eduggs

5 hours ago, MANDA said:

Nope, it sure ain't if it verifies.

It's actually possible to have a significant snowstorm before or after a "bad" Pacific flow pattern and get that 5-day average look. Heck even jumbled, partially interfering shortwaves could blunt the Pacific influence and still produce a time-smoothed result to match that graphic. LR multi-day-averaged anomaly maps are ensemble-and time-averaged. That produces a very low resolution, continental-scale overview. I think it's important to understanding what we're looking at before we try to interpret it.

The 18z GFS has a parade of between 6 and 10 successive shortwaves (depending on how you distinguish them) that partially interfere with each other over the next 10 days to prevent any significant local storm development. This highlights one of the problems of using LR time-blended height anomalies to try to identify favorable or active "periods." The averaged anomalies look interesting over the next week, but as usual, everything comes down to the evolution and orientation of the height fields. The actual weather could end of being quite boring depending on the fine details of wave interaction.

I prefer Walt Drag's method of threat identification mostly keeping inside of 10 days using a mid-range multi-model super-ensemble focusing on QPF and temperature distributions. To my knowledge Walt doesn't mention climate indices or height anomalies. And he doesn't frequently trigger annoyed disappointment with a lot of LR false alarms. 

23 minutes ago, psuhoffman said:

I mean this with no snark, just trying to help. But that map there isn’t indicative of a good snow setup for us. 

Its subtle but the +NAO and ridging in the western Atlantic near 50/50 makes a big difference. If there was a trough there then that’s a great look. 
 

But ignore the colors and look at the flow. It’s straight out of the south. Blue over us doesn’t = good snow pattern. Think basic wave physics. Any wave approaching from the west will have a southerly flow ahead of it.  If we’re going to have an amplified trough like that we need a mechanism to suppress the southerly flow. Blocking!!!  It’s not there so any approaching wave in that look it very likely to cut and drive the thermal boundary way northwest of us. Add in a lack of any antecedent cold and that was never a good look. I say this with no ill intent just trying to help for future reference, but looking at that and thinking it’s good is user error. 
 

There are ways to snow without blocking but we would need a more progressive less amplified long wave configuration than that (the broad bowl @Bob Chilland @CAPE are always referencing or a trough axis further east and get lucky with a perfect timed late phase and tuck… only way that look there works is either an arctic antecedent airmass then maybe a front end thump or a lucky secondary development but both of those are long shot fluke type things.  
 

That look above is however a good loading pattern to get to a better pattern a few days later  that amplified trough will move northeast and set up the suppression we need for the next wave or two to have a shot.  With luck the wave break can even improve the NAO.  So people were right to look at that as positive in the longer term but wrong to think that wave was ever a real threat.  

 

 

I was merely pointing out that even when MR or LR model ensemble forecasts verify a high degree of accuracy with respect to the general continental-scale height field, there is typically too much uncertainty at that range to make regional weather forecasts. This was in reference to someone suggesting a 5-day old GEFS chart matched tomorrow's height field pretty well... and also references from a week ago suggesting this period could produce a wintry event.

Snapshot anomaly charts should never be used by themselves for synoptic forecasting. IMO they are massively overused and the result of an increase in interest in climate indices and LR forecasting.

33 minutes ago, WinterFire said:

 This is the same time from today’s 18z GFS. Not a lot of daylight between them, I don’t think?

That's why anomaly charts are overrated. People assume blue always means good. I can't count the number of times with all of my fingers and toes over the past two winters that 10 day+ anomaly charts gave a false impressions of a favorable period. It's much better to simply loop the raw 500mb heights with vorticity to observe the progression. But people have developed this bad habit of obsessing over the anomalies. 

2 hours ago, kazimirkai said:

Snowfall to date. Looking back at maps from the same date in other years, it seems like there hasn't been a winter this inactive across the country since 2015-2016.

