Phoenix Rainfall Index looks at the big rain picture

Posted: Updated:
(Source: 3TV/CBS 5) (Source: 3TV/CBS 5)
Here's the Phoenix Rainfall Index Map provided by the National Weather Service. Here's the Phoenix Rainfall Index Map provided by the National Weather Service.
Weather stations included in Rainfall Index (Nat'l Weather Service) Weather stations included in Rainfall Index (Nat'l Weather Service)
US 60 flooded on August 3, 2017 at McClintock after nearly 2" of rain US 60 flooded on August 3, 2017 at McClintock after nearly 2" of rain
Pouring at Tempe Town Lake August 3, 2017 (Mike Watkiss) Pouring at Tempe Town Lake August 3, 2017 (Mike Watkiss)
(3TV/CBS 5) -

We all know the “official” rain gauge for the Valley, really just Phoenix, is at Sky Harbor Airport. But a lot of folks ask, "Why the airport?" And a recent email asked why isn’t there some sort of number that is more reflective of the entire metro area?

There is. It’s called the Phoenix Rainfall Index and it’s a relatively new addition to the information that’s supplied by the National Weather Service. You can take a look at it here at http://www.wrh.noaa.gov/psr/PRI/.

It uses data provided by 132 of the Maricopa County Flood Control’s weather stations and the idea is to be more representative of Valleywide rain instead of point-specific reports. Don’t get us wrong. Point-specific rainfall data will always rule, however the Phoenix Rainfall Index lets us come at the data from a different direction. As meteorologist Paul Iniguez says, “It’s a supplement to our current data and gives us a better idea of coverage for the Valley.”

For instance, last Thursday we got nearly 2 inches of rain in east Phoenix and portions of the East Valley. But a lot of the west side missed out completely. We showed you some individual rain reports but the Rainfall Index told us 60 percent of the area got rain last Thursday.

[RELATED: Rain totals on azfamily.com]

So far this summer, Iniguez says there’s only been one day where 100 percent of the rain gauges got measurable precipitation. That was Monday, July 24, when we had mainly morning storms and showers around the Valley.

[SLIDESHOW: Monday rain leads to rescues and flooding]

[READ MORE: Monsoon storms bring flooding throughout Arizona]

[RELATED STORIES: Boy swept by rainwater after falling into canalCar gets trapped on flooded road; driver rescued]

Suffice to say, for most of us, it matters how much it rained in our neighborhood or where we work or where we play. And for that info, the Maricopa County Flood Control has a great website.

But the Rainfall Index will give us another tool to help judge the intensity and area coverage of our rain.

[RELATED: High-tech weather sensors at Sky Harbor record Mother Nature]

[MORE WEATHER GOODIES: Interactive radar map | 7-day forecast | Blog]

[SPECIAL SECTION: Monsoon 2017]


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Copyright 2017 KPHO/KTVK (KPHO Broadcasting Corporation). All rights reserved.


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