textproduct: Marquette

KEY MESSAGES

- Gusty winds to 45 mph in the Keweenaw and 25-35 mph elsewhere will diminish this evening.

- A Gale Warning remains in effect for most of Lake Superior through this evening for gales to 35-40 knots.

- Dry weather continues through the end of the week with highs in the low to mid-70s Thursday and near 80 Friday.

DISCUSSION

Issued at 156 PM EDT Wed Sep 9 2026

Early afternoon water vapor imagery and RAP analysis shows a dry airmass spreading across the UP amid broad troughing, while a sharper trough is rotating west to east across Ontario. At the surface, an unseasonably strong, 980 mb low (1 percentile of climo) is located over southern Hudson Bay. Strong low-level height gradient associated with this circulation resulting in 30-40 kt westerlies at 850 mb combined with deep mixing is promoting a breezy day, especially across the Keweenaw which is closer to the 850 mb wind core. 35-40 kt wind gusts will be common there the remainder of today, with 25-30 kt elsewhere.

Ridging and a dry airmass (PWATs falling to below 0.75 in) promote a cooler night tonight with lows near normal in the mid-40s to mid- 50s. Remaining seasonable and clear on Thursday with highs in the low to mid-70s.

Seasonably strong 500 mb zonal flow evolves Fri/Sat over the northern tier of the western half of the CONUS. A lead shortwave trough ejecting across the Upper Midwest will foster a compact surface low/front over the northern Plains, near which convection is expected to erupt Friday afternoon/evening within a plume of moderate instability. Southerly flow ahead of this surface feature will promote a warm and dry day Friday with highs around 80. The front sweeps across the UP Friday night with rain and thunderstorms expected for the west half, weakening with eastward extent along with the instability. Severe weather is not expected at this time due to the waning instability. It will be more seasonable and dry behind the front on Saturday and likely into Sunday.

Looking ahead into early next week, there are indications that a wetter pattern evolves as a Colorado low develops in response to deep troughing over the northern Rockies. Good poleward Gulf moisture advection is modeled (mean PWATs in the 1.5-1.75 inch range locally per the LREF, which is toward the 95 pctl of climo), which will be lifted atop a low-level frontal boundary to provide a potentially long-lived period of rainfall Monday into Tuesday in the Upper Midwest. Cluster analysis shows the main mode of variability is tied to the overall amplification of the encroaching trough and downstream ridge, with a more (less) amplified height field favoring a wetter (drier) solution. About a quarter of the LREF members are slower with the trough, which would favor another dry day on Monday, as well. Regardless, LREF indicates a 50-60% chance of accumulating 1" of rainfall by Tuesday evening, and a 20-30% chance of 2". Medium range AI-based convective hazards forecasts indicate any severe weather risk remains to our south during this period.

AVIATION /18Z TAFS THROUGH 18Z THURSDAY/

Issued at 129 PM EDT Wed Sep 9 2026

VFR conditions prevail under the dry slot of a deepening low in northern Ontario. The main aviation concerns remain strong westerlies gusting 20-40 kts (strongest at CMX) this afternoon and evening. As the pressure gradient slackens tonight, winds slowly fall below 20-25 kts area wide though breezy N-NW winds 15-20 kts may linger at CMX the longest. By tomorrow morning, winds will be <15 kts at all sites. VFR conditions persist with winds becoming more dominated by lake and land breeze circulations.

MARINE

Issued at 156 PM EDT Wed Sep 9 2026

Lake Superior: Gale warnings remain in effect this afternoon, ending from west to east this evening. So far, available obs have showed winds coming up a bit short of forecasts, likely due to the lack of enough cool air aloft to promote efficient mixing. Still, there is potential for gusts of 35-40 kt through this evening, especially around the Keweenaw to the east-central portion of the lake. Significant wave heights of 7-11 feet will be common here. Winds diminish late tonight into Thursday, but increase again from the south to southwest Thursday night into Friday night, approaching 30 kt at times.

Northern Green Bay and northwestern Lake Michigan: A Small Craft Advisory remains in effect through 8 pm EDT for westerly wind gusts to near 25 kt. Winds diminish tonight into Thursday, but increase again from the south to southwest on Friday, with gusts around 25 kt and waves building to 4-5 feet Friday into Saturday.

MQT WATCHES/WARNINGS/ADVISORIES

Upper Michigan... Beach Hazards Statement until 10 PM EDT this evening for MIZ006.

Lake Superior... Gale Warning until 6 PM EDT /5 PM CDT/ this evening for LSZ162.

Gale Warning until 10 PM EDT /9 PM CDT/ this evening for LSZ240>244-263-264.

Gale Warning until midnight EDT tonight for LSZ245>248-265-266.

Gale Warning until 2 AM EDT Thursday for LSZ249>251-267.

Lake Michigan... None.