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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2720. java162
i cant believe TWC is that slow..... in their recent update they still said it had a medium chance of development!!!!
Member Since: Posts: Comments:
Quoting StormW:
Greetings,
I see we have 91L. If I don't have one out by this afternoon, I'll have a synopsis on 91L late tonight.



morning sir, Looking forward to your synopsis (as always)!!
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Good morning, Storm.
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Quoting HaboobsRsweet:
My disclaimer...Everyone should not jump on the models with 91L today. Give them 24hours to lock onto the storm. Save all the model talk until tomorrow because the track that it spits out today will be way way off. Thanks.


Yup.
Member Since: July 8, 2005 Posts: 259 Comments: 24484
Looks like the main convection is trying to pull together.

Member Since: July 7, 2010 Posts: 4 Comments: 203
My disclaimer...Everyone should not jump on the models with 91L today. Give them 24hours to lock onto the storm. Save all the model talk until tomorrow because the track that it spits out today will be way way off. Thanks.
Member Since: Posts: Comments:
Quoting GainesvilleGator:
Good morning 91L. Too bad we don't have a five day forecast out yet. Will this stay low enough to avoid all that dry air? So far so good.


Dry air probably won't be a problem.
Member Since: July 8, 2005 Posts: 259 Comments: 24484
Quoting WeekiWacheeWoman:

North of Tampa by about 45 minutes.


East of you. Howdy neighbor!
Member Since: Posts: Comments:
Morning!
Finally got her designated huh? Its gonna be a long week.
How's everyone feeling?
Member Since: August 2, 2006 Posts: 0 Comments: 1240
2708. IKE
Quoting WeatherNerdPR:

91L is one SLOW runner.


Should pick up some speed in the next 48 hours. Maybe it'll fizzle out and defy all of the models. Seems unlikely though + it's August now.
Member Since: June 9, 2005 Posts: 23 Comments: 37860
Good morning 91L. Too bad we don't have a five day forecast out yet. Will this stay low enough to avoid all that dry air? So far so good.
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2706. IKE
Quoting WeekiWacheeWoman:

North of Tampa by about 45 minutes.


Go Rays. Win the series!
Member Since: June 9, 2005 Posts: 23 Comments: 37860
Quoting WeatherNerdPR:
Good morning. I see we have 91L. Wow, 60%. Who knew?


I figured it was coming.
Member Since: July 8, 2005 Posts: 259 Comments: 24484
2704. breald
Morning All!! I see we have invest 91.
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Quoting IKE:


Somewhere in Florida?

North of Tampa by about 45 minutes.
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2702. IKE
Quoting weatherwart:


Mermaids, dinosaurs and bears, oh my! Where else but Florida? lol


LOL.

System appears to be moving slowly just north of west to me.
Member Since: June 9, 2005 Posts: 23 Comments: 37860
Quoting Becca36:
Good morning all! I see I have a nice day of invest watching ahead of me today.


morning Becca! :)
Member Since: Posts: Comments:
Quoting IKE:


Looks that way.

What I hate about tropical systems....NEARLY STATIONARY LOW PRESSURE SYSTEM and...MOVES GENERALLY WESTWARD AT 5 TO 10 MPH

Move!

91L is one SLOW runner.
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2699. WxLogic
Quoting kmanislander:
Good morning all

Track and intensity forecasts spit out by models for 91L this early in the game should be taken with a grain of salt. In particular, the track forecasts are developed based upon how quickly each model thinks a closed low will form and how strong it will become. If you make a significant change in any of the major assumptions you get a big swing in the model run.

91L is nearing 40W and if it passes that without having made a defined move to the WNW a track N of the Leewards becomes a close call IMO unless it deepens very quickly.








I surely agree... the longer it takes to break off the ITCZ the greater the delay for that northerly component to realize early and therefore a greater threat to the Greater Antilles if it manages to organize further.
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Quoting weatherwart:


Mermaids, dinosaurs and bears, oh my! Where else but Florida? lol
sounds like a normal day in key west, nothing suprises me here anymore
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Quoting IKE:


Somewhere in Florida?


Mermaids, dinosaurs and bears, oh my! Where else but Florida? lol
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2696. Becca36
Good morning all! I see I have a nice day of invest watching ahead of me today.
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Hawaii could be in for a storm
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Good morning. I see we have 91L. Wow, 60%. Who knew?
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Quoting gulfcoastdweller:


oh hush!! lol, they are calling for a heat index of between 115 to 120 today on the Miss Gulf Coast
.........morning/evening Aussie

your in summer and i'm in winter, sucks to be me,,, i love summer.
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Morning, Kman. Jet lag all gone?

