A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | Z
- 100-year Flood (25-year Flood, etc.):
- Calculated to the maximum flood level expected to occur once every 100 years, although floods at the calculated level may, in fact, occur in two consecutive years. The nomenclature is about rarity and likeliness, often deduced from historical records. Another way of thinking about this, which is also sometimes used by experts, is to convert the time span into a percentage chance. So, a 100-year flood has a one percent chance of occurring in a given year; a 50-year flood, two percent chance; 10-year flood, 10 percent chance; and so on.
- Advisory:
- A term often used in news when alerting of potentially hazardous conditions resulting from adverse weather. It has special meaning in phrases "Urban and Small Stream Advisory" (See below.) and "Small Craft Advisory." Specific terms used to refer to announcements about floods include Flood Watch, Flood Warning, and Flood Potential Outlook (See below.)
- Arroyo:
- A water-carved gully or normally dry creek bed. Arroyos can fill with fast-moving water very quickly. Flash flooding in an arroyo can take just seconds to develop.
- Base Flood Elevation (BFE):
- A measurement of the elevation or height that a flood is expected to reach, above mean sea level. For various purposes BFE can be set at different levels such as the 100-year flood extent. Some local governments choose to use higher-frequency flood events as their BFE for certain activities (like storm-water management), while using lower frequency events for others (such as certain construction or tie-down regulations). The regulations of the National Flood Insurance Program (NFIP) focus on development in the 100-year floodplain.
- Coastal Flood:
- Usually refers to wind generated waves resulting from tropical storms and hurricanes or intense offshore low pressure systems that drive ocean water inland. These conditions can cause significant flooding. Escape routes can be cut off and blocked by high water. Coastal flooding can also be produced by sea waves called tsunamis, formerly confused with tidal waves, which are produced by earthquakes, volcanic activity and other major disturbances in the sea.
- Cyclone:
- An area of low pressure around which winds blow counterclockwise in the Northern Hemisphere and clockwise in the Southern Hemisphere. Cyclone is also the term used for a hurricane in the Indian Ocean and in the West Pacific Ocean. Cyclones usually signal unsettled weather. A hurricane is a (warm-core) cyclone.
- Debris Jams:
- Occur where debris—both trash from destroyed structures and natural materials like fallen trees—builds up to create a temporary dam. While the damming lasts, there can be flooding upstream. When the pressure of the water eventually breaks the jam, there can be flash flooding downstream. (In other parts of the world, the jams are frequently ice jams, not known to occur in Hawaii.)
- Disaster Supply Kit:
- See Survival Kit.
- Drill:
- A practice run of predetermined actions such as your flood escape plan, including family reunification, supply management and whatever efforts are required to inform loved ones in other places that you are safe or in need. A Drill is an especially good idea when children are in the household. Not only will it mean that they know what to do and what not to do in the event of a flood, but they will feel more confident taking action if the real emergency ever comes.
- Evacuation Route:
- An identified roadway and/or non-road passageway to an area of safety. Having a planned evacuation route is vital if you live in or frequently visit a place that floods easily or frequently.
- Extreme Conditions:
- A phrase used often in broadcast weather. It should be taken as a signal that current or potential weather conditions require your attention.
- FEMA:
- The Federal Emergency Management Agency. This federal agency is charged with managing government responses after a damaging event such as a major flood. FEMA may be tasked to help with recovery after any kind of natural or man-made disaster. The agency is also an important resource for flood insurance information, flood (and other disaster) preparedness information, and much more.
- Flash Floods:
- Occur within a few minutes or hours of excessive rainfall, a dam or levee failure, or a sudden release of water held by a debris jam. Flash floods can roll boulders, tear out trees, destroy buildings and bridges, and scour out new channels. Rapidly rising water can become very deep, depending on terrain. The precipitation that produces a flash flood can also trigger catastrophic mud slides. You will not always have a warning that these deadly, sudden floods are coming, but some areas are more prone to flash flooding and are known to local people—often even marked with warning signs. Most flood deaths are due to flash floods.
