Flood watch: Periods of heavy rain, thunder into Saturday

Drier pattern looks to take hold next week

flood pivotal
A flood watch is posted for much of southern Minnesota through Saturday morning.
National Oceanic and Atmospheric Administration, via Pivotal Weather

We’ll have periods of potentially excessive rainfall and thunder into early Saturday, some of it heavy with flooding potential. Next week looks drier overall.

Periods of rain and thunder into Saturday

A flash flood warning is posted for portions of Blue Earth and Nicollet counties through 2:30 PM Friday:

Flash Flood Warning

National Weather Service Twin Cities/Chanhassen MN

1140 AM CDT Fri Jun 21 2024

The National Weather Service in the Twin Cities has issued a * Flash Flood Warning for...

  Central Blue Earth County in south central Minnesota...

  Southeastern Nicollet County in south central Minnesota...

* Until 230 PM CDT.

* At 1140 AM CDT, Doppler radar indicated thunderstorms producing heavy rain across the warned area. Between 1 and 2 inches of rain have fallen. The expected rainfall rate is 1 to 1.5 inches in 1  hour. Additional rainfall amounts of 1 to 3 inches are possible in the warned area. Flash flooding is ongoing or expected to begin shortly.

flash flood
Flash flood warning for Blue Earth and Nicollet counties through 2:30 PM
National Weather Service

A flood watch is also posted for southern Minnesota through Saturday morning due to the potential for flash flooding from excessive rainfall. 

Heavy rain fell overnight in southwestern and south-central Minnesota. Several locations reported 4 inches with more than 7 inches nearby in southeastern South Dakota.

rainfall 9a
24-hour rainfall reported through 9 a.m. Friday
National Weather Service

We’ll have scattered periods of showers and thunderstorms, some of which will be heavy with locally heavy rainfall. Much of midday and afternoon Friday will see more widely scattered activity before more storms fill in across southern Minnesota late afternoon into Friday night.

fri-sat prec 9a
Forecast precipitation 8 a.m. Friday through 10 a.m. Saturday
NOAA, via Pivotal Weather

In addition, there’s a slight risk (level 2 of 5) for severe weather mainly in the southern third or so of Minnesota.

fri spc 9a
Severe weather outlook for Friday into Friday night
NOAA Storm Prediction Center, via Iowa State University

There could be several additional inches of rainfall in southern Minnesota with potentially locally heavier amounts. Below is the official National Weather Service forecast for rainfall 7 a.m. Friday through 7 p.m. Saturday.

addl rain
Additional rainfall Friday into Saturday
National Weather Service

Some of the most recent morning computer model runs are trending a bit more south with the heaviest rainfall. It’s still a question as to whether the heaviest rainfall shifts that far south. This is just one model. We’ll be watching how things develop later Friday very carefully.

HRRR compare
High-Resolution Rapid Refresh model run for overnight Friday into Saturday morning
NOAA, via Pivotal Weather

There’s also a slight risk of severe weather (level 2 of 5) for southeastern Minnesota Saturday into Saturday night.

sat spc
Severe weather outlook Saturday into Saturday night
NOAA Storm Prediction Center, via Iowa State University

Most rain should taper off Saturday morning with mostly dry weather Sunday and Monday. We’ll also see warmer temperatures in the upper 80s by early next week and an overall drier pattern, thankfully. 

Rising rivers

In addition to flash flood concerns in the near-term, rivers are continuing to rise into next week. How much rain and where in the next 24 hours will be critical to these forecasts.

The Mississippi River at St. Paul for example is forecast to reach a level that would be the highest in 23 years, beating 2019 crests. Regardless, major flood stage is forecast to be reached by Tuesday.

River level forecast for the Mississippi River at St. Paul into next week
National Weather Service