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Hurricanes: Science and Society
Glossary - M
M
major hurricane
A hurricane that reaches Category 3 (sustained winds greater than 110 mph) on the Saffir-Simpson Hurricane Wind Scale. Source NOAA-NHC.
mandatory evacuation
A situation where authorities put maximum emphasis on encouraging evacuation and limiting ingress to potentially impacted areas. These events also occur when evacuation transportation plans go into effect. Source: US DOT
mangrove
Mangroves are trees and shrubs that grow in tropical and subtropical tidelands throughout the world. Mangroves grow in areas that are frequently inundated with salt water due to tidal activity of gulfs, seas and oceans. Mangroves are able to thrive salt water inundation because of specialized rooting structures (such as prop roots and pneumatophores), specialized reproduction (vivipary or live birth) and the ability to exclude or excrete salt. Source: Lee County Government
Maximum of Maximum (MOM) maps
A MOM is a composite map showing the maximum inundation at every grid cell of the SLOSH model resulting from 2,000 to 4,000 model runs forced by a family of hurricanes with different intensity, size, direction, forward speed, and landfall point.
maximum surface wind speed
The maximum 10-minute averaged (1-minute averaged in the U.S. only) wind speed found anywhere in the tropical cyclone at 10 meters (33 ft) height.
maximum sustained winds
Steady winds within a tropical cyclone. Unlike gusts, maximum sustained winds must last over twenty seconds continuously.
Mesoscale Convective Complex (MCC)
A large mesoscale convective system, generally round or oval-shaped, which normally reaches peak intensity at night. The formal definition includes specific minimum criteria for size, duration, and eccentricity (i.e., roundness), based on the cloud shield as seen on infrared satellite photographs. Source: NOAA-NWS ERH
Mesoscale Convective System (MCS)
A complex of thunderstorms which becomes organized on a scale larger than the individual thunderstorms, and normally persists for several hours or more. MCSs may be round or linear in shape, and include systems such as tropical cyclones, squall lines, and MCCs (among others). MCS often is used to describe a cluster of thunderstorms that does not satisfy the size, shape, or duration criteria of an MCC. Source: NOAA-NWS ERH
Mesoscale Convective Vortex (MCV)
A low-pressure center within an mesoscale convective system (MCS) that pulls winds into a circling pattern, or vortex.
meteorologist
A person who studies meteorology. Some examples include research meteorologist, climatologist, operational meteorologist, TV meteorologist. Source: NOAA-NWS ERH
microwave radiation
Electromagnetic radiation generally in the frequency range between 300 MHz and 300 GHz (free-space wavelengths between 1 and 1000 mm). Within these frequencies lie the UHF, SHF, and EHF radio frequency bands. Radars operate at microwave frequencies. Source: (c) 1999, American Meteorological Society. Used with permission.
mid-latitudes
The areas on earth between the tropics and the polar regions, roughly between 35°N and 65°S degrees.
mitigation
Actions that reduce the long-term risks to life and property from hurricanes.
mixing
[of the ocean]: Any process or series of processes by which parcels of ocean water with different properties are brought into contact, so that molecular diffusion (spreading out) erases the differences between them. Source: (c) 1999, American Meteorological Society. Used with permission.
molecule
The simplest structural unit of substance which can exist and still maintain the characteristics of that substance.
monsoon trough
The line in a weather map showing the locations of relatively minimum sea level pressure in a monsoon region (area of seasonal winds, strongest on the southern and eastern sides of Asia, but also occurring on the coasts of tropical regions such as Spain, northern Australia, Africa except the Mediterranean, Texas, and the western coasts of the United States and Chile). Most of the active transient disturbances producing the monsoon rain develop and move along the monsoon trough region.
multidecadal
Referring to a time span that involves multiple decades
multiple-nest grid configuration
A set of grids in a regional dynamical hurricane model where a high-resolution grid (with small spacing between grid points) is embedded in a larger, coarse-resolution grid (with more space between grid points). There can be any number of high-resolution grids embedded in any number of coarser resolution grids. In some models, the smaller high-resolution grid(s) follow the hurricane's forecast track while the larger, lower-resolution grid(s) remain stationary throughout the model forecast.