textproduct: Duluth

KEY MESSAGES

- Strong to severe storms are possible this afternoon and evening ahead of a cool front. The Northland is under a Marginal Risk, level 1 out of 5 for severe storms with the primary threat being damaging winds and a smaller risk of large hail and tornadoes.

- Locally heavy rainfall is possible with thunderstorms and may lead to localized minor flooding. The threat is highest over the Arrowhead and northwest Wisconsin.

- Near-critical fire weather conditions return Friday.

DISCUSSION

Issued at 225 PM CDT Thu Apr 23 2026

This afternoon and tonight...

Skies cleared over northwest Wisconsin this morning and temperatures rose into the low to middle 70s. Farther west overcast skies persisted keeping temperatures in the low to middle 60s. Isentropic lift over Minnesota supported a slowly expanding area of showers over central and southwest Minnesota stretching north to just west of Duluth. Coverage of showers and storms will increase through the remainder of the afternoon.

GOES-East infrared and visible imagery revealed an area of weak subsidence over southwest Minnesota into western Iowa. Visible imagery featured a narrow area of clearing just ahead of the storms which developed between 1830Z and 1915Z. There will likely be a slight increase in MLCAPE in that clear slot.

Storms over central and southwest Minnesota may become surface- based as the cap erodes and MLCAPE increases. RAP sounding from near St. Cloud reveals cyclonic curvature in the hodograph between the surface and 2 km with the greatest curvature in the 0-1km layer. The tornado potential remains smaller than the risk of hail and damaging winds though it may increase as the clearing expands farther north. The sunshine and warmer temperatures will support MLCAPE of 1000-1500 J/kg by late afternoon over northwest Wisconsin. A capping inversion around 700 mb will gradually erode by early evening which will enable storms to become surface based. Forecast hodographs feature limited directional shear and trajectories are nearly stacked above 3 km. Storms will benefit from low- level ascent enhancement though parcel evacuation will be limited in the top half of the storm. Thus precipitation will fall back through the updraft limiting storm intensity. Initial discrete storms will pose the greatest hail and tornado risk while later storm mergers and cold pool interactions will support a shift toward damaging wind risk with time. Hail up to quarter size, wind gusts up to 70 mph, and a small risk of one or more tornadoes are the threats through this evening. There is a small risk of one or two storms producing hail up to ping-pong ball size.

Heavy rainfall remains a concern due to PWATs over an inch, the moist profiles and the potential for training storms. The greatest risk of excessive rainfall and minor flooding is over northwest Wisconsin and the Minnesota Arrowhead (where there remains noteworthy snow pack and recent melting).

Rain and storms will become widespread over the eastern half of the Northland during the evening and will gradually shift eastward overnight ahead of the approaching cold front. Temperatures will dip into the middle and upper 30s over north- central Minnesota to around 40 degrees in the Arrowhead and low to upper 40s in northwest Wisconsin.

Friday through the weekend...

The cutoff low will remain over the Canadian Prairies. Rain and a few embedded thunderstorms may still linger over the Arrowhead and portions of northern Wisconsin and western Upper Michigan. Temperatures will trend cooler with near-normal highs from the middle 50s to the low 60s. Very dry conditions are forecast with afternoon humidity values between 20 and 35 percent in Minnesota west of the I-35 corridor north to the Canadian border. The Arrowhead and much of northwest Wisconsin will not dry out as much due to clouds and precipitation loiter longer over those areas. Lows Friday night will dip below freezing north of a line from Northome to Two Harbors (except shoreline areas of Lake and Cook counties) and the middle 30s farther south.

Temperatures remain near to slightly above normal for Saturday and Sunday. Both days appear to be dry with low RH values forecast. The latest guidance hints at a chance of showers or possibly a thunderstorm or two Saturday night and early Sunday morning somewhere over the northwest quarter of Minnesota. Rain amounts would be small, less than a tenth of an inch. GFS is a bit more broadbrushed with precipitation from west-central Minnesota to northeast Minnesota.

Monday through next week...

The cutoff low over the Canadian prairies is forecast to drift slightly farther north early next week. Deterministic solutions point to a low pressure system taking shape over the Midwest Monday and Tuesday. Rain and perhaps a few thunderstorms are likely during that period. Ample poleward moisture advection with that system raises a concern about minor flooding depending on the location and duration of the rainfall. The closed low is forecast to meander around the Canadian prairies and northern Plains into late next week before it advances east toward New England. Additional precipitation chances and near to below normal temperatures are forecast. There is a potential for a few snowflakes Thursday and Friday.

AVIATION /18Z TAFS THROUGH 18Z FRIDAY/

Issued at 114 PM CDT Thu Apr 23 2026

Showers and storms are forecast to develop and spread northward into the terminals this afternoon. MVFR ceilings at HIB, INL, and BRD will persist and trend lower as showers and storms develop. MVFR ceilings will return to DLH and HYR later this afternoon. The heavier storms will produce periods of IFR or LIFR visibility. Small hail is possible with the storms near HYR. Ceilings will lower to IFR tonight and will give way to VFR conditions on Friday. Winds will shift northwesterly behind a cool front overnight and may become gusty again Friday.

MARINE /FOR NEARSHORE WATERS OF WESTERN LAKE SUPERIOR/

Issued at 114 PM CDT Thu Apr 23 2026

Persistent easterly and northeast winds over western Lake Superior will build waves to 2 to 5 feet along portions of the North Shore tonight. Gusts of 20 to 25 knots are possible near Grand Marais and Grand Portage. There is a small chance of thunderstorms over western Lake Superior this afternoon and evening. Occasional cloud-to-water lightning, wind gusts to 40 knots, and hail up to quarter size are possible with the strongest storms.

A cool front will move eastward over the waters tonight and Friday with winds turning northwesterly. Waves will gradually subside Friday. Strong gusts are possible from Silver Bay to Grand Marais Friday morning. Wind and waves continue to diminish Friday night and should not pose a risk to boaters until Monday.

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

FIRE WEATHER

Issued at 114 PM CDT Thu Apr 23 2026

Rain and thunderstorms are expected this afternoon through early Friday morning ahead of a cold front. Rainfall amounts of a tenth to two inches are forecast. The higher precipitation totals will be in the eastern Arrowhead and portions of Sawyer, Ashland, Price and, Iron counties. Friday is shaping up dry once again over north-central Minnesota and the Brainerd Lakes with RHs from 20 to 35 percent. RHs will remain higher farther east as clouds and precipitation are slow to depart on Friday morning. Winds will be from the west at 5 to 12 mph with gusts of 10 to 20 mph. Saturday will be dry as well with RHs bottoming out in the 25 to 35 percent range. Winds will be lighter and variable turning south by late afternoon at 5 to 10 mph with gusts up to 15 mph. Sunday may see a bit more cloud cover and a chance of showers and storms. RHs will not be as low unless skies clear quickly behind the morning rain chances.

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.