"each flag is used to indicate a hurricane force wind warning (the use of one such flag denotes a storm warning or a tropical storm warning). Hurricane force wind warning A hurricane force wind warning is a warning issued by the National Weather Service of the United States when sustained winds or frequent gusts of 64 knots (118 km/h, 74 mph) or greater are either being observed or are predicted to occur. The winds must not be directly associated with a tropical cyclone, or a hurricane warning will be issued. If winds are lighter than 64 knots, a storm warning"
"at this altitude, updraughts with speeds that can exceed . Such an updraught speed corresponds to the wind speed of a small hurricane. The speed can even exceed . The maximum number in the Beaufort scale is 12 (""hurricane force"" wind) and is assigned to wind speeds of 64 knots or greater. If the Beaufort scale were extended, these updraughts would have a Beaufort number of 14 ""in the vertical direction"". The turbulence is then ""extreme"" at this altitude. Moreover, the diameters of the updraught columns vary between 2 km (air mass thunderstorm) and 10 km (supercell thunderstorm). The height"
"winds in hurricanes would be 23 in the scale. Today, hurricane-force winds are sometimes described as Beaufort scale 12 through 16, very roughly related to the respective category speeds of the Saffir–Simpson hurricane scale, by which actual hurricanes are measured, where Category 1 is equivalent to Beaufort 12. However, the extended Beaufort numbers above 13 do not match the Saffir–Simpson scale. Category 1 tornadoes on the Fujita and TORRO scales also begin roughly at the end of level 12 of the Beaufort scale, but are independent scales – although the TORRO scale wind values are based on the 3/2 power"
"Beaufort scale The Beaufort scale is an empirical measure that relates wind speed to observed conditions at sea or on land. Its full name is the Beaufort wind force scale. The scale was devised in 1805 by the Irish hydrographer Francis Beaufort (later Rear Admiral Sir Francis Beaufort), a Royal Navy officer, while serving on HMS ""Woolwich"". The scale that carries Beaufort's name had a long and complex evolution from the previous work of others (including Daniel Defoe the century before) to when Beaufort was Hydrographer of the Navy in the 1830s when it was adopted officially and first used"
"used in Taiwan and mainland China, which are often affected by typhoons. Internationally, WMO Manual on Marine Meteorological Services (2012 edition) defined the Beaufort Scale only up to force 12 and there was no recommendation on the use of the extended scale. Wind speed on the 1946 Beaufort scale is based on the empirical relationship: Where ""v"" is the equivalent wind speed at 10 metres above the sea surface and ""B"" is Beaufort scale number. For example, ""B"" = 9.5 is related to 24.5 m/s which is equal to the lower limit of ""10 Beaufort"". Using this formula the highest"
"law relating wind velocity to Beaufort force. Wave heights in the scale are for conditions in the open ocean, not along the shore. The wind speeds in different units are not mathematically equivalent; e.g. 12–19 km/h is not equivalent to 8–12 mph, and both are not equivalent to 7–10 knots. The reason is that the Beaufort scale is not an exact nor an objective scale. It was based on visual and subjective observation of a ship and of the sea. The corresponding integral wind speeds were determined later, but the values in different units were never made equivalent. The scale"
"force. Gradually curving northwestward, the storm continued to gain power and, on August 18, it achieved wind speeds corresponding to Category 2 intensity on the modern-day Saffir-Simpson Hurricane Scale. This scale was devised in 1971 to categorize tropical cyclones based on their maximum sustained winds. The storm is estimated to have maintained winds of approximately 100 mph (155 km/h) for several days as it passed well to the north of the Lesser Antilles. As the hurricane turned more northerly still, approaching the United States, it strengthened to major hurricane intensity, Category 3, on August 22. At this point, it peaked"
"warning. These designations were standardized nationally in 2008, whereas ""light wind"" can refer to 0 to 12 or 0 to 15 knots and ""moderate wind"" 12 to 19 or 16 to 19 knots, depending on regional custom, definition or practice. Prior to 2008, a ""strong wind warning"" would have been referred to as a ""small craft warning"" by Environment Canada, similar to US terminology. (Canada and the USA have the Great Lakes in common.) Beaufort scale The Beaufort scale is an empirical measure that relates wind speed to observed conditions at sea or on land. Its full name is the"
