The National Weather Service Office in Cheyenne has issued the following weather statement for Wednesday morning:

Pacific low-pressure system appears on track to impact most of southeast Wyoming and western Nebraska starting late today and this evening for locations west of Interstate 25; and further east along and east of I-25 tonight.

Winter Storm Watches were issued yesterday for all areas in the lower elevations of southeast Wyoming and all of western Nebraska (see attached graphic below).  Last night, we upgraded the mountains to a warning, but forecast snow amounts for the lower elevations remain uncertain so we will keep the Winter Storm Watch going this morning  This is because some of our forecast guidance shows a dry air layer aloft which may impede steady accumulating snowfall.  This is especially true along Interstate 80.

(Heaviest Snow) Location Confidence: Moderate confidence.  This has been the biggest headache with this storm.  Determining where and how widespread the heaviest snow will occur.  To add a little more detail to this, we are most confident (Moderate to High) for locations northwest of a Laramie to Alliance line.  Low to Moderate confidence for locations south of a Laramie to Alliance line (including Interstate 80 from Laramie to Sidney).  There is a very high spread of potential snow amounts due to some dry air aloft along Interstate 80.

Timing: High confidence with the timing of the onset of the snow

  • This afternoon and this evening for areas west of Interstate 25, likely impacting the evening rush hour.
  •  Tonight for areas along and east of Interstate 25. Most areas will see moderate snow for the Thursday morning commute.

However, there is only low to moderate confidence when the snow will end and when this storm will move out.  Some of our guidance shows the snow lingering well into Friday.

Snow Accumulations: Moderate confidence. 

There will be some wind with this storm once the wind shifts into the east on Thursday.  East to northeast winds sustained between 15 to 25 MPH with gusts up to 35 MPH  expected, mainly along and east of Interstate 25.  Drifting snow will likely occur over roadways with some patchy blowing snow at times greatly reducing visibility.

Stay tuned for additional updates today.  We will likely upgrade to Winter Storm Warnings for areas north of Interstate 80 shortly.