| Safety Precautions!
When acting as a spotter, always remember
that your safety is most important. During a thunderstorm with lightning, stay in
your covered vehicle with the windows up and door shut.
Do not try to outrun a tornado
in your car. Get out of your car and curl up into a ball in a ditch or ravine in a
location that will be as free of flying debris as you can, but be aware of localized
flooding. Keep your head covered and eyes closed.
Above all else, use common sense and
don’t take unnecessary risks.
NEVER Place Yourself In Any
Danger
When Reporting Severe Weather!
Please include the following items in all SKYWARN
reports:
WHAT:Describe event.
WHERE: Direction, and distance from known location, plus movement, and
speed of condition being observed.
WHEN: EXACT time of event.
BY WHOM: Spotter name
(plus callsign if Ham radio operator), and location.
WHAT TO REPORT
ONLY REPORT
OBSERVATIONS,
NOT INTERPRETATIONS!!!
Funnel clouds
Tornadoes
Wall clouds (confirmed or suspected)
Mama clouds
Roll clouds
Shelf clouds
Waterspouts
Report ANY KIND of thunderstorm activity during
the winter months.
Report time of observation
- Location
Direction of motion
- Downburst Winds
- Wind damage to buildings
- Wind damage to trees (large limbs broken off)
- Wind speeds of 35 mph or greater
In non-thunderstorm events... report winds in excess of
50 mph or greater.
- Report time of observation
- Location
- Estimated wind speed
- Estimated wind direction
- Hailstones of any size (initial report).
- Report time of observation
- Location
Size of hailstones -- Measure if possible, report largest size, most common size, and depth of
coverage.For size reference use
pea, marble, dime, quarter, golfball, baseball, softball.
.
.
.
.
- Lightning strikes to people
- Lightning strikes to animals
- Lightning strikes causing building damage
- Report time of strike
- Location
- What was struck
- If a person was struck, report what person was doing,
age, & sex
- Flooded streets
- Standing water in buildings
- Water over the banks of creeks and streams
- Rainfall rates of 3 inches per hour or greater...
and any rainfall totals at the end of a storm event.
- Report time of observation
- Location
- Depth of standing water (if possible)
- Actual rainfall rate (if possible)
SNOW - Report three (3) inches of snow or
snow falling at the rate of one (1) inch per hour.
ICING - Report glazing of roads and attempt
to measure how thick the ice accumulation is where appropriate... along with any damage
reports.
ANY other pertinent reports that may be
regarded as a threat to life and property, including power outages.
Always record and
report
the time of your observation
Always identify
yourself
The GENERAL PUBLIC should
contact their local law enforcement agency during times of severe weather, NOT the
National Weather Service.
Notes:
When spotting for wall clouds, funnel
clouds, tornadoes, and waterspouts the key is always to look for
rotation! Often, scud clouds are mistaken for funnels or tornadoes because they may
form beneath the parent thunderstorm and appear to touch the ground. Just remember... with
scud there will be no rotation.
When estimating wind speed feel free
to use the Beaufort Wind Scale provided in this guide (condensed below). Study the
description of the Effects Observed and choose the appropriate wind speed range from the
table. Report the speed in miles per hour or in knots. DO NOT REPORT THE BEAUFORT
FORCE NUMBER. This will likely send the meteorologists at the National Weather
Service scurrying for reference books, wasting valuable time.
ESTIMATING WIND SPEED
25-31 - Large branches moving. Whistling
in overhead wires.
32-38 - Whole trees moving. Inconvenience walking against wind.
39-46 - Small branches (twigs) break. Impedes walking.
46-54 - Slight structural damage. Larger branches, and weak limbs may break.
55-63 - Moderate structural and tree damage.
64 and above - Heavy to severe tree, and structural damage.
When reporting wind direction remember
that meteorologists always do things backwards. The wind direction reported is ALWAYS
the direction from which the wind is blowing. For example, if you report
the winds as Southerly at 10 mph, that means the winds are coming from the south
blowing to the north.
When reporting hail, use the common
references that are used by the National Weather Service. That is, describe them as pea-sized
(1/4 inch), marble-sized (1/2 inch), dime-sized (3/4 inch), quarter-sized (1 inch),
golfball-sized (1 3/4 inch), baseball-sized (2 3/4 inch) (arggghhhh... let’s hope
you never have to report that)!!!
When assessing wind damage, remember
that most wind damage is done by straight-line winds, not by tornadoes. With
straight-line wind damage, all the damage will look like it diverges (moves outwards) from
a single point possibly in several directions. With tornado damage, destruction is
generally along one direction, debris along the ground is twisted or has spiral
characteristics, and often small arcs where the top-soil has been removed are visible.
If a person is struck by lightning
take appropriate action to ensure immediate aid is given. A person retains no
electrical charge after being struck, so it is safe to touch that person. This
means CPR can be administered immediately if necessary.
SPOTTER RULES AND CLUES
1. Always have a safe place nearby to
protect yourself from wind and/or hail.
2. Cars are a safe place from lightning, but NOT from
tornadoes.
3. Moving water is powerful, it only
takes a slight current to push a vehicle off the road.
4. Large hail often falls just in advance of a tornado,
especially large ones.
5. Tornadoes generally move toward the NORTHEAST at 25 to 35
MPH when associated with fronts, and squall lines but CAN travel at 70 MPH.
6. The first gust of wind to reach you from a thunderstorm
is frequently the strongest.
7. WALL CLOUDS formon the rain free base often 15 to 20 minutes before the
tornado occurs.
8. A rain free base denotes the
storm's updraft area, a place to watch closely.
9. Overshooting tops are an indicator of a very strong
storm.
