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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Teddy as big as that circle is they may not have to move it
Member Since: July 18, 2009 Posts: 1 Comments: 994
Thanks SouthALWX.
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Quoting KoritheMan:


IIRC, they forecast a hurricane for the Gulf Coast in September of last year. And obviously, that never materialized.

I always take them with a huge grain of salt.


they pretty good for planting a garden tho lol
Member Since: July 18, 2009 Posts: 1 Comments: 994
to the person who asked why hot towers were called "hot" it is because they are hot in comparison to the height they are at (as air rises it cools) the reason they are different is because they reach the top of the troposphere which has decreasing temps with height and reaches into the stratosphere where it is reversed. They have to be exceptionally warm to rise through any of the stratosphere
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Quoting KerryInNOLA:
The Farmer's Almanac is predicting a hurricane threat for the Southeast Coast for Aug 24-27th. They don't say how severe it will be, but their forecasts are usually accurate. They don't say which model ensemble they use, but it is obviously cutting edge technology. I suspect they are using the new Asian Model developed by Dr Wang's group.


IIRC, they forecast a hurricane for the Gulf Coast in September of last year. And obviously, that never materialized.

I always take them with a huge grain of salt.
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936. xcool


update

Member Since: September 26, 2009 Posts: 2 Comments: 15684
bb when the two comes out
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Quoting KerryInNOLA:
The Farmer's Almanac is predicting a hurricane threat for the Southeast Coast for Aug 24-27th. They don't say how severe it will be, but their forecasts are usually accurate. They don't say which model ensemble they use, but it is obviously cutting edge technology. I suspect they are using the new Asian Model developed by Dr Wang's group.
lo0l
Member Since: September 2, 2007 Posts: 0 Comments: 1092
Think they'll save a few finger strokes and just relocate 90L to the African wave.
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Quoting EricSFL:


buenas noches!


cio
Member Since: July 1, 2005 Posts: 10 Comments: 1683
The Farmer's Almanac is predicting a hurricane threat for the Southeast Coast for Aug 24-27th. They don't say how severe it will be, but their forecasts are usually accurate. They don't say which model ensemble they use, but it is obviously cutting edge technology. I suspect they are using the new Asian Model developed by Dr Wang's group.
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Quoting truecajun:
bonne nuit everyone


buenas noches!
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Quoting will45:


yea at least the Navy site still has it listed


Granted, 90L won't be at 20%. It will be the secondary wave, to the east.
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bonne nuit everyone
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927. xcool



Little better 90l
Member Since: September 26, 2009 Posts: 2 Comments: 15684
Quoting KoritheMan:


I see absolutely no reason why it wouldn't remain at 20%.


yea at least the Navy site still has it listed
Member Since: July 18, 2009 Posts: 1 Comments: 994
Quoting EricSFL:


ahhh, that's what i figured
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Quoting msgambler:
Nope, poker time is over. Can't see the screen anymore....LOL


night
Member Since: July 1, 2005 Posts: 10 Comments: 1683
Quoting xcool:
I wouldn't be suprised if no yellow on map 2am .i have that feel


I see absolutely no reason why it wouldn't remain at 20%.
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Quoting msgambler:
Alright everyone, coffee from this morning is wearing off and meds from this evening are kicking in. I'm out, so everyone have a good night and we'll see ya tomorrow.


i'm in the same boat. took benadryl so i could knock myself out early in order to wake early. i'm trying to train my body into the school clock of 7 am to rise adn 10pm to fall. school starts in a week here. yaaaay!!!!!!!!!!!!
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Quoting earthlydragonfly:


ur going to play poker.... dont lie.. lol gw..... oooooppps i mean gn
Nope, poker time is over. Can't see the screen anymore....LOL
Member Since: February 27, 2010 Posts: 0 Comments: 1125
920. xcool
guess i find out like a fool at 2am
Member Since: September 26, 2009 Posts: 2 Comments: 15684
Quoting truecajun:


well, they do say go the tropics for romance

so what are these 2 going to do? if they combine, is landfall likely or will it be too stong, adn head northeast (fish). still too early to speculate??
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Quoting msgambler:
Alright everyone, coffee from this morning is wearing off and meds from this evening are kicking in. I'm out, so everyone have a good night and we'll see ya tomorrow.


ur going to play poker.... dont lie.. lol gw..... oooooppps i mean gn
Member Since: July 1, 2005 Posts: 10 Comments: 1683
nah the yellow will be there
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Quoting EricSFL:


They're having a tropical affair.


well, they do say go the tropics for romance

so what are these 2 going to do? if they combine, is landfall likely or will it be too stong, adn head northeast (fish). still too early to speculate??
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xcool, since they now do the "near 0%" I think it might still be yellow at 2:00.
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Alright everyone, coffee from this morning is wearing off and meds from this evening are kicking in. I'm out, so everyone have a good night and we'll see ya tomorrow.
Member Since: February 27, 2010 Posts: 0 Comments: 1125
912. xcool
I wouldn't be suprised if no yellow on map 2am .i have that feel
Member Since: September 26, 2009 Posts: 2 Comments: 15684
Quoting truecajun:
hello all, so whats up tonight? 90 getting involved with a lady to his east?


