UPDATE
Issued at 932 PM PDT Wed Sep 11 2024

Winds at sea level and lower elevations are for the most part continuing to ease through the evening, the exceptions are in the gaps, a few areas on hill tops and mountain tops where onshore winds are still gusty at this hour. The SFO-SAC pressure gradient still predominates but is more moderate since decreasing to 3.4 mb at 9 pm.
Gale warnings over the southern SF Bay and southern inner coastal waters were lowered to small craft advisories for tonight and Thursday morning.

SHORT TERM
(This evening through Thursday)
Issued at 137 PM PDT Wed Sep 11 2024

A cold front currently draped off the West Coast will plunge into Northern California this afternoon bringing mild and windy conditions. Widespread wind gusts of 30 mph are expected this afternoon and evening with wind gusts of 45+ mph expected through gaps, passes, and other favorable locations like SFO and the Salinas Valley. While the overall fire threat is on a downward trend due to lower temperatures and higher relative humidities, fuels still remain critically dry with large fires still possible.
Therefore, any fire that starts will have no problem spreading and strong winds will only exacerbate that. Winds will decrease tonight as the upper-level trough axis swings out and low- amplitude upper-level ridging builds in. In addition, winds in Napa and Sonoma Counties will become northerly/offshore during the overnight and morning hours until the sea breeze prevails in the afternoon.

LONG TERM
(Thursday night through next Tuesday)
Issued at 137 PM PDT Wed Sep 11 2024

Friday will be the warmest day of the week as a weak, low- amplitude upper-level ridge builds into place, acting as a break in between troughs more than anything. Northerly/offshore flow will continue during the overnight and morning periods through Saturday morning in Napa and Sonoma Counties. Upper-level troughing will start to take shape off the West Coast Saturday promoting cooler conditions and onshore flow. Confidence is increasing in an upper-level low and associated cold front sweeping across the region Sunday bringing below normal temperatures and renewed chances for measurable rainfall. This unsettled pattern will persist into next week as an upper-level trough develops on the heels of the upper-level low.

AVIATION
(06Z TAFS)
Issued at 1056 PM PDT Wed Sep 11 2024

Another mixed bag of VFR and MVFR-IFR conditions tonight. Stratus is already building up along the coastline and extending into portions of the Bay Area and Central Coast. Winds continue to ease overnight with stronger gusts between 25-35 knots expected to drop off around 08-09Z. Moderate confidence that MVFR-IFR CIGs to fog will persist along the coast through late tomorrow morning. Low to moderate confidence as to how long stratus will persist at inland sites overnight with guidance indicating some potential for stratus to become patchier/more localized after 09-12Z. Ensemble guidance is indicating that stratus may persist through late morning at SFO and OAK but confidence remains on the lower end. By late tomorrow morning, VFR is expected to return to all sites with moderate winds redeveloping during the afternoon. Stratus is expected to return along the coast by late tomorrow evening.

Vicinity of SFO...Stratus is currently moving in to SFO and OAK with MVFR-IFR CIGs expected. Pushed back stratus clearing to closer to 12Z for SFO but confidence remains low to moderate given uncertainty in a second frontal boundary arriving overnight. Gusty west winds persist until 08-12Z when winds start to drop off more substantially. Moderate west to northwest winds between 10-15 knots and gusting up to 25 knots return tomorrow during the day before weakening overnight.

SFO Bridge Approach...Similar to SFO.

Monterey Bay Terminals...MVFR-IFR CIGs expected to prevail with temporary LIFR CIGs possible. Currently not expected major impacts to visibility at MRY and SNS but some reductions are possible if LIFR CIGs persist. Moderate west to northwest winds continue with lighter and locally variable winds expected overnight. Minor changes to timing of stratus clearing tomorrow morning - moderate confidence that stratus will dissipate around 18-19Z with an early return expected tomorrow evening.

MARINE
(Tonight through next Tuesday)
Issued at 1056 PM PDT Wed Sep 11 2024

Winds gradually decreasing overnight, but remaining breezy. Winds increase Thursday afternoon with Gale force gusts in the outer waters.

MTR WATCHES/WARNINGS/ADVISORIES
CA...None.
PZ...Small Craft Advisory until 3 AM PDT Thursday for Mry Bay-SF Bay N of Bay Bridge.

Small Craft Advisory until 3 AM PDT Friday for Pigeon Pt to Pt Pinos 10-60 NM-Pt Arena to Pt Reyes 0-10 nm-Pt Pinos to Pt Piedras Blancas 0-10 nm-Pt Reyes to Pigeon Pt 0-10 nm.

Small Craft Advisory until 3 PM PDT Thursday for Pigeon Pt to Pt Pinos 0-10 nm.

Small Craft Advisory until 9 AM PDT Thursday for Pt Arena to Pt Reyes 10-60 NM.

Gale Warning from 9 AM Thursday to 3 AM PDT Friday for Pt Arena to Pt Reyes 10-60 NM.