First Snow, First Frost As Fall Cold Front Plunges (FORECAST)

Linda Lam and Jon Erdman
Published: September 11,2014


 
Over a foot of snow was reported in parts of Wyoming Thursday as an unusually early snowstorm spread southeastward with 12 days of summer still remaining.
The season's first frost and freeze is also on the way for parts of the Rockies, Plains, Northwest, and Upper Midwest this week.

Summer Snow!

Thursday morning brought the earliest measurable snow on record to Rapid City, South Dakota.
Snow piled up to 8 inches deep in the Black Hills near Custer, South Dakota.
Farther west, the snow was even heavier in parts of northern Wyoming, where up to 14 inches fell near the town of Story in Sheridan County. Broken branches, downed trees and power outages resulted from the heavy, wet snow in that area.
Winter storm warnings and winter weather advisories have been allowed to expire for Montana, Wyoming, and South Dakota.
However, some lower elevation rain may change over to wet snow as far south as northeast Wyoming and the Nebraska Panhandle as the cold air marches south Thursday night, resulting in 1 to 3 inches of snowfall in a few spots. Scottsbluff, Nebraska could also see one of their earliest measurable snowfalls (record earliest: Sep. 11, 1974).
(FORECAST: Glacier National Park | Mount Rushmore | Rapid City)
Rain may even mix with snow in Denver on Thursday night.

A Legacy of Snow

Multiple rounds of snow were reported across a large part of Canada's Alberta province Monday through Wednesday, including its largest city, Calgary, as temperatures fell below freezing at times.
(PHOTOS: Calgary's Summer Snowfall)
Tuesday, a section of the Going-to-the-Sun Road in Glacier National Park over Logan Pass was closed by park officials due to snow.
Great Falls, Montana, witnessed its earliest first snow of the season in 22 years Tuesday night. Only six other years since 1892 featured snow before September 9 in Great Falls, according to the National Weather Service.

Tracking the Cold 

Frosty mornings are in the forecast again Friday and Saturday as this fall air invades the U.S. behind a strong cold front surging south from Canada.
In fact, temperatures well below freezing have already been recorded in parts of the northern Rockies. Daniel, Wyoming, recorded a low of 16 degrees Thursday morning, while Libby, Montana checked in at 27 for that state's Thursday morning low.
Casper, Wyoming, sank to 30 degrees at 6 p.m. Thursday, only the fifth time the city's reached 30 degrees or colder on or before Sept. 11 in 74 years of records.
Frost advisories and freeze warnings are in effect as far west as northeastern Washington, as some of the cold air manages to force its way through the mountains. The brunt of the chill, however, is as usual sliding southeastward down the eastern slopes of the Rockies and onto the Plains.
(MAP: Average First Freeze)
Record lows are possible Friday morning in parts of the northern Rockies and northern High Plains, including Sheridan, Wyoming, and Rapid City, South Dakota. By Saturday morning, that record cold may spread into the Plains and record lows are possible in Kansas City and Oklahoma City.
(FORECAST: Denver | Omaha)
It would be about two to three weeks early for temperatures to drop to 32 degrees or below in Billings, Montana (average date is Oct. 3), Bismarck, North Dakota (average date is Sept. 21) and Rapid City, South Dakota (average date is Sept. 27). Lows in all three cities should flirt with the freezing mark through late week.

Chilly High Temperatures, Too

The cold air started spilling over the international border from western Canada into northern Montana around Cut Bank back on Monday.
Daily record cool high temperatures were set in many locations including Cut Bank on Tuesday (39) and Wednesday (36) and in Rapid City, South Dakota (45) on Wednesday.
Chicago only reached 56 degrees Thursday, the earliest in the season they've had a high temperature that chilly since 1917.
Rapid City saw a high temperature of 90 degrees on Monday, but topped out at a frigid 39 degrees Thursday.
Colder temperatures continue to move south and east behind the cold front. High temperatures Friday may be as much as 40 degrees below mid-September averages in parts of the Oklahoma and Texas Panhandles.
High temperatures will struggle to get out of the 50s across the High Plains and Upper Midwest Friday. With clouds and rain, parts of the southern High Plains may stall in the 40s, including places such as Clayton, New Mexico, where average mid-September highs are still in the lower 80s.
(FORECAST: Bismarck | Kansas City | Chicago)
The below-average temperatures will advance even farther south and east this weekend.
Highs may climb only into the 70s for parts of the Tennessee and the Mid-South region heading into the weekend, bringing a welcome break from the heat and humidity.
There will even be some relief in the heart of Texas, where high temperatures will go from the 90s to the 70s and 80s.
(FORECAST: Little Rock | Nashville | Dallas)