SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0221 PM CDT Wed Oct 14 2020 Valid 142000Z - 151200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FROM PARTS OF EAST-CENTRAL MINNESOTA INTO NORTHWEST WISCONSIN... ...SUMMARY... A strong/severe wind gust or two may occur this afternoon over portions of the upper Mississippi Valley region. No changes made to the previous outlook. A low-end/conditional threat of a strong or severe gust remains possible with any shallow convection that develops in association with the strong upper vorticity maximum over the upper Mississippi Valley. Otherwise, isolated lighting strikes are possible extending westward across the northern High Plains, where gusty winds are ongoing. ..Jewell.. 10/14/2020 .PREV DISCUSSION... /ISSUED 1100 AM CDT Wed Oct 14 2020/ ...Upper MS Valley this afternoon/evening... A midlevel shortwave trough and associated surface cyclone over the Dakotas will progress east-southeastward over the upper MS Valley this afternoon/evening. This will occur within an amplifying larger-scale trough over the north central CONUS (downstream from a building ridge over the eastern Pacific). Cold midlevel temperatures and steep lapse rates, in combination with daytime heating in cloud breaks and residual boundary-layer dewpoints in the 40s, will support surface-based CAPE around 250 J/kg this afternoon in the warm sector just south-southeast of the surface cyclone. Surface heating/mixing and ascent within the left-exit region of the mid-upper jet should support at least isolated thunderstorms this afternoon. The combination of steep low-level lapse rates, 50 kt midlevel flow and long hodographs will support some threat for fast-moving cells capable of producing isolated strong/damaging gusts. Gusty winds may also occur with low-topped, skeletal convection along the trailing cold front into the northern High Plains. ...Elsewhere... A warm advection regime will persist into tonight across the Ozarks in advance of a cold front moving southeastward across the central Plains. There may be sufficient moistening for some elevated showers late tonight in the vicinity of southwest MO, but elevated thunderstorms appear unlikely. Shallow convection is expected along residual boundaries near the northeast FL/GA coasts and the middle TX coast, but the threat for deep convection with lightning appears minimal.
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