The day was looking pretty
marginal with weak instability and fairly slack mid-upper level shear. The moisture
profile was ok, with adequate moisture from the surface till 600mb and then
mostly dry above that and a cap was expected to hold activity down till a little
later which suited us well!
Skies were clear during the morning, with some small but crisp Cjs developing
on the ranges to our NW and W during the early afternoon. Weak cells developed
around 1.40pm in the Dorrigo region and continued to develop and weaken (pulse
storms) during the afternoon. Nothing substantial had really taken off. Development
was gradually advancing from the SW though, and cells were visible from my home.
A cell that developed on the Border Ranges to my NW was also visible.
By 3.50pm a cell that was heading generally NNE towards the Casino area that
I was keeping my eye on had dramatically weakened on radar. Visually the cell
also looked weak. From this point the radar went down until 4.25pm. This was
frustrating as I didnít notice its re-intensification until the radar came back
briefly at 4.25pm. It was now a solid line of yellow and green and when I went
to get a visual there were two large updrafts pushing through the anvil. It
still didnít look overly strong though. At 4.50pm when a new radar image came
though it was clear the cell was now strengthening, and base features were becoming
visible from my location.
Michael Bath and I decided weíd meet up at Tregeagle. I was out the door immediately
and whilst driving out realised the storm had a guster on it, however this weakened
as I got to the target location and became detached. The cell did have a solid
anvil that was fairly high toped which was nice and it was dropping some CGs.
We watched for a while as a rain free area developed on
its SE side. With precipitation now appearing heavier around the Casino area
we decided to head towards the cell in the hope of getting into to! It also
appeared that the cell was developing on its NW flank.
We stopped about 14km N of Coraki to quickly have a look
at what was going on. The rain ahead of us had now weakened, however towards
the NW the precipitation was looking quite intense. After admiring the lovely
thick anvil we headed of towards Kyogle on the Lismore-Kyogle road.
Several nice CGs were observed on the trip out, and it was obvious that a guster
was developing on the now severe cell. We stopped at the turnoff to Casino however,
as the cell had gotten away on us! We stayed for a little bit to enjoy the lightning
from the cell before anvil rain enticed us to head back home. On the way back
I stopped briefly to photograph what appeared to be the large guster on the
cell. It was disappointing it hadnít done this S of Casino!
Just outside of Goonellabah on the trip home I spotted
some mammatus from the Kyogle cell out of the corner of my eye and quickly pulled
over. The storm had a lovely backsheared anvil with mammatus that was brilliantly
illuminated by the lowered sun. I took a few photos before racing back home
to photograph it as the sun set. A perfect way to end the chase!
The storm weakened as it crossed into Queensland, however
some lightning was observed at dusk. The storm had caused some damage when it
hit Kyogle, blowing out some windows at a home and knocking an old church building
off its foundations!
Grafton local scale loop 0230z to 0750z 12/11/2003 (1.30pm to 6.50pm local)
Grafton medium scale loop 0230z to 0900z 12/11/2003 (1.30pm to 8pm local)
03z to 10z animation
AVN Model Analysis
From NOAA 12/11/2003 06z analysis run
Humdity 850 hPa
Humdity 700 hPa
Humdity 600 hPa
Humdity 500 hPa
Humdity 300 hPa
(C) 850 hPa
(C) 700 hPa
(C) 500 hPa
(C) 300 hPa
(knots) 925 hPa
(knots) 850 hPa
(knots) 700 hPa
(knots) 600 hPa
(knots) 500 hPa
(knots) 300 hPa
Report compiled by Dave Ellem and Michael Bath