Sometimes, the lake effect snowbands can survive several hundred kilometers downstream. To determine the wind direction, examine the 850 mb analysis or forecast. The surface pressure field can be affected by the lakes themselves, and the surface winds are often influenced by convergence over the lakes or into the rainbands. The colder the air, the stronger the lake effect. Air which is warmer than the lakes will do nothing.
Cyclonic curvature favors lake effect snow.
If the 850 mb height contours curve to the left as you go downstream, strong lake-effect snow is more likely. All rights Reserved.