psuhoffman

It was heading towards 8 but I can’t remember if it actually ever made it. Very similar stall/death as now with the MC warm sst fighting the mjo progression.

I’m generally pessimistic until we see base state changes in the pac. I see a lot of similarities to 2019 when guidance tried again and again to progress the pattern in a logical way but the western pac base state continually thwarted it. That’s a pretty logical mistake for the NWP. It’s important to understand why they are wrong sometimes. Fool me once shame on you… That said there will be fluctuations. The guidance is weakening the NW pac vortex in January. That would help. The location of the pac ridge isn’t likely to change much. It’s well telleconnected to the Nina and western pac base state and TNH combo. However, we can do good if the pac ridge is less amplified and broader. It’s plenty poleward but it’s way too sharp which is digging the pna trough way too much. Even in 2019 there were some instances when the western trough shifted east just enough to get chances with waves. On a more specific front, one way I could see an opportunity in early January would be a scenery similar to the storm in Jan 2019. After the likely cutter we could get enough cold stuck under the block/50/50 for something to attack from the west. The ridge is far enough west for a time to maybe allow enough space for something to squeeze through. Wouldn’t be an amplified system but neither was that 2019 one. That’s one way to get something in this coming pattern.

That’s actually what a typical Nina h5 when the pac ridge is poleward and blocking looks like. But the relentless TNH has been pumping the SE ridge and altering the typical Nina pattern

Good discussion/speculation. If we really are in a phase of increased HL blocking as I suspect (we were long due) and we get a Nino while still near the solar minimum there is obviously potential for a blockbuster winter. We are overdue for one of those also. But there are variables as you all pointed out. I suspect maestro is correct that it would require more than a weak Nino to shake up the incredibly dominant pac base state since 2016. The weak Nino of 2019 didn’t even dent it. How much did the SSW influence that? Dunno but the Nino wasn’t having much affect on the pac even before the SSW. Of course we don’t want a super Nino either as that just floods tropical warmth across the continent. But there are no signs of that and a fairly strong Nino like 1958 can still have a kick ass second half. Even a mediocre Nino for the mid Atlantic like 2004-5 would be a godsend at this point! What type of Nino also matters. An east based Nino is a crap shoot. Some are good some are really bad (see 1992 & 1995!). Basin wide is better so long as it’s not a super Nino and modoki west based is the only super high almost can’t miss indicator of a cold/snowy winter in the mid Atlantic. Hopefully people remember though that many ninos, even ones that end up good like 1958, 1966, and 1987 or decent like 2004-5 or 2015-16 are pretty mild until mid January. I’m ok with the fact our December snow climo sucks but that seems to bother some a lot. But a Nino isn’t necessarily a cure for that. Moving to Vermont or Colorado would be a better plan!

The point of my last post was mostly missed. I wasn’t actually worried about the day 16 op Gfs being right but showing how that run was a good example of how a Nina can be frustrating even if we do get all the pretty h5 colors in the right places.

This is just to highlight why Nina’s can suck even when we get cold. The long range 6z Gfs does dump the trough into the east with as much depth as we can reasonably hope for…but there is no stj so the resultant system is going to miss us to the north.

Just to add to this…we have to be careful using the numerical indexes. The AO is calculated using the 1000mb level which isn’t the most influential on our weather and can be skewed by conflicting anomalies in its domain. I’ll content we had more “help” up top in 2014 then many give that winter credit. This is the mean winter h5 The lower heights in Canada and Iceland effect the AO index but there was a tendency to get ridging over the top from the epo to Scandinavia. Again it’s about degrees. That alone with a bad pac wouldn’t help much. But with an excellent pac, WPO/epo/pna ridge that’s plenty helpful. The net effect if that is a great look Imo. The tpv is displaced in a great spot to get systems rotating around and just under us. And here are 2 of our warning events that had a lot of HL help… Later in Feb and March there was less HL help but by then cold was established and things were set in motion. That also happens. 1996 the blocking broke down before the 2 big storms in January but the wheels were set in motion. 2015 was actually the more anomalous pattern. But as you pointed out it was really only about 2 weeks in Feb and one storm in March (which was a weird trailing wave which almost never works) that delivered all the snow. Maybe it was just luck! But there was an extremely displaced PV in Quebec that acted to simulate similat longwave characteristics that HL blocking would. Those indexes are cheap shortcuts but you really still have to look at the longwave pattern because there are exceptions and times the numbers don’t do reality Justice. I know you know that just wanted to add to your post.

When have I said it’s not a big concern? I’ll make these statements. 1) If this pac base remains it will be really hard to get consistent snow in this area. The last 5 years are very typical of what we should expect in this pac regime. It can snow but it will be slim pickings and storms will be few and far between. 2) I can’t say for sure how much is cyclical and how much is “you know what”. There are some logical possibilities on how warming has made this worse. I’ve mentioned the changes in the typical SST profile in the IO and western PAC favoring convection in hostile locations for cold here AND the expansion of the pac Hadley cell as possible warming related contributing factors. But I can’t prove anything. 3) should I say this everyday 5 times? Scream it’s never going to snow again and cry? Or do what I do and simply get over it and look for whatever opportunities we can manage despite the crappy base state that seems stuck.

