December 10-12, 2023 | NE / Mid-Atlantic Winter Storm

[HVSNOWSTORM]

Deamped has happend with most storms as we get close this year. 6z NAM was significantly east and would ruin all the big snow forecasts for NYS/ WNY and shift it way SE to a narrower strip with light snows west. The GFS is close but not quite there. 

 

The Spire model which is new I guess and some advanced model they so claim, is also colder further south and east and from what I've seen has been a pretty solid model. Doesn't jump on the false snow train, again from what I've seen. It only has US view on WB. The enhanced version cost extra $$.

 

[so_whats_happening]

Flood watches hoisted across my area for 1-2" of rain, temp spikes to about 62 per forecasts tomorrow. Some snow showers were added in for sunday night into monday morning. If winter weather advisories are still a thing I would expect one from about the Lehigh valley just about Williamsport area on north to about Albany and then maybe some warning level snow just north of there into VT.

Delicate balance to just how quick the cold comes in to how much moisture is left.

[Snowadelphia]

Windshield wiper effect….

[so_whats_happening]

6 minutes ago, HVSNOWSTORM said:

Deamped has happend with most storms as we get close this year. 6z NAM was significantly east and would ruin all the big snow forecasts for NYS/ WNY and shift it way SE to a narrower strip with light snows west. The GFS is close but not quite there. 

 

The Spire model which is new I guess and some advanced model they so claim, is also colder further south and east and from what I've seen has been a pretty solid model. Doesn't jump on the false snow train, again from what I've seen. It only has US view on WB. The enhanced version cost extra $$.

 

Huh can't say I have heard of the Spire model

[HVSNOWSTORM]

[TheRex]

We currently have a Flood Watch and Winter Storm Watch issued for the upcoming weather system.  BTV's forecast discussion says the models have trended cooler for our area and snow ratios should be above 10:1 later in the storm.  They did up totals in my area to 6"-8".  It is weird that the highs the next two days will reach 50 then we will get hit with the biggest storm thus far this season.

BTV's latest forecast discussion:

Quote

.SHORT TERM /SUNDAY NIGHT THROUGH MONDAY/...
As of 424 AM EST Saturday...A strong storm system approaches the
Northeast US on Sunday. Initially, the H5 trough is positively
tilted with a weak low pressure developing near the St Lawrence
valley. Temperatures on Sunday afternoon will be unseasonably mild
in the mid 40s to low 50s, with mid 50s possible across southern
portions of the CWA. Southerly winds will also make for a breezy, if
not blustery day with wind-driven rain. Expect 0.25 to 0.75 inch of
rain to fall by early Sunday evening. With dew points surging into
the 40s, there will be rather significant snowmelt leading to the
loss of snowpack. The combination of rainfall and snowmelt runoff
will eventually lead to area river rises by Sunday night into
Monday. More details in the hydrology discussion.

Model guidance has come into better consensus that a coastal low
would develop over the Mid Atlantic and track over central/eastern
MA overnight Sunday into Monday morning, before deepening as it
lifts northeastwards into Maine. Individual members of the 00z GFS
and ECMWF continue to show remarkable consistency and clustering as
we now move into 48 hours of the onset time. While the overall upper
level flow is still fairly progressive with a neutral to slightly
positive NAO regime, models are indicating that the H5 trough does
go negatively tilted for a time, greatly increasing the odds of
colder air arriving in time for a 6 to 12 hour window of heavy, wet
snow. While the threat for pre-frontal strong to damaging winds has
diminished, concern is increasing for 35 to 40 mph post-front
northwest winds leading to power outage concerns due to snow
loading. Expect the sub-freezing 925mb isotherm to approach
Champlain valley by the pre-dawn hours on Monday before sweeping
across our entire CWA by early Monday afternoon. Expect surface
temperatures to fall into the 32-34 range for points along and west
of the Adirondacks through the pre-dawn hours, and then for areas
east of the immediate Champlain Valley by the morning commute.

Temperatures are expected to remain constant or fall slightly during
the day as strong cold air advection continues, with 925mb
temperatures falling to -6 to -8C range regionwide by sundown. The
main change with this forecast package is the expansion of the
Winter Storm Watches to northern St Lawrence county as well as
northern Champlain Valley, including Burlington. With a coastal low
tracking over east MA, this favors accumulating snow across the
Champlain valley. The 00z NAM 3km and 12km both show the potential
for heavy rain to flip over to heavy snow during the pre-dawn into
the early morning hours. Strong dynamical cooling should limit the
mixed precipitation phase. 1 inch per hour snowfall rates during the
Monday morning hours will lead to a hazardous morning commute across
the densely populated northern Champlain valley. Southern St
Lawrence county looks to be just a little too far to the west of the
northwest quadrant of the best deformation associated with the
deepening coastal low. With higher confidence in the coastal low
being the dominant surface feature, flooding threat across northern
NY has also decreased although Flood Watches remain in effect for
now. Our southeastern zones including Windsor county should see
mostly rain, thereby increasing the risk for localized urban poor
drainage flooding. This is also the area where WPC has highlighted a
slight risk in their Day 3 excessive rainfall outlook.

