Record Atlantic SSTs continue in the hurricane Main Development Region

By: Dr. Jeff Masters , 8:03 PM GMT on May 15, 2010

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Sea Surface Temperatures (SSTs) in the Atlantic's Main Development Region for hurricanes had their warmest April on record, according to an analysis of historical SST data from the UK Hadley Center. SST data goes back to 1850, though there is much missing data before 1910 and during WWI and WWII. The area between 10°N and 20°N, between the coast of Africa and Central America (20°W - 80°W), is called the Main Development Region (MDR) because virtually all African waves originate in this region. These African waves account for 85% of all Atlantic major hurricanes and 60% of all named storms. When SSTs in the MDR are much above average during hurricane season, a very active season typically results (if there is no El Niño event present.) SSTs in the Main Development Region (10°N to 20°N and 20°W to 85°W) were an eye-opening 1.46°C above average during April. This is the third straight record warm month, and the warmest anomaly measured for any month--by a remarkable 0.2°C. The previous record warmest anomalies for the Atlantic MDR were set in June 2005 and March 2010, at 1.26°C.


Figure 1. The departure of sea surface temperature (SST) from average for May 13, 2010. Image credit: NOAA/NESDIS.

What is responsible for the high SSTs?
As I explained in detail in a post on record February SSTs in the Atlantic, the Arctic Oscillation (AO) and its close cousin, the North Atlantic Oscillation (NAO), are largely to blame for the record SSTs. The AO and NAO are climate patterns in the North Atlantic Ocean related to fluctuations in the difference of sea-level pressure between the Icelandic Low and the Azores-Bermuda High. If the difference in sea-level pressure between Iceland and the Azores is small (negative NAO), this creates a weak Azores-Bermuda High, which reduces the trade winds circulating around the High. During December - February, we had the most negative AO/NAO since records began in 1950, and this caused trade winds between Africa and the Lesser Antilles Islands in the hurricane Main Development Region to slow to 1 - 2 m/s (2.2 - 4.5 mph) below average. Slower trade winds mean less mixing of the surface waters with cooler waters down deep, plus less evaporational cooling of the surface water. As a result, the ocean heated up significantly, relative to normal, over the winter. Negative AO/NAO conditions have been dominant much of this spring as well, resulting in further anomalous heating of the MDR waters. This heating is superimposed on the very warm global SSTs we've been seeing over the past few decades due to global warming. Global and Northern Hemisphere SSTs were the 2nd warmest on record this past December, January, and February, the warmest on record in March, and will likely be classified as the warmest or second warmest on record for April, since NASA just classified April as the warmest April on record for the globe. We are also in the warm phase of a decades-long natural oscillation in Atlantic ocean temperatures called the Atlantic Multi-decadal Oscillation (AMO). This warm phase began in 1995, and has been partially responsible for the high levels of hurricane activity we've seen since 1995.

What does this imply for the coming hurricane season?
The high April SST anomaly does not bode well for the coming hurricane season. The three past seasons with record warm April SST anomalies all had abnormally high numbers of intense hurricanes. Past hurricane seasons that had high March SST anomalies include 1969 (0.90°C anomaly), 2005 (1.19°C anomaly), and 1958 (0.97°C anomaly). These three years had 5, 7, and 5 intense hurricanes, respectively. Just two intense hurricanes occur in an average year. The total averaged activity for the three seasons was 15 named storms, 11 hurricanes, and 6 intense hurricanes (an average hurricane season has 10, 6, and 2.) Both 1958 and 2005 saw neutral El Niño conditions, while 1969 had a weak El Niño.

The SSTs are already as warm as we normally see in July between Africa and the Caribbean, and we have a very July-like tropical wave approaching the Lesser Antilles Islands this weekend. However, wind shear is still seasonably high, and the tropical waves coming off of Africa are still too far south to have much of a chance of developing. The GFS model is indicating that shear will start to drop over the Caribbean the last week of May, so we may have to be on the watch for tropical storms forming in the Caribbean then.

For those of you interested in a more detailed look at the early season tropical weather outlook, consult the excellent wunderblogs of StormW and Weather456. I'll be back with a new post on Monday.

