January 6-7, 2024 | NE / Mid-Atlantic Winter Storm

[MaineJay]

GYX

Quote

LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/...
New year, new pattern? Well it does look like some changes are
in store at 500 MB over the extended forecast, with a trend
toward more amplified flow /although may be more in the srn
stream, which may get separated from the nrn stream/, more
blocking in the arctic /which will push colder air equatorward
to some degree/, and a -NAO /although it may not last long/.
Anyway, this should trend toward a colder period in the first
couple weeks of January, although nothing that falls too far
below normal for any length of time. The separation of the srn
stream to our S, will tend to keep any significant and dynamic
troughing, and associated sfc lows to our S through next weekend
/although close enough that we shouldn’t completely write them
off yet/, but for now systems around Thu and Sunday tend to be
more showery with only chance POPs.

Tue night and Wed look mainly dry and mostly clear, although
could see some SHSN in the mtns, especially during the day Wed,
as weak low passes to our N. Lows Tue night will range from
around 20 in the mtns to the mid 20s in the S, with highs on Wed
in the mid 30s N to the low 40s S. A southern stream system
tracks NE out of the SE coast and begins to phase to our SE, S
of Nova Scotia, which is too late and too far away to bring us
more than cloudy skies. Could see a few SHRASN on Thu as the 500
MB trough passes through but that seems to be about it. Highs
on Thu will be a little cooler due mainly to the clouds and run
mostly in the 30s.

Initially NNW flow aloft and eventually ridging should provide
fair wx Fri and Sat, although it will be colder with highs
mostly in the mid 30s to 30s N-S both days and overnight lows
from around 10 in the mtns to around 20 in the S. That ridge
should hold on Sunday and Sunday night as deepening sfc low
passes to the S of New England and NS. The GFS show less respect
for the strong high to the the N and could produce a little -SN
or SHSN in the S, while the Euro keep things mostly dry. Stay
tuned.

 

[MaineJay]

Important to remember that we are in a lead time where trends aren't really "linear", where different parts are still going to shift around a bit more stochastically.  That said, over multiple runs, we might start to see pieces baby stepping into their position, with some still going back and forth.

BOX

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.LONG TERM /TUESDAY NIGHT THROUGH SUNDAY/...
Key Points:

 - More active pattern taking shape through next weekend.
 - Offshore low may bring some light rain/snow showers Thu.
 - Stronger coastal low Sun/Mon likely brings rain/snow.

Medium range ensembles show the pattern is expected to become more
active over first week of 2024, indicative of strong El Nino as
several southern stream short waves travel from Gulf of Mexico to
the East Coast. Each of these should feature plenty of moisture but
also warmth, so it`s a matter of how close the surface lows track to
the coast and whether or not we have enough cold air in place to
support snow. Those important details will only be able to be worked
out a few days in advance, but we certainly are looking at some
chances for wintry weather, something we haven`t seen so far this
winter.

Thursday:

We continue to have increasing confidence that low pressure will
track offshore and only bring a glancing blow to SNE, at least to RI
and southeast MA. Models are in good agreement that upper trough
will maintain too much of a positive/neutral tilt due to a lack of
downstream ridging which prevents the surface low from tracking
closer to the coast (it actually does so too late for us once the
system approaches the Maritimes). However, temperatures should cool
once the low passes by which could result in a changeover from light
rain showers to light snow showers Thursday night, but we`re not
expecting much if any accumulation.

