>>> San Diego has seen some light rain showers in the past week. Forecasters say a bigger storm is on its way. And atmospheric river is taking shape off the coast it is set to bring in a major storm from Santa Barbara all the way down to us in a couple of days. The storm poses a threat of flooding in some areas. The rain is badly needed, but will it be enough to get us near to our average rainfall for the year. Joining me is Alex tardy media and public information officer with the National Weather Service in San Diego. Alex, welcome back. First of all, one of the elements that need to combine two create what you Meteorologist call and atmospheric river. >> That is a great question. It sounds like a new term but in the research field we've been looking at atmospheric rivers for a long time, decades. We scald and pineapple expresses. Basically what it means and what the research has shown is to look for where your moisture is coming from. The recent storm you mentioned, the light showers, they were all coming from the northern Pacific even Alaska. What we talk about atmospheric river We know comes directly from the tropics, has a lot of wind with that and it was really fast. Those two ingredients based on research results and a lot of rain. And more than went -- what we expect and more in the mountain communities. >>> How is this form -- storm approaching? >> It is slow moving right now. That's what adds up to the rainfall totals. First in the Santa Barbara area, central California south-central California, and slowly as we get into Wednesday night, moving into San Diego County. It looks like down here we will not see much rain until Thursday and then Thursday evening. >>> Areas of Santa Barbara have been evacuated already. Is the risk of flooding that severe ? >> The rain is just moving to that area today. It is light. We expect it to pick up heavy in that area tonight. And continue through Wednesday night heavy at times. We are looking at rainfall totals everywhere in Santa Barbara area of 3 to 5 inches would locally over 10 inches. Right now, that target area for the 10 inches is too close to the burn scar area. That is why I think you are seeing the proactive actions. When it comes to this type of rainfall or any type of rainfall and burn scars, it is the rainfall intensity. The numbers don't matter as much. It is the intensity of the rain and how quick it comes down in a period of time. >>> When the storm arrives here, is this going to be a cold storm? Will it be a Wendy storm? What kind of storm is it going to be ? >> We seen a little bit of everything this March. We are still way below normal. We're still barely pushing three inches of rain in San Diego. We should be up around eight. This particular storm coming in is going to be a mild, warm tropical rain really high snow levels. Nothing in San Diego County. We will be lucky in big bear even gets an inch of snow at the end of the storm on Thursday night. We will see warm air, relatively humid, generally, most people in San Diego County will see a light steady rain on Thursday. Your heaviest rain will come down Thursday afternoon and Thursday night during the dark hours. We don't expect flooding right now in San Diego other than urban small stream type problems switch any city sees when they get a quick burst of rain. Our mountains could do well like Palomar Mountain could get several inches of rainfall when it's done. >>> You said we still have a five inch deficit in our rain totals for the year. How much do we expect from the storm ? >> We are 30 to 40% normal five inch deficit. We only expect a half an inch in downtown San Diego. We have a long ways to go. In our mountains, list look at Palomar Mountain for example, they have seen about 10 inches of rain this year. They are only about 40% of where they should be. Less than half the bucket is full. We are almost at the end of March. If they pick up 3 to 4 inches of rain, our deficits are barely breaking 50% of normal. So barely half-full even after the storm. We got a remember it was a record dry start to this wet season. Our deficits are just massive and hard to dig out of. >>> Looking ahead, we have seen a series of storms come to the County the last couple of weeks. Is that weather pattern holding or the breaking up four >> It looks like once this atmospheric river moves through the tropical moisture, it will start to break up and we will have longer dryer periods as we go into April. It does not mean the season is over with. But it is not very promising in terms of getting us anywhere close to normal. We would have to have flooding events like with this type of system to get anywhere close to normal. Statistically, the odds are about 2% through the rest of the spring that we would get back to normal. So 2%, if that is a workable number. >>> Not really. Once again, when can we expect the heaviest rain from the storm? >> It will be during the commute hour on Thursday. Probably Thursday afternoon and Thursday evening. That should be the heaviest for most of San Diego County. >>> I've been speaking with Alex tardy media and public information officer with the National Weather Service in San Diego. Thank you, ALEX. >> Thank you very much.
California authorities are urging people living in an area devastated by mudslides to evacuate ahead of a strong Pacific storm that forecasters say is likely to bring an extended period of rain and the threat of flooding and debris flows.
Santa Barbara County issued a mandatory evacuation order Monday affecting about 30,000 people, including the community of Montecito, where 21 people were killed by a massive mudslide in January.
The evacuation order said residents should be out of the areas affected by noon Tuesday.
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Residents won't be forcibly removed if they choose to stay but Sheriff Bill Brown urged them to prioritize their safety despite potential evacuation fatigue.
"We understand the process of evacuating is tiring and frustrating, and we know that it is an extraordinary hardship on everyone being asked to leave their homes or to close their businesses once again," he said at a news conference. "We know that it is disruptive, costly and inconvenient. Please know that we would not be making this decision without it being our belief that it is necessary to protect your safety."
Brown said county officials reached the decision because "there is enough rain on the way to trigger a potential debris flow that could threaten life and property."
"We have no choice really but to do this," he said. "It is simply not worth risking lives to avoid evacuations."
National Weather Service meteorologist Mark Jackson said the storm is likely to be the strongest so far this winter.
"There's a tremendous amount of moisture coming up out of the Pacific," he said, adding that the key to the storm will be its lengthy duration.
Preliminary rainfall estimates for the so-called atmospheric river range from 2-5 inches (5-13 centimeters) across coastal and valley areas and 4-6 inches (10-15 centimeters) on south- and southwest-facing foothills and mountains, forecasters said, adding that local amounts up to 10 inches (25 centimeters) can't be ruled out.
Where exactly the peak rainfall will occur was still uncertain, but meteorologists said it seemed likely it would be Santa Barbara County.
A stretch of the county's south coast was hit hard by a storm on Jan. 9, unleashing massive debris flows from scorched mountains above the community of Montecito. Hundreds of homes were damaged or destroyed, 21 people were killed and two still remain missing.
The storm was also expected to spread rain up the coast through the San Francisco Bay region and eastward to the Sierra Nevada, where a flash flood watch will go into effect Wednesday from about Yosemite southward.
