Severe Thunderstorm Warning 175, NWS Des Moines, IA

AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE DES MOINES IA
940 PM CDT SAT AUG 5 2000

PLENTY OF ACTION THIS EVENING WITH LARGE CELL PRODUCING ONE INCH TO
BASEBALL SIZED HAIL OCCURRING.

NUMEROUS BOUNDARIES TO ACT UPON AS WELL AS BEING CREATED BY THIS
EVENING ACTIVITY.  HWVR NRN PORTION OF THE STATE APPEARS TO BE OUT
OF CHC FOR SERIOUS WEATHER AS MAIN ACTIVITY RIDES BOUNDARY THROUGH
CENTRAL IA.  WINDS ALFT PICKING UP WITH MImD LVL SPEED MAX.  HAVE
UPDATED TO CLEAN UP THE NORTH WHILE ALSO RAISING MINS AS DEWPOINTS
REMAINS IN THE 70S ATTM AND INTO VERY MUGGY AIRMASS.

.DSM...NONE

FORSTER

IAZ004>007-015>017-023>028-033>039-044>050-057>062-070>075-081>086-
092>097-061100-

CENTRAL IOWA THUNDERSTORM OUTLOOK
NATIONAL WEATHER SERVICE DES MOINES IA
352 PM CDT SAT AUG 5 2000

HAZARD--A SLIGHT RISK OF SEVERE THUNDERSTORMS WITH LARGE HAIL...
DAMAGING WINDS...AN ISOLATED TORNADO...AND HEAVY RAINFALL OF 1 TO 3
INCHES.

AREA OF CONCERN--THREAT OF SEVERE THUNDERSTORMS IS GREATEST FOR
LOCATIONS MAINLY SOUTH OF HIGHWAY 30...ANYWHERE FROM DENISON TO AMES
TO TAMA AND POINTS SOUTH TO THE IOWA MISSOURI BORDER. MORE GENERAL
THUNDERSTORMS ARE FORESEEN NORTH OF HIGHWAY 30.

TIMING DETAILS--6 PM TO 10 PM CDT.

METEOROLOGICAL COMMENTS--A COMPLEX WEATHER SCENARIO IS IN PLACE
ACROSS IOWA FOR THIS EVENING. A SURFACE WARM FRONTAL BOUNDARY...
EXTENDING FROM OMAHA TO DES MOINES TO SOUTHEAST IOWA...IS THE
LEADING EDGE OF EXTREMELY UNSTABLE AIR ALONG THE BOUNDARY AND
POINTS SOUTH TO THE BORDER. AS OF LATE THIS AFTERNOON...A STRONG LID
OF WARM AIR ALOFT HAS KEPT THUNDERSTORMS FROM DEVELOPING. IN THE
MEANTIME...DEW POINTS AT THE SURFACE HAVE REACHED WELL INTO THE
70S...ESPECIALLY IN THE SOUTHERN HALF OF THE STATE. WITH THESE
INGREDIENTS IN PLACE...IF THUNDERSTORMS DEVELOP...THEY COULD RAPIDLY
BECOME SEVERE WITH STRONG WIND GUSTS...LARGE HAIL...AND FLASH
FLOODING BEING THE MAIN THREATS OF SEVERE WEATHER. VERTICAL WIND
PROFILES SUGGEST THAT A FEW SUPERCELL THUNDERSTORMS COULD DEVELOP
WITH AN ISOLATED TORNADO POSSIBLE...ESPECIALLY FOR LOCATIONS IN
SOUTHERN IOWA. FARTHER TO THE NORTH OF HIGHWAY 30...GENERAL
THUNDERSTORMS ARE EXPECTED WHERE INSTABILITY IS LESS. HOWEVER AN
ISOLATED SEVERE THUNDERSTORM CAN NOT BE RULED OUT THIS EVENING.

PRECAUTIONS--THIS EVENINGS WEATHER SITUATION REMAINS A POTENTIALLY
EXPLOSIVE ONE AS WEATHER CONDITIONS MAY CHANGE QUITE RAPIDLY.
IT WOULD BE A GOOD IDEA TO HEIGHTEN WEATHER AWARENESS...ESPECIALLY
PEOPLE PLANNING OUTDOOR ACTIVITIES.  SPOTTER ACTIVATION WILL LIKELY
BE NEEDED...MAINLY FOR LOCATIONS SOUTH OF HIGHWAY 30.  LISTEN FOR
NATIONAL WEATHER SERVICE FORECASTS AND STATEMENTS FOR UPDATED
INFORMATION. A TORNADO WATCH MAY BE ISSUED THIS EVENING.

