Subj : Wx Terms (S)(10) To : All From : Daryl Stout Date : Wed Sep 20 2017 12:05 am Sunspot Group Classification A: A small single unipolar sunspot or very small group of spots without penumbra. B: Bipolar sunspot group with no penumbra. C: An elongated bipolar sunspot group. One sunspot must have penumbra. D: An elongated bipolar sunspot group with penumbra on both ends of the group. E: An elongated bipolar sunspot group with penumbra on both ends. Longitudinal extent of penumbra exceeds 10 deg. but not 15 deg. F: An elongated bipolar sunspot group with penumbra on both ends. Longitudinal extent of penumbra exceeds 15 deg. H: A unipolar sunspot group with penumbra. Sunspot Number In solar-terrestrial terms, a daily index of sunspot activity (R), defined as R = k (10 g + s) where S = number of individual spots, g = number of sunspot groups, and k is an observatory factor. Super Typhoon Typhoon having maximum sustained winds of 130 knots (150 mph) or greater. Supercell Short reference to Supercell Thunderstorm; potentially the most dangerous of the convective storm types. Storms possessing this structure have been observed to generate the vast majority of long-lived strong and violent (F2-F5) tornadoes, as well as downburst damage and large hail. It is defined as a thunderstorm consisting of one quasi-steady to rotating updraft which may exist for several hours. Supercell Thunderstorm Potentially the most dangerous of the convective storm types. Storms possessing this structure have been observed to generate the vast majority of long-lived strong and violent (F2-F5) tornadoes, as well as downburst damage and large hail. It is defined as a thunderstorm consisting of one quasi-steady to rotating updraft which may exist for several hours. Supercells usually move to the right of the mean wind. These are called "Right Movers" and they are favored with veering winds. Occasionally, these thunderstorms will move to the left of the mean wind. These thunderstorms are called "Left Movers". These supercells typically don't last as long as their "Right Mover" cousins and they usually only produce large hail (greater than 3/4 inch in diameter) and severe wind gusts in the excess of 58 miles an hour. Left Movers are favored when you have backing winds. Radar will observe essentially one long-lived cell, but small perturbations to the cell structure may be evident. The stronger the updraft, the better the chance that the supercell will produce severe (hail greater than 3/4 inch in diameter, wind gusts greater than 58 miles an hour, and possibly a tornado) weather. Severe supercell development is most likely in an environment possessing great buoyancy (CAPE) and large vertical wind shear. A Bulk Richardson Number of between 15 and 35 favor supercell development. Typically, the hodograph will look like a horse shoe. This is due to the wind speed increasing rapidly with height and the wind direction either veering or backing rapidly with height. Supercool To cool a liquid below its freezing point without solidification or crystallization. Supercooled Liquid Water In the atmosphere, liquid water can survive at temperatures colder than 0 degrees Celsius; many vigorous storms contain large amounts of supercooled liquid water at cold temperatures. Important in the formation of graupel and hail. Superrefraction Bending of the radar beam in the vertical which is greater than sub-standard refractive conditions. This causes the beam to be lower than indicated, and often results in extensive ground clutter as well as an overestimation of cloud top heights. Surcharge Capacity In hydrologic terms, the volume of a reservoir between the maximum water surface elevation for which the dam is designed and the crest of an uncontrolled spillway, or the normal full-pool elevation of the reservoir with the crest gates in the normal closed position. Surf Zone Area of water between the high tide level on the beach and the seaward side of the breaking waves. Surf Zone Forecast (SRF) - 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. Surface Energy Budget The energy or heat budget at the earth's surface, considered in terms of the fluxes through a plane at the earth-atmosphere interface. The energy budget includes radiative, sensible, latent and ground heat fluxes. Surface impoundment In hydrologic terms, an indented area in the land's surface, such as a pit, pond, or lagoon. Surface Runoff In hydrologic terms, the runoff that travels overland to the stream channel. Rain that falls on the stream channel is often lumped with this quantity. Surface Water Water that flows in streams and rivers and in natural lakes, in wetlands, and in reservoirs constructed by humans. Surface Weather Chart An analyzed synoptic chart of surface weather observations. A surface chart shows the distribution of sea-level pressure (therefore, the position of highs, lows, ridges and troughs) and the location and nature of fronts and air masses. Often added to this are symbols for occurring weather phenomena. Although the pressure is referred to mean sea level, all other elements on this chart are presented as they occur at the surface point of observation. Surface-based Convection Convection occurring within a surface-based layer, i.e., a layer in which the lowest portion is based at or very near the earth's surface. Compare with elevated convection. Surge In solar-terrestrial terms, a jet of material from active regions that reaches coronal heights and then either fades or returns into the chromosphere along the trajectory of ascent. Sustained Overdraft In hydrologic terms, long-term withdrawal from the aquifer of more water than is being recharged. Sustained Wind Wind speed determined by averaging observed values over a two-minute period. SVR 1. Severe 2. Abbreviation for Severe Thunderstorm Warning SVRL Several SW 1. Southwest 2. Snow Showers SWD On a buoy report, Swell Direction is the compass direction from which the swell wave are coming from. SWE Snow Water Equivalent (the amount of water content in a snowpack or snowfall). SWEAT Severe Weather ThrEAT index; a stability index developed by the Air Force which incorporates instability, wind shear, and wind speeds as follows: SWEAT=(12 Td 850 ) + (20 [TT-49]) +( 2 f 850) + f 500 + (125 [s+0.2]) where Td 850 is the dew point temperature at 850 mb, TT is the total-totals index, f 850 is the 850-mb wind speed (in knots), f 500 is the 500-mb wind speed (in knots), and s is the sine of the angle between the wind directions at 500 mb and 850 mb (thus representing the directional shear in this layer). SWEAT values of about 250-300 or more indicate a greater potential for severe weather, but as with all stability indices, there are no magic numbers. The SWEAT index has the advantage (and disadvantage) of using only mandatory-level data (i.e., 500 mb and 850 mb), but has fallen into relative disuse with the advent of more detailed upper air sounding analysis programs. Swell Wind-generated waves that have travelled out of their generating area. Swells characteristically exhibit smoother, more regular and uniform crests and a longer period than wind waves. --- þ Synchronet þ The Thunderbolt BBS - wx1der.dyndns.org .