December 2019 Med/Long Range Disco

[psuhoffman]

7 minutes ago, Bob Chill said:

Just a hunch but my guess is the euro type scenario is too quick. It sure looks like the best chance of the season is setting up near mid month though. 

None of the details will be the same but what’s exciting is seeing all the guidance move towards the same general look at H5. The idea of storm threats in that general period comes from that look. The specifics will change until we get this inside day 5/6 but keep that pattern look and we should have a chance. 

[WEATHER53]

Mechanically cold air keeps reloading in the Mongolia prime zone, traverses the poles and ends up in a good position to our north and equally important exits eastwardly. Often a really cold high will arrive, settle over us, move southeast and we warm  up considerably on backside and it may stay put as a se ridge. That’s not happening this winter season.

 

[WxUSAF]

DT’s final winter forecast is out. Clear lean toward cold and snowy. 

[Rtd208]

DT (WxRisk) final winter outlook.

https://onedrive.live.com/view.aspx?resid=1CA2F9A16D1A6375!13380&ithint=file%2cpptx&authkey=!AC_lsieTX6tAQh0

[Ji]

25 minutes ago, Bob Chill said:

All in good fun being so far out but this would be an all frozen storm for most. Especially west of 95. No way this depth of CAD gets dislodged. 

 

ETA:

Surface wind out of the N/NE all the way down to GA. Notice the little spin near Savannah GA? There's the jump. lol. 

This is a Christmas miracle but I need it to happen 1-2 days later. Hope you are right about it may be too early 

[Drop the Trough]

5 minutes ago, Rtd208 said:

DT (WxRisk) final winter outlook.

https://onedrive.live.com/view.aspx?resid=1CA2F9A16D1A6375!13380&ithint=file%2cpptx&authkey=!AC_lsieTX6tAQh0

wasn't he calling for a pattern change to warmer after December 9th just 3 days ago? He changes with the wind, brags to everyone how he is the only met who can accurately forecast 3 weeks out, but he changes his forecast every few days.

[Bob Chill]

3 minutes ago, Ji said:

This is a Christmas miracle but I need it to happen 1-2 days later. Hope you are right about it may be too early 

Don't stress man. Odds strongly favor things not working out. 

[BTRWx's Thanks Giving]

38 minutes ago, Rtd208 said:

DT (WxRisk) final winter outlook.

https://onedrive.live.com/view.aspx?resid=1CA2F9A16D1A6375!13380&ithint=file%2cpptx&authkey=!AC_lsieTX6tAQh0

What update?  All he did was change %s on a couple pages!

[WxUSAF]

Probably not surprising in the era of nondivergent ensembles, but the EPS looks reasonably close to the op euro at D10. GGEM actually looks quite similar too. 

[Bob Chill]

12 minutes ago, WxUSAF said:

Probably not surprising in the era of nondivergent ensembles, but the EPS looks reasonably close to the op euro at D10. GGEM actually looks quite similar too. 

MSLP panels look pretty good. CAD sig in place and low pressure to the SW. I'd be perfectly fine with a west track front end thump. Whatever it takes to get on the board with something other than a T

[aldie 22]

27 minutes ago, Bob Chill said:

MSLP panels look pretty good. CAD sig in place and low pressure to the SW. I'd be perfectly fine with a west track front end thump. Whatever it takes to get on the board with something other than a T

The great ones are the long track storms. Not saying this one is but It feels like the really good ones show their hand early 

[frd]

Well, not everyone is optimistic about December, and the winter in general, regardless of the recent developments.

Here is a very recent update from Isotherm. I brought this over from 33 if anyone is interested.   

from Isotherm:

<<<

[1] The recent storm largely behaved pursuant to expectations, favoring significance across the interior Northeast, with generally minor, 1-3" amounts along the I-95 corridor. The key dilemma was the relatively northerly location of the z700/850 and concomitant lows, which yield maximum felicitous forcing/lift and snow growth approximately 100 miles to the north; hence, the historical snowfall near Albany is not surprising. The boundary layer warmth was an issue for the coast, due in part to poor forcing, in concert with climatological issues [early season]; sporadic banding is insufficient to maintain the necessary evaporative cooling processes as well.

 

[2] Pursuant to conversations hitherto, between myself and others such as @Bring Back 1962-63 and @Tamara, the negative NAO episode was quite ephemeral. The intraseasonally/extratropically forced perturbation yielded a transient diminution in the NAO from November 24th-November 30th, and both the AO and NAO are now strongly positive, in accordance with the base state forcing [and the variables underpinned in my NAO formula].

 

[3] Recent +EAMT episode will yield the ridge spike downstream, as evinced on medium range modelling; however, the underlying predilection will be for premature amplification and thus a continued propensity for hostile storm tracks for the East Coast/I-95 corridor. The aperiodic NPAC ridge spikes were highlighted in my outlook for December [and also repeated appearances during the winter], but the angular momentum transports will continue to promote circum-global sub-tropical ridging. FT has declined materially, and overall, the torque budget should remain near parity for the medium term, as GWO circuits again through the null.

