Area Forecast Discussion
Issued by NWS San Francisco Bay Area, CA
Issued by NWS San Francisco Bay Area, CA
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333 FXUS66 KMTR 202044 AFDMTR Area Forecast Discussion National Weather Service San Francisco CA 144 PM PDT Fri Sep 20 2024 ...New SYNOPSIS, SHORT TERM, LONG TERM... .SYNOPSIS... Issued at 143 PM PDT Fri Sep 20 2024 Warming trend continues through the weekend into early next week, with moderate HeatRisk possible inland Monday and Tuesday. && .SHORT TERM... (This evening through Saturday) Issued at 143 PM PDT Fri Sep 20 2024 A warming trend was expected to start today as an upper level low moves off to the east, but you wouldn`t know it from the 24 hour temperature trends, which have not shown much warming from the same time yesterday, and if anything, have ran up to five degrees cooler across the valleys. The extensive stratus deck this morning and the continuing onshore flow may have kept things cooler than what was earlier forecast. Have bumped today`s high temperatures across the inland valleys down to account for this. The current forecast calls for high temperatures today to rise into the upper 70s to the lower 80s across the inland valleys, around the mid 60s to the mid 70s along the Bayshore, and into the upper 50s to mid 60s along the Pacific coast. Some more warming is expected tomorrow with the warmest inland regions scraping into the low 90s. Stratus has retreated back to the coastal regions and the Monterey Bay region, where the clouds are expected to persist through the day before the stratus extends inland this evening and overnight. && .LONG TERM... (Saturday night through next Thursday) Issued at 143 PM PDT Fri Sep 20 2024 The fringes of an upper level ridge will impact the state through the weekend into early next week, with the main impact being a warming trend across the region. By the early part of next week, high temperatures should peak into the mid to upper 90s across the inland valleys and the upper 60s to the mid 70s across the Pacific coast. Model ensemble clusters continue to show poor consensus on the upper level pattern towards the rest of the next week. However, CPC outlooks suggest a lean towards temperatures above seasonal averages and precipitation below seasonal averages into the first several days of October. && .AVIATION... (18Z TAFS) Issued at 1057 AM PDT Fri Sep 20 2024 Mix of IFR and MVFR CIGs expected to gradually clear by late morning. Stratus has started to recede from inland locations (LVK, SJC, SFO) with all sites across the Bay Area to clear by 19-20Z. Across the Central Coast, a healthy feed of stratus from Monterey Bay may keep ceilings around longer with clearing tentatively anticipated to occur around 20Z. Stratus will return again tonight but is not expected to be quite as widespread. Confidence is low to moderate that stratus will reach LVK and SJC overnight with current thinking that clouds will be predominantly scattered and any lower ceilings that do form will only be temporary in nature. Elsewhere, stratus is expected to return slightly later tonight with most Bay Area sites seeing returns between 06-10Z. Light, locally variable winds continue through the remainder of the morning before more moderate generally west to northwest winds return during the afternoon. Vicinity of SFO...VFR to persist through the afternoon/evening before MVFR CIGs return overnight. CIGs look to stay on the MVFR-IFR border but the NBM and GLAMP are in agreement that CIGs should stay MVFR. Stratus is expected to return later tonight around 10Z compared to around ~09Z yesterday. Light northwest winds are expected to strengthen by early this afternoon with moderate west to northwest winds persisting through the remainder of the day. SFO Bridge Approach...Similar to SFO. Monterey Bay Terminals...A healthy feed of stratus continues to move into SNS and MRY which is pushing back the timing of clearing. Moderate confidence that stratus will clear around 20-21Z for at least a few hours this afternoon. The main uncertainty revolves around how long stratus will continue feeding in from the Monterey Bay and if a scenario similar to yesterday, where clearing did not really happen, will occur. Assuming stratus does clear, an early return around 00-01Z is expected at both MRY and SNS with MVFR-IFR CIGs persisting through the rest of the TAF period. Moderate northwest winds persist during the day before weakening overnight. && .MARINE... (Today through Wednesday) Issued at 912 AM PDT Fri Sep 20 2024 Moderate northwesterly winds continuing through Monday, then decrease to become gentle towards Tuesday. Seas will continue to build through the weekend, with wave heights up to 13 feet in the far northern outer waters as large, and shorter period northwesterly swell continues to move into the waters. Seas begin to abate Tuesday through the end of the forecast period. && .MTR WATCHES/WARNINGS/ADVISORIES... CA...None. PZ...Small Craft Advisory until 9 PM PDT Saturday for Pt Arena to Pt Reyes 10-60 NM. && $$ SHORT TERM...DialH LONG TERM....DialH AVIATION...Kennedy MARINE...AC 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