BOSTON (CBS) – The weather forecast for snow and rain in southern New England this weekend was difficult to pin down.
In the past week the models have gone from nothing to a warm and windy rainstorm to a wintry northeast and back again. Currently, at the time of this writing, around 24 hours after the storm arrived, we still have a number of solutions that are not ideal.
Winter storm clocks were set up before this storm. These clocks are likely to be hoisted on Friday afternoon for winter storm warnings, increasing the probability of 6 inches + snow.
This forecast is more difficult than we’d like when it’s so close to the height of the storm. A wide range of model outputs show snow loads for central and eastern Massachusetts. While this cannot be completely ruled out, these raw model outputs neglect some elements.
First, these model editions are typically set at a 10: 1 ratio of 10 inches of snow per 1 inch of rain. Since only marginally supportive temperatures are expected for the duration of the storm, the ratio used by the WBZ-TV weather team is closer to 7: 1.
Second, the ocean is still pretty warm, ranging from 45 to 50 degrees, which is well above average for this time of year.
Any wind from the water (which is of course true in a northeast coast) will flood the coast with mild air.
In addition, there is really no source of cold air to speak of. Most of the time, to get a big blizzard in our area, you need a high pressure area in our north to pump the cold Canadian air south. It just doesn’t exist in this mess, so the storm has to create its own cold air by drawing it from the upper levels of the atmosphere. It has to snow on a really hard clip for this to happen, but it is possible!
Just right? Ha!
Let’s get to the point as best we can.
Some rain showers come Friday afternoon and evening, not that heavy. The showers continue from Friday evening to Saturday morning.
Between 7 a.m. and 12 noon on Saturday, the storm will begin to deepen south of Long Island and the precipitation should fill in and increase in intensity.
If there is to be a “climax” of this storm, it will come on Saturday afternoon and evening. This is clearly the timeframe to be observed. With the right storm trail and intensity, we would see heavy, wet snow fall across most of central Massachusetts by early Saturday afternoon.
The rain / snow line would likely collapse to some degree to the east later in the afternoon, turning the rain into wet, pasty snow closer to 128 and in Metrowest.
This is a low-confidence prediction because of the many moving parts, but here it is.
A solid snowfall for Worcester County in Middlesex County and southern New Hampshire could deliver 8 inches of snow. On some mesoscale strips, it is possible for snow to fall at a rate of 1 to 3 inches per hour.
As you get closer to 495 and 128, the amounts drop to 2 to 4 inches. The counties of South Shore and Northern Bristol and Plymouth will likely rain for the most part, with some light coatings mixing in.
If areas got more than 10 inches of this pasty snow, isolated power outages would certainly be possible.
Wind clocks apply to the south coast, the cape and the islands.
If the storm leaves the area, strong winds from the west could boost it to over 55 miles per hour. With these gusts of wind, isolated power outages are possible.
The tides will be astronomically low, so no significant problems with flooding on the coast are to be expected. Flood occurs around 2 p.m. Saturday and Sunday at 3 a.m., just before and after the peak of the winds.
As always, we urge you to stay tuned to WBZ-TV, CBSBoston.com and CBSN Boston before and during the storm – we have it all for you!