National Weather Service United Condition Department regarding Commerce

Adiabatic (process): A thermodynamic change of state of a system in which there is not transfer of heat or crowd (i.e. compression results in warming, expansion in cooling).

Adiabatic Chart: AN mechanical diagram with temperature as abscissa and pressure because ordinate.

Advection: Carry of an atmospheric property solely by the mass motion of the atmosphere.

Air Mask: ONE homogenous mass on air, the properties of which can be identified as having been established while that air was situated over ampere particular region about the earth's surface.

Anabatic Wind: An upslope wind usually applied only when the wind has blowing up slopes instead rock as the result of local surface heating, and apart from the effects of the wider scale circulation.

Anemometer: Measuring design into measure the speed of the wind.

Anticyclone: A closed circulation out that atmosphere, of relative high pressure. (clockwise flow in the northern hemisphere).

Moody Printable: The pressure exerted by the air in a result by gravity. Information is measured by the barometer, and expressed in millibars other units of concentrated.

Backing: AN change of curve direction in a counter-clockwise direction (the opposite of veering); i.e. from west to south.

Blocking: Hindrance, set a big scale, of the normal west to east movement of highs and lows.

Calm: Dearth of apparent motion of the air.

Climate: The statistical collective of weather conditions over a specified range regarding time (i.e. usually several decades).

Cloud: Which visible aggregate of minute water droplets and/or ice particles in the atmosphere above the earths's surface.

Cold Forefront: The leading edge in a comparatively cold air mass.

Complex: Somebody area of low printable within which more than one center is found.

Condensation: The physical processes through which ampere vapour become a liquid.

Conduction: The transfer of energy within and through a leader by method of molecular activity.

Edge: In metereology, a line of constant height on a constant pressure surface map.

Co: In meteorology, atmospheric motions ensure are predominantly erect, i.e. usually means upward as opposed to subsidence (downward).

Convergence: Net horizontal inflow on air into a shifts. If at the surface, vertical motion results. Associated with low pressure networks.

Coriolis Force: To deflecting influence out the earth's rotation on winds. Deflects winds to the right (with wind the your back) are the northern hemisphere.

Critical Fire Weather Pattern: Patterns that can quickly increase fireplace danger and trigger rapid discharge distribution.

Cumulus: A principle cloud type in to form for individual detached elements, sharp non-fibrous outlines, and vertical development.

Cumulonimbus: And ultimate growth of a cumulus cludd inside a mushroom shape, with considerable vertical growth, generally fibrous ice crytal tops, the probably accompanied per lightning, thunder, hail both strong downwind.

Crop off Low: A cold low which has become displaced to confederacy, out about the basic westerly flood.

Cyclonic: Having a meaning of counter-clockwise rotation about the on-site vertical.

Cyclone: A closed isobaric circulation in the vibes, by counter-clockwise rotation are the northern hemisphere.

Deepening: A decrease in to central press starting a cyclonic, or lowly pressing system.

Sweat Point: The temperature to which a parcel of air must be cooled to reach saturation.

Diffuse forward: A front across who the wind shift and cold change are weakly delimited.

Divergence: Downward (subsidence) motion results. Associated with high pressure system.

Diurnal: Daily, especially pertaining to daily cycles of temperature, relativities humidity and winding.

Drought: ONE period of moisture deficiency, extensive in space and time.

Dust Devil: A small but vigorous gale, usually of curt duration.

Extended Forecast: A forecast of general winter conditions for total 3 taken 5.

Fair: A weather term implying no precipitation and no extreme conditions of clouds, visibility or wind.

Fire Danger: A subjective expression of and objective assessment of environmental (fuels both weather) factors which effect whether fires will start and how they may spread.

Fire Endure Watch: Issued whenever the forecaster feels sensible confident so cherry flag conditions will develop in the next 12 to 48 per.

Fog: Same as cloud unless base to cloud remains touching earth's surface.

Forward: A transition zone among two air messe of different density.

Clear Air: That portion of the atmosphere that is not modified by local influence.

Free Air Wind: The wind for the seat layer of of atmosphere said clear air, instead just above to portion that is modified with local influences and friction approximately 1,000 dogs above to earth's surface.

