Record Atlantic SSTs continue in the hurricane Main Development Region

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

Share this Blog
7
+

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

Reader Comments

Comments will take a few seconds to appear.

Post Your Comments

Please sign in to post comments.

or Join

Not only will you be able to leave comments on this blog, but you'll also have the ability to upload and share your photos in our Wunder Photos section.

Display: 0, 50, 100, 200 Sort: Newest First - Order Posted

Viewing: 269 - 219

Page: 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 | 26 | 27Blog Index

Member Since: Posts: Comments:
Quoting Xyrus:
Link

What I mistook for a possible lava river now appears to be a "crack" in the mountain (I can only see it on the FLIR), which seems to be emitting steam.

~X~

That crack is a crevasse in the glacier's face. Occasionally "E" shoots out a pretty good steam cloud from that vent.
Member Since: August 25, 2009 Posts: 20 Comments: 6785
next update at 1203 am
Member Since: July 15, 2006 Posts: 175 Comments: 54858
BIG PICTURE

here is full north hemisphere water vapour sat image as of 903 pm



Member Since: July 15, 2006 Posts: 175 Comments: 54858
Member Since: Posts: Comments:
Quoting pottery:

Thanks for the plug!
heheheheh


I think your property value just went up :)
Member Since: Posts: Comments:
Quoting StormW:


When I get the chance, I'll try to send it...I have a daily summary of it in my blog posts archives.


Kool.
Member Since: Posts: Comments:
262. Xyrus
Link

What I mistook for a possible lava river now appears to be a "crack" in the mountain (I can only see it on the FLIR), which seems to be emitting steam.

~X~
Member Since: Posts: Comments:
Quoting MiamiHurricanes09:
I see what you're talking about, but it isn't TS strength. I also don't think it is the same wave.

GFS 18z 66 Hours - Notice the 1011 MB surface low just east of Belize.





Was a TS in an earlier run.. looks like it dropped it nearly. Gotta have consistency.
Member Since: Posts: Comments:
Quoting GNDcanewatcher:
I should have assessed the assumptions I was making in my first question; I don't know that enough about ocean currents to assume what I'm told is true. Trinidad is one of the coolest places in the world in my opinion.

Thanks for the plug!
heheheheh
Member Since: October 24, 2005 Posts: 0 Comments: 24653
Quoting WaterWitch11:


what? which one? can you post link?
hi bord!

Good evening Water. There are two links below. The HVO/POR link shows 2 separate views of the eruption. Mulakot cam shows several pics around the "E" volcano, but you have to refresh to updates pics.

Mulakot web-cam: Link

HVO/POR link:Link

Recent Mulakot shot:
Member Since: August 25, 2009 Posts: 20 Comments: 6785
Quoting KEEPEROFTHEGATE:
there is a strong blob within the ITCZ se of wave reflection this as it moves into coastal sa may bring heavy tropical rainshowers as it moves on shore later tomorrow morning

Yeah, I see that. But as long as that dominant upperlevel wind is doing what it's doing, and if it remains where it is now, I think that the convection will get blown to the NE.
Member Since: October 24, 2005 Posts: 0 Comments: 24653
Quoting StormW:


Don't remember if I told ya...I got to go to the National Hurricane Conference back in March


lol. I wasn't anywhere near the blogs in March but that is great news to hear. Feel free to link me anything you may have learned there that I would need to know. Learned alot from you over the past few years.
Member Since: Posts: Comments:
I should have assessed the assumptions I was making in my first question; I don't know that enough about ocean currents to assume what I'm told is true. Trinidad is one of the coolest places in the world in my opinion.
Member Since: Posts: Comments:
Quoting GNDcanewatcher:
as a result of the comments about my competency, my next question is: does the flow of the Gulf Stream change in the course of the year?

it may vary slightly but the overall current remains unchanged year-round
Member Since: Posts: Comments:
Quoting pottery:

That shows, very nicely, what kept the rain away from Trinidad today.
Very strong upper-level winds blowing the stuff off to the NorthEast, as fast as it came in from the East and southeast.
Great stuff!
there is a strong blob within the ITCZ se of wave reflection this as it moves into coastal sa may bring heavy tropical rainshowers as it moves on shore later tomorrow morning
Member Since: July 15, 2006 Posts: 175 Comments: 54858
Quoting Xyrus:
Lava spurts and lightning occasionally too.

