Fall 2022 Medium-Long Range Discussion

[CAPE]

43 minutes ago, Chris78 said:

Looks ok after the first 5 days or so in December.

Hopefully the EPS comes around.  Seems to want to hold the colder anomalies further west.

The advertised looks on both the EPS and GEFS are acceptable at this range- the differences are probably related to the MJO wave progression, with the EPS moving it more quickly through phase 7 then dissipating it.

[cbmclean]

14 minutes ago, CAPE said:

The advertised looks on both the EPS and GEFS are acceptable at this range- the differences are probably related to the MJO wave progression, with the EPS moving it more quickly through phase 7 then dissipating it.

Someone recently made the claim that the EPS has a bias towards killing MJO waves.  Is that a known thing?

[yoda]

06z GEFS looks pretty nice IMO after Day 10... hints of a +PNA out west with some decent blocking up top

[CAPE]

Just now, cbmclean said:

Someone recently made the claim that the EPS has a bias towards killing MJO waves.  Is that a known thing?

Not sure, but most guidance is suppressing it in ph7 or just as it progresses to ph8. The general tendency in a Nina is for convection to not progress far into the western Pac, ofc that is somewhat dependent on the specific location of the SST anomalies.

[CAPE]

2 hours ago, CAPE said:

 Reposting stuff like this from the NE forum really doesn't add value to the discussion here tbh. 

To be clear, I am referring to reposting of redundant model guidance maps that have literally just been posted and discussed by folks in this thread. Seems like it should add some new insight/a unique perspective.

[North Balti Zen]

I thought ORH’s note was helpful context but maybe that’s just me…

[CAPE]

11 minutes ago, North Balti Zen said:

I thought ORH’s note was helpful context but maybe that’s just me…

That's not the only repost from the NE forum over the past few days, just to give a broader context. And I am glad you found it helpful!

[clskinsfan]

18Z GFS has a chance for some frozen on the 8th for those of us to west. Looks like a vort riding up a front kinda deal. Way out there. But something to watch. I still do like the look of that mid December time period for sure. 

[CAPE]

12 minutes ago, clskinsfan said:

18Z GFS has a chance for some frozen on the 8th for those of us to west. Looks like a vort riding up a front kinda deal. Way out there. But something to watch. I still do like the look of that mid December time period for sure. 

Agree that period has looked interesting on the ens runs, with colder air bleeding south behind a wave around the 4-5th. GEFS has been hinting at additional pieces of energy riding along the boundary in the days that follow, with colder air in place.

[Maestrobjwa]

Laughing at "wee", lol

[CAPE]

11 minutes ago, Maestrobjwa said:

Laughing at "wee", lol

The -NAO on the EPS has looked more impressive and with better placement(further south across GL) than the GEFS on recent runs. Lets hope the Europeans are more correct here. We are likely going to need a stout block to overcome early-mid Dec climo and ofc Nina tendencies.

[CAPE]

This is a really nice look up top, and might be the period where something of interest could transpire.

[Bob Chill]

A Dec AO or NAO in the -1.3 or lower range  indicates both a -ao/nao in Jan 75-80% of the time and about 60% in Feb. One of the best long term winter pattern predictors I've found. Works in reverse quite well too. Do I need to post those stats or do the memories of the multi-year soul killing blue ball in the arctic cover that? Lol

An important piece for increased winter wx odds seems to be lining up and holding in time now. If it sets up stable, this general type high latitude blocking pattern lasts on avg 30-45 days. Doesn't mean deep winter as our area always requires more than one feature lining up but the possibility of our biggest thorn not drawing blood keeps looking better

I posted a bunch of data on this stuff back in 2012 or so. Might be a good time for me to dig it up. Yep, it's been that long since we've had a run of classic blocky winters. 

 

ETA: AO is the bus driver as the domain space is far larger than the NAO and affects wx flow differently. An anomalous -NAO is often an extension of a deep -AO. Either way, a deep blocking episode in Dec that makes the east cold rarely indicates a warm boring winter going forward.

