December 2021 Medium/Long Range Discussion Thread

[CAPE]

Just a hunch, but I don't think "too cold" is going to be high on the list of reasons we fail to snow.

[IronTy]

1 hour ago, WinterWxLuvr said:

Vodka cold rarely, rarely will produce snow here. And usually only upon its exit

There was one time like ten years ago when I went to bed expecting an inch or two of snow but it was so cold the ratios were way higher than forecasted and we got like 10".  Those were the halcyon days.  

[IronTy]

I'm also sticking with my theory that our climate is transitioning to a warm/wet season and cool/dry season type climate.  I probably just gartman'd myself and called the top.  

[North Balti Zen]

3 hours ago, CAPE said:

Just a hunch, but I don't think "too cold" is going to be high on the list of reasons we fail to snow.

I mean,  maybe? We do excellent with deep cold suppression and snow in myrtle beach…

[CAPE]

10 minutes ago, North Balti Zen said:

I mean,  maybe? We do excellent with deep cold suppression and snow in myrtle beach…

Suppression mostly happens without a "vodka" cold outbreak. That is typically a function of the pattern(too much confluence) and bad timing with NS vort lobe passes.

[WinterWxLuvr]

14 minutes ago, CAPE said:

Suppression mostly happens without a "vodka" cold outbreak. That is typically a function of the pattern(too much confluence) and bad timing with NS vort lobe passes.

What causes that confluence? Big blobs of frigid air sitting like a stone over Quebec?

[psuhoffman]

6 minutes ago, WinterWxLuvr said:

What causes that confluence? Big blobs of frigid air sitting like a stone over Quebec?

I’m with CAPE. We can get confluence without arctic air in the pattern. And we can get a storm with it. Actually with the warm waters I’d take my chances in a suppressive pattern WITH arctic air to enhance baroclinicity. The last 2 weeks of January last winter is what suppression without cold looks like.  The last several true arctic shots we got did lead to snow. 

[WinterWxLuvr]

12 minutes ago, psuhoffman said:

I’m with CAPE. We can get confluence without arctic air in the pattern. And we can get a storm with it. Actually with the warm waters I’d take my chances in a suppressive pattern WITH arctic air to enhance baroclinicity. The last 2 weeks of January last winter is what suppression without cold looks like.  The last several true arctic shots we got did lead to snow. 

I’m just saying the suppression is caused by something. I think the position of the cold matters and I don’t think we want to be frigid HERE. Clippers are the only thing I know might work in that setup, unless the cold airmass is retreating. Just my opinion. Doesn’t mean I’m right

[CAPE]

24 minutes ago, WinterWxLuvr said:

What causes that confluence? Big blobs of frigid air sitting like a stone over Quebec?

No. A west based, somewhat southward displaced -NAO with a vortex forced/trapped underneath can cause suppression. Think 2009-10 from the perspective of someone in NE. That was suppression to them, perfect for us. No super cold around.

 

[North Balti Zen]

16 minutes ago, WinterWxLuvr said:

I’m just saying the suppression is caused by something. I think the position of the cold matters and I don’t think we want to be frigid HERE. Clippers are the only thing I know might work in that setup, unless the cold airmass is retreating. Just my opinion. Doesn’t mean I’m right

This

[North Balti Zen]

Pretty generally - “vodka cold” is shit for big storms. We are not pouring snow at 3 degrees. 
 

 

[CAPE]

24 minutes ago, North Balti Zen said:

Pretty generally - “vodka cold” is shit for big storms. We are not pouring snow at 3 degrees. 
 

 

A more typical 'Arctic' airmass enhancing a baroclinic zone in a favorable pattern can produce some pretty cold/high ratio snow events. The Blizzard of 1983, a big storm, produced heavy snow with temps in the low to mid teens, as did the late Jan 2010 moderate snowstorm, just to name a couple examples.

Too much confluence resulting in a suppressed storm track is not a vodka cold thing. Sure a brutally cold airmass with a strong cold front sweeping through can push the baroclinic region wayyy off the coast and make for dry conditions. We don't get that kind of cold much though. This whole dopey convo started with someone commenting on a "vodka" cold airmass being on the doorstep of the US at day 15 of a GFS op run. So a couple things- it was a damn op run, and even if it did verify, that cold would dump well west of here. Reality is we don't usually get direct shots of brutal cold in this area, esp not in recent times. So worrying over that possibility and that it might be dry and not produce snow is a little silly, considering we have a multitude of other more likely failure modes.

I think there might be some conflation here with the tendency for us to see cold and dry following a mild rain storm. That is a function of our location/latitude, and the fact that we need a lot of elements to come together to have cold enough air in place and a storm that takes a favorable track.

