FXUS66 KMTR 151143 AFDMTR Area Forecast Discussion National Weather Service San Francisco CA 443 AM PDT Tue Oct 15 2024 ...New AVIATION, MARINE... .SYNOPSIS... Issued at 144 AM PDT Tue Oct 15 2024 Relatively quiet weather today as shortwave ridging continues to dominate. An inside slider event will result in critical fire weather conditions Thursday through the weekend. && .SHORT TERM... (Today and tonight) Issued at 144 AM PDT Tue Oct 15 2024 Shortwave ridging will result in near normal temperatures and a compressed/shallow marine layer through the day. The pattern begins to change tonight as troughing from a deep upper-level low in Canada and an associated cold front drops into the area. With no location expected to receive more than 0.05" inches of precipitation, this will do nothing to damper the critical fire weather conditions expected beginning Thursday. && .LONG TERM... (Wednesday through Monday) Issued at 144 AM PDT Tue Oct 15 2024 Confidence is increasing in an inside slider event as 60% of global ensemble members continue to trend towards a stronger, further west cutoff low solution, this is a reasonable worst case scenario. The biggest contributors to uncertainty at this time lie in the location and strength of the cutoff low. As the deep upper-level low digs into the Great Basin Thursday, strong northerly winds will develop across the region. Fortunately for fire weather concerns the wind on Thursday will not yet have an easterly component. This changes as the upper-level low becomes a cutoff low and digs further south Friday and winds become northeasterly/offshore, promoting rapid drying and compressional warming. Relative humidity recovery and retention will be poor Thursday through Saturday with Thursday night into Friday morning and Friday night into Saturday morning being the windiest timeframes. All of this to say critical fire weather conditions are going to be prevalent Thursday through Saturday. Extreme precautions should be taken and extreme fire safety should be exercised this week. && .AVIATION... (12Z TAFS) Issued at 425 AM PDT Tue Oct 15 2024 Patchwork stratus this morning, with the major Bay Area commercial terminals (SFO, OAK, SJC) enjoying a clear window. The North Bay is dealing with IFR and below visibility and ceilings which will persist through mid-morning. Winds will stay moderate across the area during the TAF period and may flip to offshore overnight. High clouds will begin to roll in towards the end of the TAF period, signaling a disturbance that will cause the marine layer to expand and should improve aviation weather conditions tonight. Vicinity of SFO...Somewhat surprisingly the 3 main Bay Area terminals are still VFR this morning. Guidance is still suggesting a sunrise surprise will form in the SF Bay and expand in all directions, even reaching as far as SJC. Since the guidance was too aggressive with the marine layer stratus so far this morning, the TAFs are more optimistic and keep all 3 sites VFR through the day. Otherwise the typical moderate to strong onshore winds will develop at SFO this afternoon. Looking beyond the TAF period, there is a good chance for near gale force gusts at SFO on Thursday afternoon and/or evening as a cold front pushes through. SFO Bridge Approach...Currently VFR, though a small cloud deck in the East Bay is expanding over the bridge and may impact the approach through the morning hours. Monterey Bay Terminals...LIFR ceilings at both MRY and SNS, with visibility dropping at both sites. Both sites will be in the junk through mid morning before a few hours of VFR conditions in the afternoon. An early return of IFR or worse stratus is expected before the sun sets. && .MARINE... (Today through Sunday) Issued at 425 AM PDT Tue Oct 15 2024 Rough to very rough seas continue across the exposed waters, with buoys reporting significant wave heights of 10 to 13 feet in a NW swell, and a fresh to strong NW breeze. Conditions will gradually improve through Wednesday as the long period swell abates. This reprieve will be short lived as conditions deteriorate again by Thursday. A stronger system will bring the possibility for gale force gusts and rebuild rough seas across the coastal waters. && .FIRE WEATHER... Issued at 149 AM PDT Tue Oct 15 2024 A Fire Weather Watch is in effect from 11 AM Thursday until 8 PM Saturday. Normal temperatures, excellent relative humidity recoveries, and onshore flow will keep fire weather concerns at ease through Wednesday. Fire weather concerns will be high Thursday through the weekend as an inside slider event comes to town. While fuels are near average, they are expected to dry out as the week progresses. Northerly winds will develop Thursday as a deep upper-level low digs into the Great Basin. As this digs further south and becomes a cutoff low, winds will become northeasterly/offshore. These winds will lead to rapid drying, compressional warming, poor relative humidity recovery and retention as low as 15%, and a nonexistent marine layer. The windiest timeframes will be Thursday night into Friday morning and Friday night into Saturday morning with winds largely on the order of 20-30 mph with gusts to 40 mph, isolated gusts to 50 mph across the highest terrain and ridgetops and through gaps and passes. && .BEACHES... Issued at 850 PM PDT Sun Oct 13 2024 Long period northwesterly swell of 13-17 seconds with wave heights approaching 10 feet will result in a moderate risk of sneaker waves across all Pacific Coast beaches through at least Wednesday. Large waves can sweep across the beach without warning, pulling people into the sea from rocks, jetties, and beaches. Beachgoers should always remember to observe the ocean for 20 minutes before relaxing near the water, keep your pets on a leash and away from the water, and never turn your back on the ocean. && .MTR WATCHES/WARNINGS/ADVISORIES... CA...Beach Hazards Statement through Wednesday evening for CAZ006-505- 509-529-530. Fire Weather Watch from Thursday morning through Saturday evening for CAZ006-502>504-506-508>510-512>518-528. PZ...Small Craft Advisory until 9 AM PDT this morning for Pigeon Pt to Pt Pinos 10-60 NM-Pt Arena to Pt Reyes 10-60 NM-Pt Pinos to Pt Piedras Blancas 0-10 nm. && $$ SHORT TERM...Sarment LONG TERM....Sarment AVIATION...Flynn MARINE...Flynn 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