SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 1230 AM CDT Fri Sep 03 2021 Valid 031200Z - 041200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE NORTHERN AND CENTRAL PLAINS... ...SUMMARY... Isolated severe storms will be possible this afternoon through tonight across portions of the northern and central Plains. Damaging wind gusts and isolated hail will be the primary threats. ...Synopsis... A mid/upper-level trough is forecast to move across the central and northern Plains today, resulting in dampening of the upper ridge over the southern Plains. A cold front is forecast to move slowly southward into southeast CO/southern KS/central MO by late tonight, with weak surface cyclogenesis possible across the southern High Plains. ...Eastern WY...Southwest SD...Western NE...Northeast CO... A weak upslope-flow regime combined with the approaching upper trough should support scattered thunderstorm development across the higher terrain of eastern WY into northeast CO this afternoon. MLCAPE of 500-1000 J/kg combined with effective shear of 30-40 kt will favor some storm organization, including the potential for a supercell or two. Isolated large hail will likely be the initial threat, but a few stronger clusters may evolve with time and pose a threat of localized severe gusts (in addition to hail) as storms move eastward into portions of the High Plains during the evening. ...Southeast CO into southwest KS... A post-frontal upslope-flow regime will also be in place from southeast CO into southwest KS during the afternoon, though with richer low-level moisture compared to areas further north. Diurnal heating of the moist low-level environment will result in moderate to locally strong buoyancy, with MLCAPE potentially rising into the 1500-3000 J/kg range. Widely scattered thunderstorm development is possible this afternoon near the front across southwest KS, with more isolated development into southeast CO. Effective shear of 30-40 kt will support a few organized cells and/or clusters this afternoon/evening, with locally severe wind gusts and isolated hail expected to be the primary threats. ...Central/eastern KS...Western/central MO...Far northern OK... Despite warm temperatures aloft and weak midlevel lapse rates, diurnal heating will support MLCAPE increasing above 2000 J/kg this afternoon, near and just north of the southward-advancing cold front from central KS into MO. Isolated strong storms may develop this afternoon near the boundary, with an increase in storm coverage expected tonight in response to a strengthening low-level jet. Deep-layer shear is expected to be weaker than areas to the west and north, but should still be marginally favorable for some storm organization. A threat for isolated damaging wind may accompany the stronger cells/clusters this afternoon into tonight. ..Dean/Squitieri.. 09/03/2021 Read more LIVE: spc.noaa.gov
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