Bay Area gets rain, thunder — even hail?
Second of two storms this week should drench Bay Area into today
Bay Area residents woke up Thursday to the biggest storm to hit the region in recent memory, with thunderstorms and hail possible as the storm moved through the region.
The second of two storms this week shifted inland Wednesday, bringing widespread rain Thursday morning, with a second boundary over the North Bay and winds moving behind the front, according to the National Weather Service.
Showers were expected to persist into Thursday night in some areas, along with a shot of colder air that could result in “pea to small marble-size” hail, before petering out by midday today. Another quarter to half an inch of rainfall at lower elevations is possible over the next 24 hours, and the North Bay could get up to quarter of an inch. The wettest spots will be the coastal slopes of Santa Cruz and San Mateo counties and in the East Bay.
“They're going to be hitor-miss whack-a-mole,” said NWS forecaster Drew Peterson. “The thunderstorms could pop in one place and not another.”
As of 4 p.m. Thursday, 24hour rain totals included: 0.76 inch at Middle Peak at Mount Tamalpais, 0.74 inch at Ben Lomond, 1.05 inches at Mount Diablo, .60 of an inch in Redwood City, .36 of an inch in downtown San Francisco, .40 of an inch in Oakland and .14 of an inch at the San Jose airport.
Heavy mountain snow at the Sierra Nevada was expected to make travel hazardous through today, with long delays and possible road closures. Donner Summit, Echo Summit and Luther Pass could get up to 21/2 feet of snow during the storm, and Carson Pass and other elevations above 7,000 feet could get up to 3 feet.
The weather service has highly discouraged mountain travel during the storm but encourages bringing chains if travel is necessary.
Mild temperatures
High pressure is expected to build up again over the weekend, ushering in springtime weather with Saturday daytime highs in the 70s and temperatures reaching a fewer degrees warmer Sunday. Similarly mild temperatures are expected next week.
Some projections are indicating that another weak storm could brush across Northern California, with chances for light rain, at the end of the month.
Because January, February and March were the driest three months of any year in Northern California history since 1849 — when weather records began — the storm appeared to be significant compared with the rest of the calendar year, but it's not out of the ordinary for this time of the year, according to Peterson.
“There's a bit of a dry bias so any storm that's coming through, we're seeing it through a different lens,” he said. “Just looking historically at 30-year normals, this has been a fairly normal April. We just have the perspective of it being so dry January through March that it seems so much wetter.”
The Livermore airport, which received .80 of an inch of rain as of Wednesday at midnight, was .05 away from normal for the month.
“For many locations prior to this storm for the month of April were actually below normal for the month,” Peterson added. “It's taking this storm to get us to normal but we're not even close to record rainfall.”
Atmospheric river storms back in October and December raised hopes of easing the drought, but the dry start to the calendar year dashed most of those chances. The statewide Sierra Nevada snowpack, which fulfills about 30% of the state's water needs, was at 168% of normal on New Year's Day but had dwindled to 30% Wednesday, according to the California Department of Water Resources.
The U.S. Drought Monitor reported Thursday that about 96% of California is in severe drought, an increase from 87% from the beginning of March, and about 41% of the state is in extreme drought, up from 13%.
Extreme drought has spread to the North Coast, and all nine Bay Area counties are currently in a severe drought.
“The fact that it's impacting us over a couple days, it's a slower-moving larger system for April but it's not going to wash away the drought and not going to make it a record April month,” Peterson said. “It's a late-season storm system.”