Record warmth in Atlantic Main Development Region for hurricanes

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

Share this Blog
3
+

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

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: 451 - 401

Page: 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15Blog Index

Quoting CycloneOz:
Of all the news crews present at Hurricane Ike, I was the only one to record destruction during the storm.

Somewhere near the middle of the video, you'll see part of the Mermaid Pier take the "deep six" into the Gulf.

It was an amazing time for me at that moment. I had the camera set up recording on its own. I was off talking to the mets, and we were wondering when the surge was going to hit. When I went back to my camera, I looked out and noticed that something "had changed" in the shot.

It wasn't until I got home and watched the footage that I saw I had captured a critical destructive moment of the storm.

An insurance adjustment agency out of Maryland bought 10 copies of the DVD last year just because I had captured that moment.


WOW! That must have been incredible!! Boy, what I would give to have been there too, haha!
Member Since: Posts: Comments:
Quoting jeffs713:

I would rather have spring last longer. How about 3 months, instead of 3 weeks?

Hah. Combine fall and spring for a total of ~4 weeks, which I usually call fring (as there is normally nothing at all in between...unlike this year).

3 months of spring sounds weird...to I-10 folks east of San Antonio, anyway.
Member Since: August 16, 2007 Posts: 6 Comments: 12463
Quoting StormChaser81:


Sometimes it seems Florida skips spring and goes right into summer, dont blink cause you'll miss spring, Remember spring is were all the nice cool looking birds leave the state and the insects start the return.

I curious to see how the insects reacted to the freezing temperatures over Florida, I have a feeling there will be less of them till they catch up later in the summer.

Historically here in SETX, the summer after a hard winter (by our standards) has less issues with insects all year. The populations never fully catch up, especially if people are vigilant in preventing them (this applies mostly to mosquitos).
Member Since: August 3, 2008 Posts: 16 Comments: 5891
Quoting jeffs713:

I would rather have spring last longer. How about 3 months, instead of 3 weeks?


Sometimes it seems Florida skips spring and goes right into summer, dont blink cause you'll miss spring, Remember spring is were all the nice cool looking birds leave the state and the insects start the return.

I curious to see how the insects reacted to the freezing temperatures over Florida, I have a feeling there will be less of them till they catch up later in the summer.
Member Since: August 11, 2008 Posts: 0 Comments: 2315
Quoting atmoaggie:

Okay. I'll take winter, gladly. Can we make it last a little longer?

My miserable meter is an exponential function of temps once they are above 80 F.

I would rather have spring last longer. How about 3 months, instead of 3 weeks?
Member Since: August 3, 2008 Posts: 16 Comments: 5891
here is probably the most uncomfortable heat I have had to deal with, went hiking in SW Illinois and the heat index was around 120 degrees.

this was due to the torrential rains following the remnants of hurricane dennis, and then a heat wave. there were heat indexes close to 130

Member Since: June 28, 2006 Posts: 25 Comments: 8360
Quoting jeffs713:

Trade ya.

From May 15 through September 15, our normal forecast is as follows:
High - 95F
Low - 75F
Humidity - too high. (80+%)
South or SE wind, 5-10mph
Partly Cloudy
20% chance of precip

EVERY
SINGLE
DAY

Okay. I'll take winter, gladly. Can we make it last a little longer?

My miserable meter is an exponential function of temps once they are above 80 F.
Member Since: August 16, 2007 Posts: 6 Comments: 12463
The image below is a NOAA-17 pass over the Kenai Peninsula 30 minutes ago. You can see the cloud streets coming out of the WSW right up Kachemak Bay, which are giving us one heck of a blizzard right now, for the 19th straight hour.




Current Conditions

Homer, Alaska (Airport)
Updated: 7 min 19 sec ago

9 F
Light Snow Freezing Fog
Windchill: -15 F
Humidity: 88%
Dew Point: 6 F
Wind: 34 mph from the SW

Wind Gust: 41 mph

Pressure: 29.00 in (Rising)
Visibility: 0.2 miles
Elevation: 82 ft
Member Since: November 24, 2005 Posts: 635 Comments: 26701
Quoting jeffs713:

Trade ya.

