Pakistan's Katrina; 94L could develop in Gulf of Mexico

By: Dr. Jeff Masters , 3:23 PM GMT on August 10, 2010

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The monsoon season of 2010 continues to generate havoc in Asia, as lingering rains from the latest monsoon low continue to affect hard-hit Pakistan, China, and India. At least 702 are now reported dead and 1,042 are missing in China's Gansu province, due to torrential monsoon rains that triggered a deadly landslide and extreme flooding on Sunday. At least 137 died in floods and landslides in the neighboring Indian state of Kashmir over the weekend, with 500 people missing. Monsoon flooding and landslides have also killed at least 65 people in Afghanistan in the past two weeks. But no country has suffered more than Pakistan, where monsoon floods have destroyed huge portions of the nation's infrastructure and killed at least 1600 people. The number of people affected or needing assistance has been estimated to be as high as 13 million people--8% of the nation's population. The disaster is the worst natural disaster in Pakistan's history, and is rightfully being called "Pakistan's Katrina."


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.

Monsoons: a primer
In summer, the sun warms up land areas more strongly than ocean areas. This occurs because wind and ocean turbulence mix the ocean's absorbed heat into a "mixed layer" approximately 50 meters deep, whereas on land, the sun's heat penetrates at a slow rate to a limited depth. Furthermore, due to its molecular properties, water has the ability to absorb more heat than the solid materials that make up land. As a result of this summertime differential heating of land and ocean, a low pressure region featuring rising air develops over land areas. Moisture-laden ocean winds blow towards the low pressure region and are drawn upwards once over land. The rising air expands and cools, condensing its moisture into some of the heaviest rains on Earth--the monsoon. Monsoons operate via the same principle as the familiar summer afternoon sea breeze, but on a grand scale. Each summer, monsoons affect every continent on Earth except Antarctica, and are responsible for life-giving rains that sustain the lives of billions of people. In India, home for over 1.1 billion people, the monsoon provides 80% of the annual rainfall. However, monsoons have their dark side as well--hundreds of people in India and surrounding nations die in an average year in floods and landslides triggered by heavy monsoon rains. The most deadly flooding events usually come from monsoon depressions (also known as monsoon lows.) A monsoon depression is similar to (but larger than) a tropical depression. Both are spinning storms hundreds of kilometers in diameter with sustained winds of 50 - 55 kph (30 - 35 mph), nearly calm winds at their center, and generate very heavy rains. Each summer, approximately 6 - 7 monsoon depressions form over the Bay of Bengal and track westwards across India. Four monsoon depressions originated in the Bay of Bengal in the El Niño-weakened monsoon season of 2009. This year's first monsoon depression formed 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 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 second monsoon depression arrived in Pakistan on August 3, and has brought additional heavy rains.

Are the this year's monsoon floods due to global warming?
No single weather event can be attributed to climate change, but a warming climate does load the dice in favor of heavier extreme precipitation events. This occurs because more water vapor can evaporate into a warmer atmosphere, increasing the chances of record heavy downpours. In a study published in Science in 2006, Goswami et al. found that the level of heavy rainfall activity in the monsoon over India had more than doubled in the 50 years since the 1950s, leading to an increased disaster potential from heavy flooding. Moderate and weak rain events decreased over the past 50 years, leaving the total amount of rain deposited by the monsoon roughly constant. The authors commented, "These findings are in tune with model projections and some observations that indicate an increase in heavy rain events and a decrease in weak events under global warming scenarios." We should expect to see an increased number of disastrous monsoon floods in coming decades if the climate continues to warm as expected. Since the population continues to increase at a rapid rate in the region, death tolls from monsoon flooding disasters are likely to climb dramatically in coming decades.

References
Goswami, et al., 2006, " Increasing Trend of Extreme Rain Events Over India in a Warming Environment", Science, 1 December 2006:Vol. 314. no. 5804, pp. 1442 - 1445 DOI: 10.1126/science.1132027

Dave's Landslide blog has some great discussions of the flooding and destruction wrought by the terrible monsoon rains this year in Pakistan, India, Afghanistan, and China.

