Weather

What does the letter L indicate on a weather map?

L = Area of lower air pressures. Usually associated with cloudy or stormy weather.

What is lightning?

Lightning is a bright flash of electricity produced by a thunderstorm.

What are the four basic thunderstorm types?

Single cell, Multi-cell cluster, Multi-cell line, and Supercell

Occluded front

Two cold air masses and one warm air mass. The bigger cold pushes the airs up.

Mudslide

a mass of mud and other earthy material that is falling or has fallen down a hillside or other slope.

Tornado

a mobile, destructive vortex of violently rotating winds having the appearance of a funnel-shaped cloud and advancing beneath a large storm system.

Squall lines

a narrow band of high winds and storms associated with a cold front.

Doppler Radar

a radar tracking system using the Doppler effect to determine the location and velocity of a storm, clouds, precipitation, etc.

Avalanche

a rapid flow of snow down a sloping surface.

Hurricane

a storm with a violent wind, in particular a tropical cyclone in the Caribbean. a wind of force 12 on the Beaufort scale (equal to or exceeding 64 knots or 74 mph).

Barometer

A barometer measures atmospheric pressure. A barometer can help to forecast upcoming weather based on the changes it measures in the atmospheric pressure.

Satellite Imagery

A satellite image is an image of the whole or part of the earth taken using artificial satellites. These images have a variety of uses, including: cartography, military intelligence and meteorology. Satellite images can either be visible light images, water vapor images or infrared images.

Flash Flood Statement

A statement by the NWS which provides follow-up information on flash flood watches and warnings.

Anticyclone

Anticyclones is a weather system with high atmospheric pressure at it's center, around which air slowly circulates in a clockwise (northern hemisphere) and counterclockwise (southern hemisphere) direction. Anticyclones are associated with calm fine weather. The air is sinking, not rising, no clouds or rain is being formed.

Super cell storms

Defined as a thunderstorm with a rotating updraft, these storms can produce strong downbursts, large hail, occasional flash floods and weak to violent tornadoes.

Cyclone

A cyclone is a spinning storm that rotates around a low pressure center in which the winds flow counterclockwise in the Northern Hemisphere and clockwise in the Southern Hemisphere.

Derecho

A derecho is a widespread and long-lived windstorm that is associated with a fast-moving band of severe thunderstorms. Derechos are usually not associated with a cold front, but a stationary front.

Flash Flood

A flood which is caused by heavy or excessive rainfall in a short period of time, generally less than 6 hours. Also, at times a dam failure can cause a flash flood, depending on the type of dam and time period during which the break occurs.

Multi-cell cluster storm

A group of cells moving as a single unit, with each cell in a different stage of the thunderstorm life cycle. Multicell storms can produce moderate size hail, flash floods and weak tornadoes.

Gust Fronts

A gust front is the leading edge of cool air rushing down and out from a thunderstorm.

What is a gust front?

A gust front is the leading edge of the downdraft from a thunderstorm. It is usually marked by gusty cool winds, and sometimes blowing dust. You will feel the wind from the gust front before it starts to rain.

What is a High Pressure System?

A high pressure system is a whirling mass of cool, dry air that generally brings fair weather and light winds. When viewed from above, winds spiral out of a high-pressure center in a clockwise rotation in the Northern Hemisphere. A high pressure system is represented as a big, blue H.

Hook Echo

A hook echo is a pendant or hook-shaped weather radar signature as part of some supercell thunderstorms. It is found in the lower portions of a storm as air and precipitation flow into a mesocyclone resulting in a curved feature of reflectivity.

Hygrometer

A hygrometer measures relative humidity.

What is a Low Pressure System?

A low pressure system is a whirling mass of warm, moist air that generally brings stormy weather with strong winds. When viewed from above, winds spiral into a low-pressure center in a counterclockwise rotation in the Northern Hemisphere. A low pressure system is represented as a big, red L.

