Typhoon Omar

Super Typhoon Omar (Lusing)
Typhoon (JMA scale)
Category 4 (Saffir–Simpson scale)
Typhoon Omar 29 aug 1992 2154Z.jpg
Typhoon Omar between Guam and Taiwan at peak intensity on August 29
Formed August 23, 1992 (August 23, 1992)
Dissipated September 9, 1992 (September 9, 1992)
Highest winds 10-minute sustained: 185 km/h (115 mph)
1-minute sustained: 240 km/h (150 mph)
Lowest pressure 920 hPa ( mbar); 27.17 inHg
Fatalities 15 total
Damage $561.2 million (1992 USD)
Areas affected Guam, Philippines, Ryukyu Islands, Taiwan, China, Vietnam
Part of the 1992 Pacific typhoon season

Typhoon Omar of 1992, known in the Philippines as Typhoon Lusing, [1] was the strongest and costliest typhoon to strike Guam since Typhoon Pamela in 1976. The cyclone formed on August 23 from the monsoon trough across the western Pacific Ocean. Moving westward, Omar slowly intensified into a tropical storm, although another tropical cyclone nearby initially impeded further strengthening. After the two storms became more distant, Omar quickly strengthened into a powerful typhoon. On August 28, it made landfall on Guam with winds of 195 km/h (120 mph). The typhoon reached its peak intensity the next day, with estimated 1‑minute winds of 240 km/h (150 mph), making it a "super typhoon" according to the Joint Typhoon Warning Center (JTWC). [nb 1] Omar weakened significantly before striking eastern Taiwan on September 4, proceeding into eastern China the next day and dissipating on September 9.

On Guam, Omar caused one death and $457 million (1992  USD) in damage. [nb 2] Strong gusts up to 248 km/h (154 mph) left nearly the entire island without power for several days. The outages disrupted the water system and prevented the island-based JTWC from issuing advisories for 11 days. Omar damaged or destroyed 2,158 houses, leaving 3,000 people homeless. In response to the destruction, the island's building codes were updated to withstand winds of 250 km/h (155 mph), and insurance companies discontinued new policies for structures not made of concrete. While passing well north of the Philippines, the typhoon killed 11 people and wrought ₱903 million ($35.4 million) worth of damage to 538 houses. Omar then brushed the southern islands of Japan with strong gusts and light rainfall, causing ¥476 million JPY ($3.8 million USD) in crop losses. In Taiwan, scattered flooding caused three deaths and $65 million in damage, mostly to agriculture.

Meteorological history

Track of Typhoon Omar plotting its intensity at six-hour intervals. The track begins over the open Pacific Ocean near Kiribati and extends generally west-northwest, ultimately crossing Taiwan and eastern China before ending over northern Vietnam.
Map plotting the track and intensity of the storm, according to the Saffir–Simpson scale

Typhoon Omar originated from a tropical disturbance that was first noted on August 20 over the open Pacific Ocean, which exhibited persistent convection, or thunderstorms. During this early phase, two tropical cyclones dissipated and another became extratropical across the western Pacific basin; this caused the monsoon trough, which spawned most of the storms in the basin, to realign in a more climatologically appropriate manner. [2] According to the Japan Meteorological Agency (JMA), Omar developed into a tropical depression at 1800  UTC on August 23. [4] The Joint Typhoon Warning Center (JTWC) assessed a slower pace of strengthening, issuing a tropical cyclone formation alert at 2100 UTC before initiating advisories on Tropical Depression 15W on August 24. [2]

As the depression traveled generally westward, the JTWC upgraded it to Tropical Storm Omar on August 25, [2] and the JMA followed suit on the next day. [4] Omar began to slow as it tracked westward. Outflow from nearby Tropical Storm Polly to the west produced a stream of strong wind shear over Omar, slowing intensification. The JTWC noted that the shear could decouple Omar's wind circulation from its convection, possibly weakening the storm. However, as Omar and Polly moved farther apart, a high-pressure ridge developed between the storms. This caused Omar to drift northward and then west-northwestward into a region with decreased shear, which allowed it to resume strengthening. Early on August 27, the JTWC upgraded the system to a typhoon, and an eye began to appear around 23:00 UTC that day. [5] Omar entered a phase of rapid intensification on August 28, [2] at which point the JMA also classified it as a typhoon. [4] The typhoon made landfall on Guam soon after, with 1‑minute sustained winds of about 195 km/h (120 mph). [2] The eye, 37 km (23 mi) in diameter, [2] slowly crossed the northern portion of the small island over a period of 2.5 hours. [5]

At 1800 UTC on August 29, Omar reached its peak intensity with 10‑minute sustained winds of 185 km/h (115 mph) and a minimum barometric pressure of 920  mbar ( hPa; 27.17  inHg) as estimated by the JMA; this intensity was maintained for 24 hours before a steady weakening trend began. [4] The JTWC estimated higher 1‑minute winds of around 240 km/h (150 mph), making Omar a super typhoon. [2] Two days later, the typhoon came close enough to the Philippines to warrant monitoring from PAGASA, [nb 3] who named the storm Lusing. [1] By 1500 UTC on September 3, the JMA downgraded Omar to a tropical storm, [4] although the JTWC maintained its typhoon intensity through the next day. [2] Heading generally westward, the storm made landfall on the east coast of Taiwan near Hualien City on September 4. [6] After traversing the island in seven hours, Omar exited the coast of Yunlin County and emerged into the Taiwan Strait. [7] The storm crossed the body of water and moved ashore in eastern China near Xiamen, Fujian, on September 5. [6] Inland, Omar quickly degenerated into a tropical depression before turning west-southwest. It proceeded across southern China while heavily weakening, and completely dissipated over northern Vietnam on September 9. [4]

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Nederlands: Tyfoon Omar