By:
Jeff Masters and Bob Henson
, 10:22PM,GMT on February 19,2016
Figure 1. Radar image from the Fiji weather service showing Tropical Cyclone Winston bringing rain to Fiji at 2121 UTC Friday, February 19, 2016.
On Friday afternoon, Winston was in a nearly ideal environment for intensification, with wind shear a moderate 10 - 15 knots, excellent upper-level outflow channels to both the north and the south, and sea surface temperatures (SSTs) near 31°C (88°F). These SSTs are about 1.5°C (2.7°F) above average. Unusually warm waters extend to great depth, giving Winston a high Tropical Cyclone Heat Potential (TCHP) in excess of 75 kJ/cm^2, a value which is often associated with rapid intensification. Satellite imagery on Friday afternoon showed that Winston had a large area of heavy thunderstorms concentrated in a donut shape around a 18-mile diameter eye, with very few outer spiral bands. This structure may qualify Winston as an "annular" hurricane--a special subclass of hurricanes which are more resistant to weakening than regular hurricanes. With such an annular structure, and with SSTs that will warm even further as Winston moves closer to Fiji, the storm should be able to maintain its Category 5 intensity until landfall.
Figure 2. Visible image from the Himawari satellite of Tropical Cyclone Winston taken at 2100 UTC (4 pm EST) February 19, 2016. At the time, WInston was a Category 5 storm with 165 mph winds. Image credit: Japan Meteorological Agency.
Winston only the 11th Category 5 storm east of Australia since 1970
Winston joins a very select club of Category 5 storms ever recorded to churn the South Pacific waters east of Australia. Since satellite records began in 1970, just eleven Cat 5s (including Winston) have been observed in the South Pacific east of Australia. The strongest tropical cyclones in the Joint Typhoon Warning Center’s records are Zoe (2002/2003) and Monica (2006), which topped out with 180 mph winds (thanks go to Phil Klotzbach of CSU for this stat.) Only two of the ten previous Cat 5s have made landfall as a Category 5. The most recent was last year's Cyclone Pam, which was at its peak strength, with 165-mph Category 5 winds, when it passed over several small Vanuatu Islands to the north of Efate Island, Vanuatu's most populous island (population 66,000.) The other Category 5 landfall was by the strongest tropical cyclone on record in the basin, Cyclone Zoe of 2002. Zoe made a direct hit as a Category 5 storm on several small islands in the Temotu Province of the Solomon Islands with a total population of 1700. There was one other close call, though: the eye of Category 5 Tropical Cyclone Olaf passed 15 miles east of Ta'u, American Samoa, on February 16, 2005, but caused minimal damage.
Figure 3. Track of all Category 5 storms in the South Pacific (east of 135°E) since satellite records began in 1970. The strongest tropical cyclones in the Joint Typhoon Warning Center’s records are Zoe (2002/2003) and Monica (2006), which topped out with 180 mph. Image credit: Michael Lowry, TWC.
Fiji's tropical cyclone history
Category 4 Tropical Cyclone Evan of December 17, 2012 walloped Fiji with sustained winds of 135 mph, as the storm's southern eyewall--the most intense part of the storm--brought hurricane conditions to a long stretch of the north and west coasts of Fiji's main island, Viti Levu. According to a database maintained by NOAA's Coastal Service Center, Evan was the strongest tropical cyclone on record to affect Fiji's main island, with records going back to 1941 (however, accurate satellite records extend back to only about 1990.) Evan did $109 million in damage (2012 dollars) to Fiji, making it the second most destructive storm in their history. The most devastating cyclone to affect Fiji in recent decades was Category 2 Cyclone Kina of January 1993, which killed 23 people and did $100 million in damage (1993 dollars.) The only deadlier storm than Kina was Category 3 Cyclone Eric of 1985, which made a direct hit on the capital of Suva, killing 25.
Figure 4. Tracks of all Category 1 and stronger tropical cyclones to pass within 100 miles of Fiji's main island of Viti Levu since 1941. Evan of 2012 (Category 4 with 135 mph winds) was the strongest cyclone on record to affect Fiji, but Winston of 2016 is stronger. Image credit: NOAA's Coastal Service Center.
Climate change and Fiji
Storm surge from Winston is of particular concern for Fiji, where sea level rise and coastal erosion have already begun to displace people. The nation includes more than 300 islands; some are volcanic in origin, while many of the smaller islands are low-lying coral atolls especially vulnerable to sea level rise. The nation has already assisted one small village, Vunidogolo, in moving to a new location as part of its climate change adaptation program. More than 30 other Fijian villages have been identified as vulnerable.
Although it represents only a tiny share of the world’s fossil fuel emissions, Fiji is doing its part to reduce them. On February 12, Fiji became the first nation on Earth to ratify the global pact on reducing greenhouse emissions that was hammered out at the UN Conference of Parties meeting (COP15) last December in Paris. Fiji has pledged to boost the renewable share of its electricity generation from around 60% in 2013 to near 100% by 2030. Together with energy efficiency improvements, this will reduce Fiji’s carbon dioxide emissions from fossil fuels in 2030 by roughly 30% compared to a business-as-usual approach.
Figure 5. In February 2014, the village of Vunidogoloa on Vanua Levu became the first community in Fiji to relocate because of coastal erosion and flooding attributed in part to climate change. The village moved to higher ground two kilometers inland. Image credit: Nansen Initiative, courtesy UN Office for the Coordination of Humanitarian Affairs.
Links
Radar images from the Fiji weather service
Long radar loop of Winston
Satellite imagery from NOAA/NESDIS.
Fiji weather observations from wunderground.
We'll be back on Saturday with an update on Winston.
Jeff Masters and Bob Henson
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