For the third time in less than a week, a winter storm has moved in over San Diego County. The system will bring heavy rain overnight and fresh snow in the mountains – but a lot less wind than last time.
Rain was expected to drench the northwestern part of the county first at around 10:30 p.m. The rest of the region will get its fill as an atmospheric river sweeps across the county to the east.
NBC 7 Meteorologist Dagmar Midcap said Thursday night's storm will be milder than the system that thrashed the county on Monday, though there will be heavy rains and heavy rainfall rates.
Between .2 and .5 inches of rain per hour could fall across the county, and warmer temperatures will invite a higher likelihood of thunderstorms after 10 p.m., Midcap said. There will be 6 to 12 inches of fresh snow at altitudes above 6,000 feet.
The heavy rainfall, though, could lead to localized flooding Thursday night and overnight, according to Meteorologist Sheena Parveen.
Flash Flood Watch
To that end, the National Weather Service has issued a flash food watch for San Diego’s coast, inland valleys and mountains that will be in effect from 7 p.m. Thursday through 4 p.m. Friday.
The NWS said the heaviest of the rainfall is expected to hit before midnight and last through 6 a.m. Friday. Scattered showers will linger throughout Friday. Rainfall rates, according to the NWS, are expected to be about a half-inch per hour.
“Rainfall amounts are impressive with all areas over and to the west of the mountains seeing anywhere from 1.5 inches near the coast to nearly 3 inches on the coastal slopes of the mountains in just 24 hours,” Midcap added.
Verena Castaneda spent Thursday afternoon with her niece filling sandbags in Bonita hoping to prevent a repeat of what happened earlier this week.
"The last storm that came through a couple days ago, it ended up getting water inside our back room," Castaneda said.
Bonita couple Candice and Jericho Canlas filled a few bags, too, knowing what heavy rains could do from personal experience.
"Last year water came through our garage, so now we are getting ready this time to put some sandbags up front so water won’t come through," Candice Canlas said.
Cal Fire tweeted that fire stations in areas like Julian, Mount Laguna, Ramona, Campo and more may have free sand and/or bags available for locals to pick up ahead of the storm. Locals should call the select fire stations ahead of time to make sure the sand, bags, or both are still available.
Flash flooding can lead to mud and rockslides, especially in recent burn scar areas, Midcap said.
“Stay away or be swept away,” the NWS’ flash flood watch warned. “Know your escape routes. Be reay to act immediately and heed all evacuation orders.”
What About Snow? A Winter Weather Advisory
Parveen said the rainfall and wintry mix in the mountains (rain and snow) will continue into Friday.
Midcap said some snow is expected at higher elevations of about 5,000 feet and above in San Diego’s mountains but added, “This is a much milder storm system – temperature-wise – than the last two systems.”
For San Diego’s mountains above 5,000 feet, the NWS has issued a winter weather advisory, in effect from 8 a.m. to 6 p.m. Friday. About 3 to 6 inches of snow are expected. Midcap said 6 to 12 inches could be seen above 6,000 feet.
Travel on snow-covered, slick mountain roads will be challenging, with reduced visibility, so the NWS said extreme caution is necessary if driving in those impacted areas.
Parveen and Midcap said the rain will begin to dry out late Friday – just in time for a dry weekend. Temps will stay cool and mild Saturday and Sunday.
For the latest NBC 7 First Alert Forecast updates, click here.
And, by the way, NBC's StormRanger is standing by in Southern California's inland empire, ready to track the storm as it makes its way into our region, giving us the most up to date information as we continue to track the winter weather.