"force for coastal areas, between and . The definition is very non-standard. A common alternative definition of the maximum is . The most common way of measuring wind force is with the Beaufort scale which defines a gale as wind from to . It is an empirical measure for describing wind speed based mainly on observed sea conditions. On the original 1810 Beaufort wind force scale, there were four different ""gale"" designations whereas generally today there are two gale forces, 8 and 9, and a near gale 7: The word ""gale"" is derived from the older ""gail"", but its origin"
"scale, decoded as 32–38 mph, or a ""moderate Gale"". Beaufort, like other patrons of exploration, has had his name given to many geographical places. Among these: Beaufort created the Beaufort cipher. It is a substitution cipher similar to the Vigenère cipher. Francis Beaufort Rear Admiral Sir Francis Beaufort, KCB, FRS, FRGS, FRAS, MRIA (; 27 May 1774 – 17 December 1857) was an Irish hydrographer and officer in the Royal Navy. Beaufort was the creator of the Beaufort Scale for indicating wind force. Francis Beaufort was descended from French Protestant Huguenots, who fled the French Wars of Religion in the"
"indicating a storm warning with northwesterly winds. By late afternoon, the storm signal flags were replaced with a vertical sequence of red, white, and red lanterns, indicating that a hurricane with winds over 74 mph (119 km/h) was coming. (The word ""hurricane"" here does not refer to a tropical cyclone, but to Force 12 winds on the Beaufort scale.) The winds on Lake Superior had already reached 50 mph (80 km/h), and an accompanying blizzard was moving toward Lake Huron. By Saturday, the storm's status had been upgraded to ""severe"". The storm was centered over eastern Lake Superior, covering the"
"F1 corresponds to the twelfth level of the Beaufort scale, and F12 corresponds to Mach number 1.0. F0 was placed at a position specifying no damage (approximately the eighth level of the Beaufort scale), in analogy to how the Beaufort's zeroth level specifies little to no wind. From these wind speed numbers, qualitative descriptions of damage were made for each category of the Fujita scale, and then these descriptions were used to classify tornadoes. The diagram on the right illustrates the relationship between the Beaufort, Fujita, and Mach number scales. At the time Fujita derived the scale, little information was"
"Change in wind direction is indicated by ""veering"" (clockwise change) or ""backing"" (anti-clockwise change). Winds at or above force 8 are also described by name for emphasis, i.e., Gale 8, Severe Gale 9, Storm 10, Violent Storm 11 and Hurricane force 12. The word ""force"" is only officially used when announcing force 12 winds. Visibility is given in the format ""Good"", meaning that the visibility is greater than ; ""Moderate"", where visibility is between nautical miles; ""Poor"", where visibility is between 1,000 metres and two nautical miles and ""Fog"", where visibility is less than . When severe winter cold combines"
"accompanied by Category 5-force winds on the modern-day Saffir–Simpson hurricane wind scale, defined as 1-minute maximum sustained winds of at least 157 mph (252 km/h). Despite the reading, a 1993 analysis by weather historian José Fernández-Partagás calculated a corrected sea-level pressure at 938 mbar (27.70 inHg); even so, the value maintained the hurricane as the most intense in recorded history. It arrived at Key West the morning of 11 October, soon after its departure from Cuba, with undiminished intensity. The storm gradually meandered toward Tampa Bay, and eventually arrived on that afternoon of 11 October, its effects persisting through the"
"with sustained winds of 75 mph (120 km/h). Just offshore, buoys recorded winds near hurricane-force and enormous waves up to 82 ft (25.1 m) tall. Onshore, strong winds and heavy rain affected much of Atlantic Canada; rainfall peaked at 3 in (76.5 mm) in Edmundston, New Brunswick. In Quebec, heavy rains from the storm amounted to at least 1.9 in (48.2 mm); however, reports from a storm chaser indicate that up to 3.2 in (82 mm) may have fallen in Passes-Dangereuses. The strongest winds onshore reached 84 mph (135 km/h) on Beaver Island. Sustained winds of at least likely affected"
"ice crystals at atmospheric levels. Larger hailstones are capable of producing damage to property, and particularly with very large hailstones, resulting in serious injury or death due to blunt-force trauma induced by the impact of the hailstones. Hailstone size is typically correspondent to the size of an object for comparative purposes. <nowiki>*</nowiki> <br> The Beaufort scale is an empirical measure that correlates wind speed to observed conditions at sea or on land. The Enhanced Fujita scale, an updated version of the original Fujita scale that was developed by Ted Fujita with Allen Pearson, assigns a numerical rating from EF0 to"
"Wind speed Wind speed, or wind flow velocity, is a fundamental atmospheric quantity caused by air moving from high to low pressure, usually due to changes in temperature. Note that wind direction is usually almost parallel to isobars (and not perpendicular, as one might expect), due to Earth's rotation. Wind speed affects weather forecasting, aviation and maritime operations, construction projects, growth and metabolism rate of many plant species, and countless other implications. Wind speed is now commonly measured with an anemometer, but can also be classified using the older Beaufort scale, which is based on personal observation of specifically defined"
