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Dayton
SKYWARN Spotter's
Reference Material
To Be Used During
Severe Weather
Spotting |
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What
to Report to
Dayton SKYWARN
During Severe
Weather |
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The
National Weather
Service (NWS) has
the responsibility
of organizing and
instructing Amateurs
to participate in
their Skywarn
program. Dayton
Skywarn will assist
NWS during the
Amateur portion of
the class, within
the Dayton Skywarn's
counties of
responsibilities.
(Wilmington NWS
Website is
www.nws.noaa.gov/lin/lin) |
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Estimating
Hail Size |
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Pea
Size = 1/4" |
Quarter
Size = 1" |
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Marble
Size = 1/2" |
Golf
Ball Size =
1 3/4" |
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Nickle Size = 3/4" |
Baseball
Size = 2 3/4" |
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Spotters
Rules and Clues |
Estimating
Wind Speed |
| 1.
Always have a safe
place nearby to
protect yourself
from wind or hail. |
Calm
Smoke rises
vertically. |
| 2.
Cars are safe places
in case of lightning,
but not in the case
of tornadoes. |
1
- 3 MPH
Direction of wind
shown by smoke drift
but not by wind
vane. |
| 3.
Moving Water is very
powerful, it only
takes a slight
current to push our
car off the road. Do
not drive a vehicle
through roads
covered by moving
water. |
4
- 7 MPH
Ordinary wind vain
moved by wind. |
| 4.
Large hail often
falls just in
advance of a
tornado, especially
large tornadoes. |
8
- 12 MPH
Leaves and small
twigs in motion,
light flags
extended. |
| 5.
Tornadoes
generally moves
toward the
north-east at 25 to
35 MPH when
associated with
fronts and squall
lines. |
13
- 18 MPH
Dust raised, loose
paper raised, small
branches move. |
| 6.
Ground
speeds of a tornado
can exceed 70 MPH.
Go to a substantial
building instead of
trying to out run an
approaching tornado. |
19
- 24 MPH
Small leafy trees
sway, crested
wavelets form on
lakes and ponds. |
|
25
- 31 MPH
Large branches in
motion, whistling in
telephone wires or
link fences. |
| 7.
The first gust of
wind to reach you
from a thunderstorm
is frequently the
strongest. |
|
32
- 38 MPH
Whole trees in
motion,
inconvenience in
walking against
wind. |
| 8.
A rain-free base
denotes the storms
up-draft area. A
place to watch
closely. |
|
39
- 46 MPH
Twigs and small
branches break off
trees, impedes
progress walking. |
| 9.
Wall clouds form
from the rain-free
base often 15 to 20
minutes before a
tornado occurs. |
|
47
- 54 MPH
Slight structural
damage, chimneys
have bricks loosened
and shingles blown
off roof. |
| 10.
Watch Wall clouds
closely for 1 to 2
minutes to determine
if there is any
rotation. |
|
55
- 63 MPH
Trees up-rooted,
widespread
structural damage,
mainly roofs |
| 11.
Look carefully,
Spotters may not be
able to see a
tornado due to it
being wrapped in a
curtain of rain. |
|
64 - 72 MPH
Damage to structures
major and
widespread. Roofs
and window damage. |
| 12.
Over-shooting
tops are an
indicator of very
strong storms. |
|
73 - 112 MPH
Peels surface off of
roofs, windows
broken, moving autos
pushed off of road,
some mobile homes
overturned. |