SPC 1930Z Day 3 Outlook
Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0124 PM CST Sun Dec 21 2025 Valid 231200Z - 241200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Organized severe thunderstorms are not currently forecast across the contiguous United States on Tuesday or Tuesday night. ...California... Within large-scale upper troughing over the eastern Pacific, a mid-level shortwave trough and associated jet will overspread much of northern/central CA Tuesday through Tuesday night. An attendant surface low is forecast to develop northward along/near the coast of northern/central CA late Tuesday night into early Wednesday morning. Ample low-level and deep-layer shear will be present over this region owing to strengthening flow aloft with the approaching shortwave trough. However, considerable uncertainty still exists regarding the depth/quality of low-level moisture and whether enough instability will exist to support a meaningful change for surface-based thunderstorms given the unfavorable time of night and generally modest lapse rates. Some of the more aggressive guidance (12Z RRFS) suggests that weak but sufficient MLCAPE may develop late Tuesday into early Wednesday to support some threat for strong/gusty winds with thunderstorms as mid-level temperatures gradually cool with the shortwave trough overspreading the CA Coast. Based on a consensus of other available guidance, this potential still appears a bit too uncertain/conditional to include low severe probabilities along the CA Coast at this time. Regardless, the chance for elevated convection remains apparent, and the general thunderstorm area has been expanded across more of CA with this update. ..Gleason.. 12/21/2025
