Approaching the whole lot on the back-road to
Trefeglwys....
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The
steering flow was drifting the storm slowly NNW,
and this is its southwestern corner, where a
flanking tower is rapidly developing, feeding
moisture and warmth into the storm.....
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Zoom-in to the floanking tower building. Rapid
convection is underway and the tower walls are
developing a rather smooth appearance....
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Going up! Portait shot to get it all in!
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....to
the north, over the Llandinam windfarm, the edge
of some very heavy rain (or possibly hail) is
visible and thunder boomed out of the
darkness.....
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...zoom back
out: as the convective tower R intensified, its
sides became remarkably smooth....
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....with
marked horizontal striations indicative of
rotating air currents in the updraught - the rain
free area under the cloudbase marks the updraught
base position. It appears that this could have
been a short-lived (say 30 minutes) mesocyclone -
the smooth and striated lower part of the
updraught is certainly what one sees in organised
rotating updraughts.....
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Another zoom-in showing the striated tower now
with lowerings beneath the updraught-base...
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.....quite a
sight! Pity I couldn't get closer - however any
vantage-point is better than none!!
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....tilting
over L a little now, with more lowerings
beneath....
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...zoom-in
under the cloud. Hard to know what's going on
here. The ragged cloud could be a shallow
gust-front due to the torrential rain to the N,
but the silhouetted funnel-shaped structure might
just be one! Not confirmable however...
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....zooming
back out a while later, the rain-free base is
less extensive and the organisation less
obvious...
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....but those
lowerings are still there....
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....as this
zoom shows.
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Here, the
building storm has finally matured. Rain has
started cascading down through the updraught
tower, choking the storm's ability to sustain
itself via this updraught. A new one may begin
and thus sustain the storm for another 30
minutes, but visibility was about to make it
impossible to see whether this would happen....
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....as out
from its flank raced a much larger gust-front.
Gust-fronts typically occur ahead of the rain and
hail. What happens is that cool air dragged down
by the precipitation surges ahead of the storm
and lifts the warm moist air around it. This then
condenses to form long, low, fast-moving
cloud-banks like this, which in severe storms may
be associated with damaging winds...
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...leaving the scene I drove 3 miles west and
stopped again, but the gust-front was hot on my
heels...
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...a little
further west again. Lightning flickered in the
darkness beyond as the storm exploded westwards -
side-on to its overall motion. It was just
expanding wildly...
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...several
miles westward again above Dylife the front is
over Trannon windfarm...
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...while looking N from the top of the pass the
storm's western side can be seen R. Big and mean!
With deteriorating
visibility I gave up on it but returned to the
scene three hours later....
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...its anvil had merged with those of other
storms to form a great canopy over North, Mid and
East Wales...
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...This is under the anvil, looking out S over
Glaslyn and Plynlimon. Storms like this are
awesome things to behold, well-deserving of
respect and admiration.......
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...and a final shot looking SE under this great
canopy, and to further storms over the Borders.
The quiet of evening descends over Llyn Clywedog
- in marked contrast to the violence that has
been going on in the skies through this memorable
day.
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