Wednesday, April25, 2018

Marine Weather and Tides
Chignik, AK

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 6:04AMSunset 9:50PM Tuesday April 24, 2018 10:43 PM AKDT (06:43 UTC) Moonrise 1:22PMMoonset 3:45AM Illumination 75% Phase: Waxing Gibbous; Moon at 10 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 Chignik, AK
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location: 56.23, -158.35     debug

Area Discussion for -
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Fxak68 pafc 250336
southcentral and southwest alaska forecast discussion
national weather service anchorage ak
736 pm akdt Tue apr 24 2018

Analysis and upper levels
A moderate strength triple point low continues to slowly deepen
as it tracks northward up the west coast of alaska. A strong
upper level meridional jet streak and area of upper level
diffluence over southwest alaska this morning are sliding eastward
toward southcentral this afternoon, with a surface cold front
following closely behind. This storm system is producing
widespread strong winds along with localized heavy precipitation
in upslope areas.

Some of the strongest winds have been along turnagain arm (with
hurricane force wind gusts observed in portage valley and the
upper hillside of anchorage). Observed gusts to 45 mph (with
estimated gusts to 60 mph) were observed in the muldoon area and
along the S curves on the glenn highway. This has produced
widespread reports of downed trees, damaged fences and even some
severe damage to some homes along the anchorage hillside. These
winds have also brought widespread power outages to east
anchorage, hillside, and eagle river. Winds at lower elevations
have since diminished and become more squirrelly as the less side
trough strengthens. Down valley down inlet flow has kept the
turnagain arm jet centered out over the northern inlet, though
this will still bend into south to west anchorage as the surface
cold front arrives later this afternoon.

With strong low level south to southeasterly flow ahead of the
frontal system, south to east facing slopes are seeing the bulk of
the precipitation. Meanwhile, downslope flow on the opposite side
of the mountains is keeping some areas completely dry. Behind the
cold front, flow shifts to southwest and precipitation becomes
showery. The colder air is leading to a transition from rain to
snow across southwest alaska.

Back over the bering sea and aleutians, a large cyclonic circulation
with multiple embedded centers and short-waves is combining with
an unstable air mass to produce areas of rain and snow showers and
gusty winds.

Model discussion
Models remain in good agreement with large scale features
allowing for good forecast consistency and overall above average
confidence. Forecast challenges remain similar to the past couple
days: details of winds with strong frontal system moving across
the southcentral this afternoon through tonight along with
precipitation type as cooler low level air moves in. With
persistent gusty winds the boundary layer will remain well mixed
and surface temperatures will remain relatively warm (above
freezing) which would suggest rain or a rain-snow mixed, while
instability and heavier showers would produce all snow. Will
likely end up with a mix of everything across the forecast area. A
secondary challenge is timing of the many upper waves moving
through the upper level cyclonic flow which will act as the
primary forcing mechanism for showers.

Panc... While there likely will be fluctuations in windspeeds over
the next 24 to 36 hours as various features move through, there
is high confidence in persistent strong and gusty south to
southeast winds. The bigger challenge may be determining timing
of precipitation and impact on ceiling visibility. The best chance
for rain will be as the cold front moves through this afternoon,
which could even mix with snow at times. Suspect there will be
just enough low level downslope flow to maintainVFR conditions,
though could very briefly drop to MVFR or even ifr if snow does
develop. Behind the front beginning this evening, the mean flow
will become nearly due south which will make the terminal a bit
more susceptible to showers, so ceilings will likely hover in the
low endVFR category.

Short term forecast southcentral alaska (days 1 and 2)
A fall-like storm making its way through southcentral alaska
continues to bring strong winds and rain to much of the area, with
some snow at higher elevations and over the northern susitna
valley. Strong gusts will also persist across the lower
elevations of the anchorage bowl, as well as the palmer-wasilla
area and along the copper river through this evening, but should
remain below warning level. Gusty winds around the southcentral
area are expected to slowly diminish tonight through early
Thursday morning.

