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Hurricane Season 2011: Tropical Storm Nalgae (Northwest Pacific Ocean)
10.05.11
 
This TRMM image shows only scattered areas of light to moderate rainfall were present with Nalgae › View larger image
This TRMM satellite rainfall image shows only scattered areas of light to moderate rainfall (green and blue, falling at a rate between .78 to 1.57 inches/20 to 40 mm per hour) were present with Nalgae as it moved into the Gulf of Tonkin west of Hainan Island.
Credit: NASA Earth Observatory/TRMM/NASA Goddard/Jesse Allen
NASA Eyes Light Rainfall in Dissipating Tropical Depression Nalgae

Tropical Depression Nalgae weakened rapidly when it made landfall on Hainan Island, China yesterday and NASA's TRMM satellite observed lighter rainfall rates that coincided with its lower intensity. Today, Nalgae's remnants are moving drifting toward Vietnam.

TRMM measured the rainfall rates in Nalgae on October 4, 2011 at 0624 UTC (2:24 a.m. EDT). The rainfall analysis from TRMM's Microwave Imager (TMI) and Precipitation Radar (PR) showed only scattered areas of light to moderate rainfall were present with Nalgae as it moved into the Gulf of Tonkin west of Hainan Island. Rain was falling at a rate between .78 to 1.57 inches/20 to 40 mm per hour.

By October 5 at 1500 UTC (11 a.m. EDT), Nalgae had weakened into a remnant low pressure area with maximum sustained winds of 20 knots (23 mph/37 kmh) around its circulation center. It was located about 100 nautical miles north of Hue, Vietnam near 18.0 North and 107.3 East. The remnant low was drifting to the west-southwest at 2 knots (2 mph/4 kmh).

The forecasters at the Joint Typhoon Warning Center noted that the movement across Hainan Island weakened the system beyond the point of regeneration. There was no convection (rising air that forms thunderstorms that make up a tropical depression) evident today, Oct. 5. The remnant low is drifting to the coast today.

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



This image shows average rainfall totals in the Western Pacific from September 26 to October 2, 2011 › View larger image
This image shows average rainfall totals in the Western Pacific from September 26 to October 2, 2011, when Typhoon Nesat and Super Typhoon Nalgae passed through. The heaviest average rainfall—more than 350 millimeters or 14 inches—appears in dark blue. Localized rainfall amounts could be significantly higher. The lightest rainfall—less than 50 millimeters or 2 inches—appears in light green.
Credit: NASA Earth Observatory/TRMM/NASA Goddard/Jesse Allen
Typhoons Nesat and Nalgae Soak The Philippines

In a matter of five days, the Philippines and southeastern Asia were hammered by two intense tropical storms in late September and early October 2011. Several months worth of rain fell within a week—a deluge even by tropical standards—on Luzon in the northern Philippines, as well as in northern Vietnam and the Chinese island of Hainan.

This image shows average rainfall totals in the Western Pacific from September 26 to October 2, 2011, when Typhoon Nesat and Super Typhoon Nalgae passed through. The heaviest average rainfall—more than 350 millimeters or 14 inches—appears in dark blue. Localized rainfall amounts could be significantly higher. The lightest rainfall—less than 50 millimeters or 2 inches—appears in light green.

Superimposed on the rainfall totals are the storm tracks for Nesat and Nalgae, with maroon indicating the strongest storm intensity, and pink indicating the weakest. Typhoon Nesat reached category 3 strength, with winds estimated at 105 knots (120 miles/195 kilometers per hour) late on September 26, 2011, when it crossed into the heavily populated island of Luzon, Philippines. The storm weakened, but still maintained typhoon winds when it reached Hainan on September 29.

Nalgae was a category 4 super typhoon when it made landfall in the Philippines on October 1, with winds approaching 130 knots (150 miles/240 kilometers per hour). The storm was downgraded to tropical storm force, but was still approaching Hainan and Vietnam on October 3.

According to news reports, almost three million Filipinos were affected by the storms. At least 58 people were killed and another 28 were missing as of October 3. More than 300,000 people were being housed in evacuation centers, and damage estimates were approaching 8.8 billion pesos ($200 million U.S.). In southern China, roughly 140,000 people were evacuated, losses approached 1.6 billion yuan ($ 251 million U.S.), and at least four people were killed.

This image is based on data from the Multisatellite Precipitation Analysis (MPA) produced at NASA's Goddard Space Flight Center. The MPA estimates rainfall by combining measurements from many satellites and calibrating them against rainfall measurements from the Tropical Rainfall Measuring Mission (TRMM) satellite.

