Wednesday, August 6, 2014

Hawaii Braces for Tropical Punch

The Atlantic may be quiet as far as tropical activity is concerned, but that is not the case in the Pacific. There are currently three systems in the central Pacific, and two of them are posing a threat to the Hawaiian Islands.

Genevieve, the furthest west storm and the strongest of the three with sustained winds of 135 mph, is located about 1680 miles west southwest of Hawaii. All eyes, however are on Hurricane Iselle and Hurricane Julio.  As of 5:00 p.m. HST  (11:00 p.m. EDT) Hurricane Iselle was was 510 miles east-southeast of Hilo. The maximum sustained winds in Iselle were 90 mph, and it's forward speed was to the west-northwest at 18 mph. At this rate Hurricane Iselle will reach the Big Island on Thursday. Iselle is expected to maintain strength.  A hurricane warning is in effect for the Big Island and surrounding waters, and a tropical storm warning is in effect for all the remaining islands except Niihau and Kauai, where tropical storm watch is in effect. Although the exact storm track is far from certain, heavy rain, heavy surf, and damaging winds are expected to spread across the island tomorrow and Friday.

5-day forecast track for Iselle as of 5:00 p.m. HST (11:00 p.m. EDT) today.
If you look at the satellite image of the storms above and the location of the Hawaiian Islands, it's not hard to realize that hurricanes are relatively rare in Hawaii. It's a small target in a very big ocean. The average climatological hurricane track in the central Pacific is located to the south of Hawaii. In addition tropical systems that approach Hawaii from the east tend to weaken because of unfavorable wind shear and cooler sea surface temperatures. The last time a hurricane made landfall in Hawaii was in 1992 when Hurricane Iniki made landfall in Kauai in early September. This category 4 storm took 6 lives and caused $1.8 billion in damage.

Satellite image of Hurricane Iniki on September 11, 1992.

So, right now we have one hurricane bearing down on the islands, and a second one following close behind. It's unusual enough to have two tropical systems to hit Hawaii in one season, much less in the span of three days.

At 5:00 p.m.. HST (11:00 p.m. EDT) Hurricane Julio was located 1555 miles east of Hilo, moving to the west northwest at 16 miles per hour. Residents of Hawaii will get about 24 hours or so to get ready for Julio after Iselle passes through. The present forecast brings the center of Julio just to the north of the islands late Saturday and Sunday.

5-day forecast track for Hurricane Julio issued at 11:00 p.m. EDT.
Of course, the exact track of both storms is still uncertain at this time, but it appears that Hawaii is in store for a one-two tropical punch over the next four days.

Information on Hurricane Iselle can be found on the NWS Central Pacific Hurricane Center web site. Information on Hurricane Julio is available on the National Hurricane Center web site   Once Julio moves west of 140°W longitude, the Central Pacific Hurricane Center will take over monitoring and forecasting responsibilities for this storm.

The latest watches, warnings, and advisories for the Hawaii can be found on the NWS Honolulu web site. The information I've included about the storms is valid as of late on August 6, so be sure to check these web sites if you are interested in the latest updates.

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