A deep upper-level low over central Canada is bringing the coldest air mass thus far this season down from western Canada into the northern Rockies and into the northern Plains, U.S.
This surge of arctic air is poised to bring heavy snow for the Rockies together with widespread record cold temperatures into much of the interior western U.S., even into the central and southern Plains during the next few days.
Temperatures in Peter Sinks, Utah (elevation 2 400 m / 8 000 feet a.s.l.) dropped to -37.1 °C (-34.7 °F) on October 28, 2019, setting a new national cold record for the month of October. This area is known for its cold winters, with the lowest temperature on record -56 °C (-69 °F) registered on February 1, 1985.
Widespread snow developed across Northeast and north-central Colorado Tuesday morning, October 29, delaying more than 250 flights and canceling 350 at Denver International Airport.
"Due to very cold temperatures, roads will become icy and snow-packed, with hazardous travel conditions, later this morning through tonight. Expect a difficult evening commute along the I-25 and I-70 Corridors and again Wednesday morning," NWS meteorologists warned.
Steadier light snow will continue overnight as well with some moderate snow this evening. Total accumulations will range from 20 - 40 cm (8 to 16 inches) in the mountains and foothills with 15 - 30 cm (6 to 12 inches) over portions of the adjacent plains. Mountain valleys will see 10 - 20 cm (4 to 8 inches).
"The cold air is being funneled southward from Canada into the western and central United States by a southward plunge of the jet stream," TWC meteorologists said. "That dip in the jet stream will slowly migrate eastward late in the week, taking the colder air with it. Not only will it be cold, but accumulating snow is expected from the Rockies to the Plains and upper Midwest."
Another look at the fresh snowfall in Iowa and Wisconsin via Terra #MODIS with false color providing a clearer distinction between clouds and snow where ice (including high clouds) and the new snow cover are shaded cyan. #IAwx #WIwx pic.twitter.com/NEltEPQImZ— UW-Madison CIMSS (@UWCIMSS) October 29, 2019
Temperatures are forecast to be 14 - 25 °C (25 to 45 °F) below average, with actual readings dipping below zero at the coldest locations over the northern and central Rockies.
The winds will also pick up as the heavy snowfalls, and they could be enhanced by local terrain as an expansive high pressure system builds in from the north. Blowing snow along with wind chills as low as -31.6 °C (-25 °F) below zero could be experienced in these areas. By Wednesday evening, much of the snow should be exiting the central Rockies and moving into the central Plains.
The snow should then reach the upper Midwest Wednesday night where up to 15 cm (6 inches) could accumulate by Thursday morning, October 31. This is in response to the development of a low pressure system over the southern Plains as it moves rapid toward the Mid-Mississippi Valley Wednesday evening and into the Appalachians Wednesday night.
Featured image credit: GFS, TropicalTidbits