Here’s the science behind the severe weather expected this weekend

A wave of storms is expected across the region over the next several days, and the first sign will be stifling humidity that blankets the area Thursday.

Brett Rossio, a meteorologist with AccuWeather Inc., The World-Herald’s private weather consultant, said the humidity will arrive thanks to the warm, moist air the storm pulls northward from the Gulf of Mexico.

And in the classic fashion, the clash between that warm, moist air and a cold front descending from the north will set the spark for successive waves of severe weather.

Damaging hail, powerful winds, heavy rain and even tornadoes are all possible. The threat begins Thursday afternoon and lasts through the weekend. Each round of storms will alter the atmosphere and affect how the subsequent set of storms plays out, said Rossio and others. For that reason, among others, people should monitor forecasts, especially anyone with outdoor plans.

The forecast for the next four days, which could change, depending on how the atmospheric dominoes fall:

Today

Sunny, with a high near 92. South southwest wind 9 to 15 mph, with gusts as high as 22 mph.

Tonight

A 20 percent chance of showers and thunderstorms after 1am. Partly cloudy, with a low around 66. South wind 10 to 14 mph, with gusts as high as 20 mph.

Friday

Partly sunny, with a high near 87. Breezy, with a south wind 11 to 21 mph, with gusts as high as 29 mph.

Friday Night

A 50 percent chance of showers and thunderstorms, mainly after 1am. Increasing clouds, with a low around 67. Breezy, with a south wind 13 to 22 mph, with gusts as high as 28 mph. New rainfall amounts between a tenth and quarter of an inch, except higher amounts possible in thunderstorms.

Saturday

A 50 percent chance of showers and thunderstorms. Mostly cloudy, with a high near 79. South southwest wind 13 to 15 mph, with gusts as high as 23 mph. New rainfall amounts between a tenth and quarter of an inch, except higher amounts possible in thunderstorms.

Saturday Night

Showers likely and possibly a thunderstorm. Cloudy, with a low around 53. Chance of precipitation is 60%. New rainfall amounts between a half and three quarters of an inch possible.

Sunday

A 30 percent chance of showers before 1pm. Mostly cloudy, with a high near 64. Breezy.

Sunday Night

Partly cloudy, with a low around 45.

Monday

A slight chance of showers. Partly sunny, with a high near 64.

Solid advice vs. myths: Here’s what you need to know when tornadoes, severe storms threaten

When a tornado strikes, the greatest danger is flying or falling debris.

That’s why the National Weather Service says it is important to stay low and pay attention to where you seek shelter so you minimize your chances of being crushed. Here is more advice from the weather service to help keep you safe:

Monitor forecasts: On days when conditions are ripe for a tornado to form, the weather service will issue a tornado watch. On days like that, monitor evolving forecasts, pay attention to your surroundings and know where you’ll seek safety on short notice. The weather service will issue a tornado warning if its radar detects rotation or it is notified of a confirmed sighting.

Ahead of the storm: Have a family plan and practice a family tornado drill. Be sure your cellphone batteries are charged. Have safety supplies in place (battery-operated radio, shoes, bike helmet, padding, etc.). Have a predetermined place to meet after a disaster.

React according to where you are

Mobile home:

  • Get out, says the weather service. If you have time, run to a tornado shelter or permanent building. If one isn’t available, go outside and lie flat on low ground and protect your head. Get away from trees and cars, which can land on top of you.
  • In general, meteorologists say, even your parked car outside your mobile home is safer than the home itself. If you choose that option, get in the car, put on your seat belt and lie down so that your body is below the windows.
  • Best plan: During peak periods of danger, plan ahead so that you are away from your mobile home and instead are somewhere with sturdy shelter.

Home with a basement:

  • Go downstairs and huddle under sturdy protection, like a work bench, table or stair steps. Stay away from windows. Avoid areas beneath heavy appliances or furniture — refrigerators, stoves — that could crash through the floor and crush you.
  • Have extra protection on hand: A mattress to pull over you, shoes so you can walk out over glass and other sharp objects, a bike helmet to protect your head.
  • Have a transistor or weather radio or cellphone to monitor conditions.

Home without a basement:

  • Go a small, interior room on the lowest floor, like a bathroom, closet, stairwell or hallway. Stay away from windows. Crouch as low as possible, face down, with hands over your head. Cover yourself with a thick padding — blankets, mattress, couch cushions. Wear shoes, and keep a cellphone or radio handy.

Office building:

  • Seek a windowless area in the center of building, away from glass and on the lowest floor possible. Stay off elevators. Crouch down and cover your head.

Shopping mall, big box store:

  • Keep calm and watch out for others as you seek an interior restroom, storage room or small enclosed area away from windows. Crouch low, cover your head. Follow the directions of a store manager or, if you have a favorite store, learn the locations of the restrooms and storerooms.

Vehicle:

  • Cars and other vehicles are not safe. Do your best to pull off the road and take shelter in a permanent building during powerful storms.
  • If you are in open country and have time to drive out of the tornado’s path, here’s how to do so: Watch the tornado for a few seconds, comparing it to a fixed object such as a tree or highway sign. If the tornado is moving to your right or left, it is not moving toward you. Escape by driving at right angles to its track — to your right if it is moving left or to your left if it is moving right. If the tornado appears fixed and isn’t moving left or right, it is likely moving toward you.
  • Get out of the way and seek shelter away from your car. If the tornado hits you while you’re in your car, be sure your seat belt is fastened and lie low, below your windows.

After a tornado: Stay away from power lines and puddles with wires in them. Do not use matches or lighters in case of leaking natural gas or fuel tanks. Stay out of heavily damaged buildings. Render aid, stay together.

Tornado myths:

  • Opening windows will equalize pressure and protect your house. No, this will just delay you from getting to shelter and increase your risk, especially to flying glass.
  • A particular corner of the basement is safest. No, if your house shifts and the walls cave in, being in a corner or near an outer wall could be dangerous.
  • Tornadoes will avoid a lake, river, a certain valley or a mountain.Nope.
  • Parking under an Interstate overpass is the safest place to ride out a tornado. No! Seek shelter in a permanent building.
Share: