Winds will be light to moderate through the morning, but become moderate to breezy for Monday afternoon as widespread VFR returns.
Stratus will also filter into the SF Bay leading to IFR at OAK. Stratus is building along the coast and into the Monterey Bay, causing LIFR CIGs at MRY and SNS. Mid to high clouds continue to pass through the region.
But its another solemn reminder that it is only mid September, and climatologically September and October are the primary months when dry, offshore winds develop around the Bay Area.ĪVIATION. It only just started showing up in model so for now it will be monitored. If this scenario plays out, that leads to the probability that winds can turn offshore and heighten fire concerns. Meanwhile, the Euro does not have a closed low, it keeps it a trough and brings it a bit more inland and Sunday through Tuesday. While there is not many impacts associated with this, for this discussion it is to note that this patter would keep consistent onshore flow present. The GFS and Canadian model have the upper level trough form into a closed low by Saturday morning just west of Seattle, moving southward into early next week. For now, there seems to be discrepancies in models.
Speaking of next weekend, that looks to be the next time the upper level pattern changes. Temperatures will warm slightly back to normal conditions for the end of the work week and next weekend. An additional benefit for constant onshore flow is that it will help to blow most if not all the smoke and haze remaining around the Bay Area farther inland to the East. Prevailing onshore winds will be featured through the week with afternoon seabreezes each day.
On the plus side, it will help maintain the marine layer and even deepen it slightly through midweek. Cold air advection behind it will drive temperatures at the surface to approximately 5 to 10 degrees below seasonal normal values for Tuesday and Wednesday around the Bay Area. A long wave trough develops over the Pacific and sets up along the California Coastline. At some point, it is expected on Monday that the radar eventually gets switched over to clear-air mode.Ī much quieter weather pattern is forecast for the work week. There remains a non-zero chance for a small pop-up shower today, given the higher precipitable water values and the influence of the local topography, but confidence is exceptionally low given how mostly stable the atmosphere has become. The upper level low associated with the higher moisture content will slowly leave the Bay Area and move eastward through the course of Monday. Winds have already switched around to the northwest providing additional onshore flow and cooling to the region. The radar remains in precip mode due to weak cells are are still present in the North Bay, moving northward out of the area. With the marine layer being below 1000 feet, Half Moon Bay has recorded visibility down to 4 statue miles, so patchy fog may be possible on the immediate coastline, but only expected to be in small pockets and not last too long after sunrise. Mid-level clouds remain in the area as the artifacts of the once tropical system. Temperatures remain mostly in the 60s overnight, with a few upper 50s along the coast and low 70s on the inland mountains and ridgetops. Slight warming forecast into next weekend.ĭISCUSSION. Cooling temperatures drop below seasonal normal values Tuesday and Wednesday. Lingering isolated showers are possible, but confidence is low. Cloud cover will slowly move eastward through Monday. Area Discussion for - San Francisco/Monterey Bay Area, CA (on/off) Help NOTE: mouseover dotted underlined text for definitionĪrea Forecast Discussion National Weather Service San Francisco Bay Area 433 AM PDT Mon Sep 12 2022