308 FXUS66 KMTR 062142 AFDMTR Area Forecast Discussion National Weather Service San Francisco Bay Area 142 PM PST Sun Nov 6 2022 .SYNOPSIS...Cool, unsettled weather conditions will continue through the first half of the week as a series of weather systems bring widespread rainfall and the potential for isolated thunderstorms. Conditions dry out late Wednesday into Thursday with colder overnight temperatures to follow. && .DISCUSSION...as of 01:41 PM PST Sunday...No significant changes to the forecast this afternoon as we have high confidence for an active weather pattern to continue through the first half of the week. While there has been a break in precipitation and cloud cover this afternoon, more widespread rain will approach the North Bay later this afternoon before spreading southward overnight. This is the result of a mid/upper level low pressure system just off of the British Columbia and Pacific Northwest coasts that will dig southward during the next 36 to 48 hours. As previously mentioned, light rain will develop over the North Bay by mid/late afternoon before gradually spreading southward across the Bay Area after sunset. This boundary will then move through the Central Coast after midnight and into early Monday morning. Rainfall with this system will again favor the coastal ranges as deep moisture advects inland across central California. Temperatures will also turn cooler with breezy winds at times making for a blustery start to the workweek. As the air mass aloft cools and becomes more unsettled, isolated to scattered rain showers and the potential for thunderstorms will exist Monday afternoon and evening. As the aforementioned mid/upper level trough digs farther south Monday night into Tuesday, another frontal boundary will do so as well while interacting with the increasingly unstable air mass and deeper moisture advection. This will result in another round of widespread moderate to locally heavy rainfall as the system eventually traverses the Bay area and Central coast into Tuesday morning. It is at this time that the potential for thunderstorms will be greatest with any convection likely producing brief heavy rainfall, lightning and small hail. It is also the timeframe in which we could see rainfall rates briefly exceed 0.50" which would result in nuisance flooding on area roadways and such. Breezy, locally gusty, and at times erratic winds are also expected with each frontal passage, yet widespread strong winds are not anticipated at this time. Lingering rain showers and possible thunderstorms then continue in wake of the frontal passage Tuesday night into Wednesday. Colder air will advect into the region as well with snow levels dropping to or below 3,500 feet. Thus, snow showers will be possible in the region's highest peaks. If timing of the coldest air mass and more widespread rain showers align, we could see modest snow accumulations in the peaks above the Big Sur coast (Santa Lucia Mountain Range). Drier conditions return by late Wednesday night into Thursday which will also allow for colder overnight/early morning temperatures. While much of the week daytime temperatures will struggle to warm out of the 50s, cloud cover will keep overnight temperatures from dropping much cooler than the 40s. Once sky conditions clear, we are likely to see more widespread 30s in the coldest interior spots both Thursday and Friday mornings. Looking a bit out to the extended, unsettled weather conditions look to return late in the week and into the upcoming weekend. However, confidence in the details remain low at this time. Stay tuned... && .AVIATION...As of 9:20 AM Sunday...For the 18Z TAFs. Widespread cloud cover across Central coast and a band of high clouds moving south from the North Bay into the Bay Area are the main focus. Monitoring STS to see when fog dissipates at the terminal, but otherwise all terminals should be VFR-MVFR for the day. Expect winds to be light to moderate, predominantly from the southwest. Ahead of the front, winds will pick up for around an hour prior to the frontal passage. Expect the front to arrive around 3-4z at the North Bay, around 5-6z for the Bay Area, and 9-11z for the Monterey Bay region. The front should clear most terminals by 11-12z, and expect clearing skies behind the front. Towards the end of the TAF period, models are showing some indications of scattered showers in the North Bay. Vicinity of SFO...VFR for the rest of the day. Winds will be breezy today, backing to a southwesterly flow in advance of the front, which will also bring rain and MVFR ceilings. Current best forecast is to have the front arrive around 4-5z, with clearing by around 10- 11z as winds gust to 20 knots. Winds will briefly turn to a westerly direction behind the front, before backing again to the southwest on Monday morning. SFO Bridge Approach...Similar to SFO. Monterey Bay...The day starts as VFR, with winds turning to the west-northwest within an hour or so. Although winds at the surface remain light, winds aloft will increase and shift to a more southerly direction ahead of the front. The first rain showers arrive at around 5z, but the worst weather is expected around 9-11z when the combination of breezy southerly to southeasterly winds and a stronger winds aloft in a continued westerly direction result in increased wind shear concerns, in addition to the rain and MVFR ceilings. The front should clear by 13-14z, with winds becoming light and lifting ceilings. && .MARINE...as of 09:22 AM PST Sunday...Light northwest winds will shift southerly this afternoon ahead of an incoming cold front. Fresh to strong breezes will develop along and behind the front, as winds veer to the northwest late Sunday. Moderate northwest swell persists throughout the weekend, before a much larger swell arrives early on Monday, which, combined with the breezy winds, will result in hazardous seas with wave heights reaching 14 to 16 feet. An unstable airmass settles in Monday as well, which will bring chances for thunderstorms throughout the waters. Winds and seas will continue to be elevated and hazardous through midweek. && .MTR WATCHES/WARNINGS/ADVISORIES... .Tngt...SCA...SF Bay from 9 PM until 3 AM SCA...Mry Bay from 9 PM SCA...Pt Arena to Pt Reyes 0-10 nm from 9 PM SCA...Pt Reyes to Pigeon Pt 0-10 nm from 9 PM SCA...Pigeon Pt to Pt Pinos 0-10 nm from 9 PM SCA...Pt Pinos to Pt Piedras Blancas 0-10 nm from 9 PM SCA...Pigeon Pt to Pt Piedras Blancas 10-60 nm from 9 PM SCA...Pt Arena to Pigeon Pt 10-60 nm && $$ PUBLIC FORECAST: RGass AVIATION: Dial MARINE: Dial 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