The often reliable ACCESS-C has been suggesting southern and western parts of our region (as far as SE QLD goes) are favoured for any activity compared to other parts of the region - if any of it does manage to reach the coast in SE QLD (which isn't a certainty yet), it'll probably be later tonight, also reflected in the soundings.

ACCESS-C from 10am today til midnight tonight via Weatherzone - as you can see, it's been pretty close to the mark so far as per usual: https://www.youtube.com/watch?v=...kZU&feature=youtu.be

Edited by user Thursday, 26 September 2019 4:29:45 PM(UTC)  | Reason: Not specified

Love it. A time lapse of ACCESS-C for us all to see. Good stuff.
The resolution and detail of the isobars is pretty impressive.

The sky has darkened here SW and SE of the Tweed. Looking at radar that rain band looks to be heading toward us with some

development. Thats a nice surprise.Very still and eerie here .


Here is tomorrows ACC r. This is the 4pm slot showing the highest precip'signal strength.

The signal starts at 1pm and lasts until tea time . The position is favoring SE QLD tomorrow.

Hopefully some drips at least. For any parched areas


Saturday the precip signal is around Sunshine coast to mid coast latitude.
edit ( There must be some model divergence because ACC r puts that rain signal on saturday further north?)

Sunday and Monday more coastal.


source
http://www.bom.gov.au/au...harts/viewer/index.shtml

Edited by user Thursday, 26 September 2019 6:11:20 PM(UTC)  | Reason: Not specified

Ok. I have had a look at the Lifted index LI for tomorrow afternoon in QLD. There is pretty much nothing there.

So l had a look at the CAPE and it looks like the same as the ACC r model forecast.

So l guess l have a question. Why is LI zilch but CAPE wide spread??

The link
Select 1pm

http://stormcast.com.au/...92703:aus:cape:null:0#sc

The rain signal from GFS bcsh stormcast is weak in the afternoon but much stronger near Brisbane around 7pm

Different model output.

I do have trouble Ken . I really am a beginner here. With storm dynamics. I understand that CAPE gives a better representation of

severe storm potential than LI ?

I did some homework. CAPE means Convective available potential energy.

So the highest CAPE tomorrow afternoon is over the Hinterlands near Murwillumbah way at around 300 joules/kg.

So does that mean severe storms are more likely at 300 j/kg

This is where the soundings come into play. LI,s and Cape are only 2 ingredients. You can have LI’s of -5 and have blue skies. You can have LI’s of -1 and you could have a tornado.

The sounding is a view of the atmosphere, usually, if the balloon makes it which 99% of the time it does, we get to see what is happening way past past 30000 feet. The only problem with a sounding is, for example, it is released at the Brisbane airport so it does not cover a very large area. The sonde attached to the balloon reads all the vital info and then it is analysed and put into the form of the sounding. There we get the temperature, dew points, moisture levels cape,cap,CIN TotalTotals etc.etc
I am still trying to piece that all together and place that into the general weather thread for storms.

So the storm cast for Friday 7:00pm has pretty well fallen flat with the latest run. We could maybe get a shower here and there.

But for Saturday things have picked up a little bit on the positive side for a chance of storms if everything comes together. So I have used the 13:00 (1:00pm) here.

Figure 1 is the LI’s, they are not through the roof as in negative values but that doesn’t really matter, on a good storm day if they ever happen again we will see readings of -5, -6, -7 etc.


Second figure is the cape. Once again not high values in the cape but still there is a chance
Figure 2.


Now the forecast sounding gives us a slice of the atmosphere, but this one is only a forecast sounding, on Saturday we really want to see the Soundings at 11:00. Most of us will look at Brisbane and other areas. Just on a side note, Moree doesn’t seem to have sounding lately, unless I have just been unlucky

Figure 3.



As you can see the LIs are -1.18. The cape is low at 207 j/kg. The cap is very low at 0.2°C. There is some moisture between 825mb and 700 mb.
There is a bit of instability by looking at the grey line. A small inversion at 650 mb but it doesn’t affect the cape or instability. Edit forgot the Total Totals is 52.8 which is isolated possible severe storms. It is close to 53 which is widely scattered possible severe storms. So we “could” see maybe a severe storm if everything pulls together. It is not the hard rule but a guideline with the chart used.
The sheers is good. All we need is small a trigger and they should fire off easily if everything comes together.

So going of this forecast sounding there is a possible chance of a storm around Brisbane and surrounding areas of SEQ tomorrow afternoon. Not over the top, but a possible chance. Some places maybe severe.

This figure of a sounding would have me running like mad. This is a full on storm so you will see the difference. It is called the loaded gun.

Edited by user Friday, 27 September 2019 8:54:28 AM(UTC)  | Reason: Speilinking and proof reading and changing what I wrote, ipad are too small to see everything.

Great stuff Colin! Thank you.
Also wonderful to see that some inland locations had some rain overnight too. Sadly missed out here, but hopefully over the next day or so we will get a sprinkle.

Yes.Thanks for that KEN. Makes sense. If l think back ACC R was only showing very light totals . I forget that models don't show thunderstorm out put and that is why we always say. 'could be higher totals under thunderstorms'
Also forgetting that the tweed is on the other side of the ranges and we sometimes get less with the weaker systems and the ranges get more.


I have seen WATL do very well indeed with some of those big depressions.

Anyway great to have something to watch and cheer for. Good luck today 'guys' with any amount of rain and storms

Edited by user Friday, 27 September 2019 9:14:21 AM(UTC)  | Reason: Not specified