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Winter Storm Watch in effect, record lows forecast as cold front arrives Monday

CASPER, Wyo — An “unseasonably strong storm system for September” is coming from the north and is expected to hit the Montana-Wyoming border Monday morning, prompting a Winter Storm Watch for many area across the western and central region, according to the National Weather Service (NWS) Riverton.

By Tuesday record lows for the date are forecast in some places, including Casper with a low of 28.

National Weather Service (NWS) Riverton.

The advisories take effect from Monday afternoon into the evening (as the front moves south)  until noon on Tuesday. Precipitation will begin over the north Monday afternoon spreading south into central Wyoming Monday evening, NWS said. At lower elevations the precipitation is expected to begin as rain before changing to snow

Natrona County could see 3 to 6 inches of total snow accumulation and 6 to 12 inches on Casper Mountain, with wind gusts as high as 45 mph.

Riverton, Shoshoni, Lander could see snow accumulations of

  • 3 and 6 inches in the Wind River Basin, 
  • 4 to 8 inches in the Lander Foothills, 
  • 12 to 18 inches on the eastern slopes of the Wind River Mountains.
National Weather Service (NWS) Riverton.

Rock Springs, Green River and Wamsutter could see 1 to 2 inches of accumulation with 60 mph wind gusts impacting travel.

Winter weather advisories take effect earlier for higher elevations, beginning at 9:00 a.m. Monday. These include Absaroka, Beartooth, northern Bighorn mountains, with accumulations 6 to 10 inches in these areas, and up to 5 inches in the Red Lodge and Beartooth foothills.

National Weather Service (NWS) Riverton.

Reduced visibility and freezing slush could impact travel, and power lines and tree limbs will be vulnerable to the weight of heavy snow, NWS said.

“Significant snowfall is possible for mountains east of the Divide and central Wyoming…. Very strong northerly wind will also accompany the cold front,” said NWS.

After a Labor Day weekend of record highs for September, temperatures are expected to plunge to below freezing many areas.