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 HurricaneIsabel:
I'm with IKE on this one boys, it will lose tropical depression status before it hits land


You just said Category 3. Sheesh kid. Make up your mind.
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Quoting pfdfirefighter:
Just told my wife about TD 5 she asked how strong was it going to be? The last 2 times she has switched grades As a teacher we had Katrina and gustav, BTW she is switching grades again!!!

Make her resign asap! lol
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2184. IKE
Quoting HurricaneIsabel:
I'm with IKE on this one boys, it will lose tropical depression status before it hits land


I never said that.
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2183. xcool


update...
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09 do you think 93L has done better today?
Member Since: May 21, 2006 Posts: 5091 Comments: 115613
Read on another forum that TD5 has been named TS Danielle, this isnt true is it?
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Quoting Tazmanian:
am forcasting a strong cat 3 or 5 hurricane from this



i eat raw fish for life


and what..... with no possibility of Cat4?

Just sayin....... LOL
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2179. mobal
Quoting Hurricanes101:
I come here and take the posts of a few to heart

Drak, StormW, Levi and a few others

many of the others I just laugh at lol

If I did not mention you with the top 3, do not get offended


You are smart!
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Quoting MiamiHurricanes09:
Yes right now upper level conditions are favorable for more intensification of 05L. However, the deep-layer ridge over the S.E US will be shearing it with easterlies starting tomorrow according to the 18z GFS.


GFS is the outlier...not a fan at the moment. I thought eariler you were going with GFDL? At least that is what you said. Not buying shear with this system and easterly shear wont have huge impact.
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2177. Ossqss
Selective Model Tool

This will be interesting to use as we move forward this year. Never had an interactive one with this many layovers and options.

Off to stock up on Dinty Moore and Slim-Jims for the kit :) out>>>
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Mature Up people! (wow, no home trainin')
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SPECIAL UPDATE TD5 8/10/10
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2171. mobal
Quoting pfdfirefighter:
Just told my wife about TD 5 she asked how strong was it going to be? The last 2 times she has switched grades As a teacher we had Katrina and gustav, BTW she is switching grades again!!!



Shes most likely safe on this one, unless your timeframe is Sept......
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Quoting Patrap:
5 years after K,,most dont know what occurred here, but they can tell ya the last 5 American Idol winners or Survivor.

Pfffth.


From Mobile to Houma was affected by that Historic Storm,..just becase some got wacked by 4 the year before,,some dismiss our impact cuz they saw a Lot of whats wrong still with America.

So the memory pains them seems.

Those of us who experienced her from NOLA to Pascagoula realize that "calamity knows no borders, only men's minds and maps do"...



Never wish for Calamity to strike your State or area..you just may get a tad more than you wished for.

Well said! Just kidding about the football stuff, I'll tip 'da vodka toward 'ya on Thursday
Member Since: July 30, 2010 Posts: 0 Comments: 491
Quoting MiamiHurricanes09:
Yes right now upper level conditions are favorable for more intensification of 05L. However, the deep-layer ridge over the S.E US will be shearing it with easterlies starting tomorrow according to the 18z GFS.



ok
Member Since: May 21, 2006 Posts: 5091 Comments: 115613
I come here and take the posts of a few to heart

Drak, StormW, Levi and a few others

many of the others I just laugh at lol

If I did not mention you with the top 3, do not get offended
Member Since: March 10, 2010 Posts: 1 Comments: 7874
winds need to go up olny 5kt and we have a TS
Member Since: May 21, 2006 Posts: 5091 Comments: 115613
Quoting Tazmanian:



shear?






its olny 5kt 09
Yes right now upper level conditions are favorable for more intensification of 05L. However, the deep-layer ridge over the S.E US will be shearing it with easterlies starting tomorrow according to the 18z GFS.
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Where is Storm I need to know what he thinks!!
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Just told my wife about TD 5 she asked how strong was it going to be? The last 2 times she has switched grades As a teacher we had Katrina and gustav, BTW she is switching grades again!!!
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starting to look more like TS already
even though winds ant their yet
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ugh


we got downcaster and wishcaster on here lol
Member Since: May 21, 2006 Posts: 5091 Comments: 115613
As I said last night, howdy Danielle!

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LOL aquak that is hilarious. Cute little fella.
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Quoting AllStar17:
This blog is ridiculous right now.

Just to prove how wrong the NHC's forecast on Colin was:
On August 5th at 5:00 pm, Colin was predicted to be a 70 mph Tropical Storm 96 hours out. What was it 96 hours out? No longer a tropical cyclone.

Intensity forecasts are the hardest thing to predict in a tropical cyclone.


