Typhoon Season is around the corner: It's time to get ready again
By Master Sgt. Mark Gustilo, 36th Operations Support Squadron
/ Published May 28, 2008
ANDERSEN AIR FORCE BASE, Guam -- The Northwest Pacific is the most active breeding ground for tropical cyclone activity on earth. On an annual average, 31 tropical cyclones form in the Northwest Pacific Ocean, with about 18 to 20 of them reaching typhoon strength. . In comparison to the storms affecting the East and Gulf Coast of the U.S., the number of storms in the Pacific Northwest is roughly three times higher than the yearly average number of cyclones that form in the Atlantic Ocean.
A cyclone is a broad term used by meteorologists to highlight a counter clockwise, rotating region of low pressure in the northern hemisphere. "Tropical" cyclones are cyclones located in the tropical regions and are classified into four different categories based on the maximum center wind speeds they produce. By ascending intensities, the four tropical cyclone categories are: tropical depression (center winds up 25 to 34 knots), tropical storm (34 to 63 knots), typhoon (64 to 129 knots), and super typhoon (center winds 130 knots and greater).
In reality, there are no physical differences between a hurricane and a typhoon - just where they form and exist. Storms on the east side of the International Date Line are labeled hurricanes while storms on the west side are labeled typhoons. As far as which system is stronger, hurricanes and typhoons are basically the same tropical systems possessing similar intensities. Occurrence-wise, typhoons tend to be more frequent in nature due to the larger area of the Pacific Ocean available for tropical cyclone development.
A catalyst and energy source for tropical cyclone formation is warm ocean water (typically 81 degrees Fahrenheit and greater). Historically, the large warm waters of the Central and Northwestern Pacific Ocean serve as favorable breeding grounds for these tropical systems. Unfortunately, Guam is situated in an area referred to as "Typhoon Alley", which is a typhoon-susceptible region bounded by Guam, the Philippines and Japan. During the typhoon season, tropical cyclones have a climatological tendency to form in the central/western regions of the Pacific then track westward across Typhoon Alley as tropical storms or typhoons.
For Guam, tropical storms and typhoons can occur anytime of the year, though a typical typhoon season for Guam runs from late June through December (when Pacific Ocean the water temperatures are at their warmest), with the peak of the typhoon season occurring between late August through mid-November. It is during these peak season months that typhoons pose the greatest threat to Guam. Here are a few, notable typhoons that directly and significantly impacted Guam: Super-Typhoon Karen (Nov 1962, max wind on Guam: 160kts/184mph), Super-Typhoon Pamela (May 1976, max wind on Guam: 145kts/167mph), Typhoon Omar (Aug 1992, max wind on Guam: 130kts/150mph), Super-Typhoon Paka (Dec 1997, max wind on Guam: 160kts/184mph) and finally Super-Typhoon Pongsona (Dec 2002, max wind on Guam: 150kts/173mph)
As we enter this year's typhoon season, you are encouraged to review TCOR (Typhoon Condition of Readiness) postures and response actions to include taking inventory of your typhoon survival kits. Be advised, when a tropical storm or typhoon threatens Guam, availability of emergency supplies may become limited in a short span of time. Due to their unpredictable nature, some tropical storms or typhoons could develop close to Guam and give us only a 72-hour notice before the onset of destructive winds (in excess of 56 mph or 49 knots) - one good reason why we remain in TCOR 4 year-round.
Familiarization with TCOR conditions and actions will pay off greatly during typhoon situations. When a tropical storm or typhoon approaches Guam, our fair weather pattern gradually takes a turn for the worse as stormy weather conditions including gusty winds, cloudy skies and increased rain showers prevail. During typhoon impact, expect up to 24 hours of destructive winds, heavy rains, scattered thunderstorms, flooding in low-lying areas, falling trees, flying debris and possible tornadoes. Disruption of utility services (e.g. electricity) may occur as early as storm onset and last up to hours (or sometimes days and even weeks) after typhoon passage. Preparation and readiness is key when living in Typhoon Alley, and always remember, it's never too early to prepare for typhoons on Guam.