 

[4] Latest QBO value is slightly over +5 for November, again, pursuant to my expectations that this would be a slow descent of easterly shear stress. We have now fallen behind the pace of 2004, and it is unlikely to transition easterly until the end of January or later. This will have ramifications as far as persistently countervailing attempts at protracted blocking. 

 

[5] The pattern, from a sensible weather sense, should promote cold over the Mid-west/Plains, and surges of mild air pre-storm along the East Coast. The structures overall should be generally unpropitious/hostile to coastal significant snowfalls.

 

[6] Recrudescence of lower geopotential heights near Alaska is expected following this EAMT induced ridge spike. Concomitantly, the NAM/NAO should remain generally positive throughout December. Hadley and walker cell behavior continues to operate in accordance with my initial thoughts several weeks ago.

 

[7] Note, that the MJO was a largely minor component of my outlook, and the fact that it may be stationary over the IO for awhile does not impact the likelihood that December finishes warmer than normal. I still think the departure estimates set forth are reasonable.

 

[8] Eventually, the MJO will regain coherency, as it propagates eastward [late December]. 

 

[9] Current ECMWF guidance indicates a fairly rapidly intensification of the stratospheric polar vortex in the medium term. Whether that happens or not --- is not dispositive as it pertains to the tropospheric structures.

 

Summary: First, as a general caveat, to ensure to readers that I am not engaging in the very confirmation bias against which I impugn, here is what could enable to a faster transition into sustained winter pattern than I delineated in the outlook: Since it is unlikely to receive assistance from the QBO in a material way for awhile in my view, the earlier assistance must have provenance in the tropical troposphere. A very potent MJO circulation through 6-7 in late December, ideally in concert with highly anomalous EAMT, would engender a significant momentum induction and further elicit rossby wave propagation poleward. This would, a priori, disrupt momentum budgets enough, in tandem with material SPV disruption, to loosen the effects of the stronger than average tropospheric vortex.

 

However, the likelihood of that occurring is currently low, and the present base state momentum transports and forcing backdrop should continue to promote a +AO/NAO in the means. Spasmodic NPAC ridge spikes should deliver bouts of arctic/polar air, but unfortunately, the storm track should continue to be unfavorable for coastal areas. And I do not see any indication of this tendency reversing for the foreseeable future. As seen with the recent storm, I believe this tendency will persist, re: favoring interior Northeast. All in all, everything appears to be on track, at least from the standpoints of myself and a few others who I know accord with these thoughts. I realize this is an unpopular interpretation, but it is my objective interpretation of the pattern, and no one can unequivocally claim they know what will transpire at this time.

 

>>>>>

 

 

[CAPE]

36 minutes ago, leesburg 04 said:

The great ones are the long track storms. Not saying this one is but It feels like the really good ones show their hand early 

It could end up some sort of messy front end thump deal for western areas. Not bad for favored locations, but at this juncture the look on the ensembles gets a meh from me. Lets see how it evolves over the next several days. Long way to go.

[CAPE]

34 minutes ago, frd said:

Well, not everyone is optimistic about December, and the winter in general, regardless of the recent developments.

Here is a very recent update from Isotherm. I brought this over from 33 if anyone is interested.   

from Isotherm:

<<<

[1] The recent storm largely behaved pursuant to expectations, favoring significance across the interior Northeast, with generally minor, 1-3" amounts along the I-95 corridor. The key dilemma was the relatively northerly location of the z700/850 and concomitant lows, which yield maximum felicitous forcing/lift and snow growth approximately 100 miles to the north; hence, the historical snowfall near Albany is not surprising. The boundary layer warmth was an issue for the coast, due in part to poor forcing, in concert with climatological issues [early season]; sporadic banding is insufficient to maintain the necessary evaporative cooling processes as well.

 

[2] Pursuant to conversations hitherto, between myself and others such as @Bring Back 1962-63 and @Tamara, the negative NAO episode was quite ephemeral. The intraseasonally/extratropically forced perturbation yielded a transient diminution in the NAO from November 24th-November 30th, and both the AO and NAO are now strongly positive, in accordance with the base state forcing [and the variables underpinned in my NAO formula].

 

[3] Recent +EAMT episode will yield the ridge spike downstream, as evinced on medium range modelling; however, the underlying predilection will be for premature amplification and thus a continued propensity for hostile storm tracks for the East Coast/I-95 corridor. The aperiodic NPAC ridge spikes were highlighted in my outlook for December [and also repeated appearances during the winter], but the angular momentum transports will continue to promote circum-global sub-tropical ridging. FT has declined materially, and overall, the torque budget should remain near parity for the medium term, as GWO circuits again through the null.

