SPC 1730Z Day 2 Outlook
Day 2 Convective Outlook NWS Storm Prediction Center Norman OK 1225 PM CDT Wed Jul 11 2018 Valid 121200Z - 131200Z ...THERE IS A SLIGHT RISK OF SEVERE THUNDERSTORMS FROM NORTHERN NE TO WESTERN WI... ...SUMMARY... Severe thunderstorms are possible from northern Nebraska into western Wisconsin. ...NE to WI... Mid-level heights will be weakly suppressed across the eastern Dakotas and MN during the day2 period as primary 500mb speed max ejects across northern MN into ON. This feature will contribute to a front settling to a position from central MN...southwest into the NE Panhandle by 13/00z. With a dominant upper high expected to remain anchored over the Midwest the large-scale pattern will continue to prove favorable for higher PW air mass to extend across the High Plains, arcing into the upper Great Lakes region. Within this plume of higher moisture it appears strong boundary layer heating will contribute to the removal of inhibition for thunderstorm development. Strongest heating is expected across NE where surface temperatures climbing into the mid 90s should allow parcels to reach their convective temperatures. Forecast soundings suggest thunderstorm initiation could occur as early as 21z, especially near the front where low-level convergence will be maximized. In the absence of a large-scale feature for broader ascent, strong surface heating and frontal forcing will be the primary mechanisms for an elongated corridor of deep convection. SLGT Risk has been oriented along this wind shift where the greatest concentration of storms are expected. While damaging winds may be the greatest risk, some hail could be noted with supercell structures despite the relatively warm mid-level temperatures. ...Carolinas... Northwesterly mid-level flow will persist across the eastern US during the day2 period as anticyclone remains centered over the Midwest. This flow regime should encourage a weak surface front to sag south across the Carolinas during the day. High PW air mass, on the order of 1.75-2", will extend across this pre-frontal region where scattered thunderstorms should readily develop during the heat of the day. There is some concern that a few wet micro bursts could evolve with this activity. Given the lack of large-scale ascent, in the wake of mid-level short-wave trough, will not introduce 5% severe probs for locally damaging winds; however, thermodynamic profiles could support this type of event. Severe probs may be introduced to this region during the day1 period if/when confidence in this scenario is higher. ...MAXIMUM RISK BY HAZARD... Tornado: 2% - Marginal Wind: 15% - Slight Hail: 5% - Marginal ..Darrow.. 07/11/2018
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