Today’s 4-km NSSL WRF run suggests a supercell convective mode across Mississippi and Alabama between 18z 2 APR and 00z 3 APR, followed by a severe squall line in the eastern half of Alabama after 00z. The NSSL WRF output hints at a “storm of the day” long-track supercell to form in SW MS near the Louisiana border, and then track continuously for several hours into central AL between BHM and MGM. The model also generates a maximum in the most unstable CAPE (MUCAPE) across central MS into northern AL by late afternoon. Follow these links to view the full-domain NSSL WRF output, and the daily SPC zoom domain for more times and graphics.
Here are some details and accompanying graphics:
- MUCAPE exceeding 1500 J/kg is predicted across north-central AL by 21z (panel a).
- A long-track supercell begins by 18z (panel b), tracks to SW AL by 21z (panel c), then to central AL by 23z (panel d) before dissipating thereafter (not shown).
- The maximum hourly updraft helicity at 23z confirms a significant rotating updraft in the predicted “storm of the day” over central AL (panel e).
- Finally, panel f shows the convective mode evolving into an intense squall line over eastern AL by 03z 3 April (panel f). An examination of the maximum hourly updraft helicity suggests that supercells may be embedded within the line (panel g).
We’ll see how well this complex forecast verifies!