March 12-15, 2023 | NE / Mid-Atlantic Winter Storm

[StretchCT]

Not seeing major differences at 500mb with the upper low.  Was suspecting that the upper system is moving slower, trending west like they sometimes, even oftentimes do. Poc is right about that parcel though.  It looks out of place.

Even crazier is that at 42hrs, the low is further west . 

Culprit at 850? It's further east for some reason. But it too starts off closer to the coast at hr 42. 

I don't see it chasing convection - it's definitely that vort max causing this. 

 

[StretchCT]

GEFS ticked a bit SE too

 

[StretchCT]

Model comparison with that vort max

[StretchCT]

WPC from 22Z today.  If anyone has the winter products from WPC can you post them.  My version looks funky - not even a map.

[MaineJay]

Not sure if models still chase convection.  

[MaineJay]

10 minutes ago, StretchCT said:

WPC from 22Z today.  If anyone has the winter products from WPC can you post them.  My version looks funky - not even a map.

72 hour maps 

>4"

>8"

>12"

 

[CryptoWeather]

Where is the Cras model when you need it?

[PA road DAWG]

39 minutes ago, MaineJay said:

Not sure if models still chase convection.  

Yea. This is a tough one.  Getting winter storm juno vibes 

[MaineJay]

18 minutes ago, PA road DAWG said:

Yea. This is a tough one.  Getting winter storm juno vibes 

Funny, I thought that too. Been checking the analogs, while Juno isn't in there, #8, the 2013 storm has a similar distribution. Incidentally, I joined the AccuWeather forums after that storm.

Edit, actually, I missed it, it's in there. #12

 

[Poco]

18z navgem track 

 

[MaineJay]

Meso showing a deeper, and more east system than the NAM and FV3 had it.  

 

RGEM was closest to analysis.

[MaineJay]

NAM should come west of it's 18z run I'd think.

[NEPAsnow]

it certainly looks like that to me as well

[MaineJay]

HIRES FV3 is trending the right way.

[MaineJay]

Need the western vort to be dominate. NAM is feeling it's way, can't decide.

 

[MaineJay]

Hard for the models to figure out where low pressure develops out of the SE convection.

[StretchCT]

ugh -gfs even more SE of the 18z run.

[LiveWire_13]

2 hours ago, StretchCT said:

ugh -gfs even more SE of the 18z run.

Well that's not an antithesis of the latest NAVGEM run...
We're slowly getting to the point of favoring Mesos over Globals. But before we get there, it may not be a bad idea to organize the models into camps and see where the trends favor as game time approaches. Scientific? No. More effective than commenting on individual models? Yes.

[MaineJay]

EFI has been fairly consistent in it's placement of anomalous snowfall, if anything, it's sagged south.

[MaineJay]

GYX is pretty bullish. I think there's a real chance it hits a wall, and it doesn't move poleward enough.  There's isn't the dry feed from the NE, so that'll help QPF, but with not with temps.  

Quote

LONG TERM /MONDAY NIGHT THROUGH SATURDAY/...
Overview...

A significant winter storm arrives Monday night and impacts the
region into Wednesday. The system gradually moves away midweek,
allowing high pressure to return on for Thursday and Friday.
Another system is then possible next weekend.

Details...

Low pressure moves off the Carolina coast Monday afternoon and
undergoes bombogenesis as it tracks northward toward Cape Cod
Monday night and Tuesday. The low then meanders in the Gulf of
Maine before slowly departing on Wednesday. In terms of timing,
snow is expected to overspread southwestern NH Monday evening
and continue spreading northeastward through the overnight
hours. Snow then accelerates northward through much of Maine
during the morning hours on Tuesday as the low tracks northward
toward Cape Cod. Snow continues most of the day on Tuesday and
into Tuesday night, and only gradually winds down from southwest
to northeast from the early morning hours through midday
Wednesday.

Models have come into general better agreement on the track and
progression of this system. There remains some jumping around
of individual model runs among the global models and NAM, but
the ensemble means appear to be honing in on a low either over
or just east of Cape Cod. They have also come into good
agreement on a very strong low pressure center dropping to
around 975mb. While there remains some time for things to
change, a generally snowy solution looks most likely at this
point, with the locations of the heaviest snowbands still
uncertain at this time.