The "trace" threshold makes the southern fringes look quite a bit inflated 

2 hours ago, EastonSN+ said:

I personally go off of experience and living through the 80s/90s as well as the 2000s.

I have vivid memories of the late 80s and 90s and the experience was just like the last 5 winters for me. Why do the last 5 winters have to be a new reality when we have seen these setups and frequencies in the past? In my opinion we have a long period of time to wait and collect data until we can know the answer.

Maybe a climatologist can publish and in depth paper on the differences between that 30 year period and the last 5 years. Also, 1955 through 1969 compared to 2000 through 2018. In GUESSING, I would have to think that they would match up relatively well (and so nobody thinks I do not believe it's getting warmer out, baseline temperatures adjusted up for both periods by whatever the number is).

In the meantime there will always be disagreements between the audience members, which is healthy and leads to debates and knowledge growth. 

My stance is per the above based on experience, and I am open to change as time goes by. At the current time, living through both periods, I am not at the point yet where I can agree we have past a point where we have shifted to new pattern regimes.

I like your write up.

I also lived through the 80s and 90s. I remember several frustratingly low snow years. I agree from a snow perspective it's impossible to know for sure how much influence a changing base state has vs. just being in a bad stretch. One thing that does stand out, however, about recent years is the warmth. The 80s had cold periods even when it didn't snow. Outside of 2015 it hasn't been cold recently. Ice is forming later (if at all) and melting sooner. Growing seasons are lengthening. Many places are exceeding 99th percentile frequency statistics for warmth parameters. While we can't know for sure how much our average weather has been affected by a changing climate, I'm personally convinced that it is now observable over our lifespans. 

6 minutes ago, EastonSN+ said:

Last year was due to (b) below, a deep west coast trough. A phenomenal year for California though as the reservoirs and snow pack increases were tremendous!

This year is due to (a) below. Another relatively high percentage warm setup for us.

2000 through 2018 we saw (c) ex. 13/14, 14/15 and (d) 02/03 a lot. We are in (and it makes me cringe) a 1970s through 1990s streak of winters which unfortunately happen a higher percentage of the time. 

The good news is we had good winters sprinkled in like 77/78, 93/94 and 95/96 in that 30 year period. In the last 5 years we had 21/22 as a really good winter sprinkled in. 

 

 

Those bins are a little too general IMO. Some periods straddle the boundary and in any given season we go through phases of each state. Regardless, they are not causing our weather, they are reflections of it.

What is likely as our climate continues to warm is that we will increasingly observe atmospheric circulation patterns in "warm phases." We will likely incorrectly attribute these warm phases to other geophysical parameters such as el nino etc. But in reality, what is more likely is that both el nino and other warm state indices are both correlated to a warmer base climate state as opposed to one physically causing the other. This is classic causal fallacy and it is common in amongst hobbyist meteorologists.

5 hours ago, wdrag said:

Not threading anything for the 27th-29th.  Ensembles offer NYC subforum around 1" of rain, give or take. River rises occur but generally within bank, except those that went to major a few days ago...those would rise back to minor flooding IF that rainfall occurs.  Think it best to wait this out. 

Brutal for ski areas. I'm still holding out hope for the Jan. 1-3 period. It's just far enough out into the fuzzy period of modeling that if we squint we can imagine a snow treat. 

6 minutes ago, EastonSN+ said:

For those who want to see how a vortex off the west Coast can and has (now and in the past) flood Canada with PAC air, run the loop of the latest EPS.

In the image below, see that deep blue, that spin is rapidly pushing warm PAC air into Canada (like a river from SW to NE). A problem with stronger El ninos. 

https://www.tropicaltidbits.com/analysis/models/?model=eps&region=nhem&pkg=z500a

 

But it also happened last winter. 

37 minutes ago, the_other_guy said:

List the ones that were bad. We did this already.

 

You got your Nino reset. Lets hope it plays out like you want. Id like to see AN snow.

