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Pakistan monsoon floods kill at least 800

By: Dr. Jeff Masters, 5:56 PM GMT on July 31, 2010

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


The views of the author are his/her own and do not necessarily represent the position of The Weather Company or its parent, IBM.

Reader Comments

Quoting Zegama:
Albeit the intensity forecasts have been known not to be up to par but, I am surprised to see that the expectations for 90L are so low at 120hrs.

There is going to be a TUTT low involved down the line. The SHIPS is GFS based and could be showing some negative influence. Last nights ECMWF however, painted a different picture with a more positive influence of the TUTT.
Crown weather's write up - got my attention!!

Crown Weather
New Blog
3004. aquak9
TropicAddict- yes I think we all read CrownWeather. Thanks for giving credit where it's due. He runs an excellent site for free. Any support given to him is greatly appreciated.

sigh...got a nastygram form the homeowners assoc...gotta buy and lay some sod today. Good weight loss plan, I suppose.
3005. pottery
Well, I am out ........
Got to go and wade through the garden, and follow some Instructions from the Head Gardener!
Quoting bajelayman2:
Doubt 91L go north, it is too low too close to the Antilles. This is around where Ivan generated, even if he was a bit stronger at this time.

My expectation is via middle Atilles, into Caribbean sea.
you cant say just cause Ivan formed there and did this that this system, whatever it turns out to be, will follow suit...you would have to have the same conditions in place through its travels which near impossible to predict and not very likely.
Quoting stormwatcherCI:
Not add, subtract. 1800Z is 1400 DST or 1300 EST.

I thought add sounded wrong since we are West of the time line...
Quoting Zegama:

Good Morning. I'm here in Royal Palm Beach. Just waiting for it to pop out if the ITCZ.

Ha! I'm your neighbor just over in the acreage.
Quoting stormwatcherCI:
Flaring up this morning too. What do you think about 91L ?

I think 91L will be a Caribbean Cruiser, storms that form at that lattitude usually don't track north of Cuba, usually they track to Belize or after reaching the NW Caribbean curve and head toward the Gulf Coast.
Quoting aquak9:
pottery, Aussi, gambler, D'fly (where's Ike? I gotta add him in too) ya'lls just about the sweetest thing to lay eyes on...

and Bord...

We got some sweet young thangs joining our crew here too. Newbies they might be but they sure add a bit of shugah to my eyes.

CyclonicVoyage! how eloquent. CRAP. That just about sums it up.

oh, how am i behind pot on this? I am much younger and more handsome than him. hahaha

I think if i went outside i would get blown away, blowin' a gale outside. must be snowing on the Blue Mountains for sure.
Quoting breald:
It looks like for the first time I will have to start putting some people on ignore.

Alaina, I believe you are here to learn about the weather as am I.

Ho77, judging by your picture, you are on here to see how many idiotic men will drool all over you. And they do without even knowing if you are really a girl or a boy.

Quoting aquak9:
breald- that's one good way to get your questions answered around here, is to have a really hot avatar.

I tried using a thermometer reading at 104º for an avatar, but it didn't work for me...maybe some cayenne peppers would work, hahahaha

why do some of you have to be so rude? I have plenty of pics to prove this is me and QUESTION if I wasnt here to learn and just wanted men to drool over me why would I come here? why wouldnt I go to a dating blog or something? I love weather always have and recently found this site/blog and was a dream come true... I dont care what you think but why so rude? I have not said or done that to a single person on here...
3013. amd
Quoting Zegama:
Albeit the intensity forecasts have been known not to be up to par but, I am surprised to see that the expectations for 91L are so low at 120hrs.

91L will have to clear the TUTT that is typically located around 20 N 60 W first. That is the reason why SHIPS shows shear at 30 knots and 25 knots at the end of its forecast respectively. That will keep 91L within check in days 4 and 5.

After day 5, however, if 91L is sufficiently north of Hispanola to avoid inflow problems, then 91L can really begin to strengthen (As shown on the latest run of the EURO).
Quoting earthlydragonfly:

Im in Florida. so 5 hours it is.. Thanks

Fla is on DST so the diff is 4 until first sat in Nov then back to 5.
Quoting pottery:

Who "we" are tired of hot and dry?? LOL
Down here there is mildew sprouting from my armpits........

We is the east coast of central and north Florida who desperately need our afternoon showers back! The heat indexes of 108-110 every day are taking a toll...
Quoting stormpetrol:

I think 91L will be a Caribbean Cruiser, storms that form at that lattitude usually don't track north of Cuba, usually they track to Belize or after reaching the NW Caribbean curve and head toward the Gulf Coast.

Well, I hope you're wrong about your musings. I don't know what to think about where it will go, because it is a crap shoot this far out (can I say that?) Not that Haiti could use any more problems, but nobody in Cuba ever complains when a hurricane goes over it. (anyone here from Cuba?) Then a nice little gusher for SW FL, they could use the rain and since most people moved away from there when the economy went belly up, (and the rest are staying to pay the taxes, that went sky-high in 05)there will be plenty of empty houses to move into if yours gets blown away. Ya, always gotta keep a positive atitude about these things. But keep the TDs TSs and Hs away from the Yucatan until I get a new starter for my truck. Thanks for your cooperation. Feel free to come visit (by plane) State Dept says don't drive. But on the plus side, cheap Mexican beer is pretty good and is better than natty ice. (community service message)
3017. smuldy
3018. hydrus
Quoting pottery:

Sounds like you walk all over the poor guy.
Good Morning Pott. Looks like a major hurricane in the works.
looking likely we'll have colin tomorrow according to the latest intesity model runs!!!!
3020. docrod
Quoting pottery:
Well, I am out ........
Got to go and wade through the garden, and follow some Instructions from the Head Gardener!

Hi hear you - I've got two more trees to top (trim down to a level where they will not crash into the house) - good eve