After 8 days of hot weather in the UK a low pressure system slowly moved in from the Atlantic. Ahead of this a warm moist air plume was advected in from France into the South East. Dewpoints were set to reach 20C and CAPE values up to 1200J/Kg (although this was slightly unrealistic 1000J/kg was entirely possible). With deep layer shear in the range of 15-20m/s an MCS was likely to form over Northern France in the early evening and make landfall somewhere on the south coast although location was very difficult to predict due to the sub-model scale of the system. Ahead of this storms were forecast to break out, with a convective temperature of 28C easily obtainable.

The UK Storm Chasers decided to rendezvous in Winchester which was a mid-point between the two events so that split-second decisions could be made on the morning of the chase. Our aim was to chase the pre-frontal storms until the early evening and then ‘fly’ south to the coast to photograph the evening’s MCS.

The first turkey towers attempted to break the cap around 1pm and a clear cumulus field was visible on satellite images stretching from London to Bath in a line about 30 miles south of the M4. At this point we decided to position ourselves at the front edge of this cumulus field to wait for a cell to break the cap.

Using our new 3G wireless internet dongle we were able to continuously monitor the radar whilst sitting on the M4 services near Newbury and observing the now numerous convective cells breaking the cap. At 15:00 the first storm formed and the large CAPE was obvious with the crisp edged updrafts and towers. Heading north, we got ahead of the first cell, which became electrically active only 20 minutes after formation.  Sitting on a hillside we watched it approach with numerous c-c lightning but it was a very non-photogenic storm due to the high humidity making the atmosphere hazy and the intense rain core.

Further intense cells had formed to our west and were also becoming active so the UK Storm Chasers headed down the M4 towards Bristol keeping alongside the Cells as they crossed the motorway on their north-west trajectory. Pulling in just outside Bristol it was obvious the cells we were on were going to cross the Severn Estuary before we could get under their bases. The time was now 5pm (the agreed latest time we would leave this weather event and head south) and deciding that the best was yet to come we made the decision not to enter Wales but head to the coast instead, so we left these thunderstorms to rumble on north-westwards. Just before we left a huge CG came down right in front of us, no more than 2 miles away, spectacularly lighting up the sky – a great ending to our warm-up chase!

Whilst on the journey south, the mood in the car deteriorated rapidly as sferic and radar maps showed the storms we had left intensifying significantly and putting on what must have been a spectacular light show for those in their path. Resisting the temptation to turn around in which would have been a impossible task of catching the storms we kept faith in our meteorology and the forecast and ploughed on south into hazy blue skies. To confound things further the approaching front was not yet electrically active and it appeared we were heading to Sandbanks to observe moderate drizzle (not for the first time!). Thank fully by the time we reached Blandford at around 7pm, radar indicated a lone cell forming just ahead of the front heading approximately towards the New Forest. This then became our target but on reaching the Forest this cell ahead weakened and another formed again to its east. In desperation now that we may miss everything we set Eastbourne as our target, finally catching the cell as it made landfall in Hastings.

We were treated to an unbelievable lightning display as frequent CG’s hit the sea as the storm approached land. As the storm became overhead the lightning and thunder became instantaneous. At one point we heard the thunder before the lightning had even disintegrated. Unfortunately a house had been just down the road and an ambulance and three fire engines soon speeded past us. Hopefully everyone was ok.

This storm now rolled inland and we decided to head further east as the main front which was now very active and making landfall near Folkestone. Treating us to one final light display for over an hour it was a great ending to the day. During the long journey back we checked the forecast for the following day (now the current day) and saw again huge potential for storms in Wales. Reaching home at 3:13am cameras were put on charge and some brief sleep had. See the 29-07-08 chase!