The National Weather Service has issued a Severe Thunderstorm Warning and Flood Advisory for Boulder County. Sign up to receive emergency alerts at www.boco911alert.com

The Flood Advisory impacts will include small stream flooding and flooding of low lying areas and areas with low drainage in Boulder, Longmont, Lafayette, Louisville, Superior, Niwot, and Hygiene.

Severe Thunderstorm Warning impacts include quarter-sized hail and wind gusts up to 60 mph in Boulder, Louisville, Lafayette, Erie, and Niwot.

Avoid underpasses. With the potential for flooding, underpasses are not a safe place to seek shelter. If you need to seek shelter in the Civic Area, the lobby of the Penfield Tate II Municipal Building at 1777 Broadway is open.

Goose Creek, S. Boulder Creek and Bear Creek are overflowing, and the underpasses and low-lying crossings are completely flooded over. Please avoid.

Follow @NWSBoulder for weather updates and @ColoradoDOT on Twitter for highway closures.

Sign up to receive emergency alerts at www.bocoalert.com.

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