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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Quoting 2321. CybrTeddy:
Also congratulations to the ECMWF for missing yet another tropical cyclone.
Lol.Well it did pick this up and at the strongest had it as a 40mph storm then sent it right into the strong high which is practically impossible..
Quoting 2322. allancalderini:
Washi we might get a hurricane after all XD.
Shhh don't say that...
Member Since: August 14, 2010 Posts: 10 Comments: 17081
I see we have Tropical Storm Dorian now. Not looking that bad at all this morning.

The second Cape Verde storm in July. This could mean something big down the road of the 2013 hurricane season. I wonder if we will end up breaking the blog again?
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If Dorian can gain strength I wonder if it would defy the challenges ahead (lower SSTs and moderate dryness) by creating its own 'tropical environment' as it heads westward and become a high end TS or cat 1 hurricane as it gets just north of the islands.
Member Since: June 16, 2005 Posts: 0 Comments: 1365
2325. Grothar
Hey, Levi.

Is this over you?



Member Since: July 17, 2009 Posts: 71 Comments: 26477
Link


Very tiny but has a very well organized circulation.
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2323. LargoFl
still no idea if this will hit florida or not huh?..maybe by the weekend they will know better.....
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Quoting 2310. washingtonian115:
For now you don't have to worry about any Andrew type system..

The GFS is still retarded...It sniffed this out and dropped it.I can't say I blame it with the only marginal conditions it has.
Washi we might get a hurricane after all XD.
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Also kudos to the ECMWF for missing yet another tropical cyclone.
Member Since: July 8, 2005 Posts: 259 Comments: 24169
Quoting 2306. VR46L:
Hmmm



Dorian has slowed down and is starting to temporarily move North of due west. The extra time is allow it to deepen far more than expected. and the update file confirms it has moved 0.1N in 4 hours and 0.9W.
Member Since: May 25, 2012 Posts: 0 Comments: 2043
Morning all! I see we have Tropical Storm Dorian. We're now up to speed with 2011 and 2012. Already up to 50mph too!

Member Since: July 8, 2005 Posts: 259 Comments: 24169
2318. SLU
Quoting 2287. Neapolitan:
Updated:

AL, 04, 2013072412, , BEST, 0, 140N, 290W, 45, 1002, TS, 34, NEQ, 40, 30, 0, 30, 1012, 150, 20, 0, 0, L, 0, , 0, 0, DORIAN, D,

Yowza...


Such a tight system can strengthen rapidly. If that "eye-like" feature persists we could be in for an interesting day.
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Quoting 2310. washingtonian115:
For now you don't have to worry about any Andrew type system..

The GFS is still retarded...It sniffed this out and dropped it.I can't say I blame it with the only marginal conditions it has.


I just get nervous when I see a forecasted track right into the bahamas. the water is warm.
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Quoting 2282. gulfshoresAL:
In 1964 As Cleo crossed Cuba it came off the northern coast as a tropical storm. Between the north coast of Cuba and landfall in Miami it went to. Cat 2, 100mph in approximately 100 mile stretch. NHC at the time contributed the rapid intensification to the Gulf Stream warm waters.


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Quoting 2287. Neapolitan:
Updated:

AL, 04, 2013072412, , BEST, 0, 140N, 290W, 45, 1002, TS, 34, NEQ, 40, 30, 0, 30, 1012, 150, 20, 0, 0, L, 0, , 0, 0, DORIAN, D,

Yowza...
He is stronger than what most think he would peak.
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2314. whitewabit (Mod)
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2311. KEEPEROFTHEGATE (Mod)
T.C.F.W.
04L/TS/D/CX
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Quoting 2289. MisterPerfect:
oh man...cape verde storm, moving west, looking tight.

not panicking yet. but we all remember Andrew.

pant pant pant
For now you don't have to worry about any Andrew type system..

The GFS is still retarded...It sniffed this out and dropped it.I can't say I blame it with the only marginal conditions it has.
Member Since: August 14, 2010 Posts: 10 Comments: 17081
dorian looks very healthy. his spin is extremly strong. come august im scaredd once we start getting them over less SAL and warmer water :P
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Quoting 2285. SouthernIllinois:
What? 50 MPH. Okay time for recon to confirm.

recon can only fly out to 50W max
Member Since: June 13, 2009 Posts: 2 Comments: 12150
2306. VR46L
Hmmm
Loop Embedded
Member Since: March 1, 2012 Posts: 0 Comments: 6927
Quoting 2287. Neapolitan:
Updated:

AL, 04, 2013072412, , BEST, 0, 140N, 290W, 45, 1002, TS, 34, NEQ, 40, 30, 0, 30, 1012, 150, 20, 0, 0, L, 0, , 0, 0, DORIAN, D,

Yowza...


