Drought-busting rain to be accompanied by severe weather risks in southern US

By Alex Sosnowski, AccuWeather senior meteorologist

April 17, 2018, 3:00:38 PM EDT

A storm is projected to take a tour of the southern United States with beneficial rain, localized flooding and isolated severe thunderstorms along the way spanning late this week to early next week.

The first signs of the storm will be spotty rain in central and Northern California and spotty snow over the Sierra Nevada and portions of the Great Basin in Nevada and Utah on Thursday.

Strong to locally severe storms are likely in eastern New Mexico on Thursday, western Texas on Friday, and perhaps central Texas on Saturday.

"While large hail, strong wind gusts, flash flooding and an isolated tornado are possible from the strongest storms, the odds are greatly against a significant outbreak of severe weather at this time," according to AccuWeather Storm Warning Meteorologist Richard Schraeger.

However, all it takes is one violent storm to threaten lives and/or for a storm to hit a populated area to cause great damage.

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By Friday, expect snow to break out across the southern Rockies, while rain develops and spreads over parts of the central and southern Plains.

Any non-flooding rainfall will be welcomed over the Southwest.

Nearly all of the region is abnormally dry, while some locations are experiencing extreme to exceptional drought, according to the United States Drought Monitor. In some cases there has not been significant rainfall since last autumn.

While much more rain than this single storm can deliver is needed to break the drought, enough rain may fall to bring a temporary end to the wildfire risk, provided lightning from thunderstorms does not start new fires.

An average of 0.50 to 1 inch of rain may fall from eastern New Mexico and southeastern Colorado to central Texas, central Oklahoma and southwestern Kansas from Friday to Saturday.

The storm is projected to take an east to southeast path across the South Central states this weekend and the Southeastern states early next week.

As the storm moves along and draws upon moisture from the Gulf of Mexico and later the Atlantic Ocean, rainfall amounts will increase.

Rainfall along the Interstate 10 and I-20 corridors may range between 2 and 4 inches with locally higher amounts. Any persistent downpours can lead to urban flooding.

The storm's swift forward speed should be enough to avoid major river flooding even though the ground is fairly moist over the lower Mississippi Valley.

How far north rain from the storm travels will depend on the exact storm track. It is likely for there to be a sharp northern edge to the rain. It is possible the rain barely reaches I-40 in Tennessee and stays south of I-40 North Carolina.

"It is possible conditions become favorable for severe thunderstorms along the I-10 corridor of the Gulf Coast, which includes the chance of a few tornadoes during the latter part of the weekend," Schraeger said.

The speed at which the storm exits the southern Atlantic coast during early next week is questionable at this point.

One scenario brings a few days of showers and thunderstorms from Florida to the North Carolina Outer Banks. Another scenario brings 12-36 hours of the same before dry air sweeps in from the north.

Many areas from Florida to North Carolina are also abnormally dry and could benefit from several rounds of showers and non-severe thunderstorms.

With the storm taking a track across the Deep South, many days of dry weather and warm sunshine are likely across the storm- and winter-weather weary Midwest and Northeast this weekend into next week.