The Bay Area faces ongoing elevated fire weather conditions today due to a combination of factors, including gusty winds and low relative humidity, particularly affecting cured grass areas. The National Weather Service in San Francisco warns of an increased threat for grass fires, advising the public to stay vigilant and avoid activities that could lead to fire ignition. "The combination of poor daytime relative humidity of 15-25% and onshore winds with gusts of 25-35 mph along the immediate coastline, in northwest/southeast oriented valleys, and in the higher terrain will continue to support elevated fire weather conditions today," reads a statement from the NWS San Francisco.
As per the latest Area Forecast Discussion by the NWS, strong onshore winds are expected to bring 25-35 mph gusts over waters and along coastlines. This wind event, paired with the low relative humidity values only slightly above the lower percentile, adds to the critical fire weather scenario. Forecasts also show that current temperatures will drop back to seasonal normals due to an upper-level shortwave trough skirting the region.
Looking ahead, there appears to be some reprieve from the risky conditions. The impending arrival of a deeper upper-level shortwave trough will deepen the marine layer, enabling better relative humidity recovery and consequently easing fire concerns for a moment in time. The NWS notes that humidity recovery will surpass 70% in all but the highest terrain of the Central Coast, bringing temperatures down to 5 degrees below normal on Friday. In addition, a build-up of upper-level longwave ridge into the West is expected to stabilize temperatures by Saturday, according to the forecast.
Mariners are also advised to exercise caution as widespread hazardous marine conditions are expected to continue. The latest marine bulletin by the National Weather Service states, "Widespread hazardous marine conditions continue today as strong northwesterly breezes with near gale to gale force gusts and rough seas persist." Small Craft Advisories and even a Gale Warning have been issued for certain zones off the coast, highlighting the urgency for those at sea to take heed of these rough conditions.
