

000 

WWUS20 KWNS 270817

SEL4

SPC WW 270817

NDZ000-271500-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 654

NWS STORM PREDICTION CENTER NORMAN OK

315 AM CDT MON AUG 27 2007



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       SOUTHERN AND EASTERN NORTH DAKOTA



EFFECTIVE THIS MONDAY MORNING FROM 315 AM UNTIL 1000 AM 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 50

STATUTE MILES NORTH AND SOUTH OF A LINE FROM 10 MILES SOUTHWEST

OF BISMARCK NORTH DAKOTA TO 15 MILES SOUTH OF FARGO NORTH DAKOTA.

 FOR A COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH

OUTLINE UPDATE (WOUS64 KWNS WOU4).



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...STRONG TSTMS JUST FORMING IN S CNTRL SD EXPECTED TO

INCREASE IN COVERAGE AND POSSIBLY STRENGTH LATER THIS MORNING AS

PASSING UPR JET ENTRANCE REGION IN SRN MB RESULTS IN INCREASING

WAA/ASCENT ABOVE STALLING WSW/ENE-ORIENTED FRONT.  GIVEN DEGREE OF

AVAILABLE CAPE IN UPSTREAM WARM SECTOR /AROUND 3000 J PER

KG/...MODERATE UNIDIRECTIONAL WLY FLOW ABOVE FRONTAL SURFACE...AND

ELY COMPONENT TO NEAR-SURFACE FLOW AHEAD OF STORMS...POTENTIAL WILL

EXIST FOR UPSCALE DEVELOPMENT INTO A N/S BOW MCS.  SUCH A SYSTEM MAY

POSE A THREAT FOR  DAMAGING WIND IN ADDITION TO LARGE HAIL.



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 550. MEAN STORM

MOTION VECTOR 26035.





...CORFIDI

