Tuesday, March20, 2018 L-36.com

Marine Weather and Tides
Point Arena, CA

Version 3.4
What's New / NOTES
3/3/2018 - There is a new GOES Satellite for the east coast that required rewriting that part of the code. Please report any issues.
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.

Sunrise 7:10AMSunset 7:23PM Tuesday March 20, 2018 6:21 PM PDT (01:21 UTC) Moonrise 8:36AMMoonset 10:08PM Illumination 18% Phase: Waxing Crescent; Moon at 4 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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7 Day Forecast for Marine Location Near Point Arena, CA
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location: 36.95, -126.32     debug

Area Discussion for - San Francisco/Monterey Bay Area, CA
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Fxus66 kmtr 210000
area forecast discussion
national weather service san francisco bay area
500 pm pdt Tue mar 20 2018

Synopsis A series of storm systems and atmospheric river aimed
at the central and southern california coast will produce
widespread rainfall across our region today through Thursday.

Periods of heavy rain are possible, mainly along the big sur
coast, as well as locally strong southerly winds and isolated
thunderstorms. Showers will linger on Friday and Saturday with dry
conditions returning by Sunday.

Discussion As of 02:00 pm pdt Tuesday... Afternoon radar
imagery and satellite imagery pretty much says it all,
precipitation has spread across the entire bay area. Rainfall
amounts since this morning have been highest over the higher
mountains of the big sur. Six hour rainfall amounts have been just
over 0.5" along big sur with a few hundredths to two tenths
everywhere else. Given the cloud cover rain temperatures have
remained on the cool side and mostly in the 50s. Did lower some of
the forecast MAX temps for today.

For the rest of today and into this evening - latest hi-res models
continue to advect in some much higher pwats translating to
increased rainfall rates. Blended total precipitable water
satellite imagery SW of the big sur ranges from 1.5-1.7", which is
over 200% of normal. Taking a closer look at the ar monitoring
system at pt sur indicate a real ramp up of integrated water vapor
(iwv) and upslope iwv flux from 22-03z. That being said, rain will
be heaviest during that timeframe. North of monterey, rain will
increase as well, but not as intense at the coastal mountains.

Impacts could be ponding on roads and slower commute times this
afternoon evening. After about 03-05z it looks like the main
moisture plume drifts southward leading to decreasing rain rates
and possibly more showery precip late tonight early Wednesday. It
should be note that guidance continues to show a pulse of
moisture interacting with a weak shortwave over the north bay this
evening overnight, which may result in some enhance precip

Wednesday is still forecast to start off with less rainfall, but
still light to moderate for many locations. Given the ample low
level moisture and decent southwesterly flow orographically
favored spots may see moderate to possibly heavy rains at times.

As the main low trough off the coast begins to march eastward rain
is expected to increase in short order late Wednesday
afternoon evening. As this happens, high pwats to the south will
slowly begin to creep northward with greatest impact over the big
sur coast again. Additionally, nam GFS wrf all show instability in
the afternoon with a few hundred cape. Will keep thunder in for
the afternoon evening hours. One limiting factor could be the
amount of daytime heating with cloud cover.

The increasing pwats will gain additional support as the main
upper trough moves to the coastline late Wednesday night early
Thursday. This period will be the greatest concern for any
localized flooding due to saturated ground from today's rain and
additional heavy rain. This timeframe will also be the most likely
period for rapidly accumulating rainfall. Moderate to heavy
rainfall will diminish gradually during the day Thursday as a cold
front begins to move through. The cold front will provide a
renewed chance for thunderstorms Thursday afternoon evening.

Besides the rain impacts, wind will also impact the region. Winds
will increase late tonight early Wednesday from the south. Winds
will peak Wednesday night into Thursday with gusts of 30 to 45
mph. Strongest along the coast and higher peaks around the bay
area. Still on the fence for a wind advisory, but if one is issued
it would be Wednesday night.

Rainfall totals have not changed much earlier forecast. Amounts
are still 0.50" to 1.50" in most urban areas with the lesser
amounts in rain shadowed valley locations such as san jose to
higher amounts along the coast and in the north bay. Look for
1.00" to 3.00" inches in the coastal mountains of the bay area
with isolated higher amounts upwards of 4.00" or more in the santa
cruz mountains. The greatest rainfall totals will be along the
coastal ranges of the santa lucia mountains where 3.00" to 6.00"
will be likely with isolated amounts approaching 10.00". For what
it's worth one hi-res model shows 16" for big sur coast, but that
is an outlier. The greatest potential for small stream flooding
and mudslides, rock slides and debris flows will be along the big
sur coast.

Scattered showers will be possible Friday into Saturday as a weak
upper level trough moves over the region. Drier weather is
expected Sunday into Monday with warmer temperatures.

Aviation As of 4:30 pm pdt Tuesday... Occasional rain has been
falling in the sfo bay area while steadier rains have fallen in
the mry bay area. Radar indicates a break in the action this
evening as the rain band pushes south of the district. Moist
unstable air will allow showers to redevelop on Wednesday once
there is some daytime heating. Thunderstorms are not out of the
question for Wednesday afternoon but more likely they will be east
of the district.

East to southeast winds is forecast to continue through Thursday.

Surface winds have been 10 kt or less except for gusty winds to
30 kt in the salinas valley and 25 kt in the santa clara valley
will affect sjc and sns. Winds up to 35 kt above 925 mb could
produce llws tonight. CIGS will continue to be tricky to forecast.

Currently CIGS are MVFR in the sfo bay area and there is low
confidence on whether it will stay MVFR tonight or rise back up.

Vicinity of ksfo... MVFR conditions expected through Wednesday but
confidence is low... CIGS could lift above 3000 feet during the
night. Showers should decrease after dark but pick up again
during the day Wednesday. East to southeast winds to 10 kt.

Sfo bridge approach... Similar to ksfo.

Monterey bay terminals...VFR for CIGS remaining above 5000 ft.

Rain will decrease after 04z as rain band shifts south. Showers
should develop Wednesday due to daytime heating. Locally strong
gusts to 30 kt in the salinas valley impacting sns.

Marine As of 04:44 pm pdt Tuesday... Breezy and gusty southerly
winds will persist through the next couple of days as a strong
area of low pressure approaches from the west. These winds will
generate fresh southerly swell, which will mix in with a
northwest swell, creating seas rough and hazardous through at
least Thursday. A cold front will pass over the waters beginning
Thursday morning and will switch winds out of the nw. Rain and
showers will be possible through Saturday, with a slight chance
of thunderstorms on Thursday.

Mtr watches warnings advisories
Tday Sca... Pt arena to pt reyes 0-10 nm
sca... Pt reyes to pigeon pt 0-10 nm
sca... Pigeon pt to pt pinos 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
public forecast: mm
aviation: W pi
marine: bam as
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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 (21,6,7,8)
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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 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.