Thursday, April2, 2020
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Marine Weather and Tides
Half Moon Bay, 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 6:50AMSunset 7:34PM Thursday April 2, 2020 8:12 AM PDT (15:12 UTC) Moonrise 12:26PMMoonset 2:31AM Illumination 71% Phase: Waxing Gibbous; Moon at 9 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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PZZ545 Coastal Waters From Point Reyes To Pigeon Point California Out To 10 Nm- 252 Am Pdt Thu Apr 2 2020
.gale warning in effect until 3 am pdt early this morning...
.small craft advisory in effect through Friday evening...
Today..NW winds 10 to 20 kt with gusts up to 25 kt, increasing to 20 to 30 kt with gusts up to 35 kt this afternoon. Wind waves 7 to 8 ft. Mixed swell nw 3 to 4 ft at 11 seconds and sw around 2 ft at 17 seconds.
Tonight..NW winds 20 to 30 kt with gusts up to 35 kt. Wind waves 9 to 10 ft. Mixed swell nw around 3 ft at 10 seconds and S around 2 ft at 16 seconds.
Fri..NW winds 20 to 30 kt with gusts up to 35 kt. Wind waves 6 to 7 ft. Mixed swell nw around 3 ft at 11 seconds and S around 2 ft at 16 seconds.
Fri night..NW winds 20 to 30 kt with gusts up to 35 kt. Wind waves 4 to 5 ft. Mixed swell nw around 3 ft at 10 seconds and sw around 2 ft at 15 seconds.
Sat..SW winds 10 to 20 kt with gusts up to 25 kt. Wind waves 3 to 4 ft. Mixed swell nw around 3 ft at 10 seconds and S around 2 ft at 15 seconds. Rain likely.
Sat night..SW winds 15 to 20 kt with gusts up to 25 kt. Wind waves 2 to 3 ft. W swell 3 to 5 ft at 10 seconds and S around 2 ft at 14 seconds. A chance of rain.
Sun..SW winds 5 to 15 kt. Wind waves 3 to 4 ft. W swell 3 to 5 ft and S around 2 ft. Rain.
Mon..W winds up to 10 kt. Wind waves 1 to 2 ft. W swell 3 to 4 ft and S around 2 ft. A chance of rain.
...san francisco bar/fourfathom bank forecast..... In the deep water channel...seas 6 to 9 ft with a dominant period of 8 seconds. Across the bar...seas 6 to 9 ft with a dominant period of 8 seconds. Maximum ebb current of 2.2 kt at 11:49 am Thursday and 1.4 kt at 01:37 am Friday.
PZZ500 252 Am Pdt Thu Apr 2 2020
Synopsis for the central california coast and bays including the Monterey bay..Greater farallones...and cordell bank national marine sanctuaries... Moderate northwesterly winds will prevail again today over the coastal waters. Gusts could reach gale-force for some locations this afternoon and evening. These winds will produce fresh and steep wind-generated waves, creating hazardous conditions for smaller vessels. Winds will begin to subside late Friday. The swell will be mixed with both a northwest and southwest component through the weekend.


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


Area Discussion for - San Francisco/Monterey Bay Area, CA
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FXUS66 KMTR 021128 AFDMTR

Area Forecast Discussion National Weather Service San Francisco Bay Area 428 AM PDT Thu Apr 2 2020

SYNOPSIS. Sunny and mild today with highs in the 60s. Seasonably cool overnight with the coldest valleys still falling into the 30s Friday morning followed by another sunny and mild Friday afternoon. Rain develops in the North Bay Saturday morning and then spreads over the Bay Area Saturday afternoon with rain reaching the Central Coast by late afternoon/evening. A second system drops down the coast by early Sunday morning with another round of rain, isolated thunderstorms and gusty winds Sunday. Showers linger into Monday as the low slowly drops towards Southern California by Tuesday. More noted warming and drying develops by mid to late week.

