psuhoffman

Before we get too upset over whatever the gfs says what it now says 48 hours. 975 near Montreal. Look what it showed when that was as far out as the storm we’re tracking is. 986 off Maine. Meanwhile look at the euro from that range. Pretty close…

It was better than 18z but that run was awful... it started out pretty good, better than 12z even...talking about h5, but then after starting out more amplified and further west the upper low deamplified and flattened out again instead of digging and cutting off. Good start then crapped the bed.

How bout them cowboys

The way it gets there is more shocking...its not in the GFS camp its in its own universe with about as different an h5 progression as I've seen at this range in a long time on a major system. It does give us a coating of snow with the arctic front as the TPV passes across to our north but thats all it is...the southern feature slides off WAY to our south and that is because the TPV never splits the lobe off, it just elongates but remains attached to the Atlantic Vortex, it does that SW stretch of the trough thing we HATE with the tail and all to put it in the vernacular. Look at this crazy difference Euro AI Any storm is dead in the water with the AI progression LONG before it gets to the east coast...that is not even close to the setup advertised across the rest of guidance. The two camps are not all that different up until about 100 hours, then they diverge sharply and radically with most guidance splitting the TPV with the main Atlantic Vortex heading off northeast and the western lobe cutting off and diving into the Ohio Valley. The AI keeps the TPV intact as one shred factory to our north with absolutely no chance for anything to amplify as it drops in over us like a hammer. It's not even close to a storm...if all guidance looked like this I wouldn't be saying wait for the next run, it would be game over no hope that look is not even anywhere near a storm threat. That's what's crazy, its so far away from a storm its hard to believe that either of these solutions can be this far off...because one of them is going to be so horribly embarrassingly wrong here. I know the AI has some impressive early results but I've followed this new Euro since its last upgrade enough to know I would be shocked if it was this far off at this range. I am not saying it might not be over amplified, we've seen that...but this is more then that this is making a total mess of a really major hemispheric scale h5 feature. I'll roll with the preponderance of evidence that the Euro Op and EPS along with UKMET and GGEM and their corresponding ensemble systems are closer to correct here than the AI. Even the GFS isn't close to this extreme, its just a much less amplified version of the other camp.

I dug deeper into the 18z EPS... they were better than I originally thought Going back to my original breakdown... I looked at the individual members again at the end of the run 1) There are 20 members out of 50 where significant precip is definitely still going on after the end of the run. This would definitely add totals to the mean. 2) There are 5 members that I originally counted as weak miss nonstorms...but in reality they are slow. They stall the southern wave out and then phase late and as the run ends the storm is just getting going to our south heading north and likely to impact us to some degree. A few look ready to crush us and 2 look to at least get decent snow to us. So we are adding 3 from the weak/miss category to the jack and 2 are at least gonna be close that looked like nothing. After this I think the 18z is probably close to 12z its just got some members that are slower for some reason. There is more spread but its more about timing than track.

Looks like less spread to me. And keep in mind thats a 10-1 mean on low resolution members. Have to consider that when comparing op to ensembles. This is going to be a very cold storm...ratios will be higher than 10-1, especially up here.

Widespread 18”+

Take this FWIW but I just looks at every eps member and the breakdown of NW v DC area Jack v weak/SE members is almost exactly the same 12z to 18z. The difference is the weak SE misses went from close misses with a ton of snow just to our east to in many cases no stole at all with like 2-4” as the max anywhere. The weak camp got really weak. The already east camp went way east. The jack camp also lost some of its crazy 20-30” members. They are more commonly 8-15” type storms. Btw when judging the eps remember it’s a cold storm and they are low resolution using 10-1 and cut off the end of the storm. So a .7 qpf run is probably a 10” snowstorm. Comparing eps members to the op is difficult in that way. What to make of this? I dunno. It’s good the track among the majority camp didn’t shift much. But it’s not good the weaker solutions didn’t converge at all and went the other way. Spread increased some.

Looking at h7rh it’s still snowing from a Leesburg to DC northeast line and it’s not making much progress due to the inverted trough between the surface low and the upper low, it’s wrapping around. Probably can tack on another 1-3” across MD. Maybe more for us.