There are several storms in recent memory that this system
appears to be showing many characteristics with, including the
Blizzard of 2013 and the Blizzard of 2015. They both shared a
similar track near the benchmark at 40N/70W into the Gulf of
Maine, and then a slow exit to the east. Those systems are the
#1 and #4 snowstorms in Portland`s history, respectively.
However, what this system is lacking that those storms had is a
fresh supply of arctic air. Temperatures are expected to remain
near freezing for most of the storm across the lower elevations,
while the higher terrain stands the best chance to remain in
the upper 20s. With this marginal cool air, precipitation may
start as rain across southeastern NH and the southern Maine
coast Monday night before the heavier precip arrives.

This means that a much wetter and heavier snow is expected
across the lower elevations. This snow would be very difficult
to accumulate up to record-breaking amounts, but will still
bring impactful conditions. Scattered power outages will be
possible from the combination of wet snow and wind gusts of 40
to 50mph along the coast. Northerly wind gusts to 40mph are also
possible inland Tuesday night and Wednesday as the low slowly
exits the Gulf of Maine.

The highest snowfall amounts are expected to fall across the
higher terrain of southwestern and central New Hampshire, as
well as the southern foothills of Maine. In these areas, a
general one to two feet is currently forecast, but the highest
amounts will be determined by where the two heaviest snowbands
associated with the system overlap.

Northern areas may be too far removed from the system to see
the greatest impacts, which is why a watch has not been issued
for these areas. Any trend farther north with the system will
bring higher snow totals into the area, but at this point
confidence remains low in these areas.

In terms of the snow banding, with a system this strong and
dynamic, there is likely to be one band associated with the
initial low pressure center focused across southwestern areas
Monday night, and a second one to the northwest of the coastal
low pressure center on Tuesday. Where these set up the highest
snowfall amounts are expected, with snowfall rates of 2-4
inches/hr possible at times, making nearly impossible travel
conditions in these area. There is also the possability for
thundersnow in this second band. Again, the locations of these
bands remains uncertain at this time and will need to be
monitored closely right through Tuesday. The current snow
forecast does not reflect trying to pin down these heavier band
locations, so locally higher amounts are still possible
somewhere in the forecast area.

There is also a coastal flooding risk associated with this
system, but given the low astronimcal tides of the month this
threat is likely limited to possible minor issues and
splashover.

Main takeaways for the event...

- Starting Monday night through Tuesday morning from southwest
  to northeast.

- Highest snowfall amounts across the higher terrain of
  southern and central New Hampshire, and the foothills of
  western Maine. Lowest amounts across northern areas where
  there is less moisture.

- Uncertainty remains in the placement of the heaviest
  snowbands, with higher totals possible even into the lower
  elevations

- Snow gradually comes to end early Wednesday through midday
  Wednesday.

The low slowly exits the Gulf of Maine on Wednesday, with high
pressure arriving for Thursday and Friday. Another system is
possible next weekend, but at this points looks warmer and much
weaker.

 

[MaineJay]

Snow being reported in SW VA.

@1816 anything in your neighborhood?

[MaineJay]

BOX mentions that the GFS might be suffering from convective feedback.

Quote

Monday...

High amplitude trough/mid level low moves through the Gt Lakes as
secondary low moves off the mid Atlc coast. Deep layer moisture
begins to move in from the west ahead of the mid level trough, while
Maritimes ridge persists. The main focus for occasional light precip
will be across western MA/CT closest to best moisture and lift.
Ptype will be mostly rain, but snow across the Berkshires where
locally an inch or 2 is possible. Precip chances will decrease
further E as it runs into drier air and eastern MA may remain dry
through the day. Highs will range from the mid/upper 30s interior
high terrain to mid 40s in the coastal plain. Gusty E winds will
develop in the afternoon across the Cape/Islands.

&&

.LONG TERM /MONDAY NIGHT THROUGH SATURDAY/...
Highlights:

* Increasing confidence of a high-impact, multi-faceted coastal
  storm Mon night into Wed AM. Heavy dense/wet snow
  accumulations, greatest in the terrain could create snow load
  issues. Strong to damaging wind gusts, hazardous to
  potentially dangerous marine conditions, minor coastal
  flooding and beach erosion are all additional concerns.

* Drier weather returns Thursday into Friday, then unsettled weather
  possible Fri night into Saturday

Details:

The long-term portion of the forecast was entirely focused on the
multi-faceted winter storm slated for Mon evening into early
Wed. Thus for most of Wed and beyond, NBM was used with nil
modification. More details follow.

Large-Scale Trends/Evolution and Uncertainties...

It is admittedly still a complex evolution, as a potent closed low
aloft digs south of Long Island and helps slow and pull leftward a
consolidating and likely rapidly deepening secondary (or possibly
tertiary?) sfc cyclone late Tue into Tue night, then appearing to
pull away from SNE overnight Tue-early Wed.

