National Weather Service United States Department of Commerce


000
FXAK68 PAFC 271331
AFDAFC

Southcentral and Southwest Alaska Forecast Discussion
National Weather Service Anchorage AK
531 AM AKDT Mon Jun 27 2022

.ANALYSIS AND UPPER LEVELS...

A large area of high pressure persists across Southcentral and
the Gulf of Alaska as an upper-level ridge extends from the region
east across the Eastern Mainland. The interior areas of
Southcentral are seeing generally clear skies this morning which
will persist through the day as a result of the ridge. Widespread
marine stratus continues to cover most of the Gulf but is less
extensive across Cook Inlet and Prince William sound compared to
the past few mornings. During the overnight hours, low clouds
developed over the western Kenai Peninsula again and then extended
north into the Anchorage and Birchwood areas. The stratus is
expected to break up by early afternoon today.

Upstream of the ridge, an upper trough is exiting to the
northeast over southwest Alaska as an associated surface front
pushes into the ridge and decays over the region. This is
maintaining cloud cover for Southwest as well as some much needed
rainfall across the Lower Kuskokwim Valley, interior Bristol Bay
locations, and near the Kuskokwim Mountains. Farther west, a large
upper-level low is located over the western Bering while a
surface front pushes across the Central Aleutians. Thus, overcast
skies, areas of fog, and rain with the front are dominating the
far western domain this morning.

&&

.MODEL DISCUSSION...

Models are in good synoptic agreement for the next few days, so
forecast confidence is high. All models depict a low spinning over
the western Bering while its front progresses east across the
Central and Eastern Aleutians through Wednesday morning. However,
there are some differences regarding an upper-level disturbance
that develops over southwest Alaska on Tuesday afternoon.
Depending on how this disturbance evolves could have an impact on
thunderstorm potential and coverage along the Alaska Range that
day.

&&

.AVIATION...
PANC...VFR conditions and light westerly winds will persist
through the TAF period. Areas of marine stratus may drop ceilings
to MVFR or IFR at times, but any lingering stratus is expected to
break up by early afternoon today.

&&

.FIRE WEATHER...

Southcentral: Fire weather conditions will deteriorate as we head
through the week, with a return to widespread hot and dry
conditions. Also, generally expect an increase in thunderstorm
activity as we head through the week. The key forecast problem is
the areal extent of thunderstorms and resultant lighting activity
level (LAL), which will help determine whether Red Flag Warnings
should be issued. At this point in time, the forecast is calling
for isolated to widely scattered thunderstorms with LALs no higher
than 3. This is based on increasing airmass instability, focused
along the thermal trough. At this point in time, there does not
seem to be any other forcing mechanisms (such as a short-wave
trough). While that is not absolutely necessary to reach an LAL of
4 or higher, it means you need greater instability to produce
more thunderstorms and lightning. Model guidance does vary in some
key stability parameters, but has generally been trending toward
more unstable conditions. The area of most concern for a lot of
lightning is the northeastern Copper River Basin (Tok Cutoff
corridor) on Tuesday, then nearly all of the Copper River Basin on
Wednesday.

Southwest: Rainfall becomes more showery and will continue to
diminish throughout the day today. Residual moisture will linger
where upslope terrain enhancement can occur. Temperatures will
trend a little warmer for Southwest as some of the skies begin to
clear. High resolution models hint at slight convective potential
this afternoon. Any daytime surface heating and residual upper
level forcing would allow for pop up showers to potentially
produce a few lightning strikes near Lime Village east towards the
Western Alaska Range. Wednesday is another potential day for
isolated thunderstorms, but the convective forecast continues to
be tricky with regards to the strength of instability and
available forcing for convective initiation, especially for
Tuesday afternoon near the Western Alaska Range.

&&

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

The marine layer stratus deck is much less extensive in Cook
Inlet and Prince William Sound then it was over the weekend. As a
result, expect the areas of low clouds that do exist to clear out
more quickly today, leading to marginally warmer temperatures
along and near the coast. Hot and dry conditions will persist
inland, especially across the Copper River Basin. The thermal
trough, which has been centered over the Yukon, will shift
westward toward the eastern Copper River Basin today, with an
uptick in diurnal thunderstorms expected from the north side of
the Wrangell Mountains up to the Alaska Range.