TORNADOES usually form in the trailing edge of a
thunderstorm. Wind speeds can reach 300 MPH in "MAXI" TORNADOES. Conventional
radar can't see a tornado... it only sees the rain, and hail.
Direct Reporting to NSSL in Project Verify
Thanks to the Internet you can participate in Project Verify (NSSL
Severe Weather Reports Database). To help NWS/NSSL fine tune the 88D radars they need
information about Tornadoes, Hail, Thunderstorm Winds and Thunderstorms. For more
information click here.
The
Spotter’s Observation Kit
Consider keeping the following
equipment handy:
Weather radio (It’s
nice to be able to keep up with weather warnings.)
Communications radio for
reporting your observations (When you see severe weather, you’ve got to report it!)
Raincoat with hood (Stay
dry!)
Flashlight (In case you
can’t see when it gets dark!)
Binoculars (So you can
tell whether that cloud is really rotating!)
Camera or Camcorder (So
that a permanent record can be made of your observations. Pictures and video are the BEST
form of training for other spotters.)
Compass (For estimating
the wind direction -- remember...that’s the direction the wind is coming from!)
Your SKYWARN Observer’s
Guide (So you can remember all this stuff!)
Some
Meteorological 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.
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
| BEAUFORT WIND SCALE |
Beaufort
Force |
Wind Speed |
NWS
Description |
Effects Observed
On Land |
Effects Observed
At Sea |
mph |
knots |
0 |
< 1 |
< 1 |
Calm |
Calm;
smoke rises vertically |
Sea
like mirror |
1 |
1 - 3 |
1 - 3 |
Light
air |
Direction
of wind shown by smoke drift, but not by wind vanes |
Ripples
with scaly appearance; no foam crests |
2 |
4 - 7 |
4 - 6 |
Light
breeze |
Wind
felt on face; leaves rustle; ordinary vane moved by wind |
Small
wavelets, crests of glassy appearance and not breaking |
3 |
8 - 12 |
7 - 10 |
Gentle
breeze |
Leaves
and small twigs in constant motion; wind extends light flag |
Large
wavelets with crests beginning to break, scattered whitecaps |
4 |
13 - 18 |
11 - 16 |
Moderate
breeze |
Raises
dust and loose paper; small branches are moved |
Small
waves growing larger, numerous whitecaps |
5 |
19 - 24 |
17 - 21 |
Fresh
breeze |
Small
trees in leaf begin to sway; crested wavelets form on inland waters |
Moderate
waves with greater length, many whitecaps with some spray |
6 |
25 - 31 |
22 - 27 |
Strong
breeze |
Large
branches in motion; whistling heard in telegraph wires; umbrellas used with difficulty |
Larger
waves, whitecaps very numerous, more spray |
7 |
32 - 38 |
28 - 33 |
Near
gale |
Whole
trees in motion; resistance felt in walking against wind |
Sea
tends to heap up, streaks of foam blown from breaking waves |
8 |
39 - 46 |
34 - 40 |
Gale |
Breaks
twigs off trees; generally impedes progress |
Fairly
high waves of greater length, well-marked streaks of foam |
9 |
47 - 54 |
41 - 47 |
Strong
gale |
Slight
structural damage occurs (chimney pots and slate removed) |
High
waves with sea beginning to roll, dense streaks of foam with spray blown higher into
air--may cut visibility |
10 |
55 - 63 |
48 - 55 |
Storm |
Trees
uprooted; considerable structural damage occurs |
Very
high waves with overhanging crests, sea is white with foam, heavy rolling and reduced
visibility |
11 |
64 - 72 |
56 - 63 |
Violent
storm |
Widespread
structural damage |
Waves
exceptionally high, sea covered with foam, visibility further reduced |
12 |
73 - 82 |
64 - 71 |
Hurricane |
Maximum
wind damage |
Sea
completely covered with spray, air filled with foam, greatly reducing visibility |
13 |
83 - 92 |
72 - 80 |
|
|
|
14 |
93 - 103 |
81 - 89 |
|
|
|
15 |
104 - 114 |
90 - 99 |
|
|
|
16 |
115 - 125 |
100 - 108 |
|
|
|
17 |
> 125 |
> 108 |
|
|
|
Source: Meteorology, William L.
Donn, 1975, McGraw-Hill, Inc., New York.
| FUJITA SCALE FOR TORNADO INTENSITY |
scale |
category |
mph |
knots |
expected damage |
F - 0 |
WEAK |
40 - 72 |
35 - 62 |
light:
tree branches broken, sign boards damaged |
F - 1 |
|
73 - 112 |
63 - 97 |
moderate:
trees snapped, windows broken |
F - 2 |
STRONG |
113 - 157 |
98 - 136 |
considerable:
large trees uprooted, weak structures destroyed |
F - 3 |
|
158 - 206 |
137 - 179 |
severe:
trees leveled, cars overturned, walls removed from buildings |
F - 4 |
VIOLENT |
207 - 260 |
180 - 226 |
devastating:
frame houses destroyed |
F - 5 |
|
261 - 318 |
227 - 276 |
incredible:
structures the size of autos moved over 100 meters, steel reinforced structures highly
damaged |
SPOTTER TRAINING WEB SITES:
Introduction
To Observation Weather Techniques
NOAA
Quest Series VORTEX
NOAA
Severe Storms Spotter Guide Online
NSSL
Educational Information
Severe
Weather Safety - NWSFO Norman, OK
Spotter
Guide - NWSFO Norman, OK
Cloud
Boutique - PSC Meteorology Program
Selected
Internet Resources For The Beginning Storm Chaser
Storm
Spotters Guide - Guide To Meteorology (UIUC)
Storm
Track's Storm Chase Guide
Weather
Glossary For Storm Spotters
Basic
Weather Skills via FSU
Meteorology
Online Guides
The
Forecast Factory
|
