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 linked to the daily forecast at the top
of the page, a general non-technical weather summary below, and when
available (most days) a detailed technical meteorological discussion
will follow by mid-afternoon. My email is contact@mattnoyes.net. This blog is for you, so I hope you enjoy it! -Matt Noyes
Tuesday Podcast: Issued
Download Daily_Weather_Synopsis.mp3
Yesterday's General Weather Summary (today's will be updated by late morning):
New England snow lovers, rejoice! A major winter storm is on the
way after two relatively quiet days to begin the week. This storm
appears ready to thrive in a classic New England winter storm setup,
with a strong high pressure cell to our north in Southern Canada
supplying cold air, and a deepening (strengthening) storm moving along
the coastline.
In the meantime, Monday has dawned with intervals of clouds amidst
plenty of sunshine for most, and winds were already active at sunrise.
This is a sure sign that winds will remain active through the day with
westerly gusts to 30 mph at times, active ahead of an approaching
arctic cold front. This front marks the leading edge to a reinforcing
shot of Canadian cold that will actually result in falling temperatures
through the day Monday across far northern New England, including the
Champlain Valley. This reinforcing arctic air will be an important
ingredient in our upcoming storm, and also will serve to determine a
rain/snow line. In the meantime, however, it merely marks the
beginning of a cold air drain out of Canada, with active northwest
winds early Monday night producing wind chills below zero in most areas.
By Tuesday morning, the delicate interaction between the fair
weather cell (high pressure) over Southern Canada and the developing
storm (low pressure) to our south and west. The midweek storm taking
aim on New England will actually be the combination of energy and cold
air over the Northern Plains, energy and moisture over Oklahoma and
deeper moisture out of the Gulf of Mexico and over Florida, all evident
on Monday morning satellite imagery and upper air analysis. These
three areas of disturbed weather will all interact along the
Mid-Atlantic coastline later Tuesday. During the interim leading to
Tuesday evening, however, expect to find quiet daylight hours across
New England on Tuesday. There will, however, be a definite chill to
the air as evidence that arctic air will be re-established, and signals
that change is underway, beginning with effects both high in the sky
and here at ground level. On the ground, winds will slacken (weaken)
during the day Tuesday, but will shift direction from northwest to
northeast as air flows out of Canada and into the surface storm center
moving east across the Central Appalachians. Morning sunshine will
also fade behind increasing "cirrus" clouds Tuesday afternoon - high,
thin, wispy clouds made up of ice crystals that are found several
thousand feet in altitude and often serve as a harbinger of approaching
atmospheric moisture. This circumstance will be no exception to that
rule, and radar imagery Tuesday should indicate a band of mostly light
wintry precipitation lifting northeast out of our nation's Capitol.
Clouds will thicken and lower in the sky late Tuesday into Tuesday
evening as this band of precipitation approaches, blossoming along the
clash between cold air in the Northeast, and incoming warmth and
moisture aloft.
In fact, as Tuesday night progresses, a greater clash of airmasses
will result as the moitsure-laden air from farther south along the
Eastern Seaboard, and fed by the merging disturbances, moves northward
into our recently reinforced arctic air. This increasing clash of
airmasses will mean an increasing intensity to the precipitation band
lifting northeast across New England, likely arriving to southwestern
Connecticut around 7-9 PM and chugging northeast thereafter, spreading
over most of Central and Southern New England by dawn Wednesday, and
even penetrating into parts of Northern New England, as well. In fact
the farther south one is, the more snow that will be sitting on the
ground Wednesday morning, with a few inches in most of Central and
Southern New England, and a few interior Massachusetts and Northern
Connecticut communities already nearing half a foot! This will likely
only be the beginning of this storm, which is likely to bring blizzard
conditions through the interior of Central and Southern New England on
Wednesday.
