Pakistan monsoon floods kill at least 800

By: Dr. Jeff Masters , 5:56 PM GMT on July 31, 2010

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The deadliest weather disaster of 2010 is unfolding in Pakistan, where heavy monsoon rains have triggered flooding that has left at least 817 people dead. A death toll may reach 3000, according to the local head of Pakistan's largest rescue service, and more monsoon rains are on the way. Monsoon floods have also hit southeastern Afghanistan hard, where at least 64 have been killed. The heavy rains were caused by a monsoon depression (also called a monsoon low) that formed over the Bay of Bengal on July 24, crossed over India, and reached Pakistan on July 27. The rains increased in intensity over the next two days, peaking on July 29 and 30, when a low pressure system that moved across Pakistan from the west enhanced rainfall from the monsoon depression. Over the 3-day period July 28 - 30, torrential rains in excess of 8 inches (203 mm) fell in many regions of northwest Pakistan, resulting in that nation's worst floods since at least 1929. Rainfall amounts at two stations in the catchment basins of the Jhelum River and Indus River reached 19.49" (495 mm) for the month of July, and 7.56" (192 mm) fell in a single day, July 30, at Tarbela.

A monsoon depression is similar to a tropical depression, but forms in the Indian Southwest Monsoon over the Bay of Bengal. Like tropical depressions, monsoon depressions are hundreds of miles in diameter, have nearly calm winds near the center, and can have sustained winds of 30 - 35 mph. Four monsoon depressions originated in the Bay of Bengal in 2009; the average is 6 - 7. A new monsoon depression developed over the Bay of Bengal yesterday, and is headed westward towards Pakistan. Heavy rains from this new monsoon depression will begin affecting Pakistan on Monday, according to the Pakistan Meteorological Department.


Figure 1. The heavy thunderstorms of a monsoon depression lie over northwestern Pakistan near Islamabad in this visible satellite image taken by NASA's MODIS instrument on July 29, 2010. Image credit: NASA.

Tropical Atlantic may get active by mid-week
The Invest 90L tropical wave off the coast of Africa has grown disorganized, and NHC is no longer generating forecast tracks for the system. A tropical wave that moved of the coast of Africa Thursday is in the eastern Atlantic near 10N 25W, a few hundred miles south of the Cape Verdes Islands. This morning's 12Z run of the NOGAPS model predicts that this wave will develop into a tropical storm by Wednesday, and reach the Lesser Antilles Islands Friday. This morning's 12Z run of the GFS and ECMWF models predict that an area of disturbed weather near 8N 37W, in the east-central Atlantic, will develop into a tropical storm that will move through the Lesser Antilles on Thursday. Wind shear is low to moderate, sea surface temperatures are at record highs, and the dust and dry air of the Saharan Air Layer (SAL) are far enough to the north of these disturbed areas to potentially allow formation of a tropical storm. However, the Madden-Julian Oscillation currently favors downward motion over the tropical Atlantic, which will act to decrease the chances of tropical storm formation. NHC is giving a 30% chance that a tropical depression will form by Monday afternoon from one of these areas of disturbed weather.

Next update
I'll have an update Monday morning at the latest.

Jeff Masters

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2470. xcool
scott39 .WHAT YOU MEANING .I HAD TOMAY BEERS LOL
Member Since: September 26, 2009 Posts: 2 Comments: 15620
2469. JLPR2
Quoting KoritheMan:


Though 240 hours is admittedly, rather far out, and I'm honestly not willing to speculate on a track beyond seven days, particularly with a system that isn't even fully developed yet, the large scale weather pattern across North America greatly favors the ECMWF's solution. The GFS is latching onto this as well, though it still keeps an unreasonably weak subtropical ridge later in the period.


How many days would it take for 91L to be in PR's vicinity?
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Quoting 7544:
looks like we might see a bonnie track in play and a lot stronger than bonnie was hang on


Agreed. But let's not get ahead of ourselves. The system hasn't even developed yet, even if it is likely.

Let's just say...it has the potential to surpass Bonnie. Which it does.
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2467. scott39
Quoting xcool:
::(
Do you have a generater for this season?
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Quoting scott39:
Thanks, What about this far out?


