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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1419. Levi32
Quoting YouCaneDoIt:
StormW, are there any sites or links to possible forecast tracks for this system?


Member Since: November 24, 2005 Posts: 628 Comments: 26452
1417. bappit
CIMSS has three pouches or invest areas on its PREDICT CIMSS Support Page.

The TCTrak pages for the two eastern Atlantic entities appears to show dry air invading the circulations.

Edit: not for the 90L entity. At least not yet. If it gains latitude the dry air is waiting for it though.







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1415. Levi32
You can see how this is really just the ITCZ in here, but it stands out as an abnormally large buildup of heat, and such things can and do develop in this kind of a situation. Remember that the pattern is getting more favorable in the eastern Atlantic as the weeks go by. Possibilities for mischief out here by this time were warned about for the last couple weeks.

Member Since: November 24, 2005 Posts: 628 Comments: 26452
StormW, are there any sites or links to possible forecast tracks for this system?
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Quoting weathermanwannabe:
Happy Hunting Folks......Lightenng too close to the house...........Se Yall Tommorow.


Wow! Y'all are abut to be rocked. Take care.
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Quoting CybrTeddy:


Felix in 2007.

Not according to the postseason report:

Link
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1410. Hhunter
Link
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Its got to come up 4 degrees........
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1407. Hhunter
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Quoting Hhunter:


yikes..

That ball of convection over the Bahamas has migrated over SC, GA and N FL. MAN, they're getting SLAMMED.

Looks like someone has poured 105 super-test high octane fuel on the ITCZ from the W coast of Africa, out to about 40W latitude.
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"C"
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Happy Hunting Folks......Lightenng too close to the house...........Se Yall Tommorow.
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I'll say C.
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Quoting StormW:


Go back to the IR2 Loop...9.5N;35.5W


You really think that will blow up?

Give
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Quoting TropicalAnalystwx13:
Poll time!

Question: At 2 AM tomorrow morning, what will the National Hurricane Center give Ex-90L in terms of percentages?

A. 30% or lower
B. 40%
C. 50%
D. 60% or higher

No other letters, numbers, or symbols!!!

C
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1400. Levi32
The center position is hard to pinpoint because we have the broad surface low located just south of what appears to be a mid-level circulation. With all the convection going off, it will be hard to see the real center for a while.
Member Since: November 24, 2005 Posts: 628 Comments: 26452
Quoting TropicalAnalystwx13:
Poll time!

Question: At 2 AM tomorrow morning, what will the National Hurricane Center give Ex-90L in terms of percentages?

A. 30% or lower
B. 40%
C. 50%
D. 60% or higher

No other letters, numbers, or symbols!!!
If convection continues to organize and "pop" until 2AM EDT I would think they would put it at 50% or "C".
Member Since: September 2, 2009 Posts: 130 Comments: 21032
Quoting StSimonsIslandGAGuy:
When was the last time we had a tropical cyclone form in the Atlantic from a disturbance in the ITCZ that was not a tropical wave?


Felix in 2007.
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If it continues organizing: C.
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1396. Hhunter


yikes..
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I sort of like that no models are being run.

First, I believe most agree that model tracks are unreliable without a defined circulation location for the initialization point.

Second, it cuts down on the amount of model-mayhem casting I have to read here, and brings to the forefront those with real forecasting abilities.
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Quoting TropicalAnalystwx13:
Poll time!

Question: At 2 AM tomorrow morning, what will the National Hurricane Center give Ex-90L in terms of percentages?

A. 30% or lower
B. 40%
C. 50%
D. 60% or higher

No other letters, numbers, or symbols!!!

I'll go with C.
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Quoting StormW:


Go back to the IR2 Loop...9.5N;35.5W
I'm looking at 8.5N 36.1W.
Member Since: September 2, 2009 Posts: 130 Comments: 21032
1391. leo305
So guys, what are the long termmodels saying about the track of this area of interest in the central atlantic? An out to sea storm or a storm caught by the ridge in the south east after getting pulled into the bahamas? Or what?
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Quoting weatherwart:


Strange you mentioned that. I just now heard some thunder and looked at the local radar. We're going to get hit here pretty soon. We had a spectacular sunset, but it at the same time, the air was very heavy and wet and soupy looking off to the north.

Stay safe!


I am north of Tally closer to the GA border and am being hammered right now by strong lightening......Fully how this system sort-of formed at tail end of a frontal boundry but over land........Oh well; gonna keep an eye on where it goes........ :)
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1388. JLPR2
Quoting TropicalAnalystwx13:
Poll time!

Question: At 2 AM tomorrow morning, what will the National Hurricane Center give Ex-90L in terms of percentages?

A. 30% or lower
B. 40%
C. 50%
D. 60% or higher

No other letters, numbers, or symbols!!!


I'll wait till 12am to answer this XD
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Quoting StormW:


You betcha!


Storm-What's your future take on this system?
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Quoting TropicalAnalystwx13:
Poll time!

Question: At 2 AM tomorrow morning, what will the National Hurricane Center give Ex-90L in terms of percentages?

A. 30% or lower
B. 40%
C. 50%
D. 60% or higher

No other letters, numbers, or symbols!!!



D
Member Since: May 21, 2006 Posts: 5089 Comments: 114026
1385. Hhunter
getting warm in here
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Poll time!

Question: At 2 AM tomorrow morning, what will the National Hurricane Center give Ex-90L in terms of percentages?

A. 30% or lower
B. 40%
C. 50%
D. 60% or higher

No other letters, numbers, or symbols!!!
Member Since: July 6, 2010 Posts: 108 Comments: 30237
Quoting 1900hurricane:

Not the case in SETX, unfortunately... XP


Lol. That's why I was laughing. Sorry hi everybody. :)

dated: 20 min 35 sec ago
Clear
83 °F
Clear
Humidity: 93%
Dew Point: 81 °F
Wind: Calm
Wind Gust: 1.0 mph
Pressure: 29.85 in (Falling)
Heat Index: 96 °F
Visibility: 10.0 miles
UV: 0 out of 16
Pollen: 3.20 out of 12

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I shouldn't do it but can't help myself. How about we name one of those super canes George Bush maybe it can finish destroying what was left after the last one.
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Quoting weathermanwannabe:
Good Evening.....Just checking in from Tallahassee to report that the overland "low" over North Florida/South Georgia is really firing up come serious convection and t-storms this evening.........This thing would be a tropical storm by now if it were over water.


Strange you mentioned that. I just now heard some thunder and looked at the local radar. We're going to get hit here pretty soon. We had a spectacular sunset, but it at the same time, the air was very heavy and wet and soupy looking off to the north.

Stay safe!
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Quoting StormW:


You betcha!


Are you looking at the blob? I see no circulation.
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1374. JLPR2
Quoting MiamiHurricanes09:
Impressive convective burst. Is it likely that the broad low pressure area could relocate under it?


it looks like the east side is getting ready to fire up too, so what would happen if 90L ends up rising from the dead and developing, it would absorb the wave behind it right? Instead of the wave absorbing it.
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Quoting Levi32:


Perhaps. By that term I mean either a low that is starting to close off and nearing depression status, a TD, or a weak TS.

Interesting.
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1370. Levi32
Thunderstorm tops are getting nice and high especially with that blob on the east side of the broad low.

Member Since: November 24, 2005 Posts: 628 Comments: 26452

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About JeffMasters

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