Subj : Wx Terms (R)(4)
To : All
From : Daryl Stout
Date : Tue Sep 19 2017 12:08 am
Right Mover
A thunderstorm that moves appreciably to the right relative to the main
steering winds and to other nearby thunderstorms. Right movers typically
are associated with a high potential for severe weather. (Supercells
often are right movers).
Right Rear Quadrant
(Abbrev. RRQ) - Used interchangably with Right Entrance Region; the area
upstream from and to the right of an upper-level jet max (as would be
viewed looking along the direction of flow). Upward motion and severe
thunderstorm potential sometimes are increased in this area relative to
the wind speed maximum. See also exit region, left front quadrant.
Rime Ice
An opaque coating of tiny, white, granular ice particles caused by the
rapid freezing of supercooled water droplets on impact with an object.
See also clear ice.
RIOGD
Rio Grande
Riometer
(Relative Ionospheric Opacity meter). A specially designed radio receiver
for continuous monitoring of cosmic noise. The absorption of cosmic noise
in the polar regions is very sensitive to the solar low-energy cosmic ray
flux.
Rip Current
A relatively small-scale surf-zone current moving away from the beach.
Rip currents form as waves disperse along the beach causing water to
become trapped between the beach and a sandbar or other underwater
feature. The water converges into a narrow, river-like channel moving
away from the shore at high speed.
Rip Tide
See RIP CURRENTS
Riparian Zone
In hydrologic terms, a stream and all the vegetation on its banks.
River Basin
In hydrologic terms, drainage area of a river and its tributaries.
River Flood Statement
This product is used by the local National Weather Service Forecast
Office (NWFO) to update and expand the information in the River Flood
Warning. This statement may be used in lieu of a warning if flooding
is forecasted, imminent, or existing and it presents no threat to life
or property. The statement will also be used to terminate a River
Flood Warning.
River Flood Warning
This is product is issued by the local National Weather Service Forecast
Office (NWFO) when forecast points (those that have formal gaging sites
and established flood stages) at specific communities or areas along
rivers where flooding has been forecasted, is imminent, or is in
progress. Flooding is defined as the inundation of normally dry areas as
a result of increased water levels in an established water course. The
flood warning is based on the RVF product from the River Forecast Center
(RFC) in Minneapolis, Minnesota. The flood warning normally specifies
crest information. It usually occurs 6 hours or later after the causative
event and it is usually associated with widespread heavy rain and/or snow
melt or ice jams.
It will contain the forecast point covered by the warning, the current
stage (if it is available), and the established flood stage. It will also
contain the forecasted crest from the River Forecast Center (RFC) in
Minneapolis, Minnesota. From this forecasted crest, the NWFO will be able
to determine which areas will be affected by the river flooding. This
information will be included in the warning. Finally, the statement will
include a site/event specific call to action.
River Flooding
The rise of a river to an elevation such that the river overflows its
natural banks causing or threatening damage.
River Forecast
An internal product issued by RFCs to other NWS offices. An RVF contains
stage and/ or flow forecasts for specific locations based on existing,
and forecasted hydrometeorologic conditions. The contents of these
products are used by the HSA office to prepare Flood Warnings (FLW),
Flood Statements (FLS), River Statements (RVS), as well as other products
available to the public.
River Forecast Center
Centers that serve groups of Weather Service Forecast offices and Weather
Forecast offices, in providing hydrologic guidance and is the first
echelon office for the preparation of river and flood forecasts and
warnings.
River Gage
A device for measuring the river stage.
River Gage Datum
The arbitrary zero datum elevation which all stage measurements are made
from.
River Ice Statement
A public product issued by the RFC containing narrative and numeric
information on river ice conditions.
River Observing Station
An established location along a river designated for observing and
measuring properties of the river.
River Recreation Statement
A statement released by the NWS to inform river users of current and
forecast river and lake conditions. These statements are especially
useful for planning purposes.
River Statement
A NWS product issued to communicate notable hydrologic conditions which
do not involve flooding, i.e., within river bank rises, minor ice jams,
etc.
River System
In hydrologic terms, all of the streams and channels draining a river
basin.
Rocketsonde
A type of radiosonde that is shot into the atmosphere by a rocket,
allowing it to collect data during its parachute descent from a higher
position in the atmosphere than a balloon could reach.
Rockfill Dam
In hydrologic terms, an embankment dam of earth or rock in which the
material is placed in layers and compacted by using rollers or rolling
equipment.
Rogue Wave
Commonly used term by mariners of a wave of an unexpected wave of much
greater height or steepness than other waves in the prevailing sea or
swell system. Rogue waves have been part of marine folklore for centuries.
They are generally considered to be unexpectedly high waves which in some
instances come from a direction different from the predominant waves in
the local area. A single rogue wave has certainly been known to spell
disaster for the mariner. They have, over the past twenty or thirty years,
come to be recognized as unique phenomena albeit with several possible
causes.
(1) Constructive interference. Several different wave trains of differing
speeds and directions meet at the same time. The heights of the crests
are additive so that an extreme wave may result when very high waves are
included in the wave trains. The effect is normally short lived since the
wave trains continue to separate and move on.
(2) Focusing of wave energy. When storm forced waves are developed in a
water current counter to the wave direction an interaction can take place
which results in a shortening of the wave frequency. The result is the
superimposing of the wave trains and the generation of extreme waves.
Examples of currents where these are sometimes seen are the Gulf Stream
and Agulhas current. Extreme wave developed in this regime tend to be
longer lived.
(3) Normal part of the wave spectrum. The generation of waves on water
results not in a single wave height but in a spectrum of waves distributed
from the smallest capillary waves to large waves indeed. Within this
spectrum there is a finite possibility of each of the wave heights to
occur with the largest waves being the least likely. The wave height most
commonly observed and forecast is the significant wave height. This is
defined as the average of the one third highest waves. The probability of
encountering such a wave is about 1 in 10 while 1 in 1000 waves will be
nearly double the significant wave height or higher. This is thought to
be the source of at least some reports of rogue waves.
Roll Cloud
A low, horizontal tube-shaped arcus cloud associated with a thunderstorm
gust front (or sometimes with a cold front). Roll clouds are relatively
rare; they are completely detached from the thunderstorm base or other
cloud features, thus differentiating them from the more familiar shelf
clouds. Roll clouds usually appear to be "rolling" about a horizontal
axis, but should not be confused with funnel clouds.
Rolled Filled Dam
In hydrologic terms, an embankment dam of earth or rock in which the
material is placed in layers and compacted by using rollers or rolling
equipment.
Rope
(Also "Rope Funnel") - a narrow, often contorted condensation funnel
usually associated with the decaying stage of a tornado. See rope stage.
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