Though 240 hours is admittedly rather far out, and I'm honestly not willing to speculate on a track beyond seven days, particularly with a system that isn't even fully developed yet, the large scale weather pattern across North America greatly favors the ECMWF's solution. The GFS is latching onto this as well, though it still keeps an unreasonably weak subtropical ridge later in the period.
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West florida coast hugger would be bad scenario for them
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2463. xcool
91L GET BIGG
Member Since: September 26, 2009 Posts: 2 Comments: 15620
2462. xcool
::(
Member Since: September 26, 2009 Posts: 2 Comments: 15620
2461. 7544
looks like we might see a bonnie track in play and a lot stronger than bonnie was hang on
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2460. scott39
Quoting KoritheMan:


It's performed exceptional this year. Last year, too. It nailed Bill's sharp poleward track before any of the models did. In fact, the general consensus was for a hit from Florida to North Carolina initially, but the ECMWF didn't buy that. We all thought it was crazy. Turns out we were crazy.

That should lend some credence to the ECMWF, I think, particularly after its superb performance with Alex.
Thanks, What about this far out?
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Quoting xcool:
let see model trends tomorrow hmmm


Yeah. Lets hope EURO doesn't stay locked into that path or strength.
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Quoting JLPR2:


Well that's good for me, bad for the Bahamas.


And for me.
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Quoting scott39:
So is the EMCFW the platinum standard for models this season?


It's performed exceptional this year. Last year, too. It nailed Bill's sharp poleward track before any of the models did. In fact, the general consensus was for a hit from Florida to North Carolina initially, but the ECMWF didn't buy that. We all thought it was crazy. Turns out we were crazy.

That should lend some credence to the ECMWF, I think, particularly after its superb performance with Alex.
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Quoting scott39:
So is the EMCFW the platinum standard for models this season?


Unfortunately.
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2455. xcool
let see model trends tomorrow hmmm
Member Since: September 26, 2009 Posts: 2 Comments: 15620
2454. JLPR2
Quoting KoritheMan:


I hope you stay safe too. And right now, I personally think it passes to the north of you.


Well that's good for me, bad for the Bahamas.
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2453. scott39
So is the EMCFW the platinum standard for models this season?
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Quoting xcool:
homelesswanderer hey


Hey xcool. :)
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Quoting Levi32:
Anyway, the good news tonight is that this is not a backyard development threat and we here in the United States have over a week to watch this before being threatened. The northeast Caribbean islands only have 5 days before it will be in their area, and it is still unclear how strong it may be by then. At least long-track storms can be prepared for well in advance.

I've got to head to bed. Goodnight all.


Night.
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Quoting JLPR2:


But I really hope it doesn't come here, my dad is leaving for NY some days so my mom would probably be more nervous and stressed than normal if 91L payed a visit.


I hope you stay safe too. And right now, I personally think it passes to the north of you.
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2448. xcool
homelesswanderer hey
Member Since: September 26, 2009 Posts: 2 Comments: 15620
2447. JLPR2
Quoting KoritheMan:


Denial isn't just a river in Africa. ;)


But I really hope it doesn't come here, my dad is leaving for NY some days so my mom would probably be more nervous and stressed than normal if 91L payed a visit.
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Quoting JLPR2:


I say it but I get the automatic:
Eh... that's not coming here!
LOL!


I used to get that out of my hubby. He used to not evac with us. I made him for Rita. Good thing too. She put an oak tree and the roof down on the bed he slept in during other evacs me and the kids did. Hes a believer now. :)
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Quoting JLPR2:


I say it but I get the automatic:
Eh... that's not coming here!
LOL!


Denial isn't just a river in Africa. ;)
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2444. JLPR2
Quoting JavPR:

hehe...my dad is a little bit like me he gets excited(maybe more because of his free days from work he is a teacher lol)...but mom and the rest go thru stages....

stage 1...that's not coming
stage 2...it's still a few days away
stage 3...ok, let's buy some things just to be safe
stage 4...what the HELL ARE WE GOING TO DO
stage 5...(if it comes)...this is your fault you wanted this(if it doesn't)...TOLD YOU SO!



haha!
My dad gets stuck in phase 1 and my mom goes thru all the phases LOL!
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2443. JLPR2
Quoting Levi32:


I don't think so, but who knows.