- Flash Flood Warning:
- A flash flood is imminent. You should take immediate action to secure your safety. Move to higher ground without delay.
- Flash Flood Watch:
- A flash flood is possible in the area. You should stay alert to changing conditions and be prepared for the possibility of a Flash Flood Warning being issued at any moment.
- Flood:
- Any condition, meteorological or otherwise in which normally dry land is covered by standing or moving water. Flash flooding, according to a report by the Alabama Cooperative Extension, is the No. 1 cause of death associated with thunderstorms; and NOAA reports that flooding is the No. 2 weather-related cause of death. (In Hawaii, fatalities related to high surf outpace flooding significantly.)
- Flood Insurance Rate Map (FIRM):
- Usually refers to a map consolidating flood risk conditions which are considered by the insurance industry for setting rates for flood insurance or for determining that it will not be offered in an area. The set of Hawaii maps offered by Geology.com is not consolidated in that way, but shows terrain, rivers and lakes, political divisions and major roadways, all of which are FIRM factors. If you are not an insurance agent or insurance shopper, you might not need an official FIRM. While the Federal Emergency Management Agency (FEMA) map service center has no FIRM maps, for example, for South Maui, they do have viewable and purchasable "Public Flood Maps" showing the flood risk zones and other important flood risk data.
- Flood Plain (also floodplain):
- A level land area subject to periodic flooding from a contiguous body of water. Floodplains are described by the frequency of expected flooding. An "annual floodplain" is expected to flood once each year, a "100-year floodplain" is expected to flood only once in a century.
- Flood Potential Outlook:
- A long range (36-72 hours) outlook issued by a local National Weather Service Office when forecast meteorological conditions indicate that a significant heavy rainfall event may occur that would either cause flooding or aggravate an existing flooding situation. It is issued when conditions are favorable for flooding; however, either uncertainty or the time frame precludes the forecaster from issuing either a Flood Watch or Flash Flood Watch.
- Flood Warning:
- A flood is imminent. You should take immediate action to secure your safety. Move to higher ground without delay.
- Flood Watch:
- A flood is possible in the area. You should stay alert to changing conditions and be prepared for the possibility of a Flash Flood Warning being issued at any moment.
- Floodway:
- The regular channel of a river, stream, or other watercourse, plus the adjacent land areas—usually regulated by government and legally required to be kept clear of development—that are required in order to discharge the predicted water of a 100-year flood (q.v.) without cumulatively increasing the water surface elevation by more than one foot. If the floodway is infringed by construction or by plantings that may tend to withstand the flood waters, it will result in a deeper and potentially more destructive flood at or downstream of the infringing obstruction(s).
- Floodway Fringe:
- Refers to that portion of a floodplain which is inundated by floodwaters but is not within the defined floodway (q.v.). Floodway fringes serve as temporary "storage areas" for floodwaters.
- Gulch:
- A relatively deep, commonly V-shaped valley or depression formed by erosion (from moving water). It may contain a stream or a dry creek bed. Frequently, flash floods will course down gulches. In fact, many lasting gulches in the Hawaiian Islands were probably carved into the modern shapes by repeated flash flooding.
- Higher Ground:
- Usually a safer place to be during a flood. When a flood warning urges movement to higher ground, you should move to a place that is safer from rising or rushing flood waters, but also a place from which you will be able to retreat without swimming, wading or otherwise entering the flood waters. A knoll in a floodplain surrounded by flood water, is not the sort of higher ground intended, for example. It may erode, it may weaken and dissolve into mud or it may be impossible to retreat safely.
- Hurricane:
- A severe tropical cyclone with sustained winds of 74 miles per hour (64 knots) or greater. Major hazards include high winds, heavy rainfall, flooding, storm surge and high surf. Hurricane is the term used for such systems located in the Central or East Pacific regions. Systems of the same intensity occurring in the West Pacific are called typhoons. Five categories of hurricanes of various intensities have been established with ratings from 1 for the weakest to 5 for the strongest.
- Inundation:
- A flooding—by the rise and spread of water—of a land surface that is not normally submerged.
