Wednesday, September20, 2017

Marine Weather and Tides
Chenega, 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 7:40AMSunset 8:04PM Wednesday September 20, 2017 8:16 AM AKDT (16:16 UTC) Moonrise 7:00AMMoonset 7:30PM Illumination 0% Phase: New Moon; Moon at 29 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- 337 Am Akdt Wed Sep 20 2017
Today..W wind 15 kt. Gusts to 25 kt near whittier in the morning. Seas 2 ft.
Tonight..Variable wind less than 10 kt. Seas 1 ft.
Thu..E wind 10 kt increasing to 15 kt in the afternoon. Seas 2 ft. Rain.
Thu night..E wind 15 kt. Seas 2 ft.
Fri through Sun..E wind 10 kt. Seas 2 ft.

7 Day Forecast for Marine Location Near Chenega, AK
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location: 60.33, -148.15     debug

Area Discussion for -
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Fxak68 pafc 201242
southcentral and southwest alaska forecast discussion
national weather service anchorage ak
442 am akdt Wed sep 20 2017

Analysis and upper levels
The polar jet remains positioned over the area in a northwest to
southeast orientation from the northern bering across southwest
alaska and into the western gulf. A wave of energy moving along
the north side of the jet is currently spreading light rain across
the kuskokwim delta up through the lower kuskokwim valley.

Proximity to the jet appears to be hampering much southward
progress to the rainfall, however.

Another low centered south of the central aleutians consists of a
strong warm front transporting a subtropical air mass northward
across the eastern aleutians. The moisture-laden air mass is
producing rainfall that is heavy at times across much of the chain
this morning. This very warm air mass aloft is helping push the
jet north and east with time, which will play into the forecast
for mainland alaska over the next few days. More on that below.

Mainly clear skies and light winds across southcentral are
allowing temperatures to plummet across the region this morning,
with numerous locations dropping down into the 30s and threatening
a first frost for many inland locations.

Model discussion
The models all are in very good agreement for much of the short-
term. One significant difference appears by Thursday evening where
the GFS depicts a much stronger secondary low developing over the
northern gulf in advance of the subtropical air mass lifting
northward as compared with all of the other models. The other
models keep a trough over the north gulf coast, but it never
really develops. The result is the GFS shows much stronger winds
across the northern gulf than the other models, and being the
outlier, was eliminated as part of the forecast. The differences
between the other models were not significant with regards to that
feature. During the day Friday, the models diverge on
precipitation coverage, with the GFS and to a lesser extent the
nam ending the rain earlier in the day, with the other models
keeping more persistent rainfall. Forecast confidence remains
high with excellent overall model agreement, though confidence is
lower regarding those other differences between the models.

Panc...VFR conditions and light winds will persist. A brief shower
or sprinkle will be possible during the day, but should not cause
any long-term changes to theVFR conditions.

Short term forecast southcentral alaska (days 1 and 2)
A fast moving upper level short-wave trough over southwest alaska
this morning will cross southcentral today, bringing a quick shot
of rain to most inland areas, including the mat-su and copper
river basin. Areas to the south will remain dry with just some
passing mid to high clouds.

All eyes will then shift to the storm south of the aleutians,
which will send a warm front, with very warm and moist air toward
southcentral. There will be a break tonight between the departing
short-wave and this warm front, but mid to high clouds will
stream well out ahead of it. Thus, temperatures will not fall as
far as they did this morning for most of southcentral.

Rain will overspread kodiak island this evening then continue
north and east overnight through Thursday. It looks like a fairly
quick shot of steady rain for most places right out ahead of the
warm front. Development of a triple point low over the northern
gulf on Thursday afternoon combined with progressive flow in the
upper levels will then help shunt the deepest moisture eastward
toward southeast alaska. A persistent supply of upper waves
transiting southcentral combined with the fairly warm and moist
air mass in place will maintain a threat of rain Thursday night
and beyond. The forecast challenge will be to try and lock in on
specific features and associated rainfall.

Short term forecast southwest alaska (days 1 and 2)
There is a fast moving low and and associated frontal boundary
moving into western alaska. More precipitation is expected for the
kuskokwim delta. A break in activity is expected and then a
second wave of moisture will enter the region from the south and
move directly into the bristol bay coastline. Rain looks to
continue into Thursday evening and beyond as the longwave trough
extending from the arctic phases with the upper low south of the
aleutian chain and helps to establish broad southwest flow over
the region into the latter half of the week.

