FXUS66 KMTR 150922 AFDMTR Area Forecast Discussion National Weather Service San Francisco CA 222 AM PDT Tue Oct 15 2024 ...New FIRE WEATHER... .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... (06Z TAFS) Issued at 1031 PM PDT Mon Oct 14 2024 Marine layer stratus is beginning to fill in across the Bay Area and widespread IFR to LIFR conditions are expected to persist beyond sunrise. A shallower marine layer could bring more visibility restrictions as well. Winds are light to gentle and will continue to weaken through the night. By late morning, moderate onshore flow will return to most terminals and persist through the afternoon. Vicinity of SFO...Stratus is beginning to develop along the SF peninsula and East Bay. Oakland is already reporting SCT clouds at 900 feet, but the VFR window will last longer at SFO. Both stations are expected to develop IFR ceilings in the next 4-6 hours. SJC has the best chance of dodging a ceiling, but it's still more likely than not. Stratus will clear out by late tomorrow morning with VFR to then persist through the remainder of the afternoon. Onshore flow is expected to persist overnight but will weaken to 5-10 knots. Gusty onshore flow returns tomorrow afternoon with gusts up to 22 knots currently expected. SFO Bridge Approach...More favorable than the surrounding areas at the moment, but ceilings are expected to impact the bridge approach by 12Z or so. Monterey Bay Terminals...IFR to LIFR ceilings are expected overnight, but there are some holes in the cloud layer. MRY is currently enjoying clear skies, but the clouds aren't too far away and I'll probably be chasing this TAF for the next few hours before the ceilings become more firmly entrenched. Otherwise winds will remain gentle overnight with a decent chance of fog developing in the morning. Conditions should return to VFR by mid morning, but there's still some uncertainty if and exactly when that will happen. && .MARINE... (Tonight through next Sunday) Issued at 1031 PM PDT Mon Oct 14 2024 Elevated seas continue across the outer waters with buoys reporting significant wave heights of 9 to 10 feet. Seas will remain elevated through Tuesday before abating slightly midweek. However, this will be short lived with seas expected to build again Thursday into Friday. Coastal jets have developed along the North Bay and Big Sur coasts with small craft advisories in effect into Tuesday. Long period northwesterly swell of 13-17 seconds leading to elevated surf conditions continues through Wednesday. Winds will be moderate to fresh out of the northwest through the middle part of the week. Towards Thursday, a low pressure system will bring widespread near-gale to gale force gusts across the entire 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 3 AM PDT early this morning for Pt Arena to Pt Reyes 0-10 nm. 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...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