The atmosphere's water-holding capacity increases by about 4 percent for every 1° Fahrenheit (0.6° Celsius) rise in temperature. This effect is similar to the difference between a warm bathroom and a cold bathroom: the mirror fogs up more when the air is warmer.
Extreme precipitation is likely when a storm passes through a warmer atmosphere holding more water. In warmer months, it takes the form of torrential rainstorms; in winter, blizzards are more likely.
At the same time, most regions, in the face of warming temperatures, are losing snow cover on the ground that lasts longer than 30 days. Winters are shorter, fewer cold records are set, more precipitation is falling as rain and less as snow—although whopper snowstorms are even more likely in some places—and snowpacks are shrinking and melting earlier. Whether precipitation falls as rain or snow, these extremes can heighten the risk of flood, and cause economic and social disruptions for communities unprepared to cope.