page_title: Typhoon Songda (2016)
section_title: Meteorological history
hierarchical_section_title: Typhoon Songda (2016) / Meteorological history
caption_attribution_description: English: Post-Tropical Cyclone Songda (the Ides of October storm) as a hurricane-force low near Western Washington at 13:30 PDT (20:30 UTC) on October 15, 2016.
context_page_description: Typhoon Songda was the sixth most intense tropical cyclone of the Northwest Pacific Ocean in 2016. Also known as the Ides of October storm, it struck the Pacific Northwest region of the United States and Canada as a powerful extratropical cyclone. Songda was the twentieth named storm and the ninth typhoon of the annual typhoon season. The system developed into a tropical storm south of Minamitorishima on October 8 and strengthened into a typhoon on October 10. Songda reached its peak intensity southeast of Japan late on October 11 at an unusually high latitude, before it became extratropical on October 13.
context_section_description: On October 2, the United States Central Pacific Hurricane Center started to monitor a weak trough of low pressure that had developed about 1,000 mi (1,610 km) to the southwest of Honolulu, Hawaii. Over the next day as the system moved towards the northwest, showers and thunderstorms gradually developed along the trough, but were showing little to no signs of organisation. The system was subsequently classified as a tropical depression by the Japan Meteorological Agency during October 3, as it crossed the International Dateline and moved into the western Pacific Ocean.
  Often presenting an exposed low-level circulation center (LLCC), the tropical depression drifted westward without further development for days owing to a marginal environment within the subsident region of a tropical upper tropospheric trough (TUTT) cell to the northwest, with moderate vertical wind shear. Late on October 7, the Joint Typhoon Warning Center (JTWC) eventually issued a Tropical Cyclone Formation Alert for the system, when the TUTT cell was beginning to move to the west-southwest, allowing convection to develop over the consolidating LLCC.
  Shortly after the JTWC upgraded the system to a tropical depression early on October 8, the JMA upgraded it to a tropical storm and named it Songda (Vietnamese: sông Đà, meaning “Dark Brown River”) at noon, about 500 km (310 mi) south of Minamitorishima. It was also upgraded to a tropical storm by the JTWC several hours later. The JMA upgraded Songda to a severe tropical storm late on October 9, when it was moving along the southwest periphery of the deep-layered subtropical ridge positioned to the northeast. Later, both of the JMA and JTWC reported that Songda had developed into a typhoon at 00:00 UTC on October 10. Turning northward, the typhoon rapidly intensified and formed a well-defined eye embedded in deep central convection, due to near radial outflow being limited on the southern portion, with a very strong poleward tap into the Westerlies, very low vertical wind shear, and sea surface temperature of 28 ºC. However, the eye became cloud-filled and ragged early on the next day, when Songda began to accelerate northeastward along the poleward side of the subtropical ridge.
  Typhoon Songda reintensified in the afternoon on October 11. Moving in-phase with such strong southwesterly vertical wind shear effectively reduced its overall impacts to the system, allowing a rapid intensification again. Therefore, Songda developed a larger and sharp eye with a very symmetric core structure. It reached its peak intensity about 1,050 km (650 mi) southeast of Tokyo, Japan at 18:00 UTC, with ten-minute maximum sustained winds at 185 km/h (115 mph) and the central pressure at 925 hPa (27.32 inHg) reported by the JMA, at an unusually high latitude (30.3ºN) for such powerful intensity. With one-minute maximum sustained winds at 240 km/h (150 mph) reported by the JTWC, equivalent to a Category 4 of the SSHWS, Songda was also an unusually northern super typhoon. Early on October 12, embedded deeper in the westerlies, the overall structure became more asymmetric with severe elongation and dispersion along the northern peripheries, leading the weakening trend and prompting the JTWC issuing the final warning to Songda, although the eye remained well-defined until the afternoon.
  Moving eastward at 95 km/h (60 mph), shortly after the JMA downgraded Songda to a severe tropical storm early on October 13, the system completed an extratropical transition south of the Aleutian Islands. After the system weakened into a gale-force low and crossed the 180th meridian again in the afternoon, the National Weather Service (NWS) office in Portland dubbed it the Ides of October storm on the next day. On October 15, the system turned northeastward and underwent an explosive intensification. The Ocean Prediction Center (OPC) reported that Post-Tropical Cyclone Songda developed into a hurricane-force low approximately 165 mi (266 km) west of Astoria, Oregon at 11:00 PDT (18:00 UTC), 6 hours before with the central pressure decreasing to 969 mb
caption: Songda as a hurricane-force low near Western Washington on October 15
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