Severe Thunderstorms developed rapidly along the
Fremont/Natrona County line around 4 pm. The storms remained nearly stationary
through 5:30 pm, producing large hail and very heavy rain. One inch diameter
hail was reported in Hiland in Northwestern Natrona County at 5:08 pm. Flash
flooding and creeks out of their banks were reported 10 miles north of Lysite
in Northeastern Fremont County at 5:50 pm.
Another line of severe thunderstorms across southeast Natrona
County produced large hail and flash flooding between 5:30 pm and 7:00 pm. One
inch diameter hail was reported 13 miles southwest of Casper at 6:26 pm. Golf
ball size hail was reported on the west side of Casper at 6:15 pm.
Flash Flooding occurred along Highway 220 about 10 miles
southwest of Casper at 6:42 pm. Rocks, boulders, mud, and water covered the
highway. Doppler radar rainfall estimates showed a band of 2 to 3 inches
of rain extending from Alcova Reservoir to an area just southwest of Casper.
Another band of 2 to 3 inch rainfall was noted across northern Natrona County.
The following is the Riverton WSR-88D storm total
precipitation from this storm.

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