Saturday, August15, 2020
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Marine Weather and Tides
San Leandro, 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 6:23AMSunset 8:02PM Saturday August 15, 2020 9:37 AM PDT (16:37 UTC) Moonrise 1:36AMMoonset 4:50PM Illumination 11% Phase: Waning Crescent; Moon at 26 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- 814 Am Pdt Sat Aug 15 2020
Today..NW winds 5 to 15 kt.
Tonight..W winds 5 to 15 kt. A slight chance of showers and Thunderstorms.
Sun..W winds 5 to 15 kt. A slight chance of showers and Thunderstorms.
Sun night..W winds 5 to 15 kt.
Mon..W winds 10 to 20 kt with gusts up to 25 kt.
Mon night..W winds 5 to 15 kt.
Tue..W winds 10 to 20 kt with gusts up to 25 kt.
Wed..W winds 10 to 20 kt with gusts up to 25 kt. Winds and wind waves higher in and near Thunderstorms.
PZZ500 814 Am Pdt Sat Aug 15 2020
Synopsis for the central california coast and bays including the Monterey bay..Greater farallones...and cordell bank national marine sanctuaries... Light west to northwest winds will prevail across the coastal waters this morning. Locally breezy afternoon and evening winds are expected along coastal gaps, particularly near santa cruz and along the big sur coast south of point sur. There will be a slight chance of scattered Thunderstorms tonight and tomorrow over the waters, mainly for the southern waters. Winds will increase slightly early next week as high pressure builds off the coast. Mixed seas will continue with a short period northwest swell and a couple of longer period southerly swells.


7 Day Forecast for Marine Location Near San Leandro, CA
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location: 37.68, -122.17     debug


Area Discussion for - San Francisco/Monterey Bay Area, CA
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FXUS66 KMTR 151144 AFDMTR

Area Forecast Discussion National Weather Service San Francisco Bay Area 444 AM PDT Sat Aug 15 2020

SYNOPSIS. Dangerously hot temperatures with Excessive Heat Warnings inland and Heat Advisories around the Bay with record or near record heat possible again today. Little relief along the coast as the marine layer will be very shallow with only light onshore breezes. Isolated dry lightning is also possible across the region late today into early Sunday. The ridge responsible for the hot weather will stay in place through next week.

DISCUSSION. as of 3:45 AM PDT Saturday . An oppressive, prolonged heatwave is now underway not only for our local area but across much of the western CONUS. Widespread record breaking temperatures were observed yesterday regionwide and afternoon temperatures easily exceeded triple digits readings across the interior with pockets of mid 90s to around 100 even near the coast. Forecast model data has struggled to keep up with this oppressive heat along the coastal interface and as a result the forecast will constantly be reevaluated and action taken as necessary. An afternoon sea breeze did eventually pick up along the immediate coast mid to late yesterday afternoon which helped to bring some limiting cooling, however, many areas away from the coast or at higher elevations are still struggling to cool overnight. This lack of overnight cooling relief can lead to accumulating heat stress and should be taken seriously during prolonged heat events such as this one.

At the synoptic scale, there are two primary weather systems that will play a role in our weather through the weekend. The first and most prominent is the 597dm 500mb high pressure system centered roughly over Arizona which is slowly expanding into California from the southeast. Hot stagnant air trapped beneath this dome of high pressure first encroached on the region Thursday night which then set the stage for Fridays historic heat which broke temperature records across the region. This high pressure system will gradually strengthen to 600dm at 500mb as it retrogrades towards Vegas and further builds into the local area through next week, resulting in continued oppressive heat, especially across the interior through next week. To the west, a 579dm 500mb low pressure system is colliding with the northwestern perimeter of the oppressive high pressure ridge. This low pressure system will bring about a brief cooling trend between Friday and Saturday and again on Saturday on Sunday as it nudges the perimeter of the hot dry air under the ridge farther eastward, likely making Sunday the coolest day throughout the entirety of the prolonged heatwave. However, as this occurs, a surge of moisture at 700-500mb aloft will be advected in from the south in the southerly flow between these features later today, tonight, and into Sunday morning. Elevated convective parameters meet critical thresholds to spark the potential for fast moving, high based convection of which some isolated thunderstorms may develop and move across the area from south to north. Given the dry fuels and hot, drying air mass in place, any isolated lightning strikes could lead to new wildfire starts. In addition, due to both the high based and fast northward progression, little if any precipitation will accompany lightning strikes at the surface, suggesting that isolated dry lightning will be the main outcome of any elevated convection through the coming days. As a result, in coordination with the neighboring offices, a fire weather watch has been issued for the potential of isolated dry lightning Saturday PM to Sunday AM. Those paying close attention may notice that there are two fire weather watches for our area, which have been segmented by GACC coverage (regional fire offices) and likely timing of arrival of highest MUCAPE/Modified Total Totals/PWAT values.

