A prolonged period of low wind will impact the National Electricity Market (NEM) this week, which is coinciding with bitterly cold weather driving up energy demand in the southeast. 

The weather systems appear to be stuck, with record challenging high-pressure expected to sit over Tas for an extended period.  

The images below show this stubborn high-pressure system sitting over Tas or the Bight for at least 6 to 7 days.  

Images: Mean Sea Level Pressure (MSLP) on Monday, July 1 (top), Wednesday, July 3 (middle) and Saturday, July 6 (bottom).  

This high-pressure system should prevent fronts or fierce winds from crossing southern Australia this week, bringing a prolonged period of light wind for the NEM.  

The impact of the high pressure is already being felt in the market, with wind power only contributing 656MW or 2.2% to generation at 10:30am Monday, July 1.  

Image: Wind power contribution to generation for 7 days leading up to Monday, July 1. Source: OpenNEM 

You can see in the image above that this lull in wind power comes after a windy week, which was caused by several cold fronts crossing the region. 

The light winds are set to continue for most of the week for the NEM, especially in the wind generation areas in Vic and Tas, which are closest to the central high pressure.  

Unfortunately, this will coincide with extremely cold nighttime temperatures across Vic and Tas, with Melbourne set to see a run of 5 to 6 mornings below 4°C from Tuesday night. 

Some good news is that for SA, Qld, NSW and the ACT wind generation areas, winds should pick up later in the week as a surge of easterly winds feeds into a cut off low in SA. 

Image: Instantaneous wind gusts at 1pm on Friday, July 5, according to ECMWF 

This is in response to a rare ‘northeast cloudband’ which should cause thick cloud to stretch from the Coral Sea down to SA later this week. The cloudband should reduce solar output across parts of QLD, NSW and SA and bring significant rain totals to these areas. 

Looking ahead, wind should remain light across Vic and Tas for at least the next 7 days. The models are suggesting that a strong cold front and decent wind could pass across southeastern Australia mid- next week.  

Weatherzone Business, a DTN company, supplies precise weather intelligence to over 75% of the National Energy Market (NEM) participants and is the trusted provider for Australia’s Market Operator. To find out more, please contact us at business@weatherzone.com.au.