The National Weather Service issued a flood watch Wednesday for much of inland San Diego County as rain and thunderstorms are expected to continue through this evening, threatening flash flooding and debris flows down slopes stripped bare in wildfires.
The flood watch went into effect about 2:30 this morning in San Diego County's inland valleys, mountains and deserts, though beach communities could also see rain and thunderstorms throughout the day and into the evening. More than an inch of rain in an hour, which translates into a heavy downpour, will be possible in some areas.
"The main focus for areas of heavy rainfall and flash flooding will be over inland areas. However, some of the rain is likely to affect areas closer to the coast as well," the NWS said. "In addition to the flash flood risk for inland areas, the heavy rain could produce flooding problems over urbanized land and debris flows below recent burn scars."
Radar loop shows strong thunderstorm developing over Mt. Laguna. pic.twitter.com/zCqSeFH9jS
— NWS San Diego (@NWSSanDiego) August 2, 2017
A flash flood watch means conditions may develop that lead to flash flooding, the weather agency said. The cities under the flood watch are El Cajon, La Mesa, Santee, Escondido, Poway, San Marcos, Julian and Pine Valley.
Wednesday's rain and stormy weather — courtesy of a monsoonal flow out of northern Mexico and Arizona — will maintain the streak of rare humid, sticky summer weather that produced record-breaking rainfall totals Tuesday.
Alpine received over 1.5 inches of rain, exceeding the prior Aug. 1 record of 0.11 inches recorded in 1992, the NWS said. Chula Vista, which received 0.07 inches of rain Tuesday, also surpassed the old Aug. 1 record of 0.03 logged in 1928.
Vista, meanwhile, matched its modest prior Aug. 1 record of 0.01, set in 1963.
Precipitable Water, a measure of total moisture, is at 2.06" at #SanDiego! Tropical moisture across #SoCal! #monsoon #cawx pic.twitter.com/bw0xlE8Jjq
— NWS San Diego (@NWSSanDiego) August 2, 2017
Other moisture totals included 0.42 in Skyline Ranch; 0.35 in Rainbow; 0.21 in Ramona; 0.2 in Flinn Springs; 0.12 in Barona; and 0.02 in La Mesa, the NWS reported.
The stormy weather also generated several hundred cloud-to-cloud and cloud-to-ground lightning strikes, along with wind gusts of up to 70 mph, meteorologists said.
