[LeArc] Forecast Discussion : MLI@ 8/1/02 2:35:22 PM

[learc@mailman.qth.net]

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


FXUS63 KDVN 011936
AFDMLI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
237 PM CDT THU AUG 1 2002

PRESSURE COOKER SITUATION GOING ON ACROSS THE CWA TODAY...WITH 
DEWPOINTS IN THE MID TO UPPER 70S...AND TEMPS IN THE UPPER 80S TO 
LOW 90S.  LI ON 18Z SOUNDING IS -12...WITH A CAPE OF .  MAIN 
LIMITING FACTOR IS THE CAP APPARENT ON SOUNDING OF 18C AT 750MB.  
700MB TEMP STILL 13C...SAME AS ON 12Z SOUNDING.  WE ARE GOING TO 
HAVE TO COOK A LITTLE MORE BEFORE ANY THUNDERSTORM ACTIVITY WILL 
POP.  MAY NOT DO SO UNTIL FRONT GETS MOST OF THE WAY THROUGH CWA.  
SOME SCATTERED SHOWER ACTIVITY BEING OBSERVED BEHIND FRONT.

MAIN CONCERN THIS FORECAST INCLUDES POPS TONIGHT AND AGAIN 
SATURDAY...AND TEMPS THROUGH THE WEEKEND.

12Z MODELS APPEAR TO HAVE INITIALIZED RELATIVELY WELL...THOUGH 
AVN...ETA AND NGM HAVE OVERDONE PRECIPITATION AT 18Z.  ETA HAS A 
SURFACE LOW CENTER JUST WEST OF KCID WHICH IS NOT SHOWING ON LATEST 
SURFACE ANALYSIS...WITH AVN DEPICTION OF SURFACE PATTERN MUCH BETTER 
AT 18Z.  OTHERWISE SOLUTIONS ARE FAIRLY SIMILAR...PUSHING FRONT AS 
FAR SOUTH AS BETWEEN KUIN AND KSTL BEFORE WASHING OUT.  DIFFERENCES 
SHOW BY SATURDAY...INITIALLY DEVELOPING A NEW SURFACE WARM FRONT 
ACROSS NORTHERN MO/SOUTHERN IA.  AVN KEEPS IT SOUTH...WHILE THE ETA 
PUSHES IT NORTH TO NRN IA BY 18Z.  HAVE DECIDED TO FOLLOW THE MORE 
NORTHERLY MOVEMENT OF THE FRONT...WITH PRECIPITATION FOCUSING ON 
IT.  FOR TONIGHT...WILL HAVE TO WAIT UNTIL LAST MINUTE TO DECIDE ON 
DETAILS OF POPS AND TIMING.

TEMPS TONIGHT SHOULD NOT RADIATE OUT COMPLETELY WITH ENOUGH LEFT 
OVER CLOUDS AND A LITTLE PRECIP TO KEEP TEMPS FROM DROPPING DESPITE  
DRY AIR FLOWING INTO REGION FROM THE NORTHWEST.   BIG RANGE ACROSS 
CWA...RANGING FROM THE MID 60S NORTHWEST TO NEAR 70 SOUTHEAST.  BY 
FRIDAY...NORTHEAST FLOW... AIRMASS CHANGE...AND LINGERING CLOUD 
COVER OUGHT TO REALLY KEEP TEMPS DOWN.  WILL BE GOING WARMER THAN ON 
PREVIOUS FORECAST...RANGING FROM NEAR 80 NORTH TO MID 80S SOUTH.  
SATURDAY TEMPS ALSO A BIG QUESTION.  AS FRIDAY WILL BE WARMER THAN 
FORECAST...RETURN OF WARM AIR WILL BE STRONGER THAN PREVIOUSLY 
THOUGHT...DESPITE EASTERLY FLOW AND EXPECTED CLOUD COVER FROM THE 
VICINITY OF A FRONT AND SOME POSSIBLE CONVECTION.  WILL BE GOING 
WITH MID 80S NORTH TO NEAR 90/LOW 90S SOUTH.

EXTENDED...MON-THU
MODELS SEEM TO BE SLOWING DOWN WITH FRONTAL SYSTEM EXPECTED TO 
AFFECT EARLY PART OF WEEK...AND ARE NOW FAVORING A MORE NORTHERLY 
SOLUTION THAN BEFORE.  AS A RESULT...HAVE DRAGGED POPS INTO 
MONDAY...MAINLY IN THE MORNING.  BY TUESDAY THIS FRONT IS WELL NORTH 
OF THE CWA AND REMAINS DRY.  THIS HOLDS TRUE FOR TUESDAY ALSO.  
WEDNESDAY IS QUESTIONABLE...MAY NEED TO PUT POPS INTO WED AS MODELS 
IMPLYING A WARM FRONT DEVELOPING OVER AREA WITH INSTABILITY IN WARM 
SECTOR.  FOR NOW HAVE LEFT OUT...MAINLY BECAUSE FRONT IS MORE LIKELY 
TO BE FURTHER NORTH AND SLOWER THAN DEPICTED.

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

LRE