NSW - SHOWERS ALONG THE EAST COAST CONTINUES - BUT THE WEATHER SHIFTS BACK TO SEASONAL EXPECTATIONS.


OVERVIEW

Showers along the coast are expected to continue this evening and into Thursday but mainly along the exposed coastal fringe where we find an unstable southerly flow. The rest of the state is starting to clear as we see a high-pressure system moving through the nation and clearing the eastern inland.


Frosty nights and sunny days are forecast to return for the remainder of the week over inland areas. That may also continue into the weekend, offering at least a chance for areas to dry out a tad.


SHORT TERM

Showers are forecast to return however later this weekend to southern and southeast areas about the mountainous country. The showery weather may be light but could also increase if the low-pressure system lifts further northwards than what is projected, so understand there is some significant uncertainty surrounding this feature from Sunday into next week.


Stronger cold fronts begin to line up the south and southeast of the nation as a westerly wind belt begins to shift northwards and moisture is forecast to be featuring through the jet stream, there is some chance we could see widespread cloud cover and rainfall emerge as well north of this westerly wind belt.


LONG TERM AND AREAS TO WATCH

So, the westerly wind belt is expected to drive the wet and windy weather over the southeast with some of that working into NSW. But the better coverage of rainfall is likely to be over southern and southwest areas of the country where cold fronts may begin to tap into moisture drawn in on the northwesterly flow.


The heaviest of the rainfall looks to be over the SWLD of WA and western TAS where these areas are exposed to the westerly wind belt.


What makes this period more interesting is that the moisture is expected to feature on the northern flank of the westerly wind belt which may see rainfall chances move inland of WA, SA, VIC and into NSW and possibly moisture building over QLD as well, with a wetter signal building into the medium term.


WEATHER VIDEO PM - WEDNESDAY 13TH JULY 2022

FORECAST

Rainfall Next 10 Days

Apart from the heavier showers along the east coast of the state tonight and tomorrow with local thunder, the weather is set to clear from the west as we see high pressure moving into its Wintertime position. This is going to support the drier signal for many over the coming week including the east coast. Frontal weather is expected to move in from the west through southeastern states and some of that may clip the southern parts of the state with showers on the windward slopes next week. Coverage of the rainfall may increase next week but through deep troughs of low pressure working through the eastern inland or via strong cold fronts bringing in moisture from the Indian Ocean remains to be seen.

Showers could still be heavy at times about the coast tonight and again tomorrow morning with a few thunderstorms, but the rainfall forecast broadly under 15mm for many with a few getting over 35mm with thunderstorms.

Thunderstorm Forecast Wednesday night into Thursday Afternoon

Bands of showers with the risk of thunder and small hail continues tonight and tomorrow before the trough and unstable weather begins to lift eastwards. The rainfall is forecast to ease later Thursday.

Frost Risk Forecast Thursday

Frosts are likely over wide areas of the nation during Thursday morning where frost could turn severe during the morning about elevated terrain and the slopes as well as the colder pockets. The frost should clear by 9am.

Frost Risk Forecast Friday

Frosts developing in a widespread manner on Friday morning with the chance of freeze conditions developing over the southeast of NSW and the ACT where temperatures could get down as low as -9C during the morning. This will do damage to crops, cause issues for exposed stock and burst pipes. Ensure you are prepared.

Freeze Risk Forecast Friday

Significant risk of freeze conditions where pipes will likely burst under these conditions, significant damage to crops and vulnerable plants and stress to livestock.

MEDIUM TERM FORECAST

July 20th-August 4th, 2022

Moisture Watch Next Week

Moisture is forecast to stream through the jet stream via the Indian Ocean in advance of a long wave trough which will likely see the frontal weather associated with this wave of low pressure producing more widespread rainfall thanks to the injection of moisture. This will waft across to SA, VIC and NSW with high cloud and patchier rainfall. The east could see increasing moisture in onshore winds which may produce a few showers.

Moisture Watch Following Week

Moisture running through a lower latitude easterly wave could be drawn through the north of the nation into QLD in advance of the long wave trough exiting eastern Australia. Some cloud and rain are possible. Another set of cold fronts will drag in moisture from the Central Indian Ocean and lead to further seasonal rainfall expectations for the west and south of the country.

Rainfall Anomalies Next Week

The rainfall is now moving into the short-term forecasts with a lot of rainfall now likely in the coming 10 days. There will be frontal weather moving through SA and VIC through this time, but it is likely that the rainfall will meet seasonal expectations at best and nothing more. Further frontal weather passing through the SWLD may produce further widespread showers and a leaning above average signal of rainfall.

Rainfall Anomalies Following Week

Likely to see a tighter thermal gradient develop and this could lead to more unstable weather, with moisture running through the jet stream, I do suspect we will see more rainfall developing across the nation, especially as the wave passes through from west to east. A low chance of rainfall lingering over the eastern coast of NSW as well.

Temperature Anomalies Next Week

A warmup is expected from the weekend and increasing next week as a result of the elevated SSTs offshore NW Australia is filtering through ahead of cold fronts slipping to the southeast. A warm northwesterly flow will start to distribute this warmer signal into the eastern inland later next week, but it is hard to determine how warm it will get, as moisture looks to be sufficient for large scale cloud bands to form on the northern flank of the fronts as they pass southeast of SA and VIC. This may suppress temperatures.

Temperature Anomalies Following Week

The warmer bias is still expected to graduate northwards as a long wave trough starts to move through southern and western parts of the country. The clash zone between the colder air surging north and the warmer air increasing over interior regions will be an area to watch as the jet stream is likely to intersect this zone and with moisture increasing over the Indian Ocean, there will be a higher chance of rainfall building through the forecast period.

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 for all the information on the short and medium term plus why the weather is so complex and what to look out for.

00Z GFS - Precipitable Water Values - Next 2 Weeks

Moisture is leaving the east and increasing out west as we see a pattern flip on the go across the country, with the drier and seasonal air continuing over northern Australia. We see moisture return over the south and southeast this weekend with a weak front moving through with patchy rainfall and cloud. Then we see further regular shots of moisture running through the jet stream and that then trying to get into phase with the wave train moving over the nation. The wild card is the relationship of the moisture and the frontal weather. That theme will continue to feature more frequently as we move into August.

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 - rainfall is all over the shop for NSW and QLD so that rainfall there post the east coast showers tonight and tomorrow is low confidence. Rainfall then returns to southern Australia and with the low confidence due to the complexity of the pattern, means the door is open for the rainfall number to increase over pockets of southeast and southern Australia in future updates so keep close to the forecasts.

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




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