Darwin's famous dry season has been disturbed by an out-of-season drenching with the airport recording 52.4mm - the wettest September day since 1981, or 43 years ago!
While September’s average rainfall is a mere 16.3mm, this event stood out not for its intensity - but for its unusual timing. During the wet season, falls of 50-60mm in a day are common. For instance, Darwin typically sees more than 400mm of rain in January, the heart of the wet season.
The September average rainfall is just 16.3mm - a far cry from the average of more than 400mm normally recorded in January. For this reason, the event is certainly by no means extreme - just an unusual time of year to occur.
What Caused This Out-of-Season Rain?
The heavy rain was driven by a large upper trough across central to northwestern Australia, creating unusually strong northerly winds in the upper atmosphere. These winds dragged moisture from Indonesia southwards over the Top End, fueling the unexpected rainfall.
GFS 500mb temperatures showing the cold air in the upper atmosphere arching into northwestern Western Australia. GFS 300mb winds also show the strong northerly flow dragging moisture down from Indonesia. Source: Weatherwatch MetCentre.
Rainfall Across the Region
Darwin wasn’t the only location to experience significant rain. Howley Creek recorded 80mm, but even heavier falls were captured by our Virtual Rain Gauge Network. In areas where no physical rain gauges were present, our network detected pockets of 100mm, showing the localized intensity of the event.
Rainfall map courtesy of the Virtual Rain Gauge Network. Source: Weatherwatch MetCentre.
Weatherwatch - your trusted partner in Weather Intelligence.
Comments