Monday, September24, 2018 L-36.com


Marine Weather and Tides
Half Moon Bay, CA

Version 3.4
What's New / NOTES
9/17/2018 XTide broke when 1and1 "upgraded" my server. It has been esculated. I am sorry for the problem.

Sunrise 6:58AMSunset 7:03PM Monday September 24, 2018 10:41 AM PDT (17:41 UTC) Moonrise 6:18PMMoonset 5:27AM Illumination 100% Phase: Full Moon; Moon at 15 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
PZZ545 Coastal Waters From Point Reyes To Pigeon Point California Out To 10 Nm- 857 Am Pdt Mon Sep 24 2018
Today..SW winds up to 10 kt. Wind waves 2 ft or less...becoming 3 ft this afternoon. NW swell 3 to 5 ft at 9 seconds.
Tonight..SW winds up to 10 kt. Wind waves 2 ft or less. NW swell 3 to 5 ft at 9 seconds.
Tue..SW winds around 5 kt. Wind waves 2 ft or less. NW swell 3 to 4 ft at 9 seconds.
Tue night..W winds up to 10 kt. Wind waves around 3 ft. NW swell 3 to 5 ft at 9 seconds.
Wed..NW winds 5 to 15 kt. Wind waves around 3 ft. NW swell 3 to 5 ft at 10 seconds.
Wed night..NW winds 5 to 15 kt. Wind waves around 3 ft. NW swell 3 to 4 ft at 10 seconds.
Thu..W winds up to 10 kt. Wind waves 2 ft or less. NW swell around 3 ft.
Fri..W winds up to 10 kt. Wind waves 2 ft or less. NW swell around 3 ft.
...san francisco bar/fourfathom bank forecast..... In the deep water channel...combined seas 3 to 4 ft with a dominant period of 9 seconds. Across the bar...combined seas 4 to 5 ft with a dominant period of 9 seconds. Maximum ebb current of 2.6 knots at 04:01 pm Monday and 2.3 knots at 04:19 am Tuesday.
PZZ500 857 Am Pdt Mon Sep 24 2018
Synopsis for the central california coast and bays including the Monterey bay..Greater farallones...and cordell bank national marine sanctuaries... Split wind flow with light winds along the coast and breezy northwest winds in the outer waters. Winds will continue to diminish through the day but will remain locally breeze in the outer waters north of point reyes tonight. Light mixed swell, with a predominate short period northwest swell.


7 Day Forecast for Marine Location Near Half Moon Bay, CA
   Hourly   EDIT   Help
location: 37.47, -122.48     debug


Area Discussion for - San Francisco/Monterey Bay Area, CA
      (on/off)   Help   NOTE: mouseover dotted underlined text for definition
Fxus66 kmtr 241528
afdmtr
area forecast discussion
national weather service san francisco bay area
828 am pdt Mon sep 24 2018

Synopsis Warm high pressure will last at least through
Wednesday and possibly into Thursday. Cooling trend starts Friday
into Saturday as an upper low approaches.

Discussion As of 08:28 am pdt Monday... As noted on the
previous forecast discussion, the biggest weather impact to the
region today and Tuesday will be critical fire weather conditions
due to low humidity and increasing winds. Observations across
higher terrain this morning shows many locations in the single
digit relative humidity. Fortunately, winds are not overly strong
this morning, but still seeing some higher gusts. For what it's
worth the koak balloon sounding measured 3% at 850mb further
emphasizing the dry air mass. Red flag warnings remain in effect
through Tuesday 5 pm.

Completely on the flip side, morning visible satellite shows
widespread low clouds along the coast and locally inland,
especially monterey bay region. Ft ord profiler puts the marine
layer depth near 1k feet. Both monterey and salinas airports are
reporting vsby of 1 4 to 1 2 mile due to fog. We've also received
some reports of a chilly start to the day with lows in the mid to
upper 30s.

Lastly, the other weather impact for the week will be warmer
temperatures Tuesday and Wednesday. Inland valleys will warm well
into the 90s, which is several degrees above normal for late
september.

