Based on the description of the weather map, the blue line with triangles represents a cold front, and the red line with semicircles represents a warm front. When a cold front approaches a warm front, it typically indicates that colder air is pushing into an area that had warmer air.
Given this scenario, the most valid prediction would be:
A significant drop in temperature will occur across the area.
This is because the arrival of a cold front generally leads to a decrease in temperatures as colder air moves in and replaces warmer air.