psuhoffman

I wanted to use last nights Euro to highlight how chaotic the period from the 15-22nd is going to be and why there is a lot of potential and several legit threads IMO but none are likely to resolved early on guidance. I know using an operational at that range for details is silly but all the ensembles agree on the same general pattern evolution and location of key features, the differences are all within the expected margin or error so in this case the euro op can show us what it COULD look like within the paradigm the ensemble guidance is hinting at. But I am NOT saying its going to look exactly like this...my point is actually with all the noise in the pattern there is no way any one run is going to nail all this, I just want to lay out some of the options. Look at the setup for the first threat next week on the euro Initially everything is anchored around the old weakening at this point TPV vortex, feature A. A strong NS SW, C, is rotating around behind while an STJ feature D is swinging by at the same time. A is way too far west for where we actually want it...but luckily on the euro the TPV is elongated east over the top with a feature B swinging through the 50/50 space and creates just enough suppression in the flow. The euro also perfectly phases C and D at almost the ideal spot for us. Without that none of this would work. There is also a kicker E. But look how noisy this is. These features are all interacting. This is not the same as if the vortex was out near 50/50 and left the playing field void of NS interference for some STJ wave to come along and attack the entrenched cold locked in by the 50/50. That is the simple nino path to a HECS and the one guidance can lock in on the general storm idea from 10 days out and we can reasonably get excited at long leads. This has potential, we have had many big snowstorms through history from a similar convoluted setup working out...but it can also fail easily if all these moving parts don't come together and there is no way in hell guidance will consistently show these features run to run correctly at range. For example lose the phase between C and D and its suppressed. Lose that feature B rotating through 50/50 and its a cutter. Change any one of these variables and the whole thing changes one way or another. And what happens with this sets up whatever comes after. Look at the op euro after this storm. This might be an even better setup for a big snowstorm here. But we are getting more NS interaction that ideal or normal for a nino. Look at A/B/C/D out west. How those all interact would determine how this goes. But the atlantic is so damn perfect here we simply need one of those to be dominant enough to dig. Our goalposts on the initial track of any wave ejecting from the west would be HUGE in that setup. But they could all run interference and squash each other during the 3 day window we have here where its perfect for something to come along. Or they could all phase out west and cut off and sit there until its too late. Ideally we would want one of these waves to eject as healthy as possible and slide east. But what happens with the first wave would determine if it even looks that way. The GFS doesn't phase C and D and so it weakly slides a wave off the coast...and the main TPV then doesn't weaken and get pulled into the new phased storm the euro has...and so it gets left behind to drop into the lakes and likely suppress and squash any chance we have for the window I showed on the op euro above. Looking across guidance...it seems we need a more phased solution from wave 1 to have a better chance at the next threat after. Whether that phased storm gives us snow or not...it pulls the old vortext east into the 50/50 and sets up a better scenario for around the 20th. So IMO we really really want to root for a euro win on that regardless of the eventual exact track of that storm. Hit or miss a phased bomb on that 16th storm sets up a better scenario after. But the main point is while this period has a lot of potential and I could see how we get back to back snowstorms...it also is crazy noisy and depends on a lot of NS moving parts that guidance is extremely unlikely to be correct on from any range at all.

Thanks for posting that discussion @CAPE

Some places that get banding will do ok but honestly yesterday I was looking at the midwest (I actually look at shit other than our back yard, I know cray cray) and observed even they are suffering some of the thermal issues we do. Obviously not to the same extent but the boundary is killing them too! In mid January with a 988 low taking theor ideal track, there is rain mixing at times along the lake fronts and surface temps in the mid 30s requiring heavy rates to accumulate. The snowfall results will be pretty pathetic across the region compared to what you would expect given the time of year, track, and intensity of the storm. I observed the same thing on my trip home from Vermont this weekend. At my friends house at 1400 feet there was ~16” with temps in the 20s. But I stopped in Bennington in the Valley Sunday evening and they didn’t have enough snow to cover the grass and it was 34 degrees! They had 2” of slop. Same story the whole way down. When I hit an area that got death banded near Poughkeepsie there was a foot of mash potatoes but places in between without elevation even up in interior New England looked like some Deep South 2” slush event. We are not the only ones having these issues lately. Luckily the longer this general pattern lasts and the deeper into winter we get (SSTs cool some) the colder the default air mass will get so I’m NOT cancelling winter. The pattern flipped right around Xmas. And each successive press of cold has been colder. Eventually we will have a window with a workable airmass and then we have to score! But winter is getting pushed back later and later which shortens our window and obviously since we would have less chances (single math) is gonna hurt our snowfall overall. I don’t agree Winter is extending. If you look back 100 years of records we’ve had past periods that snowed a lot in March. March has been snowier in comparison to early winter so it seems great but in reality it’s not getting snowier than it was historically. What is happening is March climo is being affected way less than Dec/Jan because the waters have cooled by then, so it makes it seem like it’s getting snowier in comparison because it’s not getting less snowy like other months. I probably butchered explaining that. Sorry. This year I am banking on the fact that in a Nino with the juiced STJ and a weak polar vortex we just need a couple weeks to cooperate to go big! We can absolutely dumped on quick if things line up in this kind of pattern. But in a year without a juiced up stj if all we get is a couple months to try to score all our snow it’s just not mathematically likely we get that much when other than ninos it typically takes 4 or 5 legit threats to score a big hit.

