[LeArc] Forecast Discussion : MLI@ 4/5/2003 4:34:36 AM

Sat, 05 Apr 2003 04:34:36 -0600

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

FXUS63 KDVN 051030
AFDMLI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
430 AM CST SAT APR 5 2003

QUIET WX IN THE IMMEDIATE SHORT TERM...THEN THINGS GET INTERESTING.
SURFACE RIDGE TO BUILD IN DURING THE DAY CLEARING THE CLOUDS AS
FLOW BECOMES MORE ANTI-CYCLONIC. THEN NEXT SYSTEM BEGINS TO MOVE IN.

TO THE POINT...HAVE RAISED A WINTER STORM WATCH FOR THE ENTIRE CWFA
FOR SUNDAY AFTERNOON THROUGH MONDAY.

THIS SYSTEM WILL BE INTERESTING. UKMET CONTINUES TREND OF OCCLUDING
OFF FIRST LOW AND DEVELOPING A NEW ONE IN THE LOWER OHIO VALLEY...
THEN HAVING THE OCCLUDED LOW MOVE TOWARD KSTL. ECMWF AND AVN NOW
STARTING TO FOLLOW THIS TREND AS WELL. SHORTWAVE RIGHT ON THE HEALS
OF THIS SYSTEM IS NEGATIVELY TILTED AND MAY INFLUENCE THE MAIN SYSTEM
(ALA FUJIWARA). CONDENSATION PRESSURE DEFICITS AND FORECAST SOUNDINGS
INDICATE PRECIPITATION TO BEGIN DURING THE AFTERNOON ON SUNDAY.
SOUNDINGS AND PARTIAL THICKNESS INDICATE A MIX OF IP/RA STARTING IN
THE SOUTH THIRD...MAYBE MIXING WITH ZR SUNDAY NIGHT BEFORE CHANGING
TO ALL SNOW. NORTHERN 2/3RDS OF CWFA TO STAY ALL SNOW. ALL MODELS
SHOWING COUPLED JETS WHICH WILL INCREASE THE AGEOSTROPHIC CIRCULATION
AND INCREASE THE ALREADY IMPRESSIVE LIFT FURTHER. STILL CONCERNED
THAT MODELS DON/T HAVE A TRUE GRASP OF THE POTENTIAL QPF OF THE
SYSTEM. COLD CONVEYOR BELT CONTINUES TO REMAIN LARGE AND DEEP WHICH
SHOULD PULL MOISTURE FURTHER TO THE NORTH AND WEST THAN WHAT MODELS
CURRENTLY SUGGEST.

SNOW TO CONTINUE MONDAY WITH HEAVY SNOW POSSIBLE IN THE MORNING AS
MOVEMENT IS NOW SLOWER AND DEFORMATION ZONE TAKES STILL OVER THE
AREA. GEM IS SLOWER YET. LIGHT SNOW STILL POSSIBLE INTO MONDAY
EVENING BUT FOR NOW WILL JUST GO WITH FLURRIES. AS FOR TOTALS...6 TO
10 LOOKS GOOD BUT WOULD NOT BE SURPRISED TO SEE 8 TO 12.

HAVE ADJUSTED TEMPERATURES DOWNWARD FOR TUE-THU PERIOD AS MODELS ARE
NOT ACCOUNTING FOR NEW SNOW. EVEN WITH APRIL SUN...6 INCHES OF SNOW
WILL KEEP TEMPERATURES DOWN AND UNDER IDEA CONDITIONS WOULD TAKE
ABOUT 3 DAYS TO MELT. RETURN WAA FLOW COULD PRODUCE MORE CLOUDS THAN
WHAT MODELS CURRENTLY THING AND FOG WOULD NOT BE OUT OF THE QUESTION
EITHER.

.DVN...WINTER STORM WATCH SUNDAY AFTERNOON THROUGH MONDAY
IA...IAZ040>042-051>054-063>068-076>078-087>089-098-099.
IL...ILZ001-002-007-009-015>018-024>026-034-035.
MO...MOZ009-010.

$$

SF