ROCHESTER, N.Y. (WROC) — From the western shoreline of Lake Ontario to the shores of the Finger Lakes there is a wide range of rainfall totals from the rain Sunday night into Monday morning. From nothing in parts of Orleans County, to close to three inches in Ontario County it was a true feast or famine event.
Rainfall totals from any weather system are rarely consistent over a large area like the one the News 8 Weather Team covers. There are a lot of different factors for this, but a big one is the unique geography we have in western New York.
On the map above some of that influence is clear. Sunday night, a lake shadow set up off of Lake Erie on a southwesterly wind causing rainfall totals in Monroe, Orleans, and Wyoming counties to fall off quickly. The, relatively, cooler and more stable air that comprised the lake shadow made it much more difficult for showers, storms, or really anything to fire along the passing cold front due to the influence of the lake. It also helped to fire off the initial round of storms that contributed to the locally higher totals near the finger lakes, an example is below.
NOTE: The tweet below is from July 24th, and the weather discussed in it has already passed.
Further south, it was a different story. Without the cool stable air off the lake, storms and downpours were uninhibited comparatively. Initial storms through the evening were able to form ahead of the front, creating splotchy areas of high rainfall totals while most were still awake. Later as the front itself pushed through the area, these areas were able to tap into some of the remaining instability in the region allowing a widespread soaking rain to set up and push from west to east.