ENSO Discussion

[Webberweather53]

That’s still a neutral AMM change over the last month, sure the last few decades and esp the 2010s have featured rapidly ascending AMM regimes but why do you think it doesn’t matter what the current AMM state is now? I Why do you think we’re in the same regime as 1995-2012 era when it’s blatantly obvious we’re not after the 2015-16 NIno w/ a cold Atlantic and Indian Ocean? The same interannual variability and AMM behavior evident over the past few decades isn’t as applicable here as you’re touting it to be. I think you’re grasping at straws here because this is a RECORD negative regime, it will take a miracle to bring it back significantly into positive territory and we have made no progress whatsoever in the last month or so as the SST graphic you posted shows with the South Atlantic continuing to disproportionately warm compared to the North Atlantic, so the AMM grows more negative still. It definitely matters where we’re starting here lol. Both the CFSv2 and EPS show low frequency coupling beginning within the next 1-2 weeks and/or are already initializing it over the Pacific basin, do you really believe ALL the models are that bad, again I think you’re stretching it here. Additionally, you’re still clinging to this nonsense that we aren’t drawing from the warmpool, I guess you don’t see the obvious downwelling KW passing the dateline in the CPC analyses (even if its a weak wave). Integrated warm water volume east of the dateline is 5th highest on record for June, for the most part we’re only behind strong El Niños like 1997, 2015, 1991, etc and have more WWV in the EP than the peaks of recent weak El Ninos. There’s multiple ways to get to the same answer and we are still ahead of those years in terms of cumulative forcing. It’s also probably not a good idea to blindly assume there won’t be anymore significant WWB forcing for the remainder of the summer as we saw in 2014 with tropical forcing shifting back towards the Pacific and W hem later this month.

[Webberweather53]

CFSv2 day 1-5 forecast on Carl Schreck’s site already shows low frequency coupling (purple contours) over the Pacific... Sorry but I seriously doubt all the models are going to be that unreliable s.t they can’t get the forecast remotely correct just several days out, again I think you’re really making a stretch here.

[Phil]

That’s still a neutral AMM change over the last month, sure the last few decades and esp the 2010s have featured rapidly ascending AMM regimes but why do you think it doesn’t matter what the current AMM state is now? I Why do you think we’re in the same regime as 1995-2012 era when it’s blatantly obvious we’re not after the 2015-16 NIno w/ a cold Atlantic and Indian Ocean? The same interannual variability and AMM behavior evident over the past few decades isn’t as applicable here as you’re touting it to be. I think you’re grasping at straws here because this is a RECORD negative regime, it will take a miracle to bring it back significantly into positive territory and we have made no progress whatsoever in the last month or so as the SST graphic you posted shows with the South Atlantic continuing to disproportionately warm compared to the North Atlantic, so the AMM grows more negative still.

1) I’m not saying the AMM will wildly swing back into super positive territory. Too much thermal inertia for that. But my guess is that it recovers to neutral or weakly positive. The seasonality matters, again, because of what’s driving it. The -AMM is not favored in recent decades during the monsoonal forcing/warm season circulation state. It yields to the west-Pacific/IPWP under an increasingly axisymmetric forcing/HC regime that flips the NAO to negative during August and September most years.

 

It definitely matters where we’re starting here lol. Both the CFSv2 and EPS show low frequency coupling beginning within the next 1-2 weeks and/or are already initializing it over the Pacific basin, do you really believe ALL the models are that bad, again I think you’re stretching it here.

What are you using for a low-freq filter of the EPS? I’m seeing plenty of intraseasonal variability amongst the ensemble members, albeit the degrees vary too. Usually the safe bet (IMO) is during the warm season is to go bullish on the projected intraseasonal components and bearish on the projected low-freq components, in the absence of any pre-established low-freq regime (of which there has been none...yet).

 

And yeah (especially during the warm season) models are catastrophically awful at picking up intraseasonal forcing at-range. Especially the CFSv2. I never even look at the CFSv2 anymore..it’s an over-parameterized piece of junk in my book.

 

I’ve never seen the CFSv2 it pick up intraseasonal variability accurately beyond ~ 3 weeks during the warm season. Ever. If you can show me otherwise, I’d be shocked.

 

Additionally, you’re still clinging to this nonsense that we aren’t drawing from the warmpool, I guess you don’t see the obvious downwelling KW passing the dateline in the CPC analyses (even if its a weak wave). Integrated warm water volume east of the dateline is 5th highest on record for June, for the most part we’re only behind strong El Niños like 1997, 2015, 1991, etc and have more WWV in the EP than the peaks of recent weak El Ninos.

It’s not just that it’s a weak wave..but it’s much weaker than the one before it. That’s the problem I see (in the absence of additional WWB/OKW activity), because the thermocline return will be loaded with fluid inertia given the strength of the first wave, and a weak, impotent OKW alone won’t be enough without additional support, IMO.

 

There’s multiple ways to get to the same answer and we are still ahead of those years in terms of cumulative forcing. It’s also probably not a good idea to blindly assume there won’t be anymore significant WWB forcing for the remainder of the summer as we saw in 2014 with tropical forcing shifting back towards the Pacific and W hem later this month.

