textproduct: Marquette

KEY MESSAGES

- A Clipper system brings widespread rain showers and a few rumbles of thunder through this evening, with light rain showers lingering into Wednesday morning.

- Warmer than normal temperatures are favored by the end of this week. In addition, a more active pattern is expected as we head towards the latter half of May.

DISCUSSION

Issued at 344 PM EDT Tue May 12 2026

Afternoon GOES water vapor imagery depicts a well defined low pressure system moving over Lake Superior from northwest Ontario, with a mid level dry slot moving over the central and eastern Upper Michigan as this morning's band of rain departs to the east. This is producing partially clearing skies in these areas as noted on visible satellite. Meanwhile, RAP analysis places an attendant 1004 mb sfc low near KIWD as of mid afternoon, with cloud cover and rain showers beginning to fill back in across the western U.P. in association with this feature. This will bring another round of scattered to widespread showers to the area this evening as the surface low tracks across the U.P. from west to east and reaches northern Lake Ontario by early Wednesday morning. Could see a few embedded thunderstorms within this activity through this evening, but am not currently overly bullish on this potential as current SPC mesoanalysis only depicts 100-200 J/kg MUCAPE across the area. Still, a few more hours of surface heating coupled with steepening mid level lapse rates as cold air advection moves in aloft on the back side of the system could generate somewhat more favorable instability, particularly across central portions of the U.P. where the most clearing has occurred. SPC maintains a marginal risk for severe thunderstorms across the southern half of Menominee County through this evening, but largely do not expect any strong thunderstorms across most of the area given meager instability and wind shear. In terms of rainfall, generally expect around a tenth of an inch or less of additional precipitation in most locations through tonight.

A few showers will linger into Wednesday morning, especially across the eastern half as cold northerly flow develops on the backside of the low. Could see a few snowflakes mix in over the higher terrain of Baraga and Marquette Counties towards daybreak Wednesday as temperatures dip near or just below freezing, but do not expect any accumulation. Expect drier and sunnier conditions to develop by Wednesday afternoon as surface high pressure builds in from the west, but high temperatures will remain largely in the 50s for one more day as the region remains under the influence of cold air aloft on the back side of the departing trough.

Warmer weather arrives on Thursday as upper level ridging moves overhead, producing highs mainly in the 60s across the eastern half and the low 70s in the west. Expect fairly dry conditions characterized by minimum humidity values in the 30s and into the 20s in the interior west, but relatively light winds will help to preclude any significant fire weather concerns. A front will bring another round of rain showers Thursday night into Friday as a low passes well to the north across Ontario. Do not expect a wetting rain out of this system at this time. The weekend has trended a bit drier as the area settles into quasi-zonal flow aloft, with temperatures remaining near or slightly above normal with highs generally in the 60s in the east and 70s in the west through Sunday. More active and wetter weather look to return by early next week as a shortwave trough ejects out of the COlorado Rockies with a broad low pressure system lifting northeast out of the Plains.

AVIATION /18Z TAFS THROUGH 18Z WEDNESDAY/

Issued at 157 PM EDT Tue May 12 2026

Despite a bit of a lull in shower activity at the moment, MVFR cigs are prevailing at SAW. And, IWD and CMX will also deteriorate to MVFR later today as low level moisture increases in association with a low pressure system. This evening, another round of showers, and possibly a thunderstorm, will develop. Conditions will fall to IFR and possibly LIFR at times as showers move over the terminals. Showers will become light late tonight but IFR cigs will remain through the end of the TAF period.

MARINE

Issued at 344 PM EDT Tue May 12 2026

Southerly gale force gusts will wind down across central portions of Lake Superior this evening as the clipper system continues to track eastward across Upper Michigan. This will bring a shift to northwest winds in the wake of the low tonight into Wednesday. Cold advection will result in gusty winds of 25-30 kt in many locations, but opted to cancel the Gale Watch for Wednesday as probabilities for gale force gusts have dropped to around 25% per both HREF and NBM guidance. Expect benign conditions with winds mainly 15 kt or less from as high pressure moves overhead Wednesday night into Thursday. The next system will bring another round of stringer southerlies to the eastern half of the lake Thursday night into Friday, but gale probabilities are relatively low (25-35%) at this time. Then expect mostly benign conditions to prevail through the weekend ahead of potentially more active weather early next week.

MQT WATCHES/WARNINGS/ADVISORIES

Upper Michigan... None. Lake Superior... Gale Warning until 6 PM EDT this evening for LSZ244-245-248- 249-264>266.

Lake Michigan... None.