Welcome to the weather blog - a regular Monday through Friday discussion of the weather! While the discussions usually will only come on days I'm working, I'll issue special updates when the weather warrants. I will always post to let you know when no discussion is expected if I'm away on vacation, etc. - if no update is here and no info is available, that likely means the server has temporarily gone on the fritz and I will update as soon as technically possible. 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. My email is contact@mattnoyes.net. This blog is for you, so I hope you enjoy it! -Matt Noyes
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Matt's Quick Weather Synopsis: With a cold front draped over New England and sagging southward across Southern New England today, we'll find the focus for some puffy cumulus clouds to develop Thursday afternoon, and south of the Massachusetts Turnpike a few of these clouds may grow just barely tall enough for a few sprinkles or very light showers of rain. The bulk of the day, however, and the bulk of the region, will stay dry under a blend of sun and clouds and hihg temperatures slightly above normal for the day. This cool front marks the leading edge to a reinforcing shot of cool and dry air that will settle into New England Thursday night, bringing temperatures into the twenties and thirties. This cool start Friday will yield a cool finish, as well, even though sunshine will be plentiful, and with a large area of high pressure - fair weather - building over New England from Canada for the weekend, expect continued bright but brisk conditions. Clouds are likely to increase later Sunday as a developing ocean storm over the Canadian Maritimes backs westward toward New England, and this storm will most likely bring a period of cloudy, cool and showery weather for the first half of next week. -Matt
Morning surface analysis indicates a cold front is draped across Central New England Thursday morning, and this boundary is the leading edge to a reinforcing push of cold and dry air settling southward into New England from Canada. While this cold front sparked plenty of rain and snow showers across Northern New England on Wednesday evening, the dry nature of the air is likely to only allow for puffy cumulus clouds to build high enough for a few sprinkles or light rain showers south of the Massachusetts Turnpike later Thursday afternoon.
The stubborn cold front will finally clear New England by Thursday evening as a new area of cool Canadian high pressure settles south and east toward New England. This air is cold enough in nature to bring us the coldest night of these chilly overnight periods thus far, with widespread lows in the twenties across Northern, Central and Western New England, as well as deeper valleys in Southern New England. Most cities in New England recorded fairly cold temperatures in the middle 1940 (1945 and 1947) on April 28, so it's unlikely that lots of spots will record record low temperatures Friday morning, though a few spots may set record cold. Regardless, it's another night of bringing in delicate flowers or plants you may have decorating the front steps!
With a clockwise flow of air around centers of high pressure, this will yield a northerly wind on Friday, and at the eastern coastlines, a bit of an ocean component is likely, as well. The northerly wind flow, combined with a shallow layer of high enough moisture for some puffy cumulus cloud development through the day Friday, will ensure that New England remains cool, though the surface high pressure cell of fair weather will keep most areas dry.
Though an area of high pressure - a fair weather cell - will build in at the surface, the atmospheric situation aloft is somewhat more complex. Over the last couple of days in this discussion, together you and I have been discussing a trough (a dip) in the jet stream winds over New England. Remember that the jet stream winds race high in the sky and are responsible for steering storm systems and acting as a thermostat, separating cold air to the north from warmer air to the south. With these jet stream winds taking a dip over the Northeast, this puts New England on the cool side of the thermostat for the next several days, and it also steers a series of upper level disturbances over New England, as they merge in the base of this jet stream trough over the next several days, eventually developing a stronger storm east of New England by late this weekend. In the meantime, however, each upper level energy center racing through aloft provides the impetus for showers, if only the effects of this energy could overpower the dry air that will be in place. While this looks unlikely, it's at least worth noting that if any of these disturbances are stronger than currently forecasted, a sprinkle could develop either Friday or Saturday afternoon. Barring stronger upper level disturbances, however, I continue to expect dry, mostly sunny and brisk conditions to persist into the weekend.
By Sunday, the conglomeration of multiple upper level disturbances dropping into the Northeastern United States trough will encourage the development of a storm center east of New England, over the Canadian Maritimes. While the bulk of this potent storm will stay east of New England, we always need to be cognizant of the potential for bands of moisture to be thrown back westward from storm circulations like this, resulting in bands of clouds and sometimes showers, as well. At this point, my take on this is that we're likely to see some increase in cloud cover during the day Sunday - especially later in the day - but we're also likely to stay dry.
