textproduct: Duluth

KEY MESSAGES

- Two rounds of strong to severe storms are possible today. First round this morning. Second round late afternoon through evening. Northwest Wisconsin has the greatest risk of severe storms.

- Hot and muggy conditions are expected over northwest Wisconsin. Heat Advisories are in effect.

- Shower and storm chances persist Wednesday through the end of the week. Some of those storms may be strong to severe with the greatest risk during the period on Wednesday.

UPDATE

Issued at 421 AM CDT Tue Jun 30 2026

A brief lull is expected early this morning between departing showers and storms over the tip of the Arrowhead and portions of northwest Wisconsin and the next possible round of storms late this morning. We're monitoring an area of thunderstorms over south-central Minnesota back to northwest Iowa. Those storms are forecast to move east-northeastward through the early morning hours. High-res model guidance seems somewhat split on what will become of those storms. Nearly all of the guidance brings precipitation into northwest Wisconsin later this morning. Several models, including the NAMNest, RAP and HRRR, carry remnants of the storms into our area by around 8 AM. They vary in the intensity of the storms when they arrive. There is at least a small chance the storms could produce gusty winds and large hail, although the radar trends over the past hour seem to suggest a general weakening trend is more likely.

As of 4 AM CDT... A surface warm front was located over portions of the I-35 corridor and northwest Wisconsin and is forecast to advance farther north to the Canadian border by late this morning. Surface winds will turn southerly behind the front ushering in warm and moist air. The warmest temperatures and highest dewpoints today will be over northwest Wisconsin. The Arrowhead of Minnesota will see lake-modified temperatures and humidity keeping conditions a bit more comfortable. Farther west over central and north-central Minnesota, a cool front approaching from the west will limit heat and humidity as well.

The afore mentioned cool front will propagate eastward into the I-35 corridor by early afternoon. Regardless of whether the afore mentioned morning storms survive into northwest Wisconsin, ample destabilization is forecast ahead of the cold front to support thunderstorm development. The kinematic parameter space is pretty noisy among the various models and reveals considerable uncertainty as to the details of how things may evolve. The majority of the hi-res guidance and the NAM feature hodographs with clockwise curvature in the lowest 3km. Above that level the details begin to differ. Supercells are possible given the deep layer shear and favorable hodographs. There are questions as to how deep a mesocyclone could be sustained since most of the profiles either turn counter-clockwise above 3km or the tails become shorter due to similar wind vectors aloft. All modes of severe weather are on the table as of this morning. Higher confidence may develop after we see how the morning storms resolve.

Remainder of the forecast is on track.

UPDATE

Issued at 1259 AM CDT Tue Jun 30 2026

Another strong line of thunderstorms is moving through the Northland tonight, with embedded severe storms producing large hail, damaging winds, and tornadoes are still not out of the question. However, this line is moving into a less and less favorable environment, so they are expected to decrease in intensity in the next few hours.

DISCUSSION

Issued at 128 PM CDT Mon Jun 29 2026

For the rest of the day, our primary concerns will be the oppressive heat and the severe weather threat. Extreme Heat Warnings and Heat Advisories remain in effect for the southern half of the Northland. We are noting that CAMS guidance is not doing well, but there is plenty of CAPE with storms riding along a warm front. In addition, rich PWATs of 2.4+ inches giving heavy rainfall with warm sector inflow providing dewpoints in the 80s. This incredible moisture is pushing heat index values well past the 100 degree mark for many of our southern communities. Meanwhile, a Severe Thunderstorm Watch remains in effect until 4 PM for all of northeast Minnesota.

The current storm moving through St. Louis County presents itself very similar to the radar presentation of the 1999 BWCA blowdown storm with similar timing too! Thus far, this storm hasn't been too effective in bringing down winds to the surface, at least in the last 3 hours; however, the environment over NE Minnesota is rich as a little clearing occurred to allow the storm to become more surface based increasing the threat for winds as it moves through the Arrowhead. Similarly, the storm's southern end also is beginning to take on a identity of its own and should run east into the higher richer moisture. Should be an active afternoon. In addition to the storm threat, there is a wake low that is causing really strong winds in the wake of the convective line which could gust to 50 to 60 mph!

As we move into the evening and overnight hours, the threat for severe weather continues. Models continue to indicate that redevelopment is likely this evening causing a second line of storms to cross through the BWCA. Given the extreme instability and moisture in place, these storms will pose a substantial risk for large hail, damaging winds, and intense downpours capable of localized flooding. Temperatures tonight will provide little relief from the heat, with lows struggling to fall below 70 degrees in many locations.

For tomorrow, a cold front will slowly work eastward across the region. Heat Advisories will linger for our northwest Wisconsin counties as temperatures once again climb into the 90s, though drier air will slowly filter into Minnesota. Instability will pool ahead of the advancing front, bringing another round of strong to severe thunderstorms, especially during the afternoon hours across northwest Wisconsin. Large hail and damaging winds will once again be the primary hazards.

Looking ahead to Wednesday, the active summer pattern will persist. We will maintain southwesterly flow aloft as a shortwave passes through the region. This will bring additional chances for scattered showers and thunderstorms, some of which could be strong given the lingering instability. Temperatures will remain quite warm, generally in the 80s to near 90 degrees, ensuring the humid feel sticks around the area.

For Thursday through the upcoming weekend, broad ridging will remain anchored to our east with troughing to the west. This setup keeps the Northland in a warm and active southwest flow regime. Expect daily chances for showers and thunderstorms, particularly during the afternoon and evening hours. High temperatures will remain somewhat steady in the 80s. While not every day will be a washout, anyone with outdoor holiday weekend plans should monitor the forecast closely.

AVIATION /12Z TAFS THROUGH 12Z WEDNESDAY/

Issued at 645 AM CDT Tue Jun 30 2026

A brief period of mist and fog may form at the terminals before 13Z. Otherwise expect VFR conditions with gusty winds today. A cool front will move over the region from the west and DLH and HYR have small chance of thunderstorms this afternoon. The chance of storms at DLH from late morning through the afternoon is around 15% and at HYR the probability is around 20%. Those are two low to include explicitly in the forecast for now. There is a 10% chance of additional storms at HYR after 01.10Z.

MARINE /FOR NEARSHORE WATERS OF WESTERN LAKE SUPERIOR/

Issued at 645 AM CDT Tue Jun 30 2026

Fog has cleared in the near shore waters for the time being from the line of storms moving through. However, fog is expected to redevelop and cause visibilities less than a mile into the morning. Winds out of the southwest will be 15 kts or less for the next couple days. Wind and waves may become hazardous to smaller vessels near Grand Portage during the afternoon and evening hours of Wednesday and Thursday. Small Craft Advisories may eventually be needed.

For the open water discussion, refer to the NWS Marquette Area Forecast Discussion at weather.gov/mqt.

FIRE WEATHER

Issued at 1259 AM CDT Tue Jun 30 2026

Today will be the driest day this week with RH in the 35-45% range this afternoon. Hot temperatures and high dewpoints are expected to linger, particularly in northwest Wisconsin. This will only be a brief relief for Minnesota, though, as hot temperatures and high dewpoints are expected for the remainder of the week. Winds will be out of the west to southwest for the mid week, with gusts to around 20 mph.

See the Fire Weather Forecast product for a more thorough breakdown of fire weather conditions.

DLH WATCHES/WARNINGS/ADVISORIES

MN...None. WI...Heat Advisory until 7 PM CDT this evening for WIZ002>004-008- 009. MARINE...Dense Fog Advisory until 8 AM CDT this morning for LSZ121- 140>148-150.