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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The swirl several hundred miles northeast of Puerto Rico and a few hundred miles due east of Bermuda:

BEGIN
NHC_ATCF
invest_al992013.invest
FSTDA
R
U
040
010
0000
201307241525
NONE
NOTIFY=ATRP
END
INVEST, AL, L, , , , , 99, 2013, DB, O, 2013072412, 9999999999, , , , , , METWATCH, , AL992013
AL, 99, 2013072412, , BEST, 0, 304N, 556W, 20, 0, DB, 0, , 0, 0, 0, 0,
Member Since: Posts: Comments:
Quoting 2771. Methurricanes:
When is the east coast storm suppose to pull together, tomorrow afternoon?


Sometime tomorrow afternoon
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2776. KEEPEROFTHEGATE (Mod)
04L/TS/D/CX
Member Since: July 15, 2006 Posts: 169 Comments: 53296
2775. Grothar
Quoting 2769. GTstormChaserCaleb:
Yes I can't remember if it was the GFS or CMC showing it, but now both models show it. Remember I asked you if you thought there was a chance for a trough split around the same time we had Dorian approaching the islands?


I remember everything Caleb. :)

I even kept my hurricane tracking map from '92. Primitive but useful.

Member Since: July 17, 2009 Posts: 69 Comments: 25369
Quoting 2741. whitewabit:


you would have to understand .. in 1992 at 600 mile out they did not know where it was going !! so saying our neighborhood is not far off ..


I remember tracking Hurricane Allen in 1980 with the charts you would get free at gas stations and stores. Each day you listened to the news and marked the new location of the hurricane. I lived in Raymondville, TX at that time.
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The "eye like" feature might be a dry air. Also, this storm is TINY. Many people struggles with a small storms, as they could strengthen faster than expected.
Member Since: August 1, 2011 Posts: 28 Comments: 7903
When is the east coast storm suppose to pull together, tomorrow afternoon?
Member Since: Posts: Comments:
ok new images are in and I see Dorian located 14.2N 29.9/30.0W and that "mid level eye" seem to spun around making it complete however the thunderstorm tht was with it are dying as a result not only that the "Mid Level Eye" and the LLCOC have become rather elongated WNW-ESE it may be so that it has had a jolt of intensification but jolted back down now its wait and watch at this point
Member Since: June 13, 2009 Posts: 2 Comments: 11033
Quoting 2759. Grothar:


Is that the one you were showing the other night?
Yes I can't remember if it was the GFS or CMC showing it, but now both models show it. Remember I asked you if you thought there was a chance for a trough split around the same time we had Dorian approaching the islands?
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Just a wrong day to have 8 hours shift at work... oh well. I should have another blog up either tonight after 11 pm or the first thing tomorrow around 12 or 1 pm.
Member Since: August 1, 2011 Posts: 28 Comments: 7903
Quoting 2758. AussieStorm:


yeah,,, And Dorian is male, not female.


Whoops! Thanks for the correction!
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Quoting 2748. Patrap:


The actual energy for that possible scenario is now here ironically.





Actually that energy is for the second nor'easter forecasted to develop this weekend near the Bahamas. A mid level low over GA is responsible for the nor'easter this week hitting SNE.
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Quoting 2748. Patrap:


The actual energy for that possible scenario is now here ironically.





Yea, there are several "pivots" involved here. The first one is just headed off the SE coast of GA. The second vort max is over southern AL and the last piece is the one you showed in OK. We are going to get a rare summertime negatively tilted trough here in the eastern US. This is going to be a decent storm, maybe sub-tropical or something along those lines. Cape Hatteras north will be impacted by this storm from Friday and into the weekend.
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Quoting 2748. Patrap:


The actual energy for that possible scenario is now here ironically.





Actually that could be a different one that develops off the FL coast on Friday...I think I saw an MCS coming the other way a few yrs ago; rounding a mid Continent ridge then going offshore near the NJ coast and sliding down the gulf stream and then into the Gomex. It was odd.
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The last time we had two named systems East of the Islands in July was Dennis and Emily of 2005. Very rare but could be indicative of a busy Cape Verde season.
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2762. VR46L
Quoting 2740. Chucktown:


That is going to be a formidable storm this weekend. Watch for a strong Nor'easter possibly transitioning to a tropical entity as it heads up the east coast. This bears more watching than Dorian I believe.

