Hurricane Opal

Hurricane Opal was a large and powerful Category 4 hurricane that caused severe and extensive damage along the northern Gulf Coast of the United States in October 1995. The fifteenth named storm, ninth hurricane and strongest tropical cyclone of the unusually active 1995 Atlantic hurricane season, Opal developed from the interaction of a tropical wave and a low-pressure area near the Yucatán Peninsula on September 27 as Tropical Depression Seventeen. The depression crossed the Yucatán Peninsula and intensified into a tropical storm on September 30. Opal intensified into a hurricane on October 2 after entering the Gulf of Mexico. The cyclone turned northeastward and strengthened significantly. By October 4, Opal was an intense 150 mph (240 km/h), Category 4 hurricane. With a minimum pressure of 916 mbar (hPa), Hurricane Opal was the most intense category 4 Atlantic hurricane on record. However, the cyclone abruptly weakened to a low-end Category 3 hurricane prior to making landfall on the Florida Panhandle near Pensacola later that day. The storm quickly unraveled as it moved inland and became extratropical on October 5. The remnants of Opal moved northward and dissipated over Ontario the following day.

The precursor and initial stages of Opal brought heavy rainfall and flooding to Guatemala and Mexico. In the former, flooding and landslides left about 34,000 people homeless and damage to infrastructure and agriculture. A total of 31 deaths occurred in Guatemala. In Mexico, a number of rivers overflowed in the states of Campeche and Tabasco, forcing more than 42,000 people to evacuate. The storm left hundreds of millions of dollars in damage to agriculture in Campeche alone. Nineteen people were killed in the country. In Florida, high winds and storm surge left extensive damage in the panhandle. The majority of structures were swept away or experienced some degree of damage, particularly from Wakulla County westward. In Escambia, Okaloosa,Santa Rosa and Bay County, FL counties, nearly 300 homes were destroyed and 1,000 others suffered major damage. The storm left at least $2.1 billion in damage in Florida alone. Several other states were impacted by the storm, especially Alabama, where the storm spawned many tornadoes and strong winds downed numerous trees and left about 2.6 million people without electricity. A total of 27 deaths were attributed to Opal in the United States. The hurricane overall left about $4.7 billion in damage, much of which took place in the US. Due to its destructive effects, the name ''Opal'' was retired in the spring of 1996 and replaced with ''Olga'' for the 2001 season.

Meteorological history

The origins of Hurricane Opal were linked using satellite imagery and synoptic analyses to a tropical wave that left the western coast of Africa on September 11. Ten days later, the disturbance reached the Lesser Antilles after crossing the tropical Atlantic. Continuing westward, the disturbance showed little signs of organization before entering the western Caribbean Sea on September 23. There, the wave became entangled with a broad area of low-pressure east of Nicaragua, and the combined system drifted west-northwestward toward the Yucatán Peninsula; but even then, the disturbance lacked significant development. However, a burst of thunderstorm activity occurred near the storm's center on September 27, prompting the National Hurricane Center (NHC) to declare the system a tropical depression at 18:00  UTC that day. At the time, the depression was centered 80 mi (130 km) south-southeast of Cozumel, Mexico.

The primordial depression meandered across the Yucatán Peninsula during the three days following tropical cyclogenesis due to the lack of dominant steering currents. Despite remaining over land for an extended period, the depression developed organized rainbands, and ships in the region reported weather conditions that were suggestive of a stronger system. As a result, the NHC upgraded the disturbance to tropical storm intensity at 12:00 UTC on September 30 while the storm was over the north-central coast of Yucatán; this classification resulted in the tropical cyclone being named ''Opal'', which also made it the first Atlantic storm to be given a name starting with the letter O. Over the next two days, Opal entered the Gulf of Mexico before tracking slowly west-southwestward into the Bay of Campeche. There, the storm strengthened into a hurricane at 12:00 UTC on October 2. Shortly afterward, a primitive eye began to form. At the same time, a strong trough tracking across the United States caused Opal to slowly turn northeastward.

