2004 PART 2: 10:05:04
Vigorous convergence-zone convection, East Wales!
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commonly develop in the eastern half of Wales, especially
with a northerly or southerly airflow and slack
low-pressure in late Spring and Summer. What causes them
is a cooling westerly sea-breeze that works its way
inland and forces up the warm air it meets - resulting in
vigorous convection sometimes. The low-level westerly
meeting a higher-level northerly or southerly creates
what is known as wind-shear - when winds at different
altitudes are blowing from different directions. Shear is
important for storm-photography because it encourages the
updraughts that feed storm-clouds to rotate, which in
turn can generate funnel clouds or even tornadoes!
On May 10th 2004, a slack northerly flow, forecast
instability, warm temperatures inland and a sea-breeze
from the word go took my interest and I headed off early
towards the Welsh border.
By mid-morning, lines of towering cumulus clouds
were "bubbling up" near Newtown, as in
this (slightly underexposed) photo. I wanted to
make sure I was with the most vigorous
convection, so I continued into Shropshire....
the Border, looking east into Shropshire revealed
mostly broken cumulus banks....
...while looking back west towards Newtown
already revealed a cumulonimbus storm-cloud. So
that was that. Newtown was the area to be with
today. This was at about 12.30pm, and shortly
after taking this "reference-pic" a
rumble of thunder was heard.
Once in the right area I patrolled up and down
under the storms as they developed. This involved
keeping with a cell until it matured and chucked
out torrential rain, hailstones and lightning,
which I'd then get out of and select the next
developing storm to watch. By now it was obvious
that the whole of East Wales was one big line of
convergence-related thunderstorms. This was
getting exciting, but was about to get even more
Coming back east having
dodged another torrential downpour I first
observed this funnel-cloud at 13.50pm just west
of Glanmule. There was no hope of stopping so I
drove on westwards, through Kerry, and pulled off
the road just west of Kerry to get this image...
...zoomed in here. I then continued west, knowing
as I did that I was only a mile or two from a
brilliant vantage-point, where it was safe to
stop and I'd see this in close-up. The road
climbs a hill out of the Vale of Kerry towards my
destination, and as I went up the hill the funnel
was dead ahead, more or less the same as in these
images. Suddenly it extended downwards, then its
lower third went into the most incredible
convoluted shape, just like the lower part of a
corkscrew! As I pulled over into the
stopping-place it roped-out into a thin thread
that faded from sight as I got out of the car!
It was brilliant to see this but I wish I'd been
able to photograph the corkscrew bit!
Dash-mounted video camera would have been very
useful on this occasion...
I then drove SW along a back-road and stopped at
another good vantage-point, directly overlooking
Newtown. With no precipitation-cores heading my
way for a while I was able to relax and watch
this developing storm. A mature storm is in the
I'd got to the end of one film and was changing
over when a disturbance formed in the cloud-base.
Trying not to panic, I finished loading the new
film and immediately took a wide-angle (28mm)
....before zooming in on it. Although a bit tatty
this was definately not one of the
"scud-funnels" I've seen so often. This
was at 15.00pm.....
...and in seconds it had extended itself
downwards, twisting about visibly, just to prove
to me it wasn't scud! Then, as in the case of the
first funnel, it thinned rapidly and faded from
sight. If only I'd had this quality of view of
the first funnel!
Shortly afterwards all hell broke loose as this
...and although I was just about in sunshine
here, it seemed sensible to drive off the
hill-top in case of lightning, although I had to
grab this pic first! This storm then merged with
others to the north and east: I drove halfway to
Knighton to try and get out of the rain, but by
then it was clear that the most vigorous
convection had ended - getting later in the day
so less solar heat, plus a lot of cooled outflow
from the earlier storms. So it was homeward
bound, and very satisfied!
A pattern was emerging today - if you were going
to see any funnel-clouds it would be as the
developing storms were getting close to maturity
- when the most vigorous updraughts would be
present. Something to remember for the future....
Here is a map
showing the locations of the funnel-clouds. All
were to the N and NW of the numbered
May 11th still looked good too... see part 3!
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