As expected, light snow is already breaking out across parts of Greater Boston. The snow will continue to pick up in intensity today, with the peak of the storm after 8 PM. Roads will start to go down hill after 2 PM this afternoon, so make every effort to wrap up your business by then. Most places will pick up a widespread 1-2 feet of snow by Saturday afternoon, with a few isolated towns picking up even more than that.
The Set Up: A classic winter storm will take shape off of the Mid-Atlantic coast Thursday, gathering strength as it slides Northeast Friday and Saturday.
Friday- Pockets of light snow will begin as early as Friday morning as the storm advances, with a little bit of rain mixed in from Boston down through the South Shore, Cape, and Islands. As the day wears on expect the snow to become steadier and eventually heavier by the evening commute. Mixing will persist near the coast, but inland expect at least 1-3″ to be on the ground by dinner. If you are trying to fly out before the storm, your best chance of getting out is to depart before noon. On the roads, it would be best to be in by about 2 PM. While driving will be possible through the evening commute, things will certainly become slippery and slow going. Plus, road crews will be trying to pre-treat the roads as best possible, and that is made easier with less traffic. Winds will steadily increase during the day as well, reaching 30-40 MPH from the northeast at the coast by evening.
Friday Night- Snow will continue to increase in intensity during the nighttime hours. Along the coast, any mixing will be replaced by heavy snow no later than the wee hours of Saturday. That is important because the heaviest snow, falling at the rate of a few inches per hour at times, will come between midnight and about 8 AM. A few claps of thunder are even possible during the heaviest bands. Winds along the coast during this time will reach 40-50 MPH with gusts as high as 50-65 MPH at times. A blizzard officially occurs when sustained winds reach 35 MPH, and visibilities are reduced by a quarter mile or less, for at least three hours. That’s likely Friday night into early Saturday morning, especially near the coast.
Saturday- After about 8 AM winds will slowly start to relax. Snow will continue at a steady pace through at least early afternoon, gradually tapering off for good during the afternoon. However, travel will still be unfavorable until late Saturday afternoon or Saturday evening.
How Much Snow: Snowfall amounts will be quite impressive. For much of the South Shore and immediate coastline, including Hingham and Boston, expect a widespread 12-18″ of snow by Saturday afternoon. Areas away from the coast are likely to see 15-24″ of snow, with some towns picking up even more than that! Towns that see thundersnow, likely around I-95, stand the best chance of pickup up those amounts greater than 2 feet. South and east of Plymouth, where mixing will last longest, expect more like 6-12″.
Coastal Flooding: There are two high tide cycles that pose a coastal flood risk during the storm. Friday night’s 10 PM high tide is around 10 feet. With strong northeast winds expect a 2-3′ storm surge on top of that tide. Widespread moderate coastal flooding is likely. The 10 AM Saturday morning high tide is astronomically high at 11.5 feet. Expect more like a 2-3′ storm surge during that cycle. Moderate coastal flooding is likely at that time, with pockets of major coastal flooding along north facing coastal areas. Sandwich and the north side of Cape Cod will be particularly hard hit. Recall that moderate coastal flooding entails widespread road closures and minor structural damage. Major coastal flooding involves more widespread structural damage.
Stay tuned for more forecast updates as we get closer. I’ll be answering storm related questions here in the comments section, on the HinghamWeather.com Facebook page, and on my twitter page (@MichaelPageWx).