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!): Morning clouds and Cape Ann, Cape Cod/Island flurries will continue to gradually give way to breaks of sunshine with a light wind across New England for our Thursday. Late Thursday afternoon and Thursday evening, an arctic cold front will push south out of Canada, delivering a shot of snow squalls to the mountains of Northern and Western New England Thursday evening, and migrating across most of the remainder of Northern New England - from most of Vermont to the White Mountains to points north of Augusta - Thursday Night with a quick 1"-2" with higher amounts in the mountainous terrain. A series of energetic disturbances zipping through the Northeast on Friday will keep mostly cloudy skies and a few flurries in the forecast, with a chance of steady light snow dropping an inch or two in some areas Friday Night. Saturday starts cloudy but quiet in most areas, though a storm center taking shape along the Gulf of Mexico coastline will turn north up the Eastern Seaboard and spread light snow into New England late in the day. By Saturday night, this storm will charge northeast, delivering a blow of snow, heavy at times to most of New England Saturday sunset to Sunday morning with over a foot a distinct possibility for parts of interior New England depending on how things play out, lesser amounts at the immediate coast (perhaps) and a rain/snow mix with lesser accumulations on Cape Cod. Windy and cold after the departing snow on Sunday. -Matt
General Weather Summary:
Late Afternoon Update: I've seen enough for this upcoming Saturday storm to warrant 6" amounts all the way from Central VT/NH/ME southward, pending a dramatic shift to a more progressive solution, which is still possible but looking less likely. Timing will be light snow developing Saturday evening and becoming heavier Saturday evening after sunset. Snow falls heavily Saturday night into early Sunday morning as storm center moves over Nantucket and Chatham - this means if all comes together as it's currently looking (and do remember from 48 hours out, things can change) a foot or more of snow possible through the interior of Southern New England, 10" or so closer to the coast with less possible at extreme coastlines where onshore flow may warm temps a bit, rain/snow mix at the Cape limiting amounts, and only a gradual drop off north into Northern NewEng. More on this tomorrow. -Matt
Previous: The current weather pattern across the nation is one that features plenty of energy, but very little moisture. This type of a pattern can yield major storms when moisture is introduced, and there are some indications this may be the case by this upcoming weekend, though this is certainly not set in stone. There is plenty more to share than can be expressed in a two minute television broadcast, and you and I will examine some of these additional factors for consideration in this discussion today.
First of all, the overall jet stream flow - the pattern of the fast river of air aloft that steers our storm systems and acts as a thermostat for the atmosphere, separating cold air to the north from warm air to the south - will be changing over the next few days. The first change is already underway, across the Western U.S. where the jet stream is rising northward rapidly, allowing a strong and mild area of high pressure to build along the West Coast and Eastern Pacific. In the atmosphere, a major change to the weather pattern in one part of the globe often leads to major changes in the other, and the result of a rapidly building ridge in the Western U.S. is often a strengthening trough - favorable for stormy weather - in the east.
Certainly we've already seen the results of this trough to a large extent, with cold air maintaining its hold on New England through the week, and another cold day expected on Thursday with morning clouds and flurries over Cape Cod, the Islands and outer Cape Ann, gradually giving way to increasing breaks of sunshine and light winds. Aloft, and approaching from the northwest, a strong upper level disturbance is heading directly for New England, and is dragging yet more cold air southward out of Canada. The leading edge to this reinforcing shot of cold air is evident at the surface as an arctic cold front, which will carry snow showers and heavier squalls into the mountains and hills of Northern and Western New England late Thursday afternoon, and especially Thursday evening and night. Some of these squalls will pack enough of a punch to reduce visibility dramatically, slicken roadways, and will drop a general 1"-2" across most of Vermont, the White Mountains of NH, and most of Maine north of Augusta. Locally higher amounts will be found in the higher terrain. For the remainder of New England, northwest winds sloping down the mountains and hills should help to dry the air enough to squash most of these squalls as they move southward, leaving only some Thursday night flurries for most of Central and Southern New England.
