‘Sleet-Fest’ forecast for Friday leads into freezing weekend – CBS Boston

BOSTON (CBS) – Just days after our biggest blizzard of the year, there’s no respite from weary weather. As Bill Belichick would say, “we’re going to Friday.” This storm will be very different from last Saturday’s blizzard. In fact, I’m not even sure we can call it a hurricane. It’s like a frontal walkway or weather boundary. (Try describing that to news producers looking for a headline!). There will be no wind problem. There will be no coastal flooding, no big waves, no waves knocking down houses in Scituate. In fact, there won’t even be that much snow in southern New England!

So what’s the big deal?

Well, despite the mild weather on Wednesday and Thursday, we’ll still have a thick layer of snow when the rainfall arrives on Thursday, in the range of 6 to 12 inches in most areas. This “system” will be loaded with moisture. The total amount of liquid (rain, ice and snow) will be close to 2″, which is a lot of “things” falling from the sky. And on top of that, it’s going to be cold all weekend. The whole area sinks on teen Friday night and we won’t get out of our 20s Saturdays. So any standing water will freeze and we’re left with a mess. filled with ice.

Let’s back up a bit and take it part by part.

TIMELINE:

Rain arrived on Thursday, becoming steady and heavier in the afternoon and evening. Snow and ice are limited to central and northern New England.

Thursday night cold air began to push south. By midnight, we saw variable snowfall in parts of southern New Hampshire. By early Friday morning, sleet was active throughout Northern Mass., possibly as close as Boston and Mass Pike.

On Fridays, it’s a sleet festival in most of southern New England. Rain will continue to linger on the South Coast, Cape and Islands through the storm’s end Friday night. There will be some pure snow on the northern edge of the precipitation shield. The sleet will turn into snow as far south as around Boston before things start to taper off late Friday afternoon/night.

SLEET vs FREEZING RAIN:

Some brief thoughts on the effects of hail and freezing rain. We believe that for much of southern New England, sleet will be the primary type of rain (as precipitation changes) and not freezing rain.

Freezing occurs when you have mild air (above 32 degrees) above the ground but a shallow layer of frozen air underneath just above the surface. So when the rain falls, it hits the cold ground (streets, sidewalks, yards, driveways, trees) and instantly freezes. This is the most dangerous and difficult type of rain that, in larger amounts, can cause great damage to trees and power lines. All of our infamous ice storms, when you can lose power for days, are caused by freezing rain.

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Bubbles occur when you get a larger layer of cold air. Rain falls from above, forming a dense layer of the atmosphere that freezes underneath. Therefore, it has time to solidify into small pellets. These hit the ground and tend to bounce off things and have that pinging sound. Snow oil, in large amounts, can accumulate but much less easily than snow. Most importantly, it doesn’t build up on trees and wires so the risk of power outages is minimal.

ACCUMULATION:

As we are forecasting rain to hail for most of southern New England, accumulation will be low.

Up to 1 to 3 inches of hail and snow is possible in northern Massachusetts (north of Pike, mainly in counties north of Worcester and north of Middlesex).

In Mass. And the New Hampshire border 3 to 6 inches of snow and sleet could spill over Manchester, Concord and Lake Winnipesaukee.

(WBZ-TV Graphics)

Good news for skiers. The jackpot snow zone will be in the mountains, especially the Blue and White North. We predict 6-12″ in those areas with perhaps up to 18″ in some of the higher, northernmost peaks.

STRONG SECTION:

Temperatures will drop all day on Friday. By the end of the afternoon, the whole of southern New England had temperatures below 32 degrees and everything that had been dumped, any standing water, would have frozen. Any untreated surfaces and roadways will become very slippery. We stayed below freezing all weekend. Thankfully, we’ll see plenty of sun on Saturday and Sunday, so despite the cold temperatures, some ice melt is still possible.

(WBZ-TV Graphics)

Timing is critical and we’ll update you as new data becomes available. Stay tuned to WBZ-TV, CBSBoston.com and CBS News Boston.