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Hurricane Season 2011: Tropical Storm Washi (Western North Pacific Ocean)
12.21.11
 
Accumulated rainfall over the Philippine Islands from December 16-17, 2011. › View animation
This animation shows the accumulated rainfall over the Philippine Islands from December 16-17, 2011.
Credit: Created by Zhong Liu, GES DISC using Real-Time TMPA-RT data product in the NASA Giovanni data analysis system.
NASA Satellite Analysis Shows Tropical Storm Washi's Rains Move Over Philippines

An animation created at NASA shows how rainfall from Tropical Storm Washi spread over the Philippines on Friday and Saturday, Dec. 16 and 17, 2011. Washi brought flooding rainfall that killed more than 900 people.

An animation showing the onset and movement of rainfall from Washi was created by Dr. Zhong Liu, at the Goddard Earth Sciences Data and Information Services Center at NASA Goddard Space Flight Center in Greenbelt, Md. Zhong used Real-Time data from the Tropical Rainfall Measuring Mission (TRMM ) satellite's Multi-Satellite Precipitation Analysis (TMPA-RT) data product in the NASA Giovanni data analysis system.

The animation shows the accumulated rainfall over the Philippine Islands from December 16-17, 2011. The heaviest rains from Washi, shown in red and magenta, were centered over northwestern Mindanao, the large southern island of the Philippines. In these areas, such as Cagayan de Oro and Iligan City, flooding triggered by Washi's rains has caused hundreds of fatalities. Washi dissipated in the South China Sea on December 20, 2011.

Text Credit: Zhong Liu/Rob Gutro
GES DISC/NASA's Goddard Space Flight Center, Greenbelt, Md.



Dec. 20, 2011

Rainfall estimates from TRMM are shown here for the period Dec. 13 to 20, 2011 for the southern Philippines. › View larger image
Rainfall estimates from the TRMM data are shown here for the period Dec. 13 to 20, 2011 for the southern Philippines. Storm symbols mark Washi's track. Rainfall totals are on the order of 200 to over 250 mm (~8 to 10 inches, shown in green and yellow) along Mindanao's east coast where Washi made landfall, but the highest amounts are along the northwest coast, where totals are on the order of 300 to over 400 mm (~12 to over 16 inches, shown in orange and red).
Credit: SSAI/NASA, Hal Pierce
Image of accumulated rainfall over the Philippine Islands from December 13-18, 2011. › View larger image
Image of accumulated rainfall over the Philippine Islands from December 13-18, 2011, showing the impact of Tropical Storm Washi. The heaviest rains from Washi, shown in red and magenta, were centered over northwestern Mindanao, the large southern island of the Philippines. In these areas, such as Cagayan de Oro and Iligan City, flooding triggered by Washi's rains has caused hundreds of fatalities.
Credit: Created by Zhong Liu, GES DISC using Real-Time TRMM Multi-Satellite Precipitation Analysis (TMPA-RT) data product in the NASA Giovanni data analysis system.
Animation of infrared data from NASA's TRMM satellite of Tropical Storm Washi's movements on Dec. 16 › View TRMM Animation
This is an animation of infrared data from geostationary meteorological satellites of Tropical Storm Washi's movements on Dec. 16 from 0400 UTC to 2300 UTC (12 a.m. to 7 p.m. EST) generated from NASA's Hurricane Data Analysis Tool in the NASA GES DISC at NASA Goddard Space Flight Center, Greenbelt, Md.
Credit: Created by Zhong Liu, NASA GES DISC/George Mason University, using the GES DISC Hurricane Data Analysis Tool.
NASA's TRMM Satellite Measured Washi's Deadly Rainfall

NASA's Tropical Rainfall Measuring Mission (TRMM) satellite was providing forecasters with the rate in which rainfall was occurring in Tropical Storm Washi over the last week, and now TRMM data has been compiled to show rainfall totals over the devastated Philippines.

Washi, known locally in the Philippines as Sendong, began as a tropical depression on December 13, 2011 in the West Pacific Ocean about 2150 km (~1333 miles) due east of the southern Philippines. Washi only intensified slightly and never exceeded tropical storm intensity as it tracked due west towards the southern Philippines' island of Mindanao.

