Australian Severe Weather Forum

Again more storms are forecast in a rather hot and humid weekend ahead, what will bring on Friday, Saturday, Sunday and Monday? Who knows, but all I know is if we don't get more moisture things look marginal so it will be rather frustrating, so let's discuss this storm potential!

Hi Steven,

I'm going to have a more detailed look at things late tonight when I get home and will post some thoughts on here.  Interesting to note that the DP's around SEQ have been pretty low today with some fairly warm temperatures.  However, in the last 30 minutes, I think the SE'ly change has finally made it to Brisbane as I can now see low level Cu moving relatively rapidly inland (from the SE).  I'm hoping this change can push 100-150km inland over night tonight (might be a bit hopeful but we'll see) as this would inject a nice burst a moisture onto the ranges for tomorrow. 

More thoughts later.

Macca

There is good low level moisture over the region this morning thanks to the weak southerly change yesterday afternoon. Winds are northerly here with the dewpoint sitting on 15.

Last night's Brisbane sounding shows quite a strong 850 hPa inversion, and another at about 550 hPa. Will be interesting to see how this changes during today.

Hi all,

In response to the two points Michael raised, I think the 550mb inversion will weaken as the upper trough approaches this afternoon and the 850mb inversion - i hope this hangs around as it would keep convection nice and isolated with any luck.  But on that, you'd then need to look for areas where this inversion (cap) can be broken - the ranges and along the trough. 

Today has looked better with each model run. Not sure if anyone has noticed (maybe its just me) but the models have really not been that great in forecasting the last few events until the morning of the event. Makes it tough to make a proper forecast target a few days/the night before.

Shear isn't great in the 600-500mb layer today based on forecast soundings but the latest LAPS run shows a great upper trough pushing into SEQ today. Upper troughs always make me happy  . Apart from the 600-500mb layer, shear is pretty nice. The lowest 1-1.5km are generally N to NE in the 10-15knt range and then westerly above that, getting up to 25knts at 700mb. Shear at the anvil level is around 50knts which isn't too bad either. Instability...well with the upper trough pushing in and dropping 500mb temps down to -14 to -16C range (-14C over Wide Bay and -16C over the BR's), combined with say 30/15 gives some pretty tasty instability indicies with CAPE approaching 1600j/kg and LI's in the -7C range. Certainly nothing to shy away from. (Not totally dissimilar set up to Nov 8 last year).

Without going into too much detail, I think I'd probably head out to somewhere like Marburg. My preferred are of choice is probably around Yarraman - Nanango (maybe a bit further N) but to keep the southern option open, Marburg is a good starting point as you can shoot S to Boonah if things fire down in that region.

Looks quite unstable for the next few days too but again its hard to pick a target as the models don't appear to have a decisive handle on the situation. Mid/upper level moisture may come in to play over the weekend.

Macca

Ok - three words...VERY NICE SOUNDING.

Great cap - breakable - but strong enough to keep convection isolated. Shear is lacking as has been mentioned but there will be some very nice storms out there later this afternoon (wouldn't expect much before 3pm). Sat pic is nice - shows where the moisture is at the moment.

I think I've seen enough now to commit to N of the Warrego Hwy. I reckon you can squeeze another 1C (possibly 2C) of moisture by being further N but the upper level temps and shear are largely indifferent. What does this mean? Simply more instability. I'm not discounting the southern option (ie BR's) - I think that area will see a storm or two and the area is actually more favourable for chasing. But if I was chasing today, I'd be trying to find the biggest, nastiest storm I could find which I think will be over the Brisbane Valley area.

With the shear being somewhat slack, I wouldn't expect anything to make it to the coast until quite late (6pm).

Fun times for those chasing today!! Enjoy!

Macca

PS: Watch out for your windscreens today folks!!! 

