Modiki El Niños and Atlantic hurricane activity
It's an El Niño year, which typically means that Atlantic hurricane activity will be reduced. But not all El Niño events are created equal when it comes to their impact on Atlantic hurricane activity. Over the past 150 years, hurricane damage has averaged $800 million/year in El Niño years and double that during La Niña years. The abnormal warming of the equatorial Eastern Pacific ocean waters in most El Niño events creates an atmospheric circulation pattern that brings strong upper-level winds over the Atlantic, creating high wind shear conditions unfavorable for hurricanes. Yet some El Niño years, like 2004, don't fit this pattern. Residents of Florida and the Gulf Coast will not soon forget the four major hurricanes that pounded them in 2004--Ivan, Frances, Jeanne, and Charley. Overall, the 15 named storms, 9 hurricanes, and 6 intense hurricanes of the hyperactive hurricane season of 2004 killed over 3000 people--mostly in Haiti, thanks to Hurricane Jeanne--and did $40 billion in damage.
A new paper published in Science last Friday attempts to explain why some El Niño years see high Atlantic hurricane activity. "Impact of Shifting Patterns of Pacific Ocean Warming on North Atlantic Tropical Cyclones", by Georgia Tech researchers Hye-Mi Kim, Peter Webster, and Judith Curry, theorizes that Atlantic hurricane activity is sensitive to exactly where in the Pacific Ocean El Niño warming occurs. If the warming occurs primarily in the Eastern Pacific, near the coast of South America, the resulting atmospheric circulation pattern creates very high wind shear over the tropical Atlantic, resulting in fewer hurricanes. This pattern, called the Eastern Pacific Warming (EPW) pattern, occurred most recently during the El Niño years of 1997, 1987, and 1982 (Figure 1). In contrast, more warming occurred in the Central Pacific during the El Niño years of 2004, 2002, 1994, and 1991. The scientists showed that these Central Pacific Warming (CPW) years had lower wind shear over the Atlantic, and thus featured higher hurricane activity than is typical for an El Niño year. One of the paper's authors, Professor Peter J. Webster, said the variant Central Pacific Warming (CPW) El Niño pattern was discovered in the 1980s by Japanese and Korean researchers, who dubbed it modiki El Niño. Modiki is the Japanese word for "similar, but different".
Figure 1. Difference of Sea Surface Temperature (SST) from average during the peak of hurricane season, August-September-October, for seven years that had El Niño events (except for 2009, when the SST anomaly for July 1 - 3 is plotted). On the left side are years when the El Niño warming primarily occurred in the Eastern Pacific (EPW years). On the right are years when the warming primarily occurred in the Central Pacific (CPW years). Shown on the top of each plot is the number of named storms (NS), hurricanes (H), and intense hurricanes (IH) that occurred in the Atlantic each year. Atlantic hurricane activity tends to be more prevalent in CPW years than EPW years. An average hurricane season has 10 named storms, 6 hurricanes, and 2 intense hurricanes. Image credit: NOAA/ESRL.
What, then, can we expect the current developing El Niño event to do to 2009 hurricane activity? Kim et al. note that in recent decades, the incidence of modiki CPW El Niño years has been increasing, relative to EPW years. However, the preliminary pattern of SST anomalies in the Pacific observed so far in July (lower left image in Figure 1) shows an EPW pattern--more warming in the Eastern Pacific than the Central Pacific. If Kim et al.'s theory holds true, this EPW pattern should lead to an Atlantic hurricane season with activity lower than the average 10 named storms, 6 hurricanes, and 2 intense hurricanes. There is still a possibility that the observed warming pattern could shift to the Central Pacific during the peak portion of hurricane season, however. We are still in the early stages of this El Niño, and it is unclear how it will evolve.
Jeff Masters
Reader Comments
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Dennis!
thanks... looks like nhc has been having trouble updating pics
yea dennis was a monster
The NHC once noted that it has been a recurring theme with major hurricanes in the Gulf of Mexico. Specifically, they always tend to weaken a category or two prior to landfall. It's weird.
No the Invest was dropped at that point, so the floater is no longer updated
xD, so true.
He's not the only one.
For now but we have to wait 5 days and it can change.
The Gulf also has fairly shallow slope along most of the coastline, so there is generally less TCHP to pull from.
Also, I have finally updated my blog, feel free to check it out if you would like. (its educational, gives some things to look for along the Texas Coast, and is 100% fat-free!)
Thats why I call it Accuhype. Sometimes, I almost think that they try to "make" weather happen.
Really clear weather here today, due to high pressure, with some high clouds at times
If not a true Regional service as in run by one body, then at least a closer collaboration between neighbouring countries' Met Offices. I know something of this nature already exists, but it doesn't seem as coordinated as it could be.
Hmmm... I hadn't realized how low the numbers were. I was just thinking after u posted about Gorio that the WPac storms have been pretty mild so far.....
I'm chuckling at all the hype over the so-called late start to the season. The old Caribbean saying for July is "stand by", remember? Like a yellow caution light..... I'm also amused because the last couple of years all the historical statistics and record-recalling have been about "firsts" and "mosts". It's kinda refreshing to remember 1914, the year that does it all at the other end of the scale....
did you evere get that yahoo IM fixs yet tell me yes you did
meet me in Weather Chat:
LOL!
That's because most of the time they entrain Continental Dry Air when approaching the Gulf Coast.
I found a way to fix it, but it probably won't be until the weekend.
That is not a storm.
ment me in weather chat am wating for you we have lots too talk about
Bastardi give a lot of suggestion, remember when he forecast the develop of Debby a week before, he forecasted in 7 days to pass well north of the Leeward Islands and 7 days later to landfall in New York as a cat 2-3.
It certainly looks vigorous with abundance lower level convergence and upper level outflow. If it were to keep up like this, I might have to agree with your conclusion. However wind shear levels are high just west of it as a result of a result of a split ULL embedded in the TUTT, and it will thus be sheared up as it approaches tat region. This wave will have a better chance once it is near the SW Caribbean, as shear decreases due to the regression of the TUTT. According to the 18z NAM, the subequatorial ridge will also try to establish over the area, which is area the NAM is expecting potential cyclogenesis there. I doubt this will coalesce into a tropical cyclone, not only because shear is high, but also because of the steering patterns. The A/B high will remain potent according to the models, and will be ridging in much in the Western Caribbean. Therefore once this system reaches near the SW Caribbean, it will likely move into land, cutting off development.
SST'S of the florida coastline.
Carribean TCHP...
>
GOM TCHP...
Compared to a few weeks back its pretty signifcant.Now we have to work on el nino.
Better view...
I just returned from a two day vacation in Palm beach. The Storm was incredible; there were numerous power outages due to lightning and high winds.
Doesnt look too bad...I was expecting the Caribbean and GOM to be higher in TCHP.
From the looks of that map things might get ugly if a System can find ripe Upper Level Conditions.
Ya I heard some places got 65mph winds there.
To make any statement about the weather with 100% certainty, especially a prediction like that, seems a wee bit unrealistic, unless you've said something like "I'm 100% certain that it's currently raining at my house".
Everyday I send out a forecast I say it is 100%. I have to. Telling someone there is a 60% chance does not allow a person to make a decision. For example, you are going to fly and you say there is a 60% chance for a TS today at 2PM, they are going to look at you and say well am I wasting my time waiting around and planning or am I going to be able to fly.
Weather is not an exact science, dont make it out to be
So I guess lying to the public is not so bad after all...
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