psuhoffman

I didn’t run that composite originally. I focused on the more major sets of snowstorms. I’ll see if I can find my data to run it but I think I lost it when my last laptop died. But keep in mind that there are degrees to this. It’s a lot easier to overcome a minorly hostile epo and pna. There aren’t many examples of a big snow when the pna is -3 like it often has been lately.

@Stormchaserchuck1 oh also remember I studied the loading pattern not the day of. Yes a lot of our big snows come with a trough in GOA. But that’s also why we warm up right after. The loading pattern to that big storm was what happened a week before that to establish cold over us then as the pattern breaks down and sends some wave at us with cold in place…that’s how we get the big ones often.

@Stormchaserchuck1 I think you’re saying the same thing but in different terms. I agree our biggest issue is the mid latitudes have warmed. The indexes are just a way of measuring the pattern. It’s a 6 v half dozen debate. But the bottom line is we’re not seeing the level of mid latitude troughs or cold that we need at this latitude as often. Could be AMO. PDO. Some combo. And some is it’s climate change. I don’t have all the answers either just like doing my best to study and guess Wrt the +epo snows I think a decent number of them fell into this grouping which I termed “Hudson bay ridge storms”. This is a composite of those 16 events.

How many times the last 8 years would we have killed to see this across all guidance. I think it’s a combo of discontent with this week and the fact it’s still forever away which is my fault because I started hyping the window when it was like 30 days out. Also I think some bought into the idea we would be colder and get a lot of snow during the period BEFORE that, which makes this feel like a can kick but imo the failure is the -epo -pna +NAO pattern this week has no bearing on what will happen in the next -AO driven pattern.

I ain’t cancelled shit. Im just having dialogue I find educational and interesting with Chuck about effective snowstorm loading patterns overlayed with hypothesizing about how climate factors “could” impact blocking. But this discussion does not mean I’ve changed my mind about the pattern. BTw keep something in mind. For the last 10 days I was kinda debbing next week despite models spitting out crazy stupid snow. The reason was the pattern just didn’t look like a snowy one. I said the guidance at range when it’s not aligned with historical analogs for a pattern usually adjust to the climo for that pattern once inside day 5. And what happened! Well that works both ways! Remember 10 days before Jan 6 when it was a cutter and Ji and I said that made no sense and should adjust. It ended up adjusting so much it fringed me. I’m not worried about what the surface Synoptics are on model runs at 300 hours. I’m way more worried about what the longwave pattern is. The surface will adjust to it 90% of the time.

First of all I love and value our back and forth dialogues. I learn a lot. Sorry if I ever come off confrontational. Recently most of our snow has come that way. But recently we’ve been in a horrific snow drought. And this historical data would suggest why. This is a chart I compiled back in 2019 for every 5” snow at BWI going back to 1948. 88 events. And to be transparent I used a mean of the pattern the 5 days leading up to the snow. That’s because we had some events from blocking where it was flipping positive and by the day of the snow was neutral or positive but the storm was set up by the block. IMO the loading pattern 5 days leading up is more important then the includes the day of the snow. here was the results. Only 12 of the 88 snows were from a -epo +nao. It’s one of the least common snowfall index combos. Overall the epo had no correlation to snow. We had the exact same number of 5” snows with a + as - epo. Also of note the PNA was not the death sentence to snow historically. Yes when a -PDO was combined with other hostile long wave features like a +epo nao ao it was rare. But it was rare to get snow when any of the other 3 indexes were hostile also. A pna alone was a rare way to snow absent other favorable pattern drivers. And if other factors were favorable a -pna didn’t seem to make snow less likely. Actually the most common index setting for snow was -epo, -pna, -AO, -nao. Our most common big snow look was in a -pna!!!! This is because with blocking the troughs in the west would historically slide east under the block not amplify and cut into the block like is happening lately. I theorize that’s been partly the fault of the crazy -pdo cycle amplifying everything out west. The take away though is by far the two most important factors was AO and NAO. The 4 most common snowfall settings was when those were both negative regardless of the value of the epo pna. And it was rare to get a 5” snow in a +AO NAO no matter what the PNA and EPO was also. The data just doesn’t support the idea that epo pna patterns are a likely way to her big snowstorms. It is more murky if you start to look at 2-4” snows. I started that and had to abandon it for time reasons and never got back but prelim results indicated there is more of a correlation between pna epo and those minor snowfalls. But frankly ok a big game hunter and not that concerned with the locating pattern for a 2” snow. Plus almost every one of our 30” winters!includes some 5” snows so we aren’t getting a snowy winter with those 1-4” event patterns anyways. 2014 was the one exception. Actually that one season made up a few of those rare examples on that chart. If you took out 2014 it would look even worse and there would be a negative correlation overall between -epo and snow! The historical data says that season was an anomaly and not something to bank on as a way to get a lot of snow.