Most of the 00z ensembles and deterministic NWP did trend a little
bit cooler due to a slight eastward storm track adjustment. Where
this consolidating and rapidly strengthening coastal storm develops
and evolves is still significantly uncertain but will have
substantial implications on expected impacts, and particularly in
the coastal plain of RI and MA and into Cape Ann, Cape Cod and the
adjacent waters. NAM and the Canadian GEM appear to be closest to
the coast late Tue/Tue night at around 980 mb; the ECMWF is a little
further east just offshore of the Outer Cape; on the other hand the
GFS shows an elongated trough but with a rapidly deepening cyclone
over the warm Gulfstream waters Tue AM, then rotating it back
westward into the lower Gulf of Maine thru Tue and settling about 20-
30 nm east of Cape Cod at 970 mb overnight Tue-early Wed! It
wouldn`t surprise if the GFS rapid deepening is in part from latent
heat/convective feedback as it is over the Gulfstream waters early
Tue. As mentioned, it`s a very complex evolution that models
struggle mightily with.

Precip Types/Snow and Rain Amounts...

Continuing a theme in messaging specific to this storm,
accumulations that do result will not only hinge on the storm`s
track, but will also have a significant elevational component. In
addition, snow to liquid ratios probably will not be around 10:1
until the cooler air comes in Tues night. What this will translate
to is dense, water-loaded snow capable of snow load problems,
especially where snow amounts are expected to be the greatest in the
terrain.

Because temperature profiles were a little bit colder around Tue and
Tue night, snow amounts were increased and most notably in the lower
elevations. We`ve expanded the Winter Storm Watches to now include
all of northern CT, the entirety of the CT Valley, northern
Providence County in RI and into Middlesex and western Essex
Counties in MA.

While temperatures in the terrain of the Berkshires and northern
Worcester Hills will support snow at onset, enhanced east flow off
the waters Mon night into at least part of Tue should force most
areas to be plain rain.

One source of uncertainty with the forecast is timing how soon the
cooler air, initially over northern MA and the terrain, will
shift/collapse ESE into the lower elevations and into the cities. We
did side to bring cooler air sooner than the warm NBM following
trends in the 00z guidance, with northern CT, northern-central RI
and eastern MA changing from rain to wet snow as soon as Tue aftn.
Precip then remains as all snow and perhaps locally heavy snow for a
time across all areas, even the coasts, Tues night before the low
pulls away early Wed.

Winds/Gusts...

E winds increase Monday night over land and water Mon night. NE
winds on Tues then increase markedly due to presence of a strong
isallobaric rise/fall couplet and progged 925 mb jet of up to 65 kt
in most models, which lashes the coastline Tues aftn into Tues
night. It is worth noting the GFS jets are considerably stronger
with 950 mb winds of 60-65 kt and up to 75 kt at 925 mb!

The most intense of the winds takes place along the coastline later
Tues aftn into Tues night, with NE-N winds of up to 60 mph. Further
inland, NE peak gusts around 45-50 mph seem possible, lower in the
CT Valley. This will add to the risk for tree and powerline damage
where dense snow weighs on trees and powerlines.

We have hoisted a High Wind Watch for the North Shore, South Shore
and Cape Cod (excluding the Boston coast). Additional wind headlines
may be needed later further in the interior and/or lumped into
winter storm headlines.

Coastal Flooding/Beach Erosion...

Astronomical tides are low (less than 10 ft MLLW at Boston) which
will limit the threat for significant coastal flooding. However, the
long duration of this event will impact three tide cycles, from
Monday night into Wed morning. The Tue night/early Wed morning may
be the tide with the highest water levels, given the previous two
tide cycles likely will not completely drain seaward. Storm surge of
1.5 to 2.5 ft are projected with each tide, with low prob of 3 ft
storm surge possible. Also the low astro tides will help to preclude
significant erosion, but this may be offset somewhat by waves
pounding the coastline for three tide cycles. Greatest concern for
erosion will also be the late Tue night/early Wed tide cycle. As of
now, moderate to high prob for minor coastal flooding/erosion, with
low prob for moderate coastal flooding/erosion late Tue night/early
Wed tide cycle. A coastal flood watch may be needed if this threat
increases with time.

 

[MaineJay]

SE radar.

[MDBlueridge]

21 minutes ago, MaineJay said:

SE radar.

Plenty of juice! 

[MaineJay]