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:
Marathon Checkpoint Forecast (City, Temp, Dewpoint, Relative Humidity, and Wind):
Hopkinton: 52, 33, 48%, NNW at 10 mph
Ashland: 53, 33, 46%, N at 8 mph
Framingham: 54, 34, 46%, N at 11 mph
Natick: 54, 35, 48%, N at 11 mph
Wellesley: 54, 35, 48%, N at 8 mph
Newton: 55, 35, 46%, N at 10 mph
Brighton: 53, 36, 52%, NNE at 12 mph
Boston: 51, 37, 58%, NNE at 14 mph
With an area of high pressure building across Southern Canada and a storm center spinning over Nova Scotia, a cool north and northeast flow will take hold of New England. Signs of increasing moisture with this northeast flow will be evidenced by building cloud cover blotting out the sun for Central and Southern New England through Patriots Day, with overcast skies through most of Maine, Northern NH and Northern VT. By Monday night, northeast winds drive cooler and more moist air southward through most of New England, bringing a lowering cloud deck and even some drizzle and fog to Eastern areas. Tuesday dawns with plenty of clouds and lingering drizzle and fog, though the cloud base should rise during the day and Western New England is likely to break into some sunshine. With the storm stalled east of us over Nova Scotia, Eastern New England will remain relatively cool with plenty of clouds on Wednesday - though some sunshine is likely - while Central and Western New England will see plenty of sunshine and responding temperatures into the 60s. By Thursday, expect a great spring day for one and all before another shot of northeast winds - and corresponding cool conditions with building clouds - moves in for Friday.
General Weather Summary:
As a deep area of low pressure spins over Nova Scotia, stalling there for the start of our workweek, the counter-clockwise flow around the storm will help to direct winds from the northeast across New England. At the same time, a high pressure center to our Northwest, near James Bay, Canada, and with a clockwise flow of air around it, will be strengthening and further contributing to the propensity for a cool and increasingly moist flow into New England from the northeast.
The initial indications of the increasing moisture in the atmosphere for Southern New England has been waves of increasing cloud cover, pinwheeling around the western side of the stalled storm center over the Canadian Maritimes, dropping showers across Northern, Central and Eastern Maine, but encountering a bit of a drying northerly flow as the moisture travels south, bringing periods of clouds thickest after noontime, with cloud bases around 2500-3000 feet. The limited sunshine and northerly wind flow will, of course, limit just how warm New England can be on Monday, with most areas remaining below normal temperatures for today's date.
Overnight Monday night, the northerly flow begins to turn more from the northeast, and this introduces increasing moisture not only aloft, but also at ground level. The result will be a lowering and thickening cloud deck likely to be accompanied by drizzle and fog overnight, especially near the coastline. A few rain showers are possible toward dawn in Southern New England, as well.
While the near-surface atmosphere will dry enough on Tuesday for the showers to end, cloud bases to rise and for the fog to burn off, skies will likely remain overcast with moisture continuing to stream in aloft behind the stalled Scotian storm. Trying to nose eastward out of the Ohio Valley, however, will be drier and warmer air, and it's likely that the Western periphery of New England will break into some sunshine Tuesday afternoon.
Though the amount of moisture in the atmosphere will gradually decrease on Wednesday, it's likely that eastern communities will still see clouds bubbling up, especially during the first half of the day, while Western and Central New England break into the 60s under increasing sunshine. A similar scenario is expected Thursday morning, though by afternoon all of New England should be drying out nicely with a spring blend of sun and clouds.
At this point, it appears another "backdoor cold front" is en route for Friday - shifting winds around to the northeast and east once again, pushing deep warmth westward out of New England and bringing a cooler marine flow inland for most of our six-state region.
Cool air is likely to stick around with an onshore flow into next weekend, with showers especially likely Saturday night into Sunday.
Enjoy your Patriots Day!
Matt
Matt's Technical Meteorological Discussion: Updated Monday, April 17 at 1:05 PM
Increasing moisture progged in guidance playing out well and evidenced by widespread Sc popping thru Central/Southern NewEng while rain continues to fall periodically in Central/Northern/Eastern ME. Multiple vorticity maximums will drop southward over NewEng over the next 84 hours as upper low currently E of Nova Scotia retrogrades then stalls E of NewEng. The result will be a continued cool northerly flow deep into the atmosphere and temps at least in Eastern NewEng likely to verify below MOS guidance thru the period.
