Tropical cyclone seasonal forecasting is the process of predicting the number of tropical cyclones in one of the world's seven tropical cyclone basins during a particular tropical cyclone season. In the north Atlantic Ocean, one of the most widely publicized annual predictions comes from the Tropical Meteorology Project at Colorado State University. These reports are written by Philip J. Klotzbach and William M. Gray.
Since 1984, Dr William M. Gray and his associates at the Colorado State University have issued a seasonal forecast, that has aimed to predict the number of tropical storms and hurricanes that will develop within the Atlantic basin during the upcoming season amongst other factors. The forecasts were initially issued ahead of time for June and August. [1]
After the active 2005 Atlantic hurricane season, Dr Gray decided to allow Philip J. Klotzbach to take the primary responsibility for the project's seasonal, monthly and landfall probability forecasts effective with the first forecast for the 2006 Atlantic hurricane season. [2]
Ahead of each season several national meteorological services issue forecasts of how many tropical cyclones will form during a season and/or how many tropical cyclones will affect a particular country. Examples include the United Kingdom's Met Office which issues a "seasonal forecast". in May/June of the number of tropical storms for the upcoming Atlantic hurricane season, while the Philippine Atmospheric, Geophysical and Astronomical Service tries to predict how many tropical cyclones will move into its area of responsibility.
In August 1998, the United States Climate Prediction Center in conjunction with the National Hurricane Center and the Hurricane Research Division issued a tropical cyclone outlook, which accurately predicted that there would be an above-normal number of tropical storms and hurricanes in the Atlantic between August and October. [3] The NOAA centres subsequently started to issue an outlook that gave a general guide to the expected overall activity within the Atlantic Ocean.
Ahead of the 2003 Pacific hurricane season, the NOAA forecasters decided to start issuing an experimental tropical cyclone outlook for the Eastern Pacific, which was designed not to be updated during the mid-season. [4] As a result of both the 2003 and 2004 outlooks being successful, the predictions became an operational product during 2005. [5]
NOAA is also one of the contributors to New Zealand's National Institute of Water & Atmospheric Research Tropical Cyclone Outlook, through its National Weather Service forecast offices in the region and the Climate Prediction Center. [6]
New Zealand's National Institute of Water & Atmospheric Research (NIWA) and collaborating agencies including the Meteorological Service of New Zealand and Pacific Island National Meteorological Services issue the "Island Climate Update Tropical Cyclone Outlook" for the Pacific. This forecast attempts to predict how many tropical cyclones and severe tropical cyclones will develop within the Southern Pacific between 135°E and 120°W as well as how many will affect a particular island nation. The Fiji Meteorological Service while collaborating with NIWA and partners also publishes its own seasonal forecast but for the South Pacific basin between 160°E and 120°W. Since the start of the 2009–10 season, the Australian Bureau of Meteorology's National Climate Center has publicly released a forecast for the Australian region which focused on the broadscale aspects of the cyclone season, and forecasted how likely it was that a subregion was to see activity above the average as well as how many tropical cyclones may occur within the basin and each of its subregions. [7] [8] However ahead of the 2011–12 season the NCC stopped forecasting publicly how many tropical cyclones may occur in a certain region and just forecasted how likely it was that a subregion was to see activity above the average. [9]
The National Hurricane Center (NHC) is the division of the United States' NOAA/National Weather Service responsible for tracking and predicting tropical weather systems between the Prime Meridian and the 140th meridian west poleward to the 30th parallel north in the northeast Pacific Ocean and the 31st parallel north in the northern Atlantic Ocean. The agency, which is co-located with the Miami branch of the National Weather Service, is situated on the campus of Florida International University in Westchester, Florida.
The Weather Prediction Center (WPC), located in College Park, Maryland, is one of nine service centers under the umbrella of the National Centers for Environmental Prediction (NCEP), a part of the National Weather Service (NWS), which in turn is part of the National Oceanic and Atmospheric Administration (NOAA) of the U.S. Government. Until March 5, 2013 the Weather Prediction Center was known as the Hydrometeorological Prediction Center (HPC). The Weather Prediction Center serves as a center for quantitative precipitation forecasting, medium range forecasting, and the interpretation of numerical weather prediction computer models.
Accumulated cyclone energy (ACE) is a metric used by various agencies to express the energy released by a tropical cyclone during its lifetime. It is calculating by summing the square of a tropical cyclone's maximum sustained winds, measured every six hours. The resulting total can be divided by 10,000 to make it more manageable, or added to other totals in order to work out a total for a particular group of storms.
