SPC 0830Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0207 AM CST Wed Nov 18 2020 Valid 201200Z - 211200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Organized severe thunderstorms are not expected on Friday or Friday night. ...Synopsis... Quasi-zonal upper-level pattern will persist across much of the CONUS east of the Rockies on Day 3/Friday. At the surface, strong high pressure will generally lead to dry and stable conditions. Across the western states, a mid/upper shortwave trough over the Pacific Northwest early in the period will develop southeast across the Great Basin and northern Rockies. This will result in height falls across the southern Rockies and adjacent Plains late in the period, inducing a lee low over the central/southern High Plains. In response, modest Gulf moisture will stream northward through the southern Plains ahead of stalled front across the central Plains to the Mid-MS Valley vicinity. This warm advection regime will likely result in developing showers from the Four Corners into the central/southern Plains and parts of the Midwest along the aforementioned boundary. However, thunderstorm activity should be sparse due to weak instability and poor lapse rates. The exception may be across parts of the higher terrain of SW CO/NW NM where cooling aloft will result in steepening midlevel lapse rates, and deep layer flow will increase with the approach of the trough. A few lightning flashes may occur in this area from late Friday evening into the overnight hours. ..Leitman.. 11/18/2020
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