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URGENT - IMMEDIATE BROADCAST REQUESTED
Severe Thunderstorm Watch Number 643
NWS Storm Prediction Center Norman OK
835 PM CDT Tue Sep 10 2019
The NWS Storm Prediction Center has issued a
* Severe Thunderstorm Watch for portions of
Southeast South Dakota
* Effective this Tuesday night and Wednesday morning from 835 PM
until 400 AM CDT.
* Primary threats include...
Scattered damaging winds and isolated significant gusts to 75
Scattered large hail and isolated very large hail events to 2
inches in diameter possible
A tornado or two possible
SUMMARY...Clusters of storms will continue to merge and grow upscale
into a larger convective system that will spread eastward overnight
with an attendant threat for damaging winds and large hail. In the
short term, a supercell moving into Bon Homme County South Dakota
will pose a threat for a tornado or two before being overtaken and
merging with the clusters to the west.
The severe thunderstorm watch area is approximately along and 45
statute miles north and south of a line from 35 miles northwest of
Oneill NE to 20 miles north northeast of Spencer IA. For a complete
depiction of the watch see the associated watch outline update
(WOUS64 KWNS WOU3).
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
OTHER WATCH INFORMATION...This severe thunderstorm watch replaces
severe thunderstorm watch number 642. Watch number 642 will not
be in effect after 835 PM CDT. CONTINUE...WW 640...WW 641...
AVIATION...A few severe thunderstorms with hail surface and aloft to
2 inches. Extreme turbulence and surface wind gusts to 65 knots. A
few cumulonimbi with maximum tops to 550. Mean storm motion vector