A frost advisory has been issued for the Milwaukee area; rain expected later this week
Near-record heat may have been the theme in Wisconsin last week, but the first frost of the season and a few inches of rain are in the forecast for the Milwaukee area this week.
The first frost of the season arrived in Milwaukee Monday morning as National Oceanic and Atmospheric Administration sent out the first frost advisory of the season. The crystalized water droplets were seen throughout the region, especially inland from Lake Michigan where temperatures are usually colder.
NOAA Meteorologist Mark Gehring said when temperatures cool at night and there is moisture in the air, condensation can occur on the ground. The water vapor in the air then turns to water droplets. When it's cold enough, the droplets turn into ice crystals on the grass.
"This is what happens with cloud formations, too," Gehring said.
A frost advisory is not to be confused with a freeze advisory, which occurs when the temperature actually dips below freezing, or 32 degrees Fahrenheit. A frost advisory is issued when frost is visible on the ground.
"When we put out a frost advisory in early October, one thing we want to do is let the public know to bring their flowers inside if they still want them," Gehring said.
He added that sometimes early frosts or freezes can affect crops while they're still in the mature stage. That is more so if this occurs in September. In early October, farmers are normally already harvesting or preparing to harvest when their crop dries out.
Moreover, the first freeze might not be far off. The median timeframe that the Milwaukee area sees its first freeze of the season is between Oct. 21 and Oct. 31.
While the cooler weather is here to stay, it'll be accompanied by some much-needed rain in the area starting on Wednesday evening. Gehring said that a low pressure, slowing area is forecast to move into the area from the central Great Plains region and should bring on-and-off rain through at least Saturday with a chance of rain for Sunday. This will likely bring two to four inches of precipitation to the area.
The Milwaukee area could see less rain if the rain moves north. In that situation, the area could see less than 2 inches.
“We do need this rain,” Gehring said. “It would be nice to recharge the soil before going into winter and get some water in the rivers and lakes, as well.”
More: Some Wisconsin trees are changing color early this year. Here's why.
Drew Dawson can be reached at ddawson@jrn.com or 262-289-1324.
This article originally appeared on Milwaukee Journal Sentinel: Milwaukee weather: Frost advisory issued, 2-4 inches of rain to come
