Understanding Rainfall Rates

20 Jan 2021, 8:30 am

Destructive rainfall isn’t just about frequency. Did you know that 2” of rain in the Southeast means something different than 2” of rain in the Southwest, and it all has to do with timing.

Rainfall rates measure the intensity of rain within a certain period of time which is different from rainfall totals, the overall amount of rain expected to fall during a storm.

“When we are talking about rainfall rates of high intensity we are looking at those time scales under one hour,” said David Gomberg, National Weather Service Los Angeles/Oxnard.

These rates are calculated by using rain gauges and Doppler Radar. “Typically on the order of hourly rainfall estimates and also instantaneous rainfall estimates we kind of use a combination of both of those with the rain gauges that kind of give us an overall picture of rain rates,” Gomberg said.

This information is crucial to know to determine if there is a threat for flooding, especially in areas like the southwest where the ground does not immediately absorb runoff. This can also lead to mud and debris flow in recent burn scar areas. The higher the rate is in a shorter time span will likely lead to extremely dangerous and destructive events.

Always remember, when a Flash Flood Warning is issued for your community, that means you need to take action as you might have only minutes to get to a safer location.

About the author

Meredith Garofalo

Meredith is a Certified Broadcast Meteorologist as designated by the American Meteorological Society. She was born and raised in Cleveland but has worked from coast to coast covering almost every type of weather. Meredith is a weather, space, and STEM journalist and has been live out in the field during destructive tropical storms on the Gulf Coast of Florida, raging wildfires in Southern Cali... Load Morefornia, and covered the wreckage from tornadoes in the Great Plains. In 2009, she reported on the damaging hail storm during the Sturgis Motorcycle Rally and in 2017, the historic California winter storms that produced record rain totals and devastating flash flooding. Prior to joining WeatherNation, Meredith worked at KEYT/KKFX in Santa Barbara, CA, KOTA-TV in Rapid City, SD, WWSB-TV in Sarasota, FL, and began her career as an intern at WGN-TV in Chicago. She was Santa Barbara's "Favorite Weathercaster of the Year" in 2016 and the Community Partner of the Year in 2017 for her volunteer work with Make-A-Wish Tri-Counties and awarded with the 2018 Valparaiso University Alumni Association First Decade Achievement Award. Meredith is the current chair of the American Meteorological Society's Station Scientist Committee, which focuses on raising greater awareness & outreach when it comes to science education for viewers. She's also an accomplished journalist, producing weather and science stories including rocket launches at Vandenberg Air Force Base and the new GOES-16 satellite and it's impacts on weather forecasting. Meredith was personally invited by NASA's Johnson Space Center to interview astronauts on the International Space Station and was the only meteorologist in the nation to do an exclusive report accompanying the GOES-West satellite from Colorado to Florida, reporting on and covering it's launch in 2018. Meredith's also worked on features that took her paragliding along the coast, white water rafting in Northern California, learning to surf in the Pacific Ocean, and how to be an aerial photographer while flying a single engine plane! Say hi on Facebook, Twitter, & LinkedIn!