Agreed, until we have a closed low, everything is tentative. It's interesting to speculate, but it's a watch and wait game now.
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Quoting msgambler:
morning ho77yw00d


MORNING...HOW ARE YOU?
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2690. IKE
Quoting weatherwart:


Reminds me of mermaids and U.S. 19, dinosaur gas stations and bear crossings.


Somewhere in Florida?
Member Since: June 9, 2005 Posts: 23 Comments: 37860
Quoting IKE:
60% it is....

TROPICAL WEATHER OUTLOOK
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
800 AM EDT SUN AUG 1 2010

FOR THE NORTH ATLANTIC...CARIBBEAN SEA AND THE GULF OF MEXICO...

A NEARLY STATIONARY LOW PRESSURE SYSTEM LOCATED ABOUT 850 MILES
WEST-SOUTHWEST OF THE CAPE VERDE ISLANDS IS PRODUCING NUMEROUS
SHOWERS AND THUNDERSTORMS. THIS ACTIVITY HAS BECOME BETTER
ORGANIZED THIS MORNING AND CONDITIONS APPEAR CONDUCIVE FOR
DEVELOPMENT OF A TROPICAL DEPRESSION OVER THE NEXT DAY OR SO AS THE
DISTURBANCE MOVES GENERALLY WESTWARD AT 5 TO 10 MPH. THERE IS A
HIGH CHANCE...60 PERCENT...OF TROPICAL CYCLONE FORMATION DURING THE
NEXT 48 HOURS.

A WESTWARD-MOVING TROPICAL WAVE IS PRODUCING SCATTERED SHOWERS AND
THUNDERSTORMS OVER THE SOUTHWESTERN CARIBBEAN SEA. HOWEVER...THIS
ACTIVITY REMAINS SOMEWHAT DISORGANIZED AND UPPER-LEVEL WINDS ARE
CURRENTLY NOT CONDUCIVE FOR ANY SIGNIFICANT DEVELOPMENT BEFORE THE
DISTURBANCE MOVES INTO CENTRAL AMERICA IN THE NEXT DAY OR TWO.
THERE IS A LOW CHANCE...10 PERCENT...OF THIS SYSTEM BECOMING A
TROPICAL CYCLONE DURING THE NEXT 48 HOURS.

ELSEWHERE...TROPICAL CYCLONE FORMATION IS NOT EXPECTED DURING THE
NEXT 48 HOURS.

$$
FORECASTER STEWART/KIMBERLAIN

Mine hasn't ticked over yet,,, still got 40% on 91L. what's with that???

yes i did a refresh.
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2686. IKE
Quoting gulfcoastdweller:


so if it gets stronger it goes north, stays weaker goes south to the Caribb?


Looks that way.

What I hate about tropical systems....NEARLY STATIONARY LOW PRESSURE SYSTEM and...MOVES GENERALLY WESTWARD AT 5 TO 10 MPH

Move!
Member Since: June 9, 2005 Posts: 23 Comments: 37860
Quoting IKE:
WeekiWacheeWoman:

Your screen name reminds me of this song...Link

<<< smiling... one of my favorite songs. Ironically my screen name used to be WeekiWitchyWoman, but I had to change it because people kept asking if I practiced Wicca. LOL.
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2684. hulakai
91L is still pretty South. NOAA's historical tool reveals only two storms in the area of 91L. Dolly in 2002 fizzled as a fish and Fran in 1990 hit N. Venezuela as a TS. If 91L gains latitude, with everything else in place it will be interesting to to see how the negative JMO will come into play.
Member Since: Posts: Comments:
Good morning all

Track and intensity forecasts spit out by models for 91L this early in the game should be taken with a grain of salt. In particular, the track forecasts are developed based upon how quickly each model thinks a closed low will form and how strong it will become. If you make a significant change in any of the major assumptions you get a big swing in the model run.

91L is nearing 40W and if it passes that without having made a defined move to the WNW a track N of the Leewards becomes a close call IMO unless it deepens very quickly.






