December 2019 Med/Long Range Disco

[poolz1]

Both gefs and especially the eps have some weak +heights over Greenland just 2 days before this D10ish potential. As jumpy as models are with predicting the NAO domain it remains a big wildcard imo. A delay in breaking this ridge down or maybe it’s stronger to begin with? Possibly the epo ridge extends into the NAO region. Either could force the TPV to be more of a block than modeled.

Probably still a west track but maybe an earlier transfer. Will be interesting to see how things trend with the orientation of the epo ridge and any +heights over GL.

[nj2va]

As the month progresses, we continue to get into more favorable conditions where we don’t need a perfect setup to score (I know, breaking news folks).  Even if it cuts (which that setup supports), we could certainly start as frozen.  Would be nice to get on the board.  

Seems silly to parse details this far out but nothing else to analyze now...

[Ralph Wiggum]

4 hours 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.

 

>>>>>

 

 

I have the utmost respect for Tom and his knowledge of atmospheric science and meteorology. But I couldnt help but chuckle while reading this as I pictured Tom in a fitted suit in court as a paralegal presenting his case to the judge and jury. Very professionally presented!

[40/70 Benchmark]

4 hours 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.

 

>>>>>

 

 

1-3" along I95?

Boston had over 7"...our outlooks are significantly different.

[frd]

25 minutes ago, 40/70 Benchmark said:

1-3" along I95?

Boston had over 7"...our outlooks are significantly different.

Yes, that's true Ray, I believe your seasonal outlook is more positive for snow lovers and you were more bullish on December cold risks than most out there. 

The only folks I now that had a normal or even below normal December ( Or seemed more positive about December )  were you, BAMMWX, Analog over at 33 , a met whom posts there, Weather 53 here and HM seemed positive as well. So basically we have two camps on December outcomes. Today even Eric Webb changed his tune as you may be aware. 

If I recall correctly I believe your seasonal progression may vary a bit from Tom's too, in the sense he seems more bullish later on in the season while you are more positive about December and Jan, although I think you have a caveat about Feb and March could turn out better.

So far you are doing well !       

[frd]

This may not be the perfect analogy and forgive me the context it was used in ( top down , or bottom up ) but I read Matt Hugo stating the TPC could topple like a deck of cards in which you unbalance the deck by rotating the cards and it just collapses, once the mass is shifted.  Well, I am  not sure the context here in this post form Anthony but he believes it is vulnerable.  Certainly things are in place presently, and even more so at mid month. to put pressure on the vortex. Even the return of the Sea of Okhotsk Low. 

 

[frd]

2 hours ago, poolz1 said:

Both gefs and especially the eps have some weak +heights over Greenland just 2 days before this D10ish potential. As jumpy as models are with predicting the NAO domain it remains a big wildcard imo. A delay in breaking this ridge down or maybe it’s stronger to begin with? Possibly the epo ridge extends into the NAO region. Either could force the TPV to be more of a block than modeled.

Probably still a west track but maybe an earlier transfer. Will be interesting to see how things trend with the orientation of the epo ridge and any +heights over GL.

The wave breaking outcome ( IF it materializes) may not show up in the modeling till later. Very complex and a huge timing issue. But, even if this attempt fails I believe there is another attempt at a -NAO later in the month. Also hearing some chatter about the pattern so far this past November and presently is similar to the loading pattern that produces a significant -NAO in January.    

 

 

 

[WinterWxLuvr]

3 hours ago, 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

Tn/Ohio valley cutters are probably the most reliable way that I get snow. Seldom all snow but probably my favorite type of event.

[40/70 Benchmark]

5 hours ago, frd said:

Yes, that's true Ray, I believe your seasonal outlook is more positive for snow lovers and you were more bullish on December cold risks than most out there. 

The only folks I now that had a normal or even below normal December ( Or seemed more positive about December )  were you, BAMMWX, Analog over at 33 , a met whom posts there, Weather 53 here and HM seemed positive as well. So basically we have two camps on December outcomes. Today even Eric Webb changed his tune as you may be aware. 

