A Blizzard Warning has been issued for the Cape, Islands and the South Shore as New England braces for a major snowstorm that is expected to hit on Thursday.
There will be snow, and plenty of it. This morning’s snow accumulation forecast we aired from 4:30 to 7 a.m. on NBC Boston and necn did take the surge of cold into account – and the cold surge plays a role in our storm forecast.
Storms travel along boundaries between warm and cold air, so the heftier surge of cold air means a storm track that puts areas south of Boston in the cross-hairs for highest snowfall amounts around or locally over a foot, with a significant but lesser snowfall north of the Massachusetts Turnpike, and snow plows likely coming out all the way into the mountains of Northern New England.
Winter storm warnings and watches are already in effect for much of New England.
Expect snow to begin between 5 and 8 a.m. Thursday, west to east, respectively, for the vast majority of us, and continue all the way through Thursday evening before coming to an end Thursday night.
A north wind will user in cold temperatures for this storm – 20s south and 10s north – which means snow will quickly stick to and accumulate on roads, making travel treacherous from morning through evening Thursday.
Heavy snow at times will combine with wind gusts to 45 mph on Cape Cod Thursday for possible blizzard conditions, though there is a bit less certainty on whether that criteria of 3-hour duration for 35 mph wind gusts and blinding snow will be reached.
Nonetheless, we believe it is a possibility on Cape Cod for a time Thursday afternoon.
Total accumulations are likely to be near a foot from the South Shore through much of Rhode Island into Southeast Connecticut, half a foot or so north of the Mass Pike to extreme Southern New Hampshire and lesser amounts of a few inches in the North Country lakes and mountains.
MEMA says snowfall will be heavy at times, falling at a rate of 2 to 4 inches an hour, with thunder snow a possibility. The morning and afternoon commutes are expected to be impacted, with blowing snow that could produce visibility of a quarter mile or less. Whiteout conditions are possible.
But before this next storm hits, let's look back on the chaos on area roads Wednesday morning.
On a day forecast to rise into the 50s for many – and still likely to do so along and South of the Massachusetts Turnpike – how can such a treacherous start to the day result?
Tuesday morning, some 24 hours prior to the ice event, I did not have widespread ice in the forecast. It appeared warmth would slowly work through Southern New England overnight Tuesday night, following Tuesday’s snow, bumping most temperatures above freezing and into the 30s.
The first signs of a major change for the colder, however, began by Tuesday afternoon. I was snow blowing at my home in Haverhill, in the Merrimack Valley, around 4 p.m. when the anemometer started spinning like crazy and the wind vane pointed north-northeast.
The wind howling was much stronger than I’d expected it to be.
That’s when I saw we had a problem: how could a north wind gusting to 30 mph and driving the temperature below 20 degrees reverse sufficiently to warm the surface some 20 degrees in the other direction by morning? The answer became clear: it couldn’t.
My ride to work from 2 to 3 a.m. spans 48 miles spread over three interstates into Boston’s MetroWest – below freezing but treated and all wet, all the way. Road treatments held up through the night.
To our west, radar indicated an area of showers falling into sub-freezing air: freezing rain was moving east. Fifteen or twenty years ago, this would be an immediate problem for all of our roads - now, road chemicals and treatments have advanced and we see so many times we meteorologists caution to beware of icy roads, only to find a few slick spots on the back roads.
As freezing rain showers fell, the first 60 minutes of showers brought no reported issues and continued wet roads – then, the scale tipped. Just enough rain fell in the final 30 minutes of showers to cleanse the interstates of treatment, and with temperatures below freezing, that’s all it took.
This happened at 5 a.m., and as the back edge of the showers moved through communities, one by one the crash reports came in – all in areas that had seen more than an hour’s worth of rain showers - all in areas that had previously seen wet roads until those last 30 minutes of showers - and just in time for commuters to hit the roads.
An interesting question is: how do we avoid this? Surely, the late notice on cold air plays a significant role. The expectation was for rising temperatures, but it became quite clear during the overnight that cold air was not relenting.
From there on, this truly was a perfect storm of conditions for road ice, and with no road temperature or treatment data for individual interstates in Massachusetts made public, meteorologists and travelers alike are "flying blind" in conditions like these.
What kind of chemicals were applied? Was rainfall light enough to preserve road chemicals, or did they wash away? What happens next to prevent, or at least improve upon, situations like this is meteorologists like Yours Truly will analyze the weather conditions that led to this, but at least for the time-being we will continue to have a blind spot when it comes to road temperature and treatment data.