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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The circulation is not moving further from the convection, it is moving closer as it heads towards the NNW. Check it out here.
Member Since: September 2, 2009 Posts: 130 Comments: 21194
Quoting Stormchaser2007:


I doubt this circulation dies.

IF it does...reformation is a long and complicated process.


Seems to me the 2010 season has worn on some people that they automatically are assuming that is going to happen
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Quoting JupiterFL:


Yup, I don't thing that thing is going to continue in opposite directions. Something has to give. My guess is that COC is DOA.


I doubt this circulation dies.

IF it does...reformation is a long and complicated process.
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Quoting AstroHurricane001:


Notice that the anticyclone is located directly over the northeastern convection. If it carries that convection with it and the COC continues drifting north, we could see a merger or the two convective areas with the COC, and a subsequent repulsion of dry air. This could cause rapid strengthening, causing the new wave to swing to the northeast of this storm.


a megacane.....LOL
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Quoting Stormchaser2007:


The exposed dry COC is heading directly into the path of the northeastern blob, and the anticyclone directly over it.
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3230. txjac
Quoting TexasHurricane:
ok, I guess nobody wants to answer my question....


Wish someone would be it's not as exciting as TD06. If its something that should be watched then they would be talking about it ...at least thats how I read it on here
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3229. KEEPEROFTHEGATE (Mod)
Quoting IKE:


Getting further away from the convection.
its in trouble at the moment if it continues well that will put the blog in overload
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3228. Vero1
Quoting TexasHurricane:
ok, I guess nobody wants to answer my question....


TROPICAL WEATHER DISCUSSION
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
805 AM EDT SUN AUG 22 2010

GULF OF MEXICO...
BROAD UPPER LEVEL ANTICYCLONIC CIRCULATION COVERS THE BASIN.
THIS UPPER LEVEL FEATURE IS PROVIDING A DRY EASTERLY FLOW ALOFT
OVER MUCH OF THE GULF. LOW TO MID-LEVEL INSTABILITY AND UPPER
LEVEL DIFFLUENCE PROVIDED BY THE UPPER LEVEL RIDGE IS GENERATING
SCATTERED SHOWERS AND TSTMS OVER THE EASTERN GULF E OF
88W...INCLUDING THE FLORIDA PENINSULA AND FLORIDA STRAITS.
SCATTERED SHOWERS AND THUNDERSTORMS ARE ALSO OVER THE BAY OF
CAMPECHE S OF 20N. THIS ACTIVITY IS ASSOCIATED TO TROPICAL
DEPRESSION NINE-E CURRENTLY LOCATED ABOUT 110 NM S OF THE GULF
OF TEHUANTEPEC GENERATING BROAD CYCLONIC FLOW AND CONVECTION
THAT REACHES AS FAR NORTH AS THE BAY OF CAMPECHE. THE REMAINDER
OF THE GULF IS UNDER THE INFLUENCE OF THE EASTERN FLOW ALOFT
MENTIONED ABOVE AND THIS SUPPORTS A 1016 MB SURFACE HIGH
CENTERED OVER THE CENTRAL GULF NEAR 26N91W. CLEAR SKIES ARE
NOTED ELSEWHERE ON NIGHT VISION SATELLITE IMAGERY UNDER LIGHT
ANTICYCLONIC WINDS.
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Quoting TexasHurricane:
ok, I guess nobody wants to answer my question....


What was your question?
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Quoting IKE:


Getting further away from the convection.


Yup, I don't thing that thing is going to continue in opposite directions. Something has to give. My guess is that COC is DOA.
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Quoting TexasHurricane:
ok, I guess nobody wants to answer my question....


Nothing will likely come from it.
Member Since: July 6, 2010 Posts: 113 Comments: 32338
Quoting MiamiHurricanes09:
Shear slowly beginning to decrease around 06L. At 13:15UTC mainly 20-30 knots of east-northeasterly shear was affecting the system, now at 14:15 UTC mainly 20 knots (with 30 knots affecting the extreme southeastern quadrant) of east-northeasterly shear is affecting the system. The upper level high to the northeast also appears to be meandering westward.



Notice that the anticyclone is located directly over the northeastern convection. If it carries that convection with it and the COC continues drifting north, we could see a merger or the two convective areas with the COC, and a subsequent repulsion of dry air. This could cause rapid strengthening, causing the new wave to swing to the northeast of this storm.
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Quoting JupiterFL:


I have contacts but thanks for checking. Looks like you need a new barber.


LOL!
Member Since: July 6, 2010 Posts: 113 Comments: 32338
Quoting KEEPEROFTHEGATE:
i have it zoomed right in kman the naked swirl appears to be movin nne while the convection continues w some thing is happening thats why no upgrade they may have seen it but too late to add it to the already wriiten up advs.


I just took a look at the close up vis loop and what I see is a short term motion that is almost NNW. There is the illusion of the exposed center heading off to the NNE due to the due West motion of the high cloud tops. Run the loop and cover the left half of the circulation with a piece of paper to obscure the cloud motion and you will see what I mean.

This is a classic case of a system being sheared out but it may only be temporary depending on the interaction with the system to its NE and the progression of the high.

Just my opinion FWIW.
Member Since: August 19, 2006 Posts: 0 Comments: 15842
Quoting IKE:


That just silenced the..."it's moving west" crowd.


