Subj : Wx Terms (T)(1)
To   : All
From : Daryl Stout
Date : Sat Oct 21 2017 12:04 am

T
Thunderstorm

T Rolls
Transverse Rolls - elongated low-level clouds, arranged in parallel bands
and aligned parallel to the low-level winds but perpendicular to the
mid-level flow. Transverse rolls are one type of transverse band, and
often indicate an environment favorable for the subsequent development of
supercells. Since they are aligned parallel to the low-level inflow, they
may point toward the region most likely for later storm development.

TAF
Terminal Aerodrome Forecast

TAFB
Tropical Analysis and Forecast Branch (of the TPC)

Tail Cloud
A horizontal, tail-shaped cloud (not a funnel cloud) at low levels
extending from the precipitation cascade region of a supercell toward the
wall cloud (i.e., it usually is observed extending from the wall cloud
toward the north or northeast). The base of the tail cloud is about the
same as that of the wall cloud. Cloud motion in the tail cloud is away
from the precipitation and toward the wall cloud, with rapid upward
motion often observed near the junction of the tail and wall clouds.
Compare with beaver tail, which is a form of inflow band that normally
attaches to the storm's main updraft (not to the wall cloud) and has a
base at about the same level as the updraft base (not the wall cloud).

Tail-End Charlie
Slang for the thunderstorm at the southernmost end of a squall line or
other line or band of thunderstorms. Since low-level southerly inflow of
warm, moist air into this storm is relatively unimpeded, such a storm
often has a higher probability of strengthening to severe levels than the
other storms in the line.

Tailwater Height
In hydrologic terms, height of water immediately downstream of the dam.

Target
Precipitation or other phenomena which produces echoes on a radar display.

TCU
Towering cumulus clouds

TD
Tropical Depression

TDA
Today

TDWR
Terminal Doppler Weather Radar

Teleconnection
Linkage between changes in atmospheric circulation occurring in widely
separated parts of the globe.

TEMP
Temperature- A measure of the internal energy that a substance contains.
This is the most measured quantity in the atmosphere.

Temperature
(Abbrev. TEMP)- The temperature is a measure of the internal energy that
a substance contains. This is the most measured quantity in the
atmosphere.

Temperature Inversion
(surface-based or elevated) : a layer of the atmosphere in which air
temperature increases with height. When the layer's base is at the
surface, the layer is called a surface-based temperature inversion; when
the base of the layer is above the surface, the layer is called an
elevated temperature inversion.

Temperature Recovery
The change in temperature over a given period of time. Generally, the
period between late evening and sunrise. Windy or cloudy conditions will
tend to produce slow temperature recovery, while clear, calm weather can
cause rapid recovery.

TEMPS
temperatures

Terminal Aerodrome Forecast
This NWS aviation product is a concise statement of the expected
meteorological conditions at an airport during a specified period
(usually 24 hours). Each country is allowed to make modifications or
exceptions to the code for use in each particular country. TAFs use the
same weather code found in METAR weather reports.

Terrain Forced Flow
An airflow that is modified or channeled as it passes over or around
mountains or through gaps in a mountain barrier.

Texas Hooker
Same as Panhandle Hook - low pressure systems that originate in the
panhandle region of Texas and Oklahoma which initially move east and
then "hook" or recurve more northeast toward the upper Midwest or Great
Lakes region. In winter, these systems usually deposit heavy snows
north of their surface track. Thunderstorms may be found south of the
track.

Thalweg
In hydrologic terms, the line of maximum depth in a stream. The thalweg
is the part that has the maximum velocity and causes cutbanks and
channel migration.

Theodolite
An instrument used in surveying to measure horizontal and vertical
angles with a small telescope that can move in the horizontal and
vertical planes. It used to track the movements of either a ceiling
balloon or a radiosonde.

Thermal
A relatively small-scale, rising air current produced when the Earth's
surface is heated. Thermals are a common source of low level turbulence
for aircraft.

Thermal Belt
A zone of high nighttime temperatures (and relatively low humidities)
that is often experienced within a narrow altitude range on valley
sidewalls, especially evident during clear weather with light winds.

Thermal High
Area of high pressure that is shallow in vertical extent and produced
primarily by cold surface temperatures.

Thermal Low
Area of low pressure that is shallow in vertical extent and produced
primarily by warm surface temperatures.

Thermal Wind
It is a theoretical wind that blows parallel to the thickness lines,
for the layer considered, analogous to how the geostrophic wind blows
parallel to the height contours. The closer the thickness isopleths,
the stronger the thermal wind. Cold air is always located to the left
of the thermal wind (as you face downstream) and the warm air is
located on the right. Since thickness contours are tighter on the cold
side of thermal wind, your lower thickness values will be found on the
left side of the thermal wind. The speed and direction of the thermal
wind are determined by vector geometry where the geostrophic wind at
the upper level is subtracted from the geostrophic wind at the lower
level.

Thermally Driven Circulation
A diurnally reversing closed cellular wind current resulting from
horizontal temperature contrasts caused by different rates of heating
or cooling over adjacent surfaces; includes along-slope, cross-valley,
along-valley, mountain-plain and sea breeze circulations.

Thermistor
A resistor whose resistance changes with temperature. Because of the
known dependence of resistance on temperature, the resistor can be used
as a temperature sensor.

Thermocline
As one descends from the surface of the ocean, the temperature remains
nearly the same as it was at the surface, but at a certain depth
temperature starts decreasing rapidly with depth. This boundary is
called the thermocline. In studying the tropical Pacific Ocean, the
depth of 20�C water ("the 20�C isotherm") is often used as a proxy for
the depth of the thermocline. Along the equator, the 20�C isotherm is
typically located at about 50 m depth in the eastern Pacific, sloping
downwards to about 150 m in the western Pacific.

Thermodynamic Chart
A chart containing contours of pressure, temperature, moisture, and
potential temperature, all drawn relative to each other such that basic
thermodynamic laws are satisfied. Such a chart typically is used to plot
atmospheric soundings, and to estimate potential changes in temperature,
moisture, etc. if air were displaced vertically from a given level. A
thermodynamic chart thus is a useful tool in diagnosing atmospheric
instability.

Thermodynamic Diagram
Used interchangably with Thermodynamic Chart; a chart containing contours
of pressure, temperature, moisture, and potential temperature, all drawn
relative to each other such that basic thermodynamic laws are satisfied.
Such a chart typically is used to plot atmospheric soundings, and to
estimate potential changes in temperature, moisture, etc. if air were
displaced vertically from a given level. A thermodynamic chart thus is a
useful tool in diagnosing atmospheric instability.

Thermodynamics
In general, the relationships between heat and other properties (such as
temperature, pressure, density, etc.) In forecast discussions,
thermodynamics usually refers to the distribution of temperature and
moisture (both vertical and horizontal) as related to the diagnosis of
atmospheric instability.

Thermograph
An instrument that measures and records air temperature.

Thermometer
An instrument for measuring air temperature.

Thermosphere
The atmospheric shell extending from the top of the mesosphere to outer
space. It is a region of more or less steadily increasing temperature
with height, starting at 70 or 80 km.



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