The Weather Channel graphic
Hurricane Iselle is about 700 miles south-southeast of Hilo, the most eastward city in Hawaii, and moving toward the islands at about 15 miles an hour. High surf is expected to start slamming the beaches facing east today, with high winds and the storm surge reaching the Big Island and Maui on Thursday. The islands are under a Tropical Storm Watch issued by the Central Pacific Hurricane Center — and there is another big storm, Hurricane Julio, trailing about 900 miles behind Iselle. It's apparently rare for hurricanes to line up on Hawaii just a few days apart.
The track of both storms is currently aimed right at the islands. Iselle might weaken to a tropical storm by the time it arrives, but the thing about hurricanes is they never really know. From this morning's hurricane statement for Hawaii's islands:
Iselle is expected to bring heavy rains, high surf and strong winds. Tropical storm conditions could reach the Big Island on Thursday and Maui county late on Thursday. If Iselle remains on the forecast track, tropical storm conditions could affect the Oahu and Kauai county through Friday. High surf is expected to reach the islands ahead of the heavy rains and strong winds. The high surf may bring coastal flooding, particularly when combined with afternoon astronomical high tides....
With some uncertainty in the exact track and strength of Iselle, it is still too early to determine which islands are at most Risk from Iselle. However, the Big Island and Maui county will be the first areas to experience the impacts of Iselle.
It is vital that you do not focus on the exact forecast track. Forecast movement, direction, and speed are only estimates. Even small errors in the forecast track can mean major differences in where the worst conditions will occur. Damaging effects can extend far from the center.
For those under a watch, now is the time to prepare. Do not wait until it is too late. Stay calm and keep informed. Closely monitor NOAA weather radio or other local news outlets for official storm information. Listen for warnings or changes to the forecast.
Be ready to evacuate if necessary.