Subj : Wx Terms (S)(4)
To   : All
From : Daryl Stout
Date : Tue Jun 20 2017 12:08 am

Sky Condition
Used in a forecast to describes the predominant/average sky condition
based upon octants (eighths) of the sky covered by opaque (not
transparent) clouds.

Sky Condition   Cloud Coverage

Clear / Sunny   0/8

Mostly Clear / Mostly Sunny     1/8 to 2/8

Partly Cloudy / Partly Sunny    3/8 to 4/8

Mostly Cloudy / Considerable Cloudiness 5/8 to 7/8

Cloudy  8/8

Fair (mainly for night) Less than 4/10 opaque clouds, no precipitation,
no extremes of visibility/temperature/wind

SKYWARN
A nationwide network of volunteer weather spotters who report to and are
trained by the National Weather Service. These spotters report many forms
of significant or severe weather such as Severe Thunderstorms, Tornadoes,
Hail, Heavy Snow, or Flooding. Contact your local National Weather Service
Forecast Office to learn about SKYWARN activities in your area.

SL
Sea Level

SLD
Solid

Sleet
(PL) - Sleet is defined as pellets of ice composed of frozen or mostly
frozen raindrops or refrozen partially melted snowflakes. These pellets
of ice usually bounce after hitting the ground or other hard surfaces.
Heavy sleet is a relatively rare event defined as an accumulation of
ice pellets covering the ground to a depth of 1" or more.

Sleet Warning
Issued when accumulation of sleet in excess of 1/2" is expected; this is
a relatively rare scenario. Usually issued as a winter storm warning for
heavy sleet.

SLGT
Slight

Slight Chance
In probability of precipitation statements, usually equivalent to a 20
percent chance.

Slight Risk
(of severe thunderstorms)- Severe thunderstorms are expected to affect
between 2 and 5 percent of the area. A slight risk generally implies that
severe weather events are expected to be isolated.

Sling Psychrometer
An instrument used to measure the water vapor content of the atmosphere
in which wet and dry bulb thermometers are mounted on a frame connected
to a handle at one end by means of a bearing or a length of chain. The
psychrometer is whirled by hand to provide the necessary ventilation to
evaporate water from the wet bulb.

SLO
Slow

SLOSH
(Sea, Lake and Overland Surges from Hurricanes) - A computer model run
by the National Hurricane Center (NHC) to estimate storm surge heights
resulting from historical, hypothetical, or predicted hurricanes by
taking into account pressure, size, forward speed, track, and winds.

SLP
Sea Level Pressure

SLT

1. Slight (as in "slight chance")

2. Sleet

SLY
Southerly

SM

1) Statute Miles

2) Sum total for month

SMA
The Soil Moisture Accounting Model.

Small Craft
There is no precise definition for small craft. Any vessel that may be
adversely affected by Small Craft Advisory criteria should be considered
a small craft. Other considerations include the experience of the vessel
operator, and the type, overall size, and sea worthiness of the vessel.
See Small Craft Advisory.

Small Craft Advisory
(SCA) - An advisory issued by coastal and Great Lakes Weather Forecast
Offices (WFO) for areas included in the Coastal Waters Forecast or
Nearshore Marine Forecast (NSH) products. Thresholds governing the
issuance of small craft advisories are specific to geographic areas. A
Small Craft Advisory may also be issued when sea or lake ice exists that
could be hazardous to small boats. There is no precise definition of a
small craft. Any vessel that may be adversely affected by Small Craft
Advisory criteria should be considered a small craft. Other
considerations include the experience of the vessel operator, and the
type, overall size, and sea worthiness of the vessel.

Eastern (ME..SC, Lake Erie, Lake Ontario) - Sustained winds or frequent
gusts ranging between 25 and 33 knots (except 20 to 25 knots, lower
threshold area dependent, to 33 knots for harbors, bays, etc.) and/or
seas or waves 5 to 7 feet and greater, area dependent.

Central (MN..OH) - Sustained winds or frequent gusts (on the Great Lakes)
between 22 and 33 knots inclusive, and/or seas or waves greater than 4 feet.

Southern (GA..TX and Caribbean) - Sustained winds of 20 to 33 knots,
and/or forecast seas 7 feet or greater that are expected for more than 2
hours.

Western (WA..CA) - Sustained winds of 21 to 33 knots, potentially in
combination with wave heights exceeding 10 feet (or wave steepness values
exceeding local thresholds).

Alaska (AK) - Sustained winds or frequent gusts of 23 to 33 knots. A small
craft advisory for rough seas may be issued for sea/wave conditions
deemed locally significant, based on user needs, and should be no lower
than 8 feet.

Hawaii (HI), Samoa - Sustained winds 25 knots or greater and seas 10 feet
or greater.

Guam and the Northern Mariana Islands - Sustained winds 22 to 33 knots
and/or combined seas of 10 feet or more.

"Frequent gusts" are typically long duration conditions (greater than 2
hours).

For a list of NWS Weather Offices by Region, refer to the following
website: http://www.nws.noaa.gov/organization.php

Small Craft Advisory for Hazardous Seas
(SCAHS) - An advisory issued by coastal and Great Lakes Weather Forecast
Offices (WFO). This advisory may be issued within the Coastal Waters
Forecast or Nearshore Marine Forecast products. This advisory may be
issued when wind speeds are lower than small craft advisory criteria,
yet waves or seas are potentially hazardous due to wave period,
steepness, or swell direction. Thresholds governing the issuance of
Small Craft Advisories for Hazardous Seas are specific to geographic
areas.

Eastern (ME..SC, Lake Erie, Lake Ontario) - Seas or waves 5 to 7 feet
and greater, area dependent.

Central (MN..OH) - Seas or waves greater than 4 feet.

Southern (GA..TX and Caribbean) - Seas 7 feet or greater that are
expected for more than 2 hours.

Western (WA..CA) - Seas 10 feet or greater; or wave steepness values
exceeding local criteria.

Alaska (AK) - Seas or wave conditions deemed locally significant, based
on user needs, and should be no lower than 8 feet.

Hawaii (HI), Samoa - Seas 10 feet or greater.

Guam and the Northern Mariana Islands - Combined seas of 10 feet or more.


Small Craft Advisory for Rough Bar
(SCARB): An advisory issued by coastal and Great Lakes Weather Forecast
Offices (WFO) for specialized areas near harbor or river entrances known
as bars. This advisory may be included within the Coastal Waters Forecast
or Nearshore Marine Forecast products. Waves in or near such bars may be
especially hazardous to mariners due to the interaction of swell, tidal
or river currents in relatively shallow water. Thresholds governing the
issuance of Small Craft Advisories for Rough Bar are specific to local
geographic areas, and are based upon parameters such as wave steepness,
wind speed and direction, and local bathymetry.



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