The binarily defined parameters el nino and la nina are drastically too simplistic to explain continental-scale weather patterns by themselves. There are literally dozens of confounding variables, some already identified, some not. And in truth, the state of the coupled atmosphere and ocean system at any given moment is unique. It has never been before and never will again be in exactly this state. Efforts to characterize and lump together numerical indices to understand and predict these systems cannot fully capture their uniqueness and variability.

To base a forecast months into the future based on what happened decades ago during an "el nino" is laughably simplistic. 

57 minutes ago, Sey-Mour Snow said:

It's all semantics at this point, it seems like you agree with what we are saying, but are arguing otherwise.  Long story short, long wave patterns are generally forecastable 8-12 days in advance by ensembles.  Whether or not it produces the exact result we want or suspect is a different story.. 

I think I mostly agree, but with caveats. If you go back 10 days and compare the ensemble forecasted 10-day 500mb chart to, say, last night's 6hr GFS 500mb chart (or the actual 500mb interpolated analysis) you'll see some of the features match up well and others not so well. Whether or not we can say a model correctly forecasted a "pattern" is completely subjective and dependent on the spatial scale in question, criteria for defining a "pattern," and reference thresholds for accuracy.

People living in regions where the ensemble 10-day 500mb heights were poorly forecast would disagree that a model nailed a "pattern." In these areas, the airmass and surface features are drastically different than predicted 10-days ago. Since we never know for sure in advance which areas will be more accurately modeled and which less, it's very difficult to have confidence in even general "pattern" features at this range. What I have observed for many years on this forums is that posters (including meteorologists) confidently proclaim a particular "pattern" coming 10-15 days or more in advance but the realization rate of those prediction is much less than would be warranted based on the confidence in the original claim.

People instinctively clamor for understanding and predictability. There is desperation to see the light at the end of the tunnel. We cling to a simplistic understanding of the relationships between climate and regional weather. But we're collectively just not (yet) as good at seeing into the future as we think we are. And we rationalize it away instead of using honest assessment to understand our limitations.

2 hours ago, North and West said:

I always say something this to my dad when he mentions that the iPhone weather app or TWC app has snow or ice more than five days out.

Basically, we can detect temperature patterns, as in it is likely enough to support snow at that timeframe, but there’s no way to know for sure precipitation other than there’s a broad signal but no specifics.


.

Totally agree about the weather apps. 

In terms of forecasting temperatures 40 days out. In general it's basically a coin flip whether a particular day will be warmer or colder than "average." Average is of course a moving target. In recent years I would always hedge warmer than average for future forecasts. So maybe 60-40 warmer than average bet. A "snow supporting column" might be slightly easier to forecast in advance than surface temperatures, but at 40 days out it's essentially impossible to accurately predict.

2 hours ago, BoulderWX said:

If you want any real chances of a snowstorm before February all bets point to the Rockies. Anything on the east coast including NE will be a thread the needle through timing situation. I think we have a few chances in February but I will go on record as saying I don’t see enough of a pattern shift to produce any meaningful snow along the east coast, particularly the 95 corridor until the last week of January into February. 
 

would love to be wrong and wilL admit if I am, but not seeing anything that gets me excited about a colD and snowy January 

Do you really have confidence that we can predict February weather 5+ weeks in advance. Other than February being further away from a snowless period, I see no compelling reason to think January couldn't be better than February.

1 hour ago, Sey-Mour Snow said:

It's actually pretty easy to predict a general 500mb pattern 8-12 days in advance most of the time.. The 12-15 is a bit more suspect but we do nail that well in advance sometimes.. The pattern that will lock into place mid next week for 7+ days was well forecast by ensembles starting at day 13-15 last week... Just because it doesn't snow doesn't mean that the forecasted 500mb pattern was wrong, sometimes we just get unlucky.  In fact many torches are sniffed out well in advance usually by ensembles.. 

