Yes, this IS happening. No last minute, out-to-sea track shifts, at this time tomorrow, our biggest snowstorm in 4 years will be underway.
The overall forecast has not changed much today. We have some minor tweaks, but the anticipated impacts and snow forecast largely remains the same.
The National Weather Service has placed our entire area under a winter storm warning for Sunday and Monday.
This is in place based upon the heavy snow totals that are expected and the severe impact to travel through Monday.
Timeline…
There may be some stray flurries early Sunday morning here and there but the true shield of snow associated directly with the storm will
move in from south to north across southern New England between 8am and 2pm.
Approximate first flakes in Boston and Worcester: 10am-Noon.
Massachusetts/New Hampshire border: Noon-2pm.
What could change? With such a cold and dry airmass in place, it may take an extra hour or two to saturate the air. If it isn’t snowing where you are by 11a or Noon, hang tight, it won’t be long.
Once the snow spreads over southern New England, it will ramp up quickly. By 3-4pm we will be entering the “teeth” of the storm and roads will become snow-covered.
The peak of the storm will occur from roughly 4pm Sunday through 1am Monday.
During this timeframe, visibility in some areas may drop below ¼ mile.
Some intense snow bands will form with snowfall rates of 1″ per hour or greater.
Some milder air (slightly above 32 degrees) will push northward and into southernmost Massachusetts after 7pm Sunday night.
This will be happening several thousand feet above our heads. In that milder layer, the snow will melt the snow to rain and then it will refreeze back into sleet pellets before hitting the ground.
The big question is, how far north does this layer of sleet make it? Currently we believe it will get to about Plymouth MA, but there is an outside chance it comes as far north as Boston late Sunday night.
Long story short, expect the snow to change to sleet and perhaps to rain for several hours late Sunday night over extreme southeastern Massachusetts.
After 1am Monday morning, the steady/heavy snow starts to become more scattered…
A dry slot will move up over portions of Connecticut, Rhode Island and southeastern MA. This will either shut off the precipitation completely or dramatically lessen the intensity.
Winds will be gusty out of the northeast along the Coastline.
A coastal front will form just west of Boston, near I95, marking the difference in temperatures between the upper 20s and 30s to the east and teens to the west.
East of the front, the snow becomes heavier and wetter for a time.
West of the front, it remains pure Arctic fluff.
Early Monday morning, the storm makes its closest pass to southern New England and then begins to head east, out to sea. The winds will veer to the north, and the coastal front will be swept away. The frigid, Arctic air will gradually push back over eastern and southeastern MA, and any standing water from the rain/mix area will freeze quickly.
Throughout the day on Monday, scattered areas and bands of snow will rotate from north to south . It will snow moderately in some areas, lightly or not at all in others.
There may be some locally heavy, ocean-enhanced bands of snow near the coastline.
After dark Monday night, the area of snow begins to rotate eastward, and the snow ends in central and western MA. The final few snow bands pass through eastern MA between 5pm and 8pm.
By that measure, I would expect the roads to deteriorate Sunday late afternoon and become snow covered quickly.
The most hazardous travel will be between about 5pm and 1am with a very slow, gradual improvement during the day Monday.
We are forecasting a widespread 12-20″ of snow across most of the area. Our largest storm in several years.
The exception being along the extreme South Coast, Cape Cod and the Islands where we anticipate some ice and rain mixing in at times.
In those areas we are forecasting 6-12″ and a much heavier, wetter snow.
It is always hard to predict whether there will be a few areas that “overproduce” with more snow than expected. We are highlighting two areas with the possibility of receiving slightly more than 20″ of snow in this storm.
#1- North Shore through Boston and immediate South Shore…this area is a classic location for the formation of some heavier bands to form thanks to something we call ocean-enhancement. Essentially, this is caused by very cold, Arctic air flowing over the much milder Atlantic Ocean (similar to lake-effect in New York State). On a northeast wind, this can cause highly localized, moderate to heavy snow bands along the immediate Coastlines and areas a few miles inland…
#2- North and west of 495, including the higher elevated areas in Worcester county…these areas are notorious for staying very cold throughout the storm. The colder the air temperatures, the higher the “fluff factor”. If we can get enough moisture back in this region, the light and fluffy snow can really stack up quickly!
Here is an approximation of how much snow will be in your backyard and driveway as time passes Sunday and Monday…
One more thing to watch…Snow accumulation also depends somewhat upon the type of snowflake that is falling.
Dendrites (those classic 6-sided picturesque flakes), accumulate the best while other shapes like needles and columns do not tend to stack up as well.
The shape of the flakes is dependent upon where the flake is created in the atmosphere.
The perfect looking dendrites are created in temperatures that are between -20 and -10 degrees, this is called the dendritic growth zone.
When snow is formed at temperatures above or below that layer, you tend to get odd ball shapes that don’t stack up and accumulate well.
We are somewhat concerned with this storm that some of the snow growth may NOT occur in this ideal dendritic growth zone. This COULD lead to snow totals underperforming if that occurs.
