More than 100 million people in the U.S. are in the path of an expected massive March storm starting Friday. It’s a sprawling system that may bring blizzards, tornadoes, fires and flooding as it tracks across the Great Plains eastward. Moisture and heat from the abnormally warm Gulf could fuel heavy rainfall that is raising concerns for flooding from the Central Gulf Coast through the upper Ohio Valley. Tornadoes are possible in the nation’s heartland. Scientists said the storm’s strength and potential for far-reaching impacts is notable, but its timing isn’t unusual. Extreme weather can pop up in spring because storms feed on big temperature differences between the warmth that’s starting to show up and lingering chill of winter. More than 100 million people in the U.S. are in the path of an expected massive March storm starting Friday. It’s a sprawling system that may bring blizzards, tornadoes, fires and flooding as it tracks across the Great Plains eastward. Moisture and heat from the abnormally warm Gulf could fuel heavy rainfall that is raising concerns for flooding from the Central Gulf Coast through the upper Ohio Valley. Tornadoes are possible in the nation’s heartland. Scientists said the storm’s strength and potential for far-reaching impacts is notable, but its timing isn’t unusual. Extreme weather can pop up in spring because storms feed on big temperature differences between the warmth that’s starting to show up and lingering chill of winter. AP Technology and Science