Little change to 90L; new African tropical wave is worth watching

By: Dr. Jeff Masters , 8:53 PM GMT on July 30, 2010

Share this Blog
3
+

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

Reader Comments

Comments will take a few seconds to appear.

Post Your Comments

Please sign in to post comments.

or Join

Not only will you be able to leave comments on this blog, but you'll also have the ability to upload and share your photos in our Wunder Photos section.

Display: 0, 50, 100, 200 Sort: Newest First - Order Posted

Viewing: 1591 - 1541

Page: 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 | 26 | 27 | 28 | 29 | 30 | 31 | 32 | 33 | 34 | 35Blog Index

Quoting bwt1982:


LOL! your not talking about the Atlantic basin are you? 8 in August with the season being as dead as it is? LOL! enough wishcasting!


Seasons are usually always dead until this month, I don't know where you get your history from. Clearly things are going to become very active.
Member Since: Posts: Comments:
Quoting extreme236:
I stick by my prediction of 18-21 named storms. I can see various paths to getting this number.

6 in August, 6 in September, 3 in October, and just 1 in November or post-season would reach 18.

I'm also sticking by my prediction of 18-11-6 from back in May.
Member Since: Posts: Comments:
1589. bwt1982
Quoting Neapolitan:


I think you're way too low on total storms; I go with seven or eight for the month, with four or five of them hurricanes, including a pair of majors.

LOL! your not talking about the Atlantic basin are you? 8 in August with the season being as dead as it is? LOL! enough wishcasting!
Member Since: Posts: Comments:
Quoting 1900hurricane:

Exactly. 2005 didn't have super-bursts, but it did have endurance. 2005 started early, ended late, and never stopped in between. The record for most in a month is 8, which actually goes to September of.....2002! XP


That number was actually tied in 2007, but those storms were rather weak.
Member Since: Posts: Comments:
Quoting Snowlover123:


I think that you're mistaken...


Meteorology and climatology back up my opinion; what do you have? ;-)
Member Since: Posts: Comments:
1584. Zegama
Thanks for all the good scientific speculation everyone. I'll be back tonight to catch up. Have a good afternoon.
Member Since: Posts: Comments:
Quoting extreme236:
The thing about 2005's activity was that it was fairly evenly spread throughout the months of the hurricane season. August and September each had only 5 named storms in 2005.


Exactly. 2005 didn't have super-bursts, but it did have endurance. 2005 started early, ended late, and never stopped in between. The record for most in a month is 8, which actually goes to September of.....2002! XP
Member Since: Posts: Comments:
1969. Notice the distinct (and somewhat familiar) lack of activity until the second week of August...then The Unleashing.

BOOM goes the dynamite...

Image source: Wikipedia - 1969 Atlantic Hurricane Season

Now, I'm not saying we're in for the same; I'm just highlighting one particular possibility.
Member Since: Posts: Comments:
1581. Drakoen
Member Since: Posts: Comments:
I might be channeling my inner reedzone by going out on such a limb, but if the GFS verifies and we see 4 named storms in the first half of August, the second half in theory would be just as active or more active as it approaches the peak.
Member Since: Posts: Comments:
1578. Drakoen
Quoting extreme236:
October was the most active month of the 2005 hurricane season in terms of number of named storms. 7 formed during the month.


Which is exactly why we can't rule out this season. We've already had two named storms and it looks like the months ahead will be very active. I may lower my season totals come August but it won't be by much.
Member Since: Posts: Comments:
I stick by my prediction of 18-21 named storms. I can see various paths to getting this number.

6 in August, 6 in September, 3 in October, and just 1 in November or post-season would reach 18.
Member Since: Posts: Comments:
1576. KEEPEROFTHEGATE (Mod)
lol
Member Since: July 15, 2006 Posts: 169 Comments: 53296
October was the most active month of the 2005 hurricane season in terms of number of named storms. 7 formed during the month.
Member Since: Posts: Comments:
Ya know what they say...77's alot better than that other number!
Member Since: Posts: Comments:
Quoting Neapolitan:


I think you're way too low on total storms; I go with seven or eight for the month, with four or five of them hurricanes, including a pair of majors.


I think that you're mistaken...
Member Since: Posts: Comments:
1571. bwt1982
Tropics are dead as usual! With 2010 being a bust year for the tropics and it being a very dry wet season here in Florida, starting to wonder whats going on with mother nature. LOL
Member Since: Posts: Comments:
Quoting gordydunnot:
Oh, thanks my bad. It wasn't even funny I guess.


rofl...back to weather...boys........
Member Since: July 3, 2010 Posts: 0 Comments: 427
The thing about 2005's activity was that it was fairly evenly spread throughout the months of the hurricane season. August and September each had only 5 named storms in 2005.

Member Since: Posts: Comments:
Quoting superweatherman:
Think there going to be 4-5 storms this August.. With 2-3 major hurricanes. and one of them striking the US as a major or a Cat 2


I think you're way too low on total storms; I go with seven or eight for the month, with four or five of them hurricanes, including a pair of majors.
Member Since: Posts: Comments:
Oh, thanks my bad. It wasn't even funny I guess.
Member Since: Posts: Comments:
Quoting gordydunnot:
Did he say keep the focus on boys.


lmao I just saw this... too funny
Member Since: July 3, 2010 Posts: 0 Comments: 427
1565. Drakoen
Also have to keep in mind that the MJO is variable, hence, why we can see a little upward motion with our AOI SW of the CV islands.
Member Since: Posts: Comments:
Quoting extreme236:
I believe we could see several named storms this month IMO.

