No rain in sight for San Francisco Bay Space
No rain in sight for the next 10 days in the San Francisco Bay Area, a worrying dry spell for a drought-stricken region.
Although there is evidence of a shift towards wetter and cooler conditions towards mid-December, some experts say the rain forecast doesn’t look convincing.
“We look after 10-14 days, and even after that, it doesn’t look like there’s any significant rain falling on the horizon,” said Brian Garcia, a meteorologist with the National Weather Service. “It’s just me. I really don’t think we’ll get any significant rain for the rest of the calendar year.”
Local forecaster Jan Null from Golden Gate Weather Services is more hopeful. Zero said we have more than a full month to go to rain before the end of the year.
“I wouldn’t go that far,” he said of the possibility that it wouldn’t rain in December. “I would be surprised if we didn’t see rain.”
Null found that 1997 models when he was working for the weather service showed a high pressure over the region with no rain in the long-term forecast. Then, two days before the New Year, the models suggested storm activity. “It was an atmospheric river, the way to Hawaii,” said Null. “In two days the models have changed a lot. The models are obviously better now.”
Strong, cross-model ensemble agreement that the very dry and unusually warm pattern in the western US will continue for the next 10+ days. Indications of cold / wet shift towards mid-December, but nothing convincing yet. In some places (especially in CO) the last snowfalls are recorded. #CAwx #COwx pic.twitter.com/dIxwToUbWa
– Daniel Swain (@Weather_West) November 27, 2021
The weather service is looking at a dozen forecast models that will help to determine the weather exactly within two weeks. It is difficult to predict the weather with accuracy greater than seven days, but these models can suggest conditions beyond a week. Garcia said the models were in a pattern where each rain signal was postponed until the end of the forecast period. They let them run one day and they give a weak signal for 14 days of rain. The next day the probability of rain is still 14 days off.
“When that happens, the models try to turn to a climatological solution because we’re supposed to see rain at this time of year. But it doesn’t happen, so it keeps pushing him back,” Garcia explained. “When we see this continual setback, we know there will be no rain.”
Look out for plenty of sunshine and cool mornings and warm afternoons over the next few days. It still seems we will stay rain free until the end of the month. #cawx pic.twitter.com/67cOaNzChV
– NWS Bay Area (@NWSBayArea) November 28, 2021
The San Francisco Bay Area got off to a promising start to the rainy season.
A historic atmospheric river soaked Northern California in October, and rainfall totals shot out above normal. It was a monstrous storm rarely seen this early in the rainy season, and the humid season in Northern California put an end to the wildfires. Another storm swept the region in November, weaker than in October but still rich in moisture. It has rained little in the Bay Area since then.
In October the total rainfall was hundreds of percentage points above normal. Downtown San Francisco recorded 7.04 inches of rain in October – that’s 750% above the average. Santa Rosa Airport was 10.76 inches (647% of normal) and Oakland Airport was 5.32 inches (605% of normal).
November will likely be drier than normal in the Bay Area. San Francisco has recorded 1.28 inches of rain since November 1; The normal rainfall for the month is 2.6 inches.
“It’s the time to give, but the atmosphere won’t bring us rain,” said Garcia. “It will give us sunshine.”
This is bad news for the Bay Area, where the drought persists after two consecutive dry winters.
The San Francisco Public Utilities Commission declared a water shortage on Tuesday and urged nearly 3 million of its customers in San Francisco and three other Bay Area counties to take shorter showers and conserve water.
The commission supplies water to residents of San Francisco and wholesale water to customers in parts of Alameda, San Mateo, and Santa Clara counties. The statement calls for a 5% reduction in water use in San Francisco and a 13.7% reduction in wholesale customers. The cuts are based on fiscal year 2019-2020 levels, the commission said.