Donations urgently needed
The massive humanitarian crisis in Pakistan requires a huge response by the international community. Wunderblogger Dr. Ricky Rood, author of our Climate Change Blog, has a friend working in Pakistan who underscored the desperate situation there:

This is the worst natural disaster in the history of Pakistan in terms of number of people and area affected. Although not as many people have been killed as in the 2005 earthquake, we have already nearly 900,000 displaced persons thus far just in Khyber Pakhtunkhwa. Crops are destroyed; shops, hotels, and other business have simply been swept away in Swat, which had just this year been cleared of Taliban and was on the way to recovery; and districts closer to Peshawar and parts of Peshawar district are still, or perhaps again after yesterday/today, under water. After the immediate emergency response, it will be years of rebuilding to replace what has been lost and to start to develop again. I know you have the power to control the weather, so if you cold give us a week or two without more rain at least we could keep the helicopters flying and give people a chance to go to their homes, recover what might still be there, set up tents if we can get enough to them, and start to clean up."

She gave the following recommendations for charities that do work in the flood-ravaged zone, and are effective at getting aid to those who need it the most:

Doctors Without Borders

The International Red Cross

MERLIN medical relief charity

The mobile giving service mGive allows one to text the word "SWAT" to 50555. The text will result in a $10 donation to the UN Refugee Agency (UNHCR) Pakistan Flood Relief Effort.

She mentioned that it is better to send money to the organizations doing the relief work than to try to organize shipments of goods.


Figure 2. Morning radar image of 94L from the Key West radar.

94L
A 1010 mb low pressure system (94L) near the Florida Keys is generating disorganized heavy thunderstorms over Florida and the adjacent waters, and could become a tropical or subtropical depression as early as Wednesday. Current Key West radar shows the rotation of the storm, but the thunderstorm activity has not yet organized into low-level spiral bands. A few areas in the Keys and extreme South Florida have seen 1 - 2 inches of rain thus far from 94L. Wind shear is currently a moderate 10 - 20 knots over 94L, and water temperatures are very warm, 30 - 31°C. Water vapor satellite imagery shows that 94L is forming beneath an upper-level low with plenty of dry air, and there is a substantial flow of dry, continental air wrapping into 94L. This dry air is retarding the development of 94L, and may force the storm to organize into a subtropical storm instead of a tropical storm. A subtropical storm typically has a large, cloud free center of circulation, with very heavy thunderstorm activity in a band removed at least 100 miles from the center. The difference between a subtropical storm and a tropical storm is not that important as far as the winds they can generate, but tropical storms generate more rain. There is no such thing as a subtropical hurricane. If a subtropical storm intensifies enough to have hurricane force winds, than it must have become fully tropical. It usually takes at least two days for a subtropical storm to make the transition to a tropical storm.

Forecast for 94L
The latest SHIPS model forecast predicts that wind shear will stay in the moderate range, 10 - 20 knots, over the Gulf of Mexico this week. The storm's main problem will be dry air, and I don't expect 94L to undergo rapid development. Most of the models bring 94L ashore over Louisiana by Thursday, though the GFDL model predicts 94L could stall off the coast and not make landfall until Friday. If 94L does make landfall Thursday, it is unlikely to be a hurricane, due to all the dry air aloft in the Gulf. However, the GFDL model is predicting that the 1-day delay in landfall to Friday will allow 94L enough time to grow fully tropical and intensify into a Category 1 hurricane. I think this solution is unlikely. Storms that get their start underneath a cold, dry, upper-level low very rarely attain hurricane strength in three days. A 40 - 50 mph tropical or subtropical storm at landfall Thursday or Friday is a much more reasonable forecast.

93L
A tropical wave (Invest 93) in the middle Atlantic Ocean is close to tropical depression status. The disturbance has a well-defined surface circulation, but only a limited amount of heavy thunderstorm activity, thanks to dry air and wind shear of 10 - 20 knots affecting it due to a large upper-level low pressure system to the west. Wind shear is expected to stay in the moderate range, 10 - 20 knots, over the next four days, which is low enough that 93L could become a tropical depression at any time during that period. NHC is giving 93L a 60% chance of developing into a tropical depression by Thursday morning. The GFS, GFDL, and HWRF models predict 93L will develop, and the GFDL forecasts that the storm will become a hurricane. A strong trough of low pressure moving across the central Atlantic is recurving 93L to the north, and the system should only be a concern to shipping interests. None of the reliable computer models are forecasting tropical cyclone development in the Atlantic over the next seven days, other than for 93L and 94L.

Moscow hits 99°F again today
Temperatures at Moscow's Domodedovo airport hit 37°C (99°F) today, the 28th day in row that temperatures have exceeded 30°C (86°F) in Moscow. The average high temperature for August 10 is 21°C (69°F). Moscow's high temperature have averaged 15°C (27°F) above average for the first ten days of August--a truly extraordinary anomaly. Smog and smoke from wildfires continued to blanket the city today, with the Russian Meteorological Agency reporting that pollution due to carbon monoxide, nitrogen dioxide, ozone, and hydrocarbons exceeding the safe limit by factors of 1.2 - 2.2. Air pollution levels peaked at 6.5 times the safe level on Saturday. As I reported in yesterday's post, the heat wave has likely killed at least 15,000 people in Russia so far. There is some slight relief in sight--the latest forecast for Moscow calls for high temperatures of 31 - 33°C (88 - 91°F) Wednesday though Sunday--still 20°F above normal, but better than the 27°F above normal so far this month.

