

000 

WWUS20 KWNS 301807

SEL8

SPC WW 301807

IAZ000-NEZ000-SDZ000-010100-



URGENT - IMMEDIATE BROADCAST REQUESTED

TORNADO WATCH NUMBER 698

NWS STORM PREDICTION CENTER NORMAN OK

105 PM CDT SUN SEP 30 2007



THE NWS STORM PREDICTION CENTER HAS ISSUED A

TORNADO WATCH FOR PORTIONS OF



       WESTERN IOWA

       EASTERN NEBRASKA

       EXTREME SOUTHEAST SOUTH DAKOTA



EFFECTIVE THIS SUNDAY AFTERNOON AND EVENING FROM 105 PM UNTIL 800

PM CDT.



TORNADOES...HAIL TO 1.5 INCHES IN DIAMETER...THUNDERSTORM WIND

GUSTS TO 80 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 15 MILES SOUTH SOUTHWEST OF

BEATRICE NEBRASKA TO 20 MILES NORTH OF SPENCER IOWA.  FOR A

COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH OUTLINE

UPDATE (WOUS64 KWNS WOU8).



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 697...



DISCUSSION...POTENT MID-LEVEL DISTURBANCE AND ASSOCIATED DEVELOPING

SURFACE LOW OVER NEBRASKA WILL DEVELOP ENEWD ACROSS THE MISSOURI

RIVER VALLEY TO NWRN/CNTRL IA THROUGH THE AFTERNOON/EARLY EVENING.

DESPITE ONLY WEAK DESTABILIZATION...INCREASINGLY STRONG DYNAMIC

FORCING FOR ASCENT AND INTENSE WIND FIELDS AND SHEAR ARE EXPECTED TO

SUPPORT THE DEVELOPMENT OF STRONG TO SEVERE STORMS/SUPERCELLS. GIVEN

STRENGTH OF EFFECTIVE SHEAR AND LOW LEVEL HODOGRAPH TURNING WITHIN

AND NEAR THE DEVELOPING LOW...A FEW TORNADOES ARE

POSSIBLE...ESPECIALLY EARLY IN THE DEVELOPMENT CYCLE. FAST

TRANSLATION TO THE ENTIRE LAGER-SCALE SYSTEM SHOULD PROMOTE

BAND/LINES OF STORMS WITH TIME. THIS ACTIVITY WILL RACE EWD WITH

DAMAGING WINDS AND ISOLATED TORNADO POTENTIAL SPREADING INTO CNTRL

IA BY EARLY EVENING.



AVIATION...TORNADOES AND A FEW SEVERE THUNDERSTORMS WITH HAIL

SURFACE AND ALOFT TO 1.5 INCHES. EXTREME TURBULENCE AND SURFACE

WIND GUSTS TO 70 KNOTS. A FEW CUMULONIMBI WITH MAXIMUM TOPS TO

450. MEAN STORM MOTION VECTOR 23045.





...CARBIN

