FRIDAY EVENING WEATHER - IT IS ALL ABOUT THE RAIN IN THE OUTLOOK - IT'S OUT WEST ALREADY.

Updated: Jul 31

OVERVIEW

A strong cold front that brought the showers and thunderstorms into the southwest of the nation over the past 24hrs is now racing through Southern WA and into the Bight leading to a spread of rainfall through the region. Clearing conditions are expected further to the east and southeast of the nation as high pressure starts to move in.


A very cold night of weather is on the way with severe frosts and damaging frost possible for some areas. There is the risk of freeze conditions over the ACT and nearby surrounding regions of NSW and at elevation over the Central and Northern Tablelands. Domestic water issues may be experienced in these regions.


Most elsewhere, the weather is forecast to be relatively benign.


SHORT TERM

It is about the spread of westerly winds across the nation through the weekend, a while the mornings will be cold over the south and southeast, the northwest to westerly winds will help to transport the warmer weather over the northern inland of the nation into SA, VIC and NSW ahead of frontal weather that will bring some showers.


Stronger cold fronts may develop from the west during Sunday and a very strong system is expected during early next week with severe weather potential with this feature (more to come over the weekend with relation to this system).


The lead system over the southeast may invirgorate a weak trough over the eastern inland which will lead to scattered showers developing over southwest QLD into much of western NSW later Sunday and into early next week with the risk of local thunder. The rainfall will spread towards the coast by the end of Monday into Tuesday.


But all eyes on that strong system racing throughout the nation’s south through next week with rounds of light rainfall initially in gale force northwesterly winds for large areas.


A nasty piggy back system pushing through during Wednesday over the SWLD may lead to further severe weather issues with high impact gales and moderate rainfall with local hail and thunderstorms. That system will then bring the better rainfall chances back over SA and into VIC. Ahead of this feature, a large band of rain will break out over NSW and southern QLD with the chance of moderate to heavy falls on and west of the divide through NSW and nearby the ACT.


Showery weather will continue over the southern parts of the nation this time next week into the weekend with westerly winds continuing. Showers and thunderstorms may continue to feature along the jet stream and nearby trough over northern NSW and southern QLD extending northwest into Central QLD.


Further frontal weather is expected later next week out west.


LONG TERM/AREAS TO WATCH

It is a complex weather pattern developing throughout this period with multiple waves of low pressure interacting with the moisture spreading through the upper-level northwest winds. You can see that playing out right now through the west of the nation and that will be continuing to feature throughout the first 2 weeks of August.


Rainfall looks heaviest in areas exposed to the westerly wind regime and may lead to some areas seeing their heaviest rainfall since early June over southern Australia.


Areas of rainfall may develop over the interior with the jet stream active and moisture likely feeding in from the northeast and north, not just the northwest of the nation.


The Southern Annular Mode looks to remain in negative territory for the coming week and possibly into the second week of August.


WEATHER VIDEO PM - FRIDAY 29TH JULY 2022

FORECAST

Rainfall Next 10 Days

There is ongoing rainfall in the SWLD of WA with moderate falls about the coast tonight as the system that brought storms this morning moves away. Another set of troughs and shortwaves embedded in the westerly flow will continue to drive showery weather for the region this weekend but more likely to be focussed about coastal communities. The rest of the nation mostly dry through the weekend. We could see some scattered showers developing over the southeast and eastern inland with the lead system today running into SA and VIC and kicking off widespread showers along coastal areas there invigorating another trough over the interior. Lots of moving pieces with areas of rain about the eastern and southeastern inland to start the new week and heavier and more widespread rainfall developing over the west of the country with possibly, the strongest system of the Winter thus far. Widespread rainfall developing from Monday out west, and spreading further east Tuesday and then into the Bight on Wednesday. The scale and shape of the long wave trough means that a lot of the heaviest of rainfall will be observed in the west through the first half of the week with gales, and mild to warm and windy weather over the southern and southeastern areas of the nation. Rain increases over southern and southeast/eastern areas of the nation with the large system moving into the region from SA Thursday, VIC on Friday and heavy areas of rain develop from Thursday through the weekend over the eastern inland with another trough and cloud band. Further cold fronts develop from the west during the weekend with showery weather likely to continue along the coast from WA through SA and into the southeast. Drier weather for now over much of northern Australia with some light rainfall making it into southern inland QLD from time to time, which may increase over the latter part of next week with scattered thunderstorms possible.

The rainfall focus is certainly over the southeast of the nation in the areas exposed to the westerly wind belt. Noting that the rainfall totals could increase further over the northern tablelands of NSW with moisture surging through the jet stream and stacking up over the GDR which is classic Indian Ocean Dipole weather. Showers over coastal areas could be heavy at times as well. Eastern seaboard could be spared the worst of the rainfall but may be dealing with significant wind issues mid to late next week.

Rainfall over the central and southern interior of QLD and back into the NT is thanks to the Indian Ocean Dipole playing its part and rainfall along the east coast of the tropical QLD coast is thanks to the elevated SSTs over the Coral Sea. The widespread falls over the central and southern interior of QLD could increase if the band of cloud and rain lingers later in the period.