Outside of the South Coast, Cape Cod and the Islands, the snow in this storm is going to be very light and fluffy. This is largely good news as it is much easier to move around. In fact, you may even be able to clear you car off with a leaf blower in some of the colder areas!
This kind of snow also does not stick to tree limbs and power lines very well so, power outages are much less of a concern.
The one thing about snowfall in very cold temperatures is that it stacks up fast. You can easily get twice as much snow accumulation from a storm with temperatures in the teens than one with temperatures near 32 degrees (both having these same actual melted liquid content).
We have very little concern about the wind with this storm. We will see northeasterly gusts between 20-40mph right at the immediate coastline late Sunday night through early Monday. This is much lower than our typical strong and destructive nor’easters. Can we call this a nor’easter? Technically yes, but the winds will only be a minor issue.
A reminder that in order to achieve “blizzard conditions” you need to have 3 consecutive hours with sustained winds or frequent gusts at or over 35mph and visibility less than ¼ of a mile. That is not likely in the storm given the wind forecast. We may flirt with these types of conditions right at the coast at times but sustaining them seems unlikely.
Finally, the airmass behind this storm will be quite cold (what else is new). There will be very little melting next week. Temperatures are likely to stay below 32 degrees for the entire week.
As always, we urge that you stay tuned to WBZ-TV and WBZ.com for frequent updates before and during the storm. The WBZ NEXT Weather team has you covered!
Stay Safe and Go Pats!
TIMELINE FOCUS
This weekend’s storm is going to be a long-duration event. Snow is expected to fall with varying degrees of intensity for about 36 hours.
So, when does it start? When does it end? When should you clean up? Let’s dig in…
SUNDAY 8AM-NOON:
There may be some stray flurries early Sunday morning here and there but the true shield of snow associated directly with the storm will
move in from south to north across southern New England between 8am and 2pm.
Approximate first flakes in Boston and Worcester: 11am-1pm
Massachusetts/New Hampshire border: Noon-2pm
INTENSITY:
Light to moderate during the morning hours.
ACCUMULATION:
Very little accumulation expected, scattered coatings.
SUNDAY NOON-3PM:
The snow encompasses all of southern New England during this timeframe.
INTENSITY:
Light at first, intensity picks up quickly
ACCUMULATION:
Mostly coatings to an inch or so…up to 2″ well southwest
SUNDAY 3PM-8PM:
We enter the “teeth” of the storm. Visibility lowers significantly, and the snow really starts to stack up. Travel gets worse by the hour.
We may see some mixing with sleet/rain over the Islands.
INTENSITY:
Moderate to heavy
Some areas receive 1″+ per hour
ACCUMULATION:
Widespread 3-6″+ by 8pm
SUNDAY 8PM-Midnight:
The storm is at its peak, travel at its worst. Visibility less than ¼ mile in heavier bands. Winds gusty along the coastline.
Rain/sleet mix in along the South Coast, Cape and Islands.
A coastal front sets up near I95 and temperatures rise in eastern-most areas making the snow a bit wetter.
INTENSITY:
Heavy, potential for 1″-2″+ per hour
ACCUMULATION:
6-12″ across southern New England.
MONDAY 12AM-7AM:
Steady/heavy snow starts to become more scattered…
A dry slot moves up over portions of Connecticut, Rhode Island and southeastern MA. This will either shut off the precipitation completely or dramatically lessen the intensity.
The rain/mix line reaches its farthest northern location (likely around Plymouth).
Winds will be gusty out of the northeast along the Coastline.
Coastal front sits to the west of Boston, along I95 marking the difference in temperatures between the upper 20s to the east and teens to the west.
INTENSITY:
Starts heavy then becomes quite variable/spotty
ACCUMULATION:
10-16″ in all areas except South Coast/Cape/Islands
MONDAY 7AM-5PM:
The storm makes its closest pass to southern New England and then begins to head east, out to sea. The winds will veer to the north, and the coastal front will be swept away. The frigid, Arctic air will extend back over eastern and southeastern MA, and any standing water from the rain/mix area will freeze quickly.
Areas of snow now rotate from north to south but are scattered. It will snow moderately in some areas, lightly or not at all in others.
Watching for some locally heavy, ocean-enhanced bands of snow near the coastline.
INTENSITY:
Variable
ACCUMULATION:
12-20″ by the end of the day, again except for extreme southeastern MA.
Makes sense to do a driveway cleanup during the day Monday, just keep in mind that you could receive another coating to 2″.
MONDAY 5PM- 8PM:
The area of snow begins to rotate eastward…snow ends in central and western MA. The final few snow bands pass through eastern MA.
You can safely go out and cleanup the driveway without worrying about much additional accumulation.
MONDAY 8PM-TUESDAY
Done! Let the cleanup begin! Temperatures will be very cold Tuesday and all of next week, we probably will stay below 32 degrees right through next weekend.
In other words, no melting.
ACCUMULATION FOCUS
You may be looking at our snowfall forecast graphic and wondering a few things…
-12-20″ is a pretty big range, is my town going to be closer to 12″ or 20″?
