SA - COLD WITH SHOWERS OVER THE SOUTH AG AREAS CLEARING WEEKEND. RAIN NORTHEAST AND WEST NEXT WEEK

The pattern is cold and unstable with a broad area of low pressure over the state with southerly flow running over warmer than normal SSTs across the state leading to showery periods for areas exposed to this flow pattern, particularly downstream from the wind bearing, leading to some areas seeing 5-10mm and some missing out all together over the coming 24hrs. That is how it has worked and will continue to work, connected to the wind bearing and position of the shower streams.


Elsewhere through the state, the rainfall is forecast to be lean with high pressure nearby and that cold airmass leading to chilly nights and dry days. This will continue through to next week.


Now over the northern parts of the state, an upper trough will move east and tap into moisture streaming in from the east via onshore winds over QLD, and we start to see cloud increasing during Monday into Tuesday with patchy rainfall possibly spreading through the NE during this time. It is a low chance (not 0%) of the rainfall spreading into the eastern border areas down as far as the Riverlands so will keep watching.


While the rain event gets going over QLD and NSW, a strong cold front will move into the southwest of WA and spread eastwards and on the northern flank of this, we could see a fairly deep moisture plume feed a cloud band, with areas of rain moving from WA into the west of the state by later next week. This again will be watched very carefully as timing, scale and speed of this system and whether we see moisture in phase with the front is key to whether we have rainfall return to Ag Areas next week.


I am leaning towards this occurring.


Let's take a look

FORECAST

Rainfall Next 10 Days

Mainly light to moderate showers with small hail is forecast to continue for the Ag Areas overnight and through Friday with the better coverage over the southeast of the state and across the Adelaide Hills into the Mid North. The shower coverage starts to decrease into Saturday before clearing on Sunday. The pattern dries for the whole state from Monday, but we could start to see rainfall return to far northeast areas later in the day as an upper trough deepens. Tuesday through Thursday we should see rainfall over the region’s north and east and rainfall and cloud will approach from the west Thursday and Friday. Timing of both rain events makes it very tricky to see whether they complement or compete with eachother so will be watching closely.

Frost Risk - Friday and Saturday morning

Temperatures could drop to 0-3C over the Flinders Ranges leading to pockets of light frost developing which may cause some issues for those planting throughout the region.

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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