95L growing more organized; Pakistan's Indus River flood peaking downstream

By: Dr. Jeff Masters , 2:23 PM GMT on August 21, 2010

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A tropical wave (Invest 95L) in the far eastern Atlantic about 350 miles southwest of the Cape Verdes Islands has become more organized this morning. Satellite loops show that the wave has some rotation, and heavy thunderstorm activity has increased in recent hours, after a period overnight with little change. Water vapor satellite loops show that there is some dry air to the north of 95L, but this dry air currently appears to be too far away to significantly interfere with development. The main impediment to development is the moderate 10 - 20 knots of wind shear over the system. The shear is forecast to remain in the moderate range through Monday, then decrease. This should allow 95L to develop into a tropical depression Monday or Tuesday. NHC is giving 95L a 30% chance of developing into a tropical depression by Monday morning. With 95L's recent increase in organization, these odds should probably be 50%.


Figure 1. Morning satellite image of 95L.

Forecast for 95L
A ridge of high pressure will force 95L to the west or west-northwest for the next five days, and the system should increase its forward speed from its current 5 - 10 mph to 15 - 20 mph by Monday. A series of two powerful troughs of low pressure are predicted to move off the U.S. East Coast next week and cross the Atlantic; these troughs should be able to pull 95L far enough to the northwest so that it will miss the Lesser Antilles Islands. If 95L stays weak or does not develop in the next five days, as predicted by the NOGAPS model, it has a chance of eventually threatening Bermuda. If 95L develops into a hurricane, as predicted by most of the computer models, it will probably recurve to the east of Bermuda and not threaten any land areas.

Elsewhere in the tropics
The ECMWF model is predicting formation of a tropical depression in the western Gulf of Mexico off the coast of Texas 6 - 7 days from now.

Pakistan's monsoon rains diminish; Indus River flood crest nears the coast
The flooding on Pakistan's largest river, the Indus, has slowly eased along the upper and middle stretches where most of the heavy monsoon rains fell in late July and early August. However, a pulse of flood waters from these heavy rains is headed southwards towards the coast, and flood heights have risen to near all-time record levels today at the Indus River gauge station nearest to the coast, Kotri (Figure 2.) The new flooding has forced the evacuation of an additional 150,000 people in Pakistan today. Flood heights at every monitoring station along the Indus have been the highest or almost the highest since records began in 1947. Fortunately, the monsoon has entered a weak to moderate phase, and heavy rain is not expected over the flood region over the next few days, according to the Pakistan Meteorological Department.


Figure 2. August flow rates along the Indus River, courtesy of the Pakistan Meteorology Department.

Some aid agencies helping with humanitarian crisis in Pakistan:

Doctors Without Borders

The International Red Cross

MERLIN medical relief charity

The mobile giving service mGive allows one to text the word "SWAT" to 50555. The text will result in a $10 donation to the UN Refugee Agency (UNHCR) Pakistan Flood Relief Effort.

Jeff Masters

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3336. breald
Why are you guys quoting Grother?
Member Since: May 28, 2008 Posts: 38 Comments: 5303
3335. Grothar
Quoting plywoodstatenative:
Grothar I thought that was from last night?


Probably is, it took me that long to post it.
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90 hours, moving NW:

Member Since: September 2, 2009 Posts: 130 Comments: 21194
3333. IKE
Quoting KEEPEROFTHEGATE:
you may want to stop showing that because they don't beleive it anyway.

next you will be accused of downcasting


LOL.

GFS is just slightly further north and east on the 12Z run...
Member Since: June 9, 2005 Posts: 23 Comments: 37860
Grothar I thought that was from last night?
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Quoting MiamiHurricanes09:
No it isn't. It is moving towards the NNW/N not the NE.


