RICHMOND, Va. (WRIC) – Winter is on the way, and it is time to find out what you can expect here in Central Virginia. For those who love lots of snow and days off from school, I’ll be honest with you – you are probably going to be disappointed in what you see this year.
In many ways, this winter’s weather pattern is going to resemble what we had last year. Hopefully, we get to February we won’t experience back-to-back ice storms.
First up, and most important in the forecast, is that this year will again feature a La Nina pattern in the Pacific Ocean. That is a setup where the water temperatures off the coast of Peru will be colder than normal. One item of note — the La Nina this year appears to be weaker than what we saw last year and could start warming towards an El Nino by the end of winter/start of spring.
What happens in a La Nina year is that the southern jet stream is somewhat weaker, and the northern or polar branch of the jet is strong and more dominant. Who gets exactly what depends on how the jet aligns, but in general here is the pattern you can expect.
The southern tier of the nation stays warmer and drier than usual. That extends right up into the Mid-Atlantic area. Wet weather affects the Pacific Northwest and the Great Lakes. The coldest weather is generally found over the Rockies and the Northern Plains.
La Nina and El Nino are not the sole factors that affect the winter weather patterns. There is the North Atlantic Oscillation, which affects the patterns found in the Atlantic Ocean. There is also the Polar Vortex, which we will touch more on in just a little bit.
But first, let’s talk about what we typically see for temperatures and snowfall during El Nino, Neutral (La Nada), and La Nina years. These graphics are courtesy of Larry Brown at the Wakefield NWS office.
Note the yellow line that you will see is what happened last year.
El Nino tends to have the coolest weather in the area and in a La Nina year, we average about 1.3 degrees warmer. (If you compare Median temperatures the difference is 2.2 degrees). Now those numbers may not sound like much, but they make a very large difference in your heating bills.
Looking at snowfall, the numbers tend to be in reverse order with more snow in an El Nino year, and less in a La Nada year. But here in lies a problem for us. If you look at the charts, our highest individual winters have actually come in “neutral” years. 3 out of the top 4 to be exact. And the La Nina year of 1995-1996 was a top 10 year.
What this means is that in a La Nina year it is more of a case of fewer opportunities to have snowfall in our area. But that does not rule out getting a “big storm” that drops lots of snow.
Now, to what in many ways is the wildcard in the winter. That’s the Polar Vortex, which is a fast-moving river of air that circulates clockwise near the Arctic Circle. But here is the key. There actually are two of them. One in the troposphere, and one in the stratosphere. And what happens high up in the stratosphere can have huge effects on us here on the ground. Where the air pressure is 1/1000th of what we see on the ground, we have observed abrupt and sudden warming of the air.
And this throws the vortex in the stratosphere into chaos. It slows down and has been seen to reverse direction at times. About two to three weeks after this happens, it results in cold air cascading downwards through the atmosphere into the troposphere. One of the results of this is that the circulation can stretch and dip southward. This also leads to very significant outbreaks of arctic air into the U.S. and Europe.
This happened last year and resulted in the massive cold blast that affected Texas, and contributed to the two ice storms that we saw.
So, with that in mind, here is how I see our winter playing out over the area.
I am looking for a chilly start to December that could also feature an early-season winter storm for parts of the area.
After that, we warm into January – the “thaw” will be real, and I would not be surprised at all to see the temperatures zoom above 70 degrees.
In February, the weather turns stormy. A “Polar Vortex” outbreak could yield to ice and snow, and a big warm-up could lead to an early start for severe weather season.
When you put it all together, I expect that we will see:
- Temperatures 1.4 degrees above normal
- Snowfall of 8.4”, which is below normal —t hat’s barring a “blockbuster” type storm. I also see an ice storm potential at some time in the winter.
- Finally, our chance for a White Christmas is a mere 6%.
We will see what happens LATEST FORECAST