Area Forecast Discussion
Issued by NWS Anchorage, AK

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000
FXAK68 PAFC 251338
AFDAFC

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
538 AM AKDT Sat Jun 25 2022

.ANALYSIS AND UPPER LEVELS...

An upper-level ridge extends from the Alaska Peninsula east
across the Southern and Eastern Mainland, keeping conditions
generally dry and clear for much of Southcentral. The exception is
the persistent layer of marine stratus that blankets the entire
Gulf of Alaska as a result of being under the ridge. The low cloud
layer has also spread along the Gulf Coast, including Prince
William Sound and around Kodiak Island. Overnight, the
southwesterly up-Inlet flow along the back side of the ridge
helped push the low stratus deck over a majority of Cook Inlet.

Out west, a large upper-level low is located over the central
Aleutians while an associated surface front pushes east across the
eastern Aleutians and Alaska Peninsula. As a result, these areas
continue to see rain and gusty southerly winds. For southwest
Alaska, cloud cover is gradually increasing from the west as the
front approaches the region. Areas of fog and/or smoke from
wildfires are spread across the Lower Kuskokwim Valley and
interior Bristol Bay this morning.

&&

.MODEL DISCUSSION...

Models remain in great agreement through the weekend and overall
forecast confidence is high. For the next few days, all models
depict an upper-level ridge amplifying over the Southern Mainland
while a trough digs in behind the ridge, over the Bering. The main
forecast uncertainty lies in the timing of the front approaching
southwest Alaska and how much rain it will produce. Models
generally agree that the front will stall over Southwest on Sunday
and Monday, eventually decaying over the region as it pushes into
the ridge.

&&

.AVIATION...
PANC...VFR ceilings and light westerly winds are expected to
continue through the TAF period. However, there is a chance that
low stratus over Cook Inlet could be advected into parts of
Anchorage as a result of persistent up-Inlet flow. MVFR
visibilities, due to smoke from wildfires, are expected through at
least this morning and could persist into the afternoon.

&&

.FIRE WEATHER...

Southcentral: While most areas will remain precipitation free the
next few days, it does look like temperatures and RHs will
moderate thanks to intrusion of the marine boundary layer. Areas
of low clouds will persist in Cook Inlet, across portions of the
Kenai Peninsula, and possibly make inroads into Anchorage and the
southern Mat-Su. Even if the clouds don`t move in, the persistent
onshore flow will provide for cooler temperatures and higher RHs.
Meanwhile, hot and dry conditions will persist inland, especially
across the Copper River Basin as the upper ridge moves overhead
Monday. While temperatures/RHs will reach Red Flag thresholds,
winds will remain light. Weak upper level short-waves will produce
some diurnal showers and thunderstorms in the Copper River Basin,
but it will be isolated to scattered in nature.

Southwest: South to southwesterly flow across southwestern Alaska
will continue for the next few days with high pressure near
southcentral and low pressure to the Bering. Winds will ramp up
this afternoon from east to west across the entire southwest.
Higher winds to about 35 kts are expected along the coast and the
Kuskokwim mountains. Further inland, widespread 15 to 20 kts
possible. Some downsloping is also possible on the lee of the
Kuskokwim mountains and while there will be a broad area of
precipitation possible along the coast, drier areas and gustier
winds in the downsloped areas will be possible within the swath of
southerly flow. Near the western Alaska Range, expect warmer and
drier weather with highs near 80s in the valleys and RHs getting
to around the mid 20s. The extent inland and the magnitude of
these gustier winds is less certain. There is however upper level
support and low level lapse rates to mix winds to the surface.
Given the potential, a Red Flag Warning is in effect today for
this afternoon and evening. Hot, dry, and windy conditions may
continue again for the western Alaska Range valleys Sunday
afternoon, but there is some uncertainty to whether it will be to
the extent expected today and how much moisture could advect into
the area going into the beginning of the week. Little concern for
lightning across southwest Alaska at this time.

&&

.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 through 3/Today
through Monday night)...

An upper level ridge will dominate the weather for the next few
days, leading to continued mostly dry conditions. The ridge will
slowly progress northeastward, becoming centered over the Copper
River Basin on Sunday, then along the ALCAN border on Monday. As a
result, the warmest temperatures will be over the Copper River
Basin, with highs of 80 or greater possible each of the next 3
days. Occasional mid to high clouds combined with a cool/stable
marine layer will result in notably cooler temperatures along the
coast, including along Cook Inlet. Areas of smoke will also serve
to block some of the solar radiation and keep temperatures a bit
cooler. Widespread low clouds will persist across the Gulf of
Alaska and Prince William Sound for the next couple days. The
surface high will build up Cook Inlet and the Susitna Valley
Sunday night/Monday, which should produce just enough offshore
flow along the eastern Kenai Peninsula to kick the low clouds
offshore and warm up temperatures. More uncertainty resides with
low clouds in Cook Inlet. Nighttime Microphysics satellite imagery
show widespread stratus developed overnight. With persistent up-
Inlet flow, this has potential to move into parts of Anchorage and
the Mat-Su. Have already trended downward on high temperatures
due to the presence of the marine airmass, but low clouds would
result in even cooler daytime temperatures.