If I recall correctly I believe your seasonal progression may vary a bit from Tom's too, in the sense he seems more bullish later on in the season while you are more positive about December and Jan, although I think you have a caveat about Feb and March could turn out better.

So far you are doing well !       

I think we will have blocking in second half, but of we don't, it will be tough because Pacific should grow more hostile.

[Solution Man]

On 12/2/2019 at 8:00 PM, losetoa6 said:

What a nice stretch of cold per latest Gefs . This is the Ensemble Metrogram for temps...this is a solid 7 day stretch through the end of the run . Yes this is Carroll county airport but for a mean its impressive.  I'm sure there are colder members in the mix . I'll take my chances if verbatim we had 7 days of cold enough air over us or nearby to score a frozen event . Hopefully this is a trend .

Build it... ( The Cold ) 

And they ...( Storms ) will come 

 

 

 

On 12/2/2019 at 8:26 PM, poolz1 said:

@frd  Some positive signs amongst the muddy waters, imo.  The propensity for HLB so far has been decent.  Nothing sustained.....yet.  Aleutian low seems to want to keep forming. No shortage of closed lows traversing the country.  No red flags with the strat and if anything signs are positive.  I know others have mentioned the MJO and the struggle models are having with it.  I think once we get to mid Dec we will see the MJO stopping its flirt with phase 3 and circle back to 8/1.   +IOD is coming down but SSTs still showing it plainly...it will have its say.

Feeling pretty positive about late Dec and Jan....Though, I feel pretty positive every time before I play golf.  Not so much once back to the clubhouse!

A little surprise on the way for the early morning , incoming!

[showmethesnow]

There is just no way that this from wxbell can be the mean or median for snowfall. (note the circled area is mostly from the system that passed in overnight).

 

Not when I see this. 

 

I would say that the top map may be the Control run of the GEFS but even that doesn't make sense. At this point I think something is just wrong with their coding. 

Besides that, there are quite a few good hits in the mix. For those that keep track we are seeing the hits centered roughly on day 8, day 10-11, day 15-16.

[CAPE]

39 minutes ago, showmethesnow said:

There is just no way that this from wxbell can be the mean or median for snowfall. (note the circled area is mostly from the system that passed in overnight).

 

I haven't looked at the mean lately, but clearly whatever issue they were having still exists. When i noticed it, it was only with the GEFS and not the EPS.

[CAPE]

7 hours ago, WinterWxLuvr said:

Tn/Ohio valley cutters are probably the most reliable way that I get snow. Seldom all snow but probably my favorite type of event.

This is what I said on the first post I made about the potential. Given the advertised set up, the cold might hang in long enough for some frozen out your way, but not a look I get too excited over. Yoda was having some parsing issues last night.

[Ralph Wiggum]

So if I am reading this correctly, Isotherm is basically saying a wasted first part of winter with majority non-snow events and a struggle even into the mid portion but turning favorable second half? And Ray is saying favorable first half of winter but a wild card for the second half where he expects the Pac to turn hostile and relying on N Atl blocking to save us? Two of the best and most knowledgeable guys on the boards and two completely different takes. Good reads from both of them lately. 

[showmethesnow]

Some comparing the 7 day mean (DAY 8-15) on the GEFS and the EPS might not see that much of a difference. After all both feature -EPO, +PNA, WAR (western Atlantic ridging), eastern trough/western ridge with just some minor differences. But the slight differences here are key when it comes to what we see with the WAR as well as the EPO to a smaller degree.

 

 

 

But look at what we actually see as far as temps. Striking differences. These looks are the differences between transient cold shots and probably cutters to our west (eps) or sustained deeper cold with transient shots of warmth with systems having a good shot of riding under us and to our east.