"Hurricane Haven" airing again this afternoon
Tune into another airing of my live Internet radio show, "Hurricane Haven", at 4pm EDT today. Listeners will be able to call in and ask questions. The call in number is 415-983-2634, or you can post a question in the comments area on my blog during the show. You can also email the questions to me today before the show: jmasters@wunderground.com. Be sure to include "Hurricane Haven question" in the subject line. Some topics I'll cover today on the show:

1) Invest 94 and 93
2) A look ahead at the coming two weeks
3) Status of La Niña

Today's show will be about 30 minutes, and you can tune in at http://www.wunderground.com/wxradio/wubroadcast.h tml. The show will be recorded and stored as a podcast.

Jeff Masters

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What's the possibility of 94L going into stationary mode?
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Pat, Are the models moving more East?
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Why does the model thats pointing at my house say BAM on it?
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1234. Patrap
Quoting CCkid00:

his 17 year old son also survived.


I met O'Keeffe when he was Chancellor at LSU ..post K.

Great news in a sad tragedy that they survived.
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1233. Patrap
Quoting Drakoen:
94L may not be aligned with the mid level center seen on radar.


I thinks its off to the West of that Radar Mid Level Drak,,as per da plane,da plane Man.
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1232. papper
Hey!
Long time lurker. Rarely posted. Just wanna see if i have this right.

The swirling bands east to the east coast of florida and the swirl to the east of 94L center are the ULL? and not part of 94L? Correct?

True neophyte here but like to watch and learn.

papper
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1230. will45
Quoting txsweetpea:
Are the HH done with investigating 94L?


no still in should be in till 5:00 est
Member Since: July 18, 2009 Posts: 1 Comments: 994
1229. CCkid00
Quoting Patrap:
Former NASA Administrator Sean O'keefe found alive in Plane Crash in Alaska that took the life of Sen. Ted Stevens and 7 others.

his 17 year old son also survived.
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1227. Patrap
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Damn, looked at 94L few hours ago and now I check back and see this thing, it's blowing up! The ULL is getting crushed, soon what's left of the dry are will be gone. That hot water is doing wonders, shear is not such a factor after all. Seems it likes hanging out in that same spot, been there for about 2 days now.
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1225. Drakoen
94L may not be aligned with the mid level center seen on radar.
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Is 94L far enough West to not be affected by dust entranement from Africa?

Matt
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Pretty impressive structure.
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Quoting IKE:


"No one wants a big storm"?...On this blog?

Sure I rooted for Colin to weaken. I didn't want Bermuda to get hit.

I don't care if the season is 0-0-0. It would be fascinating to see. And if people want to see just fish storms...there's usually plenty in the east-PAC. But when there is one in the east-PAC, I see very few in here commenting on it.


Haha, I meant normal people.. I see your point.
Member Since: July 1, 2008 Posts: 13 Comments: 7340
1219. Levi32
Quoting rocketboy108:
What is the most significant single factor inhibiting storm formation, given the record "heat content",..and SSTs???


Wind shear, dry air, and lack of outflow channels on the northern side (will become more of an issue tomorrow).
Member Since: November 24, 2005 Posts: 635 Comments: 26547
Quoting twhcracker:
wow looks like big rain coming. sure a good thing there is no oil out there. I guess the turtles ate it all.
All those midnight dispursant drops!
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Quoting OpusDei:


Hardcore,
Well 'put'. I suspect I agree with your feelings. For whatever reason I have seen several people today on this blog tell people that MS is "in the clear". While I am not saying this will be a major event, to tell people, who may likely be on the E side of a developing system, that they are "in the clear" seems like a bad idea.
References to is path, guess/forecast is fine, but telling skittish non-weather-freaks seeking information, such information using such terminology as "in the clear" (clearly reference to preparedness) seems like something we shouldn't foster here.
Anyway thanks for helping people get a bit of perspective.
Opus



Like, Like, Like!

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12n53
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1213. Patrap
Floater - RGB Color Infrared Loop
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could be that recon found 2 COCs and will not upgrade until 1 becomes dominant
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Quoting TampaBayStevo:
From here in Tampabay, you can tell 94L is coming to life out there...