I caught a few glimpses of those infamous lava bombs, but no lightning tonight.

On Wed night, "E" was throwing out massive lava bombs, plus I seen several vivid lightning flashes.
Member Since: August 25, 2009 Posts: 20 Comments: 6785
Quoting Bordonaro:
Looks like our friendly "E" Volcano is really angry at Iceland, she is shooting out one large plume of ash. Pic below off the Mulakot web-cam a few minutes ago:



what? which one? can you post link?
hi bord!
Member Since: August 11, 2008 Posts: 3 Comments: 1681
Quoting StormW:
456, you around?


yea, lurking
Member Since: Posts: Comments:
Quoting KEEPEROFTHEGATE:
nw atlantic basin

That shows, very nicely, what kept the rain away from Trinidad today.
Very strong upper-level winds blowing the stuff off to the NorthEast, as fast as it came in from the East and southeast.
Great stuff!
Member Since: October 24, 2005 Posts: 0 Comments: 24653
Quoting reedzone:
I

I wont forget our pesky 97L invest last year. Before it got to the islands, even the NHC dropped it, but I said "wait till the morning." The next morning, 97L almost became a TD.

Almost only counts in horseshoes...this wave will be another almost. There just is not enough support yet for it to sustain itself and become a tropical anything other than a wave. I am going to enjoy the next 2-3 weeks of people trying to create tropical systems. As Levi and I stated, just look at the big picture, it is not ready for tropical events. yes I could be wrong but just what I think and id put money on it if it was legal.
Member Since: Posts: Comments:
Quoting FLWeatherFreak91:
What do you think would account for the very southerly turn to the east? Steering this time of year favors storms making it further north.
Well the few models that develop a system in that area curve it towards SWFL so I decided to go with that.
Member Since: Posts: Comments:
244. Skyepony (Mod)
Latest horizonal current..
Member Since: August 10, 2005 Posts: 193 Comments: 38684
nw atlantic basin
Member Since: July 15, 2006 Posts: 175 Comments: 54858
242. Xyrus
Lava spurts and lightning occasionally too.
Member Since: Posts: Comments:
Quoting Xyrus:


Seems like they added real-time FLIR. :)

Link

~X~

The FLIR camera has been there for a couple of weeks, at least. The camera is a nice addition, but it cannot pick up heat signatures when the fog and low clouds roll in.

The scientists are throwing up red flags on 3 other Icelandic volcanoes, link to article below:

Link
Member Since: August 25, 2009 Posts: 20 Comments: 6785
Quoting GNDcanewatcher:
oh well, oops. I'm not a earth scientist, just an English teacher.


Its ok, you have to be real careful how you say things in here thats all....

I hope I was able to help though....

Taco :o)
Member Since: Posts: Comments:
Gulf Of Mexico - Funktop Color Infrared Loop
Member Since: July 3, 2005 Posts: 426 Comments: 129093
San Diego residents are reporting shaking continuing in the area. The shaking, according to the USGS, is likely due to the Easter quake this year which rocked the region.

Twitter is rolling with reports of rainbow cloud over Los Angeles today. Reports are coming in that this looks similar to before both the China and Chile quakes where residents reported and took photos of such events in the sky.

While no one can be sure what it means, people should always be prepared for a major Earthquake in Southern California as it is seismically activity

from May 13th
Member Since: August 11, 2008 Posts: 3 Comments: 1681
Quoting reedzone:
I

I wont forget our pesky 93L invest last year. Before it got to the islands, even the NHC dropped it, but I said "wait till the morning." The next morning, 93L almost became a TD.
I remember.
Member Since: Posts: Comments:
Quoting MiamiHurricanes09:
I think our first system will develop in May in the Caribbean. I made a track showing where I think it'll go.


