[LeArc] Forecast Discussion : MLI@ 11/9/02 2:22:22 AM

[learc@mailman.qth.net]

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


FXUS63 KDVN 090833
AFDMLI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
233 AM CST SAT NOV 9 2002

FAST QUASI-ZONAL FLOW UPPER LEVEL FLOW CONTINUES OVER REGION WITH 
ONE SIGNIFICANT MID LEVEL VORT THAT MOVED THROUGH LATE FRIDAY 
CURRENTLY MOVING ACROSS LOWER MI. NEXT UPSTREAM SHORTWAVE OVER 
ROCKIES AT 06Z WILL IMPACT LATER TODAY AND BE OF MORE CONSIQUENCE AS 
IT WILL HAVE HELP FROM 150 KT JET MOVING INTO NW NV. SHORT TERM 
FORECAST CHALLENGE IS HOW WARM TO GO WITH MAX TEMPERATURES AND THEN 
PRECIPITATION CHANCES LATE AFTERNOON INTO EVENING AS FORCING 
ARRIVES.

00Z GUIDANCE HAS COME TO MORE OF AN AGREEMENT THAN PREVIOUS RUNS 
WITH FEATURES THROUGH ABOUT 48 HOURS AND NO SIGNIFICANT 
INITIALIZATION PROBLEMS NOTED. STRONG WESTERN CONUS JET DIGS 
NORTHERN ROCKIES SHORTWAVE INTO MORE SIGNIFICANT TROUGH OVER N 
CENTRAL CONUS BY SUNDAY. AT SURFACE...LOW OVER NORTHEAST MT MOVES 
EAST ALONG US/CAN BORDER WITH CURRENT LEE TROUGH PUSHING THROUGH 
THIS EVENING. AVN/GFS TAKES SURFACE LOW ON A MORE SOUTHERLY PATH BY 
TONIGHT...MOVING IT INTO NORTHERN LAKE MI TONIGHT...WHILE ETA AND 
NGM KEEP MAINLY LOW OVER LAKE SUPERIOR. THE ETA/NGM SOLUTION LOOKS 
MORE REALISTIC LOOKING AT WHERE THE H85 BAROCLINIC AXIS LAYED OUT AT 
00Z. HAVE LEANED TOWARD ETA SOLUTION WITH FINER RESOLUTION IN SHORT 
TERM...THEN GFS BEYOND FOR TIMING OF COLD FRONT THAT FOLLOWS 
SUNDAY.     

LOOKING AT TODAY/S HIGHS...00Z KDVN SOUNDING SHOWS MIXING FRIDAY 
REACHED ABOVE H85. WITH WARM AIR ADVECTION AT H85 TODAY...WITH TEMPS 
PROGGED TO AS HIGH AS 12 TO 14 C BY ETA LOOKING POSSIBLE...COULD 
REACH WELL INTO 70S WTIH DEEP MIXING...AND MET GUIDANCE REFLECTS 
THIS. HOWEVER...EXPECT TEMPERATURES TO START OUT LOWER THIS MORNING 
DUE TO CLEARING CI IN WESTERN IA DUE TO STRONG NVA BETWEEN 
SHORTWAVES THAT WILL ALLOW FURTHER DECOUPLING AND RADIATIONAL 
COOLING. OTHER NEGATIVE FACTOR WILL BE HIGHER SURFACE DEWPOINTS IN 
LOWER 50S OVER CENTRAL MO ADVECTING INTO CWA TODAY TO HINDER WARM 
UP. THUS WILL COMPROMISE CLOSER TO COOLER MAV HIGHS AND GO WITH 
RANGE OF MID TO UPPER 60S. 

DIVERGENCE FROM LEFT EXIT REGION WELL AHEAD OF MAIN UPPER JET AND 
SIGNIFICANT H5-H7 Q-VECTOR CONVERGENCE DEVELOPS OVER REGION LATE 
THIS AFTERNOON INTO EVENING. AMOUNT OF AVAILABLE MOISTURE FOR 
PRECIPITATION IN QUESTION...HOWEVER. MODEL PRECIPITABLE WATER SHOWN 
TO INCREASE TO ABOVE 1 INCH BY 00Z WITH H85 DEWPOINTS AS HIGH AS 8 
OR 9 DEG C OVER SOUTHEAST HALF CWA...WHICH IS QUESTIONABLE 
CONSIDERING LOW LEVEL TRAJECTORIES. THINKING GULF MOISTURE COULD 
MAKE IT AS CLOSE AS CENTRAL IL WITH MY CWA ON NW EDGE. STEEP MID 
LEVEL LAPSE RATES AND ETA SURFACE LI/S PROGGED AS LOW AS -2 IN EAST 
SUGGEST ENOUGH INSTABILITY WILL BE IN PLACE FOR FEW THUNDERSTORMS 
AND WILL INTRODUCE WORDING FOR ALL BUT FAR NW. WILL INTRODUCE LATE 
AFTERNOON LOW SCATTERED POPS AND RAISE EVENING UP TO 40 PERCENT WEST 
AND 50 PERCENT EAST. FOR SUNDAY...WILL CUT POPS BACK TO ISOLATED 
OVER NORTH AS COLD FRONT PUSHES THROUGH EARLY WITH COLD AIR 
ADVECTION FOLLOWING WITH DOWNWARD VERTICAL MOTION. KEPT LOW POPS FOR 
SUNDAY NIGHT AS MID LEVEL SHORTWAVE AND CYCLONIC SURFACE FLOW MAY BE 
ABLE TO SQUEEZE OUT SOME LIGHT PRECIPITATION WITH THERMAL PROFILES 
FAVORING LIGHT SNOW OR FLURRIES.

NO SIGNIFICANT CHANGES TO DAYS 4 THROUGH 7. MEDIUM RANGE GUIDANCE  
CONTINUES TO SHOW PROGRESSIVE PATTERN WITH RISING HEIGHTS AND 
SURFACE RIDGING EARLY...THEN MORE ZONAL FLOW EVOLVING INTO LONG WAVE 
TROUGH TOWARD WEEKS END.  

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

DLS