[CAPE]

4 minutes ago, Bob Chill said:

A Dec AO or NAO in the -1.3 or lower range  indicates both a -ao/nao in Jan 75-80% of the time and about 60% in Feb. One of the best long term winter pattern predictors I've found. Works in reverse quite well too. Do I need to post those stats or do the memories of the multi-year soul killing blue ball in the arctic cover that? Lol

An important piece for increased winter wx odds seems to be lining up and holding in time now. If it sets up stable, this general type high latitude blocking pattern lasts on avg 30-45 days. Doesn't mean deep winter as our area always requires more than one feature lining up but the possibility of our biggest thorn not drawing blood keeps looking better

I posted a bunch of data on this stuff back in 2012 or so. Might be a good time for me to dig it up. Yep, it's been that long since we've had a run of classic blocky winters. 

WDI?

[Bob Chill]

2 hours ago, CAPE said:

WDI?

Whomever cracks the kinda sorta decadal cycle of the AO will become a legend. It's there somehow/somewhere. I tried to find any kind of predictor other than approx 10 years with twists and turns. Lol. You can see the groups in the 60s/70s/80s easy. Things got a little weird in the 90s thru current but it's still there and this year would be "on time" for the switch. But it's always a rear view thing. 

[CAPE]

A persistent -AO is probably the number one index for increased chances of a fun winter in the MA.

I usually post this once every winter because it is such a great CWG article by Wes detailing the most important indices and combos for cold/snow in the DC area. Every MA snow weenie should read this at least once.

https://www.washingtonpost.com/news/capital-weather-gang/wp/2015/11/12/what-the-different-weather-patterns-might-mean-for-snow-this-winter/

 

[Bob Chill]

  I must be really awake or something. 3 legit wx posts in a row... my intuition must be kickin'... 

In a vacuum of reasons why, it's still pretty obvious we are losing on the margins and borderline setups due to warmer winter temps. It's been raining when it shouldn't. Don't want to dig any deeper than that.

The NAO can really help with marginal events just because of common mid level flow under a block. We get the cold dry feed pushing back against storms instead of running away. Still doesn't win the game exclusively because sometimes the "cold dry feed" is straight out of unusually warm New England.

Blocks aren't everyone's friend either. The further north you get the less you want to see a big red monstrosity over Greenland or Baffin. You also don't want to see nasty 50/50s spinning in place. But that's there and this is here. If we start seeing banana like highs sliding across to our north in mid Dec, it's prob only a matter of time b4 the shovels get dusted off and oiled up. 

 

ETA: @CAPE see if u can find the 2012ish article from Wes. He used my AO data. Would save me a lot of time. It's been a while + several PCs since I did the research. 

[CAPE]

Maybe this one?

https://www.washingtonpost.com/blogs/capital-weather-gang/post/history-does-not-support-a-terribly-snow-winter-in-dc/2012/11/20/06411868-333f-11e2-9cfa-

Also found this..

e41bac906cc9_blog.htmlhttp://voices.washingtonpost.com/capitalweathergang/2010/11/why_was_last_year_so_snowy_par.html

 

[CAPE]

This is the clean, uncomplicated way we get on the board as the favorable pattern is unfolding. Monster west based -NAO with a quasi-stationary vortex underneath- a bit too southwestward displaced so the wave ends up somewhat suppressed here. Overall a classic look up top though. Guidance should be spitting out more looks like this going forward.

[WxUSAF]

This is kinda nuts for a D13 ensemble mean for the -NAO. That Dec 6-11 period is an above-average early season snow threat window. 

 

[CAPE]

2 minutes ago, WxUSAF said:

This is kinda nuts for a D13 ensemble mean for the -NAO. That Dec 6-11 period is an above-average early season snow threat window. 

 

12z GEFS suggests a trackable wave around the 8th. 