Jeff Masters

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aquak9
"Trop storm- knocks over a beer bottle
cat 1- knocks over a six pack
cat 2- knocks over a case
cat 3- blows away a keg
cat 4- knocks over a semi-truck full of beer
cat 5- blows away semi-truck full of beer
Not taking storm surge into account, obviously
..."

hydrus "How did you find this out? Hurricane party?..:) "

Compare the Saffir-Simpson Cat. speeds with the damage parameters on the enhancedFujitaScale

And in case CycloneOz missed the rollover risk...
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The GFS is now developing a SUB-Tropical storm off of Floridas East Coast, interesting.. but will it happen? Probably not, we'll see.. We've seen Andrea in 2007. The GFS also cotinues to show energy in the Carribean in a week or two, although it's not bullish like it was yesterday. It's gonna be an interesting 2 weeks indeed, the EURO even has a very weak low, now that's something I'd look at.
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Quoting Weather456:
Good Morning

Blog Update

Tropical Update;The Caribbean’s Strive for Renewable Energy


ONe heck of a Blog update. One of the best i have seen! GREAT JOB!
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well what could be more obvious now... bp just wanted the oil, they never wanted to really stop the leak.
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1165. hydrus
Quoting aquak9:
Trop storm- knocks over a beer bottle

cat 1- knocks over a six pack

cat 2- knocks over a case

cat 3- blows away a keg

cat 4- knocks over a semi-truck full of beer

cat 5- blows away semi-truck full of beer

Not taking storm surge into account, obviously...
How did you find this out? Hurricane party?..:)
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Good Morning Everyone. Well finally getting some much needed rain here in Grand Cayman, hopefully the sister Islands is getting some too, this is driest May and year for that matter that I can remember!
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Good Morning

Blog Update

Tropical Update;The Caribbean’s Strive for Renewable Energy
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Quoting Jeff9641:


Bro i need one too......NO creamer in mine....LOL
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ok Everyone I'm out for a while I have to go get my tags for this year.... and then get oil changed before our trip to tornado ally....

I'll Check in a few hours from now....

Have a Great day

Taco :o)
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Quoting Jeff9641:


Maybe you should look a little more before calling me out. THat ridge over the NE US does steer a a developing low toward Florida next week from Bermuda.


Jeff i don't think anyone called you out. Sorry!
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Good one Keeper
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1157. aquak9
Trop storm- knocks over a beer bottle

cat 1- knocks over a six pack

cat 2- knocks over a case

cat 3- blows away a keg

cat 4- knocks over a semi-truck full of beer

cat 5- blows away semi-truck full of beer

Not taking storm surge into account, obviously...
Member Since: Posts: Comments:
1156. KEEPEROFTHEGATE (Mod)
Quoting splash3392:
they say duct tape can fix anything. It has strength, flexibility, elasticity. Just ask Myth Busters.
duct tape is like the force it has a light side and a dark side and it can hold the universe together
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1155. IKE
Quoting Jeff9641:


Maybe you should look a little more before calling me out. THat ridge over the NE US does steer a a developing low toward Florida next week from Bermuda.


Calling you out? I'm just agreeing with splash3392.

I see a small low at 192 hours on the 00Z ECMWF east of the east coast, but at 240 hours it looks like it's weakening....Link
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they say duct tape can fix anything. It has strength, flexibility, elasticity. Just ask Myth Busters.
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1153. KEEPEROFTHEGATE (Mod)
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Hey OZ I will have my laptop with me aswell as 2 video cameras and 2 other cameras so I can get as many pictures as I can....
My Laptop does have web cam with voice as well and will be a great test to see how it works...
I use a air card for my laptop so I should stay connected....

Taco :o)
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Oz if you don't have at least 1million pattens out on the suit. That would be a serious mistake if your wanting me to be your Manager.....ROFLMAO
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CycloneOz "...semi's are too slow. How about something with a little more agility and less torque? :D "

RTLSNK "How about this one? Not only does it look agile, it looks like it can also fly! :) "

In a major hurricane, the problem is getting a vehicle to stay parked where it was parked.
What's good in a Cat.3

Ain't so hot in a Cat.4

Perhaps something a bit heavier

But a Cat.5 will knock over a locomotive, so I wouldn't tether myself to something that light.

In case you are wondering... Yeah, I am trying to get you to reconsider your quest.
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Quoting CycloneOz:


Yeah brother! We got you all hyped up yesterday, didn't we! You were ready to take off and go yourself! :)


You Know It!!!!
I wanted to go yesterday for sure.... But I know I have to work this week. But when Saturday gets here I'm "Gone".....
Even if I'm Gone Already in the "Head"....

Taco :o)
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Quoting CycloneOz:


ROFLMAO!!!!! :D What a riot! I love the fat body with the little legs look!!!!


