[LeArc] Forecast Discussion : MLI@ 1/15/03 2:14:56 AM

[learc@mailman.qth.net]

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


FXUS63 KDVN 150825
AFDMLI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
220 AM CST WED JAN 15 2003

.OVERVIEW...WEST COAST SYSTEM NOW ONSHORE WITH DOUBLE VORT CENTERS
ONE OVER N CA AND ANOTHER IN BRITISH COLUMBIA.  SATELLITE SUPPORTS
THIS WITH LEADING EDGE OF HIGH CLOUDS NOW INTO WESTERN IOWA.  850
ANALYSIS SHOWS GOOD FRONTAL CONVERGENCE IN PLAINS AHEAD OF SYSTEM
WHICH LATEST RADAR TRENDS SUPPORT.  UPPER AIR SHOWS STRONG JET
BISECTING AREA WITH WEST COAST SYSTEM TO SLIDE EAST SOUTHEAST DUE TO
UPSTREAM ENERGY LIMITING ANY NORTHWARD PROGRESSION PER HEIGHT FALL
PATTERN AND NO HEIGHT RISES AHEAD WESTERN SYSTEM.  THIS SUGGEST SNOW
SOUTH 1/3 AREA...POSSIBLY UP TO I-80 CORRIDOR FOR PRECIPITATION.

...SNOW AMOUNTS AND TIMING WITH NORTH EXTENT WITH DECISION FOR
ADVISORY MAIN FORECAST ISSUE...

.DIAGNOSIS AND DAY 1-3...ETA HANDLES 850 WARM FRONT BEST WHICH IT
SHOULD...THOUGH QPF AMOUNTS OVERDONE AT 06Z ALONG FRONT.  06Z DATA
SUGGESTS USING ETA/GFS FORCING WITH UKMET ALSO SIMILAR.   THUS...WITH
850 TEMPS OF -10C OR COLDER AND USING NORMAL 20 TO 25 TO 1 RATIO FOR
THESE TEMPS AND SUPPORTED BY 20 TO 25 TO 1 RATIOS OBTAINED FROM LAST
NIGHT'S EVENT...LEADS TO 3-6 INCH AMOUNTS ALONG AND SOUTH OF HIGHWAY
34.  SO WILL GO WITH ADVISORY THERE SINCE SNOWS EXPECTED TO START
NEAR TO JUST AFTER SUNSET WEST SECTIONS AND NOT HAVING ANY WATCH OUT
TO GET WORD OUT. MOST AREAS SOUTH SHOULD SEE MORE SIGNIFICANT SNOW TO
BE TOWARD TO AFTER MIDNIGHT.  TEMPS ARE WELL BELOW FREEZING...THIS
WILL MINIMIZE ANY MELTING TO AID IN ACCUMULATIONS. THEN A NARROW
STRIP OF COUNTIES JUST SOUTH OF I-80 IN IOWA...AND ALONG I-80 IN
ILLINOIS FOR 1 TO 2 INCHES POSSIBLE.  EXPECT FLURRIES AND CHANCE
SNOW FAR NORTH AREAS WITH UPPER TROUGH.  TRY AND INCORPORATE SNOW
COVER THEN IN SOUTH AREAS AFTER THURSDAY FOR LOWER TEMPS THERE AS
ARCTIC AIR FEEDS IN THROUGH FRIDAY.

.EXTENDED (SAT-WED)...NW FLOW CONTINUES WITH NEXT SHORT WAVE
SUPPORTING DECENT CHANCE SNOW SATURDAY...BUT AGAIN LIMITED AMOUNTS
DUE TO STARVED MOISTURE.   PLAN LITTLE ADDITIONAL CHANGES THOUGH
APPEARS STRONGEST SURGE OF ARCTIC AIR OF SEASON TO MOVE IN EARLY NEXT
WEEK.

COORDINATED WITH...DMX...LSX...EAX...LOT...ILX...THANKS.

.DVN...
IA...WINTER WEATHER ADVISORY TONIGHT AND THURSDAY ALONG AND SOUTH OF
HIGHWAY 34.
IL...WINTER WEATHER ADVISORY TONIGHT AND THURSDAY ALONG AND SOUTH OF
HIGHWAY 34.
MO...WINTER WEATHER ADVISORY TONIGHT AND THURSDAY.

NICHOLS