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
General Weather Summary:
All Watches/Warnings/Advisories:
You can access active warnings for your area two ways through this site. 1) Use the "WeatherBug" utility on the top left of the page by entering your zip code. This utility WILL NOT download any software to your computer and is entirely web-based. If you do not know your zip code, I've included a link to a zip code lookup utility below the feature. 2) Use the link I've provided on the left of this page under the "Active Advisories and Current Conditions" section. Both of these tools are ALWAYS here on my page, despite the weather.
Useful links:
Latest river
observations and forecasts can be found from the Northeast River
Forecast Center by clicking here. Do notice the tab at the top of their map, to be sure you're looking at either forecasted or observed conditions.
Mariners, please utilize the links always located here on my page to the left, under the "Marine Interests" section.
Sunday Update:
Not many changes to the forecast for this well-advertised storm that will deliver on its promised intensity. Below, you'll find both Friday and Saturday's posts - Friday's has been left for those of you who haven't read these discussions in the past few days and want to get completely spun up, and Saturday's has been left because there's been little change to the forecast. So, let me just highlight some of the biggest concerns now, as we enter the storm, and I won't get into great detail since you can reference that in the previous discussions immediately below today's update here. 
Storm Track: Looks like the storm comes into extreme Southern New England - Southern CT - before stalling/looping, then shifting southeast. The slow nature and strong intensity of this storm keeps its effects around for most of this week, though the fiercest effects come early on.
Rain: Rain is developing in many areas Sunday morning, and will become torrential later in the day. Some areas are seeing snow (see below) but many Central and Southern New England areas will transition to all rain through the day Sunday. Torrential rain will spread across Connecticut Sunday morning through Sunday evening. The remainder of Southern New England will find the heaviest rain from Sunday evening through Sunday night. Central New England will find any snow changing to heavy rain that will last through most of Monday. Northern New England will find snow (see below) changing to rain Sunday night into Monday morning, though remaining as snow far North. Total rainfall amounts were posted in a map in Friday's discussion, but have been reposted below, and will total as much as 4"-5" average amounts in Eastern parts of Southern and Central New England, with at least 2" for all areas! This magnitude of rain will certainly be enough for flooding of streets and low-lying areas, and will also be sufficient for areas of "flash flooding" - rapid rises in streams and small rivers to above bankfull, that may result in some road washouts. Especially given the expectation of this to occur overnight Sunday night, please exercise extreme caution in night-driving and remember the rule "turn around, don't drown" by not attempting to drive through flooded roadways. Cars often stall in such situations. Some flooding of small rivers - and if over 5 inches of rain falls, even mainstem rivers - in the Merrimack Valley is possible Monday as rainfall runoff causes rapid river rises. 
Snow: Brief bursts of snow began the day in higher terrain of Southern New England. These should change to rain after accumulation of less than an inch in many areas. In the Berkshires and Central New England locales that see snow, a couple of sloppy inches are possible before changeover to rain. Farther north, heavy snow is still expected in much of Northern New England, though this will be mixed with plenty of rain in deeper valleys including the Champlain Valley. With elevations above 1000 feet, however, snow will accumulate 6"-12" Sunday through Sunday night. This heavy, wet, spring slop will mean numerous power outages, especially when its weighty effects are combined with an increasing Sunday night wind. Snow will fall throughout the day Monday in the Mountains of Maine and parts of Central Maine, from Fryeburg to Dover-Foxcroft and Millinocket northward. This snow will accumulate to as much as 18"-24" in these areas by the end of Monday - a major spring snowstorm that is sure to knock out power to these locations for several days, and residents in these areas should be ready to go an extended time without power utility.
Wind: No change to thoughts on wind from yesterday. Please refer to Saturday update below for details on expected hurricane force wind gusts to Eastern New England Sunday night through Monday, depending on location.
