Beyond Tuesday

1220am

Now that we covered Tuesday’s winter storm, let’s look a little beyond that.

Wednesday will feature lots of clouds, but also some breaking of those clouds. There may also be some scattered rain & snow showers as lingering energy passes across the area. It will be relatively “mild” as compared to recently, with a high temperature in the upper 30s to perhaps 40 in a few areas, before it starts to cool down later in the day, along with increasing northwest winds as low pressure finally pulls away to the northeast of the region.

Thursday will be a bright, cold day, with  a high temperature near or a little below freezing.  This will set the stage for the next storm threat, which the computer models have had trouble timing during the past few days. The best guess now suggests that this system will arrive during Friday morning, and with plenty of cold air in place will be in the form of snow. How much snow will be determined by the exact track and speed of low pressure, which will pass south of New England. Early indications are for a decent shot at a moderate amount of snow from this storm system.

Behind the Friday storm threat lurks the coldest air of the winter so far, and that will be making a weekend visit, along with at least one day of gusty wind to make it feel even colder (Saturday).

Tuesday Winter Storm

1030pm

Good evening everyone! Sorry this is being posted later than I wanted. But a busy day will do that…

We have yet another bout of winter weather on the doorstep, moving in from the southwest for Tuesday. This storm, though not nearly as powerful and heavy precipitation-wise as the last, is slated to bring more of a variety of precipitation over a larger area. Whereas the last storm’s rainfall was confined mainly to the immediate coast and Cape Cod, this one will send a sleet/freezing rain/rain swath over a fairly large area of eastern MA and coastal NH.

Instead of getting into technical aspects of the storm, all that really needs to be said is that this particular setup will allow warmer air in above us, resulting in the mix and change in many areas, after starting as snow. The surface remains very cold thanks to a cold airmass in place and a deep snowcover from the recent storm. This results in a rather messy setup.

What to expect, and when…

This storm should start as snow everywhere in eastern MA and southern NH. The snow area is expected to advance north across the region during the morning, starting around 6am south of Boston and by 8am to the north, lastly in southern NH, and of course + or – about an hour either side of these times. The amount of snow that falls will depend on how quickly an area of moderate precipitation moves up into the cold air in place, while it is still cold enough above us to support snow. My best guess for snow before any mix/change occurs is around 1 inch to  locally 2 inches along the immediate coast, including the city of Boston, 2 to 4 inches just inland from here including the 128 belt, 3 to 6 inches from just outside 128 into the 495 belt, and 4 to 8 inches northwest of here in northwestern Middlesex County, southern NH away from the coast, and Worcester County.  There is an outside chance of an isolated heavier snow amount somewhere in the hills of Worcester County to nearby southwestern NH. Some selected cities and towns and what I expect their snowfall to be, plus or minus 1 inch either side (and if you live in one of these places let me know what you get please!)…

Boston MA: 2″

Woburn MA: 4″

Waltham MA: 3″

Londonderry NH: 6″

Nashua NH: 6″

Chelmsford MA: 6″

Worcester MA: 5″

Fitchburg MA: 7″

Milford MA: 3″

Hampton NH: 3″

If you want a number for your city or town, comment here and I’ll give you my best guess.

The snow will be the least of the problems from this storm for some people. Rain will become an issue for some, due to potential localized flooding in poor drainage areas if it should be heavy enough, and also the issue of snow/rain weight on flat roofs. Icing will be the other story, and trying to pinpoint the area of most significant icing (that is up to 1/2 inch or slightly more of ice buildup from freezing rain) will prove very difficult.

As the warmer air comes in aloft and starts to put an end to the snow from south to north, it will flip to sleet for a time (frozen raindrops, or ice pellets), which generally do not cause major problems) then plain rain closer to the coast and south of Boston where the surface temperature is above freezing, but freezing rain (or rain that comes down and freezes to a glaze of ice upon contact with the ground, or the snowcover). The glazing takes place in areas where the surface temperature is at or below freezing. I’m still not sure where this changeover line is going to make it to. A best guess at the moment is that it will make it into coastal NH and most areas along and southeast of Route 95 in MA fairly easily. The areas near 95 will probably see a period of sleet & freezing rain with some minimal glazing before it goes to plain rain during the afternoon Tuesday. As you go further west and north, the changeover will occur later and the sleet to freezing rain will occur longer. As I see it, the most likely areas to see icing of 1/4 to 1/2 inch or slightly more will run from the MA/NH border through Lowell/Chelmsford, southwestward through the central part of Middlesex County including the Concord area and further southwest from here down toward Worcester. This significant icing belt may be only about 10 miles wide, so we’ll have to watch radar and surface observations to see where it sets up. North and west of this area, precipitation will remain mostly snow & sleet, but may turn to freezing rain for a brief time.

The main precipitation area should begin to taper off and exit from southwest to northeast during Tuesday night, and be all but over by midnight. Temperatures over areas that get ice & snow will remain fairly chilly and untreated surfaces will be slippery throughout the night. Further south and east, areas that get less ice and more rain may develop some slick spots as temperatures fall to near or slightly below freezing, especially if there are any breaks in the clouds, which would allow it to cool more quickly.

Caution should be used in all areas for any travel Wednesday morning.