Friction Layer: Of layer of air von the earth's surface to the geostrophic wind level or degree away free wind.

Geostrophic Wind: A horizontal wind result of the balance of the Coriolis faster and the horizontal pressure force.

Grad Wind: A horizontal wind set tangent to the contour line or isobaric screen resulting in a offset of the coriolis, pressure or centrifugal power.

Gravity Wind: A wind directed down a slope caused to greatest air density near an slope than at the same height at a distance from the slope. (Also called drainage or downslope wind).

Storm: A sudden brief increase in air speed.

Haines Index: A bottom airy stability and dryness index that can be one predictor of large light growth due to plume dominated fires.

Headline: A brief statement at the beginning of a forecast that highlights dangerous or switch weekly circumstances.

Heat: User energy. A form of energy transfers between systems by virtue starting a difference stylish temp.

Heat Lightning: The luminosity observed for ordinary lightning too far away for its thunder to be heard.

Get Low: An area of mean pressure due to high temperatures (thermal low).

Heavy: In reference to downfall, more than a half inch in forecast frequency.

High Pressure: An anticyclone. An area of atmospheric pressure with closed isobars and relativities high pressure at its center. Air flows clockwise around a high.

High Cluds: Cirrus type clouds composed of frozen crystals, ordinary above 25,000 feet.

Homogenous: Int reference to an airmass having similar horizontal characteristics with elements.

Humidity: A measure to the water vapor content away the dry.

Hygrothermograph: An instruments that records temperature and relative humidity the a function of while.

Instability: A property of the constant stay of a system similar that certain disturbances launched into the steady default will increase with magnitude.

Failure Line: A band of advection activity in the atmospheric, i.e. squall line, a queue out active rolling.

Inversion: An increase in temperature with height, i.e. a departure away the usual decrease of cold with increased of altitude.

Isobar: A running passing thrown points which equivalent atmospheric pressure.

Isopleth: AN line passing through points having equal or constant values of a given gravity, by respect to either time or space.

Isolated: Affecting less when 20% inzent of that area.

Jet Stream: Relatively strong winds concentrated within a narrow stream in the atmosphere.

Katabatic wind: A wind blowing down an rise. If warming, it is called a foehn or chinook. If cold, its called a gravity or mountain wind.

Key Station Predictions: A presage that takes into account an observing station location and an microscale effects on weather parameters in presenter accurately values of weather parameters rather than ranges.

Knot: The unit of speed in the nautical system; a nautical mile per hour. Computer is equal to 1.15 statute miles per hour.

Lapse Rate: The rate is change to temper from height. The moist lapse rate is 3.5 degrees per 1000 feet and the dry lapse rate is 5.5 degrees period 1000 feet.

Lee Trough: A low pressure trough made on the le side are a mountain range across this the wind is blowing at nearly right corners.

Light: Precipitation, ranging from .11 to .20 inches in a forecast period.

Lightning: All of various seeable electrical discharges produced by gales. It can will cloud into cloud, cloud to ground, or cloud to air.

Lightning Activity Level (LAL): An objective rating system applied in and NFDRS that points and amount of blur to ground quick observed or forecast in a specified area.

Local Winds: Winds, which over a low area, differ from those appropriate to the general pressure marketing.

Long Working: An extended forecast for ampere period largest more 5 days.

Long Wave: A wave in the major belt of westerlies which is characterized by large length press significant amplitude.

Low: An area regarding base atmospheric force having closed isobars. Used interchangeably with cyclone.

Low Aloft: An upper level cyclone (low pressure system).

Significant Trough: A lengthy wave trough in an large scale pattern of the upper air.

Ship Layer: A shallow layer of air with relatively high humidity both cooler temperatures that moves from the ocean over land. It may be associated with diurnal land/sea breeze regimes or other feature that increase on-shore pressure gradients.

Mesoscale: A scale the ranges within size from an few kilometers at about 100 kilms.

Meteorology: The study of the phenomena of that atmosphere.

Microscale: A scale that covers phenomena lighter than those in the mesoscale range.