Washi made landfall on the east coast of Mindanao on the afternoon of Dec. 16 as a moderate tropical storm with sustained winds reported at 55 knots (~63 mph). Despite its modest intensity, Washi had a huge impact on the island. As Washi made its way across Mindanao, it dumped heavy rains over parts of the island, which in turn triggered flash floods and mudslides. These turned out to be catastrophic as over 900 people were killed with hundreds more reported missing when entire villages where swept away.

Rainfall estimates from the TRMM-based, near-real time Multi-satellite Precipitation Analysis (TMPA) at the NASA Goddard Space Flight Center, Greenbelt, Md. were compiled for the period of Dec. 13 to 20, 2011 for the southern Philippines. TRMM is a joint mission between NASA and the Japanese space agency JAXA.

Rainfall totals are on the order of 200 to over 250 mm (~8 to 10 inches) along Mindanao's east coast where Washi made landfall, but the highest amounts are along the northwest coast, where totals are on the order of 300 to over 400 mm (~12 to over 16 inches). To put the rainfall in perspective, 16 inches is the equivalent of about four months of rainfall in Washington, D.C.

In the southern Philippines places like Cagayan de Oro City and Iligan City suffered the most devastating mudslides. In addition to deforestation and weak construction, poor warnings are being blamed for the deadliest cyclone disaster to hit the Philippines in three years. The residents of the southern Philippines see far fewer cyclones per year than in the north, and most of the heavy rain was reported to have fallen over the mountains before flowing down in raging rivers.

Text Credit: Steve Lang
SSAI/NASA's Goddard Space Flight Center, Greenbelt, Md.




































Dec. 19, 2011

NASA Sees Rainfall Waning in Deadly Tropical Storm Washi › View larger image
TRMM provided a "top down" rainfall analysis of Tropical Storm Washi on Dec. 17 and 18. Light to moderate rainfall (green and blue) was falling throughout the storm a rate between .78 to 1.57 inches/20 to 40 mm per hour). The areas of heavy rainfall (red) were occurring around the center of the storm, falling at a rate of 2 inches/50 mm per hour.
Credit: SSAI/NASA, Hal Pierce
NASA Sees Rainfall Waning in Deadly Tropical Storm Washi

Tropical Storm Washi brought deadly rainfall to the southern Philippines over the weekend as NASA's TRMM satellite showed heavy rainfall in the small storm. Washi is known locally in the Philippines as Tropical Storm Sendong.

The storm's tropical storm force winds may have only been 100 miles (160 km) in diameter, but the rainfall totals within this compact storm were high and caused severe flooding, landslides and almost 600 deaths, according to Taiwan News.

According to the Associated Press, two of the cities hardest hit were Cagayan de Oro and Iligan. About 239 people perished in Cagayan de Oro and another 195 died in Iligan from the flood waters. More than 400 people are still reported missing. Streets are flooded, power remains out and drinking water is unavailable to 500,000 people.

NASA's Tropical Rainfall Measuring Mission satellite called TRMM passed over Washi on Dec. 17 and 18, capturing rainfall rates within the storm. On both days, areas of heavy rainfall could be seen around the center of circulation. The rain was falling at a rate of 2 inches/50 mm per hour in those areas.

On Dec. 17, although Washi's center of circulation had already crossed Mindanao and was in the South China Sea, outlying bands of thunderstorms were still bringing heavy rainfall over the island region. On that day at 2100 UTC (4 p.m. EST), Washi had maximum sustained winds near 45 knots (52 mph/83 kmh) and was located about 265 miles south-southwest of Manila, Philippines near 10.2 North and 119.0 East.

On Dec. 18, NASA's TRMM satellite saw most of the heavy rainfall in Washi's northeastern quadrant, still falling at over 2 inches/50 mm per hour. Washi was over the South China Sea and all of the precipitation from the storm had moved west of the Philippines. The center was located about415 miles east of Ho Chi Minh City, Vietnam, near 9.9 North and 113.9 East at 2100 UTC (4 p.m. EST). Maximum sustained winds were still holding at 45 knots (52 mph/83 kmh).

On Monday, Dec. 19, Tropical Storm Washi had moved further away from the Philippines, and closer to Vietnam as it tracked in a westerly direction through the South China Sea. At 1500 UTC (10 a.m. EST), it was about 235 miles east of Ho Chi Minh City, Vietnam, near 10.5 North and 110.7 East. Its maximum sustained winds were down to 25 knots (29 mph/46 kmh) as a result of stronger wind shear. Infrared satellite imagery showed that the banding of thunderstorms around the center had weakened and dispersed. Even the low-level center of circulation was difficult to pinpoint.

