textproduct: Marquette

KEY MESSAGES

- Potentially historic blizzard continues through Monday night. This will create treacherous and potentially life-threatening travel conditions and may cause tree damage and power outages!

- Additional snow amounts of 1-3 feet are expected with wind speeds of 40-65 mph. Strongest winds are expected tonight into Monday in the Keweenaw Peninsula and along the eastern Great Lakes lakeshores.

- Widespread northeast gales over Lake Superior become northerly storm force gusts of 50-60 knots tonight into Monday. There is a 30% chance for gusts exceeding 64 knots in the east on Monday. Heavy freezing spray will also occur over ice-free areas.

- Large waves on the Great Lakes increase the risk of breaking up previously-stable ice as well as the risk for beach erosion and lakeshore flooding for all Lake Superior lakeshores tonight and Monday.

DISCUSSION

Issued at 348 PM EDT Sun Mar 15 2026

The focus of the forecast discussion remains on the short term as a potentially historic, record-breaking blizzard impacts the Upper Great Lakes through Monday night. The prolonged nature of very strong winds and quickly accumulating, blowing, and drifting snow continue to make travel conditions treacherous and potentially life- threatening as well and likely result in power outages into early next week. Travel should be restricted to emergencies only through Monday as even emergency vehicles will struggle to navigate the roads at times!

Afternoon GOES water vapor imagery and RAP analysis show the mid level trough has dug into the east edge of the Plains. Beneath it, the surface low pressure has reached northern IL at around 992 mb. Robust f-gen set up from southern WI over northern Lake MI alongside favorable jet dynamics and isentropic ascent is resulting in the busy radar mosaic across the region. Reflectivities of 20-30 dZB indicate heavy snowfall rates of 1-3 in/hr across much of the UP, highest over the east; lower rates around 0.5-1.5 in/hr are more common over the far west. These rates remain elevated, but decrease to 0.5-1.5 in/hr this evening as the upper jet right entrance region departs and the isentropic component ends. Some of the CAMs even indicate a dry slot attempting into the interior west, but measurable snow is not expected to end for very long if at all...mostly looking at a lull in significant accumulation. Meanwhile, winds will continue to ramp up as the pressure gradient tightens and a strong 60-70 kt LLJ sets up on the north side of the low.

The mid level wave takes on a slight negative tilt tonight and Monday, pivoting strong vorticity advection over the Upper Great Lakes. This deepens the surface low to near 980 mb as it tracks from around Chicago northeast over Lower MI tonight, reaching northern Lake Huron by mid to late Monday morning. Model soundings show some variability of how far the LLJ reaches into the mixed layer, but very strong winds are expected regardless of peak winds near or just above the inversion given good consensus on a strong overall wind field. The pivoting mid level wave will revamp synoptic forcing for snow late tonight into Monday as well delta-Ts increasing the lake enhancement. Heavy snowfall rates of 0.5-2 in/hr are expected, especially in areas with northerly upslope flow Monday morning.

The high winds will peak late tonight into Monday morning. With the close proximity the LLJ has to the surface, interior winds are expected to increase overnight to 20-35 mph with gusts up to 35-55 mph. Even stronger winds are expected in the Keweenaw, near Lake Superior (particularly eastern shores), and in the vicinity of the Garden Peninsula; winds Monday morning of 20-40 mph with gusts of 40- 65 mph are expected in those areas! Model soundings indicate even higher gust potential and probabilistic guidance backs this up. HREF probabilities of gusts exceeding 65 mph are generally between 30-60% in the central and east, highest in Marquette/Delta Counties as well as eastern Lake Superior shores. While probabilistic guidance begins to drop off after this magnitude, model soundings at least show that isolated gusts exceeding 70 mph can't be ruled out (15-30% chance). Should these higher winds occur, tree damage and power outages should be expected. Widespread 1/4 or lower visibilities to whiteout conditions are expected when these winds combine with the uptick in snow. Expect significant snow drifts several feet tall, adding to difficult travel and snow load on structures. The strong winds over Lake Superior build wave heights of up to 20-30 ft, highest over the central third of the lake. Lakeshore Flood Warnings and a Lakeshore Flood Advisory remain tonight and Monday as a result.

With 850 mb temps lowering further on Monday to -22C to -24C, trailing LES showers over the north becoming northwest wind snowbelts continue Monday night into Tuesday as the low lifts to Quebec. Despite model soundings indicating a deep DGZ up to 10 kft at times, latest observations at the start of this event have been lower than forecast (ranging 6:1 and 10:1). Strong winds will be a limiting factor in SLRs tonight and Monday. Even when lowering SLRs from the NBM, the broad QPF field across the CWA between 1-2 inches yields additional snow amounts in feet. 1-3 feet of additional snow through Monday night is expected, highest north- central and east. With the forecast generally on track and the wind threat slightly increasing for tonight into Monday, maintained the Blizzard Warnings as is.

