Severe Thunderstorm Warning 219, NWS Des Moines, IA

IAZ004>006-015-016-023>025-280400-

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE DES MOINES IA
958 PM CDT SAT JUN 27 1998

HAZARD--ISOLATED SEVERE THUNDERSTORMS...EVOLVING INTO A MORE
WIDESPREAD LINE OF STORMS...ALL CAPABLE OF DAMAGING WINDS...LARGE
HAIL AND INTENSE RAINFALL.  AN ISOLATED TORNADO IS ALSO POSSIBLE.

AREA OF CONCERN AND TIMING DETAILS--AFTER 400 PM NEAR THE
IOWA/MINNESOTA BORDER...OR NORTH OF HIGHWAY 3 AND NORTHWEST OF ALGONA
AND SAC CITY...SPREADING ACROSS MUCH OF NORTHERN IOWA...MAINLY NORTH
OF HIGHWAY 20 OVERNIGHT.

METEOROLOGICAL COMMENTS--A FRONTAL BOUNDARY LOCATED FROM SOUTHEAST
MINNESOTA THROUGH FAR NORTHWEST IOWA INTO NORTHEAST NEBRASKA WILL BE
THE PRIMARY FOCUSING MECHANISM FOR THUNDERSTORMS LATE THIS AFTERNOON
AND TONIGHT.  THE NORTHERN PART OF THE FRONT IS STILL PUSHING EAST
WHILE THE WESTERN AND SOUTHERN ENDS OF THE FRONT HAVE STALLED.  VERY
UNSTABLE AIR EXISTS ALONG AND SOUTH OF THE FRONT WITH MORE POOLING OF
MOISTURE EXPECTED TODAY ALONG THE FRONT. THE AIR MASS IS EXPECTED TO
REMAIN CAPPED UNTIL LATE THIS AFTERNOON WHEN PEAK HEATING OCCURS.
CONVERGENCE WILL BE GREATEST IN NORTHEAST NEBRASKA AND SOUTHEAST
SOUTH DAKOTA WHERE THUNDERSTORMS ARE EXPECTED TO FORM RAPIDLY AFTER
400 PM.  THEY WILL BE AIDED BY AN UPPER LEVEL TROUGH ASSOCIATED WITH
COLDER AIR ALOFT MOVING IN ON STRONGER WESTERLY JET STREAM WINDS
LOCATED NOW FROM WYOMING INTO SOUTH DAKOTA. INITIAL DEVELOPMENT WILL
LIKELY BE IN THE FORM OF CELLULAR STORMS...THEN EVOLVING INTO A
LINEAR COMPLEX WITH THE POSSIBILITY OF BOW ECHOES AND DAMAGING
STRAIGHT-LINE WINDS.  THIS OCCURRED OVER PARTS OF MINNESOTA AND
WISCONSIN LAST NIGHT.  THE TRACK WILL BE A BIT FURTHER SOUTH INTO
NORTHERN IOWA TONIGHT.  THE INSTABILITY AND DEEP MOISTURE AXIS RUNS
FROM IOWA EAST INTO NORTHERN ILLINOIS...A FAVORABLE SET UP FOR A
HEAVY RAIN EPISODE IN NORTHERN IOWA TONIGHT AS SOUTHERLY LOW-LEVEL
WINDS INCREASE TONIGHT.  THE GROUND REMAINS SATURATED OR NEARLY-SO IN
THE AREA OF CONCERN.  FLASH FLOOD POTENTIAL WILL BE MONITORED MORE
THIS AFTERNOON AS NEWER DATA BECOMES AVAILABLE.

PRECAUTIONS--SPOTTER ACTIVATION MAY BE NEEDED IN THE AREA OF
CONCERN LATE THIS AFTERNOON AND TONIGHT.  MONITOR FUTURE UPDATES
CLOSELY THIS AFTERNOON AND EVENING.  THOSE WITH INTERESTS ALONG AREA
RIVERS SHOULD PAY CLOSE ATTENTION TO THE FORECAST THAT WILL BE
UPDATED AROUND 400 PM.

KULA

IAZ004>006-015-016-023>025-280400-

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE DES MOINES IA
958 PM CDT SAT JUN 27 1998

HAZARD--ISOLATED SEVERE THUNDERSTORMS...EVOLVING INTO A MORE
WIDESPREAD LINE OF STORMS...ALL CAPABLE OF DAMAGING WINDS...LARGE
HAIL AND INTENSE RAINFALL.  AN ISOLATED TORNADO IS ALSO POSSIBLE.

AREA OF CONCERN AND TIMING DETAILS--AFTER 400 PM NEAR THE
IOWA/MINNESOTA BORDER...OR NORTH OF HIGHWAY 3 AND NORTHWEST OF ALGONA
AND SAC CITY...SPREADING ACROSS MUCH OF NORTHERN IOWA...MAINLY NORTH
OF HIGHWAY 20 OVERNIGHT.

