Extratropical cyclones produce most winter precipitation over the contiguous United States. In GFDL SPEAR, the winter wet bias increases as atmospheric grid spacing is refined from about 100 km to 25 km, with most of the increase coming from cyclone-associated precipitation. Higher resolution could increase this precipitation by changing either the moisture supply that cyclones encounter or their precipitation response to a given supply. We distinguish these effects by comparing cyclones across three SPEAR resolutions. Cyclone number and size change little with resolution, so the precipitation response lies mainly in how much precipitation each cyclone produces and where it falls. Over the eastern United States, a larger fraction of cyclones encounter high moisture flux, and precipitation at a given flux increases mainly under high-flux conditions. Over the western United States, moisture supply and precipitation response change little, while precipitation within the cyclone domain shifts from ocean toward land. These regional contrasts are linked to changes in the background flow and lee cyclogenesis in the East, and to resolution-dependent orographic representation in the West.