Thursday, March30, 2017 L-36.com


Marine Weather and Tides
Portola Valley, CA

Version 3.4
What's New / NOTES
5/19/2016 - There were issues with the 3 day airport observation history. I switched to another data source. Let me know if you see any issues with the data feeds.
3/12/2015 - Added section for Gulf current for users in the GMZ marine zones.
This was requested by a user. If you have requests, please let me know.

Sunrise 6:54AMSunset 7:30PM Wednesday March 29, 2017 11:37 PM PDT (06:37 UTC) Moonrise 7:15AMMoonset 8:35PM Illumination 8% Phase: Waxing Crescent; Moon at 3 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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PZZ560 Pigeon Point To Point Pinos To 10 Nm- 919 Pm Pdt Wed Mar 29 2017
.small craft advisory in effect through Thursday afternoon...
.gale warning in effect from Thursday afternoon through late Thursday night...
Rest of tonight..NW winds 10 to 20 kt. Wind waves 2 to 4 ft. NW swell 8 to 10 ft at 15 seconds. Slight chance of showers after midnight.
Thu..NW winds 15 to 25 kt. Wind waves 3 to 5 ft. NW swell 9 ft at 14 seconds. Slight chance of showers in the morning.
Thu night..NW winds 20 to 30 kt. Wind waves 5 to 7 ft. NW swell 7 to 9 ft at 13 seconds.
Fri..NW winds 15 to 25 kt. Wind waves 3 to 5 ft. NW swell 9 to 11 ft at 12 seconds.
Fri night..NW winds 15 to 25 kt. Wind waves 3 to 5 ft. NW swell 10 to 12 ft at 12 seconds.
Sat..NW winds 10 to 20 kt. Wind waves 2 to 4 ft. NW swell 8 to 10 ft.
Sun..NW winds 20 to 30 kt. Wind waves 3 to 5 ft. NW swell 12 to 15 ft.
Mon..NW winds 15 to 25 kt. Wind waves 3 to 5 ft. NW swell 12 to 15 ft.
PZZ500 919 Pm Pdt Wed Mar 29 2017
Synopsis for the central california coast and bays including the Monterey bay..Greater farallones...and cordell bank national marine sanctuaries... Gusty northwest winds will accompany a cold frontal passage later tonight through Thursday morning. Surface high pressure will build over far northern california Thursday into Friday resulting in gale force winds over the coastal waters beginning later Thursday and continuing into Friday. Northwest swell will level off while swell periods steadily decrease tonight through Thursday. Large very long period northwesterly swell will move into the coastal waters Saturday evening into Sunday.

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 300407
afdmtr
area forecast discussion
national weather service san francisco bay area
907 pm pdt Wed mar 29 2017

Synopsis Cooler and breezy conditions are forecast for
Thursday after a cold front sweeps through the region. This
system may produce isolated light showers from late tonight into
early Thursday morning, however most locations will not receive
measurable rainfall. Locally strong and gusty northwest winds are
likely from Thursday afternoon into Friday. A warming trend is
then expected for the upcoming weekend as high pressure rebuilds
over the region.

Discussion As of 9:05 pm pdt Wednesday... Evening satellite
imagery shows a cold front moving through northwest california.

Clouds have begun to increase over our area in advance of the cold
front - mostly high clouds but also patchy low clouds in coastal
areas. This cold front is expected to sweep southeast and through
our area late tonight and early Thursday morning. Models continue
to indicate that most precipitation with this system will fall to
our north and east. However, the 00z NAM continues to show widely
scattered light precipitation across our area starting around
midnight tonight and continuing until shortly after sunrise Friday
morning. Most other models also indicate at least a slight chance
of precipitation. In any event, where rain does fall, amounts are
expected to be very light. A cooler airmass will arrive behind
the incoming cold front and high temperatures on Thursday are
expected to be 5 to 10 degrees cooler than today.

The primary weather impact from this system will be locally strong
and gusty northerly winds in the post-frontal environment starting
tomorrow. Nw-se surface pressure gradients are expected to
quickly steepen on Thursday as high pressure builds off the
northern california coast and low pressure deepens over far
southern california and nevada. Initially, on Thursday, strongest
northwest winds will occur along the coast. Coastal winds are
expected to increase in the morning but not reach their peak
intensity until late Thursday afternoon and early Thursday
evening. Coastal winds will then subside by late Thursday
evening. But as winds decrease near the coast, north winds are
expected to increase in the hills and be locally strong and gusty
from late Thursday night through midday Friday. A wind advisory
has been issued for most coastal zones from noon through 8 pm
Thursday and for most mountain zones from midnight Thursday night
through midday Friday. Local wind gusts up to 45 mph are likely
near the coast late Thursday, and winds gusts up to 50 mph are
expected in the hills by late Thursday night. Winds will subside
gradually through Friday and Friday night, but locally breezy
conditions are expected to continue into Saturday morning, mainly
in the hills.

These northerly winds will bring a much drier airmass into our
region by Friday. The dry airmass will mean cool temperatures in
the valleys to start the day Friday, but also a quick warmup once
the Sun rises. An upper ridge will then build over california by
Saturday, allowing temperatures to warm several degrees by the
weekend. Our weekend is shaping up to be dry with seasonably warm
temperatures.

