[LeArc] Forecast Discussion : MLI@ 9/21/02 1:55:06 PM

[learc@mailman.qth.net]

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


FXUS63 KDVN 211902
AFDMLI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
200 PM CDT SAT SEP 21 2002

.OVERVIEW...FAST AND DYNAMIC PATTERN IN PLACE WITH 130+ KT JET DIGGING
INTO CENTRAL US.  THIS DEVELOPING DISTURBANCE CREATING NICE BAROCLINIC
LEAF ACROSS CENTRAL PLAINS INTO NW IOWA AS IT DIGS SE.  SURFACE
BOUNDARY WITH WEAK DEVELOPING WAVE NEAR KMCI EXTENDS AT 18Z FROM NEAR
KCHI TO KMCI TO KAMA.  PROFILERS AND 3 HR PRESSURE FALLS SUPPORT
BAROCLINIC GENERATION NEXT SEVERAL HOURS OVER SOUTHERN IOWA.  VIGOROUS
SYSTEM PART OF A VERY STRONG UPPER LOW VORTEX NOW TAKING SHAPE OVER
CENTRAL CANADA WITH 300+ METER HEIGHT FALLS.  ISIDORE NOW A CATEGORY 3
HURRICANE IN SOUTHERN GULF THAT COULD HAVE IMPACTS LATE WEEK DEPENDING
ON TRACK.

...POPS TONIGHT WITH DISTURBANCE AND THEN COOL DOWN SUNDAY AND THEN
POTENTIAL NEXT WAVE MID WEEK WITH ISIDORE A POTENTIAL WILD CARD
DEPENDING ON PHASING THE FORECAST ISSUES TODAY...

.DIAGNOSIS AND DAYS 1-3...ETA BEST OVERALL ON DYNAMICS AND MOISTURE AND
SINCE THIS IS A STRONG SYSTEM THIS SHOULD BE IDEAL FOR ETA SO WILL USE
TONIGHT EXCEPT FOR TEMPS BIASES AS NORMAL...THEN BLEND TOWARD
AVN/UKMET/ETA BY MONDAY. THIS SUPPORTS STRONG UVV THIS EVENING AS VORT
MAX PHASES INTO AREA WITH 10-15 MICRO-BAR PER SEC MOTION.  THIS WILL BE
ENOUGH TO WARRANT CATEGORICAL POPS CENTRAL AND SE SECTIONS DESPITE
LIMITED MOISTURE AND CHANCE POPS NW AREAS WITH A STRIP OF LIKELY POPS AS
BUFFER. DESPITE STRONG FORCING...STABLE THERMAL PROFILE DOESN/T SUPPORT
CONVECTION WITH AT BEST MAYBE A RUMBLE OR TWO OF THUNDER...NOT ENOUGH TO
CONSIDER IN ZONES. RAIN SHOULD LAST NO LONGER THAN A COUPLE OF HOURS AS
850 FRONT CRASHES THROUGH. THIS FAST SYSTEM SHOULD MOVE EAST OF REGION
BY DAWN WITH CLEARING AND COOLER AS COOLER TEMPS CRASHING IN...
ESPECIALLY NW SECTIONS.  LATEST MODEL GUIDANCE NOW COOLER WHICH WAS
ALREADY INCORPORATED YESTERDAY SO CURRENT HIGHS LOOK GOOD WITH ALSO GOOD
CORRELATION OF PROGGED LOW LEVEL THERMAL FIELDS.  WILL GO WITH BREEZY
15 TO 25 MPH WINDS MID DAY WORDING BASED ON LOW LEVEL MOMENTUM MIXING
DOWN DUE TO MODERATELY STRONG CAA AND HEATING WHICH SUPPORTED BY
NORTHERN PLAINS WINDS AT THIS TIME. MINOR CHANGES SUNDAY NIGHT WILL ADD
PATCHY FROST POSSIBLE NORTH AREAS AS WINDS BECOME LIGHT AHEAD OF NEXT
WAVE.  THEN GOOD WARMUP MONDAY WITH SW WINDS BY PM FOR 30-35 DEGREE
RANGE AS WEAK SFC LOW SLIDES JUST NORTH OF AREA MONDAY NIGHT.  LIMITED
MOISTURE DOESN/T SUPPORT POPS WITH THIS DISTURBANCE AS ANY RAIN THAT
OCCURS APPEARS WILL BE NORTH OF FORECAST AREA AND LIGHT. FOR TUESDAY...
COOLER AGAIN WITH NEXT SHOT OF CANADIAN AIR WITH ONLY MINOR CHANGES TO
CURRENT TEMPS.

.EXTENDED...(WED-SAT)
LATEST UKMET SUPPORT AVNXT/GFS SOLUTION AND NOGAPS OF EVEN STRONGER
SHORT WAVE THURSDAY WITH GOOD WARMUP WED AND MUCH COOLER LATE THU INTO
FRIDAY.  CAT LEAST CHANCE POPS AS GULF OPEN AND GOOD TRIGGER AND ALSO
POTENTIAL FOR AT LEAST SOME ADDITIONAL MOISTURE FROM ISIDORE.  NEXT 24-
36 SHOULD CLARIFY POP POTENTIAL BUT LARGER SCALE FORCING SUPPORT
WIDESPREAD POPS OF AT LEAST MODERATE AMOUNTS.

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

NICHOLS