Looking Ahead to Next Week's Storm: Is It the Real Deal? - NBC Boston

Looking Ahead to Next Week's Storm: Is It the Real Deal?

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    NEWSLETTERS

    Friday night: Snow showers taper off after midnight. Bitter cold starts to settle in and expect roads to be slick. Lows dip into the teens. Saturday: Peeks of sunshine, but dangerously cold with highs near record cold territory. High temps near 20 with wind chills near 0 at times. Sunday: More sun than clouds with highs into the mid to upper 20s.

    (Published Saturday, March 11, 2017)

    There's already buzz about the storm showing up in our 10-day forecast for next Monday night through Wednesday.

    One thing you know I cherish with our team at NBC Boston and necn is avoiding hype and sensationalism and delivering reliable facts... or at least reliable guidance that we hope is as close to the end result as you'll find. So, what's the deal on Tuesday and Wednesday? Hype or real?

    Let's start with the probability of a storm occurring at all: it's very high. Those of you who follow our NBC Boston and necn forecasts closely know that I spent two years with colleague Aaron Perry formulating our exclusive, in-house computer guidance to provide us with 10-days of critical weather information.

    Though our team is not bound to the output from our guidance, certainly we take it very seriously since we've home-grown the technology to feed it. The NBCU (NBCUniversal) Forecast System is showing a 90 percent chance of precipitation on Tuesday - four full days from today. That's huge. We tend to really sit up and take notice when the probability that far out rises to 50 percent, so to be so high is a sure sign to us that all the pieces are there for a sizable storm.

    Cary J Casse

    Next item: what is most certain about the storm? Wind. There is excellent agreement that the wind will significantly exceed normal thresholds Tuesday (less so, Wednesday), though wind direction still is dependent upon storm track.

    A track into New England would mean an east wind becomes southeast, then northwest. A track offshore means a northeast wind becomes north, then northwest.  

    Either way, utility companies and customers should be aware there is an increased risk for power outages Tuesday. Winds of this magnitude raise two more flags: coastal flooding potential and, if enough snow, blizzard conditions.

    Coastal flood parameters aren't exceptional given the height of the tide with relation to the moon, but while the tide may not be so high as a base level, it's high enough that if the winds really crank, an early afternoon tide on Tuesday and again overnight Tuesday night surely could produce some coastal flooding. The potential for blizzard conditions hinges upon rain or snow.

    Final item: Snow or rain? The likely answer to this is: both. The bigger question is how much of each. With arctic air from the weekend lingering through Monday and precipitation slated to arrive Monday night into Tuesday morning, this surely suggests at least a burst of snow will occur at the onset of the storm. How long snow lasts before changing to rain - if at all - is entirely dependent upon both the storm track and rate of intensification.

    A storm track up the coast and into Eastern New England or scraping along the coast will mean a propensity for an east and east-southeast wind to develop, carrying relative warmth off the 40 degree ocean waters and promoting a change to rain at the coastline. If the storm moves a bit farther east, I mentioned above that this promotes a more northerly wind, which would help to hold antecedent cold in place and produce more snow.

    The reality may lay in the middle - a coastal front that stalls inland over eastern New England, making for inland snow and a change to coastal rain. But again, it's too early to say. As we close in on the event, the texture of storm development and forecast temperature profile will become clearer.