psuhoffman

Fringed

As of now the eps favors the warmer solution. But it’s not a case where there may or may not be a storm. The storm is there just the eps favors too much ridging in front and torches the temps. But watch that change in a dime if a future run decides to phase the ocean storm next week with the NS and suddenly there is a 50/50. Or it suddenly decides the NS vort in Canada next week is going to bomb. So imo it’s one of these situations that looks bad and isn’t likely but could flip on a dime if just one thing breaks our way. Ironically the gfs and euro flipped positions in the last 48 hours. Wrt the eps there was a huge spike in snow just southwest day 15. Looking at the members there were several “incoming” storms at day 15. Day 16 was going to be big. Lol

That’s some of the most redonculous blocking I’ve ever seen. All of Canada. Why it still manages to snow with a primary way west. I’d settle for just getting the 50/50 and have the storm stay under us. I like simple.

Last post for a while...have to get back to work This is the issue with the progression...EPS day 10 The timing of the ensembles is a little slower than the op but this shows the issue. The flow ahead of the trough is all out of the south. That is torching the mid levels. If we had some cold to work with in the mid's we could probably overcome the warmer surface temps...mix some cold down with a good track...but if we torch the mids and the surface...well its game over. So taking the 6z GFS that had snow as an example This wasnt perfect...it was still messy, the ridge would be better centered west not east of the Hudson Bay, but that 50/50 makes it work. Look at the flow now over us and to our northeast. Cutting off the southerly flow from torching us ahead of the trough. Plus it creates confluence to hold a high pressure in longer. This lead to the snowy solution on this run. The op euro though... That same feature is displaced where it can't help us and so the southerly flow torches us ahead of the system and there is no confluence to our north. It's close...but this isn't horseshoes or hand grenades. So how can we get to the look we need.... So there the energy that will be the day 10 threat is coming onshore in the west. We need to get one of those vorts numbered to amplify significantly and into the 50/50 spot. What happens on the euro op, 1 amplifies but remains cut off from the NS flow so its too far south, 3 gets absorbed into the TPV lobe and up into Greenland...2 washes out completely and 4 does end up where we need it but doesn't amplify enough and is way too weak to do much good. Get 3 and 1 to phase and pull them up into the 50/50 domain and that works. Get 2 and 4 to phase and amplify...get 4 to amplify by itself. None of those solutions would do us any good for snow BEFORE the day 10 threat... the flow is way to suppressive, could help give northern New England a light event...but any of those combo's would knock down the ridge to our northeast, create confluence and shunt the southerly flow ahead of the wave from destroying our thermal profile. Hope that explains what you were asking. Back to real life...

BTW wrt to the EPS, while the snow mean is unimpressive, there is a big spike just to our southwest day 14-15. A lot of members end day 15 about to blast us with a stj system, this time with cold locked in thanks to the lower heights to our northeast due to the storm day 10-12.

Euro depiction of slightly above normal temps between day 7-12 is reasonable given its stale cold air trapped under a ridge. But we can snow in that profile...especially if we can fix the ridge issue to our northeast allowing the mid levels to torch ahead of the wave. It's cooling again day 15 either way. GFS is too cold in the long range...we know that.

This look here day 13 actually fits the profile of our “positive AO big snowstorms”. Obviously we want a -AO. But when we scored snow with a +AO it was often in a look like this... Whatever happens with the day 10 threat the eps thinks that system migrated through the 50/50 region knocking down the ridge to our northeast. The fate of the day 10 seems to rest on the ability of some discreet wave before that to amplify just enough to knock down heights there ahead of the day 10 storm. A murkier proposition in the spread.

Eps isn’t there yet but trending the right way. Remember the Hudson Bay ridge look I posted wrt the 50/50. This is the h5 run to run change leading into the day 10 threat. This is exactly the trend we need. Lower the heights to our northeast and this becomes a classic snow look. After that the eps opens the door that the day 10 storm becomes a 50/50 for a threat later. Lots of possibilities with the current pattern progs. GEPS looked good day 10-15 also.

That is about as good a 5 day mean that far out will ever look. We see higher ens means but it’s always either a close range threat or over a longer period that includes multiple threats.

