Severe Thunderstorm Warning 99, NWS Des Moines, IA

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DES MOINES IA
108 PM CDT SUN JUN 25 2000

...SEVERE AND FLOODING POTENTIAL TONIGHT MAIN CHALLENGE THIS
PACKAGE...

FINISHED PRELIMINARY ZONES BY NOON AND MAY HAVE TO ADJUST PACKAGE
SLIGHTLY AT PRESS TIME FOR ONGOING CONVECTION AND ANY CONVECTIVE OR
WATER WATCHES.

ANYWAY HARD TO MISS POTENTIAL FOR CONVECTION ACROSS CWA AND
SURROUNDING STATES WITH ONGOING CONVECTION.  SATELLITE AND PROGGED
SOUNDINGS INDICATE GREAT INSTABLILITY WITH DIMINISHED OR CINH GONE.
THETA E CONV BULLSEYE OVER WRN IA INTO NEB.  PWATS FROM DERIVED
SOUNDINGS IN THE 1.5 TO 2.0 INCH RANGE TOO.  LOOKS LIKE CONVECTION
SHOULD BECOME LINEAR ALONG OR AHEAD OF FRONT AND BE OVER IN NW CWA
BY MIDNIGHT.  BEST CHANCES FOR HEAVY RAIN TO BE WC INTO C AND SW
CWA.  AGAIN...WILL LIKELY NEED FFA FOR SW 1/2 OR 1/3 CWA.

MAY BE TOUGH TO GET PRECIP OUT OF SE CWA BY DAWN...BUT THAT'S HOW
I'M GOING TO TRY IT FOR NOW.  AGAIN...BY PRESS TIME...I MAY HAVE TO
ADD A 40 OR 50 POP TO MONDAY MORNING.

TEMPS ON MONDAY TO BE NEAR FAN NUMBERS WITH RAIN COOLED AIR AND WET
GROUND.  FARTHER OUT WILL GO NEAR COMP.

NEXT WEATHER MAKER COULD BE TUES NIGHT...BUT WILL CONT WITH DRY FCST
FOR NOW.  WILL RUN CHC SHRA/TSRA WED INTO THURS WITH MOISTURE
RETURN...S/W TROFS MOVING OVER IA WITH HUDSON'S BAY VORTEX STILL IN
PLACE...AND SO FORTH.  WILL KEEP TEMPS IN 70S FOR MOST PART UNTIL
WARMER AND DRY FRI.

.DSM...FLASH FLOOD WATCH THROUGH TONIGHT FOR SRN HALF OF DSM CWA...OR
IAZ033>035-044>050-057>062-070>075-081>086-092>097.

SEARCY

IAZ004>007-015>017-023>028-033>039-044>050-057>062-070>075-081>086-
092>097-261100-

CENTRAL IOWA THUNDERSTORM OUTLOOK...UPDATED
NATIONAL WEATHER SERVICE DES MOINES IA
1230 PM CDT SUN JUN 25 2000

HAZARD--NUMEROUS THUNDERSTORMS PRODUCING HEAVY RAINFALL.  A FEW OF
THE STORMS MAY BECOME SEVERE WITH WIND GUSTS OF UP TO 80 MPH AND
HAIL AN INCH OR LARGER IN DIAMETER.

TIMING--THIS AFTERNOON INTO TONIGHT.

AREA OF CONCERN--ALONG AND NORTHWEST OF A FOREST CITY TO FORT DODGE
TO AUDUBON LINE THIS AFTERNOON.  THEN ALL OF THE CENTRAL THIRD OF
IOWA AFTER 3 OR 4 PM THROUGH THE OVERNIGHT HOURS.

METEOROLOGICAL COMMENTS--A COMPLEX OF THUNDERSTORMS THAT DEVELOPED
OVER SOUTH DAKOTA OVERNIGHT WILL CONTINUE TO MOVE EAST THROUGH
SOUTHERN MINNESOTA THIS AFTERNOON AND DISSIPATE.  HOWEVER...THE
ATMOSPHERE CONTINUES TO RECOVER OVER NORTHEAST NEBRASKA AND
NORTHWEST IOWA...WITH INSTABILITY AND MOISTURE CONVERGENCE
INCREASING.  THESE STORMS WILL INITIALLY MOVE RATHER SLOW TO THE
EAST...AND WITH QUITE PLENTIFUL MOISTURE IN THE ATMOSPHERE...SOME
HEAVY RAIN IS POSSIBLE...WITH LOCAL 2 TO 4 INCH AMOUNTS POSSIBLE.
THE STORMS WILL LIKELY EVOLVE INTO BOW ECHOS WITH HIGH WINDS AND
SOME HAIL OCCURRING...ESPECIALLY OVER THE WESTERN HALF OF THE STATE
THROUGH MID AFTERNOON.  BY LATE AFTERNOON INTO THE EVENING HOURS...
CONVERGENCE OF MOISTURE WILL INCREASE AGAIN OVER NORTHEAST NEBRASKA
INTO WESTERN IOWA AS A COLD FRONT SLIDES INTO THE REGION.  AT THAT
POINT A LARGE AREA OF THUNDERSTORMS SHOULD FORM A LINE FROM NORTHERN
IOWA INTO SOUTHEAST NEBRASKA AND MOVE SOUTHEAST WITH HEAVY
RAIN...HIGH WINDS...AND LARGE HAIL A DISTINCT POSSIBILITY.

PRECAUTIONS--SPOTTER ACTIVATION WILL BE NEEDED THIS AFTERNOON INTO
THE OVERNIGHT HOURS FOR BOTH SEVERE WEATHER AND POTENTIAL FLASH
FLOODING.  PEOPLE SHOULD MONITOR LOCAL MEDIA OUTLETS OR NOAA WEATHER
RADIO TO REMAIN ABREAST OF FURTHER DEVELOPMENTS.
p

SEARCY