The westerlies, anti-trades, or prevailing westerlies, are prevailing winds from the west toward the east in the middle latitudes between 30 and 60 degrees latitude. They originate from the high-pressure areas in the horse latitudes and trend towards the poles and steer extratropical cyclones in this general manner. Tropical cyclones which cross the subtropical ridge axis into the westerlies recurve due to the increased westerly flow. The winds are predominantly from the southwest in the Northern Hemisphere and from the northwest in the Southern Hemisphere.
The 1940 Atlantic hurricane season was a generally average period of tropical cyclogenesis in 1940. Though the season had no official bounds, most tropical cyclone activity occurred during August and September. Throughout the year, fourteen tropical cyclones formed, of which nine reached tropical storm intensity; six were hurricanes. None of the hurricanes reached major hurricane intensity. Tropical cyclones that did not approach populated areas or shipping lanes, especially if they were relatively weak and of short duration, may have remained undetected. Because technologies such as satellite monitoring were not available until the 1960s, historical data on tropical cyclones from this period are often not reliable. As a result of a reanalysis project which analyzed the season in 2012, an additional hurricane was added to HURDAT. The year's first tropical storm formed on May 19 off the northern coast of Hispaniola. At the time, this was a rare occurrence, as only four other tropical disturbances were known to have formed prior during this period; since then, reanalysis of previous seasons has concluded that there were more than four tropical cyclones in May before 1940. The season's final system was a tropical disturbance situated in the Greater Antilles, which dissipated on November 8.
The 1939 Atlantic hurricane season was the least active since 1930. The season had below normal activity, with only six tropical storms, of which three became hurricanes and one became a major hurricane, equivalent to Category 3 status or higher on the modern-day Saffir–Simpson scale. The first tropical cyclone formed on June 12, and the last dissipated on November 6. These dates are within the period of each year when most tropical cyclones form in the Atlantic basin.
The 1929 Atlantic hurricane season was among the least active hurricane seasons in the Atlantic on record – featuring only five tropical cyclones. Of these five tropical systems, three of them intensified into a hurricane, with one strengthening further into a major hurricane. The first tropical cyclone of the season developed in the Gulf of Mexico on June 27. Becoming a hurricane on June 28, the storm struck Texas, bringing strong winds to a large area. Three fatalities were reported, while damage was conservatively estimated at $675,000 (1929 USD).
The 1912 Atlantic hurricane season featured the first recorded major hurricane – Category 3 or higher on the modern day Saffir–Simpson scale – in the month of November. There were eleven tropical cyclones, seven of which became tropical storms; four of those strengthened into hurricanes, and one reached major hurricane intensity. The season's first cyclone developed on April 4, while the final dissipated on November 21. The season's most intense and most devastating tropical cyclone was the final storm, known as the Jamaica hurricane. It produced heavy rainfall on Jamaica, leading to at least 100 fatalities and about $1.5 million (1912 USD) in damage. The storm was also blamed for five deaths in Cuba.
The 1900 Atlantic hurricane season featured the Galveston hurricane, the deadliest natural disaster in the history of the United States. A total of 10 tropical cyclones formed, seven of which intensified into a tropical storm. Three of those made landfall in the United States. The first system was initially observed over the central Atlantic Ocean on January 17, while the final storm transitioned into an extratropical cyclone on October 28. These dates fall within the period with the most tropical cyclone activity in the Atlantic. Every storm of the season except the seventh system existed simultaneously with another tropical cyclone.
The 2000 Pacific typhoon season marked the first year using names contributed by the World Meteorological Organization. It was a rather below-average season, producing a total of 23 tropical storms, 13 typhoons and 4 intense typhoons. The season ran throughout 2000, though typically most tropical cyclones develop between May and October. The season's first named storm, Damrey, developed on May 7, while the season's last named storm, Soulik, dissipated on January 4 of the next year.
The 1992 Pacific typhoon season had no official bounds; it ran year-round in 1992. Despite this, most tropical cyclones tend to form in the northwestern Pacific Ocean between May and November. These dates conventionally delimit the period of each year when most tropical cyclones form in the northwestern Pacific Ocean.
The 1971 Pacific typhoon season has no official bounds; it ran year-round in 1971, but most tropical cyclones tend to form in the northwestern Pacific Ocean between June and December. These dates conventionally delimit the period of each year when most tropical cyclones form in the northwestern Pacific Ocean.
The 1960 Pacific typhoon season had no official bounds; it ran year-round in 1960, but most tropical cyclones tend to form in the northwestern Pacific Ocean between June and December. These dates conventionally delimit the period of each year when most tropical cyclones form in the northwestern Pacific Ocean.
