ROCHESTER, N.Y. – Are you feeling waterlogged by all the wet weather this past week? You are not the only one. As a meteorologist, I am always scanning the horizon for a break in the pattern. Over the past seven days, rain gauges across the region have collected anywhere from 1.5 to over 3.5 inches of rain. That is more than half of the typical monthly rainfall and we are only a week into May.

One of the challenges in weather communication is clearly explaining the probability of precipitation. Sometimes we assign percentages based on location. For example, a 70 percent chance of rain on the east side of the viewing area and only a 30 percent chance on the west. But more often, we forecast the percentage of area coverage for a broader region, like the entire seven-county area, during a specific time period.

So, what does a “30 percent chance of rain” really mean? It indicates there is a 30 percent chance that any given location in our viewing area will receive measurable precipitation during that forecast window. Here is a quick guide we use:

• Isolated showers: 20-30%
• Widely scattered: 30-40%
• Scattered: 40-60%
• Numerous: 60-80%
• Widespread: 80-100%

You can see these probabilities in action every day on our News10NBC First Alert 10-Day Forecast. They help provide more clarity about what to expect and whether or not to grab that umbrella on your way out the door.