Coastal Flooding/Beach Erosion: Please reference Saturday update below for details on this, but I can add that this should be an epic coastal flooding event from the Northwest shores of Long Island to the Southwest shores of Connecticut. In these areas, major flooding will occur, and the National Weather Service is comparing this flooding for these areas to that of the Perfect Storm of 1991 and the March superstorm of 1993. Preparations should be rushed to completion for the 10-11 PM high tide. Follow any and all evacuation orders. Also vulnerable is the Eastern Massachusetts coastline in areas that suffer from an east or east-southeast wind. A minor to moderate coastal flood event is expected for many areas, with a 10-11 PM high tide. Equally concerning are the effects of pounding surf on beach erosion, which will put in jeopardy vulnerable structures along the coastline, especially from Cape Ann northward through the Seabrook, NH, area. Chances are good that if your structure is vulnerable due to previous beach erosion, you're painfully aware. Coastal flooding will occur again from either side of Merrimack River all the way through Midcoast of Maine at Monday morning high tide, then again Monday evening. A more northeast wind will take hold on Tuesday, and coastal flooding will be likely at most northeast facing shorelines that typically see flooding on a northeast wind.
Saturday Update:
We enjoy a calm and pleasant day before the big storm on Saturday,
with the forecast looking on track for a day in the 50s south, near 50
central and 40s north under plenty of sun and a few clouds. Clouds
should increase overnight Saturday night well in advance of the
approaching storm that will be strengthening off the Mid-Atlantic
coastline while pulling north toward New England on Sunday. Today's
discussion is meant only to build upon and supplement yesterday's
mammoth discussion below, so if you're looking for a full setup, you'll
want to read that one (included below) to get spun up.
The big question on this storm remains how far north it progresses
before slowing/stalling/looping then migrating south and southeast and
eventually departing. That uncertainty continues to hold the cards for
Monday's forecast, though the trend is toward a solution that would
pull the storm far enough north to at least bring it over extreme
Southern New England. But before we delve into that, let's touch up
what I know and what I believe to be the biggest and most immediate
concerns, and that is the scenario for later Sunday through Sunday
Night.
Rain: Heavy rain is still expected to spread across New England
from southwest to northeast Sunday, beginning in Connecticut early to
mid morning, then Central New England around midday and Northern New
England during the afternoon. Rain will become torrential later Sunday
through Sunday night, with total rainfall amounts indicated in the map
from yesterday's discussion (below) but expected to AVERAGE near 4" in
Eastern New England! That means some spots may be lower, but others
will be locally higher, and this is enough rain to prompt flooding of
not only streets, streams and low lying areas, but also of rivers.
Though you can always check for Watches/Warnings/Advisories from the
National Weather Service through the links at left, latest river
observations and forecasts can be found from the Northeast River
Forecast Center by clicking here. Do notice the tab at the top of their map, to be sure you're looking at either forecasted or observed conditions.
Snow: With a deep southeast wind flow, it's unlikely that we'll
find much snow in a lot of Central and Eastern New England, thanks to
modified ocean air streaming in off of the Atlantic. The farther west
and north one is, however, the more likely snow becomes thanks to dry
and cool air already in place, and a bubble of high pressure across
Eastern Canada that will be able to supply more cool air as the storm
center deepens to our south and draws air into its center, meaning that
cool reinforcing air will be tugged southward across New England. The
result will be developing snow and rain mix on Sunday afternoon
changing to mostly snow from Upstate New York through the Berkshires
and into Vermont, Central and Northern New Hampshire and Central and
Northern Maine. In the Berkshires, Southern Vermont and Central New
Hampshire, the snow should change to rain overnight Sunday night after
four to eight inches of snow. Farther north, however, through Northern
Vermont, Northern New Hampshire and Central/Northern Maine, half a foot
to a foot of heavy, wet, spring snow is likely, and coupled with
increasing winds, this will once again mean power outages. For some
areas of the North Country, due to persistent winds for a few days that
will make the job of repairing and restoring power service difficult,
outages may last a few days. Please note that my accumulations given
here are through midday Monday. Additional snow is possible Tuesday
(when snow may fall into even parts of Southern New Engalnd) and
perhaps Wednesday.