The big story as we head through Tuesday and Wednesday will be a
return to hot and dry conditions across Southcentral along with
increasing thunderstorm activity each day. The thermal trough will
shift westward across the Copper River Basin to the Talkeetna
Mountains Tuesday, then encompass nearly all of Southcentral by
Wednesday. Weak offshore flow will develop tonight through Tuesday
in response to a building surface ridge from Southwest Alaska
into the Interior. This will contribute to warming temperatures
and further destabilization of the atmosphere along with locally
gusty winds along the coast (namely Seward and Whittier). The best
chance of thunderstorms will remain over interior Southcentral
Tuesday, but it looks good for isolated thunderstorms farther
south on Wednesday. However, based on the flow (which will be
weak), any storms which do form will likely be focused along the
Kenai and Chugach Mountains. This mean little or no rainfall for
the very dry areas of the western Kenai Peninsula, Anchorage, and
southern Mat-Su.

&&

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

Cloudy skies are expected today with rain showers gradually
decreasing throughout the day and become more isolated tonight and
Tuesday as the upper trough lifts north. Enough daytime surface
heating along with residual upper level forcing lingering near the
Western Alaska Range this afternoon and evening may be enough for
isolated thunderstorms to form from around Lime Village eastward.

A shortwave ridge builds over Southwest Tuesday afternoon to help
clear some of the clouds inland and warm temperatures slightly.
There is uncertainty in the stability and forcing for the
potential for thunderstorms. A drier and warmer weather trend will
continue Wednesday. The convective potential for thunderstorms
increases on Wednesday and with skies being a little more clear,
the surface will warm more efficiently and aid with instability.
For Thursday, southerly flow will return to the coast and
temperatures will begin to cool again as a front approaches
Southwest.

&&

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

A low over the western Bering Sea remains stalled over the area
for the next few days. Its front stretches west of the Pribilofs
to near Adak and into the North Pacific. The orientation of this
front will allow rainfall and southerly winds approaching gale
force to sweep across the Aleutians today through Tuesday. The
front is not expected to cross the Pribilofs until late Tuesday
and at which point starts to weaken as rain shower potential and
decreasing winds continues eastward into the eastern Bering.
Wednesday afternoon, another broad swath of rain and wind lifts
northward near Atka and reaches the Pribilofs after midnight
Wednesday into Thursday before progressing eastward Thursday
night. Temperatures stay moderated in the 40s and 50s.

&&

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

Bering Sea/Aleutians: Wednesday night, a weak triple point low
develops over the central Aleutians and tracks into the Bering
Sea, pushing a front from the central Aleutians to the Alaska
Peninsula through Friday. Confidence remains moderate that gale
force winds will develop and persist along this front. Localized
gale force gap winds, however, will be likely from Atka eastward
into Bristol Bay Wednesday through Friday. Seas are not expected
to exceed 20 feet.

Gulf of Alaska: With high pressure remaining in place over the
Gulf, winds less than gale force and seas less than 20 feet are
expected for the days 3 through 5 period.

&&

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

Looking ahead into the extended forecast, the latest operational
model runs are in good agreement with the evolution and
progression of the synoptic scale features, but diverge in the
specific details towards the end of the period. A strong ridge of
high pressure seems to be a key dominant player influencing
Mainland Alaska with temperatures expected to be above normal and
precipitation below normal across Southcentral. With the exception
of the higher terrains and favored upslope areas, the potential
for any diurnally driven convection associated with weak
shortwaves seems to be low given the subsidence aloft and weak
instability. By midweek, the ridge axis slowly shifts east and
stalls in the eastern mainland and parts of the Panhandle in
response to a deepening trough and embedded upper low in the
Bering Sea. Most of the ensemble runs are taking the Bering upper
low a more northerly track rather than northeasterly between
Thursday to Friday. Another upper low forms at the base of the
trough and moves from the North Pacific into the Gulf Alaska late
next week. Meanwhile, the approaching trough and a surface low
will lead to increasing moisture and rainfall chances first for
the Aleutian Islands and then spreading into Southwest Alaska
along and ahead of the attendant front. The aforementioned ridge
may begin to break down across much of the mainland over the
weekend but confidence is low if any precipitation makes its way
over the region.

