Graphical Hydro Meteorological Discussion

000
FXAK68 PAFC 280100
AFDAFC

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

.ANALYSIS AND UPPER LEVELS...

Very little has changed objectively from the past few days
regarding the current analysis. In Southcentral, eastern areas
remain cloud free to start the day but are developing convection
this afternoon. The marine stratus layer moved into the Cook Inlet
region for the third consecutive day this morning, but has long
since dissipated from most areas. Much more broken marine stratus
continues across all of the Gulf as compared with previous days,
as the high pressure area shifts over to the eastern Gulf.

Across Southwest Alaska, most of the area is under a broken
stratus deck, as lingering moisture associated with an essentially
dissipated front keeps the cloud cover in place. Further,
southerly flow continues to move Pacific moisture into the area in
the form of cloud cover. Unfortunately, no much needed rainfall is
expected except on the stray shower or two that forms this
afternoon due to solar heating.

A large low is over the western Bering. This is drawing a plume
of Pacific moisture northward into the central Bering. Very little
in the way of impacts are occurring as a result of this low. Broad
southerly flow from the coast of the mainland through the Central
Aleutians is keeping a steady southerly breeze going through the
the gaps.

In the upper levels, a large upper level high remains centered
along the Alaska/Yukon border with a large upper level low
centered over the western Bering. A 70 kt southerly jet streak is
along the Alaska Range into northern Alaska.

&&

.MODEL DISCUSSION...

The models are in good agreement through Wednesday afternoon. The
main points of uncertainty really fall to mesoscale differences in
the coverage and locations of thunderstorm development across
Southcentral through Wednesday. This is partially tied to how far
south a fast-moving front moves across northern Alaska. The models
have been coming into better agreement on this feature, however,
with most suggesting there will be very little if any influence by
this feature on the weather anywhere in southern Alaska. Forecast
confidence is high.

&&

.AVIATION...

PANC...VFR conditions and light winds will persist.

&&

.FIRE WEATHER...

Southcentral: Fire weather conditions will be gradually
deteriorating. An upper level high that for the most part remains
in place the next couple days will keep the Copper River Basin in
particular on the hot and dry side. That said, the heat will
increase the instability over that area. Thus, isolated
thunderstorms are expected this afternoon as a few storms are able
to break the cap. On Tuesday the high weakens and moves further
east into the Yukon. This will allow an easterly flow to collide
against the Alaska Range and Wrangell Mountains. Combined with
available moisture and instability, widely scattered wet storms
are expected, which may cause additional fire starts. Instability
thunderstorms are likely further west along the Alaska Range and
in the Talkeetnas on Tuesday. By Wednesday, convective coverage
will increase by leaps and bounds aerially. Widely scattered wet
thunderstorms are expected from the Kenai Mountains through most
of Anchorage, the Mat-Su, and over to the Copper River Basin.
While there will be very little in the way of forcing, full
sunshine combined with a continually weakening cap will allow for
widely scattered pop up thunderstorms. With zero in the way of
flow, the storms will largely rain themselves out and any forcing
for new storms will be the gust fronts of old storms.

Southwest: A dissipating front, widespread cloud cover, and much
cooler temperatures will keep all fire weather concerns minimal
this afternoon and Tuesday. On Wednesday, upper level ridging
moves over Southwest Alaska, which should allow enough instability
to develop for a few isolated thunderstorms to form in the Alaska
Range and in parts of the Kuskokwim Mountains.

&&

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

A longwave ridge persists over Eastern Alaska. The marine layer
that has been creeping up Cook Inlet for the past several days is
expected to remain at bay through the short-term. With clearing
skies ahead, expect temperatures to climb into the 70s and 80s.
These higher temperatures will lead to an increase in thunderstorm
activity for the next several days. Today`s thunderstorms should
remain mostly limited to the northeastern Copper River Basin.
However, the areal coverage of thunderstorms is expected to
increase through Tuesday and Wednesday afternoon.