@CAPE @Ji this is why I think there is more to this than Nina. The closest example of what we’re dealing with now was actually 2019 which was a Nino! Truth is this has been a consistent pac issue for 5 years through 2 neutral, 1 Nino and 2 Nina’s. This year it’s just even more out of control!

No but neither does a +AO. Most of the snows are when the AO is neg or neutral. Only a few near the top of that graph also. But look at the real issue…none if the AO is +4/5 just like none if the pna is -4/5 like now! If the PNA was +2 but the AO was +5 we would be screaming how we need the AO right now. Truth is we need more than one thing to have a good chance. ETA: there is also a big difference between DCA where that chart was made from and the NW burbs. Places in our forum can do ok snow wise with a -pna -NAO so long as the NAO is more neg than the pna. Lots of 1-3” storms at DCA that were 4-8” not far NW of the beltway. DCA REALLY sucks. It has to be so perfect for it to snow a lot there.

2015. 2016 was bad for a different reason though. We got the typical Nino north pac trough but in typical super Nino style it was too strong and encroached on the west coast too much and this flooded the Continent with mild pac puke much of that winter. 2017 to now the dominant pac base state has been a central pacific ridge which is bad. Our best way to offset that would be the HL but right now the pac is sooooo bad, literally the worst EVER coming up…that’s it’s just a no win no matter what else is in our favor.

If the pacific was REALLY good and the AO wasn’t a train wreck that would work. But the NAO would work if the pac wasn’t flaming poop also. It’s all a balancing act. Fact is it the AO is raging positive or the pac is hot poo we probably aren’t snowing in either scenario. Even when we scored in 2014 @ 2015 absent a great Atlantic it wasn’t garbage. There was often ridging over the top onto the AO domain in 2014. 2015 we had a displaced PV suppressing on the Atlantic side. We can’t score when either is a hot mess on wheels. We need one to be good and the other not to be a floating flaming dumpster fire.

Wrt these “what single factor is most important” arguments it depends on the degree and what combinations were talking about. For instance a mildly positive pna with a +epo/AO/NAO wont to us any good. What I can say is this, historically the -AO/NAO is the single factor that shows up the most in our warning level snows. Again I think we’re falling victim to recency bias because we’ve had a few -NAOs ruined by flat out awful atrocious pacific patterns recently. That’s not necessarily how it would always work. But the pac base state has been so bad lately…yea we need that to relax. But it won’t necessarily do any good if the AO goes to crap. Truth is we need more than just any one thing to be somewhat favorable to get snow.

Dude

Trying to ask this as respectfully as possible. So if you think there is no value to long range forecasting why do you come into the long range thread?

Follow up on the pna. It’s about degrees. Everything is a trade off. See saw wave game! We can do well in a -pna if the equation is balanced by the AO/NAO. That’s not possible when the pna is 5 std dev lol.

Skip to the bold paragraph if you just want the simple simple simple abridged answer… I think we’re falling prey to both recency bias and some attempts to over simplify with the “it’s the Nina” stuff I’m seeing. Let me again post the mean Dec-Feb h5 for all Nina’s the last 30 years to use as a frame of reference. Actually a crazy -pna isn’t a common problem in a Nina. At least no more so than it can be for a time in any enso phase. You can see the tendency for lower heights in western Canada but notice on the means heights are avg in the east and the pac ridge extends into the southwest. Also our temps avg near normal in Nina’s which is actually colder than if you take all other winters but exclude the 3 modoki ninos we’ve had during that time. The 2 major correlations with a Nina are the central pac ridge and weaker STJ. You’re seeing the smoothing of 2 different Nina patterns there though. In a Nina when there is a flatter pac ridge and no HL help we see the pac jet blast N America. But Typically in a Nina pattern when there is a more poleward pac ridge and or some HL blocking we see the cold spread out across N America centered in western Canada but extending into the northeast. Neither typically features what we’re seeing now though! And the current pna is bordering on possibly setting the December record. Last I saw it was just behind as the lowest pna but with what’s forecast the rest of the month I would bet it ends as the most neg pna December ever. Just that fact alone shows we’re dealing with something anomalous that we can’t just attribute to “typical Nina”. This hasn’t happened in any other Nina lol. Now let me simplify our snow chances as I see them based on major phases. It’s the STJ. Both Nina’s and ninos can have variable longwave features and both favorable and negative features and in the last 30 years there isn’t much difference in mean temps in a Nina v Nino. Both can feature cold and warm periods. But a Nino favors more stj and we need that! That stacks the deck that if/when we do get some cold we get a big snow. Look at 1983 and 2016! And if we get lucky and get a good longwave pattern and blocking in a Nino then we get 1987/2003/2010! But that’s not all ninos either. But if you remove all the big stj driven snows from ninos the snow climo wouldn’t look any better than Nina’s! The problem in a Nina is often when we do get long cold stretches without the STJ it’s just dry. We’re too far south to get a lot of snow from pure NS storms. Last thought: we’ve all noticed the pac base state of the last 6 years. And even the Nino of 2019 couldn’t disrupt it much. Maybe this is what happens when you add a second year Niña in top of that base state and so maybe this is the new “typical Nina” if the pac is going to remain in this phase. But we didn’t have this amount of issue with the pna last year once blocking set in. But this is a second year Niña so…

Cyclical. We had 4 Nina’s in 6 years from 1996-2001. Then only 1 in the next 7 years. 4 in 5 years from 2007-2012 then none from 2013-2017.

