Subj : Wx Terms (O)(1) To : All From : Daryl Stout Date : Wed Aug 16 2017 12:08 am OBS Observation(s) OBSC Obscure Obscuration Any atmospheric phenomenon, except clouds, that restricts vertical visibility (e.g., dust, rain, snow, etc.). Obscuring Phenomena Any atmospheric phenomenon, except clouds, that restricts vertical visibility (e.g., dust, rain, snow, etc.). Observation Well In hydrologic terms, a non-pumping well used for observing the elevation of the water table or piezometric surface. Occluded Front A composite of two fronts, formed as a cold front overtakes a warm or quasi-stationary front. Two types of occlusions can form depending on the relative coldness of the air behind the cold front to the air ahead of the warm or stationary front. A cold occlusion results when the coldest air is behind the cold front and a warm occlusion results when the coldest air is ahead of the warm front. Occluded Mesocyclone A mesocyclone in which air from the rear-flank downdraft has completely enveloped the circulation at low levels, cutting off the inflow of warm unstable low-level air. Oceanography The study of the ocean, embracing and integrating all knowledge pertaining to the ocean's physical boundaries, the chemistry and physics of sea water, and marine biology. OCFNT Occluded Front - a composite of two fronts, formed as a cold front overtakes a warm or quasi-stationary front. Two types of occlusions can form depending on the relative coldness of the air behind the cold front to the air ahead of the warm or stationary front. A cold occlusion results when the coldest air is behind the cold front and a warm occlusion results when the coldest air is ahead of the warm front. OCNL Occasional OEODM The Office of Equal Opportunity and Diversity Management. Provides a dual role. Advises and assists the Assistant Administrator in carrying out the National Weather Service's (NWS) responsibilities relative to Civil Rights laws, Executive Orders, regulatory guidelines, and other nondiscrimination laws within the Federal Government. Advises and assists the Assistant Administrator in carrying out the NWS policy of diversity management by fostering an inclusive workforce, building an environment that respects the individual and offering opportunities for all employees to develop to their full potential. Cultural Diversity is the mixture of differences and similarities each employee brings to the workplace to accomplish the goals of the NWS. Office of Global Programs The Office of Global Programs (OGP) sponsors focused scientific research, within approximately eleven research elements, aimed at understanding climate variability and its predictability. Through studies in these areas, researchers coordinate activities that jointly contribute to improved predictions and assessments of climate variability over a continuum of timescales from season to season, year to year, and over the course of a decade and beyond. Offshore Breeze A wind that blows from the land towards a body of water. Also known as a land breeze. Offshore Flow Occurs when air moves from land to sea, and is usually associated with dry weather. Offshore Waters That portion of the oceans, gulfs, and seas beyond the coastal waters extending to a specified distance from the coastline, to a specified depth contour, or covering an area defined by specific latitude and longitude points. Offshore Waters Forecast (OFF) - A National Weather Service marine forecast product for that portion of the oceans, gulfs, and seas beyond the coastal waters extending to a specified distance from the coastline, to a specified depth contour, or covering an area defined by specific latitude and longitude points. OFSHR Offshore OH Office of Hydrology OHD Overhead Okta Used for the measurement of total cloud cover. One okta of cloud cover is the equivalent of 1/8 of the sky covered with cloud. OLR Outgoing Longwave Radiation Omega A term used to describe vertical motion in the atmosphere. The "omega equation" used in numerical weather models is composed of two terms, the "differential vorticity advection" term and the "thickness advection" term. Put more simply, omega is determined by the amount of spin (or large scale rotation) and warm (or cold) advection present in the atmosphere. On a weather forecast chart, high values of omega (or a strong omega field) relate to upward vertical motion (UVV) in the atmosphere. If this upward vertical motion is strong enough and in a sufficiently moist airmass, precipitation results. Omega High A warm high aloft which has become displaced and is on the polarward side of the jet stream. It frequently occurs in the late winter and early spring in the Northern Hemisphere. The name comes from its resemblance to the Greek letter, Omega, when analyzed on upper air charts. It is an example of a blocking high. Onshore Breeze A wind that blows from a body of water towards the land. Also known as a seabreeze. Onshore Flow Occurs when air moves from sea to land, and is usually associated with increased moisture. Opaque A condition where a material, such as a cloud, blocks the passage of radiant energy, especially light. Opaque sky cover refers to the amount of sky cover that completely hides all that might be above it. OPC Ocean Prediction Center (Formally the Marine Prediction Center. An NCEP center which produces marine forecasts north of 30øN. Open Lakes Forecast (GLF) - A National Weather Service marine forecast product for the U.S. waters within a Great Lake not including the waters covered by an existing Nearshore Waters Forecast (NSH). When the seasonal Nearshore forecast is not issued, the Open Lake forecast includes a forecast of nearshore waters. Operational Products A product that has been fully tested and evaluated and is produced on a regular and ongoing basis. Orifice In hydrologic terms, (1) An opening with closed perimeter, usually sharp edged, and of regular form in a plate, wall, or partition through which water may flow, generally used for the purpose of measurement or control of water. (2) The end of a small tube, such as a Pitot tube, piezometer, etc. ORIG Original Orographic Related to, or caused by, physical geography (such as mountains or sloping terrain). Orographic Lifting Same as Upslope Flow; occurs when air is forced to rise and cool due to terrain features such as hills or mountains. If the cooling is sufficient, water vapor condenses into clouds. Additional cooling results in rain or snow. It can cause extensive cloudiness and increased amounts of precipitation in higher terrain. Orographic Precipitation Precipitation which is caused by hills or mountain ranges deflecting the moisture-laden air masses upward, causing them to cool and precipitate their moisture. Orographic Uplift Same as Orographic Lifting; occurs when air is forced to rise and cool due to terrain features such as hills or mountains. If the cooling is sufficient, water vapor condenses into clouds. Additional cooling results in rain or snow. It can cause extensive cloudiness and increased amounts of precipitation in higher terrain. Orographic Waves A wavelike airflow produced over and in the lee of a mountain barrier. Orphan Anvil Slang for an anvil from a dissipated thunderstorm, below which no other clouds remain. Oscillation A shift in position of various high and low pressure systems that in climate terms is usually defined as an index (i.e., a single numerically-derived number, that represents the distribution of temperature and pressure over a wide ocean area, such as the El Ni¥o-Southern Oscillation, North Atlantic Oscillation, and Pacific Decadal Oscillation). --- þ Synchronet þ The Thunderbolt BBS - wx1der.dyndns.org .