MODELS AND RAINFALL - INLAND AREAS LOOK DRY BUT WE COULD SEE INTENSE RAINFALL OVER THE TROPICS.

The weather certainly looking benign for many inland areas with broad high pressure and dry air in place. But if you are looking for rainfall you will have to live over coastal areas of the south, east and over the tropics for the really big numbers through the outlook period.


In terms of the medium term, still eyeing off the moisture over the north of the nation, looking at the current synoptic pattern, that does appear to drift east with the southern pressure pattern looking to favour that solution.


Moisture in the Indian Ocean may then be allowed to make it towards the SWLD of WA and once again bring more above average early onset rainfall for the region, as forecast here back in February.


Will the rainfall make it further east in the long term?


Lets take a look


SHORT TERM

Certainly looking wettest over southern coastal WA and this may send dribbles into western SA. Over the southeast, light showers tonight will move up the NSW coast during the coming days and join the onshore winds and showers over eastern QLD with light to moderate rainfall totals overall through Friday. The really big numbers nationally will likely be found over the northern tropics. Some of the rainfall over the north could tend very much above average if a tropical low forms. We could see a band of rain push through southeast parts of the nation across VIC and TAS with a front early next week.


UKMET - Rainfall Next 5 Days

The modelling showing rainfall building through the southwest over the short term and then another trough deepening over the Bight during later Friday. Rainfall increasing over the northern tropics but not as amplified as other models. The remainder of the nation's interior looking very dry and stable through the coming 5 days.

ICON - Rainfall Next 8 Days - LOW CHANCE

The latest German model is showing a front developing next week with a band of rain forming over Easter Monday and then spreading eastwards thereafter. The tropical moisture over the NT adopts a west or southwest track and then becomes ingested into the jet stream lifting rainfall chances across the nation from northwest to southeast under this guide. Dry over the eastern inland.

MEDIUM TERM

Watching the development of the moisture over northern Australia and at this time, it does appear to adopt an easterly track and likely not to have high impacts on Australia, but will be monitored as these forecasts can be rather fickle when related to tropical weather in this region. Moisture building through the Indian Ocean may come across to the west coast with a deep trough also forming with the moisture to produce a large cloud band. This may bring some rainfall through southern coastal WA and into the Bight. At this time, the impact looks minimal for areas further east.


CMC - Rainfall Next 10 Days - LOW CHANCE

Showing heavy rainfall over the southwest of the nation in the short and medium term with two events in this period. Rainfall not as amplified over the northern tropics but certainly above average rainfall, but not as widespread as other models below. Dry weather for large chunks of the east and southeast.

EURO - Rainfall Next 10 Days - MODERATE CHANCE

Showing that excessive rainfall of nearly 700-800mm over the NE Top End with the tropical feature so that is something to watch. Tracking that rainfall over WA in the short term then another wave of low pressure leading to a band of rain forming mid next week. Dry weather for the east and southeast with ridging.

ACCESS - Rainfall Next 10 Days - LOW CHANCE

Showing the rainfall and tropical weather heading east rather than west leading to heavier rainfall for FNQ QLD. The rainfall over southern WA excessive and related to the event in the short term and then another next week out of the Indian Ocean. The east coast seeing seasonal rainfall expectations. Some of the moisture will likely arrive under this guide into SA from mid next week.

KMA - Rainfall Next 12 Days - LOW CHANCE

Rainfall over the north nowhere near as amplified as other models but there is a signal that the moisture would escape through the Indian Ocean and turn south and southeast. This idea would see better rainfall odds for WA and into SA next week. The east would be dry with a ridge further east with above average temperatures and reduced rainfall chances for the east coast.

GFS - Rainfall Next 16 Days - LOW CHANCE

This forecast is running too dry for inland areas I suspect and the focus is heavily on the tropical mischief over the north. This is showing 1.5m of rainfall for the eastern Top End. So this forecast needs to be taken with a grain of salt for now. But the rainfall over the WA Ag areas looks to be gathering pace for next week and a front over the southeast early next week could bring light falls and additional light falls to the east.

ENSEMBLE DATA

Rainfall areas are identified as northern areas, through the southwest of the nation through the short and medium term and across the southeast and eastern coastal areas. Regions that look to miss out are expected to be large parts of the inland of the country for now, but moisture wafting over northern Australia at this time of year is not modelled very well at all.


GFS - Rainfall Next 16 Days (median of 35 members) - MODERATE CHANCE

Rainfall not as excessive as the deterministic above and that is to point out that some members are seeing heavy rainfall and some members are not. So there is still some error in the forecast that needs to be monitored. The west seeing another round of rainfall next week is gathering pace on the charts and the east coast seeing seasonal rainfall, as is the southeast coastal areas, back through southern SA but no major Autumn Break at this time.

CMC - Rainfall Next 15 Days (median of 30 members) - MODERATE CHANCE

Noting the weather over the east is drier than previous months which is good. Not as aggressive on the WA rainfall chances but noting that the weather over the northern tropics is well above normal.

EURO - Rainfall Next 15 Days (median of 51 members) - MODERATE CHANCE

Rainfall is excessive over northern areas with a good chunk of the 51 members supporting above average rainfall for the tropics. Some areas could see the April average 10x over looking at the data. East coast sees showers but severe weather potential looks low for the coming 2 weeks. Weather in the west looking wet with above average rainfall likely. Some of this may shear off into the southeast by ANZAC Day. Inland areas looking mostly dry under ridging.

LONG TERM

The rainfall will return to southern and eastern inland parts of the nation. Rainfall totals still look to be above average through this period for many southern areas, especially over the southwest. Across northern Australia, rainfall should begin to decrease during this period with the tropical wave/low/cyclone moving away and drier air beginning to take hold again. A positive SAM phase or two to bring enhanced rainfall to eastern Australia is also possible through to Mid May.


CFS - Rainfall Next 6 Weeks - MODERATE CHANCE

Do not rule out the tap being turned on into May and we may be looking drier for the short term, but I am fully aware that we are still dealing with a waning La Nina, elevated SSTs around the nation and a wet season peaking at near record levels in the coming fortnight for some areas.