Record warmth in Atlantic Main Development Region for hurricanes

By: Dr. Jeff Masters , 4:52 PM GMT on March 08, 2010

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Sea Surface Temperatures (SSTs) in the Atlantic's Main Development Region for hurricanes were at their highest February level on record last month, 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 region between 10°N and 20°N, between the coast of Africa and Central America, 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.)


Figure 1. The departure of sea surface temperature (SST) from average for March 7, 2010, as derived from the AMSR and AVHRR satellite data. Image credit: NOAA.

SSTs in the Main Development Region (10°N to 20°N and 20°W to 85°W) were an eye-opening 1.02°C above average during February. This easily beats the previous record of 0.83°C set in 1998. SSTs in the Main Development Region are already warmer than they were during June of last year, which is pretty remarkable, considering February is usually the coldest month of the year for SSTs in the North Atlantic. The 1.02°C anomaly is the 6th highest monthly SST anomaly for the MDR on record. The only other months with higher anomalies all occurred during 2005 (April, May, June, July, and September 2005 had anomalies of 1.06°C - 1.23°C).

What is responsible for the high SSTs?
Don't blame El Niño for the high Atlantic SSTs. El Niño is a warming of the Pacific waters near the Equator, and has no direct impact on Atlantic SSTs. Instead, blame the Arctic Oscillation (AO) or its close cousin, the North Atlantic Oscillation (NAO). 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. They are some of the oldest known climate oscillations; seafaring Scandinavians described the pattern several centuries ago. Through east-west oscillation motions of the Icelandic Low and the Azores-Bermuda High, the AO/NAO controls the strength and direction of westerly winds and storm tracks across the North Atlantic. A large difference in the pressure between Iceland and the Azores (positive NAO) leads to increased westerly winds and mild and wet winters in Europe. Positive NAO conditions also cause the Icelandic Low to draw a stronger south-westerly flow of air over eastern North America, preventing Arctic air from plunging southward. In contrast, if the difference in sea-level pressure between Iceland and the Azores is small (negative NAO), westerly winds are suppressed, allowing Arctic air to spill southwards into eastern North America more readily. The winter of 2009 - 2010 has seen the most negative AO and NAO patterns since record keeping began in 1950, which caused a very cold winter in Florida and surrounding states. A negative AO/NAO implies a very weak Azores-Bermuda High, which reduces the trade winds circulating around the High. During December - February, trade winds between Africa and the Lesser Antilles Islands in the hurricane Main Development Region were 1 - 2 m/s (2.2 - 4.5 mph) below average (Figure 2). 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 has heated up significantly, relative to normal, over the winter. This heating is superimposed on the very warm global SSTs we've been seeing over the past decade, leading to the current record warmth. Global and Northern Hemisphere SSTs were the 2nd warmest on record in both December and January.


Figure 2. Sea level pressure averaged for the period December 2009 - February 2010 (left) and the sea level pressure averaged for the period December - February from the long-term mean (1968 - 1998). This winter, the Azores-Bermuda High was about 3 - 4 mb weaker than in a typical winter, due to strongly negative AO/NAO conditions. Image credit: NOAA/ESRL.


Figure 3. Departure of surface wind speed from average for December 2009 - February 2010. Winds were about 1 - 2 m/s (2.2 - 4.5 mph) lower than average over the Atlantic hurricane Main Development Region (MDR). Image credit: NOAA/ESRL.

What does this imply for the coming hurricane season?
According to Dr. Phil Klotzbach of the University of Colorado, February temperatures in the MDR are not strongly correlated with active hurricane seasons. The mathematical correlation between hurricane season Accumulated Cyclone Energy (ACE) and February SSTs is only 0.26, which is considered weak. Past hurricane seasons that had high February SST anomalies include 1998 (0.83°C anomaly), 2007 (0.71°C anomaly), and 1958 (0.68°C anomaly). These three years averaged 13 named storms, 8 hurricanes, and 3 intense hurricanes, which is considerably higher than the average of 10, 6, and 2. The big question is, how long will the strong negative AO/NAO conditions keep the Azores-Bermuda High weak? Well, the AO has risen to near-neutral values over the past week, and the latest 2-week forecast from the GFS model show that the AO and NAO will not be as strongly negative during March. This should allow the Azores-Bermuda High to strengthen some this month and increase the trade winds over the MDR. However, I still expect we'll set a record for warmest-ever March SSTs in the Main Development Region. Longer term, the crystal ball is very fuzzy, as our ability to predict the weather months in advance is poor. The long-range NOAA CFS model is predicting SSTs in the Atlantic MDR will be about 0.70°C above average during the peak months of hurricane season, making it one of the top five warmest years on record--but not as warm as the unbelievable Hurricane Season of 2005, which averaged 0.95°C above normal during August - October. The other big question is, when will El Niño fade? El Niño is currently holding steady at moderate intensity, and I expect that will continue through at least mid-April. It is possible El Niño will linger long enough into the year that it will create increased wind shear that will suppress this year's hurricane season.

