Area Forecast Discussion
Issued by NWS San Francisco Bay Area, CA
Issued by NWS San Francisco Bay Area, CA
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346 FXUS66 KMTR 180425 AFDMTR Area Forecast Discussion National Weather Service San Francisco CA 925 PM PDT Tue Sep 17 2024 ...New UPDATE... .SYNOPSIS... Issued at 1233 PM PDT Tue Sep 17 2024 The next weather system will bright light rain to parts of the region on Wednesday and then taper off from north to south on Thursday. A warming and drying trend is expected by this upcoming weekend and into early next week. && .UPDATE... Issued at 924 PM PDT Tue Sep 17 2024 At this hour, mid level clouds are passing through the region ahead of our next cold front. As a result, skies are overcast across the area, and temperatures are on the cool side sitting in the mid 50s for most locations. Temperatures are running 1-2 degrees cooler compared to this time yesterday in the interior regions, and generally 1-2 degrees warmer around the bays and along the immediate coastline. Chances of light rain are still expected for early Wednesday morning. Most regions will only see a few hundredths of rainfall, with the wettest locations (generally higher elevations) only seeing around a tenth. Isolated peaks may see amounts closer to 0.2" at most. All for now. && .SHORT TERM... (This evening through Wednesday) Issued at 1233 PM PDT Tue Sep 17 2024 Another upper level low will approach the coast tonight and move across on Wednesday brining generally light rainfall to the region. Coastal drizzle will be possible ahead of the system tonight but transition to light rain showers throughout the day tomorrow. By tomorrow afternoon, the greatest potential for thunderstorms will be across the North Bay with a ~15% (a non-zero chance elsewhere). Rainfall amounts are expected to be light, not amounting to more than 0.10" in most locations expect for locally higher totals in the coastal ranges or where any stronger showers develop. Lastly, winds will not be a concern with this passing system with only 15-25 mph onshore gusts. && .LONG TERM... (Wednesday night through next Monday) Issued at 1233 PM PDT Tue Sep 17 2024 Rain showers will linger into Thursday morning across the Central Coast, tapering off from north to south throughout the afternoon and ending by the evening. Friday looks to remain cool as the mid/upper level trough begins to exit the region but still having an influence. Temperatures over the weekend will trend upward towards seasonal averages. The marine layer also looks to return as a result with night and morning low clouds likely into next week. Low clouds will the retreat to the coast by the afternoon each day throughout the week. && .AVIATION... (00Z TAFS) Issued at 526 PM PDT Tue Sep 17 2024 Currently a mixed bag across the board with both low clouds and high clouds moving into the region. Another early season cold front will traverse into the area tomorrow bringing with it chances for precipitation and thunderstorms. The TAFs were constructed with a four hour timeframe where probabilities of -SHRA were highest, -DZ is possible preceding and succeeding that timeframe. Ceilings will be transient between MVFR and VFR through the TAF period. There is up to a 15% chance for thunderstorms tomorrow; however, confidence was not high enough in location and/or timing to definitively include in the TAFs at this time. Vicinity of SFO...Currently MVFR with westerly flow. MVFR ceilings have made an early appearance and will likely impact the terminal through tomorrow morning. Westerly winds will prevail through the TAF period. Best timeframe for precipitation (-SHRA) is 14Z-18Z with -DZ possible preceding or succeeding that timeframe. SFO Bridge Approach...Similar to SFO. Monterey Bay Terminals...Currently MVFR with northwesterly flow at MRY and VFR with northwesterly flow at SNS. Guidance/models are suggesting two distinct time frames for precipitation with the first being tonight and the second being tomorrow morning. SNS will deteriorate to MVFR early this evening and return to VFR by tomorrow afternoon with MRY slated to remain MVFR through the TAF period. && .MARINE... (Tonight through next Monday) Issued at 526 PM PDT Tue Sep 17 2024 Gentle northwesterly winds with the occasional moderate gust persist through Wednesday morning. Hazardous seas return by late Wednesday as a cold front arrives and brings moderate to fresh NW winds and rough seas to the outer coastal waters. Strong gusts are possible over the far northern outer waters beginning Thursday through the weekend. && .MTR WATCHES/WARNINGS/ADVISORIES... CA...None. PZ...None. && $$ SHORT TERM...RGass LONG TERM....RGass AVIATION...Sarment MARINE...Kennedy Visit us at www.weather.gov/sanfrancisco Follow us on Facebook, Twitter, and YouTube at: www.facebook.com/nwsbayarea www.twitter.com/nwsbayarea www.youtube.com/nwsbayarea