William "Bill" Mason Gray was emeritus professor of atmospheric science at Colorado State University (CSU), and the head of the Tropical Meteorology Project at CSU's Department of Atmospheric Sciences. He is widely regarded as a pioneer in the science of tropical cyclone forecasting and one of the world's leading experts on tropical storms. After retiring as a faculty member at CSU in 2005, Gray remained actively involved in both climate change and tropical cyclone research until his death.
The 2006 Atlantic hurricane season was the least active since 1997 as well as the first season since 2001 in which no hurricanes made landfall in the United States, and was the first since 1994 in which no tropical cyclones formed during October. Following the intense activity of 2003, 2004, and 2005, forecasters predicted that the 2006 season would be only slightly less active. Instead activity was slowed by a rapidly forming moderate El Niño event, the presence of the Saharan Air Layer over the tropical Atlantic, and the steady presence of a robust secondary high-pressure area to the Azores High centered on Bermuda. There were no tropical cyclones after October 2.
The Atlantic hurricaneseason is the period in a year from June through November when tropical cyclones form in the Atlantic Ocean, referred to in North American countries as hurricanes, tropical storms, or tropical depressions. In addition, there have been several storms over the years that have not been fully tropical and are categorized as subtropical depressions and subtropical storms. Even though subtropical storms and subtropical depressions are not technically as strong as tropical cyclones, the damages can still be devastating.
Tropical cyclogenesis is the development and strengthening of a tropical cyclone in the atmosphere. The mechanisms through which tropical cyclogenesis occurs are distinctly different from those through which temperate cyclogenesis occurs. Tropical cyclogenesis involves the development of a warm-core cyclone, due to significant convection in a favorable atmospheric environment.
A Regional Specialized Meteorological Centre (RSMC) is responsible for the distribution of information, advisories, and warnings regarding the specific program they have a part of, agreed by consensus at the World Meteorological Organization as part of the World Weather Watch.
Traditionally, areas of tropical cyclone formation are divided into seven basins. These include the north Atlantic Ocean, the eastern and western parts of the northern Pacific Ocean, the southwestern Pacific, the southwestern and southeastern Indian Oceans, and the northern Indian Ocean. The western Pacific is the most active and the north Indian the least active. An average of 86 tropical cyclones of tropical storm intensity form annually worldwide, with 47 reaching hurricane/typhoon strength, and 20 becoming intense tropical cyclones, super typhoons, or major hurricanes.
Tropical cyclone forecasting is the science of forecasting where a tropical cyclone's center, and its effects, are expected to be at some point in the future. There are several elements to tropical cyclone forecasting: track forecasting, intensity forecasting, rainfall forecasting, storm surge, tornado, and seasonal forecasting. While skill is increasing in regard to track forecasting, intensity forecasting skill remains unchanged over the past several years. Seasonal forecasting began in the 1980s in the Atlantic basin and has spread into other basins in the years since.
The 2009 Atlantic hurricane season was a below-average Atlantic hurricane season that produced eleven tropical cyclones, nine named storms, three hurricanes, and two major hurricanes. It officially began on June 1 and ended on November 30, dates that conventionally delimit the period of each year when most tropical cyclones develop in the Atlantic basin. The season's first tropical cyclone, Tropical Depression One, developed on May 28, while the final storm, Hurricane Ida, dissipated on November 10. The most intense hurricane, Bill, was a powerful Cape Verde-type hurricane that affected areas from the Leeward Islands to Newfoundland. The season featured the lowest number of tropical cyclones since the 1997 season, and only one system, Claudette, made landfall in the United States. Forming from the interaction of a tropical wave and an upper-level low, Claudette made landfall on the Florida Panhandle with maximum sustained winds of 45 mph (70 km/h) before quickly dissipating over Alabama. The storm killed two people and caused $228,000 in damage.
The 2012–13 Australian region cyclone season was a slightly below average tropical cyclone season event in the ongoing cycle of tropical cyclone formation. It officially started on 1 November 2012, and officially ended on 30 April 2013, despite Cyclone Zane being an active system at the time. The regional tropical cyclone operational plan defines a "tropical cyclone year" separately from a "tropical cyclone season"; the "tropical cyclone year" began on 1 July 2012 and ended on 30 June 2013.
The 2012 Atlantic hurricane season was the final year in a consecutive string of three very active seasons since 2010, with 19 tropical storms; although many of the storms were weak and short-lived. The 2012 season was also a costly season in terms of property damage, and remains the fourth-costliest season, behind 2021, 2005 and 2017. The season officially began on June 1 and ended on November 30, dates that conventionally delimit the period during each year in which most tropical cyclones form in the Atlantic Ocean. However, Alberto, the first named system of the year, developed on May 19 – the earliest date of formation since Subtropical Storm Andrea in 2007. A second tropical cyclone, Beryl, developed later that month. This was the first occurrence of two pre-season named storms in the Atlantic basin since 1951. It moved ashore in North Florida on May 29 with winds of 65 mph (105 km/h), making it the strongest pre-season storm to make landfall in the Atlantic basin. This season marked the first time since 2009 where no tropical cyclones formed in July. Another record was set by Hurricane Nadine later in the season; the system became the fourth-longest-lived tropical cyclone ever recorded in the Atlantic, with a total duration of 22.25 days. The final storm to form, Tony, dissipated on October 25 – however, Hurricane Sandy, which formed before Tony, became extratropical on October 29.
