RAT 5 , It is more or less the approach ban that I had in mind , even though strictly speaking by the alteration of the approach ban definition a few years ago , I should be getting the latest WX at around 1000 agl in which case for NPAs I could be below the DA.
On a practical level if I were to be getting continuous reports from my destination that vis. is above minimums but getting a cloud base well below the MDA , then I ought to start thinking on which basis I could be justified not going for the approach and diverting to my alternate . If in any case I am bounded only by RVR or visibility , I could shoot the approach (even though I know that cloud base will prevent me from seeing anything ) and not care of the outcome