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2014 ENSO Mega Thread


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Nino 3.4 is going to have trouble pushing much beyond borderline weak El Nino

levels since the EQ. upper-ocean heat anomalies have declined slightly over the

last week. Maybe we can bump up to 0.5-0.6 range on official CPC weeklies before 

leveling of again. The stronger trades at 150E to 180 are currently pushing back against 

much significant warming.

 

bluewave - it looks to me like warm anomalies are continuing to be supplied at depth west of the dateline.  With that chart showing upper ocean content east of the dateline, I wouldn't be surprised to see the values remain elevated above normal as the warm anomalies continue to push east, but we'll see.  No doubt though that the wind anomalies haven't been Nino-like this year (neither has the OLR pattern).

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Fascinating read Mike.  Thank you for posting.  What you say makes sense.  Would you agree with the potential for a negative AO this winter as a base signal?  If so, then combined with your ENSO signal, would you agree that the tendency will be to have a stormier and more up and down winter averaging near or slightly above zero on temp anomaly, but slightly wetter as well??

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It looks like a warmer winter is at hand. This could induce more precipitation concentrated storms to emerge from the SW US or GOM. If the AO is persistently negative, then we could see cold overrunning events.
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An email sent out by Dr. Paul Roundy from the University at Albany:

 

All--Sorry for double posts. I don't have enough time to cover many of the details, but intraseasonal conditions, including a recent west Pacific westerly wind burst and interaction between the tropical and extratropical circulations and eastward radiation of atmospheric Kelvin waves over the Western Hemisphere have initiated a collapse in the east central Pacific equatorial easterlies: 

http://manati.star.nesdis.noaa.gov/datasets/ASCATData.php/

http://www.atmos.albany.edu/student/carl/weather/timeLon/u.total.30.5S-5N.png

The recent westerly wind burst west of the dateline and the collapse of the equatorial easterly wind support further growth of SST anomalies toward El Niño conditions in a large scale pattern similar in some respects to conditions of northern fall 1986. 

Equatorial east Pacific warmth is already in place (and has been for a few months):

http://www.esrl.noaa.gov/psd/map/images/sst/sst.daily.anom.gif

 

The CFS V2 suggests that these signals mark development of coupling between atmospheric convection and SST anomalies:

http://www.atmos.albany.edu/student/macritch/realtime/sst/075N_2_5.png

http://www.atmos.albany.edu/student/macritch/realtime/filteredhovs/075N_6_5.png

http://www.atmos.albany.edu/student/macritch/realtime/filteredhovs/075N_6_5_uwnd850.png

everything after the horizontal black line is a 4-member ensemble mean forecast. Note that CFS does seem to have a bias toward producing such coupled outcomes in base state conditions that are not quite suitable to such outcomes in nature, but it does support the view that the developing El Niño event is not diminishing as some have suggested because of its apparent timing late in the seasonal cycle. Also, the CFS has a slow phase speed bias in propagating such coupled signals eastward. Another consequence of these intraseasonal signals is that the MJO appears to be becoming better organized, thereby setting the stage for potentially intense central Pacific westerly wind bursts in November. 

 

Best wishes--

Paul Roundy

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Definitely going to be some warming over the East Central equatorial Pacific.

 

 

 

u_zps5b3e8038.png?t=1413098430

That should at least help push some of the surfacing cooler water back west that has been infiltrating the current surfacing Kelvin Wave .  If they were a bit further west, it would really help in the Kelvin Wave generation area.  

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The current lack of a strong WWB pattern over the key 140E to 180 region will keep

the Nino 3.4 temperatures treading water around boderline weak El Nino thresholds.

Notice how the trade winds are dominating that zone of the Western Pacific

where strong WWBs occurred in recent El Nino Octobers of 2002,2004,2006, and 2009.

It looks like the added warmth of the WPAC this October compared to 2002,2004,2006, and 2009

is limiting the top end development potential as it favors stronger trade winds.

 

October 2014 so far

 

attachicon.gif14.gif

 

October El Nino composite

 

attachicon.gifcomp.png

 

Warmer WPAC

 

attachicon.gifSST.gif

 

While the first half of October were associated with enhanced trade flow, it will mainly the result of the intraseasonal state. This state has flipped in accordance of the MJO pushing across the Western Hemipshere:

 

twc_globe_mjo_vp200.png

 

The 7-Day GFS op forecast is calling for strong westerly wind anomalies to develop o/ the Date Line, and later over the East Pacific. I suspect if you average the second half of October, you will see a composite map similar to what you shown.

 

u.anom.30.5S-5N.gif

 

Note that ENSO events occur on a spectrum and thus are not all the same. I'm not sure cherry picking a number of years where the ENSO criteria threshold was met in a particular month is the best way to go. That being said, I'm not sure what the best way is to compare other than this methodology. 

