North Pacific Tropical Cyclone Season Finally Gets Underway

2015 saw very high levels of tropical cyclone activity across the North Pacific due to the strong El Niño. Numerous records were broken during the season which included the exceptionally strong Hurricane Patricia in the eastern North Pacific. In recent months the El Niño has rapidly waned with slightly cooler than average sea surface temperatures now being present in the equatorial eastern Pacific.

In contrast to last year, 2016 has seen an exceptionally quiet start to the North Pacific season. In the western North Pacific Nepartak, the first tropical storm of the season, formed on 3 July. The last time there was such a quiet start to a season was in 1998 when the first storm formed on 8 July. However, the stormless period in the western North Pacific leading up to the formation of Nepartak was slightly longer than that in 1997-8. Like this year, 1998 was also the year after a strong El Niño and historical data suggests that tropical storm formation can be suppressed in the western North Pacific as an El Niño event wanes.

In the central North Pacific, Hurricane Pali developed in January, but there have been no storms since then. In the eastern North Pacific, Tropical Storm Agatha formed on 2 July. The last time the season started later than this was in 1969 when the first storm formed on 3 July.

Whilst Tropical Storm Agatha was fairly short-lived, it was soon joined by a second storm in the eastern North Pacific which is now Hurricane Blas. As with many eastern North Pacific tropical cyclones it is likely to remain out at sea. However, the same cannot be said for Typhoon Nepartak in the western North Pacific which looks set to head towards Taiwan and make landfall later this week as indicated by the Met Office strike probability forecast map.

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Met Office tropical cyclone forecast strike probability from 0000 UTC on 5 July 2016. This shows the probability of a tropical storm passing within 120 km in the next seven days.

Heavy rain across Taiwan and nearby parts of China is likely with 200-300 mm rain in 24 hours possible. Increased rainfall may also be triggered over areas not directly in the path of the typhoon such as the Philippines and South Korea.

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Recent satellite image of Typhoon Nepartak (credit: NOAA/RAMMB)

Official warnings for the latest tropical cyclones in the western North Pacific are produced by the Japan Meteorological Agency. Central North Pacific warnings are issued by the Central Pacific Hurricane Center and eastern North Pacific 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. You can keep up to date on current tropical storms via @metofficestorms on Twitter and through our Storm Tracker page.

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