LA NINA!!
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cycloneye
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In other words after all the good replies here not so fast to proclaim la nina has arrived because many variables can happen to veer ENSO one way to another but right now as long as el nino 3-4 regions remain more warm that el nino 1-2 just west of South America it is still neutral.Now later in may let's see what the new models imput will be for ENSO to see if they haved changed from the neutral forecast.
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Windtalker wrote:Since I'm new, I have some questions....The last STRONG La Nina was in 1988 and we only had 10 named storms that year...one being "Gilbert" a monster...how can everyone say that in a La Nina year to expect more storms..I'm alittle confused but what else is new...Thanks
1) There were 12 storms (one post-season analysis tropical storm) not 10, the average is 9.6 storms. Seasons have been so active recently I think people have lost sight of what "average" is.
2) There were 3 intense hurricanes, average is slightly over 2. There were slightly less than an average number of hurricanes.
A strong La Nina guarantees you won't have a well-below-average season, but it really doesn't increase a season well above what an average La Nina would do, in and of itself.
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The newest SST analysis from TPC is available for the last week...showing a couple of -2C isotherms and cooler than last weeks analysis.
Goven what we've seen from the Otis model this is not much of a shock, but still worth noting.
http://www.nhc.noaa.gov/gifs/pac_anom.gif
Hmmmm.....
MW
Goven what we've seen from the Otis model this is not much of a shock, but still worth noting.
http://www.nhc.noaa.gov/gifs/pac_anom.gif
Hmmmm.....
MW
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Guest
Actually, a westerly QBO will allow an exageration of a cool enso event developing. This combined with as USAWx1 stated in another thread, the walker circulation.
With the upper level westerlies from the QBO, and the easterly winds at the surface off the west coast of S. Amer. and this is also combined with sinking air off the west coast of S. Amer, we can see an exuberated cooling pool of the equatorial eastern pacific. This is also indicated by an increase in thunderstorm activity over Indonesia.
This would be normal to see cooler SST's in the eastern equatorial pacific, even with a neutral enso indicated further by average anomolies across the remainer of the enso region.
So we are still seeing a La Nada, neutral enso. Any indications of a La Nina will be defined by June. We'll see what happens. Either way, we're in for a busy season.
This is why I mentioned teh westerly QBO. Even though it's an upper level occurance, it still has an affect.
Look at a seabreeze front. When the wind blows east along the Florida east coast, and meets the warmer air inland, what happens. The air rises, and is replaced eastward in the higher levels, creating a small scale circulation. The walker circulation is a much larger scale, and almost the same result. With sinking air off the west coast of S. America, we will normally see slightly cooler sea surface temps being teh sinking air is from where, from above where the air temps are cooler.
With the upper level westerlies from the QBO, and the easterly winds at the surface off the west coast of S. Amer. and this is also combined with sinking air off the west coast of S. Amer, we can see an exuberated cooling pool of the equatorial eastern pacific. This is also indicated by an increase in thunderstorm activity over Indonesia.
This would be normal to see cooler SST's in the eastern equatorial pacific, even with a neutral enso indicated further by average anomolies across the remainer of the enso region.
So we are still seeing a La Nada, neutral enso. Any indications of a La Nina will be defined by June. We'll see what happens. Either way, we're in for a busy season.
This is why I mentioned teh westerly QBO. Even though it's an upper level occurance, it still has an affect.
Look at a seabreeze front. When the wind blows east along the Florida east coast, and meets the warmer air inland, what happens. The air rises, and is replaced eastward in the higher levels, creating a small scale circulation. The walker circulation is a much larger scale, and almost the same result. With sinking air off the west coast of S. America, we will normally see slightly cooler sea surface temps being teh sinking air is from where, from above where the air temps are cooler.
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Big old long post coming...get ready...here goes...I'm not messing with spellcheck so please forgive any spelling errors in advance:
Before going further I think it is helpful for anyone reading, who may not be familiar with some the cirulation patterns governing the Pacific in paticular, to check out this link, it does a pretty good job of summing up the connections to ENSO and describes the Walker circulation in good detail about halfway down:
http://www.bom.gov.au/lam/climate/level ... elnino.htm
While it may be possible in theroy for a western QBO to somehow enhance conditions that would lead to a Nina, I have never seen any practical research drawing this conclusion. So while possible, as far as I know the connection is unproven.
It took me a while to find this today, but I remembered Gray mentioning something about the Walker circulation in one of his forecasts not too long ago and it's impact. At long last I found it in the info in the April 2003 Hurricane outlook:
The westerlies down there (near the equator), according to Gray atleast, appear to create upper divergance and hence increased convective activity during warm events over the eastern Pacific, but are not related to the strataspheric QBO.
Getting off my duff even further, Gray addresses this issue again in this years outlook, but I had fogotten that already:
All this is well and good, but still no direct evidene that these to distinct patterns are related. The QBO is way way way up at something like 10 to 30MB. The Walker impact on westerlies in the upper atmosphere is way way "down" at 200MB.
Again, I don't know this for sure because I haven't studied it in any great detail, but I don't see anything that suggests a link (see the 1997 example, westerly QBO, raging Nino, no August storms and 1 September hurricane (never happened before even in the pre-satellite era)).
