[LeArc] Forecast Discussion : MLI@ 4/20/2003 3:35:35 AM

[learc@mailman.qth.net]

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


FXUS63 KDVN 200832
AFDMLI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
332 AM CDT SUN APR 20 2003

UPPER LOW AND LARGE COMMA CLOUD DOMINATES NORTH CENTRAL PART OF 
COUNTRY EARLY THIS MORNING. LOW WAS CENTERED IN NORTHEAST SD 
VICINITY WITH TROUGH EXTENDING SOUTH INTO CENTRAL OK. WIDESPREAD 
CONVECTION OCCURRING AHEAD OF MAIN TROUGH FEEDING ON 50 KT LOW LEVEL 
JET AND H85 THETA E RIDGE AXIS FROM EAST TX INTO WI. AT 07Z MAIN 
SURFACE LOW WAS CENTERED OVER W CENTRAL WI WITH COLD FRONT SOUTH 
ACROSS EASTERN IA TO SOUTHEAST OK. CONVECTION IN MY CENTRAL AND 
EASTERN CWA RAPIDLY DECREASING EARLY THIS MORNING AND SHIFTING EAST 
AS MAIN MID LEVEL VORT OVER N CENTRAL MO PUSHES EAST ALONG WITH 
THETA E RIDGE PUSHING EAST AHEAD OF COLD FRONT. MAIN FORECAST 
CHALLENGE IS LIGHT PRECIP CHANCES NEXT 36 HOURS AND TEMPERATURES.

ALL MODELS NOW IN CLOSE AGREEMENT WITH MOVEMENT OF MID LEVEL VORTEX 
AND LOW LEVEL CYCLONE PUSHING EAST-NE INTO GREAT LAKES. GFS HAD 
OVERALL BEST PLACEMENT OF SURFACE FEATURES AT 06Z...BUT ALL SHOW 
SAME GENERAL IDEA AND BLEND SOLUTION FOLLOWED THROUGH SHORT TERM. 

88DS SHOW SHOWERS MAINLY PREFRONTAL FROM MISS RIVER EASTWARD EARLY 
THIS MORNING WITH EXCEPTION OF SMALL AREA OF CONVECTION OVER SOUTH 
CENTRAL IA ASSOCIATED WITH MID LEVEL VORT ENERGY PROGGED BY RUC AND 
06Z META TO MOVE NORTHEAST WITH FEATURE ACROSS EASTERN IA THIS 
MORNING. WILL THUS KEEP SCATTERED SHOWERS THROUGH MID MORNING...BUT 
REMOVE MENTION OF THUNDER. ANOTHER ROUND OF SHOWERS EXPECTED THIS 
AFTERNOON INTO EVENING AS MID LEVEL VORTICITY LOBE CURRENTLY 
ROTATING THROUGH WESTERN DAKOTAS ROTATES THROUGH. LOW LEVEL 
CONVERGENCE IN CYCLONIC FLOW WILL BE THERE...BUT Q-G FORCING NOT 
IMPRESSIVE AND MOISTURE LIMITED...SO KEPT ONLY SCATTERED POPS GOING. 
LOW CLOUDS WILL LINGER WITH COLD ADVECTION FROM SURFACE THROUGH H85 
TO PREVENT MUCH TEMPERATURE RISE. GUIDANCE LOOKED TO WARM AND 
SLIGHTLY UNDERCUT MAV HIGHS. TONIGHT...DEEP CYCLONIC FLOW REMAINS 
WITH FORECAST SOUNDINGS SHOWING SHALLOW LOW LEVEL MOISTURE LAYER 
WITH DRY MID TO UPPER LAYERS DEVELOPING TO SUPPORT NO MORE THAN 
DRIZZLE. KEPT CLOUDS OVER AREA THROUGH MOST OF MONDAY UNTIL LOW 
LEVEL MOISTURE AND CYCLONIC FLOW SHIFTS EAST LATE AFTERNOON. THIS 
WILL LIMIT HIGHS TO 50S AND STAYED ON LOW END OF GUIDANCE. SURFACE 
RIDGE OVER CENTRAL IA...CLEAR SKIES WITH DEEP DRY LAYER...AND MOIST 
GROUND MAY SET STAGE FOR FOG TUESDAY MORNING AND INTRODUCED PATCHY 
FOG IN GRIDS AND ZONES. WENT CLOSEST TO COOLEST FWC GUIDANCE WITH 
LOW TO MID 30S. 

NO SIGNIFICANT CHANGES TO DAYS 3 THROUGH 7 WITH RIDGING AT SURFACE 
AND ALOFT EARLY TO MID WEEK...THEN OVERRUNNING PATTERN LATE THURSDAY 
AS LOW EMERGES FROM ROCKIES INTO HIGH PLAINS. GFS SHOWING TYPICAL 
BIAS AS OF LATE DEVELOPING QPF INTO AREA TOO SOON...AS EARLY AS 
WEDNESDAY NIGHT. STAYED THE COURSE WITH GOING FORECAST OF SHOWERS 
DEVELOPING THURSDAY AFTERNOON CONTINUING INTO FRIDAY. LITTLE CHANGES 
TO TEMPERATURES IN EXTENDED GRIDS. 

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

$$

SHEETS