The back landing
Winnow's bar is a red building is located off the courtyard in Cyria Gardens (L3S on the map) and across a small alley just south of the quarantined building with the Nest Keeper (U6F on the map). Behind the bar are three guards: two women and a man. They are chatting with each other as they patrol just below the landing and back door to the bar. Next to the landing is a table with some Howler Dust.
The door on the landing leads to the second floor hallway beside the kitchen which leads to the bar area. From the main room of the bar, you can go behind the counter, through a pantry and finally into the kitchen.
Kitchen area[]
The kitchen can be more directly accessed via the window off the landing. There is one person inside, presumably "Cecil", the head bartender. Going through the kitchen leads to a small pantry with a Chloroform Bottle, then the bar area.
Private rooms / Bar area[]
The bar area has a fair bit of loot. The main room has a round table in the center with 2 Pistols, some Pistol Bullets, a flask of S&J Health Elixir and a bonecharm. The counter has a cash register with some coins inside, a few more coins on the counter itself and a threatening note underneath. On the shelves behind the counter are some Bathing Salts and Orbon Rum.
Rooftop patio[]
Initially there are two women on the roof: "Beatrix" and her lover, an elite guard. You can listen to their conversation, after which the guard re-enters the building and heads downstairs.
This area also provides easy access to a third floor balcony off the quarantined building next door.