Marine Air Penetration in Central California

Three-dimensional analysis shows the sea-breeze front to be primarily a wind shift line in which the thermal discontinuity lags behind the shear line and becomes quasi-stationary in the afternoon. Two synoptic patterns control the temperature regime. On cool days, when a high level trough is present the sea-breeze front is weak, moves rapidly and penetrates far inland; the marine layer is deep and the sea breeze spills over the low mountain ridges. Warm days occur, when the Pacific high penetrates into Oregon and Washington; the marine layer is shallow and the sea-breeze front is intense and slow moving.