Jump to content
  • Member Statistics

    17,586
    Total Members
    7,904
    Most Online
    23Yankee
    Newest Member
    23Yankee
    Joined

ENSO Thread 2011


Recommended Posts

Wouldn't it still reflect the overall "nina signal" in being there? I'm not knowledgable here, just think the globe looks somewhat Nina.

Not really. The SOI was being overwhelmed by the TC signal. No doubt it's mostly Nina right now, but AAM anomalies went >0 last week for the first time in 8 mos, so the Nina isn't as strong in the atmosphere as we had seen.

Link to comment
Share on other sites

Yeah just to throw out some stats which most people are already pretty familiar with:

Since 1950 there are 5 cases of a moderate Nino or stronger transitioning to a moderate Nina or stronger (63-65, 72-74, 87-89, 97-99, 06-08).

In only 1 of these cases was the Nina followed by a Nino event. (63-65 was followed by the 65-66 Nino).

63-64 was a boderline weak El Niño...it only had 2 trimonthlies at 1.0C and most of the others were like 0.8C, so some people consider it weak. The pattern in the US was certainly very typical of weak.

64-65 was also a bit weaker of a Niña than the other ones being discussed (73-74, 88-89, 98-99)...so it had more room to go back to El Niño.

Link to comment
Share on other sites

63-64 was a boderline weak El Niño...it only had 2 trimonthlies at 1.0C and most of the others were like 0.8C, so some people consider it weak. The pattern in the US was certainly very typical of weak.

64-65 was also a bit weaker of a Niña than the other ones being discussed (73-74, 88-89, 98-99)...so it had more room to go back to El Niño.

Yes I mentioned later in the post that the 64-65 Nina had already subsided by this point giving it more "room" to transition to Nino.

As I noted, no moderate Nino has developed with a preceding JFM ONI of -1C or colder. Only 1 weak Nino has developed with a JFM of lower than -.9C (76-77). To go to a Nino from our current -1.2 JFM ONI would be nearly unprecedented. There are 9 cases of a JFM of -1C or colder, only 1 transitioned to a Nino and it was a weak one.

Link to comment
Share on other sites

Statistically, it's definitely least likely following a moderate/strong Nina, especially a first year one. The fact we are in a -PDO phase weighs further against a Nino.

Sure. Of course we can clearly see the stats do not favor a nino, and I'm definitely not saying I "favor" it either, but there are some unique characteristics of this event that make it trickier, so I'd make sure all options are on the table.

Link to comment
Share on other sites

What does this mean? Can you explain the diagrams?

Low Angular Momentem is when the Jet/ westerlies are further north. High AAM is when the Jet/Westerlies are further south. Frictional Torque and Montian Torque are self explainatory. I have no idea what coriolis torque is and how it would transfer momentum from the atmosphere to the earth.

gwo_phase_fig4.jpg

Link to comment
Share on other sites

Not really. The SOI was being overwhelmed by the TC signal. No doubt it's mostly Nina right now, but AAM anomalies went >0 last week for the first time in 8 mos, so the Nina isn't as strong in the atmosphere as we had seen.

The AAM anomalies are due to the MJO, i think. We haven't had one that well-defined in quite some time. The anomalies are crashing hard again this week so I think it was just a blip upward....

Link to comment
Share on other sites

Low Angular Momentem is when the Jet/ westerlies are further north. High AAM is when the Jet/Westerlies are further south. Frictional Torque and Montian Torque are self explainatory. I have no idea what coriolis torque is and how it would transfer momentum from the atmosphere to the earth.

Could be BSing this ... the Coriolis torque is a product of the Coriolis force acting to the right of the meridional wind. So net poleward flow produces a positive torque, and net equatorward flow produces a negative torque. If this is the case, it must be a product of the ageostrophic wind (since in geostrophic flow there is no net poleward component), which is usually directed from higher to lower pressures. So if we roll with that idea, the Coriolis torque is a product of the Hadley circulation, which is related to tropical convection and the annular mode. In a high index state, we see a stronger Hadley circulation with net poleward flow and a positive torque. In a low index state (high latitude blocking situation), we see a weakened Hadley circulation with net equatorward flow and a negative torque.

Right now, we've seen a strong negative AAO develop in the last week, which may correspond to the negative Coriolis torque we see centered around 50S.

We're seeing a combination of forces right now with this large negative tendency. We have seen a decent North American mountain torque in the last week, superimposed on a negative friction torque, and this negative coriolis torque. The mountain torque, centered near 50N is most certainly a product of the digging trough out west. In addition, this trough has acted to transport higher momentum air poleward, lifting the zonal flow we had across the northern tier of the US last week, north into Canada. In accordance, we're also about to see a nice spike in the NAO.

Link to comment
Share on other sites

  • 4 weeks later...

Are some people wishcasting a Niño? Aren't Niñas usually multi-year rather than 10 month events?