Quick 7-day Forecast for Boston Area

215am Monday January 17 2011

Today… Bright sunshine, fading at the end of the day as high clouds show up in the southwestern sky. Very cold with highest temperatures from the upper 10s to very low 20s. Light winds.

Tonight… Mostly cloudy. Temperature holding near 20 early then rising through the 20s. Light east wind.

Tuesday… Overcast. Snow developing from south to north between sunrise and 900am, accumulating from a coating to 2 inches in the Boston area except 2 to 4 inches outside Route 128 in areas north of the Mass Pike and possibly 4 to 6 inches outside Route 495 mainly north of the Mass Pike. Snow changing to sleet & rain from southeast to northwest across the region midday through afternoon, but a period of freezing rain is possible especially in the Merrimack & Nashoba Valleys. Highs will climb into the 30s but may remain right near the freezing mark in valley areas northwest of Boston.

Tuesday night… Overcast with periods of rain. Icing should come to an end where it occurs as temperatures range from the middle to upper 30s.

Wednesday… Mostly cloudy with some lingering rain showers or drizzle in the morning. Becoming partly sunny in the afternoon with increasing northwest winds. High temperatures right around 40 through the morning, then cooling through the 30s during the afternoon.

Thursday… Mostly sunny & chilly with a high near 30.

Friday… Chance of light snow or flurries in the morning followed by clearing. High in the upper 20s.

Saturday… Mostly sunny. High in the upper 20s.

Sunday… Chance of snow. High in the middle 20s.

Half Way

1010am

We have reached the half way point of meteorological winter (December-February). Sometimes the whole concept of meteorological winter is rather silly, given how many of our larger snowstorms and some significant cold outbreaks have occurred in March and even sometimes April. But there are the limitations of definition. Weather doesn’t really care about such limitations.

The weather continues to prove my long range winter forecast pretty much wrong this season. Everything has been happening 2 to 4 weeks later than I expected, with persistent blocking being the main reason. Only this coming week is going to resemble the type of weather I expected to dominate January, that is, storms of mixed or transitioning precipitation preceeded & followed by cold. Such a mixed storm is expected on Tuesday, preceeded by cold Monday & followed by late-week cold again. In addition, we’ll be watching for one more storm threat around Friday, but there’s about a 50/50 chance of this system being too far east to have any significant impact on New England.

After the passage of a weak Alberta Clipper system which brought some light snow shower activity, we’ll have a bright & cold Sunday, but otherwise fine to run those last minute snack errands before the Patriots & Jets kick off at 430pm. For those going to the game, it will be quite cold, with a game time temperature in the middle 20s, falling into the upper teens by game’s end. But with a clear sky above and diminishing west winds, it will not be as harsh as it has been during some playoff games.

Looking ahead…

Monday (MLK Jr Day) which some of you have off (I don’t) will feature bright sun & very cold air with a high temp barely reaching 20!

A storm system moving through on Tuesday will bring snow that will then likely change to rain. However, a period of icing is possible especially inland and over valley areas where cold air remains trapped.

The storm will be moving out on Wednesday. There are some questions about some lingering moisture moving up from the southwest to produce additional precipitation, which could be in the form of snow as colder air moves back in. At the moment, I don’t expect this to be a big deal in terms of snow amounts, but it could make things slippery. By the end of the day, wind & cold will likely become the main story.

Thursday looks like a bright but very cold day, and by Friday we may be dealing with the next storm threat. Right now, most indications are that we will get a glancing blow from an offshore storm, with a threat of some snow. But as always, this far out there are too many uncertainties and this potential will be monitored.

Looking way out to next weekend, there are signs of some very cold weather, perhaps the coldest of the winter so far.

Short & Sweet … More later…

355pm

Hi all!

Well I underforecast snow amounts, obviously, in a good part of inland locations. My coastal forecast was better this time. I wish I had bought the precipitation being cranked out by my favorite forecasting model, but I thought it was overdone, and it turned out for the 2nd time in a row I made the same mistake. I have learned my lesson. Also, the storm was in quicker than I thought, by about 2 hours. So if anybody was inconvenienced by my info that didn’t work out, SORRY! 🙂 The main thing is, I hope everybody is safe!

I am running out for a while, lots of cleanup and some driving to do, but I will be back later with some more details on what happened, and what’s to come in the next several days. Is there another storm on the horizon? You’ll have to wait to see. 🙂

Quick Update!

For the moment I’m going to lean toward the lower side of my totals, that is, closer to 10 versus 16. Snow has come in earlier than expected, but I’m also observing trends that make me a bit nervous. Temperatures right along the coast from Cape Cod all the way up through Boston to Gloucester as of 1am are 36 to 40 with winds straight out of the east. This is being fueled by the relatively mild ocean water. No doubt later in the storm as the low pressure area wraps up, colder air will push back into these areas, but this boundary that seems to be setting up in that area (a coastal front) may limit snow totals near and just east of it.

For the most part the forecast I made is still something I’m comfortable with, but watch these areas near the coast early in the storm for wetter snow and less accumulation. One thing we really have to watch for is that sometimes the low pressure areas can try to track along these coastal fronts, and this could result in a slightly more westward shift to the track. That may allow a dry slot to work in from the south and southeast, and could shut down the snow earlier than expected. Another thing to watch for that could limit totals.

145am Wednesday 1-12-2011

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.

Your no-hype southeastern New England weather blog!