Severe Thunderstorm Warning 104, NWS Des Moines, IA

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DES MOINES IA
400 AM CDT FRI JUN 6 2003

NOT MANY CHANGES MADE TO GOING FORECAST AS THINGS UNFOLDING AS
PROGGED.  UPPER SYSTEM OVER THE ERN DKTAS WILL SINK SOUTHEAST INTO
NEBRASKA THEN PUSH EAST ACROSS NORTHERN IOWA BY MID AFTERNOON.
THERE ARE A COUPLE CONCERNS FOR TODAY.  THERE IS A POTENT VORT MAX
ASSOCIATED WITH THIS LOW AS WELL AS SOME DECENT SHEAR AS THE UPPER
LOW MOVES EAST.  IF WE GET A COUPLE HOURS OF SUNSHINE...INSTABILITY
SHOULD BE ENOUGH TO GO SURFACE BASED AND I CANNOT RULE OUT THE
THREAT FOR A STRONG TO SEVERE STORM OR TWO ACROSS THE CWA LATER THIS
MORNING.  THE SYSTEM SHIFTS EAST BY LATE IN THE DAY AND THINGS BEGIN
TO CLEAR DURING THE EARLY EVENING.  THE NEXT SYSTEM REMAINS ON TRACK
AS THE NEXT UPSTREAM SYSTEM IN NWRN SASKATCHEWAN DEVELOPS AN UPR LOW
IN SERN NEB. THIS SYSTEM MOVES ACROSS THE STATE SATURDAY NIGHT AND
SUNDAY.  WE COULD ALSO SEE SOME THREAT SOME ISOLATED SEVERE STORMS
SATURDAY NIGHT WITH THIS SYSTEM.

I BACKED OFF ON HIGHS TODAY AND AGAIN ON SUNDAY TO ACCOUNT FOR THE
CLOUD COVER OTHERWISE TEMPS HAVE NOT BEEN CHANGED FROM GOING
FORECAST.  NO CHANGES WERE MADE TO THE EXTENDED AT THIS TIME.

.DSM...NONE

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IAZ004>007-015>017-023>028-033>039-044>050-057>062-070>075-081>086-
092>097-071100-

HAZARDOUS WEATHER OUTLOOK
NATIONAL WEATHER SERVICE DES MOINES IA
530 AM CDT FRI JUN 6 2003

THIS HAZARDOUS WEATHER OUTLOOK IS FOR CENTRAL IOWA.

.DAY ONE...TODAY AND TONIGHT

WIDESPREAD LIGHT RAIN WILL FALL OVER AREAS EAST OF I-35 AND NORTH OF
HIGHWAY 20 THROUGH EARLY MORNING.  ADDITIONAL RAINFALL AMOUNTS ARE
EXPECTED TO BE AROUND A TENTH OF AN INCH.

BY LATE MORNING...SCATTERED THUNDERSTORMS ARE EXPECTED TO DEVELOP
ACROSS CENTRAL IOWA AS A LARGE UPPER LEVEL LOW PRESSURE SYSTEM MOVES
ACROSS IOWA.  THERE IS SOME POTENTIAL FOR SEVERE WEATHER LATER THIS
MORNING INTO THE AFTERNOON WITH SOME OF THE STORMS IF WE CAN GET
SOME SUNSHINE TO BREAK THROUGH THE CLOUDS AND INCREASE THE
DESTABILIZATION OF THE AIRMASS THAT IS IN PLACE.  THERE IS A FAIR
AMOUNT OF MOISTURE IN PLACE AND SOME SHEAR WILL OCCUR WITH THE LOW
AS IT MOVES EAST.  THERE IS STILL SOME QUESTION WHETHER THERE WILL
BE LONG ENOUGH BREAKS IN THE CLOUD COVER FOR THE SUN TO HEAT THE
SURFACE AND DESTABILIZE THE AIRMASS ENOUGH FOR THE STORMS TO GO
SEVERE.  THE MAIN SEVERE THREAT WOULD BE LARGE HAIL AND DAMAGING
WIND.  TIMING DETAILS ON THE POTENTIAL FOR SEVERE WEATHER WOULD
PLACE THE BEST CHANCE BETWEEN 10 AM AND 3 PM.

.DAYS TWO THROUGH SEVEN...SATURDAY THROUGH THURSDAY

ANOTHER LOW PRESSURE SYSTEM IS FORECAST TO MOVE ACROSS CENTRAL IOWA
SATURDAY NIGHT INTO SUNDAY.  THIS SYSTEM WILL HAVE A TRACK THAT IS A
LITTLE FURTHER SOUTH THAN THE ONE FOR LATER THIS MORNING AND
AFTERNOON. THE STRENGTH OF THE SYSTEM ON SATURDAY NIGHT AND SUNDAY
WILL ALSO BE WEAKER THAN TODAYS STORM SYSTEM.  WITH WEAK SHEAR AND
LIMITED MOISTURE SEVERE WEATHER IS NOT ANTICIPATED AT THIS TIME.

ANOTHER SYSTEM IS FORECAST TO MOVE ACROSS CENTRAL IOWA TUESDAY NIGHT
AND WEDNESDAY BUT IT IS TOO EARLY TO ASSESS THE SEVERE POTENTIAL OF
THIS SYSTEM.

.SPOTTER INFORMATION STATEMENT...

SPOTTER ACTIVATION MAY BE NEEDED LATE THIS AFTERNOON ACROSS CENTRAL
IOWA.  ADDITIONAL SPOTTER ACTIVATION IS POSSIBLE INTO SATURDAY NIGHT
AND SUNDAY AS THE NEXT SYSTEM MOVES THROUGH THE STATE.
&&

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

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