Sunday - Monday:

Next southern stream trough looks to be more potent and should
support a stronger low pressure system emerging from Gulf of Mexico.
Its ultimate track is dependent upon complex interactions at mid
levels, namely how fast and where upper trough closes off, which is
tied to strength of upper ridge developing across Midwest as well as
presence of lower heights over Maritimes. We probably won`t begin to
see more definitive trends until at least 3-4 days ahead, but for
now ensemble probabilities suggest a better potential for at least
some accumulating snow inland and possibly closer to coast as well.
Temperatures aloft should be cold enough to support snow but it`s
the surface temperatures which are more marginal and will be key to
whether or not we see accumulations. Stayed close to NBM for now
which offers best compromise but it may end up being too warm. We
did note that the 00z GFS shows fairly cold solution, one that
results in more snow for SNE, but is an outlier compared to its
ensemble members. It also has most of the precipitation offshore or
near south coast, more aligned with rain in the milder air. For now,
we`re confident that low pressure will be somewhere off the SNE
coast late next weekend but less so with regard to precipitation
type and potential impacts.

 

[Rush]

1 hour ago, MaineJay said:

Important to remember that we are in a lead time where trends aren't really "linear", where different parts are still going to shift around a bit more stochastically.  That said, over multiple runs, we might start to see pieces baby stepping into their position, with some still going back and forth.

BOX

 

I was hoping I'd wake up early enough to get in here before @MaineJaytold me why it wasn't going to snow.

[MaineJay]

1 hour ago, Rush said:

I was hoping I'd wake up early enough to get in here before @MaineJaytold me why it wasn't going to snow.

I'd actually favor areas around the Mason-Dixon line currently with a narrow, but potentially significant snow axis.  The subtle stream interactions are going to play havoc with the models and emotions.

 These southern systems will have the juice, it's track, as well as just how the cold/dynamics feed into it are impossible to figure out right now.

 That said, there's a lot to like, especially considering the backdrop.  I mean, in the desert, the thirsty one seeks out any oasis to slake their thirst.

[MaineJay]

Ukie hugs the coast. 

These are l ordered least to most confluence near the crown of Maine.

Now that's just one part. Trailing energy is also handled much differently. ECMWF is plowing shortwaves West-> East, the other 3 have varying degrees of phasing with the trailer, and/or with the northern stream.  Not s ton in the Ukie, but it does have that little guy near lake Michigan which likely helps the low hug the coast (also responsible for less confluence).

 Don't be surprised if model spread increases over the next few cycles.

[Wtkidz]

Well lots of thoughts from Sterling. Bottom line is they expect some wintery percipatation. What type(s’). Is to be determined.

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LONG TERM /THURSDAY THROUGH SUNDAY/...
High pressure over the Upper Midwest U.S. will build southeastward
into the region Thursday through Friday. Low pressure offshore of
the Outer Banks should remain offshore, as it intensifies and moves
northeast into the northwestern Atlantic Ocean. The interaction
between the building high and the offshore low will create a gusty
northwest wind Thursday and Thursday night. Dry conditions and
seasonable temperatures are expected Thursday through Friday. By
later in the day Friday into Friday night, the high pushes to the
East Coast. Winds will diminish and become more variable Friday
night. Highs Thursday will be near 40 to middle 40s east of the Blue
Ridge and upper 20s to upper 30s west of the Blue Ridge. Highs
Friday lower 40s east and upper 30s to near 40 west.

Let`s take one step back in time and look at the period of Friday
night then look ahead in time to Saturday morning. During the same
time that the high pressure pushes to the East Coast late Friday, a
cold front is expected to drop southeast across the Eastern Great
Lakes Friday night and eventually get washed out Saturday morning as
it moves into our region from Pennsylvania. A separate area of high
pressure is forecast to build southward from central Canada behind
this front and push into the mid-Atlantic region by Saturday
morning. This high should bring some reinforcing cold air into our
region, which could support wintry precipitation across any part of
our region Saturday afternoon through midday Sunday. It is during
this time, the middle of the weekend, when low pressure is expected
to move across the Carolinas, near the Virginia Tidewater and
intensify nearshore the mid-Atlantic region. Deterministic model
consensus of the GFS, European, and Canadian has the potential for
moderate to heavy precipitation across much of our region Saturday
afternoon through early Sunday. Depending on which model you
believe, may give you slight variations of what could happen. To
break it all down, there are similarities between the GFS and
Canadian in which the low intensifies and tracks across inland areas
of the mid-Atlantic Coast and across the Delmarva. The European
intensifies the low as it tracks farther to the south across the
Outer Banks and rapidly intensifies it over the offshore waters
of the Virginia Tidewater. Either track has the potential to bring
moderate to heavy wintry precipitation to our mountains, the
Shenandoah Valley and central Maryland, while a mix of snow and rain
could occur further east with moderate to heavy rain near the
Chesapeake Bay and southern Maryland areas. Stay tuned to the
forecast through the workweek. We will be closely monitoring this
low pressure system during the week.

