Area Forecast Discussion

KEY MESSAGES

- Warm moist airmass moving over Lake Michigan may bring a period of marine dense fog across our nearshore zones late tonight into Sunday morning, which could affect boaters. Patchy fog will also be possible over the lakeshore counties.

- Above normal temperatures persist for the next week. High temperatures in the 90s paired with increasing humidity will result in potential for moderate to major heat-related impacts.

- Next chance for widespread showers will be Monday into Tuesday.

DISCUSSION

Issued at 112 PM CDT Sat Jun 6 2026

Dry weather and above normal temperatures are expected for the rest of the weekend with a ridge of high pressure over the western Great Lakes region. Afternoon cumulus clouds are expected to dissipate this evening with the loss of daytime heating.

Fog...Hi-res models indicate the fog bank currently over Lake Michigan will track back westward later tonight into Sunday morning as winds turn easterly. The main concern is how far west this fog bank makes it as there are some suggestions it could make it as far as the bay of Green Bay and the lakeshore counties, while other models keep it mostly along the Lake Michigan nearshore waters. Given the higher certainty, will issue a Marine Dense Fog Advisory for the Lake Michigan nearshore zones and hold off for the Bay as well as hold off on a Dense Fog Advisory for the lakeshore inland counties. Models indicate this fog bank should push east on Sunday morning and dissipate entirely sometime Sunday afternoon across Lake Michigan.

Temperatures...Warming trend continues for next week as heat ridge builds and Hudson Bay high sets us up under southerly flow regime. Result will be a prolonged stretch of 90+ degree days, with little relief into the overnight periods. Confidence remains high (generally 60 to 90%) for seeing highs in the low to mid 90s Wednesday through Friday as ample moisture transport increases dewpoints solidly into the 60s and even 70s. As such, heat indices will largely read in the mid to upper 90s, with several readings in excess of 100 degrees possible across portions of central Wisconsin to the Fox Valley. Widespread major (level 3 out of 4) risk for heat-related impacts are forecast during this period, which would affect those without a means for cooling or hydration. Though still too soon to say with certainty, will need to monitor the potential for headlines as we head into early next week.

Rain chances...The next chance (60-80%) for widespread rain arrives Monday into Tuesday as a fairly potent shortwave migrates through prevailing southwesterly flow and up into the Midwest. Can expect some periods of heavy rain during this time as PWATs approach 2" (99th percentile), though any organized convection is not anticipated given the lack of upper support. Probabilistic guidance currently shows a decent signal (40 to 60%) for receiving 0.5" or rain over central Wisconsin through Monday night.

Accompanying the heat and humidity during the latter part of the week will be a reservoir of instability that builds over much of the upper Midwest. However, predictability for any rain/storm chances remains low this far out as mid-level ridge sits right overhead. Most of the ridge rider activity looks to stay off to our west, so convective initiation in our neck of the woods would likely hinge on smaller scale forcing mechanisms. This being said, cannot rule out periodic chances for some stronger diurnal storms given the magnitude of destabilization likely to occur during peak heating.

AVIATION

for 18Z TAF Issuance Issued at 1149 AM CDT Sat Jun 6 2026

FEW-SCT fair weather cumulus clouds are expected this afternoon, with bases around 5-6k ft. These clouds will dissipate this evening after sunset. Northwest winds of 5-10 knots, with gusts to 15 knots this afternoon will shift to the east at 5 to 10 knots this evening. Exception will be near KMTW, where a southeast lake breeze develops during the afternoon. East to southeast winds are expected on Sunday 5 to 10 knots with gusts to 15 knots.

GRB WATCHES / WARNINGS / ADVISORIES

None.