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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2300. Gorty
6:11 PM GMT on July 19, 2009
When you look at this model, http://cimss.ssec.wisc.edu/tropic/real-time/atlantic/winds/wg8midshr.html

Do you look at both levels, or just one or the other to determine if something will form?
Member Since: November 8, 2008 Posts: 12 Comments: 1058
2299. Gorty
5:57 PM GMT on July 19, 2009
A couple models with the latest run does strenthen AL97. But, the HWARF and GFDL is "saying" anything. If those two arn't saying anything, then it probably won't develop. Because isn't the HWARF and the GFDL trustworthy models?

The SHF5 model brings this thing to a Cat 1 at 120 hours.
Member Since: November 8, 2008 Posts: 12 Comments: 1058
2298. all4hurricanes
4:52 PM GMT on July 19, 2009
Quoting WAHA:

Omar october Paloma november

I know but I meant august or later. anyway the main point is the history of hurricanes from last year do not support the notion of a cyclone developing in the eastern Caribbean in July
Member Since: March 29, 2008 Posts: 0 Comments: 2373
2297. SELAliveforthetropic
4:33 PM GMT on July 19, 2009
I vote B
Member Since: August 12, 2006 Posts: 0 Comments: 60
2296. juniort
4:25 PM GMT on July 19, 2009
Thank you StormwatcherCI for your welcome
Member Since: July 19, 2009 Posts: 0 Comments: 69
2295. stormwatcherCI
4:20 PM GMT on July 19, 2009
Grothar and juniort welcome and you will get all the information you need and then some. There are some very knowledgeable people here and then there are the trolls so take some comments with a grain of salt.
Member Since: October 9, 2008 Posts: 0 Comments: 8399
2294. stormwatcherCI
4:17 PM GMT on July 19, 2009
Quoting HurricaneSwirl:


yes but only omar could form in the east caribbean. all the others could not get started in the east caribbean. well fay did too be she wasn't particularly strong, she just was moving very slow and landfalled in florida 4 times XD
Gustav formed around 67 w which I think is still basically eastern Caribbean. Has anyone noticed the flare-up of convection with the blob that moved through the islands yesterday. I think it is s of Puerto Rico now.
Member Since: October 9, 2008 Posts: 0 Comments: 8399
2293. juniort
4:14 PM GMT on July 19, 2009
i should probably introduce myself here and say that I'm new here, so folks help me along. i am also watching 97L carefully, but no infor as yet from Barbados met service
Member Since: July 19, 2009 Posts: 0 Comments: 69
2292. PORTCHARLOTTE72
4:06 PM GMT on July 19, 2009
dr steve lyons didnt spend more than 2 seconds discussing 97l in the tropical update it was like it wasnt even there he spent more time talking about the rain in florida i live in swest florida it hasent rained here in 3 weeks
2291. BenBIogger
4:00 PM GMT on July 19, 2009
Quoting JRRP:
where is the dead zone?


The Eastern Caribbean
Member Since: March 19, 2009 Posts: 0 Comments: 1421
2290. stormpetrol
3:59 PM GMT on July 19, 2009
97L is starting to ventilate and still headed due west , at least on close up visible sat imagery. TD by 11pm tonight if this keeps up , imo.
Member Since: April 29, 2007 Posts: 0 Comments: 7935
2289. StormJunkie
3:59 PM GMT on July 19, 2009
Dr M's new blog

Member Since: August 17, 2005 Posts: 26 Comments: 16874
2288. HurricaneSwirl
3:58 PM GMT on July 19, 2009
Quoting Drakoen:


hmm, the main blob of convection in the center looks like its expanding. interesting.
Member Since: July 7, 2008 Posts: 2 Comments: 3237
2285. Drakoen
3:57 PM GMT on July 19, 2009
New Blog
Member Since: October 28, 2006 Posts: 57 Comments: 30578
2284. PensacolaDoug
3:57 PM GMT on July 19, 2009
Mornin' SJ. Something to track finally!
Member Since: July 25, 2006 Posts: 0 Comments: 581
2283. sporteguy03
3:57 PM GMT on July 19, 2009
Stormjunkie this observation is key as well, let's see if the winds turn to the NE and goes counter-clockwise when 97L comes near if so there might be something low level there.


