SPC 0730Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0224 AM CDT Sat Oct 17 2020 Valid 191200Z - 201200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS PARTS OF THE MID MISSISSIPPI VALLEY... ...SUMMARY... Thunderstorms associated with hail and strong gusty winds will be possible on Monday across parts of the mid Mississippi Valley. ...Mid Mississippi Valley... An upper-level trough is forecast to move eastward into the mid to upper Mississippi Valley on Monday. At the surface, a cold front is forecast to move southeastward across Arklatex, mid Mississippi Valley and Ohio Valley. Ahead of the front, surface dewpoints should increase into the lower to mid 60s F across the mid Mississippi Valley allowing for a narrow corridor of instability to develop during the afternoon. As low-level convergence increases along and just south of the front Monday afternoon, the formation of a line of thunderstorms will be possible from Arkansas northeastward into western Kentucky. NAM forecast soundings along this corridor for 00Z/Tuesday from near Little Rock have MUCAPE near 2000 J/kg with 0-6 km shear around 30 kt. Although MUCAPE decreases some with northeastward extent, 0-6 km shear is forecast to be near 45 kt in western Kentucky. The combination of instability and shear along this corridor should be adequate for an isolated severe threat. Wind damage and hail would be the primary hazards. Due to uncertainty concerning the exact front position and magnitude of instability will go with a marginal risk. The risk may need to be upgraded in later outlooks for Monday but that will depend upon where parameters become maximized in later model runs. ..Broyles.. 10/17/2020
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