Marine Weather and Tide Forecast for Marinette, WI

DISCUSSION
Issued at 233 PM CDT Mon Apr 28 2025

Short Term...Tonight and Tuesday

Scattered elevated convection has develop across central WI this afternoon as mid-level lapse rates have steepened. Radar returns are indicating some non-severe hail is occurring with in these storms. Expect these pulse-type storms to grow in coverage over the next few hours, however, the likelihood that any cells become severe is low, as the greatest SBCAPE values remain along and west of the 1- 35 corridor in central MN and RAP analysis soundings still show a strong cap around 850mb.

CAMs continue to show the best window for severe thunderstorm initiation between 00-02Z as the cap erodes. Strong moisture advection will create a much more unstable atmosphere as a warm front currently draped across southwest WI moves north and east.
Initially discrete supercells will be possible across central WI as storms initiate. SBCAPES increasing to 100-1500 J/kg along with strong low-level (0-1km) shear 30-35kts (SRH 290 m2/s2) does point to a potential tornado threat with any storms that do develop. Steep mid-level lapse rates also bring severe hail, up to 2" into play with the strongest storms. As the event progresses and a cold front starts to push into the western part of the forecast area storms are forecast to grow upscale into a QLCS. As this occurs damaging severe winds gusts along with embedded tornados will become possible. If an organized QLCS is able to develop it will likely remain severe as it moves east across the region, however, storm intensity may start to weaken as they approach Lake Michigan. The severe weather threat is expected to end around or just after midnight.

Behind the cold front there may be some lingering thunderstorms Tuesday morning, but the risk for any severe storms at that time will be low. Winds behind the front also look gusty for Tuesday with peak gusts reaching 30-40 mph.

Long Term...Tuesday Night Through Monday

Tuesday-Monday:

Cooler conditions are expected on Tuesday in the wake of the surface cold front as Canadian high pressure builds into the area.
Instability quickly wanes as drier air works in, but a few showers remain possible as a mid-level shortwave trough swings through.

Otherwise, broad troughing will overspread the area later in the week as northern/stream shortwave troughs transect the central US.
Although details of this system are somewhat unclear, rain chances increase by Thursday (40-80%), with chances lingering into Friday.
Trends favor the area being on the cooler side of this system, keeping any severe weather potential farther south.

The pattern looks to trend drier heading into the weekend as mid- level ridging builds across the central US downstream from large scale trough development across the western US. Trends favor a return to above average temps in this regime.

AVIATION
for 18Z TAF Issuance Issued at 103 PM CDT Mon Apr 28 2025

Morning storm activity is waning with clouds beginning to clear out south of a RHI to MNM line. Clear should continue through the early- afternoon as a warm front lifts north into the region.

Attention then turns to the next round of thunderstorms forecast to develop late this afternoon through the evening. There are still question regarding the strength and coverage of these storms, however, there is an increasing risk for strong to severe storms, particularly across central WI between 01-04Z. Any storms that do develop may be capable of producing strong winds gusts over 40kts, hail over 1", and a tornado. Intense downpours may also drop vsbys to MVFR/IFR at times.

LLWS is expected across much of the area through Tuesday morning, due to a low-level jet increasing to 50 to 55 kts. Surface winds will also be strong, with south winds gusting to 25 to 30 kts this afternoon/evening, then turning west to northwest as the front move through the northwest part of the forecast area late tonight.

GRB WATCHES/WARNINGS/ADVISORIES
None.