textproduct: Marquette

KEY MESSAGES

- A pair of systems bring chances for showers this afternoon and Monday. There is a slight chance (20-40%) for thunderstorms east of US-41 this afternoon. Otherwise, minimal impacts expected through Monday.

- Benign weather with cooler than normal temperatures expected through much of next week and beyond.

DISCUSSION

Issued at 146 PM EDT Sun May 3 2026

Noon GOES-East Day Cloud Phase RGB imagery shows mostly fair weather skies (either clearing or shallow cu) over the UP, save for a line of shallow convection draped across Alger and Schoolcraft counties, with MRMS precip estimates of around a tenth of an inch of rain associated with the line. RAP analysis shows a pair of substantial closed lows aloft, one over Hudson Bay and another just off the California coast, with ridging separating them over the southern Rockies as well as a ridge stacked to the north of the Cali Coast low. The stacked nature of the features upstream plus the large size/small quantity of waves over much of North America will lead to a mostly blocked and stagnant pattern, and the sensible weather pattern will be driven by ridge-riding shortwaves bringing periodic weak precipitation and cooler than normal temperatures from the persistent northerly to northwesterly flow aloft.

For today, one such shortwave will continue sending a cold front across the UP, and that front plus diurnal heating will create conditions for some thunderstorm activity in the east today. CAPE will be sufficient for thunder, though not high enough to suggest enough buoyancy for severe weather, with HREF mean CAPE values of 250-500 J/kg in the east half. The front will help drive sufficient shear to organize thunderstorms, with HREF 0-3km SRH of 100-150 and 0-6km shear values around 35 kt. This combines to make an environment that the HREF suggests is around 20-40% likely to generate thunderstorms east of US-41 from 3 PM to 6 PM Eastern.

Further minor ripples in the 500mb flow and decreasing 500mb heights will resume weak shower activity over the UP for Monday as a surface low pressure passes through northern Ontario. Expect similar rain totals and (lack of) impacts on Monday as for today. It will be a gustier day, with NBM wind gusts up to 25-30 kt by midday Monday.

Once shower chances end Monday night, a period of dry weather ensues, with only minor diurnal rain chances (up to 30%) Thursday and Sunday. Fire weather will be the focus of the weather impacts during the midweek period as NBM RHs fall to around the 30 percent mark during the afternoon hours of Tuesday and beyond, and NBM wind gusts are around 15 kt (or 15-20 mph) during those times. Sustained cool northerly flow will keep temperatures below normal, with highs generally in the mid-50s or below and lows in the 20s for the interior and around freezing at the shores of the Great Lakes.

AVIATION /00Z TAFS THROUGH 00Z TUESDAY/

Issued at 732 PM EDT Sun May 3 2026

VFR conditions will prevail through the TAF period. A lake breeze was bringing light northeast winds to SAW early this evening while most of the U.P. was under west-nortwest winds gusting 20-25kt. Expect winds to become southwesterly around 10kts at sunset as mixing ends. Overnight a cold front will approach the area with a 50kt low level jet developing. This will bring a period of LLWS to the TAF sites late tonight into Monday morning. Scattered light showers will accompany the front as it sweeps across the U.P. from west to east Monday morning. Didn't add a mention of showers at this time, any impacts to vsby or cigs will be minimal as the low levels will remain fairly dry. Expect westerly winds behind the front gusting 25-30kt.

MARINE

Issued at 146 PM EDT Sun May 3 2026

A stagnant weather pattern defined by stubborn troughing over the James Bay region and stubborn ridging near the East and West Coast will lead to few chances for gusty winds and high waves. The only forecasted period of wind gusts exceeding 20 kt begins tonight and lasts through Tuesday afternoon in response to a surface low cutting through northern Ontario. This will initially lead to southwesterly winds gusting to near 25 kt late today through early Monday then becoming westerly to northwesterly late Monday through mid Tuesday following the passage of another cold front. Waves look to build to 4-6 ft Monday morning through Tuesday evening as a result. Chances of gales with this system are around 30 percent, though only in the nearshore waters in the southerly to southwesterly flow regime.

MQT WATCHES/WARNINGS/ADVISORIES

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