Brazilian disturbance
An area of disturbed weather off the coast of Brazil, near 24S 36W, has changed little over the past two days. This disturbance still has a slight potential to develop into subtropical or tropical depression by Wednesday, according to the latest runs of the ECMWF, GFS, and NOGAPS models. Satellite imagery shows little organization to the cloud pattern, and only limited heavy thunderstorm activity. Wind shear over the region is about 20 knots, which is rather high, and should keep any development slow. Sea surface temperatures are about 27°C, about 1°C above average, which is warm enough to support a tropical storm. The system is small, limiting its potential to become a tropical cyclone. I don't think it will become a subtropical depression.

I'll have a new post on Wednesday.
Jeff Masters

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Quoting jeffs713:

I think they would allow calls to 9-1-1. Unless you happened to be driving through a small town in Texas, in which case, you are going to get pulled over, fined, get 3 demerit points, and have your car searched.

Unless you are driving a pickup with a gun rack, in which case they will wave. (The full scenario will never happen, though, those with gun racks don't call 9-1-1)
Member Since: August 16, 2007 Posts: 6 Comments: 12463
Floater page for 90Q
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Quoting AussieStorm:

is it illegal to use a mobile phone while driving there, it is here. $250 fine and 3 demerit point.

I think they would allow calls to 9-1-1. Unless you happened to be driving through a small town in Texas, in which case, you are going to get pulled over, fined, get 3 demerit points, and have your car searched.
Member Since: August 3, 2008 Posts: 16 Comments: 5891
Quoting benirica:
Didnt we recently have a storm slightly strengthen over Florida? I believe what they were saying was since everything was flooded, it wasn't like it was going over land, the storm never got cut off from warm water.
Or maybe I made up the flood part and it was just the swamps...
The point is it fed from the water that was on land. Or so they said.


Tropical Storm Fay and its was the Everglades and Lake Okeechobee.
Member Since: August 11, 2008 Posts: 0 Comments: 2315
Quoting atmoaggie:

Was it Fay that strengthened over the swamp in 2008?


Yes... and Katrina strengthened over the 'Glades as well...
Member Since: June 20, 2005 Posts: 22 Comments: 1054
Dvorak estimates from SAB and TAFB on 90Q:


SL 90 201003091145 3030S 4820W TAFB 1515 ///// ST1.5
SL 90 201003091145 3060S 4800W SAB 1515 ///// ST1.5
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Quoting StormW:


Now ain't that something...wonder if I can get rich by operator error.


I dunno.... Lemme put a sharp chisel through my foot and see what I can collect?
Member Since: June 20, 2005 Posts: 22 Comments: 1054
March Maddness in College Basketball is coming upon us next week. Yeppie. I would like to have a fundraiser Charity for PortLight to be used as a slush fund for people in need of this upcoming season as all indications are this might be a rough season.

I will setup a Challenge for everyone to pick there games automatically through one of the major sites. I would love to raise $1000 dollars with $250 to go the winner as a donation from a 25% return. What i will do is start a receiding account to start at $1000 and when we reach the total it closes. Simply put if one person donates $1000 then only that 1 person will win. So the more you donate the least players will be and the higher chance of getting a donation back. Let me know through WU email you alls thoughts and interest. I have tried these before with just a few playing.

To make it fun for many.....If you cannot donate you can still play but, just not get a dontation back. That way no one is left out that just can't afford to donate as we all know how tuff things are.
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Quoting doabarrelroll:


Thanks! I remember someone onthis blog saying that Hurricanes over Florida take the longest to weaken and he had a link to a chart. I guess that answers my question

Was it Fay that strengthened over the swamp in 2008?
Member Since: August 16, 2007 Posts: 6 Comments: 12463
Didnt we recently have a storm slightly strengthen over Florida? I believe what they were saying was since everything was flooded, it wasn't like it was going over land, the storm never got cut off from warm water.
Or maybe I made up the flood part and it was just the swamps...
The point is it fed from the water that was on land. Or so they said.
Member Since: Posts: Comments:
Excerpt from South America Synoptic Discussion from HPC.

DEEP CONVECTIVE CELLS ARE STARTING TO WRAP AROUND THIS LOW AND MOVING TOWARDS THE CENTER CORE AS THIS SYSTEM CONTINUES TO SUSTAIN A WARM CORE CYCLONE AT LOW LEVELS OF THE ATMOSPHERE. IF VERTICAL WIND SHEAR SUBSIDES...THIS SYSTEM COULD EVOLVE INTO A TROPICAL CYCLONE. SATELLITE DERIVED WINDS SHOW SPEEDS OF 30-35KT ON THE SOUTHERN PERIPHERY OF THE LOW...SUGGESTING TROPICAL STORM STRENGTH AS A MINIMUM.


