Blizzard of 2015 – Sunday Update

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It’s a beauty from a meteorologist’s perspective and a beast from a normal person’s perspective. The Blizzard of 2015 will be quite a storm across the region. A couple questions I want to answer right off the bat which have come up today.

  • 15″-30″ – why such a big range?
    • Most of us will get somewhere between 15″ and 20″ of snow from this storm. That said, there will likely be a band of heavier snow of between 20″ and 30″. At this point there is very little skill in trying to figure out where in the state that band will be. When we have a better idea we’ll indicate it on the snowfall map. Additionally, there’s not a tremendous amount of difference in how you should prepare for 18″ of snow and how you should prepare for 30″.
  • Where the hell did this storm come from? You said it wouldn’t be a big deal on Thursday!
    • Yup, things changed in a big way. This is one of the few storms in recent memory that wasn’t well modeled beyond 96 hours. The European model on Friday night that came out indicating the potential for a major snowstorm lead the way and by midday Saturday all of our computer models were on board. It’s a testament to how far computer modeling and weather forecasting has come in the last decade – when I started looking at weather models and forecasting in the mid 90s seeing a storm appears out of nowhere 48 hours out was a regular occurrence! That almost never happens in 2015.
  • Will this storm be as bad as the Blizzard of 2013?
    • Maybe, but probably not. The February 2013 blizzard was a 2 or 3 time a century kind of storm. The heaviest band of snow set up in the most populated part of Connecticut (Bridgeport/New Haven/Hartford) which made the storms impact seem that much worse! While some places could conceivably see 30″ of snow – the odds of Bridgeport, New Haven, and Hartford getting there from the same storm are quite low.
  • You’re giving this storm a 9 out of 10 on your impact scale, why not a 10?
    • 2 reasons. 1978 and 1888.
  • The National Weather Service is predicting 24″-36″ for us how come you guys are so much lower?
    • We’ve seen that forecast and while it certainly may verify in some areas we expect those kinds of totals to be much more localized then they’re showing. 24.0″ is also the record for biggest snowstorm at BDL and 20.0″ is the second biggest snowstorm on record for Bridgeport. Setting 24″ as the lowest bound for a snowfall forecast in this area is a very, very, very tough bar to reach.

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The track of this storm is a classic and that’s why we’re thinking it will be a blockbuster. Many of our biggest storms have featured a subtle, but detectable, counter clockwise loop just southeast of Connecticut as they deepen and stall. This one is modeled to do that.

One of the features that I find most useful in forecasting where the heaviest band of snow will set up is tracking where the low pressure systems above our heads at 850mb and 700mb track (that’s between 4,000ft and 9500ft up or so). To the northwest of these lows that’s where the heaviest snow will set up due to a process known as frontogenesis. This produces a narrow band of intense lift that slopes toward the cold air with height.

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It’s important to get those lows close to, but not west of, Montauk Point to ensure the heaviest banding sets up over Connecticut. Near and east of the mid level low track there are all sorts of issues that develop including the dreaded “dry slot” that is almost as painful for snow geeks as the sound of sleet pinging on your window.

As the storm wraps up winds will pick up as well. The combination of heavy snow and strong winds has lead to the issuance of a Blizzard Warning. While blizzard criteria is exceedingly difficult to reach (sustained winds >35 mph and visibility <1/4 mile) we should get close. Our computer models also show the potential for damaging wind gusts – possibly over 60 mph.

B8O6Ap5CQAAoJ1qThe GFS model is not quite as robust as the European with wind speeds but it still is indicating the potential for 60 or 65 mph wind gusts in southeastern Connecticut especially.

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In this profile you can see a wind speed of 66 knots about 2,000 feet above the ground – and a profile that’s favorable for a good portion of this to mix down to the ground. We’ll have to see how this develops through the night and into tomorrow. Power outages are certainly a possibility.

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Hopefully you’ll be able to hunker down and enjoy the storm. We’ll have you covered on NBC and of course on Facebook, Twitter, and basically everywhere.

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3 thoughts on “Blizzard of 2015 – Sunday Update

  1. Thanks for providing the most reasonable, least OMG-we’re-gonna-die forecast. You rock. Just one question based on your opening sentence … are you suggesting meteorologists are not normal?
    Best,
    Jason’s Mom

  2. Thanks Ryan. Very informative. Personally, I’m praying for the “dry slot.” Right over my house would be a great spot for it. I’ll gladly send my bands of snow to your house. 🙂

  3. Pingback: West Hartford Prepares for Possible Blizzard - We-Ha | West Hartford News

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