"winnow down" is a correct and commonly used phrase in written English.
It is commonly used in the context of narrowing down a large number of options or choices to a smaller, more manageable group. Example: The HR manager had to winnow down the hundreds of resumes to just a handful of qualified candidates for the job.
To winnow down an endless list, I discarded recipes requiring out-of-season ingredients.
The contest involved volunteer "peer review" teams to winnow down about 7,300 official entries.
The editors had an advisory board of about 30 experts to help winnow down possible subjects for inclusion.
This will winnow down the 5,000 names to a typically short list of likely cousins whom you can invite to share both documentary research and DNA results.
At a news conference on Monday, housing officials said they hoped to winnow down the backlog to about 100,000 pending orders by the end of the year.
"I'm trying to winnow down to more of a Frenchwoman's closet: a well-edited collection of essentials with airy space between the hangers".
Budget negotiations have moved slowly in recent weeks, as council members tried to winnow down a long list of spending priorities.
Luckily, there was Allan Abillar, an inquisitive and eminently patient salesclerk, who helped winnow down 50 or so options to 5. A pair of Sugar Cane jeans were on the lighter side, denim-wise.
But perhaps it's Hilary Mantel, the recent winner of the Booker Prize, who shows how much verbosity and effort it takes a true writer to winnow down to precision: "Took breath.
The center will help me winnow down the applicants to a much smaller pool of finalists, and then with the help of my assistant, Natalie Kitroeff, I'll choose the winner.
But hope can always use help (ask Obama), so let me provide some advice: come up with lots of captions for each cartoon before you winnow down to the one you want to submit.
