textproduct: Marquette

KEY MESSAGES

- Breezy today through Sunday, especially along the Keweenaw and near Lake Superior. Northwest gales to around 35 knots are expected over central/eastern Lake Superior this afternoon through Sunday.

- Lake effect snow showers return to the northwest wind snowbelts tonight into Sunday morning and continue through early next week, mainly in the eastern UP.

- Confidence is increasing that dominant lake effect snowbands will provide impactful snowfall to portions of Luce, Chippewa, and Mackinac counties. A Winter Weather Advisory has been issued for these counties tonight through Monday morning.

DISCUSSION

Issued at 302 PM EST Sat Nov 15 2025

Afternoon GOES satellite imagery reveals mostly clear skies overhead the UP and Lake Superior as a ~992 mb sfc low north of Lake Huron continues its eastward journey through Ontario. Strong cold air advection behind the surface cold front has increased NW flow across the area, supporting gusts 20-30 mph inland and 30 to 40 mph in the Keweenaw and Lake Superior shorelines. Despite the passing sfc cold front, daytime temps have managed to punch into the low to even mid 50s this afternoon. Temperatures tonight begin to drop to the upper 20s.

As Upper Michigan becomes placed between troughing overhead the Atlantic and a building ridge in the High Plains, continued chilly NW flow will help 850 mb temperatures begin to fall tonight through Sunday, reaching roughly -9 to -11C by tomorrow afternoon. This will support an increase in lake effect snow across the NW wind snowbelts late tonight. Model soundings depict notable dry air within the DGZ and sub-cloud layer in the western half of the UP, thus shutting off lake effect snow potential. In the east, the long NW fetch across Lake Superior and potentially Lake Nipigon preconditioning is slated to kick off lake effect snow bands from Munising eastward. There is good CAM agreement in a dominant lake effect snow band with lake induced inversion heights upwards of 7-10 kft persisting in the vicinity of Luce/Chip counties through Monday. However, there is some question about weather antecedent dry air, both sub-cloud and within the DGZ, may limit snowfall rates. The latest HREF supports this idea, suggesting low probabilities (<25%) chance for 1"/hr rates. 6hr QPF amounts 0.1-0.2" coupled with SLRs near 15:1 result in 6 hourly snowfall amounts in Luce/Chip co around 1-3" from tomorrow morning through Monday morning, totaling ~2-7", with the greatest snowfall amounts closer to the Luce/Chip SE border. This bullseye can easily shift depending on the band's convergence into the eastern UP. For these reasons, opting to hoist a Winter Weather Advisory for Luce County (Chippewa and Mackinac counties included by neighboring WFO APX) from midnight tonight through Monday morning. If sublimation via dry air is overcome by lake moisture and persistent dominant banding in one area, would not be surprised to see locally higher amounts. Additionally, gusty winds 30-40 mph, strongest near the lake, under strong lake effect snowbands will drastically reduce visibility at times, so take it slow should you encounter these conditions.

Lake effect snow briefly shifts west into Alger/Schoolcraft Co early Monday before tapering off as sfc high pressure overhead supports drier air advection, lowering lake inversion heights and reducing wind speeds through the column. Heading into the rest of the workweek, benign low impact weather remains in the forecast. Zonal flow aloft supports more moderating temps in the upper 30s and low 40s. Global forecast guidance suggests a weak shortwave skirting south of the UP late Tuesday, keeping synoptic precip out of the area. High pressure dominates through the midweek. The next shot at reasonable precipitation returns this coming weekend, though at this time confidence is low as long range guidance is still coming into agreement on the placement and strength of a low moving through the Lower Lakes Friday.

AVIATION /18Z TAFS THROUGH 18Z MONDAY/

Issued at 549 PM EST Sat Nov 15 2025

VFR cigs are expected to hold across the terminals tonight and Sunday. However, as lake-effect cloud cover sets up over the area, expect to see low-end VFR cigs take hold late tonight through Sunday morning, with a few snow flurries being possible across CMX and SAW late tonight into Sunday morning. Given the cold air advection that's ongoing and will continue through the next 24 hours, expect gusty NW winds through the TAF period, although the gustier winds aloft may struggle to reach the sfc from time to time early this evening. Chances for MVFR cigs are lower than in the previous forecast package, now ranging from 15 to 25% amongst the terminals.

MARINE

Issued at 302 PM EST Sat Nov 15 2025

Impactful marine weather remains in the forecast as chilly NW flow carries Gales of 35-40 kts through tomorrow. NW gales 35-40 kts have already been seen across the east and central lake with a few high based platforms observing 40-45 kts. guidance continues to suggest this will be common through the rest of today before a brief lull early tomorrow morning. A reinforced shot of cold air will then again continue NW gales through Sunday evening before tapering down below 35 kts across the east half of the lake by Midnight on Monday. Significant wave heights will build between 7 and 13 feet, with the highest waves seen along the eastern UP shorelines tonight. Waves begin to lessen below 7-10 feet early Monday. Additionally, while widespread Gales are not expected in the west half of the lake, a Gale Warning has been introduced for the north shores of Lake Superior between Grand Portage and Taconite Harbor where winds running down the terrain may accelerate to Gale force gusts of 35 kts tonight.

MQT WATCHES/WARNINGS/ADVISORIES

Upper Michigan... Winter Weather Advisory from midnight tonight to 7 AM EST Monday for MIZ007.

Lake Superior... Gale Warning until 7 PM EST Sunday for LSZ249>251-266-267.

Gale Warning until 10 AM EST Sunday for LSZ265.

Lake Michigan... None.