SKYWARN is a national network of volunteer severe weather spotters. The
spotters are trained by local National Weather Forecast Offices on how to
spot severe thunderstorms, tornadoes, hail and flooding. In parts of
the country, spotters also report
snowfall and ice.
SKYWARN History
During the early 1940's the Weather Bureau cooperated with the military in
setting up volunteer spotter networks to protect military installations. After a
tornado killed 80 and injured 273 people in Kansas in 1955,the Weather Bureau
decided to train severe weather spotters. On March 8,1959, in Wellington,
Kansas, the first training course for 225 severe weather spotters was held.
How does
SKYWARN Amateur Radio work?
Two-thirds of the volunteers are licensed amateur radio operators. Amateur
radio plays a big role in the SKYWARN program. During severe weather,
amateur radio volunteers man a amateur radio station
at the National Weather Service Office. They talk to the spotters in the particular area that the storm is occuring and request
information needed by the forecasters. Large storms knock out phone
service. SKYWARN amateur radio volunteers are there to relay severe weather reports to
the national weather offices to keep communities informed of severe weather.
The National Weather Service issues watches and warnings warnings, based in part
on observations from storm spotters in the field. Your reports are important to
warning forecasters who are making critical warning decisions.
How do I become a weather spotter?
You must take a SKYWARN class. This class is a free 3-hour
seminar that teaches you the basics of how SKYWARN
operates, how to spot severe weather, what to report, how to
report and when to report it. At the end of the class, you are given a special SKYWARN ID card with reporting instructions.
There is no cost for the class. SKYWARN
Training classes are
held each spring.
What Spotters Look For
Storm spotters play a
vital role in the warning and information process by observing storms and making
reports back to the National Weather Service and local public safety officials.
Trained spotters learn about the physical structure of severe storms and how to
identify the most likely areas for severe weather development. They also learn
about visual clues that may precede tornado development, and learn to
distinguish between real tornadoes and look-alikes. These types of details, when
coupled with NWS forecasters’ expert radar interpretation, lead to better
warnings and statements. Once SKYWARN
Spotter observation reports are received by the National Weather Service office
via a toll-free 800 number or web email, the reports are sent to the media (i.e.,
Weather Channel, etc..)
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SKYWARN
Reporting Criteria
How to
report
When making a report, remember to answer three basic questions...
WHAT Happened? Type of Event (Tornado, downed trees, etc..)
WHEN did the event happen? Also, duration of the event.
WHERE did the event happen? Location of event (town or city, portion of county, major intersections)
What To Report
Tornadoes
Funnel Clouds and Wall Clouds
Rotating Thunderstorms
Wind Gusts Greater Than 45 mph
Hail (any size)
Wind Damage
Flooding
Heavy Rain
Power
Outages
Any
weather related deaths and injuries
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Spotters Safety Tips
Safety should be
first and foremost on the mind of a spotter. Remember, the N.W.S. values your
safety more than your observations. It is essential that spotters proceed
into the field armed not only with knowledge of the storms but also with an
understanding of the dangers posed by thunderstorms. When spotting, travel in
pairs if at all possible. When moving, this will allow the driver to remain
focused on the chore of driving while the passenger keeps an eye on the sky and
handles any communication with the dispatcher. When stopped, two sets of eyes
are available for observation.
Keep aware of the
local environment at all times. When in the vicinity of a thunderstorm, keep a
2-mile "buffer zone" between you and the storm. Frequently check the
sky overhead and behind to ensure no unexpected events (such as a new tornado)
are developing. Always have an escape route available, in case threatening
weather approaches or if you get within the 2-mile "buffer zone."
Lightning is the
number one killer among weather phenomena. During a typical year, lightning
kills more people than hurricanes, tornadoes, and winter storms combined. The
two main threats posed by lightning are the intense heat of the lightning stroke
(about 15,000 degrees Celsius) and the extreme current associated with the
stroke, estimated at 30,000 amperes (less than 1 ampere can be fatal).
