In Hawaii hurricanes hardly ever happen

  • Visible satellite image of Tropical Storm Ana taken at 2330GMT Wednesday 15th October 2014. Image courtesy: NASA Goddard MODIS Rapid Response Team

    The forecast track and mean sea level pressure (in hPa) of Ana as it passes Hawaii (Times are in GMT).

    How Ana is showing up on the MeteoEarth app for iPhone.

  • In Hawaii hurricanes hardly ever happen
    16.10.2014 14:26

    This week in MeteoGroup's London office we have been keeping a keen eye on the development of a hurricane in the central Pacific Ocean.  Ana, as the storm system has been named, is currently a tropical storm but looks like intensifying over the next 24-36 hours to reach hurricane status. All the while, Ana is heading towards the islands of Hawaii. This is of interest to us particularly as one of our forecasters is heading to Hawaii on holiday this weekend – coincidence or very good forward planning?

    So what, potentially, does Ana have in store for our colleague and the islands of Hawaii? Like I said, the storm is currently a tropical storm, with maximum sustained winds of 50 knots (57mph) and gusts of 65 knots (75mph). During the next 24-36 hours Ana is expected to deepen, with maximum sustained winds of 65 knots (75mph) and gusts of 80 knots (92mph), by 1800GMT (0800 local time – HAST) Friday 17th October, meaning that Ana will be recatagorised as a hurricane.  Ana is then expected to track north-eastwards just to the south of Big Island (Hawai’i), Maui, Moloka’i and O’ahu, before making landfall on Ni’ihau on Monday 20th October, as it passes between Kaua’i and Nihoa, continuing to track further north-eastwards. The intensity of Ana looks like it will weaken a little as it moves across the waters immediately surrounding the islands, with the chance that it will weaken sufficiently to be downgraded to a tropical storm again before making landfall. Maximum sustained winds are currently forecast to be around 50 knots (57mph), with gusts of 65 knots (75mph) again come 1200GMT (0200 HAST) Monday. However, indications are that Ana will then intesify back up to hurricane status as it continues to move north-eastwards away from Hawaii. 

    Of course, along with strong winds, the storm system will bring with it heavy rain and large sea swell. Waves of up to 6.5m (21 ft) are forecast to affect particularly the south and south-western shores of the islands as the eye of the storm passes by, as well as in it’s immediate wake. Rainfall amounts of up to 300-400mm (11-16 inches) in a 24 hour period are expected for the islands between Saturday and Tuesday, with it looking like O’ahu and Kaua’i will receive the higher end of this range on Monday and Tuesday. 

    To put Ana in a little bit of historical context, Hurricane Iniki was the last hurricane to make landfall, back on 11th September 1992. Iniki was a category 4 hurricane when it hit Kaua’i with 122 knot (140mph) winds, causing almost $2 billion in damage and the deaths of 6 people. Since then, there have been a number of hurricanes and tropical storms that have affected Hawaii, leading to severe weather for the islands, with a few making landfall as tropical storms. The last of these was Iselle in August this year, which hit the Big Island as a strong tropical storm, causing $53 million in damage and killing one person in flooding on Kaua’i. 

    By: Rachel Vince