EASTER SATURDAY WEATHER WRAP - WARMING UP TODAY BUT CLOUD STARTS TO BUILD TOMORROW OUT WEST&SOUTH.

The tropics also quite unstable with extensive showers and storms over parts of the Eastern Top End and Cape York where we are seeing a significant moisture plume being picked up by several waves. There is also a weak low that has developed in the Gulf embedded in one of the waves which is enhancing rainfall for extreme coastal areas with the bulk of rainfall sitting over the Ocean.


Across the rest of the nation today, mild to warm to start and for the western portions of QLD, NSW, northern VIC, much of inland SA and eastern and central WA, hot weather is expected to develop with a large upper high in full control leading to clear skies and dry air. At the surface, a high pressure system is forecast to remain in the Tasman Sea and this will work with the upper high and see a northwest flow develop, and as forecast a warm to hot Easter is unfolding.


Now as we get to Easter Sunday, cloud should begin to thicken over western and southern parts of the nation as a cold front begins to approach the Bight and this will set up a tight pressure and thermal gradient. So strong northwest winds for Easter Monday with a band of rain spreading from inland WA, mainly offshore SA and into the southeast inland. Some modelling has this band of rainfall sitting over VIC and TAS for the best part of 3 days but this has been an idea coming and going from the charts. Some modelling yesterday also supporting low pressure developing on trough itself so that could enhance rainfall and bring some surprise falls for some from SA through VIC.


The system should be on by during Thursday at this stage and drier weather will resume for most areas thanks to high pressure, but we need to watch closely offshore WA. There is another surge of moisture forecast to emerge and be injected into the jet stream. The jet stream also likely to be pulled southwards into a frontal boundary that is rearing up from the Southern Ocean and we are likely to see a large cloud band form with a much better chance of widespread rainfall developing from this feature around ANZAC Day for the west and spreading east thereafter.


With some luck, that could lead to widespread rainfall falling over SA and into VIC into the end of the month and giving those west of the divide through NSW and QLD a go as well, with some moderate rainfall. The models once again today pinging that system at the end of April and into early May but this will bounce around, be aware something is brewing but don't make decisions off poor data and apps. Get the forecast from human sources!


Looking at the temperature profile, we could see some significant cooler air developing behind the system as a more traditional mid Autumn pattern develops. This system may also assist in cleaning out the humidity and rainfall from northern Australia right on time for the calendar start to dry season.


Lets take a look


FORECAST

Rainfall Next 10 Days

The rainfall remains an area of interest running through this week. It may be Easter and it may be lovely weather for many locations, but lots of people will likely return to the new working week with rainfall underway and a cooler shift from SA through VIC and into southern NSW. There could also be some patchy falls through outback WA which will be connected to the northern branch of the cloud band. As we head through northern Australia, some heavier rainfall is still forecast about the eastern Top End and through Cape York over the coming 2-3 days before the weather begins to contract eastwards. FNQ could also see some late season falls which is important after a dry wet season for the region. Further into the medium term, we are still watching together this potential for an Autumn Break which may lead to enhanced rainfall and a colder shift in temperatures which is something we are yet to experience on a national scale. That will confirm the Autumn Break.


THUNDERSTORM FORECAST

Thunderstorm Forecast Saturday

Thunderstorms continue with above average rainfall chances for northern parts of the nation. Some of the storms could be severe about the Top End, especially in the east and around the Gulf Country with a deep low forming in a tropical wave.

Thunderstorm Forecast Sunday

Thunderstorms continue mainly about the Gulf Country of NT and QLD. Thunderstorms may be gusty at times. A weak middle level cloud band may form on Sunday afternoon in WA and graze southern SA and southwest VIC with the low chance of a thundery shower under it.

Thunderstorm Forecast Monday

Thunderstorms are forecast to emerge over the southeast with a cold front moving through Victoria and eastern Tasmania. Some of the storms could be gusty with moderate rainfall. Thunderstorms over the tropics forecast to contract further east but may increase in coverage if a tropical low forms near QLD. So this forecast is variable for northern areas.

Thunderstorm Forecast Tuesday

Thunderstorms will be a low risk under a cloud band over the southeast and mainly on the periphery of the cloud band. Thunderstorms will continue over parts of the northern tropics but more likely over Cape York.

Thunderstorm Forecast Wednesday

Thunderstorms should contract through NSW and eastern VIC with the departing rain band. Isolated showers and thunderstorms possible over the western interior near a weak trough and the showers and storms should contract east over Cape York during Wednesday where the higher chance of convective weather remains.

