Sydney Thunderstorm 13/4/2008
Heavy early morning fog over western Sydney clearing by 8 am. At 10.30 am, I was observing thunderstorm cells sitting over the Blue Mountains.
I have never seen unusual weather like this before in Autumn where fog clears and 3 hours later, thunderstorms start developing on the ranges to the west. This does not give allot of available time for daytime heating for powering thunderstorm cells. Yet, this happened.
I could not take any photos because I had to be in the city to attend the PIA Conference on climate change and urban planning and topics such as thunderstorms will be discussed.
What I noticed about the storm event of 13/4/2008 is that prior to the thunderstorm, large clusters of alt cumulus castellatus clouds pre ceeded the thunderstorm cell.
It appears the storm traversed through Sydney's west early afternoon but did not drop allot of rain. Falls of 5 mm at Blacktown, 6 mm at Penrith occurred.
However, east of Blacktown, it appears the storm intensified. Some rainfall totals were 28 mm at Granville, 23 mm at Turramurra, 28 mm at Sydney Olympic Park, 10 mm at Sydney and 16 mm at Chatswood.
I was in the city and I observed up to 12 cloud to ground lightning strikes including one on a city skyscraper. The storm was very active including significant intra cloud lightning and almost continuous thunder for a period. The storm was pre ceeded by a large lowered shelf cloud travelling NNE and stiff but cold southerly winds and then heavy rain. No hail fell. The storm cell had cleared out to sea by 1.40 pm.
A weaker thunderstorm moved through Sydney's eastern side at 7 pm bringing a further heavy shower but less lightning.
Today I looked at the rainfall figures from it and the heaviest rain occurred within the Cumberland Basin west of the CBD. I am thinking about the behaviour of this storm and my conference that I am attending and I wonder if the urban heat island effect created by the city may have played a role in intensifying the storm or rainfall over the built up area of Sydney.
This is a topic that will be covered in the conference and I will provide a discussion thread on this at a later date.