Subj : Wx Terms (U)(1)
To   : All
From : Daryl Stout
Date : Sat Jul 22 2017 12:08 am

U Burst
In solar-terrestrial terms, a fast radio burst spectrum of a flare. It
has a U-shaped appear- ance in an intensity-vs.-frequency plot

U.S. Geological Survey
(Abbrev. USGS)- The Federal Agency chartered in 1879 by congress to
classify public lands, and to examine the geologic structure, mineral
resources, and products of the national domain. As part of its mission,
the USGS provides information and data on the Nation's rivers and
streams that are useful for mitigation of hazards associated with floods
and droughts.

UCP
(Unit Control Position): The WSR-88D radar operator uses this to control
the entire radar system. One of the main things that the radar operator
will do at the UCP is change volume scan strategies of the antenna.
These volume scan strategies tell the radar how many elevation angles
will be used during a single volume scan (a volume scan is the
completion of a sequence of elevation angles), and the amount of time it
will take to complete that sequence of elevation cuts, each one being a
single rotation of the antenna's 1 degree beam at selected elevation
angles. The WSR-88D uses 3 scan strategies. They are the following:

14 elevation angles in 5 minutes (this is used during severe weather
situations), 9 elevation angles in 6 minutes (this is used when there is
precipitation within 248 nautical miles of the radar), and 5 elevation
angles in 10 minutes (this is used when there is no precipitation within
248 nautical miles). The radar operator at the UCP can also adjust the
radar products and help the users out with their communication problems.

UGC
(Universal Geographic Code) - (e.g. ANZ300 for Western Long Island Sound)
are used in many National Weather Service text products to provide
geographical information. This allows users easy automated processing and
redistribution of the information. More specifically, the purpose of the
UGC are to specify the affected geographic area of the event, typically
by state, county (or parish), or unique NWS zone (land and marine). The
only exception to the above is to define the weather synopsis part of
certain marine products.

UKMET
A medium-range (3 to 7 day) numerical weather prediction model operated
by the United Kingdom METeorological Agency. It has a resolution of 75
kilometers and covers the entire northern hemisphere. Forecasters use
this model along with the ECMWF and GFS in making their extended
forecasts (3 to 7 days).

ULJ
Upper Level Jet

Ultra High Frequency (UHF)
Those radio frequencies exceeding 300 MHz

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.

Ultraviolet Radiation
Electromagnetic radiation of shorter wavelength than visible radiation
but longer than x-rays.

Umbra
In solar-terrestrial terms, the dark core or cores (umbrae) in a sunspot
with penumbra, or a sunspot lacking penumbra.

Undercurrent
In hydrologic terms, a current below the upper currents or surface of a
fluid body.

Underflow
The lateral motion of water through the upper layers until it enters a
stream channel. This usually takes longer to reach stream channels than
runoff. This also called subsurface storm flow.

Undersun
An optical effect seen by an observer above a cloud deck when looking
toward the sun, as sunlight is reflected upwards off the faces of ice
crystals in the cloud deck. [Also known as subsun.]

Undertow
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.

Unimodal
A distribution having only one localized maximum, i.e., only one peak.

Unit Control Position
The WSR-88D radar operator uses this to control the entire radar system.
One of the main things that the radar operator will do at the UCP is
change volume scan strategies of the antenna. These volume scan
strategies tell the radar how many elevation angles will be used during
a single volume scan (a volume scan is the completion of a sequence of
elevation angles), and the amount of time it will take to complete that
sequence of elevation cuts, each one being a single rotation of the
antenna's 1 degree beam at selected elevation angles. The WSR-88D uses
3 scan strategies. They are the following:

14 elevation angles in 5 minutes (this is used during severe weather
situations), 9 elevation angles in 6 minutes (this is used when there
is precipitation within 248 nautical miles of the radar), and 5
elevation angles in 10 minutes (this is used when there is no
precipitation within 248 nautical miles). The radar operator at the
UCP can also adjust the radar products and help the users out with
their communication problems.

Unit Hydrograph
The discharge hydrograph from one inch of surface runoff distributed
uniformly over the entire basin for a given time period.

Universal Geographic Code
(UGC) - UGC's, (e.g. ANZ300 for Western Long Island Sound) are used in
many National Weather Service text products to provide geographical i
nformation. This allows users easy automated processing and
redistribution of the information. More specifically, the purpose of
the UGC are to specify the affected geographic area of the event,
typically by state, county (or parish), or unique NWS zone (land and
marine). The only exception to the above is to define the weather
synopsis part of certain marine products.

Universal Time (UT)
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

UNSBL
Unseasonable

Unsettled
In solar-terrestrial terms, with regard to geomagnetic levels, a
descriptive word specifically meaning that 8 is less than or equal to
the Ap Index which is less than or equal to 15.

Unstable Air
Air that is able to rise easily, and has the potential to produce clouds,
rain, and thunderstorms.

UNSTBL
Unstable

Up-valley Wind
A diurnal thermally driven flow directed up a valley's axis, usually
occurring during daytime; part of the along-valley wind system.

Updraft
A small-scale current of rising air. If the air is sufficiently moist,
then the moisture condenses to become a cumulus cloud or an individual
tower of a towering cumulus or Cb.

Upper Level
In weather observing, the term applies to the portion of the atmosphere
that is above the lower troposphere, generally 850 hPa and above.

Upper Level Disturbance
A disturbance in the upper atmospheric flow pattern which is usually
associated with clouds and precipitation. This disturbance is
characterized by distinct cyclonic flow, a pocket of cold air, and
sometimes a jet streak. These features make the air aloft more unstable
and conducive to clouds and precipitation.

Upper Level System
A general term for any large-scale or mesoscale disturbance capable of
producing upward motion (lift) in the middle or upper parts of the
atmosphere. This term sometimes is used interchangeably with impulse
or shortwave.



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