Im sorry mate I doubt I can give u any advice,as there is no winter or northern snakehead in SG.But why not give it a try ,if you're fishing at a spot where there are not much weeds around try using sinking swimbait to cover deeper areas,give it a slow retrieve and some pauses.I use this method to make them strike when its raining and when surface lures don't work for them.But still I have to say this method of mine is for aiming giant snakehead which lives in SG hahaha.....so im not sure will it works on northern but no harm trying right hahaha.....best of luck mate,wish you land something big over there.