Arctic air clash could trigger a major snowstorm for New England. Here’s the latest from Dave Epstein.
"Since it’s only Wednesday and any impact is four or more days away, there’s still plenty of time to modify the forecast."
Obviously, people are already talking about the possibility of more snow across New England this weekend. First, let me give you a little meteorology. One of the key principles of the atmosphere is that cold air is heavier and denser than warm air. When these two air masses meet, the warm air lifts, creating condensation, clouds — and snow and rain.
Why do I mention this? Over the next several days, we’re going to see a renewed mass of cold Arctic air descend into the United States, sending temperatures below their 30-year averages from Texas to Northern Florida and north to our area.
This bitter cold, heavy air and the boundary between the warmer air to the south is going to act as a catalyst for a swath of snow and rain that will ride from the Mississippi Valley to the Ohio Valley and then off the Mid-Atlantic coast.
The southern and northern extent of the snow shield is still in question, and this plays into our forecast for the upcoming weekend. There’s no doubt that there’s going to be a significant amount of snow for parts of the eastern U.S. that have not seen much snow, not only this winter but over the past several years.
But an important aspect when looking at the intensity of this storm for New England: Is this system the type of storm in which the precipitation is strung out in an east-west fashion, or does it become more concentrated within a stronger, low-pressure system?
Once the storm exits somewhere along the Mid-Atlantic coastline, it will have to fight the cold, dense Arctic air that will overtake New England starting Friday night. I’ve seen situations where enough of the cold air relaxes to pull in the precipitation and that’s where we get those storms with very light fluffy snow.
Snow or ice and a wintry mix?
Another aspect to our upcoming chance of snow: It’s unlikely that we will see anything but snow. It will just be too cold. You may have heard sometimes that it’s too cold to snow, but that’s not the case. It’s just that we tend to need a little less cold air after a very cold outbreak to get snow.
If the moisture can erode enough of the cold air to move northward along the jet stream, then we will be looking at accumulating snow most likely Sunday night into early Monday.
If the jet stream is farther south, then the precipitation will remain along the thermal boundary, and although we could see some snow, it would not become a major weather system.
Right now, I think this could go either way, and the forecast models that we use are likely to oscillate between us seeing a good amount of snow and keeping it farther south.
Since it’s only Wednesday and any impact is four or more days away, there’s still plenty of time to modify the forecast. I know this can be frustrating, but this is the nature of long-range forecasting. The best information right now is that we have potential for a storm late in the weekend. I am comfortable with this.
If you had travel plans late this weekend and early next week, especially to the Mid-Atlantic, I might consider moving them because even if we don’t see the snow here, it’s more likely to impact travel from New York City to Washington, D.C., and will definitely ripple through other airports.
Obviously, I can’t tell you the exact impact at this point, but I would say that’s the biggest risk as of now.
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