You might have heard us talk about rainfall rates with the US National Weather Service Los Angeles/Oxnard during & after the catastrophic Southern California mudslides. Meteorologist Meredith Garofalo explains what they are and what role they play in forecasting. MORE -> http://bit.ly/2EQPAN3
Posted by WeatherNation on Thursday, February 8, 2018
When we talk about rainfall rates during a storm, timing and amount is everything.
“A half an inch per hour is the minimal guidance for debris flow and here we got a half an inch in 5 minutes,” said David Gomberg, a meteorologist at the National Weather Service Los Angeles/Oxnard.
Gomberg is referring to the historic rainfall rates that lead to catastrophic mudslides in parts of Southern California at the beginning of 2018.
“We saw rainfall rates that were anywhere from about four to even six times the rate that we could see for USGS threshold,” Gomberg said.
Rainfall rates measure the intensity of rain within a certain period of time.
That’s different from rainfall totals, which are the overall amount of rain expected to fall during a storm.
Precip totals from our recent storms over CA. Bullseyes near #Montecito & in the San Gabriels. #CAwx #CArain #SoCal https://t.co/CqKjKQY06G
— NWS Los Angeles (@NWSLosAngeles) January 11, 2018
“When we are talking about rainfall rates of high intensity we are looking at those time scales under one hour,” Gomberg said.
Rainfall rates can be measured by a combination of 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.
Crucial information we need to know to determine if there is a threat for flooding or mud and debris flow in recent burn scar areas.
For WeatherNation, I’m Meteorologist Meredith Garofalo