Spring is a meteorologically volatile time of the year in Chicago and the next few days will provide a prime example. Temperatures surged into the lower and middle 50s Monday as the city basked in unlimited sunshine, the city’s first 100 percent sunshine day since January 18. Tuesday could be the second as temperatures surge to unseasonably mild levels in the lower 60s for the third time this month. Conditions will go downhill rapidly after that, as showers develop Wednesday night in advance of intensifying low pressure. The rain will become steadier and heavier by daybreak Thursday as an influx of colder air turns the rain to snow. The snow could accumulate as temperatures slide toward freezing. Clearing arrives Thursday night setting the stage for a couple of seasonably chilly days followed by weekend warming.