Sunday, September19, 2021
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Marine Weather and Tides
Mountain House, CA

Version 3.4
NOTICE
3/30/2021 -- ANZ330 has been split into ANZ331 and ANZ332. Click EDIT in Marine Forecast and select your new zone.
1/26/2021 -- The West Coast Satellite images havd been updated. They now use GEOS-17.
1/1/2021 -- The 7 day forecast are now working well. Thank you NOAA for your support.

Sunrise 6:50AMSunset 7:08PM Sunday September 19, 2021 6:30 AM PDT (13:30 UTC) Moonrise 5:59PMMoonset 4:19AM Illumination 96% Phase: Waxing Gibbous; Moon at 13 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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PZZ530 San Pablo Bay, Suisun Bay, The West Delta And The San Francisco Bay North Of The Bay Bridge- 301 Am Pdt Sun Sep 19 2021
Today..W winds 5 to 10 kt, increasing to 15 to 20 kt with gusts up to 30 kt this afternoon.
Tonight..W winds 15 to 20 kt with gusts up to 25 kt.
Mon..W winds 10 to 15 kt.
Mon night..W winds 5 to 10 kt.
Tue..NE winds 10 to 15 kt.
Tue night..SW winds 5 to 10 kt.
Wed..SW winds 5 to 10 kt.
Thu..W winds 5 to 10 kt.
PZZ500 301 Am Pdt Sun Sep 19 2021
Synopsis for the central california coast and bays including the Monterey bay..Greater farallones...and cordell bank national marine sanctuaries... A weak frontal system is passing through the waters this morning. Light southerly winds will quickly shift back out of the northwest later this morning. Light showers over the waters will move out by mid day Sunday. Northwest winds will strengthen in the post frontal environment tomorrow afternoon, with hazardous seas conditions developing over much of the waters, particularly for smaller vessels. Mixed seas persist with a short period northwest swell and a weak longer period southerly swell. An additional longer period northwest swell will arrive around mid week.


7 Day Forecast for Marine Location Near Mountain House, CA
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location: 37.83, -121.57     debug


Area Discussion for - San Francisco/Monterey Bay Area, CA
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FXUS66 KMTR 191151 AFDMTR

Area Forecast Discussion National Weather Service San Francisco Bay Area 451 AM PDT Sun Sep 19 2021

SYNOPSIS. Light rain showers end overnight with a return to drier but still cool conditions Sunday. A rapid shift towards gusty offshore flow and warmer, drier conditions begins Sunday night through early next week. A fire weather watch is in effect for the potential for increased fire risk due to the drying conditions and gusty offshore winds from Sunday night through Tuesday morning.

DISCUSSION. as of 09:40 PM PDT Saturday . KMUX radar shows scattered showers continuing to move eastward over Sonoma and northern Marin Counties. A look at 12-hour precip totals shows fairly impressive amounts (~0.5 in) at northern coastal Sonoma sites where SSW winds provided orographic enhancement. Just over the border in Mendocino Co, 1+ inch totals have been measured. Farther south and in the Sonoma Valley, amounts are under a tenth of an inch, and generally a few hundredths or less. No bucket tips in downtown SF as of yet. Hi-res models show the potential for very light scattered showers making their way south through the SF Bay Area and into the Monterey Bay Area overnight. These areas might see a trace to a few hundredths.

Satellite night imagery reveals disjointed marine stratus over the coastal waters, with some stratus developing over coastal land areas. Also, a band of higher level clouds associated with the precip and frontal boundary is traversing North Bay. After the frontal boundary passes through, winds will shift to the northwest and clouds will scatter out, though marine stratus will likely linger through the morning. Temperatures will also moderate a bit Sunday as the upper trough over the coast moves inland, and a ridge builds over the eastern Pacific. Still, most areas will remain several degrees below daily normals. A stark transition to drier and warmer conditions with the development of offshore flow occurs overnight Sunday into Monday. Fire Weather Watch goes into effect for the North Bay Mountains and East Bay Hills Sunday at 11 p.m. Read discussion below for more details and for the weekly outlook.

PREV DISCUSSION. as of 02:30 PM PDT Saturday . The first fall-like system of the post-summer dry season has begun to impact the Pacific Northwest and northwestern California through midday today.

