textproduct: Marquette

KEY MESSAGES

- Lake effect snow and blowing snow will result in reduced visibility and locally difficult traveling conditions today in the Keweenaw and the eastern UP, especially east of Munising and along and north of M-28.

- After a mild day on Friday, a strong cold front on Friday night will bring much colder air back into the area along with a period of strong winds, particularly over the Keweenaw and near Lake Superior, where there is a 60% probability of wind gusts exceeding 45 miles per hour. Areas of blowing snow may restrict visibility in open areas.

DISCUSSION

Issued at 227 AM EST Wed Feb 25 2026

Compact midlevel closed low located over central Ontario early this morning, with deep moisture axis associated with yesterday's light snow well to the east. Subtle shortwave trough along the southern periphery of this low heralding a cold advection push is now pushing through the UP. Subtle forcing with this wave, along with moisture in the surface to 700 mb layer wrapping around the low (as evidenced by the all-layer precipitable water product and suggested by upstream light radar returns), is resulting in an area of light snow over much of the UP, which could result in very light accumulations in the predawn hours. We will trend toward a more typical northwest flow lake effect setup later this morning as moisture above 850 mb gradually exits to the east. Convective layer becomes established within the DGZ as 850 mb temps fall to around -20C, which will lead to a fluffy snow that is prone to blowing. Although snowfall amounts will be modest, locally difficult travel conditions are expected due to blowing snow with northwest wind gusts to around 25 kt. Lake effect parameters are relatively better in the east today with inversion heights around 2km, and the most prevalent bands are expected along/north of M-28 east of Munising, where snowfall rates in the heaviest bands likely exceed half an inch per hour. Elsewhere, it will be a seasonably chilly day with temps not rising much from morning readings in the low teens west to low 20s east.

On Thursday, a similar pattern to the one seen yesterday will evolve, with a northern stream jet max punching into the upper Mississippi Valley, providing lift from poleward exit region dynamics as well as preceding isentropic lift. Overall this system is less dynamic than the last without much moisture to work with, so snowfall amounts will be light at around an inch or less. In the wake of this system, a warm sector will spread into the UP on Friday as a strong, compact low moves eastward across Ontario (ensemble means have it in the mid-upper 980s mb range). This should result in the mildest day we've seen since about Feb. 16, with highs from the upper 30s (east) to mid-40s (west).

As the low continues strengthening as it moves into James Bay Friday night, it will send a strong cold front across the UP. LREF mean 925 mb winds are 35-45 kt (highest north), and model soundings suggest a few hours where mixing into this layer is expected. Current probs for 45 mph (wind advisory criteria) gusts in the Keweenaw and along the Lake Superior shoreline are around 60 percent, and a brief gust to 58 mph (high wind warning criteria) can't be ruled out in the Keweenaw (20% chance). EFI shows wind gust values in excess of 0.8 here, implying unusually strong winds, albeit for a fairly brief window Friday evening/night. This could cause some visibility issues due to blowing snow in open areas, although the threat is mitigated by the fact that the front is unlikely to be accompanied by snowfall.

Arctic airmass will reside over the local area during the weekend, with NAEFS mean forecasting 850 mb temps of -20 to -25C, -1 to -2 sigma. While the probability of Cold Weather Advisory criteria is less than 20% at this time, we will still likely see apparent temps bottoming out in the negative single digits and teens Saturday, Sunday, and Monday mornings. Light lake effect snow in the NW belts could result in visibility issues as well due to fine flakes on Saturday and perhaps Sunday.

AVIATION /12Z TAFS THROUGH 12Z THURSDAY/

Issued at 602 AM EST Wed Feb 25 2026

NW lake effect snow showers continue through most of the period, although they do look to cease over IWD and potentially even CMX by tonight as another shortwave approaches the area heading into Thursday morning. As of this morning, the terminals are ranging from IFR to VFR conditions, with vis potentially having the potential to get down to 1 mile or less at IWD and CMX today (up to a 10% and 20% chance, respectively). As some diurnal mixing comes into play, we could see SAW have cigs drop down into MVFR this afternoon before improving back up to VFR this evening. As the gusty NW winds progressively die-down today, expect the the BLSN threat over CMX (and to a lesser extent IWD) to dwindle with time. By late this afternoon, thinking the lake effect cloud deck over IWD will scatter out and bring VFR conditions back over the terminal; as for CMX, thinking they will most likely remain under MVFR at least until late tonight. Could see the shortwave coming in on Thursday lower conditions at CMX and IWD at the end of the TAF period once again as -SN returns.

MARINE

Issued at 234 AM EST Wed Feb 25 2026

A period of northwesterly gales is expected over the east central part of the lake this morning as colder air spreads over the lake, with a few gusts to gale force possible in the west. Heavy freezing spray will accompany the winds as well. A ridge of high pressure will build in Wednesday night into Thursday with northwest winds falling below 20 kt and shifting southwest. Southwesterly winds will ramp up to 30 kt on Friday ahead of a deepening clipper low that will move through Ontario Friday night. A strong arctic cold front associated with the low will move across the lake Friday evening. Behind the front high end gales are expected over at least the eastern two thirds of the lake (90% chance) with a 50% chance for storm force gusts. Heavy freezing spray will also accompany the winds. Winds will diminish through the day on Saturday with light winds on Sunday as a strong high pressure moves overhead.

MQT WATCHES/WARNINGS/ADVISORIES

Upper Michigan... Winter Weather Advisory until 7 PM EST this evening for MIZ001- 003-006-007-085.

Lake Superior... Heavy Freezing Spray Warning until 7 AM EST /6 AM CST/ this morning for LSZ162.

Heavy Freezing Spray Warning until 10 AM EST this morning for LSZ242-263.

Heavy Freezing Spray Warning until 4 PM EST this afternoon for LSZ243>248-264-265.

Heavy Freezing Spray Warning until 1 AM EST Thursday for LSZ249>251-266-267.

Gale Warning until 1 PM EST this afternoon for LSZ265-266.

Lake Michigan... None.