 

 

There are several things in play here and it begins with what we see occur with cold shot that enters the central US at roughly day 6. What we are seeing is the EPS is expending most of its energy in driving southward and very little to the east. So we are seeing the cold push deep into the south and yet it quickly withdraws northward giving us a somewhat glancing blow and doing little to break down the higher heights to the NE (WAR). But we aren't seeing that with the GEFS. What we are seeing there is the energy is moving only so far south before it begins pushing eastward. With the smoothing the means provide it isn't really discernible but I do believe that what we are seeing is GEFS keying on splitting the energy dropping down in the NS. First piece drives only so far southward initially  and then as it is retreating back northward it is creating a weakness to the NE as it helps break down those higher heights. The secondary push of the NS is taking advantage of this and moving eastward into that weakness and helps to further breakdown those higher heights to the NE (WAR). This breaking down of the higher heights has ramifications moving forward. 

What we see a few days down the road is that we have another push southward of the NS. Though the timing is off a little between both models if you look at where the mean trough reaches neutral you see a notable difference. Note the EPS is driving the trough deep into the south and it is reaching a neutral state in E Texas. The GEFS on the other hand isn't driving as far southward and is reaching a neutral state over the Mississippi (actually a favored spot to see snow through our region). The differences here are the result of the initial cold push and its effects on the WAR (look at the differences in strength and placement) as well as the greater weaknesses created in the south by the EPS' deeper plunge initially.

***Now I noted above that the EPO played a role here as well but didn't discuss it. What we are seeing here is interplay between it and the WAR through this period. The weaker and further displaced east we see the WAR the more likelihood we see a stronger EPO (and N based +PNA as well). The stronger these features the better the ability to deliver cold air in these pushes south by the NS. 

 

At this point IMO everything rides on what we see with the initial plunge of cold. See a EPS type evolution with that feature and I think we struggle to score snow. GEFS solution on the other hand and I believe are chances increase quite a bit and we see a decent stretch of cold. 

***NOTE: If the GEFS' evolution is right with the initial push with the cold it might be worth keeping an eye on energy running up that boundary as it moves through our region (Would all depend on timing as far as possible snows).   EPS, not so much.

 

 

 

 

[frd]

Maybe, as mentioned previously, the start of the less prominent IO standing wave later in the month. 

 

[Isotherm]

11 hours ago, 40/70 Benchmark said:

1-3" along I95?

Boston had over 7"...our outlooks are significantly different.

 

11 hours ago, frd said:

Yes, that's true Ray, I believe your seasonal outlook is more positive for snow lovers and you were more bullish on December cold risks than most out there. 

The only folks I now that had a normal or even below normal December ( Or seemed more positive about December )  were you, BAMMWX, Analog over at 33 , a met whom posts there, Weather 53 here and HM seemed positive as well. So basically we have two camps on December outcomes. Today even Eric Webb changed his tune as you may be aware. 

If I recall correctly I believe your seasonal progression may vary a bit from Tom's too, in the sense he seems more bullish later on in the season while you are more positive about December and Jan, although I think you have a caveat about Feb and March could turn out better.

So far you are doing well !       

 

@40/70 Benchmark - the board I posted that on is geared toward NYC metro, so the 1-3" forecast was specifically for PHL-NYC corridor.

@frd and @Ralph Wiggum, thanks for your comments. And Ralph, that is generally an accurate description of my thoughts. I expect February will be the most conducive, compared to Jan/Dec.

[poolz1]

9 minutes ago, frd said:

Maybe, as mentioned previously, the start of the less prominent IO standing wave later in the month. 

I guess I am a little confused...which doesnt take much.  I thought that the +IOD and resulting standing wave is what is keeping the MJO from rolling through the warm phases?  Doesnt this keep convection in 1/2.  Once the standing relaxes...what is expected?

[frd]

If his formula is correct will be interesting to see the outcomes regarding the warm blob.  I know we are talking degrees here but combined with ice free waters near Alaska may assist in blocking. 

Emanuele Di Lorenzo

@manu_ocean

Ocean & climate scientist. Dad of four. Professor & Director of Ocean Science & Engineering

@GeorgiaTech

.

https://www.dropbox.com/s/xxuft0mmb3qzvzb/DiLorenzo-heatwave-prediction-2020.pdf?dl=0

 

[SnowLover22]

5 hours ago, showmethesnow said:

There is just no way that this from wxbell can be the mean or median for snowfall. (note the circled area is mostly from the system that passed in overnight).

