Fog is the visible aggregate of minute water droplets suspended in the atmosphere near the surface. Over the marine environment the term fog refers to visibility greater than or equal to 1/2 NM and less than 3 NM. Sea Surface Temperature (fahrenheit or celsius)ĭirection: Wind barbs point in the direction the wind is coming from. 0.7 mb pressure decrease with steady pressure fall Thunderstorm ( additional present weather symobls)ĭew point temperature (fahrenheit or celsius) Indicates an expected rapid intensification of a cyclone with surface pressure expected to fall by at least 24 millibars (mb) within 24 hours.Ī sudden wind increase characterized by a duration of minutes and followed by a sudden decrease in winds. For example, a surface analysis may depict a 24-hour position of a new low pressure center with an "X" at the 24-hour position followed by the term "NEW", the date and time in UTC which indicates the low is expected to form by 24 hours. The term "NEW" may be used in lieu of a forecast track position of a low pressure center when the center is expected to form by a specific time. Also, defined as a cyclone.Īn area of higher pressure identified with a clockwise circulation in the northern hemisphere and a counterclockwise circulation in the southern hemisphere. Tropical cyclones occasionally evolve into extratropical lows losing tropical characteristics and become associated with frontal discontinuity.Īn area of low pressure identified with counterclockwise circulation in the northern hemisphere and clockwise in the southern hemisphere. High pressure with a number such as 25 means 1025 mb.Ī low pressure center which refers to a migratory frontal cyclone of center and higher latitudes. Low pressure with a number such as 99 means 999 mb and with 03 means 1003 mb. Low & High Pressure Systems and Miscellaneous Key Terms Ahead of a typical warm front in the northern hemisphere, winds are from the southeast and behind the front winds will shift to the southwest. The gradients of temperature and moisture are maximized in the frontal zone. The leading edge of a relatively warmer surface air mass which separates two distinctly different air masses. These processes lead to the dissipation of the front in which there is no gradient in temperature and moisture.Īn elongated area of relatively high pressure that is typically associated with a anti-cyclonic wind shift.Ī front that has not moved appreciably from its previous analyzed position.Īn elongated area of relatively low pressure that is typically associated with a cyclonic wind shift. When a warm front overtakes a cold front or quasi-stationary front the process is termed a warm front occlusion. The union of two fronts, formed as a cold front overtakes a warm front or quasi-stationary front refers to a cold front occlusion. The weakening or dissipation of a front occurs when two adjacent air masses lose contrasting properties such as the density and temperature. It occurs most frequently over continental land areas such as over the Eastern US when the air mass moves out over the ocean. The formation of a front occurs when two adjacent air masses with different densities and temperatures meet and strengthen the discontinuity between the air masses. In the northern hemisphere winds ahead of the front will be southwest and shift into the northwest with frontal passage. The leading edge of a relatively colder air mass which separates two air masses in which the gradients of temperature and moisture are maximized. Q-STNRY = Quasi-Stationary or Near Stationary (click to enlarge image) Standard Text Abbreviations
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