Severe Thunderstorm Warning 104, NWS Des Moines, IA

IAZ004>007-015>017-023>028-033>039-044>050-057>062-070>075-081>086-
092>097-240200-

CENTRAL IOWA THUNDERSTORM OUTLOOK
NATIONAL WEATHER SERVICE DES MOINES IA
355 PM CDT SAT AUG 23 1997

HAZARD--ISOLATED THUNDERSTORMS POSSIBLY CONTAINING LARGE HAIL AND
WINDS TO 75 MPH.

AREA OF CONCERN--MAINLY NORTHEAST OF A LINE INCLUDING WATERLOO AND
MASON CITY.

TIMING DETAILS--BETWEEN 700 PM THIS EVENING AND 200 AM SUNDAY.

METEOROLOGICAL COMMENTS--THE ATMOSPHERE WILL CONTINUE TO BE VERY
UNSTABLE INTO THE EARLY EVENING HOURS...ESPECIALLY OVER NORTHWEST IOWA
AND SOUTHWEST MINNESOTA WHERE DEWPOINTS HAVE CLIMBED INTO THE 70S.
THUNDERSTORMS ARE LIKELY TO DEVELOP AS THIS AIR COLLIDES WITH A WARM
FRONT WHICH EXTENDS FROM ST. CLOUD MINNESOTA THROUGH THE WATERLOO
AREA. AN INCREASING SOUTHWESTERLY LOW-LEVEL JET WILL PROVIDE
CONVERGENCE ALONG THE FRONT AND FUEL INTENSE THUNDERSTORMS OVER
SOUTHEAST MINNESOTA...SOUTHWEST WISCONSIN AND NORTHEAST IOWA. THE
VERTICAL WIND PROFILE FAVORS STRONG WINDS AND HAIL WITH THESE
THUNDERSTORMS...WITH MASON CITY AND WATERLOO ON THE FRINGE OF THE MAIN
THREAT AREA. ROTATATING THUNDERSTORMS ARE ALSO POSSIBLE...WITH A SLIM
CHANCE FOR A TORNADO.

AT THIS TIME IT APPEARS THAT STORMS WILL DEVELOP NEAR OR SOUTHEAST OF
MINNEAPOLIS AROUND 700 PM. DUE TO A MODERATE NORTH FLOW ALOFT THE
STORMS SHOULD QUICKLY TRACK SOUTH-SOUTHEAST TOWARD IOWA...POSSIBLY
AFFECTING THE MASON CITY AREA BETWEEN 700 AND 1000 PM...AND
WATERLOO/CEDAR FALLS BETWEEN 900 PM AND MIDNIGHT. ALTHOUGH THE
STRONGEST THREAT OF SEVERE WEATHER IS NORTHEAST OF WATERLOO AND MASON
CITY...DAMAGING THUNDERSTORMS ARE POSSIBLE IN THIS TYPE OF SITUATION
AND TRENDS AND DEVELOPMENT WILL BE MONITORED CLOSELY.

PRECAUTIONS--SPOTTER ACTIVATION IS POSSIBLE LATER THIS EVENING...
MAINLY EAST OF I-35 AND NORTH OF HIGHWAY 20. ONCE STORMS DO
DEVELOP...MOVEMENT INTO NORTHERN IOWA MAY OCCUR QUITE RAPIDLY. ANYONE
PLANNING TO BE OUTDOORS SHOULD KEEP AN EYE ON THE NORTHERN SKY.

JUNGBLUTH

IAZ004>007-015>017-023>028-033>039-044>050-057>062-070>075-081>086-
092>097-240200-

CENTRAL IOWA THUNDERSTORM OUTLOOK
NATIONAL WEATHER SERVICE DES MOINES IA
355 PM CDT SAT AUG 23 1997

HAZARD--ISOLATED THUNDERSTORMS POSSIBLY CONTAINING LARGE HAIL AND
WINDS TO 75 MPH.

AREA OF CONCERN--MAINLY NORTHEAST OF A LINE INCLUDING WATERLOO AND
MASON CITY.

TIMING DETAILS--BETWEEN 700 PM THIS EVENING AND 200 AM SUNDAY.

