[LeArc] Forecast Discussion : MLI@ 9/23/02 2:13:41 AM

[learc@mailman.qth.net]

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


FXUS63 KDVN 230719
AFDMLI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
220 AM CDT MON SEP 23 2002

ANOTHER 120 KT JET DIVING INTO BASE OF LONGWAVE NORTH AMERICAN 
TROUGH PUSHING CLIPPER LOW INTO DAKOTAS AT 06Z. THIS WILL SWEEP 
ANOTHER COLD FRONT THROUGH FORECAST AREA AS THE LOW PASSES TO NORTH 
THIS AFTERNOON. WITH DRY AIRMASS AND BEST LIFT TO NORTH...DO NOT 
EXPECT ANY RAIN. MAIN FORECAST CHALLENGE IS WARMUP TODAY ON SW PRE 
FRONTAL FLOW AND THEN HOW COLD TEMPERATURES WILL DROP TONIGHT AS 
SURFACE HIGH PRESSURE REBUILDS OVER AREA.

SURFACE LOW AT 06Z WAS IN DAKOTAS JUST NORTH OF KABR...CLOSEST TO 
AVN 6HR FORECAST POSITION WITH 3 HR PRESSURE FALL AXIS POINTING MORE 
TOWARD ETA/S SLIGHTLY MORE SOUTHERLY LOW TRACK. AT UPPER LEVELS AVN 
CONTINUES SEVERAL RUN TREND BEING ODD MODEL OUT WITH MORE VIGOROUS 
REFLECTION OF SHORTWAVE AT H5 AS IT MOVES ACROSS NRN WI TODAY AND 
ONLY MODEL WITH LIGHT QPF INTO NORTHERN CWA. GENERALLY FOLLOWED ETA 
WITH FRONT SWINGING THROUGH BETWEEN 18Z AND 00Z TODAY ACCOMPANIED BY 
ONLY BROKEN MID LEVEL CLOUDS. WILL AGAIN BE BREEZY...ESPECIALLY 
NORTH. SCT-BKN MID LEVEL DECK MOVING INTO NW IA REACHING EASTERN IA 
THIS MORNING AND WITH EARLY AFTERNOON FRONTAL PASSAGE WILL KEEP NW 
ZONES COOLEST WITH UPPER 60S...ELSEWHERE WILL GO CLOSE TO MET 
GUIDANCE WITH 70 TO LOWER 70S.

SURFACE HIGH OVER SE ALBERTA SETTLES INTO NORTHERN MO BY 12Z TUESDAY 
WITH VERY DRY AIR ALOFT CREATING IDEAL CONDITIONS FOR RADIATIONAL 
COOLING AND POSSIBLY FIRST FROST. GUIDANCE TEMPERATURES FROM 00Z 
CYCLE A BIT COOLER THAN PREVIOUS RUN AND TRENDING CLOSER TO DAYSHIFT 
NUMBERS AND WILL CONTINUE WITH 30S OVER ENTIRE CWA AND FROST 
WORDING. WILL LEAVE POTENTIAL FOR ADVISORY TO DAYSHIFT. SURFACE HIGH 
MOVES SLOWLY ACROSS AREA TUESDAY WITH ONLY WEAK RETURN FLOW TOWARD 
EVENING IN WEST. AFTER COLD START...LOWER END OF GUIDANCE TEMPS 
FAVORED WITH 60 NORTH TO MID 60S SOUTH. STRONG WARM AIR ADVECTION AT 
H85 DEVELOPS TUE NIGHT INTO WED AHEAD OF NEXT WAVE MOVING INTO 
NORTHERN ROCKIES. WILL STAY AT LEAST ONE CATEGORY ABOVE GUIDANCE 
WITH MID TO UPPER 70S OVER ALL BUT FAR NORTH. 

IN EXTENDED...NEXT STRONG SHORTWAVE PASSES THROUGH THURSDAY OR 
FRIDAY...DEPENDING ON MODEL WITH REMNANTS OF ISIDORE MOVING INTO 
LOWER MISS OR OHIO VALLEY POSSIBLY HAVING SOME IMPACT. 00Z AVN 
SIMILAR TO CANADIAN AND UK WITH BEST RAIN CHANCES THURSDAY INTO 
EARLY FRIDAY. LATEST UK BRINGS ANOTHER STRONG WAVE THROUGH ON 
SATURDAY...BUT NOT ENOUGH MODEL CONSISTENCY OR CONFIDENCE TO CHANGE 
DRY WEEKEND. WILL CONTINUE WITH WELL BELOW NORMAL TEMPERATURES WITH 
LOWS ESPECIALLY UNDERCUTTING GUIDANCE. 

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

DLS