Subj : Wx Terms (T)(2)
To   : All
From : Daryl Stout
Date : Thu Sep 21 2017 12:06 am

Theta-e
(or Equivalent Potential Temperature) - The temperature a parcel of air
would have if

a) it was lifted until it became saturated,

b) all water vapor was condensed out, and

c) it was returned adiabatically (i.e., without transfer of heat or mass)
to a pressure of 1000 millibars.

Theta-e, which typically is expressed in degrees Kelvin, is directly
related to the amount of heat present in an air parcel. Thus, it is useful
in diagnosing atmospheric instability.

Theta-e Ridge
An axis of relatively high values of theta-e. Severe weather and excessive
rainfall often occur near or just upstream from a theta-e ridge.

THETAE
Abbreviation for Theta-e; the temperature a parcel of air would have if

a) it was lifted until it became saturated,

b) all water vapor was condensed out, and

c) it was returned adiabatically (i.e., without transfer of heat or mass)
to a pressure of 1000 millibars.

Theta-e, which typically is expressed in degrees Kelvin, is directly
related to the amount of heat present in an air parcel. Thus, it is
useful in diagnosing atmospheric instability.

Thin Line Echo
A narrow, elongated, non-precipitating echo. It is usually associated with
thunderstorm outflows, fronts, or other density discontinuities. It is
also known as a Fine Line.

THK
Thick/Thickness

THN
Thin

Three-Hour Rainfall Rate
This WSR-88D Radar product displays precipitation total (in inches) of
the current and past two clock hours as a graphical image. It displays
hourly precipitation total (in inches) as a graphical image (polar
format with resolution 1.1 nm by 1 degree). It is updated once an hour.
It is used to:

1) Assess rainfall intensities and amounts over a longer viewing
interval; and

2) Possibly adjust flash flood guidance values since the product
corresponds to the timing of Flash Flood Guidance values.

Threshold Runoff
In hydrologic terms, the runoff in inches from a rain of specified
duration that causes a small stream to slightly exceed bankfull. When
available, flood stage is used instead of slightly over bankfull.

THRFTR
Thereafter

THRU
Through

THRUT
Throughout

THSD
Thousand

Thunder
The sound caused by rapidly expanding gases in a lightning discharge.

Thunderstorm
A local storm produced by a cumulonimbus cloud and accompanied by
lightning and thunder.

Tidal Cycle
The periodic changes in the intensity of tides caused primarily by the
varying relations between the earth, moon, and sun.

Tidal Piling
Occurs when unusually high water levels occur as the result of an
accumulation of successive incoming tides that do not completely drain
due to opposing strong winds and/or waves.

Tidal Wave
See TSUNAMI

TIDE
On a buoy report, the water level in feet above or below Mean Lower Low
Water (MLLW).

Tide Anomaly
Actual water level minus the prediction.

Tide Prediction
The computation of tidal highs and lows at a given location resulting
from the gravitational interactions between the earth and primarily the
moon and sun.

Tides
The periodic (occurring at regular intervals) variations in the surface
water level of the oceans, bays, gulfs, and inlets. Tides are the result
of the gravitiational attraction of the sun and the moon on the earth.
The attraction of the moon is far greater than the attraction of the sun
due to the close proximity of the earth and the moon. The sun is 360 times
further from the earth than the moon. Therefore, the moon plays a larger
role than the sun in producing tides. Every 27.3 days, the earth and the
moon revolve around a common point. This means that the oceans and other
water bodies which are affected by the earth-moon system experience a new
tidal cycle every 27.3 days. Because of the physical processes which
occur to produce the tidal system, there are two high tides and two low
tides each day. Because of the angle of the moon with respect to the
earth, the two high tides each day do not have to be of equal height. The
same holds true for the two low tides each day. Tides also differ in
height on a daily basis. The daily differences between tidal heights is
due to the changing distance between the earth and the moon. Scientists
use measurements of the height of the water level to examine tides and the
various phenomena which influence tides, such as hurricanes and winter
storms.

TIL
Until

Tilt
It describes a storm in which a line connecting the centroid of a mid
level storm component to the centroid of the lowest storm component is
to the right or the rear of the direction of motion.

Tilt Sequence
Radar term indicating that the radar antenna is scanning through a series
of antenna elevations in order to obtain a volume scan.

Tilted Storm
A thunderstorm or cloud tower which is not purely vertical but instead
exhibits a slanted or tilted character. It is a sign of vertical wind
shear, a favorable condition for severe storm development.

Tilted Updraft
A thunderstorm updraft which is not purely vertical but instead exhibits
a slanted or tilted character. It is a sign of vertical wind shear, a
favorable condition for severe storm development.

Tipping-Bucket Rain Gage
A precipitation gage where collected water is funneled into a two
compartment bucket; 0.01, 0.1 mm, or some other designed quantity of rain
will fill one compartment and overbalance the bucket so that it tips,
emptying into a reservoir and moving the second compartment into place
beneath the funnel. As the bucket is tipped, it actuates an electric
circuit.

TKE
Turbulent Kinetic Energy

TMW
Tomorrow

TNDCY
Tendency

TNGT
Tonight

Toe of Dam
(Upstream and Downstream) : The junction of the face of a dam with the
ground surface.

TOP
Cloud Top

Topography
The shape of the land.

TOR
Tornado (or) Tornado Warning

Tornado
A violently rotating column of air, usually pendant to a cumulonimbus,
with circulation reaching the ground. It nearly always starts as a funnel
cloud and may be accompanied by a loud roaring noise. On a local scale,
it is the most destructive of all atmospheric phenomena.

Tornado Family
A series of tornadoes produced by a single supercell, resulting in damage
path segments along the same general line.

Tornado Vortex Signature
An image of a tornado on the Doppler radar screen that shows up as a small
region of rapidly changing wind speeds inside a mesocyclone. The
following velocity criteria is normally required for recognition:

Velocity difference between maximum inbound and outbound (shear) is
greater than or equal to 90 knots at less than 30 nmi and is greater than
or equal to 70 knots between 30 and 55 nmi. It shows up as a red upside
down triangle on the Storm Relative Velocity Display. Existence of a TVS
strongly increases the probability of tornado occurrence, but does not
guarantee it; therefore, the feature triggering it must be examined
closely by the radar operator. A TVS is not a visually observable feature.



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