The atmosphere above North America and the Atlantic turned violent with increasing frequency in 1995 and 1996, and some researchers expect that trend to continue in 1997. According to an April 4 forecast by William Gray of Colorado State University, Christopher Landsea of NOAA's Hurricane Research Division, and colleagues, the hurricane season of 1997 is likely to be more active than the average year and significantly more active than those of the early 1990s. Gray and colleagues are forecasting 11 named storms during the 1997 season, which lasts from June to December, the historical average is 9.3 named storms per season. The researchers predict 7 hurricanes (average is 5.8), three of which will be intense (category 3–4–5) hurricanes. The net tropical cyclone activity is expected to be 110% of normal.