textproduct: Marquette

KEY MESSAGES

- Daytime highs above freezing (especially today) will support gradual snowmelt across the UP, which will cause river levels to gradually rise.

- Monday night through Tuesday, a disturbance will bring thunderstorms to the southern UP, a few of which may be strong-to- severe. The SPC has issued a Marginal Risk for severe hail for the southern UP. For the northern UP, a mix of rain, freezing rain, and snow is expected, though accumulations will be mostly light.

DISCUSSION

Issued at 308 PM EDT Sun Mar 29 2026

Afternoon GOES-East Day Cloud Phase RGB imagery shows a couple of layers of fair weather clouds over the UP this afternoon, with the RAP analysis showing quasi-zonal flow across the region, though the flow is northwesterly and being upstream of a broad ridge, the negative vorticity associated with that is causing subsidence and the aforementioned fair weather today. Expect high temperatures to climb well above freezing across the entire UP today, with the MI/WI state line climbing to the 50s and even 20% likely to break into the 60s today, per the HREF. Soundings show copious amounts dry air in the bottom 10kft of the atmosphere. This has already caused some interior west surface RHs to fall to around 30%, though winds are light enough and enough snowpack is present that fire weather concerns are low. Still, this is a sign of the transition in the seasons and a good time to brush up on fire weather situational awareness.

This quiet spell continues tonight through Monday morning given the absence of any shortwaves and the aforementioned presence of significant dry air. While the snowpack for much of the UP will survive today's relative heat wave, given observed SWEs in much of the northern half of the UP in excess of 1 foot, the interior western and southern UP may start to see larger areas with no snowpack as those are the areas NOHRSC shows with the least SWE. Snowmelt is a long-range concern at this point given that some small rivers and streams are already approaching or exceeding bank full with plenty of water suspended in the snow that is yet to melt.

The coming week looks to be an active one. Monday through Tuesday, a 500mb trough will push just north of the US/Canada border from the Rockies to the Prairie. This will help organize a surface low of around 1000 mb over southern MN by 00Z Tuesday. This low looks to track across Lake Michigan, then the Lower Peninsula, then Lake Huron and into Canada throughout Tuesday, though for only being around 60 hours out, the ensemble spread in the location of the surface low is frustrating, with the Euro ensemble showing low centers from Cedar Rapids, IA to Lake Timiskaming (Ontario/Quebec line) at 18Z Tuesday. What this translates to at the surface are chances of freezing rain is around 20% throughout much of this system (total accumulations only 20% likely to exceed half a tenth of an inch), a slightly increased coverage of snow chances, and lingering thunderstorm chances for Menominee County and the Lake Michigan shores. While the coverage of area that may experience snow has expanded south somewhat, snow totals have not, with even the 90th percentile of the LREF showing an inch of snow accumulation.

Further south could be more interesting, with the surface low's southerly flow pushing moist flow into the area (NAEFS humidity, PWAT, and vapor transport plots all in excess of 90th climo percentile), with steepening lapse rates supporting Euro ensemble mean MUCAPE overnight Monday into Tuesday of 500-900 J/kg (which is a downward trend from 24 hours ago, but not by a ton). The wind profile is interesting as well, with the surface low passing just to the south providing 0-500mb bulk shear values in excess of 65 kt. To show how unusual the thunderstorm environment is, the Euro EFI for CAPE/Shear is in excess of 0.8, showing that most of the Euro ensemble is showing supportive parameters for strong thunderstorms relative to normal, as well as the Shift of Tails being between 0 and 1, meaning that at least some members of the Euro ensemble show parameters for severe weather that are high. Should the warm frontal forcing be sufficient to kick off some thunderstorms, some strong to severe storms overnight across the southern tier cannot be ruled out, with the SPC placing Menominee County in a Day 2 Marginal Risk (mainly for hail) and the Lake Michigan shores in a Day 3 Marginal Risk. As the low pushes through Tuesday, the cool northerlies will keep a complicated precipitation type forecast in play, though chances of freezing rain should be 15% or less, so primarily a question of rain vs snow for Tuesday. While a brief heavier shower is possible in a convective cell/around thunderstorms, rainfall totals should be manageable, with chances of 24-hour precip rates exceeding 1 inch are 10% or less.

850mb temperatures Tuesday night into Wednesday morning have trended a bit warmer, now only bottoming out at around -11C, which is much more borderline for post-system lake effect snow showers. The wind direction does continue to be likely (70+%) to be at least north of northwest, if not fully northerly to northeasterly. LES is not expected to overstay its welcome though, as high pressure well into the 1030s mb overspreads the northern Great Lakes basin by Wednesday night into Thursday. The synoptic setup is not done for the week yet - ensembles show a shortwave emerging into the Southern Plains Thursday morning that could (up to 30% chance) bring more precipitation to the region late Thursday. A much deeper trough pushing through the northern US Rockies Thursday evening could be attention-grabbing for the Friday-into-next-weekend period, which could set up another round of active weather similar to the early week system.

AVIATION /00Z TAFS THROUGH 00Z MONDAY/

Issued at 714 PM EDT Sun Mar 29 2026

VFR will prevail through the TAF period along with light winds. As the boundary layer decouples late this evening there will be a period of LLWS at SAW but that should only last a few hours as winds above the boundary layer weaken. Guidance has backed off on the prospect for fog at SAW tonight, have removed mention of MVFR vsby from the TAF.

MARINE

Issued at 308 PM EDT Sun Mar 29 2026

A lack of nearby systems keeps wind gusts below 20 knots today and tonight. Monday morning, in response to an approaching low pressure from the west to southwest, northeasterly winds increase to near 25 kt in the west half by the evening hours. Overnight, the 25-30 kt gusts spread to the remainder of the lake, though gale force gusts are 10% or less likely. Tuesday, winds becoming northerly will bring gusts below 20 kt for the west half, though winds over the east will remain above 20 kt until Wednesday morning. Waves will be 4-8 ft from Monday night to Wednesday, and the cool northerly flow will cause some moderate freezing spray over the east half of the lake Wednesday morning. Quiet weather over the lake is short lived as northeasterly flow increases to 25-30 kt by Thursday afternoon ahead of the next disturbance, with chances of gales 30-50% west of a line from Saxon Harbor to Grand Marais, MN Thursday night. Gale chances wane Friday, but gusts of 20-30 kt are expected to last into the weekend.

MQT WATCHES/WARNINGS/ADVISORIES

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