glossary
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ACCAS - Altocumulus castellanus - a cloud you want to see before storm development. It shows the instability in the middle of the atmosphere. When moist low level cumulus occurs at the same time, storms can nearly (80%+ chance) be expected somewhere in the area.
Anvil - The high, mostly flat top of a thunderstorm. If the anvil edge is sharp, this usually means the storm is strong. If it is weak and fibrous looking, the storm is usually weak.
Backshear - In a strong thunderstorm, the anvil or higher updrafts often push against the upper winds due to the updraft strengths - this is called a backshear.
Cb - Cumulonimbus - a storm cloud.
CC: Cloud to cloud lightning | CG: Cloud to ground lightning | CA: Cloud to air lightning
CJ - Slang for Cumulus congestus - often leads to towering cumulus and cumuloniumbus clouds.
Cold Pool - The first swim in Summer… it's always freezing! Just kidding… this term usually means upper air is colder than normal, often resulting in unstable weather conditions.
Cu - Cumulus cloud - a low level 'fluffy' cloud.
Downburst - See microburst.
EF-0, 1, 2, 3, 4, 5 - Tornado intensities. The higher the number, the more intense and damaging it is.
Flang - (Slang) When the flash of the lightning strike and bang of the thunder happen almost simultaneously!
Gale - Winds of at least 63km/h.
GFS - Global Forecasting System - one of the better forecast models around.
Golfballs - Often these are used to describe the size of hail that fell - tennis ball, cricket ball, softball also used.
Gust Front - Often cooler and fresh winds come out of a thunderstorm, accompanied by a line of cloud, sometimes called a shelf cloud.
Hail - Balls of ice that falls from a shower or thunderstorm. In Australia, the term 'large hail' applies to hail more than 2cm in diamater, or the size of a $2 coin or bigger.
IC - lightning Inter-cloud lightning - lightning that occurs inside the cloud however visible 'bolts' can't be seen.
Inflow - Winds flowing into a thunderstorm. As a rule, the more severe the thunderstorm is, the stronger inflow it has. These winds can be damaging.
Knots (kn) - Wind speeds are often measured in knots. 1kn = 1.854km. 100kn = 185.4km/h.
Left moving - At times of high instability, a storm will initially move with the general steering winds. When it intensifies, it will often move more to the left of the steering winds. In some situations, a storm will split, leaving one left moving storm and one right moving storm!
Marburg Radar - In the last few years, this has become the 'old' radar, with Stapylton Radar becoming the main one. It is still very useful though, as the Marburg radar sees areas further west. Both radars are very different, and a judgement on storm intensity can be made by comparing the two.
Mesocyclone - A vortex of air, approximately 2 to 10 km in diameter, within a thunderstorm.
Microburst - Severe winds that occur under a thunderstorm caused by the weight of the rain/hail falling. These winds can reach more than 250km/h.
Multi-cell - A thunderstorm made up of two or more single-cell storms.
Outflow - Winds blowing away from a thunderstorm
Propagation - Often storms will continually develop on the same side of a storm, making it look like the storm is moving that direction, when really, it is propagating in that direction. This often occurs when low and mid level winds are weak.
Rainfoot - When rain falls out of a thunderstorm, it often is blown a little ahead of the storm near ground level, giving the appearance of a 'foot'.
RFB - Rain free base - the base of a storm cloud that often is a sign that rain/hail/lightning is about occur under this cloud and sometimes these appear before a wall cloud forms under it.
SEQ / SE Qld - South-eastern Queensland, Australia... where I am!
Shear - The strength of winds at different heights of the atmosphere.
Sheet lightning - See inter-cloud lightning.
Shelf Cloud - See gust front.
Single-cell - A storm consisting of a single 'cell'. These usually die off within 20-30mins unless joined by other cells.
Squall line - A line of storms joined together. Sometimes there could be more than a dozen storm cells in this line, and stretch over 1000km.
STA - Severe Thunderstorm Advice - these have now been superceded by STW.
Stapylton Radar - The main rain in SEQld, located at Mt Stapylton, SE of Loganholme (the big golfball you see east of the M1 between Brisbane and the Gold Coast)
STW - Severe Thunderstorm Warning.
Supercell - A severe thunderstorm with a sustained rotating updraft.
TC - Tropical Cyclone.
Triple Point - This is an area where winds from three different directions converge in the same spot. This often helps storms in SE Qld fire up, when we have NW winds converging with NE and into a SE change. A storm tracking into this area may start rotating as a supercell.
TCu - Towering cumulus - these clouds sometimes become cumulonimbus (Cb) clouds.
Updraft - The cumulus towers that often are part of, or lead to thunderstorms.
VDS - Very Dangerous Thunderstorm - the Bureau of Meteorology note a VDS on a STW when a thunderstorm appears particularly severe.
Wall cloud - The lower cloud area that rotates, and forms under the base of a (usually) severe thunderstorm.
wx - Short for weather
YBBN - The METAR code for Brisbane Airport.
