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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Quoting weatherman12345:

could this effect florida in any way or is it out of the question...i know its to early to tell but is it possible?


Too early to tell as it is still days away from any land area, need to see how far North it gets and where it turns influences the TD feels in 4-5 days.
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Quoting IKE:
There can be no arguing where the COC of TD6 is, because it's exposed....



Right on cue!!!
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Quoting KEEPEROFTHEGATE:
06L/TD/XX
LOOKS TOO ME LIKE A DECOUPLING IS OCCURING



What Kaman wrote makes sense.
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Word of the day: Fish
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Decoupling is a more appropriate label for what happens when the upper and lower levels of the circulation become unhinged, so to speak, and head off in different directions or one outruns the other. Interaction with very high terrain when a system comes ashore will also lead to decoupling as the low level circulation is destroyed.

That is not what is happening here. The TD is undergoing moderate shear which has displaced some of the convection from being directly overhead the center of circulation. Both the upper and lower level circulation are still linked together and headed off in the same direction at approximately the same speed.

The displacement is probably temporary and we should see the satellite presentation improve over the course of the next 6 hours or so.
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12z GFS is about to start.
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Quoting MiamiHurricanes09:
Looks to be bending NNW in the very last image of RGB.


It is doing that.
Member Since: July 6, 2010 Posts: 113 Comments: 31525
3178. Dakster
Quoting galvestonhurricane:
TD 6 looks like it will eventually undergo RI and REM.


REM?? Rapid Eye Movement?
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Quoting AstroHurricane001:
Wow, this is like three interacting systems:



Could you imagine them merging into one?

Wow!
Member Since: July 6, 2010 Posts: 113 Comments: 31525
Quoting TropicalAnalystwx13:


No its not
Looks to be bending NNW in the very last image of RGB.
Member Since: September 2, 2009 Posts: 130 Comments: 21091
3175. calder
Quoting Stormchaser2007:


the western strucutre is very impressive though, the season begins folks :)
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Wow. Looks like the recurve issue might be a thing of the past! Guess storm was right about td6 after all.
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TD 6 looks like it will eventually undergo RI and REM.
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Quoting Stormchaser2007:


I doubt its actually decoupling. The NHC would have mentioned that in their discussion.

Some people may just be...overreacting

THE DEPRESSION IS EXPECTED TO REMAIN UNDER THE INFLUENCE OF MODERATE
EAST-NORTHEASTERLY SHEAR FOR THE NEXT 24 HOURS OR SO...BUT
THEREAFTER THE UPPER-LEVEL ENVIRONMENT BECOMES MORE CONDUCIVE FOR
STRENGTHENING.

The NHC does acknowledge the shear lets see if the TD improves after 24 hours as forecast.
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Good Morning Everyone!

Here's betting the GFS shows a continued trend further west in the next run...

The NAM from this morning has fairly strong ridging (321 or 3210 meter 700mb height circle above Puerto Rico and east of North Carolina) at 84 hours or Wednesday evening. At this time, the GFS from this morning has the storm to the southeast of this ridging. Nowhere to go but west.

Member Since: June 15, 2010 Posts: 0 Comments: 291
Wow, this is like three interacting systems:

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Quoting wunderkidcayman:
hey guys if you look on the last 3 frames of the RGB loop and zoom in on the COC you can see that it is starting to resume it westerly track oh yeah also speed up the loop


No its not
Member Since: July 6, 2010 Posts: 113 Comments: 31525
3165. KEEPEROFTHEGATE (Mod)
06L/TD/XX
decoupling detected
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3164. Dakster
Quoting ElConando:


It couldn't be doing what I think its doing?


Why not?
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Quoting Stormchaser2007:


I doubt its actually decoupling. The NHC would have mentioned that in their discussion.

Some people may just be...overreacting
Exactly. The Discussion clearly (lol) states that the circulation remains well-defined. If it was decoupled it wouldn't be well-defined.
Member Since: September 2, 2009 Posts: 130 Comments: 21091
Quoting P451:
Decoupling occurring?

Didn't expect that!


I doubt its actually decoupling. The NHC would have mentioned that in their discussion.

Some people may just be...overreacting
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3161. Dakster
Quoting weatherman12345:
Why is it that models are pulling this west at the end of the runs and not recurving this out to sea now?? what changes have occured?


Environmental.

Look at the steering maps that were previously posted. Steering layers have changed.

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Quoting atmoaggie:
Huh, I don't think naked was in the forecast...at least not mine.


