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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Yo estoy bien pero el susto fue grande en la cama ya que se movio bastante.

I am fine but the bed shaked a good deal and I was awaken.I am in San Juan.
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Lucky it was pretty deep or else you would of felt it a lot more and it could of caused damage.
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517. JRRP

ahora si
see you tomorrow
Link
Member Since: August 16, 2007 Posts: 0 Comments: 5490
516. Prgal
Hello everyone. What a shake. We felt it too here in Carolina, PR.
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515. JLPR
Quoting doabarrelroll:


good. I am glad. earthquakes are spooky


Yes they are, I didn't really resister that my bed was shaking and just stared at my TV and closet door moving :P
Once it was over I was like, ''oh! that was an earthquake!'' XD
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512. JLPR
Quoting doabarrelroll:


estas bien?


todo bien :)
we are just a little nervous XD
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510. JRRP
Quoting JLPR:


Yep, fue en el Canal de la Mona, entre Puerto Rico y Santo Domingo, ustedes all tienen que haber sentido algo tambin.

si asi es
pense que el sueo me tenia algo loco y me iba de lado
luego escuche el monitor como si estuviera temblando
Member Since: August 16, 2007 Posts: 0 Comments: 5490
509. JRRP

Quoting Hurakantaino:
JRRP, se sintio tambien in the NW, Aguadilla, pretty strong.

bueeeeno espero que no haya habido daños muy graves
Member Since: August 16, 2007 Posts: 0 Comments: 5490
506. JLPR
Quoting SouthALWX:
lol you guys okay? I was proud of myself .. never took a single spanish lesson but I was able to deduce it was an earth quake. Or that he was having a bad trip of some kind.


haha! Good for you :3
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505. JLPR
Quoting JRRP:

estoy en santo domingo y senti algo tambien
mi monitor se movio


Yep, fue en el Canal de la Mona, entre Puerto Rico y Santo Domingo, ustedes allá tienen que haber sentido algo también.
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JRRP, se sintio tambien in the NW, Aguadilla, pretty strong.
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lol you guys okay? I was proud of myself .. never took a single spanish lesson but I was able to deduce it was an earth quake. Or that he was having a bad trip of some kind.
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502. JRRP
Quoting JLPR:


that's called panic mode xD

estoy en santo domingo y senti algo tambien
mi monitor se movio
Member Since: August 16, 2007 Posts: 0 Comments: 5490
501. JLPR
16-MAY-2010 05:16:10 18.30 -67.07 5.7 110.1 MONA PASSAGE

decent 5.7, it was felt all the way to Ponce, the south of the island and I felt it here in the northeast
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wow 5.7 in the mona passage
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499. JRRP
Quoting Hurakantaino:
Alguien en PR, me puede decir cuanto fue en la escal ritcher.

5.7
Member Since: August 16, 2007 Posts: 0 Comments: 5490
498. JRRP
Member Since: August 16, 2007 Posts: 0 Comments: 5490
yes that's the advantage of speaking more than one language and this concern us because the earthquake was in Puerto Rico
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496. JLPR
Quoting SouthALWX:
when folks drop into native tongue on an otherwise english forum, you know it's hitting the fan in some form or another.


that's called panic mode xD
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495. JLPR
Quoting Hurakantaino:
Alguien en PR, me puede decir cuanto fue en la escal ritcher.


No idea T_T
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Alguien en PR, me puede decir cuanto fue en la escal ritcher.
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when folks drop into native tongue on an otherwise english forum, you know it's hitting the fan in some form or another.
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492. JLPR
well just experienced a little earthquake :\
a few things moved from side to side but thankfully it wasn't that strong, I wonder what number in the scale it was :|
It certainly woke me up T_T
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491. xcool
HurricaneTrack.com The 00Z GFS, just coming out now, indicates the possibility of tropical cyclone development in the SW Caribbean in just a little over a week. This would coincide with a predicted more favorable upward motion pattern as well. We'll have to see other major computer models come on board before putting too much in to this
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You just had an earthquake in Puerto Rico,don't know the detailts but quite strong.
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489. xcool



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Someone may have posted this already but there is an awful story in the New York Times:

Giant Plumes of Oil Found Under Gulf of Mexico

Scientists find giant oil plumes under Gulf
One is about 10 miles long, 3 miles wide and 300 feet thick

updated 6:04 p.m. PT, Sat., May 15, 2010

NEW YORK - Scientists are finding enormous oil plumes in the deep waters of the Gulf of Mexico, including one as large as 10 miles long, 3 miles wide and 300 feet thick. The discovery is fresh evidence that the leak from the broken undersea well could be substantially worse than estimates that the government and BP have given.

