Subj : Wx Terms (B)(2) To : All From : Daryl Stout Date : Sun Sep 03 2017 10:39 am Base Station In hydrologic terms, a computer which accepts radio signals from ALERT gaging sites, decodes the data, places the data in a database, and makes the data available to other users. Base Width In hydrologic terms, the time duration of a unit hydrograph. Baseflow In hydrologic terms, streamflow which results from precipitation that infiltrates into the soil and eventually moves through the soil to the stream channel. This is also referred to as ground water flow, or dry-weather flow. Basin An area having a common outlet for its surface runoff. Also called a "Drainage Basin." Basin Boundary The topographic dividing line around the perimeter of a basin, beyond which overland flow (i.e.; runoff) drains away into another basin. Basin Lag In hydrologic terms, the time it takes from the centroid of rainfall for the hydrograph to peak. Basin Recharge In hydrologic terms, rainfall that adds to the residual moisture of the basin in order to help recharge the water deficit. i.e; water absorbed into the soil that does not take the form of direct runoff. Bathymetry The science of measuring depths of the oceans, lakes, seas, etc. BCKG Backing- A counterclockwise shift in wind direction (for example, south winds shifting to the east). BCM Become BCMNG Becoming BD Blowing Dust Beach Erosion The movement of beach materials by some combination of high waves, currents and tides, or wind. Bear's Cage [Slang], a region of storm-scale rotation, in a thunderstorm, which is wrapped in heavy precipitation. This area often coincides with a radar hook echo and/or mesocyclone, especially one associated with an HP storm. The term reflects the danger involved in observing such an area visually, which must be done at close range in low visibility. Beaufort Scale The Beaufort wind scale is a system used to estimate and report wind speeds when no measuring apparatus is available. It was invented in the early 19th Century by Admiral Sir Francis Beaufort of the British Navy as a way to interpret winds from conditions at sea. Since that time, the scale has been modernized for effects on land. Beaufort Force 0 - Wind less than 1 kt, Calm, Sea surface smooth and mirror-like. Smoke rises vertically. Beaufort Force 1 - Wind 1-3 kt, Light Air, Scaly ripples, no foam crests. Smoke drift indicates wind direction, still wind vanes. Beaufort Force 2 - Wind 4-6 kt, Light Breeze, Small wavelets, crests glassy, no breaking waves. Wind felt on face, leaves rustle, vanes begin to move. Beaufort Force 3 - Wind 7-10 kt, Gentle Breeze, Large wavelets, crests begin to break, scattered whitecaps. Leaves and small twigs constantly moving, light flags extended. Beaufort Force 4 - Winds 11-16 kt, Moderate Breeze, Small waves 1-4 ft. becoming longer, numerous whitecaps. Dust, leaves, and loose paper lifted, small tree branches move. Beaufort Force 5 - Winds 17-21 kt, Fresh Breeze, Moderate waves 4-8 ft taking longer form, many whitecaps, some spray. Small trees in leaf begin to sway. Beaufort Force 6 - Winds 22-27 kt, Strong Breeze, Larger waves 8-13 ft, whitecaps common, more spray. Larger tree branches moving, whistling in wires. Beaufort Force 7 - Winds 28-33 kt, Near Gale, Sea heaps up, waves 13-20 ft, white foam streaks off breakers. Whole trees moving, resistance felt walking against wind. Beaufort Force 8 - Winds 34-40 kt Gale, Moderately high (13-20 ft) waves of greater length, edges of crests begin to break into spindrift, foam blown in streaks. Whole trees in motion, resistance felt walking against wind. Beaufort Force 9 - Winds 41-47 kt, Strong Gale, High waves (20 ft), sea begins to roll, dense streaks of foam, spray may reduce visibility. Slight structural damage occurs, slate blows off roofs. Beaufort Force 10 - Winds 48-55 kt, Storm, Very high waves (20-30 ft) with overhanging crests, sea white densely blown foam, heavy rolling, lowered visibility. Seldom experienced on land, trees broken or uprooted, "considerable structural damage". Beaufort Force 11 - Winds 56-63 kt, Violent Storm, Exceptionally high (30-45 ft) waves, foam patches cover sea, visibility more reduced. Beaufort Force 12 -Winds 64+ kt, Hurricane, Air filled with foam, waves over 45 ft, sea completely white with driving spray, visibility greatly reduced. Beaver('s) Tail [Slang], a particular type of inflow band with a relatively broad, flat appearance suggestive of a beaver's tail. It is attached to a supercell's general updraft and is oriented roughly parallel to the pseudo-warm front, i.e., usually east to west or southeast to northwest. As with any inflow band, cloud elements move toward the updraft, i.e., toward the west or northwest. Its size and shape change as the strength of the inflow changes. See also inflow stinger. Bed Load In hydrologic terms, sand, silt, gravel, or soil and rock detritus carried by a stream on or immediately above its bed. The particles of this material have a density or grain size such as to preclude movement far above or for a long distance out of contact with the stream bed under natural conditions of flow. Beginning of Freezup In hydrologic terms, date on which ice forming a stable winter ice cover is first observed on the water surface. Beginning of the Breakup In hydrologic terms, date of definite breaking, movement, or melting of ice cover or significant rise of water level. Benchmark (Abbrev. BM) - In hydrologic terms, a permanent point whose known elevation is tied to a national network. These points are created to serve as a point of reference. Benchmarks have generally been established by the USGS, but may have been established by other Federal or local agencies. Benchmarks can be found on USGS maps. Bergeron Process The process by which ice crystals in a cloud grow at the expense of supercooled liquid water droplets. Bergy Bit A piece of ice which has broken away from an iceberg, extending 1-5 meters above the sea surface and 100-300 square meters in area. Can also be the remains of a melting iceberg. Bermuda High A semi-permanent, subtropical area of high pressure in the North Atlantic Ocean off the East Coast of North America that migrates east and west with varying central pressure. Depending on the season, it has different names. When it is displaced westward, during the Northern Hemispheric summer and fall, the center is located in the western North Atlantic, near Bermuda. In the winter and early spring, it is primarily centered near the Azores in the eastern part of the North Atlantic. Also known as Azores High. Best Track A subjectively-smoothed representation of a tropical cyclone's location and intensity over its lifetime. The best track contains the cyclone's latitude, longitude, maximum sustained surface winds, and minimum sea-level pressure at 6-hourly intervals. Best track positions and intensities, which are based on a post-storm assessment of all available data, may differ from values contained in storm advisories. They also generally will not reflect the erratic motion implied by connecting individual center fix positions. BFR Before BGN Begin BHND Behind Billow Cloud A cloud consisting of broad parallel bands oriented perpendicular to the wind. BINOVC Breaks in Overcast --- þ Synchronet þ The Thunderbolt BBS - wx1der.dyndns.org .