Otherwise temps move from the mid 20s to near freezing this afternoon to single digits above to mid teens tonight. Highs on Monday will be colder in the teens to low 20s, settling further Monday night into the single digits mostly above 0. With the cold air and strong winds, wind chills will be in the single digits to negative teens, coldest Tuesday morning. LES drops off from west to east on Tuesday as high pressure moving in from the west shifts winds west to southwest and ushers in drier and warmer air. Any additional accumulations during the day Tuesday will be limited to 1 inch.

The rest of the forecast brings snow chances (30-60%) with a clipper system, but accumulations would be light. The pattern favors a warm up late in the week with highs returning to the 30s and 40s with lows in the 20s.

AVIATION /00Z TAFS THROUGH 00Z TUESDAY/

Issued at 748 PM EDT Sun Mar 15 2026

A powerful winter storm continues to impact Upper Michigan terminals this evening with IFR/LIFR conditions in moderate to heavy snow and blowing snow. Expect cigs to trend more predominantly MVFR during a bit of a lull in snowfall rates this evening, but increasing winds will maintain IFR/LIFR vis with BLSN as the strengthening surface low moves closer to the region. Winds will continue to increase overnight, potentially reaching 45-50 kt at KCMX/KSAW and near 40kts at KIWD. Snowfall will also pick back up in intensity by early Monday morning and promote continued IFR/LIFR conditions through most of the day. Winds will start to trend down but still remain strong in the 35-40 kt range through 00z Tue.

MARINE

Issued at 408 PM EDT Sun Mar 15 2026

A strong to historic storm moves from southwest to northeast over the Upper Great Lakes today through Monday. Northeast gales continue to increase through tonight to storm-force 50-60 kts, strongest over the east. Guidance continues to hold a low (15-30%) chance for hurricane-force winds Monday morning over the east half of the lake, particularly along the southern shores. In addition to the strong winds driving significant wave heights of 20+ ft (some to near 30 ft between Stannard Rock and the shores of Marquette and Alger Counties), cold air descending overhead will result in heavy freezing spray. As the low exits towards Quebec, winds diminish Monday night, falling below storms around midnight and below gales lakewide Tuesday morning.

For the remainder of the week, the weather pattern favors one or two weaker clipper systems moving north of Lake Superior between Wednesday and late Friday. The pattern also favors warm, southerly flow, reducing the risk of heavy freezing spray. Gale chances are low (10-40% chance), highest probabilities with the late week system.

MQT WATCHES/WARNINGS/ADVISORIES

Upper Michigan... Blizzard Warning until 2 AM EDT Tuesday for MIZ001-003>005.

Lakeshore Flood Warning until 11 PM EDT Monday for MIZ001-003.

Blizzard Warning until 8 PM EDT /7 PM CDT/ Monday for MIZ002- 009>012-084.

Lakeshore Flood Warning from 11 PM this evening to 5 PM EDT Monday for MIZ002.

Lakeshore Flood Warning until 2 AM EDT Tuesday for MIZ005.

Blizzard Warning until 8 AM EDT Tuesday for MIZ006-007-013-014- 085.

Lakeshore Flood Warning until 8 AM EDT Tuesday for MIZ006.

Lakeshore Flood Warning from 5 AM Monday to 2 AM EDT Tuesday for MIZ007.

Lakeshore Flood Advisory from 10 PM this evening to 4 PM CDT Monday for MIZ009.

Lake Superior... Gale Warning until 8 PM EDT /7 PM CDT/ this evening for LSZ162- 240>251-263>267.

Heavy Freezing Spray Warning until 2 AM EDT /1 AM CDT/ Tuesday for LSZ162.

Storm Warning until 11 AM EDT /10 AM CDT/ Monday for LSZ162.

Heavy Freezing Spray Warning until 2 PM EDT /1 PM CDT/ Tuesday for LSZ240>248-263>265.

Storm Warning until 2 PM EDT /1 PM CDT/ Monday for LSZ240>242- 263.

Storm Warning until 2 AM EDT Tuesday for LSZ243>251-264>267.

Heavy Freezing Spray Warning until 5 PM EDT Tuesday for LSZ249>251-266-267.

Lake Michigan... Gale Warning until 8 PM EDT this evening for LMZ248-250.

Storm Warning until 4 PM EDT Monday for LMZ248-250.

Heavy Freezing Spray Warning from 2 AM Monday to 2 AM EDT Tuesday for LMZ248-250.