NWS extends fog and small craft advisories for St. Louis County waters

Small boat traffic on the North Shore needed to stay in port as the National Weather Service in Duluth extended Dense Fog and Small Craft Advisories for waters from Two Harbors to Duluth and from Grand Marais to Taconite Harbor through April 28.

The warning covered Lake Superior waters within five nautical miles of shore, where northeast to east winds were forecast to build to 15 to 25 knots and waves were expected to reach 4 to 6 feet, with occasional 7- to 8-foot breakers. In the Grand Marais to Taconite Harbor zone, forecasters said a gale warning may be needed, a sign that conditions could worsen quickly for fishing boats, charter traffic and anyone running nearshore routes.

Dense fog added another layer of danger. Earlier marine wording from the Duluth forecast office said visibility could fall to 1 to 2 nautical miles, making it hard to judge distance, boat position and incoming traffic along the Lake Superior shoreline. The weather service has said those conditions are hazardous for navigation and that smaller vessels should avoid them when possible, especially when waves, wind and low visibility combine.

For people on shore, the impact extended beyond the waterline. Harbors, landings and shoreline roads near Duluth, Two Harbors and the North Shore were at risk of slower traffic and reduced visibility as boats, anglers and shipping crews adjusted to the weather. The advisory also came as the Northland faced a separate rainfall threat, with the weather service saying much of the region had at least a 50% chance of an inch of rain and parts of the North Shore corridor had a 40% to 60% chance of 2 inches or more. That raised the possibility of minor flooding, and a Flood Watch was in effect for the Arrowhead Monday and Monday night.

The weather service notes that its Great Lakes nearshore marine forecasts begin around April 1 and run through December 31, depending on ice conditions. That seasonal window matters on Lake Superior, where spring can shift from manageable to dangerous in a matter of hours. Duluth’s event summaries point to the April 13-15, 2018 snow, wind and big-wave event as a reminder that the lake can turn hazardous fast, even when winter is already supposed to be fading.