By Friday, another energetic disturbance in the upper levels of the atmosphere will move toward New England, this time coming from the nation's midsection, and ushering slightly warmer air into our six-state region. The clash of airmasses between Thursday night's reinforcing cold air, and this new approaching warm air aloft, will create lots of clouds for most communities on Friday. With very little moisture near the ground, however, it's unlikely that anything more than flurries will fall from these clouds. By Friday night, this clash between airmasses aloft becomes a bit stronger, and the approaching disturbance moves overhead. This combination is likely to lead to widespread light snow Friday night through most of New England, tapering off by Saturday morning.
While Saturday dawns cloudy and relatively quiet here in New England, the atmosphere several thousand feet above the earth's surface will be very busy through the end of the week and into the weekend, and this will manifest itself in storm development for the upcoming weekend. After a series of strong energetic disturbances drop south along the east side of the ridge of high pressure over the Western United States, they will merge and aid in developing a new storm at ground level, along the Northern Gulf of Mexico coastline. The proximity of this storm to such a significant source of warmth and moisture will feed storm intensification, and as the area of low pressure draws northeast over the Eastern Seaboard later Saturday, light snow will develop across New Enlgand. As the storm center moves northeast and along the Eastern Seaboard, snow will intensify Saturday night. The real questions on how this will evolve take over at this stage in the game. Aloft, at the jet stream level, the pattern is very progressive, and will be eager to pull this storm quickly off to the east, giving Southern New England a glancing blow of accumulating and perhaps plowable snow but not a blockbuster storm. The fly in the ointment revolves around the shear amount of moisture feeding in from the Gulf, the warm ocean temperatures off the east coast, and the cold air that will be in place through New England. The combination of all these factors will allow this storm to develop handily, and if it should develop quickly enough, it would slow the ambient wind flow, allowing the storm to pull north along the Eastern Seaboard. At this point, it's truly too early to speak with certainty on which of these scenarios will play out, but I can say that I would like to see indications that the jet stream winds will slow down a bit more than I'm currently seeing before I can feel comfortable forecasting a blockbuster storm for New England, and that while I feel snow - accumulating and plowable snow - is likely through a majority of Southern New England, I'm waiting a bit longer before "pulling out all of the stops" on this storm. Should it reach it's maximum potential, however, it would be a very impressive creature with blizzard conditions Saturday night into Sunday, so the stakes are certainly high with this storm development.
Sunday's forecast hinges largely upon how quickly and exactly where this storm develops and moves, but most likley snow lingers in the morning regardless of which storm scenario plays out, and as the storm draws east of New England and intensifies, winds will be gusty and cold air will spill into New England. The next upper level disturbance swings through on Monday, bringing a chance of snow showers later in the afternoon.
Obviously there's plenty to keep an eye on over the next several days, but for those of you who enjoy looking farther into the future, there are some signs coming back on how the rest of February may play out. Though I think we've shifted into what will - on average - be a wintry pattern through the end of the month, some atmospheric reshuffling appears to be in the cards around and just after Valentine's Day. As mentioned above, while we're currently in the heart of cold Canadian air, and this cold air extends west into the Northern Plains, heat is building under a strengthening high pressure center in the Western United States. Strong signs are for this high pressure center to grow very large and very warm over the next several days, and though we deal with a storm threat Saturday night into Sunday, this will mean that our replenishing supply of cold air will be temporarily cut off, since we've been feeding our cold in from Alaska. While this is likely to result in 3-4 days of somewhat warmer weather - at or somewhat above normal temperatures for this time of the year - next week, I don't think it's the end of winter, or of the new wintry pattern by any stretch. I continue to foresee a pattern shift allowing cold air to return once this Western high pressure ridge has reached its peak next week, and with an active subtropical jet stream nearby, multiple opportunities for cold and moist systems will exist in the new pattern. It's obviously not a comfortable feeling to make a prediction of a return to cold and multiple chances for snow, then see even a brief return of warmth, but indications of this being only a brief stint with milder air are fairly strong, so I remain confident that winter turns back on at the end of the month.
