El Nino, La Nina, and Netural Years

[Ptarmigan]

On this discussion of El Nino and less active seasons in the Atlantic Basin...

Is it then accurate to state that more active years in the Eastern Pacific usually mean fewer storms in the Atlantic (and vice versa)?

Eastern Pacific: http://weather.unisys.com/hurricane/e_p ... index.html (1951-2008)
Atlantic Basin: http://weather.unisys.com/hurricane/atlantic/index.html (1851-2009)

I know some years it doesn't work out this way ... looks like 2005, for example, was active in both basins (15 Easter Pacific/28 Atlantic), while other seasons, such as 1977, have been relatively quiet in both basins (8 Eastern Pacific/7 Atlantic). In tropical seasons such as 1977, what would account for less activity in both basins? Water temperature? Shear? Natural climate cycle?

I know '77 did have Anita, a very powerful Cat 4 in the southern Gulf. Here in Louisiana we experienced Babe, a relatively weak tropical system that barely reached hurricane status.

1977 is an interesting one. It is not really known why it was inactive for both East Pacific and Atlantic. Even West Pacific was less active. I know the winter of 1976-77 was El Nino, but a weak one. It was the time that Miami saw snow. Also, it went El Nino in late 1977, which was weak too. Also, for the Atlantic we were in a cooler phase. The Pacific Decadal Oscillation (PDO) went into a warm phase in 1977.

[clfenwi]

It seems like research indicates that while there isn't a statistically significant relationship between the number of Atlantic and East Pacific storms, the Accumulated Cyclone Energy (ACE) of the two basins does offset one another.

Some papers for those so inclined:

A Look at Global Tropical Cyclone Activity during 1995: Contrasting High Atlantic Activity with Low Activity in Other Basins

From the conclusion:

Despite the strong reduction of the annual number of TCs in most basins during the aforementioned NAT prolific years, there is no overall correlation between the annual number of TCs in the NAT and the annual number of TCs in any other major TC basin (i.e., the WNP, ENP, and SH). In fact, the only statistically significant correlations of annual numbers of TCs are weak positive correlations between the WNP and the ENP, between the SH and the WNP, and between the SH and the ENP

(NAT=North Atlantic, WNP/ENP =Western/Eastern North Pacific SH=Southern Hemisphere)

The Interannual Variability of Tropical Cyclones

Again, from the conclusion

There is no observed tendency for above-normal cyclone activity in one basin to be compensated by net below-normal activity averaged over the remaining basins when all storms are considered. However, there is a tendency for the interannual variability of more intense storms (categories 3-5) to be greater than would be predicted from independent variations in the five basins. This is particularly true for the strongest storms (categories 4-5). Hence, the myth of the 80 cyclones is false.

The "80 cyclone myth" is the idea that the number of cyclones globally is relatively fixed, such that above average activity in one basin would be off set by an aggregate reduction in activity in the other basins.

The paper found a statistically significant negative correlation for the number of category 3-5 hurricanes in the Atlantic vs the number in the Eastern Pacific basin (and Western Pacific basin as well).

Finally, from the conclusion of Northern Tropical Cyclone Activity:

EP+NA ACE has largely compensated during the past three decades and
exhibits no significant trend [Figure S2]. The increase in NA TC frequency and intensity
mainly since 1995 has corresponded to a concomitant downturn in the EP. The overall
ratio of EP+NA ACE has remained stable throughout the period examined.

[StormClouds63]

Is the current weather pattern over the northwest and central gulf coast, with a strong high pressure in place, typical of an El Nino set-up? I'm speaking specifically of southeast Texas and Louisiana. Currently, we're under a strong high pressure with very little rain predicted for the near future. I seem to recall that in 1980 this type of weather was in place for most of the summer.

Here in southwest Louisiana, I also recall the summers of 1995, 1999, 2000, and 2005 with above average temperatures and little rainfall, indicative of a strong high pressure. In 2000, during the week of Labor Day, for several days in a row, temperatures exceeded 100 degrees. However, in checking to see whether those years were El Nino seasons, doesn't seem to a connection. Here's the link previously posted:

http://www.cpc.noaa.gov/products/analys ... ears.shtml

I bring up this question because I thought I read on the board a post regarding Texas summer weather patterns and typical El Nino seasons.

[StormClouds63]

Follow-up:

From KATC-TV (Lafayette, LA) Weather Blog:
We’re not quite as dry as we were in 2000, but if we continue with this dry weather for most of the summer, the dry ground could put our temperatures higher and higher. If you remember, late August and early September 2000 we had 7 straight days of temperatures over 100. Two of those days we hit 103, and August 30 we hit 104. The record high temperature for the month was broken for both August and September that year.

From Lake Charles (LA) National Weather Service:
LONG-RANGE WEATHER MODELS SHOW OUR REGION IS IN STORE FOR AT LEAST A COUPLE OF WEEKS OF WARMER...AND DRIER WEATHER. WITH MOST OF THE REGION ALREADY IN AN ABNORMALLY DRY CONDITION...WE WILL BE MONITORING THE POSSIBILITY OF US RETURNING TO AT LEAST A MODERATE DROUGHT BY THE END OF THE MONTH.

Here is the hurricane activity for 2000:
http://weather.unisys.com/hurricane/atl ... index.html
2000 was a LaNina.

