Marine Weather and Tide Forecast for Grand Marais, MN

DISCUSSION
Issued at 349 AM CDT Sat Jun 14 2025

We're waking up with a mix of different conditions out there this morning. A broad area of rain is falling across northwest Wisconsin associated with a weak low-level jet bringing in plenty of warm air and moisture. This area of rain will stick around through the morning and we'll probably end up with plenty of ~0.5-1" totals by mid-day. Further north, where skies are mostly clear, temperatures have fallen into the 30s and 40s.
Isolated temperatures between ~30-36 degrees are occurring in the Arrowhead, and a Frost Advisory remains in effect there for this morning. We'll still be battling all that dry air to the north, and after the low-level jet weakens by mid-day, we can expect the organized rain in northwest Wisconsin to become more scattered this afternoon. The northeast flow will keep temperatures cool around Lake Superior and into northwest Wisconsin, but further north, another warm and sunny day is expected. Humidity is expected to fall into the 30-40% range along the Canadian Border this afternoon.

We get some more subtle shortwaves aloft and a redevelopment of a weak southerly low-level jet tonight, so we might get more showers to develop. It's not looking like amounts will be very impressive with maybe a few tenths of an inch possible. More robust instability and synoptic lifting to the south may result in thunderstorms, which may rob most moisture from making its way north tonight, thus keeping rainfall amounts on the lighter side. We will probably continue the trend of cloudy with perhaps some rain in northwest Wisconsin and some sunshine along the Canadian Border again on Sunday with that dry easterly flow dominating for one last morning before southerly flow develops Sunday afternoon.

On Monday, we're still looking at a threat for some strong to severe thunderstorms. A low amplitude trough embedded within the broader zonal flow may deepen a low pressure system across the upper Midwest. Plenty of warm air and moisture (PWATs ~1.5")
advection along with low-end favorable 0-6 km shear around 40 kt and instability on the low end around 1000 J/kg should promote the thunderstorm threat in and around our region. The track and timing of the low and attendant cold front is still uncertain, but will be important in determining how far north the severe threat will extend. If the low lifts further north, we'll be able to tap into more of the warm and unstable air ahead of the cold front. SPC has outlined a marginal risk (~5% chance) for severe storms for nearly all of the Northland and a slight risk (~15% chance) for southern Minnesota. Generally all hazards are on the table, but just lower probabilities of occurrence for all because we'll be generally on the northern end of favorable ingredients. Could see a few discrete cells that merge into a line in-tandem with the cold front Monday afternoon/evening, but that's all dependent on timing of the frontal passage. At this time, any severe storms will probably be on the low-end of severe, with hail and strong winds being the main threats.

We'll lose broader lift going into Tuesday, but even after the cold front, we'll still be plenty warm, so some scattered showers/storms can't be ruled out (40% chance). The rest of the week looks seasonably warm with occasional troughs bringing rain/storm chances at least in the vicinity of the Northland.
Some places may see some rain while others don't see a whole lot. It's looking like some broader ridging may move in for next weekend, which means temperatures keeping on the warm side.

AVIATION /18Z TAFS THROUGH 18Z SUNDAY/
Issued at 1248 PM CDT Sat Jun 14 2025

An area of predominantly MVFR ceilings to linger across the southernmost three terminals (KHYR, KBRD and KDLH) for most of this forecast. IFR ceilings are possible this afternoon around KHYR. MVFR visibilities may develop overnight tonight at HYR and KDLH as low-level moisture increases and fog becomes possible.
Dense fog isn't likely, but some light fog could certainly develop overnight and linger into Sunday morning. INL and HIB are expected to remain VFR through the period. Scattered showers will remain possible through much of the period for HYR and BRD.

MARINE /FOR NEAR SHORE WATERS OF WESTERN LAKE SUPERIOR/
Issued at 349 AM CDT Sat Jun 14 2025

Some breezy northeast winds are expected to persist today, generally holding their strength around the head of the lake and perhaps briefly topping out with some gusts in the 20-25 knot range and wave heights in the 3-4 ft range. Extended the Small Craft Advisory into the mid-afternoon at the head of the lake as current conditions are expected to generally remain constant through the day. This evening into Sunday, northeast winds gradually decrease and become light and variable Sunday night.

Expect some occasional rain chances (20-30%) today through Sunday. Thunder chances will be low, but non-zero (~10-20% chance Sunday).

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

DLH WATCHES/WARNINGS/ADVISORIES
MN...Beach Hazards Statement until 10 PM CDT this evening for MNZ037.
WI...Beach Hazards Statement until 10 PM CDT this evening for WIZ001.
MARINE...Small Craft Advisory until 4 PM CDT this afternoon for LSZ144- 145.