Wind: The wind is, of course, the biggest threat to mariners, but
will be a problem for us all. A corridor of fierce winds will develop
on the north side of the storm circulation, and that corridor of wind,
blowing from the east and east-southeast, will lift from south to north
late Sunday into Monday. The first areas to see the increase in wind
will be the South Coast of New England, where afternoon winds of 30-40
mph with gusts to 50 mph will arrive by later Sunday afternoon. This
will only be the beginning of the wind, as the wind corridor is
expected to increase in intensity as it pushes northward, resulting in
gusts to over 60 mph along the South Coast of Connecticut, and Sunday
night gusts to hurricane force (74 mph or greater) on Cape Cod and the
Islands in especially the first half of Sunday night. These hurricane
force gusts will move up the coast of Eastern Southern New England
overnight Sunday night, with gusts to 60 or 65 mph possible through
most of Eastern Massachusetts, and this will down some trees and power
lines. By Monday morning, the corridor of fiercest wind will shift to
Southeastern New Hampshire and Southern/Coastal Maine, where gusts to
hurricane force would still be a possibility early Monday. Thereafter,
much will depend upon where the center of this storm stalls or loops.
At this point, if the storm were to stall over far Southern New
England, winds would gradually come around to blow from the northeast
on Monday and then last into Tuesday, with the most intense wind from
Cape Ann northward along the Maine coastline.
Coastal Flooding: Latest statements and warnings should be
monitored from the National Weather Service (again,
warnings/watches/advisories are linked to at left of this discussion)
for Coastal Flooding, as this has the potential to be a ravaging event
for some of us. The National Weather Service office in Upton, New
York, is comparing the magnitude of coastal flooding for Southern
Connecticut at the west end of Long Island Sound Sunday night (and
perhaps Monday if the storm stalls far enough south) to that witnessed
during the Perfect Storm of 1991. The biggest immediate concern will
certainly be for the west end of Long Island Sound, where fierce winds
will coincide with an astronomically high tide in the new moon cycle
Sunday night, pushing water up against these western coastal locales
and resulting in perhaps a major flooding event. Farther up the
coastline of Southern New England, vulnerability will center around the
10:20 PM Sunday high tide for especially east and east-southeast facing
locales. With an onshore wind and waves building to 25 feet offshore,
the threat for coastal flooding continues through Monday and Tuesday,
though magnitude will depend upon location of the storm, and therefore
the resultant wind direction and speed. This could end up being a
ravaging series of high tide cycles from Monday morning through Tuesday
evening for the Maine coastline and New Hampshire seacoast, and perhaps
the far North Shore of MA near Newburyport and Salisbury, where winds
may continue to gust to 50 or 55 mph even into Tuesday. If the storm
stalls a bit farther south, these effects will be felt farther south
along the Eastern Massachusetts coastline as well.
That's all for the early Saturday update. Yesterday's discussion here:
************************************************************
The storm I'm watching for later Sunday through Tuesday - when
considered with its intensity and duration, will rank as one of the
post powerful nor'easters in several years. Though this storm will not
be as ferocious as the Halloween storm of 1991 (a.k.a. "The Perfect
Storm"), it's likely to be located closer, and the duration will result
in significant damage to New England's coastlines. Over the course of
this discussion, I will outline what is known and what has yet to be
determined with this major storm. Through the weekend, I will update
this website as necessary if any information changes my view of how the
storm will transpire. 
