[LeArc] Forecast Discussion : MLI@ 7/3/02 1:09:31 PM

[learc@mailman.qth.net]

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


FXUS63 KDVN 031807
AFDMLI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
105 PM CDT WED JUL 3 2002

.OVERVIEW...SIGNIFICANT AND DISTINCT CHANGES UNDERWAY SUPPORTING MORE
FAVORABLE ENVIRONMENT FOR SHOWERS AND STORMS WITH SLIGHTLY COOLER
TEMPERATURES.  UPPER AIR ANALYSIS SHOWS SLIGHT COOLING ALOFT PLUS SLOW
MOVING WEAK BOUNDARY SLIDING SOUTHEAST NOW ALONG MN/IA BORDER. TWO
ADDITIONAL FACTORS ARE THE CLOSED UPPER LOW CIRCULATION THAT HAS BEEN
MOVING SLOWLY WEST FOR THE PAST THREE PLUS WEEKS IS STARTING TO GET
PULLED NORTH AND GRADUALLY PHASE WITH THE CLIMATOLOGICAL ON TIME FIRST
SIGNIFICANT PULSE OF SOUTHWEST MONSOON MOISTURE.  THESE FOUR FACTORS
WILL BE WELCOME AS WE SHOULD END OUR DRY SPELL OVER THE NEXT FEW DAYS.
UPPER AIR ANALYSIS SHOWS MUCH STRONGER JET IN CANADA ALSO TO ALLOW FRONT
TO SLIDE SOUTH.

...TIMING RETURN AND EXTENT OF SHRA/TSRA NEXT FEW DAYS CHALLENGE AND
BACKDOOR COOL FRONT NEAR TERM ISSUES...THEN MAJOR CHANGE NEXT WEEK AND
COOL DOWN MEDIUM RANGE CHALLENGE...

.DIAGNOSIS AND DAYS 1-3...MODELS VARY WIDELY HANDLING MOISTURE AND
BACKDOOR COOL FRONT NEXT 60 HOURS WITH ETA BL AND LOW LEVEL MOISTURE
SLIGHTLY TOO WARM AND DRY WHICH ARE IMPACTING POPS/QPF...SO WILL LEAN
TOWARD AVN/UKMET/NGM MIX. PERSISTENCE AND CONCEPTUAL POOLING OF MOISTURE
ALSO MORE REASONABLE AND IN LINE WITH MODEL MIX AND THUS LIMITED USE OF
ETA. THIS SUGGEST CHANCE POPS TONIGHT...MAINLY NORTH OF I-80 AS BOUNDARY
WORKS SOUTH AND THEN AT LEAST HIGH CHANCE POPS WITH HEATING BY THURSDAY
AFTERNOON EVENING...ESPECIALLY SOUTH SECTIONS.  WEAK SHEAR AND LOTS OF
MOISTURE SUPPORT SLOW MOVING STORMS FOR LOCALIZED HEAVY AMOUNTS INTO
THURSDAY EVENING...BUT WILL NOT PUT IN ZONES AS LIKELY ISOLATED AREAS
OVERALL.  LOW TEMPS TONIGHT...CLOSE TO PERSISTENCE AND THURSDAY HIGHS
WILL TREND NEAR TO BELOW NORTH AND NORTHEAST TOMORROW WITH MORE CLOUDS
AND THEN NEAR TO SLIGHTLY ABOVE SOUTH OF FRONT. BACKDOOR COOL FRONT
EFFECTS ON TEMPS BY THURSDAY NIGHT AND WILL SIDE TO COOL SIDE EAST
LOCATIONS AND NEAR TO ABOVE SW AREAS WITH HIGHER POPS THERE. FRIDAY...
REAL CHALLENGE AS EAST WINDS AND CONFLUENT FLOW SHOULD ALLOW FOR STORMS
JUST WEST OF FORECAST AREA AND QUESTION HOW MUCH CLOUDS TO AFFECT
AREA...EXPECT SOME HEAVY RAINS JUST WEST OF AREA WITH THIS PATTERN SO
NEED TO MONITOR NEXT FEW SHIFTS.  WILL FOLLOW NEAR GUIDANCE FOR NOW
WHICH ARE SLIGHTLY COOLER AND DRIER BUT COULD BE EVEN COOLER WITH CLOUDS
AND POPS.  WILL GO LOW CHANCE POPS WEST SECTIONS FRI NIGHT. THEN POPS
BACK IN LATE SATURDAY AS WARM FRONT PUSHES SLOWLY BACK TOWARD AREA.

.EXTENDED (SUN-WED)...AVN/UKMET AND LESSER EXTENT ECMWF ALL SUPPORT NEXT
FRONT TO ARRIVE LATE WEEKEND AND EARLY NEXT WEEK WITH CHANCE OF LOTS OF
STORMS AND SHOWERS AS LOTS OF MONSOON MOISTURE POOL ALONG BOUNDARY.
THEN MAJOR SHIFT TO NW FLOW TUE/WED WITH DRYING AND COOLING WITH TEMPS
NEAR MEX REASONABLE AND CHANCE MAY NEED TO DROP A CATEGORY NEXT DAY OR
SO AS STRENGTH OF UPPER HIGH AND SURFACE WITH CAA BETTER HANDLED.  WILL
MAKE FOR A BETTER CONDITIONS NEXT FOR OUTSIDE ACTIVITIES.


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

NICHOLS