Saturday, December16, 2017 L-36.com


Marine Weather and Tides
Portola Valley, CA

Version 3.4
What's New / NOTES
6/25/2017 - NOAA is having a major issue that impact the 7 day forecast load times. Many users are reporting problems. The issue has been reported.
5/23/2017 - Worked with NOAA again to speed up the 7 day forecast load times. Thanks to them for being responsive.
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.

Sunrise 7:15AMSunset 4:53PM Saturday December 16, 2017 10:51 AM PST (18:51 UTC) Moonrise 5:42AMMoonset 4:11PM 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
    EDIT      (on/off)   Help
PZZ560 Coastal Waters From Pigeon Point To Point Pinos California Out To 10 Nm- 901 Am Pst Sat Dec 16 2017
.small craft advisory in effect through Sunday morning...
Today..NW winds 20 to 30 kt, increasing to 25 to 35 kt this afternoon. Wind waves 6 to 9 ft. W swell 8 to 10 ft at 14 seconds.
Tonight..N winds 20 to 30 kt with gusts up to 40 kt. Wind waves 5 to 8 ft. NW swell 9 to 11 ft at 14 seconds.
Sun..N winds 10 to 20 kt with gusts up to 25 kt. Wind waves around 3 ft. NW swell 9 to 10 ft at 13 seconds.
Sun night..N winds 5 to 15 kt. Wind waves 2 ft or less. NW swell 7 to 9 ft at 12 seconds.
Mon..E winds 5 to 10 kt. Wind waves 2 ft or less. NW swell 5 to 7 ft at 12 seconds.
Mon night..NE winds 5 to 10 kt. Wind waves 2 ft or less. NW swell around 5 ft at 11 seconds.
Tue..E winds up to 10 kt, becoming nw. Wind waves 2 ft or less. NW swell 4 to 7 ft.
Wed..NW winds up to 10 kt, becoming north. Wind waves 2 ft or less. NW swell 6 to 9 ft.
PZZ500 901 Am Pst Sat Dec 16 2017
Synopsis for the central california coast and bays including the Monterey bay..Greater farallones...and cordell bank national marine sanctuaries... Strong and gusty north winds will prevail in the post frontal environment through today and Sunday. The strong and gusty winds will create very steep wind waves and fresh swell, creating very rough and hazardous seas through the majority of the weekend.

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


Area Discussion for - San Francisco/Monterey Bay Area, CA
      (on/off)   Help   NOTE: mouseover dotted underlined text for definition
Fxus66 kmtr 161815
afdmtr
area forecast discussion
national weather service san francisco bay area
1015 am pst Sat dec 16 2017

Locally breezy conditions likely through Sunday morning...

Elevated fire danger particularly for higher elevation
locations for the same time...

Synopsis Dry weather will continue into next week. A mainly
dry cold front will sweep south over the area late Friday night
and early Saturday morning which then increases n-ne winds along
the ridges and peaks today.

Discussion As of 09:30 am pst Saturday... An elongated
vorticity lobe pushed inland from the coast overnight, passed over
our region early this morning, and is now moving eastwards beyond
the sierra nevada. In the wake of this disturbance, northerly
winds have drastically increased resulting in a wind advisory and
red flag warning for higher elevations as well as gale warnings
over the waters.

Earlier this morning, the strongest winds were confined to the
higher elevations and coastal waters due to the presence of a
nocturnal inversion decoupling the lower atmosphere from the
stronger winds aloft. These stronger winds aloft began to mix down
to the surface as the Sun rose and mixed out the nocturnal
inversion, with several spotters (from santa cruz, santa clara,
and napa county) calling in reports of the initial strong gusty
north winds between 7 and 9 am.

So far this morning, the strongest winds (42 mph sustained 61mph
peak gust) were (and currently are) at the los vaqueros raws at
1100 feet, located southeast of mount diablo and north of the
altamont pass. Elsewhere, gusts in excess of 45 mph has been
reported at many diverse locations, including: mt diablo, hawkeye
raws (ne of geyeserville), mt tamalpais, bodega bay, point reyes,
oakland hills, half moon bay, inland san benito county, through
the carquinez strait inland delta, portions of the big sur
mountains, and the coastal san mateo mountains.

Our main forecast challenge of the day will be to continue to
monitor the critical fire weather conditions both in terms of wind
and minimum relative humidity values. Please be mindful of the
environmental conditions today in you are planning any out door
activities that could result in unintended fire ignition. The
current forecast looks on track so no changes are planned until
the afternoon package is issued early this afternoon.