[psuhoffman]

1 hour ago, WinterWxLuvr said:

I’m just saying the suppression is caused by something. I think the position of the cold matters and I don’t think we want to be frigid HERE. Clippers are the only thing I know might work in that setup, unless the cold airmass is retreating. Just my opinion. Doesn’t mean I’m right

 

51 minutes ago, North Balti Zen said:

Pretty generally - “vodka cold” is shit for big storms. We are not pouring snow at 3 degrees. 
 

 

Respectfully disagree. It snowed in 2015 the day after one of our coldest February arctic shots I can remember.  And it snows plenty in colder places at 3*. You know why it doesn’t snow often here at 3*?  Because it isn’t often that cold here!  How often is it 3* when cloudy? (No radiational cooling). Plus any strong storm will press the boundary back north so even if it WAS that cold right before it’s incredibly unlikely to stay that cold here at this latitude during a storm!  But we’ve had some nice storms during periods of arctic cold shots. 2 of the last 3 arctic shots produced significant snowstorms. 

[psuhoffman]

9 minutes ago, CAPE said:

 

I think there might be some conflation here with the tendency for us to see cold and dry following a mild rain storm. That is a function of our location/latitude, and the fact that we need a lot of elements to come together to have cold enough air in place and a storm that takes a favorable track.

THIS x100!!!  The lack of snow isn’t because it’s cold. The issue is we often only get really cold at this latitude and this close to the coast in the NW flow behind a wave. Then it warms up in the return flow ahead of the next wave. Cold dry warm wet. But the dry isn’t because it’s cold it’s just a coincidence because we only got cold behind the waves in the flow. 

[George BM]

7 minutes ago, psuhoffman said:

 

Respectfully disagree. It snowed in 2015 the day after one of our coldest February arctic shots I can remember.  And it snows plenty in colder places at 3*. You know why it doesn’t snow often here at 3*?  Because it isn’t often that cold here!  How often is it 3* when cloudy? (No radiational cooling). Plus any strong storm will press the boundary back north so even if it WAS that cold right before it’s incredibly unlikely to stay that cold here at this latitude during a storm!  But we’ve had some nice storms during periods of arctic cold shots. 2 of the last 3 arctic shots produced significant snowstorms. 

Yeap. PD1 was actually immediately preceded by a super cold airmass.

There was a morning low of -14F at IAD on 2/18/1979 with the temp only maxing out at 8F before midnight. 2.5" of snow had already fallen by then. 

[CAPE]

1 minute ago, George BM said:

PD1 was actually immediately preceded by a super cold airmass. There was a morning low of -14F at IAD on 2/18/1979 with the temp only maxing out at 8F before midnight. 2.5" of snow had already fallen by then. 

I used 1983 as an example but yes 1979 is probably better.

[psuhoffman]

5 minutes ago, George BM said:

Yeap. PD1 was actually immediately preceded by a super cold airmass.

There was a morning low of -14F at IAD on 2/18/1979 with the temp only maxing out at 8F before midnight. 2.5" of snow had already fallen by then. 

 

1 minute ago, CAPE said:

I used 1983 as an example but yes 1979 is probably better.

PD2 had arctic air around, but mostly just north of us. 1994 arctic air didn’t stop us from getting ice storm after ice storm.  And it was absolutely frigid up In central PA that year as they got buried by snow.  And it was arctic cold up there in 2014 as I got a ton of snow.  The laws of physics don’t change in DC!  It just doesn’t get that cold that often to have a chance to snow!  
 

no we don’t want some 1050 high over DC but how often does that actually happen?  I suppose it’s possible.  1977 happened.  But from range I’ll take arctic air and play the odds  

 

[CAPE]

1 minute ago, psuhoffman said:

 

PD2 had arctic air around, but mostly just north of us. 1994 arctic air didn’t stop us from getting ice storm after ice storm.  And it was absolutely frigid up In central PA that year as they got buried by snow.  And it was arctic cold up there in 2014 as I got a ton of snow.  The laws of physics don’t change in DC!  It just doesn’t get that cold that often to have a chance to snow!  
 

no we don’t want some 1050 high over DC but how often does that actually happen?  I suppose it’s possible.  1977 happened.  But from range I’ll take arctic air and play the odds  

 

You know where I am I will roll the dice with having true arctic air in place every time. The 'give me precip and I'll take my chances with cold' credo ends up mostly rain 9 times out of 10.

[psuhoffman]

2 minutes ago, CAPE said:

You know where I am I will roll the dice with having true arctic air in place every time. The 'give me precip and I'll take my chances with cold' credo ends up mostly rain 9 times out of 10.

