P. Storm Histories of Hurricanes Charley and Katrina
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These are summaries of the storms' histories that can be found at the National Hurricane Center (NHC) Website under Hurricane History. We will be using these storms as examples throughout the SCOOP tutorial.
Hurricane Katrina (2005)
(Adapted from the NHC Tropical Cyclone Report)
Hurricane Katrina was one of the most costly, deadly, and powerful storms in the history of the United States. The storm was classified as Tropical Depression Twelve at 1800 UTC 23 August over the southeastern Bahamas. It strengthened as it moved slowly to the northwest over the Bahamas, becoming Tropical Storm Katrina at 1200 UTC 24 August. A middle to upper tropospheric ridge over the northern Gulf of Mexico turned the storm westward, and the cyclone reached hurricane status at 2100 UTC 25 August, just before making landfall on Florida's southeast coast as a Category 1 hurricane, with maximum sustained winds of 70 knots. As the storm moved inland, the eye became better defined, but the storm weakened to Tropical Storm status as it re-entered the Gulf of Mexico at approximately 0500 UTC 26 August.
Within an hour it regained hurricane status with maximum sustained winds of 65 knots. By 0600 UTC 27 August, the hurricane had maximum sustained winds of 95 kt. By the end of 27 August, Katrina had become a Category 3 Hurricane with 100 kt winds and had doubled in size. The storm continued to grow in intensity, becoming a Category 5 with winds of 145 kt by 1200 UTC 28 August. By this time, the storm was about 170 mi southeast of the mouth of the Mississippi River. Katrina turned northward early 29 August, and due to the deterioration of the inner eye wall and formation of a completely new outer eyewall, weakened to a Category 3 with sustained winds of 100 kt by the time it made landfall near Buras, Louisiana at 1110 UTC 29 August. A few hours before the center made landfall, the storm was likely a Category 4 with maximum sustained winds of 115 kt.
Once it made landfall, Katrina quickly diminished in strength, falling to a Category 1 hurricane by 180 UTC 29 August. In six hours it fell to tropical storm status near Meridian, Mississippi, and was a tropical depression over the Tennessee Valley at 1200 UTC 31 August. It finally was absorbed as an extratropical low pressure system within a frontal zone layer over the eastern great lakes.
Measurements of storm surge data were complicated by many factors, including the widespread failure of tide gauges and the destruction of most buildings along the coast from which still-water marks could have been measured. Fortunately, some data was still collected under the direction of the Federal Emergency Management Agency (FEMA). The maximum high water mark observation of storm surge was 27.8 ft at Pass Christian. Data indicated a storm surge of 24 to 28 ft along the Mississippi coast, centered at St. Louis Bay and spreading 20 miles wide. Furthermore, the storm surge was 17 to 22 ft along the eastern half of the Mississippi coast. The surge went at least six miles inland along the coast of Mississippi, and twice that along the bays and rivers. There was a storm surge of 10 to 15 ft along coasts of western Alabama, and a maximum surge of 10 ft in eastern Alabama. When all was said and done, about 80% of the city of New Orleans was flooded, some areas up to 20 ft.
The incredible storm surge from Katrina can be explained by its massive size. In addition, Katrina generated large northward-propagating swells during its time as a Category 5 storm, about 24 hours before landfall. A measurement by the National Data Buoy Center (NDBC) reported a significant wave height (found as the average of the upper one-third of wave heights) of 30 ft at 0000 UTC 29 August, and a peak significant wave height of 55 ft at 100 UTC 29 August, matching the largest significant wave height ever recorded by a NDBC buoy.
Public Advisory for August 29, 2008 at 2am
Hurricane Charley (2004)
(Adapted from the NHC Tropical Cyclone Report)
Charley started off the west coast of Africa as a tropical wave on 4 August 2004. It strengthened as it made its way through the Caribbean, past Jamaica, and over Cuba. The eye left Cuba by 0600 UTC 13 August and moved toward the lower Straits of Florida, where Charley weakened slightly. Charley turned northward and its maximum winds were near 95 kt when it passed over the Dry Tortugas around 1200 UTC 13 August.
At this point, Charley was headed northward, but it “came under the influence of an unseasonably strong mid-tropospheric trough that had dug from the east-central United States into the eastern Gulf of Mexico”. It was because of this trough that the hurricane started heading north-northeastward toward the southwest coast of Florida. By 1400 UTC 13 August, the maximum winds were near 110 kt. Three hours later, they were Category 4 strength winds of 125 kt. The eye actually shrank before landfall, which caused the intense winds to be concentrated to a very small area, which did extreme damage. Around 1945 UTC 13 August, Charley made landfall on Florida’s southwest coast near Cayo Costo. The maximum sustained winds at landfall neared 130 kt. A storm surge of 4.2 feet was measured by a tide gauge in Estero Bay, near Fort Myers Beach. On tide gauges on the Caloosahatchee River, near Fort Myers, storm surges of 3.4 and 3.6 feet were measured. “There were also visual estimates of storm surges of 6 to 7 feet on Sanibel and Estero Islands” (Pasch 3). Charley passed over Punta Gorda and Port Charlotte with devastating results and continued heading north-northeastward over central Florida. Even though the hurricane sped up, a huge amount of destruction occurred across the state. When the hurricane crossed over Orlando, the maximum sustained winds decreased to around 75 kt. When Hurricane Charley finally moved off the northeast coast of Florida, the maximum sustained winds were 65-70 kt.
Once Charley left Florida on 0330 UTC 14 August and entered the Atlantic, it accelerated north-northeastward while re-strengthening slightly. At about 1400 UTC 14 August, Charley made landfall near Cape Romain, South Carolina. From that point on, Charley continued to weaken as it passed through North Carolina, Virginia, and Massachusetts, where it became insignificant just after 1200 UTC 15 August.
Public Advisory for August 13, 2004 at 11pm
Both graphics taken from the National Hurricane Website
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