El Niño chances rising for hurricane season

By: Dr. Jeff Masters , 3:38 PM GMT on May 29, 2009

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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

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992. SLU
1:45 PM GMT on June 01, 2009
Quoting Weather456:
A well-define tropcial wave along an anomalously south ITCZ.



This could be the disturbance responsible for the Air France plane malfunction
Member Since: July 13, 2006 Posts: 12 Comments: 4731
991. TheCaneWhisperer
1:43 PM GMT on June 01, 2009
Quoting stillwaiting:


I can say that scenerio w/not play out...remember 90L was supposed to form in the same area,according to the long range models...instead it formed near SE cuba and dissapted....never trust any model that far out,96-120hrs max,and that just gives us a ruff idea where a TC may form,IMO



Model support was Non-existent early on with 90L. At least a few of the majors are on board with this area which should lend it some credence. Not to the strength but the fact that there is a good possibility of a formidable entity in that area at that time.
990. IKE
1:40 PM GMT on June 01, 2009
NEW BLOG!
Member Since: June 9, 2005 Posts: 23 Comments: 37858
989. nrtiwlnvragn
1:39 PM GMT on June 01, 2009
New Blog
Member Since: September 23, 2005 Posts: 13 Comments: 10462
988. TaminFLA
1:35 PM GMT on June 01, 2009
Quoting Weather456:
June 17

A bit overdone, and oh how it always tend to head for Florida.



It's only because we stick out so much, they ALWAYS look like they are comming for us :) The NHC usually has it right on the money once they get a weeks worth of data....so I follow them!
987. IKE
1:33 PM GMT on June 01, 2009
stillwaiting....90L dissipated?

After reading your post again...okay, 90L that was east/SE of Florida did and then reformed in the eastern GOM.
Member Since: June 9, 2005 Posts: 23 Comments: 37858
986. IKE
1:33 PM GMT on June 01, 2009
Quoting stillwaiting:


I can say that scenerio w/not play out...remember 90L was supposed to form in the same area,according to the long range models...instead it formed near SE cuba and dissapted....never trust any model that far out,96-120hrs max,and that just gives us a ruff idea where a TC may form,IMO


I was waiting for someone to say that.

I thought about posting a statement saying the same thing***you shouldn't trust any model beyond X amount of hours***, but decided to wait.
Member Since: June 9, 2005 Posts: 23 Comments: 37858
985. stillwaiting
1:29 PM GMT on June 01, 2009
Quoting IKE:
Full blown cane at 384 hours on the 6Z GFS....



I can say that scenerio w/not play out...remember 90L was supposed to form in the same area,according to the long range models...instead it formed near SE cuba and dissapted....never trust any model that far out,96-120hrs max,and that just gives us a ruff idea where a TC may form,IMO
Member Since: October 5, 2007 Posts: 20 Comments: 4970
984. TheCaneWhisperer
1:27 PM GMT on June 01, 2009
Quoting StormFreakyisher:
Wow hurricane season really is starting but still my guesstimate is June 19th for a storm to form.Sadly EPAC is more silent than us.


Typically when the EPAC is silent the Atlantic is not.
983. Orcasystems
1:25 PM GMT on June 01, 2009
Alright.. what am I missing... all of the models I have looked at show nothing... zilch. The closest thing I can find of even a sniff of something starting is the southwestern Caribbean?
Member Since: October 1, 2007 Posts: 81 Comments: 26493
982. tkeith
1:24 PM GMT on June 01, 2009
Quoting Orcasystems:


You just trying to give Pat a heart attack right?
he's makin me a little squeemish with that too Orca...

the Miss. River is very high and will be on the 17th...I need a Rolaids and it's just the first day of the season.
Member Since: November 1, 2004 Posts: 25 Comments: 8912
981. Cavin Rawlins
1:22 PM GMT on June 01, 2009
June Outlook
Member Since: July 24, 2005 Posts: 407 Comments: 19076
979. Cavin Rawlins
1:18 PM GMT on June 01, 2009
Quoting Orcasystems:


You just trying to give Pat a heart attack right?


lol....
Member Since: July 24, 2005 Posts: 407 Comments: 19076
978. Orcasystems
1:16 PM GMT on June 01, 2009
Quoting Weather456:
June 17

A bit overdone



You just trying to give Pat a heart attack right?
Member Since: October 1, 2007 Posts: 81 Comments: 26493
977. CaneWarning
1:15 PM GMT on June 01, 2009
Quoting StormW:


MJO is short for Madden Julian Oscillation. I will be posting a link to it under my reecommended links section later today.


