Hi, for those interested, I have updated my waterspout entry with a radar image of the thunderstorm producing the waterspout.
Here is a series of radar images of the squall line that affected the island on 30 April, which our Finnish forecaster was referring to (see my earlier post on 20 May).
The gust front is quite distinct.
We had an unusually large number of squall lines on consecutive days this April. April is the transition period between our two monsoons (northeast monsoon and southwest monsoon). We normally get the squall lines during the southwest monsoon period, but we can also get them at other times of the year, whenever our winds change to westerlies/southwesterlies.
I must apologise for the quality of the radar images - they've been showing a lot of noise/interference. I think we should consider upgrading our radar soon, it's getting on in age ...