December 2023

[IrishRob17]

2 minutes ago, North and West said:

I have been watching TWC my whole life and my closest, lifelong friends are meteorologists… and I’ve never heard them mention that before.


.

Then why are you always asking for people to explain it to you like your five years old?

[North and West]

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. 

That’s a good point. I just sat down and opened up the app on my phone, and it told me I hadn’t checked in eight hours (this is my go-to social media this time of year). Kind of bums you out when you realize it’s a few days before Christmas and it’s boring out.


.

[North and West]

Then why are you always asking for people to explain it to you like your five years old?

Because they’re a lot smarter than me, and I didn’t go into it as a career. Essentially, I want the abstract.

(Plus, it’s one of my favorite gifs!)


.

[eduggs]

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. 

[brooklynwx99]

the pattern change is becoming more potent and moving forward in time. look at the ridge into W Canada and AK. i don’t get some of the griping. it’s not a perfect pattern by any means, but the AK ridge will provide cold air, and there is a 50/50 signal with the low heights over the N ATL

[brooklynwx99]

i don’t see a can getting kicked at all. also, i wouldn’t call that a cutter pattern. there’s a trough in the SE, and the NW flow over central Canada would force surface HP

it’s a split flow pattern… seeing the STJ undercut the -EPO is cold and active. it’s not the same as a Niña black hole digging into Baja CA

[wdrag]

If is ok... will start Jan thread tomorrow morning 8A.  Long day here.

Always hope in the future... just not obvious to me about big snow, except it gets cooler first week Jan.

Walt

[eduggs]

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.

[North and West]

i don’t see a can getting kicked at all. also, i wouldn’t call that a cutter pattern. there’s a trough in the SE, and the NW flow over central Canada would force surface HP
it’s a split flow pattern… seeing the STJ undercut the -EPO is cold and active. it’s not the same as a Niña black hole digging into Baja CA

It’s better than what we’ve had, correct?


.

[brooklynwx99]

2 minutes ago, eduggs said:

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.

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

[weatherpruf]

1 hour ago, eduggs said:

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.

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.

[snowman19]

24 minutes ago, brooklynwx99 said:

the pattern change is becoming more potent and moving forward in time. look at the ridge into W Canada and AK. i don’t get some of the griping. it’s not a perfect pattern by any means, but the AK ridge will provide cold air, and there is a 50/50 signal with the low heights over the N ATL

Early January cools down, then we very likely go mild again, RNA, mid-late month given the forcing progression IMO. Do we get “something” early January? Your guess is as good as mine. I still think February probably produces as of right now 

[eduggs]

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.

[brooklynwx99]

5 minutes ago, eduggs said:

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 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. there’s nothing wrong with data, though. more data is powerful. not sure why this irks so many people

[eduggs]

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.

[brooklynwx99]

6 minutes ago, snowman19 said:

Early January cools down, then we very likely go mild again, RNA, mid-late month given the forcing progression IMO. Do we get “something” early January? Your guess is as good as mine. I still think February probably produces as of right now 

let’s get through the more favorable window before looking at the next relaxation. the pattern relaxes, but it also shouldn’t be as bad as December was

early Jan looks BN with split flow. we’ll see what occurs

[eduggs]

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.

[brooklynwx99]

5 minutes ago, eduggs said:

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.

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

[eduggs]

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.

[Dark Star]

1 hour ago, North and West said:

I have been watching TWC my whole life and my closest, lifelong friends are meteorologists… and I’ve never heard them mention that before.


.

I wouldn't say it is unimportant, but it could help you "visualize"  the relationship between pressure, heights and the role in interpreting "thickness" (I think).  I couldn't calculate a natural logarithm anymore (or even an unnatural one)...

[psv88]

24 already. Probably will drop into the teens tonight 

[Sey-Mour Snow]

43 minutes ago, eduggs said:

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.

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.. 

[NittanyWx]

For what it's worth, these models have no real E Canadian HP signal until very briefly around the 5th.  So if we were to get any storm ahead of that, regardless if it's a lake cutter or not, you'd have a big issue with cold air supply.

 

If you were to get some energy out of the southern stream around then while that high is retreating, there's a small potential window around than Jan 4-6.  As noted, however, I tend to think in regimes like this where h5 is favorable but source air is not, risk is HP/cold air associated with it gets overdone extended range.  

[justinj]

7 minutes ago, psv88 said:

24 already. Probably will drop into the teens tonight 

Gabreski airport currently 18. 23 currently in middle island 

[MJO812]

6 minutes ago, NittanyWx said:

For what it's worth, these models have no real E Canadian HP signal until very briefly around the 5th.  So if we were to get any storm ahead of that, regardless if it's a lake cutter or not, you'd have a big issue with cold air supply.

Yes this far out but you have to be excited ( yes I know it's far out ) how this pattern is evolving . Compare this time last year to this year. Way different.

 

[Stormlover74]

5 minutes ago, MJO812 said:

Yes this far out but you have to be excited ( yes I know it's far out ) how this pattern is evolving . Compare this time last year to this year. Way different.

 

I was excited for last March. I'll get excited when something shows up on the models and is still there 5 days later

[BoulderWX]

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 

[MJO812]

6 minutes ago, Stormlover74 said:

I was excited for last March. I'll get excited when something shows up on the models and is still there 5 days later

Yes I agree . I know people are cautious but they are really cautious compared to other subforums on here and other forums. 

I'm excited for the upcoming pattern ( yes I know it can change ) but we haven't see snow in a long time. 

[coastalplainsnowman]

 

2 hours ago, eduggs said:

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.

He posted one 440,000,000,000 times?  Crazy if true.

I think that people who have a nostalgic love of snow and follow things on this board as hobbyists (present company included) are practically guaranteed to be unhappy if they set unrealistic expectations.

- If you love snow, and you're a met, that's great because it's great to be enthusiastic about what you do for a living, or aspire to do for a living.

- If you are someone who loves snow, but doesn't know about this board, then ignorance is bliss.  If it's cold out, like it has been the last few days, you're loving it, not having much awareness about the fact that it will probably warm up and rain a little right on time for Christmas.  You're living in the present and enjoying the evening.  You're hopeful (and likely correct regardless of everything discussed here), that you'll get at least one or two grass-covering snows that will slow life down a bit this winter, and you look forward to it.

BUT, if you love snow, are not a met, and follow here to learn and to get the inside scoop, then you're rarely happy if you let yourself set your expectations too high.  Sure, it's been crisp and cold the last few days, but we're bummed because we know it'll be warm soon.  When it snows, we know with specificity when it's going to get washed or melted away, rather than being able to dream that winter wonderland will last for awhile.  And while it is actually snowing, we watch the radar instead of the actual snow - the thing we waited for for months -  aggravated that the very best bands aren't on top of us, and watching the western edge speeding eastbound from PA.  Or, we watch the rain/snow line inching closer, and make sure we spoil the fun of those around you by letting them know. 

 

 

 

[eduggs]

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.