What am I to make of a recent night-time sighting (Saturday June 2nd) of a field of nicely formed Cu's with tantalisingly flat bases? They were building up and decaying right throughout the evening, and were still there when I stepped off the tractor and made my weary way to bed a few minutes after midnight ..... They looked pretty impressive in the moonlight - they would have been equally impressive during the daytime - almost certainly more so.
Did the convection extend below cloud base, and if so, why? If they didn't exist as the consequence of lower convection (almost impossible surely) then why the nice steady flat bases? Wind at ground level was pretty well zero; however there appeared to be quite strong winds at higher levels judging by patches of small broken cloud zooming past the moon. There appeared to be no obvious evidence of wave or wind shear other than the Cu's themselves, so this can surely offer the only plausible explanation.
For the locals who know the area, the most impressive formations were over Riverton, and later overhead and to the west of Blyth. I'd estimate bases at about 4-5,000 and tops to 8 or even 9,000 - especially one lone magnificent specimen over Riverton at about 21:00.
It would have been nice to hop in an SLG and go and have a closer look...........
Regards,
Terry
