African Tropical Wave 98L Moving Over Cooler Waters

By: Dr. Jeff Masters , 2:23 PM GMT on July 23, 2013

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A strong and well-organized tropical wave that moved off the coast of Africa on Monday (98L) is located a few hundred miles south of the Cape Verde Islands and is moving west-northwest at 15 - 20 mph. Satellite images show that 98L has a decent amount of spin, but only a modest amount of heavy thunderstorms that have not changed much in intensity or areal coverage this morning. The wave is under a moderate 10 - 20 knots of wind shear, which will tend to allow slow development. A large amount of dry air lies to the north and west of 98L, and this dry air will likely interfere with development later this week. The SHIPS model predicts that wind shear will stay in the moderate range through Saturday. Ocean temperatures are barely adequate for development, about 26.5°C today, and will be below average over the region of ocean 98L will be traversing on Wednesday and Thursday, 25 - 26°C. These temperatures are very marginal for development. The Madden Julian Oscillation (MJO), a pattern of increased thunderstorm activity near the Equator that moves around the globe in 30 - 60 days, does not favor increased chances of Atlantic tropical cyclone formation this week. The reliable computer models for tropical cyclone genesis do not predict that 98L will develop this week. In their 8 am EDT Tuesday Tropical Weather Outlook, NHC gave 98L a 40% chance of developing into a tropical cyclone by Thursday. 98L should maintain a west-northwest track through the week, and may spread heavy rains and gusty winds to the northern Lesser Antilles Islands beginning on Saturday night or on Sunday.


Figure 1. Satellite image of 98L off the coast of Africa taken at 8 am EDT Tuesday July 23, 2013, with a satellite analysis of where dry air is, as well. A large amount of dry air lies to the north and west of 98L, and will likely interfere with development later this week. Image credit: University of Wisconsin CIMSS and NOAA/HRD.

Jeff Masters

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2228. pcola57
Quoting 2225. PensacolaDoug:
Dorian at 11AM I do believe. (I have been wrong before however)


Morning Doug..
Did you get any of that weather that moved through last eve..
I lost some foilage..
Weird wind..
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Quoting 2222. pcola57:


LOl Lol..
Morning Washi.. :)
Stranger things have happened..
It's OK.. :)
Yeah your right.lol.
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Quoting 2179. pcola57:
Good Morning All..

ESA launch from French Guiana, Africa tomorrow..
The link is below..
By the way..
If anyone is good at time conversion on this launch
Would be great if you would post it..
Thanks..

Join us live on 25 July, 2013, to watch Alphasat, Europes largest and most sophisticated telecommunications satellite, launch into its planned orbit from Kourou, French Guiana. Streaming starts 15 minutes before lift-off, with the launch window between 19:53 GMT (21:53 CEST) and 21:11 GMT (23:11 CEST).


I see we now have TD4..
And by the posts I've read so far..
NHC wants to bring it up to climo position of the past for it's duration..
I have problems with climo this year as since last year..
Hate to bring it up but Sandy, Winter storms,East to West flow,Chantal all give me a sense of very irregular Jet/Sub Jet/ flowpattern set up for the Northern Hemisphere..
As always go with the experts..
As this is Just My Observations and Opinion.. :)
That's between 3:53 PM EDT and 5:11 PM EDT on the 25th.
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Dorian at 11AM I do believe. (I have been wrong before however)
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2224. Grothar
Quoting 2188. K8eCane:



we will have to type lone ranger theme speed to keep up with the blog


First smile of the day :)
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Quoting 2213. HurricaneAndre:
Tropical Storm Dorian is born.


Hey thanks to your images we were able to see Dorian before the files updated. And still could strengthen a little later today.
Member Since: May 25, 2012 Posts: 0 Comments: 2043
2222. pcola57
Quoting 2217. washingtonian115:
No how could this happen


LOl Lol..
Morning Washi.. :)
Stranger things have happened..
It's OK.. :)
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TS Dorian is here with us, stronger already than Chantal ever was if I'm not mistaken with 1006mb pressure.
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04L has gotten to look much better than I would though mainly because of the small size allow it to deepen a little more but dont let the size fool you it has an excellent moisture pulling moisture from it south and east.
Member Since: May 25, 2012 Posts: 0 Comments: 2043
2219. Levi32
34 minutes before the satellite image revealing the "eye," this AMSU pass revealed no eye.



Member Since: November 24, 2005 Posts: 635 Comments: 26652
Quoting 2209. Levi32:
Although this does look like an eye, it's premature to call it one until we get a more recent microwave pass. It could very well be a pinch of dry air that got into the center. With a super compact system like this, it would not be surprising to see some nice core structure, but that doesn't mean it's a hurricane.



