The 1962 Atlantic hurricane season featured Hurricanes Daisy and Ella – two tropical cyclones that showed the latest dates for the fourth and fifth named storms on record since tropical cyclones were first named in the North Atlantic ocean, starting in 1950, when they both formed on September 29 and October 14. On the same hand, it was the least active since 1939, with only five named storms. Although the season officially began on June 15, the first named storm did not form until August 26, the third-latest date. Hurricane Alma brushed the Outer Banks before becoming extratropical southeast of New England, destroying hundreds of boats and producing beneficial rainfall. In late August, Tropical Storm Becky developed unusually far east in the Atlantic Ocean, becoming the easternmost storm on record to recurve to the northeast. Celia followed in the September, forming east of the Lesser Antilles and executing a loop near Bermuda before dissipating. Hurricane Daisy, the latest fourth named storm, was the costliest of the season, leaving about $1.1 million in damage in New England (1962 USD). The storm dropped the highest rainfall total on record in Maine, and its precipitation caused 22 traffic fatalities. The final hurricane – Ella – the latest fifth named storm – was also the strongest, remaining offshore of the eastern United States but causing two deaths.
The 1971 Atlantic hurricane season was an active Atlantic hurricane season overall, producing 13 named storms, of which 6 strengthened into hurricanes. The season officially began on June 1, 1971, and lasted until November 30, 1971. These dates conventionally delimit the period of each year when most tropical cyclones form in the Atlantic basin. This season, the first storm, Arlene, developed on July 4, while the last, Laura, dissipated on November 22.
The 1973 Atlantic hurricane season was a below average tropical cyclone season overall. Of the 24 tropical or subtropical cyclones which developed, only 8 became named storms, and of those, only 4 became hurricanes, with 1 reaching major hurricane status on the newly implemented Saffir–Simpson hurricane wind scale. This continued the pattern of storm activity from the previous season, as hostile El Niño–Southern Oscillation (ENSO) conditions again hindered tropical cyclogenesis and intensification in the tropical Atlantic Ocean and Caribbean Sea.
The 1981 Atlantic hurricane season featured direct or indirect impacts from nearly all of its 12 tropical or subtropical storms. Overall, the season was fairly active, with 22 tropical depressions, 12 of which became a namable storm, while 7 of those reached hurricane status and 3 intensified into major hurricanes. The season officially began on June 1, 1981, and lasted until November 30, 1981. These dates conventionally delimit the period of each year when most tropical cyclones form in the Atlantic basin. However, tropical cyclogenesis can occur before these dates, as demonstrated with the development of two tropical depressions in April and Tropical Storm Arlene in May. At least one tropical cyclone formed in each month between April and November, with the final system, Subtropical Storm Three, becoming extratropical on November 17, 1981.
The 1982 Atlantic hurricane season was an extremely inactive Atlantic hurricane season with five named tropical storms and one subtropical storm. Two storms became hurricanes, one of which reached major hurricane status. The season officially began on June 1, 1982, and lasted until November 30, 1982. These dates conventionally delimit the period of each year when most tropical cyclones form in the Atlantic basin. Activity started early with Hurricane Alberto forming on the first day of the season. Alberto threatened the Southwestern Florida coast as a tropical storm, meadering offshore in the southeastern Gulf of Mexico and causing 23 fatalities in Cuba. The next system, a subtropical storm, formed later in June and affected the same area as Alberto, causing $10 million in damage.
The 1984 Atlantic hurricane season was the most active since 1971, though the season was below average in hurricanes and major hurricanes. It officially began on June 1, 1984, and lasted until November 30, 1984. These dates conventionally delimit the period of each year when most tropical cyclones form in the Atlantic basin. The 1984 season was an active one in terms of named storms, but most of them were weak and stayed at sea. Most of the cyclones tracked through the northwest subtropical Atlantic west of the 50th meridian to near the Eastern coast of the United States between mid-August and early October. The most damaging storm was Hurricane Klaus, which caused $152 million (1984 dollars) in damage in Puerto Rico. Hurricane Diana was the first hurricane to strike a nuclear power plant without incident; it was also the first major hurricane to strike the U.S. East Coast in nearly 20 years. Also of note was Hurricane Lili, which lasted well after the official end of the season. It was downgraded from a named storm on December 24. Damage overall from the tropical cyclones in 1984 totaled $228.7 million. Unusually, no hurricanes developed from tropical waves in 1984, which usually are the source of the strongest storms in an Atlantic hurricane season.
The 1998 Pacific hurricane season was a fairly average Pacific hurricane season. Despite this, it had nine hurricanes and six major hurricanes, which was well above average. The season officially started on May 15 in the eastern Pacific and on June 1 in the central Pacific, and ended on November 30; these dates conventionally delimit the period during which most tropical cyclones form in that region. The first tropical cyclone developed on June 11, about ten days later than the normal start of the season. The final storm of the year, Hurricane Madeline, dissipated on October 20. Storm activity in the Central Pacific Hurricane Center's warning zone was low, with just one tropical depression observed in the region. Two tropical cyclones from the eastern Pacific also entered the central Pacific; the former did so as a hurricane.