Gee looks quite nice. I like the quite sharp drop-off in temperature with height through the mid-levels, and also the drying above the boundary layer airmass. IMO, it's a borderline situation for an HP today since although the deep layer shear is somewhat weak, the surface to 850 flow veers nicely in the early evening......and updrafts should be quite strong. Suppose this will be dependent on if/how early things fire up and, thereafter, the extent to which cold pooling courtesy of the weak mid-level flow facilitates more widespread stuff.

I could sense that humidity just pour in last night, although hovering at 21C it was rather uncomfortable to sleep, I do have a good feeling about this one, largely because of the soundings, but I don't have expert knowledge what will happen ahead but by going by instinct I can almost feel large hail is coming. With dew points at around 15 development is likely late, however interestingly at my location it's at 19.

I long for that kind of air to invade us down here!

Little cell has developed NW of Mt Perry and is stationary. Some strikes recorded.

Good luck all.  From reading the posts the sounding surely is sweet.  21c overnight would be nice at the moment here, it's 26!  Look forward to seeing the posts and pics.

Mike

Arrrggg!! nothing whatsoever tonight, it has mainly been confined to the Capracornia region and tomorrow doesn't look like storms are likely either, I am not to sure what Sunday will bring but Sunday and Monday are our best chances at this stage.

Looks reasonable for storms in the coastal regions between about the Tweed and up today. The air here has a lot more moisture in it than yesterday, with the DP around 17 and a NNE breeze atm.  The shear profile is very good near the coast. We have an upper trough but the mid level lapse rate does not appear to be as nice as Friday in the GFS forecast.

The surface temp and dew point were not sufficient to get through the cap yesterday - which was pretty strong yesterday:

Brisbane Friday 05/10/2007 00z

I also thought there was too much dry air above 870 hPa, but welcome feedback about that.

MB

The latest Bris sounding is very nice so long as the cap can break. There's a LOT of instability above 900 hPa

Brisbane Saturday 06/10/2007 00z

Bit of activity inland NSW right now - hopefully someone can report more about those later.

MB

Hi guys,
Temps are up today, currently 34º and it's fairly humid, I apologise I cant give you exact numbers as our local "weather station" or "thermometer box and tin can with a ruler in it" leaves something to be desired to say the least lol? I surely need to invest in a good barometer set-up asap! We have a covering of what seems to be high, wide spread cirro-cumulus that seems visible on the latest sat pics so I would imagine the temps may increase once it has passed and might reach 36 or 37º.
A few small cells have passed through the Broken Hill area and looks like some activity around Orange. So it'll be interesting to see how the afternoon progresses? Best of luck to all that are willing to chase today!

Regards,
Shauno   

things looked good somewhere lol i got these snaps from coolangatta( on top of the big hill near the beach looking towards the airport)

Hi all,

Saturday 6th October 2007

Had a nice storm chase on my way up to Bryan's 21st.

Started off with a slow moving cell that formed southwest of Casino and tracked slightly south of east. This had great updrafts but was not very high topped until later when it got close to the coast. It was pretty obvious it was very dry west of this activity, with the only other area of interest on the Border Ranges.

This was my target anyway, so headed to Kyogle then the Lions Road over the Border Ranges. The timing turned out very nice as the main storm of the day was now developing.

(click images for larger view)

3.25

3.37

By the time I had reached the NSW/QLD border the storm had really taken off. The updrafts were exploding virtually overhead. The base was quite high and was not producing much precipitation (that I could see). Thunder was booming in the valley though I didn't see any lightning.

3.54

4.02

I watched development here for 10 mins or so before heading towards Rathdowney. The hills get in the way a bit, but not for long.

I was amazed at the power of the main updraft - it sure tapped into all that CAPE !

4.09

4.12

4.14

It took on a bit of a corkscrew appearance briefly but the whole storm weakened soon after this.

4.29


Back at home the webcams sure got a show too !   Well worthwhile downloading these AVIs

http://australiasevereweather.com/video/timelapse/2007/1006-01.avi

http://australiasevereweather.com/video/timelapse/2007/1006-02.avi

regards, Michael