Subj : Wx Terms (M)(5)
To : All
From : Daryl Stout
Date : Tue Nov 14 2017 12:05 am
Moisture Ridge
An axis of relatively high dew point values. This axis is sometimes
referred to as a 'moist tongue'.
Molecule
The smallest particle of a substance that retains the properties of the
substance and is composed of one or more atoms.
Monitor Stage
The stage which, when reached by a rising stream, represents the level
where appropriate officials (e.g., county sheriff, civil defense
officials, or bypass gate operators) are notified of the threat of
possible flooding. (Used if different from action stage, and at the
discretion of the WFO or river forecast center [RFC].) The term
"alert stage" is to be used instead of warning stage. Monitor stage or
caution stage may be used instead of alert stage in some parts of the
country.
Monostatic Radar
A radar that uses a common antenna for both transmitting and receiving.
Monsoon
A thermally driven wind arising from differential heating between a land
mass and the adjacent ocean that reverses its direction seasonally.
Monthly Climatological Report
This climatological product is issued once a month by each National
Weather Service office. It is a mix of tabular and narrative information.
It is organized so that similar items are grouped together (i.e.,
temperature, precipitation, wind, heating/cooling degree information,
etc.).
Morning Glory
An elongated cloud band, visually similar to a roll cloud, usually
appearing in the morning hours, when the atmosphere is relatively stable.
Morning glories result from perturbations related to gravitational waves
in a stable boundary layer. They are similar to ripples on a water
surface; several parallel morning glories often can be seen propagating
in the same direction.
MOS
Model Output Statistics - the Hydrometeorological Center (HPC) produces
a short range (6 to 60 hours) MOS guidance package generated from the
NGM, GFS, and ETA models for over 300 individual stations in the
continental United States. These alphanumeric messages are made available
at approximately 0400 and 1600 UTC for the 0000 and 1200 UTC forecast
cycles, respectively. Model Output Statistics are a set of statistical
equations that use model output to forecast the probability of
precipitation, high and low temperature, cloud cover, and precipitation
amount for many cities across the USA. The statistical equations were
specifically tailored for each location, taking into account factors
such as each location's climate.
Mostly Clear
When the predominant/average sky condition is covered 1/8 to 2/8 with
opaque (not transparent) clouds. Sometimes referred to as Mostly Sunny
if this condition is present during daylight hours.
Mostly Cloudy
When the predominant/average sky condition is covered by more than half,
but not completely covered by opaque (not transparent) clouds. In other
words, 5/8 to 7/8 of the sky is covered by opaque clouds. Same as
Considerable Cloudiness.
Mostly Sunny
Same as Mostly Clear, except only applicable during daylight hours; when
the predominant/average sky condition is covered 1/8 to 2/8 with opaque
(not transparent) clouds.
Mount Wilson Magnetic Classifications
In solar-terrestrial terms, a classification system for sunspots:
Alpha: Denotes a unipolar sunspot group.
Beta: A sunspot group having both positive and negative magnetic
polarities, with a simple and distinct division between the polarities.
Beta-Gamma: A sunspot group that is bipolar but in which no continuous
line can be drawn separating spots of opposite polarities.
Delta: A complex magnetic configuration of a solar sunspot group
consisting of opposite polarity umbrae within the same penumbra.
Gamma: A complex active region in which the positive and negative
polarities are so irregularly distributed as to prevent classification
as a bipolar group.
Mountain Wave
The wavelike effect, characterized by updrafts and downdrafts, that
occurs above and behind a mountain range when rapidly flowing air
encounters the mountain range's steep front.
Mountain Wind System
The system of diurnal winds that forms in a complex terrain area,
consisting of mountain-plain, along-valley, cross-valley and slope
wind systems.
Mountain-Plain Wind System
A closed, large-scale, thermally driven circulation between the
mountains and the surrounding plain. The mountain-to-plain flow making
up the lower branch of the closed circulation usually occurs during
nighttime, while the plain-to-mountain flow occurs during daytime.
Mountainado
A vertical-axis eddy produced in a downslope windstorm by the vertical
stretching of horizontal roll vortices produced near the ground by
vertical wind shear. Mountainadoes, when carried by the mean wind, can
produce strong horizontal shears and wind gusts that are much more
damaging than the general prevailing wind speeds.
MOV
Move
Movable Bed
In hydrologic terms, a stream bed made up of materials readily
transportable by the stream flow.
MOVG
moving
MR
more
MRF
Medium Range Forecast model, the medium-range computer model run by the
United States (NOAA). The output from this model is part of what is now
known as the GFS model, so the term MRF is no longer widely used.
MRGL
Marginal
MRNG
Morning
MSG
Message
MSL
(Mean Sea Level) - The arithmetic mean of hourly water elevations
observed over a specific 19-year tidal epoch.
MSLP
Mean sea level pressure
MST
Mountain Standard Time
MSTLY
Mostly
MSTR
Moisture
MT
1) Mountain
2) Montana
MTN
Mountain
MTNS
Mountains
MTS
Mountains
Mud Slide
Fast moving soil, rocks and water that flow down mountain slopes and
canyons during a heavy downpour of rain.
Muggy
A subjective term for warm and excessively humid conditions.
MULI
Most Unstable Lifted Index - Lifted Index (LI) calculated using a parcel
from the pressure level that results in the Most Unstable value
(lowest value) of LI possible.
Multicell Thunderstorm
These thunderstorms are organized in clusters of at least 2-4 short-lived
cells. Each cell generates a cold air outflow and these individual
outflows combine to form a large gust front. Convergence along the gust
front causes new cells to develop every 5 to 15 minutes. The cells move
roughly with the mean wind. However, the area (storm) motion usually
deviates significantly from the mean wind due to discrete propagation
(new cell development) along the gust front. The multicellular nature of
the storm is usually apparent on radar with multiple reflectivity cores
and maximum tops.
Multiple Doppler Analysis
The use of more than one radar (and hence more than one look angle) to
reconstruct spatial distributions of the 2D or 3D wind field, which
cannot be measured from a single radar alone. Includes dual Doppler,
triple Doppler, and overdetermined multiple Doppler analysis.
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