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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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.

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From the other blog....

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....


Quoting Weather456:


The Lesser Antilles is highest risk area of the 2010 Atlantic Hurricane Season. We lie in the warmest waters, lowest pressures, wettest conditions and just south of the subtropical ridge. It seriously does look good for us 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...
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At 830pm a Waterspout was reported West of the 24 Mile Lake Pontchartrain Causeway Bridge...around the 12 mile Point or mid bridge.

Most Likely the appendage.




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Quoting HaboobsRsweet:


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).


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.
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Quoting Bordonaro:

Good evening Pottery, how much rain did you receive today?

Me? Not a dam drop. But some showers in north of the island. Not much, I hear. Still expectin'....
Member Since: October 24, 2005 Posts: 0 Comments: 24379
214. viman
Will anyone be attending the 2010 Governor's Hurricane Conference in Fort Lauderdale? or more like has anyone ever attended one of these?

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/
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213. xcool
thank i try alot
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Quoting Weather456:


Your intensity is reasonable. The subtropical jet stream will rip anything apart trying to move in that direction.
Yeah, I'm calling May 24th, and it's max intensity is going to be 50 MPH.
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Well I'm thinking more of the 29thor 30th for our 1st storm this season....

Taco :o)
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Quoting pottery:

And I am saying may 21.

Good evening Pottery, how much rain did you receive today?
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Quoting SouthALWX:
since when does the gulf stream reverse 0.o I mean ... I know we're getting close to 2012 but ....
Yeah I think he is a little nuts.
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Despite the recent loss of convection in the past few hours, it is still quite impressive to see this nice of an upper anticyclone in May settled right over a tropical wave with this much pronounced mid-level turning. It's really something to see.

High-resolution Water-vapor Loop

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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.




Your intensity is reasonable. The subtropical jet stream will rip anything apart trying to move in that direction.
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Doc, are ya gonna join us this year ? It is your web site and blog!

Season is upon us........



Please join us !

Atlantic Season Contest - Now Open




Member Since: June 12, 2005 Posts: 6 Comments: 8186
Quoting SouthALWX:
since when does the gulf stream reverse 0.o I mean ... I know we're getting close to 2012 but ....

Yeah!! I asked that a few mins ago too. That's a new one to me.
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Does anyone know if Cyclone Oz found anything in W TX today, besides lots of rain?
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Way to GO xcool. And we posted at the same time too!
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Quoting MiamiHurricanes09:
I think our first system will develop on May 24th, I'm calling it! lol.


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).
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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:

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200. xcool
may 21 here .
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since when does the gulf stream reverse 0.o I mean ... I know we're getting close to 2012 but ....
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Quoting MiamiHurricanes09:
I think our first system will develop on May 24th, I'm calling it! lol.

And I am saying may 21.
Member Since: October 24, 2005 Posts: 0 Comments: 24379
Quoting HaboobsRsweet:


I agree, the first couple will probably be in the caribean but I do not think it is going to be as fast as people are thinking. Mid June for sure but not seeing a May storm. I am getting all of my stuff ready next week for this season.
I think our first system will develop on May 24th, I'm calling it! lol.
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Quoting Chicklit:
Am going to get serious about hurricane preparedness in a couple of weeks...after I finish my garden projects and paint the carport slab. Our first storms will be in the Caribbean so you all should be getting ready now.


I agree, the first couple will probably be in the caribean but I do not think it is going to be as fast as people are thinking. Mid June for sure but not seeing a May storm. I am getting all of my stuff ready next week for this season.
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From the 8 pm NHC report: TROPICAL WAVE IS ALONG 57W FROM 2N-10N. THE WAVE EXTENDS INLAND
OVER SURINAME AND IS MOVING WEST AT 15 KT. THE GFS MODEL DISTINCTLY DEPICTS THIS WAVE AT 850 MB. WIDELY SCATTERED MODERATE CONVECTION IS FROM 4N-7N BETWEEN 54W-58W.
Hopefully this will bring rain. Obviously a scattered mess. Anyway, goodnight and let's hope for the best and prepare for the worst.

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Quoting Skyepony:


Yeah no certainty.. just commenting how huge the C ATL blob is. The global view you posted has the whole thing were Pat's about cuts it in 1/2.. does look like a memorable season ahead.