The subsequent WWB activity/dateline forcing is indeed what I’m watching for. The last round of intraseasonal forcing kind of circumvented the WPAC/dateline area due to emergent monsoonal dynamics and an outrageous amount of poleward +AAM propagation.

 

That’s not something you typically see in developing Niño years (can’t find any cases of it). If the next intraseasonal cycle fails to remain coherent through the dateline and/or flip U-winds west of the dateline for a prolonged period of time..then it would statistically preclude a niño since no non-canonical niño has ever failed to produce WWBs after mid-July.

[Webberweather53]

1) I’m not saying the AMM will wildly swing back into super positive territory. Too much thermal inertia for that. But my guess is that it recovers to neutral or weakly positive. The seasonality matters, again, because of what’s driving it. The -AMM is not favored in recent decades during the monsoonal forcing/warm season circulation state. It yields to the west-Pacific/IPWP under an increasingly axisymmetric forcing/HC regime that flips the NAO to negative during August and September most years.

 

What are you using for a low-freq filter of the EPS? I’m seeing plenty of intraseasonal variability amongst the ensemble members, albeit the degrees vary too. Usually the safe bet (IMO) is during the warm season is to go bullish on the projected intraseasonal components and bearish on the projected low-freq components, in the absence of any pre-established low-freq regime (of which there has been none...yet).

And yeah (especially during the warm season) models are catastrophically awful at picking up intraseasonal forcing at-range. Especially the CFSv2. I never even look at the CFSv2 anymore..it’s an over-parameterized piece of junk in my book.

I’ve never seen the CFSv2 it pick up intraseasonal variability accurately beyond ~ 3 weeks during the warm season. Ever. If you can show me otherwise, I’d be shocked.

 

It’s not just that it’s a weak wave..but it’s much weaker than the one before it. That’s the problem I see (in the absence of additional WWB/OKW activity), because the thermocline return will be loaded with fluid inertia given the strength of the first wave, and a weak, impotent OKW alone won’t be enough without additional support, IMO.

 

The subsequent WWB activity/dateline forcing is indeed what I’m watching for. The last round of intraseasonal forcing kind of circumvented the WPAC/dateline area due to emergent monsoonal dynamics and an outrageous amount of poleward +AAM propagation.

That’s not something you typically see in developing Niño years (can’t find any cases of it). If the next intraseasonal cycle fails to remain coherent through the dateline and/or flip U-winds west of the dateline for a prolonged period of time..then it would statistically preclude a niño since no non-canonical niño has ever failed to produce WWBs after mid-July.

But we’re not talking about intraseaonal variability beyond 2-3 weeks from now, I have specifically said over and over again that this forecast is inside 1-2 weeks, in fact inside 1-5 days is when the VP200 will envelope onto the entire basin. Sure you’re not claiming it will become raging or significantly positive but what makes you think it’ll even go to neutral anytime soon because the graphic up showed earlier only showed an intensifying -AMM with the southern Atlantic warming more than the north, I honestly don’t know why you think we’re still in the post 1997-98 era globally and it’s similar to the last few decades because it’s obviously not with a cold Indian Ocean and a -AMO. I’d be very careful in assuming this because weve has seen this trend the past few decades so we’re automatically slated for a very substantial AMM recovery. Even if the AMM recovers a lot it still may be negative and significantly at that. Quite frankly I don’t think you understand that this year will have a bigger hill to climb than any other year ever observed before it, good luck, but hey at least you admitted that the initial state matters Its also nice to see you finally came to your sense and admitted we’re drawing from the warm pool after blatantly denying it for the past week or so the last Kelvin Wave was no slouch and this one while small will reinforce what’s already there, the warm water volume east of the dateline is actually ahead of all modern Niño head fakes atm, if we back off it won’t be anywhere near as easy as you think nor does a lack of subseasonal forcing in the next month or so automatically preclude a Nino as you’re claiming. Even though u may protest, we simply don’t have enough data to jump to conclusions like that, if there’s anything you should take away w/ ENSO it’s that the modern observed range of variability represents only an infinitesimal fraction of late Holocene variability that’s somewhat applicable to modern ENSO...

[Guest happ]

Sitting at the feet of professors - love the discussion 

[Phil]

Re: Hurricane Beryl, the AMM, and ITCZ width. Not the most prolific CCKW, but Beryl’s latitude is exceptionally low, more towards those warmer near-equator waters underneath the cold horseshoe.

 

I wonder if this will be a season with relatively fewer recurvatures (and fewer storms altogether) but produce a few equatorward-shifted MDR-style genesis events along with the more-favored homebrew stuff (given off-eq EPAC ventilation).

 

I also think there’s a solid chance we’ll have a more delayed peak this year, towards the equinox into early October.

[weatherfan2012]

Re: Hurricane Beryl, the AMM, and ITCZ width. Not the most prolific CCKW, but Beryl’s latitude is exceptionally low, more towards those warmer near-equator waters underneath the cold horseshoe.

I wonder if this will be a season with relatively fewer recurvatures (and fewer storms altogether) but produce a few equatorward-shifted MDR-style genesis events along with the more-favored homebrew stuff (given off-eq EPAC ventilation).

