[LeArc] Forecast Discussion : MLI@ 9/14/02 2:27:46 PM

[learc@mailman.qth.net]

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


FXUS63 KDVN 141934
AFDMLI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
235 PM CDT SAT SEP 14 2002

FRONT PROGRESSING SLOWLY THROUGH AREA...WITH LATEST ANALYSIS SHOWING 
WIND SHIFT ONLY NOW MOVING IN TO WESTERN SECTIONS OF CWA.  VERY 
LITTLE IN THE WAY OF PRECIPITATION ACROSS IA...AND DESPITE FAIRLY 
BIG HOLES IN OVC...DO NOT SEE MUCH IN THE WAY OF CONVECTIVE 
DEVELOPMENT FOR THE EARLY EVENING HOURS.  UPPER LEVEL ANALYSIS 
INDICATING THAT AT 12Z THE MAIN TROUGH AXIS WAS OVER CENTRAL IA AT 
12Z...WHICH ACCORDING TO SATELLITE IMAGERY HAS SHIFTED TO OVER 
EASTERN IA AS OF 18Z.  CONSIDERING THE FALLS AT HIGHER LEVELS...THIS 
IS GOING TO CONTINUE THIS MOVEMENT.

MAIN CONCERNS THIS FORECAST INCLUDE ENDING OF PRECIPITATION THIS 
EVENING...TEMPS NEXT FEW DAYS...AND THEN PRECIP CHANCES AGAIN 
TUESDAY.

12Z MODELS APPEAR TO HAVE INITIALIZED FAIRLY WELL...AND WILL BE 
GOING WITH A GENERAL BLEND OF THE TWO.  SLIGHTLY FAVOR SLOWER ETA 
WITH HOW FAR SOUTH IT PUSHES THIS SYSTEM...WHICH IS FARTHER NORTH 
THAN AVN.  SYSTEM SHOULD SLOW DOWN AS IT ENCOUNTERS T.S. ACTIVITY.

TONIGHT MAIN KEY WILL BE TO WATCH RADAR PRECIPITATION 
TRENDS...THOUGH AT THIS TIME WILL FOLLOW EARLIER UPDATES LEAD AND GO 
WITH LOW POPS...WITH ONLY SPRINKLES NORTHWEST...AND SLIGHT CHANCE 
SHOWERS SOUTHEAST.  GUIDANCE HAS HIGHER POPS...BUT THEY ALSO SEEM TO 
BE PUTTING OUT TOO MUCH QPF FOR THE AFTERNOON HOURS.  AM RELUCTANT 
TO MOVE CLOUDS OUT TOO SOON TONIGHT...SO WILL SLOW THIS TIMING DOWN 
SOMEWHAT.  THIS MEANS TEMPS TONIGHT WILL HAVE TO BE RAISED FROM 
CURRENT FCST.

CLEAR/NEARLY CLEAR CONDITIONS UNDER RIDGE SUNDAY AND MONDAY TO CAUSE 
TEMPS TO HAVE HIGH DIURNAL RANGE...WHICH GOING FCST HAS A FAIRLY 
GOOD HANDLE ON.  WILL STAY FAIRLY CLOSE TO THIS.

TUESDAY BOTH AVN AND ETA SWING AN IMPULSE ACROSS THE EASTERN 
PORTIONS OF THE AREA. ETA FASTER THAN AVN...BUT BOTH RELATIVELY 
DRY...SO WILL KEEP POPS LOW...AND EVEN LOWER OVER WESTERN CWA.

EXTENDED...WED-SAT
AS PREVIOUSLY DISCUSSED...SOME FAIRLY MAJOR CHANGES HAVE OCCURRED 
SINCE YESTERDAYS RUN OF THE LONGER RANGES.  BROAD UPPER LEVEL TROUGH 
OVER THE AREA DURING THE 4 DAYS OF THE EXTENDED HAVE CHANGED IN THE 
MOVEMENT OF SHORT WAVES. ON THIS RUN...A WEAK UPR LVL WAVE EXITS ON 
WED...WITH A MORE VIGOROUS WAVE AND SURFACE LOW DUE THROUGH IN THE 
THU-FRI TIMEFRAME...LEAVING ONLY SAT DRY.  OTHER MODELS...UKMET AND 
AND ECMWF MORE PROGRESSIVE.  FOR NOW...SINCE CHANGES WERE 
ANTICIPATED...WILL TREND TOWARDS THIS NEW SCENARIO.  TEMPS IN MRF 
GUIDANCE ON THE COOL SIDE.  GOING TEMPS WEDNESDAY SIGNIFICANTLY 
WARMER...AND BASED ON WAA APPARENT ON MODELS...THIS IS REASONABLE. 
OTHERWISE BIG COOL DOWN FOR WEEKEND LOOKS GOOD.

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

LRE