The 1963 Pacific typhoon season has no official bounds; it ran year-round in 1963, but most tropical cyclones tend to form in the northwestern Pacific Ocean between June and December. These dates conventionally delimit the period of each year when most tropical cyclones form in the northwestern Pacific Ocean.
The climate of the Arctic is characterized by long, cold winters and short, cool summers. There is a large amount of variability in climate across the Arctic, but all regions experience extremes of solar radiation in both summer and winter. Some parts of the Arctic are covered by ice year-round, and nearly all parts of the Arctic experience long periods with some form of ice on the surface.
The Arctic Ocean is the smallest and shallowest of the world's five major oceans. It spans an area of approximately 14,060,000 km2 (5,430,000 sq mi) and is known as the coldest of all the oceans. The International Hydrographic Organization (IHO) recognizes it as an ocean, although some oceanographers call it the Arctic Mediterranean Sea. It has been described approximately as an estuary of the Atlantic Ocean. It is also seen as the northernmost part of the all-encompassing World Ocean.
The Braer Storm was the most intense extratropical cyclone ever recorded over the northern Atlantic Ocean, as well as the strongest recorded worldwide at the time, though this was later surpassed by a stronger system in the Southern Pacific in October 2022. Developing as a weak frontal wave on 8 January 1993, the system moved rapidly northeast. The combination of the absorption of a second low-pressure area to its southeast, a stronger than normal sea surface temperature differential along its path, and the presence of a strong jet stream aloft led to a rapid strengthening of the storm, with its central pressure falling to an estimated 914 hPa on 10 January. Its strength was well predicted by forecasters in the United Kingdom, and warnings were issued before the low initially developed.
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 November 2011 Bering Sea cyclone was one of the most powerful extratropical cyclones to affect Alaska on record. On November 8, the National Weather Service (NWS) began issuing severe weather warnings, saying that this was a near-record storm in the Bering Sea. It rapidly deepened from 973 mb (28.7 inHg) to 948 mb (28.0 inHg) in just 24 hours before bottoming out at 943 mbar, roughly comparable to a Category 3 or 4 hurricane. The storm had been deemed life-threatening by many people. The storm had a forward speed of at least 60 mph (97 km/h) before it had reached Alaska. The storm began affecting Alaska in the late hours of November 8, 2011. The highest gust recorded was 93 mph (150 km/h) on Little Diomede Island. One person was reported missing after being swept into the Bering Sea, and he was later pronounced dead.
Hurricane Sandy was the sixth-costliest Atlantic hurricane on record. It lasted for over a week in late October-early November 2012. Classified as the eighteenth named storm, tenth hurricane, and second major hurricane of the annual hurricane season, Sandy originated from a tropical wave on October 22. Performing a small loop over the central Caribbean Sea, the system intensified into a tropical storm a day later and became the final hurricane of the season before briefly coming ashore the coast of Jamaica on October 24. After emerging between Jamaica and Cuba, Sandy began a period of rapid intensification into a Category 3 hurricane on the Saffir–Simpson hurricane wind scale, with maximum sustained winds of 115 mph (185 km/h). It made landfall at this intensity near Santiago de Cuba on October 25.
The Arctic ice pack is the sea ice cover of the Arctic Ocean and its vicinity. The Arctic ice pack undergoes a regular seasonal cycle in which ice melts in spring and summer, reaches a minimum around mid-September, then increases during fall and winter. Summer ice cover in the Arctic is about 50% of winter cover. Some of the ice survives from one year to the next. Currently, 28% of Arctic basin sea ice is multi-year ice, thicker than seasonal ice: up to 3–4 m (9.8–13.1 ft) thick over large areas, with ridges up to 20 m (65.6 ft) thick. The regular seasonal cycle there has been an underlying trend of declining sea ice in the Arctic in recent decades as well.
The November 2014 Bering Sea cyclone was the most intense extratropical cyclone ever recorded in the Bering Sea, which formed from a new storm developing out of the low-level circulation that separated from Typhoon Nuri, which soon absorbed the latter. The cyclone brought gale-force winds to the western Aleutian Islands and produced even higher gusts in other locations, including a 97 miles per hour (156 km/h) gust in Shemya, Alaska. The storm coincidentally occurred three years after another historic extratropical cyclone impacted an area slightly further to the east.
During 2015, tropical cyclones formed within seven different tropical cyclone basins, located within various parts of the Atlantic, Pacific and Indian Oceans. During the year, a total of 134 tropical cyclones had formed this year to date. 92 tropical cyclones had been named by either a Regional Specialized Meteorological Center (RSMC) or a Tropical Cyclone Warning Center (TCWC).
