Marine Weather and Tide Forecast for Grand Marais, MN

DISCUSSION
Issued at 304 PM CDT Mon Jun 16 2025

Some clearing over the Brainerd Lakes area has lead to increased instability to where it was expected (up to 2000 J/kg) and wind shear 30-40 kts with sufficient low level turning has increased the tornado threat across that area. Plus, the high CAPE and large hail growth zone could lead to some large hail with these storms as well. Later on in the evening, however, we will lose the ideal low level turning and some instability as the storms move east. The threat for very large hail (up to 2 inches) will diminish, and the threat for large hail (up to 1.25 inches), damaging winds, and a marginal threat for tornados continue.

Due to wrap around precipitation at the top of the system moving through northern Minnesota, portions of the Iron Range and the Arrowhead will see higher rainfall totals from the abundance of moisture wrapping around the low. Exactly how much will fall at any given location will depend on the path and longevity of the convection on the north side of the low.
Isolated areas over an inch is possible, though most will get a half to three quarters of an inch.

Continued northwest flow and a few rounds of shortwaves will lead to scattered precipitation into the mid week. These showers and storms won't be particularly exciting, and coverage across the area will likely be along the International Border and towards central Minnesota/Wisconsin. Wednesday into Thursday, a deeper upper level trough will pull cool air down from Canada to initiate showers and storms across the area. Higher instability and wind shear is shown across global models, particularly across northwest Wisconsin Thursday afternoon, could lead to some stronger storms.

Friday night into Saturday, a warm front begins to move northeast into our area. With this will come another chance for thunderstorms at the front end of a good LLJ throughout the night. Sunday will see temperatures in the upper 80s behind the warm front, and dewpoints in the 60s will make it feel hot and sticky.

AVIATION /18Z TAFS THROUGH 18Z TUESDAY/
Issued at 1232 PM CDT Mon Jun 16 2025

Thunderstorms are abundant this afternoon, with the current cluster of storms near BRD. More storms will form in the Northland throughout the afternoon, with potential IFR visibilities with the heaviest precipitation. Storms near BRD currently have the greatest potential of being severe, with damaging winds, hail up to 2 inches, and a tornado or two are possible. The greatest likelihood of passing storms over each terminal are laid out in TEMPO groups. There is the potential for more fog tonight as well after the storms, but uncertainty is high at the moment.

MARINE /FOR NEAR SHORE WATERS OF WESTERN LAKE SUPERIOR/
Issued at 304 PM CDT Mon Jun 16 2025

Marine weather is quiet after today, showers and storms will move over Lake Superior this evening, with the largest threats being strong winds and cloud-to-water lightning. On and off chances for general thunderstorms continue for the next couple days.

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

DLH WATCHES/WARNINGS/ADVISORIES
MN...None.
WI...None.
MARINE...None.