Notice though even the CIMSS maps don't agree with themselves....

Here's the 03z "regular" vort map:



And the rapid-scan one for 03z:



See the difference? There are different ways to analyze the vorticity and the CIMSS maps are not infallable, and in fact I have seen them wrong many times. They use satellites to generate most of the data points and when convection blows up like it is tonight, we can't see the low-level winds and neither can the satellite so they have to fill in with numerical model data, and that's never perfect.


You got a big point there, they are different!
Well then We will have to wait for visible images to be sure we got a LLC under that convection. :)
Although we probably do, something was spinning under there before sunset.
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2442. Levi32
Anyway, the good news tonight is that this is not a backyard development threat and we here in the United States have over a week to watch this before being threatened. The northeast Caribbean islands only have 5 days before it will be in their area, and it is still unclear how strong it may be by then. At least long-track storms can be prepared for well in advance.

I've got to head to bed. Goodnight all.
Member Since: November 24, 2005 Posts: 635 Comments: 26547
Quoting Levi32:
ECMWF 168 hours from the Raleigh site....I got a typo it was 986mb here not 966. However, notice the white block lol. Despite such a high pressure the isobars are very tightly packed, and this indicates to us that the model is showing a relatively small storm, reminiscent of storms such as, yes, Andrew that have come east of Florida. It's not a big giant. Believe it or not a small storm may actually make sense out of this system, despite the large-looking size it has right now.



Well, these storms do shrink as they organize and consolidate. Bonnie was very small and came out of a large wave. Alex was a monster wave, but only a medium sized storm
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Based on the synoptic scale pattern over North America, the ECMWF's track seems plausible, I hate to say.

Still a long ways out, though. But the CMC is much too poleward, and the NOGAPS much too equatorial.
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2439. JavPR
Quoting JLPR2:


I say it but I get the automatic:
Eh... that's not coming here!
LOL!

hehe...my dad is a little bit like me he gets excited(maybe more because of his free days from work he is a teacher lol)...but mom and the rest go thru stages....

stage 1...that's not coming
stage 2...it's still a few days away
stage 3...ok, let's buy some things just to be safe
stage 4...what the HELL ARE WE GOING TO DO
stage 5...(if it comes)...this is your fault you wanted this(if it doesn't)...TOLD YOU SO!

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2438. Levi32
Quoting JLPR2:


But that vort wasn't there today, at the start it was an elongated area then it became more compact and kept moving upwards away from the convection which puzzled me and then the new circle of 850mb vort developed, I dont think it is the same one and I think 90L was dragged away by the TW, the two little vorts to 91L's NE are the TW and 90L


I don't think so, but who knows.

Notice though even the CIMSS maps don't agree with themselves....

Here's the 03z "regular" vort map:



And the rapid-scan one for 03z:



See the difference? There are different ways to analyze the vorticity and the CIMSS maps are not infallable, and in fact I have seen them wrong many times. They use satellites to generate most of the data points and when convection blows up like it is tonight, we can't see the low-level winds and neither can the satellite so they have to fill in with numerical model data, and that's never perfect.
Member Since: November 24, 2005 Posts: 635 Comments: 26547
2437. JLPR2
Convection is popping in individual cells around the stronger and coldest cloud tops.
91L seems ready to get going.
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Quoting Levi32:
Unfortunately, the ECMWF solution is very possible, as it usually is. It is still too far out to say, but the models are laying out the possibilities and the concern is that the GFS continues to underestimate the ridging near the eastern US because of its poor job on the MJO, and the ECMWF once it locks on usually has the right idea. Remember it was farthest south on Alex and ended up dead on.


