SHORT TERM
(Today and tonight)
Issued at 330 AM PDT Sat Jul 27 2024

Widespread seasonal to below average temperatures continue.
Temperatures will drop between 5 to 10 degrees across the interior today compared to yesterday as upper level troughing strengthens over the Western US. High temperatures across the interior are expected to be in the 70s to low 80s while highs closer to the coast will be in the 60s to low 70s. Interior Monterey and San Benito counties continue to be the hottest portions of our CWA with highs in the mid 80s to low 90s expected today. The marine layer remains fairly deep between 2000-2500 feet with satellite currently observing widespread stratus over much of the Bay Area and Central Coast. Ensemble guidance indicates moderate to high confidence in today's high temperature forecast but some uncertainty remains depending on how fast stratus dissipates this morning. If stratus dissipates more slowly than currently forecast, it may result in areas where stratus persisted for a longer time period struggling to reach their forecasted highs.

The HRRR and NBM both indicate that light drizzle is possible this morning and again tonight for locations directly along the coast and in areas where upslope ascent is favored. The most recent ECMWF runs show fairly dry low level conditions at 850mb and 700mb. As such, measurable precipitation beyond a trace to a few hundredths of an inch is not expected. The NBM continues to indicate some potential (20-40%) of scattered light showers over the marine environment overnight.

LONG TERM
(Sunday through Friday)
Issued at 330 AM PDT Sat Jul 27 2024

Seasonal to below average temperatures will continue through mid- week before trending seasonal to slightly above average by late next week. Upper level troughing will deepen Saturday into Sunday before the upper level low pressure system moves to the northeast and away from the West Coast by late Sunday. The upper level flow will then become more zonal (horizontal) by Monday, allowing for slight warming to occur with temperatures expected to increase by a few degrees each day from this point on. By mid-week, upper level ridging will again start to build over the West Coast with ridging and slightly above average temperatures to persist through the end of the forecast period. High temperatures will generally remain in the 70s to mid 80s on Sunday and Monday. Widespread highs in the low to mid 80s are expected to return inland (reaching into the upper 80s to low 90s across favored hot spots) Tuesday and Wednesday. By Thursday and Friday, high temperatures will reach the mid 80s to low 90s across the interior. For areas closer to the coast temperatures will not vary quite as much with temperatures primarily staying in the 60s directly along the coast and upper 60s to 70s slightly inland from the coast.

Moderate uncertainty remains in the high temperature forecast from Thursday onwards. Cluster guidance shows uncertainty in both where the ridge will set up and how strong that ridge will be. Most of the ensemble clusters favor the ridge setting up farther east of us but at least one cluster centers the ridge more directly over the West Coast. The strength and positioning of the ridge will impact how much our high temperatures increase next week with both ECMWF and GFS ensemble guidance showing a higher range of forecast highs from Thursday onwards. CPC guidance continues to favor slightly above average temperatures from Thursday onwards across our area which increases forecast confidence that temperatures will be slightly above average for the first week of August.

AVIATION
(12Z TAFS)
Issued at 330 AM PDT Sat Jul 27 2024

Deep marine layer developed overnight promoting widespread marine stratus. MVFR/IFR cigs are expected to linger well into the morning before mixing out and pulling back to the coast, where clouds are expected throughout most of the day. Inland terminals such as the North Bay and inland South and East bays will likely clear to VFR through mid-to-late morning, while coastal and Bay Area terminals may hold MVFR cigs through the period. Onshore wind pattern and gusty gap flows persist today into this evening.

Vicinity of SFO...High confidence in MVFR/IFR cigs through this morning with little chance of clearing through the afternoon. There is about a 4-5 hour window beginning around 21Z where a slight chance of SCT exists, but all guidance suggests cigs lingering through the TAF period.

SFO Bridge Approach... Similar to SFO.

Monterey Bay Terminals...IFR cigs persist through the morning with low confidence in clearing around midday to early afternoon.
Otherwise, high confidence in MVFR/IFR cigs returning later this afternoon and persisting into Sunday morning with some patchy DZ overnight.

MARINE
(Today through Thursday)
Issued at 330 AM PDT Sat Jul 27 2024

Moderate to breezy Northwest winds linger through the weekend before diminishing by early next week. Expect some strong gusts in the northern outer waters as well as along the Big Sur Coast through this afternoon. Significant wave heights will continue to abate through the weekend.

MTR WATCHES/WARNINGS/ADVISORIES
CA...None.
PZ...Small Craft Advisory until 9 AM PDT this morning for SF Bay N of Bay Bridge.

Small Craft Advisory from 3 PM this afternoon to 9 PM PDT this evening for Pt Pinos to Pt Piedras Blancas 0-10 nm.

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