Welcome to our eighth wet season wrap up 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 the upcoming wet season for these locations so become a subscriber, show your support and get access to this exclusive information. Today we head to North-East Queensland and specifically the town of Mareeba (pop approx 11100).
Farming is the life blood of this community. Crops like avocados, mangoes, lychees, coffee, macadamias and sugar cane tend to round out the most popular crops grown in the area. The region is supplied water through the Tinaroo Dam located to the South-East of the town and the region has a solid and sustainable 'user pays' irrigation system for its farmers. Mareeba itself lies in a rain shadow area protected from significant amount of rainfall by mountains to its east that block moist easterly winds from dumping their loads on the town. A rain gradient of about 1000mm (1metre) over just 10kms as the crow flies occurs to its east. When the region receives very deep tropical easterly winds, even those mountains aren't strong enough to stop the town from receiving good rains and the town also tends to benefit from storms that come from the higher ground of the Atherton Tablelands to its south early in the season. The town can come under the influence of the monsoon trough as well but those north-westerly winds associated with the trough have usually dumped their initial loads well to the town's north-west and whatever is left of them simply causes an increase chance of showers and storms in the region. Showers and storms that affect the town are usually slow moving due to weak upper level winds and can cause very heavy rainfalls over a short space of time. While hail can occur with drier storms over the town every few years, this is a far more regular occurrence in higher country to its south.
WET SEASON 2018/19 RAINFALL Overall the wet season was actually pretty typical. It rained when it was supposed to rain (December to March) and it was relatively dry when it was supposed to be relatively dry (Oct/Nov/Apr). If there was to be a criticism of the 2018/19 season it would be the lack of early season storm activity north of the Atherton Tablelands. The town saw a good thunder bumper on the 13th October and then it took over a month until they got another one, in what can best be described as a non-existent build up. It is rare to see such a poor period of storm activity across this region of the world.
Come the start of December, I don't think many would have held high hopes for a decent wet season, but the weather Gods had other ideas. In a complete reversal from what happened in yesterday's update for Emerald, Mareeba's wet season went KABOOOMM. 85km/hr winds plummeted the temperature mid afternoon on the 3rd December from 35 degrees to just 23 degrees in 10 minutes and dumped a quickfire 20mm of rain. Read the Cairns Post story here. Showers, storms and cloudy conditions then dominated the weather pattern as my good old mate Owen (TC Owen) began tracking west out there in the Coral Sea. The 9th December was a particularly noteworthy period of rainfall with 81mm falling on the town up until 9AM on the 10th. That fall was in response to Ex Owen hitting the coast around Cairns and tracking west across the Peninsula, only to reform a couple of days later in the Gulf. With Owen meandering around like a drunken sailor in the Gulf and Penny (TC Penny) then developing at the back end of the month, a deep moist easterly flow was able to overcome the mountainous obstacles of the Great Dividing Range and penetrate inland to give Mareeba numerous good dumpings at the back half of the month.
With Penny moving East across the Northern Peninusla and into the Coral Sea in early January, the region got a brief reprieve from heavy rainfall and in turn copped some warm days. However the monsoon had settled down following Penny and we went through a lull in activity for most of the month until a new LOW popped up along the Western Peninsula in late January with that LOW tracking southwards through the Peninsula on the 25th and 26th January it brought down a significantly strong convergent flow of moisture which affected Mareeba dumping about 150mm of rain on the town between Jan 25-Jan 27. As that system traveled southwards it stalled with strong convergence zones forming well south of Mareeba late in the month which eventually led to the monumental Townsville floods of early Feb.
Mareeba found itself on the northern fringe of the monumental North Queensland flood event in early February. This meant the town was under the influence of a deep moist monsoonal type northerly flow so daily bouts of mid to late afternoon heavy showers and storms were the order of the day for about 10 days in a row from late Jan to Feb 7. It was actually quite a lucky break for this region that the flood event had set itself up south of the Tinaroo catchment zone because by the end of January that catchment was almost saturated and the dam was nearing 100% capacity. Had the flood event set up over the catchment zone, we would have likely seen some disastrous consequences over a much larger region. After the first week of February the atmosphere allowed everyone to catch their breath with very little weather activity in the region for the remainder of the month.
March was back to the usual for my old hometown because many locations on the North Tropical Coast and Tablelands region did quite well for rainfall, but that rain shadow effect eventually caught up with the town. Mareeba recorded a disappointing 100mm of rain in March despite some very heavy falls on the coast and in other inland parts to their south. The 20th March was a great example of how much of a grip the rain shadow effect has on the town. Look at the 24hr radar pattern here and have a guess how much rain the town got? (Answer at the bottom of the page - Cairns copped over 100mm that day). April was also poor as south-easterly winds and shallow levels of moisture meant that the town had no chance of seeing any decent late season rainfall.
All up it was a typical wet season with the highlight being late Jan/Early Feb.
TROPICAL CYCLONE IMPACTS
Ex Tropical Cyclone Owen hit the Cairns coastline on December 10 (see the radar loop above), but the LOW at that stage did not pack any significant winds, so the area just saw an increase in shower activity. Another LOW at the end of January which became the catalyst for the North Queensland flood event tracked south across the Western Peninsula on the 24th and 25th January. It too was not packing any significant winds but resulted in a widespread rain and storm event at the end of January.
Temperatures across the town were unremarkable right through the wet season with the exception of the final few days of November and the first few days of December right before the big KABOOM of the wet season. 10 of the previous 11 days before the big Kaboom saw maximum temperatures soar to 5 degrees or more above average. In fact the town's daily maximum temperature record was broken an astonishing 5 times in 6 days between November 25-November 30 with the new record now standing at 39.8 degrees on the 26th November 2018.
The LOW pressure system that kicked the NQ floods off late in January also provided Mareeba with a record daily low Maximum temperature under the cloud and rain on January 25th with the max climbing to just 23.2 degrees.
Where do we go next? Tune in Monday night to find out. By the way answer to the Mareeba rain question on March 20 that I asked above, was 28mm
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