Lol. I had to break out my sigh guy. :)

SmileyCentral.com
But seriously the ECMWF is scary accurate this year.
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2435. xcool
image not work
Member Since: September 26, 2009 Posts: 2 Comments: 15620
2434. Levi32
ECMWF 168 hours from the Raleigh site....I got a typo it was 986mb here not 966. However, notice the white block lol. Despite such a high pressure the isobars are very tightly packed, and this indicates to us that the model is showing a relatively small storm, reminiscent of storms such as, yes, Andrew that have come east of Florida. It's not a big giant. Believe it or not a small storm may actually make sense out of this system, despite the large-looking size it has right now.



192 hours taking it towards the keys:

Member Since: November 24, 2005 Posts: 635 Comments: 26547
2433. JLPR2
Quoting JavPR:

i was thinking the same thing...but then again everytime I mention here at home that we should begin preparations so early they look at me like if I was a wishcaster....maybe they've been looking at this blogs LOL


I say it but I get the automatic:
Eh... that's not coming here!
LOL!
Member Since: Posts: Comments:
2432. xcool
Member Since: September 26, 2009 Posts: 2 Comments: 15620
2431. JLPR2
Quoting Levi32:


No 11N 31W would be more associated with the incoming wave from behind. I've also noticed errors in the CIMSS vorticity analysis today because of all the convection (satellites can't see the low-level clouds) so those maps can't be trusted down to the detail. It's the same low as 90L. The only reason it's 91L is because they deactivated 90L and then had to re-designate it because the system still wants to develop.


But that vort wasn't there today, at the start it was an elongated area then it became more compact and kept moving upwards away from the convection which puzzled me and then the new circle of 850mb vort developed, I dont think it is the same one and I think 90L was dragged away by the TW, the two little vorts to 91L's NE are the TW and 90L
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2429. Levi32
Unfortunately, the ECMWF solution is very possible, as it usually is. It is still too far out to say, but the models are laying out the possibilities and the concern is that the GFS continues to underestimate the ridging near the eastern US because of its poor job on the MJO, and the ECMWF once it locks on usually has the right idea. Remember it was farthest south on Alex and ended up dead on.
Member Since: November 24, 2005 Posts: 635 Comments: 26547
2428. xcool
"0
Member Since: September 26, 2009 Posts: 2 Comments: 15620
2427. JavPR
Quoting JLPR2:
I think I'll go buy some batteries tomorrow, just to be safe. :)

i was thinking the same thing...but then again everytime I mention here at home that we should begin preparations so early they look at me like if I was a wishcaster....maybe they've been looking at this blogs LOL
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2426. Levi32
Quoting JLPR2:
Now I get it, this is why the NHC named this 91L


Its a new area of vorticity, the vorticity related to old 90L is at 11N 31W
91L is farther to the west and south.


No 11N 31W would be more associated with the incoming wave from behind. I've also noticed errors in the CIMSS vorticity analysis today because of all the convection (satellites can't see the low-level clouds) so those maps can't be trusted down to the detail. It's the same low as 90L. The only reason it's 91L is because they deactivated 90L and then had to re-designate it because the system still wants to develop.
Member Since: November 24, 2005 Posts: 635 Comments: 26547
2425. xcool
hmm
Member Since: September 26, 2009 Posts: 2 Comments: 15620
Quoting Levi32:
0z ECMWF shows a track through the Florida straights (very close to south Florida) and into the Gulf of Mexico. This would be a pretty bad hurricane should it take this path:

0z ECMWF 240 hours:



Yeah. you got that right.

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2423. JLPR2
Now I get it, this is why the NHC named this 91L


Its a new area of vorticity, the vorticity related to old 90L is at 11N 31W
91L is farther to the west and south.
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2422. Levi32
0z ECMWF shows a track through the Florida straights (very close to south Florida) and into the Gulf of Mexico. This would be a pretty bad hurricane should it take this path:

0z ECMWF 240 hours:

Member Since: November 24, 2005 Posts: 635 Comments: 26547
2421. JLPR2
I think I'll go buy some batteries tomorrow, just to be safe. :)
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2420. will45
Levi if you will take a look at the GFS 0Z run under sealevel pressure and the ridging looks stronger
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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.