Southwest winds swept May-level warmth across the Midwest on Monday, sending temps into the 70s across northern Illinois for the first time this spring. The surge in temperature will be brief. By Tuesday morning, a cold front will have switched winds to the northwest, signaling the arrival of moderately cooler air. More significant chill is to arrive midweek as deepening low pressure over the Plains strengthens a northeast wind flow. Highs on Wednesday are expected to run 25 to 30 degrees lower than Monday’s balmy readings. Another sign of spring are severe thunderstorms. Hail 3 inches in diameter pounded Princeton, WV Monday afternoon. More strong storms are forecast for the Southeast on Tuesday before the focus of activity shifts back to the west. Severe weather is possible across parts of the central Midwest on Thursday, while heavy snow accumulates from Nebraska, to northern Wisconsin.