Temperatures will cool early next week another system drops in
from the northwest. The Monday system looks less likely to
produce any precipitation in our area, but will result in breezy
conditions once again by Monday afternoon.

From previous discussion... The longer range guidance continues to
show a return to wet weather conditions by late next week. The
models generally agree that a more potent weather system will drop
southward into northern california by Thursday or Friday of next
week with a moderate moisture tap. Both the GFS and ECMWF show
widespread rainfall across the region by next Friday. However,
being more than a week out, confidence remains low at this time
and changes to the forecast are likely.

Aviation As of 5:59 pm pdt Wednesday... Fragments of coastal
stratus /MVFR cigs/ are developing from sonoma county to san mateo
county. A more solid band of low clouds is advancing southeastward
across the northern coastal waters per visible imagery. 925 mb
level warming is cresting late this afternoon and early evening
which may initially help suppress incoming coastal stratus and fog
under compressed marine inversions. However, fairly rapid and
significant cooling follows later tonight and Thursday morning,
e.G. NAM output is consistent with forecasting upwards of 10
celsius cooling at 925 mb. Advertised surface cold front accelerates
southeastward across the bay area tonight and north central coast
early Thursday morning accompanied by pockets of light rain or
drizzle.

Vicinity of ksfo...VFR with westerly winds gusts to 25-30 knots.

Based on late afternoon visible imagery and area observations
decided to forecast onset of MVFR cig a little earlier, coordinated
with cwsu office. 00z TAF indicates tempo MVFR cig as early as
05z (not in taf, but cig development may be 1-2 hours earlier than
forecast based on low clouds rapidly advancing over the coastal
waters plus there's additional stratus development on the san mateo
coast at the moment). Drizzle or light rain forecast by 07z accompanied
by a period of ifr cig until greater cooling arrives later tonight/Monday
which should lift CIGS back to MVFR.VFR returns by 17z Thursday,
expect strong and gusty w-nw winds Thursday afternoon and evening.

Sfo bridge approach... Similar to ksfo.

Monterey bay terminals...VFR with westerly winds 10-15 knots this
evening. Stratus developing to the NW will likely focus on the
monterey peninsula this evening, moderate to high confidence ifr
cigs developing between 04z-07z ifr then prevailing with light
drizzle or rain developing late tonight into Thursday morning.

Marine As of 4:49 pm pdt Wednesday... High pressure off the
california coast will keep moderate northwest winds through this
evening. Winds will briefly decrease tonight as the high weakens
but will increase again Thursday through Friday as strong low
pressure develops over the intermountain region. Long period
swells will continue through this evening. A larger long-period
swell is expected to arrive Sunday night and Monday.

Mtr watches/warnings/advisories
Tngt Sca... Pt arena to pt reyes 0-10 nm
sca... Pt reyes to pigeon pt 0-10 nm
sca... Pigeon pt to pt pinos 0-10 nm
sca... Pt pinos to pt piedras blancas 0-10 nm
sca... Pt arena to pigeon pt 10-60 nm from 3 am
sca... Pigeon pt to pt piedras blancas 10-60 nm from 3 am
sca... Rough bar advisory for sf bar until 8 pm
sca... Mry bay until 3 am
public forecast: dykema/rgass
aviation: canepa
marine: W pi
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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 mi49 min NW 5.1 G 5.1 56°F 62°F1020.5 hPa
AAMC1 - 9414750 - Alameda, CA 29 mi49 min W 4.1 G 8.9 57°F 61°F1020.9 hPa
LNDC1 30 mi49 min SW 5.1 G 8 57°F 1020.4 hPa
OMHC1 - 9414769 - Oakland Middle Harbor Met, CA 31 mi49 min SW 4.1 G 8
OBXC1 31 mi49 min 57°F 53°F
PXSC1 32 mi49 min 57°F 53°F
OKXC1 - 9414776 - Oakland (Berth 34), CA 32 mi49 min SSW 1 G 2.9 57°F 1020.5 hPa
FTPC1 - 9414290 - San Francisco, CA 33 mi49 min WSW 6 G 13 55°F 57°F1020.6 hPa
46012 - HALF MOON BAY - 24NM South Southwest of San Francisco, CA 35 mi47 min WNW 16 G 18 55°F 56°F9 ft1021.2 hPa (+0.6)
46237 - San Francisco Bar, CA (142) 36 mi67 min 56°F8 ft
PPXC1 - 9414847 - Richmond (Point Potrero), CA 38 mi49 min S 8 G 9.9 58°F 1020.6 hPa
RCMC1 - 9414863 - Richmond, CA 40 mi49 min NW 2.9 G 4.1 58°F 59°F1020.2 hPa
46042 - MONTEREY - 27NM West of Monterey Bay, CA 41 mi47 min 18 G 21 56°F 56°F11 ft1021.1 hPa (+0.6)
46026 - SAN FRANCISCO - 18NM West of San Francisco, CA 42 mi47 min NW 16 G 19 54°F 53°F8 ft1020.9 hPa (-0.0)
46092 - MBM1 43 mi88 min W 18 55°F 55°F1019.8 hPa (+1.3)
46114 - West Monterey Bay, CA 44 mi37 min 56°F11 ft
UPBC1 47 mi49 min WSW 4.1 G 9.9
MZXC1 - 9415102 - Martinez-Amorco CA 47 mi49 min WSW 7 G 11 60°F 58°F1019.7 hPa48°F
DPXC1 - 9415141 - Davis Point, San Pablo Bay, CA 48 mi49 min WSW 7 G 8.9 59°F 1019.8 hPa
PCOC1 - 9415144 - Port Chicago, CA 49 mi49 min SW 9.9 G 14 59°F 58°F1019 hPa

