Tropical Depression Auring (2009) - Meteorological History

Meteorological History

Late on January 1, 2009, the Joint Typhoon Warning Center (JTWC) reported that an area of deep atmospheric convection had persisted for the last 48 hours about 730 km (455 mi), to the southeast of Manila in the Philippines. Deep convection was developing over the northern quadrant of a weak low level circulation center. A subtropical ridge of pressure was helping to guide the disturbance and was providing good outflow as well as low to moderate vertical wind shear. However as the disturbance was moving into a higher level of vertical wind shear the depression was not expected to develop into a significant tropical cyclone within 48 hours. During the next 48 hours the disturbance gradually developed, with the Japan Meteorological Agency (JMA) and the Philippine Atmospheric, Geophysical and Astronomical Services Administration (PAGASA) reporting early on January 3 that it had become the first tropical depression of the season, with the name Auring being assigned to the depression by PAGASA whilst it was located about 140 km (85 mi) east of Surigao City on the Philippine island of Mindanao. This came after the low level circulation center had started to consolidate as deep convection was being fueled by a poleward diffluence despite being in an area of strong vertical wind shear. Over the next couple of days as Auring moved towards the east, dry air started to wrap in to its low level circulation center which started to weaken the depression after it had peaked with winds of 45 km/h, (30 mph) and a peak pressure of 1006 hPa/Mbar. As the baroclinic zone approached the depression late on January 5, PAGASA downgraded the depression to an area of low pressure as the baroclinic zone was approaching the depression, as vertical wind shear had increased and outflow became hindered. However the JMA continued to issue warnings on the depression until early the next morning when the depression was declared dissipated by the JTWC and the JMA.