Hail in Iowa, June 21, 2001

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE QUAD CITIES IA IL
300 AM CDT THU JUN 21 2001

WATER VAPOR IMAGERY INDICATING VIGOROUS VORT ROTATING SOUTHEAST DOWN
ACRS EAST SD ATTM. THIS FEATURE TO BE CULPRIT OF TODAYS WEATHER
CONCERNS...WITH TIMING AND AREAL EXTENT OF PRECIP CHANCES TODAY THE
TRICK. ETA SEEMS TO BE INITIALIZING BEST WITH CURRENT VORT...BUT AVN
AND NGM NOT FAR OFF. VORT CURRENTLY KICKING UP SCATTERED CONVECTION
ACRS SOUTHERN MN AND NORTHERN WI. SHORT RANGE MODELS PROG VORT TO
DROP ACRS THE SOUTHWEST HALF OF IA THROUGH 18Z...AND THEN SHEAR
EAST ACRS CENTRAL INTO NORTH CENTRAL IL THROUGH 00Z THIS EVENING...
IN BASE OF DEEPENING GRT LKS TROUGH. LOOKING AT UPSTREAM TRENDS OF
VORT ON W/V IMAGERY...AVNS FURTHER NORTH VORT HANDLING AND SHEARING
ACRS CENTRAL IA LOOKS MORE REASONABLE...THEN ETA/NGM SOUTHWEST IA AND
NORTHERN MISSOURI PATH. THIS WOULD BRING MORE OF A CVA/POSITIVE
OMEGA PUNCH ACRS THE CWA BY THIS AFTERNOON TO SUPPORT SHOWER AND
THUNDERSTORM REDEVELOPMENT.

WILL FIRST HAVE TO WALK OUT ONGOING PRECIP ACRS SOUTH AND EAST CWA
THIS MORNING...BEFORE UPSTREAM VORT DEVELOPS OR BRINGS IN NEW
CONVECTION. AVN ENDS THIS CURRENT ACTIVITY THIS MORNING...BEFORE
NEW ROUND SWEEPS IN FROM THE NORTHWEST BY LATE MORNING ACRS NORTHERN
CWA. ETA AND NGM CONTINUE TO FLARE UP PRECIP ACRS EAST AND SOUTHEAST
CWA TODAY WITH ALMOST NO BREAK AS VORT ROTATES IN. AM LEANING TOWARD
AVN SOLUTION...BUT WILL HAVE TO WATCH SPOTTY REDEVELOPMENT ACRS
SOUTH CENTRAL IA TOWARD PRESS TIME AS IT MOVES EAST ACRS SOUTHWEST
CWA. THUNDER WORDING WARRANTED TODAY...AND ESPECIALLY THIS
AFTERNOON LIKE CURRENT PACKAGE SUGGESTS. H5 -18 TO -20 C COLD POOL
WILL LOOK TO ROTATE RIGHT OVER THE CWA THIS AFTERNOON WITH TROUGH...
INDUCING H85-H5 LAPSE RATES OF 7 C/KM OR GREATER THIS AFTERNOON. ETA
PROGS SUGGEST CAPES TO BREACH THE 1K J/KG MARK THIS AFTERNOON ACRS
MUCH OF THE CWA...AND FORECAST SOUNDINGS TAKE LI'S TO -7 AND TOTAL
TOTALS INTO THE MID 50S. SO THUNDER SEEMS A SAFE BET. AS FOR
POSSIBLE ISOLATED SEVERE...WOULDN'T BET AGAINST A VIGOROUS UPPER AIR
SYSTEM DROPPING ACRS AREA IN NORTHWEST FLOW THIS TIME OF YEAR.
COOLING MID LEVEL TEMPS ON FCST SOUNDINGS DROP WET BULB ZEROS AT
MLI TO AROUND 8500 FT BY 00Z THIS EVENING...SUPPORTING HAIL
PARAMETERS. AS SPC STATES THOUGH...WEAK SHEAR TO HINDER ANY KIND OF
STRONG UPDRAFT POTENTIAL...AS FCST SOUNDINGS BRING DEEP BUT WEAK
NORTHWEST FLOW ACRS AREA THIS AFTERNOON. CLOUD COVER AND SOME CAA
TO LEAD TO RATHER COOL HIGHS TODAY...AND SEE NO REAL REASON TO STRAY
FROM CURRENT FORECAST HIGHS IN LOW 70S. SHORT RANGE MODELS SEEM TO
WANT TO HANG ON TO PRECIP ACRS THE AREA TOO LONG TONIGHT AND INTO
TOMORROW MORNING...AND FEEL DIURNAL PROCESSES WILL END PRECIP AROUND
MIDNIGHT...IF EVEN THAT LATE.

AMPLIFIED UPPER RIDGE TO BUILD EAST ACRS THE NORTHERN PLAINS LATE
TONIGHT INTO FRI...WITH SHORT FETCH MERIDIONAL FLOW ON ITS LEE
SIDE BEING INDUCED DOWN ACRS THE UPPER MS RVR VALLEY. THIS FLOW TO
EVENTUALLY FUNNEL NVA/SUBSIDENCE DOWN ACRS THE AREA BEHIND VORT
LATE TONIGHT AND FRI...AS MAINTAINING COOL REGIME. UPPER CYCLONIC
FLOW AND LINGERING STEEP BUT LLVL LAPSE RATES...TO GENERATE CU
DEVELOPMENT ON FRI. TEMP GUIDANCE LOOKS REASONABLE AND IN AGREEMENT
WITH MID 70S FOR FRI...AND LLVL THERMAL PARAMETERS SUPPORT THESE
VALUES AS WELL WITH SOME INSOLATION. UPPER RIDGE WILL START TO ENGULF
MIDWEST OVER THE WEEKEND...BRINGINGd WARMING MODERATION.

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

JDH