Record Atlantic SSTs continue in the hurricane Main Development Region
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
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 | 27 — Blog Index
Haha I have been wrong before but I think the synoptic pattern needs to just shift a little more northward and that doesnt happen overnight. Also the Gulf needs to warm just a little more, it is warming fast but still needs a couple more weeks. I am thinking mid June and we will see this blog fire up with our first storm. (blog probably go nuts before that trying to make all of this little waves hurricanes).
Yeah!! I asked that a few mins ago too. That's a new one to me.
Season is upon us........
Please join us !
Atlantic Season Contest - Now Open
Your intensity is reasonable. The subtropical jet stream will rip anything apart trying to move in that direction.
High-resolution Water-vapor Loop
Good evening Pottery, how much rain did you receive today?
Taco :o)
Just curious, I'm scheduled to attend and I've never been to any.
I've visited the website and it seems like it's going to be pretty cool, I hope we get a tour of the Hurricane Center.
http://www.flghc.org/
Me? Not a dam drop. But some showers in north of the island. Not much, I hear. Still expectin'....
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.
Most Likely the appendage.
1866. BahaHurican 8:51 PM EDT on May 15, 2010
Evening all.
Quoting StormJunkie:
Afternoon all...
I see we've already broken out the HeRbert boxes...lol
IMO, it's the best time TO break 'em out... lol.... before they can do any real damage.... lol
Would like to say it's good to see so many of the "oldtimers" joining in early this year....
I think everyone along the traditional track from SE of Hebert Box #1 to Carolinas needs to be extra alert this year. Tracks across the NE Caribbean and along the N of the Antilles towards The Bahamas and FL seem fairly likely, especially if that high you modeled doesn't extend all the way into the GOM...
That's what I said, though I didn't think it was too plausible.
~X~
Seems like they added real-time FLIR. :)
Link
~X~
Maybe as the D-Max occurs in the morning, convection should increase, as the wave moves west at 15KT.
Your point is well taken.
It is a difficult call, because these are, frankly, unprecedented conditions now.
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)
Exactly my point lol
No probs, GND.
By the way, I am in Trini.
~X~
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.
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
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)
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
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.
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!
yea, lurking
what? which one? can you post link?
hi bord!
Viewing: 201 - 251
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 | 27 — Blog Index