&&
.AFC WATCHES/WARNINGS/ADVISORIES...
PUBLIC...NONE.
MARINE...NONE.
FIRE WEATHER...NONE.

&&

$$

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


000
FXAK69 PAFG 270745
AFDAFG

Northern Alaska Forecast Discussion
National Weather Service Fairbanks AK
1145 PM AKDT Sun Jun 26 2022

.SYNOPSIS...
Classic summer pattern for the Interior with ridging aloft keeping
it warm and mostly dry from the Central Interior eastward. Out
west, a Bering sea trough continues to pump in cooler and more
moist flow inland along the West Coast and Western Interior. South
flow brought record warmth to the North Slope today and will be
another warmer day (though not as warm) again. Wildfire smoke
continues to be an issue over the Interior.

&&

.DISCUSSION...

Upper Levels and Analysis...
Dominant features aloft are a 503 dam upper level trough near
Wrangel Island, a 547 dam low over the Bering Sea, and a 577 dam
ridge over the Copper Basin and Eastern Interior. Pressure
gradients are weak over the Interior with an anomalously strong
980 mb low north of Wrangel Island. A moderate strength south
gradient continues to blow over the West Coast and western Arctic.

Model Discussion...
Models are in excellent agreement with the general synoptic
pattern through the end of the week as ridging rebuilds slowly
after Wednesday. The notable difference is the ECMWF/Canadian are
much sharper with a shortwave trough moving across the eastern
Arctic on Tuesday and Tuesday night, which results in stronger
wind fields and more precip. That solution was favored.

Central and Eastern Interior...
Warm and smoky with a very similar day as yesterday as temps rise
to near 80, albeit moderated slightly by smoke. Isolated
thunderstorms will be possible over the Fortymile Uplands and
Eastern Ak Range. Tuesday a trough will move a "cool" front east
and will bring temps down 4-6 degrees, and will also increase the
thunderstorm threat over the Fortymile and Eastern Alaska Range
given the forcing aloft. Wednesday and Thursday will be mostly dry
again and temps remaining seasonably warm albeit slightly cooler
than today. The other concern, smoke, will continue but south
winds today may help slightly as some smoke is lifted north. Smoke
looks to be worse again late Tuesday and beyond.

West Coast and Western Interior...
Cooler and wet through Monday as the flow remains southerly, with
enhanced south winds continuing over the Bering Strait/Bering
Coast from the Seward Pen north. A front will bring a shot of
light rain Monday, then the pattern gradually dries out Tuesday
through the end of the week as a weak ridge builds in and temps
respond by warming gradually. Wednesday through Friday look quite
dry with minimal precipitation chances.

North Slope and Brooks Range...
Record warmth today was the main story, and it will continue
tomorrow as more 70s grace the eastern half of the Arctic with 50s
and 60s over the west. A cool front will move east today and
Tuesday with temps dropping to more normal values behind this
front. Isolated thunder threats will be possible over the eastern
Brooks/Arctic Coast Tuesday as the front shifts eastward. Another
front will keep a strong southwest gradient over the western
Arctic Tuesday through Wednesday. All areas will see some light
showers as the front passes through.

Coastal Hazard Potential Days 3 and 4...None.

Extended Forecast Days 4-7...
The global models are now locked in through next weekend as an
Interior ridge rebuilds and temps rise again well above average
for the Interior Thu-Sun. Another front will move into the West
Coast as south flow reestablishes itself Friday and Saturday,
bringing more rain. Interior thunderstorm threats increase next
weekend as the upper ridge begins to get impinged upon troughing
from the west and south. It looks warm and summery for the
foreseeable future for the Interior.

