18z HRRR trickling in has 9 inches through daybreak.
There was a big CSTAR study on mesoscale precip forecasts, and one of the finding from the modeling team was that the HREF max products are usually a good red flag indicator of potential. Like if the HREF says 10 inches max, that means the environment CAN support 10 inches and don't sleep on it. You may only get 5, but you should be paying attention. The current HREF does indeed have some 10 inch amounts in CT, and even 5 inches in 6 hours.
The way the 3 hourly mean/max QPF forecasts back build towards HFD tells me that it's going to be somewhere southwest of the current QPE max near PVD that jackpots.