[cbmclean]

16 minutes ago, WxUSAF said:

This is kinda nuts for a D13 ensemble mean for the -NAO. That Dec 6-11 period is an above-average early season snow threat window. 

 

Asking as someone trying to make a significant effort to understand: isn't that a nasty -PNA signal though?

[WxUSAF]

3 minutes ago, cbmclean said:

Asking as someone trying to make a significant effort to understand: isn't that a nasty -PNA signal though?

Yes it is, which normally is a bad sign for our snow chances. But with high latitude blocking like that, the whole conus is basically BN temp wise. 

[CAPE]

39 minutes ago, WxUSAF said:

Yes it is, which normally is a bad sign for our snow chances. But with high latitude blocking like that, the whole conus is basically BN temp wise. 

Yeah that's the way to mitigate it. -EPO, -AO, -NAO. It might work for us with waves taking the southern route and ejecting eastward, which is sometimes difficult to achieve in a Nina.

[Ralph Wiggum]

21 minutes ago, WxUSAF said:

Yes it is, which normally is a bad sign for our snow chances. But with high latitude blocking like that, the whole conus is basically BN temp wise. 

Also, as noted in my home sub, there is a neg 500 anomaly wobbling around and trying to move near the Aleutians towards the tail end of the GEFS run. Something else to watch that could prove beneficial as we move into the 2nd week Dec.

[psuhoffman]

25 minutes ago, cbmclean said:

Asking as someone trying to make a significant effort to understand: isn't that a nasty -PNA signal though?

@WxUSAF and @CAPE nailed it but I wanted to add a visual. Please don’t interpret this as an expectation. It’s not February and it’s not an El Niño. But…this is the h5 from our snowiest 15 day period ever. 

Everything is a balancing act in waves and every ripple in one place impacts the others. Without ridiculous high lat blocking that pna would be a big problem.  On the flip side that kind of blocking with a +pna might just be cold and dry. 

[Jersey Andrew]

1 minute ago, psuhoffman said:

@WxUSAF and @CAPE nailed it but I wanted to add a visual. Please don’t interpret this as an expectation. It’s not February and it’s not an El Niño. But…this is the h5 from our snowiest 15 day period ever. 

Everything is a balancing act in waves and every ripple in one place impacts the others. Without ridiculous high lat blocking that pna would be a big problem.  On the flip side that kind of blocking with a +pna might just be cold and dry. 

Was February 2010 crippling Snowpocalypse accompanied by West Coast troughing?

[CAPE]

10 minutes ago, Ralph Wiggum said:

Also, as noted in my home sub, there is a neg 500 anomaly wobbling around and trying to move near the Aleutians towards the tail end of the GEFS run. Something else to watch that could prove beneficial as we move into the 2nd week Dec.

I noticed that too. That TPV near the sea of Okhotsk has been a strong/stable feature, and as advertised has been periodically knocking down the EPO ridge. It seems to weaken and retro a bit in the LR on today's GEFS, morphing into more of an Aleutian low and allowing the -EPO to remain more intact. That feature is critical in dictating the character of the Pac ridge imo.

[CAPE]

15 minutes ago, psuhoffman said:

@WxUSAF and @CAPE nailed it but I wanted to add a visual. Please don’t interpret this as an expectation. It’s not February and it’s not an El Niño. But…this is the h5 from our snowiest 15 day period ever. 

Everything is a balancing act in waves and every ripple in one place impacts the others. Without ridiculous high lat blocking that pna would be a big problem.  On the flip side that kind of blocking with a +pna might just be cold and dry. 

You need to post more dude. Things are looking promising. We are on the doorstep of Dec and the advertised look is stellar for a change. Sure all sorts of shit can go wrong, but rather the guidance be teasing us with something favorable vs the usual shutout look lol.

[Weather Will]

WB 12Z GEFS teleconnections.  Look pretty good to me.  One thing about the PNA, though negative it is not at record low -4 standard deviation to overwhelm everything else like last December…