KNOLLHOFF

IAZ004>007-015>017-023>028-033>039-044>050-057>062-070>075-081>086-
092>097-061100-

CENTRAL IOWA THUNDERSTORM OUTLOOK...UPDATED
NATIONAL WEATHER SERVICE DES MOINES IA
710 PM CDT SAT AUG 5 2000

HAZARD--SCATTERED THUNDERSTORMS WITH SOME BECOMING SEVERE. LARGE
HAIL...DAMAGING WINDS...AN ISOLATED TORNADO...AND HEAVY RAINFALL OF 1
TO 3 INCHES ARE THE MAIN SEVERE WEATHER THREATS THIS EVENING.

AREA OF CONCERN--THREAT OF SEVERE THUNDERSTORMS IS GREATEST FOR
LOCATIONS MAINLY ALONG AND SOUTH OF HIGHWAY 30...ANYWHERE FROM
DENISON TO AMES TO TAMA AND POINTS SOUTH TO THE IOWA MISSOURI BORDER.
MORE GENERAL THUNDERSTORMS ARE FORESEEN NORTH OF HIGHWAY 30...WITH
SOME POSSIBLY SEVERE.

TIMING DETAILS--6 PM TO MIDNIGHT.

METEOROLOGICAL COMMENTS--A COMPLEX WEATHER SCENARIO IS IN PLACE
ACROSS IOWA THIS EVENING. A SURFACE WARM FRONTAL BOUNDARY...
EXTENDING FROM OMAHA TO DES MOINES TO SOUTHEAST IOWA...IS THE
LEADING EDGE OF EXTREMELY UNSTABLE AIR ALONG THE BOUNDARY AND
POINTS SOUTH TO THE BORDER. AS OF EARLY THIS EVENING...A STRONG LID
OF WARM AIR ALOFT HAS KEPT WIDESPREAD THUNDERSTORM DEVELOPMENT FROM
OCCURRING SO FAR THIS EVENING. IN THE MEANTIME...DEW POINTS AT THE
SURFACE WILL REMAIN WELL INTO THE 70S...ESPECIALLY IN THE SOUTHERN
AND WESTERN PORTIONS OF THE STATE. WITH THESE INGREDIENTS IN
PLACE...DEVELOPING THUNDERSTORMS DEVELOP COULD RAPIDLY BECOME
SEVERE WITH STRONG WIND GUSTS...LARGE HAIL...FLASH FLOODING...AND
ISOLATED TORNADOES BEING THE MAIN THREATS OF SEVERE WEATHER. FARTHER
TO THE NORTH OF HIGHWAY 30...THE THREAT FOR SEVERE WEATHER IS
MINIMAL WHERE INSTABILITY IS LESS. HOWEVER AN ISOLATED TORNADIC
THUNDERSTORM CAN NOT BE RULED OUT THIS EVENING.

PRECAUTIONS--THIS EVENINGS WEATHER SITUATION REMAINS A POTENTIALLY
EXPLOSIVE ONE AS WEATHER CONDITIONS MAY CHANGE QUITE RAPIDLY.
IT WOULD BE A GOOD IDEA TO HEIGHTEN WEATHER AWARENESS...ESPECIALLY
PEOPLE PLANNING OUTDOOR ACTIVITIES.  SPOTTER ACTIVATION IS NEEDED
...MAINLY FOR LOCATIONS SOUTH OF HIGHWAY 30. LISTEN FOR NATIONAL
WEATHER SERVICE FORECASTS AND STATEMENTS FOR UPDATED INFORMATION. A
TORNADO WATCH HAS BEEN ISSUED FOR THE ENTIRE DES MOINES NATIONAL
WEATHER SERVICE AREA OF RESPONSIBILITY THIS EVENING.

KNOLLHOFF

IAZ004>007-015>017-023>028-033>039-060400-

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE DES MOINES IA
927 PM CDT SAT AUG 5 2000

THE TORNADO WATCH HAS BEEN CANCELLED FOR NORTHERN IOWA.

THE FOLLOWING COUNTIES ARE NO LONGER IN THE TORNADO WATCH...

EMMET           FRANKLIN
KOSSUTH         BUTLER
WINNEBAGO       BREMER
WORTH           SAC
PALO ALTO       CALHOUN
HANCOCK         WEBSTER
CERRO GORDO     HAMILTON
POCAHONTAS      HARDIN
HUMBOLDT        GRUNDY
WRIGHT          BLACK HAWK

SOME CITIES NO LONGER IN THE WATCH ARE..

ESTHERVILLE  FORT DODGE
ALGONA       WEBSTER CITY
MASON CITY   GRUNDY CENTER
WATERLOO     ELDORA

THE TORNADO WATCH DOES REMAIN IN EFFECT UNTIL MIDNIGHT FOR MUCH OF
CENTRAL AND SOUTHERN IOWA.

FORSTER