1PM Day 3 Convective Outlook for Friday, March 6. THERE IS AN ENHANCED RISK OF SEVERE THUNDERSTORMS FROM EASTERN KS/OK TO WESTERN MO
SUMMARY
Scattered severe thunderstorms are expected from late afternoon Friday through Friday night from portions of the central/southern Great Plains to the Midwest. The most probable corridor for tornadoes, damaging winds, and large hail is across eastern portions of Kansas and Oklahoma to western Missouri.
Synopsis
Broad upper trough over the West should split into two distinct impulses by Friday night. Leading shortwave trough should eject from the Four Corners across the central Great Plains to the Upper Mississippi Valley, while a backside cutoff low evolves over the Lower CO Valley. Lead cyclone should track from western KS vicinity across IA to the central Great Lakes. The dryline should mix towards central OK/TX through late afternoon. A surface cold front will accelerate southeastward across the central/southern Great Plains on the backside of the lead cyclone.
Central/southern Great Plains into the Midwest
Most appreciable change this outlook has been to flatten the previously tight gradient to severe probabilities over the Great Plains. The splitting of the broad western trough and positive-tilt of the leading shortwave impulse suggests that surface features on Friday afternoon should lag westward compared to the typically overmixed GFS. Initial storm development should occur across central KS near the triple-point mesolow by mid to late afternoon. Expanding convective coverage is anticipated to the northeast into IA/MO and south into at least northern OK. Available D3 CAM guidance is much less robust than parameterized models with the degree of convective development through early evening towards the Red River and southward into central TX. With near-neutral mid-level height falls, it is plausible that convection south of the latitudinally compact mid-level jetlet will remain isolated. This lowers confidence in the southern extent of highlighted level 3-ENH risk across most of OK.
Across eastern KS, northern OK, and western Missouri, initial supercells will probably grow upscale into a broader QLCS during the evening, with semi-discrete activity favored along the southern flank. Strengthening 850-700 mb southwesterlies suggest damaging wind and QLCS tornado potential could persist across the Mid-MS Valley towards the Lake MI vicinity overnight in a weak MLCAPE/high shear environment. Available CAM guidance does indicate a general alignment of QLCS with the deep-layer shear vector, suggesting of a sporadic severe threat mainly where embedded bowing segments/surges can develop.
Farther south, storm development will become increasingly probable as the accelerating cold front overtakes and merges with the front on Friday night. Outside of frontal convergence and low-level warm advection atop the undercutting front in western TX, large-scale ascent should remain nebulous. Large hail may accompany initial updrafts, with severe wind/tornado potential nocturnally limited.