Inversion near ~797ft MSL — a lower deck is likely along the coast and bay edge.
Weak inversion (4.3°F) — marine layer may be mixing out.
Coastal T-Td spread ≤2.3°F — marine air mass present at surface.
SST 53.4°F at Buoy 46026.
Cloud bases relatively steady.
No temperature inversion detected in sounding.
What it measures: Each hourly point is the average sea-level pressure from KSFO, KHAF, KNUQ, KOAR, minus the average from KCCR, KLVK, KAPC, KSTS, KSJC, KSNS. Only stations with a valid pressure report in that hour are included.
What it means: A larger positive value usually means a stronger coast-to-valley onshore push, which favors marine air pressing farther inland. Values near zero mean the push is weak. A negative value means valley pressure is higher than the coast, which usually means little help for marine air moving inland. This is a pressure-push signal, not a direct measurement of marine-layer depth.