Subj : Wx Terms (A)(3)
To : All
From : Daryl Stout
Date : Sun Sep 03 2017 10:39 am
Air Toxin
Toxic air pollutant.
Air Transportable Mobile Unit
A modularized transportable unit containing communications and
observational equipment necessary to support a meteorologist preparing
on-site forecasts at a wildfire or other incident.
Airborne Snow Survey Program
In hydrologic terms, Center (NOHRSC) program that makes airborne snow
water equivalent and soil moisture measurements over large areas of the
country that are subject to severe and chronic snowmelt flooding.
AIRMET
Airman's Meteorological advisory (WA)
AIV
Aviation Impact Variables
Alaska Current
A North Pacific Ocean current flowing counterclockwise in the Gulf of
Alaska. It is the northward flowing (warm) division of the Aleutian
Current.
Albedo
Reflectivity; the fraction of radiation striking a surface that is
reflected by that surface.
Alberta Clipper
A fast moving low pressure system that moves southeast out of Canadian
Province of Alberta (southwest Canada) through the Plains, Midwest, and
Great Lakes region usually during the winter. This low pressure area is
usually accompanied by light snow, strong winds, and colder temperatures.
Another variation of the same system is called a "Saskatchewan Screamer".
ALERT
Automated Local Event Reporting in Real Time. Network of automatic
raingauges that transmit via VHF radio link when precipitation occurs.
Some sites are also equipped with other sensors such as temperature,
wind, pressure, river stage or tide level.
Alert Stage
The stage which, when reached by a rising stream, represents the level
where appropriate officials (e.g., county sheriff, civil defense
officials, or bypass gate operators) are notified of the threat of
possible flooding. (Used if different from action stage, and at the
discretion of the WFO or river forecast center [RFC].) The term
"alert stage" is to be used instead of warning stage. Monitor stage or
caution stage may be used instead of alert stage in some parts of the
country.
Aleutian Current
An eastward flowing North Pacific Ocean current which lies north of the
North Pacific Current.
Aleutian Low
A semi-permanent, subpolar area of low pressure located in the Gulf of
Alaska near the Aleutian Islands. It is a generating area for storms
and migratory lows often reach maximum instensity in this area. It is
most active during the late fall to late spring. During the summer, it
is weaker, retreating towards the North Pole and becoming almost
nonexistent. During this time, the North Pacific High pressure system
dominates.
ALF
Aloft
ALG
Along
Algorithm
A computer program (or set of programs) which is designed to
systematically solve a certain kind of problem. WSR-88D radars (NEXRAD)
employ algorithms to analyze radar data and automatically determine
storm motion, probability of hail, VIL, accumulated rainfall, and
several other parameters.
Alluvium
Sediments deposited by erosional processes, usually by streams.
Along-slope Wind System
A closed, thermally driven diurnal mountain wind circulation whose lower
branch blows up or down the sloping sidewalls of a valley or mountain.
The upper branch blows in the opposite direction, thereby closing the
circulation.
ALQDS
All Quadrants
ALTHO
although
Altimeter
An instrument that indicates the altitude of an object above a fixed
level. Pressure altimeters use an aneroid barometer with a scale graduated
in altitude instead of pressure.
Altimeter Setting
A correction of the station pressure to sea level used by aviation. This
correction takes into account the standard variation of pressure with
height and the influence of temperature variation with height on the
pressure. The temperatures used correspond to the standard atmosphere
temperatures between the surface and sea level.
Altocumulus
A cloud of a class characterized by globular masses or rolls in layers or
patches, the individual elements being larger and darker than those of
cirrocumulus and smaller than those of stratocumulus. These clouds are of
medium altitude, about 8000-20,000 ft (2400-6100 m).
Altostratus
A cloud of a class characterized by a generally uniform gray sheet or
layer, lighter in color than nimbostratus and darker than cirrostratus.
These clouds are of medium altitude, about 8000 to 20,000 ft
(2400-6100 m).
Ambient
Of the surrounding area or environment.
AMD
Amend
AMOS
Automatic Meteorological Observing System
Amplifier
A device used to increase the strength of an analog signal
Amplitude
The maximum magnitude of a quantity. Often used to refer to the maximum
height of a wave.
AMS
1. Air Mass - a body of air covering a relatively wide area and
exhibiting horizontally uniform properties.
2. American Meteorological Society
AMT
Amount
AMVER
Automated Mutual Assistance Vessel Rescue System. A system operated by
the U.S. Coast Guard which computes the nearest available rescue vessels
for vessels in distress using vessel track and position reports supplied
by participating vessels.
AMVER/SEAS
A software program created by the National Weather Service intended to
efficiently generate AMVER and VOS reports as part of a cooperative
effort.
Anabranch
A diverging branch of a river which re-enters the main stream.
Analog
1. Class of measuring devices in which the output varies continuously as
a function of the input (non-digital).
2. A historical instance of a given meteorological scenario or feature
that is used for comparison with another scenario or feature. For example,
a long-range forecaster predicting conditions for the upcoming winter may
make comparisons to analog seasons in which meteorological factors were
similar to those of the upcoming season.
Analog Signal
A signal, such as voice, that varies in a continuous manner.
ANBURS
Alphanumeric Backup Replacement System
Anchor Ice
In hydrologic terms, submerged frazil ice attached or anchored to the
river bottom, irrespective of its formation.
Anchor Ice Dam
An accumulation of anchor ice which acts as a dam and raises the water
level.
Anemometer
An instrument used for measuring the speed of the wind.
Aneroid Barometer
An instrument for measuring atmospheric pressure in which a needle,
attached to the top of an evacuated box, is deflected as changes in
atmospheric pressure cause the top of the box to bend in or out.
Angels
Radar echoes caused by birds, insects, and localized refractive index
discontinuities.
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