Thursday, September21, 2017

Marine Weather and Tides
False Pass, 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 7:42AMSunset 8:01PM Thursday September 21, 2017 1:12 PM AKDT (21:12 UTC) Moonrise 8:24AMMoonset 7:58PM Illumination 1% Phase: Waxing Crescent; Moon at 1 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 False Pass, AK
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location: 54.93, -164.47     debug

Area Discussion for -
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Fxak68 pafc 211254
southcentral and southwest alaska forecast discussion
national weather service anchorage ak
454 am akdt Thu sep 21 2017

Analysis and upper levels
The few hours of warm, sunny and clear weather as southcentral
passed underneath the axis of a transient upper level ridge are
coming to an end this morning. Kenai radar shows the next round of
rain spreading northward up the kenai peninsula into anchorage.

The upper level ridge over southcentral is getting quickly shunted
eastward by an invading upper level low near norton sound.

Precipitation is ending across the bristol bay region of
southwest alaska as well. The warm front associated with a slow-
moving broad low swirling south of the central aleutians extends
well east of the low, and that front is the primary source of lift
for the light rainfall. As the jet is set up in a southwest to
northeasterly flow over southwest alaska, the rain is not
progressing much into the kuskokwim delta region. The low south of
the aleutians is keeping light rainfall ongoing across much of
the chain as warm, moist air streams northward ahead of the low
and is lifted above the cooler air mass near the surface.

Model discussion
The models are in excellent agreement once again with the overall
broad scale pattern, a feat considering the plethora of ways the
pattern can evolve with the upper low moving south into southwest
alaska interacting with the low south of the aleutians, its
attendant warm front, and a rapidly changing jet stream pattern.

Thus, the model differences once again are limited to smaller
scale features. One such difference remains the timing of the
incoming precipitation. Thus far this morning, the radar
reflectivities with the incoming precip have been all bark and no
bite. In other words, despite indicating rain, a lot of it on the
leading edge of the precipitation shield is falling as virga.

During the day today, the NAM has been and continues to indicate
a bifurcation of the forcing across southcentral. Some of the
energy associated with the incoming upper low GOES north into the
susitna valley, while other energy associated with the advancing
warm front causes precipitation along the gulf coast. Being in
between, locations from kenai northeastward through anchorage and
the matanuska valley get relatively little, especially as
downsloping southeasterly winds kick in this afternoon. The other
models all tried to indicate the same in previous runs, but have
since backed off a bit. For consistency's sake, the NAM remains
the favorite in the short term. By Saturday however, it becomes
the outlier, racing the low and its associated energy northward
much faster than the other models, so it was eliminated as the
chosen model by that point. Confidence is high concerning the
broad pattern (cloudy and cool), but lower with smaller details
such as total precipitation amounts over the next several days.

Panc...VFR conditions and light winds will persist through the
early morning with off-and-on light rain. MVFR ceilings will be
possible for the rest of the day through into the overnight as the
next system moves through. The best chances of rain will be
through the morning with somewhat lesser chances during the late
afternoon and evening. Another round of somewhat heavier rain is
possible again Friday morning.

Short term forecast southcentral alaska (days 1 and 2)
Rain will overspread most of southcentral alaska early this morning
as a warm front approaches from the south. After an initial period
of steady rain, the rain will likely become intermittent for many
areas as the warm front is shunted eastward toward southeast
alaska. However, a strong southerly upper level jet will then
drive upper short-waves into southcentral along with a steady
supply of warm moist air from the sub-tropics. Deep south to
southwest flow will support periods of rain for most of the region
through Friday night. The heart of the copper river basin along
with kodiak city and vicinity will stay drier than surrounding
areas due to downslope flow. Meanwhile, upslope flow will bring
heavier rain to prince william sound and the susitna valley.

Flow will begin to shift to more of a southeasterly direction
beginning Friday night, as a trough approaches from the west.

This will lead to development of a downslope hole from the
western kenai peninsula to anchorage and portions of the mat-su.

