NWS 8-27-18

Severe storms, heavy rainfall and high temperatures in south-central Wisconsin on Monday could turn up the anxiety level on Madison's Isthmus, where many streets are under water.

The National Weather Service is looking at the chance for storms and heavy rain later in the day into Monday night, with heat index values reaching the mid- to upper 90s, maybe 100 in southeast Wisconsin.

A flood warning remains in effect in Madison to 4:30 p.m. Monday, because of the flooding caused by allowing water to flow through the Tenney dam from Lake Mendota into the already water-filled Yahara River and Isthmus storm sewers.

"Rainfall since Sunday afternoon of a half-inch to an inch may have resulted in additional flooding across the area," the Weather Service said.

Monday's high is expected to reach 87, and the overnight low only dropping to 73.

Tuesday's forecast is worse than Monday.

27 Storm Track meteorologist Branden Borremans said showers and thunderstorms, some strong, will develop by mid- to late afternoon, with the heat index rising to the mid-90s.

Rain is forecast to continue Tuesday night. The Weather Service said Madison could see up to 2 1/2 inches of rain by Wednesday morning.

The heat, rain and humidity should end Wednesday, with skies becoming mostly sunny and a high of 69 in the forecast.

Sunshine and highs in the 70s are forecast for Thursday and Friday, with a chance for showers and thunderstorms late Friday night into Saturday.

Saturday should see increasing sunshine and a high near 78, then Sunday should be nice with sun and a high near 76.

Sunday's high of 87 was 9 degrees above normal and 8 degrees below the record high of 95 for Aug. 26, set in 1953.

The low on Sunday was 61, 3 degrees above normal and 22 degrees above the record low of 39 for the date, set in 1964.

Heavy storms dropped 0.83 inches of rain on the airport Sunday, bringing the August rainfall total up to 9.30 inches, 5.69 inches above normal.

The record rainfall on Aug. 26 was 2.28 inches in 1986.

For the meteorological summer of June through August, Madison has received 18.09 inches of rain, 5.76 inches above normal.

Since Jan. 1, Madison has received 34.93 inches of precipitation (rain and melted snow), 10.77 inches above normal.

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