The Headline:
A powerful storm flooding northern California will make its way south through the Central Coast later Friday PM into Saturday. More rain Sunday through Tuesday is in the forecast. This will be more significant than any other event we've had thus far this season, but it will not produce local rain amounts like it is producing in NorCal. Local rainfall Friday through Tuesday .50-3" is possible and is location-dependent (more later in this story).
Tonight and Thursday:
Expect fair skies and dry weather through Thursday as a weak ridge of high pressure dominates the region. Offshore flow will remain mild, limiting strong canyon winds but keeping humidity low in the interior areas, which raises some fire weather concerns.
Skies will range from mostly clear to partly cloudy due to mid- and high-level clouds streaming in from a strong storm system far to the north. Temperatures will climb slightly each day:
- Highs Thursday: Slightly warmer, with valley and inland areas exceeding seasonal averages, while coastal areas remain cooler due to the influence of sea breezes.
Friday:
The weather begins transitioning toward a cooler and wetter pattern. The ridge will move east, allowing a powerful storm system currently impacting the Pacific Northwest to shift southward. Onshore flow will develop later in the day, increasing cloud cover north of Point Conception.
- Rain Timing:
- A slight chance of rain will emerge Friday afternoon in northwest San Luis Obispo County but chances increase through the evening.
- Temperatures will cool in most areas.
Long Term (Saturday - Tuesday):
Weekend Storm System:
This weekend will feature the Central Coast’s first major storm of the season, bringing cooler temperatures, widespread cloud cover, and periods of rain. The storm will be driven by a strong jet stream and a moisture plume though the system lacks consistent southerly flow that typically enhances rainfall totals.
Rain Timing:
The storm will bring two main frontal waves:
1. First Wave: Arriving Friday evening into Saturday, with lighter rainfall.
2. Second Wave: Expected late Sunday into Monday, potentially stronger with better upslope flow, leading to higher rainfall amounts in mountain and foothill areas.
Rainfall Amounts:
- North of Point Conception:
- Northwest San Luis Obispo County: 2 to 3 inches possible.
- Other areas: 0.75 to 1.5 inches.
- South of Point Conception:
- Coastal and valley areas: 0.75 to 1.5 inches.
- Enhanced rainfall is possible along the south-facing slopes of the Santa Ynez Mountains.
Ensemble models suggest variability, with some showing totals as high as 2–4 inches, especially in isolated areas, though these scenarios remain less likely.
Temperatures:
The storm will bring a noticeable drop in temperatures:
- Highs will generally remain in the upper 50s to mid-60s through the weekend and into early next week.
Snow Potential:
This is a warm system, so snow levels will remain above 7,000 feet through the weekend. As colder air filters in Monday and beyond, snow levels may drop to 5,000–6,000 feet, but precipitation will likely taper by then, minimizing snow impacts.
Looking Ahead:
There’s a chance of a third, colder storm arriving late next Tuesday or Wednesday, potentially bringing lower snow levels and additional rain. Stay tuned for updates as this dynamic system evolves.
