Weather system – horrible – often cold – crud! (8,5)
I believe the answer is:
occluded front
'weather system' is the definition.
The definition and answer can be both types of natural phenomena as well as being singular nouns.
Perhaps you can see a link between them that I can't see?
'horrible often cold crud' is the wordplay.
'horrible' indicates an anagram.
'often'+'cold'+'crud'='oftencoldcrud'
'oftencoldcrud' anagrammed gives 'OCCLUDED FRONT'.
Can you help me to learn more?
(Another definition for occluded front that I've seen is " Weather-map feature".)