Lightning risk aside, heat risk will be the broader societal impact again on Saturday. The excessive heat watches across the interior (including the urban areas of the East and South Bay valleys) continue to remain in effect through the prolonged heatwave with expected peak temperature for today again in the low to mid 100s, locally in the upper 100s. In addition to the excessive heat warning across the interior, we plan to issue targeted daily heat advisories for the nearshore and coastal zones as needed. Friday showed how oppressive this heatwave can be and even the highest ensemble members of the hottest forecast models struggled to encapsulate the full extent of yesterdays record breaking heat along the coastal to inland interface. Given this experience and the warm overnight temperatures in place to start the day today, made several passes on the forecast temperatures and nudged nearly all of Saturday's forecast temperatures higher in the coastally influenced sites that may have been too cool. Noticeably warmer temperatures are now in place for today along the San Francisco Bayshore and for the city itself, however, Saturday is not expected to be nearly as hot as Friday by a margin of a few to several degrees, though not many days are capable of such heat. As such, heat advisories are in place for today for all of the same locations they were in place by the last update around lunchtime yesterday. This includes, the North Bay valleys including Santa Rosa and Napa, the San Francisco Bayshore, including Oakland and Silicon Valley, San Francisco itself, the Santa Cruz mountains including Scotts Valley, the northern Monterey Bay including Santa Cruz and Watsonville, and the southern Monterey Bay including Big Sur. Some locations in today's heat advisory may not fall within criteria of the heat advisory however other portions of a zone will, ie Big Sur Station will likely be much warmer than Pacific Grove. Likewise, the higher hills and east to southeastern portion of San Francisco are much warmer than the west side of town. Overall, these temperatures are 10 to 25 degrees above seasonal normals, depending on the location.

The most important weather shift to watch for today will be subtle shifts in wind direction as afternoon sea breezes are expected to develop once again this afternoon. As with many previous heat events, coastally influenced communities may hit their maximum daytime temperature as early as 1130am before winds shift onshore and cooler air from the nearshore waters advects in and begins to counterbalance the warmer air inland. This occurred yesterday at Carmel, for example, which peaked in the mid 90s before noon when the wind shifted. For today, watching for wind shifts towards the west will be key in determining maximum temperatures for the day and is one key reason days like yesterday are difficult to nail both for the models and human forecasters, as even the slightest of onshore breezes result in significant temperature shifts over the course of an hour or two.

Looking ahead, the upper low off the coast weakens and is ejected out of the area late Sunday into early Monday which allows the high pressure system to further strengthen and recenter itself north of Vegas over the Great Basin. Consequently, high pressure will be in total control of the weather pattern and hot stagnant air will result in increasing temperatures from Monday into mid week next week, likely the next peak in the prolonged heat wave. This forecast shift nudged up the forecast maximum temperatures somewhat for the Tuesday to Wednesday timeframe however expect further increases as we near this time frame. Medium to long term models suggest a potential for this high pressure to remain the primary weather driver across the western CONUS through next weekend. We will continue to closely monitor both the heat and fire weather risk over the coming week and add or update any watches, warnings, and advisories as the data requires it. Generally after a few days of extreme heat, we see hints of a southerly wind reversal and return of a shallow but vigorous marine layer first over the Central Coast and then into Bay Area, however, still nothing of that sort expected in the nearterm.

AVIATION. as of 04:42 AM PDT Friday . for 12Z TAFs. VFR through the TAF period. Winds are currently light, but Saturday afternoon will see traditional onshore breezy conditions, before subsiding at night. As monsoonal moisture continues to move over the region on Saturday, high clouds are expected across the sky. There is a slight chance for an isolated elevated shower Saturday afternoon, but there is low confidence and should mostly be over the ocean or far enough to the east.

Vicinity of KSFO . VFR. Light, onshore winds, will begin to increase and become breezy Saturday afternoon. High clouds are expected over the terminal for much of the day, but remaining VFR throughout the TAF period with subsiding winds Saturday evening. Low confidence in the chance for storm development, but VCTS was added to KLVK as models are showing some development in the eastern portion of the region in the late afternoon. Storm development will be monitored and removed if necessary.