I also think there’s a solid chance we’ll have a more delayed peak this year, towards the equinox into early October.

it will be interesting to see if we get an East coast tropica system hit this fall would be fitting.

[Phil]

But we’re not talking about intraseaonal variability beyond 2-3 weeks from now, I have specifically said over and over again that this forecast is inside 1-2 weeks, in fact inside 1-5 days is when the VP200 will envelope onto the entire basin. Sure you’re not claiming it will become raging or significantly positive but what makes you think it’ll even go to neutral anytime soon because the graphic up showed earlier only showed an intensifying -AMM with the southern Atlantic warming more than the north, I honestly don’t know why you think we’re still in the post 1997-98 era globally and it’s similar to the last few decades because it’s obviously not with a cold Indian Ocean and a -AMO.

You can’t even calculate low-frequency components in such close range. You typically filter on a 30-day resolution for standing waves/etc. The CFSv2 is just losing the intraseasonal components after ~ 20 days, as it always does.

 

Regarding the 1998-2016 regime, we’re actually closer to agreeing than you realize.

 

So, I agree that we’re terminating the 1998-2016 circulation regime (which was dominated by that “drinking bird” style function of resonance, as it relates to the derived seasonality of the annular modes under the west-shifted Pacific Hadley/Walker engine, with the effects of the enhanced Indonesian throughflow/warm IO completing the equator/pole feedback loop through the seasonal cycle, which is reflected by the meridional modes).

 

It was a period of broad z-cell expansion/off-equator heating as the mass circulation strengthened above the acisymmetric changes in tropopause height. It really contributed to climate warming as well, given the resulting weakening of the meridional temperature gradient and reduction in low latitude cloud cover, which will now begin to reverse over the next decade and possibly beyond.

 

The difference is, I don’t think we can accomplish this transition in just one year. There are a multitude of structurally-analogous transitions expressed clearly in the paleoclimate data (suggesting some structural homogeneity in the Holocene EOFs), however, the vast majority of them occurred over a decade or two. The last time we observed a single-year flip (of the matching sign and structure) was just before the 8200kr cooling event, back in the early part of the interglacial. It requires an extraordinary build-up of disequilibrium to produce such an outrageously fast reversal in such an inertially-laden system (of the suggested direction).

 

What you’re predicting is essentially a Bond event. And we definitely don’t want one of those.

 

I’d be very careful in assuming this because we’ve seen this trend the past few decades so we’re automatically slated for a very substantial AMM recovery. Even if the AMM recovers a lot it still may be negative and significantly at that. Quite frankly I don’t think you understand that this year will have a bigger hill to climb than any other year ever observed before it, good luck, but hey at least you admitted that the initial state matters Its also nice to see you finally came to your sense and admitted we’re drawing from the warm pool after blatantly denying it for the past week or so the last Kelvin Wave was no slouch and this one while small will reinforce what’s already there, the warm water volume east of the dateline is actually ahead of all modern Niño head fakes atm, if we back off it won’t be anywhere near as easy as you think nor does a lack of subseasonal forcing in the next month or so automatically preclude a Nino as you’re claiming. Even though u may protest, we simply don’t have enough data to jump to conclusions like that, if there’s anything you should take away w/ ENSO it’s that the modern observed range of variability represents only an infinitesimal fraction of late Holocene variability that’s somewhat applicable to modern ENSO...

Well again, it’s not that I’m just assuming we’ll follow recent climo w/ AMM. Rather, it’s the *reasons for the existence of* that seasonality that leads me to believe it won’t terminate in just one year, and *those reasons* also act on peripheral dynamics related to ENSO. Even if the sign is still neutral or somewhat negative.

 

FWIW, I never claimed we had zero draw from the warm pool. I just don’t think there’s enough of it. With the big OKW still in the EPAC, we’d still technically be “drawing from the warm pool”, even in the absence of the weak follow-up.

 

I’ll get more bullish on a niño if persistent westerly anomalies develop between 120E and the dateline by the end of August. If not, the chances of a niño drop to almost zero.

[Webberweather53]

You can’t even calculate low-frequency components in such close range. You typically filter on a 30-day resolution for standing waves/etc. The CFSv2 is just losing the intraseasonal components after ~ 20 days, as it always does.

Regarding the 1998-2016 regime, we’re actually closer to agreeing than you realize.

So, I agree that we’re terminating the 1998-2016 circulation regime (which was dominated by that “drinking bird” style function of resonance, as it relates to the derived seasonality of the annular modes under the west-shifted Pacific Hadley/Walker engine, with the effects of the enhanced Indonesian throughflow/warm IO completing the equator/pole feedback loop through the seasonal cycle, which is reflected by the meridional modes).

It was a period of broad z-cell expansion/off-equator heating as the mass circulation strengthened above the acisymmetric changes in tropopause height. It really contributed to climate warming as well, given the resulting weakening of the meridional temperature gradient and reduction in low latitude cloud cover, which will now begin to reverse over the next decade and possibly beyond.

The difference is, I don’t think we can accomplish this transition in just one year. There are a multitude of structurally-analogous transitions expressed clearly in the paleoclimate data (suggesting some structural homogeneity in the Holocene EOFs), however, the vast majority of them occurred over a decade or two. The last time we observed a single-year flip (of the matching sign and structure) was just before the 8200kr cooling event, back in the early part of the interglacial. It requires an extraordinary build-up of disequilibrium to produce such an outrageously fast reversal in such an inertially-laden system (of the suggested direction).

