Marine Weather Net

San Francisco Bay South of the Bay Bridge Marine Forecast


TODAY

W
WINDS
10 - 15
KNOTS

TONIGHT

NW
WINDS
10 - 15
KNOTS

MON

NW
WINDS
10 - 20
KNOTS

MON NIGHT

NW
WINDS
10 - 20
KNOTS

The Marine Weather Forecast In Detail:
PZZ531 Forecast Issued: 242 AM PST Sun Nov 27 2022

SMALL CRAFT ADVISORY IN EFFECT FROM MONDAY MORNING THROUGH MONDAY EVENING
Today...Nw Winds Around 5 Knots...Becoming W 10 To 15 Knots This Afternoon.
Tonight...Nw Winds 10 To 15 Knots.
Mon...Nw Winds 10 To 20 Knots With Gusts Up To 30 Knots.
Mon Night...Nw Winds 10 To 20 Knots With Gusts Up To 30 Knots.
Tue...N Winds Around 5 Knots.
Tue Night...E Winds 5 To 10 Knots.
Wed...S Winds 5 To 10 Knots. A Chance Of Rain.
Thu...S Winds 10 To 15 Knots. Rain.
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Area Forecast Discussion
National Weather Service San Francisco Bay Area
335am PST Sunday Nov 27 2022

Synopsis
Cool and quiet through mid week. Frost and freezing temperatures are possible for inland areas. An unsettled pattern develops thereafter with rain possible later this week and into next weekend.

As of 01:30am PST Sunday... Today And Tonight
Moisture channel imagery reveals dry mid to upper level conditions across our area with upstream moisture across the Pacific Northwest and far NorCal. This moisture is occurring in association with a shortwave impulse out ahead of deeper troughing over British Columbia. Nighttime Microphysics imagery showed a patch of low stratus and fog was occurring both down the Salinas Valley and along adjacent portions of Monterey Bay. Clear skies and cool temperatures prevailed elsewhere across the area early this morning. For today, look for the upstream trough to drop into the Great Basin and Northern Rockies as surface low pressure deepens over the Canadian Prairies. An associated cold front should reach far NorCal by this evening. Meanwhile shortwave ridging will prevail locally leading to dry conditions and quiet weather outside any morning or late night fog. Temperatures should remain on the cool side with highs generally in the 60s. Lows tonight will dip into the 40s for many areas, with 30s in the cooler inland valleys.

Monday through Wednesday:

Upper troughing will extend from southwest Canada through the Intermountain West early in the period with a deeper trough approaching the Pacific Northwest by Wednesday. Deterministic models and their ensembles maintain a drier and more inland trend with the leading trough suggesting a dry frontal passage is the most likely forecast outcome on Monday. High pressure should lead to quiet conditions for Tuesday into Wednesday, with additional cooling following the frontal passage. High temperatures should reach the mid 50s to around 60, with lows mostly in the upper 20s and 30s, with some lower 40s near the coast and bays. The typically colder North Bay Valleys have a medium to high potential (50-80 percent) of experiencing freezing temperatures, with similar potential noted over San Benito and southern Monterey Counties. It's also worth noting a low potential exists (30-35 percent) for reaching freezing within portions of the Santa Clara valley surrounding San Jose. Temperature trends will be monitored in the days going forward but this is a good reminder to both protect sensitive vegetation and to check in on those without adequate access to heating during this period of colder weather.

Thursday through Saturday:

A meridional flow pattern should evolve with mean troughing establishing across the eastern Pacific and West Coast. WPC Cluster Analysis ensemble members are in good agreement in this pattern, with deterministic models and their ensembles also in phase. This lends confidence in potential rainfall during this part of the forecast period. Our first chance (50-70 percent PoPs) should occur on Thursday into Friday as a shortwave trough approaches NorCal. Deterministic models are currently spinning up a decent surface low just offshore complete with a robust low-level jet and focused push of warm/moist advection. This should provide decent forcing for ascent when juxtaposed with large-scale lift via jet-level divergence and increasing differential cyclonic vorticity advection. Model ensemble members are in decent agreement with their means and suggest increased confidence in widespread wetting rainfall. The National Blend of Models even has 30 percent probabilities for daily amounts reaching 0.5 inches in the coastal ranges with 15 to 20 percent probabilities for this happening in the lower elevations. Even the 10th percentile amounts from a consensus of all available model guidance suggests a decent shot for wetting rainfall. So while we'll need to fine tune details it appears that things may be looking up in the rain department.

A secondary shortwave should traverse the mean trough next weekend, which may provide additional rain chances. However model variability remains regarding the strength and placement of the key features. So wet weather may continue into the weekend, but there is less certainty in the timing and coverage at this time. Otherwise of greater confidence is the continuance of below average temperatures during this period.

Marine
as of 02:42am PST Sunday...Strong northwest winds out over the northern outer waters with 10 to 12 foot waves around 13 seconds. These winds will increase Sunday afternoon and gradually expand southward over all the waters into Monday. A moderate period northwest swell at 12 to 14 seconds persists in the background and will continue into early next week while a new, long period northwest swell arrives Sunday night into Monday morning.

NOAA San Francisco Bay Area Office: Watches - Warnings - Advisories
Today:
Small Craft Advisory...Point Arena to Point Reyes 0-10nm
from 9 AM Small Craft Advisory...Point Arena to Pigeon Point 10-60nm
Small Craft Advisory...Pigeon Point to Piedras Blancas 10-60 nm from 3pm