Yea but with a primary unto Pittsburgh and a secondary near Annapolis it wouldn’t matter. But the exact track at day 10 doesn’t matter either. The ingredients we need are all there. We just need them to come togterget properly.

Here is how the look for around day 10-12 has shifted on the GEFS (EPS is similar). Now this time we are comparing a day 15 look to day 10..(last time it was day 10 to 7) so the shifts are going to be a bit more drastic...but still the large scale longwave pattern wasn't awful. GEFS from a few days ago This was a very cold look, big EPO ridge with cross polar flow directed right into the eastern US. But it's also a dry one, and I mentioned that a few days ago when this look was being tossed out. This was likely to be very cold but very dry. The other 2 major features were the PV situated across the NAO domain across the pole into the Kara region, eastern trough, trough in the Pac NE of Hawaii. This is how it has shifted So again it was too far west with the pac trough...this shift pressed the epo ridge into more of a Hudson Bay ridge. It was correct with its NAM depiction and the trough in the east. Now this has a positive and a negative. It cuts off the cross polar flow, so this is a much less cold look. But this is also much more likely to get something to amplify into the southeastern US. That blocking ridge across Canada will cut off arctic cold but there is a shot of cold into the east ahead of this...and so long as that is trapped under the block and not scoured out that usually is good enough in January. Ideally I would like a 50/50...that could end up being the big issue here if too much ridging in the northeast allows the system to cut... but this still has potential imo. This is a composite of 16 warning level snowfalls at BWI with a Hudson Bay centered ridge. The obvious thing missing is the 50/50 low. But that is a composite, not ALL 16 of those had a 50/50, but most hence the mean. But at this range a feature like that could be missed, perhaps an unseen vort next week, Ralphs clipper, can bomb out into the 50/50 space, or perhaps the day 11 storm does cut but becomes the 50/50 for the day 14 threat. Either way, this look is way closer to a big snow look than the one a few days ago. It's not nearly as cold...and it could end up a rain look also...but you have to play with fire to have a nice BBQ! If you did want a week of frigid cold dry weather...I apologize, things are not moving in the right direction for that.

@Ji @Ralph Wiggum Was going to post this earlier this morning then got distracted with work. But this is an example of how the overall long range guidance was right...but discreet features within the longwave pattern that are not discernible at long range will determine snow/no. For next week...the period Monday to Thursday...from long range it looked promising Ridge bridge across the top, western ridge, eastern trough...this look could definitely work The overall longwave pattern was pretty close but some details have shifted this to an unfavorable (for us) look Still have the ridge bridge over the top and eastern trough but the system crashing into the Pac NW is shifting the western ridge too far east and that shifts the eastern trough too far southeast...this is now a good look for a possible snow for places in the southeast, maybe the outer banks. Doesn't mean they get snow...but they have a chance which is super rare in itself. The slight error on a specific feature that will not be resolved at day 10-15 shifted this from a very good look for snow to a cold/dry one for us. The guidance wasn't wrong or bad...we just can't see the details that will determine our fate wrt snow from that range. Only the general longwave pattern. Even in a good pattern we need luck with the discreet features. Only a relatively narrow area will actually get snow in any given (short) time period. The coverage of snow with a storm isnt that large typically. Or the difference between a wave amplifying or getting squashed isnt that big on a hemispheric pattern scale. Too many people assume if we get the good pattern it means we get snow. Not the case.

There is "slightly" too much ridging to the northeast, the h5 trough amplifies slightly too far west, the airmass is slightly too warm... a lot of very small imperfections combine to ruin it on this specific op run, but like I said yesterday this setup continues to be a "Ohio cow's fart in the right direction" from being a big snowstorm for us. There have been plenty of similar situations where at LONG leads the guidance thought what ended up a big snowstorm was a cold rain event. I will take my chances on this setup. It's the best one we have had yet this winter.

Wernt the Models recently showing a big nao in the 6-10 day window? Briefly and it’s still there next week but it’s a wasted window (probably) because the trough axis is too Far East. Was about to post on that. Looks like a great chance for the southeast coast though.

