Prepare for a sharp weather rollercoaster this week, culminating in a severe blast of arctic air that will send temperatures plunging well below freezing for the weekend. Wednesday features abundant sunshine, the region remains in a cold pattern with overnight lows dipping near or below the freezing mark. A brief moderation is expected Thursday, as southerly winds push daytime highs into the low 60s under partly cloudy skies. However, this relief will be exceptionally short-lived. A potent cold front is scheduled to sweep through the region on Friday, ushering in a renewed surge of arctic air. Unlike typical systems, this front is expected to pass through mostly dry, but the temperature impact will be drastic…