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000 ACUS01 KWNS 201119 SWODY1 SPC AC 201117 Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0517 AM CST Mon Jan 20 2020 Valid 201300Z - 211200Z ...NO THUNDERSTORM AREAS FORECAST... ...SUMMARY... Thunderstorm areas are not expected over the contiguous U.S. today and tonight. ...Synopsis... A rather highly amplified, yet still progressive, upper-air pattern will prevail over the CONUS this period. A strong shortwave trough -- now located over eastern SD, southern MN and WI -- will dig southeastward across the mid Mississippi and Tennessee Valley through the period, while gradually intensifying. By 12Z, a closed, elongated, positively tilted 500-mb cyclone should develop along this trough over northern GA and vicinity. Upstream, a high- amplitude ridge will shift eastward from the Rockies across the Great Plains. Associated low-level frontal passages have rendered the inland boundary layer too cold, dry and/or stable to support deep convection over land. Behind that, heights will fall across much of the West as a series of perturbations approaches and/or moves inland from the Pacific. The strongest such feature is a cyclone whose center is apparent in moisture-channel imagery near 44N141W. As this vortex approaches the Pacific Northwest, it will assume a more-negative tilt, with a basal shortwave trough/vorticity banner approaching the OR coastline at 12Z. This feature will be preceded by a lengthy fetch of low-level warm advection and a baroclinic cloud/precip band, but with time series of forecast soundings reasonably showing lapse rates in ideal icing layers too stable to support thunder potential. While a lightning strike cannot be ruled out in the last few hours of the period, in the eastern edge of the colder air aloft preceding the cyclone, potential appears too isolated to justify an outlook area. ..Edwards.. 01/20/2020 $$