Check out Coast Guard preparations from their site: http://www.uscgnewengland.com/go/site/778/
In the meantime, Friday morning dawned with heavy snow producing
white out conditions at times across Northern Maine as the storm that
swept across New England Thursday and Thursday night exits to our
east. The bands of heavy snow in Northern Maine will taper through
Friday, with scattered snow showers continuing through the mountainous
terrain, and a few sprinkles and flurries floating across the remainder
of New England at times Friday afternoon. Though plenty of lingering
moisture in the lower and middle levels of the atmosphere is allowing a
wide variety of clouds to linger over New England on Friday, winds
blowing from the west are sloping down the mountains and hills, and in
many downwind communities of Central and Eastern New England, this can
assist in bringing breaks of sun through the clouds. The storm
responsible for up to a foot of heavy, wet spring snow and over 10,000
power outages in Maine continues to move out across Nova Scotia, but
wraparound snow has been sluggish to depart from Northern Maine.
Gradually, this snow will move across the Canadian border and out of
the United States entirely.
Diminishing rain and snow showers and diminishing clouds will yield
a partly cloudy and cool night Friday night with breezes slackening a
bit, as well. Saturday's sunny start will blend with a few puffy
cumulus clouds during the afternoon, but will yield milder temperatures
as a small wedge of high pressure, or fair weather, moves over New
England. Meanwhile, all eyes will turn to the approaching major storm,
which will already have left a path of destruction in its wake. After
damaging thunderstorms and tornadoes through the Southern Plains,
including the Dallas/Fort Worth area, Friday afternoon and evening, and
another severe weather outbreak with numerous tornadoes in the Gulf
Coast and Southeast states Saturday, a ball of intense energy will roll
to the Mid-Atlantic coastline. This energetic disturbance will be the
driving force of our upcoming storm as it absorbs Gulf Moisture,
Atlantic moisture, and encounters a clash of airmasses from warm and
humid southern air with cooler and drier northern air. These factors
will combine to produce what's referred to as a "bomb" in the world of
meteorology - a storm that will strengthen rapidly off the Mid-Atlantic
coastline. Caught in a volatile jet stream pattern flowing quickly
from Georgia to Vermont, this storm will be pushed northward by this
corridor of storm-steering wind, drawing closer to New England as we
head into Sunday.
The first evidence of the impending storm will be quickly increasing
and lowering clouds Sunday morning, after a cool Saturday night thanks
to dry air still in place for most of New England. In fact, an
important player in the upcoming forecast is the center of cold and dry
air over Eastern Canada this weekend, that will be available to bleed
cold air southward across New England, and will do so through Saturday
night. It won't take long after the increasing Sunday morning clouds
for rain to follow suit, as it races up the Eastern Seaboard, with
heavy precipitation developing in Southern New England perhaps as early
as Sunday morning, then spreading north into the Northern half of New
England Sunday afternoon. Precipitation type will be mostly rain in
Southern New England, though the presence of cool and dry air may allow
for a brief burst of snow in many Southern New England communities, but
especially in higher terrain. Meanwhile, most of Northern New England
and even North-Central New England should be cold enough to start as a
period of snow, and perhaps accumulating snow through the interior.
Within about 50 miles of the coastline, any chance for accumulating
snow would be brief, given a deep developing southeast flow off the
milder ocean water.
It's at this point that all of the ingredients begin coming together
to rapidly strengthen the coastal beast, with its minimum central
barometric pressure dropping to around 29.10" and still falling
overnight Sunday night. This rapid strengthening will allow a fast
corridor of wind to begin feeding into the storm, and pushing through
the counter-clockwise flow around the storm center. On the north side
of the circulation, this will mean an east-southeast wind approaching
the South Coast of New England Sunday afternoon, blowing at as much as
30-40 mph by the end of the day from the South Coast of Connecticut to
Cape Cod, with gusts to 50 mph possible. Across the remainder of New
England, winds will also increase sharply as the wind field associated
with the storm expands markedly, with Sunday afternoon and evening
winds of 15-30 mph reaching through most of the six-state region. But
that's not the whole story for winds - they will continue to increase
Sunday night.
