NSW - COLDER AIR SURGES NORTH - RAIN EVENT NEXT WEEK IN QLD PROVIDES MOST INTEREST IN OUR STATE

The weather is continuing to turn sharply colder and over the past week I have outlined the Winter weather issues which is expected to remain in place. So morning frost is forecast to continue through the weekend before easing on Sunday and the farmers and grazier issues will ease by Saturday as new high pressure moves in.


In the longer term, as we move into next week, the more glaring weather event is the rain event in QLD. How much of that rainfall spreads south and west through the state remains to be seen but there does look to be promising follow up rainfall potential for large areas of the north and possibly central districts next week with the deep trough and upper low moving through.


As mentioned, the rainfall spread from model run to model run will continue to chop and change but understand rain and thunderstorms will continue over the state for much of next week with widespread rainfall along the coast via onshore winds another trough.


All hallmarks of a positive SAM phase.


Areas that look to miss out on the widespread rainfall from this event looks to be the far southwest and south of the state bordering Victoria, but even here, the chance of rainfall coming south is not 0% but it is fairly low.


Another rainfall event is forecast to emerge through WA mid next week along a strong cold front and there is growing evidence that a cloud band with areas of rain may form along this front with moisture streaming out of the Indian Ocean.


So, there is plenty on.

FORECAST

Rainfall Next 10 Days

Rainfall is forecast to continue over the northeast and far east on Friday as a weak trough continues to move north and east through the state in advance of cold air filtering north. The cold air over the inland may produce a few showers but overall the coverage is isolated. Now as we move into the weekend, the rainfall should clear much of the state and most areas should remain dry. It won’t be until next week that we start to see patchy rainfall developing over northern inland areas of the state from QLD and showers increasing along the coast in easterly winds. This mass of rainfall likely to grow by Tuesday through Thursday with moderate to heavy falls possible the further north you go towards the QLD border. Along the coast, widespread showers are forecast to emerge as we see onshore winds continue in the unstable airmass across the state. For far southern areas, the rainfall is forecast to be light and patchy at best with this feature. Later next week we have to watch the WA front with interest and see whether we see a moisture plume become entrenched into the system from the northwest with a broad cloud band developing. So that will bring up rainfall chances for areas that miss out with the rain event from QLD.

Severe Weather Watch - Tuesday through Friday

Flash and riverine flooding is possible next week as widespread rainfall falls over relatively wet catchments following months of above average rainfall. Rainfall rates could be heavy enough to cause renewed moderate flooding in some of the disaster zones.

Frost Risk Friday through Sunday Morning

Cold air trapped under high pressure combining with clear skies, dry air and light winds will assist in the formation of the first frost event of the season. No severe frosts are expected at this time.

MEDIUM TERM - May 12th-19th 2022

Rainfall Anomalies

With the bulk of the heavy rainfall event with the upper low now moving into the short-term forecast, the anomalies are looking less dramatic for the east though lingering heavy rainfall early in this period will continue for the east before easing and clearing. The north of the nation likely to see further above average rainfall potential with the SAM remaining positive sending in more humid northeast winds. Over in the west, the rainfall should be leaning above average through this period with the long wave trough settled over the region if not offshore producing cold and showery weather. Most elsewhere should be seasonal with a mixture of rainy days but mild sunny days too.

Temperature Anomalies

The cooler bias is unchanged over in the west with the persistent onshore flow with windy weather and showery conditions. The east warms up following the widespread high impact rainfall event. With the winds out of the northwest in advance of cold fronts and a ridge to the southeast and east of the nation, a warm tongue of air could become established over the north and east for a good chunk of this period.

DATA - Refer to video for more information and the model comparison and context about all the forecast products you see from me.


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

More information can be found in the video at the top of the page to cut down on your reading but overall, the cold outbreak continues to work through the southeast inland of the nation. The dry and warm weather over the west and north will continue through the weekend. A few showers and storms may also continue for parts of eastern and southeast QLD before an upper trough approaches from the west of QLD and that will lead to increasing rainfall and the high moisture levels will be utilised into widespread rainfall with heavy falls through next week with severe weather potential. Over in the west, a strong cold front also needs to be watched with severe weather potential with heavy rainfall and strong winds. That feature to become better modelled by the weekend. The medium term offers more frontal weather over the south and more humidity for the north and east. So the mechanics and ingredients for further severe weather is possibl

00Z GFS - Precipitable Water Values - Next 2 Weeks

The moisture content is somewhat below average over the southeast and southern parts of the nation thanks to a broad cold outbreak that is continuing to unfold across the region. The cold and dry air will stop short of moving into QLD but it will move through the remainder of the country. The moisture is forecast to deepen further this weekend over the northeast and this moisture will spread south and west overriding the drier air in place at the moment leading to elevated rainfall. The moisture will then spread through much of the south and southeast lifting rainfall chances next week for QLD, NSW and the ACT. The next pulse of deep moisture is forecast over the SWLD of WA leading to higher rainfall chances next week. Some of that moisture could make it across to southern parts of SA and then into the southeast. Moisture also creeping up over the northern tropics as well through next week and into the medium term and we have another shot of moisture coming into the jet stream from the medium term as well over WA which will too spread eastwards.

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 Euro - 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 to be highly variable from model to model and run to run and this won't settle down for a few days so expect more changes to come and refer to the broader updates here for understanding and analysis while we wait for more consistent data.

I am travelling tomorrow morning early to Darwin and will have the next video at some stage tomorrow. There will be weather information throughout the day so look out for that plus a climate refresher. Have a great evening!


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