&&

.FIRE WEATHER...
Similar day today as yesterday with cooler onshore flow out west
and Interior ridging, with readings near 80 again today and min RH
values in the upper 20s to low 30s. Isolated thunder relegated to
the Fortymile Uplands today, and possibly becoming widely
scattered Tuesday as a cool front swings through. This will drop
Interior temps 4-6 degrees and push min RH values into the 30s.
Temps gradually warm again Wed-Fri as ridging aloft rebuilds over
the eastern Interior. Drier and slightly warmer out west after
Tuesday, as well, as a weak ridge aloft builds in.

&&

.HYDROLOGY...
No major concerns.

&&

.AFG WATCHES/WARNINGS/ADVISORIES...
Small Craft Advisory for PKZ220-PKZ225-PKZ230.
&&

$$

AHSENMACHER JUN 22


000
FXAK67 PAJK 271210
AFDAJK

Southeast Alaska Forecast Discussion
National Weather Service Juneau AK
410 AM AKDT Mon Jun 27 2022

.SHORT TERM...No change to synoptic pattern with high pressure
over the gulf persisting through the period. Marine layer is
pretty similar to 24 hours. It`s evident on sat imagery over the
gulf and N gulf coast, through Peril Strait, S Chatham, W Sumner
and Revillagigedo Channels. Main difference from 24 hours ago is
that it has not expanded much east of Lemesurier Island. Webcam
imagery and surface obs indicated dense fog over the S panhandle
so a dense fog advisory is in effect through mid morning.
Otherwise, another warm day across SE with max temps a few
degrees above yesterday`s readings. Winds will remain thermally
driven with sea breezes providing strongest winds over the inner
channels with W-NWly winds to 25kt today over the gulf. Forecast
confidence remains above average with synoptic pattern and the
main forecast challenge remains the progression of the marine
layer through the day.

.LONG TERM...Dry conditions will continue for most of Southeast
Alaska through the extended range forecast period. The notable
exception will be locations closest to the Coast Mountains, and
Misty Fjords in particular. Shower activity will return to that
region on Tuesday and persist through Wednesday afternoon. By
Wednesday evening, shower activity will shift north, to the Juneau
icefield, White Pass, and the border at the west end of the
Haines Highway. Conditions will likely dry out approaching next
weekend. Looking way out into the future, a front may approach
from the west sometime next weekend, but model agreement on that
does not exist at the present time.

With the abundant sunshine, expect sea breezes in the usual places
and at the usual times. Right now, the strongest surge looks like
it will be on Tuesday afternoon in Cross Sound and Icy Strait with
small craft westerlies lasting late into the evening. Have also
hinted at a similar situation for Wednesday afternoon & evening,
but do not have enough confidence to go with small craft winds
that far out into the future. On the outside, small craft
northwesterlies that begin in the short range forecast period will
persist through Tuesday night as a ridge builds over the Gulf and
then shifts east.

Daytime highs will remain well above normal on Tuesday and
Wednesday with temps rising to the mid 80s over the most inland
locations. Temps will moderate somewhat by Thursday to the upper
60s and mid 70s. While this may sound like a relief, those values
will still be above normal for this time of the year. So turn off
the pellet stove, grill outside, and keep the garden hose handy
for a quick cool down when it gets to be too uncomfortable. And
drink a lot of water to stay hydrated.

&&

.AVIATION...IFR conditions due to low clouds and fog continue to
plague portions of the outer coast and southern panhandle this
morning as low marine layer clouds creep inland. Low clouds and
fog are expected to again retreat into the gulf again today before
coming back tonight with more IFR or lower conditions mainly for
the outer coast and southern panhandle again. Highest winds will
still be associated with afternoon sea breezes for the next few
days.

&&

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...Dense Fog Advisory until 8 AM AKDT this morning for AKZ027-028.
MARINE...Small Craft Advisory for PKZ021-022-032-041>043-051-052.

&&

$$

EAL/BC/Fritsch

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