After clearing the Bay of Campeche, Opal accelerated towards the United States Gulf Coast. The combination of warm sea surface temperatures associated with an unusually warm pocket of ocean waters and an upper-level high pressure area over the Gulf of Mexico resulted in a highly conducive environment for intensification. After a significant reorganization in Opal's internal structure, the hurricane was able to rapidly intensify in these favorable conditions. At 12:00 UTC on October 4, Opal reached peak intensity with maximum sustained winds of 150 mph (240 km/h), making it a Category 4 hurricane on the Saffir–Simpson hurricane wind scale, and a minimum barometric pressure of 916 hPa (27.05 inHg), a pressure typical for a Category 5 hurricane. The tropical cyclone's eye measured 12 mi (19 km) at peak intensity as the storm was beginning an eyewall replacement cycle. The progression of this cycle resulted in Opal's gradual weakening thereafter. At 22:00 UTC that day, Opal made landfall between Pensacola Beach, Florida and Navarre Beach, Florida, on a stretch of beach now known as "Opal Beach", as a weakened Category 3 hurricane with winds of 115 mph (185 km/h). Weakening quickened as Opal moved further inland, degenerating into a tropical depression over Tennessee less than a day after landfall. The diffusing cyclone transitioned into an extratropical cyclone shortly afterwards; these extratropical remnants tracked towards the northeast before they were last noted along the northern shore of Lake Ontario in Eastern Ontario.

Preparations

Although Opal was a weak system located over the Yucatán Peninsula at the time, 350 people evacuated from Grand Isle, Louisiana on September 28 after rough surf associated with the distant cyclone began to threaten Louisiana Highway 1—the only thoroughfare connecting Grand Isle with the Louisianan mainland. The following day, oil companies operating offshore oil drilling platforms in the Gulf of Mexico began evacuating workers from the rigs to land. On October 1, a coastal flood watch was issued for portions of the United States Coast due to the risk of storm surge from Opal. The United States Coast Guard issued an advisory for boaters in the Gulf of Mexico to use caution or remain in port where possible. The next day, the Galveston, Texas, emergency operations center opened to monitor the tropical cyclone and deliberate upon potential preparations for the city. Meanwhile, the launch Space Shuttle Columbia's STS-73 mission set for October 5 was postponed due to Opal's anticipated effects.

On October 3, a voluntary evacuation order was placed on Plaquemines Parish, Louisiana, due to the risks of potential storm surge. Schools were also closed by noon that day across the parish. Voluntary evacuation orders for the Florida panhandle, which would ultimately be the most heavily affected area, also began the same day with several counties giving evacuation orders. Farther west, a mandatory evacuation order was placed on Mobile County, Alabama, by then-Governor Fob James. Just before noon on October 4, with the hurricane near landfall, Escambia, Okaloosa and Santa Rosa counties halted evacuations, instead ordering those still within vulnerable areas to seek shelter instead. However, the large number of evacuees led to severe traffic congestion; Escambia County officials estimated that "tens of thousands" were still on evacuation routes within the county only a few hours before Opal made landfall. Mass evacuations in some other counties concluded during the afternoon of October 4, though many evacuees in other locations were unable to reach safe areas prior to the onset of gale-force winds.

An estimated 100,000 people evacuated from the United States Gulf Coast ahead of Opal, with 5 percent of evacuees seeking public shelters and over half of evacuees seeking shelter out of their home counties; in their post-storm assessment the Federal Emergency Management Agency (FEMA) noted that the landfalls of Hurricane Allison and Hurricane Erin on the Florida panhandle earlier in the year produced a dichotomous mood toward preparations for Hurricane Opal—some people may have taken a "wait and see" approach that resulted in complacency, while others affected by the widespread power outages caused by Erin may have acquired a greater sense of readiness toward the approaching hurricane. Regardless, the overall evacuation process was described as chaotic, and the failure to clear hurricane evacuation routes of casual or communal traffic was blamed for the relative unease during evacuations for Opal. Traffic congestion on these routes caused some evacuees to return to vulnerable areas along the coast while raising fears that stranded evacuees on highways could be subjected to potentially fatal hurricane-force winds.