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Nino 3.4 looks a little better.  Filling in a little more with the positive anomalies.  

 

 

 

It does but still mostly sideways in the area for an extended period. Maybe we get a break our way with the forecast trades. Gotta get something sustained going for us. It may not matter in the end and we are just nitpicking #'s. I'm not sure how much different eeking into official nino vs just a warm neutral makes at this point. 

 

PDO region is looking great. That's definitely a good thing as we close in on met winter. We've been in a + state for 8 months and Oct surely looks to continue that so 9 is in the bag. The last time we had a +pdo for that long started in Sept of 02 and continued for the next 26 months. Brief drop to neg in Oct-Dec 04 but went back + after that. A 37 month stretch with only 3 months negative. 

 

It's pretty remarkable how similar the state of the npac as a whole looks to this same time in 03.

 

anomnight.10.11.2003.gif

 

 

 

We'll have to see how the GOA looks in 2 weeks. It's going to be close to breaking the back on the warm anomalies. Ensemble guidance across the board shows low heights and temps in that region for an extended period. 

 

IMO- it's hard to ignore the 02-05 period for clues. Something in between those 3 winters seems possible and reasonable. 

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Westerlies had been developing and they're forecasted to continue.  This would be good fore helping the current Kelvin wave, which appears to be surfacing currently.  Although the Kelvin wave doesn't appear to be nearly the strength of the one back in April, it should be enough to spur at least a weak Nino.  

 

weeks1to2.png   wkteq_xz.gif

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                      Nino1+2      Nino3        Nino34        Nino4
 Week             SST SSTA   SST SSTA   SST SSTA   SST SSTA
 03SEP2014     21.7 1.2     25.3 0.4     27.1 0.4     29.2 0.5
 10SEP2014     21.1 0.7     25.3 0.4     27.3 0.5     29.4 0.7
 17SEP2014     21.0 0.7     25.2 0.4     27.2 0.5     29.4 0.8
 24SEP2014     21.2 0.8     25.4 0.5     27.1 0.4     29.3 0.6
 01OCT2014     21.7 1.1     25.4 0.5     27.1 0.3     29.2 0.5
 08OCT2014     21.3 0.6     25.5 0.6     27.1 0.4     29.1 0.5

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The Euro is suggesting that -SOI's will be predominant over the next 9 days though they shouldn't be really strong negatives for the most part...just mainly weak to moderate. This will probably tilt October as a whole to the negative side, which would mean still another -SOI month.

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 Things are looking up for a weak to low end moderate Nino to verify:

 

1) Recent SOI's have been solidly negative (four days in a row of -10 or lower), which is the first time for that kind of thing in three weeks. The Euro suggests that the next week or so will be dominated by negatives (say mainly -5 to -20). This is enough to tell me that a final Oct SOI of, say, -4 or more negative is likely. That would make it the 5th -SOI month in a row, which is a rather sig. indicator for the start of El Nino based on 135+ years of data.

 

2) The Cowan graph shows 3.4 to be at +0.619, which is a rise of ~0.3 in its the last three days and brings it warmer than it was when that spike maximized a month ago. It is at its warmest of the last 3+ months. Oct. as a whole has a chance to end up near or above +0.5 in the monthlies.

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Latest IRI update for October keeps things on a general sideways weak track going forward.

 

Average, dynamical models 0.6 0.6 0.7 0.7 0.7 0.7 0.7 0.6 0.5

 

The peak for the statistical models moved up a tenth and the peak for the dynamical models moved down a tenth.  Very good agreement now on a low end weak el nino for fall/winter ONI

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After all the models showing steeper increases for months failed and now flatlining, it would be ironic to get unexpected perfect conditions for a spike over 1.0. Not saying I think that will happen. It would just be fitting after what's transpired since spring. 

I believe that the Albany group is working on ENSO forecasts based on the state/location of Oceanic Kelvin waves. Should be fascinating to see the results.. I presume the climate model forecast is sensitive to the location of an oceanic Kelvin wave, which will cause the model to miss the intraseasonal variability in the Pacific.

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Regarding the 500 mb height anomaly map of 10/1-14 posted above by Bluewave, it is interesting that along the southern and eastern fringe of that strong e us negative anomaly that the temp.'s were well above normal including about ~90th percentile warmth since 1930 at Atlanta. Actually, much of the E half of the US outside a chunk of the Midwest was warm even though you'd never suspect that based on this negative 500 mb height anomaly that dominates.

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Per TAO, there is a significant WWB along with rather sharp warming now in western 3.4.

 

TAO 5 day mean now up to near +0.7 fwiw. Cowan pretty steady just below +0.6 (+0.572). It will be interesting to se if NOAA will release a warmer weekly tomorrow vs. last week's release of +0.4.

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