

549 

WWUS20 KWNS 011919

SEL3

SPC WW 011919

NDZ000-SDZ000-020300-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 713

NWS STORM PREDICTION CENTER NORMAN OK

120 PM MDT MON AUG 1 2011



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       WESTERN AND CENTRAL NORTH DAKOTA

       NORTHWEST AND NORTH-CENTRAL SOUTH DAKOTA



EFFECTIVE THIS MONDAY AFTERNOON AND EVENING FROM 120 PM UNTIL 900

PM MDT.



HAIL TO 2.5 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 110 MILES SOUTH

SOUTHWEST OF LEMMON SOUTH DAKOTA TO 35 MILES EAST NORTHEAST OF

GARRISON NORTH 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.



OTHER WATCH INFORMATION...CONTINUE...WW 709...WW 710...WW

711...WW 712...



DISCUSSION...TSTMS ARE RAPIDLY INCREASINGLY ALONG COLD FRONT THIS

AFTERNOON IN RESPONSE TO APPROACH OF WELL-DEFINED SHORT WAVE TROUGH

THROUGH WY.  AMBIENT WARM SECTOR IS CHARACTERIZED BY STEEP LAPSE

RATES AND A MOIST BOUNDARY LAYER WITH MLCAPE UPWARDS OF 3000-4000

J/KG.  WHEN COUPLED WITH STEADILY STRENGTHENING DEEP-LAYER

SHEAR...ENVIRONMENT WILL SUPPORT SUPERCELLS AND BOWING STRUCTURES

CAPABLE OF MAINLY LARGE HAIL AND DAMAGING WINDS.



AVIATION...A FEW SEVERE THUNDERSTORMS WITH HAIL SURFACE AND ALOFT

TO 2.5 INCHES. EXTREME TURBULENCE AND SURFACE WIND GUSTS TO 60

KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO 550. MEAN STORM

MOTION VECTOR 27025.





...MEAD

