the second week of October 2005, a large and complex area of low pressure developed over the western Atlantic and eastern Caribbean with several centers of thunderstorm activity. This area of disturbed weather southwest of Jamaica slowly organized into Tropical Depression Twenty-four on October 15.
It reached tropical storm strength at 5 am EDT October 17 (09:00 UTC), making it the first storm ever to use the 'W' name since alphabetical naming began in 1950, and tying the record for most storms in a season with 1933. Moving slowly over warm water with little wind shear, it strengthened steadily and became a hurricane on October 18. This made it the 12th hurricane of the season, tying the record set in 1969.
Hurricane Wilma began to intensify rapidly during late afternoon on October 18 around 4 pm EDT. Over a 10 hour period Hurricane Hunter aircraft measured a 78 mbar (2.30 inHg) pressure drop. In a 24-hour period from 8 am EDT October 18 (12:00 UTC) to the following morning, the pressure fell 90 mbar (2.65 inHg). In this same 24-hour period, Wilma strengthened from a strong tropical storm with 70 mph (110 km/h) winds to a powerful Category 5 hurricane with 175 mph (280 km/h) winds (Some NHC inside sources suggest that Wilma actually had 185 mph (295 km/h) at its peak [2]). (In comparison, Hurricane Gilbert of 1988 – the previous recordholder for lowest Atlantic pressure – recorded a 78 mbar (2.30 inHg) pressure drop in a 24 hour period for a 3 mbar/h pressure drop.) This is a record for the Atlantic basin and is one of the most rapid deepening phases ever undergone by a tropical cyclone anywhere on Earth - the record holder is 100 mbar (hPa) by Super Typhoon Forrest in 1983. [3] With Hurricane Wilma, 2005 became the first year on record to host three category 5 storms in the Atlantic basin (the other two being Hurricane Katrina and Hurricane Rita).
Visible image of Hurricane Wilma near record intensity with a central pressure of 882 millibars. Image captured by satellite at 1315Z (9:15 EDT) on October 19, 2005.
During its intensification on October 19, the eye's diameter shrank to as small as 1.5 to 2.0 nautical miles - one of the smallest eyes ever seen in a tropical cyclone. [4]
Quickly thereafter, Wilma set a record for the lowest pressure ever recorded in an Atlantic hurricane when its central pressure dropped to 884 mbar (26.10 inHg) at 8 am EDT (12:00 UTC) on October 19, then dropped again to 882 mbar (26.045 InHg) three hours later before rising slowly in the afternoon (while remaining a Category 5 hurricane). In addition, at 11 pm EDT that day (03:00 UTC October 20), Wilma's pressure dropped again to 894 mbar (26.40 inHg) – as the storm weakened to a Category 4 with winds of 155 mph (250 km/h). Wilma was the first hurricane ever in the Atlantic Basin, and possibly the first tropical cyclone in any basin, to have a central pressure below 900 mbar (26.58 inHg) while at Category 4 intensity (in fact, only two other recorded Atlantic hurricanes have ever had lower pressures even at this point, these two storms being previous record holder Hurricane Gilbert of 1988 and the Labor Day Hurricane of 1935).
Photo taken from the balcony of a Cancún hotel at the height of the storm.
While Wilma was the most intense hurricane (i.e. a tropical cyclone in Atlantic, Central Pacific or Eastern Pacific) ever recorded, there have been many more intense typhoons in the Pacific (see link in the next section). Super Typhoon Tip is the most intense tropical cyclone on record at 870 mbar (25.69 inHg).
Though the pressure of a hurricane is the best indicator of its strength since it can be precisely measured whereas winds have to be estimated, it is still important to note that it is actually the difference in the hurricane's pressure and that of its environment that actually gives it its strength. This difference in pressure is known as the "pressure gradient" and it is this change in pressure over a distance that causes wind. The bigger the change is, the faster the winds generated will be. If two hurricanes have the same minimum pressure, but one is in an area of higher ambient pressure than the other, that one is in fact stronger. That hurricane had to work harder, so to speak, to get its pressure that low, and its larger pressure gradient would make its winds faster.