I always leave a chance for scattered nakedness in my forecast.
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Quoting weatherman12345:
Why is it that models are pulling this west at the end of the runs and not recurving this out to sea now?? what changes have occured?


according to the NHC discussion the trof will be too far East to pull a complete recurvature, in other words the TD will be left behind awaiting a steering flow.
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The 12z GFS will probably be farther West.

Just how much farther West is the key.
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hey guys if you look on the last 3 frames of the RGB loop and zoom in on the COC you can see that it is starting to resume it westerly track oh yeah also speed up the loop
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Quoting atmoaggie:
Huh, I don't think naked was in the forecast...at least not mine.



It couldn't be doing what I think its doing?
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Quoting sporteguy03:
BY DAYS 4 AND
5 THERE IS GREATER UNCERTAINTY WITH THE TRACK FORECAST DEPENDING ON
HOW THE MID-LATITUDE LONGWAVE PATTERN EVOLVES IN RELATION TO WHEN
THE DEPRESSION ACTUALLY BEGINS MOVING WESTWARD. THE GLOBAL MODEL
GUIDANCE IS IN GOOD AGREEMENT SHOWING AN AMPLIFYING TROUGH NEAR 45W
BY DAY 4...WHICH SHOULD BE TOO FAR EAST TO INDUCE SIGNIFICANT
RECURVATURE.



This is a Frances forecast discussion

INITIAL MOTION IS SLIGHTLY NORTH OF WEST AT AROUND 15 KT. DYNAMICAL
MODEL PREDICTIONS INDICATE A WEAKENING OF THE MID-TROPOSPHERIC
RIDGE TO THE NORTH OF THE TROPICAL CYCLONE OVER THE NEXT SEVERAL
DAYS...DUE TO THE INCURSION OF A TROUGH INTO THE CENTRAL ATLANTIC.
THIS TROUGH IS AT RATHER HIGH LATITUDES HOWEVER...SO IT IS NOT
LIKELY TO PLAY A DIRECT ROLE IN STEERING THE TROPICAL CYCLONE.
NOTWITHSTANDING...THE TRACK GUIDANCE GENERALLY SHOWS A SLOWING OF
THE FORWARD SPEED AND A TURN TOWARD THE NORTHWEST LATER IN THE
FORECAST PERIOD.
THE NHC TRACK FORECAST FOLLOWS THIS SCENARIO...BUT
IS A LITTLE TO THE SOUTH AND FASTER THAN MOST OF THE MODELS IN VIEW
OF THE CURRENT MOTION WHICH SEEMS TO BE ACCELERATING TO THE WEST
AS WE SPEAK.

see the similarities
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Quoting weatherman12345:
Why is it that models are pulling this west at the end of the runs and not recurving this out to sea now?? what changes have occured?


Maybe the points I mentioned in post 3058 ??
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Quoting TruthCommish:


I think the NHC will name the system when they have the data to verify Tropical Storm intensity. It's a really good method!


Weaker Trof, Stronger Ridge
Member Since: July 6, 2010 Posts: 113 Comments: 31525
Quoting MiamiHurricanes09:
LOL, ok, ok, ya' got me. I just didn't understand it with the steering flow but it turns out that the disturbance to the northeast of 06L is influencing its motion.


I just find it funny. I was telling people that this short term change wouldn't make that much of a difference because of it not being due to a major steering shift but nobody listened to me lol

whatever this needs to bear watching. I see people criticizing the Frances crowd again and I would like to reiterate that I am a member of the Frances crowd not because I think the track will be the same as Frances but I see the same complex synoptic pattern shaping up that led to a quick major shift of the models. Granted the models in 2010 are much better than those in 2004 but it could still happen and I think we are seeing it already. Interesting to see if the 12z gfs continues the trend sw. The GFS likes to swing. It is one of the few models in which the track can change drastically run by run. Just watch it closely
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3148. KEEPEROFTHEGATE (Mod)
NMFC Norfolk Tropical Feed
As of SUN 22 Aug 2010 15:00:02Z
Active Tropical Warnings in the Atlantic, Caribbean, or Gulf of Mexico
TROPICAL DEPRESSION 06L.SIX
Active Tropical Warnings in the Northwest Pacific, North Indian Ocean, Central Pacific, Eastern Pacific, or Southern Hemisphere
Current Central/Eastern Pacific Tropical Systems
Tropical STORM 09E.FRANK
2010 Storms
All Active Year
Atlantic
06L.SIX
East Pacific
09E.FRANK
Central Pacific

West Pacific
06W.SIX
Indian Ocean

Southern Hemisphere
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3147. bappit
Quoting KEEPEROFTHEGATE:
06L/TD/XX
LOOKS TOO ME LIKE A DECOUPLING IS OCCURING

The discussion mentions moderate wind shear. The northward motion must be adding some secret sauce shear.
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00z ECMWF, 240 hours. Pretty impressive cyclone (940mb).

