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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BTW, I just finished my 8th assignment (out of 10) for a grad course I'm taking called 'grant writing and contract administration.'
So if someone wants me to write a weather grant for them, just let me know. I'm almost an expert! LOL
seems though some don't learn from the past years though.
Our pan overflowed. My ice was like a chunk.
yep seems like a trend nightly.
Too many variables. Also why no two people from the same parents look, or even behave the same.
Have you looked outside? It's a full moon. I'll predict a named tropical system next full moon. (That's not so far on a limb.) Anyone wanna bet a Portlight tee shirt?
I would if it was not cloudy out, lol.
Tropical Cyclone Warning #2
=============================
At 0:00 AM UTC, Tropical Depression FIVE (NONAME) located at 18.7N 120.7E or 420 NM east-southeast of Hong Kong, China has sustained winds of 30 knots with gusts of 40 knots. The depression is reported as moving west at 16 knots.
Significant wave height associated with 05W is 10 feet
I still am more concerned about strength and steering than numbers, though. We'll REALLY be making progress when we can start to give seasonal forecasts that suggest reasonably accurately where the season's strongest systems are likely to go.
Full Moon, and a full blown storm in Niceville this afternoon! Wind, hail, downpour.
El Nino' amd we have had a very wet winter, spring and summer... toss in some "hot" and you've got July on the Panhandle!
Any takers?
Didn't someone say those who don't learn from the past are doomed to repeat it?
Tropical Disturbance Summary
09:00 AM JST July 10 2009
================================
Subject: Tropical Depression in Bashi Channel
At 0:00 AM UTC, Tropical Depression (1000 hPa) located at 18.7N 120.2E has sustained winds of 30 knots with gust of 45 knots. The depression is reported as moving west-northwest at 10 knots
Tomorrow is the 36th anniversary of Bahamian Independence, and the fireworks should be starting in about 1/2 hour. Since it may be a little cooler outside as well, I think I'll head out and watch.
New Providence is so tiny (and flat lol) that someone sitting on their porch on the South coast can see the Fireworks display taking place on the north side of the island....
Goodnight, all.
Hi Baha. This season so far is reminiscent of '04 for the late start; however, it is much wetter. So don't know what to compare it to.
The season may be much wetter than '04 in Florida, but in Texas we are having a serious drought. We haven't had the usual S.E.Texas rainy season this year.
Strange weather pattern so far this season. Hasn't the jet stream been a little further North this year than normal, setting in upper Midwest? Then when the jet stream dips South, it comes down dramatically, all the way into the Northern Gulf.
Tropical Cyclone Bulletin #4
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At 11:00 AM PhST, Tropical Depression Gorio (05W) located at 18.7ºN 119.5ºE or 110 kms northwest of Laoag City has 10 minute sustained winds of 55 km/h (30 knots).
Signal Warnings
=================
Signal Warning #1 (30-60 kph winds)
Luzon Region
1.Ilocos Sur
2.Ilocos Norte
Additional Information
=======================
Public Storm Warning Signal elsewhere now lowered.
TD "GORIO" is expected to enhance the southwest monsoon and bring rains over the western section of Luzon and Western Visayas.
Residents in low lying areas and near mountain slopes are advised to take all the necessary precautions against possible flashfloods and landslides.
The public and the disaster coordinating councils concerned are advised to take appropriate actions and watch for the next bulletin to be issued at 5 PM today.
I hate to say this, but Nature has a way of evening itself out. It always reminds me of the old fable about being careful what you wish for...you pray for rain and get a deluge.
I really have no idea what will happen this season. But with the intense warming and deep SSTs, one cannot help but think we're in for some virulent storms this season. And all the talk about El Nino. They've just finally decided we're having one. That is not a strong El Nino, at least not yet. So just get prepared. Make sure you get friendly with your neighbors and make them aware. That's all we can do now except watch and wait.
I was in class @ Florida Atlantic University in Boca Raton when the storm rolled in; power was knocked out and wind gust had to be in the 60-70 mph range.
There were numerous small trees, large branches, and heavy palm frawns littering the roads and parking lots thereafter. I saw a few trees split in half as if they had been struck by lightning.
By far the strongest thunderstorm my area has seen this summer!
The year of the great Mid-West Flood, I think in July 1993, the Spring & Summer in Kansas was exceptionally dry. Hardly any rain, crops were drying out... then about July 7th, here comes the rain.
Hopefully your words don't come true about Texas this year. We could use some slow, gradual rain, not bucketloads all at once.
Link
Will be interesting to say what they say about it in the a.m.
LOL
LOL... I still have the link from last year... hahahahha Link
doing well
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