(This area often is called positive area.) See also CIN. CAPE is represented on an upper air sounding by the area enclosed between the environmental temperature profile and the path of a rising air parcel, over the layer within which the latter is warmer than the former. However, as with other indices or indicators, there are no threshold values above which severe weather becomes imminent. Observed values in thunderstorm environments often may exceed 1000 joules per kilogram (J/kg), and in extreme cases may exceed 5000 J/kg. CAPE is directly related to the maximum potential vertical speed within an updraft thus, higher values indicate greater potential for severe weather. A measure of the amount of energy available for convection. CAPE Convective Available Potential Energy. Cap Cloud A stationary cloud directly above an isolated mountain peak, with cloud base below the elevation of the peak.
But without a cap, either process (warming/moistening at low levels or cooling aloft) results in a faster release of available instability - often before instability levels become large enough to support severe weather development. Or, air above it can cool, which also increases potential instability. With the cap in place, air below it can continue to warm and/or moisten, thus increasing the amount of potential instability. The cap is an important ingredient in most severe thunderstorm episodes, as it serves to separate warm, moist air below and cooler, drier air above. However, if the cap is removed or weakened, then explosive thunderstorm development can occur. As such, the cap often prevents or delays thunderstorm development even in the presence of extreme instability. Air parcels rising into this layer become cooler than the surrounding air, which inhibits their ability to rise further and produce thunderstorms. Cap (also called "Lid") A layer of relatively warm air aloft, usually several thousand feet above the ground, which suppresses or delays the development of thunderstorms. Canyon Wind A foehn wind that is channeled through a canyon as it descends the lee side of a mountain barrier. Calm A weather condition when no air motion (wind) is detected. Calibration In hydrologic terms, the process of using historical data to estimate parameters in a hydrologic forecast technique such as SACSMA, routings, and unit hydrographs.
in an overrunning scenario.Įffects on the weather may include cold temperatures, freezing precipitation, and extensive cloud cover CADAS Centralized Automated Data Acquisition System - a system of two minicomputers in NWSH.
Cold Air Damming often implies that the trapped cold air mass is influencing the dynamics of the overlying air mass, e.g. Often, this cold air is entrenched on the east side of mountainous terrain. The phenomenon in which a low-level cold air mass is trapped topographically. CAA Cold Air Advection CAD Cold Air Damming. Central C AMS Continental Air Mass CA Cloud-to-Air lightning. Press enter or select the go button to submit requestĢ.
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