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 note for readers in Aroostook County, ME: After the two to three feet of snow we've received, there is a bit more on the way for late Wednesday night, and a more significant round of snow...which may or may not mix with rain...late Thursday into Friday. This is going to be a very heavy, wet snow, and if it stays all snow, another foot is possible. If it mixes with rain, amounts would be limited. But regardless, this will add tremendous weight to the already heavy snow on our building rooftops. All flat roofs MUST be cleared off today or Wednesday, before this next round arrives, as many buildings would not be able to handle the stress of what will be a waterlogged 3-4 feet (or more) of snow from the two storms. Additionally, exhaust vents on the home should be cleared to avoid carbon monoxide poisoning. This is essential in the next two days.
For all of New England, the final week of 2005 will be warmer than normal, after a significantly colder than normal start to the month of December. 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. That doesn't mean it can't or won't snow in New England, it simply means we have a break in the deep cold with more of a tendency for rain/snow mixes in each event.
Residents of Northern Maine are digging out from a tremendous snowstorm that dropped between two and three feet of snow on Aroostook County from Sunday night through Monday night. Farther south, black ice was a problem all the way into Rhode Island and Cape Cod Tuesday morning, but will continue to melt off as a brisk northwest wind sloping down off of the mountains and hills, and ushering in drier air from Canada, will mean increasing sunshine for most of New England. Though the air moving in is dry, it's also cold, and highs will struggle to get much above freezing on average. This period of fair weather comes as New England falls sqaurely between storm centers, with another area of low pressure already moving through the Southern Plains by Tuesday afternoon and into the Lower Mississippi River Valley by evening. As the storm moves east of the Mississippi River Tuesday night, it will begin to tap moisture from the Gulf of Mexico, and the area of precipitation associated with the storm will blossom.
By Wednesday, the first surge of moisture associated with this storm will push northeast toward New England. The result will be a day that begins with sunshine, and is followed by thickening clouds during the afternoon. A weak disturbance at the jet stream level...combined with this surge of warmth and moisture...may allow for a few showers of rain and snow to break out from south to north during the afternoon and evening on Wednesday. But while some of this moisture breaks toward New England ahead of the storm center pulling into the Cleveland, OH, area, most of the energy and moisture will focus around a new storm center that will develop along the Mid-Atlantic coast by Thursday morning.
But the weather map by Wednesday night will be a bit more complex than just this one area of coastal low pressure. The initial, primary storm center will be weakening as it moves northeast over the Eatern Great Lakes, but will interact with a stationary front laid across Northern New England to usher precipitation into the North Country well before the coastal creature draws north. The result will be for precipitation to ride in just as warm air penetrates the releasing cold dome across Northern New England, and after a brief period of snow that's possible Wednesday night, precipitation should turn quickly to rain across even the Northern Mountains. The problem in these locales will be that while the air aloft is warm enough to support rain, the mountains will significantly slow the process of warm air coming in at ground level, and the result is likely to be between .15 and .30" of freezing rain ice accretion across Northern VT, NH and Western ME Wednesday night. After the passage of this weakening low pressure center, a break in the action will follow for the first half of Thursday, and it's during this time that warmer air will finally make it to the surface across the North Country. In Southern New England, it appears as though we'll be too far south to worry about this first round of precipitation, and by the time steady rains arrive from the northward moving coastal creature, temperatures would be warm enough everywhere for rain Thursday afternoon. 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 heavily at times Thursday evening and night through Central and Southern New England, with winds likely to kick up along the coastline and either side of an inch of precipitation. In Northern Maine, it is essential that we make preparations for additional snow and the potential of a mix with rain now, as mentioned at the start of this discussion.
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 may allow the storm to end as flurries even for Southern New England.
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.
By New Year's Day, this 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. But, time will tell.
Have a magnificent Tuesday.
Matt
Matt's Technical Meteorological Discussion: Updated Tuesday, December 27 at 2:35 PM
Winds will subside tonight and central/northern valleys decouple. Temps fall into single digits in those locales while else where light breeze keeps temps from tumbling below upper 10's most of rural southern NewEng, 20's urban areas and far Southern NewEng.
