Friday, May 29, 2009

Postponed

The views expressed are those of the author and do not necessarily represent those of the National Weather Service.”

As I typed on 23 May, I will not be able to do my next discussion until the weekend of 5-7 June. In general, postings will be difficult this summer due to travel, covering shifts, etc.. This is all the more reason why our effort needs to be mainstreamed asap. Please email me/leave comments if you have questions.

Please see links in the 23 May discussion for real-time and other information. An apparently rapid GWO 7-8-1 transition is occurring as I type, and zonal mean westerly wind flow anomalies are strong in the subtropical atmospheres (~plus 5-7m/s at ~15N/250mb). Loosely, a superposition of phase 5 for the MJO and phases 8-1 of the GWO 250mb snr psi composite anomaly plots depicts the current global circulation. I think the wind and convective signals getting back into sync. That coupling is probable to occur in the region of the west Pacific Ocean during the next few weeks, projecting in octants 6-8 of MJO/GWO phase space, which is on the El-Nino side. Having the expected difficulties, most models are starting to capture a USA synoptic evolution days 5-10 fairly consistent with the atmosphere heading toward these GWO/MJO phases.

As the subtropical westerly wind flow anomalies propagate poleward, relative to climatology the North Pacific Ocean jet will strengthen. Perhaps as part of a more robust coupled GWO/MJO 7-8-1 transition, at some point this jet is likely to come into the western states while collapsing, leaving a trough in its wake. This could lead to a very active southwest flow storm track focusing on the central/northern Plains/Upper Mississippi Valley regions ~mid June. Weather impacts, as well as all the issues with unpredictable timing and other details, are understood.

As compared to a year ago, I am now convinced that some form of an El-Nino is more probable going into the 2009-10 boreal cold season. However, the issues raised in past discussions remain valid, and we need to diligently and rigorously monitor. Will the tropical convective forcing signal finally "get out of Dodge (La-Nina)" and start hanging out in the west Pacific beginning this summer? That is, in contrast to the past 2 Northern Hemisphere cold seasons, be displaced toward octants 6-8 of WH (2004) phase space? Stay tuned.

Ed Berry

8 comments:

snoman said...

Hi Ed,

I was just about to "bite off" on an El Nino developing, but the equatorial Pacific surface pressure anomalies have taken a decided return to a La Nina configuration the past few days. Very notably a strong positive anomaly has set up off the southern West Coast of South America sloping to strong negative anomlies over the Western Pacific. On the other hand, given the warm subsurface ocean temperatures across the equatorial Pacific at least a brief venture into above normal Nino SST's does seem pretty likely. The big question is whether that will lead to a full blown Nino or not. Two indices that normally foreshadow El Nino have yet to indicate such an event, those being the NOI and SOI* (different than the SOI). This will be interesting to watch!

Another issue that remains to be seen is whether the atmosphere during the winter will react in a typical manner to any oceanic El Nino that may develop. There are those oddball El Nino / negative PDO winters that happen from time to time.

I hope you are able to do at least some complete posts over the course of the summer.

Jim

Captain Climate said...

Hello Ed;

Thanks for providing the brief update this morning despite your stated intention to take a break. The loop in the MJO implying a close repetition of the weather pattern would be an opportune time.

It is difficult to swallow, at this juncture, a commencement of a winter El Nino on the basis of the present overall weather situation.

BUT .... If I were one wanting an exciting US Eastern Winter then contrary to last year when the mainstream was calling for El Nino (from the tops of mountains!)the less than ideal setup right now could be viewed in a positive light. El Nino's which fire up in the summer and fade from fall through winter CANNOT BE TRUSTED (example: 2006-07).

A comparison of SOI variables between last year and this one are similar ... BUT the MJO seems to be singing a much different tune.

The AAM breakout we have been waiting for??? I will definitely stay tuned...

Thanks for your hard work and generosity to share.

Dean

snoman said...

Dean,

I just have to comment on a couple of the things you pointed out. First of all the possible AAM
breakout we have seen may be short lived as the tendency is showing one of the sharpest declines in months.

There is no question the MJO will be interesting to watch. At present it is pretty much dead, but as we all know it could come back at any time. If the MJO stays inactive or over the Indian Ocean the El Nino is pretty much DOA.

You make an interesting point about the 2006-07 El Nino. At this point cold winter fans from pretty much any part of the country should be very cautious about getting too excited or concerned at this point.

Jim

Ed Berry said...

All,

Thank you for the comments and interactions! I just made a few edits.

Believe me,the winter of 2006-07 is one of our best cases when important subseasonal activity not only shut down El-Nino, but likely initiated the cold event. We were cautioning others about those issues at that time. Right now it is a monitoring game. The odds have hedged a bit toward a warm event; however, we will see what happens this fall.

Ed

Captain Climate said...

Hello Snoman;

My "possible AAM breakout" comment was not intended to be taken in anticipation of a Bull AAM run. I really agree with you right now regarding skepticism about an upcoming El Nino. See my quote below:

"It is difficult to swallow, at this juncture, a commencement of a winter El Nino on the basis of the present overall weather situation."

My opinion is ... IF an El Nino got rolling right now then it would roll over into its grave by or through winter.

Could the dead MJO and some rumblings under the surface ... per se ... be a contrarian argument for a firing up of a higher AAM event later in 2009?
The Atlantic seems to be losing its steam with the collapse of the AMO and recovery to only neutral.
A drier Africa (Sahael) is also a variable to consider re: whether a fundamental change is in process.

I am becoming increasingly concerned that the longer the climate is trapped in a bearish engulfing pattern a humanitarian crisis could result when the release of sustained terrific cold into regions who have become unaccustomed actually occurs.

Thanks for the feedback and VERY GOOD CONVERSATION.

Ed, enjoy your break! It appears that we have quite a climate adventure ahead.

Dean

Greg said...

Hello Ed,

I was wondering why a continuation of an inactive MJO, or one that exists in the Indian Ocean, may ruin the chance for an El-Nino to develop?

Isn't the idea to have less convection in the EH?

Or is it OK to have convection in the west Pacific Ocean because of the westerly winds it provides?

Ed Berry said...

Hello Greg,

Thank you for the comment. First, there are some basic research issues related to your questions that I cannot address here. For instance, the MJO only explains ~10-20% of tropical forcing, meaning that you do not need MJOs for either warm or cold events. An important point I have been trying to make is that the possibility may exist for the next several months to have atmospheric-oceanic coupling including tropical convection to continue the warming of the west Pacific Ocean. Yes, wwbs and downwelling oceanic Kelvin waves are a component to the complex dynamics involved.

Secondly, as I have also been stressing monitoring is the best we can do at this point. Many GCMs, etc.,are suggesting El-Nino only because the "initial conditions" have warmed. Some of these same models did not predicted the recent observed west Pacific warming. We cannot dismiss the real possibility a weak rendition of La-Nina returning during the upcoming boreal cold season.

Ed

Harold Ambler said...

Hi Ed,

I heard from the NWS that you had left NOAA and gone to work in Houston. I would love to interview you about the climate picture at present and about Atmospheric Insights.

Thanks in advance.

Regards,

Harold