Closing In…

The second major snowstorm in just over 2 weeks is now on final approach to New England. The beast is being born off the Mid Atlantic Coast now, and a very rapidly-deepening low pressure center will result, tracking northeastward, passing just southeast of Cape Cod Wednesday morning. This continues to look like a progressive system, that is, one that is not going to slow down or stall. Nevertheless, the rate of strengthening, track, and available moisture will be enough to crank out major snow for just about all of Massachusetts and southern New Hampshire.

Again, the wildcard remains the issue of how much mixing and rain will occur over Cape Cod. It still looks like most of the mix/rain will be confined to the Outer Cape, including Chatham. Snow amounts could range from as little as an inch or 2 near Chatham building up rapidly to around 10 inches near the Cape Cod Canal. For the remainder of Massachusetts and southern New Hampshire, it is now a pretty safe bet that all areas will see 10 or more inches of snow. The upper limit of accumulation expected has been hard for me to determine, as I have been concerned about the speed of the storm being too fast to allow the amounts you may have seen in some places to verify. That said, there is enough potential with this system that I will set my widespread upper accumulation limit at 16 inches.

Some specifics…

Once snow gets underway, look for a fairly rapid drop in visibility from south to north across the region, southern MA first, southern NH last, between 1am & just before dawn.

There should be up to a few inches of snow on the ground in many areas, especially in MA, by dawn.

Thundersnow remains possible during the heaviest snow in the morning hours. Snowfall rates of 1 to 2 inches per hour can be expected for much of the morning, but can reach 2 to 3 or even 4 inches per hour during thundersnow. These extreme rates do not usually last too long, however.

Blizzard conditions? 3 or more hours of sustained 1/4 mile or less visibility is possible, especially near the MA East Coast, as winds there will be steadiest and strongest (northeast to north 25-40 mph with higher gusts). Winds will be gusty inland, but not as strong as near the coast. Winds closer to Cape Cod may gust over 50 mph to even near 60 mph at times.

Tides… Astronomically low tides should limit flooding problems this time, in contrast to the storm of December 26-27. There will be some splashover and mostly minor flooding. But it also appears that the high tide and the strongest part of the storm will not coincide, which will further limit flooding.

What can go wrong with snow amounts? 2 things: If convective snowbands (thundersnow) are more prominent, snow amounts can be higher than forecast in some locations (isolated amounts over 16 inches). Also, this low pressure area will be deepening so rapidly, it may act almost like a tropical cyclone for a while. When this occurs, you sometimes see drying in the mid levels of the troposphere. That is, the air around where the snow forms can dry out, and you see lighter areas or even holes in the snow areas on the radar. Something similar to this happened in the last major storm, cutting down on snow amounts in central MA. This is something to watch for as the low pressure area makes its closest pass.

Any way you look at it, most of us are in for a good belting of snow and wind. Travel is not recommended, at least Wednesday morning through mid afternoon. Anyone that has to be out should allow alot of extra time and use extreme caution.

930pm Tuesday 1-11-2011

Storm Update

The National Weather Service has issued a Winter Storm Warning & Blizzard Warning from 2am thru 8pm Wednesday. The timing of this storm looks similar to what I discussed in the previous blog, so I won’t get into that again.

I have added a little to the snow totals, due to a slightly colder solution and a fluff factor of accumulating snow. Total snow across eastern MA, except Cape Cod, should be in the 10-16 inch range. It’s not out of the question that a few isolated 17 or 18 inch amounts are seen. I still think the majority of the amounts will come in at 14 inches or less, due to the quick movement of the storm.

Also, do not be surprised to hear thunder during the heaviest snow Wednesday morning. It is during these periods of heavier snow that blizzard conditions are most likely.

Another update will follow this evening!

Nature Raises A Snow Gun

Hi faithful blog readers! I’m going to keep this relatively short, because there is not a great deal of change in the thinking I expressed on the previous blog entry. As expected, the computer models waiver back and forth one way and another way with the storm track and precipitation/snow amounts regarding the developing storm. Sparing you the technical psychobabble, what I will say is that I still feel that the fast-movement of this storm and the fact I believe the models are overdoing the precipitation amounts, I am going to keep my snow totals a bit lower than the ones you’ll see on TV. I have bumped them up a touch since the last update to 6-12 inches for most of the Boston area. There is a slight chance that a few spot heavier amounts can occur underneath very heavy snowbands as a deepening storm passes just southeast of Cape Cod. This may also result in thundersnow (a few flashes of lightning & muffled thunder rumbles during the heaviest snow Wednesday morning).

The timeframe for this storm: Snow starts 3am Wednesday, plus or minus 2 hours, and ends 9pm Wednesday,  plus or minus 2 hours. The heaviest snow should fall during the morning. Mixing and some rain should be confined to the Cape & Islands, and possibly the immediate coast to the south of  Boston, due to warmer air off the ocean. Elsewhere, colder air should support mainly snow.

Look for updates tomorrow as we get closer to the event.

Winter Week

By most standards this will be a fairly simple week of weather, as the early and late parts of it will be mainly dry and chilly. It’s the middle part that gets tricky, as a storm will be chugging our way from the southwest.

