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 stormhank:
When will that area marked 40% be re classified??

I would think most likely early tommorrow moring if it holds together
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WeathrfanPr: That is correct. It is at about 9.3N and 93W now and has lifted north. There is some strong convection southeast of the center. The wave axis is around 27W and 15N.
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1218. bappit
Quoting bappit:
Interesting comment from footnote 42 in appendix C (LOL):

Large-amplitude easterly waves, that is, with large meridional extent, may be ineffective for TC genesis owing to the latter reason [that they draw air in from the north].

So we've seen some large waves this season which all went pffffft.


Hmmmmm, could warm SST's lead to larger waves which in turn lead to less favorable conditions for tropical storm development?
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I feel sorry for the bahamas and florida this year. That's a fact not a opinion.
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I think you got it dead to rights Keeper.
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Oh by the way Levi.....Circular Circulation? LOL
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When will that area marked 40% be re classified??
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1212. KEEPEROFTHEGATE (Mod)

NMFC Norfolk Tropical Feed
No Active Tropical Warnings in the Atlantic, Caribbean, or Gulf of Mexico
By Maritime.CDO@navy.mil (NMFC CDO) from Naval Maritime Forecast Center Norfolk Virginia. Published on .

As of Sun 01 Aug 2010 00:00:01Z
2010 Storms
All Active Year

Atlantic
NONE
East Pacific
97E.INVEST
Central Pacific
92C.INVEST
West Pacific
95W.INVEST
Indian Ocean
NONE
Southern Hemisphere
NONE
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Evening granny
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Quoting Levi32:


That would be the elongated trough extending out from the main, broad low center located near 36W. It's not a well-defined, circular circulation, but rather an elongated one which is typical of a system embedded within the ITCZ.


Thanks Levi, been seeing that for a while. Thought you might seen a closed circ. that I missed.
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Good evening Gambler,Xcool and all my WU friends.Boy I go to work and when I get home,WOWWW!!!!The tropics are busting out loud.
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Blog Tropical Storm in the Making?Link

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Quoting msgambler:
When did we get 91L. I didn't think it had a label yet. Where was I?
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1205. palmpt
Quoting cirrocumulus:
Kerry Emmanuel of MIT wrote about the maximum potential intensity deepening to below 800 mb by the end of the century. He is very very smart and informed about tropical cyclone physics. It's hard for me to see that really happening however. But who knows?

If we really do get hurricanes with central pressures in the high 700 mb range I want scarier names!

Hurricane Cobra
Hurricane Sabretooth

Things like that.


Clever!
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Quoting cirrocumulus:
Kerry Emmanuel of MIT wrote about the maximum potential intensity deepening to below 800 mb by the end of the century. He is very very smart and informed about tropical cyclone physics. It's hard for me to see that really happening however. But who knows?

If we really do get hurricanes with central pressures in the high 700 mb range I want scarier names!

Hurricane Cobra
Hurricane Sabretooth

Things like that.
I'd like Hurricane P90X! It's killing me right now.
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1203. JLPR2
Quoting KEEPEROFTHEGATE:
AOI/XX/XL
MARK
8.4N/35.7W


Looks like the blob of convection is the point of interaction between 90L and the TW.
Member Since: September 4, 2007 Posts: 7 Comments: 8747
I think that the main Vort is located near 9.3n and 35.5w
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1201. KEEPEROFTHEGATE (Mod)


CENTRE FIX 8.4N/35.7W
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Quoting KEEPEROFTHEGATE:
AOI/XX/XL
MARK
8.4N/35.7W


Convection looks to be consolodating near the center.
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...SPECIAL FEATURE...
A TROPICAL WAVE IS SW OF THE CAPE VERDE ISLANDS ALONG 27W
SOUTH OF 15N. THIS WAVE IS EMBEDDED WITHIN AN AREA OF A HIGH
AMPLITUDE MOISTURE MAXIMUM. A WELL DEFINED LOW TO MID LEVEL
CYCLONIC FLOW SURROUNDS THE WAVE AXIS EVIDENT ON INFRA RED
SATELLITE DATA. WHILE AMPLE MOISTURE IS NOTED IN THE LOW
LEVELS...A SAHARAN AIR LAYER IS PREVENTING ANY SIGNIFICANT
CONVECTION IN ASSOCIATION WITH THE WAVE. THEREFORE...MOST OF THE
CONVECTION NEAR BY THIS SYSTEM IS DUE TO INTERACTION WITH AN
ELONGATED AREA OF LOW PRESSURE EMBEDDED IN THE ITCZ. ALTHOUGH
THIS ENTIRE AREA OF DISTURBED WEATHER REMAINS
DISORGANIZED...SHOWER AND THUNDERSTORM ACTIVITY HAS INCREASED
DURING THE DAY. CONDITIONS APPEAR FAVORABLE FOR SOME SLOW
DEVELOPMENT AS THE DISTURBANCE MOVES SLOWLY WESTWARD...AND THERE
IS A MEDIUM CHANCE OF TROPICAL CYCLONE FORMATION DURING THE NEXT
48 HOURS.
Member Since: September 30, 2005 Posts: 0 Comments: 1606
The following is excerpted from Emanuel%u2019s BR book, What We Know About Climate Change.


