December 21, 2024
Much of 2024 has been quite dry for Townsville. In fact, in the eight months to November 30, the city had recorded only 203.6mm of rain. While low, this is actually not much lower than the long-term average of 246.5mm for the same period.
However, that all changed this month with a recent deluge delivering nearly 250mm to the city in the last 48 hours. Combined with earlier showers and storms, the December total now sits at 465.8mm, making it the wettest December in Townsville since 1907, when 641.5mm was recorded across nearby Townsville sites. It’s also a site record for Townsville Airport, as 465.8mm is the highest December total officially recorded there (this site wasn’t operating in 1907).
It wasn't just Townsville - areas of Mackay and Proserpine also recorded a deluge - our Virtual Rain Gauge Network picked up falls of more than 400mm near Proserpine.
Virtual Rain Gauge Network rainfall between Mackay and Proserpine. Source: MetCentre
Convergence Lines: The Rainfall Culprit
Convergence lines are notorious for delivering large amounts of rainfall in a short time, and this event was no exception. A southeasterly change swept rapidly through NSW and southern Queensland before stalling as it moved into northern Queensland. Here, humid southeasterly winds collided with northwesterlies associated with an active Madden-Julian Oscillation (MJO), creating ideal conditions for heavy rain.
ACCESS precipitable water along a convergence boundary near Townsville and a developing tropical low yesterday Source: MetCentre
Adding to the setup, a small tropical low has developed offshore. While there is a chance this system could evolve into a tropical cyclone, the likelihood remains low. Even if it does develop, current conditions suggest it would track eastward, away from Australia.
Looking Ahead
This means much of Australia is still on track for a relatively uneventful Christmas weather-wise. However, a strong cold front could bring elevated fire dangers from Boxing Day across South Australia, Victoria, NSW, and Tasmania. Our meteorologists will be closely monitoring this system in the days ahead.
ACCESS 850mb temperatures & wind barbs on Boxing Day showing high temperatures and strong winds ahead of a cold front. Source: MetCentre
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