"Vort" is short for vorticity, the spin of the flow. In practically any weather event, you want vorticity to be as strong as possible for good results. Stronger vorticity = stronger lift = stronger storms. Ideally, we'd want the strongest vorticity just ahead of an approaching weather system for the greatest impacts (just as it rolls through). Here is the nws glossary definition. "A measure of the rotation of air in a horizontal plane. Positive (counter-clockwise or cyclonic) vorticity can be correlated with surface low development and upward vertical motion (in areas of positive vorticity advection)."
Most such maps have the intensity of vorticity shaded yellow as weaker flow, orange-ish for more moderate flow, and red for the strongest vorticity.
Maybe psu can elaborate more on specifics of vorticity maps.