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 Snowlover123:


Look at Bordonaro's pics of snow. He even says that they're a rare event.

Snow average is 2.5" a winter in the Dallas-Ft Worth, TX area.. Usually a little sleet and a snow flurry or two..

This winter, we had almost 18" of snow, very very rare!! Including a real White Christmas!!
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Thats what I say a few days ago I sent an email to someone that said I was violating a ban and was accusing other people of being me and I told them if they kept up the slandering I would inform admin. I actually did inform admin anyway at that point and asked them to check my IP at the time to confirm I was not and I only had one ID.

It wasn't me. I'll argue with ya straight up.
But I wont go make up stuff.
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Quoting Neapolitan:


Less amazing and impressive was his call for four TCs this month. Of course, it's possible three could form tomorrow, thus allowing the chest-thumping fool to "nail" his forecast...but somehow I'm doubting it. ;-)


tee hee...
Member Since: July 11, 2006 Posts: 14 Comments: 11423
Quoting StSimonsIslandGAGuy:


If it is true, then produce the threatening email. If the email isn't produced, then I guess it's not true.

And now that topic is disposed of.


I'm still waiting for the link to Watts' past.

If the data isn't produced, then I guess it's not true.
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Quoting StSimonsIslandGAGuy:


Actually a majority of years one or more Florida stations reports snow.


Look at Bordonaro's pics of snow. He even says that they're a rare event.
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thank you
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Quoting weathercrazy40:
does this blog refesh automatic or on if you refesh it your self

You have to refresh it your self
or hit your F5 key. that will do it too..

taco :o)
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Quoting FLdewey:


It's automatic.


Tell that to my wimpering F5 key.
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Quoting weathercrazy40:
does this blog refesh automatic or on if you refesh it your self


depends on what browser you use. I use Opera and i can set it to refresh automatically
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Quoting weathercrazy40:
does this blog refesh automatic or on if you refesh it your self

Refresh it yourself :o)!
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Quoting Dennis8:


I a degreed meterologist ( UST-Houston 1989/MSU), no longer working in the field since 2000, who does a little storm spotting for Channel 13 along with the other folks who have a passion for weather. If he talks to me it will be for my area Heights.

If you have an interest contact Gene Hafele at NWS Houston and he can certify you through Skywarn Spotter.



Very interesting, thanks for the info....

Love the Heights
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Quoting Neapolitan:


About every other year on average...


Your source?
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does this blog refesh automatic or on if you refesh it your self
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Quoting StSimonsIslandGAGuy:


No, but when you smear a person by accusing him of threatening you and then refuse to back it up, I think that's really poor. Just plain poor.

And if you answered to yourself, you wouldn't have done that.

And for the record, if you get a threat via email and forward it to admin, admin will make sure that person won't be coming back. Ever.


Let me clear this up.
He did not threaten me physically.
He threatened to report me to the blog cops for something I did not do.
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Quoting brazocane:


I will try and remember to click over at 10:17

May I ask what it is in reference too?


I a degreed meterologist ( UST-Houston 1989/MSU), no longer working in the field since 2000, who does a little storm spotting for Channel 13 along with the other folks who have a passion for weather. If he talks to me it will be for my area Heights.

If you have an interest contact Gene Hafele at NWS Houston and he can certify you through Skywarn Spotter.

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Quoting PensacolaDoug:
What was truly amazing last year was JB's preseason forecast for the deep south. He nailed it in October. Truly an impressive long-range forecast.


Less amazing and impressive was his call for four TCs this month. Of course, it's possible three could form tomorrow, thus allowing the chest-thumping fool to "nail" his forecast...but somehow I'm doubting it. ;-)
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Quoting Chicklit:
Anyway, I'm not a meterologist, and I am not from the NHC, but I did stay at a Comfort Inn last night and I declare 90L moot at this point.
Right we are waiting for 91L, the post were adding to suggested that.
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looking at the Eastern U. S. - AVN Color Infrared Loop that spot offthe east coast seems to be more solid a lot of yellow around the outside and a red center but im just your avg person who like to follow weather
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Quoting Orcasystems:

If you insist on feeding them, you become one... let it go.