What you’re predicting is essentially a Bond event. And we definitely don’t want one of those.

 

Well again, it’s not that I’m just assuming we’ll follow recent climo w/ AMM. Rather, it’s the *reasons for the existence of* that seasonality that leads me to believe it won’t terminate in just one year, and *those reasons* also act on peripheral dynamics related to ENSO. Even if the sign is still neutral or somewhat negative.

FWIW, I never claimed we had zero draw from the warm pool. I just don’t think there’s enough of it. With the big OKW still in the EPAC, we’d still technically be “drawing from the warm pool”, even in the absence of the weak follow-up.

I’ll get more bullish on a niño if persistent westerly anomalies develop between 120E and the dateline by the end of August. If not, the chances of a niño drop to almost zero.

CFSv2 initialization already shows low frequency -VP200 signal in the WP, it propagates ever so slightly east over the course of the month. U never claimed we had 0 draw from the warmpool you’re comments several days ago suggest otherwise, the fact that I had to convince u there was actually a downwelling KW in the CP should be your big clue but I’ll let you believe what u want As for this regime flip globally you’re taking it way out of context nor do I think you know what I’m really arguing here (which is normal for us tbh lol and me included as I often take things the wrong way haha) It’s fine to believe that the seasonality in the ITCZ contributing to AMM behavior but the long term climatological behavior of the monsoon is already somewhat factored in, you are going to need another mechanism to significantly flip it to neutral or positive. If it stays negative then that really defeats the purpose of one of your pillars for a Niño head fake, a less negative but still negative AMM is conducive to Nino development, you’re gonna need to look elsewhere if that transpires.

[Webberweather53]

But let’s say you’re right here and we fade to warm neutral then try to pull out an El Niño next year, talk about pulling a page once again out of the 19th-early 20th century ENSO playbook. I definitely see it happening if the AMM collapses to neutral but I’m very skeptical for obvious reasons because this regime really got going as early as last winter and we are sitting near record lows, only one way to go from here lol

[Webberweather53]

Re: Hurricane Beryl, the AMM, and ITCZ width. Not the most prolific CCKW, but Beryl’s latitude is exceptionally low, more towards those warmer near-equator waters underneath the cold horseshoe.

I wonder if this will be a season with relatively fewer recurvatures (and fewer storms altogether) but produce a few equatorward-shifted MDR-style genesis events along with the more-favored homebrew stuff (given off-eq EPAC ventilation).

I also think there’s a solid chance we’ll have a more delayed peak this year, towards the equinox into early October.

I agree with all of the above, I got a kick out of Dr Ventrice getting salty earlier today because he made another one of his infamous bold predictions expecting no TCs in the Atlantic in July lol. Literature shows cold AMOs favor lower latitude cyclones and less recurves (go figure because the Azores-Bermuda high is usually stronger in cases like this, if we had a solid Niña in place I’d probably be at least mildly concerned about the steering pattern (1985 for ex w/ a Niña, +PMM, -AMO)). You tend to see a lot of low latitude very intense TCs in the Caribbean, Gulf, & extreme SW Atlantic in the 2-3 years following multi-yr Niños in the cold AMO era. (1915, 1916, 1979, 1980, 1988, 1989, etc). Michael Lowry also showed a nice graphic several weeks ago showing that cold AMO years peak significantly later... The major caveat we have this year against 1970-1994 is an active AEW train and a wet Africa still seems to be a major player on the globe even after the 2015-16 Niño. Storms like Beryl even in a crappy environment are certainly more likely when the Sahel is wet, and you have stronger, more numerous AEWs...

[Webberweather53]

I just looked at the EPS U850 monthly product for the equatorial Pacific from over a month ago and I have to say I’m very impressed, the model correctly sniffed out the subseasonal forcing signal completely skipping the WP and the WWBs in the far eastern Pacific that occurred last month. Hopefully I can phone a friend in high places to let me have a peak at its opinion thru the end of August even though it should be taken with a grain of salt. The latest forecast I saw showed WWBs in the WP beginning in mid July so I guess we’ll see

[Phil]

Uhhh yea you can it’s called the other month before the next 5 day period maybe, initialization already shows low frequency -VP200 signal in the WP. Lol.

There has been no decipherable low frequency signal in the VP200 anomalies during the last 6 weeks. Can you show me otherwise?

 

There’s an intraseasonal wave responsible for the negative VP200 anomalies across the Indo-Pacific, but that’s opposite of the low frequency structure of developing Niños, which have positive VP200 anomalies there.

 

See our recent example cases for developing niños:

 

 

Versus modeling for the next 2 weeks:

 

 

It just so happens that the GEFS/CFSv2 have a prolific bias towards this WHEM convection (as I’m sure you’re aware of) and it’s in the nature of seasonal guidance to over-couple to projected SSTAs at the expense of intraseasonal variability (I’m sure you’re aware of that too).

