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Hurricane Season 2009: Tropical Storm 18W (Western Pacific)
09.30.09
 
September 30, 2009

Typhoon Parma (left) and Tropical Depression 18W (right). > View larger image

This NASA infrared AIRS satellite image from September 30 at 1:11 a.m. (Guam local time) shows the cloud top temperatures of Typhoon Parma (left) and Tropical Depression 18W (right). Highest clouds with temperatures as cold as -63F indicating strong thunderstorms appear in purple. 18W dissipated hours after this image. Credit: NASA/JPL, Ed Olsen
Typhoon Parma with a very organized cloud structure, indicating strengthening. > View larger image
This visible image from NASA's Aqua satellite AIRS instrument on September 30 at 12 a.m. EDT shows Typhoon Parma with a very organized cloud structure, indicating strengthening.
Credit: NASA/JPL, Ed Olsen
Come Together, Right Now … Tropical Depression 18W Dissipates, Parma Intensifies

Two tropical cyclones in the Western Pacific are keeping in tune to the 1969 hit song by the Beatles, "Come Together." Tropical Depression 18W and Tropical Storm Parma are already beginning to merge now that 18W made landfall in Guam and dissipated. 18W did bring gusty winds and heavy downpours to Guam, and will continue to affect the surf over the next day or two.

NASA's Aqua satellite flew over the two storms and captured them in one image (because they're close to each other). Parma is located west of 18W's remnants. The Atmospheric Infrared Sounder (AIRS) instrument on Aqua noticed high thunderstorms in Parma as cloud top temperatures were colder than -63 Fahrenheit, and Parma intensified into a typhoon. In 18W, satellite data showed warmer cloud top temperatures, indicating a much weaker system. AIRS captured an image of both storms on September 30 at 1:11 a.m. (Guam local time).

At 11 a.m. local time on September 30, 18W's center was 85 miles east-southeast of Guam. At that time, it had not yet made landfall and was headed toward Guam (Guam is 14 hours ahead of U.S. Eastern Daylight Time). 18W then made landfall in Guam in the afternoon hours (local time) on September 30, and has since weakened into a remnant low pressure area.

The U.S. Navy's Joint Typhoon Warning Center issued its final warning on 18W at 7 p.m. local time (5 a.m. EDT) today, after 18W had made landfall and crossed back into the Western Pacific Ocean. At that time, 18W's center 55 miles west-northwest of Guam, near 13.9 north and 144.0 east and its maximum sustained winds were down to 15 knots (17 mph). 18W's remnants were moving west-northwest near 21 knots (24 mph). That's going to bring the remnants toward Tropical Storm Parma quickly, causing Parma to absorb 18W's leftover energy.

At 7:30 p.m. Guam local time (9:30 a.m. EDT) on September 30 there were High Surf Warnings up for Guam, the Marianas Islands, and Micronesia until 6 p.m. (local time) on Thursday. The National Weather Service noted, "Large swells generated by tropical storm 18w before it weakened to a tropical depression will generate high surf on east facing reefs through Thursday afternoon. A high surf advisory means that high surf will affect exposed reefs and beaches in the advisory area producing dangerous rip currents. Expect hazardous surf of 10 to 12 feet Thursday on east facing reefs. The surf should subside below hazardous levels by Thursday evening."

Guam also posted a Small Craft Advisory in effect until 6 p.m. CHST (local time, Guam) on Thursday. A small craft advisory means that seas 10 feet or greater and sustained winds or frequent gusts of 22 knots (25 mph) or higher are expected to produce conditions hazardous to small craft.

As 18W dissipated, Tropical Storm Parma intensified into a typhoon. Typhoon Parma is located to the west of 18W's remnants, but close enough to draw its leftover energy.

