African tropical wave 99L has potential to develop

By: Dr. Jeff Masters , 3:10 PM GMT on July 30, 2012

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The first African tropical wave of 2012 with a potential to develop is Invest 99L, located in the Eastern Atlantic near 9°N 36°W, midway between the Lesser Antilles Islands and the coast of Africa. Visible satellite loops show a large area of the surrounding atmosphere has a pronounced counter-clockwise spin, though there is no surface circulation. The disturbance's heavy thunderstorm activity is pretty sparse, but appears to be slowly increasing. Water vapor satellite loops show that 99L has a reasonably moist environment, and the latest Saharan air layer analysis shows that the dry air from the Sahara lies well to the north of 99L. WInd shear over the disturbance is a light 5 - 10 knots, and ocean temperatures are 28°C, (82°F) which is well above the 26.5°C (80°F) threshold typically needed to allow formation of a tropical depression.


Figure 1. Morning satellite image of Invest 99L.

Forecast for 99L
Wind shear is expected to remain light for the next five days, and ocean temperatures will remain near 28°C, according to the 8 am EDT run of the SHIPS model. The disturbance is at 9°N, which is close enough to the Equator that the storm will have some difficultly getting spinning. Most of the models are showing some slow development of 99L, with the storm reaching the Lesser Antilles Islands on Saturday, August 3. NHC gave 99L a 20% chance of developing into a tropical depression by Wednesday morning. I expect the storm will have trouble with dry air at times this week as it crosses the Atlantic, but I give 99L a 50% chance of eventually developing into Tropical Storm Ernesto sometime in the next ten days. Residents and visitors to the Lesser Antilles Islands should anticipate heavy rains and strong winds from 99L beginning to affect the islands as early as Friday night. The long-range fate of 99L is uncertain, but a trough of low pressure is expected to be present over the Eastern U.S. early next week, which would be capable of turning 99L more to the northwest.

Hot in the Central U.S.
The heat in America's heartland continued on Sunday, with Wichita, KS hitting 111°F, just 3° short of their all-time hottest temperature of 114° set on 8/12/1936. Other notable highs on Sunday:

111° Coffeyville, KS
111° Winfield, KS
110° Chanute, KS
110° Parsons, KS
109° Joplin, MO (all-time record is 115° on July 14, 1954)

The low temperature in Tulsa, Oklahoma this Monday morning dropped to only 88°F. This is the all-time warmest low temperature in the city since record keeping began in 1905. The previous record warmest minimum temperature was 87°F set on August 2, 2011 and July 16, 1980. The high in Tulsa Monday - Wednesday is expected to reach 110° - 111°, close to the city's all-time hottest temperature of 115° set on August 10, 1936.

Jeff Masters

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At 2PM:
A. Yellow circle on 99L and NC Blob
B. Yellow circle on 99L
C. Orange circle on 99L
D. Orange circle on 99L and Yellow circle on NC Blob
E. Other

Just give opinions
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Quoting weathermanwannabe:
Thanks Dr. M. Hope someone will start monitoring the Blog a little closer and enforcing any bans on any folks not adhering to the rules or otherwise making inappropriate comments in the very near future. Going into the heart of hurricane season, when lots of folks tune in here for information and informed discussion, is not the place and time for some of the recent activity on the blog.


Well said!
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watchin the tropics
check out my blog page
on wunderground



Link
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Surprise surprise. Another frontal development possible.

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...................................good nhc has a watch out on that blob off the carolina's
Member Since: August 6, 2011 Posts: 4 Comments: 38179
288 hours, yes I know this is fantasy land but look at the wave that came off Africa.
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My take of 99L:
It moves WNW, becomes a 50-60mph storm, and dissipates in the Carribbean.
Or.......
It moves to the NW of the islands and becomes a cat 1 or 2 then follow a track like earls in 2010
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Quoting sunlinepr:
Here comes the BLOB, with his mouth open....

..this one looks better than 99L does, and this one is predicted to cross florida into the gulf come this weekend
Member Since: August 6, 2011 Posts: 4 Comments: 38179
well if its any consolidation, the nogaps is bringing it north of the islands..120 hours out


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................................this offshore Blob sure looks like its gaining rotation
Member Since: August 6, 2011 Posts: 4 Comments: 38179
Here comes the BLOB, with his mouth open....

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Quoting reedzone:


Exactly what I expected since it didn't move north of the islands.
If this pans out it's only hope is for it's remnants to move north to the Bahamas. Also if 99L avoids the Caribbean then it would have no problems.
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Quoting stormchaser19:
..still have to watch that blob off the carolina's
Member Since: August 6, 2011 Posts: 4 Comments: 38179
Quoting wxchaser97:
It is gone at 174 hours and it died in the Caribbean.


