QLD, NT, WA: Thunderstorms, troughs and a tropical low bring floods, heavy rain, and some incredible totals to N Australia
Wed 29 Jan 2020
| Much of the northern half of QLD had 100 to 200mm rain in the week to 09:00 Wednesday 29 January, but many pockets of 300 to over 500mm have caused flash flooding and some wide areas of inundation. BoM
Monsoon-like conditions have brought heavy rain across large parts of northern Australia in the past 10 days or so, with thunderstorms, trough lines and a nearly stationary tropical low all making maximum use of plentiful moisture feeding in from the NW and N of Australia.
In the week to 09:00 Monday 27th the highest totals were in an area around Darwin, where Gunn Point recorded 299.6mm and Howard Springs 295.0, but a broad swath of Northern Australia from the North Kimberley, across the NT Top End to central and northern QLD recorded 50 to 150mm with some much higher isolated falls.
On Tuesday and early Wednesday 28th/29th, however, there were some phenomenal rainfall totals on the QLD Central and Tropical North Coasts. Stations around Ayr, ESE of Townsville, recorded around half a metre of rain in the 24 hour to 09:00 29th.
Rita Island, at the Burdekin River mouth just ESE of Ayr topscored with 529mm as a convergence line moved over the area and just sat there for nearly 9 hours. Their rainfall for the hour to 03:00 on the 28th was 26mm followed by successive hourly readings of 38, 49, 57, 72, 70, 64, 44 and 42 to 11:00 28th after which the rain stopped.
Ayr itself recorded 421mm while nearby Ayr DPI's seemingly modest 24-hour total of 327.8 was an all-time record in its 70-year history. Some other sites with shorter histories also set all-time records. Here are the top falls and their distribution:
These satellite animations from Andrew Miskelly - first with standard visible light imagery followed by water vapour imagery showing moisture - dramatically show the main cause of the rain: abundant moisture being pulled in from the north around a low that was in far NW QLD at the time.
The low, a trough down through W QLD, the moisture and instability combined to produce torrential thunderstom falls in NW and W QLD, with many places picking up over 100mm in one hit. Both Normanton and Winton set new all-time records for one-day rain to 09:00 28th at their airport sites with 154.4 and 117.4mm respectively. A grazier from Winton Downs, 60km S of Winton, who was interviewed on the Country Hour had had two such dumps on consecutive days - 205mm on the 27th and 126 on the 28th. Winton Downs isn't a BoM official or flood station so timing and standards are unknown, but the time of the broadcast at noon suggested readings were taken around 09:00 ± a few hours.
Flooding is bringing back raw memories of the disastrous floods in February/March 2019, with several rivers that drain into Lake Eyre and the Gulf already at moderate flood level in places. However as the weekly rain map above shows, broadscale rainfall hasn't been anywhere near the same amount. This ABC article gives extensive and detailed coverage of the impact of the rain and floods in N and NW QLD, while Mount Isa's North West Star* gave practical information for NW QLD, like a long list of roads closed or affected by flooding or rain. The BoM's Weekly Rainfall Update gives a detailed analysis of the rain, its causes and its impact on drought conditions.
For heart-stopping moments, though, you can't beat the view the crew on this goods train from Townsville would have had as they approached this small bridge at Prairie, just east of Hughenden - and only just stopped in time.
For information on annotations (*, †, ‡, etc), translation using your browser, abbreviations and how AWN attributes sources go here.