The 1992 hurricane season had been suspiciously quiet through mid August, until finally the first named storm-Andrew was formed. Andrew was formed by a Tropical Wave near the Cape Verde Islands. A tropical wave is defined as a trough or cyclonic curvature maximum in the trade-wind easterly. A tropical wave may reach maximum amplitude in the lower middle troposphere. In other words, it is an area of low pressure that travels over the ocean during anytime of the year. This has a chance of developing into a tropical depression, tropical storm, or even a hurricane. Hurricane Andrew crossed Western Africa to the tropical Northern Atlantic Ocean on August 14, 1992. The wave traveled to the west at about 20 knots (kt). It was steered by a very quick and deep easterly current on the south side of an area of high pressure. The tropical wave passed to the south of the Cape Verde Islands the very next day. Convection subsequently became much more focused in a region of cloud rotation. Narrow bands of clouds developed around the center of rotation on August 16, 1992. At 1800 hours on the 16th day of August, the National Hurricane Center confirmed that the tropical wave had developed enough to be classified as a tropical depression.
The tropical depression was initially embedded in an environment of easterly vertical wind shear, or wind that prevents development of a cyclone. By midday on the 17th day of August, however, the shear diminished. The depression grew stronger and, at 12:00, it became Andrew, the first Atlantic tropical storm of the 1992 hurricane season. Form this point in time, the tropical storm continued moving very quickly to the west-northwest. This course was in the general direction of the Lesser Antilles.
Between the days of August 17th and 20th, the tropical storm passed south of the center of a high pressure over the eastern Atlantic. Steering currents carried Andrew closer to a strong upper-level low pressure system centered about 500 nautical miles to the east-southeast of Bermuda. The currents also carried Andrew to a trough that extended southward from Andrew for a few hundred miles. These currents slowly but surely changed and Andrew decreased in speed on a course which became northwesterly. With the luck of this change in heading, Andrew spared the Lesser Antilles. The change in track also brought the tropical storm directly into a place of strong southwesterly vertical wind shear and quite high surface pressures to its north. At this time, the maximum wind speed of Andrew varied little. However, right after this time a rather remarkable evolution occurred. Satellite shots show that Andrew produced deep convection only sporadically for several days, mainly in several bursts of about 12 hours duration. Finally, the very deep convection did not persist very long at all. Instead, Andrew had the low-level circulation taken away from him by the strong southwesterly flow in upper levels of the atmosphere. Reconnaissance aircrafts took a flight into Andrew and on the 20th day of August, found that the cyclone had dissipated enough to be a low-level circulation center. His central pressure rose considerably. However, the flight data indicated that Andrew kept a very vigorous circulation aloft. Andrew was estimated on 20th of August to have been a tropical storm with 40 kt maximum sustained winds and an had a very astonishingly high central pressure of 1015 millibars. Tropical Storm Andrew headed towards the northwest for five days with little strengthening.
Very significant changes in environment near Andrew began on the 20 day of August. Satellite pictures in the water vapor channel indicated that the low aloft to the east-southeast of Bermuda weakened and split. The brunt of the low pressure opened into a trough which retreated towards the north direction. That evolution minimized the wind shear over Hurricane Andrew. The rest of the low pressure dropped southward to a position just southwest of Hurricane Andrew. This is where his circulation deepened the upper-level outflow over the tropical cyclone. At the same time, a strong dome of high pressure formed near the southeast coast of the United States. A ridge was built eastward from the high into the southwestern Atlantic with its axis lying just a little bit to the north of Andrew. The steering flow over the tropical storm became much more easterly. Andrew turned toward the west and accelerated to about 16 kt. These changes quickly intensified Hurricane Andrew.