Enjoy your Thursday.
Matt
Matt's Technical Meteorological Discussion: Updated Thursday, February 9 at 4:10 PM
And away we go! Time to dig in for what lay ahead this weekend, but let's do it one step at a time.
12Z 500 mb analysis shows a building ridge just off the West Coast as shortwave energy over Northwest Canada slides southeast across the Northern Plains and into the still-digging Eastern US trof. We're going to be working with a number of factors this upcoming weekend - all factors that we've been monitoring together through these discussions for several weeks now, ranging from an anomalously high amount of available energy after record warmth across the United States (I forgot to mention that record earlier this week - will try to remember to include these stats in the Weather Summary tomorrow) to a tremendous clash of airmasses between Gulf of Mexico moisture and warmth with still southward building arctic air that's being reinforced by yet another arctic front overnight tonight, to a positively tilted trough that just barely diffuse enough to our west to actually help in storm development, as we looked at together a few days ago - rare to thank a positively tilted trough for future storm development, but this is a rare pattern, so we'll take what we can get.
Arctic front moving southeast this afternoon across New York State and toward New England, and will bring enough convergence and low level lift - coupled with orographic assistance - for snow squalls through most of Vermont, the Berkshires, snow showers in the Litchfield Hills of CT, and snow showers/squalls for most of Northern NewEng north of the Lakes Region of NH to Augusta, ME. General accumulations in these areas should range between 1 and 2 inches, but a full-fledged overnight snowstorm is in store for localized portions of the higher terrain of the Northern Green Mountains, where close to 6" will fall overnight Thu ngt into Fri AM, and enhancement along the Eastern Maine coastline also looks like a good bet where dynamics and moist low level flow bisect.
The remainder of NewEng will see downsloping winds squashing most of the activity but enough cold advection a few thousand feet up for plenty of clouds to fill in during the night and perhaps a few flurries. As cold advection wanes predawn Friday, skies will be allowed to partially clear briefly Fri AM before next shortwave already brings cyclonic vorticity advection into NewEng during the day on Friday with warm advection commencing relatively early not only aloft but even down to 850 mb by 18Z. The natural reaction here is going to be for cloud formation at most levels through the day. By late Friday, dominant NW flow takes hold and dry advection actually resumes as baroclinic zone nudged ever so slowly farther south, laid across Central and Southern NewEng and across MA, where light snow will develop Fri Ngt with the passage of vorticity maximums from both the west and the north thanks to confluent flow over NewEng. This location of the light snow band is farther south than indicated by the NAM, but in good agreement with the WRF and the GFS - which isn't putting out much precip but has it in this location. Total QPF will be light, but some enhancement will be possible all along the East Coast of MA with easterly flow providing ocean enhancement for 1-2" amounts possible in extreme eastern communities from Cape Ann to Cape Cod and Nantucket.
Then the real show begins. Let's take this at what we know: A series of shortwaves dropping into a positively tilted trough will merge, combining into a stronger upper level low that will dig and turn the trof neutral as the shortwave energy rotates around the base of a closing upper low. Ample Gulf of Mexico moisture that has been locked south is tapped, and the the center of low pressure center jumps to the Carolina coast as upper level energy outruns the initial surface low. From this point on, it's true that we have an upper level pattern that would appear at first glance to favor a rapidly moving storm that even would have the potential to shoot south of us. When I first looked at everything early this morning, I saw the same things we're still seeing now, which is an upper level pattern that begs for a progressive storm, but low level dynamics that are a perfect setup for a very heavy dumping of snow over most of New England. The trend now is to enhance the shortwave ridging ahead of the storm, which is providing enough of a westward track to bring the storm over Southeast NewEng. I would argue that this storm will almost entirely follow the strong baroclinicity once it gets cranking along the east coast, and this means taking into account the same zone we mentioned above that sinks south of NewEng at 850 mb on Saturday. Additionally, looking at the surface synoptics really helps to drive home the point that this could be an extremely productive snowmaker - a 1024 surface high pressure cell centered over the Mountains of Maine early Saturday under confluent flow low level and aloft helping to lock in the cold, -24 C at 850 C just northwest of the St. Lawrence River that's feeding directly from the Aleutian cold pool we've been eyeing for the past few weeks, waiting for it to lead us to our cold and snowy February pattern. At long last it appears everything we've been patiently watching is fitting into place - the cold air drain at low levels, the positively tilted trough allowing for a conglomeration of energy, the abundant moisture and warmth - and therefore abundant energy - in the atmosphere, the warm ocean temperatures and the baroclinicity that sets up from all of these features. Add to that strong diffluence aloft and we're developing what should be a very efficient precip producer on Saturday.
