Little change to 90L; new African tropical wave is worth watching

By: Dr. Jeff Masters , 8:53 PM GMT on July 30, 2010

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Invest 90L is a tropical wave in the eastern Atlantic near 10N 33W with a very limited amount of heavy thunderstorm activity but a decent amount of spin. It does not have a well-defined surface circulation, and has shown little change in organization today. CIMMS wind-shear analyses show a low amount of wind shear (5 - 10 knots) over 90L, and sea surface temperatures are a record warm 29°C. The wave currently is in a moist environment and is not being affected by the dry Saharan Air Layer (SAL) to its northwest. The disturbance has moved far enough away from the Equator to leverage the Earth's spin to help it develop. The Saharan Air Layer with its dust and dry air lurks just to the north of 90L, but the SHIPS model predicts 90L will remain far enough from the dry air over the next five days so that it will not interfere with development.


Figure 1. Afternoon visible satellite image from 2pm EDT 7/30/10 of the relatively tiny 90L, and the large new tropical wave that moved off the coast of Africa yesterday.

Forecast for 90L
One factor inhibiting development of 90L this week will be the Madden-Julian Oscillation (MJO.) The MJO currently favors downward motion over the tropical Atlantic, which will act to decrease the chances of tropical storm formation. The Madden-Julian oscillation is a pattern of enhanced rainfall that travels along the Equator from west to east. The pattern has a wet phase with large-scale rising air and enhanced thunderstorm activity, followed by a dry phase with large-scale sinking air and suppressed thunderstorm activity. Each cycle lasts approximately 30 - 60 days. When the Madden-Julian oscillation is in its wet phase over a hurricane-prone region, the chances for tropical storm activity are greatly increased.

Perhaps the main factor interfering with 90L's development will be the presence of the large tropical wave to the east of 90L that moved off the coast of Africa yesterday. This new wave is large enough and close enough to 90L that it will probably begin to dominate regional weather patterns this weekend, stealing away 90L's inflow of low-level moist air. The new wave may also act to bring sinking air over 90L that will tend to suppress 90L's thunderstorm activity. It may turn out that the new wave will also steal some of 90L's spin, and end up being a threat to develop itself later on this weekend.

The latest 8am EDT (12Z) model runs for 90L show very little in the way of development of the storm. The predominant track forecast takes 90L into or just north of the northern Lesser Antilles Islands about 6 - 8 days from now. Looking at climatology based on research done by Dr. Bob Hart at Florida State University,, 90L has a 19% chance of developing into a tropical cyclone by 2pm Sunday. NHC is putting these odds at 20%. Dr. Hart also has an experimental product showing that historically, about 30% of all tropical cyclones that develop at 90L's current position eventually hit land as a hurricane. Of course, 90L is not yet a tropical cyclone, and I think that the large tropical wave off the coast of Africa will kill 90L this weekend.

Tropical wave in the eastern Caribbean
A tropical wave in the eastern Caribbean, south of the Dominican Republic, is moving west at 15 - 20 mph with no signs of development. The wave is under a high 20 knots of wind shear, due to strong upper-level westerly winds from an upper level low centered north of Puerto Rico. This shear is expected to remain remain high through Saturday. By Sunday, when the wave will be approaching Nicaragua, the wave will be far enough away from the upper level low that shear should fall to the moderate range, 10 - 20 knots. Some development is possible on Sunday, but the wave will have only about a 1-day window to develop before its westerly motion brings it inland over Nicaragua on Monday. NHC is giving this wave a 10% chance of developing into a tropical depression by 2pm Sunday.

Extreme cold records for 2010
In my post yesterday, I reported that fourteen countries had set their all-time hottest temperature record this year. I neglected to mention that one country has also set its coldest temperature in recorded history mark in 2010. Guinea had its coldest temperature in its history on January 9, 2010, when the mercury hit 1.4°C (34.5°F) at Mali-ville in the Labe region. Of the 229 countries with extreme coldest temperature records, 14 of these records have occurred in the past ten years (6% of all countries). There have been five times as many (74) extreme hottest temperature records in the past ten years (33% of all countries.) My source for extreme weather records is Chris Burt, author of Extreme Weather.

New study finds huge drop in the plants that form the base of the oceanic food chain
A study published this week in the journal Nature documents that microscopic marine phytoplankton, which form the basis of the marine food chain, have declined by 40% globally since 1950. Joe Romm at climateprogress.org discusses the implications, using this headline:

Scientists may have found the most devastating impact yet of human-caused global warming — a 40% decline in phytoplankton since 1950 linked to the rise in ocean sea surface temperatures. If confirmed, it may represent the single most important finding of the year in climate science.

I plan to discuss this paper next week.

Next update
I'll have an update this weekend, probably by 8pm EDT Saturday.

Jeff Masters

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Quoting Orcasystems:


I wouldn't even have known about the statement if you had not quoted it.

