Welcome to the weather blog - a regular Monday through Friday discussion of the weather! You'll find a quick weather synopsis and 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 Quick Weather Synopsis (New!): A strong storm winding up in Eastern Canada is feeding cold air around its belly, into New England. Southwest winds will gust as high as 40-45 mph on Monday, ushering in this chilly air and holding temperatures in the 30's for most spots. Scattered snow showers and some heavier squalls will continue to fly through the day, hitting some communities hard with briefly heavy snow, while sparing others entirely. Especially vulnerable will be the mountainous and hilly terrain. Otherwise, more clouds than sun prevail. Breezes stay active overnight Monday night and with temperatures falling into the 20's, wind chill values will be in the teens. Tuesday brings more clouds than sun early, then increasing sunshine, while scattered snow showers and squalls continue in the mountains. Expect a dry day Wednesday, though colder temperatures will be with us through the week. The active storm track stays south of New England, though we may be grazed with the northern edge of a snow shield on Thursday morning. Expect the cold to stick around for weeks - winter has returned to New England.
General Weather Summary: The same storm that pounded parts of Michigan with wind-driven snow on Saturday has continued to wind up as it migrates north into Eastern Canada. The result has been for the counter-clockwise flow of air around this system to drag cold air out of Canada and carry it into the Great Lakes and the Northern Tier of the United States. Through the day on Monday, active southwest winds (normally a warm wind direction!) will yank this cold air out of the Great Lakes and Ohio Valley, and drag it into New England.
In the transition, snow squalls will continue to fire up across our six-state region under a windy blend of more clouds than sun. Bundles of energy interacting with near-surface moisture will wring out flurries, snow showers, and heftier, wind-blown snow squalls that can quickly coat roadways with snow and ice, and reduce visibility dramatically. Otherwise, new, chilly Canadian air streaming in on 40-45 mph wind gusts at times, will mark the beginning of the much anticipated return to wintry weather you and I have discussed here together over the past several weeks, slated to be in place by mid-month. After Monday's blustery near-40 degree readings in some areas, the remainder of the week will bring a noticeably colder and wintry feel, as we dig in for what will be a few if not several weeks of winter's return.
With such a large storm wound up just to our north in Eastern Canada, a fast flow of air will be present not only here on the ground, but also high in the sky, at the jet stream level where storms are steered and that fast corridor of winds acts as a thermostat for the atmosphere, separating cold air to the north from warm air to the south. This corridor of jet stream winds has dipped south of New England, and that means the active storm track will also be south of our region - through the Southeastern U.S. and off the Mid-Atlantic coast - at least for the time being. The result is a continued feed of cold and relatively dry air, interrupted only by spokes of energy rotating around the Canadian storm, picking up moistue off of the Great Lakes, and cranking out snow flurries and squalls through Tuesday morning, especially in the mountainous and hilly terrain. Expect drier air to assist in brightening the skies Tuesday, as we transition from more clouds than sun, to just the opposite by day's end.
Wednesday should be a dry but chilly day for just about all of New England with a break between energetic disturbances aloft, and a continued storm path to the south of New England. Meawhile, another storm will be taking shape in this active track across the Mississippi River Valley later Wednesday and toward the Mid-Atlantic coast Wednesday night. While it certainly appears from all guidance that this next disturbance should also stay south of New England, there are some subtle hints that the moisture associated with it may try to expand farther northward up the East Coast sometime on Thursday - likely early in the day if it were to occur at all - and this potential needs to be monitored. As a result, I've felt it wisest to put a chance of snow in the forecast, and we can of course fine tune this as we near it, and drop it from the forecast if appropriate.
Cold air will continue to pour into New England through next weekend, with an active storm path orienting itself on a slightly more south to north axis, which will keep us on our toes for snow threats through the rest of the month. I truly believe the bottom line here is that this week marks the first week in our transition to the active winter weather you and I have been ready for in these discussions for the past few weeks.
Here's to a great Monday!
