Marine Weather and Tide Forecast for Bayside, WI

SHORT TERM
Issued 305 PM CDT Wed Apr 23 2025

Tonight through Thursday night:

A period of descending motion following the departure of this morning's weak MCV has left a window for sunshine to gradually steepen the low-level lapse rates (which are currently poor, as evidenced by the general lack of fair wx cumulus clouds). A few isolated showers or even a weak storm may form in far southern WI (near the IL border) over the next few hours, but will be limited by the poor thermodynamics in the wake of this mornings convection. Instead, the main area we are watching is the cumulus field evident on satellite in northeast Iowa, any convective initiation that occurs in that region is likely to drift eastward later this afternoon into this evening, impacting our region after low level lapse rates have steepened in the sunshine. The current forecast for late this afternoon into this evening currently features 15-35% chances for thunderstorms (highest further west), though this could be increased if favorable timing / upwind-placement of initiation in Iowa / southwestern WI occurs.

If this scenario were to play out, we'd be working with an environment of 40-50kt effective wind shear (mostly aloft, shallow shear and helicity are relatively weak), with steep low and mid-level lapse rates. This would create some cellular or line-segment storms with a threat for gusty winds and hail, with a few strong to severe storms possible. There may be enough helicity aloft for a few storms to rotate (thus contributing to hail and wind being the main concerns), but low-level helicity integrals are not looking impressive. That, coupled with the development of the NBL later this evening will limit tornadic potential.

Showers / thunderstorms may linger into Thursday morning, followed by a lull in the activity mid-Thursday / Thursday afternoon. East to northeast winds through this time will hold daytime high temps to the 50s, but allow highs in the upper 60s to low 70s further west. Widespread showers with potential for some rumbles of thunder then expected late Thursday evening through Friday morning as a weak low pressure system crosses the region.

Sheppard

LONG TERM
Issued 344 PM CDT Wed Apr 23 2025

Friday through Wednesday:

The 12Z GEFS and 12Z ECMWF show fairly good agreement with the track of a wave of low pressure and shortwave trough aloft from srn IA to se Lower MI during the day on Fri. Widespread showers and isold thunderstorms will move across srn WI during this time. Nly winds and cold advection will then develop for the afternoon and night.

A large high pressure area will then shift across WI for Sat-Sat nt with 500 mb height rises ahead of the upper ridge over the Great Plains. A nice day with temps slightly below normal is forecast.
The high will shift east for Sunday with lgt sly winds and warm advection beginning as the upper ridge nears. High temps will rise into the upper 60s well away from Lake MI.

Breezy sly winds and warm, moist advection will then increase Sun nt- Mon as low pressure over the intermountain west moves into the nrn Great Plains and eventually nrn MN. There will likely be a round or two of showers and storms within a warm, humid airmass. Another round of showers and storms would likely occur Mon nt ahead of the approaching cold front that will pass on Tue, with less activity along the front on Tue. High pressure will then arrive for Wed.

Gehring

AVIATION
Issued 305 PM CDT Wed Apr 23 2025

Fair wx cumulus clouds (lower altitude) building into the region, generally remaining over 4000 ft (VFR). Some slight potential for periods of MVFR ceilings associated with a ~35% chance for showers and thunderstorms later this afternoon into this evening. A few strong to severe storms with hail and wind gusts will be possible. Generally light and variable winds (due to a stalled frontal boundary) overnight.

Shower / thunderstorm chances continue into Thursday AM before dissipating, leaving a lull for Mid Thursday into the afternoon hours. East winds expected on Thursday, with northeast winds for terminals in Lake Michigan counties.

Sheppard

MARINE
Issued 305 PM CDT Wed Apr 23 2025

A weak cold front will work across the open waters of Lake Michigan tonight, allowing winds to shift out of the north- northeast by daybreak. North to northeast winds will continue through Thursday night as high pressure of 30.4 inches builds into the northern Great Plains. Low pressure near 29.9 inches will cross southern Lake Michigan on Friday, bringing gusty northerly winds to the open waters. Gales appear unlikely at this time, though trends will be monitored in the coming forecasts. Breezy conditions will continue through Saturday, with winds tapering Saturday night as 30.4 inch high pressure builds in from the northern Great Plains.

Quigley

MKX WATCHES/WARNINGS/ADVISORIES
WI...None.
LM...None.