[LeArc] Forecast Discussion : MLI@ 7/10/02 2:18:33 PM

[learc@mailman.qth.net]

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


FXUS63 KDVN 101916
AFDMLI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
215 PM CDT WED JUL 10 2002

OVERALL...TOUGH FORECAST WITH SMALL BUT INTENSE CLOSED UPPER LOW
SPINNING AT 18Z NEAR FARGO ND...MOVING SOUTHEAST AT 15 MPH.  SYSTEM
RESPONSIBLE FOR LARGE CONVECTIVE MCS/MCC LAST NIGHT AFFECTING IOWA INTO
MID DAY TODAY.  LOTS OF CLOUDS AND PRECIPITATION AT 18Z ALONG NORTH OF
SURFACE OCCLUSION BOUNDARY WITH OVERRUNNING RA/SHRA/TSRA AND STORMS NEAR
WARM/COLD FRONT. UPPER AIR SUPPORTS MODEL GUIDANCE FOR SYSTEM TO MOVE
INTO CENTRAL IOWA NEXT 24 TO 36 HOURS. SURFACE ANALYSIS SHOWS COMPLEX
PATTERN WITH STATIONARY FRONT ALONG I-70 INTO TRIPLE POINT NEAR MCI WITH
OCCLUSION NORTH ALONG I-35 TO LOW REFLECTING UPPER SYSTEM IN SW
MINNESOTA.  VERY COOL TEMPS IN UPPER 50S TO MID 60S IN RAIN COOLED AIR
NORTH AND EAST OF BOUNDARY...INCREASING EAST WINDS OFF LAKE MICHIGAN
SUPPORT STRONG SFC CONVERGENCE JUST SE OF PARENT LOW AND PRESSURE FALLS
FOR NEW CONVECTION THERE NEXT SEVERAL HOURS.

POPS AND HOW COOL NEXT 24 HOURS...THEN CLEARING TIMING AND ENDING
PRECIPITATION MAIN FORECAST CHALLENGE...

DIAGNOSIS AND DAYS 1-3...ALL MODELS HAVING NORMAL ISSUE OF QPF PROBLEMS
WITH STRONG CONVERGENCE SE OF PARENT LOW.  THIS SUPPORTS TRENDING TOWARD
ETA (MET GUIDANCE) FOR NEW CONVECTION LATE PM/EVENING TO MOVE SE INTO
OUR WESTERN AND CENTRAL SECTIONS TONIGHT AS STORM SYSTEM MOVES SE.  THIS
RATIONALE IN LINE WITH NOWCAST CONVECTIVE TOOLS/CONCEPTUAL DYNAMIC
MODELS TONIGHT WITH GOOD DIFFLUENCE ALOFT AND FAVORABLE LOW LEVEL
CONVERGENCE ALONG AND ESPECIALLY WEST OF THE MISSISSIPPI RIVER FOR HIGH
POPS WITH LOCALLY HEAVY RAINS POSSIBLE WITH MOISTURE...FORCING AND USING
PERSISTENCE FROM HEAVY RAINS WITH SYSTEM LAST NIGHT AND THIS MORNING.
TEMPS WILL BE A MAJOR CHALLENGE WITH AMOUNT AND LOCATION OF RAINS THE
MAIN DISCRIMINATOR FOR LOWS AND HIGHS TOMORROW.  USING 18Z SURFACE IN MN
AS BAROMETER...THIS SUPPORTS VERY COOL MAX TEMPS TOMORROW WITH STIFF
EAST WIND...CLOUDS AND LINGERING RAIN...ESPECIALLY WEST OF RIVER.  WILL
TREND NEAR TO BELOW GUIDANCE MOST AREAS EXCEPT FAR EAST WHERE SOME
FILTERED SUN TO WARM TEMPS A TAD.  THIS MEANS MANY AREAS WILL SEE HIGHS
IN THE MID TO UPPER 60S TOMORROW...MAINLY ALONG AND NORTHWEST OF A DBQ
TO CWI TO AWG AXIS. THEN CLEARING LATE TOMORROW NIGHT WITH LOWS TONIGHT
NEAR TO ABOVE GUIDANCE MOST AREAS WITH CLOUDS EXCEPT NORTHWEST AND WEST
SECTIONS TONIGHT WHERE LOTS OF RAIN TO SUPPORT COOL SIDE OF LOW
GUIDANCE. THEN...BY FRIDAY...QUIET...MILD REGIME INTO SATURDAY WITH HIGH
TEMPS UPPER 70S TO LOWERS 80S HIGHS AND DEWPOINTS RELATIVELY DRY NEAR
60...GO NEAR BLEND OF MAV/FWC/MET...NICE RESPITE FROM RECENT HOT TEMPS.

.EXTENDED (SUN-WED)...TREND TOWARD ECMWF/UKMET AND LESSER EXTENT AVNXT.
THIS MEANS RETURN TO WARM AND HUMID SUMMER CONDITIONS THROUGH MONDAY
WITH TEMPS 1-2 CATEGORIES ABOVE MEX. THEN SEASONABLY MODERATE TO
STRONG COOL FRONT ARRIVE LATE TUESDAY/WEDNESDAY FOR CHANCE POPS FOR NOW
WITH SOME COOL DOWN WEDNESDAY SLIGHTLY BELOW CURRENT MEX AS MRF FAILS TO
CAPTURE THIS FRONT IN A SATISFACTORY WAY BY KEEPING TOO FAR NORTH WHICH
CONTRADICTS CONSISTENT LARGE SCALE UPPER FORCING...JUST LIKE LAST TWO
FRONTS ON DAYS 6/7.

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

NICHOLS