Don't feed a troll...and it will go back to where it came from :)



I sure wish that were true...
Member Since: July 1, 2005 Posts: 10 Comments: 1683
Quoting Tazmanian:



he had posted 3 times and its geting annyoing when some one keeps posting the same thing

Taz... Ignore. You are the man and we know it..
Member Since: Posts: Comments:
Hey I'm big on GM/CC because of the science but think best to not do it too much on this blog during the season. I've posted some but no intent to "Stir it up". No one is going to change their mind based on post on this blog expect maybe JM’s detailed Blog entries on aspects of this subject which he likes to do when tropics are slow. I think he knows many don't follow the science and thinks it's a public service to educate the public. Peace..
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Quoting Bordonaro:

Thanks, feeling alot better!!


Glad to hear it. I am from Corpus Christi originally. Experienced 10 Storms in my 47 years life on the Texas coast-Beulah, Celia,Fern, Delia, Amelia, Allen, Brett, Allison, Rita and Ike.

Celia and Ike were the worst. They were the reasons I pursued my degree in meteorology years ago.
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Quoting earthlydragonfly:


I dont see anyone attacking in this statement... It even says please... attack? really??


I wouldn't even have known about the statement if you had not quoted it.

Don't feed a troll...and it will go back to where it came from :)
Member Since: October 1, 2007 Posts: 81 Comments: 26511
I dont put people on ignore. Maybe its time I start.
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Quoting StSimonsIslandGAGuy:
OK are there any models or forecast tracks out about the Bahama/Bermuda blob?


No because it's not an invest. It should get lifted north starting tomorrow with baroclinic influence and I don't really consider it a threat for tropical development. However, you can see what the tail-ends of these fronts want to do over the exceptionally warm water.
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Quoting StSimonsIslandGAGuy:
The blob between the Bahamas and Bermuda will take a long time to transition, if it ever does. At least 48 hours.

They always seem to look impressive and they are close enough that I feel I have to watch em, but they don't produce much quickly.

Perhaps it is a storm with a great future and always will be.

Hopefully this Bahama Blob slowly goes pfft, or we may have problems along the E Coast!
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Quoting StSimonsIslandGAGuy:
Jan-March were cold in FL/GA, but Florida has seen plenty colder. The SC/GA piedmont saw heavier snows in 1973. Over 20 winters in Baltimore, DC and Philly have been colder. And in many places, winter temps were above normal.

So what?

The coldest it got on St. Simons this past winter was 23. The all-time record low is 6

A winter that only gets within 17 degrees of the all-time record low is not that extraordinary.



You're saying just because one city didn't break a record means the winter wasn't that bad? Maybe not for you but there were historic snow totals in the eastern US and in the southern US in places like Texas. At one point, the snow map showed nearly uniform snowcover across the entire US east of the great plains all the way down to the north gulf coast. That almost never happens. You mentioned the extreme cold in Florida as well. Ask the people living down there. This was a historic winter and one we will not see again for a long time.
Member Since: Posts: Comments:
I never said you were violating a ban. And 1 time in my mailbox was one too many.
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Quoting JFLORIDA:


First off I wrote you one email three days ago asking you to cut the garbage and not say I was violating a ban.

I dont appreciate your continuous attacks.


I dont see anyone attacking in this statement... It even says please... attack? really??
Member Since: July 1, 2005 Posts: 10 Comments: 1683
Quoting NoNamePub:


Taz First time I had seen it.


Scroll down its about every 10th post
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Quoting StSimonsIslandGAGuy:
OK are there any models or forecast tracks out about the Bahama/Bermuda blob?


i think steering shows it pulling off to the NE
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Wow, they appear bullish on the African Wave JasonisCoolman, right? Dr. Masters appears to think it may swallow 90L by the weekend.
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Quoting NoNamePub:


Taz First time I had seen it.



he had posted 3 times and its geting annyoing when some one keeps posting the same thing
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Quoting Dennis8:


I hope you are feeling better my fellow Texan. i read you were under the weather. Stay cool. My mom hails from Dallas..many moons ago. Family used to ALMOST own Mabank, Texas

Thanks, feeling alot better!!
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Re: 442

Thats not my qoute JFlorida. Thats yours. But the way you re-posted it makes it look like it's mine. Take it down please
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Quoting StSimonsIslandGAGuy:
Jan-March were cold in FL/GA, but Florida has seen plenty colder. The SC/GA piedmont saw heavier snows in 1973. Over 20 winters in Baltimore, DC and Philly have been colder. And in many places, winter temps were above normal.

So what?

The coldest it got on St. Simons this past winter was 23. The all-time record low is 6

A winter that only gets within 17 degrees of the all-time record low is not that extraordinary.



Apparently here in Macon, GA we got to a low of -6 in an arctic outbreak in January of 1985. I was really shocked to see that. It was 10 years before I was born though, so this is the most extraordinary winter at least I've seen.
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Quoting Tazmanian:



we dont need too keep see that map


Taz First time I had seen it.
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Quoting Bordonaro:

Dallas Ft Worth, TX would like to borrow 5", so we can be at normal for the year.

