Area Forecast Discussion
Issued by NWS San Francisco Bay Area, CA
Issued by NWS San Francisco Bay Area, CA
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612 FXUS66 KMTR 182032 AFDMTR Area Forecast Discussion National Weather Service San Francisco CA 132 PM PDT Wed Sep 18 2024 ...New SYNOPSIS, SHORT TERM, LONG TERM... .SYNOPSIS... Issued at 131 PM PDT Wed Sep 18 2024 Isolated to scattered rain showers continue into this evening, tapering off from north to south gradually through Thursday afternoon. A warming trend is on tap for by this upcoming weekend and into early next week with temperatures rebounding to near seasonal averages. && .SHORT TERM... (This evening through Thursday) Issued at 131 PM PDT Wed Sep 18 2024 An upper level low remains off of the North Bay coast at this hour and will continue to drop southward throughout the day before moving onshore over the Central Coast tonight/tomorrow. As such, much of the rainfall from this system will remain light and some locations may not see any rainfall at all! There remains a slight chance of thunderstorms across the North Bay this afternoon before the thunderstorm threat focuses on the southern portion of the Central Coast on Thursday. The threat generally remains less than 15% however, so confidence of thunderstorm development remains low. Wrap around moisture from the system as it pushes inland will result in the continued rain chances (and low end thunderstorm chances) into tomorrow over the Central Coast but the North Bay and Greater San Francisco Bay Area are expected to be dry beyond late this evening. Any thunderstorms that to develop will have the potential to produce isolated, brief downpours. Temperatures both today and tomorrow will be 5-15 degrees below seasonal averages. && .LONG TERM... (Thursday night through next Tuesday) Issued at 131 PM PDT Wed Sep 18 2024 Friday afternoon will still be below normal across the region as the upper level trough begins to push further inland. The warm-up doesn`t begin until Saturday with near to slightly below normal temperatures. Sunday and into early next week is when temperatures are expected to be slightly above average as high pressure from the eastern Pacific begins to build inland. 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... (18Z TAFS) Issued at 1112 AM PDT Wed Sep 18 2024 Approaching showers have slowed down slightly but are expected to reach the Bay Area by late this morning and continue into the afternoon. Currently a mix of mid-level clouds and MVFR CIGs with VFR conditions to return during the afternoon/evening. Any showers that do directly impact airports may result in temporary decreased visibility and lowered ceilings. Confidence remains low on inclusion of thunderstorms in TAFs. For all sites except STS, there is a less then 8% chance of thunderstorms. For STS, thunderstorm chances reach 10-12% beginning early this afternoon through the evening. Shower chances decrease at all airports except MRY and SNS beginning this evening with MVFR CIGs expected to return overnight. Light to moderate southwesterly winds continue into the afternoon before becoming more northwesterly after cold frontal passage later this afternoon. Vicinity of SFO...Scattered showers will arrive within the next few hours. Any precipitation that reaches the surface will generally be light but if a stronger shower moves directly over the airport visibilities may temporarily decrease. A low chance (~5%) of thunderstorms continues for SFO through this afternoon. Confidence is too low to include in TAFs but will continue to monitor as showers start to approach the SF Peninsula. Moderate west to northwest winds continue with winds weakening slightly overnight. SFO Bridge Approach...Similar to SFO. Monterey Bay Terminals...Scattered showers are expected to move through the Central Coast through late this evening. Low chance of thunderstorms (~4-5%) continues through this evening but confidence remains too low to include thunderstorms in TAFs. MVFR to IFR CIGs are expected to return later this evening with an early return around 02-03Z. Low to moderate confidence on timing of transition from MVFR to IFR CIGs overnight. Moderate northwesterly winds are expected during the day with lighter, variable winds overnight. && .MARINE... (Today through Monday) Issued at 924 AM PDT Wed Sep 18 2024 Northwesterly winds will become gusty across the outer waters by late Wednesday. Seas will be moderate, building to become rough in the outer waters by Thursday. Unsettled conditions will continue over the outer waters through the weekend. Showers continue over the coastal waters through this afternoon. There is up to a 12% chance for thunderstorms in the mid morning which could produce lightning, locally heavy rainfall, locally gusty winds. && .MTR WATCHES/WARNINGS/ADVISORIES... CA...None. PZ...Small Craft Advisory from 3 PM Thursday to 3 PM PDT Friday for Pt Arena to Pt Reyes 10-60 NM. && $$ SHORT TERM...RGass LONG TERM....RGass AVIATION...Kennedy 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