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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Quoting weatherwatcher12:

So the circulation has made its way into the Caribbean?


It is possible... the next few Sat images we get will let us know if that's the case. It is possible (obviously due to shear) that a weak developing low could have tried to have gotten organized but it detached itself from the main convection and if that's the case then it should die out soon.
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599. HadesGodWyvern (Mod)
heh

I never clicked on the satellite link on the NHC page before. =P
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Repeating for clarity..

Tropical Floater 1 - Visible Loop

Just because the AOI is in the Floater 1 parked view,dosent make it a invest.

If a new Invest occurs,NOAA would have it here .


Atlantic and Caribbean Tropical Satellite Imagery
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Quoting BurnedAfterPosting:


there is no 98L
It is not shown as a number but the 60 wave is named "invest" on the floater.
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Quoting GeoffreyWPB:
You are persistent Reed! Despite the evidence. Stand up for what you believe!


LMAO
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You are persistent Reed! Despite the evidence. Stand up for what you believe!
Member Since: September 10, 2007 Posts: 0 Comments: 10578
Quoting Tazmanian:



i think am a rare of that


Just checking lol.
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97 is das kaput.

Its behind enough Dry air to make a New Sahara.

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Quoting BurnedAfterPosting:


shear will be much more favorable in the Caribbean
Thanks. Maybe by next year I will have a clue what everything means. Always liked to weather watch but just started paying attention the last couple of years.
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Quoting Stormchaser2007:


But not an official one.



i think am a rare of that
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I'm still watching 97L, it's moving into a much better environment and the shear map proves it. Notice the Tropical Wave near the Islands is really moistening the environment as well. We'll see what happens tonight.
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That's wierd. When I go on the NHC site and click satllite, and then click loop for the invest, it shows the blob near the Antilles and not Invest 97L?98L now?
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Quoting Tazmanian:
this is now a Invest





But not an official one.
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Tropical Floater 1 - Visible Loop

Just because the AOI is in the Floater 1 parked view,dosent make it a invest.

If a new Invest occurs,NOAA would have it here .


Atlantic and Caribbean Tropical Satellite Imagery
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Quoting Tazmanian:
this is now a Invest





not officially
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this is now a Invest



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Quoting stormwatcherCI:
What will that mean if it lifts out ?


shear will be much more favorable in the Caribbean
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Quoting stormwatcherCI:
What will that mean if it lifts out ?

Significantly less shear
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Quoting WxLogic:
One interesting thing to note... is that the INVEST area along with the high pressure in the N ATL are producing a pronounced pressure gradient... Wind gust reports of between 25 to 28 MPH. On last feature will be the slight cyclonic turning depicted in the E Carib see S/SE of PR which would be the source of the this.

So the circulation has made its way into the Caribbean?
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Quoting BurnedAfterPosting:


That is exactly what is happening
What will that mean if it lifts out ?
Member Since: October 9, 2008 Posts: 0 Comments: 8242
One interesting thing to note... is that the INVEST area along with the high pressure in the N ATL are producing a pronounced pressure gradient... Wind gust reports of between 25 to 28 MPH. On last feature will be the slight cyclonic turning depicted in the E Carib see S/SE of PR which would be the source of the this.
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579. HadesGodWyvern (Mod)


The low pressure area over northwest Bay of Bengal and adjoining coastal areas of north Orissa and West Bengal persists. The system is likely to become more marked within next 48 hours.
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Quoting wunderkidcayman:
97 is dead and 98 is born on the nhc sat page no more 97l but invest and it shows the wave that is the closer one to the islands


there is no 98L
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Quoting weatherwatcher12:

Looks like the TUTT is lifting out


That is exactly what is happening
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97 is dead and 98 is born on the nhc sat page no more 97l but invest and it shows the wave that is the closer one to the islands
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Quoting beell:
CIMSS 5 Day Shear Loop

Looks like the TUTT is lifting out
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574. beell
CIMSS 5 Day Shear Loop
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Central Atlantic - Funktop Color Infrared Loop
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From the graphics you all are posting there is still a whole lot of something out there whatever it is called. IMHO the season is getting cranked up. Much different looking stuff coming off of Africa - Just a matter of time till one of them fires up. For those who keep track of my disaster work, I'm in Marion, Illinois where I talked to a couple today who were in the storm in early May. 110 mph winds for over an hour. Forests have huge trees down everywhere, blue roofs still all over - although the event was a straight line it sure made a heck of a mess. Sorry to hear some of our good guys got banned - seems to me there's room for all of our opinions and a little courtesy goes a long way.
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Atlantic 2009

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Central Atlantic - Infrared Channel 2 Loop
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567. beell
One difference in the two waves. 97L never got free of the ITCZ.