The post-landfall watches and warnings released in accordance with Opal were a flash flood warning released on October 5 for portions of Alabama, northern Georgia, and the western parts of North Carolina and South Carolina. The warning also included eastern Tennessee. A flash flood watch was also in effect for portions of the Upper Ohio Valley, the Mid-Atlantic region, the central Appalachians, and the lower Great Lakes. Wind warnings were in effect for northwestern South Carolina all the way to western New York. A gale watch was also in effect for Lake Erie, Lake Ontario, and the southern sections of the St. Lawrence Seaway.

Six hours later, the gale warnings over Lake Erie, Lake Ontario, and the southern sections of the St. Lawrence Seaway were upgraded into a storm warning for Erie alone. The gale warning for the other two sections remained. The shoreline of Lake Erie was under a beach erosion warning from Buffalo, New York to Ripley, New York. The Storm Prediction Center released a tornado watch for northern and central New Jersey and portions of New York and Connecticut on October 6.

Significant non-surge areas of Escambia County, Florida, south of US 98 were included in evacuation areas because of the potential for isolation by flooding.

Impact

Mexico and Central America

Although Opal was only a weak tropical storm when it affected the Yucatán Peninsula, its slow movement led to prolonged, flooding rains over much of the region. Tabasco received about 20 percent of its annual rainfall in four days due to the cyclone. Across Campeche and Tabasco, more than 42,000 people were forced to evacuate as rivers overflowed their banks. According to Notimex, approximately 100,000 people evacuated due to the storm. By October 1, an estimated 500,000 acres of crops had been destroyed by the floods. (Accessed through LexisNexis) In San Francisco de Campeche, flood waters reached a depth of . Governor Jorge Salomon ordered the closure of all government offices, businesses, and schools by October 2 in light of the extensive flooding. At least 60 towns across the state were isolated by the extreme rainfall. By October 3, agricultural losses in Campeche alone were estimated in the billions of pesos (hundreds of millions of USD). At least 19 people perished across Mexico while another 31 were killed in Guatemala.

Florida

About of Florida's coastline felt the impact of Hurricane Opal. Geocities Article on Hurricane Opal
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Rainfall in Florida peaked at in Ellyson, at Pensacola, and at Hurlburt Field. The highest gust recorded was a gust at the latter. Lower gusts were at Eglin Air Force Base and an gust at Pensacola P.N.S. The highest sustained winds were at Hurlburt Field and at Eglin Air Force Base. Opal brought heavy surge to the area, to in some places, comparing itself to Hurricane Eloise, which struck the same area at near equal strength in 1975.The two reported storm surges were to above normal at Apalachicola and to above normal at Sarasota.

Opal caused about US$4.7 billion (1995 dollars) in damage, making it the third costliest hurricane at the time. Most of the structural damage occurred near the coastline on the Florida Panhandle, due to intense surge. Nearly a mile of U.S. Highway 98 near Eglin Air Force Base was completely destroyed. The pavement was nearly replaced by mounds of sand left behind after storm surge. Opal also spawned an F2 tornado that killed a young woman in Florida. None died as a direct result of storm surge. This was quite unusual, considering the strength and landfall location of Opal. Okaloosa Island, Fort Walton Beach, was overwhelmed by storm surge. Numerous homes were under to of water. Residents were not allowed to return to the island until the homes could be secured. A Humvee tour was arranged by the National Guard so home owners could 'see' the damage, but the homeowners were not allowed off the bus. Sand dunes along the stretch of US 98, normally high, were removed by wind and surge. Where once the ocean was obscured from view by the dunes for miles, a flat open space opened up along U.S. Highway 98.

