Twin Typhoons: Goni Momentarily Stalls, but Has Eye on Taiwan, Japan; Atsani Turning out to Sea

Jon Erdman
Published: August 21,2015

Twin typhoons Goni and Atsani are churning through the tropical western Pacific Ocean. One is beginning to affect the northern Philippines and Taiwan, and will also affect Japan's Ryukyu Islands this weekend. The other may affect another set of Japanese islands, but appears unlikely to make a direct hit on the Japanese mainland.
(MORE: Record Year to Date in the Western Pacific)
According to the U.S. military's Joint Typhoon Warning Center, Typhoon Goni was located about 480 miles southwest of Kadena Air Base, Japan, and had maximum estimated sustained winds of 100 mph as of 11 p.m. U.S. EDT Friday. That makes it the equivalent of a Category 2 hurricane on the Saffir Simpson Hurricane Wind Scale. While Goni's intensity may fluctuate through much of the weekend, a gradual weakening trend is likely early next week.
Meanwhile, Typhoon Atsani is churning hundreds of miles to the northeast. As of 11 p.m. EDT Friday (12 p.m. Saturday Japan time), it was centered about 240 miles northeast of Iwo Jima with maximum sustained winds of 100 mph, as it has been slowly weakening. Atsani had been a Category 5 equivalent super typhoon Wednesday, but is expected to continue slowly losing strength in the days ahead.
(SOUDELOR RECAPS: Impacts | Reports | Images | Rain Visualization)
Below we have the latest forecast details and uncertainties for both Goni and Atsani.

Infrared Satellite: Twin Systems

Typhoon Goni: Land Impacts Occurring

Forecast Path: Goni

As Goni made its closest pass to the Philippine island of Luzon, the forward speed of the system came to nearly a complete stop. This has proved problematic as a steady stream of heavy rain and gusty winds have been lashing the Batanes and Babuyan Islands of the northern Philippines.
After stalling for a time, steered by high pressure aloft just south of mainland Japan, Goni will soon gain speed and impact parts of Taiwan and Japan's Ryukyu Islands, including Okinawa into this weekend.
Goni will head north-northeast in response to a southward dip in the jet stream over eastern China. Goni will likely still remain a dangerous typhoon, though weakening is likely as the storm begins to accelerate to the north-northeast
For now, the peak impacts will be in the northern Philippines (Batanes and Babuyan Islands) through early Saturday, followed by Taiwan and Japan's Ryukyu Islands Saturday through Monday.
(FORECASTS: Taipei | Shanghai)

Typhoon Goni Wind Probabilities

Peak Wind Gust Reports

Rainfall Amounts So Far

The official meteorological agency of the Philippines PAGASA continues a storm signal three for the Batanes Islands and northern Cagayan. This means winds of 75 to 105 mph are possible in the next 24 hours. Moderate to heavy rainfall is also expected and storm surges up to eight feet are possible in the coastal areas of Cagayan. Goni is known by the name Ineng in the Philippines.
Sustained tropical storm-force winds of 45 mph (72 kph) have already been reported on the island of Calayan as well as at the Basco Radar Site on Batan Island. Gusts to 51 mph were recorded at Aparri on the island of Luzon.
Aparri also picked up almost 10 inches of rain in 24 hours ending Friday evening, local time. Farther south, Baguio City picked up 9.65 inches of rain in that same time period from the southern rainbands of Goni.
Once the storm finally turns away from the northern Philippines, it appears that the center of Goni will move east of Taiwan. Even though the current forecast keeps the center of Goni east of Taiwan, the western side of the typhoon is still likely to bring heavy rainfall and strong wind gusts.
The Taiwanese island of Lanyu, southeast of the main island of Taiwan, has already reported wind gusts up to 72 mph (32 meters per second) as of 8 a.m. local time Friday (8 p.m. U.S. EDT Thursday). Red alerts for torrential rain have been posted by Taiwan's Central Weather Bureau for the mountains and eastern slopes of eastern Taiwan.
Goni should then take a path through the southern Ryukyu Islands of Japan, including but not limited to the populated islands of Ishigakijima and Miyakojima. Depending on how sharp the recurvature is, the center of Goni could also pass near the main island of Okinawa, including Kadena Air Base, with a closest approach of the center sometime Monday.
Uncertainty remains with where Goni will head next week beyond that. In recent days, some computer model runs have taken a weakened Goni towards western mainland Japan (especially the island of Kyushu) and then near or into the Korean Peninsula. Others have taken the storm into the Sea of Japan, which is east of the Koreas, and into either northeast China or Russia's Far East. It's too early to know the ultimate outcome.
Goni began a period of rapid intensification Monday morning (Sunday evening mainland U.S. time) while moving west away from Guam and Saipan. Winds increased 60 mph in the 24 hours from 5 a.m. EDT Sunday to 5 a.m. EDT Monday, according to the U.S. military's Joint Typhoon Warning Center (JTWC). This includes an increase of 40 mph in just six hours late Sunday from 5 p.m. EDT to 11 p.m. EDT. This is the equivalent of jumping from Category 1 to Category 4, with winds peaking at 130 mph.