What is frustrating is we keep cycling between the PAC and ATL taking turns crapping on us. The pac looks to get pretty good for the next 2 weeks but the scandanavian ridge suddenly flips to a trough which allows more ridging to shift across into a position that could muck things up. It's still not a bad look...but "one thing" keeps going wrong. The thing is..that is normal. Because to get snow we need so many more things to go right than wrong...that more often than not one thing will muck it up. Kinda like a golf swing.

Before I start a weenie stampede I should clarify that this setup does not have the upside those other storms I referenced did. I was purely using the airmass similarities. Without Atlantic blocking this storm would be more progressive. If it rides the coast it would likely blast up the coast not stall and dump on the mid Atlantic. But those can still be very good snowstorms. Just usually not 2 foot HECS ones. And it would have a higher chance of cutting. And if it did stale cold won’t work. I was simply saying if we get a 990 low up the coast with a perfect track I do not buy the rain scenario.

I will say this...if we do get a miller a storm with a perfect track (barring bad luck with a NS vort like the HH gfs run) I don’t buy the rain idea. I said the same thing when the Jan 2016 storm first showed up around day 12 and was warm on guidance. Euro was showing a perfect track gulf low rain storm when it first came into day 10 range. And I said BS. If it goes down like that in January stale cold will be good enough. Feb 5 2010 also was warm at really long range. Same reason. Same result. History/climo says stale cold stuck under a Canadian ridge is good enough with a good storm track in January and February. Climo for an advertised pattern beats nwp output range most times. We need the nwp to help with pattern recognition but I’ll take what history says should happen with the details.

Good luck analyzing a clipper at 150 hours. The day 10 stj thing is what I’m talking about. You’re right about discreet things not showing until inside 4/5 days...but the problem is it’s hard to spend a lot of time analyzing something that hasn’t shown itself yet. Could an unseen vort pop up in the cold window next week? Sure. It’s a pretty suppressive flow though. But maybe that relaxes some. Problem is that’s all pure speculation with no meat to analyze.

I thought that too (and there is some of that) but even some of the members with 990 lows off the coast that bomb us with precip are just rain. You see anything under 240 worth focusing on?

I am legitimately perplexed by the lack of hits day 10-15 on the eps and gefs given the h5 look. Even when you examine the mslp and precip...it’s a coastal track. Not cutters. And it’s not warm. Not really cold but below normal the whole period. It looks great. Then you look at the individual member output and it’s a bunch of 36 degree rainstorms from a perfect track miller A storm! Now I see the “wart”. The ridging in Canada gets centered too Far East which cuts off the cross polar flow so we end up with stale cold across the conus after the initial dump next week. But that setup (ridge bear or just west of Hudson Bay) has been a staple of mid winter snows here. In my study it was the second most frequent feature to an NAO block to signal snow. Like an NAO pattern it’s not an arctic cold look but it’s January. Prime climo. Stale cold air should be good enough. It was in Feb 2010. That was the same general airmass, leftover cold from the dump late January that was cut off under blocking across Canada. It was a garbage airmass by Feb 5. Would have been 45-50 degrees if it was sunny with no snowcover. But it worked with storms tracking under us. I know I’m ranting but my god that pattern should work. Maybe it will and guidance is off by a few degrees at range. I hate to bring you know what up with you know who around but seeing a pattern that has been bread and butter for us in the past look “just a couple degrees too warm” in prime climo (literally this is the coldest/snowiest part of the year) really is frustrating.

The longwave pattern still looks as advertised. Problems are with details that cannot be seen in long range.

@frd still no idea what he meant wrt the IO standing wave in 2/3. That’s a cold look in February.

@Bob Chill looking at h5, slp anomalies, precip, temps, I expected to see a lot of hits on 18z gefs...but no. A couple but when I saw the lackluster snow mean I checked out the members. A lot of coastal scrapers or OTS. A couple hits. But the majority that come up are perfect track rain storms according to the members. Odd. I guess a 36 degree rainstorm would still show up as a “below normal day” becauss we suck that much. Just not the profile of a rainstorm. Seriously this is a rain look now...I have a hard time buying that

Strengthen the western ridge or shift it east some...weaken or shift the eastern one west, and you end up with the upper low where we want it. Not a big change at day 12.

Dude if you go out to the midwest in a hot air balloon at about 6,000 feet and blow facing east really hard you might be able to reel this one in.