FXUS66 KMTR 151752 AFDMTR Area Forecast Discussion National Weather Service San Francisco CA 1052 AM PDT Tue Oct 15 2024 ...New AVIATION, MARINE, BEACHES... .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... (18Z TAFS) Issued at 1050 AM PDT Tue Oct 15 2024 Mostly VFR conditions across the region expect near-term around the Monterey Bay Terminals which are IFR/LIFR expected to clear by late this morning. Onshore winds increase this afternoon and will diminish by late evening. 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. The Monterey Bay Terminals are most likely to see the return of low clouds late this evening and persist into the overnight. Vicinity of SFO...VFR, moderate to high confidence. Light and variable winds this morning will increase and become onshore by this afternoon. Wind speeds diminishes overnight, yet are expected to remain out of the west-northwest as an incoming trough approaches from the northwest. This should allow conditions to remain VFR through the TAF period. SFO Bridge Approach...Similar to SFO. Monterey Bay Terminals...IFR/LIFR conditions this morning improving to VFR through the evening. Winds will increase out of the west- northwest this afternoon before diminishing by early evening. Low clouds are expected to return early this evening as a moderate marine layer remains in place with conditions lowering to IFR/LIFR, medium confidence. && .MARINE... Issued at 1050 AM PDT Tue Oct 15 2024 Rough to very rough seas continue to subside across the exposed waters with fresh to moderate 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 1050 AM PDT Tue Oct 15 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. Red Flag Warning from 11 PM Thursday to 5 PM PDT Saturday for CAZ006-502>504-506-508>510-512>518-528. PZ...Small Craft Advisory until 3 AM PDT Wednesday for Pt Pinos to Pt Piedras Blancas 0-10 nm. && $$ SHORT TERM...Sarment LONG TERM....Sarment AVIATION...RGass MARINE...RGass 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