Subj : Wx Terms (P)(6)
To : All
From : Daryl Stout
Date : Sat Jun 17 2017 09:00 am
PTCHY
Patchy
PTCLDY
Partly Cloudy
PTDY
On a buoy report, Pressure Tendency is the sign (plus or minus) and the
amount of pressure change (hPa) for a three hour period ending at the
time of observation.
PTLY
Partly
PTN
Portion
PTTN
pattern
PTWC
(Pacific Tsunami Warning Center) - The Pacific Tsunami Warning Center in
Ewa Beach (pronounced Eva Beach), HI has an international warning
responsibility for the entire Pacific and a regional warning
responsibility for the State of Hawaii. See also WC/ATWC.
PTYPE
precipitation type
Public Information Statement
A narrative statement issued by a National Weather Service Forecast
Office that can be used for:
1) A current or expected nonhazardous event of general interest to the
public that can usually be covered with a single message (e.g.,
unusual atmospheric phenomena such as sun dogs, halos, rainbows, aurora
borealis, lenticular clouds, and stories about a long-term
dry/cold/wet/warm spell).
2) Public educational information and activities, such as storm safety
rules, awareness activities, storm drills, etc.
3) Information regarding service changes, service limitations,
interruptions due to reduced or lost power or equipment outages, or
special information clarifying interpretation of NWS data. For example,
this product may be used to inform users of radar equipment outages or
special information clarifying interpretation of radar data originating
from an unusual source which may be mistaken for precipitation (such as
chaff drops, smoke plumes, etc., that produces echoes on the radar
display.
Public Severe Weather Outlook
These are issued when the Storm Prediction Center (SPC) in Norman,
Oklahoma anticipates an especially significant and/or widespread outbreak
of severe weather. This outlook will stress the seriousness of the
situation, defines the threat area, and provides information on the
timing of the outbreak. The lead time on this outlook is normally less
than 36 hours prior to the severe weather event.
Puddle
In hydrologic terms,
(1) The act of compacting earth, soil clay, etc., by mixing them with
water and rolling or tamping the mixture.
(2) A compact mass of earth, soil, clay, or a mixture of material,
which has been compacted through the addition of water, rolling and
tamping. This makes the material less permeable.
(3) A small pool of water, usually a few inches in depth and from several
inches to several feet in it greatest dimension.
Puget Sound Convergence Zone
A situation where wind forced around the Olympic Mountains converges over
the Puget Sound. Causes extreme variability in weather conditions around
Seattle, Washington with some areas of sunshine and others in clouds and
rain.
Pulse
A short burst of electromagnetic energy that a radar sends out in a
straight line to detect a precipitation target. The straight line that
this pulse travels along is called a radar beam.
Pulse Duration
The time over which a radar pulse lasts. The pulse duration can be
multiplied by the speed of light to determine the pulse length or pulse
width.
Pulse Length
The linear distance in range occupied by an individual pulse from a
radar. h = c * t , where t is the duration of the transmitted pulse,
c is the speed of light, h is the length of the pulse in space.
Note, in the radar equation, the length h/2 is actually used for
calculating pulse volume because we are only interested in signals
that arrive back at the radar simultaneously. This is also called a
pulse width.
Pulse Radar
A type of radar, designed to facilitate range (distance) measurements,
in which are transmitted energy emitted in periodic, brief transmission.
Pulse Repetition Frequency (PRF)
The amount of time between successive pulses, or bursts, of
electromagnetic energy that is transmitted by a radar. The PRF
determines the maximum range at which echoes can be detected and also
the maximum radial velocity that can be detected by a Doppler radar.
Pulse Repetition Time (PRT)
The time elapsed between pulses by the radar. This is also called the
pulse interval.
Pulse Resolution Volume
A discrete radar sampling volume, of dimensions (horizontal beamwidth *
vertical beamwidth * 1 range gate).
Pulse Severe Thunderstorms
Single cell thunderstorms which produce brief periods of severe weather
(3/4 inch hail, wind gusts in the excess of 58 miles an hour, or a
tornado).
Pulse Storm
A thunderstorm within which a brief period (pulse) of strong updraft
occurs, during and immediately after which the storm produces a short
episode of severe weather. These storms generally are not tornado
producers, but often produce large hail and/or damaging winds. See also
overshooting top.
Pulse Width
Same as Pulse Length; the linear distance in range occupied by an
individual pulse from a radar. h = c * t , where t is the duration of
the transmitted pulse, c is the speed of light, h is the length of the
pulse in space. Note, in the radar equation, the length h/2 is actually
used for calculating pulse volume because we are only interested in
signals that arrive back at the radar simultaneously.
Pulse-Pair Processing
Nickname for the technique of mean velocity estimation by calculation
of the signal complex covariance argument. The calculation requires two
consecutive pulses, hence "pulse-pair".
PVA
Positive Vorticity Advection - the advection of higher values of
vorticity into an area.
PVL
Prevail
PW
Precipitable Water - measure of the depth of liquid water at the surface
that would result after precipitating all of the water vapor in a
vertical column over a given location, usually extending from the
surface to 300 mb.
PWAT
Precipitable Water - measure of the depth of liquid water at the surface
that would result after precipitating all of the water vapor in a
vertical column over a given location, usually extending from the
surface to 300 mb.
PWO
Public Severe Weather Outlook
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