textproduct: Duluth

KEY MESSAGES

- Near to slightly below average temperatures are expected on Monday with partly cloudy skies. Marine fog may develop over Lake Superior tonight and move 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 from the Brainerd Lakes to the I-35 corridor. 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

Conditions today have been pleasant across the Northland with temperatures slightly below normal for mid June. Latest surface analysis shows high pressure located in the vicinity of the CWA, with one sfc high being located around Lake Winnipeg and another over central Lower Michigan. As an upper level low currently located over northern Ontario propagates downstream and a weak 500mb ridge slides east into the region on Monday, this will maintain benign conditions today through Monday. Diurnal heating has developed scattered cumulus, which will be dissipating this evening around sunset.

For tonight, expect mostly clear to clear skies with low temps cooling to the mid 40s. As winds become calm due to high pressure propagating towards Lake Superior, this will allow for potential marine fog develop and an advection of this fog onshore on Monday as light northeast winds occur. Any marine fog that does advect inland will likely dissipate late in the morning into the afternoon as diurnal heating and subsequent mixing occurs. For areas inland, tomorrow will very similar to today with another cumulus field developing from diurnal heating.

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 /18Z TAFS THROUGH 18Z MONDAY/

Issued at 1232 PM CDT Sun Jun 21 2026

Diurnal VFR height cumulus will continue this afternoon across most of the region, expected to dissipate around sunset as diurnal heating ends and diurnal cooling begins. Models indicate that fog development is likely over Lake Superior tonight, which could be advecting inland. However, the current expectation is that this marine fog will remain below the hill and not impact KDLH. VFR conditions continue tomorrow morning, with high-level clouds moving in.

MARINE /FOR NEARSHORE WATERS OF WESTERN LAKE SUPERIOR/

Issued at 250 PM CDT Sun Jun 21 2026

As high pressure moves towards Lake Superior today into tomorrow, winds are expected to become more variable with speeds of 5 kts or less on Monday for most of the nearshore waters. As winds ease tonight, fog development will be possible across western Lake Superior. Confidence in this is moderate, as several, but not all, high resolution models strongly suggest fog. If fog does develop, this will persist through much of tomorrow, especially along the South Shore as light northeast winds advect fog inland.

Due to light winds, waves will be 1 foot or less today through tomorrow. 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

High pressure descending into the region from Manitoba tonight into tomorrow is expected to result in moderately dry min RH on Monday in the 30-40% range. While this Canadian High will produce drier RH, winds will be light and variable with speeds around 5 mph or less. Similar to today, another cumulus field will likely develop late Monday morning and persist until around sunset. 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 from the Brainerd Lakes to St. Croix River Valley where 0.5" to 1" of rainfall is forecast. Expect lesser rainfall amounts farther north in the Arrowhead and Rainy Lake area, 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.