In terms of temperatures Saturday, they could be similar to Friday
with seasonable temperatures possible.

As for Sunday, precipitation of all types east of the Alleghenies
should taper and come to an end, as the low pressure system moves
offshore. A gusty west to northwest wind behind the departing low
could still serve a purpose of producing upslope snow showers in and
just west of the Alleghenies. Sunday`s temperatures should
reach the middle 40s with middle to upper 30s in the west.

 

Edited January 1 by Wtkidz

[Wtkidz]

6z gfs.

[JDClapper]

29 minutes ago, Wtkidz said:

6z gfs.

@PA road DAWG .. Jan '16? 😭

[Penn State]

00z Euro showing some of that suppression risk.. Did so in 2016 as well if I remember correctly. Not sure this is a direct analog, but the confluence discussion is for sure. 

[Snowadelphia]

5 minutes ago, Penn State said:

00z Euro showing some of that suppression risk.. Did so in 2016 as well if I remember correctly. Not sure this is a direct analog, but the confluence discussion is for sure. 

One man’s suppression is another man’s jackpot.

[TLChip]

Lets see which way this trends over the next 3 days...

 

 

GEFS Trend

 

Euro trend

Edited January 1 by TLChip

[MaineJay]

Less spread at H5 in the EPS than the GFS. Not saying it's correct, just that the suite as a whole is expressing it's confidence, but ensembles can be under dispersed at times.

 

[Pghsnow]

6z EPS

[Penn State]

The good ol’ Weather Channel with their initial forecast. 

[JDClapper]

0z tracks, and 12z/0z "trend"

 

[Penn State]

Our NOAA person at CTP.. useless. 

[JDClapper]

Tried outlining the west/east clusters of 0z EPS to give a "cone of uncertainty" at this juncture.  There's a slight westward preference, so a line right down the middle isn't necessarily the best probability, at this time.

[JDClapper]

WPC probs of 2"+ of snow/sleet.  These are generally a suite behind, so I'd considering this a 12z summary, imo .. (updated at 11:56pm)

 

[PA road DAWG]

53 minutes ago, JDClapper said:

@PA road DAWG .. Jan '16? 😭

Hahahaha I was literally just going to say that! 

[PA road DAWG]

16 minutes ago, JDClapper said:

0z tracks, and 12z/0z "trend"

 

The animated image shows the confluence flexing its muscles up over Nova Scotia 

[PA road DAWG]

13 minutes ago, Penn State said:

Our NOAA person at CTP.. useless. 

Haha ok 👍🏻 

[Penn State]

15 minutes ago, Penn State said:

Our NOAA person at CTP.. useless. 

I don’t know if anyone’s seen this online.. but this meme is how I feel the guy at CTP is.. 😂 

[HVSNOWSTORM]

Hopefully the models don't keep pressing south or this will be a NYC on south event. Like 2016 but with less extreme accumulations. Def would like to see a more juiced up storm and more stream interaction to counter that confluence and quick approaching next system. 

 

Hopefully if it does end up more south, guys like me PARD, JDC, can still get a 2-6" snowfall, because it would be pure fluff, not that heavy slush garbage we had last year ( for the little we did get). That in itself would be a refreshing welcome.

[Penn State]

As the 12z model runs approach.. some CTP and WPC graphics.. Chances increasing. 

[Penn State]

GraphCast still looking solid..