SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1236 AM CDT Tue Jun 03 2025 Valid 031200Z - 041200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS GREAT PLAINS TO THE MIDWEST... ...SUMMARY... Scattered severe thunderstorms are possible from the southern Great Plains to the Midwest. Damaging winds and large hail are the primary concern. ...Great Plains to the Midwest... Large-scale pattern is not forecast to change appreciably during the day1 period with upper troughing forecast to persist across the northern Plains as a secondary upper low digs into the southwestern U.S. by 04/12z. Even so, the progression of a notable short-wave trough into the central Plains by afternoon will encourage a seasonally strong cold front to surge south across the Great Plains. By early evening, the frontal position should extend across central WI-central MO-central OK-TX South Plains. This boundary will serve as the primary focus for robust convection through the period, especially during the afternoon/evening. Early this morning, a considerable amount of convection has evolved across the central Plains along the aforementioned cold front. Latest radar data supports 00z model guidance, and substantial thunderstorm clusters should be ongoing at the start of the period from eastern KS into IA, as the LLJ will be focused into this region of the Plains. While some of this activity may be locally severe, the primary concern for severe is later in the afternoon as the boundary layer warms/destabilizes. Strongest boundary-layer heating is forecast across the southern High Plains from eastern NM into western OK; although, a narrow zone of modest heating is expected ahead of the front into central IL. This corridor is where the strongest destabilization will occur, with upwards of 3000 J/kg SBCAPE possible. Forecast soundings suggest convective temperatures will be breached fairly early, as 700mb temperatures are not that warm along the front. While mid-level temperatures/lapse rates are not particularly noteworthy, high PW air mass and a convergent surface front, coupled with large-scale support aloft, favor a convectively-active day. By late afternoon, widespread convection may be noted along/ahead of the front, and this zone should gradually sag south and east into the overnight hours. Wind and hail are the primary concerns with clusters and line segments that develop. While some supercell risk will be noted, especially early in the convective cycle, storm mergers and clustering should dominate. ..Darrow/Wendt.. 06/03/2025