textproduct: Duluth

KEY MESSAGES

- Widespread showers and thunderstorms are expected tonight into Tuesday morning. A few storms may become strong to severe, capable of producing damaging winds, large hail, and very heavy rainfall.

- Strong west-northwest winds are very likely on Wednesday, with gusts of 30 to 40 mph forecast. Winds are most likely to be strongest in the Minnesota Arrowhead.

- Additional precipitation chances arrive late this week into the weekend. A pattern change to cooler temperatures is favored this weekend into early next week.

DISCUSSION

Issued at 249 PM CDT Mon Sep 7 2026

Partly to mostly cloudy skies are occurring early this afternoon across the region ahead of an approaching 500mb trough. Ongoing southerly flow is expected to provide deep moisture advection into the CWA this evening into tonight, with IVT showing moisture coming both from the Gulf and some moisture from Tropical Storm Marie offshore from Baja California. The 12z sounding from KINL revealed an already moist PWAT of 1.47", which is above the 90th percentile of 1.14". As moisture advection occurs tonight, these PWAT values are progged to increase up to around 2", which would be towards, if not breaking, the max of climatology.

This surge of moisture, combined with a deep warm cloud layer in excess of 12,000 ft, will likely lead to localized very heavy rainfall rates this evening through tonight. Flash flooding concerns are somewhat mitigated due to drier soil moisture conditions across a large portion of the CWA, although areas north of the Laurentian Divide show soil moistures in the 50-60% range per MRMS CREST soil moisture. That being said, there is still a minor concern for flash flooding tonight, including the northwest Wisconsin portion of the CWA, as very heavy rainfall occurring over the areas experiencing Extreme (D3) drought could potentially lead to rapid runoff.

In terms of QPF, heaviest rainfall is expected to be overnight as a quasi-stationary warm front remains parked north of the CWA and a cold front approaches from the west. 24-hour LPMM QPF forecasts from the 12z HREF suggest the potential for 2-3" of precip occurring from multiple rounds of showers and thunderstorms moving through tonight into early Tuesday morning. Confidence in the area of heaviest QPF is fairly low, although it does appear more likely along and south of US-2, where PWATs will be higher. Storm motion will be relatively progressive tonight, which limits flood concerns, although training storms will be something to monitor tonight into tomorrow morning.

Besides potential flash flood concerns, there is also a Marginal Risk for severe thunderstorms today through tonight for portions of north-central MN around the Brainerd Lakes. MUCAPE per the RAP is forecast to increase in excess of 1000-1500 J/kg overnight, with a stout 850mb LLJ of 30-40 knots and 0-6 km bulk shear of 40-50 knots. These overnight storms will most likely be elevated, with large hail and damaging winds being potential hazards. Confidence in severe storms tonight is low, as CAMs show somewhat weak mid-level lapse rates and the warm nose associated with the LLJ will likely keep storms decoupled from the surface.

A Marginal Risk for severe thunderstorms persist on Tuesday morning in the Arrowhead, I-35 corridor, and northwest Wisconsin. However, this threat of severe storms will most likely be remnants of the convection tonight as the cold front sweeps through and will therefore share similar limitations to severe hazards as previously mentioned. Expect showers and thunderstorms to largely come to an end across the CWA by Noon on Tuesday. Sprinkles and the occasional shower may linger through the afternoon as the sfc cold front continues to move through.

Following the cold frontal passage on Tuesday, a more benign pattern settles over the CWA around mid-week as high pressure builds. Ahead of this high pressure, west-northwest winds are very likely to become strong during the daytime hours on Wednesday. Wind gusts of 30-40 mph are forecast, strongest in the Arrowhead. A few gusts in excess of 40 mph are not totally out of the question, although the NBM probability for inland locations along the North Shore is a low 10-20%. Wind Advisories may be needed on Wednesday, especially if winds show an increasing trend.

The next chance for precipitation arrives late into the week into the weekend as additional troughs potentially propagate through the CWA. One upcoming pattern change of note is a temperature change arriving this weekend into early next week. While high temps most of this workweek will be in the 70s for most, high temps by this weekend into early next week will likely be in the 60s (with a few upper 50s not out of the question!).

AVIATION /18Z TAFS THROUGH 18Z TUESDAY/

Issued at 1248 PM CDT Mon Sep 7 2026

Partly to mostly cloudy skies are expected this afternoon, with cigs being predominately VFR, and breezy southerly winds. Occasional reductions to MVFR are expected to occur this afternoon. Widespread showers and thunderstorms arrive tonight, which is anticipated to lower conditions to MVFR and IFR. A few storms around KBRD may become strong to severe, capable of producing large hail and damaging wind gusts. Elsewhere, the main concern is very heavy rainfall. Expect showers and thunderstorms to begin exiting from west to east starting late tonight and continuing into Tuesday morning.

MARINE /FOR NEARSHORE WATERS OF WESTERN LAKE SUPERIOR/

Issued at 249 PM CDT Mon Sep 7 2026

Winds will continue to increase this afternoon and evening, slowly turning to the south this evening. By early Tuesday morning, widespread wind gusts of 25 knots or greater are expected across western Lake Superior, with gales expected from Grand Portage to Grand Marais. The Gale threat diminishes Tuesday afternoon, although a Small Craft Advisory will likely be needed for these nearshore waters Tuesday afternoon. Widespread Gales continue to look likely for Wednesday as a tight pressure gradient develops. Therefore, a Gale Watch was issued across western Lake Superior on Wednesday.

Outside of the expected elevated winds, thunderstorms are forecast tonight into early Tuesday morning. A few storms may be strong to severe, capable of producing wind gusts in excess of 34 knots, large hail, and frequent cloud-to-water lightning.

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

FIRE WEATHER

Issued at 249 PM CDT Mon Sep 7 2026

Widespread showers and thunderstorms are expected to arrive tonight and continue into Tuesday morning, accompanied by strong south winds. At least 0.5" of rainfall is forecast across the area, with the potential for localized amounts of 2-3" most likely to occur along and south of US-2. Expect gusty and erratic winds around thunderstorms, in addition to frequent lightning and potentially large hail. Expect a gradual wind shift to occur on Tuesday, with winds coming from the west-southwest by Tuesday evening as a cold front moves through.

Strong west-northwest winds are very likely to arrive on Wednesday, with the potential for gusts of 30-40 mph. Strongest winds on Wednesday are most likely to be in the Arrowhead, especially on exposed ridges. While winds will be strong, lingering moisture will result in min RH of 40% or greater on Wednesday afternoon. Winds ease Wednesday evening as high pressure builds into the area.

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

DLH WATCHES/WARNINGS/ADVISORIES

MN...None. WI...None. MARINE...Small Craft Advisory from 4 AM Tuesday to 7 AM CDT Wednesday for LSZ121-142>148-150. Gale Watch from Wednesday morning through Wednesday afternoon for LSZ121-140>148-150. Small Craft Advisory from 7 PM this evening to 4 AM CDT Tuesday for LSZ140. Gale Warning from 4 AM to 1 PM CDT Tuesday for LSZ140. Small Craft Advisory from 7 PM this evening to 7 AM CDT Wednesday for LSZ141.