26 May 2014

Record-strength May hurricane in eastern Pacific

Hurricane Amanda has not only become the first named storm of the eastern Pacific hurricane season, but also the strongest May storm on record for the region.

Amanda was born over the open waters of the eastern Pacific Ocean last Thursday, having near-perfect conditions in which to form.

One of the main drivers of her development has been the anomalously warm sea surface temperatures in the area – something that acts as an energy source for storms to grow stronger. 


Within three days, Amanda gained category-one hurricane status, before rapidly increasing to category-four in just 24 hours during Saturday into Sunday.

According to the National Hurricane Center (NHC) in Miami, Hurricane Amanda at her peak strength on Sunday, has sustained winds of 155mph – placing the storm at the top end of category-four.

Posing no threat to land, she has been described as a fish storm, only bothering marine life out at sea.

However, Amanda’s demise will be as quick as her development, with the storm weakening to a tropical depression by Thursday, local time.

The reason for her rapid weakening is due to moving into an area with colder sea surface temperatures, dry air and strong wind shear (wind blowing in different directions at different heights – tearing the storm apart).

What is needed for a hurricane to form?

– A source of warm, moist air with the temperature at the surface of the oceans at 27C or more

– Winds at the surface converging together and forcing air upwards, allowing thunderstorms to form

– Enough distance from the equator to provide some spin to get the storm to circulate.

– Winds that don’t change too much with increasing height in the atmosphere. This allows the storm to form without getting torn apart.

El Nino’s influence this year

Whilst the eastern Pacific hurricane season is underway, the Atlantic hurricane season doesn’t start until 1 June.

NOAA has predicted that this year’s Atlantic hurricane season will produce fewer storms than average, due an El Nino event that’s expected to develop in the coming months.

warm_sst_wpEl Nino is a naturally occurring ocean-atmosphere phenomenon that is characterised by unusually warm surface water temperatures in the central and eastern Pacific.

It is important because it has a significant impact on the climate in may parts of the world, with a warming influence on global temperatures.

For the next six months, all eyes will no doubt be scanning satellite imagery to watch out for potential storms – especially if they make landfall, potentially having huge impacts.

I’ll be tweeting about storms as they develop through the season, so stay up to date by following me on Twitter – @liamdutton

Satellite image: Nasa

Tweets by @liamdutton