Member Since: September 2, 2009 Posts: 130 Comments: 21091
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Quoting katrinakat5:
im not surprised the NHC has only sat. to go on...it looks to me deep banding is wrapping around the center and it continues to become better organized...however no land mass is being threatened so they can take there time on naming this...i think when recon goes down to check it out it will be a hurricane...the envelope is huge on this system.


I think the NHC will name the system when they have the data to verify Tropical Storm intensity. It's a really good method!
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Joe Bastardi Part 2

Now the flip side of this.. is alot of storms like to turn out quickly. Felix in 1995.. Bonnie, which hit the NC coast in 1998 turned out quickly.

I will be in later today to do the videos. A look at the euro ensembles

http://www.ecmwf.int/products/forecasts/d/charts/medium/eps/ensm/essential!MSLP !North%20America!240!pop!od!enfo!plot_ensm_essential!2010082200!!/

show how far west the variance is by the color spread, as several runs have the storm approaching the NC coast day 10...

The 500 mb shows this too

http://www.ecmwf.int/products/forecasts/d/charts/medium/eps/ensm/essential!Geop otential%20at%20500hPa!North%20America!240!pop!od!enfo!plot_ensm_essential!2010 082200!!/

I apologize for not yet having the moveable type so you dont have to copy and paste the links.

This is an intereting test in that my theory that the ky to getting the season to start was to raise pressures in N America is something that is causing people some degree of consternation ( they disagree). Thats fine, but we will see. There is one heck of a cool shot coming into the nation this week before the summer ends boiling for much of the nation and its interesting to note that in previous years that the change in the weather pattern, or greater variances, suddenly would invite storm development. Which makes sense, because give a set of parameters that WERENT PRODUCING STORMS if you change that, it would make sense to go the other way.

One of the "problems" with TD 6 and perhaps the models is there are two systems.. one off to the northeast, and the modeling may be trying to pick out a mid point between the two. In addition , the cloud shot shows a big system coming off Africa this morning behind this:

http://www.nhc.noaa.gov/satellite.shtml

In any case, this is "tugging" at td 6, retarding quicker westward movement so its now on the east side of its thunderstorms, with a look of the opposite kind of shear that we normally look to inhibit storms. However once the energy is bundled, and this is what the euro is seeing and why it develops this into a major hurricane on the 00z run, it will be free to deepen. This usually takes a few days ( again a look in the Pacific at typhoon evolution is what one needs to do. Many systems out there are double and even triple areas of low pressure within a large "envelope" Interestingly enough, Dora, the 64 storm I referenced, started in much the same manner

A look at the wide cloud shot of the atlantic examplifies my comment a few days ago that before a parade, one can "hear" the band coming before you see it. Like magic, 4 systems show up from the southeast Pacific to Africa

http://www.ssd.noaa.gov/goes/east/tatl/avn-l.jpg

The one on the Pacific side of Mexico is not a US concern but is a case of in close development for Mexico and a problem there.

One sees the depression and what may be two systems, and of course the bomb coming off Africa. Also thunderstorms lurk in the northeast gulf. Notice also if you will how waves with virtually no cloudiness before now have some thunderstorms with them, once they approach and then get by 60 west.

For the gulf.. while there is modeling showing development in the northeast gulf, this trough leaving on
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Surfmom,haven't been out in a while might fish tomorrow,one things for sure alot more sharks on local beaches,reports of a 6foot bull being caught recently....imo could be a new aoi forming off tpa
Overnight assoicated w a trough split....oh yea i see you changed the color of ur jogging hat!!!:)
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The disturbance at the top of this image is really interfering with 06L. Once that's gone the WNW movement will resume and it should intensify.


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3138. SLU
You must be at least 18 years of age to view the following image.

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Quoting Twinkster:
I find it funny that last night when the GFS had it going NNW in the short term everyone was criticizing it when the NNW movement is actually the correct motion LOL
LOL, ok, ok, ya' got me. I just didn't understand it with the steering flow but it turns out that the disturbance to the northeast of 06L is influencing its motion.
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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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