ROANOKE, Va. – Some of us got a little tease of snow early on Groundhog Day. Other than that, let’s not pull any punches. This winter has been pathetic from a snow perspective.
Most of the area falls six inches to one foot below normal on snowfall through February 7.
There’s hardly any sign that will change in the next two weeks at least.
For that, we look toward two large-scale weather patterns - the North Atlantic Oscillation (NAO) and the Pacific North American pattern (PNA).
North Atlantic Oscillation
The NAO takes into account two main features - 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 colder air to spill southward into the Eastern U.S.
In a positive phase, the opposite happens. The wind in the North Atlantic remains stronger, essentially hugging the cold air and keeping it north.
That’s what is currently modeled to (mostly) continue through 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 trough (dip) or a ridge (rise) in the Western U.S. air pattern.
Just like the NAO, there are two phases to the PNA.
1) Positive: A ridge of high pressure in the Western U.S. would imply a positive phase of the PNA, and it would be more likely to send colder air into the Eastern U.S. The reason for that is clockwise wind surrounding the ridge.
2) Negative: A trough of low pressure in the Western U.S. would imply a negative phase of the PNA, and it would be more likely to send warmer air into the Eastern U.S. The reason for that is counter-clockwise wind surrounding the trough.
That negative phase is what’s currently modeled to continue through at least the next two weeks (through February 22, 2023).
We will see a brief cold snap the weekend of the 11th and 12th. A slow-moving storm nearby may be enough to generate some mountain snow late Saturday into early Sunday. Outside of that, it’s unlikely that this becomes “the big one.”
Outside of that, we’re tracking another warming trend.
The Climate Prediction Center’s 8 to 14 day outlook shows the likelihood of warmer-than-average weather through Valentine’s Day and into the third week of February. Precipitation trends go up, but this will likely be in the form of rain during that time frame.
Snow-lovers would like to hold out some hope, but the window of opportunity is slowly shutting.
We can and do see accumulating snow in late February and March, but the percentages aren’t in our favor.
We’ll see if anything can shift in the global pattern after mid-to-late February. If not, this winter will have been one giant swing-and-miss.