Washi is dissipating over the open ocean in the South China Sea today.

Text Credit: Rob Gutro
NASA's Goddard Space Flight Center, Greenbelt, Md.



Dec. 16, 2011

Tropical Storm Washi's Rainfall Intensifies Over Larger Area› View larger image
This TRMM 3-D image created from data on Dec. 15, showed Tropical Storm Washi's tallest thunderstorms reached heights of over 15 km (~9.3 miles) and were located in the feeder bands converging into northwest side of the storm.
Credit: NASA/SSAI, Hal Pierce

Tropical Storm Washi's Rainfall Intensifies Over Larger Area› View larger image
TRMM provided a "top down" rainfall analysis of Tropical Storm Washi on Dec. 15. Light to moderate rainfall (green and blue) was falling throughout the storm a rate between .78 to 1.57 inches/20 to 40 mm per hour). There were more areas of heavy (red) rainfall around the center of the storm than on the previous day.
Credit: SSAI/NASA, Hal Pierce

Tropical Storm Washi's Rainfall Intensifies Over Larger Area› View larger image
NASA's Terra satellite flew over Tropical Storm Washi on Dec. 16 at 01:45 UTC and captured this visible image of the storm. The western half of Washi was already over Minandao in the southern Philippines.
Credit: NASA Goddard MODIS Rapid Response Team
NASA Sees Tropical Storm Washi's Rainfall Intensify Over Larger Area

NASA's TRMM satellite noticed that as Tropical Storm Washi approached the Philippines' island of Mindanao heavy rainfall had become more widespread than the previous day. NASA's Terra satellite captured Washi making landfall early today.

Early on Dec. 15 when NASA's Tropical Rainfall Measuring Mission (TRMM) satellite passed over Tropical Storm Washi, (known as Sendong in the Philippines) there was one area to the southwest of the center that had heavy rainfall. When TRMM passed over Washi later on Dec. 15 at 1515 UTC (10:15 a.m. EST), heavy rainfall was more widespread throughout the entire storm. TRMM saw areas of heavy rain, falling at 2 inches (50 mm) per hour, in the east, north and western quadrants of the storm.

That rainfall analysis was created at NASA's Goddard Space Flight Center in Greenbelt, Md. using the TRMM Microwave Imager (TMI) and Precipitation Radar (PR) data overlaid on an enhanced infrared image from the satellite's Visible and InfraRed Scanner (VIRS). The rainfall analysis showed that Washi was much better organized and bands of thunderstorms spiraling into the center of the storm.

TRMM PR data was also used to create a 3-D image from the same satellite overpass and showed numerous heavy thunderstorms were located throughout the tropical cyclone. The tallest thunderstorms reached heights of over 15 km (~9.3 miles) and were located in the feeder bands converging into northwest side of the storm.

On Dec. 16 at 01:45 UTC, NASA's Terra satellite flew over Tropical Storm Washi and captured a visible image of the storm using the Moderate Resolution Imaging Spectroradiometer (MODIS) instrument. MODIS showed the western half of Washi was already over Mindanao in the southern Philippines. Mindanao is the second largest and easternmost island of the Philippines.

Warnings in effect in the Philippines for Dec. 16 include: Public storm warning signal #2 for Mindanao: Misamis Oriental & Occidental, Camaguin Island, Bukidnon, Lanao del Norte & Sur and Zamboanga Provinces. Public storm warning signal #1 is in effect for Mindanao: Bohol, Siquijor, Southern Cebu, Negros Oriental and Southern Negros Occidental; and for Visayas: Surigao Del Norte, Agusan del Norte & Sur, Davao del Norte, Compostela Valley, North Cotabato and Maguindanao; and in Luzon: Palawan.

At 1500 UTC (10 a.m. EST) on Dec. 16, Tropical Storm Washi's maximum sustained winds were near 50 knots (57 mph/92 kmh). Those tropical storm-force winds extend out 50 miles (80 km) from the center making the storm over 100 miles in diameter.

Washi was about 230 miles (370 km) east-northeast of Zamboanga, in Minandao Philippines near 8.4 North and 125.5 East. Washi was moving to the west-northwest at 13 knots (15 mph/24 kmh) but slowing down as it interacts with land. As Washi slowed, the Joint Typhoon Warning Center (JWTC)noted that convection (rising air that forms thunderstorms that make up the tropical storm) and thunderstorms spread to all quadrants of the storm. The strongest thunderstorms appeared over the southwestern quadrant this morning.

