ORH_wxman

PAC actually improved on the EPS out beyond the first 8 days and that east based NAO seems to be slowly getting stronger. Most notable step back today for me on the EPS was the weaker 2/20 system which produces less confluence behind it....keeping it more zonal for 2/22-23. IF we're gonna sneak that 2/22-23 system in as a winter event, we'll need the prior one to set the table.

I fully expect the Pacific to be crap during this entire period...and probably trend worse with time as we get closer....which is why all the other variables are important. We want that wave break to be as sharp as possible from the 2/20 system

I didn't like the trend of weakening that 2/20-21 deal in flatter flow....it doesn't drive the boundary down as far south behind it....you can see it on the EPS too with the heights in SE Canada not as low after that system as the 00z run. We want the flow a bit more amped for that one like GGEM/Ukie. But that's what the 2/22-23 system depends on. Doesn't really affect the systems that potentially may come after that (like 2/25-2/28 timeframe) But if we're gonna try and steal that 2/22-23 deal next week, then we need that front runner wave to be pretty amped.

That shortwave that ejected from the southwest (the one in TX at 168 and off Carolians coast at 192) whiffs us....prob why we got a bunch of weak unorganized crap this run.

Function of both the winter (lack of snow events) and the current pattern (nothing imminent inside of 7 days). Also a function of more model data and more model runs.

13

We could end up with a 1980s sensible wx solution if things break wrong....cutters followed by arctic shots.

Problem is people get married to a solution or set of solutions that are really good....like we've seen several GFS runs produce multiple warning events and now when we get one that doesn't, it is deemed a failure before it ever got inside of 7 days....it's extremely hard to talk in layman's terms about probabilistic forecasting. Any threat from like 10 days out prob has something like a 1 in 5 shot at ever verifying (or even worse odds depending on the pattern).....but a good pattern will produce like 4 or 5 "threats" in the pipeline, so odds are that 1 or 2 of them will be hits by the time you get it closer. That's sort of what this pattern is showing....there will be a few shots....they all won't hit. Hopefully 1 or 2 of them do....but it's still possible none of them hit. There is a distinct cutter risk still....I think we've talked about it several times, but for some reason people act like we didn't mention it when an OP run (like today's 12z GFS) shows a cutter....they go "SEE!!! I TOLD YOU!!!! Its the same pattern!!!!1111111!2#3!!!!"

Are people supposed to not discuss guidance? I don't understand the ridicule for people pointing out patterns shown 10+ days out....an overwhelming majority of these posts are not making a forecast or saying it will definitely happen. Most of them are caveated with "hopefully we can get this inside 10 days" or some iteration. The worst is people who actually say nothing will change with extreme confidence and zero probabilistic nature to it. Persistence typically fails in the most high-leverage moments....which is why using it is so bad. Take the cold shot for example....yeah, it wasn't a snowstorm, but that cold shot was met with a plethora of "add 20 degrees" or "add 30 degrees" or "it's a complete model fabrication" type posts from the usual suspects....even when it was like 6-7 days out. Well, they look enormously ignorant now.....when the forecast actually mattered in a high-leverage type of event.

Fwiw, GEFS much more Ukie/GGEM-esque in the handling...though not quite as steroidal as those two...they were pretty suppressed looking.

FWIW, there's a difference between OP GFS and both Ukie/GGEM in handling the TPV extension over Hudson Bay. Ukie/GGEM are similar whiel GFS was quite a bit weaker this run with the TPV extension pressing down.

Yeah there is a little front-runner wave there...GFS on a few runs had advisory type snows with it...Euro last night actually had like 1-3" south of the pike. But some models don't produce much of anything.

The same system on the GFS that cuts actually whiffs us south on GGEM.

Funny how ridiculous some of these runs are in the final week of Feb....like 3 different storms. Even though it prob won't verify, it's a good illustration of the way these patterns can be prolific if things break right....we've seen some of these gradient patterns in the past go nuts where you are getting a system every 2-3 days on that fast flow (think Dec 2007, 2008 or Jan/Feb '94 or even Feb/Mar 1967)

Right, I wasn't saying the blocking is due to the 50mb split, but it give it a good chance of sustaining more. I think the initial NAO action is caused by the wave-break around D6....then it gets reinforced a couple times, but in order for it to be sustained into March, that PV split would help.

Blocking is already retrograding some at the end of the EPS....still a ways out, but we're starting to see evidence that we might actually get a more sustained -NAO.

Putting away the snow blower in mid-February in southern New Hampshire…got nobody to blame but himself if he has to dig it back out to deal with a snowstorm.

Good overnight runs. But yeah…long ways to go. At least we’re seeing consistency.

18z EPS only goes out to 144. The front running wave is pretty amped though which is good for sending the boundary well south behind it.

Nothing ever looked this good inside of 10 days since December though. We had some runs that showed decent patterns but they usually fell apart before getting inside 10 days. We did have a couple runs show brief threats in early February but they ended up suppressed and we got a historic arctic outbreak instead with no real snow to show for it.

There’s also a lot of cross-guidance support and a lot of ensemble support within each model…and we know that matters too for forecast confidence. The only inhibiting factor right now is lead time. Inherently day 9 forecasts are going to be uncertain, but this is much better agreement than we’ve previously had on a day 9 look for something wintry…prob since December.

EPS also continues to trend stronger with the east-based -NAO in clown range. This is a good sign because that is what the weeklies were doing toward the end of February…and if you want a fun period for a few weeks, we want the weeklies to verify more or less. Note how in response to that, we see an intensifying minimum in heights over the 50/50 region.

As Tip and I were musing…good luck figuring out the dominant strain in this fast flow…buckshot look on the ensembles. But you do love the look of a scooter high to the north.

It’s a moot point at this time range but the entire system would slide south of SNE if euro went out another panel.

Yeah def not a single defined wave. It also has a 3rd wave in between those two for 2/22. It misses us that run but it shows how many different shortwaves could focus more significant cyclogenesis. We don’t know which one it will be. That one later on in the 23-24 timeframe looks the best but can’t rule out a two-wave idea either ala Feb 8-11, 1994 or Dec 19-21, 2008. Even Feb 7-9, 2015 I think had two distinct waves even though in the OES-zone the snow never really shut off…but elsewhere back in our exurbs neck of the woods in the 495 belt, it did.