Remote sensing imagery shows a narrow, intense band of 200% of normal precipitable water values akin to an atmospheric river along a dynamic cold frontal boundary on the leading edge of this feature. Relatively high rainfall values in excess of 2 inches have been reported farther north near Eureka, CA as this weakening atmospheric river shifts southward towards the Bay Area with lower amounts elsewhere. The Scripps' Center for Western Weather and Water Extremes atmospheric river index rates this storm system as a AR 1 (of 5) for northwestern California (& AR 2-3 in the PacNW), but falls below atmospheric river criteria for our area as it descends south of Cape Mendocino towards the Bay Area through tonight.

This difference is due to the lack of upper level dynamics that are present farther north near the core of the storm, but are lost as the southern flank of the frontal boundary falls away from the parent feature. Instead, orographic lift will be the primary lifting mechanism to generate rainfall from this narrowing precipitable water plume, thus there has been a recent model trend to pull back rainfall amounts across the interior and rain shadowed areas in favor of increasing upslope amounts along the coastal ranges. For example, a few days ago, the forecast called for peak amounts of perhaps 1/3" along the North Bay coastal ranges, but increased that to 1/2" a day or two ago, and today, up to 2/3" is now in range for our wettest spots like Venado. This orographic upshift in the rainfall comes at the cost of a downshift elsewhere, with 0.10-0.15" for the North Bay valleys, 0.04-0.08" for the I80 Corridor and coastal Peninsula, and a few hundredths to a trace along the the remainder of the San Francisco Bayshore and coastal Central Coast. The southern and eastern peripheries of the interior are more likely to see no rain at all than even 0.01".

In terms of timing, the bulk of the rainfall is forecast to arrive between this evening and the overnight period, with the frontal band fragmenting up and the last showers dissipating by sunrise tomorrow morning. Breezy west to northwest winds will develop in the wake of the front later tomorrow afternoon.

The weather pattern will remain progressive and fall-like in the wake of this trough, with a rapid shift towards warmer, drier conditions into early next week in response to a high amplitude eastern pacific ridge building ashore in the wake of the weekend's storm system. This rapid shift will begin to unfold through the day on Sunday and be heralded in with the arrival gusty offshore flow down the western side of Sacramento Valley before funneling through the North and East Bay interior ranges beginning late tomorrow evening. Fuels are near or at record dry levels across these interior slopes, and if today/tonight's storm fails to bring sufficiently wetting rains, then critical fire weather conditions could present themselves as the humidity plummets through Sunday night into Monday morning.

Offshore winds are forecast to peak between 3 am and 9 am Monday morning, with sustained winds 15 to 25 mph with gusts to 30 to 40 mph, locally to 50 mph at ridge top levels. Some mix down to the lower elevations is expected Monday morning, with gusts to 15-20mph possible at places like the Napa valley. A warmer, drier air mass settles in through the day on Monday and, with offshore flow, daytime humidities plummet into the low to mid teens in the drier spots. Poor overnight humidity recoveries are expected for Monday night into Tuesday morning, though on the plus side, winds should be roughly only half as strong as the previous night. So, both Sunday night and Monday night's offshore wind events are borderline critical criteria for varying reasons. For now, no changes are planned for the fire weather watch until we review observational rainfall numbers tomorrow morning. From here, we will decide to cancel or upgrade some or all parts of the watch. For more information, please review the fire weather section written by one of our fire weather incident meteorologists below.

AVIATION. as of 05:10 AM PDT Sunday . For the 12z TAFs. A system is continuing to move southward through the area this morning. The FROPA is currently moving over the Bay Area, brining MVFR/IFR ceilings & -RA/DZ to KSFO/KOAK/KLVK/KSJC. MVFR ceilings ahead of the front for the Monterey terminals. FROPA should continue through, exiting the southern terminals by 18Z. Lower confidence on -RA for KMRY/KSNS as FROPA has been and will continue to weaken this morning. Breezy northwest winds build over coastal terminals this afternoon. VFR conditions return Sunday afternoon behind the front. Low confidence in stratus returning Sunday night into Monday morning, as models keep skies VFR.