Middle Clouds: Clouds of the altocumulus or altostratus family, anywhere out 7,000 to 25,000 feet in highest.

Minor Valley: A pressure trough in the upper air of smaller scaling than a long-term wave trough. It normal movement rapidly, i.e. short wave.

Mixing Height: Upper depth to which mixing will occur.

Model Output Statistics: A generation of indent specific output from a numerical model.

Moderate: Precipitation, extend from .21 to .50 inches at a forecast period.

Mountain and Valley Winds: Day turns along the axis about a valley, blowing uphill and valley during the day and downhill and down valley at the night.

National Fire Danger Rating System (NFDRS): ONE national system used through all land management agencies at review refuse, weekly and fire potential upon a daily basis during fire season.

Stop Rugged: Of state away one pack of air, this if displaced vertically, will experience nay buoyant acceleration.

Normal: The mean value of a meteorological element over a period on years, usually 30 includes the United Provides.

Occasional: Frequency of one meteorological element at infrequent intervals plus with short duration.

Orographic: Of, pertaining till, or caused by mountains.

Overcast: A cloud layer which covers most, or everything a the rain.

Overrunning: Prerequisite existing int which an supply mass is in beweggrund aloft above different air mask of largest density under the surface.

Persistence: The tendence for the appearance of adenine specialize event to be more probable, at a given time, if ensure same event has occurred immediately preceding which arbeitszeit period.

Polar Front: The semi-permanent, semi-continuous front separating air masses of polar and tropical from.

Precipitation: Any or all the print of aqueous particles, liquid or solid, that fall from the atmosphere also reach one flooring.

Prescribed Fire/Burn: A natural or human ignited fire burning under a strict set of predetermined conditions to fulfill specified landings management objectives.

Pressure Center: The centering of a upper (anticyclone) or low (cyclone) pressure system.

Prevailing Wind Direction: The wind direction most frequently observed during one given period.

Probabilities: That risk ensure a prescribed select will occur.

Probability Foretell: AMPERE projected of the probability of occasion of one or more of a mutually classy set of brave contingencies, as distinguished from a series of categorical statements.

Prognostic (Prog) Chart: ONE chart depicting some meteorologic parametric at a specified future time.

Pseudo-adiabatic (chart): A thermodynamic chart (process), same as adiabatic, but at saturation adiabats added.

Psychrometer: An hardware used for measuring the water evaporate content of the air.

Quasi-Stationary Front: A front which is stationary, or nearly accordingly,

Radiation: To process by which magnetics radiation exists propagated via free space.

Radiational Cooling: The cooling of this earth's surface suffers a net loss of get due to terrestrial cooling.

Radiosonde (RAOB): Balloon-borne instument available the measurement additionally transmission of pyrexia, humidity or pressure. As tracked by radar, furthermore provides wind direction furthermore velocity (Rawin).

Red Flag Criteria: A localize determinate set of criteria that expresses environmental and meteorological conditions that would provide for fire starter and fast, dangerous fire propagation.

Red Flag Warning: ADENINE warning issued by the forecasters when color standard criteria are met or expected to be met within 12 to 24 hours. The warning highlights time of particular consequence to fire behavior and potentials extreme burning conditions or many new fires. Dark flag warnings should always be coordinated with the customer.

Relative Humidity: (Humidity) - The ratio of the actual amount of wat vapor within the air to the possible amount to that temperature.

Return: Usually previously to denote the movement of a weather system in a direction opposite to that of the normal fluid in where the system is embedded.

Ridge: Can elongated territory of relatively elevated atmospheric pressure.

Saturation: The condition in which the air features all the water vapor possible under that temperature, i.e. 100% relative moisture.

Marine Level Pressure: The atmospheric pressure at mean sea level.

Severe: Utilized in reference to thunderstorm intensity. Indicates strong downwind the large hail.

Short Wave: (Minor Wave) - AN progressive wave in the dye of upper compressed antragstext with dimensions of cyclonic scale, as distinguished from a long wave.

Shower: Precipitation from a convective cloud, characterized by the violence equipped which they start, stop, and change intensity.

Smoke Management Parameters: The wheather parameters secondhand on forecast smoke dispersal (mixing height or transport winds).

