Thursday, August17, 2017

Marine Weather and Tides
Point Arena, CA

Version 3.4
What's New / NOTES
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.
5/19/2016 - There were issues with the 3 day airport observation history. I switched to another data source. Let me know if you see any issues with the data feeds.

Sunrise 6:27AMSunset 8:00PM Thursday August 17, 2017 12:25 PM PDT (19:25 UTC) Moonrise 1:25AMMoonset 3:59PM Illumination 21% Phase: Waning Crescent; Moon at 25 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 171722
area forecast discussion
national weather service san francisco bay area
1022 am pdt Thu aug 17 2017

Synopsis A gradual inland warming trend can be expected through
late week as high pressure builds over the region. Overnight and
morning clouds will also be common, especially near the coast and in
the adjacent valleys.

Discussion As of 08:43 am pdt Thursday... Marine layer holding
steady at around 2000 ft per the fort ord profiler. Less
extensive stratus coverage across the region this morning than
what we saw at this time yesterday. Expecting stratus to burn off
earlier today as well. Current temperatures are generally running
a few degrees warmer this morning as high pressure continues to
build over the eastern pacific. This trend of warming will
continue through the week, especially for inland areas. For
additional information please see previous forecast discussion.

Prev discussion As of 4:14 am pdt Thursday... Skies are clear thus far
over most of napa county, parts of the east bay and south bay, san
benito and interior monterey counties while stratus and fog blanket
the bays and the rest of the coast early this morning. The marine
layer depth is holding steady at 2,000 feet.

The marine inversion is fairly well developed and further strengthening
occurs today into Saturday as increasing subsidence in advance of a
594 decameter closed mid-upper level high centered approx 700 miles
west of the bay area produces large scale sinking and adiabatic warming.

Thermal ridging coincides with geopotential height ridging over norcal
today into at least the first part of the weekend, and per most recent
nam model output warming becomes focused over inland valleys and hills
especially over the bay area counties, and in particular over the north
bay Friday and Saturday. 925 mb level temperatures reach 28c over
north bay tonight and then 30c Friday night meaning temperatures in
the north bay hills and mountains will most likely hover in the
lower to middle 80s all night as the marine layer becomes
increasingly squashed under high pressure. With this in mind, am not
having a whole lot of confidence in daytime maximum temperature
guidance especially for north bay and east bay areas Friday and
Saturday; 90s to near 100 will probably be more common even closer
to the bays as the marine layer becomes increasingly compressed.

Eventually an active mid latitude zonal jet stream crossing the
lower 48 buckles ever so slightly causing a weak and slowly sw
moving upper level trough to form over the west coast and east
pacific by late this weekend into early next week. Model output has
been consistent with showing lower to mid level thermal ridging
weakening over the forecast area while this trough develops, however
with a solidly strong position to start there'll still be remnants
of it to persisting causing the marine layer to persist Sunday into
Monday. At the same time much drier 925 mb rhs sweep in from the
northwest over the weekend probably mixing into the marine based
clouds with a tendency for lower level winds, and possibly surface
winds to go from onshore to having a weak southerly component. The
question is how will all of this influence the marine layer early
next week? It's just a guess that there could be an earlier than
usual clearing Monday morning.

For mid-late next week, a very deep low pressure area develops over
the gulf of alaska. The ecmwf, gfs, gem have been lean toward weak
long-wave troughing over the west coast. The southern extent of the
gulf of alaska low arrives as a trough bringing more pronounced
cooling and increasing onshore winds. Coastal drizzle is a possibility
in a deepening or even possibly a fully mixed out marine layer.

Aviation As of 10:22 am pdt Thursday for 18z tafs. Visible
satellite shows this morning's stratus continuing to mix out.

Expect the return toVFR conditions at all terminals within the
next hour. The building upper level ridge over the eastern pacific
will continue to compress the marine layer over the next 24
hours. This will likely lead to lower ceilings for Friday morning
at terminals impacted by stratus.

Vicinity of ksfo... Visible satellite shows this morning's stratus
quickly mixing out over the terminal as of the 18z TAF issuance.

Vfr conditions expected to prevail through at least the evening
hours. Light west winds will increase this afternoon to around 15
kt. Chance for stratus returns overnight, though the big question
is how the compressed marine layer will become.

Sfo bridge approach... Few lingering low clouds along the approach
possible until 1800 or 1830z, otherwise similar to ksfo.

Monterey bay terminals...VFR conditions expected to prevail
through this afternoon and early evening with the transition back
to ifr overnight. Can't rule out ceilings dropping to lifr levels.

Marine As of 08:43 am pdt Thursday... Generally light and
variable winds are expected over the coastal waters today. Locally
breezy conditions are possible later this afternoon and evening
near the golden gate gap and angel island. Expect increasing
northwest winds beginning late tomorrow and lasting through the
weekend as the ridge strengthens further.

Mtr watches warnings advisories
Tday Sca... Sf bay from 1 pm
public forecast: canepa as
aviation: rowe
marine: rowe
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Weather Map and Satellite Images
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Wind Forecast for San Francisco/Monterey Bay Area, CA (15,3,4,5)
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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 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 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.