SA - STRONG COLD FRONT TO BRING SHOWERS AND THUNDER - DRY WEEKEND. NEXT WEATHER MAKER MID WEEK.

The weather is certainly interesting across the region, and highlights how often SA is in the swing zone and why it often can sit in between the best of weather systems blasting through in the westerly wind regime during this time of year.


That said after heavy falls during the week north of the Ag Areas, the region north of Port Augusta is sitting pretty, it is areas to the south that need some moisture and could get a little bit during Friday and Saturday morning as then cold front moves through.


There is a broad risk of thunderstorms across Ag Areas on Friday, but I wouldn't get too carried away with heavy rainfall emerging with these. I do think we will see elevated thunderstorms but they will drop brief moderate rainfall but likely to increase in size and productivity the further east you are.


As we move into the weekend proper, I think many areas will be dry with the tail of a cloud band moving eastwards into NSW during Saturday. The weather over southern parts of the state will be cloudy with westerly winds and a few light showers and drizzle is possible but more nuisance value.


Next week, starting out drier and sunnier with milder conditions developing but not as warm as this current airmass.


A cold front is then expected to surge north through the Southern Ocean and start to make impact on the state from Wednesday and this is when we could see better shower coverage as that system moves through. Now the location of this upper level cold pool following the front will determine the orientation of the system and how much rainfall develops for those needing some rainfall.


So lets take a look

FORECAST

Rainfall Next 10 Days

Rainfall is forecast to be fairly widespread from Friday but the coverage likely to be light and therefore not much is expected through this system rolling through. The better rainfall may exist with the jet stream cloud band that will be running over the Mid North and Flinders and into NSW overnight into Saturday morning. Conditions dry out from Saturday afternoon. From Sunday through to mid next week no rainfall is expected. Another weather maker is forecast to approach from the south during Wednesday and showers and storms are likely to develop through southern and southeast Australia but the specific impacts on the state remain to be seen but certainly will be watching closely through the coming days over the weekend. Zoomed in charts for the southeast will be prepared if the rainfall event next week gathers pace.

Thunderstorm Forecast Friday

Thunderstorms are forecast to develop along and to the east of a frontal boundary that will push over the EP during the morning and reach Adelaide by lunchtime before spreading further east during the afternoon and evening. Elevated thunderstorms are likely to be present amongst a developing cloud band with spot moderate bursts of rainfall but totals should come away mostly light and below 10mm. Gusty winds and heavy rainfall leading to flash flooding is possible over the Victorian Border but I suspect that most of it will be east of the border.

Damaging Winds Risk Friday

Thunderstorms may produce damaging winds later in the afternoon along the eastern border with Victoria, ignition may be found along the backside of the Adelaide Hills to the southeast.

Flash Flood Risk Friday

Flash flooding a low risk along the Victorian Border during the afternoon and evening. The bulk of the severe weather should contract east after dark if it forms in SA.

MEDIUM TERM - May 6th- 13th 2022

Rainfall Anomalies

The rainfall bias has shifted to the east in recent broader guidance, given that we are seeing more drier and cooler air sweep the country. I am suggesting rainfall will be more aggressive over northern and eastern areas of the nation with the SAM tending back positive and with the lingering moisture courtesy of the lingering La Nina, the potential for a rainband to form in the north and east is quite likely. The west and remainder of the south seeing seasonal rainfall expectations. But the door is open for moisture to sweep south and southwest into these areas as well so watch closely.

Temperature Anomalies

A much colder signal has been triggered on the models with all in agreement we could see some quite fresh air being transported behind a strong cold front mid next week leading to the first chance of snowfalls on the mainland and the chance of frost for southern Ag areas of the nation so growers beware. The only thing offsetting the risk of severe frosts is that the SSTs around the nation are above normal and we do have a positive SAM phase unfolding in the east so while watching trends closely, there may be the chance some frost issues we could be talking about in around a week's time for the medium term.

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

A fast flow pattern unfolds this weekend with the strong cold front passing through. Then drier weather will resume for much of the nation. Next weather makers to watch are the southern system coming through over the course of mid next week. GFS dropped it tonight but the broader data sets have it. The other system to watch is the inland moisture building over northern parts of the country. Will that spread southwards into the medium term and provide the next inland rainfall event? Rainfall also picking up over WA in the medium term as well which could run across the country into the middle of the month so lots happening.

00Z GFS - Precipitable Water Values - Next 2 Weeks

Moisture is deepening over the east again ahead of a front passing through over the coming 36hrs but then it is out the door by Sunday and normal conditions resume for much of the country. As we track into the next week, we should start to see moisture building over northern areas of the nation and this could start to drift southwards and spread through the NT and QLD. Some of the medium term models want to spread that further south while other models spread through the moisture eastwards into QLD and NSW.

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 - once we get the weekend system off the board I fully expect some pretty impressive rainfall events to appear on the charts, but being cautious and explaining those details is key to keeping expectations in check. So low confidence forecasting continues beyond the weekend system.

More coming up from 8am EST. Will be updating the climate picture from tomorrow too into mid June. Plus a review of the severe weather risks for this weekend as well over the east. A few days to take a breath next week which will be nice!




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