Interesting to say the least.
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Quoting 2212. Thing342:
AL, 04, 2013072412, , BEST, 0, 140N, 290W, 35, 1006, TS, 34, NEQ, 30, 0, 0, 30, 1012, 150, 20, 0, 0, L, 0, , 0, 0, DORIAN, D,
No how could this happen
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2216. Kyon5

Quoting 2212. Thing342:
AL, 04, 2013072412, , BEST, 0, 140N, 290W, 35, 1006, TS, 34, NEQ, 30, 0, 0, 30, 1012, 150, 20, 0, 0, L, 0, , 0, 0, DORIAN, D,
LOL, I was just about to put it.
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AL, 04, 2013072412, , BEST, 0, 140N, 290W, 35, 1006, TS, 34, NEQ, 30, 0, 0, 30, 1012, 150, 20, 0, 0, L, 0, , 0, 0, DORIAN, D,
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I have been noticing on my tropical cyclone weather pages I look at that an area of strengthening 850mb vorticity is developing over SC and GA this morning and is beginning to emerge into the Atlantic Ocean. This area of 850mb vorticity could enhance low level winds and develop a circulation at the surface, its already a rotating area of clouds over SC and GA and wont take much convection to get this system tropical, it needs to detach from the cold front off the east coast first before it becomes tropical. SSTs are high, but wind shear is a little strong currently and is increasing over our disturbance, time will tell whether SNE sees a tropical cyclone or nor'easter.
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Tropical Storm Dorian is born.
Member Since: June 11, 2013 Posts: 20 Comments: 3212
AL, 04, 2013072412, , BEST, 0, 140N, 290W, 35, 1006, TS, 34, NEQ, 30, 0, 0, 30, 1012, 150, 20, 0, 0, L, 0, , 0, 0, DORIAN, D,
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Good morning everybody. Would not be at all surprised to see the models sift even farther south today.
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Quoting 2197. superpete:
A good view here of the next wave behind TD 4 to emerge off West Africa. Could be a bit further south than I-98 was. Good morning all!

Norwegian Met Inst' /Eumetsat

Link


04L has eradicate SAL for any tropical wave that wants to roll off Africa to develop with more ease. In terms of 04L I thankful there is cooler sst temps or this would look to be another IKE look a like.
Member Since: May 25, 2012 Posts: 0 Comments: 2043
2209. Levi32
Although this does look like an eye, it's premature to call it one until we get a more recent microwave pass. It could very well be a pinch of dry air that got into the center. With a super compact system like this, it would not be surprising to see some nice core structure, but that doesn't mean it's a hurricane.

Member Since: November 24, 2005 Posts: 635 Comments: 26652
2208. pcola57
Quoting 2200. RTLSNK:


1953 is military time for 7:53 PM
GMT time is 4 hours ahead of Eastern Time
So 1953 GMT would be 3:53 PM Florida Time

I think thats correct, someone else check it please.:)


Thanks a ton Snake.. :)
And VR46L..
Good Morning.. :)
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2207. VR46L
Quoting 2200. RTLSNK:


1953 is military time for 7:53 PM
GMT time is 4 hours ahead of Eastern Time
So 1953 GMT would be 3:53 PM Florida Time

I think thats correct, someone else check it please.:)


It is currently 12.30 GMT if thats any help ..as I am in BST At the moment which is one hr ahead
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Member Since: May 23, 2012 Posts: 0 Comments: 4666
2205. jeebsa
Hebert Boxes are named for former National Weather Service and National Hurricane Center forecaster Paul Hebert, who observed in the late 1970's that most strong hurricanes (characterized as those with winds exceeding 110 miles per hour (177 km/h)) which had struck South Florida since 1900 had also passed through one of these two small 335-mile-by-335-mile (517-km-by-517-km) square geographic regions.
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Quoting 2184. HurricaneAndre:


I see 35 kt winds this is the next best thing to recon so upgrade likely and probably more strengthening is plausible before it hit really cooler sst this evening.
Member Since: May 25, 2012 Posts: 0 Comments: 2043
2203. SLU
If the shear is low when it gets to 50 west, it could strengthen much more than 45mph.

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Quoting 2187. Grothar:


Don't start yet. :)


But cant you see? PINHOLE! :D
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As so many on here have noted recently, the most concerning part of this current depression is the strong ridging at the moment.......It could cause a real powerful Cape Verde storm in the August-Sept period to threaten the Caribbean and beyond. Even at storm status, future Dorian still expected to head west with no recurvature as it heads towards the Bahamas at the end of the current period......Not a good sign for the remainder of the season.
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2200. RTLSNK
Quoting 2179. pcola57:
Good Morning All..

ESA launch from French Guiana, Africa tomorrow..
The link is below..
By the way..
If anyone is good at time conversion on this launch
Would be great if you would post it..
Thanks..

Join us live on 25 July, 2013, to watch Alphasat, Europes largest and most sophisticated telecommunications satellite, launch into its planned orbit from Kourou, French Guiana. Streaming starts 15 minutes before lift-off, with the launch window between 19:53 GMT (21:53 CEST) and 21:11 GMT (23:11 CEST).


