Waiting for Milton

Hurricane: The term comes from the Taíno word hurucane, which means “evil spirit of the wind.”Spanish explorers brought the word to Europe, where it became common in English.

Tropical cyclone: A generic term used in the Indian Ocean and Coral Sea to describe storms that are called hurricanes or typhoons in other areas.

Typhoon: The term used in the Western Pacific for tropical cyclones.

Medicanes: An informal term for storms that form over the Mediterranean Sea and have characteristics similar to hurricanes.

Storm eye: The center of a hurricane, where conditions are calmer and winds are light.

Eye wall: The band of storms that surrounds the eye, where the most severe weather occurs.

Rain bands: Bands that extend from the cyclone and can produce heavy rain, wind, and tornadoes.

Tropical depression: A tropical cyclone with sustained winds of less than 39 mph.

Tropical storm: A tropical cyclone with sustained winds of 39–78 mph.

Category: A rating for the damage potential of a hurricane, with Category 1 having the lowest potential and Category 5 having the highest.

Atmospheric Pressure: The pressure exerted by the atmosphere at a given point. Its measurement can be expressed in several ways, including millibars and inches of mercury (Hg). Average sea level pressure is 1013.25 millibars or 29.92 inches of mercury. A drop in atmospheric pressure usually indicates the approach of a storm, such as a hurricane.

Beaufort Wind Scale: A system for estimating and reporting wind speeds. It is based on the visible effects of wind upon land objects (such as vegetation) and/or sea surface conditions such as white caps and foam. The scale was devised by Sir Francis Beaufort (1777-1857), hydrographer to the British Royal Navy.

Convection: Hurricanes develop over warm tropical oceans where the sea surface temperature is ~26.5 C (80 F) or warmer. In weather processes, there is circulation of fluid (air) that serves to equalize temperatures. An example is air flow between ocean and land during day and during night. Hurricanes use warm ocean waters for convection, often allowing for an increase in strength. Warmer water allows for an increase in storm strength.

Data Buoys: Instrumented buoys placed throughout United States coastal and ocean waters that collect and relay data or information on air and water temperature, wind speed, air pressure, and wave conditions through several media. For hurricanes, these buoys are used to gather information to help predict hurricane strengthening or weakening and direction of movement.

Dropsonde: A weather reconnaissance device designed to be dropped from an airplane. The dropsonde includes meteorological instruments attached to a parachute. A vertical profile of the atmosphere is returned to meteorologist’s computers as the dropsonde collects the data as it descends from the airplane to the ocean surface. Dropsondes are used by the Hurricane Hunter aircrafts to obtain the minimum central pressure in the eye of the hurricane, and conditions throughout the storm.

Fetch: The area over which the wind blows steadily. The greater the fetch, the greater the wave height. In a hurricane, fetch, wind speed, and wind direction associated with the storm will determine the storm surge as the storm moves landward.

Forward velocity: The speed at which a hurricane moves along its path. Slow-moving hurricanes (those with a low forward velocity) provide more opportunity for people to prepare.

Gale: On the Beaufort Wind Scale, defined as winds with speeds from 28 to 55 knots (32 to 63 miles per hour). “Gale force winds” are often associated with the outer portion hurricanes.

Gulf Stream: The warm, swift, relatively narrow ocean current that flows from south to north off the southeast Atlantic coast of the United States. The warm waters of the Gulf Stream often feed hurricanes by providing warm water that might be patchy elsewhere.

Gust: A sudden significant increase in or rapid fluctuations of wind speed. Peak wind speed must reach at least 16 knots (18 miles per hour); the duration is usually less than twenty seconds. Hurricane gusts have speeds 10mph or greater faster than a hurricane’s sustained wind speed.

Hurricane Warning : A formal advisory issued by forecasters at the National Hurricane Center when they have determined that hurricane conditions are expected in a coastal area or group of islands within a 24 hour period. A warning is used to inform the public and marine interests of the storm’s location, intensity, and movement.

Hurricane Watch: A formal advisory issued by forecasters at the National Hurricane Center when they have determined that hurricane conditions are a potential threat to a coastal area or group of islands within a 24 to 36 hour period. A watch is used to inform the public and marine interests of the storm’s location, intensity, and movement.

Low Latitudes: Latitudes between 30 and 0 degrees North and South of the equator. Also referred to as the tropical or torrid region. Most hurricanes develop at low latitudes (where waters are warmest).

Low Pressure System: An area of a relative pressure minimum that has converging winds and rotates in the same direction as the earth. This is counterclockwise in the Northern Hemisphere and clockwise in the Southern Hemisphere. Also known as a cyclone, it is the opposite of an area of high pressure (anticyclone).

Maximum sustained winds: This describes the hurricanes’ steady winds. Unlike hurricane gusts, maximum sustained winds must last over twenty seconds continuously. This determines the category of the hurricane on the Saffir-Simpson Scale.

Saffir-Simpson Scale: This scale classifies hurricanes based on their intensity, and is used to predict how damaging the hurricane will be to property. Saffir-Simpson classifies hurricanes from a scale of 1 (minimal) to 5 (catastrophic.)

Category Central Pressure Winds Surge
1 — Minimal Greater than 980 mb or 28.94 in 74 to 95 mph or 64 to 83 kts 4 to 5 feet
2 — Moderate 965 to 979 mb or 28.50 to 28.91 in 96 to 110 mph or 65 to 96 kts 6 to 8 feet
3 — Extensive 945 to 964 mb or 27.91 to 28.47 in 111 to 130 mph or 97 to 113 kts 9 to 12 feet
4 — Extreme 920 to 944 mb or 27.17 to 27.88 in 131 to 155 mph or 114 to 135 kts 13 to 18 feet
5 — Catastrophic less than 920 mb or 27.17 in greater than 155 mph or 135 kts greater than 18 feet

Storm surge: The increase in sea water height from the level that would occur under calm conditions. It is estimated by subtracting the normal tide from the recorded water level of the storm. Although the largest storm surges are associated with hurricanes, smaller low pressure systems and winds associated with fronts can cause an increase in the sea level if wind and fetch are cooperating. It is estimated by subtracting the normal astronomic tide from the observed storm tide. Learn more about storm surge in this NOAA National Hurricane Center “Introduction to Storm Surge” education resource.

Subtropical: The region between the tropical and temperate regions, an area between 35° and 40° North and South latitudes. This is generally an area of semi-permanent high pressure.

Subtropical waters: Also known as the semi-tropics, subtropical waters are in the region between the tropics (23.5 degrees north and south of the equator) and approximately 35 degrees latitude.

Swell: Ocean waves that have traveled out of the area where they were generated. Swell characteristically exhibits a more regular and longer period and has flatter wave crests than waves within their fetch. The swell generated by hurricanes that are offshore can cause big waves at the coast and set up dangerous rip currents.

Wind Direction: The direction from which the wind is blowing. For example, an easterly wind blows from the east, not toward the east. It is reported with reference to true north, or 360 degrees on the compass, and expressed to the nearest 10 degrees, or to one of the 16 points of the compass (N, NE, WNW, etc.).

Wind Shear: The rate of change of wind speed or direction with distance. Vertical wind shear is rate of change of the wind with respect to altitude. Horizontal wind shear is the rate of change on a horizontal plane. In a hurricane, vertical wind shear can cause significant weakening of the system.

Wind Speed: The rate of the motion of the air per unit of time. It can be measured with several types of instruments such as an anemometer, and may be reported using different units including knots (nautical miles per hour), miles per hour, or meters per second.

So now you know…..