January 22-23, 2023 | Winter Storm

[MaineJay]

19 minutes ago, CandO100 said:

JD,

I see these modeled storm tracks you posted and I go “wow, this looks like a favorable storm track to bring snow to my area (Hagerstown, MD),” but then I look at NWS forecast and little to no accumulating snow is expected.

As a novice here, I’m guessing it’s the lack of cold air? We are missing the placement and strength of a cold high pressure in Canada needed for snow in my area? 

Antecedent airmass i a bit marginal, but if i have your location close, its 2-3 degrees from possible snow, per the NAM3km.  

The EPS also gives you a non zero chance of a little snow.

https://weather.us/forecast/4373719-williamsport/ensemble/euro/snow

[MaineJay]

30 minutes ago, HVSNOWSTORM said:

Gfs looks better too NAM like

A 25mb drop in 18 hours.

[SkiPatroller]

24 minutes ago, HVSNOWSTORM said:

Definitely a nice sizeable shift south and east with the snow.

Oh man, both of those bullseye Jiminy Peak at the 3-state point MA/VT/NY, where I serve on the ski patrol.  Please don't change!!

[MaineJay]

RGEM generally stayed its course.  Minor wiggles.

[CandO100]

36 minutes ago, MaineJay said:

Antecedent airmass i a bit marginal, but if i have your location close, its 2-3 degrees from possible snow, per the NAM3km.  

The EPS also gives you a non zero chance of a little snow.

https://weather.us/forecast/4373719-williamsport/ensemble/euro/snow

Thanks MJ. Yes, location is correct. Thanks also for the link. So there’s a chance!

[MaineJay]

At hour 36, the spread for the main trof increased from last run.

[MaineJay]

SREFs are pretty much 50/50 here.

[TLChip]

First time I checked my SREF's this year...

Euro

Quote

GFS

Quote

NCEP

Quote

 

Edited January 21, 2023 by TLChip

[MaineJay]

Northern stream seems a little more detached this NAM12km run. Might be a step in the wrong direction.

[JDClapper]

Some 0z ICON and GFS

[JDClapper]

CTP Discussion

Attention for Sunday turns to a southern stream wave that
redevelops along the mid Atlantic and out to sea south of New
England Sunday evening, spreading a swath of light precip over
Pennsylvania on Sunday. The precip looks to begin as snow in
many areas before a changeover to to rain over the Lower Susq
River Valley. Start time for precip looks to range from mid-
late morning across the Laurels to early-mid afternoon for much
of the remainder of the CWA.

As the coastal low strengthens along the Mid Atlantic coast
later Sunday, it will enhance QPF over eastern zones, resulting
in a west- east QPF gradient with western zones likely remaining
under 0.25 inch liq eqvlnt, and totals increasing to about 0.50
inch over our eastern zones. Model consensus paints a stripe of
1 to 3 inches of snow along an axis from Somerset County NE
through Centre and up through Lycoming and Sullivan Counties.
Some areas will likely see higher amounts (2-5 inches). Right
now it looks like the sweet spot for these higher totals will be
over Eastern Lycoming and Sullivan Counties, where higher QPF
intersects colder air and a longer duration of snow. At this
time, little to no snow accum is expected south of I-81. Uncertainty
still remains in how far north the rain- snow line will move
during the evening hours on Sunday, accounting for at least a
couple inches of uncertainty in the snow totals across central
and northern zones.

[JDClapper]

CTP update

.SHORT TERM /SUNDAY THROUGH MONDAY/...

Focus is mainly on the Sun-night period with this package. A

positively-tilted trough over the central states will dig a

little and develop a sfc low over the Gulf Coast and lower MS

Valley. This storm will have two lows, not so much an occlusion,

but two low centers riding poleward on Sunday. The western low

takes a track to the west of the Apps, and the second to the

east. The eastern/coastal low looks like it will end up

dominating, esp by the time it gets to the DelMarVA. Thus, there

could be a decent amount of cold air at first, but the daylight

will bump the temps slightly before the sky darkens and precip

works in from the S and aloft. The precip will probably start as

a mix along the srn and wrn CWA borders, but evap cooling and

nightfall will cause it to be mainly snow for the central and

northern mountains. The temps aloft dance along the 0C isotherm

for the lowest 6-8kft along and S of US 22, eventually turning

to rain there. Some threat of ZR is there, but only a small chc,

hardly worth mentioning, and mainly over the Laurels. Slightly

farther north up to about the I-80 corridor, the temp profiles

are colder by just a couple degs C. The cloud tops there will be

helpful to make dendrites, but most of the cloud depth will be

less than ideal to keep it fluffy. SLRs could be much less than

10:1, more like 5:1 around FIG-UNV-SEG. Expect 1-2" there, with

valleys getting less than the hill tops. Slightly better

SLRs/cooler clouds just N of that line will help the snow be a

little puffy, but still wet/heavy. The marginal temps will keep

the heaviest amounts to between 2-4 inches for much of the I-80

corridor into the NE mtns despite QPF approaching 0.50" there.

Temps may rise a couple degrees by sunrise Monday and only serve

to further make it into a mushy mess. At the tail end, much of

the area could be rain, except the NW third/Alleghenies.

 

[MaineJay]

Can't tell the kids they might get a 4 day weekend yet. 

[MaineJay]

I think they hired James Michener to write the disco this morning. (Kids will love this joke)

GYX

Quote

LONG TERM /SUNDAY NIGHT THROUGH FRIDAY/...
...Another Significant Winter Storm Possible Early Next Week
Amid a Parade of Weather Systems...

