Saltwater River Freeze and Thaw We live in a house overlooking a salt water river. We overlook a cove. The river feeds into Narragansett Bay in Rhode Island. In the 17 years we have lived here, the river has frozen several times. 

In early January of this year there were record breaking low temps which were below zero in our area. The river froze solid for a couple weeks. A couple of days ago we had record breaking WARM temps with steady rainfall. The morning after the rain storm we noticed that the bottom of the river was exposed but no water flow.

This is alarming to me because we've never seen anything like this to this extent where it has stayed without the river flowing into the cove for several days. I searched the web and found this site. Hoping someone can come up with an answer! Thank you.
I suspect that rather than an ice jam as suggested in the comments, that this was a consequence of sustained high winds that happened to be blowing in just the right direction, thereby blowing the waters away from the side of the bay to which the inlet / bayou / saltwater river is connected.

Negative storm surge can drain shallow bays, sometimes dropping sea level by several feet. This happened, for example, along the west coast of Florida prior to Hurricane Irma. (That negative storm surge became a positive storm surge when the winds shifted direction.) This happens with great regularity where I live. The bayous later today and tomorrow will be very, very low due to a cold front that is pushing through right now.