textproduct: Marquette

KEY MESSAGES

- Benign weather and cooler than normal temperatures continue until the end of this week. Some diurnal rain and snow showers are possible during the daytime hours.

- Widespread rain showers return by Saturday. Some spots may get up to a tenth to a quarter of an inch of liquid.

- More cooler and dry weather is expected for early next week as high pressure descends over us from the Canadian Prairies.

DISCUSSION

Issued at 231 PM EDT Thu May 7 2026

A very similar weather pattern to the past few days continues to present itself today as GOES-East Day Cloud Phase imagery shows mostly low cumulus with a few streaks of deeper clouds where light showers are ongoing, with both rain and snow ptypes observed. RAP analysis shows a nebulous weather pattern over the Upper Great Lakes as surface high pressure is over Texas and low pressures are over Labrador and Saskatchewan. Aloft, RAP analysis shows the continued pattern of a 500mb deep trough over Hudson Bay with embedded shortwaves pivoting around the base of the trough. Meanwhile, ridging is over the West Coast and just off the East Coast while a closed low is over the northern Gulf of California. While there are some indications that this heavily blocked and low wavenumber pattern will progress some by mid next week, uncertainty is high. In the meantime, the weather pattern is dominated by cooler than normal temperatures and periodic light showers as minor wavelengths continue to wobble about the base of the longwave trough. For the rest of today, the HREF shows diurnal heating and the nearest upstream shortwave digging to allow for a reinvigoration of rain showers over the southern half of the eastern third this evening. HREF probs of a tenth of an inch of rain along an axis from from Manistique to Newberry by 00Z tonight are 50-70%. Ultimately, no impacts are expected from this as no thunder is forecast. Chances of precip fall below 15% in the wake of the minor shortwave around 05Z, with overnight lows tonight sub-freezing in the interior and around the freezing mark at the shorelines of the Great Lakes.

The weather pattern continues uninterrupted for the end of the work week as yet another day of weakly forced off and on again showers continues, with CAMs showing showers but spread out on the coverage and location of showers. A slightly warmer background westerly to southwesterly flow upstream as well as mostly clear to partly cloudy skies early will help bring slightly warmer temperatures to the UP with highs up to the mid 50s for most (though the normal high is around 60, so still a tough below normal). If clear skies can persist most of the day, enough diurnal heating and efficient mixing can occur to bring wind gusts near 20 kt and drop RHs into the 20s to teens percent, which would be cause for elevated fire weather concern despite the temperatures technically being too cool, but with the potential for showers during that time, the "elevated fire weather" solution is only a worst-case consideration for now, with a more likely solution being a repeat of conditions from the past several days.

Saturday, a cluster of ensemble solutions shows a surface low forming over Lake Superior in response to another of these such shortwaves pivoting around the main trough. It is not a given that it will occur, but if it does, widespread rain showers (maybe some snow showers in cool spots) will occur. Current PoP forecast for this package is around 30-50%.

By Sunday, the LREF shows some actual progress in the 500mb pattern, with ridging moving into the lee of the Rockies with the trough pushing into Quebec. This will push a surface high over the Great Lakes, though the NBM still carries some 15-30% PoPs on Sunday in case one final shortwave pushes through. Despite calming conditions, the flow aloft remains mostly northerly, so NBM highs Sunday are still 50 +/- 5.

With the continued progression of the pattern aloft, the beginning of next week sees a lot of spread in the global deterministic and ensemble solutions. With the approaching longwave troughing, a gradual increasing trend is observed in the NBM highs next week, with some 70s in the west half by Thursday. The earliest arrival time of the next system looks to be around 12Z Tuesday, though there are GEFS ensemble low centers in the area all the way into Wednesday afternoon, indicating that ensembles don't have a great handle on the window of precipitation by the midweek period.

AVIATION /18Z TAFS THROUGH 18Z FRIDAY/

Issued at 210 PM EDT Thu May 7 2026

VFR conditions persist across the terminals for the remainder of today, tonight, and into tomorrow as light rain and snow showers continue. This precipitation is courtesy of a weak impulse shortwave orbiting around its parent Hudson Bay low. Low (<30%) probabilities exist of showers near KSAW this evening (00Z-03Z), but only for a few hours and without change to flight category. Broadly speaking, light WNW'ly winds across the UP today give way to very light SW'ly flow tonight. KCMX should expect continued gusts up to 25kt throughout daylight hours today. There is a low chance (<20%) chance of fog at KSAW tonight, but no mention is made in the TAF.

MARINE

Issued at 231 PM EDT Thu May 7 2026

With major pressure systems staying away from the Upper Great Lakes for the rest of the work week, winds will stay below 20 kt until at least Saturday afternoon. To begin the weekend, there is a ~50% chance of a low pressure forming over the lake that can drive wind gusts near 20-25 kt especially in the east half of the lake. Winds fall below 20 kt Sunday morning, with a brief 30-50% chance of 20-25 kt gusts Sunday evening in the east. Winds remain sub-20 kt for the remainder of the period.

MQT WATCHES/WARNINGS/ADVISORIES

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