WINTER 2007-8 part 4: Waterspout off Aberystwyth!

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Although February was a mostly quiet month weatherwise, it began with a stormy start and at 0500 on Monday 4th February I was awoken by a loud rumble of thunder. The forecast had further thundery possibilities so I had a morning drive to the coast and watched as odd bits of rather unphotogenic dark cloud rolled in and gave heavy showers of rain and small hail.

Visibility was not particularly good so I missed a much more intense storm rolling across the Bay, heading straight for Aberystwyth - hi-res Netweather radar for 10.40am below.....


Netweather radar, 1040 radar 4th Feb 2008

With a 70mm/hr+ core it was quite a monster. I was in the Tywyn area and heading south through murk and rain (blue on the radar plot) at the time and it was only when I got to Aberdyfi at about 11.00 that I could see much. The tail-end of the stormcloud was visible and had that hard, dark appearance typical of a strong updraught-base, i.e. interesting -  so I pulled into the car-park alongside the beach at Aberdyfi and got the binoculars on it.....

First funnel over the sea

In no time at all I espied a thin funnel-cloud descending from the cloudbase through the drizzle....

Funnel weakens

These are through a 300mm telephoto hand-held in a gale!

Funnel almost disappears


The funnel then seemed to give up the ghost, but I was still interested in this area of the cloud, and swung the jeep round into a position where I could wedge myself against the door-pillar with the 300mm lens but also get some shelter from the rain.....

Zoomed-out shot of the stormcloud that produced the Aberystwyth waterspout

Pretty much as the naked eye would see it. The lowered area may well be a shallow wall-cloud - an area of low-level rotation within the stormcloud, and where further funnel development would be possible - and that's exactly what happened next!!

Funnel strongly regenerates



This time the funnel grew very rapidly and headed towards ground....

Touchdown!

I guessed it was out over the sea, so would be reported as a waterspout. My vantage point meant that the dunes at Ynyslas blocked the view of its very base, but there was no hope of getting anywhere better - the Dyfi Estuary was in the way for starters!

Funnel on the ground - tornado!


Waterspout getting bigger....

Really quite powerful in appearance now....


Waterspout reaching maturity.....

I think I can see spray in this image being drawn into the vortex, giving it a paler colour....



Weakening slightly....

Here, it is getting thinner from above - a sure sign of weakening....


Just before it lifts off

...and here a sheath of spray mostly conceals the narrow central vortex as it starts to retreat back up....


And the funnel lifts and ropes-out....

This is the "rope-out" stage, and within seconds it had disintegrated and was no more.

My guess was that it was somewhere near Aberystwyth and after emailing a BBC Wales contact this was confirmed - numerous excellent photos were taken as it churned along off Aberystwyth Harbour. Reports that it followed a heavy hailstorm with thunder and lightning are consistent with the visual observations and the radar which showed that heavy shower moving inland from Aberystwyth at the time, weakening as it went (remember that in Winter, warm sea surface temperatures often drive convection, which weakens when a convective storm leaves the sea environment for the land environment)....

Another nice early-season catch then! The rest of February has seen little serious convective activity and the same goes for March - traditionally a quiet month for convective storms, albeit often delivering some strong gales, about which more to come soon!





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