Taiwan is preparing for the arrival of Nepartak, a massive typhoon that is expected to cause heavy rains and flooding.

Typhoons are common in Taiwan - category 5 typhoons, though, are not that usual. Since 1950 there have been 18 cyclones of this most violent category, and Super Typhoon Nepartak would be number 19.

It is the first named storm of 2016 and is currently a category 5, as defined by the Saffir-Simpson international scale.

Even though the major El Nino of last year has now collapsed, the northwest Pacific typhoon season is having its second slowest start in nearly 70 years. That will be of no comfort to the inhabitants of Taiwan who can expect the onset of typhoon weather later on Thursday.

Taitung and Hualien counties in eastern Taiwan are likely to be the first to be hit by Nepartak. They contain a long, low river valley so flooding is likely. The forecast rainfall is expected to be at least 300mm.

Current measurements by NASA suggest cloud tops of 17,000 metres, or 56,000 feet, which mean that thunderheads around the typhoon's eye are punching through the top of the atmosphere. Rainfall rates over the ocean could be as high as 190mm per hour.

As Nepartak's eye makes landfall, it will lift the Pacific's surface by between one and two metres in what is known as a "storm surge". This is often the most devastating element of a typhoon, being similar to a small tsunami.

In the case of Super Typhoon Nepartak, the wind could also be destructive. Steady winds of 230 kilometres an hour will be boosted by gusts as high as 280km/h.

Curiously, this is the second typhoon called Nepartak, the first being a mere category 1 storm that hit the Philippines in November 2003.

Appropriately, the epithet Nepartak is derived from the name of a conquering warrior from the island of Kosrae in Micronesia.

Nepartak is likely to lose a lot of energy over Taiwan, but it is forecast to regain some strength over the Taiwan Strait.

The Chinese mainland is then under threat, mostly from torrential rainfall, as Nepartak makes landfall on the vulnerable coast of Fujian Province.