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 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: 178 Comments: 56141
Quoting HurricaneSwirl:


Orca, please cast that "thingie" elsewhere.


ummmmmm No comment :)
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189. xcool
sammywammybamy lololol
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Quoting MiamiHurricanes09:
Look at post 169....LMAO


I saw that.. threw me off thinking JFV... Pretty sure ho77yw00d is a woman...couldn't see how that would interest someone who has not reached puberty.
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I say maybe 90L will steal the convection from the wave behind it looking at the sat loop (floater loop) I can see that the convection is not being pulled off of 90L but being pulled off of the wave and pulled in to 90L so i think that maybe the two will merge but 90L will win the battle
anyway I am going to take a shower so see ya all in about 30 mins
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Quoting MiamiHurricanes09:
Look at post 169....LMAO


I'm dyin here!!! LOL!!
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Quoting Bipartisanship:
ho77, are you dating?


i believe your typing to a young miss
i don't think they
may have been the right words
that your lookin for
Member Since: July 15, 2006 Posts: 178 Comments: 56141
Quoting Orcasystems:


Swearing... Caps...Geeze...
JFV?


Orca, please cast that "thingie" elsewhere.
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178. xcool
lmao
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Quoting Orcasystems:


Swearing... Caps...Geeze...
JFV?
Look at post 169....LMAO
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Quoting Bipartisanship:
ho77, are you dating?


Now this could get ugly... well at least half of it... LMAO
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Quoting Bipartisanship:


DAMMIT,W HAT HAPPENED, WHAT KILLED IT, LEVI??? GEEZE.
calm down take a prozac and wait for the better run at 00z
Member Since: July 15, 2006 Posts: 178 Comments: 56141
Quoting Orcasystems:


I actually knew that :)
StormW gave us lessons on it a few years ago.

But I was pretty sure thats basically what I said... with out the big words... tracks were more southern and the models were decreasing the intensity.

I guess I could have said Decreasing Intensity and the Models moving more southerly?
Looks like earthly been spending time on WIKI....lol
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Quoting Bipartisanship:


DAMMIT,W HAT HAPPENED, WHAT KILLED IT, LEVI??? GEEZE.


Swearing... Caps...Geeze...
JFV?
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Quoting Orcasystems:


I actually knew that :)
StormW gave us lessons on it a few years ago.

But I was pretty sure thats basically what I said... with out the big words... tracks were more southern and the models were decreasing the intensity.

I guess I could have said Decreasing Intensity and the Models moving more southerly?


LOL I was just playing on the original comment.. Hopefully someone learned something... I knew you knew but was using your title as a play on words....

Never mind it didnt translate and I fail at my attempt at tropical humor.. :)
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Quoting earthlydragonfly:


I was just talking about how the intensity of a formed hurricane will be effected by the rotation of the earth.....

Not only will the Coriolis effect will aid in the creation of storms that get above about the 5N mark... The Coriolis effect also will give a storm more tendency to move north as the storm strengthen.. the stronger the storm the stronger the tendency for the storm to want to travel in a more northerly direction.. Simply it makes the storms want to make a right hand turn because of the correlation of the storms rotation and the rotation of the earth.. (a spinning object on top of a spinning object..)

Of course I could be full of manure.. I am not a MET. But did stay at a Holiday Inn Express last night.

You are absolutely correct.. It is a torquing effect.
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Quoting HurricaneSwirl:


No, better yet, "thing"-caster.


Thingie... not thing :)
More of a compound word :)
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Quoting earthlydragonfly:


I was just talking about how the intensity of a formed hurricane will be effected by the rotation of the earth.....

Not only will the Coriolis effect will aid in the creation of storms that get above the 5N mark... The Coriolis effect also will give a storm more tendency to move north as the storm strengthen.. the stronger the storm the stronger the tendency for the storm to want to travel in a more northerly direction.. Simply it makes the storms want to make a right hand turn because of the correlation of the storms rotation and the rotation of the earth.. (a spinning object on top of a spinning object..)

Of course I can be full of manure.. I am not a MET. But did stay at a Holiday Inn Express last night.


I actually knew that :)
StormW gave us lessons on it a few years ago.

But I was pretty sure thats basically what I said... with out the big words... tracks were more southern and the models were decreasing the intensity.

I guess I could have said Decreasing Intensity and the Models moving more southerly?
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18z GFS keeps 90L west and weak.

Day 9:

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Quoting MiamiHurricanes09:
Doesn't look like a recurvature will take place.
The low appears through the Florida straights/northern Cuba...interesting?

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I just put my computer on Z time. lol
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162. xcool
lmao GFS
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161. xcool
MiamiHurricanes09 .nope
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Can someone post the link for the 18z gfs,thanks.
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Quoting Orcasystems:


Levi... is that "thing" off Georgia one of those home grown thingies you were writing about the other day?


Yup, sure is. I would be concerned about it if the longwave trough was lifting out of the NE US instead of digging in....but as it is that feature will start to be lifted out tomorrow and get baroclinically influenced, so not a significant threat for tropical development in my mind. However, you can see how much convection these old fronts want to blow up over the exceptionally warm water, which is why I have been mentioning them as a potential concern.
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Quoting xcool:


180hr
Doesn't look like a recurvature will take place.
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Quoting HurricaneSwirl:


Georgia-caster



No, better yet, "thing"-caster.
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Quoting Orcasystems:


Huh?


I was just talking about how the intensity of a formed hurricane will be effected by the rotation of the earth.....

Not only will the Coriolis effect will aid in the creation of storms that get above about the 5N mark... The Coriolis effect also will give a storm more tendency to move north as the storm strengthen.. the stronger the storm the stronger the tendency for the storm to want to travel in a more northerly direction.. Simply it makes the storms want to make a right hand turn because of the correlation of the storms rotation and the rotation of the earth.. (a spinning object on top of a spinning object..)

Of course I could be full of manure.. I am not a MET. But did stay at a Holiday Inn Express last night.
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Quoting Orcasystems:


Levi... is that "thing" off Georgia one of those home grown thingies you were writing about the other day?


Georgia-caster
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I love football and weather maybe by the time football season starts the tropics will start too...(I know it has already started as far as the tropics but I mean really start to heat up) ya know?
Member Since: July 3, 2010 Posts: 0 Comments: 427
Quoting Hardcoreweather2010:


It was a joke but I guess that went right over your head Mr Personality :)


Well ya coulda at least got the first name right, Bobby Hebert is the sportscaster lol.

Just messin around.
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Quoting Levi32:
18z GFS....back onboard:

180 hours:



Levi... is that "thing" off Georgia one of those home grown thingies you were writing about the other day?
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150. xcool


180hr
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"Hebert" in a Box Suite ?
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18z GFS....back onboard:

180 hours:

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145. xcool


162hr'


18z
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Quoting Hardcoreweather2010:


It was a joke but I guess that went right over your head Mr Personality :)


Sorry, my mistake, I missed it, you're right.. you are a joke

Umm I mean Joker
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Quoting Tropicsweatherpr:
Levi, do you think the wave behind 90L gets tagged as 91L and they drop 90L? Or regardless, 90L stays?


I think they will wait to see if the two circulations combine. 90L still has a far better spin than the wave behind, and it's not going to just go *poof* and disappear. We'll have to see how they interact with each other when they get in close proximity. 90L's circulation may even end up being dominant over the wave behind. For now, leaving 90L labeled the way it is is the way to go.
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And he was a NWS & NHC forecaster
so it does involve the tropics
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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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