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URGENT - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Watch Number 345
NWS Storm Prediction Center Norman OK
540 PM CDT Sat Jun 17 2017
The NWS Storm Prediction Center has issued a
* Severe Thunderstorm Watch for portions of
Southern and eastern Iowa
Northern and central Illinois
* Effective this Saturday afternoon and Sunday morning from 540
PM until 100 AM CDT.
* Primary threats include...
Scattered large hail and isolated very large hail events to 2.5
inches in diameter possible
Scattered damaging wind gusts to 70 mph possible
A tornado or two possible
SUMMARY...Storms will continue to intensify generally near a front
where the preceding air mass is most and very unstable. With the aid
of an approaching mid/upper-level system and jet streak, relatively
strong deep-layer winds will help organize storms into
east/southeastward-moving bands through the evening. Damaging winds
and severe hail are the primary concerns.
The severe thunderstorm watch area is approximately along and 60
statute miles north and south of a line from 65 miles west northwest
of Quincy IL to 45 miles east of Marseilles IL. 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
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 600. Mean storm motion vector