Impossible it maybe reacting to the eye like feature thing its deepening and maybe it is who knows. I would think the NHC will split this in the middle and go with 1004mb and 45 mph Dorian. This does not make any sense I hope Avila does not come and say it could be defying the odds...
Member Since: May 25, 2012 Posts: 0 Comments: 2043
2304. Grothar
SAL not as strong, but that wave over Africa does look stronger than Dorian.



48 hour sea level pressure.



Possible blob develoment



Member Since: July 17, 2009 Posts: 71 Comments: 26477
Good Morning!
7:04 am (11:04 GMT)

The sun rises over Lantana as a helicopter flies overhead.

Oh, Dexter? I believe you said something to the effect that there was no way 98L would become Dorian? Dexter...?

Hmmmm. I maybe should have mentioned that one should consider the possibility that Dexter's forecasts could be based on the probability that he actually wants to eat crow.
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2302. LargoFl

...SPECIAL FEATURE...
TROPICAL DEPRESSION FOUR HAS FORMED FROM THE TRPCL WAVE-LOW
SYSTEM AND ITS CENTER IS LOCATED NEAR 13.9N 28.1W ABOUT 269 NM
WSW OF THE CAPE VERDE ISLANDS. ITS PRESENT MOVEMENT IS WNW AT 17
KT WITH MAXIMUM SUSTAINED WINDS OF 30 KT AND A MINIMUM CENTRAL
PRESSURE OF 1008 MB. THIS GENERAL MOTION IS EXPECTED TO CONTINUE
DURING THE NEXT COUPLE OF DAYS. SOME SLIGHT STRENGTHENING IS
EXPECTED DURING THE NEXT 48 HOURS...AND THE DEPRESSION IS
FORECAST TO BECOME A TROPICAL STORM LATER TODAY OR TONIGHT.

THE DEPRESSION IS EMBEDDED IN A HIGH MOIST ENVIRONMENT AT THE
LOWER AND MIDDLE LEVELS SUPPORTING A CLUSTER OF MODERATE
CONVECTION FROM 11N-15N BETWEEN 26W-30W AND SCATTERED MODERATE
CONVECTION ELSEWHERE FROM 06N-15N BETWEEN 24W-34W.
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Quoting 2292. Tazmanian:



ouch 50mph all ready



according to this it's 40

Link
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2300. whitewabit (Mod)
Just coming into view ..

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Quoting 2290. SouthernIllinois:

Andrew was late August.


Sure was. August 25th. It was my first hurricane experience. And what a monster it was. Will never forget it. I was 20 or so miles north of the eye. Scarred for life.
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2298. StormWx
Dorian is born. What an odd name for a storm. I've never met any named that before. If i had a choice for the D storm it would be Devondre, Da-Shawn or most likely De-wanda. But thats just me.
Member Since: July 10, 2013 Posts: 0 Comments: 967
Quoting 2287. Neapolitan:
Updated:

AL, 04, 2013072412, , BEST, 0, 140N, 290W, 45, 1002, TS, 34, NEQ, 40, 30, 0, 30, 1012, 150, 20, 0, 0, L, 0, , 0, 0, DORIAN, D,

Yowza...

woah hes taking some testosterone pressure down 4mb and goes from a 40MPH TS to a 50MPH looking on satellite that dry sport is starting to look more like an eye
Member Since: June 13, 2009 Posts: 2 Comments: 12150
Quoting 2282. gulfshoresAL:
In 1964 As Cleo crossed Cuba it came off the northern coast as a tropical storm. Between the north coast of Cuba and landfall in Miami it went to. Cat 2, 100mph in approximately 100 mile stretch. NHC at the time contributed the rapid intensification to the Gulf Stream warm waters.
By the way, good morning. As you can see I like to read everyone's comments I don't post much. I enjoy everyone's input....wrong or right it's their belief....I do also enjoy a Fresca while I'm reading.
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2295. LargoFl
showers moving in off the gulf..headed inland now........
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2294. GatorWX
Quoting Hurricanes305:


Hey beell, how are you this am, people dont realize that upper level winds wont be a big deal unless it starts moving like Chantal did. Trades are quite slower than that as are 6 days till August. Atlantic slowly becoming more favorable as August approaches.




Also sal has diminished exponentially in the last couple of days and no longer a issue that is why the NHC keeps it at TS strength.



Wow! It sho did.
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Quoting 2278. DataNerd:


This is probably one of the most relevant comments made this season on this blog and everyone should read it.

MJO is a huge factor here, especially in the formation of these early season cyclones here in July. This coupled with the abnormally strong high pressure pattern in the Atlantic and over the U.S. are two of the major large scale key players to be aware of this season.