There have also been comparisons to Summer, 1980. Here is the hurricane activity for 1980 (which does includes Allen): http://weather.unisys.com/hurricane/atl ... index.html
1980 was neutral.

The other summers with a similar set-up with high pressure and dry conditions were 1995 (LaNina), 1999 (LaNina), and 2005 (neutral). This season, however, appears to be headed for at least a weak El Nino.

What conclusions, if any, can be drawn about possible hurricane activity for this year? It would seem good news for the northwest and central Gulf if that High stays in place, and we do, indeed, move into at least a weak El Nino. I'm a real novice regarding tropical weather, so any additional information would be welcome.

[SETXWXLADY]

Hi. New here. So hope I get this right.

What conclusions, if any, can be drawn about possible hurricane activity for this year? It would seem good news for the northwest and central Gulf if that High stays in place, and we do, indeed, move into at least a weak El Nino. I'm a real novice regarding tropical weather, so any additional information would be welcome.

I found this article while looking for something completely different. Lol. While not entirely about the ENSO effects it is very interesting and does touch on the EL NINO/LA NINA. Mainly of interest to SETX/SWLA. However there may be reports like it from other areas. For all I know there are newer ones as well.

http://www.srh.noaa.gov/topics/attach/html/ssd98-16.htm

A Historical Study of Tropical Storms and
Hurricanes that have affected Southwest
Louisiana and Southeast Texas

Hope it helps.

[vbhoutex]

This is a partial quote from the whole paper referenced in the post above. I find it very interesting and somewhat disheartening after going through Ike last year.

Possible Effects of ENSO (El Niño/Southern Oscillation)

Years of moderate to strong warm ENSO events were checked for any possible relationship with tropical cyclones affecting Louisiana and southeast Texas. These warm events seemed to have no significant correlation to an increase or decrease in tropical storms and hurricanes entering the area; it has been recently discovered though that it does make a difference further down the Texas coast.

Unexpectedly, ENSO events seemed to have a strong correlation to major hurricanes in this area. Five of the eight major hurricanes struck the region during the middle of moderate to strong El Niño events. If one expands the criteria to within one year of a moderate ENSO seven of eight become included. Further study is needed to totally resolve this issue.

The "area" is basically within 150 miles of the Lake Charles NWS office.

[StormClouds63]

SETXWXLADY and vbhoutex:

Thanks for the link and your responses. I'm a bit surprised by the conclusions of the study. I'll take heat and drought over another Rita and/or Ike. Unfortunately, nature has a way of compensating for these extremes. Here in southwest Louisiana, the focus seems to be on those two recent storms and the storm surge. However, another Allison could be just as devastating with flooding. The only good thing about Ike and Rita is that these storms did not stall and cause excessive rainfall to go along with the high winds and storm surge.

[SETXWXLADY]

VB. That same phrase stuck out to me as well. Another student of meteorology on another site said that for some reason, during an El nino, the ssts in the gulf of Mexico are anomously warmer. And the position of the jet stream lessens wind shear thereby aiding in tropical cyclone formation. I don't know how accurate that is because it seems to be at odds with what I've heard everyone saying about how El nino affects the Atlantic season. However, it doesn't seem at odds with the results of that study.

Storm cloud. The study suprised me as well. I just wonder how much the last few years storms have changed their findings, if at all.

As I stated before, I'm new to this. And would apreciate any feedback anyone has to offer on this subject.

[vbhoutex]

VB. That same phrase stuck out to me as well. Another student of meteorology on another site said that for some reason, during an El nino, the ssts in the gulf of Mexico are anomously warmer. And the position of the jet stream lessens wind shear thereby aiding in tropical cyclone formation. I don't know how accurate that is because it seems to be at odds with what I've heard everyone saying about how El nino affects the Atlantic season. However, it doesn't seem at odds with the results of that study.

Storm cloud. The study suprised me as well. I just wonder how much the last few years storms have changed their findings, if at all.

As I stated before, I'm new to this. And would apreciate any feedback anyone has to offer on this subject.

Not sure what they are basing those statements on. The GOM SST's have been extra warm in other that El Nino years and as of yet aren't especially warm compared to normal(of course the el nino hasn't kicked in yet either). Of note here is that in the GOM especially heat content and depth is also very important. I'd like to see some support of this statement that they have backed up with facts before buying into it.
The jet stream may be displaced further north in El Nino years(I don't remember) which would lessen the shear as stated.

[SETXWXLADY]

VB. That same phrase stuck out to me as well. Another student of meteorology on another site said that for some reason, during an El nino, the ssts in the gulf of Mexico are anomously warmer. And the position of the jet stream lessens wind shear thereby aiding in tropical cyclone formation. I don't know how accurate that is because it seems to be at odds with what I've heard everyone saying about how El nino affects the Atlantic season. However, it doesn't seem at odds with the results of that study.

Storm cloud. The study suprised me as well. I just wonder how much the last few years storms have changed their findings, if at all.

As I stated before, I'm new to this. And would apreciate any feedback anyone has to offer on this subject.

Not sure what they are basing those statements on. The GOM SST's have been extra warm in other that El Nino years and as of yet aren't especially warm compared to normal(of course the el nino hasn't kicked in yet either). Of note here is that in the GOM especially heat content and depth is also very important. I'd like to see some support of this statement that they have backed up with facts before buying into it.
The jet stream may be displaced further north in El Nino years(I don't remember) which would lessen the shear as stated.

Thanks VB. I'd like to know what he based that on too.