 

[4] Latest QBO value is slightly over +5 for November, again, pursuant to my expectations that this would be a slow descent of easterly shear stress. We have now fallen behind the pace of 2004, and it is unlikely to transition easterly until the end of January or later. This will have ramifications as far as persistently countervailing attempts at protracted blocking. 

 

[5] The pattern, from a sensible weather sense, should promote cold over the Mid-west/Plains, and surges of mild air pre-storm along the East Coast. The structures overall should be generally unpropitious/hostile to coastal significant snowfalls.

 

[6] Recrudescence of lower geopotential heights near Alaska is expected following this EAMT induced ridge spike. Concomitantly, the NAM/NAO should remain generally positive throughout December. Hadley and walker cell behavior continues to operate in accordance with my initial thoughts several weeks ago.

 

[7] Note, that the MJO was a largely minor component of my outlook, and the fact that it may be stationary over the IO for awhile does not impact the likelihood that December finishes warmer than normal. I still think the departure estimates set forth are reasonable.

 

[8] Eventually, the MJO will regain coherency, as it propagates eastward [late December]. 

 

[9] Current ECMWF guidance indicates a fairly rapidly intensification of the stratospheric polar vortex in the medium term. Whether that happens or not --- is not dispositive as it pertains to the tropospheric structures.

 

Summary: First, as a general caveat, to ensure to readers that I am not engaging in the very confirmation bias against which I impugn, here is what could enable to a faster transition into sustained winter pattern than I delineated in the outlook: Since it is unlikely to receive assistance from the QBO in a material way for awhile in my view, the earlier assistance must have provenance in the tropical troposphere. A very potent MJO circulation through 6-7 in late December, ideally in concert with highly anomalous EAMT, would engender a significant momentum induction and further elicit rossby wave propagation poleward. This would, a priori, disrupt momentum budgets enough, in tandem with material SPV disruption, to loosen the effects of the stronger than average tropospheric vortex.

 

However, the likelihood of that occurring is currently low, and the present base state momentum transports and forcing backdrop should continue to promote a +AO/NAO in the means. Spasmodic NPAC ridge spikes should deliver bouts of arctic/polar air, but unfortunately, the storm track should continue to be unfavorable for coastal areas. And I do not see any indication of this tendency reversing for the foreseeable future. As seen with the recent storm, I believe this tendency will persist, re: favoring interior Northeast. All in all, everything appears to be on track, at least from the standpoints of myself and a few others who I know accord with these thoughts. I realize this is an unpopular interpretation, but it is my objective interpretation of the pattern, and no one can unequivocally claim they know what will transpire at this time.

 

>>>>>

 

 

Thanks for sharing. Everyone has an opinion, and he seems to know his stuff. That being said, no one truly knows. Ever. Op runs end up wrong a lot in the LR. Ens runs are marginally better. I am content to just sit back and see how things roll going forward. It is what it is, and the pattern evolution seems particularly volatile now, probably a bit more so than normal. Simply put, we just cannot know.

[yoda]

46 minutes ago, C.A.P.E. said:

It could end up some sort of messy front end thump deal for western areas. Not bad for favored locations, but at this juncture the look on the ensembles gets a meh from me. Lets see how it evolves over the next several days. Long way to go.

Gets a meh when its textbook for us?  Wonder what would get a "nice" look from you.

Yes, its 10 days out, but that look is a big storm look as Bob and others pointed out.

[CAPE]

Just now, yoda said:

Gets a meh when its textbook for us?  Wonder what would get a "nice" look from you.

Yes, its 10 days out, but that look is a big storm look as Bob and others pointed out.

It's not textbook for "us" dude. It's a pretty decent look on the ensembles. And the timeframe is approaching mid Dec. You can go ahead and  out if you like. I will reserve judgment. Odds are pretty good we will see an entirely different depiction by 12z tomorrow.

[Bob Chill]

7 minutes ago, yoda said:

Gets a meh when its textbook for us?  Wonder what would get a "nice" look from you.

Yes, its 10 days out, but that look is a big storm look as Bob and others pointed out.

The exact snapshot on the euro was a big storm look. Ens support the idea but they also support rain, mixed, or nothing at all. A lot has to happen first. Once the full latitude trough/front clears then any shortwave zipping along after has potential. We're 5 days min away from models focusing on a discrete shortwave that actually exists. Overall the setup is so-so but it's our next chance so it will get a lot of attention. 

[jaydreb]

Happy Hour GFS is pretty active but wants nothing to do with snow for us FWIW.  

[CAPE]

30 minutes ago, jaydreb said:

Happy Hour GFS is pretty active but wants nothing to do with snow for us FWIW.  

But wait, what has become of the textbook look for us? It's not happening now?

