Up to seven inches of rain possible this weekend

Several rounds of showers and thunderstorms are expected from Saturday through Monday with widespread rainfall totals of 3 to 7 inches likely with locally higher amounts possible.

The National Weather Service forecast discussion reports: “By Saturday night, the consensus among High Resolution Ensemble Forecast (HREF) members is a corridor of training showers and thunderstorms somewhere in close proximity of the I-44 corridor.

This is due to a strengthening low-level jet with increasing isentropic ascent, which may result in continuous redevelopment on the southwest flank of the complex. The flash flooding threat will increase markedly where this zone of training convection occurs. Given this signal, a Flood Watch was issued along and near the I-44 corridor. The 50th percentile of the HREF indicates 2 to 5 inches of rainfall in this corridor through early Sunday morning. The 90th percentile (e.g., reasonable worse case scenario or “how bad could it be?”) indicates 3 to 7 inches.

“In addition, with a strengthening low-level jet and attendant increase of low-level wind shear, the threat for damaging wind gusts will increase. If thunderstorms develop into a linear structure and are able to maintain a balanced or slightly shear dominant updraft convergence zone (UDCZ), QLCS mesovortices may develop with the potential for enhanced, damaging winds and tornadoes. However, one mitigating factor for any tornado potential appears to be limited instability at this time.

“There might be a relative lull Sunday morning (though convection will likely not completely cease) before another round develops later on Sunday. There is potential of multiple rounds through Sunday night, which will further increase the flooding risk.

“Increasing moisture and vertical wind shear will also result in an increasing potential for severe weather Sunday into Sunday night. The magnitude of the severe weather risk still remains highly dependent on the amount of instability.”