NSW - SHOWERS MOVING EAST ALONG A WAVE - DRIER WEATHER DEVELOPING INLAND, SHOWERS ALONG THE COAST.

OVERVIEW

A deck of mid and high-level cloud is starting to move into the state’s east tonight and we have seen some dribble showers moving through VIC today, they will move over the inland and further east overnight into Wednesday. Along the coast, a trough will deepen as the inland feature moves into it, leading to more widespread rainfall developing for coastal areas between Jervis Bay and Port Stephens.


Inland areas dry out from mid to late week and the east coast will see a reduction in showers as all the unsettled weather begins to move towards the Tasman Sea and high-pressure sinks into the state.


The weekend looking much more settled with brighter days and warmer weather.


SHORT TERM

So, the system moving through tonight and during Wednesday will move on by during Thursday and conditions from that point dry out for the state. High pressure becomes the ruling feature as we move through the outlook period over the weekend and into next week as frontal weather begins to creep northwards through the south and southeast of the nation.


Through next week, moisture is set to increase in coverage as we start to see more unsettled moving northwards through the Southern Ocean and begins to interact with the warmer moist air of the jet stream.


LONG TERM AND AREAS TO WATCH

So that dictates what will likely be an active end to the month for Southern Australia, as we track a wave of low pressure through the Southern Ocean and this links in with warm moist air from the jet stream. We need the lifting mechanisms via the cold fronts leading to more widespread rainfall events sweeping the nation.


Overall, the rest of northern and eastern Australia looks dry with gusty easterly winds, but eventually moisture will begin to surge south from north of the NT and QLD and come southwards into the eastern inland too where we may start to see additional rainfall form under this cloud.


So, we will be watching the SAM to see if that trend more negative as I suspect it will launching those frontal passages further north and the moisture coming into the jet stream from the Indian Ocean.


WEATHER VIDEO PM - TUESDAY 12TH JULY 2022

FORECAST

Rainfall Next 10 Days

Rainfall looks to increase over the east coast during the coming 24hrs with another trough working northwards towards the NSW and combining with a very weak upper feature moving through from the inland. Showers increasing for the east coast with the chance of some thunder offshore. The bulk of the wet weather over the inland should be gone by Wednesday afternoon and the coastal areas should see clearance by the weekend. The next weather makers look to be further south through southeast Australia with frontal weather developing. Some chance we see a low-pressure form near SA next week and if that does evolve, then rainfall over the inland will come up but for now I am not drawing that in and want a few more sets of data before I add more to the charts.

Showers will be more widespread about the east coast during the next 2 days and then return to areas near the Riverina and Southwest Slopes with a westerly wind regime returning.

The showers through this region should be out the door by the time we get to the weekend with a drier westerly flow returning.

Frost Risk Forecast Wednesday Morning

Light frost is possible along the Murray River with the risk of severe frost very low. Depends on the cloud cover and the winds tending calm as we move through the overnight period.

MEDIUM TERM FORECAST

NEXT 3 WEEKS

Moisture Watch Next Week

Moisture is likely to graduate further east through next week as we find cold fronts peaking over WA but weakening and sliding southeast through SA and VIC, but the impact will be dragging moisture through the flow pattern and thick cloud, scattered showers will continue. There is some chance a middle level cloud band may also develop in the battle zone between the cooler air and the warmer air and where the jet stream decides to set up. So that will be an element to watch for inland rainfall chances coming up.

Moisture Watch Following Week

Moisture may be pulled west through northern Australia via wave activity over the tropical areas north of the nation. A moisture feed that comes through the nation in the week prior may continue to be found over southeast and eastern Australia leading to higher rainfall signals. Another front approaching the SWLD of WA may also have a period of rain and strong winds thanks to a deeper moisture feed coming through the jetstream.

Rainfall Anomalies Next Week

Wetter bias remains over western parts of the nation and may sweep into the southern coastal areas of SA and into western VIC later in the period with a departing low to the east but this looking at the frontal weather that peaks over WA early in this period moving toward the east. Mainly seasonal weather elsewhere with drier air and fine weather over the north and east.

Rainfall Anomalies Following Week

The moisture feed along the jet stream is likely to feature and I am going to keep the wetter bias under that, as the thermal gradient tightens, and the flow pattern strengthens over southern Australia will cold fronts feeding off this. I do think we will see more widespread rainfall over southern areas but that may shift further inland as well.

Temperature Anomalies Next Week

I have trimmed back that warmer bias over the southeast of the nation as we could see a low-pressure system forming through the weekend, which could bring widespread showers through SA and VIC this weekend. That may interrupt the warmer weather spreading eastwards, but warmer weather is likely through the northwest and central parts of the country and a cooler bias will continue over the east of QLD.

Temperature Anomalies Following Week

The warmer weather is forecast to feature through the northwest and northern areas of the country and the colder weather trying to work northwards from the Southern Ocean. The tighter the thermal gradient, the more active the weather is likely to be, especially with the jet stream and moisture involved.

DATA - Refer to the video for further information.


00Z GFS - Surface Pressure Pattern and Rainfall Distribution - Next 2 Weeks

Refer to the video for further information and context.

00Z GFS - Precipitable Water Values - Next 2 Weeks

The moisture profile is very much unchanged in its spread with the frontal weather featuring through next week pulling upon the deeper moisture over the Indian Ocean and ramming it through the jet stream. The timing of the fronts to the moisture surging south determines the spread of rainfall across the nation. Watching the moisture over the eastern inland next week if we see high pressure linger east of Tasmania, we may see a deeper surge of moisture coming into the inland areas ahead of that moisture coming out of WA and SA which could see rainfall increasing rapidly in the forecasts all of a sudden for the eastern inland. Out west, some heavy bursts of rainfall with that deeper moisture along cold fronts may lead to flash flooding at times.

00Z GFS - Rainfall Accumulation - Next 10 Days

Refer to the video for more context and analysis

00Z CMC - Rainfall Accumulation - Next 10 Days

Refer to the video for more context and analysis

00Z GFS - Rainfall Accumulation - Next 2 Weeks

Refer to the video for more context and analysis

A closer look in - the rainfall along the east coast is mainly over the coming 2 days before clearing then we see the majority of the rainfall focus associated over the southern and mountain areas exposed to the westerly winds. There are some weaker signals for further low pressure to form over the southeast inland and possibly off the east coast again which will need to be watched closely. It is a messy forecast.

More coming up from 8pm EST with a look at the models and rainfall.




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