Hawaii Soon To Be Hit By Two Hurricanes

Hurricanes Iselle and Julio will be hitting Hawaii in the next few days. We’ll look at Hawaii itself, satellite imagery of the hurricanes, current warnings and focus in on one effect of hurricanes – storm surges.

Calm waters set to get rougher over the course of the next few days as hurricanes Iselle and Julio impact the Hawaiian islands. [Wikimedia | Simon_sees on the English Wikipedia | CC-BY-3.0]


Hawaii is a chain of islands in the Pacific Ocean, and is part of the USA. It’s made up of six major islands – Hawai’i, Maui, O’ahu, Kaua’i, Moloka’i, Lana’i and Ni’ihau. It has a population of around 1.5 million, but also welcomes millions of tourists each year. The islands are low-lying and mostly uninhabited. It’s seen lots of tropical storms but very few powerful hurricanes.

The volcanic island chain from space. [Wikimedia | Jacques Descloitres at the English Wikipedia | Public Domain].

Iselle is the name given to the first of the two hurricanes, and is a Category 1 (the lowest on the Saffir-Simpson Scale) with 85mph winds.

Julio is the second and currently stronger hurricane, with a category of 2 and winds of over 96mph. It is expected to reduce in power over the next few days, however, and reach Hawaii three days later

Hawaii’s Population Centres

Most of the larger settlements in Hawaii are in these low-lying coastal areas, such as Honolulu – the capital. However large parts of the island chain are uninhabited, so the risk to human lives is limited. The population density map below shows how Hawaii’s population is concentrated in Honolulu, with a few other smaller settlements

Most of Hawaii’s population live in Honolulu, the largest red/orange area. It is on O’ahu, the third largest island in the Hawaiian chain. Most of Hawai’i (a bit confusing), the largest and most southerly island, is completely uninhabited. [Wikimedia | JimIrwin at the English Wikipedia | CC-BY-SA-3.0]

Hurricane Storm Surges

Iselle is expected to create 28-foot waves as it passes over the islands in a storm surge. Storm surges are coastal floods caused by a low-pressure system, which allows the sea to rise a little. Hurricanes are low-pressure systems, so storm surges typically accompany them. Combine them with waves caused by the wind from the hurricane and a high tide, the storm surge can travel far inland. Surges helped flood New Orleans in 2005, when Hurricane Katrina caused massive storm surges along the low-lying coastline. The low-lying areas in Hawaii are likely to be inundated by the initial storm surge from Iselle.

Images of Iselle from Above

The National Environmental Satellite, Data, and Information Service (NESDIS) issues regular satellite imagery, and one of the covered regions is Hawaii. The two images below, taken at the same time, show Hurricane Iselle on it’s approach to the islands

A visible satellite image showing Iselle. The “eye” is visible at the centre of the cell. (Time: 11:30am UTC, Date: 07/08/2014) [NOAA]

Water Vapour map for Hurricane Iselle, traveling towards Hawaii. This shows how much water the centre of the hurricane carries, most of which will be dumped on Hawaii very soon. (Time: 11:30am UTC, Date: 07/08/2014) [NOAA]

Progress of Iselle and Julio

NOAA (the National Oceanic and Atmospheric Administration) compiles archive satellite data into a useful tool which can be used to make weather maps. This image is a cloud-map from 2 days ago, showing both Iselle and Julio.

[Map made with NOAA’s View Data Imagery Portal]

Here is a collection of images from the archive showing how the hurricanes have formed and moved across the Pacific since the beginning of August.

This slideshow requires JavaScript.

[Source: NOAA, NESDIS and SSD. The latest NESDIS/SSD satellite imagery can be found here. NOAA’s Vew Imagery Data Tool was used for the gallery of images]


NOAA had issued this warning map (below) for Hawaii earlier today. The medium pink which makes up the most of the surrounding Pacific Ocean and the southern-most island indicates where there is a hurricane warning out for that region. The dark pink around the central three islands indicates there is a tropical storm warning, which is slightly less powerful than a hurricane. The light pink around the northern-most island indicates the region is under “tropical storm watch”, which means that the people in the area should remain wary of the weather conditions. The green colour which covers the northern-most island indicates there may be flash floods.

The medium pink areas are tropical storm warnings, the dark pink areas are tropical storm warnings and the light pink is "tropical storm watch", which means the area is on high alert for tropical storm conditions. The green area is at risk of flash floods.

Later, it released this map. The forecast has worsened for the northern-most island.


And finally,

The Effects On Hawaii and Preparations

Hawaii will likely be hit hard by the two hurricanes, but it should bounce back fairly quickly from the damage, since it is part of the USA. The biggest issue is going to be the vibrant tourism industry, which will be temporarily shut down by the storms and will result in a fall in profits for the islands. Structural damage is likely to be limited due to the relatively small power of the hurricanes themselves. However, recovering from the disaster may take some time, given the islands’ remote location in the middle of the Pacific Ocean. As previously said, Hawaii will suffer from the storm surges from both hurricanes, because of it’s low-lying coastal regions.

Evacuations have already begun, with tourists being granted free transfers onto planes out of Honolulu. Locals may have to stick it out or buy tickets themselves. With appropriate reactions and help from local and federal government, the cost of the disaster will be limited, and the recover time reduced. It will be especially hard to do so however, given the short time between Iselle’s and Julio’s landfalls.


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These sites will be updated regularly with the relevant information. I’ve referenced all of them throughout the article.


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