concensus on La Nina....why so difficult?

[buckeye]

Why is it seemingly so difficult to get a concensus on the current state of the LaNina? I have read everything over the last couple of weeks from it's weakening, to it's holding steady, to it's peaked, to this (by jb in this morning's column): The SOI though is about to set December record, meaning the La nina is roaring . So now add 'roaring' on the list...lol

I realize there are different regions, but isn't it still described in general global terms?

[mitchnick]

Why is it seemingly so difficult to get a concensus on the current state of the LaNina? I have read everything over the last couple of weeks from it's weakening, to it's holding steady, to it's peaked, to this (by jb in this morning's column): The SOI though is about to set December record, meaning the La nina is roaring . So now add 'roaring' on the list...lol

I realize there are different regions, but isn't it still described in general global terms?

Buckeye, JB is also grinding the global cooling axe so I think his agenda is to push the NINA as much as possible since he thinks ENSO is closely related to global temps.

[donsutherland1]

Why is it seemingly so difficult to get a concensus on the current state of the LaNina? I have read everything over the last couple of weeks from it's weakening, to it's holding steady, to it's peaked, to this (by jb in this morning's column): The SOI though is about to set December record, meaning the La nina is roaring . So now add 'roaring' on the list...lol

I realize there are different regions, but isn't it still described in general global terms?

The CFS forecasts that the La Niña will continue to strengthen. The data might be hinting at such a development:

R3.4 Anomalies:

September 2010: -1.57

October 2010: -1.58

November 2010: -1.45

Week centered around:

December 1, 2010: -1.5

December 8, 2010: -1.5

December 15, 2010: -1.4

December 22, 2010: -1.7

Right now, the data suggest that it is stable. Additional data will be needed to determine whether it is strengthening as forecast. There certainly is no credible evidence yet that it has peaked or is weakening.

[MN Transplant]

Why is it seemingly so difficult to get a concensus on the current state of the LaNina? I have read everything over the last couple of weeks from it's weakening, to it's holding steady, to it's peaked, to this (by jb in this morning's column): The SOI though is about to set December record, meaning the La nina is roaring . So now add 'roaring' on the list...lol

I realize there are different regions, but isn't it still described in general global terms?

The data are the actual "truth" of what is happening, but people can take different interpretations from it. You can pretty much make the case for any of the above statements. A very basic take is that the Nina had a peak a couple of months ago and then weakened somewhat, but is rebounding back towards another peak which may or may not be more intense that the first. There is no doubt though, that this is a significant event.

[Carvers Gap]

Interesting assessment by the Australian Bureau of Meteorology.

http://www.bom.gov.au/climate/enso/

[Whacker77]

I've seen some data on another board which suggests the temperatures are slightly warming or at least have tried to warm. Over at stormvista.com, Harry has posted a chart showing the various temperatures of the ENSO regions since December 1. The temps appeared to warm early in the month, then back off. Now, they seem to be warming somwhat again, but it doesn't look large at this point.

As for why this la nina is difficult to find a consensus, when was the last time we had one with a negative PDO, massive high latittude blocking, and the sun so dormant? Information is probably pretty sketchy so it makes it a crap shoot as to what is likely to happen this coming month and in February. That's just must uneducated view.

[wall_cloud]

I believe Whacker77 is correct in the 2nd paragraph. The blocking ridge that tends to develop over the west coast in La Nina years can have significant impacts on model performance. For one, the models like to break down blocking patterns to quickly in general. This leads to a more progressive forecast than is typically observed in the real atmosphere. Speaking from a western/central North America viewpoint...the shortwaves that ride the westerlies are deflected across the northern latitudes and the models tend to have poor performance with this systems as they dive southeast in the northwesterly flow aloft across the central CONUS. When a wave does sneak underneath the synoptic ridge out west, it tends to be dampened as it moves over the more barotropic region. If these systems can reach the plains in tact, there may be a substantial temperature gradient that could cause the waves to rapidly deepen (another poorly handled scenario). There are also those systems that defy what we tend to expect in La Nina. These may not catch us by surprise, per se, but we tend to underplay their impacts several days in advance given the typical climatology. There are other reasons but I'd thought I'd throw those out there while I have a few minutes.