From May 15 through September 15, our normal forecast is as follows:
High - 95F
Low - 75F
Humidity - too high. (80+%)
South or SE wind, 5-10mph
Partly Cloudy
20% chance of precip

EVERY
SINGLE
DAY


ummmmm, well, I'll pass, I lived in Texas for 7 years, and I dont miss the summer
Member Since: June 28, 2006 Posts: 25 Comments: 8360
Quoting tornadodude:



yuck! lol I think our average high then is around 80

Trade ya.

From May 15 through September 15, our normal forecast is as follows:
High - 95F
Low - 75F
Humidity - too high. (80+%)
South or SE wind, 5-10mph
Partly Cloudy
20% chance of precip

EVERY
SINGLE
DAY
Member Since: August 3, 2008 Posts: 16 Comments: 5891
Quoting StormChaser81:


Just take the tank off before the storm hits and make sure the valve is shut off. Wind can cause the grill to fling the tank off and the tank becomes a leaking bomb and during a hurricane lots of sparks.

Oh, definitely. The grill (and tank) would both find a new home in the garage for a storm.
Member Since: August 3, 2008 Posts: 16 Comments: 5891
Quoting jeffs713:

Come June, 76 will be a normal LOW temp. blah.



yuck! lol I think our average high then is around 80
Member Since: June 28, 2006 Posts: 25 Comments: 8360
Quoting jeffs713:

Remember, grills can cook just about ANYTHING. Frozen pizza, coffee, frozen veggies, you name it, they can do it.


Just take the tank off before the storm hits and make sure the valve is shut off. Wind can cause the grill to fling the tank off and the tank becomes a leaking bomb and during a hurricane lots of sparks.
Member Since: August 11, 2008 Posts: 0 Comments: 2315
Quoting tornadodude:


yeah, I'll take that 76 come June, alright?

Doesnt usually get too unbearably hot here, although it isnt uncommon to hit 100 once a year

Come June, 76 will be a normal LOW temp. blah.
Member Since: August 3, 2008 Posts: 16 Comments: 5891
Quoting CycloneOz:


Houston? If that city is in the track of a tropical system, I'll probably be on either side of you - Galveston Island or Beaumont...

But yeah, I could do Houston! :)

Galveston = basically an extention of Houston. If the eye hits Galveston, or just west of it, Houston is in for a world of hurt. (see "Hurricane Ike").
Member Since: August 3, 2008 Posts: 16 Comments: 5891
Member Since: June 28, 2006 Posts: 25 Comments: 8360
FYI -

Here's what - and when - I'll be teaching and moderating during the National Hurricane Conference:

Workshop
I4 PUBLIC EDUCATION/MEDIA
Bridging the Gap: How Do We More Effectively Communicate?

Thursday, April 1, 2010
Time: 3:30 pm to 5:00 pm

Location: Lake Eola A/B, Lobby Level

Study after study indicates that a well‐educated public is better prepared to weather the effects of a hurricane. But, with the many responsibilities and distractions that come with everyday life, how can you get your audience to pay attention to this potentially life‐saving information? Take a creative ‐ and somewhat offbeat ‐ new tack to your hurricane preparedness messaging and make your public education blow your audience away. By using all of the tools available, your targeted message will attract more attention and have more media appeal. This workshop will also identify strategies and tools to promote a stronger and more accurate interpretation of hurricane forecast information and graphics by the residents of hurricane‐prone regions.

Moderator:
Tom Iovino, Communications Specialist, Pinellas County Communications Department, Clearwater, FL

Power to the Pipsqueaks: Teaching Preparedness to Children
Tom Iovino, Communications Specialist, Pinellas County Communications Department, Clearwater, FL

If You Like Twitter or Facebook, You’ll Really Like This – A Map‐Based Social Networking Platform Designed Especially for Emergency Response
Matt Diez, Geospatial Solutions Architect, IEM, Baton Rouge, LA

Helping the Public Understand Meteorological Products and Warnings
Lori Drake, Hurrnet, Dublin, CA

Public Outreach to the Evacuating Resident Begins Before the Storm: Florida’s 511
Mike Wacht, Assistant Project Manager, Outreach, 511 Project, Global 5 Communications, Longwood, FL
Member Since: Posts: Comments:
Quoting StormChaser81:


Yup i got my gas grill ready this time, It's going to be one big BBQ camping Bash.