Prev discussion As of 3:44 am pdt Monday... Red flag warning has
been posted for the north and east bay hills. Getting numerous
reports of rh values in the single digits and even below 5%.

Luckily winds remain fairly light but when rh values are this dry
it doesnt take much wind to get us into red flag territory.

Outside of our area but a new fire started overnight up in butte
county as the initial shot of north winds works their way down the
state and into the bay area. To be clear the conditions this
morning are mainly focused on the very low humidity. Tonight the
gradients tighten and we do expect a stronger burst of moderate
north to northeast winds in the hills. This will occur with more
widespread drying with the NAM model showing some 20 kt wind barbs
during the pre-dawn hours of Tuesday morning. This is not a
strong wind event. However the other factors such as fuel dryness,
low humidity and quite frankly climatology warrant the red flags.

In addition we match up with the other red flags across the
state.

In terms of the public forecast, this just all means sunny and
seasonably warm late sept weather for the bay area. Expecting
widespread readings in the 80s today and even some 90s well inland
and in favored downslope regions. Marching forward if anything
expect continued warming trend Tuesday and weds with warm days,
mild nights, offshore winds and little or no marine influence.

Most populated areas will see mild overnight lows with night time
radiative inversions setting up that will allow for night time
cooling.

A cut-off low will approach by late Thursday or Friday and at the
very least induce a noted cooling trend. MOS guidance and model
output has been oscillating on potential shower chances over the
north bay as this feature moves through. Believe its prudent at
this point to lean towards climatology. 00z ECMWF backed off big
time on precip into the bay area. 06z GFS is offering some even
more far-fetched scenarios with the secondary trough bringing rain
to norcal while the remnants of tropical systems steer towards
baja. Point been is there is very low confidence in the long range
details at this time. Latest euro builds another strong ridge by
early october so if the troughs stay dry and to our northeast the
dry spell will continue.

Aviation As of 4:40 am pdt Monday... Stratus is limited to the
coastal areas south of point reyes due to light offshore flow.

Moisture at the surface is contributing to low vsbys within the
clouds. Patchy fog is also possible in sts.

Vicinity of ksfo...VFR.

Sfo bridge approach...VFR.

Monterey bay terminals... Lifr for low CIGS and vsbys blo 1 mile
through 16z.

Marine As of 04:35 am pdt Monday... High pressure off the
california coast is building into the pacific northwest creating a
light offshore flow over the coastal waters. This will result in
decreasing winds that will last through most of the week.

Mtr watches warnings advisories
Tday Sca... Pigeon pt to pt piedras blancas 10-60 nm until 9 am
sca... Pt arena to pigeon pt 10-60 nm until 3 pm
public forecast: mm rww
aviation: W pi
marine: W pi
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 14 mi42 min 61°F 69°F1012.3 hPa (+0.7)
FTPC1 - 9414290 - San Francisco, CA 23 mi42 min 55°F 61°F1012.1 hPa (+0.8)
PXOC1 - 9414311 - San Francisco (Pier 1), CA 23 mi42 min 58°F 1010.8 hPa (+0.8)
PXSC1 23 mi42 min 58°F 56°F
AAMC1 - 9414750 - Alameda, CA 23 mi42 min 60°F 65°F1012.1 hPa (+0.9)
46237 - San Francisco Bar, CA (142) 23 mi42 min 58°F4 ft
OMHC1 - 9414769 - Oakland Middle Harbor Met, CA 24 mi72 min WSW 2.9 G 2.9
OBXC1 24 mi42 min 58°F 57°F
OKXC1 - 9414776 - Oakland (Berth 34), CA 25 mi42 min 59°F 1011.8 hPa (+0.8)
LNDC1 25 mi42 min 60°F 1011.8 hPa (+0.8)
46026 - SAN FRANCISCO - 18NM West of San Francisco, CA 27 mi32 min SE 7.8 G 12 52°F 55°F1012.5 hPa
TIBC1 - Tiburon Pier, San Francisco Bay, CA 29 mi49 min SSE 6 60°F 1012 hPa (+1.0)
PPXC1 - 9414847 - Richmond (Point Potrero), CA 31 mi42 min 59°F 1012.2 hPa (+0.9)
RCMC1 - 9414863 - Richmond, CA 32 mi42 min 59°F 63°F1011.7 hPa
DPXC1 - 9415141 - Davis Point, San Pablo Bay, CA 42 mi42 min 61°F 1011.4 hPa (+0.6)
MZXC1 - 9415102 - Martinez-Amorco CA 43 mi42 min 63°F 67°F1011.4 hPa60°F
PRYC1 - 9415020 - Point Reyes, CA 45 mi42 min 55°F1011.8 hPa (+1.1)
PCOC1 - 9415144 - Port Chicago, CA 47 mi42 min 67°F 66°F1011.2 hPa (+0.5)
46042 - MONTEREY - 27NM West of Monterey Bay, CA 48 mi52 min NNW 1.9 G 3.9 55°F 57°F7 ft1011.7 hPa (+1.0)