Ya that is perfect for us 4ft 400lbs boys.......LOL
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Good Morning........Lot's of moisture out there in the tropical Atlantic but sheer still hostile out in the MDR......If the moisture around the ITCZ stays there as it lifts up, and, a low SAL forecast holds true, we may well have some monster storms headed towards the Greater Antilles (Eastern Caribbean) down the road in August. Also, the A-B high will shift around between now and August but starting to see some pretty solid ridging/bridging right now between Africa and the Eastern Seabord that would prevent curvature in the mid-Atlantic of any waves that reach storm status in the Central Atlantic on the way "over" to pay us a visit.........That positioning of the A-B high will make all the difference this season in terms of general tracks/impacts during the CV season........
Member Since: August 8, 2006 Posts: 0 Comments: 11089
1142. IKE
Quoting splash3392:
Everyone's been drooling for a system to form.


I don't see much on the 00Z ECMWF either.

You're probably correct.
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I stated early yesterday that we might see a small system just off the North Yucatan as a Low might develop there....but i see nothing on the models.
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Everyone's been drooling for a system to form.
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Quoting Jeff9641:


Yes, I did infact. Saw .51" in 5 minutes with lots of lightning. It's been raining here off and on all morning so far as well.

I thought you had some good storms. I saw one that had it rotating near you. I only had .006 yesterday lots of thunder not much rain.
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1137. IKE
Here's the 00Z CMC @ 144 hours...

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Quoting Jeff9641:
The CMC is model seems to be the most aggressive with this feature early next week nearing Florida.


Jeff what are you looking at.....I see nothing forming on the models.
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1135. IKE
I don't see much either except the GFS.

Here's the 00Z CMC. Nothing much east of Florida.
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Quoting splash3392:
Tampa, dangling a carrot! Be careful what you attract!


Nope not dangling nothing..just stated a fact!
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Quoting Jeff9641:
All the computer models are developing a low near Bermuda and moving it toward the Florida's east coast by next week. Interesting!! I was thinking I was seeing things this morning on the models and had to look again!


I just looked at most models.....I don't see that! What models are you looking at.

Computer models
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1130. Ossqss
Quoting Engine2:
My guess is they still have fear about the European market - specifically the fiscal crisis in Greece


Yup, and Spain and Portugal and Italy and a complete distrust of one another due to the huge government debt they cannot pay back, and a little bit of the China housing bubble, and France talking of breaking out on their own and significant devaluation of the Euro and flight to safety in Gold and US bonds also. It looks like a rough day in the USA.

OZ, still working on the Ozosphere :)

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Tampa, dangling a carrot! Be careful what you attract!
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Quoting CycloneOz:


Our little communications systems worked pretty well. Those of you who could not listen to tornadodude's live broadcast missed out on some edge of the seat excitement.

I'm not sure, but I believe XtremeHurricanes.com is now the first severe storm website to have live broadcast a team near severe weather, with a spotter live on line, and audience participation in the chase.

You should have been there. The chat room was busy, with knowledgeable viewers who were actually contributing to the ground team's chase. I was amazed at how wonderfully all the technology worked.

When tornadodude gets a working web cam with cell phone connectivity, he should be able to provide you with some awesome moments online.

Yesterday, he proved himself as a budding meteorological star.

Stay tuned for his WU updates! If he goes live, you do not want to miss out again! :)


Good Morning All,

No I hope not to miss it either. I sure was impressed with how well it went. OZ you had him right where he needed to be. I just hope there is something for me to chase when we get up there on the 23rd. I have moved our trip up by 1 day to get up there. Driving all day on the 22nd. Man I'm looking forward to it...

Taco :o)
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Quoting severstorm:

What causing them to go nuts like that?


Sorry i stepped away. The drop of the Euro is partly the blame but the Asian Markets are dropping primairly on the increase of inflation as the Gov. will increase the lending rate. Inflation will also be the US next problem looming.
Also, anyone traveling to Eurp. now would be the time to go as the you can get about 1.24 Euro. for $1.00 US currency. Nice!
The US was considering buying into the Euro with Tax payer dollars. That would be a serious mistake as that would cause and Euro to raise and give the US dollar less power driving inflation higher into the US. Big misatake to do that IMO!

Enough about this. We might just have some action coming into the Tropics late this week!
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Very beautiful garden indeed, wish i had that green thumb ALMOST everything i plant dies lol
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I'll be in Greece the end of August if its still there!
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Quoting Engine2:
My guess is they still have fear about the European market - specifically the fiscal crisis in Greece

Thanks
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Dr. Masters co-founded wunderground in 1995. He flew with the NOAA Hurricane Hunters from 1986-1990. Co-blogging with him: Bob Henson, @bhensonweather

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