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Interesting weather afternoon!! Shortly after 1930z (3:30 pm EDT) I noticed what looked like mamatus clouds to the W and SE of my location in W London, Ontario. Grabbed the camera and started shooting.
First batch had to have White Balance post-processed in CS3 (to match what I was seeing as best I could), as I had shot a concert with the 50D the previous night and had both the WB and Exposure Compensation set accordingly and not changed them at the end of the night! These were all shot with the ultra-wide Tokina 11-16 mm. Looking SSW:
Set the in-camera WB settings for current conditions…
It was reasonable to assume that the mammatus were associated with convective activity, and a look at the Detroit NEXRAD reflectivity confirmed the assumption. The red dot approximates my location.
Switched over to the 18-55 – looking SSW:
Looking SW:
It was fascinating to see the mammatus expand in size, and in some cases appear to have virga under some of them – at which point I would no longer classify them as mammatus.
Looking W:
It was also quickly apparent that the the virga was actually precip was reaching the ground to my WSW – in the form of large snow flakes!
Snowburst!!
We were soon experiencing a moderate snowfall, and I did hear a rumble of thunder at 1904z! This was an interesting event – I have never seen mammatus precede a precip event, and I have not seen mammatus with snow before.
Also I have never seen mammatus like features grow so rapidly and evolve to significant precip reaching the surface. It would be great to understand why this event occurred – I wonder if it was related to the specific thermodynamics and kinematics at and around the lifted condensation level… .
