Severe Thunderstorm Warning 80, NWS Des Moines, IA

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DES MOINES IA
340 PM CDT TUE MAY 13 2003

MAIN FORECAST CHALLENGE WILL BE IN THE SHORT TERM WITH AN ACTUAL DRY
SPELL STILL POSSIBLE LATE THIS WEEK INTO VERY EARLY NEXT WEEK.
MODELS FAIRLY CLOSE ON LARGER SCALE FEATURES THAT WOULD AFFECT OUR
WEATHER AND HAVE OVERALL USED A MODEL BLEND.

VIGOROUS SHORT WAVE TROUGH TO MOVE ACROSS THE NORTHERN PLAINS THIS
EVENING AND INTO IA WEDNESDAY. STRONG DEEP LAYERED QG FORCING THIS
AFTERNOON THROUGH 06Z ACROSS THE AREA. MODELS HAVE OVERFORECAST THE
AMOUNT OF LOW LEVEL MOISTURE RETURN UP THE MO RIVER VALLEY INTO
WESTERN IA. STILL A DECENT AREA OF LOW LEVEL CONVERGENCE AND DEEPER
LAYERED CAPE TO OUR WEST WILL SUPPORT THE CONTINUATION OF STRONG
STORMS W OF THE CWA THROUGH THE AFTERNOON AND VERY EARLY EVENING.
OUR AREA DOES HAVE SOME ELEVATED INSTABILITY COUPLED WITH MODEST
MOISTURE TRANSPORT AND MODERATE SPEED SHEAR WHICH WILL SUPPORT AN
MCS TYPE SYSTEM MOVING ACROSS THE CWA THIS EVENING AND EARLY
OVERNIGHT. I SUSPECT THE SYSTEM WILL WEAKEN AS IT MOVES E INTO IA AS
ALL MODELS DIMINISH THE ELEVATED INSTABILITY BY 06Z. NORTHERN ZONES
WILL HAVE BEST SHOT FOR PCPN SUPPORTED BY STRONG KINEMATIC FORCING
AND UPPER DIVERGENCE. THE PCPN AREA SHOULD SWEEP E AND NE OF OUR
AREA BY LATE TONIGHT WITH MAINLY DRY CONDITIONS EXPECTED THROUGH
MOST OF THE MORNING. AS THE UPPER LOW DROPS SE OVER IA WEDS...THERE
SHOULD BE ADDITIONAL SHOWERS THAT MOVE S OVER THE AREA DURING MAINLY
THE AFTERNOON AND EVENING. WILL END ALL POPS BY MIDNIGHT THURS.

AREA WILL THEN REMAIN UNDER WEAK UPPER RIDGING LATE IN THE WEEK AND
DURING THE WEEKEND. LOOKS LIKE MOST CONVECTIVE ACTIVITY WILL BE
CONFINED TO THE CENTRAL AND NORTHERN PLAINS. NEXT FRONTAL BOUNDARY
LOOKS TO MOVE INTO IA TUESDAY WHICH WILL BRING OUR NEXT CHANCE FOR
RAIN. TIL THEN...LOW LEVEL SE FLOW AND MODERATE H850 TEMPS WILL KEEP
TEMPS NEAR SEASONAL NORMS.

.DSM...NONE

JAW

IAZ004>007-015>017-023>028-033>039-044>050-057>062-070>075-081>086-
092>097-141100-

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE DES MOINES IA
818 PM CDT TUE MAY 13 2003

THIS HAZARDOUS WEATHER OUTLOOK IS FOR CENTRAL IOWA.

.DAY ONE...TONIGHT

LOW PRESSURE WILL DROP SOUTHEAST INTO THE MID MISSOURI VALLEY
TONIGHT.  AN AREA OF THUNDERSTORMS OVER WESTERN IOWA INTO NORTH
CENTRAL KANSAS WILL MOVE EAST ACROSS MUCH OF CENTRAL IOWA OVERNIGHT.
ENOUGH INSTABILITY IS PRESENT TO MAINTAIN SOME SEVERE STORMS PRIOR
TO MIDNIGHT.  DYNAMICS WILL WEAKEN RAPIDLY BY MIDNIGHT AND SHOULD
END THE SEVERE THREAT.  THE PRIMARY THREAT WILL BE FROM LARGE HAIL
AND DAMAGING WINDS.

MOISTURE RACING NORTH INTO THE SYSTEM WILL PRODUCE LOCALLY HEAVY
RAINFALL.  RAINFALL FROM ONE TO ONE AND A HALF INCHES IS POSSIBLE
WITH LOCALIZED HIGHER AMOUNTS.  CONTINUE TO MONITOR THE WEATHER FOR
ADDITIONAL UPDATES ON THIS APPROACHING SYSTEM.

.DAYS TWO THROUGH SEVEN...WEDNESDAY THROUGH MONDAY

SCATTERED SHOWERS AND ISOLATED THUNDERSTORMS ARE EXPECTED ON
WEDNESDAY...ESPECIALLY BY AFTERNOON AS DAYTIME HEATING DESTABILIZES
THE ATMOSPHERE.  HOWEVER...NO SEVERE WEATHER IS EXPECTED AT THIS
TIME.  RELATIVELY TRANQUIL WEATHER IS THEN FORECAST FOR THE
REMAINDER OF THE OUTLOOK PERIOD.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION MAY BE NEEDED WEST OF INTERSTATE 35 AND SOUTH OF
U.S. HIGHWAY 20 BEFORE MIDNIGHT.
&&

MORE INFORMATION CAN BE OBTAINED AT WWW.CRH.NOAA.GOV/DMX (ALL LOWER CASE).

MS MAY 03

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE DES MOINES IA
0728 PM CDT TUE MAY 13 2003

TIME(CDT)  .....CITY LOCATION.....STATE   ...EVENT/REMARKS...
           ....COUNTY LOCATION....

0702 PM    2 E BREDA                 IA   0.88 IN HAIL
05/13/03   CARROLL

0710 PM    2 E BREDA                 IA   0.88 IN HAIL
05/13/03   CARROLL

SJT

PRELIMINARY LOCAL STORM REPORT
NATIONAL WEATHER SERVICE DES MOINES IA
0807 PM CDT TUE MAY 13 2003

TIME(CDT)  .....CITY LOCATION.....STATE   ...EVENT/REMARKS...
           ....COUNTY LOCATION....

0720 PM    1 N LIDDERDALE            IA   1.75 IN HAIL
05/13/03   CARROLL

SJT