Northern parts of Australia have been under a flood warning this weekend, with further flooding set to bring havoc to south-eastern parts of the Northern Territory and western Queensland early this week. A broad trough – an area of locally lower pressure – has been moving across northern Australia, dragging in warm, moist air from the Gulf of Carpentaria and providing the perfect ingredients for the formation of severe thunderstorms, and even supercells.
More than 70mm (2.75in) of rain fell in an hour under the slow-moving storms over the weekend in what is usually an arid, low rainfall zone with a desert/grassland climate classification. Some parts of the region have sparse observation data, but some local stations have been able to record more than 100mm within 24 hours, with 132mm of rain at Marion Downs, Queensland.
The high rainfall to such dry ground heightens the risk of flash flooding, with flooding also often occurring after the weather events have passed as river catchments merge. While minor flood watches are in place, a more moderate flood watch is likely to be issued later in the week as water transports through various river catchments, with the potential for communities and transport links to be cut off. As the trough moves further east into Queensland through Monday and Tuesday, some models are predicting that central/southern parts of Queensland will receive 200mm of rain within a 24-hour period, with perhaps another 100mm or so into Wednesday, exacerbating the flash flood risk for the remainder of the week.
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In China, many areas will experience a stark contrast in temperatures over the coming days, with drops in temperature greater than 20C in less than 48 hours. Daily maximum air temperatures will continue to reach the low to mid 30s celsius across large swathes of southern and eastern China this week, up to 18C above the average for the time of year. A maximum temperature of about 35/36C is forecast in Shanghai on Wednesday, while the daytime maxima may struggle to reach the teens celsius by Friday. Yet the most impressive temperature change could be in Lanzhou in the northern Gansu province, with a daily high on Tuesday of 25C plummeting to just above 0C by Thursday. The climate average for this time of year is normally about 16C. While swings in temperature in the spring months are not unusual, the scale and speed of the change from unusually hot to cold conditions is impressive.