Like SJ said last night-if shear is lessening it is from 50 to 40 or 40 to 30. That is some very strong shear.
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560. reedzone 8:25 PM GMT on July 18, 2009
Quoting KYhomeboy:
Guys, dont be fooled. That convection was caused because of the combination of the wave itself and the TUTT. The coulds appear to be faning out because they are being sheared. That moisture will remain away from the center of the invest and maybe become absorbed by ex 97L. Look at the most recent visible and ir loops and you will see convection increasing where it should be in order for this to develop. Also, look at ex 97L...the lower level cloud deck appears to be re-organizing from the mess it was earlier on today. I would not be too quick to throw this one out of the window


I've been trying to explain that, I'm not pulling the plug on 97L just yet. New convection forming, deep to. We'll have to see what happens.
I agree completely, though I'm certainly no expert.
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Ack,coff,..Dusty dry air.


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UW - CIMSS
ADVANCED DVORAK TECHNIQUE
ADT-Version 7.2.3
Tropical Cyclone Intensity Algorithm

----- Current Analysis -----
Date : 18 JUL 2009 Time : 193000 UTC
Lat : 22:16:52 N Lon : 113:28:33 E


TROPICAL CYCLONE OVER LAND
NO ADT ANALYSIS AVAILABLE

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EX-97L catching up to the Antilles invest.
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You and Taz called it Ben.
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Central Atlantic - Water Vapor Loop
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Quoting KYhomeboy:
Guys, dont be fooled. That convection was caused because of the combination of the wave itself and the TUTT. The coulds appear to be faning out because they are being sheared. That moisture will remain away from the center of the invest and maybe become absorbed by ex 97L. Look at the most recent visible and ir loops and you will see convection increasing where it should be in order for this to develop. Also, look at ex 97L...the lower level cloud deck appears to be re-organizing from the mess it was earlier on today. I would not be too quick to throw this one out of the window


I've been trying to explain that, I'm not pulling the plug on 97L just yet. New convection forming, deep to. We'll have to see what happens.
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Looks like another quiet day in the Atlantic .
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558. HadesGodWyvern (Mod)
The Increasing Gale or Storm Signal, No. 9, is in force.

At 4 a.m., Typhoon Molave was centred about 50 kilometres
north-northwest of Hong Kong Observatory (near 22.7 degrees
north 113.9 degrees east) and is forecast to move west or
west-northwest at about 25 kilometres per hour across the
Pearl River Estuary entering the western part of Guangdong.

Molave has made landfall for a few hours, and winds near
its centre has started to weaken. Nevertheless, gale or
storm force winds are still affecting Hong Kong. The
Observatory will replace the Increasing Gale or Storm
Signal, No. 9 by the No. 8 Southwest Gale or Storm Signal
shortly.
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Wow... love the storm clouds outside my front door. Besides the rain, that's what I miss most during a drought -- those awesome clouds. Too bad it's a tease and will stay south of me :(
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Quoting Acemmett90:

the wave at 60 has become a pacman that eats other waves and or invests

lmao, how you doing Ace?
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From a lurker...I wonder what influence the tropical wave would have on ex97 if the westward motion continues at 10-15ks.
Wouldn't it catch the wave and help moisten the enviornment for redevelopement?
Thanks, CypressJim
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Quoting StormJunkie:
The 60w wave is not an invest at this point Ace.


And I suspect it will never be one. Everytime there is a big blow up of convection, everyone jumps on it, but the entity really to watch is Ex 97L IMO.
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553. HadesGodWyvern (Mod)
Japan Meteorological Agency
Tropical Cyclone Advisory #26
SEVERE TROPICAL STORM MOLAVE (T0609)
3:00 AM JST July 19 2009
============================================

Subject: Category Two Typhoon Overland Southern China

At 18:00 PM UTC, Severe Tropical Storm Molave (980 hPa) located at 22.6N 114.2E has 10 minute sustained winds of 60 knots with gusts of 85 knots. The storm is reported as moving west at 17 knots.

Dvorak Intensity: T3.5

Storm Force Winds
===============
50 NM from the center

Gale Force Winds
================
150 NM from the center

Forecast and Intensity
=======================
24 HRS: 24.5N 108.9E - Tropical Depression
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Ex-97L seems to be holding its own for now... since it's attempting to produce some convection just as it was dropped by NHC.
Quoting beell:
Pretty big jog to the N for the ITCZ.

TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
205 PM EDT SAT JUL 18 2009

...ITCZ...

THE ITCZ AXIS IS CENTERED ALONG 10N14W 9N29W 10N34W 11N42W 8N46W
13N60W. SCATTERED MODERATE CONVECTION IS WITHIN 120 NM OF A LINE
FROM 10N12W TO 6N24W. SIMILAR CONVECTION IS FROM 6N-9N BETWEEN
47W-52W.


Hehe... the ITCZ wants get back on track!!!
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Central Atlantic - Rainbow Color Infrared Loop
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About JeffMasters

Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.