I'm not seeing this weak TS on the GFS.. there is some 850vort but nothing on the sea level pressure.. no low no TS.. though does look like this wave may enhance that front tail end as it comes off the Yucatan.
Agreed.
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Quoting GNDcanewatcher:
Good evening all - I have a oil spill / weather related question:
My brother has informed me that in August the oil spill could make its way down to the south eastern Caribbean theatening the whole of the Lesser Antillies because of the reversal of the Gulf Stream. I know this is a long way out and highly suspect question when the real area of concern isn't near here, but I thought it might be useful for all of the Caribbean community to become more aware of this problem and to know at least to be prepared somewhat for it if it is, so - How likely is it that we will be facing consequences all the way down here come August / September?


That is a good question. I assume it is hard to tell because it all depends on the wind pattern and how it is pushed into the different currents. Also it depands on whether or not they can cut off some of the flow. They are cleaning up a lot of oil per day but more is coming out faster than they can clean.
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Quoting GNDcanewatcher:
Good evening all - I have a oil spill / weather related question:
My brother has informed me that in August the oil spill could make its way down to the south eastern Caribbean theatening the whole of the Lesser Antillies because of the reversal of the Gulf Stream. I know this is a long way out and highly suspect question when the real area of concern isn't near here, but I thought it might be useful for all of the Caribbean community to become more aware of this problem and to know at least to be prepared somewhat for it if it is, so - How likely is it that we will be facing consequences all the way down here come August / September?

The reversal of the Gulf Stream ??
Member Since: October 24, 2005 Posts: 0 Comments: 24379
Quoting pottery:

The way things are going/changing, I would not be too surprised to see one next week.
Possibly. I'm thinking since the ECMWF is showing ridging occurring over the eastern seaboard on May 24th if matched with a good upward motion MJO we could have some development.
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321
WFUS54 KLIX 160107
TORLIX
MSC045-047-160130-
/O.NEW.KLIX.TO.W.0015.100516T0107Z-100516T0130Z/

BULLETIN - EAS ACTIVATION REQUESTED
TORNADO WARNING
NATIONAL WEATHER SERVICE NEW ORLEANS LA
807 PM CDT SAT MAY 15 2010

THE NATIONAL WEATHER SERVICE IN NEW ORLEANS HAS ISSUED A

* TORNADO WARNING FOR...
EAST CENTRAL HANCOCK COUNTY IN SOUTHERN MISSISSIPPI...
THIS INCLUDES THE CITIES OF...WAVELAND...DIAMONDHEAD...BAY ST.
LOUIS...
SOUTHWESTERN HARRISON COUNTY IN SOUTHERN MISSISSIPPI...

* UNTIL 830 PM CDT

* AT 801 PM CDT...NATIONAL WEATHER SERVICE METEOROLOGISTS DETECTED
A SEVERE THUNDERSTORM CAPABLE OF PRODUCING A WATERSPOUT WITH
STRONG ROTATION JUST OFF THE COAST NEAR WAVELAND... MOVING NORTH
AT 20 MPH. THIS WATERSPOUT WILL LIKELY MOVE ONSHORE NEAR BAY ST
LOUIS.

* THE TORNADO WILL BE NEAR...
BAY ST. LOUIS BY 815 PM CDT...
DIAMONDHEAD BY 825 PM CDT...

PRECAUTIONARY/PREPAREDNESS ACTIONS...

THE SAFEST PLACE TO BE DURING A TORNADO IS UNDER A WORKBENCH OR OTHER
PIECE OF STURDY FURNITURE. SEEK SHELTER ON THE LOWEST FLOOR OF THE
BUILDING IN AN INTERIOR HALLWAY OR ROOM SUCH AS A CLOSET. USE
BLANKETS OR PILLOWS TO COVER YOUR BODY AND ALWAYS STAY AWAY FROM
WINDOWS.

IF IN MOBILE HOMES OR VEHICLES...EVACUATE THEM AND GET INSIDE A
SUBSTANTIAL SHELTER. IF NO SHELTER IS AVAILABLE...LIE FLAT IN THE
NEAREST DITCH OR OTHER LOW SPOT AND COVER YOUR HEAD WITH YOUR HANDS.

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Am going to get serious about hurricane preparedness in a couple of weeks...after I finish my garden projects and paint the carport slab. Our first storms will be in the Caribbean so you all should be getting ready now.
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Good evening all - I have a oil spill / weather related question:
My brother has informed me that in August the oil spill could make its way down to the south eastern Caribbean theatening the whole of the Lesser Antillies because of the reversal of the Gulf Stream. I know this is a long way out and highly suspect question when the real area of concern isn't near here, but I thought it might be useful for all of the Caribbean community to become more aware of this problem and to know at least to be prepared somewhat for it if it is, so - How likely is it that we will be facing consequences all the way down here come August / September?
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Wow that cell in the Gulf and tracking over southern MS produced a waterspout that moved on land. Doesnt even look that impressive and talked to some folks that live out there and said it is a weak TS. Interesting.
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186. Skyepony (Mod)
Quoting MiamiHurricanes09:
Well I still can't be sure about that, but I can say one thing. We will have a lot of tropical waves, then you have the low SAL and the record SSTs. I'm sure we'll have a lot of Cape Verde systems, but I don't know if they will be big when they emerge.