Except what you’re describing isn’t a La Niña. This is the comp of all Nina’s in the last 30 years. And that’s skewed by a couple of the ninas like 2008 and 2012 that were that way. But those are try outliers. Most Nina’s (if they have blocking) have a suppressed SE ridge and it’s just cold/dry. This isn’t a typical Nina. What you’re describing sounds more like 2002, 2017 and 2020 which were all enso neutral winters.

@CAPE unfortunately the eps is predictably pulling the rug again. I say predictably because it’s not changing anything except the strength of the SE ridge. And we’ve seen that’s being supported by the pac pattern. This is the old day 13.5 Note I’ve identified the placement of all key longwave features. The SE ridge is there but suppressed. However look at the pac. Why is it suppressing the SE ridge? We’ve still not seen any positive changes to the upstream factors. here is the new day 13. Nothing changes in the placement of all the key features. But as it’s getting closer and less smoother out, and the features come into better clarity, predictably the SE ridge is pumping more. That will continue to happen until something changes with the equation of the 3 features I circled in the pac. One of them has to move to shake that up. Or the equation between the Aleutian ridge and NAO needs to flip. If the Aleutian ridge weakens and the NAO ridge is the more dominant that can also work. But so long as those 3 features remain AND the Aleutian ridge is stronger than the NAO ridge we’re going to continue to see the SE ridge trend stronger and kill our changes imo.

I’ll admit not having the expertise to necessarily parse this accurately. Maybe someone else can add value. But one of the things driving the colder expected pattern was that mjo phase 7 is cold in a Nina. However, the soi has been tanking and today is at -27, more Nino than Nina. Just pointing this out because phase 7 in a Nino is warm and looks a lot like what we’re seeing. However, I know the mjo also affects the soi so…

Normally poleward helps, it was one of my optimistic observations. It’s been a more poleward ridge than a mid lat Nina type. But when it is poleward it doesn’t help, it’s so strong it just sharpens the ridge/trough and digs the trough even deeper in the west. We really need it to either shift east a few degrees and extend into western Canada OR simply weaken some. Either works. But I see neither happening until that vortex north of Japan moves. It’s feeding into the already hostile pac base state.

I’d feel better if that vortex north of Japan would move at all. It’s parked there on everything for the next 2 weeks and that feeds into the Aleutian ridge.

Like I said no towel throwing. You all know when I think it’s time to have an epic meltdown and nuke the season I won’t shy away. I can Ji with the best of ‘‘em but I wait until it’s REALLY time. My pessimism is more for the period from Dec 27-Jan 3 which I initially pegged a while ago as a period of opportunity. But ~10 days ago guidance had the equation slightly off. It had the N pac ridge but not to the actual amplitude. We could have worked with this look it that pac ridge was less anomalous. But it’s just too dominant and the downstream effects are more than the NAO can offset for places south of 40. After they is still ambiguous as it should be at that range. History still suggests eventual progression. Also, all we really need is for the pac to back off some. Not a full reshuffle. Even just a period where the pac ridge lessens somewhat and we could work with it. But…I would caution to continue to look at the amplitude and location of the features in the pac and be hesitant to buy the trough in the east until we see adequate signs that equation is changing.

That ridge is living on borrowed time. The pacific ridge and NAO have linked. We no longer have a monster ridge off the west coast to lock the trough in the west. Roll that forward 48 hours and there is a deep trough in the east. Apply basic wave physics. Think of the troughs and ridges as waves. Think of the basic see saw effect. Ridge digs next trough which pumps next ridge…but what if there is a rock thrown in the pond to create conflicting waves? See saw war! Right now the ridge in the pac is stronger than the NAO one. So it’s digging the pna trough too much and pumping the SE ridge more than the NAO can suppress. At least if you’re south of 40. That’s actually one detail guidance got slightly wrong. Overall the day 15 ensembles have been great at the longwave features. People expect too much. We still aren’t that far removed from when anything past 72 hours was a crap shoot. We’ve made amazing progress Imo. But when the current pattern was 15 days away the pac ridge was a little less anomalous and so the NAO ridge had a better chance of winning that see saw fight. Now apply all that to the plot I posted. Look how rye equation has changed. Where are the dominant features and ridges now? What’s happened to the pac ridge/trough relationship that’s been impeding the effects of the NAO? All this is just meant to be a mental exercise because we shouldn’t be analyzing a day 16 op prog like this. But that look would roll forward into a trough in the east.