Been getting a little gustier all day and getting small bands going through periodically with breif heavy rain. I can see the low clouds moving much faster today than yesterday, definately winding up.


Agree here in Citrus County. No heavy rain, but clouds moving quickly east to west, with the breeze and gusts. Just feels different.
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1210. unf97
Dr. Masters just stated that the A/B High doesn't appear to be too strong in looking at model runs going out long range for the next 10 days.
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1209. OpusDei
Quoting Hardcoreweather2010:




Hardcore,
Well 'put'. I suspect I agree with your feelings. For whatever reason I have seen several people today on this blog tell people that MS is "in the clear". While I am not saying this will be a major event, to tell people, who may likely be on the E side of a developing system, that they are "in the clear" seems like a bad idea.
References to is path, guess/forecast is fine, but telling skittish non-weather-freaks seeking information, such information using such terminology as "in the clear" (clearly reference to preparedness) seems like something we shouldn't foster here.
Anyway thanks for helping people get a bit of perspective.
Opus
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Quoting Patrap:
Get ya groove on 94L.

Floater - Rainbow Color Infrared Loop


Where is the center located for 94l?
Member Since: August 19, 2009 Posts: 0 Comments: 248
wow looks like big rain coming. sure a good thing there is no oil out there. I guess the turtles ate it all.
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Are the HH done with investigating 94L?
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1205. Patrap
Former NASA Administrator Sean O'keefe found alive in Plane Crash in Alaska that took the life of Sen. Ted Stevens and 7 others.
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Quoting MississippiWx:


Great structure.
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can someone please answer this question-what is supposed to pull this system to the wnw, and is it still on same course as before? thanks in advance:)
Member Since: September 10, 2008 Posts: 0 Comments: 1291
Quoting gordydunnot:
Stormchaser can't happen 10ft elevation Atlantic would have to rise that much for me to flood.


I was messing around.
Member Since: August 11, 2008 Posts: 0 Comments: 2315
IKE.. Im a novice too.. Just trying to learn.. I Try not to forecast..forecasting 94L landfall for me would be throwing a dart on a map that has houston to mobile outlined.. HA!!!

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Stormchaser can't happen 10ft elevation Atlantic would have to rise that much for me to flood.
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Quoting cheetaking:
My thoughts on the current activity:

850mb Vorticy:


Wind Shear:


94L is getting very interesting quickly. It clearly has a strong low-level vorticy going, with spiral bands now appearing as well, convection starting to wrap around the center, plus some very impressive-looking outflow channels to the east and south. Wind shear is down to around 10 kts over almost the entirety of the system, SST's are ridiculously high, and it will be passing very close to a loop current eddy if it keeps on its westward course. So I fully anticipate a tropical storm within 24-36 hours, if not sooner. And the only thing I can see that might keep it from strengthening quickly is the dry air on its northwest side. Except for that, this storm is in very favorable conditions.

Finally, that new wave near 12N 48W is no immediate threat, but it bears watching in 3-5 days or so. The entire Caribbean Sea has almost no wind shear whatsoever over it, and the wave will be headed right through the highest area of TCHP. However, since it appears to be more of a mid-level swirl at the moment, I'll reserve judgment until I see a surface low develop. I'm just saying that the potential is there.


The eddy is very weak, its just now forming again, since it broke off about two months ago, there's warmer waters in the eddy, but its not like a full eddy with all Caribbean warm water being feed into it. It's got a little bit of the warm water entering it.

It not like the eddy when Katrina and Rita blew up after passing over it.

Member Since: August 11, 2008 Posts: 0 Comments: 2315
1196. Patrap
Quoting rocketboy108:
What is the most significant single factor inhibiting storm formation, given the record "heat content",..and SSTs???


Shear aloft..in 2010
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1195. SLU
Quoting stoormfury:
SLU what is your take on disturbance east of barbados. it looks healthy with an anticyclone above it


Well it's a well defined wave and it may bring some showers to the islands tomorrow but i'll prefer to monitor it for another 12 hours before I commit to development. It does have some good potential down the road though.
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1193. Patrap
Get ya groove on 94L.

Floater - Rainbow Color Infrared Loop
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Okay. Time for laundry and you know, stuff.

Later!
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I bet TD or mabye even a TS beacuse of a very nice looking sat pic.
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What is the most significant single factor inhibiting storm formation, given the record "heat content",..and SSTs???
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This guy with the 10% needs to be watched.


Good anti-cyclone.


Good divergence


little to no convergence


94L has good divergence and convergence, with minimal shear.
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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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