Rain and snow will begin to fill in over most of the previously
downsloped areas on the lee of the chugach mountains, as the front
passes through late this afternoon and winds become more
southerly. The bulk of precipitation is expected to remain along
the northern gulf coast and northern susitna valley through
tonight, becoming more showery by Wednesday morning. Specifically
north of talkeetna this evening through the overnight hours we are
expecting to see some snowfall accumulations as the colder air
moves in behind the front. Overnight snow accumulation for this
area is expected to be around 2 to 4 inches, but the southerly
flow aloft is a direction that could cause enhanced snowfall and
lead to higher amounts than currently expected. We are also
expecting snowfall through thompson pass tonight accompanied by
southerly winds, which is likely keep any blowing snow wet enough
to not reduce visibilities much. Some uncertainty remains due to
the potential for heavier precipitation to help drag down some
cooler air from aloft. This scenario could bring some increased
snow accumulation to the highway and start to interfere with

Short term forecast southwest alaska (days 1 and 2)
A wet and blustery pattern is anticipated the next two days. A
deep upper level low is rotating over the bering sea and will
continue to eject shortwave energy into the region. The radars at
bethel and king salmon have been very active and convective today.

Currently, the surface front is bisecting southwest and the
akpen and is progged to rapidly move eastward. The jet core
continues to push into southwest alaska and shift eastward
overnight. Strong winds expected in gaps, channels and other
areas with complex terrain. The vertical temperature profiles
continue to be complex and expecting to see a mix of rain and
snow. Tonight the first shortwave will become negatively tilted
enhancing the dynamics. In the wake of the frontal passage as
second shortwave will move into southwest bringing another round
of showers.

Short term forecast bering sea aleutians (days 1 and 2)
Cyclonic flow continues to dominate the bering. The surface front
has moved into the akpen. However, the upper level low is north
of the pribilofs. There are multiple shortwaves embedded in the
low. The latest ascat scatterometer pass has detected gale force
winds south of adak and unalaska, and also north of st matthew
island. Tomorrow the upper low will slowly drift to the north and
east allowing a shortwave ridge to momentarily build in over the
western bering aleutians resulting in a brief respite. By
Thursday, the next kamchatka low will have developed and will
begin to close in on attu island.

Long term forecast (days 3 through 7)
The long range forecast beginning Thursday night continues with
higher precipitation chances across the southern mainland as an
upper level bering low and associated surface front lifts north of
the bering strait through Saturday. The next storm system quickly
follows as a fast paced low tracks across the bering, making it
to the southwest coast by Saturday morning.

Models have been struggling with evolving the individual low
tracks as the jet stream acts as a 110+ conveyor belt which
remains along the aleutian chain and southern gulf through early
next week. Models are starting to align better with breaking the
ridge down over the gulf over the latter part of the weekend.

However, this is a new trend for the forecast at the start of next
week. Main updates for the extended forecast focus around stronger
winds along the bering and trends toward higher precipitation
chances for the southern mainland and surrounding waters.

Afc watches warnings advisories
Public... None.

Marine... Gale 119 125 155 165 170 172 173 174 176 180.

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

Weather Reporting Stations
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Airport Reports
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AirportDistAgeWind ktVisibilitySky/WeatherTempDewPtHumidityPressure
Chignik, Chignik Airport, AK6 mi1.8 hrsSE 17 G 2110.00 miOvercast44°F28°F53%1001.5 hPa

Wind History from AJC (wind in knots)
Last 24hr--SE16
1 day agoW12
2 days ago--NE13

Tide / Current Tables for Castle Bay, Northwest Arm, Alaska
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Castle Bay
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Wed -- 05:59 AM AKDT     2.86 feet Low Tide
Wed -- 06:09 AM AKDT     Moonset
Wed -- 07:01 AM AKDT     Sunrise
Wed -- 11:44 AM AKDT     7.51 feet High Tide
Wed -- 04:42 PM AKDT     Moonrise
Wed -- 06:29 PM AKDT     0.23 feet Low Tide
Wed -- 10:01 PM AKDT     Sunset
Tide / Current data from XTide NOT FOR NAVIGATION
Sorry tide depth graphs only, please select another station.

Tide / Current Tables for Chankliut Island, Alaska
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Chankliut Island
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Wed -- 05:55 AM AKDT     2.79 feet Low Tide
Wed -- 06:08 AM AKDT     Moonset
Wed -- 07:01 AM AKDT     Sunrise
Wed -- 11:44 AM AKDT     7.22 feet High Tide
Wed -- 04:41 PM AKDT     Moonrise
Wed -- 06:25 PM AKDT     0.23 feet Low Tide
Wed -- 10:00 PM AKDT     Sunset
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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GOES Local Image of Alaska    EDIT
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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