Thanks a lot!!, The hurricane season can flip in a heartbeat as we enter August and it looks like its about to as conditions should only improve where low hanging CV system will funnel between 20N and 13N. And another system right after our Dorian could be possible with the same general path as Chantal and Dorian but even stronger. Long season ahead.
Member Since: May 25, 2012 Posts: 0 Comments: 2043
Quoting 2287. Neapolitan:
Updated:

AL, 04, 2013072412, , BEST, 0, 140N, 290W, 45, 1002, TS, 34, NEQ, 40, 30, 0, 30, 1012, 150, 20, 0, 0, L, 0, , 0, 0, DORIAN, D,

Yowza...



ouch 50mph all ready
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Quoting 2287. Neapolitan:
AL, 04, 2013072412, , BEST, 0, 140N, 290W, 45, 1002, TS, 34, NEQ, 40, 30, 0, 30, 1012, 150, 20, 0, 0, L, 0, , 0, 0, DORIAN, D,
Interesting. TD 4 randomly went from 35 mph to 50 mph.
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oh man...cape verde storm, moving west, looking tight.

not panicking yet. but we all remember Andrew.

pant pant pant
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2288. pcola57
Quoting 2270. 69Viking:


Yeah it was windy but I was glad the heavy rain only lasted a few minutes. Storm total for my place was half an inch. We're still under a 50% chance of storms today before it looks like we'll dry out a bit.


Morning 69Viking..
Yeah it reminded me of fronts I used to see in the Texas plains..
Not a whole lot of rain but wind starting in one direction and then a complete opposite direction..
I haven't seen that here that I recall..
Except in TC's..
Glad you are OK..

Quoting 2253. PensacolaDoug:


Last eve it was dying as it came thru... Eve before it came thru strong. Blew over everything on my patio and destroyed the 2nd umbrella this season. BBQ grill over as well.


Yeah it was dying but over here I got the strangest winds I've seen in awhile..
Thank goodness I had the foresight to collapse my umbrella before it came..
Not the BBQ!!..
Well battle scares on the BBQ are macho..
I salute it.. :)
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Updated:

AL, 04, 2013072412, , BEST, 0, 140N, 290W, 45, 1002, TS, 34, NEQ, 40, 30, 0, 30, 1012, 150, 20, 0, 0, L, 0, , 0, 0, DORIAN, D,

Yowza...
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2286. Grothar
Quoting 2255. hurricanes2018:
someone need to update this!!


You're not too far from the current forecast which is WNW.

Member Since: July 17, 2009 Posts: 71 Comments: 26477
Quoting 2278. DataNerd:


This is probably one of the most relevant comments made this season on this blog and everyone should read it.

MJO is a huge factor here, especially in the formation of these early season cyclones here in July. This coupled with the abnormally strong high pressure pattern in the Atlantic and over the U.S. are two of the major large scale key players to be aware of this season.
As you saw earlier this month if that high doesn't retreat north or weaken some those trades will be roaring no matter how moist the environment is..
Member Since: August 14, 2010 Posts: 10 Comments: 17081
98L wins the races too get too a td and name storm 1st


98E looks like it haveing a hard time
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Quoting 2251. indianrivguy:


1935
In 1964 As Cleo crossed Cuba it came off the northern coast as a tropical storm. Between the north coast of Cuba and landfall in Miami it went to. Cat 2, 100mph in approximately 100 mile stretch. NHC at the time contributed the rapid intensification to the Gulf Stream warm waters.
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Quoting 2265. hurricanes2018:
I do not see anything spinning there


Visible satellite imagery indicates center of rotation near or just west of Savannah, GA, this is where the center of vorticity is located, look at the CIMSS tropical weather page for the Atlantic and select 850mb vorticity, huge low level circulation present and low level clouds indicate a developing low is present not fully developed but developing, infant stages.
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Quoting 2245. SouthernIllinois:

You are like always the first to break the news with everything! Great work. You were on top of it announcing the news about the royal Baby. It's almost like you knew it before the baby was even born. :)

Natalie
Thanks...but Thing342 beat me. (And I didn't announced The Royal Baby; in fact, I haven't even mentioned it until now, as I care no more for that over-privileged infant than any of the 370,000 or so others born that same day around the world.)
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Quoting 2249. Hurricanes305:
Here is the MJO right in time for August. Hurricane season about to flip the switch. And I'm not liking our Atlantic High right now



Lmao at the downcasters who said no storms for the rest of the season.


This is probably one of the most relevant comments made this season on this blog and everyone should read it.

MJO is a huge factor here, especially in the formation of these early season cyclones here in July. This coupled with the abnormally strong high pressure pattern in the Atlantic and over the U.S. are two of the major large scale key players to be aware of this season.
Member Since: Posts: Comments:

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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.