLI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
125 PM CST THU NOV 21 2002

.OVERVIEW...FAST NORTHWEST FLOW BISECTS AREA WITH ~100KT JET.  UPPER
ANALYSIS SUPPORTS JET MIGRATING EAST WITH MODERATE HEIGHT RISES
SUGGESTING CLEARING ACROSS REGION NEXT 6-18 HOURS.  LATEST SATELLITE
AND SFC ALSO SUPPORT THIS TREND WITH BACK EDGE OF CLEARING AT 18Z
ALONG MISSOURI RIVER BASIN.  LOSS OF SUNSHINE TONIGHT AND DOWNWARD
MOTION...CLEARING TO BE ENHANCED AS TROUGH MOVES EAST AS AREA COMES
UNDER ANTI-CYCLONIC SIDE OF JET. SFC PRESSURE RISE COUPLETS PORTEND
BRISK NW WINDS TO DECREASE AT OR JUST AFTER SUNSET.

TIMING CLEARING TONIGHT WITH TEMPS MAIN ISSUE...CHANCE OF SNOW THEN
SUNDAY AND AGAIN TUESDAY LONGER RANGE FORECAST ISSUES.

.DIAGNOSIS AND DAYS 1-3...MODELS HAVE NORMAL PROBLEMS ON LOW LEVEL
CLOUDS AND WILL SUPPLEMENT WITH NOWCAST TOOLS.  THIS SUGGESTS MOSTLY
CLOUDY MOST AREAS THIS EVENING WITH CLEARING TOWARD MIDNIGHT IN WEST
WITH EAST SECTIONS MORE TOWARD LATE OVERNIGHT HOURS.  NW WINDS OF 5
TO 10 MPH AND ONLY MODERATE CAA WILL TREND JUST ABOVE MODEL BLEND FOR
LOWS DUE TO CLOUDS AND SOME MIXING.  THEN SFC HIGH OVERHEAD WILL GO
JUST BELOW FWC/MET BLEND DUE TO LIMITED MIXING DESPITE MOSTLY SUNNY
SKIES.  LOWS FRIDAY NIGHT TO BE AROUND MIDNIGHT WITH STEADY TO SLOWLY
RISING TEMPS LATE AHEAD OF NEXT WAVE.  SATURDAY...WITH SW WINDS AND
FROPA LATE WILL GO ON HIGH SIDE FOR MAX TEMPS AS LIMITED MOISTURE
SUPPORTS DECENT WARMUP AHEAD OF ARCTIC AIR.  THEN...SLOW COOL DOWN AS
ARCTIC SAGS IN. CHANCE POPS SOUTH 1/2 LATE SUNDAY AND SUNDAY NIGHT
STILL WARRANTED DUE TO UNCERTAINTY OF WEAK WAVE AND FLURRIES IN
NORTHERN 1/2.  LARGER SCALE PATTERN FOR SUNDAY SUGGESTS LIMITED
ACCUMULATION OF SNOW THOUGH DUE TO MARGINAL FORCING AND MOISTURE.
WILL MAKE LATE DECISION IF NEED TO MENTION EVENING FLURRIES TONIGHT
BASED ON OBSERVATIONS AND RADAR TRENDS.

.EXTENDED (MON-THU)...LATEST UKMET SIMILAR TO GFS-AVN/NOGAPS OF LARGE
ARCTIC HIGH DOMINATING EARLY NEXT WEEK WITH TROUGH ON WEST COAST.
BELOW TO WELL NORMAL TEMPS IN STORE WITH CHANCE OF FLURRIES FOR NOW
ON TUESDAY WITH SHORT WAVE BRINGING REINFORCING SHOT OF COLDER AIR.
SOME QUESTION OF POPS ON THURSDAY WITH STRONGER NW SHORT WAVE BUT
POOR TIMING ISSUES WILL LEAVE OUT ANY POPS FOR NOW.

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

NICHOLS