Many of the links I collect via the incoming seem to portend what's on or over the horizon. Bellwether tolls just the right sheepish note of foreshadowed doom and inevitability... (see some examples)
Bellwether Wikipedia
OED
4.b.1876 Something that establishes or signals a widening trend; an indicator or predictor of the way in which something will develop or change. Frequently as a modifier, as in bellwether county, bellwether state, etc. Originally and frequently in political contexts.1876 Ohio, the bell-wether State of the Union, is a ‘close’ state... The Ohio election takes place three weeks in advance of the National election. Cincinnati Enquirer 15 January 4/2
1908 If the dispensary is not a success here it will not be a success anywhere. Craig will be a fine bell-wether county. Vinita (Oklahoma) Leader 9 April
1968 The number of robberies—the offense that crime experts consider the bellwether of a nation's tendency toward criminal violence. International Herald Tribune 3 September 7/3
1993 Steinem, always a bellwether of the going trend, aligns the passion for witchcraft with feminist political doctrine. Harper's Magazine July 7/2
2024 Nuneaton is traditionally a bellwether constituency in general elections—when the Tories held it in 2015 it was an early sign that they had defied expectations to win a majority. Guardian (Nexis) 5 April (Politics section) 5