By Monday late afternoon into evening, as the low pressure center
lifts further north and east into northern Maine and maritime
Canada, stratiform precipitation will quickly come to an end across
northern NY and then VT, transitioning into upslope snow showers.
But as mentioned earlier, with heavy wet snow clinging onto the
trees and continued northwest gusts in the 25 to 35 mph range,
expect lingering power outages and difficult recovery efforts by
utility crew. A silver lining is that the model guidance has trended
colder, so SLRs should increase to above 10:1 for most locations
across VT by the afternoon hours, which might mitigate the snow
loading adverse impacts.

 

[TheRex]

BTV's latest snowfall map from this morning:

Quote

 

[HVSNOWSTORM]

12 minutes ago, so_whats_happening said:

Huh can't say I have heard of the Spire model

Wow NAM!

 

[so_whats_happening]

9 minutes ago, HVSNOWSTORM said:

Wow NAM!

 

The system overall seems slower, less energy running out ahead. I could dig this trend for winter time. I wish we got a broader picture with the NAM. Would love to see how it looks over the Greenland and into Canada/Alaska.

Edited December 9, 2023 by so_whats_happening

[so_whats_happening]

There is at least some upper level enhancement potential depending on where the jet sets up. NAM has a dual jet situation which helps to cool the atmosphere rather rapidly leading to a snowier situation. GFS/EURO/NAM at 250mb. It will be interesting to see if 12z runs follow suit. They are all fairly close but minor differences like that will play a role.

[Pghsnow]

Here are some short term models

[HVSNOWSTORM]

1 hour ago, so_whats_happening said:

Huh can't say I have heard of the Spire model

https://insights.spire.com/weatherbell

&

 

 

[MDBlueridge]

Some wild runs. 3K completely different run to run. If below the PA turnpike, find a hill and get on it. Preferably above 1500'. 

[so_whats_happening]

41 minutes ago, MDBlueridge said:

Some wild runs. 3K completely different run to run. If below the PA turnpike, find a hill and get on it. Preferably above 1500'. 

Lol yea unfortunately the highest around me is about 600' Just NW to harrisburg is closer to 1000' in spots.

Close but no cigar this round next frame dries mid levels out quite a bit so model probably over producing the rain look a bit. Gonna be a close one.

[TheRex]

The trend has been my friend.  Forecast started out a few days ago as rain with rain mixed with snow on Monday morning and now we are to a full blown snow storm where my snowblower will be seeing some action.

Quote

 

[Pghsnow]

[MDBlueridge]

8 minutes ago, Pghsnow said:

Using ukmet for precip output/temps is a eisky game at best. Could it be right? Absolutely 

[JDClapper]

Recently updated probabilities for 1, 2, and 4+", through 1pm Monday.

 

[telejunkie]

31 minutes ago, TheRex said:

The trend has been my friend.  Forecast started out a few days ago as rain with rain mixed with snow on Monday morning and now we are to a full blown snow storm where my snowblower will be seeing some action.

 

Still only a Flood Watch down this way, but after 12z runs, thinking BTV may hoist one in their afternoon update. Already told my kids it'll probably be a 3 day weekend....

[Pghsnow]

Lock it in...

[TheRex]

51 minutes ago, telejunkie said:

Still only a Flood Watch down this way, but after 12z runs, thinking BTV may hoist one in their afternoon update. Already told my kids it'll probably be a 3 day weekend....

I'd be surprised if they don't make that change in their next update.

My youngest son has his driving test scheduled for Monday at 11 am.  My wife thinks it will still happen because this is VT and snow happens.  However, I think there aren't many people willing to get into a car with a new driver and see if the rookie driver can handle what Mother Nature can dish out.

[Pghsnow]

[bigben89]

1 hour ago, JDClapper said:

Recently updated probabilities for 1, 2, and 4+", through 1pm Monday.

 

So you’re saying there’s a chance lol

 

[JDClapper]

Just now, bigben89 said:

So you’re saying there’s a chance lol

 

lol always a chance!  haha  Heck, this past Thursday AM, we had a very low chance of 1".. got 1.25" and places 15-25 miles west raked in 3, 4".  Probabilities are fun.  Could have just as easily received 0 flakes too.  /shrugs

[MDBlueridge]

8 minutes ago, Pghsnow said:

Man the euro has been consistent.