NATIONAL WEATHER PICTURE - EVENING EDITION - MONDAY 24TH MAY 2021

Headlines


  • Showers and storms easing over WA. First frost on the way Tuesday.

  • Rain developing over SA and VIC overnight into Tuesday.

  • Rain developing for southern NSW on Tuesday.

  • Severe weather potential for WA this weekend.

It has been a bitterly cold day over WA with widespread showers and thunderstorms over the southwest and southern coastlines. These have started to ease throughout this afternoon and winds are starting to ease as well. The light winds and clearing skies, combining with the cold dry airmass over the inland will lead to a frost risk this evening.


Over SA and VIC there has been a steady increase in the cloud cover with a fresh to strong and gusty northerly flow. It has been a mild to warm day in that airstream and will be warm tonight ahead of the rain that will develop from the west.


Cloudy over eastern parts of NSW and QLD will continue to break up this evening with the heights coming up and the air drying out. High cloud has increased over parts of western NSW heralding rain developing from the west overnight and Tuesday.


Over the north, it is clear, warm to hot though humid with sunshine. Many in the Top End and Cape York will be hanging out for the next dry surge this weekend.


National Satellite Picture - Valid Monday May 24th 2021. 3pm EST.

A band of rain is expected to sweep through southern SA this evening and move into the southeast states during Tuesday with a warm northerly wind regime shifting into the west. Along that wind change, there may be some slightly heavier rainfall.


A closer look at the moisture being drawn into the front, shows a fairly wide band of rainfall over the Eucla and along the southern coast of WA in association with the coldest air that is riding north along the western side of the front. This area of colder air will weaken and slip south overnight.


In the warm sector to the north and east of the front, rainfall will steadily increase in coverage along the southern coast of SA and into VIC overnight, which you can see developing right now on the satellite.


Zoomed in Satellite view of the Great Australian Bight - Valid May 24th 2021. No rainfall is falling under the cloud over NW WA for now, but this moisture may come into play over the weekend.

Showers have been widespread through southern WA today with that cold air. Thunderstorms reported along the coast between Albany and Esperance with some moderate to heavy falls.


Radar imagery for the south coast of WA. Valid May 24th 2021 at lunchtime.

Rainfall for the event out west has been very useful and again adding to a very wet month of May for the region. That was well picked by climate models ahead of the month kicking off. Some areas have seen over 100mm for the event in the SWLD.


24hr observed rainfall for WA - Up until 9am 24th May 2021. A few falls did exceed 50mm once again down in the far southwest.

The front and cold air is expected to weaken as I mentioned over the coming 24 hours, as it tracks east into a firm ridge over the east of the nation. That will force the system to move south rather than east, but it will still have enough moisture on it's northern flank to bring rainfall through to southern Australia with some moderate falls about those areas exposed to a northwest and westerly wind regime.


Upper flow pattern at 18000ft - Valid Monday May 24th 2021, GFS 00z Run.

Powerful front peaking over WA now beginning to weaken as it rolls into SA. Though a steep thermal gradient and modest moisture will see a rainband develop along this boundary as it moves through. Ridging in the east of NSW and QLD, holding firm and will lead to a warm day on Tuesday.

Upper flow pattern at 18000ft - Valid Monday May 24th 2021, GFS 00z Run.

Front now moving through VIC with moderate rainfall along the northern slopes of the Great Dividing Range and across the southwest. Some rainfall shadowing expected along the Central and Gippsland regions with a northwesterly flow through the region. Colder air with showers to follow the rain, more widespread over southwest VIC and southeast SA. Rain will likely be moving into southern NSW during this time, though light falls still expected.

Upper flow pattern at 18000ft - Valid Monday May 24th 2021, GFS 00z Run.

Come the end of this week that wave is on by, and we have high pressure back over Great Australian Bight waters. That will keep the onshore flow going over the east with cool conditions. A strong cold front moving through the Tasman will send a shot of cold air and showers along the NSW coast. Out west a new wave of low pressure will approach over the weekend with severe weather potential.


So rainfall for the next 3 days is largely southern coastal and focused over the southeast of the nation with moderate falls over southeast SA, VIC and TAS. Light falls for NSW as mentioned and no rainfall expected for QLD and northern NSW at this time. Conditions should ease over WA with a new ridge moving in.


Rainfall accumulation for the coming 3 days - showing the rainfall moving from the west now across the south and through the east. Not much rainfall is expected from that large mass of cloud over the interior at this time.

Rainfall anticipated for the coming 3 days - Weather Matters. More information has been shared today surrounding the weakening cold front moving over the southeast. Valid Monday May 24th 2021.

Out west, we will have to keep an eye on a developing low which may turn into a severe weather event on Sunday and into Monday with strong winds, heavy rainfall leading to flash flooding and damaging surf. Placement, timing and strength still be discovered on this system, so more information on that coming on Thursday, but it is a heads up for more wet and thundery weather coming over the weekend.


Precipitable Water anomalies and MSLP for Saturday through Monday next week. GFS 00z run valid Monday May 24th 2021. I will also mention that this system has been placed further west off Perth and cut off from the flow meaning it lingers for days. But GFS is an outlier, and not an unreliable outlier, given the westerly wind belt is close by, it could be absorbed into the flow and sent east rather than south. Will continue to monitor.

Rainfall forecast for the coming 10 days - this will bounce around a but for the west and south coasts, given the placement of the low will determine who gets exactly what and how heavy. That will become clearer over Thursday and Friday. Valid Monday May 24th 2021.

That system then looks to move east and south and will likely bring some rain and thunder to the southern parts of SA and then onwards into VIC, NSW and TAS in some manner, but again it is way too far out to be sure. But signals are positive for moisture to spread east and south from WA into early June.


Precipitable Water Values for the coming 2 weeks - GFS valid 12z Monday 24th May 2021.

Want more weather information for your part of the world? Email me at karrlijnders@weathermatters.org





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