Forecast Rainfall Through Monday

That's just the first typhoon. What about its twin to the east, Typhoon Atsani?

Twin Typhoons Outlook

Typhoon Atsani: Recurve Out to Sea

Atsani, instead of following in the wake of Goni, is instead much farther east over open waters of the western Pacific Ocean.
This is occurring thanks to an upper-atmospheric high pressure zone to its east.
Once Atsani moves far enough north this weekend, the jet stream should turn Atsani well east of mainland Japan.
(FORECAST: Tokyo | Osaka)
There is a much greater risk of Atsani having some impact on the small Izu and Ogasawara island chains lying south of Tokyo and north of the Northern Marianas. Tropical storm-force winds are likely over the Ogasawara islands, which include the inhabited islands of Chichijima and Hahajima.
Japan's easternmost possession, the tiny atoll of Minamitorishima, recorded a sustained east-southeasterly wind of 36 mph early Thursday (Japan time) well to the north of Atsani's center, according to data from the Japan Meteorological Agency.
(MORE: Expert Analysis | Hurricane Central)

Saipan and Guam Impacted By Heavy Rain, Strong Winds

Over the past weekend, Goni affected Guam and the Northern Mariana Islands as a tropical storm.
Tropical storm-force winds (39 mph or greater) occurred as the center passed through the islands. Off Saipan, a sustained tropical storm-force wind of 43 mph was reported just before 11 p.m. local time (7 a.m. EDT) Saturday. A peak gust of 61 mph was recorded there at 10:23 p.m.
On Guam, Andersen Air Force Base clocked a 49-mph sustained wind at just before 5 a.m. local time Sunday (3 p.m. EDT Saturday), with gusts to 58 mph, as a heavy rain band lashed the northern end of Guam. Guam International Airport near Hagatna, Guam's capital, gusted as high as 46 mph at 5:28 a.m. local time Sunday.
Heavy rain arrived Saturday and continued Sunday, prompting flash flood warnings for Guam and Rota. Guam International Airport reported 13.86 inches of rain Friday through 4 p.m. local time Sunday. (Guam is 14 hours ahead of U.S. Eastern Daylight Time.)
This is the second tropical cyclone to affect Saipan in the last two weeks. The island is still struggling to recover from Typhoon Soudelor.
The Pacific News Center reported about 4,000 households in Saipan, or over 25 percent, have requested assistance from the Federal Emergency Management Agency.
Power outages and a lack of running water and food have plagued the 44-square-mile island about 135 miles northeast of Guam since an intensifying Soudelor hit the island square on Aug. 2.
(WATCH: Saipan Struggles After Soudelor)
Guam's main newspaper, the Pacific Daily News, says some families on Guam are also recovering from typhoon damage – in their case, damage from Typhoon Dolphin back in May. Dolphin's eyewall passed over Guam, delivering gusts as high as 106 mph to the northern end of the island.

Active Northwest Pacific Typhoon Season

Including the two current typhoons and Halola, which migrated westward from the central Pacific basin, there have already been 17 named storms (tropical storm strength or stronger) so far this year in the Northwest Pacific basin. Fourteen of those have become typhoons -- equivalent to hurricanes -- and six of those (Maysak, Noul, Dolphin, Nangka, Soudelor and Atsani) became "super typhoons", packing sustained winds estimated of at least 150 mph.
According to Colorado State University scientist, Dr. Phil Klotzbach, the Northwest Pacific basin had seen record levels of year-to-date tropical cyclone activity through early August, as measured by the accumulated cyclone energy or ACE index.
Meteorologist Chris Dolce contributed to this report.