Area Forecast Discussion
Issued by NWS Anchorage, AK

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000
FXAK68 PAFC 190051
AFDAFC

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
451 PM AKDT Mon Jun 18 2018

.ANALYSIS AND UPPER LEVELS...
The strong surface low that has been tracking toward the area out
of the North Pacific is now in the Bristol Bay region with the
front stretching over the Kuskokwim Valley to the Susitna Valley
and then Copper River Basin. This front has brought strong winds
and heavy rain to the Gulf coast since last night.

The upper level low is situated near the Pribilof Islands this
afternoon and extends over most of the Bering Sea and mainland
Alaska. There is also an upper level ridge over southeast Alaska
with the jet stream running south-to-north over the central Gulf
of Alaska, eastern Prince William Sound and through the Copper
River Basin. This jet has enhanced the rainfall over the north
Gulf coast and its movement to the east will help the remaining
rainfall to be lighter than it was earlier in the day and last
night.

&&

.MODEL DISCUSSION...
In the big picture, the models are in good synoptic agreement and
agree on moving the main surface low into the eastern Bering Sea
and keeping it there, slowly weakening, until the end of the week.

&&

.AVIATION...
PANC...VFR conditions should persist though there is a chance for
brief MVFR ceilings this evening to overnight. Southeast winds
will persist overnight but should be diminishing as the night
wears on.

&&

.SHORT TERM FORECAST SOUTHCENTRAL ALASKA...
The synoptic pattern of an upper level low over the eastern
Bering and ridging east of Southcentral Alaska will continue into
Thursday. The system that pushed through the area Sunday night and
brought heavy rain and strong winds to Southcentral Alaska has now
pushed off to the north leaving southerly flow aloft over the
area. With the exit of this system both rain and winds will
diminish somewhat through the night but light showers and winds
will remain through Wednesday for much of Southcentral Alaska.
Late Tuesday, another front will move through the pattern
bringing more rain to the southern Kenai Peninsula and Prince
William Sound by Wednesday.

&&

.SHORT TERM FORECAST SOUTHWEST ALASKA (Days 1 and 2)...
The mainland is getting into a steady state pattern, anchored by a
stacked low pressure system setting up in the eastern Bering Sea.
The front associated with the system is currently working over the
mainland and will continue across the Kuskokwim Delta this
evening. The next two days will then be characterized by a weakly
unstable cyclonic flow. Expect scattered rain showers over most
areas, with some lee-side drying to the west of higher terrain.
Mostly cloudy conditions and below normal temperatures will
persist with generally light southeast winds. On Tuesday, there`s
an outside chance at some thunder as a disturbance and pocket of
cold air aloft passes overhead, but confidence was not high enough
to include it in the forecast.

&&

.SHORT TERM FORECAST BERING SEA/ALEUTIANS (Days 1 and 2)...
Generally light to moderate northwesterly flow will persist for
the next two days. A front will rotate toward the Pribilof Islands
this evening and slowly decay and linger, bringing rain to the
area. High pressure over the western Bering will promote fog and
low stratus, especially during the overnight hours.

&&

.LONG TERM FORECAST (Days 3 through 7)...

The long term forecast beings Thursday evening with the dominant
upper-level features being a broad, closed low over the eastern
Bering and a ridge downstream extending through the Yukon into
east-central Alaska. At the surface, this translates to a
weakening low remaining rather stationary over the eastern Bering
and a ridge over the Gulf of Alaska. A trough is situated just
south of the Brooks range, extending into the Yukon.

The broad low in the Bering and high downstream will result in a
predominant southwesterly flow through much of the vertical
profile, keeping clouds and showers over southern Alaska through
Friday. By late Friday though the weekend, a surface ridge builds
over southern Alaska as the low in the Bering fills in and
retreats to the west. This will result in a gradual warming trend
across the forecast area as an offshore flow develops. However,
lingering moisture, daytime heating, and added instability from a
shortwave trough traversing from the AKpen into central Alaska
will still support widespread shower activity (diminishing in
areal coverage each day) through the end of the weekend.

Models diverge with the timing, intensity, and track of a low
across the Aleutians for the weekend. Nonetheless, expect the
broad trough over the Aleutians to remain through the weekend
with clouds and rain moving across the Aleutians as the weekend
progresses, reaching the Alaska Peninsula for Monday.

&&


.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...Flood advisory 125.
MARINE...None.

&&

$$

SYNOPSIS AND MODEL DISCUSSION...EZ
SOUTHCENTRAL ALASKA...DK
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...ML
LONG TERM...TM


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