Marine Weather and Tides
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|Sunrise 5:58AM||Sunset 7:18PM||Thursday July 18, 2019 8:08 AM HST (18:08 UTC)||Moonrise 8:53PM||Moonset 6:36AM||Illumination 97%|
7 Day Forecast for Marine Location Near Adak, AKHourly EDIT Help
Area Discussion for -  (on/off)  Help NOTE: mouseover dotted underlined text for definition
|Fxak68 pafc 181202|
southcentral and southwest alaska forecast discussion
national weather service anchorage ak
402 am akdt Thu jul 18 2019
Analysis and upper levels
A large upper-level low continues to spin over the eastern gulf.
Behind it, an offshore flow dominates across southcentral with
a general uptick in temperatures and light northerly winds for
areas of the copper river basin and susitna valley. These outflow
winds continue to produce breezy west and northwesterly winds
through favored gaps and passes across portions of prince william
sound and the eastern kenai peninsula overnight. Gusty northwest
winds are also occurring across the barren islands south to
kodiak island and parts of the the coastal akpen due to the
pressure gradient between the departing low and a ridge over the
bering aleutians. Locations across the southcentral mainland
warmed into the upper 60s to mid 70s yesterday; however,
seabreezes kept coastal locations a touch cooler, with daytime
highs ranging from the upper 50s to mid 60s.
Showers and thunderstorms developed once again yesterday, mainly
over the higher terrain and across the bristol bay region due in
part to the added instability from northeast to southwest
propagating shortwaves rotating around the parent low. Much of
this activity has waned in the overnight hours with only a few
showers lingering around king salmon, iliamna, and over the
talkeetna mountains. Farther west, an onshore flow is keeping
a blanket of low stratus draped over the y-k delta.
For the bering sea and aleutians, things remain rather quiet as
high pressure remains the dominate weather feature. Satellite
imagery shows widespread low clouds and patchy fog across nearly
the entire region with a weak low spinning well south of adak.
Models remain in good agreement with evolution of large scale
features. The main forecast challenge continues to be the scale
of convective initiation and propagation as storm motion becomes
weaker and changes slightly over the course of subsequent
Panc...VFR conditions and light winds will persist. Light
southerly surface winds this morning will turn to the west-
northwest for the afternoon and evening hours. Showers and
thunderstorms are possible again today across the higher terrain
of the chugach mountains. Storm motion, however, looks to be much
much weaker today than previous days and will begin to turn
southerly by evening. Therefore, any convection that does develop
should remain over the mountains.
A southeasterly turnagain arm wind is expected to increase late
tonight through tomorrow morning. At this time, it does not appear
these winds will bend over the airport complex.
Weak offshore flow at lower levels will persist today. This will
result in generally warm and somewhat dry conditions. The
exception will be some diurnal wet thunderstorms over inland
areas. Storms will mainly stay in the higher terrain as the
steering flow is fairly weak. Conditions will be a little cooler
and humidities a little higher on Friday as weak onshore flow
develops. A few wet thunderstorms are still possible in the
afternoon for inland areas as the atmosphere remains somewhat
The southwest mainland will transition to a cooler, more humid
regime as onshore flow prevails. The main fire weather concern
today is potential for thunderstorms over the alaska range, as
the marine push won't propagate quite that far west. So, with
moderate instability expected won't be surprised to see some
single-cell thunderstorms pop up later today. With minimal
steering flow, anything that forms should stay anchored to
As for smoke, onshore flow should improve conditions in the
Short term forecast southcentral alaska (days 1 and 2)
The upper level pattern through Friday night is very weak. This
is because southcentral is very near a "col" in between high
pressure over the bering sea and the southwest yukon territory,
and a low pressure system over the gulf and a trough over northern|
Weak offshore flow at the lower levels will continue today. This
will allow temperatures at inland surface locations to warm into
the 70s to low 80s, with 70s possible even at coastal locations.
Some diurnal thunderstorms are possible today as the atmosphere
remains unstable. Most of the storms will be confined to the
mountains as the steering flow is very weak. On Friday the low
level flow becomes weakly onshore. Also, some moisture will begin
to push into the area from the east and increase the cloud cover.
These two factors will combine to lower high temperatures compared
to today. The atmosphere will become a little more stable, but
some thunderstorms are still possible over inland locations.
Short term forecast southwest alaska (days 1 and 2)
A ridge will continue building over the bering sea, and onshore
flow will moderate temperatures over the southwest mainland over
the next few days. Expect patchy fog and increased cloud cover
with the marine push... The challenge is gauging how far inland
fog will propagate. Fog low stratus is likely along the kuskokwim
delta and bristol bay coasts, but confidence drops farther inland.
In any case, afternoon highs will be cooler than what we've been
observing the last few days, and humidity will be higher.
The thunderstorm threat looks minimal in the short term, with the
only area of concern over the alaska range today. This area will
be east of the marine influence and under weak north flow, so may
see some garden-variety thunderstorms this evening. Anything that
forms should stay anchored to terrain.
The smoke forecast continues to be a challenge in the middle and
lower kuskokwim valley... Plenty of fires continue to burn in and
around these areas, but with the onshore push conditions should
Short term forecast bering sea aleutians (days 1 and 2)
High pressure over the bering sea will continue mostly benign
conditions over the next few days. Expect widespread fog and low
stratus, and probably some drizzle squeezing out as well. Winds
continue to be the focus for the forecast... Expect small craft
advisory level winds south of the aleutians and akpen as moderate
north winds channel through the gaps.
Marine (days 3 through 5; Friday evening through Sunday)
Generally light westerlies are expected across the bering this
weekend. Winds will likewise be light and variable over the
western aleutians near high pressure. Gusty northwesterlies are
likely west of unalaska, particularly in bays and passes, though
sustained gales are not expected. Waves should remain at or below
Light and variable winds and low seas are expected across the
Long term forecast (days 4 through 7; Saturday through Tuesday)
There is a noticeable difference in the long-range models from
yesterday. The strong ridge as indicated over southcentral the
past several runs now looks to be more suppressed, positively
tilted and slightly further west. This will impact the forecast in
that if the current solution verifies it will not be as warm.
Also, the position of the upper ridge will determine storm motion
with regards to any convection that develops along the mountains.
The general consensus at this time is not to buy in to the
present solution too quickly. Model agreement continues to degrade
thereafter with the GFS showing a much stronger upper low in the
gulf compared with the european model. Thus, overall confidence in
the long term forecast remains low.
Afc watches warnings advisories
Fire weather... None.
Synopsis and model discussion... Tm
southcentral alaska... Bl
southwest alaska bering sea aleutians... Mm
marine long term... Ap
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