Subj : Wx Terms (U)(2)
To : All
From : Daryl Stout
Date : Sun Oct 22 2017 09:56 am
Upper-air Weather Chart
Weather maps that are produced for the portion of the atmosphere above
the lower troposphere, generally at and above 850 mb. Isolines on these
maps usually represent the heights of a constant pressure surface, such
as the 500 mb surface.
UPR
Upper
Upslope Flow
Same as Orographic Lifting; air that flows toward higher terrain, and
hence is forced to rise. The added lift often results in widespread low
cloudiness and stratiform precipitation if the air is stable, or an
increased chance of thunderstorm development if the air is unstable.
Upslope Fog
A fog that forms when moist, stable air is carried up a mountain slope.
UPSLP
Upslope
Upstream
Towards the source of flow, or located in the area from which the flow
is coming.
Upstream Slope
The part of the dam which is in contact with the reservoir water. On
earthen dams, this slope must be protected from the erosive action of
waves by rock riprap or concrete.
UPSTRM
Upstream
Upwelling
In ocean dynamics, the upward motion of sub-surface water toward the
surface of the ocean. This is often a source of cold, nutrient-rich
water. Strong upwelling occurs along the equator where easterly winds
are present. Upwelling also can occur along coastlines, and is important
to fisheries and birds in California and Peru.
Urban and Small Stream Flood Advisory
This advisory alerts the public to flooding which is generally only an
inconvenience (not life-threatening) to those living in the affected
area. Issued when heavy rain will cause flooding of streets and
low-lying places in urban areas. Also used if small rural or urban
streams are expected to reach or exceed bankfull. Some damage to homes
or roads could occur.
Urban and Small Stream Flooding
Flooding of small streams, streets, and low-lying areas, such as
railroad underpasses and urban storm drains. This type of flooding is
mainly an inconvenience and is generally not life threatening nor is it
significantly damaging to property.
Urban Flash Flood Guidance
A specific type of flash flood guidance which estimates the average
amount of rain needed over an urban area during a specified period of
time to initiate flooding on small, ungaged streams in the urban area.
Urban Flooding
Flooding of streets, underpasses, low lying areas, or storm drains.
This type of flooding is mainly an inconvenience and is generally not
life threatening.
Urban Heat Island
The increased air temperatures in urban areas in contrast to cooler
surrounding rural areas.
UTC
By international agreement, the local time at the prime meridian, which
passes through Greenwich, England. Prior to 1972, this time was called
Greenwich Mean Time (GMT) but is now referred to as Coordinated
Universal Time or Universal Time Coordinated (UTC). It is a coordinated
time scale, maintained by the Bureau International des Poids et Mesures
(BIPM). It is also known a "Z time" or "Zulu Time".
More about UTC, and a table to convert UTC to your local time is posted
at:
http://www.srh.noaa.gov/jetstream/remote/radarfaq.htm#utc
UV Index
Ultraviolet Index
This index provides important information to help you plan your outdoor
activities in ways that prevent overexposure to the sun's rays. It was
designed by the National Weather Service (NWS) and the Environmental
Protection Agency (EPA). Unlike some countries' indices, the United States
UV Index is not based upon surface observations. Rather, it is computed
using forecasted ozone levels, a computer model that relates ozone levels
to UV incidence on the ground, forecasted cloud amounts, and the
elevation of the forecast cities. The calculation starts with
measurements of current total ozone amounts for the entire globe,
obtained via two satellites operated by the National Oceanic and
Atmospheric Administration (NOAA). These data are then used to produce a
forecast of ozone levels for the next day at various points around the
country.
Category UV Index Time to Burn Actions to Take
Minimal 0 - 2 60 min. + Apply SPF sunscreen.
Low 3 - 4 45 min. Apply SPF sunscreen, wear a hat.
Moderate 5 - 6 30 min. Apply SPF 15, wear a hat.
High 7 - 9 15 - 24 min. Apply SPF 15 to 30, wear a hat and
sunglasses. Limit midday exposure.
Very High 10+ 10 min. Apply SPF 30; wear a hat, sunglasses,
and protective clothing; limit
midday exposure.
UVM
Upward Vertical Motion (also known as Upward Vertical Velocity)
UVV
Upward Vertical Velocity (rising air)
UWNDS
Upper Winds
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