Washi was making landfall over Mindanao on Dec. 15 at 1500 UTC and will continue moving westward. The JTWC expects Washi to re-intensify over the Sulu Sea and make a final landfall this weekend in Vietnam.

Text Credit: Rob Gutro
NASA's Goddard Space Flight Center, Greenbelt, Md.



Dec. 15, 2011

TRMM provided a › View larger image
TRMM provided a "top down" rainfall analysis of Tropical Storm Washi on Dec. 15. Light to moderate rainfall (green and blue) was falling throughout the storm a rate between .78 to 1.57 inches/20 to 40 mm per hour). There was a small area of heavy (red) rainfall to the southwest of the center.
Credit: SSAI/NASA, Hal Pierce
NASA Eyes Power in Tropical Storm Washi, Warnings in the Philippines

NASA's TRMM satellite measured heavy rainfall and powerful towering thunderstorms as Tropical Depression 27W intensified into Tropical Storm Washi today. Now, warnings are up in areas of the Philippines as Washi heads in that direction.

Now that Tropical Depression 27W strengthened into a tropical storm, it has been given two names: Washi and Sendong. Tropical cyclones within each ocean basin are named in six year lists, but some countries will also assign their own names to a storm, so following a storm can get a little confusing. Low pressure areas that form into a depression are given a number and Washi's was 27W, for the twenty-seventh tropical depression in the western North Pacific this season. Once it strengthens into a tropical storm it gets a name.

Tropical Storm Washi, or Sendong as it is known in the Philippines has residents there on guard as it continues to strengthen upon its approach.

The Philippine Atmospheric, Geophysical and Astronomical Services Administration (PAGASA) Weather Forecasting Section, Weather Division is responsible for forecasts of tropical cyclones affecting the Philippines. PAGASA noted in a bulletin today, December 15 at 5 p.m. local time (0900 UTC or 4 a.m. EST): "Tropical Storm 27W (called "Sendong" in the Philippines) is expected to make landfall over Surigao del Sur early tomorrow (Friday) afternoon and by Saturday afternoon, at 220 km East Northeast of Puerto Princesa City. By Sunday afternoon, it will be at 260 km West Northwest of Puerto Princesa City."

As a result of Washi's (Sendong) approach, PAGASA has posted warning signals. Signal One is in effect for Mindanao and Visayas. Mindanao is the second largest and easternmost island of the Philippines. It is one of the three island groups in the country, the others being Luzon and the Visayas.

Included in the warning in Mindanao is the province of Surigao Del Norte including Siargao Island, Surigao Del, Sur and Dinagat Province, Agusan Provinces and Misamis Oriental. Included in the warning in Visayas are the provinces of Eastern Samar and Western Samar, Leyte Provinces, Camotes Island, and Bohol. Heavy rains and gusty winds are expected. Rainfall may cause flooding and mudslides.

On Dec. 15 at 0900 UTC, Tropical Storm Washi had maximum sustained winds near 35 knots (40 mph/65 kmh). It was about 140 nautical miles (161 miles/259 km) west of Palau near 7.7 North and 131.5 East. It was moving quickly to the west at 20 knots (23 mph/37 kmh).

When the Tropical Rainfall Measuring Mission (TRMM) satellite passed over Washi early today, Dec. 15 at 0205 UTC (Dec. 14 at 9:05 a.m. EST) a "hot towering" thunderstorm was seen in the southwestern quadrant of the storm topping 10 miles (16 kilometers) high. Research done at NASA's Goddard Space Flight Center in Greenbelt, Md. has shown that tropical cyclones are likely to intensify within six hours of a "hot tower" being spotted in a tropical cyclone.

Multispectral satellite imagery showed the banding of thunderstorms wrapping into the center of circulation - another indication that the storm is strengthening. The storm is strengthening because the wind shear is light (only 10 knots/11 mph/18 kmh) and the sea surface temperatures are very warm at about 88 degrees Fahrenheit (31 Celsius) which is about 8F warmer than the minimum temperature needed to maintain a tropical cyclone.

The Joint Typhoon Warning Center expects Washi to make landfall on Friday, Dec. 16 and then re-emerge over water in the Sulu Sea. In the meantime, residents of Minandao and Visayas need to prepare for Washi's arrival.

