SPC 2000Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0158 PM CST Mon Dec 14 2020 Valid 142000Z - 151200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... The strong/gusty wind threat associated with thunderstorms has decreased across eastern North Carolina. Minimal thunderstorm potential is evident across the rest of the contiguous United States through tonight. ...20Z Update... A surface cold front is in the process of clearing the NC Coast, and any isolated strong/gusty wind threat associated with convection is quickly moving offshore. Therefore, low severe wind probabilities have been removed from eastern NC with this update. Thunderstorms are not expected across the remainder of the CONUS through the end of the period owing to dry and/or stable conditions. ..Gleason.. 12/14/2020 .PREV DISCUSSION... /ISSUED 1008 AM CST Mon Dec 14 2020/ ...Eastern NC... Late this morning a cold front extends from a weak surface low over the northern Coastal Plain of NC, through central GA, the central FL Panhandle and into the eastern Gulf. Quasi-stationary front extends from the surface low through northeastern NC and into southeast VA. The low will track northeast and offshore by early afternoon, while the cold front continues east and off the Atlantic Coast by mid afternoon. Warm sector dewpoints across eastern NC have risen to the low to mid 60s F, but instability remains limited due to widespread clouds and showers with MUCAPE from 200-400 J/kg for parcels lifted from near 850 mb. The ongoing area of showers with a few embedded thunderstorms developing along the warm conveyor belt will continue east during the day. Some potential will exist for this shallow convection to become surface based as it encounters a warmer and more unstable boundary layer across eastern NC, though instability will remain very marginal. Given very strong vertical wind profiles with 60 kt as low as 0.5 km AGL, some of this higher momentum air could be transported to the surface within the higher reflectively rain bands as the surface layer destabilizes farther east. However, tendency is for the accompanying shortwave trough to deamplify with only weak cyclogenesis inland which, combined with the very marginal thermodynamic environment, should limit overall severe threat.
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