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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in other news ice is still melting

Member Since: July 15, 2006 Posts: 174 Comments: 54372
Quoting MrMarcus:
"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."

After reading the article, I find it surprising that none of the scientists have even considered the possibility that, with as much pollution as we've dumped in the waterways over the last 100 or so years, that water pollution, and not global warming, might be the cause...
BP didn't help none either...
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Quoting KEEPEROFTHEGATE:
you notice that too huh lol


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.
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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! You criticize us for not knowing anything and you don't even know how to read a SSTs anomaly graph.
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hi guys whats new with 90L and others i have not had a chance to check today , just read doc blog
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"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."

After reading the article, I find it surprising that none of the scientists have even considered the possibility that, with as much pollution as we've dumped in the waterways over the last 100 or so years, that water pollution, and not global warming, might be the cause, especially in light of the following quote from the article:

"But ocean warming does not explain reduced productivity in regions, including the Arctic Ocean, where algal growth is mainly constrained by sunlight."
Member Since: January 2, 2008 Posts: 0 Comments: 97
Quoting breald:


Thank you!! I mean all he needs to do to see an attractive woman is drive to the freakin beach. He lives in South Florida for christ sake.


You boys are just silly to me.
ROFL!
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Quoting StormW:


Hi back!
How are you this evening?


I'm ok just trying to keep up with these guys in here lol... and you sir?
Member Since: July 3, 2010 Posts: 0 Comments: 427
Quoting ho77yw00d:


hm idk earlier we had a weird conversation about ducks...lol


lol
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Quoting MiamiHurricanes09:
Ok while JFV heads to eHarmony can we please get back on topic.


Thank you!! I mean all he needs to do to see an attractive woman is drive to the freakin beach. He lives in South Florida for christ sake.

You boys are just silly to me.
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226. xcool
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Quoting StormW:
Good evening!


Evening Storm!
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Quoting earthlydragonfly:


I tell you what I like.... Everyone's bickering seems to go away when your around!!

THANK YOU!
you notice that too huh lol
Member Since: July 15, 2006 Posts: 174 Comments: 54372
Quoting earthlydragonfly:


I tell you what I like.... Everyone's bickering seems to go away when your around!!

THANK YOU!


hm idk earlier we had a weird conversation about ducks...lol
Member Since: July 3, 2010 Posts: 0 Comments: 427
Quoting msgambler:
evening earthly


Evening right back at you also :)
even if it is only the afternoon.
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This is one heck of a pattern in the Atlantic with the GFS still showing the Azores High way up at 50N (climatological position is 35N) and well below-normal pressures in the tropical Atlantic. This is not the best setup for Cape Verde development as you get a lot of dry air invading from the northeast, propelled into the tropics by the flow on the southern flank of the Azores High.

But, it is a bad pattern for the Caribbean and United States because in such a setup the tropical Atlantic becomes the incubator which keeps tropical waves alive and growing but tame.....however the SW Atlantic basin then becomes the nest where the eggs start to hatch and these waves start to pop open farther west and in areas where they can threaten land almost anywhere they go. That is where all the moisture and greatest heat buildup has been so far this year. Look at where we had Alex, TD #2, and Bonnie, right in the nest.

GFS Day 10 shows the Azores High well to the north and the axis of tropical precipitation aimed out of the central Atlantic into the United States and Caribbean.

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216. xcool
hmmm
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hi Storm ;)
Member Since: July 3, 2010 Posts: 0 Comments: 427
Quoting ho77yw00d:



lmao ...too funny


I tell you what I like.... Everyone's bickering seems to go away when your around!!

THANK YOU!
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700mb vorticity associated with PGI21L isn't that bad.

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evening earthly
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Quoting msgambler:
And she fought him....LOL

Evening Orca



LOL Evening gambler
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Quoting earthlydragonfly:


I wouldnt if I were you... Remember (Closed)!!! LOL



lmao ...too funny
Member Since: July 3, 2010 Posts: 0 Comments: 427
Quoting StormW:
Good evening!


Thank god your here... say something smart and save us.. we are on the slippery slope.
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Quoting StormW:
Good evening!
Good evening Storm!
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Quoting earthlydragonfly:


only girl to get out of the wrapper was Little Debbie...
And she fought him....LOL

Evening Orca
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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.
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Quoting sammywammybamy:




If only DestinJeff were here...
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Ok, lets get back on track... and leave the "thingies" out of it.
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Quoting sammywammybamy:


JFV, The only Girl you will ever get will be your 60 year old mother.

Give up my Friend.


only girl to get out of the wrapper was Little Debbie...
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Ok while JFV heads to eHarmony can we please get back on topic.
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Quoting Bipartisanship:
levi, aside from intensity, are you buying into its track?


In general, I like its track better than any other model through 144 hours. Not going to speculate on specifics past 60W yet.
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Quoting Orcasystems:


ummmmmm No comment :)


I agree, keep tour thingie to yourself. lol
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Quoting Orcasystems:


ummmmmm No comment :)


LMAO! Cannot believe I didn't see that coming!
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Quoting ho77yw00d:


HA I am not even going to waste my time!! lol


I wouldnt if I were you... Remember (Closed)!!! LOL
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Quoting ho77yw00d:


HA I am not even going to waste my time!! lol
i like that smart girl

welcome to the blog you can be assured your safe here
Member Since: July 15, 2006 Posts: 174 Comments: 54372

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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.