2011 was not a good year for thunderstorms in Canterbury! To be honest it hasn't really been that good in a while apart from a reprieve in 2009. Oh the pain, had to go after anything that looked possible. Would you believe Christmas Day was the only good day in 2011, why did it have to be Christmas Day! I couldn't just abandon the family could I? I didn't this time, but who knows in future if it looks good enough. Those storms on xmas day happened mainly down towards Fairlie as a result of surface heating and moisture creating an unstable atmosphere, also good surface convergence on the foothills down there. I'll include two photos at the end of this report showing the cumulonimbus clouds as they started to fire taken from me back up in Christchurch looking over the back fence!
So back to this day in November, as I said we went after anything and this storm wasn't great at all really. Saw one lightning strike and heard one lot of thunder, that was it and I got the only bolt on video. Hooray! not..... The upper air (500mb) was cold at around -25 to -26 °C. Surface conditions were not very favourable being northwesterly and drying it out, however sometimes you will get storms just on the coast south of Banks Peninsula as fronts move up from the southwest in these conditions. This is what I was counting on as a southwesterly wind change was moving up, the best timing going by the models was just after 6pm so Steve and me set up at the Selwyn River mouth of all places around then and watched a dark cloud brew.
Metservice MSLP maps: 0000z 0600z
And here are the storms that appeared on Christmas Day with associated MSLP maps. A bit odd happening in the middle of an anticyclone but it can happen if conditions suit.