In the immediate term, rain in ME unlikely to penetrate very far south during the day with lingering westerly component, then eventually due N/NNE flow in lower levels of the atmosphere not conducive to moistening the column daylight Mon. The result will be continuing bubbling Cu field with input of moisture a few thousand feet off ground level and this Cu field will help to halt temp rises.
Overnight Mon Ngt, northeast flow will succeed in bringing moisture in as loss of diurnal heating allows air to cool sufficiently. Clouds should lower quickly from ME coast southward after sundown. Some question lingers in my mind as to whether we see fog/drizzle setting up in Eastern NewEng given Tds in the middle 30s, but daytime temps with incoming airmass over Ern ME are running in the 40s and as this air cools and Tds rise to near 40, certainly some potential to realize this in cooler locales, tho most may only see low deck. Backing this up is the fact that most locales don't go to a true northeast flow...more due north or just east of north in coastal locales...and this also would favor keeping the boundary layer slightly drier. Given this marginal setup which continues on Tue, even weak diurnal effects thru clouds will allow for fog/low clouds to rise in base altitude Tue, tho abundant moisture in the low levels will keep plenty of Sc in place, and tho a few breaks are possible as weak inversion breaks around midday, temps will be held in check thru most of Central/Eastern NewEng's clouds. Strong thermal ribbon evident in low level progs from E to W Tue and Wed, and this makes sense given cool and moist airmass wrapping around back of Scotian storm, while bubbling ridge to our west drives deep spring warmth toward NY State. Likely result is for sunshine to burn thru and temps to respond in Western NewEng both afternoons. Enuf dry air by Wed that even Eastern areas likely to break into decent blend of sun and clouds as diurnal effects and backing wind to NW downslope work their late-April magic.
More clouds may bubble overnight Wed Ngt along coastlines with loss of htg and vort lobes throwing cool air toward the coast, but once again this process should reverse Thu as sunshine does its work. Still, temps will exhibit coastal/inland discrepancy as wind flow eases Thu afternoon with low east of NewEng pulling away and sea breeze circulation likely to set up.
Meanwhile, the jet stream winds will continue to lift well north - and quickly - over the next few days. This is a typical spring transition and can mean big warmth, but with one upper level low stuck east of us, and another left behind by the jet stream over the nation's midsection, we not only have one low retarding warm advection, but another one yet to swing thru, and moving slowly thanks to the absence of strong jet stream winds. The result will be a weather sandwich for NewEng on Fri but don't bank on a warmup with a 1024 high expanding rapidly SE from Hudson Bay. This should pull a backdoor cold front into NewEng later Thu Ngt and set up northeast and east wind that will penetrate deep into the interior on Fri, holding most locales in the 50s for max temps. This shallow cold dome is always tough for the guidance to pick up on, which is why some MOS members are shooting for middle 70's on Fri. In reality, if there's any day this week for 70s it's going to be Thu away from the coastline where sea breeze will have no influence and 850s of +6 to +8 C will mix well under sunshine. But by Fri I expect the cool reaches of the approaching and expanding anticyclone to be taking hold of NewEng. At this point, Sat doesn't look substantially warmer - though likely a bit warmer as rain is likely to move E with next upper low and associated warm/moist advection slowly enuf to bring mostly dry day and while wind is still penetrating and onshore, it's SE rather than NE/E. The reason I favor a slower solution to precip advancement at this point is combo of elongated E-W trof axis with 1025-1030 mb high over SE Canada and extending SE over NewEng which should provide enuf subsidence and dry air to offset isentropic lift trying to ride northward ahead of slowly approaching upper low.
It may take until later Sat/Sat Ngt for strong enuf warm/moist advection for precip to develop, tho likely still a band of at least showers associated with baroclinic zone setting up over NewEng on Sun. As upper low center moves just S of NewEng ejecting east late Sun and on Mon, potential exists to wring out a moderate or even heavy QPF event. I say this because there is still plenty of vorticity assoc with this upper low, and sandwiched between two anticyclones with the eastern one providing moist Atlantic inflow, one would think the potential to crank out rainfall is fairly high. Coming in from the northwest is the next anticyclone, packed with some pretty cool air. While an imaginative mind could try to get this cold wrapped into the system for some backside snow showers, it looks a bit too slow to do that right now, but there's something to be said for the meteorological imagination and it's worth keeping in the back of our minds. Regardless, this should help to ensure that we keep cool air coming thru midweek next week, obliterating my plans from several weeks ago on a warm finish to April and delaying it to the beginning of May.
Have a wonderful Patriots Day.
Matt