Subj : Wx Terms (S)(7) To : All From : Daryl Stout Date : Thu Jul 20 2017 12:05 am Sphere Calibration Reflectivity calibration of a radar by pointing the dish at a metal sphere of (theoretically) known reflectivity. The sphere is often tethered to a balloon. Spillway In hydrologic terms, a structure over or through which excess or flood flows are discharged. If the flow is controlled by gates, it is a controlled spillway, if the elevation of the spillway crest is the only control, it is an uncontrolled spillway. Spillway Crest In hydrologic terms, the elevation of the highest point of a spillway. Spin-Up Slang for a small-scale vortex initiation, such as what may be seen when a gustnado, landspout, or suction vortex forms. SPKL Sprinkle Split Flow A flow pattern high in the atmosphere characterized by diverging winds. Storms moving along in this type of flow pattern usually weaken. Splitting Storm A thunderstorm which splits into two storms which follow diverging paths (a left mover and a right mover). The left mover typically moves faster than the original storm, the right mover, slower. Of the two, the left mover is most likely to weaken and dissipate (but on rare occasions can become a very severe anticyclonic-rotating storm), while the right mover is the one most likely to reach supercell status. SPLNS Southern Plains Sporadic E In solar-terrestrial terms, a phenomenon occurring in the E region of the ionosphere, which significantly affects HF radiowave propagation. Sporadic E can occur during daytime or nighttime and it varies markedly with latitude. SPOTNIL In solar-terrestrial terms, a spotless disk. Spotting Outbreak of secondary fires as firebrands or other burning materials are carried ahead of the main fire line by winds. Spray An ensemble of water droplets torn by the wind from an extensive body of water, generally from the crests of waves, and carried up into the air in such quantities that it reduces the horizontal visibility. SPRD Spread Spring 1. The season of the year comprising the transition period from winter to summer occurring when the sun is approaching the summer solstice. In the Northern Hemisphere, spring customarily includes the months of March, April and May. 2. In hydrologic terms, an issue of water from the earth; a natural fountain; a source of a reservoir of water. Spring Tide A tide higher than normal which occurs around the time of the new and full moon. SPS Severe Weather Potential Statement SQLN Squall Line Squall 1. A strong wind characterized by a sudden onset, a duration of the order of minutes, and then a rather sudden decrease in speed. In U.S. observational practice, a squall is reported only if a wind speed of 16 knots or higher is sustained for at least two minutes (thereby distinguishing it from a gust). 2. In nautical use, a severe local storm considered as a whole, that is, winds and cloud mass and (if any) precipitation, thunder and lightning. Squall Line A line of active thunderstorms, either continuous or with breaks, including contiguous precipitation areas resulting from the existence of the thunderstorms. SRF (Surf Zone Forecast) - A National Weather Service routine or event driven forecast product geared toward non-boating marine users issued for an area extending from the area of water between the high tide level on the beach and the seaward side of the breaking waves. SRH Storm-Relative Helicity SRN Southern SS Sandstorm SSHS Saffir/Simpson Hurricane Scale SST Sea Surface Temperature ST Stratus St Lawrence Freeze-Up Outlook A National Weather Service forecast product to keep mariners informed of the projected freeze-up date of ice the St. Lawrence River. St. Elmo's Fire The glow on a masthead produced by an extreme buildup of electrical charge. Unprotected mariners should immediately move to shelter when this phenomena occurs. Lightning may strike the mast within five minutes after it begins to glow. Stability The degree of resistance of a layer of air to vertical motion. Stability Index The overall stability or instability of a sounding is sometimes conveniently expressed in the form of a single numerical value. Used alone, it can be quite misleading, and at times, is apt to be worthless. The greatest value of an index lies in alerting the forecaster to those soundings which should be examined more closely. Stable An atmospheric state with warm air above cold air which inhibits the vertical movement of air. Stable Boundary Layer The stably-stratified layer that forms at the surface and grows upward, usually at night or in winter, as heat is extracted from the atmosphere's base in response to longwave radiative heat loss from the ground. Stable boundary layers can also form when warm air is advected over a cold surface or over melting ice. Stable Core Post-sunrise, elevated remnant of the temperature inversion that has built up overnight within a valley. Staccato Lightning A Cloud to Ground (CG) lightning discharge which appears as a single very bright, short-duration stroke, often with considerable branching. Stage The level of the water surface of a river or stream above an established datum at a given location. Stair Stepping In hydrologic terms, the process of continually updating river forecasts for the purpose of incorporating the effects rain that has fallen since the previous forecast was prepared. Standard Atmosphere A hypothetical vertical distribution of atmospheric temperature, pressure, and density that, by international agreement, is taken to be representative of the atmosphere for purposes of pressure altimeter calibrations, aircraft performance calculations, aircraft and missile design, ballistic tables, etc. Standard Synoptic Times The times of 0000, 0600, 1200, and 1800 UTC. Also known as the main synoptic times. State Forecast Product This National Weather Service product is intended to give a good general picture of what weather may be expected in the state during the next 5 days. The first 2 days of the forecast is much more specific than the last 3 days. In comparison with the Zone Forecast Product, this product will be much more general. State Weather Roundup This is a National Weather Service tabular product which provides routine hourly observations within the state through the National Weather Wire Service (NWWS). It gives the current weather condition in one word (cloudy, rain, snow, fog, etc.), the temperature and dew point in Fahrenheit, the relative humidity, wind speed and direction, and finally additional information (wind chill, heat index, a secondary weather condition). These reports are broken up regionally. When the complementary satellite product is not available, reports from unaugmented ASOS stations will report "fair" in the sky/weather column when there are few or no clouds (i.e., scattered or less) below 12,000 feet with no significant weather and/or obstructions to visibility. Station ID Five-digit WMO Station Identifier used by the Buoy Data Center since 1976. ID's can be reassigned to future deployments within the same 1 degree square. --- þ Synchronet þ The Thunderbolt BBS - wx1der.dyndns.org .