FXUS66 KMTR 241838 AFDMTR Area Forecast Discussion National Weather Service San Francisco CA 1138 AM PDT Fri Apr 24 2026 ...New AVIATION... .KEY MESSAGES... Updated at 1205 AM PDT Fri Apr 24 2026 - Low potential for drizzle this morning across the Central Coast - Additional rounds of drizzle/light rain likely Saturday and Sunday - Below normal temperatures this weekend before a warming trend kicks off early next week && .UPDATE... Issued at 859 AM PDT Fri Apr 24 2026 Satellite imagery this morning is quite chaotic with a mix of low, mid, and high level clouds. Areas where stratus is visible appear to be socked in, which has impacted temperatures this morning putting them a few degrees behind their anticipated growth. Depending on if/when the clouds erode, the high temperature forecast could be off by a few degrees. && .SHORT TERM... Issued at 1205 AM PDT Fri Apr 24 2026 (Today and tonight) High clouds are streaming in with some lower level stratus making its way along the coast. There is some potential for fog tonight across the North Bay Valleys but confidence is mixed given the high level clouds moving in. Any fog that does develop should be relatively patchy due to the high level clouds minimizing how much radiational cooling is able to occur. If you do encounter fog on your morning commute remember to slow down, turn on your low beam headlights, and allow extra time to reach your destination. Broad upper level troughing persists across California as a deep upper level low remains fairly stationary over Canada/Montana/North Dakota. Within this broader trough, a weak upper level low looks to develop offshore of the Bay Area and move inland throughout the day. In terms of our rain chances, the current forecast grids show a less than 10% chance of precipitation today, but, some CAMs are showing isolated showers developing across the region Friday morning. The question then becomes how much moisture will actually be available today. The GFS shows a brief uptick in PWAT values from around 0.45" up to 0.55-0.65" Friday morning. The timing of this slight moisture flux matches well with when models like the NAM show some scattered showers over the Santa Lucia Range and the potential for drizzle across the rest of the Central Coast. Drier conditions are expected across the rest of the Bay Area so not anticipating drizzle to extend beyond coastal areas. If any rain is able to develop it is still unlikely for accumulations to be greater than a few hundredths to (maybe) a tenth of an inch across the Santa Lucia Range. Heading into the afternoon, we may start to see more radar returns across the marine environment but at this time we are not anticipating these showers moving inland or any accumulation from them. High temperatures on Friday will cool by around 4-5 degrees with highs dropping into the mid to upper 60s across the interior, 50s to 60s along the coast, and mid to upper 70s across the interior Central Coast. Diurnally breezy onshore winds continue with windiest conditions expected across the Salinas Valley and Altamont Pass region. && .LONG TERM... Issued at 1205 AM PDT Fri Apr 24 2026 (Saturday through Thursday) Heading into Saturday, we see slightly higher chances for precipitation as the upper level trough over California becomes more well defined and a second weak upper level low pushes into Southern California. This system will be accompanied by a stronger PWAT plume but the bulk of this moisture is aimed to our south. Model guidance does show several pulses of moisture moving through our CWA Saturday and Sunday which may support additional rounds of drizzle to light rain this weekend. Widespread drizzle is the most likely outcome with light rain possible in the Santa Lucia Range thanks to orographic uplift. Similar to Friday, precipitation totals will be minimal, ranging from a trace to a few hundredths of an inch. Portions of the higher terrain could see up to a tenth of an inch of rain between Saturday and Sunday. No major wind concerns with this system but locally gustier winds between 25 to 35 mph are expected across the higher elevations on Saturday. Broad upper level troughing continues through the remainder of the long term before upper level ridging looks to briefly rebuild Friday into early next weekend. Temperatures remain below normal this weekend with highs in the upper 50s to 60s. This is short lived with a slight warming trend kicking off Monday. Interior high temperatures will warm into the upper 60s to low 70s on Monday before warming into the low to mid 70s Tuesday through Thursday. Coastal high temperatures will remain relatively stable in the 50s to 60s through late next week. In the long run, CPC guidance shows a return leaning above normal temperatures and leaning above normal precipitation for the end of April into the beginning of May. Ensemble guidance has been showing the potential for another round of light, beneficial rain in this timeframe. This will be something to keep an eye on as we exit our rainy season and head into summer. && .AVIATION... (18Z TAFS) Issued at 1138 AM PDT Fri Apr 24 2026 Clouds this morning continue to erode leaving a mix of mainly MVFR to VFR conditions. Expect this trend to continue with most sites seeing a few hours of VFR cigs, the exception might be KHAF. Low clouds return tonight, which should bring widespread MVFR cigs, perhaps a few pockets of IFR. Drizzle will be possible along the coast, which could drop cigs and vis even more. Medium to high confidence in the forecast. Vicinity of SFO...Satellite this morning shows clods eroding east of SFO, while maintaining west of the airport. VFR conditions may prevail over the next few hours if clouds remain on the western half of the range ring. Otherwise expect conditions to bounce/flirt with MVFR and VFR conditions for the next few hours before becoming VFR for a brief period. A return of cigs is expected tonight and should have a similar trend tomorrow morning. Medium to high confidence in the forecast. SFO Bridge Approach...Similar to SFO. Monterey Bay Terminals...Monterey Bay has cleared out this morning, with pockets of cumulus remaining anchored to the terrain. Most sites will be VFR for the afternoon, with KMRY having lingering MVFR cigs for the next couple of hours. MVFR cigs return tonight along with the chance for some coastal drizzle. && .MARINE... (Today through Wednesday) Issued at 859 AM PDT Fri Apr 24 2026 Choppy seas will begin to gradually subside today and continue to do so into the weekend. Mainly moderate northwest winds continue through today and become moderate west to northwest breezes for the weekend. Drizzle and light rain remain in the forecast, favoring the southern waters and areas along the coast this weekend. && .MTR WATCHES/WARNINGS/ADVISORIES... CA...None. PZ...None. && $$ SHORT TERM...Kennedy LONG TERM....Kennedy AVIATION...KR MARINE...KR 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