IMO you are a little loose with your terminology. People get so used to certain phrases that they start taking them for granted. Terms like "nail" and "lock into place" are subjective. The parameters and spatial scale in question as well as your criteria for assessing model accuracy are not clear. Even the term "pattern" is only vaguely defined. It's easy to rationalize having a good handle on something if details and definitions are kept fuzzy.

The magnitude and orientation of 500mb height values at the continental scale are modestly predictable out to about 10 days. But the point I've been trying to make is that regional weather forecasting at and beyond this time frame requires model accuracy that exceeds the current average error. Even if longwave trofs and ridges are roughly predictable, local sensible weather is highly dependent on fine-scale features and evolution that is outside the scope of model skill and only modestly correlated to large-scale features. It's hard enough to see a regional cold snap coming 10 days out. To detect a snowstorm at that range is really hard. And while everybody is looking far into the future for the perfect pattern, a decaying lake effect streamer could drop an inch or two almost without warning.

6 minutes ago, brooklynwx99 said:

they usually get the general idea correct, but the nuances can certainly get smoothed out. skill really increases inside day 7. it’s more about picking out different regimes at the week 1-2 range. for example, we’re going from a overwhelming Pacific trough to a AK ridge and +PNA

Let's get it solidly inside 7 days before we celebrate. LR ensembles hedge towards climo at the extended ranges. And we've seen hints of this kind of change already this year that did not materialize.

4 minutes ago, brooklynwx99 said:

i don’t disagree with what you’re saying, but if you’re trying to see what’ll happen more than a week out, there will inevitably be smoothing. it’s more useful to view them as “is this potential pattern more or less favorable than average for snowfall?” there’s no way to look at discrete evolutions there. it’s basically a game of probability 

it’s not like I enjoy looking at the day 8-15 range. i would like to track discrete threats, but that is nearly impossible at this range

That's fair. My preference is to just not look out past 10 days at all. But since I sometimes can't resist, I just assume that any model ensemble run out in that range is very very low accuracy. You seem to profess more certainty with LR forecasting than I think is warranted. That's really my only subtle disagreement. Maybe it's more enthusiasm than anything.

12 minutes ago, weatherpruf said:

There was a famous basketball coach who once said, give me a tall person and I'll make them a great player. One of the reasons I really dislike the game.

 I can't believe any coach would actually make that claim.

The average NBA basketball player is in the 99th+ percentile for human height. But the average very tall person is not great at basketball, and certainly nowhere near good enough to be an NBA player. If we plotted anomaly charts of nba basketball player's heights we would see that height is extremely well correlated to playing in the NBA. This is analogous to bluewave's favorite historical anomaly charts. Unfortunately in both cases, the underlying metrics are not very predictive of the thing we are trying to forecast because of rarity (northeast snowstorms and NBA skill) and poor correlation.

4 minutes ago, brooklynwx99 said:

there’s nothing misleading about it all as long as you know how to use the data. i would argue that a 6 hour snapshot can be even more misleading than a broad overview of the pattern

We clearly disagree then. LR ensembles are already averaged values, which significantly distorts magnitude and location of features, though still usefully out to day 10 or so. Additionally averaging across time scales modulates the resulting values to a degree that renders them almost useless IMO. This completely masks synoptic evolution of features, which is critical to regional forecasting. I believe that's a significant cause for so many head fakes and false alarms. Just look at the 5-day averaged anomaly charts for next weekend and compare that to the operational models. A post mortem of the past few forecasting seasons should shine some light on this issue. But based on what you've already written, I don't think we're going to agree on this point. I wonder who or what it would take for you to ease off the LR multi days averaged ensemble charts.

I don't think there is a more misleading model chart than a 5 day averaged 500mb anomaly chart. If I had a dime for every time Brooklynwx posted one of those and said how good it looked, I'd buy twitter.

