Checklist for Tornadic Outbreaks in the Southeast
Synoptic Scale, 36 hours
  1. Midwest high amplitude trough, approaching cold front
  2. Juxtaposed polar and subtropical jets
    1. Supergeostrophic subtropical jet exit region
    2. Subgeostrophic polar jet entrance region
  3. Cold front aloft in vicinity of juxtaposed jets
  4. Confluent low level jet
Synoptic to Subsynoptic Scale, 12-36 hours
  1. Warm (Temp @ 850mb >20 degrees C), dry (T-Td @ 850mb >10 degrees C) air near south Texas
  2. Surface thermal-moisture boundary (TMB)
  3. Stable surface-based layer over the Piedmont
  4. Deep moisture between TMB and cold front
  5. Relative vorticity and helicity maxima near the TMB
Meso- to Convective Scale, 0-12 hours
  1. Meso-lows and thermal-moisture gradients on the TMB
  2. CAPE > 1000 J/kg near the TMB
  3. Gravity wave potential
  4. Convective cells between TMB and cold front
  5. Storm-relative (0-3 km) helicity > 150 (m/s)²
    1. Cells moving 40 knots or faster
    2. Cells right-moving relative to the 0-6 km mean wind
  6. Drying aloft behind convective clusters