textproduct: Marquette

KEY MESSAGES

- A pair of week systems bring chances for showers tonight/early Sunday and again Monday/Monday night. Minimal impacts expected.

- Cooler than normal temperatures expected through much of next week and beyond.

DISCUSSION

Issued at 107 PM EDT Sat May 2 2026

Noon GOES-East Day Cloud Phase RGB imagery shows mostly clear skies over the UP region save for some fair weather, shallow cu fields over the interior west. RAP analysis shows a pair of substantial closed lows aloft, one over Ontario/Quebec and another just off the Oregon/Northern California coast, with ridging separating them over the Rockies. This results in expansive surface high pressure of around 1020-1025 mb centered over the southern Plains but extending into the Midwest. This pattern will hold for most of this forecast period as a shortwave currently over the Canadian Four Corners (MB/SK/NU/NT) will only serve to reinforce the eastern closed low while stubborn ridging surrounds the closed low on all sides (over the Gulf, over SW Canada, and in the northeast Atlantic) throughout the forecast period. Periodic ridge-riding shortwaves will provide some variation in the weather but impacts look to be minimal.

For today, fair weather will continue, though RHs look to be around 10% too high from the NBM initialization as temperatures are outpacing the NBM and observed Tds are a smidge lower than the NBM. Despite this, fire weather concerns will be low for the most part despite this as wind gusts should remain sub-20 mph for most of the area and highs will remain below 60.

Tonight, a minor clipper shortwave currently over the ND/MN/MB triple point will make its way to the region, bringing light rain showers passing from the northwest to southeast. By Sunday evening, the 12Z HREF 25th percentile gives a reliable floor around a tenth of an inch and the 75th percentile gives a reliable ceiling around a quarter inch. This should have minimal impact on the improving hydro situation with the bulk of the snowmelt complete and only a few Flood Advisories remaining. Low temperatures around the freezing mark will allow a few snowflakes to mix in early in the morning, but no accumulations are forecast. Showers depart the region Sunday afternoon to evening.

Further minor ripples in the 500mb flow and decreasing 500mb heights (due to the aforementioned reinforcing shortwave to the far north) will resume weak shower activity over the UP for Monday as a surface low pressure passes through northern Ontario. Expect similar totals and (lack of) impacts on Monday as for Sunday. 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 beyond. 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 /18Z TAFS THROUGH 18Z SUNDAY/

Issued at 219 PM EDT Sat May 2 2026

VFR will be the predominant flight category for the TAF period with high pressure over the region. However, that will break down early tomorrow morning (Sun 12-15Z) as a weak system brings rain chances from west to east and MVFR conditions with it, especially at CMX.

MARINE

Issued at 107 PM EDT Sat May 2 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. In fact, the one forecasted period of wind gusts exceeding 20 kt begins Sunday night 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 Sunday through early Monday then becoming westerly to northwesterly late Monday through mid Tuesday following the passage of a 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 15 percent.

MQT WATCHES/WARNINGS/ADVISORIES

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