See AWWA D100-5 Welded Steel Tank For Water Storage. J is a simple idea but the emperical formula requires the the AWWA code. It is probably related to the API 650 Stability Ratio.
J = Ms/(D2{wt*(1-0.4*Av)+wl}.
Ms is the overturning moment.
See page 147 & 148 AWWA D100-S