User:TheAustinMan/sandbox/Meteorological history of Typhoon Haiyan (2013)

Typhoon Haiyan's meteorological history began with its origins as an area of disturbed weather near Pohnpei on November 2 and lasted until its dissipation inland over southwestern China on November 12. Haiyan formed as a tropical depression in the open western Pacific on November 3, 2013.

Origins and naming
The origin of Typhoon Haiyan can be traced back to an area of disturbed weather centered roughly 420 km (260 mi) east-southeast of Pohnpei that began to persist early on November 2. At the time the system exhibited a broad, low-level circulation center and scattered, albeit somewhat centralized shower activity. At 0000 UTC the following day, the Japan Meteorological Agency (JMA) began to monitor the disturbance as a tropical depression tracking slowly westward. Rainbands rapidly consolidated about the center of the storm through the early hours of November 3, and after issuing a Tropical Cyclone Formation Alert at 0530 UTC that day, the Joint Typhoon Warning Center (JTWC) also declared the system as a tropical depression at 0900 UTC. At the time the depression was slightly elongated with convection displaced to the west of the storm's center. Throughout the rest of the day the tropical depression became increasingly organized with more centralized convection and deeper convection. Tracking west-northwestward around the southern periphery of a subtropical ridge, the depression was upgraded by the JMA to tropical storm intensity at 0000 UTC on November 4; consequently the tropical cyclone received the name Haiyan. The JTWC followed suit three hours later by classifying the system as a tropical storm.

Upon being named early on November 4, Haiyan had maximum sustained winds of 65 km/h (40 mph) and a minimum barometric pressure of 1002 mbar (hPa; 29.59 inHg). Despite maintaining a broad and disorganized center of circulation, Haiyan's central convection and spiral rainbands continued to organize and consolidate throughout the day, a trend that persisted since tropical cyclogenesis. A gradual strengthening trend over the course of the day ultimately led to the JMA upgrading the system to severe tropical storm status at 0000 UTC on November 5 with winds of 95 km/h (60 mph) and a central pressure of 990 mbar (hPa; 29.24 inHg). At roughly the same time, Haiyan began developing an eye-feature with tightly-curved banding features evident on microwave imagery. In addition, the system had a favorable outflow pattern enhanced by a tropical upper tropospheric trough to the northeast. This enabled the JTWC to reclassify Haiyan as a typhoon at 0300 UTC on November 5. Shortly after reclassification Haiyan began to develop an organized central dense overcast. By 1500 UTC that same day, the JTWC determined the typhoon to have reached the equivalence of a Category 2 hurricane on the Saffir–Simpson scale and indicated that Haiyan had entered a phase of rapid intensification. Subsequently the JMA upgraded the severe tropical storm to typhoon intensity with winds of 130 km/h (80 mph) and a minimum pressure of 970 mbar (hPa; 28.65 inHg) at 2100 UTC. This made Haiyan the thirteenth tropical cyclone of at least typhoon intensity according to the JMA in the western Pacific for 2013.

Peak intensity and first landfall
Haiyan continued to rapidly intensify after being classified as a typhoon on November 5. Late that day, the storm developed a pinhole eye measuring only 11 km (7 mi) in diameter. As a result, the JTWC estimated Haiyan to have one-minute sustained winds of 195 km/h (120 mph), making the storm equivalent in strength to a major hurricane and denoting an increase of one-minute sustained winds by 95 km/h (60 mph) in just 24 hours. Meanwhile, the JMA estimated the storm's winds to be at a much lower intensity at 140 km/h (85 mph), but analyzed Haiyan's central pressure at 965 mbar (hPa; 28.50 inHg), similar to the JTWC's estimates. Continuing to maintain its small eye and strong convective core, intensification continued as the JTWC upgraded Haiyan to super typhoon intensity at 0300 UTC on November 6 as the storm was located roughly 285 km (180 mi) southeast of Yap.

Throughout November 6 the typhoon continued to become more symmetrical and convection progressively deepened. At 1500 UTC that day, Haiyan entered the area of responsibility of the Philippine Atmospheric, Geophysical and Astronomical Services Administration (PAGASA). As a result the agency designated the typhoon with the name Yolanda. By this time the JMA analyzed the typhoon to have deepened to a minimal pressure of 920 mbar (hPa; 27.17 inHg) and intensified to sustained winds of 205 km/h (125 mph). At the same time the JTWC indicated that the system had reached the threshold of Category 5-equivalent intensity. Later that day, the storm made its closest approach to Palau as it passed roughly 100 km (65 mi) to the north. By the day's end, Haiyan maintained sustained winds of 215 km/h (135 mph) and a barometric pressure of 905 mbar (hPa; 26.73 inHg) with little signs of weakening. At the time, this tied Typhoon Lekima as the strongest tropical cyclone in the western Pacific and worldwide in 2013.

Haiyan remained a Category 5-equivalent typhoon into November 7 with a strong convective eyewall and favorable radial outflow. In the early hours of the day, the typhoon began to develop deep, concentric rings around the eye. At 1200 UTC, the storm's central barometric pressure officially deepened below 900 mbar (hPa; 28.58 inHg) to reach 895 mbar (hPa; 26.43 inHg). Sustained winds at the time were estimated at 230 km/h (145 mph). According to the JMA, this would be Haiyan's peak intensity. Based on winds, this made it the second strongest typhoon in recorded history, only behind Tip in 1979; based on barometric pressure Haiyan was the strongest since Megi in 2010. However, according to the JTWC, the system continued to intensify, and at 2100 UTC on November 9, the agency estimated the storm's one-minute sustained winds to have reached 315 km/h (195 mph) as satellite intensity estimates using the Dvorak technique continued to analyze Haiyan to have maxed out the scale with T#8.0. At the same time the typhoon developed a nearly annular eyewall. Shortly after, still at peak intensity, Haiyan made its first landfall over Guiuan, Eastern Samar.

Philippines and South China Sea


Following Haiyan's first landfall on the Philippines at 1940 UTC (0440 PST) on November 7, the typhoon would make a total of five landfalls on islands in the Central Philippines. At 2300 UTC (0700 PST), Haiyan made its second landfall near Tolosa, Leyte near peak intensity. This was followed by landfalls on Daanbantayan, Cebu and Bantayan, Cebu at 0140 UTC (0940 PST) and 0240 UTC (1040 PST), respectively. Land interaction with the central Philippine islands caused Haiyan to shrink in size; the storm's overall convective structure also waned. As a result, the JTWC decreased the typhoon's estimated one-minute sustained winds to 295 km/h (185 mph). An hour later, the typhoon made its fifth landfall at that intensity on Concepcion, Iloilo.

Records

 * Second strongest (wind) according to JMA in the Western Pacific, behind Tip
 * Strongest (wind) according to JTWC since 1961
 * Strongest tropical cyclone worldwide
 * Strongest landfalling tropical cyclone worldwide
 * Strongest 2013 tropical cyclone worldwide
 * One of the strongest WPAC typhoons on record