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 MiamiHurricanes09:
000
ABNT20 KNHC 302344
TWOAT
TROPICAL WEATHER OUTLOOK
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
800 PM EDT FRI JUL 30 2010

FOR THE NORTH ATLANTIC...CARIBBEAN SEA AND THE GULF OF MEXICO...

A WESTWARD-MOVING TROPICAL WAVE CONTINUES TO PRODUCE DISORGANIZED
SHOWERS AND THUNDERSTORMS OVER THE SOUTHEASTERN AND SOUTH-CENTRAL
CARIBBEAN SEA. LITTLE DEVELOPMENT OF THIS SYSTEM IS EXPECTED
UNTIL IT REACHES THE SOUTHWESTERN CARIBBEAN SEA IN A COUPLE OF DAYS.
THERE IS A LOW CHANCE...10 PERCENT...OF THIS SYSTEM BECOMING A
TROPICAL CYCLONE DURING THE NEXT 48 HOURS.

A SMALL AREA OF DISTURBED WEATHER OVER THE EASTERN ATLANTIC ABOUT
700 MILES SOUTHWEST OF THE CAPE VERDE ISLANDS CONTINUES TO LOSE
ORGANIZATION AS IT INTERACTS WITH A LARGER TROPICAL WAVE A FEW
HUNDRED MILES SOUTH-SOUTHEAST OF THE CAPE VERDE ISLANDS.
DEVELOPMENT OF EITHER SYSTEM...IF ANY...SHOULD BE SLOW TO
OCCUR...AND THERE IS A LOW CHANCE...20 PERCENT...OF TROPICAL
CYCLONE FORMATION IN THIS AREA DURING THE NEXT 48 HOURS.

ELSEWHERE...TROPICAL CYCLONE FORMATION IS NOT EXPECTED DURING THE
NEXT 48 HOURS.

$$
FORECASTER BEVEN


How come yours updates so much faster than mine XD, I'm F5ing practically as a type and it's still on the 2PM outlook for me.
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Looks like the larger tropical wave going to be our system. 90L and the large tropical wave are already interacting per TWO.
Member Since: July 8, 2005 Posts: 259 Comments: 24512
Quoting MiamiHurricanes09:
Will it verify? Oh, the suspense! LOL.
Nuthin'. Oh well. Be back later.
Member Since: September 2, 2009 Posts: 130 Comments: 21194
000
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Quoting robj144:


I just ate.. I wasn't quite that Hungary, just a little Budapest. :)

Kinda funny, I don't know if WKC will think so, but as the capital you were more hungry or not so much :)
Member Since: Posts: Comments:
000
ABNT20 KNHC 302344
TWOAT
TROPICAL WEATHER OUTLOOK
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
800 PM EDT FRI JUL 30 2010

FOR THE NORTH ATLANTIC...CARIBBEAN SEA AND THE GULF OF MEXICO...

A WESTWARD-MOVING TROPICAL WAVE CONTINUES TO PRODUCE DISORGANIZED
SHOWERS AND THUNDERSTORMS OVER THE SOUTHEASTERN AND SOUTH-CENTRAL
CARIBBEAN SEA. LITTLE DEVELOPMENT OF THIS SYSTEM IS EXPECTED
UNTIL IT REACHES THE SOUTHWESTERN CARIBBEAN SEA IN A COUPLE OF DAYS.
THERE IS A LOW CHANCE...10 PERCENT...OF THIS SYSTEM BECOMING A
TROPICAL CYCLONE DURING THE NEXT 48 HOURS.

A SMALL AREA OF DISTURBED WEATHER OVER THE EASTERN ATLANTIC ABOUT
700 MILES SOUTHWEST OF THE CAPE VERDE ISLANDS CONTINUES TO LOSE
ORGANIZATION AS IT INTERACTS WITH A LARGER TROPICAL WAVE A FEW
HUNDRED MILES SOUTH-SOUTHEAST OF THE CAPE VERDE ISLANDS.
DEVELOPMENT OF EITHER SYSTEM...IF ANY...SHOULD BE SLOW TO
OCCUR...AND THERE IS A LOW CHANCE...20 PERCENT...OF TROPICAL
CYCLONE FORMATION IN THIS AREA DURING THE NEXT 48 HOURS.

ELSEWHERE...TROPICAL CYCLONE FORMATION IS NOT EXPECTED DURING THE
NEXT 48 HOURS.

$$
FORECASTER BEVEN
Member Since: September 2, 2009 Posts: 130 Comments: 21194
Quoting ElConando:


Has the wave in the E Caribbean improved in any way to warrant that in your opinion?
The closer it gets to the more favorable upper level winds in the western Caribbean the higher the chances for development. It has improved on satellite somewhat and vorticity is a little bit better this evening.
Member Since: September 2, 2009 Posts: 130 Comments: 21194
Quoting MiamiHurricanes09:
I would put 4 yellow circles on the NHC map.

1 near the stalled frontal boundary disturbance -- Near %0 chance.
1 near the tropical wave by Honduras -- 10% chance.
1 near the tropical wave by the Lesser Antilles -- 20% chance.
1 near 90L -- 20% chance.

My opinion only; not official information.
Will it verify? Oh, the suspense! LOL.
Member Since: September 2, 2009 Posts: 130 Comments: 21194
329. xcool
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Quoting MiamiHurricanes09:
I would put 4 yellow circles on the NHC map.

1 near the stalled frontal boundary disturbance -- Near %0 chance.
1 near the tropical wave by Honduras -- 10% chance.
1 near the tropical wave by the Lesser Antilles -- 20% chance.
1 near 90L -- 20% chance.

My opinion only; not official information.