Yes, but the northeastern convective blob is moving WNW, both around the main convection and in its initial motion. Remember the anticyclone is positioned over that blob, so if that merges with the COC, then esentially so will that blob as it intensifies and gives the whole system a boost.
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3330. Grothar
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Quoting TropicalAnalystwx13:
12z GFS Hour: 060



12z GFS Hour: 066



12z GFS Hour: 072



12z GFS Hour: 078



.
Member Since: July 6, 2010 Posts: 113 Comments: 33677
Quoting StormChaser81:


I thought it had to do with the storms mass and amount of spin and the proximity of the two systems.
The NHC definition of the Fujiwhara effect:

The tendency of two nearby tropical cyclones to rotate cyclonically about each other.
Member Since: September 2, 2009 Posts: 130 Comments: 21194
I think most of us on here felt that this would not be a named system until Monday or even a TD

time is just balancing itself out is all
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Quoting Grothar:


Big shift west Grothar from last night.
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Quoting Stormchaser2007:
At 72 hours it seems to be moving NW


wnw to nw.
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Quoting Grothar:


Wow, one model gives 06L/Danielle a loop.
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Quoting Grothar:



Oh no, they are pointing at the USA!

Its not nice to point!
Member Since: July 6, 2010 Posts: 113 Comments: 33677
Quoting SunnyDaysFla:
Storms need to be tropical storm strength or greater for fujiwara effect to occur


I thought it had to do with the storms mass and amount of spin and the proximity of the two systems.
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Quoting plywoodstatenative:
what makes me wonder if we have a second coc that has developed under the convection. Remember storms of past that have raced away from shear and either relocated their coc's further south or jumped in a sense to escape shear. is that what we are looking at here?

That is a "Good Posiblity" of whats going own here....
I would also say everyone on here really needs to watch this one very closely.... It will be moving alot more westward and even a little south of west for a bit....

Taco :o)
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Quoting AstroHurricane001:




That wave has already exited Africa.


Thats not the wave.
Member Since: July 6, 2010 Posts: 113 Comments: 33677
Quoting AstroHurricane001:


Yup, the COC is moving DIRECTLY into the northeastern component.
No it isn't. It is moving towards the NNW/N not the NE.
Member Since: September 2, 2009 Posts: 130 Comments: 21194
3318. Grothar
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Quoting kmanislander:


The models have a longer time horizon and draw conclusions based upon the data input prior to the run. The current motion is expected to be a short term one BUT if it takes the center appreciably further North than forecasted then the new center position will go into the next set of model runs and may result in a shift to the right.

What you are seeing in the satellite imagery is within half an hour generally of being real time. Data in the last set of model runs is several hours old.
Thanks for your sharing your Knowledge,great information!
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Miami, I am a canes fan born, bred, and will die as one.

The question is this, what is going to tap into those Caribbean temps? Scenario 1: This storm recharges itself and moves north towards CONUS. The wave behind it because of atmospherical conditions moves into the Caribbean. Scenario 2 has both systems following the High. Scenario 3 has nothing. What sounds more likely given what we have right now in shear values, TCHP levels, and steernig winds. What is the most likely outcome?
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At 72 hours it seems to be moving NW
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3314. HadesGodWyvern (Mod)
** WTPQ20 BABJ 221500 ***
SUBJECTIVE FORECAST
TD 05 INITIAL TIME 221500 UTC
00HR 16.1N 112.5E 998HPA 16M/S (30 kts)
P12HR WNW 12KM/H
P+24HR 17.4N 110.2E 985HPA 25M/S=

China Meteorological Administration
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Quoting AstroHurricane001:




That wave has already exited Africa.


actually the axis of the wave is still over the coast of Africa, should exit tonight
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Quoting MiamiHurricanes09:
That's why I said, I ain't goin' there. :) back to the tropics. Here's an image of 06L, lol:



Yup, the COC is moving DIRECTLY into the northeastern component.
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3311. Relix
Next 12 hours will be VERY interesting. This was an unexpected move. Let's see how it goes for now. A new COC could form, current one would then get "dressed", etc. Things got complicated now though and a recurve seems less likely. I still stand by the fact the Northern Antilles won't even feel rain, but I'll see how things change in the next day or so.
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Quoting plywoodstatenative:
How far away is that second wave that is supposed to be exiting Africa?

The question becomes this, might be a little farfetched but...: Could the coc that has moved away in some way or another catch up with the wave that is exiting Africa and merge?