Going even further out I'll go back to one of my initial points...I can find no direct link between ENSO, one way or the other, and the QBO. The QBO flips back and fourth every 2 years (the longest period ever observed being 36 months, the average 28 months), yet warm and cold nino events can go 7 - 10 years between Nino and Nina.
If anyone has something contrary to this...please post a link if you can. I love reading about this stuff.
MW
BarometerBob wrote:Actually, a westerly QBO will allow an exageration of a cool enso event developing. This combined with as USAWx1 stated in another thread, the walker circulation.
Before going further I think it is helpful for anyone reading, who may not be familiar with some the cirulation patterns governing the Pacific in paticular, to check out this link, it does a pretty good job of summing up the connections to ENSO and describes the Walker circulation in good detail about halfway down:
http://www.bom.gov.au/lam/climate/level ... elnino.htm
While it may be possible in theroy for a western QBO to somehow enhance conditions that would lead to a Nina, I have never seen any practical research drawing this conclusion. So while possible, as far as I know the connection is unproven.
It took me a while to find this today, but I remembered Gray mentioning something about the Walker circulation in one of his forecasts not too long ago and it's impact. At long last I found it in the info in the April 2003 Hurricane outlook:
Dr William Gray, April 2003 wrote:Predictor 2. February 200 MB U in the Central Tropical Atlantic (-)
(5°S-10°N, 35-55°W)
Easterly upper-level zonal wind anomalies off the northeast coast of South America imply that the upward circulation associated with the Walker Circulation of a warm ENSO event has shifted westward and that cool La Niña conditions are likely to be present for the next 4-6 months. El Niño conditions shift the upward portion of the Walker Circulation eastward and cause 200 mb westerly anomalies in this area. Such 200 mb westerly wind anomalies are associated with increased upper-level divergence in the East Pacific which occurs with warm ENSO conditions.
The westerlies down there (near the equator), according to Gray atleast, appear to create upper divergance and hence increased convective activity during warm events over the eastern Pacific, but are not related to the strataspheric QBO.
Getting off my duff even further, Gray addresses this issue again in this years outlook, but I had fogotten that already:
William Gray, April 2004 wrote:Easterly upper-level zonal wind anomalies off the northeast coast of South America imply that the upward branch of the Walker Circulation associated with ENSO remains in the western Pacific and that cool ENSO or La Niña conditions are likely to be present in the eastern equatorial Pacific for the next 4-6 months. El Niño conditions shift the upward portion of the Walker Circulation to the eastern Pacific and cause 200 mb westerly wind anomalies over the tropical Atlantic. These anomalies inhibit Atlantic hurricane activity.
All this is well and good, but still no direct evidene that these to distinct patterns are related. The QBO is way way way up at something like 10 to 30MB. The Walker impact on westerlies in the upper atmosphere is way way "down" at 200MB.
Again, I don't know this for sure because I haven't studied it in any great detail, but I don't see anything that suggests a link (see the 1997 example, westerly QBO, raging Nino, no August storms and 1 September hurricane (never happened before even in the pre-satellite era)).
Going even further out I'll go back to one of my initial points...I can find no direct link between ENSO, one way or the other, and the QBO. The QBO flips back and fourth every 2 years (the longest period ever observed being 36 months, the average 28 months), yet warm and cold nino events can go 7 - 10 years between Nino and Nina.
If anyone has something contrary to this...please post a link if you can. I love reading about this stuff.
MW
Last edited by MWatkins on Mon May 03, 2004 9:32 pm, edited 1 time in total.
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Anonymous
The QBO oscillates back and forth between the negative (east) and positive (west) phase regularly. the ENSO displays a considerably greater amount of variability, driven by the long term cycles in the PDO.
The ENSO is actually more of a higher frequency function of the lower frequency PDO. or in other words, warm and cold ENSO episodes occur more frequenty (lasting months on end) whereas the warm and cold cycles in the PDO operate on a decadal scale.
As for the connection between the ENSO and QBO, the two in combination w/ one another have a greater impact on wintertime jet stream patterns across the Northern Hemisphere.
Otherwise, they are two different climate factors and should be treated as such.
The ENSO is actually more of a higher frequency function of the lower frequency PDO. or in other words, warm and cold ENSO episodes occur more frequenty (lasting months on end) whereas the warm and cold cycles in the PDO operate on a decadal scale.
As for the connection between the ENSO and QBO, the two in combination w/ one another have a greater impact on wintertime jet stream patterns across the Northern Hemisphere.
Otherwise, they are two different climate factors and should be treated as such.
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meteorologyman
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meteorologyman wrote:This will be my last post for blast in the pass for today I have school tomorrow, you should be able to compare this w/2007 and let me tell you I'm seeing Dej vu, somtime I'm wondering if I'm reading 2007 when i'm in 2004
I wouldn't base analog years off of what is posted on message boards. Had this forum been around for a few decades you'd probably find that similar things would have been said about other seasons before they started. A lot of ppl were wrong about Nina in 04. How does that make 2007 similar to 2004 if in fact we get a La Nina this year? Even if we don't El Nino/La Nina is only 1/100th of the puzzle.
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