Unfortunately, we’ll be needing to spend this Easter evening getting ready for a round of strong storms tomorrow morning. The severe weather threat for Monday is coming into focus, and there’s not been much change to the previous thinking: A line of strong to severe thunderstorms will push through the area during the morning hours. These thunderstorms will be moving into an atmosphere that is favorable for strong, damaging wind gusts (70 MPH possible, according to the National Weather Service), a few tornadoes (one or two of which could be fairly potent), and large hail.

Still some timing kinks to work out

According to its latest briefing package, the National Weather Service says the timeframe for severe weather is between 6am and noon across the county warning area, with an eye on impacts reaching the western edges of the Tri-County area between 9 and 11am, and then impacts in the Charleston metro area between 10am and noon.

This could yet be sped up, though, depending on what transpires to the west. There are, in fact, signs in some of the High-Resolution Rapid Refresh data that the line of storms could come through the metro area an hour or two ahead of this forecast, so be flexible and plan using the 6am-noon estimate until the finer details become clearer.

Ways this could be a little weaker

There are a couple other potential flies in the ointment as well. First, this forecast assumes rich moisture return ahead of it. If there is any disruption to the quality of that moisture return, it could disrupt the severe threat. This does not appear to be a likely scenario, though, as the orientation of the line and the location of the forcing mechanisms should keep areas to our south relatively clear.

The other thing to watch will be water temperatures around 70°. While perhaps not as disruptive to an advancing line of storms as water temperatures in the 50s, we cannot rule out some interference from the marine layer on helping to weaken this line. However, this may also end up being a moot point with such potent winds aloft and plentiful wind shear to keep thunderstorms rolling. Southwesterly trajectories also pose a problem for this kind of scenario as well.

Let’s hope we can get some weakening, but plan for that not to happen.

What to do tonight

• Bring in loose items. A Wind Advisory goes into effect at midnight, with 40-50 MPH gusts possible well ahead of thunderstorms as the low-level jet really ramps up. Loose items could become hazardous in strong winds, much less severe thunderstorm wind gusts.
• Prepare to allow extra time for essential travel Monday morning. Wind gusts could push 50 MPH on bridges. While bridges do not close, if the gusts become frequent, they may temporarily go unpatrolled. If you have no essential travel, stay home! If the storms don’t get you, COVID-19 just might.
• Review your severe weather safety plan. Where would you go in a tornado warning? Is your family on the same page about this? Remember, the safest place to be in a tornado warning is in an interior room of a site-built structure, away from windows, with as many walls between you and the outside as possible. An interior bathroom is particularly awesome for this as the plumbing can act as a roll cage. For those of you in apartment buildings, try to seek shelter in an interior stairwell on the lowest floor of the building.
• Make sure your weather alerting is working. Ensure your smartphone is set to receive Tornado Warnings via Wireless Emergency Alerts in your phone’s settings. If you have a NOAA Weather Radio, make sure it can tone alert you to warnings. And finally, install a local news weather app, which has free alerting for your specific location.

What to do tomorrow

• Expect a tornado watch early in the day. It could be issued before many of us even wake up. A watch is your signal to be on guard for threatening weather, and be ready to execute your severe weather plan.
• Stay close to reliable weather sources and make sure you can hear warnings. If a warning is issued, move immediately to your severe weather safe place. Do not try to visually confirm the tornado, as it could easily be rain-wrapped and these suckers are going to be moving fast. If you have bike helmets, bring ’em. Wear shoes in case you need to step out over debris, and hope you don’t really need any of these things.

With any luck, we should be done with these storms by early afternoon. The sun will indeed come back out, and temperatures will head into the low 80s as the cold front won’t quite have gotten through just yet.

I’ll be providing updates as needed throughout the event starting early tomorrow morning. I hope you’ll ride along.

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