Has the NINA Peaked?

[nzucker]

There were more interruptions with weaker trade winds over ENSO regions during June and July than in September. From the chart I am looking at I would rate August and October as the two months with the strongest most persistent trade winds, followed by September, then June and July. Probably the biggest burst occurred in late August and carried over into the first couple days of September.

Yes, and there was a massive amount of cooling from August 26th to September 6th using the NOAA maps, mostly in the eastern regions.

[skierinvermont]

No I am not...stop arguing with me just for the sake of it.

If the +AAM causes westerly wind bursts to interrupt the trades, that is a mechanism in and of itself. Even if the trades are strong, a few days of westerly winds bringing warm waters from the high SST pool near Indonesia can disrupt the event. We have had two periods of strong MJO bursts/+AAM since mid-October, and that's why it's not cooling more. Period.

Then you would expect the trade winds to be less persistent and not as strong.. and I keep telling you we had strong persistent trade winds in October.

I am not arguing with you for the sake of arguing with you .. I am disagreeing with you because you are not making sense.

[nzucker]

Then you would expect the trade winds to be less persistent and not as strong.. and I keep telling you we had strong persistent trade winds in October.

I am not arguing with you for the sake of arguing with you .. I am disagreeing with you because you are not making sense.

I am not disagreeing with the fact that we had strong persistent trades...but we also had two big MJO bursts and +AAM episodes. AAM was lower during the summer so the westerlies were more subdued.

You haven't proposed any mechanism to explain the lack of cooling. I have..

[skierinvermont]

I am not disagreeing with the fact that we had strong persistent trades...but we also had two big MJO bursts and +AAM episodes. AAM was lower during the summer so the westerlies were more subdued.

You haven't proposed any mechanism to explain the lack of cooling. I have..

Except your mechanism doesn't make sense. There were more westerlies over ENSO regions during the summer than during October. I've said this about 8 times now. The westerlies were NOT "more subdued because of the -AAM in summer." We had strong persistent easterly winds over ENSO during October relative to the other months of this Nina.

[nzucker]

Except your mechanism doesn't make sense. There were more westerlies over ENSO regions during the summer than during October. I've said this about 8 times now. The westerlies were NOT "more subdued because of the -AAM in summer." We had strong persistent easterly winds over ENSO during October relative to the other months of this Nina.

Well, there maybe there are aspects of the AAM we don't understand. I didn't say the trade winds were the only effect...it could have to do with the feeding in of colder waters through modulation of the Humboldt/Chilean current. I don't know enough about the AAM to say.

I just know that -AAM correlated with a cooling this summer...when the AAM went positive in the mid-fall, which is more typical of El Niño, we lost the cooling. Now that it's coming back negative, it should cool more. Unisys maps confirm this is happening.

[skierinvermont]

Well, there maybe there are aspects of the AAM we don't understand. I didn't say the trade winds were the only effect...it could have to do with the feeding in of colder waters through modulation of the Humboldt/Chilean current. I don't know enough about the AAM to say.

I just know that -AAM correlated with a cooling this summer...when the AAM went positive in the mid-fall, which is more typical of El Niño, we lost the cooling. Now that it's coming back negative, it should cool more. Unisys maps confirm this is happening.

Yes some mechanism whereby the AAM affects something other than 850mb trade winds could make sense.

Mostly I think it's just that the Nina is already so strong it is hard for it to strengthen more. it's also more west based than some other strong Ninas for some reason. Also possibly (A)GW is making it harder to get to super strong Nina levels.

[CoastalWx]

Yes some mechanism whereby the AAM affects something other than 850mb trade winds could make sense.

Mostly I think it's just that the Nina is already so strong it is hard for it to strengthen more. it's also more west based than some other strong Ninas for some reason. Also possibly (A)GW is making it harder to get to super strong Nina levels.

I wouldn't bring AGW into this. That's like the crazies saying AGW caused Katrina.

[skierinvermont]

Compare to November 1988 for example... clearly our current Nina doesn't look at all like it in terms of structure. While we keep mixing in warm eddies from central America.. 1988 had a huge intense cold pool there. You can see the warm eddies progress westward in our current Nina into region 3.4 over the last few months. I'd say the reason our Nina isn't making it to super strong (yet) is related to that warm pool.. so if you can explain why we have a warm pool there instead of a cool pool maybe we have our answer.

'98-99 and '99-00 and '07-08 also all had central American warm pools. '98-99 even had a warm pool south of region 3. Can't find '73-74 but I'm guessing it didn't have a warm pool.

[skierinvermont]

I wouldn't bring AGW into this. That's like the crazies saying AGW caused Katrina.

That's what the parentheses were for.. clearly the oceans and atmosphere are much warmer than they were 30 years ago. Logically this must moderate our Ninas to some small degree..

[CoastalWx]

That's what the parentheses were for.. clearly the oceans and atmosphere are much warmer than they were 30 years ago. Logically this must moderate our Ninas to some small degree..

