1AM Day 3 Convective Outlook for Tuesday, July 15. THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE NORTHERN AND CENTRAL PLAINS TO THE UPPER MIDWEST
SUMMARY
Isolated strong to severe thunderstorms are possible Tuesday afternoon and evening across portions of the central Plains to Upper Midwest.
Northern/Central Plains to the Upper Midwest
An upper trough will develop eastward across the northern Plains toward the Upper Midwest on Tuesday. At the surface, a cold front is forecast to spread southeast across the Dakotas/NE, becoming positioned from the Upper MS Valley to northern KS by Wednesday morning. Ahead of the front, a seasonally moist airmass will be in place. Steep low and midlevel lapse rates will support moderate to strong destabilization, and thunderstorms should develop by mid-to-late afternoon as large-scale ascent increases. Deep-layer flow is not forecast to be overly strong, with effective shear magnitudes in forecast soundings generally around 25-30 kt. Given favorable thermodynamic profiles, this should be more than sufficient for scattered organized cells capable of produce strong gusts and hail from NE/SD into MN, necessitating a Marginal (level 1 of 5) risk.
Mid-MS Valley
A remnant low/MCV is forecast to move across MO/IL/IA on Tuesday. A very moist airmass will be in place, with surface dewpoints into the 70s and PW values near 2 inches. This will aid in moderate destabilization, though forecast lapse rates are modest. Furthermore, deep-layer flow will be modest, though some local enhancement near the low/MCV is possible. Quite a bit of spread in noted in forecast guidance regarding the strength of this feature, and several rounds of convection are possible in the days prior to Tuesday. At this time, severe potential appears limited, but isolated strong gusts could.