The icy snow bomb is set to stretch from Oban, in Scotland, down to Plymouth in the first week of March. New maps from WXCharts, which uses MetDesk data, show a large purple mass sweeping across the UK.  The colour indicates the country will be plunged into below zero temperatures, with some regions seeing as much as 23 inches of snow being dumped on the ground. Weather maps forecast the weather will make a chilly turn at about 6pm on March 5.