RaVeNStOrM

THUNDERSTORM T0024
Date: Friday 28th May 1999   Time: 00:15 BST
Location:
Macclesfield, Cheshire UK
Path: Overhead

Synoptics:
Spanish Plume, intense enough to form a low centre
Duration: 2 hours 15 minutes
Type: Linear mid-level Multicell
Average lightning type: C-C Crawlers
Average discharge rate: 140s (approach) 145 s (overhead) 54 seconds (departure)
Footage Quality:
VHS / Hi-8

 

T0024 is the most photogenic thunderstorm I have filmed so far (1997-1999). Not the loudest which still goes to T0011, but the best displays of C-C spider-lightning were captured.

I was expecting a Spanish Plume outbreak for a couple of days following the forecast, with a broad elevated mixed layer coming in off Iberia destabilised by a sharpening trough extending from a parent Atlantic low (classic). I was so convinced something would happen I placed a bet with someone at school that it would happen (and clearly won).

The evening sky was humid and still, with advancing chaotic sky from the south heralding the approach of the upper trough which was lifting the entire atmosphere ahead of it. I had to wait up to see what would approach from the south.



When I saw a few flickers of lightning on the horizon at ten past midnight on the 28th it was game on! Remember, these were the days of no live radar loops - I had zero internet (an Amiga 1200 and no smart phone) - I was flying off whatever TV broadcasts I was able to catch, and Ceefax :)



When it came closer, large Anvil-crawling C-Cs with many branches were becoming visible in the distance to the south west. On final approach the cell was producing much larger C-Cs crawling across the sky followed by a strange ambient silence to the thunder, due to how high up in the atmosphere they were occurring. There wasn't much precipitation as the entire cell passed over Macclesfield, and it was actually showing signs of weakening at one point. With no latest radar imagery to ascertain what was happening out there, I believed that curtains were starting to draw on this cell.

As the cell started to move away about half an hour later it started to show signs of reinvigorating, starting off with a large C-C spider-lightning with four separate streaks crawling cross the sky in different directions. Unfortunately only one of the streaks was caught on camera as it was so vast. Then shortly after there was a large multi-C-C spider discharge less than a mile NNE (shown above frame-by-frame). Probably one of my best captures to date. The thunder wasn't as loud as I was expecting, more crackly than explosive, likely as the charge was distributed evenly across multiple branches (low-amp).

As the storm, clearly linear in nature (evidenced from the grabs above), passed over the Pennines the discharge rates increased again and the clouds lit up from base-level giving away the structure. A classic bubbly, linear elevated cloud base is shown at the back edge of the storm, likely where the updraught feed is, with the storm forward-sloping with the vertical wind shear expected from a dynamic system. This is why the Anvil Crawlers preceded most of the rain and normal C-C lightning. Throughout the storm, I think I only saw one distant C-G near the beginning.


SATELLITE IMAGES (Credits)
VISIBLE 27.05.1999 14:28

INFRARED 27.05.1999 14:28
COLOUR 27.05.1999 14:28

VISIBLE 27.05.1999 17:00
INFRARED 27.05.1999 17:00
COLOUR 27.05.1999 17:00

INFRARED 28.05.1999 04:23
COLOUR 28.05.1999 04:23

VISIBLE 28.05.1999 06:49
INFRARED 28.05.1999 06:49
COLOUR 28.05.1999 06:49



CHARTS (Credits)


NOAA 500hPa Reanalysis NOAA 850hPa Temp Reanalysis NOAA 850hPa Temp Reanalysis

SFERICS (Credits)
EUROPE 24-hour SFERIC LOCATION 27th
EUROPE 24-hour SFERIC INTENSITY 27th

EUROPE 24-hour SFERIC LOCATION 28th
EUROPE 24-hour SFERIC INTENSITY 28th


 
Mark Seltzer  www.electricsky.co.uk

 

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