Excessive heat warning and severe risk Wednesday

Heat index 105 to 110, plus an enhanced severe storm risk Wednesday afternoon.

Extreme heat outlook
Extreme heat outlook Wednesday
Twin Cities National Weather Service

Call it peak summer.

Wednesday brings one of the hottest and most humid days of the year to Minnesota. High temperatures will soar into the mid and upper 90s across southern Minnesota Wednesday afternoon. Throw in dew points above 70 degrees and you’ve got heat index values between 105 and 110 degrees across southern Minnesota.

That level of heat index meets the criteria for an excessive heat warning from the Twin Cities NWS office Wednesday.

Excessive heat warning Wednesday
Excessive heat warning Wednesday
Twin Cities National Weather Service

Including the cities of Minneapolis, Blaine, St Paul, Stillwater, Chanhassen, Chaska, Victoria, Shakopee, and Hastings

336 PM CDT Tue Jul 27 2021

...HEAT ADVISORY REMAINS IN EFFECT UNTIL 9 PM CDT THIS EVENING...

...EXCESSIVE HEAT WARNING IN EFFECT FROM 9 PM THIS EVENING TO 9 PM CDT WEDNESDAY...

* WHAT...For the Excessive Heat Warning, warm overnight, and then dangerously hot conditions Wednesday with heat index values up to 105 expected. For the Heat Advisory, heat index values up to 101.

* WHERE...Hennepin, Anoka, Ramsey, Washington, Carver, Scott and Dakota Counties.

* WHEN...For the Excessive Heat Warning, from 9 PM this evening to 9 PM CDT Wednesday. For the Heat Advisory, until 9 PM CDT this evening.

* IMPACTS...Potential for heat-related illnesses, particularly for those working or participating in outdoor activities.

* ADDITIONAL DETAILS...Low temperatures in the low to mid 70s overnight will allow for little relief from the heat overnight, with the warmest conditions expected Wednesday afternoon.

Enhanced severe risk

Short range forecast models suggest a few isolated thunderstorms are possible early Wednesday morning, then a low-pressure system and cool front will sag south through Minnesota Wednesday evening. As it cuts into our steamy tropical air mass, thunderstorms are likely to bloom in the late afternoon and evening hours.

NOAA’s NAM 3 km resolution model develops a line of thunderstorms just north of the Twin Cities eastward into Wisconsin around 6 p.m. Wednesday. The line pushes south through Wednesday night.

NOAA’s Storm Prediction Center paints an enhanced risk for severe storms from near the Twin Cities southeastward into Wisconsin. Slight and marginal risk zones surround that area.

Severe weather risk zone Wednesday
Severe weather risk areas Wednesday
NOAA/Twin Cities National Weather Service

It looks like it may be a close call for severe weather in the Twin Cities late Wednesday. Some forecast models keep the bulk of storms just east of the Twin Cities into Wisconsin. We’ll have to watch precisely where storms develop Wednesday afternoon.

A much more pleasant and comfortable air mass blows into all of Minnesota starting Thursday and lasting through the upcoming weekend.

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