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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Quoting StormW:
If you get a chance, check out post number 26 on my blog.

Thanks!


WOW!!! Congrats StormW that is some high fluting company you are holding there..
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Quoting StormW:
If you get a chance, check out post number 26 on my blog.

Thanks!


awesome!!
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Quoting Drakoen:
Continues to get better organized. Recon finding low pressures near 1008mb.


That thing. Is a fast-developing tropical depression.
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1333. quante
Well it is dark, gray and rainy here in West Palm. Feels ominous. A very scientific analysis. LOL
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1332. Drakoen
Recon found a west wind and pressure 1007.8mb
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Quoting Levi32:


Struggling with itself? A little bit because it isn't quite vertically stacked, but I expect it will eventually stack itself and that won't be a problem anymore.


Levi, when do YOU think it'll make TD status, or should I say..when will NHC abel it? I can't decipher HH feed....is what they're finding in fact a TD?
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Quoting Ossqss:


Slow site, removed
Cool,that blue circle finally stopped spinning.
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Storm, Drak

Here is the thing throwing me for a loop. You look at some of the different models and I get the impression that the models are thinking that this 94 will not get stacked or organized enough.

Is this why some models are showing different landfall points?

Also I couldnt help but notice that this may bring at best 2-4 in of rain depending on what happends tonight...so what kind of real intensity will this bring?


your thoughts?
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models have it going into la but it looks to be going towards the upper texas coast
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Afternoon all. Shucks, I got back too late for Hurricane Haven. I wanted to ask a couple questions about intensity forecasting.

Question: NHC has made great strides in recent years with the quality of forecasts for TC tracks. However, there is less conficence in the intensity forecasts, and flawed track forecasts are often tied to intensity forecasts which do not verify. What aspect or aspects of TCs and their environment do you think need to be better understood if intensity forecasts are to improve?

Alternatively, the 2010 season seems more or less on track to become an above average season, much as was forecast by several mainstream agencies. However, despite a strong positive signal for TC formation, most of the season's TCs have struggled to gain TS strength and to maintain it. What factors do you think have contributed most to the limited development, and do you think those factors will continue to influence the 2010 season?


But I got back here too late...
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1007.8 mb
(~ 29.76 inHg)

Getting a little better organized.
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Back from the afternoon work issues......Looks like Danielle might be forming right before our eyes over the next 24 hours if the current trends continue.....Really nice presentation at the moment, particularly on the radar loops, from this morning.
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1324. Levi32
Quoting scott39:
Levi, Do you see 94L struggling with 94L now?


Struggling with itself? A little bit because it isn't quite vertically stacked, but I expect it will eventually stack itself and that won't be a problem anymore.
Member Since: November 24, 2005 Posts: 635 Comments: 26686
Quoting Drakoen:


If you noticed, Avila mentioned nothing about a subtropical cyclone but rather a tropical depression.


Yeah, I noticed that on the TWO. Masters has really gone down hill in his tropical analysis, IMO. He spends too much time worrying about global warming. His blog...he can do what he wants.
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Quoting MississippiWx:
I still don't see why Jeff Masters is stating that this could become sub-tropical. It has no features of a sub-tropical cyclone and is purely warm-core.


Its warm cored. nrt posted that on the previous blog entry.
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Radar loop of 94L's MLC on the Casablanca, Cuba radar. MLC doesn't appear to be moving due north.

Link
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Quoting xCat6Hurricane:


Incorrect.


Can you tell which way it's moving? Long range radar and visible satellite both look like the surface precip is moving a little northward now. What is best to use to judge this?
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1318. Drakoen
Quoting MississippiWx:
I still don't see why Jeff Masters is stating that this could become sub-tropical. It has no features of a sub-tropical cyclone and is purely warm-core.


If you noticed, Avila mentioned nothing about a subtropical cyclone but rather a tropical depression.
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Quoting earthlydragonfly:


This is the same shot zoomed in a bit..
That is so beautiful. Is it color enhanced or is the purple true? Just gorgeous.
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Quoting MrNatural:
Is that an eye I see trying to form in 94L?


Negative.
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Quoting Tazmanian:
may i have a link too the Recon page


recon
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may i have a link too the Recon page
Member Since: May 21, 2006 Posts: 5091 Comments: 115379
I still don't see why Jeff Masters is stating that this could become sub-tropical. It has no features of a sub-tropical cyclone and is purely warm-core.
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The ULL associated with 94L is looking more and more insignificant in shearing the storm.
Member Since: June 27, 2010 Posts: 0 Comments: 82
1310. scott39
Quoting angiest:


Huh?
LOL, Typo-Leave out 1 of the 94Ls.
Member Since: June 13, 2009 Posts: 0 Comments: 6897
I'll bet the real debate at the NHC is this a t.d.,t.s. or ext.s.
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1306. Drakoen
Continues to get better organized. Recon finding low pressures near 1008mb.
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1305. Ossqss


Slow site, removed
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Is that an eye I see trying to form in 94L?
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Quoting StormW:


cmmn chief...
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1302. angiest
Quoting scott39:
Levi, Do you see 94L struggling with 94L now?


Huh?
Member Since: August 26, 2006 Posts: 16 Comments: 4766
Quoting sammywammybamy:
94L Moving N Now.


Incorrect.
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This is the same shot zoomed in a bit..
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1297. scott39
Quoting MississippiWx:
One thing is for sure...94L wants to be a large cyclone.
Thats what I was wondering.
Member Since: June 13, 2009 Posts: 0 Comments: 6897
1296. Drakoen
Quoting Goldenblack:
Hey Drak, I have been dreadfully off in my prediction today....can you give me a little bit more of your thinking with the vertical stacking, the llc is further off to the north and west, the mlc needs to join it, right? That is what I am seeing?



It is off to the northwest. It is very slight vertically titled.
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One thing is for sure...94L wants to be a large cyclone.
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1294. scott39
Levi, Do you see 94L struggling with 94L now?
Member Since: June 13, 2009 Posts: 0 Comments: 6897
1293. swlavp
Quoting LouisianaWoman:
Well neighbor, looks like we might have a hurricane party coming up for this weekend. Better clear out in time for that Shrimp Festival. lol
LOL Absolutely!!! Already lookin forward to goin....Can't wait to see the Ballamy Brothers...lol...Course, I just admitted my age
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1291. BFG308
Dragonfly, nice pic!

DestinJeff, I completely agree with your blogcast! Hilarious! But you had an obvious omission-- plenty of doomcasts and "K"-casts (as it is headed in that general direction)

I'd like to see it in a TW Outlook format though. That would really nail it for me
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1290. newt3
long time lurker here. decided to join. What, if any, effects should the panhandle of florida expierence with 94l in the coming days? Thanks in advance and hope to learn alot from u guys!
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Well neighbor, looks like we might have a hurricane party coming up for this weekend. Better clear out in time for that Shrimp Festival. lol
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Quoting earthlydragonfly:


Thank you very much... It was a lot of work to get this one shot.. and the pier has termites so we (my son and I) where covered in flying bugs all night... but worth it


Sorry about the bugs. They tend to come with the east wind.
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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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