Flooding coming to Southern California

AccuWeather

In today's Forecast Feed, AccuWeather's Bernie Rayno takes a look at a storm that could bring flooding to California.

Transcript

00:00Well, you ever hear that song, it never rains in Southern California, it pours?

00:06Well, that's what's going to be happening here as we get into the latter half of this week,

00:10and that's the focus of the feed here today.

00:12I think there's going to be flooding in Southern California with the rain that we're going to see.

00:17And I learned this years ago from one of the AccuWeather icons, Dr. Joe Sobel.

00:23He always told me, listen, it's hard to get the jet stream far enough south to get rain in California,

00:29but when it happens, it almost always overachieves the rainfall because of the topography.

00:34I'll show you why here in a second.

00:36I want to show you, let's not bury the lead, let's get right into it.

00:39Listen, there's going to be some rain Thursday night into Friday,

00:42but the time frame where I'm afraid we're going to be looking at heavy rain is going to be Friday night into Saturday.

00:48What are we worried about? Flash flooding.

00:50I think that is a given in California.

00:53I also believe because of the terrain and the mountains and the recent fires that have burned in the last year,

01:00there's going to be some debris flows and problems in the burn scar areas.

01:05Now, here's the dirty truth, unfortunately, in California.

01:09Short-term pain with these rain events and flooding.

01:13Almost every time it rains heavily in Southern California,

01:17you're going to get flooding and you're going to have problems near the burn scar areas with fires.

01:21But the good news is this is the way you keep drought away from Southern California.

01:27In fact, of course, all of California, while there's pockets of drought in California right now,

01:31all of the reservoirs, and I mean all of them, especially the two big ones,

01:36which are the Shasta Reservoir and also Oroville Reservoir,

01:42are loaded to capacity from the rain and snow that we've seen over the last couple of days.

01:47Now, let me show you the ingredients for what is coming in the California.

01:51I'm very impressed looking at the satellite here.

01:54Look what's going on.

01:55You've got the upper low here, right?

01:57You've got a band of Pacific moisture here, but look what's going on here.

02:02Look at all of that tropical moisture coming in from the Eastern Pacific.

02:06I have it labeled here.

02:08I'm going to zoom on out a little bit here just to show you, right,

02:11how far south this moisture train goes.

02:14I wouldn't say here's the Hawaiian Islands, but you can trace this moisture pretty far south of Hawaii.

02:22So this is a true surge of tropical moisture coming northward.

02:27So it is loaded to bear right now.

02:30So you've got the moisture and you have what I call the dynamics with the upper low right here.

02:36Okay.

02:36So I'm going to show you the modeling here as we go forward,

02:40and I want to show you what we're looking at here.

02:43So this is this evening, and what we're looking at here, here's your upper low.

02:47You have the American model.

02:49This is European.

02:50This is the American model.

02:51I want to take you to Friday morning.

02:53Look what's going on here.

02:54The dip in the jet stream splits, as I mentioned.

02:58So let's go back into here.

02:59You've got Thursday evening, you've got one elongated area of moisture, right?

03:05Look at all the reds.

03:06That's showing you you have a lot of energy.

03:08By Friday morning, you see what's going on here?

03:10Let me go forward right here.

03:12You've got a piece here.

03:14This will go across northern California.

03:16So this is what's going to give central and northern California your rainfall.

03:20It's going to be a soaking rain.

03:21No doubt about it.

03:22You're going to get probably about one to three inches of rain throughout the entire area.

03:26But you see what's going on?

03:28This upper low kind of breaks off.

03:30You see that?

03:30Let me play it forward and I'll start.

03:32Let me go back to Wednesday evening and we'll play it through and you can see it.

03:37See how that goes?

03:37South Friday morning.

03:38Then watch happen Saturday morning.

03:40Stop Saturday morning.

03:42You see what goes on?

03:43You have this upper low now off the southern California coast.

03:47Let me zoom in a little bit here.

03:49So this is what it looks like.

03:51Southern California coast Saturday morning.

03:53You've got that upper low and you've got this perfect flow.

03:56Look at this.

03:57Saturday afternoon, Saturday night.

03:59You see the upper low?

04:00Where's it coming into?

04:01Right across Los Angeles and Ventura County.

04:04So what you're doing is you're taking all that tropical moisture and you're ramming it northward

04:08into California.

04:11And don't forget, in California, southern California, you're going to be helped by the terrain,

04:18the mountains.

04:18But look at all of this energy coming in.

04:21Let me go back to the big map here.

04:23You can see it.

04:23Look at all of this right in here.

04:26Look at that coming in the southern California Saturday, Saturday night.

04:30Now, I want to show you the topography of the west.

04:33Let's zoom in the California.

04:35Look at these and then I'll give you your bearings here.

04:38This is Ventura County, Los Angeles County, Orange County, San Diego County.

04:44Note the mountain ranges in here.

04:47The Santa Monica Mountains, the San Gabriel Mountains, the San Bernardino Mountains.

04:51And they all have one thing in common.

04:53When you look at them, they face to the west-southwest.

04:58So think what's going on.

05:00You've got all of this moisture coming in from the Pacific and its tropical moisture.

05:06And it's called what we call an upslope flow, right?

05:10An upslope flow where you bring the Pacific moisture in.

05:14You have a lot of energy to begin with.

05:15And then it's forced to rise.

05:18So the air cools.

05:20It condenses.

05:21You've got more upward motion.

05:23And that is going to cause extensive amounts of heavy rain, I'm afraid.

05:30Now, I want to show you the rainfall map here.

05:33Again, these models are what you can use on Yakima, the pro site here.

05:37This is the total amount of rainfall here.

05:39I'm going to go to Monday morning just to be on the safe side.

05:42Make sure we capture it all.

05:44Let me show you what this looks like.

05:46Look at this rainfall projected here.

05:48This is Los Angeles County.

05:50This is Los Angeles County, Orange County, San Diego County.

05:55I mean, you're looking conservatively at two to four inches of rain across San Diego and the southern and the Los Angeles Basin.

06:05Two to four inches of rain.

06:06Now, for you that live in the northeast, that doesn't sound like much.

06:09But take a look at this.

06:11This is the rainfall we see in California during the year.

06:14They average about 12 and a half inches of rain during the winter months, October, November, December, into March.

06:22About 12 and a half.

06:23You may get four to five inches of rain just with this storm from Thursday night through Sunday.

06:30And if you think about it, that covers all of the average rainfall for October, November, December.

06:35And it's about 30 to 40 percent of the entire rainfall during the winter.

06:42Good news.

06:44It keeps the drought at bay.

06:45The bad news.

06:46I'm telling you.

06:47Flooding is on the way.

06:48And that's the feed.

06:49Flooding is on the way.

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