Precipitation will be confined primarily to the Copper River
Basin. Weak short-wave transiting over top of the ridge today will
lead to isolated to scattered convection. Convection will likely
be limited to the northeastern Copper River Basin Sunday and
Monday as the upper ridge shifts eastward. The best chance for
showers and thunderstorms will be along the Wrangell Mountains and
portions of the Alaska Range. Meanwhile, a front moving in from
the Bering Sea will stall along the Alaska Peninsula west of
Kodiak Island. This could bring some very light rain to the south
end of the island Sunday-Monday.

&&

.SHORT TERM FORECAST SOUTHWEST ALASKA (Days 1 through 3: Today
through Monday)...

Upper southwesterly flow over southwestern Alaska will prevail
with a low over the Bering Sea and blocked high pressure over the
northern Gulf. Inland, near the western Alaska Range will be
warmer and drier through Monday, whereas areas along the coast
will be cooler in the 50s and 60s with rainfall expected today
through this weekend. This boundary along the coast has stalled
and will hardly move over the next few days with a few waves
expected to push additional rainfall to the coast. Storm totals
through Monday morning ranges from around a tenth in the Kuskokwim
Valley to about three tenths along the Kuskokwim coast and
between half inch near Dillingham to just shy of an inch closer to
Togiak and Cape Newenham. The highest amounts are due to upslope
on the southern faces of the Kuskokwim mountains. Some
precipitation will linger on the windward side of the mountains,
but overall should gradually decrease. South to southwest winds
will increase across the entire southwest today through Sunday
morning with the highest winds along the coast and Kuskokwim and
Aleutian Mountains. Winds will overall decrease Monday, but
breeziness will linger near the Kuskokwim Delta.

&&

.SHORT TERM FORECAST BERING SEA/ALEUTIANS (Days 1 through 3:
Today through Monday)...

Broad area of low pressure over Bering Sea this morning that will
remain through at least the short term and could remain parked
through the first half of the week. Expect mild temperatures
through the beginning of next week. Most of the Bering near the
Pribilofs east will have stronger winds. Some of the strongest
winds possible will be from the south, east of Unalaska through
the AKPen today up to around 40 kts with higher gusts to near 50
kts possible through bays and passes near Cold Bay. Rainfall is
expected through this windy swath with totals over the weekend to
around a quarter or a third of an inch. Near the AKPen on the
windward side, Sand Point could see as much as about an inch and a
half, King Cove about an inch. Details in the winds and
precipitation will depend on the shortwaves around the broader
low. Unsettled weather to the western Aleutians is expected to
begin Sunday afternoon as the low center dips further south and
then progresses towards the central Aleutians by Monday afternoon.
Not as strong of winds and QPF is expected with this wave.

&&

.MARINE (Days 3 through 5: Monday through Wednesday)...

Bering Sea/Aleutians: A low crosses the Aleutians into the
Southern Bering for Wednesday. Its front extends across the
Central Aleutians through Wednesday. Several troughs move over the
Bering by Wednesday. Forecast confidence is fair due to the
movement of the low. Southerly small craft winds and areas of
gales with the front move over the Aleutians and Alaska Peninsula
into the Bering, diminishing. Seas to 10 feet.

Gulf of Alaska: High pressure over the Gulf weakens through
Wednesday. Forecast confidence is good. Small craft winds along
the North Gulf Coast into Southeast Alaska, diminishing. Westerly
small craft winds blow through the Barren Island Tuesday and
Wednesday. Seas 10 feet or less.

&&

.Long Term Discussion (Days 4 through 7: Tuesday through
Friday)...

Looking ahead into the extended, upper level ridging continues to
influence Southcentral Alaska as the core of the ridge remains on
the ALCAN border. Shower and thunderstorm activity should remain
limited and mostly to the higher terrain of the Copper River Basin
and Alaska Range/Talkeetna Mountains for Tuesday. Heights
continue to fall during the rest of the period and models diverge
on exact timing and structure of synoptic features. However, it
appears that Southcentral will be under the influence of an upper
level trough during the latter half of the period for Thursday and
Friday. Cooler temperatures with shower chances, and occasional
thunderstorms in the favored upslope areas are possible with
passing upper shortwaves within the broader upper level trough.
Out west, there are hints of quieter weather with heights slow to
fall for the first half of the period before a shift in the
pattern occurs mid to late next week where guidance shows a series
of shortwaves impacting the region. The Middle Kuskokwim Valley
(including Sleetmute, Aniak, and Lime Village) and especially
interior Bristol Bay areas look to be the most unsettled with
convection mostly confined to the favored upper terrain.

An active storm track remains over the Bering Sea and Aleutians
and models generally agree on the broad upper pattern with a large
Aleutian low slowly migrating east with time. However, there
remains uncertainty with exact placement of this low over time
with some keeping it more confined to the western Bering while
others bring it into the eastern Bering. As a result, unsettled
weather with showery and gusty conditions are possible for the
Aleutians through the extended period.

&&
.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...Gale Warning: 165.
FIRE WEATHER...Red Flag Warning: 163.

&&

$$

SYNOPSIS AND MODEL DISCUSSION...AF
SOUTHCENTRAL ALASKA...SEB
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...VR
MARINE/LONG TERM...MV


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