Previous discussion As of 3:00 am pst Saturday... Have been
keeping a close eye on surface observations during the midnight
shift as as a system crossed our region yesterday evening.

However, so far only a few locations have been gusting over 30 mph
with always windy mount diablo back under 40 mph. Models continue
to show stronger winds through the morning with greater pressure
gradients and continued caa. 850 mb values off the latest NAM have
a bullseye of nearly 60 kt over the north bay mountains close to
noon. 850 mb speeds for other spots show the potential for 40 to
50 mph. Not clear that we will see speeds that high based on how
current values compare to expected numbers, but feel that caution
remains the best course of action. Therefore, will keep the wind
advisory going into Sunday morning.

Other concern for higher elevations remains for fire weather with
relative humidity readings expected to quickly drop through the
day and barely recover tonight. Would expect spots above 1,000
feet to drop into the 10 to 20% range later today with many likely
to be under 30% for most of the night. Will keep the red flag
warning going.

Synoptically we will see a ridge of high pressure attempt to
rebuild into our region from the west, but that will quickly
flatten as a system approaches from the north. Models have been
flipping between some moisture and no moisture depending on the
expected track. Models are trending farther to the east which
favors drier weather, so pops were decreased. Still looks like an
outside chance for light rainfall mainly over the north bay
Tuesday night. Any amounts will be very light -- less than a tenth
of an inch.

After that a cool, dry, northerly flow will take shape as the
ridge becomes extremely amplified off the coast. That should lock
into place at least through christmas day. For those with travel
plans the end of next week, driving conditions should be ideal.

Aviation As of 10:15 am pst Saturday... 18z TAF package.VFR
conditions will dominate airports around the bay area monterey bay
regions. The main story will be gusty northerly winds. Local
observations have already shown increasing winds around the area,
such as gusts to 61 mph east of livermore. As daytime warming
occurs vertical mixing should become more effective, which will
help to bring some of the higher level winds to the surface. As
such, strong gusty conditions remain in the tafs today. The
strongest winds will remain just off the surface, so wind shear
remains or was introduced for all TAF sites. Winds will begin to
ease late afternoon and early evening from north to south.

Confidence in timing is high and moderate to high for wind speeds.

If anything, winds could be a little stronger than forecast.

Vicinity of ksfo...VFR. Northerly winds will continue to increase
today in the wake of a dry cold front. Sustained winds in the 15
to 25 kt range with gusts to 35 kt are expected.

Sfo bridge approach... Similar to ksfo.

Monterey bay terminals...VFR. Northerly winds will increase midday
into afternoon today. Sustained winds in the 10 to 15 kt range
with gusts around 20 kt expected.

Fire weather As of 3:15 am pst Saturday... A red flag warning
remains in effect through 10 am Sunday. Offshore flow is forecast
to strengthen through the day. Latest models continue to show rh
values dropping through day and poor recoveries Saturday night.

It's fairly common to have lower rh on night number two behind a
front with developing offshore flow. May not technically hit rh
criteria the first part of today, but decided to keep fire
weather concerns going given gusty winds, lack of recent rain,
very low rh (single digits) the last few nights and near record
values of ercs for the N bay mts and santa cruz diablo psas. Areas
of greatest concern will be above 1000 feet. Winds may be a tad
weaker on Saturday night, but rh recoveries worse. For what it's
worth, fire weather concerns are not that unusual for this time of
year. December 16, 2013, a wildfire broke out in big sur called
the pfeiffer fire.

Marine As of 08:52 am pst Saturday... Strong and gusty north
winds will prevail in the post frontal environment through today
and Sunday. The strong and gusty winds will create very steep
wind waves and fresh swell, creating very rough and hazardous
seas through the majority of the weekend.

