What's weather and attractions of Guiyang in late April? Flowers blooming? Local products? Shopping?

The average temperature is around 15 to 20C during that time and for attractions, I think Jiaxiu Tower, Qingyang Ancient Town and Huangguoshu Water Fall are worth seeing.
For more attractions, you can refer to https://www.travelchinaguide.com/attraction/guizhou/guiyang/ to find more attractions in the city.
April may not be a good time to see the flower blooming in the city.
For local products, three kind of Chinese medicine are very famous and they are gastrodia elata, lucid ganoderma and Eucommia ulmoides and you can buy some. Local tea is also famous and you can buy in the supermarkets. Batik artwork is worth buying as gifts and you can buy them at attractions.
For shopping, what kind of products of you want to buy? For buying clothes, you can go to Flora Plaza to have a look.