Courtesy: Dr. Jeff Masters, Weather Underground
Tropical Storm Iselle made landfall along the southeast shore of Hawaii’s Big Island near 9 am EDT (3 am HST) as a tropical storm with 60 mph winds. Iselle is only the second tropical storm on record to hit the Big Island, and was the strongest. The Big Island’s other tropical storm was an unnamed 1958 storm that had sustained winds of 50 mph at landfall. Iselle is just the fourth tropical storm or hurricane to make a direct hit on any Hawaiian Island since accurate records began in 1949. Iselle is bringing torrential rains to the Big Island, where a rain gauge near Pahala indicated rain rates at nearly 4 inches per hour. A Flash Flood Warning is in effect for this area, and all of the Hawaiian Islands are under a Flash Flood Watch today. It is too early to assess what damage Iselle may have done, but the NWS reported roofs flying off and downed trees in Hawaiian Paradise Park, and at least 21,000 customers were without power early Friday morning on the Big Island. Some peak wind gusts and rainfall amounts on the Big Island so far from Iselle, as of 11 am EDT (5 am HST) Friday:
The winds on top of the highest point in Hawaii, the Big Island’s Mauna Kea, elevation 13,796′ (4,205 m), gusted up to 72 mph this morning at the University of Hawaii 88″ telescope.
Five stations on the windward side of the Big Island had received at least 10″ of rain in 24 hours as of 5 am HST Friday, according the NWS Hawaii rainfall summary:
Pua Akala: 10.19″
Saddle Quarry: 11.39″
Kulani NWR: 11.19″
Figure 1. Radar image from the South Hawaii radar at 7:49 am EDT August 8, 2014 of Tropical Storm Iselle near landfall on the Big Island. The radar beam is being intercepted by the high mountains of Hawaii, and cannot “see” to the northwest.
Figure 2. True-color MODIS image of Hurricane Iselle from 23:15 UTC (7:15 pm EDT) August 7, 2014. At the time, the outer spiral bands of the 80 mph Category 1 hurricane were spreading over the Big Island of Hawaii. Image credit: NASA.
Forecast for Iselle
Friday morning satellite images showed that Iselle’s thunderstorms continued to be very vigorous with cold cloud tops, but interaction with the high peaks of Mauna Loa and Mauna Kea had severely disrupted the circulation. The storm will have difficultly re-organizing once its center emerges over the ocean, since wind shear is a very high 25 – 30 knots, and water vapor satellite images are showing a lot of dry air on the west side of the Big Island. The shear and dry air should be enough to destroy Iselle by Saturday afternoon.
Figure 3. True-color MODIS image of Hurricane Julio from 19:30 UTC (3:30 pm EDT) August 7, 2014. At the time, Julio was a Category 2 hurricane with 105 mph winds. Image credit: NASA.
Hurricane Julio expected to skirt Hawaii
Hurricane Julio intensified into a Category 3 hurricane with 115 mph winds overnight, becoming the fifth major hurricane in the Eastern Pacific so far in 2014. This is an inordinately high number of major hurricanes–usually, the Eastern Pacific has only three major hurricanes in an entire season, and just one by August 8. Though Julio had weakened to a Category 2 storm with 105 mph winds on Friday morning, satellite loops show that Julio still has an impressive area of heavy thunderstorms and well-formed eye, though the cloud tops are warming, indicating weakening. The storm should be able to take advantage of light to moderate wind shear and marginally warm sea surface temperatures near 26°C and maintain at least Category 1 status until Sunday morning. Fortunately, it is looking increasingly likely that Julio will not have a major impact on the Hawaiian Islands. The Friday morning runs of our top track models all predicted that the center of Julio would pass 100 – 300 miles northeast of the Hawaiian Islands on Sunday. On this path, Julio’s core of heavy rains and wind would miss the islands, and high surf would be the main impact of the storm. The edge of Julio’s cone of uncertainly for Sunday no longer lies over the islands.
Super Typhoon Genevieve not a threat to land
Farther west in the Pacific, what was formerly Hurricane Genevieve is now Super Typhoon Genevieve, after the storm crossed the International Date Line from east to west early Thursday. There is no difference between a North Pacific hurricane and a typhoon other than its location–if the storm is west of the Date Line, it is called a typhoon, and if it is east of the Date Line, it is called a hurricane. This only applies to storms in the Pacific in the Northern Hemisphere; in the Southern Hemisphere’s Pacific Ocean, everything is called a Tropical Cyclone regardless of which side of the Date Line it falls on. Genevieve put on an amazing display of rapid intensification, going from a tropical storm with 60 mph winds to a Category 5 super typhoon with 160 mph winds in just 27 hours, from 09 UTC August 6 to 12 UTC August 7. Genevieve spent 24 hours as a Category 5 storm, before weakening slightly to a 150 mph Category 4 storm at 8 am EDT Friday. Satellite images still show an very impressive storm with a large eye surrounded by a giant area of intense eyewall thunderstorms with very cold cloud tops. Fortunately, Genevieve is not expected to threaten any land areas.