ROCHESTER, NY (WROC) – Living in Western New York means we’re no stranger to lake effect snow and how changeable it can be. Lake effect can be very localized depending on the situation. In one town it’s sunny, meanwhile the next town over is already under a foot of snow. It can often be a challenging forecast, but we usually have a good idea on where we can expect to see lake flakes fly depending on the wind direction.
Remember that a ‘west’ wind means winds are coming from the ‘west’, or a 270° wind.
Wind plays a big role in which lake the lake band comes from, how strong the lake band can be, and the general placement of where the band will set up.
A typical rule of thumb and a common way we describe the direction that lake effect snow will come from is using degrees as on a compass, where north is 360 degrees, east is 90, south is 180, and west is 270. Typical wind directions that provide Western New York with lake effect snow are about 250-260 degrees under a southwest flow across Lake Erie, and around a 275-280 degrees under a northwest flow across Lake Ontario.
How to read the maps
Those shaded in dark blue are in the sweet spot. You are in just the right path to see lake flakes under a wind direction like this. The light blue shade accounts for the variability in lake bands. Which wind direction gives you lake snow? Here’s a general guide to figure out if you’re in just the right spot for lake effect given where the winds are coming from:
Northwest Wind Flow (~275-290 degrees)
Sometimes under this specific wind flow if aligned just right, you can get an “upstream connection” from the Georgian Bay connecting lake effect bands from one body of water to the other. We often look at this lake-to-lake connection while forecasting for a better idea at when and where to anticipate a similar lake band to form and head our way. A secondary connection also tells us the band has a good source of moisture already, and will likely provide us with higher snow totals given the extra boost in lift and moisture.
Southwest Wind Flow (~250-260 degrees)
Lake effect snow bands under this type of wind flow with just the right wind speed and direction can stretch as far northeast as Orleans, Monroe, Wayne County, and even farther. It can sometimes produce lake snow with a secondary band that connects over Lake Ontario dropping snow across the Tug Hill. We call this type of situation a lake band “with legs”. Plus, lake snow can be seen as far south as Wyoming county.
Northeast Wind Flow (~40-60 degrees)
This is a more unique type of wind flow, but it happens more often than you think. Lake snows under a northeast flow have been known to produce some of the bigger snow totals for Rochester, and can be a very localized event.
North Wind Flow (~355-5 degrees)
Typically under a northerly wind flow the entire region is fair game for more scattered variety snow showers and flurries. These types of setups are usually weaker than other wind flows because a north wind flowing over a west to east oriented lake isn’t the ideal wind direction for a strong, steady lake band since the “fetch”, or distance across the lake the wind is traveling over is much shorter. What’s really unique about this wind direction is that it can provide lake effect snow over the Finger Lakes if the conditions are just right.
These maps should be used as a general guide to help give you an initial idea on where to expect lake snow to form. Be sure to always keep up to date with the latest forecast page HERE for a more detailed look when we’re expecting lake effect snow locally in our area.
~Meteorologist Christine Gregory