Winter 2019-20 Preseason Discussion

[psuhoffman]

1 hour ago, WxUSAF said:

The only thing I see in Cohen’s plot is what looks like a pretty clear upward linear trend over the last 40 years. Whether that’s a climate response or something else, I don’t know. I don’t think there’s been a comparable trend in mean winter AO state.

 

1 hour ago, frd said:

I came across an interesting read a few days ago that showed a very close  correlation between October's  SAI and the following winter's  AO, which revealed a -_AO in the winters following robust October snowfall in the Northern Hemisphere and below 60 degrees North. This correlation came in the time period 07 to 11 the post mentioned.

Problem is since then the correlation has been a erratic at best, and the ensuing winter's AO was not predominantly negative. The overall results were mixed.  

Whether this has to do with the recent sea ice losses, later starts to winters , I am not sure. That is why after 2011 the magic was lost to a degree. Judah did get a lot of press during the winters of 13-14 and 14-15 with the PV visits but by then folks were questioning the validity of the SAI.  

 

It’s possible climate change has eliminated the old correlations and rendered his methodology irrelevant until a new baseline for what normal wrt snowfall advance is and how it impacts the AO is established. 

[psuhoffman]

1 minute ago, mappy said:

need the long-winded post by PSU and this thread is complete. 

Bob Chill Check

Showmesnow Check

Lol

Im trying to “cut down” but I was planning to post my thoughts on Winter very soon, as soon as I can find time to finish looking at some stuff. So you will get it, be careful what you wish for...  but I do like more of what I see now than not.  Of course my thoughts aren’t worth a whole lot.  

[mappy]

1 minute ago, psuhoffman said:

Lol

Im trying to “cut down” but I was planning to post my thoughts on Winter very soon, as soon as I can find time to finish looking at some stuff. So you will get it, be careful what you wish for...  but I do like more of what I see now than not.  Of course my thoughts aren’t worth a whole lot.  

you don't give yourself nearly enough credit. hope you and the family have been well!

[WxUSAF]

8 minutes ago, psuhoffman said:

 

It’s possible climate change has eliminated the old correlations and rendered his methodology irrelevant until a new baseline for what normal wrt snowfall advance is and how it impacts the AO is established. 

He actually responded on Twitter to my question about the linear trend and linked a paper he wrote in 2012 on that idea. Haven’t read it yet. 

[Bob Chill]

If you look at Nov 2013&14 npac SSTA plots they look pretty similar to this year. . This year looks like a blend of those 2 years (especially ENSO regions) and I find it encouraging.

Here's current, Nov 2013 and 14 SSTA plots:

 

 

 

Yea, 2013-15 period featured a pretty nasty +AO/NAO but the Pac doesn't really drive the high latitudes as much as it drives the longwave pattern in the mid latitudes so jumping to the conclusion that the similarities to 13&14 means the AO/NAO are going to suck is a mistake. Current ens 5 day mean height patterns look a lot like Nov 2014. I don't think all of this is coincidence. If current ens guidance is correct, at least a portion of Nov will look very similar to Nov 2014. Looking at the GEFS panel below you can see how nice the Pac is setup to continue the trend towards a +PDO. If this is the dominant pattern in Nov then the npac SSTA configuration is going to look very good. 

 

 

 Still a month out from game time but you can't help but to think that the Pac/NA pattern will likely feature a coupled -EPO/+PNA at times this season. 2014 looked great in Nov and fell completely apart in Dec but no 2 years are ever the same. Not to mention that Dec 2014 was only a relaxation before the same pattern as Nov set up and carried through all the way into March. I can visualize the possibility of getting a favorable Pac/NA pattern similar to the 2013-15 stretch but what could really make it interesting is if the AO/NAO are also more favorable instead of the complete opposite of what we want to see. 

Analogs are good tools to use but where people make the biggest mistake is assuming the same outcome as a previous analog. The atmosphere is way too complex to work that way. Take 13-14 for example. The mean height pattern through met winter was uncannily similar to 93/94. But sensible wx was MUCH different in our yards. Instead of a mix/icy redux of 93/94 we ended up getting snowed on start to finish. Personally, I'd MUCH prefer NOT to get a 93/94 or 13/14 upper level pattern redux because it's not a good pattern for our region to get snowfall even though one of those years was prolific. However, give me a 13/14 or 93/94 redux with SOME semblance of a -AO/NAO and I'll root for that all fookin day. 

[Mr. Kevin]

9 hours ago, Bob Chill said:

If you look at Nov 2013&14 npac SSTA plots they look pretty similar to this year. . This year looks like a blend of those 2 years (especially ENSO regions) and I find it encouraging.

