Severe Thunderstorm Warning 193, NWS Des Moines, IA

IAZ004-005-015-023-024-033>037-044>050-057>062-070>075-081>086-
092>097-202200-

CENTRAL IOWA THUNDERSTORM OUTLOOK
NATIONAL WEATHER SERVICE DES MOINES IA
1152 AM CDT SAT JUN 20 1998

HAZARD--SCATTERED THUNDERSTORMS...SOME CAPABLE OF PRODUCING HAIL UP
TO 2 INCHES IN DIAMETER...WINDS TO 80 MPH...AND RAINFALL AMOUNTS OF
1 TO 2 INCHES.

AREA OF CONCERN AND TIMING DETAILS--THE ENTIRE FORECAST AREA WILL BE
AFFECTED.  THE THREAT WILL LIKELY NOON TO 500 PM WEST OF A LINE FROM
MASON CITY TO ATLANTIC...AND FROM 500 PM UNTIL 1100 PM EAST
OF THAT.

METEOROLOGICAL COMMENTS--A DYNAMIC WEATHER SITUATION WILL DEVELOP
FROM MID AFTERNOON INTO THE EVENING. THUNDERSTORMS SHOULD FORM A
SOLID LINE ALONG A COLD FRONT AS IT SWEEPS ACROSS THE STATE BY SUNDAY
MORNING. AT MIDDAY THE COLD FRONT HAD PUSHED INTO THE NORTHWEST
COUNTIES OF IOWA WITH VERY WARM AND UNSTABLE AIR TO ITS EAST.  DEW
POINTS IN THE 70S ARE PRODUCING STRONG INSTABILITY ACROSS IOWA WITH
CAPE VALUES IN EXCESS OF 5000 J/KG AND LIFTED INDICES AROUND MINUS 12
DEGREES C.  ONLY A WARM LAYER OF AIR ALOFT AROUND 5000 FEET IS
HOLDING BACK THE THUNDERSTORMS AT THIS TIME...BUT THE INSTABILITY
WILL BE RELEASED AS THE COLD FRONT AND A MID-LEVEL JET STREAM MOVE
THROUGH.

TODAYS ENVIRONMENT IS MOST FAVORABLE FOR TORRENTIAL RAINS AND
DAMAGING STRAIGHT LINE WINDS...ALTHOUGH A BRIEF TORNADO AND LARGE
HAIL CANNOT BE RULED OUT DUE TO THE STRONG INSTABILITY. RAINFALL
RATES WILL BE HIGH...BUT THE PROGRESSIVE MOVEMENT OF THE LINE SHOULD
LIMIT MOST RAIN AMOUNTS TO THE 1 TO 2 INCH RANGE.

PRECAUTIONS -PEOPLE WITH WEATHER SENSITIVE ACTIVITIES OR INTERESTS
SHOULD KEEP WATCH FOR FURTHER UPDATES. THE WEATHER SITUATION COULD
CHANGE QUICKLY LATER THIS AFTERNOON AND SEVERE WEATHER WATCHES ARE
LIKELY ACROSS MUCH OF IOWA. SPOTTER ACTIVATION WILL LIKELY BE
REQUIRED SO MONITOR SHORT TERM FORECASTS FOR TIMING INTO ANY SPECIFIC
AREA. PROLONGED HEAVY RAINS ARE NOT EXPECTED...BUT DUE TO SATURATED
GROUND AND HIGH WATER LEVELS...SMALL STREAM FLOODING AND PONDING OF
WATER IS POSSIBLE.

JUNGBLUTH

IAZ004-005-015-023-024-033>037-044>050-057>062-070>075-081>086-
092>097-202200-

CENTRAL IOWA THUNDERSTORM OUTLOOK
NATIONAL WEATHER SERVICE DES MOINES IA
1152 AM CDT SAT JUN 20 1998

HAZARD--SCATTERED THUNDERSTORMS...SOME CAPABLE OF PRODUCING HAIL UP
TO 2 INCHES IN DIAMETER...WINDS TO 80 MPH...AND RAINFALL AMOUNTS OF
1 TO 2 INCHES.

AREA OF CONCERN AND TIMING DETAILS--THE ENTIRE FORECAST AREA WILL BE
AFFECTED.  THE THREAT WILL LIKELY NOON TO 500 PM WEST OF A LINE FROM
MASON CITY TO ATLANTIC...AND FROM 500 PM UNTIL 1100 PM EAST
OF THAT.

METEOROLOGICAL COMMENTS--A DYNAMIC WEATHER SITUATION WILL DEVELOP
FROM MID AFTERNOON INTO THE EVENING. THUNDERSTORMS SHOULD FORM A
SOLID LINE ALONG A COLD FRONT AS IT SWEEPS ACROSS THE STATE BY SUNDAY
MORNING. AT MIDDAY THE COLD FRONT HAD PUSHED INTO THE NORTHWEST
COUNTIES OF IOWA WITH VERY WARM AND UNSTABLE AIR TO ITS EAST.  DEW
POINTS IN THE 70S ARE PRODUCING STRONG INSTABILITY ACROSS IOWA WITH
CAPE VALUES IN EXCESS OF 5000 J/KG AND LIFTED INDICES AROUND MINUS 12
DEGREES C.  ONLY A WARM LAYER OF AIR ALOFT AROUND 5000 FEET IS
HOLDING BACK THE THUNDERSTORMS AT THIS TIME...BUT THE INSTABILITY
WILL BE RELEASED AS THE COLD FRONT AND A MID-LEVEL JET STREAM MOVE
THROUGH.

TODAYS ENVIRONMENT IS MOST FAVORABLE FOR TORRENTIAL RAINS AND
DAMAGING STRAIGHT LINE WINDS...ALTHOUGH A BRIEF TORNADO AND LARGE
HAIL CANNOT BE RULED OUT DUE TO THE STRONG INSTABILITY. RAINFALL
RATES WILL BE HIGH...BUT THE PROGRESSIVE MOVEMENT OF THE LINE SHOULD
LIMIT MOST RAIN AMOUNTS TO THE 1 TO 2 INCH RANGE.

PRECAUTIONS -PEOPLE WITH WEATHER SENSITIVE ACTIVITIES OR INTERESTS
SHOULD KEEP WATCH FOR FURTHER UPDATES. THE WEATHER SITUATION COULD
CHANGE QUICKLY LATER THIS AFTERNOON AND SEVERE WEATHER WATCHES ARE
LIKELY ACROSS MUCH OF IOWA. SPOTTER ACTIVATION WILL LIKELY BE
REQUIRED SO MONITOR SHORT TERM FORECASTS FOR TIMING INTO ANY SPECIFIC
AREA. PROLONGED HEAVY RAINS ARE NOT EXPECTED...BUT DUE TO SATURATED
GROUND AND HIGH WATER LEVELS...SMALL STREAM FLOODING AND PONDING OF
WATER IS POSSIBLE.

JUNGBLUTH