Lightning is also the
biggest weather hazard facing the spotter. When in the field, the spotter will
usually be in a preferred lightning strike area (in the open, on a hilltop,
etc.). Whenever possible, remain in your spotting vehicle to minimize the chance
of being struck by lightning. If you must leave your vehicle, crouch as low as
possible to make yourself a less favorable target. Hail is usually not a direct
threat to life, but hailstorms are the costliest weather element to affect the
United States. Each year, hailstorms cause over $1 billion in damage primarily
to crops, livestock, and roofs. Giant hailstones (2 inches or more in diameter)
can reach speeds of 100 miles an hour as they fall to earth. If such a stone
strikes someone, the results can be fatal. There have been only two documented
hail related deaths in the United States, but a hailstorm in China killed over
100 people in 1976. A vehicle will usually offer adequate protection from
moderate sized hailstones. Hail larger than golf ball size may damage
windshields, so avoid large hail shafts if at all possible.
Down bursts are
underrated thunderstorm threats. A down burst is defined as a strong down draft
with an out rush of damaging winds on or near the earth's surface. Down bursts
are responsible for the "wind shear" which has caused a number of
airliner accidents in the 1970's and early 1980's. When people experience
property damage from a down burst, they often do not believe that "just
wind" could have caused the damage, and they assume that they were struck
by a tornado. In fact, the strongest down bursts have wind gusts to near 130
miles an hour and are capable of the same damage as a medium sized tornado.
Down bursts are
classified based on their size. If the swath of damaging winds is 2.5 miles or
greater, it is called a macroburst. If the swath is less than 2.5 miles across,
it is called a microburst. In general, macrobursts are long-term, large scale
events, while microbursts are intense, quick hitting phenomena. Microbursts are
subdivided as wet or dry microbursts, depending on how much rain falls with the
microburst. If very heavy rain falls with the microburst, it is called a wet
microburst, while a dry microburst has little or no rain reaching the ground.
Flash floods are
another example of an underrated thunderstorm threat. Over the past several
years, more people have been killed in flash floods than in tornadoes. Two
factors are responsible for this. First, we have urbanized. Where rain water
used to have open fields in which to run off, it now has highway intersections,
basements, streets, etc. Second, the public as a whole is apathetic about flash
flooding. We simply do not treat flash flooding with the respect it deserves.
Many of the recent deaths associated with flash flooding have occurred because
people attempted to drive their vehicles across a flooded low water crossing and
were swept away by the flood waters. Less than two feet of moving water is
needed for a vehicle to be swept away. When spotting in a flash flood situation,
follow these common sense safety tips. Remember that flash flooding is most
dangerous at night when the effects of flash flooding are difficult to see.
Since most flash floods occur at night, this problem is compounded. Avoid low
water crossings and don't drive into areas where water covers the road. If you
are caught in a flash flood, abandon your vehicle and quickly get to higher
ground.
Last but not least is
the tornado. Again, a tornado is defined as a violently rotating column of air
in contact with the ground and pendant from a thunderstorm (whether or not a
condensation funnel is visible to the ground). If the violently rotating column
of air has not touched the ground, it is called a funnel cloud. If a tornado is approaching your
location, drive away from the tornado IF you are in open country, IF the
location and motion of the tornado are known, and IF you are familiar with the
local road network. If you are in an urban area and escape is not possible for
some reason, abandon your vehicle and get into a reinforced building. If a
reinforced building is not available, get into a culvert, ditch, or other low
spot in the ground (that is not flooded).
Spotting at night is
obviously more difficult than spotting during the day. There are only a few
allies available to help you when night spotting. If possible, use the light
from lightning flashes to illuminate the important parts of the storm. Quite
often, though, lightning strokes will be very brief and will illuminate
different parts of the storm from different angles. This will make it even more
difficult to accurately report what is occurring. If you are in large hail, the
most dangerous part of the storm is near you and will probably move overhead
within a few minutes. If you hear a loud roaring sound, then a tornado may be
very close to your location. Use this tip with caution. Not all tornadoes have a
loud roar, and some non-tornadic winds may also possess a loud roar. Finally, if
you think there is a tornado not far from your location (i.e., within spotting
range), search along the horizon for bright flashes of light as the tornado
destroys power lines and transformers.
---------------------------------------
What is RACES?
The
Radio Amateur Civil Emergency Service (RACES), is a public service provided by a
reserve volunteer group of Amateur Radio Operators that is administered by
local, county and state emergency management agencies, and supported by the
Federal Emergency Management Agency (FEMA) of the United States government. As a
part of the Amateur Radio Service, it provides radio communications for
civil-preparedness purposes only, during periods of local, regional or national
civil emergencies. These emergencies are not limited to war-related activities,
but can include natural disasters such as earthquakes, hurricanes, wildfires,
power outages, floods, victim searches, air crashes, and many others.
