Cooler, less-humid weather arriving today; periods of storms this week

Sunday's high of 90 in the Twin Cities was the 20th time into the 90s this year, well above the average of 13 times. But all of that is over and done.

A cold front from the northwest is plodding southeastward across the state to spread cooler, much-less-humid air our way. Temperatures in northwestern Minnesota fell into the sweatshirt-worthy low 40s Monday morning.

Sept 17 = Mon fcst map
Forecast surface weather map for Monday. NOAA Weather Prediction Center

High temperatures Monday will be just in the 60s across northern Minnesota but will reach the mid 70s to mid 80s for southern parts of the state until the front passes through. The Twin Cities should reach about 80 degrees.

That cold front will combine with disturbances aloft to generate rounds of thunderstorms this afternoon and evening. More storms are likely to develop tonight as the usual nocturnal low level jet stream revs up.

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The expected thunderstorm will be accompanied by a marginal risk of severe weather for central and southern Minnesota.

Sept 17 - svr US
A marginal risk of severe weather is posted from southern into central Minnesota Monday and Monday night. NOAA Storm Prediction Center

Florence update

As you might have noticed on today's forecast map, heavy rains from Tropical Depression Florence will continue to soak and flood large areas from the Southeast northward as it makes a turn gradually toward the north and then northeast. The risk of more flash flooding Monday is significant from North Carolina to New York State.

Sept 17 - 24 hr flash flood risk
The risk of flash flooding during the 24 hours ending at 7 a.m. on Tuesday. NOAA Weather Prediction Center

Cooler the rest of the week, with storms

Temperatures will feel much more like normal September weather for the rest of the week. By Friday, the Twin Cities might have a high temperature just in the upper 60s.

Scattered showers and thunderstorms are likely on Tuesday, mainly across the southern half of the state. Expect widespread showers and thunderstorms beginning on Wednesday and lasting well into Thursday.

Sept 17 - Wed vcst map
Forecast surface weather map for Wednesday. NOAA Weather Prediction Center

Possible flash flooding

Some rounds of heavy rain from today through Wednesday night and into Thursday will produce the risk of excessive rainfall, which is a scientific way of saying that flash flooding is possible.

Sept 17 - excessive rainfalls
Forecasts of possible excessive rainfalls this week. Twin Cities National Weather Service

As of now it looks like the greatest rainfall totals are likely to be in southwestern and south central Minnesota.

Sept 17 - 4 day rainfall
Forecast possible rainfalls through Thursday. Twin Cities National Weather Service

The big rainfall picture

The five-day precipitation forecast clearly shows the expected heavy rain for southern Minnesota and northern Iowa as well as the continued heavy rains and potential for flooding in the East.

Sept 17 - 5 day QPF
Forecast 5-day rainfall ending at 7 a.m. Saturday. NOAA Wetaher Prediction Center