Exactly what I expected since it didn't move north of the islands.
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Member Since: August 6, 2011 Posts: 4 Comments: 38179
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Quoting Pocamocca:

Another blogger reedzonemyhero mentioned that to yesterday. Is that another profile you have on here?


This is my one and only account on here.
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Quoting leelee75k:
What's up with the wave near PR and the islands?
Any chance of homegrown development with it?
where is it heading? Florida? Texas?
I would like a rainy weekend if I can have one
..our local weather says that tropical wave is around florida friday,headed into the gulf,just something to watch right now
Member Since: August 6, 2011 Posts: 4 Comments: 38179
It is gone at 174 hours and it died in the Caribbean.
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Quoting KEEPEROFTHEGATE:




Conditions
-2 C 28 F
15.0 knots
227 degrees SW


As of 07/30 14:19


Why post a picture and temperature graph of a place in Greenland on a tropical weather blog? Particularly irrelevant as you don't even tell people what it is. I happen to know that the temperature graph shows the only time since record keeping began there, that the temperature rose above zero C. Still irrelevant, though mildly interesting.
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108 hours from the Nogaps
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Quoting Pocamocca:

Why do you think it dies? What's the cause?


If it heads in the Caribbean, it gets sheared, plus the gradient from the low pressure to the southwest and the high to the north may cause the circulation to retard.
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Storm says that 99L needs to enter the Caribbean to survive and that if it moves north of the islands, wind shear will rip it apart.

Levi says that 99L needs to move north of the islands to survive and that if it moves into the Caribbean, trade winds will rip it apart.

:\
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While "Ernesto" develops looks like a storm develops near Africa...
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Caribbean is unfavorable for development at this time. If 99L is going to be a strong storm then it needs to bypass the Caribbean and go north.
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Conditions
-2 C 28 F
15.0 knots
227 degrees SW


As of 07/30 14:19
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12z Nogaps running now
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Quoting reedzone:
Another scenario is Hurricane Dolly from 2008.. Stayed a tropical wave/disturbance till it reached the Western Caribbean.

If it enters the Caribbean at all it is going to be ripped to shreds. The entire Caribbean is unfavorable and will stay that way for a long time due to very strong trade winds.
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12z GFS still shows development - weaker however.
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XX/INV/99L
MARK
9.85N/35.36W


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Another scenario is Hurricane Dolly from 2008.. Stayed a tropical wave/disturbance till it reached the Western Caribbean.
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no future for 90C?
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What's up with the wave near PR and the islands?
Any chance of homegrown development with it?
where is it heading? Florida? Texas?
I would like a rainy weekend if I can have one
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150 hours
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Quoting Pocamocca:

When do you think it'll become better defined?
It's already getting organized, it's a rather large system, so it will need some time to compact itself and close off a low. I say as early as Wed.
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144 hours
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event detected
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So much for the northerly movement that the GFS was showing, heads it west into the Caribbean. Should kill it off in the next few frames.
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Quoting GTcooliebai:
Two great minds think alike, I was just about to post that. And noticed how in the last run of the GFS it kills it before reaching Haiti and then redevelops it off the southeast coast of FL.
Think Jeanne... Hispaniola ripped it - literally - apart. Then it regenerated N of the Bahamas and hit Abaco, Grand Bahama, and Florida as a cat 3...

David also managed to regenerate to a cat 2? [IIRC] after being mauled by Hispaniola's peaks.

I. E. it's possible for storms to regenerate and come back strong even after crossing Hispaniola or eastern Cuba. Of course this pre-supposes a fairly strong storm to begin with... TSs don't generally fare quite so well.

I guess a lot depends on intensity as it enters the Car, IMO. [Though all of this is moot if it doesn't get into the CAR to begin with...]
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99L looks as if it's in for a tough time. Many have mentioned the shear, dry air, SAL and land interaction that could tear it apart.

However, the same factor that prevented storms from intensifying last year is probably still out there - sinking air. The persistent heat wave and high pressure in the middle of the US probably contributes to sinking air in the tropical Atlantic, and suppresses convection.
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.
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No surface low? That's news to me.

A TROPICAL WAVE ACCOMPANIED BY A SURFACE LOW PRESSURE SYSTEM IS
LOCATED ABOUT 750 MILES SOUTHWEST OF THE CAPE VERDE ISLANDS.
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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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