No they weaken to neutral a lot of times for the next year.

The warm SSTs lurking below the surface likely rules out anything more than a weak nina next year.

Link to comment
Share on other sites

the oni index for FMA was -0.9...This is a list of years with a minus oni for FMA and what it was the following NDJ...

year.....FMA.....NDJ...

1950.....-1.3.....-1.0

1951.....-0.6......0.6

1955.....-0.9.....-1.9

1956.....-0.7.....-0.8

1968.....-0.8......0.9

1971.....-1.1.....-0.7

1974.....-1.3.....-0.7

1975.....-0.7.....-1.7

1976.....-0.8......0.7

1985.....-0.7.....-0.4

1989.....-1.1.....-0.1

1996.....-0.5.....-0.4

1999.....-0.9.....-1.6

2000.....-1.0.....-0.7

2001.....-0.4.....-0.1

2008.....-1.1.....-0.6

2011.....-0.9.....?????

Link to comment
Share on other sites

the oni index for FMA was -0.9...This is a list of years with a minus oni for FMA and what it was the following NDJ...

year.....FMA.....NDJ...

1950.....-1.3.....-1.0

1951.....-0.6......0.6

1955.....-0.9.....-1.9

1956.....-0.7.....-0.8

1968.....-0.8......0.9

1971.....-1.1.....-0.7

1974.....-1.3.....-0.7

1975.....-0.7.....-1.7

1976.....-0.8......0.7

1985.....-0.7.....-0.4

1989.....-1.1.....-0.1

1996.....-0.5.....-0.4

1999.....-0.9.....-1.6

2000.....-1.0.....-0.7

2001.....-0.4.....-0.1

2008.....-1.1.....-0.6

2011.....-0.9.....?????

Yea it still looks like climo is quite against a resurgence in El Nino. While the animation of the sub-surface temperatures above is interesting as Nino 1+2 seem to be warming, also noted in the last few frames is another area located over near Nino 3.4 that no longer has any subsurface positive anomalies between 140-180 degrees west. If we are going to see a full blown El Nino, I think we are gonna need to see a more substantial WWB that propagates further eastward. If you guys can recall for the 09-10 El Nino, the wheels were in motion already by this point. The image below, however, doesn't really scream a major pattern shift in wind anomolies.

34j7jwk.gif

Link to comment
Share on other sites

Although I pointed out earlier in this thread from a statistical ONI perspective, neutral neg, or weak Nina seems most likely, OHC is substantially higher than most Ninas including 2nd year ones. So we have conflicting signals.

Over the past few weeks the CFS forecast has steadily risen about .4C and now shows peaking in the weak Nino category. The CFSv2 almost makes it but then drops back neutral neg. Personally I think the CFSv2 looks pretty realistic.

PDFcr_nino34SSTMon.gif

nino34Mon.gif

Link to comment
Share on other sites

Although I pointed out earlier in this thread from a statistical ONI perspective, neutral neg, or weak Nina seems most likely, OHC is substantially higher than most Ninas including 2nd year ones. So we have conflicting signals.

Yeah the OHC is what makes it interesting, especially with this big MJO jolt into p7-p8 and the massive AAM spike that is underway. Stats definitely favor a dip back into Nina this coming fall / winter, but in looking at the OHC, this April's values are higher than they were in the April of every year that saw a Nino develop (since 1980) except for the two super ninos.

Link to comment
Share on other sites

Although I pointed out earlier in this thread from a statistical ONI perspective, neutral neg, or weak Nina seems most likely, OHC is substantially higher than most Ninas including 2nd year ones. So we have conflicting signals.

Over the past few weeks the CFS forecast has steadily risen about .4C and now shows peaking in the weak Nino category. The CFSv2 almost makes it but then drops back neutral neg. Personally I think the CFSv2 looks pretty realistic.

PDFcr_nino34SSTMon.gif

nino34Mon.gif

Looks like latest runs have trended colder again.

Link to comment
Share on other sites

  • 2 weeks later...

BOM calls time of death

The 2010−11 La Niña event has ended, with climate indicators of the El Niño - Southern Oscillation (ENSO) having returned to average levels. Climate models surveyed by the Bureau of Meteorology suggest that the Pacific Ocean will continue to warm over the coming months, with neutral conditions likely to persist through the austral winter; that is, neither La Niña nor El Niño.
Link to comment
Share on other sites

Every other Nina event that died by May/June was not followed by another Nina the following winter. Since very few first year Ninas have been followed by Ninos, I would say the odds strongly favor neutral ENSO next winter.

I agree... I'd say neutral next winter and an el nino the winter after that based on prior analogs. Neutral after la nina winters usually suck for us (89-90, 01-02).

Link to comment
Share on other sites

Archived

This topic is now archived and is closed to further replies.

  • Recently Browsing   0 members

    • No registered users viewing this page.
×
×
  • Create New...