A fair question to ask with regard to this storm is: How am I so
sure this system is going to be a doozie for New England? We've
watched storm potentials pass south of New England earlier in the
season, and even I'm often conservative from a couple of days before a
storm, aware of how much can change. In this case, things certainly
can change that would have big impacts on New England, but not so much
with regard to whether or not a storm blows through us. In this
instance, there is remarkable agreement that a strengthening storm will
pull from the Mid-Atlantic coastline, passing close enough to New
England to bring a winter storm for one and all. The points of
contention with this event include how far northwest warm air will
penetrate aloft (controlling the rain/snow/sleet/freezing rain
potential) and, accordingly, exactly what track this storm will take.
At this point, the combination of arctic air, milder ocean-modified air
and the retreating arctic front appear to favor a track directly over
Cape Cod - probably somewhere near Yarmouth - Wednesday evening just
after sundown.
So what else can we expect with this storm, besides a swath of snow
Tuesday night that will create treacherous Wednesday morning travel?
As the storm center develops off the Mid-Atlantic coast Tuesday night,
a renewed slug of deep tropical moisture will interact with cold air to
create a replenished swath of wintry precipitation from Washington D.C.
to the Mid-Atlantic. Additionally, the strengthening counter-clockwise
circulation of air around the storm center will bring new Atlantic
moisture into the storm and into New England. The combination of
merging energetic disturbances, ample deep moisture and ocean enhanced
low-level moisture and a sharp temperature difference between arctic
air inland and ocean-warmed air farther southeast, will mean an
impressive strengthening storm center. As the storm cranks up and its
central barometric pressure lowers, winds will crank up as well. In
fact, winds may gust to 50 mph along the coastal plain of Southern New
England, and frequent gusts to 35 mph are possible inland. Along the
coast, these winds will be most fierce later Wednesday, stirring seas
to over 20 feet and resulting in coastal flooding for flood-prone
northeast facing areas at the time of high tide Wednesday evening.
Oddly enough, while northeast winds will be prevailing near the coast,
interior locales may actually see a strengthening northwest wind
instead, as air flows into the center of the deepening storm. This
change in wind direction is very important for the overall scenario,
and is the reason I'm forecasting lots of snow and temperatures only in
the teens to around 20 for interior New England on Wednesday, as a
northwest wind will suppress the rain/snow line to southeastern New
England during the storm. So, while the combination of frequent gusts
to above 35 mph and a combination of heavy snow and blowing snow will
reduce visibility to below 1/4 mile for some of the interior on
Wednesday - blizzard conditions - the closer one gets to the coastal
plain and especially to Southeastern Massachusetts, Rhode Island and
Southern Connecticut, the better chance some mix will be involved. On
Cape Cod, for example, we're likely to go entirely to rain after a
period of an inch or two of snow Tuesday night. In Southeastern
Massachusetts, we're likely to see a few inches of Tuesday night snow,
but will may see a mix with and change to sleet and freezing rain for a
time later Wednesday, which could be a major problem with regard to
power outages when combined with the wind. Along and near the coastal
plain, we're more likely to see a definitive rain or snow delineation
thanks to a sharper division between northeast wind and east or
southeast wind that should make quite a difference. Farther inland,
areas from Central Massachusetts to interior New Hampshire and much of
Maine will stay all snow or mostly snow, meaning accumulations of one
to two feet would be possible.
It's important to keep in mind the dual aspect of this storm - that
is, one band of snow Tuesday night, then a second round later
Wednesday. Though the first round will bring the most widespread snow
with little challenge of precipitation type, it's the second round
later in the day Wednesday that will be by far the most intense, as
tropical moisture, strong energy, and a sharp clash of arctic and
tropical air create a "bombing" storm offshore. It's most likely that
as the storm strengthens so quickly, it will literally snap cold air
southeast again, resulting in a change to snow for the last few hours
of precipitation in southeastern parts of New England Wednesday
evening. But interior Central New England won't be the only ones
seeing impressive snow - Maine could bear the brunt of this storm. The
southern half of New England sees the storm in two waves, as
mentioned. We also see the storm's effects as a tropical slug of
moisture and the driving northern energy are just beginning
interaction. By later Wednesday, as the intense shield of
precipitation with "round 2" shifts northward, the two aforementioned
players are merging into one amazing storm east of Maine. This should
create blizzard conditions for much of the coast of Maine, and very
heavy windswept snow for the interior. In interior New England - both
north and south - one to two feet of snow is possible if the storm
remains all snow in these locales.
