December 2021 Obs/Disco...Dreaming of a White-Weenie Xmas

[TauntonBlizzard2013]

29 minutes ago, CoastalWx said:

Looks like a little CJ maybe after? Cold N winds near the shore. Then we get a little more with next system.

Does this turning into a coastal a bit on some models help lock on a colder solution for this area?

[Ginx snewx]

25 minutes ago, Typhoon Tip said:

the more I look at this.. .it's sort of a weird rare scenario, of having a decent nascent polar air mass, with a mid let wind field running astride/N of the boundary; in fact..it's hard to single out main velocity tube there...it's like throwing vorticity shrapnel along the polar side. 

Anyway, the lengthens the time of maximization of QPF mechanics.   ...uh, snows and or mixes and or rains for a long time - longer than the total velocity of the ambient atmosphere would suggest.  ha.  I mean, typically, we don't see it snow for 15 hours with things moving this fast.

You know what this reminds me of?   Not sure if you were around in 1994... but we started getting into these longish duration events that were also moving fast ( once Xmas was safely behind and ruined... heh).  That circumstance was an oddball super synoptic set up where the NAO was so hugely positive it more in essence ...backed SW, and compressed the flow...  Then disturbances ran up into the fast field and stretched out and by virtue of extension ...events lasted long.  

In a way, this is a strong +AO ...but it too is biased S and is compressing matters. 

Leon 

[Ginx snewx]

4 minutes ago, TauntonBlizzard2013 said:

Does this turning into a coastal a bit on some models help lock on a colder solution for this area?

Most likely with ageo vector from the land not the sea. North of the taint line is where you want to be on WAA but mix in some CCB and it's a win.  But I should let our own Icon answer.

[powderfreak]

Pretty potent clipper moving into NNE... should be good for some low vis squalls.

[40/70 Benchmark]

GFS has that high hanging tough....not even retreating. Character of this event has really changed....PER GFS.

[Ginx snewx]

2 hours ago, 40/70 Benchmark said:

I knew you'd say that.

We'll agree to disagree that the MJO has zero contribution to the N Hem pattern anymore.

 

[Ginx snewx]

1 minute ago, powderfreak said:

Pretty potent clipper moving into NNE... should be good for some low vis squalls.

Yea that's the sweet little SW we have been watching. At one time modeling had that further south into all of NE

[Ginx snewx]

3 minutes ago, 40/70 Benchmark said:

GFS has that high hanging tough....not even retreating. Character of this event has really changed....PER GFS.

Even the Euro has the Zeus banana. Deep snow pack in Eastern Canada is always great to build those high pressures.

[40/70 Benchmark]

5 minutes ago, Ginx snewx said:

Even the Euro has the Zeus banana. Deep snow pack in Eastern Canada is always great to build those high pressures.

I'm making my visuals right now....I think its all about how quickly that energy transfers to the coast, which will be determine by how deep the parent system and how pervasive the polar airmass is. We want weaker parent energy and strong, stubborn antecedent polar air mass to induce a faster transfer to truncate the SW flow aloft....THAT is what will change this from a SWFE to a miller B. Could get best of both worlds, too, in the you get a SWFE, that then gives way to a miller B, especially north and east. 12z OP GFS shows this. You can toss the rules regarding how much snow you can get in a SWFE at that point because its no longer a SWFE..its a coastal.

[Typhoon Tip]

8 minutes ago, 40/70 Benchmark said:

GFS has that high hanging tough....not even retreating. Character of this event has really changed....PER GFS.

Couple aspect to the GFS that are bucking long trend .. makes it sort of

1) ..that high as you noted; typically, those accelerate relative to model run, with a trend to move them off faster. This?  Opposite.  Okay -

2) ..overall systemic potency ( more so since 2010 in all guidance for some reason - I think they got the modeling equiv of COVID) tends to normalize as mid range gets near.   Big events end up middling... middling, something smaller..etc.  

This is three runs in a row where the high is stalled or even back-massed, and that potency is going the other direction. 

[40/70 Benchmark]

I think a lot of guidance being diffuse and OTS is a tacit nod to the GFS scenario because it can be inferred that the parent mechanics will not be that strong...ie ultimately it will transfer sooner...kind of like when the inverse scenario of when the inverted trough shows up on models as just a provisional solution until the model realizes not much will happen.

[40/70 Benchmark]

I wouldn't forecast this right now, but I bet a lot of those seaward solutions end up as Miller B deals like the current GFS.

[40/70 Benchmark]

3 minutes ago, Typhoon Tip said:

Couple aspect to the GFS that are bucking long trend .. makes it sort of

1) ..that high as you noted; typically, those accelerate relative to model run, with a trend to move them off faster. This?  Opposite.  Okay -

2) ..overall systemic potency ( more so since 2010 in all guidance for some reason - I think they got the modeling equiv of COVID) tends to normalize as mid range gets near.   Big events end up middling... middling, something smaller..etc.  

This is three runs in a row where the high is stalled or even back-massed, and that potency is going the other direction. 

Yea, I certainly do not buy 1' in Boston....that ageo look is overdone...zero doubt.

