February 12-13, 2024 | Winter Storm

[Rickrd]

2 minutes ago, Uscg Ast said:

@MaineJay @BuckeyeGal @Mainiac

I am all in it for this! LETS GO!

[Doorman]

[LiveWire_13]

49 minutes ago, Doorman said:

I'm trying to figure out which blend of models they're using, but this looks like a watered-down Euro more than anything else I can tell. Obviously there's more to forecasting than repeating model output, but it almost feels like NWS is sticking head in the sand on this one.

[MaineJay]

GYX

Quote

LONG TERM /MONDAY NIGHT THROUGH SATURDAY/...
The focus of the long term period will be an area of low pressure
tracking from the DelMarVa to southeast of Cape Cod Tuesday and then
quickly exiting south of Nova Scotia Tuesday night. This system will
spread snow into southern NH late Monday night and into coastal
Maine Tuesday morning and will last for the better part of the day.
The northward extent of accumulating snowfall as well as the
potential for bands of heavier snowfall rates remains in flux while
confidence is increasing that at least southern NH into far SW Maine
will see impacts from 6 inches or more of snow. Wednesday will be
colder and blustery followed by high pressure arriving Thursday. A
couple of fast moving waves will bring chances for snow showers
Friday and over next weekend.

The upper level feature that will lead to our coastal system Tuesday
is currently over New Mexico and will trigger multiple rounds of
severe convection along the Gulf Coast states over the next 48 hours
or so. Global models and ensembles have been relatively consistent
in this upper wave crossing the Mid Atlantic Monday night with a
deepening surface low tracking near the 40N/70W benchmark Tuesday
afternoon. Where models diverge is the northward extent of snowfall
with some model solutions keeping the northern half of the area
mostly dry while others bring light snow to the Canadian Border.
There is also variance in the axis of highest QPF and resultant
snowfall due to the potential for snowbands to develop on the NW
side of the system. There are signals for a band of Fgen
forcing to push into southern NH and coastal SW ME Tuesday
morning with a secondary band of Fgen forcing displaced further
NW into central NH and interior SW Maine early Tuesday
afternoon that could produce areas of heavier snow.

Overall, the 00Z ensembles show a slight northward shift in moisture
with mean QPF of 0.75" to 1.0" near the NH/MA border decreasing
to around 0.5" from KCON to KPWM and then decreasing sharply
into the mountains. At this time there likely looks to be travel
impacts Tuesday from snow covered roads. Additionally, thermal
profiles will be near or just below freezing where the heaviest
snow may fall bringing the potential for downed limbs and power
outages across southern NH into far SW Maine. Have gone with a
Winter Storm Watch across Southern NH expanding northeastward
into York County Maine where confidence is greatest for 6 or
more inches of snow. If there continues to be slight northward
shifts over the coming forecast cycles then it is likely this
Watch will need to be expanded northward while the majority of
model solutions continue to keep the mountains out of the
heaviest snow.

🤷‍♀️

[Wtkidz]

Current radar

just fyi.

 

 

[Wtkidz]

36 and  48 hr forecasted surface maps.

 

[Wtkidz]

LWX. Yes  no snow for me but the  mountains might…..

Colder air begins to advect in from the north and west heading
into Tuesday morning as the surface low pulls offshore and the
upper-level low pivots overhead. Dynamics under stronger bands
of precipitation to the northwest of the surface low and under
the upper-level low will also contribute to cooling temperatures
through the column. This will likely cause precipitation to mix
with and change to snow over the Appalachians, as well as the
higher elevations west of I-81, over northern Maryland, and
along the Blue Ridge Mountains. The rate at which this
changeover occurs will dictate how much snow falls, but given
warm boundary layer temperatures before the changeover, as well
as weakening dynamics and dry advection during the cold air
intrusion, snowfall amounts have trended down on the overnight
cycle. A coating to a few inches is most likely for the
aforementioned areas, with little or no snow expected elsewhere.
If the stronger/further south guidance were to verify, then
several inches of snow would be possible particularly over
western Maryland Tuesday morning. This bears close monitoring
given its timing coincident with the Tuesday morning commute.

