textproduct: Marquette

KEY MESSAGES

- Widespread 25 to 35 mph southwesterly wind gusts expected today. Wind gusts near 45 mph possible in and near Marquette this morning.

- Southwesterly gales are likely today over western and central Lake Superior, including by the central Upper Michigan lakeshore.

- Dry weather expected through at least the first half of next week.

DISCUSSION

Issued at 129 AM EDT Sun Oct 18 2026

GOES 19 Water Vapor and IR imagery position Upper Michigan on the forward face of a large mid-upper level ridge stretching across central CONUS, north of a stout 1031mb surface high over the Ohio Valley, and to the southeast of a 986mb low over northern Saskatchewan. This translates to the forecast area being within southwest gradient flow under a mild and dry airmass. At the time of this publishing, dewpoint depressions were observed at 20-25F over much of the region, yielding RH values of 35-50% in many interior west locations, temperatures in the 40s and 50s, and 15-20 mph occasional wind gusts. Outside of this high clouds have been observed moving through the region from the northwest. For the remainder of the overnight period, anticipated additional cooling should occur, but given the rate of cooling observed so far, suspect overnight lows may remain in the 40s for many locations. This will help overnight RH recoveries, but suspect many locations will remain below 50-60%. Southwest flow is expected to continue with the overheard 925-850mb 40-50kt LLJ expanding in coverage over the region, potentially resulting in more frequent wind gusts near 20 mph over the west half of Upper Michigan.

Today, the forecast area will remain positioned between the surface high to the south and east and the surface low to the north. This will support continued warm, dry, and breezy conditions for the forecast area. Model soundings highlight mixing deep enough to tap into elevated dry air and stronger winds aloft, likely supporting RH values falling into the 30s for many locations and widespread 25-35 mph southwest wind gusts. The HREF, REFS, and NBM highlight 45mph or greater potential along the lakeshores near Eagle Harbor and the Michigamme highlands. Notably, both the HREF and REFS focus a swath of this potential in the downslope regions of Marquette County, with an ideal cross terrain flow which would indicate an potential adiabatic acceleration down into the city of Marquette. Given the perpendicular flow to the terrain, favorable HRRR model soundings for mixing, a core of ~50kts near 925mb, and current KMQT VAD profiles indicating 40-50kts at 1000ft, opted to issue a Wind Advisory for Marquette County for this morning.

Winds will lighten late this afternoon and evening, then continue to remain light through at least Wednesday morning thanks to another strong surface high migrating across the northern Plains toward eastern North America. Daytime highs peaking in the mid 60s for most interior locations and closer to 60F lakeside is expected each day for the coming week, with maybe upper 50s in the Keweenaw. Overnight lows most nights in the 30s should be expected inland, with 40s by the lakeshores. The next system moving within the proximity of the Great Lakes is Wednesday, but latest models have trended drier for our forecast area. This results in the next best shot of rain coming next weekend.

AVIATION /06Z TAFS THROUGH 06Z MONDAY/

Issued at 126 AM EDT Sun Oct 18 2026

Low level wind shear will continue to impact all terminals through 13-16z Sun as a strong low level jet crossing Upper Michigan brings southwest winds of 45-50 kt at FL015-020. Winds become gusty again at the surface after sunrise and persist through Sun afternoon, finally starting to diminish this evening. Otherwise, other than ongoing wind concerns, expect VFR conditions under mostly clear skies through the period.

MARINE

Issued at 129 AM EDT Sun Oct 18 2026

Lake Superior: Southwest flow has been observed over Lake Superior, with highest observations so far being 20-34kts across the west half and along the lakeshores where the southwest flow is perpendicular to nearby terrain. Increasing 925-850mb LLJ is anticipated over the next few hours, resulting in increased gale potential and additional coverage of these elevated winds. Not confident about how much of the core of elevated winds will mix to the surface in the open lake, but confidence in occasional wind gusts to 40kts is high enough to maintain the inherited Gale Warnings across the west half of the lake for today. I did opt to expand Gale Warnings to the open lake zone just east of the Keweenaw and nearshore waters from Big Bay to Munising given an improved signal for adiabatic warming/acceleration with cross perpendicular flow into these waters this morning. Confidence is low in how far offshore the gale potential will end, but SAR imagery of past similar downsloping wind events tend to include gales ending 5-10nm into the lake. Winds are expected to lighten late this afternoon/evening, then continue falling overnight. Near midnight, winds lake-wide may be below 20kts followed by these light winds continuing for a majority of the coming week.

Northern Green Bay and northwestern Lake Michigan: Southwest winds range from 5 to 30kts at observation sites in and surrounding these waters. Additional warm air advection aloft overnight and this morning with an enhanced LLJ will continue potential for elevated winds to 30-35kts, especially this morning. Given these waters are currently observed near 15C, per GLERL analysis, and the warming 850mb airmass, opted not to upgrade Small Craft Advisories to Gale for the Bay, but did move up the start time of the inherited Gales for the Lake Michigan waters to starting immediately. Tonight, winds will lighten below 20kts. By Monday, high pressure influence over the region will likely support <15kt winds through at least Wednesday.

MQT WATCHES/WARNINGS/ADVISORIES

Upper Michigan... Wind Advisory from 8 AM this morning to 2 PM EDT this afternoon for MIZ005.

Lake Superior... Gale Warning until 2 PM EDT /1 PM CDT/ this afternoon for LSZ162.

Gale Warning until 5 PM EDT this afternoon for LSZ243-244-263- 264.

Gale Warning from 8 AM this morning to 2 PM EDT this afternoon for LSZ245>249-265.

Lake Michigan... Gale Warning until 11 PM EDT this evening for LMZ248-250.