Macroburst

A microburst is a downdraft (sinking air) in a thunderstorm that is less than 2.5 miles in scale.

Microburst

A microburst is a downdraft (sinking air) in a thunderstorm that is less than 2.5 miles in scale.

Severe Thunderstorm Watch

A severe thunderstorm (damaging winds of 58 miles per hour or more, or 1" hail in diameter or greater) is likely to develop in your area.

Severe Thunderstorm Warning

A severe thunderstorm (damaging winds of 58 miles per hour or more, or hail three-fourths of an inch in diameter or greater) is taking place in your area.

Downdraft

A sudden descent of cool or cold air to the ground, usually with precipitation, and associated with a thunderstorm or shower.

What is a thunderstorm?

A thunderstorm is a storm with lightning and thunder. It's produced by a cumulonimbus cloud, usually producing gusty winds, heavy rain and sometimes hail.

Debris Ball

A tornadic debris signature (TDS), often colloquially referred to as a debris ball, is an area of high reflectivity on weather radar caused by debris lofting into the air, usually associated with a tornado.

Updraft

A warm column of air that rises within a cloud. If the air is sufficiently moist, then the moisture condenses to become a cumulus cloud.

Weather Station

A weather station is a device that collects data related to the weather and environment using many different sensors. Weather stations are also called weather centers, personal weather stations, professional weather stations, home weather station, weather forecaster and forecasters.

Anemometer

An anemometer measures how fast the wind is blowing, or wind speed.

What does the letter H indicate on a weather map?

H = Area of higher air pressures. Usually associated with fair or good weather.

What is hail?

Hail is created when small water droplets are caught in the updraft of a thunderstorm. These water droplets are lifted higher and higher into the sky until they freeze into ice. Once they become heavy, they will start to fall.

What is humidity?

Humidity is the amount of water vapor in the air. Humidity influences environmental factors and calculations like precipitation, fog, dew point and heat index.

Flash Flood Watch

Issued to indicate current or developing hydrologic conditions that are favorable for flash flooding in and close to the watch area, but the occurrence is neither certain or imminent.

Flash Flood Warning

Issued to inform the public, emergency management, and other cooperating agencies that flash flooding is in progress, imminent, or highly likely.

Multi-cell Line storms

Multicell line storms consist of a line of storms with a continuous, well developed gust front at the leading edge of the line. Also known as squall lines, these storms can produce small to moderate size hail, occasional flash floods and weak tornadoes.

What is relative humidity?

Relative humidity is the ratio of water vapor contained in the air compared to the maximum amount of moisture that the air can hold at that specific temperature and pressure.

Semi-Permanent Highs and Lows

Semi-permanent highs and lows are persistent pressure systems that appear over an area during the year and affect how storms and weather systems enter the United States.

What is a dew point?

The dew point is the temperature at which water starts to condense out of a particular air mass. The dew point temperature changes only when the moisture content of the air changes. The higher the dew point, the greater the moisture content is in the air.

What causes a thunderstorm?

You need moisture to form clouds and rain. You need unstable air that is relatively warm and can rise rapidly. Finally, you need lift.

Air Masses

a body of air with horizontally uniform temperature, humidity, and pressure.

NOAA

an agency in the Department of Commerce that maps the oceans and conserves their living resources; predicts changes to the earth's environment; provides weather reports and forecasts floods and hurricanes and other natural disasters related to weather. National Oceanic and Atmospheric Administration.

Debris Flow

are geological phenomena in which water-laden masses of soil and fragmented rock rush down mountainsides, funnel into stream channels, entrain objects in their paths, and form thick, muddy deposits on valley floors.

Downburst

strong winds produced by a downdraft over a horizontal area up to 6 miles (10 kilometers). Downbursts are further subdivided into microbursts and macrobursts.

What are the four Different Types of Cyclones

tropical disturbance, tropical storms, tropical depressions, and hurricanes.