- Jams:
- Usually refer to debris jam in Hawaii where debris floating in or being pushed along by water—either trash like that from destroyed structures or natural materials like fallen trees—may build up to create a temporary dam. While the damming lasts, there can be flooding upstream. When the pressure of the water eventually breaks the jam, there can be flash flooding downstream.
- Knoll:
- A small, round-topped area of ground rising above lower, usually flat ground. A knoll is not usually a good choice when seeking higher ground in a flood. First, it will often become completely surrounded, stranding you. Second, it may be composed of soils incapable of withstanding moving floodwaters. Finally, if you are on a knoll, it is almost certain that you are going to have to enter potentially dangerous flood waters in order to move either back to your home or away to another safe location.
- Landslide:
- A geological phenomenon that causes the sudden or rapid movement of the ground or ground level materials (boulders, gravel, etc.), from higher to lower elevation. A landslide is usually gravity acting on an over-steepened slope or on ground made susceptible by previous landslide(s) or any many factors such as saturation by heavy rains or earthquakes. Vibrations from machinery, traffic, blasting and even thunder can trigger landslides on weak or weakened slopes. Rain- and flood-caused landslides can easily become mudslides (q.v.).
- Leeward:
- The opposite of windward. It means on the side of an island where there is less wind, usually (but not always) also meaning away from storms and other weather. In Hawaii, this means the south and west sides of the islands, away from the trade winds. Leeward areas of the islands are the areas protected by mountainous rises from the northeasterly trade winds. When the wind is blowing from another direction, as when Hawaii experiences Kona (southerly) winds, the usually leeward south and/or west sides of the islands become the windward coasts.
- Lightning:
- An abrupt electric discharge from cloud to cloud or from cloud to earth accompanied by the emission of light.
- Makai:
- A Hawaiian word that means toward the sea and is used to refer both to the direction of movement and the land or other resources found in that direction. A storm moving makai from any point is traveling toward the sea and away from higher ground.
- Mauka:
- A Hawaiian word that means toward the mountain and is used to refer to both that direction of movement and the land or other resources found in that direction. If rain is falling heavily in mauka areas, makai (q.v.) areas might see runoff, even flooding.
- Mudslide:
- A landslide (q.v.) in which the soil becomes saturated with water, usually recent or currently falling rain water, and falls as mud. Mudslides present somewhat different challenges and dangers than "dry" landslides.
- National Flood Insurance Program:
- A program managed by the Mitigation Division of FEMA which includes flood hazard mapping, floodplain management and the insurance itself.
- NOAA Weather Radio:
- A radio designed to receive warnings from the National Weather Service. NWS continuously broadcasts updated weather warnings and forecasts that can be received by NOAA Weather Radios, sold in many stores. Average range is 40 miles, depending on topography. NWS recommends purchasing a radio that has both a battery backup and a tone-alert feature which automatically sounds when a watch or warning is issued.
- Precipitation Intensities:
-
Ranging from mists to flooding rain. They are commonly described as follows:
- Mist is precipitation so light that it can sometimes hang in the air. Mist, in general, poses no threat of flood or damage. Although, by reducing visibility and/or promoting the growth of mold it may present some problems.
- Drizzle may also appear to float on air currents but, unlike either fog or mist, it does fall to the ground. Meteorologists have a variety of definitions of drizzle that depend either on the size of the droplets or the way they have formed, and an exact threshold to distinguish mist from drizzle is not established. Meteorologist Jeff Haby defines drizzle as light, moderate or heavy based on visibility being reduced to distances between one-half and one-quarter mile.
- Light Rain is defined variously by different meteorologists, but is generally precipitation of 0.10 inches an hour or less. Even light rain can cause flooding if the duration of the rainfall event is long enough or if the runoff conditions are extreme.
- Moderate Rain is defined as falling at up to 0.30 inches an hour. Moderate rain can possibly cause flooding if it lasts long enough or if conditions are such that rain must run off (rather than soak into the ground) and that runoff is concentrated in a small enough area.
