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Category 6 has moved! See the latest from Dr. Jeff Masters and Bob Henson here.Super Typhoon Nepartak Takes Aim at Taiwan
Residents of Taiwan are turning worried eyes eastwards, where Super Typhoon Nepartak is steaming towards them after putting on a phenomenal display of rapid intensification. Nepartak went from a tropical storm with 70 mph winds on Monday afternoon to a Category 4 super typhoon with 150 mph winds in just 24 hours, as estimated by the Joint Typhoon Warning Center (JTWC). The typhoon took advantage of light wind shear of 5 - 10 knots and extremely warm ocean waters of 31°C (88°F) to fuel its rapid intensification. Unusually warm waters extended to great depth below the storm, creating some of the highest oceanic heat content readings we see for a tropical cyclone--near 150 kJ/cm**2 (Figure 2). Satellite loops from NOAA/SSED and NOAA/RAMMB show a mighty storm with a large area of heavy thunderstorms with cold cloud tops reaching high into the atmosphere, surrounding a 15-mile diameter eye. The storm has taken on an annular appearance, with very little in the way of spiral banding. These type of storms are more resistant to weakening than typical tropical cyclones. The Japanese Meteorological Agency estimated that Nepartak had a central pressure of 925 mb at 2:45 pm EDT Tuesday.
Figure 1. Infrared VIIRS image of Super Typhoon Nepartak at 2:10 pm EDT July 5, 2016. At the time, Nepartak was a Category 4 super typhoon with 150 mph winds. Image credit: NOAA/NASA.
Figure 2. Total Ocean Heat Content (in kilojoules per square centimeter) on July 5, 2016. The past track and forecast track of Super Typhoon Nepartak from the 2 pm EDT July 5, 2016 JTWC advisory are overlaid. After traveling over a long stretch of ocean with very high heat content, Nepartak will be moving over a relatively cool area on Wednesday afternoon (U.S. EDT time.) This reduced heat energy may be responsible for the HWRF model's forecast of a dip in the typhoon's intensity on Wednesday afternoon, followed by a re-strengthening on Thursday morning as the storm passes over another area of relatively high oceanic heat content (see Figure 3). Image credit: University of Wisconsin/CIMSS.
Figure 3. Predicted winds (top) and minimum central pressure (bottom) for Super Typhoon Nepartak made by the Joint Typhoon Warning Center (red) and five computer models at 8 am EDT (12Z) July 5, 2016. The HWRF model (purple) is predicting the typical pattern one might see in an eyewall replacement cycle--a double maximum in the winds (145 kt or 165 mph at 8 pm EDT July 5 and again at 2 am EDT July 7), accompanied by a double minimum in central pressure. However, although the HWRF model is capable of simulating eyewall replacement cycles, this is probably not what is going on in this case, since the zoomed-in graphics from the HWRF model do not show concentric eyewalls forming. Image credit: NOAA/NCEP/EMC.
Nepartak a threat to Taiwan, China, South Korea, and Japan
Nepartak was headed west-northwest at 21 mph on Tuesday evening on a track that will take it very close to Taiwan by Thursday afternoon (U.S. EDT.) Our two top global models for predicting tropical cyclone tracks, the GFS and European models, both predicted that Nepartak would make landfall in Taiwan between 18 - 21 UTC (2 pm - 5 pm EDT) on Thursday. Later that day, a trough of low pressure passing to the north of the storm is expected to pull Nepartak to the north and then northeast, potentially allowing Nepartak to affect the Chinese coast just south of Shanghai, South Korea, and/or Southwest Japan late this week. Nepartak will continue to be over very warm ocean waters of 31°C (88°F) with light wind shear of 5 - 10 knots until about six hours before its expected landfall in Taiwan. Though the total heat content of the ocean will be only roughly half of what the storm fed off during its rapid intensification phase, Nepartak still has nearly ideal conditions for intensification, and will likely become a Category 5 storm on Wednesday.
The Himawari-8 Floater satellite loops have some impressive animations of Nepartak during daylight hours in the Western Pacific.
I'll have a new post on Wednesday.
Jeff Masters
Figure 1. Infrared VIIRS image of Super Typhoon Nepartak at 2:10 pm EDT July 5, 2016. At the time, Nepartak was a Category 4 super typhoon with 150 mph winds. Image credit: NOAA/NASA.
Figure 2. Total Ocean Heat Content (in kilojoules per square centimeter) on July 5, 2016. The past track and forecast track of Super Typhoon Nepartak from the 2 pm EDT July 5, 2016 JTWC advisory are overlaid. After traveling over a long stretch of ocean with very high heat content, Nepartak will be moving over a relatively cool area on Wednesday afternoon (U.S. EDT time.) This reduced heat energy may be responsible for the HWRF model's forecast of a dip in the typhoon's intensity on Wednesday afternoon, followed by a re-strengthening on Thursday morning as the storm passes over another area of relatively high oceanic heat content (see Figure 3). Image credit: University of Wisconsin/CIMSS.
Figure 3. Predicted winds (top) and minimum central pressure (bottom) for Super Typhoon Nepartak made by the Joint Typhoon Warning Center (red) and five computer models at 8 am EDT (12Z) July 5, 2016. The HWRF model (purple) is predicting the typical pattern one might see in an eyewall replacement cycle--a double maximum in the winds (145 kt or 165 mph at 8 pm EDT July 5 and again at 2 am EDT July 7), accompanied by a double minimum in central pressure. However, although the HWRF model is capable of simulating eyewall replacement cycles, this is probably not what is going on in this case, since the zoomed-in graphics from the HWRF model do not show concentric eyewalls forming. Image credit: NOAA/NCEP/EMC.
Nepartak a threat to Taiwan, China, South Korea, and Japan
Nepartak was headed west-northwest at 21 mph on Tuesday evening on a track that will take it very close to Taiwan by Thursday afternoon (U.S. EDT.) Our two top global models for predicting tropical cyclone tracks, the GFS and European models, both predicted that Nepartak would make landfall in Taiwan between 18 - 21 UTC (2 pm - 5 pm EDT) on Thursday. Later that day, a trough of low pressure passing to the north of the storm is expected to pull Nepartak to the north and then northeast, potentially allowing Nepartak to affect the Chinese coast just south of Shanghai, South Korea, and/or Southwest Japan late this week. Nepartak will continue to be over very warm ocean waters of 31°C (88°F) with light wind shear of 5 - 10 knots until about six hours before its expected landfall in Taiwan. Though the total heat content of the ocean will be only roughly half of what the storm fed off during its rapid intensification phase, Nepartak still has nearly ideal conditions for intensification, and will likely become a Category 5 storm on Wednesday.
The Himawari-8 Floater satellite loops have some impressive animations of Nepartak during daylight hours in the Western Pacific.
I'll have a new post on Wednesday.
Jeff Masters
The views of the author are his/her own and do not necessarily represent the position of The Weather Company or its parent, IBM.