Heavy Rainfall to Bring Flooding Threat to California; Heavy Snow in the Sierra

A strong atmospheric river will bring heavy rainfall to California through the holiday week. The heaviest rainfall is expected on Wednesday in the Los Angeles Basin. Flash and urban flooding is possible. A prolonged heavy snowfall is expected in the Sierra Nevada from the atmospheric river, raising concerns for major snow‐load impacts. Travel may be difficult to impossible over the passes. Read More >

Overview

Thunderstorms developed near an area of low pressure across central South Dakota during the afternoon on Sunday, July 25th, and quickly intensified to severe limits in a favorable environment after becoming supercells (rotating thunderstorms). Despite temperatures in the 90s and even low 100s, these storms produced large to significantly large hail as they tracked to the east and southeast. By sunset, additional thunderstorms developed across west central Minnesota. One of the more prolific supercells produce hail continuously for ~125 miles from Faulk to Codington Counites over an over 3 hour window of time, of up to nearly 4" in diameter along the way. With 19 reports of severe-criteria hail (at least 1" in diameter) across our forecast area, we more than doubled in our total for the entire season in just one day.

Surface observations at 4pm on July 25, 2021 from the Weather Prediction Center

Photos & Video
Radar, Satellite
Storm Reports

Photos & Video


Quarter to golf ball sized hail on the northeast side of Pierre. Photo courtesy of Mikayla Frick	Large hail from 12 miles south of Faulkton. Photo courtesy of Jason Koester	Large hail from 12 miles south of Faulkton. Photo courtesy of Jason Koester	Large hail from 2 miles north of Ashton. Photo courtesy of Garret Knebel


Large hail at Wallace around 9pm. Photo courtesy of Billie and Monica Moshier, relayed on Twitter via Brent Nathaniel	Roughly 3.75" hail at Wallace around 9pm. Photo courtesy of Billie and Monica Moshier, relayed on Twitter via Brent Nathaniel	Large hail west of South Shore. Photo courtesy of Codington County Emergency Manager	Large hail west of South Shore. Photo courtesy of Codington County Emergency Manager


Cumulonimbus of the large-hail producing storm over Faulk County around 7pm

Radar, Satellite


Radar reflectivity from 4pm to 10pm CDT July 25, 2021


GOES-16 visible satellite imagery from 3pm to 910pm CDT July 25, 2021. From CIRA


24 hour max estimated size of hail, showing the long-track nature of storms	Radar reflectivity at 617pm - southern Hughes County	Radar reflectivity at 740pm - northern Spink County	Radar reflectivity at 900pm - northwestern Codington County