

375 

WWUS20 KWNS 060031

SEL1

SPC WW 060031

NDZ000-SDZ000-060700-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 731

NWS STORM PREDICTION CENTER NORMAN OK

730 PM CDT FRI AUG 5 2011



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       CENTRAL AND EASTERN NORTH DAKOTA

       CENTRAL AND NORTHEAST SOUTH DAKOTA



EFFECTIVE THIS FRIDAY NIGHT AND SATURDAY MORNING FROM 730 PM

UNTIL 200 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 60

STATUTE MILES EAST AND WEST OF A LINE FROM 40 MILES NORTHEAST OF

JAMESTOWN NORTH DAKOTA TO 30 MILES SOUTHEAST OF PIERRE SOUTH

DAKOTA.  FOR A COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED

WATCH OUTLINE UPDATE (WOUS64 KWNS WOU1).



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.



OTHER WATCH INFORMATION...CONTINUE...WW 729...WW 730...



DISCUSSION...LINE OF STRONG/SEVERE STORMS FROM SOUTH CENTRAL ND INTO

SWRN SD IS EXPECTED TO PROGRESS EWD IN ADVANCE OF AN UPPER TROUGH

MOVING EWD TOWARD THE NRN PLAINS.  00Z RAOBS AT BIS/RAP/ABR INDICATE

STEEP MID LEVEL LAPSE RATES ATOP A GENERALLY MOIST BOUNDARY LAYER

WITH CAPE OF 1500-3000 J/KG AHEAD OF THE CONVECTIVE LINE.  WINDS

ALOFT ARE INCREASING FROM THE WEST IN ASSOCIATION WITH THE ADVANCING

UPPER TROUGH...WITH 30-40 KT OF DEEP LAYER SHEAR OVER THE AREA.

THREAT FOR SEVERE STORMS WITH STRONG WIND GUSTS AND OCCASIONAL HAIL

WILL CONTINUE DURING THE NEXT FEW HOURS.



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 25025.





...WEISS

