Typhoon Guchol (2012)

Map plotting the storm's track and intensity, according to the Saffir–Simpson scale

Map key

Saffir–Simpson scale

  Tropical depression (≤38 mph, ≤62 km/h)
  Tropical storm (39–73 mph, 63–118 km/h)
  Category 1 (74–95 mph, 119–153 km/h)
  Category 2 (96–110 mph, 154–177 km/h)
  Category 3 (111–129 mph, 178–208 km/h)
  Category 4 (130–156 mph, 209–251 km/h)
  Category 5 (≥157 mph, ≥252 km/h)
  Unknown

Storm type

Tropical cyclone

Subtropical cyclone

Extratropical cyclone, remnant low, tropical disturbance, or monsoon depression

In early June, a tropical disturbance, embedded within the end of a monsoon trough, formed to the southeast of Guam.[2] The Joint Typhoon Warning Center (JTWC) then started to monitor the system late on June 7, as it had scattered deep convection over its poorly-defined low-level circulation center (LLCC), but was under an environment of 28–30 °C (82–86 °F) sea surface temperatures, low vertical wind shear, good divergence and enhanced poleward outflow.[3] As the system moved westward, it significantly organized, prompting the JTWC to issue a Tropical Cyclone Formation Alert (TCFA) by the next day.[4] However, the JTWC canceled the TCFA late on June 9, as its center became elongated.[5] The system then started to reorganize by the next day,[6] and by June 11, the Japan Meteorological Agency (JMA) upgraded the system into a tropical depression.[7] The JTWC later followed suit, as formative bands wrapped around its center.[8] As it continued westward, the system struggled to organize, with its center becoming ill-defined.[9]

By 03:00 UTC the next day, the JTWC reported that the tropical depression had intensified into a tropical storm, as improved convective banding began wrapping into its center.[10] The JMA upgraded the storm three hours later, naming it as Guchol.[11] Over the next few days, Guchol slowly intensified, as convection continued to wrap into the system.[12] By 00:00 UTC on June 14, the JMA upgraded Guchol to a severe tropical storm.[13] It subsequently entered the Philippine Area of Responsibility, with the PAGASA naming it locally as Butchoy.[14] At 15:00 UTC, the JTWC upgraded the system to a Category 1-equivalent typhoon on the Saffir-Simpson scale, as it built a central dense overcast.[15] By the next day, it further strengthened to a Category 2-equivalent typhoon, as an outflow channel became apparent while it took a north-northwestward turn around the western periphery of the subtropical ridge.[16][2] At 21:00 UTC that same day, the JTWC upgraded Guchol to a Category 3-equivalent typhoon.[17] The JMA upgraded Guchol to a typhoon three hours later, on June 16.[18] Nine hours later, Guchol strengthened into a Category 4-equivalent typhoon, as a 18 nmi (33 km) symmetric eye formed.[19] Guchol ultimately reached its peak intensity at 18:00 UTC that same day, with 10-minute sustained winds of 100 knots (185 km/h; 115 mph) and a central pressure of 930 hectopascals (27 inHg), according to the JMA.[20] The JTWC estimated Guchol to have 1-minute sustained winds of 130 knots (240 km/h; 150 mph), although it noted that the system's eye had become less symmetric.[21]

By the next day, Guchol started its eyewall replacement cycle, as double eyewalls were seen in microwave imageries.[22] The system then started to weaken from its peak intensity at 12:00 UTC that day,[20] as it was completing the replacement cycle while moving into slightly cooler sea surface temperatures.[23][2] At 09:00 UTC on June 18, Guchol weakened into a category 3-equivalent typhoon, as its eyewall deteriorated while turning to the north-northeast, along with increasing wind shear.[24] It then exited the Philippine Area of Responsibility three hours later, with the PAGASA issuing its final advisory on the system.[25] The JTWC further downgraded Guchol to a category 2-equivalent typhoon as its eye became cloud-filled.[26] On June 19, Guchol weakened to a category 1-equivalent typhoon, as its convection began to elongate while interacting with the mid-latitude westerlies,[27] before further weakening to a tropical storm as it rapidly approached the Kii Peninsula.[28] At 08:00 UTC, Guchol made its first landfall over southern Wakayama Prefecture, as it began its extratropical transition.[1][2] Three hours later, it made its second landfall in eastern Aichi Prefecture.[1] Subsequently, the JMA downgraded Guchol to a severe tropical storm,[29] and the JTWC issued their final advisory on Guchol.[30] Traversing the Kanto-Koshin region, the system emerged to the coast of Fukushima Prefecture, with the JMA issuing their final advisory by the next day, as it fully became an extratropical cyclone.[1][31] The remnants of the system was last noted near Hokkaido two days later.[20]

• Typhoon Man-yi (2013)
• Tropical Storm Talas (2011)

Wikimedia Commons has media related to Typhoon Guchol (2012).

• JMA General Information of Typhoon Guchol (1204) from Digital Typhoon
• JMA Best Track Data of Typhoon Guchol (1204) (in Japanese)
• JTWC Best Track Data of Super Typhoon 05W (Guchol)
• 05W.GUCHOL from the U.S. Naval Research Laboratory