textproduct: Marquette

KEY MESSAGES

- Ongoing showers and isolated thunderstorms in the central UP are expected to drop off shortly after 00Z.

- Monday is expected to be dry and cool, and temperatures should remain below normal this week.

- Tuesday night through Thursday morning bring potentially widespread rain showers and thunderstorms.

DISCUSSION

Issued at 349 PM EDT Sun Jun 21 2026

The summer solstice occurred this morning at 4:24 EDT, marking the moment of maximum axial tilt toward the sun for the northern hemisphere. The far eastern reach of our CWA (Luce County) experienced solar noon at 13:43 local time (EDT) and the far western reach (Ironwood) saw solar noon at 13:03 local time (CDT). The UP will experience approximately 15 hours and 50 minutes of daylight today, with the northernmost portions of the CWA (the Keweenaw) having about 20 minutes more daylight than the southernmost portions (Menominee County).

On this day of maximum potential insolation, cool temperatures and lake breeze-enhanced showers rule the day. Current satellite imagery shows cyclonic flow around a depression in southern Ontario north of Isle Royale. Per the GEFS, this weak low is associated with anomalously cold 850mb temperatures, contributing to below normal temperatures once again. Observations show a lake-enhanced convergence boundary along an east-west axis across the UP, which is lining up with mid- and upper-level synoptic support. Base reflectivity shows scattered showers sprawled along this axis with no lightning strikes. Diurnal instability contributes to some lift; SPC Mesoanalysis analysis places MUCAPE between 250 and 500 J/kg for most of the UP. Nevertheless, PWATs remain anomalously low, and HREF 6-hour QPF distributions once again showing between 0" and 0.5" inches of accumulation. Be prepared to experience a burst of rain should a cell track above you. Given the moderate influences, though, no severe storms are expected, and what storms do exist are anticipated to drop off shortly after 00Z.

With a series of low mid-level heights feeding toward our CWA from western Canada, expect cooler pattern to continue through week. As today's low moving east, weak surface high pressure settles into place through Tuesday. 850 mb heights remain anomalously low and winds maintain some northerly component, so expect highs in the high 60s and low 70s, and lows down to 40 inland and high 40s along the shorelines for Monday. Tuesday will be slightly warmer.

A low tracking from Manitoba on Tuesday brings in the next significant precipitation chances. Ensembles show a ~1014mb surface low dropping southeast from Minnesota late Tuesday, deepening to ~1012mb and reaching Green Bay by late Wednesday. The GEFS shows moisture reaching up the Gulf and resulting PWATs between 1" and 1.25" coinciding with system, and the RRFS indicates MUCAPE in the western UP up to 1000 J/kg. With more moisture available and decent instability potential, we may see more widespread rain showers along with non-negligible chances for thunder.

AVIATION /18Z TAFS THROUGH 18Z MONDAY/

Issued at 139 PM EDT Sun Jun 21 2026

Generally VFR conditions with light and variable winds expected across the area this afternoon and evening. Showers are expected to develop along the Lake Superior lake breeze this afternoon, with a 40% chance of a shower affecting KSAW. A TEMPO group has been added to the SAW TAF for this afternoon to account for the temporary reduction to MVFR as any showers move over the terminal. Late tonight, there is a 50% chance of fog developing at SAW and IWD after 08Z. Any fog that does develop will quickly abate after sunrise, with VFR conditions expected for the remainder of the TAF period.

MARINE

Issued at 349 PM EDT Sun Jun 21 2026

Light, generally northerly flow with winds and gusts <10kt prevail on Lake Superior and Bay of Green Bay through Tuesday. Monday afternoon and night, the eastern part of Lake Superior may experience NW'ly gusts to 15 kt.

A low tracks through the Upper Great Lakes on Wednesday, bringing with it widespread chances of showers and thunderstorms. Winds shift direction Tuesday evening through Thursday morning, depending on the track of the system. Sustained winds are light and wind gusts are are not expected to exceed 20 kts during this time. Significant wave heights should remain <2ft on Lake Superior and <1ft on the Bay of Green Bay.

MQT WATCHES/WARNINGS/ADVISORIES

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