DISCUSSION. as of 3:15 AM PDT Thursday . Skies are mostly clear this morning with a strong 6.5 mb northerly gradient down the coast. This is keeping the atmosphere fairly well mixed so far tonight with temps currently running in the 40s to around 50 regionwide. Some of the hill locations are reporting northeast wind gusts to around 20 mph with the dry northerly flow keeping skies mostly clear. This will set the stage for a sunny and mild Thursday with highs warming into the mid and upper 60s, aided by some downslope winds across the North and East Bay this morning before winds turn more onshore later this afternoon.

One more clear and cool night with some of the interior valleys dropping into the mid/upper 30s but most areas staying in the 40s once again for Friday morning. Friday will remain dry with some increasing clouds ahead of the weekend system. Increasing onshore winds will knock temperatures down a few degrees but low to mid 60s should prevail.

Main weather focus is then on a wet Bay Area weekend. Models have slightly slowed the onset of rain Saturday morning. Its interesting to watch the models resolve the two shortwaves, currently up in the Gulf of Alaska and Aleutian Islands. The lead shortwave will reach the North Bay by Saturday morning with rain gradually spreading over the Bay Area Saturday afternoon. Per usual, the front will weaken as it reaches the Santa Clara Valley with just some light rain for the South Bay and Monterey Bay region by later Saturday afternoon/evening. Rain totals by Saturday evening look to be 0.25-0.50 for the North Bay, 0.25 Bay Area and tenth or so for the South Bay/Monterey Bay region (locally higher Santa Lucias).

The second shortwave will drop down the coast by early Sunday morning. The two systems will do a little Fujiwhara dance and there wont be much of a break as steady rain redevelops across the region by Sunday morning. An incoming jet streak will provide good diffluence aloft with cold air aloft allowing for steep lapse rates with a fairly well defined surface boundary. By Sunday afternoon showers and or isolated thunderstorms with small hail will be likely as snow levels drop to around 3500 feet. Will say that latest model solutions keep the coldest pool farther offshore so snow levels look slightly higher than they did 24 hours ago. The position of the upper low and cold air aloft sets the stage for some likely strong t-storm activity in the Central Valley with potentially interesting shear profiles due to strong low level wind flow driven by the topography in combination with increasingly strong April sun angle to help with afternoon destabilization. Still too far out for finer details but limiting factor for strong storms in our CWA on Sunday may be extensive cloud cover.

Shower activity will last Sunday night into Monday as the core of the upper low passes over the region with isolated t-storm threat continuing. Latest qpf forecasts from Saturday through Monday suggest 0.50-1.00 on average for most of the Bay Area with 1-2 inch totals for the favored hills of coastal Sonoma/Santa Cruz mtns and Santa Lucia range. Similar to the previous cold core systems in late March the more likely scenario is for this system to over perform in terms of final rainfall totals.

Low will be slow to exit the region with showers possibly persisting for the Central Coast thru Tuesday. High pressure slowly builds midweek and beyond with gradual warming and drying trend. Extended model trends indicate at least more light rain chances should continue through mid-month behind the late week ridge. Not nearly enough to make up for the February deficits but welcome rain nonetheless that at the very least delays the start of fire season, puts some extra snowpack in the Sierra and some more water in the reservoirs.

AVIATION. as of 4:29 AM PDT Thursday . For 12Z TAFs. Mostly clear skies with VFR conditions have been observed this early morning throughout the San Francisco Bay Area. A solid 6.0+ mb northerly pressure gradient is in place from Arcata to San Francisco, helping to keep the boundary layer well-mixed. The drier air is reflected well in the surface dewpoint observations, as they have trended downward by 3 to 7 degrees (or more) for most locations compared to this time yesterday. Thus, do expect VFR conditions to prevail at the terminals through the day. Light winds this morning will increase this afternoon, becoming gusty at the wind-prone terminals.