Text credit: Rob Gutro
NASA's Goddard Space Flight Center, Greenbelt, Md.



Dec. 14, 2011

TRMM provided a › View larger image
TRMM provided a "top down" rainfall analysis of Tropical Storm 27W on Dec. 13 at 10:33 a.m. EST. Light to moderate rainfall (green and blue) was falling at a rate between .78 to 1.57 inches/20 to 40 mm per hour northeast and west of the center. The satellite overpass missed the southeastern side of the storm (not shown here).
Credit: SSAI/NASA, Hal Pierce
27W Now a Tropical Storm, NASA Eyes Rainfall from Space

Tropical Depression 27W strengthened into a tropical storm today and is expected to continue strengthening as it makes its way toward the central Philippines. NASA's TRMM satellite analyzed its rainfall rates yesterday and saw moderate rainfall in two quadrants of the storm.

The Tropical Rainfall Measuring Mission (TRMM) satellite saw then tropical depression 27W on December 13, 2011 at 1533 UTC (10:33 a.m. EST). It was upgraded to a Tropical storm by the Joint Typhoon Warning Center (JTWC) the next day, Dec. 14 at 0900 UTC. TRMM's Microwave Imager (TMI) showed that moderate rainfall was located in clusters of strong convective storms within the developing tropical cyclone. The strongest thunderstorms were located to the north of the center of circulation and there were multiple bands of thunderstorms to the south of the center.

On Dec. 14, 2011 at 1500 UTC (10 a.m. EST), Tropical Storm 27W was about 150 nautical miles south of Yap, near 6.9 North latitude and 137.0 East longitude. Yap is an island in the Caroline Islands and is a state of the Federated States of Micronesia. TS27W is moving to the west-northwest at 14 knots (16 mph/26 kmh).

Tropical Cyclones can form in the western Pacific Ocean at any time during the year but they occur most frequently during the months of June through November so tropical storm 27W (TS27W) is a little unusual.

Tropical storm 27W has been predicted to intensify to minimal typhoon strength with winds of 65 knots (~75 mph) before moving over the southern Philippines in the next couple days. In a typical year 6-9 tropical cyclones cross over the Philippines. This year has been unusually deadly with typhoons Nesat and Nalgae causing heavy flooding and loss of life in the Philippines in late September and early October.

Text credit: Hal Pierce/Rob Gutro
SSAI/NASA's Goddard Space Flight Center, Greenbelt, Md.



Dec. 13, 2011

visible light satellite image of TD27W › View larger image
The MODIS instrument on NASA's Aqua satellite captured this visible image of Tropical Depression 27W on Dec. 13 at 0416 UTC (Dec. 12 at 11:16 p.m. EST). TD27W is about 415 miles south of Andersen Air Force Base, Guam. Credit: NASA/NRL
Another New Tropical Depression Forms in Western North Pacific

Tropical Depression 27W formed in the western North Pacific Ocean today, on the heels of Depression 26W, which is now fading.

Tropical Depression 27W (TD27W) formed at 0900 UTC (4 a.m. EST) and by 1500 UTC (10 a.m. EST) was located about 415 miles south of Andersen Air Force Base, Guam. It was centered near 6.4 North latitude and 143.3 East longitude moving to the west-northwest near 18 knots (20 mph/33 kmh). TD27W's maximum sustained winds were near 30 knots (34 mph/55 kmh).

The Moderate Resolution Imaging Spectroradiometer (MODIS) instrument on NASA's Aqua satellite captured a visible image of Tropical Depression 27W on Dec. 13 at 0416 UTC (Dec. 12 at 11:16 p.m. EST). The strongest thunderstorms appeared around the center of circulation. Those were also the highest thunderstorms, and they cast shadows on the surrounding lower clouds. An area of central dense overcast has developed over the low-level center of circulation that is about 120 nautical miles in diameter. The forecasters at the Joint Typhoon Warning Center noted that 27W is in an area of low wind shear, which will allow it to strengthen.

The Joint Typhoon Warning Center noted that TD27W threatens to bring parts of the Philippines gusty winds and heavy rainfall. TD27W is expected to intensify to typhoon strength as it moves toward Mindanao. Currently, a tropical storm watch is posted for Koror and Kayangel in Palau, and Ngulu in Yap.

Text credit: Rob Gutro
NASA's Goddard Space Flight Center, Greenbelt, Md.