For Tuesday, thunderstorms are expected across the northern
Copper River Basin and Talkeetna Mountains. On Wednesday and
Thursday, thunderstorms will spread across much of the Copper
River Basin and extend from the Talkeetna Mountains, through the
Chugach Front Range, and to the Kenai Mountains. There remains
some question about how intense these thunderstorms, and their
lightning activity, may get. While there will be a considerable
amount of instability associated with the thermal low, weak winds
under the ridge and little in the way of forcing suggest that
these storms will not become well-organized or particularly long-
lived. Weak steering flow will likely keep these storms, and their
rain, restricted to the mountains.

&&

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

The front that brought rain and widespread cloud cover to much of
Southwest will continue to dissipate heading into the overnight
hours. Any residual rain showers are expected to dissipate near to
just after midnight. Upper level heights will continue to build
over much of Southwest as a weak upper level ridge moves overhead.
As a result, the next few days will feature drier, warmer, and
sunnier conditions especially for interior Bristol Bay and the
Middle Kuskokwim Valley. However, there will be some embedded weak
upper level shortwaves traversing around this weak ridge. Due to
this, there is the risk for afternoon and evening convection.
Tuesday continues to look very marginal as weak shortwaves move
over the region and instability remains weak. Think anything that
develops will mostly be rain showers. Also, 850 mb temperatures
are warming indicating a capping inversion aloft.

Wednesday and Thursday, instability continues to increase as the
weak ridge remains overhead. However, the upper level shortwaves
will be a bit stronger on Wednesday before becoming even stronger
on Thursday providing more lift in the atmosphere each day. In
conjunction with the shortwaves becoming stronger, 850 mb
temperatures continue to warm indicating a strengthening capping
inversion. Therefore, the convection forecast remains rather
difficult for these 3 days as anything that tries to develop will
have to punch through the cap. It may very well just end up being
towering cumulus clouds that develop that never mature into a
thunderstorm. Also, the most likely places for convection if it
did come to fruition would be across the Western Alaska Range
mainly from Lime Village east and the Ahklun Mountains/Kilbuck
Mountains. Temperatures also become warmer each day with Wednesday
and Thursday being the warmest days with widespread 70s and
perhaps even an 80 degree reading in the Middle Kuskokwim Valley.
Closer to the coast temperatures will remain in the 50s to 60s.

&&

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

Upper level troughing remains across the Bering for the next
couple days keeping the area unsettled. A low pressure system
currently located northwest of Adak moves northward and then
northwestward into the southwest Bering Sea Tuesday and virtually
stalls. Its associated front continues moving eastward along the
Aleutian Chain reaching Dutch Harbor and the Pribilofs Tuesday
afternoon. The front is expected to stall here overnight as
it bangs against the strong ridge to the east halting its eastward
progress. As a result, it will undergo frontolysis (decaying
front) Tuesday night. Another system moves towards the Central
Aleutians Wednesday morning bringing another round of unsettled
weather. This system continues northward into the Bering Wednesday
night spreading periods of rain and gusty winds eastward towards
the Eastern Aleutians and southern Alaska Peninsula for Wednesday
night through Thursday. The Pribilofs will also get in on the
action Wednesday evening through Thursday as the low pressure
system moves northward through the Bering and sends its front
eastward through the area. This system also looks to be much
wetter than the previous one as it brings a deeper fetch of
moisture northward from the North Pacific.

&&

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

Bering Sea/Aleutians: A low in the central Bering Sea will
push a front from the central Aleutians to the Alaska Peninsula
through Friday. There is a low probability that gale force winds
will develop over the northern Bering on Thursday along this
front, before the low tracks into the Russian Far East. Localized
southerly gale force gap winds, however, will be possible from
the eastern Aleutians through the southern Alaska Peninsula into
late Thursday. For Friday, there is a slight chance for another
round of southerly gale force gap winds through the eastern
Aleutians and Alaska Peninsula as a weak North Pacific low tracks
into the Bering. By Saturday, winds across the region remain
below gale force. 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: Friday through
Monday)...