The same models runs that predict the mjo also predicted that look. You can’t separate one from the other. You’re choosing to believe the mjo forecast but not the rest of the output from the same run! Cherry picking. Besides the mjo is out of phase 4 by around Jan 17th. The mjo is likely why the guidance has a temporary breakdown of the pattern around Jan 22-28th. That’s the lag. A hostile mjo wave in mid January won’t cause February to be bad. Maybe Feb won’t be good but it won’t be because of what the mjo was on Jan 13-17th! It’s actually so ridiculous I honestly wonder if you’re trolling.

I was curious why the euro weeklies have such a low snowfall mean despite looking good. So I looked at the control. This 30 day pattern only leads to 3” of snow! Despite that look the snowfall remained pretty far north.

http://climod2.nrcc.cornell.edu

If you only look at the last 7 years DC snowfall has been more like southern NC or northern SC used to be.

I agree with this. That was why I used 2010 as the line. Maybe it is a shorter term cycle, probably some of that going on. But since 2010 DC has been more like NC used to be. And Richmond and RDU have become the "deep south".

That trailing "anafront" wave in December. It took a perfect track to give DC a nice little 2-4" snowstorm but was rain, boundary was just too warm, it was cold enough in the mid and upper levels. The boundary is warming faster than the other levels so this is what we will see more and more. And I don't disagree with your assessment, I don't think this past storm was ever a HECS or anything, but I think it would have been a nice 3-6" snow in a slightly colder base state. We haven't lost out on anything MAJOR yet but we are bleeding away all the little events that added up and made a decent year a good one, or a good one a great one. I didn't say we failed yet. We could still get some big storms to work out if we can actually get the WAR knocked down at some point. This could still end up good. But if it continues to fail with what has and looks to continue to be a good overall pattern that matches ones that produced a lot of snow...just saying we might have to consider it just doesn't work anymore.

That kinda just looks like what an ensemble at that range would look like smoothed v an op showing the same general thing. Yet mixed within that mean there are likely some better solutions...but it has all the main features centered in the same location and that TPV is still west of where we need it to give us a high probability for a snowstorm here.

Not yet but we knew coming in the concern. Nino patterns have historically been very snow...but also not very cold...and many of the snowstorms were in patterns that were marginally cold enough even in the past. Would that still work? We have had a couple perfect track rainstorms already. If that keeps happening we have our answer.

Now quite THAT bad...but I will stick this nugget here for reference... Since 2010 in the last 14 seasons DC has averaged 10.6" with a median of 7.8" From 1932-1990 Richmond VA averaged 14.2" with a median of 13.4" From 1930-1990 Greensboro NC averaged 10.6" with a median of 8.3 So since 2010 DC's snow climo has been like central NC was from 1930-1990

For now I am not. I think either we get things right and go on a tear or temps remain an issue and the rest of the season goes this way and we end up REALLY low...so no point changing. If we get to the "relax" with nothing AND the relax starts to look longer than expect that is when I will call uncle.

just a thought... we are about to get the canonical crazy blocking we expect at some point in a nino, but all the guidance is now targeting the upper midwest not the mid atlantic for the snow blitz we expect here. But...what if the warmer reality just means what we expect is happening...its just shifted north!

There were some key details that made that 0z run work. The TPV was elongated to the east as a lobe rotated around which compressed the flow some out ahead. Also, it split the energy of the trough diving underneath the TPV and had a trailing SW kicking the system east more. Those 2 little fluke details are what made it work because the trough axis is actually NOT good and the favored look for an amplified wave would be to cut too far west for us. And those little weird details are not something guidance could possibly get right from that range anyways. That's why I said this is not something I would feel optimistic in until very short leads. WIth the TPV there we would need some discreet details to break out way to mitigate the unfavorable trough axis with not enough confluence to our northeast .

Unless the TPV location changes, but unfortunately guidance seems to be settling in on a general location too far west...either cutter or suppressed are the two most likely solutions. There is room for a win but its a thread the needle solution we need with that TPV there. The op euro at 0z spit out that thread the needle solution so its in there as a longshot possibility, but its just that.

