December 19-20 Talking Points - Part 3

[Isotherm]

PV slightly NW of its 12z position.

[PhineasC]

I'm thinking the Euro was a bit too extreme today..18z nam went the opposite way and it looks like the 18z gfs is trending less amplified than 12z, also the opposite way. very interesting.

I don't think the 18Z runs are allowed to call the Euro wrong...

[tombo82685]

hr 75 graze with lgt precip on the coast

[PhineasC]

For the millionth time, it has been shown that for years now the 06Z/18Z runs are just as accurate as 12Z and 00Z runs.

There is a discussion ongoing about data ingest that might make that untrue in this case.

[Colin]

I don't think the 18Z runs are allowed to call the Euro wrong...

no, not at all..just would have liked to see at least a trend toward the euro on the 18z runs.

[Stormlover74]

I concur.

When we are awaiting models can we ask that no comments be made about models unless its a Met, John or Tombo? Especially when there is a possible storm

I think everyone would enjoy that.

Rossi

[Joe4alb]

it is also interesting to note that many of the other models are showing pretty intense development at 84hrs+ , but the NAM still has two lows..

[famartin]

i believe that is against protocol if I remember correctly. When I was forecasting in SUNY Albany 40% 3 days out was considered a max.

I don't recall of any such protocol for how high pops can be at a certain time frame.

[joey]

http://www.meteo.psu.edu/~gadomski/AVN_18z/avn72.html

GRAZE

[earthlight]

I certainly am not crying that these runs are less amplified given the euro and it ensembles...but I def. was hoping they would at least nudge west.

[A-L-E-X]

that has to be one of the top weenie phrases i love the fact that people tell themselves that to make themselves feel better or have more hope...it's not true at all.

although you can say the SW's onshore sampling data hasnt been incorporated yet, so the 0z is likely to have much better info than either of these 18z runs (NAM or GFS.)

[LocoAko]

There is a discussion ongoing about data ingest that might make that untrue in this case.

Oh, about the Euro getting the new 12Z radiosonde data with the shortwave in it but not the GFS and NAM? That may be entirely true. I was speaking more longterm. I forget where the graph is but it shows that the 5-day error is pretty much the same on all 4 runs of the models now, since the radiosondes make up such a small component of the input data (with satellites making up most of it). However, this may be one of those cases where the radiosonde data makes a world of difference...

[Joe4alb]

I don't recall of any such protocol for how high pops can be at a certain time frame.

Let me refrain from using the word Protocol. More of a guideline when issuing forecasts to the general public. But it is written in one of the 10,000 books we had to read. Just please don't ask me which one.

[joey]

Why is it stringing out the low?

[A-L-E-X]

I certainly am not crying that these runs are less amplified given the euro and it ensembles...but I def. was hoping they would at least nudge west.

And ya know, I know people are saying that the 6z and 18z of the GFS are just as accurate as the 0z and 12z but I distinctly remember seeing a verification score graphic a couple of years ago showing otherwise.

[blazess556]

I'll ride the euro and its ensembles into the sunset.

[A-L-E-X]

I'll ride the euro and its ensembles into the sunset.

0z runs are ultra important, especially with that new data coming in.  Might be a sleepless night for some lol.

[Zelocita Weather]

Why is it stringing out the low?

Looks like it is also trying to key on a temp difference/focal point of low formation well SE (almost on the 10C line)...and it is not focusing on 1 main point where the low will be.

[nzucker]

I'll ride the euro and its ensembles into the sunset.

I still think this storm's going east and going to miss us. Very poor trends on the 18z GFS and NAM; I feel that the southern stream shortwave is going to run out too far ahead of the more potent northern stream in the zonal flow off the Pacific, and that the system won't get pulled back towards the coast in time.

[earthlight]

The shortwave argument is legit..but I think if you want to back up the Euro you can just say it uses 4DVAR and has a resolution way higher than the GFS.

[earthlight]

The 4DVAR initialization scheme and higher resolution should arguably give it's solution more weight especially with it's bumps west and the ensemble agreement.

That being said, there's still so much time left to go in a pattern this fragile. My confidence is very low and would be even if every single model showed a blizzard.

[XtremeWx]

What time does the 0z run come out?

NAM comes out at 8:45pm

GFS comes out at 10:30

Euro comes out at around 12:50am

[A-L-E-X]

I still think this storm's going east and going to miss us. Very poor trends on the 18z GFS and NAM; I feel that the southern stream shortwave is going to run out too far ahead of the more potent northern stream in the zonal flow off the Pacific, and that the system won't get pulled back towards the coast in time.

Lol I cant believe youre serious about going by 18z modeling information.  The fact is the GFS and NAM are both inferior to the products put out in Europe.  I just wish we used the 4DVAR data assimilation scheme.

[LocoAko]

And ya know, I know people are saying that the 6z and 18z of the GFS are just as accurate as the 0z and 12z but I distinctly remember seeing a verification score graphic a couple of years ago showing otherwise.

Not saying this is the case for this situation, as other factors may be at play. But here.

http://www.americanw...merical-models/

[goombatommy]

NAM comes out at 8:45pm

GFS comes out at 10:30

Euro comes out at around 12:50am

Thank you Xtreme.

And seriously, why are all my posts being removed? It was a legitimate question which searching for yielded no results.

[IsentropicLift]

someone stated on the main thread that the GFS looks to be suffering from convective feedback with its eratic re-development of the system....and it does seem to be worth noting

[jm1220]

Looks like convective feedback issues on the GFS this run? There's a mysterious blob of convection SE of the low and a vort that might be robbing our storm on this run.

In any case, I haven't really lost any enthusiasm since seeing the Euro today. 0z tonight and 12z tomorrow will be very crucial. If the models hang on for 12z tomorrow we should be pretty much a lock for a substantial storm. If they begin to fall east again tonight and tomorrow, it's almost certainly over as all the relevant data will be sampled by then. The Euro must have noticed something to make it and its ensembles into that crazy solution today (after starting to trend last night), since it was flat as a pancake for numerous runs prior. It's probably unlikely it becomes that deep, but a storm like this has to be watched very carefully because of the chance for a stall due to the blocked up pattern. It also won't take much at all in terms of energy to spin a storm up here. The Polar vortex is in a favorable position and backing away as the storm approaches. It's really all on the southern stream.

I also remember distinctly the NAM and GFS playing these convective feedback games before the 12/19 storm last year.

[SACRUS]

Thank you Xtreme.

And seriously, why are all my posts being removed? It was a legitimate question which searching for yielded no results.

GGEM 1130

UKMET 1130ish

[A-L-E-X]

Not saying this is the case for this situation, as other factors may be at play. But here.

http://www.americanw...merical-models/

Your data definitely trumps my memory Jake, although the graphic I saw on eastern was way back in 2006 or so lol.

[Rainshadow]

The 12z run today brought the southern stream short wave to the Conus, the 12z run tomorrow will for sure have the northern stream short wave, that should be the definitive run. While I would find it hard to believe it would not snow after all is said and done, there is a modeling and ensemble split between phasing and not phasing this system.