992 FXUS66 KMTR 170238 AFDMTR Area Forecast Discussion National Weather Service San Francisco CA 738 PM PDT Wed Apr 16 2025 ...New UPDATE... .SYNOPSIS... Issued at 304 AM PDT Wed Apr 16 2025 Cooler temperatures again today. Otherwise, dry weather is expected through the forecast period. Warming trend begins tomorrow and continues into the weekend. In terms of the isolated thunderstorm threat for today, decreased chances to 10-14% which removed that from the point and click. See details below. && .UPDATE... Issued at 730 PM PDT Wed Apr 16 2025 Satellite shows stratus over the northern half of the region with mid-to-high level clouds entering the southern half of the region from the east. Lightning activity is diminishing across the state with the loss of daytime heating. The forecast remains on track with no updates needed at this time. Sarment && .SHORT TERM... Issued at 212 PM PDT Wed Apr 16 2025 (This evening through Thursday) Cooler and cloudy conditions exist over San Francisco area and for portions of the North Bay. There is some thinning of the clouds, but a solid feed continues thanks to a week circulation west of Pt Reyes. The broad picture shows some weak instability over the forecast area in the way of afternoon cumulus build ups over the hills. While the chances for thunderstorms have all but disappeared convection is firing over the Sierra. Latest ACARS for SFO and SJC show some MUCAPE, but it`s being crushed by bigger CIN. Some of the better moisture/instability is forecast to brush the Central Coast the next 12 hours, but still looking dry. For tonight: some mid-high level clouds are expected to filter over the region. Lower and at the surface, a robust marine layer is expected once again with some variations on depth from N to S. Similar to this morning actually, higher depth and cloud coverage for northern areas and less to the south. Thursday: clouds to start the day with a discontinuous marine layer. The longwave pattern shows the cut-off upper level low that has been spinning off the coast will move inland near LA as it transitions to an open wave. As this happens, another wound up upper low sweeps through the Great Basin. Locally, we`re looking for a more dry northerly flow with a slight warming trend. && .LONG TERM... Issued at 212 PM PDT Wed Apr 16 2025 (Thursday night through next Tuesday) To round out the work week and the start of the weekend we`ll see a notable warming trend. The interior upper low in the Great Basin will help establish a period of offshore flow Friday and Saturday. While not overly strong, it`s enough to assist with the warming trend due to downslope flow. High pressure also begins to build over the PacNW and drift into CA. Despite this setup the marine layer will compress, but may not completely go away. The warmer weather will hold into early next with dry zonal flow. Temperatures finally cool mid week with a weak trough developing over the West Coast. && .AVIATION... (00Z TAFS) Issued at 425 PM PDT Wed Apr 16 2025 MVFR stratus persists over much of the North Bay and the northern San Francisco Bay, as well as the southern reaches of Monterey and San Benito Counties; VFR everywhere else. Stratus will begin building across the coastal regions this evening and overnight with clearing through Thursday morning, with moderate confidence in timing. Stratus clearing is expected to be more comprehensive than that seen today, with the North Bay terminals clearing out rather late in the morning, compared to STS being well socked in today. Breezy southwesterly onshore winds will continue into the evening, turning northwesterly by the time they resume Thursday afternoon. Vicinity of SFO... Currently MVFR, monitoring a potential break in the clouds for at least temporary clearing over the terminal. Otherwise, expect MVFR ceilings to persist overnight and through late Thursday morning. Breezy west winds with gusts up to 25 knots will continue into the evening, diminishing overnight before resuming Thursday afternoon. SFO Bridge Approach... Less confidence in ceiling impacts for the southern end of the approach path. Otherwise similar to SFO. Monterey Bay Terminals... VFR through the evening with breezy onshore winds diminishing in the later evening hours. MVFR stratus returns overnight through Thursday morning. Ceilings might lift above MVFR criteria before the skies fully clear out early Thursday afternoon, as breezy onshore winds return. && .MARINE... (Tonight through next Monday) Issued at 425 PM PDT Wed Apr 16 2025 Moderate northerly winds dominate north of Point Reyes, but southerly winds persist elsewhere. Northerly winds will spread through the rest of the waters through Thursday and gradually build into the weekend. Rough seas persist in the northern outer waters through Thursday morning. Otherwise, slight to moderate seas persist into the weekend. && .MTR WATCHES/WARNINGS/ADVISORIES... CA...None. PZ...Small Craft Advisory until 3 PM PDT Thursday for Pt Arena to Pt Reyes 10-60 NM. && $$ SHORT TERM...MM LONG TERM....MM AVIATION...DialH MARINE...DialH Visit us at www.weather.gov/sanfrancisco Follow us on Facebook, X, and YouTube at: www.facebook.com/nwsbayarea x.com/nwsbayarea www.youtube.com/nwsbayarea