Inchoate in Going

I can't get a handle on it,
This momentary thunderhead,
Too slow for me to follow it
And too quick for me to catch it,

Accruing as it disperses
In blue-bottomed ships with white sails,
Cumulonimbus tenuous,
Promising unpredicted storm.

When I turn my back it puffs up,
Piling grandeur on grander peaks,
Glories on glorious La Sals,
Rock clouds themselves, ages slower.

When I turn back to study it
It seems just about to dissolve,
A Chesire-cat glower, no more,
Not a threat, not a storm, nothing

Much to get exited about,
Until the random wind picks up,
Teasing leaves with apocalypse,
And now and again comes the end.