Mtr watches warnings advisories
Tday Wind advisory...

sca... Pigeon pt to pt pinos 0-10 nm
glw... Pt arena to pigeon pt 10-60 nm
glw... Pt pinos to pt piedras blancas 0-10 nm
glw... Pigeon pt to pt piedras blancas 10-60 nm
sca... Pt arena to pt reyes 0-10 nm
sca... Sf bay
sca... Mry bay
sca... Pt reyes to pigeon pt 0-10 nm
public forecast: drp bell
aviation: bfg
marine: cw bfg
visit us at

Weather Reporting Stations
   EDIT       (on/off)   Help   NOTE: Click on distance to see the station location on a map
Stations Dist Age Wind Air TempWater Temp WavesPressureDewPt
RTYC1 - 9414523 - Redwood City, CA 10 mi52 min NNW 19 G 24 58°F 53°F1015.3 hPa
AAMC1 - 9414750 - Alameda, CA 29 mi52 min N 17 G 26 59°F 53°F1014.9 hPa (+0.5)
LNDC1 30 mi88 min NNW 11 G 19 58°F 1015.1 hPa
PXOC1 - 9414311 - San Francisco (Pier 1), CA 31 mi52 min NNW 24 G 31 58°F 1013.9 hPa
OMHC1 - 9414769 - Oakland Middle Harbor Met, CA 31 mi52 min N 18 G 22
OBXC1 31 mi52 min 59°F 29°F
PXSC1 32 mi52 min 60°F 25°F
OKXC1 - 9414776 - Oakland (Berth 34), CA 32 mi52 min N 19 G 23 58°F 1015.2 hPa (+1.0)
FTPC1 - 9414290 - San Francisco, CA 33 mi52 min N 25 G 32 59°F 54°F1014.6 hPa (-0.4)
46012 - HALF MOON BAY - 24NM South Southwest of San Francisco, CA 35 mi62 min NNW 25 G 31 56°F 57°F14 ft1014.4 hPa (+0.0)
46237 - San Francisco Bar, CA (142) 36 mi82 min 54°F8 ft
PPXC1 - 9414847 - Richmond (Point Potrero), CA 38 mi52 min N 22 G 35 61°F 1014.8 hPa (+0.4)
TIBC1 - Tiburon Pier, San Francisco Bay, CA 39 mi43 min NNW 24 59°F 1015 hPa
RCMC1 - 9414863 - Richmond, CA 40 mi52 min N 18 G 27 60°F 54°F1014.8 hPa (+0.4)
46042 - MONTEREY - 27NM West of Monterey Bay, CA 41 mi62 min N 21 G 27 57°F 58°F16 ft1013.6 hPa (+1.2)
46026 - SAN FRANCISCO - 18NM West of San Francisco, CA 42 mi62 min NW 23 G 27 54°F 54°F11 ft1015.5 hPa (+0.5)
46092 - MBM1 43 mi102 min NW 19 57°F 58°F1012.9 hPa (+0.5)
46114 - West Monterey Bay, CA 44 mi52 min 58°F15 ft
ELXC1 - Elkhorn Slough Reserve, CA 46 mi67 min NNW 5.1 57°F 1013 hPa40°F
MZXC1 - 9415102 - Martinez-Amorco CA 47 mi52 min N 21 G 28 60°F 53°F1015.3 hPa19°F
DPXC1 - 9415141 - Davis Point, San Pablo Bay, CA 48 mi52 min NNE 23 G 29 59°F 1015.1 hPa (+0.7)
PCOC1 - 9415144 - Port Chicago, CA 49 mi52 min NNW 18 G 21 57°F 52°F1015.1 hPa (+0.9)

Wind History for Redwood City, CA
(wind in knots)    EDIT      (on/off)   Help
11
AM
12
PM
1
PM
2
PM
3
PM
4
PM
5
PM
6
PM
7
PM
8
PM
9
PM
10
PM
11
PM
12
AM
1
AM
2
AM
3
AM
4
AM
5
AM
6
AM
7
AM
8
AM
9
AM
10
AM
Last
24hr
NE2
N2
N7
N3
N3
N3
NW4
--
S2
W2
E2
SW1
SW2
NE1
W2
W2
W4
NW8
W6
W8
NW6
NW9
NW17
NW19
G24
1 day
ago
E3
G6
N4
NW6
NW7
NW3
W3
W3
SE1
SW2
SE1
W2
SW1
G4
SW2
SW2
W1
SE3
SW2
--
E1
S2
S2
--
--
E3
2 days
ago
NW5
SW1
N3
NW1
N2
NW2
E1
--
--
SW2
NW1
S3
S2
--
SW2
--
N1
SE2
--
SE2
N1
SW2
SE3
N1