 

Yes, forcing should propagate eastward into the VP200 EOF for developing niños, but that doesn’t mean it will magically stop propagating and stay there. No, it will continue propagating and recycle. How much residual convection remains after the wave recycles is the question, IMO.

 

The CFSv2 abruptly shuts down the intraseasonal component, completely, over the span of 5 days, and keeps all anomalous convection locked in the EPAC/WHEM...that’s not going to happen You seldom see a switch flip like that even during high amplitude ENSO events. You could argue 1997 pulled it off, but what was during the equinox in a transition into a canonical style super niño, lol.

 

U never claimed we had 0 draw from the warmpool you’re comments several days ago suggest otherwise, the fact that I had to convince u there was actually a downwelling KW in the CP should be your big clue but I’ll let you believe what u want

If that’s how it came off, I apologize for the misleading phrasing. That certainly wasn’t the message I was trying to convey (that somehow there was zero warm pool draw..that would be stupid since it’s impossible not to have warm pool draw in the presence of a downwelling OKW of any kind).

 

As for this regime flip globally you’re taking it way out of context nor do I think you know what I’m really arguing here (which is normal for us tbh lol and me included as I often take things the wrong way haha) It’s fine to believe that the seasonality in the ITCZ contributing to AMM behavior but the long term climatological behavior of the monsoon is already somewhat factored in, you are going to need another mechanism to significantly flip it to neutral or positive. If it stays negative then that really defeats the purpose of one of your pillars for a Niño head fake, a less negative but still negative AMM is conducive to Nino development, you’re gonna need to look elsewhere if that transpires.

Haha, maybe so. Wouldn’t be the first time.

 

Though I would vehemently argue that nothing in the climate system occurs in a vacuum..it’s all connected in one way or another. The AMM is no exception..a flip negative requires changes to large scale boundary conditions.

 

As for 2018, what I’m looking for re: AMM, is how much it recovers (if at all) during the next 6 months.

 

If the magnitude of the recovery (regardless of the sign of the index) is as large or larger than normal, that would indicate to me that boundary conditions are less favorable for a niño (which is what I expect).

 

If the AMM recovery is smaller, or (god forbid) nonexistent, then it would indicate a drastic reorganization of the climate system, a higher likelyhood of a niño, and probably a multidecadal shrinking of the IPWP, given the necessarily large amplitude of the trigger.

[Phil]

I just looked at the EPS U850 monthly product for the equatorial Pacific from over a month ago and I have to say I’m very impressed, the model correctly sniffed out the subseasonal forcing signal completely skipping the WP and the WWBs in the far eastern Pacific that occurred last month. Hopefully I can phone a friend in high places to let me have a peak at its opinion thru the end of August even though it should be taken with a grain of salt. The latest forecast I saw showed WWBs in the WP beginning in mid July so I guess we’ll see

Interesting. I’ll have to check it out. If the EPS is indeed suggesting low frequency EPAC/WHEM coupling, that is definitely a bigger deal than the CFSv2 suggesting it. Because the CFS/GEFS are always trying to throw convection into the WHEM.

 

Remember last year how Dr. Paul Roundy (whom I respect immensely) was constantly posting those images of the CFSv2 projecting a flip to westerlies across the eastern and central Pacific? Of course it never happened..fooled me too.

[Phil]

I agree with all of the above, I got a kick out of Dr Ventrice getting salty earlier today because he made another one of his infamous bold predictions expecting no TCs in the Atlantic in July lol. Literature shows cold AMOs favor lower latitude cyclones and less recurves (go figure because the Azores-Bermuda high is usually stronger in cases like this, if we had a solid Niña in place I’d probably be at least mildly concerned about the steering pattern (1985 for ex w/ a Niña, +PMM, -AMO)). You tend to see a lot of low latitude very intense TCs in the Caribbean, Gulf, & extreme SW Atlantic in the 2-3 years following multi-yr Niños in the cold AMO era. (1915, 1916, 1979, 1980, 1988, 1989, etc). Michael Lowry also showed a nice graphic several weeks ago showing that cold AMO years peak significantly later... The major caveat we have this year against 1970-1994 is an active AEW train and a wet Africa still seems to be a major player on the globe even after the 2015-16 Niño. Storms like Beryl even in a crappy environment are certainly more likely when the Sahel is wet, and you have stronger, more numerous AEWs...

I was about to ask you about that. I haven’t read enough about Sahel rainfall or hurricane activity in general to develop an informed opinion, but have you done abt research on the relationship between the Mascarene High/SIOD and Atlantic hurricane activity in the subsequent season? I feel like there’s something there but I haven’t had the time or motivation to dig into it.

 

And yeah, Dr. Ventrice was going for the Hail Mary with that one. If the system off the Carolinas develops, his forecast for a dead July will look pretty bad (though kudos to him for sticking his neck out there).

[Phil]

But let’s say you’re right here and we fade to warm neutral then try to pull out an El Niño next year, talk about pulling a page once again out of the 19th-early 20th century ENSO playbook. I definitely see it happening if the AMM collapses to neutral but I’m very skeptical for obvious reasons because this regime really got going as early as last winter and we are sitting near record lows, only one way to go from here lol

You have a point re: it being difficult to avoid some type of recovery in the AMM following record lows. So I’m not going to try and claim that I was “correct” if the recovery is modest. Obviously I’m expecting something bigger, more similar to what happened in 1989. If I’m wrong I’ll be the first one to admit it.

