MORNING WEATHER UPDATE - HEAT AND RAIN!

A very warm start to spring for many areas of the nation today. A big upper high parked over the southeast is continuing to strengthen as it moves east today, the upper heights supporting the 30C weather through many inland areas.


The weather is expected to turn sharply colder over the west today with a band of rain sweeping the nation. The rainfall falls apart over SA and then will redevelop over eastern SA into VIC and NSW through QLD and the southern NT. A spring time look with the airmasses clashing over inland areas of the nation.


Lets take a look at the week ahead.

Rainfall for the next 10 days

This is splitting the difference in all the modelling this morning, and as you can see the bias of rainfall is further east for the coming 10 days. Heavy falls over VIC could result in some areas recording a month's worth of rainfall as the front and trough combine with the deeper moisture levels through the east. That rainfall will ease in intensity but sweep through NSW and QLD later in the weekend into next week. Over Central Australia a stalled surface boundary will kick off showers and storms later this week into the weekend, with some areas recording decent rainfall for September, well above average falls likely. The west and south of the nation turns dry from the weekend through next week with the onshore winds in the east keeping the rainfall chances up. How heavy that rainfall becomes still remains to be seen.

Temperature anomalies next week.

This forecast will change later this morning but once again the temperatures will shift from the weekend and a period of cooler weather, but dry weather for much of the nation is anticipated next week.

12z Euro Surface Pressure Pattern for the coming 10 days

The pressure pattern is very similar to the GFS as per the video up until the weekend, once the rainfall moves through with the cold front, the weather turns drier and colder with a strong high coming in to dominate the weather next week. The weather not as cold now on the charts for next week and this will mean my 2 week forecast will be adjusted for next week and the week following showing the more seasonal weather expected under a high pressure system. But again, the forecast confidence is low, when the models diverge like they are in the short term, this is reflective of the uncertainty. The take away is dry weather for the south of the nation with seasonal temperatures into next following the rainfall, the rainfall bias over eastern Australia to continue in onshore winds and the tropics will dry out, potentially the last dry surge of the season.

12z Euro Rainfall for the coming 10 days

Rainfall has not shifted that much in the short term, the rain comes through WA today as expected, then it falls apart with light and patchy falls for SA, then it increases over eastern SA through NSW and VIC as the front runs into the deeper moisture rushing through QLD and NSW from the north, allowing the rain to become more widespread. Then the drier air will surge north through the weekend, pushing the rain through northern and eastern areas of the east and rainfall over the southern and central NT. Next week the Euro differs from GFS and keeps much of the nation dry with cooler southwest winds over the southeast with a few showers and not much rainfall for QLD and NSW.

12z Euro Precipitable Water Values next 10 days

Good agreement on the PW values bypassing SA and peaking ahead and with the front over NSW and VIC through Friday into the weekend before drier air sweeps through the southern and eastern inland with a colder shift. That will send a surge of dry air through the nation, flushing the elevated PW values north leading to a quiet week coming up following the rainfall. The GFS as you can see in the video is opposite in thought, keeping the moisture in play over the north and east of the nation with rainfall chances ongoing. So will have to wait a few more days to see which way the models go. I am leaning with GFS based upon the positive SAM phase.

And the updated SAM forecast keeps the the driver positive this week with members continuing that phase through next week, so the rainfall increasing over the east coast as per the GFS is not too far from the truth if this is correct. The southern parts of the nation could be dry, with weak frontal weather impacting coastal areas, with many areas dry and cool next week. But we will see.

The BoM have issued their forecast of above average rainfall and above average temperatures, we will see. I think the IOD is still a problem at the moment so it is a conditional forecast. At this stage my forecast reflects the bias of rainfall shifting east with the onshore winds and moisture being pulled the warmer SSTs in the Coral Sea.

While some areas such as northwest Victoria and pockets of SA have missed out, others would like the tap turned off, southwest VIC some areas have had probably too much and some areas through NSW. Rainfall means different things to different people. Rainfall at this time of year equals mixed blessings. So will continue to monitor the weather through spring. With less planes flying it means modelling will be week to week and forecast confidence from other forecast agencies I am in contact with, the bottom line is, low confidence forecasting will persist for a while.


I will have another look at the medium term later this morning.