, Issued at 154 PM PDT Mon Jul 20 2026 (This evening through Tuesday night)
Afternoon satellite and radar show clouds and showers streaming over the area from post tropical storm Elida. The showers are high based, meaning the bottoms of the the showers are around 5-8000 feet. At this elevation in summer months, the rain coming out of the showers typically evaporated before hitting the ground. Even so, with the forecast cycle, showers were added into much of the area with QPF limited to 0.01", which is generous. Really showers will be lucky to reach a trace.
The overall pattern is fairly interesting with a broad ridge over the western US, trying to flex into the west coast, but challenged by trough over the eastern Pacific. This trough is the exit route for post tropical storm Elida, riding up and over the edge of the ridge. This is where the complexities creep in. The strength of the ridge and trough are not static and models are trying to project them, but only offer about a 80% vision rate. Meaning, there is still error in the forecast. The error is showing up in the POP and QPF fields and trying to play with temps as well. As stated, the POP forecast has from NBM and other model guidance for the next 36 hours as Elida passes by. QPF will remain low, unless there is a wobble eastward of the remnant system. Models are showing nice vorticity bands (at 500, 700, and 850 mb) spinning off the remnant low, heading our way on Wednesday. This comes into play as it could provide a focus point for more intense showers, if there remains enough moisture in the area at that time, and right now that does not look probable. This will be something to watch as this system can still make a wobble. At this time there is no expectation of dry thunderstorms or even lightning. The depth of any convection just doesn't look deep enough to reach the hail growth zone needed to exchange charges and generate lightning. There would need to be a substantial shift in the pattern to find better areas of instability and even then, the system would need to intensify as undergoes extratropical transition, which it is showing no signs of. No mention of dry thunderstorms in the forecast.
Models continue to show Tuesday as the warmest day of the week with temps running about 5ish degrees above normal. However, the remnant low may provide more clouds than expected and cap temperatures to around normal. Confidence is high that in the wake of the remnant low temps will cool slightly, around 5ish degrees below normal. By the weekend the four corners high will try to press into the area again causing more warming.
Summary: Post tropical storm or remnant low Elida will continue to make the forecast challenging with respect to nearly all sensible weather elements. Keep an eye on an ever changing forecast.
..issued at 154 PM PDT Mon Jul 20 2026 (Wednesday through next Sunday)
In the wake of the remnant low confidence is high that temps will cool slightly, around 5ish degrees below normal, as troughing prevails. By the weekend the four corners high will try to press into the area again causing more warming. This will take us from a deeper marine layer for the second half of the workweek to a more compressed one for the weekend. The one thing to watch for as the trough makes it self known is onshore winds. Winds from the ocean on to land will increase each afternoon. Some key locations like Petaluma gap, Altamont, and through the Golden Gate will gust each afternoon. Strength will depend on where you are at.
(00z TAFS) Issued at 446 PM PDT Mon Jul 20 2026
VFR expected to prevail through the early evening hours with virga showers continuing to move across our area out ahead of the remnants of Elida. Little to no rainfall expected to reach the ground but winds could be erratic in vicinity of any passing showers. Where stratus ceilings develop later tonight into Tuesday morning, are expected to be IFR with similar clearing times as today.
Vicinity of SFO, VFR through late tonight with more confidence in KOAK developing IFR ceilings later tonight, and KSFO more likely to remain VFR through the forecast with a slight chance of IFR ceilings around sunrise, with both lifting by late mid-morning Tuesday.
SFO Bridge Approach, Similar as SFO.
Monterey Bay Terminals, IFR ceilings are expected to develop early evening before sunset and persist through late morning Tuesday with VFR for the remainder of the forecast period through Tuesday afternoon.
(today through Saturday) Issued at 1049 AM PDT Mon Jul 20 2026
Light to locally moderate northwesterly winds will prevail through midweek, becoming moderate Thursday into Friday. Slight to moderate seas will prevail. Tropical cyclone activity in the Eastern Pacific Ocean will spur several rounds of moderate period southerly swells; hazardous conditions from mixed seas may result. Instability from the remnants of the tropical cyclone will also bring a slight chance of convection that may bring showers as well as gusty and erratic outflow winds that would be result in hazardous conditions to small craft.
Ca, None. PZ, None.