Remember, grills can cook just about ANYTHING. Frozen pizza, coffee, frozen veggies, you name it, they can do it.
Member Since: August 3, 2008 Posts: 16 Comments: 5891
Quoting jeffs713:

Yeah, for y'all it would be a tad bit toasty. Down here, its a nice break from the "cold" weather we've had this winter. (cold in SE texas = downright balmy up in Indiana)

One good thing for the cold winter here is that many of the little critters that plague us during the summer died in the freezes. Then again... if past years are an indication, we may get a storm here in SETX this hurricane season, too.

Oh... and Oz, you are a wonderfully nice guy and all, but please stay away from Houston. If you're here after about May 1, you are bringing a guest we don't want.


yeah, I'll take that 76 come June, alright?

Doesnt usually get too unbearably hot here, although it isnt uncommon to hit 100 once a year
Member Since: June 28, 2006 Posts: 25 Comments: 8360
Quoting jeffs713:

Heh. I have a gas grill this time, and hopefully will be better prepared. That said... I don't want an uninvited guest this year.


Yup i got my gas grill ready this time, It's going to be one big BBQ camping Bash.

I'm going to get more supplies very soon before the opening ceremony.
Member Since: August 11, 2008 Posts: 0 Comments: 2315
Quoting StormChaser81:


We cant do that again, I don't have my camping supplies ready yet.

Basically after the hurricane passes, its just one big camp ground with no power and no safe running water and lots of noisy generators.

Heh. I have a gas grill this time, and hopefully will be better prepared. That said... I don't want an uninvited guest this year.
Member Since: August 3, 2008 Posts: 16 Comments: 5891
90Q 18Z

SL 90 2010030918 BEST 0 301S 484W 30 1000 LO


SAB

09/1745 UTC 30.0S 48.3W ST1.5 INVEST -- South Atlantic
Member Since: Posts: Comments:
Quoting CycloneOz:


Wow...what a coincidence.

Let's just do 2004 all over again.

THE 'I' STORM LOOMS!


We cant do that again, I don't have my camping supplies ready yet.

Basically after the hurricane passes, its just one big camp ground with no power and no safe running water and lots of noisy generators.
Member Since: August 11, 2008 Posts: 0 Comments: 2315
Quoting tornadodude:


touche

although 76 would probably seem a little too warm right now

Yeah, for y'all it would be a tad bit toasty. Down here, its a nice break from the "cold" weather we've had this winter. (cold in SE texas = downright balmy up in Indiana)

One good thing for the cold winter here is that many of the little critters that plague us during the summer died in the freezes. Then again... if past years are an indication, we may get a storm here in SETX this hurricane season, too.

Oh... and Oz, you are a wonderfully nice guy and all, but please stay away from Houston. If you're here after about May 1, you are bringing a guest we don't want.
Member Since: August 3, 2008 Posts: 16 Comments: 5891
Oz you have WU mail.
Member Since: August 11, 2008 Posts: 0 Comments: 2315
Member Since: June 28, 2006 Posts: 25 Comments: 8360
nice even up here in toronto
Member Since: Posts: Comments:
Quoting jeffs713:

I will take your nice weather and raise you one, kind sir.

South Tomball (Willow Falls), Tomball, Texas (PWS)
Updated: 4 sec ago
76.0 °F
Scattered Clouds
Humidity: 67%
Dew Point: 64 °F
Wind: 4.0 mphfrom the West
Wind Gust: 13.0 mph
Pressure: 29.73 in (Falling)
Heat Index: 78 °F
Visibility: 10.0 miles
UV: 7 out of 16
Clouds: Scattered Clouds 2700 ft
Scattered Clouds 4000 ft
(Above Ground Level)
Elevation: 154 ft



touche

although 76 would probably seem a little too warm right now
Member Since: June 28, 2006 Posts: 25 Comments: 8360
Quoting tornadodude:
so nice (:

Lafayette, Purdue University Airport
Lat: 40.43 Lon: -86.93 Elev: 623
Last Update on Mar 9, 1:54 pm EST

Fair

61 °F
(16 °C)
Humidity: 54 %
Wind Speed: S 8 MPH
Barometer: 29.82" (1009.9 mb)
Dewpoint: 44 °F (7 °C)
Visibility: 10.00 mi.

