The wind may have been blowing eastward, and possibly NE to SE. I went looking for some archive wind data, but it's not easy to find. I did find some data on the jet stream, but it only goes as far as Finland.There is some confusion over the light wind direction at the time. Was it blowing south, a south-wind or a southerly wind? From the delayed and then cancelled order to evacuate Nyonoksa I got the feeling that, at the time of the accident the wind at the test platform was blowing towards the NW, away from Nyonoksa and Severodvinsk. An expected wind change did not occur, or radiation products did not continue to be released, so the evacuation was cancelled.
Apparently, satellites image the atmosphere, and there are archives of wind/cloud motion over much of the earth. Ostensibly, there is satellite imagery from UK, Norway, Sweden, and/or Finland, and perhaps Germany. I have seen satellite imagery from NOAA, but I can't find the specific satellite at present.
On August 8/9, there was a low pressure system over Sweden and Finland, so if the pressure was greater over White Sea, then the winds would probably blow westward or to SW.