The Return of the 12/5 Snowstorm

[SnowenOutThere]

So, over the past couple days I've been quite the downer on this storm having a possibility of bringing widespread snow to the area. In the past I mainly felt this way as we were relying on a convoluted mess of shortwave interactions. However, in the past 12 hours modeling has moved to put us on a far easier path to victory as they reemphasize shortwave 1 (previously we were using shortwave 3 even days ago) as the dominant way to get precipitation into our area. Of course, it could shift the other way but this is exactly the trend we want to see. Lets take a look at the difference between the past GFS runs that leave us high and dry and the Euro/NAM camp that actually has a real storm. 

This GFS run shows our first shortwave that gets compressed by a combination of factors. We have energy flooding the west (feature 3) and another NS shortwave which really is the main issue (feature 4 note the string of vorticity connecting to feature 3). Feature 2 is just sorta helping with moisture transport and imo isn't overly important. So, we run this forward in time and we see this:

Feature 1 is now basically nonexistent as it is a ribbon of vorticity from Texas to Virginia. So, the real push northward of precip is instead by feature 2 and 3/4 interacting with each other which frankly was never going to workout unless we got a minor miracle (and the thermals would be bad from the extended return flow anyways and was shown by the GFS having rain where there was any precip). It was from this perspective that I believed there was no way we could get a storm into the Mid-Atl

Lets compare to the Euro/NAM:

We already have shortwave 1 way more clearly defined and less strung out. This is what actually causes a storm in this run not shortwave whatever the hell the GFS does! Notice how much simpler this is! its just a shortwave out west moving east into cold air! We can legitimately do that! Of course, features 3 and 4 are still there but they are held back and give us a little more breathing room. 

 

By Friday morning itself the difference is even more clear as there is still a consolidated mass of vorticity and that creates our storm. What we need to look for is for features 3/4 to slow down or dig south at a sharper axis to encourage the first shortwave to consolidate. For instance see the difference between 6z having the energy out northwest of our storm being flat across Chicago and the 12z having it spike north south west of Chicago area and encourage development downstream instead of suppressing it. 

I think that piece of energy is the main thing we have to watch (the Nam 3k has an amazing depiction of how a flatter and faster NS energy will suppress the flow but sadly I don't have the upload space but please go and make one yourself), if it manages to hold back or dig further south while maintaining a good axis I think we're in the game to get a nice snow day Friday. 

 

TDLR: I am no longer Debbie downing Friday. We got a legit shot if the Euro/Nam is right in the handling of shortwave 1 as the primary piece of energy.

 

[Eskimo Joe]

Bring us home @SnowenOutThere. A cold powder event would be amazing, even if it's a 1" - 2" event.

[bncho]

12z EPS is a substantially larger signal than 6z.

[adelphi_sky]

2 minutes ago, Eskimo Joe said:

Bring us home @SnowenOutThere. A cold powder event would be amazing, even if it's a 1" - 2" event.

A weekend snow would be nice so that we can enjoy it without having to work. Hoping it starts after rush hour.

[SnowenOutThere]

45 minutes ago, SnowenOutThere said:

(the Nam 3k has an amazing depiction of how a flatter and faster NS energy will suppress the flow but sadly I don't have the upload space but please go and make one yourself)

Don't know if this will actually embed how I want it to but this is what I mean. You can really see the string of vorticity in the early-middle part of the loop that suppresses the flow to the east (hopefully we get that to trend less intense/further north). Then we can see the second part with the west getting flooded with unconsolidated energy which results in the shortwave collapsing between the flow to the south and the western push. 

https://imgur.com/a/Eloa7k7

[EastCoast NPZ]

I'm pretty pessimistic after today's debacle.

[wxmeddler]

All hail the Dec. 5th magic!

[mitchnick]

Srefs at the end of their recent run. This is just 24hr precip. You can check out other stuff at this Pivotal link.

https://www.pivotalweather.com/model.php?m=srefens&p=qpf_024h-mean-imp&rh=2025120215&fh=87&r=conus&dpdt=&mc=&pwplus=1

[ravensrule]

24 minutes ago, EastCoast NPZ said:

I'm pretty pessimistic after today's debacle.

Shocking, you are NEVER pessimistic. 

[mitchnick]

Accuwx take

 

[bncho]

Anybody wanna PBP the NAM?

[mitchnick]

Just now, bncho said:

Anybody wanna PBP the NAM?

Do you want to get banned?

[87storms]

This is the one, unless it’s the next one. Gonna need to rely on a Jan 30, 2010 situation. That system is way too far south rn.

[wxdude64]

40 minutes ago, ravensrule said:

Shocking, you are NEVER pessimistic. 

That happens when you live with the Saguaros.

[Maestrobjwa]

Only reason I'm not as enthused is that these sliders don't seem reach Baltimore north lately and I have no idea why. Something cuts of the moisture and I'd love to know what it is...so until one finally works here I find it hard to believe.

[mitchnick]

Nam looks flatter

Edit: flattened

[mitchnick]

Maybe some trailing energy....maybe?

[stormtracker]

She gone on the NAM

[SnowenOutThere]

2 minutes ago, mitchnick said:

Nam looks flatter

Edit: flattened

It has an extra lobe of energy further east than the 12z run and generally has the NS flatter instead of spikier worse run but impossible to know if itll verify yet

18z

12z

[mitchnick]

5 minutes ago, stormtracker said:

She gone on the NAM

Yeah, but it almost looks like there's something behind the Friday system.

Nam map is just a mall parking lot during Christmas Eve.

[SnowenOutThere]

3 minutes ago, mitchnick said:

Maybe some trailing energy....maybe?

That would be the shortwave three option to get a storm which I mean maybe? Though no way to know if it'll be accurate this far out. 

[SnowenOutThere]

Just now, SnowenOutThere said:

That would be the shortwave three option to get a storm which I mean maybe? Though no way to know if it'll be accurate this far out. 

Doesnt matter as we lose the thermals hard. I think if we're gonna get frozen we need shortwave one to work out

[mitchnick]

Just now, SnowenOutThere said:

Doesnt matter as we lose the thermals hard. I think if we're gonna get frozen we need shortwave one to work out

I was just looking at that thinking ain't it always the case.

[stormtracker]

3 minutes ago, mitchnick said:

Yeah, but it almost looks like there's something behind the Friday system.

Nam map is just a mall parking lot during Christmas Eve.

Yeah, I see it, just can't know what it's gonna do.   But like you said, it's loaded up...just gotta hope we get a spark

[bncho]

The NAM is a bad model 84 hours out. I'm definitely not saying this because it sucks.

[WEATHER53]

9 minutes ago, stormtracker said:

She gone on the NAM

CAB in effect as now 2.5 days out.

i no longer rely on models for anything nearly specific and just the very general low to our south which may be string or weak and may curl up the coast or go out to sea.  All possibilities will be shown so models  score well come verification of outcome 

This last event was a departing high off Maine and that showed early and that’s what happened .  Never good for us.  

 

[mitchnick]

2 minutes ago, bncho said:

The NAM is a bad model 84 hours out. I'm definitely not saying this because it sucks.

You're right. Rule of thumb should always be disregard anything past it's 78 hour wheelhouse.

[Solution Man]

We need the energy to drop in and lead and not trail the NS, maybe it work for once

[soadforecasterx]

 18Z icon shows hope for the 5th