Heaviest rainfall focusing on southern Minnesota Thursday and Friday

Doppler radars will be getting a workout again Thursday and Friday across Minnesota.

A low-pressure system will cross the Upper Midwest Thursday and Friday. That will trigger two or three rounds of scattered storms.

Wednesday’s forecast model runs suggest the heaviest rainfall signal is setting up across southern Minnesota, with the Twin Cities riding the edge of multi-inch rainfall totals.

Here’s a look at the latest model trends on rainfall timing and totals through the weekend.

Thursday and Friday

It looks like the first wave of rain and thunder will move into southwestern Minnesota Thursday morning. There is a lot of forecast model divergence on storm timing and coverage Thursday.

The National Oceanic and Atmospheric Administration’s Weather Research and Forecasting model seems to have the most reasonable fit to my eye. It develops a potentially severe storm cluster in southwestern Minnesota Thursday morning and tracks it across southern Minnesota.

The highest severe risk would be along and north of the Interstate 90 corridor. Under this scenario, the northern edge of this complex would just clip the greater Twin Cities area in the late morning hours Thursday.

The second and third waves of rain with this system would likely arrive Thursday night into Friday morning and again Friday afternoon. Here’s NOAA’s North American Mesoscale Forecast System 3 km resolution model through 7 p.m. Friday:

Rainfall totals

Again, rainfall totals look to be heaviest across southern Minnesota. The latest forecast model trends I respect suggest less than an inch across northern Minnesota with a wide band of 1 to 3 inches across central Minnesota, including the Twin Cities area.

The most likely zone for 2- to 4-inch rainfall totals favors southern Minnesota, including Rochester, Winona and the La Crosse, Wis. areas.

Here’s NOAA’s Global Forecast System rainfall output through Friday:

Here are the latest Twin Cities National Weather Service rainfall projections:

Another front will bring scattered rain and thunder late Saturday. This system could bring an inch or more of rainfall to the northeast Minnesota fire zones.

Here’s the European Centre for Medium-Range Weather Forecasts model total rainfall output through Sunday:

Note that the spatial coverage differs from NOAA’s American GFS models. That’s typical with summertime rain systems.

Stay tuned as forecast models try and refine timing and totals into Thursday.