15 minutes ago, bluewave said:

We were discussing a nearly 384 hr GFS OP very low skill hypothetical which changes every 6 hours to pass the time since people have been so bummed out about a lack of snow. Just read back a few pages to see the many challenges the actual pattern will have to produce snow. These continuing challenges through December were outlined here starting back in the late fall. So we were outlining changes which would probably need to happen in order for NYC to break its 1 and 2 inch record long losing streaks. 

My first post today was about next weekend i.e., about 180 hrs out. I pointed out that during this time period we briefly lose the western trof which you suggested was something we needed to get snow. 

My sense is that you are good at diagnosing the big picture. I prefer to look at the details, which I believe are critical for regional and particularly local snowfall. In truth I believe both scales are important. If the big picture is unfavorable, the details don't get you squat. 

16 minutes ago, bluewave said:

Then you haven’t been following this thread recently since the wave dynamics leading to these patterns have been spoken about repeatedly. 

Most people on this forum know that a pattern which produces snow is contingent on cold air. We know that the pattern I outlined which produces the benchmark storm track needs cold air for snow.

 

By the way, the reason why next weekend fails to deliver is not because of lack of cold. It's because the modeled PVA is either too far offshore of fails to fully round the base of the northern stream trof to initiate surface low formation close enough to our region to produce precipitation.

The difference between snow and no snow is in those fine-scale synoptic details and their evolution in time. Snapshot anomaly charts and "pattern" recognition just can't capture those details.

3 minutes ago, bluewave said:

Then you haven’t been following this thread recently since the wave dynamics leading to these patterns have been spoken about repeatedly. 

Most people on this forum know that a pattern which produces snow is contingent on cold air. We know that the pattern I outlined which produces the benchmark storm track needs cold air. 

 

 

I have been following intently, for years. I appreciate you enthusiasm a lot. I think your concept of "pattern" is on shaky ground. I also don't think the current state of LR forecasting allows you or anyone else to identify productive snow periods more than about 10 days in advance.

I would respectfully encourage you and everyone else to follow Walt's lead and focus more of specific synoptic feature combinations in the mid-range and less of fleeting fantasy "patterns" out in fantasy land.

6 minutes ago, bluewave said:

Complexity is just an excuse for the inability to see the greater underlying repeating patterns throughout nature which includes weather forecasting. 

I'll say it another way.

The physical and psychological attributes that make a good basketball player are complex. If we relied only on simplistic metrics like height to predict basketball prowess, we would not be very successful basketball scouts. 

The forecasting of complex patterns requires very precise identification of causal factors and large practice-set sample sizes, both of which are currently lacking in LR weather forecasting.

4 minutes ago, bluewave said:

Sometimes it is when the source regions are devoid of cold enough air as was the case on 12–05-20.

What you posted is not a "pattern." It's a graphical representation of a set of numerical values at the continental-scale. It's a purely static depiction. Any meaningful definition of weather "pattern" should incorporate the wave dynamics associated with evolution and propagation of airmasses. In that way, "pattern" and "cold" should always be interrelated.

In fairness, everyone on this forum would be better off if we all stopped using the term "pattern" because it usually just leads to misunderstandings and unfulfilled expectations.

6 minutes ago, snowman19 said:

The early January cool down is fitting the “script” of past strong/super Nino events to a tee. There is very good evidence (forcing) that come mid-late January we go RNA and it gets mild again. The big question is February. If this one continues as past events have, that will be the wintry month of the winter. Wait and see time now. So far the timeline is fitting perfectly ever since late November. 


See this: https://www.twitter.com/webberweather/status/1737967733260882329?s=46&t=NChJQK9_PUjA1K7D2SMojw

IMO the coupled global atmosphere and ocean systems are way too complex for easily identifiable and repeatable patterns. Personally I think there are general recurrent features, but not as predicable as you suggest. "El Nino" is a numerical range used to represent a particular geophysical variable in a general region. No two El Nino seasons are even close to being the same.