January’s voluminous rains exorcised the specter of drought from Northern California, but the storm season is not done yet.
Thursday morning, the National Weather Service issued a Hazardous Weather Outlook for the Bay Area, warning of potentially dangerous winds set to buffet the “hills and coastal locations” with gusts ranging from 35 to 50 miles per hour.
For now, the wind warning applies only to Thursday, although rain will continue through the weekend.
In fact, some weather services predict rain for the next eight days straight across the region. Although, as always, such forecasts as tricky as, well, predicting the weather.
Winds of at least 39 MPH are equivalent to those in a tropical storm. (For comparisons, hurricane-force winds start at about 74 miles per hour.)
According to the Beaufort Wind Scale developed in 1805, at 35 miles per hour (or “near gale” winds), the “Sea heaps up [...] waves 13-19 ft, white foam streaks off breakers” and “whole trees move.”
At 40 miles per hour (“gale winds”), “Moderately high (18-25 ft) waves of greater length” manifest, and land movement is “generally impeded.”
At 50 miles per hour (“strong gale”), “High waves (23-32 ft) begin to roll” and “Slight structural damage occurs,” such as missing roof tiles.
To qualify as “strong storm winds” they have to get up 55 MPH, when 41-foot waves with “overhanging crests” appear. Such storms are “rarely experienced on land,” although the results are broken trees and pronounced structural damage.
That of course sounds markedly similar to the storms that battered San Francisco in January, but doesn’t seem to be in the cards this weekend.
- Wind Warning [National Weather Service]
- SF Forecast [Weather.com]
- Beaufort Scale [NOAA]