"to a deep depression and later a cyclonic storm. Two days later, a subtropical ridge over Southeast Asia nudged Forrest toward the north, and it regained organized convection. Early on November 18, the storm attained hurricane-force winds as favorable outflow and upper-level winds aided intensification. Strengthening continued through early on November 20, at which time Forrest reached its peak intensity with winds of 230 km/h (145 mph), a Category 4-equivalent cyclone on the Saffir–Simpson hurricane scale. The IMD assessed three-minute sustained winds to have been 185 km/h (115 mph), making it a modern-day ""extremely severe cyclonic storm"", and its barometric"
"Francis Beaufort Rear Admiral Sir Francis Beaufort, KCB, FRS, FRGS, FRAS, MRIA (; 27 May 1774 – 17 December 1857) was an Irish hydrographer and officer in the Royal Navy. Beaufort was the creator of the Beaufort Scale for indicating wind force. Francis Beaufort was descended from French Protestant Huguenots, who fled the French Wars of Religion in the sixteenth century. His parents moved to Ireland from London. His father, Daniel Augustus Beaufort, was a Protestant clergyman from Navan, County Meath, Ireland, and a member of the learned Royal Irish Academy. His mother Mary was the daughter and co-heiress of"
"becoming a significant storm over New England before lifting northward through Quebec into the Davis Strait. At this time, maximum sustained winds reached 164 kilometers per hour (102 mph) in coastal areas (equal to a Category 2 hurricane on the Saffir-Simpson hurricane scale), with wind gusts of up to 188 kilometers per hour (116 mph). By February 6, this extratropical cyclone was absorbed by another system in the northern Canadian archipelago. Caribou, Maine, recorded one of its lowest pressures on record, with much of New England recording its lowest values for the month of February,with a reading of . Winds"
"responsible for this and for the addition of the land-based descriptors. The measure was slightly altered some decades later to improve its utility for meteorologists. Today, many countries have abandoned the scale and use the metric system based units, m/s or km/h, instead, but the severe weather warnings given to the public are still approximately the same as when using the Beaufort scale. The Beaufort scale was extended in 1946, when forces 13 to 17 were added. However, forces 13 to 17 were intended to apply only to special cases, such as tropical cyclones. Nowadays, the extended scale is only"
"on November 10 as it headed towards Jamaica. Late on November 11, the system brushed the eastern tip of Jamaica as a strong tropical storm, with maximum winds estimated at 70 mph (120 km/h). Several hours later, the storm intensified into what would now be classified a Category 1 hurricane on the Saffir–Simpson Hurricane Scale. During the afternoon of November 12, the hurricane made landfall in northern Haiti, in Nord-Ouest, with winds of 85 mph (140 km/h). After briefly moving over land, the storm entered the Atlantic Ocean and turned east-northeast and further accelerated. Early on November 13, the hurricane"
"winds of 240 km/h (150 mph). Six hours later, the JTWC estimated 1-minute sustained winds of 285 km/h (180 mph), equivalent to Category 5 on the Saffir–Simpson scale, while noting ""an extremely favorable environment"", and that the eye became even more symmetric within intense convection. Outflow enhanced by a strong anticyclone over Meranti fueled the intensification, and the typhoon peaked in intensity on September 13 while passing through the Luzon Strait. The JMA estimated peak 10-minute sustained winds of 220 km/h (140 mph) and a minimum barometric pressure of 890 hPa (mbar; 26.28 inHg), while the JTWC estimated peak 1-minute"
"predicted large-scale, cyclonic windstorms with potential for significant land-based wind impacts. This may result in names being allocated to events that are below the traditional Beaufort scale definition of a storm. A storm will be named when it is deemed able to have a ""substantial"" impact on the UK or Ireland. Met Éireann names any storm which triggers a status Orange or Red weather warning focusing on wind, though consideration was also given to rain and snow events in 2016–17. The basis for such as outlined on their weather warning service are mean wind speeds in excess of 40 mph"
"lake wind advisory is issued for winds just below this range, because unobstructed winds across the open waters of a lake are normally faster than across land. The wind speed that triggers the advisory has changed over time. Until the late 1960s, the threshold was 32 to 38 miles per hour (or 28 to 33 knots). At some point, the lower limit was reduced to 23 miles per hour (20 knots). Today, however, most places have standardized on 25 to 38 miles per hour (22 to 33 knots), encompassing the combined ranges of forces 6 and 7 on the Beaufort"
