WATCHES: Severe Thunderstorm Watch Number 537

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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