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 JLPR2:


yeah, all of that energy will have to go with one of the two, sooner or later.


There's also the possibility that we don't see development until the second week of August, when the upward MJO will be in full swing.
Member Since: Posts: Comments:
989. xcool
yeah sea fish
Member Since: September 26, 2009 Posts: 2 Comments: 15672
Quoting xcool:
how about big fish from bk


That's what the CMC is having!
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986. JLPR2
Quoting KoritheMan:


This is such a large area of precipitation and vorticity that it's going to be awhile, possibly days, before anything really consolidates here.


yeah, all of that energy will have to go with one of the two, sooner or later.
Member Since: September 4, 2007 Posts: 7 Comments: 8698
985. xcool
how about big fish from bk
Member Since: September 26, 2009 Posts: 2 Comments: 15672
Quoting EricSFL:
Whoever eats that might have to use the restroom immediately afterwards. lol


Restroom-Caster! Haha...
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Quoting JLPR2:
As of now its obvious not much is going on since we are talking about tacos. LOL!
Now I'm hungry :(



This is such a large area of precipitation and vorticity that it's going to be awhile, possibly days, before anything really consolidates here.
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982. xcool
lmao
Member Since: September 26, 2009 Posts: 2 Comments: 15672
981. JLPR2
As of now its obvious not much is going on since we are talking about tacos. LOL!
Now I'm hungry :(

Member Since: September 4, 2007 Posts: 7 Comments: 8698
big mommy wave: plll ppppllllll

NHC: Excuse me!

big mommy wave: sorry, it was the bean burrito I just ate...
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979. xcool
:)))
Member Since: September 26, 2009 Posts: 2 Comments: 15672
Quoting JLPR2:


the taco in the middle is calling me.
LOL!
I dont care if I have to use the restroom afterwards, I'll happily go. XD


Same. XD
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977. JLPR2
Quoting EricSFL:
Whoever eats that might have to use the restroom immediately afterwards. lol


the taco in the middle is calling me.
LOL!
I dont care if I have to use the restroom afterwards, I'll happily go. XD
Member Since: September 4, 2007 Posts: 7 Comments: 8698
Quoting xcool:
CARIBBEAN MAYBE 91L


I think so as well.
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Quoting KerryInNOLA:


:(


Look, man. If you want to believe them, then by all means. I'm not trying to belittle that at all. I'm sorry if I came off as condescending. I'm just a rather strong skeptic with regards to many things. Oh, and a cynic too.
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Now, I will say one thing ... pleasant forecast for the climatological peak of hurricane season ... I want to see how that goes :)
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973. xcool
CARIBBEAN MAYBE 91L
Member Since: September 26, 2009 Posts: 2 Comments: 15672
hot and scattered storms in late july? Im going to go out on a limb and make the same forecast ... for the end of july 2015
Member Since: August 27, 2008 Posts: 0 Comments: 1497
000
ABNT20 KNHC 310536
TWOAT
TROPICAL WEATHER OUTLOOK
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
200 AM EDT SAT JUL 31 2010

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

A TROPICAL WAVE LOCATED OVER THE SOUTHEASTERN AND SOUTH-CENTRAL
CARIBBEAN SEA CONTINUES TO PRODUCE DISORGANIZED SHOWERS AND A FEW
THUNDERSTORMS. LITTLE DEVELOPMENT OF THIS SYSTEM IS EXPECTED
UNTIL IT REACHES THE SOUTHWESTERN CARIBBEAN SEA IN A COUPLE OF DAYS.
THERE IS A LOW CHANCE...20 PERCENT...OF THIS SYSTEM BECOMING A
TROPICAL CYCLONE DURING THE NEXT 48 HOURS AS IT MOVES WESTWARD AT
ABOUT 15 MPH.

A LARGE AREA OF DISORGANIZED SHOWERS AND THUNDERSTORMS OVER THE
EASTERN ATLANTIC OCEAN IS ASSOCIATED WITH A TROPICAL WAVE NEAR THE
CAPE VERDE ISLANDS AND A SMALL TROUGH OF LOW PRESSURE LOCATED ABOUT
750 MILES SOUTHWEST 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 CANGIALOSI
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969. xcool
ECMWF 130AM COME
Member Since: September 26, 2009 Posts: 2 Comments: 15672
Quoting KerryInNOLA:
"July 2010
28th-31st. Hot, widely scattered showers, thunderstorms.


