NATIONAL WEATHER PICTURE - EVENING EDITION - TUESDAY MAY 18TH 2021.

Headlines


  • A quiet day nationally with high pressure the main weather feature.

  • Isolated thundery showers continuing out west this evening

  • Showers developing about parts of the NSW coast.

  • More frost and fog developing for eastern parts of the nation.

High pressure has been dominating the past few days, today is no different. Many areas in sunshine and clear skies, with light winds, that will be theme for many as we track through this week.


Rainfall for the next 10 days - the bulk of the rainfall over southern Australia falls in the day 8-10 window. Valid Tuesday May 18th 2021.



A weak trough in WA has kicked off a few showers and thunderstorms over recent days, and once again this afternoon, but overall it has been patchy, random and scattered for the region, with the trough now getting a kick along to the east by a front over the southern ocean.


Showers have formed in southerly winds offshore the NSW and QLD coasts during the last 24 hours. They have mainly been running parallel to the coast in southerly winds, but as mentioned the guidance is swinging them onshore over coming days as a southeast to easterly wind shift establishes as the high parks itself into the Tasman Sea.


And more frosts are on the cards for Wednesday morning, the run of below average night time temperatures set to continue over the coming days, with an elevated fog risk too for regional areas.


National Satellite Picture - Tuesday May 18th 2021. Sinking air motion under high pressure keeping large parts of the nation free of cloud and leading to cold nights and sunny days.

Clusters of thunderstorms are active over the west coast, but they are scattered, random and will feature heavy rainfall and gusty winds, but no severe weather is expected at this time. Satellite Picture - Valid May 18th 2021.

Thunderstorm Forecast for the remainder of Tuesday.

Over in the southeast, it is cloudy and cold once again as more low cloud is drawn over VIC and SE SA with these persistent westerly winds. Conditions should remain cloudy for a few more days until the high moves east and north during late Thursday into Friday. Weekend fans will have plenty of sunshine to play about in.


If you are away from VIC and SE SA you can see things are nice and clear with loads of sunshine.

Overall the pattern is largely unchanged in modelling tonight for the coming week with a high still going to be slow moving to the east before a new long wave begins to form over WA sending up a few cold fronts into the region by the weekend and into next week. Strong winds and showers will bring a much colder change to the west and warmer weather ahead of that is anticipated in dry northwest winds over southern and eastern Australia in advance of those fronts moving east mid to late next week.


The other area of note is the shower activity for the eastern seaboard rotating around high pressure over the Tasman Sea bringing in some moist onshore easterly winds. Rainfall totals will be light to moderate but could accumulate to 20-35mm for the coastal areas north of Newcastle to about Noosa.


GFS Flow pattern at 18000ft showing the slow moving high being knocked out of the region next week, opening the door up for that pattern flip mid to late next week, with rainfall signals increasing as we go through the end of the month. Valid Tuesday May 18th 2021.

Then the SAM trending negative begins to show itself in the short term forecasts with more frontal weather moving through southern parts of the nation. You can see the fast flow pattern trying to establish itself towards month's end into June with rainfall starting to pick up over the west and south of the nation.


Rainfall for the next 2 weeks - Valid Tuesday May 18th 2021. Raw data from the Global Forecasting System. Understand that these charts have been and will continue to throw a lot of colour around in the coming days, so keep these images as not a forgone conclusion, but more as a signal.

Temperatures have been well below average for the past week over eastern Australia with a continuation of this for the next 48hrs as the high takes it's sweet time to move east. That will lead to more locally severe frosts over southeastern Australia, particularly over the ACT and adjacent slopes and mountains.


Frost Risk for Wednesday Morning - Valid Tuesday 18th May 2021.



Fog will also increase in coverage in the coming days as winds veer into the east, and this could see some travel delays at airports over the east and south through later this week into the weekend, so just be prepared if you are leaving your home town via plane.


Fog Risk for Wednesday Morning, Valid Tuesday May 18th 2021.

I have updated the climate outlook for longer term conditions for Australia coming into June. For now it is very quiet weather wise which is nice for me, gives me time to prepare for the wild weather that could start to build in the coming weeks.


Need more information? Well the time is now, while the weather is quiet, I can provide you with more weather information tailored for you. Email me at karllijnders@weathermatters.org

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