The 2nd week of March can sometimes break down into a more bowling ball “spring” type pattern but we’ve also seen it behave like mid-winter too (2014 or 2017 come to mind with these massive longwave deep troughs over the east with upstream ridging in the west)….2018 was maybe a hybrid…massive NAO/AO blocking and a lot of cutoffs but there was a thermal gradient to tap into that is often not there in, say, early to mid April, so we got those epic snow bombs in March ‘18.
Either way…I don’t have much to add on the SSW front for you and radarman’s discussion but I don’t put much stock in them from a LR perspective since they are so hit or miss on the effects…usually by the time we can figure out if it’s going to cause favorable blocking, that said blocking is already seen by mid-range ensemble guidance and there’s no need to try and read the tea leaves at 10mb or 50mb.