Unlike the last storm, which we admittedly underestimated, this storm is likely not going to live up to expectations for parts of the region, mainly north and west of Boston.

As the storm starts to move in this afternoon and evening, there is a lot of dry air in place. Dewpoints are only in the upper teens and 20s across much of the region. So, as the moisture from the storm moves in, it’s moistening up the atmosphere slowly, but anything that falls from the clouds is evaporating before hitting the ground.

Eventually, the moisture will overcome this drier air, but the storm is also tracking a little farther to the south than we were thinking yesterday. As a result, snowfall totals will be considerably lower north and west of Boston than our previous forecast. Of course, this also means that there could be a bit more snow than we were thinking south of Boston, especially across Cape Cod, though some rain could still mix in there, which would limit amounts a bit.. This scenario was first hinted at by the ECMWF model 2 days ago, and most meteorologists thought of it as an outlier, since most of the other model guidance was painting a snowier scenario. We tended to discount it as well, but in the back of our minds, we kept hearing a phrase that a noted meteorologist has repeated over and over to us “Ignore the Euro at your own peril.”

So, with that in mind, we are revising our forecast to be closer to what the European model is showing (but not exactly):

Southeastern Massachusetts/Cape Cod: 5-9″ (possibly less on the Outer Cape if rain mixes in)
I-95 Corridor (Boston/Providence): 4-7″
MetroWest: 3-5″
Merrimack Valley/NH Seacoast: 2-4″
Southern NH (Nashua/Manchester): 1-3″

This will still be a fairly wet snow south of Boston, so keep that in mind when you go out to shovel it tonight or Thursday. Once the sun comes up, thanks to the higher sun angle, any additional accumulations are not expected on paved or treated surfaces. Everything should wind down and end completely by early Thursday afternoon.

As this storm moves into Atlantic Canada, and upper-level low will settle into the Northeast for Friday and Saturday, keeping us cloudy and cool. An impulse riding around the system may bring some light snow and snow showers in on Saturday, but accumulations will likely be on the light side, if we get much at all.

“Once more unto the breach, dear friends, once more.”

At 12:15 EDT this afternoon, the sun was directly over the Equator, marking the Vernal Equinox, or as it is more commonly known, the start of Astronomical Spring. Here in New England, astronomical seasons don’t have really have much influence on the weather, at least the start and end of those seasons. Take this week for example. Tomorrow is the first full day of spring, but we’re expecting another snowstorm. Yup, that’d be the fourth one this month.

There’s actually a storm passing well south of New England today, so in a sense, we were spared a bit. It’s producing some rain and snow across the Mid-Atlantic states and sending a veil of high clouds across New England, dimming the sunshine this afternoon. Another storm will quickly follow on Wednesday, thickening up the cloud cover. Let’s start out by saying that this storm will not be as bad as the ones we’ve had earlier this month. We’re not expecting blizzard conditions. Oh, we’ll still have a decent amount of snow, strong winds, and some coastal flooding issues, but not at the magnitude of the earlier storms.

We’ll start with the winds and coastal flooding. Tides are astronomically high again this week, so the biggest concern will be at high tide at northeast and north facing beaches, especially the high tides early Wednesday and Thursday morning, as well as Wednesday afternoon. A coastal flood watch is in effect for the early Thursday morning high tide across Plymouth County as well as the Cape and Islands. As for the winds, sustained winds of 20-30 mph are expected, especially along the coast, with gusts of 40-50 mph, perhaps as high as 60 mph across the Cape and Islands, Southeastern Massachusetts, and parts of Rhode Island. Combine that with heavy, wet snow (more on that in a moment), and yes, power outages become a concern once again.

Now, for the part that most of you care about – snowfall. The snow should develop during the afternoon hours on Wednesday. While it’ll be snowing during the afternoon rush hour, it shouldn’t cause too many problems (the people on the roads, however, probably will). With the higher sun angle at this time of year (equivalent to mid-September), and only light snow expected during the daylight hours on Wednesday, accumulations will be fairly light, especially on paved surfaces. Once the sun sets, steadier snow will move in, with the bulk of the accumulating snow expected Wednesday evening into Thursday morning. While the accumulating snow will be all done Thursday morning, light snow and snow showers may linger into the afternoon. We also will likely be dealing with a rain/snow line. A change to rain seems likely across Cape Cod for a while Wednesday evening, with that changeover likely penetrating into parts of southeastern Massachusetts. The question is – how far? Right now, we don’t expect it to get past Route 44, if it even gets that far.