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
N5
N7
NW8
NW14
N10
G13
NW11
G14
NW11
NW9
N10
N5
NW7
N4
NW3
NW1
NW3
SW1
SW2
W1
W3
S2
SE1
S2
SE2
NE3
1 day
ago
N4
N7
N7
G10
N10
G13
NW9
N9
NW11
NW9
G13
NW7
NW5
G8
NW4
E1
S2
SW1
NW4
NW3
W2
W2
S2
SW2
W2
W1
--
NE1
2 days
ago
N6
NW7
NW11
G14
NW13
G16
N14
G17
N12
G16
NW12
G15
N14
N10
N9
N6
NW4
NW2
N3
NW4
NW4
NW4
W5
W3
W3
E2
S1
W2
NW2

Airport Reports
    EDIT      (on/off)   Help   Click EDIT to display multiple airports
AirportDistAgeWind ktVisibilitySky/WeatherTempDewPtHumidityPressure
Half Moon Bay Airport, CA3 mi47 minSSE 10 G 144.00 miFog/Mist50°F50°F100%1012.5 hPa
San Francisco, San Francisco International Airport, CA12 mi46 minENE 510.00 miFair62°F54°F75%1011.5 hPa
San Carlos Airport, CA13 mi55 minVar 38.00 miA Few Clouds with Haze63°F55°F77%1011.8 hPa
Palo Alto Airport, CA19 mi55 minNE 510.00 miA Few Clouds63°F0°F%1012.2 hPa
Oakland, Metro Oakland International Airport, CA21 mi49 minS 47.00 miA Few Clouds60°F55°F84%1012.1 hPa
Mountain View, Moffett Field, CA23 mi1.8 hrsN 09.00 miFair60°F54°F80%1012.2 hPa
Hayward, Hayward Air Terminal, CA23 mi48 minN 09.00 miFair63°F53°F70%1012.6 hPa

Wind History from SFO (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 24hrNW11NW14NW14NW16NW14W13NW15W15NW11NW11W10W10NW8W7W7W6W6W8W5CalmW4CalmCalmE5
1 day agoNW6NW9NW14NW11W17NW18NW16W17NW14NW15NW10W11W6W7NW8NW7W5W4W4W8W6W6NW8NW8
2 days agoN4N8N8NW11NW15NW14NW16NW18NW16W14W16W10W5W7W11W10W11W8W6S3CalmCalm3NW4

Tide / Current Tables for Half Moon Bay, California
   EDIT   RT Ports Option   Weekend mode (on/off)   (on/off)   Help   One Week of Data
Tide / Current data from XTide NOT FOR NAVIGATION
Sorry tide depth graphs only, please select another station.


Tide / Current Tables for San Mateo Bridge, South San Francisco Bay, California Current
   EDIT      (on/off)   Help   One Week of Data
Tide / Current data from XTide NOT FOR NAVIGATION
Sorry tide depth graphs only, please select another station.


Weather Map and Satellite Images
       (on/off)   HelpWeather Map
wmap_P
GOES 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 (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.