I still think we have a good chance to go on a run if we can just get some of the minor flaws out of the way. We've been flirting with really good looks but with just enough flaws to prevent it all coming together. 1957-58 was pretty high in my analogs and I see some similarities. That can be good or bad depending how you view what I am about to say. I will point out the good and the bad. December 1957 was warm But our area managed a fluke snowstorm the first week of December in an otherwise warm pattern. Not so sure that would even work now given how much December as a whole has warmed since then. A marginal warm storm during a warm pattern on Dec 4 probably isn't an option anymore. Other than that the only snow Baltimore had before February that winter was a 1" clipper in January. This was the mean pattern for January But all 3 major precipitation events that month were rain. The only snow was the 1" clipper. The reason is linked to the ridge centered near 50/50. Looking at each major qpf event that ridge there seems to have allowed an inside track despite what is otherwise a good longwave pattern for the month. But obviously February finally hit and the ridge migrated further north further away from the 50/50 space So the good is there is some precedence even if we strike out in the next 10 days that we could still be on track for a good year overall. We also could still see something come from the next couple weeks. We either need some luck with the interaction between the TPV and the wave around the 15-17th. Or we might get a shot after that as the TPV traverses 50/50. After that I think we relax for a bit before the pattern reloads by February. So in terms of the pattern progression we are still on track. But if we want to be skeptical...would 1958 even still work today? Am I using analogs that given the same longwave pattern imposed on todays warmer climate wouldn't lead to nearly as much snow? Would that early December storm in a warm pattern have worked today? I do think the Feb HECS would but that was a one trick pony month. The other 2 big snows that winter came in mid to late March and Baltimore had a low temperate of 33 degrees for both. If you warm that same scenario just 1C both would have been all rainstorms now. @Terpeast can probably say more conclusively than me, but there could be an argument that what we think of as an EPIC season, might have just been a one storm year with some minor marginal snow/slop events around it...kinda like 2016! Maybe when I look at the pattern from 2016 and say we were unlucky and should have done better...the real truth is I am imposing a historical "normal" that doesn't exist anymore to come to that conclusion and 2016 is what you get now. Even if that is true I think the odds we get at least one big hit are still very high, and I am not one who ever complained about 2016...that storm was so awesome it was worth it. But I know some do complain about that season. Lastly...the pattern has been what was expected. This has been the mean since Dec 25. We just have no snow to show for it. It's been too warm. This is the projected mean the next month Hopefully we get some snow from it as we take the same favorable pattern into the heart of our snow climo. But at the end of the season, if this ends up a fail...it won't be because the nino didn't couple, or "the pac" or any other BS nonsense. The pattern is taking on and projects to continue to have canonical nino characteristics that have lead to a lot of snow here though our history. We have already had several perfect track rainstorms. We are getting our "answer" can this pattern still work. So far that answer has been no. But we have yet to enter when it has produced the most prolific results historically. We will know very soon!

I referenced the MJO wave in my analysis. But its flying...is going to spend 7-10 days in the MC, it's not stalled and cycling there like previous years. By Jan 20th its exiting into the PAC and heading towards our favorable forcing. An 8 day MC traverse ending around Jan 20th is a really poor justification for "cancel the rest of winter".

GEPS agrees

This is what it actually looked like This is what the ensembles said from 5 days out Good luck trying to do better than that on a 5 day forecast. We KNOW global models underestimate mid level warming with these storms when there is no block and locked in confluence...we knew we didn't have that...anyone who was believing those snow maps from 5 days out and not realizing what was probably going to happen...well that is user error not the fault of the tools. They did an amazing job and I had a pretty good idea what was going to happen from a LONG way out. Like I said they are tools not a forecast, and most who know how to use those tools made pretty good forecasts IMO based on them. Weenie posts in this thread does not mean skilled forecasters actually expected a lot of snow in DC 5 days out.

I know you know, just agreeing...for the benefit of the same audience. Spell check is adding some humor to my posts lately

Since I highlighted the issues with the Jan 17th threat earlier I wanted to say it can work. It would just be a much higher probability if the TPV were located further east. But there is one example that worked with the TPV where the guidance has it, and its from this exact time of year and one of our nino analogs. Jan 22 1987 was very similar and worked out. So this can work, just would take lucky timing wrt the wave spacing, the boundary, and the phasing between the SW and the TPV.

It’s a temporary relax. The winter’s over nonsense was started by that clown Cohen. It’s a temporary response to the MC forcing as the mjo progresses and the epo ridge sliding over into Russia. The tpv temporarily traverses the pole but it’s still weak and will get displaced again quickly once forcing gets out of the MC imo.

If the guidance is right about the progression that’s the one that has the highest probability imo. The wave before it has a shot but unless the tpv shifts east of currently shown it needs a lot of timing and amplitude variables to go right. That look there is more classic for a wide margin of error threat where we can survive more synoptic details not being perfect because the long wave flow is set up exactly right.

There is a reason 50/50 is the sweet spot. It leaves enough room for a wave to amply behind it while also creating a westerly flow just above us so the system can’t cut. With the tpv west of there we have to play a balance act. Too strong and it squashes the wave. To weak the wave cuts. It’s a legit threat. But as shown a tenuous one. I’d be honking like crazy if we see that tpv trend closer to the canonical spot. Otherwise as shown it’s not a setup I’d feel good about until much closer leads because of the delicate balance being played there.