Current SOI Trends and La Nina

['CaneFreak]

You know as well as I do, that we have not seen the typical La-Nina type conditions in the Atlantic thus far this season. Just ask Ingrid, 97L, and a BUNCH of Invests this year that have been rolled up for one reason or another. It has been a long hard road for the tropics this year and if we had true La-Nina conditions this year, I think a lot of you would agree with me that this season could have been JUST ABOUT as active as 2005 had the La-Nina conditions set in earlier in the season. Ok, now you can start bashing.

['CaneFreak]

Ok, lets think about this one for a minute...to defend my point further I would like to add the fact that Phil Klotzback and the CSU team did mention in their last update that the overall pressure in the Atlantic was about as low or lower than the long term average this year for the month of August. I think the suppressed August CV development due to the strong Azores high and the dry air, SAL, etc. put a cap on the season early on and then later in the year....the Upper Level Winds came crashing down on this area. Also, the below average SSTs out there earlier this season were also an inhibitor. So, had it not been for poor upper level conditions and the other things mentioned in this post, we could have easily ended up with just about as much activity as was the case in 2004 and 2005. NOW you can start bashing.

[hurricanetrack]

SSTs are actually warmer now across the Basin, relative to avg, than anytime this season:

http://www.osdpd.noaa.gov/PSB/EPS/SST/d ... 4.2007.gif

Not bad- especially west of 40 degrees longitude. October could indeed be one for the ages....time will tell.

[Ptarmigan]

It is true that La Nina means a more active hurricane season. However, 2005 hurricane season had a weak El Nino heading into Neutral than La Nina.
2005 4 3 3 3 5 5 4 3 0 -3 -5 -5
JMA-ENSO

2005
0.6
0.5
0.3
0.4
0.5
0.3
0.2
0.0
0.0
-0.2
-0.4
-0.7
CPC-ENSO

Also, it is rare to seen monsoonal troughs in the Atlantic and I believe 2005 had a monsoonal trough. I believe monsoons play a role in tropical cyclone development.

['CaneFreak]

Ok, now I am changing the title of this thread. It appears now from the SOI (Southern Oscillation Index) that we are now trending away from a La Nina pattern. It may have peaked a few weeks ago and now it is on the decline. I agree with the CPC in saying that we HAD La Nina a couple of weeks ago, but now I am not so sure with the recent SOI trends. This is certainly strange for a moderate La Nina. We dont go through SOI trends like this in a REAL La Nina. I am now thinking that this negative trend we are seeing may be linked with other climatic factors and causing this strong shear we have seen all year. This has really been a weird season. Shear is hardly ever an issue in seasons with La Nina.

[Jim Hughes]

Ok, now I am changing the title of this thread. It appears now from the SOI (Southern Oscillation Index) that we are now trending away from a La Nina pattern. It may have peaked a few weeks ago and now it is on the decline. I agree with the CPC in saying that we HAD La Nina a couple of weeks ago, but now I am not so sure with the recent SOI trends. This is certainly strange for a moderate La Nina. We dont go through SOI trends like this in a REAL La Nina. I am now thinking that this negative trend we are seeing may be linked with other climatic factors and causing this strong shear we have seen all year. This has really been a weird season. Shear is hardly ever an issue in seasons with La Nina.

We saw the SOI go out of phase with the last lengthy La Nina between 98-00. It's no big deal.

['CaneFreak]

Ok, now I am changing the title of this thread. It appears now from the SOI (Southern Oscillation Index) that we are now trending away from a La Nina pattern. It may have peaked a few weeks ago and now it is on the decline. I agree with the CPC in saying that we HAD La Nina a couple of weeks ago, but now I am not so sure with the recent SOI trends. This is certainly strange for a moderate La Nina. We dont go through SOI trends like this in a REAL La Nina. I am now thinking that this negative trend we are seeing may be linked with other climatic factors and causing this strong shear we have seen all year. This has really been a weird season. Shear is hardly ever an issue in seasons with La Nina.

We saw the SOI go out of phase with the last lengthy La Nina between 98-00. It's no big deal.

Thanks Jim. I guess I take the SOI too seriously sometimes.