SPC 1300Z Day 1 Outlook
Day 1 Convective Outlook NWS Storm Prediction Center Norman OK 0655 AM CST Wed Dec 24 2025 Valid 241300Z - 251200Z ...THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS COASTAL CALIFORNIA AND THE CENTRAL VALLEY... ...SUMMARY... An isolated risk for localized severe gusts and perhaps a brief tornado will exist today into tonight along much of the California coast and the central valley. ...California... Water-vapor early this morning shows an upper trough over the eastern Pacific with a lead disturbance moving north near the northern coast of CA/southwest OR. Farther south, a mid-level vorticity maximum west of southern CA will move to the Sierra Nevada by early evening. Upstream of this disturbance and farther west, models show a more potent mid-level shortwave trough moving northeast towards the northern CA coast by 25/12z. In the low levels, a notable deepening of a cyclone is forecast tonight over the eastern Pacific to the west of the northern coast of CA. Zone of persistent and strong low-level WAA regime will aid in maintaining a persistent rain shield with shallow convection from Point Conception southward along the coast into the LA Basin this morning. Scant buoyancy will limit updraft vigor/depth, but intense flow (reference KVBX, KVTX WSR-88D VAD data) in the lowest 2-km MSL may enable an isolated risk for wind damage/severe gusts near the coast and in terrain-favored locales. A brief tornado cannot be ruled out, but this threat would likely depend on the development of stronger embedded convective elements within the larger rain shield. Later this afternoon, some convection-allowing models show low-topped convection developing within the central valley in an environment characterized by cold mid-level temperatures and a modestly moist airmass. A mini supercell risk is possible with an attendant isolated threat for a brief tornado and wind. By early evening, another round of low-topped convection is progged to develop west of the coast. This activity will focus from near Point Conception northward along the coast tonight as strengthening ascent accompanies the approach of the next mid-level wave. Elongated hodographs and weak buoyancy will support potential storm organization with the stronger storms and an isolated threat for severe wind gusts/brief tornado. ..Smith/Weinman.. 12/24/2025
