Heat returns this week; Triple-digit highs in some places Tuesday & Wednesday

Sunday afternoon temperatures and dew points will be be comfortable across much of Minnesota and western Wisconsin.

• Highs will reach the 80s across roughly the southern half of Minnesota and into west-central Wisconsin. A few spots in far southeastern Minnesota could touch 90.

• Most of northern Minnesota will have Sunday highs in the 70s, with a few 60s in parts of northwestern Minnesota.

• Northwestern and north-central Minnesota could see a few scattered showers at times Sunday afternoon and early Sunday evening.

You can hear updated weather information for Minnesota and western Wisconsin on the MPR News network.

Air quality

Air quality in Minnesota is forecast to be mainly in the moderate category this Sunday. Smoke from Canadian wildfires is mainly aloft, but some of the smoke has mixed down to the surface.

Hazy skies are expected in many areas today due to the smoke layer. The Minnesota Pollution Control Agency updates Minnesota air quality readings each hour.

Heat returns this week

An unusually warm upper-level ridge will build northward Monday into Wednesday, so hot temperatures will spread to include more of Minnesota each day.

Monday highs will range from 90s in southwestern and south-central Minnesota to 60s in far northern Minnesota:

Twin Cities metro area highs will be mainly in the upper 80s on Monday, but a few spots in the metro could touch 90.

Tuesday highs reach triple-digits in southwestern and south-central Minnesota, as 90s expand through central Minnesota:

Twin Cities metro area highs will probably reach the upper 90s on Tuesday.

Wednesday high temperatures are forecast to reach triple-digits in roughly the southern third of Minnesota, including the Twin Cities:

The Twin Cities record highs for Aug. 22 (Tuesday) and Aug. 23 (Wednesday) are 97 degrees. One or both of those daily high temperature records could be broken. Stayed tuned for updates.

Twin Cities metro area highs are projected to reach the mid 90s on Thursday, followed by mid 80s Friday.

Excessive heat watch

The National Weather Service has posted an excessive heat watch for roughly the southern third of Minnesota, plus several western Wisconsin counties, from noon Tuesday to 7 p.m. Thursday:

Here are details of the excessive heat watch:

URGENT - WEATHER MESSAGE National Weather Service Twin Cities/Chanhassen MN 306 AM CDT Sun Aug 20 2023 MNZ054-056-059>070-075>078-085-WIZ023-024-026-201800- /O.EXB.KMPX.EH.A.0001.230822T1700Z-230825T0000Z/ Lac Qui Parle-Chippewa-Wright-Hennepin-Anoka-Ramsey-Washington- Yellow Medicine-Renville-McLeod-Sibley-Carver-Scott-Dakota- Nicollet-Le Sueur-Rice-Goodhue-Steele-St. Croix-Pierce-Pepin- Including the cities of Madison, Montevideo, Monticello, Minneapolis, Blaine, St Paul, Stillwater, Granite Falls, Olivia, Hutchinson, Gaylord, Chanhassen, Chaska, Victoria, Shakopee, Hastings, St Peter, Le Sueur, Faribault, Red Wing, Owatonna, Hudson, River Falls, and Durand 306 AM CDT Sun Aug 20 2023 ...EXCESSIVE HEAT WATCH IN EFFECT FROM TUESDAY AFTERNOON THROUGH THURSDAY EVENING... * WHAT...Dangerously hot conditions with heat index values up to 110 possible. * WHERE...Portions of central, east central, south central, southeast and west central Minnesota and west central Wisconsin. * WHEN...From Tuesday afternoon through Thursday evening. * IMPACTS...Extreme heat and humidity will significantly increase the potential for heat related illnesses, particularly for those working or participating in outdoor activities. * ADDITIONAL DETAILS...The hottest day looks to be Wednesday but that still may vary among Tuesday through Thursday. In addition, overnight temperatures will only drop to the lower to middle 70s, providing little relief from the effects of the heat during the nighttime periods. 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.

The excessive heat watch begins Monday afternoon in parts of southwestern Minnesota.

Monday rain chance

Roughly the northern third of Minnesota has a chance of showers on Monday. The National Oceanic and Atmospheric Administration’s High Resolution Rapid refresh (HRRR) forecast model shows the potential rain pattern from 4 a.m. Monday to 10 p.m. Monday:

You can check these National Weather Service sites for updated weather info: Twin Cities, Duluth, La Crosse, Wis., Sioux Falls, S.D., and Grand Forks, N.D.

 Also check out the MPR News display of National Weather Service radar.

Tropical Storm Hilary

Hilary weakened to tropical storm strength Sunday morning and is no longer a hurricane.

Here’s the forecast track, plus the cone of uncertainty, for the center of Hilary:

Here are potential rainfall totals for Sunday into Monday:

Yellow-shaded areas are between 4 and 6 inches of additional rain, with 6 to 10 inches of additional rain possible in the orange-shaded areas.

Hilary’s flooding rains are a huge problem. Here’s an excerpt from the latest Hilary advisory issued by the NWS National Hurricane Center:

Hilary is expected to produce storm total rainfall amounts of 3 to 6 inches, with maximum amounts up to 10 inches, across portions of the northern Baja California Peninsula through tonight. Flash and urban flooding, locally catastrophic, is expected. Intense heavy rainfall associated with Hilary is expected across the Southwestern United States through early Monday morning. Rainfall amounts of 3 to 6 inches, with isolated maximum amounts of 10 inches, are expected across portions of southern California and southern Nevada leading to dangerous to catastrophic flooding.

