11AM Day 2 Convective Outlook for Monday, February 16. THERE IS A MARGINAL RISK OF SEVERE THUNDERSTORMS FOR THE SOUTHERN CALIFORNIA COAST AND PORTIONS OF THE CENTRAL VALLEY .
SUMMARY
Strong thunderstorms may impact southern California coastal areas and perhaps parts of the Central Valley on Monday. These storms will be accompanied by at least some risk for damaging wind gusts and perhaps a tornado or two.
Synopsis
A strong mid-level trough and associated mid-level jet streak will impact southern California on Monday with an amplifying ridge across the central CONUS. The southern stream trough across southern California will merge with a northern stream trough across the Northwest during the day Monday. Therefore, a surface low which will move onshore along the southern/central California coast on Monday morning/early afternoon will combine with the northern surface low and result in a very strong surface low centered over the northern Rockies by the end of the period.
Southern California
Low-level moisture advection will lead to weak destabilization off the southern California coast Monday morning and into the early afternoon. Most CAM guidance indicates strengthening convection along the front as it approaches the coast. A strong low-level jet and some low-level hodograph curvature may support some damaging winds and potential for a QLCS tornado or two. The primary limiting factor will be the relatively shallow nature of the instability. Some areas within the line may not even produce lightning, but given the convective nature of the line and the strong wind profile, a marginal risk is warranted.
Central California
In the wake of the initial precipitation surge, cooling temperatures aloft and perhaps some heating in the Central Valley may result in a brief window during the afternoon which may favor a few stronger storms. This threat would be confined to a narrow area, but HRRR forecast soundings between 21-22Z show some weak instability, moderately steep lapse rates, and around 200 m2/s2 0-1km SRH. The 2% tornado probabilities have been maintained for this limited duration threat.