I agree lol, the NHC itself even admits difficulties in predicting the intensity of tropical systems
Member Since: March 10, 2010 Posts: 1 Comments: 7874
Quoting btwntx08:
back later i have a headache




i send in a bare it will make you feel better
Member Since: May 21, 2006 Posts: 5091 Comments: 115613
Quoting StormW:


With easterly shear, it basically moves with the storm vice against it.

The thing with easterly shear is, as I stated earlier today, if a storm is moving in the same direction, and at the same speed as the shear, it is not as detrimental. If you remember with Bonnie, the upper level shear was quite a bit faster than what Bonnie was moving as forward speed. This has the tendency to slightly tilt the system, but not decoupling it, and allows the system to give up heat energy. In this case, if TD5 moves in tandem both direction and speed wise, this should not occur. So even though the upper environment may not be optimal, it will allow for some strengthening to occur.

Another great explanation. Thank you so much, Storm! Yeah, I think I got it. :-) Kinda like rolling a ball along with a stick. If they're both going at the same speed, that can be a good thing.
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Dry air I buy but not sheer. I also only thing it will be a TS at most but not due to shear. It is time. It is still a very broad disorganized system. Look at microwave and you will see that the low levels do not look good at all. It will run out of time to completely organize. very shallow warm core low as well.
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uh oh

Recoon found dat surface circulation
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2151. scott39
Quoting StormW:


With easterly shear, it basically moves with the storm vice against it.

The thing with easterly shear is, as I stated earlier today, if a storm is moving in the same direction, and at the same speed as the shear, it is not as detrimental. If you remember with Bonnie, the upper level shear was quite a bit faster than what Bonnie was moving as forward speed. This has the tendency to slightly tilt the system, but not decoupling it, and allows the system to give up heat energy. In this case, if TD5 moves in tandem both direction and speed wise, this should not occur. So even though the upper environment may not be optimal, it will allow for some strengthening to occur.
When can we anticipate to see strong convection build around the center?
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The NHC continues to suggest that all 93L needs is an increase of convection before being classified as 06L.

SHOWER ACTIVITY ASSOCIATED WITH A LOW PRESSURE SYSTEM LOCATED ABOUT
750 MILES EAST-NORTHEAST OF THE NORTHERN LEEWARDS ISLANDS HAS
DECREASED OVER THE PAST FEW HOURS. ALTHOUGH UPPER-LEVEL WINDS ARE
NOT EXPECTED TO BECOME VERY CONDUCIVE FOR DEVELOPMENT...AN INCREASE
IN THUNDERSTORM ACTIVITY COULD RESULT IN THE FORMATION OF A
TROPICAL DEPRESSION
. THERE IS A HIGH CHANCE...60 PERCENT...OF THIS
SYSTEM BECOMING A TROPICAL CYCLONE DURING THE NEXT 48 HOURS AS IT
MOVES TOWARD THE NORTH AND NORTH NORTHEAST OVER THE ATLANTIC.
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This blog is ridiculous right now.

Just to prove how wrong the NHC's forecast on Colin was:
On August 5th at 5:00 pm, Colin was predicted to be a 70 mph Tropical Storm 96 hours out. What was it 96 hours out? No longer a tropical cyclone.

Intensity forecasts are the hardest thing to predict in a tropical cyclone.
Member Since: June 29, 2009 Posts: 13 Comments: 5315
2146. aquak9
.
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Quoting MiamiHurricanes09:
Yeah dry air will be gone with the wind as the cold low (ULL) advects westward. The only problem it will face is easterly shear.



shear?






its olny 5kt 09
Member Since: May 21, 2006 Posts: 5091 Comments: 115613
I wish this thing would get a move on...I don't like it sitting and spinning like this. The water is too darn hot. Even an extra 8 hours could make a difference in the long run.
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2142. angiest
Quoting spathy:

Psychic Bob says if its what is best for you.....
The answer is YES!
Or is that fatalistic BOB.
Was anyone watching Key West radar earlier today when 94/TD5 transitioned from subtropical in nature(big 100 mile open spin) to closing in and start the warming banding phase.
I wish I could isolate that radar and re post it.
Quite interesting process.


Capture of the approximate time when I noticed the LLC coming together on the Key West Radar. My fix is actually fairly close to the initial advisory (I have 25 and 84 roughly).

Photobucket
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Ohey, there's a tropical storm warning for me. Woot!
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there is no wind shear what so evere overe TD 5

Member Since: May 21, 2006 Posts: 5091 Comments: 115613
Quoting CybrTeddy:


I do not see TD5 becoming a Category 1 hurricane even. Could see a 60 mph TS.


With the upper level air patterm, and all the dry air, I believe 60mph is the high end of the envelope....... 50-55mph seems reasonable.... if it stalls, you could see 60, but I am pretty comfortable with the official forecast.

Seems like the ULL's have had a very significant impact on the season so far..... will be interesting to see if this pattern persists.......
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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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