Subj : Wx Terms (M)(1) To : All From : Daryl Stout Date : Mon Aug 14 2017 07:24 am M 3000 In solar-terrestrial terms, the optimum high frequency radio wave with a 3000 km range, which reflects only once from the ionosphere (single hop transmission). M2/S2 m2/s2 (meters squared per second squared), unit of measure equivalent to J/kg (joules per kilogram). Mackeral Sky The name given to cirrocumulus clouds with small vertical extent and composed of ice crystals. The rippled effect gives the appearance of fish scales. Macroburst A convective downdraft with an affected outflow area of at least 2 miles wide and peak winds lasting between 5 and 20 minutes. Intense macrobursts may cause tornado-force damage of up to F3 intensity. Macroscale Large scale, characteristic of weather systems several hundred to several thousand kilometers in diameter. Madden-Julian Oscillation (abbrev. MJO)- Tropical rainfall exhibits strong variability on time scales shorter than the seasonal El Ni¥o-Southern Oscillation (ENSO). These fluctuations in tropical rainfall often go through an entire cycle in 30-60 days, and are referred to as the Madden-Julian Oscillation or intraseasonal oscillations. The intraseasonal oscillations are a naturally occurring component of our coupled ocean-atmosphere system. They significantly affect the atmospheric circulation throughout the global Tropics and subtropics, and also strongly affect the wintertime jet stream and atmospheric circulation features over the North Pacific and western North America. As a result, they have an important impact on storminess and temperatures over the United States. During the summer these oscillations have a modulating effect on hurricane activity in both the Pacific and Atlantic basins. MAFOR (Great Lakes Marine Forecast) - A National Weather Service coded summary appended to each of the Great Lakes Open Lakes forecasts. Magflare In solar-terrestrial terms, a geomagnetic and/or cosmic storm has been associated with this flare. Magnetic Bay In solar-terrestrial terms, a relatively smooth excursion of the H (horizontal) component of the geomagnetic field away from and returning to quiet levels. Magnetogram In solar-terrestrial terms, solar magnetograms are a graphic representation of solar magnetic field strengths and polarity. Magnetopause In solar-terrestrial terms, the boundary layer between the solar wind and the magnetosphere. Magnetosphere In solar-terrestrial terms, the magnetic cavity surrounding the earth, carved out of the passing solar wind by virtue of the geomagnetic field, which prevents, or at least impedes, the direct entry of the solar wind plasma into the cavity. Main Stem In hydrologic terms, the reach of a river/stream formed by the tributaries that flow into it. Main Synoptic Times The times of 0000, 0600, 1200, and 1800 UTC. Also known as the standard synoptic times. MAINT Maintain Major Flare In solar-terrestrial terms, this flare is the basis for the forecast of geomagstorm, cosmic storm and/or protons in the earth's vicinity. Major Flooding A general term including extensive inundation and property damage. (Usually characterized by the evacuation of people and livestock and the closure of both primary and secondary roads.) Major Hurricane A hurricane which reaches Category 3 (sustained winds greater than 110 mph) on the Saffir/Simpson Hurricane Scale. MALR Moist Adiabatic Lapse Rate- The rate at which the temperature of a parcel of saturated air decreases as the parcel is lifted in the atmosphere. The moist adiabatic lapse rate (abbreviated MALR) is not a constant like the dry adiabatic lapse rate but is dependent on parcel temperature and pressure. Mammatus Clouds Rounded, smooth, sack-like protrusions hanging from the underside of a cloud (usually a thunderstorm anvil). Mammatus clouds often accompany severe thunderstorms, but do not produce severe weather; they may accompany non-severe storms as well. MAP Mean Areal Precipitation- The average rainfall over a given area, generally expressed as an average depth over the area. Mare's Trail The name given to thin, wispy cirrus clouds composed of ice crystals that appear as veil patches or strands, often resembling a horse's tail. MAREP (MArine REPort) A voluntary marine observation program of the National Weather Service whose goal is to solicit meteorological and oceanographic observations in plain language from recreational and small commercial mariners who are not part of Voluntary Observing Ship program. Marginal Visual Flight Rules (Abbrev. MVFR) - In an aviation product, refers to the general weather conditions pilots can expect at the surface. VFR stands for Visual Flight Rules and MVFR means Minimum or Marginal Visual Flight Rules. MVFR criteria means a ceiling between 1,000 and 3,000 feet and/or 3 to 5 miles visibility. Marine Inversion Temperature inversion produced when cold marine air underlies warmer air. Marine Push A replacement of the current air mass with air from off the ocean. Temperatures are much cooler and relative humidities much higher. The air mass is generally much more stable in this situation. Marine Small Craft Thunderstorm Advisory A marine warning issued by Environment Canada Atmospheric Environment Branch when the possibility of thunderstorms is greater than 40 percent. Marine Small Craft Wind Warning A marine warning issued by Environment Canada Atmospheric Environment Branch for winds which are forecasted to be in the 20-33 knot range inclusive. Marine Weather Statement A National Weather Service product to provide mariners with details on significant or potentially hazardous conditions not otherwise covered in existing marine warnings and forecasts. Marine weather statements are also used to supplement special marine warnings. Marine Zone Specific, defined over-water areas contained in the various NWS marine forecasts. These are the equivalent of "zones" in the public forecast program. Maritime Air Mass An air mass influenced by the sea. It is a secondary characteristic of an air mass classification, signified by the small "m" before the primary characteristic, which is based on source region. For example, mP is an air mass that is maritime polar in nature. Also known as a marine air mass. Maritime Polar Air Mass An air mass characterized by cold, moist air. Abbreviated mP. Maritime Tropical Air Mass An air mass characterized by warm, moist air. Abbreviated mT. MAROB A voluntary marine observation program of the National Weather Service in the early stages of development whose goal is to solicit meteorological and oceanographic observations in coded format from recreational and small commercial mariners who are not part of the more in-depth Voluntary Observing Ship program. MARS A voluntary marine observation program of the National Weather Service whereby U.S. Coast Guard Sector Stations report marine weather conditions from several shore locations within their operating area. The reports are in an abbreviated plain language format with fixed fields. Massif A compact portion of a mountain range, containing one or more summits. MAV AVN MOS Guidance MAX Maximum Max Parcel Level (MPL) This signifies the highest attainable level that a convective updraft can reach; therefore, it is a good indication of how tall a thunderstorm may reach. Maximum Spillway Discharge In hydrologic terms, spillway discharge (cfs) when reservoir is at maximum designed water surface elevation. Maximum Sustained Surface Wind When applied to a particular weather system, refers to the highest one-minute average wind (at an elevation of 10 meters with an unobstructed exposure) associated with that weather system at a particular point in time. --- þ Synchronet þ The Thunderbolt BBS - wx1der.dyndns.org .