The 2015 Atlantic hurricane season was the last of three consecutive below average Atlantic hurricane seasons. It produced twelve tropical cyclones, eleven named storms, four hurricanes, and two major hurricanes. The Accumulated Cyclone Energy (ACE) for the season was 68% of the long-term median value. The hurricane season officially began on June 1, 2015, and ended on November 30, 2015. These dates historically describe the period each year when most tropical cyclones form in the North Atlantic basin. However, the first named storm, Ana, developed on May 8, nearly a month before the official start of the season, the first pre-season cyclone since Beryl in 2012 and the earliest since Ana in 2003. The formation of Ana marked the start of a series of seven consecutive seasons with pre-season activity, spanning from 2015 to 2021. The season concluded with Kate transitioning into an extratropical cyclone on November 11, almost three weeks before the official end.
The 2013 Atlantic hurricane season was a well below average Atlantic hurricane season and the first since 1994 with no major hurricanes. It was well below average for both hurricanes and major hurricanes but it was a slightly above average year for named storms. It was also the first season in the satellite era with no storms of at least Category 2 intensity on the Saffir–Simpson hurricane wind scale. The first tropical cyclone of the season, Andrea, developed on June 5, while the final cyclone, an unnamed subtropical storm, dissipated on December 7. Throughout the year, only two storms—Humberto and Ingrid—reached hurricane intensity; this was the lowest seasonal total since 1982.
The 2014 Atlantic hurricane season was a below-average hurricane season in terms of named storms and major hurricanes, though average in terms of number of hurricanes overall. It produced nine tropical cyclones, eight of which became named storms; six storms became hurricanes and two intensified further into major hurricanes. The season officially began on June 1, and ended on November 30. These dates historically describe the period each year when most tropical cyclones form in the Atlantic basin. The first storm of the season, Arthur, developed on July 1, while the final storm, Hanna, dissipated on October 28, about a month prior to the end of the season. 2014 is the most recent year with an average or below average number of named Atlantic storms.
The Tuvalu Meteorological Service (TMS) is the principal meteorological observatory of Tuvalu and is responsible for providing weather services to the islands of Tuvalu. A meteorological office was established on Funafuti at the time the islands of Tuvalu were administered as parts of the Gilbert and Ellice Islands colony of the United Kingdom. The meteorological office is now an agency of the government of Tuvalu.
The 2014–2016 El Niño was a warming of the eastern equatorial Pacific Ocean that resulted in unusually warm waters developing between the coast of South America and the International Date Line. These unusually warm waters influenced the world's weather in a number of ways, which in turn significantly affected various parts of the world. These included drought conditions in Venezuela, Australia and a number of Pacific islands while significant flooding was also recorded. During the event, more tropical cyclones than normal occurred within the Pacific Ocean, while fewer than normal occurred in the Atlantic Ocean.
The 2021 Atlantic hurricane season was the third-most active Atlantic hurricane season on record, producing 21 named storms and becoming the second season in a row – and third overall – in which the designated 21-name list of storm names was exhausted. Consequently, the season also became the sixth consecutive year with above-average tropical cyclone activity in terms of the number of named storms. Seven of those storms strengthened into a hurricane, four of which reached major hurricane intensity, which is just slightly above-average. The season officially began on June 1 and ended on November 30. These dates historically describe the period in each year when most Atlantic tropical cyclones form. However, subtropical or tropical cyclogenesis is possible at any time of the year, as demonstrated by Tropical Storm Ana's development on May 22, making this the seventh consecutive year in which a storm developed outside of the official season. That streak ended with the 2021 season, as there were no pre-season cyclones in 2022.
The 2022 Atlantic hurricane season is the current cycle of the annual tropical cyclone season in the Atlantic Ocean in the Northern Hemisphere. The season officially began on June 1, and will end on November 30. These dates, adopted by convention, historically describe the period in each year when most subtropical or tropical cyclogenesis occurs in the Atlantic Ocean. This year's first named storm, Tropical Storm Alex, developed five days after the start of the season, making this the first season since 2014 not to have a pre-season named storm. There have been eleven named tropical storms so far in the season. Five of them strengthened into a hurricane, and two reached major hurricane intensity.
