Typhoon Dujuan has today (Monday 28 September) made landfall over Taiwan on the western rim of the Pacific Ocean with sustained winds well in excess of 100 mph. Dujuan is expected to drop large amounts of rainfall – 500mm is possible – over the mountainous interior of the island which could result in serious flooding and landslides. Within the first few hours of the typhoon affecting Taiwan 142mm of rainfall has already been recorded in Taipei.

Dujuan comes just seven weeks after Typhoon Soudelor struck the same part of northern Taiwan with a similar intensity. Soudelor caused flooding, destruction due to strong winds and some loss of life. Dujuan is expected to take a similar track to Soudelor – crossing the Taiwan Strait and reaching the Pacific coast of mainland China tomorrow (Tuesday 29 September) before moving inland.

Typhoon Dujuan just prior to landfall on 28 September 2015
Image courtesy of JMA.

Typhoon Dujuan after making landfall on 28 September 2015
Image courtesy of MTSAT.

Dujuan and Soudelor are two of many strong typhoons and hurricanes which have occurred across the Pacific Ocean this year. One of the main contributing factors to the high level of storm activity is the strong El Niño which has developed. This is characterised by a marked warming of the tropical east Pacific Ocean. A strong El Niño can alter weather patterns in many parts of the world and in particular results in increased Pacific tropical cyclone activity. The last time an El Niño of the current strength occurred was in 1997-8 when high levels of Pacific tropical cyclone activity were also experienced.

In total there have been 43 tropical cyclones across the whole of the Pacific Ocean this year. 19 of these have acquired ‘major’ status – category 3 or above on the Saffir-Simpson Hurricane Wind Scale. The northern hemisphere season usually continues through October and November and in some seasons extends into December as well.

In addition to Typhoon Dujuan there are also two other tropical storms in the Pacific at present. Tropical Storm Niala is located in the central Pacific just south of Hawaii. It is not expected to impact Hawaii directly as it gradually weakens. The central part of the North Pacific Ocean surrounding Hawaii has seen a record number of tropical storms form this season, although Hawaii itself has avoided a direct strike from any of the storms so far.

Over in the far eastern Pacific Ocean Tropical Storm Marty is just under hurricane strength and is moving slowly towards the coast of Mexico. It is not certain yet whether Marty will make landfall, but a tropical storm watch has been issued for coastal areas including the resort of Acapulco.

Official warnings for the latest tropical cyclones in the western North Pacific are produced by the Japan Meteorological Agency. Central Pacific warnings are issued by the Central Pacific Hurricane Center and east Pacific and Atlantic warnings by the US National Hurricane Center. The Met Office routinely supplies predictions of cyclone tracks from its global forecast model to regional meteorological centres worldwide, which are used along with guidance from other models in the production of forecasts and guidance. We also provide updates on current tropical storms via @metofficestorms on Twitter.