Tuesday, November21, 2017 L-36.com


Marine Weather and Tides
Anchorage, AK

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 9:22AMSunset 4:09PM Tuesday November 21, 2017 3:10 AM AKST (12:10 UTC) Moonrise 12:08PMMoonset 6:48PM Illumination 8% Phase: Waxing Crescent; Moon at 3 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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PKZ129 Passage Canal- 348 Pm Akst Mon Nov 20 2017
.small craft advisory Tuesday night...
Tonight..W wind 15 kt diminishing to 10 kt after midnight. Seas 2 ft. Freezing spray.
Tue..Variable wind less than 10 kt. Seas 2 ft.
Tue night..W wind 15 kt increasing to 25 kt after midnight. Seas 2 ft building to 4 ft after midnight. Freezing spray.
Wed..W wind 25 kt. Seas 4 ft.
Wed night..W wind 15 kt. Seas 2 ft.
Thu..E wind 15 kt. Seas 2 ft.
Fri..W wind 15 kt. Seas 2 ft.
Sat..W wind 10 kt. Seas 2 ft.

7 Day Forecast for Marine Location Near Anchorage , AK
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location: 61.18, -149.27     debug


Area Discussion for -
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Fxak68 pafc 210117
afdafc
southcentral and southwest alaska forecast discussion
national weather service anchorage ak
417 pm akst Mon nov 20 2017

Analysis and upper levels
A high amplitude ridge centered over the eastern bering sea is
building eastward toward mainland alaska. Subsidence with the
ridge combined with deep offshore flow is resulting in a bluebird
day across most of southwest and southcentral alaska. A deep and
mature vertically stacked low over the southern gulf is exiting
southward toward the northeast pacific, with snow falling on
kodiak island along the occluded front. Strong gap winds continue
on the back side of the low along the alaska peninsula, though
with the upper jet streak now exiting to the south and pressure
gradients beginning to slacken, winds are showing a diminishing
trend. More localized winds are being observed over southcentral
due to tight pressure gradients and a little bit of cold
advection. Aside from the typical coastal gap winds, the strongest
winds are being observed in the matanuska valley and valdez area.

This is due to the fact that deeper colder air naturally settles
into the copper river basin and these are two of the most
significant gaps under which it can escape.

Out to the west of the upper ridge, a short-wave trough and
surface low are tracking northward across the northwest bering
with a frontal system trailing to the south. This frontal system
is progressing eastward into the central bering and aleutians.

With a significant northward surge of warm air on the west side of
the ridge temperatures have warmed into the 40s to 50s along the
western to central aleutians and precipitation is falling as
rain.

Model discussion
Models are in excellent agreement with handling of major features
through Tuesday night and forecast confidence is high. Differences
do develop with track of a deepening low across the bering sea on
Wednesday and this will be discussed in the long term discussion
below.

Aviation
Panc... The only challenge for this TAF period is determining when
northerly winds will die down. Expect this to happen quickly as
the Sun sets and the upper ridge builds in, which should promote
decoupling of the boundary layer.

Short term forecast southcentral alaska (days 1 through 3)
Dry offshore flow continues across southcentral through Tuesday
afternoon. Gusty flow tapers off late tonight as the center of
the ridge shifts across the aleutian range to the kenai peninsula.

With skies clearing through this evening and winds slackening
overnight temperatures are expected to drop considerably early
Tuesday morning, approximately 10 degrees colder than this
morning's low temperatures. Steep temperature inversions just off
the surface may bring localized patchy fog along the cook inlet.

The next front moves quickly across Tuesday into early Wednesday.

The boundary moves across the aleutian and western alaska ranges
Tuesday morning with snow developing late Tuesday morning for
kodiak island. By late Tuesday afternoon or early evening the
front crosses over the susitna valley bringing snow to the kenai,
anchorage area and the matanuska valley. Only light amounts of
snow are expected with accumulations up to one inch. As this front
continues east across the copper river, prince william sound and
central gulf it rapidly diminishes as the upper level short wave
shears apart when running into the amplifying ridge along the
alcan border. Another transient ridge builds across southcentral
behind the front, however it is short lived as the next front
approaches late Thursday night.

Short term forecast southwest alaska (days 1 and 2)
A very progressive pattern will be on tap this forecast package. At
the onset of the forecast period, there will be weak ridging
extending from southwest ak to the akpen with a mature low
looming upstream. With a pool of cold air inland, the thermal
gradient will keep breezy winds over the akpen and in the
adjacent waters to the south this evening. As the aforementioned
low pushes into western alaska expect another round of
precipitation. Winds will be southerly ahead of the front which
will result in a tongue of warm air and a mixed mode of wintry
precipitation. In the wake of the frontal passage the snow level
will plummet to the surface and the light snow will spread
eastward through the day. Accumulations will range from 1-3
inches. The models ping into a fast moving re-enforcing shortwave
which will push across the area Wednesday morning bringing a quick
shot of showers. A more organized storm is anticipated later
Wednesday.

Short term forecast bering sea aleutians (days 1 and 2)
The pressure gradient between the low in the gulf of alaska and
the ridge over the akpen will result in gusty winds this evening
for portions of the akpen. A frontal boundary extending from
northeast russia to attu island will continue to move eastward
bringing unsettled conditions to the bering tonight and into
Tuesday morning. A second system will approach the region from
the north pacific and push northeast across shemya. This system
will continue to deepen as it treks toward the pribilof islands.

Expecting another round enhanced winds, rough seas and
precipitation from this storm.