Vicinity of KSFO . MVFR/IFR ceilings as the main body of a weak front currently pass through. Some light showers or drizzle will be possible. Winds are expected to shift more out of the W/NW tomorrow behind the front. VFR skies by 18Z, with low confidence on skies filling back in Sunday night.

KSFO Bridge Approach . Similar to KSFO.

Monterey Bay . MVFR/IFR conditions prevailing this morning. Some drizzle possible in the next few hours, most precipitation from the aforementioned cold front is not expected to make it this far south. VFR conditions anticipated by late tomorrow morning/early afternoon. Light to locally breezy onshore winds.

FIRE WEATHER. As of 3:34 AM PDT Saturday . Fire Weather Watch in effect for North and East Bay hills from 11 pm Sunday night through 11 am Tuesday. As noted above in the short term we do expect some wetting rains for coastal Sonoma county. Wetting rains for Napa and East Bay hills look unlikely at this time though a few hundredths is certainly possible. Did look at the updated fuels charts that literally just updated. For the North Bay the ERC readings are down from record highs but still running near the 97th percentile (though thats obviously not accounting for any precip we receive the next 24 hours). The Bay Area marine zones that are continuously impacted by the marine layer and thus higher humidity are actually now running below normal for this time of year. Finally the Diablo/Santa Cruz mountains are around the 90th percentile but will likely drop slightly over the next 24 hours.

Anyway, we'll be monitoring rainfall totals closely through Sunday morning. High confidence for warming and drying to start Sunday afternoon but the airmass being replaced is very moist as noted by the high PW values. Watch start time of 11 pm Sunday still looks good with latest NAM model showing an abrupt increase in northeast wind around 925 mb between 06-09z. Given the stability profile would expect most of the winds to stay at or above 2000 feet with gusts generally in the 30-40 mph range (50 mph Mt Saint Helena). RH values look to stay above 30% into Monday morning which may be a limiting factor. In addition should wetting rains occur across much of the North Bay that could put us out of Red Flag criteria for 24 hours after the rain ends.

High confidence for rapid warming and drying Monday as temps will quickly rebound into the upper 80s and 90s with humidity dropping into the teens as persistent but light offshore winds continue. The entire Bay Area will dry out Monday night into Tuesday but wind speeds look light as the strongest pressure gradient stays over the northern Sierra.

General trend looks to be above average temps and continued dry next week though the models are grappling with a potential cut- off low. The more likely scenario is a transient midweek system passes to our north with another potential offshore wind event late in the week followed by building high pressure and unseasonably warm and dry wx through the end of the month.

MARINE. as of 04:42 AM PDT Sunday . A weak frontal system is passing through the waters this morning. Light southerly winds will quickly shift back out of the northwest later this morning. Light showers over the waters will move out by mid day Sunday. Northwest winds will strengthen in the post frontal environment tomorrow afternoon, with hazardous seas conditions developing over much of the waters, particularly for smaller vessels. Mixed seas persist with a short period northwest swell and a weak longer period southerly swell. An additional longer period northwest swell will arrive around mid week.

MTR WATCHES/WARNINGS/ADVISORIES. Tday. SCA . Mry Bay from 2 PM SCA . Pigeon Pt to Pt Pinos 0-10 nm from 2 PM SCA . Pt Pinos to Pt Piedras Blancas 0-10 nm from 2 PM SCA . Pt Arena to Pt Reyes 0-10 nm from 2 PM



