

350 

WWUS20 KWNS 240203

SEL3

SPC WW 240203

MTZ000-NDZ000-SDZ000-240700-



URGENT - IMMEDIATE BROADCAST REQUESTED

TORNADO WATCH NUMBER 733

NWS STORM PREDICTION CENTER NORMAN OK

755 PM MDT SUN AUG 23 2009



THE NWS STORM PREDICTION CENTER HAS ISSUED A

TORNADO WATCH FOR PORTIONS OF



       EASTERN MONTANA

       WESTERN NORTH DAKOTA

       NORTHWEST SOUTH DAKOTA



EFFECTIVE THIS SUNDAY NIGHT AND MONDAY MORNING FROM 755 PM UNTIL

100 AM MDT.



TORNADOES...HAIL TO 2 INCHES IN DIAMETER...THUNDERSTORM WIND

GUSTS TO 70 MPH...AND DANGEROUS LIGHTNING ARE POSSIBLE IN THESE

AREAS.



THE TORNADO WATCH AREA IS APPROXIMATELY ALONG AND 105 STATUTE

MILES EAST AND WEST OF A LINE FROM 60 MILES NORTH NORTHWEST OF

WILLISTON NORTH DAKOTA TO 30 MILES SOUTHWEST OF LEMMON SOUTH

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

WATCH OUTLINE UPDATE (WOUS64 KWNS WOU3).



REMEMBER...A TORNADO WATCH MEANS CONDITIONS ARE FAVORABLE FOR

TORNADOES AND 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.



OTHER WATCH INFORMATION...CONTINUE...WW 732...



DISCUSSION...TSTMS/SUPERCELLS EXPECTED TO INCREASE/DEVELOP OVER WW

AREA THROUGH EARLY MON...IN ZONE OF INCREASING LOW LVL WAA/UPR

DIVERGENCE DOWNSTREAM FROM SHORTWAVE IMPULSE NOW ENTERING WRN WY.

STORMS NOW OVER NE MT LIKELY ARE HIGH BASED.  THESE SHOULD DEVELOP

DOWNWARD WITH TIME AS THEY ENCOUNTER MOISTENING ELY LOW LVL FLOW N

OF SE MT SFC LOW.  OTHER STORMS...LIKELY MORE NEARLY

SFC-BASED...SHOULD FORM SWD AND EWD INTO WRN ND...IN REGION OF

GREATER LOW LVL SPEED/ DIRECTIONAL SHEAR.  WHILE LOW LVL CIN WILL BE

A FACTOR OPPOSING A WIDESPREAD TORNADIC THREAT...ABSENCE OF STRONG

LOW LVL LINEAR FORCING AND ENLARGED LOW LVL HODOGRAPHS WITH

STRENGTHENING LLJ SUGGESTS POTENTIAL FOR ISOLD TORNADOES LATER THIS

EVE/EARLY MON...IN ADDITION TO SVR HAIL AND WIND.



AVIATION...TORNADOES AND 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 24030.





...CORFIDI

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