Severe Thunderstorm Warning 111, NWS Des Moines, IA

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DES MOINES IA
300 AM CDT WED JUN 18 2003

PROBLEMS RELEGATED PRIMARILY TO THE FIRST PERIOD AS BOUNDARY SLIPS
THROUGH THE STATE...THEN AGAIN BY THE LATE WEEKEND INTO NEXT WEEK AS
WESTERN TROF DEVELOPS.  FRONT IS CURRENTLY MOVING INTO NORTHERN IA
WITH MINIMAL FORCING AS MAIN SHORTWAVE ENERGY REMAINING WELL TO THE
NORTH.  THE WEAK INSTABILITY AND SHEAR HAS PRODUCED ONLY ISOLATED
CONVECTION AND MOST OF THIS HAS REMAINED OUTSIDE OF THE CWA.  THIS
BOUNDARY WILL CONTINUE TO SLIDE ACRS THE STATE TODAY AS SFC RIDGE
BUILDS INTO THE NORTHERN MIDWEST.  INSTABILITY WILL INCREASE ALONG
AND AHEAD OF THE BOUNDARY WITH CAPES OVER 1000J/KG BY MIDDAY.  SHEAR
WILL REMAIN MINIMAL SO ORGANIZED SEVERE CONVECTION IS NOT
ANTICIPATED. SIMILAR SCENARIO TO YESTERDAY WITH MAIN THREAT FROM
LOCALIZED HEAVY RAINFALL WITH SLOW MOVING STORMS.  TEMPERATURES
SHOULD RISE NICELY IN WARM SECTOR AHEAD OF THE FRONT AND HAVE GONE
WITH HIGHER FWC/MET FOR MOST LOCATIONS.

A RELATIVELY STRONG SFC RIDGE WILL SLIDE INTO THE MIDWEST TONIGHT
AND LINGER THROUGH EARLY SATURDAY.  MOST OF THE CWA WILL SEE A
NORTHERLY FLOW TONIGHT BECOMING MORE EASTERLY BY LATE IN THE WORK
WEEK. THIS WILL IMPART DRY CONDITIONS AND MODERATE TEMPERATURES ACRS
THE STATE THROUGH THE END OF THE WEEK AS A LONG WAVE TROF GRADUALLY
SETS UP ACRS THE WESTERN US. THE TROF WL EVENTUALLY DRAW MOISTURE
BACK INTO THE STATE AND AVN DEVELOPS CONVECTION AS THE THETA-E
ADVECTION INCREASES ON SATURDAY. OTHER MODELS NOT AS AGGRESSIVE WITH
CONVECTION AND WL CONTINUE TO HOLD OFF ON PCPN FOR SATURDAY.  THE
REMAINDER OF THE EXTENDED APPEARS IN FAIRLY GOOD SHAPE AS SEVERAL
SHORTWAVES EJECT OUT OF THE WESTERN TROF WITH TIMING BECOMING THE
PRIMARY ISSUE.

.DSM...NONE

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IAZ004>007-015>017-023>028-033>039-044>050-057>062-070>075-081>086-
092>097-191100-

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE DES MOINES IA
545 AM CDT WED JUN 18 2003

THIS HAZARDOUS WEATHER OUTLOOK IS FOR CENTRAL IOWA.

.DAY ONE...TODAY AND TONIGHT

A COLD FRONT WILL PUSH THROUGH CENTRAL IOWA TODAY PRODUCING
SCATTERED SHOWERS AND THUNDERSTORMS.  WEAK TO MODERATE INSTABILITY
IS FORECAST BY MIDDAY WITH SHEAR REMAINING WEAK.  THEREFORE...ANY
SEVERE STORMS WILL REMAIN ISOLATED WITH THE MAIN THREAT FROM LARGE
HAIL. HOWEVER...THE SLOW MOVEMENT OF THE STORMS WILL ALLOW MODERATE
TO HEAVY RAINFALL TO OCCUR IN ISOLATED LOCATIONS...WHERE UP TO 2
INCHES OF RAIN MAY FALL IN A SHORT PERIOD OF TIME.  THE FRONT WILL
PUSH SOUTH OF THE STATE THIS EVENING WITH THE THREAT OF
THUNDERSTORMS ENDING BY EARLY EVENING.

.DAYS TWO THROUGH SEVEN...THURSDAY THROUGH TUESDAY

ADDITIONAL CHANCES FOR THUNDERSTORMS ARE EXPECTED FROM SUNDAY INTO
TUESDAY OF NEXT WEEK.  SOME SEVERE WEATHER MAY OCCUR WITH THESE
STORMS...HOWEVER THE TIMING AND EXTENT IS NOT KNOWN.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION IS NOT ANTICIPATED AT THIS TIME.

&&

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

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