Michael Thompson's Australian
Storm Chase Diary
Thunder Downunder 2005 - Day 3, 27th November 2005
Narrabri, NSW to Maryborough,
QLD
All photos clickable
for larger size
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This
picture shows the massive scale of the storms that developed near
and east of Toowoomba. The contrast between the brilliant white
anvils and sunshine made for tricky photographic exposures, therefore
the pictures needed some levels adjustments - local fly also decides
to make a guest appearance.
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Looking
180' from the last photo. This flanking line feeds into a severe
storm, note the separation of an anvil collar at top of storm.
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The day two check
in to our motel at Narrabri was 11pm, we were all very tied from the lightning
show. Our dinner that night was at Coonabarabran where the highlight (
besides the odd rumble of thunder ) was the heckling the unfortunate local
pub band was receiving from their grand audience of five.
There was no need
for alarm clocks today, all four chasers were woken at once from a loud
bang of thunder at 5.30am. Looking outside and the the mid levels were
racing away to the NE - a sign that would set the pace for the rest of
the day.
We left Narrabri with
a NW wind, a trough line racing NE and lowering dew points. We passed
through Moree and Goondiwindi, stopping at Inglewood in the Queensland
Darling Downs to assess the situation. Convection was occurring, but so
much junk it was hard to pick anything in the sky. The NW wind had picked
up to around 20 knots, dew points were barely adequate, but under increasing
threat. After 30 minutes or so a small storm formed north and we raced
towards it. It was this initial storm that gave us a second taste of the
shear we would deal with. What at first appeared an easy intercept was
missed, with the storm passing east of us quickly. We estimated the storm
speed at least 50-60knots. Running down a storm from behind on Australian
roads was not going to be an option today.
Near Pittsworth the
storms began to organise better. The eastern sky was dominated by three
massive storms, with a line of developing storms stretching NW aligned
to the trough, which was speeding its way to a tropical vocation.
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Looking
up at the updraft of one of the storms, note the collar!
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Another
of the strong storms - possible supercells, as shear was more than
adequate. ( Powerlines removed )
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We spent the rest
of the day chasing the trough line down. At one stage a large storm developed
on the end of the line that produced an anvil overhang that was perhaps
two to three thousand metres thick. I have never seen anything like it.
As the anvil spread it was trained down the trough line of storms. The
animated satellite picture shows this strange blob progressing quickly
SE along the line - it must have been a mystery for anybody who saw the
satellite pictures without an explanation.
We finally gained
the storms just near Kilkivan, near the aptly named Devil's Mountain.
We experienced flash flooding rain and a barrage of lightning, including
two strikes less than 50 metres from our cars. During a lull in the rain
and just on sunset, the storm base to the east took on the most unearthly
shade of blue I have ever witnessed. It was a glowing cobalt blue, to
all four chasers it could only mean we had just outflanked what we suspected
was a very severe storm. ( Reports of cricket ball hail in news next day
). We ended day three at Maryborough with clearing skies and dropping
temperatures.

The post
analysis of the wind shear shows some interesting figures - bear in mind
this is GFS analysis, real conditions may have been slightly different.
Surface
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*NE
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10-15
knots
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900mb
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SW
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30
knots
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750mb
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WSW
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35
knots
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600mb
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WSW
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50
knots
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500mb
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W
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50
- 55 knots
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300mb
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W(
slight NW )
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60
knots
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200mb
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NW
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70-80
knots
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The surface winds
we had were NW at 20 knots, but we were outside the storms, which I am
99% sure would have been in NE winds on and ahead of the trough. So what
is unusual, well the shear has a veering pattern, most common in the northern
hemisphere. The shear however accounts for the movement of the line of
storms we observed perfectly. It also leaves room for possible supercell
storms.
  
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