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WWUS20 KWNS 311639

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SPC WW 311639

IAZ000-MOZ000-NEZ000-SDZ000-010000-



URGENT - IMMEDIATE BROADCAST REQUESTED

TORNADO WATCH NUMBER 100

NWS STORM PREDICTION CENTER NORMAN OK

1140 AM CDT SAT MAR 31 2007



THE NWS STORM PREDICTION CENTER HAS ISSUED A

TORNADO WATCH FOR PORTIONS OF



       MUCH OF CENTRAL AND WESTERN IOWA

       PARTS OF NORTHERN MISSOURI

       PARTS OF EASTERN NEBRASKA

       SMALL PART OF SOUTHEASTERN SOUTH DAKOTA



EFFECTIVE THIS SATURDAY MORNING AND EVENING FROM 1140 AM UNTIL

700 PM CDT.



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 90 STATUTE

MILES EAST AND WEST OF A LINE FROM 25 MILES NORTHWEST OF SPENCER

IOWA TO 40 MILES SOUTHWEST OF LAMONI IOWA.  FOR A COMPLETE

DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH OUTLINE UPDATE

(WOUS64 KWNS WOU0).



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 99...



DISCUSSION...VIGOROUS S/WV TROUGH AND DEEPENING SURFACE LOW WILL

TRACK NEWD ACROSS WATCH AREA THIS AFTERNOON.  AHEAD OF THE SURFACE

LOW SHEAR AND INSTABILITY WILL SUPPORT SUPERCELLS INCLUDING A

TORNADO AND LARGE HAIL THREAT.  INITIAL STORMS FORMING ON COLD FRONT

SERN NE WITH ADDITIONAL STORMS EVENTUALLY IN WARM SECTOR NWD TO WARM

FRONT WHICH WILL BE SHIFTING NWD THRU IS AHEAD OF LOW AND S/WV

TROUGH.



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

450. MEAN STORM MOTION VECTOR 21035.





...HALES

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