Welcome to the weather blog - a regular Monday through Friday discussion of the weather! You'll find a general non-technical weather summary below, and when available (most days) a detailed technical meteorological discussion will follow. If no technical discussion is available when you check in during the morning, check back later as it often comes after the Weather Summary - I try to indicate at the end of the general weather summary when/if a technical discussion is coming. My email is contact@mattnoyes.net. While the discussions usually will only come on days I'm working, I'll occasionally issue special updates when the weather warrants. This blog is for you, so I hope you enjoy it! -Matt Noyes
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Matt's Weather Summary: An important reminder from yesterday's discussion for readers in Aroostook County, ME: Another significant winter storm Thursday into Friday will add tremendous weight to the already heavy snow on our building rooftops. All flat roofs MUST be cleared off today, before this next round arrives, as many buildings would not be able to handle the stress of what will be a waterlogged snowpack from the two storms. Additionally, exhaust vents on the home should be cleared to avoid carbon monoxide poisoning. This is essential to complete, as today is your final window of opportunity. Most of us in Aroostook County have generators, and we should be sure to have them ready to go for what may be an extended time without power.
For all of New England, the mild pattern rolls on to finish 2005, and the propensity for coastal storms continues, as another storm will run up the coast and directly over Southeastern New England Thursday Night. A large reason for this is a ridge - or rise - in the jet stream winds aloft allowing for warmer than normal temperatures to build in both the U.S. and Canadian Rockies, and this effectively cuts off our supply of deep cold air in the immediate term, but keeps a trough, or dip in the jet stream here in the east, which keeps energetic disturbances dropping into the Midwest, but turns storm-steering winds to blow from south to north along the east coast. These southerly winds aloft bring repeated shots of copious moisture and slugs of warm air out of the Gulf of Mexico.
The latest energetic disturbance is evident on satellite imagery Wednesday morning, pinwheeling across the Midwestern U.S. and into the Ohio Valley. This energetic storm has been relatively devoid of precipitation on its trek across the nation, but today will encounter a feed of warm and moist air spilling northward out of the Gulf of Mexico, and the precipitation shield associated with this storm will blossom through the day. A piece of energy from this storm will eject northeast toward New England later Wednesday, and the result will be for sunny skies to give way to increasing cirrus clouds that will add a milky appearance to our Wednesday afternoon sky as moisture races in ahead of this distubance.
Expect showers to move into Northern New England Wednesday evening, and with the sun setting and rain just moving in, many areas will experience freezing rain during the overnight. Some communities in deeper valleys, such as the Champlain Valley and Upper Valley, may escape by holding temperatures just above freezing through most of the night, but many other areas of Northern New England will turn cold enough for ice to accrete on untreated surfaces Wednesday night, with only about 1/10 of an inch of ice expected. Closer to the Canadian border, however, amounts will approach 1/4 of an inch of ice by Thursday morning, and that's just enough to place stress on tree brances and powerlines, and isolated power outages are possible in the Northeast Kingdom of VT and extreme northern NH and Western ME. Northern Maine will receive one to three inches of snow before a changeover to sleet early Thursday morning.
After the passage of this weakening disturbance Thursday morning, our attention will turn to the Mid-Atlantic coast as warm air streams northward into most of New England and a storm center takes shape along the coast of Delaware. This coastal storm will be just the next in what has been a series of storms raking the Eastern Seaboard, and I'd expect rain to fall steadily beginning Thursday morning, then heavily at times Thursday afternoon through evening in Central and Southern New England, with winds likely to kick up along the coastline and either side of an inch of precipitation. While most of the North Country will be warm enough for plain rain by the time this coastal storm moves in, Northern Maine should prepare for a significant ice storm, with enough warm air aloft for freezing rain to fall through Thursday afternoon and night, accumulating between 1/2 and 3/4 inch of ice before changing back over to snow Friday morning, especially from Caribou north and west through the St. John Valley and up to Fort Kent. While this doesn't sound like much, considering only 1/4 inch of ice can cause power lines and trees to collapse, this will be a signficant ice storm if it shapes up as it's appearing right now. While things can change - only a change of a few degrees in temperature aloft will mean slippery but comparitively harmless sleet - I would strongly advise that residents of Northern Maine not only clear off rooftops to avoid building collapses today, but also ensure that you are prepared for an extended period of time without power, especially north of Caribou and through the St. John Valley. Have the generator ready to run for an extended period of time as several days of power outages will be possible in these areas, and have the snowmobile at the ready with extra gas handy, as trees and powerlines may fall across roadways. Most of us in Northern Maine have the necessary tools to handle a storm of this nature, but ammenities may be lost for an extended period of time.
By Friday, this storm pulls northeast of New England, but like its predecessor earlier in the week, the tendency will be for a band of precipitation to wrap around the back side - or western periphery - of the storm, and with the counter-clockwise wind flow around the storm pulling down cold air, this will likely be a band of southward migrating snow. The result should be similar to our previous storm, as well, dropping a fresh accumulation onto Northern New England as the storm ends, and tugging down a shot of chilly air on Friday that will bring falling temperatures Friday afternoon after a relatively mild start.