Link


Oh My !!

Dorian , Subtropical entity and the wave in Africa will be hitting the water in a couple of Days .... Its all kicking off now EEK !
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Quoting 2672. LargoFl:
Dorian is coming into view now


Wow it has a buzz saw look to it as it continues to tighten up its circulation this may go to 60 mph by 5pm. But will be able to maintain that level of intensity for the next 36 hours but after that models predicting low shear as the TUTT moves north and ventilate our system it could easily intensify once again.
Member Since: May 25, 2012 Posts: 0 Comments: 2043
It's already at 50 mph, I would say hurricane , maybe at 5 or 11 pm tonight, just my guess ! And as far as any recurve , it depends on what , if anything that one of the maps , shows off the east coast ! That will be the only weakness , to that massive Bermuda high !
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2759. Grothar
Quoting 2753. GTstormChaserCaleb:
ncstorm has been saying that for days and I have been watching the models too show this area.


Is that the one you were showing the other night?
Member Since: July 17, 2009 Posts: 69 Comments: 25369
Quoting tropicfreak:


Kind of unusual knowing that it already surpassed the 5 am forecast peak intensity of 45 mph. It is already a 50 mph storm. I have a feeling that Dorian might have a few more tricks up her sleeve.


yeah,,, And Dorian is male, not female.
Member Since: September 30, 2007 Posts: 9 Comments: 15932
2757. Times2
Quoting 2713. AussieStorm:
Is the NHC saying Dorian is as good as he's going to get?



Traveling at 21mph.


Actually doing what they always do, forecasting. Unfortunatley they are not great at it 120 hours out. Dorian is small so it may not intensify much or lose much going thru that patch of cool water and some dry air. Next week around Monday will be very interesting.
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Quoting 2747. Progster:
Canadian GEM hi res develops a weak STS off the NJ coast by Friday morning. I've seen this happen before with similar set-ups. Lots "o" instability and from time to time the convective feedback is real.

Link


NAM shows something similar, except it develops off the NC/VA coast.
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12z GFS Int:

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2754. Dakster
Quoting 2752. weathermanwannabe:


Which would normally signal a fish storm but the ridging is not cooperating this time......



Ugh... Yes. The B-High is being non-cooperative for that type of setup. But as they say, timing is everything.
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Quoting 2747. Progster:
Canadian GEM hi res develops a weak STS off the NJ coast by Friday morning. I've seen this happen before with similar set-ups. Lots "o" instability and from time to time the convective feedback is real.

Link
ncstorm has been saying that for days and I have been watching the models too show this area.
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Quoting 2745. SLU:
OF NOTE:

Operationally speaking, the formation of TS Dorian at 29.9W makes it the 4th furthest east that a TS has ever formed in the Atlantic before August 1st. The most recent one being MH Bertha.



Which would normally signal a potential fish storm but the ridging is not cooperating this time......
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Quoting 2741. whitewabit:


you would have to understand .. in 1992 at 600 mile out they did not know where it was going !! so saying our neighborhood is not far off ..

Yeah, well we all know that they were more, shall we say, Calm, Cool, and Collected about storms back then. That is the point I'm trying to make.
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Quoting 2735. CybrTeddy:
Just remember how difficult it is to predict intensity for tropical cyclones, especially ones as small as Dorian. Here's the first advisory forecast for Major Hurricane Michael last year.