Ok a few points rattling through my brain 1) there are actually things I like better about this Euro run. It focuses on the arctic boundary wave associated with the TPV more (as I suspected and hoped guidance would come around to) and because of that it develops the system and starts to mature sooner. It moves a little quicker which cuts down snow totals from HECS to MECS levels. But its a much safer way to go, this progression would have a lot less bust potential than relying on the late bomb phase capture tuck scenario of the 12z euro where everything gets under us and we need it to come straight north really to get us...a SW to NE trajectory is much safer if we want to guard against a really bad GFS like outcome which honestly is more important to me than shooting for the moon here. Yea I would LOVE 20" but if it comes with a big risk of 2-4" instead...I'd rather take a safe 10-15" snowstorm. 2) The 12z op euro was one of the snowiest solutions across the EPS. There was one absolutely bonkers run that was a 2016 1996 type redux with 30"+ across the whole area...then there were 4 members that were similar...but the op was an extreme outlier high end solution. It was probably just random chance that it spit out one of the bigger permutations. A 8-15" type snow was the more common result across members. And then there were some "blah" minority results also...BTW among those there were more misses due to over amplified cutters than OTS GFS solutions, but there were a few of those too. All that to say, the 20" HECS solution was never the most likely outcome even within the euro suite. 3) anyone who throws a fit if we end up with a 10-15" snowstorm should be taken out back the woodshed and *&^&%*$&&*%&%. Frankly that goes for a 8-12" storm also... if we end up with some 4" weak sauce ordinary storm sure, if MD gets fringed again sure...if this euro ends up the final result we should be acting like those people in philly after the eagles won the super bowl. We haven't had a widespread storm like that in years. We don't live in Vermont. A 10" snowstorm is a freaking huge win. 4) The DC-Baltimore area has had 10 HECS storms since 1950 total...and worse only 1 of them came in a la nina winter. 1. 1 more than none. in 75 years. So get that out of your heads. If we do get a HECS then act like you just won the weather lottery because you did. Frankly we've only even had 8 MECS (this is subjective but by my count) storms in the last 75 years in a la nina. But that's way better odds than 1. 8x the odds lol. So I think MECS is probably the reasonable high end expectations here and that should be totally fine. That's still a super rare outcome! When I said I think this happens and we have a good chance at a big snowstorm before the winter is over...I wasn't ever thinking HECS. I was picturing a 8-12" type storm.

Of nachos damnit

I’m out

lol I’m not a head in the sand kinda guy. Give us all the evidence and I’d some can’t handle the truth…that’s on them. Anyone who’s been in this game more than 2 seconds is used to the up and downs. Mostly downs. But that’s not that bad. Yea it’s a step back but not a disaster. To me they looks like it must have increased spread. Larger area of snow, duel maxes, no big max Probably divergent camps. I’m less familiar with uk ens tendencies though since I’ve never had access to them.

Question to those who may know. Years ago the GFS suddenly popped a crazy storm at like 120 hours that no other model had. NCEP said it ingested some faulty data that caused it and they disregarded it. The next run backed of a little but still had the storm and some were arguing it wasn’t the bad day then, but someone familiar with the NWP said it would take the GFS several runs to flush the effects completely since it has some continuity between runs. I think it had to do with using some data for initialization from the previous run. Is this still true? If the GFS was off on a tangent due to some miscalculation can it take multiple runs to correct itself due to continuity between runs?

To be fair no model usually wins when it’s totally on its own. But the euro does sometimes. It just did yesterday. For one day it was totally by itself saying “nope” to any front end snow with the wave yesterday while the gfs/ggem/NAM all had 1-3” up here. Euro won. They all caved. But that’s kinda rare and I can’t remember any cases like that when the ggem or gfs were completely alone and won. Famoulsly it was showing a HECS for days around hours 100-150 in Feb 2021 but was all by itself. And some even said “it has to mean something that it’s so consistent”. Yea it was consistently wrong.

@Terpeastany good analogs showing up today?

@mitchnick did we ever get a UK ensembles update?

A Euro UK Ggem trifecta is a hill I’m willing to die on. If we have to be missing one of the 4 major global the GFS is the one I’m least upset about. I can’t remember the last time it was off on its own like this and won.

I’m not sure how resolution affects a non physics based model. But it’s been jumpy. And it’s tended to be under amplified. We leaned on it a few times this year and it let us down. It was under amplified some this week with the New England storm also.

I find it a little hard to believe a system amplified enough to put down 12-18” in Missouri is going to wash out that much given how much space there is between the detached TPV lobe and the departing vortex. The flow doesn’t look that suppressive. Thinking back to a similar wave in Jan 2021 that got squashed that way, the flow was a shred factory then compared to this.

That's a firm declaration, coming from you

Sounds about right...and probably a reasonable "max" potential for that location.

It was a good trip, but unlike Bif, all I came back with was a damn weather almanac

That was almost 100 years ago and measured at the Arboretum I think... not a runway on an island in the patomac river. lol They probably won't ever challenge that so long as they keep the official records at DCA.

The most similar evolution in some ways was Jan 96. But that cut off and dug way further south...but initially they are similar in terms of how the NS is situated, where its digging in, and where and how amplified the STJ wave ahead of it is. Then they diverge in that the 96 storm the H5 dove all the way into KY, this one comes across closer to our latitude. That might limit this storms ability to get cranking as far south as 96 did...although we don't really need that since the heavy snow extended really far south in VA in that one.