Here's current, Nov 2013 and 14 SSTA plots:

 

 

 

Yea, 2013-15 period featured a pretty nasty +AO/NAO but the Pac doesn't really drive the high latitudes as much as it drives the longwave pattern in the mid latitudes so jumping to the conclusion that the similarities to 13&14 means the AO/NAO are going to suck is a mistake. Current ens 5 day mean height patterns look a lot like Nov 2014. I don't think all of this is coincidence. If current ens guidance is correct, at least a portion of Nov will look very similar to Nov 2014. Looking at the GEFS panel below you can see how nice the Pac is setup to continue the trend towards a +PDO. If this is the dominant pattern in Nov then the npac SSTA configuration is going to look very good. 

 

 

 Still a month out from game time but you can't help but to think that the Pac/NA pattern will likely feature a coupled -EPO/+PNA at times this season. 2014 looked great in Nov and fell completely apart in Dec but no 2 years are ever the same. Not to mention that Dec 2014 was only a relaxation before the same pattern as Nov set up and carried through all the way into March. I can visualize the possibility of getting a favorable Pac/NA pattern similar to the 2013-15 stretch but what could really make it interesting is if the AO/NAO are also more favorable instead of the complete opposite of what we want to see. 

Analogs are good tools to use but where people make the biggest mistake is assuming the same outcome as a previous analog. The atmosphere is way too complex to work that way. Take 13-14 for example. The mean height pattern through met winter was uncannily similar to 93/94. But sensible wx was MUCH different in our yards. Instead of a mix/icy redux of 93/94 we ended up getting snowed on start to finish. Personally, I'd MUCH prefer NOT to get a 93/94 or 13/14 upper level pattern redux because it's not a good pattern for our region to get snowfall even though one of those years was prolific. However, give me a 13/14 or 93/94 redux with SOME semblance of a -AO/NAO and I'll root for that all fookin day. 

Hi Bob. I have a question. Did we have a positive IOD in 13/14 and 14/15 winter like we have so far? I am wondering why after November 2014 it warmed up dramatically until end of January 2015.

[frd]

Week 44 N Hemisphere Snow Cover just updated,  and we are very high compared to previous week 44 over the past 20 years. 

Yesterday we gained positive anomalies on both sides of the pole ( link below )  

Southern Canada did very well over a large region. 

If anything the Siberian high should be aided by the vast snow cover over there.  

 

Row	Year	Week	N. Hemisphere	Eurasia	N. America	N. America (no Greenland)
1	2019	44	31.89	18.41	13.48	11.33
2	2019	43	28.69	16.50	12.19	10.04
3	2019	42	23.49	14.29	9.20	7.05
4	2019	41	18.05	9.66	8.39	6.24
5	2019	40	14.63	8.16	6.47	4.32
6	2019	39	8.91	3.52	5.39	3.24

 

Wow,  positives on both sides of the pole. Looking great so far ! 

https://climate.rutgers.edu/snowcover/chart_daily.php?ui_year=2019&ui_day=307&ui_set=2

 

 

More to come for NA

 

 

 

 

[WxUSAF]

Judah’s GEFS snow maps are the absolute worst lol

[Bob Chill]

12 hours ago, Mr. Kevin said:

Hi Bob. I have a question. Did we have a positive IOD in 13/14 and 14/15 winter like we have so far? I am wondering why after November 2014 it warmed up dramatically until end of January 2015.

I'll have to defer on your question. I don't know enough about the IOD and how it affects our sensible wx to give a qualified answer. I generally stick pretty close upstream with mid latitude patterns. The Pac basin is the furthest upstream I look at along with the high latitudes. 

[Bob Chill]

I pulled some quick data with enso neutral and +PDO winters since 1960. Can't hang your hat on a single index but the group as a whole shows the odds of a total dud are pretty low. A few of the years were solid. The takeaway is near normal snowfall is favored with a better chance at AN than a disaster.

Here's DCA for the years I pulled:

1960-61 - 40.3"

1969-70 - 14"

1980-81 - 4.5"

1981-82 - 22.5"

1985-86 - 15.4"

1992-93 - 11.7"

1993-94 - 13.2"

2003-04 - 12.4"

2013-14 - 32"

2014-15 - 18"

Not a bad group right? It's also notable that all the big snow nina and nino years are in the mix (82-83, 86-87, 95-96, 02-03, 15-16). It's almost a guaranty that a mod or strong nino will have a +PDO because warm enso affects the north pac basin. OTOH- nina's generally feature a -PDO but 95-96 was very positive (very unusual year with unusual results). 

