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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Quoting ho77yw00d:
Thank you guys so much you are teaching me a lot and I am catching on so... Thank you if I knew how to put a image up on post I would send you guys a kiss... so here ya go muah lol back to weather Its so exciting!!!
LOL! You need to download Firefox preferably to post images.
Member Since: September 2, 2009 Posts: 130 Comments: 21372
You're welcome. How about Sasquatch, Lochness, and Great White during the Mayan calendar year.
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Quoting tropicaltank:
I concur. Do you think GOM or East coast?


East Coast, especially south of NC.
Member Since: July 6, 2010 Posts: 113 Comments: 34483
Quoting Levi32:


More like 8.5N, 36.5W if you're looking for the overall center of the broad low. There is an elongated trough extending ENE.


Hi Levi. What's it going to take for this broad low to become more consolidated? What has to happen? Thanks.
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Quoting cirrocumulus:
The intensity of hurricanes will continue to increase, though their frequency may dwindle.


Would I rather take my chances with five Cat 2 storms, or two Cat 5 storms? Hmmm. That's a little like asking whether I'd rather be shot multiple times with a BB gun, or just once with a sawed-off shotgun. Yikes...
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1312. bappit
Quoting bappit:
tropical depression: Although no formal definition can be found, a tropical depression-strength vortex is thought to exist when circular horizontal winds approach 30 knots and deep, persistent convection is well-organized by a putative closed circulation. It can be said that forecasters regard a proto-structure with features loosely resembling a mature hurricane as a good candidate for a “depression” – the more such features, the better. Their classification evidently guarantees (in all but a few instances) subsequent growth to a named tropical storm. It is not only the statistical narrowness of the tropical depression classification, but a physical threshold for instability leading to intensification, that is responsible for their success. In other words, “tropical depression” is a physically meaningful, albeit imprecisely defined, concept.

Interesting.

Going with the idea of a vortex that is likely to develop into a named system, the only thing to prevent calling 95L a tropical depression was its proximity to land. If it had had a little more runway, no doubt it would have taken off.
Member Since: May 18, 2006 Posts: 10 Comments: 6195
ASCAT shows a better organized system than the last pass it showed, at that time ex-90L just had a sharp wind shift now it shows a broad low trying to close off.
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Quoting TropicalAnalystwx13:
I give this system an 80% of developing into at least a TD by Wednesday.
I concur. Do you think GOM or East coast?
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Quoting bohonkweatherman:
I think we will have a tropical storm or hurricane by the middle of next week
Agreed.
Member Since: September 2, 2009 Posts: 130 Comments: 21372
1307. Levi32
Quoting tropicaltank:
We are at 9.6 north?


More like 8.5N, 36.5W if you're looking for the overall center of the broad low. There is an elongated trough extending ENE.
Member Since: November 24, 2005 Posts: 635 Comments: 26775
Quoting StormW:


Bad question


That kinda day huh? Went there 3 years ago, and never going back.
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1304. Levi32
Quoting ho77yw00d:
STORM AND LEVI THANKS now you said if you can get them to agree then watch out so up to now have they? if so then what?


They have not been in agreement on this system recently. For example, the ECMWF doesn't develop it and takes it farther south than the GFS right now. This is not surprising since the models are still not fully locked onto the system, as we are still dealing with an elongated area of low pressure that will be merging with another wave, so we can't expect a lot of consistency or agreement from the models at this point. Almost every one is showing a different solution right now. That's why we have to use good old common-sense forecasting right now, which we should always use anyway.
Member Since: November 24, 2005 Posts: 635 Comments: 26775
Have we ever gone from a non-invest to a TD?
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1302. JLPR2
Quoting StSimonsIslandGAGuy:


I posted a whole bunch of names like that hours ago on my blog.

Just mildly miffed that my post 247 was not given credit. And lifted word for word.


1900hurricane that is where I got Cobra from

But I got the rest on my own. Lots on my blog.


Well I must say that Hurricane Dracula sounds like a bad one. XD
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Quoting MiamiHurricanes09:
I would say it is the second most accurate model we have behind the Euro. Nrt will give you the link for the model verifications.


I didnt see you answered me.. THANKS!!!
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I give this system an 80% of developing into at least a TD by Wednesday.
Member Since: July 6, 2010 Posts: 113 Comments: 34483
Quoting StSimonsIslandGAGuy:


Cirrocumulus, that's very cool you like my hurricane names! But a little credit would be nice, since I posted this way back at comment 245 :)


I meant to quote you and Kerry Emmanuel! Here is more by Kerry.While the American public has been misinformed by a media obsessed with sensational debate, climate scientists developed a way forward that helps them to compare notes and test one another’s ideas and also creates a valuable communication channel. Called the Intergovernmental Panel on Climate Change, or IPCC, it produces a detailed summary of the state of the science every four years, with the next one due out in February 2007. Although far from perfect, the IPCC involves serious climate scientists from many countries and has largely withstood political attack and influence.

The IPCC reports are fairly candid about what we collectively know and where the uncertainties probably lie. In the first category are findings that are not in dispute, not even by les refusards:

• Concentrations of the greenhouse gases carbon dioxide, methane, ozone, and nitrous oxide are increasing owing to fossil-fuel consumption and biomass burning. Carbon dioxide has increased from its pre-industrial level of about 280 parts per million (ppmv) to about 380 ppmv today, an increase of about 35 percent. From ice-core records, it is evident that present levels of CO2 exceed those experienced by the planet at any time over at least the past 650,000 years.

• Concentrations of certain anthropogenic aerosols have also increased owing to industrial activity.

