Mesoscale Discussion Issued for Northern Half of North/Central Alabama

SUMMARY… A gradual increase in storm coverage is expected over the next few hours. A couple of the stronger storms may produce marginally severe hail and perhaps a damaging gust or two. Severe coverage however, is expected to be somewhat limited by relatively marginal instability, though convective coverage will be monitored for the need of a Severe Thunderstorm Watch.

DISCUSSION… The eastward progression of a surface low, along with continued heating, are expected to contribute enough low-level lift to support increasing convective coverage over the next few hours across portions of central and northern AL into far southern middle TN. Clearing skies are allowing for some modification of the boundary-layer, while the westward approach of a 7-7.5 C/km mid-level lapse rate plume will encourage some airmass destabilization while overspreading the modifying boundary layer. However, given the amount of overturning from earlier convection, the atmosphere is expected to only become marginally unstable, with 500-1000 J/kg MLCAPE being common (with perhaps localized areas of 1000-1500 J/kg possible). Nonetheless, 50-70 kts of effective bulk shear and the near 7.5 C/km mid-level lapse rates will promote at least marginally severe hail with the more intense storms. A couple damaging gusts may also occur with the stronger downdrafts.

While convective coverage is expected to increase through the afternoon, severe coverage may be on the more sparse end, though a localized cluster of hail/damaging gust instances cannot be completely ruled out. As such, conditions will be monitored for the need of a Severe Thunderstorm Watch should a localized swath of severe hail/winds become evident in future observations/guidance trends.

Category: Alabama's Weather, ALL POSTS, Severe Weather