textproduct: Duluth

KEY MESSAGES

- Showers and thunderstorms are expected today, with a few severe storms possible in portions of east-central MN and northwest WI this afternoon and evening. The primary hazard is large hail up to 1.5 inches in diameter.

- Scattered showers will be possible on Friday afternoon, mainly in the Arrowhead and near the International Border.

- Pleasant weather conditions are forecast this weekend with comfortable high temps in the 70s for most and abundant sunshine. Additional shower and thunderstorm chances arrive early next week on Monday and Tuesday.

UPDATE

Issued at 344 AM CDT Thu Aug 20 2026

Cloud cover has been increasing early this morning as a shortwave and associated sfc low move closer to the Northland. Scattered showers and isolated thunderstorms, currently in north-central MN, will continue to move east into the CWA as isentropic upglide along a lifting warm front occurs. Severe thunderstorms are not expected this morning.

The forecast remains similar to the previous update, with the potential for strong to severe thunderstorms occurring this afternoon and evening. The Storm Prediction Center also has maintained a Slight Risk for portions of the I-35 corridor into northwest WI, with a Marginal Risk covering areas generally south of the Iron Range. Southwest winds occurring ahead of an approaching cold front will provide deep moisture advection into the CWA, with dewpoints rising to the low to mid 60s by the afternoon. When combined with moderate mid-level lapse rates of 6-6.5 degC/km, this moisture and warmer temps in the upper 70s to low 80s are forecast to increase CAPE to 1000-1500 J/kg ahead of the cold front. This instability will also be occurring with favorable wind shear, with 0-6km bulk shear progged to be in the 30-50 knot range by late afternoon.

It's worth noting that a potential limiting factor for severe thunderstorm chances today is cloud cover from this morning round of convection. The current expectation is that there should be enough clearing occurring around midday to allow for destabilization to occur, but it will be something to monitor. Assuming that severe thunderstorms develop, the primary hazard will be large hail to 1.5" in diameter. Damaging winds to 60 mph will be a secondary hazard as DCAPE will most likely be under 1000 J/kg, and decreasing through the evening as the nocturnal inversion develops.

There are no major changes to the forecast following today's severe thunderstorm chances. A cold front is still forecast to sweep through late tonight into Friday morning, with the potential for scattered diurnal showers in the Arrowhead on Friday afternoon. Still looking at a pleasant weekend forecast, with abundant sunshine and comfortable high temps in the 70s. Additional rain chances arrive on Monday afternoon and again on Tuesday, with Tuesday being the next best day to monitor for severe weather chances.

DISCUSSION

Issued at 150 PM CDT Wed Aug 19 2026

A warm front lifts through the Upper Midwest late tonight into Thursday morning and brings about increasing rain shower chances will early Thursday morning. Isolated general thunderstorms develop Thursday daytime hour, first in the Brainerd Lakes area. By Thursday late afternoon, sufficient bulk shear approaching 50 knots and 1000 to 1500 J/kg of CAPE within an progged 1.5 to 1.7 inches of precipitable water favor a few severe thunderstorms first possible in the late Thursday afternoon hours, but mainly during the evening hours, lasting into the early overnight hours. Large hail to 1.5 inches in diameter is the most likely hazard, with damaging wind gusts being the secondary hazard. The area of most potential is south of the Iron Range towards the Twin Ports in the early evening and then areas further southward along the Interstate 35 and US Hwy 53 corridors in the mid to late evening hours. Localized rainfall up to 1.5 inches is possible from the strongest thunderstorms late Thursday evening, but most areas are more likely to receive 0.25 to 0.5 inches. While the most favored timing window for severe weather Thursday is 4-9 PM strong thunderstorms past 9PM to Midnight cannot be ruled out.

A cold front will drop through the area late Thursday night into Friday morning and bring a return to northwest flow across our region. A weak pool of instability will arrive by Friday afternoon and combine with ongoing daytime showers to produce some general thunderstorms, primarily focused from the Minnesota Borderlands into the Minnesota Arrowhead region.

Behind the cold front, high pressure will build into the Northland and provide a very nice and pleasant weekend. Abundant sunshine and comfortable temperatures in the 70s are expected for both Saturday and Sunday. The progressive pattern continues into early next week as the next round of more widespread thunderstorms is forecast for Monday afternoon and evening. Strong thunderstorms are again possible Monday afternoon and evening for north-central Minnesota. For Tuesday a primed environment may have finally setup over the Northland for another round of strong to potentially severe weather chances.

AVIATION /12Z TAFS THROUGH 12Z FRIDAY/

Issued at 631 AM CDT Thu Aug 20 2026

Showers with isolated thunderstorms are moving through the area this morning. Visibility and cigs have largely been VFR, although brief periods of MVFR visibility are expected under thunderstorms. There will likely be a brief lull between this morning convection and additional development occurring this afternoon and evening. A few storms may become strong to severe this afternoon and evening, especially in northwest WI, with large hail up to 1.5" being the primary hazard. As precipitation comes to an end tonight, patchy fog is very likely to develop. Confidence is increasing in widespread IFR to LIFR visibility, which was included in this update.

MARINE /FOR NEARSHORE WATERS OF WESTERN LAKE SUPERIOR/

Issued at 344 AM CDT Thu Aug 20 2026

Showers and thunderstorms are expected to arrive today and continue into tonight. A few strong storms capable of producing small hail are possible this afternoon and evening for the Twin Ports into the South Shore. East to northeast winds today are anticipated to remain 15 knots or less today, with waves of 2 feet or less. Winds will become west to northwesterly by the weekend following a cold front passage tonight into early Friday morning.

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

FIRE WEATHER

Issued at 344 AM CDT Thu Aug 20 2026

Showers and thunderstorms will move through today into tonight as a warm front lifts into the area this morning and a subsequent cold front sweeps through tonight. Since the center of the low pressure is expected to move through the area today, winds will be shifting through the day and speeds will generally be on the light side with peak sustained winds of 5-10 mph and afternoon gusts of 14 to 19 mph. A few storms this afternoon may become severe, especially from east-central MN into northwest WI. The primary hazard is large hail up to 1.5" in diameter, with gusty and erratic wind gusts up to 60 mph being a secondary hazard. A widespread 0.1" of rainfall today through tonight is expected, with wetting rains of 0.25" to 1" being more scattered and confined to thunderstorm cores.

Winds become northwesterly on Friday into the weekend following the cold front tonight. High pressure builds this weekend with abundant sunshine. Sunday looks to be the driest day in the forecast period, with min RH reducing as low as 35%. Additional shower and thunderstorm chances arrive on Monday into Tuesday.

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

DLH WATCHES/WARNINGS/ADVISORIES

MN...None. WI...None. MARINE...None.