textproduct: Duluth

KEY MESSAGES

- Marine fog over Lake Superior this morning could reduce visibility along the South Shore as it moves inland.

- Widespread showers and thunderstorms arrive on Tuesday, moving from west to east into early Wednesday morning.

- A few storms Tuesday afternoon and evening may become strong to severe west of a line from Aitkin to Nett Lake. Damaging winds and marginally severe hail to 1" in diameter are potential hazards.

- Additional chances for precipitation linger on Wednesday into Thursday with more rain possible late Saturday into Sunday.

DISCUSSION

Issued at 250 PM CDT Sun Jun 21 2026

The next chance for precipitation arrives on Tuesday as vertically- stacked low pressure and an associated shortwave move into the Upper Great Lakes. Cloud cover is anticipated to increase on Tuesday morning ahead of an approaching warm front and subsequent occluded front. Scattered to numerous showers and thunderstorms are expected (80-95% chance) to move from west to east through the CWA on Tuesday afternoon into Wednesday morning. Current QPF is forecast to be highest from the Brainerd Lakes to I-35 corridor and into north- central WI, with values ranging from around 0.5" to 1".

A few storms on Tuesday afternoon and evening may become strong to severe from the Brainerd Lake to around the I-35 corridor, where SPC has issued a Marginal Risk on Tuesday. While the shear environment will likely be favorable for stronger convection, with 0-6km bulk shear in the 30-45 knot range, instability and moisture will likely be the limiting factors. The primary window for any strong to severe convection will most likely be from 18-02z, as a surge of higher dewpoints up to the low 60s advects north along the warm front. This will help generate modest MLCAPE up to 1000 J/kg in the southern portion of the CWA when combined with marginally steep mid-level lapse rates around 7 degC/km. Confidence in severe convection is low at this time, as the best PWATs and instability will most likely remain south of the CWA. In addition, this severe chance is largely dependent on how far north the warm front advects before the occluded front arrives. If severe storms are able to develop this far north, the main concern is damaging wind gusts and marginally severe hail.

Following this mid-week severe weather chance, a fairly active pattern is favored in the global models over the Upper Midwest. The 250mb jet streak helping to propagate the verticall-stacked low into the region on Tuesday will begin weakening on Wednesday, slowing the eastward progression of this low and keeping rain chances around on Wednesday. Thursday will see additional rain chances, most likely from diurnal showers developing in the afternoon as cyclonic flow aloft persists. Heading into the weekend, a brief lull in rainfall will be possible as a ridge builds over the Upper Mississippi River valley. Additional shower and thunderstorm chances arrive though late Saturday into Sunday as another low pressure and associated warm front potentially moves into the north-central CONUS.

AVIATION /12Z TAFS THROUGH 12Z TUESDAY/

Issued at 627 AM CDT Mon Jun 22 2026

VFR conditions with light winds are forecast through 23.12Z as high pressure remains over the region.

Fog has developed over western Lake Superior and spread inland over portions of the South Shore. That fog would likely remain limited to KASX, KSUW, and KDYT, and is not expected to impact forecast terminals.

MARINE /FOR NEARSHORE WATERS OF WESTERN LAKE SUPERIOR/

Issued at 250 PM CDT Sun Jun 21 2026

With light winds over Lake Superior tonight, fog has developed with visibility reductions spreading into nearshore waters along the South Shore. Cannot rule out this fog making it into the Twin Ports before sunrise.

As high pressure remains near Lake Superior today, winds will remain variable with speeds of 5 kts or less for most of the nearshore waters. Waves will be 1 foot or less. Widespread rain chances arrive on Tuesday, with strong thunderstorms capable of producing gusty winds, small hail, and frequent lightning possible in the afternoon and evening.

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

FIRE WEATHER

Issued at 250 PM CDT Sun Jun 21 2026

With high pressure remaining over the region, moderately dry min RH is expected today, in the 30-40% range. Winds will be light and variable with speeds around 5 mph or less. Mid and high level clouds are spreading into the area from the west this morning, which could slow warming after the sun rises, keeping min RH values slightly higher than currently expected.

Widespread showers and thunderstorms are expected (80-95% chance) to arrive on Tuesday into Wednesday as low pressure moves through the area. A few storms may become strong to severe on Tuesday afternoon and evening, especially west of a line from Mille Lacs Lake to Nett Lake. This area could also see 0.5" to 1" of rainfall. Expect lesser rainfall amounts farther east in the Arrowhead and across northwest Wisconsin, with as little as 0.05" of rain forecast in most of Cook County.

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.