Even though the temperature has been below freezing constantly since beginning of december, it took a long time this year until the northern Baltic froze, since the water escaped through Danish channels due to wind direction and air pressure. Water level is one meter lower than usual, but when that movement stopped, ice accumulated very quickly.
http://arctic.atmos.uiuc.edu/cryosphere/
About snow coverage then:
One would assume, that global warming, if it existed in any statistically significant way, would result the rain coming down in a water state of matter, not snow.