MEDIUM TERM - April 23rd-30th 2022

Rainfall Anomalies

Rainfall anomalies not changing that much for the period to end the month with a dry airmass being overrun by the moisture streaming in from the west, north and east. Now as I keep mentioning, do not get so caught up on the colours at the moment on the chart and on the medium term modelling with a few pieces of the puzzle to come together. However the higher chance of above average rainfall through the period will be found trough the northeast, east and southeast inland with the low pressure anchored through the region with the moisture. Your number will vary and chop and change from run to run. But certainly watching the long wave moving through western areas of the nation, the impact of the positive SAM and residual tropical moisture wafting about the north.

Moisture Spread

That moisture as mentioned above is broad and extensive, but needs to be in relationship with low pressure to bring rainfall or you just end up with a lot of high cloud and no rainfall, which has been observed through southern areas of the nation in recent days. There is low pressure to work with for the southern parts of the nation and in the east so pay attention to the forecasts here over the coming days. We may see more widespread rainfall forecast for areas that are trying to dry out but welcome rainfall could resume over areas of SA and VIC.

Temperature Anomalies

The cooler weather is spreading along the southern coastline of Australia through this time as a long wave trough passes through from west to east. Could this be the Autumn Break in terms of temperatures? Sure could be, with the warm airmass currently over us persisting through to ANZAC Day over central and eastern areas, but being swept north and east by a gusty and colder westerly shift. The depth of the cold dependent upon the wind bearing and the northward location of any low pressure that forms with this system.

DATA - Next video is due out on Monday. Have a great weekend.


12Z Euro Surface Pressure Pattern and Rainfall Distribution - Next 10 Days

12z Euro Precipitable Water Anomalies - Next 10 Days

Substantial moisture over the southeast via the jet stream (get used to hearing this for the next 6 months) with widespread cloud still likely to develop as a result through the week and rainfall becoming widespread where low pressure meets the moisture. The more interesting system sits in the end of the period, with the positive SAM phase increasing moisture from the east across much of the nation. A trough may link up with the moisture and as you can see above, the importance of low pressure in relation to the deeper moisture profile is crucial to excessive and above average rainfall. Frost risk very low through this period with a warmer and more humid airmass likely for many areas.

12z Euro Rainfall Accumulation - Next 10 days

Has a nice rain band developing through the southeast from later Sunday into early next week but moves it on a little quicker and a low tries to form on the trough but doesn't quite get there. Further showers developing along the east coast in onshore winds next week. The tropics begin to dry out as an upper high begins to build. Moisture deepens over WA mid next week and that will help form another rain band, that moisture drifting across and feeding another trough over inland SA with rain increasing over the long weekend. Moisture will also be drawn in from the easterly winds as well.

12z GFS Rainfall Accumulation - Next 10 days

Picking up the substantial rainfall over the southeast inland, but has shifted it more into NSW and the eastern and northern parts of VIC. So be aware that this event will wobble around. The heavy rainfall through the north is contracting eastwards over the coming days. Out west, another cloud band may develop from later next week with further rainfall. That moisture then sparks the rain you see in SA later in the period. But that system over SA carries low confidence.

12z CMC Rainfall Accumulation - Next 10 days

Has a substantial rainfall event for parts of the southeast inland starting Monday and easing by Wednesday or Thursday. Then the model struggles to place the inland low pressure trough next weekend and what to do with the moisture feeding in from the east, north and west into this feature so I think this particular model is out on it's own right now.

12z Euro Rainfall Accumulation - Next 15 days

Suggesting rather dynamic weather for inland QLD, NSW and VIC spreading into eastern and southern SA through the medium term in addition to the moderate to heavy rainfall this week over parts of the southeast inland. Showers and storms may return to parts of the east coast with the positive SAM phase and rain develops out west with another cloud band emerging. The tropics start to dry out away from FNQ.

12z GFS Rainfall Accumulation - Next 16 days

There are continued significant signals on the medium term spread of data for an Autumn Break to develop for parts of SA and into VIC through the end of the month, but timing, placement and orientation of the system will chop and change as we go along. But encouraging to see that additional rainfall in Ag areas is still quite likely through this period.

The tropics look to dry out a little bit and more rainfall coming into WA with another set of cold fronts or troughs. The east will see showery weather in the easterly winds thanks to the positive SAM in place.

Another update due out on Easter Sunday. Have a great long weekend!