They're having a tropical affair.
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Quoting earthlydragonfly:


Ill step in here... (probably should shut up but )

I think everyone here cares about the subject! It is very important... However, we are in the start of hurricane season and right now that is what most want to talk about. But the GW discussions and debates almost have no chance of conclusion in this format. So the ongoing conversations (pointless to many because it is a forgone conclusion that it will not be resolved on this blog) are choking the ability for what most come here for this time of year, Hurricanes, tropical storms and chasing Blobs across the Tropics..... You want to have a great debate on this blog... wait till December. JMHO.

Amen brother!!
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Quoting JFLORIDA:
Well actually beyond the political there are worthwhile climate discussions that need to occur. Let them happen. You dont know where they are going to lead before they start. None of us seem to have that technical a grasp on long range projections anyway.
you are right however when i listen to talk radio anytime someone mentions global change the host shouts them down then hangs up on them and calls them un amercan or loons so sad to hide the trueth because ya lost power
Member Since: September 2, 2007 Posts: 0 Comments: 1092
Quoting earthlydragonfly:


Ill step in here... (probably should shut up but )

I think everyone here cares about the subject! It is very important... However, we are in the start of hurricane season and right now that is what most want to talk about. But the GW discussions and debates almost have no chance of conclusion in this format. So the ongoing conversations (pointless to many because it is a forgone conclusion that it will not be resolved on this blog) are choking the ability for what most come here for this time of year, Hurricanes, tropical storms and chasing Blobs across the Tropics..... You want to have a great debate on this blog... wait till December. JMHO.


It will kick in soon. It always does.

I actually enjoy winter storm discussions more than climate here. But ill leave you to it.

Keep an eye open closer in too.
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hello all, so whats up tonight? 90 getting involved with a lady to his east?
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906. xcool
JLPR2 .90l doom now.i meaning bye
Member Since: September 26, 2009 Posts: 2 Comments: 15684
Quoting JFLORIDA:
Well actually beyond the political there are worthwhile climate discussions that need to occur. Let them happen. You dont know where they are going to lead before they start. None of us seem to have that technical a grasp on long range projections anyway.


totally agree... now where was that blob at.......
Member Since: July 1, 2005 Posts: 10 Comments: 1683
904. xcool
EricSFL .yeah much better.1800 hot cake
Member Since: September 26, 2009 Posts: 2 Comments: 15684
903. xcool
gfs 00
Member Since: September 26, 2009 Posts: 2 Comments: 15684
902. JLPR2
Quoting xcool:



UPDATE




90L seems to be maintaining itself quite nicely with the TW weakening slightly.
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Quoting xcool:
EricSFL .welcome .call hot tower


You mean 1-800-hot-towr. LOL j/k.
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Well actually beyond the political there are worthwhile climate discussions that need to occur. Let them happen. You dont know where they are going to lead before they start. None of us seem to have that technical a grasp on long range projections anyway.
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Well I'm out... I'll leave you gentlemen with this:

Rider University Article

Not directed at anyone... I'm jussayin... ifyaknowhatimsayin.
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897. xcool
EricSFL .welcome .call hot tower
Member Since: September 26, 2009 Posts: 2 Comments: 15684
Quoting earthlydragonfly:


Ill step in here... (probably should shut up but )

I think everyone here cares about the subject! It is very important... However, we are in the start of hurricane season and right now that is what most want to talk about. But the GW discussions and debates almost have no chance of conclusion in this format. So the ongoing conversations (pointless to many because it is a forgone conclusion that it will not be resolved on this blog) are choking the ability for what most come here for this time of year, Hurricanes, tropical storms and chasing Blobs across the Tropics..... You want to have a great debate on this blog... wait till December. JMHO.
I would tend to agree that GW is worth the debate, just not at this time of year. Let the debate start after the season ends.
Member Since: February 27, 2010 Posts: 0 Comments: 1125
Thanks xcool. Excellent information.
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earthly it is kinda a break in the action though
Member Since: September 2, 2007 Posts: 0 Comments: 1092
Quoting msgambler:
Earthly, when does school start down in South FL

aug 23rd
Member Since: July 1, 2005 Posts: 10 Comments: 1683
892. xcool
btwntx08 opps .your rigth
Member Since: September 26, 2009 Posts: 2 Comments: 15684
Quoting JFLORIDA:
Usually the people who don't want to allow talk of GW or climate are those that really don't want reasonable discussion of climate to occur.

They want to maintain it as a political topic outside scientific discourse. Its always a conspiracy or someone else being "political" in an attempt to suppress reasonable discussion.


Ill step in here... (probably should shut up but )

I think everyone here cares about the subject! It is very important... However, we are in the start of hurricane season and right now that is what most want to talk about. But the GW discussions and debates almost have no chance of conclusion in this format. So the ongoing conversations (pointless to many because it is a forgone conclusion that it will not be resolved on this blog) are choking the ability for what most come here for this time of year, Hurricanes, tropical storms and chasing Blobs across the Tropics..... You want to have a great debate on this blog... wait till December. JMHO.
Member Since: July 1, 2005 Posts: 10 Comments: 1683

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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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