Area Forecast Discussion
Issued by NWS Anchorage, AK

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000
FXAK68 PAFC 251313
AFDAFC

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
513 AM AKDT Mon Mar 25 2019

.ANALYSIS AND UPPER LEVELS...

The upper levels feature a largely zonal (west to east) upper
level wind flow across most of mainland southern Alaska. A ridge
rapidly building northeastward over Kodiak Island this morning
will become the dominant upper level feature over Southcentral the
next few days. Out west, a large storm over the western Bering has
become vertically stacked. Thus, the center of the surface low
is also the center of a strong upper level low and associated
trough. The storm produced its strongest gust in Adak around 11pm
last night, reaching 89 mph. The winds across the Central
Aleutians are now trending downward. The upper level trough
contains more seasonably cold air underneath it, which is sweeping
eastward across the Bering. The cold front and leading edge of
that cold air is approaching the Pribilof Islands and Dutch
Harbor. Associated rain is moving in across the Kuskokwim Delta
this morning, but radar shows any substantive rain staying west of
Bethel for now. Further east across mainland Alaska, some high
and mid-level cloud cover continues to stream across the area.
Otherwise, quiet weather continues as the gap winds through
Turnagain Arm wane. Meanwhile, unseasonably warm weather
continues for most of the area with numerous locations seeing low
temperatures around where the average high is for this time of
year.

&&

.MODEL DISCUSSION...

The models are in excellent agreement through the next 48 hours,
and thus, forecast confidence is high. Relatively quiet weather
for most of the area contributes to the high confidence forecast
as well. The biggest challenge will be potential fog development
over the next few days as a strong ridge and more warm air moves
in, supporting a capping inversion, with snowmelt contributing to
low-level moisture.

&&

.AVIATION...
PANC...The Turnagain Arm wind will diminish over the next few
hours as it weakens and drifts south of the airport. After that, VFR
conditions and light winds will persist for the rest of the day.
Tonight, fog development cannot be ruled out, and has been added
to the TAF. It will be a recurrent problem for the next several
nights.

&&

.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 and 2)...
High pressure will build over the area today. Dry conditions are
expected over the Southcentral mainland and northern Gulf for the
next few days after some lingering showers around Prince William
Sound and the northern Susitna valley end by this afternoon.
Offshore winds will increase tonight through gaps in the terrain
as a surface "lee low" forms in the northeastern Gulf due to the
northerly flow aloft. These winds will decrease on Tuesday as the
upper ridge slides eastward. For inland areas winds will be
fairly light, and there could be some patchy late night and
morning fog for some areas. The cloud cover forecast becomes a bit
difficult with the ridge axis sliding eastward, allowing some high
or even mid level clouds into the area.

&&

.SHORT TERM FORECAST SOUTHWEST ALASKA (Days 1 and 2)... (Today
through Tuesday evening)

Above average temperatures will continue today associated with
strong warm air advection ahead of an occluding front originating
from 30N. Downsloped areas could see highs today approaching 50.
Light rain is currently occurring across the Kuskokwim Delta and
will gradually diminish today as the front weakens over interior
regions. Scattered showers are possible through Tuesday over
the southwest mainland, with more seasonal temperatures likely as
the southerly flow weakens ahead of a ridge.

.SHORT TERM FORECAST BERING SEA/ALEUTIANS (Days 1 and 2)...
(Today through Tuesday evening)

A strong ~950mb low is currently centered over the western Bering
and is bringing storm force winds and hurricane gusts to the
western Aleutians this morning. Winds are expected to diminish to
gales by this afternoon, however storm force winds will continue
through this evening over the central Bering as the low will
continue to slightly strengthen aided by divergence in the left
exit region of a strong upper jet. Given this fast upper level
flow, the entire system will quickly depart to the north with sub
gales and lower seas expected Tuesday.

&&

.MARINE (Days 3 through 5)...

Gulf of Alaska... Expect generally benign conditions, with winds
diminishing and seas subsiding as pressure builds.

Bering Sea...Gale force winds will diminish through Wednesday with
high pressure building across the eastern Bering Thursday.
Confidence is increasing with periods of southerly gale force
winds over the Bering Sea and Aleutians Thursday through Saturday.

&&

.LONG TERM FORECAST (Days 4 through 7)...

Southcentral: High pressure will be entrenched across the
mainland through the end of the week. Confidence that a shortwave
will traverse the Bering Strait Friday and work to flatten the
ridge is increasing. Weak southerly flow will help to promote some
showers along the Alaska Range and clouds locally. Much of
Southcentral will remain dry with temperatures remaining in the
mid/upper 40s and overnight lows flirting with freezing, keeping
the trend of well above normal temperatures well into the weekend
and beyond.

Southwest/Bering: High Pressure will dominate the weather pattern
through the end of the week. The aforementioned shortwave sliding
across Alaska will bring a mix of rain and snow to the King
Salmon/Dillingham to Rainy Pass corridor and along the Kuskokwim
mountains. A series of fronts will bring active weather across the
western and central Aleutians mid week and again leading into the
weekend.


&&


.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...High Wind Warning 187.
MARINE...Hurricane Force 413.
 Storm Force 411 412.
 Gales 414.
FIRE WEATHER...NONE.

&&

$$

SYNOPSIS AND MODEL DISCUSSION...JPW
SOUTHCENTRAL ALASKA...BL
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...KVP/AP
MARINE/LONG TERM...SS


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