- Heavy Rain is precipitation falling faster than 0.30 inches an hour. Heavy rain can certainly cause flooding. The likelihood of flooding depends on ground conditions and opportunities for the rain water to soak into the ground or to disperse over a large area for runoff.
- Flooding Rain (or Deluge) is high-intensity rainfall that can quickly cause flooding or flash flooding. On some terrain, as little as 0.50 or 0.75 inches of rain an hour can quickly and correctly be called flooding rain, although it is more common for the term to be used for even heavier rainfall or for rain that continues for many hours, even days. To illustrate, an August 1998 memo issued by NOAA, describing responses to a flood event of nearly a year before, says, "the criterion of .80 inches per hour was [then considered] insufficient for issuing a warning. Due to local terrain, vegetation factors, and intensity experiments it was found after the event that new criteria for the affected area included a rainfall rate of only .60 inches in 10 minutes. Ideally, guidance criteria should include temporal units much less than one hour." Flood prediction becomes more accurate and "flooding rain" is redefined as such studies are undertaken.
- Rain:
- Liquid droplets or precipitation of sufficient size, relative to the humidity/aridity of the air, to reach the ground without evaporating. Precipitation that crystallizes is snow. Frozen, it is sleet or hail. Water drops that evaporate in the air are virga. Rain is the only precipitation that presents the possibility of immediate flooding.
- Rate of Precipitation:
- Usually expressed in inches of rainfall in an hour or over a 24-hour period. A similar calculation using an average-year rate is used to describe general humidity or aridity. For example, one definition of a desert says it is a landscape that receives an annual average of less than 10 inches of rain. Except in extreme cases, the rate of precipitation described in inches-per-time-period only has meaning in a context of soil conditions, other recent precipitation, terrain, etc. With regard to one's home area or a familiar area, precipitation intensities (See above) will have more immediate meaning.
- River Flooding:
- Occurs when the river waters flow outside the river channel or when the waters flow over the river banks. This is a natural and inevitable part of life along a river. Some river flooding is seasonal. When annual rains, for example, fill river basins with too much water, too quickly. Torrential rains from decaying hurricanes or tropical systems can also produce river flooding.
- Severe Weather:
- Any weather that requires special vigilance to ensure safety. It is generally used to describe weather events that are potentially destructive such as thunderstorms and hurricanes, but is also applied to flooding rain and to rain that is—or is predicted to be—of long duration.
- Sheet Flooding:
- Occurs when storm water collects on the ground, especially already saturated ground, to a depth of several inches, eventually flowing makai, or down-slope, still in a shallow "sheet." Sheet flooding can be both sudden and dangerous.
- Statement (or Flood Statement, Flash Flood Statement, etc.):
- A message with additional information that is issued after a Flood Advisory, Flood Watch or Flood Warning. The announcement of the cancellation of a Flood Warning or an update on road closures, for example, would be a Statement. However, to add new areas to the extent of a Flood Warning, a new Flood Warning would be issued, not a Statement.
- Standing Water:
- A phrase used in reference to floods as well as during and immediately after rain events that have either been of long duration or included periods of heavy rain. It is important to remember that you cannot know what is in or beneath the surface of standing water. The roadbed may have given way leaving a dangerous sinkhole. There could be caustic chemicals in runoff or raw sewage from backed-up or broken underground drain pipes. Do not enter or drive through standing water, and do not allow children to play in standing water. Another danger associated with standing water is that the same conditions that allowed the current water to collect might suddenly repeat, turning standing water into rushing, even flash flooding water.
- Storm:
- The general term for a significant disturbance in the atmosphere. When a storm is low enough in the atmosphere to have an effect on the surface of the earth, it usually implies severe or potentially weather. It can be very important to hear what kind of storm is approaching: Wind storms can be destructive in some ways. Thunderstorms can be destructive in other ways, and can cause floods.
- Storm Surge:
- A coastal flooding condition brought on by an approaching or passing hurricane, typhoon, or cyclone.
- Super Typhoon:
- See Typhoon.
