HI, thanks for contacting Ask Extension. 

If your weeping cherry tree is not flowering, possible reasons include insufficient sunlight, inconsistent watering, overfertilizing, pest or disease presence, and environmental stresses.

It looks like sunlight is not the problem but be sure that it is not getting shaded for part of the day.  It needs at least six hours of full sun.  Keep an eye out for insects like aphids, spider mites and borers or signs of disease and control as needed. Stressed trees can have limited flowering.  Consistent water is also important for flowering.  Over fertilizing with too much nitrogen can limit bloom in favor of lush leaf growth.  Broadcast lawn fertilization (usually high nitrogen) can be a source of overfertilization.  Nutrient issues (other than nitrogen) can be identified through a soil test (Home | MSU Soil Test). Pruning at the wrong time can remove or reduce flower buds prune late winter or early spring.  Overly aggressive pruning of healthy branches can impede flowering. Weather can also impact blooming.  Check out the following link:

About - Tree Fluent

I hope this helps.