-Where is the “jackpot” going to be? Who gets the most?
-Could some towns see more than 20″?
-Where is my town on that map? (ok, not sure I can help with that one, maybe try Googling it)
The purpose of this blog is to cover all that and more because the question we get more than any other before a big storm is, “how much is my town getting”.
First some overall thoughts on the WBZ official snow forecast…
It may look simple enough, but in fact, there is a lot going on “behind the scenes” in the WBZ office in order to put this together.
Some of the major factors complicating the overall snow forecast include…
-Sleet…does it happen, how far north does it come, how quickly and for how long
-Coastal front…a staple during classic New England snowstorms, creates a big temperature difference over a small area
-The fluff factor…the colder it is, the fluffier the snow and the more it stacks up
-The usual stuff like mild ocean temperatures, wind direction, elevated areas and the dreaded “heavy snow band” that can quickly ruin an otherwise great forecast
Let’s “dig” in…
AREA #1 MA SOUTH COAST, CAPE COD, ISLANDS
I’d say the biggest wildcard with this storm is the potential for sleet.
Sleet are those little ice pellets that go ping ping off your car and house. It doesn’t really accumulate nor does it stick to stuff, but it does bring a halt to the snowfall accumulation.
We expect a thin layer of warmer air (slightly above 32 degrees) to nose in about 5,000 feet above our heads Sunday night.
When this happens, the snow falling out of the clouds at much higher levels of the atmosphere passes through the warmer layer, melts into rain, and then refreezes as it falls back into cold layers near the ground level.
Currently, we think this warm layer will make it about as far north as Plymouth, MA and therefore, we have lowered our snow amounts from Plymouth area southward.
BEHIND THE SCENES, our weather team has been discussing whether we should drop the snow forecast to 3-6″ over Martha’s Vineyard and Nantucket due to the mixing arriving there earlier.
We haven’t pulled the trigger yet, but it remains a possibility.
The snow in the 6-12″ zone will be much different from most other areas. It will start off rather light and fluffy early Sunday but temperatures will be on the rise all day (and night).
So, picture this “snow sandwich”…
Bottom layer: bit of fluff
Next up: heavy/wet snow
Next up: sleet pellets with perhaps a touch of rain
Lastly: a bit of snow on top (frosting) coming later Monday
I dare anyone to try and forecast what will be left on the ground post-storm in this area. Let’s call it a mess and move on.
AREA #2 SOUTH OF THE MASS PIKE INCLUDING THE SOUTH SHORE AND NORFOLK COUNTY
This area is within our 12″-20″ zone.
BEHIND THE SCENES, our team is concerned about three things here.
-If the sleet comes a bit farther north, towns like Taunton, Middleboro and Marshfield might not make it to 12″. We have toyed with dragging the 6-12″ line a tad farther north, could still happen.
-A coastal front will setup Sunday night and most of the towns here will warm up from the teens into the upper 20s and low 30s for several hours. This will make the snow wetter and heavier for a time and could weight down what has already accumulated. For that reason, it seems unlikely that this area “overperforms”.
-Lastly, there could be some ocean-enhancement. As the cold air flows over the milder ocean, sometimes this can create some heavier bands that drop several more inches in coastal towns (same idea as lake-effect but not as intense). These are near-impossible to predict but could lead to neighboring towns having a rather large disparity in snow amounts.
One final though in this area…there will likely be a “dry slot” moving in late Sunday night that will shut off or severely lighten the precip. for several hours into early Monday.
So basically, you get a big thump of snow Sunday afternoon and evening and then it may just suddenly shut off.
AREA #3 NORTH SHORE, IMMEDIATE BOSTON AREA, UPPER SOUTH SHORE
We feel pretty confident with our forecast here, I would guess that these towns end up in the middle or higher end of the 12-20″ range.
Coastal front factors in here too, warming temperatures up 10 degrees or more Sunday night.
There is a significant chance that late in the storm, during the day Monday, some bands of snow will rotate from north to south over this area. This COULD end up pushing some towns here over the 20″ mark. Therefore, we have labeled this area as a potential “jackpot” zone. This is exactly what happened in the Presidents’ Day storm in 2003. A last-gasp, localized band of snow dumped several inches in Boston, pushing the City over the record for a single snowstorm previously held by the Blizzard of 1978.
AREA #4 NORTH OF THE PIKE, AREAS CHARACTERIZED BY THE TERM “NORTH AND WEST”, WORCESTER HILLS, 495 AND ROUTE 2 AREA
Lock it in, this area may be the easiest call of them all. No doubt towns here will stay very cold the whole time and nothing but fluff will fall here.
I would expect the higher end of the 12-20″ range.
This is our second and final potential “jackpot” zone. This should come as no surprise to those living here, this is the true snow-belt of southern New England.
More often than not, this area always over does it.
Definitely wouldn’t be shocked if several towns here went over 20″ and ended up closer to 2 feet of pure Arctic fluff.