U.S. Gulf Coast

The peak rainfall from Opal in Alabama was east-northeast of Brewton, Alabama. Lesser amounts include in Mobile and in Anniston. The highest gust reported was a gust in Fort Rucker and a secondary one at Maxwell Air Force Base with a gust of . The highest sustained winds reported from Opal was at Fort Rucker, in downtown Mobile and at Maxwell Air Force Base and Montgomery. Numerous downed trees across much of the southeastern United States left over 2 million people without power. Alabama reported that 476,000 residents were without power, which was a record at the time; however, this number was surpassed by Hurricane Ivan in 2004. Damage was heavy far inland, all the way to Montgomery, where sustained winds reached .

Highest rainfalls in Mississippi were throughout the eastern side of the state with lower amounts going westward. Tropical-storm-force winds were reported along the Gulf Coast during the afternoon and early evening of October 4. Wind damage was mainly limited to downed tree limbs, power lines, and signs. One minor injury was reported in Harrison County due to flying debris. Damage in Mississippi totaled up to $75 thousand.

In Louisiana, the only significant wind damage occurred in extreme south Plaquemines Parish where winds were estimated around with gusts to hurricane force, with wind damage reported to some mobile homes and roofs of a few other structures. Tropical storm force winds were reported in extreme south Lafourche Parish and Jefferson Parish, as well as extreme east St. Bernard Parish. Property damage cost estimated. Tides were generally above normal in Lake Pontchartrain, and three to five feet above normal along the southeast Louisiana coast from Grand Isle eastward. Some low-lying coastal roads were flooded. Approximately 10,000 people evacuated from the southern, or lower, portions of Plaquemines, St. Bernard, Lafourche, and Jefferson Parishes. The only significant gathering of persons in public shelters occurred in Plaquemines Parish, where 1,600 people were placed in public shelters. Although no direct injuries occurred from the hurricane, an indirect injury is attributed to the hurricane in a freak accident. A Jefferson Parish employee was injured while attempting to lower a large flag on October 4. The employee, who was holding onto a rope attached a flag, was tossed high into the air, and suffered severe injuries when he fell back to the ground. Total damage in Louisiana totaled out to US$200,000 (1995 dollars).

Breaking swells from Opal in Texas caused water to spill across at the usual wash-over points which damaged several vehicles.

Southeastern United States

The peak rainfall in Georgia was in Marietta, in Peachtree City, and 7.17 in (182 mm) in west Atlanta. Southern Georgia only reported of rain, while the northern part of the state reached about . The peak wind gust in Georgia was a 79 mph (127 km/h) gust in Marietta, a 70 mph (113 km/h) gust in Columbus, and a 56 mph (90 km/h) gust in the Atlanta-Hartsfield area. High winds in Rabun County caused $5 million (1995 USD) from the approach of Opal on October 5. The damage was worst in Rabun County where numerous trees were blown down. The wind damage was described as being worse than the March Superstorm of 1993. Power was out for some people for at least a week. More than 4000 trees were knocked down within the city of Atlanta alone. These trees fell across roads, and on power lines, homes, mobile homes, and automobiles. More than a half a dozen people were injured from falling trees in the early morning hours of October 5. There were more than 1200 telephone poles knocked down and almost 5,000 power lines snapped. Power crews from surrounding states helped to restore power to many, however, thousands of residences remained without power through the weekend.

An 80-foot (24 m) gash was torn out of Interstate 285 between Roswell Road and the Glenridge Connector in Atlanta. Schools were closed on October 5 and October 6 throughout the cities of Atlanta, Marietta, and in Fulton, Coweta, Carroll and Douglas counties. A total of 47 of 101 schools were closed in Dekalb County alone. Four state parks were closed after Opal: Moccasin Creek Park, Black Rock Mountain, Vogel State Park, and Fort Mountain State Park

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