textproduct: Marquette

KEY MESSAGES

- Temperatures will trend above normal for Monday and Tuesday with highs mainly in the 80s.

- Scattered showers and thunderstorms develop Tuesday afternoon and evening.

- Showers and thunderstorms become more widespread Tuesday night into Wednesday.

DISCUSSION

Issued at 106 PM EDT Sun Jul 5 2026

Early afternoon water vapor imagery and RAP analysis reveals weak troughing over the eastern UP/lower MI slowly moving east, while drier air associated with ridging is advancing toward the western UP. At the surface, a ridge of high pressure extends southwest over Lake Superior/UP from a center over Hudson Bay. Expect the ridge to further assert itself through tonight over the local area as the trough exits east. With a drier airmass, good radiational cooling is expected tonight, with lows away from the immediate shorelines falling into the upper 40s and low 50s. For Monday, the high continues to shift east, resulting in weak return flow, with highs mainly in the low to mid-80s.

Next period of potentially impactful weather looks to be in the Tuesday afternoon through Wednesday timeframe. This will occur as mid/upper level zonal flow strengthens modestly across the northern tier of the CONUS, and a weak low-level boundary becomes strung out from central Ontario through Lake Superior and the UP, southwestward into the northern Plains. Meanwhile, modest SW flow in the 925-850 mb layer will help to boost PWATs up to 1.5-1.75 inches, or +1 to +2 sigma per the NAEFS. Expect scattered showers and storms to develop Tuesday afternoon and evening along the low-level front, with best coverage over the west half. Modest midlevel lapse rates should keep SBCAPE around 1000 J/kg or less with deep-layer shear around 25 kt or less, which should limit the severe weather threat overall. However, the potential for multiple rounds of convection along the stalled boundary, along with relatively slow storm motions, will result in a heavy rain threat with the most widespread coverage of showers and storms by Wednesday. Modest instability values are a limiting factor, however. Latest NBM probs of exceeding 2" of rain in 48 hours are 20-30% in the west and central UP.

Dry and seasonable weather is favored to end out the week Thu/Fri in the wake of Wednesday's system as high pressure builds in again from the north.

AVIATION /18Z TAFS THROUGH 18Z MONDAY/

Issued at 128 PM EDT Sun Jul 5 2026

High pressure promotes VFR conditions under mostly clear skies through the period at Upper Michigan terminals. KCMX and KSAW will continue to see winds in the 8-10 kt range through the afternoon, which could be of operational significance to smaller aircraft. Winds become light this evening after 00z.

MARINE

Issued at 106 PM EDT Sun Jul 5 2026

High pressure will result in light winds through Monday night. The high shifts east for Tuesday as warmer and more moist air arrives. This is likely to result in periods of rain and thunderstorms from late Tuesday into Wednesday night. Areas of fog will be possible during this time as well, especially where it rains. Winds remain less than 20 kt throughout the week.

MQT WATCHES/WARNINGS/ADVISORIES

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