Area Forecast Discussion
Issued by NWS Anchorage, AK

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000
FXAK68 PAFC 300115
AFDAFC

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
515 PM AKDT Wed Jun 29 2022

.ANALYSIS AND UPPER LEVELS...

Widely scattered thunderstorms have begun to form around the
Talkeetna Mountains and along the Wrangells. The storms are very
slowly tracking northward with time. Any areas that get caught in
the storms may be in for a couple hours of rain given the slow
movement of any one storm. Elsewhere, skies are mainly clear other
than some fair weather cumulus in Southcentral. That will change
later this afternoon and evening with potential for additional
storms along the Chugach and Kenai Mountains. Temperatures are
largely in the 70s and 80s except along the immediate coast.
Widespread smoke has enveloped much of Southcentral away from the
coast, and certainly persists over much of Southwest Alaska as
well. Some of the fires in Southwest Alaska are producing their
own pyrocumulus as evident on visible satellite. Air Quality
Advisories are in effect for a large swath of Southwest and
Southcentral.

Over Southwest Alaska, besides the smoke, a large fair weather
cumulus field has developed from interior Brisol Bay over to the
Kuskokwim Delta. Localized showers are possible from any of the
more well-developed cumulus but most areas should stay dry. After
some patchy dense fog in the King Salmon area this morning, things
have rapidly warmed area wide with most stations in the 60s and
70s across the Southwest this afternoon.

Finally out over the Bering, a large low is moving across the
western Bering, resulting in much cooler conditions and reductions
in visibility over the Pribilofs, with steady rain over the
Central Aleutians.

In the upper levels, weak diffuse ridging is in place over much of
the mainland. The weakening of this feature from previous days has
eroded the cap and is allowing more widespread shower and
thunderstorm activity. Meanwhile the swirling low over the western
Bering is vertically stacked with an upper level low. Any upper
level flow of note is closely confined to the Bering low, with
very little to no upper level flow over the mainland.

&&

.MODEL DISCUSSION...

The models are in decent agreement through Friday afternoon. The
main point of disagreement regards the evolution of a triple point
low/front south of the AKPEN on Friday. The foreign models are
keeping the disturbance as more of a front, while the American
models are developing a consolidated low earlier. Eventually by
Saturday all of the models develop a consolidated low southeast of
Kodiak. Nonetheless, how quickly this low develops will play a
direct role as to how far north the associated precipitation
shield can get, with earlier development resulting in rain that
stays further south away from the Kenai Peninsula. Regardless of
development, Kodiak will see a nice soaking rain from this low.
Otherwise, thunderstorm development and how far inland any marine
stratus can get will also be points of uncertainty. Overall
forecast confidence is high.

&&

.AVIATION...

PANC...VFR conditions and light winds will persist. Smoke will
limit visibilities occasionally to MVFR levels.

&&

.FIRE WEATHER...

Southcentral: Widely scattered thunderstorms will be most
widespread this afternoon and evening, gradually shifting back
north and east to along the Alaska Range and Wrangells by Friday
afternoon. Hot conditions in areas that stay mainly sunny are
expected each afternoon. Fortunately there are no real big wind-
makers expected today except for localized sea breezes. By
Thursday, an approaching front will increase southeasterly winds
through the gaps, which could fan any fires.

Southwest: Red Flag Warnings are in effect for Thursday afternoon
and evening for the Middle Kuskokwim Valley and Western Alaska
Range zones for hot, dry, and windy conditions. This will be
caused by an approaching front moving in from the Bering. While
the cloud cover and rain associated with the front will remain
offshore, during the day Thursday, the associated southeasterly
winds will really kick up through the gaps, especially the
Kamishak Gap across Lake Iliamna. With full sunshine expected, hot
and dry conditions will persist as the winds pick up. Rain moves
into Southwest Alaska on Friday. While it won`t impact the
Western Alaska Range and eastern Kuskokwim Valley unfortunately,
it will bring much cooler and cloudier conditions on Friday to
those fire-weary areas, despite the winds taking a bit longer to
subside.

&&

.SHORT TERM FORECAST SOUTHCENTRAL ALASKA (Days 1 through 3: Tonight
through Saturday)...

Upper-level ridging will continue to dominate over Southcentral
Alaska tonight and Thursday. Under the influence of the ridge,
skies will remain mostly clear across the region with the
exception of convective activity developing primarily along the
mountain ranges. This evening, isolated to widely scattered
thunderstorms are active from the Talkeetna Mountains eastward
into the Copper River Basin. Thus far, only limited cumulus growth
has occurred further west over the Kenai Mountains and Chugach
Mountains east of Anchorage. Very isolated thunderstorm activity
may still develop in these regions this evening, with the most
favored location likely to be the far northern Kenai Mountains.
However, over the Chugach Mountains near Palmer, cumulus
development appears stunted and has even begun to dissipate this
afternoon. Region-wide, areas of the strongest and most abundant
thunderstorms are expected to hug the mountains where conditions
are most favorable for initiation, keeping lower elevations, with
the exception of the Copper Basin, dry.

