textproduct: Marquette

KEY MESSAGES

- Active weather returns this afternoon through Friday as a deepening low pressure system works through the Great Lakes bringing periods of rain and gusty N to NW winds.

- Hazardous marine weather is expected Friday. Northerly wind gusts to 50 kts are possible (25-50% chance), creating significant wave heights between 15-20 ft.

DISCUSSION

Issued at 315 AM EDT Thu Oct 15 2026

Early morning water vapor imagery shows a well-defined trough moving across the Canadian Prairie, and another midlevel low spinning over the Rockies. To the east, the midlevel ridge axis is directed right over the Great Lakes. At the surface, this all translates to surface lows currently centered over Manitoba and Oklahoma, and high pressure centered over central Ontario. Closer to home, we remain under a blanket of low clouds, though some mid and upper-level cloud cover associated with Plains convection is beginning to stream into the area amid southerly flow developing aloft. Ample cloud cover has kept temperatures several degrees warmer than expected tonight, with most of the area currently in the mid 40s and only expected to bottom out in the lower 40s and perhaps upper 30s.

Guidance continues to agree on the Canadian and Rockies features to phase near NE/SD this afternoon, with a surface low deepening to 1007-1009mb near Chicago by 00Z Friday. Warm advection out ahead of this kicks off a batch of widespread rain across the area this afternoon and evening, with this initial batch dropping widespread totals around 0.50-0.75" by 06Z. The cold front passes through the second half of the night, with 850mb temperatures eventually falling to around -5 to -7C into Friday afternoon. Thus, expect a transition over to lake effect/enhanced rain from 06Z onwards, with rain gradually becoming isolated to the northerly wind belts Friday morning and afternoon. Additional totals around 0.25-0.75" are expected, with the highest across the upsloping areas over the north- central UP and the Porcupines. Wouldn't surprise me to see some wet snow mix into areas of the interior highlands early and then late Friday as freezing levels fall to ~1000 ft AGL, but no accumulations are expected.

Meanwhile, Friday morning through Fri afternoon the surface low feature deepens while departing northeast atop the Lower Lakes, placing Upper Michigan on the northwestern flank. Strong cold air advection and stout pressure rises (upwards of 1-2mb/hr) will contribute to northerly wind speeds reaching 25-35 kts gusting 45-50 kts on Lake Superior and the adjacent lakeshores. There is still some uncertainty regarding the maximum gust potential as ensembles (NBM and ENS) have decreased the probability of Storm Force gusts in the central lake (20-50% chance) and model soundings don't highlight mixing into any 50 kts gust layers.

As winds settle late Friday and dry high pressure clears skies from west to east, temperatures will drop like a rock overnight into Saturday morning, reaching the mid to low 20s for much if not all of the interior while some lakeshores may reach freezing for the first time this fall. Ridging and dry weather dominate through the rest of the weekend with the potential for another warm up / fire weather pattern Sunday into Monday. Similar to last weekend's fire weather setup, ensembles suggest a 50-75% chance for S to SW winds gusting to 35 mph in the typical downslope locations of the west and central UP and minimum RHs falling to near 30% in the interior west and central. Luckily, temperatures are only slated to peak into the 60s. Fire partners and adjacent parties should continue to monitor the forecast as containment and mop up efforts for ongoing wildfires may still be ongoing.

AVIATION /06Z TAFS THROUGH 06Z FRIDAY/

Issued at 109 AM EDT Thu Oct 15 2026

Low end VFR to MVFR cigs persist this morning accompanied by calm conditions as high pressure passes overhead. Deterioration down to IFR is expected with rain this afternoon as another system moves in from the west. Expect rain to arrive at IWD around 16Z, followed by CMX at 19Z, and SAW at around 21Z. Although periods of LIFR can't be ruled out at IWD/CMX, mention was only added to SAW for now as exact timing and duration remains uncertain in the western UP.

MARINE

Issued at 315 AM EDT Thu Oct 15 2026

Lake Superior: Light southeast winds early this morning shift southerly into the daytime, gusting to around 15-20kts ahead of a strong cold front tonight into Friday morning. This strong cold front accompanies a deepening low pressure system that works through the Lower Great Lakes on Friday. Strong cold advection and rapid pressure rises will create sustained winds near gale force with gusts reaching 40-50 kts in the central lake Friday morning. Gales of 35-45kts are expected elsewhere across the lake. Significant wave heights build between 15-20 feet, highest along the southern lakeshores. Winds and waves slowly subside lake into early Saturday. A Gale Warning is in effect for the entire lake on Friday. Winds briefly fall back Friday night while shifting over to the SW, but then SW gales will be possible across the western arm of the lake as early as 12Z Saturday (50% chance), lingering through Sunday before winds quickly fall back below 20kts into Monday.

Northern Green Bay and northwestern Lake Michigan: Light easterly winds turn more to the southeast after daybreak, ahead of a strong cold front that whips through the northern bay and lake late tonight to early Friday. Northwest winds quickly ramp up between 35-40 kts Friday with waves building between 5-8 ft. Winds and waves subside below gale force Friday night. A Gale Warning is in effect for all N Lake Michigan marine zones on Friday. Winds briefly fall back below 20kts early Saturday morning while shifting to the SW, but then gusts pick up to 20-25kts into the afternoon with gales possible by early Sunday (50% chance). Winds quickly fall back below 20kts into Monday.

MQT WATCHES/WARNINGS/ADVISORIES

Upper Michigan... None. Lake Superior... Gale Watch from late tonight through Friday afternoon for LSZ162-240>242-263.

Gale Watch from late tonight through Friday afternoon for LSZ243-244-264.

Gale Watch from Friday morning through Friday evening for LSZ245>251-265>267.

Lake Michigan... Gale Watch from Friday morning through Friday evening for LMZ221-248-250.