Swell Matrix

Area Forecast Discussion

National Weather Service San Francisco Bay Area

905 pm PDT Sat Jun 24 2017


Typical Bay Area weather pattern expected through the weekend and into next week. Expect areas of night and morning low clouds and fog followed by sunny afternoons. Temperatures will be near seasonal averages.


As of 9:05 PM PDT Saturday, A weak upper level disturbance moving from south to north up along the California coast generated a line of showers over our southern coastal waters late this morning and afternoon, with isolated showers extending over Monterey county as well. In addition, an isolated thunderstorm developed over the coastal waters west of Monterey Bay around 2:30 this afternoon. Current radar shows that all shower and thunderstorm activity has ended as the disturbance moves north of our area. No additional convective activity is expected in our area.

An upper trough is currently located offshore along 130W. This trough is forecast to track to the ENE and across northern California on Monday. As it approaches the coast, expect continued deepening of the marine layer and thus a continuation of our inland cooling trend through Monday. In fact, by Monday high temperatures for inland areas are forecast to be about 5 degrees cooler than normal, a big difference from the triple-digit heat that occurred during our recent prolonged heat event.

Temperatures are forecast to gradually warm from Wednesday through Friday of next week as the upper trough moves off to our east and is replaced by an upper ridge. However, temperatures are only expected to climb to levels near or slightly warmer than normal.

No precipitation is expected through the forecast period except perhaps for patchy night and morning coastal drizzle from the deep marine layer over the next few days.


As of 4:50 PM PDT Saturday, For 00Z TAFs, Onshore flow at the surface along with a 1600 ft marine layer similar to last night will result in similar timing for the return and the extent of the stratus tonight. Meanwhile high clouds streaming in with the upper level southerly winds will continue to move across the region through tonight.

Vicinity of KSFO, VFR conditions will prevail through this evening with cigs anticipated to return to KOAK around 04z and over KSFO around 08z tonight. Low clouds will scatter out around 15z to 17z Sunday morning. Moderate west winds around 15 to 20 kt will persist through this evening then ease to around 10 kt overnight.

SFO Bridge Approach, Similar to KSFO.

Monterey Bay Terminals, MVFR cigs will return early to Monterey area terminals this afternoon and will rapidly lower to IFR by 02z and LIFR around 04z. Low clouds will scatter our around 17z Sunday morning. Light west winds.


As of 8:35 AM PDT Saturday, Generally light northerly winds are expected this afternoon across the waters with higher wind speeds along the Big Sur coast. Wave heights and swell are forecast to decrease through the weekend.

Watches, Warnings, Advisories

Tonight, sca, pt pinos to pt piedras blancas 0-10 nm sca, SF Bay until 9 pm

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