Matt
Matt's Technical Meteorological Discussion: Updated Monday, February 6 at 2:15 PM
Multiple shortwaves combined with low level convergence zones associated with attendant surface troughs and steep low to mid level lapse rates allowing for widespread snow showers. Heavier snow squalls embedded from time to time in this environment and dropping quick half inch to inch of snow - into surface temps that are in the mid to upper 30's and cold enough for some icing of roadways in heavier squalls.
Atmosphere stays mixed as breezes stay active Mon Ngt which introduces wind chill into fcst overnight. Squalls continue - primarily in upslope favored regions where topography aids in forcing combined with lingering moderate to steep lapse rates as -30 C 500 mb temp cold pool rides over Nrn VT/NH/ME. A few fresh inches for the higher terrain of the Greens, Whites and NW ME should be the result.
Another windy day on Tue as well mixed atmosphere combines with strong - though weakening - pressure gradient force. Mid level temps warm considerably during the day and while day should begin with convective activity of at least plenty of clouds and some orographically favored snow showers in cyclonic flow that will be somewhat lake enhanced, esp in Western NewEng, would expect this to squash out as drier and more stable atmosphere takes hold.
Beyond...remember that last week, together we left off acknowledging upper level flow would be too confluent to allow today's shortwave to possibly come this far north (it's producing the precip across the SE US right now) but that there was more concern for the Tue shortwave. Looking at progs now, it still appears as though the flow is too confluent, and the jet stream too far south on Tue for this next shortwave to come anywhere in our neighborhood. So, given the slower retreat of the vortex to our north, does this mean we give up on our thoughts for this circulation from last week? Not quite - or perhaps more accurately, not yet. Even just a quick and dirty examination of the upper level plots for this week indicate there are TONS of shortwaves - or at least vorticity lobes sheared or otherwise - embedded in the flow. Additionally, rising heights over the northeast the next couple of days will allow the jet stream winds to gradually ride farther north, which means we need to stay on guard for each shortwave embedded in the flow, especially considering a shortwave passing south of NewEng, if it could get its act together with a low or mid level circulation, would direct a moist easterly flow our way. But...it's important to distinguish between "wishcasting" - done when someone either wants a solution to verify and comes up with all the reasons why it could - and forecasting - putting out the best possible representation of what may transpire.
So, let's stick to the forecasting, and stick to the facts: There will be four shortwaves in particular to be watched over the next 6 days, not including the Tuesday wave that stays south of NewEng. The first rides through the flow Wednesday night into Thursday morning, followed immediately by a strong northern stream shortwave and associated trough axis Thursday afternoon and evening. This combo needs to be watched for possible trouble. The next comes through Friday evening and night. The fourth comes through Saturday evening or perhaps as late as Sunday dependent upon how it evolves.
At first glance, the Wed Ngt/Thu AM shortwave looks innocuous, esp considering the 250 mb wind forecast on the NAM is actually shifting S during that period. It's always been the little inconsistencies, however, that I feel can bring the most interesting surprises. One of these little inconsistencies is the forecast by both the NAM and the GFS to carry moisture farther northward (much farther north) than the precip shield, and bring it over at least part of Southern NewEng on Thu. This northward push is really a cursory interaction with the incoming northern stream shortwave trough that is slated to swing thru Thu Eve, but the problem is an insistence to pull 500 mb and perhaps even 700 mb moisture northward well ahead of this northern stream trough axis Thu AM as the southern stream wave rides south. Additionally, the GFS is creating a farther north, secondary jet streak aloft, which takes a position much more favorable to carry a northern shield of snow into parts of Southern NewEng. The tricky part here is how to convey this to the public. I HAVE put snow in the forecast for Thu in association with this system, and I've made sure to explain the tentative nature of it - watching the northern shield of snow from a storm to our south. Meteorologically, though, I think these few inconsistent points in the guidance are important to keep an eye on. I based my forecast on the 00Z Mon runs, and it's interesting to notice the 12Z Mon runs are trending even more in this direction. So, we'll wait and see on this one.
