The phrase "an ominous development" is correct and usable in written English.
It can be used to describe a situation or event that suggests something bad or threatening may happen in the future.
Example: "The sudden increase in tensions between the two countries is seen as an ominous development by international observers."
Alternatives: "a troubling sign" or "a foreboding situation".
For owners of traditional malls, it is an ominous development.
Yesterday's violence in Cairo marks an ominous development in the story of Egypt's unfinished revolution.
His erosion of European trust played a far greater role in what is actually an ominous development.
But Raanan Gissin, an aide to Prime Minister Ariel Sharon, called the latest arrests "an ominous development".
The recent spate of seemingly homegrown terrorists seeking to collaborate with al-Qaeda is an ominous development.
(In an ominous development, Miami this past fall experienced several very high tides at times of the month when, astronomically speaking, it shouldn't have).
And lawmakers in Massachusetts recently voted to issue licenses for a slots parlor and three full resort casinos — an especially ominous development for the Connecticut casinos, which draw about 30 percent of their clientele from Massachusetts, because many gamblers are ruled by what is known in the business as the law of gravity.
In a potentially ominous development for Ford, Blueovalnews.com, a Web site devoted to news about Ford, plans to announce on Friday that it will share information with regulators about patterns of defects in Fords.
The Times story also contained a potentially ominous development for Trump: "The strain, though, exists on both sides.
In a more ominous development for the protest movement, the Russian television channel NTV broadcast a documentary not long after the May 6 protest asserting that more than an unruly crowd was to blame for the violence.
It's a very ominous development". The largest personal-injury award ever paid by the city involved a former Coliseum groundskeeper who was shot by an off-duty police officer in 1987 and left a paraplegic.
