Thursday, January23, 2020
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Marine Weather and Tides
Portola Valley, CA

Version 3.4
NOTICE
12/16/2019 NOAA is having trouble with requests that include wind gusts. I am posting graphs without wind gusts until it gets fixed.
10/9/2019 Updated the Marine Zones.
9/4/2019 Fixed the weather maps due to NOAA moving them.
7/25/2019 New feature in the Airports section gives a link to 5 minute updates for data reports.

Sunrise 7:16AMSunset 5:23PM Thursday January 23, 2020 3:22 AM PST (11:22 UTC) Moonrise 6:34AMMoonset 4:23PM Illumination 3% Phase: Waning Crescent; Moon at 28 days in cycle
NOTE: Some of the data on this page has not been verified and should be used with that in mind. It may and occasionally will, be wrong. The tide reports are by xtide and are NOT FOR NAVIGATION.
Marine Forecasts
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PZZ531 San Francisco Bay South Of The Bay Bridge- 237 Am Pst Thu Jan 23 2020
Today..NW winds up to 10 kt.
Tonight..NW winds around 5 kt.
Fri..NW winds up to 10 kt. Patchy fog.
Fri night..NW winds up to 10 kt.
Sat..N winds around 5 kt. Patchy fog. A slight chance of rain.
Sat night..SE winds around 5 kt. Rain likely.
Sun..W winds up to 10 kt.
Mon..W winds up to 10 kt.
PZZ500 237 Am Pst Thu Jan 23 2020
Synopsis for the central california coast and bays including the Monterey bay..Greater farallones...and cordell bank national marine sanctuaries... Light winds and diminishing seas through the day. Winds will generally be offshore and locally breezy near coastal gaps during the afternoon. A long period wnw swell will begin to move into the waters later today, peaking on Friday and Saturday. A coastal jet with northerly winds will develop along the big sur coast by Friday afternoon, generating small craft advisory winds there. The next storm approaches later Saturday into Sunday with increasing southerly winds followed by another large northwest swell behind the front Sunday into Monday.


7 Day Forecast for Marine Location Near Portola Valley, CA
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location: 37.36, -122.23     debug


Area Discussion for - San Francisco/Monterey Bay Area, CA
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FXUS66 KMTR 230557 AFDMTR

Area Forecast Discussion National Weather Service San Francisco Bay Area 957 PM PST Wed Jan 22 2020

SYNOPSIS. Mainly dry weather conditions along with a gradual warming trend is expected through Friday. A weak storm system moving into Northern California will bring a chance of precipitation to the region this upcoming weekend.

DISCUSSION. as of 9:10 PM PST Wednesday . Temperatures finished off on average 3 to 6 degrees warmer across the board today with some locations in the warmer inland areas seeing upward of 11 degrees of warming. Temperatures reached mid 50s to mid 60s under the influence of a building trough despite patchy morning fog and a slow clearing this morning.

Mostly clear skies persist across the region at this hour with a few high clouds streaming across the sky. Lingering low level moisture and light winds will once again lead to patchy low clouds and fog overnight. Satellite imagery depicts low clouds already developing along the Big Sur coast as well as advecting into the eastern portions of Alameda, Santa Clara, and San Benito counties from the Central Valley.

From previous discussion . Mainly dry weather conditions will persist through late week with a gradual warming trend region- wide. Will likely see more widespread 60s during the afternoon hours by Thursday, Friday and potentially Saturday as high pressure builds over the region. Cannot even rule out a few of the warmer interior locations of the Central Coast approaching 70s deg F late this week. The only chance of precipitation late in the week will be over northern Sonoma County late Thursday into Friday when a system passes inland to the north. Regardless, widespread precipitation is not likely.

The next chance of widespread rainfall is forecast for this upcoming weekend when a mid/upper level trough pushes into the Pacific Northwest. This will drag a frontal boundary into the North Bay sometime around Friday night before moving southward through the weekend. While this system looks to bring some precipitation to much of the region, widespread heavy rainfall is unlikely. Additionally, impacts from this system will be minimal with mostly beneficial rainfall. Temperatures will also cool late in the weekend into early next week in response to the upper level trough. Precipitation chances diminish early next week for much of the region as weak ridging builds back into place. However, unsettled conditions are likely to persist over northern California through at least the first half of next week as systems push inland. This may allow for some light rainfall over the North Bay, but again widespread impacts are unlikely.