- Survival Kits:
- May need very different contents for different households. Whatever instructions you follow for putting your survival kit together, remember to add to it whatever items are specific to your needs. Special needs may be associated with an infant, a disabled person, a person taking medications, one needing glasses or a hearing aid, etc. PDC has compiled several resources for severe weather preparedness under the heading Create a Disaster Supply Kit
- Sustained:
- Continuing for some time. It is most commonly used in relation to wind, as when a meteorologist says, "sustained winds at 30 miles per hour with gusts up to 50 miles per hour." It is also used to refer to rain that continues over a relatively long time. Sustained rain, even if it is not heavy, can result in flooding.
- Thunder:
- The sound of the shockwave caused when lightning instantly heats the air around it to up to 54,000°F. That super-heated air expands rapidly, then contracts as it cools.
- Thunderstorm:
- A transient, sometimes violent storm of thunder and lightning, often accompanied by rain and sometimes hail. Even in Hawaii, thunderstorms have been known to deliver hail, to include lightning strikes that reach the ground, and to bring on tornadoes.
- Tidal wave:
- An obsolete term for "tsunami," a specific kind of ocean surge which can cause coastal flooding. The current usage of the term "tidal wave" does not refer to a tsunami. Instead, it refers to 1) a tidal bore, the large wave formed by the funneling of the incoming tide into a river or narrow bay, or 2) the crest of an ocean tide as it moves around the Earth. Tidal wave (2) is distinguished from ocean surface waves by the fact that it is caused by the gravitational pull of the sun and moon, not by wind friction which causes other waves.
- Tropical Cyclone:
- The general term for all cyclone circulations that originate over tropical waters.
- Tropical Depression:
- A rotary circulation at surface level with a highest constant wind speed of 38 miles per hour (33 knots).
- Tropical Disturbance:
- A moving area of thunder storms in the tropics that maintains an identity for 24-hours or more.
- Tropical Atorm:
- A distinct rotary circulation with constant wind speed in the 39-73 miles per hour (34-63 knots) range.
- Tsunami:
- A Japanese term derived from the characters "tsu," meaning harbor, and "nami," meaning wave. This term is now generally accepted by the international scientific community to describe waves in water produced by the displacement of the sea floor (and other more rare conditions). This is the phenomenon previously known as a "tidal wave."
- Typhoon:
- A large and powerful tropical cyclone, a low pressure area rotating counterclockwise and containing rising warm air that forms over warm water in the Western Pacific Ocean. A typhoon's winds are moving at 65 knots or faster. When the wind speed doubles, the cyclone is called a Super Typhoon.
- Urban and Small Stream Advisory:
- Issued when flooding of small streams, streets, and low-lying areas, such as railroad underpasses and urban storm drains, is occurring.
- Urban Flood:
- A phrase used to specifically speak of flooding caused or made worse by human activity such as the land being converted from fields or woodlands to roads and parking lots. The land loses its ability to absorb rainfall. Urbanization increases runoff 2 to 6 times over what would occur on natural terrain. During periods of urban flooding, streets can become swift moving rivers, while basements can become death traps as they fill with water.
- Warning (Flood/Flash Flood Warning):
- A (flash) flood has been reported or is imminent. You should take immediate action to secure your safety. You may have only seconds in which to act.
- Watch (Flood/Flash Flood Watch):
- A (flash) flood is possible in the area. You should stay alert to changing conditions. Be ready to evacuate at a moment's notice if you are in the watch area.
- Windward:
- The opposite of leeward. It means on the side from which the wind is blowing. There is more wind felt on the windward side because the area is between the sea and the protection of mountains. This often also means more rain and more effects from storms and other weather, although leeward storms do occur. The windward areas of the islands of Hawaii are usually the north and east coastal areas. When the wind is blowing from other than the northeast—is not trade wind—the meanings of the words "leeward" and "windward" change or reverse.
0-9
A
B
C
TopD
E
F
G
H
I
J
K
L
M
N
O
(empty)
P
Q
(empty)
R
S
T
U
V
(empty)
W
X
(empty)
Y
(empty)
Z
(empty)
Tsunami