[LeArc] Forecast Discussion : MLI@ 8/3/2003 3:37:41 AM

[learc@mailman.qth.net]

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


FXUS63 KDVN 030834
AFDMLI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
335 AM CDT SUN AUG 3 2003

PERSISTENCE TYPE FORECAST FOR ONE MORE DAY AS STACKED DEEP 
CIRCULATION OVER LAKE SUPERIOR CONTINUES TO DOMINATE AREA. 
DIFFERENCE TODAY WILL BE GRADUAL WEAKENING AND SOUTHWARD MOVEMENT OF 
VORTEX AS BLOCKING PATTERN BEGINS TO BREAK DOWN OVER SOUTH CENTRAL 
CANADA. THIS WILL RESULT IN MORE WIDESPREAD DIURNAL CONVECTION 
ESPECIALLY OVER NORTHEAST HALF OF CWA THAN PAST FEW DAYS. 

WATER VAPOR IMAGERY SHOWS ONE WEAK SHORTWAVE OVER SOUTHERN MN AND 
SECOND STRONGER VORT MAX MOVING INTO NORTHERN MN. TIMING OF LEAD 
WAVE PUSHES IT ACROSS MISS RIVER LATE THIS MORNING...THEN SECOND 
STRONGER VORT MAX SHOWN BY SHORT TERM MODELS TO REACH NORTHEAST IA 
AND FAR NORTHWEST IL LATE AFTERNOON. WITH THIS LATTER WAVE ARRIVING 
DURING FAVORABLE DIURNAL INSTABILITY MAX...HAVE RAISED THUNDERSTORM 
POPS TO 40 PERCENT OVER NORTHEAST IA AND 50 PERCENT OVER FAR NW 
IL...WHERE LOW LEVEL MOISTURE AND BOUNDARIES EXPECTED TO BE MORE 
ABUNDANT. WILL THEN SEE IDEAL CONDITIONS FOR LATE NIGHT/EARLY 
MORNING FOG AFTER CONVECTION EXITS AND LOW LEVEL MOISTURE 
LINGERS...MUCH LIKE CONDITIONS EARLY THIS MORNING OVER NORTHERN MN 
AND WI. 

MONDAY AND MONDAY NIGHT...CONSIDERABLE DIFFERENCES APPEAR IN MODEL 
HANDLING OF UPPER LEVEL LOW AND SURFACE FEATURES. LEANED MORE 
CLOSELY TOWARD GFS AND UKMET SOLUTION WITH MORE NORTHERLY TRACK OF 
UPPER LOW AND FASTER MOVEMENT OF FEATURE NORTHEAST BACK INTO ONTARIO 
BY TUESDAY MORNING. THIS WOULD RESULT IN MORE ANTICYCLONIC FLOW 
DEVELOPING OVER AREA AS OPPOSED TO ETA THAT WOULD KEEP LOW OVER 
LOWER MI AND PLACE ESPECIALLY NORTHWEST IL IN DEEP CYCLONIC FLOW. 
WITH SOME UNCERTAINTY...KEPT LOW SCATTERED POPS GOING FOR AFTERNOON 
THUNDERSTORMS IN FAR EAST...THEN BUFFER ZONE OF SLIGHT CHANCE INTO 
EASTERN IA. MORE PROGESSIVE GFS THEN BRINGS IN RETURN FLOW AND 
ELEVATED WARM ADVECTION TYPE CONVECTION LATE MONDAY NIGHT. 
INTRODUCED SLIGHT CHANCE LATE NIGHT POPS TO GRIDS TO COORDINATE WITH 
DMX SCATTERED POPS. ...SHEETS

TUESDAY AND WEDNESDAY...A NICE LITTLE SHORT WAVE DROPS SOUTHEAST 
THROUGH THE UPPER LEVEL FLOW TUESDAY AND WEDNESDAY...MAINLY 
AFFECTING THE CWA DURING THE TUESDAY NIGHT AND EARLY WED TIME 
FRAME.  MODELS SHOWED THE WAVE ON THE LAST 3 RUNS...BUT ARE HAVING 
TROUBLE PINNING DOWN THE TIMING.  HAVE DECIDED TO THROW IN A LOW POP 
FOR TUESDAY NIGHT AND WEDNESDAY MORNING...AND WILL HAVE TO CONTINUE 
TO REFINE AS THIS GETS A LITTLE CLOSER.  

WEDNESDAY THROUGH SATURDAY...THE UPPER LEVEL FLOW BECOMES VERY 
AMPLIFIED AS THE UPPER LEVEL LOW FINALLY PULLS OFF TO THE EAST.  
SURFACE RIDGING FINALLY SETTLES IN OVER THE AREA AND THE UPPER RIDGE 
SHIFTS EAST TO THE HIGH PLAINS FOR THE THURSDAY THROUGH SATURDAY 
TIME FRAME.  HAVE GONE WITH A GRADUAL WARMING TREND THROUGH THIS 
PERIOD WITH DRY CONDITIONS...THOUGH CORN WILL KEEP DEWPOINTS FROM 
GETTING MUCH BELOW 60. ...LE

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

$$