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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2370. Levi32
Hold on to your hats....the ECMWF is back onboard with feeding back the low and developing it into a tropical cyclone in 144 hours:

Member Since: November 24, 2005 Posts: 635 Comments: 26661
2369. JLPR2
Quoting CyclonicVoyage:


US bound from there looking at the pressure modeled.


Considering PR is a territory of the US that sound accurate. XD

Now if you mean Conus, well... if it takes Georges route it could be in for some trouble with the mountains of the Greater Antilles
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2368. xcool
Levi32 YOU BEAT ME TO IT ;(
Member Since: September 26, 2009 Posts: 2 Comments: 15684
2367. xcool
. JLPR2 YEAH WEAK STORMS
Member Since: September 26, 2009 Posts: 2 Comments: 15684
AL, 91, 2010080106, , BEST, 0, 90N, 350W, 20, 1009, DB, 34, NEQ, 0, 0, 0, 0, 1010, 180, 50, 0, 0, L, 0, , 0, 0, INVEST
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2365. Levi32
Quoting scott39:
Wheres our Invest Levi?


What do you mean?
Member Since: November 24, 2005 Posts: 635 Comments: 26661
2364. will45
The intertropical convergence zone (ITCZ) is observed to undulate and at times break down into a series of tropical disturbances in several days. Some of these disturbances may develop into tropical cyclones and move to higher latitudes, while others dissipate, and the ITCZ may reform in the original region. It has been proposed that the ITCZ may break down because of its heating-induced potential vorticity (PV) anomalies. Here this process is examined in three-dimensional simulations using a primitive equation model. A simulation of the ITCZ in a background state of rest is compared to simulations in different background flows. The effect of different vertical structures of the prescribed heating is also examined.

From AMS Journal
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2363. xcool
Levi32 WHY WHY LOL
Member Since: September 26, 2009 Posts: 2 Comments: 15684
Quoting Levi32:
0z ECMWF 120 hours is in line with my track idea of the northern Antilles, and now develops the system a bit so far on the run:



US bound from there looking at the pressure modeled.
Member Since: January 30, 2010 Posts: 0 Comments: 3259
2361. scott39
Quoting Levi32:
0z ECMWF 120 hours is in line with my track idea of the northern Antilles, and now develops the system a bit so far on the run:

Wheres our Invest Levi?
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2360. Levi32
0z ECMWF 120 hours is in line with my track idea of the northern Antilles, and now develops the system a bit so far on the run:

Member Since: November 24, 2005 Posts: 635 Comments: 26661
2359. scott39
Its impressive looking ---- but it needs time to organize. As far as an Invest---who the blankety-- blank knows!
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2358. JLPR2
Quoting xcool:



96H


seems to be keeping it weak
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2357. xcool


48HR
Member Since: September 26, 2009 Posts: 2 Comments: 15684
2356. xcool
CyclonicVoyage .NO PROB ;)
Member Since: September 26, 2009 Posts: 2 Comments: 15684
2355. xcool



96H
Member Since: September 26, 2009 Posts: 2 Comments: 15684
Quoting xcool:
CyclonicVoyage OLD MAP 18Z.NOW 00Z


Pulled from the 2am NHC advisory, my fault.

Anyway, stuff doesn't change much way down there in 6 hours unless a tropical cyclone is about.
Member Since: January 30, 2010 Posts: 0 Comments: 3259
2352. xcool
ECMWF



Member Since: September 26, 2009 Posts: 2 Comments: 15684
2351. JLPR2
Quoting xcool:


It's a huge area of disturbed weather.
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2350. xcool
CyclonicVoyage OLD MAP 18Z.NOW 00Z
Member Since: September 26, 2009 Posts: 2 Comments: 15684
Quoting xcool:
CyclonicVoyage OLD


??
Member Since: January 30, 2010 Posts: 0 Comments: 3259
2348. xcool
Member Since: September 26, 2009 Posts: 2 Comments: 15684
2347. JLPR2
Quoting will45:
Storms have developed in the ITCZ before


Of course, it just needs to dominate the ITCZ, but it needs to grow stronger for that.
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2346. xcool
XXXX90L GET OUT OF ITCZ
Member Since: September 26, 2009 Posts: 2 Comments: 15684
We'll see new models tomorrow.

NHC hasn't been doing much updating overnight with 90L. 91L should be declared in the morning.
Member Since: January 30, 2010 Posts: 0 Comments: 3259
2344. JLPR2
Quoting SouthALWX:

Thats difficult to pull off, but since the ITCZ is broken, it is not impossible especially since it could reform (the ITCZ) further south.


Yes, its difficult, but I guess all we can do is watch. :)
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2343. xcool


UPDATE
Member Since: September 26, 2009 Posts: 2 Comments: 15684
2342. will45
Storms have developed in the ITCZ before
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2341. xcool
CyclonicVoyage OLD
Member Since: September 26, 2009 Posts: 2 Comments: 15684
2339. SLU
WOW. Tropical Cyclone Danger Area.
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2338. xcool
Member Since: September 26, 2009 Posts: 2 Comments: 15684
latest surface map

Member Since: January 30, 2010 Posts: 0 Comments: 3259
Quoting JLPR2:


Seems reasonable but if the convection continues it might develop while still attached to the ITCZ.

Thats difficult to pull off, but since the ITCZ is broken, it is not impossible especially since it could reform (the ITCZ) further south.
Member Since: August 27, 2008 Posts: 0 Comments: 1497
2335. xcool



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2334. scott39
TD by Monday PM. IMO
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2332. EricSFL
Quoting btwntx08:
he doesnt deserve nada lol still couldve been fake


But it was not.
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2331. JLPR2
Quoting CyclonicVoyage:


ITCZ is still hovering around 10N, they may be waiting to see it break to the WNW and gain some latitude over the ITCZ.


Seems reasonable but if the convection continues it might develop while still attached to the ITCZ.
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Quoting btwntx08:
he doesnt deserve nada lol still couldve been fake

It was NOT a fake, It was identical. Even the elipses are perfect. Quit trolling.
Member Since: August 27, 2008 Posts: 0 Comments: 1497
2329. xcool
91L next get ready
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2328. xcool
;;;
Member Since: September 26, 2009 Posts: 2 Comments: 15684
2327. JLPR2
Quoting btwntx08:
he doesnt deserve nada lol still couldve been fake


you do need sleep XD
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Quoting CyclonicVoyage:


ITCZ is still hovering around 10N, they may be waiting to see it break to the WNW and gain some latitude over the ITCZ.

Exactly. +1 ... until this thing gains lat, it really wont do a whole lot ... no rush on the %, but it does need to be an invest.
Member Since: August 27, 2008 Posts: 0 Comments: 1497
2324. xcool
btwntx08 why 70%
Member Since: September 26, 2009 Posts: 2 Comments: 15684
40% is reasonable I think ... call me crazy but I think this thing will be slow to develop. No doubt it needs to be an Invest, though.
Member Since: August 27, 2008 Posts: 0 Comments: 1497
2322. scott39
Big---- AOI take time to organize!
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Quoting JLPR2:


I still cant believe no invest has been declared.


ITCZ is still hovering around 10N, they may be waiting to see it break to the WNW and gain some latitude over the ITCZ.
Member Since: January 30, 2010 Posts: 0 Comments: 3259

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About

Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.