By Saturday, our very active weather pattern continues. With the next storm not as eager to dip southward and ride up the coastline, there will be less moisture involved, but that also means we'll hold onto more cold air across New England. After morning sunshine, clouds will thicken quickly Saturday afternoon, with a blend of rain and snow showers likely to develop in Southern New England by New Year's Eve, and snow showers developing in Central and Northern areas and a couple of inches of accumulation possible overnight Saturday night in these central and northern locales. Should this disturbance ride in just a bit farther south, steady accumulating snow would be possible into parts of Southern New England on New Year's Eve, as well, so this is a system you'll be hearing more about from me.
By New Year's Day, this latest storm pulls away and will leave New England in a windy and chilly pattern. And could it be that nature will use our new month to turn over a new and colder leaf? It does appear as though the colder pattern I'd expected to come charging in like a lion this week, will instead set in through installments, with the first arriving for New Year's Day. With the weather pattern still favoring coastal storms, this will increase the likelihood of snowstorms for the first week of January, with the chances of a large winter storm highest during the first 5 days of January.
Enjoy your Wednesday.
Matt
Matt's Technical Meteorological Discussion: Updated Wednesday, December 28 at 2:00 PM
Cirrus clouds to continue riding in and deck lowers/thickens late day as isentropic lift increases ahead of vort lobe ejected from main upper low and interacting with rippling stationary frontal boundary. Still expecting light freezing rain tonight in Northern NewEng. Only about .10" most areas, and daytime highs will be warm enough that this will be a very borderline event - and perhaps a non-event of regular rain showers - for the lower elevations like the Upper Valley and Champlain Valley. Elsewhere in the north, clouds should not completely offset cooling of dry air and light winds that will allow temps to drop below freezing. Southern NewEng stays above 32 most areas...though a few pockets of subfreezing temps aren't impossible in valleys through Northern Worcester County and Northern Franklin County, MA, though amounts will be quite light in these areas.
Slippery start across affected northern areas Thu AM, then a break in the action for the north. Looks like rain makes it into Southern NewEng along developing coastal/warm front during the morning, either side of sunrise, and from that point on, rain falls heavily at times into the eve for Southern NewEng...and into the night in ME. Most intense upward vertical motion (UVM) from the guidance comes during the morning on the nose of the 850 mb low level jet where speed and some directional convergence occurs. That being said, UVM is likely a bit overestimated here and the heaviest rainfall should come during the afternoon and early evening as the low level circulation moves overhead, and the most significant warm advection occurs ahead of vort lobe that swings south to north by Cape Cod and into Maine coast by Thu Ngt.
All areas warm enough for plain rain in NewEng except Aroostook County, ME. As outlined in the weather summary, potential is there for a significant and life-threatening icing event, but borderline conditions for the biggest cities in the county. Presque Isle...judging by surface temp progs and MOS guidance alike...appears likely to change to rain for most of the event during the day on Thursday. In favor of this is the fact that winds turn SE here, but against it is the fresh and deep snowpack that will be unwilling to let much warm air in. My thinking at this point is to retard the changeover from freezing rain to rain longer than the models would indicate, but before the slug of heaviest precip spreads in Thu late afternoon. Of course, the second problem here is that winds go N and NNE Thu Ngt and this will drain cold back in, so some icing will occur even in PQI, and depending on how soon the change back to freezing rain occurs, over half an inch of precip still is left to fall overnight once the winds go northerly. Farther north, CAR has a better chance of seeing around half an inch of ice, and the best chance for significant icing which may produce as much as .75" ice accumulation is north and west of Caribou in the St. John Valley and farther north and west through Fort Kent. In these areas I am quite concerned about power outages that will last for several days if everything shapes up as it's looking, and I'm continuing to express my concerns for roof collapses.
By Friday, the cold air is slow to advect in through the low levels and this means by the time the profile turns cold enough for snow, the only places left ot accumulate will be the mountains of Vermont, NH and ME where upslope flow can pile on a few inches. Elsewhere, looks like most of the moisture has departed.
Saturday's system still looks impressive with regard to the vorticity advection associated with the shortwave as it ripples directly over NewEng. Additionally, the vort track is coming in just a bit farther south with each successive run. The GFS really picked up on this system in the 00Z run, but I think it's 12Z run is closer to reality. The NAM goes out only thru 00Z Sun and is too dry in NewEng even through that time period, I would think...but it is firing up the precip along the Mid-Atlantic so it's picking up on the moisture connection. In fact, 850 mb Theta-E suggests warm and moist advection already underway for sct rain and snow showers Sat afternoon, then a more widespread snow Sat night...with QPF amounts increasing the farther east one goes as the low level circulation works at getting its act together.
I've gone much below MOS for Sunday...I think the guidance is blind to shallow cold dome sliding north with higher pressure building south from Eastern Canada.
Next week should be interesting...still looks like a good chance of a decent storm inside the first 5 days of the month for the reasons laid out in yesterday's techie discussion.
That's all for today.
Matt