"states: Force 8, defined as ""Gale"". Wind speed 39-46 mph, equal to 34-40 knots. Inland, twigs break off trees; progress generally impeded. At sea, moderately high waves of greater length; edges of crests begin to break into spindrift; foam is blown in well-marked streaks along the direction of the wind. Relatedly, ""spindrift"" can also be used to describe fine sand or snow that is blown off by the wind. ""Spindrift"" is a southern English word, ""Spoondrift"" a northern or Scottish word. The Scottish word ""spoondrift"" can be used to describe fine snow that is blown off the hills by the"
"the presence of a tropical cyclone, which was confirmed by the next day. Modern researchers determined that the system developed on September 25 about 220 miles (350 km) east of Guadeloupe. For most of its duration, the system maintained a northwest track, reaching hurricane status on September 27. Later that day, a barometric pressure of 977 mbar, suggesting winds of 90 mph (150 km/h). Its intensification rate slowed on September 28, before strengthening continued on October 1. The winds reached 115 mph (185 km/h), which is the equivalent of a major hurricane, or Category 3 on the Saffir-Simpson scale. Around"
"in the subtropical ridge. Though its eyewall was open on the north side, favorable conditions led forecasters to predict Florence passing near Bermuda as a strong Category 2 hurricane. The inner core of convection became ragged-looking on satellite imagery, and based on reports from Hurricane Hunters it is estimated the hurricane attained peak winds of 90 mph (150 km/h) late on September 10. Subsequent to further erosion of the eyewall, the hurricane weakened, and on September 11 passed about 60 miles (95 km) west of Bermuda with winds of 85 mph (135 km/h). The overall cloud pattern became slightly better"
"than 300 km/h (160 kn; 83 m/s) were recorded, with a maximum 5-minute mean speed of 176 km/h (95 kn; 110 mph; 49 m/s), the extreme gust factor was in the order of 2.27–2.75 times the mean wind speed. The pattern and scales of the gusts suggest that a mesovortex was embedded in the already strong eyewall of the cyclone. The now second highest surface wind speed ever officially recorded is 372 km/h (231 mph; 103 m/s) at the Mount Washington (New Hampshire) Observatory: 6,288 ft (1917 m) above sea level in the US on 12 April 1934, using a"
"mph (178 km/h) or higher. Shortly after, the cyclone reached its peak intensity as a low-end Category 4 hurricane on the Saffir-Simpson Hurricane Scale, with winds of 140 mph (220 km/h) while located about 410 mi (660 km) south-southwest of the southern tip of Baja California Sur. Not long after reaching peak intensity, the storm moved over cooler waters, causing the eyewall to deteriorate and cloud tops to warm. The next day, the eye of Howard disappeared from satellite imagery, leading to the cyclone being downgraded to a Category 2 hurricane. Continued deterioration of the system caused rapid weakening, with"
"At 0600 UTC on August 17, the cyclone strengthened into a Category 1 hurricane on the Saffir–Simpson hurricane wind scale; within 36 hours, Bill entered a period of rapid deepening and intensified into a major hurricane with winds of 115 mph (185 km/h). Passing well northeast of the Lesser Antilles, Bill attained its peak intensity with maximum sustained winds of 130 mph (215 km/h) and a minimum barometric pressure of 943 mb (hPa; 27.85 inHg) on August 19 and August 20, respectively. Thereafter, an approaching trough induced higher vertical wind shear across the region, causing slow weakening of the hurricane;"
"scale. Winds strong enough to trigger a small craft advisory may be referred to as being advisory-force. Conversely, winds just above this intensity (39-57 miles per hour) are called gale-force, and have a separate associated warning. Occasionally an informal lesser advisory, known as ""small craft exercise caution"", is issued for wind speeds lighter than those that call for a small craft advisory. Criteria for this vary in different localities; sometimes a range of 19 to 24 miles per hour (17 to 21 knots) is observed, or in some places 17 to 23 miles per hour (15 to 19 knots) may"
"27, the Regional Specialized Meteorological Center Météo-France in La Réunion classified the system as ""Disturbance 14"". Drifting slowly east, a prominent feeder band developed along the system's eastern side; however, this band disrupted low-level inflow of warm, moist air and suppressed convection over the circulation center. Though convection later began to consolidate into a small central dense overcast (CDO) feature by March 28, continued disruption of the low-level inflow prevented much development. Météo-France noted that despite forecasting the storm to peak as a moderate tropical storm, with winds of 75 km/h (45 mph), there was potential for rapid intensification due"