INIT 03/2100Z 25.6N 42.2W 30 KT 35 MPH
12H 04/0600Z 25.8N 42.9W 35 KT 40 MPH
24H 04/1800Z 26.4N 43.7W 35 KT 40 MPH
36H 05/0600Z 27.3N 44.3W 35 KT 40 MPH
48H 05/1800Z 28.0N 44.5W 30 KT 35 MPH
72H 06/1800Z 28.5N 44.5W 25 KT 30 MPH...POST-TROP/REMNT LOW
96H 07/1800Z 29.5N 44.5W 20 KT 25 MPH...POST-TROP/REMNT LOW
120H 08/1800Z 30.5N 44.5W 20 KT 25 MPH...POST-TROP/REMNT LOW

Intensity forecasts are always the most difficult to forecast, when you have the usually reliable LGEM peaking at near Cat 2 in 5 days it bears close watching.
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Quoting 2589. whitewabit:


Aren't they releasing large amounts of water into both rivers out of "O"
Big time, this would be terrible for the lake and all of the estuaries they are dumping into.
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2748. Patrap
Quoting 2740. Chucktown:


That is going to be a formidable storm this weekend. Watch for a strong Nor'easter possibly transitioning to a tropical entity as it heads up the east coast. This bears more watching than Dorian I believe.

Link


The actual energy for that possible scenario is now here ironically.



Member Since: July 3, 2005 Posts: 421 Comments: 127566
Canadian GEM hi res develops a weak STS off the NJ coast by Friday morning. I've seen this happen before with similar set-ups. Lots "o" instability and from time to time the convective feedback is real.

Link
Member Since: Posts: Comments:
2746. Dakster
Quoting 2740. Chucktown:


That is going to be a formidable storm this weekend. Watch for a strong Nor'easter possibly transitioning to a tropical entity as it heads up the east coast. This bears more watching than Dorian I believe.

Link


Yuck... I guess so.
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2745. SLU
OF NOTE:

Operationally speaking, the formation of TS Dorian at 29.9W makes it the 4th furthest east that a TS has ever formed in the Atlantic before August 1st since 1851. The most recent one being MH Bertha 2008.

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purely talking track. not intensity or timeline just track
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Quoting 2735. CybrTeddy:
Just remember how difficult it is to predict intensity for tropical cyclones, especially ones as small as Dorian. Here's the first advisory forecast for Major Hurricane Michael last year.

INIT 03/2100Z 25.6N 42.2W 30 KT 35 MPH
12H 04/0600Z 25.8N 42.9W 35 KT 40 MPH
24H 04/1800Z 26.4N 43.7W 35 KT 40 MPH
36H 05/0600Z 27.3N 44.3W 35 KT 40 MPH
48H 05/1800Z 28.0N 44.5W 30 KT 35 MPH
72H 06/1800Z 28.5N 44.5W 25 KT 30 MPH...POST-TROP/REMNT LOW
96H 07/1800Z 29.5N 44.5W 20 KT 25 MPH...POST-TROP/REMNT LOW
120H 08/1800Z 30.5N 44.5W 20 KT 25 MPH...POST-TROP/REMNT LOW
Yeah we all know how that turned out..
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With the Microwave pass from earlier showing a forming eye wall and this statement made by Stewart, "MAXIMUM SUSTAINED WINDS ARE NEAR 50 MPH...85 KM/H...WITH HIGHER
GUSTS. SOME SLIGHT STRENGTHENING IS POSSIBLE TODAY" there is a chance we could have our first hurricane of the season if current trends in organization continue.
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2741. whitewabit (Mod)
Quoting 2724. opal92nwf:
(I moved this comment)

Wow, oh my goodness...The opening of the segment on the Weather Channel is BREAKING NEWS 4th Storm of the Season Tropical Storm Dorian will it threaten the US?

Now I am not dissing them for thinking it could eventually impact the US and for advertising that, but this is such a contrast to how people treated storms in years past such as hurricane Andrew in 1992. Watch how they actually don't say out loud that Andrew could hit South Florida in this clip. Even when it is 615 miles from Miami and heading due West, he uses general terms like "it will be in our neighborhood"...Amazing how times have changed. It's just a simple media technique to get people latched on to a storm thousands of miles away so that they will watch that television station.
img src="">


you would have to understand .. in 1992 at 600 mile out they did not know where it was going !! so saying our neighborhood is not far off ..
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Quoting 2712. hurricanes2018:
wow!! what is going on here with the east coast all in blue


That is going to be a formidable storm this weekend. Watch for a strong Nor'easter possibly transitioning to a tropical entity as it heads up the east coast. This bears more watching than Dorian I believe.