Long term forecast (days 3 through 7)
The big storm of interest on day 3 starts in the western bering,
rapidly developing as it crosses the northern bering sea towards
the kuskokwim delta coast. As it approaches the coast, some warm
air will intrude with the southerly winds on the east side of the
low, but this system is not expected to be nearly as warm as the
last one and precipitation will likely remain all snow for the
west coast. Combined with strong winds ahead of the front, this
puts a risk for blowing snow reducing visibility along the west
coast through Wednesday afternoon. The other concern with this
storm is the effect of the storm force westerly and northwesterly
winds on the backside of the front, which will whip up high seas
as well. The low pressure system isn't expected to remain in the
area long enough to cause coastal flooding in the kuskokwim delta
and bristol bay, but areas north of dillingham that are prone to
erosion may see some impacts on Tuesday during the day. Behind the
low, strong northwesterly winds are expected to blast through the
pribilofs and hit the northern side of the ak pen Wednesday night
and Thursday. This may cause erosion problems and high winds
through gap areas for the ak pen as well.

So far, model consistency and agreement on the west coast storm
has been fairly good, although the latest version of the NAM pulls
the storm further inland. Since this solution seems to be an
outlier, the GFS ec solution was preferred for the storm track.

Once the low crosses the ak pen on Thursday, model solutions begin
to vary a bit more on where the low center will appear or reform
in the gulf of alaska. Regardless, it looks like it will stay far
enough south that the forecast challenge will be northerly gap
winds, including some stronger NE winds and higher seas for cook
inlet and along the north gulf coast.

In good news, behind this low pressure system, a ridge of high
pressure enters from the west, meaning that Thursday through
Saturday should be clear and cold for most of the state. The next
system to impact the alaska region is a low that is forecast to
move northward along the kamchatka peninsula, pushing a front
through the aleutians on Sunday. After the Sunday time frame,
model uncertainty becomes much higher, but for now, it looks like
a ridge will push storms approaching from the west away from the
mainland and into the gulf of ak.

Afc watches warnings advisories
Public... None.

Marine... Gale 127 130-132 150 173 175-178 180-185.

Synopsis and model discussion... Seb
southcentral alaska... Kh
southwest alaska bering sea aleutians... Ps
long term... Lf


Weather Reporting Stations
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Stations Dist Age Wind Air TempWater Temp WavesPressureDewPt
ANTA2 - 9455920 - Anchorage, AK 33 mi40 min E 1 G 1.9 15°F 31°F1012.5 hPa
46081 - Western Prince William Sound 60 mi20 min W 7.8 G 9.7 30°F 42°F1011.5 hPa (+0.7)23°F
SWLA2 - 9455090- Seward, AK 74 mi40 min 46°F

Wind History for Anchorage, AK
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Airport Reports
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AirportDistAgeWind ktVisibilitySky/WeatherTempDewPtHumidityPressure
Birchwood, Birchwood Airport, AK21 mi14 minESE 410.00 miFair4°F1°F88%1013.8 hPa

Wind History from ABV (wind in knots)
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Last 24hrSE4S4S5S5--S6SE4SE5S43NE12
G16
NE9
G16
S36SE6SE4------SE4SE3S5CalmSE3
1 day agoCalmSE4CalmNE8NE12NE11NE6NE3NE7NE5NE3N4N4CalmNE3NW4CalmCalmSW5S3CalmSE4S4S8
2 days ago--SE5SE5SE4SE3SE4S3SE3SE3S4S3S3S3SE5E5S3CalmCalmSE4CalmE4NE3CalmSW4

Tide / Current Tables for Anchorage, Knik Arm, Cook Inlet, Alaska
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Anchorage
Click for Map
Tue -- 03:02 AM AKST     0.53 feet Low Tide
Tue -- 08:48 AM AKST     29.20 feet High Tide
Tue -- 09:22 AM AKST     Sunrise
Tue -- 12:10 PM AKST     Moonrise
Tue -- 03:12 PM AKST     6.67 feet Low Tide
Tue -- 04:07 PM AKST     Sunset
Tue -- 06:50 PM AKST     Moonset
Tue -- 08:12 PM AKST     29.02 feet High Tide
Tide / Current data from XTide NOT FOR NAVIGATION
Sorry tide depth graphs only, please select another station.
12am1am2am3am4am5am6am7am8am9am10am11am12pm1pm2pm3pm4pm5pm6pm7pm8pm9pm10pm11pm
11.872.80.53.310.818.724.528.229.12722.917.712.99.16.88.314.922.627.32928.224.919.9

Tide / Current Tables for Anchorage (Knik Arm), Alaska
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Anchorage (Knik Arm)
Click for Map
Tue -- 02:45 AM AKST     -0.40 feet Low Tide
Tue -- 08:43 AM AKST     29.36 feet High Tide
Tue -- 09:22 AM AKST     Sunrise
Tue -- 12:10 PM AKST     Moonrise
Tue -- 03:06 PM AKST     6.40 feet Low Tide
Tue -- 04:07 PM AKST     Sunset
Tue -- 06:50 PM AKST     Moonset
Tue -- 08:29 PM AKST     29.55 feet High Tide
Tide / Current data from XTide NOT FOR NAVIGATION
Sorry tide depth graphs only, please select another station.
12am1am2am3am4am5am6am7am8am9am10am11am12pm1pm2pm3pm4pm5pm6pm7pm8pm9pm10pm11pm
11.95.50.8-0.339.717.824.628.629.327.323.518.513.18.56.481319.725.829.129.226.321.6

Weather Map and Satellite Images
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Weather Map
wmap_P
IR Satellite Image from GEOS
npac_satellite

GOES Local Image of Alaska    EDIT
Geos

Ground Weather Radar Station Kenai, AK
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weather_mapweather_map weather_map

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Disclaimer:
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.