Strong winds, gravity waves and turbulence across Northern California
6.9 µm) images which included Pilot Reports (PIREPS) of turbulence (above) revealed a diverse variety of gravity waves across much of Northern California on 19 January 2021. Three types of waves were prevalent: (1) quasi-stationary mountain waves caused by strong northeasterly flow interacting with topography of the Sierra Nevada and Coastal Ranges, (2) long, narrow corridors of fast-moving waves flowing offshore, and (3) west-to-east oriented arcs of waves drifting slowly northward (against the ambient flow). With such disparate wave structures and the intersections of their wave fronts, the prospects for atmospheric turbulence were elevated — in fact, there were a few pilot reports of moderate to severe turbulence, at both low and high altitudes.GOES-17 (GOES-West) Mid-level Water Vapor (
GOES-17 Mid-level Water Vapor images with plots of NAM40 model 500 hPa wind streamlines/isotachs at 18 UTC and 00 UTC (below) showed the strong northeasterly flow in the middle troposphere, with speeds as high as 100-110 knots.