June 2010 averaged 86.3F, about 6F above normal.

July 2010 averaged about 86F, which is about 1F above normal. Only 6 days above 100F total, so far, we should tack on 8 in the next 10 days.

Gotta love TX weather!!


I hope you are feeling better my fellow Texan. i read you were under the weather. Stay cool. My mom hails from Dallas..many moons ago. Family used to ALMOST own Mabank, Texas
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Quoting Levi32:


Yes unlikely lol. We just went through one of the most historic winters we will all ever see for the eastern and southern United States.


I'm still hoping for the off-chance! Have no problem being the underdog lol.
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Quoting CybrTeddy:
I don't think 90L itself will develop, rather serve as that catalyst for the wave behind it to start developing.

I think you're right on the button, it will interact and steal 90L center along with its massive convection and become as one, wow sounds like I just pronounced them man and wife :)
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Quoting jasoniscoolman2010x:
this green color on here not good at all.



we dont need too keep see that map
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Quoting tramp96:
I think the Bush admn. thought g.w. was true.

We didn't sign on to the Kyoto Treaty under Bush. And we still haven't signed on under Obama.
In his defense, he's saying he wants national legislation first. It's still held up in the senate. Lots of oil money floating around.
Then it sinks under the surface and you can't see it...
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Quoting Dennis8:
Evening. Ladies & Gentlemen. 18.09" Rain this July at my home ~3 miles north Downtown Houston. Today NO Rain (18/30 days w/ rain ) and a high of 96 degrees. 29.91" at 7:20 pm. Lots fluffy Cu in the sky today. I hope everyone has a great evening and lots of respectful, lively discussion.

Dallas Ft Worth, TX would like to borrow 5", so we can be at normal for the year.

June 2010 averaged 86.5F, about 6F above normal.

July 2010 averaged about 85.7, which is about 0.8F above normal. Only 6 days above 100F total, so far, we should tack on 8 in the next 10 days.

Gotta love TX weather!!
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Cyber i think it is the tail end of a cold front that came through my area last night. We had a lot of thunder and lightening with it
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Quoting Chicklit:


Funny, I'm not taking your word for it.


Good, you shouldn't. Never take anyone's word for it. One should always draw their own conclusions and look up stuff for themselves to see what's going on.
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Quoting earthlydragonfly:


HMMMMMM or with Clinton... this information was available to him as well... You neglected to mention him... HMMMmm.. Wake up folks.. it is ALL OF THEM! Like it or not!! They are all on the take in DC period.. They love to divide and conquer.... So many brainy people in here but still think it is one party against another... So silly....

It is us against them period. United we stand!


I avoid politics overall and here b/c this is weather....that being stated....


***WELL SAID***


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Re: 442

Thats not my qoute JF. Thats yours. But the way you re-posted it makes it look like it's mine. Take it down please.
Member Since: Posts: Comments:
Evening. Ladies & Gentlemen. 18.09" Rain this July at my home ~3 miles north Downtown Houston. Today NO Rain (18/30 days w/ rain ) and a high of 96 degrees. 29.91" at 7:20 pm. Lots fluffy Cu in the sky today. I hope everyone has a great evening and lots of respectful, lively discussion.
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Quoting TropicalAnalystwx13:


This year and next year will be La Nina years, so yeah, thats pretty much not happening, although there is always a possibility..


Yeah... I hope next year goes Nino sometime before winter arrives though. Call me a snow-caster! And 2008 was a La Nina year, and we had snow the 2008-2009 summer as well. Although it was on March 1st 09 and La Nina was likely well over by then lol.
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Quoting Levi32:


Yes unlikely lol. We just went through one of the most historic winters we will all ever see.


Funny, I'm not taking your word for it.
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Quoting StSimonsIslandGAGuy:


Record lows?


She means record high lows lol.
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Quoting Chicklit:


We've had more record low temperatures in Florida here this year than I can ever remember.
It's almost a daily thing now.

I figured your were all frying on FL, after the brutal winter you've had!
Member Since: Posts: Comments:
Just had a rip-roaring storm blow through here on the edge of the Everglades.....thunder, lots of lightning, and WIIIIIIINNNNNNNNNNNDDDDDDDD! It seems to have passed now, but was it ever powerful!
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Quoting HurricaneSwirl:
So, Levi, I guess this type of situation would be extremely unlikely this winter?



Was unlike anything I've ever seen. Would love to experience it again. However I would not want to see all of those crops destroyed again.


Yes unlikely lol. We just went through one of the most historic winters we will all ever see for the eastern and southern United States.
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Quoting jasoniscoolman2010x:



p;z stop flooding up the blog with that thank you
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Quoting will45:


looks like it is still attached to that trof


Your right too, and surface pressures are high there too. Its a interesting feature none of the less.
Member Since: July 8, 2005 Posts: 259 Comments: 24164

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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.