One excellent point that needs to be made is that this is a very progressive system, even with the shortwave ridging that may develop ahead of it. The problem is that it's also a quickly intensifying system and this means inflow will be ample. Winds will also be cranking and blizzard conditions will be possible briefly, especially along the coastal plain of Eastern NewEng and in the Southern Mountains, but let's remember that its likely to happen overnight Sat ngt which means weather nuts like us realize it but the public sleeps through it. Power outages would be a concern, however, especially along the coastal plain. Coastal flooding will need to be considered, but astronomically lower tide on Saturday night helps out. Additionally, with Southern NewEng on the northwest side of the vort max track this keeps us in midlevel warm advection through Saturday night until the vort has passed, with 700 and 500 mb flow indicating wrap-around precip banding as well, later Saturday night and into Sunday.
With the cold air in place, we have to acknowledge a fluff factor here as well, and this snow will be quick to accumulate. The bottom line here is that this storm will be a perfect one for those who have been longing for snow - widespread snow all the way to the Canadian border, and timed almost perfectly with regard to limiting disruption to plans as the worst comes between Saturday sunset and Sunday sunrise to mid-morning. QPF amounts of 1" should be widespread across Southern NewEng with a stripe of 1.25"+ across much of MA and Nrn CT to the northwest of the low track, which I expect to be over Nantucket and Chatham. The arctic air sets up a low level coastal front that will establish through interior Eastern MA and enhance snow amounts from interior Southern NH to the Merrimack Valley to the Worcester Hills/Metro West area into Nrn RI. Additionally, the track I'm forecasting will mean a rain/snow mix on Cape Cod significantly cutting back on accumulations there. I don't really need to mention it here in the technical discussion for those who are weather savvy, but this solution is based upon the undeniable trends in the guidance. Should a dramatic shift toward a more progressive solution occur - and we do know that significant changes can occur over 48 hours...ESPECIALLY with this storm where we've noted different models chiming in at different times thanks to a very delicate shortwave interaction - this overall thinking would have to be ammended significantly for a tamer solution.
After snow winds down Sunday morning, winds will howl from the northwest and a chunk of the cold air in Eastern Canada slides south to hold temps well below guidance, in the middle 20's most areas.
Part of what keeps this system moving is a strong kicker coming in from the west, and this shortwave will bring snow showers and heavier squalls later Monday as it moves through NewEng.
As for my thoughts on the longer range, those laid forth in the weather summary above hold, which is that this wintry pattern rolls on, though perhaps a brief interruption from the 15th to 17 or 18th when temps will be at or above normal, but only in preparation for the real fun to begin. Consistent signs of multiple major storm threats the week of the 19th need to be monitored and it's late enough that I'll skip that opportunity now, but the bottom line is that the cold is cutoff only briefly next week thanks to the ridge pulse over the Western US and Eastern Pacific, but that's the only way to pinch of the supply of cold, and it simply won't pulse strong enough, long enough, to hold back the flood of cold that will return for the remainder of the month and into march, and with both the Pacific and Gulf open the last half of February, this will help to feed the major storms I'm expecting. Does every one of them hit New England? That would be crazy to answer right now.
But we all have to start somewhere, and it appears New England starts Saturday night.
That's all for today.
Matt