Next in line is a shortwave slated for passage Fri eve. Given the tendency of models to inaccurately estimate shortwave timing in a fast flow, this thing could come thru anytime between Fri daylight and Sat AM, though typical model error is to bring it east too slowly in fast flow, so earlier may be better. Regardless, this shortwave scoots south of NewEng and is likely to throw warm advection out ahead of it, so we're likely to crank out a period of snow in isentropic lift later Fri or Fri ngt with its passage. Arguing against this is the sheared nature of the vort in the progs, but if the jet stream forecasts are anywhere close to accurate, this thing should come close enough to give us at least a shot.
Next one in line would extrapolate through later Saturday given current forecasts, though one interesting feature to the upper level flow at this period is the multitude of shortwaves behind the leading one, helping to lower heights all the way to the Intermountain Region across the Northern Tier of the US, and thereby allowing the longwave trof to have a somewhat positively tilted orientation. With weaker flow developing on the west side of the trof base, it's entirely possible for a situation to develop in which shortwaves dropping south out of Canada are coming in faster that shortwaves are ejecting out the eastern base of the trough. The result here would be a merger of several vorticity maximums, yielding a slower but stronger solution as everything shifts east this weekend. It's a trend to pay close attention to in the guidance over the next few days to see if trends head in this direction. First product to jump on this bandwagon has been the 00Z ECMWF, whose solution is not as far-fetched as one may think given the pattern described above, but it's also simply a representation of what *could* result from this setup.
Looking even farther out, I'm going to save my fingers the typing on how and why the pattern will evolve as it will since it's been hashed out here the past couple of weeks (if you're new to reading though, feel free to peruse the archives at left), but the bottom line is that the longwave pattern transition is underway and the gears are in motion. Cross polar flow prevails the next couple of weeks thanks to a tremendous ridge cranking up over Western North America, the Eastern Pacific and, eventually, over the Aleutian Islands. Remember that it's this Alaskan and Aleutian cold we've been eyeing for almost two months together in these discussions, now, realizing that cold, though it correlates to Northeast and Eastern US warmth, would be money in the bank after the expected major pattern reshuffling as the upper low on the other side of the globe broke down. But get this...I don't think it stops there.
Siberian cold continues to build and over the next several days will shift east to the coastlines of Russia along the Northwestern Pacific Ocean. This cold shifts east - taking with it plentiful amounts of energy from the swirling vortices in this region - as the ridging established over the Western US and Western Canada retrogrades and explodes over the Aleutians and Alaska. This ends up being critical to the way February unfolds, not only for the Northeast but for the country as a whole. Reason being, the increasing baroclinicity between built up and deep cold over Eastern Asia with a pounding and monstrous ridge over the Eastern Pacific results in phenomenally fast flow from south to north around the west side of Alaska. Multiple strong vorticity maximums eject from the East Asian upper low and are directed around the crest of the ridge, picking up serious surface cold from the North Pole and then carrying southward lock, stock and barrell in the establishing cross polar flow. The result should be a continuation of the trough "development" over the Great Lakes and much of the Northern Tier of the US that we looked at a couple of weeks ago, as the trough continues to truly develop from the bottom up with low level cold the first to arrive - and this is already playing out nicely as each successive 500 mb analysis indicates a deepening upper low over Eastern Canada - a pattern that will first favor eastward ejecting shortwaves from the Intermountain Region south of NewEng with strengthening circulations capable of delivering shots of significant snow in easterly flow as they come by (harkening back to earlier in the discussion regarding upcoming potential) and eventually evolving into a pattern favoring more focus upon the baroclinic zone along the Eastern Seaboard. The end result is to pour most of the cold out of Eastern Asia and into the U.S. by the third week in February, and as the northern periphery of the Eastern Pacific ridge breaks down, the troffing in the US becomes more broad, and cold air truly invades almost all of the nation by this time period.
That's all for today.
Matt