Eh..I see what your saying, but it's all relative as well. If we have warmer water, than we have a warmer atmosphere. The physical repercussions of a wide body of -2C water would probably have a similar outcome than say 30-40 years ago. Anyways, enough climate change for me.

[skierinvermont]

Eh..I see what your saying, but it's all relative as well. If we have warmer water, than we have a warmer atmosphere. The physical repercussions of a wide body of -2C water would probably have a similar outcome than say 30-40 years ago. Anyways, enough climate change for me.

Oh yes.. and besides we're talking about a small difference of a couple tenths at most which hardly matters anyways.

I'm just trying to figure out what's different between this Nina and '88-89 and '73-74 which were much colder by late October and November.

[CoastalWx]

Oh yes.. and besides we're talking about a small difference of a couple tenths at most which hardly matters anyways.

I'm just trying to figure out what's different between this Nina and '88-89 and '72-73 which were much colder by late October and November.

Well the PDO was more negative in '72-'73.

[KEITH L.I]

Oh yes.. and besides we're talking about a small difference of a couple tenths at most which hardly matters anyways.

I'm just trying to figure out what's different between this Nina and '88-89 and '72-73 which were much colder by late October and November.

72-73 was a strong nino..maybe you were thinking about 73-74 which was a strong nina

[skierinvermont]

72-73 was a strong nino..maybe you were thinking about 73-74 which was a strong nina

yes thank you

[KEITH L.I]

yes thank you

rooting for more of a 73-74 year than 88-89..73-74 was a pretty good winter in the NYC metro

[CoastalWx]

yes thank you

LOL, well it's still embedded in a -PDO regime, and was more negative than '88-'89. Clearly not the only reason it was different, but it does stand out.

[usedtobe]

Here's another graphic showing the 850 wind anomalies. You can pretty clearly see the impact of the mjo that nzucker was talking about. It was associated with a pretty strong westerly wind burst. I'm not sure why this graphic and the one shown by Mitchnick are so different (at least to me) but it argues that there should have been warming or at least no additional cooling. Even before that burst, the easterly anomalies were not a strong as earlier in the year. Also, if you look at the graphic you'll see blue (easterlies) showing up to towards the bottom of the graphic, each time something like that has shown up earlier in the year, the easterlies have strengthened and shifted east where they would tend to produce upwelling.

[VAwxman]

I'm not sure why this graphic and the one shown by Mitchnick are so different

If I recall, the graphic you posted is based on MJO reconstruction, meaning the ENSO signal is removed, which I know is how the wheeler plot is derived (they also show one in which the ENSO signal is retained on their site, which to no surprise doesn't show the MJO anywhere near p7-p8). The graphic Mitch posted is just the raw zonal wind anomalies. So there will always be differences because one has the ENSO signal removed.

[usedtobe]

If I recall, the graphic you posted is based on MJO reconstruction, meaning the ENSO signal is removed, which I know is how the wheeler plot is derived (they also show one in which the ENSO signal is retained on their site, which to no surprise doesn't show the MJO anywhere near p7-p8). The graphic Mitch posted is just the raw zonal wind anomalies. So there will always be differences because one has the ENSO signal removed.

Then his is probably better.

[VAwxman]

Then his is probably better.

I know Ed Berry liked using the one without the ENSO signal removed, but I guess there is some value in looking at the one with ENSO removed too since maybe it is easier to see when the MJO is working against the overall ENSO state and when it is working with it. I dunno. Just figuring that there must be some logical reason why they have all these graphics with the ENSO signal removed.

[skierinvermont]

I was using the one in the weekly CPC summary that is raw and for 5N -5S vs ENSO signal removed 7.5N-7.5S.

But correct me if I'm wrong.. the MJO-induced bursts are only making it up to Indonesia.. they aren't advancing over the Pacific waters. I was only looking at wind anomalies for 180W-120W over the western and central Pacific.

[tacoman25]

rooting for more of a 73-74 year than 88-89..73-74 was a pretty good winter in the NYC metro

Not that it necessarily means a TON, but this fall is looking more similar to 1973 than 1988.

[tacoman25]

That's what the parentheses were for.. clearly the oceans and atmosphere are much warmer than they were 30 years ago. Logically this must moderate our Ninas to some small degree..

Yeah, but using the same logic, far western ENSO regions are running colder than most Ninas....AGW?

Anyway, I think MEI is a better indicator of ENSO influence on the atmosphere and consequential weather patterns.

[nzucker]

Yes some mechanism whereby the AAM affects something other than 850mb trade winds could make sense.

Mostly I think it's just that the Nina is already so strong it is hard for it to strengthen more. it's also more west based than some other strong Ninas for some reason. Also possibly (A)GW is making it harder to get to super strong Nina levels.

We've been mostly looking at 850mb wind anomalies; to discuss short-term changes, it might be more instructive to look at surface wind anomalies since these might explain the specific variations better as opposed to the overall pattern.

