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Another Category 5 Cyclone: Super Typhoon Soudelor

By: Bob Henson 1:36 AM GMT on August 04, 2015

Super Typhoon Soudelor vaulted to Category 5 status on Monday, making it the planet's sixth (at least--see below) Category 5 storm of the year. At 2:00 pm EDT Monday, Soudelor’s sustained winds were estimated at 180 mph, with the strength unchanged in the 8:00 pm EDT Monday update from the Joint Typhoon Warning Center (JTWC). For the year thus far, Soudelor is Earth’s strongest tropical cyclone in terms of estimated wind speed. The Weather Channel’s Nick Wiltgen notes that Soudelor’s estimated central pressure of 900 mb is the lowest in a typhoon since last year’s Super Typhoon Vongfong, also 900 mb. Five prior Category 5 storms this year were described and illustrated in a May 19 post. They include Tropical Cyclone Eunice, Cyclone Pam, Super Typhoon Maysak, and Super Typhoon Noul. Update: Our initial survey of JTWC products showed that Cyclone Bansi fell short of Category 5 status. However, JTWC data for Cyclone Bansi archived by RAMMB-CIRA indicate that Bansi's estimated winds peaked at 140 knots (about 160 mph) at 0000 GMT on January 13. If we include Bansi, then we're now up to a startling seven Category 5 storms so far in 2015. This compares to a yearly average of 4.6 Category 5 storms for the period 1990-2014. It's not out of the question we could break the record total of 12 Category 5 storms notched in 1997, when--much like this year--a strong El Niño was ramping up. Thanks to wunderground member 1900hurricane for bringing Bansi data to our attention.

Models are in quite close agreement on keeping Soudelor rolling along a steady west-northwest track around the southwest side of a strong upper-level high. In its 0300 GMT Tuesday forecast update, the JTWC projected that Soudelor would strike the northern end of Taiwan on Friday or Saturday local time, potentially as a Category 3 or 4 storm. On such a track, Soudelor would move very close to Taiwan’s largest city, Taipei. The island’s rugged topography can lead to massive rainfall and hugely destructive flooding when strong typhoons make landfall, so Soudelor will have to be watched very closely.

Figures 1 and 2. These images of Super Typhoon Soudelor (Figure 1= infrared, Figure 2 = visible) show incredible detail collected at 1633 GMT Monday (12:33 pm EDT) by the Visible Infrared Imaging Radiometer Suite (VIIRS) sensor aboard NASA’s Suomi NPP satellite. For an animated-GIF version that switches between these two images, see the embedded tweet from Ari Salsalari (The Weather Channel) at bottom of this post. Image credit: NOAA/NASA, courtesy Dan Lindsey, RAMMB/CIRA, and Stu Ostro, Weather Channel.

Along with the strikingly crisp eyewall, the images of Soudelor in Figures 1 and 2 reveal a “cloud cliff”--a sharp, distinctly linear feature that abuts the northeast side of the eyewall. The cause of such cloud cliffs is unknown, but it is not uncommon to see them in super typhoons over the western Pacific. Similar features were observed in 2012 in Super Typhoon Bopha (visible on the south side of the eye in this blow-up image from the University of Wisconsin CIMSS Satellite Blog), and in Super Typhoon Jelawat (visible on the north side of the eye.) For several images showing a cloud cliff in last year’s Typhoon Neoguri, see this July 2014 post by Jeff Masters.

Figure 3. An infrared image of the increasingly sheared Tropical Storm Guillermo, collected by the GOES West satellite at 0000 GMT Tuesday (8:00 pm EDT Monday). Image credit: NOAA/NESDIS.

Elsewhere in the tropics
Moving into increasingly hostile conditions, Tropical Storm Guillermo continued its slow weakening trend on Monday. Guillermo’s sustained winds were reduced to 65 mph in the 3:00 pm EDT Monday advisory from the Central Pacific Hurricane Center. As expected, westerly wind shear is ramping up along Guillermo’s track as the storm gains latitude, with vertical shear values likely to exceed 30 mph by Wednesday. With regular input from hurricane-hunter reconnaissance flights, computer models have nudged Guillermo’s west-northwest track a bit further away from the Hawaiian islands. Tropical storm watches may be issued for parts of the state, although it appears that large swells and localized heavy rains will be the main threat from Guillermo. The scenario is very reminiscent of Tropical Storm Flossie, which moved along a similar track paralleling and just north of the Hawaiian Islands while weakening from a tropical storm to a tropical depression. Meanwhile, a new system in the Northeast Pacific, Invest 92E, shows potential for developing into a tropical storm later this week, but it is unlikely to affect any major land areas.

In the Atlantic, tenacious Invest 95L is now hugging the coast of Georgia as it parallels the southeast U.S. coast on its slow northeastward path. Though still poorly organized, 95L brought heavy rains to the central Florida peninsula, especially across the Tampa Bay area, with flooding a concern throughout the day on Monday. Tampa notched 4.39” of rain on Monday, eclipsing the daily record of 2.57” from 1913. These rains came on top of 3.89” observed in Tampa on Saturday and 11.84” through July (most of it during the last two weeks of the month). Chances of 95L developing into a tropical cyclone while moving so close to the southeast U.S. coast are minimal. By Wednesday, 95L should be accelerating out to sea off the North Carolina coast.

A large and healthy tropical wave was just coming off the African coast on Monday night, with some hints that it could develop into an invest-worthy system over the next several days. For more on what’s brewing there and elsewhere, check out this afternoon’s post from WU blogger Steve Gregory. I’ll have a new post by Tuesday afternoon.

Bob Henson


The views of the author are his/her own and do not necessarily represent the position of The Weather Company or its parent, IBM.