I'll believe it when I see it. :P
Member Since: Posts: Comments:
Quoting gordydunnot:
Did he say keep the focus on boys.



no, I said keep the focus on weather, boys. Haven't you been to school? its called correct usage of comma placement and grammar structure.
Member Since: Posts: Comments:
Quoting superweatherman:
Think there going to be 4-5 storms this August.. With 2-3 major hurricanes. and one of them striking the US as a major or a Cat 2

That is a definite possibility!!!
Member Since: Posts: Comments:
I believe we could see several named storms this month IMO.
Member Since: Posts: Comments:
rumblin bumblin stumblin strugglin invests again. what's new this season....
Member Since: Posts: Comments:
Quoting mfaria101:
Death Spiral of the oceans....
This doesn't look good,
Link


Pretty much what Dr. Masters wrote in the current blog topic:

"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...I plan to discuss this paper next week."
Member Since: Posts: Comments:
Think there going to be 4-5 storms this August.. With 2-3 major hurricanes. and one of them striking the US as a major or a Cat 2
Member Since: Posts: Comments:
1557. Drakoen
Quoting Drakoen:


Yes it is an eastward propagating wave. Atmospheric circulations determine where the upward or downward phase is present. The upward motion will favor 200mb divergence aloft, while the downward motion will favor upper level convergence.


Sea-surface temperatures also help dictate where the MJO will be most concentrated.
Member Since: Posts: Comments:
Quoting mfaria101:
Death Spiral of the oceans....
This doesn't look good,
Link


The strongest La Nina since never is coming on? Perfect time to make this... <_<
Member Since: Posts: Comments:
16 days, yikes for PR and DR if that were to verify



Member Since: Posts: Comments:
1553. Drakoen
Quoting bappit:

The MJO is a wave moving through the atmosphere. I guess it has to start somewhere or something triggers it.


Yes it is an eastward propagating wave. Atmospheric circulations determine where the upward or downward phase is present. The upward motion will favor 200mb divergence aloft, while the downward motion will favor upper level convergence.
Member Since: Posts: Comments:
Did he say keep the focus on boys.
Member Since: Posts: Comments:
1551. KEEPEROFTHEGATE (Mod)
hello 77
Member Since: July 15, 2006 Posts: 169 Comments: 53296
I think that sonn models will change to development of ex-90Lpossible reactivate/or pre-91L and tracks further west further into the caribbean
Member Since: June 13, 2009 Posts: 2 Comments: 11141
:(
Quoting DDR:
Someone keeps hiding your posts ho77ywood,lol.
In the meantime its been rainy now in North Trinidad for 3 days.

:(
Member Since: July 3, 2010 Posts: 0 Comments: 427
1548. bappit
Quoting Drakoen:


The MJO is simply areas where convection is enhanced or suppressed. The MJO is governed by atmospheric circulations coupled with convection and is influenced by ENSO conditions.

The MJO is a wave moving through the atmosphere. I guess it has to start somewhere or something triggers it.
Member Since: Posts: Comments:
Quoting Boca:
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.

I am confused. Is it in the WET phase or the dry phase?

MJO DRY PHASE-is when air is subsiding, or sinking, in the atmosphere. This inhibits TC development. Warm air sinks, drying out, like an area of High Pressure. We are currently in this phase.

MJO WET PHASE-is where moist, warm tropical air rises due to the excessive heat. Rising air creates a general area of disturbed weather, creating lower pressures, rising air and development of TC in the MDR.

I am not a meteorologist, I have followed weather for 42 yrs. My strengths are winter storms and severe weather.

I would really be very concerned about the next MJO wet phase, which is scheduled to start on or around 8-8-10..
Member Since: Posts: Comments:
1546. SLU
Quoting DDR:
Someone keeps hiding your posts ho77ywood,lol.
In the meantime its been rainy now in North Trinidad for 3 days.


Is it raining in Port of Spain?

I'll be coming to take up residence in Trinidad from late August.
Member Since: Posts: Comments:
Death Spiral of the oceans....
This doesn't look good,
Link
Member Since: Posts: Comments:
1544. Drakoen
It looks like the GFS is seeing the "season"
Member Since: Posts: Comments:
Hey to all the nerds, ho77lywood is probably a dude pretending to be a girl lol, even if shes not, this a weather blog not an online dating service, keep the focus on weather, boys, shall we? lolol
Member Since: Posts: Comments:
Quoting OneDrop:
Hollywood, Redfish are one of my favorites. Just got done cleaning a huge amount of snapper from fishing last night. Where did you catch your redfish?


this little place called bunchy beach they built new little docks and its back country so with my powerpro I cast a country mile and just sat my pole down and then it was singing (love that sound) but yea it was my first time there and I saw 2 at least 40" snook I caught trout (too small) but it is def a great fishing spot!
Member Since: July 3, 2010 Posts: 0 Comments: 427
Quoting Hurricanes101:


It develops 4 systems

SW Caribbean, 90L and 2 waves behind 90L


If that were to verify, we'd have an average August's activity in just around two weeks time...and who knows what other systems could pop up.
Member Since: Posts: Comments:

Viewing: 1591 - 1541

Page: 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | 15 | 16 | 17 | 18 | 19 | 20 | 21 | 22 | 23 | 24 | 25 | 26 | 27 | 28 | 29 | 30 | 31 | 32 | 33 | 34 | 35Blog Index

Top of Page

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.

Local Weather

Scattered Clouds
58 °F
Scattered Clouds