Pakistan's Katrina; 94L could develop in Gulf of Mexico
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
Reader Comments
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The Gulf of Mexico is its feed but it is close to the Gulf Stream where the warm waters come up from the Caribbean and through the straits.
http://www.goes.noaa.gov/HURRLOOPS/gulfwv.html
Notice the Northern Gulf, the area west of Greenland, Hudson Bay, Sea of Japan, and the NE Pacific north of Hawaii.
that comment was removed how did you quote it
That's why I'm lurking and watching, a little worried it's going to take it's sweet time moving North and get picked up later by the front and end up hitting the FL Panhandle. Like I said last night I just hope it does pull any rapid strengthening which currently doesn't look likely but things can always change.
don't get too excited. Most likely they will raise it to 70-80% and wait for recon to get in there. IMO 94L has about another 12-18 hours before it becomes a tropical cyclone
Agree Reed, although 70% is the natural milestone
Sorry, I don't see how StormChaser81 was being rude or arrogant. Jeff stated that there was 40-50 mph winds coming into Orlando, which isn't true. If he meant gusts associated with convective downbursts, he should have specified. Jeff is known for creating severe weather from nothing.
I'm fine with that, humbled hardly, he made it sound like 40-50 mph winds where moving across FL, not in rain showers, he also said very strong wind gust in these storms, If I'm not mistaken that's two different sentences, explaining two different things.
Of course your going to have down burst and wind gust with such storms.
He always blows things up more than they need to be.
I'm not personnel attacking him, its his observations im attacking.
If hes going to post stuff like that, should be more careful about wording.
August 10th, 2010
In my last blog entry, I wrote about the rapid ramp-up in activity that typically occurs the first week or two of August. It now appears that the next named storm of the 2010 season is taking shape in the eastern Gulf of Mexico. A feature that we identified as Tropical Disturbance 34 last weekend is steadily becoming better organized just west of the lower Florida Peninsula.
Although a recon plane is scheduled to investigate the disturbance this afternoon, I really don’t think that they’ll be able to find out anything that we don’t already know. The disturbance is located in an area that has plenty of good surface observation stations. These stations indicate that there is no question it has a low-level circulation center, a requirement for classification as a tropical depression. Winds around the low center are in the 20-25 mph range, too low for tropical storm strength. Thunderstorms around the low center remain a bit weak and are situated mostly south of the center, a sign of somewhat unfavorable winds aloft. But recent satellite imagery does indicate that upper-level conditions are steadily becoming more favorable for development.
The bottom line is that though this disturbance may not fully meet all of the criteria for classification as a tropical depression at present, we think that it’s well on its way to becoming a depression by tonight and the fourth named storm of the 2010 hurricane season tomorrow. Its name would be Danielle. The next questions would be where will Danielle most likely track and how strong could it get.
Below is the latest model guidance for the disturbance. Models have been in very good agreement for days now that the disturbance would track generally toward southeast Louisiana. We agree, and or track (in dark blue) is similar to most of the guidance though a bit south of guidance to start out with and a little east of guidance across eastern Louisiana. It’s a tough call as to exactly where it might move ashore. The current slow westward movement could even increase the risk that it might move inland toward the central or even southwest Louisiana coast.
As for its intensity at landfall, model guidance appears centered around maximum sustained winds of between 50 and 60 mph at landfall. Basically, a moderate tropical storm. I am concerned, though, that conditions may become quite favorable for strengthening in the last 12 hours before it reaches the Louisiana coast on Thursday. In that case, intensification could be quite rapid as it’s making landfall. So it’s not out of the question that it could reach hurricane strength as it approaches the coast. I estimate those chances at roughly 30%.
The good news is that with a limited region of moisture and favorable winds aloft, the storm is not likely to be very large. It should be average or a little below average in terms of its size as a tropical storm. If it reaches hurricane intensity, then its size would be smaller than average. More than likely, any hurricane force winds would be confined to squalls over the water rather than inland over southeast Louisiana.
Ah, I see that the recon plane just left Keesler AFB in Biloxi a few minutes ago (11:08AM CDT). With only a short distance to travel to get to the disturbance, it won’t be long before the plane is near the center
by Chris Hebert
real news
agreed
I don't believe 94L will be going anywhere fast as current steering are weak enough for very little displacement.
Depends on which develops first.... my friend
If it moves more west towards Central or Western La it could be Friday
I'm asking because of the argument on whether or not this (94L) would be subtropical vs. tropical...maybe a "cool" warm core system takes on some of the characteristics of a subtropical storm. Kind of like a hybrid approach...eh, just speculation, but fun to theorize!
Just like Oklahoma Corporation Commissioners:-O
Link
This is the band currently training over my house.
I agree. If the trend with the convection continues, NHC will mention it in the TWO, possibly as early as this evening.
They WILL NOT.... and I repeat WILL NOT. do that. They may designate 93l a depression but the HH are enroute to 94L I believe... and they will wait for the HH data
Lmao you need to grow up a little.
Keys are getting some good storms!
Radar's down for maintenance...LOL
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