METEOROLOGICAL COMMENTS--THE ATMOSPHERE WILL CONTINUE TO BE VERY
UNSTABLE INTO THE EARLY EVENING HOURS...ESPECIALLY OVER NORTHWEST IOWA
AND SOUTHWEST MINNESOTA WHERE DEWPOINTS HAVE CLIMBED INTO THE 70S.
THUNDERSTORMS ARE LIKELY TO DEVELOP AS THIS AIR COLLIDES WITH A WARM
FRONT WHICH EXTENDS FROM ST. CLOUD MINNESOTA THROUGH THE WATERLOO
AREA. AN INCREASING SOUTHWESTERLY LOW-LEVEL JET WILL PROVIDE
CONVERGENCE ALONG THE FRONT AND FUEL INTENSE THUNDERSTORMS OVER
SOUTHEAST MINNESOTA...SOUTHWEST WISCONSIN AND NORTHEAST IOWA. THE
VERTICAL WIND PROFILE FAVORS STRONG WINDS AND HAIL WITH THESE
THUNDERSTORMS...WITH MASON CITY AND WATERLOO ON THE FRINGE OF THE MAIN
THREAT AREA. ROTATATING THUNDERSTORMS ARE ALSO POSSIBLE...WITH A SLIM
CHANCE FOR A TORNADO.

AT THIS TIME IT APPEARS THAT STORMS WILL DEVELOP NEAR OR SOUTHEAST OF
MINNEAPOLIS AROUND 700 PM. DUE TO A MODERATE NORTH FLOW ALOFT THE
STORMS SHOULD QUICKLY TRACK SOUTH-SOUTHEAST TOWARD IOWA...POSSIBLY
AFFECTING THE MASON CITY AREA BETWEEN 700 AND 1000 PM...AND
WATERLOO/CEDAR FALLS BETWEEN 900 PM AND MIDNIGHT. ALTHOUGH THE
STRONGEST THREAT OF SEVERE WEATHER IS NORTHEAST OF WATERLOO AND MASON
CITY...DAMAGING THUNDERSTORMS ARE POSSIBLE IN THIS TYPE OF SITUATION
AND TRENDS AND DEVELOPMENT WILL BE MONITORED CLOSELY.

PRECAUTIONS--SPOTTER ACTIVATION IS POSSIBLE LATER THIS EVENING...
MAINLY EAST OF I-35 AND NORTH OF HIGHWAY 20. ONCE STORMS DO
DEVELOP...MOVEMENT INTO NORTHERN IOWA MAY OCCUR QUITE RAPIDLY. ANYONE
PLANNING TO BE OUTDOORS SHOULD KEEP AN EYE OJN THE NORTHERN SKY.

JUNGBLUTH

IAZ004>007-015>017-023>028-033>039-044>050-057>062-240455-

CENTRAL IOWA THUNDERSTORM OUTLOOK
NATIONAL WEATHER SERVICE DES MOINES IA
751 PM CDT SAT AUG 23 1997

HAZARD--ISOLATED SEVERE THUNDERSTORMS CAPABLE OF PRODUCING WIND
GUSTS TO 60 MPH AND LARGE HAIL.

AREA OF CONCERN--NORTHEAST OF A MASON CITY TO WATERLOO LINE.

TIMING DETAILS--BETWEEN 800 PM AND MIDNIGHT.

METEOROLOGICAL COMMENTS--A WARM FRONT OVER EASTERN IOWA THIS EVENING
WILL BE THE PRIMARY FOCUS FOR THUNDERSTORMS TO DEVELOP ALONG. THE
ATMOSPHERE ALONG THE WARM FRONTAL BOUNDARY IS VERY UNSTABLE WITH
SURFACE DEW POINTS APPROACHING 70 DEGREES. WIND PROFILES ACROSS THE
STATE INDICATE A HIGH SHEAR PROFILE WITH LOW LEVEL SOUTHWESTERLY
WINDS FEEDING THE HIGHER DEW POINT AIR INTO THE WARM FRONTAL
BOUNDARY WHILE WINDS AT THE UPPER LEVELS ARE OUT OF THE NORTHWEST.
THIS WOULD INDICATE THE POTENTIAL FOR A FEW ROTATING UPDRAFTS WITH
THE THUNDERSTORMS THIS EVENING IN NORTHEAST IOWA.  THE STORMS WILL
CONTINUE TO DEVELOP AND MOVE ALONG THE WARM FRONT OVER NORTHEAST
IOWA THIS EVENING AND EARLY TONIGHT BEFORE THE THREAT FOR SEVERE
WEATHER THREAT SHIFTS INTO ILLINOIS.

PRECAUTIONS--PRESENT INDICATIONS SUGGEST SPOTTER ACTIVATION MAY BE
REQUIRED EARLY TONIGHT IN AREAS EAST OF I35 AND NORTH OF HIGHWAY 20.
PERSONS WITH OUTDOOR ACTIVITIES THIS EVENING SHOULD KEEP ABREAST OF
THE LATEST SHORT TERM FORECASTS IN THIS AREA.

SMITH