So why does a +PDO help us? There's a chicken or egg argument on what causes what (SST or upper level patterns driving the bus?) but for our purposes it doesn't really matter. We just need to root for a strengthening +PDO and let the chips fall. From the limited data it appears that a strengthening +PDO is better than a weakening one and that makes sense because the pattern that drives a strengthening PDO features a trough in the wpac, ridge in the epac/north america, and trough in the east half of the conus. The correlation has far too small of a sample size though so no spiking footballs on whether or not a strengthening +PDO is better. Logic says it is but this stuff is too complicated for a narrow focus like that.  

Right now the PDO is mostly neutral but the upcoming pattern over the next 2 weeks will likely shift things enough to push the PDO positive. If it does then just keep watching for a continuation of the +PDO and let the chips fall. It could be an important signal as we head into Dec.  

 

[H2O]

Bob with the analog porn

[WxUSAF]

FWIW, the good folks on that OTHER wx forum based in a SE PA city have a very similar view RE: neutralish ENSO, +PDO winters and snowfall. Near normal with better chance of boom than bust. 

[Maestrobjwa]

1 hour ago, Bob Chill said:

Not a bad group right? It's also notable that all the big snow nina and nino years are in the mix (82-83, 86-87, 95-96, 02-03, 15-16). It's almost a guaranty that a mod or strong nino will have a +PDO because warm enso affects the north pac basin. OTOH- nina's generally feature a -PDO but 95-96 was very positive (very unusual year with unusual results). 

Okay, now....is there any correlation to low solar with this (the +PDO) I wonder? Because that year was so unusual...coincidence it was at or near a solar minimum? (I know there's a theory of the minimum being responsible for all the blocking). The season is always a head scratcher because it was so anomalous!

[CAPE]

Fwiw, the Nov 1 edition of the Euro Seasonal is out. Looks like a continuation of the good look in the EPO/PNA domains, and no red flags in the NA. Gets pretty ambiguous with the height anomalies after the first month, but looking at height lines the NAO is probably neutral-ish for the most part. Temps are below avg for November(obvious) and verbatim look normal for Dec, Jan, and Feb.

[frd]

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

Fwiw, the Nov 1 edition of the Euro Seasonal is out. Looks like a continuation of the good look in the EPO/PNA domains, and no red flags in the NA. Gets pretty ambiguous with the height anomalies after the first month, but looking at height lines the NAO is probably neutral-ish for the most part. Temps are below avg for November(obvious) and verbatim look normal for Dec, Jan, and Feb.

Hearing the spread of NAO solutions are larger in this update , going by what Matt posted. I have not seen it first hand. 

Sounds like the Pac remains good, which makes sense and increase my confidence in colder risks/outcomes.  

Will be interesting tracking what the PDO does,  according to Bob's recent posts, maybe going more positive.  A + 1 PDO in December ( from Don S ) certainly makes a colder December outlook more plausible based on his research.  I am still riding the +PMM for a cold December , even though it is not as high as 3 weeks ago I believe.    

 

 

 

[frd]

@poolz1

So much to look at these days, very exciting times.  The Strat takes a back seat to sensible weather and real time events but this is worth mentioning.

Speculation on my part, but  maybe this either decreases any moderation period ( even though the outcome is uncertain and lag period as well ) and potentially increases risk of more significant weather events here. 

As Tip in NE forum mentioned any strat helped - AO outcome may simply get lost in a season of naturally occurring -AO tendencies. 

So far, so  good. 

 

 

 

[CAPE]

1 hour ago, frd said:

Hearing the spread of NAO solutions are larger in this update , going by what Matt posted. I have not seen it first hand. 

Sounds like the Pac remains good, which makes sense and increase my confidence in colder risks/outcomes.  

Will be interesting tracking what the PDO does,  according to Bob's recent posts, maybe going more positive.  A + 1 PDO in December ( from Don S ) certainly makes a colder December outlook more plausible based on his research.  I am still riding the +PMM for a cold December , even though it is not as high as 3 weeks ago I believe.    

 

 

December looks neutral to me, Jan looks Positive, and Feb- who knows. The fact that Nov and Dec look fine is good enough given the skill of a seasonal model. Jan may look entirely different on the next edition in a month.

[Bob Chill]

1 hour ago, Maestrobjwa said:

Okay, now....is there any correlation to low solar with this (the +PDO) I wonder? Because that year was so unusual...coincidence it was at or near a solar minimum? (I know there's a theory of the minimum being responsible for all the blocking). The season is always a head scratcher because it was so anomalous!

