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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We've had anomalous upper easterlies so far this year, for the last several months in a row. Wind shear has been below normal all year long so far.

And wow look at the the last 30 days showing a jet of upper easterlies colliding with a jet of westerlies in the central Pacific. That's the sink hole of death for the tropical season out there! When upper air converges that strongly, it races downward, and sinking air like that puts a strong cap on convection.



Wind shear = still below normal:

Member Since: Posts: Comments:
Quoting zoomiami:
Seems like some of the gentlemen on here don't know which brain to use to remember Tropical Amanda, hmm


We have warned you before about using logic and facts... thats what gives you the headaches.. now stop it :)
Member Since: October 1, 2007 Posts: 81 Comments: 26511
Quoting zoomiami:
Seems like some of the gentlemen on here don't know which brain to use to remember Tropical Amanda, hmm
be good zoo shhh i like watchin them make fools of themselves and its kinda funny too
Member Since: July 15, 2006 Posts: 174 Comments: 54639
Quoting hunkerdown:
will it lift out or get left behind...


Lifted out. Starting tomorrow.
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Quoting KEEPEROFTHEGATE:
the process has begun there is nothing more but a matter of time once the lower life forms are gone so are we


GASP!!! where is JFV going?
Member Since: October 1, 2007 Posts: 81 Comments: 26511
Quoting zoomiami:
Seems like some of the gentlemen on here don't know which brain to use to remember Tropical Amanda, hmm
it may suit him better...
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Quoting zoomiami:
Seems like some of the gentlemen on here don't know which brain to use to remember Tropical Amanda, hmm
Like Pat says...U Betcha...
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Want to see something scary? Go to this loop and click on the SST box in the top right corner. Not pretty.

Link
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Quoting MiamiHurricanes09:
It's under 20 knots of southerly shear.

will it lift out or get left behind...
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Seems like some of the gentlemen on here don't know which brain to use to remember Tropical Amanda, hmm
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The reading of 1009mb in the northern quadrant is obviously suspect considering every other observation in and around the system consists of pressures above 1014mb with several reaching 1016mb.

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Quoting JFLORIDA:
The phytoplankton info is very new and very alarming. With good reason, it is important in regulation atmospheric gases as well as a major component of the ocean food chain.

I would wait and see the arguments before jumping to conclusions.
the process has begun there is nothing more but a matter of time once the lower life forms are gone so are we
Member Since: July 15, 2006 Posts: 174 Comments: 54639
Quoting Bipartisanship:
suite yourself, 77. im a real keeper, haya tu, mandanga y zangana, anyhow, levi? ^_^ maniatica
thats why you are fishing on a blog for a date/mate...
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While we're on the subject of GW...
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Quoting jasoniscoolman2010x:
wow look at this t.storms on the east coast
It's under 20 knots of southerly shear.

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good friday evening storm,whats cooking [or not cooking] this evening?
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265. unf97
Good evening everyone!
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With warm SSTs and all the extra nutrients added, I would think that there would be more microscopic marine phytoplankton.
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Quoting Levi32:


Lol.....

What? Says I.



By the way.....the ENSO is not the end all be all for tropical activity in the Atlantic.....2005 ring any bells? Neutral year...



Yeah, um, those anomalies in the Atlantic are not falling. In fact, the Caribbean looks like it's getting worse.
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guys 90L will develop and the wave behind it will aid to that also I see a track taking 90L into the Caribbean I have more to say after I eat I am very very hungary
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260. 7544
Quoting jasoniscoolman2010x:
i see that coming soon


yeap is it still moving sw or better yet where will it head
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By the way.....the ENSO is not the end all be all for tropical activity in the Atlantic.....2005 ring any bells?

several...
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Quoting earthlydragonfly:


I think the tongue has to be in mouth in order to argue...

Where was she on the GW blog... She would have helped... Obviously she is a product of GW.


Oh my when I saw GW blog I ran out the door and went fishing... I wasnt going there nor will I...lol
Member Since: July 3, 2010 Posts: 0 Comments: 427
Quoting Orcasystems:


Its not a surprise... Levi has been talking about it for days, so I have been putting it as an AOI ever since. When Levi talks... smart people listen. BTW, its a "thingie" not a surprise.


You said you were putting your thingie away!
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Quoting earthlydragonfly:



Ill stop... Sorry everyone... Gotta have some fun...
You know I was just messin' witcha! LOL!
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Quoting CybrTeddy:


Afternoon Levi. No sense reason with those who cannot be reasoned with.


Hey Teddy. I suppose not.
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Quoting stormpetrol:
Well Like I said before, with all that convection
from basically the Gulf of Honduras to the West African Coast if something doesn't develop, then I'll start to doubt this season with its predictions in terms of numbers. i'm still going with 19/10/6 though.
yeah it seems like every strong tropical wave that has came off of africa has poofed out or not developed.seems like we are in a pattern, with something stopping their development,I am beginning to doubt all the hyped up predictions to...
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Quoting MiamiHurricanes09:
Oooookkkk....LOL!



Ill stop... Sorry everyone... Gotta have some fun...
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Good evening, everyone!

MAN, it is so freaking HOT here. It's 97F with a heat index of 107F. Tomorrow, the high is supposed to be 102F and Sunday it's supposed to be 103F with heat indexes over 110F. Needless to say, we are in the dog days of summer. I'm sure the water temps around the SE coastline will respond accordingly.

Anyway, looks like it's status quo with 90L. I'm with Doc in that it will probably merge with the system coming off Africa. I could see 90L using the moisture and energy from the tropical wave and the tropical wave using the circulation from 90L. If they can get it together later this weekend, I see no reason why this area wouldn't become a hurricane down the road.
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Quoting Levi32:


Lol.....

What? Says I.

By the way.....the ENSO is not the end all be all for tropical activity in the Atlantic.....2005 ring any bells? Neutral year...



Afternoon Levi. No sense reason with those who cannot be reasoned with.
Member Since: July 8, 2005 Posts: 259 Comments: 24265
Quoting tkeith:
BP didn't help none either...


Yeah, and they're not alone...
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Quoting StormW:


Doing well, doing well! Don't you mean more like keeping them in line?


HA GOOD LUCK WITH THAT...
Member Since: July 3, 2010 Posts: 0 Comments: 427
Quoting Jeff9641:
We may have a surprise storm brewing off the SE US.


Its not a surprise... Levi has been talking about it for days, so I have been putting it as an AOI ever since. When Levi talks... smart people listen. BTW, its a "thingie" not a surprise.
Member Since: October 1, 2007 Posts: 81 Comments: 26511
Quoting hurrkat05:
well stormpetrol you are right to doubt the 18 storms no way that happens they are lucky if 3 storms form in august...im still saying 13 however im beginning to worry about that...dr gray will have lots to say and i bet you we are in the neutral year we are sure not in a lanina...we will find out soon enough..


Lol.....

What? Says I.



By the way.....the ENSO is not the end all be all for tropical activity in the Atlantic.....2005 ring any bells? Neutral year...

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Quoting ho77yw00d:


I'm ok just trying to keep up with these guys in here lol... and you sir?


Oh no..... She said sir.... Sorry Sir...
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Quoting earthlydragonfly:


I think the tongue has to be in mouth in order to argue...

Where was she on the GW blog... She would have helped... Obviously she is a product of GW.
Oooookkkk....LOL!
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in other news ice is still melting

Member Since: July 15, 2006 Posts: 174 Comments: 54639

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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.