What do you think would account for the very southerly turn to the east? Steering this time of year favors storms making it further north.
Member Since: Posts: Comments:
I
Quoting MiamiHurricanes09:
Yes, it is possible and likely, imo.


I wont forget our pesky 97L invest last year. Before it got to the islands, even the NHC dropped it, but I said "wait till the morning." The next morning, 97L almost became a TD.
Member Since: Posts: Comments:
234. Xyrus
E is popping again. A lava trail has formed going down the mountain facing the webcam. You can see the steam on visual and the river itself on the FLIR.

~X~
Member Since: Posts: Comments:
Quoting GNDcanewatcher:
oh well, oops. I'm not a earth scientist, just an English teacher.

No probs, GND.
By the way, I am in Trini.
Member Since: October 24, 2005 Posts: 0 Comments: 24653
If any of you missed it. I have done my first official blog post. Please feel welcomed to comment on it. 2010 Hurricane Season Blog #1: Outlook
Member Since: Posts: Comments:
oh well, oops. I'm not a earth scientist, just an English teacher.
Member Since: Posts: Comments:
Quoting MiamiHurricanes09:
It should increase in convection in the morning.


Exactly my point lol
Member Since: Posts: Comments:
Quoting GNDcanewatcher:
as a result of the comments about my competency, my next question is: does the flow of the Gulf Stream change in the course of the year?

No but I do want to say this. If the Oil Slick gets into the Gulf Stream
It could go all the way around to the East coast....
Then That would be bad

Taco :o)
Member Since: Posts: Comments:
Quoting reedzone:
Could I say.. Diurnal Minimum?? The wave could blow up later tonight and bring some rains to the islands and SA.
Yes, it is possible and likely, imo.
Member Since: Posts: Comments:
Could I say.. Diurnal Minimum?? The wave could blow up later tonight and bring some rains to the islands and SA.
Member Since: Posts: Comments:
Quoting Bordonaro:

Maybe as the D-Max occurs in the morning, convection should increase, as the wave moves west at 15KT.
It should increase in convection in the morning.
Member Since: Posts: Comments:
Quoting Levi32:


I agree. Based on the model forecasts the subtropical jet is still just a bit far south to give much room in the Caribbean. This wouldn't be so much of a problem except that a system trying to develop off the north coast of Panama would have to wind itself up within the monsoon trough, and that is hard to do and takes time.

Your point is well taken.
It is a difficult call, because these are, frankly, unprecedented conditions now.
Member Since: October 24, 2005 Posts: 0 Comments: 24653
Quoting pottery:

Me? Not a dam drop. But some showers in north of the island. Not much, I hear. Still expectin'....

Maybe as the D-Max occurs in the morning, convection should increase, as the wave moves west at 15KT.
Member Since: August 25, 2009 Posts: 20 Comments: 6785
223. Xyrus
Quoting Bordonaro:
Looks like our friendly "E" Volcano is really angry at Iceland, she is shooting out one large plume of ash. Pic below off the Mulakot web-cam a few minutes ago:



Seems like they added real-time FLIR. :)

Link

~X~
Member Since: Posts: Comments:
Quoting GNDcanewatcher:
as a result of the comments about my competency, my next question is: does the flow of the Gulf Stream change in the course of the year?
No.
Member Since: Posts: Comments:
as a result of the comments about my competency, my next question is: does the flow of the Gulf Stream change in the course of the year?
Member Since: Posts: Comments:
220. Xyrus
Quoting pottery:

And I am saying may 21.


That's what I said, though I didn't think it was too plausible.

~X~
Member Since: Posts: Comments:
Quoting pottery:

Me? Not a dam drop. But some showers in north of the island. Not much, I hear. Still expectin'....
Well you got to keep waiting, and even when it gets to you it isn't going to be major if it continues to lack convection.

Member Since: Posts: Comments:

Viewing: 269 - 219

Page: 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 | 26 | 27Blog Index

Top of Page

About

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

Local Weather

Overcast
45 °F
Overcast