World: Maximum Surface Wind Gust (Tropical Cyclone)

References

WMO Evaluation Panel of experts in charge of global weather and climate extremes within the WMO Commission for Climatology (CCl)consisted of the following experts: Dr Pierre Bessemoulin, MeteoFrance and President of CCl; Dr Tom Peterson, NOAA National Climatic Data Center; Dr Blair Trewin, Australian Bureau of Meteorology; Dr Jose M. Rubiera Torres, Cuban Instituto de Meteorología; Dr John (Jack) Beven, USA National Hurricane Center; Dr John King, British Antarctic Survey; Dr Randy Cerveny, Arizona State University and CCl Rapporteur of Climate Extremes.

Discussion

In "A review of extreme wind gusts at Barrow Island during Tropical Cyclone Olivia, 10 April 1996" by Joe Courtney and Steve Buchan: "The Barrow Island anemometer was a heavy duty three-cup Synchrotac anemometer positioned 10 m above ground level and 64 m above sea level, mounted on a mast as shown in Figs. 3 and 4. The mast was a cyclone-rated Hills telescoping 10m tower comprising 2 x 4.5m sections with a 1m mast extension. Each section was guyed with 3 x 6mm stainless steel wires.

The instrument was sited towards the centre of the island about 4 km from the coast to the southeast and about 7 km inland from the south southwest, the direction of the strongest wind gusts. The instrument is well exposed in all directions, the site is slightly elevated above the surrounding reasonably level terrain and the vegetation is very low.

The instrument was in good working order and was regularly inspected with comparisons made against a hand-held anemometer. The instrument was owned by WAPET, which has since been transferred to Chevron. Maintenance was performed by WNI Science and Engineering (now known as MetOcean Engineers). Synoptic data was ingested into the Bureau of Meteorology system for forecasting and climate applications.

The peak wind gust measurement was one of five extreme gusts during a series of 5-min time periods. Gusts of 199, 220 and 202 knots (369, 408, 374 km/h) were measured followed by a series of four lower values (minimum of 114 knots (211 km/h)) which were then followed by two more extreme gusts of 187 and 161 knots (347 and 298 km/h) in the 5-min time intervals. The elapsed time between gust maxima was 30 min, representing a scale of 8 nm (15 km) compared to the eye diameter of 40 nm (75 km). The 5-min average winds showed maxima and a minimum at the same time periods as the gusts. The pattern and scales suggests that a mesovortex was imbedded in the already strong eyewall mean winds (5-min mean maximum wind = 95 knots (176 km/h)). The extreme gusts represented extreme gust factors of 2.27-2.75, nearly twice the average gust factor throughout the storm of 1.33. This clearly suggests that some process other than mechanical turbulence is important during this period.

Previous record: 94.4 m/s (211.3 mph)at Paso Real de San Diego meteorological station in Pinar del Rio, Cuba