Projections based on climate models suggest that the globe will continue to warm another 3 to 7F over the next century. This is similar to the temperature change one could experience by moving, say, from Boston to Philadelphia. Moreover, the warming of already hot regions%u2014the tropics%u2014is expected to be somewhat less, while the warming of cold regions like the arctic is projected to be more, a signal already discernable in global temperature measurements. Nighttime temperatures are increasing more rapidly than daytime warmth.

Is this really so bad? In all the negative publicity about global warming, it is easy to overlook the benefits: It will take less energy to heat buildings, previously infertile lands of high latitudes will start producing crops, and there will be less suffering from debilitating cold waves. Increased CO2 might also make crops grow faster. On the down side, there will be more frequent and more intense heat waves, air conditioning costs will rise, and previously fertile areas in the subtropics may become unarable. Sure, there will be winners and losers, but will the world really suffer in the net? Even if the changes we are bringing about are larger than the globe has experienced in the last few thousand years, they still do not amount to the big natural swings between ice ages and interglacial periods, and the earth and indeed human beings survived these.

But there are consequences of warming that we cannot take so lightly. During the peak of the last ice age, sea level was some 400 feet lower than today%u2019s, since huge quantities of water were locked up in the great continental ice sheets. As polar regions warm, it is possible that portions of the Greenland and Antarctic ice sheets will melt, increasing sea level. Highly detailed and accurate satellite-based measurements of the thickness of the Greenland ice show that it is actually increasing in the interior but thinning around the margins, and while there are also patterns of increase and decrease in Antarctic ice, it appears to be thinning on the whole. Meltwater from the surface of the Greenland ice sheet is making its way to the bottom of the ice, possibly allowing the ice to flow faster toward the sea. Our understanding of the physics of ice under pressure is poor, and it is thus difficult to predict how the ice will respond to warming. Were the entire Greenland ice cap to melt, sea level would increase by around 22 feet%u2014flooding many coastal regions including much of southern Florida and lower Manhattan.

My own work has shown that hurricanes are responding to warming sea surface temperatures faster than we originally expected, especially in the North Atlantic, where the total power output by tropical cyclones has increased by around 60 percent since the 1970s. The 2005 hurricane season was the most active in the 150 years of records, corresponding to record warmth of the tropical Atlantic. Hurricanes are far and away the worst natural disasters to affect the U.S. in economic terms. Katrina may cost us as much as $200 billion, and it has claimed at least 1,200 lives. Globally, tropical cyclones cause staggering loss of life and misery. Hurricane Mitch of 1998 killed over 10,000 people in Central America, and in 1970 a single storm took the lives of some 300,000 people in Bangladesh. Substantial changes in hurricane activity cannot be written off as mere climate perturbations to which we will easily adjust.

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1197. bappit
The appendices are more interesting than the paper. On page 5636:

A possibly significant role for hydrodynamically stable waves in this context is counter-intuitive: one might be tempted to think that large-scale instability implies a more vigorous sequence of events that would lead to genesis more readily than what might be triggered by a neutral or slowly decaying wave. But we must be willing to entertain less intuitive ideas in order to understand the possible preference for neutral or slowly decaying modes in TC genesis. (i) These modes are maintained by diabatic heating (H3) in addition to their “dry” maintenance (compact spectral content). (ii) Genesis is an interactive multi-scale process and not simply a consequence of moist hydrodynamic instability. If the quasi-mode configuration as described above favors mesoscale development, then it may actually be more favorable for genesis than a more vigorous unstable wave. Oddly enough, the fact that the instability paradigm in reality applies only to a minority of cases seems to support such counter-intuitive thinking.

Simplified, I think they are saying that less-vigorous systems may have an advantage over some waves that have vigorous convection. It reminds me of Humberto which formed rapidly from a system that was an invest--a weak invest at that--which was declassified a day or so before Humberto formed.