By Wednesday night, snow will be shifting through Maine slowly,
ready to shut down for Thursday. Arctic air should continue to bring
blustery conditions on Thursday - with a mainly dry day in the drier
air behind the powerhouse storm - and then again Friday when a
follow-up disturbance moves east and brings another chance for a few
areas of light snow.
Overall, there are some subtle things to work out with this upcoming
storm that will have large impacts on who gets what and where. But at
this point, this appears to me a classic situation of a bombing New
England winter storm with blizzard conditions through the interior.
I'll update this discussion as my thoughts evolve in the coming two
days.
Matt
Matt's Technical Meteorological Discussion: Updated Monday, February 12 at 2:40 PM
All eyes on the midweek storm, but let's go thru the motions of what
comes first. Arctic front crossing NewEng this afternoon has brought
snow showers to Nrn half of NewEng with instability Sc deck developing
in low level cold advection above warmer ground. Temps have fallen in
Nrn NewEng and as front pushes S, areas in the M/U30s will drop quickly
this eve. Temps go below zero north, singles south, wind chill
widespread subzero. Cold air is dry air and sun is the result for most
areas early Tue. Ci deck in by midday and thickening/lowering thru the
day as winds begin to swing from NW to NE around belly of sfc ridge
extension and weak ageostrophic flow establishes.
Upcoming storm will move thru in two rounds, both to be determined
by synoptic scale warm advection. First swath of warm advection comes
thru Tue Ngt and this will be the first round of snow, and should be
snow for all spots. This swath alone will drop between 3 and 5 inches
for most of Central and Southern New England with a few locales -
especially with elevation - checking in with 6 inches when round one
winds up early to mid-morning Wednesday. There will be a break in the
action thereafter - though perhaps not nearly as pronounced in Northern
and North-Central NewEng where gradual isentropic upglide continues -
for many locales while the main low (and the big show) organizes.
There is an impressive confluence of airmasses that come together for
this event, from the vort max over the Nrn Plains producing snow, to
the moist shortwave with blossoming rain over OK/AR/MO that's already
expanding upon interaction with northern wave, to the deep tropical
moisture over Florida and the eastern Gulf of Mexico. It's this
tropical infusion that serves as a bit of a wild card for development,
and truly is assisting in bombing the storm center as it speeds
north-northeast on Wednesday. First of all, let's start with observed,
which is dewpoints of -15 to -25 F across Southern Ontario and Southern
Quebec heading for Nrn NewEng. This is the air that moves in tonight
and is with NewEng on Tue, locking in snow Tue Ngt for even the Cape
and Islands where a couple of inches will probably fall Tue Ngt thanks
to cold antecedent airmass and northeast wind component. Thereafter,
the difficulties are immense with judging the thermal profile of the
atmosphere, largely because our anticyclone is dying while our cyclone
is bombing. Also in the realm of current obs, interesting to note that
Tim Kelley watches lightning plots before storms and informs that the
severe wx is farther north than we like to see it this afternoon for a
mostly-snow event in Southern NewEng. This anecdotal reference argues
against a cold scenario, but is not a hard and fast determining factor.
By Wed AM, the low center has drawn to the Mid-Atl coast and already
is undergoing rapid strengthening. In NewEng, I have some problems
with the NMM solution - certainly of 00Z and to a lesser extent the 12Z
run, which has begun to come around. If one were to look at guidance
consensus, a track over Cape Cod near Yarmouth or Dennis would be the
most favored solution, and I'd argue the weather pattern supports this,
as well. It should be difficult for the primary low - which the NMM in
particular is keeping an important player - to survive to the extent
it's progged to as it encounters the arctic air. Instead, the focus
should shift quickly to the bombing coastal low, a la ECMWF and now the
Global Canadian. Meanwhile, what is well agreed upon is an extremely
tight thermal gradient at both 850, 925 and the sfc. With ageostrophic
flow taking over into this bombing storm, that will certainly fight
warming at the sfc as winds go NW in much of interior NewEng and this
locks in cold air at the sfc. Therefore, I think trying to change to
rain far inland is a NMM-based solution that looks unreasonable.