SFO Bridge Approach . Similar to KSFO.

Monterey Bay Terminals . VFR with calm winds. As moisture from the south moves over the area, expect increasing number of high clouds, but the terminals will remain VFR through Saturday. Winds will increase and become breezy Saturday afternoon. With the influx of moisture, models have indicated a chance for isolated storms popping up, but there is low confidence in it developing. A VCTS group was added to KSNS for Saturday afternoon, and will be monitored/removed if storms end up not forming.

CLIMATE. Record High Temperatures with the upcoming heat event. August 15 August 16 ----------------------------------------- Santa Rosa 103, 2019; 100, 2019; Kentfield 101, 2019; 101, 2015; Napa 102, 1906; 104, 2015; Richmond 91, 2019; 94, 2015; Livermore 108, 1967; 105, 1951; San Francisco 87, 1950; 90, 2015; SFO 94, 2019; 90, 2015; Redwood City 100, 2019; 101, 2015; Half Moon Bay 71, 1984; 72, 2015; Oakland Dtown 93, 2015; 92, 2015; San Jose 99, 2019; 97, 2015; Gilroy 104, 2019; 107, 2019; Santa Cruz 101, 2015; 94, 1983; Salinas 93, 2015; 94, 1933; Monterey 90, 2015; 83, 2015; King City 104, 1950; 103, 2015;

MARINE. as of 02:31 AM PDT Saturday . Winds are currently light, but locally stronger afternoon and evening winds are expected along coastal gaps, particularly near Santa Cruz and along the Big Sur Coast south of Point Sur. There is a small chance of scattered showers late on Saturday, mostly over the southern waters. Winds will increase slightly early next week as high pressure starts to build off the California coast. Mixed seas will prevail with a persistent small period northwest swell and a longer period southerly swell.

MTR WATCHES/WARNINGS/ADVISORIES. Tday. Excessive Heat Warning . CAZ507-510-511-513-516>518 Fire Weather Watch . CAZ516>518-528-530 Heat Advisory . CAZ006-506-508-512-528>530 SCA . Pigeon Pt to Pt Pinos 0-10 nm from 3 PM SCA . Pt Pinos to Pt Piedras Blancas 0-10 nm from 3 PM



PUBLIC FORECAST: DRP AVIATION: DK MARINE: DK

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Weather Reporting Stations
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Stations Dist Age Wind Air TempWater Temp WavesPressureDewPt
AAMC1 - 9414750 - Alameda, CA 9 mi50 min 69°F
LNDC1 10 mi50 min N 4.1 G 5.1 71°F 1012.5 hPa
OMHC1 - 9414769 - Oakland Middle Harbor Met, CA 12 mi50 min NNW 2.9 G 4.1
RTYC1 - 9414523 - Redwood City, CA 12 mi50 min NW 1 G 1.9 73°F 77°F1013.1 hPa
OBXC1 12 mi50 min 67°F 64°F
OKXC1 - 9414776 - Oakland (Berth 34), CA 13 mi50 min NW 5.1 G 6 66°F 1012.6 hPa
PXOC1 - 9414311 - San Francisco (Pier 1), CA 14 mi50 min NW 2.9 G 6 71°F 1011.6 hPa
PXSC1 15 mi50 min 70°F 61°F
FTPC1 - 9414290 - San Francisco, CA 18 mi50 min 66°F
PPXC1 - 9414847 - Richmond (Point Potrero), CA 19 mi50 min SSW 6 G 8.9 66°F 1012.9 hPa
TIBC1 - Tiburon Pier, San Francisco Bay, CA 21 mi74 min Calm 74°F 1013 hPa
RCMC1 - 9414863 - Richmond, CA 21 mi50 min 67°F
UPBC1 25 mi50 min NW 12 G 17
MZXC1 - 9415102 - Martinez-Amorco CA 25 mi50 min WNW 14 G 17 75°F 71°F1011.7 hPa
DPXC1 - 9415141 - Davis Point, San Pablo Bay, CA 26 mi50 min WSW 7 G 8.9 71°F 1012.1 hPa
46237 - San Francisco Bar, CA (142) 26 mi68 min 61°F2 ft
PCOC1 - 9415144 - Port Chicago, CA 27 mi50 min W 13 G 15 74°F 71°F1011.5 hPa
PSBC1 - 9415115 - Pittsburg (Suisun Bay), CA 29 mi50 min NW 9.9 G 14 76°F 1011.1 hPa
46026 - SAN FRANCISCO - 18NM West of San Francisco, CA 36 mi38 min WSW 1.9 G 3.9 59°F 1013.1 hPa (+0.8)59°F
SFXC1 - San Francisco Bay Reserve, CA 37 mi113 min NW 5.1
46012 - HALF MOON BAY - 24NM South Southwest of San Francisco, CA 44 mi38 min W 1.9 G 3.9 63°F 1013 hPa62°F