 

[Undertakerson2.0]

8 hours ago, Wtkidz said:

We offered it hush puppies and sweet tea.  What more can we do?

Seriously under appreciated post. Well played

8 hours ago, LongIslanGurlllll said:

Tito’s and a smoke?

This ain't a firing squad - though it seems like it at times. 

7 hours ago, StretchCT said:

Meh - wrongo as usual.

 

7 hours ago, StretchCT said:

Wish it were true... but according to Snobal

 

See? Told ya

7 hours ago, Rickrd said:

And alas. SREF HUMPS IT NORTH!

A good time to remind folks that SREF will most likely mirror the NAM run prior to it, so this is reflecting the 00z NAM to a large extent (SREF is essentially, an ensemble of the NAM)

7 hours ago, JDClapper said:

I saw JB tweet that the AI models have mostly been further south than the consensus with this one so far .. so will be a decent test on if our robot overlords can do better than the legacy models

He's just glad he doesn't have to keep mentioning some Tazmanian Model or the "new" North Korean model or  some such, and what it shows.

6 hours ago, MaineJay said:

Some important shortwaves are moving through the Yukon.  Kinda the last pieces to the puzzle.  It looks like the impulse near great slave lake helps with the cold push at 850mb just ahead of the storm.  Sometimes with satellite gathered data, very northerly features are actually a bit further south than what the satellite "sees" due to the angle of view (parallax effect).   So I can see how the northern stream features from high latitude may come in a hair quicker than modeled. 

Geez, you are one WICKED NERD - but you know that right???

5 hours ago, RTC3-LAST CHANCE said:

When you posted that, which is great by the way, shows models have no clue at this juncture.

This is as messy as they come, as for precip types anyway. They get the general idea.

5 hours ago, Rickrd said:

We are T-2 days. Better start getting a Fu$king clue. 

Trust the NAM as of 12z today and all will be well. 

3 hours ago, Rickrd said:

I am all in it for this! LETS GO!

 

3 hours ago, Doorman said:

 

[Undertakerson2.0]

1 minute ago, Wtkidz said:

LWX. Yes  no snow for me but the  mountains might…..

Colder air begins to advect in from the north and west heading
into Tuesday morning as the surface low pulls offshore and the
upper-level low pivots overhead. Dynamics under stronger bands
of precipitation to the northwest of the surface low and under
the upper-level low will also contribute to cooling temperatures
through the column. This will likely cause precipitation to mix
with and change to snow over the Appalachians, as well as the
higher elevations west of I-81, over northern Maryland, and
along the Blue Ridge Mountains. The rate at which this
changeover occurs will dictate how much snow falls, but given
warm boundary layer temperatures before the changeover, as well
as weakening dynamics and dry advection during the cold air
intrusion, snowfall amounts have trended down on the overnight
cycle. A coating to a few inches is most likely for the
aforementioned areas, with little or no snow expected elsewhere.
If the stronger/further south guidance were to verify, then
several inches of snow would be possible particularly over
western Maryland Tuesday morning. This bears close monitoring
given its timing coincident with the Tuesday morning commute.

 

I like that they seem to keep it real. We are kind of threading TWO needles here - track and dynamics. 

The track part isn't all fired horrid (though not a beloved coastal) - the dynamics provide most if not all the cooling though, what with there being ZERO pre game cool let alone cold. 

[Undertakerson2.0]

Edited February 11 by Undertakerson2.0

[chaser915]

Before i went to bed around 11 last night NWS Albany even removed the HWO for my county- they changed it to a coating to an inch.

I get up at 5 this morning and we have a watch

 

[Undertakerson2.0]

Right now, I'd like to show you one of my favorite cartoons. It's a sad depressing story about people in the MidAtlantic who spend every moment of their lives during winter in pursuit of  modeled snowstorms only to have their hopes repeatedly mocked and crushed...

[Undertakerson2.0]

The professor glances at the timer that is keeping watch over his morning fare - his usual soft boiled egg cooked at the precise temperature of 193(F) and timed to a precise 3 minutes and 22 seconds (any longer it would be too rubbery, any shorter too runny for his taste). He smells the wafting aroma of a fresh pot of percolated Maxwell House while wondering why the local market stopped stocking Chase and Sanborn or even Hills Brothers. 

