textproduct: Duluth

KEY MESSAGES

- There is a slight risk (level 2 out of 5) for scattered strong to severe thunderstorms late this afternoon and evening.

- Cooler fall weather moves in Saturday and into the foreseeable future.

- Widespread rain and thunderstorms are likely Monday and Monday night. Severe weather is not expected.

DISCUSSION

Issued at 131 PM CDT Fri Sep 11 2026

Current Conditions:

The strong low level jet from the last night has helped to bring some scattered showers across the Northland as a ribbon of warm air advection between 925-850mb pivots over the region. This activity continues to slide northeast largely over Lake Superior and portions of the Arrowhead.

This afternoon and evening:

A surface low pressure over SD is set to swing northeast through the Northland helping to produce favorable conditions for severe weather this afternoon and evening. Strong southerly flow can already be observed across the Upper Midwest with gusts in excess of 25 mph advecting higher dewpoints in from the south. Model soundings indicate a very unstable air mass will be over the region by the afternoon with MLCAPE on the order of 1500+ J/kg. There is a subtle cap seen in several models between 800-750mb. So the question will be whether we can generate enough surface heating to overcome this cap in the afternoon. If we can manage to break the cap then storms will have a very favorable environment to grow in. Mid level lapse rates are quite steep aiding in air parcel acceleration leading to rapid storm growth to produce large hail and damaging winds. These discrete cells would have access to some favorable helicity with decent curvature in the hodograph indicative of a tornado threat. Overall the area most favored for this development would be from the Brainerd Lakes region into the Twin Ports and up through northern MN. Best timing for this set up would be 3PM to 6PM. However, confidence in this solution is not overly high, especially with the added cirrus clouds rolling in from the west. But given the favorable parameter space for storms it can't be ignored.

This evening is when the better chances for more widespread showers and storms overtake the Northland. Synoptic forcing increases as an upper level shortwave moves in tandem with the surface low into western MN. There is good agreement amongst the high res guidance for an expansion of showers and storms across the Red River Valley and through northern MN beginning at 6 PM and onwards into the evening. Brief discrete storm mode will be possible initially, but the mean wind flow is more parallel to the boundary which will lead to congealing of storms as we quickly move to a more linear mode. Damaging winds and some large hail will become the primary threats at this time. Severe potential looks to taper off around 10 PM with showers and storms lingering through the overnight period. Additionally, heavy rain threat may also come into play. PWATs are forecasted to be around 1.50-1.60" which is near the 90th percentile of climatology. If we get some training storms the HREF LPMM is highlighting some swaths of 3+ inches possible. Not expecting this to be widespread but something to monitor, current 3hr flash flood guidance is largely over 1.5" across northern MN.

The weekend:

After today's system moves through we will see a quiet and cool weekend. Surface high pressure will be moving from the Canadian Prairies down towards the Great Lakes. Highs will be in the 60s and low 70s on Saturday with even cooler temps on Sunday forecasted to stay in the 60s. Clear skies on Sunday night may prompt some very chilly overnight lows. Opted to nudge our temperatures down into the mid 30s. Patchy frost may develop and if temperatures continue to trend cooler a Frost Advisory may be needed.

Next Week:

The cool temperatures look to persist through much of the week before we start to warm back up into the low 70s on Friday. Rain chances return Monday as a vertically stacked low moves across Manitoba into Ontario. This system looks to have an impressively strong upper level jet associated with it promoting a highly sheared environment. The region is lacking in the instability department with low MUCAPE forecasted. Overall expecting this to largely manifest as rain showers with an occasional rumble of thunder.

AVIATION /18Z TAFS THROUGH 18Z SATURDAY/

Issued at 1222 PM CDT Fri Sep 11 2026

Gusty winds out of the south to start the forecast period. The region is within a warm sector with several echoes developing on radar this afternoon. Scattered showers and thunder storms will be possible this afternoon some of which may be severe. Later this evening storm coverage will expand and march west to the east through the overnight hours. This activity will move off to the east by tomorrow morning with widespread VFR conditions expected thereafter.

MARINE /FOR NEARSHORE WATERS OF WESTERN LAKE SUPERIOR/

Issued at 131 PM CDT Fri Sep 11 2026

Strong south winds continue to stream across Lake Superior this afternoon with Small Craft Advisories in place into tomorrow morning. Overnight, showers and thunderstorms will impact the Lake into the morning hours as well. Primary hazards would be strong winds and frequent lightning. A cold front will sweep in from the west tomorrow morning leading to a wind shift. Winds behind this front will likely warrant another Small Craft Advisory as these westerly winds linger through Saturday. Conditions briefly quiet down for Sunday as high pressure cross the region. Winds look to ramp up once again on Monday as another system moves across Canada.

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

FIRE WEATHER

Issued at 131 PM CDT Fri Sep 11 2026

Low fire weather concerns. Active weather this afternoon and evening with showers and thunderstorms expected to develop over MN and spread east overnight. Quiet weather for the weekend with cooler temperatures on tap. Rain chances return on Monday.

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 until 4 AM CDT Saturday for LSZ121- 140>148-150.