That wave has already exited Africa.
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12z GFS Hour: 060



12z GFS Hour: 066



12z GFS Hour: 072



12z GFS Hour: 078

Member Since: July 6, 2010 Posts: 113 Comments: 33677
Storms need to be tropical storm strength or greater for fujiwara effect to occur
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At 54-66 hours on the 12z GFS 06L continues to move towards the WNW but begins to slow down.
Member Since: September 2, 2009 Posts: 130 Comments: 21194
TAFB forecast

2 systems:

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If I recall the CMC Vorticity Model, indicates the system to the NE will be absorbed into TD-6.
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Quoting plywoodstatenative:


Exposed like UM? Except for a wide receiver or two, the gators have nothing. Now if you really want to get into it, how about all the transfers?
That's why I said, I ain't goin' there. :) back to the tropics. Here's an image of 06L, lol:

Member Since: September 2, 2009 Posts: 130 Comments: 21194
How far away is that second wave that is supposed to be exiting Africa?

The question becomes this, might be a little farfetched but...: Could the coc that has moved away in some way or another catch up with the wave that is exiting Africa and merge?
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Quoting kmanislander:
It is going to take a few hours before we see how the shear scenario plays out and that makes for a good time to take a break.

Off to do some "outdoor " stuff.

Will be back later.


Yeah, time to do a water change on the 125 gal.
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Quoting plywoodstatenative:
what makes me wonder if we have a second coc that has developed under the convection. Remember storms of past that have raced away from shear and either relocated their coc's further south or jumped in a sense to escape shear. is that what we are looking at here?


If that happens and we have two or even three COCs, then we could be looking at a fujiwara and merge that causes the storm to become an annular hurricane.
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12z GFS Hour: 054

Member Since: July 6, 2010 Posts: 113 Comments: 33677
The official BWS Marine forecast, gives TD-6 a more westerly track.

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TD-6 could be wandering long enough that synoptic pattern changes appreciably..this one may be a great study before its done...
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3297. Relix
It would be bad if a new COC formed under the blob of convection to the west. It has happened in the past ('sup Fay!) and it can happen again.
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Quoting Hurricanes101:
TD 6 will be fine, it just needs time to get away from the other disturbance

to me in the long run, this is a bad thing as the models continue to trend westward, a weaker system may not recurve at all


Regardless its not exactly having a great day.

This will slow the development process down.

Plus its still going to have problems with these other systems, so close to it.
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3295. KEEPEROFTHEGATE (Mod)
Quoting IKE:
you may want to stop showing that because they don't beleive it anyway.

next you will be accused of downcasting
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Quoting MiamiHurricanes09:
That means it is exposed not decoupled. If it were decoupled the mid-level and lower-level circulation would be split up into two and heading into different directions. What it is is exposed. When it is exposed it is distanced from the convection. Try not to confuse the two.


Maybe the two convective areas will merge around the circulation as it heads in between the two, and then the strengthening wave behind it pushes the whole storm farther south.
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Quoting MiamiHurricanes09:
I ain't goin' there...it's not like UF is gonna do better. :)


Exposed like UM? Except for a wide receiver or two, the gators have nothing. Now if you really want to get into it, how about all the transfers?
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Quoting IKE:


Good point. I'll give you a "+" for that post!
Thank you, that answer my questions...
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It is going to take a few hours before we see how the shear scenario plays out and that makes for a good time to take a break.

Off to do some "outdoor " stuff.

Will be back later.
Member Since: August 19, 2006 Posts: 0 Comments: 15949
48 hours/2 days:

Member Since: September 2, 2009 Posts: 130 Comments: 21194
Quoting tornadolarkin:
What is causing the circulation to become exposed?


Maybe it's the dry air to its east and slight shear from the circulation over the northeastern component.
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Out to 48 hours on the 12z GFS.

At 15-16N and moving WNW
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3287. calder
Quoting tornadolarkin:
What is causing the circulation to become exposed?


north easterly wind shear of 30 knots. Wind shear is the difference in winds between altitude levels and works to 'rip apart' the storm. It is forecast to drop in 24 hours. TD 6 will not be going away!
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Quoting Stormchaser2007:
The center had moved pretty much N since the last frame. That disturbance to the N is really causing trouble.



Maybe the center will merge with the NE component convection.
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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.

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