I doubt solar has much to do with it. A lot of year over year variability can't be explained. It can be speculated about but often has no tangible explanation other than weather being weather. Why was 93/94 a rainy/icy/mixed mess and 13/14 a prolific snow maker? There's no real way to pinpoint why they were so different. However, up in the NE, both of those years were great but it snows a lot more up there and an amplified progressive pattern works a lot better further north.

The MA is right on the edge between good and bad snow climo so the needle wavers back and forth just cuz it can. Sometimes we're on the right side and other times we're on the wrong side of marginal patterns. That's just how life is living here. No sense trying to make sense of something that can't be made sense of. 

[JakkelWx]

UGH!!

 

[CAPE]

19 minutes ago, JakkelWx said:

UGH!!

 

Latest CFS runs agree. Torches us Dec through Feb. Cancel winter I guess..oops hold on-  it says March will be rockin'!!

[frd]

24 minutes ago, JakkelWx said:

UGH!!

 

 

This conversation is too good to pass up . Webb makes a good reasoning for us to have a warm December and if we get the ENSO 1.2 to warm well it could get ugly. 

For every action there is a reaction.  

 

 

@bamwxcom

·

41m

 

Replying to

@webberweather

Things are a lot different this year though. I don’t think we’re looking at the traditional Dec torch. Reasoning is winded but just looking at the PV alone, tropical forcing and QBO/solar cob argues this year has legit chances at atleast slightly colder than normal.

 

BAMWX

@bamwxcom·

38m

 

No denying the risk and general climo of course but if I were to bet against all that it would be this year. If ENSO 1.2 can stay cool that will help too along with generally -AAM. That’s our idea atleast

 

hope all is well! -Michael

Eric Webb

@webberweather·

35m

 

Oddly enough, when you remove the strong NINOs w/ huge NINO 1-2 anoms from that subset, the warm signal gets stronger in Dec. I have a hunch we're probably going to hit a brick wall at some pt once the tropical forcing shifts back into the Indian Ocean. http://atmos.albany.edu/facstaff/roundy/waves/RMMphasecompslp500ht.html…

 

 

BAMWX

@bamwxcom·

32m

 

That is certainly interesting. The correlations since 2000 argue an Eastern Us Trough. The EPS/CFS weeklies also stall the MJO in 8-1-2 largely for DEC. If we torch this year I think it may never be possible to get cold in DEC again

 

 

 

 

 

Eric Webb

@webberweather·

24m

 

MJO phases 8-1-2 are cold at lag = 0 in the east-central US, but w/ positive lag in NDJ, we're often mild or torching. I also have reservations about NINO 1-2 staying negative for too much longer.

 

 

 

 

 

Eric Webb

@webberweather

·22m

 

Interesting forecast nonetheless, I hope I'm wrong because I've gotten completely sick & tired of warm Decembers around here, 8 in a row and counting in NC.

 

 

[CAPE]

I always wonder who these Twitter self promoter types are and why I should value their opinions. So Webb is a frustrated snow weenie from NC. Now I got it.

[H2O]

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

I always wonder who these Twitter self promoter types are and why I should value their opinions. So Webb is a frustrated snow weenie from NC. Now I got it.

I bet if you went and looked for a similar type tweet from last year it was all hype for a cold winter.  And we know how that worked out.  I pay no mind to these things that try to say what it will be like in 3 let alone 1 month ahead

[Bob Chill]

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

I always wonder who these Twitter self promoter types are and why I should value their opinions. So Webb is a frustrated snow weenie from NC. Now I got it.

Long range forecasting outside of easy enso years has been pretty abysmal both in model land and met or enthusiast forecasts for years (I know u know this well). It usually ends up looking something like this at the end of the season: "I got the fill in the blank  correct BUT....". But = the atmosphere does what it does best and does a lot of things that nobody predicted and in many cases it was never even discussed at all.  

I'm not trying to insult anyone because I really appreciate the effort from the skilled seasonal forecasters. It's just not possible to consistently predict weather months in advance unless enso is the primary driver so skill is at least part luck and sometimes mostly luck. 

I could bat .750 in our area just by saying above normal temps and below normal snow every single winter. That's not really skill. It's basic climo and sticking with simple climo is boring but effective. 

[psuhoffman]

1 hour ago, C.A.P.E. said:

I always wonder who these Twitter self promoter types are and why I should value their opinions. So Webb is a frustrated snow weenie from NC. Now I got it.

