El Niño chances rising for hurricane season
Sea surface temperatures in the Equatorial Eastern Pacific have been rising steadily for several months, and there is now a very real possibility that an El Niño event could occur during the peak of the Atlantic hurricane season, August - October. This is important, since the number and intensity of Atlantic tropical storms and hurricanes is usually reduced during an El Niño year, thanks to the increased wind shear such events bring to the tropical Atlantic. Last month, Columbia University's International Research Institute (IRI) was giving a 30% chance of an El Niño event for the coming hurricane season; this month, they have bumped their odds up to 45%. The Australian Bureau of Meteorology notes that "recent trends are consistent with the very early stages of a developing El Niño". NOAA's Climate Prediction Center forecasts the current neutral conditions in the Equatorial Eastern Pacific will continue into the summer, but shows that their CFS El Niño model is predicting a moderate El Niño event for the coming hurricane season.
Figure 1. Sea Surface Temperature (SST) departure from average for the equatorial Eastern Pacific (the area 5°N - 5°S, 120°W - 170°W, also called the "Niña 3.4 region"). The +0.5°C mark is the threshold for El Niño conditions, and we are very close to that mark now. Image credit: NOAA's Climate Prediction Center.
El Niño forecast models
The latest suite of runs by the various computer models used to forecast El Niño offer two main forecasts for the coming hurricane season: neutral conditions will persist, or an El Niño will develop (Figure 2). There are two types of models used to make these forecasts: statistical models and dynamical models. The statistical models have been around the longest, and they rely on statistics of how past El Niño episodes have developed in order to make a forecast. Dynamical models don't care about what has happened in the past. They make a forecast by taking the current state of the atmosphere, putting the data on a grid covering the entire globe, then solving the equations that govern the physics of the atmosphere and ocean on each point of this grid every few minutes, marching forward in time for many months. These dynamical models, in many cases, are simply modified versions of the same models we use to forecast the short-term weather. For example, the NOAA's Coupled Forecast System (CFS) model is based on the GFS model that we use to track hurricanes and make short-term weather forecasts. The main difference is that the CFS model runs for many months instead of just a few days.
Figure 2. El Niño model forecasts made in mid-May. Note that for the peak part of hurricane season, August-September-October (ASO), most of the dynamical models are forecasting an El Niño event (SST anomaly greater than 0.5°C in the Eastern Equatorial Pacific). Image credit: Columbia University's IRI.
Which model to believe?
As is the case with all seasonal forecasts, El Niño forecasts are not very good, and don't do much better than flipping a coin. However, thanks to intensive research efforts and the doubling of computer power that has been occurring every 1.5 years, the El Niño forecasts by the dynamical models have improved considerably over the past few years. These models now do about as well as the traditional statistical models, and should continue to improve as computer power continues to increase and our understanding of El Niño increases. Over the past two months, the dynamical models have increasingly been forecasting the development of an El Niño this Fall. To illustrate, in March only three of the thirteen dynamical models were predicting an El Niño event for hurricane season. By mid-May, this had increased to nine out of thirteen models. However, none of the eight statistical El Niño models are forecasting an El Niño event for the Fall, and their forecasts should be respected, as well. The IRI web site has a nice tool one can use to study the performance of the individual models. To my eye, the Japanese Meteorological Agency (JMA) dynamical model has made the best El Niño forecasts over the past two years (though I haven't done a rigorous error analysis to verify this). The JMA model is predicting a weak El Niño event for the coming hurricane season, and I am going to go along with that forecast.
What will an El Niño event do to hurricane numbers?
Since the active hurricane period we are in began in 1995, there have been four El Niño events (Figure 3). During these years, the number of named storms, hurricanes, and intense hurricanes 11 named storms, 5 hurricanes, and 3 intense hurricanes. This is close to the average levels we've seen over the past 60 years--10-11 named storms, 6 hurricanes, and 2 intense hurricanes. If, on the other hand, we look at the five years that had neutral conditions, the numbers are considerably higher--18 named storms, 10 hurricanes, and 5 intense hurricanes. So, let's hope for an El Niño this year. Note, though, that one of our worst hurricane years--2004, which featured hurricanes Ivan, Charlie, Frances and Jeanne, which all affected Florida with hurricane conditions--was an El Niño year. It seems that in years like 2004, there is a lag between the time a El Niño event develops and the response of the atmosphere over the Atlantic. There is no way of forecasting at this point whether this could be the case this year. One argument against a repeat of 2004 is the presence of much lower heat content and SSTs in the tropical Atlantic this year compared to 2004.
Figure 3. Looking at the numbers of Atlantic names storms, hurricanes, and intense hurricanes since 1995.
Tropical Depression One
The season's first tropical depression formed yesterday off the coast of North Carolina, but has missed its opportunity to become the Tropical Storm Ana. Tropical Depression One is headed east-northeastward out to sea, and is now entering a region with cooler water temperatures and increased wind shear of 15 - 20 knots. The heavy thunderstorm activity associated with TD One has shrunk this morning, and high wind shear has pushed these thunderstorms to the east side of the center, exposing the surface circulation to view. Tropical Depression One will not hold together much longer, and should be history by Saturday night.
Is the formation of TD One a harbinger of an active hurricane season?