Link
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2739. LargoFl
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Current forecast discussion illustrates why "all" of the relevant factors have to click at the same time to achieve significant intensification.......NHC seems to think that moderate sheer in the short-term might off-set the slightly cooler SST's.

It's one big balancing act between Sal/SST's/and Sheer for any given storm at any given time during it's lifespan........Like a stack of dominos; some storms can overcome some issues and some cannot recover once a significant factor topples over.
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2737. Patrap
Member Since: July 3, 2005 Posts: 421 Comments: 127566
I'm not quite sure that we'll have this, but I expect a similar track for a certain extent. (until it reaches the island maybe)

And sorry if I annoyed people with that above comment, I just felt like no one would see it on the end of the last page, and I put a lot of thought into it. (:
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Just remember how difficult it is to predict intensity for tropical cyclones, especially ones as small as Dorian. Here's the first advisory forecast for Major Hurricane Michael last year.

INIT 03/2100Z 25.6N 42.2W 30 KT 35 MPH
12H 04/0600Z 25.8N 42.9W 35 KT 40 MPH
24H 04/1800Z 26.4N 43.7W 35 KT 40 MPH
36H 05/0600Z 27.3N 44.3W 35 KT 40 MPH
48H 05/1800Z 28.0N 44.5W 30 KT 35 MPH
72H 06/1800Z 28.5N 44.5W 25 KT 30 MPH...POST-TROP/REMNT LOW
96H 07/1800Z 29.5N 44.5W 20 KT 25 MPH...POST-TROP/REMNT LOW
120H 08/1800Z 30.5N 44.5W 20 KT 25 MPH...POST-TROP/REMNT LOW
Member Since: Posts: Comments:
Quoting 2724. opal92nwf:
(I moved this comment)

Wow, oh my goodness...The opening of the segment on the Weather Channel is BREAKING NEWS 4th Storm of the Season Tropical Storm Dorian will it threaten the US?

Now I am not dissing them for thinking it could eventually impact the US and for advertising that, but this is such a contrast to how people treated storms in years past such as hurricane Andrew in 1992. Watch how they actually don't say out loud that Andrew could hit South Florida in this clip. Even when it is 615 miles from Miami and heading due West, he uses general terms like "it will be in our neighborhood"...Amazing how times have changed. It's just a simple media technique to get people latched on to a storm thousands of miles away so that they will watch that television station.
img src="">


They really are irresponsible.
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2733. Dakster
Quoting 2729. LargoFl:
if that storm comes anywhere near florida the tree removal services are going to be making the big bucks huh..and imagine the rivers,lakes and streams..imagine..10-12 inches of MORE rain coming...and..we ALSO have that frontal system moving into florida just about the same time............this is not a good scenerio shaping up for soaking wet florida


Only because of all the non-native trees that are here now.

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Quoting 2678. HoraceDebussyJones:


You need to get off the Turnpike honey to see the real Jersey


My dear,I lived NJ for over 50 years. You can cut the pollution with a knife on hot summer days, especially in urban areas such as Camden. The air on the horizon is actually brown some days. It's a struggle to breathe. Pediatric asthma is rampant in places like Camden, NJ. I'll take tropical Florida downpours any day-we have virtually no ozone alert days in Tampa compared to Camden/Philly. Global warming is for real.
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its going up!! need to watch the east coast!
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Quoting 2725. hydrus:
That is why I was surprised that they had it at storm strength all the way across the Atlantic.
NHC weakened it from 60 mph to 45 mph.
Member Since: August 1, 2011 Posts: 28 Comments: 7903
2729. LargoFl
if that storm comes anywhere near florida the tree removal services are going to be making the big bucks huh..and imagine the rivers,lakes and streams..imagine..10-12 inches of MORE rain coming...and..we ALSO have that frontal system moving into florida just about the same time............this is not a good scenerio shaping up for soaking wet florida
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I do not see it going back down to 45MPH at all
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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.