On September 30 at 11 a.m. EDT (3 a.m. local time on October 1), Typhoon Parma had sustained winds near 75 knots (86 mph) and was moving west-northwest near 15 knots (17 mph). It was located about 160 miles north-northwest of the island of Palau. Tropical storm-force winds stretch out to 75 miles from the center, while typhoon/hurricane-force winds extend only 10 miles from the center. Meteorologists at the Philippine Atmospheric Geophysical and Astronomical Services Administration (Pagasa) are calling Typhoon Parma "Pepeng" in the Philippines.

On the current forecast track, Typhoon Parma will not make landfall in the northern Philippines, but its center will remain at sea as it passes to the northeast over the next several days. Because residents of the northern Philippines are still coping with the floodwaters generated from Tropical Depression Ondoy (Ketsana), another tropical cyclone is the last thing they need.

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



September 29, 2009

Tropical Storm Parma (left) and Tropical Storm 18W (right) on September 29 at midnight EDT. > View larger image
NASA's Aqua satellite AIRS instrument captured an infrared image of Tropical Storm Parma (left) and Tropical Storm 18W (right) on September 29 at midnight EDT. The purple areas indicate the highest thunderstorm cloud tops as cold as -63 Fahrenheit.
Credit: NASA/JPL, Ed Olsen
Tropical Depression 19W Becomes Tropical Storm Parma, 18W Struggling

It's getting hard to keep score with tropical cyclones in the Western Pacific this week as four of them are swirling around. Forecasters have noticed that Tropical Depression 19W has now strengthened into a tropical storm, and have given it the name "Parma."

Tropical Storm Parma had sustained winds near 52 mph at 11 a.m. EDT on Tuesday, September 29. Tropical Storm Parma is moving west-northwest near 8 mph, and is generating 17-foot high waves. It was centered about 90 miles south of the island of Yap, near 8.0 north latitude and 138.2 east longitude. Yap, also known as Wa'ab for locals, is an island in the Caroline Islands of the western Pacific Ocean. It is a state of the Federated States of Micronesia. A tropical storm warning is in force for Yap and Ngulu (one of 14 atolls in the State of Yap).

Meanwhile, Tropical Storm 18W is a weak tropical storm with maximum sustained winds near 40 mph, but they won't last long because of Tropical Storm Parma's influence. Tropical Storm 18W (still un-named) was located near 11.9 north and 148.9 north, southeast of Guam. It was moving west-northwest near 21 mph.

NASA's Aqua satellite AIRS instrument captured an infrared image of both Tropical Storm Parma and Tropical Storm 18W (east of Parma) on September 29 at midnight EDT. AIRS infrared imagery measures temperatures in the clouds, and found some of the highest thunderstorm cloud tops were cold as -63 Fahrenheit, indicating some strong convection in each. There was a greater amount of strong convection in Parma than 18W, however.

Tropical Storm Parma is forecast to move west, then northwest and intensify. As Parma moves northwestward, Tropical Depression 18W is forecast to begin to be absorbed into Tropical Storm Parma in the next several days.

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



September 28, 2009

AIRS image of Tropical Depression 18W on September 28, 2009 › View larger image
NASA's Aqua satellite flew over Tropical Depression 18W on September 28 at 3:11 UTC and the AIRS instrument captured this visible image.
Credit: NASA/JPL, Ed Olsen
Tropical Depressions 18W and 19W Form In the Western Pacific

Two tropical depressions formed 450 miles apart from each other in the last 24 hours in the Western Pacific Ocean. Tropical Depression 18W (TD18W) is expected to strengthen as it moves towards Guam. Tropical Depression 19W (TD19W) is expected to move through Micronesia, then move northwest toward Taiwan.

Because both storms are close together, forecasting their paths is a challenge because they may interact.

TD 19W was located 235 miles south of Guam, near 9.3 north and 144.1 east during the morning hours (Eastern Daylight Time) on September 28. TD18W was located 630 miles east-southeast of Guam near 9.1 north and 154.8 east. Both had maximum sustained winds near 35 mph.

NASA's Aqua satellite flew over the TD18W on September 28 at 3:11 UTC (September 27 at 11:11 p.m. EDT) and captured an image of its cloud cover, which appeared disorganized.

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