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Please advise which of the following is correct:

It rained heavy / heavily yesterday.

Thanks.
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We need an adverb here, so the answer is heavily.
Comments  
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It rained heavily yesterday.
It's heavy raining or heavily raining? !
Orpheus We need an adverb here, so the answer is heavily.

heavy may also be used as an adverb. See: http://www.dictionary.com/browse/heavy (#34)

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Once your green tree thrives

You can climb above…

View ... others below

Even if that day heavily rains...

Once your green tree thrives

You can climb above the fray

And view the crowds below

Even through a heavy rain