textproduct: Marquette

KEY MESSAGES

- Gusty southwest to westerly winds of 25 to 40 mph are expected late tonight and Sunday. The strongest winds are expected in the Keweenaw and north-central Upper Michigan.

- Daytime temperatures Sunday and Monday will be 10 to 20 degrees above normal, peaking in the 50s in some locations. Above freezing temperatures Sunday night will be 25 to 30 degrees above normal.

- Widespread snowfall is expected late Tuesday through Wednesday, with lake effect snow trailing downwind of Lake Superior Wednesday night.

- Another widespread snowfall event may impact the U.P. Thursday night and Friday.

DISCUSSION

Issued at 134 PM EST Sat Mar 7 2026

Latest GOES Water Vapor imagery and RAP analysis show a surface low just east of Lake Superior in Quebec with a cold front extending northeast to southwest just to its west. Within this, a plume of deep moisture associated with last night's rain and thunderstorms has been observed slowly exiting the region while a post frontal swath of rain and snow has been slowly moving through western Upper Michigan with preceding convectively looking showers in central Upper Michigan closer to the front. This resulted in a mix of rain, freezing rain, and wet snow. Various webcams in the Keweenaw showed snow covered roadways this morning when snowfall was heaviest. Since then though, precip has shown signs of diminishing as the parent mid- level shortwave has moved into western Lake Superior and surface ridging has helped increase subsidence. Surface temperatures have mostly hovered in the 30s across the region with the coolest temperatures closer to 30 being observed in the west where 850mb temps have fallen to near -6C, per SPC mesoanalysis. Road surface temperatures climbing into the upper 30s and 40s so far today have also been observed. For the remainder of the afternoon, precip will end from west to east and skies are expected to begin clearing thereafter. Little to no warming is expected.

Tonight into Sunday, weak surface ridge will exit as a deepening surface low moves through Ontario and its shortwave and surface trough move through west to east Sunday morning. Increasing 50kt LLJ near 900mb late tonight will support increasing southwesterly flow ahead of the trough before it begins weakening to near 40kts and shifting westerly behind the trough. With these strong winds located not far off the surface, widespread 20-30 mph winds should be expected, with winds 30-40 mph in the Keweenaw tonight. NBM suggests ~30% chance of winds exceeding 45 mph north of Houghton by Sunday morning. Will hold off on a Wind Advisory given these lower probabilities and give the next forecast team a second look. These strong winds continue into Sunday, now more westerly, as a stronger surface pressure gradient and daytime mixing continue overhead behind the trough. Expect lightening winds by evening, but another low pressure skirts the northern edge of Lake Superior Sunday night, supporting continued elevated winds from the southwest. Generally speaking, winds should be lighter Sunday night into Monday than the night before, but the Keweenaw and lakeshores can still expect 30-35 mph at times. The southwest flow will also support seasonally, very warm conditions across the region, on the order of 10 to 20 degrees above normal during daylight hours and near 30 degrees above normal for overnight temperatures. Widespread mid to upper 40s to mid 50s are suggested by the deterministic NBM both Sunday and Monday with sunday night lows potentially only bottoming out near 40F in the south-central and mid 30s elsewhere.

Tuesday into Thursday, surface high will transit northern Ontario while a weakening surface low moves through the Northern Plains and a second surface low organizes and lifts out of the Southern Plains. Preceding swath of isentropically forced snow associated with the fizzling northern stream's surface low will stretch across the region Tuesday afternoon into Tuesday night as the two features begin phasing. By Wednesday, the remaining surface low will lift northeast through lower Michigan, with its inverted trough/deformation axis stretching northwestward into the Upper Great Lakes under the support of left exit jet dynamics tied to a 150kt jet streak near 300mb. The 850mb airmass looks to slowly cool through this transition, reaching near -7C Wednesday morning, with additional cooling to near -13C Wednesday night. This will help reinforce snowfall Wednesday afternoon/evening with a possible lake enhanced component, under northerly flow, before transitioning to lake effect overnight downwind of Lake Superior into the traditional northwest wind snowbelts. Hazards with this event will include the potential for light to moderate, wet snow, becoming fluffier through the day Wednesday. Snowfall amounts are uncertain given continued uncertainty in the position on the resulting surface low. Latest NBM suggests a ~25% chance of 2 inches per 6 hours in the west half until Wednesday afternoon/night when probabilities increase to near 35-40% central and east. This generally matches the deterministic and ensemble GFS and EC. These three guidance packages suggests around 50-60% of storm total values above 6 inches during the event, with highest values in the high terrain, east, and downwind of Lake Superior.

There's timing differences between the GFS and EC on when the next high will spread its influence on the region, which will impact when lake effect ends. At this point, it looks more favorable for lake effect to end from west to east late Wednesday night/Thursday morning, but this could be delayed into Thursday evening. Lake effect snow amounts are more uncertain at this time, but the airmass and GFS model soundings suggests a few hours of ideal dendritic snow growth residence time.

Active pattern continues across the Upper Great Lakes afterwards, with another deepening surface low transiting the region Friday/Saturday. Much like the earlier system, there's positional uncertainty, which leads to lower confidence in impacts. However, another widespread moderate snowfall and windy event is plausible for Friday.

AVIATION /18Z TAFS THROUGH 18Z SUNDAY/

Issued at 105 PM EST Sat Mar 7 2026

Latest observations show lingering IFR and MVFR conditions across Upper Michigan as of 18z Sat as a cold front tracks across the U.P., bringing snow to KCMX and a rain/snow mix to KSAW. Expect conditions to improve to VFR from west to east this afternoon as precipitation tapers off and skies clear behind the departing cold front. Winds will increase out of the southwest tonight ahead of another system passing well to the north across Ontario. This will introduce low level wind shear to the terminals overnight between roughly 06-12z Sun. Profiles become more unidirectional with height through Sun morning but surface winds remain gusty through the end of the TAF period, especially at KCMX where winds will gust as high as 35 kt. Expect predominantly dry weather with VFR conditions tonight into Sunday, though can't rule out a light rain/snow mix and a few brief bouts of MVFR (PROB30) at KIWD and KCMX tonight.

MARINE

Issued at 134 PM EST Sat Mar 7 2026

Northerly to northwesterly winds have been noted behind a swath of snow migrating eastward through the lake. These northwest winds will lighten through the afternoon and evening. Tonight through, another system moving through Ontario will result in southwest winds increasing to gales from west to east, which will linger into Sunday afternoon when they shift to westerlies and begin lightening. Reprieve isn't long and by Sunday evening, southerly winds increase again to 25 to 35 knots, with the strongest winds currently anticipated east of Keweenaw Point early Monday morning. Winds lighten through the day Monday, likely falling below 20kts lake-wide by evening.

Tuesday into Wednesday, another period of elevated winds is expected, with potential for gales by Tuesday night into Wednesday night. Additionally, a stronger system looks to move through the Upper Great Lakes late in the week, potentially resulting in high end gales and storms Thursday night and Friday.

MQT WATCHES/WARNINGS/ADVISORIES

Upper Michigan... None. Lake Superior... Gale Warning from 1 AM EST /midnight CST/ to 11 AM EST /10 AM CST/ Sunday for LSZ162.

Gale Warning from 1 AM to 5 PM EST Sunday for LSZ242>244-263- 264.

Gale Warning from 5 AM to 5 PM EST Sunday for LSZ245>251- 265>267.

Lake Michigan... None.