So, after we have had a couple of weeks without the potential for severe weather during the peak of severe weather season in Central Alabama, there will be a threat for strong to severe storms coming up for a good portion of the morning and afternoon hours on Saturday (April 24th). At this point, it could be a two-round event as we’ll have a warm front move northward through the area during the morning hours before a cold front sweeps through during the afternoon and into the early evening hours.
• Timing: 6 am to 11 am on Saturday morning.
• Threats: a few tornadoes, damaging winds up to 60 mph, and up to quarter-sized hail.
• Threat Area: along and south of a line from Reform to Gardendale to Jacksonville.
A warm front will be moving northward through the morning hours across Central Alabama, and during that time, a short wave will also move across the area that will provide the lift needed for the potential of stronger to severe storms. There will be a strong low-level jet in place with winds in the 60-70 knot range, providing plenty of shear. Add that with rapidly rising instability as the warm front continues its trek northward, and the ingredients will be in place for the potential for strong to severe storms.
The latest forecast sounding from the 12z NAM-12k model run for the Birmingham metropolitan area shows that 0-6 km shear will be just over 60 knots, surface-based instability will be right at 1,900 J/kg, and storm-relative helicity at the 0-3 km level will be around 270 m2/s2. All of this is to say that all modes of severe weather will be possible as the atmosphere will be unstable and the setup is there for robust rotating updrafts. The significant tornado parameter is at 3.5 in this sounding. Significant tornadoes are known to occur in readings over 1.0.
At this point, the Storm Prediction Center has all of Central Alabama south of a line from Reform to Gardendale to Jacksonville in a 15% chance for severe weather on their Day 4 Convective Outlook, which would equate to a level 2/5 Slight Risk for severe storms.
• Timing: 12 pm Saturday afternoon to 6 pm Saturday evening.
• Threats: damaging winds up to 60 mph, up to quarter-sized hail, localized flash flooding, and a brief spin-up tornado.
• Threat Area: all of Central Alabama.
After the short wave and the low level jet move east of the area by the late morning hours, there may be a potential lull in the action for a couple of hours before storms start forming along and just ahead of the cold front as it begins to move through the area. Instability will actually continue to rise ahead of the cold front and shear will increase, but we will be losing the helicity in the lower levels needed for the potential for tornadoes. However, we simply cannot rule out a brief spin-up tornado with this setup. The main threats will be for damaging wind gusts up to 60 MPH and large hail that could exceed quarter-size in diameter.
This activity will be scattered in nature, but any cells that do form will have plenty of moisture to work with. Some of the heavier thunderstorms could dump up to 2 to 3 inches of rain, which may lead to some localized flash flooding issues. The cold front will push east and southeastward through Central Alabama with the timing of severe weather threats to be from 12 pm to 6 pm from northwest to southeast across the area.
After the front passes your location, the threat for severe weather will be over and winds will be out of the northwest which will bring drier air into the area for Sunday.
Please share this with anyone who is planning on camping out or attending the race activities at Talladega Superspeedway on Saturday, as the facility lies within the severe threat area defined by the Storm Prediction Center. The good news is that this will all happen during the daytime, but the bad news is that it will more than likely bring delays to the ARCA Menards Series and Xfinity Series races.
You know the drill… have your severe weather safety plans, safety kits, and place of safety ready to go just in case your location goes under a warning. Have multiple ways to receive weather alerts, stay up-to-date with the latest weather update throughout the rest of the week, and be sure that your friends, family, neighbors, and co-workers know about the upcoming potential for severe weather.