Category Archives: Australian Severe Weather

Australian Severe Weather storms hailstorms and hailstones

Supercell Outbreak Darling Downs and NE NSW 26th December 2017

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Supercell Outbreak Darling Downs and NE NSW 26th December 2017

Models had been excited for about a week with the possibility of a supercell outbreak including some intense supercells across SE Qld and North West Slopes and Plains. The instability was in place together with a likely dryline further west. The convergence of boundaries and this dryline coupled with favourable shear profiles produced ideal conditions for supercells.

The cap held down throughout the afternoon and eventually the storms exploded first in NSW and then in SE Qld. Three isolated supercells developed across the Darling Downs allowing for sufficient space for energy. One particular supercell produced hailstones to 11cm in diameter!

Unfortunately, we made a wrong move and took bad road options although we slavaged a chase with a storm coming to and across the border of NSW to Queensland. This was to be the 3rd supercell in a line from the northern intense supercell. Although it seems a wall cloud was in view in specific phases, it was not sustained and then outflow dominated any attempt to organise. Updrafts can be clearly seen to rotate. Lightning was pretty intense in some of the phases particularly once the storms punched into the upper atmosphere.

Another storm intercepted briefly on the way amongst a break in the rain near Inglewood.


Structured Storms approaches Broke 18th December 2017

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Structured Storms approaches Broke 18th December 2017

Another day of high CAPE - another day of hope. However, there was a cap to overcome. The atmosphere did heat up and it became apparent that moisture was persisting in the Wollemi. With Nick Moir and Rodney accompanying me on the chase, we were joined by John Scerri (although he had to bail out after a short chase).

Storms were slowly developing near Colo Heights initially though struggling. Another cell had initiated near Putty. This soon began to explode and we gave chase: we virtually circumnavigated the cell.

On the northern side, we enjoyed a spectacular anvil and tall updraft. Unfortunately, after it was time-lapsed, the storm began to weaken. And in simultaneous fashion, an updraft, a powerful updraft, exploded into view to it's left. I was confused, wandering how we had gone all the way up the Putty and not even notice this cell. I guess that's what we define - explosive!

It wasn't long before we were en route to Broke. However, we simply had not choice but to stop, film and photograph! This atmospheric accident was not something I had anticipated. The structure was ridiculous! Powerful towers with laminar bands. On radar, the storm had produced a couplet and also veered left of the typical storm directional flow.

The storm transitioned into a couple of updraft and gradually it weakened. More storms developed along the Putty Road and we gave chase, but it seemed most of the energy had been utilised. 

After this, we decided to head home for a meal - long day out! Why not take one last look at lightning! A few shots and I called it quits. I didn't realise that the shot of one bolts was quite spectacular!

Weather 128 radar of the cells in question - we were on the northern most point

See : 128km Radar Loop for Sydney (Terrey Hills), 23:00 17/12/2017 to 23:00 18/12/2017 UTC

Storms Bredbo 17th December 2017

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Storms Bredbo 17th December 2017

Storms Bredbo

Storms Bredbo

It was a tough day - tough decision. Do we chase higher risk of failure stronger cap near Lithgow and surrounds or down south where indications were that if storms did go up thee was better shear environment - supercels perhaps? Canberra bound we were. All on time too. Except - the storms were not on time - they were virtually non-existent!

Storms Bredbo moving east

Storms Bredbo moving east

Second Bredbo storm base

Second Bredbo storm base

Our only option was to head towards Bredbo where a strong cell had organised. It was already entering no roads country by the time we got to it. We headed after the cell towards Cooma that showed inflow base features. The updrafts were eventually disorganising. But alas I noted a string of stratus racing under it! Undercut? I look behind and where we had passed several congestus towers had showed up!
 

Turn around Colin! South easterly winds were streaming and meeting the lighter northeasterly winds further north near Bredbo! The base consolidated quickly as it does in this part of the world with the addition of moisture advection. This did develop into a storm that once again intensified to the east of Bredbo. Some time-lapse of the base provided some rest and observational opportunities.  The storm produced a decent anvil and some interesting structure. Time-lapse did not show any clear or obvious rotation however from our perspective.

This was to be the end of our chase. As we proceeded beyond Lake George, radar indicated a nice storm had developed but alas it did not remain intact for too long.

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