Two African waves worth mentioning

By: Dr. Jeff Masters , 3:51 PM GMT on July 18, 2009

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There are two African tropical waves worth mentioning today, though neither looks particularly threatening. A tropical wave near 12N 45W, about 1200 miles east of the Lesser Antilles Islands (97 L), is moving west at 15 - 20 mph. This wave is now surrounded by an area of very dry air from the Sahara Desert. The dry air has disrupted most of the wave's heavy thunderstorm activity, and will continue to make it difficult for this system to develop over the next 2 - 3 days. Wind shear is a modest 10 knots over the disturbance, and should remain in the moderate 10 - 15 knot range over the next 2 - 3 days. Thereafter, shear is expected to rise to 20 - 30 knots. This morning's QuikSCAT pass showed no evidence of a surface circulation, and only a modest wind shift associated with 97L. The National Hurricane Center is giving this system a low (less than 30% chance) of developing into a tropical depression in the next 48 hours.

A second tropical wave now approaching the northern Lesser Antilles Islands is under 30 knots of wind shear, and has little prospect of development due to the high shear. However, the wave will bring heavy rain to the islands over the next two days.

None of the computer models are forecasting tropical storm development over the next seven days, and I don't expect either of the two African waves mentioned today to develop over at least the next three days.


Figure 1. Current satellite image of African wave 97L, 1200 miles east of the Lesser Antilles Islands.

I'll have an update Sunday afternoon.
Jeff Masters

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Where's the quikscat when you need it.
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Thats quite the Linguistic superlative.

Fascinating insight.



Central Atlantic - Visible Loop
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Quoting RufusBaker:
If ya ask ole Rufus Ide have to say that these waves arent worth a good ole country dump.


stop being weird lol
297. 7544
moisture from 97l is now training into the blob we may have something going on pretty soon stay tuned
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the shear at the right angle can make it look like a low is forming, when it really isnt

I am out for a while, gotta run some errands...
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Quoting hunkerdown:
Do not go by the radar to determine a "forming" low.
really, why?
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Quoting BurnedAfterPosting:


After looking I agree with you


I 3rdly agree, it's getting sheared, why would they tag it? Maybe if the models are right, later on this will be an interesting feature. For now.. hmmm :/
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Quoting Patrap:
Geez,..never seen so many different opines on one page before.



Hehe...
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Quoting Patrap:
Geez,..never seen so many different opines on one page before.



my psychic powers tell me...
another explosion today similar to yesterdays..
and tomorrow..
and monday.......

sigh
Member Since: July 7, 2008 Posts: 2 Comments: 3237
Quoting canesrule1:
are you blind? the is a low right there look at it.
Do not go by the radar to determine a "forming" low.
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Water Vapor (IR3)

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Geez,..never seen so many different opines on one page before.

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Quoting chsweatherintern2009:
weather channel said nothing will happen with the blob
don't listen to the TWC listen to the NHC.
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Quoting chsweatherintern2009:
weather channel said nothing will happen with the blob


they always say that. but they're probably right with the wave next to the lesser antilles.
Member Since: July 7, 2008 Posts: 2 Comments: 3237
Quoting wsvnweatherteam:
ha thats funny
Please tell me your name is not indicative of your job.
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Quoting BurnedAfterPosting:


After looking I agree with you
really there is a low there, im about 80+% sure.
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weather channel said nothing will happen with the blob
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Quoting hunkerdown:
Sorry, don't see a low forming nor do I see this as being an invest in the very near future. Also, winds accompanied in tstorms/rain/showers are not actual as they are deemed "rain caused".
are you blind? the is a low right there look at it.
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Quoting hunkerdown:
Sorry, don't see a low forming nor do I see this as being an invest in the very near future. Also, winds accompanied in tstorms/rain/showers are not actual as they are deemed "rain caused".


After looking I agree with you
invest 98L by later today wouldnt be a surprise at all.. however this wave will probably be too north to stay in the caribbean for long and will probably move WITH the shear to the bahamas and still get sheared. i still think 97L has a better chance.
Member Since: July 7, 2008 Posts: 2 Comments: 3237
watch the blob I'm thinking Invest before 5.
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Quoting SLU:
Link

look at the tight swirl developing just east of Guadeloupe. Definitely a low forming. It's going to be an invest pretty soon. The convection on the eastern side is very strong. Antigua reported winds to 28mph in heavy showers a couple hours ago.
Sorry, don't see a low forming nor do I see this as being an invest in the very near future. Also, winds accompanied in tstorms/rain/showers are not actual as they are deemed "rain caused".
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T9 has been raised...

---
The Increasing Gale or Storm Signal, No. 9, was issued at
1:30 a.m.

This means that winds are expected to increase
significantly.