Up here when I fail it’s more often from suppression.  Things go north of course but usually it’s obvious and not close so it’s not really a “fail”. But the suppression isn’t from cold. Like you said it’s just from the flow or bad timing. And 90% of my snow is rain where you are but even here I’ll take the cold and roll the dice. 

[CAPE]

4 minutes ago, psuhoffman said:

Up here when I fail it’s more often from suppression.  Things go north of course but usually it’s obvious and not close so it’s not really a “fail”. But the suppression isn’t from cold. Like you said it’s just from the flow or bad timing. And 90% of my snow is rain where you are but even here I’ll take the cold and roll the dice. 

I can enjoy mild rain 9 months out of the year, so if the 'risk' for the other 3 is arctic cold and dry, I will gladly take that and enjoy it. Not like an arctic airmass stays around at this latitude more than a few days anyway.

[MillvilleWx]

Generally speaking, MA climo has a propensity to have some decent snow chances following epic cold regimes due to the baroclinic zone pushed south for a time which usually precludes a wave to the south that eventually pulls back north when the harsh cold relaxes and the moisture field from the wave moves up into a primed antecedent airmass. SWFE events typically have some of the nicer snowfalls in the area, but of course they can switch over to IP/ZR thanks to the enhanced SW flow causing boundary layer warming. Our biggest snowfalls are always phased, split stream events that align perfectly, but those are so far and between, but that's why they are special.

Having a -NAO is very important for us to get those bigger storms, most of the time at least because they cause a slow down of the upstream wave pattern and allow for increased meridional components, thus opening the door for phasing or waves passing south of 37N, which to me is the magic latitude for potential in these parts. We have our sweet spots, and ours is around that 34-37N lat where as places like Philly want it a little further to the north.  

[WinterWxLuvr]

You guys are saying what I’m saying. There have been several mentions of “preceding” cold air masses. That’s what I am calling a retreating cold air mass. 
 

@CAPE you mentioned a vortex. Isn’t that just a cold dense airmass?

[psuhoffman]

7 minutes ago, WinterWxLuvr said:

You guys are saying what I’m saying. There have been several mentions of “preceding” cold air masses. That’s what I am calling a retreating cold air mass. 
 

@CAPE you mentioned a vortex. Isn’t that just a cold dense airmass?

Yea but you need the arctic cold first lol 

[Weather Will]

Enjoyed reading the analysis above,  but don’t see any cold air through Christmas on the latest ensemble runs to suppress any potential storms. Hopefully we will see some cold air in range over the next week or so on the ensembles, I will be turning the hose back on and watering on Saturday.   Seems like the news right now is we are in a drought.

[CAPE]

8 hours ago, WinterWxLuvr said:

You guys are saying what I’m saying. There have been several mentions of “preceding” cold air masses. That’s what I am calling a retreating cold air mass. 
 

@CAPE you mentioned a vortex. Isn’t that just a cold dense airmass?

Vortices are moving/rotating around all the time in the upper levels. Sure they represent areas of relatively colder/denser air, but when we have a poorly timed one to our north/ it tracks a bit too far south, the mechanism that can lead to suppression has more to do with the flow- too much confluence/convergence can slow/flatten the flow underneath, leading to weaker lift (PVA) from an approaching southern wave, and direct it off to the east before it gains enough latitude. It's often a fine line, like just about everything in this general area in order to get a good snowstorm.

[Weather Will]

WB 6Z GFS much different than overnight run….has our Christmas miracle storm….

[CAPE]

Btw, I am all for

VODKA COLD OUTBREAK!

It is so rare here, and it represents the ultimate cold airmass, I guess. Hate using JB lingo.

I'll take my chances we get snow on the front end or as it moderates/ retreats. We had some pretty darn cold airmasses in 2014 with the -EPO. They were generally fleeting, and managed to produce light to moderate snow events.

[WxUSAF]

DCA hasn’t been below 22F in like 3 years? So yeah, give me the vodka cold so it can sneak down to 21F in an intrahour!

[CAPE]

Latest runs of the GEFS build heights nicely into the NAO domain leading up to Christmas. Eastern ridge is flatter/weaker, with more of a gradient pattern look, so not impossible to see something of interest in that timeframe as advertised. EPS moves in that direction but then backs off, leaving the +height anomalies near Scandinavia at day 15. CMC ens looks more like the EPS, but has leading edge of colder air bleeding into the N plains. 

[WinterWxLuvr]

1 hour ago, Weather Will said:

WB 6Z GFS much different than overnight run….has our Christmas miracle storm….