That brings us to the amounts. With temperatures close to freezing, this is going to be a heavy, wet snow, so keep that in mind when you go out to shovel or fire up the snowblower. Here’s what we’re thinking:

Cape Cod: 1-3″, highest totals on the Upper Cape
South Coast: 3-5″
South and East of I-95: 4-7″
Metro Boston/MetroWest/Merrimack Valley/North Shore: 5-9″
Southern NH (Nashua/Manchester)/NH Seacoast: 4-7″

Once this system pulls away, an upper-level low pressure area will slowly move across the Northeast, which may give us some additional snow showers on Friday and Saturday, but we’re not expecting much accumulation (if any), with those. Beyond that – right now, the models aren’t showing any big storms over the next 2 weeks, but that is always subject to change. Remember, just a couple of days ago, most of the TV talking heads told you that this storm was going to stay offshore and we didn’t have to worry about it. As for when we can expect some actual “Spring” weather – well, the pattern looks to remain chilly right into at least early April.

So, remember just 24 hours ago when we said that we weren’t buying all of the ridiculous numbers being floated out there because we expected the models to shift the storm a bit eastward? Yeah, the opposite happened.

Hey, we’re the first ones to admit when we are wr….wro…..wro….when our forecast starts going off the track. We wait until we’re fairly sure we’ve got a good forecast before we publish, because we want you to have the best info available. Well, in this case, that didn’t work out. Luckily, we still haven’t gotten into the storm, so we have time to fix things.

The basics that we outlined last night still hold true. Low pressure will move up the East Coast and rapidly intensify, passing south and east of Cape Cod later Tuesday. Strong winds are likely, especially along the coast. Sustained winds of 20-30 mph with gusts to 50 mph inland and possibly 70 mph along the coast. We may have understated the coastal flood threat a bit, but still, any coastal flooding will be minor in nature and confined to right around high tide.

Even the timing is still close to what we were thinking last night. Precipitation should develop near or just after midnight, and quickly get heavy. Blizzard conditions are likely, mainly along the coastline, from daybreak through early afternoon. Snowfall should start to lighten up after midday, but likely doesn’t completely end until late evening or even close to midnight Tuesday night.

That brings us to the snowfall amounts. There are still some models that are showing amounts that border on ridiculous. As you should know by know, our forecasts, while filled with sarcasm and satire, try to be level-headed, not ridiculous. How much can you expect?

Outside of I-495: 6-12″
Merrimack Valley/Southern NH/NH Seacoast: 8-14″
Most of the remainder of Eastern Massachusetts and Rhode Island: 12-18″

The “jackpot” is likely to be across portions of Plymouth County and onto Cape Cod, where some totals of 18 to perhaps 24″ are possible. The big question here is whether any rain mixes in. This is especially possibly across the Outer Cape and Nantucket. If there is any rain, that will knock accumulations down.

Once the storm moves out, an upper-level low pressure area may trigger additional snow showers on Wednesday and again Thursday (and possibly Friday too). Oh, and since you’re all sick of snowstorms by now, depending on which model you believe, we could have as many as 3 more between now and the end of March. We’ll worry about each of those as they become a threat (or don’t).

You’re heard the phrase a million times: “March comes in like a lion and goes out like a lamb.” Well, the first half of that statement certainly was accurate this year, as much of the Northeast took a beating from last Friday’s storm. While many places are still trying to recover, we’ve got another one on our doorstep, and this one is promising to be more white than wet for much of the region.

