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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you must be north of me.....we haven't got all that much. but north of me has been getting hammered all week.
Have a look at this Link.... does the "blob" have sum spin to it?
What year? I though they hit Florida
Strongs winds in the Blob off Honduras
One can also tie record breaking cold spells in Florida with the year after theory.
As follows are all significant crop damaging freeze events between 1950-2003. These dates represent the coldest day of the freeze event, with many of the events experiencing 2-4 days below freezing. Events with and * represent exceptionally damaging freezes to the citrus industry.
01/12/1982 *
01/24/1987
01/19/1997 *
01/24/2003
NEXT?
01/22/2009*
They hit Florida in 2004
2010 looks like it could be a busy season based on the fluctuations of El Nino/La Nina
Look at the last 3 cycles with this naming list.
1992: Slow season but had Andrew
1998: Acrive season, late start, had Georges and Mitch; deadliest season in recent memory
2004: Active season, late start, Charley, Frances, Ivan and Jeanne all hit Florida
That's why I leave.
ahh Thank you
NOGAPS has a system developing there in 30hrs
FLORIDA THROUGH EARLY EVENING AND POSSIBLY ON THURSDAY...
Little rain chances with SW flow in place again, eeekk.
What is a TCHP? And what does that mean? Sorry, I don't know what all these abbreviations mean...
Maximum Potential Hurricane Intensity
The maps display potential minimum pressure and maximum winds, calculated according to a method developed by Dr. Kerry Emanuel. Dissipative heating is handled according to a method described in Bister and Emanuel (1998). The maps are based on data from the 00Z global operational analysis from NCEP for the date shown on the plot. The top panel shows the potential minimum central pressure for a hurricane at any given location (in millibars). Only values less than 1000mb are shaded. Cyan squares indicate grid points where the algorithm failed to converge. Also shown are the sea surface temperatures (°C). The bottom panel shows the potential maximum wind speed expressed in terms of the type and severity of storm they would represent (TD = Tropical Depression, TS = Tropical Storm, H1-H5 = Hurricanes of category 1-5 on the Saffir-Simpson scale).
Yep, but we could expect a hurricane season similar to the incredible 1995 hurricane season with a name storm from earlier August to late September without any gap.
-- EMC Cyclogenesis Tracking Page --
Model Cycle: 2009070812
North America: Model Tracks for Mid-Latitude Cyclones
It basically is the fuel for storms.. in everyday terms
the reder it is its like 93 octane fuel...lol!
ESL GOES-12 GOM IR Loop
Also good convection in the blob in NW carrib
That looks more like a baroclinic low with an attached frontal system. It doesn't have the signature of a tropical system.
Cloud tops are rather warm. If were gonna see any near term development I'd be watching the frontal boundary across the West Atlantic.
Switching more North?
6 for the season.
The vertical shear, not switching more north but some of the lowest values since the season began.
It is lowest of any forecast, but I think it will be more than that even if the U.K forecast seems right.
Below normal season
oh ok...yeah the waters are toasty.
actually 11 is average now, the technical average is 10.6, so it is not below normal
meaning??
I think their last year predictions were 15 named storm.
actually their last year prediction was 7 or 8, it was below normal
again they are always conservative
There was Hurricane Gaston that made landfall in the Carolinas and went up into Virginia, but no direct hits.
Where are the numbers on landfalls? Predict that.
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