Text credit: Michael Carlowicz
NASA Earth Observatory
NASA/Goddard Space Flight Center, Greenbelt, Md.



October 4, 2011

MODIS captured a visible image of Typhoon Nalgae over the Philippines on Oct. 1 at 03:00 UTC. › View larger image
The Moderate Resolution Imaging Spectroradiometer instrument on NASA's Terra satellite captured a visible image of Typhoon Nalgae over the Philippines on Oct. 1 at 03:00 UTC.
Credit: NASA Goddard MODIS Rapid Response Team
TRMM satellite had a good look at typhoon Nalgae on 2 October 2011 at 0637 UTC › View larger image
The TRMM satellite had a good look at typhoon Nalgae on 2 October 2011 at 0637 UTC after it became the second typhoon in a week to hit the Philippines. This TRMM image shows rainfall in Nalgae after it passed the Philippines and headed toward China. Heaviest rain (2 inches/50 mm per hour) appears in red. Moderate to light rainfall appears in green and blue, falling at a rate between .78 to 1.57 inches (20 to 40 mm) per hour.
Credit: NASA/SSAI, Hal Pierce
Nalgae Now a Depression Over Hainan Island, China

After making landfall on Hainan Island, China, Tropical Storm Nalgae weakened to a tropical depression, and rainfall rates have slowed as a result of the rugged terrain. Before landfall, NASA's TRMM satellite saw two large areas of heavy rainfall.

On October 2, Nalgae was in the middle of the South China Sea headed toward southern Hainan. In an image from the Tropical Rainfall Measuring Mission (TRMM) satellite, a rainfall analysis from TMI and PR data was overlaid on a combination Infrared and Visible image from TRMM's Visible and InfraRed Scanner (VIRS) instrument. That analysis showed large areas of heavy rainfall in bands of thunderstorms to the north and south of the center of circulation.

After Nalgae made landfall, the rugged terrain put an end to the deep convection and adversely affected the tropical cyclone. NASA Infrared imagery from the Aqua satellite revealed, today, October 4, that cloud tops in the thunderstorms that make up Nalgae warmed, and dropped in height and strength. Hainan Island reported an increase of 4 millibars of atmospheric pressure today, indicating the storm was weakening.

Nalgae was a tropical depression centered over Hainan Island and moving into the Gulf of Tonkin. Nalgae is on a westward track and headed toward another landfall in Vietnam. It is moving west at 11 knots (13 mph/20 kmh). Nalgae's maximum sustained winds are down to 30 knots (35 mph/55 kmh) but is expected to briefly re-intensify into a tropical storm before making landfall in Vietnam tomorrow.

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















September 29, 2011

TRMM saw moderate rainfall occurring in Nalgae on Sept 28, 2011 at 15:21 UTC (11:21 a.m. EDT). › View larger image
NASA's TRMM satellite saw moderate rainfall occurring on Nalgae on Sept 28, 2011 at 15:21 UTC (11:21 a.m. EDT). The moderate to light rainfall (green and blue) was falling at a rate between .78 to 1.57 inches (20 to 40 mm) per hour.
Credit: NASA/SSAI, Hal Pierce
NASA Measures Moderate Rainfall in Strengthening Typhoon Nalgae

Typhoon Nalgae has grown from a depression to a tropical storm into a full-fledged typhoon within three days. That's a continuous increase in strength since birth. Two NASA satellites have been monitoring Nalgae's growth and increasingly cold cloud temperatures and rainfall as it continues to mature.

NASA's Tropical Rainfall Measuring Mission (TRMM) satellite passed over Nalgae on Sept. 28, 2011 at 15:21 UTC (11:21 a.m. EDT) and noticed moderate to light within the storm. Rain was falling at a rate between .78 to 1.57 inches (20 to 40 mm) per hour. As Nalgae has matured into a tropical storm and then a typhoon, rainfall rates have increased.

NASA's Aqua satellite takes infrared data of tropical cyclones from the Atmospheric Infrared Sounder (AIRS) instrument. In an infrared image on Sept. 29 at 12:35 a.m. EDT, Typhoon Nalgae had a large area of very cold clouds, and strong thunderstorms surrounding its center of circulation. That indicates that the typhoon's heat engine is working hard. Those cloud top temperatures exceeded -63 Fahrenheit (-52 Celsius). Infrared imagery shows that Nalgae continued to consolidate with tightly-curved banding wrapping into its well-defined center. Visible data from the AIRS instrument revealed that Nalgae is also taking on the signature shape of a mature typhoon.