He may be right wrt a warm December, definitely has been the trend lately. But the thing is in the last decade the years we had a good cold period in November and or part of December then a warmup the pattern did flip colder again at some point and we had a decent winter or better. Years it torched November and December mostly went on to be duds. So regardless if the snap theory (and I’m not totally buying it) this is a good sign imo. 

[CAPE]

8 hours ago, psuhoffman said:

He may be right wrt a warm December, definitely has been the trend lately. But the thing is in the last decade the years we had a good cold period in November and or part of December then a warmup the pattern did flip colder again at some point and we had a decent winter or better. Years it torched November and December mostly went on to be duds. So regardless if the snap theory (and I’m not totally buying it) this is a good sign imo. 

He may very well be right. I guess I was gently bitching about all the posts featuring opinions by random folks on twitter who I don't know, and have no idea why I should care what they think(excluding someone like HM). Maybe i'm  just getting old lol,  but I know where to find Twitter if I "need" it. I don't mind a few twitter based posts here and there that add value, and frd does a nice job in general as he adds in his own take, and doesn't simply plop tweets into a post. 

[poolz1]

You are definitely getting old... Lol. I'm getting old too. My teenage daughter reminds me daily!

I use Twitter for weather, sports, and fishing. I have no friends on Twitter and never post. But, I follow most of the folks that frd follows and I can say that none of the Twitter posts in here from frd are from "weenies." The previous thread posted was from well educated, level-headed and reputable folks. If you follow the right people Twitter is like the weather forum for a lot of professional Mets. Not everything is meant to be gospel... Just professionals tossing out ideas and thoughts.

Sent from my SM-G973U using Tapatalk

[frd]

 

I am surprised DT posted this as he loves the Euro,  but then again he has a colder winter outlook. 

In regards to the seasonal as well, wondering  what is more difficult for the seasonal models to predict,  the precip tendencies or the temps ?

I would imagine one is related to the other,  and both could be difficult to forecast.  The signal for precip has been there along the East Coast. 

Also, still reading things about the NAO for Dec. As @C.A.P.E. posted. Hearing the spread for a +NAO  in  December has been reduced. 

Looks like Jan has the greatest indication of a positive NAO  from some sources and hence has strongly shifted . 

This entire sequence of events is remarkable in itself because if a forecaster can call the turning point of the NAO correctly , or the mild period coming up that can make his or her seasonal forecast golden. 

Maybe in the NE , including our region,  we get the NAO to go negative in December ( still awaiting on HM's call of a more so negative NAO later in month ) That might help if we lose the Pac. If we get the - NAO in December does it then last until early Jan 20? If so, then maybe the Pac improves and lessens the need for the -NAO in Jan . 

Honestly,  if the Pac is as good as it seems like it wants to be this season, well we will not need the help of a -NAO  as much . Some here are more interested in the rises and falls of the NAO versus a continuous trip well above neutral.  These relates to possible storm periods. 

All these things enter the picture as to how the month of December, Jan and Feb will go. Interesting times ahead. For every action there is a reaction. Call the first action correctly and then you might be more likely to call the next couple months correctly. 

I see some professional forecasters are still waiting to release their seasonal forecasts. Why ? I think they are again searching for the sequence and timing the evolution of the current pattern, and the reaction  after this anomalous cold period coming up.  It is not very easy at all.   

 

 

 

[Bob Chill]

@frd

From what I've watched over the years, a -NAO is most important during Dec so if we're going to get a good blocking month let it be December. Next best is Feb. Blocking in Jan can be an easy recipe for dry and cold (SE loves this setup though). Also, if the winter's base state is a coupled PNA/EPO ridge then we probably don't want a strong -NAO at any time. SNE definitely doesn't. As always it's a balance. I'd prefer many periods of the -NAO pressing and retreating but what I prefer doesn't mean jack. lol

[psuhoffman]

9 minutes ago, Bob Chill said:

@frd

From what I've watched over the years, a -NAO is most important during Dec so if we're going to get a good blocking month let it be December. Next best is Feb. Blocking in Jan can be an easy recipe for dry and cold (SE loves this setup though). Also, if the winter's base state is a coupled PNA/EPO ridge then we probably don't want a strong -NAO at any time. SNE definitely doesn't. As always it's a balance. I'd prefer many periods of the -NAO pressing and retreating but what I prefer doesn't mean jack. lol

I've seen data that indicates March might have the highest correlation between the NAO and cold/snow here BUT...that probably is because you need so much to line up to get snow here that late.  That doesn't necessarily mean the NAO influences the pattern more then.,  In 2002 we got NAO help early and allowed us those December snows, then the PAC took over the rest of the winter.  Something similar this year would be acceptable.