@Stormchaserchuck1 you’re 100% right in your observation of trends the last 8 years but have you thought maybe that’s why it’s been by far the least snowy 8 year period in our recorded history! Yes the last 8 years you’re right blocks haven’t been working and guess what that’s a big part of WHY it’s not been snowy! If blocks continue to fail we will continue to underperform our historical snow climo. Doesn’t mean we won’t snow. Yes epo patterns will lead to snow. But not enough! We won’t get many 30” or 40”+ seasons that way!

I mentioned 2014 but that is the ONLY time that this pattern lead to a huge snow year in my lifetime. It’s happened once in 50 years! That isn’t going to adequately replace blocking as a viable path to our big snowfalls. You said yourself epo is more ice than snow signal. AO/nao are snow signals.

From a 30k foot view we NEED blocking to start working again. And I think it will as the extreme -pdo cycle ends. I think because the one anomaly was not that long ago there seems to be a notion that EPO driven patterns can be a vehicle to snow but the fact is our snow climo has always been heavily reliant on anomalous big snow years with a bunch of below “avg” lean snow years in between. And those big years are driven by one thing. Blocking. 9 of the last 10 40” winters in Baltimore are from a blocking regime. The one exception was 2014! That was a unicorn anomaly. We get maybe one snowy winter that way every 50 years! If that’s the only way for us to get a snowy winter we’re pretty much screwed as history says that that kind of thing happens once a lifetime. This is the h5 comp of the other 9 40” winters. We NEED this to work! The issue lately has been blocks have not caused the depth of mid latitude response we need. Look at the depth of the troughs in the mid latitudes under that blocking! The depth is greater than the high latitude heights! Lately the mid latitude heights have not been nearly as low as the blocks heights are high. That’s a problem! To simplify we aren’t getting cold enough under the blocks to make the equation work. Look at 3 recent blocks and the mid latitude response! Where’s the cold!!?? Seriously where is the mid latitude response we need? And forget worrying about here. Where is the depth of cold anywhere in the mid latitudes under any of those blocks!? Compare those to the analogs above of what we need the response to a block to look like! Lately the only time the mid latitudes get truly cold is with epo driven cross polar directly discharged arctic air but that’s not a snowy pattern. It’s just cold. Snowy patterns here are from domestic cold stuck under a block not cross polar arctic shots. Now I’ve said I think the PDO has been 80-90% of the issue. The other 20% is you know what. I’m banking that as the PDO cycle ends we have more luck again. Hopefully I’m not to fast to expect that. The last block did deliver the cold! But if in the next few years the pdo flips and we continue to see this phenomenon it’s time to have a very depressing conversation about our new reality. One I really hope we don’t have to have yet.

Even the GFS has the mjo strongly into 8 by then. I doubt a western trough eastern ridge with that forcing. I’m not wasting time digging into why one op run did that at range. Unless ensembles move they way I’m not worried.

I doubt it. But anything’s “possible”

No idea. Eagles have the better roster by far but they have the best QB/Coach. My gut says either the eagles dominate and win by 2+ scores (or a game were KC scores late to make it look close but it really isn’t) or KC wins a close game again.

Ok I cracked the code. I’m gonna need you all to tell anyone you share weather advice that the last week of February is going to be beautiful. 70 degrees. Tell them you would bet your life that there will be no big snowstorms after Feb 20. They should schedule an outside BBQ in shorts that week!

@mitchnickI think I found the answer wrt ensembles. You know how is the EPS arill has us in like 8” mean over the next 10 days but it’s from 4 waves and none are that high prob. It was similar thing but condensed. Looking at the GEFS and eps from 3-4 days ago the snow was spread out over 60 hours. That’s not unusual for ensembles at range to have timing differences. But the thing is liking at the precip mean it’s clear there was always uncertainty over when and how much to amplify a wave this week between Tues and Thurs. But the big error was they were too far SE with the thermal boundary because even the members that had the trailing wave more amplified had it as snow! We got those means because the members couldn’t agree on exactly which wave but it didn’t matter. They were all snow. What happened was the operational shifted to this solution if a stringer second wave at the same time the guidance realized the thermal boundary was going to press NW after the initial cold push. There were ens members that had this type of progression but they showed snow for the second wave. The unifying error was that they through it was going to be colder than it actually is, or that the boundary was going to stay SE of us all week instead of just one day to be exact.