Wind History for Redwood City, CA
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Airport Reports
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AirportDistAgeWind ktVisibilitySky/WeatherTempDewPtHumidityPressure
Palo Alto Airport, CA10 mi2.8 hrsNW 1010.00 miPartly Cloudy59°F50°F72%1020.7 hPa
Mountain View, Moffett Field, CA11 mi1.7 hrsNNE 510.00 miFair55°F48°F80%1021.4 hPa
San Carlos Airport, CA12 mi42 minWNW 710.00 miFair57°F48°F72%1021.3 hPa
San Jose, San Jose International Airport, CA16 mi44 minNNW 510.00 miA Few Clouds56°F50°F81%1021 hPa
Half Moon Bay Airport, CA18 mi42 minNNW 9 G 145.00 miFog/Mist55°F53°F94%1022 hPa
San Francisco, San Francisco International Airport, CA19 mi41 minW 1210.00 miPartly Cloudy56°F51°F84%1020.6 hPa
San Jose / Reid / Hillv, CA22 mi1.8 hrsNNW 810.00 miClear57°F50°F77%1021.7 hPa
Hayward, Hayward Air Terminal, CA22 mi43 minWNW 510.00 miA Few Clouds57°F50°F78%1021.9 hPa
Oakland, Metro Oakland International Airport, CA23 mi44 minW 119.00 miA Few Clouds57°F55°F93%1020.8 hPa

Wind History from PAO (wind in knots)
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Last 24hr------------------CalmCalm--5N5N8NW12N15NW12NW12N12NW15NW13NW10NW10
1 day ago------------------CalmCalm44N8N8NW10NW15--W15NW15NW12NW16NW10NW8
2 days ago------------------W7W8W10NW12NW12NW18NW16NW18
G22
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--W17W10

Tide / Current Tables for Granite Rock, Redwood Creek, San Francisco Bay, California
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Granite Rock
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Thu -- 02:36 AM PDT     8.69 feet High Tide
Thu -- 06:56 AM PDT     Sunrise
Thu -- 08:56 AM PDT     Moonrise
Thu -- 09:21 AM PDT     -0.28 feet Low Tide
Thu -- 03:31 PM PDT     7.33 feet High Tide
Thu -- 07:30 PM PDT     Sunset
Thu -- 09:26 PM PDT     1.32 feet Low Tide
Thu -- 10:44 PM PDT     Moonset
Tide / Current data from XTide NOT FOR NAVIGATION
Sorry tide depth graphs only, please select another station.
12am1am2am3am4am5am6am7am8am9am10am11am12pm1pm2pm3pm4pm5pm6pm7pm8pm9pm10pm11pm
5.57.38.58.67.86.24.22.10.5-0.2-01.12.84.66.27.27.26.55.13.52.11.41.52.6

Tide / Current Tables for Dumbarton Hwy Bridge, South San Francisco Bay, California Current
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Dumbarton Hwy Bridge
Click for Map
Thu -- 12:24 AM PDT     1.80 knots Max Flood
Thu -- 03:13 AM PDT     -0.00 knots Slack
Thu -- 06:46 AM PDT     -1.47 knots Max Ebb
Thu -- 06:56 AM PDT     Sunrise
Thu -- 08:55 AM PDT     Moonrise
Thu -- 09:52 AM PDT     0.01 knots Slack
Thu -- 01:03 PM PDT     1.98 knots Max Flood
Thu -- 04:13 PM PDT     -0.01 knots Slack
Thu -- 07:15 PM PDT     -1.07 knots Max Ebb
Thu -- 07:29 PM PDT     Sunset
Thu -- 10:00 PM PDT     0.00 knots Slack
Thu -- 10:44 PM PDT     Moonset
Tide / Current data from XTide NOT FOR NAVIGATION
Sorry tide depth graphs only, please select another station.
12am1am2am3am4am5am6am7am8am9am10am11am12pm1pm2pm3pm4pm5pm6pm7pm8pm9pm10pm11pm
1.81.71.10.2-0.4-1-1.4-1.5-1.1-0.50.111.721.71.10.2-0.4-0.8-1.1-0.9-0.5-00.7

Weather Map and Satellite Images
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Weather Map
wmap_P
IR Satellite Image from GEOS
west_satellite

GOES Local Image of CentralWestCoast    EDIT
Geos

Wind Forecast for San Francisco/Monterey Bay Area, CA (2,6,7,8)
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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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Disclaimer:
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 numerious 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.