Cheyenne, Wyo. - Hello everyone! I hope you all had a great weekend as we were treated to sunny skies. As we move into a new week (November 13-20) we are tracking a chance for some snow on our Friday, and I want to break down the ingredients going into this storm.
To begin I’m sure many of you have noticed it has been pretty dry here across Southeast Wyoming over the past few weeks. While some of you may think that means we are in a drought, November just happens to be a dry month for Cheyenne as we only average about three quarters of an inch of precipitation for the month. This week it will be much of the same with exception of Friday where the chance of snow looms.
The current pattern we are in supports the idea of snow on Friday for a couple of reasons. First, the all-important Pacific/North American teleconnection (PNA) has been deeply negative, which suggests colder temperatures across the Western United States. Secondly, the Arctic Oscillation teleconnection (AO) has been neutral, but is expected to move into the negative this week, which means more Arctic air in the continental United States. So overall the pattern is somewhat geared towards wintry conditions in Wyoming.
(See photo titled Current PNA and forecast)
(See photo titled Typical Negative PNA pattern)
(See photo titled Current AO and forecast)
(See photo titled Typical AO pattern when negative)
So that brings us to this upcoming Friday. Right now we are expecting a quick moving area of low pressure to move onto the Pacific Northwest Thursday, and then track towards the southern plains later on Friday. It’s during the morning hours on Friday when the capital city could experience some snowfall. This wouldn’t a long lasting or particularly intense event outside of the mountains. Right now the best bet on amounts in southeast Wyoming would be 4 to 6 inches in the mountains, and about 1 or 2 inches in the lower elevations. Once the system leaves our area sunshine will return for weekend and temperatures should rebound to around 50, which is slightly above average. So were looking at a quick hit of winter again Friday and then returning to fall for the weekend.
(See photo titled Surface map for 11am Friday (Blue=Snow, Green=Rain))
(See photo tilted Potential Snowfall forecast for Friday)