textproduct: Marquette

KEY MESSAGES

- Scattered showers and thunderstorms develop Tuesday afternoon and evening.

- Showers and thunderstorms become more widespread Wednesday morning through Thursday morning.

- Temperatures will remain above climate normal in the early week, and closer to normal mid-week.

DISCUSSION

Issued at 346 PM EDT Mon Jul 6 2026

This afternoon, high pressure resides over the region on the lee side of a sprawling ridge spanning Quebec to Minnesota. Light surface winds and minimal cloud cover are allowing temperatures to warm steadily. Currently, temperatures inland reach into the low 80s with a few spots hitting 85; the Keweenaw and areas along the Lake Superior shoreline are lower, in the 60s and 70s. Overall, with highs just above climate normal (0-5F above near shorelines and 5- 10F above inland) and dewpoints in the mid 50s, this early July day is realizing comfortable conditions.

Tomorrow brings increasing chances of precipitation as the ridge decays eastward and a robust low propagates toward Hudson Bay. Accompanying this system, multiple subtle boundaries could lead to scattered thunderstorms in the west and south-central portions of the CWA in the afternoon and evening. A weak boundary associated with a trailing trough from the Hudson Bay low moves west to east throughout the day. From this boundary alone, CAMs agree that some small totals (<0.15") will reach the ground in the west and central areas. However, given conducive lake breeze conditions - the HRRR shows a Lake Superior breeze penetrating fairly deep inland by afternoon - anomalously high moisture will have multiple opportunities to initiate. HREF shows modest mean CAPE values between 1000-1500 J/kg in afternoon and evening, and soundings show elevated CAPE for locations in the west and south for this same time frame. With PWAT values between 1" and 1.5" per the EPS, some spots could experience isolated stronger thunderstorms and locally higher rain accumulations. However, given only 20-30 knots of bulk shear per the REFS, potential for severe storms remains low; SPC has the CWA in the General Thunderstorms category.

Periods of rain are expected throughout Wednesday and into early Thursday. As the amplified ridge over Quebec breaks down today and tomorrow and the Hudson Bay low progresses east, gradient flow over CWA becomes strongly zonal. This sends anomalously high PWATs between 1.75" and 2" over the region by early Wednesday morning. At the same time, an upper level jet streak moves over region with a trailing lobe lingering over the area Weds evening, leaving the CWA situated in the jet streak's rear-right entrance region. With synoptic lift present and a moist atmosphere, rain is expected to move west to east beginning early Wednesday morning and continuing through Thursday morning. A moist atmosphere combined with a slow- moving theta-E boundary increases potential for heavy rain; in WPC's Day 2 Excessive Rain Outlook, the CWA is currently outlooked in the Slight (15%) category. NBM plan view 24h probabilities of exceeding 2" exist up to 20%, and the 90th percentile of 6-hour accumulations is over 1" in some locations. Thus, locally higher amounts of heavy rainfall may occur, most likely in the west and south. The northern 2/3 of the CWA is outlooked in SPC's General Thunderstorms category, and the southern 1/3 in Marginal, so potential severe storms on Wednesday is low.

The area dries out by midday Thursday as high pressure moves back in behind the Hudson Bay low, and temperatures should be relatively close to climate normal. Friday marks the beginning of a large ridge building over the Great Plains and extending from the Sierra Mtns to the Appalachians. Anticyclonic mid-level flow sends warm and dry desert air circling toward the Upper Midwest, resulting in very warm temperatures by Sunday.

AVIATION /18Z TAFS THROUGH 18Z TUESDAY/

Issued at 145 PM EDT Mon Jul 6 2026

High pressure will continue to bring light winds and VFR conditions to Upper Michigan terminals through tonight. An approaching system will bring increasing high clouds late tonight into Tue morning. Shower and thunderstorm chances will increase by Tue afternoon, introducing PROB30 for -SHRA to KIWD near the end of the period. Any precipitation looks to remain south of KCMX and hold off at KSAW until after 18z Tue.

MARINE

Issued at 346 PM EDT Mon Jul 6 2026

Light winds prevail tonight into tomorrow. Eastern portions of Lake Superior may see higher southerly winds with gusts to 20 knots for a few hours early Tuesday morning as flow organizes ahead of a weak frontal boundary. This precedes periods of rain and thunderstorms Tuesday afternoon through Thursday morning; winds may be higher near outflow boundaries, though severe storms are not expected. As high pressure builds back in on Thursday, winds lay down through Saturday afternoon.

MQT WATCHES/WARNINGS/ADVISORIES

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