hai mujhe abr-e bahaarii kaa baras
kar khulnaa
rote rote ;Gam-e farqat me;N fanaa ho jaanaa
1) to me, the raining/bursting and opening/unravelling
of the spring rain-cloud is
2) weeping and weeping, in the grief of separation, to become obliterated
barasnaa : 'To rain, be wet; to fall like rain, fall in showers, be poured or showered down; to be showered, shed, scattered; ... to burst, discharge (as a boil)'. (Platts p.147)
khulnaa : 'To open, come open or undone; to open, expand... ; to open out, unravel; to be opened (as a knot)'. (Platts p.871)
That is, to weep and weep until I die is for me a cause for joy. I consider it to be like the way the clouds rained down and became a cause for joy. The excellence in this is the freshness of the simile. (43)
== Nazm page 43
Urdu text: Vajid 1902 {48}
The refinement and colorfulness of the simile is worthy of praise. (109)
This verse is an obvious companion piece to {48,5}. Compared to that one it's an even clearer example of 'elegance in assigning a cause', because the equation is made explicit. The speaker maintains that in his opinion the bursting open and raining down, and thus the vanishing, of the spring rainclouds 'is' their weeping their hearts out in the grief of separation, until they become entirely empty and obliterated.
Thus the macrocosm is identified with the microcosm: the causes that inform the lover's behavior operate on the spring rainclouds as well. Not that this claim is made with a show of objectivity: on the contrary, it is true 'to me' [mujhe]. But what else does the ghazal universe consist of, except the passionate lover's subjectivity?
For another example of the 'spring raincloud', see {33,7}.
For an invocation of the 'rainy season' that isn't necessarily equated with
spring, see {48,10}. And for a general discussion
of the fascinating problem of 'springtime' versus the 'rainy season', see
{49,4}.

Hali:
That is to say, to weep and weep in the grief of separation and be finished off is, in my view, as commonplace a thing as for the spring clouds to open and rain down. This is an entirely original simile.
==Urdu text: p. 144 in Hali, Yadgar-e Ghalib