Tornadoes and very large hail possible near Dallas and Fort Worth, while storms may also affect Phoenix and Nashville

Rotating supercell thunderstorms with damaging wind, large hail and tornadoes are possible over parts of Texas and Oklahoma on Wednesday afternoon and evening. Part of the Dallas-Fort Worth Metroplex and areas to the north and west are at risk, with conditions ripe for dangerous storms to develop.

Other pockets of severe thunderstorms with an attendant tornado risk are possible in parts of the Desert Southwest and Tennessee Valley.

Wednesday marks the first of several potential severe weather days, with strong to severe thunderstorms, and possible tornadoes, predicted across the Mississippi Valley on Thursday.

As we move into the nation's peak severe weather season during April and May, it is extremely important to monitor forecasts and have a severe weather plan ready to be activated at a moment's notice.

Southern Plains

Timing and hazards

The most dangerous thunderstorms of the day are likely to form by 6 or 7 p.m. in Central Texas. Initial storms will probably be supercells, or individual storms that rotate. A few storms may produce tornadoes, hail as large as baseballs, and destructive straight-line winds.

These storms will continue into the evening, lasting perhaps until midnight as they move into Oklahoma. It is especially worth mentioning that there will be a risk of nighttime tornadoes, which are most deadly.

[Hail, not tornadoes, is most expensive severe thunderstorm hazard in Texas]

Then a few additional thunderstorms may form a line that moves through the entire Dallas-Forth Worth Metroplex in the wee hours of Thursday morning. That line could be severe, with wind damaging gusts and isolated tornadoes possible.

The storms will produce heavy downpours and potential flash flooding. A flash flood watch is in effect for the Metroplex, where 3 to 5 inches of rain in the past several days have already left saturated soils.

Areas impacted

Not everyone will be affected by severe storms around the Southern Plains; many areas are likely to be missed due to the scattered nature of the first round of storms. But there exists a risk for significant severe weather Wednesday night, including an isolated strong tornado.

Areas most at risk in the Southern Plains include communities north of Interstate 20 to the Red River, perhaps into extreme southern and southwestern Oklahoma. Fort Worth, Abilene, Wichita Falls and Denton are all in the area specifically mentioned by the Storm Prediction Center as having the greatest tornado risk.

This includes Throckmorton, Tex., where several minor tornadoes touched down in the vicinity on Tuesday afternoon.

Much of southwestern Oklahoma and Central Texas is under an enhanced risk of severe weather. That's a level 3 out of 5.

Right now, Dallas looks to lie on the periphery of the greatest risk corridor, with storms most likely to the north and west. That could change in later forecasts, however, so residents of the city are urged to stay tuned to later forecasts.

Action items

If you live in the risk area, it is especially important to remain up to date with the forecast. Be aware that a threat could exist overnight.

Charge cellphones and remember to turn "do not disturb" mode off and enable the wireless emergency alerts function. It will alert you if a tornado warning or higher-end flash flood warning is issued.

Otherwise, remember to identify a shelter location that can quickly be accessed if needed. Severe weather radios are also ideal to have during this and every event this severe weather season.

Tennessee Valley, including Nashville

Timing and hazards

A very low-end severe weather risk (level 1 out of 5) is possible for parts of Middle Tennessee and Central Kentucky.

Clouds have limited the amount of warm sunshine in the area, cutting back on the overall severe weather risk. However, the Storm Prediction Center has maintained a marginal risk for severe weather, as strong winds in the upper atmosphere mean any isolated storms that do form could rotate.

A few isolated showers or storms could develop with a southeastward-sagging front this evening and for a few hours after dark. Damaging winds and a very marginal risk of a tornado are of concern if any storms do form.

Arizona, including Phoenix

Timing and hazards

A marginal (level 1 out of 5) risk of severe weather also includes southern Arizona, including Phoenix.

Showers and thunderstorms will become scattered to numerous during the late afternoon and evening hours, capable of producing isolated damaging winds or severe hail, up to quarter size. It's unlikely that storms will become much stronger than that.

Heavy downpours are possible as well. "[We] would not be surprised to see localized [rainfall] rates up to 0.75-1.00 inches with storms this afternoon," the National Weather Service in Phoenix wrote.

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