A bubble of hot, humid air associated with sprawling high pressure is expected to build into the Upper Midwest from the central Plains over the weekend. Typically, when a large area of high pressure sits over a region for an extended period of time in the summer, it causes hot, dry air to sink to the ground. As the air sinks, it warms even further. In addition, since the center of high pressure areas are usually cloud-free, the direct sunlight further raises daytime temperatures.
Beginning Sunday and continuing through Thursday, southern Wisconsin will be on the northern fringe of this building large high pressure area. Daytime temperatures are expected to reach the upper 80s to middle 90s away from Lake Michigan for much of the period. Lighter surface winds will allow a lake breeze to develop most days, keeping lakeshore areas cooler.
South to southwesterly breezes will usher in humid air and warm dewpoints during this time as well. Much of this time, the dewpoint will remain in the 70s, creating sultry, humid conditions during the day and muggy conditions at night.
The combination of warm temperatures and high humidity will cause the heat index to rise to between 98 and 108 degrees over south central into portions of southeast Wisconsin most afternoons. The hot and humid conditions are expected to linger across the region for much of next week.
Overnight temperatures will only fall to the low to mid 70s for much of this time due to the high humidity. This nighttime heat contributes to heat stress because your body has no relief from the oppressive conditions. The heat stress continues to build as the hot conditions continue.
One caveat is that a cool front is expected to slip southward across Wisconsin and Lake Michigan Monday night and early Tuesday. This front may cause more clouds, stronger southeast winds and precipitation which would result in slightly cooler temperatures over more of southeast Wisconsin on Tuesday.
Beginning Sunday and continuing through Thursday, southern Wisconsin will be on the northern fringe of this building large high pressure area. Daytime temperatures are expected to reach the upper 80s to middle 90s away from Lake Michigan for much of the period. Lighter surface winds will allow a lake breeze to develop most days, keeping lakeshore areas cooler.
South to southwesterly breezes will usher in humid air and warm dewpoints during this time as well. Much of this time, the dewpoint will remain in the 70s, creating sultry, humid conditions during the day and muggy conditions at night.
The combination of warm temperatures and high humidity will cause the heat index to rise to between 98 and 108 degrees over south central into portions of southeast Wisconsin most afternoons. The hot and humid conditions are expected to linger across the region for much of next week.
Overnight temperatures will only fall to the low to mid 70s for much of this time due to the high humidity. This nighttime heat contributes to heat stress because your body has no relief from the oppressive conditions. The heat stress continues to build as the hot conditions continue.
One caveat is that a cool front is expected to slip southward across Wisconsin and Lake Michigan Monday night and early Tuesday. This front may cause more clouds, stronger southeast winds and precipitation which would result in slightly cooler temperatures over more of southeast Wisconsin on Tuesday.