What major event in Oklahoma occurred on April 27, 1999?

On April 27, 1999, Oklahoma experienced a devastating tornado outbreak, which included an EF5 tornado that struck the city of Moore. This particular tornado is one of the most powerful ever recorded, with winds exceeding 300 miles per hour and a damage path that extended approximately 1.5 miles wide. The tornado caused catastrophic destruction, resulting in significant loss of life and extensive damage to homes and infrastructure. The event is notable not only for its intensity but also for the impact it had on emergency response and weather forecasting in the region, leading to advancements in tornado preparedness and safety measures.

In contrast, the other options concern events that did not occur on that date or are less significant in the state’s weather history compared to the tornado outbreak. The snowstorm, flood, and heatwave, while they are notable weather phenomena, did not have the same level of immediate and historical impact on Oklahoma as the tornado outbreak of April 27, 1999.