AVIATION. as of 09:55 PM PST Wednesday . For 06z TAFs. Skies are mostly clear with a few high clouds passing overhead this evening. Near surface moisture remains elevated and patchy low cloud and fog development will be a concern tonight through Thursday morning. Fog is most likely across the North Bay overnight. Have maintained mention of low clouds and reduced vis across the Bay Area terminals in the tafs but confidence remains low. High clouds will increase and thicken late tonight. Any fog which forms tonight will clear by Thursday afternoon, with VFR during the afternoon hours. Winds will generally be light through the period.

Vicinity of KSFO . VFR expected through 12z with passing high clouds. Low clouds and patchy fog may develop after 12z, however exact timing and coverage remain lower confidence. Patchy haze and reduced vis will be possible through 21z Thursday, otherwise VFR Thursday afternoon and evening. Winds will be light through the period. A weak boundary late in the period will bring increased low-level moisture and low clouds late Thursday night.

SFO Bridge Approach . Similar to KSFO.

Monterey Bay Terminals . Comms issues continue with Salinas ASOS and FAA lines. VFR expected late this evening with patchy low clouds and fog returning early Thursday morning. Exact timing and coverage remain lower confidence. Light offshore winds through Thursday morning with onshore winds Thursday afternoon.

MARINE. as of 8:57 PM PST Wednesday . Seas will continue to decrease overnight into Thursday with light winds over the waters. Generally light winds will persist Friday and Saturday with high pressure over the region. However a long period northwest swell will pass through the waters Friday and Saturday. The next storm approaches later Saturday into Sunday with increasing southerly winds followed by another large northwest swell behind the front Sunday into Monday.

MTR WATCHES/WARNINGS/ADVISORIES. Tngt. None.

PUBLIC FORECAST: CW AVIATION: ST MARINE: ST

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Weather Reporting Stations
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Stations Dist Age Wind Air TempWater Temp WavesPressureDewPt
RTYC1 - 9414523 - Redwood City, CA 10 mi53 min SW 1.9 G 2.9 49°F 53°F1024.9 hPa
AAMC1 - 9414750 - Alameda, CA 29 mi53 min 52°F
LNDC1 30 mi53 min Calm G 0 51°F 1024.4 hPa
PXOC1 - 9414311 - San Francisco (Pier 1), CA 31 mi53 min WNW 1.9 G 5.1 51°F 1023.5 hPa
OMHC1 - 9414769 - Oakland Middle Harbor Met, CA 31 mi53 min NW 7 G 8
OBXC1 31 mi53 min 52°F 52°F
PXSC1 32 mi53 min 53°F 51°F
OKXC1 - 9414776 - Oakland (Berth 34), CA 32 mi53 min N 6 G 7 51°F 1024.5 hPa
FTPC1 - 9414290 - San Francisco, CA 33 mi59 min N 9.9 G 11 53°F 53°F1024.5 hPa
46012 - HALF MOON BAY - 24NM South Southwest of San Francisco, CA 35 mi43 min N 7.8 G 9.7 54°F 54°F1024.1 hPa51°F
46237 - San Francisco Bar, CA (142) 36 mi53 min 53°F6 ft
PPXC1 - 9414847 - Richmond (Point Potrero), CA 38 mi53 min N 8.9 G 11 51°F 1024.8 hPa
TIBC1 - Tiburon Pier, San Francisco Bay, CA 39 mi54 min W 1.9 51°F 1025 hPa
RCMC1 - 9414863 - Richmond, CA 40 mi53 min 52°F
46042 - MONTEREY - 27NM West of Monterey Bay, CA 41 mi43 min NNW 3.9 G 5.8 54°F 55°F1023.6 hPa53°F
46026 - SAN FRANCISCO - 18NM West of San Francisco, CA 42 mi43 min E 9.7 G 14 55°F 54°F1024.5 hPa
46092 - MBM1 43 mi66 min ENE 9.7 55°F 55°F1022.8 hPa (-0.9)
46114 - West Monterey Bay, CA 44 mi53 min 55°F10 ft
ELXC1 - Elkhorn Slough Reserve, CA 46 mi98 min ESE 2.9 53°F 1022 hPa50°F
MZXC1 - 9415102 - Martinez-Amorco CA 47 mi53 min E 2.9 G 4.1 48°F 51°F1025.1 hPa
UPBC1 47 mi53 min ESE 5.1 G 7
DPXC1 - 9415141 - Davis Point, San Pablo Bay, CA 48 mi53 min E 6 G 6 50°F 1024.6 hPa
PCOC1 - 9415144 - Port Chicago, CA 49 mi53 min ENE 1.9 G 1.9 48°F 49°F1024.7 hPa