Start with sun Wed then increasing cirrus as soon as mid-morning thanks to moisture streaming north at 500 mb and above. Primary low pulls NE across Nrn OH and then vort shears out while moving across Nrn NewEng Wed ngt, but with enough cyclonic vorticity advection, moisture advection, and baroclinicity thanks to nearby stationary frontal boundary to create swath of relatively light precip. Problem is warm air has already returned by then at 850 and above, but will not be so quick to return to non north-south oriented valleys of the North. As a result, freezing rain is the likely scenario and NAM ptype algorithm picks up on this nicely. QPF between .10 and .30" and runs from Central VT to Lakes Region NH to Portland area, and points N. Remember that last time this was expected to happen, verification was that rain blossomed farther south as elevated convective elements in warm advection. That's entirely possible again with vort lobe actually moving over Southern NewEng, and feel it's wise to extend chance of precip into Southern NewEng overnight Wed ngt, though likely warm enough there for plain rain showers.
Break in the action for first half of Thu as primary low races NE of us and energy/moisture consolidates around coastal low developing off Mid-Atl coast. Rain develops late Thu assoc with this system, and it will be warm enough by that point for plain rain through almost all of NewEng. Aroostook County, ME, saw an incredible event yesterday and you have the potential for another incredible event, though not of the same magnitude with respect to snow, though perhaps with respect to human impact. Detailed this in the summary above, but we really have to be cognizant of roof failure potential in this area where 2-3 feet of snow that has fallen will be topped with likely another foot of heavy, wet pasty snow, or a mix of snow and rain. Either way, this poses a problem in these areas.
Friday wraparound snows are likely, and this storm truly will behave in a very similar manner to the last, though perhaps with everything displaced a bit farther north than last time given the farther north placement of the stationary front antecedent to the storm's arrival. Still, I'd expect ski country to receive a nice slug of fresh snow on Friday after pouting through rain Thursday night and Friday morning. Farther south, tough to say if we see the coating to 1" like we did last night in parts of Southern NewEng...will wait for guidance to resolve system a bit better. Regardless, event likely to drop either side of an inch of QPF many parts of Southern NewEng again.
Quick break Sat AM between systems before next system - with less moisture and no direct southern stream connection - moves in. Vort max with this one will be dampening but still impressive cyclonic vorticity advection that will crank out mixed precip later Sat and Sat night. Should be all snow central/northern areas where a couple of inches fall on New Year's Eve and farther south...more removed from the vorticity advection and in somewhat warmer low level air...expect a blend of rain and snow showers Thu eve/night to transition to snow showers but with only a little accumulation in some spots.
Regardless, the chilly air that settles in for New Year's Day will be installment #1. I fear that yesterday I was too hasty in my assessment of the overall pattern for the start of the New Year. That is, while I'd discussed the possibility for snow but an overall warmer than normal pattern, I was referencing the 850 mb temperature anomalies - all quite positive across North America. It's the little inconsistencies that get us here though. For example, there is a clear tendency of building surface high pressure into the northeast beginning with the shot on New Year's Day, and continuing through the first 7-10 days of January. This pattern...though in a regime of North American 850 mb warmth, and mid level warmth with anomalously high heights, for that matter, will still bring surface cold spilling into the Northeast...perhaps moreso than elsewhere in the contiguous US. Now comes the importance of the 850 warmth. Imagine a corner of the continent (the Northeast in this case) where low level cold air rules the roost. 850 mb temperature anomalies are close to or only just barely above normal at the end of December in this corner of the nation, but the corner is surrounded by anomalous warmth. All the while, an active jet stream in both the southern and northern streams is present. What does that leave you with? Overrunning like crazy. Every event is overrunning, every event is carrying anomalously warm air into a cold low level airmass. I can't believe I missed this yesterday, but it was like a revelation today. Check out the maps I've included here of 850 mb temp anomalies for Jan 1, 3 and 5. In the first two, near normal 850 temps are present over only NewEng. In the final, warm advection has occurred. Basic synoptics tells us that in order to have changes of this magnitude...and with all of the overrunning that will occur...we have to crank out plenty of precip in the process unless something out of the ordinary should occur. The end game on this is that the first 10 days of Janary will feature a pattern that doesn't just favor phased systems like we've seen, but strong ones. Systems strong enough to plow warm air into a shallow cold arctic dome and then overcome it. The bottom line on this is that...if my more in-depth read on this today is accurate...we're looking at what may be a very snowy beginning to the month of January and for 2006 - and perhaps with quite a bang - in the first week. Now, let's not go drawing the accumulation maps yet, as this is a theory, but it's one that is based on sound and reasonable synoptics, and I know you and I will both be pouring over the data to see how this is looking in the next few days.
Matt
