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Erin Strengthens to a Hurricane; Heavy Rainfall Possible in Puerto Rico and the Virgin Islands, the Upper Midwest, South Texas

Hurricane Erin may bring isolated flash and urban flooding, landslides or mudslides, and possible tropical storm conditions to Puerto Rico and the U.S. Virgin Islands this weekend. Scattered thunderstorms and heavy rainfall may bring areas of flooding this weekend over the Upper Midwest. A tropical disturbance will bring locally heavy rain and mainly urban flash flooding to far southern Texas. Read More >

Overview

Severe storms with large hail and damaging winds occurred on July 11, 2023 over parts of northeastern Wyoming and western South Dakota. A swath of large hail, up to baseball size, moved through northern Campbell and Crook Counties, causing major damage to structures and vehicles. Other areas of northeastern Wyoming, the Black Hills, and the western South Dakota plains were hit with tennis ball sized hail. Along with the destructive hail, several strong and damaging wind reports occurred as the severe thunderstorms moved across the region. This highest wind gust reported was 71 MPH near Ludlow, SD.

As can be seen in the lightning map to the right (click to enlarge), thunderstorms occurred across a large portion of northeast Wyoming, western South Dakota and south-central South Dakota. Positive cloud-to-ground flashes were especially notable from northern Campbell county through the Black Hills, and from northwestern South Dakota through south central South Dakota, where areas of heavier rain and larger hail occurred.

Here is the 24-hour cloud-to-ground lightning map from 6 am MDT Tuesday (7/11) to 6 am MDT Wednesday (7/12). Red plus signs indicate positive polarity flashes and green dashes indicate negative polarity flashes. Total flash counts in upper right.

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