[LeArc] Forecast Discussion : MLI@ 8/20/02 2:26:08 AM

[learc@mailman.qth.net]

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


FXUS63 KDVN 200729
AFDMLI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
228 AM CDT TUE AUG 20 2002

SURFACE RIDGE OVER WISCONSIN TO SHIFT EAST TOWARDS PRESSURE RISES IN 
MI OVERNIGHT.  SURFACE NEARLY STATIONARY FRONT EXTENDING FROM NEAR 
KMCI TO JUST NORTH OF KSTL.  TSTMS HAVE FIRED ALL ALONG AND JUST 
NORTH OF THE FRONT.  CIRRUS DEBRIS FROM THIS CONVECTION HAS SPREAD 
OVER SOUTHERN PORTIONS OF CWA.  DEWPOINTS ACROSS CWA HIGHEST ACROSS 
EAST AND SOUTH...AND COMBINED WITH LOW WIND SPEEDS...EXPECT 
WIDESPREAD FOG DEVELOPMENT ACROSS EASTERN HALF OF CWA...AND MORE 
PATCHY FOG OVER WEST.  CIRRUS OVER SOUTH MAY LIMIT THIS DEVELOPMENT.

00Z MODELS SEEM TO HAVE INTITIALIZED RELATIVELY WELL...THOUGH BY 06Z 
AVN HAS BEST HANDLE ON SURFACE FEATURES...POSITION OF SURFACE 
HIGH...AND CURRENT CONVECTION TRENDS.  NGM NOT TOO FAR 
BEHIND...THOUGH SURFACE HIGH TOO FAR SOUTH.  ETA OUT TO LUNCH...WITH 
NOT ONLY SURFACE HIGH TOO FAR SOUTH...CONVECTION TOO FAR NORTH...AND 
SOME OTHER DISCONTINUITYS THAT LOOK FISHY.  AM GENERALLY USING THE 
AVN...BLENDING IN THE NGM WHERE IT SEEMS APPROPRIATE.

TODAY...ANOTHER MOSTLY SUNNY DAY...WITH TEMPS SLIGHTLY WARMER THAN 
MONDAYS HIGHS.  SOUTHEAST FLOW BEGINS TO INCREASE IN RESPONSE TO 
DEVELOPING LOW OVER HIGH PLAINS...AND WARM FRONT DEVELOPS OVER 
SOUTHERN SOUTH DAKOTA AND IA/MN BORDER.  CLOUD COVER SRN CWA SHOULD 
KEEP TEMPS DOWN THERE...THOUGH NORTH AND CENTRAL SHOULD GET LOTS OF 
SUNSHINE.

TONIGHT...MCS SHOULD DEVELOP IN SERN SOUTH DAKOTA...AND MOVE 
GENERALLY EAST SOUTHEAST.  WILL NEED CHANCE POPS IN THE NORTHERN 
THIRD OF CWA...WITH DRY OR SLIGHT CHANCE TO SOUTH.  WITH WARM FRONT 
TO NORTH OF CWA...AND EXPECTED DEBRIS CLOUDS...TEMPS OUGHT TO STAY 
UP...SO WILL BE GOING WITH WARMER MAV/FWC GUIDANCE TEMPS.  

WEDNESDAY...HAD ORIGINALLY PUT POPS INTO THIS PERIOD AS IT WAS 
THOUGH THAT THE OVERNIGHT MCS WOULD DRAG OVER INTO THE MORNING.  
HOWEVER...IT SEEMS THAT THE OVERNIGHT MCS WILL ALSO LAY DOWN SOME 
OUTFLOW BOUNDARIES...AND WILL NOT BE SURPRISED AT ALL TO SEE 
CONVECTION IN THE LATE AFTERNOON ALSO.  WILL KEEP POPS IN THE LOW 
CHANCE CATEGORY.  STAYING CLOSE TO MAV TEMPS.

WEDNESDAY NIGHT...WILL HAVE TO ADD IN PRECIPITATION AS SURFACE FRONT 
SAGS SOUTH OVER CWA. THIS IS A RELATIVELY NEW DEVELOPMENT...WITH 
SOME EARLIER RUNS KEEPING FRONT TO NORTH.  HOWEVER...WITH AVN DOING 
IT FOR TWO RUNS IN A ROW NOW...AND NGM AND UKMET ALSO DOING 
SO...CANNOT IN GOOD CONCIENCE LEAVE POPS OUT.  CHANCE POPS WILL DO 
IT.

THURSDAY...WITH FRONT STILL DRAPED ACROSS AREA...ITS GOING TO BE 
DIFFICULT TO KEEP TSTMS FROM FIRING. WILL PUT LOW CHANCE SOUTH ALONG 
FRONT...AND SLIGHT CHANCE ELSEWHERE.  

EXTENDED...FRI-MON
JUST TOOK A QUICK LOOK.  THURSDAY NIGHT AND FRIDAY CHANCES OF 
THUNDERSTORMS LOOK ON TRACK...THOUGH THIS MAY NEED TO BE LINGERED 
OVER INTO SATURDAY IF THE MODEL TRENDS OF BEING TOO FAST WITH FROPA 
CONTINUE.  CURRENTLY SATURDAY IS DRY...WILL LEAVE ALONE FOR NOW.  
SUNDAYS DRY FCST LOOKS GOOD....WITH RIDGE SFC AND ALOFT.  HAVE SOME 
CONCERNS ABOUT MONDAY...WITH AN UPPER LEVEL SHORT WAVE TO MOVE 
ACROSS CWA.  WILL INCREASE CLOUDS...BUT OTHERWISE LEAVE DRY FOR NOW.

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

LRE