10AM Day 1 Convective Outlook for Monday, February 16. THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS ACROSS COASTAL PORTIONS OF CENTRAL AND SOUTHERN CALIFORNIA
SUMMARY
Strong thunderstorms may impact the coastal areas of central and southern California today. These storms may produce locally damaging wind gusts, and perhaps a brief tornado.
Coastal Central and Southern CA
Recent satellite imagery continues to show a strong shortwave trough off the southern CA coast. Robust low-level wind fields precede this shortwave, with recent mesoanalysis and KVBX VAD profiles showing southerly winds around 40 to 50 kt at 1 km over Santa Barbara and San Luis Obispo counties. Despite very meager buoyancy, regional radar imagery does show some deeper convective elements moving eastward/northeastward from along the Santa Barbara county coast to just west of the northern Channel Islands. Strong forcing for ascent will continue across the region throughout the day, although a southward shift is anticipated over the next few hours as a strong mid-level jet streak approaches the coast of far southern CA. This stronger forcing may result in a southward extension of the ongoing band, or the development of a separate band farther south.
Given the intense wind fields in place over the region, any deeper more sustained convection could result in localized strong gusts and perhaps even a brief tornado. Current trends suggest this severe potential will gradually shift southward across southern CA throughout the day. However, this threat should be limited/very isolated given the scant buoyancy in place and resulting expectation that any deeper convection should be brief and too shallow to produce lightning.
Coastal southwest OR and northern CA
An upper trough will dive southward just off the Pacific Northwest tonight, with the left-exit region of the upper jet pushing into northern CA early Tuesday morning. While surface temperatures will be cool (in the 40s F) in the wake of the earlier wave, this secondary trough will bring cold temperatures aloft with and 500 mb temperatures to around -35 C. As such, 100-200 J/kg of SBCAPE will exist along the immediate coast, and a few instances of low-topped convection may yield locally strong wind gusts as the cold front moves through.