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December 2022 Obs/Disc


40/70 Benchmark
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12z GFS could happen....I'd bet against it, but it's just one possibility out of many. Probably 70-80% of the possibilities will be pretty good for us. But there will be a small minority where things go belly-up like on the 12z GFS where it retros the NAO block almost into the arctic ocean and prolongs the SE ridging....but again, that is a weird deterministic solution 10+ days out so you'd bet against it.

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7 minutes ago, brooklynwx99 said:

here is the run-to-run change from the 06z to 12z GFS OP. OP models always struggle at range, but they're going to struggle even more with a blocked up pattern with tons of amplification 

gotta use the ensembles, and they still look good

gfs-deterministic-nhemi-z500_dprog-1084000.thumb.png.33fef3394e07b4a7e932fb5c95506716.png

That's pretty cool.

I have no worries about the upcoming blocking.

If I had a "worry", it would be the duration of said blocking. It's less of a worry though and more of a question.

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Just now, ORH_wxman said:

12z GFS could happen....I'd bet against it, but it's just one possibility out of many. Probably 70-80% of the possibilities will be pretty good for us. But there will be a small minority where things go belly-up like on the 12z GFS where it retros the NAO block almost into the arctic ocean and prolongs the SE ridging....but again, that is a weird deterministic solution 10+ days out so you'd bet against it.

Yep, it's not a 0% chance, but you'd bet against it as you said.

 

Just like RIC getting 20" is a chance, but you'd bet against it.

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2 minutes ago, CoastalWx said:

Yep, it's not a 0% chance, but you'd bet against it as you said.

 

Just like RIC getting 20" is a chance, but you'd bet against it.

also, betting on something like that happening as opposed to the 06z GFS solution is like praying for a 2014-15 type pattern when the pattern is primed for a +EPO

here, the pattern progression most likely leads to a strong -NAO and trough in the east. other solutions are possible, but something like the 00z EPS is probably the most favored

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16 minutes ago, ORH_wxman said:

12z GFS could happen....I'd bet against it, but it's just one possibility out of many. Probably 70-80% of the possibilities will be pretty good for us. But there will be a small minority where things go belly-up like on the 12z GFS where it retros the NAO block almost into the arctic ocean and prolongs the SE ridging....but again, that is a weird deterministic solution 10+ days out so you'd bet against it.

I wouldn't give it much thought unless ensemble consensus begins consistently flagging that potential.

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14 minutes ago, brooklynwx99 said:

also, betting on something like that happening as opposed to the 06z GFS solution is like praying for a 2014-15 type pattern when the pattern is primed for a +EPO

here, the pattern progression most likely leads to a strong -NAO and trough in the east. other solutions are possible, but something like the 00z EPS is probably the most favored

I would also note that deterministic model guidance tends to perform quite poorly in high-magnitude blocking regimes...particularly during La Nina when storm threats are northern-stream dominant. But even just general longwave pattern verification tends to be worse in extreme blocking situations as per the literature on NWP guidance.

I gave a presentation on this at the 2011 AMEX conference as it pertained specifically to east coast storms. The models were having a really hard time "seeing" storms more than a few days out. It was a decade ago, but same logic would apply. Models are better now, but their relative skill declines in these high latitude blocking setups. During that 2010-2011 winter. almost all the big storms we got hit by weren't well-modeled more than about 3-4 days out. The best one was probably the 1/12/11 event which was pretty consistent on guidance form 5-6 days out. But I recall plenty of storms that season where they were on model guidance 7-8 days out and then disappeared by 4-5 days out never to return, and then vice-versa....nothing at all and then they would show start showing up 4 days out. Boxing day was kind of a weird one in that it disappeared 3 days out only to return 24 hours out.

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Just now, CoastalWx said:

So the GEFS right now as of hr 282 do not show what the GFS op showed. FYI.  Again, not saying there is 0%...but as Will, BrooklynWx have pointed out...you will see highly variable run to run solutions in the op runs. 

I'd say the same thing if they showed a Blizz of '78 redux...the odds of deterministic OP runs nailing the evolution of that block are pretty remote...just stick with ensembles.

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53 minutes ago, greenmtnwx said:

I think it’s fair to point out that things may not progress like we hope. There are signs that although we will get a block in Canada, it could be fairly transient and the ridge in east or at least zonal type flow resumes shortly after. There is a window but it may not be great. 

Given that the MJO is dying in phase 8 and we have a decaying la nina pretty heavily biased to the east right now, the default forcing will want to shift near the dateline. I find it hard to believe that this pattern doesn't reload following any relaxations later this month.

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1 minute ago, Baroclinic Zone said:

Can't post about op runs when they don't show cold/snow.  The all cold and snow crew will tear you up.

Post whatever you want. But understand why posting them is a not an accurate way to gauge the likely outcome. Like Ray said, same goes if it showed a 78 redux.

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1 minute ago, ORH_wxman said:

They will be quite a bit more accurate than operational runs though out in that time range.

Certainly no argument with that. 

But I think these past few years there has been way too much emphasis placed on face-value output of the ensembles without taking a step back to fully assess. I mean how many times over the past few years has the medium-range pattern looked great only for the complete opposite to happen at verification time? 

IMO, when you have these Nina conditions where the global pattern really is quite chaotic with so many moving pieces and so many ridge/trough patterns globally, sure the ensembles will probably pick-up what the pattern will average out too, however, it's going to fail at picking out the short-term variations within those patterns. I think this is why we've seen medium range guidance look great for snow events, but once that time comes its a crappy event b/c the way the pattern is evolving around the storm development its complete crap. 

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1 minute ago, 40/70 Benchmark said:

This is all backed by the tropics, though....not sure what last season has to do with it.

Moreso we've just been in a similar atmospheric state the past few winters (speaking ENSO here). Certainly other teleconnections may not be similar but we've been stuck in some sort of rotten regime the past few years (well several). 

We need to get rid of La Nina and give it a good year for the atmosphere to flush it's puke out of the system.

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11 minutes ago, weatherwiz said:

Certainly no argument with that. 

But I think these past few years there has been way too much emphasis placed on face-value output of the ensembles without taking a step back to fully assess. I mean how many times over the past few years has the medium-range pattern looked great only for the complete opposite to happen at verification time? 

IMO, when you have these Nina conditions where the global pattern really is quite chaotic with so many moving pieces and so many ridge/trough patterns globally, sure the ensembles will probably pick-up what the pattern will average out too, however, it's going to fail at picking out the short-term variations within those patterns. I think this is why we've seen medium range guidance look great for snow events, but once that time comes its a crappy event b/c the way the pattern is evolving around the storm development its complete crap. 

When it comes to ensembles, I usually look for a few things to be more confident:

1. Consistency.....are the runs more or less showing the same thing for several cycles in a row?

2. Timeline gets closer....is the pattern on the ensembles getting closer or staying out in clown range? Typically you want to see the pattern starting to get established inside of 10 days

3. Cross-guidance ensemble support. Are the EPS and GEFS agreeing with each other or are they showing different patterns? When you have multiple ensembles suites showing the same pattern, that increases confidence.

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10 minutes ago, weatherwiz said:

Moreso we've just been in a similar atmospheric state the past few winters (speaking ENSO here). Certainly other teleconnections may not be similar but we've been stuck in some sort of rotten regime the past few years (well several). 

We need to get rid of La Nina and give it a good year for the atmosphere to flush it's puke out of the system.

More to it than ENSO....this year has more in favor of blocking.

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