Dr. Masters co-founded wunderground in 1995. He flew with the NOAA Hurricane Hunters from 1986-1990. Co-blogging with him: Bob Henson, @bhensonweather
By: Dr. Jeff Masters , 04:28 AM GMT die 30o December, anno 2008
As we look back at the weather events of 2008, perhaps the most impressive record set during the year occurred during Hurricane Gustav, which pounded Cuba as a Category 4 hurricane in August. Gustav set a new world record for highest wind gust ever measured in a hurricane. As Gustav passed over the Paso Real de San Diego meteorological station in the western Cuban province of Pinar del Rio, Cuba, on the afternoon of August 30, 2008, a wind gust of 211 mph (94.4 m/s) was recorded (it was originally pegged at 212 mph, but has been "downgraded" to 211 mph after an official review by the World Meteorological Organization). The powerful winds blew down the anemometer, and it is possible that higher gusts occurred after the instrument failed. Not only is this the highest wind speed ever measured in a hurricane, it is the second highest wind gust ever measured at a non-mountain location on Earth, and is the third highest wind gust ever measured on the surface of the planet. The highest wind gust in recorded history is the amazing 253 mph reading recorded on Barrow Island, Australia, during Tropical Cyclone Olivia in 1996. The second highest wind speed ever measured was 231 mph (370 km/hr) on the top of Mt. Washington, New Hampshire, on April 12, 1934, during passage of an extratropical storm. The fourth highest wind gust on record was the 207 mph gust measured in Greenland at Thule Air Force Base on March 6, 1972. The previous highest wind gust measured in a hurricane was 186 mph at Blue Hill Observatory, Massachusetts, during the notorious 1938 "Long Island Express" hurricane.
Figure 1. Anemometer used to measure the record 211 mph gust in Hurricane Gustav. Gustav's powerful winds flattened the instrument against the roof of the observing station. Image credit: Jose M. Rubiera Torres, Instituto de Meteorologia of Cuba.
Is this a believable record?
The instrument used for the measurement in Gustav was a Dines pressure tube anemometer mounted on the roof of the weather office. According to Jose M. Rubiera Torres of Cuba's Instituto de Meteorologia, "The graph is neat and the instrument was in perfect technical working condition. The wind peaked up to 340 km/h and then the anemometer mast fell over the concrete roof of the station's building, sharply interrupting the measurement. The graph [Figure 2], shows that wind gusts were increasing at a regular pace with time, until the instrument broke down when it got to the 340 km/h mark." Dines anemometers have a proven track record of reliability, and have been used in Cuba for over 60 years. A formal committee under the auspices of the World Meteorological Organization (WMO) certified the record in 2009.
Figure 2. Trace of the Dines anemometer used to measure the record 211 mph gust in Hurricane Gustav. Image credit: Jose M. Rubiera Torres, Instituto de Meteorologia of Cuba.
How did such a strong gust occur?
At the time Hurricane Gustav moved over the Paso Real de San Diego meteorological station, the storm was rated a Category 4 hurricane with sustained winds of 150 mph, gusting to 185 mph. When the peak wind gust of 211 mph was measured at 22:35 GMT, the western eyewall of Gustav was over the anemometer site, as seen on Cuban radar (Figure 3). The town of Paso Real de San Diego is at an elevation of about 40 meters, and lies 25 km inland, about 12 km south of a rugged line of mountains up to 700 meters high. The counter-clockwise flow of air around Gustav's eyewall meant that the winds arriving at Paso Real de San Diego were forced to pass over these mountains first. The mountains probably focused and accelerated the winds through gaps between the peaks, and the air accelerated further as it rushed downhill under the force of gravity. Strong downbursts due to collapsing precipitation cores inside Gustav's eyewall probably contributed to the extreme gusts. When hurricanes make landfall, the intense thunderstorm cells that comprise the eyewall sometimes collapse suddenly, sending a downward cascade of intense winds to the surface. When this rush of wind hits the ground, it spreads out in all directions, forming a strong surface wind event known as a downburst. It has been theorized that some of the extreme damage noted in Florida during Hurricane Ivan in 2004 and Hurricane Andrew in 1992 may have been associated with downbursts from collapsing eyewall thunderstorm cells. This behavior may also be responsible for some of the extreme damage in Mississippi from Hurricane Katrina. Animations of infrared satellite imagery available from the University of Wisconsin CIMSS Satellite Blog show that the eyewall of Gustav collapsed during passage over the high mountains to the north of Paso Real de San Diego, but this occurred after the world record wind gust was measured.
Figure 3. Radar image of Hurricane Gustav (top) at 22:25 GMT on August 30 2008, five minutes before the world record 211 mph hurricane wind gust was measured. The site of the Paso Real de San Diego meteorological station where the record was set is marked with a red dot. A topographic map (bottom) shows the line of mountains up to 1200 meters high that lies just north of the town. The counter-clockwise flow of air around the eye of Gustav brought the strongest winds of Gustav across the mountain range then downhill to Paso Real de San Diego. Radar image credit: Instituto de Meteorologia of Cuba. Topographic map image credit: Wikipedia.
Note: this post was updated in 2010 to reflect the official WMO review of Gustav's wind gust, plus the addition of the new World Record wind gust set in TC Olivia in 1996.
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