All the while, tropical Gulf moisture will be feeding north, and the
approaching storm will team with favorable jet stream winds aloft to
churn out plenty of precipitation. In Sotuhern and coastal areas where
a change to rain happens fairly quickly, rain will fall in torrents,
and the development of a weak coastal front - the difference between
ocean air and land air - may develop Sunday night, cranking out even
higher amounts near the front. In most of eastern Central and Southern
New England, in excess of 3 inches of rain is expected Sunday evening
and night, though near the coastal front, even higher amounts are
likely. Meanwhile, there's a good chance this will crank out as heavy
snow from Upstate New York east across Northern New England. At this
juncture, just how much snow would fall is still up for grabs, largely
because the path and timing of the storm is still uncertain...more on
this below. 
The heavy precipitation that falls Sunday night is sure to be
windswept, as the corridor of wind moving north continues to crank,
bringing winds of 45-60 mph from the east-southeast to coastal Southern
New England, with gusts to hurricane force possible. The question
regarding wind is how quickly these damaging winds march northward up
the coast of Southern New England. Both this question, and the
question of precipitation, revolve around the interaction of the
surface storm with its energetic upper level counterpart. That is,
while the storm is propelled northward by the jet stream winds Sunday,
at some point it will strengthen so much that the jet stream winds will
bend to flow around the storm, and while this will allow it to maximize
its strength, it also will result in a stall of the storm. At this
point, the question is where the storm stalls, and that's a matter of
fine tuning that will come as we near the event a bit more. For
example, a storm that continues moving north until stalling over
Southern New England on Monday would deliver the strong winds and
hurricane force gusts in a progressive blow to the coastline,
progressing up the coast from south to north overnight Sunday night,
and stalling as continuous damaging wind from the New Hampshire Seacost
to the southern coast of Maine. A stall just south of New England
would mean continuous battering of Southern New England with both heavy
rain and damaging wind. This detail is obviously an important one, but
it seems that either way - progressive or slower - all of New England
is in for gusty wind and heavy precipitation, and Southern New England
will be hit hard with wind Sunday late afternoon through Sunday night.
At this point, I actually favor a solution closer to the southern
scenario, with the low pressure center still south of the Islands of
Massachusetts as late as Monday evening after stalling south of us. If
my hunch on this is right, we're going to be looking at a very
dangerous and prolonged storm for Central and Southern New England,
especially, where the coastlines would be hit extremely hard.
This storm progression also will make a big difference on
precipitation amounts by Monday morning, as a faster progression will
spread more snow across Northern New England quicker, dropping a foot
to a foot and a half of snow on Northern New England by Monday morning
while a slower progression would shave about half a foot off of those
amounts, and bring little to the immediate Canadian border by Monday
morning! Again, at this point, a slower progression seems most
probable to me, though we still would see heavy precipitation spreading
across New England during the day Monday.
Regardless, this storm should not be underestimated for its effects
on the marine community. Storm force winds and hurricane force gusts
mean all mariners must be in port by Sunday afternoon to avoid
life-threatening conditions. Waves will build to over 20 feet Sunday
night into Monday. Coastal residents couldn't have worse timing, as we
enter some of our highest tides of the year with a New Moon Spring Tide
cycle producing 11 to 12 foot tides. This, coupled with persistent
onshore flow through Tuesday, makes coastal flooding a virtual
certainty at almost every high tide cycle from Sunday evening through
Tuesday night. Exactly what communities get hit, and whether this is a
moderate or major coastal flooding event, will depend heavily upon wind
direction, and that, as alluded to above, depends heavily on where this
storm stalls out. For now, coastal residents who are prone to coastal
flooding, even if only during significant events, should prepare for
flooding. If a major event shapes up, and especially if the slower
solution verifies, evacuations may be needed on Monday. Mariners in
particular may wonder why I'm calling this a northeaster if winds are
east-southeast. Though winds begin with a great blow from the
east-southeast Sunday night, if the storm center stays south of us,
winds will shift to blow from the northeast during the day Monday, and
remain from the northeast Tuesday. Two of the three days are spent
with northeast winds - and truly the winds will probably remain
northeast through most of the week - and that's the reason for the
nomenclature.
