Issued at 900 AM PST Thu Jan 1 2026
The occluded front has moved across the region this morning producing widespread light to moderate rain. Rainfall over the past 24 hours has been greatest in the coastal ranges with 1.50-3.00" with Mining Ridge (in the Santa Lucia Range) picking up just over 5.00". Elsewhere, totals range from 0.25-1.50" across the remainder of Bay Area and Central Coast. As the mid/upper level cut of low moves onshore across the Central Coast here shortly, precipitation will be largely confidence to the coastal ranges through the remainder of the morning. There remains a slight chance for thunderstorms through early afternoon across the Central Coast and southern portions of the Bay Area, yet none have developed at this time. No changes anticipated this morning as the ongoing forecast remains on track.
RGass
, Issued at 1201 AM PST Thu Jan 1 2026 (Today and tonight)
Light rain continues across the Bay Area as the new year begins. While the total rainfall over the last 24 hours has been less than 1", the troposphere has become totally saturated. The PW was measured at 1.38" on the 00Z sounding. That's near the daily max, and in the top 0.3% of December soundings. The low level dry layer mentioned yesterday has been eliminated. In fact, the first dry layer is in the stratosphere. Despite the anonymously high moisture, rain rates were held in check by a lack of lift. We haven't had a front move through yet to wring out the sponge. That will change this morning as an occluded front moves across the Bay Area and Central Coast. This will increase the rain intensity, and brings a slight to moderate chance of thunderstorms. High resolution models show the best chance over the Central Coast and South Bay around 4-7 AM. After the front moves through showers will become more scattered and the clouds will lift and lighten. There is a second round of showers possible in the afternoon as the instability rises with warmer surface temperatures under the new cold air mass. A NAM point sounding at Salinas valid at 11 AM shows some instability (41 J/kg surface CAPE), winds backing with height(16kt 0-1km shear), and good low level moisture (91% LowRH). One limiting factor is the high freezing level (7,500+ ft). Most of the instability is in the warmer air below this level. This will limit the amount of ice in the clouds necessary for static electricity build up, significantly hurting the chances for thunderstorms to form after the front passes. The other issues is drier air behind the front. Most likely we will get a break after the morning push of stronger rain, with only isolated to scattered showers expected for the rest of the day and into Friday.
..issued at 1201 AM PST Thu Jan 1 2026 (Friday through Wednesday)
The mostly dry break now looks like it will continue through the majority of the day Friday before the main event of the week arrives Friday night. A strong cold front will quickly approach the coast, with southerly winds increasing to a strong breeze. These winds will pump a new round of tropical moisture, this time from the SW. With stronger winds and a lifting mechanism from FROPA, strong showers and thunderstorms are possible into Saturday morning. With the stronger forcing, these storms also have a marginal chance of hitting severe criteria. Even if storms don't produce damaging winds, the synoptic flow will likely bring some wind impacts across the cwa. Gusts should reach 40-50 mph along the coast and in higher terrain. While not quite as strong as last week, some tree damage and power outages are expected. Southerly winds also produce storm surge thanks to the Ekman Transport. This surge will combine with the ongoing king tides to bring exceptionally high tides on Saturday morning, in particular.
As the cold front passes, the 500 mb temperature will drop from around -16C to -23C. This will cause lapse rate to steepen, and could support deeper convection in the post frontal environment on Saturday. A reinforcing front is due on Sunday, bringing yet another round of heavier rain, but less damaging winds. While the rain intensity should start to lighten up next week, the pattern remains unsettled through the 8th or 9th.
(18z TAFS) Issued at 955 AM PST Thu Jan 1 2026
The main rain band has exited the Bay Area with scattered showers to persist through the remainder of today. Highest confidence in scattered showers continuing for the Bay Area this afternoon/evening while drier conditions prevail along the Central Coast. Moderate confidence that MVFR CIGs will gradually rise and VFR conditions will return this afternoon/evening. The limiting factor for the Bay Area will be the scattered showers moving through today which may result in temporary decreases in CIG heights. Temporary drops in visibility are possible if a shower moves directly over an airport. Winds strengthen and widespread rain returns towards the end of the TAF period as a stronger low pressure system arrives late in the day on Friday.