Latest update on 90Q.

SL 90 2010030912 BEST 0 305S 482W 30 1005 LO
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Tornado tears houses to pieces in Oklahoma
Member Since: August 11, 2008 Posts: 0 Comments: 2315
And, in other crazy news...

Man awarded $1.5 million in lawsuit over table saw accident.

Wow... a saw that cuts... Who knew?
Member Since: June 20, 2005 Posts: 22 Comments: 1054
Quoting severstorm:

Morning all, Now this is much better. Weird storms in texas and kansas last night. Did anybody see the video on the wc of the nado in kansas and the temp was like 52.




This weather station has had false readings for awhile. Most temps are in the mid-upper 50s
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Quoting P451:
A little off topic, but...

What is so hard to understand here? What is wrong with these people? TURN THE CAR OFF.

-problem solved-

Link to image


What are these people doing? TURN THE DAMN KEY TO OFF.


lol?

It can't just be me....



I know this stuff is common sense, but 85% of the United States doesnt have common sense or we wouldnt be in the mess where in right now.
Member Since: August 11, 2008 Posts: 0 Comments: 2315
looks like levi got his system second system ever in southern atlantic
Member Since: July 15, 2006 Posts: 178 Comments: 56021
Quoting TampaTom:


Yeah... there's this thing called 'Neutral' you can shift to faster than you can call 9-1-1....

is it illegal to use a mobile phone while driving there, it is here. $250 fine and 3 demerit point.
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Quoting doabarrelroll:
Hurricane Question. Would a Hurricane "feel" worse in Penisular Florida than any other southern state because Florida is a Peninsula and the back side of a hurricane wont weaken as much as in other states?


Kinda a hard word (feel) to quantify, but I would say maybe :)

Here was the first identified Cat 5 storm (still trying to verify that per the embedded info) in the ATL. Note, the storm 2 years prior was eventually categorized as a Cat 5 also. I don't like Wiki, but here ya go... If memory servers, we have had a few of these strengthen over land in S. Fla.

1928 Okeechobee hurricane

Lot's of pics before and after.
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2010 year of surprizes thanks for quick update
Member Since: July 15, 2006 Posts: 178 Comments: 56021
278. JeffMasters (Admin)
An interesting hybrid low has formed off the coast of Brazil, near 30.5S 48W, over 26C water. The low is experiencing some westerly shear, but the convection has increased over the past hour. Here's a visible satellite image:



The latest WindSat pass shows the circulation nicely:



The ECMWF shows this low hanging out for 3 or so days. FSU phase space diagrams show warm core characteristics. Might be worth a dedicated post if this keep developing.

Jeff Masters
Member Since: July 15, 2006 Posts: 178 Comments: 56021
Quoting P451:
A little off topic, but...

What is so hard to understand here? What is wrong with these people? TURN THE CAR OFF.

-problem solved-

Link to image


What are these people doing? TURN THE DAMN KEY TO OFF.


lol?

It can't just be me....



Yeah... there's this thing called 'Neutral' you can shift to faster than you can call 9-1-1....
Member Since: June 20, 2005 Posts: 22 Comments: 1054
Quoting doabarrelroll:
Hurricane Question. Would a Hurricane "feel" worse in Penisular Florida than any other southern state because Florida is a Peninsula and the back side of a hurricane wont weaken as much as in other states?


I doubt it....Ask the folks on the "backside" of Katrina.......
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Quoting P451:
A little off topic, but...

What is so hard to understand here? What is wrong with these people? TURN THE CAR OFF.

-problem solved-

Link to image


What are these people doing? TURN THE DAMN KEY TO OFF.


lol?

It can't just be me....


Some people just hit the panic button in there brain and forget simple stuff like neutral and turning off the engine not removing the key then gently pull the hand brake on to slow the car down.
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Quoting P451:
A little off topic, but...

What is so hard to understand here? What is wrong with these people? TURN THE CAR OFF.

-problem solved-

Link to image


What are these people doing? TURN THE DAMN KEY TO OFF.


lol?

It can't just be me....



if you turn the key to off the steering wheel will lock. i was doing 80 down a frewway when young and as a joke a friend reached and pulled the key out of the ignition. the steering wheel locked and panic ensued while he tried to get the key back into the ignition while i was braking and running off the road in heavy traffic, headed for a huge concrete culvert.
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Quoting Jeff9641:


From what i see we will be under a slight risk area Firday for Central and North Florida as energy increases do to a strenghtening upper low on Friday. This will put us on the SE Quad which is prime for severe weather.


