From a weather watcher’s perspective, the most striking thing about Thursday, aka Round 1 in our latest series of storms, was the variation in rainfall from north to south.
As widely noted, an atmospheric river of very moist air streaming in to the coast from near Hawaii remained stubbornly focused on the counties north of the Golden Gate for most of the day. That meant the wettest locations — and the Middle Peak weather station on Mount Tamalpais recorded the most rain for the 24 hours ended at midnight Thursday — topped 4 inches.
Meantime, the South Bay got close to nothing from the storm. Lowland locations and upland locations alike got a mere moistening: Mountain View recorded .02 of an inch. Mount Umunhum, which got 11 inches of rain from the storms late last week, got just .04 inches.
Yes, that’s a bit of an apples-and-oranges comparison, measuring Thursday’s one-day rain totals against a four-day series of storms last week. But the Thursday storm did show off how tightly focused an atmospheric-river-type storm can be.