terminology - Collective noun for lightning(s) / thunderbolts

What is the collective noun for lightning(s) / thunderbolts?

A ________ of thunderbolts/lightning(s)

Can we use the plural form of lightning with a collective noun? Or should it stay in singular form?

For example:

The valleys of Grand Canyon were being struck by a ________ of lightnings and rumbling like a giant open-air opera house with the following thunders.

(Note: This would be a literary sentence than an everyday speech)

Note: A single lightning event is mentioned as a flash and if it hits the ground or an object, it is mentioned as a strike.

Note 2: Lightning is generally a mass noun but it can be used as a count noun also, especially in literary sense. OED has a definition for the literary sense as a count noun:

[count noun] literary a flash or discharge of lightning: the sky was a mass of black cloud out of which lightnings were flashed.

You can find literary usages in Google Books as well. Plural form was more common in 1800s and the usage has dropped dramatically but there are still some contemporary usages.

Lightning is used in plural form in technical contexts also. Below are the examples from a technical book called "Lightning Physics and Lightning Protection" (by By Eduard M. Bazelyan, Yuri P. Raizer) also.

The statistics of flight accidents show that aircraft of identical size may differ considerably in the capacity to excite lightnings.

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The lightnings people observe most frequently are descending discharges, which originate among storm clouds and strike the earth or objects located on its surface.

Thunderbolt is a count noun.

Note 3: Below is a similar question asked before:
Collective Noun for Fire

The difference between fire and lightning in the context of countability is that fire is also both countable and uncountable but both senses have a common usage.

Answer

Lightning is the generic term for this weather phenomenon. In normal, non-technical English an individual instance is a lightning flash, a bolt of lightning or a lightning strike. There is no collective noun for them.

However, you could refer to a set of lightning flashes, bolts or strikes by one of the nouns used to describe a group of objects or phenomena. I would suggest something like a succession of lightning flashes. Besides electrical storm, the term lightning storm also exists as a way of implying or describing multiple lightning flashes.

Other suggestions in a non-exhaustive list of possibilities: barrage, volley, parade, procession, sequence and display, depending on which aspect or characteristic of the irruption of flashes seems most salient for the context in which you are describing them.

Because discharges of lightning are ephemeral, and do all not occur simultaneously even during a violent electrical storm, they do not exist as groups in the same sense as a group of children exists, say -- which would be one reason for the lack of a collective noun.