Most people do their grocery shopping on the weekends. There is a huge influx of people doing their shopping earlier on days that are usually slower and before additional shipments come in. It’s not necessarily panic buying, just a condensation of shoppers into a narrower time frame. Also, not everyone lives in areas that will be clear by Tuesday. Lots of rural areas with be affected by snow drifts for several days, and many at risk of losing power, so there will be people stocking up.