Tornado Watch 387

URGENT - IMMEDIATE BROADCAST REQUESTED
TORNADO WATCH NUMBER 387
NWS STORM PREDICTION CENTER NORMAN OK
5:25 PM CDT THU MAY 29 2008
THE NWS STORM PREDICTION CENTER HAS ISSUED A
TORNADO WATCH FOR PORTIONS OF
EXTREME NORTHWEST IOWA
EXTREME NORTHEAST NEBRASKA
SOUTHEAST SOUTH DAKOTA
EFFECTIVE THIS THURSDAY AFTERNOON AND EVENING FROM 5:25 PM UNTIL 11:00 PM
CDT.
TORNADOES...HAIL TO 2 INCHES IN DIAMETER...THUNDERSTORM WIND
GUSTS TO 70 MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE
AREAS.
THE TORNADO WATCH AREA IS APPROXIMATELY ALONG AND 35 STATUTE
MILES NORTH AND SOUTH OF A LINE FROM 70 MILES WEST NORTHWEST OF
YANKTON SOUTH DAKOTA TO 30 MILES NORTHEAST OF SIOUX CITY IOWA.
FOR A COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH
OUTLINE UPDATE (WOUS64 KWNS WOU7).
REMEMBER...A TORNADO WATCH MEANS CONDITIONS ARE FAVORABLE FOR
TORNADOES AND SEVERE THUNDERSTORMS IN AND CLOSE TO THE WATCH
AREA. PERSONS IN THESE AREAS SHOULD BE ON THE LOOKOUT FOR
THREATENING WEATHER CONDITIONS AND LISTEN FOR LATER STATEMENTS
AND POSSIBLE WARNINGS.
DISCUSSION...VISIBLE SATELLITE IMAGERY AND SURFACE OBSERVATIONS
SUGGEST THAT THE WARM FRONT IS LIFTING SLOWLY N OF THE MO RIVER FROM
NEB INTO SD. CONVECTIVE INITIATION WILL BECOME MORE PROBABLE IN THE
NEXT COUPLE OF HOURS ACROSS SE SD AS THE LOW LEVELS
WARM/MOISTEN...WHILE VERTICAL SHEAR IS ALREADY FAVORABLE FOR
SUPERCELLS. A COUPLE OF TORNADOES WILL BE POSSIBLE WITH
SURFACE-BASED SUPERCELLS ALONG THE WARM FRONT...ALONG WITH LARGE
HAIL/DAMAGING WINDS THROUGH LATE EVENING.
AVIATION...TORNADOES AND A FEW SEVERE THUNDERSTORMS WITH HAIL
SURFACE AND ALOFT TO 2 INCHES. EXTREME TURBULENCE AND SURFACE
WIND GUSTS TO 60 KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO
500. MEAN STORM MOTION VECTOR 26030.
..THOMPSON
. IOWA COUNTIES INCLUDED ARE
PLYMOUTH SIOUX WOODBURY
NEBRASKA COUNTIES INCLUDED ARE
DAKOTA DIXON
SOUTH DAKOTA COUNTIES INCLUDED ARE
BON HOMME CHARLES MIX CLAY
DOUGLAS HUTCHINSON LINCOLN
TURNER UNION YANKTON