Date: Sunday 19th June 2005
Time: approx 1500-1800 BST
Macclesfield, Cheshire UK
Path: Likely overhead, travelling NE

Continental Plume, strongly surface heated and destabilised in proximity of trough
Type: Surface-based linear Multicells, possible embedded Supercells (unknown but correct environment)
Footage Quality:


This outbreak was one of the most aggressive thunderstorm squall-lines the northwest region has seen in years, and an excellent example of when all the right ingredients come together in the atmosphere to generate a severe thunderstorm. Unfortunately, I missed it by an hour or two as I was arriving back from the south of England at the time. However the cumulonimbus towers reached such heights I could see them from Reading as I set off somewhat 170 miles away. They were enormous, likely hitting -55C tops, and were developing rapidly with large CAPE values. 

Weather situation
All the right atmospheric ingredients came together on this day. The fuel was there with high wet-bulb potential temperature values (WBPT) existing over England by advection from the continent (plume), with the boundary layer heating strongly below it by the Sun. A long-wave upper trough associated with an approaching Atlantic depression advanced into this air mass, just enough to focus development in the north and west of the plume (linear development). A slight inversion likely existed above the boundary layer which increased CAPE (Convective Available Potential Energy) values. All that was required was some form of initiation to set it all off, which judging by the fact the cells appeared to be strongest to the east of high ground in satellite imagery, may have been some form of surface convergence or lee-low.

Large cumulus fields were already forming in the North Midlands and Yorkshire areas by midday as the daytime heating started hurtling towards the 30s, showing that radiative (sensible) heating alone was enough to start destabilising the atmosphere. As the satellite imagery shows, the cap-breaking up-scaling convection started forming in these fields by 1400BST.

What I witnessed
By the time I had driven closer to the development, now lying in a line across much of the North Midlands and Yorkshire, the cloud base was visible and very ominous-looking with deformed stratus rolls and very dark rain curtains. As I approached Congleton it wasn’t raining a great deal, however the roads were completely flooded with fountains of water spewing out of the drains, so the storm must have just gone through before I arrived. Distant thunders were still rumbling away to the east with the odd distant flash of sheet lightning occurring. By the time I got back to Macclesfield the storm was long gone and only a few distant rumbles were heard from the east.

Accounts of the ferocity of the storm system were soon spoken on the news with power outages, widespread flooding, golf ball hail and even a few lightning injuries from tremendous intensities of C-G. These intensities were reflected in Wetterzentrale’s lightning “sferics” charts at the time (C-G strikes detection).

APPEAL: If anyone has any footage, photos or eyewitness accounts of these storms to share on this page (credited to yourselves of course) I would be more than happy to display them.

Links relating to this thunderstorm outbreak:


VISIBLE 19.06.2005 15:31
VISIBLE 19.06.2005 15:31 + Grid
INFRARED 19.06.2005 15:31
INFRARED 19.06.2005 15:31 + Grid
COLOUR 19.06.2005 15:31
COLOUR 19.06.2005 15:31 + Grid

CHARTS (Credits)

SFERICS (Credits)


© Mark Seltzer  www.electricsky.co.uk


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