Area Forecast Discussion
Issued by NWS Anchorage, AK
FXAK68 PAFC 241200
Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
400 AM AKDT Mon Apr 24 2017
.ANALYSIS AND UPPER LEVELS...
The general large scale upper level pattern consists of a broad
vertically stacked low over the central and eastern Aleutians and
a negatively tilted upper level ridge extending from the Southeast
Alaska Panhandle across the Yukon Territory and eastern mainland
Alaska. Moist southeasterly flow and a weak frontal system
extends from the western Gulf across the Kenai Peninsula and Cook
Inlet and into Southwest Alaska. Clouds and showers associate with
the big Aleutian low cover the Bering, Aleutians and Alaska
Models remain in good agreement with regards to the large low in
the Aleutians. Larger difference are evident in handling of the
surface low that tracks into the Southeastern Gulf around Tuesday
night. NAM was preferred for both domains.
PANC...VFR conditions will persist with light isolated showers
continuing off and on through the day. Southeasterly winds out of
Turnagain arm will wrap north into west Anchorage with breezy
conditions developing at PANC around 22Z and lasting through the
.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 and 2)...
Weak southeasterly flow aloft will continue through Tuesday.
A front over the northern Gulf will move onshore tonight. Most of
the precipitation with this front will fall along the coast and
coastal mountains. Isolated to scattered showers are expected for
inland areas. A weak ridge of high pressure will begin to nudge
into the area from the east Tuesday night, which will weaken the
flow aloft and dry the atmosphere out a bit.
.SHORT TERM FORECAST SOUTHWEST ALASKA (Days 1 and 2)...
A stagnant long-wave pattern will continue widespread clouds and
spotty rain showers across the mainland. The current upper low
pressure over the Bering Sea is centered between Adak and
Unalaska, which will keep the mainland in southeasterly flow at
nearly all levels. A weak upper-level jet and disturbances
propagating through the flow will send isolated to scattered
rain showers over much of the mainland, however many downslope-
prone areas will remain mostly dry. The pattern holds through
Wednesday with highs in the 50s and lows in the 30s. Winds will
remain generally light.
.SHORT TERM FORECAST BERING SEA/ALEUTIANS (Days 1 and 2)...
Broad easterly to northerly flow will remain over the Bering Sea
through the mid-week. Scattered rain showers will affect all of
the Bering Sea, while southern portions of the Alaska Peninsula
will see steadier rain. These conditions will remain pretty much
unchanged for the next few days.
.LONG TERM FORECAST (Days 3 through 7)...
The long range forecast continues with a drier pattern inland as
low pressure centers spin across waters of the Gulf and Bering.
However...at the end of next week the synoptic pattern slowly
shifts as the Bering low lifts northeast. Next Friday and
Saturday, the closed Bering low becomes an open wave over the
southwest with a trough axis swinging over Southcentral which will
bring increased chances for rain across the southern mainland.
The biggest challenge in the extended range surrounds the next
storm system for the western Bering as a low organizes in the
North Pacific. Model agreement is good with the initial timing of
the front, pushing into the western Aleutians late Thursday, but
they differ in the track and strength of the low as it progresses
east through Saturday. Overall, the main impacts of gale force
winds and rain are expected to remain over the Bering and
SYNOPSIS AND MODEL DISCUSSION...JER
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...ML