Severe Storms Possible Again Thursday

| April 21, 2020 @ 6:03 am

QUIET DAY AHEAD: Dry weather continues across Alabama today, despite a cold front passing through. No moisture means no rain, and not many clouds. The high will be in the 70s this afternoon. Fair weather continues tonight, and most of tomorrow will be dry although there should be a gradual increase in clouds.

MORE STRONG TO SEVERE STORMS THURSDAY: Another dynamic weather system will bring a severe weather threat to Alabama Thursday. Rain and storms should enter the state late tomorrow night, after midnight. These storms will be potentially strong to severe, but they will most likely be elevated. SPC has a low end severe weather risk (marginal to slight) over the western half of the state for the early morning activity.

Then, during the day Thursday, SPC has defined an “enhanced risk” (level 3/5) of severe thunderstorms for most of the state from Birmingham south and east. There is a “slight risk” (level 2/5) as far north as Vernon, Guntersville, and Fort Payne, and a “marginal risk” (level 1/5) up to the Tennessee state line.

Confidence is high in the threat of severe thunderstorms over the southern third of the state during the day Thursday, where the air will be very unstable and wind fields will be strong, The threat to North Alabama is more conditional; it all depends on how the morning round of storms plays out, the northward extent of the unstable air, and any small scale boundaries left over.

Storms over South Alabama Thursday will be capable of producing large hail, damaging winds, and a few tornadoes. A few strong (EF2 or higher) tornadoes can’t be ruled out. We will have much better clarity on timing this afternoon after the 12Z model set arrives. But it will be day when you want to hear all severe weather warnings (including severe thunderstorm warnings), and have your action plan ready if you are in a polygon.

FRIDAY AND THE WEEKEND: Friday will be a dry day with a partly sunny sky along with a high in the upper 70s. But another fast moving weather system will bring yet another round of rain and storms to the state late Friday night, mainly after midnight, into early Saturday morning. There will some unstable air involved, and these storms could possibly be strong to severe. We need to get past the Thursday event before we can really focus on this one. Then, the sky will clear late in the day Saturday, and Sunday will be quiet with ample sunshine along with a high in the low 70s.

NEXT WEEK: Monday and Tuesday look dry… then the next storm system arrives at some point in the Wednesday/Thursday time frame. See the Weather Xtreme video for maps, graphics, and more details.

STORM SURVEY RESULTS: NWS survey teams have determined that the damage in Chilton/Coosa/Tallapoosa counties early yesterday morning was caused by a wide swath of damaging straight line winds. Winds were in the 80-90 mph range in Chilton County, and county 70-80 mph range to the east over Coosa and Tallapoosa counties.

The storms were in a cool, stable airmass near the surface with temperatures in the low to mid 50s. With damage like this, we are often confronted with people insisting it was a tornado in places like Thorsby, Hanover, and Alexander City. Yes, there was rotation aloft, and you might have seen a funnel cloud, but the low level thermodynamic environment would not allow a tornado to drop. A stark reminder that damaging straight line winds can produce tornado-like damage, and are very dangerous and a threat to life. And, in the weather enterprise, we have to do a better job of reminding people to take severe thunderstorm warnings seriously.

ON THIS DATE IN 1967: Severe thunderstorms spawned 48 tornadoes in the Upper Midwest. Hardest hit was northern Illinois where sixteen tornadoes touched down during the afternoon and evening hours causing fifty million dollars damage. On that Friday afternoon, tornadoes struck Belvidere IL and the Chicago suburb of Oak Lawn, killing 58 persons.

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About the Author ()

James Spann is one of the most recognized and trusted television meteorologists in the industry. He holds the AMS CCM designation and television seals from the AMS and NWA. He is a past winner of the Broadcast Meteorologist of the Year from both professional organizations.

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