Subj : Wx Terms (O)(2)
To : All
From : Daryl Stout
Date : Wed Aug 16 2017 12:09 am
OTLK
Outlook
OTR
Other
OTRW
Otherwise
Outer Convective Band
Bands in a hurricane that occur in advance of main rain shield and up
to 300 miles from the eye of the hurricane. The typical hurricane has
two or three bands (and sometimes more) which are comprised of cells
resembling ordinary thunderstorms. Wind gusts are usually higher in
these bands than in the Pre-Hurricane Squall Line.
Outflow
Air that flows outward from a thunderstorm.
Outflow Boundary
A storm-scale or mesoscale boundary separating thunderstorm-cooled air
(outflow) from the surrounding air; similar in effect to a cold front,
with passage marked by a wind shift and usually a drop in temperature.
Outflow boundaries may persist for 24 hours or more after the
thunderstorms that generated them dissipate, and may travel hundreds
of miles from their area of origin.
New thunderstorms often develop along outflow boundaries, especially
near the point of intersection with another boundary (cold front, dry
line, another outflow boundary, etc.; see triple point).
Outflow Channel
In hydrologic terms, a natural stream channel which transports
reservoir releases.
Outgoing Longwave Radiation
Outgoing Longwave Radiation is a polar satellite derived measurement
of the radiative character of energy radiated from the warmer earth
surface to cooler space. This measurement provides information on
cloud-top temperature which can be used to estimate tropical
precipitation amounts which is important in forecasting weather and
climate.
Outlet
In hydrologic terms, an opening through which water can be freely
discharged from a reservoir.
Outlet Discharge Structure
In hydrologic terms, protects the downstream end of the outlet pipe
from erosion and is often designed to slow down the velocity of
released water to prevent erosion of the stream channel.
Outlook
An outlook is used to indicate that a hazardous weather or hydrologic
event may develop. It is intended to provide information to those who
need considerable lead time to prepare for the event.
OVC
Overcast- An official sky cover classification for aviation weather
observations, when the sky is completely covered by an obscuring
phenomenon. This is applied only when obscuring phenomenon aloft are
present--that is, not when obscuring phenomenon are surface-based,
such as fog.
Overcast
(Abbrev. OVC)- An official sky cover classification for aviation
weather observations, when the sky is completely covered by an
obscuring phenomenon. This is applied only when obscuring phenomenon
aloft are present--that is, not when obscuring phenomenon are
surface-based, such as fog.
Overhang
Radar term indicating a region of high reflectivity at middle and
upper levels above an area of weak reflectivity at low levels. (The
latter area is known as a weak-echo region, or WER.) The overhang is
found on the inflow side of a thunderstorm (normally the south or
southeast side).
Overland Flow
In hydrologic terms, the flow of rainwater or snowmelt over the land
surface toward stream channels. After it enters a watercourse it
becomes runoff.
Overrunning
A weather pattern in which a relatively warm air mass is in motion
above another air mass of greater density at the surface. Embedded
thunderstorms sometimes develop in such a pattern; severe
thunderstorms (mainly with large hail) can occur, but tornadoes are
unlikely.
Overrunning often is applied to the case of warm air riding up over
a retreating layer of colder air, as along the sloping surface of a
warm front. Such use of the term technically is incorrect, but in
general it refers to a pattern characterized by widespread clouds
and steady precipitation on the cool side of a front or other boundary.
Overshooting Top
(or Penetrating Top) - A dome-like protrusion above a thunderstorm
anvil, representing a very strong updraft and hence a higher potential
for severe weather with that storm. A persistent and/or large
overshooting top (anvil dome) often is present on a supercell.
A short-lived overshooting top, or one that forms and dissipates in
cycles, may indicate the presence of a pulse storm.
OVNGT
Overnight
OVR
Over
OVRN
Overrun
OVRNGT
Overnight
Ozone
A form of oxygen, O3. A powerful oxidizing agent that is considered a
pollutant in the lower troposphere but an essential chemical in the
stratosphere where it protects the earth from high-energy ultraviolet
radiation from the sun.
Ozone Action Day
A "heads-up" message issued by the Department of Natural Resources
(DNR) through the National Weather Service when ozone levels may reach
dangerous levels the next day. This message encourages residents to
prevent air pollution by postponing the use of lawn mowing, motor
vehicles, boats, as well as filling their vehicle gas tanks.
Ozone Advisory
It is issued by the Department of Natural Resources (DNR) through the
National Weather Service when ozone levels reach 100. Ozone levels
above 100 are unhealthy for people with heat and/or respiratory ailments.
Ozone Hole
A severe depletion of stratospheric ozone over Antarctica that occurs
each spring. The possibility exists that a hole could form over the
Arctic as well. The depletion is caused by a chemical reaction
involving ozone and chlorine, primarily from human produced sources,
cloud particles, and low temperatures.
Ozone Layer
An atmospheric layer that contains a high proportion of oxygen that
exists as ozone. It acts as a filtering mechanism against incoming
ultraviolet radiation. It is located between the troposphere and the
stratosphere, around 9.5 to 12.5 miles (15 to 20 kilometers) above
the earth's surface.
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