[LeArc] Forecast Discussion : MLI@ 8/10/02 3:15:11 PM

[learc@mailman.qth.net]

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


FXUS63 KDVN 102018
AFDMLI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
317 PM CDT SAT AUG 10 2002

SYNOPTIC PICTURE DOMINATED BY UPPER VORTEX MOVING ALONG MN/CANADIAN 
BORDER AT MIDDAY. AT SURFACE...WEAK TROUGH EXTENDED SOUTH FROM 
WESTERN WI THROUGH CENTRAL IA AND NW MO AT MIDDAY. WEAK SHOWERS 
CONTINUED ALONG SOUTHERN EDGE CLOSER TO DEEPER MOISTURE IN CENTRAL 
PLAINS...WHILE ONLY FEW MID LEVEL CLOUDS ASSOCIATED WITH TROUGH AND 
ABUNDANT CI FROM CONVECTION TO SW STREAMING OVER EASTERN IA. MOST 
IMPORTANT SYNOPTIC FEATURE FOR FORECAST IS VORTEX SEEN ON WATER 
VAPOR IMAGERY OVER NORTHERN BC AND REINFORCING 120 KT H2 JET DIVING 
SE INTO WESTERN CANADA. ALL MODELS SIMILAR IN PUSHING THIS ALONG 
SIMILAR CANADIAN BORDER PATH AS CURRENT LOW...ALTHOUGH DEEPER WITH 
STRONGER SURFACE FEATURES TO IMPACT FORECAST AREA MONDAY INTO 
TUESDAY. MAIN FORECAST CHALLENGE IS POPS SUNDAY NIGHT INTO TUESDAY.

12Z MODELS OVERDOING PRECIP ASSOCIATED WITH CURRENT SYSTEM TO THE 
NORTH...WITH ETA HAVING QPF CLOSEST TO REALITY AT 18Z NOT COVERING 
MN AND WI AND KEEPING RAIN WELL TO OUR SW. WILL FOLLOW ETA AND KEEP 
FORECAST AREA DRY TONIGHT. NOT MUCH CLOUD COVER UPSTREAM AND SHOULD 
THUS COOL BACK INTO MID TO UPPER 60S...NEAR FWC GUIDANCE. ON 
SUNDAY...FLOW BEGINS TO BACK AS INCOMING SHORTWAVE LEADS TO 
FRONTOGENESIS OVER HIGH PLAINS. MODELS TRY TO GENERATE QPF OVER 
FORECAST AREA...ESPECIALLY IN NW AS WARM AIR ADVECTION KICKS IN AT 
H85. HOWEVER...WITH LACK OF SURFACE BOUNDARIES OR UPPER FORCING... 
WILL LEAVE OUT FOR NOW DESPITE DECENT INSTABILITY IN NW BY LATE 
AFTERNOON. LOOKING AT DEGREE OF WARMING TODAY WITH CLOUD COVER... 
WARMER MET LOOKING MORE AND MORE REALISTIC WITH FEWER CLOUDS SUNDAY 
AND BUMPED UP HIGHS TO BETWEEN FWC AND MET WITH UPPER 80S TO LOWER 
90S. SUNDAY NIGHT...MAY SEE SOME TSRA IN WARM SECTOR AS H85 MOISTURE 
AND LOW LEVEL JET KICKS IN AND KEPT CHANCE POPS GOING. 

MODELS TRENDING A LITTLE SLOWER WITH FRONTAL PASSAGE LATE AFTERNOON 
AND EARLY EVENING ON MONDAY AND THUS HAVE ADJUSTED POPS. LINGERING 
BOUNDARIES FROM OVERNIGHT CONVECTION COULD AID IN FIRING STORMS 
MONDAY AFTERNOON...BUT MAIN FOCUS WILL BE FRONT ANTICIPATED FROM 
ABOUT DBQ TO IOW LINE BY 00Z. CONFINED LIKELY POPS TO E CENTRAL IA 
ZONES WITH CHANCE ELSEWHERE. MONDAY NIGHT...LOCALLY HEAVY RAINFALL 
STILL A THREAT AS FRONT PUSHES THROUGH SURFACE THETA E RIDGE WITH 
FORECAST PRECIP H20 OVER 150 PERCENT OF NORMAL AND WENT WITH LIKELY 
POPS. SHOWERS LINGER TUESDAY WITH FEW TSRA POSSIBLE IN EAST IN 
MORNING AS UPPER TROUGH PUSHED THROUGH. 

IN EXTENDED...WEDNESDAY MORNING STILL LOOKS COOL AS HIGH PUSHES IN 
FROM WEST. THIS HIGH HAS ONLY BRIEF INFLUENCE BEFORE WARM AIR 
ADVECTION KICKS IN WED AFTERNOOON. TEMPERATURES NUDGED UPWARD SOME 
IN EXTENDED...BUT OVERALL STILL BELOW GUIDANCE. KEPT TSRA CHANCES IN 
THURSDAY WITH NEXT SHORTWAVE TO NORTH AND INTRODUCED FOR SATURDAY AS 
FRONT DEPICTED TO STALL OUT JUST TO SOUTH.         

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

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