I see we now have TD4..
And by the posts I've read so far..
NHC wants to bring it up to climo position of the past for it's duration..
I have problems with climo this year as since last year..
Hate to bring it up but Sandy, Winter storms,East to West flow,Chantal all give me a sense of very irregular Jet/Sub Jet/ flowpattern set up for the Northern Hemisphere..
As always go with the experts..
As this is Just My Observations and Opinion.. :)


1953 is military time for 7:53 PM
GMT time is 4 hours ahead of Eastern Time
So 1953 GMT would be 3:53 PM Florida Time

I think thats correct, someone else check it please.:)
Member Since: Posts: Comments:
Quoting 2158. GatorWX:
"And through the window in the wall
comes streaming in on sunlight wings
A million bright ambassadors of morning"



Have a great day everyone!


Clear spot in the convection...is that the center?
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Quoting 2183. weathermanwannabe:
Good Morning. Gives us something to talk about. A tropical storm in Hebert Box 1 on Monday.......
Yes, I just checked the coordinates of the definition of Hebert Box 1 = 15-20N and 60-65W or 335 miles by 335 miles. Oh boy.
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A good view here of the next wave behind TD 4 to emerge off West Africa. Could be a bit further south than I-98 was. Good morning all!

Norwegian Met Inst' /Eumetsat

Link
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Has anyone noticed that the box around TD 4 on the NHC website is green? Or is it just me?
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Quoting 2194. pcola57:


Keep up the good work.. :)
you too.Thanks.
Member Since: June 11, 2013 Posts: 20 Comments: 3212
2194. pcola57
Quoting 2191. HurricaneAndre:
morning pcola.


Keep up the good work.. :)
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Quoting 2188. K8eCane:



we will have to type lone ranger theme speed to keep up with the blog


Yup. Best time to blog during a threatening storm is between midnight and 8:00 am when the traffic is a little slower before everyone logs on at work..... :)
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Quoting 2176. LargoFl:
is that an eye trying to form?...........

that you see is the Northern Band tightening up the LLCOC is actually just under where you see that red spot its about 13.4N 28.6W moving W bound at about 275/280 degrees
Member Since: June 13, 2009 Posts: 2 Comments: 12140
Quoting 2189. pcola57:


Morning Andre..
Nice ascending pass..
Would like to compare that with a current descending pass when available..
morning pcola.
Member Since: June 11, 2013 Posts: 20 Comments: 3212
Member Since: May 23, 2012 Posts: 0 Comments: 4666
2189. pcola57
Quoting 2184. HurricaneAndre:


Morning Andre..
Nice ascending pass..
Would like to compare that with a current descending pass when available..
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2188. K8eCane
Quoting 2183. weathermanwannabe:
Good Morning. Gives us something to talk about. A tropical storm in Hebert Box 1 on Monday.......



we will have to type lone ranger theme speed to keep up with the blog
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2187. Grothar
Quoting 2176. LargoFl:
is that an eye trying to form?...........


Don't start yet. :)
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2186. Grothar
Quoting 2177. Hurricanes305:

Hey Gro, the long nights are ahead of us. Good old hurricane season.But that slight WNW track north of the islands is very interesting as there is a forecast for a big 600 DM High in the next couple of day that is capable of sending a deepening low very close to SE US (Florida up to the Carolinas). just speculating as that is far out still :)


But they have been pretty good with these forecast from the beginning. All models predicted a WNW motion and that it what is has been doing. The high is expected to build back in a few days, so it will be interesting to see how much influence it will have on it.
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This pattern is very favorable as the TUTT north of 04L will ventilate our system on the northern side and help deepen it. 



Member Since: May 25, 2012 Posts: 0 Comments: 2043
Member Since: June 11, 2013 Posts: 20 Comments: 3212
Good Morning. Gives us something to talk about. A tropical storm in Hebert Box 1 on Monday.......
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2181. LargoFl
Check out Africa behind dorian.........................
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Member Since: June 11, 2013 Posts: 20 Comments: 3212
2179. pcola57
Good Morning All..

ESA launch from French Guiana, Africa tomorrow..
The link is below..
By the way..
If anyone is good at time conversion on this launch
Would be great if you would post it..
Thanks..

Join us live on 25 July, 2013, to watch Alphasat, Europes largest and most sophisticated telecommunications satellite, launch into its planned orbit from Kourou, French Guiana. Streaming starts 15 minutes before lift-off, with the launch window between 19:53 GMT (21:53 CEST) and 21:11 GMT (23:11 CEST).


I see we now have TD4..
And by the posts I've read so far..
NHC wants to bring it up to climo position of the past for it's duration..
I have problems with climo this year as since last year..
Hate to bring it up but Sandy, Winter storms,East to West flow,Chantal all give me a sense of very irregular Jet/Sub Jet/ flowpattern set up for the Northern Hemisphere..
As always go with the experts..
As this is Just My Observations and Opinion.. :)
Member Since: Posts: Comments:
Quoting 2176. LargoFl:
is that an eye trying to form?...........


Lol it's just wrapping up a bit

Gotta love it though!
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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.