MEDIUM TERM - HOW LONG DOES THE STAGNANT PRESSURE PATTERN LAST FOR ACROSS THE NATION?

The slack pressure pattern in line with the La Nina phase that is in place is expected to continue this week, meaning those most of us will see more of the same weather. That means this week, the east, far north, and west is wet and everywhere else is relatively dry. Most areas should see above average temperatures away from the east coast until mid week and then we see temperatures dive over the southeast and eastern inland with the southerly flow freshening later this week into the weekend.


Now into the medium term, the weather is expected to remain fairly stable for large parts of the nation, a good signal that the pattern is shifting to the cooler season, with periods of stable and mild sunny Autumn weather with light winds developing for large areas of the nation. We also see a reduction in the influence of the moisture over northern Australia and the showers and storms turning more isolated over the NT but more remaining more widespread about FNQ.


Along the east coast, this is wet season, so in between large scale rainfall events, showers continue at times, in onshore southeast to easterly winds, with the large high pressure systems passing through the south of the nation and direction the persistent onshore flow. But the highs becoming larger and more dominant, they override the upper level and surface level troughs that once brought the flooding rainfall (as we have seen in recent days).


So the seasonal shift is unfolding before our eyes.

FORECAST

Moisture Watch Next Week - April 4-11th 2022

The moisture really gets swept out during the period with the likely area for moisture to remain deep is over the northern tropics and through the northeast tropics and low level moisture along the east coast via southeast to easterly winds. The drier air should remain over the southeast, eastern and southern as well as central inland areas of the nation. There could be a few ports of moisture coming in from the northwest Indian Ocean but these should have minimal impact with the backside of the large upper high kicking the moisture offshore. There will be moisture running through the tropical north and some of this may be drawn southwards into northwest QLD, but with the large high pressure system in play, this will suppress rainfall chances again.

Rainfall Anomalies - April 4th-11th 2022

Above average rainfall chances remain in place over the northeast of the nation with the persistent trough and potential for a tropical low to linger bringing widespread rainfall through the Gulf and into Cape York. Most elsewhere, though it is a dry forecast for most areas across the inland, this is quite normal and so no deviation to drier or wetter than normal is the right forecast. So it is what we call benign Autumnal weather which is great for those on the land getting things sorted ahead of the approaching seasonal changes into the cool season.

Temperature Anomalies Next Week - April 4th-11th 2022

Above average temperatures over the southeast of the nation and extending through central and eastern inland areas of the nation. The northern tropics also looking near to above normal with higher humidity values. Seasonal weather conditions over the east coast with onshore winds and the chance of showers. The weather over the west coast is expected to remain near seasonal for the most part, though eastern districts and through the central and northern interior regions could be leaning above average.

DATA

Refer to the video for more information to gather context on this current guidance.


18Z GFS Surface Pressure Pattern and Rainfall Distribution - Next 16 Days

Noting that the pattern breaks down it appears if this is right from about the 10-12th of April onwards for southern Australia, but we have seen the bogus systems on the GFS in the medium term. Just something to watch for now.

18z GFS Precipitable Water Anomalies - Next 16 Days

Moisture is very limited in the short to medium term for much of the south and southeast/eastern inland with rainfall strictly coastal through the nation. The deepest moisture will be found over the northeast tropics.

12z GFS Rainfall Accumulation - Next 16 days

12z CMC Rainfall Accumulation - Next 15 days

12z Euro Rainfall Accumulation - Next 15 days

More to com e in your state based forecasts this evening.