[LeArc] Forecast Discussion : MLI@ 6/30/2003 2:18:53 PM

[learc@mailman.qth.net]

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


FXUS63 KDVN 301915
AFDMLI

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
210 PM CDT MON JUN 30 2003

.OVERVIEW...WEAK HIGH PRESSURE STILL IN PLACE ACROSS AREA WITH
DEWPOINTS IN THE 50S AT 18Z.  UPPER AIR AND SURFACE ANALYSIS SHOWS
LITTLE CHANGE...TROPICAL STORM BILL TO MOVE INTO LOWER OHIO VALLEY
NEXT 36 HOURS.  THIS WILL KEEP REGION UNDER LIGHT EASTERLY FLOW AND
WEAK SURFACE RIDGE.  SLOW MODIFICATION OF AIRMASS REASONABLE NEXT
COUPLE OF DAYS.  QUIET...SEASONABLE WEATHER THROUGH WEDNESDAY NIGHT.

...TEMPERATURES NEXT FEW DAYS NEAR TERM CHALLENGE WITH LATE WEEK
MOISTURE MEDIUM RANGE ISSUE...

.DIAGNOSIS (DAYS 1-3)...MODELS SIMILAR HANDLING LARGER SCALE FEATURES
WITH ONLY MINOR DIFFERENCES...SO FAIR WEATHER AND DRY CONDITIONS.
PERSISTENCE MAIN GUIDANCE TONIGHT FOR TEMPS AS LOW DEWPOINTS IN AREA
SUPPORT MINS A FEW DEGREES BELOW GUIDANCE BLEND.  THEN...HIGHS WITH
LOTS OF SUN AGAIN NEAR TO A DEGREE OR TWO ABOVE BLEND.  THEN TREND
TOWARD MODEL BLEND WEDNESDAY.  DAY 3...ALL SOLUTIONS SUPPORT SLOW
MOVING COOL FRONT LATE THURSDAY WITH SURFACE WAVE.  REVIEWING THERMAL
AND KINEMATIC PARAMETERS CONTINUE TO SHOW FAVORABLE ENVIRONMENT FOR
ORGANIZED CONVECTION WITH BOWING SEGMENTS (BOW ECHOES) OR POSSIBLY
DERECHO NORTH HALF.  HIGH BUOYANCY (CAPE AOA 2500...LI'S -6 OR LOWER)
WITH LOTS OF MOISTURE (SFC DEWPOINTS 65-70F WITH 850 DEWPOINTS +14 TO
+18C).  THEN ADD MODERATE MID LEVEL WINDS OF 30-40 KTS MAKE ORGANIZED
CONVECTION A CERTAINLY WITH ONLY QUESTION TIMING AND LOCATIONS.  GO
40 POPS THURSDAY NIGHT NORTHWEST ONE HALF AND 30 POPS ELSEWHERE WITH
LATE WORDING.  OPT TO KEEP FOG OUT OF FORECAST TONIGHT WITH AREA
VISIBILITIES OF 3 TO 6 MILES DUE TO LOWER DEWPOINTS.

.EXTENDED (FRI-MON)...MODERATE ZONAL FLOW WITH EMBEDDED DISTURBANCES
ALOFT AND SURFACE BOUNDARIES NEARBY SUGGESTED BY ALL MEDIUM RANGE
MODELS FOR ACTIVE PERIOD.  CONDITIONS REMAIN FAVORABLE FOR ORGANIZED
CONVECTIVE EVENTS WITH MID LEVEL WINDS OF 30-50 KNOTS.  ADD VERY WARM
LOW LEVEL THERMAL FIELDS TO THIS ENVIRONMENT...ALONG WITH DEWPOINTS
NEAR 70 (HIGH INSTABILITY AND MOISTURE) BOWING SEGMENTS AND POSSIBLY
DERECHOES...OR LARGER SCALE HIGH WIND SYSTEMS. PRELIMINARY
CALCULATIONS CONTINUE TO SUGGEST MAX WIND POTENTIAL OF 70 MPH OR MORE
WITH SOME HAIL...WILL UPDATE HWODVN FOR THIS RISK AND KEEP CHANCE
SHOWERS STORMS THROUGH SUNDAY.  KEEP MONDAY DRY FOR NOW AS SUGGESTION
NW FLOW RETURNS AND BOUNDARIES SLIDE SOUTH BY THEN. TEMPS WITHIN 1
CATEGORY OF MEX...MAINLY ON HIGH SIDE THU/FRI.  TOMORROW SHOULD HAVE
MUCH BETTER IDEA OF MAGNITUDES...TIMING AND INTENSITY OF CONVECTION.

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

$$

NICHOLS