This will also enhance rainfall totals over western prince william
sound. A flood watch is currently in effect for kenai lake and
kenai river from cooper landing to skilak lake due to an outburst
from the snow glacier dammed lake. The increased rainfall rates
Friday night into Saturday in the kenai lake-river system will
contribute to higher river levels. Will continue to monitor the
glacier lake release and forecast rainfall amounts to determine
the extent of flooding.

Short term forecast southwest alaska (days 1 and 2)
A wet pattern ensues through Saturday for much of the southwest as
a front pushes across the alaska peninsula and bristol bay this
morning then through the kuskokwim valley by the afternoon.

Isolated thunderstorms are possible today across the alaska
peninsula as an unstable environment moves in along the frontal
boundary which was evidenced early this morning south of the
eastern aleutians. The low associated with the front moves slowly
east through Saturday with the frontal boundary stalling across
the southwest during this time. The kuskokwim delta stays on the
drier side through Friday, then increasing chances for scattered
showers enters late Friday into Saturday as an upper level low
develops near the mouth of the yukon. Patchy fog is expected along
the frontal boundary as the cool saturated air mass is conditionally

Short term forecast bering sea aleutians (days 1 and 2)
A front moving into the aleutians this morning brings isolated
thunderstorm chances for the eastern islands and surrounding
marines through the morning hours. The associated surface low is a
slow mover as a ridge across the eastern pacific waters blocks its
progress. This results in the frontal boundary remaining
stationary through Friday morning, then a colder air mass pushes
through the aleutian chain in during that afternoon. A ridge
pattern slides north to south across the western waters through
Saturday. Patchy fog will develop across much of the bering the as
the stable ridge pattern traps moisture near the surface.

Long term forecast (days 3 through 7)
Beginning the extended period forecast Friday night, there will be
an arctic trough centered over eastern bristol bay with waves of
north pacific moisture rotating northward toward the gulf of
alaska. This pattern will support wet weather across the region
with the heaviest rain along the north gulf coast. Saturday night
into Sunday morning, a stronger front will move toward the coast,
but this feature now looks much weaker than it potentially was
looking the past few days. The main impact will be increasing
winds along the coast, along with more rain across southcentral.

By Monday and Tuesday, the upper low will begin to dig south into
the north pacific. This change will cut off the main moisture
supply and allow for gradual drying heading through the middle of
the week.

Afc watches warnings advisories
Public... Flood watch: 121 125
marine... Gales: 119 131 173 174 413 fire
weather... None.

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

Weather Reporting Stations
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Airport Reports
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AirportDistAgeWind ktVisibilitySky/WeatherTempDewPtHumidityPressure

Wind History from AKF (wind in knots)
Last 24hr------------------------------------------------
1 day ago------------------------------------------------
2 days ago------------------------------------------------

Tide / Current Tables for Cape Mordvinof, Unimak Island, Alaska
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Cape Mordvinof
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Thu -- 02:04 AM AKDT     1.29 feet Low Tide
Thu -- 08:25 AM AKDT     4.85 feet High Tide
Thu -- 08:42 AM AKDT     Sunrise
Thu -- 10:23 AM AKDT     Moonrise
Thu -- 02:19 PM AKDT     1.51 feet Low Tide
Thu -- 08:33 PM AKDT     4.89 feet High Tide
Thu -- 08:57 PM AKDT     Sunset
Thu -- 09:57 PM AKDT     Moonset
Tide / Current data from XTide NOT FOR NAVIGATION
Sorry tide depth graphs only, please select another station.

Tide / Current Tables for Cape Sarichef, Unimak Island, Alaska
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Cape Sarichef
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Thu -- 12:51 AM AKDT     1.52 feet Low Tide
Thu -- 07:35 AM AKDT     4.18 feet High Tide
Thu -- 08:44 AM AKDT     Sunrise
Thu -- 10:25 AM AKDT     Moonrise
Thu -- 01:03 PM AKDT     1.73 feet Low Tide
Thu -- 07:43 PM AKDT     4.23 feet High Tide
Thu -- 08:59 PM AKDT     Sunset
Thu -- 09:59 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 Alaska    EDIT

Ground Weather Radar Station Bethel, AK
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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.