As is often the case, we’ll be dealing with a few pieces of energy coming together to form a new storm along the coast at midweek, the track of which will ultimately determine what happens in the Boston area. In the midst of conflicting model data tonight, I’ve come up with a best-guess solution that will take a developing storm from the Mid Atlantic Coast Tuesday night to just southeast of Cape Cod by Wednesday morning. This system will have alot of energy with it and a very strong slug of moisture, but should be moving along rather progressively. Some mixing due to warmer air at the surface from the ocean may get involved along the coast mainly south of Boston, and especially over Cape Cod.

With all of this in mind, expect snow to begin in the pre-dawn hours of Wednesday, be heaviest during Wednesday morning, then slowly taper off through the remainder of the day. Due to the progression of this system, and the fact that I think the precipitation may be somewhat overforecast by the computers, I’ll start out by predicting a widespread 5 to 10 inches of snow for a good swath of eastern MA including Boston, with lesser amounts especially along the coast as you head south, dropping down to 1 to 3 inches over Cape Cod, where wetter snow & a period of rain will likely occur.

Behind this system, the 2nd half of the week looks dry & rather cold.

Looking well out into the future, a system may bring some snow showers Sunday, and provide at least a chance of some flakes in the air for the Patriots / Jets playoff game. It’s a long way off but we’ll see how it goes as we get closer.

There are signs of a more significant outbreak of cold air near or just after MLK Jr. Day.

Complex Setup May Seem So Simple

We continue to be in a complex weather pattern thanks to continued blocking. The computer models continue to have their issues resolving events in this weather pattern. What started out looking like something that may have been similar to the recent snowstorm has evolved into looking like something far less impressive as the model runs have gone by.

This still is a fascinating setup, from a meteorological perspective, however, as we’ll be watching several areas of low pressure and a trough connecting 2 of the main low pressure areas (a norlun trough) all producing areas of snow that will be around the area Friday through early Sunday. Even with this complexity, when it comes right down to the details of what you see, it may be that any given area  just sees a few periods of snow over this time, not amounting to all that much.

Complex pattern … Simple result? That’s weather.

Breaking it all down, the best guess as to what is going to happen in the Boston Area and southern NH is that elements of ocean-effect snow will break out mainly from Boston north during the day Friday, with some accumulation most likely in the North Shore area of MA westward across the MA/NH border. Another area of snow, associated with the trough  mentioned above, will be lifting slowly northeastward into southwestern New England, but may be weakening as it finally reaches eastern MA at night. Some accumulation is still possible from this area of snow. Finally, one of the low pressure areas offshore may intensify enough to throw yet another area of snow into parts of eastern MA, this one favoring the Boston area southward, during Saturday night. After all of this, a generalized 1 to 4 inches of snow can be expected, none of it coming too quickly, and none of it accompained by strong winds or anything similar to the recent storm.

I will watch the evolution of all of this and update by late Friday.

New Regime

After 11 months of above normal temperatures in Boston (January-November), making 2010 Boston’s warmest year on record, it appears we have reversed the trend. December 2010 was the only month of the year to average colder than normal, and thanks to a major snowstorm on December 26-27, snowfall for the month ended up above normal.

Looking ahead into the first couple weeks of the New Year, January 2011, despite starting with a mild New Year’s Weekend, is heading into colder territory once again. All the best indicators point to below normal temperatures during the next 10 days to 2 weeks. This is the result of a blocking pattern continuing to be the dominant force in driving our weather here. To refresh, this blocking pattern features a stubborn area of high pressure over Greenland, occasionally expanding into northeastern and east central Canada. This blocks cold air crossing Canada from moving eastward, and forces it southward into the US. In response to the high pressure area to the north, a low pressure trough is carved out over the eastern US, and though it oscillates and occasionally lifts out, its dominance is responsible for the chilly & sometimes stormy weather that the East Coast states have been enduring.

It appears that this general pattern is not about to go anywhere, and can be expected into the middle of January.  This should also result in a few more winter storm threats during the next couple of weeks. The next threat in the pipeline comes to our area by the end of this week, when there is some significant potential for accumulating snow. With a few days to go before this potential event, the best guess on a timeframe for a snow threat will be later Friday & Saturday. Computer models continue to show several possible scenarios, as is expected when the threat is still several days away. There are indications that whatever storm does evolve may be slow-moving for a time, making the potential significant for a longer-lasting event. This will be fine-tuned over the next few days and you can follow the developments in future blog entries.

In the shorter term, after a bright & chilly Monday, expected a slightly milder but also somewhat cloudier Tuesday, a result of milder air moving in mainly aloft. A cold front will cross the region Tuesday night & early Wednesday, and may produce a few snow showers as colder air gets reinforced for midweek. This will set the stage for the potential late week winter storm.

Happy New Year to all of you!

Winter Takes A New Year Nap

You’ll notice almost a hint of spring in the air during the final day of 2010 & the first day of 2011. This will be due to a high pressure ridge and associated mild air over New England, somewhat of a readjustment of the pattern in the wake of the big winter storm of a few days ago.

