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Category 3 Tropical Cyclone Debbie Pounding Queensland, Australia

By: Jeff Masters and Bob Henson 4:23 PM GMT on March 27, 2017

Tropical Cyclone Debbie is battering Northeast Australia’s Queensland coast with torrential rains and high winds as the storm heads west-southwest at about 5 mph towards an expected landfall near 3 pm EDT (19 UTC) Monday. Debbie intensified into a Category 3 storm with 115 mph winds on Monday morning U.S. time, and satellite images on Monday morning showed an impressive storm with a well-defined eye surrounded by eyewall thunderstorms with very cold cloud tops that were increasing in intensity.

Winds at Hamilton Island in the south eyewall of Debbie were 85 mph (10-minute average), gusting to 113 mph at 2:30 am local time Tuesday (12:30 pm EDT or 16:30 UTC Monday), and winds at Hardy Reef were sustained at 63 mph, gusting to 93 mph at 11 pm local time. According to storm surge expert Dr. Hal Needham, storm surge levels were beginning to build on Monday afternoon (local time) at several sites along the Queensland coast. Laguna Quays, Mackay and Dalrymple Bay all reported storm surge levels exceeding 0.5 m (1.64 ft).  Water levels should increase through the night as Debbie approaches the coastline, with storm surge exceeding 2.5 m (8.2 ft) in localized areas between Bowen and Mackay. Debbie has favorable conditions for intensification, with light wind shear and warm ocean temperatures of 28 - 29°C (82 - 84°F.) However, Debbie does not have much time to intensify before landfall, and will likely be at Category 3 strength then. Recent runs of the HWRF model predict that Debbie will dump a large area of 8+ inches of rain near the coast, which is likely to cause considerable flooding and agricultural damage.

Figure 1. Tropical Cyclone Debbie nearing landfall as seen by radar at 16:00 UTC (12 pm EDT) March 27, 2017. Image credit: Australia Bureau of Meteorology.

Figure 2. Track of Tropical Cyclone Debbie as projected by the Australian Bureau of Meteorology at 12:10 am Tuesday, March 28, 2017 (10:10 am EST Monday). Debbie is a “4” on the Australian tropical cyclone intensity scale, whose 1-to-5 numbering system has lower intensities than the Saffir-Simpson equivalent familiar to Americans, which uses 1-minute sustained winds. According to BOM, Debbie’s top 10-minute sustained winds at 10:10 am EST Monday were 175 km per hour (108 mph), and Debbie’s top 1-minute winds were 115 mph, corresponding to a low-end Category 3 storm on the Saffir-Simpson scale. Image credit: BOM.

Figure 3. Tropical Cyclone Debbie, as seen on Monday afternoon (local time), 03:50 UTC March 27, 2017. At the time, Debbie was an intensifying Category 2 storm with 105 mph winds. Image credit: NASA.

Tropical cyclone history of the Queensland, Australia coast
According to NOAA’s historical Hurricane Tracks tool, Queensland has been hit by nine tropical cyclones of Category 3 or higher strength on the Saffir-Simpson Scale since 1989. Four of these storms have hit since 2011:

Tropical Cyclone Marcia hit central Queensland near Shoalwater Bay as a Category 4 storm with 145 mph winds on February 20, 2015, causing $590 million in damage. No fatalities were reported.

Tropical Cyclone Nathan hit far northern Queensland as a Category 3 storm with 115 mph winds on March 19, 2015, causing $57 million in damage.

Tropical Cyclone Ita hit Cape Flattery, Queensland as a Category 4 storm with 145 mph winds on April 12, 2014, causing over $1 billion in damage to agriculture. Ita killed 40 people in the Solomon Islands while it was forming (thanks go to WU member elioe for this correction.)

Queensland suffered a devastating blow on February 3, 2011, when Tropical Cyclone Yasi made landfall in northern Queensland as a Category 4 storm with 155 mph winds, killing 1 and causing $2.5 billion in damage (2011 dollars.) According to EM-DAT, Yasi was the most damaging tropical cyclone in Australian history.

The Australian Bureau of Meteorology has a nice summary of the major to storms to impact Queensland before 2011.

The Atlantic’s first Invest of 2017, 90L, not likely to develop
A large area of low pressure a few hundred miles east of the Bahamas was designated as the season’s first Atlantic “Invest”—Invest 90L—by NHC on Sunday. 90L is over waters that are near 24°C (75°F)—barely warm enough to support formation of a subtropical depression or subtropical storm. Satellite loops on Monday morning showed that 90L had a vigorous circulation, but little in the way of organized heavy thunderstorm activity. With wind shear a very high 50 - 70 knots, and with the low headed northeastwards over cooler waters, development into a subtropical storm is unlikely. 90L will pass a few hundred miles southeast of Bermuda on Tuesday. According to NOAA’s Historical Hurricane Tracks, the only March tropical cyclone ever recorded in the Atlantic was a Category 2 hurricane that passed through the Lesser Antilles on March 8, 1908.

Hurricanes Matthew and Otto get their names retired
The World Meteorological Organization (WMO) announced on Monday that two major hurricanes in the Atlantic from 2016—Matthew and Otto—will get their names retired from the active list of hurricane names. Matthew and Otto are the 81st and 82nd names to be removed from the Atlantic list. The WMO will replace Matthew with Martin and Otto with Owen when the 2016 lists are used again in 2022.

Bowen Australia radar loop courtesy of Brian McNoldy.

Jeff Masters and Bob Henson


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