The 1996 Pacific hurricane season had below normal tropical cyclone activity, producing 9 tropical storms, of which 5 became hurricanes, with 2 of those intensifying into major hurricanes. With an Accumulated cyclone energy (ACE) index of 53.9, the season ranks among the least intense Pacific hurricane seasons on record. It officially began May 15, 1996, in the eastern north Pacific and on June 1, 1996, in the central north Pacific. It ended on November 30, 1996. These dates conventionally delimit the period of each year when most tropical cyclones form in the northeastern Pacific Ocean. The season slightly exceeded these bounds when tropical storm One-E formed on May 13.
The 1986 Pacific hurricane season featured several tropical cyclones that contributed to significant flooding to the Central United States. The hurricane season officially started May 15, 1986, in the eastern Pacific, and June 1, 1986 in the central Pacific, and lasted until November 30, 1986 in both regions. These dates conventionally delimit the period of each year when most tropical cyclones form in the northeastern Pacific Ocean. A total of 17 named storms and 9 hurricanes developed during the season; this is slightly above the averages of 15 named storms and 8 hurricanes, respectively. In addition, 26 tropical depressions formed in the eastern Pacific during 1986, which, at the time, was the second most ever recorded; only the 1982 Pacific hurricane season saw a higher total.
A tropical cyclone rainfall climatology is developed to determine rainfall characteristics of past tropical cyclones. A tropical cyclone rainfall climatology can be used to help forecast current or upcoming tropical cyclone impacts. The degree of a tropical cyclone rainfall impact depends upon speed of movement, storm size, and degree of vertical wind shear. One of the most significant threats from tropical cyclones is heavy rainfall. Large, slow moving, and non-sheared tropical cyclones produce the heaviest rains. The intensity of a tropical cyclone appears to have little bearing on its potential for rainfall over land, but satellite measurements over the last several years show that more intense tropical cyclones produce noticeably more rainfall over water. Flooding from tropical cyclones remains a significant cause of fatalities, particularly in low-lying areas.
Tropical Storm Frances caused extensive flooding in Mexico and Texas in September 1998. The sixth tropical cyclone and sixth named storm of the annual hurricane season, Frances developed from a low pressure area in the Gulf of Mexico on September 8. The cyclone moved northward through the western Gulf of Mexico, making landfall across the central Texas coastline before recurving across the Midwest through southeast Canada and New England. A large tropical cyclone for the Atlantic basin, yet an average sized system by western Pacific standards, the storm produced heavy rains across the Isthmus of Tehuantepec, Texas, western Louisiana and the Great Plains.
Tropical cyclone rainfall forecasting involves using scientific models and other tools to predict the precipitation expected in tropical cyclones such as hurricanes and typhoons. Knowledge of tropical cyclone rainfall climatology is helpful in the determination of a tropical cyclone rainfall forecast. More rainfall falls in advance of the center of the cyclone than in its wake. The heaviest rainfall falls within its central dense overcast and eyewall. Slow moving tropical cyclones, like Hurricane Danny and Hurricane Wilma, can lead to the highest rainfall amounts due to prolonged heavy rains over a specific location. However, vertical wind shear leads to decreased rainfall amounts, as rainfall is favored downshear and slightly left of the center and the upshear side is left devoid of rainfall. The presence of hills or mountains near the coast, as is the case across much of Mexico, Haiti, the Dominican Republic, much of Central America, Madagascar, Réunion, China, and Japan act to magnify amounts on their windward side due to forced ascent causing heavy rainfall in the mountains. A strong system moving through the mid latitudes, such as a cold front, can lead to high amounts from tropical systems, occurring well in advance of its center. Movement of a tropical cyclone over cool water will also limit its rainfall potential. A combination of factors can lead to exceptionally high rainfall amounts, as was seen during Hurricane Mitch in Central America.
The United States tropical cyclone rainfall climatology concerns the amount of precipitation, primarily in the form of rain, which occurs during tropical cyclones and their extratropical cyclone remnants across the United States. Typically, five tropical cyclones and their remnants impact the country each year, contributing between a tenth and a quarter of the annual rainfall across the southern tier of the country. The highest rainfall amounts appear close to the coast, with lesser amounts falling farther inland. Obstructions to the precipitation pattern, such as the Appalachian mountains, focus higher amounts from northern Georgia through New England. While most impacts occur with systems moving in from the Atlantic Ocean or Gulf of Mexico, some emanate from the eastern Pacific Ocean, with a few crossing Mexico before impacting the Southwest. Those making landfall within the Southeast portion of the country tend to have the greatest potential for heavy rains.
The radius of maximum wind (RMW) is the distance between the center of a cyclone and its band of strongest winds. It is a parameter in atmospheric dynamics and tropical cyclone forecasting. The highest rainfall rates occur near the RMW of tropical cyclones. The extent of a cyclone's storm surge and its maximum potential intensity can be determined using the RMW. As maximum sustained winds increase, the RMW decreases. Recently, RMW has been used in descriptions of tornadoes. When designing buildings to prevent against failure from atmospheric pressure change, RMW can be used in the calculations.
Tropical cyclone track forecasting involves predicting where a tropical cyclone is going to track over the next five days, every 6 to 12 hours. The history of tropical cyclone track forecasting has evolved from a single-station approach to a comprehensive approach which uses a variety of meteorological tools and methods to make predictions. The weather of a particular location can show signs of the approaching tropical cyclone, such as increasing swell, increasing cloudiness, falling barometric pressure, increasing tides, squalls and heavy rainfall.
The following is a glossary of tropical cyclone terms.
