Subj : Wx Terms (S)(10)
To   : All
From : Daryl Stout
Date : Tue Jun 20 2017 12:09 am

Sunspot Group Classification

A: A small single unipolar sunspot or very small group of spots without
penumbra.

B: Bipolar sunspot group with no penumbra.

C: An elongated bipolar sunspot group. One sunspot must have penumbra.

D: An elongated bipolar sunspot group with penumbra on both ends of the
group.

E: An elongated bipolar sunspot group with penumbra on both ends.
Longitudinal extent of penumbra exceeds 10 deg. but not 15 deg.

F: An elongated bipolar sunspot group with penumbra on both ends.
Longitudinal extent of penumbra exceeds 15 deg.

H: A unipolar sunspot group with penumbra.


Sunspot Number
In solar-terrestrial terms, a daily index of sunspot activity (R),
defined as R = k (10 g + s) where S = number of individual spots,
g = number of sunspot groups, and k is an observatory factor.

Super Typhoon
Typhoon having maximum sustained winds of 130 knots (150 mph) or greater.

Supercell
Short reference to Supercell Thunderstorm; potentially the most
dangerous of the convective storm types. Storms possessing this
structure have been observed to generate the vast majority of
long-lived strong and violent (F2-F5) tornadoes, as well as downburst
damage and large hail. It is defined as a thunderstorm consisting of
one quasi-steady to rotating updraft which may exist for several hours.

Supercell Thunderstorm
Potentially the most dangerous of the convective storm types. Storms
possessing this structure have been observed to generate the vast
majority of long-lived strong and violent (F2-F5) tornadoes, as well as
downburst damage and large hail. It is defined as a thunderstorm
consisting of one quasi-steady to rotating updraft which may exist for
several hours. Supercells usually move to the right of the mean wind.
These are called "Right Movers" and they are favored with veering winds.
Occasionally, these thunderstorms will move to the left of the mean
wind. These thunderstorms are called "Left Movers". These supercells
typically don't last as long as their "Right Mover" cousins and they
usually only produce large hail (greater than 3/4 inch in diameter) and
severe wind gusts in the excess of 58 miles an hour. Left Movers are
favored when you have backing winds.

Radar will observe essentially one long-lived cell, but small
perturbations to the cell structure may be evident. The stronger the
updraft, the better the chance that the supercell will produce severe
(hail greater than 3/4 inch in diameter, wind gusts greater than 58
miles an hour, and possibly a tornado) weather.

Severe supercell development is most likely in an environment possessing
great buoyancy (CAPE) and large vertical wind shear. A Bulk Richardson
Number of between 15 and 35 favor supercell development. Typically, the
hodograph will look like a horse shoe. This is due to the wind speed
increasing rapidly with height and the wind direction either veering or
backing rapidly with height.

Supercool
To cool a liquid below its freezing point without solidification or
crystallization.

Supercooled Liquid Water
In the atmosphere, liquid water can survive at temperatures colder than
0 degrees Celsius; many vigorous storms contain large amounts of
supercooled liquid water at cold temperatures. Important in the
formation of graupel and hail.

Superrefraction
Bending of the radar beam in the vertical which is greater than
sub-standard refractive conditions. This causes the beam to be lower
than indicated, and often results in extensive ground clutter as well
as an overestimation of cloud top heights.

Surcharge Capacity
In hydrologic terms, the volume of a reservoir between the maximum
water surface elevation for which the dam is designed and the crest of
an uncontrolled spillway, or the normal full-pool elevation of the
reservoir with the crest gates in the normal closed position.

Surf Zone
Area of water between the high tide level on the beach and the seaward
side of the breaking waves.

Surf Zone Forecast
(SRF) - 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.

Surface Energy Budget
The energy or heat budget at the earth's surface, considered in terms
of the fluxes through a plane at the earth-atmosphere interface. The
energy budget includes radiative, sensible, latent and ground heat
fluxes.

Surface impoundment
In hydrologic terms, an indented area in the land's surface, such as a
pit, pond, or lagoon.

Surface Runoff
In hydrologic terms, the runoff that travels overland to the stream
channel. Rain that falls on the stream channel is often lumped with this
quantity.

Surface Water
Water that flows in streams and rivers and in natural lakes, in
wetlands, and in reservoirs constructed by humans.

Surface Weather Chart
An analyzed synoptic chart of surface weather observations. A surface
chart shows the distribution of sea-level pressure (therefore, the
position of highs, lows, ridges and troughs) and the location and nature
of fronts and air masses. Often added to this are symbols for occurring
weather phenomena. Although the pressure is referred to mean sea level,
all other elements on this chart are presented as they occur at the
surface point of observation.

Surface-based Convection
Convection occurring within a surface-based layer, i.e., a layer in which
the lowest portion is based at or very near the earth's surface. Compare
with elevated convection.

Surge
In solar-terrestrial terms, a jet of material from active regions that
reaches coronal heights and then either fades or returns into the
chromosphere along the trajectory of ascent.

Sustained Overdraft
In hydrologic terms, long-term withdrawal from the aquifer of more water
than is being recharged.

Sustained Wind
Wind speed determined by averaging observed values over a two-minute
period.

SVR

1. Severe

2. Abbreviation for Severe Thunderstorm Warning

SVRL
Several

SW

1. Southwest

2. Snow Showers

SWD
On a buoy report, Swell Direction is the compass direction from which the
swell wave are coming from.

SWE
Snow Water Equivalent (the amount of water content in a snowpack or
snowfall).

SWEAT
Severe Weather ThrEAT index; a stability index developed by the Air Force
which incorporates instability, wind shear, and wind speeds as
follows:

SWEAT=(12 Td 850 ) + (20 [TT-49]) +( 2 f 850) + f 500 + (125 [s+0.2])
where

Td 850 is the dew point temperature at 850 mb,

TT is the total-totals index,

f 850 is the 850-mb wind speed (in knots),

f 500 is the 500-mb wind speed (in knots), and

s is the sine of the angle between the wind directions at 500 mb and 850 mb
(thus representing the directional shear in this layer).

SWEAT values of about 250-300 or more indicate a greater potential for
severe weather, but as with all stability indices, there are no magic
numbers.

The SWEAT index has the advantage (and disadvantage) of using only
mandatory-level data (i.e., 500 mb and 850 mb), but has fallen into
relative disuse with the advent of more detailed upper air sounding
analysis programs.

Swell
Wind-generated waves that have travelled out of their generating area.
Swells characteristically exhibit smoother, more regular and uniform
crests and a longer period than wind waves.



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