Issued at 205 PM PDT Tue Jun 3 2025
Cloudy coastal mornings followed by breezy and clearing afternoons will the prevailing pattern over the next few days. Coastal areas look to peak into the 60s while more interior areas stick to the 80s. The overnights keep lows in the 50s. Expect a slight warming and drying trend over the weekend and into the next work week.
, Issued at 241 AM PDT Wed Jun 4 2025 (Today and tonight)
Key Messages -June Gloom with patchy coastal drizzle -Breezy to gusty onshore flow
Overnight satellite fog product is definitely giving some June Gloom vibes with a solid stratus deck covering: the coastal areas, into SF Bay, North Bay Valleys, and Salinas Valley. Decent inland penetration with a meager depth hovering around 1200-1500 feet. Patchy fog and patchy drizzle will be possible along the immediate coast this morning. In classic fashion the marine layer will slowly erode back to the coast by this afternoon. Given the prevailing NW flow and building onshore flow coastal areas will hold onto some clouds through out the day and not fully clear. As such, we'll see a pretty large spread with sensible weather along the coast to inland areas. AKA the land of mirco-climates. Coastal areas will remain cool and in the upper 50s to near 70, which is seasonably cool for early June. Farther inland, sunshine will allow for a decent warm up with temperatures maxing out in the 70s to lower 90s, which is at or seasonably mild for early June. Speaking of onshore flow, SFO-SAC gradient will increase through the day with some guidance suggesting 4 to 5 mb, which is pretty solid. There we'll see some stronger onshore winds this afternoon with breezy to gusty conditions along the coast, inland valleys,gaps,and passes. Gusts 30-40 mph in the windiest locations.
For tonight- the marine layer will return again with more coastal drizzle/fog possible. Given the onshore flow inland penetration appears to be decent again and will be similar to this morning.
..issued at 325 AM PDT Wed Jun 4 2025 (Thursday through Tuesday)
Key Messages -Temperature roller coaster with a gradual warm up -Marine layer remains with some coastal drizzle
Interesting longwave pattern continues to impact the West Coast with ridging heading into another cut-off low into the weekend. Current setup shows a broad upper trough extending down the Aleutians. Farther east is a robust area of high pressure off the West Coast extending into the PacNW. Rounding the eastern periphery of the high are embedded upper level vort max/shortwave troughs. So how does this pattern evolve for the long term? The upper ridge will nose farther into the PacNW/NorCal as passing vort maxes/shortwaves deepen/dig over SoCal Wednesday into Thursday. This will generally keep sensible weather on repeat: marine layer with coastal drizzle/fog and seasonably cool temperatures for Thursday. By Friday, one of the shortwaves deepens enough off CA to become cut-off from the mean flow leading to another meandering upper low. The placement of the low and nosing ridge will kick off a subdued warming trend Friday through Monday. Despite the warming trend the marine layer will not completely go away. Daytime temperatures will range from the upper 70s to upper 90s away from marine influence. Coastal/bays will be in the upper 50s to lower 70s. Not much of a HeatRisk concern during this timeframe. Given the pesky upper low meandering off the coast one always has to think convection potential. While some of the global models shows some spokes of upper level moisture passing overhead thunderstorm potential at this time seems to be confined to the Sierra crest region.
Early next week the upper low finally moves inland and this will bring a subtle cool down across the region.
Definitely some nuances during the long term, but all in all rather quiet weather for our region.
(12z TAFS) Issued at 427 AM PDT Wed Jun 4 2025
The marine layer is around 1,500 feet deep with IFR ceilings reaching most of the terminals this morning. For the coastal sites, June gloom will be in full effect today as the stratus only breaks for a few hours in the afternoon before returning early this evening. Visibility restrictions will also be possible, with more widespread and longer duration impacts expected tomorrow morning as slightly cooler air brings higher relative humidity to the boundary layer. Despite the complexities, the GFSLAMP has maintained a good handle on the situation overnight and the author of the 12Z TAFs relied heavily on its guidance.
Vicinity of SFO, SFO is in one of the only patches of clear sky, and it's unclear exactly how long these conditions will last. The best chance for IFR-MVFR ceilings is between 13Z and 16Z, and the TAF hints at this with a tempo line as the conditions may be transient. Otherwise clearing is expected this afternoon with moderate onshore wind. There is higher confidence in a long duration stratus deck tomorrow morning.
SFO Bridge Approach, The stratus hole is starting to close in the South Bay and the approach will have a higher chance of impacts compared to the terminal through the morning hours.
Monterey Bay Terminals, A robust stratus intrusion is impacting the Central Coast terminals, and these conditions will persist through the majority of the day. We are only expecting around 6 hours of clearing this afternoon before an early return of stratus this evening.
(today through Monday) Issued at 427 AM PDT Wed Jun 4 2025
The gradient between subtropical high pressure over the Eastern Pacific and a trough over the coast of California is supporting gale force winds in the far NW coastal waters, with very rough seas. These winds will gradually diminish over the next 48 hours, with more favorable conditions expected through the remainder of the week. A southerly coastal jet will bring strong onshore winds tonight in the San Francisco Bay and in the exposed waters across the Golden Gate.
Ca, None. PZ, Small Craft Advisory from 9 PM this evening to 3 PM PDT Thursday for Pt Reyes to Pigeon Pt 0-10 nm-SF Bay N of Bay Bridge.
Gale Warning until 3 AM PDT Thursday for Pt Arena to Pt Reyes 10- 60 NM.
