Subj : Wx Terms (S)(7)
To   : All
From : Daryl Stout
Date : Fri Oct 20 2017 12:05 am

Sphere Calibration
Reflectivity calibration of a radar by pointing the dish at a metal
sphere of (theoretically) known reflectivity. The sphere is often
tethered to a balloon.

Spillway
In hydrologic terms, a structure over or through which excess or flood
flows are discharged. If the flow is controlled by gates, it is a
controlled spillway, if the elevation of the spillway crest is the only
control, it is an uncontrolled spillway.

Spillway Crest
In hydrologic terms, the elevation of the highest point of a spillway.

Spin-Up
Slang for a small-scale vortex initiation, such as what may be seen when
a gustnado, landspout, or suction vortex forms.

SPKL
Sprinkle

Split Flow
A flow pattern high in the atmosphere characterized by diverging winds.
Storms moving along in this type of flow pattern usually weaken.

Splitting Storm
A thunderstorm which splits into two storms which follow diverging paths
(a left mover and a right mover). The left mover typically moves faster
than the original storm, the right mover, slower. Of the two, the left
mover is most likely to weaken and dissipate (but on rare occasions can
become a very severe anticyclonic-rotating storm), while the right mover
is the one most likely to reach supercell status.

SPLNS
Southern Plains

Sporadic E
In solar-terrestrial terms, a phenomenon occurring in the E region of the
ionosphere, which significantly affects HF radiowave propagation.
Sporadic E can occur during daytime or nighttime and it varies markedly
with latitude.

SPOTNIL
In solar-terrestrial terms, a spotless disk.

Spotting
Outbreak of secondary fires as firebrands or other burning materials are
carried ahead of the main fire line by winds.

Spray
An ensemble of water droplets torn by the wind from an extensive body of
water, generally from the crests of waves, and carried up into the air in
such quantities that it reduces the horizontal visibility.

SPRD
Spread

Spring

1. The season of the year comprising the transition period from winter to
summer occurring when the sun is approaching the summer solstice. In the
Northern Hemisphere, spring customarily includes the months of March,
April and May.

2. In hydrologic terms, an issue of water from the earth; a natural
fountain; a source of a reservoir of water.

Spring Tide
A tide higher than normal which occurs around the time of the new and
full moon.

SPS
Severe Weather Potential Statement

SQLN
Squall Line

Squall

1. A strong wind characterized by a sudden onset, a duration of the order
of minutes, and then a rather sudden decrease in speed. In U.S.
observational practice, a squall is reported only if a wind speed of 16
knots or higher is sustained for at least two minutes (thereby
distinguishing it from a gust).

2. In nautical use, a severe local storm considered as a whole, that is,
winds and cloud mass and (if any) precipitation, thunder and lightning.

Squall Line
A line of active thunderstorms, either continuous or with breaks,
including contiguous precipitation areas resulting from the existence of
the thunderstorms.

SRF
(Surf Zone Forecast) - A National Weather Service routine or event driven
forecast product geared toward non-boating marine users issued for an
area extending from the area of water between the high tide level on the
beach and the seaward side of the breaking waves.

SRH
Storm-Relative Helicity

SRN
Southern

SS
Sandstorm

SSHS
Saffir/Simpson Hurricane Scale

SST
Sea Surface Temperature

ST
Stratus

St Lawrence Freeze-Up Outlook
A National Weather Service forecast product to keep mariners informed of
the projected freeze-up date of ice the St. Lawrence River.

St. Elmo's Fire
The glow on a masthead produced by an extreme buildup of electrical
charge. Unprotected mariners should immediately move to shelter when this
phenomena occurs. Lightning may strike the mast within five minutes after
it begins to glow.

Stability
The degree of resistance of a layer of air to vertical motion.

Stability Index
The overall stability or instability of a sounding is sometimes
conveniently expressed in the form of a single numerical value. Used alone,
it can be quite misleading, and at times, is apt to be worthless. The
greatest value of an index lies in alerting the forecaster to those
soundings which should be examined more closely.

Stable
An atmospheric state with warm air above cold air which inhibits the
vertical movement of air.

Stable Boundary Layer
The stably-stratified layer that forms at the surface and grows upward,
usually at night or in winter, as heat is extracted from the atmosphere's
base in response to longwave radiative heat loss from the ground. Stable
boundary layers can also form when warm air is advected over a cold
surface or over melting ice.

Stable Core
Post-sunrise, elevated remnant of the temperature inversion that has
built up overnight within a valley.

Staccato Lightning
A Cloud to Ground (CG) lightning discharge which appears as a single
very bright, short-duration stroke, often with considerable branching.

Stage
The level of the water surface of a river or stream above an established
datum at a given location.

Stair Stepping
In hydrologic terms, the process of continually updating river forecasts
for the purpose of incorporating the effects rain that has fallen since
the previous forecast was prepared.

Standard Atmosphere
A hypothetical vertical distribution of atmospheric temperature,
pressure, and density that, by international agreement, is taken to be
representative of the atmosphere for purposes of pressure altimeter
calibrations, aircraft performance calculations, aircraft and missile
design, ballistic tables, etc.

Standard Synoptic Times
The times of 0000, 0600, 1200, and 1800 UTC. Also known as the main
synoptic times.

State Forecast Product
This National Weather Service product is intended to give a good general
picture of what weather may be expected in the state during the next 5
days. The first 2 days of the forecast is much more specific than the
last 3 days. In comparison with the Zone Forecast Product, this product
will be much more general.

State Weather Roundup
This is a National Weather Service tabular product which provides
routine hourly observations within the state through the National Weather
Wire Service (NWWS). It gives the current weather condition in one word
(cloudy, rain, snow, fog, etc.), the temperature and dew point in
Fahrenheit, the relative humidity, wind speed and direction, and finally
additional information (wind chill, heat index, a secondary weather
condition). These reports are broken up regionally. When the
complementary satellite product is not available, reports from
unaugmented ASOS stations will report "fair" in the sky/weather column
when there are few or no clouds (i.e., scattered or less) below 12,000
feet with no significant weather and/or obstructions to visibility.

Station ID
Five-digit WMO Station Identifier used by the Buoy Data Center since
1976. ID's can be reassigned to future deployments within the same 1
degree square.



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