A winter storm hit parts of the northern U.S. this week, breaking scores of snowfall records in Montana, Iowa, and Minnesota, where more than 1 100 road accidents were reported due to heavy snow. A deepening upper-level trough and a surge of cold Canadian air now set the stage for yet another early-season winter storm and more rounds of snow through early next week, possibly as far south as Texas.
Montana was the hardest hit, with up to 35 cm (14 inches) of snow through Monday, October 19, setting a number of October snowfall records.
This included the heaviest daily October snowfall of 20.8 cm (8.2 inches) on Sunday, October 18; greatest October snow depth of 25.4 cm (10 inches) on Monday, breaking the previous record set in 2019; earliest-in-season snow depth, the previous record was set on November 9, 2012.
Two rounds of snow covered parts of Iowa. On Sunday, Des Moines recorded its second earliest snow on record (since 1885). On Monday, central and eastern Iowa registered up to 22.9 cm (9 inches) of snow-- the snowiest October day on record in Ankeny.
Here's a list of snowfall totals so far as of 5:30 pm.— MPR Weather (@MPRweather) October 20, 2020
Granite Falls 8.3"
Northfield & St. Cloud 6.4"
Columbia Heights 5"#mnwx pic.twitter.com/Vpuz329oQm
#Snow has tapered off a bit this afternoon here at the office for now as we get ready to launch our afternoon weather balloon. What do you see at your location? #MTwx #MTsnow pic.twitter.com/53uElq7HzI— NWS Great Falls (@NWSGreatFalls) October 18, 2020
Tuesday's snowstorm was the largest early-season storm in the state of Minnesota in 140 years. WCCO-TV meteorologist Chris Shaffer said this was also the second-largest snowfall in October, following the 1991 Halloween snowstorm.
Lakeville registered 22.8 cm (9 inches) of snow, Granite Falls 22.6 cm (8.9 inches), Red Wing 20 cm (8 inches), Minneapolis−Saint Paul Airport 18.8 cm (7.4 inches).
More than 1 100 crashes and spinouts were reported across the state. Dozens of people sustained injuries, but there were no casualties.
Power was disrupted for more than 33 000 residents. By late Tuesday, more than 8 000 remained without electricity.
"Following on the heels of Tuesday's snowstorm in the Upper Midwest, a deepening upper-level trough and a surge of cold Canadian air sets the stage for yet another early-season winter storm," NWS forecaster Mullinax noted.
Snow showers are forecast to develop from the northern Rockies to portions of the Dakotas later on Wednesday, October 21.
As a developing surface low pressure system strengthens in the northern High Plains late Wednesday into Thursday, snowfall coverage will expand throughout the northern Rockies and Plains with the heaviest totals likely to occur in the northern Absaroka Range and the Bighorn Mountains.
There is also a chance for significant snowfall to occur Thursday, October 21 in portions of the Dakotas and northern Minnesota where more than 20 cm (8 inches) is possible.
"Expect treacherous travel conditions and poor visibilities in these affected areas along with much below normal temperatures lasting into Friday," Mullinax said.
Some daily record cold highs/lows are possible in these areas through Friday, he added.
The plunging temperatures are forecast to plunge south into the Great Plains, eventually reaching West Texas by Friday morning (LT), October 23.
This winter storm system will also contain heavy rainfall. Showers and thunderstorms are expected to pass over the Midwest and northern Great Lakes today with the heaviest rainfall amounts expected to occur on Thursday.
There are Marginal risks for both severe weather and excessive rainfall on Thursday: the former centered in the heart of the Midwest and the latter positioned over the northern Great Lakes.
Featured image credit: NWS Great Falls
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