South Texas faces half a year’s worth of rain as rare severe storms threaten the Pacific Northwest

By Mary Gilbert, CNN Meteorologist

(CNN) — The Pacific Northwest is staring down a rare spring severe thunderstorm threat and Texas is preparing to see up to half a year’s worth of rain by the weekend as March continues its streak of unusually disruptive weather.

Damaging thunderstorms are highly unusual in the Pacific Northwest any time of year and Texas’ rain threat would be more at home during hurricane season than spring. But this month has already been marked by multiple storms that broke the status quo, whipping up violent thunderstorms, blizzards and choking dust across the country.

Here’s how the topsy-turvy weather will unfold this week:

Half a year’s worth of rain could fall in South Texas

Up to half a year’s worth of rain will drench parts of South Texas starting late Wednesday as a storm develops in northern Mexico and taps into plentiful Gulf moisture.

The heavy rain will become widespread Wednesday night and continue into Thursday. Rainfall rates could reach 2 to 3 inches per hour at times and send totals skyrocketing.

The gushing rainfall will bring some drought relief to the bone-dry region, but it will come at a price: flash flooding.

“Unfortunately this setup looks good enough to be a case where it’s beneficial rain initially, but then quickly overwhelms even the dry soil conditions,” the Weather Prediction Center warned.

A level 3 of 4 risk of flooding rain is in place Wednesday in South Texas – including Corpus Christi – and the same risk level is in place Thursday from Corpus Christi to just south of Houston along the state’s Gulf coast, according to the center.

Double-digit rainfall totals are likely and some of the hardest-hit areas could record more than a foot. These totals are quite rare for the state outside of hurricane season, which runs from June through November, and could be up to five times March averages.

Rainfall totals of 8 to 10 inches are likely in Corpus Christi from late Wednesday through Friday, but could approach 15 inches if the city is trapped under the heaviest rain. Corpus Christi has never had 8 inches or more of rain from a storm before June, according to a CNN analysis of NOAA data.

On average, just over 2 inches of rain fall in Corpus Christi in March, with about 30 inches over an entire year. That means the city could record half its annual rainfall in about 72 hours in the worst-case scenario.

South Texas will see some of these showers linger through Friday before the weekend largely dries out.

Pacific Northwest could be pummeled by egg-sized hail in rare spring thunderstorms

The Pacific Northwest isn’t a hotspot for damaging thunderstorms – especially in early spring – but that could change.

A level 2 of 5 risk of severe thunderstorms is in place Wednesday for parts of Washington and Oregon, including the cities of Seattle and Portland, according to the Storm Prediction Center.

Severe thunderstorms will rumble to life Wednesday afternoon in parts of western Oregon and push into western Washington a few hours later. These storms could deliver damaging wind gusts and even a brief tornado or two, but hail will be the greatest threat.

Large hail – from the size of quarters up to the size of chicken eggs – is possible, according to the SPC. It’s the first time on record the SPC has outlooked hail this large in Washington and Oregon, according to a CNN analysis of NOAA data.

Wednesday’s level 2 of 5 severe thunderstorm risk is the most substantial threat ever issued this early in the year in Washington state. Typically, a few severe thunderstorms roar through the Pacific Northwest later in the season and through the summer.

Damaging hail and severe thunderstorms are far more common in parts of the central and southern US in spring: Ping pong ball, golf ball and egg-sized hail pounded the Dallas area in Texas on Tuesday.

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CNN Meteorologist Brandon Miller contributed to this report.