[ORH_wxman]

7 minutes ago, 40/70 Benchmark said:

Yea, I certainly do not buy 1' in Boston....that ageo look is overdone...zero doubt.

I’m giving this another 24-36 hours to see how much north it jumps. Once inside of 72 hours we should narrow the goalposts quite a bit but this is typically the time range when we see some of these things start to trend pretty hard. We didn’t see it much at 12z today. 

[40/70 Benchmark]

3 minutes ago, ORH_wxman said:

I’m giving this another 24-36 hours to see how much north it jumps. Once inside of 72 hours we should narrow the goalposts quite a bit but this is typically the time range when we see some of these things start to trend pretty hard. We didn’t see it much at 12z today. 

I think the most prudent forecast at this juncture is a blended ensemble approach....the lighter GPS/EPS with the more robust GEFS to yield an appreciable moderate event. I have my finger on the trigger for Miller B east, though.

[ORH_wxman]

EPS is really hammering the EPIC-looking negative PNA mid-month. It just torches the central and eastern US because that PNA trough out west goes so deep into southern latitudes. 

[George001]

I’m not super optimistic about this event. I hope I’m wrong but looking at the pattern it seems like there is very little room for error.

[forkyfork]

lol

[powderfreak]

59 minutes ago, Ginx snewx said:

Yea that's the sweet little SW we have been watching. At one time modeling had that further south into all of NE

METAR KBTV 041950Z AUTO 21010KT 1/4SM +SN FZFG BKN016 BKN030 OVC065 M01/M03 A2993

[weathafella]

1 hour ago, powderfreak said:

Pretty potent clipper moving into NNE... should be good for some low vis squalls.

My daughter just texted me a picture to make me jealous 

[weathafella]

31 minutes ago, ORH_wxman said:

EPS is really hammering the EPIC-looking negative PNA mid-month. It just torches the central and eastern US because that PNA trough out west goes so deep into southern latitudes. 

Not saying this is the case but isn’t digging and holding troffing west a known euro bias?  Also, eps is most extreme.  GEPS is a good compromise between eps and GEFS.

[George001]

2 minutes ago, forkyfork said:

lol

Yeah that’s not a good pattern, unfortunately that does make sense with the polar vortex deepening. I’d like to see signs of it weakening before January.

[weathafella]

2 minutes ago, George001 said:

Yeah that’s not a good pattern, unfortunately that does make sense with the polar vortex deepening. I’d like to see signs of it weakening before January.

It’s got nothing to do with the vortex.   Do some reading.  Also, most of the time we talk about pv at H5 but are you referring to stratosphere?

[HoarfrostHubb]

BOX is a bit more bullish than I would expect this far out"

Wednesday...

It appears increasingly likely that interior southern New
England could see its first widespread accumulating snow of the
season. Ensemble model guidance (GFS, EC and GEM) probability of
24 hour 3+ inches of snowfall is now up to at least 40-50% for
Wednesday into Wednesday night across interior MA and CT. Given
how progressive the system is, initial thinking is 3-6 inches of
snow across interior MA and CT, and perhaps an inch or two
along the Boston- Providence corridor. Areas along the coast
probably see mostly if not all rain.

That said, there remains considerable uncertainty on the
placement of the rain/snow line and timing of the heaviest
precipitation as the deterministic guidance differs amongst each
other and with the ensemble guidance. The GFS deterministic run
takes the center of low pressure well inside the 70W/40N
benchmark while the EC is considerably colder. With 925mb temps
starting out at -4 to -6C Wednesday morning, it should be cold
enough to start out as all or mostly snow except for the
immediate coast Wednesday morning. Then the question becomes
whether the cold air has any staying power as the main
precipitation shield moves in. The EC and GEM deterministic
guidance are colder than the GFS. But again, would put more
weight on the ensemble guidance than deterministic guidance. And
the former actually shows more consistency as discussed above.
Still plenty of time to fine tune the specifics.

[MJO812]

38 minutes ago, forkyfork said:

lol

Good let's get it out of the way 

[moneypitmike]

2 hours ago, ORH_wxman said:

Euro is still a nice little snow event but surprised it wasn’t more beefed up. I still think it’s going to come north at some point. Hard to remember sometimes this is over 100 hours out still. 

And yet there's a thread.

[Snowcrazed71]

1 hour ago, weathafella said:

It’s got nothing to do with the vortex.   Do some reading.  Also, most of the time we talk about pv at H5 but are you referring to stratosphere?

And hence the difference between young and inexperienced, and older and wiser LOL. I will venture to Guess that George001 is a younger fellow.

[Iceresistance]

35 minutes ago, Snowcrazed71 said:

And hence the difference between young and inexperienced, and older and wiser LOL. I will venture to Guess that George001 is a younger fellow.

I'm younger too, but I'm self taught

[weathafella]

18z gfs is an eastern SNE burial.

[Damage In Tolland]

2 minutes ago, weathafella said:

18z gfs is an eastern SNE burial.

The s squashed meat grinder trend continues . This is a huge worry