Article may be found here:

Link


I have for some time suspected this was a LOT worse than we were hearing ... still waiting for an ROV shot of that bent riser. Again, I believe there is a good reason we are not seeing it.

Do read the article. The plumes are deep and are raising concerns about oxygen depletion in the Gulf.

ugh

WTO
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487. xcool
LOL
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486. JRRP
mi monitor se movio
Member Since: August 16, 2007 Posts: 0 Comments: 5490
485. JRRP
ahora mismo
Member Since: August 16, 2007 Posts: 0 Comments: 5490
484. JRRP
acabo de sentir un temblor de tierra
Member Since: August 16, 2007 Posts: 0 Comments: 5490
Quoting SouthALWX:
@Levi
would not TC's tracking over a same general area generate the lower anomalies in HINDSIGHT? I see what 456 is trying to do, and that is test the accuracy of the models and see if the negative anomalies have in the past corresponded with increased TC activity, in order to see if it is a valid forecast tool.


I see your point. Yes hurricanes affect the overall MSLP anomalies, to some extent, but they are not nearly all of it. Most of the low MSLP anomalies you see are pattern-generated, and are usually responsible for tropical storm formations in the first place. You are not as likely to get a congregation of storm formations/tracks in a certain area that cause negative MSLP anomalies than you are to get a congregation of formations/tracks caused by already existing negative MSLP anomalies.

The other thing is that when you have a nice swatch of low pressures across the western Atlantic, such as in 2004 or on the Euro forecast for this year, you still only usually get the tracks mostly from the center to the south of the axis of lowest pressure. You don't get as many tracks on the northern (right) side. If the hurricanes were causing the low pressures, you would expect to see them fairly evenly distributed about the center-axis of lowest pressure. Instead we see a weighted track bias to the south of the low pressure swath. The reasons for this are what I mentioned earlier, that the south side of the swatch is where trade winds are slowed, allowing more surface convergence.
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After reading Dr. Master's blog entry, I was interested in the second huge factor of this season's hurricane outlook: strength of the El Nino. Can anyone cite or comment about this years El Nino outlook, please?
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@Levi
would not TC's tracking over a same general area generate the lower anomalies in HINDSIGHT? I see what 456 is trying to do, and that is test the accuracy of the models and see if the negative anomalies have in the past corresponded with increased TC activity, in order to see if it is a valid forecast tool.
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The E volcano is off the chain, for lack of a better expression.
Member Since: August 18, 2008 Posts: 0 Comments: 3112
478. JRRP
see you tomorrow
Member Since: August 16, 2007 Posts: 0 Comments: 5490
477. xcool
no zzz. BUZZZZZ
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ZZZZZZZZZZZZZZ.....
Member Since: July 15, 2006 Posts: 169 Comments: 53308
i LIVE IN fLA PNAHNDLE AREA...ANY THOUGHTS ON POSSIBLE HURRICANES AFFECTING MY AREA???
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474. xcool
. I'm waiting on new computer models data....
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Quoting kmanislander:
Hi Pottery

Earlier today it looked like you were going to be swamped. Not so much anymore.




Yeah. Was waiting on it all day. Not a drop here, although some in the North.
I'm out........
Member Since: October 24, 2005 Posts: 0 Comments: 24142
I'm out as well. Back tomorrow
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Hi Pottery

Earlier today it looked like you were going to be swamped. Not so much anymore.



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Latest ASCAT pass caught the tropical wave, and is only 2 hours old now. Still no significant surface reflection. All the rotation is in the mid-levels.

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It is Sunday morning.
I am going to sleep.
See you all later.
Member Since: October 24, 2005 Posts: 0 Comments: 24142

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

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