Confidence growing in potential for severe weather

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Here's a timeline of potential severe weather starting Sunday into Tuesday. Remember, since we're still several days out, the timing could change, so keep up to date on forecasts. (Storm Prediction Center)
Leigh Morgan By Leigh Morgan
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on April 26, 2014 at 8:15 AM, updated April 27, 2014 at 3:17 PM

It's looking more likely that severe weather will affect much of the state starting possibly early Monday and stretching into Tuesday and Wednesday. The National Weather Service in Birmingham called it a "significant" risk in a weather briefing Saturday morning.

Multiple rounds of severe weather will be possible across the area with tornadoes, damaging straight-line winds, hail and flooding possible, forecasters say.

Be prepared for a lot of heavy rain.

"Flooding will be a high threat," the NWS notes. "… these storms should be proficient rainfall producers and will cause flooding issues."

Here's what forecasters are thinking right now (and remember this will evolve as we get closer to the event): There's a big, powerful, slow-moving upper-level storm system taking shape across the Plains states. That system is forecast to spawn storms across that region on Sunday, and a moderate risk of severe weather is in effect for that area. 

As that system advances our way, early Monday, computer models suggest a mesoscale convective system, or MCS, will develop and move into the state from the west. An MCS is a bigger than normal batch of storms that hold together for several hours or hundreds of miles. It could be in a cluster or more linear, like a squall line.

The MCS is supposed to weaken as it nears the state and moves away from the storm system's main energy, but a few severe storms are not out of the question, NWS meteorologist Aaron Gleason said in a briefing Saturday. The best chance of strong storms will be west of Interstate 65 and north of I-20, the NWS notes.

Later Monday night and into Tuesday comes round two. 

The Storm Prediction Center has placed a sliver of extreme northwest Alabama, much of northern Mississippi and parts of western Tennessee under a moderate risk for severe weather on Monday, and a slight risk area covers all but the southeastern portion of Alabama. 

Another batch of storms is forecast make it into the state Monday evening, and they stand a better chance of maintaining their strength. Atmospheric conditions will be more favorable for storms to rotate, the NWS has noted.

Much of North and Central Alabama has a 30 percent chance of seeing severe weather within 25 miles of a point location, Gleason said. "This is a fairly high percentage even for spring in Alabama," he added.

Forecasters believe the greatest risk for Alabama will be in the northwest parts of the state.

"But we're still three days out, so the highest threat area could change," Gleason said.

Then comes a possible round three. The SPC has put most of the state under a risk of severe weather, but hasn't rated that risk yet because it's several days away. We should see our risk area better defined on Sunday.

"It's this third round we're most concerned about," Gleason said, because those storms will have the extra energy of the cold front fueling them. 

Remember the timing could change, but it appears Tuesday afternoon through Wednesday morning is the window -- the worst will be over when the cold front finally passes.