The four were walking to the shopping center in that town with plans to shop for their winter clothes for their next destination and other equipment they may need for the road. Even though they could just summon out something using magic, the girls decided a shopping spree was in order.
"What if we get in a situation where our magic gets cancelled again? We need to be prepared," was their excuse to force shopping upon the unwilling two.
Lisa and Dawn were just girls being girls so the other two just let them have their fun. Lyte and Snow decided they would just summon out their own winter outfit later.