Airport Reports
    EDIT      (on/off)   Help   Click EDIT to display multiple airports
AirportDistAgeWind ktVisibilitySky/WeatherTempDewPtHumidityPressure
Palo Alto Airport, CA10 mi65 minNW 2110.00 miClear and Breezy61°F33°F36%1014.9 hPa
Mountain View, Moffett Field, CA11 mi1.9 hrsNW 14 G 2210.00 miFair56°F36°F47%1015.1 hPa
San Carlos Airport, CA12 mi62 minNNW 11 G 1910.00 miA Few Clouds59°F26°F29%1015.2 hPa
San Jose, San Jose International Airport, CA16 mi59 minW 13 G 2110.00 miA Few Clouds59°F30°F33%1014.6 hPa
Half Moon Bay Airport, CA18 mi57 minN 15 G 229.00 miFair59°F32°F36%1013.5 hPa
San Francisco, San Francisco International Airport, CA19 mi1.9 hrsNNW 16 G 2510.00 miA Few Clouds59°F26°F28%1015.2 hPa
San Jose / Reid / Hillv, CA22 mi62 minNNW 1010.00 miClear57°F28°F33%1013.9 hPa
Hayward, Hayward Air Terminal, CA22 mi58 minNNW 1110.00 miFair60°F21°F22%1015.9 hPa
Oakland, Metro Oakland International Airport, CA23 mi59 minNNW 15 G 2410.00 miA Few Clouds59°F26°F28%1015 hPa

Wind History from PAO (wind in knots)
11
AM
12
PM
1
PM
2
PM
3
PM
4
PM
5
PM
6
PM
7
PM
8
PM
9
PM
10
PM
11
PM
12
AM
1
AM
2
AM
3
AM
4
AM
5
AM
6
AM
7
AM
8
AM
9
AM
10
AM
Last 24hr44--NW7N5N5NW6NW6CalmCalmCalm--------------------NW10NW15NW21
1 day ago84N8--W8NW6NW6NW6CalmCalmCalm------------------CalmCalm----
2 days ago--NW944N9NW5NW5--W5CalmCalm------------------CalmCalmCalmCalm

Tide / Current Tables for Granite Rock, Redwood Creek, San Francisco Bay, California
   EDIT   RT Ports Option   Weekend mode (on/off)   (on/off)   Help   One Week of Data
Granite Rock
Click for Map
Sat -- 05:06 AM PST     2.57 feet Low Tide
Sat -- 05:41 AM PST     Moonrise
Sat -- 07:17 AM PST     Sunrise
Sat -- 10:44 AM PST     8.80 feet High Tide
Sat -- 04:11 PM PST     Moonset
Sat -- 04:52 PM PST     Sunset
Sat -- 06:05 PM PST     -0.40 feet Low Tide
Tide / Current data from XTide NOT FOR NAVIGATION
Sorry tide depth graphs only, please select another station.
12am1am2am3am4am5am6am7am8am9am10am11am12pm1pm2pm3pm4pm5pm6pm7pm8pm9pm10pm11pm
6.66.15.13.932.62.94.15.77.38.58.88.26.9531.20-0.4-012.54.25.6

Tide / Current Tables for Dumbarton Hwy Bridge, South San Francisco Bay, California Current
   EDIT      (on/off)   Help   One Week of Data
Dumbarton Hwy Bridge
Click for Map
Sat -- 12:07 AM PST     -0.00 knots Slack
Sat -- 02:57 AM PST     -0.65 knots Max Ebb
Sat -- 05:41 AM PST     Moonrise
Sat -- 05:45 AM PST     0.01 knots Slack
Sat -- 07:16 AM PST     Sunrise
Sat -- 08:45 AM PST     1.33 knots Max Flood
Sat -- 11:24 AM PST     -0.01 knots Slack
Sat -- 03:03 PM PST     -1.33 knots Max Ebb
Sat -- 04:10 PM PST     Moonset
Sat -- 04:51 PM PST     Sunset
Sat -- 06:36 PM PST     0.00 knots Slack
Sat -- 09:55 PM PST     1.75 knots Max Flood
Tide / Current data from XTide NOT FOR NAVIGATION
Sorry tide depth graphs only, please select another station.
12am1am2am3am4am5am6am7am8am9am10am11am12pm1pm2pm3pm4pm5pm6pm7pm8pm9pm10pm11pm
0.1-0.4-0.6-0.6-0.6-0.30.20.81.21.310.4-0.3-0.8-1.2-1.3-1.2-0.9-0.40.41.21.61.81.5

Weather Map and Satellite Images
       (on/off)   Help
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 (13,3,4,5)
      (on/off)   Help

Ground Weather Radar Station San Francisco Bay Area, CA
   (on/off)   Help
weather_mapweather_map weather_map

Ad by Google

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.