He looks at his latest map from the evening prior and mutters to himself "they used to believe me - back when I was somebody". 

The ding from the expired timer brings him back to the task at hand. He reaches down to pet his also aging Basset Hound (Maxwell) and says "c'mon boy, we'd better chow down - it's gonna be a loooonnggg day". 

[MaineJay]

22 minutes ago, chaser915 said:

Before i went to bed around 11 last night NWS Albany even removed the HWO for my county- they changed it to a coating to an inch.

I get up at 5 this morning and we have a watch

 

The struggle is real. 

 

[Undertakerson2.0]

[Undertakerson2.0]

[Undertakerson2.0]

The mid-level jet associated with the upper-level low will move
   eastward across Mississippi and Alabama during the day. The eastern
   edge of the mid-level jet is forecast to overspread the moist
   sector, which will create very strong deep-layer shear. Forecast
   soundings by 21Z from eastern Alabama into north-central Georgia
   have 0-6 km shear reaching the 80 to 90 knot range. In addition, the
   strong low-level shear already over the moist sector is forecast to
   be maintained, with 0-3 km storm-relative helicity values remaining
   in the 250 to 350 m2/s2 range. This shear environment will be
   favorable for severe storms, capable of producing wind damage and a
   few tornadoes. The severe threat is expected to continue through the
   late afternoon and early evening, as strong storms, associated with
   a potential for wind damage and a tornado or two, move northeastward
   into South Carolina.

[MaineJay]

I'm ready to hear more from this Mullinax, I'm digging this style. 

QPFHSD

Quote

...Northeast...

Days 2-3...

By Monday morning, the upper low over Arkansas will have been working in tandem with an upper ridge located over the Caribbean to foster a robust subtropical jet (STJ) over the Deep South. ECMWF ensembles centered on Tuesday 00Z show winds at the 850mb and 700mb levels to be above the 90th climatological percentile and tapping into a deep reservoir of Gulf of Mexico moisture. This will be the same moisture source that the 500mb low tracking into the Tennessee Valley Monday evening will direct northward into the Mid-Atlantic and along the Northeast coast. In fact, PWs over the Mid-Atlantic 06Z Tuesday 90th climatological percentile, so there is no shortage of moisture available. Farther north, confluent flow over southeast Canada and northern New England will support a 150kt 250mb jet streak and place its diffluent right-entrance region off the Mid-Atlantic coast Monday night. As a second 150kt 250mb jet streak over the Southeast approaches Monday night, a "kissing jets" setup will foster excellent upper level divergence along the Mid-Atlantic coast, allowing for a surface low to rapidly organize by early Tuesday morning while the initial low over West Virginia gradually weakens.

Recent trends in guidance have led to a more pronounced surge in southerly flow into southeast Pennsylvania, the Delaware Valley, and into the NYC metro area Monday night into early Tuesday morning. This has led to a reduction in probabilities for seeing >4" of snow in these areas. What this has done, however, is flexed the robust 850-700mb frontogenesis signal to align better over northern Pennsylvania, the Lower Hudson Valley, and through southern New England. Impressive vertical velocities coinciding with a highly saturated DGZ will foster ripping snowfall rates that could top 2"/hr, most notably from the Poconos and Catskills to southern New England Tuesday morning. Latest Probabilistic WSSI (WSSI-P) shows moderate-to-high chances (50-70%) for Moderate impacts from north-central Pennsylvania and the Lower Hudson Valley to eastern Massachusetts, implying these areas are likely to contend with hazardous travel conditions and disruptions to daily life. The Snow Amount and Snow Rate algorithms are the primary drivers in producing these probabilities. The WSSI-P even shows moderate chances (40-60%) for Major Impacts in parts of northern Connecticut, northern Rhode Island, and eastern Massachusetts on Tuesday, implying considerable impacts to daily life in these areas. WPC PWPF shows high chances (>70%) for snowfall totals >8" along the northern PA/southern NY border, in the Catskills, the Berkshires, and eastern Massachusetts. In fact, WPC PWPF sports moderate chances (40-60%) for snowfall >12 in the Catskills and Berkshires.

