Jeff co-founded the Weather Underground in 1995 while working on his Ph.D. He flew with the NOAA Hurricane Hunters from 1986-1990.
By: Dr. Jeff Masters , 2:59 PM GMT on August 09, 2014
Tropical Storm Iselle has dissipated after making landfall along the southeast shore of Hawaii's Big Island near 9 am EDT (3 am HST) Friday 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. Iselle brought torrential rains of up to 4" per hour to the Big Island; two locations received over 14" of rain. Iselle did considerable damage on the Big Island, downing trees, knocking down power lines, and damaging a few homes in Hawaiian Paradise Park in Puna. About 22,000 customers lost power during the height of the storm on the Big Island; power had been restored to all but 9,000 by Saturday morning. About 1900 customers lost power on Oahu, and 8,000 on Maui.
Figure 1. Damage to power lines on the Big Island on August 8, 2014, from Tropical Storm Iselle. Image credit: Hawaiian Electric Companies.
Some peak wind gusts and rainfall amounts from Iselle:
72 mph gust at Oahu Forest mesonet site on Oahu (2300')
68 mph gust at Kaneola, HI (815')
91 mph gust at Mauna Kea on the Big Island (13,700')
62 mph gust at Lanai
61 mph gust at Kula, Maui
57 mph gust at Molokai
54 mph gust at Hilo Airport
14.51", Kulani NWR
14.28", Saddle Quarry
12.19", Pua Akala
3.61", Hilo Airport
Wunderground's weather historian, Christopher C. Burt, has an interesting post showing how Iselle's rainfall on the Big Island fell in climatologically favored regions that receive heavy rains at other times of year.
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.
Figure 3. Score: Mauna Loa 1, Iselle 0. The twin 13,000' peaks of the Big Island, Mauna Loa and Mauna Kea, seriously disrupted Tropical Storm Iselle as its center crossed the southern portion of the Big Island, as seen in this true-color MODIS image from approximately 21:15 UTC (5:15 pm EDT) August 8, 2014. At the time, Iselle had top winds of 50 mph. Image credit: NASA.
Hurricane Julio expected to skirt Hawaii
Hurricane Julio continues to steadily weaken, and was a Category 2 storm with 100 mph winds at 11 am EDT Saturday morning. Satellite loops show that the cloud tops of Julio's heavy thunderstorms have warmed and the eye is no longer distinct. 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 Saturday morning runs of our top track models all predicted that the center of Julio would pass 100 - 400 miles northeast of the Hawaiian Islands on Sunday and Monday. 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.
Figure 4. Super Typhoon Genevieve as seen by the VIIRS instrument on the Suomi satellite on 01:30 UTC August 8, 2014. In the infrared image (top), note how the temperature in the eye was as warm as 25°C, while the coldest cloud tops of the eyewall thunderstorms were -80°C, indicating that they had risen very high into the atmosphere where the air is cold. At the time, Genevieve was a Category 5 storm with 160 mph winds. Image credit: Dan Lindsey, NOAA/CIRA.
Typhoon Genevieve not a threat to land
What was formerly Hurricane Genevieve is now 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. Genevieve put on a spectacular 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, but weakened to a Category 3 storm with 120 mph winds as of Saturday at 8 am EDT. Satellite images show that Genevieve is still an impressive storm with a large eye surrounded by intense eyewall thunderstorms with cold cloud tops. Fortunately, Genevieve is not expected to threaten any land areas.
Figure 5. Radar image of Tropical Storm Halong nearing the coast of Japan at 9:55 am EDT (22:55 JST) August 9, 2014. Halong had 70 mph winds at the time. Image credit: Japan Met Agency.
Rare emergency warning for Tropical Storm Halong in Japan
In the Western Pacific, slow-moving Tropical Storm Halong weakened to a 70 mph tropical storm Saturday, but is dumping dangerous heavy rains into Southern Japan. A rare "emergency weather warning" (tokubetsu keihō) for the Mie Prefecture was issued on Saturday by the Japan Meteorological Agency (JMA). Hakusan in the Mie Prefecture had nearly 17 inches of rain on Saturday, breaking its all-time 24-hour rainfall record set just last year in Typhoon Man-yi. The Sukumo observation site in Kōchi prefecture set an all-time calendar-day record rainfall today of 327.5 mm (12.89 inches) with records dating back to 1943. Rainfall rates have been 1 to 2 inches pre hour across most of Kōchi Prefecture on Saturday. As of 9 pm JST Saturday, the center of Halong was 60 km (35 mi) south of Cape Ashizuri, Kōchi Prefecture; the Shimizu observation site, 5 miles northwest of that cape, clocked an 83-mph gust at 9:23pm JST (8:23am US EDT). That's the highest gust anywhere in Japan (including the smaller southern islands) so far Saturday their time. Farther east, Cape Muroto clocked a sustained wind of 27.0 m/s (60 mph) at 9:58pm JST (8:58am US EDT), the top sustained wind for all of Japan today. Source: JMA (thanks to TWC's Nick Wiltgen for these stats.) Satellite loops show that Halong is a very large system, and the rains from this massive, slow-moving storm are going to cause serious flooding problems in Japan.
The Atlantic is quiet
In the Atlantic, there are no threat areas to discuss, and none of the reliable models for predicting tropical cyclone genesis predicts development over the next five days. The African Monsoon will crank out strong tropical waves that will emerge from the coast of Africa on Wednesday and next Saturday. The peak part of the Atlantic hurricane season usually begins in mid-August, so we will need to start paying extra attention to these tropical waves.
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