Possible direct hit on Agrihan and Alamagan islands
Posted by JAC on 9/15/2009, 1:05 pm
Choi-Wan is an extremely dangerous Category Four typhoon on the Saffir-Simpson Scale, and is expected to strengthen to a Category Five storm later today. NASA's Terra satellite revealed that Choi-Wan had a very clear eye as it passed overhead late last night, indicating a strong, well-organized typhoon.

The islands of Agrihan and Alamagan in the Western Pacific lay Choi-Wan's path today and a typhoon warning is in effect for Agrihan, while a tropical storm warning remains in effect for Saipan. Dangerous and powerful winds near 130 mph are expected today and tonight (local time) in Agrihan and Alamagan.

On Tuesday, September 15 at 11 a.m. EDT (that's Wednesday, September 16 at 1 a.m. local time, as they're 14 hours ahead of the U.S. East Coast) Super typhoon Choi-wan had maximum sustained winds near 155 mph. That's the border of a Category Four and Category Five Typhoon (Hurricane). Sustained winds in excess of 155 mph are classified as a Category Five. Choi-Wan's center was approximately 175 nautical miles north-northwest of Saipan near 18.2 north 144.7 east, and the storm has tracked west-northwestward at 9 mph. Choi-wan is creating huge waves, up to 38 feet high.

NASA's Terra satellite flew over Super Typhoon Choi-Wan late last night at 8:45 p.m. EDT (10:45 a.m. local time this morning), and the Moderate Imaging Spectroradiometer (MODIS) instrument captured a clear eye in this well developed cyclone.

The National Weather Service forecast office that covers the U.S. Territory noted in their forecast today, "Residents of Agrihan and Alamagan islands should be prepared for the possibility of a direct hit from typhoon Choi-wan this afternoon or evening...with winds rising to well over 100 mph possible. Preparations to protect life and property should be completed as soon as possible. Remain in a safe shelter throughout the storm."

The National Weather Service's local warning states: "Winds at Agrihan and Alamagan will rise to typhoon force this afternoon...and winds of 130 mph or higher are possible late this afternoon or evening if the eye of Choi-wan makes a direct hit. Such winds would be life-threatening and result in near-total property damage. For Agrihan and Alamagan...a storm surge of 12 feet or more is possible as Choi-wan passes this afternoon and tonight. "

At Saipan a storm surge of 1 to 3 feet above high tide is possible...with hazardous surf of 8 to 11 feet along west facing reefs this evening...building to 12 to 15 feet tonight. High tide is expected around 6 pm today...which is around the time of closest approach to Alamagan. In addition, Guam, Rota and Tinian are under a High Surf Advisory until 6 p.m. CHST Thursday, September 17. High surf will affect exposed reefs and beaches in the advisory area producing dangerous rip currents. Surf will be 10 to 12 feet on west facing exposures and 8 to 10 feet on south facing exposures tonight through Thursday.

Heavy rainfall is expected through Wednesday with storm totals of 3 to 5 inches possible at Saipan and as much as 6 to 10 inches at Alamagan and Agrihan.

Choi-wan is still moving northwest while intensifying. It is expected to reach Category Five status on the Saffir-Simpson Scale.

Text credit: Rob Gutro, NASA/Goddard Space Flight Center
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Super Typhoon Choi-Wan (ADT at Cat5) - JAC, 9/15/2009, 7:38 am
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