Category 5 Super Typhoon Nepartak
is steaming towards a Thursday landfall in Taiwan after putting on a phenomenal display of rapid intensification on Monday and Tuesday. Nepartak went from a tropical storm with 70 mph winds on Monday afternoon to a Category 4 super typhoon with 150 mph winds on Tuesday afternoon, in just 24 hours. Since then, the typhoon has continued to take advantage of light wind shear of 5 - 15 knots and extremely warm ocean waters of 31°C (88°F) to intensify into a ferocious Category 5 storm. These waters are about 1 - 2°C (1.8 - 3.6°F) above average. At 8 am EDT Wednesday, the Japanese Meteorological Agency
estimated that Nepartak had a central pressure of 900 mb, and the Joint Typhoon Warning Center (JTWC) estimated top sustained winds of 175 mph. Over the past two days, unusually warm waters have extended to great depth below the storm, creating some of the highest oceanic heat content readings one sees for a tropical cyclone--near 150 kJ/cm**2 (Figure 2). Satellite loops from NOAA/SSED
show a fearsome storm with huge area of heavy thunderstorms with cold cloud tops reaching high into the atmosphere, surrounding a prominent 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. Figure 1.
MODIS visible satellite image of Super Typhoon Nepartak at 04:50 UTC (12:50 am EDT) July 6, 2016. At the time, Nepartak was a Category 5 super typhoon with 175 mph winds. Image credit: NASA.Figure 2.
Total Ocean Heat Content (in kilojoules per square centimeter) on July 6, 2016. The past track and forecast track of Super Typhoon Nepartak from the 2 am EDT July 6, 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 means that Nepartak will likely be unable to strengthen further on Wednesday. On Thursday morning, typhoon will be passing over another area of relatively high oceanic heat content, which will likely prevent rapid weakening before landfall in Taiwan occurs. Image credit: University of Wisconsin/CIMSS
.Nepartak's impact on Taiwan and China
Nepartak was headed west-northwest at 18 mph on Wednesday morning (U.S. EDT) on a track that will take it over Taiwan on Thursday afternoon. 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 northwest and then north, taking the storm on a path that should bring it just west of Shanghai, China on Sunday, when the storm will likely dissipate. Nepartak will continue to be over very warm ocean waters of 31°C (88°F) with light wind shear of 5 - 15 knots until about 6 - 12 hours before landfall in Taiwan on Thursday. In the final 12 hours before landfall, increasing wind shear, decreasing ocean temperatures, and interaction will land should act to weaken Nepartak to Category 4 strength.Figure 3.
Swath of total rainfall from Nepartak as predicted by the 06 UTC (2 am EDT) Wednesday, July 6, 2016 run of the HWRF model. The model predicted widespread rains of 8 - 16" (light yellow colors) over much of Taiwan and Eastern China. Image credit: NOAA/NCEP/EMC.Figure 4.
Rainfall for the 10-day period ending on July 5, 2016 over China. Rainfall amounts in excess of 15.75" (400+ mm, dark blue color) fell over a large swath of China from Wuhan to just west of Shanghai. Image credit: National Meteorological Center of CMA.Heavy rains a huge concern for Taiwan and China
About 1 - 2" of rain has fallen over Taiwan during the past ten days, so the soils should be able to absorb some of the expected 5 - 15" of rain Nepartak will dump over much of the island. Nevertheless, damaging flooding from the torrential rains of Super Typhoon Nepartak will likely cause tens of millions of dollars in damage to agriculture in Taiwan. The bigger concern for heavy rainfall from Nepartak is in mainland China, though. Exceptionally heavy monsoon rains affected large portions of central and eastern China over the past ten days, bringing rampaging floods that killed at least 170 people and caused over $5 billion in damage. The soils are still saturated from these rains, and Nepartak's rains will trigger additional damaging flooding. The largest city in central China--Wuhan, with a population of 10.8 million--received over 560mm (1.8 feet) of rain over the past ten days, causing widespread chaos there. However, the Wednesday morning run of the HWRF model (Figure 3) showed the heaviest rains of Nepartak would likely miss Wuhan. The main concern is for the region between Wuhan and Shanghai, where another 8 - 16" of rain is likely to fall on regions where more than 8" of rain fell last week.Taiwan's recent typhoon history
If Nepartak hits Taiwan at Category 4 strength, as currently forecast by JTWC, this will not necessarily be catastrophic for the island. Taiwan is no stranger to powerful typhoons, and has endured many strikes by major typhoons without suffering catastrophic impacts. The island was hit by two major typhoons last year: Category 4 Typhoon Dujuan
and Category 3 Typhoon Soudelor
. Typhoon Dujuan made landfall on the island on September 28, 2015, with 140 mph winds, killing three, injuring 376, but causing less than $10 million in damage. Dujuan brought heavy rains to eastern China that caused $652 million in damage, but did not kill anybody there. On August 7, 2015, Typhoon Soudelor
hit Taiwan as a Category 3 storm with 120 mph winds. Souledor killed eight, injured 420, and caused over $100 million in damage. At the peak of the storm, 4.85 million households lost electricity--the largest blackout on record in Taiwan due to a typhoon (previous record: 2.79 million customers blacked out by Typhoon Herb in 1996.) Taiping Mountain in eastern Taiwan's Yilan County saw the heaviest rains from the typhoon, with accumulations peaking at 1,334 mm (52.52".) Souledor brought heavy rains to eastern China that killed 26 people and caused $3.08 billion in damage.Nepartak: Earth's third Category 5 storm of 2016
Nepartak is the third Category 5 storm on Earth so far in 2016, and tied for the second strongest tropical cyclone of the year (by wind speed). The other two Category 5 storms earlier this year were in the Southern Hemisphere: the Southwest Indian Ocean's Tropical Cyclone Fantala
, which topped out with 175 mph winds and a 910 mb central pressure on April 17, and the Southeast Pacific's Tropical Cyclone Winston,
which devastated Fiji on February 20 with sustained winds of 180 mph. Winston's lowest central pressure was 915 mb. Both storms were tied for the strongest tropical cyclones ever observed (by sustained winds) in their respective ocean basins. On average, Earth sees 4 - 5 Category 5 storms per year, with over 50% of these being typhoons in the Northwest Pacific.LinksStunning visible animation of Nepartak from July 6, 2016, from NOAA/RAMMB/Colorado State.
The Himawari-8 Floater
satellite loops have some impressive animations of Nepartak during daylight hours in the Western Pacific.Taiwan radar
I'll have a new post on Thursday.