Saturday, July 16, 2005

Thunderstorm Outlook Sat-Mon 16-18 July

Tonight there will be a chance of thunderstorms from central France into the Alpine region. Near the Alps, conditions seem favourable for more widespread storms, with some chance of a mesoscale convective system (MCS), but in terms of synoptic scale forcing things look somewhat marginal.

On Sunday, a thermal low will develop over western-central France, and diverse models forecast convective (thunderstorm) precipitation in that area... so it seems likely that widespread thunderstorms, maybe a MCS, may form.

Finally, the best and most classical setup for sprite-generating MCS storm systems appears to happen Monday evening/night, as a cold front pushes the warm airmass eastward over (south)eastern France and the Alpine region.

After that, there will be a lull in storm activity for several days - perhaps a week - due to the build-up of high pressure over the eastern Atlantic Ocean.

Wednesday, July 13, 2005

Thunderstorm Outlook: Friday-Monday 15-18 July

Will we have good stormy conditions at the onset of this year's EuroSprite campaign? Let's have a look at the various numerical weather forecasting models. The current scenario that most models agree with, is that an old upper trough very slowly approaches the European continent these days. By Friday, the ridge of high pressure over the UK and Benelux has eroded and a thermal trough will expand northward from Spain, with warmer and moister air flowing into France.
This could lead to the first thunderstorms over France on Friday, and since the scenario progresses slowly, a repeat on Saturday is possible. This is especially true in ECMWF and GFS, but some models such as UKMO and NMM think of more westerly upper winds that let the thundery conditions slip eastwards out of France to northern Italy and southern Germany, followed by cooler air over France.
The ECMWF/GFS solutions feature Sunday as another thunderstorm day over France. GFS keeps the thundery conditions the longest, even on Monday, but my feeling is it may be too good to be true. I will keep you updated on this later this week. At least it seems that the Danish team will have reasonable chance of having some natural flashes available to test the camera... :)

Tuesday, July 12, 2005

Low-light sprite cameras to be installed this week

The Danish team will be undertaking an end-to-end test of the OMP-Pic du Midi system tonight and make the final modifications, if needed. The Puy de Dôme system is the same as the one that was used in 2003 (that captured more than 100 sprites) so it should be running soon.

One of the black-and-white images of a sprite captured by the low-light camera on Pic du Midi in August 2003. The large sprites in this image are termed "carrot" sprites, the smaller ones "columniform" sprites.

Olivier Chanrion and the Danes will take the instruments to France by car, starting Thursday morning, so during the weekend they plan to have the OMP-system running and after that the Puy de Dôme-system. During the first week, the software will continue to be modified and streamlined, making the commanding of the systems as easy as possible. Then, it is a matter of having favourable conditions to observe sprites!