 

And yeah, it would be interestino to repeat the “slow walk” to El Niño again, after it just happened in 2014. Might be time to consider the effects of low solar on ENSO tendencies (paleo data unanimously indicates that more frequent niños and +PDO/ weak Asian monsoons are the typical climatological responses to minimums in solar activity).

[Phil]

This is actually a pretty bizarre situation...it actually looks like the entire equatorial Pacific overturning cell has been knocked onto its side, creating the fabric of spatial dissonance. I think we’ll need to widen our 5*N/5*S hovmollers to accurately capture this!

 

The NH wavecycle is clearly way ahead of the SH. Note the westward retraction of the SH subsurface warmth bifurcating from the first OKW (which is already well into the EPAC) recharging that weak OKW in the WPAC, while the NH is just a massive OHC void propagating westward ahead of the initial OKW. So disorganized.

 

http://www.cpc.ncep.noaa.gov/products/GODAS/pent_gif/xy/movie.d20.gif

 

http://www.cpc.ncep.noaa.gov/products/GODAS/pent_gif/xy/movie.d20.gif

 

Something significant must have perturbed the tropical Pacific ocean circulation last winter. My guess is the SSW had something to do with it, but that’s just a guess.

[Phil]

And then we have this behemoth upcoming. Duration matters (and this is intraseasonal) but as modeled it would be the strongest ever trade burst to ever occur after 7/1 in a developing niño year west of 150W in the satellite era, unless I’m missing one somewhere.

 

[Webberweather53]

Interesting. I’ll have to check it out. If the EPS is indeed suggesting low frequency EPAC/WHEM coupling, that is definitely a bigger deal than the CFSv2 suggesting it. Because the CFS/GEFS are always trying to throw convection into the WHEM.

 

Remember last year how Dr. Paul Roundy (whom I respect immensely) was constantly posting those images of the CFSv2 projecting a flip to westerlies across the eastern and central Pacific? Of course it never happened..fooled me too.

 

Here's what the EPS has in store through most of the rest of July, obviously we have a huge trade wind burst in the upcoming week, but we then have a substantial WWB west of the dateline but intriguingly it doesn't propagate east of the dateline like the last one, the EPS does have a modest wet bias over the Maritime Continent so I wouldn't take these forecasts at face value but it's done a reasonably good job even at this range over the past few months.

http://blog.southernwx.com/wp-content/uploads/2018/07/ekOOUrQ9.jpg

 

 

 

Here its forecast from over a month ago which correctly sniffed out the MJO skipping the WP even 4 weeks in advance! That's pretty impressive

http://blog.southernwx.com/wp-content/uploads/2018/07/w5teOGR3.jpg

[Webberweather53]

Here's what the EPS has in store through most of the rest of July, obviously we have a huge trade wind burst in the upcoming week, but we then have a substantial WWB west of the dateline but intriguingly it doesn't propagate east of the dateline like the last one, the EPS does have a modest wet bias over the Maritime Continent so I wouldn't take these forecasts at face value but it's done a reasonably good job even at this range over the past few months.

http://blog.southernwx.com/wp-content/uploads/2018/07/ekOOUrQ9.jpg

 

 

 

Here its forecast from over a month ago which correctly sniffed out the MJO skipping the WP even 4 weeks in advance! That's pretty impressive

http://blog.southernwx.com/wp-content/uploads/2018/07/w5teOGR3.jpg

 

 

Here's what the latest 45 day forecast shows, look how the trades are virtually dead in the Atlantic from mid July onward, that would favor a major, prolonged warming in the tropical Atlantic. If this verifies I'll certainly start to have faith in a head fake to warm neutral ENSO, classic late 19th-early 20th century behavior (again)... We also just completely lost whatever +PMM we had going into the summer granted it usually fades after the spring, but this doesn't help my confidence in a weak-moderate NINO this year. Really need the tropical Atlantic to stay cold to keep this solution alive...

 

http://blog.southernwx.com/wp-content/uploads/2018/07/jimcThLS.jpg

[Webberweather53]

And then we have this behemoth upcoming. Duration matters (and this is intraseasonal) but as modeled it would be the strongest ever trade burst to ever occur after 7/1 in a developing niño year west of 150W in the satellite era, unless I’m missing one somewhere.

 

 

 

Yeah 2009 says hi, the dateline trade wind burst in July was somewhere in the ballpark of 8-10 m/s, pretty close to what's forecasted in the next week or so. It still amazes me that this year found a way to produce a borderline strong El Nino, you wouldn't know that from looking at the U850 evolution. Like this year however 2009 had a huge OKW early in the game to get it thru the summer (this year's was bigger actually) and like w/ most weak-moderate events (although it could be argued 2009-10 was strong), the trades relaxed after the September equinox and that was all she wrote. This pretty remarkable east-central Pacific trade wind burst this late in the game still would not be enough to convince me of a head fake given what happened in 2009-10. It's actually borderline scary how similar the trade wind evolution this July looks to July 2009.