The low pressure system that brought blizzard conditions to the Northern Plains and Upper Midwest over the past 36-48 hours will cross the Ohio Valley this afternoon and evening. By tonight, a secondary area of low pressure will develop off the North Carolina coast, and rapidly strengthen as it heads up the East Coast. It will likely pass very close to, possibly right over Cape Cod late Wednesday night, then move into the Gulf of Maine on Thursday. The exact track of the system will play a gigantic role in determining how far inland the rain/snow line penetrates. Some models keep the storm south and east of Nantucket, which could keep the rain/snow line confined to southeastern Massachusetts. Some models bring the storm across southeastern Massachusetts, with the rain/snow line getting as far inland as Springfield, MA and Manchester, NH. These are the two extremes, and much like Goldilocks and the Three Bears, we’re looking for something more in the middle.

There are a few different aspects of this storm that we need to worry about, depending on where you are located – strong winds, heavy rain, and heavy snow. We’ll start with the winds.

Many parts of the region, especially along the coast and in southeastern Massachusetts and Rhode Island are already sensitive to hearing a forecast for strong winds, after last Friday’s system took down so many trees and knocked out power to hundreds of thousands of residents. Thankfully, winds won’t be as strong with this storm, but they’ll still be capable of causing damage, especially to trees already weakened by the last storm. Winds will pick up during the day on Wednesday, likely peaking Wednesday night into early Thursday. Sustained winds of 25-40 mph, with gusts to 60 mph are expected,especially along the coast. Luckily, tides are not as high as they were a few days ago, so coastal flooding isn’t as much of a concern, though some splashover is certainly possible around the time of high tide. As the storm passes by early Thursday, winds will shift into the northwest and start to ease. However, this storm will likely move into Atlantic Canada and not move much for a few days, so we may still be dealing with gusty winds (just not as strong), right through Friday.

Next up is heavy rain. As we mentioned earlier, the rain/snow line is still a big question. However, in areas that stay all rain or mostly rain, such as Cape Cod, parts of southeastern Massachusetts and Rhode Island, rainfall will be heavy. Many places could see more than an inch of rain, possibly even 2 inches in spots. These are areas that saw 2 to as much as 5 inches of rain from the last storm. The ground is still saturated in parts of the region, and most of the rivers and streams remain fairly high. If you add another 1 to perhaps 2 inches of rain in a short period of time, you’re looking at more flooding in some areas.

Now, to the part that most of you want to know about – heavy snow. As the last paragraph and the map above show, this system will contain plenty of moisture. Away from the coast, temperatures will be near or just below freezing. That means that moisture will fall in the form of heavy, wet snow. The general rule of thumb is that 1 inch of rain equals about 10 inches of snow, but that is dependent on temperature. That’s why when temperatures are in the teens you get a fluffier snow where 1 inch of rain could mean 20 inches of snow. In cases like this, where temperatures will be close to freezing, that ratio could be closer to 8-to-1 (or even lower). Still, even at 8-to-1, you only need an inch and a half of rain to get a foot of snow. Complicating things is the rain/snow line. Places that see rain mix in will get significantly less snow than nearby areas that have no rain at all. Our best estimate right now is that the rain/snow line gets as far inland as Interstate 95, possibly a few miles farther. As the system passes by on its way into the Gulf of Maine on Thursday, that rain/snow line will crash southeastward towards the coast, changing everyone back over to snow before everything winds down Thursday afternoon. So, what does that mean for amounts?

Cape Cod/Southeastern Massachusetts: Less than 1″
I-95 corridor: 2-6″ (highly dependent on the rain/snow line)
MetroWest/NH Seacoast: 6-12″ (lightest amounts south & east where some rain could mix in)
Merrimack Valley/Southern NH: 8-14″, isolated heavier totals.

Finally, there’s the timing of this system. Snow will develop across the region around midday Wednesday, give or take an hour or two. Due to the higher sun angle at this time of year, it will have trouble accumulating on pavement at first, though grassy areas could see some accumulation. The snow will quickly change to rain across southeastern Mass, southern Rhode Island, and Cape Cod. The rain/snow line will continue moving northwestward, likely reaching the I-95 corridor near the evening rush hour. At the same time, the steadier and heavier precipitation will arrive. During Wednesday evening and night, snowfall may accumulate at the rate of an inch or more per hour. If you don’t have to be out Wednesday night north and west of Boston, then don’t. Driving conditions will likely be rather poor. The rain/snow line will crash to the coast early Thursday morning, with the steadiest precipitation winding down towards daybreak. Occasional snow showers may continue off and on through the afternoon, but most of the accumulating snow should be done in the morning. Expect a lot of school cancellations on Thursday, especially north and west of Boston.

