textproduct: Duluth

DISCUSSION

Issued at 250 AM CDT Thu Apr 23 2026

Today:

A strong surface low over the Canadian Prairies is drawing in gulf moisture from the south this morning. Satellite shows a layer of stratus surging north from IA that is expected to breach our southern borders later this morning and eventually envelope the Northland before noon. There is also noticeable moisture advection working its way through the Midwest. Dewpoints are increasing by 4- 8F across southern MN and rushing north.

Through the morning hours we will see broad isentropic lifting moving over the region as we firmly remain in the warm sector with the low pressure moving into the Northern Plains. Some showery activity could develop in the morning hours with some embedded rumbles of thunder at times. But the better ingredients for showers and storms look to arrive in the afternoon hours.

As we head into the afternoon our better ingredients start to align for thunderstorm development. The latest CAMs are starting to come into better agreement with having the storm initiation being along our western counties or just to the west of them. Strength of these initial cells will be highly dependent on how the cloud cover evolves later this morning. If do manage to get a few sectors of sunlight that should allow some exponential growth in our instability. But for now, these areas of sun are more favored farther south. Browsing through some model soundings showcase an erosion of the cap in place around 2PM in the Brainerd Lakes region resulting in SBCAPE of around 1000 J/Kg with roughly 40 kts of bulk shear. Mean flow will be out of the southwest and could support a brief window of discrete cells developing before they congeal into a more linear mode as a cold front advances in from the west. Hodographs and low level helicity do show a very small window this evening between 5PM - 10PM where an isolated tornado threat could be possible along our southern tier counties.

SPC has maintained their marginal risk for the Northland. Initial estimates would be for storms to begin around 2-4PM across north central MN and march east through the afternoon and evening hours. As the storms take on a more linear form the primary hazard of concern will be damaging wind gusts up to 70 mph. Training storms in the southwest flow with PWATs over the max of climatology for GEFs does raise the concern for some flash flooding. REFS and HREF both favor NW WI with seeing the majority of the heaviest rainfall. Areas that see repeated rounds of storms could see cumulative QPF in excess of 2". The system is fairly progressive though with high res guidance having the cold front exiting overnight. The parameter space for severe weather falls apart fairly quickly after 11PM.

Friday:

On Friday the low pressure system that was moving across the Northern Plains retrogrades into the Canadian Prairies. An occluded front will be draped through the Arrowhead and may support some light rain showers. Farther west we may see some better drying conditions with clearing skies. Min RHs look to fall into the 20s and 30s once again which will raise concern for fire weather. Fortunately, winds don't look to get too out of hand at this time with gusts around 20 mph.

Weekend:

Ridging over the Atlantic holds the cut off low in place through the weekend allowing for some slightly cooler temperatures to remain over the region. Highs will be in the 50s and 60s with overnight lows in the 30s and 40s. There is some high uncertainty for weather concerns on Saturday. A lobe of PVA pin wheeling around the cut off low looks to move across the Central Plains with a weak surface low helping to produce some rain. This feature was previously expected to move across southern MN but the last models runs to come in have moved it into central MN. Our long term grids would suggest a fire weather concern for the day instead of precipitation, so we will need to see if this trend is just a one off for this set of models or if we need to make adjustments in the current forecast.

Early Next Week:

The pattern turns very active again with cluster analysis showing an upper level trough under cutting the low stuck over Canada. Early guidance would suggest that this will primarily turn into a rain event. Current track keeps the better instability out of the region. The slow going system will have lingering impacts through Tuesday as it moves into Ontario.

AVIATION /06Z TAFS THROUGH 06Z FRIDAY/

Issued at 550 AM CDT Thu Apr 23 2026

Strong low level jet encompasses most of the Northland this morning. After daybreak we should see better mixing of these winds to the surface with gusty souther winds becoming more prevalent. MVFR ceilings are already starting to stream into the Northland this morning with some rain showers off to our west. These rain showers could make it to BRD later this morning. The better chances for showers and storms will be this afternoon as a cold front pivots in from the west. Some storms will be strong to severe with primary threats being damaging winds.

MARINE /FOR NEARSHORE WATERS OF WESTERN LAKE SUPERIOR/

Issued at 250 AM CDT Thu Apr 23 2026

Easterly winds this morning along the North Shore will persist through the day. Waves will build along the North Shore. A cold front will move eastward across the waters Friday morning. Winds will back westerly and northwesterly and strengthen again by Friday afternoon. Scattered showers and thunderstorms are possible over the waters Thursday afternoon and evening. A few may be strong to severe. Small Craft Advisories are in effect for the Twin Ports into this morning and for the North Shore from this morning through Friday evening. Conditions may become hazardous again early next week due to waves and wind.

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

FIRE WEATHER

Issued at 250 AM CDT Thu Apr 23 2026

Active weather for today with showers and storms expected to develop in the afternoon and evening. Locally heavy rainfall will be possible with thunderstorms. Current guidance favors NW Wi for the heaviest rainfall amounts with training thunderstorms.

Drier air returns on Friday with clearing skies across our west. Min RHs may fall back to near-critical levels. Winds are expected to be out of the northwest with gusts around 20 mph in the afternoon.

High uncertainty for the weekend. Current forecast package features dry conditions which would prompt fire weather concerns. But the latest 00Z suite of guidance is starting to suggest some rain possible as a weak surface low moves through MN. Check back later to see how models have handled this latest change.

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 10 PM CDT Friday for LSZ140>143. Small Craft Advisory until 10 AM CDT this morning for LSZ144- 145.