Compare to November 1988 for example... clearly our current Nina doesn't look at all like it in terms of structure. While we keep mixing in warm eddies from central America.. 1988 had a huge intense cold pool there. You can see the warm eddies progress westward in our current Nina into region 3.4 over the last few months. I'd say the reason our Nina isn't making it to super strong (yet) is related to that warm pool.. so if you can explain why we have a warm pool there instead of a cool pool maybe we have our answer.

'98-99 and '99-00 and '07-08 also all had central American warm pools. '98-99 even had a warm pool south of region 3. Can't find '73-74 but I'm guessing it didn't have a warm pool.

Yes, I agree the effect of the Central American warm pool has been damaging the La Niña's chance to attain record status. The latest NOAA SST map, released 11/15, shows that the warm pool has been mostly eliminated in the past couple of weeks; Unisys confirms this and shows that a huge area of cold waters has just now upwelled near Guatemala, with anomalies of -3.22C in the heart of the upwelling region. Perhaps this will get us going?

[skierinvermont]

Yeah but it's still nothing compared to 1988.. plenty of warm water still around while 1988 was just a huge cold pool everywhere. It's eroded some but still a substantial warm pool unlike '88. Wish there was data for '73-'74 to see if it was like '88-89 too.

[OKpowdah]

Pretty big build up of high OHC anomalies toward Indonesia in the last few weeks

[nzucker]

Yeah but it's still nothing compared to 1988.. plenty of warm water still around while 1988 was just a huge cold pool everywhere. It's eroded some but still a substantial warm pool unlike '88. Wish there was data for '73-'74 to see if it was like '88-89 too.

1988 was pretty insane...ridiculous cold pool near Central America and towards the eastern regions. I wonder if the current development of the cold pool in Central America, whose dominance will probably be complete in a couple weeks if you believe Unisys maps that show the maximum negative anomaly is increasing by around .1C per day, will help this La Niña along. Everything depends on if that cold pool's development gets a while to build in westward before the peak. The pattern looks favorable for a while as SOI has jumped back to the extreme values we saw this summer with strong trade winds building around 160E and then spreading into the heart of the ENSO regions.

Global temperatures have also fallen significantly if AMSU Channel 5 is to be believed...

[gil888]

There has been a waning of the trades during the past week or so which has led to some warming (I think it is mostly associated with weak MJO variability, heading into RMM phase 1). The location of the trade wind anomalies, which have generally been west of average for a La Nina, may also be relevant information. After looking at this for a while, I would have expected further cooling, but something is going on in the thermocline to repel that. Perhaps the brief weakening in mid-October also caused a brief ripple along the thermocline that is manifesting now, because animations clearly show warmer waters heading eastward at the near-surface, despite the trades.

The other way that a Nina can be temporarily held back is if warmer waters from off-equatorial regions get mixed into the equatorial regions-- which happens with the westward-moving waves that develop in La Nina events.

Of course, all that being said, I don't really understand it. We will see how the next round of trades affects things-- it should be a significant burst, and could be longer-lasting than the last few because the "MJO" should be emerging into the Indian Ocean at about the time the trades are intensifying on their own (linked events but somewhat independent)-- so there will be an additive effect there. If things get stuck in the Indian Ocean region, then that could prolong things a bit.

A break isn't unprecedented for the strong La Ninas-- 1975 had warming in Nino 3-4 during November, then rebounded in December-- so I wouldn't call this Nina dead just yet.

[usedtobe]

There has been a waning of the trades during the past week or so which has led to some warming (I think it is mostly associated with weak MJO variability, heading into RMM phase 1). The location of the trade wind anomalies, which have generally been west of average for a La Nina, may also be relevant information. After looking at this for a while, I would have expected further cooling, but something is going on in the thermocline to repel that. Perhaps the brief weakening in mid-October also caused a brief ripple along the thermocline that is manifesting now, because animations clearly show warmer waters heading eastward at the near-surface, despite the trades.

The other way that a Nina can be temporarily held back is if warmer waters from off-equatorial regions get mixed into the equatorial regions-- which happens with the westward-moving waves that develop in La Nina events.

Of course, all that being said, I don't really understand it. We will see how the next round of trades affects things-- it should be a significant burst, and could be longer-lasting than the last few because the "MJO" should be emerging into the Indian Ocean at about the time the trades are intensifying on their own (linked events but somewhat independent)-- so there will be an additive effect there. If things get stuck in the Indian Ocean region, then that could prolong things a bit.

A break isn't unprecedented for the strong La Ninas-- 1975 had warming in Nino 3-4 during November, then rebounded in December-- so I wouldn't call this Nina dead just yet.

Good post. I feel the same way but also think what you say makes sense.

[Gastonwxman]

Yes, I agree the effect of the Central American warm pool has been damaging the La Niña's chance to attain record status. The latest NOAA SST map, released 11/15, shows that the warm pool has been mostly eliminated in the past couple of weeks; Unisys confirms this and shows that a huge area of cold waters has just now upwelled near Guatemala, with anomalies of -3.22C in the heart of the upwelling region. Perhaps this will get us going?

Today's map shows quite a difference in Nino regions 3 and far eastern section of 3.4, although this could be just one of those fluctuations that we normally see, so I don't know what to make of it.