Marine Weather and Tide Forecast for Copper Harbor, MI

DISCUSSION
Issued at 153 AM EDT Sat Jul 25 2026

Water vapor imagery and radar returns show showers and thunderstorms over northern Minnesota progressively making their way towards the U.P. early this morning as a dying cold front pushes eastward. With the LLJ losing steam (as well as the forcing along the front) and the front moving through during mainly the morning to early afternoon hours across the U.P., no severe weather is really expected. That being said, there may be a stronger cell or two that gets squeaked out as bulk shear is still around 30 to 35 kts along the front. The better, albeit much more conditional, chances for severe weather come behind the front this afternoon as clearing skies allow CAPE in the atmosphere to recover while 0-6 km bulk shear values range from 30 to potentially even 50 kts. However, with there really being no synoptic forcing mechanism to 'punch' convection up, showers and storms will have to rely on mesoscale processes (like the lake breeze) to get anything going. Thus, SPC keeps a Marginal (5%) Risk for severe weather over us for hail and wind today into early this evening.

Most guidance is now suggesting that convection will once again move into the area sometime on Sunday (save for the NAM). While a shortwave impulse is most likely moving into the region on Sunday, given that it's pretty weak, the convective potential will have to be made-up by the amount of CAPE in the atmosphere. Given that conditions will be very warm and somewhat muggy (high potentially in the lower 90s with dewpoints potentially around 70), by the afternoon hours 1-3 kJ of SBCAPE is expected to develop; therefore, there will be more than enough energy to get convection going, even if the forcing is somewhat lackluster. With the model hodographs having a veering profile with height, 0-3 km helicity between 100 and 300 m2/s2, and 0-6 km bulk shears of 45 to 60 kts, all of the severe threats would theoretically be on the table, the greatest being severe hail and winds. However, given that the CAMs are struggling still on the exact timing and placement of the convection, chances for convection over any one spot remain low (30% or so) across the U
P
That being said, the western half does have slightly better chances of seeing severe weather given the warmer temperatures over there and potentially higher SBCAPE. Thankfully, the severe weather threat drops off after the sun sets Sunday evening.

A stronger Clipper low is expected to move through the U.P. on Monday, bringing with it additional rain shower and thunderstorm chances. Because guidance is suggesting that (generally speaking)
the warm sector of the low will be over us during the morning hours, the severe weather threat will be significantly lowered due to the lack of diurnal heating creating CAPE; thus the better severe weather chances on Monday will be down in the Lower Peninsula. That being said, with up to around 1500 J of MUCAPE and 30 to 50 kts of bulk shear to work with, a low-end severe storm or two cannot be completely ruled out, even though some capping will need to be overcome above the boundary layer.

Expect generally quieter weather as we head into the rest of next week. With heights rising over the central CONUS during the mid-week before moving eastward heading towards the end of the week, we should see at least one day where we remain rain-free (most likely Tuesday or Wednesday). However, after the center of the high moves through, positively tilted flow over central Canada and the Northern Plains could set us up for additional Clipper shortwaves rotating into the area to end the forecast period.

AVIATION /06Z TAFS THROUGH 06Z SUNDAY/
Issued at 105 AM EDT Sat Jul 25 2026

VFR conditions likely hold until ~11-14z at CMX/IWD this morning when a weak cold front ushers in a round of scattered -SHRA, MVFR cigs, and potentially -TSRA (30-45% chance) from the west. With - TSRA threat diminishing, but not completely removed this morning, all TEMPO groups were lowered to PROB30 groups and the -TSRA windows were shortened. Removed -TSRA altogether at SAW where VFR likely persists the entire 6Z TAF period (75% chance). The MVFR deck is expected to scatter out around 18Z. Additional low chances (mainly <30% chance) for -TSRA return in the late afternoon at SAW with a lake breeze, but no mention was added with this TAF package as uncertainty is high. Otherwise SW winds hold steady this morning with a few gusts into the low 20 kt range. SW to W winds begin to taper down this afternoon with variable to calm winds tonight.

MARINE
Issued at 153 AM EDT Sat Jul 25 2026

Behind a dying cold front moving through the lake this morning, expect the southwest 20 to 30 kt winds over Lake Superior to diminish to 20 kts or less by this afternoon. Along the front, some showers and t-storms could be seen; while not expected, a stronger storm or two could occur over the western lake early this morning.
While light winds of 20 kts or less are expected to continue the rest of next week, some additional convection could be seen along the lakeshores on Sunday and over the whole lake again on Monday; while some severe weather could be seen over these two days, given the lack of SBCAPE over the water on Sunday and the warm-sector convection moving through mainly during the morning ours on Monday, the chance for severe weather remains low at this time (thinking 2% or less). Quieter weather looks to return for the middle of next week as high pressure builds over the central U.S. before sliding eastward.

MQT WATCHES/WARNINGS/ADVISORIES
Upper Michigan...
None.
Lake Superior...
None.
Lake Michigan...
None.