 

Not when I see this. 

 

I would say that the top map may be the Control run of the GEFS but even that doesn't make sense. At this point I think something is just wrong with their coding. 

Besides that, there are quite a few good hits in the mix. For those that keep track we are seeing the hits centered roughly on day 8, day 10-11, day 15-16.

Not sure but I think this site might give a better representation of the mean. 

 

 

It is found at https://weather.cod.edu/forecast/

[Bob Chill]

Just caught up with the overnight runs. My suspicion of the 12z Euro yesterday being too fast (unfortunately) appears to be the case. Plenty of lead time to watch things evolve and we won't even be back in the game until the prog'd cold front pushes through here mid next week.

[jaydreb]

12z GFS has a frozen event at hour 240.  Precip running into cold air damming.  

[Bob Chill]

+PDO continues to slowly build so that's good. That "Nino" though... not lookin so hot. I didn't expect to have Nino conditions this year so not much of a surprise. 

[40/70 Benchmark]

2 hours ago, Isotherm said:

 

 

@40/70 Benchmark - the board I posted that on is geared toward NYC metro, so the 1-3" forecast was specifically for PHL-NYC corridor.

@frd and @Ralph Wiggum, thanks for your comments. And Ralph, that is generally an accurate description of my thoughts. I expect February will be the most conducive, compared to Jan/Dec.

Gotcha.

[WxUSAF]

5 minutes ago, Bob Chill said:

+PDO continues to slowly build so that's good. That "Nino" though... not lookin so hot. I didn't expect to have Nino conditions this year so not much of a surprise. 

Yeah, but the atmosphere is still behaving like one for now. Ride that train, Bob. 

[Bob Chill]

Just now, WxUSAF said:

Yeah, but the atmosphere is still behaving like one for now. Ride that train, Bob. 

I'm all in until I'm out. Luckily there haven't been much if any hints that things go to hell and stay there. OTOH- patience will likely be tested over the next few weeks. Any potential event will need sweet timing as winter wx windows appear to be short lived in progressive flow. But I do agree that flow is active and the southern stream seems prone to get involved. 

I'm hoping the d10+ EPS "bias" we've seen over the last couple years of digging too deep in the SW and pushing cold east too slow is happening right now. I'm not head over heels with ens guidance D7+ but it's far from a shutout look for now. Overrunning is our best chance as it seems like anything amplified is going to pass west of us. 

[WxUSAF]

Speaking of overrunning, gorgeous setup in uber-fantasyland GFS that delivers a modest event, with another on the way at the end.

[Bob Chill]

1 minute ago, WxUSAF said:

Speaking of overrunning, gorgeous setup in uber-fantasyland GFS that delivers a modest event, with another on the way at the end.

The broad conus trough is key. We won't have a deep entrenched cold airmass but we can play with fire on the edges. I hope the gfs/gefs has the right idea versus the steep ridge/trough stuff we're seeing on the euro/eps.  

[psuhoffman]

@Bob Chill @WxUSAF

Was wondering what you think about this regarding the current nino/neutral pac.  In the past enso neutral winters favored above normal snowfall.  But in the last 20 years most of them have been pretty awful. But is that really climate change or more down to the fact that neutral enso years lately have had some other negative pattern driver attached (like a hostile QBO, ugly PDO sst, following a Nina). We haven’t seemed to have many neutrals where the other factors we want were lined up well. This year could be a good test of how the base state in an enso neutral year has changed because with a favorable North Pac SST, coming off a weak nino, high snowcover, North Atlantic Tripoli, favorable QBO phase, this is the type of neutral that historically should skew snowy. Not saying epic year just in the past we would expect normal to above normal snow with this look. But the total fail of neutral years lately makes me wonder.  Curious what others think?

[WxUSAF]

Ha, no idea. It’s all such small sample size statistics and then try and account for a warming climate and who TF knows? Not to mention how much random chance impacts our snowfall vs. places farther north.