Vicinity of SFO, Scattered showers are allowing a mix of IFR to MVFR conditions to persist this morning. As showers become more scattered CIG heights should improve at SFO with MVFR to then persist through early this afternoon. Showers build in this evening into the overnight hours with ceiling heights expected to lower, becoming MVFR again, before VFR conditions return early Friday morning. Confidence is low to moderate in the CIG heights given that they look to be on the MVFR/VFR border tonight.
SFO Bridge Approach, Similar to SFO.
Monterey Bay Terminals, Scattered showers continue through early this afternoon with drier conditions expected through the rest of the TAF period. Rain returns after the end of this TAF period (late Friday). Winds strengthen early Friday morning with gusts to around 24 knots expected at SNS. Winds will be lower at MRY but will strengthen later in the day on Friday as the storm system approaches.
(today through Tuesday) Issued at 900 AM PST Thu Jan 1 2026
Scattered showers continue across the coastal waters through the rest of today. Winds have reduced across much of the waters but borderline small craft advisory conditions continue with gusts to around 21 knots. Hazardous conditions return overnight Thursday into Friday as winds rapidly strengthen to gale force. Gale force to near gale force winds will then continue through late Sunday before winds decrease early next week. Light to moderate rain and a slight chance of thunderstorms continues through the weekend. Rain chances and breezy winds continue into next week.
Issued at 900 AM PST Thu Jan 1 2026
Perigean spring tides (King Tides) will impact the region through Sunday. This is due to the combination of the full moon on 1/3, lunar perigee on 1/1, and perihelion on 1/3. In other words all three planetary bodies are lined up and close to each other. In addition to the high astronomical tide, the incoming low pressure system will bring strong southerly winds, generating some storm surge. The combination of these factors will bring minor to moderate coastal flooding to the low-lying areas near shorelines and tidal waterways during high tide through Sunday. At the San Francisco tidal gauge, high tide is expected to be 2.2 ft above normal at 9:34 AM Friday, 2.5 ft above normal at 10:26 AM Saturday, and 1.8 ft above normal at 11:18 AM Sunday. These predictions include up to 1.3 feet of storm surge that will enhance the astronomical tide and flooding threat. High tide varies up to 90 minutes earlier or later along the Pacific Coast and through the San Francisco Bay, respectively.
Ca, Coastal Flood Advisory until 2 PM PST Sunday for CAZ006-505-506- 508-509-529-530.
Wind Advisory from 1 PM Friday to 1 PM PST Saturday for CAZ006- 502>505-509-512-515>518-528>530.
PZ, Small Craft Advisory from 3 PM Friday to 3 AM PST Saturday for SF Bay N of Bay Bridge.
Small Craft Advisory until 9 PM PST this evening for Mry Bay.
Small Craft Advisory from 9 AM to 9 PM PST Friday for Mry Bay.
Gale Warning from 9 PM Friday to 3 AM PST Saturday for Mry Bay.
Small Craft Advisory until 3 PM PST this afternoon for Pt Arena to Pt Reyes 0-10 nm.
Small Craft Advisory from 3 AM to 9 AM PST Friday for Pigeon Pt to Pt Pinos 10-60 NM-Pt Arena to Pt Reyes 0-10 nm-Pt Reyes to Pigeon Pt 0-10 nm.
Gale Warning from 9 AM Friday to 3 AM PST Saturday for Pigeon Pt to Pt Pinos 0-10 nm-Pigeon Pt to Pt Pinos 10-60 NM-Pt Arena to Pt Reyes 0-10 nm-Pt Reyes to Pigeon Pt 0-10 nm.
Small Craft Advisory until 9 AM PST Friday for Pigeon Pt to Pt Pinos 0-10 nm.
Small Craft Advisory until 3 AM PST Friday for Pt Arena to Pt Reyes 10-60 NM-Pt Pinos to Pt Piedras Blancas 0-10 nm.
Gale Warning from 3 AM Friday to 3 AM PST Saturday for Pt Arena to Pt Reyes 10-60 NM-Pt Pinos to Pt Piedras Blancas 0-10 nm.
