HOW WATERWATCH PRO TRACKS FLOODING
Ever hear "it was a 100-year flood?"
That idea comes from a massive rainfall database maintained by the National Weather Service, called NOAA Atlas 14.
That database shows how much rain can fall at any location—whether it’s over 5 minutes, an hour, or a full day—based on decades of historical weather data.
It tells engineers, cities, and stormwater managers the maximum rainfall expected for storms that statistically happen once every 2, 10, 25, 50, or 100 years.
Does it mean a flood every 100 years?
Not quite - it simply means there’s a 1% chance of such a storm occurring in any given year. As shown in the table, smaller recurrence intervals (like 10 or 25 years) represent more frequent but less intense rainfall, while longer intervals represent rarer, heavier events.
How WaterWatch PRO Shows NOAA Atlas 14 Data
When a location is tracked, WaterWatch PRO automatically connects to its NOAA Atlas 14 table. If the detected rainfall exceeds either the 24-hour or 1-hour probability maximum, users receive a notification.
From their Dashboard, users see the values and compare them with the NOAA Atlas 14 table amount. In this example from Phoenix, 1.42" fell in a 24-hour period, which has a 20-50% chance of happening in any given year.
Why It Matters
Engineers and planners rely on Atlas 14 to design storm drains, detention ponds, bridges, and flood control systems that can handle expected rainfall extremes. The data provides site-specific rainfall values—right down to a GPS point—making it the national standard for determining design storms and managing flood risk.