The active weather pattern will continue to bring opportunities
for snow and some rain through the upcoming work week.
Temperatures will remain near to above average through most of
the period, continuing a trend present through much of the
season thus far... however a brief reprieve from a strong
Pacific Jet means a somewhat less amplified pattern translating
to weaker southerly warm/moist feed... ultimately resulting in
snowier outcomes than we have been experiencing this season, at
least through the first half of the week. While this forecast
will focus on the early-week system, attention should also be
paid to a clipper coming on its heels around Tuesday... and
another more organized system around Wednesday night into
Thursday... before finishing the week on a cooler note.

By sundown Sunday evening, an upper level trough will be
cutting toward the Eastern Seaboard as a surface low takes shape
over the Carolinas. The positive-tilt of the trough aligns
roughly with the coastline... and a downstream jet streak
provides lift in its right-entrance region, deepening low
pressure and tracking its center up along the coast Sunday night
and Monday. Snow and some southern/coastal rain break out
across New England Sunday evening, becoming most intense Monday
morning... especially south of the mountains where classic
dynamic ingredients will be in play closer to the circulation.
A Winter Storm Watch has been issued from the Monadnock region
up through the Upper Merrimack/Saco basins and across the
interior of southern Maine for potentially significant
accumulating snowfall as a result. Given the positive tilt of
the driving trough... I`m expecting this to be a fairly
progressive system passage with a limited time frame of higher
snowfall rates, although significant accums will still be
possible in that restricted window with consensus QPF generally
maxing out around 0.75-1.0", translating to around 6-10" of
snowfall potential in all-snow solutions.

The keys to this forecast, especially the rain/snow line, will be
pinning down the track of the low- and mid-level circulations amid
only a marginally-supportive air mass for snow. Ensemble consensus
brings the surface low SW to NE across Cape Cod or just beyond it
before deepening over the Gulf of Maine; tracks closer to the coast
introduce warmer air through the low levels... although it would be
an outlier solution to come close enough to the coast to
jeopardize snow accumulation over the interior, especially when
considering the 21.00Z solutions flowing in this morning
trending southward. Thus fairly strong confidence exists for
interior zones to remain all-snow, except in the warm Merrimack
Valley and toward the Mass border as a whole. Even slightly more
southern tracks bring snow to the Maine coast with more
favorable northerly drainage flow reinforcing sub-freezing
conditions in the low-levels.

Latest ensemble solutions also favor a near- or just-south-of-
the coast track for the mid-level circulation... leaving the
coast-ward half of the forecast area in a favorable region for
classic deformation/FGEN forcing... most pronounced over
central/southern Maine, where the amplifying low over the Gulf
of Maine will increase forcing overhead. Regardless of the
circulation`s track... UVVs are likely to be concentrated in the
mid-levels with a fair amount of DGZ overlap before snow falls
through a deep isothermal layer...likely to be right around
freezing closer to the parent circulation. Latest ENS/GEFS
solutions show about a 50-70% chance of keeping this layer below
freezing at the coast; while I don`t think this is enough to
include the Midcoast in the watch just yet, this would be the
area to look at for trends favoring a more southern low track,
which may allow strongest forcing to tap into cooler air and
produce strong snowfall rates on Monday.

Low pressure quickly pulls away through Nova Scotia or
thereabouts on Monday with dry slotting and a loss of forcing
leading to a quick draw-down of precipitation rates. Early
indications are that gusty, borderline strong, winds may mix
down fairly well on Monday as the system departs, with continued
snow shower activity especially across the mountains. Gusty
winds combined with wet and sticky snowfall near the rain-snow
line may lead to some power outages, though our trees are
somewhat resilient WRT northwesterly winds.

 

[PA road DAWG]

NAM coming in a bit more amped.  Clear trend overnight to drive this further NW.  less press from up top allows EC heights to rise.   Hmmmm

Edited January 21, 2023 by PA road DAWG

[HVSNOWSTORM]

Long range HRRR

[JDClapper]

Ebs and flows.

[HVSNOWSTORM]

6z hi res Canadian

[MaineJay]

18 minutes ago, JDClapper said:

Ebs and flows.

[MaineJay]

Pretty good NAM run for my backyard, would get me pretty close to average snowfall for the date.

 I'm totally rooting for the month to be +10° for average temps, but +10" on snow. It's a distinct possibility.

[JDClapper]

7 minutes ago, MaineJay said:

Pretty good NAM run for my backyard, would get me pretty close to average snowfall for the date.

 I'm totally rooting for the month to be +10° for average temps, but +10" on snow. It's a distinct possibility.

Back this way, as we have known for days, riding the line of do we mix/changeover or not, or a little, or a lot, or maybe a teensy bit or mega lots.

 

NAM is warm fmby, RGEM and ICON keep the line south of here by like 20 miles or so. No way to know for certain until tomorrow night.

[MaineJay]

4 minutes ago, JDClapper said:

Back this way, as we have known for days, riding the line of do we mix/changeover or not, or a little, or a lot, or maybe a teensy bit or mega lots.

 

NAM is warm fmby, RGEM and ICON keep the line south of here by like 20 miles or so. No way to know for certain until tomorrow night.

I'm very lucky to have the coastal front, which behaves in a fairly predictable manner. Track certainly matters, but it's often dictated by said front.

   We just can't get a decent cold air mass in place to ram some moisture into.  Hopefully a building snowpack can provide some second half of the season help 

 6z GFS was a cyclone making machine, so seems active at the very least.

[PA road DAWG]

Flirting on the edge of glory here.  Very close 

[PA road DAWG]

Gefs not impressed 

[MaineJay]

Zoom zoom. Ukie is so fast/progressive, brings hardly anything up this way.

Unlike the NAM, which brings plenty of QPF.  Fun stuff.