FUNNEL
F0001 Date: 10th July 2004
Time:
10:37 BST Location:
Macclesfield, Cheshire UK Path: A few miles northwest
Synoptics:
Polar Maritime in slack flow (convergence enhanced) Duration: ~5-10 minutes Type: Potential Supercell - horseshoe evident Average lightning type: None Average discharge rate: 122 seconds (over 1 hour where rates were up
and down)
Footage Quality: VHS / Hi-8
I
spotted some mesocyclonic activity to the northwest of Macclesfield in a
similar location as the tornadoes of
T0014 and
T0027 (might be the "Cheshire
Gap" effect encouraging this location!). The synoptics were similar to
T0014 as well, only drier and warmer. The cloud base actually took the form
of a classic supercell in rotation mode - the "horseshoe" clearance
approaching from the left, and the mesocyclone hang-back just northeast of
it with a rotating dangly bit under that. The
"horseshoe", according to US Midwest chasing circles, is renowned
for being a precursor to a tornado and is evidenced well in proper
supercells.
The dangly bit
(small scud funnel of sorts) is the main focus of this footage, which upon
time-lapsing turned out to be rotating into the updraught. The lowered condensation point
was likely caused by cooler air
being sucked back into the updraught, indicative of tornadic genesis. The rotation
was slow, barely visible in real-time, but as mentioned it is better
evidenced in the timelapse (video above). This vortex is exactly where one would expect
a tornado to
emerge if vorticity was stretched enough.
However, we're dealing with the UK here. CAPE is usually weak,
so this just remained a scud vortex that never wrapped into a more defined
funnel or touched the ground. The vortex lasted for about 7 minutes before
ascending back into the updraught.
No
thunder or lightning activity was observed from my perspective, but may have
been downstream. This is also common in sheared supercells not to see much
lightning activity around the mesocyclone itself, let alone several miles
south of it.