Probably not. Early season storms occurring near the U.S. coast have not been shown to be correlated with an active main portion of hurricane season during August - October. However, the situation is different if we start getting June and July storms in the deep tropics between Africa and the Lesser Antilles Islands. This was the case last year, when the formation of Hurricane Bertha in the deep tropics in July presaged an active 2008 hurricane season. According to the Hurricane FAQ, "as shown in (Goldenberg 2000), if one looks only at the June-July Atlantic tropical storms and hurricanes occurring south of 22°N and east of 77°W (the eastern portion of the Main Development Region [MDR] for Atlantic hurricanes), there is a strong association with activity for the remainder of the year. According to the data from 1944-1999, total overall Atlantic activity for years that had a tropical storm or hurricane form in this region during June and July have been at least average and often times above average. So it could be said that a June/July storm in this region is pretty much a "sufficient" condition for a year to produce at least average activity."
I'll have a detailed outlook of the coming hurricane season on Monday, the first day of the Atlantic hurricane season.
Jeff Masters
Reader Comments
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By Leigh Jones
The Daily News
Published May 29, 2009
GALVESTON — National news crews are headed back to the island this week to mark the beginning of hurricane season on Monday.
“Good Morning America’s” Robin Roberts will do live reports from Galveston during the show’s Monday broadcast.
Jim Cantore, from the Weather Channel, also will be in town on Monday, broadcasting live in front of Murdoch’s Pier on the seawall.
City officials, including Mayor Lyda Ann Thomas, have given interviews to CNN and Fox News Channel.
The national attention is good for the island, city spokeswoman Alicia Cahill said.
“So many of us feel as though our story got lost in the shuffle of the story of the banks and the presidential election,” she said. “Unlike New Orleans, we don’t see the outpouring of news media wanting to keep up with our progress and telling the story of the island. Having those folks check in with us now reminds people in the rest of the country that Galveston was the last place to have a major storm.”
By MARIA RECIO
McClatchy Newspapers
WASHINGTON -- President Barack Obama will highlight his concern about hurricane preparedness - and draw sharp contrasts with his predecessor - when he visits the Federal Emergency Management Agency's headquarters for the first time Friday.
Hurricane season begins June 1 and runs through Nov. 30.
Obama, who was critical of President George W. Bush's response to Hurricane Katrina, will be briefed by newly installed FEMA chief Craig Fugate, a Florida emergency response veteran.
"It's important for the president to go and recognize FEMA," said Rep. Gene Taylor, D-Miss., who lost his home to Katrina and was a relentless critic of FEMA head Michael Brown's botched response to the 2005 hurricane. "We all learned the hard way why it was such an important post.
Someone should do a OIL Blog entry if so inclined to discuss the topic.
Here,Here,
Talking about oil and the incredible profits the oil business generates, depresses me to no end.Need someone to get the countdown for the start of the season
Yep. I am in the camp that there is a lag in the teleconnections.
Blogger Skyepony and others usually have a LOT of info on it.
I don't know why that graph always lags a little, the same date that graph is updated, the weekly numbers in the update are too. As of monday we hit the .5 threshold. Page 5
Hades~ it was such a quick glance I failed to relize the EPAC blob is less than 10N. Showing tenacity early on there. The last 24 hr loop of it sucking in the gulf blob energy is impressive. Land & time of day may have helped. GFS totally missed that.
Why Are Gas Prices Going Up?
That fact has been most evident since 2004. Continually flipping back and forth El Nino / La Nina and not effecting weather like they should. I think it's because by the time conditions set in it was flipping back the other way. Thus, leaving Mother Nature in a virtual limbo over the past few years and it looks to continue.
LMAO, I forgot about "The Nino".
I wouldnt count on either one of those. 2004 was a neutral summer with building el nino and look what we got, besides, it only takes one to throw everything out such as Katrina.
I wouldn't either really. Hopefully the old El Nino will help us out some though.
Great Update... It was such a fun 6 months of "no storms" around here.. now I guess we get
back to the business of storm tracking.
I sure hope none of us get hit this year and we all get a break.
sometimes I post here and sometime I just lurk
but I do enjoy getting some good info from all of you.
You all have a great weekend.
;)
LOL
Probably, just snakebit luck, but I still don't have a particularly good feeling about the season. Not at all - as it only takes one!
Thanks for the update, Doc. Hoping for the best! :)
ROTFL! Too much!
LOL
Shear is still pretty high in the Gulf.
Link
Really good i need that John! very nice young man!
That said, I tend to agree with atmo; the lag theory seems to make sense.
Now, I am out on the high note seeing as how my Niño image cleared everything up.
Off to work, see everyone later.
Volusia County, Florida Flooding
I don't think the Lag is really a theroy! I think it is a fact that it takes as much a 2 months to feel the complete affects on the Atlantic.
All you got to do is look at 2004.
Heck, we've had afternoon thunderstorms in Northeast FL that have had more power and fury than this thing.
Or more. And of mind that ENSO is not the be all-end all of deterministic factors. I am of the opinion that it, when sharply one way or the other and for an extended period of time, does have a track tendency effect, which is fairly obvious. But number of storms in one basin appears to be tied much more to it's overall relative water temps in other basins (not just the ENSO swath, but as a whole). Speaks to the function of TCs.
It reminds me of 2004.
Mother nature says east we go.
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