Has the wave in the E Caribbean improved in any way to warrant that in your opinion?
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Quoting MiamiHurricanes09:
Take a look at steering currents, this system will get shot up towards the NE tomorrow.


And to add I doubt it becomes anything of significance either.
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Quoting jasoniscoolman2010x:
something else to watch

Hot Towers j/k no joke, I'm watching it I live in Grand Cayman.
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For those really interested in GW/CC and CO2, this is a must see video. It basically explains the best science we have today and in delightful way.

Link
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Quoting STXpat:
It was some thing about lower life forms...are we the highest?

yeah we are the highest
that we know of
but like all things
we are nothing
without the lower
just like a house of sticks
remove the foundation
and the whole house
comes crashing down
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Quoting StormW:


"Something Smart"! (j/k)

I see it appears that the MJO is trying to make a comeback, based on the velocity map a few posts back. Goes along with what we've been preachin'


Pass the collection plate ...
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Yes I realize this is more than 12 hours old, but it is the latest I see.

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Quoting Jeff9641:
Looks like Colin in the next couple of days if not sooner off the SE US and whatever developes there will move W or WSW toward FL.
Take a look at steering currents, this system will get shot up towards the NE tomorrow.
Member Since: September 2, 2009 Posts: 130 Comments: 21194
It was some thing about lower life forms...are we the highest?
Member Since: September 18, 2008 Posts: 0 Comments: 36
Ok guys do you wnat me to post pictures of my dogs at the doggie park?

It seems 90L is a little more south. If it develops that would put the Gulf in play. Right?
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Quoting Jeff9641:
Looks like Colin in the next couple of days if not sooner off the SE US and whatever developes there will move W or WSW toward FL.


Why not GA?
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I would put 4 yellow circles on the NHC map.

1 near the stalled frontal boundary disturbance -- Near %0 chance.
1 near the tropical wave by Honduras -- 10% chance.
1 near the tropical wave by the Lesser Antilles -- 20% chance.
1 near 90L -- 20% chance.

My opinion only; not official information.
Member Since: September 2, 2009 Posts: 130 Comments: 21194
I brought this over from the other blog.


An observation:

This lifted from post 1935 By JFLORDIA:

The insult was yours my friend.


But on post 1886:

He writes:

Political posters hope to silence all discussion on a weather site - thats just not going to happen. Many of you are from rural areas and certainly have strong political opinions on the economic implications of climate change.
Thats not science and this is a science related site.


Question: Am I the only one who sees the insult in that post?

If ya don't, re-read the second sentence.

And if anybody thinks JFLORIDA ought to read this. It may need to be re-posted as I'm sure he has me blocked.

Thanks all.
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Quoting MiamiHurricanes09:
I ain't seeing any area of low pressure developing especially with the very high pressures across the system's location.


its just everyday thunderstorms
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Quoting MiamiHurricanes09:
The reading of 1009mb in the northern quadrant is obviously suspect considering every other observation in and around the system consists of pressures above 1014mb with several reaching 1016mb.

i am seeing the same thing looks to be headed towards florida
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Quoting Seflhurricane:
looking at satelite and surface observations the area of disturbed weather of the se coast is developing a low pressure area
I ain't seeing any area of low pressure developing especially with the very high pressures across the system's location.
Member Since: September 2, 2009 Posts: 130 Comments: 21194
I'm sure that man has had an incredible impact on this worlds climate, but let's not forget that Mother Nature can do in one instant what took us a hundred years. Let's hope she behaves.
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looking at satelite and surface observations the area of disturbed weather of the se coast is developing a low pressure area
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Quoting zoomiami:
My husband says the safest place to be is where ever the models picked first for landfall -- you can be sure it won't be there!

That is probably a very true statement. They need time to lock onto the system.
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My husband says the safest place to be is where ever the models picked first for landfall -- you can be sure it won't be there!
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AOI

AOI

AOI

AOI

AOI

TS BUSTED FORECAST ALIBI
Member Since: October 1, 2007 Posts: 81 Comments: 26511
Quoting Orcasystems:


We have warned you before about using logic and facts... thats what gives you the headaches.. now stop it :)


sorry, I forgot!
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Well well well look at that...24 hours later and the models shifted south. Big surprise there (sarcasim). Models totally different today.
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Quoting KEEPEROFTHEGATE:
be good zoo shhh i like watchin them make fools of themselves and its kinda funny too


ROFLMAO
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Quoting hunkerdown:
will it lift out or get left behind...
Steering currents in the area are very weak and as noted on satellite it appears that the system is drifting towards the SE, but that just could be an optical illusion as 20 knots of shear coming from the north towards the south may give you that idea. Steering currents should strengthen considerable pushing this system towards the NE in about 24 hours according to the latest forecast PSU e-WALL steering currents. So, the system should start lifting out tomorrow.
Member Since: September 2, 2009 Posts: 130 Comments: 21194
Where is the packing tap for my head.. GW again.. Tropics gone fishing
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Quoting StSimonsIslandGAGuy:


Judging by the emails he sends me, I wouldn't assume anything about his orientation.

+37
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Quoting wunderkidcayman:
guys 90L will develop and the wave behind it will aid to that also I see a track taking 90L into the Caribbean I have more to say after I eat I am very very hungary


I just ate.. I wasn't quite that Hungary, just a little Budapest. :)
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Sorry JF. Seriously, just an attempt @ humor.
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We've had anomalous upper easterlies so far this year, for the last several months in a row. Wind shear has been below normal all year long so far.

And wow look at the the last 30 days showing a jet of upper easterlies colliding with a jet of westerlies in the central Pacific. That's the sink hole of death for the tropical season out there! When upper air converges that strongly, it races downward, and sinking air like that puts a strong cap on convection.



Wind shear = still below normal:

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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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