UPDATE
Issued at 912 AM PDT Fri Sep 20 2024

Stratus is just starting to break up across the region, with the interior East Bay and the Carmel Valley clearing out the most visibly on satellite imagery. Some coastal drizzle was observed earlier this morning, with accumulations ranging from a trace to a few hundredths of an inch. Progressive clearing of stratus is expected inland with the immediate coast and parts of Monterey Bay remaining socked in through the day. No updates to the forecast at this time.

DialH

SHORT TERM
(Today and tonight)
Issued at 350 AM PDT Fri Sep 20 2024

Low stratus clouds have filled in along the coastline and interior gaps and valleys overnight and will begin to erode by mid/late morning except along the immediate coastline, especially Monterey Bay, where the marine boundary layer is reestablished with light onshore flow throughout the day. Gradual but steady H50 height increases in the wake of the upper low moving inland over SOCAL this afternoon will lift temperatures up about 5 degrees over inland locations from yesterdays high temperatures. High pressure continues to build offshore tomorrow, driving temperatures warmer on Saturday to around normal values for this time of year.

LONG TERM
(Saturday through Thursday)
Issued at 350 AM PDT Fri Sep 20 2024

Temperatures will gradually warm through the weekend into the beginning of next week. The forecasted max temperatures have trended slightly cooler but moderate heat risk across many inland locations Monday and Tuesday may still lead to the need for a Heat Advisory for those two days. There is poor consensus for the evolution of the synoptic pattern west of the Rockies for the first half of next week, as a weak upper level low develops off the coast of SOCAL.
Nonetheless, temperatures moderate somewhat for the second half of next week from Monday and Tuesdays peak. We appear to remain dry through the extended forecast after some welcomed rainfall over southern Monterey County yesterday.

AVIATION
(18Z TAFS)
Issued at 1057 AM PDT Fri Sep 20 2024

Mix of IFR and MVFR CIGs expected to gradually clear by late morning. Stratus has started to recede from inland locations (LVK, SJC, SFO) with all sites across the Bay Area to clear by 19-20Z.
Across the Central Coast, a healthy feed of stratus from Monterey Bay may keep ceilings around longer with clearing tentatively anticipated to occur around 20Z. Stratus will return again tonight but is not expected to be quite as widespread. Confidence is low to moderate that stratus will reach LVK and SJC overnight with current thinking that clouds will be predominantly scattered and any lower ceilings that do form will only be temporary in nature. Elsewhere, stratus is expected to return slightly later tonight with most Bay Area sites seeing returns between 06-10Z. Light, locally variable winds continue through the remainder of the morning before more moderate generally west to northwest winds return during the afternoon.

Vicinity of SFO...VFR to persist through the afternoon/evening before MVFR CIGs return overnight. CIGs look to stay on the MVFR-IFR border but the NBM and GLAMP are in agreement that CIGs should stay MVFR. Stratus is expected to return later tonight around 10Z compared to around ~09Z yesterday. Light northwest winds are expected to strengthen by early this afternoon with moderate west to northwest winds persisting through the remainder of the day.

SFO Bridge Approach...Similar to SFO.

Monterey Bay Terminals...A healthy feed of stratus continues to move into SNS and MRY which is pushing back the timing of clearing.
Moderate confidence that stratus will clear around 20-21Z for at least a few hours this afternoon. The main uncertainty revolves around how long stratus will continue feeding in from the Monterey Bay and if a scenario similar to yesterday, where clearing did not really happen, will occur. Assuming stratus does clear, an early return around 00-01Z is expected at both MRY and SNS with MVFR-IFR CIGs persisting through the rest of the TAF period. Moderate northwest winds persist during the day before weakening overnight.



MARINE
(Today through Wednesday)
Issued at 912 AM PDT Fri Sep 20 2024

Moderate northwesterly winds continuing through Monday, then decrease to become gentle towards Tuesday. Seas will continue to build through the weekend, with wave heights up to 13 feet in the far northern outer waters as large, and shorter period northwesterly swell continues to move into the waters. Seas begin to abate Tuesday through the end of the forecast period.

MTR WATCHES/WARNINGS/ADVISORIES
CA...None.
PZ...Small Craft Advisory until 9 PM PDT Saturday for Pt Arena to Pt Reyes 10-60 NM.