Hmmmm...Ya may have a point there..
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Quoting Snowlover123:


Okay, 21 Years ago. That's not exceptional? Does Florida see snow every year?


About every other year on average...
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Quoting Dennis8:


Do you watch Channel 13 ABC weather at 10pm ? I will be the Dennis Raney that Tim Heller will mention.


I will try and remember to click over at 10:17

May I ask what it is in reference too?
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Blog Update!

Invest 90L and several other areas...
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later in the 2nd week of Aug
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Quoting brazocane:


No that is my wifes work and I forgot that pic is actually out of Baytown. Yeah Im under the radar invisibility cloak.


Do you watch Channel 13 ABC weather at 10pm ? I will be the Dennis Raney that Tim Heller will mention.
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Quoting StSimonsIslandGAGuy:


False. Much of northern Florida saw accumulatiing snow in Dec 1989. Far heavier than the flurries reported this past Jan.


Okay, 21 Years ago. That's not exceptional? Does Florida see snow every year?
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Quoting PensacolaDoug:



I don't answer to you,

If you insist on feeding them, you become one... let it go.
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Quoting StormW:
Hey Levi, something I hadn't even thought of yet for some of the inactivity...check this out from Bastardi:

Now, a negative as far as the hurricane season. The Indian Monsoon is farther south than normal, and that is correlated with a weaker-than-normal African wave train. This is interesting to see, given the chill that is taking hold in the Pacific. The IOD is positive, which is usually a wetter-than-normal signal, but this may be dragging a bit because of the "hangover" from the former El Nino.

Now this has some interesting implications, the most obvious being, in a normal season, less development, since the waves would be weaker. However, in this case, there may be another implication... Weaker waves, but with the very warm water, may simply mean later development, and the lack of recurving storms until quite far west. An interesting aspect of the season so far is all three classified systems have been of African origin... not old fronts, or upper lows, etc. The '95 season had much of the action well out over the water, rapid recurve of the intense storms that developed in the heart of the season, and very few storms that stayed on a course mainly west or west-northwest, let's say... like 1933. The scary thing about 1995, and its burst, is if you planted the eastward congregation of tracks 20 degrees west... which is almost what happened in the years 2004, 2005 and 2008...

So this is a negative at this time... but it's not a strong negative, just a bit below. I was just snooping around the Indian Meteorological Dept. site and looking at their comments... so just doing a bit of reflecting on this.




Yeah, very interesting. It is a big point to notice how our first 3 storms were of African origin. That is always a sign of a big season when you get storms in June and July with roots in the wave train. The pattern we're in isn't the best for a mega-season like 2005 in terms of numbers, but it is lined up to be a very bad season for landfalls.
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Storm W you still think August is going to be a busy month?Seems like the models are starting to back off of development.
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That's very interesting storm. Thanks for posting that.
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Quoting Tazmanian:
90L RIP


Do we have a third?
Member Since: July 11, 2006 Posts: 14 Comments: 11423
Quoting Dennis8:


Thanks..is that your home? You in League City? The Houston NWS used to office there and is in Dickinson now..correct?


No that is my wifes work and I forgot that pic is actually out of Baytown. Yeah Im under the radar invisibility cloak.
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Quoting PensacolaDoug:
What was truly amazing last year was JB's preseason forecast for the deep south. He nailed it in October. Truly an impressive long-range forecast.


Actually, he nailed it back in July and renewed it in October.
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Quoting StSimonsIslandGAGuy:


If it is true, then produce the threatening email. If the email isn't produced, then I guess it's not true.

And now that topic is disposed of.



I don't answer to you,
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Quoting Chicklit:
Anyway, I'm not a meterologist, and I am not from the NHC, but I did stay at a Comfort Inn last night and I declare 90L moot at this point.


I'm not a doctor but I play one on tv lol.
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Quoting StormW:


Yes, I am.
Why ask such a question, I do not think any reputable forecater changes his mind on a whole season from breakfast to after dinner, do you?
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ok storm ill take ya word for it cuz i do take ya advise over and over again.
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What was truly amazing last year was JB's preseason forecast for the deep south. He nailed it in October. Truly an impressive long-range forecast.
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3 thing too watch

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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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