Welcome to our third of many wet season wrap ups for Northern Australia where we take a look at Northern Australian towns/cities and go through their previous wet season. In October, we continue our features by speculating at what the early modelling might be showing for their upcoming wet season so become a subscriber, show your support and get access to this exclusive information. Today we go into North-West Queensland and specifically the towns of Mt Isa (pop 22000).
Mount Isa is of course known for its mining operations, but that area is also home to vast cattle grazing properties. The region is fed by the Julius Dam and Lake Moondarra. The 2018/2019 wet season was basically one week of rainfall. The monumental system that hit Townsville in late Jan/early February created a secondary circulation in North-West Queensland to the near Noprth-East of the Isa with a trough linking the two areas of interest. Without that system resulting in that week of record breaking rainfall, this would have been a very poor wet season for this entire region.
WET SEASON 2018/19 RAINFALL A strong storm on the 13th November dumped over 30mm on the city and packed wind gusts near 90km/hr but that was about the peak of the storm activity for the build up period. There were a few gusty storms in the district in October and November but they provided very little rainfall on the city. The generally inconsistent build up was followed by the driest December ever recorded in Mt Isa. barely a drop registered in a month where storms should be a dime and a dozen.
January was much the same with very little rainfall during the month. Late in the month we began seeing a destabilization of the atmosphere and a complex synoptic pattern was establishing itself over the area. Early in February while the Townsville coast was encountering an incredible weather event, a new offshoot of that system was forming in the North-West. The rain began in the Isa on Thursday the 31st January and then continued until the 5th February. Luckily for the city it was located just to the west of the developing LOW pressure system, that meant the heaviest rainfall remained well east of the Isa (more on Cloncurry in another update). Nevertheless, the system created 123mm of rain in a 24 hour period between 9AM Friday (1st Feb) and 9AM Saturday (2nd Feb). In fact in that 5 day period, about 70% of the entire season's rainfall fell. The unusual slow moving nature of the rain depression and associated trough meant that even though the heaviest rainfall was not over the city itself, the Isa still managed to break its 50 year February rainfall record.
Following on from that crazy 5 day period of weather, the Isa saw just one more significant storm for the rest of the season on the 23rd February dumping a further 33mm. That was it for a season of stark contrasts - the driest December ever recorded followed by the wettest February ever recorded. If there was ever a place that shows the variability of wet season rainfall it was the Isa.
TROPICAL CYCLONE IMPACTS
No Tropical Cyclones or remnants from Tropical Cyclones affected Mt Isa in season 2018/19. A complex rain depression did form to the near North-East of the city on January 31 and operated in the region until February 4th. The system dumped upwards of 500mm in pockets of the north-west and strong winds were experienced to the south of the LOW.
The start of the wet season was one of the hottest periods ever experienced in the Isa with both December and January breaking 50 year maximum temperature records. The average maximum temperature for both of those months was over 40 degrees celsius. Thankfully those hot temps were moderated somewhat by the drier airmass around the region. A daily temperature record was also broken on December 21 with a steaming hot 45.3 degrees recorded and not a storm in sight to provide relief that day.
In stark contrast, with that LOW to the North-East of the city, a strong southerly airmass and overcast, rainy conditions dropped the maximum temperature about 10 degrees below average for about 7 days in a row between February 1 and February 7.
Once again we saw the massive variability of Mt Isa's wet season weather in those temperature extremes.
Where do we go next? Tune in tomorrow night to find out.
A reminder that we provide an in-depth weather subscription service for detailed significant weather information across the north of Australia. Head to https://join.ozcyclonechasers.com.au to show your support and join us