The National Weather Service has issued a weather advisory for the Bay Area, indicating the imminent arrival of a significant storm system that is expected to bring a barrage of heavy rainfall, strong winds, and potential flooding to the region. According to meteorologists, a deep upper low is set to move into the area starting late Tuesday, fueled by a robust Pacific jet that will dig a trough to the southeast, while a downstream ridge over the United States moves to the northeast.
Ensemble guidance from the National Weather Service shows consensus on a scenario where a surface trough, extending from a deep parent surface low near British Columbia, will traverse the Bay Area and Central Coast on Wednesday. The forecast indicates a high level of confidence in experiencing periods of moderate to heavy rainfall during the frontal passage on Wednesday. However, the likelihood of a stalling system remains slim at this point.
The initial frontal passage, expected to occur within a 24-hour period, is anticipated to bring the most impactful rainfall. Forecasters advise focusing on exceedance probabilities during this timeframe rather than the total rainfall throughout the week. The highest rainfall rates are predicted to begin Wednesday morning for the North Bay, spreading southward through the day.