SHORT TERM
Issued 301 AM CDT Sat Jul 27 2024

Today through Sunday night:

Patchy fog in low-lying areas will clear rapidly into this morning. Otherwise, breezy southerly winds and mostly clear skies today will allow temperatures to climb into the mid-80s away from Lake Michigan. A lake breeze is expected to develop in the afternoon and drop temperatures near the Lake back into the mid to upper 70s.

Cloud cover will increase overnight as an upper level low and associated WAA progress into southern Wisconsin. This will serve to keep low temperatures in the mid-60s. A few showers may develop during the late overnight hours to the early morning hours on Sunday as mid-level WAA and Gulf-origin moisture push into far southern Wisconsin.

Weak shear around 20 kt and CAPE values of 500 to 750 J/kg imply severe threat is minimal on Sunday. However, strong WAA and a decaying, closed upper level low lifting into southern Wisconsin will provide enough lift to produce showers and thunderstorms throughout the afternoon. Activity generally looks to be scattered, although in some areas the slow-moving nature of these thunderstorms may result in longer duration rainfall in localized areas. Rainfall may also be heavy, as PWAT values near 2 inches. Outside of rain and storms, expect high temperatures in the low to mid-80s and southerly breezes.

Showers and storms may linger into the overnight hours Sunday, but will lose instability into the evening hours. Still, lift remains in place with the upper level low through the late overnight hours before exiting to the east. Therefore, remaining showers and storms will end from west to east during the late overnight hours. Lows in the upper 60s and southerly winds are expected through the overnight hours.

MH

LONG TERM
Issued 301 AM CDT Sat Jul 27 2024

Monday through Friday:

Upper level ridging in the central to southern Plains will nose into the Upper Midwest next week, leading to rising temperatures and humidity, as well as putting southern Wisconsin into the path of ridge-riding shortwaves once again. Plenty of warmth and humidity will set the stage for instability to build in between rounds of storms. Although confidence in placement and timing of these shortwaves remains low at this time, confidence in a more active pattern has continued to increase with consistency in modeling continuing. Therefore kept NBM PoPs of generally 20 to 40 percent through the week. PWATs of 1.5 to 2 inches are indicated on major models through the week as well, indicating heavy downpours with any thunderstorms that do develop.

With building ridging, heat becomes a concern once again across southern Wisconsin. Heat index values in the mid 90s are possible by midweek.

MH

AVIATION
Issued 301 AM CDT Sat Jul 27 2024

Light to calm winds early this morning will become southerly around 10 kt by mid morning. A few southeasterly gusts between 15 and 20 kt are possible along lakeshore terminals this afternoon as a lake breeze pushes inland. Clear skies are expected, with a few diurnal cumulus around 3000 ft developing around midday. Winds and cloud cover diminish into the evening hours, with high clouds moving in around 10 kft across southwestern Wisconsin late tonight. Cloud cover will increase through the overnight hours, with rainfall and lower ceilings developing into the morning hours Sunday.

MH

MARINE
Issued 301 AM CDT Sat Jul 27 2024

High pressure will continue to retreat into the Northeast today, while low pressure moves from northern Saskatchewan into northern Manitoba. South winds will gust around 20 knots, mainly across the north half. On Sunday, low pressure will develop in the central Plains and south breezes will continue as a warm front develops across the Lake. Weaker low pressure will move across the lake early Tuesday, shifting winds to southwesterly. Thunderstorms are possible throughout Sunday, with additional thunderstorm chances continuing through midweek.

MH

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