Vicinity of KSFO . VFR conditions are forecast to prevail today with mostly clear skies. Light winds this morning will increase out of the west/northwest through the day, becoming breezy by the afternoon. Sustained winds at/above 20 kt with gusts over 25 kt are quite conceivable.

SFO Bridge Approach . Similar to KSFO.

Monterey Bay Terminals . The patchy low clouds from Wednesday evening have mixed-out overnight, leaving behind mostly clear skies with VFR conditions at both MRY and SNS. Light winds this morning will become west/northwest this afternoon around 12-15 kt with the potential for some gusts, particularly at SNS.

MARINE. as of 2:52 AM PDT Thursday . Moderate northwesterly winds will prevail again today over the coastal waters. Gusts could reach gale-force for some locations this afternoon and evening. These winds will produce fresh and steep wind-generated waves, creating hazardous conditions for smaller vessels. Winds will begin to subside late Friday. The swell will be mixed with both a northwest and southwest component through the weekend.

MTR WATCHES/WARNINGS/ADVISORIES. Tday. SCA . Pigeon Pt to Pt Pinos 0-10 nm from 1 PM SCA . Pt Arena to Pt Reyes 0-10 nm SCA . Pt Reyes to Pigeon Pt 0-10 nm SCA . Pt Pinos to Pt Piedras Blancas 0-10 nm SCA . Pt Arena to Pigeon Pt 10-60 nm SCA . Pigeon Pt to Pt Piedras Blancas 10-60 nm SCA . Mry Bay from 3 PM SCA . SF Bay from 3 PM



PUBLIC FORECAST: RWW AVIATION: Rowe MARINE: Rowe

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Weather Reporting Stations
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Stations Dist Age Wind Air TempWater Temp WavesPressureDewPt
RTYC1 - 9414523 - Redwood City, CA 14 mi73 min Calm G 1.9 47°F 60°F1019.1 hPa (+1.2)
46012 - HALF MOON BAY - 24NM South Southwest of San Francisco, CA 23 mi43 min NNW 21 G 25 51°F 55°F1019.5 hPa44°F
46237 - San Francisco Bar, CA (142) 23 mi73 min 53°F5 ft
AAMC1 - 9414750 - Alameda, CA 23 mi73 min NW 4.1 G 6 49°F 59°F1018.7 hPa (+1.2)
PXSC1 23 mi73 min 51°F 39°F
FTPC1 - 9414290 - San Francisco, CA 23 mi73 min 59°F
PXOC1 - 9414311 - San Francisco (Pier 1), CA 23 mi73 min W 2.9 G 4.1 50°F 1017.8 hPa (+1.2)
OBXC1 24 mi73 min 50°F 40°F
OMHC1 - 9414769 - Oakland Middle Harbor Met, CA 24 mi73 min N 8 G 9.9
OKXC1 - 9414776 - Oakland (Berth 34), CA 25 mi73 min N 8.9 G 9.9 50°F 1018.8 hPa (+1.2)
LNDC1 25 mi73 min NNW 5.1 G 7 49°F 1018.6 hPa (+1.2)
46026 - SAN FRANCISCO - 18NM West of San Francisco, CA 27 mi43 min NW 14 G 18 51°F 53°F1019.7 hPa
TIBC1 - Tiburon Pier, San Francisco Bay, CA 29 mi57 min WSW 1.9 47°F 1019 hPa
PPXC1 - 9414847 - Richmond (Point Potrero), CA 31 mi73 min N 6 G 9.9 49°F 1019 hPa (+1.2)
RCMC1 - 9414863 - Richmond, CA 32 mi73 min N 8 G 9.9 50°F 56°F1018.4 hPa (+1.2)
DPXC1 - 9415141 - Davis Point, San Pablo Bay, CA 42 mi73 min W 5.1 G 6 49°F 1018.6 hPa (+1.2)
MZXC1 - 9415102 - Martinez-Amorco CA 43 mi73 min S 1 G 1.9 46°F 57°F1018.7 hPa (+1.3)
UPBC1 44 mi73 min NW 1.9 G 2.9
PCOC1 - 9415144 - Port Chicago, CA 47 mi73 min S 6 G 7 44°F 57°F1018.3 hPa (+1.2)
46042 - MONTEREY - 27NM West of Monterey Bay, CA 48 mi43 min NNW 18 G 21 53°F 56°F1018.4 hPa46°F