What is ARES?
The Amateur Radio Emergency Service (ARES) consists of licensed amateurs who
have voluntarily registered their qualifications and equipment for
communications duty in the public service when disaster strikes. Every licensed
amateur, regardless of membership in ARRL or any other local or national
organization, is eligible for membership in the ARES. The only qualification,
other than the possession of an Amateur Radio license, is a sincere desire to
serve. Because ARES is an amateur service, only amateurs are eligible for
membership. The possession of emergency-powered equipment is desirable, but is
not a requirement for membership.
The Taunton, Massachusetts National Weather Service has a SKYWARN / ARES
Spotting Program. The amateur radio call is WX1BOX.
SKYWARN Spotters and amateur radio operators send reports to the weather service
ops via phone or radio communication. There are many frequencies where the
SKYWARN weather nets are run. Most are on the 2 meter (144-148 MHz) and 70
centimeter ( 420-450 MHz) bands.
The
Southeast Massachusetts Weather Net Schedule
The
Cape Cod and Islands Weather Net, 146.955 MHz Barnstable
Repeater
Monday-Friday
6:00-6:30 am.
The
Fairhaven Weather Net, 145.490 MHz Fairhaven Repeater
Monday-Friday
8:00-8:30 pm.
The
SKYWARN Rhode Island Weather Net, 146.760 MHz Cranston
Repeater
Wednesday
Evenings at 8:30 pm
The
National Hurricane Net, 14.325 MHz (Upper Side Band)
Seasonal Broadcasts
Amateur Radio Repeater
and NOAA Weather Frequencies
Massachusetts
/ Rhode Island Amateur Radio Repeaters...
Cirrus
clouds are the most common of the high clouds. They are composed of
ice and consist of long, thin, wispy streamers. Cirrus clouds are
usually white and predict fair weather.
Sometimes called mares tails, they stream with the wind. By watching
the movement of cirrus clouds you can tell from which direction
weather is approaching. The appearance of cirrus clouds usually
indicates that a change in weather will occur within 24 hours.
Cirrostratus
are sheet-like, thin clouds that usually cover the entire sky. The
sun or moon can shine through Cirrostratus clouds. Cirrostratus
clouds usually come 12-24 hours before a rain or snow storm.
Cirrocumulus
are small, rounded puffs that usually appear in long rows. They are
usually white, but sometimes appear gray. Cirrocumulus are usually
seen in the winter and indicate fair, but cold, weather. In the
tropics, they may indicate an approaching hurricane.
Medium
high clouds occupy altitudes of 6,500 feet to 18,000 feet
An
Altostratus cloud usually covers the whole sky. The
cloud looks gray or blue-gray. The sun or moon may shine through an
Altostratus cloud, but will appear hazy. An altostratus cloud
usually forms ahead of storms with continuous rain or snow.
Altocumulus
clouds are grayish-white with one part of the cloud darker than the
other. Altocumulus clouds usually form in groups. If you see
Altocumulus clouds on a warm, sticky morning, be prepared for
thunderstorms by late afternoon.
Low
clouds, called stratus clouds, are at altitudes up to 6,500 feet
Stratus
clouds are uniform gray in color and almost cover the entire sky.
Light mist or drizzle is sometimes associated with Stratus clouds. A
Stratus cloud touching the ground is fog.
Stratocumulus
clouds are low, puffy and gray. Most form in rows with blue sky
visible in between. Rain rarely occurs with Stratocumulus clouds,
however, they can turn into Nimbostratus.
Nimbostratus
clouds are dark gray with a ragged base. Rain or snow is associated
with Nimbostratus clouds.
Clouds
with vertical growth
Vertically
developing clouds are the Cumulus (puffy) type.
These small, lumpy clouds are low "fair weather" clouds.
However, as they develop vertically (up) they may go from small,
fair weather clouds to large, boiling, vertically-growing monsters
called cumulonimbus.
Cumulonimbus
are generally known as thunderstorm clouds. High winds will flatten
the top of the cloud into an anvil-like shape. Cumulonimbus are
associated with heavy rain, snow, hail, lightning, and tornadoes.
The anvil usually points in the direction the storm is moving.
Thunderstorms
Thunderstorms are
common in this part of the world, and most of us are quite familiar with them
and the dangerous weather they can bring. Most individual thunderstorms only
last several minutes, however some individual thunderstorms become very
well-organized and can last several hours. These long-lived thunderstorms are
called supercell thunderstorms. Supercell thunderstorms are responsible for the
majority of significant severe weather, including very large hail and tornadoes.