Wind History for Alameda, CA
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Airport Reports
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AirportDistAgeWind ktVisibilitySky/WeatherTempDewPtHumidityPressure
Hayward, Hayward Air Terminal, CA3 mi44 minN 010.00 miFair82°F53°F37%1013 hPa
Oakland, Metro Oakland International Airport, CA3 mi45 minW 610.00 miA Few Clouds77°F57°F52%1012.5 hPa
San Carlos Airport, CA11 mi51 minVar 410.00 miClear73°F62°F69%1012.9 hPa
San Francisco, San Francisco International Airport, CA11 mi42 minE 310.00 miA Few Clouds73°F61°F66%1012.3 hPa
Palo Alto Airport, CA14 mi51 minN 010.00 miA Few Clouds75°F62°F65%1012.5 hPa
Mountain View, Moffett Field, CA18 mi2.7 hrsN 010.00 miFair72°F62°F73%1011.8 hPa
Livermore, Livermore Municipal Airport, CA19 mi45 minWNW 310.00 miFair82°F54°F38%1011.7 hPa
Half Moon Bay Airport, CA21 mi43 minNW 67.00 miFair70°F57°F64%1012.9 hPa
Concord, Buchanan Field, CA22 mi45 minNNW 510.00 miFair82°F55°F40%1010.3 hPa

Link to 5 minute data for KOAK

Wind History from OAK (wind in knots)
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Last 24hrW5W6W6NW10NW11NW12NW9NW11NW12NW8NW10NW6W5NW3S3NW4NW5NW4N4NW3NW7N4NW4W6
1 day agoW64SW4W8NW10NW8NW10NW11NW11NW13NW9N3W5NW6N3SW4CalmNW5CalmNE3SW4NW4CalmCalm
2 days agoNW6W6W7NW10NW12NW12NW12NW12W10NW11NW9NW7NW7NW7CalmNW8CalmN3N3CalmCalmN4NW4Calm

Tide / Current Tables for Roberts Landing, 1.3 miles west of, San Francisco Bay, California
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Roberts Landing
Click for Map
Sat -- 02:35 AM PDT     Moonrise
Sat -- 05:07 AM PDT     0.24 feet Low Tide
Sat -- 06:24 AM PDT     Sunrise
Sat -- 11:56 AM PDT     5.83 feet High Tide
Sat -- 04:43 PM PDT     3.26 feet Low Tide
Sat -- 05:49 PM PDT     Moonset
Sat -- 08:00 PM PDT     Sunset
Sat -- 10:09 PM PDT     7.57 feet High Tide
Tide / Current data from XTide NOT FOR NAVIGATION
Sorry tide depth graphs only, please select another station.

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5.54.12.61.40.60.20.51.22.33.64.75.65.85.54.843.43.33.84.8677.67.4

Tide / Current Tables for Oakland Airport SW, South San Francisco Bay, California Current
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Oakland Airport SW
Click for Map
Sat -- 12:36 AM PDT     -0.77 knots Max Ebb
Sat -- 02:35 AM PDT     Moonrise
Sat -- 04:40 AM PDT     0.01 knots Slack
Sat -- 06:25 AM PDT     Sunrise
Sat -- 08:06 AM PDT     0.58 knots Max Flood
Sat -- 11:21 AM PDT     -0.00 knots Slack
Sat -- 01:17 PM PDT     -0.32 knots Max Ebb
Sat -- 04:23 PM PDT     0.00 knots Slack
Sat -- 05:49 PM PDT     Moonset
Sat -- 07:27 PM PDT     0.43 knots Max Flood
Sat -- 08:00 PM PDT     Sunset
Sat -- 10:15 PM PDT     -0.00 knots Slack
Tide / Current data from XTide NOT FOR NAVIGATION
Sorry tide depth graphs only, please select another station.

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-0.7-0.8-0.6-0.5-0.20.10.40.50.60.50.40.1-0.2-0.3-0.3-0.2-0.10.10.30.40.40.30.1-0.3

Weather Map
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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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Wind Forecast for San Francisco/Monterey Bay Area, CA (12,3,4,5)
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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.