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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Yeah...I don't see any either...yet....
1 hurricane
0 major hurricane
sound reasonable
Yes yes I know there is shear in the central carrib
One thing is for sure 2009 should be an interesting season.
Any chance it could make it far enough west as to affect Hawaii?
Most likely abaove average since it will plus Nino year. years directly after and before ENSO events are active.
Good evening...
Interesting... since this is a similar scenario I showed last night on the CFS output for 22+HR where a frontal area becomes the focus for development for a low to develop late next week. I guess the CFS wasn't the only model pulling my leg. Indeed if ECMWF persists and other models join in then thing will get interesting.
it would prob be developing...:)
i really doubt it, its too far south, and if it
does get picked up to the north dry air would kill it
to find 95 E, look at the very bottom tip
of the baja peninsula on mexico, and then follow the line downwards..
another thing to note is that the whole state of hawaii is under 60 knots of wind shear.. even if it does make it to hawaii it wont be anything more than a thunderstorm imo. ask the expert for back up bc i could be wrong
300hr+ hmm dont think it will happen lol.
But if the season only had 6 storms, it would not surprise me.And if the season had 13 storms, that would not surprise me either.
30-50?
Waves can and do produce convection in the face of vertical shear (diffluence) which is not related to cyclogenesis. However, I am watching this one. But currently I would not say its looking good.
looks like 5-20 to me :/
lol true
Link
El Nino conditions return to affect U.S. weather
Link
lol
Obviously, I'm not taking the model output seriously, having fun looking WAY out into the future....kind of like the 384 hr GFS model. Next time I'll put a LOL at the end of the link.
Anyone got a 1000 day forecast instead? LOL.
Just having fun with ya...
Can anyone point out one instance where any model actually got anything right more than a day out this entire year so far ?
LOL LOL....Here ya go!!, actually it is 1008 hours out...lol. Link
Any body got a year 3000 forecast.
where is that? in the pacific right?
LMBO...nope, but how about a model forecast for the evening of April 8th, 2010 (6648 hrs out) Link
Link
(This above statement is indeed a joke about getting excited about long range forecasts. If the GFS were actually run for that long the soil moisture in the Everglades and around Phoenix would probably swap in model land. Everything weather coming from a dynamical model further than 7 days should be treated as absurd, because it likely is.)
Yeah, you're probably right...I was just curious because Iniki (not to drop names or say this will turn out anything like that) followed a somewhat similar path across the Pacific and stayed relatively far to the south, and then curved north suddenly after the ridge over Hawaii weakened. Although the shear and dry air probably weren't present at that time.
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