Subj : Wx Terms (S)(5) To : All From : Daryl Stout Date : Thu Jul 20 2017 12:05 am Small Craft Advisory for Winds (SCAW): An advisory issued by coastal and Great Lakes Weather Forecast Offices (WFO). This advisory may be included in the Coastal Waters Forecast or Nearshore Marine Forecast products. This advisory may be issued when wave heights are lower than small craft advisory criteria, yet wind speeds are potentially hazardous. Thresholds governing the issuance of small craft advisories are specific to geographic areas. Eastern (ME..SC, Lake Erie, Lake Ontario) - Sustained winds ranging between 25 and 33 knots (except 20 to 25 knots, lower threshold area dependent, to 33 knots for harbors, bays, etc.) Central (MN..OH) - Sustained winds or frequent gusts (on the Great Lakes) between 22 and 33 knots inclusive. Southern (GA..TX and Caribbean) - Sustained winds of 20 to 33 knots that are expected for more than 2 hours. Western (WA..CA) - Sustained winds of 21 to 33 knots. Alaska (AK) - Sustained winds or frequent gusts of 23 to 33 knots. Pacific (HI, Guam, etc) - Sustained winds 25 knots or greater; except in Guam where it is sustained winds of 22 to 33 knots. Small Craft Should Exercise Caution Precautionary statement issued to alert mariners with small, weather sensitive boats. Small Hail Technically used to refer to snow pellets or graupel. Small Stream Flooding In hydrologic terms, flooding of small creeks, streams, or runs. Smog Originally smog meant a mixture of smoke and fog. Now, it means air that has restricted visibility due to pollution or pollution formed in the presence of sunlight--photochemical smog. Smoke (abbrev. K) Smoke in various concentrations can cause significant problems for people with respiratory ailments. It becomes a more universal hazard when visibilities are reduced to 1/2 mile or less. Smoke Dispersal Describes the ability of the atmosphere to ventilate smoke. Depends on the stability and winds in the lower layers of the atmosphere, i.e., a combination of mixing heights and transport winds. Smoke Management The use of meteorology, fuel moisture, fuel loading, fire suppression and burn techniques to keep smoke impacts from prescribed fires within acceptable limits. Smoothed Sunspot Number An average of 13 monthly RI numbers, centered on the month of concern. SMW (Special Marine Warning) - A warning product issued for potentially hazardous weather conditions usually of short duration (up to 2 hours) producing sustained marine thunderstorm winds or associated gusts of 34 knots or greater; and/or hail 3/4 inch or more in diameter; and/or waterspouts affecting areas included in a Coastal Waters Forecast, a Nearshore Marine Forecast, or an Great Lakes Open Lakes Forecast that is not adequately covered by existing marine warnings. Also used for short duration mesoscale events such as a strong cold front, gravity wave, squall line, etc., lasting less than 2 hours and producing winds or gusts of 34 knots or greater. SN snow Snotel SNOw TELemetry - An automated network of snowpack data collection sites. The Natural Resources Conservation Service (NRCS), formerly the Soil Conservation Service (SCS), has operated the Federal-State-Private Cooperative Snow Survey Program in the western United States since 1935. A standard SNOTEL site consists of a snow pillow, a storage type precipitation gage, air temperature sensor and a small shelter for housing electronics. Snow Precipitation in the form of ice crystals, mainly of intricately branched, hexagonal form and often agglomerated into snowflakes, formed directly from the freezing [deposition] of the water vapor in the air. Snow Accumulation and Ablation Model In hydrologic terms, a model which simulates snow pack accumulation, heat exchange at the air-snow interface, areal extent of snow cover, heat storage within the snow pack, liquid water retention, and transmission and heat exchange at the ground-snow interface. Snow Advisory This product is issued by the National Weather Service when a low pressure system produces snow that may cause significant inconveniences, but do not meet warning criteria and if caution is not exercised could lead to life threatening situations. The advisory criteria varies from area to area. If the forecaster feels that it is warranted, he or she can issued it for amounts less than the minimum criteria. For example, it may be issued for the first snow of the season or when snow has not fallen in long while. Snow Core A sample of either freshly fallen snow, or the combined old and new snow on the ground. This is obtained by pushing a cylinder down through the snow layer and extracting it. Snow Cornice A mass of snow or ice projecting over a mountain ridge. Snow Density The mass of snow per unit volume which is equal to the water content of the snow divided by its depth. Snow Depth The combined total depth of both the old and new snow on the ground. Snow Flurries Snow flurries are an intermittent light snowfall of short duration (generally light snow showers) with no measurable accumulation (trace category). Snow Grains Precipitation consisting of white, opaque ice particles usually less than 1 mm in diameter. Snow Pack Same as Snowcover; the combined layers of snow and ice on the ground at any one time. Snow Pellets Precipitation, usually of brief duration, consisting of crisp, white, opaque ice particles, round or conical in shape and about 2 to 5 mm in diameter. Same as graupel or small hail. Snow Pillow 1) A window of snow deposited in the immediate lee of a snow fence or ridge. or 2) In hydrologic terms, an instrument used to measure snow water equivalents. Snow pillows typically have flat stainless steel surface areas. The pillow below this flat surface is filled with antifreeze solution and the pressure in the pillow is related to the water-equivalent depth of the snow on the platform. One great advantage of snow pillows over a snow survey is the frequency of observations, which can be as high as twice per day. Snow Shower A snow shower is a short duration of moderate snowfall. Some accumulation is possible. Snow Squall A snow squall is an intense, but limited duration, period of moderate to heavy snowfall, accompanied by strong, gusty surface winds and possibly lightning (generally moderate to heavy snow showers). Snow accumulation may be significant. Snow Stake A 1-3/4 inch square, semi-permanent stake, marked in inch increments to measure snow depth. Snow Stick A portable rod used to measure snow depth. Snow Water Equivalent The water content obtained from melting accumulated snow. Snowboard A flat, solid, white material, such as painted plywood, approximately two feet square, which is laid on the ground, or snow surface by weather observers to obtain more accurate measurements of snowfall and water content. Snowcover Also known as Snow Pack; the combined layers of snow and ice on the ground at any one time. Snowflake An agglomeration of snow crystals falling as a unit. Snowmelt Flooding In hydrologic terms, flooding caused primarily by the melting of snow. Snowpack The total snow and ice on the ground, including both the new snow and the previous snow and ice which has not melted. SNR Signal-to-Noise Ratio SNW Snowfall SNWFL Snowfall --- þ Synchronet þ The Thunderbolt BBS - wx1der.dyndns.org .