On April 5th, 2017 two rounds of convection passed through the region leading to thunderstorm activity. This weather event led to heavy rain, gusty winds, and large hail! The first batch of rainfall came as a warm front pushed northward during the morning hours. Near and around this front there was an increase in moisture and warm air. The high dew point values and warm temperatures created an unstable airmass, helping enhance the threat of storms for the afternoon. Although the area didn’t experience severe weather during the morning hours, it did have a large impact on the afternoon threat.
By early afternoon, dry air moved into the region leading to breaks in cloud cover. The breaks in clouds led to an abundance of sunshine which in turn increased the instability for storms to tap into. Severe storms this day were more discrete in coverage than widespread. Strong shear and better instability combined with forcing ahead of the dry-line helped break the capping, allowing for deep convection. These discrete supercells moved northeastward late in the afternoon and evening, mainly in the eastern half of the area! Large hail was reported across DeKalb, Jackson, Madison, and Marshall counties in Alabama. Hail ranged from 0.50 to almost 2 inches in diameter.
Along with the large hail that was produced by the storms, winds were gusty at times. This was thanks to a tightly compacted pressure gradient, leading to strong gradient winds. Wind gusts ranged from 40 to 45 mph, prompting a Wind Advisory to be issued for the area that day. The strongest wind gust was measured at the Huntsville International Airport where the wind gust was 48 mph.
For more information on this event, head over to the National Weather Service in Huntsville’s page.