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Quoting StormSurgeon:


36 West? What are ya'll looking at? Am I missing something? 35 West?

I'm looking at this. It seems to me that your looking at the surface through rather than the low.
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1195. Levi32
Quoting StormSurgeon:


36 West? What are ya'll looking at? Am I missing something? 35 West?



That would be the elongated trough extending out from the main, broad low center located near 36W. It's not a well-defined, circular circulation, but rather an elongated one which is typical of a system embedded within the ITCZ.
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Quoting MiamiHurricanes09:
You got some good eyes Levi. If you wouldn't of mentioned it I wouldn't have noticed. 8.5N and 36.1W looks about right to me.


36 West? What are ya'll looking at? Am I missing something? 35 West?

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Quoting muddertracker:
I agree with all of that..40 is sneaking up on me fast, and I've never been happier in my life. I can only hope I'm still accomplishing things when I'm Eastwood's age!

So very true with regards to the great actor and one my favorites Clint Eastwood .I'll be 46 Nov 3 and still going strong, despite some health problems.
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Quoting cirrocumulus:
91L is starting to gain more convection as it pulls slightly northward from it's old position at 8.5. Now it's at 9.2 and 35.1W.
When did we get 91L. I didn't think it had a label yet. Where was I?
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Quoting Levi32:


Shutting down what, the Atlantic? No it won't, only the Pacific.


your video's explain all this... WOW LOL
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1190. Levi32
Quoting Tazmanian:



did t you said that if it gets too strong winds shear will start going up


Strong La Ninas can create easterly shear over the tropical Atlantic yes, but not this particular year. In fact we could use more easterlies than we currently have. This year the crash down into La Nina is one of the fastest on record, and this isn't giving it the time to drain the tropical Atlantic of any heat like a typical strong La Nina does, and thus there is still a lot of energy available and the effects of the La Nina are pretty much all positive for tropical activity in the Atlantic.
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1189. KEEPEROFTHEGATE (Mod)
AOI/XX/XL
MARK
8.4N/35.7W
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Quoting AllStar17:
STILL no invest.


I'm starting 2 get mad @ the NHC, first for declassifying the Invest, and now for not putting up an Invest. >:(
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Quoting AllStar17:
STILL no invest.
Probably around 8:30 if 90L gets reactivated.
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91L is starting to gain more convection as it pulls slightly northward from it's old position at 8.5. Now it's at 9.2 and 35.1W.
Member Since: September 30, 2005 Posts: 0 Comments: 1606
STILL no invest.
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Quoting thunderblogger:
How much longer is the ridge of high pressure going to hang around the GOM?

About 4-7 days minimum
Member Since: August 25, 2009 Posts: 20 Comments: 6785
T.D. in the
AM Tomorrow.
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Quoting stormpetrol:

I'll say "Make my day" liked the Clint Eastwood pic you posted earlier, He's 80 now, Father Time sure works on all of us, blessed are those that stick around for Father time to work on that's my motto, afriend of mine the other day told me he didn't like the idea of getting old, I told I didn't like the alternative, he asked well what's that I said Dying young, he bursted out laughing!
I agree with all of that..40 is sneaking up on me fast, and I've never been happier in my life. I can only hope I'm still accomplishing things when I'm Eastwood's age!
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1178. beell
Quoting aquak9:


you're right, they tag it with an L. Next number up, it'll be 91L. Don't think they'll re-use 90L.


I agree, H2OK9. x90L is now the wave along 50W.
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How much longer is the ridge of high pressure going to hang around the GOM?
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Quoting Filibuster:


Taz, La Nina does not shut down the Atlantic basin, OK?



UPDATE: My bad, he was talking about the Atlantic Basin. I'm sorry.

-Snowy
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The circulation appears to be much tighter now than earlier today.
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1174. Levi32
Quoting Tazmanian:
i hop La Nina dos not get too march strong or it will start shuting thing down this like they have had for the W PAC


Quoting Tazmanian:
. Levi32 plz look at commet 1157 thanks


Shutting down what, the Atlantic? No it won't, only the Pacific.
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Quoting weatherman12345:

dude, stop posting the same crap over and over again


ROFLAMO!
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Quoting MiamiHurricanes09:
Based on shortwave loops I would put circulation of ex-90L near 9.2N and 36.1W.


Good evening. So, how far away is that, 3-4,000 miles? I probably have time before I start filling the bathtub, right? ;-)
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Quoting Levi32:


If you look very closely at the low-level cloud structure you'll see that it's a little more south of that, closer to 8.5N.
You got some good eyes Levi. If you wouldn't of mentioned it I wouldn't have noticed. 8.5N and 36.1W looks about right to me.
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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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