This is the complete Sunday morning Hilary update from the NWS National Hurricane Center:

BULLETIN Tropical Storm Hilary Advisory Number 17 NWS National Hurricane Center Miami FL EP092023 800 AM PDT Sun Aug 20 2023 ...HILARY VERY NEAR THE WEST COAST OF BAJA CALIFORNIA... ...CATASTROPHIC AND LIFE-THREATENING FLOODING LIKELY OVER BAJA CALIFORNIA AND PORTIONS OF THE SOUTHWESTERN U.S. THROUGH MONDAY... SUMMARY OF 800 AM PDT...1500 UTC...INFORMATION ---------------------------------------------- LOCATION...29.7N 115.9W ABOUT 220 MI...350 KM SSE OF SAN DIEGO CALIFORNIA MAXIMUM SUSTAINED WINDS...70 MPH...110 KM/H PRESENT MOVEMENT...NNW OR 345 DEGREES AT 25 MPH...41 KM/H MINIMUM CENTRAL PRESSURE...984 MB...29.06 INCHES WATCHES AND WARNINGS -------------------- CHANGES WITH THIS ADVISORY: The government of Mexico has discontinued the Hurricane Watch and downgraded the Hurricane Warning to a Tropical Storm Warning for the Baja California Peninsula. The government of Mexico has discontinued the Tropical Storm Warning south of Puerto San Andresito on the west coast and south of Loreto on the east coast of the Baja California Peninsula. SUMMARY OF WATCHES AND WARNINGS IN EFFECT: A Tropical Storm Warning is in effect for... * Baja California peninsula west coast from Puerto San Andresito northward * Baja California peninsula east coast from Loreto northward * Mainland Mexico north of Guaymas * California/Mexico border to Point Mugu * Catalina Island A Tropical Storm Warning means that tropical storm conditions are expected somewhere within the warning. Interests elsewhere in the southwestern U.S. should monitor the progress of Hilary. For storm information specific to your area in the United States, including possible inland watches and warnings, please monitor products issued by your local National Weather Service forecast office. For storm information specific to your area outside of the United States, please monitor products issued by your national meteorological service. DISCUSSION AND OUTLOOK ---------------------- At 800 AM PDT (1500 UTC), the center of Tropical Storm Hilary was located near latitude 29.7 North, longitude 115.9 West. Hilary is moving quickly toward the north-northwest near 25 mph (41 km/h). Hilary is expected to accelerate even more as it moves north-northwestward to northward during the next day or so. On the forecast track, the center of Hilary will move near or over the northern portion of the Baja California Peninsula during the next few hours, and then move across southern California this afternoon. Maximum sustained winds are near 70 mph (110 km/h) with higher gusts. Weakening is expected, but Hilary is expected to remain a tropical storm before it reaches southern California. Tropical-storm-force winds extend outward up to 240 miles (390 km) from the center. The estimated minimum central pressure is 984 mb (29.06 inches). HAZARDS AFFECTING LAND ---------------------- Key messages for Hilary can be found in the Tropical Cyclone Discussion under AWIPS header MIATCDEP4 and WMO header WTPZ44 KNHC and on the web at hurricanes.gov/text/MIATCDEP4.shtml. RAINFALL: Hilary is expected to produce storm total rainfall amounts of 3 to 6 inches, with maximum amounts up to 10 inches, across portions of the northern Baja California Peninsula through tonight. Flash and urban flooding, locally catastrophic, is expected. Intense heavy rainfall associated with Hilary is expected across the Southwestern United States through early Monday morning. Rainfall amounts of 3 to 6 inches, with isolated maximum amounts of 10 inches, are expected across portions of southern California and southern Nevada leading to dangerous to catastrophic flooding. Across portions of Oregon and Idaho, rainfall totals of 1 to 3 inches with local maxima to 5 inches are expected through Tuesday morning, resulting in localized, some significant, flash flooding. A list of rainfall observations compiled by the NOAA Weather Prediction Center for this storm can be found at: www.wpc.ncep.noaa.gov/discussions/nfdscc4.html WIND: Tropical storm conditions are occurring within the tropical storm warning area within the Baja California Peninsula and will continue through today. Tropical storm conditions are expected to begin in southern California this afternoon. Winds could be particularly strong and gusty in and near areas of elevated terrain. Higher gusts are expected well inland and will persist even after the system becomes post-tropical. STORM SURGE: A dangerous storm surge is likely to produce coastal flooding along the western Baja California peninsula of Mexico near where the center passes the coast in areas of onshore winds, or east of the center if Hilary makes landfall. The surge will be accompanied by large and destructive waves. Coastal flooding is possible along the northern coast of the Gulf of California today through early Monday. TORNADOES: A couple tornadoes are possible through this evening over southeast California, western Arizona, southern Nevada, and far southwest Utah. SURF: Large swells generated by Hilary will affect portions of the Baja California Peninsula and southern California over the next day or so. These swells are likely to cause life-threatening surf and rip current conditions. Please consult products from your local weather office.

The National Hurricane Center will issue updates on Hilary every three hours or so.

Programming note

You can hear my live weather updates on MPR News at 7:35 a.m., 9:35 a.m. and 4:39 p.m. each Saturday and Sunday.