METEOROLOGICAL COMMENTS--A FRONTAL BOUNDARY LOCATED FROM SOUTHEAST
MINNESOTA THROUGH FAR NORTHWEST IOWA INTO NORTHEAST NEBRASKA WILL BE
THE PRIMARY FOCUSING MECHANISM FOR THUNDERSTORMS LATE THIS AFTERNOON
AND TONIGHT.  THE NORTHERN PART OF THE FRONT IS STILL PUSHING EAST
WHILE THE WESTERN AND SOUTHERN ENDS OF THE FRONT HAVE STALLED.  VERY
UNSTABLE AIR EXISTS ALONG AND SOUTH OF THE FRONT WITH MORE POOLING OF
MOISTURE EXPECTED TODAY ALONG THE FRONT. THE AIR MASS IS EXPECTED TO
REMAIN CAPPED UNTIL LATE THIS AFTERNOON WHEN PEAK HEATING OCCURS.
CONVERGENCE WILL BE GREATEST IN NORTHEAST NEBRASKA AND SOUTHEAST
SOUTH DAKOTA WHERE THUNDERSTORMS ARE EXPECTED TO FORM RAPIDLY AFTER
400 PM.  THEY WILL BE AIDED BY AN UPPER LEVEL TROUGH ASSOCIATED WITH
COLDER AIR ALOFT MOVING IN ON STRONGER WESTERLY JET STREAM WINDS
LOCATED NOW FROM WYOMING INTO SOUTH DAKOTA. INITIAL DEVELOPMENT WILL
LIKELY BE IN THE FORM OF CELLULAR STORMS...THEN EVOLVING INTO A
LINEAR COMPLEX WITH THE POSSIBILITY OF BOW ECHOES AND DAMAGING
STRAIGHT-LINE WINDS.  THIS OCCURRED OVER PARTS OF MINNESOTA AND
WISCONSIN LAST NIGHT.  THE TRACK WILL BE A BIT FURTHER SOUTH INTO
NORTHERN IOWA TONIGHT.  THE INSTABILITY AND DEEP MOISTURE AXIS RUNS
FROM IOWA EAST INTO NORTHERN ILLINOIS...A FAVORABLE SET UP FOR A
HEAVY RAIN EPISODE IN NORTHERN IOWA TONIGHT AS SOUTHERLY LOW-LEVEL
WINDS INCREASE TONIGHT.  THE GROUND REMAINS SATURATED OR NEARLY-SO IN
THE AREA OF CONCERN.  FLASH FLOOD POTENTIAL WILL BE MONITORED MORE
THIS AFTERNOON AS NEWER DATA BECOMES AVAILABLE.

PRECAUTIONS--SPOTTER ACTIVATION MAY BE NEEDED IN THE AREA OF
CONCERN LATE THIS AFTERNOON AND TONIGHT.  MONITOR FUTURE UPDATES
CLOSELY THIS AFTERNOON AND EVENING.  THOSE WITH INTERESTS ALONG AREA
RIVERS SHOULD PAY CLOSE ATTENTION TO THE FORECAST THAT WILL BE
UPDATED AROUND 400 PM.

KULA

IAZ004>006-015-016-023>025-280400-

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE DES MOINES IA
959 PM CDT SAT JUN 27 1998

THE TORNADO WATCH FOR NORTHWEST AND NORTH CENTRAL IOWA HAS EXPIRED.
HOWEVER A FLASH FLOOD WATCH REMAINS IN EFFECT FOR THE REST OF
TONIGHT AS RAINS EARLIER TODAY BEGIN TO RUN OFF.

PYTLAK

IAZ004>006-015-016-023>025-280400-

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE DES MOINES IA
959 PM CDT SAT JUN 27 1998

THE TORNADO WATCH FOR NORTHWEST AND NORTH CENTRAL IOWA HAS EXPIRED.
HOWEVER A FLASH FLOOD WATCH REMAINS IN EFFECT FOR THE REST OF
TONIGHT AS RAINS EARLIER TODAY BEGIN TO RUN OFF.

PYTLAK

IAZ025-026-036-037-280405-

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE DES MOINES IA
1002 PM CDT SAT JUN 27 1998

A LINE OF THUNDERSTORMS PRODUCING 45 TO 50 MPH WINDS WILL MOVE
THROUGH WRIGHT...HAMILTON...FRANKLIN AND HARDIN COUNTIES THROUGH
1130 PM. SOME SMALL HAIL MAY OCCUR AS WELL. WINDS OF 30-40 MPH WERE
REPORTED AT CLARION AROUND 950 PM.

MYERS

IAZ025-026-036-037-280405-

SPECIAL WEATHER STATEMENT
NATIONAL WEATHER SERVICE DES MOINES IA
1002 PM CDT SAT JUN 27 1998

A LINE OF THUNDERSTORMS PRODUCING 45 TO 50 MPH WINDS WILL MOVE
THROUGH WRIGHT...HAMILTON...FRANKLIN AND HARDIN COUNTIES THROUGH
1130 PM. SOME SMALL HAIL MAY OCCUR AS WELL. WINDS OF 30-40 MPH WERE
REPORTED AT CLARION AROUND 950 PM.

MYERS