WATCHES: Severe Thunderstorm Watch Number 583

WWUS20 KWNS 141943
SEL3
SPC WW 141943
IAZ000-MNZ000-NEZ000-SDZ000-150200-

URGENT - IMMEDIATE BROADCAST REQUESTED
SEVERE THUNDERSTORM WATCH NUMBER 583
NWS STORM PREDICTION CENTER NORMAN OK
240 PM CDT TUE JUL 14 2009

THE NWS STORM PREDICTION CENTER HAS ISSUED A
SEVERE THUNDERSTORM WATCH FOR PORTIONS OF

NORTHWEST IOWA
SOUTHWEST AND CENTRAL MINNESOTA
EXTREME NORTHEAST NEBRASKA
EASTERN SOUTH DAKOTA

EFFECTIVE THIS TUESDAY AFTERNOON AND EVENING FROM 240 PM UNTIL
900 PM CDT.

HAIL TO 2 INCHES IN DIAMETER...THUNDERSTORM WIND GUSTS TO 70
MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE AREAS.

THE SEVERE THUNDERSTORM WATCH AREA IS APPROXIMATELY ALONG AND 70
STATUTE MILES EAST AND WEST OF A LINE FROM 10 MILES NORTH
NORTHEAST OF ALEXANDRIA MINNESOTA TO 30 MILES SOUTHEAST OF
YANKTON SOUTH DAKOTA. FOR A COMPLETE DEPICTION OF THE WATCH SEE
THE ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU3).

REMEMBER...A SEVERE THUNDERSTORM WATCH MEANS CONDITIONS ARE
FAVORABLE FOR 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. SEVERE THUNDERSTORMS CAN AND OCCASIONALLY
DO PRODUCE TORNADOES.

DISCUSSION...THUNDERSTORMS ARE DEVELOPING ALONG THE SURFACE COLD
FRONT AND A PRE-FRONTAL TROUGH ACROSS ERN SD...AND THIS ACTIVITY
WILL LIKELY INCREASE IN COVERAGE/INTENSITY THROUGH THE AFTERNOON
WHILE SPREADING EWD. TIME SERIES OF LOCAL PROFILERS AND VWP/S SHOW
A TREND TOWARD WEAKENING LOW-LEVEL SHEAR IN THE AREA WHERE STORMS
ARE FORMING AND WILL MOVE OVER THE NEXT FEW HOURS. THE STRONGER
LOW-LEVEL SHEAR IS LOCATED ALONG THE WARM FRONT IN CENTRAL
MN...WHERE CLOUDS AND COOL SURFACE TEMPERATURES HAVE LIMITED
INSTABILITY. PRESENT INDICATIONS ARE THAT THE COLD FRONTAL STORMS
WILL BE THE PRIMARY CONCERN THROUGH THE AFTERNOON...WITH THE
POSSIBILITY OF DAMAGING WINDS AND LARGE HAIL WITH LINE SEGMENTS
AND/OR SPLITTING SUPERCELLS.

AVIATION...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 27035.

...THOMPSON

+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-
To unsubscribe from WX-STORM send e-mail to LISTSERV@LISTSERV.ILLINOIS.EDU with
"unsub wx-storm" in the body of your message. For more information write cnovy@cox.net.