FRIDAY MORNING WEATHER - STORMY CHANGE OVER THE SOUTHEAST. MORE ON THE NEXT WEATHER MAKERS!

The weather has been very active over the past week with low pressure troughs and frontal weather combined the deep moisture content throughout the atmosphere spanning thousands of square km, leading to widespread rain and thunderstorms with bumper rainfall totals.


The last in the sequence of active weather is forecast to approach the southeast states today and will also act to clear out the high humidity and bring about more seasonal weather, with overnights falling away and daytimes dropping to near normal thresholds for many of you over the south and southeast.


A band of rain and thunderstorms will develop for eastern and southern SA this morning before amplifying as it heads into Victoria and NSW with some chance of severe weather, with heavy rainfall leading to flash flooding. The bulk of the rainfall should infact clear through to the east of Victoria by Saturday and be focussed over southern and eastern NSW on Saturday before clearing north and east by Sunday.


The system is moving faster than previously modelled but will still bring areas of heavy rainfall to VIC and NSW, possibly the ACT, but the activity looks to be north of there.


Now as we move into the early part of next week, much of us will be dry, cooler and the nights colder. The day time weather lovely, from the west through southern Australia and for much of the southeast and east. Just a few showers expected in onshore winds over the QLD coast and through northern areas in the humid airmass (upper ridge will suppress a lot of the rainfall potential there).


The next weather makers to watch are the frontal system over Southern Australia and whether that front propels a pool of cold air that can form a broad upper low later next week and the other weather maker is the developing plume of moisture over the tropics and whether that can be drawn south into QLD ahead of the dry surge later next week bringing up rainfall chances for the northern and eastern parts of the nation.


Lets take a look

FORECAST

Rainfall Next 14 Days

Rainfall is forecast to move from SA through into VIC and NSW and become more widespread and heavy today as a cold front slams through moist and warm air left over by the previous rainfall event. The front itself will act as a sweeping brush and kick out the humidity once a westerly change moves through the southeast and drier weather will follow the rainfall so once you get into cooler drier air from tomorrow night through the weekend, your rainfall chances fall away. Weather generally across the nation from Sunday is much drier away from the northeast of NSW and southeast QLD where showers and thunder will continue and across the northern tropics where showers and thunder will also be appearing. The weather turns interesting next week. The next rain maker on the horizon looks to still be mid next week for southern parts of the country with the region from Ceduna to Eden and extending into Central NSW being the area of interest. The other rain maker to watch is over northern Australia, whether we see deep tropical moisture moving south into the jet stream which will feed an upper trough remains to be seen, but heavy rainfall has been appearing for much of the NT, QLD and NSW from late next week into the weekend as well. The west, seasonal conditions with drier weather for much of the period which is normal, but a front could approach later next week with some rain. Into the medium term it will be watching that rainfall over northern Australia and whether that can move south or not.

SHORT TERM CLIMATE DRIVERS

SOUTHERN ANNULAR MODE - TENDING POSITIVE NEXT WEEK

This will see the westerly wind belt settle down and allow easterly winds to return. Impacts to watch will be on the southeast with the frontal boundary next week, will that turn into a low pressure system. Other impact, rain and thunderstorms developing over the far north of the country spreading into QLD.

THUNDERSTORM FORECAST

Thunderstorm Forecast Friday

The front and trough from the Bight will add supportive wind fields and atmospheric dynamics to produce scattered storms over a wide area of the east with moisture lingering from the current event being lifted by a wave of unstable weather moving east. A dry line may establish through the inland and could be the focus of strong storms with damaging winds and heavy rainfall leading to flash flooding


Thunderstorm Forecast Saturday

A dry line will continue to move through the interior of the country with a band of rain and thunderstorms moving north and east through the eastern inland. Storms could be severe if there is sufficient surface based instability but most storms should be elevated and gusty with moderate to heavy rainfall possible. Storms will continue over the northern tropics mainly during the afternoon and evening.

Thunderstorm Forecast Sunday

Thunderstorms should retreat back to the northern tropics but even here, the coverage is above average for this time of year leading to above average rainfall chances. Ridging keeping the rest of the nation settled.

Thunderstorm Forecast Monday

Thunderstorms are generally likely over the far northern tropics with the risk of some of these producing gusty winds. Thunderstorms are also possible over the southeast inland of QLD and northeast inland of NSW with a weak trough nearby.

Thunderstorm Forecast Tuesday

Thunderstorms are still possible over the northeast of NSW and southeast QLD with a weak trough and thunderstorms may continue to expand once again over the tropics in advance of a tropical wave. Mostly settled conditions elsewhere with ridging and sinking air motion.

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.


12Z Euro Surface Pressure Pattern and Rainfall Distribution - Next 10 Days

The surface pressure pattern is fairly dynamic today but once we lose the front and the collapsing trough over the eastern parts of the country late Saturday, conditions are forecast to settle down with a firm ridge sitting over much of the south and a zonal flow to the south of this ridge bringing showery westerly winds to Tasmania (but a sign that the colder air is not too far away) and over the humid and unsettled weather will continue with scattered showers and storms with more above average rainfall chances. The next system over the southeast is from mid next week, once again keeping a close eye on that system as it has taken on many different looks and while it is looking less likely to form into a low pressure system over the southeast, it could propel very cold air and deliver the first frosts to the south and southeast. In the west, things quite, warmer and dry so plenty of a chance to get onto the sowing season with pace this week. The next rainfall events are forecast to appear over northern and northeast parts of the nation next weekend.

12z Euro Precipitable Water Anomalies - Next 10 Days

The humid and unsettled weather over the east of the past week is on the way out with a drier and cooler airmass moving through. The humid air being pushed back to the northern parts of the country by early next week. The next change rolling up from the south during mid next week could lead to showery weather over VIC, SA and southern NSW with snowfalls coming back to Tasmania as well and a drier airmass to move northwards. The moisture in advance of the dry surging north later next week over the NT and QLD could be lifted into a rain band bringing more above average rainfall from next weekend.

12z Euro Rainfall Accumulation - Next 10 days

Refer to video for more information

12z GFS Rainfall Accumulation - Next 10 days

Refer to video for more information

12z CMC Rainfall Accumulation - Next 10 days

Refer to video for more information

12z Euro Rainfall Accumulation - Next 15 days

Refer to video for more information

12z GFS Rainfall Accumulation - Next 16 days

Refer to video for more information