Ten deadly
weather signs
Martin Babakhan
Meteorologist
Proactive Decision-Support for
Severe Weather
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What products do I use in
what situation?
BE
WEATHER-WISE
Understanding and
recognising the
following weather clues
will assist flight safety!
Towering
Cumulus
cloud.
Cumulonimbus.
Microburst.
Mammatus cloud.
Lens shaped cloud.
Funnel
shaped cloud.
Virga.
Anvil
cloud.
Castellatus cloud.
Super cells.
1
TOWERING
CUMULUS
2
CUMULONIMBUS
TOWERING CUMULUS
FLANKING LINE OF STORMS GLADSTONE QLD.
Cumulus Clues
Keep at least five nautical miles away from
developing Cumulus/ large Cumulus.
 Keep as far away as possible from
Cumulonimbus because of hazards eg: turbulence; wind shear and gust fronts
[which may exist quite some distance from
the edge of the cloud], and
 microbursts (a strong concentrated
downburst of cold air).

Clumulus clues
 Never
try to outclimb a towering CU
or developing CB. Their growth
may exceed you climb rate and you
may end up inside a storm cloud.
 Avoid flying under the clear area
below the anvil, because of the
dangers presented by hail falling
from the anvil.
3
DOWNBURST
&
MICROBURST
DOWNBURST
&
MICROBURST
Wind squalls may also be generated by
downbursts.
 Concentrated, severe downdraughts are
usually accompanied by a descending
deluge of precipitation.
 These induce an outward [horizontal]
burst of damaging wind at the surface
which on a smaller scale is known as a
microburst.

 Outwardly
curved rain shafts
are a good sign of strong
downburst or microburst
winds and the steeper the angle
the stronger the flow.
 In the next slide, the rain curtain
has a “foot” close to the ground.
 Also note the rising rain or dust
well to the right!
RAIN CURTAIN & MICROBURST
RAIN CURTAIN
Other clues of storm severity can be
found in the rain curtain: If it is dark & smooth [as previous & next
slide], very heavy rain is likely.
 Rainfall in severe storms will become
progressively heavier & sometimes mixed
with hail. Weaker storms have patchy
rainfall or short downpours.
 Severe storms have multiple lightning
bolts.

VERY HEAVY RAIN CURTAIN
& LIGHTNING
4
MAMMATUS
CLOUD
 Mammatus are rounded pouches
or bulges which indicate descending
pockets of small droplets or ice
crystals from an anvil surface.
 They
can also be seen below middle
level cloud.
 They
are associated with severe
turbulence.
MAMMATUS
5
LENS
SHAPED
CLOUD
LENS SHAPED
CLOUDS
When observed to the lee of a mountain
range they indicate mountain wave
activity and possible severe turbulence
[especially below the cloud].
 Strong wind flow over ranges gives rise to
downstream lee wave action.
 Mountain waves can also occur without
lens shaped clouds being present [in dry
air].

6
FUNNEL
SHAPED
CLOUD
TORNADO
 The
typical funnel shape of a
tornado is formed when moist air
condenses within the lower pressure
of the rotating column of air.
 Under relatively dry conditions, it
may not form and the only evidence
of a tornado at the surface may be
indicated by a mass of debris [eg
dust].
TYPICAL
FUNNEL
SHAPE
OF TORNADO.
NORTHAM W.A
A
waterspout
looks like a
tornado, but occurs over water when
cool unstable air passes over warmer
waters.
 Local topography etc allows local
convergence of the air flow, which
results in vigorous updraughts
“tightening up” into spinning
columns.
 They mostly occur in late Summer &
Autumn.
WATERSPOUTS
landspout is formed when
relatively cool air passes over
hot ground.
A
 In
the next slide, note the
lack of anvil and the absence
of any wall cloud associated
with the large cumulus cloud.
LANDSPOUT - CLEVE S.A
WALL CLOUD
A
small cloud feature, particularly
valuable is assessing a storms severe
potential, beneath a rain free cloud
base can be found toward the rear of
the storm.
 This localised cloud base lowering
occurs at the site of the main,
focused updraught into the system.
WALL CLOUD
BENEATH RAIN FREE STORM
WALL CLOUD
As a storm becomes stronger and
develops an organised inflow, its main
updraught may begin to rotate slightly.
 This can be seen as broad rotation of the
cloud base beneath the main updraught
or in the circular nature of the wall
cloud.
 In the Southern hemisphere viewed from
a distance the rotation will be clockwise.

WALL CLOUD - ADELAIDE
[ROTATING CLOUD BASE]
7
VIRGA
 Virga,
or rain which evaporates
before reaching the ground,
often looks like dark, tapered
extensions below a cloud.
 It
 Be
is diffuse and soft-edged.
aware of possible
downdraughts.
VIRGA
Supercell Visual Clues
Visual characteristics can be used to determine supercells




Anvils can indicate where the storm is moving and
possible the strength of the updraft
The direction of cirrues is being blown off is the general
direction of movement
If the top is small, chance are the storm will be shortlived.
If the top appears dome-like and lasts for a fairly long
period of time, the supercell is more than likely severe
8
ANVIL
CLOUD
AN ANVIL
Is the top of a thunderstorm cloud;
 It can reach up to a height of 10-16
kilometres [approx 32 - 52,000 ft];
 May appear to be “boiling” ,but more
often has a fibrous, frozen appearance;
 It is primarily composed of ice crystals;

 The
next slide shows a crisp
thunderstorm anvil which is a good
indicator of a strong updraught !
THUNDERSTORM - ANVIL
 The
THE ANVIL
anvil can indicate the age,
strength & organisation of the
thunderstorm.
 Unevenness on the top indicates
erratic growth, while
 A diffuse edge suggests weak
updraughts [a weaker system].
 The
next slide is an example of a
weak, fibrous anvil from a non
severe storm.
FIBROUS ANVIL
 The
top of the anvil is normally
restricted by the tropopause and
blown forward on strong winds
aloft .
 When the main updraught is
very strong a portion of the anvil
may push upward above the
general level into the
stratosphere. This feature is
known as an overshooting top.
OVERSHOOTING ANVIL
& BACK-SHEARED
SEVERE STORM ANVIL
WITH “NOTCHES” &
OVERSHOOTING TOP.
9
CASTELLATUS
CLOUD
Altocumulus
castellatus:- an indicator
of instability.
[Note the separate
towers.]
ALTOCUMULUS CASTELLATUS
10
SUPER
CELLS
A SUPERCELL
Maintains an intense steady state
for many hours.
Is a dangerous cloud complex
and accounts for most of the
serious thunderstorm events.
NOTE the high, crisp anvil in
the next slide, which indicates a
very strong , sustained updraught
SUPERCELL STORM
FISKVILLE VIC.
Characteristics of severe
storms
 An
overshooting top that is prominent
and lasts for longer than several
minutes.
 a high anvil with a crisp edge;
 a steep, almost vertical mass of boiling
towers at the rear of the storm;
 a tendency for the anvil to push back
against the prevailing winds [a backsheared anvil].
ISOLATED SEVERE STORM
POINT LOOKOUT N.S.W
11
SUPER
CELLS
FINALLY
REMEMBER TO CHECK FOR
SEVERE
WEATHERWARNINGS.
The End