Strong storms parts of Minn. Friday evening and overnight; steamy Saturday

I’ll get to the weekend forecast shortly, but you should also know about the potential for some strong or severe thunderstorms Friday evening and overnight Friday night.

A few spotty thunderstorms could pop up in Minnesota and western Wisconsin Friday afternoon. More significant areas of thunderstorms are expected to develop in northwestern and west-central Minnesota Friday evening and spread to cover much of Minnesota and western Wisconsin as we go through the overnight hours of Friday night.

That main batch of thunderstorms probably won’t arrive in Twin Cities until sometime after midnight.

Forecast models are showing varied thunderstorm coverage overnight Friday night. The National Oceanic and Atmospheric Administration’s North American Mesoscale forecast model shows the potential rain pattern Friday evening and through the overnight hours of Friday night:

NOAA’s High-Resolution Rapid Refresh forecast model doesn’t spread the thunderstorms as far southward:

We’ll see if the afternoon runs of the forecast models show more agreement.

You can hear updated weather information on the MPR network, and you’ll see updated weather info on the MPR News live weather blog.

Severe weather outlook

Northern Minnesota and parts of central Minnesota have the best chance of severe weather Friday evening and overnight.

The National Weather Service Storm Prediction Center’s severe weather outlook for Friday and Friday night has a moderate risk (shaded red) and enhanced risk (shaded beige) for those areas:

Here are the severe weather categories that are used by the SPC:

This is a closer look at the severe weather potential, from the Grand Forks, N.D., NWS office:

Make sure that you have a way to receive severe weather warnings this evening and overnight.

Saturday thunderstorm chances

A few scattered thunderstorms could linger over portions of eastern Minnesota and western Wisconsin early Saturday morning.

Scattered thunderstorms could also develop over parts of central Minnesota late Saturday afternoon and spread southward and eastward Saturday evening.

The National Weather Service Storm Prediction Center shows a slight risk of severe weather in those areas Saturday and Saturday night, with our main chance of severe weather Saturday evening and overnight Saturday night:

Steamy Saturday, better on Sunday

Saturday highs reach the 90s in the southern half of Minnesota and most of western Wisconsin:

Saturday afternoon dew points will be in the steamy 70s in many locations:

Heat index values will be well above 100 in many areas Saturday afternoon, including the Twin Cities. An excessive heat watch runs from 11 a.m. to 9 p.m. Saturday in the Twin Cities, southern Minnesota and west-central Wisconsin:

Southeastern Minnesota has a heat advisory for Saturday afternoon/early evening.

Here are details of the excessive heat watch:

URGENT - WEATHER MESSAGE National Weather Service Twin Cities/Chanhassen MN 238 AM CDT Fri Jul 17 2020 MNZ051>053-059>063-066>070-074>078-082>085-091>093-171545- /O.CON.KMPX.EH.A.0001.200718T1600Z-200719T0200Z/ Sherburne-Isanti-Chisago-Wright-Hennepin-Anoka-Ramsey-Washington- McLeod-Sibley-Carver-Scott-Dakota-Brown-Nicollet-Le Sueur-Rice- Goodhue-Watonwan-Blue Earth-Waseca-Steele-Martin-Faribault- Freeborn- Including the cities of Elk River, Cambridge, Center City, Monticello, Minneapolis, Blaine, St Paul, Stillwater, Hutchinson, Gaylord, Chanhassen, Chaska, Victoria, Shakopee, Hastings, New Ulm, St Peter, Le Sueur, Faribault, Red Wing, St James, Mankato, Waseca, Owatonna, Fairmont, Blue Earth, and Albert Lea 238 AM CDT Fri Jul 17 2020 ...EXCESSIVE HEAT WATCH REMAINS IN EFFECT FROM SATURDAY MORNING THROUGH SATURDAY EVENING... * WHAT...Dangerously hot conditions with heat index values up to 108 possible. * WHERE...Portions of central, east central, south central and southeast Minnesota. * WHEN...From Saturday morning through Saturday evening. * IMPACTS...Extreme heat and humidity will significantly increase the potential for heat related illnesses, particularly for those working or participating in outdoor activities. PRECAUTIONARY/PREPAREDNESS ACTIONS... Monitor the latest forecasts and warnings for updates on this situation. Be prepared to drink plenty of fluids, stay in an air- conditioned room, stay out of the sun, and check up on relatives and neighbors. Young children and pets should never be left unattended in vehicles under any circumstances. This is especially true during warm or hot weather when car interiors can reach lethal temperatures in a matter of minutes.

Sunday will be cooler and much less humid.

Sunday highs will be mainly in the 80s, with some 70s in far northern Minnesota:

Dew points retreat to the 60s, with some very dry (for July) 50s to the north:

I hope that you have a great weekend!

Programming note

You can hear my live weather updates on MPR News at 7:35 a.m., 9:35 a.m. and 4:35 p.m. each Saturday and Sunday.