NATIONAL WRAP - THE COLD BLAST COMES NEXT TO THE SOUTH AND EAST - THE WEST AND NORTH DRY AND STABLE.

The rain band over the eastern inland of NSW and extreme southern QLD is moving east, propelled along by a long wave to the south of the nation. Light falls for the most part and a few thunderstorms this evening could bring about some moderate falls.


The next front is due to approach during tomorrow over the southeast with gusty winds developing. This front will be followed by a strong surge of cold air, that will likely rise through eastern SA, VIC, TAS, NSW and southern QLD early next week with farmers and graziers issues expected.


Over the north warm to hot and dry with potentially below average temperatures on the way mid to late week. The west turns hot and dry with very warm weather for the west coast.


Rainfall Next 10 Days

Not much expected in the coming 10 days, the bulk of it through the southeast on Monday with a strong cold front then turning sharply colder and drier, high pressure coming in and suppressing rainfall chances. So this is a time where many can prepare for when the tap is turned on, and for some it could be turned on full blast in the end of the month.

Moisture Watch - September 24-October 1 2021

This is the period where moisture will finally return across the nation, as the strong westerly winds through the next 4-5 days finally retreat south, high pressure begins to move southeast and east through nation, sending an easterly flow over northern Australia. Thsi will drag moisture over the tropics, with increasing rainfall chances. The mid latitude westerly wind profile will see moisture surge from the Indian Ocean (refer to the Indian Ocean Update for more from earlier this week) - this feeding troughs that develop out of high heat through Central and Western Australia. A positive SAM phase is also growing as an outcome for the Southern Ocean meaning that easterly winds may freshen for QLD and NSW as we track into the latter part of this month and into early October.

Rainfall Anomalies This Week - September 18-25th 2021

Not surprises, quiet week, marginally drier values than normal for this time of year over much of the south and east, though seasonal values for much of the north and west, with this time of year usually dry and stable for longer periods of time.

Rainfall Anomalies Next Week - September 26th-October 2nd

This is where will see rainfall chances increase sharply for inland WA through SA as moisture is drawn in via the jet stream into troughs, creating inland rainfall chances to increase and the weather over northern Australia to return to to build up conditions. The weather to remain in build up from this point. Still a few areas of below average rainfall to iron out over the course of early October, I fully expect the weather to turn wet for October over NSW and QLD with easterly winds redeveloping.

Temperature Anomalies This Week - September 18-25th 2021

The sharp cold snap is expected to sweep north with a chance of frost developing over inland areas mid week. Also issues for graziers in the east, after this mild spell, the weather is expected to turn well below average, thus putting stock in the areas on blue and below in some stress. So farmers and graziers be aware.

Farmers and Graziers Monday through Wednesday

A colder blast moving through on Monday over the southeast will extend into NSW on Monday night through Tuesday. Low level snow is also possible through this event with gusty winds and high wind chill with frequent showers along the GDR and over the southern inland. Showers turning to areas of rain over southern VIC with scattered hail and thunder Monday through Tuesday. Snow also down to low levels. Showers over the southeast of SA more isolated back over the remainder of the Ag areas with the chance of hail about. Strong southwest winds will ease later Monday and conditions moderate Tuesday afternoon. Frost will follow this spell of precipitation for SA on Tuesday morning and the eastern inland Wednesday and Thursday with severe frosts possible. Charts to follow on Sunday, just waiting to see the thermal values tomorrow before I finish that work.

Temperature Anomalies Next Week - September 26-October 2nd 2021

Temperatures will be warm over the west this week coming and that air will be transported eastwards with a northwest flow aloft, increasing day time temperatures above average. Humidity and increasing cloud cover over parts of the tropics may moderate temperatures in pockets. The pattern flips in the west with below average temperatures developing thanks to a long wave and southwest flow parked through the region, but this carries lower confidence.


DATA

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

The frontal weather comes through this weekend into early next week, then it is dry and cold for much of the nation through this coming week, with no rainfall for the best part of 7 days. Dry for while. The pattern is still expected to shift from about the 24/25th with moisture returning from the Indian Ocean and also some chance of moisture returning via easterly winds (the positive SAM phase still a real chance of occurring and flipping the winds into the east). The rainfall may make it into SA, VIC, NSW and QLD by the last 3 days of the month, some chance too that decent falls for areas that have missed out is a solution on the table at this time.

GFS 00Z - Precipitable Water Anomalies- Next 2 Weeks

Lots of brown and red shading on the board, not what you want to see if you are wanting rainfall, it is what you want to see if you are needing a dry week. The pattern remaining largely unchanged until later this week into the weekend, when moisture returns to the west of the nation and begins to filter throughout for the last week of September and persists at this stage into early October, with some decent anomalies coming into SA through the southeast and east supportive of widespread rainfall and cloud cover.

Simulated Satellite into the medium term - Total Cloud Cover - September 29th 2021.

Saturday 2nd of October 2021.

GFS 00Z - Rainfall for the next 2 weeks - Most to fall in the last week of September into early October.

GFS - Rainfall Anomalies - Next 2 weeks.

The green streaks are associated with rainfall coming back later in the period, so the dry spell is still expected for the coming 7-10 days for much of the east and north. The dry weather over QLD will be overridden at some point through this period.

00z Euro - Surface Pressure Pattern - Next 10 days

This is supporting the dry air surging throughout the nation and suppressing rainfall chances for inland areas of the nation for the coming 7 days with high confidence, the rainfall and cold weather over the southeast carries a high confidence. The weather over the north returns to dry season conditions, perhaps the last long stretch of dry season this year. The weather turning unsettled over WA later in the run with a deepening trough and moisture return.

00z Euro - Precipitable Water Anomalies - Next 10 days

The moisture is on by with a dry surge to sweep it out Monday through the end of next week, a nice pop of dry cold air coming through the central and northern inland areas of the nation. The moisture takes about a week to return from WA with that being the next opportunity for rainfall in the outlook with a cloud band developing.

Euro 00z - Rainfall next 10 days

Rainfall after it clears the northern inland of NSW overnight, is strictly coastal and I suspect a dry week for many away from the southern coastline and southeast. Showers may return later next week to north QLD and over the SWLD in the day 8-10 window. Otherwise, I hope you like the sunshine for much of the nation.

Euro 00z - Rainfall next 15 days

The Ensemble data also supports rainfall coming back end of the month and into October with moisture surging through the nation and being picked up by a slow moving trough and or complex low. The frontal weather looks to retreat southwards for the end of the month in line with the SAM trending positive.

00z Euro Rainfall Anomalies - Next 2 Weeks.

Similar to the GFS with the rainfall coming through from west to east across the nation, but I do caution you that numbers over the east may change if the SAM turns positive, something models have been playing with, that is not the case tonight.

More weather coming your way on Sunday morning. Have a great evening.


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