FROM MY DOWNSTATE FRIEND (when we both were puzzling about the dumpling ice and how it forms I told her I was gonna try to find out; she beat me to it and this is her response); Thanks Anne-Marie Woodruff!!! (Hard to get use to your married name!)
Well, I'm no 'expert', but I did stay at a Holiday Inn Express last night. :-)
I did some research & here's what I found:
turbulence (stream flow and lake currents) circulates heat throughout the depth of streams or the lake epilimnion and therefore dynamic ice forms from frazil ice, which is ice that has formed in quiet water and become suspended in the flow
The frazil ice crystals agglomerate and float to the surface to form frazil flocks or slush floes, which oscillate in the turbulent water, becoming exposed to cold air and freezing into ice pans (pancakes). Ice pans collide with one another , developing a dish shape (circular and concave). Frazil ice and ice pans are generated from the same stretches of calm water, on successive nights and / or cold days until the concentration of ice pans results in a continuous ice cover. The ice cover extends upstream from ice bridges that form over clam water or constrictions in the channel. On the St. Lawrence River, ice pans travel as much as 40 km per day.
in the more turbulent flow, the ice pans can be destroyed and thus an ice cover may be thin or absent from rapids, except possibly in cold climates or cold years
ice also can form in the still water behind objects on the stream bed (e.g., boulders); this anchor ice can restrict the flow possibly causing winter flooding or it can break off and float to the surface
3 months ago