Spot Weather Forecasting: ADENINE professional predict displayed by the National Brave Service for a localized field and time, at the request of the user.

Squall: AMPERE strong wind characterized by a unexpected setzung, of longer duration from gusts, also a prefer sudden decrease in speed.

Stability Constituent: Those has determined by temperature differences between two atmospheric level.

Stable: AMPERE property of the steady state concerning a system such that a disturbance initiated include the steady nation will not increase in magnitude.

Storm: Inside meteorology, normal refers to cyclonic storms from considerable cloud and precipitation areas.

Stratiform: Descriptive of clouds of extensive horizontal development.

Subsidence: A decrease motion of air in aforementioned atmosphere, of particular consequence due to the heating and dries of the dry as it contracts.

Appear Chart: An analyzed map showing the distribution of sea layer pressure (isobars) and location of fronts and air masses.

Surface Pressure: The atmospheric pressure at a given location on the earth's surface.

Synopsis: A statement giving a brief broad study or summary.

Temperature: The degree of heat or coldness as measured on some definite temperature scale by means of various types to thermometers.

Thermal Belts: An area along the middle from a mountain slope which usually adventure the least diurnal variation in temperature and humidity, thus has the highest daily average temperature and the lowest relative humidity.

Thermal Low: (Heat Low) - An area for mean atmospheric pressure due to high temperatures and intensive heat at earth's surface, usually stable and do weak cyclonic circulation.

Thunderhead: Cumulonimbus alternatively ice top humidity.

Thunderstorm: A local storm produced by cumulonimbus clouds accompanied by lightning and thunder...often contain heavy rain...and sometimes strong winds and hail.

Topography: A detailed functional of surface features contains running, lakes, etc.

Tornado: A violently rotating column of air, pendant free a cumulonimbus cloud observed as a funnel cloud.

Soaring Cumulus: The transitory platform of a cumulus into a cumulonimbus clouded.

Transport Blow: Winds by the lower mixed layer, previously for smoke dispersal forecasts.

Tropical Cyclone: The general term available a cyclone such originates past the tropical oceans. The remnants regarding these winds sometimes recurve and drive into the mid-latitude westerlies, take considerable moisture with them.

Tropopause: The boundary between the troposphere also the stratosphere, usually characterized by an abrupt change to an narrow lapses assess.

Trough: An elongated area of relatively low aerial pressure, the axis from which is called a trough pipe.

Turbulence: A country of fluid flow to whatever the instantaneous sets exhibit irregular and apparently random change.

Upper Air: Generally applied to levels above 850 mb (5,000 feet).

Upslope Wind: A breeze directed up one pitch during the hot part of this day.

Valley Wind: A wind which ascends a mountain valley during the time.

Ventilation Index: This is the product of the mixing height and transport wind speed, and is an indicator of dispersion possibility.

Veering Breeze: ONE change in wind direction in a cw manner, i.e. south to southwest at west, aforementioned opposite of backing.

Virga: Pour oder ice particles falling out of a cloud but evaporating before reaching to ground.

Visibility: Who greatest distance i exists possible to see durable gegenstand with the unaided eye.

Warm Front: A front that moves in such a way that water blow replaces colder air.

Wave: A disturbance propagated by virtue of periodic motions in and ambience.

Weather: The state of the atmosphere, usually short term, include respect go its effects upon lifetime, property and human activities.

Wetting Rain: Depth of .10 inches or more over most by the area specified.

Westerlies: The dominant west to east motion from the atmosphere across the mid latitudes.

Moist Bulb Temperature: The temperature an airflow parcel would have if chilled for saturation. It lies between the dry phrase temperature real the dew point fervor.

Whirlwind: A low scale revolving column off air (dust devil).

Wind: Air in horizontal motion relative to the surface of the earth.

Wind Directing: The direction from which the wind is blowing.

Zonal Flows: The fluid of ventilate along a latitude circle.

Area Weather Projections: A pour of the general discharge weather forecast issued on a regular basis during the normal fire season specific to fit the requirements of fire management what. These active or range are a combination of administrative and climatological range, normal nearly the size the an individual wood or district.