Issued at 855 AM PDT Sun May 10 2026
A deeper marine layer than anticipated (around 1500 ft in the North Bay and 2000 ft in the Bay Area and Central Coast) early this morning has resulted in a further inland extent of stratus. Thus, have lowered temperatures as mentioned in the short term discussion below, generally 3-5 degrees F cooler. Still expecting low clouds to retreat to the coast between 10 AM and 2 PM which will give way to mostly sunny conditions across inland areas.
RGass
, Issued at 1215 AM PDT Sun May 10 2026 (Today through Monday)
Let's step back and take a look at the interesting longwave pattern over the CONUS - ridge of high pressure covers CA which is bookended by deep troughs on either side with one near the Great Lakes and the other near Gulf of AK. The pattern will hold in the near term, but will shift with a pattern change on the horizon, literally. So what does this set up mean for the Bay Area? A ridge of high pressure in May usually brings dry and mild conditions and Sunday is no exception. However, it's the details that matter. Overnight satellite imagery shows solid stratus along the coast working its way inland. The marine layer will likely top out 900-1200 feet this morning and will be the spoiler for Max T potential. Would not be surprised one bit if the marine layer was able to squeeze out some drizzle along the coast. Model guidance has struggled the last few days regarding Max T and the marine layer influence, simply put the forecast was too warm. As such, trended temperatures downward from the NBM over inland valleys or areas that have a pronounced marine layer influence this afternoon. Went colder by 3-5 degs, but worried it wasn't under cut enough. That being said, do expect the marine layer clouds to erode back to the coast by this afternoon with inland sunshine and coastal clouds. Regardless, if you have outdoor activities to celebrate Mother's Day it will be pleasant with inland highs in the 70s and 80s and cooler at the coast in the 60s - bring a jacket. Could also be a tad breezy this afternoon with the temp difference from the coast to interior. Sfc pressure gradients remain onshore again, but are forecast to be weaker than Saturday where they peaked at 4.2 mb.
Sunday night through Monday - the center of the upper ridge begins to shift toward the Desert SW while the upstream trough deepens and inches toward the West Coast. Despite the shift, Monday is still on track to be the warmest day of the forecast. 850 mb temps peak at 20-22C. Mixing those temps to the surface under ideal conditions would bring toasty temps. However, we still have some onshore flow and lingering marine layer. As such, max temps will be tempered near the coast and bays, 60s to lower 80s. Far interior locations will be in the 90s leading to some Moderate HeatRisk.
..issued at 1220 AM PDT Sun May 10 2026 (Monday night through next Saturday)
The change in the longwave pattern begins to unfold Monday night into Tuesday. The upper level ridge is being replaced by a robust and anomalously deep upper low for mid May. Temperatures begin to drop in response to lower 500 mb heights and cooler 850 mb temps, but still above normal.
By Wednesday near normal temperatures return thanks to the cut-off low over the region. Confidence fades on the details of the exact placement of the cut-off low, cluster analysis is split with some favoring more zonal flow and others farther south with a deeper low. Regardless of exact placement, it's clear that temps drop and at least some drizzle is likely. A few members even show light showers Wednesday afternoon/evening (tstorms to the N).
Zonal flow returns for the second half of the work week leading to rebounding temperatures and drier conditions.
(18z TAFS) Issued at 1059 AM PDT Sun May 10 2026
Stratus is receding across the region with most sites to see CIGs clearing between 18/19Z. The question is if we will see clearing at HAF and MRY where continuous stratus feeds may allow overcast conditions to persist through the majority of the TAF period. Breezy afternoon/evening winds are likely again with gusts peaking between 20-25 knots. Locally stronger gusts are possible at SFO but they should stay below 30 knots on the higher end. Winds ease overnight. Stratus has returned early the last few days but models have started shifting tonight's return to be later in the TAF period with the stratus footprint potentially not as widespread tonight compared to previous nights. This is reflected by the marine layer dropping from around 2000 ft to around 1000 ft. MVFR-IFR CIGs are expected tonight but, especially on the coast, we may see further lowering and decreases in visibility (LIFR) as the marine layer compresses.
Vicinity of SFO, IFR with stratus to clear/VFR by 19/20Z. Winds strengthen during the afternoon/evening with gusts to around 28 knots. Model guidance keeps gusts today well below 30 knots but confidence is low to moderate. The SFO-WMC gradient looks to peak around +6-7 mb today which would support decently gusty winds this afternoon and evening. The 28 knot gusts listed in the TAF are on the higher end but SFO has seen gusts to 30-31 knots over the last few days with a much weaker SFO-WMC gradient. There is enough reasonable confidence given persistence and the strengthening SFO- WMC gradient to suggest moderate to strong gusts will redevelop again this afternoon. The stratus forecast is a little lower confidence given the compressing marine layer. The most likely scenario is stratus returning after 06Z and lingering through 17/18Z tomorrow. LAMP guidance suggests some potential for stratus to return as early as 03Z.
SFO Bridge Approach. Similar to SFO.
Monterey Bay Terminals, MVFR-IFR with stratus coverage receding across the Salinas Valley. Similar to yesterday, stratus continues to feed in along the Monterey Bay shoreline (including MRY). MRY is expected to maintain overcast conditions through at least 22Z before potentially remaining clear through 02Z. CIGs return to SNS by late tonight but there is some potential for an early return (02-03Z) similar to MRY. Gusty onshore winds are likely again during the
(today through Friday) Issued at 855 AM PDT Sun May 10 2026
Moderate seas and a fresh to strong northwest breeze with occasional near gale force gusts will continue through tonight. Locally gusty conditions are likely across the San Pablo and San Francisco Bays where terrain promotes wind funneling. Winds gradually ease starting late tonight across the inner waters then across the outer waters tomorrow becoming a moderate northwest breeze. Winds increase and seas build mid to late week.
Ca, None. PZ, Small Craft Advisory from 3 PM this afternoon to 9 PM PDT this evening for Mry Bay.
Small Craft Advisory until 3 AM PDT Monday for Pt Arena to Pt Reyes 0-10 nm.
Small Craft Advisory until 9 PM PDT this evening for Pigeon Pt to Pt Pinos 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 Monday for Pt Arena to Pt Reyes 10-60 NM.
Small Craft Advisory until 9 AM PDT Monday for Pigeon Pt to Pt Pinos 10-60 NM.