[Webberweather53]

This is actually a pretty bizarre situation...it actually looks like the entire equatorial Pacific overturning cell has been knocked onto its side, creating the fabric of spatial dissonance. I think we’ll need to widen our 5*N/5*S hovmollers to accurately capture this!

 

The NH wavecycle is clearly way ahead of the SH. Note the westward retraction of the SH subsurface warmth bifurcating from the first OKW (which is already well into the EPAC) recharging that weak OKW in the WPAC, while the NH is just a massive OHC void propagating westward ahead of the initial OKW. So disorganized.

 

http://www.cpc.ncep.noaa.gov/products/GODAS/pent_gif/xy/movie.d20.gif

 

http://www.cpc.ncep.noaa.gov/products/GODAS/pent_gif/xy/movie.d20.gif

 

Something significant must have perturbed the tropical Pacific ocean circulation last winter. My guess is the SSW had something to do with it, but that’s just a guess.

 

I personally think that's exactly what happened, the SSWE likely set off the MJO pulse in February which then kickstarted the advancement towards NINO-esque conditions this year and likely triggered the first big OKW we saw this past spring.

[Phil]

Here's what the latest 45 day forecast shows, look how the trades are virtually dead in the Atlantic from mid July onward, that would favor a major, prolonged warming in the tropical Atlantic. If this verifies I'll certainly start to have faith in a head fake to warm neutral ENSO, classic late 19th-early 20th century behavior (again)... We also just completely lost whatever +PMM we had going into the summer granted it usually fades after the spring, but this doesn't help my confidence in a weak-moderate NINO this year. Really need the tropical Atlantic to stay cold to keep this solution alive...

 

http://blog.southernwx.com/wp-content/uploads/2018/07/jimcThLS.jpg

Interesting information. Does Dr. Maue have that EPS hovmoller plot available for 0-10N, by chance?

 

I’d be curious to see how far north those westerly anomalies extend across the Atlantic..since the trade wind variations that modulate the AMM seem to focus somewhat north of the equator.

[Phil]

I posted this last night in the western thread, but another factor that might play into the midsummer progression is the completion of this round of poleward +AAM propagation. Does it recycle fast enough? The previous cycle of -AAM propagation certainly affected the tropical forcing through boreal spring.

 

We were depositing easterly momentum above the zero wind line following the SSW, which along with the transitioning QBO at/below 50mb could have preconditioned the system for this recoiling vacillation.

 

 

I think the evacuation of easterlies from the tropical tropopause could (theoretically) stabilize the Walker Cell, or it could also undercut it and/or bump it eastward and allow for more WWB activity west of the dateline. Hard to know.

 

Might even depend on the state of subseasonal wave activity! So fascinating.

[Phil]

Yeah 2009 says hi, the dateline trade wind burst in July was somewhere in the ballpark of 8-10 m/s, pretty close to what's forecasted in the next week or so. It still amazes me that this year found a way to produce a borderline strong El Nino, you wouldn't know that from looking at the U850 evolution. Like this year however 2009 had a huge OKW early in the game to get it thru the summer (this year's was bigger actually) and like w/ most weak-moderate events (although it could be argued 2009-10 was strong), the trades relaxed after the September equinox and that was all she wrote. This pretty remarkable east-central Pacific trade wind burst this late in the game still would not be enough to convince me of a head fake given what happened in 2009-10. It's actually borderline scary how similar the trade wind evolution this July looks to July 2009.

Hmm..that one is interesting. Definitely had the WWB activity over the IPWP, but those are some hefty dateline trade bursts as well.

 

I wonder if, when the QBO is negative @ 50mb, the reduction in off-equator convection during the -PMM can actually aid El Niño development in some circumstances. Would definitely help keep the Pacific ITCZ/Hadley Cell retracted equatorward and stronger/tighter.

 

Could also explain why 2014 temporarily stepped back despite the favorable early season forcing, and it could also explain why 2009 went “all-in” with little push.

 

And 2012 had almost zero mechanical support, yet it nearly pulled off a canonical event. I sort of think there’s a bug hidden deep within the climatology that applies specifically to -QBO 50mb cases, as it relates to the PMM and EPAC ITCZ structure. But I’m not sure yet. Could be coincidence or something temporary and confined to recent decades only.

[Webberweather53]

You have a point re: it being difficult to avoid some type of recovery in the AMM following record lows. So I’m not going to try and claim that I was “correct” if the recovery is modest. Obviously I’m expecting something bigger, more similar to what happened in 1989. If I’m wrong I’ll be the first one to admit it.

 

And yeah, it would be interestino to repeat the “slow walk” to El Niño again, after it just happened in 2014. Might be time to consider the effects of low solar on ENSO tendencies (paleo data unanimously indicates that more frequent niños and +PDO/ weak Asian monsoons are the typical climatological responses to minimums in solar activity).

