

056 

WWUS20 KWNS 310138

SEL5

SPC WW 310138

IAZ000-KSZ000-NEZ000-SDZ000-310700-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 405

NWS STORM PREDICTION CENTER NORMAN OK

840 PM CDT MON MAY 30 2011



THE NWS STORM PREDICTION CENTER HAS ISSUED A

SEVERE THUNDERSTORM WATCH FOR PORTIONS OF



       PARTS OF NORTHWEST IOWA

       PARTS OF CENTRAL KANSAS

       MUCH OF EASTERN NEBRASKA

       SMALL PART OF SOUTHEASTERN SOUTH DAKOTA



EFFECTIVE THIS MONDAY NIGHT AND TUESDAY MORNING FROM 840 PM UNTIL

200 AM CDT.



...THIS IS A PARTICULARLY DANGEROUS SITUATION...



EXTREMELY DAMAGING THUNDERSTORM WIND GUSTS TO 90 MPH...LARGE HAIL

TO 1.5 INCHES IN DIAMETER...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 35 MILES NORTHWEST OF

SIOUX CITY IOWA TO 50 MILES SOUTH SOUTHEAST OF RUSSELL KANSAS.

FOR A COMPLETE DEPICTION OF THE WATCH SEE THE ASSOCIATED WATCH

OUTLINE UPDATE (WOUS64 KWNS WOU5).



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 402...WW 403...



DISCUSSION...INTENSE SQUALL LINE HAS DEVELOPED N/S ACROSS CENTRAL

NEB AND CONTINUES TO DEVELOP SWD AS IT MOVES EWD. VERY STRONG PRES

RISE/FALL COUPLET IS DRIVING THE LINE EWD WITH THE FORCING FROM

LARGE SCALE TROUGH ROTATING ACROSS THE NRN/CENTRAL PLAINS PROVIDING

BOTH SHEAR AND UPWARD MOTION TO RESULT IN POTENTIAL FOR VERY

DAMAGING WINDS. IN ADDITION BRIEF TORNADOES ARE STILL POSSIBLE BUT

DAMAGING WINDS NOW ARE THE DOMINANT THREAT.



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

TO 1.5 INCHES. EXTREME TURBULENCE AND SURFACE WIND GUSTS TO 80

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

MOTION VECTOR 23040.





...HALES

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