At 11 a.m. EDT on Sept. 29, Typhoon Nalgae had maximum sustained winds near 70 knots. It was centered about 645 east-northeast of Manila, Philippines, near 17.8 North and 131.1 East. It has tracked west-southwestward at 13 knots and is generating maximum wave heights of 20 feet.

The Joint Typhoon Warning Center forecasters expect Nalgae to continue strengthening on its western track toward the Philippines. Nalgae is expected to make landfall over extreme northern Luzon, Philippines on Oct. 1, then move into the South China Sea for a landfall in Vietnam next week.

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



September 28, 2011

This visible image of Tropical Storm Nalgae was captured  on Sept. 28 at 03:53 UTC. › View larger image
This visible image of Tropical Storm Nalgae was captured by the AIRS instrument on NASA's Aqua satellite on Sept. 28 at 03:53 UTC.
Credit: NASA/JPL, Ed Olsen
NASA Satellite Sees Tropical Storm Nalgae Take on the Comma Shape

A comma shape is a typical shape that mature tropical storms and hurricanes take on, and NASA's Aqua satellite noticed that Tropical Storm Nalgae in the western Pacific Ocean has now matured to that shape.

The Atmospheric Infrared Sounder instrument that flies on Aqua, took a visible image of Tropical Storm Nalgae on Sept. 28 at 03:53 UTC. In addition to the comma shape the storm has taken on, the AIRS instrument provided a look at cloud-top temperatures, which are an indication of where the strongest storms and heaviest precipitation is falling. The coldest cloud top temperatures (colder than -63F/-52C) were north, west and south of the center of circulation. The infrared data also showed tightly curved bands of thunderstorms wrapping into the low-level center of circulation, indicating the storm is organizing further. Microwave satellite imagery already indicates that an eye has formed.

Tropical storm Nalgae formed from Tropical Depression 22 when it strengthened overnight. Today, Sept. 28, 2011 at 0900 UTC (5 a.m. EDT), Nalgae had maximum sustained winds near 50 knots. Tropical Storm Nalgae is about 180 miles in diameter as tropical-storm-force winds extend as far as 90 miles from the center.

The forecasters at the Joint Typhoon Warning Center (JTWC) noted that the warm sea surface temperatures ahead of Nalgae will enable it to strengthen. Those sea surface temperatures were also seen by the infrared AIRS image. JTWC forecasts that Nalgae will become a typhoon by the time it reaches northern Luzon, Philippines around the first of October.

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



September 27, 2011

Tropical Depression 22W formed in the NW Pacific, and some of the rain was falling at 2 inches (50 mm) per hour (red). › View larger image
Tropical Depression 22W formed in the NW Pacific, and some of the rainfall was occurring in its southeastern quadrant was falling at 2 inches (50 mm) per hour (red). Around the rest of the storm was mostly moderate to light rainfall (green and blue) between .78 to 1.57 inches (20 to 40 mm) per hour.
Credit: NASA/SSAI, Hal Pierce
NASA Sees 22nd Tropical Depression Form in NW Pacific

The western North Pacific Ocean has been very active this year, and NASA's TRMM satellite has seen the twenty-second depression form there today.

NASA's Tropical Rainfall Measuring Mission satellite known as TRMM passed over Hilary on Sept. 27 at 12:17 p.m. EDT and its precipitation radar instrument measured rainfall happening throughout the storm from its orbit in space. TRMM saw that most of the rainfall occurring was moderate, with the exception of the southeastern quadrant. In that area, rain was coming down at 2 inches/50 mm per hour.

TRMM also has the ability to measure cloud heights, which indicate the power within a hurricane. The higher the towering clouds around the eye, usually the stronger the power within the hurricane. TRMM noticed that the highest cumulonimbus (thunderstorm) clouds in the center were around 15 kilometers (~9.3 miles). Towering clouds that height are indicative of a lot of power in the storm.

Even infrared imagery is showing that the storm is consolidating, and bands of thunderstorms are wrapping around the center. That's a sign that the storm is getting organized and strengthening. There is a strong band of thunderstorms to the south of the center of circulation, where the TRMM satellite measured the heaviest rainfall.

22W's maximum sustained winds were near 25 knots (29 mph/46 kmh). It was located about 700 nautical miles southeast of Kadena Air Base, Japan. 22W is moving to the northwest near 3 knots (4 mph/6 kmh).

The Joint Typhoon Warning Center currently forecasts Tropical Depression 22W to make landfall by October 2nd in northern Luzon, Philippines, following in the footsteps of Typhoon Nesat.

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