NWS Radar

The instrument

Radar

KMUX — NWS San Francisco Bay Area

Site

Mt Umunhum, 3,469 ft

From here

22.4 mi, bearing 148°

Type

WSR-88D, S band, dual polarized

Product

Base reflectivity, 0.5° tilt

What you are looking at

Reflectivity is how much of the beam came back, not how much rain reached the ground. At 22 miles the 0.5° beam is a third of a mile across and its center passes about 4,700 ft above Palo Alto — well over the top of the low stratus and drizzle that does most of our winter wetting. A blank screen here is not the same as a dry morning.

Each frame carries its own observation time and the dBZ color scale, printed by NWS along the bottom edge. Those two are the authority; nothing on this page restates them.