Marathon Monday depends heavily upon where this storm stalls, too.
A stall south of New England, as mentioned above, would keep heavy rain
and heavy wind across the entire race course. A stall overhead would
allow winds to relax in Southern New England and rains to shift north
as rain and snow to Northern and Central New England. I suppose
optimists should hope for this farther north progression to verify,
though that would mean south coastal Maine and New Hampshire would be
under the gun for heavy precipitation and coastal flooding.
The effects of this major and slow moving storm will linger through
most of the week. Tuesday will bring heavy bands of precipitation to
New England again, focused especially across Northern and Central New
England, with colder air gradually draining south from the Eastern
Canada high pressure cell, changing many areas to snow, though
accumulating snow would likely be contained to Northern and Central
areas thanks to above-freezing temperatures in Southern New England
Tuesday afternoon. I wouldn't expect nice weather to return in any big
way at all next week, as the big storm leaves behind a very big
"trough," or dip in the jet stream, that will favor new energy and cool
air continuing to drop over the Eastern Seaboard. In fact, another
much weaker storm will develop in this trough later in the week
(Thursday into Friday) though will probably stay south of us.
Nonetheless, with energetic disturbances still dropping in aloft, the
chance for precipitation remains, along with plenty of clouds, through
the end of the week.
I will issue updates as needed this weekend for this storm, but I
hope I've conveyed clearly above that we're dealing with a major storm
with major negative effects. The combination of its duration and
intensity, precipitation types and prolonged onshore flow with
propensity for coastal flooding and the impact on the marine community
- keeping many in port through a good part of the week - along with
beach erosion that may compromise houses if the slower, southern
solution verifies, all are my reasoning for saying this storm has the
potential to rank among the top 5 storms in the past several decades.
Technical Discussion: I plan on updating the technical discussion in snippets over the weekend to give an idea of my thoughts.
Matt
Matt's Technical Meteorological Discussion: Updated Saturday, April 14 at 11:30 AM
12Z Sat NMM just coming in and now shifting much farther south than
previous runs. This is a significant trend toward the
ECMWF/GGEM/Canadian Ensemble Guidance and tho the 12Z GFS is not in
yet, I expect it will likely follow suit. If you've read the General
Wx Summary yesterday or this AM you know my preference is to keep this
storm farther south, which keeps east coastal MA under the gun - at
least the NShore - thru the NH Seacoast and Srn ME thru Monday. This
also will have huge implications on closing the window of optimism for
a dry slot in Ern MA for the Marathon. Wouldn't rule out that
possibility yet, but if the Srn solution does indeed verify - even with
the low as far north as the SCoast of NewEng we'd still find well
developed onshore flow to saturate the lowest several thousand feet of
the atmosphere with bands of ocean enhanced rainfall. Will be
interested to see how the 12Z GFS comes in, but to find such a shift in
the NMM to the very consistent foreign models certainly is a huge sign
that should not be ignored. Those following a northern solution for
the low need to reopen the southern solution window and allow room in
forecasts for the implications of such a track. Those believing in a
more southern stall of the storm (myself included) this is a step in
the right direction for the forecast (the wrong direction for the
public) but of course there is a lot of time to go.
Matt
Monday's Discussion
1:10 PM: After two days of plenty of diurnal Cu and cool temps, sunshine is
more abundant than expected early this AM and temps responding, so had
to bump numbers up a few degrees for this afternoon. Winds slacken a
bit overnight but even 5-15 mph sufficient to produce chills in the
teens with dry air allowing falling temps into the 20s most areas.