But will this milder weather last? It does not appear so. Most reliable indicators point to a rapid return to the pattern we have been in during recent weeks, with a blocking high pressure area over northeastern Canada and Greenland, and a low pressure trough over eastern Canada. This setup supplies the US Northeast with frequent spells of colder than normal temperatures. If the blocking is too strong, storms tend to miss us to the south. If the blocking is a bit weaker, the threat of storms increases. It’s a little too early to be sure what type of precipitation pattern we’ll be in during this next round of blocking, but at least the early part of the stretch is likely to be drier versus stormy.

When will the cold air return? It will begin to arrive behind a cold front which will pass through the region on  Sunday. The air ahead of and along this front will be warm enough so that any shower activity with the front will be in the form of rain. After the front goes by, some lingering moisture with colder air will provide a threat of snow showers Sunday night. At this time, any snow is not expected to cause travel problems, though we must always be on the lookout for a heavier snow shower or squall during this time of year when cold air is moving into the region.

The balance of next week looks as if it will be colder & drier than normal, with a fairly peristent west to northwest flow of air over New England.

Happy 2011 to everybody!

Tranquil, milder end to 2010…

The storm’s gone. The winds, cold, & blowing snow have eased. What is being called “The Blizzard of 2010” is now history, though it was certainly not a blizzard, by definition, everywhere. In  Boston, it was. Areas further south especially along the coast saw some mixing and rain, which cut down snow amounts, and obviously took away from true blizzard conditions. Snowfall amounts in Greater Boston were generally 10 to 19 inches, with the higher amounts of 18.2 inches and 19.2 inches reported at Boston and Saugus, respectively. Here in Woburn, I recorded 15.5 inches of snow, which melted down to 1.30 inch of precipitation.

Tuesday was a windy & cold but very bright & sunny day. This has set the stage for a stretch of quiet weather to close out 2010. The final 3 days of the calendar year will feature sun & clouds along with a trend toward milder temperatures. Thursday & Friday should see high temperatures exceeding 40. As we get to First Night, the temperature in Boston may still be near 40 early, coasting into the 30s later, but certainly not as cold as it can be and has been. The weather will be favorable with no rain or snow, and generally light wind.

The first day of 2011 on Saturday is expected to be mostly sunny & mild as a ridge of high pressure builds right over us. We could see a high temperature of 50 or even slightly over, despite snowcover, which tends to temper warmups.

The next chance of precipitation will come in the form of rain showers as a cold front crosses the region on Sunday.

Tomorrow, we’ll look into next week to see if the milder weather pattern will last, or is only temporary.

Enjoy these few days of more pleasant early winter weather! But be alert if you are out in the early morning hours for icy patches as melting snow refreezes overnight.

Late Night Update

Hi all! Just a quick update on the storm. The intensifying low pressure area responsible for the heavy snow & strong wind over most of eastern MA will be drifting northeastward, just southeast of Cape Cod through early Monday morning. The line of mixed precip (sleet & rain) that was along the coast almost to Boston but mainly over the South Shore has started to go back the other way and will make its way toward the Cape Cod Canal and eventually across Cape Cod as the precipitation tapers off during the early to mid morning.

The heaviest snow bands are in the 128 belt as we approach midnight. This will likely be the jackpot area with 16 to 19 inches in most of this region. Again, a few spot heavier amounts may occur but most places will be under 20 inches ranging down to around a foot. There has been somewhat less as you head west toward the CT River Valley, but other bands of heavier snow in the Worcester Hills & the Berkshires. Areas that have stayed all snow have seen a mostly dry, fluffy snow, lower in water content and easier to remove, though some significant drifting has occurred due to strong northeast to north winds.

Here in Woburn, after a lull in the snow during the 7pm hour, we’ve been experiencing moderate to heavy snow and occasional white-out conditions since about 8pm.

The heaviest snow will continue to fall overnight, tapering off shortly after dawn. Lingering snow will continue through the morning with a few flurries possible early in the afternoon Monday before it’s all over. The sky may even start to clear from the west toward sunset Monday as we dig out.

Even though the snow will be done by afternoon, expect some additional blowing & drifting snow due to strong wind gusts from the N to NW on Monday.

A blog entry later Monday will talk a little about snow amounts and other storm effects, and a look ahead to the final days of 2010.

Storm Update #2

The only change, and this doesn’t impact inland areas, is that the entire storm is trending a bit colder, which means there is less of a chance of any mix/rain getting involved unless you’re over far southeastern MA and especially the Cape & Islands. This is a drier, fluffier snow solution, and will allow most of the area to get 12-20 inches, with a slight risk of spotty heavier amounts. The storm is underway, obviously, and will peak during a 12-hour period starting about 7pm & ending about 7am, with the heaviest snow & strongest wind likely to come shortly after midnight. As stated earlier, some snow will linger through the day tomorrow, with small additional accumulation.

I hope everybody is safely where they need to be for the night. If you don’t have to travel tomorrow morning, it would be a good idea to stay put until the snow tapers and the road crews catch up. I, myself, am not so lucky. I have to be at work. Enjoy the storm everybody! Update coming later tonight…

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