SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0739 AM CDT Tue Mar 18 2025 Valid 181300Z - 191200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS LATE TONIGHT FROM EASTERN NE INTO IA... ...SUMMARY... Isolated, marginally severe hail is possible late tonight from eastern Nebraska across much of Iowa. ...Eastern NE/IA late tonight and early Wednesday... In advance of a pronounced midlevel shortwave trough over UT/northern AZ this morning, a surface lee cyclone will deepen across western KS and then move to far northwest MO by early Wednesday. Moisture return in the warm sector of this deepening cyclone will be limited by a prior frontal passage across the Gulf/northwest Caribbean, with only a narrow corridor of low-mid 50s boundary-layer dewpoints expected from eastern OK to far northwest MO. Though the warm sector will remain capped through the period, there could be sufficient ascent/moistening for elevated thunderstorm development by 06-12z from eastern NE across IA. Steep midlevel lapse rates and relatively cold midlevel temperatures will contribute to MUCAPE of 500-750 J/kg and the potential for isolated large hail (a few instances near 1 inch diameter) with elevated convection to the cool side of a baroclinic zone across eastern NE/IA. ..Thompson/Dean.. 03/18/2025