NSSL WRF output for 4/2/09 potential outbreak

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!

One thought on “NSSL WRF output for 4/2/09 potential outbreak

  1. Wow, that’s a really detailed and fantastic post. I had seen for the first time, really, that there were some significant helicity values/etc. from Scott’s “unique products” for the area. Guess we’ll have to wait and see what happens!

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