Forecasters trawled through their knowledge gained from in-depth studies of past cyclone events to beat the computer to the punch. Tessi came ashore on the night of April 1 and saturated Castle Peak, causing landslides and considerable damage to expensive homes at the mountain's foot. One week later, computer models were again confounded when Vaughan, spinning towards Cairns, first intensified then mysteriously evaporated, leaving only the surface-level eye to spin harmlessly onto the coast. Callaghan says Tessie and Vaughan were classified as midgets, meaning they were created in the easterly trade winds without the help of moist and energetic monsoonal westerlies. These westerly winds are the lifeblood of northern Australia's wet season, and had failed to appear during the month of March.
Midgets develop quickly and degenerate quickly too.
As Callaghan says, there's no big spinning system to keep the storm going once inflow of moist tropical air vanishes. Ada, which clobbered Queensland's Whitsunday islands in the 1970s and Tracy which devastated Darwin on Christmas day 1974 were both classified as midgets. Because they are small and localised, midgets fly under the radar of computer modeling systems. Silicon-chip forecasting tends to look at the bigger picture. Often the data for small events has yet to be entered into the program.