Aloft, it will admitedly be harder to hold the cold at the 850 mb
level, as warm advection wraps around the north side of this bombing
low, and is further propelled NW by winds ripping at over 70 kts in
llvl jet cores! When you factor in the significant chunk of tropical
entrainment from the Ern Gulf of Mexico, that further adds to the
warmth available, as well as, of course, the moisture. But what it
also does is fuel tremendous baroclinicity that will further promote
the bomb to deepen. Therefore, I do expect subsequent guidance runs to
feature a southeast shift of the thermal ribbon as the guidance should
weaken the influence of the primary low and consolidate more to the
coastal bomb, which would result in a SE crash of the baroclinic zone,
thereby shifting the rain/snow line considerably farther southeast.
This modified solution is close to the 850 mb temp forecast of the
ECMWF, and also is consistent with the behavior of a dense, low level
arctic airmass when experiencing ageostrophic flow. A coastal front
would be likely to develop, and the very same front moving thru NewEng
as of this writing on Monday would be retreating and likely serve as
another boundary that would become assoc with the coastal front.
Hence, my reasoning for a colder solution that keeps the potential of
blizzard conditions thru the interior.
Even if I am wrong and the bombing storm instead of sucking cold air
from the west and northwest instead pushes warmth in aloft, the
ageostrophic surface flow should still be sufficient to ensure any
precip would be either sleet or freezing rain, not plain rain,
excepting Cape Cod and far SE may, as well as areas south and east of
the coastal front on especially the South Shore of MA where
ocean-modified air would play a big role. Farther inland, and
especially around Concord and Manchester, NH thru most of VT, NH and
especially ME (even at the coastal plain of ME), cold holds strong and
storm is mostly snow, with 1-2 feet probable. Again, if my thoughts of
the baroclinic zone being farther SE than currently progged by
guidance, these amounts would verify for interior South-Central and
perhaps even far interior Srn NewEng as well.
Regardless of ptype, wind is a big concern. As seen in graphics
above in General Wx Summary, I'm expecting gusts to 50 mph at this
point, but with the strength of this low center, stronger gusts are
certainly a possibility. In fact, a warmer solution would favor more
mixing of wind to the sfc. Nonetheless, these winds will crank the
seas up over 20 feet and coastal flooding is a concern in the Wed eve
high tide cycle, which is astronomically lower than the AM tide cycle
when winds don't raise a red flag, but the wind and seas will be
intense so this remains a concern for the eve. Farther inland, two
problems with the wind: Cold locales see blizzard conditions Wed
afternoon and "warm" locales (aloft) see strong gusts with sleet and
freezing rain. Again, if a cold solution verifies, this sleet/freezing
rain potential will not be all that big, but I have been acknowledging
the potential for this in especially southeast interior MA where a
protracted period of icing combined with strong gusts could result in
numerous power outages. As for the blizzard condition potential, this
would come with the second round of warm and moist advection that
couples with strong PVA in slightly negatively tilting upper trof to
produce snows of a couple of inches per hour in a thick band lifting
from S to N Wednesday afternoon into Wednesday eve/night.
I'm holding cold arctic air in place for the end of the week thanks
to 970 or sub-970 mb low sitting NE of ME and high to our west, keeping
NW flow. Snow showers and heavier squalls in mountains/hills a good
bet Thu thanks to vort coming thru, tho good mixing and downslope flow
may lessen chance farther S. Some light snow back in the fcst for Fri
with another upper level feature poised to move thru.
We'll see how things play out - from a forecasting perspective we
still have time, and the next few cycles of guidance will obviously be
pivotal in determining whether my hunch of crashing the thermal ribbon
southeast is accurate. Even if it's not, I don't think the impact is
huge for many areas speaking spatially, though does affect a large
population for those of you within 20-30 miles of the MA Turnpike from
Springfield to Boston points SE!
Matt
Snow reports: MA/Nrn CT/SW NH | Western ME/NH | Vermont | Southern VT/Western MA/NW CT | Southern CT/NYC