Rainfall is locally heavy tonight with thunderstorms and that will ease tomorrow but further frontal weather is forecast to emerge later this weekend into next week with multiple strong cold fronts to work through and running over the elevated SSTs offshore, modelling will not pick the rainfall potential, so I have added about 20% to what modelling suggests. Rainfall may extend back into the inland with the large-scale system during Monday and Tuesday and possibly once again on Wednesday before conditions ease later next week.

WEATHER ISSUES

Frost Forecast Saturday Morning

Clear skies and light winds under high pressure will contribute to a very cold night developing. Given the dry cold airmass that is in place today throughout the eastern and southeastern inland, the risk of frost is heightened, and severe frost is possible in many areas.

Freeze Forecast Saturday Morning

Freeze conditions possible over the ranges with the risk of conditions lower than -5C possible for a good chunk of the evening causing destruction and damage of sensitive plants and crops plus disruption to domestic water supply.

Severe Weather Watch - Damaging Winds Monday

Damaging winds look to sweep the south of the nation this week with the higher concentration of damaging winds likely to emerge from the west early next week and reaching the central parts of the nation from Tuesday and the southeast Wednesday through Thursday before conditions ease from the west this time next week.

THUNDERSTORM FORECAST

Thunderstorm Forecast Saturday

Thunderstorms are possible along a weakening cold front over the eastern parts of WA and into western SA and a cold airmass following the front may trigger some local hail and squalls about the southern coast of WA.

Thunderstorm Forecast Sunday

A weakening cold front over the southern coastal areas of SA with the chance of elevated thunder with a showery band of rain moving in later in the day with strong and gusty winds possible.

Thunderstorm Forecast Monday

An inland trough over the eastern inland may see a few middle level showers and thunderstorms developing with no severe weather risks at this time. A strong cold front approaching the west of the nation may bring the risk of severe thunderstorms, with destructive wind gusts possible with thunderstorms given the very strong wind fields in place.

Thunderstorm Forecast Tuesday

The strong cold front from WA during Monday whips into the Bight on Tuesday with the risk of strong to gale force winds. Moderate rainfall from any thunderstorms are possible and strong and squally winds.

Thunderstorm Forecast Wednesday

A new rain band forming over the eastern inland with strong wind fields aloft across QLD and NSW may see thunderstorms developing. Storms may be gusty and possibly severe but will check that out early in the week. Another strong cold front approaching the west will bring showers and storms, with damaging wind gusts possible and small hail. A few thunderstorms skirting the SA coast remains in place as a weakening cold front slide southeast.

MEDIUM TERM FORECAST

August 4th-11th 2022

Moisture Watch

Most of the country is caked in moisture with multiple ports of moisture spreading through the north and northeast and spreading west and southwest with this feeding into the jet stream. A strong wave pattern is set to continue over parts of WA, SA and VIC with moisture possibly being pulled in from the Indian Ocea leading to enhanced rainfall chances out west and this then impacting interior parts. The east will see the residual moisture with the lead system clearing from next weekend.

Rainfall Anomalies

Moisture with heavy rainfall and strong winds in the east should begin to clear off from the 4-5th with a seasonal run of rainfall expected to continue over southern Australia with showery weather along frontal weather passing through at pace. A strong cold front approach the SWLD once again through this period with another period of strong onshore winds running over the elevated SSTs leading to above average rainfall chances. Also, the chance of inland rainfall lingering over QLD and the NT.

Temperature Anomalies

A warmer trend will continue over the northern parts of the nation which will filter down ahead of the strong wave action over Southern Australia. The cooler bias setting up over the SWLD is possibly lurching northwards through this period, interacting with the warmer airmass over the nation, leading to strong wind fields and a tighter pressure and thermal gradient, lifting the rates of further inland cloud bands developing.

CLIMATE DRIVERS - SOUTHERN ANNULAR MODE

The negative SAM phase is of interest and may continue into the second week of August, and if that is the case, we could see the more vigorous weather pattern continue through to mid-month for Southern Australia. Rainfall chances for the remainder of the nation would be highly dependent on the moisture spreading through the jet stream on the northern flank of the wavier flow.

DATA - Refer to the video for further information and context.


00Z GFS - Surface Pressure Pattern and Rainfall Distribution - Next 2 Weeks

Refer to the video for further information and context with relation to the fast flow pattern and energetic weather systems moving through.

00Z GFS - Precipitable Water Values - Next 2 Weeks

Not a huge amount of change in the short term related to the moisture spread throughout the country but it is shifting around a little in the medium term and this will see rainfall come and go from one location to another contaminating expectations for the short term. So, review the daily weather video information carefully to understand when rainfall is coming through your location as it is murky in these fast flow patterns.

00Z ICON - Rainfall Accumulation - Next 8 Days

Refer to the video for more context and analysis

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.

More coming up on Saturday morning and make sure you head to the Facebook Page for weather bites throughout the weekend for weather on the fly.


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