However, storms that form in organized lines (called squall lines) can also
produce widespread strong and damaging winds.
Thunderstorm
movement left to right.
What is a Severe Thunderstorm?
A severe
thunderstorm is defined by the National Weather Service as one that produces one
or more of the following:
Hail ¾ of an inch in diameter (roughly the
size of a dime)
Wind gusts of 58 mph (50 knots) or higher
Wind or hail damage
A tornado
Thunderstorm
Life Cycle
The Developing
Stage...
The
Mature Stage
Disapating
Stage
What is a
Downburst?
A downburst is
defined as a strong downdraft from a thunderstorm with an outrush of damaging
wind on or near the ground. Damaging downburst, although relatively rare, are
much more common than tornadoes. Because of their small size and short lifespan,
it is difficult to detect and warn for downbursts. Many confuse damage produced
by "straight-line" winds and often erroneously attribute it to
tornadoes. Wind speeds can reach up to 100 mph (161 km/h) with a damage path
extending from hundreds of miles. Downbursts are divided into two categories.
Macroburst-Swath of
damaging wind is 2.5 miles or more wide.
Microburst-Swath of
damaging wind is less that 2.5 miles wide.
Tornadoes
In a
typical year about 1000 tornados will strike the United States. The peak of the
tornado season is April through June and more tornadoes strike the central
United States than any other place in the world. This area has been nicknamed
"tornado alley." Most tornados are spawned from supercell
thunderstorms.
Here are
my photos taken of the May 15, 2009 F2 Tornado in
Kirksville, Missouri...
and the
outflow of a 100 mile wide supercell in Garnett, Kansas
on May 17,2009...
Supercell
thunderstorms are characterized by a persistent rotating updraft and form in
environments of strong vertical wind shear. Wind shear is the change in wind
speed and/or direction with height. The updraft lifts the rotating column of air
created by the speed shear. This provides two different rotations to the
supercell; cyclonic or counter clockwise rotation and an anti-cyclonic of
clockwise rotation.
When
viewed from the top, the counter-clockwise rotation of the mesocyclone gives the
supercell its classic "hook" appearence when seen by radar. As the air
rises in the storm, it becomes stretched and more narrow with time.
Lightning
Thunderstorms have very
turbulent environments. Strong updrafts and downdrafts occur closely to each
other. The updrafts transport small liquid water droplets from the lower regions
of the storm to heights between 35,000 and 70,000 feet, miles above the freezing
level. Downdrafts transport hail and ice from the frozen upper regions of the
storm. When these collide, the water droplets freeze and release heat. This heat
in turn keeps the surface of the hail and ice slightly warmer than its
surrounding environment and small hail
forms. It is believed that precipitation collides with each other causing an
electrical discharge in the thunderstorm, known as lightning.
Image 1 - The atmosphere
is a very good insulator that inhibits electric flow, a high amount of charge
has to build up before lightning can occur. A
moving thunderstorm gathers another pool of positively charged particles along
the ground that travel with the storm. As the differences in charges continue to
increase, positively charged particles rise up taller objects such as trees,
houses, and telephone poles.
Image 2 - A channel of negative
charge, called a "stepped leader" will descend from the bottom of the
storm toward the ground . It is invisible to the human eye, and shoots to the
ground in a series of rapid steps, each occurring in less time than it takes to
blink your eye. As the negative leader approaches the ground, positive charge
collects in the ground and in objects on the ground.
Image 3 - This positive charge
"reaches" out to the approaching negative charge with its own channel,
called a "streamer" . When these channels connect, the resulting
electrical transfer is what we see as lightning. After the initial lightning
stroke, if enough charge is leftover, additional lightning strokes will use the
same channel and will give the bolt its flickering appearance.
Hail
Hail is
precipitation that is formed when updrafts in thunderstorms carry raindrops
upward into extremely cold areas of the atmosphere. Hail can damage aircraft,
homes and cars, and can be deadly to livestock and people. One of the people
killed during the March 28, 2000 tornado in Fort Worth was killed when struck by
grapefruit-size hail.
The hail nucleus, buoyed by the updraft is
carried aloft by the updraft and begins to grow in size as it collides with
supercool raindrops and other small pieces of hail.
Sometimes the hailstone is blown out of the main
updraft and begins to falls to the earth.
