North Bay of Bengal warm pool anomaly
I think the Southeastern Tropical Indian Ocean (SETIO) provides a better hint of what might be happening. It clearly shows a positive pattern since last November. 
source 

I think it might be related to the recovery from the intense 2015 El Niño. If I remember from Lau &amp; Nath, 2003, when you have a warm ENSO, you get a reduction of the Monsoon intensity with lower wind speeds, which results in a reduction of sensible and latent heat loss. Also, the  cloud cover is reduced because of dryer conditions, which results in a larger percentage of the shortwave radiation reaching the ocean surface.

The WTIO seems pretty normal currently, so it suggest the conditions are mostly eastern Indian Ocean related. The altimetry sea surface height anomaly seems to suggest the currents are counterclockwise in the Bay, so the anomaly seems to be a regional effect.