SPC 1200Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0100 AM CDT Fri Jul 30 2021 Valid 301200Z - 311200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM A PORTION OF THE CENTRAL PLAINS INTO THE MIDDLE MISSISSIPPI VALLEY REGION... ...SUMMARY... Thunderstorms with severe gusts are possible Friday afternoon into the evening across parts of Nebraska, Iowa and northern Missouri. A few storms might also produce strong gusts over a portion of the Carolinas. ...Central Plains into the Middle Mississippi Valley region... Stationary front now situated near the NE/KS border may move north as a warm front today and become situated from central NE southeast through central MO Friday afternoon and evening. Rich low-level moisture with near 70F dewpoints will persist in the vicinity of this boundary, and diabatic heating of the surface layer is expected in the warm sector to the south. Cluster of storms currently over northeast WY will persist into the early morning and likely be situated across southern SD by 12Z. These storms are associated with a vorticity maximum moving through the northern periphery of an upper ridge, and this activity will spread southeast through IA during the day. Modest inflow from the destabilizing warm sector might result in some intensification of ongoing storms. Additional storms may also develop within the corridor of isentropic ascent along and north of the warm front. While most of these storms might initially be slightly elevated, they may eventually become rooted near the surface. Effective bulk shear from 35-40 kt will support potential for organization with any surface-based updrafts. Some CAMs indicate activity might evolve into a forward-propagating MCS that will continue southeast along the instability gradient supported by a strengthening nocturnal southwesterly low level jet. Damaging wind will be the primary threat. ...Carolinas... A cold front will move southeast into the central and eastern Carolinas later this afternoon. The pre-frontal warm sector is expected to become moderately unstable with 2000-3000 J/kg MLCAPE supported by diabatic heating of the moist surface layer. Warm mid-level temperatures will result in weak lapse rates in the 850-500 mb layer. WV imagery also shows a reservoir of relatively dry air between 700-500 mb that will spread southeast into this region. While thunderstorms will likely initiate along the front during afternoon peak heating, the expected relatively warm air aloft and poor lapse rates, along with weak to modest vertical shear will limit overall updraft strength. Nevertheless, some storms may become capable of producing isolated downbursts as they spread southeast during the afternoon into the early evening, before weakening as the boundary layer stabilizes. ..Dial/Moore.. 07/30/2021 Read more LIVE: spc.noaa.gov
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