Grantley Adams, Barbados (Airport)
Updated: 55 min 29 sec ago
87 °F
Partly Cloudy
Humidity: 62%
Dew Point: 76 °F
Wind: 23 mph from the East
Wind Gust: -
Pressure: 29.99 in
Visibility: 15.0 miles
Clouds: Few 1772 ft
Mostly Cloudy 29528 ft
(Above Ground Level)

Member Since: July 7, 2005 Posts: 0 Comments: 5364
2282. Lower4216
3:57 PM GMT on July 19, 2009
Okay .. what does all of this mean for someone who is leaving Thursday out of Mobile, AL on a cruise to Cozumel? Is it gonna be bumpy?
Member Since: August 29, 2006 Posts: 0 Comments: 27
2281. pottery
3:57 PM GMT on July 19, 2009
Trinidad weather now
90 f
47% humid
11 miles vis
wind ENE 10 mph
pressure 1015

not much in that...
Member Since: October 24, 2005 Posts: 0 Comments: 24467
2280. WxLogic
3:57 PM GMT on July 19, 2009
I wouldn't bother much looking at how 12Z GFS handles this one as it did not initialize it correctly. 00Z should be a good run... we're lucky of 18Z comes out to be a decent one.
Member Since: August 14, 2008 Posts: 4 Comments: 4978
2279. JRRP
3:56 PM GMT on July 19, 2009
where is the dead zone?
Member Since: August 16, 2007 Posts: 0 Comments: 5998
2278. hurricane23
3:56 PM GMT on July 19, 2009
Quoting Drakoen:
That upper level trough is either going to make or break 97L.


Hey Drak,

Lol little sucker just noticed 97 is back up just looking at obs out there and for now i cant fine a surface circulation but convection has somewhat consolidated overnight i'll give it that.Now as far as its future track a deepening trof off low pressure along the southeast coast should induce shear and a northwesterly turn eventually.

PS...Just ran an infrared loop and yes some pretty decent outflow is starting to take shape.
Member Since: May 14, 2006 Posts: 8 Comments: 13807
2277. IKE
3:56 PM GMT on July 19, 2009
Quoting jurakantaino:
Dr. Lyons did his best to avoid mentioning the "invest", his words:" In the Mean time there is another wave approaching the island that will bring a couple of showers to the antilles"


jeez doc...go surf....

Member Since: June 9, 2005 Posts: 23 Comments: 37858
2276. HurricaneSwirl
3:56 PM GMT on July 19, 2009
Quoting DDR:

Lets hope it doesn't rapidly intensify,the islands will welcome the rain,thats for sure.


dont think it will, its moving a little too fast, has an upper level trough that needs to move, heat potential isn't that high but i could be wrong about that part.
Member Since: July 7, 2008 Posts: 2 Comments: 3237
2275. Cavin Rawlins
3:56 PM GMT on July 19, 2009
Yea, SJ I'm seeing what appears to be a LLC so that buoy info should be interesting and the TWO.
Member Since: July 24, 2005 Posts: 407 Comments: 19076
2274. WAHA
3:56 PM GMT on July 19, 2009
Quoting all4hurricanes:

but those storms were all in august except for dolly but she formed in the western Caribbean

Omar october Paloma november
2273. Drakoen
3:56 PM GMT on July 19, 2009
Quoting Grothar:
Thanks to all for the answers on the SAL. Since I am a novice to this blog, I shall probabaly ask more questions, than provide opinions. Hope no one minds. There has been mention of a trough over SE U.S. Does anyone have any idea as to the effect, if any, it may have on the direction of ANY systems which approach the Caribbean? If I am correct, the current models indicate a more southerly track. Also, please excuse me my writing, since English is not my first language.