SPC may update tommorow for Florida as conditions warrant but the advancing cloud shield will hopefully have a dampening effect...I think its a wait and see right now.
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Quoting PensacolaDoug:



Steering column locks. Put it in "neutral" instead.


That would keep the power steering and power brakes working. I don't think many folks know what it is like to drive a car without those items functional, especially the stopping part :)
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Quoting Jeff9641:
Get ready for more Tornadoes Wednesday and then again on Friday in Central and North Florida. Both of these days appear to be dangerous. We could have numerous tornadoes some of them F3 or greater. 60 to 70 degree dewpoints will surge across all of the gulf coast states over the next few days. This moisture laden dewpoint air move from the Texas coast to Florida over the next 48 hours.


Good Morning........The risk will be there but not sure of the "certainty" yet as conditions unfold per the current SPC discussion below. I think that the worst of the normal Spring tornado threat for Florida and the SE will unfold over the next three weeks as temps in the Southeast start to really rise:

NWS STORM PREDICTION CENTER NORMAN OK
0229 AM CST TUE MAR 09 2010

SOUTHEAST STATES/GULF COAST TO FL PENINSULA...
SHOWERS/TSTMS WITH AT LEAST AN SOLATED/MARGINAL SEVERE POTENTIAL SHOULD BE ONGOING ACROSS THE GULF COAST VICINITY/ADJACENT SOUTHEAST STATES EARLY THURSDAY AHEAD OF AN EASTWARD ADVANCING COLD FRONT. POTENTIAL FOR ONGOING CLOUD COVER/PRECIPITATION CONSIDERABLY COMPLICATES THE FORECAST SCENARIO AT THIS TIME. HOWEVER...AT LEAST SOME SEVERE THREAT MAY CONTINUE OR PERHAPS INCREASE LATE ACROSS NORTH/CENTRAL FL GIVEN RENGTHENING/INCREASINGLY DIFFLUENT FLOW ALOFT BETWEEN POLAR/SUBTROPICAL JETS...COUPLED WITH AN INCREASING PREVALENCE OF 60S F SURFACE DEWPOINTS ACROSS THE FL PENINSULA. BUT GIVEN THE AFOREMENTIONED UNCERTAINTIES...A SLIGHT RISK IS NOT CURRENTLY WARRANTED.
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Quoting Jeff9641:
Get ready for more Tornadoes Wednesday and then again on Friday in Central and North Florida. Both of these days appear to be dangerous. We could have numerous tornadoes some of them F3 or greater. 60 to 70 degree dewpoints will surge across all of the gulf coast states over the next few days. This moisture laden dewpoint air move from the Texas coast to Florida over the next 48 hours.
dont know what ya see but my severe section on my blog is not forecasting anything to severe there will be some but not as bad as f3 tornadoes check it out if ya don't beleived me

link to personel wunder blog
Link
Member Since: July 15, 2006 Posts: 178 Comments: 56021
Good Morning!

I hope Neutral works better. The NPR report said he was trying to turn it off but had to slow down below 55 before that would unlock.
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Quoting P451:
A little off topic, but...

What is so hard to understand here? What is wrong with these people? TURN THE CAR OFF.

-problem solved-

Link to image


What are these people doing? TURN THE DAMN KEY TO OFF.


lol?

It can't just be me....




Steering column locks. Put it in "neutral" instead.
Member Since: Posts: Comments:
Quoting P451:
A little off topic, but...

What is so hard to understand here? What is wrong with these people? TURN THE CAR OFF.

-problem solved-

Link to image


What are these people doing? TURN THE DAMN KEY TO OFF.


lol?

It can't just be me....



LOL works well in any situation.
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NCDC
In Florida, February 2010 4th coldest in 116 years
Link

Winter 9th coldest
Link
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National Review NCDC
February 2010 was the 29 coldest in 116 years. Winter (December 2009-February 2010) was 18 coldest in 116 years.

The February 2010 temperature for the contiguous United States was 32.4 degrees F, which is 2.2 degrees below the long-term average.
Link
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Good Morning
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Morning all, Now this is much better. Weird storms in texas and kansas last night. Did anybody see the video on the wc of the nado in kansas and the temp was like 52.
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Brazil storm is now an official invest, SL90 (AKA 90Q)


SL 90 2010030800 BEST 0 252S 426W 30 1000 LO
SL 90 2010030806 BEST 0 260S 426W 30 1005 LO
SL 90 2010030812 BEST 0 273S 426W 30 1005 LO
SL 90 2010030818 BEST 0 293S 443W 30 1005 LO
SL 90 2010030900 BEST 0 300S 455W 30 1005 LO
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252. xcool




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251. xcool
hey all.
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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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