I don't care which way it is moving right now, only where it winds up. And the track keeps shifting West, Smugcaster General.
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3219. IKE
Quoting KEEPEROFTHEGATE:


Getting further away from the convection.
Member Since: June 9, 2005 Posts: 23 Comments: 37858
will be interesting to see how long this NNW jog continues
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Quoting TropicalAnalystwx13:


Far? You need glasses


I have contacts but thanks for checking. Looks like you need a new barber.
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Quoting AstroHurricane001:


Amazingly, the East Pacific has been the most active NHem basin this year. The Atlantic and West Pacific has had an equal number of depressions. However, since most of the extra heat and energy is in the Atlantic, once the dry air gets depleted the season will erupt with a bang.
Almost everything that popped over there did so because it couldn't pop in the ATL.... including TS Frank.
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ok, I guess nobody wants to answer my question....
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Out to 6 hours on StormVista
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Shear slowly beginning to decrease around 06L. At 13:15UTC mainly 20-30 knots of east-northeasterly shear was affecting the system, now at 14:15 UTC mainly 20 knots (with 30 knots affecting the extreme southeastern quadrant) of east-northeasterly shear is affecting the system. The upper level high to the northeast also appears to be meandering westward.

Member Since: September 2, 2009 Posts: 130 Comments: 21194
Quoting SLU:
Still a depression

ASCAT HIRES


WINDSAT


Impressive
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Quoting JupiterFL:
With as far off as that COC is, my guess is that one is toast. I would think this will need a new COC somewhere closer to the convection.


Far? You need glasses
Member Since: July 6, 2010 Posts: 113 Comments: 32338
3210. KEEPEROFTHEGATE (Mod)
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Quoting AstroHurricane001:


Very little dry air in the Atlantic.


TD-6 has a little bit of dry air right on his eastern side, that's what has limited the convection and some northeast shear hasn't helped either.
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I wouldn't get my panties in a bunch over the LLC moving north...

Watching the TPW, you can see that Friday this whole area was elongated west to east.

Yesterday it started tilting from southwest to northeast.

And today the broader circulation is becoming more north/south as the strong flow to the north forces it to rotate. It also appears that the southwesterly monsoon flow is weakening and also becoming more southerly.

The circulation will retighten and become vertically stacked later today or tonight. Then the forecast strengthening should commence.

Member Since: June 15, 2010 Posts: 0 Comments: 291


Amazingly, the East Pacific has been the most active NHem basin this year. The Atlantic and West Pacific has had an equal number of depressions. However, since most of the extra heat and energy is in the Atlantic, once the dry air gets depleted the season will erupt with a bang.
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3206. SLU
Still a depression

ASCAT HIRES


WINDSAT
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With as far off as that COC is, my guess is that one is toast. I would think this will need a new COC somewhere closer to the convection.
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The 12z GFS is starting.

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WOW, amazing upper-level anticyclone above the former Cape Verde swirl, meaning that the bit northeast of the storm might actually intensify and undergo a Fujiwara with the main system. Shear over the main COC is actually about 10 kt. The former CV swirl and the new wave both have about 5 kt.
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3202. IKE
Member Since: June 9, 2005 Posts: 23 Comments: 37858
It will probably slowly turn back more to a WNW to NW heading over the course of the day. TD6 imo will improve very little today and maybe even somewhat into tomorrow. While this looks good it will likely allow for a better shot at the east coast down the line.
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Ike, I think they need the glasses. Whats your feel about the models runs that put something in your neighborhood
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Quoting P451:
Decoupling occurring?

Didn't expect that!


Not every temporarily exposed eye is evidence of incipient decoupling. Moderate shear--which is affecting TD6 at the moment--can blow some of the convection away from the CoC of a weak but strengthening system without anything so deadly as decoupling taking place. Look at Colin; his naked core was exposed via shear for days, yet no decoupling was happening.
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Member Since: September 2, 2009 Posts: 130 Comments: 21194
Convection of td6 moving almost wsw and the coc moving nw/nnw, will the coc relocate under the heaviest convection or will new convection fire around the coc, could make quite a difference in where this might be headed imo.
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3196. KEEPEROFTHEGATE (Mod)
Quoting kmanislander:
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.
i have it zoomed right in kman the naked swirl appears to be movin nne while the convection continues w some thing is happening thats why no upgrade they may have seen it but too late to add it to the already wriiten up advs.
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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?
It's always POSSIBLE. Now LIKELY is much too early to say. Most storms in pre-Danielle's position don't hit land, but a few of them do, and some of those hit FL. It makes the storm worth watching for Floridians, but not something to get "worried" about before, say, Wednesday or Thursday.
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Quoting sammywammybamy:


Very little dry air in the Atlantic.
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Decouplement is not the right term for this.

More like exposure.

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3191. IKE
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


You need glasses...or I need a new pair...Link
Member Since: June 9, 2005 Posts: 23 Comments: 37858
Quoting MiamiHurricanes09:
Looks to be bending NNW in the very last image of RGB.


The upper-level convection is moving W, the lower-level circulation is moving NNW, and the former spin from Cape Verde is moving WNW.
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Is this what may become an issue down the road in the western GOM?

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I knew it!I saw it moving N.
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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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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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