There is an increasing chance of thunderstorms for Katherine on Friday.
Subscribe now for unlimited access.
$0/
(min cost $0)
or signup to continue reading
Increasing moisture resulting in increased cloud cover from Thursday or Friday should lead to a slight reduction in temperatures to close to average and an easing of the heatwave conditions, the Bureau of Meteorology says.
Katherine's record heatwave of maximum temperatures above 40 degrees has now entered its 14th day.
The bureau is forecasting the chance of rain and a lowering of temperatures to under 40 on Friday.
"The increasing moisture will also lead to an increased chance of showers and thunderstorms, particularly over the northwest of the Top End where there's a high chance of showers and storms this weekend," the bureau says.
The problem is the weather system stopping the arrival of the wet season refuses to go away.
Some storms have already partially relieved the long dry in some areas of the Top End, although not Katherine yet.
But the wet season is being held at bay by a positive Indian Ocean Dipole.
The Bureau of Meteorology has been saying for months now the dipole is the reason behind the delayed monsoon onset, now not likely to early January.
Generally this means there is less moisture than normal in the atmosphere to the northwest of Australia
While the dipole "weekly value" has dropped slightly, the bureau today said "the event remains strong".
Sustained changes in the difference between sea surface temperatures of the tropical western and eastern Indian Ocean cause the IOD or dipole.
The IOD is one of the key drivers of Australia's climate and can have a significant impact on agriculture.
The IOD has three phases: neutral, positive and negative.
Events usually start around May or June, peak between August and October and then rapidly decay when the monsoon arrives in the southern hemisphere around the end of spring.
But not this year.
Interestingly, in the years the dipole has been monitored by the bureau, it was in a negative phase in 1998 when ex Cyclone Les brought record rain and devastation to Katherine.
A strong positive IOD remains and is forecast to maintain strong positive index values until the end of 2019.
IOD events break down once the monsoon trough transitions into the southern hemisphere, which typically occurs in early December.
More reading:
However, the monsoon trough is likely to be delayed this year, possibly due to the strength of the current positive IOD event.
As a result, the prolonged and widespread dry signal over much of Australia during 2019 (related to this event) is likely to persist into December, before weakening later in summer.
The bureau will provide its next wet season outlook this Thursday.
While you're with us, you can now receive updates straight to your inbox each Friday at 6am from the Katherine Times. To make sure you're up to date with all the news, sign up here.