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WWUS20 KWNS 242220

SEL8

SPC WW 242220

NDZ000-250600-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 588

NWS STORM PREDICTION CENTER NORMAN OK

520 PM CDT FRI AUG 24 2012



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       CENTRAL NORTH DAKOTA



EFFECTIVE THIS FRIDAY AFTERNOON AND SATURDAY MORNING FROM 520 PM

UNTIL 100 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 75

STATUTE MILES EAST AND WEST OF A LINE FROM 65 MILES SOUTH

SOUTHEAST OF BISMARCK NORTH DAKOTA TO 55 MILES EAST NORTHEAST OF

MINOT NORTH DAKOTA.  FOR A COMPLETE DEPICTION OF THE WATCH SEE

THE ASSOCIATED WATCH OUTLINE UPDATE (WOUS64 KWNS WOU8).



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...TSTMS HAVE RECENTLY DEVELOPED AHEAD OF COLD FRONT AND

MIGRATORY SURFACE LOW IN RESPONSE TO INCREASING FORCING FOR ASCENT

ASSOCIATED WITH SHORTWAVE TROUGH MOVING THROUGH THE NRN HIGH PLAINS.

CURRENT SURFACE OBSERVATIONS INDICATE THAT WARM SECTOR IS SLIGHTLY

MORE MOIST THAN SOME MODEL GUIDANCE WITH MLCAPE OF AROUND 1000 J/KG

ESTIMATED.  WHEN COUPLED WITH STEEP LOW TO MIDLEVEL LAPSE RATES...A

DEEP...WELL-MIXED SUB-CLOUD LAYER AND 40-50 KT OF DEEP LAYER

SHEAR...SETUP WILL PROMOTE A MIX OF SUPERCELLS AND BOWING STRUCTURES

CAPABLE DAMAGING WINDS AND 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 500. MEAN STORM

MOTION VECTOR 23025.





...MEAD

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