Smoke will be another impediment to truly clear skies, with
widespread smoke and haze from wildfires in Southwest and Interior
Alaska present across the region. A weak trough tracking into the
western Gulf of Alaska will cause a shift to weak onshore flow
tonight, which should begin to clear out the bulk of the smoke
from south to north through Thursday. The onshore flow will also
contribute to cooler temperatures and a slight increase in
moisture on Thursday as well. This will also contribute to a more
stable atmosphere closer to the coast, meaning thunderstorm
activity will be more limited to the Talkeetna Mountains and
Copper Basin tomorrow afternoon and evening.

Thursday night, a strong shortwave trough and accompanying front
enters the area from the Bering Sea, reaching Kodiak Island Friday
morning, with the island seeing rain as the front passes. As the
shortwave impinges on Southcentral, onshore flow allows temperatures
to continue to cool, and moisture continue to increase. However,
the development of a triple-point low in the far western Gulf on
Friday will lead to the front wrapping up around the low and
parceling off the much needed precipitation and sending it
eastward across the Gulf. It is increasingly likely that the front
will avoid all but the southern tip of the Kenai Peninsula,
keeping Southcentral dry into the weekend. Cloud cover and
onshore flow will at least bring cooler conditions to the region,
and keep convection on Friday and Saturday limited to the Alaska
Range.

&&

.SHORT TERM FORECAST SOUTHWEST ALASKA (Days 1 through 3: Tonight
through Saturday)...

High Pressure over much the region is continuing to bring a
warming and drying trend along with weak overall flow. Daytime
heating, along with convective potential near the Western Alaska
Range, will allow for some marginally unstable air to develop
this evening resulting in possible isolated wet thunderstorms,
mainly near the Alaska Mountain Range. However, any popcorn
showers that manage to develop into a thunderstorm should be
fairly isolated, slow moving, and would dissipate through the
night. A front associated with a low located in the Bering Sea
will approach the Southwest coast Thursday. This will result in
gusty southeasterly winds, especially along the coast, through
Kamishak Gap, and along the windward side of the Kuskokwim
Mountains. Gusty winds will continue through overnight Thursday
through at least Friday night. Expect gusty downsloping winds
along the Alaska Range, higher temperatures, and low relative
humidity values. As a result, a Red Flag Warning has been issued
for Thursday afternoon until 1AM AKDT Friday for the Alaska Range
and eastern portion of the Middle Kuskokwim Valley zones. Cloud
cover will increase Thursday night along the coast and spread
inland with widespread rain showers expected by Friday afternoon.
A vertically stacked surface low will move south of the Alaska
Peninsula near Kodiak Island Saturday and will give way to more
precipitation the Greater Bristol Bay and spread into the
Kuskokwim Mountains.

&&

.SHORT TERM FORECAST BERING SEA/ALEUTIANS (Days 1 through 3: Tonight
through Saturday)...

An upper-level low is located in the western Bering with its
associated front bringing small craft southerly winds and moisture
into the central Aleutians. The aforementioned front will slowly
progress eastward towards the Mainland coast in the coming days,
bringing with it small high end small craft southerly winds and
precipitation. Higher winds will be concentrated near the
Southwestern coastline and Bristol Bay Friday morning. A ridge
will build in behind this front, but will have a brief impact as
another front develops over the western Aleutians Friday
afternoon. By Saturday morning, a majority of the western Bering
will have south to southwesterly flow as another feature begins
to impact the region.

&&

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

Bering Sea/Aleutians: A low complex over the Western Bering
merges to form a single low for Monday. Its front extends across
the Central Bering and Aleutians by Monday. Forecast confidence is
fair with the front`s movement. Southwest winds less than gale
force spread across the Central Aleutians and Bering through
Monday, diminishing. Seas to 10 feet, subsiding.

Gulf of Alaska: A front enters the Western Gulf Saturday and
extends across the Gulf through Monday.Its low exits the Southern
Gulf late Sunday. Forecast confidence is good. Southeasterly
small craft winds spread over the Western Gulf through Kamishak
Bay, with areas of gales through Shelikof Strait for Saturday,
diminishing. Seas 10 feet in Shelikof Strait Saturday, less than
10 feet elsewhere subsiding through Monday.

&&

.Long Term Discussion (Days 4 through 7: Sunday through
Wednesday)...

Unsettled conditions are forecast across Southwest over the
weekend while an upper low anchored over the Western Bering sends
multiple disturbances across the Bering and into Southwest through
the middle of the week. This will see increased cloudiness and
scattered showers along with cooler temperatures on Sunday. Higher
pressures briefly move into Southwest on Monday, which will help
to end precipitation chances for the region and allow for warmer
temperatures. However, models hint at a continued active pattern
into next week with one or two additional shortwave disturbances
to lift across the region through Wednesday. This should gradually
break down high pressure over Southwest and put precipitation
chances as well as cooler temperatures back in the forecast.
Meanwhile, a different story is anticipated across Southcentral. A
trough over the Gulf of Alaska will become closed off on Sunday
while shifting southward into the North Pacific Monday through
Wednesday. This will allow for the upper level ridge over the
Copper River Basin to re-strengthen and ridge westward back into
much of Southcentral. Thus, dry conditions and a warming trend are
forecast Monday into Wednesday.

&&
.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...Gale Warning: 170.
FIRE WEATHER...Red Flag Warning 153 163.

&&

$$

SYNOPSIS AND MODEL DISCUSSION...JW
SOUTHCENTRAL ALASKA...CQ
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...NS
MARINE/LONG TERM...KZ/BL


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