Wind History for Redwood City, CA
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Airport Reports
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AirportDistAgeWind ktVisibilitySky/WeatherTempDewPtHumidityPressure
Half Moon Bay Airport, CA3 mi18 minN 97.00 miFair48°F42°F82%1019.3 hPa
San Francisco, San Francisco International Airport, CA12 mi17 minWNW 610.00 miFair49°F41°F74%1019.1 hPa
San Carlos Airport, CA13 mi73 minN 010.00 miFair45°F39°F81%1019 hPa
Palo Alto Airport, CA19 mi26 minN 010.00 miClear45°F39°F81%1019.3 hPa
Oakland, Metro Oakland International Airport, CA21 mi20 minN 010.00 miFair48°F41°F77%1019.3 hPa
Hayward, Hayward Air Terminal, CA23 mi19 minENE 510.00 miFair45°F37°F74%1020 hPa

Link to 5 minute data for KSFO

Wind History from SFO (wind in knots)
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1 day agoCalmW3E3E5NW12W11W16W13
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2 days agoSE4E4NE5NE6E6NE3W10W12W14W14W13W11W6SW4W4W3SW4SW3CalmNW3W5NW6CalmS4

Tide / Current Tables for Half Moon Bay, California
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Half Moon Bay
Click for Map
Thu -- 12:06 AM PDT     3.22 feet Low Tide
Thu -- 03:31 AM PDT     Moonset
Thu -- 05:31 AM PDT     4.83 feet High Tide
Thu -- 06:52 AM PDT     Sunrise
Thu -- 12:56 PM PDT     -0.03 feet Low Tide
Thu -- 01:26 PM PDT     Moonrise
Thu -- 07:34 PM PDT     Sunset
Thu -- 08:20 PM PDT     4.16 feet High Tide
Tide / Current data from XTide NOT FOR NAVIGATION
Sorry tide depth graphs only, please select another station.

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3.23.33.64.14.54.84.84.43.72.71.60.70.1-00.20.71.52.33.23.84.14.13.83.4

Tide / Current Tables for San Mateo Bridge, South San Francisco Bay, California Current
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San Mateo Bridge
Click for Map
Thu -- 12:19 AM PDT     -0.60 knots Max Ebb
Thu -- 03:21 AM PDT     0.00 knots Slack
Thu -- 03:30 AM PDT     Moonset
Thu -- 05:48 AM PDT     0.78 knots Max Flood
Thu -- 06:51 AM PDT     Sunrise
Thu -- 08:44 AM PDT     -0.00 knots Slack
Thu -- 12:32 PM PDT     -1.50 knots Max Ebb
Thu -- 01:25 PM PDT     Moonrise
Thu -- 04:10 PM PDT     0.00 knots Slack
Thu -- 07:11 PM PDT     1.53 knots Max Flood
Thu -- 07:33 PM PDT     Sunset
Thu -- 10:50 PM PDT     -0.01 knots Slack
Tide / Current data from XTide NOT FOR NAVIGATION
Sorry tide depth graphs only, please select another station.

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-0.6-0.5-0.3-0.10.30.70.80.60.3-0.1-0.6-1.1-1.5-1.5-1.1-0.7-0.10.71.31.51.51.20.6-0.1

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.
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Other links: Northern Pacific     Contential US     Full GOES-East
Wind Forecast for San Francisco/Monterey Bay Area, CA (11,2,3,4)
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Ground Weather Radar Station San Francisco Bay Area, CA
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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.