A pattern change is in store for this upcoming weekend. The ridge
of high pressure sitting nearly stationary over the Alaska-Canada
border this week will begin to be nudged eastward on Friday as a
low pressure system develops at the base of the longwave trough
set up across the Bering Sea/Aleutian Islands. As the trough
swings eastward, a weak triple-point surface low and attendant
front tracks from Southwest Alaska and the Alaska Peninsula on
Friday to the Western Alaska Range and Kenai Peninsula by Sunday
morning. Under this regime, Southwest Alaska will remain cool and
wet. For Southcentral Alaska, initially above normal temperatures
will decrease somewhat as the trough approaches, bringing a
cooler airmass and increased moisture to the region. While
rainfall will initially accompany the front as it reaches the
Kenai Peninsula, it looks to stall and dry out on Sunday. There is
some indication the weak surface low persists in the Gulf of
Alaska through Monday, providing the instability to support
rain showers along the Gulf coast and potentially over high
terrain. However, inland areas of Southcentral are expected to
remain mostly dry. Over the Bering Sea/Aleutians, a series of
shortwave troughs keep the region active with periods of rain
showers through the weekend.

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

&&

$$

SYNOPSIS AND MODEL DISCUSSION...JW
SOUTHCENTRAL ALASKA...KC
SOUTHWEST ALASKA/BERING SEA/ALEUTIANS...MV
MARINE/LONG TERM...CQ

000
FXAK69 PAFG 280802
AFDAFG

Northern Alaska Forecast Discussion
National Weather Service Fairbanks AK
1202 AM AKDT Tue Jun 28 2022

.SYNOPSIS...
A smoke filled Interior summer rolls on. Today will be slightly
cooler, but heat returns Wednesday through the weekend, along with
continued bouts of dense smoke. Out west, rain and cloudy weather
finally ends and a gradual warming commences through Thursday
before the next front moves in. An unusually strong low up north
will keep strong winds over the North Slope.

&&

.DISCUSSION...

Upper Levels and Analysis...
There is a 504 dam upper closed arctic low not too far away from
the North Pole. There is a basal shortwave trough over the Chukchi
Sea moving east into the western Arctic. There is a 574 dam upper
ridge over the Copper Basin and Eastern Interior. Over the Bering,
there is a cutoff upper low around 549 dam. There is a "cool
front" moving east into the Eastern Interior this morning, with a
much stronger gradient over the Chukchi as southwest winds
continue to barrage the arctic.

Model Discussion...
Models are now locked in through the next 60 hours then diverge
subtly with a front moving into Southwest AK from the Bering Sea.
The ECMWF is fastest while the American guidance is faster by
12-15 hours. A middle ground will be favored to maintain
consistency which brings rain to SW AK on Friday. Over the
Interior, it is going to start baking as the ridge rebuilds, and
all models are in good agreement with this.

Central and Eastern Interior...
Slightly cooler today but with continued widespread areas of smoke
and poor air quality as west winds push wildfire smoke into all of
the Interior and down to the Alaska Range. Widely scattered
thunderstorms will occur today over the Fortymile Uplands and
Eastern AK Range near the ALCAN as the front shifts east.
Otherwise, most of the Interior is dry again.

Wednesday through Friday is just gets warmer each day again as the
ridge rebuilds, with daily PM thunderstorm chances over the Alaska
Range. Expect temps into the mid 80s by late week for low
elevation areas.

West Coast and Western Interior...
Gradual drying and warming as ridging slow builds through
Thursday. The Interior will warm the fastest with temps back into
the 70s and even low 80s by Thursday. Some stratus and fog will
persist over the coast but it too should warm up by Thursday as
the low level winds become offshore.