Short term forecast bering sea aleutians (days 1 and 2)
The latest ascat pass has the low south of adak. The associated
warm front is overtaking the aleutians. Expect rain and gale
force winds. These unsettled conditions will spread from the
central and eastern aleutians to the alaska peninsula and the
pribilof islands as the forecast period unfolds. The eastern half
of the bering will remain in a wet and windy pattern while
western portions of the bering including will remain on the drier
side on the back side of the longwave trough.

Long term forecast (days 3 through 7)
Beginning the extended period forecast Thursday night, there will
be an arctic trough merging with a north pacific warm front over
the state. Broad southwest flow will bring rain to most of
southern alaska heading into Saturday as the upper trough remains
in place. Uncertainty develops on Saturday night with another warm
front moving north toward the gulf of alaska with the ecmwf
favoring a deep 978 hpa surface low tucked into the west side of
the gulf. However, the 12z GFS and canadian gdps models are
notably weaker and much farther east with the surface low.

However, even with this uncertainty, there will still be plenty of
forcing for continued coastal rain and rain chances inland through
the weekend. Eventually, the upper low will move southward into
the north pacific and gulf of alaska, which, in theory, should
result in less precipitation chances heading into mid late week.

Afc watches warnings advisories
Public... None.

Marine... Gales: 170 173 175 177 178 179 411 412 413 414
fire weather... None.

Synopsis and model discussion... Jpw
southcentral alaska... Seb
southwest alaska bering sea aleutians... Ps
long term... Ja

Weather Reporting Stations
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Stations Dist Age Wind Air TempWater Temp WavesPressureDewPt
46081 - Western Prince William Sound 33 mi26 min NNE 5.8 G 7.8 51°F 50°F1018.4 hPa (+0.8)49°F
46076 - Cape Cleare AK 58 mi86 min WSW 5.8 G 5.8 53°F 53°F3 ft1018 hPa (+1.3)50°F
SWLA2 - 9455090- Seward, AK 69 mi46 min 54°F

Airport Reports
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AirportDistAgeWind ktVisibilitySky/WeatherTempDewPtHumidityPressure
Portage, Portage Glacier, AK48 mi23 minVar 310.00 miOvercast38°F37°F97%1019.6 hPa

Wind History from ATO (wind in knots)
Last 24hrW5W5W7W6
1 day agoE8
2 days agoCalmCalmE4CalmCalmCalmCalm3CalmCalmCalmCalmCalmCalmCalmS4S3CalmCalmCalmSE3S3CalmE7

Tide / Current Tables for Chenega Island, Dangerous Passage, Prince William Sound, Alaska
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Chenega Island
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Wed -- 01:57 AM AKDT     12.83 feet High Tide
Wed -- 07:33 AM AKDT     Sunrise
Wed -- 07:59 AM AKDT     Moonrise
Wed -- 08:06 AM AKDT     -0.99 feet Low Tide
Wed -- 02:24 PM AKDT     12.68 feet High Tide
Wed -- 07:56 PM AKDT     Sunset
Wed -- 08:27 PM AKDT     -0.36 feet Low Tide
Wed -- 08:29 PM AKDT     Moonset
Tide / Current data from XTide NOT FOR NAVIGATION
Sorry tide depth graphs only, please select another station.

Tide / Current Tables for Eshamy Bay, Knight Island Passage, Prince William Sound, Alaska
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Eshamy Bay
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Wed -- 01:59 AM AKDT     13.33 feet High Tide
Wed -- 07:32 AM AKDT     Sunrise
Wed -- 07:58 AM AKDT     Moonrise
Wed -- 08:04 AM AKDT     -0.99 feet Low Tide
Wed -- 02:26 PM AKDT     13.18 feet High Tide
Wed -- 07:56 PM AKDT     Sunset
Wed -- 08:25 PM AKDT     -0.36 feet Low Tide
Wed -- 08:29 PM AKDT     Moonset
Tide / Current data from XTide NOT FOR NAVIGATION
Sorry tide depth graphs only, please select another station.

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

GOES Local Image of PacificNorthwest    EDIT

Wind Forecast for (12,3,4,5)
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Ground Weather Radar Station Middleton Is., AK
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weather_mapweather_map weather_map

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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.