The atmosphere over the Deep South is primed for a third straight day of intense, long-track tornadoes over pretty much the same areas that were slammed by severe weather yesterday. The worst storms will start to form over Mississippi early this afternoon, and begin to move eastward as they organize later this afternoon.
Where is the outbreak expected?
As with the storms yesterday, the worst weather will begin to form over western Mississippi where skies are relatively clear and daytime heating is maximized. The Storm Prediction Center highlighted the areas shaded in red on the above map as at greatest risk for seeing violent, long-track tornadoes today. This includes Jackson, Meridian, Starkville, and Columbus in Mississippi, as well as Mobile, Tuscaloosa, and Birmingham in Alabama.
The greatest tornado threat exists about 75 miles on either side of the Mississippi/Alabama border. Much of Alabama and Georgia will face a damaging wind threat later tonight as the storms merge into a line, much as they did last night. The storms were ferocious when they hit Mobile — we got almost 4" of rain in less than an hour.
When will it start?
Those clouds over southern and eastern Alabama are posing a problem right now, which is why the storms will begin to fire in Mississippi where skies are clear and the air is having a much easier time becoming unstable. By the early afternoon hours (1-2PM), there will be enough instability and wind shear over Mississippi to sustain supercell thunderstorms capable of producing tornadoes, very large hail, and damaging winds.
The Storm Prediction Center announced at 1202PM CDT that they would have to issue a tornado watch for much of Mississippi and parts of bordering Louisiana by 100-200PM CDT.
The storms will move east into Alabama later in the afternoon, and eventually congeal into a squall line this evening and later tonight as it moves through eastern Alabama and into Georgia. Once the storms form into a line, the threat will transition over to damaging winds rather than tornadoes, though the threat for tornadoes can't be ruled out.
What are the chances?
The area most at risk across Mississippi and Alabama have a 15% higher-than-normal chance of seeing at least one major tornado within 25 miles of any point within the shaded area. Since this refers to the chance of seeing a tornado compared to normal, the 10% (yellow) and 15% (red) areas are extremely high. Usually, a 5% probability (brown) warrants concern.
The black hatching across the 15% zone means that the tornadoes that form in the area could be intense, long-lived tornadoes like the ones we saw on Sunday and Monday.
What can I do to protect myself?
I've copied this from my severe weather post yesterday, because even though the atmospheric conditions have changed and shifted, safety tips stay the same:
"If you live in the risk area, the best thing you can do to protect yourself is to have a plan in case you go under a tornado watch or tornado warning.
When you're at home, work, or school, take a look around and scout out the safest place to take shelter in case a tornado warning is issued and you need to get to safety. The best place to be in a tornado is underground either in a storm shelter or basement, but many buildings don't have them. If you can't get underground, you'' want to find a small, interior room that has as many walls between you and the outside as possible. Closets and bathrooms are usually the best, especially in townhouses, offices, and schools.
If you live in an apartment building and you're not on the ground floor, you need to make some friends downstairs and go to one of their apartments if a tornado threatens. Tornadoes can shear the top one or two floors off an apartment building with relative ease, so it is not a place you want to take shelter.
Mobile homes are the worst place to be in any type of severe weather, let alone during a tornado. Mobile homes are not built to withstand winds much higher than 60 MPH, and oftentimes they start seeing damage well before that. If you live in a mobile home and tornadoes threaten your area, leave and find a sturdy building. Go to a bank or local school — they will let you in to take shelter.
Once you find your safe place, make sure it's stocked up with supplies to help you survive the tornado and seek/administer help once it passes."
One more thing to add that I didn't yesterday: if you have a bicycle or motorcycle helmet, wear it and make your kids wear theirs when you're taking cover from a possible tornado. The number one cause of death in a tornado is a head injury, so wearing a helmet may look silly but it could keep you alive.
(This section is also a copy/paste from yesterday).
- The Storm Prediction Center is the official agency in charge of predicting severe thunderstorms in the United States.
- The National Weather Service issues local forecasts, as well as severe thunderstorm/tornado warnings across the U.S.
- Wunderground provides excellent weather radar imagery — click on the + closest to your location.
- NASA's website provides excellent satellite imagery from the GOES weather satellites.
- Dr. Greg Forbes of The Weather Channel is a world-class meteorologist who developed the accurate TOR:CON index that evaluates the threat for tornadoes on a 0-10 scale. Dr. Forbes' TOR:CON forecasts are found on weather.com.
[Images via SPC and NASA]