Here is a quick discussion from the NWS Birmingham:
“Projections for 18Z (noon) from RUC model…MUCAPE will be above 150 J/kg over northwest counties…and southwest counties. MUCAPE above 300 J/kg is expected over Perry…Marengo…and Dallas counties. Even so, this is only marginal instability. 0-6 km shear is increasing each hour…and by 18Z will vary from 90 kts over the northwest to 60 to 70 kts south of I-20. These are very high shear values. If a deep updraft can sustain itself in this kind of shear…it will spell trouble. 0-3 km SRH values will be above 500 m2/s2 over most of the forecast area. Right now, the shear is overwhelming the instability.”
BOTTOM LINE: No real change in our thinking. Main threat will be from straight line winds with the squall line, but a few isolated tornadoes are not out of the question where instability values will be higher. Classic early season system with high shear and low instability. More updates shortly…