If the updraft is strong enough it will move
the hailstone back into the cloud where it once again collides with water and
hail and grows. This process may be repeated several times.
In all cases, when the hailstone can no
longer be supported by the updraft it falls to the earth. The stronger the
updraft, the larger the hailstones that can be produced by the thunderstorm.
Spotter Weather Terms
ANVIL
The top
portion of a mature thunderstorm that has the appearance of having been
"blown off".
ARC CLOUD
Also sometimes
called a shelf cloud. This is usually the dark, ominous looking cloud
formation the precedes the passage of a squall line or multicell thunderstorm
formation. It is formed as warm moist air overrides cool downdraft winds at
the leading edge of the thunderstorm (the gust front).
CELL
The basic
thunderstorm, which consists of one updraft and one downdraft.
DEBRIS CLOUD
Area of dust,
sand, and debris that forms near the ground at the base of a tornado.
DOWNBURST
A small area of
rapidly descending air beneath a thunderstorm. Downburst winds hit the ground
and spread out, often at speeds in excess of 100 mph. See also downdraft,
macroburst and microburst.
DOWNDRAFT
Area within a
thunderstorm where the predominant air motion is downward. Where there is
precipitation there will always be a downdraft. Downbursts are localized areas
within the downdraft of very rapidly descending air.
FUNNEL (CLOUD)
Generally the
funnel is a visible tornado that hasn’t yet reached the ground. Funnels
consist of water droplets that have condensed due to the rapid temperature and
pressure changes in the vicinity. Also called condensation funnel.
GUST FRONT
The area near
the leading edge of a thunderstorm where downdraft winds hit the earth’s
surface and spread out. The gust front is the leading edge of the spreading
winds. The gust front is usually found just below or very near the arc cloud.
HAIL
Large ice
chunks that grow within the thunderstorm until they are too heavy to be
supported by the mechanics within the storm. Large hailstones fall at speeds
greater than 100 mph.
INFLOW
Area of a
thunderstorm where air from the surrounding environment is "sucked
up" into the thunderstorm updraft. The inflow area is always void of
precipitation and the cloud bases are dark and flat.
MACROBURST
A downburst
with a diameter of greater than 2.5 miles.
MAMMATUS
Downward
protruding "bumps" usually on the underside of the anvil of a
thunderstorm. Mammatus ("Mama") clouds are indicative of extreme
turbulence.
MICROBURST
A downburst
with a diameter of 2.5 miles or less.
OUTFLOW
That portion of
the thunderstorm where the downdraft winds hit the surface of the earth and
spread out.
OVERSHOOTING
TOP
A protruding
cloud area above the usually smooth anvil of a mature thunderstorm that
indicates the presence of an intense updraft.
RAIN-FREE
BASE
A dark, horizontal cloud base with no visible
precipitation beneath it. The rain-free base typically marks the location of
the thunderstorm updraft. Tornadoes may develop from wall clouds attached to
the rain-free base, or from the rain-free base itself - especially when the
rain-free base is on the south or southwest side of the main precipitation
area. Note that the rain-free base may not actually be rain free; hail or
large rain drops may be falling. For this reason, updraft base is more
accurate.
SCUD (CLOUD)
Clouds that
appear to have broken off beneath the base of a thunderstorm. Scud (fractus)
clouds often may reach to near the ground and can be easily mistaken for a
funnel.
SHELF CLOUD
See Arc Cloud.
TAIL CLOUD
Scud-type cloud
that forms near the base of a wall cloud and protrudes almost parallel to the
earth toward the main precipitation shaft of the thunderstorm.
TORNADO
Rotating area
of strong winds and rapid pressure change that sometimes forms in conjunction
with a severe thunderstorm.
UPDRAFT
The area within
the thunderstorm where the predominant air motion is upward.
VAULT
An area of dry
clear air that often forms between the main precipitation shaft and the
rain-free base wall cloud.
WALL CLOUD
A rotating
cloud that forms beneath the base of the thunderstorm behind the main
precipitation shaft where some of the inflowing air and outflowing air meet
and mix. Tornadoes, if they occur, will appear to drop out of the wall cloud.
WATERSPOUT
A weak tornado
that forms over warm water. The formation mechanisms for waterspouts are
different from those of land tornadoes, and waterspouts may form during
relatively calm-looking weather
WHAT Happened? Type of Event (Tornado, downed trees, etc..)