• The earth’s average surface temperature has increased by about 1.2°F in the past century, with most of the increase occurring from about 1920 to 1950, and again beginning around 1975. The year 2005 was the warmest in the instrumental record.

• Sea level has risen by about 2.7 inches over the past 40 years; of this, a little over an inch occurred during the past decade.

• The annual mean geographical extent of arctic sea ice has decreased by 15 to 20 percent since satellite measurements of this began in 1978.


In the second category are findings that most climate scientists agree with but are disputed by some:

• The global mean temperature is now greater than at any time in at least the past 500 to 1,000 years.

• Most of the global mean temperature variability is caused by four factors: variability of solar output, major volcanic eruptions, and anthropogenic sulfate aerosols and greenhouse gases.

• The dramatic rise in global mean temperature in the past 30 years is owing primarily to increasing greenhouse-gas concentrations and a leveling off or slight decline in sulfate aerosols.

• Unless measures are taken to reduce greenhouse-gas production, global mean temperature will continue to increase, about 2.5 to 9°F over the next century, depending on uncertainties and how much greenhouse gas is produced.

• As a result of the thermal expansion of sea water and the melting of polar ice caps, sea level will increase six to 16 inches over the next century,though the increase could be larger if large continental ice sheets become unstable.

• Rainfall will continue to become concentrated in increasingly heavy but less frequent events.

• The incidence, intensity, and duration of both floods and drought will increase.

• The intensity of hurricanes will continue to increase, though their frequency may dwindle.


All these projections depend, of course, on how much greenhouse gas is added to the atmosphere over the next century, and even if we could be certain about the changes, estimating their net effect on humanity is an enormously complex undertaking, pitting uncertain estimates of costs and benefits against the costs of curtailing greenhouse-gas emissions. But we are by no means certain about what kind of changes are in store, and we must be wary of climate surprises. Even if we believed that the projected climate changes would be mostly beneficial, we might be inclined to make sacrifices as an insurance policy against potentially harmful surprises.


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I think we will have a tropical storm or hurricane by the middle of next week
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We are at 9.6 north?
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1296. Zegama
Thanks for posting, Gordydonnut. I was trying to get it on here but, experiencing technical difficulties.
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STORM AND LEVI THANKS now you said if you can get them to agree then watch out so up to now have they? if so then what?
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.
Member Since: May 21, 2006 Posts: 5096 Comments: 116645
Im getting some good shots!! Not bad
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oops
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i think we may have TD 4 by monday
Member Since: May 21, 2006 Posts: 5096 Comments: 116645
Quoting ho77yw00d:
QUESTION how accurate is GFS?
I would say it is the second most accurate model we have behind the Euro. Nrt will give you the link for the model verifications.
Member Since: September 2, 2009 Posts: 130 Comments: 21372
Not Good
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1284. Levi32
Quoting ho77yw00d:
QUESTION how accurate is GFS?


Well let's put it this way....it has a lot of flaws but can sometimes be good in the tropics. Other times it can be downright awful. If you get the GFS and ECMWF agreeing on something though, you better watch out.
Member Since: November 24, 2005 Posts: 635 Comments: 26775
Quoting Levi32:
ASCAT pass just 90 minutes old shows a well-defined trough and associated wind shift with the tropical wave near 27W.



Elongated low open to the west.
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Quoting caneswatch:
Good evening Storm! How was the day in Busch Gardens?


Why would anyone want to be walking around Busch Gardens today? It was killer hot!
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Quoting Levi32:


The African Easterly Jet is just like any other jetstream. Think of our polar jetstream in the wintertime....a stronger jet results in larger waves within the jet.

The ITCZ farther north than normal is often correlated with a stronger AEJ and can be caused by a colder than normal Gulf of Guinea or a stronger than normal Indian Monsoon. The farther north position of the ITCZ contributes to larger waves because #1 it is again correlated with a stronger AEJ and #2 it sends more waves out over the Atlantic at a farther north latitude, where they get amplified down to where the Atlantic ITCZ and yet extend farther north into the dry airmass of the subtropical high.


I think this is a fair correlation.
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Good evening Storm.What do you think of the Entity?
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1276. bappit
Quoting Levi32:


They are correct that large waves extending far to the north end up embedded in dry air and entrain a stable airmass, which can prevent development in the eastern Atlantic, however, that makes them a big threat farther west because such waves can remain well-defined for a long time and then blow up convection when they encounter the TUTT near the Caribbean. Bonnie this year was the classic example of this. She was a massive, naked wave in the eastern Atlantic embedded in dry air to the north but then she blew up north of the Caribbean once she got west of 50-60W.

For a large wave, Bonnie was a small storm. Sure would be interesting to see what sort of cat's eye might have existed.

Yep, the TUTT. Not sure how that is treated in their theoretical debate over bottom-up and top-down. The TUTT enhances convection at the surface. Things seem upside down. Eggs laying chickens, so to speak.
Member Since: May 18, 2006 Posts: 10 Comments: 6195
Orca, looks like I am gonna need to borrow your stirrin' the pot smiley for Keeper. He is havin' a problem behavin'.
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Quoting StormW:
Back.


Hey man, go have a chat with Filiboober, or what ever he is.........
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Good evening Storm! How was the day in Busch Gardens?
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Quoting StSimonsIslandGAGuy:


Cirrocumulus, that's very cool you like my hurricane names! But a little credit would be nice, since I posted this way back at comment 245 :)

Typhoon Cobra
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1270. Zegama
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Dr. Masters co-founded wunderground in 1995. He flew with the NOAA Hurricane Hunters from 1986-1990. Co-blogging with him: Bob Henson, @bhensonweather

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