NATIONAL WEATHER PICTURE - SATURDAY MAY 8TH 2021

HEADLINES


  • Rain overnight through SA moving east into western NSW.

  • Clearing along the east coast

  • Warm weekend for many inland centres

  • Cold fronts starting to sweep the southeast of the nation.


Overnight rainfall of 5-15mm has been observed through parts of western and central inland SA. Many areas seeing their best rainfall in many weeks after a long dry spell.


The cloud has largely started to break up as the trough is encountering much drier air over the east of SA and western NSW, though patchy falls can still be expected from thick high and middle level cloud through to Sunday morning.


Satellite imagery - SA focus 08th May 2021

The broader national view shows the weather stabalising for large parts of the continent with high pressure edging into WA and a weak ridge over the east. A weak cold front is moving through southeast Australia today with showers about SE SA, Victoria and western Tasmania with mainly light falls.


National Weather Satellite for Saturday morning May 8th 2021.

Current temperatures are warmer than normal for a lot of the east with left over humid air being mixed out by a wind shift into the northwest and west today. Cooler weather developing over southeast Australia and a warming trend for the west coast leads into a warm week. Overnights remaining above average for large parts of the country until mid next week, when frost could return to inland areas of NSW and SA.


Temperature anomalies for the next 10 days from Tuesday 11-21 of May 2021. GFS Valid as of May 7th 2021.


Temperatures remaining above average over WA with high pressure dominating the region with dry easterly winds and sunny skies leading to a warm and dry week after that very wet start to the month. Interior parts could have cloud from time to time and a drier airmass move in later next week as high pressure drags cooler in from VIC and NSW via southeast winds.


Warmer than normal weather for the SWLD for the coming 10 days from Tuesday the 11-21 of May 2021. Weather may start to turn around mid to late in the period, but no brutal cold weather is anticipated at this time. GFS 18z temperature anomalies for May 11-21. Valid May 7th 2021.



Rainfall for the next 10 days now becoming much more lean and restricted to coastal areas with the pattern flip underway over the west of the nation. The last of the inland rain will be gone by tomorrow for SA and so this will lead to a dry week for many over inland Australia.


Showers will increase for parts of northern QLD with easterly wind returning and some higher moisture values clipping Cape York in that regime with high pressure moving east over NSW.


A coastal trough off NSW will see showers increasing mid week with moisture from the onshore winds helping showers to increase through the Mid North Coast and Northern Rivers and perhaps into SEQ.


An upper cold pool may move in later next week with showers increasing over northern inland NSW and southern inland QLD with moderate falls but as per yesterday this is a LOW confidence forecast and we won't know more about that until really tomorrow night or Monday.


Cold fronts are now looking to be shunted a little further south over the coming week with high pressure moving in a bit faster so rainfall numbers are coming down for parts of southeast Australia, but still, showery periods are likely for SE South Australia, southern and mountain Victoria and western and southern Tasmania.


Dry elsewhere.


Euro 12z May 8th 2021 - Rainfall for the next 10 days

An interesting signal has appeared on the latest Euro run at 10am this morning for heavy showers to develop early next week with a southeasterly change and trough moving up the NSW coast with higher rainfall for parts of the region. Because it is within the 4 day scope, it is something to watch, with showery weather returning with onshore winds from Tuesday.


Euro 18z run May 8th 2021 - Showing that heavy rainfall for southeast NSW with the trough moving through and unsettled weather over the NSW ranges with showers and thunderstorms. Something to watch.

GFS is not as interested in that solution but has unsettled weather for inland areas and showers over coastal areas of the SE and some light falls about which will be welcome for SA.


GFS 18z run for May 8th 2021 - Rainfall for the next 4 days

The flow pattern for the next 2 weeks shows the weather becoming more zonal. That is a more unilateral wind flow over southern parts of the nation with fronts moving west to east more regularly, however cold pools or upper lows do seem to be the flavour of the month, with a few cutting off and creating inland rainfall events, especially during the latter part of the period.


Upper heights right where they should be over northern parts of the nation with dry stable weather away from the far northeast of QLD where showers and humid weather redevelops over Cape York. That moisture will have little consequence on bringing rainfall into inland QLD during this time, with the upper wind pattern taking the moisture through the Tasman and into NZ for them to receive some rainfall.


GFS has a big bowling ball long wave moving through the Great Australian Bight at the end of the run. This will likely change next run, however signals for rainfall increase through southern Australia from about the 22nd of May with a wet end to the month likely for many locations so this is the next period to watch for rainfall from WA, SA through to southern and western NSW, into VIC and Tasmania.


GFS 500mb flow pattern (18000ft) showing the upper level systems still appearing on charts which will have large impacts on rainfall distribution over inland areas if they verify, especially over eastern Australia. These systems can be the catalyst for east coast lows to form and bring severe weather to eastern QLD and NSW until the end of June. We are still in east coast low season. Valid May 8th 2021.

The precipitable water values show the increase of moisture for parts of FNQ and Cape York with easterly winds developing, however the upper winds, shear that moisture off to the southeast and little impact is expected over inland QLD and NSW for rain to return from this.


Showers may redevelop over the NE Top End with moisture values increases with easterly winds returning, but drier air for the remainder will keep the dry season developing and increasing over the coming weeks.


Relatively dry air coming up from the southern ocean will rotate around high pressure for the coming week, with the northern most part of a long wave trough with a few frontal systems embedded within the flow moving through southeast Australia. Behind each front, a shot of dry cold air will move north and east through the region, rotating around the high and extending to most of inland Australia by late next week.


That will keep rainfall chances lower as we go through the coming week for all inland areas away from the east, where this is a LOW chance of inland rainfall developing near an upper low.


The moisture values begin to improve from the west towards the end of the period with moisture returning from the north and west via the jet stream through the Indian Ocean. Any shot of cold air or upper low that can move into the jet stream will help initiate a large rainfall event over inland Australia that will move east. Something to watch.


Otherwise near seasonal values for the period, with the westerly wind flow bringing low level moisture to the southeast coastal districts for low topped showers and drizzle periods.


Precipitable Water values for the coming 2 weeks - ending May 23rd 2021. GFS 18z run valid May 8th 2021.

GFS keeps the dry look going apart from a pocket along the NSW coast, which is in line with the climate outlooks, but rainfall will return for the region leading into the latter part of the month with the return of a long wave trough over the nation.


GFS Rainfall Anomalies - deviation from normal measured in inches - Valid May 8th 2021

So the overall period is becoming more benign this week, with only a few areas of weather to watch.


  • Southeast Australia where showers and windy conditions will develop over the next week.

  • Southeast NSW where an upper trough might combine with moisture to produce heavy shower activity early in the week (LOW CONFIDENCE)

  • Northeast NSW and SE Q showers increasing with onshore winds developing. Upper trough may produce heavier falls later this week.

  • Chance of inland rainfall developing for Southern Q and Northern NSW with a stalled upper trough or cut off cold pool moving north through the eastern inland behind a fast moving front (LOW CONFIDENCE).

As always head to the forum and keep the conversation going there and if you want more tailored forecasts or to set up a weather chat with me to talk about your needs and the season ahead - email me at karllijnders@weathermatters.org


Next update - Sunday May 9th 2021



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