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WWUS20 KWNS 040124

SEL7

SPC WW 040124

IAZ000-MOZ000-NEZ000-041000-



URGENT - IMMEDIATE BROADCAST REQUESTED

SEVERE THUNDERSTORM WATCH NUMBER 537

NWS STORM PREDICTION CENTER NORMAN OK

820 PM CDT THU OCT 3 2013



THE NWS STORM PREDICTION CENTER HAS ISSUED A



* SEVERE THUNDERSTORM WATCH FOR PORTIONS OF

  SOUTHERN AND CENTRAL IOWA

  NORTHERN MISSOURI

  EASTERN NEBRASKA



* EFFECTIVE THIS THURSDAY NIGHT AND FRIDAY MORNING FROM 820 PM

  UNTIL 500 AM CDT.



* PRIMARY THREATS INCLUDE...

  NUMEROUS LARGE HAIL EVENTS LIKELY WITH A FEW VERY LARGE HAIL

    EVENTS TO 2.5 INCHES IN DIAMETER POSSIBLE

  SEVERAL DAMAGING WIND GUSTS TO 70 MPH POSSIBLE

  A FEW TORNADOES POSSIBLE



THE SEVERE THUNDERSTORM WATCH AREA IS APPROXIMATELY ALONG AND 140

STATUTE MILES EAST AND WEST OF A LINE FROM 10 MILES WEST

SOUTHWEST OF FALLS CITY NEBRASKA TO 70 MILES NORTH OF DES MOINES

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

WATCH OUTLINE UPDATE (WOUS64 KWNS WOU7).



PRECAUTIONARY/PREPAREDNESS ACTIONS...



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 JUST NOW FORMING IN SE NEB EXPECTED TO INCREASE

IN COVERAGE AND INTENSITY ALONG AND N OF SLOWLY-MOVING SW-NE COLD

FRONT...AND ALONG AND N OF DIFFUSE OUTFLOW BOUNDARY EXTENDING ESE

FROM FRONT INTO N CNTRL MO. UPLIFT IN THESE AREAS WILL BE FOCUSED BY

NOCTURNALLY-STRENGTHENED SSWLY LLJ /WITH SPEEDS EXPECTED TO REACH

45-50 KTS/.

THE STORMS SHOULD PERSIST THROUGH EARLY FRI AND LIKELY WILL EVOLVE

INTO A SIZABLE MCS. WHILE THE MAIN SVR THREAT DURING THE DURATION OF

THE WATCH SHOULD BE LARGE HAIL...A NON-ZERO TORNADO POTENTIAL ALSO

WILL EXIST. THIS THREAT SHOULD BE GREATEST OVER THE NEXT 2-3 HOURS

OVER ERN NEB...WHERE LOW-LVL DIRECTIONAL SHEAR WILL BE MAXIMIZED

BETWEEN COLD FRONT AND WEAKENING OUTFLOW BOUNDARY /REF MCD 1924 AND

01Z CONVECTIVE OUTLOOK/.



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

TO 2.5 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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