ROANOKE, Virginia – Some of us got a little sneak peek of the snow early on Groundhog Day. Other than that, let’s not beat around the bush. This winter has been pathetic from a snow perspective.
Most of the area falls six inches to a foot below normal in snowfall through February 7.
There are almost no signs that it is going to change in the next two weeks at least.
For that, we look at two large-scale weather patterns: the North Atlantic Oscillation (NAO) and the North American Pacific (PNA) pattern.
North Atlantic Oscillation
The NAO takes two main features into account: low pressure around Iceland and high pressure around the Azores. The difference between air pressure generates wind. The greater the difference, the stronger the wind. The smaller the difference, the weaker the wind.
In the case of the NAO, there are two phases: 1) positive and 2) negative.
In a negative phase, the wind between the two features is weaker in the North Atlantic. This allows cooler air to spill south into the eastern US.
In a positive phase, the opposite happens. The wind in the North Atlantic continues to get stronger, essentially hugging the cold air and keeping it north.
That is what is currently modeled to (mostly) continue for at least the next two weeks (through February 22, 2023).
Pacific North American pattern
The PNA often refers to whether or not there is a valley (dip) or crest (rise) in the air pattern of the western US.
Like the NAO, the PNA has two phases.
1) Positive: A ridge of high pressure in the western US would imply a positive phase of the PNA, and would be more likely to send cooler air into the eastern US. The reason for this is wind clockwise around the crest.
2) Negative: A low pressure trough in the western US would imply a negative phase of the PNA, and would be more likely to send warmer air into the eastern US. The reason for this is wind counterclockwise surrounding the depression.
That negative phase is what is currently modeled to continue for at least the next two weeks (through February 22, 2023).
While we do see a brief cold snap around the weekend of the 11th and 12th, the only hope for snow accumulation will be mostly around the west-facing slopes near the West Virginia-Virginia border.
The 8- to 14-day outlook from the Weather Prediction Center shows the probability of warmer-than-average weather through Valentine’s Day and through the third week of February. Precipitation trends are increasing, but it is likely to be in the form of rain during that time period.
Snow lovers would like some hope, but the window of opportunity is slowly closing.
We can and do see snow accumulation in late February and March, but the percentages are not in our favor.
We’ll see if anything can change in the global pattern after mid to late February. If not, this winter will have been one big swing-and-miss.
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