Marine Weather and Tide Forecast for St. Francis, WI

UPDATE
Issued 1243 PM CDT Wed Jun 18 2025

A shortwave trough now moving into wrn IL will continue to nrn IN by 00Z, while the sfc low will deepen slightly to 1003 mb as it reaches the srn tip of Lake MI at a similar time. The arching band of strong convection over ern IL will track newd into IN on the nose of a LLJ. Thus the strongest convection will miss S WI.
Over srn WI, PVA and weak low to mid level frontogenesis will continue to produce efficient showers and isolated storms into this evening. MLCAPE around 500 J/KG will support the isold storm potential, but moist soundings and PWs of 1.5-1.7 inches will make for efficient rainfall rates. Thus will maintain the potential for urban and small stream flooding into this evening.

Later tnt a mid level shortwave trough currently over srn MN will track sewd across srn WI, which will keep intermittent showers and still efficient rain producers over the area. The showers may linger briefly beyond 12Z Thu followed by partly cloudy skies with temps returning to the lower 80s for much of S WI. A few showers or storms over central WI Thu afternoon and night could move into the MQT County area ewd to Sheboygan County via a developing warm advection pattern over central WI.

Gehring

SHORT TERM
Issued 255 AM CDT Tue Jun 17 2025

Today through Thursday:

Based on the latest CAMs through the morning hours we should expect relatively ongoing precip chances across parts of, if not most of southern WI as the front and associated PVA aloft hang in the region through the mid morning ahead of the approaching surface low and associated upper trough. Models indicate the potential for a very brief lull in widespread precip chances between the departing precip from overnight activity by the mid to late morning to the activity associated with the surface low closer to noon.

The latest forecast information suggests the stronger storm potential as the low approaches has really shifted south of the CWA for the afternoon as the trajectory of the surface low is now into northern IL and thus we will not see any real southerly winds with mostly east to northeast flow across the entire CWA
With the lake still being fairly cool this also plays as an inhibitor for storm chances. CAMs really support this update as well with limited storm activity and largely widespread showers expected. This system has actually shift far enough south that there is now increased uncertainty in how much rain the northwest parts of the CWA may get as several models show that area being drier than originally expected.

We cannot rule out storms as there should be at least enough instability to bring some lightning but the track of the low really puts a dampener on any severe potential. If there are slight deviations north in the forecast track that could reintroduce some severe risk but overall the risk remains fairly low at this point.

Into Thursday, there originally looked to be some potential for storms associated with some upper level shortwave activity on the backside of the departing trough. While that remains the case the moisture associated has decreased on the south side of the state and the better forcing has shifted further north.
While we cannot rule out lingering showers into Thursday morning from the departing low the chances for additional showers/storm activity into the afternoon has certainly decreased. Shifts in the forecast may still occur with east central WI having the best chance for storms Thursday afternoon/evening but potential has decreased with the latest model information but there are a few models that still show some potential in the area Thursday afternoon, such as the RAP.

Kuroski

LONG TERM
Issued 255 AM CDT Tue Jun 17 2025

Thursday night through Tuesday:

The upper-level ridge begins to build in across the Upper Midwest into Friday. The core of the heat will be to the west of the Mississippi River Friday, but still looking at above normal temps topping off in the 80s and increased dewpoints in the mid to upper 60s (a.k.a muggy). Thus will feel closer to 90F in some spots for Friday. Will also see sporadic thunderstorm chances beginning Friday morning given the warm and muggy conditions paired with the large swath of low-level WAA. Additional thunderstorm chances are progged for Friday evening as the nose of a 40-50 kt LLJ pushes into the area. Cannot rule out a stronger storm or two given the LREF members hinting at +1500 J/kg of CAPE and modest deep layer shear of 35-40kt.

Saturday and Sunday will continue to see the upper-level ridge axis slide east across the Upper Great Lakes. This will bring continued heat to southern WI with high probabilities of temps in the 90s.
Again given hints of a stiff southwesterly flow and the trend of hot and muggy conditions, can easily see heat indices int the mid to upper 90s and even crack the 100F at times through the weekend. If this trend continues with the temps/heat indices, may need to consider headlines highlighting the heat related impacts.

Models do have the heat lingering into the start of next week, but hint at the upper-level ridge flattening as a trough digs across the northern Plains. This in turn would bring a cold front down across the Upper Midwest and provide a bit of relief from the weekend heat more into Tuesday. However, uncertainty on this cold front remains given how far out it is and the potential for timing and location of its track to change.

Wagner

AVIATION
Issued 1243 PM CDT Wed Jun 18 2025

AReas of MVFR Cigs and Vsbys over S WI this afternoon and tonight with fairly widespread showers and isolated storms expected. Local Cigs below 1 kft at times as well as 1-2SM with the heavier showers or storms. Low stratus will become scattered by late Thu AM. VFR conditions afterward.

Gehring

MARINE
Issued 1243 PM CDT Tue Jun 17 2025

Low pressure around 29.7 inches over western IL will move to the southern tip of Lake Michigan by early evening, then to southern Lake Huron late tonight.

Light and variable winds will become modest north to northwest winds after the low passes by early this evening. Light north to northwest winds Thursday morning will then back to southwesterly for Thursday afternoon into Friday. Breezy southerly winds can then be expected for the weekend as strong low pressure develops over the Dakotas.

Gehring

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