Final answer:
The sentence 'Severe weather is approaching, and residents will need to evacuate the area' is written in a formal and expository style, evident from its direct, informational tone and the use of formal language to convey important details.
Step-by-step explanation:
The author uses a formal and expository style to write the sentence: 'Severe weather is approaching, and residents will need to evacuate the area.' This can be deduced because the sentence provides straightforward information without expressive detail or narrative elements. It is direct and to the point, delivering important details about impending severe weather and the actions that need to be taken by residents, which is characteristic of an expository style. The use of formal language such as 'residents' and 'evacuate' also supports this identification of style. Unlike other styles that may use figurative language or more personal tones, this sentence maintains a professional and informational tone.