National Weather Service United States Department of Commerce

Overview

A powerful winter storm impacted a large part of southeast WY and the western NE Panhandle from Feb 22-24, 2017.  The storm originated over eastern Siberia around Feb 15, and then intensified in the following days as it tracked across the Gulf of Alaska.  The computer forecast models available to forecasters at the time were in remarkable agreement showing this storm impacting parts of the Central Rockies the following week, but failed to lock on to a solution with the track of the storm which would play a key role in the significance of the storm of the local area.  This is not uncommon, as limited data over the Pacific Ocean does not allow storms to be adequately sampled until they come on shore. This system came on shore on Feb 21st, and tracked across WY and CO on Feb 22nd and 23rd along with the passage of an arctic cold front.  This storm continued to pose challenges to forecasters, even 12-24 hours prior to the onset of snow. The track of the low pressure system was still uncertain due to blocking due to a strong area of high pressure to the north and east, and environmental conditions were favorable for enhanced precipitation rates due to instability in the atmosphere comparable to spring time thunderstorms.  The exact location of this area of instability would determine areas which would see the heaviest snow.  There were also concerns with dry air wrapping into the system and limiting precipitation amounts along the I-80 corridor. Finally, it was obvious to forecasters that snow amounts would be lower in Laramie, WY, due to easterly downslope winds causing drying on the west side of the Laramie Range, but it was not clear to what extent as models were still showing snowfall amounts in excess of 8 inches.

The storm brought an abrupt end to record breaking warmth, along with heavy snow and gusty winds for many areas. The days preceding the storm were warm and dry, characterized by temperatures in the 60s and even low 70s. As the cold front passed, high temperatures at Alliance, NE, fell from 73 degrees on Feb 21st to 34 degrees on Feb 23rd.  The snow began for areas west of the Laramie Range in south central Wyoming on the afternoon of Feb 22nd and spread into areas east of I-25 early in the morning on Feb 23rd, becoming very heavy at times on the 23rd with snowfall rates in excess of 2 inches per hour reported before diminishing in the evening and overnight into the 24th.  A broad swath of 12+ inches of snow was reported, including a narrow band (approximately 20 miles wide) of 20-25 inches extending from near Wheatland, WY, eastward through Torrington, WY, and Alliance, NE.  The dry air portrayed by the models caused a sharp cutoff in snow amounts to the south, with only 2-5 inches along the I-80 corridor from east of Cheyenne, WY, to Sidney, NE.  Only 1-3 inches of snow fell in and around the town of Laramie, WY.  In addition to the snow, gusty winds resulted in blowing and drifting snow especially across parts of western Carbon County, WY, where blizzard conditions occurred around Muddy Gap.  This storm resulted in major impacts to transportation, resulting in numerous road closures and no travel advisories across a large part of the region.

Radar Snow gif

Radar loop from Feb. 22 at 7:00 PM to Feb. 23rd at 1:00 PM, showing snow sitting over southeast Wyoming and western Nebraska.

Storm Timeline Weather Story before the Storm

The preliminary timeline for the winter storm from the

National Weather Service in Cheyenne

 

Feb 23, National Weather Service

Weather Story Graphic

Snow Reports:

Snow reports Map Snow Reports Table

 


Photos & Video:

Rolling Hills Snowfall measurements Torrington, WY

Snowfall in Rolling Hills, WY

Credit: Amy Potter

Snowfall meaurement in Lingle, WY

Credit: Cory Gilchriest

Snowfall in Torrington, WY

Credit: Eddie Juve

Douglas, WY Glendo, WY Goshen County

Snowfall in Douglas, WY

Credit: Roseanne Vasquez

Snowfall in Glendo, WY

Credit: Travis Gruwell

Snowfall in Goshen County

Credit: Unknown