textproduct: Marquette

KEY MESSAGES

- There is a Potential (20-40% chance)for showers and storms this afternoon through Wednesday afternoon. Severe storms are not expected.

- Temperatures are expected to be seasonably warm to slightly above average through Wednesday, before cooling to slightly below average through the weekend.

- Dry weather Thursday and Friday ahead of the next chances for more widespread rain this weekend (around 60% chance).

DISCUSSION

Issued at 130 PM EDT Tue Aug 11 2026

Broad northwesterly flow aloft continues this afternoon thanks to the positioning of a closed low over Hudson Bay and large scale ridging over south-central CONUS. Small scale fluctuations in the generally northwestern flow could provide the impetus for scattered showers and potentially a thunderstorm or two this afternoon and evening. Agreement among the CAMs has improved somewhat on timing and extent of showers for this afternoon.HREF SBCAPE forecasts for this afternoon keep max values at or below 1500 J/kg, while the ensemble means remain around 500 J/kg and the ensemble minimum keeps SBCAPE at 0 J/kg across the CWA. Shear remains weak and unidirectional. Thus, while SBCAPE may be sufficient to support a couple of strong thunderstorms this afternoon, severe thunderstorms are not expected. HREF chances for showers producing at least a tenth of an inch of rain within 25 km of any point range from 20-40% this afternoon and evening.The upper level pattern remains largely the same throughout Wednesday afternoon, indicating that the potential for scattered showers and thunderstorms remains in the forecast for tomorrow.

A broad 500mb ridging pattern is expected to move over eastern CONUS Wednesday night into Thursday morning,indicating increasing surface pressure and dry conditions Thursday and Friday. During the same period, a trough currently located over Seattle and Vancouver is likely to progress eastward over Canada and northern CONUS. Uncertainty remains regarding the precise timing, track, and depth of the trough, and thus its impacts for weekend conditions. At this time, the highest chances (up to around 60%) for precipitation are expected to occur between Saturday morning and Sunday morning, although given the uncertainty with trough timing and depth, the location, timing, and amount of precipitation is subject to change. Generally northwesterly flow at the 500 mb is likely to resume Sunday night through Tuesday as ridging returns to central CONUS, continuing the pattern of weak precipitation patterns over the UP.

AVIATION /18Z TAFS THROUGH 18Z WEDNESDAY/

Issued at 130 PM EDT Tue Aug 11 2026

VFR conditions prevail this afternoon with mostly clear skies and light winds seen across the UP. A few scattered diurnal showers may be seen at SAW this evening, but confidence is low given ample dry air at the surface and weak forcing for ascent. Have included a Prob30 for showers at SAW from 21-03z. Otherwise, patchy fog may be seen overnight, mainly across the central UP but again dry air at the surface and low ensemble agreement owes to low confidence in fog below MVFR at any site.

MARINE

Issued at 130 PM EDT Tue Aug 11 2026

Mostly calm weather with winds 15 kts or less will be seen over the area the next few days, save for potentially some showers and thunderstorms over northern Green Bay and Lake Michigan this evening and again Wednesday evening (no severe weather expected). However, as high pressure begins to move out of the Upper Great Lakes on Friday, we may see some northeasterly winds of 20 to 25 knots over the far western lake near the Apostles and Duluth by Friday afternoon as low pressure approaches from the west. While winds weaken by Friday night, they restrengthen once again by Saturday as a shortwave low brings what appears to be an occluding front over the Upper Great Lakes. Thus, expect southeast to southerly winds up to 20 kts over northern Green Bay and northern Lake MI by Saturday afternoon, with central Lake Superior potentially seeing southeast to southerly gusts of 20 to 30 kts, in addition to the showers and storms moving across the area. Behind the front into Sunday, expect the winds to weaken, although they may increase up to 20 to 25 knots from the northwest over Lake Superior again by Sunday afternoon.

MQT WATCHES/WARNINGS/ADVISORIES

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