If you’re wondering if this is winter’s last gasp – don’t count on it. Some of the models show the potential for another system early next week, but it’s still several days away, and there’s plenty of disagreement among the models as to the evolution of that system. We’ll worry about that, if we need to, this weekend.

You’ve heard the news talking about it all week, and we mentioned it in our Weekly Outlook. A storm is coming on Friday, and it’s going to be a big one.

The biggest impacts from this storm will be felt along the coastline. We’ve already got astronomical high tides due to the full moon we had this week. As in the storm churning up the Atlantic and strong winds (more on that in a moment), and you’ve got a recipe for major coastal flooding. Parts of the coastline, especially east-facing shorelines, could see flooding worse than they saw with the storm in early January. Coastal flooding was already observed during the Thursday afternoon high tide without any impacts from the storm. What do you think is going to happen when you have onshore winds of 30-50 mph and 20-40 foot seas? Yeah, nothing good.

As we mentioned above, strong winds will impact most of the region starting late Thursday night and especially on Friday as the storm begins to intensify in the waters south of New England. High Wind Warnings are already in effect for much of the region. Sustained winds of 25-45 mph with gusts of 60-70 mph are likely, especially near the coastline. Some gusts in excess of hurricane force are possible, especially across Cape Cod. With winds this strong, power outages are likely, so make sure you are prepared for that possibility. Winds may start to diminish a little on Saturday, but as the storm heads southward and grows even larger, it will continue to produce gusty winds across the region right through the weekend.

In addition to the damaging winds and coastal flooding, heavy rain is also expected across the region. Rain will move in after midnight tonight, and continue for much of the day on Friday, heavy at times. The storm is drawing moisture northward from the Gulf of Mexico and the tropics, and as it moves into the relatively cooler air in place here, it will wring it out across the region. We’re looking at rainfall totals of 1 to 3 inches across the region, with some heavier amounts possible, especially across southeastern Massachusetts and Rhode Island. We’ve already had a wet start to the year, and the ground is close to saturated, so this will likely result in flooding in many areas. Rivers are also running fairly high, especially for this time of year, so river flooding will also become a concern.

Now we get to the tricky part of the forecast, where the greatest uncertainty lies – snowfall. There’s not a lot of cold air in place when the storm moves in, and we don’t have a big high pressure area to the north to help keep any cold air around. However, there is some cold air aloft, and as the system gets cranked up, it may try to tap into that cold air. As we get into some of the heavier bands of precipitation, it may drag some of that cold air down, changing the rain to snow in some areas. This isn’t the type of thing we can predict well in advance, so trying to pinpoint now is futile. However, don’t be surprised if some places change over to snow for a while during the day on Friday. Of course, some of the higher elevations, especially in the Worcester Hills, Monadnocks, and Berkshire, should have enough elevation to have quite a bit of snowfall from this system. It will be the heavy, wet snow that nobody likes either. You know, the type that weights down tries and power lines, making it even easier for them to snap when you get wind gusts of 50 mph or more. The other thing we’re concerned about with snowfall is what happens on the backside of the system. As the storm starts to pull away late Friday, colder air will settle in behind the system. The questions are: 1. How quickly does that cold air move in? and 2. How much precipitation is still around? Right now, we wouldn’t be surprised to see some locations pick up a quick 1-3 inches, possibly even more. There’s also a chance that the colder air moves in too late, and many places see little to no snow at all. The worst-case scenario, and we’re not completely ruling it out yet, is that places change over to snow in a burst of heavy precipitation during the afternoon (like we mentioned above), and never change back. If that were to happen (and the place where that would be possible would be mainly north and west of Boston), then very heavy snowfall amounts would become more likely. For the record, we’re not expecting this, but we are a little wary that it’s at least possible.

By Monday, high pressure builds in, and everything calms down. We may have another storm to deal with towards the middle of next week, but we’ll worry about that one after we get through this one.