[LeArc] Forecast Discussion : MLI@ 8/4/2003 3:22:16 AM

[learc@mailman.qth.net]

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


FXUS63 KDVN 040819
AFDMLI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
319 AM CDT MON AUG 4 2003

.SYNOPSIS...
UPPER LOW SEEN CHURNING ON WATER VAPOR SOUTH OF LAKE MI AT 07Z WITH 
STRONG VORTEX THAT PRODUCED WIDESPREAD CONVECTION SUNDAY OVER AREA 
ROUNDING BASE OF TROUGH IN SOUTHERN IL. AT SURFACE...WEAK LOW WAS 
OVER IN WITH TROUGH EXTENDING WEST INTO CENTRAL MO AND HIGH PRESSURE 
RIDGE AXIS WAS NOSING SOUTH FROM MN INTO NORTHWEST IA. FOG IMAGERY 
AND METARS INDICATED FOG DEVELOPING FROM FREEPORT WEST INTO MISS 
RIVER VALLEY.

.TODAY THROUGH TUESDAY NIGHT...
IMMEDIATE CHALLENGE WILL BE MAGNITUDE AND EXTENT OF FOG EARLY THIS 
MORNING. MSAS INDICATED TEMP/DEWPOINT DEPARTURE AXIS OF 1 DEGREE OR 
LESS OVER NORTHWEST IL...TRENDING SOUTHWEST INTO FAR EASTERN IA WITH 
ANOTHER AXIS APPROACHING SATURATION OVER SOUTHWEST WI INTO NORTHEAST 
IA. THIS IS LINING UP WELL WITH AREAS THAT HAD MOST RAIN SUNDAY... 
ACCORDING TO 88D STORM TOTAL PRECIP. SOME STRATUS CREEPING SOUTH OUT 
OF WI THAT MATCHES WELL WITH META LOW LEVEL RH FIELD MAY COMPLICATE 
MATTERS AND PREVENT LOW VISIBILITIES AS IT MOVES INTO FAR NW IL 
TOWARD SUNRISE. SO FOR NOW WILL PLACE AREAS OF FOG...LOCALLY 
DENSE...IN GRIDS/ZONES AND HOLD OFF ON ANY HIGHLITES. 

THROUGH REST OF TODAY...MODELS NOW MORE CONSISTENT WITH UPPER LOW 
SHIFTING TO LOWER MI WITH ACCOMPANYING COOL POOL ALOFT SHIFTING 
EAST. NO SIGNIFICANT VORT MAXIMA SEEN ON SATELLITE IMAGERY THIS 
MORNING TO PUSH THROUGH AREA TODAY. THIS...ALONG WITH DEVELOPING CAP 
AROUND H7 WILL LIMIT CONVECTION TO ONLY ISOLATED...AND HAVE CONFINED 
POPS BACK TO EAST OF MISS RIVER FOR AFTERNOON. WENT ALONG WITH 
COOLER END OF GUIDANCE HIGHS FROM UPPER 70S NORTH TO LOWER 80S 
SOUTH. TONIGHT...SHORTWAVE TOPPING WESTERN RIDGE MOVES INTO 
NORTHWEST MN WITH ELEVATED WARM FRONT APPROACHING FAR NORTHEAST MO 
AND SOUTHEAST IA ZONES AND THUS LIMITED LOW LATE NIGHT POPS TO THOSE 
AREAS. MODELS HAVE POOR AGREEMENT ON LOCATION AND TIMING OF THIS AND 
ANOTHER VORT MAX THAT FOLLOWS TUESDAY NIGHT IN NW FLOW. FOR 
NOW...TRENDED MOST CLOSELY WITH GFS GUIDANCE KEEPING ISOLATED TO 
SCATTERED POPS FOR MAINLY NORTHWEST HALF OF CWA...HITTING TUESDAY 
MORNING AND LATE TUESDAY NIGHT HARDEST. FOR TEMPERATURES...STAYED ON 
COOL END OF GUIDANCE.   
...SHEETS

.WEDNESDAY THROUGH FRIDAY...
MODELS FINALLY BEGINNING TO SHOW SOME AGREEMENT ON THE VORT MAXES 
THAT MOVE THROUGH THE NORTHWEST FLOW WEDNESDAY...WITH A SLOWER 
HANDLING OF THE VORT MAX THAN THE 12Z MODEL RUNS.  HATE TO APPEAR TO 
FLIP FLOP...BUT HAVE DECIDED TO ADD PRECIP BACK INTO WEDNESDAY AFTER 
COORDINATING WITH SURROUNDING OFFICES.  FOR THE REMAINDER OF THE 
WEEK...UPPER LEVELS REMAIN NEARLY THE SAME...WITH THE UPPER LEVEL 
LOW STILL OFF TO THE EAST...AND LONGWAVE RIDGE OVER THE HIGH 
PLAINS...WITH NORTHWEST FLOW OVER THE MIDWEST.  SURFACE RIDGING 
BUILDS IN OVER THE CWA FOR THURSDAY AND FRIDAY...SO BOTH DAYS SHOULD 
BE DRY.  

.SATURDAY AND SUNDAY...A FRESH SURFACE LOW DEVELOPS OVER WESTERN 
NEBRASKA/KANSAS IN RESPONSE TO A FAIRLY STRONG VORT MAX THAT MOVES 
THROUGH THE UPPER LEVEL RIDGE.  NEW MRF SLOWING THIS DOWN FROM 
PREVIOUS RUN...SO HAVE PULLED SATURDAY PRECIP OUT OF FCST...THOUGH 
SUNDAY STILL LOOKING REASONABLE.
...LE

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

$$