Yeah no certainty.. just commenting how huge the C ATL blob is. The global view you posted has the whole thing were Pat's about cuts it in 1/2.. does look like a memorable season ahead.


Quoting CybrTeddy:
Imo, this wave might be the wave that the GFS predicts develops into a weak TS around Tuesday.. emerges from South America and develops in the W Caribbean.


I'm not seeing this weak TS on the GFS.. there is some 850vort but nothing on the sea level pressure.. no low no TS.. though does look like this wave may enhance that front tail end as it comes off the Yucatan.
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Well; gonna clean the gear for an am fishing trip with the kids......See Yall on Monday.
Member Since: August 8, 2006 Posts: 0 Comments: 9213
I think our first system will develop in May in the Caribbean. I made a track showing where I think it'll go.


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183. xcool



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The way things are going I do not expect to see the first tropical event in the atlantic or carb until late june. Needs a little more time to set everything up. Once it happens we will see many storms back to back.
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I am not a betting man but with the "leftover" southern jog of lows still coming out of Texas into the Gulf, I will "guess" that the first one will be a frontal remnant in the Gulf if the sheer drops down enough by the end of May...But, don't quote me on it.... :)
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Quoting MiamiHurricanes09:
I think we will see one in the Caribbean before June 1st.

The way things are going/changing, I would not be too surprised to see one next week.
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179. xcool


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TROPICAL WAVE IS ALONG 57W FROM 2N-10N. THE WAVE EXTENDS INLAND
OVER SURINAME AND IS MOVING WEST AT 15 KT. THE GFS MODEL
DISTINCTLY DEPICTS THIS WAVE AT 850 MB. WIDELY SCATTERED
MODERATE CONVECTION IS FROM 4N-7N BETWEEN 54W-58W.
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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.


Good evening, folks. Thanks for more news about why this is going to be an active season, Doc!
The SSTs between Africa and the Caribbean are now as high as we normally see in July...(!)

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We had 90L and 91L before June 1 09,so I give the odds this year now, at 50/50 before June 1.

Memorial weekend last year flooded The Daytona area.


Residents uses boats to navigate along South Keech Street in Daytona Beach, Fla. on Thursday May 21, 2009. Three elementary and middle schools were closed in Daytona Beach Thursday due to access problems from the flooding, and Daytona State College closed for classes due to the flooding on its campuses. A shelter was opened at a church for residents needing to leave their homes. (AP Photo/Daytona Beach News Journal, Peter Bauer)
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Quoting weathermanwannabe:
Evening....Quick spot check.....Record April SST's in the MDR; like July?.....Probably a record May too then "pop" as soon as the sheer drops....Gulf and approach of the wave to the Antilles in mid-May light up like a Christmas tree on the rainbow loops; not a good sign at all....Who knows where the first bona-fide Atlanbtic basin storm will pop up......Dr. M may be right....We could see one before June 1st.
I think we will see one in the Caribbean before June 1st.
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Evening....Quick spot check.....Record April SST's in the MDR; like July?.....Probably a record May too then "pop" as soon as the sheer drops....Gulf and approach of the wave to the Antilles in mid-May light up like a Christmas tree on the rainbow loops; not a good sign at all....Who knows where the first bona-fide Atlanbtic basin storm will pop up......Dr. M may be right....We could see one before June 1st.
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Quoting Skyepony:
MiamiHurricanes09~ That shows the one possible saving factor, as far as numbers, for the season..Maybe we'll see one of those years that the storms are so large they have a tough time pulling together before they hit land.
Well I still can't be sure about that, but I can say one thing. We will have a lot of tropical waves, then you have the low SAL and the record SSTs. I'm sure we'll have a lot of Cape Verde systems, but I don't know if they will be big when they emerge.
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i was just watching the webcam at the iceland volcano, it really looks as though it has spewed ash all day. all of the sudden there were 3 girls standing in front the webcam waving. it was on this one.

http://eldgos.mila.is/eyjafjallajokull-fra-thorolfsfelli/
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170. Skyepony (Mod)
MiamiHurricanes09~ That shows the one possible saving factor, as far as numbers, for the season..Maybe we'll see one of those years that the storms are so large they have a tough time pulling together before they hit land.
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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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