Molave will be very close to Hong Kong in the next few
hours. Gale force winds are generally affecting Hong Kong.
Winds will strengthen further with heavy rain and squalls.
According to the present track, local winds will turn
southwesterly before daybreak. Places previously sheltered
from the winds will become exposed. Members of the public
should take precautions as soon as possible.
In the past hour, the maximum sustained winds recorded at
Tap Mun and Lau Fau Shan were 96 and 84 kilometres per hour
with maximum gusts 148 and 104 kilometres per hour
respectively.
A high water level of 2.9 metres above chart datum is
expected at Quarry Bay between 4:00 a.m. and 7:00 a.m. The
high water level may cause flooding in low-lying areas in
Sheung Wan.
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Quoting SLU:
Link

look at the tight swirl developing just east of Guadeloupe. Definitely a low forming. It's going to be an invest pretty soon. The convection on the eastern side is very strong. Antigua reported winds to 28mph in heavy showers a couple hours ago.
Holy shoot, we got a low, we will have an invest very soon, thanks for that!!
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272. 7544
Quoting SLU:
Link

look at the tight swirl developing just east of Guadeloupe. Definitely a low forming. It's going to be an invest pretty soon. The convection on the eastern side is very strong. Antigua reported winds to 28mph in heavy showers a couple hours ago.


possible 98l soon if it all hold together imo it will
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Quoting SLU:
Link

look at the tight swirl developing just east of Guadeloupe. Definitely a low forming. It's going to be an invest pretty soon. The convection on the eastern side is very strong. Antigua reported winds to 28mph in heavy showers a couple hours ago.


well if a low forms than that is a different story
Quoting BurnedAfterPosting:
did you guys actually read the TWO?

It tells you right away why the convection flared up, Keeper showed everyone that convection is waning fast
They can't type that fast at the NHC.
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269. SLU
Link

look at the tight swirl developing just east of Guadeloupe. Definitely a low forming. It's going to be an invest pretty soon. The convection on the eastern side is very strong. Antigua reported winds to 28mph in heavy showers a couple hours ago.
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Quoting BurnedAfterPosting:
did you guys actually read the TWO?

It tells you right away why the convection flared up, Keeper showed everyone that convection is waning fast
yeah, now keeper is examining it, for all you guys that don't see what we mean by fading, just look at the sides 3 hours ago you could see on the satellite the dark reds on the sides now its a light green and yellow, convection is definitely waning fast.
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Quoting WxLogic:


Currently all 3 models... GFS, CMC, and NOGAPS forecasting shear to lift out... with NOGAPS being the most aggressive and more conductive for development.

Of course this will all remain to be seen as shear tends to be more trickier to forecast as it might not always behave the way you would expect.
What the models are forcasting at is the steering and POSSIBLE development and path of such "development". The shear is a component that would aid/hamper the POSIBLE development of such systems. Keep on mind there are only computer models that can be fickle and tempermental when dealing with a "system" that is not truly in place.
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ha thats funny
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did you guys actually read the TWO?

It tells you right away why the convection flared up, Keeper showed everyone that convection is waning fast
Quoting 7544:
if the blob still looks like this at 8 pm we will have something to watch
agreed
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263. 7544
if the blob still looks like this at 8 pm we will have something to watch
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Quoting Seflhurricane:
so it now appears computer models are projecting that the tropical wave near 60W has a chance to develop when shear relaxes somewhat


Currently all 3 models... GFS, CMC, and NOGAPS forecasting shear to lift out... with NOGAPS being the most aggressive and more conductive for development.

Of course this will all remain to be seen as shear tends to be more trickier to forecast as it might not always behave the way you would expect.
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Quoting CybrTeddy:
They changed their tune slightly for the other wave off the Islands. They said Upper Level winds were't favorable for development at 8, at 2 PM they said not favorable for significant development.


Noticed that Cybr, what will they say at 8 pm is the question....assuming the wave is still looking like it is now.
Member Since: June 29, 2009 Posts: 13 Comments: 5315
Quoting hunkerdown:
Did you ever see a hair split ?


LMAO
12Z UKMET seems to hinting a similar scenario.
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Quoting CybrTeddy:
They changed their tune slightly for the other wave off the Islands. They said Upper Level winds were't favorable for development at 8, at 2 PM they said not favorable for significant development.
Did you ever see a hair split ?
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They changed their tune slightly for the other wave off the Islands. They said Upper Level winds were't favorable for development at 8, at 2 PM they said not favorable for significant development.
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Quoting futuremet:


This could lead to an outbreak of development, because there are other waves that are following this system. A vigorous tropical wave is about to emerge off the African coast.



These 2 ways helped moisten up the E and C Atlantic regions so far even during a negative MJO face. So can't imagine what could happen during the positive phase that will be approaching towards the end of this month into August.

New ways should have an easier time keeping their convection(s) longer in the upcoming weeks.
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still two yellows on the TWO
Link
Member Since: June 13, 2009 Posts: 2 Comments: 12719
254. 7544
Quoting Orcasystems:


ROFL, its just my S&I acting up....


its all good lol
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Blog Update
Reflector site for those at work, which includes Weather456, daily updates


AOI

AOI

AOI
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Another healthy wave emerging. Maybe another AOI?

Member Since: June 29, 2009 Posts: 13 Comments: 5315
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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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