Minnesota monsoon: flash flood and severe risk today

Welcome to the Minnesota monsoon.

Here's the recipe for tropical downpours today and a slight risk for severe storms.

• A tropical air mass with dew points near 70 degrees.

• A slow moving frontal boundary sliding slowly south.

• Solar heating, even through cloud cover to boil the ripe air mass overhead into storms.

'Heavy rainers'

Combine these ingredients and you get scattered storms today with the capability of producing torrential multi-inch rainfall totals. Expect more widespread 1- to 3-inch rains today, with the potential for locally 3 to 6 inches by tonight, especially south of the Twin Cities toward the Interstate 90 corridor. Flash flooding is a threat today in southern Minnesota.

Active afternoon

The atmosphere will become increasingly feisty over Minnesota this afternoon. Spotty storms will bubble up in the unstable air mass this morning. Then the heat of the day will trigger stronger and more widespread storms this afternoon. The National Oceanic and Atmospheric Administration's North American Mesoscale Forecast System 3 km resolution model paints clusters of strong to severe storms over the Twin Cities and southern Minnesota this afternoon.

Flash flood risk

We've already seen many 2- to 3-inch rainfall reports from last night. NOAA's Global Forecast System model paints the possibility of another 3 to 6 inches-plus rainfall for parts of southern Minnesota by Friday evening. The flash flood risk is there, especially south of Minneapolis-St. Paul toward Rochester.

Stay tuned for additional watches and warnings today.