Little change to 90L; new African tropical wave is worth watching
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
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Seems as if the surface trough is catching back up to the wave to it's west. Allstar's assessment is a reasonable one. That would be the best shot is for the surface trough to regen the surface low.
Looks about right to me.
Well, I can see a sfc. low forming where you said. It does appear the spin is getting better defined.
I dont see it
I think it is SLOWLY getting better organized / re-organizing.
All that orange reminds me...3 months til Halloween!
Yes, but it is very broad. It needs to tighten and organize before we get too concerned about a tropical cyclone forming.
YUP, the spin is pretty obvious on visible satellite - and also getting more organized with convection - I see something forming here!!
you're a bald gray guy??
As a side-note, I wouldn't be surprised to see the tropical wave in between 35W-40W get tagged an invest later this evening.
Isn't that what we are talking about?
AOI
AOI
AOI
AOI
AOI
TS BUSTED FORECAST ALIBI
It will be shown here that for storms originating in tropical waves, the synoptic wave itself plays a vital role in the near-surface circulation. In our proposed tropical-wave scenario the relevant theoretical paradigm is the formation of a closed proto-vortex within the wave in the lower troposphere and subsequent eddy shedding whereby the vortex, energized further by deep convective heating, becomes detached from the wave and begins to control its own destiny. In what follows we refer to this sequence of events as the marsupial paradigm.
Our series on TC genesis, of which this paper is the first, addresses the tropical wave pathway and variations thereof (easterly wave propagation, tropical depression disturbances, instability of the ITCZ, and trapped equatorial modes) and the ability of these disturbances to create a closed gyre or “pouch” and subsequently within the pouch, a proto-vortex or “embryo” favorable for hurricane formation.
What the heck is a trapped equatorial mode?
It is probably in the que to be approved first.
Yes yes yes.. what did I do :(
Hmmmm, downdrafts apparently are an important positive component in TC genesis--besides the negative signal given by arc clouds. In reviewing prior research the authors comment:
The rotational confinement of these gust front boundaries appears important for sustained deep convective activity within the MCV embryo and surface spin-up. Even when gravity waves and gust fronts are not fully contained, they can be expected to play an important role in convective triggering along developing vortical boundaries in the proto-storm.
Haven't heard about vortical hot towers from people on the blog. Cool stuff.
That's what I am seeing on RGB imagery as well. Looks like a broad area of low pressure. Convection is flowing cyclonic towards the surface trough axis. It still appears that the two disturbances have yet to phase.
A.10-14 storms
B.14-18 storms
C.18-22 storms
D. Over 22 name storms
What comes before A?
B - C
B.
Hey.. I just want to know what people think so far..
Thats my plan... keep them guessing :)
You think this season is going to be a bust?
Wow! I actually am seeing it right!
Ahhhhh now there is the first problem in your theory. Your making the assumption that all of the people on here think. We know from many previous experiences, that is not necessarily true :)
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