While these areas sport the highest confidence in expected impacts, there are still forecast details that need ironing out over the next 24 hours. On the northern flank of where the deformation zone sets up, a trailing shortwave over the Great Lakes will race in from the west, attempting to advect drier tongue of 700-300mb moisture into the eastern Great Lakes. In addition, such a robust area of frontogentical forcing over northern PA, southern NY, and southern New England would inevitably lead to some modest subsidence to the north. This is depicted quite well on the 07Z NBM 50th percentile snowfall totals, where amounts in Rochester could end up between 1-2", but southeast towards Ithaca, totals were around 9". This is a common occurrence from northeast Pennsylvania and western New York across southern VT/NH. Any additional shifts in track can still mean increases (decreases) in snow totals. Meanwhile, to the south, the recent trend of a northerly track would in fact make it tough for accumulating snowfall from Philly on north up I-95 to the NYC metro and the immediate coast of New England. However, ensemble guidance continues to show solutions where the deformation axis pivots over northern NJ, the NYC metro, and Long Island. By 00-18Z Tuesday, the ECMWF ensemble mean shows the low deepening from ~995mb to ~976mb, which would lead to a dramatic increase in winds as the low tracks off the coast Tuesday morning. There is still a scenario where as the low rapidly deepens, a burst of snow beneath the deformation axis and strong wind gusts could cause significantly reduced visibilities. While totals could still be minor, the combination of just moderate snow and wind gusts >40 mph may lead to notable impacts from blowing snow. The latest WSSI-P show 40-50% chances for Minor Impacts due to the Blowing Snow algorithm from the NYC metro to Long Island. Probabilities for Minor Impacts due to Blowing Snow jump to as high as 60-70% along the coast of CT, RI, and southeast MA.

Mullinax

 

[1816]

26 minutes ago, MaineJay said:

The struggle is real. 

 

[MaineJay]

Watching if the 0°C line at 850mb can push a little further south.  Currently it's ahair south of the NAM3.

 

[Undertakerson2.0]

AFDCTP

Two jet streaks, one over nrn New England, and the moving up
from the Deep South, will combine to produce strong lift over PA
for a good 12-18 hrs, despite the progressiveness of the
system. The 993mb sfc low over nrn WV will already be losing
it`s primacy Monday evening as a low forms over srn VA and the
DelMarVA peninsula.

PWATs do near 1" in the SE later Monday night, and 0.75" as far
N as FIG-UNV-IPT. Temp profiles as the precip moves in from the
south are favorable for rain for much of the area. Only the far
N will likely see precip start as (and stay all) snow. Rain is
far more likely elsewhere. The elevations will pick up more
snowfall than the valleys as the dynamic cooling of the column
will drop temps lower aloft than in the valleys.

The latest trends in guidance include a decided shift north in
the temp profiles favorable for snow. The sfc high does set up
NE of the area, and supplies some cold air into the system. But,
it is not that strong (1014mb at 00Z) and shrinks away quickly.

The best dynamics and lift for banded snow is now expected to
be north of I-80. However, latest ECMWF (00Z) and NAM (06Z) runs
make an extremely tight Omega/lift gradient over the far NW
with a drop off a cliff to the moisture and lift over Warren
Co. Many places will still get 1"+ of liquid eqiv south of I-80.
ENS plumes still yield a great spread in QPF (and snow)
throughout the entire region. So, the confidence to bump the
watch to a warning anywhere is just not there yet. In fact, the
shift north has put the srn tier of the watch in jeopardy. The
reasoning behind riding/continuing the watch for places S of
FIG-UNV-IPT is to allow for any waggle back to the south. A
shift back to the south with snow amounts high enough to warrant
watch/warning looks very unlikely, but this is just the first
waggle northward. The trend is not yet solid enough.

Edited February 11 by Undertakerson2.0

[Undertakerson2.0]

9z SREF coming in now. Out to Hr33/36 - looks just a tick south with the parent low (still over in TN/KY region) as pressure falls at Delmarva indicate the likely ensuing track

 

[Undertakerson2.0]

Ever so slight waggle back S with snow axis/coverage

 

[JDClapper]

[MaineJay]

Keep pushing those 850s south.