Tuesday's llvl temps are actually progged to be colder than Mon, so may
see numbers coming back just a shade cooler, tho less wind shud produce
a comparable feel. Sfc rdige axis crests overhead on Wednesday, and
this brings nearly neutral horizontal thermal advection along with a
light wind. Aloft, the persistent upper low over extreme Eastern
Canada pulls northeast and well east of Newfoundland.
The shift in this pattern aloft allows for a more progressive upper
air pattern. This effectively cuts off our protective northwest flow,
and with a pinched off ridge over Central Canada as part of a highly
amplified omega block, troffing locks over Nrn NewEng and Ern Quebec,
meaning cold air keeps coming south in the lower several thousand feet
of the atmosphere, locked in by confluent flow east of ME. Warmer air
will try to spread NE out of the Ohio Valley later Wed, resulting in
increasing clouds. Of more importance, of course, is the strong
Pacific energy coming into the NW US early this week, traversing the
country quickly in fast westerlies midweek, and amplifying as it
approaches the NE US trof by later Wed and Thu. This system comes not
only with moderate vorticity, but also carries a moist and warmer
airmass owing to its Pacific origins. Additionally, an active
subtropical jet will offer at least modest input to this storm on its
southern flank. This additional warm and moist advection will aid in
shifting focus from primary low in Great Lakes to new developing
secondary low off Mid-Atlantic coastline. With cold air wedged in
NewEng, sfc low is likely to favor a track S of NewEng, and the airmass
will be dry enuf to stay cold upon saturation, and most certainly looks
cold enuf for snow. Of course, one critical component is storm track
in this scenario. With such dramatically conflicting airmasses,
there's likely to be a rather sharp rain/snow line on the NW side of
the circulation, tho the NE side may have a small mix area where midlvl
warmth rides farther north but northeast wind holds in ageostrophic
wind component. Still, for the interior of even Southern NewEng this
has the potential to be a 6"+ snowstorm of heavy wet snow, that may
produce power outages this time in Srn NewEng. Tough to accept that
possibility logically, knowing we're a week deeper into spring and yet
contemplating a storm producing a swath of heavy snow farther SOUTH
than the last one, but the cold in place now is deep and thanks to the
combination of the persistent upper low aloft, and the building
anticylcone at the surface, is stubborn. Also of importance will be
the timing of the onset of precip. While last week proved full well
that this was not important for areas deep enuf into the cold air,
diurnal effects certainly did make a difference in Srn NewEng last
week, and will again this week, tho perhaps more of Srn NewEng will be
more squarely into the cold air this time around, making it more of a
factor farther S. What I mean by this is that a strong April sun angle
can have a big effect on temps - especially in lower elevations - and
this would influence ptype right from the start. An early start means
less diurnal effects before dynamic and evaporational cooling takes
over, while a delayed start increases boundary layer temp and makes
pure snow at least a bit more of an effort, creating elevation AND
north/south dimensions to the rain/snow line. Again, deeper into the
cold air - which may even simply mean interior Srn NewEng this time
around - this will be less of a factor.
The storm should be out by later Thu ngt, and Fri looks like a windy
and cool day. But for the weekend comes a very impressive upper level
low, barrelling E in the jet stream flow with a well amplified trof
that has shown very strong indications of being an efficient precip
producer in the Ensemble guidance for two weeks! This disturbance will
amplify sufficiently to tap the gulf of mexico full bore, meaning
inches of rain will be possible Sat Ngt/Sun, and on top of snow, this
would result in flooding for Srn NewEng on Sunday. Of course, that
comes just a day before the Boston Marathon, meaning conditions could
be sloppy, especially in the fields of Hopkinton where preparation for
the race takes place.
Farther down the road, troffing persists into the last week of
April! This will keep temps below to much below normal for the week of
the 16th to 20th of April, then near or slightly below normal on
average (a day or two may exceed normal) the final week of April.
Plenty to watch carefully - an amazing winter pattern continues in the middle of spring!
Matt