For this reason, it is possible that in reality, Hurricane Wilma may not really be the strongest hurricane on record, despite having the lowest pressure ever. Hurricane Wilma existed within an area of ambient pressure that was unusually low to begin with. This was especially visible given how slow Wilma’s winds were for its pressure. 175 mph may seem incredibly fast, but for an 882 mb (26.05 inches) hurricane it is actually quite slow. In comparison, Hurricane Gilbert, the previous record holder, had a pressure of 888 mb (26.22 inches) but had winds of 185 mph. In fact, at one point after Wilma’s period of peak intensity, it had a pressure of 894 mb (26.40 inches) but was actually not even a Category 5, with winds of just 155 mph. Before Wilma, it had been unheard for a storm to go under 900 mb (26.58 inches) and not be a Category 5. These exceptionally slow winds indicate that the low ambient pressure surrounding Wilma caused the 882 mb (26.05 inches) pressure it achieved to be less of an accomplishment than usual, weakening the pressure gradient. Therefore, it is entirely possible that Hurricane Gilbert, and not Wilma, is still the strongest North Atlantic hurricane on record.
On October 21, Hurricane Wilma made landfall on Mexico's Yucatán Peninsula as a powerful category four hurricane, with winds in excess of 150 mph. The hurricane's eye first passed over the island of Cozumel, and then made an official landfall near Playa del Carmen in the state of Quintana Roo around midnight on October 22 EDT with winds near 140 mph. Portions of the island of Cozumel experienced the calm eye of Wilma for several hours with some blue skies and sunshine visible at times. The eye slowly drifted northward, with the center passing just to the west of Cancún, Quintana Roo. Some portions of the Yucatán Peninsula experienced hurricane force winds for well over 24 hours. The hurricane began accelerating in the early morning hours of October 23, exiting the NE tip of the Yucatán Peninsula and entering the Gulf of Mexico as a Category 2 storm.
Radar image of Hurricane Wilma as it slowly drifted inland over the NE Yucatán Peninsula with winds of 140 mph.
Hurricane Wilma's southeast eyewall passed the greater Key West area in the lower Florida Keys in the early morning hours of October 24, 2005. At this point, the storm's eye was approximately 35 miles (56 kilometres) in diameter, and the north end of the eye wall crossed into the south and central section of Palm Beach County as the system cut a diagonal swath across the southern portion of the Florida peninsula. Several cities in the South Florida Metropolitan Area, which includes Palm Beach, Fort Lauderdale and Miami, suffered severe damage as a result of the intense winds of the rapidly-moving system. The center of the eye was directly over the South Florida Metropolitan Area at 10:30 a.m. on Monday, October 24.
Flooding caused by Wilma on Key Haven, island suburb of Key West, Florida
After the hurricane had already passed, there was a 10' storm surge from the Gulf of Mexico that completely inundated a large portion of the lower Keys. Most of the streets in and near Key West were flooded with at least 3' of salt water, causing the destruction of tens of thousands of vehicles. Many houses as well were flooded with 1-2' of sea water.
Hurricane Wilma reintensifies after encountering the Gulf Loop Current.
Despite significant wind shear in the Gulf, Hurricane Wilma regained some strength before making a third landfall just north of Everglades City, Florida, near Cape Romano, at 6:30 am EDT October 24 (10:30 UTC) as a Category 3 hurricane. The reintensification of Hurricane Wilma was due to its interaction with the Gulf Loop Current. At landfall, Wilma had sustained winds of 125 mph (200 km/h). Over the Florida peninsula, Wilma weakened slightly to a Category 2 hurricane, and exited Florida and entered the Atlantic at that strength about six hours later.
Unexpectedly, Wilma regained strength over the Gulf Stream and once again became a Category 3 hurricane north of the Bahamas and regained all the strength it lost within 12 hours. However, on October 25, the storm gradually began weakening and became extratropical late that afternoon south of Nova Scotia - while still at hurricane strength and affecting a large area of land and water with stormy conditions.
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Tema: Consulta sobre el Huracán Wilma (Leído 1404 veces)