PUBLIC FORECAST: Lorber/DRP AVIATION: Dhuyvetter MARINE: AS FIRE WEATHER: RWW

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Weather Reporting Stations
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Stations Dist Age Wind Air TempWater Temp WavesPressureDewPt
PSBC1 - 9415115 - Pittsburg (Suisun Bay), CA 22 mi42 min W 6 G 8.9 63°F 1017.6 hPa
PCOC1 - 9415144 - Port Chicago, CA 29 mi42 min W 8.9 G 12 62°F 67°F1018.3 hPa
MZXC1 - 9415102 - Martinez-Amorco CA 33 mi42 min WNW 16 G 18 60°F 67°F1018.4 hPa
SFXC1 - San Francisco Bay Reserve, CA 35 mi105 min W 5.1 61°F 1018 hPa57°F
LNDC1 38 mi42 min WNW 2.9 G 4.1 61°F 1018.6 hPa
AAMC1 - 9414750 - Alameda, CA 39 mi42 min W 7 G 8.9 60°F 66°F1019 hPa
DPXC1 - 9415141 - Davis Point, San Pablo Bay, CA 40 mi42 min NW 15 G 17 60°F 1018.3 hPa
OKXC1 - 9414776 - Oakland (Berth 34), CA 40 mi42 min WNW 8.9 G 9.9 60°F 1018.7 hPa
OMHC1 - 9414769 - Oakland Middle Harbor Met, CA 40 mi42 min W 11 G 12
OBXC1 41 mi42 min 60°F
RTYC1 - 9414523 - Redwood City, CA 41 mi42 min WNW 8 G 9.9 62°F 1019.4 hPa
PPXC1 - 9414847 - Richmond (Point Potrero), CA 42 mi42 min WNW 12 G 16 62°F 1018.9 hPa
PXOC1 - 9414311 - San Francisco (Pier 1), CA 44 mi42 min WSW 6 G 8.9 58°F 1017.7 hPa
PXSC1 44 mi42 min 60°F 60°F
RCMC1 - 9414863 - Richmond, CA 45 mi48 min NW 7 G 9.9 61°F 64°F1018.9 hPa
FTPC1 - 9414290 - San Francisco, CA 48 mi42 min W 7 G 9.9 58°F 64°F1019.1 hPa

Wind History for Port Chicago, CA
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Airport Reports
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AirportDistAgeWind ktVisibilitySky/WeatherTempDewPtHumidityPressure
Livermore, Livermore Municipal Airport, CA16 mi37 minW 610.00 miMostly Cloudy61°F58°F90%1018 hPa
Stockton, Stockton Metropolitan Airport, CA18 mi35 minNNE 510.00 miOvercast64°F58°F81%1017.8 hPa

Link to 5 minute data for KLVK

Wind History from LVK (wind in knots)
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1 day agoW3S5S6CalmCalmW653W7NW12NW13W15NW13W15W12NW9W6W8W7W6S4SW11W4SW7
2 days agoW5SW3SW6SW4SW5NW6NW43NW11W15NW8NW11W14NW11W9NW8NW7NW7NW3NW6NW5NW5NW4NW4

Tide / Current Tables for Borden Highway Bridge, Old River, San Joaquin River, California
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Borden Highway Bridge
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Sun -- 05:19 AM PDT     Moonset
Sun -- 05:43 AM PDT     3.19 feet High Tide
Sun -- 06:51 AM PDT     Sunrise
Sun -- 12:48 PM PDT     -0.13 feet Low Tide
Sun -- 06:58 PM PDT     Moonrise
Sun -- 07:00 PM PDT     2.95 feet High Tide
Sun -- 07:07 PM PDT     Sunset
Tide / Current data from XTide NOT FOR NAVIGATION
Sorry tide depth graphs only, please select another station.

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0.81.11.62.22.83.13.22.92.41.710.4-0-0.10.20.81.52.22.82.92.82.31.71.2

Tide / Current Tables for Brandt Bridge, San Joaquin River, California Current
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Brandt Bridge
Click for Map
Sun -- 02:13 AM PDT     0.00 knots Slack
Sun -- 04:53 AM PDT     0.63 knots Max Flood
Sun -- 05:18 AM PDT     Moonset
Sun -- 06:50 AM PDT     Sunrise
Sun -- 07:20 AM PDT     -0.00 knots Slack
Sun -- 11:40 AM PDT     -1.16 knots Max Ebb
Sun -- 03:21 PM PDT     0.00 knots Slack
Sun -- 06:18 PM PDT     0.68 knots Max Flood
Sun -- 06:57 PM PDT     Moonrise
Sun -- 07:06 PM PDT     Sunset
Sun -- 08:49 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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-0.7-0.5-0.10.30.60.60.50.1-0.3-0.7-1-1.1-1.2-1-0.6-0.20.20.50.70.60.3-0.1-0.4-0.7

Weather Map
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GEOS Local Image of CentralWestCoast    EDIT
NOTE: This section has been updated as of 1/26/2021. If the image you are expecting is not showing, please let me know. You may use the EDIT function to update your location.
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