On Monday evening, a boundary that was laid across northern Minnesota and Wisconsin by overnight convection was a forcing mechanism and a steering mechanism for heavy rainfall. The region saw multiple rounds of convection throughout the day, and this rainfall trained over the region for hours.
The environment was prime for crazy amounts of rainfall across the region. A boundary laid across the region provided additional lift to the ascent within the atmosphere seen within other atmospheric diagnostics.
This boundary was overlaid by a large pool of highly anomalous precipitable water values going on 2.2″. The evening sounding out of Minneapolis showed PWAT values of 1.98″, and the max moving average for July 12 at 00z is only 1.88″. The atmosphere present across central and northern Minnesota and northwestern Wisconsin was historically anomalous.
This led to anomalously high rainfall in a short period of time, but also significant flash flooding. Some of the rainfall in a 24 hour timespan across northern Minnesota and northwestern Wisconsin totaled greater than 10″.
— Mark Tarello (@mark_tarello) July 12, 2016
— Jayson Prentice (@SeverePlains) July 12, 2016
Check out some of the wild images out of the region, and some of the peaks from rivers across the region.
— Danlure (@danlure) July 12, 2016
— St. Cloud Times (@sctimes) July 12, 2016
— Aaron White (@AaronWhiteTV) July 12, 2016
Flooding events like these are never good, so keep these folks in your thoughts and prayers as they go through it.