Ever since Hurricane Harvey, a lot of people living in and around Houston become nervous at the mention of widespread, heavy rainfall. The mere suggestion of even minor flooding heightens tension. And after surviving Harvey, we certainly understand why.

In the months after Harvey, Matt and I got together to try and determine what, if anything, we could do to help ameliorate this situation. Eventually, Matt hit upon the idea of a “flood scale” that residents of the greater Houston area could use to calibrate their concerns about upcoming flood events. Over time, the scale evolved into a rating from Flood Stage 1 (street flooding) through Flood Stage 5 (Hurricane Harvey). Here’s what we came up with:

This scale is not officially sanctioned by any government organization. Nor are we seeking to usurp any authority from the National Weather Service—they command our highest respect in issuing flood watches and warnings. Rather, we felt there was a need for something like this, in advance of significant weather, to help our readers set expectations and manage their own anxieties. So we’re providing the scale as such a service. It remains a work in progress.

In truth, there are many, many ingredients that will determine the impact of a flood: the total amount of rain, intensity of hourly rainfall rates, how long the rains last, the preexisting saturation of soils, the time of year, and more. This scale attempts to incorporate all of those factors into the ranking the impact of a flooding event. It is not perfect, nor purely quantifiable, but is does represent our best attempt to determine what residents can expect.

So why are we introducing this scale now? Because we anticipate needing it for the coming Thursday through Saturday period. Absent a major change in the forecast models, we’ll begin to use the flood scale beginning in Tuesday morning’s post. For what its worth, our overall thinking hasn’t changed, we continue to see the potential for 3 to 10 inches of rain through Sunday morning for the Houston region.