By Meteorologist Joe Martucci
By the time you read this Feb. 13 edition of Shore Local magazine, you will have lived through four separate storm systems since Feb. 4.
The Feb. 4-5 snow event deposited a few tenths of an inch of snow in our area, which turned into a coating of ice, and then to plain rain for a while. Still, it was a low-pressure system that moved through the area.
Feb. 8-9 was the stronger sibling of the Feb. 4-5 snowfall. There was more snow and more ice, capped off with some rain. It was a slippery mess for a few hours. However we didn’t see the brunt of the wintry weather, unlike our friends in the western and northern parts of the state.
The storm Tuesday into Wednesday (which as of this writing had not occurred yet), should end up being New Jersey’s biggest, widespread snow of the winter with snow accumulation expected. Then another storm system is anticipated to impact us right after that.
Colder than average
While temperatures sit roughly 2 degrees below average for the South Jersey shore, according to the Southeast Regional Climate Center, there hasn’t been much winter weather to capitalize on these colder temperatures. However, an unusual weather pattern should at least give us the opportunity to close winter with a snowy bang for snow lovers.
Let’s talk about the usual weather patterns that can bring us cold and snowy weather. That is:
1) A stretching of the polar vortex into the Northeast this week
2) A favorable Arctic Oscillation
3) A so-so North Atlantic Oscillation
The polar vortex – the cold dome of low pressure that typically sits over the North Pole in the stratosphere – stretched down into the Northeast this week. This is the ninth time the polar vortex stretched this winter, according to Judah Cohen, Director of Seasonal Forecasting for Atmospheric and Environmental Research, Inc., in Massachusetts, and who was featured in our Winter Outlook during November.
That leads to a chain reaction which typically results in bitter cold and potentially snowstorms 10-14 days later. That would generally mean the weekend of Feb. 22 until the very beginning of March.
Big snow?
However, the Arctic Oscillation (AO) shows a favorable pattern for colder-than-usual temperatures and perhaps big snow as early as next week. The AO is in a negative state and should stay that way through next week, according to the Global Forecast System computer model, an American system.
When it’s negative, that leads to a wavier jet stream, the river of air about 30,000 feet high which separates colder and warmer air masses. The jet stream should dip into the Southeast, putting us on the more frigid side of the pattern.
The North Atlantic Oscillation (NAO) should stay in a neutral state for next week. So, it won’t influence us much. However, it’s an extremely popular index to look at in the weather world. When it’s negative, it will also send the jet stream to the southern United States, putting New Jersey on the colder, and perhaps snowier side. That negative state is possible at the end of the month.
To summarize, the negative Arctic Oscillation should bring at least some colder-than-average temperatures, and perhaps plowable snow. However, the last week of February has a strong signal toward frigid temperatures and our best threat of a big snowstorm this winter.
Now comes the unusual part. When the Arctic Oscillation is so negative like it will be next week, you usually see the cold air diving in from the north. That won’t be the case next week. Rather, the air cold enough for snow will be moving in a west-to-east direction. In the weather world, we call this zonal flow. New Jersey should stay on the chillier side of this throughout next week.
To be honest, this makes forecasting snow a bit easier for me. The rain/snow line won’t cut north to south near the New Jersey Turnpike. There isn’t much mixing, either. If you’re below freezing, you will see snow the whole time. If you’re above freezing, you will have rain.
Eventually, by the weekend of Feb. 22, we’ll get back into that familiar, wavy, north-to-south pattern from which we typically get our big snowstorms. That will last until the end of the month.
This is the South Jersey shore. Plowable snow isn’t guaranteed each winter. However, as our winter forecast said in November, the second half of February has as good of a chance as ever to do it.
