Transition into monsoon season

RAIN WET: Monsoon conditions are later than normal but just around the corner.
RAIN WET: Monsoon conditions are later than normal but just around the corner.

The next couple of days and much of next week will be hot with not much rain for non-coastal locations across the NT, a bit like conditions in the early build-up.

The Bureau of Meteorology said tomorrow and on Saturday, the Top End may see some relief with a slight to medium chance of showers and storms in the western Top End, with just a very slight chance elsewhere.

Temperatures are forecast to be in the 40s for the next week in central areas of the NT with high 30s in the southern districts.

“Normally at this time of year there would be signs of the monsoon forming in the southern hemisphere – currently the monsoon focus remains north of the equator so we do not expect the monsoon to be active for north Australia during the next two weeks,” a bureau spokeswoman said.

“When the MJO (Madden-Julian Oscillation) is active in our part of the world, we see a pick-up in the weather and sometimes it is associated with an active monsoon phase – MJO is not likely to be in our area until towards the end of the month or early in January.

“The monsoon season, usually starting mid-late December and finishing early April, is characterised by two phases: the active monsoon and the monsoon break.

“Active monsoon is when we see widespread heavy rainfall and grey skies which can last from a few days to more than a week across the Top End - the monsoon trough is lying near or over the northern coast of Australia.

“Monsoon break is when the monsoon trough moves to the north of Australia and we see a return to more isolated showers and storms.

“Throughout the monsoon season, we are on the lookout for the development of tropical lows along and around the monsoon trough, which are often associated with heavy rainfall.

“All tropical cyclones start life as a tropical low – there is always a chance that a low will develop into a tropical cyclone if the atmospheric conditions are right and it stays over water for long enough,” the spokeswoman said.

MJO is the main climate driver affecting tropical rainfall patterns during the monsoon months, whereas an active La Niña will tend to enhance rainfall early in  the build-up months rather than during the monsoon.

“We are now in an active La Niña, but because it has formed so late in the year, it is weak and not expected to be active for long, its impact on rainfall for the tropics will be minimal,” she said.

The overall outlook for this wet season is for around average rainfall across the Territory: total annual rainfall average for Darwin is 1723mm, with 1090mm for Katherine, 476mm for Tennant Creek and 283mm for Alice Springs

“Monthly rainfall totals can be quite variable during the wet season, for example in Darwin the average December rainfall is 254mm, with the highest recorded at 665mm in 1974 and the lowest just 19mm in 1991,” the spokeswoman said.