A STORM has to meet at least one of a few criteria to meet the definition of a severe storm in the eyes of the Bureau of Meteorology.
If a storm brings hail of 2cm of more, winds of more than 48knots or 90km/h, or high rainfall, the BoM considers it a severe storm.
The definition of "high rainfall" varies from place to place but on the Sunshine Coast, is generally around the 50-60mm per half hour mark.
At Coolum and Tewantin, 54mm in 30 minutes of 74mm in an hour is considered high, while at Caboolture, the mark is a little lower at 51.5mm in 30 minutes or 689.4mm per hour.
In comparison, 40mm in 30 minutes or 51mm in 60 minutes is considered high rainfall at Oakey, on the Darling Downs, and 54mm in 30 minutes or 77mm in an hour is classed as high at Tully, in North Queensland.
BoM forecaster Vinord Anand said the Bureau could often forecast the possibility of severe storms days ahead based on conditions.
However, there is a difference between a forecast and a warning.
Warnings are issued only for severe thunderstorms, and the Bureau cannot issue a warning that a severe thunderstorm is on the way until at least one of the criteria - the hail, rain or wind - is occurring in "real time".
"We can see the conditions a few days out to see if they meet the conditions (for a storm) but for the warnings, we have to see them happen," Mr Andand said.
"Once we start to see the criteria, that's when we can do the warnings," he said.
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