Your syntax, diction, and grammar is better than a lot here lol.
Member Since: October 28, 2006 Posts: 57 Comments: 30578
2272. STORMMASTERG
3:56 PM GMT on July 19, 2009
Quoting jurakantaino:
Dr. Lyons did his best to avoid mentioning the "invest", his words:" In the Mean time there is another wave approaching the island that will bring a couple of showers to the antilles"
Plus upper winds are not favorable for formation further west/twc is a channel of no reliability,they only make you seem to think that.
2271. AussieStorm
3:55 PM GMT on July 19, 2009
Wx Update, E Caribbean, Sat18, 9a

Morning graphical QuickScat: ABCs & Venezuela W of 66W ENE-E@13-20 with a few squalls to 35k, mainly N of 12N / E of 66W to Trinidad & Grenada E@0-10 with isolated squalls to 30k / just W of Windwards ENE-E@10-17 / W of Leewards ENE@16-22 with scattered squalls to 30k / Virgins & PuertoRico ENE@15-20 / DomRep ENE-E@12-17.



TropicalWAVE near 60W:
--Strong, high-amplitude WAVE near E Caribbean along 17N/59W...12N/63W, moving W-WNW@15. To gauge risk for Tropical LO formation, I look for the following 3 criteria: squalls that are abundant, focused, and persistent at the focal point. This morning, squalls have become more-abundant & focused at 16N/59W. If these squalls persist over the next 12-24 hrs, a Tropical LO could form.

--Typically, such squall activity surges & wanes several times before becoming persistent-enough to generate a self-sustaining Tropical LO. Thus, it is unlikely (but not impossible - I'd estimate a 10% chance) a LO will form before this area moves W of VirginIslands & PuertoRico tomorrow. Wind-shear of 40-50k is decreasing, but should help prevent formation of a Tropical LO.

--NOAA this morning began mentioning a low (less-than-30%) chance of Tropical LOW formation over next 48hrs with this feature.

--Beyond tomorrow, Apex of WAVE should lie somewhere near the GreaterAntilles (Hispanola & Cuba), which, combined with likelihood of persistent wind-shear, should prevent formation of a Tropical LOW.

Link
Member Since: September 30, 2007 Posts: 9 Comments: 15940
2270. Drakoen
3:54 PM GMT on July 19, 2009
Member Since: October 28, 2006 Posts: 57 Comments: 30578
2269. juniort
3:54 PM GMT on July 19, 2009
no news here in Barbados as yet
Member Since: July 19, 2009 Posts: 0 Comments: 69
2268. Grothar
3:54 PM GMT on July 19, 2009
Thanks to all for the answers on the SAL. Since I am a novice to this blog, I shall probabaly ask more questions, than provide opinions. Hope no one minds. There has been mention of a trough over SE U.S. Does anyone have any idea as to the effect, if any, it may have on the direction of ANY systems which approach the Caribbean? If I am correct, the current models indicate a more southerly track. Also, please excuse me my writing, since English is not my first language.
Member Since: July 17, 2009 Posts: 71 Comments: 26558
2267. jurakantaino
3:54 PM GMT on July 19, 2009
Dr. Lyons did his best to avoid mentioning the "invest", his words:" In the Mean time there is another wave approaching the island that will bring a couple of showers to the antilles"
Member Since: July 31, 2008 Posts: 0 Comments: 730
2266. HurricaneSwirl
3:54 PM GMT on July 19, 2009
Quoting WAHA:

Dolly, Fay, Gustav, Omar and Paloma all formed in the carribean last year.


yes but only omar could form in the east caribbean. all the others could not get started in the east caribbean. well fay did too be she wasn't particularly strong, she just was moving very slow and landfalled in florida 4 times XD
Member Since: July 7, 2008 Posts: 2 Comments: 3237
2265. moonlightcowboy
3:53 PM GMT on July 19, 2009
Quoting SavannahStorm:
lol, Dr. Lyons barely even mentioned 97L...