By Monday, Tuesday and Wednesday, we'll actually have our eye on two storm systems - one will be the slow moving storm to our east, and the other will be an equally slow-moving but moisture loaded system moving east across the Tennessee Valley. There are a couple of possibilities as to how this plays out, but no matter how you cut it, chances are good for showers each of the first three days next week. One possibility is for the storm to our east to gradually east away from New England, allowing the next slow moving heavy-rain maker to trudge east toward New England, but this scenario is seeming a bit less likely. The most likely scenario, at least from guidance I have thus far, is for the storm east of New England to gradually move westward toward New England, throwing bands of rain showers into New England around the Western periphery of the storm on Monday. By Tuesday and Wednesday, it appears as though pieces of energy will break off of the new potent storm to our west, feeding into the ocean storm and allowing bands of showers to continue backing in off of the ocean through midweek. This would bring a prolonged period of cool, cloudy and at times showery conditions for a few days.
While there are still details to work out with the evolution of the storm for the beginning of next week, we'll focus on our stretch of bright but brisk weather, timed well for the weekend.
Have a wonderful Thursday.
Matt
Matt's Technical Meteorological Discussion: Updated Thursday, April 27 at 1:05 PM
Cold front evident this morning in wind shift, pressure analysis and weak surface Theta-E gradient with wave of low pressure rippling along front thru Hudson Valley as of this writing and set to move over Southern NewEng Thu afternoon. The passage of the cold front and low pressure wave, coupled with about 100-200 J/kg of CAPE and little if any convective inhibition will aid in healthy Cu development along and south of the MA Turnpike where a sprinkle or light rain shower is possible around time of max heating Thu afternoon. Elsewhere, dry airmass in place and negative theta-e advection continues from the north with wind shift behind the front. With this airmass in place overnight and winds diminishing, conditions favorable for cooling and widespread 20s are likely in a large portion of NewEng, lower 30s many remaining Southern locations which is near dewpoint so areas of fog and frost are likely.
Lingering pockets of moisture in the lower levels on Fri evident as of this writing as Sc deck west of St. Lawrence River Valley in Southern Canada will allow clusters of clouds to pass through NewEng Fri from AM to PM. These clouds may have some small effect on insolation but even so we should mix to about 850 mb, which doesn't help us to warm any as the air at that level is below 0 C and even with compressional heating of the parcel it will still have an overall cooling effect on the airmass, keeping most lower elevation temps in the lower to middle 50s, cooler on hilltops where there's less atmosphere to mix.
Saturday looks delightful with deep dry air and NewEng sandwiched between a strengthening and soon-to-be retrograding Maritime storm, and a moisture-loaded soaker with widespread severe weather outbreak from the Southern Plains to the Gulf Coast to the Upper Midwest from Fri Ngt thru Sun AM!
In the extended period it's becoming more and more clear that the GGEM was onto something important over the last few days by deepening and retrograding the Maritime storm. It was of concern and respect for this springtime phenomenon of a strom developing in a climatologically favorable cyclogenesis region during April and May that I've maintained increasing clouds for later Sunday. With additional guidance coming around to this solution of an amplified omega blocking pattern and a retrograding maritime storm, rain goes into the forecast for the start of the week, and it appears as though as the ridging to our west pinches off, energy from the potent Central US storm feeds into the ocean storm piece by piece, aiding in retrogression and aiding in keeping warm advection wrapping around the storm and throwing precip into NewEng, along with what will likely be a cool northeast or east flow that will keep NewEng cool and cloudy thru Wed.
There are understandable concerns in the marine community regarding this storm, given memories of the May nor'easter from last year, and I would expect those of you in the marine community to remain interested in how things develop as the memory of one year ago is renewed. At this point, I don't see something as severe as that anomaly, though the winds likely will crank especially on Monday night through Tuesday. The reason I say that is because we'll see the surface reflection of a retrograding upper low on Monday which will tighten the pressure gradient from the northeast and kick the winds up later Monday, but by Tuesday the remaining energy associated with the Central US storm will kick east as an upper low and pass south of NewEng on Tuesday, and though this storm will have already matured at the surface over the weekend, it will likely form a reinvigorated surface low as it approaches the mean trough position off the NewEng coastline. I think the bigger concern is for large swell on NewEng waters for the first half of last week that may limit offshore money-making potential given that we'll be dealing with a strengthening onshore flow with a fetch that will extend all the way from the Grand Banks to NewEng and set up later Sunday all the way thru midweek in a time of high tide cycles. So, while this storm doesn't appear to be as violent as the one of one year ago, keep in mind that it still may have some marine impacts to be contended with.
FYI...I'll probably try to address this in the General Wx Summary tomorrow and repost the techie discussion unless there are some noteworthy thoughts or unless I'm well ahead of schedule.
Have a great afternoon.
Matt
