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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You think the Carribean AOI could become Invest 91L and perhaps Colin before moving into Central America due to it's 'upgrade'?
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1338. hydrus
....Moisture field looks healthy in the Eastern Atlantic......
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Quoting Snowlover123:
Good Morning!

July was a bust. Let's face it. We had a Tropical Depression and a big thunderstorm classified as "Bonnie." Yippie. And 90L is getting absorbed by another wave, and the wave itself looks disorganized. Yippie.


Your going to be changing your tune shortly.
Member Since: July 8, 2005 Posts: 259 Comments: 24553
Here is a good visible loop. Some turning is seen in the area.

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Member Since: July 8, 2005 Posts: 259 Comments: 24553
WU does not even have 90L up as anything anymore so... RIP 90L
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Quoting jasoniscoolman2010x:
GOOD MORNING TO YOU.


ty :)
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Nothing out there looking too terribly impressive at the moment. Fine with me.
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1326. hydrus
Quoting Snowlover123:
Good Morning!

July was a bust. Let's face it. We had a Tropical Depression and a big thunderstorm classified as "Bonnie." Yippie. And 90L is getting absorbed by another wave, and the wave itself looks disorganized. Yippie.
August will not be a bust. A lot of people wont be disappointed if it is though.
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yea texwarhawk so you think we may get 91L today or tomrrow I think tonight
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I see the carib aoi got bumped to 20% since yesterday.
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No suprise with 90L's deactivation this morning as the disturbance remains very disorganized.
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Quoting btwntx08:
decent vorticity but enlongated


Which means, it's still a tropical wave. I love the voriticy with 97E, though.
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1321. Patrap
Atlantic Low Cloud Image.,,LARGE
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oh yea well and cool I am.... ;)
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Just feekin' fantastic...LOL
Hope you are well and cool this am.
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1317. Patrap
The Pacific has 3 Zones of Tropical responsibility.

East,Central and West.

C,E and W
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Quoting msgambler:
Morning ho77yw00d


good morning how are u?
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Quoting ho77yw00d:
morning all.... what did I miss?
Morning ho77yw00d
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1313. Zegama
Looks like a long game of 'Red Rover' with Africa. Link
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morning all.... what did I miss?
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Good Morning!

July was a bust. Let's face it. We had a Tropical Depression and a big thunderstorm classified as "Bonnie." Yippie. And 90L is getting absorbed by another wave, and the wave itself looks disorganized. Yippie.
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Vorticity seems to try and be tightning up

Link
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Quoting Patrap:


Well than Im gonna go get some surgery and a Bohenor Tan and change professions.

Morn' ms
I see Botox in Pats future...LOL
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1306. Patrap
Quoting earthlydragonfly:


Not sure the boil guys on da side of the road there in the big easy could afford the 50k price tag for the cameo fee.. That is what that chick gets for a vegas cameo in the bars there for 2 hours.


Well then Im gonna go get some surgery and a Boehnor Tan and change professions.

Morn' ms
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Morning Pat
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Quoting Patrap:


Some might pay to see dat now.


Maybe er, we can swing a Snooki does crawdads PPV gig?


Not sure the boil guys on da side of the road there in the big easy could afford the 50k price tag for the cameo fee.. That is what that chick gets for a vegas cameo in the bars there for 2 hours.
Member Since: July 1, 2005 Posts: 10 Comments: 1683
1303. Patrap
A desperately needed weather Image.


Dvorak,



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1301. Patrap
Quoting earthlydragonfly:


Not sure I could see her eating crawfish from a bag and sucken de heads...


Some might pay to see dat now.


Maybe er, we can swing a Snooki does crawdads PPV gig?
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Quoting Patrap:
No way.

...we're about as far from her as one can get,,LOL'

Thankfully


Not sure I could see her eating crawfish from a bag and sucken de heads...
Member Since: July 1, 2005 Posts: 10 Comments: 1683
1298. Patrap
No way.

...we're about as far from her as one can get,,LOL'

Thankfully

Looks Like a Double barrled Low in that pic earthlydragonfly,

Snicker,snookers,..laff

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Quoting Patrap:
Snooki got arrested.

Is that real news..?

Poor Jersey.


She is your new weather girl Pat

Member Since: July 1, 2005 Posts: 10 Comments: 1683
1296. Patrap
Snooki got arrested.

Is that real news..?

Poor Jersey.
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Quoting zoomiami:
Not Ron Magill - reference is to the state of my household - not where I work. LOL

I had the name before they changed theirs.

LOL... I do remember seeing your name before they changed theirs... you gotta love Ron though he is awesome!
Link
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1293. Patrap
Pakistani Rescuers Struggle in Deadly Monsoons

31 July

Rescue workers and troops are struggling Saturday to reach thousands of stranded villagers in northwest Pakistan, following the deadliest monsoon rains to hit the region since 1929.

Authorities say the four days of pounding rain in the Khyber-Pakhtunkhwa province have killed more than 400 people.

Provincial Information Minister Mian Iftikhar Hussain has appealed to the international community for assistance.

Hundreds of homes, dozens of bridges, and massive parcels of agricultural land have been destroyed in the province, including the areas of Peshawar, Swat Valley and the Charsadda district. The main highway to China is under water.

At least 400,000 people have been affected by the flooding.

Meteorologists say more rain is expected in the coming days.
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Quoting aquak9:
cute video, CoolJason. Too bad the storms don't have 100 miles of desert to travel thru.


Looking at the SAL- they might
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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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