Ten deadly weather signs

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• Ten deadly weather signs
• Martin Babakhan
• Meteorologist

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Proactive Decision-Support for Severe Weather
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What products do I use in what situation?
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BE WEATHER-WISE

• Understanding and recognising the following
  weather clues will assist flight safety!

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• Towering Cumulus cloud.
• Cumulonimbus.
• Microburst.
• Mammatus cloud.
• Lens shaped cloud.

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• Funnel shaped cloud.
• Virga.
• Anvil cloud.
• Castellatus cloud.
• Super cells.

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1 TOWERING CUMULUS 2CUMULONIMBUS
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TOWERING CUMULUS
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FLANKING LINE OF STORMS - GLADSTONE
QLD.
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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).

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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.

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3DOWNBURST MICROBURST
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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.

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• 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!

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RAIN CURTAIN MICROBURST
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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.

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VERY HEAVY RAIN CURTAIN LIGHTNING
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4MAMMATUS CLOUD
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• 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.

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MAMMATUS
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5LENS SHAPED CLOUD
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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.

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6FUNNEL SHAPEDCLOUD
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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.

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• TYPICAL
• FUNNEL
• SHAPE
• OF TORNADO.
• NORTHAM W.A

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• 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.

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WATERSPOUTS
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• A landspout is formed when relatively cool air
  passes over hot ground.
• In the next slide, note the lack of anvil and the
  absence of any wall cloud associated with the
  large cumulus cloud.

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LANDSPOUT - CLEVE S.A
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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.

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WALL CLOUD BENEATH RAIN FREE STORM
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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.

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WALL CLOUD - ADELAIDEROTATING CLOUD BASE
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7VIRGA
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• Virga, or rain which evaporates before reaching
  the ground, often looks like dark, tapered
  extensions below a cloud.
• It is diffuse and soft-edged.
• Be aware of possible downdraughts.

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VIRGA
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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
  short-lived.
• If the top appears dome-like and lasts for a
  fairly long period of time, the supercell is more
  than likely severe

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8ANVILCLOUD
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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 !

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THUNDERSTORM - ANVIL
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THE ANVIL

• The 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.

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FIBROUS ANVIL
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• 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.

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OVERSHOOTING ANVIL BACK-SHEARED
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SEVERE STORM ANVILWITH NOTCHES
OVERSHOOTING TOP.
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9CASTELLATUSCLOUD
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• Altocumulus castellatus- an indicator of
  instability.
• Note the separate towers.

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ALTOCUMULUS CASTELLATUS
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10SUPERCELLS
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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

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SUPERCELL STORMFISKVILLE VIC.
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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 back-sheared anvil.

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ISOLATED SEVERE STORM POINT LOOKOUT N.S.W
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11SUPERCELLS
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FINALLYREMEMBER TO CHECK FOR SEVERE
WEATHERWARNINGS.
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The End