Passing storm - pseudo tornado - 17th March 2012
#1 Guest_Chris Lloyd_*
Posted 17 March 2012 - 18:37
This was passing up the severn valley. Had a lot of hail today. Loads of scud associated with this storm, lowering of cloud where the sun was.
#3 Guest_Chris Lloyd_*
Posted 18 March 2012 - 11:54
Difficult to tell really - it was quite a way away. I was interested just as much in the area where the sun was. A triangular lowering came down and then went back up again. The camera over-exposed it so not so easy to see on the vid.
Enjoyed watching it anyway, even if it was just scud. Plenty of hail around yesterday, so plenty of convection about.
Posted 18 March 2012 - 12:50
Had a look at the video.
It is definitely NOT a tornado, but the end elevation view of a small gust front.
What you have here is the cloud forming on the leading edge of a downdraft. What is happening, is that a shower on the left of the photo/video has generated a downdraft of cold air, the nose of which is moving from left to right across the field of view. Bearing in mind, that many of your showers, (along with those in other areas) contained hail, the downdraft was significantly colder than the surrounding air.
Thus the nose of the downdraft would have been efficient at scooping up milder and moister air, this air rising to produce the finger of cloud seen. If you look closely, one can see cloud rising along the right hand edge of the finger, but there is definitely no rotation.
Finger effect may have also been augmented by the downdraft being funnelled up a valley.
As an asside, temperature falls of 5 to 7 degrees were recorded in the hail showers across Devon during yesterday afternoon, very typical of Spring showers in cold air, where the sunshine is strong enough to raise temperatures significantly between the showers.