North Slope and Brooks Range...
Showery and "cooler" as a front crosses eastward over the North
Slope through today. Heavy showers and isolated thunderstorms will
occur over the eastern Arctic and Brooks Range, later this
afternoon and early evening. Strong southwest winds and some
showers will impact the western Arctic Wednesday as a strong
front moves into the higher arctic. Weather quiets down Thursday
as high pressure aloft takes hold.

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

Extended Forecast Days 4-7...
Friday through the weekend will be hot over the Interior as
another ridge takes hold and a front moves into the West Coast.
Thunderstorm threats also increase as a strong thermal trough
forms north of the AK Range sometime Saturday. Expect widespread
smoke over the Interior with warmth over the North Slope, as well.

&&

.FIRE WEATHER...
"Cooler" today by 3-5 degrees over the Interior while warming
gradually out west as a ridge slowly builds in through Thursday.
West winds today will become gusty especially north of the Tanana
River Valley. Widely scattered thunderstorms will be possible
over the Fortymile Uplands and Eastern AK Range today as the cool
front moves east. Wednesday and beyond, the entire Mainland warms
back up under ridging, but the eastern Interior/Central Interior
will get toasty as temps shoot into the mid 80s late week, with
min RH values back into the 20s. Dense smoke will continue from
the AK Range north.

&&

.HYDROLOGY...
No major concerns.

&&

.AFG WATCHES/WARNINGS/ADVISORIES...
Dense Smoke Advisory for AKZ221.

Small Craft Advisory for PKZ220.

Gale Warning for PKZ225-PKZ230-PKZ500

&&

$$

AHSENMACHER JUN 22

000
FXAK67 PAJK 272349
AFDAJK

Southeast Alaska Forecast Discussion
National Weather Service Juneau AK
349 PM AKDT Mon Jun 27 2022

.SHORT TERM...Persistence continues to be the best forecast
strategy with respect to the marine layer over the Gulf and early
morning fog. The thermal difference between the cool air under the
gulf marine layer (53F) and the inner land areas (70-80F) will
enhance the afternoon/early evening westerly sea breeze through
Cross Sound and Icy Strait up to 25kt. This should help to push
marine clouds back down the channel tonight.

An inverted trough over the southern inner channels will shift
northward on Tuesday, causing winds to shift S and increase to
15kt in Clarence Strait. That wind shift should limit daytime
heating and may keep more clouds around after the AM fog.

High temperatures were lowered some for Tuesday based on sea breeze
winds kicking in again and marine layer clouds limiting temps along
the outer coast. One place that has been affected quite a bit by
the sea breeze is Skagway. Typically for them to reach record
highs, the wind direction needs to stay offshore (northerly). It
now looks like Skagway will sea breeze again on Tuesday, although
light as they did today, but Haines might stay W-NW and reach the
mid 80s for the upper Chilkat Valley.

The warm temperatures extend up through the atmosphere with
freezing levels above 10kft. This is causing rivers around Haines
and Skagway to steadily rise and may be near bankful on Tuesday
with high water in locally known trouble spots.

.LONG TERM...Generally speaking, the pattern persists through the
latter half of the week with a ridge in the gulf. Dry conditions
are expected to continue for most of SE AK heading into the next
weekend. The only exceptions to this are stray showers near the
Coast Mountains and maybe some mist associated with the advancing
/ retreating cycles of the marine layer near the coast. 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. Model 850mb temperatures show a slight cool down
Wednesday and Thursday before rebounding back into the 12-15C
range for Saturday. The cool down Wednesday and Thursday coincides
with a weak southerly marine push. Surface winds turn back to the
north again with offshore flow Friday into the weekend, so more
above average temperatures are likely. Raised temperatures a bit
for Friday and Saturday, with more rises possible if model trends
continue. Keep the sunglasses and sunscreen handy.

&&

.AJK WATCHES/WARNINGS/ADVISORIES...
PUBLIC...Dense Fog Advisory from 2 AM to 9 AM AKDT Tuesday for AKZ020-022-
027-028.
MARINE...Small Craft Advisory for PKZ021-022-032-041>043-052.

&&

$$

Ferrin/BFL

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