UPDATED 10:30AM - State Rainfall Record Broken in Cross Plains Wisconsin
By Justin Poublon
August 21, 2018 - 10:30 AM CST | 614 0
Record setting "extreme" rainfall occurred on the west side of Madison last night according this NWS situation report.
The report goes on to say, "There were a number of reports of 10-13 inches from just north of Verona to Middleton to Cross Plains along US Highway 14. Reports from Cross Plains to Black Earth are that these areas are completely submerged. Large rescue effort ongoing to evacuate people to higher ground."
Rain started on Monday, Aug 20 at around 2:00PM and continue into the overnight hours ending early Tuesday morning.
At 9:20 AM 15.33" was reported out of Cross Plains, WI setting a new 24hr rainfall record for Wisconsin. The previous record for 24hr precipitation was 11.72" at Mellon in 1946.
Like the flooding event last week in Watertown, this event featured a pronounced 500mb height anomaly moving slowly across the state. There are many meteorological aspects to the system but the one that sticks out is that this was an abnormally strong vertically stacked low pressure system for August. This system was stronger than it's predecessor.
Here are the official storm reports as of 10:30AM.
Here is the radar loop of the event.