A potent early season winter storm moved into Wyoming early on Thursday, October 3, and continued through much of Friday, October 4. Snow began in the higher elevations of western Wyoming early Thursday morning. Rain across the lower elevations changed to snow during the afternoon and evening hours of Thursday as colder air moved across Wyoming from west to east. With impressive upper level dynamics and ample moisture, snowfall rates approached two inches an hour at some locations.
The wet, heavy snow fell on trees that still had full foliage and brought many limbs and trees down onto streets and power lines. Natrona County was hardest hit with 14,000 customers without power at the peak of the storm. Several warming shelters were established Friday along the I-25 corridor to help those without heat. The heavy snow also brought many road closures to central Wyoming. In Casper, snowfall of 16.2 inches was the tenth highest storm total since records began in 1937 and held a liquid water content of 2.14 inches. The highest snowfall amounts fell in the higher elevations with over two feet of snow recorded in the higher elevations of the Wind River, Bighorn, and Absaroka ranges, as well as Casper Mountain. The highest amount was at the Reno Hill SNOTEL where 34 inches of snow was recorded. Many lower elevation locations east of the Continental Divide reported 6 to 12 inches of snow.

Winter Storm in EAST SWEETWATER COUNTY, WYOMING
From 03-OCT-13 09:00:00 to 04-OCT-13 21:00:00 (MST-7)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Trained spotters reported 10 to 12 inches of snow in Wamsutter.

Winter Storm in ABSAROKA MOUNTAINS, WYOMING
From 03-OCT-13 04:00:00 to 04-OCT-13 15:00:00 (MST-7)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: SNOTEL

Several SNOTEL sites in the Absaroka mountains reported heavy snowfall. Some totals include 27 inches at Marquette, 26 inches at Blackwater and 24 inches at Evening Star.

Winter Storm in CODY FOOTHILLS, WYOMING
From 03-OCT-13 12:00:00 to 04-OCT-13 09:00:00 (MST-7)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

A trained spotter reported 6 inches of snow in Cody.

Winter Storm in SOUTHWEST BIG HORN BASIN, WYOMING
From 03-OCT-13 15:00:00 to 04-OCT-13 15:00:00 (MST-7)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

A trained spotter reported 7 inches of snow in Thermopolis.

Winter Storm in OWL CREEK & BRIDGER MOUNTAINS, WYOMING
From 03-OCT-13 06:00:00 to 04-OCT-13 15:00:00 (MST-7)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: SNOTEL

The Owl Creek SNOTEL station reported 12 inches of snowfall.

Winter Storm in WIND RIVER BASIN, WYOMING
From 03-OCT-13 15:00:00 to 04-OCT-13 18:00:00 (MST-7)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Official NWS Observations

A winter storm brought 7 inches of snow was measured at the National Weather Service office in Riverton. Total snowfall ranged from 5 inches in Pavillion to 9 inches 12 miles northeast of Lysite.

Winter Storm in NORTHEAST JOHNSON COUNTY, WYOMING
From 03-OCT-13 17:00:00 to 04-OCT-13 18:00:00 (MST-7)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Social Media

A report of 6 inches of snow in Buffalo was received on Facebook.

Winter Storm in SOUTHEAST JOHNSON COUNTY, WYOMING
From 03-OCT-13 20:00:00 to 04-OCT-13 18:00:00 (MST-7)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Department of Highways

Interstate 25 was shut down in southern Johnson county due to strong wind and blowing snow.

Winter Storm in WIND RIVER MOUNTAINS EAST, WYOMING
From 03-OCT-13 10:00:00 to 04-OCT-13 18:00:00 (MST-7)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: SNOTEL

Reports of 15 to 24 inches of snow were received from several SNOTEL stations; including 24 inches at the Little Warm SNOTEL.

Winter Storm in LANDER FOOTHILLS, WYOMING
From 03-OCT-13 16:00:00 to 04-OCT-13 17:30:00 (MST-7)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Official NWS Observations

Snowfall amounts ranged from 10 to 16 inches across the Lander Foothills.

Winter Storm in GREEN MOUNTAINS & RATTLESNAKE RANGE, WYOMING
From 03-OCT-13 12:00:00 to 04-OCT-13 21:00:00 (MST-7)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Broadcast Media

A local television meteorologist relayed a report of 12 inches of snow near Garfield Peak. In addition, a trained spotter reported 8 inches of snow in Jeffrey City.

Winter Storm in CASPER MOUNTAIN, WYOMING
From 03-OCT-13 15:30:00 to 04-OCT-13 23:00:00 (MST-7)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Spotters reported 24 to 30 inches of snow on Casper Mountain.

Winter Storm in UPPER WIND RIVER BASIN, WYOMING
From 03-OCT-13 15:30:00 to 04-OCT-13 05:00:00 (MST-7)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Trained spotters reported 12 to 14 inches of snow in and around Dubois.  Up to 8 inches of snow was measured in Crowheart.

Winter Storm in BIGHORN MOUNTAINS SOUTHEAST, WYOMING
From 03-OCT-13 09:00:00 to 04-OCT-13 19:00:00 (MST-7)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: SNOTEL

Many SNOTEL stations estimated  heavy snowfall. Some amounts include 31 inches at Little Goose, 26 inches at Cloud Peak and 21 inches at Hansen Sawmill.

Winter Storm in BIGHORN MOUNTAINS WEST, WYOMING
From 03-OCT-13 09:00:00 to 04-OCT-13 19:00:00 (MST-7)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: SNOTEL

Very heavy snow fell at SNOTEL stations in the western Bighorn Mountains. Some of these included 27 inches at Middle Powder, 18 inches at Shell Creek and 17 inches at Powder River Pass.

Winter Storm in ROCK SPRINGS & GREEN RIVER, WYOMING
From 03-OCT-13 09:30:00 to 04-OCT-13 20:45:00 (MST-7)
Property damage: 0.00K
Crop damage: 0.00K
Reported by: Trained Spotter

Trained spotters reported up to 8 inches of snow in Rock Springs and 4 inches in Green River.

Winter Storm in NATRONA COUNTY LOWER ELEVATIONS, WYOMING
From 03-OCT-13 18:30:00 to 04-OCT-13 23:00:00 (MST-7)
Property damage: 3.00M
Crop damage: 0.00K
Reported by: Trained Spotter

Most areas of Natrona County received over a foot of snow including 16.2 inches at the Casper Airport and up to 22 inches in the foothill areas of Casper Mountain. The heavy, wet snow fell on trees that still had full foliage and caused branches and in some cases whole trees to fall. Many of these landed on power lines and caused widespread power outages. Around 14,000 customers were without power at the peak of the storm.