Dangerous cross-country storm could cause floods in California, tornadoes in Mississippi and ...

AccuWeather

A massive storm moving across the U.S. from Wednesday to Sunday may have an extreme variety of impacts.

Transcript

00:00John, we're going to step into a really prolific rainmaker with some big-time snow in the mountains as well.

00:06We are. It's going to be the biggest storm of the year, the wet season so far across Southern California.

00:12So it's bringing needed rainfall. We've had such dry conditions in the short term there.

00:16But the problem is if the rain comes too fast, too furious, which we think it will,

00:21we're going to be dealing with some significant flash flooding concerns as well as mudslide and rockslide concerns.

00:27Look at that atmospheric river, that channel of high levels of atmospheric moisture directed right at the California coast,

00:33including the L.A. area where we had those recent devastating wildfires, and that is a big concern, Jeff.

00:40Absolutely, John. And, John, can you talk a little bit about what makes greater danger on the heels of a big wildfire,

00:46especially if you have people living down the hill near Altadena?

00:50Yeah, all that, there's no longer any vegetation and structures there, tragically.

00:56So what ends up happening is that water has nowhere else to go except run off.

01:01And the ground, that is what increases the risk for those mudslides and that quickly escalating flash flooding situation,

01:09which is why we're so concerned about that.

01:11And there's also going to be the threat for some thunderstorms here from the Bay Area southward into Southern California as well,

01:19which can produce damaging wind gusts and even a widely separated tornado as well.

01:24And with those thunderstorms, that's where the intense rain rates sometimes of perhaps one half inch to one inch per hour can occur,

01:32and that's when we're most concerned about the serious flash flooding.

01:35And, John, there are some benefits to this regarding water supply,

01:38maybe even extending the ski season deeper into the spring on the cold side up in elevation.

01:43Look at that, feet of snow here, especially above 6,000 feet elevation.

01:48Look for road closures, Interstate 80 near Donner Pass and surrounding areas, a big snowstorm on the way in the Sierra.

01:54And, John, unlike the previous two storms that we've had this week, this one is going to be a true coast-to-coast storm.

01:59This one's going all the way across the country, and unfortunately, it's going to bring a variety of problems with it.

02:05To the north, we're going to be dealing with snow and ice concerns from the Great Lakes into parts of the interior northeast.

02:11Even can start as a bit of snow and sleet in the big cities along the I-95 corridor, such as New York,

02:17where there can be a coating to an inch, maybe a few inches up toward Boston before it ends up going over to rain.

02:22And, Jeff, further south there toward the Gulf Coast, big concerns.

02:26This looks like a very concerning setup here during the day Saturday into Saturday night with a severe thunderstorm and tornado risk.

02:34And some of these areas around Mississippi will be at especially heightened concern here.

02:38A moderate risk, two out of four on the AccuWeather Threat Level Index.

02:41And, in fact, in full transparency, John, I'm going to remove the word isolated.

02:45I want to match our forecast team's map.

02:47We dropped the word isolated from the tornado forecast from yesterday to today.

02:51We did because we're concerned this is a setup where there could be a dozen or more tornadoes,

02:55a fairly widespread event here, and also that some of these tornadoes could be particularly strong,

03:02and they might be on the ground for more than just a few minutes.

03:05So, as we kind of wrap this whole thing up, big headlines here associated with this coast-to-coast storm.

03:10California headlines at the end of the workweek.

03:12Huge, big concerns there.

03:14But moving forward, as we wrap this up, John, what among these do you think will be most impactful?

03:19It's hard to really pick one.

03:20Yeah, I think they're all going to be notable.

03:22That heavy snow, as we mentioned, across the Midwest and northern New England,

03:25the severe weather risk in the southeast, and also the concerns,

03:29another very active storm track into the northwest with our next storm system.

03:33All of this is to say it's a great time to stay tuned with us frequently here.

03:36Check in back with us more often at AccuWeather on the AccuWeather network,

03:40on the AccuWeather.com website, and the AccuWeather app.

03:43All great resources as we navigate together a very challenging weather situation over the coming days.

03:49All right, there he is, AccuWeather Chief Meteorologist John Porter.

03:52Thanks again, John.

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