Andrew reached hurricane strength in the early morning hours of August 22nd as a minimal hurricane with winds of 75 mph. Andrew was the first Atlantic hurricane to form from a tropical wave in nearly two years. An eye began to form that morning, and the rate of Andrew 's strengthening increased. Hurricane Andrew weakened when it passed over the western part of the Great Bahamas Bank, and his pressure rose to 941 mb. However, the hurricane rapidly reintensified during the last few hours before making landfall again when it moved over the Straits of Florida. In the morning of the 22nd, winds were at 75 mph, but by evening, winds were up to 110 mph, and by noon it had winds of 135 mph. Andrew quickly exploded from a tropical storm to a category 4 major hurricane in only 30 hours. By noon on the 23rd, Andrew was at its peak intensity with winds of 150 mph. By now, it was moving close to due west at 15 mph on a course that would carry it right through the Bahamas and Florida. Warnings were then posted, and they prepared for a twenty-three foot storm surge on the Bahamian shores. Around this time, residents along the entire Florida coast had their eyes studying the path of Andrew. Grocery stores overflowed with customers and residents stockpiled for necessities. As Andrew came closer, the forecasters' work continued around the clock. However, as the hours rolled by, they realized that they were situated at ground zero. Across South Florida, the word was out that Andrew was coming and with very scary strength.
The total evacuation was estimated at around 700,000 people in South Florida. With every weather bulletin, the news worsened. Across much of the target zone, many people were still wondering if they should stay or go. Around midnight, while Andrew was still more than 100 miles east of Miami, aircraft reconnaissance reports and satellite images confirmed that the storm's eye was developing an eyewall, a thing that appears in very intense hurricanes. As the storm strengthened, its eye would contract and then form a new outer eyewall that would eventually choke out the inner eye. As this replacement began, the storm weakened slightly and then strengthened while it contracted. As the hours began to proceed midnight, Andrew moved in on South Florida, and the radar images told the entire story. It was not a very large hurricane; the winds of the hurricane force intensity extended only thirty miles in all directions around the eye. Also, forecasters observed that Andrew's rainbands lacked the heavy precipitation usually found in hurricanes. However, it was known that Andrew was a very intense hurricane and the winds would be very extreme around the vicinity of landfall. Unfortunately for Dade County residents, they had no concept of how destructive 140 mile per hour winds can be.
Finally, at around 4:30 a.m. on August 24, the west eyewall of the storm moved over Biscayne Bay. The tract would take it through Cutler Ridge, Homestead, and other portions of South Dade County. The maximum sustained winds were around 145 mph, and it had gusts around 145 mph. With a forward speed of 18 mph, it traveled due west with a pressure of 27.91 inches. By 8:00 am, Andrew had passed over Naples and was moving offshore, and the story of his trouble over Florida had ended. After Andrew's quick pre-dawn pounding on Florida, news of this astonishing destruction and possible future course filled television screens all across America. Across South Florida, however, many people didn't receive many of these broadcasts because they were without power. Less than twenty-four hours later, Andrew was back up to category 4 strength. He continued to move closer and closer to the lower reaches of Louisiana. The course gradually turned to the northwest, prompting hurricane warnings and many evacuations. About 1.25 million people evacuated Louisiana for Andrew. He poised the threat to strike the Louisiana coast with winds still sustained at 140 mph. Fortunately, its track took it well west of New Orleans.
For a brief time, Andrew slowed and weakened somewhat, and then made landfall again between New Iberia and Lafayette, Louisiana. The maximum sustained winds were reported to be at 115 mph with gusts at 160 mph. After making landfall, it turned its track to the northeast and lost energy rapidly. Within 10 hours, it became a tropical storm. Damages throughout the area were extensive. Andrew and its remnants produced heavy rains that exceeded 11.92 inches, recorded in the city of Hammond. Along with his winds, storm surge, and heavy rains, Andrew spawned numerous tornadoes. Though Louisiana had a reeling aftermath of the hurricane, it didn't compare to Florida's. The highest maximum sustained winds on landfall for Andrew were 145 mph with gusts over 175 mph. Some people in Homestead, Florida claimed that the very low air pressure had sucked the water from their toilets. Tornadoes were blamed for two deaths and about thirty injuries. As Andrew dissipated, its core dissolved into many thunderstorms that caused further problems.