Typhoon Choi-Wan Triggers Tropical Storm Warnings
Microwave imagery from NASA’s Aqua satellite revealed extremely high thunderstorms in Typhoon Choi-Wan as it began passing the island of Sai-Pan in the Western Pacific Ocean. The U.S. National Weather Service has already issued a tropical storm warning and a typhoon watch for Tinian, Saipan and Agrihan in the Northern Mariana Islands.
Saipan is the largest island and capital of the U.S. Commonwealth of the Northern Mariana Islands. The Northern Marianas are a chain of 15 tropical islands belonging to the Marianas archipelago in the western Pacific Ocean. In the year 2000, the island chain was home to more than 62,000 residents. The National Weather Service issues advisories for them, because they are a U.S. Commonwealth.
NASA satellite imagery showed that the tops of the thunderstorms are so high they reached the tropopause, the level of atmosphere between the troposphere and stratosphere. Those high thunderstorms mean very heavy rainfall for the area underneath. The cloud tops extended to the 200 millibar level in the atmosphere where temperatures are as cold or colder than -63 Fahrenheit.
Microwave images are created when data from NASA’s Aqua satellite Atmospheric Infrared Sounder (AIRS) and Advanced Microwave Sounding Unit (AMSU) instruments are combined. These microwave images indicate where there is precipitation or ice in the cloud tops and the latest microwave image revealed Choi-Wan had cold, high thunderstorms.
On August 14 at 11 a.m. EDT, Choi-Wan was located 105 miles east-northeast of Saipan, near 16.2 north and 147.3 east. It was moving northwest near 5 mph. The storm has intensified over the last six hours in an area with warm waters and low wind shear. Choi-Wan’s maximum sustained winds were near 90 mph and those winds were kicking up very high waves, as high as 29 feet. The typhoon is expected to pass north of Saipan Tuesday morning.
Residents of Saipan is already experiencing gusty winds and rains as the Choi-Wan passes to the northeast, and dangerous surf is expected along the shorelines. For a look at local radar from Andersen Air Force Base, Guam: http://forecast.weather.gov/MapClick.php?zoneid=GUZ004.
Text credit: Rob Gutro, NASA/Goddard Space Flight Center
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Image 1: NASA’s AIRS instrument captured this impressive image of Typhoon Choi-Wan on September 14 at 11:05 p.m. EDT. The white area is outside the view of the satellite instrument as it passed over the storm from space. Credit: NASA/JPL, Ed Olsen
Image 2: NASA’s Aqua satellite AIRS and AMSU instrument data created a microwave image of Choi-Wan on September 13 at 2:11 p.m. EDT. The cold areas in this image (yellow-green) that stretch from right center, left of the small chain of islands, indicate where there is precipitation or ice in the cloud tops. The purple area (far right) has the coldest cloud temperatures to -63F and suggests cloud heights to the 200 millibar level, near the tropopause. Credit: NASA/JPL, Ed Olsen
