, Issued at 1238 PM PST Wed Dec 24 2025 (This evening through Thursday)
The skies have cleared better than expected today giving us a short, but remarkably nice break between last night's wind storm and the upcoming system. The initial round of showers could reach the Santa Cruz/San Mateo coast as early as 3 PM. This is a prefrontal trough that won't bring the primary impacts expected overnight, but is currently producing thunderstorms over the coastal waters that could survive until landfall. With the bonus sunshine, temperatures are climbing higher than expected and that's translating to a better convective environment. Santa Rosa has been under clear skies since the Sun rose this morning and is currently reporting a temperature of 61 degrees, well above the 56 we had for the maximum today. This extra surface heating will play a role in the instability going into the evening hours. The environment ahead of tonight's storms look pretty good for thunderstorms and even tornadoes. The 18Z RAP shows the following parameters at SFO compared to the preferred value for supercell tornadoes in parentheses. 0-1km shear: 40 kts (20), MLCAPE: 209 J/kg (1500), Significant Tornado Parameter: 0.3 (1.0), MLCIN: -2 (>-25), Effective Storm Relative Helicity: 242 m2/s2 (150), Effective Bulk Wind Difference: 44 kts (40). This is a high-shear, low CAPE set-up, but the increased surface temperature and high dew points from last night's rain are helping the surface based convection chances. In fact, our next shift just walked in and one of the meteorologists said it feels like Kansas in May out there.
The main impacts are expected through the overnight hours and will be similar to last night. The winds may be a notch lower, but the severe thunderstorms chances are a notch higher. The other difference compared to last night is how much longer the winds will linger into the following day. The parent low pressure system will not push inland, but rather linger off the coast while gradually weakening. This will keep southerly winds elevated through the day Thursday, while pushing through a couple bands of showers. The peak of the impacts are still expected in the middle of the night, but we won't get the quick reprieve that we saw this morning. It will still be breezy while the kids try out their new bikes and basketballs Christmas morning. Scattered showers will be a threat through the day.
..issued at 1238 PM PST Wed Dec 24 2025 (Thursday night through next Tuesday)
Starting in the early morning Friday, winds and shower activity will gradually decrease as the low pressure system offshore opens up into a trough and moves into northern Oregon. The associated surface trough axis will move across the Bay Area Friday evening. This will finally flip the winds back to northerly, bringing drier, cooler weather for the weekend. The 1000-500 mb thickness actually increases this weekend, with the cooling coming mainly from enhanced radiation during in the cloudless nights. Sunday through Tuesday look particularly calm, clear and cool as a 500 mb ridge sets in. The next troughing pattern looks probable on the 1st or 2nd, just in time for King Tides. There's no strong signal for major impacts yet, but the CW3E ECCC AR Activity tool shows higher than normal chances for atmospheric rivers through the first half of January.
(00z TAFS) Issued at 352 PM PST Wed Dec 24 2025
VFR prevails, however radar and satellite imagery show widely scattered showers across the forecast area including recent isolated thunderstorms approaching the coastal waters from the southwest. A strengthening low pressure system will approach far northern California and the Pacific Northwest tonight through Christmas Day/Night. As mentioned in the previous discussion, southerly winds will re-intensify to similar speeds last night. Expect low level wind shear developing through the evening and overnight, winds easing later Christmas Day. The frontal system will result in rain showers, occasionally heavy, including a chance of thunderstorms across the area tonight through Christmas Day/Night.
Vicinity of SFO..VFR then MVFR-IFR developing mid evening with showers and a chance of a thunderstorm. Showers and a chance of a thunderstorm continue tonight and Christmas Day. Southeasterly wind generally continuing ahead of the next strong frontal system arriving later tonight and early Christmas Day. Southeasterly wind increasing upwards to around 35 knots by 05z-09z and continuing to 20z Christmas Day, easing later in the day.
SFO Bridge Approach, Similar to SFO.
Monterey Bay Terminals, VFR then MVFR developing mid to late evening with showers and a chance of a thunderstorms. Showers and a chance of a thunderstorms continue tonight and Christmas Day. Southeasterly winds continuing ahead of the next strong frontal system arriving later tonight and early Christmas Day; gusts upwards 30-35 knots, easing later in the day.
(tonight through next Monday) Issued at 324 PM PST Wed Dec 24 2025
, HAZARDOUS MARINE CONDITIONS CONTINUE INTO EARLY FRIDAY, Moderate southeast breezes across the coastal waters will gradually re-intensify to sustained gales from the south by midnight. These dangerous winds will be accompanied by a good chance for thunderstorms and possible waterspouts through the early morning hours Thursday. Seas will rebuild to very rough from the choppy wind waves. These hazardous seas will linger through Friday, reinforced by a moderate westerly swell. If your vessel is not able to handle these conditions return to port or seek protected waters as soon as possible.
Issued at 325 PM PST Wed Dec 24 2025
A Beach Hazards Statement has been issued for the coast through 4AM Friday. The main concerns include:blowing and drifting sand and wind waves up to 20 ft. The drifting sand and increased sea spray will also result in poor visibilities, affecting water rescues. Increased coastal erosion will be possible as well.
Ca, Flood Watch through Friday evening for CAZ006-502>506-508>510- 512>518-528>530.
Beach Hazards Statement through late Thursday night for CAZ006- 505-509-529-530.
High Wind Warning from 8 PM this evening to 10 AM PST Thursday for CAZ006-503-505-509-517-528>530.
Wind Advisory from 8 PM this evening to 10 AM PST Thursday for CAZ502-504-506-508-510-512>516-518.
PZ, Gale Warning until 3 AM PST Friday for Mry Bay-Pigeon Pt to Pt Pinos 10-60 NM-SF Bay N of Bay Bridge.
Storm Warning until 3 AM PST Friday for Pigeon Pt to Pt Pinos 0- 10 nm-Pt Arena to Pt Reyes 0-10 nm-Pt Arena to Pt Reyes 10- 60 NM-Pt Pinos to Pt Piedras Blancas 0-10 nm-Pt Reyes to Pigeon Pt 0-10 nm.