I’ve taken a deeper look into this and I am somewhat convinced the North African monsoon has a lot to do with the recent and projected slackening of the east-central Atlantic trades, we’ve observed a long term trend since the 1970s towards a wetter Africa and this year is continuing that trend. Large-scale convergence into North Africa usually means there’s anomalous westerly flow over the tropical Atlantic which shuts down the stronger easterlies we’ve observed in and immediately after winters dominated by a +NAO due in part to AGW, long term trend towards more E hem forcing, and the preceding winter ENSO (Niña)

[Phil]

I’ve taken a deeper look into this and I am somewhat convinced the North African monsoon has a lot to do with the recent and projected slackening of the east-central Atlantic trades, we’ve observed a long term trend since the 1970s towards a wetter Africa and this year is continuing that trend. Large-scale convergence into North Africa usually means there’s anomalous westerly flow over the tropical Atlantic which shuts down the stronger easterlies we’ve observed in and immediately after winters dominated by a +NAO due in part to AGW, long term trend towards more E hem forcing, and the preceding winter ENSO (Niña)

Interesting take. The presence of this +IOD cell would also lend support to the African monsoon, so you might be onto something.

[Phil]

FWIW, there are indications that the -AMO type SSTA signature has been decreasing in frequency during the summer through most of the Holocene, thanks to a strengthening LTG under declining obliquity.

 

It so happens that this is the inverse of our (ongoing) shorter term climate state (weaker LTG/+NAO/warm globe).

 

 

Which makes sense if warm periods bias towards +NAO/poleward jets during the cold season.

 

 

So the increased seasonality of the AMM is something pretty typical of warm periods. Note the early/mid Holocene behavior w/ the weaker insolation gradient (analogous to periods of weaker LTG for other reasons).

 

 

And the long term effects of the strengthening LTG through the Holocene also fits the structure for cold climate periods w/ the increased ENSO frequency and weaker Asian monsoons/smaller IPWP.

 

 

Note the transition out of the MWP/into the LIA featured a matching tendency.

 

[Phil]

Shoot, this was supposed to be the second image.

 

[Phil]

Mike Ventrice is going all-in on the ECMWF monthly depiction of an El Niño standing wave developing after this MJO passage.

 

Color me skeptical. For now.

[Phil]

The ongoing trade surge has taken a big bite out of the WPAC/Dateline SSTs.

 

This is one of the reasons I avoid relying too much on seasonal/climate modeling of tropical forcing (especially regarding low frequency transitions). They have a rough time simulating this type of air/sea interactivity on the intraseasonal scale. They don’t “see” it. All parameterized.

 

[weatherfan2012]

The ongoing trade surge has taken a big bite out of the WPAC/Dateline SSTs.

This is one of the reasons I avoid relying too much on seasonal/climate modeling of tropical forcing (especially regarding low frequency transitions). They have a rough time simulating this type of air/sea interactivity on the intraseasonal scale. They don’t “see” it. All parameterized.

The ongoing trade surge has taken a big bite out of the WPAC/Dateline SSTs.

This is one of the reasons I avoid relying too much on seasonal/climate modeling of tropical forcing (especially regarding low frequency transitions). They have a rough time simulating this type of air/sea interactivity on the intraseasonal scale. They don’t “see” it. All parameterized.

yeah I don't get the moderate El Nino talk from many this year This has a warm neuturl feel to it El Nino most likey holds off until spring summer 2019.

[Webberweather53]

A few weeks of strong easterly trades over the dateline won't kill off an El Nino but if the EPS is right, 2 months of dateline trades definitely would.

 

http://www.atmos.albany.edu/student/ventrice/real_time/timeLon/u.anom.30.5S-5N.gif

 

 

[Guest happ]

https://www.climate.gov/news-features/blogs/enso/look-south-enso-forecasters

 

[TigerWoodsLibido]

https://www.climate.gov/news-features/blogs/enso/look-south-enso-forecasters

Strong niño? Lame.

[Phil]

Modest OKW now evident in the east-central Pacific.

 

http://www.cpc.ncep.noaa.gov/products/analysis_monitoring/ocean/anim/wkxzteq_anm.gif

 

Given the timing involved here, I suspect this (along with a few other factors) precludes an “official” El Niño this year, though the system state may very well have a somewhat niño-esque flavor this fall/winter, and I still think we’ll move into a real El Niño during 2019.

[Webberweather53]

I'll give Ventrice this, there is a standing wave in the Pacific, it's just in the subtropics thanks to the +NPMM, the warmer bgd climate, etc, but it's doing no good there for this NINO. The only real cure to get this forcing back towards the equator is to wait on the seasonal cycle, that'll take until at least late September or October.

 

 

http://www.atmos.albany.edu/student/ventrice/real_time/timeLon/vp.anom.30.10N-20N.gif

[Jesse]

I'll give Ventrice this, there is a standing wave in the Pacific, it's just in the subtropics thanks to the +NPMM, the warmer bgd climate, etc, but it's doing no good there for this NINO. The only real cure to get this forcing back towards the equator is to wait on the seasonal cycle, that'll take until at least late September or October.

 

 

http://www.atmos.albany.edu/student/ventrice/real_time/timeLon/vp.anom.30.10N-20N.gif

Why do you want a niño so bad?

[Webberweather53]

Why do you want a niño so bad?

 

What are you talking about, I'm just stating facts here, there's no need to get defensive or up in arms over NINO posts.

[Jesse]

What are you talking about, I'm just stating facts here, there's no need to get defensive or up in arms over NINO posts.

It was a serious question. I thought maybe you lived in an area where niño climo favors more active winter wx.