Winter Storm Stella: Forecast and Discussion
- Jackson Dill
- Mar 12, 2017
- 4 min read
We are now less than 48 hours away from the main event, which is Winter Storm Stella. I want to begin by saying our area will be hit by this nor'easter and that significant snowfall is very likely. You want to prepare now for the snow as well as the wind because power outages are possible. Check out our article on how to prepare before a snowstorm on our home page.
Winter Weather Alerts:
The National Weather Service has gone ahead and issued a Blizzard Watch for the coast and a Winter Storm Watch for the interior locations. Both of these winter alerts are in effect from 12AM Tuesday through 12AM Wednesday.
It is very early for the National Weather Service to issue winter weather alerts like this so far in advance, but this means that highly impactful snow is likely and now is the time to prepare. In case you didn't know, a blizzard is defined as sustained winds or frequent gusts greater than 35 mph combined with visibilities less than a quarter of a mile, continuing for at least three consecutive hours. Blizzards are hard to verify, but this storm has the chance of bringing an official blizzard to at least the coast.
Forecast Discussion:
The major weather computer models as of Sunday morning have trended back to the west again with its track, especially the EURO. That means the storm will move closer to the coast and inside the 40/70 benchmark (see below), bringing rain to at least southeastern Massachusetts. I think our entire area of southwestern Connecticut will remain in the snow the entire time. In terms of the GFS model, it brings the center of the low pressure almost directly over the benchmark. Previously, both the GFS (American) and the EURO (European) models had the storm moving further east and outside of the benchmark than the further previous model runs. The models are still fluctuating, so we still can't focus on one track.
The 40/70 benchmark is an origin southeast of the Northeast region in the Atlantic. It gets its name because it's located at 40° North and 70° West. Whenever centers of storm systems move directly over this benchmark, the Northeast usually gets its biggest winter storms. If it moves north and west of this point, warmer air usually moves in, leading to rain at the coast. If it moves south and east of this point, most of the snow remains confined to the coast with inland locations remaining dry.
Again, I can't stress how important the track of the center of the low pressure is in terms of snowfall totals, which I know everyone wants to know about. The EURO's 51 ensemble members, which are runs of the same model but with slightly different environmental conditions, are beginning to agree on where this storm is going to go and it is likely to move inside of north and west of the 40/70 benchmark. If you look at all those tiny L's on the map below, you could see how they're all clusters just off the coast of New Jersey. With this scenario, which is looking more and more likely, we'll have to watch the rain/snow line very carefully at the coast. As of now, however, I still believe everyone will have an all snow event.
Based on what I think will be the track of the storm, which is basically what the EURO is showing us, you know winds will be very strong. The peak of the winds looks to be Tuesday evening where there is the potential for wind gusts all the way up to 50-60 mph. This may still change, but that's what it's looking like right now. Therefore, scattered power outages are expected and blizzard conditions could be expected.
Now in terms of snowfall totals, there is still only low to moderate confidence until the track of the low is set in stone. Until then, all I can talk about now are the chances for certain amounts of snow and I can give you a very general, broad range of what I'm thinking. The majority of the GFS ensemble members are focusing around that 10 and 14 inch range. This does not factor in higher snowfall ratios due to cold air, especially away from the coast where it will be in the upper 20's.
Now let's talk about the chances for certain amounts of snow according to the EURO ensembles:
There's about a 100% chance for greater than six inches of snow.
There's between a 70 and 90% chance for greater than one foot of snow.
There's up to a 10-20% chance for greater than 18 inches of snow.
Forecast:
Given all the details I gave above, this leads me to conclude that a major winter storm is likely from late Monday night through Tuesday night. Then snow showers will remain from the backside of the storm Wednesday. Tuesday will be the big day!
Now for snowfall totals, the heaviest of the snow will occur during the Tuesday
afternoon and evening time period. Once all is said and done by the end of Wednesday, I think 10 to 20 inches is the most likely scenario, but it really all depends on the track of the low, which will determine snowfall amounts and where the rain/snow line will set up.
Stay with Jackson's Weather through Tuesday's winter storm for the latest information.
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