The word <em><u>"ominous"</u></em> has a <u>negative connotation</u> because it refers to something <u>threatening</u> or unfavorable that may occur.
The <u>kind of weather</u> that can be described as <u><em>"ominous"</em></u> would be tsunamis, floods, tornadoes or thunderstorms, which tend to cause devastation or disaster.
