[LeArc] Forecast Discussion : MLI@ 11/22/02 3:25:52 PM

[learc@mailman.qth.net]

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


FXUS63 KDVN 222137
AFDMLI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
335 PM CST FRI NOV 22 2002

UPPER PATTERN SUGGESTS HIGH PROBABILITY OF SOME ACCUMULATING SNOWS IN COLD
AND ACTIVE REGIME NEXT 7-10 DAYS.

UPPER FLOW TO UNDERGO FURTHER AMPLIFICATION NEXT FEW DAYS. BIG MODEL
DISCREPANCIES ON FLOW REGIME...WITH ENSEMBLE MEMBERS 
OVERALL LENDING SUPPORT TO UKMET SOLUTION WITH STRONG CLOSED LOW DIVING
SOUTH THROUGH CALIFORNIA DURING PERIOD WHILE NORTHERN STREAM
DOMINATES CLOSE TO HOME. 

MAIN CONCERN IS WITH TEMPS NEAR TERM THEN CHC OF SNOW SUN AFTN AND EVE
FOLLOWED BY STRONGER SYSTEM FOR TUE.

NEAR TERM...SURFACE RIDGE TO SLIDE EAST TONIGHT. WINDS ALREADY BECOMING
SOUTHERLY IN THE WEST WITH WARM AIR APPROACHING CENTRAL IA 
PER OBS AND PROFILERS. WITH CLEAR SKIES...DRY AIR (EVIDENCE DEWPTS
IN UPPER TEENS TO AROUND 20 DEGS) AND LIGHT WINDS EXPECT TEMPS TO PLUNGE
THIS EVE. WILL GO COLDEST EAST (AT OR BELOW GUIDANCE) AND 
WARMEST IN THE WEST (NEAR BLEND OF GUIDANCE). ON SAT...COLD FRONT TO
SHIFT QUICKLY THROUGH DURING MORNING AND EARLY AFTN.
FRONT ACCOMPANIED BY SOME CLOUDINESS...BUT LOW LEVELS DRY AND FORCING
WELL NORTH IN GREAT LAKES NEAR SURFACE WAVE...SO NO PCPN.
TEMPS QUITE A CHALLENGE...AS REAL ARCTIC AIR LAGGING WELL BEHIND FRONT.
TEMPS WITH CHINOOK WINDS WARMING NICELY IN PLAINS. LAST CHECK
OF OBS SHOWED GLASGOW MT WITH CLOUDS AND BEING POST FRONTAL STILL AT 50 DEGS!
ALSO...TREND THIS FALL HAS BEEN FOR MODELS TO BE TOO AGRESSIVE ON
POST FRONTAL COOLING...SO WILL SIDE TOWARD WARMER FWC/ETA BLEND TACKING
ON FEW DEGS WITH ANTICIPATION OF SUNSHINE IN THE AFTN.
SAT WILL DEFINITELY BE THE "KEEPER" OF THE NEXT 5 OR SO DAYS...AS BOTTOM
FALLS OUT IN BIG WAY WITH ARTIC FRONT ARRIVING MIDNIGHT
SAT NIGHT INTO SUN. OVERRUNING SNOW EXPECTED ALONG FRONT TO OUR SOUTH ON SUN
WITH POTENTIAL FOR THIS TO AFFECT AT LEAST SOUTHERN 1/3RD WITH
MAINLY FLURRIES IN THE NORTH. THIS WILL NEED TO BE WATCHED FOR INCREASING
POPS CENTRAL AND SOUTH WITH SOME POTENTIAL FOR QUICK LIGHT ACCUMS.
AS IT LOOKS NOW SOUTH WOULD BE BEST BET IN CLOSER PROXIMITY TO BAROCLINIC
ZONE AND BETTER MOISTURE. BREAK SUN NIGHT-MON WITH CANADIAN HIGH
BUILDING IN. NEXT SYSTEM FOR LATE MON NIGHT INTO TUE WHICH IS DISCUSSED
BELOW.  

EXTENDED (TUE-FRI)

LARGE MODEL DIFFERENCES WITH RESPECT TO HAPPENINGS ALONG WEST COAST.
OVERALL FAVOR BLEND OF UKMET AND GFS WHICH SUGGESTS STRONG CLOSED
LOW IN CALIFORNIA EARLY ON. MEANWHILE NORTHERN STREAM SYSTEM DIVING S/E 
CONCEPTUALLY SHOULD ACT ON EXISTING BAROCLINIC ZONE TO OUR SOUTH 
TO SPIN UP SURFACE WAVE WHICH WILL MOVE E/SE FROM NORTHERN PLAINS INTO 
OHIO VALLEY...WHICH 00Z AND 12Z UKMET SHOW. ENSEMBLES ALSO APPEAR TO SUPPORT
UKMET SOLUTION WITH CALIFORNIA CLOSED LOW AND ACTIVE NORTHERN STREAM.
THEREFORE WILL BE GOING WITH CHC SNOW LATE MON-TUE. 
NEXT WAVE IN NORTHWEST FLOW ON THANKSGIVING TO BRING CHC SNOW. TEMPS WELL 
BELOW NORMAL FOR MUCH OF THE EXTENDED WITH SOME MODERATION LATE. 
TRICK WITH TEMPS WILL BE POTENTIAL FOR SOME SNOW COVER BY MIDWEEK...WHICH 
CASE READINGS COULD BE EVEN COLDER.
  
.DVN...
IA...NONE.
IL...NONE.
MO...NONE.

MCCLURE