European Chase - 12th June 2003
Following the decent convective forecast for Eastern France (>3000j/kg of CAPE, <-7ºC LI, >32ºC surface temps, >21ºC dew points, reasonable 0-6km shear, instability to 150hpa), myself and Nick Verge took the decision to see how feasible it is to chase on the continent from the UK.
I set out at 2300Z on the 11th June after a final check of the models, picking Nick and Steven Verge on the way to Dover for the 0415Z ferry to Calais. Once on board we were able to afford some time to look at the sky and discovered plenty of evidence of middle level instability which I took a few photos of.
By 0600Z the ferry had docked and we were able to start heading S, planning to head for Metz which we expected was about 4 hours away. At Reims we parked up and decided it was time to get a download... first problem, couldn't get a sound internet connection (something to work on for next time!), but thanks to Dave Wiseman (UKww) and Pieter Groenemeijer (ESTOFEX) we were able to updates on the ongoing situation. Whilst parked up at Reims (0900Z) we watched a layer of Ac cas pushing across us and spreading SE. This was probably the cold front, though we weren't sure at the time, so we continued to push on S to try and stay in the hot, moist air.
Next stop was about 100km W of Metz and back ahead of the band of Ac cas by 1100Z (further photos in my album). Here we stopped for quite a while (probably too long) assessing the situation and watching far more convection than we really wanted to see this early in the day. To see the CAPE forecast fully achieved we really needed more CIN to hold things back and keep the heating going. As it was we were recording temperatures of 32ºC and dew points of 22ºC.
MW radio (yes we resorted to that!) indicated plenty of sferics nearby by 1300Z so we took the option to head E towards Metz, where we were met with an interesting Cb base by 1400Z. There was evidence of an inflow tail to a lowered base, but it was right over the city and quickly becoming obscured by rain. Thanks to the volume of traffic and the storms position over the city, we decided that we'd have no chance of keeping up with it. A shame really as the inflow tail suggested this might be a developing supercell, though we were too far away and visibility was too low for us to see any rotation.
With evidence of further storms developing to the SW we decided to push on S towards Nancy... if supercells were going to develop we really wanted to get to the S of them where the inflow would allow us better visibility. About 20km N of Nancy at about 1500Z we decided to stop to take some photos of a very mobile cloud base from the approaching storm. This gave a great view of a hole being punched in the base by the strength of the updraught.
With the storm rapidly approaching and the precipitation shaft now not far away we decided to continue to push S before we got overwhelmed... too late! The hill beside us disappeared and the heavens opened forcing us to pull up... visibility was down to about 400m in this rainfall. Next we start hearing the tell tale bang of large hail on the car... only marble sized at first but soon worked its way up to grape size. By this point I was thinking that the car was going to end up quite pock marked, and we weren't sure if the hail was going to get any bigger yet... thankfully it didn't. We did then get hit by a strong downdraught though which certainly bent the trees over somewhat... probably around a 50knot straight line wind we think, though I didn't stick my anemometer out of the window considering the size of the hail.
As it eased back we headed off S again to try and get in a position to view the structure of the storm... no such luck though. The storms had amalgamated into an amorphous lump with an anvil spreading over the whole area. This was basically killing the chance of any further storms as insolation was cut back in the prime areas. Driving around we saw plenty of hail damage within about a 30km radius where leaves had been stripped from trees... even an occasional branch was down, probably thanks to the downdraught winds. At least I managed to get a photo of the obligatory (though rather pathetic!) mammatus.
We noticed there was still sunshine to the N and considering this was the area of best shear we chose to head NE into Luxembourg, particularly once we caught sight of some rock hard convection to the NE. That's all it became though thanks to the anvil which now must have been spreading over 100km N of the original storms.
We think the potential wasn't really met in the end, thanks to a lack of CIN which allowed things to develop far too early. This then killed off the potential for later in the day when it would've been better had it stayed clear. That said... I got to see the most severe storm I've ever seen, so I've come home satisfied and wanting more!
Lessons learned: make sure the internet connection works; don't chase in Luxembourg or Belgium... the scenery is beautiful, but being in the bottom of a valley doesn't give you enough visibility for storm chasing; although tiring, if the models warrant it, it's easily possible to chase in Europe... between 3 of us it only cost £60 each!
Chase miles completed: 1193
Overall, well worth the trip and something I intend on doing again.
I also managed to capture a few nice shots on the ferry home approaching the white cliffs of Dover...
All content and images © Sam Jowett