textproduct: Marquette

KEY MESSAGES

- There is a chance for rain showers tonight over the southern half of the U.P. Lake effect rain showers will become widespread Wednesday afternoon and transition to snow Wednesday night.

- An extended period of lake effect snow is expected for Wednesday night into Saturday morning. The most impactful periods look to be during the overnight hours, especially Thursday night. 3-6" of snowfall is expected for the Wednesday Night through Friday period over the higher terrain of Marquette and Alger Counties with 1-3" elsewhere (expect less close to Lake Superior, Menominee County and the Eastern U.P.).

- Temperatures rebound to unseasonably warm 50s early next week.

DISCUSSION

Issued at 315 AM EST Tue Nov 10 2026

Early this morning GOES water vapor imagery and GFS 500mb model height analysis showed an upper level low pressure over Newfoundland and Labrador with west-northwest flow over the Great Lakes region. Shortwaves could be seen embedded in the flow with one passing north of Lake Superior. IR imagery showed passing high clouds over the southern U.P. but otherwise is was clear over the north and east. Despite the clear skies temperatures had stayed warmer in the wake of a cold front due winds/mixing as isalobaric flow with pressure rises in the 2 to 3 mb per 6 hour range kept a breeze for most areas. Surface observations showed winds were gusting 25-30 mph over the Keweenaw and near Lake Superior. This was keeping temperatures in the 40s to low 50s with the exception of a few pockets of 30s over the interior, where the boundary layer had managed to decouple.

Another warm day for November is on tap for the U.P. with highs reaching the mid 40s north and mid 50s far south. This puts highs about 5-10 degrees above seasonal averages. This will be the last well above average day for a bit as cooler weather comes in for the later half of the week and into the weekend.

Tonight low pressure will track south of the area bringing increasing cloudiness to the area. An area of rain will accompany this low on the north side in an area of moderate fgen providing forcing coinciding with deeper moisture. Models diverge on the exact placement of this feature but felt confident enough to bring PoPs up over the southern half of the U.P. late tonight into Wednesday morning. NBM was running cold for tonight with temperatures below freezing over the interior. Given the increasing cloud cover and rain chances opted to blend in some raw (non-bias corrected) guidance.

Wednesday through Friday multiple shortwaves will drop south out of Canada as the upper low over Newfoundland shifts west, reaching Lake Huron by Friday. This will bring a sustained period of cold air advection to the area with 850mb temps falling into the -8 to -10C range, starting Wednesday afternoon. Thus expect temperatures to start out in the 40s for the first half of the day but we should see falling temperatures over the northern U.P. during the afternoon as a cold front pushes south and northerly flow develops. Widespread lake effect rain showers are expected to develop on Wednesday afternoon over the northern part of the U.P. as well. As temperatures cool through the evening expect snow to mix in over the higher terrain with a changeover to snow elsewhere as the night progresses. With continued caa and additional embedded shortwaves expect period of LES through Saturday morning with daytime temperatures (highs in the 30s) falling to near or slightly below average.

Several forecast challenges present themselves with this event and did quite a bit of deviation from the NBM (blended guidance) in the forecast package. NBM is struggling to handle the pattern change with daytime temperatures too warm and overnight lows too cold (trained on cool, clear nights). Warmed temperatures up quite a bit for Wednesday and Thursday night. NBM was indicating lows in the low to mid 20s over the interior with subfreezing temperatures to the Lake Superior shoreline. This seems unlikely given 850mb temps are only -8 to -10 and the lake temperatures are 8-10C. Additionally, widespread cloudiness and precipitation will limit cooling. Brought low up to around 34 near the lakeshore and low 30s over the eastern U.P., with upper 20s across the west for Wednesday night. Similar adjustments were made for Thursday night but might still be too cool given continued onshore flow and previously mentioned factors. As far as intensity and accumulations the NBM continues to struggle with QPF; blended in other guidance (REFS, Canadian) to bring up QPF amounts. Convergent flow favors at least a few more dominant bands setting up over the eastern half of Lake Superior with another band over the central part downwind of Lake Nipigon which should help prime the atmosphere (for moisture) and provide convergent flow in the low levels. Models have come into better agreement with the depth of moisture with most indicating at least some of the DGZ is intersected along with inversion heights up to 8kft (possibly higher over the relatively warm waters of Lake Superior). Thus moderate snowfall rates seem likely in the more dominant bands with the potential for brief heavy snow bursts over the higher terrain of the north-central and possibly Keweenaw. Marginally cold low levels and warm ground temperatures will probably keep snow ratios on the lower side but still expecting several inches of snowfall over the higher terrain (Keweenaw, Marquette County and Baraga County) Wednesday night through Friday, with the most impactful period being during the overnight hours with some improvement during the daytime as temperatures warm close to or slightly above freezing. Near the lakeshore and over the eastern U.P. temperatures will likely remain above freezing but wouldn't be surprised to see accumulations in the grassy areas at times with enough wet-bulb effects in the more intense bands. Overall this looks to be a traditional sub-advisory event but worthy of enhanced messaging given it will be the first more widespread event of the season. Thus wouldn't completely rule out headlines for the event but at this point will message through other channels. As typical with LES the guidance is also spread on the location of the more dominant bands but an overall forecast of 3- 6" over 48 hours seems reasonable for the aforementioned high terrain areas with 1-3" elsewhere, away from the shoreline. Bands may manage to travel well inland, to the MI/WI border as theta-e lapse rates look to become conditionally unstable over much of the area, even during the overnight hours Wednesday night into Friday morning.

LES should wind down Saturday, confined mainly to northern Marquette County and Alger County during the morning hours with a few lingering rain/snow showers into the afternoon. Temperatures begin to rebound on Sunday, warming into the 40s and eventually back into the upper 40s to 50s for early next week.

AVIATION /18Z TAFS THROUGH 18Z WEDNESDAY/

Issued at 1251 PM EST Tue Nov 10 2026

VFR conditions hold at all three sites for most of this 18Z TAF period before deteriorating to at least MVFR CIGs & VIS after ~12Z tomorrow. Breezy conditions die down this evening for light and variable winds as cloud cover increases overnight. All sites see VCSH during the first part of the day tomrrow followed by -SHRA/BR as precipitation becomes more widespread. Guidance for both CIGs and VIS indicate IFR conditions are possible (20-30%) during the last 4 hours of this TAF period. However, this was omitted for current issuance due to decreasing LAMP probabilities from recent model runs and short-lived duration of IFR conditions. Northerlies increase after ~14Z tomorrow, preceding a transition from rain to lake effect snow as temperatures drop overnight Wednesday night.

MARINE

Issued at 315 AM EST Tue Nov 10 2026

Lake Superior: West-northwest winds of 20-30 kts this morning will subside through the day, falling below 20 kts by this evening. Winds shift north Wednesday night behind a cold front and increase to 20- 30 kts, highest over the eastern half of the lake. Lake effect rain and snow showers can be expected resulting in visibility reduction below a mile in the heavier bands. Winds and lake effect will diminish Friday night with winds falling below 20 kts by Saturday morning, remaining northerly through the weekend.

Northern Lake Michigan and northern Bay of Green Bay: West-northwest winds less than 20 kts can be expected through Wednesday. Winds shift northerly on Wednesday night behind a cold front and increase to 20-30 kts. Winds then fall below 20 kts Friday night and remain northerly through the weekend.

MQT WATCHES/WARNINGS/ADVISORIES

Upper Michigan... None. Lake Superior... None. Lake Michigan... None.