Wind History for Redwood City, CA
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Airport Reports
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AirportDistAgeWind ktVisibilitySky/WeatherTempDewPtHumidityPressure

Link to 5 minute data for KPAO

Wind History from PAO (wind in knots)
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Last 24hr------------------CalmCalmCalmCalmN5--N5N4N5N7NW4NW4W4W4Calm
1 day ago------------------E3SE8SE6SE11SE7--SE10S11SE10SE9SE10SE11--SE10SE7
2 days ago--------------------Calm3Calm--Calm43--CalmCalmCalmSE5CalmSE3

Tide / Current Tables for Palo Alto Yacht Harbor, California
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Palo Alto Yacht Harbor
Click for Map
Thu -- 12:15 AM PST     6.63 feet High Tide
Thu -- 05:53 AM PST     2.95 feet Low Tide
Thu -- 06:34 AM PST     Moonrise
Thu -- 07:18 AM PST     Sunrise
Thu -- 11:07 AM PST     9.09 feet High Tide
Thu -- 04:22 PM PST     Moonset
Thu -- 05:22 PM PST     Sunset
Thu -- 06:33 PM PST     -0.87 feet Low Tide
Tide / Current data from XTide NOT FOR NAVIGATION
Sorry tide depth graphs only, please select another station.

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6.66.56.15.34.23.333.65.16.98.49.18.77.664.12.10.4-0.7-0.80.32.14.15.7

Tide / Current Tables for Dumbarton Hwy Bridge, South San Francisco Bay, California Current
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Dumbarton Hwy Bridge
Click for Map
Thu -- 12:31 AM PST     -0.00 knots Slack
Thu -- 03:19 AM PST     -0.61 knots Max Ebb
Thu -- 05:52 AM PST     0.00 knots Slack
Thu -- 06:34 AM PST     Moonrise
Thu -- 07:18 AM PST     Sunrise
Thu -- 08:54 AM PST     1.38 knots Max Flood
Thu -- 11:30 AM PST     -0.01 knots Slack
Thu -- 03:19 PM PST     -1.49 knots Max Ebb
Thu -- 04:22 PM PST     Moonset
Thu -- 05:22 PM PST     Sunset
Thu -- 06:51 PM PST     0.00 knots Slack
Thu -- 10:12 PM PST     1.96 knots Max Flood
Tide / Current data from XTide NOT FOR NAVIGATION
Sorry tide depth graphs only, please select another station.

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0.5-0.2-0.5-0.6-0.6-0.40.10.81.21.41.10.5-0.3-0.8-1.3-1.5-1.4-1.1-0.60.11.11.721.8

Weather Map
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wmap_P
GEOS Local Image of CentralWestCoast    EDIT
NOTE: East coast views moved to GEOS-16. They are experimental and not well supported by NOAA so they may not be correct so be warned. This change required redoing a large amount of the GOES code. If the image you are expecting is not showing, please let me know. You may need to use the EDIT function to update your location.
Link to Loop

Other links: Northern Pacific     Contential US     Full GOES-East
Wind Forecast for San Francisco/Monterey Bay Area, CA (6,6,7,8)
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Ground Weather Radar Station San Francisco Bay Area, CA
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weather_mapweather_map weather_map

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The information on this web site has not been checked for accuracy. It is for entertainment purposes only and should be independently verified before using for any other reason. There are five sources. 1) Documents and manuals from a variety of sources. These have not been checked for accuracy and in many cases have not even been read by anyone associated with L-36.com. I have no idea of they are useful or accurate, I leave that to the reader. 2) Articles others have written and submitted. If you have questions on these, please contact the author. 3) Articles that represent my personal opinions. These are intended to promote thought and for entertainment. These are not intended to be fact, they are my opinions. 4) Small programs that generate result presented on a web page. Like any computer program, these may and in some cases do have errors. Almost all of these also make simplifying assumptions so they are not totally accurate even if there are no errors. Please verify all results. 5) Weather information is from numerous of sources and is presented automatically. It is not checked for accuracy either by anyone at L-36.com or by the source which is typically the US Government. See the NOAA web site for their disclaimer. Finally, tide and current data on this site is from 2007 and 2008 data bases, which may contain even older data. Changes in harbors due to building or dredging change tides and currents and for that reason many of the locations presented are no longer supported by newer data bases. For example, there is very little tidal current data in newer data bases so current data is likely wrong to some extent. This data is NOT FOR NAVIGATION. See the XTide disclaimer for details. In addition, tide and current are influenced by storms, river flow, and other factors beyond the ability of any predictive program.