Warm SSTs in Atlantic

[hurricanetrack]

In case anyone is wondering, check out the latest Reynolds map from NHC:

http://www.nhc.noaa.gov/tafb/atl_anom.gif

Wow! The Atlantic as a whole is really above normal for this current time period. No wonder we had a tropical cyclone form. This will be very interesting to watch as we get in to 2008. Remember how warm those SSTs were in 2005? This map is really showing some prominent anomalies in the Atlantic- how long they last is anyone's guess.

[Coredesat]

I pointed out in a previous thread that the warm anomalies in the subtropical north Atlantic seem to be a feature of La Nina years.

[hurricanetrack]

And those anonamlies right now are very high over a very large area of the north Atlantic. Anyone venture a guess as to why?

[Cyclenall]

And those anonamlies right now are very high over a very large area of the north Atlantic. Anyone venture a guess as to why?

Were in a La Nina. Coredesat posted that.

[hurricanetrack]

That does not answer the question. We were in a La Nina and had only 2 significant hurricanes- what happened to the others that were forecast to form? La Nina is not a blanket weather phenom that explains away certain things happening without going in to more detail.

That being said, what is it exactly about this La Nina that has made Atlantic SSTs higher than normal? And why now in December? They were just slightly above and in many cases, slightly below for the meat of the hurricane season- so why so warm now? La Nina might be the answer but what about La Nina?

[Coredesat]

La Nina doesn't necessarily increase the number of hurricanes, and increasing the number of hurricanes is not La Nina's only effect on climate. A La Nina does not automatically mean a more active season, and La Nina takes time for its associated synoptic patterns to become established (same as El Nino).

Most La Nina years I've seen maps for are associated with warm anomalies over much of the north Atlantic between late November and mid-January. The stronger the event, the warmer the SST anomalies. This looks to be a moderate La Nina - therefore, fairly warm SST anomalies.

[hurricanetrack]

"This looks to be a moderate La Nina - therefore, fairly warm SST anomalies."

But why? I am looking for why this is the case. What about a La Nina makes SSTs warmer in the Atlantic? And looking at that latest Reynolds map, the Atlantic really is above normal in a lot of places- much above in many areas too. Just trying to understand how all of this works- at least to the best of our collective abilities.

[Category 5]

Theres still much about El Nino and La Nina that we don't understand.

[Cyclenall]

It's like why the Pacific waters heat up during an El Nino or what causes it. The science behind that has been mentioned but I don't now where to get the details and specifics. It has something to do with Kelvin waves and SOI changes. I don't know much about it though.

[Tampa Bay Hurricane]

perhaps la nina + a warm cycle the earth is going into so perhaps a warmer
cycle but it's tricky.

[hurricanetrack]

Well, the El Nino I can understand. When the trades that normally blow east to west across the Equator or near by slow down, the water warms since there is not as much upwelling influence. And, during La Nina, when trades are stronger than normal, the upwelling effect is stronger and thus colder waters come up from below and cool the Pacific water column. That is a general reason why El Nino is warm and La Nina is cool in the Pacific.

But for the Atlantic to be as warm as it is now over such a large area- I really am hoping to get a grasp on why. All I will say is IF these temps are still like this come June, well, you know the potential. June is a long way off and a lot can change.

[jinftl]

Could the warm SST anomalies be partly attributable to the lack of strong cold fronts ushering in arctic air sweeping off the coast?