Member Since: Posts: Comments:
A NEARLY STATIONARY LOW PRESSURE SYSTEM LOCATED ABOUT 850 MILES
WEST-SOUTHWEST OF THE CAPE VERDE ISLANDS IS PRODUCING NUMEROUS
SHOWERS AND THUNDERSTORMS. THIS ACTIVITY HAS BECOME BETTER
ORGANIZED THIS MORNING AND CONDITIONS APPEAR CONDUCIVE FOR
DEVELOPMENT OF A TROPICAL DEPRESSION OVER THE NEXT DAY OR SO AS THE
DISTURBANCE MOVES GENERALLY WESTWARD AT 5 TO 10 MPH. THERE IS A
HIGH CHANCE...60 PERCENT...OF TROPICAL CYCLONE FORMATION DURING THE
NEXT 48 HOURS.
Member Since: July 8, 2005 Posts: 259 Comments: 24484
Quoting IKE:
WeekiWacheeWoman:

Your screen name reminds me of this song...Link


Reminds me of mermaids and U.S. 19, dinosaur gas stations and bear crossings.
Member Since: Posts: Comments:
RED ALERT 91L 60%.
Member Since: July 8, 2005 Posts: 259 Comments: 24484
Quoting Hardcoreweather2010:
Shouldn't this be the artist formerly known as 90L?

that's what I thought earlier but i was made aware 90L became entrained into this secondary wave. Hence we have 91L.
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2677. smuldy
That HP Ridge diagram from yesterday isn't accounting for the forecast model's take on the Mid Atlantic Ridge over Bermuda, I hope it's right and I'm wrong though.
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60% on 91L
Member Since: Posts: Comments:
2675. IKE
60% it is....

TROPICAL WEATHER OUTLOOK
NWS TPC/NATIONAL HURRICANE CENTER MIAMI FL
800 AM EDT SUN AUG 1 2010

FOR THE NORTH ATLANTIC...CARIBBEAN SEA AND THE GULF OF MEXICO...

A NEARLY STATIONARY LOW PRESSURE SYSTEM LOCATED ABOUT 850 MILES
WEST-SOUTHWEST OF THE CAPE VERDE ISLANDS IS PRODUCING NUMEROUS
SHOWERS AND THUNDERSTORMS. THIS ACTIVITY HAS BECOME BETTER
ORGANIZED THIS MORNING AND CONDITIONS APPEAR CONDUCIVE FOR
DEVELOPMENT OF A TROPICAL DEPRESSION OVER THE NEXT DAY OR SO AS THE
DISTURBANCE MOVES GENERALLY WESTWARD AT 5 TO 10 MPH. THERE IS A
HIGH CHANCE...60 PERCENT...OF TROPICAL CYCLONE FORMATION DURING THE
NEXT 48 HOURS.

A WESTWARD-MOVING TROPICAL WAVE IS PRODUCING SCATTERED SHOWERS AND
THUNDERSTORMS OVER THE SOUTHWESTERN CARIBBEAN SEA. HOWEVER...THIS
ACTIVITY REMAINS SOMEWHAT DISORGANIZED AND UPPER-LEVEL WINDS ARE
CURRENTLY NOT CONDUCIVE FOR ANY SIGNIFICANT DEVELOPMENT BEFORE THE
DISTURBANCE MOVES INTO CENTRAL AMERICA IN THE NEXT DAY OR TWO.
THERE IS A LOW CHANCE...10 PERCENT...OF THIS SYSTEM BECOMING A
TROPICAL CYCLONE DURING THE NEXT 48 HOURS.

ELSEWHERE...TROPICAL CYCLONE FORMATION IS NOT EXPECTED DURING THE
NEXT 48 HOURS.

$$
FORECASTER STEWART/KIMBERLAIN
Member Since: June 9, 2005 Posts: 23 Comments: 37860
Quoting texwarhawk:
Sunny and hot, with a high near 100. Heat index values as high as 104. Southwest wind around 5 mph

Current Humidity- 94%

Link


Yeah icky to your east too. This was earlier.

.PREV DISCUSSION... /ISSUED 330 AM CDT SUN AUG 1 2010/

..VERY HOT AND HUMID CONDITIONS TO CONTINUE TODAY...

DISCUSSION...
UPPER LEVEL RIDGE OVER THE SOUTHERN UNITED STATES WILL BE THE
MAIN WEATHER PLAYER FOR THE UP-COMING WEEK.

HUMID CONDITIONS REMAIN IN PLACE TONIGHT AND AS OF 3 AM CDT...DEW
POINTS STILL IN THE MID 70S TO LOWER 80S WITH HEAT INDEX VALUES
STILL RUNNING FROM 85 TO 95
Member Since: Posts: Comments:
Quoting ho77yw00d:


HIIIIIIIIIIIIIIIIIIIIIIII...

Good evening all. Sydney had a very beautiful day for middle of winter. got to 69.8F @15:00 about 20mins later a cold change came through and the temps have quickly fallen to 51.8F right now. For once i didn't feel cold even though it was only for a few hours.
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Quoting mcluvincane:


Worst nightmare if u ask me


It can be that too.
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2670. IKE
WeekiWacheeWoman:

Your screen name reminds me of this song...Link
Member Since: June 9, 2005 Posts: 23 Comments: 37860

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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.