Discussion On Tuesday's Winter Storm
- Jackson Dill
- Mar 11, 2017
- 3 min read
If you haven't heard yet, a major, blockbuster winter storm named Winter Storm Stella is likely for southwestern Connecticut and all of New England during the Tuesday into Wednesday period. In this article, I want to discuss with you the implications about the forecast of this nor'easter and give you sense about what I think will happen.
Discussion:
The two major weather models that I like to look at are the American (GFS) and European (EURO or ECMWF). What we know is that both of these models agree that there will be a strong storm moving up the East Coast. Because of how strong this storm will be, you know winds will be howling. Both the GFS and EURO models have winds gusts frequently exceeding the blizzard threshold of 35 mph winds. Therefore, a blizzard is very possible.
What we don't know, which is the main issue with this forecast, is the position of that low. The position of the center of the low pressure, or the center of the storm, ultimately determines what weather we will deal with. There's an origin southeast of the Northeast region in the Atlantic called the 40/70 benchmark. 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.
With this particular storm, the EURO model positions the center of the storm basically right over that 40/70 benchmark. This means heavy snow for much of the Northeast.
The EURO's 51 ensemble members, which are runs of the same model but with slightly different environmental conditions, show a spread between the low positions (tiny L's on map below) Tuesday. However, the mean location (light green shade on map below) is also directly over the benchmark. Also as of Saturday morning, that spread or disagreement among the ensembles is lessening and tightening up, showing more confidence in this forecast.
As of Saturday morning, the GFS model also has a similar approach to the placement of the low pressure system, but the previous model runs of the GFS had this storm moving inland, making it north and west of the benchmark. With the GFS, the confidence is lower because the track is still changing.
Currently, both the EURO and GFS models keep all of our area in the snow during the whole event despite the different positions being forecast.
The location of the center will determine how much snow we will receive. The GFS model shows about a foot and a half of snow, whereas the EURO is predicting even more at about two feet. There is very significant support for greater than half a foot (six inches) of snow. It's all but a certainty with a 90-99.9% chance.
There is also a good deal of support for greater than a foot of snow. The EURO is currently giving our area a 70-80% chance for that amount.
When we look at the ensemble members of the EURO again, only 2 out of the 51 members are forecasting less than six inches of snowfall for our area.
Looking at the GFS ensembles, they have a pretty similar idea with only 2 out of the 20 members predicting less than six inch of snowfall.
Therefore, the chances are pretty high for greater than one foot.
My 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!
The worst of this storm I think will occur during the Tuesday afternoon and evening time period. I know everyone wants to know about snowfall totals. I really believe everyone will pick up at least a foot of snow, especially inland. There is tremendous model support for greater than one foot. There is even the potential for two feet of snow, so as of now I'm forecasting one to two feet of snow accumulations. I'm actually leaning toward the two feet solution! As this event gets closer, we will know more about what will happen with the position of the center of the storm. Again, the center of this storm means the difference between rain and some snow, or greater than two feet of snow.
Stay with Jackson's Weather through Tuesday's winter storm for the latest information.
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