Severe Storm Outlook Narrative (AC)
Issued by NWS
Issued by NWS
879 ACUS02 KWNS 161738 SWODY2 SPC AC 161737 Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1237 PM CDT Sun Jun 16 2024 Valid 171200Z - 181200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS OVER PARTS OF NORTHERN PLAINS AND UPPER MISSISSIPPI VALLEY... ...SUMMARY... Scattered strong to severe storms will be possible Monday over much of the northern Plains toward the upper Mississippi Valley. ...Synopsis and Discussion... Upper pattern early Monday morning is forecast to feature expansive ridging centered over the Carolinas that covers much of the eastern CONUS and a cyclone over the Pacific Northwest with associated troughing over the much of the western CONUS. Southwesterly flow aloft will persist across the northern and central Plains between these two features, with some strengthening of this flow anticipated as the western CONUS cyclone progresses eastward across the northern Rockies and northern High Plains, and the ridging over the eastern CONUS remains in place. Scattered showers and thunderstorms will likely be ongoing from the mid MO Valley into the Upper Midwest, to the north of a warm front expected to extend from a surface low over the southwest NE/northwest KS vicinity northeastward to another low near the WI/MI border. These showers and thunderstorms are expected to gradually shift northeastward throughout the day, remaining mostly north of the warm front. There is some chance that this activity restrengthens during the late afternoon/early evening over east-central MN and central/northern WI, where the warm front is expected to make gradual northward progress during the day. Ample low-level moisture and strong buoyancy south of the warm front suggests surface-based supercells capable of all severe hazards, including tornadoes, are possible. However, the overall evolution of this convective cluster still remains a bit uncertain, with some guidance keeping it well north of the warm front. This uncertainty precludes higher probabilities in this outlook. Farther west, late afternoon thunderstorm development appears possible along the lee trough arcing from southeast MT south into far eastern CO/western KS. Highest probabilities for surface-based, late afternoon/early evening storms appears to be across the central High Plains. Any storms that do form could produce hail initially, before quickly becoming more outflow dominant. There is some potential storms develop close enough to one another for upscale growth, with the resulting convective line progressing east-northeastward across southern NE. Thunderstorm development also appears probable across southeast MT amid moisture upslope flow and strengthening large-scale ascent ahead of the approaching shortwave trough. These storms will likely be elevated, with hail as the primary hazard, but a few strong gusts could still reach the surface. Isolated storms are possible farther south across the southern High Plains, but warmer temperatures aloft and displacement south of the better large-scale ascent should keep coverage isolated. High-based character to any storms that do develop could promote damaging gusts. The low-level jet is expected to strengthen during the evening, likely increasing to near 60 kt from the central Plains into the Upper Midwest. Associated warm-air advection will likely result in thunderstorm development north of the warm front across the northern Plains and Upper Midwest. Enough vertical shear and elevated buoyancy is in place for severe storms, with large hail as the primary hazards. This activity is currently expected to stay north of the warm front, but this front is forecast to move northward through much of MN by early Tuesday. As a result, these is some chance a storms may trend towards becoming surface-based early Tuesday morning if they develop far enough south. ..Mosier.. 06/16/2024 $$