f. Tropical cyclones 1) OVERVIEW—H. J. Diamond and C. J. Schreck The IBTrACS dataset comprises historical tropical cyclone (TC) best-track data from numerous sources around the globe, including all of the WMO Regional Specialized Meteorological Centers (RSMC; Knapp et al. 2010). IBTrACS represents the most complete compilation of global TC data and offers a unique opportunity to revisit the global climatology of TCs. Using IBTrACS data (Schreck et al. 2014) a 30-year average value for storms (from WMO-based RSMC numbers) is noted for each basin. The tallying of the global TC numbers is challeng- FIG. 4.20. Global summary of TC tracks with respect to SST anomalies (°C) for the 2016 TC season. ing and involves more than simply adding up basin totals, because some storms cross TC basin bound- Compiling the activity using preliminary IBTrACS aries, some TC basins overlap, and multiple agencies data over all seven TC basins (Fig. 4.20), the 2016 are involved in tracking and categorizing the TCs. season (2015/16 in the Southern Hemisphere) had 93

SIDEBAR 4.1: RECORD-SETTING NORTH ATLANTIC HURRICANE MATTHEW—P. J. KLOTZBACH

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S106 | AUGUST 2017 named storms (wind speeds ≥ 34kt or 17 m s−1), which ern North Pacific hurricane seasons were well above is above the 1981–2010 average of 82 TCs (Schreck normal (Section 4f3). et al. 2014), but eight fewer than the 2015 total of 101 Globally, four storms achieved Saffir–Simpson TCs (Diamond and Schreck 2016). The 2016 season category 5 during the year (four fewer than in 2015, also featured 58 hurricanes/typhoons/cyclones (HTC; and three fewer than in 2014): (a) Hurricane Matthew wind speeds ≥ 64kt or 33 m s−1), which is above the in the North Atlantic; (b) Supertyphoon Meranti in 1981–2010 average of 46 HTCs (Schreck et al. 2014). the western North Pacific; (c) Cyclone Fantala in Twenty storms reached major HTC status (wind the South Indian Ocean; and (d) Tropical Cyclone speeds ≥ 96kt or 49 m s−1), which is near the long-term Winston in the Southwest Pacific. Matthew was average of 21. In Sections 4f2–4f8, the 2016 seasonal the costliest hurricane ($10 billion U.S. dollars in activity is described and compared to the historical damages) to strike the U.S. since Hurricane Sandy record for each of the seven WMO-defined hurricane in 2012. Sidebar 4.1 recounts several of the records basins. For simplicity, all counts are broken down that Matthew broke. Supertyphoon Meranti, with by the United States’ Saffir–Simpson scale. Figure maximum sustained winds of 165 kt (85 m s−1), was 4.20 depicts the overall picture of global TCs during the most intense tropical cyclone of the year globally. 2016. The North Atlantic hurricane season was above Sidebar 4.2 describes an unusual situation where Tai- normal (Section 4f2), and both the central and east- wan was impacted by four major typhoons, including

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STATE OF THE CLIMATE IN 2016 AUGUST 2017 | S107