This could still be decent for DC south, we should probably check out and let them have their fun.

The only one that is too far south is that weak frontrunner wave that happens to come along during a very short window of opportunity when the boundary is far enough south as a transient arctic high slides by to our north between waves...had something actually come along during that 24 hour window we could have got snow...but its such a short window. Otherwise the whole period is what the H5 says it should be...waves going to our NW

That isn't helping if we want to get some snow from the lead wave thingy, but the bigger issue if we wanted to actually get a legit snowstorm from this whole setup is the energy consolidating too much with the second wave. I'm not even sure its accurate to call it that...its really just a bunch of weak waves along the boundary...and a few days ago models were keying on amplifying the whole thing sooner and not leaving any energy behind and that timed up the wave with our very short window of cold in an otherwise hostile period with the cold boundary to our NW. Now they are waiting and amplifying a day later and...well no bueno. The thing that confuses me in this whole mess isnt the result this is exactly what history says should happen, but why in gods name were all 4 ensembles (I saw the UK ensembles were nuts also) so damn sure out of all the possible variables and waves that it was going to amplify exactly the right time to hit us in such a short window we had for snow. That's just weird to me, because there are so many ways this could have gone...so many small tweeks that send it in another tangent...yet all the guidance was like NO WE ARE SURE ITS THIS EXACT WAY and it was the only way that lead to big snow here...and obvsiously they were all wrong...I'd love to dig into what that was about. Why they erroneously saw certainty in what I always saw as in inherently volatile unstable setup.

In reality the storm is going to our NW...a little front runner wave sneaks out ahead when there is still cold and might give snow to our southeast...but in the larger sense what happened is more energy held back and is amplifying a wave too much so that it goes to our NW...which is kinda exactly what this pattern says is the most likely outcome, unfortunately. It's why I had a hard time getting excited by those crazy snow means, it just didn't fit the longwave pattern.

If the spacing was a little less between the two displaced TpV lobes it could have been a better threat but it’s probably, like you said, a rain to snow deal because of that. If the storm ahead of it trends more amplified it might have a better chance. But it’s not unusual for it to take one wave amplification after a block develops before we get the setup right for a bigger storm here.

To be fair I actually started calling for that period before the models latched on by about a week. But…it doesn’t ALWAYS work. Im not perfect in these calls, frankly I think it’s impossible to be with long range stuff. Remember last year. I utterly failed. So even if I get this one right I’m only 50% on these “bold” calls recently. Have to go way way back many years to find the last time before those that I was really excited about a window a month out. It’s been mostly crap for a while.

I’d prefer it a little more tucked 966 lol

Actually when I made the call for mid Feb to Mid March it was based on analogs and timing out seasonal cyclical progressions of the AO and MJO. At the time no guidance showed much, but it emboldened by feelings when they came around to what I was thinking. They all aligned. Analogs to cold enso years when we get a significant -AO in early January have another drop sometime mid Feb into March. I didn’t by the collapse of the MJO because the guidance did that last cycle. I timed it into 8/1/2 for Feb 15 on. And the AO has been in a very consistent cycle of huge drops and slow rise then repeat and it was timed up to so the same mid Feb. Basically everything is look at to try to decipher long range clues was pointing the same direction and that rarely happens. The only thing to give pause was it was going against the recent late seasonal patterns as you pointed out. But I just have the sense we’ve broken oit of the dominant pacific cycle of the last 6 years. Not saying the pacific is great now but I think we are in the middle of a PDO phase change and we are not seeing the same degree of hostile influence we did recently. So I went with my gut that this would be different and another cycle of -AO and hopefully snowier was coming. I also like the idea of cycling the general Jan pattern again but with the shorter wavelengths of late winter. Should be a stormier period.

I think after the wave around the 16th passes we have a solid week where any decent wave is a major threat.

Oh none of this has changed my mind about what’s coming. I always liked later in Feb better once the blocking gets going and has time to impact the storm track.

A couple days ago the runs that gave us 12-18” that second wave didn’t even exist. The models were totally wrong on which wave to amplify. They were keying on the wrong SW all along. Now they’re jumping on a SW they washed out before and it’s canibalizing our storm.