They're short on time, commercials and all for travel, etc. Only soundbites, like the evening news. LOL. They hardly mention anything any more unless is has been named a TD. I don't watch them anymore, consequently.
Member Since: July 9, 2006 Posts: 184 Comments: 29610
2264. DDR
3:53 PM GMT on July 19, 2009
Quoting Weather456:
I do believe we have LLC or one is forming


Lets hope it doesn't rapidly intensify,the islands will welcome the rain,thats for sure.
Member Since: April 27, 2007 Posts: 14 Comments: 1703
2263. all4hurricanes
3:53 PM GMT on July 19, 2009
Quoting WAHA:

Dolly, Fay, Gustav, Omar and Paloma all formed in the carribean last year.

but those storms were all in august except for dolly but she formed in the western Caribbean
Member Since: March 29, 2008 Posts: 0 Comments: 2373
2262. sporteguy03
3:53 PM GMT on July 19, 2009
Quoting WxLogic:


Would be funny if it has the same fate...


Actually the name "Chris" has had a history of downfalls as well, I remember Dr.M doing a blog on him in 2006.
Member Since: July 7, 2005 Posts: 0 Comments: 5364
2261. aquak9
3:53 PM GMT on July 19, 2009
2229- bam shallow for another 24-48, then a whole new ballgame. Bam mid another 24-36, then bam deep runs, maybe lgem.

Who knows, maybe GFS will sober up by then.
Member Since: August 13, 2005 Posts: 169 Comments: 26126
2260. StormJunkie
3:53 PM GMT on July 19, 2009
Morning PDoug, good to see ya.

456 - pressure has started to fall at 41040 as well. Should continue to drop as 97 approaches. It should be an interesting buoy to watch today...A fair clip north of the system, but still should provide some data.
Member Since: August 17, 2005 Posts: 26 Comments: 16874
2259. Cavin Rawlins
3:53 PM GMT on July 19, 2009
Dead zone? I often wonder where that came from especially after Felix, Charley, Omar, etc.
Member Since: July 24, 2005 Posts: 407 Comments: 19076
2258. TampaMishy
3:53 PM GMT on July 19, 2009
Quoting naplesdreamer28:
I don't like the looks of those tracks. A Charlie type tracking.
You always say that.
Member Since: July 30, 2007 Posts: 0 Comments: 1474
2257. hurricane23
3:53 PM GMT on July 19, 2009
.
Member Since: May 14, 2006 Posts: 8 Comments: 13807
2256. Drakoen
3:52 PM GMT on July 19, 2009
Quoting WxLogic:


Would be funny if it has the same fate...


I was thinking that too lol
Member Since: October 28, 2006 Posts: 57 Comments: 30578
2255. SavannahStorm
3:52 PM GMT on July 19, 2009
lol, Dr. Lyons barely even mentioned 97L...
Member Since: September 22, 2005 Posts: 18 Comments: 2343
2254. PensacolaDoug
3:51 PM GMT on July 19, 2009
Nothin like a good invest to get the blog moving at light speed.....
Member Since: July 25, 2006 Posts: 0 Comments: 581
2253. Cavin Rawlins
3:51 PM GMT on July 19, 2009
Quoting sporteguy03:


Do the Windward Islands have their own weather service that broadcasts on tropical systems about to effect them just wondering if there was any news on the invest in that region.


I'm in the Leewards but they are monitoring the disturbance.
Member Since: July 24, 2005 Posts: 407 Comments: 19076
2252. Chicklit
3:51 PM GMT on July 19, 2009
Dr. Masters promised an update this afternoon; mostly likely will appear after the 2 pm discussion.
Member Since: July 11, 2006 Posts: 14 Comments: 11358
2251. WAHA
3:51 PM GMT on July 19, 2009
Quoting PensacolaDoug:
"Ana" by this time tomorrow? Could be at the rate its spinning up now but, storms that are not very organized before getting to the eastern Carrib don't usually develope until they get to western Carrib. Eastern Carrib is usually kind of a "dead zone" for developement.
But it sure is looking impressive right now.

Dolly, Fay, Gustav, Omar and Paloma all formed in the carribean last year.
2250. WxLogic
3:51 PM GMT on July 19, 2009
Quoting all4hurricanes:

what about north of the carribean cause thats where this thing is supposed to be heading

heres an eerily similar Ana from 79


Would be funny if it has the same fate...
Member Since: August 14, 2008 Posts: 4 Comments: 4978

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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.