Hey StormW, will you be posting your season outlook today sir, buddy, pal?
Member Since: April 26, 2009 Posts: 3 Comments: 3667
976. CaneWarning
1:14 PM GMT on June 01, 2009
Quoting Weather456:
June 17

A bit overdone



Let's hope so.
Member Since: April 26, 2009 Posts: 3 Comments: 3667
974. Cavin Rawlins
1:13 PM GMT on June 01, 2009
June 17

A bit overdone, and oh how it always tend to head for Florida.

Member Since: July 24, 2005 Posts: 407 Comments: 19076
972. IKE
1:08 PM GMT on June 01, 2009
Quoting HIEXPRESS:
IKE (Caps, 'cause we can.[also 'cause we can't change it])

Now watch them both drop it and make me out to be an idiot.

Not sure why that would be so.


Not sure why I put it in all caps. That was 4+ years ago and almost 19,000 posts ago.

Truthfully, I doubt they'll both drop it.
Member Since: June 9, 2005 Posts: 23 Comments: 37858
971. Drakoen
1:08 PM GMT on June 01, 2009
GFS 06z High res view
Member Since: October 28, 2006 Posts: 57 Comments: 29714
970. HIEXPRESS
1:06 PM GMT on June 01, 2009
IKE (Caps, 'cause we can.[also 'cause we can't change it])

Now watch them both drop it and make me out to be an idiot.

Not sure why that would be so.

456
rising cake
LOL

Jiffy pop?
Member Since: October 13, 2005 Posts: 4 Comments: 2155
969. IKE
1:00 PM GMT on June 01, 2009
Quoting HIEXPRESS:
907. IKE
00Z ECMWF still shows western Caribbean development

Yes, it first showed up on the 5/31 00z run, and has maintained over the next 2, but the track has been changing, and it's pushed out in time keeping the same position at +72 hours, one day later. Still worth watching.



I went back and looked. Looks like it really became apparent on yesterdays 12Z ECMWF run...although there's not much to it then.

I'm going out-on-a-limb. I'll say it's slightly stronger on today's 12Z ECMWF run, based on what the 6Z GFS is showing.

Now watch them both drop it and make me out to be an idiot.
Member Since: June 9, 2005 Posts: 23 Comments: 37858
968. Cavin Rawlins
12:59 PM GMT on June 01, 2009
Based on what the models are showing, the 500 mb heights show a good amount of heat and moisture content in the atmopshere which should lead to favorable outflow pattern, ie, low shear across the Caribbean over the upcoming weeks.

Normally high geopotential heights in the upper atmosphere is an indicator of convection, heat and moisture. Much like a rising cake.

Member Since: July 24, 2005 Posts: 407 Comments: 19076
967. Tazmanian
12:59 PM GMT on June 01, 2009
am looking forword to the ENSO
Member Since: May 21, 2006 Posts: 5089 Comments: 114051
966. ChrisDcane
12:58 PM GMT on June 01, 2009
stupid question wat MJO
plz tell me
965. Orcasystems
12:56 PM GMT on June 01, 2009
Blog Update
Reflector site for those at work, which now also includes Weather456, daily updates


AOI #1

AOI #2
Member Since: October 1, 2007 Posts: 81 Comments: 26493
964. K8eCane
12:55 PM GMT on June 01, 2009
thanks cane
i wasnt sure
Member Since: April 26, 2006 Posts: 5 Comments: 3040
963. ChrisDcane
12:55 PM GMT on June 01, 2009
Quoting Drakoen:
It looks like the convection and the convective area should substantially increase next week a long with lowering shear values.


what do u mean
962. ChrisDcane
12:54 PM GMT on June 01, 2009

day 1
961. CaneWarning
12:54 PM GMT on June 01, 2009
Quoting K8eCane:
i guess the plane was nowhere near the bermuda triangle?


They shouldn't have been anywhere near it. Normally crashes/landings at sea do not turn out well.
Member Since: April 26, 2009 Posts: 3 Comments: 3667
960. HIEXPRESS
12:52 PM GMT on June 01, 2009
907. IKE
00Z ECMWF still shows western Caribbean development

Yes, it first showed up on the 5/31 00z run, and has maintained over the next 2, but the track has been changing, and it's pushed out in time keeping the same position at +72 hours, one day later. Still worth watching.