[LP08]

8 minutes ago, C.A.P.E. said:

But wait, what has become of the textbook look for us? It's not happening now?

Not necessarily textbook but some of the right things are there.  Happy Birthday!

 

 

[CAPE]

11 minutes ago, LP08 said:

Not necessarily textbook but some of the right things are there.  Happy Birthday!

 

 

 

Its not an awful look. Not even close to textbook tho. A long way to go and plenty of time for changes- and I am not trying to be a Deb lol- but this is a cutter verbatim on the EPS ens mean. Just in a wait and see mode for me. At this point my guess is this period is a bit too soon for a legit frozen threat for our region.

[yoda]

3 hours ago, WxUSAF said:

Probably not surprising in the era of nondivergent ensembles, but the EPS looks reasonably close to the op euro at D10. GGEM actually looks quite similar too. 

 

3 hours ago, Bob Chill said:

MSLP panels look pretty good. CAD sig in place and low pressure to the SW. I'd be perfectly fine with a west track front end thump. Whatever it takes to get on the board with something other than a T

 

2 minutes ago, C.A.P.E. said:

 

Its not an awful look. Not even close to textbook tho. A long way to go and plenty of time for changes- and I am not trying to be a Deb lol- but this is a cutter verbatim on the EPS ens mean. Just in a wait and see mode for me. At this point my guess is this period is a bit too soon for a legit frozen threat for our region.

Lol

[CAPE]

Oh Yoda...

[yoda]

Just now, C.A.P.E. said:

Oh Yoda...

What?  Both WxUSAF and Bob said the EPS supports the OP.  

Cutters don't give us snow... usually very little.  That 240 image clearly shows snow to ice

[CAPE]

Just now, yoda said:

What?  Both WxUSAF and Bob said the EPS supports the OP.  

Cutters don't give us snow... usually very little.  That 240 image clearly shows snow to ice

lol ok Yoda.

[LP08]

10 minutes ago, C.A.P.E. said:

 

Its not an awful look. Not even close to textbook tho. A long way to go and plenty of time for changes- and I am not trying to be a Deb lol- but this is a cutter verbatim on the EPS ens mean. Just in a wait and see mode for me. At this point my guess is this period is a bit too soon for a legit frozen threat for our region.

I agree that I was a little underwhelmed by the eps H5.  It looks similar to the OP but the TPV bullies out of Canada prior to the supposed window.  I don’t think you are a deb at all, I just am an optimist and obviously still learning a bunch.

 

This also jumped out at me.  Consistent signal for a precip event but little to no snow on the means (all caveats about ensemble mean snow aside.

[frd]

18 minutes ago, C.A.P.E. said:

Its not an awful look. Not even close to textbook tho. A long way to go and plenty of time for changes- and I am not trying to be a Deb lol- but this is a cutter verbatim on the EPS ens mean. Just in a wait and see mode for me. At this point my guess is this period is a bit too soon for a legit frozen threat for our region.

Fits the recent theme of transient blocks and in and out cold during non-peak climo here. No real surprises. And, as some have mentioned,  expect variability for a good portion of the month. We need a sustained -NAM to have real threats.

I agree about the cutter outcome. However, things are progressing towards the cup being half filled. 

[Bob Chill]

Just so we're on the same page... Unless there's a transient 50/50 or a very lucky track, the general setup favors a west track by a good margin. Ops and ens are showing a pretty decent cold hp to the north and a decent cad signal. Get something to come at us from the TN valley with a departing HP to the north and it's one of the most common ways we get a light or moderate event but not all snow. 

Last 2 gefs runs support the general idea as does the eps. 

 

All we can do is discuss the potential in general terms. This is the best shot at winter wx I've seen so far. It's flawed and unlikely to be all snow if it snows at all. No reason to poo poo it or go all in yet.

[frd]

2 hours ago, C.A.P.E. said:

Thanks for sharing. Everyone has an opinion, and he seems to know his stuff. That being said, no one truly knows. Ever. Op runs end up wrong a lot in the LR. Ens runs are marginally better. I am content to just sit back and see how things roll going forward. It is what it is, and the pattern evolution seems particularly volatile now, probably a bit more so than normal. Simply put, we just cannot know.

For sure, this December presents many challenges and there are more diverse forecasts out there than typical. No one really knows for sure. 

Isotherm may be correct, as the month is only 3 days old. 

[frd]

@psuhoffman hearing some mets, including Webb talking about the first indications that the IOD may begin to weaken soon. 

HM stated it does not have go completely away, ( which is good because  I know it will take a lot of time to do so ) but just not be as dominant.

Webb feels it weakens month end, and we may start to reap the benefits as early as mid Jan as the focus of tropical forcing becomes more favorable. He stated if that happens it could have rather significant implications. Based on the context he stated his reply,  I am rather sure he means cold and snow-wise.