I will take your nice weather and raise you one, kind sir.

South Tomball (Willow Falls), Tomball, Texas (PWS)
Updated: 4 sec ago
76.0 °F
Scattered Clouds
Humidity: 67%
Dew Point: 64 °F
Wind: 4.0 mphfrom the West
Wind Gust: 13.0 mph
Pressure: 29.73 in (Falling)
Heat Index: 78 °F
Visibility: 10.0 miles
UV: 7 out of 16
Clouds: Scattered Clouds 2700 ft
Scattered Clouds 4000 ft
(Above Ground Level)
Elevation: 154 ft

Member Since: August 3, 2008 Posts: 16 Comments: 5891
Quoting CycloneOz:
If that Brazilian 90L freak becomes a TS, what will it be named?


we could call it

freak 1 south atlantic basin
Member Since: Posts: Comments:
so nice (:

Lafayette, Purdue University Airport
Lat: 40.43 Lon: -86.93 Elev: 623
Last Update on Mar 9, 1:54 pm EST

Fair

61 °F
(16 °C)
Humidity: 54 %
Wind Speed: S 8 MPH
Barometer: 29.82" (1009.9 mb)
Dewpoint: 44 °F (7 °C)
Visibility: 10.00 mi.
Member Since: June 28, 2006 Posts: 25 Comments: 8360
Quoting CycloneOz:
If that Brazilian 90L freak becomes a TS, what will it be named?


Catarina again?

it has been 6 years lol
Member Since: June 28, 2006 Posts: 25 Comments: 8360
Quoting WaterWitch11:


thanks

Sry, I was teasing a little. Happened in 2004. Other than that, I don't think we know about any others.
Member Since: August 16, 2007 Posts: 6 Comments: 12463
Quoting atmoaggie:

Every 6 years in the 21st century...so far, anyway.


thanks
Member Since: Posts: Comments:
Quoting twhcracker:
my momma always said it wasnt spring til the scuppernongs budded out and i have observed that to be a hard fact.

Okay...
http://en.wikipedia.org/wiki/Scuppernong

Now that I have learned my new word of the day...L8R.
Member Since: August 16, 2007 Posts: 6 Comments: 12463
my momma always said it wasnt spring til the scuppernongs budded out and i have observed that to be a hard fact.
Member Since: Posts: Comments:
Quoting WaterWitch11:
does anyone know how often 90L scenario occurs?

Every 6 years in the 21st century...so far, anyway.
Member Since: August 16, 2007 Posts: 6 Comments: 12463
does anyone know how often 90L scenario occurs?
Member Since: Posts: Comments:
Quoting tornadodude:


well I mean, its an area of low pressure that doesnt seem to be moving too fast, and is drwing some warm moist air up from the gulf


thats spring?? its been doing that all winter.
Member Since: Posts: Comments:
Quoting Jeff9641:


Yeah I know but some people on here seem to think I'm nuts. If I was a storm chaser I would be in the Arklatex area because I feel numerous tornadoes will occur tomorrow thru tomorrow night. Also, second resurgence will occur late Thursday into Friday in Florida.
or ?

Personally, I think the CAPE will be there. Not sold on the shear.
Member Since: August 16, 2007 Posts: 6 Comments: 12463
Quoting JeffMasters:
Brazilian disturbance is up as 90L on the NRL web site:



Could be a subtropical depression or storm if it develops some more convection and hangs together another 6 - 12 hours.

Jeff Masters

thanks doc will be back at 4-5 ish to talk more
Member Since: Posts: Comments:
BBL
Member Since: November 24, 2005 Posts: 635 Comments: 26701

Viewing: 451 - 401

Page: 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15Blog 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
35 °F
Overcast

JeffMasters's Recent Photos

Lake Effort Snow Shower Over Windsor, Ontario
Sunset on Dunham Lake
Pictured Rocks Sunset
Sunset on Lake Huron