Member Since: October 13, 2005 Posts: 4 Comments: 2155
959. StormFreakyisher
12:51 PM GMT on June 01, 2009
Wow hurricane season really is starting but still my guesstimate is June 19th for a storm to form.Sadly EPAC is more silent than us.
Member Since: May 16, 2009 Posts: 0 Comments: 684
958. Drakoen
12:51 PM GMT on June 01, 2009
Anything forming in the Caribbean could experience significant intensification.
Member Since: October 28, 2006 Posts: 57 Comments: 29714
957. K8eCane
12:51 PM GMT on June 01, 2009
i guess the plane was nowhere near the bermuda triangle?
Member Since: April 26, 2006 Posts: 5 Comments: 3040
956. IKE
12:50 PM GMT on June 01, 2009
Quoting CaneWarning:


Things don't look good for the plane. It reported some type of electrical problem just before it disappeared.


Doesn't look good at all for the 228 on board.
Member Since: June 9, 2005 Posts: 23 Comments: 37858
955. StormFreakyisher
12:49 PM GMT on June 01, 2009
Wow nice tropical healthy wave but shouldn't be that far out at this time of the year.And does the GFS take this Low there developing into Florida?I guess it's to early too tell.
Member Since: May 16, 2009 Posts: 0 Comments: 684
954. CaneWarning
12:49 PM GMT on June 01, 2009
Quoting IKE:
Air France flight with 228 people aboard dropped off radar today on route from Rio de Janeiro to Paris, the airline said.


Things don't look good for the plane. It reported some type of electrical problem just before it disappeared.
Member Since: April 26, 2009 Posts: 3 Comments: 3667
953. Drakoen
12:48 PM GMT on June 01, 2009
It looks like the convection and the convective area should substantially increase next week a long with lowering shear values.
Member Since: October 28, 2006 Posts: 57 Comments: 29714
952. CaneWarning
12:44 PM GMT on June 01, 2009
Quoting Drakoen:
Looks like there's some long-range computer model consensus. We'll see what happens. Nothing to buy into yet.


It gives us something to watch at least.
Member Since: April 26, 2009 Posts: 3 Comments: 3667
951. Drakoen
12:41 PM GMT on June 01, 2009
Looks like there's some long-range computer model consensus. We'll see what happens. Nothing to buy into yet.
Member Since: October 28, 2006 Posts: 57 Comments: 29714
950. Cavin Rawlins
12:37 PM GMT on June 01, 2009
A well-define tropcial wave along an anomalously south ITCZ.

Member Since: July 24, 2005 Posts: 407 Comments: 19076
949. CaneWarning
12:31 PM GMT on June 01, 2009
Quoting stormdude77:


The one in the SEGOM...near FL


Too close to home.
Member Since: April 26, 2009 Posts: 3 Comments: 3667
948. Cavin Rawlins
12:29 PM GMT on June 01, 2009
Quoting CaneWarning:


Doesn't it coincide with an upward MJO?


yea
Member Since: July 24, 2005 Posts: 407 Comments: 19076
947. stormdude77
12:28 PM GMT on June 01, 2009
Quoting CaneWarning:


Which blob? It looks like there are several?


The one in the SEGOM...near FL
946. Chicklit
12:26 PM GMT on June 01, 2009
you're a funny guy, jeff.
were you the one that came up with the joke about hebert's box? i'm still trying to remember that one. it was funny.
are we seeing el nino conditions yet?
Member Since: July 11, 2006 Posts: 14 Comments: 11047
945. CaneWarning
12:25 PM GMT on June 01, 2009
Quoting Weather456:
I have the day off today and it could not have happened on a better day. I always like to relax come June 1.

press, thanks and anytime.

Even though the GFS is almost out 2 weeks out, there is reason to it.


Doesn't it coincide with an upward MJO?
Member Since: April 26, 2009 Posts: 3 Comments: 3667
944. Cavin Rawlins
12:24 PM GMT on June 01, 2009
I have the day off today and it could not have happened on a better day. I always like to relax come June 1.

press, thanks and anytime.

Even though the GFS is almost 2 weeks out, there is reason to it.

Twins

Member Since: July 24, 2005 Posts: 407 Comments: 19076
943. K8eCane
12:24 PM GMT on June 01, 2009
917 PATRAP

Thanks so much for that blast from the past. I had to listen twice.....
Member Since: April 26, 2006 Posts: 5 Comments: 3040

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About JeffMasters

Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.