August 2010
1st-3rd. Mostly fair.
4th-7th. Showers/thunderstorms, turning mostly fair.
8th-11th. Scattered thunderstorms, then fair.
12th-15th. Pleasant.
16th-19th. Thunderstorms Tennessee east to Carolin"s, then clearing.
20th-23rd. Scattered thunderstorms.
24th-27th. Hurricane threat.
28th-31st. Scattered thunderstorms.


September 2010
1st-3rd. Thunderstorms clear Atlantic Coast, turning pleasant.
4th-7th. Potentially stormy Labor Day weekend, with a hurricane threat.
8th-11th. Pleasant.
12th-15th. Thunderstorms Tennessee east.
16th-19th. Rain showers.
20th-23rd. Mostly fair.
24th-27th. Showery, thunder."

Make fun of them. However, they have been right on target here in NOLA for July28-31. It has been hotter than hell with highs in upper 90s and heat indices greater than 110. They predicted this back in May! Be vigilant for Aug 24-27 and then again over the Labor Day holidays.




Which isn't enough to convince me, and I doubt many others, as well. One correct forecast does not a trustworthy group make. That could easily just have been a coincidence.

Now, if we see repeated results of such accuracy, then maybe I'll change my mind. But until then...
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967. xcool
here come big mommy wave eat 90L
Member Since: September 26, 2009 Posts: 2 Comments: 15672
stalled front off of east fl coast isn't looking too bad- if the shear dies down might need to be watched.

90L still doesn't seem to be getting its act together.

The wave seems alot higher in latitiude than 90L and has a stronger (but more spead out) vorticity then 90L ever had. Wonder what tomorrow will show.
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965. xcool
Member Since: September 26, 2009 Posts: 2 Comments: 15672
964. xcool
:0
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Quoting EricSFL:


LOL had that last night about this time- it wasn't bad considering its fast food tex-mex.
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960. xcool



fish storm cmc


Member Since: September 26, 2009 Posts: 2 Comments: 15672
959. xcool
LOLOL
Member Since: September 26, 2009 Posts: 2 Comments: 15672
Whoever eats that might have to use the restroom immediately afterwards. lol
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957. xcool
90L GETTING better organized
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Quoting will45:


they pretty good for planting a garden tho lol


LOL

true
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Quoting EricSFL:


ahhh come on....now your making me hungry.... :)
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954. xcool
EricSFL .hmmm sound good.
Member Since: September 26, 2009 Posts: 2 Comments: 15672
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952. xcool
EricSFL she need foood like tac bell
Member Since: September 26, 2009 Posts: 2 Comments: 15672
Quoting xcool:



hmmmm


I see the big mommy wave coming off Africa xcool.
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Quoting KerryInNOLA:
You tell me. My grandpa swore by their forecasts. Every time the TV weatherman came on he would throw his little yellow Almanac at the tube and spit and curse!

Gotta be a joke .... the farmer's almanac is nothing more than a climate forecast. And it isn't a very good one at that ... Even a blind bird catches a worm sometimes. Sometime even trolls on here can get lucky and make a prediction like Katrina ..... ;)
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949. xcool
lol
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947. xcool



hmmmm
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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.

This is a joke right?
Member Since: August 27, 2008 Posts: 0 Comments: 1497
Quoting homelesswanderer:


Lol. They predicted 2 major hurricanes on the TX/LA border last September. The first time in years there wasn't a hurricane there. Hmmmm...hope they're predicting another. Lol.


They where off by two months. Ida was a Hurricane in the Gulf in November. Wasn't heading towards TX/LA of course.
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Quoting will45:
Teddy as big as that circle is they may not have to move it


They might as well circle the entire eastern half of the tropical Atlantic.
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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.


Lol. They predicted 2 major hurricanes on the TX/LA border last September. The first time in years there wasn't a hurricane there. Hmmmm...hope they're predicting another. Lol.
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Quoting EricSFL:
Thanks SouthALWX.

Your very welcome :)
Member Since: August 27, 2008 Posts: 0 Comments: 1497
Teddy as big as that circle is they may not have to move it
Member Since: July 18, 2009 Posts: 1 Comments: 994

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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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