KAMPALA, Uganda—Drought conditions have left an estimated 13 million people facing severe hunger in the Horn of Africa, according to the United Nations World Food Program. People in a region including Somalia, Ethiopia, and Kenya face the driest conditions recorded since 1981, the agency reported Tuesday, calling for immediate assistance to forestall a major humanitarian crisis. Drought conditions are affecting pastoral and farming communities across southern and south-eastern Ethiopia, south-eastern and northern Kenya, and south-central Somalia. Malnutrition rates are high in the region. WFP said it needs $327 million to look after the urgent needs of 4.5 million people over the next six months and help communities become more resilient to extreme climate shocks. “Three consecutive failed rainy seasons have decimated crops and caused abnormally high livestock deaths,” it said in a statement. “Shortages of water and pasture are forcing families from their homes and leading to increased conflict between …